Hydroxyl Apatite Layer Research Articles

Physical properties of (SiO2-CaCl2) doped with 3-methacryloxypropyl trimethoxysilane (MAPTMS)

In this study, TEOS - CaCl2 and Mixed TEOS-MAPTMS-CaCl2 were synthesized via sol-gel method and evaluated as a bioactive bone substitute. The hydrolysis and condensation were achieved in an (ethanol/water) solution. The ratio of silane to water to ethanol was 1:3:3. Bioactivity of the samples was premeditated via in-vitro test by inundation in simulated body fluid (SBF) to assess the creation of a hydroxyl apatite (HA) layer on the surface of the samples. Structural characterization of the prepared samples was done using Thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and fourier transform infrared (FTIR) spectroscopy. Elemental Analysis was performed using a UV-Vis Spectrophotometer. Results showed the creation of a layer of hydroxyl apatite (HA) on the surface of the samples. It was found that, sample contain hydrocarbon chain (sample doped with MAPTMS) need higher temperature to lose water and ethanol, i.e. organic precursor increases the thermal stability of the samples. In addition a layer of HA were deposited on the surfaces of the two samples after soaking in SBF for 33 days.

Preparation and Characterization of Inorganic Organic Hybrid Material Based on TEOS/MAPTMS for Biomedical Applications

In this study, inorganic-organic hybrid material consisting of tetraethyl orthosilicate (TEOS) and 3-methacryloxypropyl trimethoxysilane (MAPTMS) were prepared with sol-gel process and evaluated as a bioactive bone substitute. The hydrolysis and condensation were attained in an (ethanol/water) solution. Different molar ratios of TEOS/MAPTMS [(1:0), (1:1), (1:2), (1:3) and (1:4)] [M0, M1, M2, M3, M4] respectively were proposed. The molar proportion of silane to water to ethanol was 1:3:3. Bioactivity of all samples was studied via in-vitro test by immersion in simulated body fluid (SBF) to evaluate the creation of a calcium phosphate (CP) layer on the surface of specimens. Structural characterization of the prepared samples was performed using X -ray diffraction (XRD) and fourier transform infrared (FTIR) spectroscopy while the morphology of the samples was examined using scanning electron microscopy (SEM) equipped with an energy dispersive x-ray analysis (EDXA). Results showed the formation of a layer of hydroxyl apatite (HA) on the surface of all samples. As the polymer amount increases the nucleation sites and surface porosity increase, which improve the bioactivity of the sample surface. HA layer increased with increasing the concentration of MAPTMS.

Titanium incorporated Zinc-Phosphate bioactive glasses for bone tissue repair and regeneration: Impact of Ti4+on physico-mechanical and in vitro bioactivity

A novel glass system 8ZnO–22Na2O–(24-x)CaO–46P2O5–xTiO2 (x = 0.2, 0.4, 0.6, 0.8 and 1 mol%) was fabricated and investigated in detail for the appropriateness in the use of bone repair and regeneration applications. In this context, we explored the structural, thermal, mechanical, degradation, pH evaluation along with antibacterial assay, cytocompatability and cell proliferation by various characterization techniques like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive spectrometry (EDS) and differential thermal analysis (DTA), Vickers hardness, cell counting kit (CCK8) method and agar plates method. The obtained results of density, thermal stability and Vickers hardness increase with the increasing content of TiO2 leads to the densification of glass structure dueto formation new linkages P–O–Ti and enters into the network in the form of either TiO4 or TiO5/6 structural units. The formation of a rich crystalline hydroxyl apatite (HAp) layer on the samples with incubation time (3, 7, 14 and 21days) and content of TiO2 up to 0.6 mol% in simulated body fluid (SBF) were confirmed by in vitro analysis. Interestingly, no inhibitory effects on HAp layer formation with the addition of titanium up to 1 mol% were noticed. Lower degradation rate and pH values endorsed to hydration resistant with Ti4+ inclusion, leads to controlled ion leaching. The rat mesenchymal stem cells (rMSCs) growth on glass samples showed the enhanced biocompatibility and proliferation without toxicity. In addition, all glasses possess good antimicrobial properties against bacterial species Escherichia coli (E.coli). Finally, the results revealed that the 0.6 mol% of TiO2 glass (T.6) showed abundant performance for bone generation applications.

