Near-Infrared Probes for Biothiols (Cysteine, Homocysteine, and Glutathione): A Comprehensive Review

Biothiols (cysteine, homocysteine, and glutathione) are an important class of compounds with a free thiol group. These biothiols plays an important role in several metabolic processes in living bodies when present in optimum concentration. Researchers have developed several probes for the detection and quantification of biothiols that can absorb in UV, visible, and near-infrared (NIR) regions of the electromagnetic spectrum. Among them, NIR organic probes have attracted significant attention due to their application in in vivo and in vitro imaging. In this review, we have summarized probes for these biothiols, which could work in the NIR region, and discussed their sensing mechanism and potential applications. Along with focusing on the pros and cons of the reported probes we have classified them according to the fluorophore used and summarized their photophysical and sensing properties (emission, response time, limit of detection).

Automated summary

Biothiols, such as cysteine, homocysteine, and glutathione, are important compounds with a free thiol group. They play a crucial role in metabolic processes when present in optimal concentrations. Researchers have developed various probes, including NIR organic probes, for the detection and quantification of biothiols, which have been widely used in in vivo and in vitro imaging. This review summarizes the NIR probes for biothiols, discusses their sensing mechanism and potential applications, and classifies them based on the fluorophore used, providing information on their photophysical and sensing properties.