Size- and coating-dependent cytotoxicity and genotoxicity of silver nanoparticles evaluated using in vitro standard assays

Silver nanoparticles induce liver inflammation through ferroptosis in zebrafish

As the most widely employed artificial nanomaterials, silver nanoparticles (AgNPs) have been implicated in oxidative stress-induced liver injury. Despite these observations, the precise mechanisms underpinning AgNPs-induced hepatotoxicity have yet to be fully elucidated. This study embarked on an intersectional analysis of the GEO dataset (GSE139560), which encompassed murine liver tissues subjected to AgNPs, alongside datasets related to ferroptosis. Through this approach, three pivotal ferroptosis-associated genes (Arrdc3, Txnip, and Egfr) were identified. Further integration with disease model analysis from GSE111407 and GSE183158 unveiled a significant association between AgNPs exposure and alterations in glucose metabolism and insulin signaling pathways, intricately linked with the identified key ferroptosis genes. This correlation fostered the hypothesis that ferroptosis significantly contributed to the hepatotoxicity triggered by AgNPs. Subsequent Gene Set Enrichment Analysis (GSEA) pointed to the activation of ferroptosis-associated pathways, specifically MAPK and PPAR, under AgNPs exposure. Examination of the miRNA-mRNA interaction network revealed co-regulated upstream miRNAs targeting these pivotal genes, establishing a nexus to ferroptosis and heightened liver susceptibility. Experimental validation employing an adult zebrafish model exposed to AgNPs from 90 to 120 dpf demonstrated elevated levels of Fe2+ and MDA in the zebrafish livers, along with conspicuous mitochondrial morphological alterations, thereby reinforcing the notion that AgNPs precipitate liver dysfunction predominantly through the induction of ferroptosis. These insights collectively underscore the role of ferroptosis in mediating the adverse effects of AgNPs on liver glucose metabolism and insulin sensitivity, culminating in liver dysfunction. Overall, these results enhance the understanding of nanomaterial-induced hepatotoxicity and inform strategies to mitigate such health risks.

The coefficient of conformism of a correlative prediction (CCCP): Building up reliable nano-QSPRs/QSARs for endpoints of nanoparticles in different experimental conditions encoded via quasi-SMILES

Simulation of the physicochemical and biochemical behavior of nanomaterials has its own specifics. However, the main goal of modeling for both traditional substances and nanomaterials is the same. This is an ecologic risk assessment. The universal indicator of toxicity is the n-octanol/water partition coefficient. Mutagenicity indicates the possibility of future undesirable environmental effects, possibly greater than toxicity. Models have been proposed for the octanol/water distribution coefficient of gold nanoparticles and the mutagenicity of silver nanoparticles. Unlike the previous studies, here the models are built using an updated scheme, which includes two improvements. Firstly, the computing involves a new criterion for prediction potential, the so-called coefficient of conformism of a correlative prediction (CCCP); secondly, the Las Vegas algorithm is used to select the potentially most promising models from a group of models obtained by the Monte Carlo algorithm. Apparently, CCCP is a measure of the predictive potential (not only correlation). This can give an advantage in developing a model in comparison to using the classic determination coefficient. Likely, CCCP can be more informative than the classical determination coefficient. The Las Vegas algorithm is able to improve the model obtained by the Monte Carlo method.

Lukianov D, Gayanova TE, Voronova EV, Shishilov ON, Stepakhin VD. The Synthesis and Analysis of the Cytotoxicity of Al2O3-Supported Silver Nanoparticles Prepared by the Plasma Chemical Process Initiated by Pulsed MW Radiation in the Al2O3-Ag Powder Mixtures

An original plasma chemical process initiated by microwave discharge in a mixture of metal and dielectric powders was applied to prepare specific materials, which consisted of microsized spherical particles of aluminum oxide covered with silver nanoparticles. The prepared materials are highly uniform in shape, size distribution, and composition. Their cytotoxicity was investigated using the human cell lines MCF7, HEK293T, A549, and VA-13 and the bacterial strains E. coli JW5503 (ΔtolC) and E. coli K12. Their cytotoxicity was found not to exceed the cytotoxicity of the starting materials. Thus, the prepared materials can be considered highly promising for catalysis and biotechnology applications.

Are hydroxyapatite-based biomaterials free of genotoxicity? A systematic review

Hydroxyapatite (HA) is a biomaterial widely used in clinical applications and pharmaceuticals. The literature on HA-based materials studies is focused on chemical characterization and biocompatibility. Generally, biocompatibility is analyzed through adhesion, proliferation, and differentiation assays. Fewer studies are looking for genotoxic events. Thus, although HA-based biomaterials are widely used as biomedical devices, there is a lack of literature regarding their genotoxicity. This systematic review was carried out following the PRISMA statement. Specific search strategies were developed and performed in four electronic databases (PubMed, Science Direct, Scopus, and Web of Science). The search used "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND genotoxicity OR genotoxic OR DNA damage" and "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND mutagenicity OR mutagenic OR DNA damage" as keywords and articles published from 2000 to 2022, after removing duplicate studies and apply include and exclusion criteria, 53 articles were identified and submitted to a qualitative descriptive analysis. Most of the assays were in vitro and most of the studies did not show genotoxicity. In fact, a protective effect was observed for hydroxyapatites. Only 20 out of 71 tests performed were positive for genotoxicity. However, no point mutation-related mutagenicity was observed. As the genotoxicity of HA-based biomaterials observed was correlated with its nanostructured forms as needles or rods, it is important to follow their effect in chronic exposure to guarantee safe usage in humans.

Human health risk assessment and uncertainty analysis of silver nanoparticles in water

Despite frequent detection in environmental waters, literature which quantifies the health risk of silver nanoparticles (Ag NPs) through oral ingestion is scarce. This study compiled literature data to find the removal of Ag NPs from different treatment schemes (i.e., natural, engineered, or hybrid). Ag NP concentrations were found either in surface water or in groundwater based on where the effluent of treatment schemes was discharged, i.e., either in surface water or in groundwater. Monte-Carlo simulation was carried out for probabilistic assessment of health risks for children for two hypothetical exposure scenarios: (a) ingesting river water while swimming and (b) drinking groundwater. Bio-accessible fraction, dietary metal adsorption factor, and concentrations of silver ions were incorporated to simulate realistic situations. Different treatment schemes were ranked for their nanoparticles' removal efficiency with respect to (i) exceedance probability from guideline value and (ii) health risk to children. Hybrid treatment combinations, i.e., conventional primary and secondary treatment units followed by nature-based units (constructed wetlands and soil aquifer treatment), were ranked the best. The health risk value was found to be less than 1, with the 99th percentile value less than 10-3 in all cases. The maximum allowable concentration of Ag NPs was found to be as low as 1.43 mg/L for groundwater, suggesting probable potential for risk. Uncertainty analysis revealed that the uncertainty of the influent NPs concentration in raw wastewater contributes > 99% to the variance of the hazard index. The results of this work indicate that the use of natural treatment technologies with existing engineered treatments provides higher nanoparticle removal from wastewater without the requirement of any tertiary treatment unit.

