Amount Of Hydroxyapatite Research Articles

Synthesis and Characterization of Hydroxyapatite from Green Mussel Shell with Sol-Gel Method

Hydroxyapatite (HAp) is a major component of bones and teeth. HAp is widely used to repair, fill, extend, and reconstruct damaged bone tissue. HAp is used for bone and dental implants, so it is necessary to synthesize HAp. HAp synthesis can utilize green mussel shell waste as a calcium precursor. This research synthesized HAp from a green mussel shell using the sol-gel method. The controlled synthesis parameter was pH, and the variable being compared was the heating temperature at 900 and 1100 °C. The HAp products were characterized by an X-ray diffractometer (XRD), Fourier-transform infrared spectrophotometer, and scanning electron microscope. The results showed that HAp was formed at alkaline pH, namely at pH 11. The XRD pattern showed that Hap was formed along with type A apatite carbonate, octacalcium phosphate, α- and β-tricalcium phosphate. The crystallinity was increased by raising the temperature and prolonging the heating time. The quality of HAp will improve with increasing crystallinity, and increasing the temperature will also raise the amount of HAp formed.

Investigation of mechanical properties of UHMWPE composites reinforced with HAP+TiO2 fabricated by solvent dispersing technique

This work seeks to contribute to solving the problems of inadequate artificial joint design from the mechanical perspective in total joint replacement (TJR) surgery. Ultra-high molecular weight polyethylene (UHMWPE)/hydroxyapatite (HAP) + titanium dioxide (TiO2) hybrid composites were fabricated and tested for use as artificial cartilages in the total joint prosthesis. Different amounts of TiO2 (1–10 wt%) and fixed amount of HAP (20 wt%) were dispersed in UHMWPE-based nanocomposites due to obtaining a material easy to be processed, inexpensive, with remarkable mechanical properties, and good cells interaction. The UHMWPE/HAP + TiO2 composites were prepared by using the solvent dispersing technique and twin-screw mixer, followed by hot compression molding, then mechanical testing was performed. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) are used to study the effect of the additives and the dispersion quality of the composites. The solvent dispersing technique shows better dispersion of the additives in the polymer matrix. The composites show an increase in Young's modulus, hardness, and flexural strength, by 71%, 33%, and 95% respectively concerning neat UHMWPE. The composite contains 3 wt% TiO2 showing the best enhancement percentage.

Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic.

The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45–100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 °C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells’ number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure.

Optimization of hydroxyapatite powder mixed electric discharge machining process to improve modified surface features of 316L stainless steel

Traditional methods for producing 316L steel with a desired roughness and a uniform thin coating for sufficient bioactivity and long-term durability are highly difficult and require post-processing. Electric discharge machining (EDM) is a nontraditional process that can accomplish both machining and coating the surface concurrently. This study provides a thorough examination of the impacts of EDM process parameters on the machining responses, which are significantly necessary for processing 316L steel to reach its full potential. The nano-hydroxyapatite particles added EDM method is used to improve the machining and the surface responses. EDM process parametric optimization is conducted using Taguchi's design to achieve the lowest surface roughness of 2.04 µm and a recast layer thickness of 6.11 µm. As a machinability metric, the greatest material erosion rate (MER) of 20.64 mg/min is achieved. Current intensity, discharge period and hydroxyapatite amount are identified to be important predictors for MER, surface roughness and recast layer thickness. Scanning electron microscope with the energy dispersive X-ray spectrums and atomic force microscopic images validate the machined surface morphology, elemental compositions and surface topography. Errors of the confirmatory tests are less than 10%, showing that the projected solution sets by the grey wolf optimizer are highly accurate. The study shows a thin recast layer with both nano and micro-surface roughness formation, which have a great importance in biomedical applications.

