Coated Silver Nanoparticles Research Articles

Silver-Coated Nanoparticles Combined with Doxorubicin for Enhanced Anticancer Therapy.

Combination therapy with different functional drugs has been proved to be an effective strategy for cancer treatments by achieving cooperative therapeutic efficacy and reducing drug side effects. In this study, a novel combination anticancer system was designed by coating silver nanoparticles in the poly(aspartic acid) (PAsp) shell of polymer micelle via the in situ reduction of silver ions and encapsulating doxorubicin (DOX) into the micellar poly(ε-caprolactone) (PCL) core through hydrophobic interaction. This combination system not only avoided aggregation of the silver nanoparticles but also improved the bioavailability of DOX. As a result, it exhibited enhanced antitumor activity against HepG2 tumor cells compared with single silver-coated or DOX-loaded nanoparticles because of the combined anticancer effects of nanosilver and DOX. Therefore, this combination therapeutic system could be a potential candidate for enhanced anticancer therapy.

Surface Activity of Poly(ethylene glycol)-Coated Silver Nanoparticles in the Presence of a Lipid Monolayer.

We have investigated the surface activity of poly(ethylene glycol) (PEG)-coated silver nanoparticles (Ag-PEG) in the presence or absence of lipid monolayers comprised of monounsaturated dioleoylphosphocholine and dioleoylphosphoglycerol (DOPC/DOPG; 1:1 mol ratio). Dynamic measurements of surface pressure demonstrated that Ag-PEG were surface-active at the air/water interface. Surface excess concentrations suggested that at high Ag-PEG subphase concentrations, Ag-PEG assembled as densely packed monolayers in the presence and absence of a lipid monolayer. The presence of a lipid monolayer led to only a slight decrease in the excess surface concentration of Ag-PEG. Surface pressure-area isotherms showed that in the absence of lipids Ag-PEG increased the surface pressure up to 45 mN m-1 upon compression before the Ag-PEG surface layer collapsed. Our results suggest that surface activity of Ag-PEG was due to hydrophobic interactions imparted by a combination of the amphiphilic polymer coating and the hydrophobic dodecanethiol ligands bound to the Ag-PEG surface. With lipid present, Ag-PEG + lipid surface pressure-area (π-A) isotherms reflected Ag-PEG incorporation within the lipid monolayers. At high Ag-PEG concentrations, the π-A isotherms of the Ag-PEG + lipid films closely resembled that of Ag-PEG alone with a minimal contribution from the lipids present. Analysis of the subphase silver (Ag) and phosphorus (P) concentrations revealed that most of the adsorbed material remained at the air/lipid/water interface and was not forced into the aqueous subphase upon compression, confirming the presence of a composite Ag-PEG + lipid film. While interactions between "water-soluble" nanoparticles and lipids are often considered to be dominated by electrostatic interactions, these results provide further evidence that the amphiphilic character of a nanoparticle coating can also play a significant role.

Toxicity testing of four silver nanoparticle-coated dental castings in 3-D LO2 cell cultures.

To address the controversial issue of the toxicity of dental alloys and silver nanoparticles in medical applications, an in vivo-like LO2 3-D model was constructed within polyvinylidene fluoride hollow fiber materials to mimic the microenvironment of liver tissue. The use of microscopy methods and the measurement of liver-specific functions optimized the model for best cell performances and also proved the superiority of the 3-D LO2 model when compared with the traditional monolayer model. Toxicity tests were conducted using the newly constructed model, finding that four dental castings coated with silver nanoparticles were toxic to human hepatocytes after cell viability assays. In general, the toxicity of both the castings and the coated silver nanoparticles aggravated as time increased, yet the nanoparticles attenuated the general toxicity by preventing metal ion release, especially at high concentrations.

Implications of Pony Lake Fulvic Acid for the Aggregation and Dissolution of Oppositely Charged Surface-Coated Silver Nanoparticles and Their Ecotoxicological Effects on Daphnia magna.