Biodistribution and intestinal inflammatory response following voluntary oral intake of silver nanoparticles by C57BL/6J mice

Silver nanoparticles (AgNP) are among the most widely commercialized nanomaterials globally, with applications in medicine and the food industry. Consequently, the increased use of AgNP in the food industry has led to an unavoidable rise  in human exposure to these nanoparticles. Their widespread use raises concerns about potential hazards to human health, specifically their intestinal pro-inflammatory effects. Thus, the main objective of this study was to evaluate the biological effects of two subacute doses of 5 nm polyvinylpyrrolidone (PVP)-AgNP in C57BL/6J mice. One mg/kg body weight or 10 mg/kg bw was provided once a day for 14 days, using a new technology (HaPILLness) that allows voluntary, stress-free, and accurate oral dosing. It was observed that after oral ingestion, while AgNP is biodistributed throughout the entire organism, most of the ingested dose is excreted in the feces. The passage and accumulation of AgNP throughout the intestine instigated a prominent inflammatory response, marked by significant histological, vascular, and cellular transformations. This response was driven by the activation of the nuclear factor-кB (NF-кB) inflammatory pathway, ultimately leading to the generation of multiple cytokines and chemokines.

Functionalization of 3D Printed Scaffolds Using Polydopamine and Silver Nanoparticles for Bone-Interfacing Applications

The prevention of bacterial colonization and the stimulation of osseointegration are two major requirements for bone-interfacing materials to reduce the incidence of complications and promote the restoration of the patient's health. The present investigation developed an effective, two-step functionalization of 3D printed scaffolds intended for bone-interfacing applications using a simple polydopamine (PDA) dip-coating method followed by the formation of silver nanoparticles (AgNPs) after a second coating step in silver nitrate. 3D printed polymeric substrates coated with a ∼20 nm PDA layer and 70 nm diameter AgNPs proved effective in hindering Staphylococcus aureus biofilm formation, with a 3000-8000-fold reduction in the number of bacterial colonies formed. The implementation of porous geometries significantly accelerated osteoblast-like cell growth. Microscopy characterization further elucidated homogeneity, features, and penetration of the coating inside the scaffold. A proof-of-concept coating on titanium substrates attests to the transferability of the method to other materials, broadening the range of applications both in and outside the medical sector. The antibacterial efficiency of the coating is likely to lead to a decrease in the number of bacterial infections developed after surgery in the presence of these coatings on prosthetics, thus translating to a reduction in revision surgeries and improved health outcomes.

ROS generation and p-38 activation contribute to montmorillonite-induced corneal toxicity in vitro and in vivo

BACKGROUND

Montmorillonite (Mt) and its derivatives are now widely used in industrial and biomedical fields. Therefore, safety assessments of these materials are critical to protect human health after exposure; however, studies on the ocular toxicity of Mt are lacking. In particular, varying physicochemical characteristics of Mt may greatly alter their toxicological potential. To explore the effects of such characteristics on the eyes, five types of Mt were investigated in vitro and in vivo for the first time, and their underlying mechanisms studied.

RESULTS

The different types of Mt caused cytotoxicity in human HCEC-B4G12 corneal cells based on analyses of ATP content, lactate dehydrogenase (LDH) leakage, cell morphology, and the distribution of Mt in cells. Among the five Mt types, Na-Mt exhibited the highest cytotoxicity. Notably, Na-Mt and chitosan-modified acidic Na-Mt (C-H-Na-Mt) induced ocular toxicity in vivo, as demonstrated by increases corneal injury area and the number of apoptotic cells. Na-Mt and C-H-Na-Mt also induced reactive oxygen species (ROS) generation in vitro and in vivo, as indicated by 2',7'-dichlorofluorescin diacetate and dihydroethidium staining. In addition, Na-Mt activated the mitogen-activated protein kinase signaling pathway. The pretreatment of HCEC-B4G12 cells with N-acetylcysteine, an ROS scavenger, attenuated the Na-Mt-induced cytotoxicity and suppressed p38 activation, while inhibiting p38 activation with a p38-specific inhibitor decreased Na-Mt-induced cytotoxicity.

CONCLUSIONS

The results indicate that Mt induces corneal toxicity in vitro and in vivo. The physicochemical properties of Mt greatly affect its toxicological potential. Furthermore, ROS generation and p38 activation contribute at least in part to Na-Mt-induced toxicity.

Biological activity of silver nanoparticles synthesized with Paenibacillus polymyxa exopolysaccharides

Recently, there has been increased interest in the synthesis of nanoparticles by using natural polysaccharides. These polysaccharides are eco-friendly, nontoxic, and cheap to prepare. On the other hand, the attention in hydrocolloids and films has significantly enhanced, and their application is very promising in the food, pharmaceutical, perfumery and cosmetics, oil, paper, and textile industries. In this context, the present study is aimed to prepare silver nanoparticles by using viscous and superviscous exopolysaccharides of the rhizobacterium Paenibacillus polymyxa strains, CCM 1465 and 88A, and examined the properties of the resultant nanoparticles. We examined the synthesis and properties of silver nanoparticles under variable synthetic conditions by using exopolysaccharides of the rhizobacteria Paenibacillus polymyxa CCM 1465 and 88A. To prepare nanoparticles, we used different combinations of exopolysaccharide and silver nitrate concentrations: 1-10 mg/mL and 1-40 mM, respectively. The resulting solutions were alkalinized from pH 7.5-12 and heated for 15, 30, and 60 min to determine the optimal synthetic conditions. We found that the exopolysaccharides of strains CCM 1465 and 88A reduced silver ions and acted as nanoparticle stabilizers. The prepared spherical, oval, and triangular particles were stable and ranged in size from 2 to 40 nm, depending on the strain and on the experimental conditions. The nanoparticles showed antibacterial and antifungal activity against Escherichia coli K-12, Pseudomonas aeruginosa 50.3, Bacillus subtilis 26-D, and Fusarium oxysporum. In addition, the nanoparticles were active against SK-MEL-2 human melanoma cells. This finding shows the promise of further research on the exopolysaccharides of P. polymyxa 1465 and 88А in different fields of science, including medicine.

Controllable AgNPs encapsulation to construct biocompatible and antibacterial titanium implant

Silver nanoparticles (AgNPs) are progressively becoming an in-demand material for both medical and life use due to their effective antimicrobial properties. The high surface area-to-volume ratio endows AgNPs with enhanced antibacterial capacity accompanied by inevitable cytotoxicity. Surface coating technique could precisely regulate the particle shape, aggregation, and Ag+ release pattern of AgNPs, by which the cytotoxicity could be significantly reduced. Various coating methods have been explored to shell AgNPs, but it remains a great challenge to precisely control the aggregation state of AgNPs and their shell thickness. Herein, we proposed a simple method to prepare a tunable polydopamine (pDA) coating shell on AgNPs just by tuning the reaction pH and temperature, yet we obtained high antibacterial property and excellent biocompatibility. SEM and TEM revealed that pDA coated AgNPs can form core-shell structures with different aggregation states and shell thickness. Both in vitro and in vivo antibacterial tests show that acid condition and heat-treatment lead to appropriate AgNPs cores and pDA shell structures, which endow Ti with sustained antibacterial properties and preferable cell compatibility. One month of implantation in an infected animal model demonstrated that the obtained surface could promote osteogenesis and inhibit inflammation due to its strong antibacterial properties. Therefore, this study provides a promising approach to fabricate biocompatible antibacterial surface.

