A novel potential-resolved electrochemiluminescence immunosensor for the simultaneous determination of brain natriuretic peptide and cardiac troponin I

In the electrochemiluminescence (ECL) assays, it is difficult to find potential-resolved ECL luminators excluding the mutual interference of their coreactants and the resonance energy transfer between them, which makes it a great challenge to achieve a potential resolution-based multiple immunoassay. A novel potential-resolved ECL strategy based on N-(aminobutyl)-N-(ethylisoluminol) (ABEI) and graphiticphase carbon nitride nanosheet (g-C3N4) was constructed for synchronously multiplexed immunoassay of brain natriuretic peptide (BNP) and cardiac troponin I (cTnI). Au nanoparticles were modified onto the electrode surface to capture the anti-cTnI(1) and anti-BNP1. The antigens of cTnI and BNP, secondary antibody composites anti-cTnI(2)-AuNPs@ABEI and anti-BNP2-AuNPs@g-C3N4 were stepwise incubated onto the electrode surface. With the increase in the concentration of BNP and cTnI, the ECL signals at +0.7 V from ABEI and -1.5 V from g-C3N4 were simultaneously increased, thus achieving the synchronous immunoassay of BNP and cTnI. The detection limits of cTnI and BNP were 3.2 pg/mL and 3.8 pg/mL, respectively. The integration of ABEI/O-2 and g-C3N4/S2O82- system avoided the defects of the currently multiplexed immunoassay, thus providing an attractive ECL platform for synchronous determination of multiple biomarkers at the same sensitive interface.