![Mechanisms of cell damage by nanoparticles. (1) Physical damage of membranes [43, 67, 75]. (2) Structural changes in cytoskeleton components [45, 46]. (3) Disturbance of transcription and oxidative damage of DNA [61, 62]. (4) Damage of mitochondria [39, 40]. (5) Disturbance of lysosome functioning [51]. (6) Generation of reactive oxygen species [61]. (7) Disturbance of membrane protein functions [172]. (8) Synthesis of inflammatory factors and mediators [54, 55]](https://www.researchgate.net/publication/322999955/figure/fig1/AS:591593895653376@1518058384373/Mechanisms-of-cell-damage-by-nanoparticles-1-Physical-damage-of-membranes-43-67_Q320.jpg)
Available via license: CC BY 4.0
Content may be subject to copyright.
N A N O R E V I E W Open Access
Dependence of Nanoparticle Toxicity on
Their Physical and Chemical Properties
Alyona Sukhanova
1,2*
, Svetlana Bozrova
2
, Pavel Sokolov
2
, Mikhail Berestovoy
2
, Alexander Karaulov
3
and Igor Nabiev
1,2*
Abstract
Studies on the methods of nanoparticle (NP) synthesis, analysis of their characteristics, and exploration of new fields
of their applications are at the forefront of modern nanotechnology. The possibility of engineering water-soluble
NPs has paved the way to their use in various basic and applied biomedical researches. At present, NPs are used in
diagnosis for imaging of numerous molecular markers of genetic and autoimmune diseases, malignant tumors, and
many other disorders. NPs are also used for targeted delivery of drugs to tissues and organs, with controllable
parameters of drug release and accumulation. In addition, there are examples of the use of NPs as active components,
e.g., photosensitizers in photodynamic therapy and in hyperthermic tumor destruction through NP incorporation and
heating. However, a high toxicity of NPs for living organisms is a strong limiting factor that hinders their use in vivo.
Current studies on toxic effects of NPs aimed at identifying the targets and mechanisms of their harmful effects are
carried out in cell culture models; studies on the patterns of NP transport, accumulation, degradation, and elimination,
in animal models. This review systematizes and summarizes available data on how the mechanisms of NP toxicity for
living systems are related to their physical and chemical properties.
Keywords: Nanoparticles, Quantum dots, Nanotoxicity, Surface chemistry, Theranostics, Imaging
Background
The International Organization for Standardization de-
fine nanoparticles (NPs) as structures whose sizes in
one, two, or three dimensions are within the range from
1 to 100 nm. Apart from size, NPs may be classified in
terms of their physical parameters, e.g., electrical charge;
chemical characteristics, such as the composition of the
NP core or shell; shape (tubes, films, rods, etc.); and
origin: natural NPs (NPs contained in volcanic dust, viral
particles, etc.) and artificial NPs, which are the focus of
this review.
Nanoparticles have become widely used in electronics,
agriculture, textile production, medicine, and many
other industries and sciences. NP toxicity for living
organisms, however, is the main factor limiting their use
in treatment and diagnosis of diseases. At present, re-
searchers often face the problem of balance between the
positive therapeutic effect of NPs and side effects related
to their toxicity. In this respect, the choice of an
adequate experimental model for estimating toxicity be-
tween in vitro (cell lines) and in vivo (experimental ani-
mals) ones is of paramount importance. The NP toxic
effects on individual cell components and individual
tissues are easier to analyze in in vitro models, whereas
in vivo experiments make it possible to estimate the NP
toxicity for individual organs or the body as a whole. In
addition, the possible toxic effect of NPs depends on
their concentration, duration of their interaction with
living matter, their stability in biological fluids, and
the capacity for accumulation in tissues and organs.
Development of safe, biocompatible NPs that can be
used for diagnosis and treatment of human diseases
can only be based on complete understanding of the
interactions between all factors and mechanisms
underlying NP toxicity.
Medical Applications of Nanoparticles
In medicine, NPs can be used for diagnostic or thera-
peutic purposes. In diagnosis, they can serve as fluores-
cent labels for detection of biomolecules and pathogens
* Correspondence: alyona.sukhanova@univ-reims.fr;igor.nabiev@univ-reims.fr
1
Laboratoire de Recherche en Nanosciences, LRN-EA4682, Université de
Reims Champagne-Ardenne, 51100 Reims, France
Full list of author information is available at the end of the article
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.
Sukhanova et al. Nanoscale Research Letters (2018) 13:44
https://doi.org/10.1186/s11671-018-2457-x
and as contrast agents in magnetic resonance and other
studies. In addition, NPs can be used for targeted delivery
of drugs, including protein and polynucleotide substances;
in photodynamic therapy and thermal destruction of tu-
mors, and in prosthetic repair [1–6]. Some types of NPs
are already successfully used in clinic for drug delivery
and tumor cell imaging [7–9].
Examples of the use of gold NPs have been accumu-
lating recently. They have proved to be efficient carriers
of chemotherapeutics and other drugs. Gold NPs are
highly biocompatible; however, although gold as a sub-
stance is inert towards biological objects, it cannot be
argued that the same is true for gold NPs, since there
are no conclusive data yet on the absence of delayed
toxic effects [10]. In addition to gold NPs, those based
on micelles, liposomes [11], and polymers with attached
“capture molecules”[12] are already used as drug car-
riers. Single- and multiwalled nanotubes are good ex-
amples of NPs used for drug delivery. They are suitable
for attaching various functional groups and molecules
for targeted delivery, and their unique shape allows
them to selectively penetrate through biological barriers
[13]. The use of NPs as vehicles for drugs enhances the
specificity of delivery and decreases the minimum
amount of NPs necessary for attaining and maintaining
the therapeutic effect, thereby reducing the eventual
toxicity. This is especially important in the case of
highly toxic and short-lived chemo- and radiothera-
peutic agents [14].
Quantum dots (QDs) constitute another group of NPs
with a high potential for clinical use. QDs are semicon-
ductor nanocrystals from 2 to 10 nm in size. Their
capacity for fluorescence in different spectral regions, in-
cluding the infrared one [15], makes them suitable for
labeling and imaging cells, cell structures, or pathogenic
biological agents, as well as various processes in cells,
tissues, and body as a whole [16–18], which has import-
ant diagnostic implications [19,20]. NPs based on super-
paramagnetic iron oxide are efficiently used as contrast
agents in magnetic resonance tomography (MRT) for
imaging liver, bone marrow, and lymph node tissues
[21]. There is also an example where radioactively la-
beled single-walled carbon nanotubes functionalized
with phospholipids were used for labeling integrin-
containing tumors and their subsequent detection by
means of positron emission tomography in experiments
on mice [22].
Nanoparticles have also been used in designing biosen-
sors, including those based on carbon nanotubes for
measuring the glucose level [23], detecting specific DNA
fragments and regions [24], and identifying bacterial
cells [25].
Silver (or silver-containing) NPs exert antimicrobial
and cytostatic effects; for this reason, they are widely
used in medicine, e.g., for treating bandages, surgical in-
struments, prostheses, and contraceptives [13,22]. Silver
NPs have been reported to serve as effective and safe
preservation agents in the cosmetic industry [26].
However, NPs may still be highly toxic, even if the
safety of using many of their chemical constituents in
medicine has been proved. The toxic effect may be
caused by their unique physical and chemical properties,
which underlie specific mechanisms of interaction with
living systems. In general, this determines the import-
ance of studying the causes and mechanisms of the po-
tential toxic effect of NPs.
Mechanisms of Nanoparticle Toxicity
ThetoxicityofNPsislargelydeterminedbytheir
physical and chemical characteristics, such as their
size, shape, specific surface area, surface charge, cata-
lytic activity, and the presence or absence of a shell
and active groups on the surface.
The small size of NPs allows them to penetrate
through epithelial and endothelial barriers into the
lymph and blood to be carried by the bloodstream
and lymph stream to differentorgansandtissues,in-
cluding the brain, heart, liver, kidneys, spleen, bone
marrow, and nervous system [27,28], and either be
transported into cells by transcytosis mechanisms or
simply diffuse into them through the cell membrane.
Nanomaterials can also increase access to the blood
stream through ingestion [29,30]. Some nanomater-
ials can penetrate the skin [31,32] and even greater
microparticles can penetrate skin when it is flexed
[33]. Nanoparticles, because of their small size, can
extravasate through the endothelium in inflammatory
sites, epithelium (e.g., intestinal tract and liver), tu-
mors or penetrate microcapillaries [34]. Experiments
modeling the toxic effects of NPs on the body have
shown that NPs cause thrombosis by enhancing plate-
let aggregation [35], inflammation of the upper and
lower respiratory tracts, neurodegenerative disorders,
stroke, myocardial infarction, and other disorders
[36–38]. Note that NPs may enter not only organs,
tissues, and cells, but also cell organelles, e.g., mito-
chondria and nuclei; this may drastically alter cell
metabolism and cause DNA lesions, mutations, and
cell death [39].
The toxicity of QDs has been shown to be directly re-
lated to the leakage of free ions of metals contained in
their cores, such as cadmium, lead, and arsenic, upon
oxidation by environmental agents. QDs may be
absorbed by mitochondria and cause morphological
changes and dysfunction of the organelles [40]. Entry of
cadmium-based QDs into cells and formation of free
Cd
2+
ions causes oxidative stress [41,42].
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 2 of 21
Recent studies have shown that contact of lung tissue
with NPs about 50 nm in size leads to perforation of the
membranes of type I alveolar cells and the resultant
entry of the NPs into the cells. This, in turn, causes cell
necrosis, as evidenced by the release of lactate dehydro-
genase [43]. There is evidence that QD penetration in-
creases the cell membrane fluidity [44]. On the other
hand, the formation of reactive oxygen species (ROS) in-
duced by peroxidation of membrane lipids may lead to
the loss of membrane flexibility, which, as well as an ab-
normally high fluidity, inevitably results in cell death.
Interaction of NPs with the cytoskeleton may also
damage it. For example, TiO
2
NPs induce conform-
ational changes in tubulin and inhibit its polymerization
[45], which disturbs intracellular transport, cell div-
ision, and cell migration. In human umbilical vein
endothelial cells (HUVECs), damage of the cytoskel-
eton hinders the maturation of coordination adhesive
complexes which link the cytoskeleton to the extra-
cellular matrix, thereby disturbing the formation of
the vascular network [46].
In addition, the NP cytotoxicity may interfere with
cell differentiation and protein synthesis, as well as
activate proinflammatory genes and synthesis of in-
flammatory mediators. It should be specially noted
that normal protective mechanisms do not affect NPs;
macrophage uptake of large PEGylated nanoparticles
is more efficient than uptake of small ones, which
leads to accumulation of NPs in the body [47]. Super-
paramagnetic iron oxide NPs have been demonstrated
to disturb or entirely suppress osteogenic differenti-
ation of stem cells and activate the synthesis of signal
molecules, tumor antigens, etc. [48,49]. In addition,
interaction of NPs with the cell enhances the expres-
sion of the genes responsible for the formation of ly-
sosomes [50], disturbs their functioning [51], and
inhibits protein synthesis [52,53]. A study on the
toxic effects of NPs of different compositions on lung
epithelial cells and human tumor cell lines has shown
that NPs stimulate the synthesis of inflammation me-
diators, e.g., interleukin 8 [54]. According to Park,
who studied the expression of proinflammatory cyto-
kines in vitro and in vivo, the expressions of interleu-
kin 1 beta (IL-1β) and tumor necrosis factor alpha
(TNFα) are enhanced in response to silicon NPs [55].
Oxidation, as well as action of various enzymes on the
shell and surface of NPs, results in their degradation and
release of free radicals. In addition to the toxic effect of
free radicals expressed as oxidation and inactivation of en-
zymes, mutagenesis, and disturbance of chemical reac-
tions leading to cell death, degradation of NPs leads to
alteration or loss of their own functionality (e.g., the loss
of the magnetic moment and the changes in the fluores-
cence spectrum and transport or other functions) [56,57].
In summary, the most common mechanisms of NP
cytotoxicity are the following:
1. NPs may cause oxidation via formation of ROS and
other free radicals;
2. NPs may damage cell membranes by perforating them;
3. NPs damage components of the cytoskeleton,
disturbing intracellular transport and cell division;
4. NPs disturb transcription and damage DNA, thus
accelerating mutagenesis;
5. NPs damage mitochondria and disturb their
metabolism, which leads to cell energy imbalance;
6. NPs interfere with the formation of lysosomes,
thereby hampering autophagy and degradation of
macromolecules and triggering the apoptosis;
7. NPs cause structural changes in membrane proteins
and disturb the transport of substances into and out
of cells, including intercellular transport;
8. NPs activate the synthesis of inflammatory
mediators by disturbing the normal mechanisms of
cell metabolism, as well as tissue and organ
metabolism (Fig. 1).
