Low-Temperature Inactivation of Enzyme-like Activity of Nanocrystalline CeO 2 Sols

Colloidal solutions of CeO 2 stabilized by citrate ions were synthesized by hydrolysis of cerium(III) nitrate in an alkaline medium in the presence of citric acid at 20–80°C. The enzyme-like activity of the obtained materials was analyzed by the method of activated luminol chemiluminescence involving hydrogen peroxide. The dependence of the peroxidase-like activity of CeO 2 on the preparation conditions of colloidal solutions was shown for the first time. On average, an increase in the temperature of heat treatment of CeO 2 sols by every 10°C in the range of 20–80°C decreases the enzyme-like activity approximately 1.2-fold.