Fluorescent Probes for Selective Probing Thiol-containing Amino Acids

Thiol-containing biomolecules, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH), play crucial roles in maintaining biological systems. For example, elevated levels of Hcy have been implicated as an independent risk factor for tumor invasion and metastasis. Being associated with a wide variety of cancer progressions, there is a significant interest in looking for the fluorescent detection of such thiol species (Cys, Hcy, and GSH) in cancer cells. Various thiol-specific probes have been developed on the basis of different strategies. This review focuses on recent contributions for the fluorescent or colorimetric sensors for thiol-containing amino acids, with special emphasis on the design and application of novel fluorophores for detecting thiol-containing amino acids with higher sensitivity.