Pii: S0304-3835(02)00547-5

As a chemiluminescence (CL) probe, 3,7-dihydro-6-{4-{2-(N 0-(5-fluoresceinyl) thioureido)ethoxy}phenyl}-2-methylimidazo{1,2-a}pyrazin-3-one dosium salt (FCLA) can sensitively and specifically react with singlet oxygen (O2) and superoxide (O2 ). Based on the fact that photosensitization action involves O2 generation, this report presents a novel method for localization of tumor mediated by FCLA. In experiments, FCLA was used as an optical reporter of O2 produced from photosensitization reaction of hematoporphyrin derivative. The effects of azide inhibition and deuterium enhancement on photosensitized CL indicated that O2 molecules generated during photosensitization action could be measured and imaged. In vivo experiments in vivo with tumor-bearing nude mice showed a clear CL image of tumor. The study suggests that CL imaging method may be applicable to the detection of O2 and the diagnosis of superficial tumors. q 2002 Elsevier Science Ireland Ltd. All rights reserved.