Researchers have tried hard to study the toxic effects of single pollutants like certain antibiotics and nanoplastic particles on plants. But we still know little about how these pollutants interact when they're together in the environment, and what combined toxic effects they have on plants. This study assessed the toxic effects of polystyrene nanoplastics (PS-NPs) and ciprofloxacin (CIP), both individually and in combination, on soybean (Glycine max L.) seedlings by various concentration gradients treatments of PS-NPs (0, 10, 100 mg/L) and CIP (0, 10 mg/L). The results indicated that high concentrations of PS-NPs significantly impeded soybean seedling growth, as evidenced by reductions in root length, plant height, and leaf area. CIP predominantly affected the physiological functions of leaves, resulting in a decrease in chlorophyll content. The combined exposure demonstrated synergistic effects, further intensifying the adverse impacts on the growth and physiological functions of soybean seedlings. Metabolomic analyses indicated that single and combined exposures markedly altered the metabolite expression profiles in soybean leaves, particularly related to amino acid and antioxidant defense metabolic pathways. These results indicate the comprehensive effects of NPs with antibiotics on plants and provide novel insights into toxic mechanisms.

Nanoplastics (NPs) and zinc (Zn), both widespread in soil environments, present considerable risks to soil biota. While NPs persist environmentally and act as vectors for heavy metals like Zn, their combined toxicity, especially in soil invertebrates, remains poorly understood. This study evaluates the individual and combined effects of Zn and NPs on earthworm coelomocytes and explores their interactions with Cu/Zn-superoxide dismutase (SOD), an antioxidant enzyme. Molecular docking revealed that NPs bind near the active site of SOD through pi-cation interactions with lysine residues, further stabilized by neighboring hydrophobic amino acids. Viability assays indicated that NPs alone (20 mg/L) had negligible impact (94.54 %, p > 0.05), Zn alone (300 mg/L) reduced viability to 80.02 %, while co-exposure reduced it further to 73.16 %. Elevated levels of reactive oxygen species (ROS) and malondialdehyde (MDA) levels were elevated to 186 % and 173 % under co-exposure, alongside greater antioxidant enzyme disruption, point to synergistic toxicity. Dynamic light scattering and zeta potential (From -13 to -7 mV) analyses revealed larger particle sizes in the combined system, indicative of enhanced protein interactions. Conformational changes in SOD, such as alpha-helix loss and altered fluorescence, further support structural disruption. These findings demonstrate that co-exposure to NPs and Zn intensifies cellular and protein-level toxicity via integrated physical and biochemical mechanisms, providing critical insight into the ecological risks posed by such co-contaminants in soil environments.

Investigating the toxicological effects of aged nanoplastics (NPs) in soil is critical, as UV irradiation may exacerbate their ecological toxicity by altering surface properties and enhancing interactions with the soil. Here, we investigated the effects of different concentrations of pristine and aged polystyrene (PS) and carboxylpolystyrene (PSC) NPs on lettuce and soil properties. Both pristine and aged NPs inhibited pigment synthesis and lettuce growth. The maximum growth inhibition rates of leaf (root) biomass were 10.2 % (23.4 %) and 32.7 % (45.3 %) for pristine PS and PSC (50 mg center dot L- 1) and 26.7 % (35.9 %) and 43.1 % (57.8 %) for aged PS and PSC (50 mg center dot L- 1), respectively. NPs induced excessive reactive oxygen species (ROS) production in the leaves and roots, antioxidant defense mechanisms, and oxidative damage, which was more pronounced with aged NPs. ROS accumulation gradually increased with aging time and concentration of NPs, which inhibited photosynthesis and decreased biomass. At the same aging duration, exposure to either pristine or aged NPs significantly reduced soil pH. Compared to the control, neither pristine nor aged NPs altered the composition of dissolved organic matter, whereas aged PSC induced a significant increase in the intensity of soluble microbial byproducts; this was attributed to differences in soil acidity and alkalinity. Low concentrations of pristine and aged NPs increased the Chao 1 index in soils, exhibiting hormesis, and altered relative microbial abundances. Pristine and aged PS/ PSCs promoted microbial oxidative phosphorylation, carbon fixation pathways in prokaryotes, and the tricarboxylic acid cycle. The results provide critical insights into the impacts of NPs on plant and soil microbial growth.

