Silver nanoparticles exert toxic effects in human monocytes and macrophages associated with the disruption of Δψm and release of pro-inflammatory cytokines.

Silver nanoparticles (AgNP) are the most widely produced type of nanoparticles due to their antimicrobial and preservative properties. However, their systemic bioavailability may be considered a potential hazard. When AgNP reach the bloodstream, they interact with the immune cells, contributing to the onset and development of an inflammatory response. Monocytes and macrophages play a pivotal role in our defense system, but the interaction of AgNP with these cells is still not clear. Therefore, the main objective of this work was to assess the cytotoxic and pro-inflammatory effects induced by 5, 10, and 50 nm AgNP coated with polyvinylpyrrolidone (PVP) and citrate, in concentrations that could be attained in vivo (0-25 µg/mL), in human monocytes isolated from human blood and human macrophages derived from a monocytic cell line (THP-1). The effects of PVP and citrate-coated AgNP on cell viability, mitochondrial membrane potential, and cytokines release were evaluated. The results evidenced that AgNP exert strong harmful effects in both monocytes and macrophages, through the establishment of a strong pro-inflammatory response that culminates in cell death. The observed effects were dependent on the AgNP concentration, size and coating, being observed more pronounced cytotoxic effects with smaller PVP coated AgNP. The results showed that human monocytes seem to be more sensitive to AgNP exposure than human macrophages. Considering the increased daily use of AgNP, it is imperative to further explore the adverse outcomes and mechanistic pathways leading to AgNP-induced pro-inflammatory effects to deep insight into the molecular mechanism involved in this effect.

Prolonged exposure of human spermatozoa in polyvinylpyrrolidone has detrimental effects on sperm biological characteristics.

Polyvinylpyrrolidone (PVP) has been utilized in intracytoplasmic sperm injection (ICSI) for immobilization and manipulation of spermatozoa. This study aims to determine the suitable time that sperm cells could be safely exposed to PVP during ICSI procedure. Twenty-five normal semen samples were prepared using the swim-up method and then were exposed to 10% PVP at different time intervals (15, 30 and 60 min). The effect of PVP on sperm parameters (viability and morphology), DNA fragmentation index (sperm chromatin dispersion test), chromatin quality (aniline blue, toluidine blue and chromomycin A3 staining), acrosome reaction, mitochondrial membrane potential and sperm ultrastructure was assessed at different time intervals. Our results showed that prolonged sperm exposure in PVP for 15, 30 and 60 min significantly affects viability and morphology with a concomitant increase in DNA fragmentation and abnormal chromatin structure, while the percentage of acrosome-reacted spermatozoa was additionally increased. In addition, the spermatozoa with high mitochondrial membrane potential were significantly decreased compared to unexposed spermatozoa to PVP. In conclusion, the detrimental effects of PVP were increased significantly following sperm exposure in PVP after 15 min. Therefore, the sperm exposure to PVP should be limited to less than 15 min during ICSI procedure.

Preparation of smart PVP/HPMC based IPN hydrogel, its characterization and toxicity evaluation.

In this study, the interpenetrating polymeric network (IPN) were fabricated via free radical polymerization using polymers hydroxypropyl methylcellulose (HPMC), Polyvinylpyrrolidone (PVP) and monomer Methacrylic acid (MAA) and also investigated their influence by changing their concentrations. The developed polymeric network is crosslinked via N' N' -methylene bis-acrylamide (MBA). Different characterizations have been performed to analyze fabricated interpenetrating polymeric network structure i.e., Scanning Electron Microscopy (SEM), X-ray Powder Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Thermo-gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Letrozole (LTZ) was loaded as a model drug in the developed system. Swelling dynamics as well as drug release behavior were thoroughly examined. FTIR studies corroborated the formation of interpenetrating polymeric network. SEM uncovered porous structure while TGA depicted enhanced thermal stability of polymeric network. PXRD depicted amorphous dispersion of LTZ. Swelling dynamics as well as LTZ release behavior from developed interpenetrating polymeric network hydrogels were dependent upon pH of the medium and concentration of pure reactants employed. Higuchi model was best fit to regression coefficient which indicated diffusion controlled mechanism of drug release. Acute oral toxicity study depicted no mortality or any signs relating to acute toxicity throughout the whole observed period. Hence, the designed interpenetrating polymeric network might turn out to be a safe and a potential carrier system for the delivery of LTZ in the treatment of breast cancer (BC).

