Materials, surfaces, and interfacial phenomena in nanoplastics toxicology research

The size-dependent effects of nanoplastics in mouse primary hepatocytes from cells to molecules

Nanoplastics (NPs) are easily ingested by organisms and their major accumulation organ was determined to be liver. To date, the size-dependent cytotoxicity of NPs on mammalian hepatocytes remains unclear. This study utilized mouse primary hepatocytes and catalase (CAT) as specific receptors to investigate the toxicity of NPs from cells to molecules, focusing on size-dependent effects. Results showed that the larger the particle size of NP at low doses (≤50 mg/L), the most pronounced inhibitory effect on hepatocyte viability. 20 nm NPs significantly inhibit cell viability only at high doses (100 mg/L). Larger NP particles (500 nm and 1000 nm) resulted in a massive release of lactate dehydrogenase (LDH) from the cell (cell membrane damage). Reactive oxygen species (ROS), superoxide dismutase (SOD) and CAT tests suggest that NPs disturbed the cellular antioxidant system. 20 nm NPs show great strength in oxidizing lipids and disrupting mitochondrial function compared to NPs of other particle sizes. The degree of inhibition of CAT activity by different sized NPs was coherent at the cellular and molecular levels, and NP-500 had the most impact. This suggests that the structure and microenvironment of the polypeptide chain in the vicinity of the CAT active site is more susceptible to proximity and alteration by NP-500. In addition, the smaller NPs are capable of inducing relaxation of CAT backbone, disruption of H-bonding and reduction of α-helix content, whereas the larger NPs cause contraction of CAT backbone and increase in α-helix content. All NPs induce CAT fluorescence sensitization and make the chromophore microenvironment hydrophobic. This study provides new insights for NP risk assessment and applications.

Polystyrene nanoplastics distinctly impact cadmium uptake and toxicity in Arabidopsis thaliana

The ubiquitous presence of micro- and nanoplastics (MNPs) in soil has raised concerns regarding their potential effects on terrestrial plants. The coexistence and interactions between MNPs and heavy metals altering their phytotoxicity deserves further investigation. In this study, we explored the impacts of various concentrations of polystyrene nanoplastics (PS-NPs) and cadmium (Cd) alone or in combination on the growth and development of Arabidopsis thaliana. Additionally, we examined the effects of combined stress on the uptake and translocation of Cd within Arabidopsis thaliana. Our findings revealed several key insights: PS-NPs exhibited the capability to internalize in the maturation zone of Arabidopsis roots; the presence of Cd changed the particle size and zeta potential of PS-NPs; the presence of PS-NPs heightened Cd accumulation in the underground parts of Arabidopsis seedlings, leading to a stronger oxidative stress response in these regions; the composite stress exerted a more pronounced effect on the growth and development of Arabidopsis compared to individual stresses. Interestingly, while higher PS-NPs concentrations hindered Cd migration from roots to leaves, they also acted as carriers for Cd uptake in Arabidopsis roots. These findings shed light on the combined impacts of MNPs and heavy metals on plant physiology, offering theoretical insights to guide risk assessment strategies for MNPs and heavy metals in terrestrial ecosystems.

Probing Long-Term Impacts: Low-Dose Polystyrene Nanoplastics Exacerbate Mitochondrial Health and Evoke Secondary Glycolysis via Repeated and Single Dosing

Nanoplastics (NPs) are omnipresent in the environment and contribute to human exposure. However, little is known regarding the long-term effects of NPs on human health. In this study, human intestinal Caco-2 cells were exposed to polystyrene nanoplastics (nanoPS) in an environmentally relevant concentration range (102-109 particles/mL) under two realistic exposure scenarios. In the first scenario, cells were repeatedly exposed to nanoPS every 2 days for 12 days to study the long-term effects. In the second scenario, only nanoPS was added once and Caco-2 cells were cultured for 12 days to study the duration of the initial effects of NPs. Under repeated dosing, initial subtle effects on mitochondria induced by low concentrations would accrue over consistent exposure to nanoPS and finally lead to significant impairment of mitochondrial respiration, mitochondrial mass, and cell differentiation process at the end of prolonged exposure, accompanied by significantly increased glycolysis over the whole exposure period. Single dosing of nanoPS elicited transient effects on mitochondrial and glycolytic functions, as well as increased reactive oxygen species (ROS) production in the early phase of exposure, but the self-recovery capacity of cells mitigated these effects at intermediate culture times. Notably, secondary effects on glycolysis and ROS production were observed during the late culture period, while the cell differentiation process and mitochondrial mass were not affected at the end. These long-term effects are of crucial importance for comprehensively evaluating the health hazards arising from lifetime exposure to NPs, complementing the extensively observed acute effects associated with prevalent short-term exposure to high concentrations. Our study underlines the need to study the toxicity of NPs in realistic long-term exposure scenarios such as repeated dosing.

