Electrochemiluminescence resonance energy transfer between Ru(bpy)32+@Cu3(HHTP)2 and GO-Au composites for C-reactive protein detection

Designing innovative electrochemiluminescence (ECL) immunosensors is critical for the detection of biomarkers with a low concentration and the precise evaluation of clinical diseases. Herein, a Cu3(hexahydroxytriphenylene)2 (Cu3(HHTP)2) nanoflake-based sandwich-type ECL immunosensor was constructed for C-Reactive Protein (CRP) detection. The Cu3(HHTP)2 nanoflake, an electronically conductive metal–organic framework (MOF), has a periodically arranged porous structure with a cavity size of 2 nm, which not only accommodates a large amount of Ru(bpy)32+ but also confines the spatial diffusion of active species. Therefore, the Ru(bpy)32+-loaded Cu3(HHTP)2 nanocomplex (Ru@CuMOF) as an ECL emitter exhibits an enhanced ECL efficiency. The ECL resonance energy transfer (ECL-RET) was accomplished by combining Ru@CuMOF used as a donor with gold nanoparticles-functionalized graphene oxide nanosheets (GO-Au) utilized as an acceptor. This should be ascribed to the fact that the ECL emission spectrum of Ru@CuMOF shows the strongest signal intensity at 615 nm, overlapping with the absorption spectrum of GO-Au at 580–680 nm. Targeted detection of CRP in human serum samples was achieved by the sandwich-type immunosensor based on the ECL-RET mechanism with a 0.26 pg mL−1 detection limit. The electro-activated hybrids of Cu3(HHTP)2 and ECL emitters provide a new sensing strategy for the high-sensitivity detection of disease markers.