Size-classifiable quantification of nanoplastic by rate zonal centrifugation coupled with pyrolysis-gas chromatography-mass spectrometry.

Particle size is an important indicator to evaluate the environmental risk and biotoxicity of nanoplastic (NP, particle diameter <1000 nm). The methods available to determine size classes of NP in environmental samples are few and are rare to achieve efficient separation and recycling of NP with close particle sizes. Here, we show that rate-zonal centrifugation (RZC) can quickly and efficiently collect NP of different sizes based on their sedimentation coefficients. When combined with cloud-point extraction (CPE) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), our method can quantify three NP particle-size classes separately (including 100 nm, 300 nm, and 600 nm) in aqueous samples with high recovery (81.4 %-89.4 %), limits of detections (LODs, 33.5-53.4 µg/L), and limits of quantifications (LOQs, 110.6-167.2 µg/L). Compared with the conventional sample pretreatment process, our method can effectively extract and determine the NP with different sizes. Our approach is highly scalable and can be effectively applied to NP in a wide range of aquatic environments. Meanwhile, our approach is highly scalable to incorporate diverse assays to study the environmental behaviours and ecological risks of NP.

Efficient degradation of sulfonamides by introducing sulfur to magnetic Prussian blue analog in photo-assisted persulfate oxidation system.

The peroxynitrite photocatalytic degradation system was considered a green, convenient, and efficient water treatment process, but not satisfying against some antibiotics, e.g. sulfonamides (SAs). To improve the photocatalytic degradation efficiency of SAs, sulfur was introduced to a magnetic Fe-MOF (Fe-metal organic framework) Prussian blue analog to achieve a heteroatomic material CuFeO@S, which was applied in heterogeneous visible light photo-assisted catalytic process with persulfate (PS) as an oxidant. The characterization results of CuFeO@S by XRD and XPS confirmed the presence of Fe3O4 (for magnetic separation), Cu+ (for activation of PS) and S2- (for narrowing the energy band and prolonging the lifetime of photo-generated electronics). Through systematic optimization of reaction conditions in CuFeO@S + PS + hv system, efficient degradation of four tested SAs was achieved in 30 min (removal rate of 97-100% for the tested 4 SAs). Moreover, the material could be magnetically recycled and reused for over 7 cycles with a removal rate of >90% for sulfamerazine. Furthermore, the removal rate of sulfamerazine in pond water reached 99% at a mineralization rate of about 34% (decrease in total organic matter), demonstrating its potential in the treatment of antibiotic-containing wastewater.

Quantification and Characterization of Fine Plastic Particles as Considerable Components in Atmospheric Fine Particles.

The negative effects of air pollution, especially fine particulate matter (PM2.5, particles with an aerodynamic diameter of ≤2.5 µm), on human health, climate, and ecosystems are causing significant concern. Nevertheless, little is known about the contributions of emerging pollutants such as plastic particles to PM2.5 due to the lack of continuous measurements and characterization methods for atmospheric plastic particles. Here, we investigated the levels of fine plastic particles (FPPs) in PM2.5 collected in urban Shanghai at a 2 h resolution by using a novel versatile aerosol concentration enrichment system that concentrates ambient aerosols up to 10-fold. The FPPs were analyzed offline using the combination of spectroscopic and microscopic techniques that distinguished FPPs from other carbon-containing particles. The average FPP concentrations of 5.6 µg/m3 were observed, and the ratio of FPPs to PM2.5 was 13.2% in this study. The FPP sources were closely related to anthropogenic activities, which pose a potential threat to ecosystems and human health. Given the dramatic increase in plastic production over the past 70 years, this study calls for better quantification and control of FPP pollution in the atmosphere.

A proteomic study on gastric impairment in rats caused by microcystin-LR.

Microcystins (MCs) are the most common cyanobacterial toxins. Epidemiological investigation showed that exposure to MCs can cause gastro-intestinal symptoms, gastroenteritis and gastric cancer. MCs can also accumulate in and cause histopathological damage to stomach. However, the exact mechanisms by which MCs cause gastric injury were unclear. In this study, Wistar rats were administrated 50, 75 or 100 µg microcystin-LR (MC-LR)/kg, body mass (bm) via tail vein, and histopathology, response of anti-oxidant system and the proteome of gastric tissues at 24 h after exposure were studied. Bleeding of fore-stomach and gastric corpus, inflammation and necrosis in gastric corpus and exfoliation of mucosal epithelial cells in gastric antrum were observed following acute MC-LR exposure. Compared with controls, activities of superoxide dismutase (SOD) were significantly greater in gastric tissues of exposed rats, while activities of catalase (CAT) were less in rats administrated 50 µg MC-LR/kg, bm, and concentrations of glutathione (GSH) and malondialdehyde (MDA) were greater in rats administrated 75 or 100 µg MC-LR/kg, bm. These results indicated that MC-LR could disrupt the anti-oxidant system and cause oxidative stress. The proteomic results revealed that MC-LR could affect expressions of proteins related to cytoskeleton, immune system, gastric functions, and some signaling pathways, including platelet activation, complement and coagulation cascades, and ferroptosis. Quantitative real-time PCR (qRT-PCR) analysis showed that transcriptions of genes for ferroptosis and gastric function were altered, which confirmed results of proteomics. Overall, this study illustrated that MC-LR could induce gastric dysfunction, and ferroptosis might be involved in MC-LR-induced gastric injury. This study provided novel insights into mechanisms of digestive diseases induced by MCs.

