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

[Display omitted] •Nanometer-size (2–3 nm) β-CD@CeO2-x complexes were obtained with β-CD as stabilizer.•β-CD@CeO2-x complexes reveal high antiradical activity as •OH and O2– scavengers.•The ways to improve colloidal stability of β-CD@CeO2-x in biological media are shown. 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 β-CD@CeO2-x complexes with addition of β-CD on the stage of syntheses of NPs. As a result, highly stable colloidal solutions of nanometer-size (2–3 nm) β-CD@CeO2-x nanoparticles were obtained. The stabilization effect of β-CD molecules was shown. Obtained β-CD@CeO2-x complexes reveal high antiradical activity in the number of experiments (including •OH and O2– scavenging) related to Ce3+/Ce4+ redox switching in nanoceria. The aggregation behavior of β-CD@CeO2-x complexes in various biological media was studied and the ways to improve their stability were proposed.