A systematic quality evaluation and review of nanomaterial genotoxicity studies: a regulatory perspective

The number of publications in the field of nanogenotoxicology and the amount of genotoxicity data on nanomaterials (NMs) in several databases generated by European Union (EU) funded projects have increased during the last decade. In parallel, large research efforts have contributed to both our understanding of key physico-chemical (PC) parameters regarding NM characterization as well as the limitations of toxicological assays originally designed for soluble chemicals. Hence, it is becoming increasingly clear that not all of these data are reliable or relevant from the regulatory perspective. The aim of this systematic review is to investigate the extent of studies on genotoxicity of NMs that can be considered reliable and relevant by current standards and bring focus to what is needed for a study to be useful from the regulatory point of view. Due to the vast number of studies available, we chose to limit our search to two large groups, which have raised substantial interest in recent years: nanofibers (including nanotubes) and metal-containing nanoparticles. Focusing on peer-reviewed publications, we evaluated the completeness of PC characterization of the tested NMs, documentation of the model system, study design, and results according to the quality assessment approach developed in the EU FP-7 GUIDEnano project. Further, building on recently published recommendations for best practices in nanogenotoxicology research, we created a set of criteria that address assay-specific reliability and relevance for risk assessment purposes. Articles were then reviewed, the qualifying publications discussed, and the most common shortcomings in NM genotoxicity studies highlighted. Moreover, several EU projects under the FP7 and H2020 framework set the aim to collectively feed the information they produced into the eNanoMapper database. As a result, and over the years, the eNanoMapper database has been extended with data of various quality depending on the existing knowledge at the time of entry. These activities are highly relevant since negative results are often not published. Here, we have reviewed the NanoInformaTIX instance under the eNanoMapper database, which hosts data from nine EU initiatives. We evaluated the data quality and the feasibility of use of the data from a regulatory perspective for each experimental entry.

Protective effects of silver nanoparticles in isoproterenol-induced myocardial infarction in rats

Background

Silver nanoparticles (AgNPs) are widely used in the medical field, including cardiovascular. However, limited research has investigated the effect of AgNPs on the protection of myocardial infarction (MI).

Objectives

Isoproterenol (Iso)-induced MI and the cardiac protection offered by AgNPs were investigated in the present study. Additionally, we characterized the profile of Ag in the form of nanoparticles.

Methods

Twenty-four male Wistar rats were randomly divided into four groups as follows: normal, Iso, Iso + AgNO3, and Iso + AgNP groups. AgNPs and silver ion (AgNO3) were administered intraperitoneally at 2.5 mg/kg BW for 14 days. Iso induction was performed using two doses of 85 mg/kg BW given subcutaneously on days 13 and 14. Blood and cardiac tissue samples were taken 24 h after the last dose of Iso and checked for Creatine Kinase-MB (CK-MB), lactate dehydrogenase in plasma along with oxidative stress parameters, mitochondria biogenesis markers, and inflammation representative genes in cardiac tissue. Additionally, we analyzed the histopathological features in cardiac tissue.

Results

The silver was confirmed in the form of nanoparticles by its size at intervals of 8.72-37.84 nm. Both AgNO3 and AgNPs showed similar cardioprotective effects, as shown by the decrease in biochemical markers of cardiac toxicity, namely, CK-MB. Additionally, AgNPs group have better efficacy compared with AgNO3 group in ameliorating Iso-mediated oxidative stress production, as evidenced by the significant decrease in malondialdehyde level and increased superoxide dismutase activity (P < 0.0001 and P < 0.01, respectively) in cardiac tissue compared with the Iso group. Mechanistically, AgNPs, but not AgNO3, enhanced the expression levels of mitochondrial transcription factor A and peroxisome proliferator-activated receptor-gamma coactivator 1-alpha in post-MI heart and reduced the protein expression of nuclear factor-kappa B (NF-κB) assessed by western blot analysis. Furthermore, these results were confirmed with the histopathological evaluation of cardiac tissue. Nevertheless, pretreatment with either AgNO3 or AgNPs improved the aspartate aminotransferase level.

Conclusion

These results suggested that AgNPs have more superior cardioprotective effect compared with AgNO3 against Iso-induced MI, at least in part through amelioration of NF-κB expression level induced by oxidative stress overproduction.

Toxicological Evaluation of Silver Nanoparticles Synthesized with Peel Extract of Stenocereus queretaroensis

Silver nanoparticles (AgNPs) synthesized with plants are widely used in different industries, such as the medical, industrial, and food industries; however, their hazards and risks remain unclear. Here, we aimed to evaluate the toxicological effects of AgNPs in both in vitro and in vivo models. Previously, we developed and characterized green synthesized AgNPs based on Stenocereus queretaroensis (S. queretaroensis). The present study evaluates the toxicity of these AgNPs through cytotoxicity and mutagenicity tests in vitro, as well as genotoxicity tests, including the evaluation of acute oral, dermal, and inhalation toxicity, along with dermal and ocular irritation, in vivo, according to guidelines of The Organization for Economic Co-operation and Development (OECD). We evaluated cell cytotoxicity in L929 cells, and the half-maximal inhibitory concentration was 134.76 µg/mL. AgNPs did not cause genotoxic or mutagenic effects. Furthermore, in vivo oral, dermal, and acute inhalation toxicity results did not show any adverse effects or mortality in the test animals, and after the dermal and ocular irritation assessments, the in vivo models did not exhibit irritation or corrosion. Therefore, the results show that these previously synthesized S. queretaroensis AgNPs do not represent a risk at the tested concentrations; however, little is known about the effects that AgNPs induce on physiological systems or the possible risk following long-term exposure.

Genotoxic potential of different nano-silver halides in cultured human lymphocyte cells

Most antibacterial applications in nanotechnology are carried out using silver nanoparticles (AgNPs). However, there is a dearth of information on the biological effects of AgNPs on human blood cells. In this study, the cytotoxic and genotoxic potentials of ionic silver (Ag⁺), AgNP, silver bromide (AgBr), silver chloride (AgCl), and silver iodide (AgI) were evaluated through chromosome aberration (CA) test and cytokinesis-blocked micronucleus (CBMN) test in human cultured lymphocytes in vitro. Furthermore, the potential damages that can cause to DNA were evaluated through alkaline single cell gel electrophoresis (Comet) assay on isolated lymphocytes. The results showed that AgNPs exerted cytotoxic effects by reducing the cytokinesis-block proliferation index and mitotic index at 24 and 48 h. AgNPs also increased micronucleus (MN) formation at both exposure times in the cultured cells. Meanwhile, AgCl had no genotoxic effects on the human lymphocyte cultured cells but had a cytotoxic effect at high doses. AgNP, Ag⁺, AgBr, and AgI caused substantial DNA damage by forming DNA strand breaks. They may also have clastogenic, genotoxic and cytotoxic effects on human lymphocyte cells. Based on the foregoing findings, silver nanomaterials may have genotoxic and cytotoxic potentials on human peripheral lymphocytes in vitro.

Effects of Particle Size and Surface Charge on Mutagenicity and Chicken Embryonic Toxicity of New Silver Nanoclusters

Though there are many toxicological studies on metal nanoparticles (NPs), it remains difficult to explain discrepancies observed between studies, largely due to the lack of positive controls and disconnection between physicochemical properties of nanomaterials with their toxicities at feasible exposures in a specified test system. In this study, we investigated effects of particle size and surface charge on in vitro mutagenic response and in vivo embryonic toxicity for newly synthesized silver nanoclusters (AgNCs) at human or environmental relevant exposure and compared the new findings with one of the most common nanoscale particles, titanium dioxide NPs (TiO₂ NPs as a positive control). We hypothesized that the interaction of the test system and physicochemical properties of nanomaterials are critical in determining their toxicities at concentrations relevant with human or environmental exposures. We assessed the mutagenicity of the AgNCs (around 2 nm) and two sizes of TiO₂ NPs (i.e., small: 5-15 nm, big: 30-50 nm) using a Salmonella reverse mutation assay (Ames test). The smallest size of AgNCs showed the highest mutagenic activity with the Salmonella strain TA100 in the absence and presence of the S9 mixture, because the AgNCs maintained the nano-size scale in the Ames test, compared with two other NPs. For TiO₂ NPs, the size effect was interfered by the agglomeration of TiO₂ NPs in media and the generation of oxidative stress from the NPs. The embryonic toxicity and the liver oxidative stress were evaluated using a chicken embryo model at three doses (0.03, 0.33, and 3.3 μg/g egg), with adverse effects on chicken embryonic development in both sizes of TiO₂ NPs. The non-monotonic response was determined for developmental toxicity for the tested NPs. Our data on AgNCs was different from previous findings on AgNPs. The chicken embryo results showed some size dependency of nanomaterials, but they were more well correlated with lipid peroxidation (malondialdehyde) in chicken fetal livers. A different level of agglomeration of TiO₂ NPs and AgNCs was observed in the assay media of Ames and chicken embryo tests. These results suggest that the test nanotoxicities are greatly impacted by the experimental conditions and the nanoparticle's size and surface charge.

