Silver nanoparticles induced neurotoxicity through oxidative stress in rat cerebral astrocytes is distinct from the effects of silver ions

Emerging contaminants: A One Health perspective

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN's Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

AhR Agonistic Components in Urban Particulate Matter Regulate Astrocytic Activation and Function

Exposure to atmospheric particulate matter (PM) has been found to accelerate the onset of neurological disorders via the induction of detrimental neuroinflammatory responses. To reveal how astrocytes respond to urban atmospheric PM stimulation, a commercially available standard reference material (SRM1648a) was tested in this study on the activation of rat cortical astrocytes. The results showed that SRM1648a stimulation induced both A1 and A2 phenotypes in astrocytes, as characterized by the exposure concentration-dependent increases in Fkbp5, Sphk1, S100a10, and Il6 mRNA levels. Studying the functional alterations of astrocytes indicated that the neurotrophic factors of Gdnf and Ngf were transcriptionally upregulated due to astrocytic A2-type activation. SRM1648a also promoted autonomous motility of astrocytes and elevated the expressions of chemokines. The aryl hydrocarbon receptor (AhR) agonistic components, such as polycyclic aromatic hydrocarbons (PAHs), were recognized to greatly contribute to SRM1648a-induced effects on astrocytes, which was confirmed by the attenuation of PM-disturbed astrocytic effects via AhR blockage. This study, for the first time, uncovered the direct regulation of urban atmospheric PM on astrocytic activation and function and traced the containing bioactive components (e.g., PAHs) with AhR agonistic activity. The findings provided new knowledge on understanding the ambiguous neurological disturbance from ambient fine PM pollution.

Silver nanoparticle ecotoxicity and phytoremediation: a critical review of current research and future prospects

Silver nanoparticles (AgNPs) are widely used in various industries, including textiles, electronics, and biomedical fields, due to their unique optical, electronic, and antimicrobial properties. However, the extensive use of AgNPs has raised concerns about their potential ecotoxicity and adverse effects on the environment. AgNPs can enter the environment through different pathways, such as wastewater, surface runoff, and soil application and can interact with living organisms through adsorption, ingestion, and accumulation, causing toxicity and harm. The small size, high surface area-to-volume ratio, and ability to generate reactive oxygen species (ROS) make AgNPs particularly toxic. Various bioremediation strategies, such as phytoremediation, have been proposed to mitigate the toxic effects of AgNPs and minimize their impact on the environment. Further research is needed to improve these strategies and ensure their safety and efficacy in different environmental settings.

Bioinspired silver nanoparticle-based nanocomposites for effective control of plant pathogens: A review

Plant pathogens, including bacteria, fungi, and viruses, pose significant challenges to the farming community due to their extensive diversity, the rapidly evolving phenomenon of multi-drug resistance (MDR), and the limited availability of effective control measures. Amid mounting global pressure, particularly from the World Health Organization, to limit the use of antibiotics in agriculture and livestock management, there is increasing consideration of engineered nanomaterials (ENMs) as promising alternatives for antimicrobial applications. Studies focusing on the application of ENMs in the fight against MDR pathogens are receiving increasing attention, driven by significant losses in agriculture and critical knowledge gaps in this crucial field. In this review, we explore the potential contributions of silver nanoparticles (AgNPs) and their nanocomposites in combating plant diseases, within the emerging interdisciplinary arena of nano-phytopathology. AgNPs and their nanocomposites are increasingly acknowledged as promising countermeasures against plant pathogens, owing to their unique physicochemical characteristics and inherent antimicrobial properties. This review explores recent advancements in engineered nanocomposites, highlights their diverse mechanisms for pathogen control, and draws attention to their potential in antibacterial, antifungal, and antiviral applications. In the discussion, we briefly address three crucial dimensions of combating plant pathogens: green synthesis approaches, toxicity-environmental concerns, and factors influencing antimicrobial efficacy. Finally, we outline recent advancements, existing challenges, and prospects in scholarly research to facilitate the integration of nanotechnology across interdisciplinary fields for more effective treatment and prevention of plant diseases.

Nanotechnology-based Nose-to-brain Delivery in Epilepsy: A NovelApproach to Diagnosis and Treatment

Epilepsy is a serious neurological disease, and scientists have a significant challenge in developing a noninvasive treatment for the treatment of epilepsy. The goal is to provide novel ideas for improving existing and future anti-epileptic medications. The injection of nano treatment via the nose to the brain is being considered as a possible seizure control method. Various nasal medicine nanoformulations have the potential to cure epilepsy. Investigations with a variety of nose-to-brain dosing methods for epilepsy treatment have yielded promising results. After examining global literature on nanotechnology and studies, the authors propose nasal administration with nanoformulations as a means to successfully treat epilepsy. The goal of this review is to look at the innovative application of nanomedicine for epilepsy treatment via nose-to-brain transfer, with a focus on the use of nanoparticles for load medicines. When nanotechnology is combined with the nose to brain approach, treatment efficacy can be improved through site specific delivery. Furthermore, this technique of administration decreases adverse effects and patient noncompliance encountered with more traditional procedures.

Nanoplastics induce neuroexcitatory symptoms in zebrafish (Danio rerio) larvae through a manner contrary to Parkinsonian's way in proteomics

Although nanoplastics (NPs) can penetrate the blood-brain barrier and accumulate in the brain, the neurotoxicity of these particles and the mechanisms associated with their unique physio-chemical properties have yet to be sufficiently ascertained. In this study, we assessed the neuroexcitatory symptoms of zebrafish (Danio rerio) larvae treated with polystyrene (PS) NPs based on an examination of locomotory behaviour, dopamine levels, and acetylcholinesterase activity. We found that PS NPs caused oxidative stress and inhibited atoh1a expression in the cerebellum of Tg(atoh1a:dTomato) transgenic zebrafish larvae, thereby indicating damage to the central nervous system. In contrast to the Parkinson's disease (PD) like effects induced by most types of nanoparticles, such as graphene oxide, we established that PS NPs influenced the neuronal proteomic profiles of zebrafish larvae in a manner contrary to the molecular pathways characteristic of PD-like effects, which could be explained by the molecular dynamic simulation. Unlike graphene oxide nanoparticles that promote significant change in the internal structure of neuroproteins, the complex macromolecular polymers of PS NPs promoted the coalescence and increased expression of neuroproteins, thereby plausibly contributing to the neuroexcitatory symptoms observed in treated zebrafish larvae. Consequently, compared with traditional nanoparticles, we believe that the unique physio-chemical properties of NPs could be a potential factor contributing to their toxicity.

