Sub-chronic effects of AgNPs and AuNPs on Gammarus fossarum (Crustacea Amphipoda): From molecular to behavioural responses

Assessing toxicity mechanism of silver nanoparticles by using brine shrimp (Artemia salina) as model

The acute toxicity of silver nanoparticles (AgNPs) in Artemia salina is primarily attributed to the interaction between silver ions (Ag+) and chitin, which constitutes the main structural component of the organism's cuticle. To investigate this interaction and gain a deeper understanding of its nature, geometric optimization calculations and symmetry-adapted perturbation theory (SAPT0) analysis were performed. These calculations aimed to determine the most favorable conformation based on the binding energies of silver ions with chitin and to elucidate the underlying mechanisms of their interaction. The results indicate an ionic effect dependent on the ion state, with simulations revealing that Ag3+ ions have the potential to cause significant deformation of the chitin structure. Furthermore, this study evaluated the behavior of AgNPs using nauplii of A. salina instar I, assessing both mortality rates and cell damage. Toxicity of AgNPs was observed in A. salina at concentrations of 50 and 100 ppm within a timeframe of 24-48 h. The toxicity of AgNPs can be attributed to their interaction with the cuticle and subsequent modification of the chitin structure through the binding of ionic silver. Light microscopy (LM) analysis confirmed the presence of AgNPs in the cuticle, while confocal laser scanning microscopy (CLSM) revealed cellular damage. In addition, this research offers new perspectives on the toxicity mechanism of AgNPs by introducing a novel model that explores the interaction of silver ions with the cuticle of A. salina. These insights are derived from a combination of atomistic models and ecotoxicology assays.

Amelioration of neurobehavioral, biochemical, and morphological alterations associated with silver nanoparticles exposure by taurine in rats

The adverse effect of silver nanoparticles (AgNPs) on the nervous system is an emerging concern of public interest globally. Taurine, an essential amino acid required for neurogenesis in the nervous system, is well-documented to possess antioxidant, anti-inflammatory, and antiapoptotic activities. Yet, there is no report in the literature on the effect of taurine on neurotoxicity related to AgNPs exposure. Here, we investigated the neurobehavioral and biochemical responses associated with coexposure to AgNPs (200 µg/kg body weight) and taurine (50 and 100 mg/kg body weight) in rats. Locomotor incompetence, motor deficits, and anxiogenic-like behavior induced by AgNPs were significantly alleviated by both doses of taurine. Taurine administration enhanced exploratory behavior typified by increased track plot densities with diminished heat maps intensity in AgNPs-treated rats. Biochemical data indicated that the reduction in cerebral and cerebellar acetylcholinesterase activity, antioxidant enzyme activities, and glutathione level by AgNPs treatment were markedly upturned by both doses of taurine. The significant abatement in cerebral and cerebellar oxidative stress indices namely reactive oxygen and nitrogen species, hydrogen peroxide, and lipid peroxidation was evident in rats cotreated with AgNPs and taurine. Further, taurine administration abated nitric oxide and tumor necrosis factor-alpha levels cum myeloperoxidase and caspase-3 activities in AgNPs-treated rats. Amelioration of AgNPs-induced neurotoxicity by taurine was confirmed by histochemical staining and histomorphometry. In conclusion, taurine via attenuation of oxido-inflammatory stress and caspase-3 activation protected against neurotoxicity induced by AgNPs in rats.

Adverse effects of silver nanoparticles on aquatic plants and zooplankton: A review

With the rapid development of nanotechnology in the past decades, AgNPs are widely used in various fields and have become one of the most widely used nanomaterials, which leads to the inevitable release of AgNPs to the aquatic environment through various pathways. It is important to understand the effects of AgNPs on aquatic plants and zooplankton, which are widely distributed and diverse, and are important components of the aquatic biota. This paper reviews the effects of AgNPs on aquatic plants and zooplankton at the individual, cellular and molecular levels. In addition, the internal and external factors affecting the toxicity of AgNPs to aquatic plants and zooplankton are discussed. In general, AgNPs can inhibit growth and development, cause tissue damage, induce oxidative stress, and produce genotoxicity and reproductive toxicity. Moreover, the toxicity of AgNPs is influenced by the size, concentration, and surface coating of AgNPs, environmental factors including pH, salinity, temperature, light and co-contaminants such as NaOCl, glyphosate, As(V), Cu and Cd, sensitivity of test organisms, experimental conditions and so on. In order to investigate the toxicity of AgNPs in the natural environment, it is recommended to conduct toxicity evaluation studies of AgNPs under the coexistence of multiple environmental factors and pollutants, especially at natural environmental concentrations.