Cytotoxicity of Metal-Based Nanoparticles: From Mechanisms and Methods of Evaluation to Pathological Manifestations

Metal-based nanoparticles (NPs) are particularly important tools in tissue engineering-, drug carrier-, interventional therapy-, and biobased technologies. However, their complex and varied migration and transformation pathways, as well as their continuous accumulation in closed biological systems, cause various unpredictable toxic effects that threaten human and ecosystem health. Considerable experimental and theoretical efforts have been made toward understanding these cytotoxic effects, though more research on metal-based NPs integrated with clinical medicine is required. This review summarizes the mechanisms and evaluation methods of cytotoxicity and provides an in-depth analysis of the typical effects generated in the nervous, immune, reproductive, and genetic systems. In addition, the challenges and opportunities are discussed to enhance future investigations on safer metal-based NPs for practical commercial adoption.

Does Nanosilver Have a Pronounced Toxic Effect on Humans?

Due to the development of high-tech industries, the modern world is characterized by the increased production and consumption of nanoparticles (NPs) and nanomaterials. Among produced metal nanoparticles, silver nanoparticles are widely used in everyday life products, cosmetics, and medicine. It has already been established that, in nanoscale form, many even inert materials become toxic. Therefore, the study of the toxicity of various substances in nanoscale form is an urgent scientific task. There is now a body of experience on the toxic effect of AgNPs. In the present review, the most well-known results obtained over the 2009–2021 period, including the own performance on the toxicity of silver NPs, are collected and analyzed. Along with the data reporting a certain level of toxicity of silver NPs, experiments that did not reveal any obvious toxicity of nanosized forms of silver are discussed. According to the performed studies, the toxicity of silver NPs is often caused not by NPs themselves but by silver ions, compounds used for nanoparticle stabilization, and other reasons. Based on the analysis of the collected data, it can be concluded that at actual levels of silver NPs used in everyday life, workplace, and medicine, they will not have strong toxic effects on a healthy adult body.

Enhanced wound healing properties of guar gum/curcumin-stabilized silver nanoparticle hydrogels

Biocompatible materials that act as scaffolds for regenerative medicine are of enormous interest. Hydrogel-nanoparticle composites have great potential in this regard, however evaluations of their wound healing and safety in vivo in animal studies are scarce. Here we demonstrate that a guar gum/curcumin-stabilized silver nanoparticle hydrogel composite is an injectable material with exceptional wound healing and antibacterial properties. We show that the curcumin-bound silver nanoparticles themselves exhibit low cytotoxicity and enhance proliferation, migration, and collagen production in in vitro studies of human dermal fibroblasts. We then show that the hydrogel-nanoparticle composite promotes wound healing in in vivo studies on rats, accelerating wound closure by > 40% and reducing bacterial counts by 60% compared to commercial antibacterial gels. Histopathology indicates that the hydrogel composite enhances transition from the inflammation to proliferation stage of healing, promoting the formation of fibroblasts and new blood vessels, while target gene expression studies confirm that the accelerated tissue remodeling occurs along the normal pathways. As such these hydrogel composites show great promise as wound dressing materials with high antibacterial capacity.

Genotoxic Potential of Nanoparticles: Structural and Functional Modifications in DNA

The rapid advancement of nanotechnology enhances the production of different nanoparticles that meet the demand of various fields like biomedical sciences, industrial, material sciences and biotechnology, etc. This technological development increases the chances of nanoparticles exposure to human beings, which can threaten their health. It is well known that various cellular processes (transcription, translation, and replication during cell proliferation, cell cycle, cell differentiation) in which genetic materials (DNA and RNA) are involved play a vital role to maintain any structural and functional modification into it. When nanoparticles come into the vicinity of the cellular system, chances of uptake become high due to their small size. This cellular uptake of nanoparticles enhances its interaction with DNA, leading to structural and functional modification (DNA damage/repair, DNA methylation) into the DNA. These modifications exhibit adverse effects on the cellular system, consequently showing its inadvertent effect on human health. Therefore, in the present study, an attempt has been made to elucidate the genotoxic mechanism of nanoparticles in the context of structural and functional modifications of DNA.

The Action-Networks of Nanosilver: Bridging the Gap between Material and Biology

The emergence of nanosilver (silver in nanoscale shapes and their assemblies) benefits the landscape of modern healthcare; however, this brings about concerns over its safety issues associated with an ultrasmall size and high mobility. By reviewing previous reporting details about the synthesis and characterization of nanosilver and its biological responses, a gap between materials synthesis and their biomedical uses is characterized by the insufficient understanding of the interacting and interplaying nanoscale actions of silver. To improve reporting quality and advance clinical translations, it is suggested that researchers have a comprehensive recognition of the "Indications for use" before designing innovative nanosilver-based materials and an "Action-network" concept addressing the acting range and strength of those nanoscale actions is implemented. Although this discussion is specific to nanosilver, the idea of "Indications for use" centered design and synthesis is generally applicable to other biomedical nanomaterials.

Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells

Purpose

The use of cerium oxide nanoparticles (CeO₂ NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO₂ NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO₂ NPs in human retinal pigment epithelial cells (ARPE-19 cells).

Methods

Using the transmission electron microscope (TEM), the size distribution and shape of CeO₂ NPs were characterized. To explore the effect of CeO₂ NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO₂ NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H₂DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope.

Results

The cytotoxicity of 15 nm CeO₂ NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO₂ NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC).

Conclusion

CeO₂ NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO₂ NP-induced cytotoxicity.

Silver Nanoparticles Derived by Artemisia arborescens Reveal Anticancer and Apoptosis-Inducing Effects

The fight against cancer is one of the main challenges for medical research. Recently, nanotechnology has made significant progress, providing possibilities for developing innovative nanomaterials to overcome the common limitations of current therapies. In this context, silver nanoparticles (AgNPs) represent a promising nano-tool able to offer interesting applications for cancer research. Following this path, we combined the silver proprieties with Artemisia&nbsp;arborescens characteristics, producing novel nanoparticles called Artemisia-AgNPs. A "green" synthesis method was performed to produce Artemisia-AgNPs, using Artemisia&nbsp;arborescens extracts. This kind of photosynthesis is an eco-friendly, inexpensive, and fast approach. Moreover, the bioorganic molecules of plant extracts improved the biocompatibility and efficacy of Artemisia-AgNPs. The Artemisia-AgNPs were fully characterized and tested to compare their effects on various cancer cell lines, in particular HeLa and MCF-7. Artemisia-AgNPs treatment showed dose-dependent growth inhibition of cancer cells. Moreover, we evaluated their impact on the cell cycle, observing a G1 arrest mediated by Artemisia-AgNPs treatment. Using a clonogenic assay after treatment, we observed a complete lack of cell colonies, which demonstrated cell reproducibility death. To have a broader overview on gene expression impact, we performed RNA-sequencing, which demonstrated the potential of Artemisia-AgNPs as a suitable candidate tool in cancer research.

