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Non-thermal atmospheric pressure plasma has been proposed as a new tool for various biological and medical applications. Plasma in close proximity to cell culture media or water creates reactive oxygen and nitrogen species containing solutions known as plasma-activated media (PAM) or plasma-activated water (PAW) - the latter even displays acidification. These plasma-treated solutions remain stable for several days with respect to the storage temperature. Recently, PAM and PAW have been widely studied for many biomedical applications. Here, we reviewed promising reports demonstrating plasma-liquid interaction chemistry and the application of PAM or PAW as an anti-cancer, anti-metastatic, antimicrobial, regenerative medicine for blood coagulation and even as a dental treatment agent. We also discuss the role of PAM on cancer initiation cells (spheroids or cancer stem cells), on the epithelial mesenchymal transition, and when used for metastasis inhibition considering its anticancer effects. The roles of PAW in controlling plant disease, seed decontamination, seed germination and plant growth are also considered in this review manuscript. Finally, we emphasize the future prospects of PAM, PAW or plasma-activated solutions in biomedical applications with a discussion of the mechanisms and the stability and safety issues in relation to humans.
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Biol. Chem. 2018; aop
Review
Nagendra Kumar Kaushika,*, Bhagirath Ghimirea, Ying Lia, Manish Adhikaria, Mayura Veeranaa,
Neha Kaushika, Nayansi Jhaa, Bhawana Adhikari, Su-Jae Lee, Kai Masur, Thomas von Woedtke,
Klaus-Dieter Weltmann and Eun Ha Choi*
Biological and medical applications of plasma-
activated media, water and solutions
https://doi.org/10.1515/hsz-2018-0226
Received April 18, 2018; accepted July 11, 2018
Abstract: Non-thermal atmospheric pressure plasma has
been proposed as a new tool for various biological and
medical applications. Plasma in close proximity to cell
culture media or water creates reactive oxygen and nitro-
gen species containing solutions known as plasma-acti-
vated media (PAM) or plasma-activated water (PAW) – the
latter even displays acidification. These plasma-treated
solutions remain stable for several days with respect to
the storage temperature. Recently, PAM and PAW have
been widely studied for many biomedical applications.
Here, we reviewed promising reports demonstrating
plasma-liquid interaction chemistry and the application
of PAM or PAW as an anti-cancer, anti-metastatic, anti-
microbial, regenerative medicine for blood coagulation
and even as a dental treatment agent. We also discuss
the role of PAM on cancer initiation cells (spheroids or
cancer stem cells), on the epithelial mesenchymal tran-
sition (EMT), and when used for metastasis inhibition
considering its anticancer effects. The roles of PAW in
controlling plant disease, seed decontamination, seed
germination and plant growth are also considered in
this review. Finally, we emphasize the future prospects
of PAM, PAW or plasma-activated solutions in biomedi-
cal applications with a discussion of the mechanisms and
the stability and safety issues in relation to humans.
Keywords: anticancer; antimicrobial; cold atmospheric
pressure plasma; dental application; plasma-activated
media; plasma-activated water.
Introduction
Over the past few years, atmospheric pressure plasma
sources (herein referred to as ‘plasmas’) have gained
enormous amounts of attention due to their wide range of
applications in the diverse fields of biology and medicine,
including wound healing, the sterilization of surfaces,
blood coagulation, root canal treatments, cancer treat-
ments and skin treatments, among others (Fridman etal.,
2008; Kolb etal., 2008; Shashurin etal., 2008; Dobrynin
et al., 2009; Oehmigen etal., 2010; Heinlin et al., 2011;
Helmke etal. 2011; Graves, 2012; Lukes etal., 2012; Park
etal., 2012; Ikehara et al., 2013; Keidar etal., 2013; Pan
etal., 2013; Haertel etal., 2014; Tanaka etal., 2014; Yousfi
et al., 2014; Fthollah et al., 2016; Kaushik et al., 2016;
Lin etal., 2017; Kuninova etal., 2017; Weltmann and von
Woedtke, 2017). Though some plasma devices are being
commercialized, few of them are available in clinics.
These developments have given rise to a new field of medi-
cine called ‘plasma medicine’, which is set to revolution-
ize the treatment of skin diseases such as melanoma or
even dental infections.
The principle of plasma medicine is based on the
direct or indirect application of an electrical discharge to
a biological target. The electrical discharge or plasma is
generally obtained by applying high voltage to an active
electrode with the help of working gases such as helium,
aNagendra Kumar Kaushik, Bhagirath Ghimire, Ying Li, Manish
Adhikari, Mayura Veerana, Neha Kaushik and Nayansi Jha: These
authors contributed equally to this work.
*Corresponding authors: Nagendra Kumar Kaushik and
EunHaChoi, Plasma Bioscience Research Center, Applied Plasma
Medicine Center, Department of Electrical and Biological Physics
and Department of Plasma-Bio Display, Kwangwoon University,
Seoul 01897, Republic of Korea, e-mail: kaushik.nagendra@kw.ac.kr
(N.K. Kaushik); ehchoi@kw.ac.kr (E.H. Choi)
Bhagirath Ghimire, Ying Li, Manish Adhikari, Mayura Veerana and
Bhawana Adhikari: Plasma Bioscience Research Center, Applied
Plasma Medicine Center, Department of Electrical and Biological
Physics and Department of Plasma-Bio Display, Kwangwoon
University, Seoul 01897, Republic of Korea
Neha Kaushik and Su-Jae Lee: Department of Life Science, Hanyang
University, Seoul 04763, Republic of Korea
Nayansi Jha: Graduate School of Clinical Dentistry, Korea University,
Seoul 02841, Republic of Korea
Kai Masur, Thomas von Woedtke and Klaus-Dieter Weltmann:
Leibniz Institute for Plasma Science and Technology, D-17489
Greifswald, Germany
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2 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
argon, neon, nitrogen, oxygen, air or their admixtures
(Kuok, 2017). Most of the applied energy is dissipated
in the ionization of neutral gas molecules and atoms,
resulting in the formation of electrons, excited or ionized
atoms, ultra-violet rays (UV), electric fields (EF), mild heat
and other effects, with temperatures close to that of the
ambient environment. Excited/ionized atoms combine
with other atoms of the working (or surrounding) gas,
resulting in the formation of abundant reactive oxygen
and nitrogen species (RONS) which can be used in a broad
range of biomedical applications. Based on this principle,
many plasma devices, such as plasma jets and dielectric
barrier discharge (DBD) sources with various configura-
tions, have been developed throughout the world (Lu
et al., 2012a,b; Winter et al., 2015; Brandenburg, 2017;
Laroussi etal., 2017). Moreover, a guide for a testing pro-
cedure for cold plasma devices has been developed for
comparisons of safe applications of these plasma devices
in clinics (Mann etal., 2016).
When an atmospheric pressure plasma source is
operated in an ambient environment, it produces reactive
oxygen species (ROS) and reactive nitrogen species (RNS),
which are collectively known as RONS. These RONS are the
key species which have made plasma sources feasible for
use with various biomedical applications. When plasma
sources are applied for biomedical use, a specific target
may require an on-site or off-site treatment. With on-site
treatments, the active discharge zone or plasma plume at
ambient temperatures comes into direct contact with the
biological target. This may be beneficial for the treatment
of severely affected wounds and for conditions in which
the plasma source is readily available (Akimoto et al.,
2016; Bekeschus etal., 2016). During an off-site treatment,
a biological solution is exposed directly or indirectly to the
plasma source for a predetermined time. Upon the plasma
treatment, the plasma-treated solution is enriched with
a variety of long-lived RONS with lifetimes ranging from
hours to several days, with further utilization possible for
particular biomedical applications. It can also be carried
to places where plasma generation is not possible, such as
in small organs and cavities which are difficult to reach.
This type of solution can act as a drug, also known as
plasma-activated media (PAM) or plasma-activated water
(PAW).
Presently, PAM generation is emerging as a promising
new tool in the world of plasma medicine. PAM has shown
some very promising results in relation to living tissue
sterilization, blood coagulation, the destruction of cancer
cells, and many other medical applications, such as
wound healing, as a medical disinfectant for equipment,
and even as a type of mouthwash for dental problems. It
is unique because it is stable at room temperature and
does not harm healthy tissue at effective doses; rather,
it generates reactive species inside tissues in the body.
The efficacy of PAM depends on many factors, such as
the plasma exposure dose, the storage duration, and the
storage temperature. Cold plasma has also emerged as a
major treatment option in the dental field (e.g. mouth-
wash agents, sterilization agents for dental equipment)
(Jha etal., 2017). Here, we discuss the preparation of PAM,
its RONS chemistry, and various biological and therapeu-
tic effects. A discussion of PAW for sterilization, dental,
agriculture and other important biological applications is
also included in this review report.
Reactive species formed in PAM
andrelated chemistry
PAM refers to the indirect application of an electrical dis-
charge to biological targets (Brisset and Pawlat, 2016; Judée
etal., 2016; Verlackt etal., 2018). The solution obtained
after the direct exposure to plasma is transferred to the
biological target. A schematic diagram of the preparation
of a plasma-activated drug using a conventional plasma
jet is shown in Figure 1. The parameters that can vary and
change the characteristics of the drug are enclosed by the
red dotted rectangles. The main component of the working
gas is normally inert, such as argon, helium or neon. This
is necessary to produce the discharge at a lower input
energy level. Additional gases such as nitrogen, oxygen,
water vapor and their mixtures can be included in the
main gas to change the production of the reactive species.
The dielectric material can be quartz, glass, acryl, or even
Teflon, and the high-voltage electrode consists of a con-
ductive material such as copper, stainless steel, or silver.
This type of plasma jet can be operated with or without a
ground electrode. Plasma jets have been developed with
and without ground electrodes (Lu etal., 2012a,b; Winter
etal., 2015; Brandenburg, 2017; Laroussi etal., 2017), but
their operation has been reported to be safer and more
stable with the use of a ground electrode (Lu etal., 2008;
Kim etal., 2015). The production of reactive species in a
plasma jet is realized by applying high-voltage alternating
current through a high-voltage electrode, and a plasma
jet plume ranging from a few millimeters to several centi-
meters can be observed by the naked eye (Thiyagarajan
etal., 2013; Kostov etal., 2015).
The delivery of active constituents inside PAM can
occur through the generation of plasma in two ways: (a)
outside the liquid environment and (b) inside the liquid
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids3
environment. Schematic diagrams of the two methods
are shown in Figure 1A and B, respectively. When a plasma
source (typically a plasma jet, see Figure 1A) is operated
outside the liquid environment, the active constituents
can form through the direct interaction (touch) and indi-
rect interaction (non-touch) modes of the plasma plume
(Norberg etal., 2014). In the non-touch condition, the
biological solution is placed directly below the plasma
source, where there is no direct contact between the
visible part of the plasma plume and the liquid surface.
RONS initially generated by plasma-air interaction
in the gas phase subsequently dissolve/accumulate
into the solution. In the touch condition, plasma is in
direct contact with the biological solution. In addition
to the accumulation of reactive species from plasma-
air interactions, numerous additional reactive species
generated through the plasma-liquid interactions are
delivered into the solution. The formation of reactive
species is significantly enhanced in this condition, as
the excited/ionized atoms combine with both ambient
gas molecules as well as water molecules. On the other
hand, plasma inside the liquid environment is usually
generated through bubbles caused by the gas flow
(Levko etal., 2016; Zhang etal., 2016; Chen etal., 2017).
A longer generation time of the plasma within the liquid
environment has been found to produce more reactive
nitrogen species and fewer ROS (Chen etal., 2016). The
solution prepared using either of these methods acts
as a bioactive solution for a range of components and
it can be transported to a target for specific biomedical
applications.
The formation of the active constituents in PAM can be
altered by changing certain plasma-processing parameters,
such as the working gas, gas flow rate, treatment time,
plasma-liquid gap distance, target liquid solution type and
its quantity, for instance, in accordance with a change in
the supplied energy. This can be more or less important
depending on the different buffers and antioxidants within
the solution (Norberg et al., 2014; Dai et al., 2015; Baek
et al., 2016; Io et al., 2016; Kawasaki etal., 2016; Uchida
etal., 2016, 2017; Yue et al., 2016a,b; Chauvin etal., 2017;
Ghimire etal., 2017; Oh et al., 2018). A schematic diagram
of the formation of the active plasma constituents, i.e. of the
reactive species formed within the discharge region, the gas
phase (the interphase between the liquid discharges) and
inside the liquid with a conventional plasma jet is shown
in Figure 2. Neutral gas molecules (M) can be excited (to
M*) or ionized (to M+) by collisions with energetic electrons
(e) produced during the discharge in addition to the effect
of the EF and ultra-violet radiation (UV). Primary reactive
species such as hydroxyl radicals (OH), nitric oxide radicals
(NO), super-oxide radicals (O2
*−), atomic oxygen (O), singlet
oxygen (1O2) and excited nitrogen (N) are directly produced
in the discharge region due to the interaction between elec-
trons and the feeding gas (or ambient gas) molecules. These
species are relatively short-lived, and their concentration
within the discharge region is very high. Various diag-
nostics techniques such as optical emission spectroscopy
Working gas
AB
Working gas
Dielectric
(quartz tube)
Dielectric material
High voltage
electrode
Plasma plume
Gap distance
dLiquid solution
Liquid solution
Plasma
High voltage electrode
Figure 1:Schematic diagram showing the preparation method of PAM through plasma (A) outside a liquid environment, and (B) inside a
liquid environment.
The parts enclosed inside the dotted rectangles are the parameters that can be varied to change the characteristics of PAM in addition to the
treatment time and supplied energy.
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4 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
(OES), laser-induced fluorescence (LIF), UV absorption
spectroscopy (UV-VIS), electron spin resonance (ESR),
cavity-enhanced absorption spectroscopy (CEAS), and
calorimetric methods have been utilized to obtain quali-
tative information pertaining to these species outside and
inside the liquid surface (Srivastava and Wang, 2011; Tresp
etal., 2013; Girard etal., 2016; Yue etal. 2016a,b; Ghimire
etal., 2017). The concentration of OH radicals in an ambient
environment is as high as 1×1015cm−3, as reported in other
studies (Nikirov et al., 2011; Kim etal., 2014; Attri etal.,
2015; Xiong et al., 2015). Moreover, the reported atomic
oxygen concentration is 1×1015 cm−3 (Knake et al., 2008;
Reuter etal., 2009; Dvorak etal., 2017). These species are
converted to secondary/long-lived species such as hydro-
gen peroxide (H2O2), nitrate (NO2), nitrite (NO3), and ozone
(O3) in an ambient environment. Primary reactive species
may again interact with ambient air molecules, leading to
the re-formation of these species. The species generated
in the gas phase can go to the liquid phase and dissolve in
a liquid solution. H2O2 is highly soluble in water. NO2 and
NO3 are converted to NO2
and NO3
, respectively. However,
the chemistry of RONS formation differs depending on
whether the plasma plume is touching or not touching the
water surface. The creation and destruction processes of
various RONS produced in non-thermal plasma sources are
described in Table 1.
Though numerous short-lived species, as shown
above, form during the discharge, they are readily con-
verted into stable species within a short time. Owing to
the long lifetimes of the major constituents, in this case,
H2O2, NO, NO2, NO3 and HNO3, among others, PAM can
be stored for several days and can also be transported to
remote regions where plasma sources are unavailable.
Although PAM is made up of similar constituents, it can
be applied to a wide range of applications. For example,
H2O2 – depending upon its concentration – can act as an
effective apoptosis/necrosis inducer and can be applied
to treat cancer cells (Troyano et al., 2003; Xiang et al.,
2016). The same compound exhibits bleaching proper-
ties, suggesting its potential for use as a teeth whitening
agent (Tredwin etal., 2006). It has also been applied in
the sterilization and agriculture areas due to its effective-
ness when used to kill bacteria and fungi (Linley etal.,
2012; Friedline et al., 2015). On the other hand, NO is a
multi-faceted molecule with dichotomous regulatory
roles in many areas of biology. As a signaling molecule, it
activates various processes in a biological system. It also
affects cellular decisions about cell life and death either
by turning on apoptotic pathways or by shutting them off
(Kim et al., 2001; Brune etal., 2003). The derived com-
ponents of NO, such as nitrates and nitrites, assist in the
growth of plants, thus widening the applicability of PAM
in agriculture (Mancinelli and Mckay, 1983). Brief descrip-
tions of the major plasma constituents in specific applica-
tions are provided in the following sections.
RONS are regarded as key factors
in PAM-induced apoptosis
It is believed that RONS themselves or the RONS-derived
species contained in PAM may be the key factors leading to
an anticancer effect (Lu etal., 2016). The short-lived RONS
produced by plasma discharge is converted into a relatively
Figure 2:Schematic diagram of the formation of active constituents in a plasma-activated medium with a conventional plasma jet.
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids5
Table 1:Creation and destruction pathways for the active constituents in PAM.
