The peroxidase and oxidase-like activity of NiCo2O4 mesoporous spheres: Mechanistic understanding and colorimetric biosensing

Abstract

The synthesized NiCo₂O₄ mesoporous spheres (MS) displayed intrinsic peroxidase and oxidase-like activity were firstly reported. The catalytic mechanism of the oxidase-like activity of NiCo₂O₄ MS was analyzed in detail using the electron spin resonance (ESR) method. It is found that NiCo₂O₄ MS could directly oxidize 3,3',5,5'-tetramethylbenzidine (TMB) but did not produce ¹O₂ and ·OH. And the mechanism of the peroxidase-like activity of NiCo₂O₄ MS was also verified that the oxidation of TMB stemmed from not only ·OH but also ¹O₂. Based on the NiCo₂O₄ MS showed excellent peroxidase-like activity over a broad temperature range, especially at normal body temperature, a detection tool was designed for glucose determination in diabetics' serum samples. And this detection method based on NiCo₂O₄ MS gave a lower limit of detection than the method using Co₃O₄ NPs and NiO NPs, as the single-component oxides of NiCo₂O₄. Our study may open up the possibility to make a great influence on the next generation of enzyme mimetics system.

Keywords: Colorimetric biosensing; Electron spin resonance; Glucose detection; NiCo(2)O(4) mesoporous spheres; Peroxidase and oxidase-like activity.