Should Nano-Particles be Weighed or Counted? Technical Considerations to In Vitro Testing Originated from Corpuscular Nature of Nano-Particles

The abundance of nanoparticles introduced to household products created the great expectations towards the application of nanotechnology in biology and medicine. That calls for cost-effective preliminary assessment of its cytotoxicity and biological activity. There are many attempts for creating proper guidance and standards for performing studies regarding nanoparticles. But still some important aspects crucial for in vitro testing of nanomaterials need more attention. Particulate nature is an obvious and widely unappreciated property of nanoparticles. In the context of in vitro studies, this property is critical, and it should be, but rarely is, considered when designing, performing, describing or interpreting the experiments involving the solid nanoparticles. First, we should be aware of relatively small and limited number of nanoparticles in the experimental setup. Even crude estimation of its number will be useful for proper interpretation of results. Second, we should not presume even distribution of particles in the solution, moreover we should expect that sedimentation and aggregation play an important role in interactions of nanoparticles with cells. In that case, expressing the dose in mass/volume units may lead as astray. Finally, the relation of size, weight, and number of nanoparticles makes comparisons of activity of nanoparticles of different sizes very complex. Estimations of number of nanoparticles in the dose should be an integral part of experiment design, its validation and interpretation.

Testing Strategies of the In Vitro Micronucleus Assay for the Genotoxicity Assessment of Nanomaterials in BEAS-2B Cells

The evaluation of the frequency of micronuclei (MN) is a broadly utilised approach in in vitro toxicity testing. Nevertheless, the specific properties of nanomaterials (NMs) give rise to concerns regarding the optimal methodological variants of the MN assay. In bronchial epithelial cells (BEAS-2B), we tested the genotoxicity of five types of NMs (TiO₂: NM101, NM103; SiO₂: NM200; Ag: NM300K, NM302) using four variants of MN protocols, differing in the time of exposure and the application of cytochalasin-B combined with the simultaneous and delayed co-treatment with NMs. Using transmission electron microscopy, we evaluated the impact of cytochalasin-B on the transport of NMs into the cells. To assess the behaviour of NMs in a culture media for individual testing conditions, we used dynamic light scattering measurement. The presence of NMs in the cells, their intracellular aggregation and dispersion properties were comparable when tests with or without cytochalasin-B were performed. The genotoxic potential of various TiO₂ and Ag particles differed (NM101 < NM103 and NM302 < NM300K, respectively). The application of cytochalasin-B tended to increase the percentage of aberrant cells. In conclusion, the comparison of the testing strategies revealed that the level of DNA damage induced by NMs is affected by the selected methodological approach. This fact should be considered in the interpretation of the results of genotoxicity tests.

Silver nanoparticles protect against arsenic induced genotoxicity via attenuating arsenic bioaccumulation and elevating antioxidation in mammalian cells

Arsenic (As) and its compounds have been classified as Group I carcinogenic agents by the International Agency for Research on Cancer (IARC); however, there is few specific and efficient antidotes used for As detoxification. The present study aimed to investigate the protective effects of silver nanoparticles (AgNPs) at non-toxic concentrations on As(Ⅲ) induced genotoxicity and the underlying mechanism. Our data showed that AgNPs pretreatment significantly inhibited the generation of phosphorylated histone H2AX (γ-H2AX, marker of nuclear DNA double strand breaks) and the mutation frequencies induced by As(Ⅲ) exposure. Atomic fluorescence spectrometer (AFS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis revealed that the intracellular accumulation of As(Ⅲ) in human-hamster hybrid A_L cells was declined by AgNPs via suppressing the expression of specific As(Ⅲ)-binding protein (Gal-1). Moreover, the activities of antioxidant enzymes were greatly up-regulated by AgNPs, which eventually inhibited the generation of reactive oxygen species (ROS) induced by As(Ⅲ) and the downstream stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathway. These results provided clear evidence that AgNPs dramatically suppressed the genotoxic response of As(Ⅲ) in mammalian cells via decreasing As(Ⅲ) bioaccumulation and elevating intracellular antioxidation, which might provide a new clue for AgNPs applications in As(Ⅲ) detoxification.

Antitumor Activity against Human Colorectal Adenocarcinoma of Silver Nanoparticles: Influence of [Ag]/[PVP] Ratio

Silver nanoparticles (AgNPs) not only have shown remarkable results as antimicrobial and antiviral agents but also as antitumor agents. This work reports the complete characterization of five polyvinylpyrrolidone-coated AgNP (PVP-AgNP) formulations, their cytotoxic activity against human colon tumor cells (HCT-15), their cytotoxic effect on primary mouse cultures, and their lethal dose on BALB/c mice. The evaluated AgNP formulations have a composition within the ranges Ag: 1.14-1.32% w/w, PVP: 19.6-24.5% and H2O: 74.2-79.2% with predominant spherical shape within an average size range of 16-30 nm according to transmission electron microscopy (TEM). All formulations assessed increase mitochondrial ROS concentration and induce apoptosis as the leading death pathway on HCT-15 cells. Except for AgNP1, the growth inhibition potency of AgNP formulations of human colon tumor cancer cells (HCT-15) is 34.5 times higher than carboplatin, one of the first-line chemotherapy agents. Nevertheless, 5-10% of necrotic events, even at the lower concentration evaluated, were observed. The cytotoxic selectivity was confirmed by evaluating the cytotoxic effect on aorta, spleen, heart, liver, and kidney primary cultures from BALB/c mice. Despite the cytotoxic effects observed in vitro, the lethal dose and histopathological analysis showed the low toxicity of these formulations (all of them on Category 4 of the Globally Harmonized System of Classification and Labelling of Chemicals) and minor damage observed on analyzed organs. The results provide an additional example of the rational design of safety nanomaterials with antitumor potency and urge further experiments to complete the preclinical studies for these AgNP formulations.

Hemolysis of Human Erythrocytes by Argovit™ AgNPs from Healthy and Diabetic Donors: An In Vitro Study

The use of nanomaterials is becoming increasingly widespread, leading to substantial research focused on nanomedicine. Nevertheless, the lack of complete toxicity profiles limits nanomaterials' uses, despite their remarkable diagnostic and therapeutic results on in vitro and in vivo models. Silver nanoparticles (AgNPs), particularly Argovit™, have shown microbicidal, virucidal, and antitumoral effects. Among the first-line toxicity tests is the hemolysis assay. Here, the hemolytic effect of Argovit™ AgNPs on erythrocytes from one healthy donor (HDE) and one diabetic donor (DDE) is evaluated by the hemolysis assay against AgNO3. The results showed that Argovit™, in concentrations ≤24 µg/mL of metallic silver, did not show a hemolytic effect on the HDE or DDE. On the contrary, AgNO3 at the same concentration of silver ions produces more than 10% hemolysis in both the erythrocyte types. In all the experimental conditions assessed, the DDE was shown to be more prone to hemolysis than the HDE elicited by Ag+ ions or AgNPs, but much more evident with Ag+ ions. The results show that Argovit™ is the least hemolytic compared with the other twenty-two AgNP formulations previously reported, probably due to the polymer mass used to stabilize the Argovit™ formulation. The results obtained provide relevant information that contributes to obtaining a comprehensive toxicological profile to design safe and effective AgNP formulations.

