HAp Particles Research Articles

Pt/facet-Engineered Hydroxyapatite Co-Catalyst for Highly Efficient Hydrolysis of Ammonia Borane

Ammonia borane (AB, NH3BH3) is a promising candidate for a hydrogen-storage material because of its high stability as a solid state at room temperature under atmospheric pressure. This study demonstrated a novel catalyst design for highly efficient hydrolysis of AB by hybridizing Pt catalyst with hydroxyapatite (HAp, Ca10(PO4)6(OH)2) as an “active support”, possessing Lewis-acidic Ca2+ sites in the a-plane and Lewis-basic PO43- sites in the c-plane. Facet-engineered HAp particles were synthesized via the microwave-assisted hydrothermal reaction using Ca-EDTA chelates. Varying the Ca/P ratio of HAp precursor (from 1.5 to 1.8) affected the particle morphology, exposed facet ratio of {300} to {002}, and the percentage of phosphate anion species (PO43- and HPO42-). The rod-like HAp sole catalysts performed approximately 2-fold higher activity for the hydrolysis of AB, compared with spherical HAp with low crystallinity. Moreover, the Pt/rod-like HAp co-catalyst demonstrated superior catalytic performance with a turnover frequency (TOF) of 623 molH2 molPt-1 min-1 than the Pt/spherical HAp (<232 molH2 molPt-1 min-1). We proposed a possible mechanism of a synergistic effect in the significant enhancement of the hydrogen release rate from AB. Lewis basic PO43- and Lewis acidic Ca2+ sites on HAp would affect preferential adsorption of electron-deficient BH3 and electron-rich NH3 groups in AB, catalyzing cleavage of B-N bonds. Besides, PO43- sites play a critical role in anchoring Pt particles towards electron transfer from Pt to PO43-, resulting in considerable enhancement of catalytic performance in dissociative adsorption of water molecules, which is a rate-determining step in the hydrolysis.Graphical

Comparative study between chemical precipitation and chemical precipitation by spraying for the recovery of nanometric hydroxyapatite

The aim of this work was to develop a new method of assisted precipitation by spraying to obtain nanometer-sized hydroxyapatite and to compare it with conventional chemical precipitation by droplets. Scanning electron microscopy showed the morphological characteristics flake-like of HAp particles synthesized by the spray method at different reaction times and the formation of HAp from the first reaction time, which is different from the droplet method. X-ray diffraction confirmed the crystal structure and size of the synthesized HAp by Rietveld refinement, showing a crystallite size of about 3.77 nm for the spray synthesis and 18 nm for the droplet synthesis. FTIR and Raman were used to analyze the active normal vibrational modes of the synthesized HAp. The results showed that in the spray system, HAp formation occurs at the beginning of the reaction, a phenomenon that was not observed in the droplet method. In particular, FTIR analysis showed the presence of phosphate and carbonate modes of HAp as early as 9 minutes, which persisted throughout the reaction. This Furthermore, dynamic light scattering measurements show that the size distribution of HAp particles synthesized using the novel spray system is between 2 and 5 μm. This shows that the distribution with the spray method is more stable than with the droplet method, which shows the presence of irregular particles with a size distribution at 3 μm. The results emphasize the effectiveness of the proposed method in producing HAp with desirable properties for various biomedical applications.

Fabrication and properties of hydroxyapatite/chitosan composite scaffolds loaded with periostin for bone regeneration

This paper reports a facile fabrication method of hydroxyapatite/chitosan (HAp/CS) composite scaffold with 3D porous structure without using any chemical cross-linkers. The HAp particles had an urchin-like hollow microstructure and high surface area, which was uniformly dispersed into the pore walls of the HAp/CS scaffold. The addition of HAp can efficiently enhance the mechanical properties and bioactivity of the HAp/CS scaffold. Moreover, periostin was successfully loaded onto the HAp/CS scaffold. When applied to the repair of bone defect in a rat mandibular model, the HAp/CS scaffold loaded with periostin can enhance osteointegration and accelerate bone regeneration. Our research combines periostin with the HAp/CS composite material, which provides a novel strategy to improve bone regeneration and has great application prospect in bone repair fields.

