Aggregation-induced electrochemiluminescence of zirconium metal-organic framework with strain-promoted azide-alkyne cycloaddition ligated DNA tetrahedral nanotags for microRNA detection.

In this work, zirconium metal-organic framework (MOF) luminophore named Zr-TCPB with aggregation-induced electrochemiluminescence (AIECL) characteristics was effectively synthesized through the self-assembly of the AIE molecule 1,2,4,5-tetrakis (4-carboxyphenyl) benzene (H4TCPB) as the organic ligand and the metal Zr as the metal node. The framework architecture of Zr-TCPB limited the restriction of intramolecular motions of H4TCPB, enhancing its ECL performance. Furthermore, the high porosity and specific surface area of the MOFs increased more electrochemical active sites. Consequently, we built a novel AIECL biosensor using Zr-TCPB as the emitter for the sensitive detection of microRNA incorporating silver nanoparticles (Ag NPs) labled DNA tetrahedrons signal dual-amplification strategy. Upon the initiation of DNA hairpin opening by microRNA at the electrode interface, the concealed click reaction group was unveiled through strand displacement polymerization, which bioconjugated with a multiple Ag NPs-DNA tetrahedral nanostructures by azide-alkyne cycloaddition click reaction. Additionally, Ag NPs were used as coreaction accelerators to catalyze K2S2O8, generating more SO4•- and thereby amplifying the ECL signals, achieving signal dual-amplification. The established method achieved accurate quantitative detection of miRNA-21 in the range from 100 aM to 10 nM with a low detection limit of 67.2 aM. More importantly, it exhibited exceptional selectivity and stability, making it a promising approach to monitor miRNA biomarkers, while opening up fresh avenues to bolster the application potential of AIECL MOFs and azide-alkyne cycloaddition click reaction in biosensors.