Hydroxyapatite Nanopowders Research Articles

Nanoemulsion synthesis of carbonated hydroxyapatite nanopowders: Effect of variant CO32−/PO43− molar ratios on phase, morphology, and bioactivity

Bone is a composite material containing carbonated hydroxyapatite (CHA) nanocrystallite and protein matrix. Low-temperature synthesis and assessment of the in vitro response of CHA nanopowders were conducted. Samples of CHA nanopowders were considered for their phase system, chemical compound, and reactions in a simulated body fluid (SBF). The crystallite size and phase for the CO32−/PO43− molar ratios of 0.67 and 1.00 were examined through X-ray diffraction (XRD). Chemical distinctiveness was analyzed by Fourier transform infrared (FTIR) spectroscopy. The compositions of the as-synthesized powders were quantified by X-ray fluorescence, and the carbon contents were estimated by carbon hydrogen nitrogen analysis. The morphology and textural properties were examined by field-emission scanning electron microscopy, transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. In vitro study was conducted in SBF medium, and the pH was intermittently recorded. Then, the dissolution of Ca2+ and PO43− in SBF was quantified by inductively coupled plasma optical emission spectroscopy. The outcomes of XRD and FTIR confirmed that pure single-phase B-type CHA without any secondary phase was formed. CHA.67 showed a crystallite size of (Scherrer) 22.7 nm, particle size by TEM (PTEM) of 24.87, and BET (PSBET) of 26.48 nm. Meanwhile, CHA1.00 achieved a crystallite and particle size of (Scherrer) 4.67, PTEM of 6.50, and PSBET of 13.23 nm. Results indicated that increasing the CO32−/PO43− molar ratio decreases the crystallite size and increases the amount of CO32−. Thus, we concluded that the nanoemulsion-synthesized CHA exhibits a crystallite size and chemistry comparable to those of biological hard tissue.

Influence of hydroxyapatite nanoparticles on the properties of glass ionomer cement

Glass ionomer cement (GIC) is an important restorative dental biomaterial which is utilized in filling, lining and adhesion restoration. The aim of this work is the enhancement of the mechanical, morphological, antibacterial and fluoride release properties of the glass ionomer cement by incorporation of different wt% of nano hydroxyapatite powder (HA). The result of this work refers to that, the addition of nano-HA to GIC enhance its fluoride ion release, compressive strength and antibacterial effect against Streptococcus mutans and the bacterial inhibition zone reached to about 8.6mm when 8% HA wt% is used. This suggests that addition of nano-HA particles to GIC to produce GIC-HA hybrids which can be used as suitable materials for improving its fluoride ion release, mechanical properties and inhibiting residual bacteria in dentine.

The Effects of Ageing Time on the Preparation of Nano-Hydroxyapatite by Chemical Precipitation Method

Nano-hydroxyapatite(nHAp) powders were prepared by chemical precipitation method using Ca(NO3)2·4H2O and (NH4)2HPO4 as raw materials and deionized water as solvent. To investigate the influence of ageing time on the preparation of nano HAp powder by changing the ageing time. And the composition and appearance of the samples were analyzed by infrared spectroscopy (FTIR), X ray diffraction (XRD) and scanning electron microscopy (SEM). With the longer ageing time, the samples gradually became sphere-like crystals and the crystallization degree were better.

Studies on adsorption of oxytetracycline from aqueous solutions onto hydroxyapatite

The presence of antibiotics in the water and wastewater has raised problems due to potential impacts on the environment and consequently their removal is of great importance. For this reason, this article aims to perform a study on the possibility of oxytetracycline (OTC) adsorption from aqueous medium by using the hydroxyapatite (HA) nanopowders as adsorbent materials. The hydroxyapatite nanopowders were synthesized by wet precipitation method by using orthophosphoric acid and calcium hydroxide as raw materials and investigated by XRD, SEM-EDX, FTIR and BET methods. The uncalcined and calcined hydroxyapatite samples have hexagonal crystal structure with crystal sizes smaller than 100nm and a specific surface area of 316m2/g and 139m2/g, respectively. The adsorption behavior of oxytetracycline, a zwitterionic antibiotic, on nanohydroxyapatite was investigated as a function of pH, contact time, adsorbent dosage and drug concentration by means of batch adsorption experiments. High oxytetracycline removal rates of about 97.58% and 89.95% for the uncalcined and calcined nanohydroxyapatites, respectively, were obtained at pH8 and ambient temperature. The adsorption process of oxytetracycline onto nanohydroxyapatite samples was found to follow a pseudo-second order and intraparticle diffusion kinetic models. The maximum adsorption capacities of 291.32mg/g and 278.27mg/g for uncalcined and calcined nanohydroxyapatite samples, respectively, have been found. The adsorption mechanism of OTC on the hydroxyapatite surface at pH8 can be established via surface complexation. The obtained results are indicative of good hydroxyapatite adsorption ability towards oxytetracycline drug.

