Enzyme-Responsive Bioprobes Based on the Mechanism of Aggregation-Induced Emission

Enzymes play an indispensable role in maintaining normal life activities. The abnormalities of content and activity in specific enzymes are usually associated with the occurrence and the development of major diseases. Correspondingly, fluorescent bioprobes with distinctive sensing mechanisms and different functionalities have attracted growing attention as convenient tools for optical probing and monitoring the activity of enzymes. Ideally and excitedly, the recently emerged luminogens with an aggregation-induced emission (AIE) feature could perfectly overcome the aggregation-caused quenching (ACQ) effect of conventional bioprobes. Based on the fantastic characteristics of AIE luminogens (AIEgens), specific enzyme bioprobes have been designed through integration with recognition units, demonstrating many advantages including low background interference, a high signal-to-noise ratio (SNR), and superior photostability. In this review, by presenting some typical examples, we summarize the working principle and structural design of specific AIEgen-based bioprobes that are triggered by enzymes and discuss their great potential in biomedical applications, with the aim to promote the future research of fluorescent bioprobes involving enzymes.