The toxicity analysis of PVP, PVA and PEG surface functionalized ZnO nanoparticles on embryonic as well as adult Danio rerio.

Globally, the production of zinc oxide nanoparticles (ZnO NPs) increased due to its wide applications including cosmetics, paints etc., and gets accumulated in the environment during their production, use or end-of-life. The toxic effects of the NPs vary with the presence of various surface modification agents. In the current report, toxic effect of bare and capped ZnO NPs with polymeric surface modifying agent including polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) is studied against adult as well as embryonic zebra fish. The surface capped NPs showed great variation in toxicity levels. It was observed that ZnO-PVA showed highly reduced toxic effects relative to ZnO-PEG and ZnO-PVP. Further, various environmental agents including humic acid can also have an impact on NPs toxicity. ZnO particles showed increased toxic effect in humic acid presence. The uptake of ZnO particles by D. rerio was high in the order of PVP-, PEG- and PVA- followed by bare-ZnO. The current investigation found that ZnO NPs dissolution and uptake are the major factors which cause the toxicity against adult as well as embryonic zebra fishes respectively.

Sex affects the response of Wistar rats to polyvinyl pyrrolidone (PVP)-coated silver nanoparticles in an oral 28 days repeated dose toxicity study.

BACKGROUND: Silver nanoparticles (AgNPs) are widely used in biomedicine due to their strong antimicrobial, antifungal, and antiviral activities. Concerns about their possible negative impacts on human and environmental health directed many researchers towards the assessment of the safety and toxicity of AgNPs in both in vitro and in vivo settings. A growing body of scientific information confirms that the biodistribution of AgNPs and their toxic effects vary depending on the particle size, coating, and dose as well as on the route of administration and duration of exposure. This study aimed to clarify the sex-related differences in the outcomes of oral 28 days repeated dose exposure to AgNPs. METHODS: Wistar rats of both sexes were gavaged daily using low doses (0.1 and 1 mg Ag/kg b.w.) of polyvinylpyrrolidone (PVP)-coated small-sized (10 nm) AgNPs. After exposure, blood and organs of all rats were analysed through biodistribution and accumulation of Ag, whereas the state of the liver and kidneys was evaluated by the levels of reactive oxygen species (ROS) and glutathione (GSH), catalase (CAT) activity, superoxide dismutase (SOD) and glutathione peroxidase (GPx), expression of metallothionein (Mt) genes and levels of Mt proteins. RESULTS: In all animals, changes in oxidative stress markers and blood parameters were observed indicating the toxicity of AgNPs applied orally even at low doses. Sex-related differences were noticed in all assessed parameters. While female rats eliminated AgNPs from the liver and kidneys more efficiently than males when treated with low doses, the opposite was observed for animals treated with higher doses of AgNPs. Female Wistar rats exposed to 1 mg PVP-coated AgNPs/kg b.w. accumulated two to three times more silver in the blood, liver, kidney and hearth than males, while the accumulation in most organs of digestive tract was more than ten times higher compared to males. Oxidative stress responses in the organs of males, except the liver of males treated with high doses, were less intense than in the organs of females. However, both Mt genes and Mt protein expression were significantly reduced after treatment in the liver and kidneys of males, while they remained unchanged in females. CONCLUSIONS: Observed toxicity effects of AgNPs in Wistar rats revealed sex-related differences in response to an oral 28 days repeated exposure.

Prussian Blue Nanozymes Prevent Anthracycline-Induced Liver Injury by Attenuating Oxidative Stress and Regulating Inflammation.

Anthracycline-induced liver injury (AILI) is becoming an increasingly serious and potential clinical complication and is linked to reactive oxygen species (ROS) production and subsequent inflammatory response. Herein, we demonstrated that artificial Prussian blue nanozymes (PBZs) prevented daunorubicin-induced liver injury, a prototype of AILI, by attenuating ROS production and regulating inflammation. PBZs exhibited multienzyme activity and could scavenge ROS and free radicals. At the cellular level, PBZs could effectively eliminate ROS, suppress hepatocyte apoptosis, reduce deoxyribonucleic acid damage, and decrease the levels of inflammatory cytokines and chemokines. According to the results of the in vivo study, pretreatment with PBZs also resulted in a desirable protective effect against AILI, as indicated by both a decrease in biochemical indicator levels and hepatocyte necrosis. PBZs upregulated antioxidative genes by activating the Nrf2 pathway to reduce oxidative stress. Meanwhile, PBZs counteracted the inflammatory response based on the decreased expression levels of myeloperoxidase and F4/80 in the liver. Collectively, our findings indicate that PBZ-based nanotherapy is a novel strategy for protecting against AILI.

