Copper nanoparticles modified graphitic carbon nitride nanosheets as a peroxidase mimetic for glucose detection

Abstract

In this study, copper nanoparticles modified graphitic carbon nitride nanosheets (Cu NPs/g-C₃N₄) as a novel peroxidase mimetic were successfully prepared by the calcination of dicyandiamide–Cu²⁺ complex with the assistance of humic acid. The morphology and structure of the product were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The prepared Cu NPs/g-C₃N₄ was found to have highly peroxidase-like activity, which can rapidly catalyze the oxidation of peroxidase substance 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue color in the presence of H₂O₂. Accordingly, a simple, selective and fast colorimetric method was developed for H₂O₂ and glucose detection. The prepared Cu NPs/g-C₃N₄ exhibited low detection limits of 3.2 × 10⁻⁸ M and 3.7 × 10⁻⁷ M for H₂O₂ and glucose, respectively, due to the excellent peroxidase-like activity of Cu NPs/g-C₃N₄ originating from the synergistic effect of Cu NPs and g-C₃N₄. In this work, we utilized the easily forming complex ability of dicyandiamide and Cu²⁺ ions to form a homogeneous precursor solution, and then obtained the CuNPs/g-C₃N₄ product; such a method may have wide applications in novel composite nanomaterial preparation. The product may have promising applications in medical diagnostics and biotechnology fields.