Lycopene attenuates silver nanoparticle-induced liver injury in albino mice

Lycopene is a carotenoid widely used for its dominant antioxidant properties and beneficial health effects. Silver nanoparticles (AgNP) have gained attention for use in many medicinal and consumer products, leading to animal, human, and environmental exposure. This study investigated the dose-dependent effects of lycopene on AgNP-induced hepatotoxicity in albino mice. The four experimental groups, comprising eight albino mice each, were as follows: Group I, vehicle control (C); Group II, AgNP-treated (5 mg/kg/day) (AgNP); Group III, AgNP/lycopene-treated (5 + 10 mg/kg/day) (AgNP + LP10); and Group IV, AgNP/lycopene-treated (5 + 100 mg/kg/day) (AgNP + LP100). All solutions were orally administered to the mice once in a day for consecutive 14 days. The levels of serum aspartate transaminase, alanine transaminase, alkaline phosphatase, and total bilirubin were significantly higher in the AgNP-treated group than in the control group but significantly lower in the AgNP + LP100 group than in the AgNP-treated group. A significant decrease in reduced glutathione level and superoxide dismutase activity and an increase in lipid peroxidation were observed in the AgNP-treated group; these were significantly suppressed in the AgNP+LP100 as compared to AgNP-treated group. Histopathological examination showed substantial morphological alterations in hepatic tissues in the AgNP, which were adequately improved in the low and high dose lycopene-treated groups. The dose of 100 mg/kg/day of lycopene was more effective than 10 mg/kg/day, as pretreatment with high dose lycopene significantly diminished the adverse changes occurred due to AgNP in liver weight, hepatic architecture, serum functional markers, and antioxidant markers. Thus, present study shows that pretreatment with lycopene offers protection against AgNP-induced hepatotoxicity and oxidative stress.

Long-term application of silver nanoparticles in dental restoration materials: potential toxic injury to the CNS

Silver nanoparticles (AgNPs) have durable and remarkable antimicrobial effects on pathogenic microorganisms, such as bacteria and fungi, in dental plaques. As such, they are widely added to dental restoration materials, including composite resins, denture bases, adhesives, and implants, to solve the problems of denture stomatitis, peri-implant inflammation, and oral infection caused by the long-term use of these dental restoration materials. However, AgNPs can be absorbed into the blood circulatory system through the nasal/oral mucosa, lungs, gastrointestinal tract, skin, and other pathways and then distributed into the lungs, kidneys, liver, spleen, and testes, thereby causing toxic injury to these tissues and organs. It can even be transported across the blood-brain barrier (BBB) and continuously accumulate in brain tissues, causing injury and dysfunction of neurons and glial cells; consequently, neurotoxicity occurs. Other nanomaterials with antibacterial or remineralization properties are added to dental restoration materials with AgNPs. However, studies have yet to reveal the neurotoxicity caused by dental restoration materials containing AgNPs. In this review, we summarize the application of AgNPs in dental restoration materials, the mechanism of AgNPs in cytotoxicity and toxic injury to the BBB, and the related research on the accumulation of AgNPs to cause changes of neurotoxicity. We also discuss the mechanisms of neurotoxicity caused by AgNPs and the mode and rate of AgNPs released from dental restorative materials added with AgNPs to evaluate the probability of neurotoxic injury to the central nervous system (CNS), and then provide a theoretical basis for developing new composite dental restoration materials. Mechanism of neurotoxicity caused by AgNPs: AgNPs in the blood circulation enter the brain tissue after being transported across the BBB through transendothelial cell pathway and paracellular transport pathway, and continuously accumulate in brain tissue, causing damage and dysfunction of neurons and glial cells which ultimately leads to neurotoxicity. The uptake of AgNPs by neurons, astrocytes and microglia causes damage to these cells. AgNPs with non-neurotoxic level often increases the secretion of a variety of cytokines, up-regulates the expression of metallothionein in glial cells, even up-regulates autophagy and inflammation response to protect neurons from the toxic damage of AgNPs. However, the protective effect of glial cells induced by AgNPs exposure to neurotoxic levels is insufficient, which leads to neuronal damage and dysfunction and even neuronal programmed cell death, eventually cause neurotoxicity.

Nanoparticles-induced potential toxicity on human health: Applications, toxicity mechanisms, and evaluation models

Nanoparticles (NPs) have become one of the most popular objects of scientific study during the past decades. However, despite wealth of study reports, still there is a gap, particularly in health toxicology studies, underlying mechanisms, and related evaluation models to deeply understanding the NPs risk effects. In this review, we first present a comprehensive landscape of the applications of NPs on health, especially addressing the role of NPs in medical diagnosis, therapy. Then, the toxicity of NPs on health systems is introduced. We describe in detail the effects of NPs on various systems, including respiratory, nervous, endocrine, immune, and reproductive systems, and the carcinogenicity of NPs. Furthermore, we unravels the underlying mechanisms of NPs including ROS accumulation, mitochondrial damage, inflammatory reaction, apoptosis, DNA damage, cell cycle, and epigenetic regulation. In addition, the classical study models such as cell lines and mice and the emerging models such as 3D organoids used for evaluating the toxicity or scientific study are both introduced. Overall, this review presents a critical summary and evaluation of the state of understanding of NPs, giving readers more better understanding of the NPs toxicology to remedy key gaps in knowledge and techniques.

Atmospheric microplastic and nanoplastic: The toxicological paradigm on the cellular system

The increasing demand for plastic in our daily lives has led to global plastic pollution. The improper disposal of plastic has resulted in a massive amount of atmospheric microplastics (MPs), which has further resulted in the production of atmospheric nanoplastics (NPs). Because of its intimate relationship with the environment and human health, microplastic and nanoplastic contamination is becoming a problem. Because microplastics and nanoplastics are microscopic and light, they may penetrate deep into the human lungs. Despite several studies demonstrating the abundance of microplastics and nanoplastics in the air, the potential risks of atmospheric microplastics and nanoplastics remain unknown. Because of its small size, atmospheric nanoplastic characterization has presented significant challenges. This paper describes sampling and characterization procedures for atmospheric microplastics and nanoplastics. This study also examines the numerous harmful effects of plastic particles on human health and other species. There is a significant void in research on the toxicity of airborne microplastics and nanoplastics upon inhalation, which has significant toxicological potential in the future. Further study is needed to determine the influence of microplastic and nanoplastic on pulmonary diseases.

Zinc nanoparticles ameliorate oxidative stress and apoptosis induced by silver nanoparticles in the brain of male rats

The current study was conducted to investigate the possible ameliorative role of zinc nanoparticles (Zn NPs) against silver nanoparticles (Ag NPs)-induced oxidative and apoptotic brain damage in adult male rats. Twenty-four mature Wistar rats were randomly and equally divided into four groups: control group, Ag NPs group, Zn NPs group, and Ag NPs + Zn NPs group. Rats were exposed to Ag NPs (50 mg/kg) and/or Zn NPs (30 mg/kg) daily by oral gavage for 12 weeks. The results revealed that exposure to Ag NPs significantly increased malondialdehyde (MDA) content, decreased catalase and reduced glutathione (GSH) activities, downregulated the relative mRNA expression of antioxidant-related genes (Nrf-2 and SOD), and upregulated the relative mRNA expression of apoptosis-related genes (Bax, caspase 3 and caspase 9) in the brain tissue. Furthermore, severe neuropathological lesions with a substantial increase in the caspase 3 and glial fibrillary acidic protein (GFAP) immunoreactivity were observed in the cerebrum and cerebellum of Ag NPs-exposed rats. Conversely, co-administration of Zn NPs with Ag NPs significantly ameliorated most of these neurotoxic effects. Collectively, Zn NPs can be used as a potent prophylactic agent against Ag NPs-induced oxidative and apoptotic neural damage.

Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility

Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

Effective decolonization strategy for mupirocin-resistant Staphylococcus aureus by TPGS-modified mupirocin-silver complex

The widespread utilization of mupirocin to treat methicillin-resistant Staphylococcus aureus (MRSA)-caused infectious diseases has led to the emergence of mupirocin-resistant Staphylococcus aureus (MuRSA), posing a serious global medical threat. In order to counteract MuRSA, we develop a d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) modified mupirocin and silver complex (TPGS/Mup-Ag) to combat MuRSA. The surfactivity of TPGS endows Mup-Ag with a homogeneous and small particle size (∼16 ​nm), which significantly enhances bacterial internalization. Silver ions are released from the mupirocin-Ag complex (Mup-Ag) to exert a synergistic antibacterial activity with mupirocin. Results manifest that our strategy reduces the concentration of mupirocin that induces 50% bacterial death from about 1000 ​μmol/mL to about 16 ​μmol/mL. In vitro bacterial infection model suggests that TPGS/Mup-Ag can not only eliminate both intracellular and inhibit bacterial adhesion, but also living cells are not affected. Results of in vivo experiments demonstrate that TPGS/Mup-Ag can effectively inhibit the progression of skin infection and accelerate wound healing, as well as alleviate systemic inflammation in both the subcutaneous infection model and the wound infection model. Furthermore, this study may contribute to the development of therapeutic agents for antibiotic-resistant bacteria and offer ideas for silver-based bactericides.

Toxic implications of silver nanoparticles on the central nervous system: A systematic literature review

Silver nanoparticles have many medical and commercial applications, but their effects on human health are poorly understood. They are used extensively in products of daily use, but little is known about their potential neurotoxic effects. A xenobiotic metal, silver, has no known physiological significance in the human body as a trace metal. Biokinetics of silver nanoparticles indicates its elimination from the body via urine and feces route. However, a substantial amount of evidence from both in vitro and in vivo experimental research unequivocally establish the fact of easier penetration of smaller nanoparticles across the blood-brain barrier to enter in brain and thereby interaction with cellular components to induce neurotoxic effects. Toxicological effects of silver nanoparticles rely on the degree of exposure, particle size, surface coating, and agglomeration state as well as the type of cell or organism used to evaluate its toxicity. This review covers pertinent facts and the present state of knowledge about the neurotoxicity of silver nanoparticles reviewing the impacts on oxidative stress, neuroinflammation, mitochondrial function, neurodegeneration, apoptosis, and necrosis. The effect of silver nanoparticles on the central nervous system is a topic of growing interest and concern that requires immediate consideration.

Detection and modulation of neurodegenerative processes using graphene-based nanomaterials: Nanoarchitectonics and applications

Neurodegenerative disorders (NDDs) are caused by progressive loss of functional neurons following the aggregation and fibrillation of proteins in the central nervous system. The incidence rate continues to rise alarmingly worldwide, particularly in aged population, and the success of treatment remains limited to symptomatic relief. Graphene nanomaterials (GNs) have attracted immense interest on the account of their unique physicochemical and optoelectronic properties. The research over the past two decades has recognized their ability to interact with aggregation-prone neuronal proteins, regulate autophagy and modulate the electrophysiology of neuronal cells. Graphene can prevent the formation of higher order protein aggregates and facilitate the clearance of such deposits. In this review, after highlighting the role of protein fibrillation in neurodegeneration, we have discussed how GN-protein interactions can be exploited for preventing neurodegeneration. A comprehensive understanding of such interactions would contribute to the exploration of novel modalities for controlling neurodegenerative processes.

Effects of ecotoxicity of penoxsulam single and co-exposure with AgNPs on Eisenia fetida

Penoxsulam (PNX) and silver nanoparticles (AgNPs) are likely to coexist in soils due to continuous use. However, the ecotoxicity of PNX in earthworms and the effect of AgNPs on PNX toxicity are unknown. Therefore, the toxicity of PNX (0.05, 0.5, and 2.5 mg/kg) single and co-exposure with AgNPs (10 mg/kg) after 28 and 56 days on Eisenia fetida (E. fetida) was investigated from biochemical, genetic, histopathological, and transcriptomic aspects. The results showed that the low concentration of PNX (0.05PNX) had almost no effect on the biochemical level of E. fetida. However, the addition of AgNPs resulted in 0.05PNX causing E. fetida to produce excessive reactive oxygen species, and the activity of antioxidant and detoxification enzymes were interfered, resulting in lipid peroxidation and DNA damage. From the genetic level, even the lowest concentration of PNX can significantly interfere with the expression of functional genes, thus inducing oxidative stress and apoptosis and inhibited reproductive behavior in E. fetida. The integrated biomarker response results at the biochemical and genetic levels showed that the comprehensive toxicity of PNX and PNX + AgNPs on E. fetida was PNX dose-dependent. And the toxicity of all co-exposure groups was greater than that of the PNX only exposure groups. Furthermore, the addition of AgNPs significantly increased the damage of PNX on E. fetida intestinal tissue. Meanwhile, transcriptomic analysis showed that PNX + AgNPs had a greater effect on E. fetida than PNX single, and multiple pathways related to oxidative stress, inflammation, and cellular process regulation were disturbed. These results provide a basis for comprehensive evaluation of the ecotoxicity of PNX and confirm that the AgNPs does increase the ecotoxicity of PNX in soil environment.

Coating-Dependent Neurotoxicity of Silver Nanoparticles—An In Vivo Study on Hippocampal Oxidative Stress and Neurosteroids

Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials. The level of exposure to nanosilver is constantly raising, and a growing body of research highlights that it is harmful to the health, especially the nervous system, of humans. The potential pathways through which nanosilver affects neurons include the release of silver ions and the associated induction of oxidative stress. To better understand the mechanisms underlying the neurotoxicity of nanosilver, in this study we exposed male Wistar rats to 0.5 mg/kg body weight of AgNPs coated with bovine serum albumin (BSA), polyethylene glycol (PEG), or citrate, or to AgNO₃ as a source of silver ions for 28 days and assessed the expression of antioxidant defense markers in the hippocampus of the exposed animals after 1 week of spatial memory training. We also evaluated the influence of AgNPs coating on neurosteroidogenesis in the rat hippocampus. The results showed that AgNPs disrupted the antioxidant system in the hippocampus and induced oxidative stress in a coating-dependent manner, which could potentially be responsible for neurodegeneration and cognitive disorders. The analysis of the influence of AgNPs on neurosteroids also indicated coating-dependent modulation of steroid levels with a significant decrease in the concentrations of progesterone and 17α-progesterone in AgNPs(BSA), AgNPs(PEG), and Ag⁺ groups. Furthermore, exposure to AgNPs or Ag⁺ resulted in the downregulation of selected genes involved in antioxidant defense (Cat), neurosteroid synthesis (Star, Hsd3b3, Hsd17b1, and Hsd17b10), and steroid metabolism (Ar, Er1, and Er2). In conclusion, depending on the coating material used for their stabilization, AgNPs induced oxidative stress and modulated the concentrations of steroids as well as the expression of genes involved in steroid synthesis and metabolism.

