Aging Processes Dramatically Alter the Protein Corona Constitution, Cellular Internalization, and Cytotoxicity of Polystyrene Nanoplastics

Humans are exposed to nanoplastics (NPs) through different routes, which raises critical concerns of related health effects. Due to their small sizes, NPs are accessible to the bloodstream and prone to interact with plasma proteins. NPs are susceptible to different aging processes before entering the human body, and it is plausible to evaluate the effect of aging on the physicochemical and biological properties of NPs. Here, we found that ultraviolet (UV) and ozone (O3) aging treatments caused the oxidation of polystyrene NPs, resulting in their differential adsorption characteristics toward plasma proteins. More importantly, UV and O3 aging led to reduced cellular internalization of NPs and herein relieved their cytotoxic effect. Together, our current finding further enriches the understanding of NPs' toxicity in a realistic scenario.