Coupling O2 and K2S2O8 Dual Co‐reactant with Fe‐N‐C Modified Electrode for Ultrasensitive Electrochemiluminescence Signal Amplification.

The sensitivity of electrochemiluminescence (ECL) sensor relies on the co‐reactant and the electrode modification materials. Herein, dual co‐reactants (O2 and K2S2O8) and porous carbon with doped N and Fe3O4 (Fe‐N−C) materials modified electrode were proposed for ECL signal amplification in a quantum dots (QDs) ECL system. Firstly, Fe‐N−C materials were synthesized and the effect of pyrolysis temperature on Fe‐N−C materials was evaluated towards ECL intensity. The developed ECL sensor exhibited high sensitivity and specificity towards oxytetracycline (OTC) detection with a detection limit of 0.27 pM (≈ 0.12 ng L−1). Doped N in porous Fe‐N−C materials not only promoted the O2 reduction reaction (ORR) but also accelerated the conversion of Fe2+/Fe3+ in Fe3O4, which catalyzed co‐reactants to their relevant free radicals (SO4⋅− and ⋅OH). Moreover, the decomposition efficiency of K2S2O8 and generation of free radical were promoted through the reaction between OH⋅ and K2S2O8, as well as SO4⋅− and H2O. Therefore, the amounts of excited QDs were increased via the energy and electron transfer process between QDs and free radicals, resulting in a highly enhanced ECL signal. The proposed signal amplification strategy offered an efficient way to improve the catalytic activity of ECL reagents and to boost the sensitivity of ECL sensors. Dual co‐reactants (O2 and K2S2O8) and Fe‐N−C materials modified electrode were designed to boost the signal amplification in a quantum dots ECL system. Based on the specific recognition of sandwich‐type structure with antibody and aptamer, ECL sensors were applied for OTC detection by monitoring ECL signal. The ECL sensor exhibited high sensitivity and specificity with detection limit of 0.27 pM (≈ 0.12 ng L−1). [ABSTRACT FROM AUTHOR]