Nano-sized Plastic Research Articles

Exposure of Bromus hordeaceus to fossil- and plant-based micro- and nanoplastics: Impacts and plant-plastic interactions vary depending on polymer type and growth phase

Plastic pollution, especially pollution by micro- and nanoplastics, is now considered a potential threat to all ecosystems, including terrestrial ecosystems such as grassland habitats. This study investigated the impacts of micro- and nano-sized plastics on Bromus hordeaceus, a common grass species in European grasslands. The micro and nanoparticles were fossil-based polyethylene (PE) or plant-based polybutylene adipate terephthalate (PBAT), and these two plastics were used at two different concentrations. Here, we report data on plant development and plastic-plant interactions from two different experiments, (1) an in vitro experiment to test seed germination and establishment and (2) a soil experiment to test plant development and plastic-plant interactions specifically investigated as a form of perforation. Results from the in vitro experiment indicate that while seed germination success was unaffected by plastic type, the presence of all plastic particle types acted as a stimulant, increasing the total length of radicles and sprouts of germinated seeds. Conversely, results from the soil experiment showed that the growth of Bromus hordeaceus was negatively affected by the presence of microPBAT in the soil during the pot assay.Microscopic analysis confirmed that seed and plant structures interacted with all plastic particles via adsorption or perforation. This study demonstrates for the first time the ability of roots to penetrate plastics, especially microPBAT particles. Overall, our study concludes that both fossil-based and plant-based micro- and nano-plastics can influence plant growth, with effects varying based on plastic type, concentration, and plant growth phase. Further research is crucial to fully understand the intricate interactions between microplastics, soil properties, and plant development.

Distinctive toxic repercussions of polystyrene nano plastic towards aquatic non target species Nitrobacter vulgaris, Scenedesmus sp and Daphnia magna.

The widespread application of plastics and its eventual degradation to micro-sized or nano-sized plastics has led to several environmental concerns. Moreover, nanoplastics can easily cascade through the food chain accumulating in the aquatic organisms. Thus, our study focussed on investigating the hazardous impact of nano-sized plastics on aquatic species including Nitrobacter vulgaris, Scenedesmus sp, and Daphnia magna. Various concentrations of polystyrene nanoplastics ranging from 0.01 mg/L to 100 mg/L were tested against Nitrobacter vulgaris, Scenedesmus sp, and Daphnia magna. The minimum inhibitory concentration of polystyrene nanoplastics in Nitrobacter vulgaris was found to be 25 mg/L, and in Daphnia magna, the median lethal concentration 50 was observed to be 64.02 mg/L. Exposure of Scenedesmus sp with increasing nanoplastic concentrations showed a significant decrease in total protein (p < 0.001), and chlorophyll content (p < 0.01), whereas the lipid peroxidation increased (p < 0.001) significantly. Similarly, Nitrobacter vulgaris and Daphnia magna showed a significant decrease in catalase activity (p < 0.001) and an increase in lipid peroxidation levels (p < 0.01). Concomitant with lipid peroxidation results, decreased superoxide dismutase levels (p < 0.01) and protein concentrations (p < 0.01) were observed in Daphnia magna. Besides, the increasing concentration of polystyrene nanoplastics displayed an elevated mortality rate in Scenedesmus sp (p < 0.001) and Nitrobacter vulgaris (p < 0.01). Further, scanning electron microscopy analysis substantiated the morphological alterations in Nitrobacter vulgaris and Scenedesmus sp on exposure to polystyrene nanoplastics.

