Dual-potential ratiometric electrochemiluminescence based on single emitter and single coreactant for the sensitive detection of carcinoembryonic antigen

Dual-potential ratiometric electrochemiluminescence (ECL) is in favor of resistance to environmental interference. However, two kinds of emitters or coreactants, and a wide scan potential range (>2 V) are mandatory. This work developed a new dual-potential ratiometric ECL sensor for detection of carcinoembryonic antigen (CEA) using single emitter (luminol) and single coreactant (H2O2) with a mild potential range from -0.1 to 0.6 V. Luminol could produce a strong cathodic ECL (E-c) induced by hydroxyl radicals (HO center dot) from the reduction of H2O2, and a relatively weak anodic ECL (E-a). After the ferrocene modified CEA aptamer (Apt-Fc) was attached, Fc could promote E-a by catalyzing the oxidation of H2O2, and reduce E-c by consuming HO center dot. With the cycling amplification of the exonuclease I, CEA could substantially reduce the amount of Apt-Fc, resulting in the decrease of E-a and the rise of E-c. So, the ratio of E-c to E-a (E-c/E-a) was used as the detection signal, realizing the sensitive determination of CEA from 0.1 pg mL(-1) to 10 ng mL(-1) with a LOD of 41.85 fg mL(-1) (S/N = 3). The developed sensor demonstrated excellent specificity, stability and reproducibility, with satisfactory results in practical detection.