Commercial Hydroxyapatite Powder Research Articles

Identification of Proteins Adsorbed on Hydroxyapatite Ceramics with a Preferred Orientation to a-Plane

Protein adsorption is essential for determining material biocompatibility and promoting adherent cell growth. In this study, we focused on the a-plane structure of hydroxyapatite (HAp). This a-plane structure closely resembles the crystal plane where apatite is exposed in long bones. We conducted protein adsorption experiments using HAp ceramics with a preferred orientation to a-planes (aHAp), employing bovine serum albumin (BSA), lysozyme, and fetal bovine serum (FBS) as protein models to mimic the in vivo environment. Higher zeta potential and contact angle values were found in aHAp than in HAp ceramics fabricated from commercial HAp powder (iHAp). Bradford-quantified protein adsorption revealed BSA adsorption of 212 ng·mm−2 in aHAp and 28.4 ng mm−2 in iHAp. Furthermore, the Bradford-quantified protein adsorption values for FBS were 2.07 μg mm−2 in aHAp and 1.28 µg mm−2 in iHAp. Two-dimensional electrophoresis (2D-PAGE) showed a higher number of protein-derived major spots in aHAp (37 spots) than in iHAp (12 spots). Mass spectrometry analysis of the resulting 2D-PAGE gels revealed proteins adsorbed on aHAp, including secreted frizzled-related protein 3 and vitamin K epoxide reductase complex 1, which are involved in cellular bone differentiation. Overall, these proteins are expected to promote bone differentiation, representing a characteristic property of aHAp.

Improving the Mechanical Resistance of Hydroxyapatite/Chitosan Composite Materials Made of Nanofibers with Crystalline Preferential Orientation.

The stability and mechanical properties of hydroxyapatite (HAp)/Chitosan composite materials depend on the dispersion of HAp aggregates in the chitosan matrix and on the chemical interaction between them. Therefore, hexagonal cross-sectioned HAp nanofibers were produced using a microwave-assisted hydrothermal method. Glutamic acid was used to control the HAp crystal growth; thereby, nanofibers were obtained with a preferential crystalline orientation, and they were grown along the “c” axis of HAp crystal structures. This morphology exposed the (300) and (100) crystal planes on the surface, and several phosphate groups and calcium ions were also exposed; they were able to form numerous chemical interactions with the amine, hydroxyl, and carbonyl groups of chitosan. Consequently, the final mechanical resistance of the composite materials was synergistically increased. Nanofibers were mixed with commercial chitosan using a sonotrode to improve their dispersion within the biopolymer matrix and prevent migration. The HAp nanofiber/Chitosan composite materials showed higher mechanical resistance than that observed in similar materials with the same chemical composition that were made of commercial HAp powders, which were used as reference materials. The mechanical resistance under tension of the composite materials made of nanofibers was similar to that reported for cortical bone.

Sintering behavior and mechanical properties of hydroxyapatite ceramics prepared from Nile Tilapia (Oreochromis niloticus) bone and commercial powder for biomedical applications

In this work, Nile tilapia (Oreochromis niloticus) bone was calcined at 800 °C for 5 h in an air atmosphere to obtain hydroxyapatite powder (FB powder). The elemental composition, phase structure, and morphology of the FB powder were investigated and compared with commercial hydroxyapatite powder (SM powder). The FB-powder exhibited 1.01 at. % of Mg while the SM-powder showed Mg in ppm-level. Carbonate groups were detected in the two powders. Both HAp and β-tricalcium phosphate (β-TCP) structures were found in the FB powder, but the SM powder exhibit only the HAp phase. Irregular-shaped particles were observed in the FB powder. After the two HAp powders were sintered at 1200 °C and 1250 °C for 2 h (FB-1200, FB-1250, SM-1200, and SM-1250), the β-TCP intensity peaks of the FB-ceramic samples significantly increased with increasing sintering temperature. The highest relative density, well-packed grains, and β-TCP stabilization by Mg at the Ca5 site of the FB-1250 structure were the dominant factors governing the highest mechanical properties. Although high density was observed in the SM-1200 sample, Vickers hardness of the SM-1200 sample is lower than the FB-1250 sample. This may be attributed to the partial decomposition of HAp into β-TCP, α-tricalcium phosphate (α-TCP), and Ca10(PO4)6O phases. In addition, the increase of grain size was the main factor that governs the increasing compressive strength and Young's modulus instead of density and phase decomposition of the SM-ceramic samples.