A harmonized and standardized in vitro approach produces reliable results on silver nanoparticles toxicity in different cell lines

Despite the widespread use of silver nanoparticles (AgNPs) in different fields and the amount of investigations available, to date, there are many contradictory results on their potential toxicity. In the present study, extensively characterized 20-nm AgNPs were investigated using optimized protocols and standardized methods to test several toxicological endpoints in different cell lines. The agglomeration/aggregation state of AgNPs in culture media was measured by dynamic light scattering (DLS). DNA and chromosomal damage on BEAS-2B and RAW 264.7 cells were evaluated by comet and micronucleus assays, while oxidative DNA damage by modified comet assay and 8-oxodG/8-oxodA detection. We also investigated immunotoxicity and immunomodulation by cytokine release and NO production in RAW 264.7 and MH-S cells, with or without lipopolysaccharide (LPS) stimulus. Transmission electron microscope (TEM) analysis was used to analyze cellular uptake of AgNPs. Our results indicate different values of AgNPs hydrodynamic diameter depending on the medium, some genotoxic effect just on BEAS-2B and no or slight effects on function of RAW 264.7 and MH-S in absence or presence of LPS stimulus. This study highlights the relevance of using optimized protocols and multiple endpoints to analyze the potential toxicity of AgNPs and to obtain reliable and comparable results.

Silver nanoparticles: Correlating particle size and ionic Ag release with cytotoxicity, genotoxicity, and inflammatory responses in human cell lines

The widespread use of silver nanoparticles (AgNPs), their many sources for human exposure, and the ability of AgNPs to enter organisms and induce general toxicological responses have raised concerns regarding their public health and environmental safety. To elucidate the differential toxic effects of polyvinylpyrrolidone-capped AgNPs with different primary particle sizes (i.e. 5, 50, and 75 nm), we performed a battery of cytotoxicity and genotoxicity assays and examined the inflammatory responses in two human cell lines (i.e. HepG2 and A549). Concentration-dependent decreases in cell proliferation and mitochondrial membrane potential and increases in cytokine (i.e. interleukin-6 and interleukin-8) excretion indicated disruption of mitochondrial function and inflammation as the main mediating factors of AgNPs-induced cytotoxicity. An incremental increase in genotoxicity with decreasing AgNPs diameter was noted in HepG2 cells, which was associated with S and G2/M accumulation and transcriptional activation of the GADD45α promoter as reflected by luciferase activity. Dose-related genetic damage, as indicated by Olive tail moment and micronucleus formation, was also observed in A549 cells, but these effects as well as the AgNPs-induced cytotoxicity were more associated with ionic Ag release from nanoparticles (NPs). In summary, the present study addressed different toxicity mechanisms of AgNPs, depending on the cell model, toxicological endpoint, particle size, and degree of Ag+ release from NPs. The results suggest that the GADD45α promoter-driven luciferase reporter cell system provided a rapid screening tool for the identification of genotoxic properties of NPs across a range of different sizes and concentrations.

Mutagenicity of silver nanoparticles evaluated using whole-genome sequencing in mouse lymphoma cells

The increasing medical and food applications of silver nanoparticles (AgNPs) raise concerns about their safety, including the potential health consequences of human exposure. Previous studies found that AgNPs were negative in the Ames test due to both their microbicidal activity and the inability of nanoparticles to penetrate bacterial cell walls. Thus, the mutagenicity of AgNPs is still not completely clear, though they do induce chromosome damage, as suggested by many previous genotoxicity studies. In this study, whole-genome sequencing (WGS) was used to analyze the mutagenicity of AgNPs in mouse lymphoma cells expanded from single-cell clones. The cells were treated with AgNPs, 4-nitroquinolone-1-oxide (4-NQO) as the positive control, and vehicle controls. Both AgNPs and 4-NQO significantly increased mutation frequencies over their concurrent controls by 1.12-fold and 4.89-fold with mutation rates at 4-fold and 130-fold, respectively. AgNP-induced mutations mainly occurred at G:C sites with G:C > T:A transversions, G:C > A:T transitions, and deletions as the most commonly observed mutations. AgNPs also induced higher fold changes in tandem mutations. The results suggest that the WGS mutation assay conducted here can detect the low-level mutagenicity of AgNPs, providing substantial support for the use of the WGS method as a possible alternative assay with respect to the mutagenic assessment of nanomaterials.

Genotoxic Attribute of Bioconjugate of Tyr-AuNps Synthesized by Streptomyces tuirus DBZ39

BACKGROUND AND OBJECTIVE

Nanotechnology is a cumbersome field used in industrial, medical and environmental applications. Abundant information regarding the genotoxicity of gold nanoparticles is available, but limited information is available about the genotoxicity of enzymes and bioconjugates of gold nanoparticles from microbial sources. The present investigation reveals the genotoxicity of bioconjugate of tyrosinase and gold nanoparticles from Streptomyces sp.

MATERIALS AND METHODS

Tyrosinase and gold nanoparticles were isolated from Streptomyces tuirus DBZ39 and employed for the development of bioconjugates by the flocculation assay method. Methyl thiazole (MTT) assay, transmission electron microscopy, Dynamic Light Scattering (DLS) and UV-vis absorption spectroscopy were used for the investigation.

RESULTS

Bioconjugate showed a significant genotoxic effect at a concentration of 18 μL and at least 10 μL. Bioconjugate of tyrosinase and gold nanoparticles by Streptomyces tuirus DBZ39 revealed a more expressed genotoxic effect than nanoparticles alone. The efficacy of gold nanoparticles was expected to improve the bonding of tyrosine due to their catalytic properties.

CONCLUSION

This innovative concept of the application of Tyr-AuNps bioconjugate can be used for the development of powerful weapons in medicinal fields. The introduction of bioconjugates of enzymes and nanoparticles in the field of drug design and cancer imaging will be a fundamental breakthrough in medicine.

New Protein-Coated Silver Nanoparticles: Characterization, Antitumor and Amoebicidal Activity, Antiproliferative Selectivity, Genotoxicity, and Biocompatibility Evaluation

Nanomaterials quickly evolve to produce safe and effective biomedical alternatives, mainly silver nanoparticles (AgNPs). The AgNPs' antibacterial, antiviral, and antitumor properties convert them into a recurrent scaffold to produce new treatment options. This work reported the full characterization of a highly biocompatible protein-coated AgNPs formulation and their selective antitumor and amoebicidal activity. The protein-coated AgNPs formulation exhibits a half-inhibitory concentration (IC₅₀) = 19.7 µM (2.3 µg/mL) that is almost 10 times more potent than carboplatin (first-line chemotherapeutic agent) to inhibit the proliferation of the highly aggressive human adenocarcinoma HCT-15. The main death pathway elicited by AgNPs on HCT-15 is apoptosis, which is probably stimulated by reactive oxygen species (ROS) overproduction on mitochondria. A concentration of 111 µM (600 µg/mL) of metallic silver contained in AgNPs produces neither cytotoxic nor genotoxic damage on human peripheral blood lymphocytes. Thus, the AgNPs formulation evaluated in this work improves both the antiproliferative potency on HCT-15 cultures and cytotoxic selectivity ten times more than carboplatin. A similar mechanism is suggested for the antiproliferative activity observed on HM1-IMSS trophozoites (IC₅₀ = 69.2 µM; 7.4 µg/mL). There is no change in cell viability on mice primary cultures of brain, liver, spleen, and kidney exposed to an AgNPs concentration range from 5.5 µM to 5.5 mM (0.6 to 600 µg/mL). The lethal dose was determined following the OECD guideline 420 for Acute Oral Toxicity Assay, obtaining an LD₅₀ = 2618 mg of Ag/Kg body weight. All mice survived the observational period; the histopathology and biochemical analysis show no differences compared with the negative control group. In summary, all results from toxicological evaluation suggest a Category 5 (practically nontoxic) of the Globally Harmonized System of Classification and Labelling of Chemicals for that protein-coated AgNPs after oral administration for a short period and urge the completion of its preclinical toxicological profile. These findings open new opportunities in the development of selective, safe, and effective AgNPs formulations for the treatment of cancer and parasitic diseases with a significant reduction of side effects.

