A signal-off electrochemiluminescence immunosensor based on AgS quantum dot quenching luminol modified Ag/Cu2O/Ti3C2 nanocomposites for h-FABP detection†

In this study, we successfully developed a highly sensitive electrochemiluminescence (ECL) sensor based on the ECL resonance energy transfer mechanism for detecting the key biomarker of acute myocardial infarction, heart-type fatty acid binding protein (h-FABP). Through the meticulous design of the Ag/Cu₂O/Ti₃C₂ ternary nanocomposite material, this material demonstrated significant catalase-like catalytic activity, enabling the efficient decomposition of H₂O₂ to generate more superoxide radicals (O₂˙⁻), thereby significantly enhancing the ECL signal of the luminol–H₂O₂ system. Notably, AgS quantum dots (AgS QDs), due to broad-spectrum ultraviolet absorption overlapping with the ECL emission spectrum of luminol, triggered an efficient energy resonance transfer effect, resulting in a decrease of ECL intensity. NH₂-MIL-101(Fe) was coupled with AgS QDs (AgS QDs@NH₂-MIL-101(Fe)), which can further enhance the quenching efficiency. Based on this signal-off strategy, an ultrasensitive detection platform for h-FABP was successfully constructed. Experimental results indicated that the immunosensor exhibited an excellent response relationship over a wide linear range from 1.00 fg mL⁻¹ to 100 ng mL⁻¹, and a low detection limit of 0.36 fg mL⁻¹ (S/N = 3) was reached. This study provides an innovative methodological approach for ultra-trace detection of myocardial injury markers and demonstrates significant application potential in early clinical diagnosis.