Ultrasensitive Electrochemiluminescence Biosensor with ZIF-67@MXene as an Efficient Co-Reaction Accelerator and Plasmonic Nanozyme as a Smart Signal Amplification Probe.

Exploring novel electrochemiluminescence (ECL) co-reaction accelerators to construct ultrasensitive sensing systems is a prominent focus for developing advanced ECL sensors. However, challenges still remain in finding highly efficient accelerators and understanding their promoting mechanisms. In this paper, ZIF-67@MXene nanosheet composites, with highly conductive in-plane structure and confined-stable pore/channel, are designed to act as high-efficient co-reaction accelerators and achieve a significant enhancement in the luminol-HO based ECL system. Mechanism investigation suggests that hydroxyl radicals (·OH) and singlet oxygen (O) can be selectively and preferentially generated on ZIF-67@MXene due to the stable and efficient absorption of ·OH and O, leading to a remarkable enhancement in the ECL efficiency of luminol (830%). Finally, by designing a plasmonic NH-MIL-88@Pd nanozyme, an "on-off" switch immunosensor is constructed for the detection of prostate-specific antigen (PSA). Based on the multiple signal amplification effect, the linear detection range for PSA is expanded by three orders of magnitude. The detection limit is also improved from 1.44 × 10 to 9.1 × 10 g mL. This work proposes an effective method for the preparation of highly efficient co-reaction accelerators and provides a new strategy for the sensitive detection of cancer markers.