Cathodic electrochemiluminescence of Ru(bpy)32+ based on porous partially reduced graphene oxide for detecting carcinoembryonic antigen

Up to now, tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) has been widely used in electrochemiluminescence (ECL) detection. However, very positive (>1.0 V vs Ag/AgCl) or negative potential (near −2.0 V vs Ag/AgCl) has to be applied to trigger its ECL. In this work, Ru(bpy)32+ could obtain an intensive and stable cathodic ECL at an excitation voltage of −0.2 V (vs Ag/AgCl) on porous partially reduced graphene oxide (PPRGO), attributing to its excellent electrochemical performance toward oxygen reduction reaction. The mild potential could prevent the electronic damage to the biomolecules. Based on quenching effect of MoS2 nanoflowers, the cathodic ECL was used to construct a sandwich “signal-off” ECL immunosensor, which achieved a sensitive detection of carcinoembryonic antigen (CEA) under optimized conditions. A linear calibration curve from 10 fg mL−1 to 10 ng mL−1 was obtained with the low detection limit of 2.6 fg mL−1 (S/N = 3). In addition, the sensor demonstrated good specificity, stability and reproducibility, and the detection of actual samples obtained satisfactory results. The proposed strategy has a potential application prospect in clinical detection.