Optimization of Pb(II) ions adsorption on nanohydroxyapatite adsorbents by applying Taguchi method

This paper presents an optimization approach for the removal of lead ions (Pb+2) by nano-hydroxyapatite powder form adsorbents that were produced from bovine bone by mechanical activation method. The Taguchi method was implemented for designing the experiments by considering four controllable factors including (1) ball milling time (A), (2) the initial concentration of lead ions (B), (3) initial pH of the solution (C); and (4) the adsorbent dosage (D), each factor at four different levels. According to the ANOVA analysis results, the removal efficiency of the lead ions was predominantly influenced by the adsorbent dosage (38.2%) and the initial lead ions concentration (23.64%), whereas the effect of initial pH of the solution was ignorable and the ball milling time had a mild contribution of 14.79%. The total optimum adsorptive lead ions removal of 100% was achieved by optimization process at operating conditions of Co = 180 mg L− 1, ball milling time = 2 h, pH = 3, and adsorbent dosage = 0.15 g. The Langmuir isotherm model fitted to the equilibrium results with good accuracy and a maximum sorption capacity of 200 mg g−1 was predicted by the model for the hydroxyapatite adsorbent ball milled for 2 h.

Development of hydroxyapatite/polyvinyl alcohol bionanocomposite for prosthesis implants

Hydroxyapatite (Ca10(PO4)6(OH)2) has similar structural and chemical properties of natural bone mineral and hence widely used as a bone replacement substitute. Natural bone consists of hydroxyapatite and collagen. For mimicking the natural, in the present work, a sintered porous hydroxyapatite component has been vacuum impregnated with Polyvinyl alcohol (PVA), which has better properties like biocompatibility, biodegradability and water- solubility. Hydroxyapatite powders have been made into nanosize to reduce the melting point and hence the sintering temperature. In the present investigation high energy ball mill is used to produce nano-hydroxyapatite powders in bulk quantity by optimizing the milling parameters using stainless steel grinding media. Pellets of 10 mm diameter have been produced from nano- hydroxyapatite powders under different uniaxial compaction pressures. The pellets have been sintered to form porous compacts. The vacuum impregnation of sintered pallets with PVA solution of different strength has been done to find the optimum impregnation condition. Microhardness, compressive strength, wear loss and haemocompatibility of hydroxyapatite ceramics have been studied before and after impregnation of PVA. The nano- hydroxyapatite/PVA composites have superior mechanical properties and reduced wear loss than the non-impregnated porous nano-hydroxyapatite ceramics.

Effect of concentration on nano hydroxyapatite powder by wet chemical precipitation route

Effect of concentration on nano hydroxyapatite powder by wet chemical precipitation route

Synthesis and Characterisation of Poly (Glycerol-co-Citrate)/ n-HAp Composite for Biomedical Applications

Citric acid based polyester has found widespread application in biomedical engineering such as tissue engineering, drug delivery and bio-imaging. The incorporation of nanohydroxyapatite in polymeric structure enhances the biocompatibility. The polyester, poly (Glycerol-Co-Citrate) was synthesised by catalyst free melt polycondensation. Nanohydroxyapatite powder was synthesised by sol gel method using calcium nitrate and phosphoric acid as calcium and phosphorus precursors respectively. The polyester n-HAp composite was prepared by solution mixing. The synthesised polyester and polymer nanocomposites were characterised by solubility studies, FTIR, 1HNMR and 13CNMR. The thermal stability of polymer nanocomposites was studied by Differential Scanning Colorimetry. The morphology of the polymer nanocomposite thin film was studied by SEM. The glass transition temperature of both the polymer and its composite are below room temperature which shows the elastomeric nature of these materials. Thus, the prepared polymer and its composite can be used as biomaterials.

