Determination Of Nanoplastics And Its Effect On β-amyloid Polypeptide Aggregation

The massive use of plastics increases the accumulation of nanoplastics in the environment.Nanoplastics that enter the body through ingestion of food and drinking water can affect the normal function of proteins and cause cellular and tissue toxicity.The current detection methods for nanoplastics are mainly based on spectroscopy and mass spectrometry.These methods rely on large instruments and cannot meet the requirements of low cost and routine detection.In contrast,electrochemical methods offer great advantages in terms of rapid,sensitive,simple and inexpensive detection of various analytes.Therefore,this paper constructs a quantitative detection method for nanoplastics based on electrochemical technology.The effect of nanoplastics on the aggregation process ofβ-amyloid peptide（Aβ）was also investigated in a simulated cell-crowding environment.The main research works are as follows:（1）Simple quantification of nanoplastics was carried out using differential pulse voltammetry（DPV）.Positively-charged Au nanoparticles was coated onto Au electrode to selectively capture negatively-charged nanoplastics in aqueous environment.Subsequently,the nanoplastics were recognized by the signal molecule ferrocene via the hydrophobic interaction and determined by DPV.This method was used to detect polystyrene,polypropylene,polyethylene and polyamide nanoplastics with a linear range of 1μg·L^-1-100μg·L^-1 and a detection limit of 0.7-0.9μg·L^-1.Based on it,the nanoplastics released from several typical food packages were assayed.Teabags were revealed with significant nanoplastic release while instant noodle boxes,paper cups,take-out boxes release slightly.In addition,the recoveries of the actual samples spiked with the assay deviated within 10%,confirming the accuracy of the method.This work provides a sensitive,low-cost and simple method without complicated instrument and pretreatment,which is of great significance for the routine detection of nanoplastics.（2）Unlike in vitro solution conditions,in vivo biochemical processes generally occur in a highly crowded cellular environment.This crowded environment can affect various reaction equilibria and alter reaction pathways and kinetics.Based on this,we systematically investigated the effect of nanoplastics on Aβaggregation process in a simulated cellular crowded environment.Polystyrene nanoplastics（PNPs）were chosen as a model and Ficoll 70 as a crowding agent.Thioflavin T fluorescence results showed that PNPs at 1μg·L^-1-10 mg·L^-1 could significantly promote Aβaggregation.The nucleation rates of different concentrations of Aβ_1-42 and Aβ_1-40 in the presence of 10 mg·L^-1 PNPs in the buffer increased by 30%-120%and 20%-140%,respectively,and the growth rate decreased by 10%-20%and 10%-60%.In contrast,the nucleation rate increased by 50%-2800%and 20%-710%in the crowded environment,and the growth rate was 0.5-1.1 and 0.8-1.2 times higher than its incubation alone.This indicates that PNPs mainly accelerated the nucleation step of Aβand had less effect on the fiber growth process.The interaction mechanism between Aβand PNPs was preliminarily investigated,and the particle size data indicated that the conversion of Aβmonomers to aggregated nuclei and aggregated nuclei-induced fibrillation on the hydrophobic surface of PNPs were carried out simultaneously.The formation of a large number of aggregation nuclei within the system accelerates the rate of fibrosis in the early stages of Aβaggregation.Whereas the fibrotic process of Aβis closely related to the pathogenesis of Alzheimer’s disease（AD）,the promotion of Aβaggregation by PNPs suggests that human ingestion of nanoplastics may induce or exacerbate the course of AD.This study facilitates the understanding of the potential effects of nanoplastic ingestion on human health and the assessment of its biotoxicity.