Preferential adsorption of medium molecular weight proteins in extracellular polymeric substance alleviates toxicity of small-sized microplastics to Skeletonema costatum

Extracellular polymeric substances (EPS) secreted by organisms tend to encapsulate microplastics (MPs), forming an EPS-corona that affects the fate of MPs in marine ecosystems. However, the impact of the EPS-corona on the biotoxicity of MPs to marine organisms remains poorly understood. Herein, the effect of the EPS-corona on the toxicity of polystyrene (PS) MPs of different sizes (0.1 and 1 µm) to Skeletonema costatum (S. costatum) was investigated. The preferential adsorption of medium molecule weight (∼55 kDa) proteins onto PS MPs mainly contributed to the EPS-corona formation, decreasing the surface charge negativity of small-sized PS MPs (0.1 µm) by 72.4 %. Nitrogen (N) and oxygen (O) moieties in polysaccharides and proteins were identified as the preferential adsorption sites in the EPS-PS MPs interaction. Density functional theory (DFT) calculations confirmed the nuclear magnetic resonance spectroscopy (NMR) results, revealing that the binding mode between EPS and PS MPs was mainly hydrogen bonding. In addition, EPS-corona increased the cell density of S. costatum by 35.5–36.0 % when exposed to small-sized PS MPs (0.1 µm, 25–50 mg/L). These findings provide new insights into how EPS-corona affects the environmental fate and ecological risks associated with micro- and nano-sized plastics in marine ecosystems.

Environmental nanoplastics quantification by pyrolysis-gas chromatography–mass spectrometry in the Pearl River, China: First insights into spatiotemporal distributions, compositions, sources and risks

Nanoplastics (NPs, size <1000 nm) are ubiquitous plastic particles, potentially more abundant than microplastics in the environment; however, studies highlighting their distribution dynamics in freshwater are rare due to analytical limitations. Here, we investigated spatiotemporal levels of nine polymers of NPs in surface water samples (n = 30) from the full stretch of the Pearl River (sites, n = 15) using pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). Six polymers were detected, including polystyrene (PS), polyvinyl chloride (PVC), nylon/polyamide 66 (PA66), polyester (PES), poly(methyl methacrylate) (PMMA) and polyethylene (PE), where three polymers showed high detection frequencies; PS (100 % in winter and summer), followed by PVC (73 % in winter and 87 % in summer) and PA66 (53 % in winter and 67 % in summer). The spatiotemporal distribution revealed the sites related to aquaculture (AQ) and shipping (SHP) showed higher NP levels than those of human settlement (HS) and wastewater treatment plants (WWTPs) (p = 0.004), and relatively high average levels of NPs in the urban sites compared to rural sites (p = 0.04), albeit showed no obvious seasonal differences (p = 0.78). For instance, the average PS levels in the Pearl River were in the following order: AQ 411.55 µg/L > SHP 81.75 µg/L > WWTP 56.66 µg/L > HS 47.75 µg/L in summer and HS 188.1 µg/L > SHP 103.55 µg/L > AQ 74.7 µg/L > WWTP 62.1 µg/L in winter. Source apportionment showed a higher contribution through domestic plastic waste emissions among urban sites, while rural sites showed an elevated contribution via aquaculture, agriculture, and surface run-off to the NP pollution. Risk assessment revealed that NPs at SHP and AQ sites posed a higher integrated risk in terms of pollution load index (PLI) than those at WWTP and HS sites. Regarding polymer hazard index (HI), 80 % of sampling sites in summer and 60 % of sampling sites in winter posed level III polymer risk, with PVC posing the highest risk. This study provides novel insights into the seasonal contamination and polymer risks of NP in the Pearl River, which will help to regulate the production and consumption of plastics in the region. Environmental ImplicationsThe contamination dynamics of field nanoplastics (NPs) in freshwater resources remain little understood, mainly attributed to analytical constraints. This study aims to highlight the spatiotemporal distribution of NPs in the Pearl River among various land use types, urban-rural comparison, seasonal comparison, their compositional profiles, potential sources, interaction with environmental factors, and ecological and polymer hazard assessments of investigated polymers in the full stretch of the Pearl River from Liuxi Reservoir to the Pearl River Delta (PRD) region. This study, with a comparatively large number of samples and NP polymers, will offer novel insights into the contamination profiles of nano-sized plastic particles in one of the important freshwater riverine systems in China.

