Fabrication Of Hydroxyapatite Research Articles

Fabrication and characterization of hydroxyapatite coatings on anodized magnesium alloys by electrochemical and chemical methods intended for biodegradable implants

The fabrication of hydroxyapatite (HAP)/MgO composite coatings on Mg alloy is crucial for enhancing the corrosion resistance and biocompatibility of biomedical implants. In this study, we aimed to investigate the effects of two different surface modification methods, i.e., electrochemical (electrodeposition, ED) and chemical (solution treatment, ST), on the phase structure, degradation properties, and biocompatibility of the composite coatings in comparison to the anodized coating. The surface morphologies and crystalline structures of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Subsequently, the degradation rate of the coatings in simulated body fluid were comprehensively evaluated by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electrochemical microscopy (SECM) tests. Additionally, in-vitro cell proliferation assays were employed to quantitatively assess the biocompatibilities of the coatings. The results showed that both ED and ST methods were effective in depositing HAP on anodized Mg alloy, resulting in different surface morphologies with hydroxyapatite layer thicknesses of 2.71 μm and 3.56 μm, respectively. In this way, the HAP-deposited coatings exhibited improved corrosion resistances and biocompatibilities compared with those of the anodized coating. Specifically, the ST-deposited composite film displayed superior degradability and biocompatibility which was attributed to its filiform surface morphology and thicker HAP layer. Overall, the present study demonstrates the potential of HAP/MgO composite coatings for biomedical applications, with implications for the development of advanced implant materials with improved performance and biocompatibility.

Bone-inspired hydroxyapatite nanowire-based bioceramics with superior mechanical performance

The fabrication of hydroxyapatite (HAP)-based bioceramics with similar mechanical performance to bone by traditional sintering process is still challenge. In bone tissues, HAP mineralized collagen fibrils and fiber-oriented microstructure play key roles in superior mechanical performance of bone. Inspired by the fiber-oriented microstructure and biomineralization process of bone, the mineralized HAP-based bioceramics (M-HAP) are successfully fabricated via directional assembly and biomimetic mineralization strategies based on ultralong HAP nanowires. The M-HAP bioceramics show comparable mechanical performance to human cortical bone in terms of flexural strength, tensile strength, Young's modulus and hardness, which could overcome the issue of mismatched mechanical properties between traditional HAP implants and host bone. In addition, the M-HAP bioceramics also exhibit good cytocompatibility in vitro and no obvious inflammatory response after implantation in vivo. Such bone-inspired bioceramics with both high mechanical property and good biocompatibility have great potential in the field of bone regeneration.

Construction of magnetic particles sprayed hydroxyapatite based bio-ceramic beads for selective fluoride removal

The current study concentrates on the fabrication of hydroxyapatite in an exploitable bead form with enhance defluoridation capacity (DC) and quick separation. Hence, magnetic iron oxide/alginate-gelatin/hydroxyapatite/β-cyclodextrin based beads (MAGHC bio-ceramic beads) were prepared and constructively utilized for fluoride retention from water. The responsible parameter for fluoride removal was performed by batch mode. The physic-chemical properties of the developed MAGHC bio-ceramic beads were characterized with different sophisticated instrumental methods namely EDAX, SEM and FTIR studies. The different adsorption kinetic and isotherms studies were carried out to fit experimental data of fluoride adsorption onto MAGHC bio-ceramic beads. The fluoride adsorption method was thermodynamically feasible and endothermic nature. Defluoridation by MAGHC bio-ceramic beads was majorly governed by electrostatic interaction and complexation. The reusable and actual real water sample test also investigated using developed MAGHC bio-ceramic beads. The results revealed that MAGHC bio-ceramic beads could reusable and efficiently remove fluoride from drinking water at field condition.

