Sensitive detection of carcinoembryonic antigen based on a low-potential-triggered electrochemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with oxalate as coreactant

Abstract

Recently, tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) has been widely used in electrochemiluminescence (ECL) biosensors. However, its ECL has to be triggered at high positive or negative voltage, leading to a series of undesired side effects containing electrical damage toward biomolecules and hydrogen/oxygen evolution reaction. In this work, a new low-potential-triggered Ru(bpy)32+ ECL system was reported using oxalate as coreactant with the aid of platinum nanoparticles (Pt NPs) electrodeposited on the surface of the graphene-ionic liquid composite. When cyclic scanning in a potential range from 0.3 to −0.2 V, the ECL signal appeared at onset potential of 0.05 V (vs. Ag/AgCl), and reached the maximum at about −0.15 V (vs. Ag/AgCl), which were quite lower than that in the typical Ru(bpy)32+-oxalate (C2O42−) ECL system. The possible mechanism was discussed in detail. Meanwhile, the low-potential-triggered ECL signals were strong and stable, which were further exploited to detect the carcinoembryonic antigen (CEA). The constructed ECL sensor exhibited a good linearity between the ECL signals and the logarithm of the concentrations of CEA in a range from 0.1 pg mL−1 to 100 ng mL−1 with the detection limit of 0.01 pg mL−1. In addition, the sensor showed a promising potential in clinical detection.