PVP-coated AgNPs Research Articles

Sulfidation Processes of PVP-Coated Silver Nanoparticles in Aqueous Solution: Impact on Dissolution Rate

Despite the increasing use of silver nanoparticles (Ag-NPs) in nanotechnology and their toxicity to invertebrates, the transformations and fate of Ag-NPs in the environment are poorly understood. This work focuses on the sulfidation processes of PVP-coated Ag-NPs, one of the most likely corrosion phenomena that may happen in the environment. The sulfur to Ag-NPs ratio was varied in order to control the extent of Ag-NPs transformation to silver sulfide (Ag₂S). A combination of synchrotron-based X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure spectroscopy shows the increasing formation of Ag₂S with an increasing sulfur to Ag-NPs ratio. TEM observations show that Ag₂S forms nanobridges between the Ag-NPs leading to chain-like structures. In addition, sulfidation strongly affects surface properties of the Ag-NPs in terms of surface charge and dissolution rate. Both may affect the reactivity, transport, and toxicity of Ag-NPs in soils. In particular, the decrease of dissolution rate as a function of sulfide exposure may strongly limit Ag-NPs toxicity since released Ag⁺ ions are known to be a major factor in the toxicity of Ag-NPs.

Effect of PVP-coated silver nanoparticles using laser direct patterning process by photothermal effect

Laser direct patterning of silver nanoparticles (AgNPs) conductive patterns on a polyimide substrate using photothermal effect of nanoparticles provides various advantages for applications in flexible electronics. Two PVP content AgNPs were used in this research. Since the thin and thick PVP-coated AgNPs have a strong optical absorption at 426 and 405 nm, respectively, a UV laser (405 nm and 60 mW) is used to trigger AgNPs to convert light into heat due to photothermal effect of nanoparticles. After UV laser beam irradiating on the AgNPs thin film, the AgNPs aggregate into larger conducting grains and improve the adhesion between AgNPs and the polyimide substrate at the same time. Then the desired AgNPs conductive lines (line width: 30 μm, line space: 70 μm) are formed after washing the unirradiated AgNPs. By this method, we have demonstrated a 5 μm width AgNPs conductive line. In the mean time, we also found out that the higher PVP content, the laser direct patterning of AgNPs conductive lines would have more straight and smooth boundaries. And the adhesion between the AgNPs conductive patterns and PI substrate would be better while using higher PVP content AgNPs.

Cytotoxicity and genotoxicity of silver nanoparticles in the human lung cancer cell line, A549

Nanomaterials, especially silver nanoparticles (Ag NPs), are used in a rapidly increasing number of commercial products. Accordingly, the hazards associated with human exposure to nanomaterials should be investigated to facilitate the risk assessment process. A potential route of exposure to NPs is through the respiratory system. In the present study, we investigated the effects of well-characterized PVP-coated Ag NPs and silver ions (Ag+) in the human, alveolar cell line, A549. Dose-dependent cellular toxicity caused by Ag NPs and Ag+ was demonstrated by the MTT and annexin V/propidium iodide assays, and evidence of Ag NP uptake could be measured indirectly by atomic absorption spectroscopy and flow cytometry. The cytotoxicity of both silver compounds was greatly decreased by pretreatment with the antioxidant, N-acetyl-cysteine, and a strong correlation between the levels of reactive oxygen species (ROS) and mitochondrial damage (r(s) = -0.8810; p = 0.0039) or early apoptosis (r(s) = 0.8857; p = 0.0188) was observed. DNA damage induced by ROS was detected as an increase in bulky DNA adducts by (32)P postlabeling after Ag NP exposure. The level of bulky DNA adducts was strongly correlated with the cellular ROS levels (r(s) = 0.8810, p = 0.0039) and could be inhibited by antioxidant pretreatment, suggesting Ag NPs as a mediator of ROS-induced genotoxicity.

