Hormesis effects of silver nanoparticles at non-cytotoxic doses to human hepatoma cells

The role of silver nanoparticles in yellow lupine (Lupinus luteus L.) defense response to Fusarium oxysporum f.sp. lupini

This study presents the influence of silver nanoparticles (AgNPs) on the growth of yellow lupine (Lupinus luteus L.cv. Diament and Lupinus luteus L.cv. Mister), and some metabolic reactions triggered by AgNPs during the seed germination stage and development of the seedling. Also, the role of AgNPs in defense mechanisms of the above of yellow lupine varieties against hemibiotrofic patogen Fusarium oxysporum f.sp. lupini. AgNPs enhanced the growth of yellow lupine seedlings, particularly root length and fresh biomass. Furthermore, AgNPs triggered defense-related phytohormones, such as abscisic acid (ABA), jasmonates (JA/MeJA), and salicylic acid (SA), which were involved in defense response of yellow lupine against F. oxysporum infection. The application of AgNPs significantly enhanced the growth of yellow lupine seedlings, increasing root length by over 400% and fresh biomass by 183% compared to the control. Moreover, AgNPs also significantly triggered an important defense-related phytohormone ABA, which increased by 103- and 38-times in Diament and Mister varieties, respectively. AgNPs influenced soluble sugar levels, such as sucrose and fructose, in yellow lupine, which may be related to defense mechanisms. The treatment with AgNPs induced a hormetic effect, where the roots of seedlings exhibited increased growth and defense responses at low concentrations. The level of gibberellic acid (GA) increased by 556% and 297% in AgNP-pretreated embryo axes of Diament and Mister varieties, respectively. Sugar levels, such as sucrose and fructose, were also influenced by AgNPs. In Diament variety, sucrose and fructose levels increased by 60% and 146%, respectively. However, F. oxysporum infection caused a strong decline in sugar levels. Overall, the study suggests that AgNPs can be used to enhance plant growth and defense against pathogens.

Impact of surface chemistry of upconversion nanoparticles on time-dependent cytotoxicity in non-cancerous epithelial cells

The application of upconversion nanoparticles (UCNPs) for cell and tissue analysis requires a comprehensive understanding of their interactions with biological entities to prevent toxicity or harmful effects. Whereas most studies focus on cancer cells, this work addresses non-cancerous cells with their regular in vitro physiology. Since it is generally accepted that surface chemistry largely determines biocompatibility in general and uptake of nanomaterials in particular, two bilayer surface coatings with different surface shielding properties have been studied: (i) a phospholipid bilayer membrane (PLM) and (ii) an amphiphilic polymer (AP). Both surface modifications are applied to (12-33) nm core-shell UCNPs NaYF4(Yb, Er)@NaYF4, ensuring colloidal stability in biological media. The impact of UCNPs@AP and UCNPs@PLM on non-cancerous epithelial-like kidney cells in vitro was found to differ significantly. UCNPs@PLM did not exhibit any measurable effect on cell physiology, even with prolonged exposure. In contrast, UCNPs@AP caused changes in cell morphology and induced cell-death after approximately 30 h. These variations in toxicity are attributed to the distinct chemical stability of these particles, which likely influences their intracellular disintegration.

Decelerated skin aging effect of rubber (Hevea brasiliensis) seed oil in cell culture assays

Rubber seeds, the abundant by-products of rubber tree (Hevea brasiliensis), have been studied for sustainable utilization. Nevertheless, there is no information available regarding activity against skin aging. The study aimed to prepare rubber seed oil (RSO) and evaluate fatty acid compositions by gas chromatography - mass spectrometry (GC/MS), linamarin contamination by ultra-high performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS). Additionally, cytotoxicity assay and anti-skin aging activities, including cell proliferating stimulation, cellular antioxidant, collagen stimulation, and matrix metalloproteinase-2 (MMP-2) inhibition, were analyzed in immortalized human skin keratinocytes (HaCaT cells) and human dermal fibroblasts. RSO was pale-yellow oily liquid with an extraction yield of 35.79 ± 0.52%. Principal fatty acids were comprised of oleic (43.37 ± 0.76%), linoleic (38.49 ± 0.81%), palmitic (11.47 ± 0.12%), and stearic (6.66 ± 0.05%) acids. Linamarin contamination was not detected in 100 µg/mL RSO, demonstrating the absence of a cyanogenic glucoside. Non-cytotoxic concentrations of RSO in both cells were in the range of 0.0001-0.1 mg/mL. Activities of RSO against skin aging included the cell proliferating stimulation, the antioxidant activity, the collagen stimulation, and the MMP-2 suppression at mRNA expression level and enzymatic activity. Study results have suggested that rubber seeds can probably be employed as a promising ingredient in the preparations designed for deceleration of skin aging.

Molecular mechanism of nanomaterials induced liver injury: A review

The unique physicochemical properties inherent to nanoscale materials have unveiled numerous potential applications, spanning beyond the pharmaceutical and medical sectors into various consumer industries like food and cosmetics. Consequently, humans encounter nanomaterials through diverse exposure routes, giving rise to potential health considerations. Noteworthy among these materials are silica and specific metallic nanoparticles, extensively utilized in consumer products, which have garnered substantial attention due to their propensity to accumulate and induce adverse effects in the liver. This review paper aims to provide an exhaustive examination of the molecular mechanisms underpinning nanomaterial-induced hepatotoxicity, drawing insights from both in vitro and in vivo studies. Primarily, the most frequently observed manifestations of toxicity following the exposure of cells or animal models to various nanomaterials involve the initiation of oxidative stress and inflammation. Additionally, we delve into the existing in vitro models employed for evaluating the hepatotoxic effects of nanomaterials, emphasizing the persistent endeavors to advance and bolster the reliability of these models for nanotoxicology research.

Nanoparticles: Taking a Unique Position in Medicine

The human nature of curiosity, wonder, and ingenuity date back to the age of humankind. In parallel with our history of civilization, interest in scientific approaches to unravel mechanisms underlying natural phenomena has been developing. Recent years have witnessed unprecedented growth in research in the area of pharmaceuticals and medicine. The optimism that nanotechnology (NT) applied to medicine and drugs is taking serious steps to bring about significant advances in diagnosing, treating, and preventing disease-a shift from fantasy to reality. The growing interest in the future medical applications of NT leads to the emergence of a new field for nanomaterials (NMs) and biomedicine. In recent years, NMs have emerged as essential game players in modern medicine, with clinical applications ranging from contrast agents in imaging to carriers for drug and gene delivery into tumors. Indeed, there are instances where nanoparticles (NPs) enable analyses and therapies that cannot be performed otherwise. However, NPs also bring unique environmental and societal challenges, particularly concerning toxicity. Thus, clinical applications of NPs should be revisited, and a deep understanding of the effects of NPs from the pathophysiologic basis of a disease may bring more sophisticated diagnostic opportunities and yield more effective therapies and preventive features. Correspondingly, this review highlights the significant contributions of NPs to modern medicine and drug delivery systems. This study also attempted to glimpse the future impact of NT in medicine and pharmaceuticals.

