Recent advances in the development of responsive probes for selective detection of cysteine

Cysteine (Cys), one of three endogenous biothiols, is involved in a variety of biological processes, such as protein and peptide biosynthesis, enzyme active sites and cofactors, and redox balance regulations. An imbalance in the measured levels of Cys, against normative levels of Cys, is implicated in a series of human diseases, so that Cys has been recognized as one of the most important biomarkers in early diagnosis and treatment as well as the monitoring of the stage of diseases. Rapid and accurate quantification of Cys within complex biological systems enables in the advance of future personalized diagnostics and therapies. In the past few years, many Cys-responsive luminescence probes have been developed for the quantitative detection of Cys; studies where the full prepared probe is validifed by investigations in vitro and in vivo. In this review, advances in the development of Cys-responsive luminescence probes, including molecular probes and nanoprobes, are included and discussed in sections corresponding to their response mechanisms. The structure of molecular probes are included; performances of various bioanalytical probes in Cys detection are compared in aspects of excitation/emission wavelengths, detection limits and dynamic ranges, as well as experimental conditions for practical applications. Current challenges and future research directions for designing and preparing new Cys-selective probes are proposed.