Remineralization Induced by Biomimetic Hydroxyapatite Toothpastes on Human Enamel.

This work aimed to compare the effect of four new toothpastes (P1-P4) based on pure and biomimetic substituted nano-hydroxyapatites (HAPs) on remineralization of human enamel. Artificially demineralized enamel slices were daily treated for ten days with different toothpastes according to the experimental design. Tooth enamel surfaces were investigated using atomic force microscope (AFM) images and surface roughness (Ra) determined before and after treatment. The surface roughness of enamel slices was statistically analyzed by one-way ANOVA and Bonferroni's multiple comparison test. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data revealed the HAP structure with crystal sizes between 28 and 33 nm and crystallinity between 29 and 37%. The average size of HAP particles was found to be between 30 and 40 nm. The Ra values indicated that P3 (HAP-Mg-Zn-Sr-Si) toothpaste was the most effective after 10 days of treatment, leading to the lowest mean roughness. The P3 and P2 (HAP) toothpastes were found to be effective in promoting remineralization. Specifically, their effectiveness can be ranked as follows: P3 = P2 > P4 (HAP-Mg-Zn-Si) > P1 (HAP-Zn), considering both the chemical composition and the size of their constitutive nanoparticles. The proposed toothpastes might be used successfully to treat early tooth decay.

Electrochemical deposition of a biofunctionalised silver and strontium substituted hydroxyapatite nanocomposite coating on a β-type titanium alloy

ABSTRACT As a result of hydroxyapatite’s (HAp) similarity to the mineral component of bone, it has been extensively investigated for biomedical application. To mimic the non-stoichiometric hydroxyapatite of bone or add positive features to it, different cationic and anionic substitutions have been studied. In this study, the nanocomposite coating of strontium (Sr) and silver (Ag) substituted HAp was deposited on a rarely investigated β type titanium alloy with low Young’s modulus to investigate its morphological and chemical features, crystallographic structure, thickness, biocompatibility, and hydrophilicity. The coating was deposited via a little reported electrochemical method which has the advantages of both electrolytic and electrophoretic deposition. The process is simple and can be conducted under mild experimental conditions to prevent potential high-temperature induced-thermal stress complications. The chemical, morphological and crystallographic features were characterised using EDAX, FE-SEM, and XRD analysis. The coating thickness was measured using a profilometry test. The biocompatibility and wetting behaviour were evaluated by MTT assay and the sessile drop technique, respectively. The coatings have shown rod-shaped, homogenous, and nano-sized HAp particles, with a close Ca/P ratio to stoichiometric apatite; meanwhile, Sr and Ag nanosphere particles are capable of modifying its surface. The coating can support cell growth and proliferation and shows a superhydrophilic surface.

An Evaluation of the Mechanical Properties of a Hybrid Composite Containing Hydroxyapatite.

There is currently a lack of scientific reports on the use of composites based on UDMA resin containing HAp in conservative dentistry. The aim of this study was therefore to determine the effect of hydroxyapatite content on the properties of a hybrid composite used in conservative dentistry. This paper compares a commercial hybrid composite with experimental composites treated with 2% by weight (b/w), 5% b/w, and 8% b/w hydroxyapatite. The composites were subjected to bending strength, compression, and diametrical compression tests, as well as those for impact strength, hardness, and tribological wear. The obtained results were subjected to statistical analysis. Increased hydroxyapatite was found to weaken the mechanical properties; however, 2% b/w and 5% b/w hydroxyapatite powder was found to achieve acceptable results. The statistical analysis showed no significant differences. HAp is an effective treatment for composites when applied at a low concentration. Further research is needed to identify an appropriate size of HAp particles that can be introduced into a composite to adequately activate the surface and modification its composition.

