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Colloidal silver has been used as an antimicrobial and disinfectant agent. However, there is scarce information on its antitumor potential. The aim of this study was to determine if colloidal silver had cytotoxic effects on MCF-7 breast cancer cells and its mechanism of cell death. MCF-7 breast cancer cells were treated with colloidal silver (ranged from 1.75 to 17.5 ng/mL) for 5 h at 37°C and 5% CO2 atmosphere. Cell Viability was evaluated by trypan blue exclusion method and the mechanism of cell death through detection of mono-oligonucleosomes using an ELISA kit and TUNEL assay. The production of NO, LDH, and Gpx, SOD, CAT, and Total antioxidant activities were evaluated by colorimetric assays. Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of apoptosis, shown an LD50 (3.5 ng/mL) and LD100 (14 ng/mL) (*P < 0.05), significantly decreased LDH (*P < 0.05) and significantly increased SOD (*P < 0.05) activities. However, the NO production, and Gpx, CAT, and Total antioxidant activities were not affected in MCF-7 breast cancer cells. PBMC were not altered by colloidal silver. The present results showed that colloidal silver might be a potential alternative agent for human breast cancer therapy.
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RESEA R C H Open Access
Antitumor activity of colloidal silver on MCF-7
human breast cancer cells
Moisés A Franco-Molina
*
, Edgar Mendoza-Gamboa, Crystel A Sierra-Rivera, Ricardo A Gómez-Flores,
Pablo Zapata-Benavides, Paloma Castillo-Tello, Juan Manuel Alcocer-González, Diana F Miranda-Hernández,
Reyes S Tamez-Guerra, Cristina Rodríguez-Padilla
Abstract
Background: Colloidal silver has been used as an antimicrobial and disinfectant agent. However, there is scarce
information on its antitumor potential. The aim of this study was to determine if colloidal silver had cytotoxic
effects on MCF-7 breast cancer cells and its mechanism of cell death.
Methods: MCF-7 breast cancer cells were treated with colloidal silver (ranged from 1.75 to 17.5 ng/mL) for 5 h at
37°C and 5% CO
2
atmosphere. Cell Viability was evaluated by trypan blue exclusion method and the mechanism of
cell death through detection of mono-oligonucleosomes using an ELISA kit and TUNEL assay. The production of
NO, LDH, and Gpx, SOD, CAT, and Total antioxidant activities were evaluated by colorimetric assays.
Results: Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of
apoptosis, shown an LD
50
(3.5 ng/mL) and LD
100
(14 ng/mL) (*P < 0.05), significantly decreased LDH (*P < 0.05)
and significantly increased SOD (*P < 0.05) activities. However, the NO production, and Gpx, CAT, and Total
antioxidant activities were not affected in MCF-7 breast cancer cells. PBMC were not altered by colloidal silver.
Conclusions: The present results showed that colloidal silver might be a potential alternative agent for human
breast cancer therapy.
Background
Prior to 1938, colloidal silver was widely used to prevent
or treat numerous d iseases. Its use decreased with the
development of antibiotics, such as penicillin and sulfani-
lamide [1]. However, since 1990 there has been a resur-
gence on the use of c olloidal silver as an al ternative
medicine because of increased resistance of bacteria to
antibiotics, and the continuing search for novel and
affordable antimicrobial agents. Colloidal silver is a sus-
pension of submicroscopic metallic silver particles of
about 0.001 mic rons in size, the presence of particles
results in the overall increased surface area [2,3]. Colloi-
dal silver has been used as disinfectant of foods and
water in Mexico; it acts by disabling the oxygen metabo-
lism enzymes in bacteria, which ultimately kills microor-
ganisms. In vitro evidence has shown that bacterial
isolates of Escherichia coli and S taphylococcus aureus are
highly susceptible to colloidal silver treatment [4].
Although the use of colloidal silver as an antimicrobial
agent is recognized [4], there are scarce reports on its use
as antitumor agent; among these, there is a recent report
on the anti-proliferative effect of silver nanoparticles on
human glioblastoma cells (U251) in vitro [5]. Cancer is
an important cause of mortality worldwide and the num-
ber of people who are affected is increasing, being the
breast cancer one of the major ca uses of death in women
[6]. The ori gin of cancer cells can be related to metabolic
alteration, such as mitochondrial increase of glycolysis,
which largel y depends on this metabolic pathway needed
to conver t glucose into pyruvate, for the generation of
ATP to meet cancer cell ene rgy needs. Many cancer cell
types produce ATP by conversion of glucose to lactate
and exhibit lower oxidative phosphorylation, and acceler-
ated glyc olysis e nsures ATP levels compatible with the
demands of fast proliferat ing tumor cells in a hypoxic
environment [7,8]. Furthermore, many reports have
* Correspondence: moyfranco@gmail.com
Laboratorio de Inmunología y Virología. Departamento de Microbiología e
Inmunología. Facultad de Ciencias Biológicas de la Universidad Autónoma
de Nuevo León, San Nicolás de los Garza, N. L. México
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
http://www.jeccr.com/content/29/1/148
© 2010 Franco-Molina et al; licensee BioMed Central L td. This is an Open Access a rticle distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/license s/by/2.0), which permits unrestricted use, distribution, and
reproduction in a ny medium, provided the original work is properly cited.
shown cellular changes resulting from oxidative stress
produced by the generation of reactive oxygen intermedi-
ates (ROI) in tumor cells, which increases the cytotoxicity
activity of the drugs [9]; the oxidativ e str ess is a loss of
balance between ROI production a nd intracellular anti-
oxidants such as superoxide dismutase (SOD), catalase
(CAT), glutathione peroxidase (Gpx), and extracellular
antioxidants.
Although there is a wide range of cytoto xic agents used
in the treatment of breast cancer, such as doxorubicin,
cisplatin, and bl eomycin , the y h ave shown drawbacks in
their use and are not as efficient as expected [10]. There-
fore, it is of great interest to find novel therapeutic agents
against cancer. Hence, we evaluated the effects of colloi-
dal silver on MCF-7 human breast cancer cells growth.
