A Schiff base probe for competitively sensing Cu2+ and cysteine through hydrolysis, complexation, and cyclization

The form of a single response to a single target analyte limits the development of fluorescent probes . Here, a probe (HBTA) based on HBT (2-(2-Hydroxyphenyl)-benzothiazole) was synthesized to achieve a concept about nested probe, completing continuous detections. HBTA through low concentration Cu 2+ gives birth to a new probe (HBT-CHO) that can detect Cu 2+ by complexation and Cys by cyclization (HBT-Cys). These processes are accompanied by different fluorescent signal changes and can quantitatively detect Cys and Cu 2+ . Furthermore, HBT-CHO, HBT-Cys, and Cys can bind Cu 2+ , so competitive fluorescent response of Cu 2+ can take place through alternate addition of Cu 2+ and Cys. At this stage, the response becomes too complex to accurately quantify, but it is still dependable to predict changes in the content of the mixture system through competitive fluorescent changes. In summary, it is because of the existence of the nested pattern that HBTA completes multiple forms of responses to Cu 2+ and Cys.