Although there are numerous mechanisms of NP toxi-
city, it is necessary to determine and classify the type
and mechanism of each particular toxic effect of NPs as
dependent on their physical and chemical properties.
Relationships of Nanoparticle Toxicity with Their Physical
and Chemical Properties
The toxicity of NPs is considered to depend on their
physical and chemical characteristics, including the size,
Fig. 1 Mechanisms of cell damage by nanoparticles. (1) Physical
damage of membranes [43,67,75]. (2) Structural changes in
cytoskeleton components [45,46]. (3) Disturbance of transcription and
oxidative damage of DNA [61,62]. (4) Damage of mitochondria [39,40].
(5) Disturbance of lysosome functioning [51]. (6) Generation of reactive
oxygen species [61]. (7) Disturbance of membrane protein functions
[172]. (8) Synthesis of inflammatory factors and mediators [54,55]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 3 of 21
shape, surface charge, chemical compositions of the core
and shell, and stability. In particular, Oh et al., using the
data meta-analysis of 307 papers describing 1741 cell
viability-related data samples, recently analyzed the
CdSe quantum dot toxicity. It has been shown that the
QD nanotoxicity is closely correlated with their surface
properties (including shell, ligand, and surface modifica-
tions), diameter, toxicity assay type used, and the exposure
time [58]. Which of these factors is the most important is
determined by the specific experimental task and model;
therefore, we will now consider each factor separately.
Nanoparticle Size and Toxicity
The NP size and surface area play an important role,
largely determining the unique mechanism of NP inter-
action with living systems. NPs are characterized by a
very large specific surface area, which determines their
high reaction capacity and catalytic activity. The sizes of
NPs (from 1 to 100 nm) are comparable with the size of
protein globules (2–10 nm), diameter of DNA helix
(2 nm), and thickness of cell membranes (10 nm), which
allows them to easily enter cells and cell organelles. For
example, Huo et al. have demonstrated that gold NPs no
larger than 6 nm effectively enter the cell nucleus,
whereas large NPs (10 or 16 nm) only penetrate through
the cell membrane and are found only in the cytoplasm.
This means that NPs several nanometers in size are
more toxic than 10 nm or larger NPs, which cannot
enter the nucleus [59]. Pan et al. have traced the de-
pendence of the toxicity of gold NPs on their size in the
range from 0.8 to 15 nm. The NPs 15 nm in size have
been found to be 60 times less toxic than 1.4-nm NPs
for fibroblasts, epithelial cells, macrophages, and melan-
oma cells. It is also noteworthy that 1.4-nm NPs cause
cell necrosis (within 12 h after their addition to the cell
culture medium), whereas 1.2-nm NPs predominantly
cause apoptosis [60]. These data suggest not only that
NPs can enter the nucleus, but also that the correspond-
ence of the geometric size of NPs (1.4 nm) to that of the
major groove of DNA allows them to effectively interact
with the negatively charged sugar–phosphate DNA
backbone and block the transcription [61,62].
In addition, the NP size largely determines how the
NPs interact with the transport and defense systems of
cells and the body. This interaction, in turn, affects the
kinetics of their distribution and accumulation in the
body. The review paper by [63] presents both theoretical
considerations and numerous experimental data demon-
strating that NPs smaller than 5 nm usually overcome
cell barriers nonspecifically, e.g., via translocation,
whereas larger particles enter the cells by phagocytosis,
macropinocytosis, and specific and nonspecific transport
mechanisms. An NP size of about 25 nm is believed to
be optimal for pinocytosis, although this also strongly
depends on the cell size and type [63,64]. In vivo experi-
ments have shown that NPs smaller than 10 nm are
rapidly distributed among all organs and tissues upon
intravenous administration, whereas most larger NPs
(50–250 nm) are found in the liver, spleen, and blood
[65]. This suggests that large NPs are recognized by spe-
cific defense systems of the body and absorbed by the
system of mononuclear phagocytes, which prevents
them from entering other tissues. In addition, Talamini
et al. claimed that the NP size and shape influence the
kinetics of accumulation and excretion of gold NPs in
filter organs, and only star-like gold NPs are able to ac-
cumulate in the lung. They have also shown that the
changes in the NP geometry do not improve the NP pas-
sage of the blood–brain barrier [66].
The large specific surface area ensures effective ad-
sorption of NPs on the cell surface. This was shown in a
study on the hemolytic activity of 100- to 600-nm meso-
porous silicon particles towards human erythrocytes
[67]. The particles 100 nm in size were effectively
adsorbed on the erythrocyte surface without causing cell
destruction or any morphological changes in the cells,
whereas 600-nm particles deformed the membrane and
entered the cells, resulting in erythrocyte destruction
(hemolysis) [67].
Nanoparticle Shape and Toxicity
The characteristic shapes of NPs are spheres, ellipsoids,
cylinders, sheets, cubes, and rods. NP toxicity strongly
depends on their shape. This has been shown for numer-
ous NPs of different shapes and chemical compositions
[68–71]. For example, spherical NPs are more prone to
endocytosis than nanotubes and nanofibers [72]. Single-
walled carbon nanotubes have been found to more ef-
fectively block calcium channels compared to spherical
fullerenes [73].
Comparison of the effects of hydroxyapatite NPs with
different shapes (needle-like, plate-like, rod-like, and
spherical) on cultured BEAS-2B cells have shown that
plate-like and needle-like NPs cause death of a larger
proportion of cells than spherical and rod-like NPs [74].
This is partly accounted for by the capacity of plate-like
and needle-like NPs for damaging cells and tissue upon
direct contact. Hu et al. [75] obtained interesting data
when studying the damage of mammalian cells by gra-
phene oxide nanosheets. The toxicity of these NPs was
determined by their shape allowing them to physically
damage the cell membrane. However, their toxicity was
found to decrease with an increase in the fetal calf
serum concentration in the culture medium. This was
explained by a high capacity of graphene oxide NPs for
adsorbing protein molecules, which cover the NP sur-
face, thereby changing the shape of the NPs and partly
preventing the damage of cell membranes [75].
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 4 of 21
Nanoparticle Chemical Composition and Toxicity
Although the toxicity of NPs strongly depends on their
size and shape, the influence of other factors, such as
the NP chemical composition and crystal structure,
should not be disregarded. Comparison of the effects of
20-nm silicon dioxide (SiO
2
) and zinc oxide (ZnO) NPs
on mouse fibroblasts has shown that they differ in the
mechanisms of toxicity. ZnO NPs cause oxidative stress,
whereas SiO
2
NPs alter the DNA structure [76].
The toxicity of NPs is indeed largely determined by
their chemical composition. It has been shown that deg-
radation of NPs can occur, and its extent depends on the
environment conditions, e.g., pH or ionic strength. The
most common cause of the toxic effect of NPs interact-
ing with cells is leakage of metal ions from the NP core.
The toxicity also depends on the composition of the
core of NPs. Some metal ions, such as Ag and Cd, are in
fact toxic and, therefore, cause damage of the cells.
Other metal ions, such as Fe and Zn, are biologically
useful, but, at high concentrations, they could damage
cellular pathways and, hence, cause high toxicity. How-
ever, this effect can be decreased, e.g., by coating NP
cores with thick polymer shells, silica layers, or gold
shells instead of short ligands or by using nontoxic com-
pounds for NP synthesis. On the other hand, the com-
position of the core could be altered by addition of other
metals. This can result in enhanced chemical stability
against NP degradation and metal ion leakage into the
body [77].
The toxicity of NPs also depends on their crystal
structure. The relationship between crystal structure and
toxicity has been studied using a human bronchial epi-
thelium cell line and titanium oxide NPs with different
types of crystal lattice. It has been demonstrated that
NPs with a rutile-like crystal structure (prism-shaped
TiO
2
crystals) cause oxidative damage of DNA, lipid per-
oxidation, and formation of micronuclei, which indicates
abnormal chromosome segregation during mitosis,
whereas NPs with anatase-like crystal structure (octahe-
dral TiO
2
crystals) of the same size are nontoxic [78]. It
should be noted that the NP crystal structure may vary
depending on the environment, e.g., upon interaction
with water, biological fluids, or other dispersion media.
There is evidence that the crystal lattice of ZnS NPs is
rearranged into a more ordered structure upon contact
with water [79].
Nanoparticle Surface Charge and Toxicity
The surface charge of NPs plays an important role in
their toxicity, because it largely determines the interac-
tions of NPs with biological systems [80,81].
NP surfaces and their charges could be modified by
grafting differently charged polymers. PEG (polyethylene
glycol) or folic acid is often used to improve the NP
intracellular uptake and ability to target specific cells
[82]. The synthesis of biocompatible TiO2 nanoparticles
containing functional NH2 or SH groups has also been
reported [83]. Other substances, such as methotrexate,
polyethyleneimine, and dextran, had also been used to
modify NP surfaces and their charge [84].
A high toxicity of positively charged NPs is explained
by their ability to easily enter cells, in contrast to nega-
tively charged and neutral NPs. This is accounted for by
electrostatic attraction between the negatively charged
cell membrane glycoproteins and positively charged
NPs. Comparison of the cytotoxic effects of negatively
and positively charged polystyrene NPs on HeLa and
NIH/3T3 cells has shown that the latter NPs are more
toxic. This is not only because positively charged NPs
more effectively penetrate through the membrane, but
also because they are more strongly bound to the nega-
tively charged DNA, causing its damage and, as a result,
prolongation of the G0/G1 phase of the cell cycle. Nega-
tively charged NPs have no effect on the cell cycle [85].
Similar results have been obtained for positively and nega-
tively charged gold NPs, positive NPs being absorbed by
cells in larger amounts and more rapidly than negative
ones and being more toxic [86].
Positively charged NPs have an enhanced capacity for
opsonization, i.e., adsorption of proteins facilitating
phagocytosis, including antibodies and complement
components, from blood and biological fluids [87]. The
adsorbed proteins, referred to as the protein crown, may
affect the surface properties of NPs. For example, they
may alter the surface charge, aggregation characteristics,
and/or hydrodynamic diameter of NPs. In addition, ad-
sorption of proteins on the NP surface leads to their
conformational changes, which may decrease or com-
pletely inhibit the functional activities of the adsorbed
proteins. The protein crown mainly consists of major
serum proteins, such as albumin, fibrinogen, and im-
munoglobulin G, as well as other effector, signal, and
functional molecules [88,89]. Binding to NPs alters the
protein structure, which leads to the loss of their enzym-
atic activity, disturbance of biological processes, and pre-
cipitation of ordered polymeric structures, e.g., amyloid
fibrils [90]. This may lead to various diseases, such as
amyloidosis. In vitro experiments have demonstrated
that QDs coated with a hydrophilic polymer accelerate
the formation of fibrils of human β
2
microglobulin,
which are then arranged into multilayered structures on
the particle surface; this results in a local increase in the
protein concentration on the NP surface, precipitation,
and formation of oligomers [91].
Xu et al. developed a method for changing the NP
charge from negative to positive via various modifica-
tions of the surface. For example, polymer NPs were
modified with a pH-sensitive polymer so that, being
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 5 of 21
negatively charged in a neutral medium, they acquired a
positive charge in an acid medium, at pH 5–6[92]. This
technique makes it possible to substantially increase the
rate of NP uptake by cells, which could be used for drug
delivery to tumor cells. Estimation of the cytotoxicity of
surface-modified cerium oxide NPs for H9C2, HEK293,
A549, and MCF-7 cells has shown that basically different
biological and toxic effects can be obtained by using dif-
ferent polymers to make the NPs positively or negatively
charged or neutral. Specifically, positively charged and
neutral NPs are absorbed by all cell types at the same
rate, whereas negatively charged ones predominantly
accumulate in tumor cells [93]. Thus, modification of
the NP charge allows their localization and toxicity to
be controlled, which could be used for developing ef-
fective systems for delivery of chemotherapeutic drugs
to tumors.
Nanoparticle Shell and Toxicity
Application of a shell onto the surface of NPs is
necessary for changing their optical, magnetic, and
electrical properties; it is used for improving NP bio-
compatibility and solubility in water and biological
fluids by decreasing their aggregation capacity, in-
creasing their stability, etc. Thus, the shell decreases
the toxicity of NPs and provides them with the cap-
acity for selective interaction with different types of
cells and biological molecules.Inaddition,theshell
considerably influences the NP pharmacokinetics,
changing the patterns of NP distribution and accu-
mulation in the body [94].
