PVP-coated AgNPs Research Articles

Physiological evaluation of PVP-coated AgNP in the rat small intestine: an ex vivo approach

Physiological evaluation of PVP-coated AgNP in the rat small intestine: an ex vivo approach

Nano-capsuled thermal interface materials filler using defective multilayered graphene-coated silver nanoparticles

To increase the thermal conductivity of thermal interface materials (TIM), the selection of thermally conductive filler is crucial. In this study, defective graphene-coated silver nanoparticles (Ag NPs) were selected as TIM fillers with low electrical resistivity. Poly-vinylpyrrolidone (PVP) coated Ag NPs were fabricated by polyol process to be used as a precursor, while a multi-layer graphene (MLG) coated layer about 3–4 nm in thickness was formed on the surface of Ag NPs which is 95 nm through a chemical vapor deposition (CVD) process. For application as a metal TIM filler for MLG-coated Ag NPs, the thermal properties of MLG-coated Ag NPs with varying ratios of PVP solution added to the PVP-coated Ag NPs during CVD, were evaluated. Moreover, the peak for crystalline carbon was confirmed through XRD analysis at 26.207°, while the d-spacing was measured to be 3.40 Å. Through Raman analysis, the presence of D peak (1350 cm−1), G peak (1590 cm−1), and 2D peak (2850 cm−1) proved the successful formation of defective MLG on the surface of Ag NPs. Finally, high thermal conductivity of 71 W/(m∙K) with electrical resistivity of 6.0 × 10−8 Ω∙m was obtained when adding 60 wt% PVP solution to PVP-coated Ag NPs during CVD, showing complete isolation among MLG-coated Ag NPs while PVP solution added less than 60 wt% did not prevent Ag NPs from coarsening, increasing its electrical resistivity. Therefore, nano-capsuled TIM fillers composed of defective MLG-coated Ag NPs with high thermal conductivities were obtained to demonstrate their potential for high-performance computing devices in thermal management.

Nanoparticle toxicity may cause testicular dysfunction

Nanoparticle toxicity may cause testicular dysfunction

Interaction of Differently Coated Silver Nanoparticles With Skin and Oral Mucosal Cells.

Silver nanoparticles (AgNP) can be found in different consumer products and various medical devices due to their excellent biocidal properties. Despite extensive scientific literature reporting biological effects of AgNP, there is still a lack of scientific evidence on how different surface functionalization affects AgNP interaction with the human skin and the oral epithelium. This study aimed to investigate biological consequences following the treatment of HaCaT and TR146cells with AgNP stabilized with negatively charged sodium bis(2-ethylhexyl)-sulfosuccinate (AOT), neutral polyvinylpyrrolidone (PVP), and positively charged poly-l-lysine (PLL). All AgNP were characterized by means of size, shape and surface charge. Interactions with biological barriers were investigated invitro by determining cell viability, particle uptake, oxidative stress response and DNA damages following AgNP treatment. Results showed a significant difference in cytotoxicity depending on the surface coating used for AgNP stabilization. All three types of AgNP induced apoptosis, oxidative stress response and DNA damages in cells, but AOT- and PVP-coated AgNP exhibited lower toxicity than positively charged PLL-AgNP. Considering the number of data gaps related to the safe use of nanomaterials in biomedicine, this study highlights the importance of particle surface functionalization that should be considered during design and development of future AgNP-based medical products.

Biodistribution and pulmonary metabolic effects of silver nanoparticles in mice following acute intratracheal instillations

The respiratory tract is the route of entry for accidentally inhaled AgNPs, which can reach the lungs and redistribute to other main organs through systemic circulation. In the present work, we aimed to evaluate silver biodistribution and biological effects after 1 or 2 intratracheal instillations (IT) of two differently sized PVP-coated AgNPs (5 and 50 nm-3 mg/kg) and ionic silver (AgNO3-1 mg/kg bw) in mice. Furthermore, nuclear magnetic resonance (NMR) metabolomics was applied to unveil pulmonary metabolic variations. Animals exposed to 5 nm AgNP (AgNP5) showed higher levels of ionic silver in organs, especially in the lung, spleen, kidney and liver, while animals exposed to 50 nm AgNP (AgNP50) showed higher levels of silver in the blood. Animals exposed to AgNP50 excreted higher amounts of silver than those exposed to AgNP5, which is consistent with higher tissue accumulation of silver in animals exposed to the latter. Lung metabolic profiling revealed several Ag-induced alterations in metabolites involved in different pathways, such as glycolysis and tricarboxylic acid (TCA) cycle, amino acid and phospholipid metabolism, and antioxidant defense. Notably, most of the metabolic changes observed after 1 IT were absent in animals subjected to 2 IT of AgNO3, or reversed for AgNPs, suggesting adaptation mechanisms to cope with the initial insult and recover homeostasis. Graphical abstract.