Micro- and nanoplastics (MNPs), pervasive environmental pollutants, contaminate water, soil, air, and the food chain and ultimately accumulate in living organisms. Macrophages are the main immune cells that gather around MNPs and engulf them through the process of phagocytosis. This internalization triggers M1 polarization and the secretion of inflammatory cytokines, including IL-1, IL-18, IL-12, TNF-alpha, and IFN-gamma. Furthermore, MNPs damage mitochondria and lysosomes, causing overactivation of iNOS and excessive production of ROS. This results in cellular stress and induce apoptosis, necroptosis, and, in some cases, metosis in macrophages. The internalization of MNPs also increases the expression of receptors, involving CD36, SR-A, LOX-1, and the macrophage receptor with a collagenous structure (MARCO) while decreasing ABCA-1 and ABCG-1. MNPs in adipose tissue macrophages trigger proinflammatory cytokine secretion, causing adipogenesis, lipid accumulation, insulin resistance, and the secretion of inflammatory cytokines in adipocytes. Various factors influence the rate of MNP internalization by macrophages, including size, charge, and concentration, which affect internalization through passive diffusion. Receptor-mediated phagocytosis of MNPs occurs directly via receptors like T-cell immunoglobulin and mucin domain containing 4 (TIM-4) and MARCO. The attachment of biomolecules, including proteins, antibodies, opsonins, or microbes to MNPs (forming corona structures) promotes indirect receptor-mediated endocytosis, as macrophages possess receptors like TLRs and Fc gamma RIII. MNPs also cause gut dysbiosis, a risk factor for proinflammatory microenvironment and M1 polarization. Here, we review the mechanisms and consequences of MNP macrophage exposure, which is linked to autoimmunity, inflammation, and cardiometabolic syndrome manifestations, including atherosclerosis and obesity, highlighting the immunotoxicity of MNPs.

Typically, nanoplastics (NPs) are contaminated before entering soil, and the impact of NPs on the biotoxicity of Persistent Organic Pollutants (POPs) they carry remains unclear. This study simulated two environmentally relevant scenarios: singular exposure of benzo[a]pyrene (BaP) in soil and exposure via NPs loading (NP-BaP). Correlation analysis and machine learning revealed that injury in earthworms exposed for 28 days was significantly associated with NPs. Moreover, when the soil exposure concentration of BaP was 4 mg/kg, the NP-BaP group exhibited 10.67 % greater pigmentation than the BaP-only group. Despite the lower biota soil accumulation factor (BSAF) of earthworms in the NP-BaP group, the concentration of BaP in the soil remained at higher levels in the late stages of exposure. This led to NP-BaP inducing a stronger trend of oxidative damage compared to BaP alone. Furthermore, molecular-level studies indicated that the differential preferences of NPs and BaP for damaging antioxidant enzymes were linked to individual oxidative stress responses. This study confirmed that NPs, at non-toxic concentrations, could increase the persistence of BaP's biological toxicity after prolonged exposure, highlighting the potential safety risks of NPs as carriers of POPs to soil organisms.