Methods
Main reagents
Penicillin-streptomycin solution, ficoll-hypaque solution,
trypsin-EDTA solution, RPMI-1640 medium, Dulbeccos
modified Eagles medium (DMEM/F-12), and 1% antibio-
tic-antimycotic solution were obta ined from (Life Tech-
nologies GIBCO, Grand Island, NY, USA). Fetal bovine
serum (FBS) was purchased from Sigma-Aldrich (St.
Louis, MO).
Cell Culture
MCF-7 human breast cancer cell line was purchased
from American Type Culture Collection (ATCC, Mana-
ssas, VA, USA) and was maintained in Dulbeccos modi-
fied Eagle s medium supplemented with 10% fetal
bovine serum (FBS) and 1% antibiotic-antimycotic solu-
tion. Cells were grown to confluence at 37°C, and 5%
CO
2
atmosphere.
Isolation of peripheral blood mononuclear cells (PBMC)
Blood from healthy human volunteers was obtain ed
with heparinized syri nges and was place d into sterile
polypropylene tubes. PBMC w ere further isolated by
hystopaque 1077 density gradient centrifugation at 400
g for 30 min at 25°C (Sigma-Aldrich, St. Louis MO,
USA). PBMC were then washed twice with FBS-free
medium (RPMI-1640) a t 250 g for 10 min at 2 5°C and
adjusted to 5 × 10
3
cells/well for analysis.
Colloidal silver
The grenetine-stabilized colloidal silver was purchased
from MICRODYN (Mexico, D.F.) as a 0.35% stock solu-
tion. It w as filtered and diluted to a concentration of
1.75 ng/mL with DMEM/F-12 or RPMI-1640 medium.
Cell viability
Cells (5 × 10
3
cells/well) were plated on 96 flat-bottom
well pl ates, and incubated 24 h at 37°C in 5% CO
2
atmosphere. After incubation, culture medium was
removed, and colloidal silver diluted in the same med-
ium was added at concentrations ranging from 1.75 to
17.5 ng/mL. The plates were then incubated for 5 h at
37°C, and 5% CO
2
atmosphere. Thereafter, the superna-
tant was removed and cells were washed twice with
DMEM/F-12 medium. Cell viability was determined by
the trypan blue exclusion method, a nd cytotoxicity was
expressed as the concentration of 50% (LD
50
)and100%
(LD
100
) cell growth inhibit ion. Results were given as the
mean + SD of three independent experiments.
Mechanism of cell death analysis
Cell death type was assessed by the detection of mono-
oligonucleosomes (histone-associated DNA fragments)
using an ELISA kit (Cell Death Detection ELISA PLUS,
Roche Applie d Science, IN, USA) following the manufac-
turers instructions. In brief, the cytoplasmic lysates from
untreated c ontrols and colloidal silver treated cultures
were transferred to a streptavidin-coated plate supplied by
the manufacturer. A mixture of anti-histone biotin and
anti DNA-POD were added to cell lysates and incubated
for 2 h. The complex was conjugated and then the plate
was read at a wavelength of 405 nm. The increase in
mono-oligonucleosomes production in cells lysates was
calculated as the ratio of the absorbance of colloidal silver
treated cells/absorbance of untreated control. Results were
given as the mean + SD of three independent experiments.
Tunel
Terminal deoxynucleotidyl transferase-me diated dUTP
nick end-labeling (TUNEL) was performed with TACS 2
TdT-DAB In Situ A poptosis Detection kit (Trevigen,
Gaithersburg, Maryland, USA), following the manufac-
turers instructions. Briefly, a fter culture MCF-7 cells at
10
6
cells/well and treated with LD
50
and LD
100
, by 5 h, the
cells were digested with proteinase K at a concentration of
20 μg/mL for 15 minutes. Endogenous peroxidase activity
was quenched with 2% H
2
O
2
for 5 minutes. The cells were
immersed in terminal deoxynucleotidyl transferase (TdT)
buffer. TdT, 1 mM Mn
2+
, and biotinylated dNTP in TdT
buffer were then added to cover the cells and incubated in
a humid atmosphere at 37°C for 60 minutes. The cells
were washed with PBS and incubated with streptavidin-
horseradish peroxidase for 10 minutes. After rinsing with
PBS, the cells were immersed in DAB solution. The cells
were counterstained for 3 minutes with 1% methyl green.
Cells containing fragmented nuclear chromatin character-
istic of apoptosis will exhibit brown nuclear staining that
may be very dark after labeling.
Detection of lactate dehydrogenase (LDH) activity
The conversion of lactate to pyruvate was detected using
the Cytotoxicity Detection Lactate Dehydrogenase kit
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
http://www.jeccr.com/content/29/1/148
Page 2 of 7
(Roche Applied Science, IN, U SA) following the manu-
facturer s instructions. MCF-7 breast cancer cells and
PBMC treated with colloidal silver were washed twice
with ice-cold PBS, harvested by centrifugation at 250 g
for 10 min at 25°C, and the supernatant was used for
the activity assay according to the manufacturer s
instructions. Optical densities resulting from LDH activ-
ity were measured in a microplate reader at 490 nm.
Results were given as the mean + SD of three indepen-
dent experiments.
Nitrite determination
Accumulation of nitrite in the supernatants of control
and treated MCF-7 and PBMC cultures was used as an
indicator of nitric oxide production. Cells were incubated
for 5 h in DMEM/F-12 medium, in the presence or
absence of colloidal silver in triplicates, in a total volume
of 200 μL DMEM/F-12 medium. After in cubation, super-
natants were obtained and nitrite lev els were dete rmined
with the Griess reagent, using NaNO
2
as standard. Opti-
cal densities at 540 nm were then determined in a micro-
plate reader (Bio-Tek Instruments, Inc.).
Determination of intracellular antioxidants
The antioxidants p roduction was measured using the
following kits: Cellular glutathione peroxidase (Gpx)
assay kit (Oxford Biomedical Research, MI, USA), super-
oxide dismutase (SOD) assay kit (Cayman Chemical
Company, MI, USA), and catalase (C AT) assay kit (Cay-
man Chemical Company, MI, USA) according to the
manufacturer s instructions. Briefly, to determine the
activity of Gpx, SOD, and CAT; MCF-7 and PBMC
were incubated with LD
50
(3.5 ng/mL) and LD
100
(14
ng/mL) of colloidal silver for 5 h. Cells were then
washed three times with PBS and sonicated on ice in a
bath-type ultrasonicador (80 Watts output power) for
15-s periods for a total of 4 min; the solution was then
centrifuged at 1500 g for 5 min at 4°C. The obtained
supernatants were used to determine intracellular anti-
oxidants in a microplate reader at 540 nm.
