Polymer chain extenders induce significant toxicity through DAF-16 and SKN-1 pathways in Caenorhabditis elegans: A comparative analysis.

Polymer chain extenders, commonly used in plastic production, have garnered increasing attention due to their potential environmental impacts. However, a comprehensive understanding of their ecological risks remains largely unknown. In this study, we employed the model organism Caenorhabditis elegans to investigate toxicological profiles of ten commonly-used chain extenders. Exposure to environmentally relevant concentrations of these chain extenders (ranging from 0.1 µg L-1 to 10 mg L-1) caused significant variations in toxicity. Lethality assays demonstrated the LC50 values ranged from 92.42 µg L-1 to 1553.65 mg L-1, indicating marked differences in acute toxicity. Sublethal exposures could inhibit nematodes' growth, shorten lifespan, and induce locomotor deficits, neuronal damage, and reproductive toxicity. Molecular analyses further elucidated the involvement of the DAF-16 and SKN-1 signaling pathways, as evidenced by upregulated expression of genes including ctl-1,2,3, sod-3, gcs-1, and gst-4. It implicates these pathways in mediating oxidative stress and toxicities induced by chain extenders. Particularly, hexamethylene diisocyanate and diallyl maleate exhibited markedly high toxicity among the chain extenders, as revealed through a comparative analysis of multiple endpoints. These findings demonstrate the potential ecotoxicological risks of polymer chain extenders, and suggest the need for more rigorous environmental safety assessments.

Algae polysaccharide-induced transport transformation of nanoplastics in seawater-saturated porous media.

This study examined the distinct effects of algae polysaccharides (AP), namely sodium alginate (SA), fucoidan (FU), and laminarin (LA), on the aggregation of nanoplastics (NP) in seawater, as well as their subsequent transport in seawater-saturated sea sand. The pristine 50 nm NP tended to form large aggregates, with an average size of approximately 934.5 ± 11 nm. Recovery of NP from the effluent (Meff) was low, at only 18.2 %, and a ripening effect was observed in the breakthrough curve (BTC). Upon the addition of SA, which contains carboxyl groups, the zeta (ζ)-potential of the NP increased by 2.8 mV. This modest enhancement of electrostatic interaction with NP colloids led to a reduction in the aggregation size of NP to 598.0 ± 27 nm and effectively mitigated the ripening effect observed in the BTC. Furthermore, SA's adherence to the sand surface and the resulting increase in electrostatic repulsion, caused a rise in Meff to 27.5 %. In contrast, the introduction of FU, which contains sulfate ester groups, resulted in a surge in ζ-potential of the NP to -27.7 ± 0.76 mV. The intensified electrostatic repulsion between NP and between NP and sand greatly increased Meff to 45.6 %. Unlike the effects of SA and FU, the addition of LA, a neutral compound, caused a near disappearance of ζ-potential of NP (-3.25 ± 0.68 mV). This change enhanced the steric hindrance effect, resulting in complete stabilization of particles and a blocking effect in the BTC of NP. Quantum chemical simulations supported the significant changes in the electrostatic potential of NP colloids induced by SA, FU and LA. In summary, the presence of AP can induce variability in the mobility of NP in seawater-saturated porous media, depending on the nature of the weak, strong, or non-electrostatic interactions between colloids, which are influenced by the structure and functionalization of the polysaccharides themselves. These findings provide valuable insights into the complex and variable behavior of NP transport in the marine environment.

Soil-dwelling grub larvae of Protaetia brevitarsis biodegrade polystyrene: Responses of gut microbiome and host metabolism.

Plastic pollution poses a significant threat to terrestrial ecosystems, yet the potential for soil fauna to contribute to plastic biodegradation remains largely unexplored. In this study, we reveal that soil-dwelling grubs, Protaetia brevitarsis larvae, can effectively biodegrade polystyrene (PS) plastics. Over a period of 4 weeks, these grubs achieved a remarkable 61.5 % reduction in PS foam mass. This biodegradation was confirmed by the depolymerization of ingested PS, formation of oxidative functional groups, noticeable chemical modifications, and an increase of δ13C of residual PS in frass. Additionally, antibiotic treatment to suppress gut microbes led to variations in the biodegradation process. PS ingestion induced a significant shift in the gut microbiome, promoting the growth of degradation-related bacteria such as Promicromonosporaceae, Bacillaceae, and Paenibacillaceae. Furthermore, the digestion of plastic triggered extensive metabolomic reprogramming of grubs' intestines, enhancing redox capabilities and facilitating PS biodegradation. These results indicate that responsive adaptation of both the gut microbiome and the host's intestinal metabolism contributes to PS degradation. Collectively, these findings demonstrate P. brevitarsis larvae's capability to alleviate soil plastic pollution, and highlight the potential of researching soil fauna further for sustainable plastic waste management solutions.

