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Journal ArticleDOI

Accurate characterization of pure silicon-substituted hydroxyapatite powders synthesized by a new precipitation route

TL;DR: The results, particularly those from infrared spectroscopy, raise serious reservations about the phase purity of previously prepared and biologically evaluated SiHA powders, pellets and scaffolds in the literature.
About: This article is published in Acta Biomaterialia.The article was published on 2013-06-01 and is currently open access. It has received 88 citations till now. The article focuses on the topics: Infrared spectroscopy & Fourier transform infrared spectroscopy.

Summary (1 min read)

1. Introduction

  • In order to correctly describe the physical, chemical and biological properties of SiHAs and to compare them to routinely implanted HA and β-TCP, well-characterized pure SiHAs powders first need to be prepared.
  • Therefore, this work was devoted to the development of a new route to synthesize monophasic SiHA powders with controlled stoichiometry.
  • To this purpose, a solution of soluble silicate was first prepared from TEOS via a sol-gel route, and then accurate powder analysis was carried out by means of ICP/AES, Xray powder diffraction, Rietveld refinement, high resolution electron transmission microscopy (HR-TEM) with energy dispersive spectroscopy (EDS) as well as infrared (FT-IR/ATR) and solid-state NMR spectroscopy.
  • Two pH levels of precipitation were studied, as well as six Si/P molar ratios.

2.1 Powder synthesis

  • The as-synthesized powders were heated under air using an alumina crucible.
  • The heating and cooling rate was fixed at 4°C min -1 .

2.2.1 X-ray powder diffraction and Rietveld refinement

  • Crystalline phases were identified by means of a Siemens D5000 θ/2θ X-ray diffractometer.
  • The evolution of the crystallinity of the samples after calcination at 1000°C for 15 h was evaluated by means of the full width at half maximum (FWHM) of the (211) peak at 2θ=31.8°, as it had the highest intensity and minimal overlap with neighboring peaks.

2.2.4 Electron microscopy (HR-TEM, SAED and EDX)

  • Gold was then distributed as crystallized nano-domains which were used as a reference in the selected area electron diffraction (SAED) patterns to calculate as precisely as possible the lattice parameters.
  • The SAED patterns obtained from regions with or without gold on the HA part were the same.

3.2.4 Electron microscopy

  • The results are the average of about ten intervals per pattern.
  • Moreover, other experimental patterns for different zone axes (not shown here) were obtained and compared to theoretical electron diffraction patterns calculated by means of the Java Electron Microscopy Simulation (JEMS) software [87] .
  • The results indicate that the experimental and simulated patterns are perfectly superimposed for 0.734 ≥ c/a ≥ 0.729.

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Citations
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Journal ArticleDOI
TL;DR: This review discusses the current data obtained from original research in biochemistry and biomaterials science supporting the role of silicon in bone, comparing both the biological function of the element and analysing the evolution of silicon-containing biommaterials.

150 citations

Book ChapterDOI
01 Jan 2015

100 citations

Journal ArticleDOI
TL;DR: The present review is mainly focused on both the capability of HAp nanoparticles to encapsulate diverse compounds as well as the preparation methods of scaffolds incorporating HAp.
Abstract: Composites of hydroxyapatite (HAp) are widely employed in biomedical applications due to their biocompatibility, bioactivity and osteoconductivity properties. In fact, the development of industrially scalable hybrids at low cost and high efficiency has a great impact, for example, on bone tissue engineering applications and even as drug delivery systems. New nanocomposites constituted by HAp nanoparticles and synthetic or natural polymers with biodegradable and biocompatible characteristics have constantly been developed and extensive works have been published concerning their applications. The present review is mainly focused on both the capability of HAp nanoparticles to encapsulate diverse compounds as well as the preparation methods of scaffolds incorporating HAp. Attention has also been paid to the recent developments on antimicrobial scaffolds, bioactive membranes, magnetic scaffolds, in vivo imaging systems, hydrogels and coatings that made use of HAp nanoparticles.