Assessing the effects of silver nanoparticles on the ecophysiology of Gammarus roeseli

Being part of the macrobenthic fauna, gammarids are efficient indicators of contamination of aquatic ecosystems by nanoparticles that are likely to sediment on the bottom. The present study investigates the effects of silver nanoparticles (nAg) on ecophysiological functions in Gammarus roeseli by using a realistic scenario of contamination. Indeed, an experiment was conducted during 72 h, assessing the effects of 5 silver nAg from 10 to 100 nm diluted at concentrations of maximum 5 µg L^-1 in a natural water retrieved from a stream and supplemented with food. The measured endpoints in gammarids were survival, silver concentrations in tissues, consumption of oxygen and ventilation of gills. Additionally, a set of biomarkers of the energetic metabolism was measured. After a 72-h exposure, results showed a concentration-dependent increase of silver levels in G. roeseli that was significant for the smallest nAg size (10 nm). Ecophysiological responses in G. roeseli were affected and the most striking effect was a concentration-dependent increase in oxygen consumption especially for the smallest nAg (10 to 40 nm), whereas ventilation of gills by gammarids was not changed. The potential mechanisms underlying these findings are discussed. Thus, we demonstrated the very low exposure concentration of 0.5 µg L^-1 for the small nAg size led to significant ecophysiological effects reinforcing the need to further investigate subtle effects on nanoparticles on aquatic organisms.

Gold nanoparticles enhance proliferation and osteogenic differentiation of periodontal ligament stem cells by PINK1-mediated mitophagy

OBJECTIVE

Evidence suggests that gold nanoparticles (AuNPs) improve osteogenic differentiation of periodontal ligament stem cells (PDLSCs), PTEN-induced putative kinase 1 (PINK1) dependent mitophagy modulates inter-clonal communication among PDLSCs with osteogenic heterogeneity, but the mechanism remains vague. Therefore, the current research assessed the influence of AuNPs on proliferation, osteogenic differentiation and mitophagy of PDLSCs and the potential mechanism was analyzed.

METHODS

Gold nanospheres with a diameter of 5, 10, 20, 40, and 80 nm were synthesized and characterized through transmission electron microscopy, and rat PDLSCs were isolated using flow sorting. Next, PDLSCs were treated with AuNPs or PINK1 lentivirus to obtain its overexpression or suppression. Proliferation and osteogenic differentiation were evaluated by CCK-8, ALP staining, ARS staining, and immunoblotting of OCN, OPN, RUNX2, ALP, BMP2, and COL1. Mitochondrial quality, homeostasis and quantity were assessed though JC-1 staining, immunoblotting of Tom20, Tim23 and HSP60 and mitochondrial ROS detection. PINK1, Parkin, Beclin1 and LC3 expression was quantified to investigate mitophagy, using RT-qPCR and immunoblotting and the formation of RFP-GFP-LC3-labeled autophagosomes were also measured.

RESULTS

The proliferation ability of PDLSCs almost reached the maximum under 20 nm AuNPs for 24 h. AuNPs enhanced the proliferation and osteogenic differentiation of PDLSCs, improved mitochondrial quality and homeostasis as well as attenuated mitochondrial quantity. Additionally, mitophagy was enhanced by PDLSCs. Activation of PINK1 synergistically enhanced AuNPs-mediated mitophagy, mitochondrial quality, homeostasis and osteogenic differentiation in PDLSCs, obtaining opposite effects when PINK1 was suppressed.

CONCLUSION

AuNPs enhance proliferation and osteogenic differentiation of PDLSCs through PINK1-mediated mitophagy.