Impact and biocompatibility studies on Mg2+‐substituted Apatite‐derived 3D porous scaffolds for hard tissue engineering

AbstractThe objective of this study was to develop Mg2+‐substituted Apatite scaffolds by slip‐casting method. The Apatite scaffolds were prepared as engineering constructs with interconnected pore structure with a pore size of 128‐194 μm range. The physicochemical properties such as crystalline phase, functional group, microstructure, pore size distribution, and elemental compositions of the scaffolds were characterized. The bioactivity of the developed porous scaffolds was investigated in Simulated Body Fluid (SBF) for various time periods (3 and 7 days). In vitro bioactivity results confirm the hydroxyl Apatite layer formation of the scaffolds and results suggest that the developed microporous scaffold could be used as suitable candidates in bone tissue engineering.

Fabrication of graphene incorporated biphasic calcium phosphate composite and evaluation of impact of graphene in the in-vitro biomineralization process

The objective of this work is to design and development of graphene based bioceramic composite. The composition of graphene bioceramic composite is Hydroxyapatite/β-Tricalcium phosphate reinforced Graphene oxide (HAp/β-TCP/GO). The crystalline structure, chemical composition, morphology and elemental analysis of the developed composite were characterized using analytical techniques such as X-Ray Diffraction (XRD), Fourier Transform Infra red (FTIR) Spectroscopy, Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS). In order to investigate the effect of graphene oxide on the in-vitro bio mineralization, the developed composite was immersed in Simulated Body Fluid (SBF) solution for various time periods (0, 7, 14 and 21 days) and the results indicate that the reinforcement of graphene oxide promotes the growth of hydroxyl apatite layer on the surface of composite discs. Further the developed composite of β-TCP/HAp reinforced graphene oxide can be used as a potential candidate material for biomedical applications.

Enhanced antimicrobial properties of bioactive glass using strontium and silver oxide nanocomposites

ABSTRACTBioactive glass has a wide range of biomedical applications. It has attracted immense interest due to its unique ability to bond with a bone through ion exchange in simulated body fluid (SBF) when implanted inside the body. This study concerns sol-gel synthesis of a new bioactive glass composition: 55SiO2-40CaO-(5-x) SrO-xAg2O doped with different mol% of silver as an antibacterial agent, i.e. 0%, 2% and 4% AgSr(0), AgSr(2) & AgSr(3), respectively. This method is a widely used in the preparation of glass ceramics because of its low-temperature. The effect of introducing strontium in addition to silver as an antimicrobial agent into the bioglass matrix was studied. Structural studies were conducted using various techniques including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) and High-resolution transmission electron microscopy (HR-TEM). Bioactivity was investigated by in-vitro synthesis involving immersion of the samples in SBF for different time intervals. The XRD, FTIR and FE-SEM results confirmed the formation of a hydroxylapatite layer on the surface of the finally prepared bioglass materials. An antimicrobial study revealed that the prepared bioactive glass showed a significant effect on two bacteria E. coli and S. aureus.

Comparative Study of Silver Nanoparticles Coated and Uncoated NiO–Fe2O3–CaO–SiO2–P2O5 Ferromagnetic Bioactive Ceramics

Bioactive ferromagnetic ceramics of system xNiO–(3−x)Fe2O3–52CaO–30SiO2–15P2O5, (x = 0, 3 mol%) have been prepared in the laboratory using sol–gel technique. Silver nanoparticles coating has been undertaken on the surface of synthesized samples. Comparative study of silver nanoparticles coated and uncoated samples has been undertaken with the help of transmission electron microscopy, X‐ray diffraction (XRD), degradation, drug delivery, hemolysis, antimicrobial, and cell culture studies. XRD patterns indicate the growth of hydroxyl apatite layer on the surface of coated as well as uncoated samples. Ferromagnetic properties of samples have been investigated with the help of vibrating sample magnetometer technique. Samples have shown good response as drug carriers under normal conditions as well as under the influence of magnetic field. Drug release mechanism and mesoporus nature of samples have been investigated with the help of Brunauer–Emmett–Teller technique. Nonreactivity of samples (coated and uncoated) with red blood cells and white blood cells show nontoxic nature of the samples. Coated samples have shown better antimicrobial properties against six different microorganisms, including some resistive strain like methicillin‐resistant Staphylococcus aureus with minimum inhibitory concentration of 0.05 mg/ml as compared to uncoated samples. It has been observed that samples also provide a healthy environment for the growth of MG 63 cell lines. It has been noticed that presence of silver nanoparticles on the surface of samples improve degradation and antimicrobial properties.