Improving interface interactions in PLA/HAP composites with hydroxyapatite surface modification

ABSTRACT PLA/HAP composites have attracted significant attention in material science, especially in the field of biomaterials. However, these composites have suffered from unfavorable interface interactions between PLA and HAP interfaces, which limits the applications . In this study, we aimed to improve the interface interactions of PLA/HAP composite by modifying the HAP surface. For this purpose, HAP particles were functionalized with three different silane modifying agents, including (3-Aminopropyl)trimethoxysilane (AMMO), (3-glycidyloxypropyl)trimethoxysilane (GLYMO) and (3-triethoxysilyl)propylsuccinic anhydride (GF-20). The obtained modified HAP (m-HAP) were used to prepare PLA/m-HAP. Interface interactions of composites were characterized by Fourier transform infrared spectrophotometer (FT-IR) and differential scanning calorimetry (DSC). In addition, Vickers hardness tests were performed to reveal the effect of silane modifying agents on hardness before and after the in vitro degradation test.

Synthesis and characterization of Mg-hydroxyapatite and its cellulose hybridized structure as enhanced bio-carrier of oxaliplatin drug; equilibrium and release kinetics.

An advanced form of magnesium-doped hydroxyapatite (Mg HAP) was synthesized and hybridized with cellulose fibers, producing a safe biocomposite (CF/Mg HAP) as an enhanced delivery structure of traditional oxaliplatin (OXPN) chemotherapy drug during the treatment stages of colorectal cancer. The qualifications of CF/Mg HAP as a carrier for OXPN were followed based on loading, release, and cytotoxicity as compared to Mg HAP. The CF/Mg HAP composite exhibits a notably higher OXPN encapsulation capacity (256.2 mg g-1) than the Mg HAP phase (148.9 mg g-1). The OXPN encapsulation process into CF/Mg HAP displays the isotherm behavior of the Langmuir model (R2 = 0.99) and the kinetic assumptions of pseudo-first-order kinetics (R2 > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the cellulose hybridization steps (Nm = 178.58 mg g-1) as compared to pure Mg HAP (Nm = 69.39 mg g-1). Also, the capacity of each site was enhanced to be loaded by 2 OXPN molecules (n = 1.43) in a vertical orientation. The OXPN encapsulation energy into CF/Mg HAP (<40 kJ mol-1) reflects physical encapsulation reactions involving van der Waals forces and hydrogen bonding. The OXPN release profiles of CF/Mg HAP exhibit slow and controlled properties for about 100 h, either at pH 5.5 or pH 7.4. The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and a complex erosion/diffusion release mechanism. The free CF/Mg HAP particles display a considerable cytotoxic effect on the HCT-116 cancer cells (21.82% cell viability), and their OXPN-loaded product shows a strong cytotoxic effect (1.85% cell viability).

The Influence of Nanosilica on Properties of Cement Based on Tetracalcium Phosphate/Monetite Mixture with Addition of Magnesium Pyrophoshate.

The effect of nanosilica on the microstructure setting process of tetracalcium phosphate/nanomonetite calcium phosphate cement mixture (CPC) with the addition of 5 wt% of magnesium pyrophosphate (assigned as CT5MP) and osteogenic differentiation of mesenchymal stem cells cultured in cement extracts were studied. A more compact microstructure was observed in CT5MP cement with 0.5 wt% addition of nanosilica (CT5MP1Si) due to the synergistic effect of Mg2P2O7 particles, which strengthened the cement matrix and nanosilica, which supported gradual growth and recrystallization of HAP particles to form compact agglomerates. The addition of 0.5 wt% of nanosilica to CT5MP cement caused an increase in CS from 18 to 24 MPa while the setting time increased almost twofold. It was verified that adding nanosilica to CPC cement, even in a low amount (0.5 and 1 wt% of nanosilica), positively affected the injectability of cement pastes and differentiation of cells with upregulation of osteogenic markers in cells cultured in cement extracts. Results revealed appropriate properties of these types of cement for filling bone defects.