Environmental stability and cytotoxicity of layered black phosphorus modified with Polyvinylpyrrolidone and Zeolitic Imidazolate Framework-67.

Layered black phosphorus (LBP) is regarded as a promising two-dimensional nanomaterial in various application fields. As bare LBP is unstable in humid environment, many modification methods have been developed recently. However, environmental risks of modified LBP nanomaterials are largely unknown. Herein, by sonication and in-situ surface-confined synthesis, polyvinylpyrrolidone (PVP) coated LBP (LBP/PVP), and zeolitic imidazolate framework-67 (ZIF-67) modified LBP (LBP/PVP-ZIF-67) nanomaterials were synthesized. Environmental stability and toxicity of the modified nanomaterials were compared with bare LBP. Results show that LBP/PVP-ZIF-67 exhibits excellent photothermal performance, and higher potential in electrochemical hydrogen evolution than bare LBP or LBP/PVP. Characteristic visible light absorbance at 593 nm was introduced into the nanomaterial by ZIF-67. LBP/PVP has stability in aqueous environment or cytotoxicity similar to LBP. LBP/PVP-ZIF-67 is completely stable in water within 120 h, in contrast to over 30% degradation of LBP or LBP/PVP. More than 50% of LBP in the LBP/PVP-ZIF-67 can degrade to dissolvable phosphorus in oxygenated water after 17 days, indicating the nanomaterial will not be persistent in the environment. Moreover, modification with ZIF-67 can reduce cytotoxicity of LBP. Therefore, this study develops a safe strategy to modify LBP and provides basic information for ecological risk assessment of LBP based materials.

Neurobehavior and neuron damage following prolonged exposure of silver nanoparticles with/without polyvinylpyrrolidone coating in Caenorhabditis elegans.

Silver nanoparticles (AgNPs) have become widespread in the environment with increasing industrial applications. But the studies about their potential health risks are far from enough, especially in neurotoxic effects. This study aimed to investigate the neurotoxic effects of longer-term exposure (prolonged exposure for 48 h and chronic exposure for 6 days) of 20nm AgNPs with/without polyvinylpyrrolidone (PVP) coating at low concentrations (0.01-10 mg·L-1 ) to Caenorhabditis elegans. The results suggested that exposure to AgNPs induced damage to nematode survival, with the longest and relative average life span reduced. Exposure to AgNPs caused neurotoxicity on locomotion behaviors (head thrashes, body bends, pharyngeal pumping frequency, and defecation interval) and sensory perception behaviors (chemotaxis assay and thermotaxis assay), as well as impaired dopaminergic, GABAergic, and cholinergic neurons, except for glutamatergic, based on the alters fluorescence intensity, in a dose- and time-dependent manner. Further investigations suggested that the low-dose AgNPs (0.01-0.1 mg·L-1 ) exposure raises receptors of GABAergic and dopamine in C. elegans at the genetic level, whereas opposite results were observed at higher doses (1-10 mg·L-1 ), which implied that AgNPs could cause neurotoxicity by impairing neurotransmitter delivery. The PVP-AgNPs could cause a higher fatality rate and neurotoxicity at the same dose. Notably, AgNPs did not cause any deleterious effect on nematodes at the lowest dose of 0.01 mg·L-1 . In general, these results suggested that AgNPs possess the neurotoxic potential in C. elegans and provided useful information to understand the neurotoxicity of AgNPs, which would offer an inspiring perspective on the safe application.

MOF-derived novel porous Fe3O4@C nanocomposites as smart nanomedical platforms for combined cancer therapy: magnetic-triggered synergistic hyperthermia and chemotherapy.