Colorimetric Detection of Multiple Phenols Based on Multifunctional Fe3 O4 /SnS2 Composites.

Phenols pose a great threat to human and environment due to their high toxicity and low bio-degradability. Therefore, the development of a rapid and sensitive detection method for multiple phenols is of great importance. Here, a colorimetric detection method based on Fe3 O4 /SnS2 composites was established for the detection and discrimination of ten phenols for the first time. The results demonstrated that the incorporation of the photo catalyst SnS2 significantly improved the peroxidase-like activity of Fe3 O4 , leading to an enhancing efficiency of the colorimetric detection method. The developed method was capable of detecting phenol within a concentration range of 0.5-2000 µM, with detection limit as low as 0.06 µM. This method was successfully applied to detect total phenols in samples obtained from two sewage treatment plants and seawater. Furthermore, by employing principal component analysis, the established colorimetric method enabled the simultaneous discrimination of all ten phenols. The performance was further evaluated by accurately identifying binary or ternary mixtures of phenols, and even identifying the type of phenol in 10 unknown samples containing one of the ten phenols. These findings highlight the potential of the Fe3 O4 /SnS2 composite as a promising candidate for the simultaneous detection of multiple phenols in liquid samples.

Rapid screening of benzyl dodecyl dimethyl ammonium bromide co-metabolic degrading bacteria based on NIR hyperspectral imaging technology.

As a typical disinfectant, the use of benzyl dodecyl dimethyl ammonium bromide (BDAB) has dramatically increased since the emergence of SARS-CoV-2, posing a threat to environmental balance and human health. Screening BDAB co-metabolic degrading bacteria is required for efficient microbial degradation. Conventional methods for screening co-metabolic degrading bacteria are laborious and time-consuming, especially when the number of strains is large. This study aimed to develop a novel method for the rapid screening of BDAB co-metabolic degrading bacteria from the cultured solid medium using near-infrared hyperspectral imaging (NIR-HSI) technology. Based on NIR spectra, the concentration of BDAB in the solid medium can be well predicted by partial least squares regression (PLSR) models, non-destructively and rapidly, with Rc2 > 0.872 and Rcv2 > 0.870. The results show that the predicted BDAB concentrations decrease after degrading bacteria utilization, comparing with the regions where no degrading bacteria grew. The proposed method was applied to directly identify the BDAB co-metabolic degrading bacteria cultured on the solid medium, and two kinds of co-metabolic degrading bacteria RQR-1 and BDAB-1 were correctly identified. This method provides a high-efficiency method for screening BDAB co-metabolic degrading bacteria from a large number of bacteria.

From Medical Herb to Functional Food: Development of a Fermented Milk Containing Silybin and Protein from Milk Thistle.

Milk thistle is a traditional medicinal herb. Silybin is a medicinal component found in the seed coat of milk thistle, which has liver-protective and anti-cancer properties. Conventional studies have focused on the extraction of silybin with organic reagents, which was inapplicable to the food industry. This study aims to develop a fermented milk containing silybin and protein from the milk thistle seeds. A three step procedure was developed, comprising homogenization of milk thistle seeds, NaHCO3 heat treatment, and microbial fermentation. The silybin was characterized by high performance liquid chromatography, and the protein was quantified and electrophorized. It was found that the homogenization step was essential for the preparation of protein, and the NaHCO3 heat treatment was the crucial step in obtaining silybin. The optimal NaHCO3 treatment settings were 1% NaHCO3, 60°C, and 3 h, and the optimal strains for microbial fermentation were L131 (Rummeliibacillus stabekisii) and RS72 (Lactobacillus plantarum). The silybin yield in the fermented milk reached 11.24-12.14 mg/g seeds, accounting for 72.6-78.4% of the total silybin in the milk thistle seeds, and the protein yield reached 121.8-129.6 mg/g seeds. The fermented milk had a slightly sweet yoghurt-like flavor and could be used as a dietary supplement for silybin and protein.

