Pb3+ radiation defects in Ca9Pb(PO4)6(OH)2 hydroxyapatite nanoparticles studied by high-field (W-band) EPR and ENDOR

Yavkin, Boris; Mamin, G. V.; Orlinskiĭ, S. B.; Gafurov, Marat; Салахов, М. Х.; Biktagirov, Timur; Климашина, Е. С.; Putlayev, V.I.; Tret’yakov, Yu. D.; Silkin, N. I.

doi:10.1039/c2cp23601j

Cited by 30 publications

(27 citation statements)

References 31 publications

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“…Then, the precipitates were filtered, thoroughly washed with 1 l of distilled water and allowed to dry at room temperature (RT) overnight. Other details of the synthesis and post-synthesis treatments are given in [17,18]. 55…”

Section: Synthesis Of Hap Powdersmentioning

confidence: 99%

Nitrogen-containing species in the structure of the synthesized nano-hydroxyapatite

et al. 2014

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Synthesized by the wet chemical precipitation technique hydroxyapatite powders (HAp) with the sizes of the crystallites of (20-10 50) nm and 1 m were analyzed by multi-frequency (9 and 95 GHz) electron paramagnetic resonance (EPR) methods. It is shown that during the synthesis process nitrate anions from the reagents (by-products) could incorporate into the HAp structure. The relaxation times and EPR parameters of the axially symmetric NO 3 2paramagnetic centers detected after X-ray irradiation of the product at room temperature are measured with high accuracy. Assignments of the observed EPR spectra as compared with that given in literature are discussed. Analyses of electron-nuclear double resonance (ENDOR) data from 1 H and 31 P nuclei and ab-15 initio density functional theory (DFT) calculations allow suggesting that the paramagnetic centers and nitrate anions as the precursors of NO 3 2radicals preferably occupy PO 4 3site in the HAp structure. 65 110 Troullier-Martins pseudopotentials [27] with the plane-wave cutoff energy of 70 Ry.

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Section: Synthesis Of Hap Powdersmentioning

confidence: 99%

Nitrogen-containing species in the structure of the synthesized nano-hydroxyapatite

et al. 2014

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“…Nevertheless, to date one can state that, regardless of the nature of AP calcification, its assessment to predict complications for the cardiovascular system turned to be higher than the traditional approaches to risk analysis. We hope that our further research by using the presented and the more advanced EPR approaches like electron-nuclear double resonance (ENDOR, [17, 21]) would allow for finding either positive or negative correlation between the status of AP and Mn 2+ environment in the conditions of the micro- and macrocalcifications.…”

Section: Discussionmentioning

confidence: 99%

“…Lomonosov Moscow State University, Moscow, Russia). Details of the synthesis and HAp characterization are given in [17, 20, 21]. …”

Section: Methodsmentioning

confidence: 99%

“…In a series of our previous papers [17–21], we mainly focused on the investigation of the natural and synthetic nano- and micropowders of HAp with the substitution by different ions and groups (lead, manganese, carbonates, nitrogen containing species) in the large concentration range of 0.001–14.0 wt% as well as on the comparison of the results acquired on the model systems with those obtained from the postmortem clinical material [6, 7]. We have gathered the experience of the characterization of HAp and AP samples by different EPR techniques to choose the more sensitive high-field (HF) EPR (W-band, magnetic field B 0 of about 3.4 T) which requires the substance grain size with the cross-sectional diameter of less than 1 mm.…”

Section: Introductionmentioning

confidence: 99%

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Paramagnetic Manganese in the Atherosclerotic Plaque of Carotid Arteries

Chelyshev

Gafurov

Ignatiev

et al. 2016

BioMed Research International

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The search for adequate markers of atherosclerotic plaque (AP) instability in the context of assessment of the ischemic stroke risk in patients with atherosclerosis of the carotid arteries as well as for solid physical and chemical factors that are connected with the AP stability is extremely important. We investigate the inner lining of the carotid artery specimens from the male patients with atherosclerosis (27 patients, 42–64 years old) obtained during carotid endarterectomy by using different analytical tools including ultrasound angiography, X-ray analysis, immunological, histochemical analyses, and high-field (3.4 T) pulse electron paramagnetic resonance (EPR) at 94 GHz. No correlation between the stable and unstable APs in the sense of the calcification is revealed. In all of the investigated samples, the EPR spectra of manganese, namely, Mn2+ ions, are registered. Spectral and relaxation characteristics of Mn2+ ions are close to those obtained for the synthetic (nano) hydroxyapatite species but differ from each other for stable and unstable APs. This demonstrates that AP stability could be specified by the molecular organization of their hydroxyapatite components. The origin of the obtained differences and the possibility of using EPR of Mn2+ as an AP stability marker are discussed.

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“…They include semiempirical and first-principles calculation methods to extract the phonon related quantities [2][3][4]. Due to the complexity of the chemistry of HAp, there remain apparent discrepancies and contradictions between calculations and experimental results (see [5], for example). Verifications and refinements of the exploiting models should be done and new approaches for the extracting the macroscopic parameters from the computational models should be introduced.…”

Section: Introductionmentioning

confidence: 99%

Phonon Spectrum in Hydroxyapatite: Calculations and EPR Study at Low Temperatures

et al. 2015

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Density functional theory based calculations within the framework of the plane-wave pseudopotential approach are carried out to define the phonon spectrum of hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 (HAp). It allows to describe the temperature dependence of the electronic spin-lattice relaxation time T 1e of the radiation-induced stable radical NO 3 2-in Hap, which was measured in X-band (9 GHz, magnetic field strength of 0.34 T) in the temperature range T = (10-300) K. It is shown that the temperature behavior of T 1e at T > 20 K can be fitted via two phonon Raman type processes with the Debye temperature D 280 K evaluated from the phonon spectrum.

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Pb3+ radiation defects in Ca9Pb(PO4)6(OH)2 hydroxyapatite nanoparticles studied by high-field (W-band) EPR and ENDOR

Abstract: W-band pulsed EPR and ENDOR investigations of X-ray irradiated nanoparticles of synthetic hydroxyapatite Ca(9)Pb(PO(4))(6)(OH)(2) are performed. It is shown that in the investigated species lead ions probably replace the Ca(1) position in the hydroxyapatite structure.

Cited by 30 publications

References 31 publications

Nitrogen-containing species in the structure of the synthesized nano-hydroxyapatite

Nitrogen-containing species in the structure of the synthesized nano-hydroxyapatite

Paramagnetic Manganese in the Atherosclerotic Plaque of Carotid Arteries

Phonon Spectrum in Hydroxyapatite: Calculations and EPR Study at Low Temperatures

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