Intramolecular electrochemiluminescence resonance energy transfer by grafting Ru-complexes on donor ligand-rich metal-organic framework nanoplate for ultrasensitive detection of microRNA

Electrochemiluminescence resonance energy transfer (ECL-RET) is an effective method to improve the ECL performance of materials. However, the intermolecular ECL-RET systems still suffered from low ECL-RET efficiency. To improve the ECL-RET efficiency, we established a high-efficient intramolecular ECL-RET system (Ru-Zr12-adb, H2adb = 4,4′-(9,10-anthracenediyl)dibenzoic acid), in which Zr12-adb metal-organic framework (MOF) nanoplate was employed as the donor to enhance the ECL intensity of Ru(bpy)2(mcbpy)2+ (acceptor). Because the high-ordered porous frameworks of Zr12-adb nanoplate not only coordinatively immobilized abundant Ru(bpy)2(mcpbpy)2+ but also realized exact and short-distance intramolecular ECL-RET, thus Ru-Zr12-adb possessed strong ECL emission. Moreover, the easy formation of coordination bonds makes MOFs an ideal platform for conveniently building high-efficient ECL-RET systems, promoting their broad application in ECL sensors. Given the aforementioned merits, Ru-Zr12-adb was chosen as a high-efficient ECL beacon coupled with the catalytic hairpin assembly and double-end DNAzyme-driven DNA walker recycling amplification to build an ultra-sensitive sensor for microRNA-21 assay, which showed wide linearity (10 aM to 100 pM) with a detection limit of 1.9 aM. Collectively, the work showed that using MOFs to immobilize energy donors and energy acceptors concurrently was a simple effective method to build high-efficient ECL-RET materials, which offered new opportunities for fabricating ultrasensitive ECL sensors.