Removal of microplastics from water by coagulation of cationic-modified starch: An environmentally friendly solution.

Microplastics (MPs) pose a potential risk to aquatic ecosystems, and there is a growing demand to alleviate the contamination of MPs. Here, we introduce cationic-modified starch (CS) as an eco-friendly bio-coagulant for removing MPs from water. CS with varying degrees of substitution was synthesized and characterized, and its performance in removing MPs was evaluated under different MP sizes, types, and aging, as well as various water conditions. The results indicated that CS efficiently removed MPs, achieving an average removal rate of 65.33 % for polystyrene particles, with higher removal rates for larger, high-density, and aged MPs. The efficiency of CS remained consistent across a wide range of water pH values, but was significantly reduced in the presence of kaolin clay or/and humic acid. The removal efficiency of CS for MPs was enhanced by the non-ionic surfactant, Tween 20, but inhibited by the anionic surfactant, cetyltrimethylammonium bromide. In addition, CS could concurrently remove both MPs and phenanthrene, as a typical water contaminant. Moreover, the applicability of CS was demonstrated in natural water samples from the Ecological Demonstration Zone of the Yangtze River Delta, China, with an average removal rate of 60.13 ± 3.15 %. Taken together, this study offers an environmentally friendly and cost-effective approach for the removal of MPs from water, demonstrating CS has significant application potential as a sustainable solution to mitigate microplastic pollution.

DNA origami-mediated plasmonic dimer nanoantenna-based SERS biosensor for ultrasensitive determination of trace diethylstilbestrol.

Diethylstilbestrol (DES) is a threatening factor to the human endocrine system. Here, we reported a DNA origami-assembled plasmonic dimer nanoantenna-based surface-enhanced Raman scattering (SERS) biosensor for measuring trace DES in foods. A critical factor influencing the SERS effect is interparticle gap modulation of SERS hotspots with nanometer-scale accuracy. DNA origami technology aims to generate naturally perfect structures with nano-scale precision. Exploiting the specificity of base-pairing and spatial addressability of DNA origami to form plasmonic dimer nanoantenna, the designed SERS biosensor generated electromagnetic-enhancement and uniform-enhancement hotspots to improve sensitivity and uniformity. Owing to their high target-binding affinity, aptamer-functionalized DNA origami biosensors transduced the target recognition into dynamic structural transformations of plasmonic nanoantennas, which were further converted to amplified Raman outputs. A broad linear range from 10-10 to 10-5 M was obtained with the detection limit of 0.217 nM. Our findings demonstrate the utility of aptamer-integrated DNA origami-based biosensors as a promising approach for trace analysis of environmental hazards.

Polystyrene nanospheres-induced hepatotoxicity in swamp eel (Monopterus albus): From biochemical, pathological and transcriptomic perspectives.

