Sensing of zinc ion and sulfide by a highly practical and water-soluble fluorescence sensor: applications in test kits and zebrafish

Abstract

A novel practical fluorescent sensor AMPQ (2-((3-morpholinopropyl)amino)-N-(quinolin-8-yl)acetamide)) was designed and synthesized. In bis-tris buffer, AMPQ displayed a highly practical and selective fluorescence recognition to Zn2+, clearly discriminating it from Cd2+ and other cations. Moreover, AMPQ-Zn2+ complex exhibited fluorescence “turn-off” response to S2- with exceptional selectivity via S2--induced Zn2+ displacement approach. Detection limits (0.29 and 2.39 μM) of AMPQ for Zn2+ and S2- were highly lower than WHO guidelines (76.0 and 14.7 μM), respectively. Importantly, sensor AMPQ could be applied to various practical applications such as real water samples and test kits. In particular, AMPQ could monitor both Zn2+ and S2- in live zebrafish, with a 0.74 μM detection limit to Zn2+, which is the lowest among sensors previously reported for relay detection of Zn2+ and S2-. Sensing processes of AMPQ to Zn2+ and S2- were illuminated by UV-vis and fluorescence spectroscopy, Job plot, ESI-MS, 1H NMR titrations, and calculations.