Recent advances in enzyme-activated NIR fluorescent probes for biological applications

Enzymes and their regulations are employed as indicators for various diseases, including cancer. To directly analyze the activity of the enzymes within a biological system, enzyme-activated near-infrared (NIR) fluorescent probes are being continuously developed. These probes enable clear imaging of enzyme activity in real time with high spatiotemporal resolution, while preserving their unique advantages such as high sensitivity, reduced autofluorescence, and low light scattering. Enzyme expression levels can also be investigated by evaluating the emission intensity. Owing to these strengths, enzyme-activated NIR fluorescent probes have been applied in various clinical areas such as biomedical imaging, quantitative analysis, and surgery. Therefore, the development of NIR fluorescent probes that could be specifically activated by disease-related enzymes is a crucial task. In this review, we introduce several enzymes associated with disorders and summarize the relevant activated NIR fluorescent probes reported from 2020 to 2023.