Effect of differently coated silver nanoparticles on hemostasis

With the emergence of nano-enabled medical devices (MDs) for the use in human medicine, ensuring their safety becomes of crucial importance. Hemocompatibility is one of the major criteria for approval of all MDs in contact with blood (e.g. vascular grafts, stents, or valves). Silver nanoparticles (AgNPs) are among the most used nanomaterials for MDs due to their biocidal activity; however, detailed knowledge on their hemostatic effects is still lacking. This study aimed to evaluate comprehensively AgNPs effects on hemostasis in human blood by exploiting combination of affordable and clinically relevant techniques. Differently stabilized AgNPs were prepared using sodium bis(2-ethylhexyl)sulphosuccinate (AOT), polyvinylpyrrolidone (PVP), poly-L-lysine (PLL), and bovine serum albumin (BSA) as coating agents. They were tested for hemolytic activity, induction of platelet aggregation, plasmatic coagulation, thrombin generation, and hemostasis in whole blood. All AgNPs were found to cause dose-dependent hemolysis. The BSA-, AOT-, and PVP-coated AgNPs delayed plasmatic coagulation, while only PLL-AgNPs inhibited plasmatic coagulation, induced platelet activation, and interfered with hemostasis by delaying clotting time and decreasing clot firmness in whole blood. Obtained results demonstrate that a combination of different techniques should be used for reliable assessment of AgNPs hemostatic effects highlighting the need for a standardized approach in sampling and experimental protocols.

Effect of silver nanoparticle contaminated biosolids on the soil microbial community

This study investigated the effects of AgNPs on soil microbial communities when biosolids, containing AgNPs, were amended into soil. A field-collected sandy loam soil was amended with biosolids containing aged, PVP-coated AgNPs at measured concentrations of 3, 48, 123, 290 and 706 mg Ag kg−1 of soil (dry weight). The control treatment consisted of soil without AgNPs (Con-0) but amended with biosolids. An additional treatment of Ag+ (AgNO3) at 138 mg Ag kg−1 was included as appropriate. The AgNPs were aged in biosolids for 72 h before being spiked into soil. The impact of aged-AgNPs on the in-situ soil microbial community was assessed using a suite of microbial tests that assessed the effects on microbial growth, biomass, activity and diversity. The extractable Ag+ in AgNPs spiked soils increased with increasing AgNP concentrations and ranged from <0.1 to 3.38 mg Ag+ kg−1 soil. The extractable Ag+ in the AgNO3 treatment (i.e., 138 mg Ag kg−1) was 5 times lower than the comparable AgNP treatment (i.e., 123 mg Ag kg−1). A significant impact of AgNPs on the soil microbial community was observed with median inhibitory concentrations (IC50) ranging from 11 to >706 mg Ag kg−1. AgNP treatments showed a 10–64% reduction in microbial activities than the AgNO3 treatment at a similar total Ag concentration. The toxicity of AgNPs were more pronounced overtime, suggesting that Ag+ continued to be released from biosolid-aged AgNPs in the soil environment and likely contributed to the observed toxicity. Emergence of a silver tolerant bacterium (Rhodanobacter sp.) was observed in soils with low to moderately high AgNP concentrations (48 to 290 mg Ag kg−1). Our results suggest that AgNP exposure in soil amended with biosolids may have significant inhibitory effects on the soil microbial community despite their potential sulfidation in biosolid-amended soils.

Enhanced bactericidal efficacy of polymer stabilized silver nanoparticles in conjugation with different classes of antibiotics.

The paper presents the interaction mechanism of silver nanoparticles (AgNPs) with different antibiotics and the antibacterial efficacy of the formed conjugates. The AgNPs used in this study were synthesized from silver nitrate using sodium borohydride as a reducing agent, in the presence of PVP as a protecting agent. Two antibiotics, amikacin and vancomycin with different modes of action, were used to functionalize the synthesized PVP-capped AgNPs. The formation of antibiotic-AgNPs conjugate was confirmed by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and X-ray diffraction (XRD) and the results suggest the conjugation of both drugs to silver nanoparticle surfaces. FTIR results indicate that intermolecular hydrogen bonding exists between PVP-coated AgNPs and antibiotics. The oxygen atom coordinated with PVP was available for interaction with either amine or amide groups of drugs. Further, the antibacterial efficacy of these PVP-capped AgNPs with selected antibiotics was evaluated against Escherichia coli and Staphylococcus aureus by agar well diffusion test. Synergetic bactericidal activity for antibiotic-AgNPs conjugate was observed against both microbes.

