Effect of silver nanoparticles on the standard soil arthropod Folsomia candida (Collembola) and the eukaryote model organism Saccharomyces cerevisiae

Presence of microplastics enhanced the toxicity of silver nanoparticles on the collembolan Folsomia candida

There is growing interest in interactions of microplastics (MPs) with other pollutants. However, there is limited understanding of the combined effects of MPs and silver nanoparticles (AgNPs) on nontarget soil organisms. This work aimed to examine the effects of exposure to various AgNPs' concentrations alone (0, 0.1, 1, 10, 100, 1000 mg kg-1, 50 nm) and in combination with polyvinyl chloride microplastics (PVC MPs, 80-250 μm) at 0.1% concentration for 28 days on reproduction, Ag accumulation, C/N ratio, and isotopic fractionation of the standard soil fauna collembolan Folsomia candida. Results showed that compared to the AgNPs exposure alone, the presence of MPs significantly reduced reproduction by 51.4% and markedly increased Ag content in collembolans by 87.7% at 1000 mg kg-1 AgNPs, which evidenced a synergistic effect. Co-exposure to MPs and AgNPs resulted in a noticeable reduction in the C/N ratio in F. candida body tissues by 9.90% and 5.27% at 1 and 10 mg kg-1 AgNPs, respectively, showing additive and synergistic effects. Additionally, this co-exposure altered stable isotope fractionation, with the highest increments of δ15N by 32.3% and inhibition of δ13C by 2.62%, demonstrating the turnover of nutrients shift in the collembolan tissues. Collectively, this study demonstrates that con-current exposure to environmentally relevant concentration of MPs and relatively high doses of AgNPs synergistically induces toxic effects on F. candida, leading to Ag accumulation and reproduction decline. These findings imply that MPs could alter collembolans' responses to AgNPs exposure, potentially enhancing the metal ions' bioavailability in soil environments and posing ecotoxicological threats to soil-dwelling organisms.

Impact of silver ions and silver nanoparticles on biochemical parameters and antioxidant enzyme modulations in Saccharomyces cerevisiae under co-exposure to static magnetic field: a comparative investigation

The increase in simultaneous exposure to magnetic fields and other hazardous compounds released from industrial applications poses multiple stress conditions on the ecosystems and public human health. In this work, we investigated the effects of co-exposure to a static magnetic field (SMF) and silver ions (AgNO3) on biochemical parameters and antioxidant enzyme activities in the yeast Saccharomyces cerevisiae. Sub-chronic exposure to AgNO3 (0.5 mM) for 9 h resulted in a significant decrease in antioxidant enzyme activity, including glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and glutathione transferase (GST). The total glutathione (GSH) level increased in yeast cells exposed to Ag. Additionally, a notable elevation in malondialdehyde (MDA) levels and protein carbonyl content was observed in both the AgNP and AgNO3 groups compared to the control group. Interestingly, the SMF alleviated the oxidative stress induced by silver nitrate, normalizing antioxidant enzyme activities by reducing cellular ROS formation, MDA levels, and protein carbonylation (PCO) concentrations.

Oxidative stress related effect of xenobiotics on eukaryotic model organism, Saccharomyces cerevisiae

Ecotoxicological assays have traditionally focused on the effects of chemicals at the individual level by exploiting mortality and reproduction as endpoints. Although these two parameters are ecologically relevant, they rarely provide information regarding the elemental toxic mechanisms. Obviously, the number of xenobiotics used has been rapidly increased. Thus, any established measurement that shortens the actual outcome and, simultaneously provides information about toxic mechanisms is desirable. This research focused on the study of oxidative stress response as a biomarker in the eukaryotic model organism, Saccharomyces cerevisiae. For this, yeast cells were exposed to a set of selected environmentally relevant chemicals via different approaches, including cellular diagnostics, gene expression analysis and chemo-genetic screening. The results demonstrated that at the cellular level, model organisms reacted to different chemicals in distinct manner. For each xenobiotic, the correlation between toxic response of molecular and cellular levels are presented. Namely, the expression of target genes after chemical exposure affected the cellular alteration as evidenced by an elevated level of superoxide dismutase and a reduced amount of glutathione. Furthermore, the results derived from chemo-genetic screening, in which mutants lacking of gene of interest were employed, exhibited more susceptibility to test chemicals in comparison to the wildtype. The response of oxidative stress upon chemical exposure in budding yeast from this study is potentially useful for an establishment of a proper bio-test system which can eventually be linked to adverse effects at an individual level in higher eukaryotes.