Effects of Diatomite Contents on Microstructure, Microhardness, Bioactivity and Biocompatibility of Gradient Bioceramic Coating Prepared by Laser Cladding

Biometallic materials are widely used in medicine because of excellent mechanical properties. However, biometallic materials are limited in the application of biomaterials due to their lack of bioactivity. To solve this problem, a gradient bioceramic coating doped with diatomite (DE) was successfully fabricated on the surface of Ti6Al4V alloy by using the broadband-laser cladding process to improve the bioactivity of metal materials. As well as the DE contents on the microstructure, microhardness, bioactivity and biocompatibility were investigated. The experimental results demonstrate that the addition of moderate amounts of DE is effective in reducing the number of cracks. The X-ray diffraction (XRD) results reveal that the bioceramic coating doped with DE mainly consists of CaTiO3, hydroxyapatite (HA), tricalcium phosphate (TCP) and silicate, and that the amount of HA and TCP in the coating reached maximum when the bioceramic coating was doped with 10wt% DE. The bioceramic coating doped with 10wt% DE has favorable ability to deposit bone-like apatite. These results indicate that the addition of DE can improve cracking sensibility, bioactivity and biocompatibility of the coating.

Simultaneous Precipitation and Electrodeposition of Hydroxyapatite Coatings at Different Temperatures on Various Metal Substrates

The coating of orthopedic and dental implants with hydroxyapatite (HA) is recognized as a method to increase their integration ability. A new metal coating method, comprising simultaneous precipitation and electrodeposition, is presented. Two studies are described: the first is related to the influence of time/temperature increase on the morpho-structural characteristics of the deposited layer on the Ti substrate, while the second study presents the characteristics of the layers deposited on different metal substrates. For comparison, specimens were obtained using the classical electrochemical deposition under the same experimental conditions. The addition of Ca to the electrolyte creates more compact and more uniform coatings, while the addition of P creates more porous layers. Only a very small quantity of crystalline HA deposited on the C55, Cu, and Ni substrates when the classic electrodeposition method was employed, while using the new approach has clearly led to a larger crystalline HA amount electrodeposited on the same types of metals. With some exceptions, the advantages of using the new method are: better crystallinity, more uniform and continuous surface, higher roughness, and potentially higher anti-corrosion capabilities.

Fabrication and Characterization of PCL/HA Filament as a 3D Printing Material Using Thermal Extrusion Technology for Bone Tissue Engineering.

The most common three-dimensional (3D) printing method is material extrusion, where a pre-made filament is deposited layer-by-layer. In recent years, low-cost polycaprolactone (PCL) material has increasingly been used in 3D printing, exhibiting a sufficiently high quality for consideration in cranio-maxillofacial reconstructions. To increase osteoconductivity, prefabricated filaments for bone repair based on PCL can be supplemented with hydroxyapatite (HA). However, few reports on PCL/HA composite filaments for material extrusion applications have been documented. In this study, solvent-free fabrication for PCL/HA composite filaments (HA 0%, 5%, 10%, 15%, 20%, and 25% weight/weight PCL) was addressed, and parameters for scaffold fabrication in a desktop 3D printer were confirmed. Filaments and scaffold fabrication temperatures rose with increased HA content. The pore size and porosity of the six groups’ scaffolds were similar to each other, and all had highly interconnected structures. Six groups’ scaffolds were evaluated by measuring the compressive strength, elastic modulus, water contact angle, and morphology. A higher amount of HA increased surface roughness and hydrophilicity compared to PCL scaffolds. The increase in HA content improved the compressive strength and elastic modulus. The obtained data provide the basis for the biological evaluation and future clinical applications of PCL/HA material.

Improvement in bioactivity and corrosion resistance of Ti by hydroxyapatite deposition using ultrasonic mechanical coating and armoring

In the present work, nanostructured hydroxyapatite (HA)-containing coating was prepared on a Ti surface by ultrasonic mechanical coating and armoring (UMCA). A Ti plate was pre-coated with HA slurry, followed by UMCA, which was achieved by high-frequency ZrO 2 ball bombardment. The UMCA process comprised several cycles of pre-coating and ball bombardment, providing high amounts of HA and good coating adhesion. The coating mainly consisted of nano-HA particles (less than 10 nm) and a small amount of Ti. Furthermore, the deformation structures of the Ti surface region were characterized in a nanocrystalline layer with a grain size of 50–200 nm. Additionally, the coating exhibited improved bioactivity and corrosion resistance in Hanks’ balanced salt solution than the Ti surface. Furthermore, the in vitro cytotoxicity test assessed that the HA-containing coating was non-cytotoxic.