The potential of eggshell hydroxyapatite, collagen, and EGCG (HAp-Col-EGCG) scaffold as a pulp regeneration material

BackgroundHydrogel scaffold is a biomaterial that can facilitate cells in forming a tissue structure. It can promote cell adhesion, migration, and proliferation. Further research to find a new scaffold from natural resources is challenging, so this study aimed to characterize a hydrogel composite scaffold, which has the potential to be used as a regenerative material. MethodsThe formulation of HAp-Col-EGCG was mixed with different ratios of 1%, 2%, and 4% hydroxyapatite. We analyzed its injectability, pH, and gelation time. Scanning electron microscopy (SEM), energy X-ray Spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR) were used to evaluate the surface morphologies, element composition, and chemical properties of HAp-Col-EGCG. ResultsThe results showed that the injectability test was almost 90 % in all groups. There was no significant difference in the median value of the pH at 0, 20, and 60 min in all groups, but there was a significant difference at 40 min. The average gelation times in all groups were not significant. SEM-EDX showed a microporous scaffold, with the HAp particles well distributed in the collagen pores at a ratio of 1.9, 2.29, and 1.89 Ca/P. The FTIR results showed intermolecular bonds in the HAp-Col-EGCG scaffold. The X-ray diffraction analysis showed that collagen and EGCG did not affect the crystal structure and size of HAp. Cytotoxicity test showed more dental pulp cell viability at the 4 % HAp concentration at 514.35 ± 15.45. ConclusionThis study indicates that hydrogel scaffold from eggshell hydroxyapatite, collagen, and EGCG has a high potential for pulp regenerative therapy.

The distinctive role of nano-hydroxyapatite modified biochar for alleviation of cadmium and arsenic toxicity in aqueous system

The synergetic behavior of cadmium and arsenic in water is characterized by increased mobility and toxicity. The control of Cd and As toxicity is one of the greatest environmental challenges in the world. Biochar with a strong adsorption affinity for cations is considered to sequester Cd(II). However, little is known about whether biochar and its modified materials are efficient in the removal of cations and anions in a dual system. In this study, wheat straw and nanohydroxyapatite were used to prepare nanohydroxyapatite-modified biochar (HBC) and to control cationic Cd(II) and anionic As(III) in water. As the mass ratio of nHAP to wheat straw biochar was increased from 0.1 % to 1.0 %, the amount of nHAP particles loaded on the surface of BC increased, and the particles tended to aggregate. In the single and binary contaminant systems, the maximum Langmuir adsorption capacities of HBC for Cd(II) and As(III) were 55.95 and 14.84 and 14.24 and 12.44 mg/g, respectively. Cd and As adsorption by HBCs was influenced by physical adsorption, electrostatic interactions, hydroxyl groups, and surface complexation, accompanied by specific adsorption induced by HAP particles on HBCs. The findings of the current investigation showed that HBCs can be used as green and low-cost amendments, which would help in the treatment of wastewater contaminated by multiple heavy metals.

Different Methods for Preparation of Hydroxyapatite Nanostructures

Hydroxyapatite could be utilized as a bioceramic owing to its osteoconductivity and bioactivity characteristics. It is obvious that the shape of HAp nanoparticles clearly influences their properties such as bioactivity and surface area. Nano-sized HAp particles with different morphologies were synthesized using a variety of preparation processes such as solvothermal, microwave-solvothermal, precipitation and hydrothermal-precipitation process. The effect of preparation methods on particle morphology was studied. The X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Zeta potential (ZP), were used to validate the composition and structure of the as-formulated HAp nanostructures. A single phase of HAp was obtained using various methods of preparation. According to the TEM analysis of the powders, both the solvothermal and the hydrothermal treatment samples were very diffuse and consisted of fairly homogeneous HAp nanorods.