Total antioxidant (extracellular antioxidants)
The total antioxidant production was determined using
the Total Antioxidant Colorimetric Assay Kit (US Bio-
logical, Massachussets, USA) following manufacturers
instructions. Briefly, MCF-7 and PBMC were treated
with LD
50
(3.5 ng/mL) and LD
100
(14 ng/mL) of colloi-
dal silver for 5 h. Thereafter, supernatants were used
to determine antioxidants in a microplate reader at
490 nm.
Statistical analysis
Data represent the mean + SD of triplicates from three
independent experiments. Statistical differences were
obtained using the analysis of variance, and the Dun-
netts and Turkeys tests (SPSS v. 12 program).
Results
Cytotoxic activity of colloidal silver on MCF-7 human
breast cancer cells
As observed in Figure 1, colloidal silver induced dose-
dependent cytotoxic effect on MCF-7 breast cancer
cells; the median lethal dose was (LD
50
) 3.5 ng/mL and
thelethaldose(LD
100
) was 14 ng/mL (*P < 0.05). In
contrast, colloidal silver treatment did not affect PBMC
viability (Figure 1). These LD
50
and LD
100
were used in
further experiments.
Colloidal silver induced apoptosis in MCF-7 breast
cancer cells
The colloidal silver induced the mechanism of cell death
through apoptosis in MCF-7 human breast cancer cell
line, determined by the detection of mono-oligonucleo-
somes. The effects of LD
50
and LD
100
in control cells
only caused non-significant cytotoxicity of 3.05% (P <
0.05), respectively (Figure 2). The TUNEL technique
was also used to detect apoptosis. Labeling of DNA
strand breaks in si tu by TUNEL demonstrated positive
cells that were localized in MCF-7 cells treated with
LD
50
and LD
100
and control, with increased cell apopto-
sis in the LD
50
and LD
100
(Figure 3).
Figure 1 Cell viability of MCF-7 cell line and PBMC treated with
colloidal silver. Cells (5 × 10
3
cells/well) were plated on 96 flat-
bottom well plates, and incubated 24 h at 37°C in 5% CO
2
atmosphere. After incubation, culture medium was removed, and
colloidal silver diluted in the same medium was added at
concentrations ranging from 1.75 to 17.5 ng/mL. The plates were
then incubated for 5 h at 37°C, and 5% CO
2
atmosphere. Thereafter,
the supernatant was removed and cells were washed twice with
DMEM/F-12 medium. Cell viability was determined by the trypan
blue exclusion method, and cytotoxicity was expressed as the
concentration of 50% (LD
50
) and 100% (LD
100
) cell growth
inhibition. The experiments were performed in triplicates; data
shown represent mean + SD of three independent experiments.
*P < 0.05 as compared with untreated cells.
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
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Page 3 of 7
Effect of colloidal silver on the activity of lactate
dehydrogenase in MCF-7 and PBMC
The lactate dehydrogenase activit y significantly (*P <
0.05) decreased i n MCF-7 and PBMC tre ated with col-
loidal silver LD
50
and LD
100
concentrations. Colloidal
silver-treated MCF-7 L D
50
and LD
100
were 1.918 U/mL
and 0.464 U/mL, respectively; untreated MCF-7 cells
value was 1.966 U/mL. Similarly, colloidal silver-treated
PBMC LD
50
and LD
100
concentrations were 0.964 U/mL
and 0.796 U/mL, respectively; compared with the
untreated PBMC value of 1.025 U/mL (Figure 4).
Effect of colloidal silver on nitric oxide production in
MCF-7 and PBMC
Figure 5 shows that NO production was undetectable (*P
< 0.05) in untreated PBMC, and in colloidal silver-trea ted
PBMC at LD
50
and LD
100
concentrations. However, in
untreated MCF-7 cells, nitrites concentration was 1.67
μM, but the colloidal silver-treated MCF-7 at LD
50
and
LD
100
did not affect NO production (*P < 0.05).
Effect of colloidal silver on intracellular and extracellular
antioxidants in MCF-7 and PBMC
The superoxide dismutase activity was significantly (*P <
0.05) increased in colloidal silver-treated MCF-7 at LD
50
(13.54 U/mL) and LD
100
(14.07 U/mL) concentrations,
compared with untreated control cells (10.37 U/mL),
which also signi ficantly (*P < 0. 05) increased in colloidal
silver-treated PBMC at LD
50
(15.92 U/mL) and LD
100
(16.032 U/mL) concentr ations, co mpared with untreated
PBMC (12.458 U/mL) (Figure 6). However, the catalase,
glutathione peroxidase, and total antioxidant activities in
MCF-7 and PBMC treated with colloidal silver did not
differ significantly (*P < 0.05) from those of controls
(Figure 7).
Discussion
Woman breast cancer is the most important cause of mor-
tality in the world [6]. Nowadays, some cytotoxic agents
are used for its treatment including doxorubicin, daunoru-
bicin, bleomycin, and cisplatin. However, they are costly
and known to induce several side effects such as myelo-
suppression, anemia, and most importantly the generation
of cellular resistance. For this, it is important to find alter-
native t herapies or drugs to overcome these drawbacks
[10]. Our in vitro studies showed that colloidal silver
induced a dose-dependent cell death in MCF-7 breast can-
cer cell line through apoptosis, without affecting the viabi-
lity of normal PBMC control cells. Most studies are
focused o n the effect of colloidal silver on bacterial
growth, and the present study might contribute to the
comprehension of this compound on cancer therapy.
