Hydroxyapatite Content Research Articles

Bone Density Variation in Rattails (Macrouridae, Gadiformes): Buoyancy, Depth, Body Size, and Feeding.

Extreme abiotic factors in deep-sea environments, such as near-freezing temperatures, low light, and high hydrostatic pressure, drive the evolution of adaptations that allow organisms to survive under these conditions. Pelagic and benthopelagic fishes that have invaded the deep sea face physiological challenges from increased compression of gasses at depth, which limits the use of gas cavities as a buoyancy aid. One adaptation observed in deep-sea fishes to increase buoyancy is a decrease of high-density tissues. In this study, we analyze mineralization of high-density skeletal tissue in rattails (family Macrouridae), a group of widespread benthopelagic fishes that occur from surface waters to greater than 7000 m depth. We test the hypothesis that rattail species decrease bone density with increasing habitat depth as an adaptation to maintaining buoyancy while living under high hydrostatic pressures. We performed micro-computed tomography (micro-CT) scans on 15 species and 20 specimens of rattails and included two standards of known hydroxyapatite concentration (phantoms) to approximate voxel brightness to bone density. Bone density was compared across four bones (eleventh vertebra, lower jaw, pelvic girdle, and first dorsal-fin pterygiophore). On average, the lower jaw was significantly denser than the other bones. We found no correlation between bone density and depth or between bone density and phylogenetic relationships. Instead, we observed that bone density increases with increasing specimen length within and between species. This study adds to the growing body of work that suggests bone density can increase with growth in fishes, and that bone density does not vary in a straightforward way with depth.

On the use on hydroxyapatite suspensions for the separation of milk fat globule membrane components from buttermilk

The milk fat globule membrane (MFGM), which surrounds and stabilizes the fat globules, is released in buttermilk during cream churning. MFGM has many health benefits due to its composition rich in phospholipids and membrane proteins. Many techniques have been tried to separate the MFGM from the remaining milk solids non-fat, but they are challenging to carry out at an industrial scale. This research proposes a new approach to separating MFGM from buttermilk. This paper assessed the efficacy of hydroxyapatite (HA) cristal in interacting with MFGM isolates obtained from either raw or pasteurized cream. Different HA to MFGM ratios were used (10:1 and 20:1) to determine the impact of HA concentration on the adsorption. The results showed a very high affinity of the MFGM for HA and suggested the potential for its separation from buttermilk to improve its valorization.

Evaluation of the mechanical properties of hydroxyapatite-silica aerogel/epoxy nanocomposites: Optimizing by response surface approach

This study attempted to investigate the effects of adding hydroxyapatite and silica aerogel nanoparticles on the density, tensile, Izod impact, and morphological properties of epoxy using the Response Surface Methodology (RSM). RSM relied on Box–Behnken Design (BBD) was used to design the mechanical tests. The concurrent effects of two parameters including hydroxyapatite content and silica aerogels content on the mechanical properties have been evaluated. Finally, by using the equations obtained from regression for each of the responses, their optimal states were obtained using both the desirability approach and the Multi-Objective Particle Swarm Optimization (MOPSO) method. The results from tensile, and Izod impact tests indicated the combination of hydroxyapatite and silica aerogel nanoparticles led to an improvement in the tensile properties and energy absorption of epoxy matrix. The findings related to density test demonstrated that with addition of silica aerogel to the hydroxyapatite/epoxy nanocomposites, density of these samples was decreased. The maximum tensile strength of 86.9 MPa was obtained with hydroxyapatite content of 2.38 wt% and silica aerogels content of 4 wt%. Also, the maximum impact strength of 18.14 kJ/m2 was obtained with hydroxyapatite content of 1.11 wt% and silica aerogels content of 3.51 wt%. The field emission scanning electron microscope images showed the homogeneous distribution of combined hydroxyapatite and silica aerogel nanoparticles in epoxy matrix, except in 5 wt% of hydroxyapatite nanoparticles.

The Effect of Germanium-Loaded Hydroxyapatite Biomaterials on Bone Marrow Mesenchymal Stem Cells Growth.