Photoaged nanoplastics with multienzyme-like activities significantly shape the horizontal transfer of antibiotic resistance genes

Nanoplastics (NPs), identified as emerging pollutants, pose a great risk to environment and global public health, exerting profound influences on the prevalence and dissemination of antibiotic resistance genes (ARGs). Despite evidence suggesting that nano-sized plastic particles can facilitate the horizontal gene transfer (HGT) of ARGs, it is imperative to explore strategies for inhibiting the transfer of ARGs. Currently, limited information exists regarding the characteristics of environmentally aged NPs and their impact on ARGs propagation. Herein, we investigated the impact of photo-aged NPs on the transfer of ARG-carrying plasmids into Escherichia coli (E. coli) cells. Following simulated sunlight irradiation, photo-aged nano-sized polystyrene plastics (PS NPs) exhibited multiple enzyme-like activities, including peroxidase (POD) and oxidase (OXD), leading to a burst of reactive oxygen species (ROS). At relatively low concentrations (0.1, 1 μg/mL), both pristine and aged PS NPs facilitated the transfer of pUC19 and pHSG396 plasmids within E. coli due to moderate ROS production and enhanced cell membrane permeability. Intriguingly, at relatively high concentrations (5, 10 μg/mL), aged PS NPs significantly suppressed plasmids transformation. The non-unidirectional impact of aged PS NPs involved the overproduction of ROS (•OH and •O2−) via nanozyme activity, directly degrading ARGs and damaging plasmid structure. Additionally, oxidative damage to bacteria resulted from the presence of much toxic free radicals, causing physical damage to cell membranes, reduction of the SOS response and restriction of adenosine-triphosphate (ATP) supply, ultimately leading to inactivation of recipient cells. This study unveils the intrinsic multienzyme-like activity of environmentally aged NPs, highlighting their potential to impede the transfer and dissemination of ARGs.

Plastic particles affect N2O release via altering core microbial metabolisms in constructed wetlands

Constructed wetlands (CWs) have been proven to effectively immobilize plastic particles. However, little is known about the differences in the impact of varying sized plastic particles on nitrous oxide (N2O) release, as well as the intervention mechanisms in CWs. Here, we built a lab-scale wetland model and introduced plastic particles of macro-, micro-, and nano-size at 100 μg/L for 370 days. The results showed that plastic particles of all sizes reduced N2O release in CWs, with the degrees being the strongest for the Nano group, followed by Micro and Macro groups. Meanwhile, 15N- and 18O-tracing experiment revealed that the ammoxidation process contributed the most N2O production, followed by denitrification. While for every N2O-releasing process, the contributing proportion of N2O in nitrification-coupled denitrification were most significantly cut down under exposing to macro-sized plastics and had an obvious increase in nitrifier denitrification in all groups, respectively. Finally, we revealed the three mechanism pathways of N2O release reduction with macro-, micro-, and nano-sized plastics by impacting carbon assimilation (RubisCO activity), ammonia oxidation (gene amo abundance and HAO activity), and N-ion transmembrane and reductase activities, respectively. Our findings thus provided novel insights into the potential effects of plastic particles in CWs as an eco-technology.

Quantitation and identification of microplastics accumulation in human placental specimens using pyrolysis gas chromatography mass spectrometry.

The exponential increase in global plastic usage has led to the emergence of nano- and microplastic (NMP) pollution as a pressing environmental issue due to its implications for human and other mammalian health. We have developed methodologies to extract solid materials from human tissue samples by saponification and ultracentrifugation, allowing for highly specific and quantitative analysis of plastics by pyrolysis-gas chromatography and mass spectrometry (Py-GC-MS). As a benchmark, placenta tissue samples were analyzed using fluorescence microscopy and automated particle count, which demonstrated the presence of >1-micron particles and fibers, but not nano-sized plastic particles. Analyses of the samples (n = 10) using attenuated total reflectance-Fourier transform infrared spectroscopy indicated presence of rayon, polystyrene, polyethylene, and unclassified plastic particles. By contrast, among 62 placenta samples, Py-GC-MS revealed that microplastics were present in all participants' placentae, with concentrations ranging widely from 6.5 to 685 µg NMPs per gram of placental tissue, averaging 126.8 ± 147.5 µg/g (mean±SD). Polyethylene was the most prevalent polymer, accounting for 54% of total NMPs and consistently found in nearly all samples (mean 68.8 ± 93.2 µg/g placenta). Polyvinyl chloride and nylon each represented approximately 10% of the NMPs by weight, with the remaining 26% of the composition represented by 9 other polymers. Together, these data demonstrate advancements in the unbiased quantitative resolution of Py-GC-MS applied to the identification and quantification of NMP species at the maternal-fetal interface. This method, paired with clinical metadata, will be pivotal to evaluating potential impacts of NMPs on adverse pregnancy outcomes.