It has been known that cancer cells increased the rate of
glycolysis; in this metabolic pathway lactate dehydrogenase
is involved in catalyzing the conversion of py ruvat e into
lactate, which consumes NADH and regenerates NAD
+
[8]. In the present study, we showed that MCF-7 breast
cancer cells treated with colloidal silver, significantly
reduced the dehydrogenase activity, resulting in decreased
NADH/NAD
+
, which in turn induces cell death due to
decreased mitochondrial membrane potential. Death cell
can also be produced by ROI (Reactive Oxygen Intermedi-
ates), and RNI (Rea ctive Nitrogen Intermediate) metabo-
lites. Our results demonstrated that nitric oxide
production was not affected by colloidal silver treatments,
as compared with untreated cells (*P < 0.05), suggesting
that the MCF-7 breast cancer cell death was independent
of nitric oxide production. In addition, it was observed
that colloidal silver did not affect the catalase and glu-
tathione peroxidase activities (*P < 0.05). H owever, the
colloidal silver tre atment increased superoxide dismutase
activity compared with untreated MCF-7 and PBMC (*P <
0.05). This may c ause a redox imbalance, significantly
increasing the SOD activity in response to the production
of high levels of ROI molecules and the lack of activity of
catalase and glutathione peroxidase may allow the toxic
effect of hydrogen peroxide (H
2
O
2
) leading to cell death
[10]. The H
2
O
2
causes cancer cells to undergo apoptosis,
pyknosis, and necr osis. In contrast, normal cells are con-
siderably less vulnerable to H
2
O
2
.Thereasonforthe
increased se nsitivity of tumor cells to H
2
O
2
is not clear
but may be due to lower antioxidant defenses. In fact, a
lower capacity to destroy H
2
O
2
e.g., by catalase, peroxire-
doxins, and GSH peroxidases may cause tumor cells to
grow and proliferate more r apidly than normal cells in
response to low concentrations of H
2
O
2
. It is well known
that H
2
O
2
exerts dose-dependent effects on cell function,
from growth stimulation at very low concen trations to
growth arrest, apoptosis, and eventually necrosis as H
2
O
2
Figure 2 Apoptosis mediated by colloidal silver on MCF-7 cell
line. MCF-7 cells were treated with increasing concentrations of
colloidal silver (1.75 to 17.5 ng/mL) for 5 h. Thereafter, the levels of
mono-oligo nucleosome fragments were quantified using the Cell
Death Detection Kit. The experiments were performed in triplicates;
data shown represent mean + SD of three independent
experiments. *P < 0.05 as compared with untreated cells.
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
http://www.jeccr.com/content/29/1/148
Page 4 of 7
Figure 3 MCF-7 cells stained by the TUNEL technique, counterstained with methyl green.(a) MCF-7 control, showing few brown staining
of cells (arrows). (b) MCF-7 treated with colloidal silver LD
50
(c) and LD
100
showing abundant brown staining of cells (arrows). Original
magnifications, a, b, and c:4.
Figure 4 Effect of colloidal silver on LDH activity in MCF-7 cells
and PBMC. LDH activity was measured by changes in optical
densities due to NAD
+
reduction which were monitored at 490 nm,
as described in the text, using the Cytotoxicity Detection Lactate
Dehydrogenase kit. The experiments were performed in triplicates;
data shown represent mean + SD of three independent
experiments. *P < 0.05 as compared with untreated cells.
Figure 5 Nitric oxide production in colloidal silver-treated
MCF-7 and PBMC. Nitric oxide production at 5 h by colloidal silver-
treated MCF-7 and PBMC, was measured using the nitric oxide
colorimetric assay kit, as described in methods. The experiments
were performed in triplicates; data shown represent mean + SD of
three independent experiments. *P < 0.05 as compared with
untreated cells.
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
http://www.jeccr.com/content/29/1/148
Page 5 of 7
concentrations increase [8]. This dose dependency may be
shifted to the left in tumor cells, making them more sensi-
tive to both t he growth stimulatory and cytotoxic effects
of H
2
O
2
. Whate ver the exact mechanism, the increased
sensitivity of tumor cells to killing by H
2
O
2
may provide
the specificity and therapeutic window for the antitumor
therapy [11]. Colloidal silver is a common substance used
by the Mexican people for disinfecting foods and water for
their consumption, and at this time there is not a report
on potential secondary effects related to this treatment;
this also agreed with a recent study in mice performed in
our laboratory, where colloidal silver was provided in the
water at 10- an d 50-fold higher c oncentrations than the
recommended by the manufacturer during one year with-
out finding any alterations in the evaluated parameters
(fertility, birth, and tumors development) (data not
shown). Howe ver, more studies are needed to elucidate
the mechanism of colloidal silver action, with the aim o f
developing new strategies for the treatment of cancer and
other illness, with lower cost and effectiveness. Therefore,
it can be suggested that colloidal silver treatment may be
used as an alternative treatment against cancer. However,
the mechanism and pathways by which colloidal silver
induced cytotoxic activity on MCF-7 human breast cancer
cell line need further investigation.
Conclusions
The overall results indicated that the colloidal silver has
antitumor activity through induction of apoptosis in
MCF-7 breast cancer cell line, suggesting that colloidal
Figure 6 Superoxide dismutase activity in collo idal silv er-
treated MCF-7 and PBMC. MCF-7 breast cancer cells and PBMC
were treated with colloidal silver for 5 h and then evaluated for
superoxide dismutase (SOD) activity, as explained in methods. The
experiments were performed in triplicates; data shown represent
mean + SD of three independent experiments. *P < 0.05 as
compared with untreated cells.
Figure 7 Effect of the colloidal silver on the intracellular and extracellular antioxidants. MCF-7 breast cancer cells and PBMC were treated
with colloidal silver for 5 h and the antioxidants production were measured as described in methods, using colorimetric assay kits. a) Gpx
activity, b) Catalase activity, c) Total antioxidant production. The experiments were performed in triplicates; data shown represent mean + SD of
three independent experiments. *P < 0.05 as compared with untreated cells.
Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
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Page 6 of 7
silver might be a potential alternative agent for human
breast cancer therapy.
List of abbreviations
PBMC: peripheral blood mononuclear cells; LDH: lactate dehydrogenase; NO:
nitric oxide; Gpx: glutathione peroxidase; SOD: superoxide dismutase; CAT:
catalase; ROI: reactive oxygen intermediates.
