Selective Hg²⁺ Detection Using an Aza-BODIPY-Derived NIR Fluorescence Sensor: Environmental and Biological Applications

Mercury contamination in natural environments poses severe threats to ecosystems and human health, emphasizing the urgent need for reliable Hg²⁺ detection methods. In this work, a novel near-infrared (NIR) fluorescent aza-BODIPY derivative (BT) was synthesized as a potential fluorescence sensor. BT exhibited dual colorimetric and "turn-on" NIR fluorometric responses toward Hg²⁺ in H₂O:EtOH (3:7 v/v), achieving a detection limit of 1.7 ppb. The sensor displayed high selectivity through rapid BT-Hg²⁺ complexation, with reversible sensing enabled by the addition of potassium iodide (KI). Practical applicability was demonstrated by quantifying Hg²⁺ in environmental water and fertilizer samples. BT-based paper test strips provided a specific colorimetric response for Hg²⁺, while bioimaging in human liver cancer cells revealed effective visualization with low cytotoxicity. Collectively, these findings establish BT as a versatile and reliable platform for Hg²⁺ detection, offering significant promise for environmental monitoring and sustainable health protection.