Alkaline-Activation Technique to Produce Low-Temperature Sintering Activated-HAp Ceramic

The fabrication of hydroxyapatite (HAp) ceramics prepared by existing conventional sintering requires high-temperature sintering of 1250 °C to 1300 °C. In this paper, the activated metakaolin (MK)/HAp specimens were prepared from varied mix design inputs, which were varied solid mixtures (different amounts of MK loading in HAp) and liquid-to-solid (L/S) ratios, before being pressed and sintered at 900 °C. Phase analysis, thermal analysis, surface morphology, and tensile strength of the specimens were investigated to study the influences of the Al, Si, Fe, Na, and K composition on the formation of the hydroxyapatite phase and its tensile strength. XRD analysis results show the formation of different phases was obtained from the different mix design inputs HAp (hexagonal and monoclinic), calcium phosphate, sodium calcium phosphate silicate and calcium hydrogen phosphate hydrate. Interestingly, the specimen with the addition of 30 g MK prepared at a 1.25 L/S ratio showed the formation of a monoclinic hydroxyapatite phase, resulting in the highest diametrical tensile strength of 12.52 MPa. Moreover, the increment in the MK amount in the specimens promotes better densification when sintered at 900 °C, which was highlighted in the microstructure study. This may be attributed to the Fe2O3, Na2O, and K2O contents in the MK and alkaline activator, which acted as a self-fluxing agent and contributed to the lower sintering temperature. Therefore, the research revealed that the addition of MK in the activated-HAp system could achieve a stable hydroxyapatite phase and better tensile strength at a low sintering temperature.

Fabrication of Hydroxyapatite with Bioglass Nanocomposite for Human Wharton's-Jelly-Derived Mesenchymal Stem Cell Growing Substrate.

Recently, composite scaffolding has found many applications in hard tissue engineering due to a number of desirable features. In this present study, hydroxyapatite/bioglass (HAp/BG) nanocomposite scaffolds were prepared in different ratios using a hydrothermal approach. The aim of this research was to evaluate the adhesion, growth, viability, and osteoblast differentiation behavior of human Wharton’s-jelly-derived mesenchymal stem cells (hWJMSCs) on HAp/BG in vitro as a scaffold for application in bone tissue engineering. Particle size and morphology were investigated by TEM and bioactivity was assessed and proven using SEM analysis with hWJMSCs in contact with the HAp/BG nanocomposite. Viability was evaluated using PrestoBlueTM assay and early osteoblast differentiation and mineralization behaviors were investigated by ALP activity and EDX analysis simultaneously. TEM results showed that the prepared HAp/BG nanocomposite had dimensions of less than 40 nm. The morphology of hWJMSCs showed a fibroblast-like shape, with a clear filopodia structure. The viability of hWJMSCs was highest for the HAp/BG nanocomposite with a 70:30 ratio of HAp to BG (HAp70/BG30). The in vitro biological results confirmed that HAp/BG composite was not cytotoxic. It was also observed that the biological performance of HAp70/BG30 was higher than HAp scaffold alone. In summary, HAp/BG scaffold combined with mesenchymal stem cells showed significant potential for bone repair applications in tissue engineering.

In vitro bioactivity and antibacterial performances of atmospheric plasma sprayed c-axis preferential oriented hydroxyapatite coatings

Atmospheric plasma spraying (APS) is widely used in the fabrication of hydroxyapatite (HA) coating due to the advantages of low-cost, simple operation and it can be used to fabricate coatings with controllable structure. Despite all these advantages, the application of APS deposited HA coating for long-term use is limited by its low crystallinity, low phase purity and poor antibacterial property efficiency. Herein, HA coatings with high crystallinity, phase purity and c-axis crystalline orientation were fabricated by APS. In vitro cell, culture testing suggested that the c-axis oriented HA coating was more effective to promote the proliferation of osteoblasts cells compared with other coatings. The antibacterial activity of HA coating against the bacteria indicated that the c-axis oriented HA coating restrained the bacterial adhesion, and the antibacterial effect of the E. coli bacteria was more pronounced than that of the S. epidermidis bacteria. This study suggests that the HA coatings with the specific c-axis crystalline orientation are available for their potential applications for orthopedic and dental implantation.

