Iron oxide (Fe3O4) nanoparticles (NPs) are widely utilized in water treatment, remediation, and biomedical applications. They are also identified as constituents of airborne particulate matter, heightening the risk of human exposure and potentially adversely affecting health. NPs inevitably form a protein corona in biological fluids, which redefines their identity and governs cellular interactions. Although the plasma protein corona has been extensively characterized, its intracellular fate following Fe3O4 uptake remains largely unresolved. During Fe3O4 extracellular-to-intracellular trafficking, protein coronas evolve dynamically across biological barriers; however, the remodeling, degradation, or retention of plasma proteins carried into cells by Fe3O4 remains unclear. In this study, we delineate the evolution of plasma-derived coronas from extracellular to intracellular environments. Proteomic analysis revealed that the initial plasma proteins were dynamically replaced by higher-affinity intracellular proteins upon Fe3O4 internalization. Furthermore, we emphasize the active role of the cell membrane in protein corona remodeling, with high-abundance fibrinogen being retained at the cell membrane through receptor regulation. These findings uncover a critical, previously overlooked dimension of protein-corona biology: the intracellular fate of plasma proteins dictates NPs' trafficking and toxicities, thereby linking environmental exposure to human health risk.
Zhu et al. (Mon,) studied this question.