Graphitic carbon nitride with Cu2+ and triazole group co-doping for enhanced peroxidase-like activity and its application for glutathione detection

Abstract

Nanozymes have attracted great interest in the field of biotechnology, (bio)sensing, and environmental monitoring. Herein, a co-doping strategy is proposed to enhance the peroxidase-like activity of graphitic carbon nitride (g-C₃N₄). Cu²⁺ and triazole group co-doped graphitic carbon nitride (g-C₃N₅-Cu²⁺) was derived from thermal polymerization of 3-amino-1,2,4-triazole and then coordination with Cu²⁺. g-C₃N₅-Cu²⁺ nanosheets (NSs) could catalyze the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂ under neutral conditions, yielding 10.9-fold better catalytic activity than g-C₃N₄ NSs. Reactive oxygen species scavenging experiments indicated that ˙OH played a crucial role during the catalytic process. When glutathione (GSH) was introduced, the absorbance of the system decreased because of the reduction of the oxidation product of TMB by GSH. The colorimetric method demonstrated a sensitive response for GSH with a linear range of 0.8–33.3 μmol L⁻¹ and a limit of detection of 0.3 μmol L⁻¹. The sensitivity is higher than most other peroxidase mimetic-based colorimetric methods for GSH. Finally, the feasibility for the detection of GSH in HeLa cells was demonstrated.