Characteristics Of Hydroxyapatite Research Articles

Optically stimulated luminescence properties of chicken eggshell derived hydroxyapatite for dosimetry applications

AbstractThis study investigated the optically stimulated luminescence (OSL) characteristics of hydroxyapatite (HAp) derived from chicken eggshells, a readily available bio-waste, for low-level radiation dosimetry applications which is less explored. The eggshells were employed as a calcium source in HAp synthesis. The X-ray diffraction and Fourier transform infrared spectroscopy results confirmed its purity and crystallinity. The OSL properties of the synthesized HAp demonstrated excellent reproducibility, reusability, and dose linearity up to 20 Gy, with a measurable dose range of 22 mGy. The favorable OSL characteristics, combined with the utilization of waste materials, offer significant advantages for environmental and medical radiation monitoring.

Optimizing biomimetic hydroxyapatite coating on Ti-6Al-6Mo alloy: influence of immersion time

This study investigates the formation and characteristics of hydroxyapatite (HAp) coating on Ti-6Al-6Mo alloy through immersion in a supersaturated calcification solution (SCS) for 3, 7, and 14 days. X-ray diffraction (XRD) and secondary electron microscopy (SEM) with electron dispersive spectroscopy (EDS) were used to identify the phases and characterize the morphology and composition of the HAp layer. Atomic force microscopy (AFM) and contact angle tests were used to evaluate the surface properties, while potentiodynamic corrosion testing in Hanks’ solution was used to assess corrosion behavior. It is confirmed that the sample immersed for 14 days formed an HAp layer on the Ti-6Al-6Mo substrate with a Ca/P ratio of 2.5, approaching the ideal value of 1.67. This HAp film exhibits a smooth and homogeneous crystal structure, with a surface roughness of 31.47 nm and an appreciable corrosion rate of 0.0005 mm y−1. This study signifies the impact of immersion time on the microstructural properties and biocompatibility of biomimetic HAp coatings applied to Ti-6Al-6Mo alloy, contributing to the progress of HAp coatings in biomedical engineering.

Hydroxyapatite Characteristics from Snakehead Fish (Channa striata) Bone via Alkali Treatment followed by Calcination Method

Hydroxyapatite Characteristics from Snakehead Fish (Channa striata) Bone via Alkali Treatment followed by Calcination Method

AgNPs-TiO2NPs doped calcined hydroxyapatite for effective removal of ibuprofen and Acetaminophen

ABSTRACT Pharmaceuticals as an increasing water contaminant pose major hazards to water quality and human health. Hydroxyapatite (HAp) has shown promise in the treatment of many contaminants, although it could be improved. The adsorption capacity of silver and titanium dioxide nanoparticles doped calcined HAp (AgNPs-TiO2NPs@calcined HAp) for acetaminophen (ACT) and Ibuprofen (IBP) was investigated in this study. Fourier Transform Infra-Red (FTIR) spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) were used to characterise the AgNPs-TiO2NPs@calcined HAp. Both AgNPs and TiO2NPs absorbed maximally at 376 and 366 nm, respectively. The FTIR of AgNPs-TiO2NPs@calcined HAp revealed FTIR peaks at 1425, 925 and 590 cm−1 corresponding CO3 2- and PO4 3- characteristics of HAp, with XRD pattern revealing crystalline hexagonal-shaped HAp having a particle size of 31.72 ± 10.19 nm. The BET surface area and pore volume increased with doping to 446.11 ± 6.30 m2g−1 and 0.0167 ± 0.0024 cm3g−1, respectively while pore radius reduced slightly to 3.12 ± 0.08 Å indicating a microporous structure of the adsorbent. The surface of AgNPs-TiO2NPs@calcined HAp favoured adsorption of IBP and ACT at pH 2 and 9, respectively. Adsorption data of both drugs best fitted pseudo-second-order kinetics with equilibrium established at 50 and 60 min for ACT and IBP respectively. The adsorption ACT and IBP on AgNPs-TiO2NPs@calcined HAp followed an S-shaped pattern, with Langmuir and Freundlich isotherms best-representing removal of ACT and IBP, respectively. The adsorption capacities ( q max ) ranged from 20.72 to 76.92 mgg−1 for ACT and 114.97 to 188.00 mgg−1 for IBP. The adsorption process was exothermic (-ΔH) and spontaneous (-ΔG) with a decreased degree of randomness (-ΔS). The adsorption mechanism was physisorption for ACT and alternated between physisorption and chemisorption for IBP. The adsorptive performance of AgNPs-TiO2NPs@calcined HAp for ACT and IBP removal implies it is a better adsorbent than most previously reported in the literature.