Acknowledgements
This work was supported by research grant PROMEP/103-5/07/2523 from the
Proyecto de Apoyo a la Incorporación de nuevos Profesores de Tiempo
Completo to Moisés A. Franco-Molina, and by research grant number
GCN003-09 PAICYT UANL.
Authors contributions
MAFM conceived of the study, participated in its design and coordination,
performed the statistical analysis and drafted the manuscript. EMG
participated in drafting the manuscript. CASR carried out the proliferation,
cell viability, apoptosis, and antioxidants assays, and drafted the manuscript.
RAFG participated in drafting the manuscript. PZB participated in the design
of the study and statistical analysis. PCT carried out Tunel Assay. JMAG
participated in the draft preparation. DFMH participated in drafting the
manuscript. RSTG and CRP participated in the design of study. All authors
read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 22 July 2010 Accepted: 16 November 2010
Published: 16 November 2010
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doi:10.1186/1756-9966-29-148
Cite this article as: Franco-Molina et al.: Antitumor activity of colloidal
silver on MCF-7 human breast cancer cells. Journa l of Experimental &
Clinical Cancer Research 2010 29:148.
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Franco-Molina et al. Journal of Experimental & Clinical Cancer Research 2010, 29:148
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... Furthermore, alloying of Mg with elements like silver (Ag) holds the potential to additionally influence the degradation rate, mechanical properties, and biological response. Mg-Ag alloys have been already shown to have antibacterial effects [17], and they may also prevent carcinogenic progression as Ag also possesses anticancer properties [18,19]. Ensuring tumor cell-specific cytotoxicity and the simultaneous integrity of adjacent healthy cells is one major challenge when investigating Mg-based materials for the use in cancer therapy. ...
... The IC 50 of AgNO 3 has been reported at 6.75 µM for H-ras transformed 5RP7 (rat embryonic fibroblasts) [72] and between 0.19 and 0.37 mM for Hela cells [73]. For Ag-ions and colloidal Ag, other authors have reported an IC 50 of 0.31 mM and 32.45 µM, respectively, for breast cancer cells [19,74]. Our results showed that the concentration of released Ag (0.7 nM) was not comparable to the IC 50 values reported in the other publications. ...
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Osteosarcoma is one of the most common cancers in young adults and is commonly treated using surgery and chemotherapy. During the past years, these therapy approaches improved but failed to ameliorate the outcomes. Therefore, novel, targeted therapeutic approaches should be established to enhance treatment success while preserving patient's quality of life. Recent studies suggest the application of degradable magnesium (Mg) alloys as orthopedic implants bearing a potential antitumor activity. Here, we examined the influence of Mg-based materials on an osteosarcoma-fibroblast coculture. Both, Mg and Mg–6Ag did not lead to tumor cell apoptosis at low degradation rates. Instead, the Mg-based materials induced cellular dormancy in the cancer cells indicated by a lower number of Ki-67 positive cancer cells and a higher p38 expression. This dormancy-like state could be reversed by reseeding on non-degrading glass slides but could not be provoked by inhibition of the protein kinase R-like endoplasmic reticulum kinase. By investigating the influence of the disjunct surface-near effects of the Mg degradation on cell proliferation, an increased pH was found to be a main initiator of Mg degradation-dependent tumor cell proliferation inhibition.
... This can lead to a redox imbalance and elevated H 2 O 2 levels. Healthy cells are less sensitive to H 2 O 2 due to an intact antioxidant defense [40]. Additionally, Ag may reduce the expression of proinflammatory cytokines (TNF-α, IL-12, VEGF) in fibroblasts [41]. ...
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Cancer metastases are the most common causes of cancer-related deaths. The formation of secondary tumors at different sites in the human body can impair multiple organ function and dramatically decrease the survival of the patients. In this stage, it is difficulty to treat tumor growth and spreading due to arising therapy resistances. Therefore, it is important to prevent cancer metastases and to increase subsequent cancer therapy success. Cancer metastases are conventionally treated with radiation or chemotherapy. However, these treatments elicit lots of side effects, wherefore novel local treatment approaches are currently discussed. Recent studies already showed anticancer activity of specially designed degradable magnesium (Mg) alloys by reducing the cancer cell proliferation. In this work, we investigated the impact of these Mg-based materials on different steps of the metastatic cascade including cancer cell migration, invasion, and cancer-induced angiogenesis. Both, Mg and Mg–6Ag reduced cell migration and invasion of osteosarcoma cells in coculture with fibroblasts. Furthermore, the Mg-based materials used in this study diminished the cancer-induced angiogenesis. Endothelial cells incubated with conditioned media obtained from these Mg and Mg–6Ag showed a reduced cell layer permeability, a reduced proliferation and inhibited cell migration. The tube formation as a last step of angiogenesis was stimulated with the presence of Mg under normoxia and diminished under hypoxia.
... Moreover, radiation-induced AgNPs in silver nitrate solutions could be successfully applied for radiation detection and dosimetry [22,23] and dose enhancement in radiotherapy applications [19,[24][25][26]. AgNPs are an exciting alternative for dose enhancement in radiation therapy due to their inexpensive cost compared to gold nanoparticles [25] and antitumor activity [27,28]. The silver nitrate dosimeter features a linear response and good measurements reproducibility [22]. ...
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The dosimetric characteristics of hydrogel dosimeters based on polyacrylamide (PAC) as a capping agent incorporating silver nitrate as a radiation-sensitive material are investigated using UV-Vis spectrophotometry within the dose range 0–100 Gy. Glycerol was used in the hydrogel matrix to promote the dosimetric response and increase the radiation sensitivity. Upon exposing the PAC hydrogel to γ-ray, it exhibits a Surface Plasmon Resonance (SPR) band at 453 nm, and its intensity increases linearly with absorbed doses up to 100 Gy. The results are compared with the silver nitrate gel dosimeter. Glycerol of 15% in the hydrogel matrix enhances the radiation sensitivity by about 30%. PAC hydrogel dosimeter can be considered a near water equivalent material in the 400 keV–20 MeV photon energy range. At doses less than 15 Gy, the PAC hydrogel dosimeter retains higher radiation sensitivity than the gel dosimeter. The total uncertainty (2σ) of the dose estimated using this hydrogel is about 4%. These results may support the validity of using this hydrogel as a dosimeter to verify radiotherapy techniques and dose monitoring during blood irradiation.
