The Opposite Roles of Benzo[

Microplastics (MPs) have recently become a worldwide concern as newly emerging airborne pollutants, particularly because they can associate with polycyclic aromatic hydrocarbons (PAHs). Upon inhalation, MPs encounter bronchoalveolar lavage fluid (BALF), resulting in the formation of protein coronas that govern their biological identity and behavior. Herein, polystyrene (PS) MPs were selected as model MPs, and PS@BALF, PS@BaP, and PS@BaP@BALF MPs were simultaneously prepared to study the combined effects of eco- and biocorona formation for the first time. We investigated the compositions of protein coronas formed on PS and PS@BaP MPs in BALF, revealing that BaP adsorption significantly altered protein species and relative abundance. It was found that the protein corona enhanced uptake of PS MPs by RAW264.7 macrophages through caveolin-mediated endocytosis, with SP-A identified as a key mediator. Moreover, cytotoxicity assessments demonstrated that the protein corona mitigated membrane damage and apoptosis induced by MPs, whereas BaP adsorption significantly intensified cellular toxicity, oxidative stress, and apoptotic responses, illustrating the opposing effects of two coronas. Notably, the protein corona contributed to oxidative stress, potentially due to increased cellular uptake. Finally, toxicoproteomics analysis elucidated potential mechanisms of MP-induced toxicity. These findings underscore the importance of incorporating both pollutant adsorption and biomolecular corona formation.