Synthesis of copper-silver doped hydroxyapatite via ultrasonic coupled sol-gel techniques: structural and antibacterial studies

Fabrication of hydroxyapatite (HA) via doping with metal ions to enhance its antibacterial properties has attracted much interest. The present study aims to synthesize copper-silver doped hydroxyapatite particles (Cu-Ag doped HA) with an improved antibacterial activity through a sol-gel technique coupled with ultrasonic irradiation. The doping materials consist of Cu2+ and Ag+ ions with precursor molar ratios of 0.0, 0.25, 0.50, 0.75 and 1.0. The physicochemical properties of Ca9.0Cu1.0-xAgx(PO4)6(OH)2 samples were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy coupled with energy dispersive X-ray analysis (TEM-EDS). Characterization studies revealed that Cu2+ and Ag+ ions were incorporated into a hexagonal framework of HA. The main functional groups were identified as hydroxyl (OH−) and phosphate (PO43−) moieties. Their morphologies were rod-shaped with various diameters and particle size distributions, depending on the molar ratio of Cu2+ to Ag+. Antibacterial activity was evaluated using an agar well diffusion method against Staphylococcus epidermis, S. aureus, Bacillus subtilis, B. cereus, and Pseudomonas aeruginosa. It was found that Cu-Ag doped HA is an effective antibacterial agent. Ca9.0Cu0.5Ag0.5(PO4)6(OH)2 showed the best antibacterial performance against all bacterial strains with inhibition zones ranging from 13 to 17 mm, indicating its suitability as an antibacterial material in biomedical applications.

Biomimetic fabrication of hydroxyapatite hollow spheres with polyoxyethylene chain-containing quaternary ammonium salt cationic Gemini surfactant as template

ABSTRACTThis paper reports a biomimetic fabrication of hydroxyapatite (HAp) with a hollow spherical three-dimensional architecture, using Ca(NO3)2 and (NH4)3PO4 as the starting materials, and a polyoxyethylene chain-containing quaternary ammonium salt cationic Gemini surfactant [C12C2C12 (EO)] as the template. The effects of the surfactant concentration, aging time, and temperature on the morphology and the degree of crystallinity of HAp were investigated. We also proposed a possible mechanism for the formation of hollow spherical HAp. The results showed that the cationic Gemini surfactant was the most important parameter for the formation of spherical HAp. We obtained uniform well-defined hollow spherical HAp with semidiameter about 1.5 μm, using 0.1% mass fraction of template, at 37°C for 7 days.

Sintering Behaviour of Calcium Phosphate Based Powders prepared by Extraction Method

Hydroxyapatite (HA) is widely used in biomedical implant applications, due to its bioactive, biodegradable and osteoconductive properties. The fabrication of HA by chemical routes is fairly complicated. Extraction of HA from the bovine bone is economic and bio compatible and besides it is easy to obtain. The HA extracted from the bovine bone have most properties of the origin bone. In addition to this, bone grafting potential is better than HA produced by chemical route. The aim of this work is to understand sintering/densification behavior of HA produced from bovine bone (by Archimedes’ principle kit), the microstructure of the sintered bodies (by SEM-EDS) and their mechanical properties (hardness and fractured toughness). Densifications of compact HA samples from natural bone with and without additive were investigated. Phase identification of the raw cow bone and sintered compacts were determined by X-ray diffraction technique.

Electrophoretic‐deposited HAP nano‐layer as a QCM‐D sensor coating: effects of suspension concentration and electric‐field strength

This study investigates the fabrication of hydroxyapatite (HAP) nano-coating on a gold–quartz crystal sensor used for quartz crystal microbalance with dissipation (QCM-D) measurement using an electrophoretic deposition technique. Surface morphology and thickness of the HAP coating are examined via scanning electron microscopy and nano-indention testing. Its repeatability is verified via QCM-D testing. Results show that electrophoretic deposition with ultrasonic treatment is feasible and cost-effective for fabricating nano-thick HAP coatings on a QCM-D gold–quartz crystal sensor surface. Both suspension concentration and electric-field strength influence the compactness of HAP coatings. There exists a non-linear relationship between HAP coating compactness and the suspension concentration/electric-field strength. When the HAP suspension concentration is 30 g/l and the applied electric-field strength is 150 V/cm, the HAP coating on the QCM-D gold–quartz crystal sensor surface is uniform and compact with a thickness of 35 nm and is tightly bonded to the sensor surface. The obtained HAP-coated sensor is thus suitable for QCM-D measurement.

The usability of ark clam shell (Anadara granosa) as calcium precursor to produce hydroxyapatite nanoparticle via wet chemical precipitate method in various sintering temperature.

This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35–69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries .

