Combination of Ternary Electrochemiluminescence System of BNQDs/AgMOG-K 2 S 2 O 8 and Electrochemiluminescence Resonance Energy Transfer Strategy for Ultrasensitive Immunoassay of Amyloid-β Protein.

In this work, based on boron nitride quantum dots (BNQDs) as energy donors and MnO 2 @MWCNTs-COOH as energy receptors, we designed an efficient electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor for the detection of amyloid-β (Aβ 42 ) protein, a biomarker of Alzheimer's disease (AD). First, the signal amplification of a ternary ECL system composed of BNQDs (as the ECL emitter), K 2 S 2 O 8 (as the coreactant), and silver metal-organic gels (AgMOG, as the coreaction accelerator) was realized, and PDDA as stabilizer was added, a strong and stable initial ECL signal was obtained. AgMOG could not only support a large amount of BNQDs and Aβ 42 capture antibody (Ab 1 ) through Ag-N bond but also exhibit excellent ECL catalytic performance and enhance the luminescent intensity of BNQDs@PDDA-K 2 S 2 O 8 system. In addition, due to the broad absorption spectrum of MnO 2 @MWCNTs-COOH and the extensive overlap with the ECL emission spectrum of BNQDs, the quenching probe Ab 2 -MnO 2 @MWCNTs-COOH could be introduced into the ternary system through a sandwich immune response. On this basis, the signal on-off ECL immunosensor was constructed to achieve the ultrasensitive detection of Aβ 42 through signal transformation. Under the optimal conditions, the prepared ECL biosensor manifested a wide linear range (10 fg/mL-100 ng/mL) with a detection limit of 2.89 fg/mL and showed excellent stability, selectivity, and repeatability, which provided an effective strategy for the ultrasensitive detection of biomarkers in clinical analysis.