Reactivity of nanoceria particles exposed to biologically relevant catechol-containing molecules

The interaction of nanoceria particles with catechol-like molecules of physiological importance, including dopamine, norepinephrine, epinephrine, serotonin, 3,4 dihydroxyphenylaceticacid (DOPAC) and L-3-(3,4-dihydroxyphenylalanine) (L-DOPA) was studied to obtain predictive information of their behavior in biological systems. A suite of complementary techniques including UV-Vis spectroscopy, electrochemistry, dynamic light scattering (DLS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) demonstrated alteration in the spectral, redox and surface properties of nanoceria exposed to these molecules in an aqueous environment. Binding of catechol to the surface of nanoceria diminished the oxidase-like activity of these particles against an organic dye, TMB (3,3,5,5-tetramethylbenzedine), but enhanced their ability to react with and inactivate reactive oxygen species. Therefore, the reactivity of these particles can be modulated by addition of catechol-like molecules. These findings can help develop predictive models of the behavior and potential effects of nanoceria particles in complex environments.