Hydroxyapatite (HA) is a hard mineral component of mineralized tissues, mainly composed of calcium and phosphate. Due to its bioavailability, HA is potentially used for the repair and regeneration of mineralized tissues. For this purpose, the properties of HA are significantly improved by adding natural and synthetic materials. In this sense, the germanium (Ge) mineral was loaded in HA biomaterial by cold isostatic pressure for the first time and characterization and biocompatibility using bone marrow mesenchymal stem cells (BM-MSCs) were investigated. The addition of Ge at 5% improved the solubility (3.32%), stiffness (18.34 MPa), water holding (31.27%) and biodegradation (21.87%) properties of HA, compared to control. Compared to all composite biomaterials, the drug-releasing behavior of HA-3% Ge was higher at pH 1 and 3 and the maximum drug release was obtained at pH 7 and 9 with HA-5% Ge biomaterials. Among the different mediums tested, the DMEM-medium showed a higher drug release rate, especially at 60 min. HA-Ge biomaterials showed better protein adhesion and apatite layer formation, which ultimately proves the compatibility in BM-MSCs culture. Except for higher concentrations of HA (5 and 10 mg/mL), the different concentrations of Ge and HA and wells coated with 1% of HA-1% Ge had higher BM-MSCs growth than control. All these findings concluded that the fabricated HA biomaterials loaded with Ge could be the potential biomaterial for culturing mammalian cells towards mineralized tissue repair and regeneration.

Additive manufactured polyether-ether-ketone composite scaffolds with hydroxyapatite filler and porous structure promoted the integration with soft tissue

Additive Manufactured (AM) Polyether-ether-ketone (PEEK) orthopaedic implants offer new opportunities for bone substitutes. However, owing to its chemical inertness, the integration between PEEK implants and soft tissue represents a major challenge threatening the early success of the PEEK implants. Here we investigated the influence of hydroxyapatite (HA) fillers and porous structure of AM HA/PEEK scaffolds on the integration with soft tissue through in-vitro cellular experiments and in-vivo rabbit experiments. Among the animal experiments, HA/PEEK composite scaffolds with HA contents of 0, 20 wt%, 40 wt% and pore sizes of 0.8 mm, 1.6 mm were manufactured by fused filament fabrication. The results indicated that HA promoted the proliferation and adhesion of myofibroblasts on PEEK-based composites by releasing Ca2+ to active FAK and its downstream proteins, while the surface morphology of the scaffolds was also roughened by the HA particles, both of which led to the tighter adhesion between HA/PEEK scaffolds and soft tissue in-vivo. The macroscopic bonding force between soft tissue and scaffolds was dominated by the pore size of the scaffolds but was hardly affected by neither the HA content and nor the surface morphology. Scaffolds with larger pore size bonded more strongly to the soft tissue, and the maximum bonding force reached to 5.61 ± 2.55 N for 40 wt% HA/PEEK scaffolds with pore size of 1.6 mm, which was higher than that between natural bone and soft tissue of rabbits. Although the larger pore size and higher HA content of the PEEK-based scaffolds facilitated the bonding with the soft tissue, the consequent outcome of reduced mechanical properties has to be compromised in the design of the porous PEEK-based composite implants. The present study provides engineering-accessible synergistic strategies on material components and porous architecture of AM PEEK orthopaedic implants for improving the integration with soft tissue.

Development of pH-sensitive biomaterial-based nanocomposite for highly controlled drug release

Combining non-toxic biomaterials to obtain high effective hybrids is a promising approach in medicine and drug delivery. This study aims to combine the biomaterial with different swelling behavior to attain high controlled release. Hydroxyapatite (HA) nanoparticles do not possess swelling properties and are stable in different pH solutions. HA was used to prevent the unwanted sudden release in acidic media by modifying the swelling properties of chitosan-based hydrogels (CTS). CTS being soluble in acidic pHs causes drug release as it dissolves, resulting in burst release behavior. The experiments confirmed that the introduction of HA remarkably reduced the swelling ratio, which independent of the pH led to a decrease in the release amount (approximately 38–73%) and prevented the burst release. The metronidazole-loaded CTS/MMt/HA1 with low content HA showed a high sustained pH-responsive release. However, the metronidazole-loaded CTS/MMt/HA2 with high content of HA didn't show sustained release. Indeed, the release rate was sustained by modifying the HA content. The kinetic investigations indicated the release mechanisms were changed from dissolution in CTS/MMt to diffusion in CTS/MMt/HA by introducing HA, which is compatible with the swelling ratio reduction. As well as CTS/MMt, HA grafted samples showed high encapsulation efficiency (>96%) and pH-sensitive properties. The biocompatibility of Metronidazole-loaded nanocomposites was confirmed by the cytotoxicity tests on the human nasopharyngeal carcinoma L929 cells.

