Electrochemiluminescence quenching effect of CuO towards flower-like ferric ion-doped g-CN and its application for Cyfra21-1 immunosensing.

In this article, ferric ion-doped floral graphite carbon nitride (Fe-CN-3, energy donor) was used to construct the substrate of the immunosensor and copper oxide nanocubes (CuO, energy acceptor) were taken as an efficient ECL quenching probe. A sandwich quench electrochemiluminescence (ECL) immunosensor for soluble cytokeratin 19 fragment (Cyfra21-1) detection was preliminarily developed based on a novel resonant energy transfer donor-acceptor pair. Fe-CN-3, a carbon nitride that combines the advantages of metal ion doping as well as morphology modulation, is used in ECL luminophores to provide more excellent ECL performance, which makes a significant contribution to the application and development of carbon nitride in the field of ECL biosensors. The regular shape, high specific surface area and excellent biocompatibility of the quencher CuO nanocubes facilitate the labeling of secondary antibodies and the construction of sensors. Meanwhile, as an energy acceptor, the UV absorption spectrum of CuO can overlap efficiently with the energy donor's ECL emission spectrum, making it prone to the occurrence of ECL-RET and thus obtaining an excellent quenching effect. These merits of the donor-acceptor pair enable the sensor to have a wide detection range of 0.00005-100 ng/mL and a low detection limit of 17.4 fg/mL (S/N = 3), which provides a new approach and theoretical basis for the clinical detection of lung cancer.