A highly selective and sensitive determination of Hg²⁺ in water samples with bioimaging applications in living cells using a fluorogenic pyrene-amino mercapto thiadiazole (PYAMT) probe is described. The probe PYAMT exhibited three absorption peaks at 333, 348 and 394 nm and emission maxima at 378, 388 and 397 nm (λ_ex = 348 nm). It showed significant fluorescent quenching (96%) with I/I₀ = 0.051 upon the addition of 2.5 μM Hg²⁺ ion in CH₃CN:H₂O (1:1, v/v; pH 7.2), whereas its fluorescence remained unaltered in the presence of other metal ions. The quenching phenomenon is attributed to the heavy atom effect of Hg²⁺ ion followed by electron transfer. The fluorescence intensity decreased linearly against a wide range from 100 nM to 2.5 μM Hg²⁺ (R² = 0.9937) with a limit of detection as low as 0.35 nM (S/N = 3). The binding stoichiometry ratio of PYAMT-Hg²⁺ is proved to be 1:1 by fluorescence and DFT measurements. The sensor possesses high association constant with Hg²⁺ ion in the order of 9.08 × 10⁵ M⁻¹ and it is also capable of reversibly detecting cysteine with OFF-ON mechanism. Finally, the proposed method is successfully applied to selectively detect Hg²⁺ ion in real water samples and bioimaging studies in live cells.

中文翻译：

---

基于pyr-氨基巯基噻二唑单元的荧光汞离子传感器

描述了使用荧光pyr-氨基巯基噻二唑（PYAMT）探针对活细胞进行生物成像应用的水样品中Hg ^2+的高选择性和灵敏测定方法。探针PYAMT在333、348和394 nm处表现出三个吸收峰，在378、388和397 nm处表现出发射最大值（_λex  = 348 nm）。在CH ₃ CN：H ₂ O（1：1，v / v; pH 7.2）中 加入2.5μMHg ²⁺离子后，它显示出显着的荧光猝灭（96％），I / I ₀ = 0.051在其他金属离子的存在下保持不变。猝灭现象归因于Hg ²⁺的重原子效应离子，然后进行电子转移。荧光强度在从100 nM到 2.5μMHg ²⁺的宽范围内线性下降（R ² = 0.9937），检出限低至0.35 nM（S / N = 3）。通过荧光和DFT测量证明，PYAMT-Hg ²⁺的结合化学计量比为1：1。该传感器与Hg ²⁺离子的结合常数高，为9.08×10 ⁵  M ^-1，并且还可以通过OFF-ON机制可逆地检测半胱氨酸。最终，该方法成功应用于选择性检测真实水样中的Hg ²⁺离子和活细胞的生物成像研究。