Non-Destructive Extraction and Separation of Nano- and Microplastics from Environmental Samples by Density Gradient Ultracentrifugation.

Nano-/microplastics (NMPs, particle diameter < 5 mm) are widespread emerging pollutants causing diverse impacts on organisms due to their sizes, shapes, and chemical properties. Despite the fast increase in NMP research, an effective method to separate and identify NMP types from environmental samples is still lacking. Here, we developed a simple and effective approach for the non-destructive extraction and separation of various types of NMPs from environmental samples by density gradient ultracentrifugation (DGU). For the first time, DGU was capable to separate various NMPs from the complex matrix with high selectivity (100%), purity (93%), and applicability. Through a gradually changing density of the density gradient medium by changing the concentrations or volumes of CsCl/water solution (from 0.00065 to 0.01989 g cm-3 mm-1), various NMPs (with particle sizes as little as 50 nm) could be extracted and separated from soil samples with high recovery (78.5-96.0%). We confirmed the effectiveness and compatibility of DGU through a correct identification of all types of NMPs separated from artificial soil samples with Raman spectroscopy, simultaneous thermal analysis (STA), and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). DGU is compatible with all analytical processes compared to other existing methods with much less sample pretreatment time (0.5 h). Overall, DGU is an effective and cheap method (2.2 USD/sample) to separate NMPs from environmental samples such as soil and water and, hence, can facilitate research on NMPs related to terrestrial and marine environments as well as human health.

Identification and characterization of Fe3O4/peroxodisulfate advanced oxidation products from sulfameter.

Sulfonamides (SAs) are one of the most widely used antibiotics and their residuals in the environment could cause some negative environmental issues. Advanced oxidation such as Fenton-like reaction has been widely applied in the treatment of SAs polluted water. Degradation rates of 95%-99.7% were achieved in this work for the tested 8 SAs, including sulfisomidine, sulfameter (SME), phthalylsulfathiazole, sulfamethoxypyridazine, sulfamonomethoxine, sulfisoxazole, sulfachloropyridazine, and sulfadimethoxine, in the Fe3O4/peroxodisulfate (PDS) oxidation system after the optimization of PDS concentration and pH. Meanwhile, it was found that a lot of unknown oxidation products were formed, which brought up the uncertainty of health risks to the environment, and the identification of these unknown products was critical. Therefore, SME was selected as the model compound, from which the oxidation products were never elucidated, to identify these intermediates/products. With liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS), 10 new products were identified, in which 2-amino-5-methoxypyrimidine (AMP) was confirmed by its standard. The investigation of the oxidation process of SME indicated that most of the products were not stable and the degradation pathways were very complicated as multiple reactions, such as oxidation of the amino group, SO2 extrusion, and potential cross-reaction occurred simultaneously. Though most of the products were not verified due to the lack of standards, our results could be helpful in the evaluation of the treatment performance of SAs containing wastewater.

C/N-Dependent Element Bioconversion Efficiency and Antimicrobial Protein Expression in Food Waste Treatment by Black Soldier Fly Larvae.

The black soldier fly (BSF), Hermetia illucens, has emerged as a promising species for waste bioconversion and source of antimicrobial proteins (AMPs). However, there is a scarcity of research on the element transformation efficiency and molecular characterization of AMPs derived from waste management. Here, food waste treatment was performed using BSF larvae (BSFL) in a C/N ratio of 21:1−10:1, with a focus on the C/N-dependent element bioconversion, AMP antimicrobial activity, and transcriptome profiling. The C-larvae transformation rates were found to be similar among C/Ns (27.0−35.5%, p = 0.109), while the N-larvae rates were different (p = 0.001), with C/N 21:1−16:1 (63.5−75.0%) being higher than C/N 14:1−10:1 (35.0−45.7%). The C/N ratio did not alter the antimicrobial spectrum of AMPs, but did affect the activities, with C/N 21:1 being significantly lower than C/N 18:1−10:1. The lysozyme genes were found to be significantly more highly expressed than the cecropin, defensin, and attacin genes in the AMP gene family. Out of 51 lysozyme genes, C/N 18:1 and C/N 16:1 up-regulated (p < 0.05) 14 and 12 genes compared with C/N 21:1, respectively, corresponding to the higher activity of AMPs. Overall, the element bioconversion efficiency and AMP expression can be enhanced through C/N ratio manipulation, and the C/N-dependent transcriptome regulation is the driving force of the AMP difference.