Toxicity Mechanism Of Nanoplastic Particles To Zebrafish Larvae

Microplastics are widely present worldwide and pose a significant risk to the safety of the ecosystem,animal and human health,therefore are receiving attention from the world.Microplastics break down into smaller particle size nanoplastics,which are more abundant in the environment than microplastics and have a greater ability to penetrate the barriers of organisms,thus causing a greater threat to the natural environment and organisms.In this study,we used laboratory simulation of water exposure,investigated the neurotoxic effects of nanoplastics on zebrafish embryos using zebrafish（Danio rerio）as a model organism,the discrepancy in the developmental toxic effects of nanoplastics with different functional groups on zebrafish embryos and the deep mechanism.Carboxyl（-COOH）-modified polystyrene nanoplastics（PS-COOH）had neurotoxic effects on zebrafish.First,compared with the control group（Ctr）,PS-COOH nanoparticles caused active swimming behavior in zebrafish larvae,with significant increases in acetylcholinesterase activity and dopamine levels.Deep analysis by proteomics and metabolomics revealed that PS-COOH nanoparticles caused dysregulation of expression levels of various neurological related proteins and metabolites in zebrafish larvae.Especially the expression of Parkinson’s disease-associated protein（PARK7）was upregulated,which was the opposite of the expression levels in Parkinson’s disease patients,suggesting that PS-COOH nanoparticles caused neuroexcitatory symptoms in zebrafish larvae through the reverse Parkinson’s pathway.The protein molecular structure revealed that PS-COOH binds more readily to the neuroprotein PHGDH and causes its aggregation,increasing its expression level and therefore causing neuroexcitatory symptoms in zebrafish larvae.Nanoplasticcs with different functional groups have different charges on the surface therefore cause different toxic effects on organisms.In this paper,studies were conducted using amino（-NH₂）-modified polystyrene nanoplastics（PS-NH₂）and-COOH modified polystyrene nanoplastics（PS-COOH）.PS-NH₂entered the interior of zebrafish embryos earlier than PS-COOH.PS-NH₂caused higher mortality and hatching delay in zebrafish embryos than PS-COOH at the same exposure concentration,and only PS-NH₂caused developmental malformations.PS-NH₂caused more significant inflammatory effects than PS-COOH on zebrafish larvae and enhanced the immune response of zebrafish larvae.After an in-depth proteomic and metabolomic analysis,it was found that PS-NH₂caused hyperglycemia in zebrafish larvae compared to PS-COOH and may reduce pyruvate expression.PS-NH₂enhanced levels of arginine,which provides nutrients to tumor tissues,and increased expression levels of proteins which are significantly associated with tumors,led to higher developmental toxicity.This paper will provide some reference basis for the neurotoxic effects of nanoplastics and the discrepancy of developmental toxic effects of nanoplastics with different functional groups and the deep mechanism analysis.