Hydroxyapatite as Remineralization Agent for Children's Dental Care

Children are prone to develop dental caries. This is supported by epidemiological data confirming early childhood caries (ECC) as a highly prevalent disease affecting more than every second child worldwide. ECC is known to result from an imbalance between re- and demineralization where demineralization dominates due to frequent acid production by cariogenic bacteria present in oral biofilms. The application of oral care formulations containing remineralizing agents helps to prevent dental caries. As young children are sensitive and usually swallow (intended or unintended) a majority of toothpaste or other oral care products during daily dental care, all ingredients, especially the actives, should be non-toxic. Biomimetic hydroxyapatite [HAP; Ca5(PO4)3(OH)] is known to have favorable remineralizing properties combined with an excellent biocompatibility, i.e., it is safe if accidently swallowed. Several clinical trials as well as in situ and in vitro studies have shown that HAP remineralizes enamel and dentin. Remineralization occurs due to deposition of HAP particles on tooth surfaces forming mineral-mineral bridges with enamel crystals, but also indirectly through calcium and phosphate ions release as well as HAP's buffering properties in acidic environments (i.e., in plaque). HAP induces a homogenous remineralization throughout the subsurface enamel lesions. This review summarizes the current evidence showing HAP as an effective remineralizing agent in oral care products for children. Additional studies showing also further beneficial effects of HAP such as the reduction of biofilm formation and the relief of hypersensitivity in children with molar incisor hypomineralization (MIH). It can be concluded that HAP is an effective and safe remineralizing agent for child dental care.

Study on surface properties of UHMWPE/Hap composite coating on Ti6Al4V

ABSTRACT In the present study, UHMWPE (Ultra High Molecular Weight Polyethylene)- 0.5, 1 and 2 wt-% Hap (hydroxyapatite) composite film coatings on Ti6Al4V alloy were produced by dip coating method. Homogeneous dispersion of Hap particles was detected by SEM (Scanning Electron Microscope) and FE-SEM (Field Emission Scanning Electron Microscope). The characteristic absorption peaks of Hap are observed by FTIR (Fourier Transform Infrared Spectroscopy). Hap addition caused the increment of the crystallinities of composites from 24.6% to 56.8% related with the increment of the melting temperatures. Composite coatings showed excellent wear resistance with the decreasing worn area of 96% and the friction coefficient of 97%, compared to the uncoated Ti6Al4V. The biocompatibility and wettability tests of all coated surfaces were performed. It is foreseen that UHMWPE/2wt-%Hap composite film coating on Ti6Al4V will be promising for Hip joint prosthesis.

Adhesion and whitening efficacy of P11-4 self-assembling peptide and HAP suspension after using NaOCl as a pre-treatment agent

BackgroundThis study evaluated the adhesion and whitening efficacy of a mixture of hydroxyapatite and P11-4 self-assembling peptide (HAP-peptide) on bovine enamel after pre-treatment with low-concentrated sodium hypochlorite (NaOCl).MethodsFifty-two caries-free bovine incisors were selected. 50 teeth were randomly allocated to five groups (n = 10). The first group was treated with a mixture of 6.25 wt% HAP and 5 ml P11-4 peptide, using NaOCl 3% as pre-treatment. Second, third and fourth groups were treated with 6.25 wt% HAP, 5 ml P11-4 peptide, and NaOCl 3%, respectively. In the fifth group, only water was applied (control group). The color of samples was measured using a spectrophotometer (USB4000-VIS-NIR-ES, Ostfildern, Germany). To evaluate color changes, ΔE values were statistically analyzed. Finally, adherence of HAP particles on two enamel surfaces with and without pre-treatment with NaOCl was analyzed with SEM.ResultsIt was observed that the ΔE of the HAP-peptide suspension after pre-treatment with NaOCl was significantly stronger than the control group. In contrast, the overall color changes of separate applications of HAP, peptide, and NaOCl did not differ notably from the control group. SEM observations confirmed that pre-treatment with NaOCl resulted in a more pronounced coverage of HAP on the enamel surface.ConclusionsPre-treatment with a low-concentrated NaOCl enhanced the adherence of the HAP layer on the enamel surface, resulting in a stronger whitening effect.Trial registrationThe peptide-HAP suspension is effective in improving tooth whiteness.