Preparation And Characterization Of Natural Nano Hydroxyapatite From Eggshell And Seashell And Its Effect On Bone Healing

The Objectives of the present study were undertaken to prepared hydroxyapatite powder from eggshell and seashell and convert them in Nano size. Hydroxyapatite (HA) is a biomaterial with osteoconductive properties and is prepared by the precipitation method. The properties of HA can be enhanced when the material is synthesized in the Nanoscale range to use in the mandibular bone of the rabbit to examine the influence of (HA) on bone healing.The eggshell and seashell were cleaned, and the phosphoric acid was added. The product inserts in the oven then calcined at 700˚C for 1 hour in the muffled furnace to evaporate CO2 and to get the white crystalline powder, which indicated the presence of HA, this powder was converting to nanoparticle by attraction method. The product was applied in the groove of the rabbit's mandibular bone after surgical procedures to show the bone healing in histological examination. The results of IR Spectroscopy for the eggshell and seashell hydroxyapatite powder showed that the two compounds showed the same IR spectrum and the location of bands is approximately the same in the two compounds compared with the commercial hydroxyapatite powder by using FT-IR spectroscopy after dried at 100˚C. Histologically show that eggshell and seashell hydroxyapatite powder accelerated the bone healing in the mandibular bone of the rabbits. It can be concluded that hydroxyapatite nanoparticles can successfully be produced by chemical precipitation techniques from eggshells and seashells with a phosphoric acid solution. Eggshell and seashell hydroxyapatite powder was used successfully in bone healing

Mechanical testing of hydroxyapatite filaments for tissue scaffolds preparation by fused deposition of ceramics

Composite filaments with diameter ∼1.75 mm suitable for fused deposition of ceramics were prepared from commercial hydroxyapatite powders (HAp-0, d50 ≤ 35 μm and HAp-1, d50 ≤ 16 μm) and thermoplastic polymer - polyvinyl alcohol. The filament printability in FDC applicable as specific bone-part replacements, is connected to its mechanical strength and slenderness ratio affecting the resistance to buckling. The HAp content in prepared composite filaments was at the level of ∼ 50 % and their mechanical properties were compared to commercial filament based on polylactic acid and ∼ 27 % of gypsite used as inorganic filler. The tensile strength of laboratory prepared filaments was about 3 times lower than strength found for commercial filament. The critical buckling pressure calculated from Euler buckling analysis using measured intrinsic Young´s modulus revealed underestimated critical pressure values ∼ 2.5–5.0 times if compared to values of maximal filament compressive pressure loads simulating buckling.

Oxidative decomposition of volatile organic compound on hydroxyapatite with oriented crystal structures

Hydroxyapatite (HAp) exhibits superior biocompatibility, ion-exchange ability and high adsorption property has attracted much attention as one of the most well-known ceramic functional materials. We have previously reported the efficient oxidative decomposition of volatile organic compounds (VOC) on commercial HAp powders, which makes HAp a promising alternative material of precious metal nanoparticle catalyst for environmental purification. In this work, HAp with oriented crystal growth of a-plane and c-plane were synthesized via air-liquid interface precipitation in solution, and the influence of crystal orientation on VOC decomposition performance was systemically investigated. As a result, HAp with preferential growth of c-plane performs higher catalytic VOC decomposition activity, which can be attributed to the large number of active radicals generated on surface despites the relative smaller sufficient surface area. The results in this study highlight the important relation between crystal structure of HAp and the decomposition activity of VOC, which also provide useful information for the structure design of ceramic functional materials.

Laser synthesis of iron nanoparticle for Fe doped hydroxyapatite coatings

Abstract Thin films of iron doped hydroxyapatite have been prepared by nanosecond Pulsed Laser Deposition (PLD). The composite target used for the deposition has been obtained by mixing commercial hydroxyapatite powder with iron-based nanoparticles produced by femtosecond laser ablation in liquid (LAL) (4% of iron nanoparticles). In fact, LAL technique allows to obtain metallic nanostructures without any toxic chemicals and reagents, with a green approach that is crucial for application in biological and medical technologies. Films have been prepared with substrate temperature growing from room temperature (RT) to 500 °C. The effect of deposition temperature on morphology, composition and structural properties of coatings has been investigated. Films deposited at higher temperature result dense and crystalline, they present microscale and nanoscale structures, an average surface roughness of 0.3 μm and magnetic properties suitable for biomedical applications.

