A synchronous dual-mode electrochemiluminescence/electrochemical detection of carcinoembryonic antigen at low potential

Recently, dual-mode electrochemiluminescence/electrochemical (ECL/EC) detection strategies have been used for improving the detection accuracy by mutual correction. Unfortunately, the ECL and EC signals usually appeared at two far-apart potentials, resulting in different test environments and unnecessary side effects. To solve this problem, in this work, we constructed a dual-mode ECL/EC aptsensor, achieving the synchronous ECL and EC detections for the carcinoembryonic antigen (CEA) at the same low potential. The CEA aptamer (Apt) was firstly anchored on reduced graphene oxide (rGO), which promoted the subsequent adsorption of cationic Hemin through the electrostatic and π-π stacking interaction. The absorbed Hemin could accelerate the electro-reduction of dissolved oxygen in the air-saturated Ru(bpy)₃²⁺-Na₂C₂O₄ system, generating not only a reduction peak current at −0.2 V (vs. Ag/AgCl) but also many hydroxyl radicals (HO‧). The HO‧ could oxidize the Ru(bpy)₃²⁺ to be Ru(bpy)₃³⁺, followed by the ECL signal produced by the reaction between Ru(bpy)₃³ and Na₂C₂O₄. So, ECL and EC peak signals synchronously emerged at −0.2 V (vs. Ag/AgCl). When the CEA was present, it took the Apt away from electrode and decreased the amount of Hemin followed by the reduced reduction current and ECL, managing synchronous dual-mode detection in the same test environment. The obtained dual-mode sensing platform exhibited a good analytical performance in the clinical application.