Proteomic Response of Aedes aegypti Larvae to Silver/Silver Chloride Nanoparticles Synthesized Using Bacillus thuringiensis subsp. israelensis Metabolites

Simple Summary

Aedes aegypti is a vector of important mosquito-borne diseases. Green synthesized nanoparticles (NPs) have been used to control the larvae of mosquitoes including A. aegypti. However, the molecular responses of A. aegypti larvae to green synthesized NPs remain unexplored. This work analyzed protein expression in A. aegypti larvae in response to treatment using green synthesized silver/silver chloride nanoparticles (Ag/AgCl NPs) based on two-dimensional polyacrylamide gel electrophoresis. Fifteen differentially expressed protein spots were selected for identification using mass spectrometry. The results showed that the six upregulated proteins in A. aegypti larvae responsible for green synthesized Ag/AgCl NP treatment were involved in mitochondrial dysfunction, DNA and protein damage, inhibition of cell proliferation, and cell apoptosis, implying the modes of actions of Ag/AgCl NPs. This finding has provided greater insight into the possible mechanisms of green synthesized Ag/AgCl NPs on the control of A. aegypti larvae.

Abstract

Silver/silver chloride nanoparticles (Ag/AgCl NPs) are an alternative approach to control the larvae of Aedes aegypti, a vector of mosquito-borne diseases. However, the molecular mechanisms of Ag/AgCl NPs to A. aegypti have not been reported. In this work, Ag/AgCl NPs were synthesized using supernatant, mixed toxins from Bacillus thuringiensis subsp. israelensis (Bti), and heterologously expressed Cry4Aa and Cry4Ba toxins. The images from scanning electron microscopy revealed that the Ag/AgCl NPs were spherical in shape with a size range of 25–100 nm. The larvicidal activity against A. aegypti larvae revealed that the Ag/AgCl NPs synthesized using the supernatant of Bti exhibited higher toxicity (LC₅₀ = 0.133 μg/mL) than the Ag/AgCl NPs synthesized using insecticidal proteins (LC₅₀ = 0.148–0.217 μg/mL). The proteomic response to Ag/AgCl NPs synthesized using the supernatant of Bti in A. aegypti larvae was compared to the ddH₂O-treated control. Two-dimensional gel electrophoresis analysis revealed 110 differentially expressed proteins, of which 15 were selected for identification using mass spectrometry. Six upregulated proteins (myosin I heavy chain, heat shock protein 70, the F₀F₁-type ATP synthase beta subunit, methyltransferase, protein kinase, and condensin complex subunit 3) that responded to Ag/AgCl NP treatment in A. aegypti were reported for NP treatments in different organisms. These results suggested that possible mechanisms of action of Ag/AgCl NPs on A. aegypti larvae are: mitochondrial dysfunction, DNA and protein damage, inhibition of cell proliferation, and cell apoptosis. The findings from this work provide greater insight into the action of green synthesized Ag/AgCl NPs on the control of A. aegypti larvae.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.

Differential toxicity of abrin in human cell lines of different organ origin

Abrus precatorius is a highly toxic seed containing the poison abrin. Similar in properties to ricin, this toxin binds to ribosomes causing cessation of protein synthesis and cell death. With an estimated human lethal dose of 0.1-1 μg/kg, it has been the cause of fatalities due to accidental and intentional ingestion. In present study, we profiled seven human cell lines of different organ origin, for their sensitivity against abrin toxicity. These cell lines are, A549, COLO 205, HEK 293, HeLa, Hep G2, Jurkat, SH-SY5Y and derived from lung, intestine, kidney, cervix, liver, immune and nervous system respectively. MTT, NR, CVDE and LDH assays have been used to determine their response against abrin toxin. Among these cell lines A549 was the most sensitive cell line while Hep G2 was found least sensitive cell lines. Hep G2 cells are shown to have mitochondrial resistance and delayed generation of oxidative stress compared to A549 cells. Remarkable variation in sensitivity against abrin toxicity prompted the evaluation of Bcl2, Bax and downstream caspases in both cells. Difference in Bcl2 level has been shown to play important role in variable sensitivity. Findings of present study are helpful for selection of suitable cellular model for toxicity assessment and antidote screening.

Productivity performance of peach trees, insecticidal and antibacterial bioactivities of leaf extracts as affected by nanofertilizers foliar application

The current study was performed on eight years old peach (Prunus persica L. Batsch) trees cv. Florida prince to study the influence of spraying of commercial nano fertilizer on vegetative growth, pollen grain viability, yield, and fruit quality of the "Florida prince" peach cultivar. Furthermore, extracts from the nanofertilizer treated leaves were studied for their bioactivity as insecticidal or bactericidal activities against some stored grain insects and plant bacterial pathogens. Seventy uniform peach trees were sprayed three time as follow: before flowering; during full bloom, and one month later in addition using the water as a control. Commercial silver particales (Ag NPs) at 10, 12.5, and 15 mL/L and zinc particales (Zn NPs) at 2.5, 5 and 7.5 mL/L as recommended level in a randomized complete block design in ten replicates/trees. Spraying Ag NP at 15 mL/L increased shoot diameter, leaf area, total chlorophyll, flower percentage, fruit yield and fruit physical and chemical characteristics, followed by Ag NPs at 12.5 mL/L and Zn NPs at 7.5 mL/L. Moreover, Zn and Ag NPs caused a highly significant effect on pollen viability. Different type of pollen aberrations were detected by Zn NPs treatment. The commercial Ag NPs showed a high increase in pollen viability without any aberrations. The Ag NPs significantly increased the pollen size, and the spores also increased and separated in different localities, searching about the egg for pollination and fertilization. Peach leaves extract was examined for their insecticidal activity against rice weevil (Sitophilus oryzea L.) and the lesser grain borer (Rhyzopertha dominica, Fabricius) by fumigation method. The antibacterial activity of all treatments was also performed against molecularly identified bacteria. Ag NPs treated leaves extract at concentration 3000 µg/mL were moderate sufficient to inhibit all the bacterial isolates with inhibition zone (IZ) ranged 6-8.67 mm with high efficiency of acetone extracts from leaves treated with Ag NPs compared with Zn NPs. Also, S. oryzae was more susceptible to acetone extracts from leaves treated with both nanomaterials than R. dominica.

The distinct effect of titanium dioxide nanoparticles in primary and immortalized cell lines

The titanium dioxide nanoparticles (NPs) have been applied to biomedical, pharmaceutical, and food additive fields. However, the effect on health and the environment are conflicting; thus, it has been reviewing several times. In this context, establishing standard robust protocols for detecting cytotoxicity and genotoxicity of nanomaterials became essential for nanotechnology development. The cell type and the intrinsic characteristics of titanium dioxide NPs can influence nanotoxicity. In this work, the cyto- and genotoxicity effects of standard reference material titanium dioxide NPs in primary bovine fibroblasts and immortalized Chinese hamster ovary epithelial (CHO) cells were determined and compared for the first time. Titanium dioxide NPs exposure revealed no cytotoxicity for primary bovine fibroblasts, while only higher concentrations tested (10 μg/ml) induce genotoxic effects in this cell model. In contrast, the lower concentrations of the titanium dioxide NPs cause the cyto- and genotoxic effects in CHO cells. Therefore, our finding indicates that the CHO line was more sensitive toward the effects of titanium dioxide NPs than the primary bovine fibroblast, which should be valuable for their environmental risk assessment.