Comparative Study of Bioceramic Powders Synthesis Based on Calcium and Phosphates

Abstract In this paper is presented a comparative study regarding the synthesis of hydroxyapatite powders. The chosen method of synthesis of this biomaterial was chemical co-precipitation. The structure, size and morphology of the obtained powders were analyzed by X-ray diffraction, infrared spectroscopy - FTIR, dynamic light diffusion DLS tehnique and scanning electron microscopy-SEM. The results obtained were compared with those obtained on a commercial hydroxyapatite powder. Investigation methods have confirmed the synthesis of a high purity hydroxyapatite with a optimal degree of crystallization and crystallinity for the reconstruction and regeneration of hard tissue.

Physical, mechanical, and biological properties of electrophoretically deposited lithium-doped calcium phosphates

In the present work, the preparation of sintered lithium-doped tricalcium phosphates was studied, along with their physical, mechanical, and biological properties. Calcium phosphates were shaped via the use of electrophoretic deposition (EPD), using colloidally milled dispersions of hydroxyapatite (HAp) particles. The dispersions were stabilised with monochloroacetic acid. Lithium was incorporated into the structure via an addition of lithium chloride, which also served to optimise the deposition process. The dispersions were milled colloidally for periods of 0–48h. The colloidal milling resulted in two effects: i) disintegration of the commercial HAp powder (10µm) agglomerates, ii) unimodal distribution of the HAp particles (~ 170nm). The fine particles of the milled HAp dispersions accelerated the deposition rate, and increased the mass of the deposit. The reduced size of the initial particles, owed to the milling, led to the superior arrangement of the particles during deposition and to reduced porosity after sintering (1050–1250°C). The HAp decomposed into tricalcium phosphate phases during sintering. At a sintering temperature of 1250°C, grain growth occurred, which consequently resulted in a slight degradation of the mechanical properties (reduction in hardness and Young's modulus). In contrast, the hardness and Young's modulus increased as the dispersion milling time increased (smaller grain size after sintering); however, the fracture toughness did not change. The results of the biological testing confirmed the bioactivity of the material through the growth of the apatite layer in the simulated body fluid (SBF), and the biodegradation of the prepared materials in the Tris-HCl solution. With regard to the preparation of compact lithium-doped tricalcium phosphates, the best results were obtained in the case of the sample that utilised the dispersion that was milled for 48h, and was sintered at 1050°C.

Study of the suitability of a commercial hydroxyapatite powder to obtain sintered compacts for medical applications

Hydroxyapatite (HA) is a material widely used by the medical community due to its Ca/P ratio is comparable to the Ca/P ratio of bones and teeth, which promotes osteoinduction and osteoconduction processes when in contact with bone tissue, either as volume piece or coating. This work focuses on studying the quality of the commercial HA powder MKnano-#MKN-HXAP-S12 µm, after processing, to obtain sintered compact discs with suitable physical and chemical characteristics for implants applications. The HA powder was processed through calcination, grinding, pressing and sintering to evaluate the effect of such as procedures in the compacts dics quality. The raw powder was characterized by laser diffraction, SEM, XRF, XRD, TGA and DSC while the characteristics of the obtained compact discs were determined by dilatometry and XRD to identify the sintering temperature range, constituent phases, the amorphous content and the crystallinity degree, parameters that allow determining their suitability for implants applications. Although, it was not possible to obtain sintered compacts with the suitable chemical composition and without fractures, this work allowed to identify the parameters that determine the suitability of a HA powder to obtain sintered compacts for medical applications, as well as the characterization protocol that allows the evaluation of such parameters.

Influence of Starting Powders on Hydroxyapatite Coatings Fabricated by Room Temperature Spraying Method.

