Titanium doping reduces superoxide dismutase activity, but not oxidase activity, of catalytic CeO2 nanoparticles

In this paper we report the enzymatic properties of Ti-doped CeO2 nanoparticles. The superoxide dismutase activity of Ti-doped nanoparticles is reduced in comparison to undoped nanoceria. In contrast, the oxidase activity of these nanoparticles was unchanged. The change in enzymatic activity was accompanied by a dramatic change in shape to a spherical nanostructure. In addition to reporting a new type of enzymatically-active nanoparticle, Ti-doped cerium oxide nanoparticles are well suited for biological applications. Keywords nanoparticles; nanoceria; enzymatic activity; metal oxides Although enzymatic activity is traditionally thought of as a biochemical function of proteins, recent studies have shown that several inorganic nanoparticles display enzymatic activities. Among these enzymatic activities are peroxidase, oxidase, catalase, and superoxide dismutase [1-5]. Indeed, complex biomimetic characteristics such as bacterial-like motility are exhibited when certain nanoparticles catalyze chemical reactions [6]. For example, cerium oxide nanoparticles (nanoceria) exhibit superoxide dismutase (SOD) mimeti