Influence of the atmosphere conditions in the structure, properties and solubility of fluorine-substituted hydroxyapatites

Rivas, Manuel; Valle, Luís J. del; Turón, Pau; Puiggalı́, Jordi; Alemán, Carlos

doi:10.1016/j.matchemphys.2019.01.040

Cited by 10 publications

(5 citation statements)

References 50 publications

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“…Moreover, this interpretation is consistent with the fact that the formation of new phases is more pronounced in HAp(w), in which more vacancies are created because of the more abundant presence of OH – groups. Also, the key role of OH – groups is fully consistent with recent experimental observations on fluorine-substituted HAp (xF-HAp) and fluorapatite (FAp) . Samples sintered and thermally polarized using the same conditions as that in the present work showed that the amount of vacancies decreases with increasing fluorination degree because defluorination is much more difficult than dehydroxylation.…”

Section: Resultssupporting

confidence: 91%

“…Also, the key role of OH − groups is fully consistent with recent experimental observations on fluorine-substituted HAp (xF-HAp) and fluorapatite (FAp). 41 Samples sintered and thermally polarized using the same conditions as that in the present work showed that the amount of vacancies decreases with increasing fluorination degree because defluori- nation is much more difficult than dehydroxylation. Such results evidenced that xF-HAp and, especially, FAp are much less affected by thermal and electrical treatments than HAp.…”

Section: ■ Results and Discussionsupporting

confidence: 58%

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Electrically Polarized Hydroxyapatite: Influence of the Polarization Process on the Microstructure and Properties

et al. 2019

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Semipermanently polarized hydroxyapatite, named SP/HAp(w), is obtained by applying a constant dc electric field of 1–10 kV/cm at 300–850 °C to the samples previously sintered in water vapor, while permanently polarized hydroxyapatite, PP/HAp(a), is produced by applying a dc electric field of 3 kV/cm at 1000 °C to the samples sintered in air. SP/HAp(w) has been used for biomedical applications, while PP/HAp(a) has been proved to be a valuable catalyst for N2 and CO2 fixation. In this work, structural differences between SP/HAp(w) and PP/HAp(a) have been ascertained using Raman microscopy, wide-angle X-ray diffraction, scanning electronic microscopy, high-resolution transmission electron microscopy, and grazing incidence X-ray diffraction. Results prove the existence of crystal distortion in the form of amorphous calcium phosphate and β-tricalcium phosphate (β-TCP) phases close to the surface because of the atmosphere used in the sintering process. The existence of an amorphous layer in the surface and the phase transition through β-TCP of SP/HAp(w) are the structural factors responsible for the differences with respect to PP/HAp(a). Moreover, a superstructure has been identified in PP/HAp(a) samples, which could be another structural factor associated with enhanced conductivity, permanent polarization, and catalytic activity of this material.

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Section: Resultssupporting

confidence: 91%

Section: ■ Results and Discussionsupporting

confidence: 58%

Electrically Polarized Hydroxyapatite: Influence of the Polarization Process on the Microstructure and Properties

et al. 2019

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“…For the samples, the characteristic peaks of Ca 2p, P 2p, O 1s, and Eu 3d were all detected. Moreover, with the increase of the fluorine substitution ratio, the characteristic peak of F 1s was enhanced gradually, which indicates that the F − ions entered into the apatite lattice ( Figure 3B) [27]. When the Fions entered into the apatite lattice, the binding energy of the atom varied due to the change in chemical environments, corresponding to a shift of the peak position in the XPS spectrum.…”

Section: Morphology Observationmentioning

confidence: 96%

Effect of the Fluorine Substitution for –OH Group on the Luminescence Property of Eu3+ Doped Hydroxyapatite

et al. 2020

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In this study, different fluoridated hydroxyapatite doped with Eu3+ ion nanoparticles were prepared by the hydrothermal method. The relationship between luminescence enhancement of Eu3+ ions and a fluorine substitution ratio for hydroxyl group in hydroxyapatite was discussed. Moreover, the effect of fluorine substitution for a hydroxyl group on phase composition, crystallinity, and crystal size was studied. Phase composition and chemical structures were identified by X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) Spectroscopy analyses. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) patterns were performed to analyze the morphology and particle size. X-ray Photoelectron Spectroscopy (XPS) patterns were observed to analyze fluorine substitution for the hydroxyl group and chemical state of Eu3+ ions in fluoridated hydroxyapatite. The results of these experiments indicated that the samples with a different fluorine substitution ratio were prepared successfully by maintaining the apatite structure. With an increasing fluorine substitution ratio, the morphology maintained a rod-like structure but the aspect ratio tended to decrease. XPS patterns displayed that the fluorine replaced the hydroxyl group and brought environmental variation. The fluorine ions could affect the crystal field environment and promote luminescence conversion. There was a linear relationship between the fluorine substitution ratio and luminescence enhancement.

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“…At lower degrees of fluoridation, the solubility of the HAp is reduced [ 25 ]. Some researchers have thoroughly investigated the mechanism by which fluoride reduces the solubility of hydroxyapatite [ 26 , 27 ]. Various synthesis approaches of F doped HA are known, like the mechanochemical process [ 21 ], sol-gel [ 28 ], the hydrothermal method [ 29 ], and precipitation [ 30 ].…”

Section: Introductionmentioning

confidence: 99%

Citric Acid-Mediated Microwave-Hydrothermal Synthesis of Mesoporous F-Doped HAp Nanorods from Bio-Waste for Biocidal Implant Applications

Karunakaran

Cho

Kumar³

et al. 2022

Nanomaterials

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In this current research, mesoporous nano-hydroxyapatite (HAp) and F-doped hydroxyapatite (FHAp) were effectively obtained through a citric acid-enabled microwave hydrothermal approach. Citric acid was used as a chelating and modifying agent for tuning the structure and porosity of the HAp structure. This is the first report to use citric acid as a modifier for producing mesoporous nano HAp and F-doped FHAp. The obtained samples were characterized by different analyses. The XRD data revealed that F is incorporated well into the HAp crystal structure. The crystallinity of HAp samples was improved and the unit cell volume was lowered with fluorine incorporation. Transmission electron microscopy (TEM) images of the obtained samples revealed that a nano rod-like shape was obtained. The mesoporous structures of the produced HAp samples were confirmed by Brunauer–Emmett–Teller (BET) analysis. In vivo studies performed using zebrafish and C. elegans prove the non-toxic behavior of the synthesized F doped HAp samples. The obtained samples are also analyzed for antimicrobial activity using Gram-negative and Gram-positive bacteria, which are majorly involved in implant failure. The F doped samples revealed excellent bactericidal activity. Hence, this study confirms that the non-toxic and excellent antibacterial mesoporous F doped HAp can be a useful candidate for biocidal implant application.

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Influence of the atmosphere conditions in the structure, properties and solubility of fluorine-substituted hydroxyapatites

Cited by 10 publications

References 50 publications

Electrically Polarized Hydroxyapatite: Influence of the Polarization Process on the Microstructure and Properties

Electrically Polarized Hydroxyapatite: Influence of the Polarization Process on the Microstructure and Properties

Effect of the Fluorine Substitution for –OH Group on the Luminescence Property of Eu3+ Doped Hydroxyapatite

Citric Acid-Mediated Microwave-Hydrothermal Synthesis of Mesoporous F-Doped HAp Nanorods from Bio-Waste for Biocidal Implant Applications

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