A Highly Sensitive Quinoline-Containing Rhodamine B Thiohydrazide Based Fluorescent Probe for Hg2+ in Aqueous Solution and Living Cells

Quinoline-appended rhodamine B thiohydrazide based fluorescent probe was designed and applied in fluorescent detections of mercury ions in both aqueous solution and living cells. The signal change of the probe is based on a specific metal ion induced reversible ring-opening mechanism of a rhodamine B thiohydrazide. The probe exhibits a dynamic response concentration range for Hg²⁺ from 1.0 × 10^?8 to 1.0 × 10^?5 M with a detection limit of 8.5 × 10^?9 M. The fluorescent probe is pH independent in medium condition and exhibits high selectivity over other common metal ions.