A novel bisphenol A-derived chemosensor for ultrasensitive sensing of Al3+ and Zn2+: applications in food, hydrogels and cellular imaging.

A Schiff base fluorescent probe (BYO) was designed and synthesized from bisphenol A. BYO fluorescent "turn-on" sensor can rapidly and simultaneously measure Al3+/Zn2+ with superior sensitivity and selectivity. Other than that, BYO exhibits enhanced fluorescence in the presence of Al3+ and Zn2+ across a wide pH range, which is resistant to interference. The detection limits were extremely low, reaching Al3+ at 9.4 × 10-9 M and Zn2+ at 4.6 × 10-8 M. The binding coefficients were calculated 8.76 × 1010 M-2 for Al3+ and 4.16 × 109 M-2 for Zn2+. Data from Job's, 1H NMR, FTIR, LC-MS, and DFT support a synergistic mechanism involving excited-state intramolecular proton transfer (ESIPT) and photoinduced electron transfer (PET). Furthermore, the BYO probe was also successfully integrated into the hydrogel to visualize and monitor the dynamic distribution and concentration changes of Al3+ and Zn2+. Moreover, characterized by high transmembrane efficiency, the BYO probe facilitates in situ detection of Al3+ and Zn2+ within living cell via fluorescence bioimaging. This work enhances the biocompatibility of fluorescent probes and expands the potential of the probes for applications in biology and smart response materials.