A mini-review on plasticrusts: occurrence, current trends, potential threats, and recommendations for coastal sustainability.

Plasticrusts manifest as a coating on intertidal rocks due to environmental exposure. They refer to crushed plastic debris that blankets rocks found along intertidal shorelines. This study significantly contributes to a better understanding of the occurrence of these novel plastic formations, shedding light on their potential pathways of formation during the Anthropocene era. The research provides comprehensive insights into the composition, origins, challenges, and effective management strategies for removing coastal plastic litter. The findings of this investigation offer valuable evidence regarding the formation and impact of these recently discovered plastic items in coastal regions, prompting discussions about their formation processes and their effects on the marine ecosystem. Recognizing that these newly emerged plastic litter pose a considerable threat to the marine environment is crucial. With their emergence, we face an environmental challenge, especially concerning the health of coastal ecosystems. Plasticrusts, when degraded, can release microplastics (MPs) and nanoparticles (NPs) into the surrounding environment. These micro- and nano-sized plastic particles pose significant ecological risks as they persist in ecosystems, potentially harming wildlife and entering the food chain, causing widespread environmental contamination. Significantly, it outlines strategies to minimize the impact of this emerging plastic debris and its source.

Toxicity of gold nanoparticles complicated by the co-existence multiscale plastics.

Gold nanoparticles (AuNPs) have been developed as treatment materials for various diseases and shown magnificent potential. By contrast to the broad toxicological studies on the single exposure (AuNPs), how the other health risks modulate the toxicological profile of AuNPs remains to be investigated. Plastics are among the most common health risks in daily life due to the broad utilization of plastic products. Therefore, in this study, we aimed to reveal the toxicological effects induced by co-exposure of gold nanorod (AuR) and polystyrene micro- and nano-plastics (hereinafter, referred to as AuRmPS and AuRnPS, respectively) in mice. Systematic biochemical characterizations were performed to investigate the hepatotoxicity, nephrotoxicity, neurotoxicity, inflammatory responses, alterations in gut microbiota induced by co-exposure, and to analyze the toxicological phenomena from the roles of reactive oxygen species and gut-organ axis. It has been found that hepatotoxicity, nephrotoxicity, neurotoxicity, and inflammation were exacerbated in AuRnPS and AuRmPS, and gut microbiota composition was more severely altered in AuRnPS exposure. These results suggest the necessity of reducing plastics exposure in AuNPs-based therapies. Moreover, protection against the nano-sized plastic particles holds higher priority. These findings will facilitate the explorations of methods to reduce therapeutic toxicity and improve biosafety for specific treatments by referring to the orders of importance in protecting different organs.

Addressing climate change mitigation: Implications for the sustainable alternatives to plastics

Abstract Accumulation of plastic waste is a global issue, and plastic particles are detected in different environments. The recent COVID-19 pandemic has been attributed to significant piling up of plastic waste and debris (including micro- and nano-sized plastic particles), yet the manufacturing of plastic products is still expected to grow. With the continuation of the COVID-19 pandemic, the use and disposal of plastics has resulted in increasing plastic pollution. There has been a lack of research into the effects of climate change on microplastics and, likewise, the effects of microplastics on climate change. This article aims to examine the pros and cons of sustainable alternatives to plastics in addressing the climate change issue. Special attention is devoted to the correlation between climate change and microplastic pollution. This perspective also serves to spawn ideas for mitigating greenhouse gas emissions caused by plastics by identifying the life cycle stages of plastic production.

