Colorimetric and Fluorescence Dual-Mode Biosensors Based on Peroxidase-Like Activity of the Co3O4 Nanosheets

The mimic enzyme has become a research hotspot in recent years because of its advantages of high stability, convenient preparation, and low price. In this article, Co3O4 nanosheets synthesized by a simple hydrothermal method possess the characteristics of a peroxidase-like activity. The results demonstrated that 3,3 ',5,5 '-Tetramethylbenzidine (TMB) could be oxidized by H2O2 to produce a typical blue product (oxTMB) which has a strong absorption at 650 nm wavelength with the help of the Co3O4 nanosheets. Thus, a simple and sensitive colorimetric detection method for H2O2 was established with a good linear relationship (2-200 mu M) and a low limit of detection (0.4 mu M). Meanwhile, the colorimetric product can effectively quench the fluorescence emitted by Ru(bpy)(3)(2+). Therefore, a colorimetric and fluorescence dual detection mode photochemical sensor for H2O2 detection is constructed based on the principle of the inner filter effect (IFE) between the colorimetric product (oxTMB) and Ru(bpy)(3)(2+). It can effectively avoid the false positive problem of a single detection mode. In the presence of glucose oxidase, glucose can be catalyzed to produce gluconic acid and H2O2; therefore, the sensor can also be used for the determination of glucose with a good linear relationship (0.02-2 mu M) and a low limit of detection (5 nM). Experimental results showed that the sensor has a high sensitivity and strong anti-interference ability which can be used for the detection of actual samples.

Automated summary

Mimic enzymes have gained attention in recent years due to their high stability, convenient preparation, and low price. This article presents the synthesis of Co3O4 nanosheets with peroxidase-like activity through a simple hydrothermal method. A colorimetric and fluorescence dual detection mode photochemical sensor based on the Co3O4 nanosheets is established for the detection of H2O2 and glucose. The sensor exhibits high sensitivity and strong anti-interference ability.