Performance and Mechanisms of PropS-SH/HA Coatings in the Inhibition of Pyrite Oxidation

Acid mine drainage (AMD) entering the environment will cause long-term environmental pollution and ecological damage, the treatment or remediation for which has become a difficult worldwide problem. To control AMD at the source, a novel composite coating, hydroxyapatite (HA) as the filler embedded in a γ-mercaptopropyltrimethoxysilane (PropS-SH) coating, was introduced in this study. The performance and mechanisms of PropS-SH/HA coatings in the inhibition of pyrite oxidation were investigated by chemical leaching testing and material structure characterization. The results of the investigations revealed that the addition of an appropriate amount of HA can enhance the passivation efficiency of the PropS-SH coating. The best coating was obtained from 3% (v/v) of PropS-SH solution with 16 wt % HA, as this coating decreased pyrite oxidation by 78.7% (based on total Fe release). The main mechanism of PropS-SH/HA for the inhibition of pyrite oxidation involved the generation of a PropS-SH network through a polycondensation reaction. The addition of HA increased the stability of the passivation film composed of PropS-SH as well as the combining capacity of PropS-SH/HA through the formation of Si–O–Si and Fe–O–Si bonds, respectively.

3D porous PCL-PEG-PCL / strontium, magnesium and boron multi-doped hydroxyapatite composite scaffolds for bone tissue engineering

Bioceramic/polymer composite systems have gained importance in treating hard tissue damages using bone tissue engineering (BTE). In this context, it was aimed to develop 3D porous composite PCL-PEG-PCL scaffolds containing different amounts of B, Sr and Mg multi-doped HA that can provide bone regeneration in the bone defect area and to investigate the effect of both the amount of inorganic phase and the porosity on the mechanical and the biological properties. B–Sr–Mg multi-doped HA and PCL-PEG-PCL copolymer were successfully synthesized. PCL-PEG-PCL composite scaffolds containing different amounts of hydroxyapatite (HA) (10% and 20 wt%) were produced with the desired porosity (50% and 60%) by compression-molding and particulate leaching method. The porosity of the scaffolds was determined between 47% and 59%. HA/PCL-PEG-PCL composite scaffolds were subjected to a 3-week degradation test and showed negligible (0.2–0.5%) degradation. The water uptake percentage of the composite scaffolds with 60% porosity was the highest among all groups. Presence of HA in the scaffolds improved the water adsorption and the mechanical properties. Compressive strength of the scaffolds was between 9.32 and 24.27 MPa and 20% 2Sr0.5BHA scaffolds were found to have the maximum compressive strength. Compressive strength of 50% porous samples was higher than that of 60% porous samples. In the relative cell viability (%) test, the highest viability was observed on the scaffolds with HA and 2Sr0.5BHA. The specific ALP activity level of the cells on the scaffolds containing 2Sr0.5BHA was significantly higher (2.6 times) than that of the control group. The amount of porosity did not make a significant difference in cellular response. It was concluded that PCL-PEG-PCL composite scaffolds with 2Sr0.5BHA have the potential to be used in BTE.

In Situ Biomineralized Phosphorylated Poly(l-Glutamic Acid)/Sodium Alginate Injectable Hydrogels

Biomineralized hydrogels have attracted much attention as biomaterials for bone regeneration. In our research described here poly(L-glutamic acid) (PLGA) was activated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysulfosuccinimide to prepare PLGA-NHS active ester, which was then reacted with adipic acid hydrazide (ADH) and phosphorylethanolamine (PA) to obtain phosphonic and hydrazide-modified poly(L-glutamic acid) (PLGA-ADH-PA). The Schiff base reaction between PLGA-ADH-PA and oxidized alginate (OALG) led to the formation of phosphorylated PLGA/ALG injectable hydrogels. The nano-hydroxyapatite (nHA)/PLGA/ALG composite hydrogels were obtained by in situ biomineralization of the phosphorylated PLGA/ALG hydrogels in simulated body fluid. The chemical structure and rheological properties of the hydrogels before and after mineralization, and the size and morphology of the nHA were studied. After biomineralization, the growth of HA with soaking time was detected at the surface and interior of the PLGA/ALG hydrogels. The average sizes of the nHA particles were 120 nm and 350 nm, respectively, at 12 h and 5 d. The amount of hydroxyapatite deposited increased with the increase of PA grafting degree. Compared with unmineralized hydrogels, the mechanical properties of the mineralized hydrogels were significantly improved.