As ubiquitous emerging pollutants, microplastics (MPs) in aquatic environments have aroused critical global concerns. Despite the occurrence and characteristics of MPs in freshwater agroecosystems well-described by our previous study, their ecotoxicological implications in Monopterus albus remains unfathomed. Herein, we dissected toxic effects and mechanisms of PS-NPs exposure against M. albus hepatic tissues at concentrations of 0.5 (L), 5 (M), 10 (H) mg/L for 28 days using physiochemical measurements, histopathological analysis and transcriptomic sequencing. Results showed that upon PS-NPs treatments, levels of ROS, MDA, 8-OHdG and MFO activity were significantly enhanced relative to the control (C) group, while SP content and T-AOC activity were dramatically suppressed, suggesting ROS burst, lipid peroxidation and DNA damage may occur in liver tissues. This oxidative damage further triggered impaired hepatic function and histopathology, disordered lipid metabolism and hepatocyte apoptosis, as reflected by significantly diminished activities of GPT, GOT, ACP, AKP and LDH, paralleled with augmented levels of TG, TC and HSI as well as Cytc and Caspase-3,8,9 activities. Noticeably, concentration-dependent rises of apoptotic rate, vacuolar degeneration and lipid deposition were manifest in TUNEL, H&E and ORO staining. In addition, a total of 375/475/981 up-regulated as well as 260/611/1422 down-regulated DEGs in C vs L, C vs M and C vs H categories were identified based on RNA-seq, respectively. These DEGs were significantly annotated and enriched into GO terms (membrane, cytoplasm, response to stimuli, oxidation-reduction process) as well as KEGG pathways (ether lipid metabolism, apoptosis, chemical carcinogenesis-reactive oxygen species, non-alcoholic fatty liver disease). Moreover, signaling cascades Keap1-Nrf2, p53 and PPAR were either substantially initiated or dysregulated to orchestrate PS-NPs hepatotoxicity featuring oxidative damage, hepatocyte apoptosis and lipid steatosis. Collectively, this study not only expounded on toxicological mechanisms whereby PS-MPs exerted deleterious effects on M. albus, but also pointed to ecological risks of PS-MPs-induced hepatoxicity and lipid steatosis in this commercially-important species.

Prominent toxicity of isocyanates and maleic anhydrides to Caenorhabditis elegans: Multilevel assay for typical organic additives of biodegradable plastics.

Biodegradable plastics (BDP) are increasingly applied; however, there has been of concerns about their environmental safety, especially from nondegradable additive compositions. Until now, data of ecotoxicity of BDP additives is scarce. Here, nematode C. elegans was used to comparatively evaluate toxicity of an isocyanate additive, i.e., Hexamethylene diisocyanate (HDI), a maleic anhydride, i.e., Diallyl maleate (DIM), and other four BDP organic additives. These additives caused lethality of nematodes at µg L-1 level, of lowest LC50 value of HDI/DIM. Uniform exposure to these additives resulted in various degrees of inhibitions in body volumes and longevity, indicating developmental toxicity. Moreover, BDP additives induced significant elevations of gst-4 expression, especially mean 123.54 %/234.29 % increase in HDI/DIM group, but reduced ges-1 expression, which indicates oxidative damages and mitochondrial dysfunction. BDP additives further caused inhibition in locomotor and food intake/excretion behavior, and related damages of glutamatergic neurons and GABAergic neurons, indicating their neurotoxicity. We found HDI and DIM presented relatively strong effects on susceptible endpoints including lethality, gst-4, mean lifespan, food intake and excretion behavior. Overall, this study suggests prominent ecotoxic risk of isocyanates and maleic anhydrides as BDP additives, which is significant for the selection of environmentally friendly BDP additives.

Nanoplastics induce molecular toxicity in earthworm: Integrated multi-omics, morphological, and intestinal microorganism analyses.

The toxicity of nanoplastics (NPs) at relatively low concentrations to soil fauna at different organismal levels is poorly understood. We investigated the responses of earthworm (Eisenia fetida) to polystyrene NPs (90-110 nm) contaminated soil at a relatively low concentration (0.02 % w:w) based on multi-omics, morphological, and intestinal microorganism analyses. Results showed that NPs accumulated in earthworms' intestinal tissues. The NPs damaged earthworms' digestive and immune systems based on injuries of the intestinal epithelium and chloragogenous tissues (tissue level) and increased the number of changed genes in the digestive and immune systems (transcriptome level). The NPs reduced gut microorganisms' diversity (Shannon index) and species richness (Chao 1 index). Proteomic, transcriptome, and histopathological analyses showed that earthworms suffered from oxidative and inflammatory stresses. Moreover, NPs influenced the osmoregulatory metabolism of earthworms as NPs damaged intestinal epithelium (tissue level), increased aldosterone-regulated sodium reabsorption (transcriptome level), inositol phosphate metabolism (proteomic level) and 2-hexyl-5-ethyl-furan-3-sulfonic acid, and decreased betaine and myo-inositol concentrations (metabolic level). Transcriptional-metabolic and transcriptional-proteomic analyses revealed that NPs disrupted earthworm carbohydrate and arachidonic acid metabolisms. Our multi-level investigation indicates that NPs at a relatively low concentration induced toxicity to earthworms and suggests that NPs pollution has significant environmental toxicity risks for soil fauna.

