Hydroxyapatite Samples Research Articles

Preparation and properties of artificial bone with lead-free piezoelectric materials

In order to fabricate the artificial bone with high bioactive property, lead-free barium titanate (BaTiO3, BT) piezoelectric material added hydroxyapatite (HA) composites were prepared in this study. Compared with the pure HA materials, the introduction of BT can increase the electrical properties of the samples while ensuring good biological properties. The electrical properties, such as piezoelectric constant d33, hysteresis loop and dielectric spectrum were measured, respectively. The bending strength, Vickers hardness, cytotoxicity and osteogenic property of the BT/HA composites were also discussed. It is revealed that the non-toxic sample with 95 wt% BT and 5 wt% HA (95BT+5HA) has the best osteoinductivity, the piezoelectric constant d33 of which is 79.2 pC N-1. The bending strength and Vickers hardness of the 95BT+5HA sample are 138.3 MPa and 472.4, respectively, realizing the desired mechanical properties of human bones. Comprehensive analyses of various properties show that the 95BT+5HA composite can meet the requirements of artificial bone, and is expected to be a promising generation of substitute bone materials.

Reaction of stoichiometric hydroxyapatite with different crystallinity in Mg<sup>2+</sup> aqueous solution

The reaction of stoichiometric hydroxyapatite (HAp) with different crystallinity in Mg2+ aqueous solution was investigated using X-ray absorption near edge structure (XANES). Crystallinity is one of important factors for the properties of HAp. Therefore, this study aimed to clarify the effect of crystallinity on the behavior of HAp in aqueous solutions. Stoichiometric HAp samples with different crystallinities were prepared using an aqueous solution precipitation method and subsequent calcination. The Mg-K XANES spectra of the HAp pellets after immersing in Mg(NO3)2 aqueous solution were classified into two groups: those of Mg-doped HAp and Mg(OH)2. This difference is caused by the solubility of the HAp pellets in water, owing to their crystallinity. This result provides insights into the reaction mechanism of HAp in the human body and facilitates selection of suitable biomaterials.

Synthesis and Biological Properties of Alanine-Grafted Hydroxyapatite Nanoparticles.

Hydroxyapatite attracts great attention as hard tissues implant material for bones and teeth. Its application in reconstructive medicine depends on its biocompatibility, which is in a function of composition and surface properties. The insertion of a protein element in the composition of implants can improve the cell adhesion and the osseointegration. Having this in mind, the proposal of this work was to develop L-alanine-grafted hydroxyapatite nanoparticles and to study their biocompatibility. Two L-alanine sources and three grafting methods were used for hydroxyapatite surface functionalization. The efficiency of grafting was determined based on X-ray powder diffraction, Fourier-transform infrared spectroscopy, thermal analyses, and field-emission scanning electron microscopy. The results indicated the formation of hydroxyapatite with 8-25 wt% of organic content, depending on the grafting method. Protein adsorption, cell adhesion, and viability studies were carried out to evaluate biological properties of grafted materials. The viability of MG-63 human osteoblastic cells following 24 h incubation with the alanine-grafted hydroxyapatite samples is well preserved, being in all cases above the viability of cells incubated with hydroxyapatite. The alanine-grafted hydroxyapatite prepared in situ and by simple mixture showed higher protein adsorption and cell adhesion, respectively, indicating their potential toward use in regenerative medicine.

Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions.

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr2+ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr2+ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr2+ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr2+ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr2+ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr2+ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr2+ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.

Fabrication of hydroxyapatite porous body with connective pores using the self-networking property of rice starch powder by heat treatment

• Porous hydroxyapatite ceramics was fabricated. • Gelatinization-retrogradation phenomena of starch was used as pore-networking agent. • Randomly-developed open pores were introduced into the hydroxyapatite matrix. • Pore structure was characterized by confocal scanning laser fluorescence microscopy. Hydroxyapatite porous ceramics were fabricated utilizing the property called gelatinization-retrogradation in which starch particles used as a pore-forming agent form a self-network structure by heat treatment. The pore structures in the hydroxyapatite samples were observed by combining the immersion transmission method and a confocal scanning laser fluorescence microscope. The three-dimensional image created by stacking the cross-sectional observation images showed that randomly-developed open pores were introduced into the matrix.

