Interactions between TiO2 nanoparticles and plant proteins: Role of hydrogen bonding

Titanium dioxide (TiO 2 ) particles are widely employed in foods and supplements as lightening agents. A substantial fraction of the particles in commercial TiO 2 ingredients fall within the nanoscale, i.e., they have diameters below 100 nm. A biocorona can form around TiO 2 particles when they are incorporated into food matrices containing plant proteins . In this study, we investigated the molecular interactions between two hydrophobic plant proteins (gliadin and zein) and four types of surface-modified TiO 2 nanoparticles (TCN, TCN-1, TCN-2 and TCN-3). Ultraviolet–visible absorption, fluorescence quenching, and Fourier transform infrared spectroscopy indicated that the plant proteins interacted with the surfaces of the TiO 2 nanoparticles, resulting in changes in their molecular conformations . Quartz crystal microbalance analysis indicated that the mass of the hard corona increased as the number of hydroxyl groups on the surfaces of the TiO 2 nanoparticles increased, which implied that hydrogen bonding played an important role in the formation of the biocorona. These results provide a better understanding of the interactions that may occur in food matrices containing both plant proteins and TiO 2 nanoparticles.