A novel rhodamine-based dual-mode fluorogenic probe for sensitive determination of Hg²

Mercury ions (Hg²⁺) are highly toxic and persistent heavy metal pollutants that pose serious threats to environmental systems and human health. Therefore, developing sensitive and selective detection strategies for Hg²⁺is of great significance. In this study, a rhodamine-based dual-mode fluorescent probe (RB-HG) was developed utilizing dimethylthiocarbamate groups as recognition sites.Upon undergoing specific interaction with Hg²⁺, leading to the dissociation of the C-O bond and subsequently triggering an opening-ring reaction to form a ketone structure(RB-C=O), thereby activating the intramolecular charge transfer(ICT)process and generating both fluorescence and colorimetric signals,thereby activating both colorimetric and fluorescence dual-channel signals.In vitroexperiments demonstrate that RB-HG (5.0μM) exhibits high selectivity and sensitivity toward Hg²⁺. The limits of detection for the fluorescence and colorimetric detection modes are 1.16μM and 3.22μM, respectively. RB-HG was successfully applied to detect Hg²⁺in food samples with excellent recovery rates and to image exogenous Hg²⁺in living cells, highlighting its potential for food monitoring and bioimaging applications.