Electrochemiluminescence quenching effect of Cu2O towards flower-like ferric ion-doped g-C3N4 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 (Cu 2 O, 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 Cu 2 O nanocubes facilitate the labeling of secondary antibodies and the construction of sensors. Meanwhile, as an energy acceptor, the UV absorption spectrum of Cu 2 O 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. [Display omitted] • A quenched ECL immunosensor prepared based on novel nanocomposites. • Fe3+ was introduced into the "nitrogen tank" of g-C 3 N 4 to improve the ECL performance. • Cu 2 O nanocubes were firstly used as efficient quenching prober of ECL signal. • The designed immunosensor exhibited low detection limit of 17.4 fg/mL for Cyfra21-1. [ABSTRACT FROM AUTHOR]