Inorganic nanoparticles enhance the production of reactive oxygen species (ROS) during the autoxidation of l-3,4-dihydroxyphenylalanine (l-dopa)

► Novel method to evaluate the chemical ROS generating potential of emerging inorganic NPs reacting with biomolecules. ► The interaction of NPs with biological phenolic compounds enhanced ROS generation. ► Chemical ROS formation by NPs interacting with phenolics point to be an important mechanism for oxidative stress. ► Mn2O3 NPs could directly oxidize a common ROS indicator dye, dichlorofluorescin.