Manganese dioxide nanoparticles provoke inflammatory damage in BV2 microglial cells via increasing reactive oxygen species to activate the p38 MAPK pathway

With the widespread use of manganese dioxide nanoparticles (nano MnO2), health hazards have also emerged. The inflammatory damage of brain tissues could result from nano MnO2, in which the underlying mechanism is still unclear. During this study, we aimed to investigate the role of ROS-mediated p38 MAPK pathway in nano MnO2-induced inflammatory response in BV2 microglial cells. The inflammatory injury model was established by treating BV2 cells with 2.5, 5.0, and 10.0 μg/mL nano MnO2 suspensions for 12 h. Then, the reactive oxygen species (ROS) scavenger (20 nM N-acetylcysteine, NAC) and the p38 MAPK pathway inhibitor (10 μM SB203580) were used to clarify the role of ROS and the p38 MAPK pathway in nano MnO2-induced inflammatory lesions in BV2 cells. The results indicated that nano MnO2 enhanced the expression of pro-inflammatory cytokines IL-1β and TNF-α, elevated intracellular ROS levels and activated the p38 MAPK pathway in BV2 cells. Controlling intracellular ROS levels with NAC inhibited p38 MAPK pathway activation and attenuated the inflammatory response induced by nano MnO2. Furthermore, inhibition of the p38 MAPK pathway with SB203580 led to a decrease in the production of inflammatory factors (IL-1β and TNF-α) in BV2 cells. In summary, nano MnO2 can induce inflammatory damage by increasing intracellular ROS levels and further activating the p38 MAPK pathway in BV2 microglial cells.

Generation of Eroded Nanoplastics from Domestic Wastes and Their Impact on Macrophage Cell Viability and Gene Expression

This study reports an innovative approach for producing nanoplastics (NP) from various types of domestic waste plastics without the use of chemicals. The plastic materials used included water bottles, styrofoam plates, milk bottles, centrifuge tubes, to-go food boxes, and plastic bags, comprising polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE), and Poly (Ethylene-co-Methacrylic Acid) (PEMA). The chemical composition of these plastics was confirmed using Raman and FTIR spectroscopy, and they were found to have irregular shapes. The resulting NP particles ranged from 50 to 400 nm in size and demonstrated relative stability when suspended in water. To assess their impact, the study investigated the effects of these NP particulates on cell viability and the expression of genes involved in inflammation and oxidative stress using a macrophage cell line. The findings revealed that all types of NP reduced cell viability in a concentration-dependent manner. Notably, PS, HDPE, and PP induced significant reductions in cell viability at lower concentrations, compared to PEMA and PET. Moreover, exposure to NP led to differential alterations in the expression of inflammatory genes in the macrophage cell line. Overall, this study presents a viable method for producing NP from waste materials that closely resemble real-world NP. Furthermore, the toxicity studies demonstrated distinct cellular responses based on the composition of the NP, shedding light on the potential environmental and health impacts of these particles.

Acute exposure to polystyrene nanoparticles promotes liver injury by inducing mitochondrial ROS-dependent necroptosis and augmenting macrophage-hepatocyte crosstalk

BACKGROUND

The global use of plastic materials has undergone rapid expansion, resulting in the substantial generation of degraded and synthetic microplastics and nanoplastics (MNPs), which have the potential to impose significant environmental burdens and cause harmful effects on living organisms. Despite this, the detrimental impacts of MNPs exposure towards host cells and tissues have not been thoroughly characterized.

RESULTS

In the present study, we have elucidated a previously unidentified hepatotoxic effect of 20 nm synthetic polystyrene nanoparticles (PSNPs), rather than larger PS beads, by selectively inducing necroptosis in macrophages. Mechanistically, 20 nm PSNPs were rapidly internalized by macrophages and accumulated in the mitochondria, where they disrupted mitochondrial integrity, leading to heightened production of mitochondrial reactive oxygen species (mtROS). This elevated mtROS generation essentially triggered necroptosis in macrophages, resulting in enhanced crosstalk with hepatocytes, ultimately leading to hepatocyte damage. Additionally, it was demonstrated that PSNPs induced necroptosis and promoted acute liver injury in mice. This harmful effect was significantly mitigated by the administration of a necroptosis inhibitor or systemic depletion of macrophages prior to PSNPs injection.

CONCLUSION

Collectively, our study suggests a profound toxicity of environmental PSNP exposure by triggering macrophage necroptosis, which in turn induces hepatotoxicity via intercellular crosstalk between macrophages and hepatocytes in the hepatic microenvironment.

Sublethal effects induced by different plastic nano-sized particles in Daphnia magna at environmentally relevant concentrations

A growing number of studies have reported the toxic effects of nanoplastics (NPs) on organisms. However, the focus of these studies has almost exclusively been on the use of polystyrene (PS) nanospheres. Herein, we aim to evaluate the sublethal effects on Daphnia magna juveniles of three different NP polymers: PS-NPs with an average size of 200 nm, polyethylene [PE] NPs and polyvinyl chloride [PVC] NPs with a size distribution between 50 and 350 nm and a comparable mean size. For each polymer, five environmentally relevant concentrations were tested (from 2.5 to 250 μg/L) for an exposure time of 48 h. NP effects were assessed at the biochemical level by investigating the amount of reactive oxygen species (ROS) and the activity of the antioxidant enzyme catalase (CAT) and at the behavioral level by evaluating the swimming behavior (distance moved). Our results highlight that exposure to PVC-NPs can have sublethal effects on Daphnia magna at the biochemical and behavioral levels. The potential role of particle size on the measured effects cannot be excluded as PVC and PE showed a wider size range distribution than PS, with particles displaying sizes from 50 to 350 nm. However, we infer that the chemical structure of PVC, which differs from that of PE of the same range size, concurs to explain the observed effects. Consequently, as PS seems not to be the most hazardous polymer, we suggest that the use of data on PS toxicity alone can lead to an underestimation of NP hazards.