Bioactive Composite for Orbital Floor Repair and Regeneration.

In the maxillofacial area, specifically the orbital floor, injuries can cause bone deformities in the head and face that are difficult to repair or regenerate. Treatment methodologies include use of polymers, metal, ceramics on their own and in combinations mainly for repair purposes, but little attention has been paid to identify suitable materials for orbital floor regeneration. Polyurethane (PU) and hydroxyapatite (HA) micro- or nano- sized with different percentages (25%, 40% & 60%) were used to fabricate bioactive tissue engineering (TE) scaffolds using solvent casting and particulate leaching methods. Mechanical and physical characterisation of TE scaffolds was investigated by tensile tests and SEM respectively. Chemical and structural properties of PU and PU/HA scaffolds were evaluated by infrared (IR) spectroscopy and Surface properties of the bioactive scaffold were analysed using attenuated total reflectance (ATR) sampling accessory coupled with IR. Cell viability, collagen formed, VEGF protein amount and vascularisation of bioactive TE scaffold were studied. IR characterisation confirmed the integration of HA in composite scaffolds, while ATR confirmed the significant amount of HA present at the top surface of the scaffold, which was a primary objective. The SEM images confirmed the pores’ interconnectivity. Increasing the content of HA up to 40% led to an improvement in mechanical properties, and the incorporation of nano-HA was more promising than that of micro-HA. Cell viability assays (using MG63) confirmed biocompatibility and CAM assays confirmed vascularization, demonstrating that HA enhances vascularization. These properties make the resulting biomaterials very useful for orbital floor repair and regeneration.

Effect of Hydroxyapatite Synthesized from Tilapia Fish Scale Waste on the Shear Bond Strength of GIC and RMGIC to Enamel Layer (<i>In Vitro</i> Study)

Indonesia is a country that has many types of freshwater fish, one of which is tilapia. The consumption of tilapia among the people of Indonesia is quite high. So that, it will produce a lot of fish scale waste. Fish scales can be used as a natural source of hydroxyapatite because they contain calcium. The aim of this study was to evaluate the effect of hydroxyapatite synthesized from tilapia fish scale (Oreochromis niloticus) on the shear bond strength of glass ionomer cement and resin modified glass ionomer cement to enamel layer. Hydroxyapatite was synthesized from tilapia fish scale (Oreochromis niloticus) by calcination method at 800°C. Sample was made from glass ionomer cement (GIC) and resin modified glass ionomer cement (RMGIC) combined with 2, 5 and 8%wt of hydroxyapatite, respectively. Sample was bonded to enamel layer of human premolar tooth. The shear bond strength of sample was tested by using Universal Testing Machine. The result showed that shear bond strength were increased for higher concentration of hydroxyapatite that added to glass ionomer cement or resin modified glass ionomer cement. The maximum of shear bond strength of GIC Group is 6,38 ± 0,05MPa after 8%wt hydroxyapatite addition. The maximum of shear bond strength of RMGIC Group is 6,59 ± 0,06 MPa after 8%wt hydroxyapatite addition. There were significance differences among all group tested (p <0.05). It can be concluded that hydroxyapatite synthesized from tylapia fish scale can increase the shear bond strength of glass ionomer cement and resin modified glass ionomer cement.

Effect of intravenous iodinated contrast administration on diagnostic ability for osteoporosis using CT attenuation measurement in patients with liver cirrhosis.

To evaluate the influence of intravenous contrast agent on the diagnostic ability for osteoporosis using CT attenuation measurement in patients with liver cirrhosis. This retrospective study was approved by our institutional review board and informed consent was waived. 208 patients with liver cirrhosis (mean age, 61.25 years ± 9.43 [standard deviation]; range, 30-82 years) who underwent both unenhanced and two contrast-enhanced (arterial and venous phase) abdominal dual-energy CT examinations from January 1 to September 1, 2020, were recruited. CT attenuation values were measured in the medullary compartment of vertebral body (L1-L3) and bone mass was determined by the hydroxyapatite concentration obtained in dual-energy spectral CT and used as the reference standard. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic ability of using CT attenuation number in unenhanced, arterial, and venous phases. Area under ROC curve using unenhanced CT attenuation was different from using arterial CT attenuation (p= 0.038) and venous CT attenuation (p = 0.048) to diagnosing osteoporosis. However, there was no significant difference between unenhanced CT attenuation and arterial CT attenuation (p = 0.773) and between unenhanced CT attenuation and venous CT attenuation (p = 0.746) to distinguish low bone mass (osteoporosis or osteopenia). The diagnostic ability for osteoporosis using CT attenuation measurement in contrast-enhanced scans is decreased due to intravenous contrast contamination, however, which had no influence on the diagnostic ability of CT attenuation for low bone mass (osteoporosis or osteopenia). The diagnostic ability of using enhanced CT attenuation values for osteoporosis decreased compared to unenhanced CT attenuation values.

