Double electrochemiluminescence quenching effects of Fe3O4@PDA-CuXO towards self-enhanced Ru(bpy)32+ functionalized MOFs with hollow structure and it application to procalcitonin immunosensing

Abstract The rapid and reliable measurement of procalcitonin (PCT) level exerts a prominent impact on controlling infections and preventing septicemia. This work presents a “signal on-off” electrochemiluminescence (ECL) immunosensor for ultrasensitive PCT detection based on the double quenching effects of Fe3O4@PDA-CuxO towards a self-enhanced Ru (bpy)32+-functionalized metal organic framework (MOF). Specifically, mesoporous and hollow MIL-101(Al)–NH2 is first applied in ECL system to load Ru (bpy)32+ abundantly and stably. Poly (ethylenimine), as the coreactant, is covalently linked with MIL-101(Al)–NH2 to prevent the leakage of Ru (bpy)32+ and form a self-enhanced Ru complex, thus strong and stable ECL signals are obtained initially. To achieve high-efficiency quenching of “signal on” state, Fe3O4@PDA-CuxO-Ab2 is synthesized tactfully as the quenching probe by which catechol or benzoquinone units in PDA and Cu2+ adsorbed by PDA quench the excited states of Ru (bpy)32+ via electron transfer and resonance energy transfer. In this way, a rapid and robust signal-quenched type ECL immunosensor is developed for PCT measurement with a detection limit of 0.18 pg mL−1 and a dynamic range from 0.0005 ng mL−1 to 100 ng mL−1. Given desirable selectivity, stability and reproducibility, the elaborated ECL immunoassay based on luminescence-functionalized MOF prefigures its great promise in bioanalysis of PCT and other biomarkers.