Simultaneous quantification of multiple endogenous biothiols in cancer cells based on a multi-signal fluorescent probe

Although a large number of fluorescent probes have been developed, the simultaneous quantitative analysis of intracellular thiols is still difficult due to the spectral overlap and the complexity of the intracellular environment. In this study, a multi-signal fluorescent probe was employed for the simultaneous quantification of intracellular glutathione (GSH), cysteine (Cys) and homocysteine (Hcy). As the feature variables of the target components, the Tchebichef image moments (TMs) calculated from the grayscale images of the 3D fluorescence spectra were used to establish the quantitative linear models by stepwise regression. The intra-day and inter-day precisions of the proposed method were less than 5.6% and 8.7%, respectively. The recoveries ranged from 97.0% to 105.9%. In addition, the proposed approach was applied to the simultaneous quantitative determination of Cys, GSH and Hcy in the MCF-10A cell (a type of normal cell) and MDA-MB-231 cancer cell. The obtained results indicated that the concentrations of the three thiols in the cancer cell were higher than those in the normal cell. This study not only provides an effective approach for the quantification of multi-target bio-molecules in complicated intracellular environments, but also further extends the applications of multi-signal fluorescent probes, which will promote the design of new multi-signal fluorescent probes.