CHEMISTRY AND MATERIAL SCIENCE

UV-tuning the redox properties of nanoscale cerium dioxide and its enzyme conjugates

M. M. Sozarukova^a, A. D. Filippova^a, D.-M. V. Ratova^b, I. V. Mikheev^b, E. V. Proskurnina^a, A. Y. Baranchikov^a, V. K. Ivanov<sup>a

a</sup> Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
^b Analytical Chemistry Division, Chemistry Department, M. V. Lomonosov Moscow State University, Moscow, Russia

Abstract: This study investigated the redox properties of cerium oxide nanoparticles (CeO$_2$ NPs) and their conjugates with superoxide dismutase (SOD) or horseradish peroxidase (HRP) as well as the UV-induced modulation of these properties. UV exposure non-monotonically decreased the SOD-like property of the bare CeO$_2$ NPs. The CeO$_2$ conjugates with enzymes were analyzed both immediately after preparation and after being aged for 3 h. Chemiluminescence assays showed the synergistic effect for the CeO$_2$-SOD conjugates which showed high SOD activity. Additionally, CeO$_2$ NPs enhanced the stability of the conjugated SOD under UV exposure thus demonstrating a photoprotective function. The CeO$_2$-HRP conjugates demonstrated lower prooxidant activity compared to the bare enzyme, however higher stability under UV irradiation. The effect of UV radiation on CeO$_2$-HRP conjugates was found to be multidirectional and depended on the incubation time of the CeO$_2$ NPs with the enzyme. The results demonstrated that CeO$_2$-enzyme conjugates offer tunable dual functionality and UV light could be an important parameter affecting their redox properties. The latter effect should be taken into account for designing advanced cosmeceutical formulations.

Keywords: nanoceria, superoxide dismutase, peroxidase, UV irradiation, enzyme, conjugate, redox modulation, photoprotection.

Received: 29.10.2025
Accepted: 16.11.2025

Language: English

DOI: 10.17586/2220-8054-2025-16-6-791-801