Silver Doped Nano-Sized Bioglass Ceramics: Synthesis, Characterization and Biocompatibility Studies

We report on the structural and biocompatibility properties of nanosized calcium phosphosilicate bioglass ceramics doped with 0, 2, 4 and 6 mol% Ag2O. Silver doped bioceramics were synthesized by sol-gel method. The prepared samples were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible and high resolution transmission electron microscopy. The XRD reveals the glass-ceramic nature of the samples. The FT-IR spectra show the possible stretching and bending vibrations of silicate and phosphate groups. Absorptions in UV-visible spectra reveal the silver embedment as Ag+/Ago form into the glass matrix. nanosize of the glass ceramics is confirmed by HR-TEM analysis. The bioactivity of silver doped bioceramics was investigated by in-vitro method with Dulbecco’s Modified Eagel’s Medium. It confirms the formation of bone-like hydroxylapatite layer formation on the surface of bioceramics.

Effect of Dopamine on Hydroxyapatite Deposition for Dental Restoration

A novel and biomimetic restoration method for teeth by soaking in a simulated oral environment was reported. A biocompatible polydopamine (PDA) layer was deposited on the surface of dentin via dopamine polymerization to function- alize the surface to induce deposition of hydroxyapatite crystals. The samples were characterized by means of XPS, XRD, SEM and EDS. Results show that the coating of polydopamine layer induces the growth of hydroxyl apatite crystal on dentin surface, and improve the binding force between the hydroxyl apatite layer and the dentin surface. The optimized concentra- tion of dopamine solution is 2 mg/mL for the uniform deposition of PDA layer on the dentin surface.

Evaluation of zinc and magnesium doped 45S5 mesoporous bioactive glass system for the growth of hydroxyl apatite layer

Bioactive glass samples of xZnO(22.4−x)Na2O·46.1SiO2·26.9CaO.2·6P2O5·2MgO system have been prepared by using the sol gel technique. Investigations of structural and bioactive properties of these samples have been undertaken by using X-ray diffraction, field emission scanning electron microscopy, Raman and energy-dispersive X-ray spectroscopy, Brunauer, Emmett and Teller technique, thermogravimetry, differential thermal analysis and derivative thermogravimetry methods and pH studies. X-ray diffraction spectra of prepared samples indicate the formation of hydroxyl apatite layer after 7 and 14days during in vitro analysis. Observed peaks of Raman spectra confirm the growth of hydroxyl apatite layer during in vitro analysis. The formation of apatite phase is responsible for change in the morphology of samples which has been studied by field emission scanning electron microscopy. Ca/P ratio and ion dissolution rate have been evaluated from energy dispersive X-ray spectroscopy results. The observed Ca/P ratio further confirms the growth of apatite layer with time during in vitro analysis. The effect of the addition of zinc on surface area and mesoporous nature of all the samples has been investigated by the Brunauer, Emmett and Teller technique. All glass samples have been found to be thermally stable from thermogravimetry, differential thermal analysis and derivative thermogravimetry techniques. pH studies indicate the non-acidic nature of all the prepared glass samples. Drug release properties of the glass samples have been investigated by using gentamycin as an antibiotic. Prepared samples have shown excellent drug release properties which can be related to the porous nature of the samples. Due to slow dissolution rate, good drug delivery properties and formation of apatite phase within 7 to 14days, our glass samples can be promising candidates for bone regeneration applications.

Development of nano-macroporous soda-lime phosphofluorosilicate bioactive glass and glass-ceramics

We have extended the usefulness of bioactive glass-ceramics for the repair and reconstruction of hard tissues by introducing F ions that are known to be beneficial, especially in dentistry. Nano-macro multimodal porosity in soda-lime phosphofluorosilicate bulk samples was introduced by the recently developed melt-quench-heat-etch method. The choice of starting glass composition is based on 48SiO2-2.7P2O5-xCaF2-yCaO-zNa2O where x = 0, 1, 4, 8, 10, 12, and (y + z) = 49.3-x (mol%). The effect of thermal and chemical treatment on the microstructure of samples is characterized by SEM, XRD and EDX. We find the formation of many crystalline phases, but mainly sodium calcium silicate, calcium phosphate, fluorapatite and calcium silicate. The bioactivity of soda-lime phosphofluorosilicate glass-ceramics is assessed by monitoring the formation of hydroxyl apatite (HA) layer: fluorapatite phase accelerates the rate of HA layer formation; the initial composition and multi-modal porosity are other key parameters that impact the formation of HA. The present porous glass-ceramics should be superior candidates for use in dental bone regeneration.

