Single-atom iron boosts electrochemiluminescence for ultrasensitive carcinoembryonic antigen detection.

ABSTRACT

A simple and ultrasensitive sandwich-type electrochemiluminescence (ECL) immunosensor has been developed using porous three-dimensional gold nanoparticles (Au NPs) iron(Fe)-zinc(Zn) metal-organic frameworks (Au NPs-FeZn-MOFs@luminol) as high-efficiency ECL signal probes with Fe single-atom catalysts (SACs) (Fe-N-C SACs) as potentially advanced coreaction accelerators and dissolved oxygen as a coreaction agent to realize an H2O2-free amplification method for detecting carcinoembryonic antigen (CEA). The cathodic ECL of luminol, which was usually negligible, increased first. Because the Fe-N-C SACs exhibited an outstanding catalytic performance and a unique electronic structure, different reactive oxygen species (ROS) were generated via the oxygen reduction reaction. ROS oxidized the luminol anions to luminol anion radicals, preventing the time-consuming luminol electrochemical oxidation. Furthermore, the luminol anion radicals generated in situ reacted with ROS to produce potent cathodic ECL emissions. The immunosensor exhibited favorable analytical accuracy (detection range 0.1 pg mL-1 - 80 ng mL-1), and its detection limit for serum samples was 0.031 pg mL-1 (S/N = 3). Consequently, the proposed strategy offers a new approach for early screening of CEA.