Physico-chemical properties and biocompatibility of in situ-hardening polylactide/nano hydroxyapatite composite for bone substitute

Polylactide (PLA) and hydroxyapatite (HA) composite is a promising material for biomedical applications. The bioresorbability and adequate strength of PLA in combination with the bioactivity of HA clearly provide prospective properties for resorbable bone substitute. The material, however, requires to be shaped prior to surgery, which impedes its practical use, particularly in complex shaped bone defects. In this study, a novel combination of star-shaped and linear PLA powder with various amounts of nano HA, and triethylene glycol dimethacrylate liquid was developed as an in situ forming cement for bone substitute. The effects of different amounts of initiator (0.5 and 1 wt%) and nano HA powder (5, 10, and 15 wt%) on various properties of the composite cement, including handling properties, degree of conversion, gel fraction, residual monomer toxicity and osteoblast differentiation were studied. The in vitro degradation was also examined in terms of weight and mechanical loss. The results demonstrated that the amount of initiator had a great effect on the handling properties of the cement, however, the HA content did not have any significant effect. The increasing HA content slowed down the degradation rate of the cement. All cement formulations in this study exhibited good network forming and ability to induce osteoblast differentiation with negligible residual monomer release to harm cells. The optimal cement formulation was found to be at 15 wt% HA, which allowed for in situ hardening with satisfactory biocompatibility and mechanical support for bone regeneration during deterioration.

New Sintered Porous Scaffolds of Mg,Sr Co-Substituted Hydroxyapatite Support Growth and Differentiation of Primary Human Osteoblasts In Vitro

Strontium (Sr) and Magnesium (Mg) are bioactive ions that have been proven to exert a beneficial effect on bone; therefore, their incorporation into bone substitutes has long been viewed as a possible approach to improve tissue integration. However, the thermal instability of Mg-substituted hydroxyapatites has hitherto limited development. We previously described the creation of thermally consolidated porous constructs of Mg,Sr co-substituted apatites with adequate mechanical properties for their clinical use. The present paper describes the biocompatibility of Mg,Sr co-substituted granules using an alveolar-bone-derived primary model of human osteoblasts. Cells were cultured in the presence of different amounts of hydroxyapatite (HA), Sr-substituted HA, or MgSrHA porous macrogranules (with a size of 400–600 microns, obtained by grinding and sieving the sintered scaffolds) for three and seven days, and their viability was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Protein content was measured using the Lowry assay at the same time points. Cell viability was not impaired by any of the tested compounds. Indirect and direct biocompatibility of these macrogranules was assessed by culturing cells in a previously conditioned medium with HA, SrHA, or MgSrHA, or in the presence of material granules. Osteoblasts formed larger and more numerous nodules around SrHA or MgSrHA granules. Furthermore, cell differentiation was evaluated by alkaline phosphatase staining of primary cells cultured in the presence of HA, SrHA, or MgSrHA granules, confirming the increased osteoconductivity of the doped materials.

Impact of High-Dose Anti-Infective Agents on the Osteogenic Response of Mesenchymal Stem Cells.

Treatment of infected nonunions and severe bone infections is a huge challenge in modern orthopedics. Their treatment routinely includes the use of anti-infective agents. Although frequently used, little is known about their impact on the osteogenesis of mesenchymal stem cells. In a high- and low-dose set-up, this study evaluates the effects of the antibiotics Gentamicin and Vancomycin as well as the antifungal agent Voriconazole on the ability of mesenchymal stem cells to differentiate into osteoblast-like cells and synthesize hydroxyapatite in a monolayer cell culture. The osteogenic activity was assessed by measuring calcium and phosphate concentrations as well as alkaline phosphatase activity and osteocalcin concentration in the cell culture medium supernatant. The amount of hydroxyapatite was measured directly by radioactive 99mTechnetium-HDP labeling. Regarding the osteogenic markers, it could be concluded that the osteogenesis was successful within the groups treated with osteogenic cell culture media. The results revealed that all anti-infective agents have a cytotoxic effect on mesenchymal stem cells, especially in higher concentrations, whereas the measured absolute amount of hydroxyapatite was independent of the anti-infective agent used. Normed to the number of cells it can therefore be concluded that the above-mentioned anti-infective agents actually have a positive effect on osteogenesis while high-dose Gentamycin, in particular, is apparently capable of boosting the deposition of minerals.