S. no. Reactive species Creation pathways Destruction pathways
. Hydroxyl radical (OH)
(Pei etal., ; Attri
etal., ; Uhm, ;
Gorbanev etal., ; Yue
etal., a; Ghimire etal.,
)
e+HOOH+H+e
e+HOH+OH
M*+HOOH+H+M
e+OO(P)+O(D)
O(D)+HOOH
e+NN(AΣu
+)+e
N(AΣu
+)+HOOH+N+H
NO+HOOH+NO
O+HOH+O
UV+HOHO*
UV+HO*H++OH
OHOH+e
OH+OHHO
OH+HOHO+HO
N+OHNO+H
OH+OHO+O
. Nitric oxide
radical (NO)
(Uhm, ; Kurake etal.,
)
N+ONO
N+OHNO+H
N+ONO+O
N(AΣu
+)+NONO+O+N
N+O+MNO+M
N+ONO+O
N+ONO+O
N+O
*NO+O
N+O(S)NO+O
N*+ONO+O
N
*+ONO+N
N
*+ONO+NO+O
NO+NN+O
NO+ONO
NO+OHHNO
NO+HOHNO
NO+ONO
NO+HOONOOH
. Atomic oxygen (O)
(Yueetal., b)
e+OO+e
O+M*O+M
O+HOH+O
O+N(A,B,C)O+N(X)
O+O+MO+M
O+O+MO+M
. Singlet oxygen (O)
(Braginsky etal., )
e+OO
O+OO
O+OO+e
O+OO(P)+O
. Excited nitrogen (N)
(Braginsky etal., ;
Uhm, ; Kurake etal.,
)
e+NN
*+e
e+NN+N
O
*−+NO+N+N
N+ONO
N+OHNO+H
N+ONO+O
N(AΣu
+)+NONO+O+N
N+O+MNO+M
N+ONO+O
N+ONO+O
N+O
*NO+O
N+O(S)NO+O
N*+ONO+O
N
*+ONO+N
N
*+ONO+NO+O
. Superoxide (O
*)
(Braginsky etal., ;
Brisset and Pawlat, )
e+OO
*−
OH+HOO
*−+HO
ONOONO+O
*−
O
*−+NO+N+N
O
*−+NNO
. Hydrogen peroxide (HO)
(Attri etal., ; Uhm,
)
OH+OHHOOH+HOHO+HO
. Nitrate (NO)
(Lukes etal., ; Uhm,
; Joslin etal., ;
Kurake etal., )
NO+ONO
NO+ONO
HNO+OHHO+NO
HNONO
+H+
NO+NO+HONO
+NO
+H+
NO+OHONOOH
HO+NOHNO+O
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6 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
long-lived species, including H2O2, NOx and other uncharac-
terized species, which are responsible for the high and sus-
tained reactivity of PAM. RONS uptake, observed in many
cancer cell lines, results in cell injury, while the antitumor
effects of PAM are completely inhibited with NAC. NAC,
widely used as an antioxidant, directly scavenges OH, H2O2
and hypochlorous acid (HClO) but not O2
(Aruoma, 1998).
Therefore, at least one of these three reactive species is
responsible for PAM-induced cell injuries.
Ninomiya et al. demonstrated that the roles of OH-
radical-induced apoptosis are to increase both extracel-
lular (culture medium) and intracellular effects after a
plasma treatment in breast cancer cell lines (Ninomiya
etal., 2013). However, OH radicals, regarded as short-lived
species, will be converted into long-term stable species
such as hydrogen peroxide. H2O2 is considered to be
responsible for most of the activity in PAM-induced cell
injuries (Boehm etal., 2017). It can diffuse freely through
the cell membrane without disturbing it. However, prod-
ucts that cooperate with H2O2, such as organic peroxides,
can disturb the membrane structure and increase the per-
meability of the cell membrane, which can then become
the initial step for H2O2-induced cell injury, followed by
the influx of extracellular reactive species from PAM. H2O2-
scavenging reagents such as catalase or pyruvate mark-
edly attenuate the PAM anticancer effect. However, other
species have a cooperative role with H2O2, as evidenced
by the addition of H2O2 in a medium, which was found to
have a weaker killing effect than PAM when exposed to
lung adenocarcinoma cells (Adachi etal., 2015).
NO can easily penetrate the cell membrane and orga-
nelle membrane, causing an increase in intracellular ROS
and damage to mitochondria, thus ultimately triggering
apoptosis in cells. NO can quickly dissolve into water.
Specific types of PAM, such as NO-PAM, have also been
developed by purging NO gas into water. This process
eventually reaches an NO concentration of 140 μ. Exten-
sive NO radicals accumulate inside cervical cancer cells
and induce apoptosis (Li et al., 2017a). In an aqueous
solution, the half-life of NO can be sustained up to 24h
(Yan etal., 2014). However, other work has claimed that
NO has a short life and that it will quickly convert to NO2
and NO3
in PAM (Adachi etal., 2015). Moreover, NO2
up to
thousands of micromoles exhibits very little toxicity with
regard to the glioblastoma cell line; however, when adding
NO2
to H2O2, it has a synergistic effect that enhances
S. no. Reactive species Creation pathways Destruction pathways
. Nitrite (NO)
(Braginsky etal., ;
Lukesetal., )
NO+ONO
NO+ONO+O
HNONO
+H+
NO
+ONO
+O
NO+NO+HONO
+NO
+H+
NO+NO+HONO
+H+
ONOOHNO
+H+
NO+NONO+NO
NO+NONO+NO+O
. Peroxynitrate (ONOO)
(Braginsky etal., ;
Brissetand Pawlat, )
O
*−+NOONOO
OH+NOONOO+H+
ONOONO+O
*−
. Nitrous acid (HNO)
(Uhm,)
NO+OHHNO
HO+NOHNO+O
HNO+OHHO+NO
HNONO+NO+HO
. Nitric acid (HNO)
(Uhm, )
NO+OHHNO
NO+HOHNO
. Ozone (O)
(Braginsky etal., ;
Uhm,)
O+OOOH+OHO+O
. Peroxynitrous acid (ONOOH)
(Lukes etal., )
NO+HOONOOH
NO+OHONOOH
ONOOHOH+NO
. Hydrogen dioxide (HO)
(Uhm, )
HO+OHHO+HO
HNO+OHHO+NO
OH+OHO+O
H+OHO
NO+HOHNO
HO+NOHNO+O
Table 1(continued)
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids7
the H2O2 killing ability, though this is still not as strong
as a PAM treatment (as shown in Figure 3; Kurake etal.,
2016). The stronger anticancer activity of PAM than H2O2
and NO2
added to a medium indicates that other reac-
tive species also play a non-negligible role (Kurake etal.,
2016). On the other hand, NO2
or NO radicals and H2O2
react to generate peroxynitrite (ONOO), which is toxic
and which will attack important macromolecules in cells,
possibly leading to the NO2
synergistic effect with H2O2.
The ability to cause PAM-triggered cell injuries depends
on several factors, such as the medium type, the seeding
cell density and the PAM volume. If the medium contains a
RONS quenching reagent, for example, pyruvate in DMEM
6429, it will reduce the PAM anticancer effect. A lower
seeding density and a greater volume of PAM induce a higher
cell injury percentage due to catalase activity of the seeded
cell number and the RONS amount in the PAM volume
(Adachi etal., 2015). Another important factor in relation
to PAM is fetal bovine serum (FBS). The anticancer capac-
ity of PAM can feasibly be controlled by regulating the FBS
concentration in the medium and the storage temperature
of PAM. Yan and colleagues demonstrated that FBS plays a
protective role for U87 cells in PAM. The killing capacity of
PAM decreases as the concentration of FBS is increased. A
similar phenomenon was also found by another research
group, who showed that the presence of FBS in PAM was
to act as a RONS scavenger with a lower cancer cell killing
effect (Yan etal., 2014). Due to the FBS scavenging effect,
the H2O2 concentration in PAM increases linearly with the
plasma treatment time at a slower rate for media with
FBS as compared to media without FBS. However, the
linear NO2
concentration increase with the plasma treat-
ment time was not affected by the presence of FBS in the
medium (Kurake etal., 2016). This suggests that FBS can
scavenge more with ROS rather than with RNS. This may
also contribute to the storage instability of PAM. Moreover,
an in vivo experiment showed that tumor volumes were not
completely inhibited by PAM, likely because various RONS
scavengers in living tissue neutralizes the RONS contained
in PAM. The more complex process initiated by PAM-con-
taining RONS in actual biological cells must be understood
more clearly in future work.
The RONS-mediated mechanism of selective cancer
cell injuries can be explained in terms of the different sta-
tuses of cancer and normal cells when in the PAM environ-
ment. One possible explanation compared to many cancer
cells is that normal cells may have a higher antioxidant
reserve. Therefore, normal cells are more tolerant to exog-
enous RONS stress, and the issue of the appropriate dose
of PAM treatment is less important. In contrast, cancer
cells have a specific metabolic need. Accordingly, more
aquaporin is expressed in cancer cells than in normal
cells (Yan etal., 2015). Cancer cells with an elevated rate
of RONS production are more vulnerable to the accumula-
tion of intracellular RONS. The molecular level explana-
tion of this phenomenon is also addressed below.
Molecular mechanisms of PAM-induced
apoptosis
The molecular mechanisms associated with the PAM anti-
cancer effect have been addressed in several studies. PAM
function as reactive species donors (specifically RONS), for
inhibition or atviation of survival and proliferation signal-
ing pathways, and are involved strongly in the inhibition
of carcinogenesis. The PI3K/AKT and Ras/MARP pathways
are found to be constitutively active in glioblastoma brain
tumor cells, and after a treatment with PAM, both path-
ways were found to be down-regulated. This may also
explain the selective killing effect of PAM, as PAM types
are expected to attack the signaling pathways that are spe-
cially activated in cancer cells. As these two pathways are
related closely to proliferation for tumor cells and the inhi-
bition of apoptosis, down-regulation of these pathways
could induce apoptosis in cells (Tanaka, 2012).
Reactive species present in PAM can cause damage
to the DNA structure by changing the hydrogen bonds
between the complementary bases in the DNA. This
type of DNA oxidation is also associated with increased
8-hydroxy-20-dexyguanosine formation and the activa-
tion of poly(ADP-ribose) polymerase-1 (PARP-1), which
further results in the intracellular ATP amount decreas-
ing, leading to cell death (Kumar etal., 2016).
0Control NO2
H2O2PAM
**
*
H2O2
+NO
2
50
Cell survival (%)
100
Figure 3:Anticancer activity of NO2
alone, H2O2 alone, both NO2
and H2O2 or PAM on U251SP (human glioma cell line) according to
MTS assays after 24h of incubation.
Here, PAM is prepared by irradiating media with an ultra-high electron
density plasma plume (1016 electrons per cm−3) up to 300s. Obtained
with permission from Kurake etal. (2016). Copyright © Elsevier, 2016.
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8 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
H2O2 from PAM-triggered mitochondria dysfunc-
tion may act as the primary event in the apoptosis signal
pathway. Mitochondria play a pivotal role in cell apopto-
sis by releasing pro-apoptotic factors such as apoptosis-
inducing factor (AIF) and cytochrome c, thus activating
caspase-independent and caspase-dependent pathways,
respectively (Hong etal., 2004). The activation of PARP-1
induces a release of AIF from mitochondria, accompanied
by the formation of poly(ADP-ribose) (PAR) and the deple-
tion of nicotinamide adenine dinucleotide (NAD+). AIF
released from mitochondria shuttle to the nucleus and are
known to trigger chromatin condensation and extensive
nuclear injury. When mitochondria are damaged and the
membrane potential is decreased, the permeability of the
membrane will increase and allow an efflux of AIF, thus
aggravating the translocation of AIF to the nuclei, induc-
ing chromatin condensation and DNA fragmentation and
ultimately cell apoptosis. Adachi and coworkers reported
a mitochondria-dysfunction-mediated caspase-independ-
ent signal pathway in cases of cancer cell injuries by PAM.
The PAM treatment activated PARP-1, induced the forma-
tion of PAR in the cell nuclei, the accumulation of AIF
surrounding the nucleus and the depletion of the total cel-
lular NAD+ amount in cancer cells. However, these injury
effects can be suppressed by a PARP-1 inhibitor, further
confirming that PAM activates PARP-1 and subsequently
induces mitochondrial dysfunction. Moreover, PAM sig-
nificantly increased the number of calcium ions (Ca2+)
and thus induced the endoplasmic reticulum (ER) stress-
mediated apoptosis pathway, as shown by the increased
expression of the ER stress marker C/EBP homologous
protein (CHOP) (Adachi etal., 2015).
Though the complex mechanism networks between
PAM and cell interactions still need to be elucidated, these
findings provide significant insight into the intracellular
molecular mechanism of PAM-mediated cancer cell apop-
tosis, especially with regard to the selective killing effect.
Understanding the molecular mechanism will provide
strong evidence and lead to clinical applications of PAM
in the future.
Role of PAM on three-dimensional
(3D) cancer spheroids, the epithe-
lial mesenchymal transition (EMT)
and metastasis
Judée et al. investigated the anti-proliferative effects of
PAM on HCT116 colon adenocarcinoma tumor spheroids
(Judée etal., 2016). They generated PAM using a pulsed
helium plasma jet in open air with 60–240s of plasma
exposure. Multicellular spheroids were immersed in PAM
at different time intervals (from 15min to 48h). The growth-
inhibiting effect of PAM on these HCT116 spheroids was
evaluated, and it was found to be associated with DNA
damage, leading to cell death and a loss of the multicel-
lular tumor spheroid proliferative region. The spheroid is a
well-known 3D model in in vitro conditions, resembling an
in vivo tumor, and it also plays an important role in many
metastasis processes. DNA damage as observed on the out-
ermost layers of the spheroid is completely dependent on
the plasma exposure dose. Catalase is used in this study to
validate the role of H2O2 in the observed genotoxic effect.
However, the viability of GM637 human fibroblasts was
selectively unaffected after exposure to PAM (Judée etal.,
2016). This study also emphasized the selectivity of PAM to
inhibit the growth of cancerous cells only rather than the
effect on normal human cells. The stability of PAM is also
very important to induce a genotoxic effect, it has been
reported that the activity of PAM can be maintained upon
storage at +4°C or −80°C for up to 7days. The aging of PAM
is also an essential factor for medical applications. The
stability of PAM may be due to the crystallization of H2O2
at a very low temperature, such as below −60°C, to avoid
any decomposition. The genotoxic and viability inhibition
effects induced by PAM are due to the presence of H2O2 or
certain stable species in an aqueous solution; however, the
role of other ROS or RNS, or RONS or other factors, gener-
ated by plasma must also be considered when comparing
PAM types upon a direct plasma exposure. There is also a
need for further research on the level of stability consider-
ing the various chemical characterizations present in PAM
to validate its storage-duration dependent efficacy.
Nofel and coworkers investigated the inhibitory
effects of PAM on head and neck cancerous FaDu cells.
The responses of cells in both monolayers and spheroids
after a treatment with PAM were compared (Nofel et al.,
2017). The PAM and H2O2 effects were compared on FaDu
cells, and their spheroids were assessed by MTT and a
sphere-size detection assay, respectively. They empha-
sized that PAM must be considered as a potentially effec-
tive agent in the treatment of head and neck cancer. They
also indicated that multicellular tumor spheroids are
more valuable model than a monolayer cell culture during
an investigation of the anti-cancer activity of PAM.
Ikeda etal. reported the effects of PAM on the cancer-
initiating cells of endometrioid carcinoma and gastric
cancer cells, which are present in few tumors and which
are mainly responsible for tumorigenesis and metasta-
sis (Ikeda et al., 2018). Cancer-initiating cells are also
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids9
responsible for tumor resistance to chemotherapy by elim-
inating drugs using aldehyde dehydrogenase enzymes,
and they are also resistant to radiotherapy. This study
showed that PAM can induce apoptotic cell death selec-
tively in cancer-initiating cells without affecting normal
cells. A combined treatment with PAM and cisplatin
enhances the apoptotic death of cancer cells as compared
to the effect by PAM or cisplatin alone. An in vivo study
involving a xenograft mice model also demonstrated a
similar cancer inhibitory effect on cancer-initiating cells.
The expected mechanism is related to components of PAM
which may directly inhibit the aldehyde dehydrogenase
activity, thus triggering cancer regression. PAM types are
recommended against cancers; however, it is also impor-
tant to combine them with other chemotherapies or radio-
therapies. This must also be studied in the future. Further
studies of the mechanisms involved are also important,
PAM can be a promising treatment modality, contributing
to a brighter therapeutic outlook, especially when com-
bined with other treatment methods.
PAM can be as efficacious as a direct plasma treat-
ment to induct anti-cancer activity on cancer cells. ROS
and RNS in media or in an aqueous solution play key roles
in the anti-cancer activity of PAM. The efficacy of PAM is
dependent on many factors, such as the plasma exposure
dose, the storage duration, the storage temperature and
the incubation time during the treatment.
Plasma liquid interaction is a very important topic in
the field of plasma medicine because most cells and tissues
are surrounded by body fluids. Mohades etal. reported in
conjunction with measurements of the concentrations of
H2O2 that most stable plasma generated species are known
to have strong biological effects which are generated by
plasma exposure to a culture medium (Mohades et al.,
2015). Plasma pencils were used in this study to prepare
the PAM and to assess its anticancer activity on SCaBER
human bladder cancer cells. Mohades etal. compared the
anticancer effect of PAM with apoptotic-inducing drugs
such as staurosporine and indicated that PAM types can
retain their killing effects for several hours. PAM types
produced by longer plasma exposure times are most effec-
tive, but this effect decreases with time. PAM showed an
incubation-time-dependent effect on cancer cells, but no
immediate effect. PAM produced by 4min of plasma expo-
sure (produced by a plasma pencil) reduced cell viability
by nearly 90%. PAM produced by a plasma pencil can be
stored at room temperature for up to 8h and can be effica-
cious against cancer cells.