Determination of the optical interference of iron oxide nanoparticles in fluorometric cytotoxicity assays

Nanomaterials are known to exhibit unique interactions with light. Iron oxide nanoparticles (IONPs), composed of magnetite (black iron oxide) specifically, are known to be highly absorptive throughout the visible portion of the spectrum. We sought to investigate and overcome optical interference of IONPs in colorimetric, fluorometric and luminescence assays by introducing additional controls and determining the concentration-dependent contribution to optical artifacts which could confound, skew, or invalidate results. We tested the in vitro cytotoxicity of ∼8 nm spherical magnetite nanoparticles capped with alginate on a human lung carcinoma (A549) cell line for different exposure periods and at various concentrations. We observed significant interference with both the MTT reagent and the absorption at 590 nm, a concentration-dependent reduction in the luminescence, fluorescence at ∼490 nm (viability marker), and fluorescence at 530 nm (cytotoxicity marker). After introducing an additional correction, we obtained more accurate results, including a clear decrease in viability at 12-h post-treatment, with apparent near complete recovery after 24-h in addition to a dose-independent, time-dependent alteration in the cell proliferation rate. A small increase in cytotoxicity was noted at the 24-h timepoint at the two highest concentrations. According to our results, the MTT reagents appear to interact substantially with IONPs at concentrations above 0.1 mg/mL, therefore, this assay is not recommended for IONP cytotoxicity assessment at higher concentrations.

Combined Effects of Polystyrene Nanosphere and Homosolate Exposures on Estrogenic End Points in MCF-7 Cells and Zebrafish

BACKGROUND

Micro- and nanoplastics (MNPs) and homosalate (HMS) are ubiquitous emerging environmental contaminants detected in human samples. Despite the well-established endocrine-disrupting effects (EDEs) of HMS, the interaction between MNPs and HMS and its impact on HMS-induced EDEs remain unclear.

OBJECTIVES

This study aimed to investigate the influence of MNPs on HMS-induced estrogenic effects and elucidate the underlying mechanisms in vitro and in vivo.

METHODS

We assessed the impact of polystyrene nanospheres (PNSs; 50  nm , 1.0 mg / L ) on HMS-induced MCF-7 cell proliferation (HMS: 0.01 - 1 μ M , equivalent to 2.62 - 262 μ g / L ) using the E-SCREEN assay and explored potential mechanisms through transcriptomics. Adult zebrafish were exposed to HMS (0.0262 - 262 μ g / L ) with or without PNSs (50  nm , 1.0 mg / L ) for 21 d. EDEs were evaluated through gonadal histopathology, fertility tests, steroid hormone synthesis, and gene expression changes in the hypothalamus-pituitary-gonad-liver (HPGL) axis.

RESULTS

Coexposure of HMS and PNSs resulted in higher expression of estrogen receptor α (ESR1) and the mRNAs of target genes (pS2, AREG, and PGR), a greater estrogen-responsive element transactivation activity, and synergistic stimulation on MCF-7 cell proliferation. Knockdown of serum and glucocorticoid-regulated kinase 1 (SGK1) rescued the MCF-7 cell proliferation induced by PNSs alone or in combination with HMS. In zebrafish, coexposure showed higher expression of SGK1 and promoted ovary development but inhibited spermatogenesis. In addition, coexposure led to lower egg hatchability, higher embryonic mortality, and greater larval malformation. Coexposure also modulated steroid hormone synthesis genes (cyp17a2, hsd17[Formula: see text]1, esr2b, vtg1, and vtg2), and resulted in higher 17 β -estradiol (E 2 ) release in females. Conversely, males showed lower testosterone, E 2 , and gene expressions of cyp11a1, cyp11a2, cyp17a1, cyp17a2, and hsd17[Formula: see text]1.

DISCUSSION

PNS exposure exacerbated HMS-induced estrogenic effects via SGK1 up-regulation in MCF-7 cells and disrupting the HPGL axis in zebrafish, with gender-specific patterns. This offers new mechanistic insights and health implications of MNP and contaminant coexposure. https://doi.org/10.1289/EHP13696.

Adsorption and removal of polystyrene nanoplastics from water by green-engineered clays

Human exposure to micro- and nanoplastics (MNPs) commonly occurs through the consumption of contaminated drinking water. Among these, polystyrene (PS) is well-characterized and is one of the most abundant MNPs, accounting for 10 % of total plastics. Previous studies have focused on carbonaceous materials to remove MNPs by filtration, but most of the work has involved microplastics since nanoplastics (NPs) are smaller in size and more difficult to measure and remove. To address this need, green-engineered chlorophyll-amended sodium and calcium montmorillonites (SMCH and CMCH) were tested for their ability to bind and detoxify parent and fluorescently labeled PSNP using in vitro, in silico, and in vivo assays. In vitro dosimetry, isothermal analyses, thermodynamics, and adsorption/desorption kinetic models demonstrated 1) high binding capacities (173-190 g/kg), 2) high affinities (103), and 3) chemisorption as suggested by low desorption (≤42 %) and high Gibbs free energy and enthalpy (>|-20| kJ/mol) in the Langmuir and pseudo-second-order models. Computational dynamics simulations for 30 and 40 monomeric units of PSNP depicted that chlorophyll amendments increased the binding percentage and contributed to the sustained binding. Also, 64 % of PSNP bind to both the head and tail of chlorophyll aggregates, rather than the head or tail only. Fluorescent PSNP at 100 nm and 30 nm that were exposed to Hydra vulgaris showed concentration-dependent toxicity at 20-100 µg/mL. Importantly, the inclusion of 0.05-0.3 % CMCH and SMCH significantly (p ≤ 0.01) and dose-dependently reduced PSNP toxicity in morphological changes and feeding rate. The bioassay validated the in vitro and in silico predictions about adsorption efficacy and mechanisms and suggested that CMCH and SMCH are efficacious binders for PSNP in water.