Toxic Effects and Molecular Mechanism of Different Types of Silver Nanoparticles to the Aquatic Crustacean Daphnia magna

Silver nanoparticles (AgNPs) have been assessed to have a high exposure risk for humans and aquatic organisms. Toxicity varies considerably between different types of AgNPs. This study aimed to investigate the toxic effects of AgNPs with different particle sizes (40 and 110 nm) and different surface coatings (sodium citrate and polyvinylpyrrolidone, PVP) on Daphnia magna and their mechanisms of action. The results revealed that the citrate-coated AgNPs were more toxic than PVP-coated AgNPs and that the 40 nm AgNPs were more toxic than the 110 nm AgNPs. Transcriptome analysis further revealed that the toxic effects of AgNPs on D. magna were related to the mechanisms of ion binding and several metabolic pathways, such as the "RNA polymerase" pathway and the "protein digestion and absorption" pathway. Moreover, the principal component analysis (PAC) results found that surface coating was the major factor that determines the toxicities compared to particle size. These results could help us better understand the possible mechanism of AgNP toxicity in aquatic invertebrates at the transcriptome level and establish an important foundation for revealing the broad impacts of nanoparticles on aquatic environments.

A rapid approach for measuring silver nanoparticle concentration and dissolution in seawater by UV–Vis

Detection and quantification of engineered nanoparticles (NPs) in environmental systems is challenging and requires sophisticated analytical equipment. Furthermore, dissolution is an important environmental transformation process for silver nanoparticles (AgNPs) which affects the size, speciation and concentration of AgNPs in natural water systems. Herein, we present a simple approach for the detection, quantification and measurement of dissolution of PVP-coated AgNPs (PVP-AgNPs) based on monitoring their optical properties (extinction spectra) using UV–vis spectroscopy. The dependence of PVP-AgNPs extinction coefficient (ɛ) and maximum absorbance wavelength (λmax) on NP size was experimentally determined. The concentration, size, and extinction spectra of PVP-AgNPs were characterized during dissolution in 30ppt synthetic seawater. AgNPs concentration was determined as the difference between the total and dissolved Ag concentrations measured by inductively coupled plasma-mass spectroscopy (ICP-MS); extinction spectra of PVP-AgNPs were monitored by UV–vis; and size evolution was monitored by atomic force microscopy (AFM) over a period of 96h. Empirical equations for the dependence of maximum absorbance wavelength (λmax) and extinction coefficient (ɛ) on NP size were derived. These empirical formulas were then used to calculate the size and concentration of PVP-AgNPs, and dissolved Ag concentration released from PVP-AgNPs in synthetic seawater at variable particle concentrations (i.e. 25–1500μgL−1) and in natural seawater at particle concentration of 100μgL−1.These results suggest that UV–vis can be used as an easy and quick approach for detection and quantification (size and concentration) of sterically stabilized PVP-AgNPs from their extinction spectra. This approach can also be used to monitor the release of Ag from PVP-AgNPs and the concurrent NP size change. Finally, in seawater, AgNPs dissolve faster and to a higher extent with the decrease in NP concentration toward environmentally relevant concentrations.

Influence of silver nanoparticles on benthic oxygen consumption of microbial communities in freshwater sediments determined by microelectrodes

The increased use of silver nanoparticles (AgNPs) will inevitably result in the release of these particles into aquatic environments, with sediments as a substantial sink. However, we do not know whether AgNPs present potential impacts in sediment functioning. In this study, a microcosm approach was constructed, and the potential impacts of AgNPs and PVP-coated AgNPs on oxygen consumption in freshwater sediments (collected from Taihu Lake) were determined using oxygen microelectrodes. To our knowledge, this is the first time that microelectrodes have been used to estimate the impacts of AgNPs in sediments. The steady-state oxygen microprofiles showed that environmental relevant concentration (1 mg/L nano-Ag) did not lead to an apparent change in the oxygen consumption rates of benthic microbial communities in sediment. The addition of 10 mg/L uncoated AgNPs resulted in remarkable differences in the oxygen concentration profiles within 4–5 h and significantly inhibited the oxygen consumption of benthic microbial communities in the upper sediment layer (∼1 mm) after 100 h. Simultaneously, an increase of oxygen consumption in sediment lower zones was observed. These results may suggest that aerobic microorganisms in the upper layer of the sediment reduced metabolic activity to avoid the toxic stress from AgNPs. Concomitantly, facultative aerobes below the metabolically active upper layer switched from fermentation or anaerobic respiration to aerobic respiration as oxygen bioavailability increased in the lower zones of the sediment. In addition, PVP coating reduced the nanotoxicity of AgNPs in benthic microorganisms due to the decreased dissolution of AgNPs in the filtered overlying water, a phenomenon that merits further investigation.

