Protein corona formation around inorganic nanoparticles: Food plant proteins-TiO2 nanoparticle interactions

Abstract

Abstract Powdered titanium dioxide (TiO2) is used as a whitening agent in certain food products to enhance their optical properties. Food-grade TiO2 (E171) contains a substantial proportion of nano-sized particles, which have been linked to adverse health effects. Plant-based foods are becoming increasingly popular in the human diet. For this reason, we examined the interactions between TiO2 nanoparticles and a number of plant proteins: glutenin, gliadin, zein, and soy protein. All four proteins formed coronas around the TiO2 nanoparticles, with the thicknesses of the adsorbed layers (4–60\xa0nm) depending on the protein type. The morphologies of the protein coronas were elucidated using transmission (TEM) and scanning (SEM) electron microscopy. The surface potentials of the coated TiO2 nanoparticles also depended on protein type, changing from −18 mV to +22.6, +61.4, +18.9, and −15.6\xa0mV 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. 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.