Water‐Soluble BODIPY Fluorescent Sensors: Molecular Design, Sensing Mechanisms, and Applications

Fluorescent sensors are powerful tools for the sensitive and selective detection of chemical and biological analytes. Still, their practical applications are often limited by poor water solubility, aggregation, and inadequate aqueous compatibility. Boron‐dipyrromethene (BODIPY) dyes are particularly attractive fluorophores because of their high molar absorptivity, intense emission, excellent photostability, and tunable photophysical properties; however, their intrinsic hydrophobicity limits their use in aqueous media. Herein, we review recent advances in water‐soluble BODIPY‐based fluorescent sensors, focusing on molecular design and water‐solubilization strategies, sensing mechanisms, and applications for detecting metal ions, reactive species, gasotransmitters, biomolecules, and environmental analytes. This review discusses relationships among molecular structure, aqueous solubility, photophysical properties, and sensing performance, with particular attention to intrinsically water‐soluble probes and supported systems. The review also highlights current challenges and future opportunities, providing useful design principles for developing next‐generation BODIPY‐based fluorescent probes for sensing and imaging in aqueous and biological environments.