A Co,N co-doped hierarchically porous carbon hybrid as a highly efficient oxidase mimetic for glutathione detection

Abstract

The past few years have witnessed rapid development of nanozymes in various fields. However, analytical applications of oxidase nanozymes are limited. Here, a novel oxidase nanozyme was fabricated by one-pot pyrolysis of ZIF-67. Benefiting from self-template synthesis and a nitrogen-rich precursor, the resulting product is a highly N-doped hierarchically porous carbon with well-dispersed Co nanoparticles. It shows a typical oxidase mimicking property to efficiently catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), 1,2-diaminobenzene, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt by oxygen to produce a color reaction without the need for H2O2. Reactive oxygen species (ROS) measurements indicate that 1O2 and O2− radicals are the main ROSs in the TMB–Co,N co-doped hierarchically porous carbon (Co,N-HPC) system. The high surface area and hierarchical pores of Co,N-HPC facilitate rapid diffusion of dissolved oxygen to the catalytic active sites, resulting in the novel and efficient oxidase nanozyme characteristic of Co,N-HPC. On account of the inhibiting effect of glutathione on TMB oxidation, a rapid and highly sensitive colorimetric assay is proposed for its detection. This assay has a linear concentration range from 0.05 to 30 μM and a limit of detection of 36 nM (3σ). The proposed method was successfully applied to glutathione quantification in biological samples.