title: Fluorometry of singlet oxygen generated via a photosensitized reaction using folic acid and methotrexate.
abstract: A method for the fluorometry of singlet oxygen ((1)O(2)) using less fluorescent folic acid and its analogue, methotrexate (MTX), was examined. Folic acid and MTX were decomposed into a strongly fluorescent pteridine compound via a photosensitized reaction by (1)O(2)-generating photosensitizers in a deuterium oxide solution. The fluorescence intensity increased in proportion to the irradiation time or the number of photons absorbed by the photosensitizer. This method using the fluorescence enhancement of these folic acid analogues can be applied to determine the quantum yield of (1)O(2) generated through a photosensitized reaction in deuterium oxide. The background fluorescence of MTX is quite smaller than that of folic acid, indicating that MTX can be used for the more sensitive detection of (1)O(2).
authors.affiliation: Department of Basic Engineering (Chemistry), Faculty of Engineering, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka, 432-8561, Japan. tkhirak@ipc.shizuoka.ac.jp
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Hirakawa
mesh_terms: D017666:Deuterium Oxide / Q000737:chemistry; D005470:Fluorometry / Q000379:methods*; D005492:Folic Acid / Q000031:analogs & derivatives / Q000737:chemistry*; D008727:Methotrexate / Q000737:chemistry*; D015394:Molecular Structure; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000737:chemistry*; D011789:Quantum Theory; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D026082:Singlet Oxygen / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013997:Time Factors
chemical_list: D017319:Photosensitizing Agents; D026082:Singlet Oxygen; D005492:Folic Acid; D017666:Deuterium Oxide; D008727:Methotrexate