Nanoparticles in Combating Neuronal Dysregulated Signaling Pathways: Recent Approaches to the Nanoformulations of Phytochemicals and Synthetic Drugs Against Neurodegenerative Diseases

As the worldwide average life expectancy has grown, the prevalence of age-related neurodegenerative diseases (NDDs) has risen dramatically. A progressive loss of neuronal function characterizes NDDs, usually followed by neuronal death. Inflammation, apoptosis, oxidative stress, and protein misfolding are critical dysregulated signaling pathways that mainly orchestrate neuronal damage from a mechanistic point. Furthermore, in afflicted families with genetic anomalies, mutations and multiplications of α-synuclein and amyloid-related genes produce some kinds of NDDs. Overproduction of such proteins, and their excessive aggregation, have been proven in various models of neuronal malfunction and death. In this line, providing multi-target therapies carried by novel delivery systems would pave the road to control NDDs through simultaneous modulation of such dysregulated pathways. Phytochemicals are multi-target therapeutic agents, which employ several mechanisms towards neuroprotection. Besides, the blood-brain barrier (BBB) is a critical issue in managing NDDs since it inhibits the accessibility of drugs to the brain in sufficient concentration. Besides, discovering novel delivery systems is vital to improving the efficacy, bioavailability, and pharmacokinetic of therapeutic agents. Such novel formulations are also employed to improve the drug's biodistribution, allow for the co-delivery of several medicines, and offer targeted intracellular delivery against NDDs. The present review proposes nanoformulations of phytochemicals and synthetic agents to combat NDDs by modulating neuroinflammation, neuroapoptosis, neuronal oxidative stress pathways and protein misfolding.

Assessment of the Ecotoxicity of Pollution by Potentially Toxic Elements by Biological Indicators of Haplic Chernozem of Southern Russia (Rostov region)

The content of various chemical elements such as metals, metalloids, and nonmetals in the environment is associated with natural and anthropogenic sources. It is necessary to normalize the content of metals, metalloids, and nonmetals as potentially toxic elements (PTE) in the Haplic Chernozem. The soils of the Southern Russia are of high quality and fertility. However, this type of soil, like Haplic Chernozem, is subject to contamination with a wide range of PTE. The aim of the work was to rank metals, metalloids, and nonmetals by ecotoxicity in Haplic Chernozem. To assess the ecotoxicity of chernozem, data for 15 years (2005-2020) were used. Biological indicators used to assess the ecotoxicity of Haplic Chernozem: catalase activity, cellulolytic activity, number of bacteria, Azotobacter spp. abundance, to change of length of radish's roots. Based on these biological indicators, an integral indicator of the state of Haplic Chernozem was calculated. The ecotoxicity of 23 metals (Cd, Hg, Pb, Cr, Cu, Zn, Ni, Co, Mo, Mn, Ba, Sr, Sn, V, W, Ag, Bi, Ga, Nb, Sc, Tl, Y, Yb), 5 metalloids (B, As, Ge, Sb, Te) and 2 nonmetals (F, Se) as priority pollutants. It is proposed to distinguish three hazard classes of metals, metalloids, and nonmetals to Haplic Chernozem: I class - Te, Ag, Se, Cr, Bi, Ge, Sn, Tl, Hg, Yb, W, Cd; II class - As, Co, Sc, Sb, Cu, Ni, B, Nb, Pb, Ga; III class - Sr, Y, Mo, Zn, V, Ba, Mn, F. It is advisable to use the results of the study for predictive assessment of the impact of metals, metalloids, and nonmetals on the ecological state of the soil during pollution.

Potential cytotoxicity of silver nanoparticles: Stimulation of autophagy and mitochondrial dysfunction in cardiac cells

In the present study, we elucidated the potential cytotoxicity of AgNPs in H9c2 rat cardiomyoblasts and assessed the underlying toxicological manifestations responsible for their toxicity thereof. The results indicated that the exposure of AgNPs to H9c2 cardiac cells decreased cell viability in a dose-dependent manner and caused cell cycle arrest followed by induction of apoptosis. The AgNPs treated cardiac cells showed a generation of reactive oxygen species (ROS) and mitochondrial dysfunction where mitochondrial ATP was reduced and the expression of AMPK1α increased. AgNPs also induced ROS-mediated autophagy in H9c2 cells. There was a significant time-dependent increase in intracellular levels of Atg5, Beclin1, and LC3BII after exposure to AgNPs, signifying the autophagic response in H9c2 cells. More importantly, the addition of N-acetyl-L-cysteine (NAC) inhibited autophagy and significantly reduced the cytotoxicity of AgNPs in H9c2 cells. The study highlights the prospective toxicity of AgNPs on cardiac cells, collectively signifying a potential health risk.

Astrocyte responses to nanomaterials: Functional changes, pathological changes and potential applications

Astrocytes are responsible for regulating and optimizing the functional environment of neurons in the brain and can reduce the adverse impacts of external factors by protecting neurons. However, excessive astrocyte activation upon stimulation may alter their initial protective effect and actually lead to aggravation of injury. Similar to the dual effects of astrocytes in the response to injury within the central nervous system (CNS), nanomaterials (NMs) can have either toxic or beneficial effects on astrocytes, serving to promote injury or inhibit tumors. As the important physiological functions of astrocytes have been gradually revealed, the effects of NMs on astrocytes and the underlying mechanisms have become a new frontier in nanomedicine and neuroscience. This review summarizes the in vitro and in vivo findings regarding the effects of various NMs on astrocytes, focusing on functional alterations and pathological processes in astrocytes, as well as the possible underlying mechanisms. We also emphasize the importance of co-culture models in studying the interaction between NMs and cells of the CNS. Finally, we discuss NMs that have shown promise for application in astrocyte-related diseases and propose some challenges and suggestions for further investigations, with the aim of providing guidance for the widespread application of NMs in the CNS.

Disturbance in Mammalian Cognition Caused by Accumulation of Silver in Brain

The influence of daily prolonged administration of silver nanoparticles on the cognitive functions of a model mammal was studied. The accumulation of silver in the whole brain and the hippocampus, cerebellum, cortex and residual brain tissue of the mouse was investigated by highly precise and representative neutron activation analysis, and histological studies were conducted. Here, we show that long-term memory impairments were caused by the accumulation of silver nanoparticles in the brain and its subregions, such as the hippocampus, cerebellum and cortex, in a step-like manner by disturbance of hippocampal cell integrity. Three different approaches allowed us to observe this phenomenon and discover the reasons it occurred.

Gold nanoparticles produce transient reactive gliosis in the adult brain

Gold nanoparticles (GNPs) have unique physical and chemical properties that allow them to function as a drug-delivery system for several tissues: skin, eye, liver, and others. However, information about the biological response of brain tissue against GNPs is limited. Astrocytes and microglia cells are the first line of defense against brain insults and proper indicators of the level of brain damage. This study was aimed to evaluate the astrocytic and microglia response after an intracerebral injection of polyethylene-glycol-coupled GNPs (PEGylated GNPs). We injected spherical PEGylated GNPs (85 × 10⁶ nanoparticles /nl) with a glass micropipette (inner diameter =35 μm) into the striatum of P60 CD1 mice. We evaluated the cellular response of astrocytes and microglia on days 3, 7, 14, 30, and 90 after intracerebral injection. For both astrocytes and microglia cells, our findings indicated that the glial response was transient and mainly circumscribed to the injection site. This evidence suggests that PEGylated GNPs are well-tolerated by the neural tissue. Understanding the effects of GNPs in the adult brain is a crucial step to design proper pharmacological vehicles to deliver long-lasting drugs.

