Surface Charges of Polystyrene Nanoplastics Affect Their Distribution in Mice

Micro- and nanoplastics can enter the human body through ingestion, inhalation, and skin contact, and their distribution within the body and impact on health have attracted widespread attention. This study aimed to examine how particle size and surface charge influence the biodistribution of polystyrene nanoplastics (PS NPs) in mice following intravenous administration. Our results indicate that the majority of fluorescent PS NPs, regardless of their charge or size, predominantly accumulated in the liver, which is pivotal for filtration. Notably, negatively charged COOH-PS NPs exhibited significant accumulation in the lungs 30 min post-injection, in contrast to positively charged NH2-NPs. Specifically, 100 nm COOH-PS NPs demonstrated marked lung accumulation, implying that these anionic particles can more effectively traverse the vascular endothelial barrier. Subsequently, we analyzed the protein corona composition on the surface of nanoplastic particles and discovered vitronectin and fibrinogen as crucial plasma proteins interacting with negatively charged PS NPs. This corona facilitates integrin αIIbβ3 receptor-mediated phagocytosis by lung endothelial cells, accounting for the localization of PS NPs in the lungs. These findings underscore the significance of considering both surface charge and protein corona composition in assessing the safety of nanoplastics.