Self-Catalyzing Chemiluminescence of Luminol-Diazonium Ion and Its Application for Catalyst-Free Hydrogen Peroxide Detection and Rat Arthritis Imaging.

We report the unique self-catalyzing chemiluminescence (CL) of luminol-diazonium ion (N-luminol) and its analytical potential. Visual CL emission was initially observed when N-luminol was subjected to alkaline aqueous HO without the aid of any catalysts. Further experimental investigations found peroxidase-like activity of N-luminol on the cleavage of HO into OH radical. Together with other experimental evidence, the CL mechanism is suggested as the activation of N-luminol and its dediazotization product 3-hydroxyl luminol by OH radical into corresponding intermediate radicals, and then further oxidation to excited-state 3-N-phthalic acid and 3-hydroxyphthalic acid, which finally produce 415 nm CL. The self-catalyzing CL of N-luminol provides us an opportunity to achieve the attractive catalyst-free CL detection of HO. Experiments demonstrated the 10 M level detection sensitivity to HO as well as to glucose or uric acid if presubjected to glucose oxidase or uricase. With the exampled determination of serum glucose and uric acid, N-luminol shows its analytical potential for other analytes linking the production or consumption of HO. Under physiological condition, N-luminol exhibits highly selective and sensitive CL toward O among the common reactive oxygen species. This capacity supports the significant application of N-luminol for detecting O in live animals. By imaging the arthritis in LEW rats, N-luminol CL is demonstrated as a potential tool for mapping the inflammation-relevant biological events in a live body.