Investigation of boundary conditions for biomimetic HA deposition on titanium oxide surfaces

To improve the clinical outcome of metal implants, i.e. earlier loading and reduction of the incidence of revision surgery, better bone bonding ability is wanted. One method to achieve this is to change the surface chemistry to give a surface that facilitates bone bonding in vivo, i.e. a bioactive surface. Crystalline titanium oxide has recently been proven to be bioactive in vitro and is an interesting option to the more common hydroxylapatite (HA) coatings on implants. A materials possible in vitro bioactivity is tested through soaking in simulated body fluid and studies of possible HA formation on the surface. For bioactive materials, the formed HA layer can also be used as a coating. The aim of the current paper is to investigate some boundary conditions for HA formation on crystalline titanium oxide surfaces regarding influence from coating thickness, soaking time and soaking temperature. The influence from soaking time and temperature on the HA growth were investigated on oxidised Ti samples, (24 h at 800 degrees C) resulting in a rutile surface structure. The oxidised samples were tested at three temperatures (4, 37 and 65 degrees C) and four times (1 h, 1 day, 1 week and 4 weeks). The influence from titanium coating thickness on the HA growth was investigated via depositing thin films of crystalline titanium dioxide on Ti plates using a reactive magnetron sputtering process. Four different PVD runs with coating thicknesses between 19 and 74 nm were tested. The soaking temperature had an effect on the HA formation and growth on both rutile surfaces and native oxide on Ti substrates. Higher temperatures lead to easier formation of HA. It was even possible, at 65 degrees C, to grow HA on native titanium oxide from soaking in PBS. The coating quality was better for HA formed at 65 degrees C compared to 37 degrees C. All PVD-coatings showed HA growth after 1 week in PBS at 37 degrees C, thus even very thin coatings of crystalline titanium oxide coatings are bioactive.

Bioactive coatings obtained at room temperature with hydroxyapatite and polysiloxanes

Low temperature Hydroxylapatite (HA) coatings were obtained on metal substrates by depositing HA particles suspended in a ormosil polymer gel made of an equimolar mixture of amino and epoxy substituted silanes. The new coatings were analysed by thermal analysis, infrared and solid state NMR, as well as X-ray diffraction and SEM observations. Results show the HA powder conserves its characteristic physicochemical properties during the coating process. Furthermore, the coatings induce the formation of a biomimetic HA layer when soaked in simulated body fluids. This room temperature process may lead to novel calcium phosphate coatings with better control of crystallinity and porosity and with the possible incorporation of biofunctional organic molecules.

SiO2-CaO-K2O coatings on alumina and Ti6Al4V substrates for biomedical applications

Alumina and Ti6Al4V alloys are widely used for orthopedics and dental applications due to their good mechanical properties and biocompatibility. Unfortunately they can not provide a satisfactory osteointegration when implanted. In fact, both alumina and Ti6Al4V are not bioactive and thus they can only guarantee a morphological fixation with the surrounding tissues without a suitable chemical anchorage. Aiming to impart bioactive properties to these materials a coating can be proposed. At this purpose, a bioactive glass belonging to the SiO2-CaO-K2O system was selected and prepared. This glass, named SCK, possess a thermal expansion coefficient matching with the alumina (8.5x 10(- 6)/ degrees C) and Ti6Al4V (9 x 10(- 6)/ degrees C) ones and thus is a good candidate to produce coatings on both of them. Simple and low-cost enameling and glazing techniques were used to realize the coatings. Structural, morphological and compositional characterizations of the coatings were carried out by means of X-ray diffraction, optical and scanning microscopy and compositional analyses. The in vitro properties of the coatings were investigated by soaking them in a simulated body fluid (SBF) in order to study the precipitation, on their surfaces, of a biologically active layer of hydroxylapatite (HAp).

Calcium Phosphate Coatings on the Yalour Islands, Antarctica: Formation and Geomorphic Implications

The formation of calcium phosphate rock coating and its influence in geomorphic processes were investigated on the Yalour Islands (Antarctica). amples of coating on the metamorphosed andesitic rock are composed of a ∼25 μm-thick, white, shiny, relatively hard layer of hydroxylapatite (Hp) with traces of calcite and quartz. Scanning electron micrographs, X-ray diffractograms, Fourier Transform Infrared (FTIR) spectra, and in situ analysis of the chemical composition of the coatings suggest that the calcium phosphate coating is formed mainly through the decomposition of penguin excrement from nearby penguin rookeries and subsequent precipitation of Hp in micropits on the surface of the rock from solutions containing high amounts of calcium and phosphorus. These coatings undergo abiotic and biotic weathering processes that lead to the accumulation of secondary Hp as “flakes” and infillings in microcracks. The coatings give the dark, metamorphosed andesitic rock a shiny, light-colored surface. The coatings can decrease the permeability and increase the albedo of the rock, thereby limiting moisture infiltration (into the rock) and changing the rock’s temperature. Based on theoretical estimates, a change of albedo from 0.2 to 0.3 significantly decreases the radiative heating of the rock during the summer months. These changes to rock properties will influence geomorphic processes such as freeze-thaw, thus affecting rock weathering and hence the evolution of the local landscape.