Nanoplastics promote the dissemination of antibiotic resistance genes and diversify their bacterial hosts in soil

The wide application of plastics has led to the ubiquitous presence of nanoplastics and microplastics in terrestrial environments. However, few studies have focused on the mechanism underlying the effects of plastic particles on soil microbiomes and resistomes, especially the differences between nanoplastics and microplastics. This study investigated the microbiome and resistome in soil exposed to polystyrene microplastics (mPS) or nanoplastics (nPS) through 16S rRNA and shotgun metagenomic sequencing. Distinct microbial communities were observed between mPS and nPS exposure groups, and nPS exposure significantly changed the bacterial composition even at the lowest amended rate (0.01%, w/w). The abundance of antibiotic resistance genes (ARGs) in nPS exposure (1%) was 0.26 copies per cell, significantly higher than that in control (0.21 copies per cell) and mPS exposure groups (0.21 copies per cell). It was observed that nanoplastics, bacterial community, and mobile genetic elements (MGEs) directly affected the ARG abundance in nPS exposure groups, while in mPS exposure groups, only MGEs directly induced the change of ARGs. Streptomyces was the predominant host for multidrug in the control and mPS exposure, whereas the primary host was changed to Bacillus in nPS exposure. Additionally, exposure to nPS induced several bacterial hosts to exhibit possible multi-antibiotic resistance characteristics. Our results indicated that the effects of plastic particles on the soil microbial community were size-dependent, and nano-sized plastic particles exhibited more substantial impacts. Both microplastics and nanoplastics promoted ARG transfer and diversified their bacterial hosts. These findings bear implications for the regulation of plastic waste and ARGs.

New evidence of the presence of micro- and nanoplastic particles in bronchioalveolar lavage samples of clinical trial subjects

This is the first study reporting the presence of airborne nano-sized plastic particles in the bronchoalveolar lavage fluid (BALF) samples of patients undergoing diagnostic bronchoscopy. The results represent the plastic pollution content in the lower airways of the residents of Northern Europe. Airborne micro- and nanoplastic particles (MP/NPs) are widely dispersed worldwide and intrude on human organisms to various extents, with the respiratory tract being the first line of exposure. The amounts of inhaled MP/NPs, their fate in the human respiratory tract, and the effects on the health of human airways and other exposed organs remain largely unknown.In this clinical study, human BALF samples were assessed by means of optical and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM-EDX). Results show that MP/NPs levels vary in the interval of 0.14–12.8 particles per 100 ml of BALF and are present in all samples tested, mainly in a fragmented form. External pollution by MP/NPs was excluded by carefully choosing methodology and equipment. This finding is a timely addition of valuable information and stimulates further research into the biological effects of inhaled MP/NPs.

Optimization of experimental conditions for exposure of larval mussels (Mytilus californianus) to microplastic particles

Inputs of plastic pollution in marine environments continue to increase, making it essential to understand potential impacts on commercially important marine and estuarine species. Bivalve larvae have been shown to take up micro- and nano-sized plastics; however, exposures detailed in the literature often do not account for particle dynamics, such as eco-corona formation, agglomeration, or settlement. There is clearly a need to define and maintain suspended particle concentrations during exposure periods, while using culture systems that support the growth and survival of the test organism. Therefore, experiments were designed to optimize the components of an exposure system for both particle suspension, as well as larval mussel growth and survival. The suspension and clumping of 2 μm ultra-pure latex beads were assessed to determine the influence of flask shape, agitation, and dispersant type. These results were paired with an assessment of the effects of antibiotics, flask shape, flask rotation, and dispersant type on mussel larvae growth and survival. The combination of these experiments revealed that the optimum system for exposure of bivalve larvae to micro-sized plastics was in rotating, dimple-bottom flasks with additions of 2.5 mg.L−1 methyl cellulose and 2 mg.L−1 chloramphenicol in natural, 1 μm filtered seawater. This optimized system was used to assess the impacts of 2 μm ultra-pure latex beads on the survival and growth of Mytilus californianus larvae. First, a dose-response experiment was carried out to assess the impacts of a two-week exposure of larval mussels to microplastics concentrations that were 0%, 20%, 33.3%, 42.9%, and 50% of total cell volume of the algal ration. For these experiments the algal rations were all kept at 100%. Subsequently, a second experiment was carried out to assess impacts of a two-week exposure of larval mussels to microplastics where both the percent by volume of the algal (0–100%) ration and beads (0–100%) varied so that the total particle volume in the exposures remained constant (100% total). When algal food rations were held constant, a dose-dependent decrease in growth was observed with increasing concentrations of beads. When algal rations decreased, growth and survival decreased to a greater extent when microplastic beads were present. These results indicate that both concentrations of microplastic particles and volumetric ratios of algae rations to microplastic particles determine responses of mussel larvae, with microplastics having a greater effect on larval survival when added to low algal rations.