CTAB enabled microwave-hydrothermal assisted mesoporous Zn-doped hydroxyapatite nanorods synthesis using bio-waste Nodipecten nodosus scallop for biomedical implant applications

In biomedical exploration, the predominant characteristic is synthesizing and fabricating multifunctional nanostructure with intensified biocompatibility and excellent antibacterial applications to avoid post-surgical implant failure. The objective of the current study is to examine ideal mesoporous zinc-doped hydroxyapatite (HAp) for future use in the field of biomedical research. In the present investigation, we synthesized mesoporous Zn-doped HAp nanorods with varied mole concentrations using a profound microwave hydrothermal method utilizing bio-waste Nodipecten nodosus scallop as a calcium source and CTAB as an organic modifier. Bio-waste Nodipecten nodosus scallop is a widely available cheap calcium precursor which is converted into pure and zinc-doped hydroxyapatite nanorods with the help of the microwave hydrothermal method. Different analytical techniques like spectroscopy and electron microscopy were employed to evaluate and precisely characterize the structural and morphological characteristics in synthesized pure and mesoporous Zn-doped HAp nanorods. CTAB and microwave hydrothermal methods successfully create mesoporous Zn-doped hydroxyapatite nanorods with different sizes and morphology. Mesoporous Zinc-doped HAp nanorods show excellent antibacterial activity against Klebsiella pneumoniae (MTCC 7407) and Bacillus subtilis (MTCC 1133), compared to other nanorods. ZnHAp-3 shows notable excellent results of antibacterial effect towards K. pneumoniae and B. subtilis, by exhibiting 12.36 ± 0.12 and 13.12 ± 0.16 mm zone of inhibition. Furthermore, ZnHAp-1 shows the lower zone of inhibition, while the ZnHAp-3 sample shows the highest zone of inhibition. A foremost study performed was toxicity assays to validate safe attributes of mesoporous zinc-doped HAp intensified with the proliferation function of the zebrafish model. The results reveal the non-toxic behavior of pure and mesoporous zinc-doped HAp samples. Thus, our studies provide evidence for the synthesis technique for the mesoporous zinc-doped HAp nanorods using a novel CTAB-enabled microwave hydrothermal method utilizing bio-waste Nodipecten nodosus scallop as a calcium source will be alternative affordable biocidal antibacterial materials for controlling post-surgical implant failures.

Effect of doping cation on the adsorption properties of hydroxyapatite to uranium

Hydroxyapatite samples doped with different metal ions (HAP-M, M ​= ​Cu, Sr, Al, Ce, and Ti) were successfully prepared by a simple co-precipitation method for effective U(VI) uptake. The applications of HAP-M in capturing U(VI) were investigated. Besides, numerous characterizations were taken to study the chemical and physical properties of HAP-M. The critical factors affecting U(VI) adsorption were examined, such as pH, contact time, initial concentration of U(VI) and solution temperature. The present study revealed that the adsorption effect of HAP for U(VI) can be affected by doping metal cations with different ionic radii, and HAP doping with Ti4+ ions increased its adsorption selectivity to U(VI). With the increase of the molar ratio of doped Ti4+ ions (5%–20%), the adsorption selection of U(VI) on HAP-Ti is also gradually increasing. HAP-Ti is a potentially efficient adsorbent in removing U(VI) from radioactive solutions.

Synthesis of Alginate/Hydroxyapatite Beads for Acetaminophen Delivery

Conventional drug delivery systems usually involve the intake of multiple drugs, which could amplify the risk of overdosing. Acetaminophen is a widely used pain relief substance that is prone to accidental overdosing. Hence, a controlled drug delivery system is needed to ensure its efficacy. A nanocomposite hydroxyapatite/alginate system that was used as a drug carrier for acetaminophen was synthesized through the sol-gel method, and the mechanism underlying its controlled drug delivery was investigated. Spherical nanocomposite bead samples were synthesized by incorporating 5 wt%, 10 wt%, and 15 wt% hydroxyapatite into mixtures containing alginate. The mixtures were then dropped into calcium chloride solution. The phase purity of the hydroxyapatite sample was confirmed through X-ray diffraction, and the functional groups that confirmed the presence of alginate and hydroxyapatite in the nanocomposite samples were analyzed by using Fourier transform infrared spectroscopy. The release of acetaminophen can be controlled for 48 h, and the Korsmeyer–Peppas kinetics model showed the best correlation for all samples. The kinetics of Al/HAp5, Al/HAp10, and Al/HAp15 were governed by quasi-Fickian diffusion with the n values of 0.199, 0.238, and 0.225, respectively. The composite beads show potential for application as a controlled drug delivery vehicle.