In another study, it was reported that the concentra-
tions of the reactive species and consequently the effective-
ness of PAM decrease over time after exposure to plasma
(Mohades etal., 2016a,b). The aging-time-dependent effect
of PAM on the viability of SCaBER bladder squamous cell
carcinoma cells was demonstrated. To assess the effects of
PAM on normal cells, MDCK (Madin-Darby canine kidney)
cells from the normal epithelial tissue of a dog kidney were
treated. The viability of normal MDCK cells was unaffected
at various doses despite the severe killing impact of PAM
on SCaBER cells. In their study, they used both serum-free
and complete media to investigate the role of ferrous-ion-
containing proteins and enzymes on the decomposition of
H2O2 via the Fenton reaction. Serum in cell culture media
contains proteins and metallic compounds such as ferrous
ions, which can destroy H2O2 in PAM. Therefore, we evalu-
ated the H2O2 concentration in a serum-free PAM as well as
a serum-supplemented PAM. The earlier researchers meas-
ured the amounts of hydrogen peroxide at different aging
times after exposure to plasma. The stability of the reactive
species in an aqueous state is one of the most important
issues to determine the effectiveness and self-life of PAM.
This study showed a correlation between the effective-
ness of PAM and the H2O2 concentration, as both decrease
over time. It was shown that complete media (with serum)
reduce the level of H2O2 by 50% in PAM aged for 8h. Other
factors such as the plasma exposure time, the storage
temperature, and the pH of the media are also important
parameters that can influence the stability of the reactive
species induced by PAM.
Takeda and colleagues claimed that the administr ation
of a fluid treated with atmospheric-pressure non-thermal
plasma has attracted much interest as a novel treatment
for cancers, and they demonstrated the therapeutic effect
of PAM against cancer in vivo using a peritoneal metastasis
mouse model (Takeda etal., 2017). For the preparation of
PAM, they considered factors such as the distance between
the plasma source and the medium surface and changes of
the volume of the medium. Wound-healing and adhesion
assays were conducted on two gastric cancer cell lines to
check the effect of PAM on the cell migration and adhe-
sion ability in vitro. It was found that shorter gap distances
between the plasma source and the medium surface and
smaller volumes of the medium enhance the anticancer
activity of PAM. The PAM treatment reduced cancer cell
migration and adhesion. The mechanism of these out-
comes is related to oxidization by oxygen radicals and the
destruction of molecules which adhere to the cell mem-
brane. Peritoneal metastatic nodules were reduced by 60%
with an intraperitoneal injection of PAM in a mouse model.
It was concluded that plasma-activated liquids may repre-
sent a novel treatment method against peritoneal metas-
tases in gastric cancers. It is also important to note that
the detailed work on the inhibitory effect of PAM, the use
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10 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
of other plasma liquid treatment modalities (e.g. simple
liquids such as water or saline) and safety studies of PAM
on humans must be carried out in the future.
Nakamura etal. demonstrated the anti-cancer effects
of PAM in an animal model reflecting pathological con-
ditions and the accompanying mechanisms (Nakamura
et al., 2017). They investigated the effect of PAM on the
metastasis of ovarian cancer ES2 cells in vitro and in vivo.
They demonstrated that cell migration, invasion and adhe-
sion were suppressed by PAM at a certain PAM dilution
ratio, at safe doses. The molecular mechanisms were also
assessed for these outcomes using PAM. It was found that
MMP-9 (critical for cancer cell mobility, EMT and meta-
stasis process) was reduced and that the MAPK pathway
was activated by the inhibition of the phosphorylation
of JNK1/2 and p38 MAPK after the treatment (Figure 4).
Kaplan-Meier survival analysis results showed that the
mice model from the PAM-treated group had a better sur-
vival rate. This report on clinical predictions from a pre-
clinical in vivo study can be very important with regard to
the development of a medical strategy for ovarian cancer
treatments involving the use of PAM.
Anticancer effect of other
plasma-activated liquids
Research on other plasma-activated liquids such as
plasma-activated solutions (PAS) or plasma-stimulated
solutions (PSS) is a steadily emergent area in plasma
medicine. For this purpose, researchers have considered
all types of solutions or buffers which are already used
clinically. Recently, researchers also made new claims that
their PAS or PSS is effectively administrable to humans;
however, there are no relevant clinical data to show the
advantage of their activated solutions over others to
support their claim. Tanaka etal. demonstrated a tumo-
rigenicity inhibition effect of plasma-activated Ringer’s
lactate solution (Tanaka etal., 2016). A plasma treatment
of lactate generates acetyl and pyruvic acid-like groups can
show anticancer effects. It is expected that plasma gener-
ates acetyl and pyruvic acid-like groups in acetic acid Ring-
er’s solution. A study of plasma-activated lactated Ringer’s
solution (PAL) demonstrated the antitumor effects of PAL
in vitro and in vivo (Sato etal., 2018). It was demonstrated
that the intraperitoneal administration of PAL can be a
more appropriate therapeutic option for cancer and peri-
toneal metastases inhibition. Another recent report con-
ducted a comparison between plasma-stimulated media
(PSM) and PSS (using a buffer solution) on pancreatic and
brain cancer cells (Yan etal., 2017). They showed that PSM
and PSS can both have specific anticancer effects depend-
ing on the cancer cell type. In addition, the toxicity of PAS
or PSS on cancers can be significantly improved by con-
trolling the dilution of the solutions.
Effect of PAM on non-cancerous
cells
Previous reports have shown that PAM have anti-tumor
effects on various types of cancerous cells (Tanaka etal.,
2014, 2015a,b). PAM provides different advantages, such
as the isolation of the effects of chemical species in acti-
vated media from the direct effects of other agents in the
plasma, such as charged particles, UV radiation and heat.
PAM can also be stored for later use. These discoveries
have widened the applications of cold-plasma-induced
therapy, in which indirect plasma in the form of PAM may
be a promising tool for use with cancer therapies that are
associated with unwanted side effects due to damage to
normal cells and healthy tissue. Hence, it is very impor-
tant to understand the interaction between plasma and
normal cells in relation to other medical uses. Earlier
studies found that normal cells are more resistant to oxi-
dative stress induced by a plasma treatment than cancer
cells; hence, a plasma treatment can be used to treat
certain cell types (Iseki et al., 2012; Wang et al., 2013;
Mohades et al., 2016a,b). The absence of skin damage
induced by the plasma treatment was reported by Fridman
Figure 4:Mechanisms of the intraperitoneal anti-metastatic effect
of PAM.
Oxidative stress in ES2 cells down-regulates MMP-9 expression
via MAPK pathway inhibition, alleviating cancer cell adhesion,
migration and invasion onto the mesothelial cell lining in the
peritoneal cavity (Nakamura etal., 2017).
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids11
and colleagues (Fridman etal., 2008), who noted that the
selective effect of a plasma treatment is highly dependent
on the dose (time) of plasma exposure. Therefore, normal
cells can withstand a moderate level of oxidative stress up
to a certain limit, but a longer exposure time can induce
severe inevitable damage (Graves, 2012). In this section,
we exploit the effects of PAM on non-cancerous cells and
its various medical applications as used presently.
PAM treatments are also responsible for the suppres-
sion of many non-cancerous cells, such as MDCK cells
(canine kidney epithelial cells) and SCaBER cells due to
the concentration of hydrogen peroxide generated in the
media (Mohades etal., 2016a,b). A decrease in the cellular
viability, morphology and migration was revealed 2days
after a PAM treatment in MDCK cells. Immuno-staining of
the Ki67 localization in MDCK nuclei confirms the inhi-
bition of cellular proliferation (Mohades et al., 2017). A
co-culture of liver cancer cells (HepG2) and normal liver
cells (L02) in a system with PAM produced by a plasma
jet with different time intervals showed a decrease in
adherence with an increase in the treatment time in a
mono-culture system. This indicated that the optimum
dose of PAM (10min plasma treatment) can kill cancer
cells while causing less damage to normal cells in the co-
culture system. Investigations showed that non-adherent
cancer cells are in apoptosis rather than necrosis states
without significant changes in the pH values of the PAM
(Duan etal., 2017). The cause of this can be attributed to
the increase in the concentrations of H2O2 (594 μ) and
NO (29 μ) at a plasma treatment time of 10min. The cat-
alytic-iron-associated cellular proliferation of endometri-
otic glandular cells was also reported, most likely induced
by the PAM treatment (Ishida etal., 2016). Therefore, PAM
types prevent the progression of endometriosis in murine
models (Ishida etal., 2016). PAM types are also known to
suppress choroidal neovascularization in mice, which is
a new therapeutic concept related to age-related macular
degeneration (Ye etal., 2015).
Role of PAM in blood coagulation
and as regenerative medicines
The facilitation of blood coagulation by non-thermal
plasma-generated water is a novel method that is espe-
cially effective when used to stop the oozing of blood in
surgery (Miyamoto etal., 2016). Plasma-generated water
induced eosinophilic fibrous membrane-like structures,
while the natural coagulation process usually contains
erythrocytes for healing purposes (Ikehara etal., 2013).
The inflammation recovery process after a treatment
with non-thermal plasma water or a thermal coagulator
was visualized using radiopharmaceutical, 2-deoxy-2-[18F]
fluoro-D-glucopyranose (18F-FDG), and it was shown that
the former is less inflammatory (Ueda etal., 2015). Elec-
tron microscopic analyses revealed that fragmented fibro-
blasts were seen in electrocoagulation-treated skin and
not in plasma-treated water skin (Akimoto etal., 2016).
PAM types act as a useful tool for the selective elimina-
tion of undifferentiated human-induced pluripotent stem
cells (hiPSCs) from a population of differentiated cells,
and they act as a type of regenerative medicine during
a cell transplantation therapy (Matsumoto et al., 2016).
Low-dose plasma-treated water can promote cell growth,
while high-dose plasma-treated water induces apoptosis
or necrosis, which may reflect the dose-dependence of
oxidative stress (Kalghatgi etal., 2010; Toyokuni, 2016).
From the perspective of cardiac disease, the perfusion of
non-thermal plasma-treated water resulted in lower blood
pressure and an increase in the nitrous oxide concentra-
tion in the abdominal aortas of rats (Tsutsui etal., 2014).
Role of PAM in antioxidant activity
At present, correct dieting principles and paying attention
to what we eat in order to stay healthy are very important.
The bulk of what we eat, such as fruit and vegetables,
are 90% water, while fish and meat are about 70% water.
Vitamin C is the main antioxidant present in staple diets,
and it rapidly diminishes with age. Hence, the reduction
potential of vitamin C decreases (Harrison, 2012). For
this reason, it is necessary to take vitamin C in the form
of a dietary supplement. Studies at the genomic level
showed protective and antioxidative roles of cold plasma
in aqueous media (Kurita etal., 2014). Carbohydrates, the
main component of fruit and vegetables, have a molecular
mass of 180 Da, whereas water has a much lower molecu-
lar weight of 18 Da. PAM types consist primarily of water
and have a high reduction potential (−250mV to −300mV),
making them superior scavenging agents of active oxygen
(Lotfy, 2016). A nuclear magnetic resonance (NMR) analy-
sis found that tap water and well water consist of clusters
of 10–13 H2O molecules. The electrolysis of water in PAM
makes these species slightly alkaline while also reduc-
ing these clusters to about half their normal size, i.e. five
to six water molecules per cluster (Santos et al., 2013).
Due to plasma treatment electrolysis in a liquid medium,
more active hydrogen molecules-ORP are generated, with
lower surface tension than regular tap water. The lower
surface tension makes PAM (alkaline ionized water) easier
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12 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
to absorb via cellular osmosis. PAM quickly permeates the
body and blocks the oxidation of biological molecules by
donating its abundant electrons to active oxygen, ena-
bling biological molecules to replace themselves naturally
without damage caused by oxidation, possibly leading to
diseases. The antioxidant effects of PAM on fibroblasts
against cellular injury due to the high dose of H2O2 as an
oxidative stress inducer were also reported in studies that
activated the Keap1-Nrf2-ARE signaling pathway (Horiba
etal., 2017).
PAM as an antiviral and medical
disinfectant
Recent studies of different viruses showed that PAM has the
potential to inactivate the Newcastle disease virus (NDV),
which causes a deadly infection in birds but which has
mild effects on humans. For the treatment of this dreadful
disease, PAM (H2O), PAM (NaCl) and PAM (H2O2) as an anti-
viral solution were used to eradicate or inactivate NDV at an
appropriate ratio, as verified by an embryo lethality assay
(ELA) and a hemagglutination (HA) test (Su etal., 2018).
The possible mechanism of PAM inactivation against NDV
is RONS, including short-lived OH˙ and NO˙ and long-lived
H2O2 detected in PAM, which may change the viral morphol-
ogy, degrade viral proteins, and destroy the RNA structure,
thus resulting in the inactivation of the virus.
Researchers globally are testing how PAM compares to
other disinfectants, such as alcohol, to reduce infections,
as 7% of hospitalized patients acquire a new infection
during their treatment (Raja Danasekaran and Annadurai
2014). PAM obtained by exposing sterile distilled water
with a gliding arc plasma plume can inactivate bacterial
(Hafnia alvei) and yeast cells in their planktonic and adher-
ent forms (Kamgang-Youbi et al., 2007). The efficiency of
any disinfection method depends on a number of factors,
including both abiotic factors and biotic factors. Inactiva-
tion of sessile bacteria (Gram-positive and Gram-negative)
by a PAM treatment is well acknowledged (Stewart and
Costerton, 2001; Patel, 2005; Kamgang-Youbi etal., 2007)
in food-borne pathogens (Kayes et al., 2007). The pres-
ence of H2O2 and an acidic pH of nitrite and nitrates in
PAM when exposed to the gliding arc taken together may
be mainly responsible for the inactivation capacity of PAM
(Burlica etal., 2006). However, PAM is highly resistant to
yeast and oxidizing radicals, H2O2, and acidified nitrite
has been found to be less efficient vs. yeast than vs. bac-
teria (Guyader etal., 1996; Weller et al., 2001; King etal.,
2006).
PAM in water treatment and
processing applications
Plasma-treated water is presently starting to be applied in
advanced oxidation processes (AOP). It is well established
that plasma in water contains numerous chemically active
species, such as OH radicals, O radicals and H radicals,
which have strongly oxidized agents (Bruggeman and
Leys, 2009). PAM produced by a high impulse current can
form radicals in a medium, a process which is presumably
effective at removing chlorine disinfection by-products
from water supplies and which can serve as a substitute
for drinkable water. PAM procured by this method can
easily be used for waste water treatments, sterilization
and other chemical processes.
The role of PAM in dentistry
Applications of cold plasma for the sterilization of dental
and medical equipment as an alternative to traditional
sterilization methods will be very safe and cost effective
(Morris etal., 2009). Morris etal. studied the effect of cold
plasma (direct and indirect) on bacterial cultures. They
evaluated Geobacillus stearothermophilus and Bacillus
cereus and their interactions with cold plasma. It has been
suggested that the plasma effect produces greater damage
to Gram-negative bacteria than to Gram-positive bacteria
(Laroussi et al., 2003). Geobacillus stearothermophilus
(Gram-positive), very resistant to high pressures, is used
as an indicator of sterilization methods. Bacillus cereus
(Gram-positive) is commonly associated with periodon-
tal disease and food poisoning (Beuchat etal., 1997). An
experimental study carried out by Morris etal. revealed
that two Gram-positive strain bacterial cells were inacti-
vated effectively, whereas G. stearothermophilus spores
were not significantly decreased. Moreover, this effect was
seen at a higher temperature by an indirect rather than a
direct application of plasma.
The World Health Organization (WHO) considers per-
iodontal diseases and caries as a major reason for tooth
loss and as a global oral health issue (Peterson, 2003).
The main culprits behind this are bacterial strains and
pathogens, which must be systematically eradicated.
Good oral health and the use of mouthwash represent a
good combination. Most commonly, chlorhexidine (CHX)
is used as a mouthwash, but it can cause tooth stains and
erosion. Hence, alternatives need to be found. Li et al.
evaluated the antimicrobial effects of PAW as a mouth-
wash (in an in vitro study) (Li etal., 2017b).
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids13
The study was carried out in vitro using Streptococcus
mutans, Actinomyces viscosus and Porphyromonas gingi-
valis. Streptococcus mutans is the main cause of dental
caries (Koban etal., 2011), A. viscosus is responsible for
plaque formation, and P. gingivalis is a periodontal agent.
It is also a major agent responsible for chronic periodon-
titis (Andrian et al., 2006). PAW (water treated by cold
plasma) when obtained by the exposure of distilled water
to gliding arc discharges (Kamgang-Youbi etal., 2008) can
generate radical species (OH/NO) without any dangerous
side effects of the direct plasma jet or UV radiation. The
experiment in that study indicated the successful inac-
tivation (included the distortion of the morphology and
cytoplasmic shrinkage and the leakage of proteins and
DNA) of S. mutans, A. viscosus and P. gingivalis using
PAW. The results suggested (Figure 5) that PAW has the
potential to be utilized as an agent in a new type of
mouthwash to kill oral bacteria (Li etal., 2017b).
The usage of PAM/PAW in dentistry is still the subject
of numerous studies. Research is being carried out for
tooth whitening procedures as well, but no commercial
products are available for usage. White teeth are estheti-
cally appealing to people, and tooth bleaching has long
been used in the dental field. However, the usage of PAW/
PAM as a medium for tooth whitening due to its efficiency,
safety and biosecurity makes it a potentially useful
method for clinical tooth whitening procedures. Currently,
research is ongoing to assess the viability of this technique
(Kang, 2016; Cheng etal., 2017).
