Enhanced peroxidase-like activity of AuNPs loaded graphitic carbon nitride nanosheets for colorimetric biosensing

Nanozymes have emerged as promising alternatives to overcome the high cost and low stability issues of natural enzymes . Particularly, those with peroxidase-like activities have been extensively studied to construct versatile biosensors . In this article, we demonstrate that the modification of the graphitic carbon nitride nanosheets (g-C 3 N 4 nanosheets) by plasmonic gold nanoparticles (AuNPs) greatly enhances its catalytic performance as peroxidase mimetic. In the presence of H 2 O 2 , the [email protected] 3 N 4 nanosheets can catalyze the redox reaction of 3,3′,5,5′- tetramethylbenzidine (TMB) to produce a blue color. Based on the observation, a colorimetric sensing method for glucose is further developed with the assistance of glucose oxidase (GOx). The linear range for glucose is from 5 to 100 μmol L −1  (R 2  = 0.9967) and the limit of detection (LOD) is 1.2 μmol L −1 . The LOD can be further lowered down to 0.75 μmol L −1  by using H 2 SO 4 as termination agent and measuring the absorbance of the yellow product at λ = 451 nm. Moreover, the practical usefulness of [email protected] 3 N 4 nanosheets as a peroxidase nanozyme for glucose determination in human serum and urine is also demonstrated.