A colorimetric and fluorescent probe for rapid detection of glutathione and its application to tissue specific bio-imaging in living cells and zebrafish

Owing to the many physiological functions of glutathione, fluorescent sensing systems that selectively and sensitively detect this biothiol in biological systems are in great demand. In this study, we developed a rhodamine-based probe to detect glutathione. The probe, which contains an α-bromoamide reactive center, responds rapidly and highly selectively to glutathione in both a colorimetric and “off/on” fluorescence manner. Upon addition of glutathione to a solution of the probe, up to an 80-fold enhancement in the intensity of fluorescence at 579 nm takes place, which can be visually observed by using a hand-held UV lamp (365 nm). Moreover, following addition of glutathione to the solution of the probe undergoes a color change from colorless to pink in association with the development of an absorption band at 560 nm. Consequently, glutathione detection can be made using “naked-eyes”. The results of studies aimed at exploring the cell permeability and intracellular GSH detection ability of the probe show that the probe can be utilized to sense endogenous and exogenous glutathione in HeLa cells. Moreover, the probe can be utilized to interrogate the oxidation states of glutathione, which are crucial to the maintenance of intracellular redox balances. Either addition of hydrogen peroxide or a lipopolysaccharide to solutions containing the probe and glutathione results in a remarkable decrease in the intensity of fluorescence due to their metabolism is in conjunction with glutathione oxidation. More interestingly, the probe can be used to detect glutathione in zebrafish with a high specificity for olfactory pit tissue.