Eosin Y-Derived Fluorescent Sensors: Selective Hg²⁺ Detection, and Targeted Biomedical Applications

Abstract

Two Eosin Y–based chemosensors (EY-SO: λem=534 nm) and (EY-SM: λem=551 nm) are synthesized for the selective, sensitive, and recyclable fluorescence “turn-on” detection of aquated Hg²⁺ ions. The quantum yield and fluorescence lifetime of the sensors were measured before and after analyte detection. Appreciable limits of detection (LOD: 6.012±0.57 and 5.929±0.09 nM, respectively) are observed. Optimal sensing occurs in neutral to slightly basic pH aqueous solutions. A selective Hg²⁺ detection mechanism is proposed based on experimental evidence. For the first time, the anticancer activities of Eosin Y-based chemosensors (EY-SO and EY-SM) and their Hg²⁺ complexes (EY-MO and EY-MM) are studied. The anticancer activities of the complexes are significantly higher than those of their respective organic precursor or mercuric ions. The complexes are more effective against certain cancer cell lines relative to healthy cells. The IC50 of EY-MM is 3.85±0.306 µM against MDA-MB-231 and >50 µM against HEK-293 under similar experimental conditions. Various assays, including ROS generation, live/dead fluorescence imaging, and Annexin V-FITC/PI dual-staining, confirmed the underlying cell death pathways. Overall, we describe a facile approach to convert toxic Hg²⁺ species into two potent anticancer agents (EY-MO and EY-MM) for biomedical applications using two biocompatible chemosensors (EY-SO and EY-SM).