Synthesized Hydroxyapatite Powder Research Articles

Interferometric characterization of high-frequency piezoelectric effects in hydroxyapatite thin films

Hydroxyapatite (HAp) qualities such as biocompatibility and piezoelectricity make it an excellent material for biomedical applications. Here, HAp thin film samples were fabricated onto silica substrates to study their piezoelectric behavior with optical interference. Thin solid films were deposited using previously synthesized HAp powder, sol-gel, and spin-coating techniques. The samples were characterized by scanning electron microscopy, energy dispersive X-ray, Raman, and UV-Vis spectroscopies. The statical piezoelectric effect of the samples was studied by using a finite element method and computational software. Additionally, an experimental Bode analysis allows computing the internal electrical components of the films using high-frequency AC voltage. The electrical behavior is related to the equivalent circuit of a piezoelectric crystal, which indicates the range of frequencies where the electromechanical effect is maximum. A Sagnac interferometer was used to characterize the strain in the HAp as a function of the electrical input frequency. The displacement of the interferometric fringe pattern allows us to estimate the change in the thickness of the sample and compute the piezoelectric constant. The synthesis of HAp thin films with piezoelectric properties provides an effective way to produce sensors and actuators for technological applications.

Densification of Calcium Phosphate from Biogenic Waste for Biomedical Application

Introduction: Calcium phosphate-based biomaterial is commonly employed in biomedical applications such as dental applications, bone substitution and filler tissue engineering. Its excellent biocompatibility and potential bio-implant material have attracted many researchers to broaden their hydroxyapatite (HA) studies. Methods: The present work used waste eggshells as the source of calcium precursor to synthesize HA via a solid-state reaction. The eggshells were calcined at 700°C and mixed with the phosphate precursor, dicalcium phosphate dihydrate (DCPD). Following this, the mixture was ball-milled at 400 rpm for 2h and then heat treated at 800°C to produce pure eggshell-derived HA powder. The synthesized HA powder was then consolidated by uniaxial pressing (~6.5 – 7.1 tons) and sintered at 4 different temperatures of 1100°C, 1150°C, 1200°C and 1250°C. Results: From the XRD analysis of the sintered HA samples, it was found that an increase in sintering temperature up to 1250°C did not affect the phase stability of the HA phase. Besides that, grain size, relative density and hardness of the sintered HA samples were also increased with sintering temperature. It was observed that HA dense sample prepared by compacting at 7.1 tons followed by sintering at 1250°C showed the best combination of mechanical properties among all samples with a relative density of 94.6% and a hardness of 3.7 GPa. Conclusion: The current result is significant in supporting the potential of the synthesized eggshell-derived calcium phosphate powder as an ideal alternative for the creation of cost-effective, biocompatible biomaterials for biomedical applications.

Microwave-Assisted Hydrothermal Treatment of Multifunctional Substituted Hydroxyapatite with Prospective Applications in Bone Regeneration.

Orthopedic bone graft infections are major complications in today's medicine, and the demand for antibacterial treatments is expanding because of the spread of antibiotic resistance. Various compositions of hydroxyapatite (HAp) in which Calcium (Ca2+) ions are substituted with Cerium (Ce3+) and Magnesium (Mg2+) are herein proposed as biomaterials for hard tissue implants. This approach gained popularity in recent years and, in the pursuit of mimicking the natural bone mineral's composition, over 70 elements of the Periodic Table were already reported as substituents into HAp structure. The current study aimed to create materials based on HAp, Hap-Ce, and Hap-Mg using hydrothermal maturation in the microwave field. This route has been considered a novel, promising, and effective way to obtain monodisperse, fine nanoparticles while easily controlling the synthesis parameters. The synthesized HAp powders were characterized morphologically and structurally by XRD diffraction, Dynamic light scattering, zeta potential, FTIR spectrometry, and SEM analysis. Proliferation and morphological analysis on osteoblast cell cultures were used to demonstrate the cytocompatibility of the produced biomaterials. The antimicrobial effect was highlighted in the synthesized samples, especially for hydroxyapatite substituted with cerium. Therefore, the samples of HAp substituted with cerium or magnesium are proposed as biomaterials with enhanced osseointegration, also having the capacity to reduce device-associated infections.