Particle coatings but not silver ions mediate genotoxicity of ingested silver nanoparticles in a mouse model

Incorporation of silver nanoparticles (AgNPs) in toothpaste, food containers, dietary supplements and other consumer products can result in oral exposure to AgNPs and/or silver ions (Ag+) released from the surface of AgNPs. To examine whether ingestion of AgNPs or Ag+ results in genotoxic damage and whether AgNP coatings modulate the effect, we exposed mice orally to 20nm citrate-coated AgNPs, polyvinylpyrrolidone (PVP)-coated AgNPs, silver acetate or respective vehicles at a 4mg/kg dose (equivalent to 800× the EPA reference dose for Ag) for 7days. Genotoxicity was examined in the systemic circulation and bone marrow at 1, 7, and 14days post-exposure. We found that citrate-coated AgNPs induced chromosomal damage in bone marrow and oxidative DNA damage and double strand breaks in peripheral blood. These damages persisted for at least 14days after exposure termination. Because oxidative DNA damage and strand breaks are repaired rapidly, their presence after exposure cessation indicates that citrate-coated AgNPs persist in the body. In contrast, PVP-coated AgNPs and silver acetate did not induce DNA or chromosomal damage at any time point measured. To determine whether coating-dependent genotoxicity is related to different AgNP changes in the gastrointestinal tract, we examined AgNP behavior and fate in an in vitro gastrointestinal digestion model using UV–visible spectroscopy and DLS. Citrate-coated AgNPs were more susceptible to agglomeration than PVP-coated AgNPs in digestive juices with or without proteins. In summary, AgNPs but not Ag+ are genotoxic following oral ingestion. Nanoparticle coatings modulate gastrointestinal transformation and genotoxicity of AgNPs, where higher agglomeration of AgNPs in gastrointestinal juices is associated with higher genotoxicity in tissues. Since genotoxicity is a strong indicator of cancer risk, further long-term studies focusing on cancer are warranted.

High-throughput transcriptomics reveals uniquely affected pathways: AgNPs, PVP-coated AgNPs and Ag NM300K case studies

Understanding the mode of action of nanomaterials (NMs) aids in improving predictions and environmental risk assessment.

Activation of autophagy by elevated reactive oxygen species rather than released silver ions promotes cytotoxicity of polyvinylpyrrolidone-coated silver nanoparticles in hematopoietic cells.

Silver nanoparticles (AgNPs) are the most commonly used engineered nanomaterials in commercialized products because of their antimicrobial activity. Previously, we have shown that polyvinylpyrrolidone (PVP)-coated AgNPs have an anti-leukemia effect against human myeloid leukemia cells; however, whether AgNPs are able to trigger autophagy in normal hematopoietic cells and the role of autophagy in AgNP-induced cytotoxicity remain unclear. In the current study, we observed that AgNPs were taken up by murine pro-B cells (Ba/F3), and then promoted accumulation of autophagosomes, which resulted from the induction of autophagy rather than the blockade of autophagic flux. AgNPs induced cytotoxicity in a dose-dependent manner accompanied by apoptosis and DNA damage through the production of reactive oxygen species (ROS) and the release of silver ions. The ROS-mediated mTOR signaling pathway was responsible for the induction of autophagy. More importantly, the inhibition of autophagy with the addition of 3-methyladenine (3-MA) or silencing of Atg5 significantly attenuated the cytotoxicity of AgNPs in Ba/F3. These findings suggest that autophagy is involved in the cytotoxicity of PVP-coated AgNPs in normal hematopoietic cells, and the inhibition of autophagy is a novel and potent strategy to protect normal hematopoietic cells upon treatment with AgNPs.