Silver nanoparticles up-regulate Connexin43 expression and increase gap junctional intercellular communication in human lung adenocarcinoma cell line A549

Silver nanoparticles (Ag NPs) are increasingly being used in wound dressings, medical settings, and various household products due to their unique properties and antimicrobial activity. Despite the widespread use of Ag NP products, the molecular mechanisms underlying the biological effects of Ag NPs remain unclear. Gap junctional intercellular communication (GJIC), formed by the connexin protein family, plays a critical role in the maintenance of tissue and organ homeostasis. This study was undertaken to investigate the effects of well characterized, PVP-coated Ag NPs (69 ± 3 nm) and silver nitrate on GJIC and connexin43 (Cx43) expression in human lung adenocarcinoma cell line A549. Our results showed that Ag NPs increased GJIC in A549 cells as assayed by dye transfer method. Western blot analysis showed that incubation of cells with Ag NPs significantly increased the expression of Cx43 protein. In addition, Ag NPs up-regulated expression of Cx43 mRNA in a dose-dependent manner. Silver nitrate failed to increase GJIC and the expression of Cx43 protein. It, however, increased Cx43 mRNA expression in A549 cells. Taken together, our results provide the first evidence that Ag NPs induced the increase of GJIC activity in A549 cells through up-regulation of Cx43 protein, suggesting that Cx43 and GJIC may be one of the targets for Ag NPs biological effects.

PVP-coated silver nanoparticles block the transmission of cell-free and cell-associated HIV-1 in human cervical culture

BackgroundPrevious in vitro studies have demonstrated that polyvinylpyrrolidone coated silver nanoparticles (PVP-coated AgNPs) have antiviral activity against HIV-1 at non-cytotoxic concentrations. These particles also demonstrate broad spectrum virucidal activity by preventing the interaction of HIV-1 gp120 and cellular CD4, thereby inhibiting fusion or entry of the virus into the host cell. In this study, we evaluated the antiviral activity of PVP-coated AgNPs as a potential topical vaginal microbicide to prevent transmission of HIV-1 infection using human cervical culture, an in vitro model that simulates in vivo conditions.ResultsWhen formulated into a non-spermicidal gel (Replens) at a concentration of 0.15 mg/mL, PVP-coated AgNPs prevented the transmission of cell-associated HIV-1 and cell-free HIV-1 isolates. Importantly, PVP-coated AgNPs were not toxic to the explant, even when the cervical tissues were exposed continuously to 0.15 mg/mL of PVP-coated AgNPs for 48 h. Only 1 min of PVP-coated AgNPs pretreatment to the explant was required to prevent transmission of HIV-1. Pre-treatment of the cervical explant with 0.15 mg/mL PVP-coated AgNPs for 20 min followed by extensive washing prevented the transmission of HIV-1 in this model for 48 h.ConclusionsA formulation of PVP-coated AgNPs homogenized in Replens gel acts rapidly to inhibit HIV-1 transmission after 1 min and offers long-lasting protection of the cervical tissue from infection for 48 h, with no evidence of cytotoxicity observed in the explants.Based on this data, PVP-coated AgNPs are a promising microbicidal candidate for use in topical vaginal/cervical agents to prevent HIV-1 transmission, and further research is warranted.

PVP-coated silver nanoparticles and silver ions induce reactive oxygen species, apoptosis and necrosis in THP-1 monocytes

The objective of the present study was to investigate the toxicity of silver nanoparticles (Ag NPs) in vitro. Silver ions (Ag+) have been used in medical treatments for decades whereas Ag NPs have been used in a variety of consumer products within recent years. This study was undertaken to compare the effect of well characterized, PVP-coated Ag NPs (69 nm ± 3 nm) and Ag+ in a human monocytic cell line (THP-1). Characterization of the Ag NPs was conducted in both stock suspension and cell media with or without serum and antibiotics. By using the flowcytometric annexin V/propidium iodide (PI) assay, both Ag NPs and Ag+ were shown to induce apoptosis and necrosis in THP-1 cells depending on dose and exposure time. Furthermore, the presence of apoptosis could be confirmed by the TUNEL method. A number of studies have implicated the production of reactive oxygen species (ROS) in cytotoxicity mediated by NPs. We used the fluorogenic probe, 2′,7′-dichlorofluorescein to assess the levels of intracellular ROS during exposure to Ag NPs and Ag+. A drastic increase in ROS levels could be detected after 6–24 h suggesting that oxidative stress is an important mediator of cytotoxicity caused by Ag NPs and Ag+.