As noted above, NP toxicity is largely related to the
formation of free radicals [40,57,95,96]. However, the
shell can considerably mitigate or eliminate this negative
effect, as well as stabilize NPs, increase their resistance
to environmental factors, decrease the release of toxic
substances from them, or make them tissue-specific
[97]. For example, Cho et al. modified polymer NPs by
coating them with lectins. The modified NPs selectively
bound with tumor cells presenting sialic acid molecules
on the surface, which made the NPs suitable for specific-
ally labeling cancer cells [98].
The NP surface can be modified with both organic
and inorganic compounds, e.g., polyethylene glycol,
polyglycolic acid, polylactic acid, lipids, proteins, low
molecular weight compounds, and silicon. This variety
of modifiers makes it possible to form complex systems
on the NP surface for changing the NP properties and
for their specific transport and accumulation.
Nanoparticles coated with shells of synthetic polymers
are used for delivery of antigens, thus serving as adju-
vants boosting the immune response. This allows obtain-
ing vaccines against the antigens that are targets of
strong natural nonspecific cellular immunity [99].
The shell is often used for improving solubilization
and decreasing the toxicity of QDs, because their metal
cores are hydrophobic and mainly consist of toxic heavy
metals, such as cadmium, tellurium, and mercury. The
shell increases the stability of the QD core and pre-
vents its desalination and oxidative or photolytic deg-
radation. This, in turn, decreases the leakage of metal
ions outside of the QD core and, hence, the toxicity of
QDs [100–102].
Study of Nanoparticle Toxicity
During the past two decades, the use of NPs has tremen-
dously extended and led to the foundation of nanotoxi-
cology, a new science studying the potential toxic effects
of NPs on biological and ecological systems. The general
goal of nanotoxicology is to develop the rules of synthe-
sis of safe NPs [103]. This calls for a comprehensive, sys-
temic approach to analysis of the toxic properties of NPs
and their effects on cells, tissues, organs, and the body
as a whole.
There are two routine approaches to the study of the
effects of various substances on living systems, which
are also applicable to NP toxic effects: in vitro experi-
ments on model cell lines and in vivo experiments on la-
boratory animals. We do not consider here the third
possible approach to estimating NP toxicity, computer
simulation, because the pathways and mechanisms of
the toxic effects of NPs are not known well enough for a
computer model to predict the consequences of interac-
tions between NPs and living matter for a wide range of
NPs with sufficient reliability.
Both cell culture and animal experimental models for
studying NP toxicity have their specific advantages and
disadvantages. The former allow deeper insight into the
molecular mechanisms of toxicity and identification of
the primary targets of NPs; however, the patterns of the
distribution of NPs in the body and their transport to
different tissues and cells are not taken into consider-
ation. The study of NP toxicity in animal experiments al-
lows the delayed effects of NP action in vivo to be
estimated. However, the general pattern of toxicity mani-
festations becomes so complicated that it is impossible
to determine which of them is the primary cause of the
observed effect and which are its consequences.
Study of Toxicity in Cell Cultures
Many studies of NP toxicity are carried out in primary
cell cultures serving as models of various types of hu-
man and animal tissues. In some cases, tumor cell lines
are used, e.g., for estimating the toxic effects of NPs used
in cancer chemotherapy. The type of cells is selected ac-
cording to the potential route by which NPs enter the
body. This may be oral uptake (mainly by ingestion),
transdermal uptake (through the skin surface), inhalation
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 6 of 21
uptake of NPs contained in the breathing air, or
intentional NP injection in clinic. Intestinal epithelium
cells (Caco-2, HT29, and SW480) are often used in ex-
perimental models for studying the toxicity of ingested
NPs (Table 1). In these models, the kinetics of NP up-
take by cells and the viability of cells upon the NP up-
take are studied.
The NPs that serve as carriers of drugs or contrast
agents, or those used for imaging, are administered by
injection. The toxicity of these NPs is studied in primary
blood cell cultures. Most commonly, hemolysis, platelet
activation, and platelet aggregation are estimated. In
addition to primary blood cell cultures, cultured
HUVECs, mesenchymal stem cells, mononuclear blood
cells, and various tumor cell lines (HeLa, MCF-7, PC3,
C4-2, and SKBR-3) are used (Table 2).
The toxicity of inhaled NPs is studied using the cell
lines modeling different tissues of the respiratory system,
e.g., A549 and C10 cells of pulmonary origin, alveolar
macrophages (RAW 264.7), various epithelial cells and
fibroblasts (BEAS-2B, NHBE, 16-HBE, SAEC), as well as
human monocytes (THP-1) (Table 3).
The toxicity of NPs that enter the body transdermally
is usually studied in keratinocytes, fibroblasts, and, more
rarely, sebocytes (cells of sebaceous glands) (Table 4).
Co-cultured Cell Lines and 3D Cell Cultures
Although the majority of in vitro nanotoxicity studies
are carried out on cell monocultures, studies using two
other approaches are increasingly often reported in the
literature. One of them is co-culturing of several types of
cells; the other is the use of 3D cultures. The rationale
for these approaches is the need for more realistic
models of mammalian tissues and organs. For example,
co-cultured Caco-2 epithelial colorectal adenocarcinoma
cells and Raji cells (a lymphoblast cell line) have served
as a model of the human intestinal epithelium in experi-
ments on the toxicity of silver NPs [104]. A co-culture
of three cell lines derived from lung epithelial cells, hu-
man blood macrophages, and dendritic cells has been
used as an experimental model in a study on the toxic
effects of inhaled NPs [105]. A model of skin consisting
of co-cultured fibroblasts and keratinocytes has been
suggested [106].
It is known that the cell phenotype, as well as cell
functions and metabolic processes, is largely determined
by the complex system of cell interactions with other
cells and the surrounding extracellular matrix [107].
Therefore, many important characteristics of cells with
an adhesive type of growth in a monolayer culture sub-
stantially differ from those of the same cells in the living
tissue; hence, conclusions from many experiments on
the NP toxic effects on cells growing in a monolayer are
somewhat incorrect [108]. Experimental 3D models of
tissues and organs have been used for analysis of NP
toxicity and penetration into cells in several published
studies. For example, there are 3D models based on
polymer hydrogels [109] and models constructed in spe-
cial perfusion chambers containing a semipermeable
membrane to which the cells are attached. Li et al. and
Lee et al. [110,111] used multicellular spheroids about
100 μm in size to obtain a 3D model of the liver and
compare the toxicities of CdTe and Au NPs in experi-
ments on this model and a monolayer culture of liver
cells [111]. The results obtained using the 3D model
were more closely correlated with the data obtained in
experiments on animals, which indicates a considerable
potential of this approach for adequate and informative
testing of NP toxicity.
In vivo Study of Nanoparticle Toxicity
In addition to the study of multilayered and 3D cell cul-
tures, the behavior of NPs in the living body is being ex-
tensively studied. Since these studies are focused on the
biomedical applications of NPs, the NP toxicity for living
organisms remains an important issue. Although NPs
are highly promising for various clinical applications,
they are potentially hazardous. This hazard cannot be
estimated correctly in vitro, following from the compari-
son of the in vivo and in vitro effects of NPs.
Titanium dioxide (TiO
2
) particles are among the most
widely used NPs, in particular, in environment protec-
tion measures. Therefore, it was exceptionally important
to estimate their toxicity in the case of a 100% bioavail-
ability, namely, in experiments with their intravenous in-
jection to experimental animals. This study has been
performed by Fabian et al. [112]. Experimental animals
(rats) were injected with a suspension of TiO
2
NPs at a
dose of 5 mg/kg, and their biodistribution, as well as the
general condition of the animals, was monitored. The re-
sults have shown that the animals exhibit no signs of ail-
ment or disorder, nor is inflammation or another
manifestation of a toxic effect observed, within 28 days.
This suggests that TiO
2
NPs are relatively harmless.
Silver NPs are another example of NPs potentially use-
ful in medicine, owing to their antimicrobial activity.
Their toxicity and biodistribution were analyzed in an
experiment where CD-1 mice were intravenously
injected with 10 mg/kg of silver NPs of different sizes
(10, 40, and 100 nm) coated with different shells. Al-
though each type of NPs was found to cause toxic dam-
age of tissues, larger particles were less toxic, probably,
due to their lower penetration capacity [113]. Asare et
al. [114] estimated the genotoxicity of silver and titan-
ium NPs administered at a dose of 5 mg/kg. They have
found that silver NPs cause DNA strand breaks and oxi-
dation of purine bases in the tissues examined. Gold
nanoparticles have a similar effect [115]. They have been
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 7 of 21
Table 1 Results of estimation of nanoparticle toxicity in experimental models of their oral uptake
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
Ag, TiO2, and ZnO NPs Ag, 20–30 nm
TiO2, 21 nm ZnO,
20 nm
0.1, 1, 10, and 100 mg/ml;
24 and 48 h
Caco-2
SW480
МТТ assay; ELISA;
LDH assay; ROS assay
Cell death (ZnO NPs are more toxic).
ROS production.
Release of IL-8 (Caco-2 cells produce
more IL-8 than SW480 cells).
[136]
Latex NPs and microbeads 50 nm and 100 nm 10–1000 μg/ml; 4 h Caco-2
Calu-3
MTS assay; LDH assay;
transepithelial electrical
resistance measurement;
confocal microscopy
Cell death (positively charged NPs
are more toxic). Release of LDH
from cells.
Penetration of the NPs into cells.
Transport of the NPs through the
epithelium layer (16–24% of the
microbeads and < 5% of the NPs
entering a cell monolayer are
transported through it).
[137]
Spherical (SNPs) and
rod-shaped (RNPs) CuO NPs
SNPs: diameter,
40 ± 16 nm RNPs:
thickness, 10 ± 3 nm;
length, 74 ± 17 nm
5–100 mg/ml; 24, 48,
and 120 h
Caco-2
A549
SZ95
N-hTERT
MTS assay; PCR;
immunoblotting; ELISA
Decreased cell viability (RNPs
are more toxic).
Expression of genes encoding
proinflammatory cytokines.
The transcript profile varies
depending on the type of
NPs: CD3E in the case of RNPs;
IL-1a, IL-9, and CD86 in the case
of SNPs.
[138]
CdTe QDs 3.5–4.5 nm 1, 0.1, and 0.01 mg/l;
24 h
Caco-2 Fluorescent microscopy;
transepithelial electrical
resistance measurement
Cell death related to penetration
of QDs into them.
Decreased TEER at a QD
concentration of 0.1 mg/l.
[139]
MgO, ZnO, SiO2, TiO2, and
carbon black NPs
MgO, 8 nm
ZnO, 10–20 nm
SiO2, 14 nm
TiO2, ˂10–300 nm
Carbon black, 14 nm
20 and 80 mg/cm2;
24 h
Caco-2 WST-1; LDH assay; DNA
comet assay; glutathione
level measurement
Decreased cell viability.
Release of LDH from cells.
Double-strand DNA breaks
and oxidative damage of DNA.
Decreased glutathione level.
[140]
Ag nanorods Length-to-diameter
ratio, 4:1
0.4 nM; 4 days HT29 МТТ assay; cell count Cytotoxicity is related to surfactants
on the nanorod surface.
[141]
CdSe QDs 1.4–2.5 nm 2–200 pM; 24 h Caco-2 МТТ assay; test for cell
culture adhesion
Cytotoxicity is observed at a
concentration of 200 pM because
of the release of Cd from QD cores.
[142]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 8 of 21
Table 1 Results of estimation of nanoparticle toxicity in experimental models of their oral uptake (Continued)
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
Multiwalled carbon
nanotubes modified with
COOH groups
1.4 ± 0.1 nm 5–1000 μg/ml; 24 h Caco-2 MTS assay; LDH assay;
staining with neutral
assay; staining with
trypan blue
Cell death at a nanotube
concentration higher than
100 μg/ml.
[143]
Polystyrene NPs modified
with COOH and NH2 groups
20–40 nm 0.3–12 nm;16 h Caco-2 Transepithelial electrical
resistance measurement
confocal microscopy;
caspase 3 assay; fluorescent
microscopy
The NPs modified with COOH
are more readily absorbed
by cells.
Decreased cell viability
(the negatively charged COOH-modified
NPs are more toxic).
[144]
VO nanotubes Diameter, 15–100 nm 0.1–0.5 mg/ml;
4–24 h
Caco-2 Neutral red assay Cell death caused by the nanotubes. [145]
Polystyrene NPs modified
and not modified with
carboxylic acids
20 and 40 nm 0.3–6.6 nM;
4–16 h
Caco-2 L/D cell assay;
clustering analysis;
apoptosis assay
Decreased cell viability.
Carboxylic acid-functionalized NPs
decrease the cell viability more
quickly and strongly.
