Polystyrene polymers cause severe toxicity to aquatic animals. However, the process and mechanisms of innate immunity of invertebrates living at the bottom of the food chain to these pollutants remain unclear. In this study, the blood system responses of zooplankton Artemia were assessed through in vivo and in vitro exposure to amino-modified polystyrene nanoplastics (PS-NH2 NPs). The results indicated that the LC50 values of PS-NH2 NPs were 1.09 μg·mL-1 over 48 h and 0.42 μg·mL-1 over 7 d. Based on the five hemocyte subpopulations identified in Artemia, in vitro exposure assays revealed that phagocytosis was performed by plasmocytes and granulocytes with phagocytic rate of 22.64 %. TEM analysis further showed that PS-NH2 NPs caused cytoplasm vacuolization, swollen mitochondria, and lipid processing disorder. Gene expression pattern results demonstrated that Spatzle, Tollip, Hsp70, Hsp90, Casp8, API5and Pxn were significantly upregulated upon acute and chronic exposure (p < 0.05), while chronic exposure could induce significantly upregulation of ProPO (p < 0.05). Moreover, PS-NH2 NPs exposure remarkably varied the hemolymph microbiota and hemogram, particularly by increasing the proportion of adipohemocytes and phagocytes (p < 0.05). Our findings suggest that PS-NH2 NPs induce different responses in Artemia hemocyte, as primarily reflected by phagocytic processes, expression of immune and apoptosis relating genes, cell fates, hemogram and hemolymph microbiota variations. These findings support the possibility of using Artemia hemocytes as bioindicator to estimate nanoplastics pollution, thus contributing to hematological toxicity research in response to nanoplastics.

Increasing attention is being paid to the toxic physiological effects of nanoplastics (NPs) on aquatic organisms. However, few studies have systematically evaluated the regulatory mechanisms of NPs on immune response in crustaceans. In this study, a 28-day chronic exposure experiment was conducted in which shrimps were exposed to various 80-nm polystyrene NPs concentrations (0, 0.1, 1, 5 and 10 mg/L). Transcriptomic analysis was used to investigate the regulatory mechanisms of NPs in immune response of Litopenaeus vannamei. With increasing NPs concentration, the total hemocyte count (THC) content decreased, while phagocytosis rate (PR) and respiratory burst (RB) showed trends of first rising and then falling. High concentration (10 mg/L) of NPs caused the destruction of hepatopancreas tissue structure, the shedding of microvilli, the increase number of hepatocyte apoptosis and autophagy structure. With increasing NPs concentration, the lysozyme (Lys), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities first increased and then decrease, while contents of lipid peroxidation and malondialdehyde increased; the expression levels of Toll, MyD88, GPx, SOD, proPO, Lys, and ALF generally increased at first and then decreased. Transcriptional sequencing analysis showed that the pathway of differentially expressed genes in KEGG enrichment mainly included lysosome (ko04142), apoptosis (ko04210) pathways, indicating that the NPs mainly affected the immune regulatory mechanism. Further analysis by Gene Set Enrichment Analysis (GSEA) showed that the up-regulation pathways of NPs activation mainly included immune response-related pathways such as mitochondrial autophagy, DNA repair, autophagosomes signaling pathway. Our results indicated that NPs exposure induced oxidative stress, apoptosis and autophagy in shrimps. This study provides a basis for further understanding of the mechanisms of antioxidant immune regulation by NPs in shrimp and may serve as a reference for healthy ecological culture of shrimp.

Microplastics and nanoplastics have been an emerging global concern, with hazardous effects on plant, animal, and human health. Their small size makes it easier for them to spread to various ecosystems and enter the food chain; they are already widely found in aqueous environments and within aquatic life, and have even been found within humans. Much research has gone into understanding micro-/nanoplastic sources and environmental fate, but less work has been done to understand their degradation. Photocatalytic degradation is a promising green technique that uses visible or ultraviolet light in combination with photocatalyst to degrade plastic particles. While complete degradation, reducing plastics to small molecules, is often the goal, partial degradation is more common. We examined microscale polyethylene (125-150 µm in diameter) and nanoscale polystyrene (~300 nm in diameter) spheres both before and after degradation using multiple imaging techniques, especially scanning electron microscopy and electron tomography. Electron tomography is able to image the 3D exterior and interior of the nanoplastics, enabling us to observe within aggregates and inside degraded spheres, where we found potentially open interior structures after degradation. These structures may result from differences in degradation and aggregation behaviour between the different plastic types, with our work finding that polyethylene microplastics typically cracked into sharp fragments, while polystyrene nanoplastics often fragmented into smoother, more curved shapes. These and other differences, along with interior and 3D surface images, provide new details on how the structure and aggregation of polyethylene microplastics and polystyrene nanoplastics changes when degraded, which could influence how the resulting worn particles are collected or treated further.