Zinc-Silver Doped Mesoporous Hydroxyapatite Synthesized via Ultrasonic in Combination with Sol-Gel Method for Increased Antibacterial Activity

Bone materials are mainly composed of an inorganic constituent called hydroxyapatite (HA). In the current study, mesoporous Zn2+/Ag+ doped hydroxyapatite nanoparticles (Zn-Ag doped HA) with high antibacterial activity were synthesized through ultrasonic coupled sol-gel techniques under calcination temperatures of 600 °C for 4 h and 1100 °C for 1 h. The variance in the molar ratio of Zn2+/Ag+ in Ca9.0Zn1.0−xAgx(PO4)6(OH)2 (x = 0.0, 0.25 to 1.0) and its effects on the chemical and physical properties of the powdered samples were investigated. The results show that the hexagonal framework of HA incorporated both the Zn2+ and Ag+ ions and the rhombohedral structure of β-TCP. The main functional groups of HA and Zn-Ag doped HA samples were hydroxyl and phosphate. All samples have mesoporous characteristics with a Type IV isotherm. The agar well diffusion process was used to examine antibacterial activity against E. coli, P. aeruginosa, S. aureus, B. cereus and B. subtilis. Effective antibacterial activity was displayed by Zn-Ag doped HA. Excellent antibacterial performance was shown by Ca9.0Zn0.75Ag0.25(PO4)6(OH)2 against all tested bacterial strains, except P. aeruginosa. This material showed inhibition zones ranging from 7 to 11 mm, implying that it is a suitable material with an antibacterial action for environmental applications, specifically for water purification.

Development and evaluation of hydroxytite-based anti-microbial surface coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloys for overall biofunctionality

The current investigation aims to develop hydroxyapatite-based biofunctional composite coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloy implant specimens for orthopedic uses. The porous 3D-printed implants based on Ashby Gibson’s mathematical model for cellular materials are fabricated at a 65% level of porosity, so as to attain the mechanical strength of human bones. Further, the addition of strontium and silver in hydroxyapatite for improved biocompatibility of the 3D-printed implant to enhance its biofunctionality and its validation is performed. The resulting coated substrates are subjected to a series of morphological, elemental, phase, mechanical, and biological tests. When subjected to the uniaxial compression, the values for modulus of elasticity and yield strength of 3D-printed substrates are compared to the targeted value of elastic modulus and yield strength for the human bones (10–30 GPa and 148–240 MPa, respectively). The effect of polydopamine-treated 3D-printed Ti6Al4V substrates on the coating compositions of calcium and phosphorus has been compared to the untreated samples. The coating thickness and adhesion strength have been calculated and compared for different coating groups. All the samples, except untreated pure hydroxyapatite samples, displayed antimicrobial activity for both the gram-positive and gram-negative bacteria in the zone inhibition test. Hence, the current experiment provides a novel option to fabricate porous Ti6Al4V scaffolds, with a low-temperature surface coating to attain improved biofunctionality for orthopedic applications.

