Application and mechanism of ratiometric fluorescent probes based on ESIPT and AIEE mechanisms for cyanide detection in biological systems.

Cyanide, as a highly toxic pollutant, is prone to remain in food systems such as white spirits during the processing of cyanogenic plants, posing a serious threat to human health. To address the limitations of conventional detection methods such as complexity, high cost, and insufficient sensitivity, this study developed a ratiometric fluorescent probe HTBC based on the dual mechanisms of excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission enhancement (AIEE). The probe exhibits dual emission peaks at 470 nm and 534 nm, and its hydroxyl/multi-benzene ring structure can enhance the signal-to-noise ratio through the ESIPT effect. When CN- triggers deprotonation, the intramolecular hydrogen bond breaks, resulting in a significant blue shift of fluorescence, achieving highly selective and sensitive detection of cyanide. Further combined with the developed intelligent computer color recognition system, it was successfully applied to cassava white spirits and Caenorhabditis elegans models, enabling visual analysis of cyanide concentration: it was found that cyanide exceeded the standard in the early stage of white spirit fermentation and stabilized at 7 mg/L in the final stage, highlighting the importance of process control. This study provides an efficient strategy integrating rapid response, intelligent visualization, and on-site analysis for food safety and environmental pollution monitoring.