Three types of raw materials were used for the fabrication of hydroxyapatite coatings by using the room temperature spraying method and their influence on the microstructure and in vitro characteristics were investigated. Starting hydroxyapatite powders for coatings on titanium substrate were prepared by a heat treatment at 1100 °C for 2 h of bovine bone, bone ash, and commercial hydroxyapatite powders. The phase compositions and Ca/P ratios of the three hydroxyapatite coatings were similar to those of the raw materials without decomposition or formation of a new phase. All hydroxyapatite coatings showed a honeycomb structure, but their surface microstructures revealed different features in regards to surface morphology and roughness, based on the staring materials. All coatings consisted of nano-sized grains and had dense microstructure. Inferred from in vitro experiments in pure water, all coatings have a good dissolution-resistance and biostability in water.

Preliminary Studies of the Effects of Polyethylene Glycol/Hydroxyapatite Powder-Binder System for 3D Printing Application

The role of binder in powder system has gained its importance lately in 3D printing (3DP) applications. This research aims to investigate the effect of powder system developed from incorporation of polyethylene glycol (PEG) onto hydroxyapatite (HAP) powder for 3D printing application. Simple spray method was used to incorporate mixture of PEG into HAP powder. Raw commercial HAP powder was determined by using particle size analyser. The morphology and crystallinity of raw HAP powder and powder mixture were characterised by using Scanning Electron Microscopy (SEM) and X-ray Diffractive (XRD) analysis. Mean particle size of raw HAP was found to be 4.77 μm which is suitable for 3D printing and in good agreement with SEM micrographs. Based on the SEM micrographs, the powder mixture was found in agglomerated and small particle form. Small amount of PEG (2 wt. % to 7 wt. %) incorporation onto HAP powder exhibited absence of new phases on XRD analysis, demonstrating good chemical compatibility. Based on this study, it can be concluded that incorporating PEG onto HAP powder is able to maintain the initial characteristic of HAP and can work together as powder system.

Synthesis and Characterization of Hydroxyapatite Powder from Natural Gypsum Rock

This study prepared hydroxyapatite powder that synthesized from natural gypsum rock and find out physicalchemical and cytotoxicity properties. The synthesis realized by reacting natural gypsum powder with 1M of (NH4)2HPO4 solutions using a microwave. Characterizations of natural gypsum powder and hydroxyapatite powder were conducted by XRD, XRF and SEM. In vitro cytotoxicity testings of hydroxyapatite powder were conducted by MTT method using vero cells. XRD patterns of gypsum powder closed to JCPDF 33-0311 (gypsum standard). Characteristics of gypsum powder i.e. contained 41.72% CaO, level of purity 91,6 % and crystal size 7,147 nm. Charateristic of hydroxyapatite powder that synthesized from natural gypsum powder i.e. contained 46.91% CaO and 40.20% P2O5, XRD patern closed to JCPDF 09-432 (hydroxyapatite standard), level of purity 99 % and crystal size 1.243 nm. There were not significantly difference in cytotoxicity properties of hydroxyapatite powder that synthesized from natural gypsum rock and commercial hydroxyapatite powder (p= 0.086). These results indicated hydroxyapatite powder that synthesized from natural gypsum rock possible to be used as bone substitutes.

Apatite Formation on Titanium Containing Apatite

Some titanium containing apatite (TMA) ceramics prepared by wet synthesis was superior to Hydroxyapatite (HAp) ceramics of mechanical property and cutting performance. In this study, we investigated chemical reaction of TMA in a body environment. Each TMA or commercial Hydroxyapatite powder (HAp) was formed to circular pellets by uniaxial pressing. The specimens were heated in muffle furnace by conventional sintering process. Some TMA specimens were dispensed by alkali and heat treatment. After the treatments, the specimens were soaked in simulated body fluid (SBF: Kokubo’s solution) at pH 7.25 at 37.0°C up to 7 days. Before and after soaking in SBF, the surfaces of the samples were characterized by XRD, SEM, and ICP. After soaking in SBF for 7days, some particles were precipitated on the surface of HAp ceramics and TMA ceramics with alkali and heat treatment. Ti-containing in the crystal structure of HAp affected apatite formation in the body environment.

