Formation of Protein Corona on Nanoparticles with Digestive Enzymes in Simulated Gastrointestinal Fluids

The protein corona (PC), which 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 PCs in the gastrointestinal environment. Thus, this study aimed to explore the interaction between model polystyrene nanoparticles (PS-NPs) of 50-100 nm and three digestive enzymes, namely, pepsin, alpha-amylase, and trypsin. Results showed that the thicknesses of the PCs formed by alpha-amylase and trypsin were 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 that interactions between the nanoparticles and the enzymes occurred. Synchronous fluorescence spectra showed that the PS-NPs could induce microenvironmental changes in digestive enzymes. The thermodynamic parameters suggested that the interaction was mainly driven by hydrogen bonds and van der Waals forces.