Microfiber-loaded bacterial community in indoor fallout and air-conditioner filter dust.

Microfibers (MFs) are widely existed in indoor air; however, characteristic of microbiota on MFs is largely unknown. In this study, air-borne MFs were collected from fallout or air-conditioner (AC) filter dust in three types of indoor space including living room, dormitory and office. Both plastic and natural MFs were identified by Fourier transform infrared spectroscopy. Ultramicroscopic observation showed dense biofilms adhering on surfaces of MFs. Fallout MFs contained more bacteria but fewer fungi than MFs from AC filter dust. MFs-loaded bacteria were of highest abundance in living rooms, following dormitories and offices. Bacterial community and its diversity were further analyzed by 16S rRNA High-throughput sequencing. Up to 4540 of bacterium OTUs were shared in these MFs samples, unique OTUs in fallout and AC filter samples accounting for 26.3 % and 25.7 % of the total. Compared to MFs fallout, AC filter MFs contained more species of pathogenic bacteria, such as Betaproteobacteriales and Ralstonia, with obviously different ß-diversity between two groups. Phenotypic analysis showed that fallout and AC filter MFs bacteria presented high index values of film formation, oxidative stress tolerance and potential pathogenicity. Overall, these results suggest that abundant bacteria including pathogen can be loaded on MFs, and would pose health risks through delivery of indoor MFs.

Degradation of polylactic acid/polybutylene adipate films in different ratios and the response of bacterial community in soil environments.

Biodegradable plastic mulch film (BDM) is an environmentally friendly alternative to conventional polyethylene mulch, and has been growingly used in agriculture. However, practical degradation performance of BDM, especially the widely used type of blended polylactic acid (PLA)/polybutylene adipate (PBAT) in different ratios, and microbial alteration in soil environments, remain largely unrevealed. In this study, four types of BDM blended with 40-80% PLA and 20-60% PBAT were comparatively investigated through microcosm soil incubation experiments for 105 days, and combined with conditions of different soil moisture or pH. Microbiome within film-surrounding soil were assayed using 16 S rRNA high-throughput sequencing. Results showed a trend of increasing degradation efficiency with the increase of PLA proportion, and 70% PLA and 30% PBAT group presented the highest weight loss rate, i.e., 60.16 ± 5.86%. In addition, degradation and aging of PLA/PBAT varied among different soil moisture and pH values. A moderate moisture, i.e., 60% and a neutral pH7.0 caused significantly high degradation efficiency compared to other moisture or pH conditions. Moreover, bacterial abundance and community structure in the surrounding soil were related to soil moisture and pH. PLA/PBAT incubation treatment induced a remarkable increase in abundance of degradation-related species Pseudomonas and Sphingomonas. Bacterial richness and diversity in soil correspondingly respond to ratio-different PLA/PBAT's degradation under moisture/pH-different conditions through a redundancy analysis. Altogether, these findings indicate that practical degradation of PLA/PBAT film is closely related to soil environments and bacterial community. It is significant for the application of biodegradable plastics in agriculture on the perspective of soil sustainability.

Magnetic Halloysite Nanotube-Based SERS Biosensor Enhanced with Au@Ag Core-Shell Nanotags for Bisphenol A Determination.

Bisphenol A (BPA) has emerged as a contaminant of concern because long-term exposure may affect the human endocrine system. Herein, a novel aptamer sensor based on magnetic separation and surface-enhanced Raman scattering (SERS) is proposed for the extremely sensitive and specific detection of trace BPA. Moreover, the capture unit was prepared by immobilizing thiolated (SH)-BPA aptamer complementary DNA on AuNP-coated magnetic halloysite nanotubes (MNTs@AuNPs), and SH-BPA aptamer-modified Au@4-MBA@Ag core-shell SERS nanotags acted as signal units. By the complementary pairing of the BPA aptamer and the corresponding DNA, MNTs@AuNPs and Au@4-MBA@AgCS were linked together through hybridization-ligation, which acted as the SERS substrate. In the absence of BPA, the constructed aptamer sensor generated electromagnetic enhancement and plasmon coupling to improve the sensitivity of SERS substrates. Owing to the high affinity between BPA and the aptamer, the aptamer probe bound to BPA was separated from the capture unit by an externally-induced magnetic field. Thus, the Raman intensity of the MNTs@AuNP-Ag@AuCS core-satellite assemblies was negatively correlated with the BPA concentration. High sensitivity measurements of BPA might be performed by determining the decline in SERS signal strength together with concentration variations. The proposed aptasensor is a promising biosensing platform for BPA detection.