3D Bioprinted GelMA-Gelatin-Hydroxyapatite Osteoblast Laden Composite Hydrogels for Bone Tissue Engineering.

Introduction 3D bioprinting offers a novel solution to critical sized bone defects by allowing the placement of osteogenic cells, additive biomaterials and bioactive signaling that mimic native tissue. We describe the suitability of an extrusion-based 3D bioink composed of gelatin methacryloyl (GelMA), gelatin, hydroxyapatite (HA), and osteoblasts for bone tissue engineering. Methods A mouse calvarial osteoblast-laden GelMA-gelatin-LAP bioink consisting of various concentrations of HA was 3D-bioprinted into a porous hydrogel construct. After days 1, 14, and 28, five constructs from each HA concentration were analyzed. The water weight percent differences of the hydrogels and the degradation behavior in enzyme solution were characterized. An ALP assay and histological analysis were performed. Cell survivability was determined using a LIVE/DEAD Viability/Cytoxicity Kit and AlamarBlue Cell Viability reagent. Real-time polymerase chain reaction (RT-qPCR) was performed to measure expression levels of bone morphogenetic protein-7 (BMP-7) and Osteocalcin (BGLAP). Results The addition of 5, 10, and 20 mg/ml of HA significantly reduced hydrogel swelling (p ≤ 0.01) from baseline GelMA-Gelatin hydrogels (Figure 3A). HA significantly decreased hydrogel breakdown in a concentration dependent manner (Figure 3B, p ≤ 0.001). A significant increase in cell proliferation at day 28 was noted in all groups (Figure 3D). ALP activity (Figure 3E) significantly increased with the addition of 5mg/ml and 20mg/ml of HA at days 7 and 28 (p ≤ 0.05). Live/dead staining at 1, 14, and 28 days showed high chondrocyte viability. The addition of 20mg/ml of HA demonstrated significantly greater BMP7 and BGLAP gene expression at both 14 and 28 days over the hydrogels without HA (Figure 5, p ≤ 0.05). Conclusion The addition of HA to GelMA-gelatin hydrogels significantly decreased hydrogel swelling, improved the ability of the hydrogel to resist enzymatic degradation, increased osteoblastic differentiation and mineralization, and increased osteogenic gene expression while maintaining equal cell viability and proliferation to non-HA hydrogels.

Anhydrous Proton Conductivity in HAp-Collagen Composite

It is well known that a proton conductor is needed as an electrolyte of hydrogen fuel cells, which are attracting attention as an environmentally friendly next-generation device. In particular, anhydrous proton-conducting electrolytes are highly desired because of their advantages, such as high catalytic efficiency and the ability to operate at high temperatures, which will lead to the further development of fuel cells. In this study, we have investigated the proton-conducting properties of the hydroxyapatite (HAp)-collagen composite without external humidification conditions. It was found that, by injecting HAp into collagen, the electrical conductivity becomes higher than that of the HAp or the collagen. Moreover, the motional narrowing of the proton NMR line is observed above 130 °C. These results indicate that the electrical conductivity observed in the HAp-collagen composite is caused by mobile protons. Furthermore, we measured the proton conduction of HAp-collagen composite films with different HAp contents and investigated the necessity of the appearance of proton conductivity in HAp-collagen composites. HAp content (n = 0–0.38) is the number of HAp per collagen peptide representing Gly-Pro-Hyp. These results indicate that injection of HAp into collagen decreases the activation energy of proton conduction which becomes almost constant above a HAp content n of 0.3. It is deduced that the proton-conduction pathway in the HAp-collagen composite is fully formed above n = 0.3. Furthermore, these results indicate that the value of the activation energy of proton conductivity was lowered, accompanied by the formation of the HAp-collagen composite, and saturated at n > 0.3. From these results, the HAp-collagen composite forms the proton-conduction pathway n > 0.3 and becomes the proton conductor with no external humidification in the condition of n > 0.3 above 130 °C.

