Ratiometric electrochemiluminescence biosensor for hepatitis C virus E2 protein based on block copolymers-solubilized Ir(ppy)3 with high electrochemiluminescence efficiency

Abstract

Iridium (Ir) complexes have gained remarkable development momentum as candidates for electrochemiluminescence, but their poor solubility in water media greatly limited their application in ECL area. Herein, a facile nanoprecipitation method by encapsulating tris(2-phenylpyridinato)iridium (Ir(ppy)3) into pluronic block copolymers for preparing water-soluble Ir(III) complexes with high ECL emission efficiency was developed. Then, with F-127@Ir(ppy)3 as the anode emitter and g-C3N4 as the cathode emitter, a new ratiometric biosensor based on transition metal complexes was developed for the first time, which was used for ultra-sensitive detection of hepatitis C virus E2 protein. Notably, the ratiometric ECL signal could be mediated by using multifunctional Nb2C nanosheets (Nb2C NSs) with excellent electrocatalytic activity and superoxide dismutase activity, so as to enhance the ECL intensity of anode and quench the response of cathode ECL. Combining Nb2C NSs with the antibody and the specific recognition process, the proposed ECL ratio biosensor showed good performance for E2 with a linear range from 1 × 10−3 ng/mL to 1 × 102 ng/mL and a detection limit of 8.39 × 10−4 ng/mL. The work on designing water-soluble Ir (III) complexes with pluronic block copolymer provides an ingenious approach to broaden the application of poorly soluble complexes in bioassays.