Defluoridation efficiency assessment of spiny hierarchical-structured calcium hydroxyphosphate particles

In present study, fine calcium hydroxyphosphate (Ca 5 (PO 4 ) 3 (OH), HAP) particles with spiny hierarchical-structured morphology were prepared through a unique phase-transformation process of solid CaSO 4 ·2H 2 O in a controlled double jet precipitation system. The obtained spiny hierarchical-structured-HAP powder was tested on its defluoridation efficiency by using the synthetic solution and real coal mine water samples respectively, and it was confirmed that the spiny nanowhiskers on the surface of the HAP played an indispensible role that made it much better than the commercial HAP particles. The adsorption kinetics and isotherm behavior were also investigated, and the maximum adsorption capacity for fluoride was evaluated as 12.2 mg/g at the neutral pH. All coexisting anions like sulfate, chloride, nitrate, phosphate and carbonate were found to cause about 10–20% decrease in the defluoridation efficiency only when their concentrations were 2–200 factors larger than that of fluoride, and it could be reused for at least 5 cycles of adsorption/elution without decreasing the adsorption efficiency drastically in a batch adsorption mode. The real coal mine water sampled from Ejin Horo Qi, Ordos city, Inner Mongolia, was used for the column adsorption test, and even after 3 cycles of adsorption/elution it still maintained high defluoridation efficiency. The present study provided a promising defluoridation method to remove the excessive fluoride from the real coal mine water efficiently by a cheap and effective way. • A facile novel process to prepare spiny hierarchical-structured HAP particles on large scale were proposed successfully. • Phase transformation of CaSO 4 ·2H 2 O to Ca 5 (PO 4 ) 3 OH is essential to the formation of spiny hierarchical-structure. • Spiny HAP particles had much better defluoridation capability than commercial HAP directly at neutral pH. • Nanowhiskers of HAP was observed by TEM on the surface of the obtained Ca 5 (PO 4 ) 3 OH. • Fluoride in the real coal mine water was efficiently removed by spiny HAP particles.

Incorporation of hydroxyapatite in crosslinked gelatin/chitosan/poly(vinyl alcohol) hybrids utilizing as reinforced composite sponges, and their water absorption ability

The crosslinked gelatin/chitosan/poly(vinyl alcohol)/hydroxyapatite (GEL/CTS/PVA/HAp, GCPH) sponges were fabricated by a freeze-drying method to yield the reinforced composite sponges with proper features. The porosity value and pore size of the crosslinked GCPH sponges reached ∼80% and 50–100 ​μm, respectively, which can be an appropriate range to allow cells to migrate into the reinforced composite sponges in the tissue engineering technology. Besides, the proper bonding presence between HAp particles and the crosslinked polymeric matrix or the crosslinked network formation between the polymers were also proved through fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal gravimetric (TG/DTG) analysis. Owing to incorporation of HAp particles and good distribution of HAp particles inside the crosslinked polymeric matrix, their mechanical properties were improved through the determination of compression tests. Concomitantly, their water absorption ability reached effectively in both the distilled water and NaCl solution, and their recovery also maintained well for 10 absorbing–squeezing cycles to be considered as an effective reusability for the crosslinked sponge system. Thereby, the crosslinked GCPH sponge prepared in the present study can become a potential candidate to apply especially in the biomedical/medical applications and tissue engineering technology.