A battery of baseline toxicity bioassays directed evaluation of plastic leachates-Towards the establishment of bioanalytical monitoring tools for plastics.

There are increasing concerns regarding the ecological risks of plastics to the natural environment, especially the potential effects of plastic leachates on organisms, which contain various toxic components. However, appropriate methods to assess the overall environmental risks of plastics are limited. In this study, five different plastic products (three conventional and two biodegradable plastics) were immersed in simulated freshwater, and their toxicity was assessed using a battery of bioassays. We evaluated the effects of plastic leachates effects on organisms from four trophic levels of species (nematodes, Caenorhabditis elegans; algae, Scenedesmus obliquus; daphnids, Daphnia magna; and fish, Danio rerio) by measuring their acute and chronic toxicity. Our results indicated that all plastic leachates exhibited poor acute and chronic toxicity to the organisms. The acute toxicity of conventional plastic leachates with EC20 values <1.6 g plastic/L was higher than that of the biodegradable polydioxanone (PPDO) leachate (EC20: 16.2-796.1 g plastic/L); however, the toxicity of PPDO-octane (EC20: 0.04-1.9 g plastic/L) was similar to that of polyethylene or polystyrene (excluding toxicity in D. magna). Similarly, the leachates of the three conventional plastics and PPDO-octane had obvious inhibitory effects on the growth of C. elegans at exposure concentrations higher than 0.01 g plastic/L; however, the toxicity of the PPDO leachates was at least an order of magnitude lower. Therefore, the environmental related concentration of the plastic leachates did not have significant toxic effects. Considering that a single bioassay does not provide comprehensive information on biological implications, this study provided a new integrated and efficient method for the environmental risk assessment (ERA) of plastic leachates. Moreover, the toxicity sensitivity of different organisms varied following exposure to different plastics, thus demonstrating that multiple organisms from different trophic levels should be included in the ERA for plastics.

Size/shape-dependent migration of microplastics in agricultural soil under simulative and natural rainfall.

Agricultural soil is a sink of microplastics (MPs) in the environment. MPs in topsoil can be transferred deeply or into surrounding water by rainfall. However, little is known about rainfall-induced migration pattern of different MPs in agricultural soil. In this study, soil leaching experiments of 21 d were performed on Nile red-stained size-different polyethylene terephthalate (PET) particles, and shape-different polyethylene (PE) MPs under simulated or natural rainfall. Results showed that simulated rainfall of 5-25 mm/d caused intensity-dependent migration of MPs in horizontal and vertical directions. Maximum migration depth of MP particles arrived up to 4-7 cm. Rise of soil slopes could significantly increase horizontal mobility of MPs. Comparatively, natural rainfall of similar intensity caused relatively high mobility of MPs. Moreover, under both simulative and natural rainfall, mobility of MPs presented size/shape-different characteristics. Comparatively, small-size MPs (especially <1 mm) showed relatively high mobility in horizontal or vertical direction, and had high-frequency presence in runoff water. Of four MPs' shapes, fiber and film had relatively high mobility in comparison to particles. These results indicate that rainfall can cause size/shape-dependent migration of MPs in agricultural soil. It suggests size/shape-different environment fate of MPs, and provides a reference for MP control.

National-scale distribution of micro(meso)plastics in farmland soils across China: Implications for environmental impacts.

Microplastics (MPs) pollution is increasingly appreciated as a significant environmental issue, however, the large-scale pattern of MPs in farmland soils and its associated environmental impacts are unknown. This study investigated a national-scale distribution of micro(meso)plastics (MMPs) in the soil of 30 farmlands across China. The abundance of MMPs in soils was 25.56-2067.78 items kg-1, with a mean of 358.37 items kg-1, i.e. 6.79 mg kg-1 or 0.0007% after mass conversion. MPs accounted for 93.1% of MMPs, the abundance varied greatly among different regions, high in arid or semi-arid north but relatively low in mild southwest regions. Major MPs included polypropylene, polyethylene, and polyester, tending to decrease in abundance from surface to deeper soil layers. Further, meta-analysis revealed that MPs exposure influenced bulk density, soil enzymes including fluorescein diacetate hydrolase (FDAse) and urease, and crop biomass, and minimum effective concentrations (MEC) were in the range of 0.0040-10%. We found that actual abundance in the national-scale soils was lower than MEC, but partly overlapped or close, which implies various degrees of environmental impacts. These findings disclose the national-scale pollution pattern of MPs in farmlands and its latent risks to soil environments and crop growth.

