Potential-resolved "in-electrode" type electrochemiluminescence immunoassay based on functionalized g-C3N4 nanosheet and Ru-NH2 for simultaneous determination of dual targets

Here, a novel potential-resolved "in-electrode" type electrochemiluminescence (ECL) immunosensor was fabricated based on two different types of luminant Ru-NH2 and AuNPs/g-C3N4 to realize simultaneous detection of dual targets. In this strategy, anti-CA125(1) and anti-SCCA(1) were immobilized on bare gold electrode as capture probes, which could catch the two corresponding target CA125 and SCCA, and the immobilization of the signal tags was allowed via the interaction between antigen and antibody. In this process, (Ru & anti-CA125(2))@GO and anti-SCCA(2)-AuNPs/g-C3N4 could exhibit two strong and stable ECL emissions at 1.25 V and -1.3 V respectively, which could be used as effective signal tags. Taking advantage of "in-electrode" type ECL immunosensor, all the electrochemiluminophores near the outer Helmholtz plane are "effective" in participating in the electrochemical reactions and emitting ECL signals. Therefore, the dual targets CA125 and SCCA could be detected within the linear ranges of 0.001-100 U/mL and 0.001-100 ng/mL, with detection limits of 0.4 mU/mL and 0.33 pg/mL, respectively. All these results demonstrated that the present potential-resolved "in-electrode" type electrochemiluminescence approach provided a promising analytical method for dual targets analysis with the advantages of simple analytical procedure, small sample volume and lower cost, which made the proposed method potential for clinical detection.