Citrate (Cit) and polyethylenimine (BPEI)-coated silver nanoparticles (AgNPs) were used to understand how the type of capping agents and surface charge affect their colloidal stability, dissolution, and ecotoxicity in the absence/presence of Pony Lake Fulvic Acid (PLFA). In the presence of PLFA, Cit-AgNPs were stabilized, while BPEI-AgNPs were aggregated. The aggregation of BPEI-AgNPs decreased with the time, and their stabilizing effect increased at high PLFA concentration. The dissolution also differed between both AgNPs and was influenced by the PLFA concentration. Generally, BPEI-AgNPs showed a lower amount of dissolved Ag than Cit-AgNPs. The dissolved Ag concentration decreased for both AgNPs at low PLFA concentration (5 mg/L). In contrast, the extent of nanoparticle dissolution increased at high PLFA concentration (30 mg/L) but only for BPEI-AgNPs. In the absence of PLFA, the ecotoxicity of Cit-AgNPs to Daphnia magna was higher than that of BPEI-AgNPs. However, the ecotoxicity of AgNPs in the presence of PLFA was up to 70% lower than in their absence. We demonstrated that the differences in colloidal stability, dissolution, and ecotoxicity may be attributed to the different capping agents, surface charge, and concentration of natural organic matter (NOM) as well as to the formation of dissolved Ag complexes with NOM.

The Antimicrobial Effects of Ciprofloxacin Combined with Green Synthesized Glutathione-coated Silver Nanoparticles on Biofilm Formation of Pseudomonas Aeruginosa

Introdaction: Nowadays, antibiotic resistance is rising at an alarming rate. Essentially, one of the important ways for bacteria such as P. aeruginosa to survive in the presence of antibiotics is biofilm formation. In the current report, we have focused on inhibiting the microbial biofilm formation of P. aeruginosa through combining glutathione (GSH) coated silver nanoparticles (AgNPs) and Ciprofloxacin (Cip). Materials and Methods: AgNPs were biosynthesized using Eucalyptus Camaldulensis leaf extracts and surface modification of AgNPs was done, using glutathione. Synthesized nanoparticles were characterized by FTIR, XRD, DLS, SEM, and CHN tests. Then, 50 isolates of P. aeruginosa were originated from different samples of hospitalized patients from Sina hospital and 24 isolates were selected as a strong biofilm producer using microtiter plate method for further studies. Finally, the synergistic effect of GSH-coated AgNPs and Cip was investigated on biofilm formation of P. aeruginosa . Result: The images of SEM represent the spherical structure of silver nanoparticles with a smooth surface. Also, the results of FTIR, XRD, DLS, SEM, and CHN of AgNPs before and after surface coating confirmed the formation of GSH-coated AgNPs. GSH-coated AgNPs and Cip at a concentration of 1/2 and 1/4 MIC had an inhibitory activity on biofilm formation of 87.5% and 83.4% of P. aeruginosa isolates respectively. Conclusion: This study illustrated that the combination of GSH-coated AgNPs and Cip has a synergistic inhibitory activity on P. aeruginosa biofilm formation.

The in Vitro Effect of Polyvinylpyrrolidone and Citrate Coated Silver Nanoparticles on Erythrocytic Oxidative Damage and Eryptosis

