Cu-MOFs/GOx Bifunctional Probe-Based Synergistic Signal Amplification Strategy: Toward Highly Sensitive Closed Bipolar Electrochemiluminescence Immunoassay.

A closed bipolar electrochemiluminescence (BP-ECL) platform for sensitive prostate specific antigen (PSA) detection was proposed based on a novel synergistic signal amplification strategy. Specifically, glucose oxidase-loaded Cu-based metal-organic frameworks (Cu-MOFs/GOx) as bifunctional probes were bridged on the anodic interface with the target PSA as the intermediate unit. In virtue of the large loading capacity of Cu-MOFs, a large amount of a co-reactant, i.e., HO in this L-012-based ECL system and gluconic acid were generated on the anodic pole in the presence of glucose. The generated gluconic acid could effectively degrade the Cu-MOFs to release Cu which greatly accelerates the formation of highly active intermediates from co-reactant HO, boosting the ECL intensity. As for the cathodic pole, KFe(CN) with a lower reduction potential is used to reduce the driving voltage and speed up the reaction rate, further strengthening the ECL intensity. Thanks to the synergistic signal amplification effect at both two electrode poles of the BP-ECL system, highly sensitive detection of PSA was realized with a detection limit of 5.0 × 10 g/mL and a wide linear range of 1.0 × 10-1.0 × 10 g/mL. The strategy provides a novel way for signal amplification in the BP-ECL biosensing field.