Antibacterial and antibiofilm effects of Pseudomonas aeruginosa derived outer membrane vesicles against Streptococcus mutans

Antimicrobial resistance (AMR) is a serious and most urgent global threat to human health. AMR is one of today's biggest difficulties in the health system and has the potential to harm people at any stage of life, making it a severe public health issue. There must be fewer antimicrobial medicines available to treat diseases given the rise in antibiotic-resistant organisms. If no new drugs are created or discovered, it is predicted that there won't be any effective antibiotics accessible by 2050. In most cases, Streptococcus increased antibiotic resistance by forming biofilms, which account for around 80 % of all microbial infections in humans. This highlights the need to look for new strategies to manage diseases that are resistant to antibiotics. Therefore, development alternative, biocompatible and high efficacy new strategies are essential to overcome drug resistance. Recently, bacterial derived extracellular vesicles have been applied to tackle infection and reduce the emergence of drug resistance. Therefore, the objective of the current study was designed to assess the antibacterial and antibiofilm potential of outer membrane vesicles (OMVs) derived from Pseudomonas aeruginosa againstStreptococcus mutans. According to the findings of this investigation, the pure P. aeruginosa outer membrane vesicles (PAOMVs) display a size of 100 nm. S. mutans treated with PAOMVs showed significant antibacterial and antibiofilm activity. The mechanistic studies revealed that PAOMVs induce cell death through excessive generation of reactive oxygen species and imbalance of redox leads to lipid peroxidation, decreased level of antioxidant markers including glutathione, superoxide dismutase and catalase. Further this study confirmed that PAOMVs significantly impairs metabolic activity through inhibiting lactate dehydrogenase activity (LDH), adenosine triphosphate (ATP) production, leakage of proteins and sugars. Interestingly, combination of sub-lethal concentrations of PAOMVs and antibiotics enhances cell death and biofilm formation of S. mutans. Altogether, this work, may serve as an important basis for further evaluation of PAOMVs as novel therapeutic agents against bacterial infections.

Multidimensional applications and potential health implications of nanocomposites

This study reviews the concept, classifications, and techniques involved in the synthesis of nanocomposites. The environmental and health implications of nanoparticles and composite materials were detailed, as well as the applications of nanocomposites in water remediation, antibacterial application, and printed circuit boards. The study gave insights into the challenges of water pollution treatment and provided a broad list of nanocomposites that have been explored for water remediation. Moreover, the emergence of multi-drug resistance to many antibiotics has made current antibiotics inadequate in the treatment of disease. This has engineered the development of alternative strategies in the drug industries for the production of effective therapeutic agents, comprising nanocomposites with antibacterial agents. The new therapeutic agents known as nanoantibiotics are more efficient and have paved the way to handle the challenges of antibiotic resistance. In printed circuit boards, nanocomposites have shown promising applications because of their distinct mechanical, thermal, and electrical characteristics. The uniqueness of the write-up is that it provides a broad explanation of the concept, synthesis, application, toxicity, and harmful effects of nanocomposites. Thus, it will provide all-inclusive awareness to readers to identify research gaps and motivate researchers to synthesize novel nanocomposites for use in various fields.

