Selective and sensitive detection and detoxification of Pd²⁺ in living cells with a water-soluble fluorescent probe

Due to the cytotoxic potential of even low doses of Pd²⁺, the development of its detection and detoxification strategies is highly demanding. In this paper, we developed a water-soluble fluorescent probe IMQU-8 with a new scaffold for Pd²⁺ sensing. IMQU-8 can detect Pd²⁺ with high selectivity and sensitivity and has a good detection limit of 2.5 nM under physiological conditions. Its sensing mechanism has been revealed through job plot experiments and HRMS, FT-IR, ¹H NMR and DFT calculations, which demonstrated that the N atoms of the pyridyl group and imino group are crucial for Pd²⁺ sensing. Fluorescence lifetime assessment indicated that IMQU-8 and IMQU-8-Pd have almost identical fluorescence lifetimes, implying that IMQU-8 undergoes static quenching toward Pd²⁺. Additionally, IMQU-8 has been successfully applied to image Pd²⁺ in living cells. Since IMQU-8 and its coordinated complex IMQU-8-Pd exhibit low toxicity, IMQU-8 has been applied for the detoxification of Pd²⁺ in living cells.