Synthesis of water-soluble chitosan-coated nanoceria with excellent antioxidant properties

Nanoceria has been demonstrated as a potential antioxidative nano-drug. However, its short residence time in the body, toxic solvents involved in the synthesis processes, and especially the poor water solubility hinder its potential clinical applications. In this work, water-soluble chitosan-coated nanoceria particles (CNPs) are synthesized by a facile wet chemical route. The molar weight (MW) and concentration of chitosan do not affect the particles' size and the antioxidative activity of the CNPs over a wide range, and the mechanism is explored further. The behavior of CNPs over time and with a change of pH value were also examined. The CNPs reveal excellent antioxidative activity and stability over seven months at room temperature, and importantly, chitosan widens the pH range for the stable existence of water-soluble nanoceria. As a result, including its inherent advantages of wide availability, non-toxicity, biocompatibility and biodegradability, chitosan can also present the nanoceria with good water-solubility without interfering with its antioxidative activity. In other words, chitosan can enlarge the nanoceria stability over a higher pH range. These factors show the advantages of chitosan as a coating layer, promising the further application of nanoceria in biomedical and biotechnological fields.