Silver nanoparticle behaviour in lake water depends on their surface coating

The present study examines the stability of silver nanoparticles (AgNPs) of three different coatings – citrate (CIT), polyvinyl pyrrolidone (PVP) and lipoic acid (LIP) and two sizes - 20 and 50nm in lake water (LW) over time. Using a combination of asymmetric flow field-flow fractionation (AsFlFFF), surface plasmon resonance (SPR), and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), the influence of size, surface coating, exposure time, as well as the presence and nature of dissolved organic matter (DOM) on the transformation of AgNPs at low environmental concentrations was thoroughly investigated. The results revealed that the AgNP stability in lake water are complex interplay between the surface coating characteristics, exposure time and presence and nature of DOM. Among the studied variables surface coating was found to play the major role of determining AgNPs behaviour in lake water. PVP-coated AgNPs agglomerated to a lesser extent as compared with the CIT- and LIP-AgNPs. For a given surface coating, DOM of pedogenic and aquagenic origin increased the stability of the AgNPs (LW+EPS>LW+SRHA>LW). Moreover, extracellular polymeric substances (EPS; aquagenic origin) stabilized lipoic acid-coated AgNPs more effectively than Suwannee River Humic Acids (SRHA; pedogenic origin), showing that DOM nature has to be also considered for improved understanding the AgNP stability in aquatic environment.

Effects of silver nanoparticles on bacterioplankton in a boreal lake

Summary Silver nanoparticles (AgNPs) are widely used antimicrobial agents and a growing body of evidence suggests that their release into aquatic environments threatens natural bacterial communities and whole ecosystems. However, a knowledge gap exists between the toxic effects of AgNPs found in laboratory studies and their potential impacts in natural environments. In an enclosure experiment conducted in a boreal lake, we exposed natural bacterial communities to AgNPs with two common types of coatings (polyvinylpyrrolidone (PVP) and citrate) under two different exposure regimes, a one‐time (pulse) and a continuous (chronic) addition. AgNP additions increased Ag concentrations to nearly 50 μg L−1 in the highest treatments. We examined bacterial responses (abundance, biomass, production, chlorophyll‐a content and nutrient stoichiometry) over the course of 6 weeks in the summer of 2012. Bacterioplankton exposed to AgNPs initially accumulated Ag over the experimental period regardless of AgNP concentration or coating. After the initial period of increase, Ag in the bacterial size fraction changed largely in concert with bacterial biomass. We found no toxic effects of AgNPs on bacterioplankton abundance, biomass, production or chlorophyll‐a content throughout the experiment. Bacterial production was greater after the pulse addition of PVP‐coated AgNPs and in the chronic addition of PVP‐coated AgNPs at the highest concentrations. Furthermore, AgNPs produced no significant changes in nutrient stoichiometry of the bacterioplankton size fraction. This lack of effects of AgNPs on lake bacterioplankton observed under the natural conditions studied here differs from results of short‐term and laboratory studies of single‐species bacterial cultures. Our results thus indicate AgNP effects in lakes may be less than expected based on standard laboratory experiments, and that additional studies are needed to understand AgNP toxicity under realistic natural conditions in lakes and other ecosystems.

Impact of surface coating and environmental conditions on the fate and transport of silver nanoparticles in the aquatic environment

The role of surface coating (polyvinylpyrrolidone (PVP) and citrate) and water chemistry on the fate and behavior of AgNPs in aquatic microcosms is reported in this study. The migration and transformation of the AgNPs was examined in low (ultrapure water-UPW) and high ionic strength (moderately hard water – MHW) preparations, and in the presence of modeled natural organic matter (NOM) of Suwannee River Fulvic Acid (SRFA). The migration and fate of the AgNPs in the microcosms was validated using a sedimentation-diffusion model and the aggregation behavior was monitored by UV–visible spectrometry (UV–vis). Dissolved and particulate Ag concentrations (% Ag) were analyzed by ultrafiltration methods. Imaging of the AgNPs was captured using transmission electron microscopy (TEM).Results indicate that PVP-coated AgNPs (PVP-AgNPs) remained stable for 28days with similarly distributed concentrations of the PVP-AgNPs throughout the columns in each of the water conditions after approximately 96h (4days). The sedimentation-diffusion model confirmed PVP-AgNP stability in each condition, by showing diffusion dominated transport by using the original unaltered AgNP sizes to fit the parameters. In comparison, citrate AgNPs were largely unstable in the more complex water preparations (MHW). In MHW, aggregation dominated behavior followed by sedimentation/dissolution controlled transport was observed. The addition of SRFA to MHW resulted in small stabilizing effects, to the citrate coated AgNPs, producing smaller sized AgNPs (TEM) and mixed sedimentation and diffusion migration compared the studies absent of SRFA. The results suggest that surface coating and solution chemistry has a major impact on AgNP stability, furthermore the corresponding modeling will support the experimental understanding of the overall fate of AgNPs in the environment.

