PEGylation-Driven Remodeling of the Protein Corona on PLGA Nanoparticles: Implications for Macrophage Recognition

The formation of a Protein Corona (PC) on the surface of nanoparticles (NPs) is a critical event that shapes their biological identity and governs interactions with the immune system. In this study, we investigated the composition of the PC formed on mixtures of PLGA and PEG–PLGA NPs, aiming to elucidate the link between NPsurface chemistry, proteomic fingerprint in cell culture medium, and uptake by bone marrow-derived macrophages (BMDMs). NPs showed different sizes but comparable actual PEG amount exposed on the surface, which is significantly lower than the theoretical values. The PC, isolated using a standardized microfiltration protocol, revealed distinct patterns of protein adsorption as a function of the PEG density. Uptake studies in BMDMs revealed a strong inverse relationship between PEG surface density, PC composition, and macrophage internalization, supporting the hypothesis that the opsonin/dysopsonin balance is more critical than a single protein interaction. In conclusion, this work demonstrates that the PEG surface density is not the only determinant of PC composition. These findings underscore the importance of rigorous surface characterization and PC profiling to predict and tune nanocarrier performance in vivo.