Utility of Galleria mellonella larvae for evaluating nanoparticle toxicology

The use of nanoparticles in consumer products is currently on the rise, so it is important to have reliable methods to predict any associated toxicity effects. Traditional in vitro assays fail to mimic true physiological responses of living organisms against nanoparticles whereas murine in vivo models are costly and ethically controversial. For these reasons, this study aimed to evaluate the efficacy of Galleria mellonella as an alternative, non-rodent in vivo model for examining nanoparticle toxicity. Silver, selenium, and functionalized gold nanoparticles were synthesized, and their toxicity was assessed in G. mellonella larvae. The degree of acute toxicity effects caused by each type of NP was efficiently detected by an array of indicators within the larvae: LD₅₀ calculation, hemocyte proliferation, NP distribution, behavioral changes, and histological alterations. G. mellonella larvae are proposed as a nanotoxicological model that can be used as a bridge between in vitro and in vivo murine assays in order to obtain better predictions of NP toxicity.

Silver Sulfide Nanoparticles Reduce Nitrous Oxide Emissions by Inhibiting Denitrification in the Earthworm Gut

The accumulation of Ag₂S in agricultural soil via application of Ag-containing sludge potentially affects the functioning of soil microorganisms and earthworms (EWs) due to the strong antimicrobial properties of Ag. This study examined the effects of Ag₂S nanoparticles (Ag₂S-NPs) on the EW-mediated (Eisenia fetida and Pontoscolex corethrurus) soil N cycle. We used 16S rRNA gene-based sequencing and quantitative polymerase chain reaction to examine the bacterial community and nitrification/denitrification-related gene abundance. The presence of either EWs or Ag significantly increased denitrification and N₂O emissions. However, the addition of Ag₂S to EW-inhabited soil reduced N₂O emissions by 14-33%. Furthermore, Ag₂S caused a low-dose stimulation but a high-dose inhibition to N₂O flux from the EW gut itself. Accordingly, an increase in Ag in the EW gut caused a decrease in the relative abundance of denitrifiers in both the soil and the gut, especially for the dominant genus Bacillus. Ag₂S also decreased the copy numbers of nitrification gene (nxrB) and denitrification genes (napA, nirS, and nosZ) in EW gut, leading to the observed decrease in N₂O emissions. Collectively, applying Ag₂S-containing sludge disturbs the denitrification function of the EW gut microbiota and the cycling of N in soil-based systems.

Malignancy and tumorigenicity of melanoma B16 cells are not affected by silver and gold nanoparticles

Gold (AuNP) and silver (AgNP) nanoparticles have been incorporated into many therapeutic and diagnostic applications. However, previous studies revealed toxic properties as well as the hormesis phenomenon of many nanoparticles in different biological models. To evaluate the effects of low concentrations of AuNP and AgNP on murine melanoma cells B16F1 and B16F10 and relate them with phenotype changes, cells were exposed for 24 and 48 h. No cytotoxicity was observed for B16 cells through neutral red, MTT, trypan blue, and crystal violet assays at concentrations from 0.01 to 10 ng mL^-1. Likewise, the nanoparticles did not interfere with drug-efflux activity, cell migration, cell cycle, and colony formation. Slight toxicity was observed for B16F10 exposed to 100 ng mL^-1, with a decreased number of viable and attached cells, indicating differential sensitivity of B16F1 and B16F10 cells to the nanoparticles. Furthermore, colony size dispersion decreased for both B16 cell sub-lines. Therefore, there is no evidence that the tested concentrations of AuNP and AgNP can render B16 cells more aggressive and malignant, which is important since both nanoparticles are already largely used in nanotechnological products. Considering studies that have showed the hormesis effect of nanoparticles at low concentrations, which could protect cancer cells against chemotherapy, further investigation is advised.

Apoferritin and Apoferritin-Capped Metal Nanoparticles Inhibit Arginine Kinase of Trypanosoma brucei

The aim of this study was to explore the inhibitory potential of apoferritin or apoferritin-capped metal nanoparticles (silver, gold and platinum) against Trypanosomabrucei arginine kinase. The arginine kinase activity was determined in the presence and absence of apoferritin or apoferritin-capped metal nanoparticles. In addition, kinetic parameters and relative inhibition of enzyme activity were estimated. Apoferritin or apoferritin-capped metal nanoparticles’ interaction with arginine kinase of T. brucei led to a >70% reduction in the enzyme activity. Further analysis to determine kinetic parameters suggests a mixed inhibition by apoferritin or apoferritin-nanoparticles, with a decrease in V_max. Furthermore, the K_m of the enzyme increased for both ATP and L-arginine substrates. Meantime, the inhibition constant (K_i) values for the apoferritin and apoferritin-nanoparticle interaction were in the submicromolar concentration ranging between 0.062 to 0.168 nM and 0.001 to 0.057 nM, respectively, for both substrates (i.e., L-arginine and ATP). Further kinetic analyses are warranted to aid the development of these nanoparticles as selective therapeutics. Also, more studies are required to elucidate the binding properties of these nanoparticles to arginine kinase of T. brucei.

Converting natural nanoclay into modified nanoclay augments the toxic effect of natural nanoclay on aquatic invertebrates

There is much interest in converting natural nanoclay into modified forms for a variety of applications. Aquatic organisms have been exposed to natural nanoclay throughout their entire evolutionary history, but concerns have been raised about the effects of modified nanoclay on aquatic organisms. We investigated the potential toxicity of a natural nanoclay (Na+ montmorillonite) and two modified nanoclays (Cloisite® 30B and Novaclay^TM) on survivorship and body growth of Daphnia magna and Chironomus dilutus. Natural nanoclay had no harmful effect on C. dilutus but reduced the survival (~1mgL^-1) and body growth (~100 mgL^-1) of D. magna. Novaclay^TM had no harmful effects on C. dilutus or the body growth of D. magna but an intermediate concentration (1 mgL^-1) caused a stronger reduction in D. magna survival during chronic exposure than did natural nanoclay. Cloisite® 30B adversely affected D. magna survival at concentrations as low as 0.01 mgL^-1 and nearly all D. magna died when exposed to concentrations of Cloisite® 30B that exceeded 10 mgL^-1 during acute exposure and 1 mgL^-1 during chronic exposure. Though Cloisite® 30B appeared to have no effect on the body growth of surviving D. magna, Cloisite® 30B reduced C. dilutus body growth (100 mgL^-1). Cloisite® 30B likely has higher toxic effects due to the presence of quaternary ammonium compounds and/or particle stability. Our work demonstrates that natural nanoclay has harmful effects on aquatic animals and that the different ways of converting natural nanoclay into different types of modified nanoclays augments the toxic effect of nanoclay to differing degrees.