Toxicological evaluation of silver nanoparticles and silver nitrate in rats following 28 days of repeated oral exposure.

The increasing application of silver nanoparticles (AgNPs) has been raising concerns about their potential adverse effects to human and the environment. However, the knowledge on the systemic toxicity of AgNPs in mammalian systems is still limited. The present study investigated the toxicity of PVP-coated AgNPs in rats treated with repeated oral administration, and compared that with equivalent dose of AgNO3 . Specifically, one hundred male and female rats were orally administrated with particulate or ionic forms of silver (Ag) separately at doses of 0.5 and 1 mgkg-1 body weight daily for 28 days. The results reveal no significant toxic effects of AgNPs and AgNO3 up to 1 mgkg-1 body weight, with respect to the body weight, organ weight, food intake, and histopathological examination. Ag distribution pattern in organs of rats treated with AgNPs was similar to that of AgNO3 treated rats, showing liver and kidneys are the main target organs followed by testis and spleen. The total Ag contents in organs were significantly lower in the AgNPs treated rats than those in the AgNO3 treated rats. However, the comparisons between AgNPs and AgNO3 treatments further indicated more potent of AgNPs in biochemical and hematological parameters in rats, including red blood cell count (RBC), platelet count (PLT), white blood cell count (WBC) and aspartate transaminase (AST). Results of this study suggested that particulate Ag at least partially contributed to the observed toxicity of AgNPs, and both ionic and particulate Ag should be taken into consideration in toxicological evaluation of AgNPs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 609-618, 2017.

In Vitro Effect of 30 nm Silver Nanoparticles on Adipogenic Differentiation of Human Mesenchymal Stem Cells.

With the combined use of silver nanoparticles (Ag NPs) and human bone marrow derived mesenchymal stem cells (hMSCs) in bone tissue engineering, more knowledge of the effects of Ag NPs on hMSCs is required. Up to date, researches mainly focused on the cytotoxicity and genotoxicity of Ag NPs, only few studies discussed their influence on the differentiation of stem cells, especially adipogenic differentiation. In the present study, we investigated the in vitro uptake of 30 nm PVP-coated Ag NPs in hMSCs and their effects on cell viability, cell morphology and adipogenic differentiation of hMSCs. HMSCs were exposed to Ag NPs at concentrations of 25 and 50 μg/mL for 24 hours and at concentrations of 5 and 10 μg/mL throughout the whole differentiation period. Results of cell viability showed that Ag NPs caused time- and dose-dependent toxicity in hMSCs. Transmission electron microscopy (TEM) confirmed the uptake of Ag NPs into cytoplasm of hMSCs. No influence on cell morphology was observed. The 30 nm sized Ag NPs had no effects on adiponectin secretion, lipid droplet formation and the expression of adipogenic marker genes. It is concluded that under our experimental conditions, 30 nm PVP-coated Ag NPs do not influence the adipogenic differentiation of hMSCs in vitro. The present results provide a reference for the usage of 30 nm Ag NPs in the presence of hMSCs in bone tissue engineering.

Synergy Between Polyvinylpyrrolidone-Coated Silver Nanoparticles and Azole Antifungal Against Drug-Resistant Candida albicans.

In the clinical practice, resistance of Candida albicans to antifungal agents has frequently emerged. Silver-nanoparticles (Ag-NPs) have been demonstrated to have the antifungal property. We investigated the potential for synergy between polyvinylpyrrolidone (PVP)-coated Ag-NPs and azole antifungal, such as fluconazole or voriconazole, against drug-resistant C. albicans strain CA10. When antifungal agent was examined alone, fluconazole and voriconazole did not kill drug-resistant C. albicans, and PVP-coated Ag-NPs had only the moderate killing ability. In contrast, the combinational treatment of PVP-coated Ag-NPs with fluconazole or voriconazole was effective in being against the drug-resistant C. albicans. After the combinational treatment, we detected the disruption of cell membrane integrity, the tendency of PVP-coated Ag-NPs to adhere to cell membrane, and the inhibition of budding process. Moreover, after the combinational treatment, the defects in ergosterol signaling and efflux pump functions were detected. Our results suggest that the combinational use of engineered nanomaterials (ENMs), such as PVP-coated Ag-NPs, with the conventional antifungal may be a viable strategy to combat drug-resistant fungal infection.