[144]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 9 of 21
Table 2 Results of estimation of nanoparticle toxicity in experimental models of their intravenous administration and the consequences of interaction of nanoparticles with cells
of various organs
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
FeОNPs modified and not
modified with polyethylene
oxide triblock copolymer
(PEO-COOH-PEO)
10 nm 1–5 mg/ml; 48 h PC3
C4-2
HUVECs
MTT assay; confocal
microscopy
Decreased viability of all cell types.
NP uptake by cells.
The surface-modified NPs are more
toxic than NPs without shells.
[146]
SiO NPs modified and not
modified with COOH, NH
2
,
and OH
30 and 70 nm 1–6000 μg/ml;
24 h
HUVECs MTS assay; ELISA; LDH
assay; fluorescent
microscopy
The unmodified NPs do not affect cell
viability substantially.
The modified NPs cause death of an
insignificant proportion of cells.
The cell state (static or dynamic) does
not affect cell viability upon interaction
with the NPs but affects internalization
of the NPs (cells in the dynamic state
absorb the NPs more readily).
[147]
CuS nanoplates Length, 59.4 nm;
thickness, 23.8 nm
1–400 μg/ml; 24
and 48 h
HUVECs
RAW 264.7
KB
HeLa
WST-8; confocal microscopy;
scanning electron
microscopy (SEM)
HUVEC viability is considerably more
decreased in the presence of the NPs
at concentrations higher than 100 μg/ml
compared to KB and HeLa cells.
The NPs penetrate only into RAW
264.7 cells.
The NPs do not cause significant
changes in the cytoskeleton of cells of
any line.
[148]
Se NPs modified and not
modified with Ru(II) polypyridyl
100 nm 1–50 μg/ml;
12 and 24 h
HUVECs
HepG2
SW480
PC3
MCF-7
Immunoblotting; confocal
microscopy; MTT assay;
flow cytometry
The modified NPs are 20 to 6 times
more toxic for all cell lines than
the unmodified NPs.
The modified NPs inhibit the
proliferation and migration of HUVECs
and formation of microtubules in them.
The modified NPs are effectively
absorbed by HUVECs and HepG2 cells.
[149]
Ag NPs 35, < 100, and
2000–3500 nm
22, 70, 220, 700,
and 2200 μg/ml;
3.5 h
Human red blood
cells
Hemolytic test The NPs lyse a larger proportion of
red blood cells compared to
micrometer-sized
particles.
Hemolysis is enhanced at NP
concentrations of 220 μg/ml and
higher.
[150]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 10 of 21
Table 2 Results of estimation of nanoparticle toxicity in experimental models of their intravenous administration and the consequences of interaction of nanoparticles with cells
of various organs (Continued)
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
Hydroxyapatite NPs modified
and not modified with
indocyanine green and Gd
3+
50 nm 50–250 mg/ml;
48 h
Mononuclear
blood cells
Mesenchymal
stem cells
MTT assay; hemolytic test;
test for platelet activation
and aggregation; flow
cytometry
The NPs are nontoxic for both stem
cells and mononuclear cells of peripheral
blood, do not cause platelet aggregation
or activation, and do not induce
inflammatory or immune response.
[151]
SiO NPs 100 nm 1–100 μg/ml;
24 and 48 h
HeLa
3T3
MTT assay; trypan blue
test; flow cytometry; LDH
assay; SEM; ROS assay
The NPs are low-toxic, decreasing the
cell survival by more than 20% only at
a concentration of 100 μg/ml.
The NPs do not cause apoptosis, ROS
generation, or serious morphological
changes in cells at concentrations
lower than 100 μg/ml.
[152]
CdTe QDs modified with
mercaptosuccinic acid
4 nm 0.1–100 μg/ml; 24 h HUVECs MTT assay; flow cytometry; ROS assay The QDs are toxic for HUVECs.
The QDs increase the intracellular ROS
level and activate apoptosis.
[153]
CdTe/CdSe/ZnSe QDs modified
with mercaptoundecanoic acid
19.8 ± 5 nm 1.25–60 μg/ml; 1
and 24 h
HepG2, SKBR-3
MCF-7
Alamar blue assay; fluorescent microscopy;
confocal microscopy
The QDs are nontoxic for all cell lines
except HepG2 (for HepG2 cells, they are
toxic at a concentration of 15 μg/ml).
Morphological changes are also observed
only in HepG2 cells.
[154]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 11 of 21
Table 3 Results of estimation of nanoparticle toxicity in experimental models of their inhalation uptake
Type of nanoparticles Sizes Concentration;
incubation time
Cell
line
Method of detection Effects; conclusions Reference
ZnO NPs 288.2 ± 2.4 and 265.7 ±
3.6 nm
4, 10, 25, 50, 100, 250,
500, and 1000 μg/ml;
6 and 24 h
С10 МТS assay; fluorescent
microscopy; ROS assay
Decrease in cell viability after 6
and 24 h of incubation.
Oxidative stress because of
leakage of Zn ions.
[155]
Cu, CuO, ZnO, TiO
2
, Ti, Ag, Co, Ni, NiO, ZrO
2
,
ZrO
2
+Y
2
O
3
, steel, Al
2
О
3
, SnO, WC, and CeO
2
NPs
< 500 nm 1–10,000 μg/ml; 24 h A549
THP-1
MTT assay; neutral red assay The Cu and Zn NPs are the most
toxic.
The Al, Ti, Ce, and Zr NPs are
low-toxic.
The WC NPs are nontoxic.
Toxicity in the NPs is not related
to their shape, diameter, or
surface area.
[156]
CuO NPs 50 nm 1–40 μg/ml; 24 h A549
SAEC
WST-8; SEM; flow cytometry;
confocal microscopy;
immunoblotting; DNA
microarray analysis;
real-time PCR
The NPs are highly toxic for both
cell lines.
The NPs strongly affect the cell
cycle, inhibiting the genes
responsible for proliferation.
The NPs cause apoptosis of A549
and SAEC cells.
[157]
Carbon nanotubes 14, 25.7 ± 1.6, 14.84 ±
0.05, 10.40 ± 0.32, 84.89
± 1.9, and 165.02 ±
4.68 nm
5–50 μg/cm
2
; 24 h THP-1
Met5a
ELISA; trypan blue тест; ROS
assay; flow cytometry
Decreased cell viability and
induction of ROS production.
Intense release of acute phase
inflammatory cytokines (IL-1β,
TNFα, and IL-6) and chemokines
(IL-8) from THP-1 cells.
[158]
CdSe QDs modified with
mercaptoundecanoic acid (MUA),
mercaptopropionic acid (MPA),
aminoundecanoic acid (AUA), or cysteamine
(CA)
3, 5, and 10 nm 0.5, 5, 20, 80, and
160 μg/ml; 22 h
NHBE WST-1; LDH assay; ELISA;
fluorescent microscopy
The positively charged (AUA-
and CA-modified) QDs are more
toxic than the negatively charged
(MUA- and MPA-modified) QDs.
The negatively charged QDs
enhance the expression of
proinflammatory cytokine genes;
the positively charged QDs induce
changes in the genes involved in
mitochondrion functions.
[159]
SiO
2
and Fe
3
O
4
NPs modified and not
modified with sodium oleate; TiO
2
and PLGA
NPs modified with polyethylene oxide (PLGA-
PEO)
PLGA-PEO, 140 nm;
SiO
2
, 25 and 50 nm;
TiO
2
, 21 nm;
Fe
3
O
4
,8nm
0.6–75 μg/cm
2
;24and
48 h
16-HBE
A549
WST-1; flow cytometry;
real-time PCR
The PLGA and TiO
2
NPs have no
considerable effect on 16-HBE or
A549 cell viability.
The modified Fe
3
O
4
NPs are more
toxic than unmodified ones.
The PLGA NPs induce ROS generation
without affecting cell metabolism,
viability, or cytokine production rate.
[160]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 12 of 21
Table 3 Results of estimation of nanoparticle toxicity in experimental models of their inhalation uptake (Continued)
Type of nanoparticles Sizes Concentration;
incubation time
Cell
line
Method of detection Effects; conclusions Reference
CdSe/ZnS QDs modified with COOH or NH
2
groups (COOH-QDs and NH
2
-QDs,
respectively)
4–10 nm 2.5, 5, 7.5, 10, 15, and
20 nM; 1–3 cell cycles
BEAS-
2B
HFF-1
TK6
Flow cytometry; transmission
electron microscopy
(TEM); ELISA; ROS assay; calculation
of cell population doubling
time; fluorescent microscopy
The rate of QD uptake is considerably
higher in BEAS-2B and TK6 cells.
The COOH-QDs are more readily absorbed
by cells.
TK6 and HFF-1 cells are more sensitive to
the QDs (a high toxicity is observed at
concentrations higher than 15 nM) than
BEAS-2B cells (a high toxicity is observed at
concentrations higher than 20 nM). Minor
changes in the ROS level are observed only
in HFF-1 cells in the presence of the
COOH-QDs and in TK6 cells in the presence
of the NH
2
-QDs.
[161]
InP/ZnS and CdSe/ZnS QDs InP/ZnS,
11.3 ± 0.6 nm;
CdSe/ZnS,
13.4 ± 0.7 nm
1, 10, and
100 pM and 1
and 5 nM; 24 and 48 h
A549
SHSY5Y
WST-8; LDH assay; glutathione
level measurement; analysis of
mRNA expression level;
TUNEL test
The CdSe/ZnS QDs damage the cell
membrane, enhance the expression of
detoxification enzyme genes, increase
the antioxidant level, cause DNA damage,
and disturb Ca
2+
homeostasis in cells.
The InP/ZnS QDs are less toxic.
[162]
CeO
2
NPs 15, 25, 30, and
45 nm
5, 10, 20, and
40 g/ml
BEAS-
2B
MTT assay; glutathione level
measurement; MTT assay; ROS
assay; caspase 3 assay; fluorescent
microscopy
Cell death mediated by ROS generation.
The NPs are absorbed by cells and localized
in the perinuclear space.
[55]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 13 of 21
Table 4 Results of estimation of nanoparticle toxicity in experimental models of their transdermal uptake
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
Ag NPs modified with digallic
acid (DA-Ag) and not modified
DA–Ag, 13, 33, and
46 nm;Ag, 10–65 nm
1–10 μg/ml; 24 h 291.03C
RAW 264.7
Neutral red assay; flow cytometry;
TEM; [
3
H]thymidine staining of DNA;
estimation of mitochondrion activity
(JC-1 test)
The Ag NPs decrease the proliferation
rate of both cell lines. The NPs enhance
ROS generation in RAW 264.7 cells. RAW
264.7 cells absorb the 10- to 65-nm Ag
and 33 and 46-nm, DA-Ag NPs, whereas
291.03C cells absorb only the 13-nm
DA–Ag NPs. The Ag NPs suppress the
production of TNFαby RAW 264.7 cells
and enhance its production by 291.03C
cells. The 33- and 46-nm DA-Ag NPs are
the least toxic.
[163]
Si NPs modified with Al
2
O
3
(Al
2
O
3
-Si) and Na (Na-Si)
Al
2
O
3
-Si, 21 nm;
Na-Si, 30 nm
40–800 μg/ml; 72 h;
7 days
3T3-L1
WI-38
WST-1; LDH assay; glutathione
level measurement
The Al
2
O
3
-Si NPs are nontoxic for 3T3-L1
cells and slightly toxic for WI-38 cells
(a small decrease in viability at an NP
concentration of 250 μg/ml). The Na-Si
NPs are toxic for both 3 T3-L1 and WI-38
cells.
[164]
ZnO NPs modified with
NH
2
groups
20 nm 1–50 μg/ml;
0.5–24 h
HaCaT
SCCE02
MTT assay; immunoblotting;
ELISA; TEM; real-time PCR;
ROS assay; fluorescent microscopy
Decreased viability of both cell lines at NP
concentrations of 10 μg/ml and higher.
Induction of oxidative stress through
activation of MAP kinase signal pathways
(ERK, JNК, and p38). Enhanced expression
of Egr-1 and, as a consequence, TNFα.
[165]
Multiwalled carbon
nanotubes (MWCNTs)
Diameter, 12 nm 100 μg/ml SZ95
IHK
MTS assay; LDH assay; transepithelial
electrical resistance measurement;
[
3
H]thymidine staining of DNA; TEM
MWCNTs are toxic only for IHK cells.
The TEER is unchanged, which indicates
that MWCNTs do not affect the tight
junctions of epidermal cells.
[166]
ZnO and TiO
2
NPs 268.1 ± 11.2 and
414.9 ± 4.5 nm
0.5–10 μg/ml;
24, 48, and 72 h;
3 months
NCTC2544 MTS assay; scanning electron
microscopy; ROS assay; flow cytometry
Decrease in viability upon incubation in
the presence of the ZnO NPs at
concentrations higher than 15 μg/ml for
24–72 h. Prolonged incubation causes
changes in cell morphology and affects
the cell cycle.
