Hydroxyapatite Nanopowders Research Articles

High-performance ultrafiltration mixed-matrix membranes based on cellulose acetate and nanohydroxyapatite

The asymmetric cellulose acetate mixed-matrix membrane (MMM) filled with nanohydroxyapatite was prepared by a modified phase inversion method. To prevent the agglomeration of the hydroxyapatite nanocrystals and to obtain ultrafiltration composite membranes, a surfactant (12-hydroxystearic acid) was used. The hydroxyapatite nanopowder was dispersed in acetone-dissolved 12-hydroxystearic acid and then mixed homogeneously with acetone-dissolved cellulose acetate (CA). The process of addition of hydroxyapatite nanosuspension to CA solution resulted in asymmetric composite membranes with higher pure water flux and superior NaCl rejection in comparison to the CA membrane. The best performing composite membrane, the CHM-30 sample, shows a retention of 99.1% and a high water permeability of 34.96 L/m2 h bar. The results showed that the nanohydroxyapatite—cellulose acetate MMMs can be used in ultrafiltration applications.

Crystallization behavior of tantalum and chlorine co-substituted hydroxyapatite nanopowders

The crystallization behavior of tantalum and chlorine co-substituted hydroxyapatite nanopowders was examined. Results showed that combined processing by mechanical alloying and annealing is conducive to the structural changes and crystal growth. A series of nanocrystalline tantalum and chlorine co-substituted hydroxyapatite (Ta/Cl–HA) with different dopant contents were synthesized as a result of the progressive mechanochemical reaction. During the subsequent annealing, crystallization of the as-milled powders occurred, leading to a significant increase in the fraction of crystalline phase. TEM images revealed that the crystallized and doped nanopowders composed of crystalline nanoneedles with an average size of 61±26nm.

O2/Ar Plasma Treatment for Enhancing the Biocompatibility of Hydroxyapatite Nanopowder and Polycaprolactone Composite Film.

In this study we performed O2/Ar plasma treatment to remove the polycaprolactone on hydroxyapatite nanopowder and polycaprolactone (HAp-NP/PCL) composite film. After plasma ashing, the HAp-NP was exposed on the composite film. The 25 wt% HAp-NP/PCL treated with plasma showed the hydrophilic surface property with reducing the aging effect. The MTT and ALP results indicated that the plasma etching increased the biocompatibility of HAp-NP/PCL composite film. The present simple plasma etching technique can be applicable in a development of biomaterials.

Tensile and biocompatibility properties of synthesized nano-hydroxyapatite reinforced ultrahigh molecular weight polyethylene nanocomposite

Ultrahigh molecular weight polyethylene–based nanocomposites reinforced with nano-sized hydroxyapatite particles were fabricated using internal mixer and compression molding with different weight percent of the nano-hydroxyapatite. In this study, first, hydroxyapatite nanoparticles were synthesized by sol–gel. Then, the mechanical and biological properties of nanocomposites were studied by tensile test and proliferation and cell adhesion assays using MG-63 osteoblast cells, respectively. Results of the tensile test showed that incorporation of 50 wt% nano-hydroxyapatite led to a 345.64% and 57.58% increase in Young's modulus and yield strength (compared to the pure ultrahigh molecular weight polyethylene), respectively. The effect of the nano-hydroxyapatite powders on the MG-63 osteoblast cells behavior was compared to those of a composite (positive control) and a negative control samples. Scanning electron microscopy micrographs revealed that cell–biomaterial interaction was carried out on the surface of the nanocomposites with normal phenotypic shape. Results of MTT assay exhibited that all samples are biocompatible.

Structural and photoluminescence studies of Co2+ doped Ca–Li hydroxyapatite nanopowders

Co2+ doped Calcium–Lithium Hydroxyapatite (CLHA) nanopowders were prepared by mechanochemical synthesis and characterized by different techniques. From Powder XRD data, the crystal system belongs to hexagonal structure and lattice cell parameters, average crystallite size were evaluated. The morphologies of prepared samples were analyzed by using SEM and TEM studies. Optical and EPR data confirms that the doped Co2+ enter into host material as distorted octahedral site symmetry. PL studies of Co2+ doped CLHA nanopowders exhibit UV, blue and yellow emission bands. CIE chromaticity coordinates were also calculated from emission spectra of Co2+ doped CLHA nanopowders. Vibrational bands related to phosphate molecules, P–O–H and hydroxyl ions are observed in FT-IR spectra.

