Papers by Keyword: Hydroxyapatite (HA)

Abstract: The effect of hydroxyapatite (HA) particle composition on the microstructure, Vickers microhardness, relative density and phases of β titanium nanocomposite prepared by powder metallurgy method were investigated experimentally. Hydroxyapatite particle in the range of 5 wt% to 25 wt% were mixed with Ti-35Nb-2.5Sn particles. The samples were pressed at 111 MPa and sintered at 900°C for 2 hours in a vacuum furnace. Result shows that by increasing the hydroxyapatite composition from 5 wt% to 15 wt %, the relative density and Vickers mirohardness increased. Phase analysis of raw materials was studied by XRD analysis and microstructure of composite by SEM.

Abstract: Nanocrystalline hydroxyapatite (HA) powder was synthesized by a simple heating process involving simple chemical reaction. The characterization of the produced powder showed that the powder is nanosize with particle in the range of 30-70 mm in diameter and almost evenly spherical in shape. The powder also has a high surface area of 43.16 m2/g. Field Emission Scanning Electron Microscopy (FESEM) observation showed the crystallite and particle size become bigger with an increment of calcination temperature, indicating increasing of crystallinity.. FESEM observation showed the particle size become bigger with an increment of calcinations temperature. It is in agreement with the crystallite size analysis, obtained by Scherer’s formula and particle size analysis, measured by nanoSizer. X-ray Diffraction (XRD) and Fourier Transform Infra Red Spectroscopy (FTIR) analyses exhibited the same result, where HA phase was clearly observed at at various temperatures up to 600 ̊C. However, at temperature more than 600 ̊C, Tri calcium phosphate (TCP) phase appeared suppressing the HA phase, producing biphasic calcium phosphate.

Abstract: 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.

Abstract: 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.

Abstract: It is arguable that successful bone tissue engineering (BTE) protocols relies heavily on scaffolds (i.e., for mechanical support, aid for 3D arrangement, allowing good nutrient and waste transport etc.). In this study, the consequence of adding a bentonite (B) layer between alumina foam (AF) and its hydroxyapatite (HA) coat scaffold is scrutinized by spatial characterization measurement (e.g., porosity, pore size, pore interconnectivity and compressive strength). Other than work on the said hydroxyapatite-bentonite coated alumina foam (HABCAF), spatial characterization efforts were also done for AF and HA coated AF (HACAF) scaffolds. Initially, AF scaffold was fabricated via the foam impregnation technique (FIT). Polyurethane (PU) foam was chosen as a template to ensure controlled porosity and guided pore interconnectivity within the resulting scaffold. HACAF and HABCAF are produced using AF scaffold skeleton, coated with HA and B (for HABCAF only) slurries of different viscosities. After drying and sintering stages, these scaffolds were tested. The results from composite coating show an increase of 40% in strength with the same pore size of PU foam. The HABCAF exhibited the highest compressive strength besides showing good interconnectivity and cell pores sizes (i.e., up to >500 μm). These results suggest that addition of B presents an interesting route in the making of good quality scaffolds for BTE applications.

Abstract: Hydroxyapatite (HAp), classified as bioceramic materials is the major mineral constituent of vertebrate bones and teeth. In this study, the effect of temperature on isolation and characterization of HAp from tilapia fish scales have been investigated. Scales were subjected to heat treatment at different temperatures (800°C and 1000°C) and microstructure of both raw and calcined scales were observed under Scanning Electron Microscopy (SEM). Thermo Gravimetric Analysis (TGA) and Energy Dispersive X-Ray Spectroscopy (EDX) results have revealed the best calcination temperature of tilapia scales to be 800°C due to the calculated calcium to phosphorous weight ratio (Ca/P). The Ca/P ratio for scales treated at 800°C and 1000°C were 1.598 and 1.939 respectively. The phase purity and crystallinity of produced HAp was further confirmed by X-Ray Diffraction (XRD) analysis. Based on the study, it can be concluded that tilapia fish scale is a good natural source of HAp with 800°C as the optimum calcination temperature in HAp production.

Abstract: A new method in situ for producing of biocompatible composites based on hydroxyapatite and oligomers of lactic and glycolic acid is described. Their thermo-mechanical, physical-chemical and biological properties are studied as well. The formation of bonds between hydroxyapatite with lactic and glycolic oligomers in composites are confirmed by IR spectroscopy of the samples, including those obtained in the Soxhlet apparatus. The formation of calcium-phosphate layer on the composite's surface containing hydroxyapatite was shown by SBF-investigation. The scaffolds based on lactic acid oligomer do not stimulate formation of a calcium-phosphate layer and they are subjected to destruction by the way of hydrolysis.

Abstract: The paper is dedicated to the research of calcium-phosphate coatings formed on the surface of the polymer layers (copolymer tetrafluoroethylene with vinylidene fluoride) by pulsed laser deposition. The calcium-phosphate coatings were formed using two different by composition targets. The morphology of the obtained coatings was analyzed by Scanning Electron Microscopy, the elemental composition was analyzed by Energy Dispersive Analysis, and the chemical composition was analyzed by Fourier Transform Infrared Spectroscopy.

Abstract: Ni deposited Hydroxyapatite powder was prepared by electroless deposition technique without sensitization and activation treatments. The composition and phase of deposition were studied. The surface morphologies and composition of initial pure HA powder, as received Ni deposited HA powder and compacted Ni deposited HA powder after sintering were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. The phases in the powder before and after sintering were investigated by x-ray diffraction (XRD). From the experiment, with the increase of reduction agent, the plating time becomes shorter and optimal concentration of reduction agent and powder ratio is 3:1. The result shows that Ni succesfully deposited on HA powder and confirmed by EDX result. The Ni grain size distribution of 75nm to 250nm can be clearly observed on the HA surface from the micrograph after sintering. Decomposition of hydroxyapatite into α-TCP (α tricalcium phosphate) and TTCP (tetracalcium phosphate) did not occur in nickel deposited HA before and after sintering. On the other hand, a sharp Ni peak were detected

Abstract: This study investigated the feasibility of manufacturing hydroxyapatite (HA)-based scaffolds using 3D printing technology by incorporating different binding additives, such as maltodextrin and polyvinyl alcohol (PVOH), into the powder formulation. Different grades of PVOH were evaluated in terms of their impact on the printing quality. Results showed that scaffolds with high architectural accuracy in terms of the design and excellent green compressive strength were obtained when the PVOH (high viscosity) was used as the binding additive for HA.