Correlation intensity index: Building up models for mutagenicity of silver nanoparticles

Nanomaterials become significant component of economics. Consequently, nanomaterials become object of environmental sciences. There is a traditional list of endpoints which are indicators of the ecological risk. Mutagenicity is one of important component in this list. The quasi-SMILES approach, that in contrast to majority of work dedicated to modelling behaviour of nanomaterials gives possibility to consider experimental conditions as well as other circumstances which can impact the behaviour of nanomaterials is suggested. This is carried out via so-called quasi-SMILES. The quasi-SMILES is a line on of codes that contains all the above available eclectic data. Modelling process aimed to build up a model involves Correlation Intensity Index (CII) that is a new criterion of predictive potential of models. The scheme of calculation of CII is described in this work in the first time. The applying of CII together with Index of Ideality Correlation (IIC) in modelling of mutagenicity of silver nanoparticles by the Monte Carlo method using the CORAL software (http://www.insilico.eu/coral) indicates that application of the CII improves the predictive potential of these models for three random splits into the training set (75%) and validation set (25%).

Genotoxicity of Nanomaterials: Advanced In Vitro Models and High Throughput Methods for Human Hazard Assessment-A Review

Changes in the genetic material can lead to serious human health defects, as mutations in somatic cells may cause cancer and can contribute to other chronic diseases. Genotoxic events can appear at both the DNA, chromosomal or (during mitosis) whole genome level. The study of mechanisms leading to genotoxicity is crucially important, as well as the detection of potentially genotoxic compounds. We consider the current state of the art and describe here the main endpoints applied in standard human in vitro models as well as new advanced 3D models that are closer to the in vivo situation. We performed a literature review of in vitro studies published from 2000–2020 (August) dedicated to the genotoxicity of nanomaterials (NMs) in new models. Methods suitable for detection of genotoxicity of NMs will be presented with a focus on advances in miniaturization, organ-on-a-chip and high throughput methods.

Argovit™ Silver Nanoparticles Effects on Allium cepa: Plant Growth Promotion without Cyto Genotoxic Damage

Due to their antibacterial and antiviral effects, silver nanoparticles (AgNP) are one of the most widely used nanomaterials worldwide in various industries, e.g., in textiles, cosmetics and biomedical-related products. Unfortunately, the lack of complete physicochemical characterization and the variety of models used to evaluate its cytotoxic/genotoxic effect make comparison and decision-making regarding their safe use difficult. In this work, we present a systematic study of the cytotoxic and genotoxic activity of the commercially available AgNPs formulation Argovit™ in Allium cepa. The evaluated concentration range, 5-100 µg/mL of metallic silver content (85-1666 µg/mL of complete formulation), is 10-17 times higher than the used for other previously reported polyvinylpyrrolidone (PVP)-AgNP formulations and showed no cytotoxic or genotoxic damage in Allium cepa. Conversely, low concentrations (5 and 10 µg/mL) promote growth without damage to roots or bulbs. Until this work, all the formulations of PVP-AgNP evaluated in Allium cepa regardless of their size, concentration, or the exposure time had shown phytotoxicity. The biological response observed in Allium cepa exposed to Argovit™ is caused by nanoparticles and not by silver ions. The metal/coating agent ratio plays a fundamental role in this response and must be considered within the key physicochemical parameters for the design and manufacture of safer nanomaterials.

Silver nanoparticles: Synthesis, medical applications and biosafety

Silver nanoparticles (AgNPs) have been one of the most attractive nanomaterials in biomedicine due to their unique physicochemical properties. In this paper, we review the state-of-the-art advances of AgNPs in the synthesis methods, medical applications and biosafety of AgNPs. The synthesis methods of AgNPs include physical, chemical and biological routes. AgNPs are mainly used for antimicrobial and anticancer therapy, and also applied in the promotion of wound repair and bone healing, or as the vaccine adjuvant, anti-diabetic agent and biosensors. This review also summarizes the biological action mechanisms of AgNPs, which mainly involve the release of silver ions (Ag+), generation of reactive oxygen species (ROS), destruction of membrane structure. Despite these therapeutic benefits, their biological safety problems such as potential toxicity on cells, tissue, and organs should be paid enough attention. Besides, we briefly introduce a new type of Ag particles smaller than AgNPs, silver Ångstrom (Å, 1 Å = 0.1 nm) particles (AgÅPs), which exhibit better biological activity and lower toxicity compared with AgNPs. Finally, we conclude the current challenges and point out the future development direction of AgNPs.

Cytokinesis-Block Micronucleus Assay Using Human Lymphocytes as a Sensitive Tool for Cytotoxicity/Genotoxicity Evaluation of AgNPs

Silver nanoparticles (AgNPs) are the most used nanomaterials worldwide due to their excellent antibacterial, antiviral, and antitumor activities, among others. However, there is scarce information regarding their genotoxic potential measured using human peripheral blood lymphocytes. In this work, we present the cytotoxic and genotoxic behavior of two commercially available poly(vinylpyrrolidone)-coated silver nanoparticle (PVP-AgNPs) formulations that can be identified as noncytotoxic and nongenotoxic by just evaluating micronuclei (MNi) induction and the mitotic index, but present enormous differences when other parameters such as cytostasis, apoptosis, necrosis, and nuclear damage (nuclear buds (NBUDs) and nucleoplasmic bridges (NPBs)) are analyzed. The results show that Argovit (35 nm PVP-AgNPs) and nanoComposix (50 nm PVP-AgNPs), at concentrations from 0.012 to 12 μg/mL, produce no changes in the nuclear division index (NDI) or micronuclei (MNi) frequency compared with the values found on control cultures of human blood peripheral lymphocytes from a healthy donor. Still, 50 nm PVP-AgNPs significantly decrease the replication index and significantly increase cytostasis, apoptosis, necrosis, and the frequencies of nuclear buds (NBUDs) and nucleoplasmic bridges (NPBs). These results provide evidence that the cytokinesis-block micronucleus (CBMN) assay using human lymphocytes and evaluating the eight parameters provided by the technique is a sensitive, fast, accurate, and inexpensive detection tool to support or discard AgNPs or other nanomaterials, which is worthwhile for continued testing of their effectiveness and toxicity for biomedical applications. In addition, it provides very important information about the role played by the [coating agent]/[metal] ratio in the design of nanomaterials that could reduce adverse effects as much as possible while retaining their therapeutic capabilities.

Development and Application of TK6-derived Cells Expressing Human Cytochrome P450s for Genotoxicity Testing

Metabolism plays a key role in chemical genotoxicity; however, most mammalian cells used for in vitro genotoxicity testing lack effective metabolizing enzymes. We recently developed a battery of TK6-derived cell lines that individually overexpress 1 of 8 cytochrome P450s (CYP1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19, and 3A4) using a lentiviral expression system. The increased expression and metabolic function of each individual CYP in each established cell line were confirmed using real-time PCR, Western blotting, and mass spectrometry analysis; the parental TK6 cells and empty vector (EV) transduced cells had negligible CYP levels. Subsequently, we evaluated these cell lines using 2 prototypical polyaromatic hydrocarbon mutagens, 7,12-dimethylbenz[a]anthracene (DMBA) and benzo[a]pyrene (B[a]P), that require metabolic activation to exert their genotoxicity. DMBA-induced cytotoxicity, phosphorylation of histone H2A.X, and micronucleus formation were significantly increased in TK6 cells with CYP1A1, 1B1, 2B6, and 2C19 expression as compared with EV controls. B[a]P significantly increased cytotoxicity, DNA damage, and chromosomal damage in TK6 cells overexpressing CYP1A1 and 1B1 when compared with EV controls. B[a]P also induced micronucleus formation in TK6 cells expressing CYP1A2. These results suggest that our CYP-expressing TK6 cell system can be used to detect the genotoxicity of compounds requiring metabolic transformation.

