Development of Next-Generation Fluorescent Turn-On Sensor to Simultaneously Detect and Detoxify Mercury in Living Samples

Strategies for simultaneous detection and detoxification of Hg^(2+) using a single sensor from biological and environmental samples are limited and have not been realized in living organisms so far. We report a highly selective, small molecule ‘turn-on’ fluorescent sensor, PYDMSA, based on the cationic dye, Pyronin Y (PY), and chelating agent, meso-2, 3-dimercaptosuccinic acid (DMSA) for the simultaneous detection and detoxification of inorganic mercury (Hg^(2+)). After Hg^(2+) detection, concomitant detoxification is carried out with sufficient efficacy in living samples which makes the sensor unique. PYDMSA exhibits high selectivity for Hg^(2+) over other competing metal ions with an experimental detection limit of ~300 pM in aqueous buffer solution. When PYDMSA reacts with Hg^(2+), the CS-C^9 bond in the sensor gets cleaved. This results in the ‘turn-on’ response of the fluorescence probe with a concomitant release of one equivalent of water-soluble Hg^(2+)-DMSA complex which leads to synchronous detoxifying effect. The sensor by itself is non-toxic to cells in culture and has been used to monitor the real-time uptake of Hg^(2+) in live cells and zebrafish larvae. Thus, PYDMSA is a unique sensor which can be used to detect and detoxify mercury at the same time in living samples.