The effect of biological environment on the surface of titanium and plasma-sprayed layer of hydroxylapatite.

The solubility of titanium samples with different surface coatings, i.e., hydroxylapatite (HA) powders, a two-layer coating of ZrO5+HA on a titanium substrate in solution and of tooth implants after long-term functioning in the human organism, was studied. A minimum difference in solubility of titanium samples with different surface finishes (polished or grit blasted) was established. For the HA powders and coatings, the lowest solubility was observed with a coarse-grained HA-B powder and a coating made of that powder. Clinical tests of tooth implants after long implantation times were performed. A titanium implant (implantation 12 y), a titanium implant with a two-layer coating of ZrO5+HA-A (implantation time 4 y) and a titanium implant with a two-layer coating of (Al5O3+3% TiO2)+HA-A (implantation time 6 y) were studied. The results show that the titanium surface and HA-A layers were dissolved. Nevertheless, after 6 y implantation, total removal of HA-A coating from that part of implant set into the bone, was not observed.

In vitro formation of hydroxylapatite layer in a MgO-containing glass

In the present article, the behaviour of a biologically active glass (BAG) belonging to the system SiO2-CaO-MgO-Na2O-K2O-P2O5, soaked in simulated body fluids (SBFs), is studied. The amount of Ca, Mg and K leached from the glass, as well as variations in P concentration and pH of the solution were measured versus time. The formation of a hydroxylapatite (HA) layer on the glass surface was determined by XRD and SEM-EDX. The article reports the influence of pH variation of the medium on the crystallinity of the HA formed. © 1994 Chapman & Hall.

A procedure for the visualization of bone with hydroxyl-apatite coated implants

A procedure for the histological visualization of the interface between implants coated with hydroxyl-apatite (HA) and bone, and the reaction of bones to the implants, has been developed. Thick sections of bones with HA-coated stainless-steel implants, were investigated with the implant still in situ with routine and (confocal) fluorescence microscopy. The prosthesis-HA-bone interface, bone cells, necrotic and vascularised bone, bone-ingrowth and bone remodelling could be visualised. After removal of the implant from the sections alternative sections were further processed for routine light microscopy, microradiography and detailed fluorescence studies. It appeared that the HA coating was still intact and the integrity of the HA-bone bond was very well preserved. The HA coating layer had the same appearance as after the first inspection with surface microscopy. However, more details were visible. Prosthesis-related and time-related changes in the appearance of the HA layer were detected. The advantage of the procedure is that observations can be made of bone reactions with the prosthesis still in situ, without previous embedding in plastics, and laborous sectioning and/or grinding procedures. Thereafter, sections can be processed for different histological techniques, e.g. immunocytochemistry, routine histology, microradiography, fluorescence microscopy, apparently without imparing the HA coating layer.

Adhesion Properties of Plasma Sprayed Hydroxylapatite Coatings for Orthopaedic Prostheses

Using Air Plasma Spraying (APS) and Vacuum Plasma Spraying (VPS) techniques, hydroxylapatite (HA) and mixtures of HA and titanium (Ti) were deposited on a Ti6A14V alloy (and on an AISI 316L steel) subjected to different surface treatments. The deposits were investigated for their crystallinity, thickness, and adhesion properties. Higher adhesion values were obtained with VPS rather than with APS. By utilising VPS, the deposition conditions were selected in order to achieve crystallinity values between 70 and 90%. The adhesion results depend on the crystallinity (increasing with its decrease), on the thickness (decreasing slightly with its increase) and especially on the surface finish of the metallic substrate. A porous Ti precoat was more effective than either chemical etching in HCl or sandblasting; sandblasting being the least effective. In particular, the double deposits consisting of a porous Ti precoat and a successive layer of HA proved to be most interesting for their higher adhesion properties and for their capability of providing primary stability due to the presence of the HA and secondary stability, in the case of its reabsorption, due to the porous metal.

Plasma sprayed coatings of hydroxylapatite.

The technique of plasma spraying has been applied to deposit a thin, dense layer of hydroxylapatite onto a titanium substrate. Bond strength of such apatite coatings with the substrate have been measured, as well as the (absence of) influence of the coating process on fatigue properties of the substrate. Animal studies showed similar histological reactions to apatite coatings as to (well documented) apatite bulk materials.