Electrochemiluminescence Immunosensor for the Detection of Carcinoembryonic Antigen Based on Oxygen Vacancy-Rich Co₃O₄ Nanorods and Luminol

The oxygen vacancy of non-noble-metal nanocatalysts used for an oxygen evolution reaction (OER) has hardly been exploited for electrochemiluminescence (ECL) immunosensing. Here, oxygen vacancy-rich Co3O4 nanorods (NRs) were prepared by treating Co3O4 NRs with a NaBH4 solution. The oxygen vacancy-rich Co3O4 NRs could promote the OER and generation of radicals, thus increasing the ECL intensity of the superoxide radical (O2•–)–luminol system in a neutral medium without other co-reactants (e.g., H2O2 and dissolved O2). Hence, the nanocomposite of oxygen vacancy-rich Co3O4 NRs and luminol was promising for ECL analysis. As proof of concept, a novel O2•––luminol ECL sensor was developed for the detection of carcinoembryonic antigen (CEA). It exhibited high selectivity and sensitivity; the linear detection range was 0.005–500 ng/mL and the detection limit was 0.0029 ng/mL. The ECL sensor was applied for the detection of CEA in real samples to evaluate its application feasibility, and satisfactory results were obtained.