Metal-organic layers-catalyzed amplification of electrochemiluminescence signal and its application for immunosensor construction

Electrochemiluminescence (ECL) has been widely utilized in immunoassay. The amplification of ECL signal can be effectively realized through the modification of functional nanomaterials, thereby obtaining accurate detection results. In this work, a hybrid material AuNPs@Fe-Zr-MOL was prepared based on Au nanoparticles (AuNPs) and metal-organic layers (MOLs), a novel kind of ultra-thin metal-organic frameworks, for the amplification of the ECL signal of luminol. In this hybrid material, Fe-Zr-MOL was synthesized by introducing the catalytic active site of Fe2+ into Zr-MOL through the coordination interaction. Fe-Zr-MOL could enhance the ECL signal of luminol effectively owing to its peroxidase-like activity. In particular, in comparison with three-dimensional MOFs, Fe-Zr-MOL could expose more active sites for luminol catalysis benefiting from its planar structure, thus enhancing the conductivity availably. While, another key member AuNPs could not only improve the efficiency of electron transport, but also be used for antibody conjugation. Further, a sandwich immunosensor was constructed based on antibody-conjugated AuNPs@Fe-Zr-MOL for the detection of alpha fetoprotein (AFP). The results showed that the as-prepared immunosensor could enhance the amplification of ECL signal effectively and realize effective immunodetection of AFP. This work extends the application of MOLs in nanozyme catalyzed amplification of ECL signal and the construction of immunosensor.