Bis-cyclometalated Ir(III) Complex-Based Electrogenerated Chemiluminescence Sensor Array for Discriminating Three Biothiols

A simple and sensitive electrogenerated chemiluminescence (ECL) sensor array was developed for the discrimination of three biothiols, including homocysteine (Hcy), cysteine (Cys) and glutathione (GSH) using two bis-cyclometalated Ir(III) complexes as ECL probes. Two aldehyde groups bearing bis-cyclometalated Ir(III) complexes were selected as ECL probes, including [(bt)(2)Ir(phen-CHO)]PF6 (bt = 2-phenylbenzothiazole, phen-CHO = 1,10-phenanthroline-5-carboxaldehyde, probe 1) and [(ppy)(2)Ir(phen-CHO)]PF6 (ppy = 2-phenylpyridine, probe 2). A "signal on" ECL method was proposed for biothiols assay based on the increase in ECL intensity of two ECL probes by biothiols. Three biothiols can be detected with detection limits of 0.8, 0.7 and 0.8 mu M by probe 1 and 0.3, 0.4 and 0.5 mu M by probe 2 for Cys, Hcy and GSH, respectively. Two-element sensor array was assembled for the detection of three biothiols due to the different enhancement effects of biothiols on the ECL intensity of two ECL probes. The ECL sensor array combining with the principal component analysis was applied to discriminate three biothiols. This study demonstrates that the ECL sensor array using dual ECL reagents provides a promising way for the discrimination of multiple biothiols with good sensitivity and simpleness.