In modern biology, hydrogen polysulfides (H₂S_n, n > 1) are members of reactive sulfur species (RSS), with anti-oxidation, cell protection and redox signals in tissues and organs. Therefore, it is crucial to develop a method to monitor the changes of H₂S_n level in organisms. We designed and synthesized a ratiometric fluorescent probe for highly selective detection of H₂S_n based on the fluorescence resonance energy transfer (FRET) process. In this work, a coumarin derivative was chosen as an energy donor, a rhodol derivative was used as an energy acceptor and a 2-fluoro-5-nitrobenzoate group was applied as a recognition unit for H₂S_n. In the absence of H₂S_n, the rhodol receptor existed in the non-fluorescent spirolactone state and FRET process was disabled. In the presence of H₂S_n, the closed spirolactone form was converted to a conjugated fluorescent xanthenes form to invoke the occurrence of FRET which resulted in a 77 nm red-shift of fluorescence emission from 460 nm to 537 nm. The ratio value of the fluorescence intensity between 537 nm and 460 nm (I_537nm/I_460nm) of the probe exhibited a good linear relationship toward H₂S_n in the range of 3.0 × 10⁻⁶–1.0 × 10⁻⁴ mol·L⁻¹, and the detection limit was estimated to be 8.0 × 10⁻⁷ mol·L⁻¹. In addition, the ratiometric fluorescent probe showed high specificity for H₂S_n over other biologically related species. Moreover, the probe displayed little cell toxicity and had been successfully used to the confocal imaging of H₂S_n in HepG2 cells by dual emission channels.

在现代生物学中，多硫化氢（H ₂ S _n，n  > 1）是反应性硫物质（RSS）的成员，在组织和器官中具有抗氧化，细胞保护和氧化还原信号。因此，开发一种监测生物中H ₂ S _n水平变化的方法至关重要。我们基于荧光共振能量转移（FRET）过程设计并合成了用于高选择性检测H ₂ S _n的比例荧光探针。在这项工作中，香豆素衍生物被选作能量供体，Rhodol衍生物被用作能量受体，2-氟-5-硝基苯甲酸酯基被用作H ₂ S的识别单元_n。在没有H ₂ S _n的情况下，Rhodol受体以非荧光螺内酯状态存在，并且FRET过程被禁用。在存在H ₂ S _{n的情况下}，将封闭的螺内酯形式转换为共轭的荧光黄嘌呤形式，以引起FRET的出现，从而导致荧光发射从460 nm到537 nm发生77 nm的红移。探针的537 nm和460 nm之间的荧光强度的比值（I _537nm / I _460nm）在3.0×10 ^-6 –1.0×10 ^-4  mol·的范围内表现出与H ₂ S _n的良好线性关系。 L ^-1和检测极限估计为8.0×10 ^-7 莫尔^-1。此外，比例荧光探针对H ₂ S _n的特异性高于其他生物学相关物种。此外，该探针显示出极小的细胞毒性，并已成功用于双发射通道对HepG2细胞中H ₂ S _n进行共聚焦成像。