Effect of hydroxyapatite content and particle size on the mechanical behaviors and osteogenesis in vitro of polyetheretherketone–hydroxyapatite composite

AbstractPoly‐ether‐ether‐ketone (PEEK) possesses excellent biocompatibility and similar elastic modulus as bones but suffers from poor osseointegration; usually, the addition of hydroxyapatite (HA) is considered as an effective way to improve the osseointegration of PEEK implant interface. To investigate the effect of HA content and particle size on the mechanical behaviors and osteogenesis in vitro of PEEK‐HA composites, the PEEK‐HA specimens with variable HA content and particle size have been fabricated by powder mixing‐heat press method and characterized by mechanical and biological tests. The results showed that the tensile/bending strength and elongation at break of PEEK‐HA are significantly impaired as the increasing HA amount, but the modulus improves. The compressive strength and modulus are improved as the increasing amount of HA. The PEEK‐HA with smaller HA particle size possesses higher‐performance tensile/bending and lower‐performance compressive properties. In osteogenesis tests in vitro, the results reveal that the cells amount attached on the substrate rises and the cells flatten more evenly with numerous cytoplasmic processes on greater area with the increasing HA content and decreasing particle size. The PEEK‐HA group that HA content is 20 wt% and particle size is 20 nm exhibits optimal‐performance osteogenesis in vitro, while maintaining sufficient mechanical properties.

Hydroxyapatite-embedded levan composite hydrogel as an injectable dermal filler for considerable enhancement of biological efficacy

We previously developed an injectable levan-based hydrogel as a temporary dermal filler. However, the longevity and collagen stimulation effect of the levan-based hydrogel were limited. Herein, we prepared hydroxyapatite (HAp)-embedded levan composite hydrogel as a long-acting dermal filler for enhancing in vivo collagen production and anti-wrinkle efficacy. HAp amount (0.1–5 wt%) in the levan hydrogel was optimized for stability, safety, and efficacy. Increasing the HAp amount decreased the in vitro stability and elastic modulus, but the composite hydrogel structure was still maintained. Furthermore, the composite hydrogel showed improved cell proliferation stimulation compared to the bare levan hydrogel in human dermal fibroblast cells. In vivo stability of the composite hydrogel was enhanced in contrast to the in vitro result, showing stable residence of the composite hydrogels with 0.5 or 1 wt% HAp over 8 weeks. Moreover, the excellent anti-wrinkle efficacy of composite hydrogel with 1 wt% HAp was maintained during 8 weeks and it showed the highest collagen production. Thus, HAp-embedded levan composite hydrogel showed potential as a dermal filler with easy injectability, biocompatibility, and long-acting anti-wrinkle efficacy.

Selective Laser Melting of Ti6Al4V-2%Hydroxyapatite Composites: Manufacturing Behavior and Microstructure Evolution

In this work, selective laser melting of Ti6Al4V (Ti64) and 2 wt.% hydroxyapatite (HA) composites was performed with the purpose of osseointegration enhancement and biological fixation between implants and bone tissue. The microstructural evolution and mechanical properties were analyzed by using X-ray diffraction (XRD), optical microscopy (OM), a scanning electron microscope (SEM) equipped with (EDX) and (EBSD) systems, microhardness, nanoindentation, and tensile testing. The results showed that the Ti64-2%HA composite components exhibited complicated manufacturing behavior, which could be correlated with the decomposition of HA. The microstructure was found to mainly consist of α Ti with a small amount of HA distributed along grain boundaries. Furthermore, the interaction between Ti64 and HA leading to the formation of Ti3P, TixO, P, and CaTiO3 phases, resulted in poor tensile properties, as compared to pure Ti64 components. Conversely, the tensile properties of SLM Ti64-2%HA composite components were significantly higher than human bone reported previously in the literature.

Experimental measurement and simulation of mechanical strength and biological behavior of porous bony scaffold coated with alginate-hydroxyapatite for femoral applications