Environmentally Relevant Concentrations of Microplastic Exposure Cause Cholestasis and Bile Acid Metabolism Dysregulation through a Gut-Liver Loop in Mice

The massive production of plastics causes the ubiquitous existence of microplastics (MPs) in the biota, therefore, posing exposure risks and potential health concerns to human beings. However, the exact mechanisms of MPs-induced toxicities and abnormalities are largely unknown. In this study, we developed a mouse model of gavage polystyrene microplastics (PS MPs) for 30 days. We found that PS MPs can damage the intestinal barrier, accumulate in the liver tissue, and cause injury. The liver and intestine are both highly associated with bile acid (BA) metabolism. Indeed, we found that PS MPs dysregulate BA synthesis and efflux-related gene expression in the liver, causing cholestasis. Tandemly, PS MPs alter the ratio of primary to secondary BA in the feces by affecting the composition of the intestinal flora. At last, PS MPs alter mice's fecal BA profile, which affects normal BA metabolism. Taken together, the present study provides robust data on the mechanism of toxicity of MPs causing the disturbance of BA metabolism via a 4-step gut-liver loop.

Bioenergetic effects of pristine and ultraviolet-weathered polydisperse polyethylene terephthalate and polystyrene nanoplastics on human intestinal Caco-2 cells

The ubiquitous human exposure to nanoplastics (NPs) increasingly raises concerns regarding impact on our health. However, little is known on the biological effects of complex mixtures of weathered NPs with heterogenous size and irregular shape present in the environment. In this study, the bioenergetic effects of four such NPs mixtures on human intestinal Caco-2 cells were investigated. To this aim, Caco-2 cells were exposed to polydisperse nanoPET (<800 nm) and nanoPS (mixture of 100 and 750 nm) samples with and without ultraviolet (UV) weathering at low concentration range (102-107 particles/mL) for 48 h. Mitochondrial respiration, glycolytic functions and ATP production rates of exposed cells were measured by Seahorse XFe96 Analyzer. Among four NPs samples, polydisperse nanoPET with irregular shapes induced significant stimulation of mitochondrial respiration, glycolysis and ATP production rates in Caco-2 cells. Spherical nanoPS caused significant stimulation on glycolytic functions of Caco-2 cells at the highest concentration used (106 particles/mL). ATR-FTIR spectra and carbonyl index indicated formation of carbonyl groups in nanoPET and nanoPS after UV weathering. UV weathering could alleviate bioenergetic stress caused by NPs in Caco-2 cells and even shifted the energy pathways from mitochondrial respiration to glycolysis due to electrostatic repulsion between negatively charged UV-aged NPs and cell membranes. This research is the first to study in-vitro bioenergetic responses of NPs samples with multidimensional features (polymer type, irregular shape, heterogenous size, UV-weathering) on human health. It highlights that effects between pristine and weathered NPs are different at a bioenergetic level, which has important implications for the risk assessment of NPs on human health.

Adsorption-desorption behaviors of ciprofloxacin onto aged polystyrene fragments in aquatic environments

As two emerging pollutants of great concern, microplastics (MPs) and antibiotics inevitably cooccur in various aquatic environments and interact with each other, impacting the fate and ecological risks. Aging obviously complicates their interaction and deserves further study. Therefore, the adsorption-desorption behaviors of ciprofloxacin (CIP) onto polystyrene (PS) fragments with various aging extent were investigated, and the key physiochemical properties influencing the interaction and the interaction mechanisms were clarified by redundancy analysis, FTIR and XPS spectra. The physicochemical properties of PS MPs were significantly changed with aging time, and the morphological and chemical changes seemed to occur asynchronously. The adsorption of CIP onto the pristine PS MPs relied on physisorption, especially the ion-involving electrostatic and cation-π interaction. Due to the hydrogen bonding formed by the C-OH, CO, and O-CO groups of PS and CIP, the adsorption capacities of the aged PS MPs were greatly increased. The desorption efficiency of CIP from MPs in the gastric fluid was closely related to the solution ionic strengths, C-OH and CO groups of MPs, while that in the intestinal fluid was associated with O-CO groups of MPs. The different impact factors could be well described by the differences in the chemical components and pHs of the simulated gastric and intestinal fluids. This study gives a comprehensive understanding of the adsorption-desorption behaviors of antibiotics onto MPs at a molecular level and indicates that MPs could act as Trojan horses to transport antibiotics into aquatic organisms.

