A novel extraction protocol of nano-polystyrene from biological samples

Unraveling the micro- and nanoplastic predicament: A human-centric insight

Micro- and nanoplastics are vast anthropogenic pollutants in our direct surroundings with a robust environmental stability and a potential for a long-lasting and increasing global circulation. This has raised concerns among the public and policy makers for human health upon exposure to these particles. The micro- and nanoplastic burden on humans is currently under debate, along with criticism on the experimental approaches used in hazard assessment. The present review presents an overview of the human-relevant aspects associated with the current micro-and nanoplastic burden. We focus on environmental circulation and the estimation of exposure quantities to humans, along with a state-of-the-art overview of particle accumulation in over 15 human organs and other specimen. Additionally, data regarding particle characteristics used in toxicity testing was extracted from 91 studies and discussed considering their environmental and human relevance.

Nanoplastic propels diet-induced NAFL to NASH via ER-mitochondrial tether-controlled redox switch

Nonalcoholic steatohepatitis (NASH) is multifactorial that lifestyle, genetic, and environmental factors contribute to its onset and progression, thereby posing a challenge for therapeutic intervention. Nanoplastic (NP) is emerged as a novel environmental metabolism disruptor but the etiopathogenesis remains largely unknown. In this study, C57BL/6 J mice were fed with normal chow diet (NCD) and high-fat diet (HFD) containing 70 nm polystyrene microspheres (NP). We found that dietary-derived NP adsorbed proteins and agglomerated during the in vivo transportation, enabling diet-induced hepatic steatosis to NASH. Mechanistically, NP promoted liver steatosis by upregulating Fatp2. Furthermore, NP stabilized the Ip3r1, and facilitated ER-mitochondria contacts (MAMs) assembly in the hepatocytes, resulting in mitochondrial Ca2+ overload and redox imbalance. The redox-sensitive Nrf2 was decreased in the liver of NP-exposed mice, which positively regulated miR26a via direct binding to its promoter region [-970 bp to -847 bp and -318 bp to -176 bp]. NP decreased miR26a simultaneously upregulated 10 genes involved in MAMs formation, lipid uptake, inflammation, and fibrosis. Moreover, miR26a inhibition elevated MAMs-tether Vdac1, which promoted the nucleus translocation of NF-κB P65 and Keap1 and functionally inactivated Nrf2, leading to a vicious cycle. Hepatocyte-specific overexpressing miR26a effectively restored ER-mitochondria miscommunication and ameliorated NASH phenotype in NP-exposed and Keap1-overexpressed mice on HFD. The hepatic MAM-tethers/Nrf2/miR26a feedback loop is an essential metabolic switch from simple steatosis to NASH and a promising therapeutic target for oxidative stress-associated liver damage and NASH.

Size-dependent toxicity of polystyrene microplastics on the gastrointestinal tract: Oxidative stress related-DNA damage and potential carcinogenicity

Microplastics (MPs) and nanoplastics (NPs) have been generally regarded as emerging pollutants and received worldwide attention in recent years. Water and food consumption are the primary pathways for human exposure to MPs/NPs, thus gastrointestinal tracts may be susceptible to their toxicity. Although the recent report has indicated the presence of MPs/NPs in multiple human organs, little is known about their gastric effects. Therefore, this study focused on the adverse effects of polystyrene microplastics (PS-MPs) on gastric epithelium in vivo and in vitro. Surface-enhanced Raman spectroscopy (SERS) revealed the distribution of PS-MPs was associated with their particle sizes, and predominantly concentrated in gastric tissues. Gastric barrier injury and mitochondrial damage were observed in rats after exposure to PS-MPs. Compared with the larger ones, polystyrene nanoplastics (PS-NPs) more significantly reduced the activity of antioxidant enzymes while enhancing the level of MDA, 8-OhdG and γ-H2AX. Meanwhile, PS-MPs caused upregulation of β-catenin/YAP through redox-dependent regulation of nucleoredoxin (NXN) and dishevelled (Dvl). These findings supported the size-dependent effects of PS-MPs on oxidative stress and DNA damage. Moreover, the redox-dependent activation of the β-catenin/YAP cascade suggested a novel toxic mechanism for PS-MPs and implied the potential carcinogenic effects.