Intertwined synergistic abiotic and biotic degradation of polypropylene pellets in marine mesocosms

The accumulation of plastic waste in the oceans has caused growing concern for its effects on marine life. The interactions of plastics with environmental factors have been linked to fragmentation to micro- and nanoparticles with different properties and consequences, but the mechanism of fragmentation has not been fully understood yet. In this work, we investigate the combined effect of marine communities and ultraviolet (UV) radiation towards the degradation of virgin and artificially weathered polypropylene (PP) pellets after a long-term incubation period in marine mesocosms. The surface chemical alterations and deterioration of the polymer, in conjunction with the attachment and evolution of marine bacterial communities, the development of biofilm and exopolymeric substances (EPS), as well as the colloidal properties (zeta-potential and hydrodynamic diameter) of the mesocosms were studied. The surface area of both types of pellets decreased over time, despite no concrete weight change being observed. Cell growth, EPS production and colloid particle size were correlated to the loss of area. Therefore, we propose that surface area could be effectively monitored, instead of weight loss, as an alternative indicator of polymer degradation in biodegradation experiments. Changes in the chemical structure of the polymer, in addition to the evolution of the biological factors, implied that a complex degradation process alternated between two phases: an abiotic phase, when UV irradiation contributes to the deterioration of the polymer surface layers and a biotic phase, when marine communities degrade the weathered polymer surface to reveal the underlying layer of virgin polymer. Finally, microscopic particles, produced as a result of the decrease in pellet area, promoted the aggregation of colloidal particles. The role and impacts of these colloidal particles in marine ecosystems are yet as unidentified as that of micro- and nano-sized plastic particles and call for further investigation.

Evaluation of the nanoplastics removal by using starch-based coagulants: Roles of the chain architecture and hydrophobicity of the coagulant

Four starch-based coagulants with similar charge densities but different chain architectures and hydrophilicities were designed and fabricated. These are a linear and hydrophilic coagulant, St-CTA (Starch-3-chloro-2-hydroxypropyl triethyl ammonium chloride); a graft and hydrophilic coagulant, CS-AM-DMC (cationic starch-graft-poly[2-methacryloyloxyethyl trimethyl ammonium chloride and acrylamide]); and two graft and partially hydrophobic coagulants, CS-AM-DML (cationic starch-graft-poly[methacrylic acid 2-(benzyldimethylaminio) ethyl chloride and acrylamide]) and CS-AM-DMR (cationic starch-graft-poly[2-(methacryloyloxy)-N,N-dimethyl-N-alkyl ammonium chloride and acrylamide]) with aromatic and n-octane groups respectively. These starch-based coagulants in conjunction with polysilicic acid were employed in a current major environmental challenge which is to efficiently remove nano-sized plastics (NPs) from water. NPs of polystyrenes, polymethyl methacrylates and polyvinylchlorides were removed from different water sources under various conditions of pH and salinity. The effects of the chain architectures and hydrophilicities of the starch-based coagulants on the NPs removal have been investigated in detail. According to experimental evidence, three graft starch-based coagulants exhibited higher NPs removal efficiencies and better flocs properties than the linear St-CTA. This was attributed to the superiority of the graft chain architecture in the graft starch-based coagulants causing higher charge neutralization efficiencies in coagulative removal of NPs. In the three graft starch-based coagulants, CS-AM-DMR and CS-AM-DML with partially hydrophobic structures were more effectively to remove three NPs than CS-AM-DMC, and produced large, compact, durable and rapidly regrown flocs, due to the synergistic effects of charge neutralization and hydrophobic association. The interaction energies between NPs and the coagulants obtained from the extended Derjaguin-Landau-Verwey-Overbeek theory further confirmed that CS-AM-DMR and CS-AM-DML could achieve faster coagulation and thus higher efficiency in NPs removal. In addition, the NPs removal efficiency increased in acidic and highly saline solutions. These results obtained are of importance in guiding the design and selection of suitable polymeric coagulants for efficiently treating target contaminants in water.

