Electrochemiluminescent silica nanoparticles encapsulating structure-optimized iridium complex to sensitively detect acetamiprid residues in tea based on aptamer sensor

To explore novel and efficient ECL luminophores, a series of cationic iridium(III) complexes with 4,7-diphenyl-1,10-phenanthroline as the ancillary ligand and various main ligands were investigated in this work. The comprehensive studies demonstrate complex 1, with 2-phenylbenzothiazole (bt) as main ligand, exhibited superior ECL properties in aqueous buffer compared to other complexes. Importantly, the structurally optimized complex 1 was successfully further encapsulated into silica nanoparticles to prepare electrochemiluminescent iridium(III)-doped silica nanoparticles (Ir@SiO2 NPs). These Ir@SiO2 NPs were then utilized to construct a sensitive and specific ECL aptamer sensor for detecting acetamiprid residues in tea. Notably, our developed sensor demonstrated wide linear ranges from 10 pM to 10 μM and low limit of detection of 1.3 pM. These experimental results presented in this work undoubtedly demonstrate iridium(III)-doped silica nanoparticles as a new and efficient type of ECL nano-emitter have great potentials in ECL-related analytical applications in the future.