An Easily Synthesized Fluorescent Probe with Nanomolar Sensitive for Detection of Hg ²⁺ via a Reaction-Based Mechanism and Its Application in Tap Water, Fish, Shrimp, Soil Samples, and Living Cells

Mercury ion (Hg²⁺) is a ubiquitous heavy metal pollutant that poses health risks through its environmental transport and accumulation in living organisms. To address this, we designed and constructed a chemically reactive probe, BTS, capable of sensitively and selectively detecting Hg²⁺. The probe displayed excellent analytical performance, including high selectivity, a fast response time (120 s), and a low detection limit (3.9 nM). Mechanistic studies, utilizing ¹H NMR titration, HPLC, and HRMS, confirmed that, upon Hg²⁺ binding, the dithiane group of the probe is specifically transformed into an aldehyde moiety. BTS was successfully employed to detect Hg²⁺ in tap water, soil, fish, and shrimp samples, validating its practical utility. Additionally, BTS-based test strips offered a convenient method for visual Hg²⁺ detection under UV light, and the probe proved effective for fluorescence imaging in living cells. This research concept provides valuable insights into the investigation of the environmental behavior of heavy metal ions.