In light-sensitive drug delivery system nanoparticles mediate oxidative stress

In light-sensitive drug delivery systems, more and more nanoparticles were applied to load various drug molecules. However, few studies focused on their biomedical effects such as the regulation of heme oxygenase-1 (HO-1) expression and reactive oxygen species (ROS) generation which could influence cellular redox reaction. In the present article, through review of literature, analysis of high-throughput sequencing database, the mechanisms of drug delivery based on organic (poly-lactic-co-glycolic acid (PLGA) and polyethylene glycol (PEG)) and inorganic (Au, ZnO, SiO₂ and TiO₂) nanoparticles were introduced briefly. Besides, it was also expounded that nuclear factor-erythroid 2 (NF-E2)-related factor 2/BTB domain and CNC homolog 1 (Nrf2/Bach1) might be involved in the regulation of HO-1 and the quantum effect of photon altered ROS generation. The exogenous nanoparticles certainly have various biomedical effects that even affect the pathogenesis of some diseases like atopic dermatitis. Thus, biomedical effect of nanoparticles depends on HO-1/ROS needs further research.

Effects of silver nanoparticles on coupled nitrification-denitrification in suspended sediments

The effects of varying concentrations of Ag NPs on coupled nitrification and denitrification (CND) in two suspended sediments (SPSs) sizes were investigated using isotopic tracer method. In general, 0.5 and 5 mg/L Ag NPs had less effect on CND, while 2 and 10 mg/L Ag NPs exhibited the improvement and inhibition effect, respectively. The CND improvement by 2 mg/L NPs was mainly due to the enhanced nitrifying and denitrifying enzyme activity. However, 10 mg/L Ag NPs inhibited NH₄⁺ oxidation by directly reducing the AMO activity and AOB abundance. The inhibition on NAR and NIR activity and their encoding narG and nirK gene abundance further inhibited NO₃^- and NO₂^- reduction, leading to a dramatic decrease in the ¹⁵N-N₂ production. The above inhibition effects were attributed to the nano-effects of Ag NPs, which led to the excessive ROS amount and the decreased T-AOC level in microbial systems. But the connection between nitrification and denitrification was not broken after Ag NPs exposure. Moreover, the results indicated that N-cycling in clay and silt-type SPS systems could be more sensitive than sand-type SPS systems to NP exposure. The findings provide a basis for evaluating the environmental risks of Ag NPs in water-sediment systems.

Hormesis Effects of Nano- and Micro-sized Copper Oxide

The concerns about the possible risk of manufactured nanoparticles (NPs) have been raised recently. Nano- and micro-sized copper oxide (CO and CONP) are widely used in many industries. In this regard, in-vitro studies have demonstrated that CONP is a toxic compound in different cell lines. Despite their unique properties, NPs possess unexpected toxicity profiling relative to the bulk materials. This study was designed to examine and compare the toxic effects of CO and CONPs in-vivo and in isolated rat mitochondria. Male Wistar albino rats received 50 to 1000 mg/kg CO or CONP by gavage and several toxicological endpoints including biochemical indices and oxidative stress markers. Then, the pathological parameters in the multiple organs such as liver, brain, spleen, kidney, and intestine were assessed. Mitochondria were isolated from the rat liver and several mitochondrial indices were measured. The results of this study demonstrated that CO and CONP exhibited biphasic dose-response effects. CONPs showed higher toxicity compared with the bulk material. There were no significant changes in the results of CONP and CO in isolated rat liver mitochondria. The present studies provided more information regarding the hormetic effects of CO and CONPs in-vivo and in isolated rat mitochondria.

Microcellular Environmental Regulation of Silver Nanoparticles in Cancer Therapy: A Critical Review

Silver nanoparticles (AgNPs) play significant roles in various cancer cells such as functional heterogeneity, microenvironmental differences, and reversible changes in cell properties (e.g., chemotherapy). There is a lack of targets for processes involved in tumor cellular heterogeneity, such as metabolic clampdown, cytotoxicity, and genotoxicity, which hinders microenvironmental biology. Proteogenomics and chemical metabolomics are important tools that can be used to study proteins/genes and metabolites in cells, respectively. Chemical metabolomics have many advantages over genomics, transcriptomics, and proteomics in anticancer therapy. However, recent studies with AgNPs have revealed considerable genomic and proteomic changes, particularly in genes involved in tumor suppression, apoptosis, and oxidative stress. Metabolites interact biochemically with energy storage, neurotransmitters, and antioxidant defense systems. Mechanobiological studies of AgNPs in cancer metabolomics suggest that AgNPs may be promising tools that can be exploited to develop more robust and effective adaptive anticancer therapies. Herein, we present a proof-of-concept review for AgNPs-based proteogenomics and chemical metabolomics from various tumor cells with the help of several technologies, suggesting their promising use as drug carriers for cancer therapy.

Silver nanoparticles and Fe(III) co-regulate microbial community and N2O emission in river sediments

The effects of environmental concentration silver nanoparticles (ecAgNPs) on microbial communities and the nitrogen cycling in river sediments remain largely uncharacterized. As a fundamental component of sediments, Fe(III) can interact with AgNPs and participate in nitrogen transformation processes. N₂O is an important intermediate in nitrogen transformation processes and can be a potent greenhouse gas with significant environmental effects. However, the impacts of the co-existence of AgNPs and Fe(III) on microbial communities and N₂O emission in river sediments are still unclear. In the present study, mesocosm experiments were conducted to assess the changes of microbial communities and N₂O emission in response to the co-existence of AgNPs and environmental concentration Fe(III). Our results revealed that the microbial community diversity and N₂O emission in river sediments responded differently to ecAgNPs (0.05 mg/kg) and high-polluting concentration AgNPs (hcAgNPs, 5 mg/kg), which was further regulated by the environmental concentration Fe(III) (1 mg/g and 10 mg/g). After ecAgNPs treatments, a marked increase was observed in microbial diversity compared to hcAgNPs treatments, regardless of the Fe(III) concentration in the sediment. The β-NTI index indicated that AgNPs had stronger impacts on phylogenetic distance of bacterial communities in sediments containing 1 mg/g Fe(III) than that containing 10 mg/g Fe(III). In sediments containing 1 mg/g Fe(III), ecAgNPs did not affect N₂O emission, but hcAgNPs significantly inhibited the emission of N₂O. However, in sediments containing 10 mg/g Fe(III), N₂O emission was significantly stimulated upon exposure to ecAgNPs, but the inhibition effect of hcAgNPs was barely observed. Functional prediction and real-time PCR analyses indicated that AgNPs and Fe(III) predominantly affected N₂O emissions by affecting the abundance of the nirK gene. Our results provide new insights into the ecological impacts of the co-existence of environmental concentration AgNPs and Fe(III) in altering microbial communities and nitrogen transformation functions in river sediments.