Background/Aims: Silver nanoparticles (AgNPs) are increasingly used as antimicrobial agents and drug carriers in various biomedical fields. AgNPs can encounter erythrocytes either directly following intravenous injection, or indirectly via translocation from the site of administration. However, information regarding the pathophysiological effects and possible mechanism of action of AgNPs on the erythrocytes are still inadequately studied. Thus, the aim of our study was to investigate the mechanism underlying the effect of coating and concentration of AgNPs on mouse erythrocytes in vitro. Methods: We studied the interaction of polyvinylpyrrolidone (PVP) and citrate (CT) coated AgNPs (10 nm) at various concentrations (2.5, 10, 40 µg/ml) with mouse erythrocytes in vitro using various techniques including transmission electron microscopy (TEM), hemolysis, and colorimetric measurement of markers of oxidative stress comprising malondialdehyde (MDA), reduced glutathione (GSH), and catalase (CAT). Intracellular calcium (Ca²⁺) was determined using Fura 2AM fluorescence. Annexin V was quantified using ELISA and the caspase 3 was determined both flurometrically and by western blot technique. Results: Following incubation of the erythrocytes with AgNPs, both PVP- and CT- AgNPs induced significant and dose - dependent increase in hemolysis. TEM revealed that both PVP- and CT- AgNPs were taken up by erythrocytes. The erythrocyte susceptibility to lipid peroxidation measured by MDA was significantly increased in both PVP-and CT- AgNPs. The concentration of GSH and CAT activity were significantly decreased by both types of AgNPs. Additionally, PVP- and CT- AgNPs significantly increased intracellular Ca²⁺ in a dose -dependent manner. Likewise, the concentration of the cellular protein annexin V was significantly and dose - dependently enhanced by both types of AgNPs. Furthermore, PVP- and CT- AgNPs induced significant increase in calpain activity in incubated erythrocytes. Conclusion: We conclude that both PVP- and CT- AgNPs causes hemolysis, and are taken up by erythrocytes. Moreover, we demonstrated that AgNPs induces oxidative stress and eryptosis. These findings provide evidence for the potential pathophysiological effect of PVP-and CT- AgNPs on erythrocyte physiology.

Photo-responsive camptothecin-based polymeric prodrug coated silver nanoparticles for drug release behaviour tracking via the nanomaterial surface energy transfer (NSET) effect.

A hybrid drug delivery system was successfully fabricated by attaching a camptothecin (CPT)-based polymeric prodrug onto the surface of silver nanoparticles (AgNPs). PEG was employed as a macro-RAFT agent in RAFT polymerization to synthesize a branched star copolymer, to which CPT is linked through the photo-responsive o-nitrobenzyl linkage. In vitro tests indicate that the fluorescence of CPT in the polymeric prodrug is quenched by AgNPs based on the nanomaterial surface energy transfer (NSET) effect and the fluorescence recovers when the CPT molecules are released from hybrid nanoparticles. Thus, the variation of fluorescence intensity is bound up with the drug release behaviours, which may enable this AgNP-based drug delivery system to trace the intracellular drug release process and observe the distribution of released CPT in cells.

Pathway and mechanism of nitrogen transformation during composting: Functional enzymes and genes under different concentrations of PVP-AgNPs

Polyvinylpyrrolidone coated silver nanoparticles (PVP-AgNPs) were applied at different concentrations to reduce total nitrogen (TN) losses and the mechanisms of nitrogen bio-transformation were investigated in terms of the nitrogen functional enzymes and genes. Results showed that mineral N in pile 3 which was treated with AgNPs at a concentration of 10 mg/kg compost was the highest (6.58 g/kg dry weight (DW) compost) and the TN loss (47.07%) was the lowest at the end of composting. Correlation analysis indicated that TN loss was significantly correlated with amoA abundance. High throughput sequencing showed that the dominant family of ammonia-oxidizing bacteria (AOB) was Nitrosomonadaceae, and the number of Operational Taxonomic Units (OTUs) reduced after the beginning of composting when compared with day 1. In summary, treatment with AgNPs at a concentration of 10 mg/kg compost was considerable to reduce TN losses and reserve more mineral N during composting.

