Ru doping enhance the peroxidase-like activity of CeO2 nanorods and application for cysteine determination at physiological temperature

It is an important task that exploring highly active peroxidase-like nanozymes to construct a real-time sensing platform for determining some biomolecules. Among the strategies of active improving of nanozymes, element doping is considered as one of the effective means. In this work, ruthenium (Ru) doping can enhance the peroxidase-like activity of cerium dioxide (CeO2). The peroxidase-like behaviors of Ru-doped CeO2 (Ru/CeO2) are evaluated using the chromogenic substrate 3,3,5,5-tetramethylbenzidine (TMB) and H2O2, respectively. As expected, Ru/CeO2 exhibits more excellent peroxidase-like activity than that of pure CeO2. The improvement of Ru/CeO2 catalytic activity is from the more exposed active sites, due to Ru doping and then defects producing. Furthermore, active species (•O2- and holes h+) were produced during the catalytic reaction. Notably, the catalytic activity of Ru/CeO2 at 37 °C (physiological temperature) still keeps the 95.12% of that at 40 °C, which is important for determination of biological samples. Combining the enhanced peroxidase-like activity of Ru/CeO2 with substrate TMB, a fast facile colorimetric platform for determination of Cysteine (Cys) has been constructed and validated by serum samples.