Simultaneous detection of two tumor markers using electrochemical immunosensor based on ultrathin metal-organic framework derived nanosheets as redox probes

This study involves the fabrication of a sandwich-type electrochemical immunosensor for sensitive and simultaneous detection of alpha-fetoprotein (AFP) and cancer embryo antigen (CEA). Gold nanoparticle (Au NP)-modified ultrathin metal-organic framework nanosheets (UMOFNs) were prepared (denoted as Cu-UMOFNs@Au NPs and Co-UMOFNs@Au NPs). Furthermore, the Cu-UMOFNs@Au NPs and Co-UMOFNs@Au NPs were used as redox probes to label different antibodies. Subsequently, any potential active sites that remained were blocked using glucose oxidase. Dual catalysis amplification was achieved using the prepared MOF-derived materials via in situ catalysis of glucose to produce H2O2 in the presence of glucose oxidase. H2O2 was further catalyzed by Cu-UMOFNs@Au NP- and Co-UMOFNs@Au NP-derived materials to obtain better signal responses. The results revealed that the linear range of the proposed immunosensor for the simultaneous detection of AFP was 0.001-100 ng mL(-1) (detection limit, 0.28 pg mL(-1); S/N = 3) and that for the simultaneous detection of CEA was 0.001-80 ng mL(-1) (detection limit, 0.31 pg mL(-1); S/N = 3). Notably, the proposed method promises rapid, simple, and cost-effective analysis of biological samples.