Influences of a standardized food matrix and gastrointestinal fluids on the physicochemical properties of titanium dioxide nanoparticles Yan Li, * Kun Jiang, Hui Cao, Min Yuan and Fei Xu * The fast-growing applications of engineered titanium dioxide nanoparticles (e-TiO2-NPs) in the food and pharmaceutical industry in production, packaging, sensors, nutrient delivery systems, and food additives enhance the possibility of oral exposure. Physicochemical transformations may occur when e-TiO2-NPs are incorporated into a food matrix and pass through the human gastrointestinal tract (GIT),