Development and applications of two colorimetric and fluorescent indicators for Hg 2+ detection.

Two rhodamine-active probes RBAI (Rhodamine B-di-Aminobenzene-phenyl Isothiocyanate) and RGAI (Rhodamine 6G-di-Aminobenzene-phenyl Isothiocyanate) were designed, synthesized and characterized. The probes were developed as fluorescent and colorimetric chemodosimeters in ethanol-water solution with a broad pH span (5-10) and high selectivity toward Hg ²⁺ but no significant response toward other common competitive cations. The Hg ²⁺ -promoted ring opening of spirolactam of the rhodamine moiety induced cyclic guanylation of the thiourea moiety, which resulted in the dual chromo- and fluorogenic observation (off-on). Cytotoxicity and bioimaging studies by L929 living cells and living mice indicated that the probes were negligible cytotoxicity, cell permeable and suitable for detecting Hg ²⁺ in biological environments. Moreover, the new probes not only displayed excellent abilities for the successful detection of Hg ²⁺ in L929 living cells and living mice but also able to detect Hg ²⁺ by adsorbing on solid surfaces and quantitative detection of Hg ²⁺ in real water samples with good recovery (more than 90%), indicating that they have promising prospect for application for Hg ²⁺ sensing in environmental and biological sciences.
(Copyright © 2017. Published by Elsevier Inc.)