Research progress of nanozymes in colorimetric biosensing: Classification, activity and application

Nanozymes, as a kind of nanomaterials with enzyme-like activity, are gradually becoming effective substitutes for natural enzymes because of their advantages such as regulated catalytic activity, flexible design, high stability and good biocompatibility. The excellent catalytic activity of nanozymes also makes them widely used in the construction of colorimetric biosensors. Colorimetric sensors have many advantages such as naked-eye visibility, easy operation, high sensitivity, and portability, etc. It has become a powerful and effective tool for immediate detection to construct novel colorimetric sensing strategies by combining nanozymes with colorimetric sensors. In this paper, the research progress of nanozymes and their applications in colorimetric biosensing are reviewed. Firstly, based on the different nanomaterials, nanozymes are introduced in a classification manner and their characteristics are described in detail. After that, this review focuses on the analysis of construction strategies of nanozymes with oxidase (OXD) activity, peroxidase (POD) activity, catalase (CAT) activity and superoxide dismutase (SOD) activity in colorimetric biosensors, and clearly explains the recent research progress of nanozymes in colorimetric detection. Finally, the challenges and future prospects of colorimetric biosensors based on nanozymes are discussed in order to provide useful references for researchers in related fields.