Synthesis of spongy-like mesoporous hydroxyapatite from raw waste eggshells for enhanced dissolution of ibuprofen loaded via supercritical CO2.

The use of cheaper and recyclable biomaterials (like eggshells) to synthesize high purity hydroxyapatite (HAp) with better properties (small particle size, large surface area and pore volume) for applications (in environmental remediation, bone augmentation and replacement, and drug delivery systems) is vital since high-purity synthetic calcium sources are expensive. In this work, pure and mesoporous HAp nanopowder with large pore volume (1.4 cm3/g) and surface area (284.1 m2/g) was produced from raw eggshells at room temperature using a simple two-step procedure. The control of precursor droplets could stabilize the pH value of the reaction solution, because of the size of the needle (of the syringe pump used for precursor additions) leading to production of HAp with high surface area and pore size. The as-produced HAp revealed high ibuprofen (as a model drug) loading (1.38 g/g HAp), enhanced dissolution and controllable release of the drug via solute-saturated supercritical carbon dioxide.

Synthesis of a Hydroxyapatite Nanopowder via Ultrasound Irradiation from Calcium Hydroxide Powders for Potential Biomedical Applications

Nanoscale hydroxyapatite based ceramics are a relatively new form of materials that are currently being investigated for a number of potential biomedical applications. This study reports on a straightforward wet chemical method that uses calcium hydroxide and phosphoric acid as precursors. After chemical synthesis a conventional thermal treatment was used to produce an ultrafine hydroxyapatite nanopowder. Varying ultrasonic power between zero and 400 W during the synthesis process produced crystallite sizes ranging from 15.4 nm down to 12.2 nm. The morphology of particles synthesized under the influence of ultrasonic irradiation was predominantly spherical and granular. Also present were a small number of irregular shaped plates. Energy dispersive spectroscopy revealed the samples had a Ca:P ratio of 1.66, which was very close to the ideal value of 1.67. FT-IR studies identified functional groups and confirmed the results of the X-ray diffraction data that the powders were indeed composed of nanoscale hydroxyapatite.

Mixed‐matrix membranes based on polyurethane containing nanohydroxyapatite and its potential applications

ABSTRACTIn this study, new asymmetric polyurethane (PU) mixed‐matrix membranes with different nanohydroxyapatite loadings were prepared via a dry–wet phase inversion method by the dispersion of hydroxyapatite (HA) nanoparticles in the PU matrix. The HA nanopowder was obtained by a wet chemical precipitation method; it showed an average crystallite size of 58.3 nm, a specific surface area of 261 m2/g, and a pore size of about 1.6 nm. The effects of the HA loading (10–50 wt %) on the PU membrane characteristics were studied. The scanning electron microscopy images revealed that the HA nanoparticles were well dispersed enough in the PU matrix. The average pore size in the top layer and porosity of the membranes slowly decreased, whereas the hydrophilicity and water permeability increased with increasing content of HA. The evaluation of the nanofiltration performance was performed by investigation of the NaCl rejection. The composite membranes had a higher salt‐removal capacity than the unfilled PU membrane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41813.

Spectroscopic Investigation and Magnetic Study of Iron, Manganese, Copper and Cobalt-doped Hydroxyapatite Nanopowders

Spectroscopic Investigation and Magnetic Study of Iron, Manganese, Copper and Cobalt-doped Hydroxyapatite Nanopowders

A physicochemical process for fabricating submicrometer hollow fluorescent spheres of Tb3+-incorporated calcium phosphate

The submicrometer hollow fluorescent spheres of Tb3+-incorporated calcium phosphate (CaP) were successfully fabricated by pulsed laser irradiation of the dispersion of carbon-integrated hydroxyapatite (HAp) nanopowders into Tb3+ ethanol solution.

Study of Corrosion Behavior of Polyuretane/nanoHidroxiapatite Hybrid Coating in Hank Solution at 25 °C

ABSTRACTThe study of corrosion behavior of polyurethane/nanohydroxyapatite hybrid coating in aerated Hank solution at 25 °C by Potentiodinamic and Electrochemical Impedance techniques was realized. The nanohydroxyapatite (nHA) powders were synthesized by ultrasonic assisted co-precipitation wet chemical method and then mixed with pure polyurethane (PU) during the polymerization. Results were supported by SEM morphologic characterization. Results showed that good corrosion resistance of hybrid coating, showing small corrosion product layer formation. Corrosion mechanisms are affected by an increasing of polarization resistance, promoting decreasing in the corrosion rates. Diffusion of ionic species was the governing mechanism in the corrosion behavior of polyurethane/nanohydroxyapatite hybrid coating.