Effect of Ag-doping on the thermal features of hydroxyapatite

Effect of Ag-doping on the thermal features of hydroxyapatite

Influence of iron doping towards the physicochemical and biological characteristics of hydroxyapatite

Hydroxyapatite (HAP) is the naturally occurring mineral form of calcium apatite and the most studied material as a bone substituent. Considering HAP's inherent properties, this study explored changes in HAP's characteristics from doping with other metals such as Fe. To form pure HAP and Fe-HAP with different amounts of Fe, we used the hydrothermal approach, and the composites that formed were thoroughly analyzed for their crystallinity, surface bonding, morphology, magnetic behavior, mechanical strength, biocompatibility, hemocompatibility, and in vitro cytotoxicity. The powder XRD studies confirmed the samples' crystallinity, and the lowest crystalline size was 19.7 nm in 10Fe-HAP. The FTIR analysis confirmed the formation of HAP by the hydroxyl, phosphate, and carbonate groups. The FESEM demonstrated that the morphology of the pure HAP was rod-shaped, which transformed into spheres after Fe doping. The EDS analysis confirmed the successful formation of HAP and Fe-HAP composites. The magnetic studies indicated the diamagnetic behavior of the pure HAP, while the Fe-doped HAPs had a superparamagnetic nature with saturation magnetizations (Ms) of 2Fe-HAP, 4Fe-HAP, and 10Fe-HAP at 0.0062, 0.0092, and 0.029 emu/g respectively. Assessment of the mechanical properties, biocompatibility, hemocompatibility, and cytotoxicity indicated that the Fe-doped HAPs were superior to the pure HAP, and among the Fe-HAPs, the 10Fe-HAP) had the highest amount of Fe and the best characteristics. The studies also indicated that Ca2+ interactions influenced the cells via HAP doping with that of Fe, equally increasing the physicochemical and biological properties.

Characteristics of hydroxyapatite from buffalo bone waste synthesized by precipitation method

Hydroxyapatite (HA), Ca10(PO4)6(OH)2, is the most widely used ceramic biomaterials. It is a mineral found in natural teeth, bone and hard tissue. In this paper, we present a synthesis and characterization for obtaining HA by wet precipitation. This study mainly focuses on the use of bio-waste materials, i.e., buffalo bones to obtain HA. In order to synthesized HA from buffalo bones, we use Ca(OH)2, H20 and H3PO4 as the starting precursors. The material was sintered at temperatures of 650 °C, 850 °C, and 1050 °C for 7 hours to improve its particle size distribution. Identification of functional group using FTIR shows absoption namely at wavenumber values of 3699.20, 3787.92 and 3706.91 cm−1 which indicate hydroxyl group (OH). Phosphate band were identified by peak 1022.20 and 1118.63 cm−1 and 1215.06 to 1459.31−1cm which indicates carbonate group. Ratio of Ca/P for synthesized HA is about 1.67. XRD pattern results indicated that the synthesized buffalo bone HA closely correspond to commercial HA phase.

Time-domain THz spectroscopy of the characteristics of hydroxyapatite provides a signature of heating in bone tissue.

Because of the importance of bone in the biomedical, forensic and archaeological contexts, new investigation techniques are constantly required to better characterize bone ultrastructure. In the present paper, we provide an extended investigation of the vibrational features of bone tissue in the 0.1-3 THz frequency range by time-domain THz spectroscopy. Their assignment is supported by a combination of X-ray diffraction and DFT-normal modes calculations. We investigate the effect of heating on bone tissue and synthetic calcium-phosphates compounds with close structure and composition to bone mineral, including stoichiometric and non-stoichiometric hydroxyapatite (HA), tricalcium phosphate, calcium pyrophosphate and tetracalcium phosphate. We thus demonstrate that the narrow vibrational mode at 2.1 THz in bone samples exposed to thermal treatment above 750 °C arises from a lattice mode of stoichiometric HA. This feature is also observed in the other synthetic compounds, although weaker or broader, but is completely smeared out in the non-stoichiometric HA, close to natural bone mineral composition, or in synthetic poorly crystalline HA powder. The THz spectral range therefore provides a clear signature of the crystalline state of the investigated bone tissue and could, therefore be used to monitor or identify structural transitions occurring in bone upon heating.

