Hydroxyapatite micro- and nanoparticles: Nucleation and growth mechanisms in the presence of citrate species

Martins, Manuel A.; Santos, Catarina; Almeida, Margarida; Costa, Maria Elisabete V.

doi:10.1016/j.jcis.2007.10.008

Cited by 165 publications

(149 citation statements)

References 28 publications

Supporting

Mentioning

134

Contrasting

Unclassified

Order By: Relevance

“…These results are corroborated by several experimental studies of the nucleation and growth mechanisms of HAP NPs in the presence of various compositions of the solution, such as citrate species [45] or nonionic surfactants [46]. These results correlate with recent HAP studies, showing that the basic inorganic building blocks of bones and teeth are nanocrystalline and NPs combined into self-assembly structures under the control of bioorganic matrices [17].…”

Section: Figsupporting

confidence: 82%

“…As it was shown in [31,32,45], in the former case after synthesis and growth of HAP in the presence of citrates the HAP nanorods were short of the length of ~ 100 nm, while in the latter case the nanorods were longer of length up to ~ 1000 nm. Therefore, it was shown that citrates stabilize the HAP surfaces and shapes (due to their charges, just as hydrogen charges or protons influenced HAP NPs shape [31,32]).…”

Section: Main Principles and Features Of Hap Surfaces Charges And Elmentioning

confidence: 62%

“…From experimental studies of the influence of citrates on the HAP nano-crystals formation it is known now, that for different contents of citrate molecules in the initial starting solution for precipitation of HAP, in the course of growth the HAP structure acquires different sizes, lattice's parameters and shapes [30,45]. The data obtained show clearly the positioning of interacting sites on the HAP surface and allow us to propose a mechanism for the formation of various HAP nanostructure shapes under the influence of negatively charged citrate quantities.…”

Section: Main Principles and Features Of Hap Surfaces Charges And Elmentioning

confidence: 99%

See 2 more Smart Citations

Компьютерные Исследования Наноструктур Гидроксиапатита, Их Особенности И Свойства

Bystrov¹

2017

Math.Biol.Bioinf.

View full text Add to dashboard Cite

Abstract. In this review paper the main approaches to modeling the hydroxyapatite (HAP) structures and first-principle calculations of their properties, pure and with various defects, are considered. First, the HAP nano-particles (NPs) and clusters peculiarities are described using different methods: molecular mechanical and quantum mechanical, especially semi-empirical such as PM3. Both approximations used here, namely, restricted Hartee-Fock (RHF) and unrestricted Hartee-Fock (UHF), are considered. The influence of the protons (hydrogens), contained in the surrounding medium (pH), on the formation of HAP nanoparticles of various sizes and shapes is considered and discussed. Second, the HAP crystal unit cells studies are considered on the basis of a density functional theory (DFT) modelling. The main peculiarities of both phases (hexagonal and monoclinic) are considered too, including their ordered and disordered substructures. One of the important aspects of the computer modeling of HAP is to build the models and consider various structural modifications of HAP (such as, vacancies of oxygen atoms and hydroxyl OH group, hydrogen interstitials and different substitutions of atoms in HAP unit cell), which allow explicitly creating and exploring the changes in the charges of HAP and the electrical potential on the HAP surface. HAP modifications are most close to biological HAP and therefore are necessary for implant medical applications and can create and functionalize HAP surface with most adhesive properties for living cells (osteoblasts, osteoclatst). This improves the HAP implant quality. Besides, it has recently been established that oxygen vacancy in HAP influences their photo-catalytic properties. It is important for HAP usage as in environmental remediation and for bacteria inactivation. Therefore it is very important to create and investigate the oxygen vacancy models in HAP, and others defects models. In this work we review a DFT modelling and studies of HAP, both pure perfect bulk and imperfect bulk cases. Special HAP modelling approaches are used for layered slab super-cells units, which include vacuum spaces between the layered slabs forming HAP surface. To all these computer studies the first principle calculations were applied. In this review various DFT approximations are analysed for bulk and surface modified HAP. These approximations are carried out using both the local basis (local density approximation -LDA, in AIMPRO codes) and the plane-waves (generalized gradient approximation -GGA, in VASP codes). Data of all structures and models of HAP defects investigated are widely analyzed.

show abstract

Section: Figsupporting

confidence: 82%

Section: Main Principles and Features Of Hap Surfaces Charges And Elmentioning

confidence: 62%

Section: Main Principles and Features Of Hap Surfaces Charges And Elmentioning

confidence: 99%

See 1 more Smart Citation

Компьютерные Исследования Наноструктур Гидроксиапатита, Их Особенности И Свойства

Bystrov¹

2017

Math.Biol.Bioinf.