Quantification of silver nanoparticle interactions with yeast Saccharomyces cerevisiae studied using single-cell ICP-MS

Silver nanoparticles (AgNPs) have been used in many fields due to their anticancer, antimicrobial, and antiviral potential. Single-cell ICP-MS (SC-ICP-MS) is an emerging technology that allows for the rapid characterization and quantification of a metal analyte across a cell population in a single analysis. In this study, a new rapid and sensitive SC-ICP-MS method was developed to quantitatively study the interactions of AgNPs with yeast Saccharomyces cerevisiae. The method can quantify the cell concentration, silver concentration per cell, and profile the nanoparticle distribution in a yeast cell population. AgNP dosing time, concentration, and AgNP size were quantitatively evaluated for their effects on AgNP-yeast cell interactions. The results showed that the initial uptake of AgNPs was rapid and primarily driven by the mass of Ag per cell. The optimal dosing particle concentrations for highest uptake were approximately 1820, 1000, and 300 AgNPs/cell for 10, 20, and 40 nm AgNPs, respectively. Furthermore, this study also validated a washing method for the application to a microorganism for the first time and was used to quantitatively determine the amount of cell surface-adsorbed AgNPs and intracellular AgNPs. These results indicated that the mass (Ag in ag/cell) ratios of intracelluar vs cell surface-adsorbed AgNPs were similar for different AgNP sizes. This high throughput and ultrasensitive SC-ICP-MS method is expected to have many potential applications, such as optimization of methods for green synthesis of AgNPs, nanotoxicity studies, and drug delivery. This is the first quantification study on the interactions of AgNPs and S. cerevisiae using SC-ICP-MS.

Reactive Oxygen Species Detection Using Fluorescence in Enchytraeus crypticus-Method Implementation through Ag NM300K Case Study

An imbalance between reactive oxygen species (ROS) and antioxidants in a living organism results in oxidative stress. Measures of such imbalance can be used as a biomarker of stress in ecotoxicology. In this study, we implemented the ROS detection method based on the oxidant-sensing probe dichloro-dihydro-fluorescein diacetate (DCFH-DA), detected by fluorescence microscopy, in Enchytraeus crypticus adults and cocoons, i.e., also covering the embryo stage. Hydrogen peroxide (H2O2), a well-known ROS inducer, was used both to optimize the method and as positive control. Implementation was successful, and the method was used to assess ROS formation in E. crypticus cocoons and adults when exposed to the reference silver nanomaterial Ag NM300K, at two effect concentrations (EC20 and EC50) for both hatching and reproduction over 3 and 7 days. The measured ROS levels varied with time, concentration, and developmental stage, with higher levels detected in adults compared with cocoons. In cocoons, ROS levels were higher at the EC20 than the EC50, which could be explained by non-monotonic concentration-response curve for hatching and reproduction, as previously observed. The increase in ROS levels at day 3 preceded the oxidative damage, as reported to occur later (day 7) in adults. The DCFH-DA method was successfully implemented here and can be further used as a new tool to detect ROS formation in E. crypticus, especially after short-term exposure to chemicals, including nanomaterials. We recommend the use of 3 and 7 days in the exposure design for this assessment.

Post COVID-19 pandemic: Biofragmentation and soil ecotoxicological effects of microplastics derived from face masks

Because of the COVID-19 pandemic, used face masks have increasingly littered the environment and are causes for concern since they are commonly made of plastics such as polypropylene. Understanding production of microplastics from face masks is essential for predicting the post COVID-19 pandemic impact on the soil ecosystem. We investigated the generation of nanofibers from meltblown face mask filters (MB filters) and their adverse effects on soil species, particularly the earthworm and springtail. Results of MB filter soil bioassays at a high concentration (1000 mg/kg dry soil) suggest inhibited reproduction and stunted growth in springtails, decreased intracellular esterase activity in earthworm coelomocytes, and inhibited spermatogenesis in male earthworm reproductive tissues. Moreover, it was estimated that generation of nanofibers from microfibers and fragments of MB filters might occur in the soil ecosystem post COVID-19. This study does not oppose the use of face masks but aims to encourage appropriate disposal of the masks. Preservation of human health and the ecosystem should be prioritized even amidst the COVID-19 pandemic.

