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 (HO) with a mild potential range from -0.1 to 0.6 V. Luminol could produce a strong cathodic ECL (E) induced by hydroxyl radicals (HO‧) from the reduction of HO, and a relatively weak anodic ECL (E). After the ferrocene modified CEA aptamer (Apt-Fc) was attached, Fc could promote E by catalyzing the oxidation of HO, and reduce E by consuming HO‧. With the cycling amplification of the exonuclease I, CEA could substantially reduce the amount of Apt-Fc, resulting in the decrease of E and the rise of E. So, the ratio of E to E (E/E) was used as the detection signal, realizing the sensitive determination of CEA from 0.1 pg mL to 10 ng mL with a LOD of 41.85 fg mL (S/N = 3). The developed sensor demonstrated excellent specificity, stability and reproducibility, with satisfactory results in practical detection.