Synthesis of biocompatible dextran-coated nanoceria with pH-dependent antioxidant properties

The facile synthesis of monodisperse, water-soluble, and highly crystal-line dextran-coated nanoceria (DNC) are discussed. The improved water solubility of DNC show a unique pH-dependent antioxidant activity that could have important applications in the design of improved therapeutics and in tailoring its antioxidant properties. The aqueous solution of cerium nitrate and dextran is added to an ammonia solution under continuous stirring and on the formation of the cerium oxide nanocrystals, molecules of dextran coat the nanoparticle surface, preventing further growth and resulting in dextran-coated nanoceria. DNC have a good water stability even after several heating cycles with no sedimentation upon centrifugation at 8000 rpm for 30 min. Results indicate that the dextran coating does not affect the autocatalytic properties of nanoceria, as hydrogen peroxide and peroxyl radicals can diffuse through the hydrophilic dextran coating and oxidize Ce+3 to Ce+4.