Shi et al. studied the activation of signal pathways
when oral cancer cells were exposed to PAM (Shi et al.,
2017). Although cold atmospheric pressure plasma is
being increasingly used as a cancer treatment method,
problems related to convenient storage and its infiltration
capacity have resulted in the development of alternate
plasma treatment methods such as PAM. NO, H2O2 and
NO2
– NO3
anions are the commonly found ROS species
in PAM; these are relatively long-lived secondary prod-
ucts, unlike direct cold atmospheric plasma (CAP), which
generates short-lived species (Chauvin etal., 2017). These
long-lived RONS species are responsible for the cytotoxic
effects of PAM. With respect to cancer cells, PAM types
allow for the selective treatment of specific target cancer
cells that are not reachable by gaseous applications of
plasma (Chauvin etal., 2017; Shi etal., 2017). In a study
by Utsumi and coworkers it was found that PAM activa-
tion has anti-tumor effects on chemo-resistant cells both
invitro and in vivo (Utsumi etal., 2013). In work by Shi etal.
(2017), RNA-sequencing and immunology were used to
identify the transcriptomic changes in an oral squamous
cell carcinoma cell line (SCC-15) when treated with PAM.
KEGG mapping showed enriched signaling pathways, in
this case the ‘p53 pathway’, ‘hippo pathway’, ‘TNF-path-
way’, ‘AGE-RAGE pathway’ and the ‘FOX pathway’, but the
p53 pathway was the most significant of all. PAM activa-
tion had no effect on the p53state of mRNA or the protein
levels, but genes related to the p53 pathway were acti-
vated. Liebermann etal. concluded that plasma-induced
Power
supply
Gas
Electrodes
Plasma
Distilled
water
Preparation of plasma
activated water (PAW)
Bacterial strains and culture
P. gingivalis
Addition of bacterial
culture to PAW
(each culture was added in a
separate container)
Distortion of
morphology due to
PAW
Inactivation of
bacterial cells
Interaction
with healthy
cells
Plasma
activated
water
IV.III.
II.I.
Plasma
activated
water
A. viscosus
S. mutans
Figure 5:Effect of PAW on bacterial strains related to dental diseases.
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14 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
cell death could be a p53-dependent or p53-independent
process (Liebermann etal., 1995).
The disinfection and sterility of dental units is a
problem due to the presence of pathogens in the biofilms
within the dental unit waterlines. Improper disinfection
methods can cause remnants of the biofilm to be present,
possibly leading to bacterial multiplication. Dental unit
waterlines can be disinfected using various methods, such
as disinfectants and ICX (Bowen etal., 2015). PAW/PAM is
also being tested for this purpose. Pan etal. used PAW on
dental waterlines with Enterococcus faecalis biofilm. The
results indicated the inactivation of the bacteria within
5min of the treatment due to the presence of RONS within
the PAW (Pan et al., 2017). More such studies must be
carried out in the future to establish PAW as a disinfectant
for dental equipment.
Sterilization of microorganisms
byPAM and PAW
Despite the ongoing food safety measures in the US,
foodborne illnesses continue to be a substantial health
burden. The 10 US sites of the Foodborne Disease Active
Surveillance Network (FoodNet) monitor cases of labo-
ratory-diagnosed infections caused by nine pathogens
transmitted commonly through food. In 2017, FoodNet
reported 24484 infections, 5677hospitalizations and 122
deaths. When compared with 2014–2016, the 2017 inci-
dence of infections with Campylobacter, Listeria, non-
O157 Shiga toxin-producing Escherichia coli, Yersinia,
Vibrio and Cyclospora increased (Marder et al., 2018).
Most foodborne illnesses can be prevented by reducing
the contamination of microorganisms in food. The search
for novel techniques for microbial decontamination is
currently the subject of a considerable number of investi-
gations. Non-thermal plasma is a new approach to micro-
biological safety while maintaining the sensory attributes
of the treated foods (Xu et al., 2016). It involves exposing
food to ionizing radiation (such as charged particles, EF,
UV photons or reactive species) to disinfect the microbes
while ensuring the safety of the products. Previous work
has demonstrated that non-thermal plasmas can effi-
ciently disinfect a wide range of microorganisms, includ-
ing bacteria, fungi, viruses, bacterial spores and biofilms
(Kolb et al., 2008; Pan et al., 2013). ROS are the major
bactericidal agents, and they cause damage to DNA and
proteins in microbial cells (Joshi etal., 2011). Non-thermal
plasma is also known to be highly effective when used to
reduce harmful bacteria and eliminate toxins in fruits,
vegetables and various meat stuffs, while preserving the
fresh taste, aroma, texture, wholesomeness and nutri-
tional content of the food (Baier etal., 2013; Pankaj etal.,
2014).
Cold plasma is a mixture of electrons, ions, free
radicals and excited and neutral molecules. It has been
proven to react with water, implying that PAW possesses
the ability to inactivate microbial cells (Kamgang-Youbi
et al., 2008; Naïtali et al., 2010; Oehmigen etal., 2010;
Zhang etal., 2013). It is generally agreed that the bacte-
ricidal activity of PAW derives from the synergistic effects
of a high positive oxidation reduction potential (ORP) and
low pH. Among the various reactive chemical species in
PAW, H2O2 are the main types of ROS; however, OH, O and
O3 also indirectly contribute to the ORP, as they can react
and form stable and toxic molecules. Moreover, RNS must
be considered to result in the high ORP; examples include
NO and its derivatives formed with water, including NO2
,
NO2
, and ONOOH (Laroussi, 2005; Dobrynin etal., 2009;
Oehmigen etal., 2011; Lukes etal., 2012, 2014; Van-Gils
et al., 2013). Meanwhile, the production of RNS also
plays a dominant role in the acidification of PAW. Recent
research has reported that PAW can also efficiently inac-
tivate a wide variety of microorganisms. Various plasma
sources are used to activate water, including direct current
(DC), low-frequency discharge, radio frequency discharge,
pulsed coronas, DBD, atmospheric pressure plasma jets
and microwave discharge (Laroussi, 2002; Fridman etal.,
2005; Moreau et al., 2008; Park et al., 2012). Currently,
research on the impact of the pH and of H2O2 on the pro-
gress of PAW disinfection has highlighted the importance
of ROS in PAW solutions (Naitali et al., 2010; Oehmigen
etal., 2010). Atmospheric-pressure plasma jets have been
used to activate water for the disinfection of bacteria such
as B. subtilis (Sun etal., 2012), S. aureus (Zhang etal., 2013,
2016; Shen et al., 2016) and Pseudomonas aeruginosa
(Van-Gils etal., 2013).
Recently, there have been reports on a plasma jet that
was used to activate water for the inactivation of bacte-
ria and fungi from mushrooms of ROS in PAW solutions
(Naitali etal., 2010; Oehmigen etal., 2010). Atmospheric-
pressure plasma jets were also used to activate water for the
disinfection of bacteria such as B. subtilis (Sun etal., 2012)
and Staphylococcus aureus (Zhang etal., 2013, 2016; Shen
etal., 2016) and (Agaricus bisporus) (Xu etal., 2016). More-
over, Li etal. (2017b) reported a novel mouthwash which
was assessed in vitro using cold-plasma-jet-activated water.
Three representative oral pathogens (S. mutans, A.visco-
sus and P. gingivalis) were treated with PAW. Scanning and
transmission electron microscopy images showed that the
normal cell morphology was changed by varying degrees
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids15
after a treatment with PAW (Figure 6). This report suggests
that PAW has potential for use as a novel antimicrobial
mouthwash. In addition, micro-pulsed DBD was used to
activate water for the decontamination of E. coli (Traylor
etal., 2011), Candida albicans and S. aureus (Ercan etal.,
2013; Laurita etal., 2015).
Moreover, Kamgang-Youbi et al. (2008) reported the
efficacy of a plasma chemical solution obtained by the
activation of water with gliding electric discharges for the
disinfection of planktonic and adherent cells of Staphylo-
coccus epidermidis, Leuconostoc mesenteroides (as models
of Gram-positive bacteria), H.alvei (a Gram-negative type
of bacteria) and Saccharomyces cerevisiae (as a yeast
model). PAW could disinfect adherent cells better than
planktonic cells in the case of bacteria. When comparing
bacteria and yeast cells, PAW was more effective for bac-
teria than for yeast. The efficacy of PAW depends on the
type of microorganism and the reactive species produced
in the PAW. The reactive species (ROS and RNS) produced
in PAW also depend on many factors, such as the plasma
working gas, the discharge type, the treatment time, the
storage time and the chemical composition of the sur-
rounding environment.
Effects of PAW on microbial cells
The action of atmospheric pressure plasma water-based
liquids and distilled water involves changes in their
characteristics, mainly the pH and electric conductiv-
ity, to acquire important oxidative potentials (Vlad and
Anghel, 2017). Depending on the nature of the discharge
gas (argon, helium, air, oxygen, nitrogen or their mix-
tures), ROS and reactive nitrogen species are generated
in the plasma core or in the plasma-liquid contact zone,
after which they are dissolved in the liquid (Lukes etal.,
2014; Vyhnankova etal., 2014; Jablonowski and Woedtke,
2015; Laurita et al., 2015; Rumbach et al., 2015; Gorba-
nev etal., 2016; Janda et al., 2016; Rehman et al., 2016;
Shang etal., 2016). Some of them are long-lived species
while the others are short-lived species (Liu etal., 2016).
They are responsible for a large variety of applications of
plasmas in contact with liquids, mainly in the bio-med-
icine field and for the reduction of environmental pollu-
tion ( Kamgang-Youbi etal., 2008, 2009; Jablonowski and
Woedtke, 2015; Laurita etal., 2015; Janda etal., 2016). For
microbial cells, ROS such as O, OH and 1O2 are the key
inactivation agents in plasma direct inactivation, and
plasma-induced oxidative stress is believed to cause cell
damage and death (Laroussi and Leipold, 2004; Nagatsu
etal., 2005; Kim etal., 2009; Helmke etal., 2011; Ma etal.,
2012; Zhang etal., 2012). Water activated by non-thermal
plasma near room temperature and at atmospheric pres-
sure will generally create acidic (pH approx. 2–3) solutions
that contain H2O2, NO2 and NO3 anions, as well as other
species ( Oehmigen et al., 2010). Such an acidic solution
can effectively kill bacteria in a suspension (Kamgang-
Youbi etal., 2007, 2008). If the pH exceeds approximately
3–4, the antibacterial effectiveness is known to drop sig-
nificantly (Oehmigen etal., 2010).
Furthermore, Zhang etal. (2016) described steriliza-
tion mechanisms of PAW for S. aureus cells (Figure 7).
Large amounts of RONS in PAW could be produced by
air plasma, leading to the acidification of PAW. The most
reactive and toxic species among all RONS, especially
OH, could initiate lipid peroxidation of the lipid bilayer in
the cell membrane by abstracting a hydrogen atom from
a methylene group, thus resulting in the cross-linking of
the fatty-acid side chain to form transient pores in the cell
membrane, followed by cell permeabilization and depo-
larization of the cell membrane potential. Intracellular
RONS can accumulate through two pathways. The first is
that by which RONS produced by plasma extracellular can
move into the cell by active transport across the bilayer
or the transient pores in the cell membrane. The second
is that by which external oxidative stress can also induce
S. mutans
A
B
C
D
A. viscosus P. gingivalis
Figure 6:Scanning electron microscopy (A, B) and transmission
electron microscopy (C, D) images of Streptococcus mutans,
Actinomyces viscosus and Porphyromonas gingivalis before (A, C)
and after (B, D) a treatment with PAW.
The red arrows indicate the obvious surface morphology changes
after the PAW treatment compared to the control group. Taken with
permission from Li etal. (2017b). Copyright ©Wiley-VCH Verlag
GmbH and Co. KGaA, Weinheim, 2017.
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16 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
oxidative stress in the cell, thus increasing the intracel-
lular RONS. Meanwhile, a large amount of protons (H+)
in PAW can also flow into the cell via the destroyed cell
membrane, consequently decreasing the intracellular pH
(Figure 7). Intracellular RONS can not only oxidize DNA,
causing the fragmentation of DNA, but can also react with
proteins, lipids and carbohydrates, leading to the altera-
tion of the molecular structure and the chemical bonds.
More importantly, excess intercellular RONS and an
extremely low pH would destroy the redox and pH homeo-
stasis in the cell, ultimately resulting in physiological dys-
functions and cell death.
Role of PAW in plant biology
Ensuring the food security of the ever-growing human
population is the prime task for agricultural scientists.
Worldwide crop production must increase two-fold in
order to fulfill the demand of approximately the 9.6 billion
people who will inhabit the earth in 2050 (United Nations,
2015). However, various physical, biological and anthro-
pogenic factors reduce crop production, representing the
major issues to achieve food security. Biotic and abiotic
types of stress cause a 25–50% reduction in the crop yield
(Acquaah, 2007; Savary etal., 2012). At present, various
approaches, such as the use of pesticides and fungicides,
molecular breeding, genetic engineering and nanotech-
nology are used to manage abiotic and biotic stress. These
approaches are cost-intensive, time-consuming and have
several serious side effects.
Cold atmospheric plasma treatments are emerging
as a cost-effective and eco-friendly tool for enhancing
the plant defense response towards the biotic and abiotic
factors. Cold atmospheric plasma treatments induce and
increase the level of reactive oxygen/nitrogen species in
plants, having both noxious and growth-inducing effects
on plants. A high dose and a longer time treatment of cold
atmospheric plasma have toxic effects and are used to
inactivate pathogens, whereas lower doses and a shorter
time of exposure of cold atmospheric plasma induces
fewer ROS, which have growth-inducting effects.
Over the past few decades, various studies have
been reported on the use cold plasma treatments in agri-
culture. Cold plasma treatments are used either directly
(direct exposure to cold plasma) or indirectly (cold-
plasma-treated water or solution exposure) in agriculture
( Thirumdas, 2018). In agriculture, cold-plasma-treated
water can be produced by two methods: (1) The discharge
of a high electric voltage or current in water, and (2)
through the interaction of gas-phase plasma-generated
free radicals and water molecules. In the first method, pri-
marily ·OH radicals are produced, whereas in the second
method, OH, NO, NO2, NO3 and H2O2 are also produced
(depending upon the flow gas) in water (Horikoshi and
A RONS and H+
generated in PAW
NO·
Normal state Physiological dysfunction
pHi
Oxidation RONS
RONS
D damaging
intracellular redox
and pH homeostasis
+ BSA, RONS
RONS
RONS
PAW
PAW
PAW
RONS
H
+
H
+
H+
H+
H
+
H+
NO·
NO·
NO·
NO·
NO·
OH·
OH·
OH·
OH·
OH·
H+
B
Forming transient pores and drop of
∆ψ
via lipid peroxidation initiated by RONS in PAW
C RONS and
H+ flowing into
cell across the
transient pores
BSA
Normal protein
Oxidized protein
Lipid peroxidation
Transient pore
DNA fragments
Genomic gene
∆ψ
Figure 7:Schematic diagram of the plasma-induced apoptosis process divided into four stages.
(A) RONS generated in PAW and acidification of PAW by a plasma treatment of water. BSA can decrease RONS in PAW by reacting with
them; (B) cell permeabilization and depolarization of the cell membrane potential caused by RONS in PAW reacting with a lipid bilayer; (C)
accumulation of intracellular ROS and a decrease in the intracellular pH; and (D) DNA breakage, even with physiological dysfunctions after
disturbing the intracellular redox and pH homeostasis (Zhang etal., 2016). Copyright © (2016) American Chemical Society.
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N.K. Kaushik etal.: Biological application of plasma stimulated liquids17
Serpone, 2017). These RONS, such as H2O2, ammonium
(NH4
+), NO, NO2 and NO3 ions, have positive effects on
plant germination and growth. NH4
+, NO2 and NO3 ions
serve as sources of nitrogen and enhance plant growth,
whereas H2O2 improves the germination efficiency of
plants (Judée etal., 2018).
Significantly, research done in the area of plasma
applications in agriculture suggests that plasma treat-
ments are effective when used to control plant disease,
for seed decontamination, to instill resistance to abiotic
stress, to improve seed germination and plant growth and
for postharvest disease control.
PAW in seed germination
A plasma treatment of water produces H2O2 by a reaction
between OH and excited water molecules (Maheux etal.,
2015). H2O2 has prime roles in the breaking of seed dor-
mancy and in germination activation (Ismael etal., 2015).
In different seeds, different concentrations of H2O2 are
needed to break the dormancy and induce germination,
varying from 30 μ to 20m (Barba-Espín et al., 2012;
Naim, 2015). Judée etal. 2018 observed that the H2O2 con-
centration varies from 0.3 to 1.85mmol/l with an increase
in the exposure time of the plasma treatment to water.
H2O2 concentrations of 30 μ and 0.7m are effective for
the seed germination of cow peas and coral lentils.
PAW application in plant growth
The most prominent application of PAW is to enhance
plant growth. Takaki etal. (2013) reported that Brassica
rapa irrigated with PAW had a higher nitrogen content
in leaves, a larger leaf surface area and a greater dry
weight as compared to its non-irrigated counterpart.
Sivachandiran and Khacef (2017) observed that tomato
plants treated with PAW had better growth profiles then
untreated plants. They also suggested that PAW contain
higher amounts of NO3 ions, which act as a fertilizer and
help in the germination and growth of plants. In PAW-
treated plants, the augmentation in the growth and germi-
nation of plants is due to the synergetic effect of H2O2 and
NO (Zhang etal., 2017).
