Study of radiation-induced stable radicals in synthetic octacalcium phosphate by pulsed EPR

Shurtakova, D. V.; Yavkin, Boris; Gafurov, Marat; Mamin, G. V.; Orlinskii, S. B.; Kuznetsova, L. M.; Бахтеев, С А; Ignatyev, Igor S.; Smirnov, Igor; Fedotov, A. Yu.; Комлев, В. С.

doi:10.26907/mrsej-19105

Cited by 7 publications

(7 citation statements)

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“…It was concluded that in the irradiated HA samples, EPR is mainly due to the stable NO 2− 3 ions, preferably substituting one distinct PO 3− 4 position in the HA structure (substitution of the B-type), while there are several non-equivalent positions for the nitrate radical in the OCP structure. In our paper [55], we found that the distribution of A ⊥ for TCP is larger than that of the HA. We suggested that it could be due to the three different positions for PO 4 group substitution in the TCP structure, as well as due to the various mechanisms for charge compensation.…”

Section: Epr Spectroscopymentioning

confidence: 61%

“…The shape of the EPR line and the splitting values for HA and OCP are very different. This may be due to the different atomic environments, the degree of distortion of the crystal lattice, or the level of delocalization of the paramagnetic center [55]. Differences in the parameters of the Spin-Hamiltonian should be useful for further analysis of crystal structures of samples doped with various cations.…”

Section: Epr Spectroscopymentioning

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: 61%

Section: Epr Spectroscopymentioning

confidence: 99%

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

et al. 2021

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“…In a number of our previous works, it was shown that the spectroscopic and relaxation parameters of the stable NO 3 2– radicals in various calcium phosphates are extremely sensitive to changes in their local environment like the introduction of cations and anions, the transition from microsize to nanoscale samples, the phase transition to other types of calcium phosphate, etc. ,,− This allows the use of NO 3 2– as a sensitive paramagnetic probe. In this paper, we decided to trace how the introduction of a nonparamagnetic trivalent aluminum cation affects the EPR characteristics of this probe.…”

Section: Resultsmentioning

confidence: 99%

Influence of Al on the Structure and in Vitro Behavior of Hydroxyapatite Nanopowders

et al. 2019

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Nanopowders of aluminum-substituted (0−20 mol %) hydroxyapatite (HA) with the average size of 40−60 nm were synthesized by the precipitation method from nitrate solutions. A series of samples were studied by various analytical tools to elucidate the peculiarities of Al introduction. Electron paramagnetic resonance and pulsed electron-nuclear double resonance data demonstrate that incorporation of Al resulted in a decrease in the concentration of impurity carbonate anions and lead to an increase in the number of protons in the distant environment of the impurity nitrogen species. Density functional theory calculations show that the Al 3+ incorporation is accompanied by the local positional rearrangement and the distortion of anion channel geometry. An in vitro test conducted on MG-63 cells demonstrates the cytocompatibility and magnification of the surface matrix characteristics with Al doping.

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“…It was concluded that in the irradiated HA samples, EPR is mainly due to the stable NO 3 2− ions (I = 1 for 14 N nuclei) preferably substituting the PO 4 3− position in the HA structure (substitution of the B-type). 30 In our paper, 34 we have found that for NO 3 2− in TCP, the distribution of A ⊥ is larger than that for HA. We have suggested that it could be due to three different positions for PO 4 group substitution in the TCP structure as well as due to the various schemes for charge compensation.…”

Section: Epr Ofmentioning

confidence: 99%

“…One of the analytical nondestructive methods for studying CaPs of biogenic and synthetic origins is electron paramagnetic resonance (EPR). − ,− Pure, nonsubstituted CaPs (Table ) are EPR-silent. Consequently, conventional EPR can be used for the purity check of CaP materials (e.g., for the presence of metal impurities) …”

Section: Introductionmentioning

confidence: 99%

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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Study of radiation-induced stable radicals in synthetic octacalcium phosphate by pulsed EPR

Cited by 7 publications

References 0 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

Influence of Al on the Structure and in Vitro Behavior of Hydroxyapatite Nanopowders

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

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