Chromium decorated leaf-like N-doped carbon anchoring with active Cr-Nx sites as oxidase mimics for isoniazid sensing

Research about constructing transition metal-based N-doped carbon nanozymes with high-performance for sensing applications has attracted great attention. Here, a novel Cr decorated N-doped carbon (Cr-NC) derived from zeolite imidazolate framework-leaf with unique Cr-Nx active sites was developed via pyrolysis strategy. The nanosheet structure endowed Cr-NC with highly exposed active sites for promoting O2 adsorption and cleavage into reactive OH, O2− and 1O2, for oxidizing 3,3′,5,5′-tetramethylbenzidine (TMB), showing oxidase-like activity. Compared with that of N-doped carbon (NC), the catalytic activity of Cr-NC oxidase mimic was increased by 19.55 times. Cr species doping in carbon matrix could promote electron transfer ability of Cr-NC and Cr-Nx anchoring in Cr-NC was the major active sites in improving the oxidase-like performance of NC. The Cr-NC displayed a good affinity to TMB and a fast reaction velocity, showing the Km value of 0.54 mM and the Vmax of 3.03 × 10−7 M/s. Since isoniazid (INH) contains hydrazine groups, which inhibits the oxidation of TMB, a sensitive and highly selective assay for INH was established based on the oxidase-like activity of Cr-NC. The linear response of the detection platform to INH ranges from 0.25 to 50 μM with the detection limit (3σ/k) of 0.22 μM and the relative standard deviation (RSD, n = 3) less than 3.5%. The platform has been successfully applied to the determination of INH in real pharmaceutical preparations.