Electrochemiluminescence Mechanisms and Bioanalysis Based on Multishape Gold Nanoparticles and Visualized ATT-Au NCs

Herein, 6-aza-2-thiothymine gold nanoclusters (ATT-Au NCs) were firstly prepared as electrochemiluminescence (ECL) materials by a one-step strategy. The ligand-protected gold nanopolymers successfully enhanced the stability of the solid-state and the ECL performance, thus enhancing ECL signals by simply drying the electrode surface. Meanwhile, gold nanoparticles, gold dimers, gold nanorods (Au NRs) dispersions and gold nanorod dimers were synthesized by chemical reduction, DNA ligation, seed growth and electrostatic adsorption of organic ligands, respectively. Afterwards, we investigated the ECL enhancement mechanisms of a series of gold nanomaterials on ATT-Au NCs possessing ECL stabilization properties. Parallel gold nanorod dimers had the more intense electromagnetic field intensity than gold nanorod monomers, gold nanoparticles, and gold dimers, which considerably enhanced the ECL signal of ATT-Au NCs. Finally, the surface plasmon coupled ECL (SPC-ECL) generated between ATT-Au NCs and Au NR parallel dimer was used for bioanalysis, and a biosensor was designed, which used Cu2O nanoparticles as a quenching probe to generate resonance energy transfer (RET), leading to ECL “signal off”. The combination of signal enhancement and quenching yielded a high signal-to-noise ratio, effectively detecting microRNA-21 (miRNA-21) with improved sensitivity, featuring a linear range of 1 fM to 100 nM and a low detection limit (LOD) of 0.28 fM. Thus, the sensor holds promising applications in biomedical research and clinical diagnosis, presenting a novel detection methodology.