... They demonstrated anti-tumor activity in several studies via light absorption that can promote photo-thermal elimination of cancer cells. Meanwhile, the scattered light can be used for imaging for diagnostics [160,171]. ...
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Over the last decades, the global life expectancy of the population has increased, and so, consequently, has the risk of cancer development. Despite the improvement in cancer therapies (e.g., drug delivery systems (DDS) and theranostics), in many cases recurrence continues to be a challenging issue. In this matter, the development of nanotechnology has led to an array of possibilities for cancer treatment. One of the most promising therapies focuses on the assembly of hierarchical structures in the form of nanoclusters, as this approach involves preparing individual building blocks while avoiding handling toxic chemicals in the presence of biomolecules. This review aims at presenting an overview of the major advances made in developing nanoclusters based on polymeric nanoparticles (PNPs) and/or inorganic NPs. The preparation methods and the features of the NPs used in the construction of the nanoclusters were described. Afterwards, the design, fabrication and properties of the two main classes of nanoclusters, namely noble-metal nanoclusters and hybrid (i.e., hetero) nanoclusters and their mode of action in cancer therapy, were summarized.
... AgNPs are now considered a valuable and non-traditional alternative to antibiotics with high antimicrobial potential against multidrugresistant (MDR) Gram-positive and Gram-negative bacterial pathogens [19]. It was also reported that AgNPs inhibited the proliferation of human glioblastoma cells [20] as well as human breast cancer (MCF-7) cells [21]. It was also found that AgNPs stimulated pro-apoptotic genes leading to interference with normal cellular functions and induction of programmed cell death. ...
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Background Resistance to antibiotics and anticancer therapy is a serious global health threat particularly in immunosuppressed cancer patients. Current study aimed to estimate the antibacterial and anticancer potentials of short-term exposure to extremely low frequency electromagnetic field (ELF-EMF) and silver nanoparticles (AgNPs) either in sole or combined form. Methods Antibacterial activity was evaluated via determination of the bacterial viable count reduction percentage following exposure, whereas their ability to induce apoptosis in breast cancer (MCF-7) cell line was detected using annexin V-fluorescein isothiocyanate and cell cycle analysis. Also, oxidative stress potential and molecular profile were investigated. Results ELF-EMF and AgNPs significantly ( p < 0.01) reduced K. pneumonia viable count of compared to that of S. aureus in a time dependent manner till reaching 100% inhibition when ELF-EMF was applied in combination to 10 µM/ml AgNPs for 2 h. Apoptosis induction was obvious following exposure to either ELF-EMF or AgNPs, however their apoptotic potential was intensified when applied in combination recording significantly ( p < 0.001) induced apoptosis as indicated by elevated level of MCF-7 cells in the Pre G1 phase compared to control. S phase arrest and accumulation of cells in G2/M phase was observed following exposure to AgNPs and EMF, respectively. Up-regulation in the expression level of p53, iNOS and NF-kB genes as well as down-regulation of Bcl-2 and miRNA-125b genes were detected post treatment. Conclusions The antibacterial and anticancer potentials of these agents might be related to their ability to induce oxidative stress, suggesting their potentials as novel candidates for controlling infections and triggering cancer cells towards self-destruction.
... Importantly, the presence of silver coating of TLSN samples had no detrimental effect on cell metabolism of human OB; however, osteosarcoma Saos-2 cells proliferation and differentiation were affected by the presence of silver (Fig. 3A). Some studies have shown lower silver cytotoxic thresholds (0.014 ppm) for malignant cells than those of other mammalian cells [48,49], which could explain our results. ...
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Additive manufacturing allows for the production of porous metallic implants for use in orthopaedics, providing excellent mechanical stability and osseointegration. However, the increased surface area of such porous implants also renders them susceptible to bacterial colonization. In this work, two trabecular porous Ti6Al4V alloys produced by electron beam melting were investigated for their osteocompatibility and antimicrobial effects, comparing samples with a silver-coated surface to uncoated samples. Dense grit-blasted Ti samples were used for comparison. The porous samples had pore sizes of 500–600 μm and 5 to 10 μm surface roughness, the silver-coated samples contained 7 at.% Ag, resulting in a cumulative Ag release of 3.5 ppm up to 28 days. Silver reduced the adhesion of Staphylococcus aureus to porous samples and inhibited 72 h biofilm formation by Staphylococcus epidermidis but not that of S. aureus. Primary human osteoblast adhesion, proliferation and differentiation were not impaired in the presence of silver, and expression of osteogenic genes as well as production of mineralized matrix were similar on silver-coated and uncoated samples. Our findings indicate that silver coating of porous titanium implants can achieve antimicrobial effects without compromising osteocompatibility, but higher silver contents may be needed to yield a sustained protection against fast-growing bacteria.
Article
Glioblastoma multiforme is an aggressive, invasive, fatal primary heterogenic brain tumor. New treatments have not significantly improved the dismal survival rate. Low-level laser therapy reports indicate different tumor cells respond distinctly to low-level laser therapy based on laser dose (J/cm2) or with nanotherapeutics. We investigated the effects of pairing two optical property-driven treatment agents—a low-level laser on glioblastoma multiforme (U251) using an He-Ne laser (632.8 nm) with 18.8 nm spherical Ag-PMMA-PAA nanoparticles, with an absorbance peak at 400 nm with a broad shoulder to 700 nm. The He-Ne treatment parameters were power (14.87 ± 0.3 mW), beam diameter (0.68 cm), and exposure time 5 min leading to a 12.28 J/cm2 dose. A dose of 12.28 J/cm2 was applied to Ag-PMMA-PAA nanoparticle concentrations (110–225 μM). An amount of 110 μM Ag-PMMA-PAA nanoparticles combined with an He-Ne dose at 18 h yielded 23% U251 death compared to He-Ne alone which yielded 8% U251 death. A 225 μM Ag-PMMA-PAA nanoparticle He-Ne combination resulted in an earlier, more significant, U251 death of 38% at 6 h compared to 30% with 225 μM alone at 18 h. Both treatment agents possess inherent physical and functional properties capable of redesign to enhance the observed cell death effects. Our results provide evidence supporting next-step studies to test “the redesign hypothesis” that these paired optical-driven agents provide a tunable platform that can generate significant U251 cell death increase.
