The fate, acute, and subchronic risks of dinotefuran in the water-sediment system: A systematic analysis at the enantiomer level.

Environmental risks associated with neonicotinoid insecticides have attracted considerable attention. This study systematically investigated the stereoselective behavior of dinotefuran in a water-sediment system. The results showed that S-dinotefuran accumulated more easily in sediment and zebrafish. Although dinotefuran enantiomers and metabolites present a low risk to aquatic organisms, the risk of dinotefuran enantiomers to sediment organisms should be considered. Additionally, S-dinotefuran induced more remarkable oxidative damage in zebrafish than that of R-dinotefuran. Nevertheless, R-dinotefuran remarkably activated antioxidant and detoxifying enzymes. Multi-omics analyses revealed that S-dinotefuran induced more differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) in zebrafish. In particular, S-dinotefuran inhibited the expression of ribosome- and proteasome-related genes and proteins, affecting the synthesis and degradation of proteins in zebrafish. R-dinotefuran remarkably activated peroxisome-related genes and proteins, thereby enhancing antioxidant and detoxification abilities of zebrafish. The stereoselective interactions between dinotefuran enantiomers and key DEPs were elucidated using AlphaFold2 modeling and molecular docking techniques, which may serve as the main reason for stereoselective subchronic toxicity. The present study is beneficial for the correct use of dinotefuran and provides an effective means for elucidating the mechanism of the stereoselective behavior of chiral compounds.

Systematic evaluation of chiral fungicide penflufen for the bioactivity improvement and input reduction using alphafold2 models and transcriptome sequencing.

Traditional risk assessment of pesticide concludes at the racemic level, which is often incomprehensive. In this study, systematic studies on environmental stability, bioactivity, and ecotoxicological effects of fungicide penflufen were carried out at the enantiomeric level. The single-enantiomer of penflufen was successfully separated and prepared, and their stability was verified in different environmental matrices. Meanwhile, bioactivity test indicated that S-(+)-penflufen had increased bioactivity with its bioactivities against Rhizoctonia solani, Fusarium oxysporum, and Fusarium moniliforme being factors of 7.8, 1.8, and 4.7, respectively greater than those of R-(-)-penflufen. Molecular docking results showed the strong hydrogen bond interactions with Leu300, enantiomer-specific hydrophobic interactions with Cys299, Arg91, and His93, and the greater binding energy between S-(+)-penflufen and succinate dehydrogenase of Rhizoctonia solani caused the selective bioactivity. Additionally, two enantiomers showed low acute toxicity whereas selective sub-chronic toxicity to earthworms. In sub-chronic toxicity test, the accumulated enantiomers caused abnormalities in intestinal tract structure, enzyme activities, and gene expression of earthworms, especially in the S-(+)-penflufen treatment. The selective interactions between penflufen enantiomers and key proteins were elucidated using molecular docking, which may be the main reason of stereoselective subchronic toxicity. S-(+)-penflufen has high bioactivity and low acute risk, it has great potential for development.

Kelp-derived N-doped biochar activated peroxymonosulfate for ofloxacin degradation.

N-doped carbon materials have been proven to be effective catalysts for activating peroxymonosulfate (PMS). Marine algae biomass is rich in nitrogenous substances , which can reduce the cost of N-doping process and can obtain excellent N-doped catalysts cheaply and easily. In this study, kelp biomass was selected to prepare N-doped kelp biochar (KB) materials. The high defect degree, high specific surface area, and participation of graphite N make KB have excellent catalytic degradation ability. The KB degraded 40 mg/L ofloxacin (OFL) close to 100% within 60 min, applied with PMS. Through quenching experiments and electron paramagnetic resonance spectroscopy, the degradation process dominated by non-radical pathways was determined. At the same time, O2·- and 1O2 were closely related, and a significant impact of quenching O2·- on the reaction was observed. The non-radical approach made the system excellent performance over a wide pH range and in the presence of multiple anions. The experiments of reusability confirmed the stability of the material. Its catalytic performance was restored after low-temperature pyrolysis. This research supports the use of endogenous nitrogen in biomass. It provides more options for advanced oxidation process application and marine resource development.