X-Ray Diffraction and Multifrequency EPR Study of Radiation-Induced Room Temperature Stable Radicals in Octacalcium Phosphate

Shurtakova, D. V.; Yavkin, Boris; Mamin, G. V.; Orlinskii, S. B.; Сиротинкин, В. П.; Fedotov, A. Yu.; Shinkarev, A. A.; Antuzevičš, Andris; Smirnov, Igor; Tovtin, V. I.; Starostin, E. E.; Gafurov, Marat; Komlev, V. S.

doi:10.1667/rade-20-00194.1

Cited by 6 publications

(9 citation statements)

References 55 publications

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“…It may serve as additional proof to the conclusion made in ref. [54] that, in contrast to HA, the radiation-induced radicals in OCP are stabilized not in the apatite, but in the hydrated layers of OCP.…”

Section: Epr Spectroscopymentioning

confidence: 86%

“…Only one broad signal for 31 P is detected, which can be simulated as a convolution of Gaussian and Lorentzian lines with the line widths of 1.6 MHz and 0.4 MHz; however, in HA, a 31 P splitting of 0.5-1.0 MHz can be observed [35,36,58]. The absence of well-structured ENDOR and ESEEM signals from phosphorous and hydrogen nuclei may be explained by the irregularity of the incorporation of several distinct (R1-R3) defects [54] into the lattice (it is either because of preferential localization in the disordered hydrated layer or due to a large variety of incorporation sites in the apatite layer). Most probably, in line with the discussion on the EPR parameters given above, this means that the radical(s) are not located in the majority of apatite crystallites (A-or B-type substitution) but in the hydrated layers [61].…”

Section: Hyperfine Interaction Spectroscopy (Eseem and Endor Methods)mentioning

confidence: 93%

“…The duration of sample irradiation was 15 and 90 min at an electron beam current of 4 µA, with the estimated absorbed doses of about 4 and 25 kGy, respectively. The details of irradiation are provided in our paper [54].…”

Section: Methodsmentioning

confidence: 99%

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Radiation-Induced Stable Radicals in Calcium Phosphates: Results of Multifrequency EPR, EDNMR, ESEEM, and ENDOR Studies

et al. 2021

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This article presents the results of a study of radiation-induced defects in various synthetic calcium phosphate (CP) powder materials (hydroxyapatite—HA and octacalcium phosphate—OCP) by electron paramagnetic resonance (EPR) spectroscopy at the X, Q, and W-bands (9, 34, 95 GHz for the microwave frequencies, respectively). Currently, CP materials are widely used in orthopedics and dentistry owing to their high biocompatibility and physico-chemical similarity with human hard tissue. It is shown that in addition to the classical EPR techniques, other experimental approaches such as ELDOR-detected NMR (EDNMR), electron spin echo envelope modulation (ESEEM), and electron-nuclear double resonance (ENDOR) can be used to analyze the electron–nuclear interactions of CP powders. We demonstrated that the value and angular dependence of the quadrupole interaction for 14N nuclei of a nitrate radical can be determined by the EDNMR method at room temperature. The ESEEM technique has allowed for a rapid analysis of the nuclear environment and estimation of the structural positions of radiation-induced centers in various crystal matrices. ENDOR spectra can provide information about the distribution of the nitrate radicals in the OCP structure.

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Section: Epr Spectroscopymentioning

confidence: 86%

Section: Hyperfine Interaction Spectroscopy (Eseem and Endor Methods)mentioning

confidence: 93%

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Radiation-Induced Stable Radicals in Calcium Phosphates: Results of Multifrequency EPR, EDNMR, ESEEM, and ENDOR Studies

et al. 2021

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“…Radiation-induced signals in OCP (Figure ) are the most complicated among the considered CaPs and can be ascribed to the presence of three paramagnetic centerstwo nitrogen-containing and one carbonate-based radiation-induced paramagnetic centers. Their parameters are listed in Table .…”

Section: Resultsmentioning

confidence: 99%

“…It can be seen that T M in OCP is systematically lower than that in HA or TCP. It is connected with the difference in the structure of the considered CaPs as well as by the overlapping of various radiation-induced centers in OCP 67. For carbonate radicals in biogenic HA, we found that T 1 = 15−20 μs and T M = 0.7−2.0 μs.In a paper,32 we have noticed that introduction of fastrelaxing Mn 2+ ions even in low concentrations only slightly influences the line widths of the nitrate EPR spectrum but significantly shortens the transverse relaxation times or T M of nitrates (Figure10a).…”

mentioning

confidence: 95%

Study of Electron–Nuclear Interactions in Doped Calcium Phosphates by Various Pulsed EPR Spectroscopy Techniques

et al. 2021

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Substituted calcium phosphates (CaPs) are vital materials for the treatment of bone diseases and repairing and replacement of defects in human hard tissues. In this paper, we present some applications of the rarely used pulsed electron paramagnetic resonance (EPR) and hyperfine interaction spectroscopy approaches [namely, electron spin-echo envelope modulation (ESEEM) and electron–electron double-resonance detected nuclear magnetic resonance (EDNMR)] to investigate synthetic CaPs (hydroxyapatite, tricalcium, and octacalcium phosphate) doped with various cations (Li+, Na+, Mn2+, Cu2+, Fe3+, and Ba2+). These resonance techniques provide reliable tools to obtain unique information about the presence and localization of impurity centers and values of hyperfine and quadrupole tensors. We show that revealed in CaPs by EPR techniques, radiation-induced stable nitrogen-containing species and carbonate radicals can serve as sensitive paramagnetic probes to follow CaPs’ structural changes caused by cation doping. The most pulsed EPR, ESEEM, and EDNMR spectra can be detected at room temperature, reducing the costs of the measurements and facilitating the usage of pulsed EPR techniques for CaP characterization.

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Models of the Impurity Nitrogen Centers in Octacalcium Phosphate from the Density Functional Theory Calculations

Shurtakova,

Mamin,

Petrakova

et al. 2024

Arab J Sci Eng

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X-Ray Diffraction and Multifrequency EPR Study of Radiation-Induced Room Temperature Stable Radicals in Octacalcium Phosphate

Cited by 6 publications

References 55 publications

Radiation-Induced Stable Radicals in Calcium Phosphates: Results of Multifrequency EPR, EDNMR, ESEEM, and ENDOR Studies

Radiation-Induced Stable Radicals in Calcium Phosphates: Results of Multifrequency EPR, EDNMR, ESEEM, and ENDOR Studies

Study of Electron–Nuclear Interactions in Doped Calcium Phosphates by Various Pulsed EPR Spectroscopy Techniques

Models of the Impurity Nitrogen Centers in Octacalcium Phosphate from the Density Functional Theory Calculations

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