Dynamic Evolution of Fe₃O₄ Nanoparticles' Protein Corona during Extracellular to Intracellular Trafficking: The...

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.