The study of the interactions of malonic acid ions with the hydroxyapatite surface in liquid

• Adsorption is described by the multiexponantiate model. • The last stage of the adsorption kinetics indicates the process of precipitation of a new phase. • Adsorption of malonic acid is best described by the Redlich-Paterson isotherm model. • The presence of adsorbed malonate ions causes an increase in the concentration of acid groups on the hydroxyapatite surface. Adsorption of malonic acid at the hydroxyapatite/aqueous NaCl solution interface based on the measurements of adsorption / desorption kinetics and adsorption as a function of pH was presented. The adsorption of malonate ions was determined from the loss of ion concentration in the solution as measured by the radioisotope using 14C labeled malonic acid. The adsorption measurements were supplemented with electrophoretic zeta potential as well as and FTIR measurements. The kinetics of adsorption from a solution with an initial concentration of 1 mmol/dm3 of malonic acid proceeds in three stages, in the last stage there was observed a rapid increase in adsorption, which proves the precipitation of a new phase by the malonate ions. The presence of this phase was confirmed by examining the crystallinity of the hydroxyapatite sample conditioned in a malonic acid solution by the method of Landi et al. on the basis of XRD patterns and measurements of particle distribution using the light scattering method.

Experimental characterization and theoretical investigation of [formula omitted] co-doped hydroxyapatites

In this study, the wet chemical method was used to synthesize Zn-doped hydroxyapatite (HAp) samples, and the effects of varying the amount of Sm addition on structural, thermal, and biocompatibility in vitro properties were studied. In addition, a density functional theory was used for modeling the as-synthesized samples to obtain the theoretical calculation results. XRD results confirmed the formation of biphasic compositions for all samples, and FTIR data supported the formation of the functional groups of hydroxyl and phosphate. More than 98% of samples showed the formation of the HAp phase. The addition of Sm resulted in an increase in the secondary phase of the β-TCP from 0.60% to 1.49%. The lattice parameters (aandc),unit cell volume (V), lattice strain(ε), and lattice stressσ varied when Sm was added as a dopant. The crystallite size and crystallinity decreased as the Sm content increased, however, the anisotropic energy density gradually increased. Thermal analysis results confirmed that all samples seemed to be thermally stable. The addition of Sm did not result in any notable morphological modifications. Cell viability values of theZn-based HAp sharply decreased as a result of an increase in the Sm additive. Theoretical studies show that when the amount of Sm in the Zn-based HAp structure increases, the bandgap energy decreases from 4.68 to 4.40eV. An increasing density and decreasing unit cell volume have been observed, as confirmed by the theoretical results. In addition, there was a decrease in crystallinity as well as an increase in anisotropic energy density.

Comparative study of certain substituted ions in hydroxyapatite: characterization and effect on cell viability

Hydroxyapatite (HA) is a biomaterial that has been widely studied for uses such as bone grafting and tissue engineering. Pure and hydroxyapatite nanoparticles with cationic (Na, Ti, and Li) as well as anionic ( and Si4+) substitutions were synthesised using a wet chemical precipitation method followed by freeze-drying and investigated for their cytotoxicity effect. Inductively coupled plasma (ICP), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were used to characterise the produced powders. The production of the HA phase was confirmed in all synthesised HA samples. MTT (3-(4.5-dimethylthiazol-2-yl)−2.5-diphenyl tetrazolium bromide) assay was performed using the BJ1 cell line of human normal fibroblasts to investigate the cytotoxicity of the synthesised HA samples. The cytotoxicity test showed that the HA samples were biocompatible, with the greatest results coming from Li-substituted (LiHA2) and Na-substituted (NaHA) hydroxyapatite.

Investigation of structural, spectroscopic, dielectric, magnetic, and in vitro biocompatibility properties of Sr/Ni co-doped hydroxyapatites

In this study, the changes caused by Ni and Sr additives on the structural, thermal, dielectric, and magnetic properties of hydroxyapatite (HAp) samples were examined and reported for the first time in detail.Some effects of the Sr/Ni site disorder on the crystallographic, dielectric, and magnetic properties in Sr/Ni-HAp have been examined, as well as their cytotoxicity effects. The addition of Ni affected the morphology of nanoparticles with a low agglomeration increase. Our results showed that the dielectric constant (ε′) and dielectric loss (ε′′) have greater values at low frequencies than at higher frequencies for all the samples.It can be concluded that Ni and Sr additions to the HAp structure contribute to the development of thermal, magnetic, and dielectric properties required to mimic natural HAp in the study conducted with the idea of creating a medical application area for bone healing and regeneration. The cytotoxicity test of the produced nanoparticles and the evaluation of the results were also performed using human foreskin fibroblasts (HFF). The viability of cells after treatment for 48 h ranged between 50 and 75%. While 0.37Ni-0.37Sr-HAp and 1.11Ni-0.37Sr-HAp were similar to 0.37Sr-HAp, 0.74Ni-0.37Sr-HAp had the highest cellular viability. At 0.1 mg/mL, 0.74Ni-0.37Sr-HAp had a viability of 79.97% compared to the untreated control cells. Our Sr/Ni-HAp nanoparticles have promising medical applications in bone healing and regeneration.