PAW role in postharvest disease
Postharvest diseases cause significant losses in crop
productivity. Plant pathogenic fungi such as Penicillium
spp., Aspergillus spp., Fusarium spp., Botrytis cinerea,
Monilinia spp. and Colletotrichum spp. cause significant
losses in crops due to the wide range of the host (Barkai-
Golan, 2001; Tripathi and Dubey, 2004; Narayanasamy,
2008). In recent years, agriculture scientists have focused
mainly on the development of chemical-free approaches
for the control of postharvest diseases at the commercial
level. Plasma treatments are emerging as a viable solu-
tion with which to manage postharvest diseases (Siddique
et al., 2018). The antimicrobial activity of PAW remains
for several days (Traylor etal., 2011) and can be used for
the inactivation of postharvest fungi. Laurita etal. (2015)
successfully reported the inactivation of C. albicans and
S. aureus using PAW. The pathogenic bacterial load was
reduced by 1.4–3.7 log on strawberries after 15 min of a
treatment with PAW (Ma etal., 2015). Another successful
attempt was made by Ouf etal. in 2016. They used cold
plasma to reduce the fungal loads of Aspergillus niger,
Alternaria alternata and Penicillium italicum in the wash
water of strawberries, cherries and red grapes. Ma etal.
(2016) proposed that the effectiveness of PAW increases
with an increase in the duration of the exposure of water
to CP during the PAW generation process. They also sug-
gested that a PAW treatment of Chinese bayberry can
control fruit decay and maintain the quality and taste of
this food.
Future perspectives
Although there have been significant advances recently
in the area of PAM/PAW research, many questions remain
unanswered. Investigations of the complexity of PAM solu-
tions to elucidate the nature and time-dependent con-
centration profiles of the species are important topics for
further studies. The time-dependent stability of PAM may
be correlated with the interaction of the reactive species
and the chemical constituents present inside the media
and the related natural decomposition. More research on
plasma-liquid interactions related to reactive species and
their chemistry is warranted in the future to explain the
overall biological effect induced by PAM. It is also impor-
tant to determine the effects of plasma on various types of
solutions other than media or water. Recently, a research
group at Nagoya University reported the effect of PAL
and plasma-activated acetic acid Ringer’s solution (PAA)
on cancer cells. However, more detailed studies of PAS or
PSS should be conducted in the future using spectroscopic
and NMR analyses with relevant biological mechanisms.
Further dilution of plasma-treated solutions also must be
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18 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
considered by future researchers in assessments of sig-
nificant anticancer effects. Thus, computational tools can
be used to predict the generation or synthesis of chemical
compounds in liquid solutions using non-thermal plasmas
by controlling reactive species or dilutions of solutions.
It is also important to investigate the role of PAM further
with regard to the detachment of cancer cells in vitro and
in vivo, as PAM-induced detached cells may be responsi-
ble for cancer metastasis in the human body. Furthermore,
the route of the safe administration of PAM or PAW, or PAS,
has not been established in humans yet; therefore, phar-
macokinetic and pharmacodynamic studies are needed
to make them more practical indirect plasma treatment
modalities. Alternative applications such as the activa-
tion or differentiation of immune cells, stem cells and for
wound healing can be possible uses of PAM with short
plasma activation times. Moreover, a simple and promis-
ing dental application of PAW as a mouthwash to inhibit
the growth of oral pathogenic microbes must be supported
with biosafety studies of PAW on normal oral tissue.
Finally, for more detailed research on PAM, PAW, and PAS
for a sustainable tomorrow related to regenerative medi-
cine, cancer, dental, sterilization and agriculture topics are
needed to prove their potential and safe applications.
Acknowledgment: The presented work was supported by
a grant from the National Research Foundation of Korea
(NRF), which is funded by the Korean Government, Min-
istry of Science, ICT and Future Planning (MSIP), Funder
Id: 10.13039/501100003725, NRF-2016K1A4A3914113 and
NRF-2016R1C1B2010851 and as well as supported by TBI-
V-1-234-VBW-081. This work was also supported by Kwang-
woon University in 2018 and Ministry of Trade; Industry
and Energy grant No. 20131610101840.
References
Acquaah, G. (2007). Principles of Plant Genetics and Breeding
(Chichester, UK: John Wiley & Sons, Ltd.).
Adachi, T., Tanaka, H., Nonomura, S., Hara, H., Kondo, S., and Hori,
M. (2015). Plasma-activated medium induces A549 cell injury
via a spiral apoptotic cascade involving the mitochondrial-
nuclear network. Free Radic. Biol. Med. 79, 28–44.
Akimoto, Y., Ikehara, S., Yamaguchi, T., Kim, J., Kawakami, H.,
Shimizu, N., Hori, M., Sakakita, H., and Ikehara, Y. (2016).
Galectin expression in healing wounded skin treated with low-
temperature plasma: comparison with treatment by electronical
coagulation. Arch. Biochem. Biophys. 605, 86–94.
Andrian, E., Grenier, D., and Rouabhia, M. (2006). Porphyromonas
gingivalis-epithelial cell interactions in periodontitis. J. Dent.
Res. 85, 392–403.
Aruoma, O.I. (1998). Free radicals, oxidative stress, and antioxi-
dants in human health and disease. J. Am. Oil Chem. Soc. 75,
199–212.
Attri, P., Kim, Y., Park, D., Park, J., Hong, Y., Uhm, H., Kim, K.,
Fridman, A., and Choi, E. (2015). Generation mechanism of
hydroxyl radical species and its lifetime prediction during the
plasma-initiated ultraviolet (UV) photolysis. Sci. Rep. 5, 9332.
Baek, E., Joh, H., Kim, S., and Chung, T. (2016). Effects of the electri-
cal parameters and gas flow rate on the generation of reactive
species in liquids exposed to atmospheric pressure plasma
jets. Phys. Plasmas 23, 073515.
Baier, M., Foerster, J., Schnabel, U., Knorr, D., Ehlbeck, J., Herppich,
W.B., and Schloter, O. (2013). Direct non-thermal plasma treat-
ment for the sanitation of fresh corn salad leaves: evaluation of
physical and physiological effects and antimicrobial efficacy.
Postharvest Biol. Technol. 84, 81–87.
Barba-Espín, G., Hernández, J.A., and Diaz-Vivancos, P. (2012).
Role of H2O2 in pea seed germination. Plant Signal. Behav. 7,
193–195.
Barkai-Golan, R. (2001). Postharvest Diseases of Fruits and Vegeta-
bles: Development and Control (Amsterdam, The Netherlands:
Elsevier Science), pp. 25–32.
Bekeschus, S., Schmidt, A., Weltmann, K.-D., and von Woedtke, T.
(2016). The plasma jet kINPen – a powerful tool for wound heal-
ing. Clin. Plasma Med. 4, 19–28.
Beuchat, L.R., Clavero, M.R., and Jaquette, C.B. (1997). Effect of nisin
and temperature on survival, growth and enterotoxin produc-
tion characteristics of psychotropic B. cereus in beef gravy.
Appl. Environ. Microbiol. 63, 1953–1958.
Boehm, D., Curtin, J., Cullen, P.J., and Bourke, P. (2017). Hydrogen
peroxide and beyond-the potential of high-voltage plasma-
activated liquids against cancerous cells. Anti-Cancer Agents
Med. Chem. 17, DOI: 10.2174/1871520617666170801110517.
(Epub ahead of print).
Bowen, C.G., Greenwood, W., Guevara, P., and Washington, M.A.
(2015). Effectiveness of a dental unit waterline treatment
protocol with A-Dec ICX and Citrisil Disinfectants. Mil Med. 180,
1098–1104.
Braginsky, O., Vasilieva, A., Klopovskiy, K., Kovalev, A., Lopaev, D.,
Proshina, O., Rakhimova, T., and Rakhimov, A. (2005). Singlet
oxygen generation in O2 flow excited by RF discharge: I. Homo-
geneous discharge mode: α-mode. J. Phys. D Appl. Phys. 38,
3609.
Brandenburg, R. (2017). Dielectric barrier discharges: progress
on plasma sources and on the understanding of regimes and
single filaments. Plasma Sources Sci. Technol. 26, 053001.
Brisset, J. and Pawlat, J. (2016). Chemical effects of air plasma
species on aqueous solutes in direct and delayed exposure
modes: discharge, post-discharge and plasma activated water.
Plasma Chem. Plasma Process. 36, 355–381.
Bruggeman, P. and Leys, C. (2009). Non-thermal plasmas in
and in contact with liquids. J. Phys. D Appl. Phys. 42,
053001–053029.
Brune, B. (2003). Nitric oxide: NO apoptosis or turning it ON? Cell
Death Differ. 10, 864–869.
Burlica, R., Kirkpatrick, M.J., and Locke, B.R. (2006). Formation
ofreactive species in gliding arc discharges with liquid water.
J.Electrostat. 64, 35–43.
Chauvin, J., Judée, F., Yousfi, M., Vicendo, P., and Merbahi, N. (2017).
Analysis of reactive oxygen and nitrogen species generated
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
N.K. Kaushik etal.: Biological application of plasma stimulated liquids19
in three liquid media by low temperature helium plasma jet.
Sci.Rep. 7, 4562.
Chen, Z., Lin, L., Chenx X., Gjika E., and Keidar, M. (2016). Effects of
cold atmospheric plasma generated in deionized water in cell
cancer therapy. Plasma Process. Polym. 13, 1–6.
Chen, Z., Krasik, Y., Cousens, S., Ambujakshan, A., Corr, C., and
Dai, X. (2017). Generation of underwater discharges inside gas
bubbles using a 30-needles-to-plate electrode. J. Appl. Phys.
122, 153303.
Cheng, Y.U., Wu, C.H., Liu, C.T., Lin, C.Y., Chiang, H.P., Chen, T.W.,
Chen, C.Y., and Wu, J.S. (2017). Tooth bleaching by using a
helium-based low-temperature atmospheric pressure plasma
jet with saline solution. Plasma Process. Polym. 14, 1600235.
Dai, X., Corr, C., Ponraj, S., Maniruzzaman, M., Ambujakshan, A.,
Chen, Z., Kviz, L., Lovett, R., Rajmohan, G., Celis, D., etal.
(2015). Efficient and selectable production of reactive species
using a nanosecond pulsed discharge in gas bubbles in liquid.
Plasma Process. Polym. 13, 306–310.
Dobrynin, D., Fridman, G., Friedman, G., and Fridman, A. (2009).
Physical and biological mechanisms of plasma interaction with
living tissue. New J. Phys. 11, 1–26.
Duan, J., Lu, X., and He, J. (2017). The selective effect of plasma
activated medium in an in vitro co-culture of liver cancer and
normal cells. J. Appl. Phys. 121, 013302.
Dvorak, P., Mrkvickova, M., Obrusnik, A., Kratzer, J., Dedina, J., and
Prochazka, V. (2017). Fluorescence measurement of atomic
oxygen concentration in a dielectric barrier discharge. Plasma
Sources Sci. Technol. 26, 065020.
Ercan, U.K., Wang, H., Ji, H., Fridman, G., Brooks, A.D., and Joshi,
S.G. (2013). Nonequilibrium plasma-activated antimicrobial
solutions are broad-spectrum and retain their efficacies for
extended period of time. Plasma Process. Polym. 10, 544–555.
Fridman, A., Chirokov, A., and Gutsol, A. (2005). Non-thermal atmos-
pheric pressure discharges. J. Phys D Appl. Phys. 38, 1–24.
Fridman, G., Friedman, G., Gutsol, A., Shekhter, A.B., Vasilets, V.N.,
and Fridman, A. (2008). Applied plasma medicine. Plasma
Process. Polym. 5, 503–533.
Friedline, A., Zachariah, M., Middauch, A., Heiser, M., Khanna, N.,
Vaishampayan, P., and Rice, C. (2015). Sterilization of hydrogen
peroxide resistant bacterial spores with stabilized chlorine
dioxide. AMB Express. 5, 24.
Fthollah, S., Mirpour, S., Mansouri, P., Dehpour, A., Ghoranneviss,
M., Rahimi, N., Naraghi, Z., Chalangari, R., and Chalangari, K.
(2016). Investigation on the effects of the atmospheric pressure
plasma on wound healing in diabetic rats. Sci. Rep. 6, 19144.
Ghimire, B., Sornsakdanuphap, J., Hong, Y., Uhm, H., Weltmann, K.,
and Choi, E. (2017). The effect of the gap distance between an
atmospheric-pressure plasma jet nozzle and liquid surface on
OH and N2 species concentrations. Phys. Plasmas 24, 073502.
Girard, P., Arbabian, A., Fluery, M., Bauville, G., Puech, V., Dutreix,
M., and Sousa, J. (2016). Synergistic effect of H2O2 and NO2 in
cell death induced by cold atmospheric He plasma. Sci. Rep. 1,
29098.
Gorbanev, Y., O’Connell, D., and Chechik, V. (2016). Non-thermal
plasma in contact with water: the origin of species. Chemistry
22, 10.
Graves, D.B. (2012). The emerging role of reactive oxygen and nitro-
gen species in redox biology and some implications for plasma
applications to medicine and biology. J. Phys. D Appl. Phys. 45,
263001.
Guyader, P., Amgar, A., and Coignard, M. (1996) La désinfection.
In: Microbiologie Alimentaire Tome 1 ed. C.M. Bourgeois,
J.F. Mescle and J. Zucca, eds. (Paris: Tec et Doc Lavoisier),
pp.441–460.
Haertel, B., Woedtke, T., Weltmann, K., and Lindequist, U. (2014).
Non-thermal atmospheric-pressure plasma possible applica-
tion in wound healing. Biomol. Ther. 22, 477–490.
Harrison, F.E. (2012). A critical review of vitamin C for the prevention
of age-related cognitive decline and Alzheimer’s disease.
J. Alzheimers Dis. 29, 711–726.
Heinlin, J., Isbary, G., Stolz, W., Morfill, G., Landthaler, M.,
Shimizu, T., Steffes, B., Nosenko, T., Zimmermann, J., and
Karrer, S. (2011). Plasma applications in medicine with a spe-
cial focus on dermatology. J. Eur. Acad. Dermatol. Venereol.
25, 1–11.
Helmke, A., Hoffmeister, D., Berge, F., Emmert, S., Laspe, P.,
Mertens, N., Vioel, W., and Weltmann, K.D. (2011). Physical and
microbiological characterisation of Staphylococcus epidermidis
inactivation by dielectric barrier discharge plasma. Plasma
Process. Polym. 8, 278–286.
Hong, S.J., Dawson, T.M., and Dawson, V.L. (2004). Nuclear and
mitochondrial conversations in cell death: PARP-1 and AIF sign-
aling. Trends Pharmacol. Sci. 25, 259–264.
Horiba, M., Kamiya, T., Hara, H., and Adachi, T. (2017). Cytoprotec-
tive effects of mild plasma-activated medium against oxidative
stress in human skin fibroblasts. Sci. Rep. 7, e42208.
Horikoshi, S. and Serpone, N. (2017). In-liquid plasma: a novel tool
in the fabrication of nanomaterials and in the treatment of
wastewaters. RSC Adv. 7, 47196–47218.
Ikeda, J.I., Tanaka, H., Ishikawa, K., Sakakita, H., Ikehara, Y., and
Hori, M. (2018). Plasma-activated medium (PAM) kills human
cancer-initiating cells. Pathol. Int. 68, 23–30.
Ikehara, Y., Sakakita, H., Shimizu, N., Ikehara, S., and Nakanish, H.
(2013). Formation of membrane-like structures in clotted blood
by mild plasma treatment during hemostasis. J. Photopolym.
Sci. Technol. 26, 555–557.
Io, T., Uchida, G., Nakajima, A., Takenaka, K., and Setsuhara,
Y. (2016). Control of reactive oxygen and nitrogen species
production in liquid by nonthermal plasma jet with controlled
surrounding gas. Jpn. J. Appl. Phys. 56, 01AC06.
Iseki, S., Nakamura, K., Hayashi, M., Tanaka, H., Kondo, H.,
Kajiyama, H., Kano, H., Kikkawa, F., and Hori, M. (2012).
Selective killing of ovarian cancer cells through induction of
apoptosis by nonequilibrium atmospheric pressure plasma.
Appl. Phys. Lett. 100, 113702.
Ishida, C., Mori, M., Nakamura, K., Tanaka, H., Mizuno, M., Hori, M.,
Iwase, A., Kikkawa, F., and Toyokuni, S. (2016). Non-thermal
plasma prevents progression of endometriosis in mice. Free
Rad. Res. 50, 1131–1139.
Ismael, S.Z., Khandaker, M.M., Mat, N., and Boyce, A.N. (2015).
Effects of hydrogen peroxide on growth, development and
quality of fruits: a review. J. Agron. 14, 331–336.
Jablonowski, H. and Woedtke, T.V. (2015). Research on plasma
medicine-relevant plasma liquid interaction: what happened in
the past five years? Clin. Plasma Med. 3, 42–52.
Janda, M., Sovits, V.M., Hensel, K., and Machala, Z. (2016). Genera-
tion of antimicrobial NOx by atmospheric air transient spark
discharge. Plasma Chem. Plasma Process. 36, 767–781.
Jha, N., Ryu, J.J., Choi, E.H., and Kaushik, N.K. (2017). Generation
and role of reactive oxygen and nitrogen species induced by
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
20 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
plasma, lasers, chemical agents, and other systems in den-
tistry. Oxid. Med. Cell Longev. 2017, 7542540.
Joshi, S.G., Cooper, M., Yost, A., Paff, M., Ercan, U.K., Fridman, G.,
Friedman, G., Fridman, A., and Brooks, A.D. (2011). Nonther-
mal dielectric-barrier discharge plasma-induced inactivation
involves oxidative DNA damage and membrane lipid peroxida-
tion in Escherichia coli. Antimicrob. Agents Chemother. 55,
1053–1062.