Multifunctional nanomedical platforms have broad prospects in imaging-guided combination therapy in cancer precision medicine. In this work, metal-organic framework (MOF)-derived novel porous Fe3O4@C nanocomposites were developed as an intelligent cancer nanomedical platform for combined cancer therapy with MRI-guided magnetic-triggered hyperthermia and chemotherapy functions. The magnetic behavior, porous character and good surface modification endowed this smart nanoplatform with favorable biocompatibility, high-efficiency MRI imaging, magnetic-triggered on-demand DOX release function, and synergistic therapy of magnetic hyperthermia and chemotherapy, which proposed an all-in-one platform for cancer therapy. Additionally, in vivo animal experiments verified the significant suppression of malignant tumor growth with negligible side effects, which were attributed to the consecutive 13 day synergistic therapy of magnetic hyperthermia and chemotherapy in one. To be specific, Fe3O4@C-PVP@DOX significantly decreases the volume (2.5 to 0.44 of tumor volume ratio) and weight (0.49 g to 0.10 g) of tumors after magnetic-triggered hyperthermia and chemotherapy treatments. Moreover, no big difference of body weight and associated damage was observed among all major organs. Therefore, owing to its high-efficiency combined therapy of magnetic-triggered hyperthermia and chemotherapy, this smart nanoplatform holds great potential application in the precise treatments of clinical cancer.

Comparative study of cytotoxicity by platinum nanoparticles and ions in vitro systems based on fish cell lines.

Emission of platinum nanoparticles (Pt NPs) especially from vehicle exhaust catalysts and pharmaceutics cause an increase in concentrations of this metal in aquatic environments. In this study, small (4-9 nm) uncoated and polyvinylpyrrolidone (PVP) coated Pt NPs were synthetized and their dispersion in different exposure media were evaluated. Pt NP uptake in two established fish cell lines were investigated and comparative in vitro cytotoxicity of Pt NPs and ions were assessed. The coated and uncoated Pt NPs dispersions in minimum essential medium (MEM) with fetal bovine serum (FBS) displayed high colloidal stability. Transmission electron microscopy (TEM) and high-resolution scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (STEM/EDX) indicated no detectable cellular uptake of Pt NPs in both cell line monolayers. But with ICP-MS analysis, trace amount of Pt content was determined in all digested monolayer cell samples. The cytotoxicity of both Pt NPs and Pt ions on both fish cell lines after 48 h exposure was investigated through three assays to monitor different endpoints of cytotoxicity. In all studied concentrations (0.325-200 mg/L) no significant cytotoxicity (p > .5) compared to controls were observed in the cells exposed to coated Pt NPs. Uncoated Pt NP and ion exposed cells indicated similar concentration dependent cytotoxicity on both cell lines.

Biodistribution and organ oxidative damage following 28 days oral administration of nanosilver with/without coating in mice.

This study evaluated the biodistribution and organ oxidative effects of silver nanoparticles (AgNPs) coated with/without polyvinylpyrrolidone (PVP) (AgNP-20 and AgNP-PVP) in mice; these were administered by gavage at a dose of 10-250 mg/kg body weight per day for 28 days. The results showed that both the AgNPs could induce subacute toxicity and oxidative damage to mice and were mainly accumulated in the liver and spleen and excreted by feces. AgNPs could be absorbed into blood and might cross the blood-brain barrier, and be distributed extensively in mice. The malondialdehyde content in the liver, lungs and kidneys increased in both AgNP groups, while the content of glutathione decreased, and the activity of superoxide dismutase increased at first and then decreased along with the increased doses. Inflammatory pathological changes in the lung and liver at high dose of both AgNPs were consistent with increases in glutamate pyruvic transaminase, glutamate oxaloacetic transaminase and the total protein in serum detection. The Ag content was detected in organs, with the highest content in the liver, followed by spleen, while the Ag content in feces was about 500 times higher than that in urine. AgNP-PVP could induce higher oxidative stress and subacute toxicity than AgNP-20 at the same dose, which might be related to the higher concentrations and more Ag+ ions released in mice after AgNP-PVP exposure. The data from this research provided information on toxicity and biodistribution of AgNPs following gavage administration in mice, and might shed light for future application of AgNPs in daily life.

Neurotoxicity of silver nanoparticles stabilized with different coating agents: In vitro response of neuronal precursor cells.