The Toxic Effect of Silver Nanoparticles on Nerve Cells: A Systematic Review and Meta-Analysis

Despite the increasing use of silver nanoparticles in medical sciences, published studies on their interaction with nerve cells and evaluation of risks are dispersed. This systematic review and meta-analysis could be used to devise safety guidelines for the use of silver nanoparticles in industry and medicine to reduce adverse effects on the CNS.After extensive searches, the full text of 30 related studies was reviewed and data mining completed. Data were analyzed by calculating the mean of different ratios between treated and untreated groups. Linear regression between variables was evaluated by meta-regression. Subgroup analysis was also performed due to heterogeneity.Treatment with silver nanoparticles significantly reduced cell viability (SMD = -1.79%; 95% CI: -2.17 to -1.40; p < 0.0001). Concentration > 0.1 μg/mL could kill neurons, while lower concentration would not (SMD -0.258; 95% CI: -0.821 to 0.305; p = 369). In addition to the concentration, the coating, size of the nanoparticles, and cell type are also factors that influence SNP nerve cell toxicity. Measurement of apoptosis (SMD = 2.21; 95% CI: 1.62 to 2.80; p=0.001) and lactate dehydrogenase release rate (SMD = 0.9; 95% CI: 0.33 to 1.47; p < 0.0001) also confirmed the destructive effect of silver nanoparticles on nerve cells.

Synergistic effects of immunoregulation and osteoinduction of ds-block elements on titanium surface

Ds-block elements have been gaining increasing attention in the field of biomaterials modification, owing to their excellent biological properties, such as antibiosis, osteogenesis, etc. However, their function mechanisms are not well understood and conflicting conclusions were drawn by previous studies on this issue, which are mainly resulted from the inconsistent experimental conditions. In this work, three most widely used ds-block elements, copper, zinc, and silver were introduced on titanium substrate by plasma immersion ion implantation method to investigate the rule of ds-block elements in the immune responses. Results showed that the implanted samples could decrease the inflammatory responses compared with Ti sample. The trend of anti-inflammatory effects of macrophages on samples was in correlation with cellular ROS levels, which was induced by the implanted biomaterials and positively correlated with the number of valence electrons of ds-block elements. The co-culture experiments of macrophages and bone marrow mesenchymal stem cells showed that these two kinds of cells could enhance the anti-inflammation and osteogenesis of samples by the paracrine manner of PGE2. In general, in their steady states on titanium substrate (Cu2+, Zn2+, Ag), the ds-block elements with more valence electrons exhibit better anti-inflammatory and osteogenic effects. Moreover, molecular biology experiments indicate that the PGE2-related signaling pathway may contribute to the desired immunoregulation and osteoinduction capability of ds-block elements. These findings suggest a correlation between the number of valence electrons of ds-block elements and the relevant biological responses, which provides new insight into the selection of implanted ions and surface design of biomaterials.

Tranilast ameliorated subchronic silver nanoparticles-induced cerebral toxicity in rats: Effect on TLR4/NLRP3 and Nrf-2

Silver nanoparticles (AgNPs) are widely applied in various aspects of life. However, recent studies reported their potential toxicity both on environment and human health. The present study aimed to unravel the underlying molecular mechanisms involved in AgNPs-induced brain toxicity. Moreover, chemopreventive effect of tranilast, an analogue of tryptophan metabolite and a mast cell membrane stabilizer was evaluated. Thirty Sprague Dawley rats were enrolled equally into Normal control group, AgNPs-intoxicated group (50 mg/kg, 3 times/week) and tranilast (300 mg/kg, 3 times/week)+AgNPs group. AgNPs administration triggered brain oxidative stress as depicted by reduced Nrf-2 expression, decreased TAC and GSH as well as upregulated brain lipid peroxidation. The apparent brain oxidative damage was accompanied by elevated levels of inflammatory cytokines (IL-1β, IL-6 and TNF-α). Moreover, brain levels of TLR4, NLRP3 and caspase-1 were up-regulated. Additionally, histological study indicated marked cellular injury in cerebrum and cerebellum specimens. This was concomitant with elevated serum CK activity and CK-BB level. On the other hand, tanilast administration remarkably alleviated AgNPs-induced brain toxicity. The present study shed the light on implication of TLR4/NLRP3 axis and NrF2 in AgNPs-induced brain toxicity. In addition, it explored the potential protective effect of tranilast on AgNPs-induced brain injury via antioxidant and anti-inflammatory efficacies.

Cellular, Molecular and Biochemical Impacts of Silver Nanoparticles on Rat Cerebellar Cortex

BACKGROUND

The excessive exposure to silver nanoparticles (Ag-NPs) has raised concerns about their possible risks to the human health. The brain is a highly vulnerable organ to nano-silver harmfulness. The aim of this work was to evaluate the impacts of Ag-NPs exposure on the cerebellar cortex of rats.

METHODS

Rats were assigned to: Control, vehicle control and Ag-NP-exposed groups (at doses of 10 mg and 30 mg/kg/day). Samples were processed for light and electron microscopy examinations. Immunohistochemical localization of c-Jun N-terminal kinase (JNK), nuclear factor kappa beta (NF-κB) and calbindin D28k (CB) proteins was performed. Analyses of expression of DNA damage inducible transcript 4 (Ddit4), flavin containing monooxygenase 2 (FMO2) and thioredoxin-interacting protein (Txnip) genes were done. Serum levels of inflammatory cytokines were also measured.

RESULTS

Ag-NPs enhanced apoptosis as evident by upregulation of Ddit4 gene expressions and JNK protein immune expressions. Alterations of redox homeostasis were verified by enhancement of Txnip and FMO2 gene expressions, favoring the activation of inflammatory responses by increasing NF-κB protein immune expressions and serum inflammatory mediator levels. Another cytotoxic effect was the reduction of immune expressions of the calcium regulator CB.

CONCLUSION

Ag-NPs exposure provoked biochemical, cellular and molecular changes of rat cerebellar cortex in a dose-dependent manner.

Antimicrobial efficacy of platinum-doped silver nanoparticles

Silver nanoparticles (AgNPs) have been proposed to combat oral infection due to their efficient ionic silver (Ag+ ) release. However, concentrations required for antimicrobial efficacy may not be therapeutically viable. In this work, platinum-doped silver nanoparticles (Pt-AgNPs) were explored to evaluate their potential for enhanced Ag+ release, which could lead to enhanced antimicrobial efficacy against S. aureus, P. aeruginosa, and E. coli. AgNPs doped with 0.5, 1, and 2 mol% platinum (Pt0.5 -AgNPs, Pt1 -AgNPs, and Pt2 -AgNPs) were synthesized by a chemical reduction method. Transmission electron microscopy revealed mixed morphologies of spherical, oval, and ribbon-like nanostructures. Surface-enhanced Raman scattering revealed that the surface of Pt-AgNPs was covered with up to 93% Pt. The amount of Ag+ released increased 16.3-fold for Pt2 -AgNPs, compared to AgNPs. The initial lag phase in bacterial growth curve was prolonged for Pt-AgNPs. This is consistent with a Ag+ release profile that exhibited an initial burst followed by sustained release. Doping AgNPs with platinum significantly increased the antimicrobial efficacy against all species. Pt2 -AgNPs exhibited the lowest minimum inhibitory concentrations, followed by Pt1 -AgNPs, Pt0.5 -AgNPs, and AgNPs, respectively. Doping AgNPs with a small amount of platinum promoted the release of Ag+ , based on the sacrificial anodic effect, and subsequently enhanced their antimicrobial efficacy.

