Hydrogen sulfide (H₂S) is not only a well-established toxic gas but also an important small molecule bioregulator in all kingdoms of life. In contemporary biology, H₂S is often classified as a “gasotransmitter,” meaning that it is an endogenously produced membrane permeable gas that carries out essential cellular processes. Fluorescent probes for H₂S and related reactive sulfur species (RSS) detection provide an important cornerstone for investigating the multifaceted roles of these important small molecules in complex biological systems. A now common approach to develop such tools is to develop “activity-based probes” that couple a specific H₂S-mediated chemical reaction to a fluorescent output. This Review covers the different types of such probes and also highlights the chemical mechanisms by which each probe type is activated by specific RSS. Common examples include reduction of oxidized nitrogen motifs, disulfide exchange, electrophilic reactions, metal precipitation, and metal coordination. In addition, we also outline complementary activity-based probes for imaging reductant-labile and sulfane sulfur species, including persulfides and polysulfides. For probes highlighted in this Review, we focus on small molecule systems with demonstrated compatibility in cellular systems or related applications. Building from breadth of reported activity-based strategies and application, we also highlight key unmet challenges and future opportunities for advancing activity-based probes for H₂S and related RSS.

中文翻译：

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用于硫化氢和相关活性硫物质的活性荧光探针

硫化氢（H ₂ S）不仅是一种公认​​的有毒气体，而且还是所有生命领域中重要的小分子生物调节剂。在当代生物学中，H ₂ S 通常被归类为“气体递质”，这意味着它是一种内源产生的膜渗透气体，可执行重要的细胞过程。用于 H ₂ S 和相关活性硫 (RSS) 检测的荧光探针为研究这些重要小分子在复杂生物系统中的多方面作用提供了重要的基石。目前开发此类工具的常见方法是开发“基于活性的探针”，将特定的 H ₂ S 介导的化学反应与荧光输出耦合。本综述涵盖了此类探针的不同类型，还重点介绍了特定 RSS 激活每种探针类型的化学机制。常见的例子包括氧化氮基序的还原、二硫键交换、亲电反应、金属沉淀和金属配位。此外，我们还概述了基于活性的互补探针，用于对还原剂不稳定和硫烷硫物种（包括过硫化物和多硫化物）进行成像。对于本综述中强调的探针，我们重点关注在细胞系统或相关应用中具有兼容性的小分子系统。基于已报道的基于活动的策略和应用的广度，我们还强调了推进 H ₂ S 和相关 RSS 的基于活动的探测的关键未解决挑战和未来机遇。