Implant application of bioactive nano-hydroxyapatite powders—a comparative study

Hydroxyapatite (HAp) is commonly used as a bone-substitute material because of its bioactive and biocompatible properties. The aim of the present study is to compare the two different types of nano-HAps powders, to ascertain their properties in a biological environment. The nano-HAps powders were synthesized in two ways (i) chemical method by co-precipitation (cHAp) (ii) natural method by calcination of goat femur bone (nHAp). The cHAp and nHAp powders were analyzed by x-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis to find out the crystallinity, morphology, particle size and phase changes of the samples respectively. High crystallinity and controlled morphology were observed in nHAp compared to cHAp. In-vitro studies such as biodegradation, protein adsorption and hemolysis were carried out to determine the biocompatibility nature of these nanoparticles. It was found that, both cHAp and nHAp nano powders are active in the biological environment. On comparison, nHAp nanoparticles showed better performance than cHAp.

Nano-hydroxyapatite formation by using ultrasonic

Hydroxyapatite nanoparticles were synthesized, using a wet chemical technique from diammonium hydrogen phosphate and calcium nitrate tetrahydrate precursors, Ammonia used in control of the acidic function at 11. The use of ultrasound to study the impact on the particle sizes. The prepared powder was used for further characterization. The prepared Nano-hydroxyapatite powder was characterized for phase composition, using X-ray diffraction elemental dispersive X-ray and Fourier transform infrared spectroscopy. The elemental compositions of the Nano-hydroxyapatite were analyzed. The particle size and morphology were studied using the scanning electron microscope (SEM), The scanning electron microscope are among the particles are bacilli, where he was treated article ultrasound waves 50 watt gave sizes up to 30 nm, and when it was treated card 40 watts gave sizes up to 50 nm.

Nano Ag/ZnO-Incorporated Hydroxyapatite Composite Coatings: Highly Effective Infection Prevention and Excellent Osteointegration.

Interfacial characteristics play an important role in infection prevention and osteointegration of artificial bone implants. In this work, both Ag nanoparticles (AgNPs) and ZnO NPs are incorporated into hydroxyapatite (HA) nanopowders and deposited onto Ti6Al4V (Ti6) implants by laser cladding. The composite coatings possess a hierarchical surface structure with homogeneous distributions of Ag and ZnO. The Ag and ZnO NPs that are immobilized by laser cladding ensure long-term and gradual release of Ag and Zn ions at low cumulative concentrations of 36.2 and 56.4 μg/L after immersion for 21 days. A large concentration of Ag released initially increases the cytotoxicity but the large initial ZnO content enhances the cell viability and osteogenetic ability. The nano Ag/ZnO-embedded HA coating (Ag/ZnO/HA = 7:3:90 wt %, namely Ag7ZnO3HA) exhibits optimal antibacterial efficacy and osteogenetic capability, as exemplified by the broad spectrum antibacterial efficacy of 96.5 and 85.8% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively, together with enhanced osteoinductivity with higher alkaline phosphatase (ALP) activity of 134.60 U/g protein compared to 70.79 U/g protein for the untreated implants after culturing for 7 days. The rabbit femoral implant model further confirms that the optimized composite coating accelerates the formation of new bone tissues indicating 87.15% of the newly formed bone area and osteointegration showing 83.75% of the bone-implant contact area even in the presence of injected S. aureus. The laser-cladded Ag7ZnO3HA composite coatings are promising metallic implants with excellent intrinsic antibacterial activity and osteointegration ability.

Synthesis and Characterisation of Hydroxyapatite Nanopowders by Hydrothermal Method

In this study, a hydrothermal method of synthesizing Hydroxyapatite (HAp) by heating a precipitate, formed by mixing Ca (NO3) 2. 4 H2O and (NH4) 2 HPO4 with distilled water, in hydrothermal reaction 200 0C for 24 hrs has been described. After that, the characterisation techniques were used such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Selected Area of Electron Diffraction (SAED) and Energy-Dispersive X-ray spectroscopy (EDX). Results indicated that the pure (HAp) nanostructure with uniform morphologies, controllable size, nano-dispersion and narrow-size distribution in diameter were synthesized successfully, and the synthesized powders can be used extensively in medicine, dentistry for implant synthesis and for scientific research

Wet chemistry approach to the preparation of tantalum-doped hydroxyapatite: Dopant content effects