Mobility of polivinylpyrrolidone coated silver nanoparticles in tropical soils

Experiments in saturated soil columns were performed to investigate the transport and retention of 25 nm and 75 nm silver nanoparticles stabilized with polyvinylpyrrolidone (PVP-AgNPs) in two Brazilian soils (sandy and sandy-clay). The normalized concentration of the PVP-AgNPs was obtained through a flow injection analysis method based on the surface plasmon ressonance effect of the metallic nanoparticles. The use of the ultraviolet–visible spectroscopy (UV–Vis) allows a rapid and low-cost analysis. The obtained breakthrough curves (BCs) were modeled with a deterministic model of solute transport in steady conditions of water flow and considering two regions of non-physical equilibrium; this model allowed the determination of the hydrodynamic parameters. It was found that the process occurs in condition of non-equilibrium, with a low mass transfer for larger NP, and that the process is predominantly advective and affected by the pore size of the soil packed in the columns. The BCs for PVP-AgNPs obtained by UV–Vis spectroscopy were compared with the BCs obtained by ICP-MS and with BCs of the bromide anion, confirming that the nanoparticles have a low retention and few modifications when transported through the soil column. These PVP-AgNPs are highly mobile and can be transported through the studied tropical soils, representing a potential environmental problem, due to the possibility of these materials reaching groundwater. On the contrary, the conservative behavior of PVP-AgNPs in the studied tropical soils, indicates its potential use as tracers, substituting the bromide anion which has been demonstrated to be not a good tracer in the same conditions.

Stable PEG-coated silver nanoparticles – A comprehensive toxicological profile

The present study was purported to assess the toxicological profile of bare and polyethylene glycol (PEG) coated spherical silver nanoparticles (AgNPs) by means of in vitro (on human keratinocytes – HaCat cells) and in vivo non-invasive tests (after intraperitoneal - i.p. administration to mice). Bare and PEG-coated AgNPs were synthesized by applying Turkevich's method slightly modified. The physico-chemical characterization revealed the formation of stable, spherical AgNPs and PEG-AgNPs, with narrow size distributions and mean hydrodynamic sizes in the range of 19 nm and 50 nm, respectively.Toxicity data revealed a dose-dependent safe profile for low concentrations of test compounds (<10 μM) in terms of cell viability, whereas higher concentrations were associated with a high rate of cell mortality. In vivo acute/subacute toxicity data showed no denotive changes in mice health status after i.p. administration. Histological observations of internal organs and the biochemical parameters analyzed together with the other biological observations showed a low toxicity level with no major differences related to control, albeit at skin level a reduced number of mast cells was detected. All these observations provide strong support for the idea that coated silver nanoparticles could be applied as targeted nanocarriers for skin pathologies and diagnostic.

Synergistic Effect of Epicatechin Coated Silver Nanoparticles on Antimicrobial Activity of Gentamicin against Aspergillus Niger

Synergistic Effect of Epicatechin Coated Silver Nanoparticles on Antimicrobial Activity of Gentamicin against Aspergillus Niger

Starch Coated Silver Nanoparticles Using Hygrophila Auriculata L for Controlled Released of Ofloxacin

Starch Coated Silver Nanoparticles Using Hygrophila Auriculata L for Controlled Released of Ofloxacin

Synthesis of epicatechin coated silver nanoparticles for selective recognition of gentamicin

In present study, epicatechin was used as a coating agent to synthesize epicatechin coated silver nanoparticles (ECAgNPs). Conjugation between epicatechin and silver was observed through UV–vis and FTIR spectroscopy, whereas particle size and morphology examined by Dynamic light scattering (DLS), atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Stability of ECAgNPs was not effected by variation in pH, salt concentration and elevated temperature. Furthermore, thirty different antimicrobial drugs were mixed and only gentamicin quench absorbance intensity of ECAgNPs in the pH range of 1–12 without any noticeable interference. Whereas, quenching in the observed concentration range from 0μM to 100μM followed Beer's law. Limit of detection and limit of quantification were found to be 1.28μM and 4.28μM respectively. Furthermore, the synthesized ECAgNPs exhibited remarkable selectivity for gentamicin in tap water, blood plasma and serum.

