Alkynyl Ligands Templated Assemblies of Silver Nanoclusters with Exceptional Electrochemiluminescence Activity for Pancreatic Cancer Specific tsRNAs Measurement

Proper manipulation of the ligand complex on the motifs of metal nanoclusters (MNCs) to form an ordered self-assembly is an effective approach to enhance the electrochemiluminescence (ECL) emission of MNCs. We report a facile approach for the preparation of self-assembled AgNCs (AgNCs_Assy) induced by alkynyl ligands with enhanced ECL and stability. The formation of these AgNCs_Assy was simultaneously driven by the diverse coordination modes of alkynyl ligands with Ag and intercluster interactions, for which it was found that the para-substituted alkynyl ligands exhibited apparently irregular nanoparticles, while the monosubstituted counterparts were present in the form of ribbons. The calculations revealed that the energy gap between the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) played a crucial role in their ECL emissions because of the substituent effects, especially, the low-lying LUMO levels could help to enhance the ECL emission. Moreover, mechanistic studies revealed that both the coreactant and alkynyl ligands made significant contributions to the ECL performance. Concurrently, the CRISPR-associated proteins (CRISPR-Cas) 12a system shows great potential in biosensing applications due to the advantages of easy design and precise targeting. As a proof of concept, we integrated the cascade amplification of catalytic hairpin assembly (CHA) circuit and the collateral cleavage activity of CRISPR-Cas12a to construct an ultrasensitive ECL biosensor for pancreatic cancer (PC)-specific tsRNAs, with a detection limit of 3.33 fM. This work is not only instructive for the synthesis of self-assembled MNCs with high ECL activities but also contributes to the understanding of the ECL mechanism of self-assembled MNCs.