Joslin, J., McCall, J.R., Bzdek, J., Johnson, D., and Hybertson, B.
(2016). Aqueous plasma pharmacy: preparation methods,
chemistry, and therapeutic applications. Plasma Med. 6,
135–177.
Judée, F., Fongia, C., Ducommun, F., Yousfi, M., Lobjois, V., and
Merbahi, N. (2016). Short and long time effects of low tem-
perature plasma activated media on 3D multicellular tumor
spheroids. Sci. Rep. 6, 21421.
Judée, F., Simon, S., and Dufour, T. (2018). Plasma-activation of tap
water using DBD for agronomy applications: identification and
quantification of long lifetime chemical species and produc-
tion/consumption mechanisms. Water Res. 133, 47–59.
Kalghatgi, S., Friedman, G., Fridman, A., and Clyne, A.M. (2010).
Endothelial cell proliferation is enhanced by low dose non-
thermal plasma through fibroblast growth factor-2 release.
Ann. Biomed. Eng. 38, 748–757.
Kamgang-Youbi, G., Herry, J.M., Bellon-Fontaine, M.N., Brisset,J.L.,
Doubla, A., and Naïtali, M. (2007). Evidence of temporal
postdischarge decontamination of bacteria by gliding electric
discharges: application to Hafnia alvei. Appl. Environ.
Microbiol. 73, 4791–4796.
Kamgang-Youbi, G., Herry, J.M., Brisset, J.L., Bellon-Fontaine, M.N.,
Doubla, A., and Naïtali, M. (2008). Impact on disinfection effi-
ciency of cell load and of planktonic/adherent/detached state:
case of Hafnia alvei inactivation by plasma activated water.
Appl. Microbiol. Biotechnol. 81, 449–457.
Kamgang-Youbi, G., Herry, J.M., Brisset, J.L., Bellon-Fontaine, M.N.,
Doubla, A., and Naıtali, M. (2009). Microbial inactivation using
plasma-activated water obtained by gliding electric discharges.
Lett. Appl. Microbiol. 48, 13–18.
Kang, Z.Q. (2016). The bleaching efficiency and bio-safety assess-
ment of plasma activated water by low conc. H2O2. Global
Thesis. 2016.
Kaushik, N.K., Kaushik, N., Yoo, K.C., Uddin, N., Kim, J.S., Lee, S.-J.,
and Choi, E.H. (2016). Low doses of PEG-coated gold nano-
particles sensitize solid tumors to cold plasma by blocking the
PI3K/AKT-driven signaling axis to suppress cellular transforma-
tion by inhibiting growth and EMT. Biomaterials 87, 118–130.
Kawasaki, T., Kusumegi, S., Kudo, A., Sakanoshita, T., Tsurumaru, T.,
and Sato, A. (2016). Effects of gas flow rate on supply of reac-
tive oxygen species into a target through liquid layer in cold
plasma jet. IEEE Trans. Plasma Sci. 44, 3223.
Kayes, M.M., Critzer, F.J., Kelly-Wintenberg, K., Roth, J.R., Montie,
T.C., and Golden, D.A. (2007). Inactivation of foodborne patho-
gens using a one atmosphere uniform glow discharge plasma.
Foodborne Pathog. Dis. 4, 50–59.
Keidar, M., Shashurin, A., Volotskova, O., Stepp, M., Srinivasan, P.,
Sandler, A., and Trink, B. (2013). Cold atmospheric plasma in
cancer therapy. Phys. Plasmas 20, 057101.
Kim, P.K., Zamora, R., Petrosko, P., and Billiar, T.R. (2001). The
regulatory role of nitric oxide in apoptosis. Int. J. Immunophar-
macol. 1, 1421–1441.
Kim, S.J., Chung, T.H., Bae, S.H., and Leem, S.H. (2009). Bacteria
inactivation using atmospheric pressure single pin electrode
microplasma jet with a group ring. Appl. Phys. Lett. 94, 141502.
Kim, Y., Hong, Y., Baik, K., Kwon, G., Choi, J. Cho, G, Uhm, H., Kim,
D., and Choi, E. (2014). Measurement of reactive hydroxyl
radical species inside the biosolutions during non-thermal
atmospheric pressure plasma jet bombardment onto the
solution. Plasma Chem. Plasma Process. 34, 457.
Kim, Y., Jin, S., Han, G., Kwon, G., Choi, J., Choi, E., Uhm, S.,
andCho, G. (2015). Plasma apparatuses for biomedical
applications. IEEE Trans. Plasma Sci. 43, 944.
King, D.A., Sheafor, M.W., and Hurst, J.K. (2006). Comparative toxici-
ties of putative phagocyte-generated oxidizing radicals toward
a bacterium (Escherichia coli) and a yeast (Saccharomyces
cerevisiae). Free Radic. Biol. Med. 41, 765–774.
Knake, N., Reuter, S., Niemi, K., Schulz, V., and Winter, J. (2008).
Absolute atomic oxygen density distributions in the effluent of
a microscale atmospheric pressure plasma jet. J. Phys. D Appl.
Phys. 41, 194006.
Koban, I., Holtfreter, B., Hübner, N.O., Matthes, R., Sietmann, R.,
Kindel, E., Weltmann, K.D., Welk, A., Kramer, A., and Kocher, T.
(2011). Antimicrobial efficacy of non-thermal plasma in compar-
ison to chlorhexidine against dental biofilms on titanium discs
in vitro – proof of principle experiment. J. Clin. Periodontol. 38,
956–965.
Kolb, J.F., Mohamed, A.A.H., Price, R.O., Swanson, R.J., Bowman, A.,
Chiavarini, R.L., and Schoenbach, K.H. (2008). Cold atmos-
pheric pressure air plasma jet for medical applications. Appl.
Phys. Lett. 92, 241501.
Kostov, K., Machida, M., Prysiazhnyi, V., and Honda, R. (2015).
Transfer of a cold atmospheric pressure plasma jet through
a long flexible plastic tube. Plasma Sources Sci. Technol. 24,
025038.
Kumar, N., Park, J.H., Jeon, S.N., Park, B.S., Choi, E.H., and Attri, P.
(2016). The action of microsecond-pulsed plasma-activated
media on the inactivation of human lung cancer cells. J. Phys.
D 49, 115401.
Kuninova, S., Zaviskova, K., Uherkova, L., Zablotskii, V., Churpita,
O., Lunov, O., and Dejneka, A. (2017). Non-thermal air plasma
promotes the healing of acute skin wounds in rats. Sci. Rep. 7,
45183.
Kuok, S.N. (2017). Theory of low-temperature physics. In: Springer
Series on Atomic, Optical and Plasma Physics, Vol.95.
ISBN:978-3-319-43719-4. DOI: 10.1007/978-3-319-43721-7.
Kurake, N., Tanaka, H., Ishikawa, K., Kondo, T., Sekine, M.,
Nakamura, K., Kajiyama, H., Kikkawa, F., Mizuno, M., and
Hori, M. (2016). Cell survival of glioblastoma grown in medium
containing hydrogen peroxide and/or nitrite, or in plasma-
activated medium. Arch. Biochem. Biophys. 605, 102–108.
Kurake, N., Tanaka, H., Ishikawa, K., Takeda, K., Hashizume, H.,
Nakamura, K., Kajiyama, H, Kondo, T., Kikkawa, F., Mizuno,
M., etal. (2017). Effects of ˙OH and ˙NO radicals in the aque-
ous phase on H2O2 and NO2
generated in plasma-activated
medium. J. Phys. D Appl. Phys. 50, 155202.
Kurita, M., Shimizu, M., Sano, K., Nakajima, T., Yasuda, H.,
Takashima, K., and Mizuno, A. (2014). Radical reaction in
aqueous media injected by atmospheric pressure plasma jet
and protective effect of antioxidant reagents evaluated by
single-molecule DNA measurement. Jap. J. Appl. Phys. 53,
05FR01.
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
N.K. Kaushik etal.: Biological application of plasma stimulated liquids21
Laroussi, M. (2002). Nonthermal decontamination of biological
media by atmospheric-pressure plasmas: review, analysis, and
prospects. IEEE Trans. Plasma Sci. 30, 1409–1455.
Laroussi, M. (2005). Low temperature plasma-based sterilization:
overview and state-of-the-art. Plasma Process. Polym. 2,
391400.
Laroussi, M. and Leipold, F. (2004). Evaluation of the roles of reac-
tive species, heat, and UV radiation in the inactivation of bacte-
rial cells by air plasmas at atmospheric pressure. Int. J. Mass
Spectrom. 233, 81–86.
Laroussi, M., Mendis, D.A., and Rosenberg, M. (2003). Plasma inter-
action with microbes. New J. Phys. 5, 41.1–41.10.
Laroussi, M., Lu, X., and Keidar, M. (2017). Perspective: the physics,
diagnostics, and applications of atmospheric pressure low
temperature plasma sources used in plasma medicine. J. Appl.
Phys. 122, 020901. DOI: 10.1063/1.4993710.
Laurita, R., Barbieri, D., Gherardi, M., Colombo, V., and Lukes, P.
(2015). Chemical analysis of reactive species and antimicrobial
activity of water treated by nanosecond pulsed DBD air plasma.
Clin. Plasma Med. 3, 53–61.
Levko, D., Sharma, A., and Raja, L. (2016). Plasmas generated in
bubbles immersed in liquids: direct current streamers versus
microwave plasma. J. Phys. D Appl. Phys. 49, 285205.
Li, Y., Kang, M.H., Uhm, H.S., Lee, G.J., Choi, E.H., and Han, I.
(2017a). Effects of atmospheric-pressure non-thermal bio-
compatible plasma and plasma activated nitric oxide water on
cervical cancer cells. Sci. Rep. 7, 45781.
Li, Y., Pan, J., Ye, G., Zhang, Q., Wang, J., Zhang, J., and Fang, J.
(2017b). In vitro studies of the antimicrobial effect of non-ther-
mal plasma-activated water as a novel mouthwash. Eur. J. Oral
Sci. 125, 463–470.
Liebermann, D.A., Hoffman, B., and Steinman, R.A. (1995). Molecu-
lar controls of growth arrest and apoptosis: p53-dependent and
independent pathways. Oncogene 11, 199–210.
Lin, A., Truong, B., Patel, S., Kaushik, N., Choi, E.H., Fridman, G.,
Fridman, A., and Miller, V. (2017). Nanosecond-pulsed DBD
plasma-generated reactive oxygen species trigger immuno-
genic cell death in A549 lung carcinoma cells through intracel-
lular oxidative stress. Int. J. Mol. Sci. 18, 966.
Linley, E., Denyer, S., McDonnell, G., Simons, C., and Maillard, J.
(2012). Use of hydrogen peroxide as a biocide: new consid-
eration of its mechanisms of biocidal action. J. Antimicrob.
Chemother. 67, 1589–1596.
Liu, D.X., Liu, Z.C., Chen, C. Yang, A.J., Li,D., Rong, M.Z., Chen, H.L.,
and Kong, M.G. (2016). Aqueous reactive species induced by a
surface air discharge: heterogeneous mass transfer and liquid
chemistry pathways. Sci. Rep. 6, 23737.
Lotfy, K. (2016). Cold atmospheric plasma and oxidative stress: reac-
tive oxygen species vs. antioxidant. Austin Biochem. 1, 1001.
Lu, X., Jiang, Z., Xiong, Q., Tang, Z., and Pan, Y. (2008). A single
electrode room-temperature plasma jet device for biomedical
applications. Appl. Phys. Lett. 92, 151504.
Lu, T., Qiao, Y., and Liu, X. (2012a). Surface modification of biomate-
rials using plasma immersion ion implantation and deposition.
Interface Focus 2, 325–336.
Lu, X., Laroussi, M., and Puech, V. (2012b). On atmospheric-pressure
non-equilibrium plasma jets and plasma bullets. Plasma
Sources Sci. Technol. 21, 034005.
Lu, X., Naidis, G.V., Laroussi, M., Reuter, S., Graves, D.B., and
Ostrikov, K. (2016). Reactive species in non-equilibrium
atmospheric-pressure plasmas: generation, transport, and
biological effects. Phys. Rep. 630, 1–84.
Lukes, P., Brisset, J.L., and Locke, B.R. (2012). Biological effects
of electrical discharge plasma in water and in gas-liquid
environments. In: Plasma Chemistry and Catalysis in
Gases and Liquids, pp. 309–352. ISBN: 9783527330065.
DOI:10.1002/9783527649525.ch8.
Lukes, P., Dolezalova, E., Sisrova, I., and Clupek, M. (2014).
Aqueous-phase chemistry and bactericidal effects from an
air discharge plasma in contact with water: evidence for the
formation of peroxynitrite through a pseudo-second-order
post-discharge reaction of H2O2 and HNO2. Plasma Sources Sci.
Technol. 23, 015019.
Ma, R., Feng, H., Li, F., Liang, Y., Zhang, Q., Zhu, W., Zhang, J.,
Becker, K.H., and Fang, J. (2012). An evaluation of anti-oxi-
dative protection for cells against atmospheric pressure cold
plasma treatment. Appl. Phys. Lett. 100, 12370.
Ma, R., Wang, G., Tian, Y., Wang, K., Zhang, J., and Fang, J. (2015).
Non thermal plasma activated water inactivation of food borne
pathogen on fresh produce. J. Hazard. Mat. 300, 643–651.
Ma, R., Yu, S., Tian, Y., Wang, K., Sun, C., Li, X., Zhang, J., Chen, K.,
and Fang, J. (2016). Effect of non-thermal plasma-activated
water on fruit decay and quality in postharvest Chinese bayber-
ries. Food Bioprod. Technol. 9, 1825–1834.
Maheux, S., Duday, D., Belmonte, T., Penny, C., Cauchie, H.M.,
Clément, F., and Choquet, P. (2015). Formation of ammonium in
saline solution treated by nanosecond pulsed cold atmospheric
microplasma: a route to fast inactivation of E. coli bacteria. RSC
Adv. 5, 42135–42140.
Mancinelli, R. and Mckay, C. (1983). Effects of nitric oxide and
nitrogen dioxide on bacterial growth. Appl. Environ. Microbiol.
46, 198–202.
Mann, M.S., Tiede, R., Gavenis, K., Daeschlein, G., Bussiahn, R.,
Weltmann, K.-D., Emmert, S., Woedtke, T.V., and Ahmed, R.
(2016). Introduction to DIN-specification 91315 based on the
characterization of the plasma jet kINPen® MED. Clin. Plasma Med.
4, 35–45.
Marder, E.P., Griffin, P.M., Cieslak, P.R., Dunn, J., Hurd, S., Jervis, R.,
Lathrop, S., Muse, A., Ryan P., Smith, K., etal. (2018). Preliminary
incidence and trends of infections with pathogens transmitted
commonly through food – foodborne diseases active surveillance
network, 10 U.S. Sites, 2006–2017. Weekly 67, 324–328.
Matsumoto, R., Shimizu, K., Nagashima, T., Tanaka, H., Mizuno, M.,
Kikkawa, F., Hori, M., and Honda, H. (2016). Plasma-activated
medium selectively eliminates undifferentiated. Regen. Ther.
5, 55–63.
Miyamoto, K., Ikehara, S., Takei, H., Akimoto, Y., Sakakita, H.,
Ishikawa, K., Ueda, M., Ikeda, J., Yamagishi, M., and Kim, J.
(2016). Red blood cell coagulation induced by low-temperature
plasma treatment. Arch. Biochem. Biophys. 605, 95–101.
Mohades, S., Laroussi, M., Sears, J., Barekzi, N., and Razavi, H.
(2015). Evaluation of the effects of a plasma activated medium
on cancer cells. Phys. Plasmas 22, 122001.
Mohades, S., Barekzi, N., Razavi, H., Maruthamuthu, V., and
Laroussi, M. (2016a). Intraperitoneal administration of
plasma-activated medium: proposal of a novel treatment
option for peritoneal metastasis from gastric cancer. Plasma
Process. Polym. 13, 12.
Mohades, S., Barekzi, N., Razavi, H., Maruthamuthu, V., and
Laroussi, M. (2016b). Temporal evaluation of the anti-tumor
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
22 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
efficiency of plasma-activated media. Plasma Process. Polym.
13, 1206.
Mohades, S., Laroussi, M., and Maruthamuthu, V. (2017). Moderate
plasma activated media suppresses proliferation and migration
of MDCK epithelial cells. J. Phys. D Appl. Phys. 50, 185205.
Moreau, M., Orange, N., and Feuilloley, M.G. (2008). Non-thermal
plasma technologies: new tools for bio-decontamination.
Biotechnol. Adv. 26, 610–617.
Morris, A.D., McCombs, G.B., Akan, T., Hynes, W., Laroussi, M., and
Tolle, S.L. (2009). Cold plasma technology: bactericidal effects
on Geobacillus stearothermophilus and Bacillus cereus micro-
organisms. J. Dent. Hyg. 83, 55–61.
Nagatsu, M., Terashita, F., Nonaka, H., Xu, L., Nagata, T., and Koide,
Y. (2005). Effects of oxygen radicals in low-pressure surface
wave plasma on sterilization. Appl. Phys. Lett. 86, 211502.
Naim, A.H. (2015). Influence of pre-sowing treatment with hydrogen
peroxide on alleviation salinity stress impacts on cow pea
germination and early seedling development. Asian J. Plant Sci.
5, 62–67.
Naïtali, M., Kamgang-Youbi, G., Herry, J.M., Bellon-Fontaine,
M.-N., and Brisset, J.L. (2010). Combined effects of long-living
chemical species during microbial inactivation using atmos-
pheric plasma-treated water. Appl. Environ. Microbiol. 76,
7662–7664.