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Utilizing microwave combustion method Co3-xCuxO4 (x = 0 and 0.5) nanoparticles were prepared utilizing l-alanine as fuel. The phase and crystal structure of Co3O4 and Cu: Co3O4 nanoparticles are studied employing X-ray diffraction technique, which further ensured the phase formation and crystallite size was determined. The crystallite size was observed to be 27.39 and 39.22 nm respectively for pure and Cu:Co3O4 nanoparticles respectively. HRSEM images of the prepared samples unveiled spherical morphology. The presence of Cu, Co and O is observed through Energy dispersive X-ray spectra. Optical bandgap values were assessed and they were observed to lie within 2.87–2.97 eV. FT-IR spectra peaks at 573 and 664 cm⁻¹ were responsible for Co³⁺ of octahedral sites besides Co²⁺ of tetrahedral sites respectively. The M-H loops exhibited super paramagnetic behaviour. Furthermore, we have investigated the various concentrations of Co1-xCuxO (x = 0 and 0.5) nanoparticles towards potential cytotoxicity effect against the A549 human lung epithelial cancer cell lines.
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The overview of this review article depends on the various techniques of formation of silver nanoparticles and different application take place in medicinal point of view. The branch of nanotechnology plays an important role in medical science research. In this different nanoparticle is synthesized which have various application in gene delivery, drug delivery and reduce the toxic effect of drugs in the human body and also act as an antibacterial in pharmaceutical industries. In recent days silver nanoparticles have had an important role due to their optical and catalytic properties. A large number of different particles or methods are used to prepare the different shapes of silver nanoparticles used in drug delivery. Different shapes of nanoparticles have increased their demand in various researches depend on medicinal uses. Silver nanoparticle preparation can be studied by 3 techniques related to irradiations, chemicals, bacteria, fungi, and plants. Nanomedicine have a large number of advantages in treating various chronic diseases by using biological agents, chemotherapeutic agents, and used to deliver the drug to a specific site of the body. A silver nanoparticle is prepared for detection tool to detect the adverse effect of diseases on the target cell. Nanoparticles are used in cancer therapy to remove the damaged cell of the body.
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The integration of silver nanoparticles (Ag NPs) with mesoporous silica nanoparticles (MSNs) protects the former from aggregation and promotes the controlled release of silver ions, resulting in therapeutic significance on cancer and infection. The unique size, shape, pore structure and silver distribution of silver mesoporous silica nanoparticles (Ag-MSNs) embellish them with the potential to perform combined imaging and therapeutic actions via modulating optical and drug release properties. Here, we comprehensively review the recent progress in the fabrication and application of Ag-MSNs for combination therapies for cancer and infection. We first elaborate on the fabrication of star-shaped structure, core-shell structure, and Janus structure Ag-MSNs. We then highlight Ag-MSNs as a multifunctional nanoplatform to surface-enhanced Raman scattering-based detection, non-photo-based cancer theranostics and photo-based cancer theranostics. In addition, we detail Ag-MSNs for combined antibacterial therapy via drug delivery and phototherapy. Overall, we summarize the challenges and future perspectives of Ag-MSNs that make them promising for diagnosis and therapy of cancer and infection.
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Background Nanoparticles possess exceptional physical and chemical properties which led to rapid commercialisation. Silver nanoparticles (Ag-np) are among the most commercialised nanoparticles due to their antimicrobial potential. Ag-np based cosmetics, therapeutic agents and household products are in wide use, which raised a public concern regarding their safety associated with human and environmental use. No safety regulations are in practice for the use of these nanomaterials. The interactions of nanomaterials with cells, uptake mechanisms, distribution, excretion, toxicological endpoints and mechanism of action remain unanswered. Results Normal human lung fibroblasts (IMR-90) and human glioblastoma cells (U251) were exposed to different doses of Ag-nps in vitro. Uptake of Ag-nps occurred mainly through endocytosis (clathrin mediated process and macropinocytosis), accompanied by a time dependent increase in exocytosis rate. The electron micrographs revealed a uniform intracellular distribution of Ag-np both in cytoplasm and nucleus. Ag-np treated cells exhibited chromosome instability and mitotic arrest in human cells. There was efficient recovery from arrest in normal human fibroblasts whereas the cancer cells ceased to proliferate. Toxicity of Ag-np is mediated through intracellular calcium (Ca2+) transients along with significant alterations in cell morphology and spreading and surface ruffling. Down regulation of major actin binding protein, filamin was observed after Ag-np exposure. Ag-np induced stress resulted in the up regulation of metallothionein and heme oxygenase -1 genes. Conclusion Here, we demonstrate that uptake of Ag-np occurs mainly through clathrin mediated endocytosis and macropinocytosis. Our results suggest that cancer cells are susceptible to damage with lack of recovery from Ag-np-induced stress. Ag-np is found to be acting through intracellular calcium transients and chromosomal aberrations, either directly or through activation of catabolic enzymes. The signalling cascades are believed to play key roles in cytoskeleton deformations and ultimately to inhibit cell proliferation.
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The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of Ag nanoparticles on microorganisms and antimicrobial mechanism have not been revealed clearly. Stable Ag nanoparticles were prepared and their shape and size distribution characterized by particle characterizer and transmission electron microscopic study. The antimicrobial activity of Ag nanoparticles was investigated against yeast, Escherichia coli, and Staphylococcus aureus. In these tests, Muller Hinton agar plates were used and Ag nanoparticles of various concentrations were supplemented in liquid systems. As results, yeast and E. coli were inhibited at the low concentration of Ag nanoparticles, whereas the growth-inhibitory effects on S. aureus were mild. The free-radical generation effect of Ag nanoparticles on microbial growth inhibition was investigated by electron spin resonance spectroscopy. These results suggest that Ag nanoparticles can be used as effective growth inhibitors in various microorganisms, making them applicable to diverse medical devices and antimicrobial control systems.