Air conditioner filters become sinks and sources of indoor microplastics fibers.

Indoor airborne microplastics fibers (MPFs) are emerging contaminants of growing concern. Nowadays, air conditioners (ACs) are widely used in indoor environments. However, little is known about their impact on the distribution of indoor MPFs. In this study, we first disclosed the prevalence of MPF contamination in filters for indoor split ACs used in living rooms, dormitories, and offices. The average density of microfibers was 1.47-21.4 × 102 items/cm2, and a total 27.7-35.0% of fibers were MPFs. Of these fibers, the majority were polyester (45.3%), rayon (27.8%), and cellophane (20.1%). We further tracked the long-term accumulation of MPFs on AC filters in three types of rooms, and demonstrated that dormitories showed relatively heavy accumulation especially after running for 35-42 days. Furthermore, we found that simulative AC filters which had been lined with PET MPFs could effectively release those MPFs into indoor air, propelling them away from the ACs at varying distances. Statistical analysis showed that the estimated daily intake of MPFs (5-5000 µm length) from AC filters would increase gradually with their usage, with the intake volume reaching up to 11.2 ± 2.2-44.0 ± 8.9 items/kg-BW/day by the 70th day, although this number varied among people of different ages. Altogether, these findings suggest that AC filters can act as both a sink and a source of microplastics fibers. Therefore, AC filters should be evaluated not only for their substantial impact on the distribution of indoor airborne MPFs, but also for their role in the prevalence of the related health risks.

Removal of microplastics from water by magnetic nano-Fe3O4.

Microplastics (MPs) have been widely detected in aquatic environments, and become emerging contaminants of growing concern. It is urgently needed to explore how to effectively remove MPs from water. This study first established an alternative method of removing MPs by magnetic nano-Fe3O4. Results showed that 1.3 g·L-1 nano-Fe3O4 and 150 min treatments caused optimal magnetization of MPs via surface absorption. Then, magnetized MPs in water can be conveniently removed by suction of the magnet. The average removal rate of four common types of MPs including polyethylene, polypropylene, polystyrene and polyethylene terephthalate in size of approximately 200-900 µm was 86.87 ± 6.92%, 85.05 ± 4.70%, 86.11 ± 6.21%, and 62.83 ± 8.34%, respectively. The removal rate varied among polymer- and size-different MPs, and was positively related to the density of nano-Fe3O4 absorbed on MP surfaces. In addition, the removal rate of MPs in artificial seawater was relatively high in comparison to pure water. Furthermore, the established approach was effectively applied to remove MPs in environmental water bodies including river water, domestic sewage, and natural seawater, with the removal rate of higher than 80%. Altogether, this study provided a novel and simple removal approach to remove MPs in water, which has a certain application prospect.

Surface-enhanced Raman spectroscopy aptasensor for simultaneous determination of ochratoxin A and zearalenone using Au@Ag core-shell nanoparticles and gold nanorods.

The design and fabrication of a surface-enhanced Raman scattering (SERS) aptasensor for simultaneous detection of zearalenone (ZEN) and ochratoxin A (OTA) in wheat and corn samples is described. The capture and reporter probes were SH-cDNA-modified gold nanorods and SH-Apt-modified Au@Ag core-shell nanoparticles, respectively. After recognizing OTA and ZEN aptamers and complementary strands (SH-cDNA), the reporter probe generated a strong SERS signal. The preferred binding of OTA and ZEN aptamers to OTA and ZEN, respectively, caused reporter probes to release the capture probes, resulting in a linear decrease in SERS intensity. The detection of OTA showed good linearity with an R2 value of 0.986, which could be maintained across a wide concentration range (0.01 to 100 ng/mL), with the limit of detection of 0.018 ng/mL. For detection of ZEN, good linearity with an R2 value of 0.987 could be maintained across a wide concentration range (0.05 to 500 ng/mL), with 0.054 ng/mL as the limit of detection. Good accuracy (relative standard deviation < 4.2%) during mycotoxin determination as well as excellent quantitative recoveries (96.0-110.7%) during the analysis of spiked real samples was achieved. The proposed SERS aptasensor exhibited excellent performance in the detection of OTA and ZEN in real food samples. Hence, by simply changing the aptamer, this new model can be applied to the detection of multiple mycotoxins in the food industry.