Silver nanoparticles (AgNPs) represent one of the most abundant biocidal nanomaterials contained in more than 30% of nano-enabled consumer products and 75% of nanomedical products. The cumulative exposure of the general population may therefore reach critical and potentially hazardous levels. Due to data gaps on AgNP effects in humans, it is urgent to further evaluate their possible toxicity, particularly in vulnerable systems like the nervous one. As AgNPs may cross the blood brain and placental barriers, this study evaluated the in vitro effect of different AgNPs on neuronal precursor cells. For this purpose, 10 nm-sized AgNPs were stabilized with five different coating agents rendering a neutral, positive and negative surface charge. Murine neural stem cells (mNSCs) were used as cellular model to test AgNP neurotoxicity by evaluating the range of toxicity endpoints including cellular viability, apoptosis induction, oxidative stress response, cellular and mitochondrial membrane damages, DNA damage, inflammation response, and neural stem cell regulation. Our results clearly showed that the neurotoxic potential of AgNPs was not dependent on their surface charge or coating agents used for their surface stabilization. All AgNP types exhibited significant toxicity in neuronal precursor cells at an in vitro dose of 5 mg Ag/L or lower.

The influence of surface coatings on the toxicity of silver nanoparticle in rainbow trout.

Silver nanoparticles (nAg) are often produced with different coatings that could influence bioavailability and toxicity in aquatic organisms. The purpose of this study was to examine the influence of 4 surface coatings of nAg of the same core size towards bioavailability and toxicity in juvenile rainbow trout (Oncorhynchus mykiss). Juveniles were exposed to 50 µg/L of 50 nm diameter nAg for 96 h at 15 °C with the following coatings: branched polyethylenimine (bPEI), citrate, polyvinylpyrrolidone (PVP) and silicate (Si). The data revealed that the coatings influenced hepatic Ag loadings in the following trend PVP > citrate > bPEI and Si with estimated bioavailability factors of 28, 18, 6 and 2 L/kg respectively. Hepatic Ag levels were significantly associated with DNA damage and inflammation as determined by arachidonate cyclooxygenase activity. The bPEI and citrate-coated nAg consistently produced the observed effects above in addition to increased mitochondrial electron transport activity and glutathione S-transferase activity. The absence of metallothionein and lipid peroxidation suggests that mechanisms other than the liberation of Ag+ were at play. In conclusion, surface coatings were shown to significantly influence bioavailability and toxic properties of nAg to rainbow trout juveniles.

Enhanced cancer therapy with pH-dependent and aptamer functionalized doxorubicin loaded polymeric (poly D, L-lactic-co-glycolic acid) nanoparticles.

Aptamer based drug delivery systems are gaining the importance in anticancer therapy due to their targeted drug delivery efficiency without harming the normal cells. The present work formulated the pH-dependent aptamer functionalized polymer-based drug delivery system against human lung cancer. The prepared aptamer functionalized doxorubicin (DOX) loaded poly (D, L-lactic-co-glycolic acid) (PLGA), poly (N-vinylpyrrolidone) (PVP) nanoparticles (APT-DOX-PLGA-PVP NPs) were spherical in shape with an average size of 87.168 nm. The crystallography and presence of the PLGA (poly (D, L-lactic-co-glycolic acid)) and DOX (doxorubicin) in APT-DOX-PLGA-PVP NPs were indicated by the X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and 1H and 13C nuclear magnetic resonance spectrometer (NMR). The pH-dependent aptamer AS1411 based drug release triggered the cancer cell death was evidenced by cytotoxicity assay, flow cytometry, and fluorescent microscopic imaging. In addition, the cellular uptake of the DOX was determined and the apoptosis-related signaling pathway in the A549 cells was studied by Western blot analysis. Further, the in vivo study revealed that mice treated with APT-DOX-PLGA-PVP NPs were significantly recovered from cancer as evident by mice weight and tumor size followed by the histopathological study. It was reported that the APT-DOX-PLGA-PVP NPs induced the apoptosis through the activation of the apoptosis-related proteins. Hence, the present study revealed that the APT-DOX-PLGA-PVP NPs improved the therapeutic efficiency through the nucleolin receptor endocytosis targeted drug release.

Translocation, biotransformation-related degradation, and toxicity assessment of polyvinylpyrrolidone-modified 2H-phase nano-MoS2.