The TiO
2
NPs are nontoxic.
The NP toxicity is related to the release
of metal ions inducing oxidative stress.
[167]
CdSe/CdS NPs modified
with polyethylene glycol
39–40 nm 0.3125–10 nM;
24 and 48 h
NHEK Confocal microscopy; TEM; flow
cytometry; atomic emission
spectroscopy
Decreased viability at NP concentrations
higher than 1.25 nM. Enhanced IL-8 and
IL-6 production.
[168]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 14 of 21
Table 4 Results of estimation of nanoparticle toxicity in experimental models of their transdermal uptake (Continued)
Type of nanoparticles Sizes Concentration;
incubation time
Cell line Method of detection Effects; conclusions Reference
NaYF
4
NPs modified with
different compounds
94–550 nm 62.5 and
125 μg/ml; 24 h
HaCaT
Human skin
fibroblasts
MTT assay; confocal microscopy;
fluorescent microscopy
The NPs coated with polyethyleneimine
(PEI), poly(lactide-co glycolide) (PLG),
and PLG + dextran sulfate are the most
toxic (52, 61, and 72% viable cells,
respectively).
The NPs are nontoxic for fibroblasts.
Hydrophilic NPs are the least toxic and are
the most readily absorbed by the cells.
[169]
TiO
2
NPs 124.9 nm 0.008–80 μg/ml;
6, 24, and 48 h
A431 MTT assay; Bradford protein
assay; flow cytometry;
glutathione level measurement;
lipid peroxidase assay; DNA
comet assay; ROS assay
A slight decrease in cell viability after 48 h
of treatment.
DNA damage with ROSs and micronucleus
formation.
[170]
Polyamidoamine (PAMAM)
dendrimers
4.5, 5.4, and
6.7 nm
0.01–21 μM;
24 h; 8 days
HaCaT
SW480
MTT, clonogenic, Alamar Blue,
and neutral red assays
The toxicity of the dendrimers linearly
increases with increasing both their zeta
potential and their size.
[171]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 15 of 21
shown to be toxic for mice, causing weight loss, decrease
in the hematocrit, and reduction of the red blood cell
count.
Targeted drug delivery is one of the most important
applications of NPs. In this case, it is also paramount to
know their toxic properties, because the positive effect
of their use should prevail over the negative one. Kwon
et al. [116] have developed antioxidant NPs from the
polymeric prodrug of vanillin. Their study has shown
that the NPs have no toxic effect on the body, specific-
ally the liver, at doses lower than 2.5 mg/kg. Similar re-
sults have been obtained for gelatin NPs modified with
polyethylene glycol, which are planned to be used for
targeted delivery of ibuprofen sodium salt [117]. The
NPs have proved to be nontoxic at the dose that is ne-
cessary for effective drug delivery (1 mg/kg), which has
been confirmed by measuring the inflammatory cytokine
levels in the animals studied, as well as histological
analysis of their organs.
Quantum dots are among the NPs that are most
promising for medical applications (Fig. 2). However,
they are potentially hazardous for human health, because
they exhibit various toxic effects in both in vitro and in
vivo experiments [118–122].
Toxic effects of QDs in vivo are usually studied in ex-
periments on mice and rats [123]. A study on the
toxicity of cadmium-based QDs for mice showed that
QDs were distributed throughout the body as soon as
15 min after injection to the caudal vein, after which
they accumulated in the liver, kidneys, spleen, red bone
marrow, and lymph nodes. Two years after the injection,
fluorescence was mainly retained in lymph nodes; in
other organs, no QDs were detected [124]. It should be
also noted that the fluorescence spectrum was shifted to
the blue spectral region because of the destruction of
the QD shell and changes in the shape, size, and surface
charge of the QDs. This, however, occurred rather
slowly, because the QDs were found to be nontoxic after
their injection at the doses at which pure cadmium ions
would have had a lethal effect. Similar results were ob-
tained by Yang et al. [125]. Zhang et al. [95] showed that
CdTe QDs predominantly accumulated in the liver, de-
creasing the amount of antioxidants in it and inducing
oxidative stress in liver cells.
Cadmium and tellurium ions tend to accumulate in
various organs and tissues upon degradation and decay
of the cores of CdTe/ZnS QDs. Experiments on mice
have shown that cadmium predominantly accumulates
in the liver, kidneys, and spleen, whereas tellurium
accumulates almost exclusively in the kidneys [126].
Ballou et al. [127] found that cadmium-containing QDs
coated with polymer shells of polyacrylic acid or
different derivatives of polyethylene glycol had no lethal
effect on experimental mice and remained fluorescent
for 4 months. СdSe/ZnS NPs also had no detectable
pathological effect on mice [128]; however, the absence
of distinct signs of pathology still does not mean that
theQDsareabsolutelynontoxic.
Hu et al. [129] found that lead-containing QDs had no
toxic effect on mice for 4 weeks; however, this was most
probably because the QDs studied were coated with a
polyethylene glycol shell.
Since heavy metals contained in QDs are a factor of
their toxicity, several research groups suggested that
heavy-metal-free NPs be synthesized. For example, Pons
et al. [130] synthesized CuInS2/ZnS QDs fluorescing in
the near-infrared spectral region (at a wavelength of
about 800 nm) and supposed that this composition
would make the QDs nontoxic for experimental animals.
Comparison of the effects of CuInS
2
/ZnS and CdTeSe/
CdZnS QDs on regional lymph nodes in mice showed
that the lymph nodes were only slightly, if at all, en-
larged upon injection of the QDs not containing heavy
metals, whereas injection of the CdTeSe/CdZnS QDs in-
duced a distinct immune response in them [130]. QDs
in which silicon was substituted for heavy metals also
had no toxic effect on mice [131].
Even QDs containing heavy metals are often found to
be nontoxic. One of the possible explanations is that
QDs are coated with the protein crown upon entering
the living body; this crown shields their surface and pro-
tects cells against damage [132]. Usually, the proteins
that are included in the NP molecular corona are major
serum proteins, such as albumin, immunoglobulin G
(IgG), fibrinogen, and apolipoproteins [133]. Molecular
corona also can influence on the interaction of NPs with
Fig. 2 The possible reasons why quantum dots may be nontoxic in
animal models. (1) The shell prevents the leakage of heavy metals into
the body [129,135]. (2) Quantum dots are localized in the liver and
subsequently eliminated from the body [135,173]. (3) The protein crown
around quantum dots protects the body from heavy metals [132,174]
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 16 of 21
cells. Zyuzin et al. have demonstrated that, in human
endothelial cells, the NP protein corona decreases the
NP nonspecific binding to the cell membrane, increases
the residence time of NP in early endosomes, and re-
duces the amount of internalized NPs [134].
However, even in the absence of direct signs of intoxi-
cation in experimental animals, it remains unclear
whether the use of QDs in medicine is safe for humans.
In some cases, the QD toxicity was not detected in mice
because the NPs were neutralized by the liver and accu-
mulated in it [135]; in other cases, QDs coated with
phospholipid micelles exhibited reduced toxicity owing
to the shell [129]. Despite the extensive in vivo studies
on QD toxicity, their use in biomedicine remains an
open question. One of the main reasons is that all the
delayed effects of QDs cannot be monitored in experi-
mental animals, because their lifespan is as short as a
few years, which is insufficient for complete elimination
or degradation of NPs.
Conclusions
The potential toxicity of NPs is the main problem of
their use in medicine. Therefore, not only positive re-
sults of the use of NPs, but also the possible unpre-
dictable negative consequences of their action on the
human body, should be scrutinized. The toxicity of
NPs is related to their distribution in the bloodstream
and lymph stream and their capacities for penetrating
into almost all cells, tissues, and organs and interact-
ing with various macromolecules and altering their
structure, thereby interfering with intracellular pro-
cesses and the functioning of whole organs. The NP
toxicity strongly depends on their physical and chem-
ical properties, such as the shape, size, electric charge,
and chemical compositions of the core and shell.
Many types of NPs are not recognized by the protect-
ive systems of cells and the body, which decreases the
rate of their degradation and may lead to considerable
accumulation of NPs in organs and tissues, even to
highly toxic and lethal concentrations. However, a
number of approaches to designing NPs with a de-
creased toxicity compared to the traditional NPs are
already available. Advanced methods for studying the
NP toxicity make it possible to analyze different path-
ways and mechanisms of toxicity at the molecular
level, as well as reliably predict the possible negative
effect at the body level.
Thus, it is obvious that designing NPs that have small
or no negative effects is impossible unless all qualitative
and quantitative physical and chemical properties of NPs
are systematically taken into consideration and a rele-
vant experimental model for estimating their influence
on biological systems is available.
Abbreviations
FDA: Food and Drug Administration; IL-1β: Interleukin-1-beta; MRT: Magnetic
resonance tomography; NP: Nanoparticle; QD: Quantum dot; ROS: Reactive
oxygen species; SEM: Scanning electron microscopy; TEM: Transmission
electron microscopy; TNFα: Tumor necrosis factor alpha
Acknowledgements
The authors thank Vladimir Ushakov for proofreading the manuscript.
Funding
This study was supported by the Ministry of Education and Science of the
Russian Federation, State Contract no. 16.1034.2017/ ПЧ.
Availability of data and materials
The datasets generated during and/or analyzed during the current study are
available from the corresponding authors on reasonable request.
Authors’contributions
IN and AS defined the topic of review and selected the key publications. All
authors wrote different parts of the manuscript. All authors commented on
the manuscript. All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
Laboratoire de Recherche en Nanosciences, LRN-EA4682, Université de
Reims Champagne-Ardenne, 51100 Reims, France.
2
Laboratory of
Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow
Engineering Physics Institute), 31 Kashirskoe shosse, Moscow, Russian
Federation115521.
3
Department of Clinical Immunology and Allergology, I.M.
Sechenov First Moscow State Medical University, Moscow, Russian
Federation119992.
Received: 10 January 2018 Accepted: 25 January 2018
References
1. Iqbal MA, Md S, Sahni JK, Baboota S, Dang S, Ali J (2012) Nanostructured
lipid carriers system: recent advances in drug delivery. J Drug Target 20(10):
813–830
2. Liechty WB, Kryscio DR, Slaughter BV, Peppas NA (2010) Polymers for drug
delivery systems. Annu Rev Chem Biomol Eng 1(1):149–173
3. Peckys DB, de Jonge N (2011) Visualizing gold nanoparticle uptake in live
cells with liquid scanning transmission electron microscopy. Nano Lett
11(4):1733–1738
4. Phillips E, Penate-Medina O, Zanzonico PB, Carvajal RD, Mohan P, Ye Y et al
(2014) Clinical translation of an ultrasmall inorganic optical-PET imaging
nanoparticle probe. Sci Transl Med 6(260):260ra149
5. Lucky SS, Soo KC, Zhang Y (2015) Nanoparticles in photodynamic therapy.
Chem Rev 115(4):1990–2042
6. Ma L, Zou X, Chen W (2014) A new X-ray activated nanoparticle
photosensitizer for cancer treatment. J Biomed Nanotechnol 10(8):1501–1508
7. FDA approves Celgene drug Abraxane for late-stage pancreatic cancer | CTV
News n.d.; https://www.ctvnews.ca/health/fda-approves-abraxane-for-late-
stage-pancreatic-cancer-1.1444152. Accessed 9 Jan 2018.