Methods for separating microplastics from complex solid matrices: Comparative analysis.

Microplastics (MPs) are widely found in complex solid matrices such as soil, sediments and sludge. The separation procedure is crucial for effective analysis of MPs, but existing methods varied among studies. Here, we systematically summarize and compare separation methods including density, oil, electrostatic, magnetic, and solvent extraction separation. Density separation is the most commonly used approach, but time-consuming and discharging hazardous materials dependent on extraction solutions. In contrast, oil, electrostatic, magnetic separation and solvent extraction separation are emerging approaches with advantages of low-cost, quick, or environmentally-friendly, but with high request of instruments. Despite variation among these approaches, the separation efficiency is closely related to characteristics of MPs including polymer types, sizes and shapes. The treatment of digestion and fluorescence staining can facilitate the detection of MPs. This analysis suggests that further optimization and improvement of existing approaches can facilitate the development of new separation technology for assaying MPs in complex environmental matrices.

Biodegradation and disintegration of expanded polystyrene by land snails Achatina fulica.

Despite increasing evidence of widespread plastic pollution in soil, it remains largely unknown about the fate of plastic influenced by soil animals. In this study, ingestion and biodegradation capability of expanded polystyrene (PS) foam was investigated in a globally distributed soil invertebrate, Achatina fulica. After 4-week exposure, 18.5 ± 2.9 mg polystyrene was ingested per snail, and egested microplastics (1.343 ± 0.625 mm) in feces with significant mass loss of mean 30.7%. Gel permeation chromatography analysis indicated a significant increase in weight-average molecular weight (Mw) and number-average molecular weight (Mn) of feces-residual PS, indicating limited extent depolymerization. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance confirmed the formation of functional groups of oxidized intermediates. Suppression of gut microbes with oxytetracycline did not affect the depolymerization, indicating the independence of gut microbes. High-throughput sequencing analysis revealed significant shifts in the gut microbiome after ingestion of PS, with an increase of family Enterobacteriaceae, Sphingobacteriaceae, and Aeromonadaceae, suggesting that gut microorganisms were associated with PS biodegradation. These findings suggest that plastic litter can be disintegrated into microplastics and partially biodegraded by A. fulica, which highlights the significance of soil animals for the fate of plastic and its biodegradation in soil environments.

Size-dependent cellular internalization and effects of polystyrene microplastics in microalgae P. helgolandica var. tsingtaoensis and S. quadricauda.

Microplastics (MPs) are persistent contaminants in aquatic environments. Microalgae, as the main phytoplankton and primary producers, usually co-exist with MPs. Despite previous studies that have proved the interaction of MPs and microalgae, it is largely unknown whether MPs can be uptake into cells of microalgae. In this study, both marine P. helgolandica var. tsingtaoensis and freshwater microalgae S. quadricauda were respectively exposed to 10 mg/L polystyrene microbeads with five diameter sizes: 1.0, 2.0, 3.0, 4.0, and 5.0 µm. Confocal laser scanning and 3D image analysis showed that mean 24.0 % or 11.3 % cells of P. helgolandica var. tsingtaoensis contained 1.0 µm or 2.0 µm MPs after 72 h exposure. While mean 43.3 % or 15.3 % of S. quadricauda individuals engulfed 1.0 µm or 2.0 µm MPs within cells. But, none of 3.0-5.0 µm MPs were observed within algal cells. These results demonstrate the size-dependent cellular internalization of MPs in microalgae. Exposure to 1.0-2.0 µm PS MPs caused a significant reduction in the density of microalgae and influenced photosynthesis, which suggests cellular internalization of MPs can influence algal fertility and growth. This discovery first confirms cellular internalization of MPs in phytoplankton, of significance for the fate and eco-toxicity of MPs in the aquatic ecosystem.