Use of thermogravimetric analysis to estimate collagen and hydroxyapatite contents in archaeological bone

In this study, we evaluate whether thermogravimetric analysis (TGA) can be used to estimate the amounts of collagen and hydroxyapatite in archaeological bone accurately and rapidly, through evaluation of twenty-four previously analyzed archaeological human bone samples. Mass losses in the approximate ranges of 300–500 °C, 220–600 °C, and 600–900 °C, correspond to collagen mass loss, total organic mass loss, and hydroxyapatite mass loss, respectively. The first two mass losses (300–500 °C and 220–600 °C) show strong correlations with independently determined collagen content; however, the correlation between the third loss range (600–900 °C) and hydroxyapatite content was poor. Thus, TGA appears to be a good technique for estimating collagen but not apatite content in archaeological bone. As thermogravimetric analysis requires small amounts of material (tens of mg) and minimal sample preparation, while avoiding the superficiality of other collagen quantification methods (e.g., vibrational spectroscopy), it appears to be a promising technique for further archaeological exploration.

Exploring MgO/HA ceramic nano-composites for biodegradable implants: Exploring biological properties and micromechanics

The release of Mg ions from Mg-based implants during biodegradation can promote bone repair through osteoblast migration. However, the high pH values (alkaline stresses) associated with this process can be harmful for osteoblasts. Therefore, surface modifications are required which allow to adjust the Mg ion concentration within a tolerable range. The present work investigates the effect of anodizing of magnesium/hydroxyapatite metal matrix nano composites (Mg/HA-ncomposites) on micromechanical behavior and on biological properties. The results will be implemented into a design strategy for improved Mg/HA-ncomposites. The HIPed Mg/HA-ncomposites with varied content of nano hydroxyapatite (n-HA) particles (0, 0.75, 1.8, and 3 wt%) were anodized in a 6 M KOH solution at 1.50 V and 50 °C for 2 h to develop magnesium oxide/hydroxyapatite surface ceramic matrix nano-composite (MgO/HA-ncomposite). The specimens were evaluated by immersing the materials into simulated body fluid (SBF), seeding of human mesenchymal stem cells on the surfaces, and performing nano-indentation and nano-scratch tests. The results show that the uniform distribution of 1.8 wt% n-HA particles in the MgO converted layer strengthens its adhesion as compared to the other types of MgO/HA-ncomposites. Furthermore, the cell spreading of human mesenchymal stem cells on the composite of 1.8 wt% n-HA improves after the anodizing process and after a one-day cell culture. In summary, the present combined micromechanical and biological study has shown that the MgO/HA-ncomposite of 1.8 wt% n-HA represents a promising biomaterial for bio-absorbable bone implants and that it outperforms pure Mg-surfaces.

Tailorable 3DP Flexible Scaffolds with Porosification of Filaments Facilitate Cell Ingrowth and Biomineralized Deposition.

Facilitating cell ingrowth and biomineralized deposition inside filaments of 3DP scaffolds are an ideal bone repair strategy. Here, 3D printed PLGA/HA scaffolds with hydroxyapatite content of 50% (P5H5) and 70% (P3H7) were prepared by optimizing 3D printing inks, which exhibited good tailorability and foldability to meet clinical maneuverability. The supercritical CO2 foaming technology further endowed the filaments of P5H5 with a richer interconnected pore structure (P5H5-C). The finite element and computational fluid dynamics simulation analysis indicated that the porosification could effectively reduce the stress concentration at the filament junction and improved the overall permeability of the scaffold. The results of in vitro experiments confirmed that P5H5-C promoted the adsorption of proteins on the surface and inside of filaments, accelerated the release of Ca and P ions, and significantly upregulated osteogenesis (Col I, ALP, and OPN)- and angiogenesis (VEGF)-related gene expression. Subcutaneous ectopic osteogenesis experiments in nude mice further verified that P5H5-C facilitated cell growth inside filaments and biomineralized deposition, as well as significantly upregulated the expression of osteogenesis- and angiogenesis-related genes (Col I, ALP, OCN, and VEGF) and protein secretion (ALP, RUNX2, and VEGF). The porosification of filaments by supercritical CO2 foaming provided a new strategy for accelerating osteogenesis of 3DP implants.

