Luminol–silver nitrate chemiluminescence enhancement induced by cobalt ferrite nanoparticles
✍ Scribed by Wenbing Shi; Hui Wang; Yuming Huang
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 407 KB
- Volume
- 26
- Category
- Article
- ISSN
- 1522-7235
- DOI
- 10.1002/bio.1268
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✦ Synopsis
CoFe 2 O 4 nanoparticles (NPs) could stimulate the weak chemiluminescence (CL) system of luminol and AgNO 3 , resulting in a strong CL emission. The UV-visible spectra, X-ray photoelectron spectra and TEM images of the investigated system revealed that AgNO 3 was reduced by luminol to Ag in the presence of CoFe 2 O 4 NPs and the formed Ag covered the surface of CoFe 2 O 4 NPs, resulting in CoFe 2 O 4 -Ag core-shell nanoparticles. Investigation of the CL reaction kinetics demonstrated that the reaction among luminol, AgNO 3 and CoFe 2 O 4 NPs was fast at the beginning and slowed down later. The CL spectra of the luminol-AgNO 3 -CoFe 2 O 4 NPs system indicated that the luminophor was still an electronically excited 3-aminophthalate anion. A CL mechanism has been postulated. When the CoFe 2 O 4 NPs were injected into the mixture of luminol and AgNO 3 , they catalyzed the reduction of AgNO 3 by luminol to produce luminol radicals and Ag, which immediately covered the CoFe 2 O 4 NPs to form CoFe 2 O 4 -Ag core-shell nanoparticles, and the luminol radicals reacted with the dissolved oxygen, leading to a strong CL emission. With the continuous deposition of Ag on the surface of CoFe 2 O 4 NPs, the catalytic activity of the core-shell nanoparticles was inhibited and a decrease in CL intensity was observed and also a slow growth of shell on the nanoparticles.