Rapid and selective detection of biothiols by novel ruthenium(II) complex-based phosphorescence probes.

Considering the excellent photochemical properties of ruthenium(II) complexes, two new ruthenium(II) complexes, RuL1-DNBS and RuL2-DNBS, have been developed as phosphorescence probes for detection of biothiols in 100:1 (v/v) Hepes buffer (20 mM, pH = 7.2)/CH3CN solution. The response rate was highly improved of these two probes toward biothiols because the steric interactions between 1H-imidazo [4, 5-f] [1,10] phenanthroline group and ortho-2, 4-dinitrobenzensulfonate resulted in a relatively rapid thiol-induced SNAr substitution reaction. RuL1-DNBS and RuL2-DNBS were weakly phosphorescent owing to the effectual photoinduced electron transfer from ruthenium(II) luminophore to the sensing group, 2,4-dinitrobenzenesulfonyl. After reacting with biothiols, the 2,4-dinitrobenzenesulfonyl group of RuL1-DNBS and RuL2-DNBS were cleavaged and the RuL1 and RuL2 were obtained. Meanwhile, the phosphorescence were “turn-on”. Both of these two probes can detect biothiols sensitively and selectively under physiological conditions with submicromolar detection limits. Furthermore, application of RuL2-DNBS for detecting of intracellular biothiols has been successfully performed in living Glioma cells.