Electron spin resonance study of irradiated bone and its constituents

Termine, John D.; Pullman, I.; Posner, Aaron S.

doi:10.1016/0003-9861(67)90201-9

Cited by 46 publications

(10 citation statements)

References 31 publications

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“…In the region of g = 2.0, three paramagnetic species of CO~ [14], PO42- [8,15], and E-center [14] appear. Among them the COy radical ion is known to originate from the carbonate adsorbed on the surface of the crystal, i.e., surface carbonate [14].…”

Section: Resultsmentioning

confidence: 98%

ESR and IR studies of carbonate-containing hydroxyapatites

et al. 1982

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Synthetic carbonate-containing and carbonate-free hydroxyapatites(CO3-HA and CO3-free HA) have been investigated using ESR and IR absorption, together with X-ray diffraction and chemical analyses. Comparison of the IR spectra between 13C-enriched 13CO3-HA and 12CO3-HA prepared at 100 degrees C and at high pH suggested that the carbonate substitutes for PO4 but not for HPO4. The substitution of CO3 for PO4 in this case resulted in elimination of hydroxyl ions in a hexad axis. The elimination of hydroxyl ions was found to be related to the decrease in crystallinity for the c-axis direction, although so far there has been no direct evidence for the existence of hydroxyl deficiencies. In the case of CO3-free HAs prepared at 80 degrees, 60 degrees, 40 degrees, and 20 degrees C, the decrease in crystallinity accompanied by the decrease in the temperature for preparation was associated with the decrease in crystal size, and no significant elimination of hydroxyl ions would be expected in the absence of the carbonate.

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Section: Resultsmentioning

confidence: 98%

ESR and IR studies of carbonate-containing hydroxyapatites

et al. 1982

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“…Recently, Doi et al [8] have proposed, on the basis of a careful study on the temperature dependence of the intensities of ESR signals which are directly related to the mineral and organic constituents [7,9], that a spin energy transfer is present between them in bone, but not in enamel. They have concluded that the central signal, which is related to the mineral constituents, must be ascribed to a "~trapped-electron'" center.…”

Section: ]mentioning

confidence: 99%

“…Two sharp resonance signals, with a splitting of 501.7 gauss, can be attributed to hydrogen reso- A plot of the signal intensities P,, P~, E, and H as a function of the microwave amplitude which is proportional to square root of microwave power. P~< Numbers t • ','4 and x 2) indicate relative gains of spectrometer amplifier nances like those found in unheated ACP [9] and other calcium phosphates [6,7,15]. A single resonance signal, which is designated by the symbol E, appears with g = 2.0005 and a width between extreme points of AH = 4.4 gauss in place of the hyperfine doublet of the PO]-ion radical, which is the dominant species in the ESR spectrum of the unheated ACP (a very weak signal at magnetic field of about 3240 gauss may correspond to the low field component of the PO] hyperfine doublet).…”

Section: Electron Spin Resonancementioning

confidence: 99%

Analysis of electron-excess and electron-deficient centers in x-ray-irradiated tricalcium phosphates by electron spin resonance spectroscopy

et al. 1979

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Summary. After X-ray irradiation, new paramagnetic centers were observed in electron spin resonance (ESR) spectra of amorphous calcium phosphate (ACP) and Mg-containing tricalcium phosphate (Mg-TCP) when they were heated at 900~ for 1 h before irradiation. Heated ACP shows a single resonance signal at g = 2.0005 in place of the hyperfine doublet of the PO]-ion radical, which is the dominant species in the ESR spectrum of unheated ACP. A similar signal is observed in the heated Mg-TCP. Treatment with electron scavengers (Pb 2+ and Cd z+) and hole scavengers (Ce ~+) suggests that the single resonance signal can be ascribed to a trapped electron. Comparison between the ESR spectra before and after annealing indicates that in the case of the heated ACP such a signal is most likely connected with a localized unpaired electron close to the calcium; on the other hand, in the case of the heated Mg-TCP the signal is connected with the localized electron close to the magnesium.In addition, new sets of signals are observed in those heated samples. Their hyperfine splittings are 612 and 713 gauss for the heated ACP, and 589 and 683 gauss for the heated Mg-TCP. Those new sets of signals are found to be ascribed to the trapped holes close to two magnetically distinct sites of phosphorus nuclei in the crystal lattice of fl-tricalcium phosphate.Treatment with deuterium oxide strongly indicates that hydrogen atoms originate from adsorbed water molecules, although their half-life is a matter of months even at room temperature.

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“…In the past, biological as well as synthetically prepared carbonated apatites have been invesfigated intensively with EPR [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Afler X-or y-irradiation of these apatites, strong and complex EPR signals were detected in the region around g = 2.…”

Section: Introduetionmentioning

confidence: 99%

31P and1H powder ENDOR study of ozonide radicals in carbonated apatites, synthesized from aqueous solutions

Doorslaer¹,

Moens²,

Callens³

et al. 1996

Appl. Magn. Reson.

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An O;-defect in Na * and CO~-containing apatite powder has been invesfigated with ENDOR after X-irradiation. The powder, synthesized by a hydrolysis of octo-ca[ciurnphosphate (OCP) and NaaCO 3 was dried at 25~ untit eonstant weight was reached. At low temperatures, both 3~p and ~H ENDOR spectra were recorded for different settings of the magnetic field (i.e., when the magnetic field [s swept through the EPR O 3-spectrum). The ENDOR powder spectra were thoroughly analyzed using computer simulations based on the "orientation selection principle". Interact[ons with two types of protons and two types of np nuclei could be resolved. In this way, a detailed model could be established for the O 3-ion in the hydroxyapatite lattiee. The defect is located between two successive vacant hydroxyl sites. The axis eonnecting the two outer oxygen atoms (gy-axis) of the O3-ion is found to be a|ong the hexagonal c-axis of the lattice. The twofo|d axis of the defect ion (gz-axis) is paral[el to the b-axis of the lattiee. IntroduetionHydroxyapatite, Cat0(PO4)6(OH)2, forros the basic mineral of caleified tissues, such as dental enamel, bone and renal stone. In the past, biological as well as synthetically prepared carbonated apatites have been invesfigated intensively with EPR [1-17]. Afler X-or y-irradiation of these apatites, strong and complex EPR signals were detected in the region around g = 2. Soon it became clear that the observed EPR signals were composite, i.e., they consist of several contributions arising from radicals differing in both tocation (hydroxyl (A-type), phosphate (B-type) or surface site location) and molecular structure (CO3, CO3 3-,

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Electron spin resonance study of irradiated bone and its constituents

Cited by 46 publications

References 31 publications

ESR and IR studies of carbonate-containing hydroxyapatites

ESR and IR studies of carbonate-containing hydroxyapatites

Analysis of electron-excess and electron-deficient centers in x-ray-irradiated tricalcium phosphates by electron spin resonance spectroscopy

31P and1H powder ENDOR study of ozonide radicals in carbonated apatites, synthesized from aqueous solutions

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