Uptake of Nanoplastic particles by zebrafish embryos triggers the macrophage response at early developmental stage

Plastic pollution continues to erupt as a global ecological concern. As plastic debris is degraded into nanoscale and microscale particles via biodegradation, UV-irradiation, and mechanical processes, nanoplastic pollution arises as a threat to virtually every biological and ecological system on the planet. In this study, zebrafish (Danio rerio) embryos were exposed to fluorescently labeled plastic particles at nanoscales (30 nm and 100 nm). The uptake of both the nanoplastic particles (NPs) was found to exponentially increase with incubation time. Penetration of NPs through the natural barrier of the zebrafish embryos, the chorion, was observed prior to the hatching of the embryo. As a result, the NPs were found to accumulate on the body surface as well as inside the body of the zebrafish. The invasion of NPs into zebrafish embryos induced the upregulation of several stress and immune response genes including interleukins (il6 and il1b), cytochrome P450 (cyp1a and cyp51), and reactive oxygen species (ROS) removal protein-encoding genes (sod and cat). This suggested the initiation of ROS generation and removal as well as the activation of the immune response of zebrafish embryos. Colocalization of macrophages and NPs in zebrafish embryos indicated the involvement of macrophage response to the NP invasion at the early developmental stage of zebrafish.

Rethinking the effects of micro/nanoplastics from the global environmental change and systematic perspective: An aquatic environmental system-based comprehensive assessment approach of micro/nanoplastic impacts

The study on micro/nanoplastic pollution should embrace complexity. Here, we aim to develop an aquatic environmental system-based comprehensive assessment approach of micro/nanoplastic impacts (ACAM) to evaluate the effects of micro/nanoplastics on aquatic ecosystems from the global environmental change (GEC) and systematic perspective. A case study for freshwater systems in Saskatchewan, Canada was conducted to evaluate the comprehensive effects of multiple GEC factors (polystyrene-nanoplastics (PS-NPs), N, P, salinity, dissolved organic matter (DOM), pH, hardness) on Asterococcus superbus based on ten ecologically relevant endpoints. It is found that at the cellular level, PS-NPs and N had an antagonistic interaction on microalgal growth in the Saskatchewan freshwater ecosystem; at the molecular level, the PS-NP-induced changes in lipid composition in microalgae were regulated by P, DOM, and pH. The significance ranking of factor effects suggested that instead of PS-NPs pollution, the fluctuations in pH level, DOM and N concentrations should be paid attention to first in Saskatchewan. Under the combined impact of PS-NPs and other GEC factors, microalgae at station 14 (Qu'Appelle River near highway 56) might have the minimum growth rate with [-0.048, 0.094] d-1 in Saskatchewan. These findings demonstrate the efficacy of the developed ACAM in a more comprehensive and context-specific assessment of MNP risks, providing new insight for the management of MNP pollution.

Physiological effects and molecular response in the marine rotifer Brachionus plicatilis after combined exposure to nanoplastics and copper

Because nanoplastics (NPs) can transport pollutants, the absorption of surrounding pollutants into NPs and their effects are important environmental issues. This study shows a combined effect of high concentrations of NPs and copper (Cu) in the marine rotifer Brachionus plicatilis. Co-exposure decreased the growth rate, reproduction, and lifespan. The highest level of NP ingestion was detected in the co-treated group, but the Cu concentration was higher in the Cu single-exposure group. ERK activation played a key role in the downstream cell signaling pathway activated by the interaction of NPs and Cu. The increased sensitivity of B. plicatilis to Cu could be due to the impairment of MXR function caused by a high concentration of NPs, which supports our in vivo experiment results. Our results show that exposure to NPs could induce the dysfunction of several critical molecular responses, weakening resistance to Cu and thereby increasing its physiological toxicity in B. plicatilis.

Characterizing the interaction between micro(nano)plastics and simulated body fluids and their impact on human lung epithelial cells

Micro(nano)plastics are considered an emerging threat to human health because they can interact with biological systems. In fact, these materials have already been found in the human body, such as in the lungs. However, limited data are available on the behavior of these materials under biological conditions and their impact on human cells, specifically on alveolar epithelial cells. In this study, micro(nano)plastics were exposed to various simulated biological fluids (artificial lysosomal fluids and Gamble's solution) for 2-80 h. Pristine and treated plastic particles were characterized based on their surface chemistry, zeta potentials, and elemental composition. Various toxicological endpoints (mitochondrial membrane potential, lactate dehydrogenase, protein, and antioxidant levels) were examined using A549 lung carcinoma cells. The surface characteristics of the treated micro(nano)plastics and the toxicological endpoints of A549 cells were found to be influenced by the simulated biological media, specifically with high concentrations of the treated micro(nano)plastics and increasing exposure under biological conditions. Moreover, the toxicological endpoints were strongly linked to the chemistry of plastics and included multiple processes in response to the plastics; different biological pathways were obtained in artificial lysosomal fluid and Gamble's solution.

Pluronic Induced Interparticle Attraction and Re-entrant Liquid-Liquid Phase Separation in Charged Silica Nanoparticle Suspensions

Tuning surface properties of nanoparticles by introducing charge, surface functionalization, or polymer grafting is central to their stability and applications. Here, we show that introducing non-DLVO forces like steric and hydrophobic effects in charged silica nanoparticle suspensions through interaction with a nonionic surfactant brings about interesting modulations in their interparticle interaction and phase behavior. The Ludox TM-40 negatively charged silica suspensions thus exhibit liquid-liquid phase separation driven by the onset of interparticle attraction in the system in the presence of the triblock copolymer Pluronic P123. The observed phase separations are thermoresponsive in nature, as they are associated with lower consolute temperatures and a re-entrant behavior as a function of temperature. The nanoparticle-Pluronic system thus undergoes transformation from one-phase to two-phase and then back to one-phase with monotonic increase in temperature. Evolution of the interparticle interaction in the composite system is investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), zeta potential, rheological, and fluorescence spectroscopy studies. Zeta potential studies show that the charge interaction in the system is partially mitigated through adsorption of a Pluronic micellar layer on the nanoparticle surfaces. Contrast-matching SANS studies suggest that hydrophobic interactions between the adsorbed micellar layer bring about the onset of interparticle attraction in the system. The results are unique and not reported hitherto in charged silica nanoparticle systems.