8. FDA Approval for Doxorubicin HCl Liposome—National Cancer Institute n.
d.; https://www.cancer.gov/about-cancer/treatment/drugs/fda-doxorubicin-
HCL-liposome. Accessed 9 Jan 2018
9. Gastromark—FDA prescribing information, side effects and uses n.d.;
https://www.drugs.com/pro/gastromark.html. Accessed 9 Jan 2018
10. Connor EE, Mwamuka J, Gole A, Murphy CJ, Wyatt MD (2005) Gold
nanoparticles are taken up by human cells but do not cause acute
cytotoxicity. Small 1(3):325–327
11. Davis ME, Chen Z (Georgia), Shin DM (2008) Nanoparticle therapeutics: an
emerging treatment modality for cancer. Nat Rev Drug Discov 7(9):771–782
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 17 of 21
12. Bartlett DW, Su H, Hildebrandt IJ, Weber WA, Davis ME (2007) Impact of
tumor-specific targeting on the biodistribution and efficacy of siRNA
nanoparticles measured by multimodality in vivo imaging. Proc Natl Acad
Sci U S A 104(39):15549–15554
13. Eby DM, Luckarift HR, Johnson GR (2009) Hybrid antimicrobial enzyme and
silver nanoparticle coatings for medical instruments. ACS Appl Mater
Interfaces 1(7):1553–1560
14. De Jong WH, Borm PJA (2008) Drug delivery and nanoparticles: applications
and hazards. Int J Nanomedicine 3(2):133–149
15. Altınoğlu Eİ, Adair JH (2010) Near infrared imaging with nanoparticles. Wiley
Interdiscip Rev Nanomed Nanobiotechnol 2(5):461–477
16. Medintz IL, Uyeda HT, Goldman ER, Mattoussi H (2005) Quantum dot
bioconjugates for imaging, labelling and sensing. Nat Mater 4:435–446
17. Murphy CJ (2002) Optical sensing with quantum dots. Anal Chem 74(19):
520A–526A
18. Zhang J, Campbell RE, Ting AY, Tsien RY (2002) Creating new fluorescent
probes for cell biology. Nat Rev Mol Cell Biol 3(12):906–918
19. Baptista PV, Doria G, Quaresma P, Cavadas M, Neves CS, Gomes I et al
(2011) Nanoparticles in molecular diagnostics. Prog Mol Biol Transl Sci
104:427–488
20. Baetke SC, Lammers T, Kiessling F (2015) Applications of nanoparticles for
diagnosis and therapy of cancer. Br J Radiol 88(1054):20150207
21. Mornet S, Vasseur S, Grasset F, Duguet E (2004) Magnetic nanoparticle
design for medical diagnosis and therapy. J Mater Chem 14(14):2161
22. Kang S, Herzberg M, Rodrigues DF, Elimelech M. Antibacterial effects of
carbon nanotubes: size does matter! Langmuir 2008;24(13):6409–13
23. Muguruma H, Matsui Y, Shibayama Y (2007) Carbon nanotube–plasma
polymer-based amperometric biosensors: enzyme-friendly platform for
ultrasensitive glucose detection. Jpn J Appl Phys 46(9A):6078–6082
24. Clendenin J, Kim J-W, Tung S. An aligned carbon nanotube biosensor for
DNA detection. 2007 2nd IEEE Int. Conf. Nano/Micro Eng. Mol. Syst., IEEE;
2007, p. 1028–1033
25. Timur S, Anik U, Odaci D, Gorton L (2007) Development of a microbial
biosensor based on carbon nanotube (CNT) modified electrodes.
Electrochem Commun 9(7):1810–1815
26. Kokura S, Handa O, Takagi T, Ishikawa T, Naito Y, Yoshikawa T (2010) Silver
nanoparticles as a safe preservative for use in cosmetics. Nanomed
Nanotechnol Biol Med. 6(4):570–574
27. Dukhin SS, Labib ME (2013) Convective diffusion of nanoparticles from
the epithelial barrier toward regional lymph nodes. Adv Colloid Interf Sci
199–200:23–43
28. Oberdörster G, Maynard A, Donaldson K, Castranova V, Fitzpatrick J, Ausman
K et al (2005) Principles for characterizing the potential human health
effects from exposure to nanomaterials: elements of a screening strategy.
Part Fibre Toxicol. 2(1):8
29. Holsapple MP, Farland WH, Landry TD, Monteiro-Riviere NA, Carter JM,
Walker NJ et al (2005) Research strategies for safety evaluation of
nanomaterials, part II: toxicological and safety evaluation of nanomaterials,
current challenges and data needs. Toxicol Sci 88(1):12–17
30. Hoet PH, Brüske-Hohlfeld I, Salata OV (2004) Nanoparticles—known and
unknown health risks. J Nanobiotechnology. 2(1):12
31. Ryman-Rasmussen JP, Riviere JE, Monteiro-Riviere NA (2006) Penetration of
intact skin by quantum dots with diverse physicochemical properties.
Toxicol Sci 91(1):159–165
32. Schneider M, Stracke F, Hansen S, Schaefer UF (2009) Nanoparticles and
their interactions with the dermal barrier. Dermatoendocrinol
1(4):197–206
33. Tinkle SS, Antonini JM, Rich BA, Roberts JR, Salmen R, DePree K et al (2003)
Skin as a route of exposure and sensitization in chronic beryllium disease.
Environ Health Perspect 111(9):1202–1208
34. Singh R, Lillard JW Jr (2009) Nanoparticle-based targeted drug delivery. Exp
Mol Pathol 86(3):215–223
35. Radomski A, Jurasz P, Alonso-Escolano D, Drews M, Morandi M, Malinski T et
al (2005) Nanoparticle-induced platelet aggregation and vascular
thrombosis. Br J Pharmacol 146(6):882–893
36. Madl AK, Plummer LE, Carosino C, Pinkerton KE (2014) Nanoparticles,
lung injury, and the role of oxidant stress. Annu Rev Physiol
76(1):447–465
37. Lucchini RG, Dorman DC, Elder A, Veronesi B (2012) Neurological impacts
from inhalation of pollutants and the nose-brain connection.
Neurotoxicology 33(4):838–841
38. Zhu M-T, Feng W-Y, Wang Y, Wang B, Wang M, Ouyang H et al (2009)
Particokinetics and extrapulmonary translocation of intratracheally instilled
ferric oxide nanoparticles in rats and the potential health risk assessment.
Toxicol Sci 107(2):342–351
39. Barua S, Mitragotri S (2014) Challenges associated with penetration of
nanoparticles across cell and tissue barriers: a review of current status and
future prospects. Nano Today 9(2):223–243
40. Nguyen KC, Rippstein P, Tayabali AF, Willmore WG (2015) Mitochondrial
toxicity of cadmium telluride quantum dot nanoparticles in mammalian
hepatocytes. Toxicol Sci 146(1):31–42
41. Singh BR, Singh BN, Khan W, Singh HB, Naqvi AH (2012) ROS-mediated
apoptotic cell death in prostate cancer LNCaP cells induced by
biosurfactant stabilized CdS quantum dots. Biomaterials 33(23):5753–5767
42. Ambrosone A, Mattera L, Marchesano V, Quarta A, Susha AS, Tino A et al (2012)
Mechanisms underlying toxicity induced by CdTe quantum dots determined
in an invertebrate model organism. Biomaterials 33(7):1991–2000
43. Ruenraroengsak P, Novak P, Berhanu D, Thorley AJ, Valsami-Jones E, Gorelik J
et al (2012) Respiratory epithelial cytotoxicity and membrane damage (holes)
caused by amine-modified nanoparticles. Nanotoxicology 6(1):94–108
44. Wang T, Bai J, Jiang X, Nienhaus GU (2012) Cellular uptake of nanoparticles
by membrane penetration: a study combining confocal microscopy with
FTIR spectroelectrochemistry. ACS Nano 6(2):1251–1259
45. Mao Z, Xu B, Ji X, Zhou K, Zhang X, Chen M et al (2015) Titanium dioxide
nanoparticles alter cellular morphology via disturbing the microtubule
dynamics. Nano 7(18):8466–8475
46. Wu X, Tan Y, Mao H, Zhang M (2010) Toxic effects of iron oxide
nanoparticles on human umbilical vein endothelial cells. Int J
Nanomedicine 5:385–399
47. Walkey CD, Olsen JB, Guo H, Emili A, Chan WCW (2012) Nanoparticle size
and surface chemistry determine serum protein adsorption and
macrophage uptake. J Am Chem Soc 134(4):2139–2147
48. Kostura L, Kraitchman DL, Mackay AM, Pittenger MF, Bulte JWM (2004)
Feridex labeling of mesenchymal stem cells inhibits chondrogenesis but
not adipogenesis or osteogenesis. NMR Biomed 17(7):513–517
49. Chen Y-C, Hsiao J-K, Liu H-M, Lai I-Y, Yao M, Hsu S-C et al (2010) The
inhibitory effect of superparamagnetic iron oxide nanoparticle
(Ferucarbotran) on osteogenic differentiation and its signaling mechanism
in human mesenchymal stem cells. Toxicol Appl Pharmacol 245(2):272–279
50. Kedziorek DA, Muja N, Walczak P, Ruiz-Cabello J, Gilad AA, Jie CC et al
(2010) Gene expression profiling reveals early cellular responses to
intracellular magnetic labeling with superparamagnetic iron oxide
nanoparticles. Magn Reson Med 63(4):1031–1043
51. Puppi J, Mitry RR, Modo M, Dhawan A, Raja K, Hughes RD (2011) Use of a
clinically approved iron oxide MRI contrast agent to label human
hepatocytes. Cell Transplant 20(6):963–976
52. Wang L, Hu C, Shao L (2017) The antimicrobial activity of nanoparticles: present
situation and prospects for the future. Int J Nanomedicine 12:1227–1249
53. Poirier M, Simard J-C, Antoine F, Girard D (2014) Interaction between silver
nanoparticles of 20 nm (AgNP20 ) and human neutrophils: induction of
apoptosis and inhibition of de novo protein synthesis by AgNP20
aggregates. J Appl Toxicol 34(4):404–412
54. Choi S-J, Oh J-M, Choy J-H (2009) Toxicological effects of inorganic
nanoparticles on human lung cancer A549 cells. J Inorg Biochem 103(3):
463–471
55. Park E-J, Park K (2009) Oxidative stress and pro-inflammatory responses
induced by silica nanoparticles in vivo and in vitro. Toxicol Lett 184(1):18–25
56. Lévy M, Lagarde F, Maraloiu V-A, Blanchin M-G, Gendron F, Wilhelm C et al
(2010) Degradability of superparamagnetic nanoparticles in a model of
intracellular environment: follow-up of magnetic, structural and chemical
properties. Nanotechnology 21(39):395103
57. Liu J, Katahara J, Li G, Coe-Sullivan S, Hurt RH (2012) Degradation products
from consumer nanocomposites: a case study on quantum dot lighting.
Environ Sci Technol. 46(6):3220–3227
58. Oh E, Liu R, Nel A, Gemill KB, Bilal M, Cohen Y et al (2016) Meta-analysis of
cellular toxicity for cadmium-containing quantum dots. Nat Nanotechnol
11(5):479–486
59. Huo S, Jin S, Ma X, Xue X, Yang K, Kumar A et al (2014) Ultrasmall gold
nanoparticles as carriers for nucleus-based gene therapy due to size-
dependent nuclear entry. ACS Nano 8(6):5852–5862
60. Pan Y, Neuss S, Leifert A, Fischler M, Wen F, Simon U et al (2007) Size-
dependent cytotoxicity of gold nanoparticles. Small 3(11):1941–1949
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 18 of 21
61. SoenenSJ,Rivera-GilP,MontenegroJ-M,ParakWJ,DeSmedtSC,BraeckmansK
(2011) Cellular toxicity of inorganic nanoparticles: common aspects and
guidelines for improved nanotoxicity evaluation. Nano Today 6(5):446–465
62. Schmid G (2008) The relevance of shape and size of Au55 clusters. Chem
Soc Rev 37(9):1909–1930
63. Zhang S, Gao H, Bao G (2015) Physical principles of nanoparticle cellular
endocytosis. ACS Nano 9(9):8655–8671
64. Nel A, Xia T, Mädler L, Li N (2006) Toxic potential of materials at the
nanolevel. Science 311(5761):622–627
65. De Jong WH, Hagens WI, Krystek P, Burger MC, Sips AJAM, Geertsma RE
(2008) Particle size-dependent organ distribution of gold nanoparticles after
intravenous administration. Biomaterials 29(12):1912–1919
66. Talamini L, Violatto MB, Cai Q, Monopoli MP, Kantner K, KrpetićŽet al
(2017) Influence of size and shape on the anatomical distribution of
endotoxin-free gold nanoparticles. ACS Nano 11(6):5519–5529
67. Zhao Y, Sun X, Zhang G, Trewyn BG, Slowing II, Lin VS-Y (2011) Interaction
of mesoporous silica nanoparticles with human red blood cell membranes:
size and surface effects. ACS Nano 5(2):1366–1375
68. Kong B, Seog JH, Graham LM, Lee SB (2011) Experimental considerations on
the cytotoxicity of nanoparticles. Nanomedicine (Lond) 6(5):929–941
69. Ispas C, Andreescu D, Patel A, Goia DV, Andreescu S, Wallace KN (2009)
Toxicity and developmental defects of different sizes and shape nickel
nanoparticles in zebrafish. Environ Sci Technol. 43(16):6349–6356
70. Favi PM, Gao M, Johana Sepúlveda Arango L, Ospina SP, Morales M, Pavon JJ
et al (2015) Shape and surface effects on the cytotoxicity of nanoparticles: gold
nanospheres versus gold nanostars. J Biomed Mater Res A 103(11):3449–3462
71. Hamilton RF, Wu N, Porter D, Buford M, Wolfarth M, Holian A (2009) Particle
length-dependent titanium dioxide nanomaterials toxicity and bioactivity.
