Intrinsic oxidase activity of cerium oxide nanoparticles facilitate the detection of cancer biomarkers and cancer cells
J.M. Perez, A. Asati, S. Santra, C. Kaittanis, S. Nath
University of Central Florida, US
Keywords: nanoceria, cerium oxide nanoparticles, oxidase activity, immunoassay
Abstract:Nanomaterials exhibit unique size-dependent physical properties. Thus, identifying novel properties of these materials at the nanoscale, and their applications in energy, catalysis and medicine, among others, is an area of current and intense research. Cerium oxide has been widely used in catalytic converters for many years, but only recently its interesting nanoscale-derived properties have been elucidated. Among the most interesting properties that nanoceria (cerium oxide nanoparticles) possesses is its ability to behave as a potent antioxidant at pH 7, due to the reversible switching from two oxidation states (Ce+3 and Ce+4). Recently, we reported that the antioxidant activity of nanoceria is pH-dependent, and this property can be used for the selective protection of normal tissue during cancer chemotherapy and radiotherapy. In the present study, we investigated the oxidase activity of nanoceria, which is also pH-dependent. In addition to this, we found that (i) at pH 4 nanoceria oxidized various organic substrates without the need of an oxidizing agent, (ii) nanoceria’s oxidase kinetics can be modulated via the thickness of the polymer coating, and (iii) nanoceria can be used in immunoassays via the oxidation of sensitive dyes that facilitate detection of biological targets.