Exposure to nanoplastics induces mitochondrial impairment and cytomembrane destruction in Leydig cells

Plastic particle pollution poses an emerging threat to ecological and human health. Laboratory animal studies have illustrated that nano-sized plastics can accumulate in the testis and cause testosterone deficiency and spermatogenic impairment. In this study, TM3 mouse Leydig cells were in vitro exposed to polystyrene nanoparticles (PS-NPs, size 20 nm) at dosages of 50, 100 and 150 μg/mL to investigate their cytotoxicity. Our results demonstrated that PS-NPs can be internalized into TM3 Leydig cells and led to a concentration-dependent decline in cell viability. Furthermore, PS-NPs stimulation amplified ROS generation and initiated cellular oxidative stress and apoptosis. Moreover, PS-NPs treatment affected the mitochondrial DNA copy number and collapsed the mitochondrial membrane potential, accompanied by a disrupted energy metabolism. The cells exposed to PS-NPs also displayed a down-regulated expression of steroidogenesis-related genes StAR, P450scc and 17β-HSD, along with a decrease in testosterone secretion. In addition, treatment with PS-NPs destructed plasma membrane integrity, as presented by increase in lactate dehydrogenase release and depolarization of cell membrane potential. In summary, these data indicated that exposure to PS-NPs in vitro produced cytotoxic effect on Leydig cells by inducing oxidative injury, mitochondrial impairment, apoptosis, and cytomembrane destruction. Our results provide new insights into male reproductive toxicity caused by NPs.

The contribution shift of ammonia-oxidizing archaea and bacteria to ammoxidation under Ag-NPs/SWCNTs/PS-NPs stressors in constructed wetlands

Ammonia-oxidizing microorganisms (AOMs, archaea (AOA) and bacteria (AOB)) are primarily responsible for the ammoxidation in constructed wetlands (CWs). However, little is known about evaluating the response of AOA and AOB to engineered nanomaterials (ENMs) and quantifying the shift of their contribution to ammoxidation. Herein, we operated a series of CWs exposing to silver nanoparticles (Ag-NPs), single-walled carbon nanotubes (SWCNTs), and polystyrene nano-sized plastics (PS-NPs) with the wastewater-accumulating concentration of ENMs for 180 days. The results showed that the abundance of AOA amoA gene in situ was far lower than that of AOB, while the abundance ratio of AOA to AOB increased by 15 folds after 180-day experiment. Using DNA stable isotope probing (DNA-SIP) experiment, we found that the active AOB microbiota varied substantially but the AOA was more stable across different groups. Furthermore, the co-occurrence analysis proved that ENMs stress increased the negative coexistence pattern of AOA and AOB; predictive functional profiling showed that the ENMs enhanced the functional advantage of AOA by inhibiting AOB (mainly hydroxylamine oxidation process). Finally, the contribution of AOA increased under exposing to SWCNTs (18.35%), PS-NPs (24.92%), and Ag-NPs (32.14%) compared with control group (0.03%) for 180 days. Despite this, AOB was still the primary executant of ammoxidation in CWs. Overall, in our study, the differences in activities and contributions of AOMs were quantified in CWs, and a significantly negative coexistence relationship between AOA and AOB was revealed when exposed to emerging nanomaterials.