Biomass-derived cellulose nanoparticles display considerable neurotoxicity in zebrafish

The widespread use of nanomaterials poses a great threat to human living environments. Among them, biomass-derived cellulose nanoparticle (CN) is one of the widely used nanomaterials. To date, the toxicity of CNs during embryonic development remains undetermined. In this study, we exposed zebrafish embryos to cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) to evaluate the toxicity of these CNs. Exposure to CNFs or CNCs below 30 mg/ml exhibited no dose-dependent increases in malformation and mortality in zebrafish embryos. Then we demonstrated that CNs were highly enriched in zebrafish embryo via imaging analyses of embryos treated with FITC-coupled CNCs. In addition, we found that CNF or CNC exposure resulted in compromised motor ability of zebrafish larva. Furthermore, it was revealed that the differentiation and the morphogenesis of motor neurons were significantly interrupted. While, blood vessels were normally patterned, suggesting the specific neurotoxicity of these nanomaterials. Transcriptome sequencing assay showed that the neurotoxicity of CNs in the motor neurons might be attributed to the expression alteration of neural genes. In summary, we discovered the neurotoxicity of CNs for the first time.

Silver nanoparticles induce size-dependent and particle-specific neurotoxicity to primary cultures of rat cerebral cortical neurons

Silver nanoparticles (AgNPs) are widely applied in many fields because of their excellent antibacterial activities. Toxicological studies have showed that AgNPs can cross the blood-brain barrier and exhibit high retention in the brain. Therefore, the potential neurotoxicity of AgNPs is raising serious concerns. This study investigated the neurotoxicological effects of AgNPs with two different sizes (20 nm and 70 nm, AgNPs-20 and AgNPs-70) using primary cultures of rat cerebral cortical neurons in mature and developing stages. The contribution of silver ion release was investigated by testing the effects of ionic silver in parallel. The results showed that both AgNPs-20 and AgNPs-70 significantly decreased neuronal cell viability, and AgNPs-20 had stronger toxicity compared with AgNPs-70. AgNP applications caused the granulated skeleton structure of the mature neurons with some broken synapses after a 24-h exposure, and inhibited neuronal growth during a 7-day exposure. Intracellular silver accumulation at non-cytotoxic exposure levels inhibited dopamine efflux, which was particle-specific and free of released silver ions. The findings herein can aid in guiding the proper applications of AgNPs in different areas, especially in medical use.

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.

Toxicity of Ag+ on microstructure, biochemical activities and genic material of Trifolium pratense L. seedlings with special reference to phytoremediation

The objective of this research was to evaluate Ag⁺ toxicity in Trifolium pratense L. seedlings subjected to increasing doses of Ag⁺ by determining photosynthetic pigment and malondialdehyde (MDA) contents, microstructure and hereditary substance alterations, changes in activities of antioxidase-superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) as well as the content of total Ag absorbed in vivo with evaluation of root growth. Doses of approximately 80 mg L^-1 Ag⁺ severely affected photosynthetic efficiency in Trifolium pratense L. seedlings promoted by damages in photosynthetic apparatus evidenced by downward trend in photosynthetic pigment contents and obvious chlorosis. Alterations in enzymatic activity, lipid peroxidation, genic material damage and the presence of Ag⁺in vivo had impacted on photosynthetic machinery as well. A hormesis effect was observed at 60 mg L^-1 Ag⁺ for the photosynthetic pigments and antioxidase for Trifolium pratense L. seedlings. Tissue changes (i.e., roots, stems and leaves) observed in fluorescence microscope with obvious chlorosis, roots blackening and formation of agglomerated black particles, were related to the lesion promoted by excessive ROS in vivo. Asynchronous change of antioxidase activity corresponded to the alteration in the MDA content, indicating the synchronization in the elimination of ROS. The changes occurred in RAPD profiles of treated samples following Ag⁺ toxicity containing loss of normal bands, appearance of new bands and variation in band intensity compared to the normal plants with a dose-dependent effect. On average, the roots of Trifolium pratense L. immobilized 92.20% of the total Ag absorbed as a metal exclusion response. Root growth was significantly sensitive to Ag⁺ stress with obvious hormesis, which corresponded to the changes in Ag uptake, demonstrating the functional alterations in plants. To sum up, we suggest that modulating the genotype of Trifolium pratense L. seedlings to bear higher proportion of pollutants is conducive to contamination site treatment.

Intranasal Delivery of Nanoformulations: A Potential Way of Treatment for Neurological Disorders

Although the global prevalence of neurological disorders such as Parkinson’s disease, Alzheimer’s disease, glioblastoma, epilepsy, and multiple sclerosis is steadily increasing, effective delivery of drug molecules in therapeutic quantities to the central nervous system (CNS) is still lacking. The blood brain barrier (BBB) is the major obstacle for the entry of drugs into the brain, as it comprises a tight layer of endothelial cells surrounded by astrocyte foot processes that limit drugs’ entry. In recent times, intranasal drug delivery has emerged as a reliable method to bypass the BBB and treat neurological diseases. The intranasal route for drug delivery to the brain with both solution and particulate formulations has been demonstrated repeatedly in preclinical models, including in human trials. The key features determining the efficacy of drug delivery via the intranasal route include delivery to the olfactory area of the nares, a longer retention time at the nasal mucosal surface, enhanced penetration of the drugs through the nasal epithelia, and reduced drug metabolism in the nasal cavity. This review describes important neurological disorders, challenges in drug delivery to the disordered CNS, and new nasal delivery techniques designed to overcome these challenges and facilitate more efficient and targeted drug delivery. The potential for treatment possibilities with intranasal transfer of drugs will increase with the development of more effective formulations and delivery devices.

Health Impact of Silver Nanoparticles: A Review of the Biodistribution and Toxicity Following Various Routes of Exposure

Engineered nanomaterials (ENMs) have gained huge importance in technological advancements over the past few years. Among the various ENMs, silver nanoparticles (AgNPs) have become one of the most explored nanotechnology-derived nanostructures and have been intensively investigated for their unique physicochemical properties. The widespread commercial and biomedical application of nanosilver include its use as a catalyst and an optical receptor in cosmetics, electronics and textile engineering, as a bactericidal agent, and in wound dressings, surgical instruments, and disinfectants. This, in turn, has increased the potential for interactions of AgNPs with terrestrial and aquatic environments, as well as potential exposure and toxicity to human health. In the present review, after giving an overview of ENMs, we discuss the current advances on the physiochemical properties of AgNPs with specific emphasis on biodistribution and both in vitro and in vivo toxicity following various routes of exposure. Most in vitro studies have demonstrated the size-, dose- and coating-dependent cellular uptake of AgNPs. Following NPs exposure, in vivo biodistribution studies have reported Ag accumulation and toxicity to local as well as distant organs. Though there has been an increase in the number of studies in this area, more investigations are required to understand the mechanisms of toxicity following various modes of exposure to AgNPs.

