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

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-C 3 N 4 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 Nb 2 C nanosheets (Nb 2 C 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 Nb 2 C 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 × 10 2  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.