Part Fibre Toxicol. 6(1):35
72. Champion JA, Mitragotri S (2006) Role of target geometry in phagocytosis.
Proc Natl Acad Sci U S A 103(13):4930–4934
73. Park KH, Chhowalla M, Iqbal Z, Sesti F (2003) Single-walled carbon
nanotubes are a new class of ion channel blockers. J Biol Chem 278(50):
50212–50216
74. Zhao X, Ng S, Heng BC, Guo J, Ma L, Tan TTY et al (2013) Cytotoxicity of
hydroxyapatite nanoparticles is shape and cell dependent. Arch Toxicol
87(6):1037–1052
75. Hu W, Peng C, Lv M, Li X, Zhang Y, Chen N et al (2011) Protein corona-
mediated mitigation of cytotoxicity of graphene oxide. ACS Nano 5(5):
3693–3700
76. Yang H, Liu C, Yang D, Zhang H, Xi Z (2009) Comparative study of
cytotoxicity, oxidative stress and genotoxicity induced by four typical
nanomaterials: the role of particle size, shape and composition. J Appl
Toxicol 29(1):69–78
77. Soenen SJ, Parak WJ, Rejman J, Manshian B (2015) (Intra)cellular stability of
inorganic nanoparticles: effects on cytotoxicity, particle functionality, and
biomedical applications. Chem Rev 115(5):2109–2135
78. Gurr J-R, Wang ASS, Chen C-H, Jan K-Y (2005) Ultrafine titanium dioxide
particles in the absence of photoactivation can induce oxidative damage to
human bronchial epithelial cells. Toxicology 213(1–2):66–73
79. Zhang H, Gilbert B, Huang F, Banfield JF (2003) Water-driven structure
transformation in nanoparticles at room temperature. Nature 424(6952):
1025–1029
80. Schaeublin NM, Braydich-Stolle LK, Schrand AM, Miller JM, Hutchison J,
Schlager JJ et al (2011) Surface charge of gold nanoparticles mediates
mechanism of toxicity. Nano 3(2):410–420
81. El Badawy AM, Silva RG, Morris B, Scheckel KG, Suidan MT, Tolaymat TM
(2011) Surface charge-dependent toxicity of silver nanoparticles. Environ Sci
Technol 45(1):283–287
82. Zhang Y, Kohler N, Zhang M (2002) Surface modification of
superparamagnetic magnetite nanoparticles and their intracellular uptake.
Biomaterials 23(7):1553–1561
83. Cheyne RW, Smith TA, Trembleau L, McLaughlin AC (2011) Synthesis and
characterisation of biologically compatible TiO2 nanoparticles. Nanoscale
Res Lett 6(1):423
84. Kango S, Kalia S, Celli A, Njuguna J, Habibi Y, Kumar R (2013) Surface
modification of inorganic nanoparticles for development of organic–
inorganic nanocomposites—a review. Prog Polym Sci 38(8):1232–1261
85. Liu Y, Li W, Lao F, Liu Y, Wang L, Bai R et al (2011) Intracellular dynamics of
cationic and anionic polystyrene nanoparticles without direct interaction
with mitotic spindle and chromosomes. Biomaterials 32(32):8291–8303
86. Hühn D, Kantner K, Geidel C, Brandholt S, De Cock I, Soenen SJH et al
(2013) Polymer-coated nanoparticles interacting with proteins and cells:
focusing on the sign of the net charge. ACS Nano 7(4):3253–3263
87. Alexis F, Pridgen E, Molnar LK, Farokhzad OC (2008) Factors affecting the
clearance and biodistribution of polymeric nanoparticles. Mol Pharm 5(4):
505–515
88. Lundqvist M, Stigler J, Elia G, Lynch I, Cedervall T, Dawson KA (2008)
Nanoparticle size and surface properties determine the protein corona with
possible implications for biological impacts. Proc Natl Acad Sci U S A
105(38):14265–14270
89. Gunawan C, Lim M, Marquis CP, Amal R (2014) Nanoparticle–protein corona
complexes govern the biological fates and functions of nanoparticles.
J Mater Chem B 2(15):2060
90. Sukhanova A, Poly S, Shemetov A, Nabiev IR. Quantum dots induce charge-
specific amyloid-like fibrillation of insulin at physiological conditions. In:
Choi SH, Choy J-H, Lee U, Varadan VK, editors. vol. 8548, International
Society for Optics and Photonics; 2012, p. 85485F
91. Linse S, Cabaleiro-Lago C, Xue W-F, Lynch I, Lindman S, Thulin E et al (2007)
Nucleation of protein fibrillation by nanoparticles. Proc Natl Acad Sci U S A
104(21):8691–8696
92. Xu P, Van Kirk EA, Zhan Y, Murdoch WJ, Radosz M, Shen Y (2007) Targeted
charge-reversal nanoparticles for nuclear drug delivery. Angew Chemie Int
Ed 46(26):4999–5002
93. Asati A, Santra S, Kaittanis C, Perez JM (2010) Surface-charge-dependent cell
localization and cytotoxicity of cerium oxide nanoparticles. ACS Nano 4(9):
5321–5331
94. Arami H, Khandhar A, Liggitt D, Krishnan KM (2015) In vivo delivery,
pharmacokinetics, biodistribution and toxicity of iron oxide nanoparticles.
Chem Soc Rev 44(23):8576–8607
95. Zhang T, Hu Y, Tang M, Kong L, Ying J, Wu T et al (2015) Liver toxicity of
cadmium telluride quantum dots (CdTe QDs) due to oxidative stress in vitro
and in vivo. Int J Mol Sci 16(10):23279–23299
96. Xia T, Li N, Nel AE (2009) Potential health impact of nanoparticles. Annu Rev
Public Health 30(1):137–150
97. Peng L, He M, Chen B, Wu Q, Zhang Z, Pang D et al (2013) Cellular uptake,
elimination and toxicity of CdSe/ZnS quantum dots in HepG2 cells.
Biomaterials 34(37):9545–9558
98. Cho J, Kushiro K, Teramura Y, Takai M (2014) Lectin-tagged fluorescent
polymeric nanoparticles for targeting of sialic acid on living cells.
Biomacromolecules 15(6):2012–2018
99. Gregory AE, Titball R, Williamson D (2013) Vaccine delivery using
nanoparticles. Front Cell Infect Microbiol 3:13
100. Guo G, Liu W, Liang J, He Z, Xu H, Yang X (2007) Probing the
cytotoxicity of CdSe quantum dots with surface modification. Mater
Lett 61(8–9):1641–1644
101. Hardman R (2006) A toxicologic review of quantum dots: toxicity depends
on physicochemical and environmental factors. Environ Health Perspect
114(2):165–172
102. Huang J, Wang L, Lin R, Wang AY, Yang L, Kuang M et al (2013) Casein-
coated iron oxide nanoparticles for high MRI contrast enhancement and
efficient cell targeting. ACS Appl Mater Interfaces 5(11):4632–4639
103. Donaldson K, Stone V, Tran CL, Kreyling W, Borm PJA (2004)
Nanotoxicology. Occup Environ Med 61(9):727–728
104. Bouwmeester H, Poortman J, Peters RJ, Wijma E, Kramer E, Makama S et al
(2011) Characterization of translocation of silver nanoparticles and effects
on whole-genome gene expression using an in vitro intestinal epithelium
coculture model. ACS Nano 5(5):4091–4103
105. Brandenberger C, Rothen-Rutishauser B, Mühlfeld C, Schmid O, Ferron GA,
Maier KL et al (2010) Effects and uptake of gold nanoparticles deposited at
the air-liquid interface of a human epithelial airway model. Toxicol Appl
Pharmacol 242(1):56–65
106. Sriram G, Bigliardi PL, Bigliardi-Qi M (2015) Fibroblast heterogeneity and its
implications for engineering organotypic skin models in vitro. Eur J Cell Biol
94(11):483–512
107. Abbott A (2003) Cell culture: biology’s new dimension. Nature 424(6951):
870–872
108. Lee J, Cuddihy MJ, Kotov NA (2008) Three-dimensional cell culture matrices:
state of the art. Tissue Eng Part B Rev 14(1):61–86
109. Kuhn SJ, Hallahan DE, Giorgio TD (2006) Characterization of
superparamagnetic nanoparticle interactions with extracellular matrix in an
in vitro system. Ann Biomed Eng 34(1):51–58
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 19 of 21
110. Li XJ, Valadez AV, Zuo P, Nie Z (2012) Microfluidic 3D cell culture: potential
application for tissue-based bioassays. Bioanalysis 4(12):1509–1525
111. Lee J, Lilly GD, Doty RC, Podsiadlo P, Kotov NA. In vitro toxicity testing of
nanoparticles in 3D cell culture. Small. 2009;5(10):NA-NA
112. Fabian E, Landsiedel R, Ma-Hock L, Wiench K, Wohlleben W, van Ravenzwaay B
(2008) Tissue distribution and toxicity of intravenously administered titanium
dioxide nanoparticles in rats. Arch Toxicol 82(3):151–157
113. Recordati C, De Maglie M, Bianchessi S, Argentiere S, Cella C, Mattiello S,
et al. Tissue distribution and acute toxicity of silver after single intravenous
administration in mice: nano-specific and size-dependent effects. Part Fibre
Toxicol. 2016;13(1). https://doi.org/10.1186/s12989/-016-0124-x
114. Asare N, Duale N, Slagsvold HH, Lindeman B, Olsen AK, Gromadzka-
Ostrowska J et al (2016) Genotoxicity and gene expression modulation
of silver and titanium dioxide nanoparticles in mice. Nanotoxicology
10(3):312–321
115. Zhang X-D, Wu H-Y, Wu D, Wang Y-Y, Chang J-H, Zhai Z-B et al (2010)
Toxicologic effects of gold nanoparticles in vivo by different administration
routes. Int J Nanomedicine 5:771–781
116. Kwon J, Kim J, Park S, Khang G, Kang PM, Lee D (2013) Inflammation-
responsive antioxidant nanoparticles based on a polymeric prodrug of
vanillin. Biomacromolecules 14(5):1618–1626
117. Narayanan D, Geena MG, Lakshmi H, Koyakutty M, Nair S, Menon D (2013)
Poly-(ethylene glycol) modified gelatin nanoparticles for sustained delivery
of the anti-inflammatory drug ibuprofen-sodium: an in vitro and in vivo
analysis. Nanomed Nanotechnol Biol Med. 9(6):818–828
118. Hauck TS, Anderson RE, Fischer HC, Newbigging S, Chan WCW (2010) In
vivo quantum-dot toxicity assessment. Small 6(1):138–144
119. Haque MM, Im H-Y, Seo J-E, Hasan M, Woo K, Kwon O-S (2013) Acute
toxicity and tissue distribution of CdSe/CdS-MPA quantum dots after
repeated intraperitoneal injection to mice. J Appl Toxicol 33(9):940–950
120. Chen N, He Y, Su Y, Li X, Huang Q, Wang H et al (2012) The cytotoxicity of
cadmium-based quantum dots. Biomaterials 33(5):1238–1244
121. Nagy A, Hollingsworth JA, Hu B, Steinbrück A, Stark PC, Rios Valdez C et al
(2013) Functionalization-dependent induction of cellular survival pathways
by CdSe quantum dots in primary normal human bronchial epithelial cells.
ACS Nano 7(10):8397–8411
122. Zhan Q, Tang M (2014) Research advances on apoptosis caused by
quantum dots. Biol Trace Elem Res 161(1):3–12
123. Yong K-T, Law W-C, Hu R, Ye L, Liu L, Swihart MT et al (2013) Nanotoxicity
assessment of quantum dots: from cellular to primate studies. Chem Soc
Rev 42(3):1236–1250
124. Fitzpatrick JAJ, Andreko SK, Ernst LA, Waggoner AS, Ballou B, Bruchez MP
(2009) Long-term persistence and spectral blue shifting of quantum dots in
vivo. Nano Lett 9(7):2736–2741
125. Yang RSH, Chang LW, Wu J-P, Tsai M-H, Wang H-J, Kuo Y-C et al (2007)
Persistent tissue kinetics and redistribution of nanoparticles, quantum dot
705, in mice: ICP-MS quantitative assessment. Environ Health Perspect
115(9):1339–1343
126. Liu N, Mu Y, Chen Y, Sun H, Han S, Wang M et al (2013) Degradation
of aqueous synthesized CdTe/ZnS quantum dots in mice: differential
blood kinetics and biodistribution of cadmium and tellurium.
