A sensitive electrochemiluminescence immunosensor for CEA detection based on the ECL-RET between zinc-based metal–organic frameworks and ZiF-8@PDA

In this study, we developed a new system that using zinc-based metal–organic frameworks NH₂-Zn-PTC as the donor and ZiF-8@PDA as the acceptor to achieve highly sensitive detection of carcinoembryonic antigen (CEA), using the fundamentals of electrochemiluminescence resonance energy transfer (ECL-RET). Firstly, the aggregation-induced quenching effect (ACQ) was eliminated by the coordination of PTC in MOF and the ECL signal was improved. Secondly, the ECL signal was further amplified by using Au NPs and amino groups as co-reaction promoters to generate more SO₄^.−. In addition, the introduction of ZiF-8@PDA as an acceptor and NH₂-Zn-PTC as a donor took advantage of the feature of partial overlap of the UV–vis absorption spectrum and ECL emission spectra between the two, thereby effectively initiating the ECL-RET behavior, which improved the detection sensitivity of the sensor. The prepared immunosensor showed good linearity in the concentration range of 10⁻⁴ to 80 ng/mL with a detection limit of 18.20 fg/mL. This makes it promising for clinical testing of tumor markers.