83 citations

Journal ArticleDOI
TL;DR: This review focuses on state-of-the-art and the current advances in the development of 3D culture systems for bone biology research, and details main characteristics and challenges associated with its three main components, that is, scaffold, cells, and perfusion bioreactor systems.
Abstract: Most of our knowledge of bone cell physiology is derived from experiments carried out in vitro on polystyrene substrates However, these traditional monolayer cell cultures do not reproduce the complex and dynamic 3-dimensional (3D) environment experienced by cells in vivo Thus, there is a growing interest in the use of 3D culture systems as tools for understanding bone biology These in vitro engineered systems, less complex than in vivo models, should ultimately recapitulate and control the main biophysical, biochemical and biomechanical cues that define the in vivo bone environment, while allowing their monitoring This review focuses on state of the art and the current advances in the development of 3D culture systems for bone biology research It describes more specifically advantages related to the use of such systems, and details main characteristics and challenges associated with its three main components, ie scaffold, cells and perfusion bioreactor systems Finally, future challenges for non-invasive imaging technologies are addressed

80 citations

Journal ArticleDOI
01 Jun 2021
TL;DR: In this paper, a review summarises recent and relevant studies on cationic and anionic substitutions in the HAp lattice that are commonly found in the human body.
Abstract: Biological apatites are characterised by various ionic substitutions within the HAp lattice that are crucial for bone metabolism. The introduction of key role elements within synthetic calcium phosphates (CaP), mainly hydroxyapatite (HAp), can increase osteogenesis and enhance bone regeneration process. The lattice structure of HAp enables cationic and anionic substitutions leading to the enhanced biological performance of synthetic bone graft materials. This review summarises recent and relevant studies on cationic and anionic substitutions in the HAp lattice that are commonly found in the human body. Furthermore, co-substituted HAp obtained from synthetic and biological precursors, along with their influence on the bone regeneration process, has been discussed. Finally, future perspectives for the use of substituted HAp have been presented.

77 citations

References
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Journal ArticleDOI
TL;DR: Silicon-substituted hydroxyapatite (Si-HA) with up to 1.8% Si content was prepared successfully by a hydrothermal method, using Ca(NO3)2, (NH4)3PO4 or Si(OCH2CH3)4 (TEOS) as starting materials.

120 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe the synthesis and detailed characterisation of nanocrystalline silicon-substituted hydroxyapatite (SiHA) thin coatings applied to a titanium substrate via a magnetron co-sputtering process.
Abstract: Hydroxyapatite [Ca-10(PO4)(6)(OH)(2)], (HA) is similar in composition to bone mineral and has been found to promote new bone formation when implanted in a skeletal defect. However, its use in biomedical applications is limited by its relatively slow rate of biological interaction, and there is also a requirement to improve the success rate of HA implants in younger active patients, particularly where implants will be in place long-term. The addition of silicon (Si) into HA has been demonstrated to enhance the speed, and quality of the bone repair process. This paper describes the synthesis and detailed characterisation of nanocrystalline silicon-substituted hydroxyapatite (SiHA) thin coatings applied to a titanium substrate via a magnetron co-sputtering process. Amorphous SiHA coatings (similar to 1 mu m thick) with varying Si content up to 4.9 wt% were produced before being transformed into crystalline films by heat-treatment. The crystalline coating was characterised by X-ray diffraction (XRD) and infrared (IR) analysis, and confirmed to be a single-phase apatite. The substitution of Si into HA resulted in an increase in both the a- and c-axes of the unit cell parameters, but a decrease in the crystallite size, with increasing Si substitution. This substitution also caused a decrease in the intensities of both the O-H and P-O bands in the IR spectra. Hence, these findings confirmed that the crystal structure of HA was altered with Si substitution. In vitro cell culture work showed that these SiHA thin coatings exhibited enhanced bioactivity and biofunctionality. An increase in the attachment and growth of human osteoblast-like (HOB) cells on these coatings was observed throughout the culture period, with the formation of extracellular matrix. In addition, confocal microscopy revealed that HOBs developed mature cytoskeletons with clear evidence of actin stress fibres, along with defined cell nuclei. (c) 2006 Springer Science + Business Media, Inc.

115 citations


"Accurate characterization of pure s..." refers methods in this paper

  • ...to prove the purity of SiHA powders synthesized usi ng Gibson’s method [9, 23, 39, 40, 43, 106 44, 46, 47, 53, 57] or displaying the same new infr ared bands [14, 32, 36, 48, 50, 54, 62]....

    [...]

  • ...107 Several methods are used to prepare Si-substituted hydroxyapatites (SiHAs), such as 108 the sol-gel route [48], resuspension processes [20, 33, 34, 63-66], solid state reactions [10, 109 67], hydrothermal techniques [17, 68, 69], mechanoc hemical methods [70], magnetron 110 sputtering [14], pulsed laser deposition [51, 71], electrophoretic deposition [72] and 111 precipitation from aqueous solutions....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the preparation of silicated hydroxyapatite Ca 10 (PO 4 ) 6− x (SiO 4 ) x (OH) 2−x (SiHA) with 0⩽ x ⩽2 was investigated using a wet precipitation method followed by a heat treatment.

115 citations

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