The Interplay of manganese and nitrate in hydroxyapatite nanoparticles as revealed by pulsed EPR and DFT.

The interplay of oppositely charged substitutions in the structure of hydroxyapatite (HAp) nanopowders is investigated on the atomic level by pulsed electron paramagnetic resonance (EPR) technique and ab initio density functional theory calculations. Benefits of EPR to determine Mn(2+) ions in nano-HAp samples are demonstrated. A simple approach based on the measurements of electron spin relaxation times allowed observing the strong influence of fast-relaxing Mn(2+) ions on the relaxation characteristics of the nitrate ions (NO3(-)/NO3(2-)) incorporated in trace amounts. Based on the results of ab initio calculations, we show the propensity of Mn(2+) and NO3(-)/NO3(2-) to associate within the HAp crystal lattice. This could have a direct impact on the functional properties of the material especially to resorption and ion exchange. Furthermore, such an effect can increase a propensity of undesired impurities to incorporate into the doped nanocrystals.

EPR and Optical Studies of Fe3+-Doped Ca–Li Hydroxyapatite Nanopowder: Mechanochemical Synthesis

Fe3+-doped Ca–Li hydroxyapatite (CLHA) nanopowders were prepared by mechanochemical synthesis and characterized by different spectroscopic techniques. Powder X-ray diffraction data revealed that the crystal structure belongs to hexagonal and its lattice cell parameters, average crystallite sizes were evaluated. The morphologies of the prepared samples were analyzed by using scanning electron microscopy and transmission electron microscopy studies. Optical and electron paramagnetic resonance data confirmed that the doped Fe3+ enter into host material as distorted octahedral symmetry. Photoluminescence studies of Fe3+-doped CLHA nanopowders exhibit ultraviolet and blue emission bands. Commission Internationale de L’Eclairage chromaticity coordinates were also calculated from emission spectra of Fe3+-doped CLHA nanopowders. Vibrational bands related to phosphate molecules, P–O–H and hydroxyl ions are observed in the FT-IR spectra.

The effect of nanobioceramic reinforcement on mechanical and biological properties of Co-base alloy/hydroxyapatite nanocomposite.

The goal of the present research was to fabricate, characterize, and evaluate mechanical and biological properties of Co-base alloy composites with different amounts of hydroxyapatite (HA) nanopowder reinforcement. The powder of Co-Cr-Mo alloy was mixed with different amounts of HA by ball milling and it was then cold pressed and sintered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used. Microhardness measurement and compressive tests were also carried out. Bioactivity behavior was evaluated in simulated body fluid (SBF). A significant decrease in modulus elasticity and an increase in microhardness of the sintered composites were observed. Apatite formation on the surface of the composites showed that it could successfully convert bioinert Co-Cr-Mo alloy to bioactive type by adding 10, 15, and 20wt.% HA which have lower modulus elasticity and higher microhardness.

Preparation and Luminescent Properties of the La<sup>3+</sup> Doped Tb<sup>3+</sup>-Hydroxyapatite

In this paper, a rare earth metal terbium ion as the central metal ion, a nanohydroxyapatite powder of the lanthanum doped terbium was synthesis by precipitation with hydroxyapatite as ligand. The sample was characterized by infrared spectrum, fluorescence spectrum and X ray diffraction instrument, and the thermal properties and fluorescence properties, structure of powderes were discussed. A nanohydroxyapatite powder of the lanthanum doped terbium achieves the maximum luminous intensity, when the La3+ doping concentration of Tb3+ was HAP 5% (La3+ and Tb3+ mole fraction ratio) devices. Rare earth powder of the lanthanum doped terbium hydroxyapatite has the stability chemical properties, the luminescence properties and good biological activity, the rare earth powder has good luminescent properties can be used in preparation of a good light emitting device. At the same time a nanohydroxyapatite powder of the lanthanum doped terbium has good antibacterial property, can be used as antibacterial materials.