Nakamura, K., Peng, Y., Utsumi, F., Tanaka, H., Mizuno, M., Toyokuni,
M., Hori, M., Kikkawa, F., and Kajiyama, H. (2017). Novel
intraperitoneal treatment with non-thermal plasma-activated
medium inhibits metastatic potential of ovarian cancer cells.
Sci. Rep. 7, 6085.
Narayanasamy, P. (2005). Postharvest Pathogens and Disease Man-
agement (Hoboken, USA: John Wiley & Sons Inc.).
Nikirov, A., Xiong, Q., Britun, N., Snyders, R., Lu, X., and Leys, C.
(2011). Absolute concentration of OH radicals in atmospheric
pressure glow discharges with a liquid electrode measured by
laser-induced fluorescence spectroscopy. Appl. Phys. Express
4, 026102.
Ninomiya, K., Ishijima, T., Imamura, M., Yamahara, T., Enomoto, H.,
Takahashi, K., Tanaka Y., Uesugi, Y., and Shimizu, N. (2013).
Evaluation of extra- and intracellular OH radical generation,
cancer cell injury, and apoptosis induced by a non-thermal
atmospheric-pressure plasma jet. J. Phys. D 46, 425401.
Nofel, M., Chauvin, J., Vicendo, P., and Judée, F. (2017). Effects of
plasma activated medium on head and neck FaDu cancerous
cells: comparison of 3D and 2D response. Anti-Cancer Agents
Med. Chem. 17, DOI: 10.2174/1871520617666170801111055.
Norberg, S., Tian, W., Johnsen, E., and Kushner, M. (2014). Atmos-
pheric pressure plasma jets interacting with liquid covered
tissue: touching and not-touching the liquid. J. Phy. D: Appl.
Phys. 47, 475203.
Oehmigen, K., Hahnel, M., Brandenburg, R., Wilke, C., Weltmann,
K.D., and Von-Woedtke, T. (2010). The role of acidification
for antimicrobial activity of atmospheric pressure plasma in
liquids. Plasma Process. Polym. 7, 250–257.
Oehmigen, K., Winter, J., Hahnel, M., Wilke, C., Brandenburg, R.,
Weltmann, K.D., and Von-Woedtke, T. (2011). Estimation of
possible mechanisms of Escherichia coli inactivation by plasma
treated sodium chloride solution. Plasma Process. Polym. 8,
904–913.
Oh, J., Szili, E., Ogawa, K., Short, R., Ito, M., Furuta, M., and Hatta, A.
(2018). UV–vis spectroscopy study of plasma-activated water:
dependence of the chemical composition on plasma exposure
time and treatment distance. Jpn. J. Appl. Phys. 57, 0102B9.
Ouf, S.A., Mohamed, A.A.H., and El-Sayed, W.S. (2016). Fungal
decontamination of fleshy fruit water washes by double atmos-
pheric pressure cold plasma. Clean 44, 134–142.
Pan, J., Sun, K., Liang, Y.D., Sun, P., Yang, X.H., Wang, J., and Becker,
K.H. (2013). Cold plasma therapy of a tooth root canal infected
with Enterococcus faecalis biofilms in vitro. J. Endod. 39,
105–110.
Pan, J., Li, Y.L., Liu, C.M., Tian, Y., Yu, S., Wang, K.L., Zhang, J., and
Fang, J. (2017). Investigation of cold atmospheric plasma-
activated water for the dental unit waterline system contamina-
tion and safety evaluation in vitro. Plasma Chem. Plasma P. 37,
1091–1103.
Pankaj, S.K., Bueno-Ferrer, C., Misra, N.N., Milosavljevic, V.,
O’Donnell, C.P., Bourke, P., and Cullen, P.J. (2014). Applications
of cold plasma technology in food packaging. Trends Food Sci.
Technol. 35, 5–17.
Park, G.Y., Park, S.J., Choi, M.Y., Koo, I.G., Byun, J.H., Hong, J.W.,
Sim, J.Y., Collins, G.J., and Lee, J.K. (2012). Atmospheric-
pressure plasma sources for biomedical applications. Plasma
Sources Sci. Technol. 21, 043001.
Patel, R. (2005). Biofilms and antimicrobial resistance. Clin. Orthop.
Relat. Res. 437, 41–47.
Pei, X., Lu, Y., Wu, S., Xiong, Q., and Lu, X. (2013). A study on the
temporally and spatially resolved OH radical distribution of a
room-temperature atmospheric-pressure plasma jet by laser-
induced fluorescence imaging. Plasma Sources Sci. Tech. 22,
025023.
Peterson, P.E. (2003). World health report. Community Dent. Oral
Epidemiol. 31, 3–24.
Raja Danasekaran, G.M. and Annadurai, K. (2014). Prevention of
healthcare-associated infections: protecting patients, saving
lives. Int. J. Community Med. Public Health 1, 67–68.
Rehman, M.U., Jawaid, P., Uchiyama, H., and Kondo, T. (2016). Com-
parison of free radicals formation induced by cold atmospheric
plasma, ultrasound, and ionizing radiation. Arch. Biochem.
Biophys. 605, 19–25.
Reuter, S., Niemi, K., Gathen, V., and Dobele, H. (2009). Generation
of atomic oxygen in the effluent of an atmospheric pressure
plasma jet. Plasma Sources Sci. Technol. 18, 015006.
Rumbach, P., Bartels, D.M., Sankaran, R.M., and Go, D.B. (2015). The
solvation of electrons by an atmospheric-pressure plasma. Nat.
Commun. 6, 7248.
Santos, D.M.F., Sequeira, C.A.C., and Figueiredo, J.L. (2013). Hydro-
gen production by alkaline water electrolysis. Quim. Nova. 36,
1176–1193.
Sato, Y., Yamada, S., Takeda, S., Hattori, N., Nakamura, K.,
Tanaka, H., Mizuno, M., Hori, M., and Kodera, Y. (2018). Effect
of plasma-activated lactated ringer’s solution on pancre-
atic cancer cells in vitro and in vivo. Ann. Surg. Oncol. 25,
299–307.
Savary, S., Ficke, A., Aubertot, J.N., and Hollier, C. (2012). Crop
losses due to diseases and their implications for global food
production losses and food security. Food Sec. 4, 519–537.
Shang, K., Li, J., Wang, X., Yao, D., Lu, N., Jiang, N., and Wu, Y.
(2016). Evaluating the generation efficiency of hydrogen
peroxide in water by pulsed discharge over water surface
andunderwater bubbling pulsed discharge. Jpn. J. Appl.
Phys. 55, 01AB02.
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
N.K. Kaushik etal.: Biological application of plasma stimulated liquids23
Shashurin, A., Keidar, M., Bronnikov, S., Jurjus, R., and Stepp, M.
(2008). Living tissue under treatment of cold plasma atmos-
pheric jet. Appl. Phys. Lett. 93, 181501.
Shen, J., Tian, Y., Li, Y., Ma, R., Zhang, Q., Zhang, J., and Fang, J.
(2016). Bactericidal effects against S. aureus and physicochem-
ical properties of plasma activated water stored at different
temperatures. Sci. Rep. 6, 28505.
Shi, L., Yu, L., Zou, F., Hu, H., Liu, K., and Lin, Z. (2017). Gene
expression profiling and functional analysis reveals that p53
pathway-related gene expression is highly activated in cancer
cells treated by cold atmospheric plasma-activated medium.
Peer J. 5, e3751.
Siddique, S.S., Hardy, G.E. St. J., and Bayliss, K.L. (2018). Cold
plasma: a potential new method to manage postharvest dis-
eases caused by fungal plant pathogens. Plant Pathol. 10, 1–39.
Sivachandiran, L. and Khacef, A. (2017). Enhanced seed germination
and plant growth by atmospheric pressure cold air plasma:
combined effect of seed and water treatment. RSC Adv. 7,
1822–1832.
Srivastava, N. and Wang, C. (2011). Effects of water addition on OH
radical generation and plasma properties in an atmospheric
argon microwave plasma jet. J. App. Phys. 110, 053304.
Stewart, P.S. and Costerton, J.W. (2001) Antibiotic resistance of
bacteria in biofilms. Lancet 358, 135–138.
Su, X., Tian, Y., Zhou, H., Li, Y., Zhang, Z., Jiang, B., Yang, B., Zhang,
J., and Fang, J. (2018). Inactivation efficacy of non-thermal
plasma activated solutions against Newcastle disease virus.
Appl. Environ. Microbiol. 84, e02836-17.
Sun, P., Wu, H., Bai, N., Zhou, H., Wang, R., Feng, H., Zhu, W., Zhang,
J., and Fang, J. (2012). Inactivation of Bacillus subtilis spores in
water by a direct-current, cold atmospheric-pressure air plasma
microjet. Plasma Process. Polym. 9, 157–164.
Takaki, K., Takahata, J., Watanabe, S., Satta, N., Yamada, O.,
Fujio,T., and Sasaki, Y. (2013). Improvements in plant growth
rate using underwater discharge. J. Phys. Conf. Ser. 418,
012140.
Takeda, S., Yamada, S., Hattori, N., Nakamura, K., Tanaka, H.,
Kajiyama, H., Kanda, M., Kobayashi, D., Tanaka, C., Fujii,
T, etal. (2017). Intraperitoneal administration of plasma-
activatedmedium: proposal of a novel treatment option for
peritoneal metastasis from gastric cancer. Ann. Surg. Oncol.
24, 1188–1194.
Tanaka, H. (2012). Cell survival and proliferation signaling pathways
are downregulated by plasma-activated medium in glioblas-
toma brain tumor cells. Plasma Med. 2, 207–220.
Tanaka, H., Mizuno, M., Ishikawa, K., Takeda, K., Nakamura, K.,
Utsumi, F., Kajiyama, H., Kano, H., Okazaki, Y., Toyokuni, S.,
etal. (2014). Plasma medical science for cancer therapy:
towards cancer therapy using nonthermal atmospheric plasma.
IEEE Trans. Plasma Sci. 42, 3760.
Tanaka, H., Mizuno, M., Toyokuni, S., Maruyama, S., Kodera, Y.,
Terasaki, H., Adachi, T., Kato, M., Kikkawa, F., and Hori, M.
(2015a). Cancer therapy using non-thermal atmospheric pres-
sure plasma with ultra-high electron density. Phys. Plasmas 22,
122003.
Tanaka, H., Mizuno, M., Ishikawa, K., Kondo, H., Takeda, K.,
Hashizume, H., Nakamura, K., Utsumi, F., Kajiyama, H., Kano,
H., etal. (2015b). Plasma with high electron density and
plasma-activated medium for cancer treatment. Clin. Plasma
Med. 3, 71–76.
Tanaka, H., Nakamura, K., Mizuno, M., Ishikawa, K., Takeda, K.,
Kajiyama, H., Utsumi, F., Kikkawa, F., and Hori, M. (2016).
Non-thermal atmospheric pressure plasma activates lactate in
Ringer’s solution for anti-tumor effects. Sci. Rep. 6, 36282.
Thirumdas, R. (2018). Exploitation of cold plasma technology for
enhancement of seed germination. Agri. Res. Tech. 13, 1–4.
Thiyagarajan, M., Sarani, A., and Nicula, C. (2013). Optical emission
spectroscopic diagnostics of a non-thermal atmospheric pres-
sure helium-oxygen plasma jet for biomedical applications.
J.Appl. Phys. 113, 233302.
Toyokuni, S. (2016). The origin and future of oxidative stress pathol-
ogy: from the recognition of carcinogenesis as an iron addic-
tion with ferroptosis-resistance to non-thermal plasma therapy.
Pathol. Int. 66, 245–259.
Traylor, M.J., Pavlovich, M.J., Karim, S., Hait, P., Sakiyama, Y.,
Clark, D.S., and Graves, D.B. (2011). Long-term antibacterial
efficacy of air plasma-activated water. J. Phys. D Appl. Phys. 44,
472001.
Tredwin, C., Naik, S., Lewis, N., and Scully, C. (2006). Hydrogen per-
oxide tooth-whitening (bleaching) products: review of adverse
effects and safety issues. Br. Dent. J. 200, 371–376.
Tresp, H., Hammer, M., Winter, J., Weltmann, K., and Reuter, S.
(2013). Quantitative detection of plasma-generated radicals
inliquids by electron paramagnetic resonance spectroscopy.
J.Phys. D Appl. Phys. 46, 435401.
Tripathi, P. and Dubey, N. (2004). Exploitation of natural products
as an alternative strategy to control postharvest fungal rot-
ting of fruit and vegetables. Postharvest Biol. Technol. 32,
235–245.
Troyano, A., Sancho, P., Fernandez, C., Blas, E., Bernardi, P., and
Aller, P. (2003). The selection between apoptosis and necrosis
is differentially regulated in hydrogen peroxide-treated and
glutathione-depleted human promonocytic cells. Cell Death
Differ. 10, 889–898.
Tsutsui, C., Lee, M., Takahashi, G., Murata, S., Hirata, T., Kanai, T.,
and Mori, A. (2014). Treatment of cardiac disease by inhala-
tion of atmospheric pressure plasma. Jpn. J. Appl. Phys. 53,
060309.
Uchida, G., Nakajima, A., Ito, T., Takenaka, K., Kawasaki, T., Koga,
K., Shiratani, M., and Setsuhara, Y. (2016). Effects of nonther-
mal plasma jet irradiation on the selective production of H2O2
and NO2
in liquid water. J. Appl. Phys. 120, 203302.
Uchida, G., Takenaka, K., Takeda, K., Ishikawa, K., Hori, M., and
Setsuhara, Y. (2017). Selective production of reactive oxygen
and nitrogen species in the plasma-treated water by using a
nonthermal high-frequency plasma jet. Jpn. J. Appl. Phys. 57,
0102B4.
Ueda, M., Yamagami, D., Watanabe, K., Mori, A., Kimura, H., Sano,
K., Saji, H., Ishikawa, K., Mori, M., Sakakita, H., etal. (2015).
Histological and nuclear medical comparison of inflammation
after hemostasis with non-thermal plasma and thermal coagu-
lation. Plasma Process. Polym. 12, 1338–1342.
Uhm, H. (2015). Generation of various radicals in nitrogen plasma
and their behavior in media. Phys. Plasmas 22, 123506.
United Nations, Department of Economic and Social Affairs, Popula-
tion Division. (2015). World Population Prospects: The 2015
Revision, Key Findings and Advance Tables. Working Paper No.
ESA/P/WP.241.
Utsumi, F., Kajiyama, H., Nakamura, K., Tanaka, H., Mizuno, M.,
Ishikawa, K., Kondo, H., Kano, H., Hori, M., and Kikkawa, F.
Bereitgestellt von | De Gruyter / TCS
Angemeldet
Heruntergeladen am | 15.10.18 14:41
24 N.K. Kaushik etal.: Biological application of plasma stimulated liquids
(2013). Effect of indirect non-equilibrium atmospheric pressure
plasma on anti-proliferative activity against chronic chemo-
resistant ovarian cancer cells in vitro and in vivo. PLoS One 8,
e81576.
Van-Gils, C.A.J., Hofmann, S., Boekema, B.K.H.L., Brandenburg, R.,
and Bruggeman, P.J. (2013). Mechanisms of bacterial inactiva-
tion in the liquid phase induced by a remote RF cold atmos-
pheric pressure plasma jet. J. Phys. D Appl. Phys. 46, 1–14.
Verlackt, C., Boxem, W., and Bogaerts, A. (2018). Transport and
accumulation of plasma generated species in aqueous solu-
tion. Phys. Chem. Chem. Phys. 20, 6845–6859.
Vlad, I.E. and Anghel, S.D. (2017). Time stability of water activated
by different on-liquid atmospheric pressure plasmas.
J. Electrostat. 87, 284–292.
Vyhnankova, E., Kozakova, Z., Krcma, F., and Hrdlicka, A. (2014).
Influence of electrode material on hydrogen peroxide genera-
tion by DC pinhole discharge. Open Chem. 13, 218–223.
Wang, M., Holmes, B., Cheng, X., Zhu, W., Keidar, M., and Zhang,
L.G. (2013). Cold atmospheric plasma for selectively ablating
metastatic breast cancer cells. PLoS One 8, e73741.
Weller, R., Price, R.J., Ormerod, A.D., Benjamin, N., and Leifert, C.
(2001). Microbial effect of acidified nitrite on dermatophyte
fungi, Candida and bacterial skin pathogens. J. Appl. Microbiol.
90, 648–652.
Weltmann, K.-D. and von Woedtke, T. (2017). Plasma medicine – cur-
rent state of research and medical application. Plasma Phys.
Control. Fusion 59, 014031.
Winter, J., Brandenburg, R., and Weltmann, K. (2015). Atmospheric
pressure plasma jets: an overview of devices and new direc-
tions. Plasma Sources Sci. Technol. 24, 064001.
Xiang, J., Wan, C., Guo, R., and Guo, D. (2016). Is hydrogen peroxide
a suitable apoptosis inducer for all cell types? BioMed. Res. Int.
2016, 7343965.
Xiong, Q., Yang, Z., and Bruggeman, P. (2015). Absolute OH density
measurements in an atmospheric pressure dc glow discharge
in air with water electrode by broadband UV absorption
spectroscopy. J. Phys. D Appl. Phys. 48, 424008.
Xu, Y., Tian, Y., Mab, R., Liu, Q., and Zhang, J. (2016). Effect of plasma
activated water on the postharvest quality of button mush-
rooms, Agaricus bisporus. Food Chem. 197, 436–444.
