title: Susceptibility of calcium-deficient hydroxyapatite-collagen composite to irradiation.
abstract: The ESR spectrum of calcium-deficient hydroxyapatite (DAp) has the peaks assigned to the hyperfine structure of dangling H+ (hyperfine coupling constant = 50.8 mT, I = 1/2) due to the HPO(4)2- ion which captured the hole released by X ray irradiation. This ESR peak intensity in DAp with collagen (c-DAp) decreased in an increase in the amount of collagen added into Ca(H2PO4)2H2O (MCP) electrolytic solution, because dangling H+ of HPO(4)2- binds to the carboxyl group of collagen due to the hydrogen bond. The ESR signal intensities at near g = 2 in DAp, c-DAp, and stoichiometric hydroxyapatite (HAp) after X ray irradiation, were proportional to the absorbed dose in the range from 6 to 380 Gy. These ESR signal intensities decreased when the X ray-irradiated DAp, c-DAp, and HAp was suspended in the simulated body fluid. This fact suggests that the surface layer contained high density of ESR active species in DAp, c-DAp, and HAp dissolved in the simulated body fluid. Therefore, with the dosemeter utilising such biomaterials as tooth and bone, sufficient care must be paid to the effect of body fluid.
authors.affiliation: Department of Material Science and Technology, Faculty of Engineering, Niigata University, Japan. mohta@eng.niigata-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Ohta
authors.forename: M
authors.initials: M
authors.lastname: Yasuda
authors.forename: H
authors.initials: H
authors.lastname: Okamura
mesh_terms: D003094:Collagen / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D012996:Solutions; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D012996:Solutions; D003094:Collagen; D017886:Durapatite