Transcriptome Profile Alterations with Carbon Nanotubes, Quantum Dots, and Silver Nanoparticles: A Review

Next-generation sequencing (NGS) technology has revolutionized sequence-based research. In recent years, high-throughput sequencing has become the method of choice in studying the toxicity of chemical agents through observing and measuring changes in transcript levels. Engineered nanomaterial (ENM)-toxicity has become a major field of research and has adopted microarray and newer RNA-Seq methods. Recently, nanotechnology has become a promising tool in the diagnosis and treatment of several diseases in humans. However, due to their high stability, they are likely capable of remaining in the body and environment for long periods of time. Their mechanisms of toxicity and long-lasting effects on our health is still poorly understood. This review explores the effects of three ENMs including carbon nanotubes (CNTs), quantum dots (QDs), and Ag nanoparticles (AgNPs) by cross examining publications on transcriptomic changes induced by these nanomaterials.

Tetrahedral DNA nanostructure improves transport efficiency and anti-fungal effect of histatin 5 against Candida albicans

OBJECTIVES

Anti-microbial peptides (AMPs) have been comprehensively investigated as a novel alternative to traditional antibiotics against microorganisms. Meanwhile, Tetrahedral DNA nanostructures (TDNs) have gained attention in the field of biomedicine for their premium biological effects and transportation efficiency as delivery vehicles. Hence, in this study, TDN/Histatin 5 (His-5) was synthesized and the transport efficiency and anti-fungal effect were measured to evaluate the promotion of His-5 modified by TDNs.

MATERIALS AND METHODS

Tetrahedral DNA nanostructures/His-5 complex was prepared via electrostatic attraction and characterized by transmission electron microscopy (TEM), polyacrylamide gel electrophoresis (PAGE), dynamic light scattering (DLS) and electrophoretic light scattering (ELS). The anti-fungal effect of the TDN/His-5 complex was evaluated by determining the growth curve and colony-forming units of C. albicans. The morphological transformation of C. albicans was observed by light microscope and scanning electron microscope (SEM). Immunofluorescence was performed, and potassium efflux was detected to mechanistically demonstrate the efficacy of TDN/His-5.

RESULTS

The results showed that Histatin 5 modified by TDNs had preferable stability in serum and was effectively transported into C. albicans, leading to the increased formation of intracellular reactive oxygen species, higher potassium efflux and enhanced anti-fungal effect against C. albicans.

CONCLUSIONS

Our study showed that TDN/His-5 was synthesized successfully. And by the modification of TDNs, His-5 showed increased transport efficiency and improved anti-fungal effect.

Silver nanoparticles: Toxicity in model organisms as an overview of its hazard for human health and the environment

Silver nanoparticles (AgNPs) have attracted remarkable attention due to their powerful antimicrobial action as well as their particular physicochemical properties. This has led to their application in a wide variety of products with promising results. However, their interaction with the environment and toxicity in live terrestrial or aquatic organisms is still a matter of intense debate. More detailed knowledge is still required about the toxicity of AgNPs, their possible uptake mechanisms and their adverse effects in live organisms. Several studies have reported the interactions and potential negative effects of AgNPs in different organisms. In this review, we report and discuss the current state of the art and perspectives for the impact of AgNPs on different organisms present in the environment. Recent progress in interpreting uptake, translocation and accumulation mechanisms in different organisms and/or living animals are discussed, as well as the toxicity of AgNPs and possible tolerance mechanisms in live organisms to cope with their deleterious effects. Finally, we discuss the challenges of accurate physicochemical characterization of AgNPs and their ecotoxicity in environmentally realistic conditions such as soil and water media.