Optical and structural properties of undoped and Mn2+ doped Ca–Li hydroxyapatite nanopowders using mechanochemical synthesis

Undoped and Mn2+ doped calcium–lithium hydroxyapatite (CLHA) nanopowders were prepared by mechanochemical synthesis. The prepared samples were characterized by powder X-ray diffraction, scanning electron microscope, transmission electron microscope, optical absorption, photoluminescence, electron paramagnetic resonance and FT-IR spectroscopy techniques. From powder XRD pattern, lattice cell parameters and average crystallite sizes were evaluated. The morphologies of prepared samples were analyzed by using SEM and TEM studies. Optical and EPR data confirmed that the doped Mn2+ enter into the host material as distorted octahedral site. Photoluminescence spectra of undoped and Mn2+ doped CLHA nanopowders exhibited blue, blue-green emission bands at 425, 443, 468nm and green, strong orange emission bands at 534, 577nm respectively under the excitation wavelength of 365nm. The CIE chromaticity coordinates were also calculated from emission spectra for undoped and Mn2+ doped CLHA nanopowders. Vibrational bands related to phosphate molecules, P–O–H and hydroxyl ions are observed in FT-IR spectra.

Synthesis of rod-like hydroxyapatite with high surface area and pore volume from eggshells for effective adsorption of aqueous Pb(II)

We report the synthesis of rod-like hydroxyapatite nanopowder from waste eggshells (decomposed to CaO) and phosphoric acid at room temperature without pH control. The procedure involves the use of a syringe pump to control the addition rate of the phosphoric acid in order to maintain a stable pH. Results revealed that pure, rod-like, and nano-size hydroxyapatite particles were produced at various addition rates. Moreover, the sample obtained from 200ml/h addition rate exhibited large surface area (160.1m2/g) and pore volume (1.0cm3/g). Consequently, the prepared hydroxyapatite and that previously produced as adsorbents showed fast adsorption rates (10min) as well as very high maximum adsorption (qm=994.5mg/g and 1000.5mg/g, respectively) for Pb2+ in aqueous solution. Furthermore, the adsorption process revealed a pseudo-second-order reaction model and the equilibrium adsorption could be described by Langmuir model.

Crystalline size, microstructure and biocompatibility of hydroxyapatite nanopowders by hydrolysis of calcium hydrogen phosphate dehydrate (DCPD)

The crystalline size, microstructure and biocompatibility of hydroxyapatite (HA) bioceramic nanopowders synthesized by the hydrolysis of calcium hydrogen phosphate dehydrate (DCPD) at 75°C for 1h have been investigated. The crystallite size of HA nanopowders decreased from 23.1 to 13.7nm when the concentrations of additional alcohol increased from 0 to 70%, whereas an increase from 13.7 to 14.9nm was seen when the concentrations of additional alcohol increased from 70 to 90%. The morphology of HA nanopowders synthesized in a 2.5M NaOH solution with 1.9×10−3M CTAB and 70% alcohol was an almost spherical shape with a diameter of about 10.00nm. The variation trends of cell viability inversely corresponded to the crystallite size and morphology of HA nanopowders.

Processing and mechanical behavior of lamellar structured degradable magnesium–hydroxyapatite implants

Multilayered (laminated) composites exhibit tunable mechanical behavior compared to bulk materials due to the presence of more interfaces and therefore magnesium based composites are gaining wide popularity as biodegradable materials targeted for temporary implant applications. The objective of the present work is to fabricate magnesium based lamellar metal matrix composites (MMCs) for degradable implant applications. Nano-hydroxyapatite (HA) powder was selected as the secondary phase and lamellar structured magnesium-nano-hydroxyapatite (Mg–HA) composites of 8, 10 and 15wt% HA were fabricated by ball milling and spark plasma sintering. It was found that HA particles were coated on the Mg flakes after 20h of ball milling carried out using tungsten carbide (WC) as the milling media. Spark plasma sintering of the milled powders resulted in the formation of lamellar structure of Mg with the presence of HA and magnesium oxide (MgO) at the inter-lamellar sites of the composites. Phase analysis of the milled powder by an X-ray diffraction (XRD) method confirms the presence of HA and MgO along with Mg after sintering. Corrosion behavior of the composites investigated by potentiodynamic polarization tests shows a reduction in the inter-lamellar corrosion with increase in HA content and the best corrosion resistance is found for the Mg–10% HA composite. This composite also exhibits maximum Vickers hardness. Young׳s modulus and fracture toughness measured by nano-indentation method were higher for the Mg–8% HA composite. The results thus suggest that lamellar structured Mg composites with 8% and 10% HA show promise for temporary degradable orthopedic implant applications because of their improved corrosion resistance and superior mechanical properties.

Retraction

This article refers to:RETRACTED: Sol–gel preparation, characterisation and in vitro bioactivity of Mg containing bioactive glassRETRACTED: Effect of fluorine ion addition on structural, thermal, mechanical, solubility and biocompatibility characteristics of hydroxyapatite nanopowders