Nano-MoS2 has been extensively investigated in materials science and biomedicine. However, the effects of different methods of exposure on their translocation, biosafety, and biotransformation-related degradability remain unclear. In this study, we combined the advantages of synchrotron radiation (SR) X-ray absorption near-edge structure (XANES) and high-resolution single-cell SR transmission X-ray microscopy (SR-TXM) with traditional analytical techniques to investigate translocation, precise degraded species/ratio, and correlation between the degradation and toxicity levels of polyvinylpyrrolidone-modified 2H-phase MoS2 nanosheets (MoS2-PVP NSs). These NSs demonstrated different biodegradability levels in biomicroenvironments with H2O2, catalase, and human myeloperoxidase (hMPO) (H2O2 < catalase < hMPO). The effects of NSs and their biodegraded byproducts on cell viability and 3D translocation at the single-cell level were also assessed. Toxicity and translocation in mice via intravenous (i.v.), intraperitoneal (i.p.), and intragastric (i.g.) administration routes guided by fluorescence (FL) imaging were investigated within the tested dosage. After i.g. administration, NSs accumulated in the gastrointestinal organs and were excreted from feces within 48 h. After i.v. injection, NSs showed noticeable clearance due to their decreased accumulation in the liver and spleen within 30 days when compared with that in the i.p. group, which exhibited slight accumulation in the spleen. This work paves the way for understanding the biological behaviors of nano-MoS2 using SR techniques that provide more opportunities for future applications.

Pulmonary exposure to silver nanoparticles impairs cardiovascular homeostasis: Effects of coating, dose and time.

Pulmonary exposure to silver nanoparticles (AgNPs) revealed the potential of nanoparticles to cause pulmonary toxicity, cross the alveolar-capillary barrier, and distribute to remote organs. However, the mechanism underlying the effects of AgNPs on the cardiovascular system remains unclear. Hence, we investigated the cardiovascular mechanisms of pulmonary exposure to AgNPs (10 nm) with varying coatings [polyvinylpyrrolidone (PVP) and citrate (CT)], concentrations (0.05, 0.5 and 5 mg/kg body weight), and time points (1 and 7 days) in BALB/C mice. Silver ions (Ag+) were used as ionic control. Exposure to AgNPs induced lung inflammation. In heart, tumor necrosis factor α, interleukin 6, total antioxidants, reduced glutathione and 8-isoprostane significantly increased for both AgNPs. Moreover, AgNPs caused oxidative DNA damage and apoptosis in the heart. The plasma concentration of fibrinogen, plasminogen activation inhibitor-1 and brain natriuretic peptide were significantly increased for both coating AgNPs. Likewise, the prothrombin time and activated partial thromboplastin time were significantly decreased. Additionally, the PVP- and CT- AgNPs induced a significant dose-dependent increase in thrombotic occlusion time in cerebral microvessels at both time points. In vitro study on mice whole blood exhibited significant platelet aggregation for both particle types. Compared with AgNPs, Ag+ increased thrombogenicity and markers of oxidative stress, but did not induce either DNA damage or apoptosis in the heart. In conclusion, pulmonary exposure to AgNPs caused cardiac oxidative stress, DNA damage and apoptosis, alteration of coagulation markers and thrombosis. Our findings provide a novel mechanistic insight into the cardiovascular pathophysiological effects of lung exposure to AgNPs.

Size- and shape-dependent toxicity of silver nanomaterials in green alga Chlorococcum infusionum.

Silver nanomaterials (AgNMs) of different shapes and sizes are potentially toxic to aquatic organisms. However, studies on the toxicity of AgNMs and on their shape-dependent effects on algae are scarce. The present study evaluated the effects of three AgNMs (silver nanospheres, AgNPs; silver nanowires, AgNWs; silver nanoplates, AgPLs) with different shapes coated with polyvinylpyrrolidone on the growth and photosynthetic performance of an alga, Chlorococcum infusionum. We used growth measurements and determined the photosynthetic parameters based on chlorophyll fluorescence transients in the algal cells exposed to different concentrations of the three AgNMs. The effective concentrations at 50% (EC50) of AgNPs, AgNWs, and AgPLs were calculated to be 0.1, 0.045, and 0.021 mg/L, respectively. The results showed that the toxicity of AgNMs in C. infusionum was in the order, AgPLs (40 nm diameter) > AgNWs (21,000 nm length × 42 nm diameter) > AgNPs (57 nm diameter), based on the decrease in growth and three photosynthetic activities. We propose that the toxic potential of AgNMs is primarily dependent on their diameter and secondarily on their shape. Overall, this study provides, for the first time, a comparison of the growth and photosynthetic activities of C. infusionum exposed to AgNMs of three different shapes.