Part Fibre Toxicol. 10:37
127. Ballou B, Lagerholm BC, Ernst LA, Bruchez MP, Waggoner AS (2004)
Noninvasive imaging of quantum dots in mice. Bioconjug Chem 15(1):79–86
128. Larson DR, Zipfel WR, Williams RM, Clark SW, Bruchez MP, Wise FW et al
(2003) Water-soluble quantum dots for multiphoton fluorescence imaging
in vivo. Science 300(5624):1434–1436
129. Hu R, Law W-C, Lin G, Ye L, Liu J, Liu J et al (2012) PEGylated phospholipid
micelle-encapsulated near-infrared PbS quantum dots for in vitro and in
vivo bioimaging. Theranostics 2(7):723–733
130. Pons T, Pic E, Lequeux N, Cassette E, Bezdetnaya L, Guillemin F et al (2010)
Cadmium-free CuInS2/ZnS quantum dots for sentinel lymph node imaging
with reduced toxicity. ACS Nano 4(5):2531–2538
131. Erogbogbo F, Yong K-T, Roy I, Hu R, Law W-C, Zhao W et al (2011) In
vivo targeted cancer imaging, sentinel lymph node mapping and multi-
channel imaging with biocompatible silicon nanocrystals. ACS Nano
5(1):413–423
132. Wang F, Yu L, Monopoli MP, Sandin P, Mahon E, Salvati A et al (2013) The
biomolecular corona is retained during nanoparticle uptake and protects
the cells from the damage induced by cationic nanoparticles until
degraded in the lysosomes. Nanomedicine 9(8):1159–1168
133. Aggarwal P, Hall JB, McLeland CB, Dobrovolskaia MA, McNeil SE (2009)
Nanoparticle interaction with plasma proteins as it relates to particle
biodistribution, biocompatibility and therapeutic efficacy. Adv Drug Deliv
Rev 61(6):428–437
134. Zyuzin MV, Yan Y, Hartmann R, Gause KT, Nazarenus M, Cui J et al (2017)
Role of the protein corona derived from human plasma in cellular
interactions between nanoporous human serum albumin particles and
endothelial cells. Bioconjug Chem 28(8):2062–2068
135. Zhang Y, Zhang Y, Hong G, He W, Zhou K, Yang K et al (2013)
Biodistribution, pharmacokinetics and toxicology of Ag2S near-infrared
quantum dots in mice. Biomaterials 34(14):3639–3646
136. Abbott Chalew TE, Schwab KJ (2013) Toxicity of commercially available
engineered nanoparticles to Caco-2 and SW480 human intestinal epithelial
cells. Cell Biol Toxicol 29(2):101–116
137. Bannunah AM, Vllasaliu D, Lord J, Stolnik S (2014) Mechanisms of
nanoparticle internalization and transport across an intestinal epithelial cell
model: effect of size and surface charge. Mol Pharm 11(12):4363–4373
138. Piret J-P, Vankoningsloo S, Mejia J, Noël F, Boilan E, Lambinon F et al (2012)
Differential toxicity of copper (II) oxide nanoparticles of similar
hydrodynamic diameter on human differentiated intestinal Caco-2 cell
monolayers is correlated in part to copper release and shape.
Nanotoxicology 6(7):789–803
139. Koeneman BA, Zhang Y, Hristovski K, Westerhoff P, Chen Y, Crittenden JC et al
(2009) Experimental approach for an in vitro toxicity assay with non-
aggregated quantum dots. Toxicol in Vitro 23(5):955–962
140. Gerloff K, Albrecht C, Boots AW, Förster I, Schins RPF (2009) Cytotoxicity and
oxidative DNA damage by nanoparticles in human intestinal Caco-2 cells.
Nanotoxicology 3(4):355–364
141. Alkilany AM, Nagaria PK, Hexel CR, Shaw TJ, Murphy CJ, Wyatt MD (2009)
Cellular uptake and cytotoxicity of gold nanorods: molecular origin of
cytotoxicity and surface effects. Small 5(6):701–708
142. Wang L, Nagesha DK, Selvarasah S, Dokmeci MR, Carrier RL (2008) Toxicity
of CdSe nanoparticles in Caco-2 cell cultures. J Nanobiotechnology 6(1):11
143. Jos A, Pichardo S, Puerto M, Sánchez E, Grilo A, Cameán AM (2009)
Cytotoxicity of carboxylic acid functionalized single wall carbon nanotubes
on the human intestinal cell line Caco-2. Toxicol in Vitro 23(8):1491–1496
144. Thubagere A, Reinhard BM (2010) Nanoparticle-induced apoptosis
propagates through hydrogen-peroxide-mediated bystander killing: insights
from a human intestinal epithelium in vitro model. ACS Nano 4(7):3611–3622
145. Rhoads LS, Silkworth WT, Roppolo ML, Whittingham MS (2010) Cytotoxicity
of nanostructured vanadium oxide on human cells in vitro. Toxicol in Vitro
24(1):292–296
146. Häfeli UO, Riffle JS, Harris-Shekhawat L, Carmichael-Baranauskas A, Mark F,
Dailey JP et al (2009) Cell uptake and in vitro toxicity of magnetic
nanoparticles suitable for drug delivery. Mol Pharm 6(5):1417–1428
147. Freese C, Schreiner D, Anspach L, Bantz C, Maskos M, Unger RE et al (2014)
In vitro investigation of silica nanoparticle uptake into human endothelial
cells under physiological cyclic stretch. Part Fibre Toxicol. 11(1):68
148. Feng W, Nie W, Cheng Y, Zhou X, Chen L, Qiu K et al (2015) In vitro and in
vivo toxicity studies of copper sulfide nanoplates for potential photothermal
applications. Nanomed Nanotechnol Biol Med 11(4):901–912
149. Sun D, Liu Y, Yu Q, Zhou Y, Zhang R, Chen X et al (2013) The effects of
luminescent ruthenium(II) polypyridyl functionalized selenium nanoparticles
on bFGF-induced angiogenesis and AKT/ERK signaling. Biomaterials 34(1):
171–180
150. Choi J, Reipa V, Hitchins VM, Goering PL, Malinauskas RA (2011)
Physicochemical characterization and in vitro hemolysis evaluation of silver
nanoparticles. Toxicol Sci 123(1):133–143
151. Ashokan A, Chandran P, Sadanandan AR, Koduri CK, Retnakumari AP,
Menon D et al (2012) Development and haematotoxicological evaluation of
doped hydroxyapatite based multimodal nanocontrast agent for near-
infrared, magnetic resonance and X-ray contrast imaging. Nanotoxicology
6(6):652–666
152. Xia Y, Li M, Peng T, Zhang W, Xiong J, Hu Q et al (2013) In vitro cytotoxicity
of fluorescent silica nanoparticles hybridized with aggregation-induced
emission luminogens for living cell imaging. Int J Mol Sci 14(1):1080–1092
153. Yan M, Zhang Y, Xu K, Fu T, Qin H, Zheng X (2011) An in vitro study of vascular
endothelial toxicity of CdTe quantum dots. Toxicology 282(3):94–103
154. Rizvi SB, Rouhi S, Taniguchi S, Yang SY, Green M, Keshtgar M et al (2014)
Near-infrared quantum dots for HER2 localization and imaging of cancer
cells. Int J Nanomedicine 9:1323–1337
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 20 of 21
155. Xie Y, Williams NG, Tolic A, Chrisler WB, Teeguarden JG, Maddux BLS et al
(2012) Aerosolized ZnO nanoparticles induce toxicity in alveolar type II
epithelial cells at the air-liquid interface. Toxicol Sci 125(2):450–461
156. Lanone S, Rogerieux F, Geys J, Dupont A, Maillot-Marechal E, Boczkowski J et al
(2009) Comparative toxicity of 24 manufactured nanoparticles in human
alveolar epithelial and macrophage cell lines. Part Fibre Toxicol. 6(1):14
157. Hanagata N, Zhuang F, Connolly S, Li J, Ogawa N, Xu M (2011) Molecular
responses of human lung epithelial cells to the toxicity of copper oxide
nanoparticles inferred from whole genome expression analysis. ACS Nano
5(12):9326–9338
158. Murphy FA, Schinwald A, Poland CA, Donaldson K (2012) The mechanism of
pleural inflammation by long carbon nanotubes: interaction of long fibres
with macrophages stimulates them to amplify pro-inflammatory responses
in mesothelial cells. Part Fibre Toxicol 9(1):8
159. Nagy A, Steinbrück A, Gao J, Doggett N, Hollingsworth JA, Iyer R (2012)
Comprehensive analysis of the effects of CdSe quantum dot size, surface
charge, and functionalization on primary human lung cells. ACS Nano 6(6):
4748–4762
160. Guadagnini R, Moreau K, Hussain S, Marano F, Boland S. Toxicity evaluation
of engineered nanoparticles for medical applications using pulmonary
epithelial cells. Nanotoxicology. 2015;9 Suppl 1(sup1):25–32
161. Manshian BB, Soenen SJ, Al-Ali A, Brown A, Hondow N, Wills J et al (2015)
Cell type-dependent changes in CdSe/ZnS quantum dot uptake and toxic
endpoints. Toxicol Sci 144(2):246–258
162. Brunetti V, Chibli H, Fiammengo R, Galeone A, Malvindi MA, Vecchio G et al
(2013) InP/ZnS as a safer alternative to CdSe/ZnS core/shell quantum dots:
in vitro and in vivo toxicity assessment. Nano 5(1):307–317
163. Orlowski P, Krzyzowska M, Zdanowski R, Winnicka A, Nowakowska J,
Stankiewicz W et al (2013) Assessment of in vitro cellular responses of
monocytes and keratinocytes to tannic acid modified silver nanoparticles.
Toxicol in Vitro 27(6):1798–1808
164. Stępnik M, Arkusz J, Smok-Pieniążek A, Bratek-Skicki A, Salvati A, Lynch I et al
(2012) Cytotoxic effects in 3T3-L1 mouse and WI-38 human fibroblasts
following 72 hour and 7 day exposures to commercial silica nanoparticles.
Toxicol Appl Pharmacol 263(1):89–101
165. Jeong SH, Kim HJ, Ryu HJ, Ryu WI, Park Y-H, Bae HC et al (2013) ZnO
nanoparticles induce TNF-αexpression via ROS-ERK-Egr-1 pathway in
human keratinocytes. J Dermatol Sci 72(3):263–273
166. Vankoningsloo S, Piret J-P, Saout C, Noel F, Mejia J, Zouboulis CC et al
(2010) Cytotoxicity of multi-walled carbon nanotubes in three skin cellular
models: effects of sonication, dispersive agents and corneous layer of
reconstructed epidermis. Nanotoxicology 4(1):84–97
167. Kocbek P, Teskac K, Kreft ME, Kristl J. Toxicological aspects of long-term
treatment of keratinocytes with ZnO and TiO2 nanoparticles. Small 2010;
6(17):1908–17
168. Zhang LW, Yu WW, Colvin VL, Monteiro-Riviere NA (2008) Biological
interactions of quantum dot nanoparticles in skin and in human epidermal
keratinocytes. Toxicol Appl Pharmacol 228(2):200–211
169. Guller AE, Generalova AN, Petersen EV, Nechaev AV, Trusova IA, Landyshev
NN et al (2015) Cytotoxicity and non-specific cellular uptake of bare and
surface-modified upconversion nanoparticles in human skin cells. Nano Res
8(5):1546–1562
170. Shukla RK, Sharma V, Pandey AK, Singh S, Sultana S, Dhawan A (2011) ROS-
mediated genotoxicity induced by titanium dioxide nanoparticles in human
epidermal cells. Toxicol in Vitro 25(1):231–241
171. Mukherjee SP, Davoren M, Byrne HJ (2010) In vitro mammalian
cytotoxicological study of PAMAM dendrimers—towards quantitative
structure activity relationships. Toxicol in Vitro 24(1):169–177
172. Peuschel H, Sydlik U, Haendeler J, Büchner N, Stöckmann D, Kroker M, et al.
(2010) c-Src-mediated activation of Erk1/2 is a reaction of epithelial cells to
carbon nanoparticle treatment and may be a target for a molecular
preventive strategy. Biol Chem 391(11):1327–1332.
173. Tsoi KM, Dai Q, Alman BA, Chan WCW (2013) Are quantum dots toxic?
Exploring the discrepancy between cell culture and animal studies. Acc
Chem Res 46(3):662–671
174. Zanganeh S, Spitler R, Erfanzadeh M, Alkilany AM, Mahmoudi M (2016)
Protein corona: opportunities and challenges. Int J Biochem Cell Biol 75:
143–147
Sukhanova et al. Nanoscale Research Letters (2018) 13:44 Page 21 of 21