Quantification of phases present in hydrothermally synthesized hydroxyapatite powders from Indian clam seashell by Rietveld refinement method

Quantification of phases present in hydrothermally synthesized hydroxyapatite powders from Indian clam seashell by Rietveld refinement method

The Life Cycle Assessment of the Hydroxyapatite Synthesis from Food Waste Using the Wet Precipitation Method

In Malaysia, food waste had become a significant problem. These recyclable natural waste resources are channeled towards the production of value-added products e.g. hydroxyapatite; which can be used as photo catalyst and many other applications. This study synthesized hydroxyapatite (HAP; Ca10(PO4)6(OH)2) powder from food waste using wet precipitation method. FTIR analysis was done on the synthesized hydroxyapatite powder, calcined samples and raw materials for each resource to study the functional group and the changes of composition in each sample. The Life Cycle Analysis (LCA) study done in this paper comprises of goal and scope definition, life cycle inventory, life cycle impact assessment as well as interpretation of data. Based on the results obtained, FTIR analysis shows that the synthesized powder is indeed hydroxyapatite based on the presence of important feature such as CO32- and PO43- and OH group and egg shell is proven to be the eco-friendliest resource as the production process contributed only 1% to environmental impact.

Characterization and tribological behaviour of Indian clam seashell-derived hydroxyapatite coating applied on titanium alloy by plasma spray technique

Various hydroxyapatite (HA) powders synthesized at different temperatures are deposited on titanium alloy by using an atmospheric plasma spray process. These different HA powders were synthesized from Indian clam seashells through the hydrothermal technique at varying temperatures from 700 to 1000 °C for a 2 h time duration in our previous study. The synthesized HA powders are spray-dried to obtain agglomerated powders suitable for spraying during the coating application. Crystallite size, Ca/P ratio, and crystallinity of agglomerated HA powders and their respective coatings are estimated by standard methods. The microstructure and phases of the feedstock and coating materials are investigated by using a field-emission scanning electron microscope (FESEM) and X-ray diffractometer (XRD), respectively. Further, the HA coatings are characterized in terms of surface roughness, microhardness, porosity, adhesion strength, and wear resistance through the stylus profilometer, Vickers micro-hardness tester, image analysis technique, scratch tester, and ball-on-disc tribometer, respectively. The average surface roughness (Ra) and porosity of the coating are decreased with an increase in the synthesis temperature. The minimum Ra and porosity obtained for the 1000 °C coating sample suggest a high degree of melting of such powder particles. However, the highest adhesion strength noticed in the case of the 900 °C coating sample is due to the high compatibility of such coating material with Ti-alloy substrate in terms of thermal properties. The 900 °C coating sample has also shown the highest microhardness and wear-resistance properties due to its maximum crystallinity among all the HA coatings.

Hydrothermal synthesis of hydroxyapatite powders using Response Surface Methodology (RSM).

Hydroxyapatite (HAp)—[Ca10 (PO4)6(OH) 2] has a similar chemical composition to bone material, making it the main mineral supplement in bone-making. Due to its high biocompatibility, hydroxyapatite is widely used in the repair of bone deficiencies and in the production of dental or orthopedic implants. In this research, hydroxyapatite nanopowder was synthesized using a hydrothermal technique. Fourier Transform Infrared Spectroscopy (FTIR) and transmission electron microscopy (TEM) were used to investigate the chemical structure and morphology of the synthesized hydroxyapatite powder. X-ray diffraction (XRD) was used to evaluate the phase analysis of HAp nanopowder. In addition, bioactivity HAp assessment was conducted by scanning electron microscopy (SEM) attached with Energy Dispersive X-Ray Spectroscopy (EDX) analysis. Response Surface Methodology (RSM) with central composite design (CCD) was used in order to determine the optimal conditions for yield, size, and crystallinity. Three independent variables (pH, temperature, and hydrothermal treatment time) were investigated. The yield was observed to increase in alkaline conditions; pH showed the greatest influence on the yield, size, and crystallinity of the synthesized hydroxyapatite, based on Analysis of Variance. The results of bioactivity evaluation are showed high bioactivity due to the formation of apatite on the surface of the synthesized nanopowder.