Effects of Systematic Variation in Size and Surface Coating of Silver Nanoparticles on Their In Vitro Toxicity to Macrophage RAW 264.7 Cells

In literature, varying and sometimes conflicting effects of physicochemical properties of nanoparticles (NPs) are reported on their uptake and effects in organisms. To address this, small- and medium-sized (20 and 50 nm) silver nanoparticles (AgNPs) with specified different surface coating/charges were synthesized and used to systematically assess effects of NP-properties on their uptake and effects in vitro. Silver nanoparticles were fully characterized for charge and size distribution in both water and test media. Macrophage cells (RAW 264.7) were exposed to these AgNPs at different concentrations (0-200 µg/ml). Uptake dynamics, cell viability, induction of tumor necrosis factor (TNF)-α, ATP production, and reactive oxygen species (ROS) generation were assessed. Microscopic imaging of living exposed cells showed rapid uptake and subcellular cytoplasmic accumulation of AgNPs. Exposure to the tested AgNPs resulted in reduced overall viability. Influence of both size and surface coating (charge) was demonstrated, with the 20-nm-sized AgNPs and bovine serum albumin (BSA)-coated (negatively charged) AgNPs being slightly more toxic. On specific mechanisms of toxicity (TNF-α and ROS production) however, the AgNPs differed to a larger extent. The highest induction of TNF-α was found in cells exposed to the negatively charged AgNP_BSA, both sizes (80× higher than control). Reactive oxygen species induction was only significant with the 20 nm positively charged AgNP_Chit.

Investigation on effect of basalin coated silver nanoparticles as antioxidant for alleviating peripheral neuropathy in mice treated with oxaliplatin

A facile, convenient, and green method for the synthesis of BAgNPs by using basalin is proposed in this work. The capping of the basalin on the surface of BAgNP was confirmed by the zeta potential and FTIR findings. Further, we have injected prepared BAgNPs into oxaliplatin-treated mice to alleviate neuropathic pain. The aluminum levels in the DRG were reduced by the chelating activity of BAgNPs. Moreover, behavioral analyses also manifested that the accumulation of aluminum on the DRG might be a reason for neuropathic hyperalgesia. These findings also recommended that the chelation of aluminum by AgNPs could provide an effective remedy to alleviate the symptoms of oxaliplatin-induced neuropathic pain in cancer patients.

Poly-L-arginine Coated Silver Nanoprisms and Their Anti-Bacterial Properties.

The aim of this study was to test the effect of two different morphologies of silver nanoparticles, spheres, and prisms, on their antibacterial properties when coated with poly-L-arginine (poly-Arg) to enhance the interactions with cells. Silver nanoparticle solutions were characterized by UV–visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential, as well as antimicrobial tests. These ultimately showed that a prismatic morphology exhibited stronger antimicrobial effects against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. The minimum bactericidal concentration was found to be 0.65 μg/mL in the case of a prismatic AgNP-poly-Arg-PVP (silver nanoparticle-poly-L-arginine-polyvinylpyrrolidone) nanocomposite. The anticancer cell activity of the silver nanoparticles was also studied, where the maximum effect against a HeLa cell line was 80% mortality with a prismatic AgNP-poly-Arg-PVP nanocomposite at a concentration of 11 μg/mL. The antimicrobial activity of these silver nanocomposites demonstrates the potential of such coated silver nanoparticles in the area of nano-medicine.

Cytotoxicity, genotoxicity and antibacterial activity of poly(vinyl alcohol)-coated silver nanoparticles and farnesol as irrigating solutions