Fabrication of Hydroxyapatite Disc as Filtration Membrane in Waste Water Treatment System

Due to the increase of industrial activities both at local and national level, the quality of water in Indonesia is significantly degraded by time. Heavy metal wastes from industrial activities have become serious contaminants in the water. The contamination dangers human’s health since most people living near the river-bank still use the water to fulfill their daily needs. In this paper, we present the fabrication of Hydroxyapatite (HA) disc as a filtration medium in waste water treatment system. HA is one of biomaterial which can be derived from animal’s bone and is capable to absorb dangerous heavy-metal contaminants such as lead (Pb) in the water. Our produced HA was made by extracting cortical bovine bones into cortical bone HA powder. The cortical bovine bones were processed using physical method by heating the bones at 900oC to gained powder then followed by forming green bodies and sintering at 1000oC and 1400oC. Those powders were then pressed into a disc form and will be used as filtration media in HA modular purifier. SEM/EDX results show the disk surface has interconnected micropores and Ca/P ratio value on sintered HA disc at 1000oC and 1400oC are 2.20 and 1.85, respectively.

Fabrication of hydroxyapatite on pure titanium by micro-arc oxidation coupled with microwave-hydrothermal treatment

Porous hydroxyapatite (HA)-containing composite films were prepared by a novel method consisting of micro-arc oxidation (MAO) combined with microwave-hydrothermal (M-H) treatment. The morphology, composition and phase composition of the bioactive films were investigated with scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction. MTT assay was carried out to investigate the in vitro effects of the different surfaces on bone integration properties. The prepared MAO films consisted mainly of anatase, rutile and tricalcium phosphate along with amorphous calcium (Ca) and phosphorus (P) phases. The M-H-treated composite films were composed primarily of anatase, rutile and HA. As the time and temperature of the M-H treatment increased, the number of HA crystals gradually increased. Using the M-H method, HA was obtained at a lower temperature and in a shorter period of time compared to the conventional hydrothermal method. The results suggest that the M-H method significantly decreases the hydrothermal reaction temperature and also greatly shortens the reaction time. Due to the nanocrystallinity and porosity of the prepared composite films, the method presented here shows promise for the formation of bioactive materials for medical applications.

光造形法によるハイドロキシアパタイト製傾斜気孔人工骨の作製

光造形法によるハイドロキシアパタイト製傾斜気孔人工骨の作製

Fabrication of Hydroxyapatite and Observation of Nanoparticles Entering into Cells

Unambiguous and thorough knowledge of interactions between cells and nanoparticles was necessary for applications of nanoparticle in living system. In this report we presented systematic studies of fabrication of inorganic nanoparticles and the application of entering into cells. Size distribution, zeta potential and transmission electron microscope (TEM) were performed to characterize the nanoparticles structure and define the mechanism by which nanoparticles are capable of entering into cells. The study revealed nanoparticles can entered cells via penetrating through the lipophilic bilayer, which should be paid attention to for inspirational value insome application researches and will be harmful in other cases.

Fabrication of hydroxyapatite with controlled morphology in a micro-reactor

A flow-micro-reactor system was employed to fabricate hydroxyapatite (HAp) in order to mimic the interface between calcium and phosphate solutions on a wet chemical procedure. The mixing ratio of calcium nitrate tetrahydrate and diammonium hydrogenphosphate solution was set to the stoichiometric atomic ratio HAp, 1.67, while pH value of the product suspension was varied from 6.4 to 10.0. The product morphology was changed from nano-sheet type to nano-particle type via nano-rod one, while their size was decreased from 100–500 nm to 50 nm. All as-prepared samples, irrespective of pH value of the resultant suspension, consisted of HAp, predominant phase, octacalcium phosphate (OCP), and dicalcium phosphate dihydrate (DCPD) or dicalcium phosphate anhydrate (DCPA). A batch system using the same solutions yielded very similar results, which confirmed that the reactions in this micro-reactor well reproduced a large-scale mixing system. Calcining sample obtained from pH 6.4 suspension for 2 h at lower temperatures (<400°C) lead to decomposition of DCPD, DCPA, and OCP. Trace tricalcium phosphate (TCP) appeared on calcination above 400°C. HAp remained the predominant phase throughout the process. After calcination at 600°C, no other phases than HAp and TCP were present in the product. The analyzed ratio Ca/P (1.38) implied that those crystalline phases were highly Ca-deficient, and that amorphous calcium phosphates were involved in both as-prepared and calcined sample pH 6.4.