Mechanical properties of natural hydroxyapatite using low cold compaction pressure: Effect of sintering temperature

This study describes the effect of sintering temperature on the microstructural, calcium/phosphorus (Ca/P) ion ratios and mechanical properties of non-separated biowastes processed hydroxyapatite (HAp) prepared through a low cold compaction protocol. The HAp was produced by a sintering temperature of 900 °C. Furthermore, HAp sintered at 900 °C was subjected to sintering temperatures of 1000 and 1100 °C.The structural and morphological evolution of the fabricated biomaterials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) respectively. Uniaxial compaction using a pressure of 500 pa was used to produce rectangular shaped pellets to investigate the influence of sintering temperature on the mechanical properties of the produced pellets. From XRD analysis, it was found that hydroxyapatite derived from the biowastes showed good thermal stability and did not exhibit phase instability with traces of other calcium phosphates. The SEM micrographs showed microporous structure of the biomaterials and an increase in temperature reduced the porosity and enhanced the mechanical properties. It was also noticed that the trend of transformation of the average shape of pores was from strongly flattened to round at higher sintering temperatures. Electron dispersive X-ray analysis (EDX) revealed that the atomic Ca/P ratios of the as-sintered HAp specimens ranged from 1.58 to 1.79 for sintering temperatures of 900–1100 °C. The synthesized hydroxyapatite powder showed inclusion of the fluorapatite phase at sintering temperature of 1000 °C with a reduction in the crystallite size. For both scenarios (sintering temperature and compaction pressure), a consistent trend in mechanical properties (microhardness, fracture toughness and Young's modulus) is noticed at every point of measurement except for compressive strength. The reduction in compressive strength when compaction pressure was applied could be as a result of the stress induced in the HAp powders during compaction which may have made it more susceptible to cracks. The hardness value obtained for the synthesized hydroxyapatite pellets is in the range of that of actual human femoral cortical bone.

The influence of electrophoretic deposition of HA on Mg-Zn-Zr alloy on its in-vitro degradation behaviour in the Ringer's solution

Hydroxyapatite (HA) were synthesized via co-precipitation method using Ca(OH)2 and H3PO4 and have been electrophoretically deposited on an as-extruded Mg-6Zn-0.5Zr alloy. The synthesized HA powders were characterized and the over-time (24 h–150 h) degradation behaviour of HA coated Mg alloy has been compared with the bare alloy in the Ringer's solution. Potentiodynamic polarization tests showed that the HA coatings were quite robust till 48 h, started degrading significantly at −1.8 V vs Ag/AgCl after 72 h of immersion and were completely dissolved in 128 h. The 15 μm thick HA coating on ZK60 alloy reduced the anodic current density by one order of magnitude and resulted in more than five times lower uniform corrosion rate. Nyquist plots showed that due to the strong resistance to current flow at low frequency and the strong capacitance of charge double layer at high frequency exhibited by the HA coating, the depressed semicircles of the HA coated sample have larger diameters and heights than the ones for bare alloy. SEM results revealed that the coarse grains had thicker Mg(OH)2 build-up than the fine grains. In addition to the bulk Mg(OH)2, HA coated sample also exhibited nanosized Mg(OH)2 needles believed to be formed via a self-growth process.

Characterization of properties in microwave irradiated-hydroxyapatite

Hydroxyapatite (HA) is a calcium phosphate with a chemical bond of Ca10(PO4)6(OH)2, which is similar to the inorganic substance contained in human bones. Thus makes HA convenient for further development as a biomaterial. The aim of this work is to understand the effect of variation in microwave power and time in synthesizing HA. HA was synthesized by a mixture of calcium hydroxide and di-ammonium hydrogen phosphate, maintaining the molar ratio between calcium and phosphate of 1.67. The sample was irradiated by microwave irradiation at different powers and time duration. The properties of all samples were investigated by x-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDX). The mass of HA samples showed a quite significant change while the crystallite size of the samples reached 34.99 nm. The FTIR results showed some carbonate peaks. It is proved that the change in irradiation power and time affects the properties of the synthesized HA. The synthesized HA powders showed a similar structure to hydroxyapatite in hexagonal P63/m space group a=b=9.418 and c=6.887.