Long-Chain Acyl Carnitines Aggravate Polystyrene Nanoplastics-Induced Atherosclerosis by Upregulating MARCO

Exposure to micro- and nanoplastics (MNPs) is common because of their omnipresence in environment. Recent studies have revealed that MNPs may cause atherosclerosis, but the underlying mechanism remains unclear. To address this bottleneck, ApoE^-/- mice are exposed to 2.5-250 mg kg^-1 polystyrene nanoplastics (PS-NPs, 50 nm) by oral gavage with a high-fat diet for 19 weeks. It is found that PS-NPs in blood and aorta of mouse exacerbate the artery stiffness and promote atherosclerotic plaque formation. PS-NPs activate phagocytosis of M1-macrophage in the aorta, manifesting as upregulation of macrophage receptor with collagenous structure (MARCO). Moreover, PS-NPs disrupt lipid metabolism and increase long-chain acyl carnitines (LCACs). LCAC accumulation is attributed to the PS-NP-inhibited hepatic carnitine palmitoyltransferase 2. PS-NPs, as well as LCACs alone, aggravate lipid accumulation via upregulating MARCO in the oxidized low-density lipoprotein-activated foam cells. Finally, synergistic effects of PS-NPs and LCACs on increasing total cholesterol in foam cells are found. Overall, this study indicates that LCACs aggravate PS-NP-induced atherosclerosis by upregulating MARCO. This study offers new insight into the mechanisms underlying MNP-induced cardiovascular toxicity, and highlights the combined effects of MNPs with endogenous metabolites on the cardiovascular system, which warrant further study.

Understanding the aggregation, consumption, distribution and accumulation of nanoparticles of polyvinyl chloride and polymethyl methacrylate in Ruditapes philippinarum

Plastic products have become an integral part of our life. A widespread usage, high stability, uncontrolled disposal and slow degradation of plastics in the environment led to the generation and accumulation of nanoparticles of polymers (NPs) in the marine environment. However, little is known about the aggregation, consumption and distribution of NPs from common polymers such as polyvinyl chloride (NP-PVC) and polymethyl methacrylate (NP-PMMA) inside marine animal physiologies. In the current study, two types of polymers (PVC and PMMA) × four exposure concentrations (1, 5, 15 and 25 mg/L) × four times (4, 8, 12 and 24 h) exposure studies were conducted to understand the consumption and distribution of luminescent NP-PVC (98.6 ± 17.6 nm) and NP-PMMA (111.9 ± 37.1 nm) in R. philippinarum. Under laboratory conditions, NP-PVC showed a higher aggregation rate than NP-PMMA in seawater within a period of 24 h. Aggregations of NPs increased with an increase in initial NP concentrations, leading to significant settling of nanoparticles within 24 h exposure. Such aggregation and settling of particles enhanced the consumption of NPs by benthic filter-feeding R. philippinarum at all exposure concentrations during 4 h exposure. More interestingly, NP-PVC and NP-PMMA were observed in large amounts in both liver and gills (22.6 % - 29.1 %) of the clams. Furthermore, NP-PVC was detected in most organs of R. philippinarum as compared to NP-PMMA. This study demonstrates that different polymers distribute and accumulate differently in the same biological model under laboratory exposure conditions based on their chemical nature.

The Formation of Protein Corona by Nanoplastics and Horseradish Peroxidase

In theory, nanoplastics (NPs) can adsorb biological macromolecules, such as proteins, in the surrounding environment to form protein corona (PC). In this study, we focus on amino polystyrene (PS) NPs and horseradish peroxidase (HRP) to explore the dynamic process of the formation of PS-HRP PC and their influence on PS and HRP. This work used atomic force microscopy, laser particle size and Zeta potential analyzer, and UV-vis spectrophotometer. According to the adsorption behavior of HRP to NPs, the surface morphology characteristics of NPs can be observed to change at 60 min. Meanwhile, the increase in size and hydrodynamic diameter, the decrease in Zeta potential, surface roughness and HRP activity, and the change in HRP structure attest to the PC formation. The thickness of the PC was approximately 30 nm and there are differences in the dynamic and static variations in the size of the PC. The PC formation process progresses gradually from 0 min to 240 min. Overall, the formation of PS-HRP PC is identified, and the changes in its properties are confirmed from the perspective of nanoplastics and peroxidase, which help study the effects of nanoplastics on the environment and creatures.

