AIE-Active Fluorescence "Turn-on" Bioprobes Mediated by Intramolecular Hydrogen-Bonding for Sensitive Detection of...

Hydrogen sulfide (H₂S) is a newly-recognized gaseous signaling molecule and participates in a range of physiological and pathological processes. In this work, based on a molecular switch coupling an imine group with an adjacent H-bond, we designed "turn-on" aggregation-induced emission (AIE)-active fluorescent probes for H₂S detection, designated as TSI series. To evaluate the substituents and electron effects on the molecular switch as well as H₂S response, four TSI compounds bearing different substituents (HTSI, DFTSI, DPTSI, and DOTSI) were synthesized and compared in the performance of H₂S sensing. Among all the probes, DPTSI achieves the best sensing performance toward H₂S (> tenfold fluorescence enhancement). Building on these findings, a rational design strategy involving H-bond protection/deprotection and electron-donating group modifications can be employed for developing other probes based on the TSI platform. In further glioblastoma cell imaging assessments, DPTSI effectively lighted up glioblastoma cells with high contrast due to their elevated H₂S levels, suggesting its potential as a practical tool for biological H₂S sensing and glioma cell mapping in vivo.