Hemin-porous g-C 3 N 4 hybrid nanosheets as an efficient peroxidase mimic for colorimetric and visual determination of glucose

A method is described for colorimetric determination of glucose by using hemin-porous graphitic carbon nitride (g-C 3 N 4 ) hybrid nanosheets as a peroxidase mimic. The porous g-C 3 N 4 nanosheets were prepared by a combination of one-pot self-polymerization, pyrolysis and liquid-phase exfoliation. The hemin-porous g-C 3 N 4 hybrid nanosheets were prepared via in-situ deposition. It is shown that the hybrid composite has improved dispersibility, stability, and peroxidase-mimicking activity in the 3,3′,5,5′–tetramethylbenzidine (TMB)/H 2 O 2 system. This is deemed to be the result of the synergistic effect of hemin and porous g-C 3 N 4 nanosheets. Based on these advantages of the nanosheets, a simple, low-cost, sensitive and selective colorimetric method was established for the determination of glucose at pH values around 7. Best performed at a wavelength of 652 nm, the assay has a linear response in the 10.0 μM to 500 μM glucose concentration range (R 2 = 0.9942) and a 1.94 μM limit of detection. This method was successfully applied to the determination of glucose in (spiked) human serum samples. In our perception, the hybrid is a robust peroxidase mimic for use in POx-based assays as needed in medical diagnosis and environmental analysis. Graphical abstract Schematic presentation of the process of hemin-porous g-C 3 N 4 hybrid nanosheets catalyzing the oxidation of peroxidase chromogenic substrate tetramethylbenzidine (TMB) in the presence of H 2 O 2 . The material was applied in colorimetric and visual determination of H 2 O 2 and glucose.