Microstructure-property relations of biphasic calcium phosphate obtained by hot pressing process

Biphasic calcium phosphate (BCP) was fabricated through hot pressing process from hydroxyapatite (HA) starting powder synthesized by a peroxide-based precipitation method and dried at 250?C. The synthesized HA powder contained some calcium hydrogen phosphate (CHP) as a minor phase. In this work, the dense BCP ceramics with a mixture of HA and ?-TCP phases were successfully obtained by hot pressing at temperature ranging from 700-1100?C. The amount of HA phase in the hot pressed samples decreased with increasing sintering temperature from 700 to 900?C, while the amount of ?-TCP exhibited an opposite trend. The relations between the microstructure and mechanical properties of the dense BCP ceramics sintered in the temperature range 700-1100?C were investigated. The sample hot pressed at 800?C has a dense structure with the highest hardness (4.86 ? 0.19GPa) and the lowest fracture toughness (0.80 ? 0.01MPa?m1/2). In addition, biocompatibility of apatite layer formed after immersion in simulated body fluid (SBF) for 14 days can be observed by SEM images. The results revealed that the samples hot-pressed at 800 and 900?C were covered by calcium phosphate (CaP) crystal layer indicating the strong interaction of BCP ceramics and SBF.

Recovering value from waste: biomaterials production from marine shell waste

Marine shell waste is rich in calcium carbonate \((\hbox {CaCO}_{3})\), which can be a good source for the synthesis of hydroxyapatite (HAP). HAP is a potential component in bone tissue engineering as it possesses similar elements to bone structure. In this study, three different species of marine shells that are normally found in Malaysia, namely short-necked clam (Paphia undulate), blood cockle (Anadara granosa) and hard clam (Meretrix lyrata) were used to produce \(\hbox {CaCO}_{3}\) and HAP. The characterization results indicate that the produced \(\hbox {CaCO}_{3}\) consists of mainly aragonite polymorph. Subsequently, the produced \(\hbox {CaCO}_{3}\) was used as the calcium source for the formation of HAP through the wet slurry precipitation method. The results from the analyses on crystallinity, functional group, surface morphology and elemental analysis of the synthesized HAP powders that were obtained through X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) have confirmed that HAP is comparable with other studies. Overall, the results obtained through this study indicate that it is possible to produce \(\hbox {CaCO}_{3}\) and HAP from various marine-based shell waste through greener synthesis routes with less chemicals and reactiontime.

Wet chemical precipitation synthesis of hydroxyapatite (HA) powders

Hydroxyapatite (HA) can be defined as a major member of bioceramic materials world. Production of HA in different forms, especially powder, is still worth to be investigated depending on the development of additive manufacturing systems which get attention in biomedical market, recently. Therefore, in this research, it is aimed to synthesize HA powders following the wet chemical precipitation technique and perform a detailed characterization including chemical, physical, microstructural and mechanical studies. Reaction temperature (30 °C, 50 °C and 85 °C), acid addition rate (slow and rapid acid addition rates) and heat-treatment temperature (950 °C and 1250 °C) were the considered process parameters. After the reaction between the alkaline (calcium hydroxide, Ca(OH)2) and acid (ortho-phosphoric acid, H3PO4) precursors, maturation of the precipitate, decantation of the precipitate and the by-product, drying and eventually heat-treating the precipitate were sequentially done. X-Ray Diffraction (XRD) analyses, Fourier Transform Infrared Spectroscopy (FT-IR) analyses, Differential Thermal-Thermogravimetric Analysis (DTA-TGA), Scanning Electron Microscope/Energy Dispersive Spectroscopy (SEM/EDS) observations, Vickers microhardness and compression strength tests and bulk density, apparent porosity (%) measurements based on the Archimedes’ Principle were carried out to characterize the synthesized HA powders and HA pellets. It is found that a low reaction temperature such as 30 °C and rapid acid addition rate (5.5 ml/min) are proper process parameters to acquire uniform and spherical-like HA powders with ~ 0.2–0.3 µm mean particle size. HA pellets exhibit a high amount of apparent porosity (~ 23–26%) and this situation can be indicated as an important advantage for the transition and penetration of the body fluids towards the pores.