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Oxidative stress resulting from an imbalance between radical-generating and radical scavenging systems plays an important role in the pathogenesis of pulmonary fibrosis. Epigallocatechin-3-gallate (EGCG), a polyphenol and a major component of green tea, possess a potent antioxidant property. This study was designed to evaluate the potential antioxidative activity of EGCG in the plasma and lungs during bleomycin induced experimental pulmonary fibrosis. Intratracheal administration of bleomycin (6.5 U/kg body weight) to rats resulted in significant reduction of body weight, enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase) and non-enzymic antioxidants (reduced glutathione, vitamin C, vitamin E and vitamin A). Elevations in lung W/D (wet weight/dry weight) ratio, hydroxyproline content was observed with a synchronized increase in lipid peroxidation markers (thiobarbituric acid reactive substances and hydroperoxides). Intraperitoneal administration of EGCG at a dose of 20 mg/kg body weight significantly improved the body weight, enzymic and non enzymic antioxidants and considerably decreased the W/D ratio, hydroxyproline and lipid peroxidation marker levels. Histological observations also correlated with the biochemical parameters. Thus, this study confirms the beneficial use of EGCG in alleviating the oxidative stress induced during pulmonary fibrosis.
Article
MCF-7 human breast cancer cells propagated in vitro were treated with adenosine derivatives added to the culture medium. The effects on cell proliferation, glycolysis, and glutaminolysis were investigated. Of all adenosine derivatives tested, AMP was the most efficient inhibitor of cell proliferation. In AMP-treated cells, DNA synthesis decreased, whereas RNA and protein syntheses rose normally with time. In terms of carbohydrate metabolism, lactate production from glucose was drastically reduced; therefore, most of lactate produced must have been derived from glutamine. Increases in the enzyme activities involved in glutamate degradation and in the malate-aspartate shuttle were observed. In contrast, actual glycolytic flux rates declined, whereas key glycolytic enzyme activities increased. Metabolites such as fructose 1,6-bisphosphate and pyruvate accumulated in AMP-arrested cells. Based on the lowered NAD level in the AMP-treated cells, lactate dehydrogenase, but not malate dehydrogenase, was impaired; thereby the whole of glycolysis was inhibited. In compensation, glutamine catabolism was increased. NAD concentrations fell drastically because of the known inhibition of P-ribose-PP synthesis through heightened intracellular AMP levels. A hypothetical metabolic scheme to explain these results and to show how extracellular AMP may influence carbohydrate metabolism and cell proliferation is presented.
Article
Silver has a long and intriguing history as an antibiotic in human health care. It has been developed for use in water purification, wound care, bone prostheses, reconstructive orthopaedic surgery, cardiac devices, catheters and surgical appliances. Advancing biotechnology has enabled incorporation of ionizable silver into fabrics for clinical use to reduce the risk of nosocomial infections and for personal hygiene. The antimicrobial action of silver or silver compounds is proportional to the bioactive silver ion (Ag(+)) released and its availability to interact with bacterial or fungal cell membranes. Silver metal and inorganic silver compounds ionize in the presence of water, body fluids or tissue exudates. The silver ion is biologically active and readily interacts with proteins, amino acid residues, free anions and receptors on mammalian and eukaryotic cell membranes. Bacterial (and probably fungal) sensitivity to silver is genetically determined and relates to the levels of intracellular silver uptake and its ability to interact and irreversibly denature key enzyme systems. Silver exhibits low toxicity in the human body, and minimal risk is expected due to clinical exposure by inhalation, ingestion, dermal application or through the urological or haematogenous route. Chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to deposition of silver metal/silver sulphide particles in the skin (argyria), eye (argyrosis) and other organs. These are not life-threatening conditions but cosmetically undesirable. Silver is absorbed into the human body and enters the systemic circulation as a protein complex to be eliminated by the liver and kidneys. Silver metabolism is modulated by induction and binding to metallothioneins. This complex mitigates the cellular toxicity of silver and contributes to tissue repair. Silver allergy is a known contra-indication for using silver in medical devices or antibiotic textiles.
Article
One major pathogenesis in degenerative disorders of the central nervous system (CNS), including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and ischemia, is the oxidative stress induced by reactive oxygen species (ROS). The present study investigated the protective effect of colloidal silver, which is widely marketed as a dietary supplement for diseases like diabetes, AIDS, cancer, and various infections, upon the oxidative brain damage induced by H(2)O(2) or naphthazarin treatment. LDH release from primary cultured astrocytes was enhanced by naphthazarin treatment, and this elevation of the LDH concentration in medium was blocked by colloidal silver treatment. However, hydrogen peroxide was little affected by the colloidal silver. Fluorescence of DCF (peroxides) increased in astrocytes incubated with hydrogen peroxide or naphthazarin compared to the control. When exposed to naphthazarin-induced cells, ROS formation appeared to be reduced by colloidal silver. However, intracellular ROS formation in hydrogen peroxide-treated cells slightly reduced by colloidal silver. These results suggest that colloidal silver has a protective activity against the oxidative stress induced by naphthazarin, but not by hydrogen peroxide.
Article
Colloidal silver nanoparticles were prepared by reducing silver nitrate with sodium borohydride. The synthesized silver particles show an intense surface plasmon band in the visible region. The work reported here describes the interaction between nanoscale silver particles and various DNA bases (adenine, guanine, cytosine, and thymine), which are used as molecular linkers because of their biological significance. In colloidal solutions, the color of silver nanoparticles may range from red to purple to orange to blue, depending on the degree of aggregation as well as the orientation of the individual particles within the aggregates. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and absorption spectroscopy were used to characterize the assemblies. DNA base-induced differential silver nanoparticle aggregation was quantified from the peak separation (relates to color) of surface plasmon resonance spectroscopy (SPRS) and the signal intensity of surface-enhanced Raman scattering (SERS), which rationalize the extent of silver-nucleobase interactions.
Interaction of DNA bases with silver nanoparticles: assembly quantified throughout SPRS and SERS. Colloid Interface
  • Jana S S Basu
  • S Parde
Basu S, Jana S, Parde S, Pal T: Interaction of DNA bases with silver nanoparticles: assembly quantified throughout SPRS and SERS. Colloid Interface 2008, 321(2):288-93.