The interrupted effect of autophagic flux and lysosomal function induced by graphene oxide in p62-dependent apoptosis of F98 cells

BACKGROUND

Graphene oxide (GO) nanoparticles (NPs) have been widely applied in various fields, especially in biomedical applications. Extensive studies have suggested that GO can pass through the blood-brain barrier (BBB) and induce abnormal autophagy and cytotoxicity in the central nervous system (CNS). However, the effect and specific mechanism of GO on astrocytes, the most abundant cells in the brain still has not been extensively investigated.

RESULTS

In this study, we systematically explored the toxicity and mechanism of GO exposure in the rat astroglioma-derived F98 cell line using molecular biological techniques (immunofluorescence staining, flow cytometry and Western blot) at the subcellular level and the signaling pathway level. Cells exposed to GO exhibited decreased cell viability and increased lactate dehydrogenase (LDH) release in a concentration- and time-dependent manner. GO-induced autophagy was evidenced by transmission electron microscopy (TEM) and immunofluorescence staining. Western blots showed that LC3II/I and p62 were upregulated and PI3K/Akt/mTOR was downregulated. Detection of lysosomal acidity and cathepsin B activity assay indicated the impairment of lysosomal function. Annexin V-FITC-PI detection showed the occurrence of apoptosis after GO exposure. The decrease in mitochondrial membrane potential (MMP) with an accompanying upregulation of cleaved caspase-3 and Bax/Bcl-2 further suggested that endogenous signaling pathways were involved in GO-induced apoptosis.

CONCLUSION

The exposure of F98 cells to GO can elicit concentration- and time-dependent toxicological effects. Additionally, increased autophagic response can be triggered after GO treatment and that the blocking of autophagy flux plays a vital role in GO cytotoxicity, which was determined to be related to dysfunction of lysosomal degradation. Importantly, the abnormal accumulation of autophagic substrate p62 protein can induce capase-3-mediated apoptosis. Inhibition of abnormal accumulation of autophagic cargo could alleviate the occurrence of GO-induced apoptosis in F98 cells.

Hazard characterization of silver nanoparticles for human exposure routes

Silver nanoparticles (AgNPs) have been widely used for a multitude of applications without full comprehensive knowledge regarding their safety. In particular, lack of data on hazard characterization may lead to uncertainties regarding potential human health risk. To provide the foundation for human health risk assessment of AgNPs, this study evaluates existing hazard characterization data, including reported pharmacokinetics, symptoms, and their corresponding dose-response relationships. Human equivalent relationships are also provided by extrapolation from animal dose-response relationships. From the data analyzed, it appears that AgNPs may persist for long periods (from days to years) in the human body. It was found that AgNP toxicity on traditional major targets of exogenous substances were generally underestimated. Some omissions of toxicity on sensitive systems in the AgNP toxicity assessment require attention, such as reprotoxicity and neurotoxicity. The necessity of the establishment of toxicity tests specifically for nanomaterials is highlighted. The scientific basis of a toxicity testing strategy is advised by this study, which paves the way for the monitoring and regulation of the ENP utilization in various industries.

Mitochondrial Peptide Humanin Protects Silver Nanoparticles-Induced Neurotoxicity in Human Neuroblastoma Cancer Cells (SH-SY5Y)

The extensive usage of silver nanoparticles (AgNPs) as medical products such as antimicrobial and anticancer agents has raised concerns about their harmful effects on human beings. AgNPs can potentially induce oxidative stress and apoptosis in cells. However, humanin (HN) is a small secreted peptide that has cytoprotective and neuroprotective cellular effects. The aim of this study was to assess the harmful effects of AgNPs on human neuroblastoma SH-SY5Y cells and also to investigate the protective effect of HN from AgNPs-induced cell death, mitochondrial dysfunctions, DNA damage, and apoptosis. AgNPs were prepared with an average size of 18 nm diameter to study their interaction with SH-SY5Y cells. AgNPs caused a dose-dependent decrease of cell viability and proliferation, induced loss of plasma-membrane integrity, oxidative stress, loss of mitochondrial membrane potential (MMP), and loss of ATP content, amongst other effects. Pretreatment or co-treatment of HN with AgNPs protected cells from several of these AgNPs induced adverse effects. Thus, this study demonstrated for the first time that HN protected neuroblastoma cells against AgNPs-induced neurotoxicity. The mechanisms of the HN-mediated protective effect on neuroblastoma cells may provide further insights for the development of novel therapeutic agents against neurodegenerative diseases.

Combination analysis of the physiology and transcriptome provides insights into the mechanism of silver nanoparticles phytotoxicity

Silver nanoparticles (AgNPs) have adverse impacts on plants when released into environments, but their toxic mechanism is still a matter of debate. Here we present a combined analysis of physiology and transcriptome of Arabidopsis thaliana leaves exposure to 30 mg L^-1 AgNPs and Ag⁺ for six days to explore the toxicity mechanism of AgNPs on Arabidopsis. Both transcriptomic and physiological results showed that AgNPs induced reactive oxygen species (ROS) accumulation and damaged photosynthesis. The toxicity of AgNPs is not merely attributable to Ag⁺ release and much higher photosynthetic toxicity and ROS accumulation were observed in 30 mg L^-1 AgNPs than that in 0.12 mg L^-1 Ag⁺. About 60% genes were similarly up- or down-regulated at the same concentration of AgNPs and Ag⁺ and these genes were enriched in photosynthesis and response to the stimulus. However, 302 genes, including those involved in glucosinolates synthesis, were specifically regulated under AgNPs treatments. In conclusion, more than the released Ag⁺, nanoparticle-specific effects are responsible for the toxicity of AgNPs in Arabidopsis thaliana.

Antibacterial mechanism of silver nanoparticles in Pseudomonas aeruginosa: proteomics approach

Silver nanoparticles (AgNPs) are the nanomaterials most widely used as antimicrobial agents in a range of consumer products, due to the environmental release of either the AgNPs themselves or silver ions. Although AgNPs appear to be more potent than silver ions, the mechanism behind the activity is not fully elucidated yet. The most common mechanism of toxicity of AgNPs proposed to date is the release of silver ions and/or the particle-specific functions. In this study, Pseudomonas aeruginosa (a model for Gram-negative bacteria) was treated with AgNPs, and its proteomic response was comprehensively characterized to elucidate the antimicrobial mechanism of AgNPs in the microorganism. In total, 59 silver-regulated proteins (27 up-regulated and 32 down-regulated proteins) and 5 silver-binding proteins were identified. Bioinformatic analysis revealed that interference with the cell-membrane function and generation of intracellular reactive oxygen species (ROS) were the main pathways for the antibacterial effect. The pattern of membrane proteins regulated by AgNPs was similar to that found for silver ions. In addition, the same silver-binding proteins were obtained with both AgNPs and silver ions, which indicated that AgNPs probably affect the cell membrane and react with proteins by releasing silver ions. The elevation of intracellular ROS relative to that with silver ions confirmed oxidative damage caused by AgNPs, which may be ascribed to the nano-characteristics and higher uptake efficiency of the particles. These results demonstrate that the antimicrobial activity of AgNPs is due to the synergistic action of release of dissolved silver ions and particle-specific effects. The proteomic analysis of silver-binding and silver-regulated proteins in the present study provides insight into the mechanism of antimicrobial activity of such nanomaterials.