Evaluation of hydroxyapatite-based cement for geothermal well applications

The working fluid in geothermal wells often contains naturally occurring CO2. In an aqueous environment, CO2 forms carbonic acid and subsequently reacts with the binding components of cement, resulting in the loss of strength and early failure. Well cement formulations containing hydroxyapatite (HOAP) are considered resistant to the carbonic acid attack. The main goal of this work is to study the effects of hydroxyapatite on cement degradation in high-pressure, high-temperature (HPHT) acidic environments. For evaluating the carbonic acid resistance of HOAP cement, aging experiments were conducted using cement cores and shear-bond test specimens. The aging temperature, pressure, and CO2 content of the gas were varied. After aging, the cores and specimens were recovered and tested to assess the level of degradation based on variation in bond and compressive strengths, porosity, permeability, and mineralogical composition. The results showed that HOAP cement has better resistance to carbonic acid attack than the baseline cement that does not contain hydroxyapatite. Nevertheless, due to the lack of silica flour, HOAP samples were thermally degraded after aging under extremely harsh conditions and exhibited high permeability due to the formation of microcracks.

New strumming sleight for old tunes: Exploration on the sorption mechanisms of Cd(II) by hydroxyapatite synthesized with different molar Ca/P ratios

Hydroxyapatite (HAP) has been widely used for the preconcentration and stabilization of various heavy metal pollutants in both the water and soil environment. Nonetheless, there still exists a gap between its synthesis conditions, physicochemical properties and removal performances. Under such a research background, three HAP materials were synthesized via a modified co-precipitation approach by varying initial Ca/P molar ratios (i.e., 4/3, 5/3 and 6/3) and used for capturing toxic cadmium (Cd(II)) from an aqueous solution. According to the experimental results, the three synthesized HAP samples were all the Ca-deficient type and the actual Ca/P molar ratio was in the increasing order of HAP4/3 < HAP5/3 < HAP6/3. In particular, the HAP4/3 sample exhibited higher Cd(II) removal performance due to its higher specific surface area (SSA) value and abundant Ca-deficient sites. More than 93% of Cd(II) was removed within an extremely short period of 5 min and a complete removal was achieved at a prolonged contact time of 24 h. The sorption behavior of Cd(II) was independent of ionic strength variation and scarcely influenced by various inorganic electrolyte ions, low molecular weight organic acids (LMWOAs) and competing heavy metal ions. The desorption data of Cd(II)-containing HAP phases, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses pointed to a predominant removal mechanism of lattice incorporation with a minor contribution of inner-sphere surface complexation. The experimental findings demonstrated the significant application potential of Ca-deficient HAP material for the cost-effective treatment of Cd(II)-polluted water systems.

The experimental and theoretical investigation of Sm/Mg co-doped hydroxyapatites

This study presents an extensive experimental and theoretical analysis of Mg-doped hydroxyapatite (HAp) samples with additional Sm doping at varying amounts. A wet chemical method was used to synthesize Mg-containing HAps at a constant amount of 0.133at.%, and in addition the second dopant of Sm was utilized at varying amounts of 0.133,0.266,0.399,0.532, and 0.665at.%. All of these samples were investigated experimentally and theoretically by using the X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), in-vitro cell viability tests, and density functional theory (DFT) calculations. The bandgap energy was found to have reduced from 4.6115 eV to 4.3870 eV. The linear attenuation (or absorption) coefficient increased as the amount of Sm in the sample increased, and this parameter decreased as the photon energy increased for all samples. Both the lattice parameter and the theoretical density increased, whereas the unit cell volume and the lattice parameters declined. The XRD and FTIR results revealed that the HAp phase (over 98 percent for all samples) was a major phase formed, while the β-TCP phase (beta-tricalcium phosphate) was a minor phase. The β-TCP phase increased from 0.91to1.57 percent with an increasing amount of Sm. The volume of the unit cell trended in the same direction as predicted by the obtained results theoretically. Increased anisotropic energy density and a decrease in crystallinity have been observed. All samples were found to be thermally stable. Due to the presence of Sm content, cell viability was observed to be affected.