Surface-Functionalized Polystyrene Nanoparticles Alter the Transmembrane Potential via Ion-Selective Pores Maintaining Global Bilayer Integrity

Although nanoplastics have well-known toxic effects toward the environment and living organisms, their molecular toxicity mechanisms, including the nature of nanoparticle-cell membrane interactions, are still under investigation. Here, we employ dynamic light scattering, quartz crystal microbalance with dissipation monitoring, and electrophysiology to investigate the interaction between polystyrene nanoparticles (PS NPs) and phospholipid membranes. Our results show that PS NPs adsorb onto lipid bilayers creating soft inhomogeneous films that include disordered defects. PS NPs form an integral part of the generated channels so that the surface functionalization and charge of the NP determine the pore conductive properties. The large difference in size between the NP diameter and the lipid bilayer thickness (∼60 vs ∼5 nm) suggests a particular and complex lipid-NP assembly that is able to maintain overall membrane integrity. In view of this, we suggest that NP-induced toxicity in cells could operate in more subtle ways than membrane disintegration, such as inducing lipid reorganization and transmembrane ionic fluxes that disrupt the membrane potential.

Facile nanoplastics formation from macro and microplastics in aqueous media

The immense production of plastic polymers combined with their discordancy with nature has led to vast plastic waste contamination across the geosphere, from the oceans to freshwater reservoirs, wetlands, remote snowpacks, sediments, air and multiple other environments. These environmental pollutants include microplastics (MP), typically defined as small and fragmented plastics less than 5 mm in size, and nanoplastics (NP), particles smaller than a micrometer. The formation of micro and nanoplastics in aqueous media to date has been largely attributed to fragmentation of plastics by natural (i.e., abrasion, photolysis, biotic) or industrial processes. We present a novel method to create small microplastics (≲ 5 μm) and nanoplastics in water from a wide variety of plastic materials using a small volume of a solubilizer liquid, such as n-dodecane, in combination with vigorous mixing. When the suspensions or solutions are subjected to ultrasonic mixing, the particle sizes decrease. Small micro- and nanoparticles were made from commercial, real world and waste (aged) polyethylene, polystyrene, polycarbonate and polyethylene terephthalate, in addition to other plastic materials and were analyzed using dark field microscopy, Raman spectroscopy and particle size measurements. The presented method provides a new and simple way to create specific size distributions of micro- and nanoparticles, which will enable expanded research on these plastic particles in water, especially those made from real world and aged plastics. The ease of NP and small MP formation upon initial mixing simulates real world environments, thereby providing further insight into the behavior of plastics in natural settings.

Threats to Terrestrial Plants from Emerging Nanoplastics

Nanoplastics are ubiquitous in ecosystems and impact planetary health. However, our current understanding on the impacts of nanoplastics upon terrestrial plants is fragmented. The lack of systematic approaches to evaluating these impacts limits our ability to generalize from existing studies and perpetuates regulatory barriers. Here, we undertook a meta-analysis to quantify the overall strength of nanoplastic impacts upon terrestrial plants and developed a machine learning approach to predict adverse impacts and identify contributing features. We show that adverse impacts are primarily associated with toxicity metrics, followed by plant species, nanoplastic mass concentration and size, and exposure time and medium. These results highlight that the threats of nanoplastics depend on a diversity of reactions across molecular to ecosystem scales. These reactions are rooted in both the spatial and functional complexities of nanoplastics and, as such, are specific to both the plastic characteristics and environmental conditions. These findings demonstrate the utility of interrogating the diversity of toxicity data in the literature to update both risk assessments and evidence-based policy actions.

The effects of nanoplastics on adipose stromal cells from swine tissues

Plastic is one of the main sources of marine and terrestrial pollution. This material can fragment into micro- (<-5 mm) and nanoplastics (NPs) (<100 nm) following degradation. Animals are exposed to these particles by ingesting contaminated food, respiration or filtration, and transdermally. In organisms, NPs can cross biological membranes, and cause oxidative stress, cell damage, apoptosis, and endocrine interference. We previously demonstrated that polystyrene - NPs interfered with ovarian cell functions. Since reproduction involves a high energy expenditure and a crucial role is played by adipose tissue, the aim of the present study was to evaluate the effects of NPs on primary adipose stromal cells (ASCs) isolated from swine adipose tissues. In particular, the effects on cell viability, proliferation, metabolic activity, inflammatory process mediators and oxidative stress markers were assessed. The obtained results did not reveal a significant variation in cell proliferation, metabolic activity was increased (P < 0.01) but only at the lowest concentration, while viability showed a significant decrease after prolonged exposure to NPs (P < 0.01). TNF-α was increased (P < 0.05), while PAI-1 was inhibited (P < 0.001). Redox status was significantly modified; in particular, the production of O₂^-_, H₂O₂ and NO was stimulated (P < 0.05), the non-enzymatic antioxidant power was reduced (P < 0.05) while catalase activity was significantly (P < 0.01) increased.

Advances in bioremediation of emerging contaminants from industrial wastewater by oxidoreductase enzymes

The bioremediation of emerging recalcitrant pollutants in wastewater via enzyme biotechnology has been evolving as cost-effective with an input of low-energy technological approach. However, the enzyme based bioremediation technology is still not fully developed at a commercial level. The oxidoreductases being the domineering biocatalysts are promising candidates for wastewater treatments. Henceforth, comprehending their global market and biotransformation efficacy is mandatory for establishing these techno-economic bio-enzymes in commercial scale. The biocatalytic strategy can be established as a combinatorial approach with existing treatment technology to achieve towering bioremediation and effective removal of emerging pollutants from wastewater. This review provides a novel insight on the toxicological xenobiotics released from industries such as paper and pulps, soap and detergents, pharmaceuticals, textiles, pesticides, explosives and aptitude of peroxidases, nitroreductase and cellobiose dehydrogenase in their bio-based treatment. Moreover, the review comprehensively covers environmental relevance of wastewater pollution and the critical challenges based on remediation achieved through biocatalysts for future prospectives.

