Stable nanometer-size beta-cyclodextrin-CeO2-x colloidal nanoparticles with high free radical scavenging activity

Cyclodextrin (CD) molecules are well-known for their ability to form inclusion complexes with hydrophobic molecules, including small drug molecules and lipophilic antioxidants. The combination of nanoparticles (NPs) with antioxidant properties (so-called nanozymes) and hydrophobic antioxidant molecules using CD@NP complexes can increase sufficiently the antioxidant efficiency of both components due to synergistic effect. Here we propose the new method of obtaining beta-CD@CeO2-x complexes with addition of beta-CD on the stage of syntheses of NPs. As a result, highly stable colloidal solutions of nanometer-size (2-3 nm) beta-CD@CeO2-x nanoparticles were obtained. The stabilization effect of beta-CD molecules was shown. Obtained beta-CD@CeO2-x complexes reveal high antiradical activity in the number of experiments (including center dot OH and O2- scavenging) related to Ce3+/Ce4+ redox switching in nanoceria. The aggregation behavior of beta-CD@CeO2-x complexes in various biological media was studied and the ways to improve their stability were proposed.