Toxicological Study Of Typical Emerging Contaminants On Human Normal Colonic Epithelial Cells

The continuous production and development of emerging contaminants have a wide-ranging impact on our lives.Emerging contaminants have the characteristics of wide source,complex control,concealment and persistence,and their accumulation in environment and organism may cause unknown health risks.Emerging contaminants include endocrine disruptors,antibiotics,nanomaterials,and disinfection by-products（DBPs）.Emerging contaminants can be ingested by human body through many ways,and cause certain toxic effects,threatening human health.MXene is a promising material,but its related health risk research is relatively scarce.With the rapid update of detection technology,new DBPs are being identified and discovered,and the related health risk research needs to be carried out.So this study focused on two-dimensional nanomaterials MXene and DBPs,and used in vitro cell model to explore their cytotoxicity and toxic mechanism.As a relatively new nano-material,MXene is characterized by its high mechanical strength,good biocompatibility,high surface area,stable electrochemical properties and high hydrophilicity,once developed,it has attracted wide interest from researchers.There are more than 130 known MXene materials with different structural components,it shows great application potential in the fields of optoelectronics,electromagnetic interference shielding,energy storage,biomedicine and environmental engineering.Aging is an important behavior of MXene in the environment,and it is very important to explore the effects of aging on the toxicity of MXene in order to identify its environmental health risks.Based on this,we used FHC cell model to compare the toxic effects of pre-aging（Ti₃C₂T_x,Ti₃CNT_x）and post-aging（o-Ti₃C₂T_x,o-Ti₃CNT_x）MXene.Firstly,the physical and chemical properties of MXene were characterized before and after aging,and the effects of aging process on the size,morphology and chemical composition of MXene were clarified.In addition,the toxicity evaluation results of the four materials showed that Ti₃C₂T_x and Ti₃CNT_x exhibited stronger cytotoxicity in the range of 0-100μg/m L exposure dose relative to aging.Through the methods of fluorescence staining,inhibitor contrast test and Flow cytometry test,we have determined that inducing apoptosis is the main cause of Ti₃CNT_x-induced decrease in cell viability.We continued to use cell electron microscopy,q-PCR and Western blot to confirm that Ti₃CNT_x induced significant increase of intracellular ROS and GHS,this results in cell-induced Bcl-2 or mitochondrial-mediated endogenous apoptosis,leading to a decrease in overall cell viability.In summary,the type and aging of MXene are key factors affecting its cytotoxicity.DBPs is an important product in the process of drinking water disinfection and an important component of new pollutants.Currently,new DBPs are being identified and discovered,and the health risks of most of these substances remain unknown and not effectively regulated.Worryingly,some previous studies have suggested that some DBPs may be at high toxic risk,so effective identification of critical toxic DBPs is critical to ensuring people’s water safety.Based on this,we take water samples from different treatment process sections of a water plant in Guangzhou as research objects,and collect raw water（W1）,water to be filtered（W2）,sand filtered（W3）,carbon filtered（W4）,effluent（W5）,and pipe network water（W6）,respectively,based on the results of non-target detection and DNA damage test,the key toxic DBPs components in water samples from different treatment processes were systematically analyzed and identified.First,we greatly improved the detection efficiency of DBPs in water samples by means of enrichment,and then carried out non-target detection for each water sample by UPLC-MS,the dynamic change of water quality in the process of water treatment is analyzed.The results showed that only W1,W2,W3 water samples showed obvious comprehensive cytotoxicity to FHC cells,and the toxic effect was enhanced in turn.In the effect of DNA damage,W1>W3>W6>W5>W4,W2 did not show DNA damage-inducing ability.Based on the above results,we analyzed the results of water quality analysis and cell effect,and quickly screened out a part of the list of suspected toxic DBPs,the changes of relative content of listed substances in the process of water treatment were described.This work strengthens our understanding of the potential health risks of DBPs and provides a theoretical reference for scientific supervision of key toxic DBPs components in drinking water and optimization of targeted water treatment processes.Overall,this study focused on health risk studies of the typical emerging contaminants MXene and DBPs,revealing the cytotoxic mechanism of MXene and its influencing factors,the method of screening the suspected toxic DBPs based on the end point of cell effect was established,which provided theoretical support for the safe application of Mxene and water safety,and enriched the theoretical system of health risk research of emerging contaminants.