In the present study, the 3D printer method for fabricating porous bone scaffolds with Polylactic Acid (PLA) printed was used by Fused Deposition Modelling (FDM). Then, the prepared 3D scaffold coated with alginate composed with various amounts of Hydroxyapatite (HA) using the freeze-drying technique. After the fabrication of novel functional graded materials scaffold, the mechanical strength and biological behavior were investigated. The Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis used to characterize the morphology and phase characterization. The structure of the porous scaffold was simulated using the ABAQUS analysis method and their mechanical and physical properties were extracted. Also, strong antibacterial properties were observed for all samples with increasing HA nanoparticles against gram-positive and gram-negative bacterial suspensions. These bio-nano composites are compatible with the pH of the blood. In general, it was found that the most suitable bio-nano composite is the sample with 10 wt % HA nanoparticles. The elastic modulus increased from 350 MPa to 394 MPa with the addition of HA nanoparticles, while the porosity percentages decreased from 44 % to 36 %. The compressive strength increases from 25.2 MPa to 32.7 MPa with the addition of 30 wt% HA nanoparticles. The obtained results showed that the bio-nano composites prepared in this study were suitable for further development in bone substitutes with desirable mechanical properties. The alginate/HA material properties reported from the numerical approach, have an acceptable agreement with experimental results. Furthermore, the numerical study indicated that the scaffold compressive strength increases from 22.8 MPa (S1) to 31.2 MPa (S4) with the addition of 30 wt % HA nanoparticles. Nanoindentation test explains that the indenter penetration decreases from 82.163 nm to 69.338 nm with the addition of 30 wt% HA nanoparticles. As a consequence, PLA-alginate/20 wt % HA (S3) and, PLA-alginate/30 wt% HA (S4) have the best mechanical properties. Although due to lower biological advantages of S4 concerning S3, PLA-alginate/20 wt % HA (S3) chose as an appropriate bio-nanocomposite for orthopedic application.

Effect of hydroxyapatite nano rods on sinterability, hardness and bioactivity of Fe-14Mn-6Si alloy prepared by powder metallurgy

Recently, there is a great of industrial interest on the production of biodegradable metal/ceramic composites. The casted Fe-Mn-Si alloys prepared by casting tools have low biodegradable rate; so it is important to seek a method as powder metallurgy (PM) to prepare porous bodies with increased biodegradability. Moreover, the addition of hydroxyapatite (HA) nano rods to that alloy increases its bioactivity and forms composite with improved properties. In the present study, Fe-14Mn-6Si/HA composites were prepared by PM and sintered at different temperatures, i.e. 1100, 1150 and 1200oC. Also, the effect of HA nano-rods content on the composite properties (physical properties, microstructure and micro hardness) and bioactivity were studied. The results revealed that bulk density increased with increasing sintering temperature up to 1150oC; then decreased at 1200oC. Also, the bulk density increased with increasing the HA content. Moreover, the hardness of the sintered composites increased with increasing sintering temperature and HA amount. The maximum hardness values were 1293 & 1792 MPa for the specimens which contain 8 % HA and sintered at 1150 and 1200oC, respectively. The bioactivity of the prepared composites increased with increasing HA amount. The highest bioactivity was for the composite that contains 8 wt.% HA.

Effect of heat treatment on the synthesis of hydroxyapatite from Indian clam seashell by hydrothermal method

Hydroxyapatite (HA) powder has been successfully synthesized from low-cost Indian clam seashells by using hydrothermal method. The mixture of tri-calcium phosphate [Ca3(PO4)2], heat-treated ball-milled clam seashell, and demineralized water are heat-treated at several temperatures (700 °C, 800 °C, 900 °C, 1000 °C, and 1100 °C) for various time periods (1 h, 2 h, and 3 h) to perform the hydrothermal reactions. The phases and microstructure of the solid-state reaction products are analyzed through X-ray diffraction (XRD) method and field emission scanning electron microscopy (FESEM) respectively. The crystallite size of all the synthesized powders is calculated by using Scherrer's model. Mainly HA phase is obtained in all the different reaction products. However, these HAs are found to be non-stoichiometric in nature. As per the literature, non-stoichiometric HA is a more biologically active material compared to the stoichiometric one. Almost pure HA is formed with any selected reaction temperature applied for 2 h time duration. The crystallinity and Ca/P ratio of the synthesized pure HA are estimated by using standard model and energy-dispersive X-ray spectroscopy (EDS) analysis, respectively. The highest amount of near stoichiometric crystalline HA has been obtained at 900 °C of reaction temperature applied for 2 h time duration. With raising reaction temperature, the grain size of pure HA is found to be increased. Needle/rod shaped nano grains are noticed to form at lower reaction temperature whereas; beyond 1000 oC of temperature globular/spherical shaped grains are also observed to form. At 3 h reaction time agglomeration of grains is found to occur in all the synthesized powders.