Rhodamine‐Functionalized Nanosensor for Multimodal, Ultrasensitive, and Stable Detection of Toxic Mercury Ions

ABSTRACT Nanoprobes are increasingly investigated for the ultrasensitive detection and monitoring of heavy metal pollutants. Mercury (II), a significant global threat to food safety and public health, has prompted the development of numerous probes. However, existing systems often fail to achieve nanomolar‐level detection in aqueous environments. To address this critical challenge, we developed a self‐assembled amphiphilic dual rhodamine B nanoprobe ( DR ) that forms stable nanospheres with an average size of 247.97 nm. This innovative nanosensor exhibits exceptional selectivity and dual‐mode responsiveness in aqueous solution, characterized by a rapid 12‐s “turn‐on” fluorescence response accompanied by visible colorimetric changes. The nanosensor achieves an ultralow detection limit of 0.19 n m for Hg ²⁺ , outperforming most homologous detection systems. Its practical utility was validated across three complementary platforms: smartphone‐based RGB analysis, hydrogel sensors, and paper‐based test strips. The nanoprobe demonstrates robust performance in real‐world applications, yielding recovery rates between 97.0% and 107.5% across diverse sample types, including agricultural products, soil, aquatic systems, and biological specimens (zebrafish larvae, plant tissues). By integrating cost‐effective one‐pot synthesis with ultra‐sensitive detection and multi‐modal platforms, this nanosensor offers a promising and effective solution for monitoring Hg ²⁺ levels in diverse environmental and food safety scenarios.