A rhodamine-based fluorescent probe bearing 8-hydroxyquinoline group for the highly selective detection of Hg2+ and its practical application in cell imaging

Abstract

A highly selective and sensitive fluorescent probe, RHOQ, was designed for the detection of Hg²⁺ by incorporating an 8-hydroxyquinoline moiety onto a rhodamine molecular platform with a suitable linker. In MeOH–Tris (20 mM, pH = 7.4, 1 : 9, v/v) buffer solution, RHOQ exhibited 550-fold fluorescence enhancement at 594 nm upon addition of Hg²⁺, with a fast response and a low detection limit (9.67 × 10⁻⁸ M). The 1 : 1 binding mode of RHOQ with Hg²⁺ was established using Job's plot, UV-Vis, and fluorescence spectroscopic titration methods. Furthermore, RHOQ was successfully applied for the detection of Hg²⁺ in living cells with good membrane permeability.