Protein Corona Formation and Interaction between Food Plant Proteins and Titanium Dioxide Nanoparticle

Powdered titanium dioxide (TiO 2 ) is widely used as a whitening agent in certain foods to enhance their optical properties. Food‐grade TiO 2 (E171) contains a substantial proportion of nano‐sized particles, which have been linked to adverse health effects. It is important to understand how TiO 2 nanoparticles behave in foods and the human gut. For this reason, we examined the interactions between TiO 2 nanoparticles and four model proteins and demonstrated that glutenin, gliadin, soy protein and zein can be adsorbed onto TiO 2 nanoparticle surfaces and form a protein corona. All four proteins formed coronas around the TiO 2 nanoparticles, with the thicknesses of the adsorbed layers (4‐60 nm) depending on protein type. The morphology of the protein coronas was elucidated using transmission and scanning electron microscopy. The formation of the protein corona changed the size and surface charge of the TiO 2 nanoparticles. The surface potentials of the coated TiO 2 nanoparticles also depended on protein type, changing from ‐18 mV to +22.6, +61.4, +18.9, and ‐15.6 mV for glutenin, gliadin, zein, and soy protein, respectively. Fluorescence quenching, circular dichroism and infrared spectroscopy confirmed that interactions occurred between the nanoparticles and plant proteins that altered their secondary structures. Our findings provided valuable information on the changes in the structure and physicochemical properties of TiO 2 nanoparticles after being incubated with various plant proteins. In addition, these findings show the importance of taking into account the interactions of ingested nanoparticles with ingredients in the surrounding food matrix, and provide a better understanding of the effect of nanoparticles on plant proteins. This knowledge is important for predicting the behavior of nanoparticles in complex food matrices and within the human gastrointestinal tract, which could lay the foundation for further studies of protein coronas in vivo .