Synthesis of Cerium Oxide Nanoparticles in a Bacterial Nanocellulose Matrix and the Study of Their Oxidizing and Reducing Properties.

A soft synthesis of nanoceria with non-stoichiometric composition (33% Ce3+/67% Ce4+) named CeO2 NPs in bacterial cellulose (BC) matrix in the form of aerogel and hydrogel with controlled CeO2 NPs content was proposed. The advantage of CeO2 NPs synthesis in BC is the use of systemic antacid API-trisamine as a precursor, which did not destruct cellulose at room temperature and enabled a reduction in the duration of synthesis and the number of washes. Moreover, this method resulted in the subsequent uniform distribution of CeO2 NPs in the BC matrix due to cerium (III) nitrate sorption in the BC matrix. CeO2 NPs (0.1-50.0%) in the BC matrix had a fluorite structure with a size of 3-5 nm; the specific surface area of the composites was 233.728 m2/g. CeO2 NPs in the BC-CeO2 NPs composite demonstrated SOD-like activity in the processes of oxidation and reduction of cytochrome c (cyt c3+/cyt c2+), as well as epinephrine to inhibit its auto-oxidation in aqueous solutions by 33-63% relative to the control. In vitro experiments on rat blood showed a decrease in the MDA level and an increase in the activity of antioxidant defense enzymes-SOD by 24% and G6PDH by 2.0-2.5 times. Therefore, BC-CeO2 NPs can be proposed for wound healing as antioxidant material.

Antioxidant Activity of New Copolymer Conjugates of Methoxyoligo(Ethylene Glycol)Methacrylate and Betulin Methacrylate with Cerium Oxide Nanoparticles In Vitro.

The synthesis of two new copolymer conjugates of methoxyoligo(ethylene glycol)methacrylate MPEGMA and betulin methacrylate BM was developed via RAFT polymerization. The molar content of BM units was equal to 9-10 and 13-16 mol%, respectively (HPLC, 1H and 13C NMR); molar weights were equal to 75000-115000. CeO2 NPs as a component of the hybrid material were synthesized for the preparation of the composition with copolymer conjugates of MPEGMA and BM. We showed a significant increase in G6PDH and GR activities by 21-51% and 9-132%, respectively, which was due to the increase in NADPH concentration under the action of copolymers in vitro. The actions of copolymers and CeO2 NPs combination were stronger than those of the individual components: the SOD activity increased by more than 30%, the catalase activity increased dose-dependently from 13 to 45%, and the GR activity increased to 49%. The maximum increase in enzyme activity was observed for the G6PDH from 54% to 151%. The MDA level dose-dependently increased by 3-15% under the action of copolymers compared with the control, and dose-dependently decreased by 3-12% in samples containing CeO2 NPs only. CeO2 NP-copolymer compositions can be used for the design of new biomimetic medical products with controlled antioxidant properties.