Oxidative stress is a universal interpretation for the toxicity mechanism of nanoplastics to microalgae. However, there is a lack of deeper insight into the regulation mechanism in microalgae response to oxidative stress, thus affecting the prevention and control for nanoplastics hazard. The integrated analysis of transcriptomics and metabolomics was employed to investigate the mechanism for the oxidative stress response of Chlorella pyrenoidosa to nanoplastics and subsequently lock the according core pathways and driver genes induced. Results indicated that the linoleic acid metabolism, glycine (Gly)-serine (Ser)-threonine (Thr) metabolism, and arginine and proline metabolism pathways of C. pyrenoidosa were collectively involved in oxidative stress. The analysis of linoleic acid metabolism suggested that nanoplastics prompted algal cells to secrete more allelochemicals, thereby leading to destroy the immune system of cells. Gly-Ser-Thr metabolism and arginine and proline metabolism pathways were core pathways involved in algal regulation of cell membrane function and antioxidant system. Key genes, such as LOX2.3, SHM1, TRPA1, and proC1, are drivers of regulating the oxidative stress of algae cells. This investigation lays the foundation for future applications of gene editing technology to limit the hazards of nanoplastics on aquatic organism.

The presence in seawater of low-molecular-weight polyethylene (PE) and polydimethylsiloxane (PDMS), synthetic polymers with high chemical resistance, has been demonstrated in this study for the first time by developing a novel methodology for their recovery and quantification from surface seawater. These synthetic polymer debris (SPD) with very low molecular weights and sizes in the nano- and micro-metre range have escaped conventional analytical methods. SPD have been easily recovered from water samples (2 L) through filtration with a nitrocellulose membrane filter with a pore size of 0.45 μm. Dissolving the filter in acetone allowed the isolation of the particulates by centrifugation followed by drying. The isolated SPD were analysed by 1H nuclear magnetic resonance spectroscopy (1H NMR), identifying PE and PDMS. These polymers are thus persisting on seawater because of their low density and the ponderal concentrations were quantified in mg/m3. This method was used in an actual case study in which 120 surface seawater samples were collected during two sampling campaigns in the Mediterranean Sea (from the Gulf of Salerno to the Gulf of Policastro in South Italy). The developed analytical protocol allowed achieving unprecedented simplicity, rapidity and sensitivity. The 1H and 13C NMR structural analysis of the PE debris indicates the presence of oxidised polymer chains with very low molecular weights. Additionally, the origin of those low molecular weight polymers was investigated by analysing influents and effluents from a wastewater treatment plant (WWTP) in Salerno as a hot spot for the release of SPD: the analysis indicates the presence of low molecular weight polymers compatible with wax-PE, widely used for coating applications, food industry, cosmetics and detergents. Moreover, the origin of PDMS debris found in surface seawater can be ascribed to silicone-based antifoamers and emulsifiers.

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 IMPLICATIONS: The 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.

Nanoplastics (NPs) present a hidden risk to organisms and the environment via migration and enrichment. Detecting NPs remains challenging because of their small size, low ambient concentrations, and environmental variability. There is an urgency to exploit detection approaches that are more compatible with real-world environments. Herein, this study provides a surface-enhanced Raman spectroscopy (SERS) technique for the in situ reductive generation of silver nanoparticles (Ag NPs), which is based on photoaging-induced modifications in NPs. The feasibility of generating Ag NPs on the surface of NPs was derived by exploring the photoaging mechanism, which was then utilized to SERS detection. The approach was applied successfully for the detection of polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) NPs with excellent sensitivity (e.g., as low as 1 × 10-6 mg/mL for PVC NPs, and an enhancement factor (EF) of up to 2.42 × 105 for small size PS NPs) and quantitative analytical capability (R2 > 0.95579). The method was successful in detecting NPs (PS NPs) in lake water. In addition, satisfactory recoveries (93.54-105.70 %, RSD < 12.5 %) were obtained by spiking tap water as well as lake water, indicating the applicability of the method to the actual environment. Therefore, the proposed approach offers more perspectives for testing real environmental NPs.