View full text Add to dashboard Cite

show abstract

“…chemical precipitation method [2], hydrotermal technique [3. 4], emulsion method [5], and sol-gel process [6], mechanochemical method [7].…”

Section: Introductionmentioning

confidence: 99%

The current density of hydroxyapatite electrosynthesis by ion exchange resin chambers

et al. 2017

View full text Add to dashboard Cite

Abstract. Electrochemical method has been developed to produce hydroxyapatite (HA) powders. Synthesis of hydroxyapatite particles was carried out from a homogeneous solution. The homogeneous solution was contained of Na2H2EDTA.2H2O, KH2PO4 and CaCl2 on 0.25/0.25/0.15 M. Water reduction at cathode to form OH -ion is very substantial in formation of hydroxyapatite. The OH -ions causes the release of Ca 2+ ions and change the equilibrium phosphate for the formation reaction of HA. The problem of electrochemical method is OH -ions move away from the cathode due to the difference in charge. This condition decrease the productivity of the formation of HA because OH -ions react with H + to form H2O. In this work, we develop new method electrosynthesis of HA with 2 chambers system. The electrolysis use ion exchange resin to separate the OH -ions and H + ions formed. The effect of current density to HA product was studied. HA product analysed with XRD. We conclude that the electrosynthesis hydroxyapatite with ion exchange resin more effective than without ion exchange resin. The higher current density, the more pure HA formed.

show abstract

“…The influence of environments (pH index, citrate content, etc.) was established too [3,8] as well as the variations of HAP nanoparticle size and shape in interactions with living cells [3,4,7,8]. However, many unclear details of the mechanism remain as for formation of the surface charges, as well as of the interaction between electric charges, surface potential and living cells (osteoblasts and other osteo-cells leading to bone tissues formation) on the HAP surface.…”

Section: Introductionmentioning

confidence: 99%

Моделирование И Анализ Данных Синхроторонного Облучения Для Модифицированной Структуры Гидроксиапатита

Bystrova¹

2014

Math.Biol.Bioinf.

View full text Add to dashboard Cite

Abstract.The results are based on the first principal modeling and calculations for hydroxyapatite (HAP) nanostructures as native as well surface modified, charged and having various defects (H and OH vacancies, H internodes). HAP structures having being studied using Local Density Approximation (LDA) method with calculations of Density of States (DOS) allow us analyzing the experimental forbidden energy gap (Eg) and work function data. Molecular modeling by HyperChem is confirmed by photo-electron monochromatic measurements up to 6 eV and photo-luminescence (PL) data from synchrotron DESY experimental data up to 30 eV values. Brief analysis of the influence of heating, microwave radiation, hydrogenation, x-rays and synchrotron radiation on HAP surface is presented in this work. New data of the structure of modified hydroxyapatite are obtained. The determined energy levels for H internodes is EH-int ~ Ev + (1.5-2.0) eV, while for OH vacancy energy is in the range of EOH-vac ~ Ev + (2.9-3.4) eV inside the forbidden zone Eg. The analysis of PL emission allows us to conclude that these energies are close to observed main PL spectral line 420 nm (2.95 eV), and consequently OH vacancy could play the leading role in the surface energy levels changes and charging. But the influence of the inserted hydrogen is revealed too through excitation from most deep valence band levels due to existence of close overlapped molecular orbital with phosphorus atoms in the excited states. Both defects are observed by PL emission spectrum under synchrotron excitation energy in diapason ~8.5-14.5 eV.

show abstract

Hydroxyapatite micro- and nanoparticles: Nucleation and growth mechanisms in the presence of citrate species

Cited by 165 publications

References 28 publications

Компьютерные Исследования Наноструктур Гидроксиапатита, Их Особенности И Свойства

Компьютерные Исследования Наноструктур Гидроксиапатита, Их Особенности И Свойства

The current density of hydroxyapatite electrosynthesis by ion exchange resin chambers

Моделирование И Анализ Данных Синхроторонного Облучения Для Модифицированной Структуры Гидроксиапатита

Contact Info

Product

Resources

About