Fabrication of hydroxyapatite and TiO 2 nanorods on microarc-oxidized titanium surface using hydrothermal treatment

AC-type microarc oxidation (MAO) and hydrothermal treatment techniques were used to enhance the bioactivity of commercially pure titanium (CP-Ti). The porous TiO 2 layer fabricated by the MAO treatment had a dominant anatase structure and contained Ca and P ions. The MAO-treated specimens were treated hydrothermally to form HAp crystallites on the titanium oxide layer in an alkaline aqueous solution (OH-solution) or phosphorous-containing alkaline solution (POH-solution). A small number of micro-sized hydroxyapatite (HAp) crystallites and a thin layer composed of nano-sized HAps were formed on the Ti-MAO-OH group treated hydrothermally in an OH-solution, whereas a large number of micro-sized HAp crystallites and dense anatase TiO 2 nanorods were formed on the Ti-MAO-POH group treated hydrothermally in a POH-solution. The layer of bone-like apatite that formed on the surface of the POH-treated sample after soaking in a modified simulated body fluid was thicker than that on the OH-treated samples.

Fabrication of Hydroxyapatite with Three-dimensional Pore Frame by Colloidal Template Method

SiO2 colloidal template was prepared through Stber method,followed by gravitational sedimentation.Hydroxyapatite(HA) with highly ordered three-dimensional pores was fabricated through infiltrating the template with HA precursor,sintering and then removing the template by immersing in NaOH solution.The samples were characterized by X-ray diffraction(XRD),transmission electron microscope(TEM),field emission scanning electron microscope(FESEM).The effects of the concentration and amount of HA precursor,and the time of immersion in NaOH solution on the preparation technique,the porous structure and the porosity were investigated.The results show that the Zeta potential of SiO2 spheres increase after surface modification by H2O2,thus improving the order degree of the silica colloidal template.The sizes of SiO2 colloid spheres and the pores formed by dissolved spheres are about 250nm and 200nm,respectively.There are a great number of micro-pores with dimension of 20nm on the wall of the HA pore formed by removing SiO2 spheres.The well-ordered HA with three-dimension pores are fabricated on the condition that the HA precursor concentration is 0.8mol/L,the volume ratio of HA precursor to the whole template is 30%,immersion in 4mol/L NaOH solution for 3d.

Fabrication of hydroxyapatite with highly ordered macroporous frame by colloidal templating method

Three-dimensional, highly ordered macroporous frame of hydroxyapatite has been fabricated via a template-assisted colloidal processing technique. In the present method, colloidal template was first prepared with SiO 2 spheres by gravitational sedimentation, which was then infiltrated with hydroxyapatite precursor prepared by the sol–gel process. The resulting hydroxyapatite replicated the three-dimensionally ordered macroporous structure of SiO 2 template. Modified by H 2O 2, the SiO 2 spheres could be packed into better ordered templates. After removal of the template by immersing in NaOH solution, the well-ordered macroporous frame made from HA was obtained. The arrangement of the pore structure was hexagonal close-packed and pore sizes could be controlled by changing the sizes of SiO 2 spheres. The resulting highly ordered macroporous frame of hydroxyapatite could have potential applications in the biomedical field.

Electrophoretic deposition of composite hydroxyapatite–silica–chitosan coatings

Electrophoretic deposition (EPD) method has been developed for the fabrication of nanocomposite silica–chitosan coatings. Cathodic deposits were obtained on various conductive substrates using suspensions of silica nanoparticles in a mixed ethanol–water solvent, containing dissolved chitosan. Co-deposition of silica and hydroxyapatite (HA) nanoparticles resulted in the fabrication of HA–silica–chitosan coatings. The deposition yield has been studied at a constant voltage mode at various deposition durations. The method enabled the formation of coatings of different thickness in the range of up to 100 μm. Deposit composition, microstructure and porosity can be varied by variation of HA and silica concentration in the suspensions. It was demonstrated that EPD can be used for the fabrication of HA–silica–chitosan coatings of graded composition and laminates. The method enabled the deposition of coatings containing layers of silica–chitosan and HA–chitosan nanocomposites using suspensions with different HA and silica content. Obtained coatings were studied by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy and energy dispersive spectroscopy. The mechanism of deposition is discussed.