Research advances of microplastics and potential health risks of microplastics on terrestrial higher mammals: a bibliometric analysis and literature review

Microplastics (MPs) have become increasingly serious global problems due to their wide distribution and complicated impacts on living organisms. To obtain a comprehensive overview of the latest research progress on MPs, we conducted a bibliometric analysis combined with a literature review. The results showed that the number of studies on MPs has grown exponentially since 2010. Recently, the hotspot on MPs has shifted to terrestrial ecosystems and biological health risks, including human health risks. In addition, the toxic effects, identification and quantification of MPs are relatively new research hotspots. We subsequently provide a review of MPs studies related to health risks to terrestrial higher mammals and, in particular, to humans, including detection methods and potential toxicities based on current studies. Currently, MPs have been found existing in human feces, blood, colon, placenta and lung, but it is still unclear whether this is associated with related systemic diseases. In vivo and in vitro studies have demonstrated that MPs cause intestinal toxicity, metabolic disruption, reproductive toxicity, neurotoxicity, immunotoxicity through oxidative stress, apoptosis and specific pathways, etc. Notably, in terms of combined effects with pollutants and neurotoxicity, the effects of MPs are still controversial. Future attention should be paid to the detection and quantification of MPs in human tissues, exploring the combined effects and related mechanisms of MPs with other pollutants and clarifying the association between MPs and the development of pre-existing diseases. Our work enhances further understanding of the potential health risks of MPs to terrestrial higher mammals.

Raman spectra characterization of size-dependent aggregation and dispersion of polystyrene particles in aquatic environments

Aqueous environments are generally thought to be a source of pooling and re-distribution for both micro-plastics (MPs) and nano-plastics (NPs); however, significantly less data on NPs than MPs have been reported. The occurrence of salts, proteins, and other organic matter may promote or inhibit the aggregation of NPs to form agglomeration particles, making their detection more difficult. In this study, 80 and 500 nm polystyrene nano-plastics (PS-NPs) modified by four different functional groups (PS-Bare, PS-COOH, PS-NH₂, and PS-CHO-500 nm) were selected to mimic the flocculation and/or sedimentation of NPs in salts (NaCl, CaCl₂, and Na₂SO₄) and protein solutions. The results showed that the 80 nm PS-NPs are only colloidal in pure water. All four strong electrolyte solutions that were tested significantly promoted the aggregation of PS-NPs, including those that were protein-coated. In addition, 500 nm PS-CHO did not flocculate but gradually settled into sedimentation. Therefore, Raman spectrometry can be used to analyze assembled PS-NPs, but is not suitable for analyzing normal PS-NPs. By combining fractal morphology, this study provides insight into the comprehensive analysis of PS-NPs in water solutions, including the digestion of biological samples.

Nanoplastics: Status and Knowledge Gaps in the Finalization of Environmental Risk Assessments

Nanoplastics (NPs) are particles ranging in size between 1 and 1000 nm, and they are a form of environmental contaminant of great ecotoxicological concern. Although NPs are widespread across ecosystems, they have only recently garnered growing attention from both the scientific community and regulatory bodies. The present study reviews scientific literature related to the exposure and effects of NPs and identifies research gaps that impede the finalization of related environmental risk assessments (ERAs). Approximately 80 articles published between 2012 and 2021 were considered. Very few studies (eight articles) focused on the presence of NPs in biotic matrices, whereas the majority of the studies (62 articles) assessed the lethal and sublethal effects of NPs on aquatic and terrestrial organisms. Whilst many studies focused on nude NPs, only a few considered their association with different aggregates. Amongst NPs, the effects of polystyrene are the most extensively reported to date. Moreover, the effects of NPs on aquatic organisms are better characterized than those on terrestrial organisms. NP concentrations detected in water were close to or even higher than the sublethal levels for organisms. An ERA framework specifically tailored to NPs is proposed.