ObjectiveTo evaluate the cytotoxicity, genotoxicity and antibacterial activity of poly(vinyl alcohol)-coated silver nanoparticles (AgNPs-PVA) and farnesol (FAR). DesignThe cytotoxicity (% of cell viability) was evaluated by MTT assay and the genotoxicity (% of DNA in the tail) was evaluated by Comet assay. Root canal disinfection with different irrigating protocols was evaluated ex vivo in human teeth contaminated with Enterococcus faecalis for 21days. Three microbiological samples were collected: initial (after contamination); post-irrigation (after irrigation); and final (after 7days). After each sample, the number of log 10 CFU mL−1 was determined. Statistical analyses was performed using two-way ANOVA and Bonferroni post-hoc tests for MTT assay, Kruskal-Wallis and Dunn post-hoc tests for Cometa and antibacterial assays (α=0.05). ResultsThe MTT assay showed that AgNPs and FAR were less cytotoxic that sodium hypochlorite (NaOCl) and showed a lower% of DNA in the tail, in comparison with H2O2 (positive control − C+). In the post-irrigation microbiological sample, all the irrigating protocols were more effective than C+ (without irrigation). NaOCl/saline, NaOCl/saline/AgNPs-PVA and NaOCl/saline/FAR led to complete bacterial elimination (p >0.05). In comparison with the initial sample, both the post-irrigation and the final samples showed microbial reduction (p < 0.05). ConclusionsAgNPs-PVA and FAR showed low cytotoxicity and genotoxicity, and exhibit potential for use as a final endodontic irrigation protocols.

Dextran coated silver nanoparticles — Chemical sensor for selective cysteine detection

A simple, fast and non-costly method for selective cysteine (Cys) detection, based on optical changes of silver colloids, is developed. For that purpose, stable colloids consisting of silver nanoparticles (Ag NPs) coated with polysaccharide dextran (Dex), isolated from bacterium species Leuconostoc mesenteroides T3, were prepared. The synthesized samples were thoroughly characterized including absorption and FTIR spectroscopy, as well as transmission electron microscopy and X-ray diffraction analysis. The silver colloids display high sensitivity and selectivity towards Cys detection in aqueous solutions. The Ag NPs coated with Dex provide possibility to detect Cys among a dozen amino acids and its detection limit was found to be 12.0μM. The sensing mechanism – red shift of optical absorption – is discussed in terms of the agglomeration of Ag NPs due to formation of hydrogen bonds between Cys molecules attached to different Ag NPs.

Long-term anti-inflammatory efficacy in intestinal anastomosis in mice using silver nanoparticle-coated suture

BackgroundIn our previous study, we coated silver nanoparticles (AgNPs) onto the surface of absorbable braided suture using layer-by-layer deposition and demonstrated significant anti-inflammatory property during the early phase of intestinal anastomosis healing in mice. The present study aimed to further investigate the long-term anti-inflammatory efficacy. MethodsAgNP-coated suture, antibiotic coated suture, and normal suture were respectively used for single layered, interrupted intestinal anastomosis. The anastomotic segments in each group were harvested on day 14, day 21, and day 28 postoperation and investigated for the degree of inflammation by cell infiltration and expression of cytokines as well as collagen deposition. ResultsWhen compared with the control groups, the AgNP-coated suture group showed better histological appearance in the intestinal anastomotic segments at each time point. Immunohistochemistry staining and quantitative evaluation further indicated less macrophage infiltration and decreased production of IL-6, IL-10, and TNF-α (p<0.05). Masson staining showed normal collagen deposition and remodeling at intestinal anastomotic tissue in the AgNP-coated suture group. ConclusionOur study shows that AgNP-coated suture provides better long-term anti-inflammatory efficacy and ideal tissue remodeling in intestinal anastomosis. Despite these findings, clinical trials are still needed for evaluation before medical application.

Rapid biosynthesis of PVP coated silver nanoparticles by Kocuria rosea and their antimicrobial activity

The need for more effective antimicrobial agent and propitious application of nanotechnology in therapeutics and diagnostics has prompted the research on ecofriendly synthesis of silver nanoparticles. The objective of present study was to investigate the antibacterial and antifungal activity of biologically synthesized silver nanoparticles. The silver nanoparticles were synthesized by extracellular method, using soil bacteria Kocuria rosea. The synthesized silver nanoparticles were characterized by UV-Visible spectroscopy, X-ray diffractometry (XRD), transmission electron microscopy (TEM) and fourier transformation infrared spectroscopy (FTIR). On the basis of TEM analysis, the synthesized nanoparticles were found to be spherical with an average size of 30–50 nm. The biologically synthesized silver nanoparticles showed significant antimicrobial activity against pathogens.