Identification of microplastics from urban informal solid waste landfill soil; MP associations with COD and chloride.

Microplastics (MPs) are an issue of prime environmental concern globally. The abundance of MP particles in the informal open solid waste landfill soil was evaluated showing 180-1120 MP particles per kg of soil. Moisture content (MC), electrical conductivity (EC) and pH of the MP-contaminated soil compared to the baseline showed 2.96% MC, 187-441 μS/cm EC and 6.94 pH. Morphology of extracted MPs in SEM showed particle fragmentation as film fragments (13.7%), fragments (56.1%), fibres (26.4%) and foam (3.8%). EDS results showed Carbon 71.8% and 24.5% oxygen with traces of Na, Al, Si and Cl-. FTIR of field obtained MPs identified were polyethylene and polypropylene. The association of MP particles with COD and chloride was discovered. MP particles of Low-density Polyethylene of size of 1 mm × 1 mm and thickness 25 μm up to 20 numbers showed no effect adding to the COD values. The COD values increased with increase in MP particle numbers. Similarly, chloride associations with MP particles showed an increase in MP particles reducing chloride values by 31% in landfill runoff water. It is interpreted that MP particle disintegration into nano-sized plastics (NPs) in the soil/runoff water can greatly increase the COD values and impair the salt mass balance.

Raman imaging to capture microplastics and nanoplastics carried by smartphones

The sources of microplastics and nanoplastics can be found almost everywhere, including being released from the activities of our daily lives. Unfortunately, the process for determining the sources of microplastics and nanoplastics is hampered by the limited techniques available for characterisation. Herewith, we advance Raman imaging by combining it with logic-based, algebra-based, PCA-based algorithms and their hybrid, which can significantly increase the signal-noise ratio and the imaging certainty, to enable the characterisation of microplastics. Consequently, we can capture and identify the microplastics carried by our smartphones. That is because, due to the friction and fragmentation etc., our clothes and the decoration trinkets that might be made of plastic fibres can release microplastics. The released microplastics stick on the phone surface, or are trapped in the charging port, speaker ports etc., towards accumulation. We estimate hundreds or thousands of microplastics can be captured and carried by a smartphone, depending on the clothing materials, pocketing styles, user habits etc. Due to the complexity of the samples (which shields the weak signals emitted from nanoplastics), further methodological improvements are required, such as optimisation of sample preparation (for better isolation of nano-sized plastics), refinement of data processing algorithms and combined use of Raman microscopy and scanning electron microscopy (SEM).

Evaluation of nanoplastics toxicity in the soil nematode Caenorhabditis elegans by iTRAQ-based quantitative proteomics

Plastic pollution is recognized as a major threat to ecosystems in the 21st century. Large plastic objects undergo biotic and abiotic degradation to generate micro- and nano-sized plastic pieces. Despite tremendous efforts to evaluate the adverse effects of microplastics, a comprehensive understanding of the toxicity of nanoplastics remains elusive, especially at the protein level. To this end, we used isobaric-tag-for-relative-and-absolute-quantitation-based quantitative proteomics to investigate the proteome dynamics of the soil nematode Caenorhabditis elegans in response to exposure to 100 nm polystyrene nanoplastics (PS-NPs). After 48 h of exposure to 0.1, 1, or 10 mg/L PS-NPs, 136 out of 1684 proteins were differentially expressed and 108 of these proteins were upregulated. These proteins were related to ribosome biogenesis, translation, proteolysis, kinases, protein processing in the endoplasmic reticulum, and energy metabolism. Remarkably, changes in proteome dynamics in response to exposure to PS-NPs were consistent with the phenotypic defects of C. elegans. Collectively, our findings demonstrate that disruption of proteome homeostasis is a biological consequence of PS-NPs accumulation in C. elegans, which provides insights into the molecular mechanisms underlying the toxicology of nanoplastics.