Extraction method development for nanoplastics from oyster and fish tissues

Nanoplastics are now found in some environmental media and consumer products. However, very limited data on nanoplastics are available for one of the main human consumption sources of microplastics: seafood. Unlike microplastics, a method for extracting nanoplastics from seafood is still lacking. Herein, a combination of common extraction techniques including enzymatic digestion, sequential membrane filtration, centrifugal concentration, and purification (dialysis and sodium dodecylsulfate (SDS) incubation), was developed to extract nanoplastics from oyster and fish tissues. Corolase with subsequent lipase treatment achieved the highest digestion efficiencies (88- 89%) for non-homogenized tissues compared to other proteases and additional cellulase or H₂O₂ treatment. With the exception of polyethylene terephthalate (PET), enzymatic digestion did not change the morphology or structure of polyvinyl chloride (PVC), polyethylene (PE), or polystyrene (PS) nanoplastic particles, and the subsequent extraction procedures had good recoveries of 71- 110% for fluorescence-labeled 76-nm PVC and 100- and 750-nm PS, as validated by a Nanoparticle Tracking Analysis (NTA). Few of the 10¹¹ digested residual particles of 150- 300 nm in diameter per oyster or per serving of fish tissue were left in the method blank. Consequently, this efficient approach could be used as a pretreatment protocol for current potential nanoplastic detection methods.

Size-dependent effects of polystyrene nanoplastics on autophagy response in human umbilical vein endothelial cells

Ubiquitous nanoplastics (NPs) increase exposure risks to humans through the food chain and/or other ways. However, huge knowledge gaps exist regarding the fate and adverse impact of NPs on the human cardiovascular system. Autophagy is an important catabolic pathway that disposes of cytoplasmic waste through the lysosomes. In this study, we pursued to determine the interaction and autophagy effect of polystyrene nanoplastics (PS-NPs) (100 and 500 nm in size) on human umbilical vein endothelial cells (HUVECs). The results showed both sizes of PS-NPs interacted with almost all the treated HUVECs in a time- and concentration-dependent manner, and 500 nm PS-NPs were only bound to the surface of cell membranes, whereas 100 nm PS-NPs were taken up by HUVECs and aggregated in the cytoplasm. Furthermore, exposure to 25 μg/mL of 500 nm PS-NPs for 48 h significantly increased lactate dehydrogenase release from HUVECs, while internalized 100 nm PS-NPs not only caused cell membrane damage, but also induced autophagy initiation and autophagosome formation. By a mCherry-GFP-LC3 lentivirus infection assay, we also demonstrated that autophagic flux level was impaired in response to 100 nm PS-NPs. Herein, our results provide new insight into the size-dependent internalization and autophagy response to PS-NPs in HUVECs.

Environmental microplastic and nanoplastic: Exposure routes and effects on coagulation and the cardiovascular system

Plastic pollution has been a growing concern in recent decades due to the proliferation and ease of manufacturing of single use plastic products and inadequate waste and recycling management. Microplastic, and even smaller nanoplastic, particles are persistent pollutants in aquatic and terrestrial systems and are the subject of active and urgent research. This review will explore the current research on how exposure to plastic particles occurs and the risks associated from different exposure routes: ingestion, inhalation, and dermal exposure. The effects of microplastics on the cardiovascular system are of particular importance due to its sensitivity and ability to transport particles to other organ systems. The effects of microplastics and nanoplastics on the heart, platelet aggregation, and thrombus formation will all be explored with focus on how the particle characteristics modulate their effect. Plastic particle interactions are highly dependent on both their size and their surface chemistry and interesting research is being done with the interaction of particle characteristics and effect on thrombosis and the cardiovascular system. There is significant uncertainty surrounding some of the findings in this field as research in this area is still maturing. There are undoubtedly more physiological consequences than we are currently aware of resulting from environmental plastic exposure and more studies need to be conducted to reveal the full extent of pathologies caused by the various routes of microplastic exposure, with particular emphasis on longitudinal exposure effects. Further research will allow us to recognize the full extent of physiological impact and begin developing viable solutions to reduce plastic pollution and potentially design interventions to mitigate in-vivo plastic effects following significant or prolonged exposure.