The ultrasound effect on the morphological properties of hydroxyapatite

The present study considers the morphological and dispersity characteristics of hydroxyapatite (HAp) samples synthesised through the ultrasound-assisted hydrothermal method with additional pressure treatment. The samples were analyzed by the X – Ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption. The ultrasound effect on the HAp morphologiy and dispersity was studied. The pressure assisted ultrasonic treatment made possible obtaining HAp samples with different morphology from rods and flakes to particles with irregular shape close to spherical. Also pressure assisted ultrasonic treatment able to increase the porosity of HAp materials.

Fabrication and evaluation of hydroxyapatite-chitosan scaffold via simulated body fluid biomimetic mineralization

This research aimed to fabricate a hydroxyapatite (HA)-chitosan scaffold via simulated body fluid (SBF) biomimetic mineralization and determine how mineralization time affects scaffold construction and cell compatibility. The HA-chitosan scaffolds were fabricated by freeze-drying technique and then subjected to precalcification, also known as alternative soaking method. Afterward, precalcificated scaffolds were placed into the SBF to conduct the mineralization process. Mineralization time was set at 7, 14, and 21 days, corresponding to three experimental groups. Pure chitosan scaffolds acted as the control group, and the physical and chemical properties of the four groups were tested. Osteogenic-induced adipose-derived stem cells (ADSCs) were seeded into the scaffolds to investigate the scaffolds' cell compatibility. The mineral substance of the 14-day group exhibited a uniform distribution. The crystal composition of the mineral substance suited the HA's features. The compressive elastic modulus increased along with the extension of mineralization time. The 21-day group showed a statistically significant increase in compressive elastic modulus compared with the control group (P < 0.05). The cell proliferation level of the 14-day group was significantly the highest among the three experimental groups (P < 0.05). The calcium ion and the type I collagen had the highest secretion amount when the cells were seeded into the 14-day group. The SBF biomimetic mineralization method can be used to fabricate HA-chitosan bone-tissue-engineering scaffolds. The biological compatibility, as well as the chemical and physical properties, reached the optimum levels at day 14.

English

Oyster shell is basically made of calcium carbonate. An attempt is made to convert calcium carbonate of oyster shell to hydroxyapatite (HA), a substitute material for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. In the present work, hydroxyapatite (HA) was successfully synthesized by wet precipitation method using Ca (NO3)2, and (NH4)2HPO4, and NH4OH as starting materials. The oyster shell was found to decompose within 10000C to all the carbonate phases. The calcined oyster shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichiometry to produce fine hydroxyapatite (HA) as filter cake with a Ca/P molar ratio of 1.67. The dried HA powder was extremely pure. Different characterization techniques were adopted both for calcined oyster shell and HA by scanning electron microscopy (SEM), X-ray diffractometer (XRD), fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analyzer (TGA). The absorption bands corresponding to phosphate and hydroxyl functional group which are characteristics of hydroxyapatite were confirmed by FTIR. Besides its effectiveness in bone substitution, the prepared HA holds great potential in the field of dental application.

Effects of temperature on the preparation and characteristics of hydroxyapatite and its adsorptive properties toward lead

This shows how the calcination temperature affects the hydroxyapatite composition and structure and how Pb2+is fixed on the external surface of its particles.

