Harnessing aggregation-induced emission-active fluorescent probes to illuminate intracellular metal ions.

Metal ions are indispensable components in numerous physiological processes, and their homeostatic imbalance can lead to serious pathological disorders. Therefore, achieving accurate tracking and real-time monitoring of these ions within living systems is crucial for biological research and clinical diagnostics. Aggregation-induced emission luminogens (AIEgens), which exhibit enhanced fluorescence in the aggregated state due to the restriction of intramolecular motions, have become promising tools for metal ion sensing offering superior photostability, high signal-to-noise ratio, and excellent performance in aqueous media. This review systematically summarizes recent advances in the design and application of AIE-active fluorescent probes for detecting and imaging relevant metal ions (e.g., Cu2+, Hg2+, Zn2+) in live cells, and highlights how these probes bridge the gap between chemical sensing and intracellular bioimaging. Finally, we discuss the current challenges and prospects of AIE-based probes in metal ion biology, aiming to inspire further innovation in this burgeoning field.