This study explored morphological, physiological, molecular, and epigenetic responses of tomatoes (Solanum lycopersicum) to soil contamination with polyethylene nanoplastics (PENP; 0.01, 0.1, and 1 gkg-1 soil). The PENP pollution led to severe changes in plant morphogenesis. The PENP treatments were associated with decreased plant biomass, reduced internode length, delayed flowering, and prolonged fruit ripening. Abnormal inflorescences, flowers, and fruits observed in the PENP-exposed seedlings support genetic changes and meristem dysfunction. Exposure of seedlings to PENP increased H2O2 accumulation and damaged membranes, implying oxidative stress. The PENP treatments induced activities of catalase (EC1.11.1.6), peroxidase (EC1.11.1.7), and phenylalanine ammonia-lyase (EC4.3.1.24) enzymes. Soil contamination with PENP also decreased the net photosynthesis, maximum photosystem efficiency, stomatal conductance, and transpiration rate. The nanopollutant upregulated the expression of the histone deacetylase (HDA3) gene and R2R3MYB transcription factor. However, the AP2a gene was down-regulated in response to the PENP treatment. Besides, EPNP epigenetically contributed to changes in DNA methylation. The concentrations of proline, soluble phenols, and flavonoids also displayed an upward trend in response to the applied PENP treatments. The long-term exposure of seedlings to PENP influenced fruit biomass, firmness, ascorbate, lycopene, and flavonoid content. These findings raise concerns about the hazardous aspects of PENP to agricultural ecosystems and food security.

BackgroundAs modern industrial activities have advanced, the prevalence of microplastics and nanoplastics in the environment has increased, thereby impacting plant growth. Potassium is one of the most crucial nutrient cations for plant biology. Understanding how polyethylene terephthalate (PET) treatment affects potassium uptake will deepen our understanding of plant response mechanisms to plastic pollution.ResultsIn this study, we examined the impact of PET micro- and nanoplastics on foxtail millet seedling growth and potassium accumulation. Additionally, we measured reactive oxygen species (ROS) production, antioxidant enzyme activities, and the expression levels of the corresponding enzyme-encoding genes. Our findings indicated that the germination and seedling growth of foxtail millet were not significantly affected by exposure to PET plastics. However, the ROS levels in foxtail millet increased under these conditions. This increase in ROS led to the upregulation of several genes involved in K+ uptake and transport (SiHAK1, SiHAK2, SiAKT2/3, SiHKT2;2, SiHKT1;1, SiGORK, and SiSKOR), thereby increasing K+ accumulation in foxtail millet leaves. Further research revealed that higher K+ concentrations in plant leaves were correlated with increased expression of the antioxidant-related genes SiCAT1, SiPOD1, and SiSOD3, as well as increased activities of the corresponding antioxidant enzymes. This response helps mitigate the excessive accumulation and damage caused by ROS in plant cells after PET nanoplastic treatment, suggesting a potential stress response mechanism in foxtail millet against nanoplastic pollution.ConclusionsOur research indicates that PET nanoplastic treatment induces the expression of genes related to K+ uptake in foxtail millet through ROS signaling, leading to increased K+ accumulation in the leaves. This process mitigates the ROS damage caused by PET nanoplastic treatment by increasing the expression and activity of genes encoding antioxidant enzymes. The present research has unveiled the K+ accumulation-related response mechanism of foxtail millet to PET nanoplastic treatment, contributing significantly to our understanding of both the potassium absorption regulation mechanism in plants and the broader impact of plastic pollution on agricultural crops. This discovery not only highlights the complexity of plant responses to environmental stressors but also underscores the importance of considering such responses when evaluating the ecological and agricultural implications of plastic pollution.

Soil microbiomes drive many soil processes and maintain the ecological functions of terrestrial ecosystems. Microplastics (MPs, size <5 mm) are pervasive emerging contaminants worldwide. However, how MPs affect soil microbial activity has not been well elucidated. This review article first highlights the effects of MPs on overall soil microbial activities represented by three soil enzymes, i.e., catalase, dehydrogenase, and fluorescein diacetate hydrolase (FDAse), and explores the underlying mechanisms and influencing factors. Abundant evidence confirms that MPs can change soil microbial activities. However, existing results vary greatly from inhibition to promotion and non-significance, depending on polymer type, degradability, dose, size, shape, additive, and aging degree of the target MPs, soil physicochemical and biological properties, and exposure conditions, such as exposure time, temperature, and agricultural practices (e.g., planting, fertilization, soil amendment, and pesticide application). MPs can directly affect microbial activities by acting as carbon sources, releasing additives and pollutants, and shaping microbial communities via plastisphere effects. Smaller MPs (e.g., nanoplastics, 1 to <1000 nm) can also damage microbial cells through penetration. Indirectly, MPs can change soil attributes, fertility, the toxicity of co-existing pollutants, and the performance of soil fauna and plants, thus regulating soil microbiomes and their activities. In conclusion, MPs can regulate soil microbial activities and consequently pose cascading consequences for ecosystem functioning.

