Highly sensitive colorimetric sensing for ascorbic acid utilizing Co3O4@MnO2 hollow nanocubes as oxidase mimic

The development of oxidase mimic with favorable catalytic activity is of great significance for the rapid and convenient detection of ascorbic acid (AA). Herein, in this work, a synergistic regulation strategy of heterogeneous interface and hollow structure is proposed to effectively solve the problem of limited active sites obtained with Co3O4. The charge rearrangement at heterointerface could improve the catalytic activity of oxidase mimic. Moreover, the hollow nanocubes structure could increase specific surface area and provide rich active sites. As a result, the target material possesses enhanced oxidase-like catalytic activity and desirable stability compared to bare Co3O4 and MnO2, which also catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) to form a blue product (ox-TMB) even without hydrogen peroxide. Ox-TMB is reduced to TMB owing to the strong reducibility of AA, which represents a decrease in absorbance at 652 nm and a colorless solution. Moreover, an efficient biosensing method for the detection of AA is developed. The relative absorbance (∆A) of the sensing platform is linearly related to the concentration of AA in the range of 0-200 μM, and the detection limit is 0.11 μM. This work provides a novel method for the rapid, cost-effective and sensitive detection of AA, and possesses a wide range of potential application value.