Silver Nanoparticles against Foodborne Bacteria. Effects at Intestinal Level and Health Limitations

Foodborne diseases are one of the factors that endanger the health of consumers, especially in people at risk of exclusion and in developing countries. The continuing search for effective antimicrobials to be used in the food industry has resulted in the emergence of nanotechnology in this area. Silver nanoparticles (Ag-NPs) are the nanomaterial with the best antimicrobial activity and therefore, with great potential of application in food processing and packing. However, possible health effects must be properly addressed to ensure food safety. This review presents a detailed description on the main applications of Ag-NPs as antimicrobial agents for food control, as well as the current legislation concerning these materials. Current knowledge about the impact of the dietary exposure to Ag-NPs in human health with special emphasis on the changes that nanoparticles undergo after passing through the gastrointestinal tract and how they alter the oral and gut microbiota, is also summarized. It is concluded that given their potential and wide properties against foodborne pathogens, research in Ag-NPs is of great interest but is not exempt from difficulties that must be resolved in order to certify the safety of their use.

Reactive oxygen species (ROS)-responsive ferrocene-polymer-based nanoparticles for controlled release of drugs

Ferrocene-containing nanoparticles show reversible redox activity that could trigger drug release mediated by reactive oxygen species (ROS).

Physiological and antioxidative responses to GO/PANI nanocomposite in intact and demucilaged seeds and young seedlings of Salvia mirzayanii

The current study aimed to investigate the impacts of different concentrations of GO/PANI nanocomposites (25, 50 and 100 mg L^-1), in comparison with GO and PANI, on seed germination behaviors, morpho-physiological and biochemical traits in intact (mucilaginous) and demucilaged seeds, and young seedlings of the medicinal plant Salvia mirzayanii. Upon exposure to GO, seed germination was delayed and reduced, and growth attributes (root and shoot length, shoot fresh weight, and total chlorophyll content) declined, all of which could be attributed to the reductions in water uptake and oxidative stress particularly in demucilaged seeds. A hormetic dose-dependent response was observed for the growth traits in both intact and demucilaged seedlings upon exposure to GO/PANI concentrations, i.e. low-concentration stimulation and high-concentration repression. Elevated levels of H₂O₂ in shoot tissue of the seedlings exposed to GO and high concentration of GO/PANI, in comparison with those exposed to low levels of GO/PANI and control, were linked with the activities of the antioxidant enzymes SOD, CAT, POD, and total phenolics. Overall, the results showed high toxicity of GO on germination and early growth of S. mirzayani that was more evident in demucilaged seedlings, whereas GO/PANI stimulated germination, and the effects on seedling growth were stimulatory or inhibitory depending on the application dose and presence of mucilage. Furthermore, the capacity of GO/PANI nanocomposites to improve germination and cause a regular porosity pattern in roots accompanied by improved water uptake and early establishment of S. mirzayanii propose potential implications of GO/PANI nanocomposites for seeds/plants in drought-prone ecosystems.

Surface modification of silver nanoparticle (AgNP) by liposomal encapsulation mitigates AgNP-induced inflammation

Silver nanoparticles (AgNP) are widely used in a variety of consumable products as antibacterial to prevent or treat infection. Unfortunately, evidence exits that AgNP induces inflammation which can worsen with repeated human exposure. However, there is little or no research on how to mitigate these adverse effects due to AgNP induced-toxicity. Here, we investigated if surface modification of AgNP by liposomal encapsulation suppresses AgNP-mediated inflammatory responses in THP1 monocytes and THP1 differentiated macrophages (TDM). AgNP was encapsulated in a dipalmitoyl phosphatidyl choline- (DPPC)/cholesterol-based liposome by extrusion through a 100-nm polycarbonate membrane to form Lipo-AgNP. It was found as expected that AgNP induced significant release of IL-1β, IL-6, IL-8 and TNF-α in THP1 monocytes more than the basal level. Interestingly, release of these cytokines was suppressed by Lipo-AgNP. In TDMs, AgNP and Lipo-AgNP induced IL-8 release (p < .0001), but Lipo-AgNP maintained IL-8 release at levels significantly lower than that of AgNP (p < .01). However, both AgNP and Lipo-AgNP suppressed IL-1β and TNF-α release in LPS-stimulated THP1 monocytes and LPS-stimulated or unstimulated TDM respectively. We finally showed that Lipo-AgNP inhibits STAT-3 and this may be responsible for regulating the uncontrolled inflammation induced by AgNP likely mediated STAT-3 protein expression in LPS stimulated THP1 monocytes and TDMs, both LPS-stimulated and unstimulated. This data showed that Lipo-AgNP suppressed AgNP induced inflammation, making Lipo-AgNP particularly useful in treatment of bacteria induced inflammatory diseases and inflammatory cancers.

Antiprotozoal activity of silver nanoparticles against Cryptosporidium parvum oocysts: New insights on their feasibility as a water disinfectant

Cryptosporidium is a protozoan of extremely medical and veterinary impact; whose oocysts donate a considerable resistant to the water treatment processes. Therefore, this study aimed to explore the impacts of silver nanoparticles (AgNPs) on count and viability of the Cryptosporidium parvum (CP) isolated from different tap water samples. The oocysts were exposed to AgNPs at different dosages of 0.05, 0.1 and 1 ppm for several contact times (30 min to 4 h). The results showed a significant decrease in oocyst count and viability in a dose-dependent manner. Additionally, AgNPs at a conc. of 1 ppm for 30 min and 0.1 ppm for 1 h reduced the oocysts by 97.2 and 94.4%, respectively. Comparatively, there was a noticeable increase in the oocyst's viability at 2 and 4 h, which emphasized that the time of contact between AgNPs and CP was not a major influencing factor for successful application of AgNPs in the nano-water treatment.

Molecular and Morphological Evidence of Hepatotoxicity after Silver Nanoparticle Exposure: A Systematic Review, In Silico, and Ultrastructure Investigation

Silver nanoparticles (AgNPs) have been widely used in a variety of applications in innovative development; consequently, people are more exposed to this particle. Growing concern about toxicity from AgNP exposure has attracted greater attention, while questions about nanosilver-responsive genes and consequences for human health remain unanswered. By considering early detection and prevention of nanotoxicology at the genetic level, this study aimed to identify 1) changes in gene expression levels that could be potential indicators for AgNP toxicity and 2) morphological phenotypes correlating to toxicity of HepG2 cells. To detect possible nanosilver-responsive genes in xenogenic targeted organs, a comprehensive systematic literature review of changes in gene expression in HepG2 cells after AgNP exposure and in silico method, connection up- and down-regulation expression analysis of microarrays (CU-DREAM), were performed. In addition, cells were extracted and processed for transmission electron microscopy to examine ultrastructural alterations. From the Gene Expression Omnibus (GEO) Series database, we selected genes that were up- and down-regulated in AgNPs, but not up- and down-regulated in silver ion exposed cells, as nanosilver-responsive genes. HepG2 cells in the AgNP-treated group showed distinct ultrastructural alterations. Our results suggested potential representative gene data after AgNPs exposure provide insight into assessment and prediction of toxicity from nanosilver exposure.

