Electrochemiluminescence immunosensor based on the quenching effect of CuO@GO on m-CNNS for cTnI detection

A sandwich-type electrochemiluminescence (ECL) immunosensor based on the resonance energy transfer (RET) was proposed for ultrasensitive detection of cardiac troponin I (cTnI). The RET behavior could be generated between graphite carbon nitride nanosheets (m-CNNS) as donor and copper oxide@graphene oxide (CuO@GO) as acceptor, achieving the quenching effect of CuO@GO on m-CNNS for cTnI detection. The m-CNNS synthesized by mechanical grinding of the graphite carbon nitride (CN) not only has better dispersion and higher specific surface area, but also has high luminous efficiency and stable chemical properties. Therefore, m-CNNS was used as the matrix material and luminophore. As the acceptor, CuO@GO prepared by in-situ chemical synthesis of CuO NPs onto GO sheets also has a high specific surface area, which could be used as a label of secondary antibody (Ab₂). Under optimal conditions, cTnI could be determined within the linear range of 0.1 pg mL^-1 to 100 ng mL^-1 and had a low detection limit (0.028 pg mL^-1, S/N = 3). Meanwhile, the prepared ECL immunosensor possessed great stability, specificity and reproducibility, providing a new method for detecting cTnI and other biomarkers.