Gold Nanoparticle Triggered Chemiluminescence between Luminol and AgNO3

It was found that luminol could react with AgNO 3 in the presence of gold colloid to generate chemiluminescence (CL) at 425 nm. UV−visible spectra and X-ray photoelectron spectra showed that AgNO 3 was reduced by luminol to Ag in the CL reaction, which covered on the surface of gold nanoparticles to form Au/Ag core/shell nanoparticles. The luminophor was identified by the CL spectrum as 3-aminophthalate. The effects of Au/Ag core/shell nanoparticles with various compositions on the luminol−AgNO 3 system and the CL kinetics were also studied. On this basis, a CL reaction mechanism involving catalysis is proposed. When Au colloid was injected into the mixture of luminol and AgNO 3, AgNO 3 reacted rapidly with luminol under the catalysis of gold nanoparticles to produce Ag and luminol radicals, which reacted with the dissolved oxygen, accompanying a light emission; then, with instant deposition of Ag atoms on the surface of Au particles, the catalytic activity declined, leading to a sharp decrease in CL intensity and a slow growth of core/shell nanoparticles. The new CL system has the advantages of low background and good stability, and gold nanoparticles have excellent biocompatible property. It may find future applications in immunoassay and DNA detection.