This is a copy of the slides presented at the meeting but not formally written up for the volume.

Cerium oxide (ceria) can be considered as one of the most important rare earth oxides. In conjunction with the benefits of nanotechnology, it has found enormous applications in catalysis, sensors and biomedical applications. These applications stem from its ability to switch oxidation states between +3 and +4 depending on ambient conditions. Nanoceria has been shown to impart protection to cells against the reactive oxygen species (ROS) by our group. We have also established a preferential protection of the normal cells against radiation damage as compared to the tumor cells. These stimulating properties of nanoceria make it imperative to stabilize it in various aqueous and non-aqueous solvents for practical applications. Systematic engineering of nanoceria in media like poly (ethylene glycol) (PEG), dextran and glucose can be of great importance in biological applications. Dextran and PEG have been used extensively to stabilize nanoparticles in solution. Biocompatibility of these media can be exploited to disperse nanoceria inside the body to provide cell protection. Unlike most of the reported work, where a two step synthesis and re-dispersion strategy is used, nanoceria prepared under room temperature wet chemical synthesis shows active switching of oxidation states. In the present work we report the successful synthesis of nanoceria in glucose, dextran and their effect on stability of nanoparticles in acidic and basic media. The role of polyhydroxyl group in complexing ceria and their subsequent oxidation/hydrolysis is monitored using UV-VIS spectroscopy. The nanoparticle characterization using high resolution transmission electron microscopy (HRTEM) for structure and morphology and X-ray Photoelectron Spectroscopy (XPS) for oxidation states will be reported. An effort will be made to present the quantitative analysis of various results.