Investigation and ANN-based prediction of the radiation shielding, structural and mechanical properties of the Hydroxyapatite (HAP) bio-composite as artificial bone

This paper focuses on the radiation shielding, structural and specifically mechanical features of the Hydroxyapatite (HAP) bio-composites which can be used instead of the bone and tooth tissues in the human body via FLUKA Monte Carlo Code (FMCC), Phy-X: PSD software, and an analytical method. Since HAP bio-composites are so brittle, their use is limited instead of bone in the human body. This challenging issue persuaded the scientists and researchers to solve the problem by inserting various oxide or dioxide materials into HAP bio-composites. Thus, in this work, TiO2 and CeO2 with different ratios of x = 0, 3, 7.5, 10 wt.% and y = 0, 2, 6, 7.5 wt.% are inserted into HAP bio-composites and thus eight types of S (S1, S2, S3, and S4) and B (B1, B2, B3, and B4) samples are produced. Using Artificial Neural Network (ANN), this study predicts and demonstrates the system's behavior. Outcomes reveal that increasing the TiO2 and CeO2 concentrations in the (100-x) HAP + xTiO2 and (100-y) HAP + yCeO2 bio-composites will improve the gamma photon shielding performance of the S and B samples. Furthermore, the photon and electron spatial maps for simulated geometries related to the S4 sample are extracted by the FLUKA Monte Carlo Code and are represented graphically. The produced electrons with the highest energy are monitored in lead volumes due to various interactions of gamma photons with lead shields. In addition, sharp peaks are reported for Zeff curves related to the B samples which may be due to the K-edge absorption of the Ce in HAP samples. The FLUKA results are in full agreement with the predicted targets via the ANN algorithm. Moreover, increasing the CeO2/TiO2 concentrations in HAP bio-composites will enhance the rigidity of the chosen S and B samples. The rising percentage of the mechanical moduli related to the S and B series vary between 30% and 90% which may be due to the relationship between the density of the selected HAP bio-composites and mechanical moduli.

Osteoblastic Cell Responses of Copper Nanoparticle Coatings on Ti-6Al-7Nb Alloy Using Electrophoretic Deposition Method.

Aim To investigate and compare the cell cytotoxicity, proliferation, cell attachment, and morphology of human fetal osteoblasts (hFOB) cells of coated samples (titanium nanocopper (Ti Cu), titanium nanohydroxyapatite (Ti HA) and titanium nanocopper ion doped hydroxyapatite (Ti Cu/HA) and uncoated samples (Ti) in order to assess the suitability of these surface modifications on Ti-6Al-7Nb for dental implant application. Materials and Methods The cytotoxicity was studied by examining the hFOB cell response by MTT assessment. The cell morphology was evaluated by inverted microscopy and observed under scanning electronic microscopy (SEM). Results MTT assay results displayed that the Cu content on the surface of Ti-6Al-7Nb alloys did not produce any cytotoxic effect on cell viability. The cell viability rate in all samples ranges from 97% to 126%, indicating that hFOB cells grew at a high proliferation rate. However, no significant differences in cell viability were observed between Ti and Ti Cu and between Ti HA and Ti Cu/HA groups. Microscopic examination demonstrated no difference in the cell morphology of hFOB among all samples. In addition, SEM observation indicated favorable adhesion and spreading of the cells on the coated and uncoated samples. Conclusions The surface modification of Ti-6Al-7Nb alloy with Cu, HA, and Cu/HA exhibits good cell biocompatibility, and the Cu has no influence on the cell proliferation and differentiation of hFOB.

Effects of the doping concentration of boron on physicochemical, mechanical, and biological properties of hydroxyapatite

Ion doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa–0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, 260 μg/l and 770 μg/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release ≤260 μg/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.