Micro/nano-plastics (M/NPs) are pervasive in agricultural soils, and their detrimental effects on crops are increasingly evident. This ultimately results in reduced crop yields and quality, posing a great threat to global food security. Therefore, the urgent need to mitigate the phytotoxicity of M/NPs has become apparent. Biochar (BC), as an environmentally friendly soil amendment, plays a crucial role in modifying soil properties and boosting agricultural production levels. Its strong adsorption capacity enables it to effectively passivate soil pollutants and reduce their phytotoxicity. However, the effect of BC on the phytotoxicity of M/NPs in soil remains unknown. In this study, the feasibility of BC amendment for mitigating phytotoxicity of polyvinyl chloride M/NPs (PVC-M/NPs) was evaluated by conducting pot experiments. The results show that the application of 0.1% (w/w) PVC-M/NPs resulted in a 48.60% reduction in lettuce yield. This reduction can be attributed to the decreased soil microbial activity and soil cation exchange capacity (CEC), as well as the direct physical damage to lettuce roots caused by PVC-M/NPs. BC amendment improved soil quality, but had insignificant effect on lettuce biomass compared to the control (p > 0.05). In contrast, BC amendment at an appropriate concentration (0.5% and 2.5%, w/w) to soils contaminated with PVC-M/NPs resulted in a significant increase in lettuce yield (p < 0.01). Furthermore, BC was found to mitigate the oxidative stress of PVC-M/NPs on lettuce roots. This indicates that the BC amendment has the potential to mitigate the toxicity of PVC-M/NPs to lettuce. Improving soil quality and enhancing PVC-M/NPs adsorption are perceived as the influencing mechanisms of BC on the phytotoxicity of PVC-M/NPs. The findings suggest that it is feasible to mitigate the phytotoxicity of M/NPs through BC amendments.

Excessive nanoplastics not only pose a direct threat to the environment but also have the propensity to adsorb and interact with other pollutants, exacerbating their impact. The coexistence of nanoplastics and heavy metals in soils is a prevalent phenomenon. However, limited research existed about the joint effects of the two contaminants on soil organisms. In this paper, we ascertained the combined toxicity of polystyrene nanoplastics (PSNPs) and copper (Cu2+) on soil organisms (Caenorhabditis elegans) at quantities that were present in the environment, further exploring whether the two toxicants were synergistic or antagonistic. The outcomes manifested that single exposure to low-dose PS-NPs (1 mu g/L) would not cause significant damage to nematodes. After treatment with PS-NPs and Cu2+, the locomotion ability of nematode was impaired, accompanied by an elevation in reactive oxygen species (ROS) level and a biphasic response in antioxidant enzyme activity. Moreover, combined exposure to PS-NPs and Cu2+ induced the mRNA up-regulation of vit-6, cyp-35a2, hsp-16.2, age-1, and cep-1, both of which were stress-related genes. The comparative analysis between groups (with or without PSNPs) revealed that the combined exposure group resulted in significantly greater toxic effects on nematodes compared with Cu2+ exposure alone. Furthermore, the addition of PS-NPs influenced the metabolic profiles of Caenorhabditis elegans under Cu2+ stress, with numerous differential metabolites associated with oxidative damage or defense mechanism. Overall, these findings manifested that PS-NPs at the expected environmental concentration elevated Cu2+ toxicity on nematodes.