Alkynyl Ligands\nTemplated Assemblies of Silver Nanoclusters\nwith Exceptional Electrochemiluminescence Activity for Pancreatic\nCancer Specific tsRNAs Measurement

Proper manipulation of the ligand complex on the motifs\nof metal\nnanoclusters (MNCs) to form an ordered self-assembly is an effective\napproach to enhance the electrochemiluminescence (ECL) emission of\nMNCs. We report a facile approach for the preparation of self-assembled\nAgNCs (AgNCs<sub>Assy</sub>) induced by alkynyl ligands with enhanced\nECL and stability. The formation of these AgNCs<sub>Assy</sub> was\nsimultaneously driven by the diverse coordination modes of alkynyl\nligands with Ag and intercluster interactions, for which it was found\nthat the para-substituted alkynyl ligands exhibited apparently irregular\nnanoparticles, while the monosubstituted counterparts were present\nin the form of ribbons. The calculations revealed that the energy\ngap between the highest occupied molecular orbitals (HOMOs) and the\nlowest unoccupied molecular orbitals (LUMOs) played a crucial role\nin their ECL emissions because of the substituent effects, especially,\nthe low-lying LUMO levels could help to enhance the ECL emission.\nMoreover, mechanistic studies revealed that both the coreactant and\nalkynyl ligands made significant contributions to the ECL performance.\nConcurrently, the CRISPR-associated proteins (CRISPR-Cas) 12a system\nshows great potential in biosensing applications due to the advantages\nof easy design and precise targeting. As a proof of concept, we integrated\nthe cascade amplification of catalytic hairpin assembly (CHA) circuit\nand the collateral cleavage activity of CRISPR-Cas12a to construct\nan ultrasensitive ECL biosensor for pancreatic cancer (PC)-specific\ntsRNAs, with a detection limit of 3.33 fM. This work is not only instructive\nfor the synthesis of self-assembled MNCs with high ECL activities\nbut also contributes to the understanding of the ECL mechanism of\nself-assembled MNCs.