Tantalum-doped hydroxyapatite (Ta-doped HA) nanopowders with different Ta contents were synthesized by a wet-chemical precipitation route. The structure modification and charge compensation mechanism were investigated by various characterization techniques. Due to the smaller size of tantalum ions compared to the Ca2+ size, it was assumed that the tantalum ions occupy either the Ca2+ and/or the interstitial positions in the HA lattice, where the charge imbalance from to this substitution was compensated by the Ca2+ vacancies. From the XRD patterns, the as-synthesized nanopowders were poorly crystalline apatite in the absence and presence of different dopant contents. The hexagonal HA and tricalcium phosphate (β-TCP) phases as biphasic calcium phosphate mixtures were formed after heating at 900°C. In addition to the β-TCP phase, minor extra phases such as calcium oxide (CaO) and calcium pyrophosphate (Ca2P2O7) were identified from the HA decomposition. The FTIR results indicated that the decrease of structural hydroxyl groups depended on both tantalum oxyanions and carbonate contents. In the XPS profile, the Ta 4f peak of the doped sample could be decomposed into four main components, which showed different oxidation states for tantalum (TaO2 oxide). According to the TEM observations, the doped calcined powder at 900°C was composed of uniform nanoneedles with an average length and width of 120 ± 50 and 10 ± 5nm, respectively.

Biodegradability and antibacterial properties of MAO coatings formed on Mg-Sr-Ca alloys in an electrolyte containing Ag doped hydroxyapatite

Magnesium-based alloys are promising materials as next generation biodegradable implants, however low corrosion resistance and inadequate mechanical properties are limiting their application as a biodegradable implant material. In this study, Mg-Sr-Ca ternary alloys were prepared in a vacuum/atmosphere controlled furnace and coated by microarc oxidation (MAO) process for 5min to decrease the degradation rate and enhance the biocompatibility. Moreover, Ag doped Hydroxyapatite nano powder (Ag-HA) was also added to alkaline MAO solution by amount of 1 and 10g/l to improve the antibacterial properties while enhancing their bioactivity in a one single process. XRD, SEM-EDS, FTIR spectroscopy, simulated body fluid (SBF) immersion and antibacterial tests were employed for the characterization of the coated alloys. The results showed that, the addition of more Ag-HA increased the HA formation both before and after SBF immersion test and enhanced their antibacterial properties. However, Ag-HA addition decreased the corrosion resistance of the coated alloys in SBF compared to Ag-HA free coating. The results indicated that the present Ag-HA nano powder added MAO coating is a good combination to enhance the corrosion resistance, bioactivity and the antibacterial properties of Mg based biodegradable alloys.

Influence of microwave power and irradiation time on some properties of hydroxyapatite nanopowders

Microwave (MW) assisted synthesis of hydroxyapatite (HAP) nanopowders (NPs) is an efficient and eco-friendly contemporary technique. This paper discusses the influence of two MW parameters i.e., microwave power (MWP) and irradiation time (MWIT) on structural and physicochemical properties of HAP NPs. MWP and MWIT settings had little effect on phase constitution of NPs as suggested by XRD analysis. HAP was a major phase in all NPs. Rietveld refinement suggested that with the increase in MWP and changes in MWIT settings, bond length, and Ca/P molar ratio increased, whereas, crystal size, crystallinity, and microstrain of NPs decreased. Also, HAP unit cell contracted along a-axis and expanded along c-axis with the increase in MWP and changes in MWIT settings. FTIR corroborated XRD phase analysis and suggested bone-like apatitic formation in all NPs. FESEM indicated agglomerated state of NPs constituted of nano-dimensional elongated particles. TEM suggested the rod shaped particles having aspect ratio varied between 2 and 3. EDX results corroborated with XRD and FTIR results. By analysis of all results, properties of NPs irradiated at 900 and 1200 W were relatively more promising. Hence, this study systematically and minutely examined the overall effect of MW parameters on various properties of HAP NPs.

In vitro performance of silver-doped hydroxyapatite nanopowders—a micro study

Silver-doped hydroxyapatite (AgHAP) nanopowders (NPs) have been receiving immense attention in orthopedic and dental implant applications owing to high bioactivity and antimicrobial properties. This study comprehensively investigated the influence of in vitro immersion durations of 7 and 30 days on structural and physico-chemical properties of AgHAP NPs. XRD revealed that different immersion durations formed different secondary phases. Rietveld refinement suggested that with the increase in duration of immersion, inter-atomic distance between atoms and crystallinity of NPs decreased, whereas distortion of lattice parameters, crystal size, and micro-strain of NPs increased. FTIR supported XRD phase analysis and confirmed the formation of apatite in all NPs. NPs that were agglomerated consisted of particles of irregular shapes and sizes as revealed by SEM. EDX corroborated with XRD phase analysis and detected all desirable elements constituting HAP phase. Disparity between hydrodynamic diameter (DLS testing) and crystal sizes determined using Scherrer formula and Rietveld refinement was observed. In vitro pH measurement of SBF suggested the bioactive nature of NPs and also revealed the higher rate of solubility of AgHAP NPs. AgHAP NPs gained weight after 30 days of immersion in SBF.