Silver nanoparticles induce abnormal touch responses by damaging neural circuits in zebrafish embryos

Although silver nanoparticles (AgNPs) are used in various commercial products, the biological effects of AgNPs on fish embryogenesis and the underlying molecular mechanisms are still poorly understood. In this study, both touch responses and neuron membrane potential were found to be abnormal in AgNPs-stressed embryos. Moreover, neurogenesis genes were unveiled to be down-regulated and were enriched in ligand-gated ion channel activity, dopamine receptor signaling pathway, etc. in AgNPs-stressed embryos by microarray assays. Additionally, the down-regulated expression of otpa/sncgb - gad1b/gad2 dopaminergic neurotransmitter genes, robo2 - vim and glrbb synaptic transmission genes, and motor neuron genes isl1 &isl2a was further identified in both AgNPs- and Ag⁺-stressed embryos by qPCR, whole-mount in situ hybridization (WISH), and by using specific promoter-derived GFP fluorescence transgenic zebrafish. Moreover, the reduced expression of gad1b, gad2, and isl1 could be recovered by adding Ag⁺ chelating compound l-cysteine in AgNPs stressed embryos. Our results reveal for the first time that it is through damaging the formation of neural circuits, including dopaminergic neurotransmitter, synaptic transmission, and motor activities, that AgNPs induce abnormal electrical membrane properties, leading to dysfunctional touch responses and locomotor escape responses mostly via their released Ag⁺ during embryogenesis.

Interaction between Silver Nanoparticles and Two Dehydrogenases: Role of Thiol Groups

Widely used silver nanoparticles (AgNPs) are readily accessible to biological fluids and then surrounded by proteins. However, interactions between AgNPs and proteins are poorly understood. Two dehydrogenases, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and malate dehydrogenase (MDH), are chosen to investigate these interactions. Ag bound to thiol groups of these enzymes significantly decreases the number of free thiols available. Dose-dependent inhibition of enzyme activities is observed in both AgNPs and Ag⁺ treatments. Based on the concentration required to inhibit 50% activity, GAPDH and MDH are 24-30 fold more sensitive to Ag⁺ than to AgNPs suggesting that the measured 4.2% Ag⁺ containing AgNPs can be responsible for the enzymes inhibition. GAPDH, with a thiol group in its active site, is more sensitive to Ag than MDH, displaying many thiol groups but none in its active site, suggesting that thiol groups at the active site strongly determines the sensitivity of enzymes toward AgNPs. In contrast, the dramatic changes of circular dichroism spectra show that the global secondary structure of MDH under AgNPs treatment is more altered than that of GAPDH. In summary, this study shows that the thiol groups and their location on these dehydrogenases are crucial for the AgNPs effects.

Silver nanoparticles inhibit beige fat function and promote adiposity

Objective

Obesity is a complex chronic disease of high prevalence worldwide. Multiple factors play integral roles in obesity development, with rising interest focusing on the contribution of environmental pollutants frequent in modern society. Silver nanoparticles (AgNPs) are widely used for bactericidal purpose in various applications in daily life. However, their potential toxicity and contribution to the obesity epidemic are not clear.

Methods

Beige adipocytes are newly discovered adipocytes characterized by high thermogenic and energy dissipating capacity upon activation and the “browning” process. In the present study, we assess the impact of AgNPs exposure on beige adipocytes differentiation and functionality both in vitro and in vivo. We also systematically investigate the influence of AgNPs on adiposity and metabolic performance in mice, as well as the possible underlying molecular mechanism.

Results

The results showed that, independent of particle size, AgNPs inhibit the adipogenic, mitochondrial, and thermogenic gene programs of beige adipocytes, thus suppressing their differentiation ability, mitochondrial activity, and thermogenic response. Importantly, exposure to AgNPs in mice suppresses browning gene programs in subcutaneous fat, leading to decreased energy expenditure and increased adiposity in mice. Mechanistically, we found that AgNPs increase reactive oxidative species (ROS) levels and specifically activate MAPK-ERK signaling in beige adipocytes. The negative impacts of AgNPs on beige adipocytes can be ameliorated by antioxidant or ERK inhibitor FR180204 treatment.

Conclusions

Taken together, these results revealed an unexpected role of AgNPs in promoting adiposity through the inhibition of beige adipocyte differentiation and functionality, possibly by disrupting ROS homeostasis and ERK phosphorylation. Future assessments on the health risk of AgNPs applications and their safe dosages are warranted.

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The environmental pollutant AgNPs promote adiposity and metabolic disorders in mice.

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AgNPs suppress beige adipocytes differentiation and functionality both in vitro and in vivo.

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AgNPs increase ROS levels and specifically activate ERK signaling in beige adipocytes.

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The negative impacts of AgNPs can be ameliorated by antioxidant or ERK inhibitor.

Neurotoxicity of Nanomaterials: An Up-to-Date Overview

The field of nanotechnology, through which nanomaterials are designed, characterized, produced, and applied, is rapidly emerging in various fields, including energy, electronics, food and agriculture, environmental science, cosmetics, and medicine. The most common biomedical applications of nanomaterials involve drug delivery, bioimaging, and gene and cancer therapy. Since they possess unique properties which are different than bulk materials, toxic effects and long-term impacts on organisms are not completely known. Therefore, the purpose of this review is to emphasize the main neurotoxic effects induced by nanoparticles, liposomes, dendrimers, carbon nanotubes, and quantum dots, as well as the key neurotoxicology assays to evaluate them.

Cytotoxicity and Transcriptomic Analysis of Silver Nanoparticles in Mouse Embryonic Fibroblast Cells

The rapid development of nanotechnology has led to the use of silver nanoparticles (AgNPs) in biomedical applications, including antibacterial, antiviral, anti-inflammatory, and anticancer therapies. The molecular mechanism of AgNPs-induced cytotoxicity has not been studied thoroughly using a combination of cellular assays and RNA sequencing (RNA-Seq) analysis. In this study, we prepared AgNPs using myricetin, an anti-oxidant polyphenol, and studied their effects on NIH3T3 mouse embryonic fibroblasts as an in vitro model system to explore the potential biomedical applications of AgNPs. AgNPs induced loss of cell viability and cell proliferation in a dose-dependent manner, as evident by increased leakage of lactate dehydrogenase (LDH) from cells. Reactive oxygen species (ROS) were a potential source of cytotoxicity. AgNPs also incrementally increased oxidative stress and the level of malondialdehyde, depleted glutathione and superoxide dismutase, reduced mitochondrial membrane potential and adenosine triphosphate (ATP), and caused DNA damage by increasing the level of 8-hydroxy-2′-deoxyguanosine and the expressions of the p53 and p21 genes in NIH3T3 cells. Thus, activation of oxidative stress may be crucial for NIH3T3 cytotoxicity. Interestingly, gene ontology (GO) term analysis revealed alterations in epigenetics-related biological processes including nucleosome assembly and DNA methylation due to AgNPs exposure. This study is the first demonstration that AgNPs can alter bulk histone gene expression. Therefore, our genome-scale study suggests that the apoptosis observed in NIH3T3 cells treated with AgNPs is mediated by the repression of genes required for cell survival and the aberrant enhancement of nucleosome assembly components to induce apoptosis.