Protein corona formed on the TiO2 nanoparticles promotes the hydrolysis of collagen in simulated gastrointestinal fluids

Titanium dioxide nanoparticles (TiO 2 NPs) could interact with proteins in foods and gastrointestinal fluids, thus changing the properties and functions of proteins. Many research articles have only studied the interactions between TiO 2 NPs and digestive enzymes or the gastrointestinal fate of TiO 2 NPs without considering the effect of food matrix. Therefore, the interactions between TiO 2 NPs and trypsin and its effects on the digestion of collagen in vitro were investigated. Results showed that the functionalization of amino acids (Asp, and Ser) significantly harmed the adsorption of trypsin by TiO 2 NPs. The fluorescence quenching and isothermal titration calorimetry confirmed that the hydrogen bond and van der Waals force played an essential role in the interactions between TiO 2 NPs and trypsin. The β-sheet content of trypsin bound to TiO 2 NPs decreased from 52.40% to 50.73% while the random coil content increased from 20.20% to 22.63%. Binding sites were identified by molecular docking . Additionally, the digestibility of collagen was improved in vitro in the presence of TiO 2 NPs analyzed by SDS-PAGE, hydroxyproline quantification, and the antioxidation of digested products. Hydroxyproline concentration increased by nearly 25% and ABTS radical scavenging rate increased by 50%. This study provides a new insight into the impact of nanoparticles on gastrointestinal digestion.