title: Direct measurement of singlet oxygen by using a photomultiplier tube-based detection system.
abstract: The effective dosimetry for photodynamic therapy (PDT) can be specified by direct measurement of singlet oxygen ((1)O2) production. The purpose of this study was to investigate the feasibility of a newly developed photomultiplier tube (PMT)-based singlet oxygen detection (SOD) system. The lowest and highest (1)O2 concentrations detectable by the PMT-SOD system were 15nM and 10μM, respectively. Dose-dependent quenching, by NaN3, of the fluorogenic reaction was observed, which was negatively correlated with the (1)O2 level measured by the PMT-SOD system. The lifetime of (1)O2, as measured by the PMT-SOD system, was found to be lengthened when H2O was replaced with deuterium oxide. (1)O2 photon counts were significantly and dose-dependently correlated with intracellular fluorescence intensity after photosensitizer treatments. In vitro cell viability test and in vivo xenografted-tumor mass shrinkage showed a positive association between PDT-induced cytotoxicity and (1)O2 production concomitantly measured by the PMT-SOD system. It was concluded that the PMT-SOD system is capable of measuring (1)O2 production directly and accurately, demonstrating that this system can be useful in the determination of dosimetry for PDT.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea.
authors.forename: In-Wook
authors.initials: IW
authors.lastname: Kim
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea. Electronic address: parkjerry@catholic.ac.kr.
authors.forename: Jae Myung
authors.initials: JM
authors.lastname: Park
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea.
authors.forename: Yoon Jin
authors.initials: YJ
authors.lastname: Roh
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea.
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 137-701, Republic of Korea.
authors.forename: Myung-Gyu
authors.initials: MG
authors.lastname: Choi
authors.affiliation: Wellman Center for Photomedicine, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Tayyaba
authors.initials: T
authors.lastname: Hasan
mesh_terms: D045744:Cell Line, Tumor; D006801:Humans; D057230:Limit of Detection; D026082:Singlet Oxygen / Q000032:analysis*; D013050:Spectrometry, Fluorescence
chemical_list: D026082:Singlet Oxygen
keywords: Photodynamic therapy; Photosensitizer; Singlet oxygen; Validation