On the synergistic corrosion inhibition and polymer healing effects of polyolefin coatings modified with Ce-loaded hydroxyapatite particles applied on steel

pH-sensitive hydroxyapatite particles were loaded with cerium ions (Ce-HAP) and incorporated into polyolefin coatings applied on carbon steel. The Ce-modified hydroxyapatite particles were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The protective performance of modified and reference polyolefin coatings applied on carbon steel was studied by electrochemical impedance spectroscopy (EIS), and the self-healing capability was evidenced by combining the scanning vibrating electrode technique (SVET) and pH micro-potentiometry with video-imaging, SEM and Raman. The modified coatings showed significantly improved long-term corrosion protection compared to reference coatings. The effect was attributed to the synergistic combination of the corrosion inhibition effect of cerium ions loaded in the HAP particles and polyolefin healing capability.

Physico-chemical and biological behaviour of eggshell bio-waste derived nano-hydroxyapatite matured at different aging time

The present study explores the effect of aging time on the properties of nano-hydroxyapatite (HAp) synthesized from chicken eggshells. CaO obtained from eggshells serves as calcium precursor which is combined with di-sodium hydrogen phosphate (Na2HPO4) as a phosphate precursor for the synthesis of HAp. The reaction precipitate is allowed to mature considering aging times of 12, 24, 36 and 48 h. The synthesized powders are characterized using FTIR and XRD to confirm the HAp formation. SEM micrographs of all the aged samples reveal dense agglomerated HAp particles. It is observed from the TEM results that the particle morphology of all the HAp samples appears to be nano-sized, spherical-shaped and polycrystalline in nature. A novel relationship between relative density vs. aging time is also established where relative density is found to increase with an increase in the aging time. In- vitro bioactivity and biodegradability evaluation of 12 h aged HAp with best physico-chemical properties show the formation of HCA apatite layer and significant weight loss respectively. In-vitro cytotoxicity test with Human Wharton’s Jelly Mesenchymal Stem Cells (hMSCs) (HiMedia CL001-T25) shows approximately 90 % cell viability assuring non-cytotoxicity of the 12 h aged HAp. The derived HAp can be a possible regenerative biomaterial for bone tissue engineering applications.

Characterization of UHMWPE- HAp coating produced by dip coating method on Ti6Al4V alloy

In the present study, the surface of Ti6Al4V alloy was coated with UHMWPE-HAp composite film by dip coating for hip joint material. Ti6Al4V alloy surfaces were firstly roughened by anodic oxidation to provide adhesion of the polymer coating on it. Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FE-SEM) results showed that the UHMWPE-HAp composite film was coated homogenously on the substrate and HAp particles were well bonded to the matrix. Functional groups and bond types of the composite coatings were detected by Fourier-transform Infrared Spectroscopy (FTIR). The melting temperature T m and the enthalpy of fusion (ΔH f ) of the UHMWPE and UHMWPE-HAp composite coatings were measured by differential scanning calorimetry (DSC). The crystallinities were calculated as 24.5% for pure UHMWPE and increased to 54.2% by addition of 1 wt%HAp particles into the UHMWPE matrix. Dry sliding wear properties of coatings against alumina ball were tested by a ball-on-disc tribometer in linear mode. Wear results revealed that UHMWPE-HAp composite coating on anodic oxidized Ti6Al4V alloy has an ultra-low friction coefficient of 0.06 compared to the friction coefficient of anodic oxidized Ti6AlV4 alloy at of 0.8 and with a favorable wear resistance 84% higher than oxide coated ones. This newly developed composite coating material shows potential use for artificial hip joint replacements. • Ti6Al4V alloy surfaces were coated by combination of porous TiO 2 layer and UHMWPE-HAp composite • Crystallinity of pure UHMWPE increased by 121% by incorporating of 1 wt.% HAp • Extreme increase in crystallinity provided excellent wear resistance with ultra low friction coefficient of 0.06 • No pilling -up of polymer film was observed after scratch test that is mainly due to the high sticking force of polymer film to the substrate. • UHMWPE-HAp composite coating on Ti6Al4V alloy has potential for application on acetabular cup of artificial hip joint replacements.