In this paper, a novel donor–acceptor pair was creatively proposed based on the principle of electrochemiluminescence resonance energy transfer (ECL-RET): luminol immobilized on polyethyleneimine (PEI)-functionalized manganese-based single-atom nanozymes (Mn SANE/PEI-luminol, donor) and a PtCu-grafted hollow metal polydopamine framework (PtCu/h-MPF, acceptor). A quenched ECL immunosensor was constructed for the ultrasensitive analysis of carcinoembryonic antigen (CEA). Mn SANE, as an efficient novel coreaction accelerator with the outstanding performance of significantly activating H2O2 to produce large amounts of ROS, was further modified by the coreactant PEI, which efficiently immobilized luminol to form a self-enhanced emitter. As a result, the electron transport distance was effectively shortened, the energy loss was reduced, and luminol achieved a high ECL efficiency. More importantly, PtCu-grafted h-MPF (PtCu/h-MPF) was proposed as a novel quencher. The UV–vis spectra of PtCu/h-MPF partially overlap with the ECL spectra of Mn SANE/PEI-luminol, which can effectively trigger the ECL-RET behavior between the donor and the acceptor. The multiple quenching effect on Mn SANE/PEI-luminol was achieved, which significantly improved the sensitivity of the immunosensor. The prepared immunosensor exhibited good linearity in the concentration range of 10–5 to 80 ng/mL. The results indicate that this work provides a new method for the early detection of CEA in clinical diagnosis.

To sensitively monitor trace amounts of alternariol (AOH) in fruits, a dual-mode aptamer sensor utilizing the dual-function nanomaterial PoPD/Ru–Au was developed. This sensor provides both electrochemical (EC) and electrochemiluminescence (ECL) signals, which can greatly avoid the potential false positive of the traditional single signal, thus enhancing the accuracy and reliability of detection results. Polyo-phenylenediamine (PoPD), known for its favorable EC response, can also assist in enhancing the ECL behavior of Ru–Au. Furthermore, Ru–Au demonstrates excellent ECL performance and effectively activates K2S2O8 to amplify the EC response of PoPD. The complementary effect of the two can effectively amplify the final detection signal. Additionally, the PoPD/Ru–Au nanomaterial exhibits excellent electrical conductivity, further enhancing the EC and ECL response signals. The experimental results demonstrate that the EC detection range of AOH was 0.01–100 ng/mL, while the ECL detection range was 0.001–100 ng/mL, both exhibiting a satisfactory linear relationship. Therefore, the mutual verification of the detection results can be highly realized, and the purpose of avoiding wrong detection can be achieved.

In this work, we propose a novel double-quenching electrochemical luminescence (ECL) strategy; this strategy is based on the double-quenching effect of Ru­(bpy)3 2+-functionalized three-dimensional (3D) metal–organic framework (MOF) by MnO2/PDA. An ECL immunosensor for ultrasensitive detection of alpha-fetoprotein (AFP) has been designed. TMU-3 with a rich mesoporous structure can be used to encapsulate Ru­(bpy)3 2+, which can effectively reduce the leakage of Ru­(bpy)3 2+. Moreover, the ultraviolet–visible (UV–vis) absorption spectrum of the lamellar MnO2/PDA nanomaterials with a nanometer scale of about 1 μm overlaps with the ECL emission spectrum of the porous bamboo leaf-like Ru­(bpy)3 2+@TMU-3 with a nanometer scale of about 1 μm. Thus, an ECL resonance energy transfer (ECL-RET) mechanism between Ru­(bpy)3 2+@TMU-3 (donor) and MnO2/PDA (recipient) is formed. In this way, an ECL immunosensor with a dual-quenching strategy for ECL signal is developed. In order to test the practicability of this method in clinical analysis, the detection target marker AFP content ranged from 0.01 pg/mL to 5 ng/mL and the detection limit was set to 10.7 fg/mL. In summary, this work demonstrates the detection and application of a signal-quenched ECL immunosensor and ECL immunoassay based on a luminescence-functionalized MOF system for biomarker detection. It indicates a great prospect in the analysis of other biomarkers and clinical analysis.

Early detection of tumour markers is essential for the timely treatment of cancer to realise the sensitive detection of Carcinoembryonic antigen (CEA). We chose electrochemical immunosensor as a simple analytical...