Acute toxicity of nanoplastics on Daphnia and Gammarus neonates: Effects of surface charge, heteroaggregation, and water properties

Despite progress in evaluation of risk assessment, knowledge gaps largely exist understanding the toxicity of nanoplastics in aquatic systems considering nanoplastics surface properties, environmental media characteristics and species ecological traits. In this study, amidine - functionalized polystyrene nanoparticles (PS-NPLs) of 20, 40, 60 and 100 nm are considered using Geneva lake water and mineral water to investigate the behavior and effects in neonate organisms of the plankton Daphnia magna and the benthos Gammarus fossarum. Key parameters including ζ-potential, z-average diameter, conductivity, polydispersity index, pH, EC50 were investigated. The results showed that the toxicity of PS-NPLs exhibited a dose-response relationship, size- and exposure condition-dependent trend. The smaller size PS-NPLs (20 and 40 nm) induced higher adverse effects than PS-NPLs of 60 and 100 nm in both water conditions and crustacean species. Moreover, PS-NPLs were found more toxic in the mineral water compared to lake water. Principal component analysis evidenced that the surface charge and aggregation behavior are the most influential toxicity of PS-NPLs factor for D. magna and Gammarus fossarum, respectively. These results highlight the relationship between PS-NPLs intrinsic properties, their transformation behavior, water properties and species-specificity in the evaluation of PS-NPLs biological effects on crustacean neonates in natural aquatic environments.

Effects of environmentally relevant concentrations of microplastics on amphipods

Lack of microplastics (MP) toxicity studies involving environmentally relevant concentrations and exposure times is concerning. Here we analyzed the potential adverse effects of low density polyethylene (LDPE) MP at environmentally relevant concentration in sub-chronic exposure to two amphipods Gmelinoides fasciatus and Gammarus lacustris, species that naturally compete with each other for their habitats. 14-day exposure to 2 μg/L (8 particles/L corresponding to low exposure) and 2 mg/L (∼8400 particles/L, corresponding to high exposure) of 53-100 μm LDPE MP were used to assess ingestion and egestion of MP, evaluate its effects on amphipod mortality, swimming ability and oxidative stress level. Both amphipod species were effectively ingesting and egesting LDPE MP. On the average, 0.8 and 2.5 MP particles were identified in the intestines of each amphipod exposed to 2 μg/L and 2 mg/L LDPE MP, respectively. Therefore, intestinal MP after 14-day exposure did not fully reflect the differences in LDPE MP exposure concentrations. Increased mortality of both amphipods was observed at 2 mg/L LDPE MP and in case of G. lacustris also at 2 μg/L exposure. The effect of LDPE on swimming activity was observed only in case of G. fasciatus. Oxidative stress marker enzymes SOD, GPx and reduced glutathione GSH varied according to amphipod species and LDPE MP concentration. In general G. lacustris was more sensitive towards LDPE MP induced oxidative stress. Overall, the results suggested that in MP polluted environments, G. lacustris may lose its already naturally low competitiveness and become overcompeted by other more resistant species. The fact that in the sub-chronic foodborne exposure to environmentally relevant and higher LDPE MP concentrations all the observed toxicological endpoints were affected refers to the potential of MP to affect and disrupt aquatic communities in the longer perspective.

Emerging investigator series: metal nanoparticles in freshwater: transformation, bioavailability and effects on invertebrates

MNPs may undergo different environmental transformations in aquatic systems, consequently changing their mobility, bioavailability and toxicity to freshwater invertebrates.

Silver Nanoparticles and Ionic Silver Separation Using a Cation-Exchange Resin. Variables Affecting Their Separation and Improvements of AgNP Characterization by SP-ICPMS

Silver nanoparticles (AgNPs) are frequently found in everyday products and, as a consequence, their release into the environment cannot be avoided. Once in aquatic systems, AgNPs interact with natural constituents and undergo different transformation processes. Therefore, it is important to characterize and quantify AgNPs in environmental waters in order to understand their behavior, their transformation, and their associated toxicological risks. However, the coexistence of ionic silver (Ag⁺) with AgNPs in aquatic systems is one of the greatest challenges for the determination of nanosilver. Ion-exchange resins can be used to separate Ag⁺ from AgNPs, taking advantage of the different charges of the species. In this work, Dowex 50W-X8 was used to separate Ag⁺ and AgNPs in order to easily determine AgNP concentrations using inductively coupled plasma optical emission spectroscopy. The separation methodology was successfully applied to river water samples with different ratios of Ag⁺ and AgNPs. However, the methodology is not useful for wastewater samples. The described methodology also demonstrated an improvement in the determination of the particle size of AgNPs present in river waters by single particle inductively coupled plasma mass spectrometry when a significant amount of Ag⁺ is also present.