High‐Performance Hydroxyapatite Scaffolds for Bone Tissue Engineering Applications

Hydroxyapatite (HA) macrochanneled porous scaffolds were produced by polymer sponge templating method using a reactive submicrometer powder synthesized by hydroxide precipitation sol–gel route. The microstructure of the fine HA powder was carefully investigated and developed in order to optimize the mechanical properties and phase stability of sintered scaffold. The templating method ensured a highly interconnected macrochanneled porous structure with over 500 μm mean pore size and 90% porosity. The high reactivity of the powder led to an efficient sintering mechanism with a high and crack‐free linear shrinkage (19 ± 2%) and a significant BET specific surface area reduction (from 12 to 0.33 m2/g). The powder does not dissociate into secondary phases during sintering. Despite the extreme porosity, the scaffolds had high mechanical performance (compressive strength ∼0.51 MPa, Weibull modulus 4.15) compared with literature data and with scaffolds similarly prepared from high‐quality commercial HA powder.

Porous hydroxyapatite ceramics fabricated by an ice-templating method

Porous hydroxyapatite (HA) ceramics with lamellar structures have been fabricated by an ice-templating process using as-synthesized and commercial HA powders. The viscosities of the suspensions prepared using the as-synthesized powders were 9–11 times higher than those of the suspensions prepared using the commercial powders. Finer particle size resulted in larger lamellar pore width and a thinner porous ceramic wall, while a much denser ceramic wall, as well as lower porosity and higher compressive strength, was obtained with the commercial powder.

Elastic Properties of Microwave Sintered Hydroxyapatite

Hydroxyapatite (HA) is widely used as a bone repair material. The use of microwave radiation as energy source for powders densification opens new opportunities for sintering HA at lower temperatures than by conventional sintering (electric furnace). The aim of this work was to compare the densification behaviour of a commercial hydroxyapatite powder under microwave and conventional heating conditions through evaluation of the elastic properties of the resulting sintered materials. The effect of green density, sintering temperature and dwell time on the Young’s modulus E (measured by the impulse excitation of vibration method) of microwave sintered HA was evaluated by using the Taguchi method. Under the set of controlled parameters investigated, green density was the most significant factor affecting E. It was verified that the highest E values obtained with each sintering process are similar (104 and 105 GPa for microwave and conventional sintering, respectively). These values were obtained at 1250°C for 2 h in conventional sintering and at 1200°C for 10 min with microwave sintering. This illustrates the advantage of microwave processing on energy and time savings over conventional sintering.

Aided Sintering Behaviour of Nano Hydroxyapatite Particles

To avoid microcrack formation caused by the addition of heterogeneous sintering aids, nano hydroxyapatite powder was prepared by precipitation method and doped into commercial hydroxyapatite powders as homogeneous sintering aid. Gelcasting method was used to prepare these hydroxyapatite green bodies. Densification of the blended powder was performed by pressureless sintering in air atmosphere at the range 1100°C to 1400°C for 2h, with a step size of 50°C. The results showed that the nano particle can greatly improve the densification process of the green bodies, and at 1300°C, which is the highest sintering temperature for hydroxyapatite without decomposition in the air atmosphere, the relative sintering densities of the doped green bodies and the ones without doping were 93.99% and 83.13% respectively.

Grain-oriented calcium hydroxyapatite ceramic and film prepared by magnetic alignment

Grain-oriented calcium hydroxyapatite (HA) ceramics are potential to enhance or select their bioactive properties. In the current work, highly a-axis oriented calcium HA bulk and thick film samples were prepared by a novel process combining magnetic alignment and polymerization techniques. The slurry containing 40 vol.% commercial HA powder, monomer, initiator and catalyst were poured into a rubber mold for bulk samples or drop-coated on Al 2O 3 substrate for films at first, and then moved them into a vertical 10 T magnetic field. The HA particles in the low viscosity slurry were aligned by magnetic force and then in situ locked via polymerization of the slurry. After sintering, the grain-oriented HA ceramic bulk and thick film samples with a-axis parallel to the magnetic field direction were obtained. Theoretically, the grain-orientation can be easily controlled by adjusting the magnetic field direction.

Different Morphology of Hydroxyapatite Coatings on Titanium by Electrophoretic Deposition

Commercial hydroxyapatite powders were electrophoretically deposited on titanium substrates. In this study, the effect of deposition durations and applied voltages on deposition yield was investigated. Green and sintered coatings were studied by SEM and XRD. It was observed that by applying low voltages and presedimentation, uniform and smooth hydroxyapatite coating can be prepared. In order to obtain roughened hydroxyapatite coatings, high voltages have to be applied. It was concluded that experimental conditions of powder concentration, applied potential, and presedimentation have a significant effect on the deposited coating morphology.