Inhibitory effect of metals on animal and plant glutathione transferases

Glutathione transferases (GSTs) represent a widespread enzyme superfamily in eukaryotes and prokaryotes catalyzing different reactions with endogenous and xenobiotic substrates such as organic pollutants. The latter are often found together with metal contamination in the environment. Besides performing of essential functions, GSTs protect cells by conjugation of glutathione with various reactive electrophiles. The interference of toxic metals with this functionality of GSTs may have unpredictable toxicological consequences for the organisms. In this review results from the recent literature are summarized and discussed describing the ability of metals to inhibit intracellular detoxification processes in animals and plants.

Silver nanoparticles induce reactive oxygen species-mediated cell cycle delay and synergistic cytotoxicity with 3-bromopyruvate in Candida albicans, but not in Saccharomyces cerevisiae

Background: Silver nanoparticles (AgNPs) inhibit the proliferation of various fungi; however, their mechanisms of action remain poorly understood. To better understand the inhibitory mechanisms, we focused on the early events elicited by 5 nm AgNPs in pathogenic Candida albicans and non-pathogenic Saccharomyces cerevisiae. Methods: The effect of 5 nm and 100 nm AgNPs on fungus cell proliferation was analyzed by growth kinetics monitoring and spot assay. We examined cell cycle progression, reactive oxygen species (ROS) production, and cell death using flow cytometry. Glucose uptake was assessed using tritium-labeled 2-deoxyglucose. Results: The growth of both C. albicans and S. cerevisiae was suppressed by treatment with 5 nm AgNPs but not with 100 nm AgNPs. In addition, 5 nm AgNPs induced cell cycle arrest and a reduction in glucose uptake in both fungi after 30 minutes of culture in a dose-dependent manner (P<0.05). However, in C. albicans only, an increase in ROS production was detected after exposure to 5 nm AgNPs. Concordantly, an ROS scavenger blocked the effect of 5 nm AgNPs on the cell cycle and glucose uptake in C. albicans only. Furthermore, the growth-inhibition effect of 5 nm AgNPs was not greater in S. cerevisiae mutant strains deficient in oxidative stress response genes than it was in wild type. Finally, 5 nm AgNPs together with a glycolysis inhibitor, 3-bromopyruvate, synergistically enhanced cell death in C. albicans (P<0.05) but not in S. cerevisiae. Conclusion: AgNPs exhibit antifungal activity in a manner that may or may not be ROS dependent, according to the fungal species. The combination of AgNPs with 3-bromopyruvate may be more useful against infection with C. albicans.

Effects of AgNPs on the Snail Biomphalaria glabrata: Survival, Reproduction and Silver Accumulation

Silver nanoparticles (AgNPs) are used intensively in medical and industrial applications. Environmental concerns have arisen from the potential release of this material into aquatic ecosystems. The aims of this research were to evaluate the potential accumulation of silver in the whole body of organisms and analyze the effects of AgNPs on the survival and reproduction of the snail Biomphalaria glabrata. Results show slow acute toxicity with a 10-day LC₅₀ of 18.57 mg/L and an effective decrease in the eggs and egg clutches per organism exposed to tested concentrations. Based on these data, the No Observed Effect Concentration (NOEC) observed was <1 mg/L for snail reproduction. For silver accumulation, we observed that uptake was faster than elimination, which was very slow and still incomplete 35 days after the end of the experiment. However, the observed accumulation was not connected with a concentration/response relationship, since the amount of silver was not equivalent to a higher reproductive effect. The data observed show that AgNPs are toxic to B. glabrata, and suggest that the snail has internal mechanisms to combat the presence of Ag in its body, ensuring survival and reduced reproduction and showing that the species seems to be a potential indicator for Ag presence in contaminated aquatic ecosystems.