Nanoplastics (NPs), as emerging contaminants, have been shown to cause testicular disorders in mammals. However, whether paternal inheritance effects on offspring health are involved in NP-induced reproductive toxicity remains unclear. In this study, we developed a mouse model where male mice were administered 200 nm polyethylene nanoparticles (PE-NPs) at a concentration of 2 mg/L through daily gavage for 35 days to evaluate the intergenerational effects of PE-NPs in an exclusive male-lineage transmission paradigm. We observed that paternal exposure to PE-NPs significantly affected growth phenotypes and sex hormone levels and induced histological damage in the testicular tissue of both F0 and F1 generations. In addition, consistent changes in sperm count, motility, abnormalities, and gene expression related to endoplasmic reticulum stress, sex hormone synthesis, and spermatogenesis were observed across paternal generations. The upregulation of microRNA (miR)-1983 and the downregulation of miR-122-5p, miR-5100, and miR-6240 were observed in both F0 and F1 mice, which may have been influenced by reproductive signaling pathways, as indicated by the RNA sequencing of testis tissues and quantitative real-time polymerase chain reaction findings. Furthermore, alterations in the gut microbiota and subsequent Spearman correlation analysis revealed that an increased abundance of Desulfovibrio (C21_c20) and Ruminococcus (gnavus) and a decreased abundance of Allobaculum were positively associated with spermatogenic dysfunction. These findings were validated in a fecal microbiota transplantation trial. Our results demonstrate that changes in miRNAs and the gut microbiota caused by paternal exposure to PE-NPs mediated intergenerational effects, providing deeper insights into mechanisms underlying the impact of paternal inheritance.

Nanoplastics are difficult to remove from water using conventional flotation processes due to their stability and resistance to biodegradation. Here, polystyrene nanoplastics (PSNPs) were selected as the object of study. In addition, chitosan (CTS), an environmentally friendly natural cationic polymer, was selected to modify the air flotation process to improve the separation of PSNPs using air flotation. Adding chitosan effectively enhanced the removal of PSNPs using air flotation from 3.1 % to 96.7 %. The residual concentration decreased from 9.69 mg/L to 0.33 mg/L. Removal of PSNPs by CTS-modified air flotation was maintained at 92.8 % even when the air flotation time was significantly shortened. The zeta potential alterations demonstrated robust electrostatic attraction within the CTS-modified air flotation process. The contact angle measurements indicated that incorporating CTS could enhance the hydrophobic interaction between bubbles and PSNPs. PSNPs particles around 100 nm agglomerated to form floating flocs with a particle size of more than 4500 nm. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) images confirmed the presence of tight adhesion between PSNPs and CTS, indicating the presence of bridging adsorption during the process. The major PSNPs removal mechanisms included electrostatic attraction, enhancement of hydrophobicity, and bridging adsorption. Increasing the aeration volume could improve the removal rate, but this improvement was finite. Weakly acidic and low ionic strength conditions favored PSNPs removal. The CTS-modified air flotation process showed great potential for PSNPs removal from real water bodies.

Transgenerational nanoplastic toxicity could be detected in Caenorhabditis elegans after exposure at the parental generation (P0-G); however, the underlying mechanisms remain largely unclear. We aimed to examine the role of germline nuclear hormone receptors (NHRs) in controlling the transgenerational toxicity of polystyrene nanoparticles (PS-NPs) based on gene expression screening and functional analysis. Among germline NHR genes, daf-12, nhr-14, and nhr-47 expressions were increased and nhr-12 expression was decreased by PS-NPs (1 and 10 μg/L). Transgenerational alterations in expressions of these four NHR genes were also induced by PS-NPs (1 and 10 μg/L). RNAi of daf-12, nhr-14, and nhr-47 caused resistance, whereas RNAi of nhr-12 conferred susceptibility to transgenerational PS-NP toxicity. After PS-NP exposure, expressions of ins-3, daf-28, and ins-39 encoding insulin ligands, efn-3 encoding Ephrin ligand, and lin-44 encoding Wnt ligand, as well as expressions of their receptor genes (daf-2, vab-1, and/or mig-1), were dysregulated by the RNAi of daf-12, nhr-14, nhr-47, and nhr-12. Therefore, alteration in certain germline NHRs could mediate the induction of transgenerational nanoplastic toxicity by affecting secreted ligands and their receptors in the offspring of exposed organisms.