Physicochemical and biological properties of bovine-derived porous hydroxyapatite/collagen composite and its hydroxyapatite powders

An ideal bone repair material should have the features similar to that of natural bones more specifically considering the composition and microstructure. In this investigation, porous hydroxyapatite (HAp)/collagen composite with similar microstructure and composition as that of natural bones was produced from bovine bone. Meanwhile, the pure and natural HAp powders were also prepared from the obtained HAp/collagen composite by two different methods (alkali-heat-treatment and calcination). XRD and FTIR studies of HAp/collagen composite and alkaline-HAp powder confirmed that the HAp phase is carbonate-substituted HAp with a low crystallinity. The samples derived from bovine bone exhibited the major and trace elements of bone, whereas these elements were not found in the chemically synthesized HAp powder. In vitro cell tests indicate that both the HAp/collagen composite and the HAp powders obtained from bovine bone promoted the proliferation and adhesion of MC3T3-E1 cells. These results suggested that the HAp/collagen composite and the HAp powders derived from bovine bone could be used as bone repair materials.

Feedstock Evaluation of Synthesized Hydroxyapatite Powder with Palm Stearin Based Binder System

Feedstock Evaluation of Synthesized Hydroxyapatite Powder with Palm Stearin Based Binder System

Influence of the nano hydroxyapatite powder on thermally sprayed HA coatings onto stainless steel

Abstract The nano Hydroxyapatite (HA) powder was derived from a novel peroxide-based route (PBR) using calcium nitrate, phosphoric acid and hydrogen peroxide as peroxo-precursor. In present work, the effect of nano HA powder on the microstructure and properties of thermally sprayed HA coatings was investigated. The obtained powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD pattern of hydroxyapatite powder corresponded to that of hydroxyapatite and tricalcium phosphate. The nano HA powder was then deposited onto stainless steel substrates using High Velocity Oxy-Fuel (HVOF) method. The influence of the crystallization was evaluated by XRD and SEM. Mechanical property in terms of hardness and bioactivity of the coatings were investigated by Vickers micro hardness testing and soaking in simulated body fluid (SBF), respectively. The results showed that the HA coatings were a mixture of amorphous and crystalline phase. The hardness value of 2.15 ± 0.08 GPa was obtained for the synthesized HA powder coating (SHAC). After soaking in SBF for 14 days, the layer formation of apatite could be observed.

Self-Setting Calcium Phosphate Cements with Tunable Antibiotic Release Rates for Advanced Antimicrobial Applications.

Osteomyelitis, an infectious disease predominantly tied to poor sanitary conditions in underdeveloped regions of the world, is in need of inexpensive, easily in situ synthesizable and administrable materials for its treatment. The results of this study stem from the attempt to create one such affordable and minimally invasive therapeutic platform in the form of a self-setting, injectable cement with a tunable drug release profile, composed of only nanoparticulate hydroxyapatite, the synthetic version of the bone mineral. Cements comprised two separately synthesized hydroxyapatite powders, one of which, HAP2, was precipitated abruptly, retaining the amorphous nature longer, and the other one of which, HAP1, was precipitated at a slower rate, more rapidly transitioning to the crystalline structure. Cements were made with four different weight ratios of the two hydroxyapatite components: 100/0, 85/15, 50/50, and 0/100 with respect to HAP1 and HAP2. Both the setting and the release rates measured on two different antibiotics, vancomycin and ciprofloxacin, were controlled using the weight ratio of the two hydroxyapatite components. Various inorganic powder properties were formerly used to control drug release, but here we demonstrate for the first time that the kinetics of the mechanism of formation of a solid compound can be controlled to produce tunable drug release profiles. Specifically, it was found that the longer the precursor calcium phosphate component of the cement retains the amorphous nature of the primary precipitate, the more active it was in terms of speeding up the diffusional release of the adsorbed drug. The setting rate was, in contrast, inversely proportional to the release rate and to the content of this active hydroxyapatite component, HAP2. The empirical release profiles were fitted to a set of equations that could be used to tune the release rate to the therapeutic occasion. All of the cements loaded with vancomycin or ciprofloxacin inhibited the growth of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli and Pseudomonas aeruginosa in both agar diffusion assays and broth dilution tests with intensities either comparable to the antibiotic per se, as in the case of ciprofloxacin, or even larger than the antibiotic alone, as in the case of vancomycin. Interestingly, even the pure cements exhibited an antibacterial effect ranging from moderate to strong, while demonstrating high levels of biocompatibility with osteoclastic RAW264.7 cells and only slightly affecting the viability of the osteoblastic MC3T3-E1 cells, in direct proportion with the amount of the more active hydroxyapatite component in the cements. This antibacterial effect was especially noticeable against Gram-negative bacteria, where the growth inhibition by the cements was comparable to or even stronger than that of the pure antibiotics. The antibiofilm assay against P. aeruginosa biofilms reiterated the antibiotic effectiveness of pure, antibiotic-free cements. That the carrier per se, composed of a nontoxic, easily prepared, bone mineral composite, can exhibit a strong antibacterial effect even in the absence of an antibiotic drug is an insight highly relevant in view of the rising resistance of an array of pathogens to traditional antibiotic therapies and the demands for the timely development of suitable alternatives.