Exposure to nanoplastic induces cell damage and nitrogen inhibition of activated sludge: Evidence from bacterial individuals and groups

Wastewater treatment plants (WWTPs) are almost the only place where plastic fragments are artificially removed, resulting in mass accumulation of nanoplastics (NPs). In this research, four different concentrations (0 mg/L, 0.1 mg/L, 1 mg/L, 10 mg/L) of polystyrene nanoplastics (PS-NPs) were used to investigate the cell damage and nitrogen inhibition of activated sludge, exposed in a self-assembled SBR reactor for 30 days. Intracellular reactive oxides (ROS) and extracellular lactate dehydrogenase (LDH) increased with the rise of exposure concentration, and morphological analysis disclosed the creases, collapse, and even rupture of cell membranes. However, exposure damage (PS-NPs ≤ 1 mg/L) appeared to be reversible, attributed to that extracellular polymeric substances (EPS) secretion can thicken the three protective layers outside the membrane. PS-NPs did not disrupt the EPS chemical structure, but increased humic acid content. Prolonged exposure time (from 15 to 30 days) was directly related to the nitrogen inhibition. Due to the habitat changes under PS-NPs exposure, abundance and diversity of microorganisms in the original activated sludge decreased significantly, and the dominant phylum was occupied by Patescibacteria (PS-NPs = 10 mg/L). Changes in enzyme activities of AMO, NR, NIR, and NOR with exposure concentration may explain the conversion of nitrogen in SBR. This research broadens our horizons to understand the response mechanism of activated sludge bacteria to PS-NPs exposure individually and collectively.

Development of Photoluminescent ZnO Nanoparticles for Biological Tracking

Nanoparticles (NPs) that can be optically tracked are of interest for cell and organismal biodistribution studies. However, dyes or fluorophores crosslinked or adsorbed onto NP surfaces may detach or leach, resulting in optical artifacts. NP surfaces altered to carry dyes or fluorophores are also anticipated to affect toxicity profiles, protein interactions, and cell uptake. Zinc oxide (ZnO) NPs provide a potential solution. We have produced ZnO nanoparticles with different morphologies and defect emissions in the visible range using sol-gel chemistry. Several of the nanocomposites produced have a wide visible band emission. ZnO semiconductor nanocomposites have broad applications in many fields. They may be dispersed in polymers, functionalized for cell targeting, conjugated to drugs or proteins. We report a unique 600 nm emission peak, which is of interest for nano-bio interaction studies currently limited by autofluorescence in biologicals and the spectral overlap of common fluorescent dyes and proteins.

Amino-Functionalized Polystyrene Nano-Plastics Induce Mitochondria Damage in Human Umbilical Vein Endothelial Cells

As emerging contaminants, nano-plastics have become a major cause for concern for their adverse effects on the ecosystem and human health. The nano-sized properties of nano-plastics enable their exposure risks to humans through the food chain or other ways. However, the fate and adverse impact of nano-plastics on the human cardiovascular system are lacking. In this regard, the human umbilical vein endothelial cell line HUVEC was applied as a cell model to investigate the biological effects of noncharged polystyrene nano-plastics (PS NPs) and amino-functionalized nano-plastics (NH₂-PS NPs). The positively charged PS NPs exhibited higher cytotoxicity to HUVEC, as evidenced by the decreased cell viability, enhanced ROS generation, and decreased mitochondria membrane potential triggered by NH₂-PS NPs. Importantly, RT-PCR analysis revealed that NH₂-PS NPs dysregulated the mitochondrial dynamics, replication, and function-related gene expression. This study demonstrated that NH₂-PS NPs presented higher risks to endothelial cells than non-charged nano-plastics by interfering with mitochondria, which supported the direct evidence and expanded the potential risks of PS NPs.

Co-Exposure of Nanopolystyrene and Other Environmental Contaminants-Their Toxic Effects on the Survival and Reproduction of Enchytraeus crypticus

Plastics in all shapes and sizes have become widespread across ecosystems due to intense anthropogenic use. As such, they can interact with other contaminants that accumulate in the terrestrial environment, such as pharmaceuticals, metals or nanomaterials (NMs). These interactions can potentiate combined toxic effects in the exposed soil organisms, with hazardous long-term consequences to the full ecosystem. In the present study, a terrestrial model species, Enchytraeus crypticus (oligochaeta), was exposed through contaminated soil with nanopolystyrene (representative of nanoplastics (NPls)), alone and in combination with diphenhydramine (DPH, representative of pharmaceuticals), silver nitrate (AgNO₃, representative of metals) and vanadium nanoparticles (VNPs, representative of NMs). AgNO₃ and VNPs decreased E. crypticus reproduction at 50 mg/kg, regardless of the presence of NPls. Moreover, at the same concentration, both single and combined VNP exposures decreased the E. crypticus survival. On the other hand, DPH and NPls individually caused no effect on organisms' survival and reproduction. However, the combination of DPH (10 and 50 mg/kg) with 300 mg NPls/kg induced a decrease in reproduction, showing a relevant interaction between the two contaminants (synergism). Our findings indicate that the NPls can play a role as vectors for other contaminants and can potentiate the effects of pharmaceuticals, such as DPH, even at low and sub-lethal concentrations, highlighting the negative impact of mixtures of contaminants (including NPls) on soil systems.