Oxidative Stress Effects of Soluble Sulfide on Human Hepatocyte Cell Line LO2

Soluble sulfide is well known for its toxicity and corrosion for hundreds of years. However, recent studies have demonstrated that hydrogen sulfide (H₂S)-a novel gasotransmitter-supports a critical role during neuromodulation, cell proliferation, and cardioprotection for organisms. In particular, soluble sulfide plays multifaceted signaling functions in mammals during oxidative stress processes. However, the specific molecular regulation of soluble sulfide during oxidative stress remains unclear. In this study, Na₂S was implemented as a soluble sulfide donor to expose LO2 cells. The 3-(4,5-dimethylthiazolyl-2),-2,5-diphenyltetrazolium bromide (MTT) assay, hydroxyl radical assay, superoxide dismutase (SOD) assay, and glutathione peroxidase (GSH-PX) assay were applied to analyze cytotoxicity, hydroxyl radical levels, SOD and GSH-Px activities, respectively. Soluble sulfide at a concentration 0.01-1.0 mM/L resulted in a marked and concentration-dependent reduction of LO2 cell viability. At low concentrations, sulfide solutions increased SOD activity and GSH-Px activity of LO2 after 24 h exposure, exhibiting a clear hormesis-effect and indicating the protective ability of soluble sulfide against oxidative stress. The decline in SOD and GSH-Px and the increase in hydroxyl radical (0.08-1.0 mM/L) suggested that oxidative damage could be a possible mechanism for sulfide-induced cytotoxicity.

Metabolites change of Scenedesmus obliquus exerted by AgNPs

With increasing emission of silver nanoparticles (AgNPs) into the environment, it is important to understand the effects of ambient concentration of AgNPs. The biological effects of AgNPs on Scenedesmus obliquus, a ubiquitous freshwater microalgae, was evaluated. AgNPs exerted a minor inhibitory effect at low doses. Non-targeted metabolomic studies were conducted to understand and analyze the effect of AgNPs on algal cells from a molecular perspective. During the 48 hr of exposure to AgNPs, 30 metabolites were identified, of which nine had significant changes compared to the control group. These include d-galactose, sucrose, and d-fructose. These carbohydrates are involved in the synthesis and repair of cell walls. Glycine, an important constituent amino acid of glutathione, increased with AgNP exposure concentration increasing, likely to counteract an increased intracellular oxidative stress. These results provide a new understanding of the toxicity effects and mechanism of AgNPs. These metabolites could be useful biomarkers for future research, employed in the early detection of environmental risk from AgNPs.

Metabolite changes behind faster growth and less reproduction of Daphnia similis exposed to low-dose silver nanoparticles

With increasing presence of silver nanoparticles (AgNPs) into the environment, the chronic and low-dose effects of AgNPs are of vital concern. This study evaluated chronic physiological effects of AgNPs on Daphnia similis, which were exposed to two ambient encountered concentrations (0.02 and 1 ppb) of AgNPs for 21 days. It was observed that the low-dose AgNPs stimulated a significant increase in average length/dry mass, but inhibited reproduction compared to control specimens. Non-targeted metabolomics based on liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-QTOFMS-MS) and gas chromatograph-quadrupole time of flight mass spectrometry (GC-QTOF-MS) were utilized to elucidate the underlying molecular mechanisms of these responses. Forty one metabolites were identified, including 18 significantly-changed metabolites, suggesting up regulation in protein digestion and absorption (amino acids, such as isoleucine, tryptophan, lysine, leucine, valine, aspartic acid, threonine, tyrosine) and down regulation of lipid related metabolism (fatty acids, such as arachidonic acid, stearidonic acid, linoelaidic acid and eicosapentaenoic acid) were key events in these responses. The increase in these amino acid contents explains the accelerated growth of D. similis from the metabolic pathway of aminoacyl-tRNA biosynthesis. Down regulation of fatty acid contents corresponds to the observed drop in the reproduction rate considering the fatty acid biological enzymatic reaction pathways. Significant changes in metabolites provided a renewed mechanistic understanding of low concentration chronic toxicity of AgNP toxicity on D. similis.

A Current Overview of the Biological and Cellular Effects of Nanosilver

Nanosilver plays an important role in nanoscience and nanotechnology, and is becoming increasingly used for applications in nanomedicine. Nanosilver ranges from 1 to 100 nanometers in diameter. Smaller particles more readily enter cells and interact with the cellular components. The exposure dose, particle size, coating, and aggregation state of the nanosilver, as well as the cell type or organism on which it is tested, are all large determining factors on the effect and potential toxicity of nanosilver. A high exposure dose to nanosilver alters the cellular stress responses and initiates cascades of signalling that can eventually trigger organelle autophagy and apoptosis. This review summarizes the current knowledge of the effects of nanosilver on cellular metabolic function and response to stress. Both the causative effects of nanosilver on oxidative stress, endoplasmic reticulum stress, and hypoxic stress—as well as the effects of nanosilver on the responses to such stresses—are outlined. The interactions and effects of nanosilver on cellular uptake, oxidative stress (reactive oxygen species), inflammation, hypoxic response, mitochondrial function, endoplasmic reticulum (ER) function and the unfolded protein response, autophagy and apoptosis, angiogenesis, epigenetics, genotoxicity, and cancer development and tumorigenesis—as well as other pathway alterations—are examined in this review.

Silver nanoparticle-induced hormesis of astroglioma cells: A Mu-2-related death-inducing protein-orchestrated modus operandi

Hormesis is a dose-response phenomenon that, when applied to nanomaterial-biological interactions, refers to growth stimulation at low doses and growth inhibition at high doses. MUDENG (Mu-2-related death-inducing gene, MuD) is involved in cell death signaling. Astrocytes, the major glial cell type in the central nervous system, are a major source of brain tumors. In this study, we investigated whether silver nanoparticles (AgNPs) induce hormesis in astroglioma cells and the possible involvement of MuD in AgNP-induced hormesis. AgNPs exhibited cytotoxic effects on cell proliferation in a dose-dependent manner and increased MuD expression was observed during AgNP-induced astroglioma hormesis. Studies using MuD-knockout cells and MuD siRNA transfection showed that MuD might influence cell viability upon AgNP treatment. In addition, apoptotic cell population and production of reactive oxygen species in the absence of MuD were significantly increased. The phosphorylation of two mitogen-activated protein kinases, p38 and extracellular signal-regulated kinase (ERK), but not c-Jun N-terminal kinases (JNK), was observed upon AgNP stimulation. In summary, AgNPs at low doses induced hormesis of human astroglioma cells, and MuD and p38/ERK mediators are involved in AgNP-induced astroglioma hormesis, resulting in beneficial effects from the cellular point of view.

Silver nanoparticles improve structural stability and biocompatibility of decellularized porcine liver

No ideal cross-linking agent has been identified for decellularized livers (DLs) yet. In this study, we evaluated structural improvements and biocompatibility of porcine DLs after cross-linking with silver nanoparticles (AgNPs). Porcine liver slices were decellularized and then loaded with AgNPs (100 nm) after optimization of the highest non-toxic concentration (5 µg/mL) using Human hepatocellular carcinoma (HepG2) and EAhy926 human endothelial cell lines. The cross-linking effect of AgNPs was evaluated and compared to that of glutaraldehyde and ethyl carbodiimide hydrochloride and N-hydroxysuccinimide. The results indicated that AgNPs improved the ultra-structure of DLs' collagen fibres with good porosity and increased DLs' resistance against in vitro degradation with good cytocompatibility. AgNPs decreased the host inflammatory reaction against implanted porcine DL slices in vivo and increased the polarization of M2 macrophages. Thus, structural and functional improvements of Porcine DLs could be achieved using AgNPs.