Synthesis and Characterization of Hydroxyapatite Powder by Eggshell

Hydroxyapatite (HA) having chemical formula Ca10(PO4)6(OH)2, is the main chemical component of human bone tissue (70%). This is the reason why it has been widely engaged in the dental and non-load bearing implantations, to cope up with the bone response as a bioactive material. In this study HA powder was synthesized by wet chemical method, using phosphoric acid (H3PO4) and eggshells. The synthesized HA powder was characterized by X-ray diffraction analysis, Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier transform (FT-IR) spectroscopy. The Thermos gravimetric analysis (TGA-DTA) was also carried out to evaluate the stability of the synthesized HA powder at higher temperatures. The results of the study indicate that sintered (at 900°C) HA powder resembles the feature of pure and single apatite phase having favourable Ca/P ratio ranging from 1.7 to 2.4.

Magnesium Doped Hydroxyapatite through Mechanochemical Synthesis

The mechanochemical synthesis method was employed to synthesis hydroxyapatite (HA) and magnesium (Mg) doped hydroxyapatite (HA) powders. The effects of Mg2+ into the synthesized HA powder properties were investigated. Characterization of the synthesized HA (Mg-free HA) and Mg–doped HA at various concentrations (1% - 9% MgHA) were accomplished through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses. The nano size powder of HA and Mg-doped HA were successfully synthesized through the present method and the influenced of Mg2+ in the HA was also indicated by the different peaks intensity and the crystal sizes obtained.

The Effects of Calcium‐to‐Phosphorus Ratio on the Densification and Mechanical Properties of Hydroxyapatite Ceramic

In this work, hydroxyapatite (HA) powders were synthesized using calcium hydroxide Ca(OH)2 and orthophosphoric acid H3PO4 via wet chemical precipitation method in aqueous medium. Calcium‐to‐phosphorus (Ca/P) ratio was set to 1.57, 1.67, 1.87 that yield calcium‐deficient HA, stoichiometric HA, and calcium‐rich HA, respectively. These synthesized HA powders (having different Ca/P ratio) were characterized in terms of particle size and microstructural examination. Then, the densification and mechanical properties of the calcium‐deficient HA, stoichiometric HA, and calcium‐rich HA were evaluated from 1000 to 1350°C. Experimental results have shown that no decomposition of hydroxyapatite phase was observed for stoichiometric HA (Ca/P = 1.67) and calcium‐deficient HA (Ca/P = 1.57) despite sintered at high temperature of 1300°C. However, calcium oxide (CaO) was detected for calcium‐rich HA (Ca/P = 1.87) when samples sintered at the same temperature. The study revealed that the highest mechanical properties were found in stoichiometric HA samples sintered at 1100–1150°C, having relative density of ~99.8%, Young's modulus of ~120 GPa, Vickers hardness of ~7.23 GPa, and fracture toughness of ~1.22 MPam1/2.