Interconnectivity of Bioceramic Scaffolds with Different Porous Structures and Their Fluid Velocity Distribution Analyzed by Micro-CT Computer Modeling

Pore interconnectivity is a key parameter for bone tissue engineering scaffolds, which controls penetration of body fluid with proteins and cells, and tissue ingrowth. The present study investigated the porous characteristics of hydroxyapatite (HA) scaffolds prepared via three processes (HA sphere packing, wax sphere-leaching and HA fiber aggregation) by micro-computed tomography (μCT) from following three procedures: (1) modeling of the porous structure by image reconstruction; (2) analysis of porosity along longitudinal direction; and (3) simulation of fluid flow across the scaffold by finite element analysis (FEA). Image analyses revealed that, the scaffolds prepared by the above two methods featured relatively regular porosity distributions, whereas that by HA fiber aggregation had an irregular distribution. Fluid velocity distribution by FEA suggested that scaffolds prepared by HA sphere packing and wax 72 无 机 材 料 学 报 第 30卷 sphere leaching readily allowed penetration of fluid due to their favorable pore interconnectivity. The fluid velocity vector distribution predicted that circular flows dominated near the pore wall in the scaffold prepared by wax sphere leaching. These circular flows may impede the material exchange between cells attached to the pore wall and the body fluid, which may illustrate that the inferior in vivo osteogenic activity of scaffolds prepared by wax sphere leaching when compared with those produced by HA sphere packing.

Box-Behnken Design of Experiments Investigation of Hydroxyapatite Synthesis for Orthopedic Applications

Physicochemical properties of hydroxyapatite (HAp) synthesized by the chemical precipitation method are heavily dependent on the chosen process parameters. A Box-Behnken three-level experimental design was therefore, chosen to determine the optimum set of process parameters and their effect on various HAp characteristics. These effects were quantified using design of experiments (DoE) to develop mathematical models using the Box-Behnken design, in terms of the chemical precipitation process parameters. Findings from this research show that the HAp possessing optimum powder characteristics for orthopedic application via a thermal spray technique can therefore be prepared using the following chemical precipitation process parameters: reaction temperature 60 °C, ripening time 48 h, and stirring speed 1500 rpm using high reagent concentrations. Ripening time and stirring speed significantly affected the final phase purity for the experimental conditions of the Box-Behnken design. An increase in both the ripening time (36-48 h) and stirring speed (1200-1500 rpm) was found to result in an increase of phase purity from 47(±2)% to 85(±2)%. Crystallinity, crystallite size, lattice parameters, and mean particle size were also optimized within the research to find desired settings to achieve results suitable for FDA regulations.

Effects of material morphology and processing conditions on the characteristics of hydroxyapatite and high-density polyethylene biocomposites by selective laser sintering

Hydroxyapatite (HA), a ceramic to which bone inherently bonds, incorporated into a polymer matrix enhances the bioactivity of implants. In order to rapid-manufacture bioactive implants, selective laser sintering (SLS) has been used to fabricate HA and high-density polyethylene (HDPE) composite (HA-HDPE). The properties of SLS-fabricated specimens have been investigated. The main aspects to be considered in the SLS technology are the properties of the materials used in the process and processing parameters (PPs). HA-HDPE composite specimens have been fabricated using five different powders with variations in particle size (PS), PS distribution, and five different laser PPs. The sintering height, the width, and the shrinkage of the specimens were determined and the effects of the particles and PPs on the physical properties were investigated. The HA-HDPE specimens were found to be highly porous and the sintered density and porosity of the specimens were influenced by the PS and PPs. The interparticle connectivity and the pore size range of the specimens were found to be predominantly determined by the PS and to a lesser extent also influenced by the PPs. The strength of these specimens and the relationship with porosity are discussed.

Bone Mineral and Collagen Quality in Iliac Crest Biopsies of Patients Given Teriparatide: New Results from the Fracture Prevention Trial