Yan, D.Y., Sherman, J.H., Cheng X.Q., Ratovitski, E., Canady, J., and
Keidar, M. (2014). Controlling plasma stimulated media in can-
cer treatment application. Appl. Phys. Lett. 105, 224101.
Yan, D., Talbot, A., Nourmohammadi, N., Sherman, J.H., Cheng, X.,
and Keidar, M. (2015). Toward understanding the selective anti-
cancer capacity of cold atmospheric plasma – a model based
on aquaporins. Biointerphases 10, 040801.
Yan, D., Cui, H., Zhu, W., Nourmohammadi, N., Milberg, J., Zhang,
L.G., Sherman, J.H., and Keidar, M. (2017). The specific vulner-
abilities of cancer cells to the cold atmospheric plasma-stimu-
lated solutions. Sci. Rep. 7, 4479.
Ye, F., Kaneko, H., Nagasaka, Y., Ijima, R., Nakamura, K., Nagaya, M.,
Takayama, K., Kajiyama, H., Senga, T., Tanaka, H., etal. (2015).
Plasma-activated medium suppresses choroidal neovascu-
larization in mice: a new therapeutic concept for age-related
macular degeneration. Sci. Rep. 5, 1–7.
Yousfi, M., Merbahi, N., Pathak, A., and Eichwald, O. (2014). Low-
temperature plasmas at atmospheric pressure: toward new
pharmaceutical treatments in medicine. Fundam. Clin. Pharma-
col. 28, 123–135.
Yue, Y., Pei, X., and Lu, X. (2016a). OH density optimization in atmos-
pheric-pressure plasma jet by using multiple ring electrodes.
J.Appl. Phys. 119, 033301.
Yue, Y., Xian, Y., Pei, X., and Lu, X. (2016b). The effect of three differ-
ent methods of adding O2 additive on O concentration of atmos-
pheric pressure plasma jets (APPJs). Phys. Plasmas 23, 123503.
Zhang, Q., Sun, P., Feng, H., Wang, R., Liang, L., Zhu, W., Becker, K.,
Zhang, J., and Fang, J. (2012). Assessment of the role of various
inactivation agents in an argon based direct current atmos-
pheric pressure cold plasma jet. J. Appl. Phys. 111, 123305.
Zhang, Q., Liang, Y., Feng, H., Ma, R., Tian, Y., Zhang, J., and Fang, J.
(2013). A study of oxidative stress induced by non-thermal plasma-
activated water for bacterial damage. Appl. Phys. Lett. 102, 1–4.
Zhang, Q., Ma, R., Tian, Y., Su, B., Wang, K., Yu, S., Zhang, J., and
Fang, J. (2016). Sterilization efficiency of a novel electrochemi-
cal disinfectant against Staphylococcus aureus. Environ. Sci.
Technol. 50, 3184–3192.
Zhang, S., Rousseau, A., and Dufour, T. (2017). Promoting lentil ger-
mination and stem growth by plasma activated tap water, dem-
ineralized water and liquid fertilizer. RSC Adv. 7, 31244–31251.
Bereitgestellt von | De Gruyter / TCS
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... Most of the plasma reactor geometries that have been considered in the past decade consist essentially of batch processes where the plasma is generated either above the surface of the liquid or inside it. These configurations have demonstrated the potential of cold plasma in agriculture and medicine [6][7][8]. Nevertheless, various attempts to achieve technological transfer have highlighted the limitations in the scalability of these reactors, especially due to the limit in species transfer between the plasma phase (where they are produced) and the liquid phase (where they are stored or used). ...
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Systems where cold atmospheric plasma interacts with liquid aerosols provide information on unexplored physico‐chemical phenomena and yield multiple advantages. Plasma‐activated aerosols show high chemical reactivity within small liquid microdroplet volumes, making them suitable for various applications and industrial processes. Plasma–aerosol interactions present complex interdisciplinary challenges that demand detailed investigations of the underlying physical, chemical, and transport mechanisms. This short review focuses on the key challenges in understanding plasma–aerosol interactions and the diagnostic hurdles in elucidating the physical and chemical mechanisms governing microdroplet interactions with plasma discharges. The scalability of plasma–aerosol systems, including high‐throughput charged water flows, are analyzed. Some “niche” applications of plasma–aerosols are identified, especially in decontamination, nitrogen fixation, and agriculture. The controversies in the field are also introduced and critically discussed. The review concludes with a proposed path and outlook for the development of plasma–aerosol technology.
... The pH value also plays a decisive role in determining the reactivity of the oxidants. Thus, plasma-treated water generated using CaviPlasma technology offers another advantage over the common plasma technologies producing plasma-activated water (Kaushik et al. 2019). ...
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We investigated the production of highly reactive oxygen species (ROS) in solutions undergoing treatment using CaviPlasma (CP) technology. This technology combines plasma discharge with hydrodynamic cavitation. This study focused on factors such as pH, conductivity, presence of salts and organic matter affecting ROS formation and their stability in solutions. Depending on the used matrix, CP produces 450–580 µg L⁻¹ s⁻¹ of hydrogen peroxide and 1.9 µg L⁻¹ s⁻¹ of hydroxyl radicals dissolved in liquid. Using cyanobacteria and cyanotoxins as example, we proved that CP technology is a highly efficient method for destroying microorganisms and persistent toxins. The biocidal effect of the CP treatment was confirmed on two species of cyanobacteria, Synechococcus elongatus and Merismopedia minutissima. The effectiveness of the technology in degrading microcystins was also demonstrated. The potential of this technology is based on its high energy efficiency, G(H2O2) ≈ 10 g kWh⁻¹ and G(O3) ≈ 0.03 g kWh⁻¹ (in deionised water), realistic applicability with throughput rates (> 1 m³ h⁻¹), and comparatively easy scalability system.
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This work quantifies, through use of molecular dynamics (MD) simulations, the kinetic rates of physical surface processes occurring at a plasma-water interface. The probabilities of adsorption, absorption, desorption and scattering...
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Molecular dynamics (MD) with the ReaxFF force field is used to study the structural damage to HIV capsid protein and gp120 protein mediated by reactive oxygen species (ROS). Our results show that with an increase in ROS concentration, the structures of the HIV capsid protein and gp120 protein are more severely damaged, including dehydrogenation, increase in oxygen-containing groups, helix shortening or destruction, and peptide bond breaking. In particular, we noticed that extraction of H atoms from N atoms by ROS was significantly higher than that from C atoms. There was no significant difference in the effect of ROS on dehydrogenation and shortening or breaking of the helices. In contrast, the impact of O on the increase in oxygen-containing groups and the fracture of peptide bonds in the gp120 protein is more significant than that of O3, and the effect of O3 is greater than that of ˙OH. In addition, the degree of structural damage of the gp120 protein was greater than that of the capsid protein. These detailed findings deepen our understanding of the role of ROS in regulating the structure and function of the HIV capsid protein and gp120 protein and provide valuable insights for plasma therapy for acquired immune deficiency syndrome (AIDS).
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Atmospheric pressure plasma jet (APPJ) is one of the primary sources to produce low-temperature plasmas that are commonly characterized with low gas temperature and high species reactivity, thus possessing wide application prospects in various fields including bio-medicine and materials. Compared to other low-temperature plasma sources such as parallel plate DBDs or surface DBDs, APPJs are featured with a plasma plume formed in ambient atmosphere other than confined in between electrodes, making it suitable for surface treatment, especially the one with complex surface morphology. Generally, APPJs can alter the surface properties via multiple physical and chemical mechanisms, such as surface charging, surface ionization waves, surface reactions, etc., and in turn, the surface properties, such as surface morphology, permittivity, and conductivity, could affect the discharge dynamics in APPJs. Interactions between APPJs and surfaces are therefore not only scientific issues on discharge plasma physics, but also technical challenges for specific applications, and gaining great research interests in the past three decades. In the present work, we aim to provide an educational review on the interactions between APPJs and surfaces, focusing on the physical, chemical and biological processes in both fundamental science and application engineering.
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Plasma‐treated liquids and their medical application have gained momentum in the fields of plasma science in recent years. Most research has been done in the field of cancer treatment. Another new and promising special field of CAP−liquid interaction is hydrogels, which can serve as localized reservoirs for the delivery of long‐lived reactive oxygen and nitrogen species and other active ingredients such as chemotherapeutic drugs. Identifying liquids and hydrogel compositions optimal for plasma treatment, for their reservoir function, and from a regulatory point of view for use in medicine, together with the chemical identification of biologically active molecules and interdependencies to plasma operation parameters, are the fundamental challenges in the field.
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This work concerned itself with the corona discharge powered by AC at atmospheric pressure and its effects on E. coli bacteria and organic pollutants in wastewater. An affordable disinfection plasma device with low energy consumption (<5 W) was designed, enabling the AC corona effect to be closely examined. The electric properties of the AC corona in the presence of water were studied using methods like Lissajous curves, time-dependant and flow-rate-dependant measurements, and electric field simulations in Python. Chemical reactions in the discharge were analyzed using FTIR and UV/Vis spectroscopy, measurements of the reactive oxygen and nitrogen species (RONS) both in the water and in the air, and simulations of rotational and vibrational temperatures. Results include the inactivation efficiency of E. coli by means of the AC corona as well as the partial effects of the individual mechanisms (heat, UV, RONS, etc.) The potential to degrade organic pollutants (drugs, psychoactive chemicals…) present in wastewater was examined, measuring reductions for over 110 pollutants.
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In this review, we give an overview of the applications of plasma activated water (PAW) and its chemistry in the field of agriculture. This article concentrates on the chemistry of long‐lived reactive species and their roles in plant cell mechanisms. The chemical reactions important for the creation of nitrate, nitrite, and hydrogen peroxide inside water during the production of PAW and their chemical paths inside the plant cells are discussed. We describe the use of different types of discharges for PAW production and present the results of PAW application to seeds and plants. We address the decontamination of agricultural chemicals in water along with the scarcely explored topic of water remediation. The major challenges and future possibilities for PAW in agriculture are also discussed.
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Despite ongoing food safety measures in the United States, foodborne illness continues to be a substantial health burden. The 10 U.S. sites of the Foodborne Diseases Active Surveillance Network (FoodNet)* monitor cases of laboratory-diagnosed infections caused by nine pathogens transmitted commonly through food. This report summarizes preliminary 2017 data and describes changes in incidence since 2006. In 2017, FoodNet reported 24,484 infections, 5,677 hospitalizations, and 122 deaths. Compared with 2014-2016, the 2017 incidence of infections with Campylobacter, Listeria, non-O157 Shiga toxin-producing Escherichia coli (STEC), Yersinia, Vibrio, and Cyclospora increased. The increased incidences of pathogens for which testing was previously limited might have resulted from the increased use and sensitivity of culture-independent diagnostic tests (CIDTs), which can improve incidence estimates (1). Compared with 2006-2008, the 2017 incidence of infections with Salmonella serotypes Typhimurium and Heidelberg decreased, and the incidence of serotypes Javiana, Infantis, and Thompson increased. New regulatory requirements that include enhanced testing of poultry products for Salmonella†might have contributed to the decreases. The incidence of STEC O157 infections during 2017 also decreased compared with 2006-2008, which parallels reductions in isolations from ground beef.§The declines in two Salmonella serotypes and STEC O157 infections provide supportive evidence that targeted control measures are effective. The marked increases in infections caused by some Salmonella serotypes provide an opportunity to investigate food and nonfood sources of infection and to design specific interventions.
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In recent years, plasma-activated solutions (PASs) have made good progress in the disinfection of medical devices, tooth whitening, and fruit preservation. In this study, we investigated the inactivation efficacy of Newcastle disease virus by PASs. Water, 0.9% NaCl, and 0.3% H2O2 were excited by plasma to obtain the corresponding solutions PAS(H2O), PAS(NaCl), and PAS(H2O2). The complete inactivation of virus after PAS treatment for 30 min was confirmed by the embryo lethality assay (ELA) and hemagglutination (HA) test. Scanning electron microscopy (SEM) results showed that the morphology of the viral particle changed under PAS treatments. The total protein concentration of virus decreased as measured by a Bradford protein assay due to PAS treatment. The nucleic acid integrity assay demonstrated that viral RNA degraded into smaller fragments. Moreover, the physicochemical properties of PASs, including the oxidation-reduction potential (ORP), electrical conductivity, and H2O2 concentration, and electron spin resonance spectra analysis indicated that reactive oxygen and nitrogen species play a major role in the virus inactivation. Therefore, the application of PASs, as an environmentally friendly method, would be a promising alternative strategy in poultry industries.
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Chemotherapy is an important treatment method for metastatic cancer, but the drug-uptake efficiency of cancer cells needs to be enhanced in order to diminish the side effects of chemotherapeutic drugs and improve survival. The use of a nonequilibrium low-temperature atmospheric-pressure plasma jet (APPJ) has been demonstrated to exert selective effects in cancer therapy and to be able to enhance the uptake of molecules by cells, which makes an APPJ a good candidate adjuvant in combination chemotherapy. This study estimated the effects of direct helium-based APPJ (He-APPJ) exposure (DE) and He-APPJ-activated RPMI medium (PAM) on cell viability and migration. Both of these treatments decreased cell viability and inhibited cell migration, but to different degrees in different cell types. The use of PAM as a culture medium resulted in the dialkylcarbocyanine (DiI) fluorescent dye entering the cells more efficiently. PAM was combined with the anticancer drug doxorubicin (Doxo) to treat human heptocellular carcinoma HepG2 cells and human adenocarcinomic alveolar basal epithelial A549 cells. The results showed that the synergistic effects of combined PAM and Doxo treatment resulted in stronger lethality in cancer cells than did PAM or Doxo treatment alone. To sum up, PAM has potential as an adjuvant in combination with other drugs to improve curative cancer therapies.
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Cold atmospheric plasmas (CAP) are weakly ionized gases that can be generated in ambient air. They produce energetic species (e.g. electrons, metastables) as well as reactive oxygen species, reactive nitrogen species, UV radiations and local electric field. Their interaction with a liquid such as tap water can hence change its chemical composition. The resulting "plasma-activated liquid" can meet many applications, including medicine and agriculture. Consequently, a complete experimental set of analytical techniques dedicated to the characterization of long lifetime chemical species has been implemented to characterize tap water treated using CAP process and intended to agronomy applications. For that purpose, colorimetry and acid titrations are performed, considering acid-base equilibria, pH and temperature variations induced during plasma activation. 16 species are quantified and monitored: hydroxide and hydronium ions, ammonia and ammonium ions, orthophosphates, carbonate ions, nitrite and nitrate ions and hydrogen peroxide. The related consumption/production mechanisms are discussed. In parallel, a chemical model of electrical conductivity based on Kohlrausch's law has been developed to simulate the electrical conductivity of the plasma-activated tap water (PATW). Comparing its predictions with experimental measurements leads to a narrow fitting, hence supporting the self-sufficiency of the experimental set. Finally, to evaluate the potential of cold atmospheric plasmas for agriculture applications, tap water has been daily plasma-treated to irrigate lentils seeds. Then, seedlings lengths have been measured and compared with untreated tap water, showing an increase as high as 34.0% and 128.4% after 3 days and 6 days of activation respectively. The interaction mechanisms between plasma and tap water are discussed as well as their positive synergy on agronomic results.
Article
Cell homeostasis is regulated by a balance between proliferation, growth arrest and programmed cell death (apoptosis). Until recently, studies on oncogenesis have focused on the regulation of cell proliferation. The recognition that negative growth control, including growth arrest and programmed cell death, must be understood to comprehend how appropriate cell numbers are maintained and how alterations in any part of the equation can contribute to malignancy has led to a burst of work in this field. This review focuses on what has been learned about distinct settings of negative growth control, analyzing p53-dependent and independent pathways of growth arrest and apoptosis either coupled or uncoupled from differentiation, with an emphasis on the use of hematopoietic cells. The importance of understanding the molecular biology of apoptotic and growth arrest pathways in cancer therapy, and future directions to study negative growth control are addressed as well.
Article
The interaction between cold atmospheric pressure plasma and liquids is receiving increasing interest for various applications. Specifically, the use of plasma-treated liquids (PTL) for biomedical applications is of growing importance, in particular for sterilization and cancer treatment. However, insight in the underlying mechanisms of plasma-liquid interaction is still scarce. Here, we present a 2D fluid dynamics model for the interaction between a plasma jet and liquid water. Our results indicate that the formed reactive species originate from either the gas phase (with further solvation) or are formed at the liquid interface. A clear increase in the aqueous density of H2O2, HNO2/NO2⁻ and NO3⁻ is observed as a function of time, while the densities of O3, HO2 and ONOOH are found to quickly reach a maximum due to chemical reactions in solution. The trends observed in our model correlate well with experimental observations from literature.
Article
Development of alternative, chemical-free approaches for control of postharvest fungi on a commercial scale has become a challenge for plant pathologists in recent years. Although there are several established techniques such as heat that are used as postharvest treatments, they often have disadvantages including alteration of food quality due to physiological responses to the treatment, or environment pollution. A promising new postharvest treatment is cold plasma, which is a gas-derived mix of atoms, excited molecules and charged particles. Cold plasma has no known adverse effects on fresh produce or the environment. It is an established technology in the medical field and has been demonstrated to successfully control bacterial pathogens that cause food safety issues. This review focuses on the potential of cold plasma technology for postharvest disease control, especially those caused by fungi. An overview of plasma generation systems is provided, and in vivo and in vitro research is reviewed to consider benefits, limitations and research gaps in the context of cold plasma as a potential method for controlling postharvest fungal pathogens. Finally, we provide recommendations for the application of this technology in commercial facilities.