Toxicity responses of different organs of zebrafish (Danio rerio) to silver nanoparticles with different particle sizes and surface coatings.

Silver nanoparticles (AgNPs) in aquatic ecosystems are toxic to aquatic organisms. In this study, we aimed to investigate the toxicities and molecular mechanisms of AgNPs with different surface coatings (sodium citrate and polyvinylpyrrolidone) and particle sizes (20 nm and 100 nm) in the gills, intestines, and muscles of zebrafish after 96 h of exposure. Our results indicated that the contribution of particle size to AgNP toxicity was greater than that of the surface coating. Citrate-coated AgNPs were more toxic than polyvinylpyrrolidone-coated AgNPs, and 20-nm AgNPs were more toxic than 100-nm AgNPs. The toxic effects of AgNPs to the tissues were in the order intestines > gills > muscles. Differential expression of genes with the different AgNPs confirmed that they had toxic effects in the zebrafish tissues at the molecular level. Our comprehensive comparison of the toxicities of different AgNPs to aquatic ecosystems will be helpful for further risk assessments of AgNPs.

Using primary organotypic mouse midbrain cultures to examine developmental neurotoxicity of silver nanoparticles across two genetic strains.

Micromass culture systems have been developed as three-dimensional organotypic in vitro alternatives to test developmental toxicity. We have optimized a murine-based embryonic midbrain micromass system in two genetic strains to evaluate neurodevelopmental effects of gold-cored silver nanoparticles (AgNPs) of differing sizes and coatings-20 nm AgCitrate, 110 nm AgCitrate, and 110 nm AgPVP. AgNPs are increasingly used in consumer, commercial, and medical products for their antimicrobial properties and observations of Ag in adult and fetal brain following in vivo exposures to AgNPs have led to concerns about the potential for AgNPs to elicit adverse effects on neurodevelopment and neurological function. Cytotoxicity was assessed at three time points of development by both nominal dose and by dosimetric dose. Ag dosimetry was assessed in cultures and the gold core component of the AgNPs was used as a tracer for determination of uptake of intact AgNPs and silver dissolution from particles in the culture system. Results by both nominal and dosimetric dose show cell death increased significantly in a dose-dependent manner at later time points (days 15 and 22 in vitro) that coincide with differentiation stages of development in both strains. When assessed by dosimetric dose, cultures were more sensitive to smaller particles, despite less uptake of Ag in smaller particles in both strains.

Comparative cytotoxicity and apoptotic pathways induced by nanosilver in human liver HepG2 and L02 cells.

Silver nanoparticles are used in many commercial products in daily life. Exposure to nanosilver has hepatotoxic effects in animals. This study investigated the cytotoxicity associated with polyvinylpyrrolidone-coated nanosilver (23.44 ± 4.92 nm in diameter) exposure in the human hepatoma cell line (HepG2) and normal hepatic cell line (L02), and the molecular mechanisms induced by nanosilver in HepG2 cells. Nanosilver, in doses of 20-160 µg mL-1 for 24 and 48 h, reduced cell viability in a dose- and time-dependent manner and induced cell membrane leakage and mitochondria injury in both cell lines; these effects were more pronounced in HepG2 cells than in L02 cells. Intracellular oxidative stress was documented by reactive oxygen species (ROS) being generated in HepG2 cells but not in L02 cells, an effect possibly due to differential uptake of nanosilver by cancer cells and normal cells. In HepG2 cells, apoptosis was documented by finding that ROS triggered a decrease in mitochondrial membrane potential, an increase in cytochrome c release, activation of caspase 3 and caspase 9, and a decrease in the ratio of Bcl-2/Bax. Furthermore, nanosilver activated the Fas death receptor pathway by downregulation of nuclear factor-κB and activation of caspase 8 and caspase 3. These results suggest that apoptosis induced by nanosilver in HepG2 cells is mediated via a mitochondria-dependent pathway and the Fas death receptor pathway. These findings provide toxicological and mechanistic information that can help in assessing the effects of nanosilver in biological systems, including the potential for anticancer activities.