Nanoparticle Exposure and Hormetic Dose-Responses: An Update

The concept of hormesis, as an adaptive response of biological systems to moderate environmental challenges, has raised considerable nano-toxicological interests in view of the rapid pace of production and application of even more innovative nanomaterials and the expected increasing likelihood of environmental and human exposure to low-dose concentrations. Therefore, the aim of this review is to provide an update of the current knowledge concerning the biphasic dose-responses induced by nanoparticle exposure. The evidence presented confirmed and extended our previous findings, showing that hormesis is a generalized adaptive response which may be further generalized to nanoscale xenobiotic challenges. Nanoparticle physico-chemical properties emerged as possible features affecting biphasic relationships, although the molecular mechanisms underlining such influences remain to be fully understood, especially in experimental settings resembling long-term and low-dose realistic environmental exposure scenarios. Further investigation is necessary to achieve helpful information for a suitable assessment of nanomaterial risks at the low-dose range for both the ecosystem function and the human health.

A systematic review on silver nanoparticles-induced cytotoxicity: Physicochemical properties and perspectives

With the development of nanotechnology, silver nanoparticles (Ag-NPs) have become one of the most in-demand nanoparticles owing to their exponential number of uses in various sectors. The increased use of Ag-NPs-enhanced products may result in an increased level of toxicity affecting both the environment and living organisms. Several studies have used different model cell lines to exhibit the cytotoxicity of Ag-NPs, and their underlying molecular mechanisms. This review aimed to elucidate different properties of Ag-NPs that are responsible for the induction of cellular toxicity along with the critical mechanism of action and subsequent defense mechanisms observed in vitro. Our results show that the properties of Ag-NPs largely vary based on the diversified synthesis processes. The physiochemical properties of Ag-NPs (e.g., size, shape, concentration, agglomeration, or aggregation interaction with a biological system) can cause impairment of mitochondrial function prior to their penetration and accumulation in the mitochondrial membrane. Thus, Ag-NPs exhibit properties that play a central role in their use as biocides along with their applicability in environmental cleaning. We herein report a current review of the synthesis, applicability, and toxicity of Ag-NPs in relation to their detailed characteristics.

Silver Nanoparticles Alter Cell Adhesion and Proliferation of Sheep Primary Mesothelial Cells

BACKGROUND

Human exposure to engineered nanoparticles has been linked to pleural effusion, inflammation and fibrosis. Silver nanoparticles (AgNPs) are widely used in medical and domestic products, increasing the risk of occupational and domestic exposure. We assessed the influence of AgNPs on adhesion and proliferation of sheep primary pleural mesothelial cells.

MATERIALS AND METHODS

Cells were used for cell adhesion (90 min) and proliferation experiments (3 days) while exposed to 20 nm and 60 nm AgNPs (0.2 μg/ml and 2 μg/ml) using colorimetric assays.

RESULTS

Exposure to 0.2 μg/ml of 20 nm and 60 nm AgNPs significantly increased cell adhesion, while at 2 μg/ml this effect was not elicited. Cell proliferation was significantly increased by both 20 nm and 60 nm AgNPs at 0.2 μg/ml, while at 2 μg/ml this effect was only elicited by the 60 nm AgNPs.

CONCLUSION

AgNPs alter the adhesive and proliferative properties of primary pleural mesothelial cells.

Automatic detection of particle size distribution by image analysis based on local adaptive canny edge detection and modified circular Hough transform

To obtain size distribution of nanoparticles, scanning electron microscope (SEM) and transmission electron microscopy (TEM) have been widely adopted, but manual measurement of statistical size distributions from the SEM or TEM images is time-consuming and labor-intensive. Therefore, automatic detection methods are desirable. This paper proposes an automatic image processing algorithm which is mainly based on local adaptive Canny edge detection and modified circular Hough transform. The proposed algorithm can utilize the local thresholds to detect particles from the images with different degrees of complexity. Compared with the results produced by applying global thresholds, our algorithm performs much better. The robustness and reliability of this method have been verified by comparing its results with manual measurement, and an excellent agreement has been found. The proposed method can accurately recognize the particles with high efficiency.

Toxicity of nanomaterials found in human environment

The US National Nanotechnology Initiative (NNI) defines nanotechnology as “the understanding and control of matter at dimensions between approximately 1 and 100 nm, where unique phenomena enable novel applications.” Recent scientific reports available in the literature clearly demonstrate the potential benefits of nanotechnology in consumer and industrial products. More and more nanomaterials are expected to be used in consumer products. This is expected to lead to increased human exposure to nanomaterials in their daily lives. Therefore, the effect of nanomaterials present in human environment is an area of increasing scientific interest. The information presented in this review is obtained from the current literature. It indicates that nanomaterials found in human environment may have potential for toxicological effects. However, the current literature on toxicological effects of nanomaterials is diverse. The current data are presented from studies without harmonization. These studies have used different in vitro and in vivo test models, different sources of test nanomaterials, different methods for nanomaterial characterization, and different experimental conditions. Therefore, these data are hard to interpret. More research on nanomaterial characterization, biological interaction, toxicity, and health effects is needed. The test methods need to be validated. Positive and negative controls for nanotoxicity need to be identified. Toxicity data harmonization needs to be done. Therefore, general information is not currently available for risk evaluation of certain nanomaterials that might be present in consumer products or that may enter into the market in future. Standardized and validated methods are necessary for toxicity assessment of nanomaterials. Therefore, in the absence of standardized validated methods any specific regulatory testing requirements for nanomaterials are currently premature. We conclude that the benefits of nanomaterials found currently in human environment are many, but their overall adverse effects on human health are limited.

Responses of human hepatoma HepG2 cells to silver nanoparticles and polycyclic aromatic hydrocarbons

The nanotechnology has revolutionized the global market with silver nanoparticles (AgNP) occupying a prominent position due to their remarkable anti-bacterial properties. However, there is no data about the adverse and toxic effects of associations of AgNP and ubiquitous compounds, such as polycyclic aromatic hydrocarbons (PAH). In the current study, we investigated the responses of HepG2 cells to realistic concentrations of AgNP (0.09, 0.9, and 9 ng ml^-1) and mixture of PAH (30 and 300 ng ml^-1), separately and in association. Cell viability and cytotoxicity (neutral red retention and MTT production assays) and proliferation (crystal violet [CV] assay), xenobiotic efflux transporter activity (rhodamine B accumulation assay), ROS levels (dichlorodihydrofluorescein diacetate assay), and lipid peroxidation (pyrenylphosphine-1-diphenyl assay) were analyzed. There was no decreases of cell viability after exposure to AgNP, PAH and most of AgNP + PAH associations, but increases of cell viability/number (CV assay) occurred. Efflux transporter activity was not affected, with exception of one AgNP + PAH associations, ROS levels increased, but lipid peroxidation decreased. Some toxicological interactions occurred, particularly for the highest concentrations of AgNP and PAH, but there is no evidence that these interactions increased the toxicity of AgNP and PAH.

