Formation of protein corona on nanoparticles with digestive enzymes in simulated gastrointestinal fluids.

The protein corona (PC) that defines the biological identity of nanoparticles in the blood is well known, but no comprehensive and systematic study has been conducted yet on the formation of PC in the gastrointestinal environment. Thus, this study aimed to explore the interaction between model polystyrene nanoparticles (PS-NPs) with 50-100 nm and three digestive enzymes, namely, pepsin, α-amylase, and trypsin. Results showed that the thickness of the PC formed by α-amylase and trypsin was 25-100 and 50-100 nm, respectively. The zeta potential values of PS-NPs after incubation significantly increased. The fluorescence quenching and ultraviolet visible absorption spectra suggested the interaction between the nanoparticles and the enzymes occurred. Synchronous fluorescence spectra showed that the PS-NPs could induce the microenvironmental change in digestive enzymes. The thermodynamic parameters suggested that the interaction was mainly driven by the hydrogen bonds and van der Waals forces.