Evidence suggests that both bone mineral density and bone quality should be taken into account when assessing bone strength and fracture risk. Bone quality is a multifactor entity, of which bone architecture and material properties are two important components. Matrix mineralization, hydroxyapatite characteristics, and collagen cross-link ratio are key determinants of material properties. Fourier transform infrared imaging (FTIRI) yields data on these characteristics from bone sections. We sought to determine collagen cross-link ratios and matrix mineralization of bone from patients randomized to teriparatide [recombinant human PTH (1-34)] treatment using FTIRI. The Fracture Prevention Trial was randomized, double blind, and placebo-controlled. The trial was conducted at global clinical research centers. Patients consisted of postmenopausal women with osteoporosis. Patients were randomized to receive daily sc injections of placebo (n = 12) or 20 microg (n = 13) or 40 microg (n = 13) teriparatide. Biopsies were obtained after 12 months of treatment or at the end of treatment (range, 19-24 months for end of treatment paired biopsies). Biopsies were analyzed by FTIRI to determine the matrix mineralization (mineral to matrix), mineral crystallinity, and collagen cross-link ratio (pyridinoline/dehydrodihydroxylysinonorleucine) with a spatial resolution of approximately 6.3 microm. Patients administered teriparatide 20 and 40 microg/d exhibited significantly lower matrix mineralization, mineral crystallinity, and collagen cross-link ratio when compared with placebo. These findings indicate that the bone-forming effect of teriparatide results in bone with a molecular profile reminiscent of younger bone.

Experimental design approach in the synthesis of hydroxyapatite by neutralization method

Physicochemical properties of hydroxyapatite (HAP) synthesized by neutralization method are heavily dependent on the process variables. A Plackett–Burman two-level experimental design was therefore, chosen to screen a large number of variables and to determine their effect on HAP characteristics. The sorption of cadmium ions on HAP was studied as well. Of six selected variables (temperature, mixing speed, reactant concentration, addition rate, presence of inert atmosphere and aging time), temperature has shown the strongest influence on HAP structural and sorption properties. Smaller crystallites, lower crystallinity and higher specific surface area lead to higher sorption of cadmium ions. Room temperature and no aging are preferable conditions for the synthesis of HAP with the highest sorption efficiency.

Cadmium immobilization by hydroxyapatite

The contamination of air, soil and water by cadmium is a great environmental problem. If cadmium occurs in nature in ionic form, soluble in water, it easily enters into the food chain. Hydroxyapatite (HAP), Ca-\o(POA)e(OH)2 is a sparingly soluble salt and an excellent matrix for the removal of heavy metals from solutions. Considerable research attention has been paid to the bond between Cc/2+ ions and synthetic hydroxyapatite of known composition. The sorption mechanism is complex. The dominant process is ion exchange, but surface adsorption, surface complexation and coprecipitation can also contribute to the overall mechanism. The sorption capacity depends on the characteristics of hydroxyapatite itself and on the experimental conditions. Under optimum conditions a maximum capacity of 0.8 mol Cd2+/mol HAP can be achieved. HAP is a potential sorbent for the remediation of contaminated water and soil, for industrial waste treatment, and it is also referenced as a material that can be used as a barrier around waste depositories.

Biomimetic Method for Obtaining Hydroxyapatite

Coating of bioinerts or biotolerable materials with a bioactive layer, generally composed of hydroxyapatite (HA), has been currently used when one wishes to combine bioactivity and material properties. Coating methods include: plasma and flame spray, sputtering, electrophoresis and electrolysis. Except the electrolytic one, all other methods involve high working temperatures. Therefore, the physical and chemical characteristics of hydroxyapatite can be affected, with possible consequences on the behavior of the implanted material. A recently proposed method named biomimetic, can be employed to coat several types of substrates through precipitation of a hydroxyapatite layer. This approach imitates the biological natural conditions of hydroxyapatite formation, through control of temperature, pH and concentration of ionic species. In this work, barium titanate substracts were coated with hydroxyapatite and characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy.

Surface Characteristics of Hydroxy apatite and Adhesive Bonding. I. Surface Characterization

Abstract Adhesion to hydroxyapatite (HA), the mineral phase of calcified tissues, is important in cellular attachment and bonding of synthetic adhesive materials. The surface preparation of HA was found to affect the adhesion greatly. A pure synthetic HA was studied to examine the effect of commonly-used preparative techniques on surface morphology and activity. Surface grinding and polishing and organic acid etching gave rough surfaces that were hydrophobic. Etching with HC1 or HN03 and firing at 800°C gave hydrophilic surfaces. ISS, SIMS and ESCA studies showed various degrees of organic and inorganic contamination. Plasma cleaning removed hydrophobic contaminants but inorganic contamination from the plasma vessel increased as time of exposure was increased. It was evident that current preparative procedures give highly variable surfaces that would be expected to influence adhesion of both monomer-polymer adhesive systems and cells.