Glucose capped silver nanoparticles induce cell cycle arrest in HeLa cells

This study aims to determine the interaction (uptake and biological effects on cell viability and cell cycle progression) of glucose capped silver nanoparticles (AgNPs-G) on human epithelioid cervix carcinoma (HeLa) cells, in relation to amount, 2×10³ or 2×10⁴ NPs/cell, and exposure time, up to 48h. The spherical and well dispersed AgNPs (30±5nm) were obtained by using glucose as reducing agent in a green synthesis method that ensures to stabilize AgNPs avoiding cytotoxic soluble silver ions Ag⁺ release. HeLa cells take up abundantly and rapidly AgNPs-G resulting toxic to cells in amount and incubation time dependent manner. HeLa cells were arrested at S and G2/M phases of the cell cycle and subG1 population increased when incubated with 2×10⁴ AgNPs-G/cell. Mitotic index decreased accordingly. The dissolution experiments demonstrated that the observed effects were due only to AgNPs-G since glucose capping prevents Ag⁺ release. The AgNPs-G influence on HeLa cells viability and cell cycle progression suggest that AgNPs-G, alone or in combination with chemotherapeutics, may be exploited for the development of novel antiproliferative treatment in cancer therapy. However, the possible influence of the cell cycle on cellular uptake of AgNPs-G and the mechanism of AgNPs entry in cells need further investigation.

Silver nanoparticles induce hormesis in A549 human epithelial cells

Despite the gaps in our knowledge on the toxicity of silver nanoparticles (AgNPs), the application of these materials is fast expanding, from medicine, to food as well as the use in consumer products. It has been reported that prolonged exposure might make cells more resistant to AgNPs. This prompted us to investigate if AgNPs may give rise to a hormetic response. Two types of AgNPs were used, i.e. colloidal AgNPs and an AgNP powder. For both types of nanosilver it was found that a low dose pretreatment of A549 human epithelial cells with AgNPs induced protection against a toxic dose of AgNPs and acrolein. This protection was more pronounced after pretreatment with the colloidal AgNPs. Interestingly, the mechanism of the hormetic response appeared to differ from that of acrolein. Adaptation to acrolein is related to Nrf2 translocation, increased mRNA expression of γGCS, HO-1 and increased GSH levels and the increased GSH levels can explain the hormetic effect. The adaptive response to AgNPs was not related to an increase in mRNA expression of γGCS and GSH levels. Yet, HO-1 mRNA expression and Nrf2 immunoreactivity were enhanced, indicating that these processes might be involved. So, AgNPs induce adaptation, but in contrast to acrolein GSH plays no role.

Induction of Cell Cycle Arrest and Apoptotic Response of Head and Neck Squamous Carcinoma Cells (Detroit 562) by Caffeic Acid and Caffeic Acid Phenethyl Ester Derivative

Natural polyphenols have been observed to possess antiproliferative properties. The effects, including apoptotic potential of bioactive phenolic compounds, caffeic acid (CA) and its derivative caffeic acid phenethyl ester (CAPE), on cell proliferation and apoptosis in human head and neck squamous carcinoma cells (HNSCC) line (Detroit 562) were investigated and compared. Cancer cells apoptosis rates and cell cycle arrests were analysed by flow cytometry. Exposure to CA and CAPE was found to result in a dose-dependent decrease in the viability of Detroit 562 cells at different levels. CA/CAPE treatment did significantly affect the viability of Detroit 562 cells (MTT results). CAPE-mediated loss of viability occurred at lower doses and was more pronounced, with the concentrations which inhibit the growth of cells by 50% estimated at 201.43 μM (CA) and 83.25 μM (CAPE). Dead Cell Assay with Annexin V labelling demonstrated that CA and CAPE treatment of Detroit 562 cells resulted in an induction of apoptosis at 50 μM and 100 μM doses. The rise of mainly late apoptosis was observed for 100 μM dose and CA/CAPE treatment did affect the distribution of cells in G0/G1 phase. A combination of different phenolic compounds, potentially with chemotherapeutics, could be considered as an anticancer drug.

Governing factors affecting the impacts of silver nanoparticles on wastewater treatment

Silver nanoparticles (nanosilver or AgNPs) enter municipal wastewater from various sources, raising concerns about their potential adverse effects on wastewater treatment processes. We argue that the biological effects of silver nanoparticles at environmentally realistic concentrations (μgL^-1 or lower) on the performance of a full-scale municipal water resource recovery facility (WRRF) are minimal. Reactor configuration is a critical factor that reduces or even mutes the toxicity of silver nanoparticles towards wastewater microbes in a full-scale WRRF. Municipal sewage collection networks transform silver nanoparticles into silver(I)-complexes/precipitates with low ecotoxicity, and preliminary/primary treatment processes in front of biological treatment utilities partially remove silver nanoparticles to sludge. Microbial functional redundancy and microbial adaptability to silver nanoparticles also greatly alleviate the adverse effects of silver nanoparticles on the performance of a full-scale WRRF. Silver nanoparticles in a lab-scale bioreactor without a sewage collection system and/or a preliminary/primary treatment process, in contrast to being in a full scale system, may deteriorate the reactor performance at relatively high concentrations (e.g., mgL^-1 levels or higher). However, in many cases, silver nanoparticles have minimal impacts on lab-scale bioreactors, such as sequencing batch bioreactors (SBRs), especially when at relatively low concentrations (e.g., less than 1mgL^-1). The susceptibility of wastewater microbes to silver nanoparticles is species-specific. In general, silver nanoparticles have higher toxicity towards nitrifying bacteria than heterotrophic bacteria.

Sulfonated graphene-induced hormesis is mediated through oxidative stress in the roots of maize seedlings

The present study investigated the impact of sulfonated graphene (SG) on the growth of maize seedlings at a concentration range of 0-500mgL^-1. Stress-related parameters including reactive oxygen species (ROS), intracellular Ca²⁺, antioxidant enzyme activities, lipid peroxidation, membrane leakage, cell death and root morphology were examined to reveal the potential mechanisms. The results indicate that SG induced a hormesis effect on plant height, i.e., low-concentration (50mgL^-1) stimulation and high-concentration (500mgL^-1) inhibition. The hormesis effect of SG on plant height was directly correlated with ROS levels in roots. A low concentration (50mgL^-1) of SG promoted ROS scavenging, alleviated oxidative stress, enhanced the soluble protein (SP) content, and decreased intracellular Ca²⁺ and cell death in the roots. At a higher concentration (500mgL^-1), SG stimulated the generation of ROS in the roots, decreased SP content in the leaves, increased antioxidant enzyme activities, intracellular Ca²⁺, electrolyte leakage and cell death in the roots, and increased the malondialdehyde (MDA) content in both roots and leaves. Different changes were observed for root morphology at SG concentrations of 50 and 500mgL^-1, and a larger amount of SG was deposited onto the root surface at a concentration of 500mgL^-1 compared with 50mgL^-1.