Polyelectrolyte multi-layers assembly of SiCHA nanopowders and collagen type I on aminolysed PLA films to enhance cell-material interactions

This paper presents a new approach in assembling bone extracellular matrix components onto PLA films, and investigates the most favourable environment which can be created using the technique for cell-material interactions. Poly (lactic acid) (PLA) films were chemically modified by covalently binding the poly(ethylene imine) (PEI) as to prepare the substrate for immobilization of polyelectrolyte multilayers (PEMs) coating. Negatively charged polyelectrolyte consists of well-dispersed silicon-carbonated hydroxyapatite (SiCHA) nanopowders in hyaluronic acid (Hya) was deposited onto the modified PLA films followed by SiCHA in collagen type I as the positively charged polyelectrolyte. The outermost layer was finally cross-linked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrocholoride and N-hydroxysulfosuccinimide sodium salt (EDC/NHS) solutions. The physicochemical features of the coated PLA films were monitored via X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscope (AFM). The amounts of calcium and collagen deposited on the surface were qualitatively and quantitatively determined. The surface characterizations suggested that 5-BL has the optimum surface roughness and highest amounts of calcium and collagen depositions among tested films. In vitro human mesenchymal stem cells (hMSCs) cultured on the coated PLA films confirmed that the coating materials greatly improved cell attachment and survival compared to unmodified PLA films. The cell viability, cell proliferation and Alkaline Phosphatase (ALP) expression on 5-BL were found to be the most favourable of the tested films. Hence, this newly developed coating materials assembly could contribute to the improvement of the bioactivity of polymeric materials and structures aimed to bone tissue engineering applications.

Case study: Reinforcement of 45S5 bioglass robocast scaffolds by HA/PCL nanocomposite coatings.

The purpose of this study is to analyze the mechanical enhancement provided by nanocomposite coatings deposited on robocast 45S5 bioglass (BG) scaffolds for bone tissue regeneration. In particular, a nanocomposite layer consisting of hydroxyapatite (HA) nanoparticles, as reinforcing phase, in a polycaprolactone (PCL) matrix was deposited onto the surface of the BG struts conforming the scaffold. Three different HA nanopowders were used in this study. The effect of particle size and morphology of these HA nanopowders on the mechanical performance of 45S5 BG scaffolds is evaluated.

Compaction of hydroxyapatite nanopowders by hydrostatic pressing

In this work, we show how the degree of compaction upon pressing of two hydroxyapatite nanopowders, whose average particle sizes are 18 and 65 nm, influences the density and strength of ceramics on their basis. The density and the flexural strength are found to be higher for a ceramic based on the powder with the particle size of 65 nm at the same density of precursors. The flexural strength of ceramic on its base was 20–25% higher than for ceramic of a powder with the average particle size of 18 nm at the identical density of precursors. The additional hydrostatic pressing increases the densities of specimens by 10–12%. The final hydroxyapatite ceramics are characterized by a fairly high bending density of 170 MPa and homogeneous structure with the average crystallite size of 0.4–0.6 μm.

An ANFIS model to prediction of corrosion resistance of coated implant materials

In the present study, an adaptive neuro-fuzzy inference system (ANFIS) model has been used for predicting the corrosion resistance of AA6061-T4 alloy coated with micro-/nano-hydroxyapatite (HA) powders by sol–gel technique. The input parameters of the model consist of the HA powder size (micro-/nanoscale, 35 μm/20 nm), coating thickness (30, 60 and 85 μm) and potential values, while the output parameter is corrosion current density. The performance of proposed ANFIS model was tested on the potentiodynamic polarization scanning (PDS) curves by comparing experimental and the theoretical results of the coatings. The results showed that the generated PDS curves of the coatings are in definitely acceptable levels with obtained results in our experimental reference study. Then, the combined effect of arbitrary selected coating thickness and HA powder size on corrosion behaviour of the coatings was also predicted by trained ANFIS model without using any experimental data. And finally, the predicted results for the arbitrary selected coating thicknesses were compared by validation tests. The results showed that the ANFIS has potential to be used in industrial applications of biomedical implant materials coated with HA without performing any experiments after detailed systematic studies in the near future.