Construction of ICT-based fluorescence probes for the imaging of biothios

• This review summarizes the ICT-based fluorescence probes for the detection of biothiols for the first time. • This review summarizes the luminescence mechanisms of fluorescent probes for biothiols. • This review summarizes the structural classification of ICT-based probes. • This review summarizes recent advancements in ICT-based fluorescence probes for the imaging of biothiols. Biothiols are small molecules that play crucial physiological roles in various pathophysiological processes. However, their structural similarities and activities present significant challenges for selective detection. Fluorescent probes have garnered considerable attention for biothiol detection due to convenience and accuracy. Intramolecular charge transfer (ICT) is one of the primary strategies employed in the design of fluorescent probes . In comparison to other luminescent mechanisms, ICT-based probes possess the unique capability to simultaneously modify fluorescence emission intensity through enhancement (turn-on), quenching (turn-off), and ratiometric changes, while also altering the emission wavelength. This multifaceted control offers significant advantages. More importantly, when ICT is combined with other fluorescence mechanisms, such as photoinduced electron transfer (PET), Förster resonance energy transfer (FRET), and aggregation-induced emission (AIE), it facilitates the development of novel fluorescent probes with dual fluorescence reaction mechanisms and multi-fluorescence signal channel detection, thereby enhancing selectivity and sensitivity. Nevertheless, a systematic review of ICT-based fluorescent probes specifically for biothiol imaging is currently lacking. Therefore, summarizing the latest advancements in biothiol ICT-based fluorescence probes is both significant and urgent. Given the substantial number of ICT-based fluorescence probes reported, this discussion will be limited to those published within the past decade, specifically from 2013 to 2024. This article emphasizes the fundamental characteristics of biothiol ICT probes, detailing design principles, photophysical processes, sensing mechanisms, performance metrics, and biological applications. We categorize fluorescent probes based on the fluorophores employed in biothiol ICT probes, including naphthalimide, hemicyanine, nitrobenzoxadiazole, and dicyanoisophorone. This review aims to provide researchers with a comprehensive summary that inspires the design of new probes and advances the simultaneous detection of biothiols using ICT probes.