Highly-efficient peroxidase-like catalytic activity of graphene dots for biosensing

In recent years, considerable efforts have been devoted to the construction of efficient enzyme mimetics, which have significant advantages of simple synthesis, good stability and design flexibility. In this paper, we described that graphene dots (GDs) possess highly-efficient peroxidase-like catalytic activity, and its activity is much higher than graphene oxide (GO) with large size. They can catalyze the oxidation of peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue product, which can be used for H2O2 detection by measuring the absorbance change. This catalytic reaction can be also used for other analyte detection by monitoring the generation or consumption of H2O2, such as glucose and reduced glutathione (GSH). The GDs-based system permits detection of as low as 10 nM H2O2, which is much lower than that of other nanomaterials-catalyzed methods. Meanwhile, the detection limit of this system is 0.5 μM for glucose and 0.5 μM for GSH, respectively. Furthermore, the proposed system also shows high selectivity and is capable of sensing in complicated biological samples such as cell lysate. Due to their high catalytic activity, high diffusion and excellent biocompatibility, GDs can be expected to be applied in various fields, such as biotechnology, medical diagnostics and environmental monitoring.