Pulmonary toxicity of silver vapours, nanoparticles and fine dusts: A review

Silver is used in a wide range of products, and during their production and use, humans may be exposed through inhalation. Therefore, it is critical to know the concentration levels at which adverse effects may occur. In rodents, inhalation of silver nanoparticles has resulted in increased silver in the lungs, lymph nodes, liver, kidney, spleen, ovaries, and testes. Reported excretion pathways of pulmonary silver are urinary and faecal excretion. Acute effects in humans of the inhalation of silver include lung failure that involved increased heart rate and decreased arterial blood oxygen pressure. Argyria-a blue-grey discoloration of skin due to deposited silver-was observed after pulmonary exposure in 3 individuals; however, the presence of silver in the discolorations was not tested. Argyria after inhalation seems to be less likely than after oral or dermal exposure. Repeated inhalation findings in rodents have shown effects on lung function, pulmonary inflammation, bile duct hyperplasia, and genotoxicity. In our evaluation, the range of NOAEC values was 0.11-0.75 mg/m³. Silver in the ionic form is likely more toxic than in the nanoparticle form but that difference could reflect their different biokinetics. However, silver nanoparticles and ions have a similar pattern of toxicity, probably reflecting that the effect of silver nanoparticles is primarily mediated by released ions. Concerning genotoxicity studies, we evaluated silver to be positive based on studies in mammalian cells in vitro and in vivo when considering various exposure routes. Carcinogenicity data are absent; therefore, no conclusion can be provided on this endpoint.

Genotoxicity of Silver Nanoparticles

Silver nanoparticles (AgNPs) are widely used in diverse sectors such as medicine, food, cosmetics, household items, textiles and electronics. Given the extent of human exposure to AgNPs, information about the toxicological effects of such products is required to ensure their safety. For this reason, we performed a bibliographic review of the genotoxicity studies carried out with AgNPs over the last six years. A total of 43 articles that used well-established standard assays (i.e., in vitro mouse lymphoma assays, in vitro micronucleus tests, in vitro comet assays, in vivo micronucleus tests, in vivo chromosome aberration tests and in vivo comet assays), were selected. The results showed that AgNPs produce genotoxic effects at all DNA damage levels evaluated, in both in vitro and in vivo assays. However, a higher proportion of positive results was obtained in the in vitro studies. Some authors observed that coating and size had an effect on both in vitro and in vivo results. None of the studies included a complete battery of assays, as recommended by ICH and EFSA guidelines, and few of the authors followed OECD guidelines when performing assays. A complete genotoxicological characterization of AgNPs is required for decision-making.

Vapor-Deposited Biointerfaces and Bacteria: An Evolving Conversation

At the biointerface where materials and microorganisms meet, the organic and synthetic worlds merge into a new science that directs the design and safe use of synthetic materials for biological applications. Vapor deposition techniques provide an effective way to control the material properties of these biointerfaces with molecular-level precision that is important for biomaterials to interface with bacteria. In recent years, biointerface research that focuses on bacteria-surface interactions has been primarily driven by the goals of killing bacteria (antimicrobial) and fouling prevention (antifouling). Nevertheless, vapor deposition techniques have the potential to create biointerfaces with features that can manipulate and dictate the behavior of bacteria rather than killing or deterring them. In this review, we focus on recent advances in antimicrobial and antifouling biointerfaces produced through vapor deposition and provide an outlook on opportunities to capitalize on the features of these techniques to find unexplored connections between surface features and microbial behavior.

Surface coatings alter transcriptional responses to silver nanoparticles following oral exposure

Silver nanoparticles (AgNPs) are used in food packaging materials, dental care products and other consumer goods and can result in oral exposure. To determine whether AgNP coatings modulate transcriptional responses to AgNP exposure, we exposed mice orally to 20 nm citrate (cit)-coated AgNPs (cit-AgNPs) or polyvinylpyrrolidone (PVP)-coated AgNPs (PVP-AgNPs) at a 4 mg/kg dose for 7 consecutive days and analyzed changes in the expression of protein-coding genes and long noncoding RNAs (lncRNAs), a new class of regulatory RNAs, in the liver. We identified unique and common expression signatures of protein-coding and lncRNA genes, altered biological processes and signaling pathways, and coding-non-coding gene interactions for cit-AgNPs and PVP-AgNPs. Commonly regulated genes comprised only about 10 and 20 percent of all differentially expressed genes in PVP-AgNP and cit-AgNP exposed mice, respectively. Commonly regulated biological processes included glutathione metabolic process and cellular oxidant detoxification. Commonly regulated pathways included Keap-Nrf2, PPAR, MAPK and IL-6 signaling pathways. The coding-non-coding gene co-expression analysis revealed that protein-coding genes were co-expressed with a variable number of lncRNAs ranging from one to twenty three and may share functional roles with the protein-coding genes. PVP-AgNP exposure induced a more robust transcriptional response than cit-AgNP exposure characterized by more than two-fold higher number of differentially expressed both protein- coding and lncRNA genes. Our data demonstrate that the surface coating strongly modulates the spectrum and the number of differentially expressed genes after oral AgNP exposure. On the other hand, our data suggest that AgNP exposure can alter drug and chemical sensitivity, metabolic homeostasis and cancer risk irrespective of the coating type, warranting further investigations.

The Correlation Contradictions Index (CCI): Building up reliable models of mutagenic potential of silver nanoparticles under different conditions using quasi-SMILES

The interpretation of the mutagenic potential of silver nanoparticles as a mathematical function of (i) dose; (ii) coating; and (iii) type of mutagenicity (TA98 and TA100) gives quantitative models with good statistical quality. So-called quasi-SMILES are used to represent examined objects (silver nanoparticles under different conditions) for building up models. Simplified molecular input-line entry systems (SMILES) is a well-known sequence of symbols for representation of the molecular structure. Quasi-SMILES is a similar sequence of symbols for representation of experimental conditions. The Correlation Contradiction Index (CCI) calculated with data on the calibration set gives possibility to predict quality of correlation of "experimental vs. calculated values of endpoint" for external validation set.

Differential lethal and sublethal effects in embryonic zebrafish exposed to different sizes of silver nanoparticles

Various parameters can influence the toxic response to silver nanoparticles (Ag NPs), including the size and surface properties, as well as the exposure environment and the biological site of action. Herein, we assess the intestinal toxicity of three different sizes (10, 40, and 100 nm) of Ag NPs in embryonic zebrafish, and describe the relationship between the properties and behavior of Ag NPs in the exposure medium, and induction of lethal and sublethal effects. We find that the composition of the medium and the size contribute to differential NPs agglomeration, release of Ag ions, and subsequent effects during exposure. The exposure medium causes dramatic reduction in silver dissolution due to the presence of salts and divalent cations, which limits the lethal potential of silver ions. Lethality is observed primarily for embryos exposed to medium sized Ag NPs (40 nm), but not to the supernatant originated from particles, which suggests that the exposure to particulate silver is the main cause of mortality. On the other hand, the exposure to 10 nm and 100 nm NPs, as well as Ag ions, only causes sublethal developmental defects in skeletal muscles and intestine, and induces a nitric oxide imbalance.