Synthesis of biogenic silver nanoparticles using Althaea officinalis as reducing agent: evaluation of toxicity and ecotoxicity

Silver nanoparticles (AgNPs) are known mainly because of their bactericidal properties. Among the different types of synthesis, there is the biogenic synthesis, which allows the synergy between the nanocomposites and substances from the organism employed for the synthesis. This study describes the synthesis of AgNPs using infusion of roots (AgNpR) and extract (AgNpE) of the plant Althaea officinalis. After the synthesis through reduction of silver nitrate with compounds of A. officinalis, physico-chemical analyzes were performed by UV-Vis spectroscopy, nanoparticles tracking analysis (NTA), dynamic light scattering (DLS) and scanning electron microscopy (SEM). Toxicity was evaluated through Allium cepa assay, comet test with cell lines, cell viability by mitochondrial activity and image cytometry and minimal inhibitory concentration on pathogenic microorganisms. Biochemical analyzes (CAT - catalase, GPx - glutathione peroxidase e GST - glutationa S-transferase) and genotoxicity evaluation in vivo on Zebrafish were also performed. AgNpE and AgNpR showed size of 157 ± 11 nm and 293 ± 12 nm, polydispersity of 0.47 ± 0.08 and 0.25 ± 0.01, and zeta potential of 20.4 ± 1.4 and 26.5 ± 1.2 mV, respectively. With regard to toxicity, the AgNpE were the most toxic when compared with AgNpR. Biochemical analyzes on fish showed increase of CAT activity in most of the organs, whereas GPx showed few changes and the activity of GST decreased. Also regarding to bactericidal activity, both nanoparticles were effective, however AgNpR showed greater activity. Althaea officinalis can be employed as reducing agent for the synthesis of silver nanoparticles, although it is necessary to consider its potential toxicity and ecotoxicity.

Effects of Silver Nanoparticles on Multiple Drug-Resistant Strains of Staphylococcus aureus and Pseudomonas aeruginosa from Mastitis-Infected Goats: An Alternative Approach for Antimicrobial Therapy

Recently, silver nanoparticles (AgNPs) have been widely used in various applications as antimicrobial agents, anticancer, diagnostics, biomarkers, cell labels, and drug delivery systems for the treatment of various diseases. Microorganisms generally acquire resistance to antibiotics through the course of antibacterial therapy. Multi-drug resistance (MDR) has become a growing problem in the treatment of infectious diseases, and the widespread use of broad-spectrum antibiotics has resulted in the development of antibiotic resistance by numerous human and animal bacterial pathogens. As a result, an increasing number of microorganisms are resistant to multiple antibiotics causing continuing economic losses in dairy farming. Therefore, there is an urgent need for the development of alternative, cost-effective, and efficient antimicrobial agents that overcome antimicrobial resistance. Here, AgNPs synthesized using the bio-molecule quercetin were characterized using various analytical techniques. The synthesized AgNPs were highly spherical in shape and had an average size of 11 nm. We evaluated the efficacy of synthesized AgNPs against two MDR pathogenic bacteria, namely, Pseudomonas aeruginosa and Staphylococcus aureus, which were isolated from milk samples produced by mastitis-infected goats. The minimum inhibitory concentrations (MICs) of AgNPs against P. aeruginosa and S. aureus were found to be 1 and 2 μg/mL, respectively. Our findings suggest that AgNPs exert antibacterial effects in a dose- and time-dependent manner. Results from the present study demonstrate that the antibacterial activity of AgNPs is due to the generation of reactive oxygen species (ROS), malondialdehyde (MDA), and leakage of proteins and sugars in bacterial cells. Results of the present study showed that AgNP-treated bacteria had significantly lower lactate dehydrogenase activity (LDH) and lower adenosine triphosphate (ATP) levels compared to the control. Furthermore, AgNP-treated bacteria showed downregulated expression of glutathione (GSH), upregulation of glutathione S-transferase (GST), and downregulation of both superoxide dismutase (SOD) and catalase (CAT). These physiological and biochemical measurements were consistently observed in AgNP-treated bacteria, thereby suggesting that AgNPs can induce bacterial cell death. Thus, the above results represent conclusive findings on the mechanism of action of AgNPs against different types of bacteria. This study also demonstrates the promising use of nanoparticles as antibacterial agents for use in the biotechnology and biomedical industry. Furthermore, this study is the first to propose the mode of action of AgNPs against MDR pathogens isolated from goats infected with subclinical mastitis.