Electrospun hydroxyapatite loaded L-polylactic acid aligned nanofibrous membrane patch for rotator cuff repair

Rotator cuff repair remains a challenge clinically due to the high retear rate after surgical intervention. There is a significant need to develop functional biomaterials facilitating tendon-to-bone integration. In this study, hydroxyapatite (HA) incorporated polylactic acid (PLLA) aligned nanofibrous membranes were fabricated by electrospinning as a low-cost sustainable rotator cuff patch. The morphology, physical, mechanical and in vitro cell assays of the nanofibrous membranes were characterized. The results showed that the nanofibrous membrane maintained a rough surface and weakened hydrophobicity. It has excellent cytocompatibility, and the cells were oriented along the direction of fiber arrangement. What's more, the PLLA-HA nanofibrous membrane could increase the alkaline phosphatase (ALP) expression in rat bone marrow mesenchymal stem cells (BMSCs), indicating that the electrospinning PLLA-HA nanofibrous membrane can better induce the bone formation of rat BMSCs cells. When the mass ratio of PLLA to HA exceeds 3: 1, with the increase of the HA content, the patch showed rising induction ability. The results suggested that electrospinning PLLA-HA nanofibrous membranes are an ideal patch for promoting tendon-bone healing and reducing the secondary tear rate. Furthermore, the use of biodegradable polymers and low-cost preparation methods presented the possibility for commercial production of these nanofibrous membranes.

Synthesis and Characterization of Hydroxyapatite Gel – Nanosilver – Clove Flower Extract (Syzygium Aromaticum L.) as a Toothpaste Forming Gel

Dental caries is a disease caused by the bacteria Streptococcus mutans and Lactobacillus, and affects everyone regardless of age. One way to overcome dental caries is to clean the teeth with a toothpaste made from hydroxyapatite-nano silver-clove extract. Hydroxyapatite is a biomaterial that has biocompatibility, bioactivity, and osteoconductive so that it can remineralize teeth. Nano silver is an antibacterial component that is able to kill microorganisms that cause dental caries. The addition of clove extract as an antimicrobial and aromatic compound can increase the attractiveness of the product. This study aims to determine the physical and chemical characteristics of the hydroxyapatite-nano silver-clove extract gel formulation with varying concentrations of hydroxyapatite 1%, 2%, and 3%, and nano silver concentrations of 1 ppm, 5 ppm, and 10 ppm. The results of the homogeneity test, pH level, dispersion, and adhesion showed that the gel was in accordance with the test standard. The results of organoleptic tests and statistical analysis showed that variations in the concentration of hydroxyapatite and nano silver affected the color and aroma (P < 0.05), but did not affect the texture (P > 0.05) of the gel. FTIR spectrophotometric analysis showed that the formulation already contained OH, CO32-, PO43- groups derived from hydroxyapatite, C=O derived from nano silver, and OCH, CH3, C-C, =C-H derived from clove extract.

Improved mechanical and microstructural performance of high-density polyethylene–chitosan–hydroxyapatite composites as potential bone implant materials

High-density polyethylene (HDPE)–chitosan–hydroxyapatite hybrid composite series with varying concentration of hydroxyapatite were prepared and compared with its corresponding HDPE-chitosan binary composite. The microstructural and mechanical characterizations of the prepared composites were studied. A 12% increase for the composite system with 8 wt% hydroxyapatite (HA4) has been noted when compared with its corresponding binary system and has been optimized for further applications. The structural characterization and miscibility of the components in the composite system were studied by using Fourier transform infrared spectroscopy and X-ray diffractometry. Positron annihilation lifetime spectroscopy studies showed that the free holes are formed in the range of ∼115.8 Å3. Contact angle studies and sorption studies were further correlated with the biocompatibility analysis to study cell adhesion and protein absorption on the surface of the composites. MC3T3 E1 cell lines showed good cell proliferation on the optimized systems. The presence of micropores along with chitosan and hydroxyapatite promoted cell growth in the prepared composites. The current research study presents the development of an improved hybrid biocomposite material that has potential in biomedical implants.

Enhancing structural strength and improving cell survival through Polycaprolactone/(gelatin/hydroxyapatite) Core‐Shell nanofibers for tissue engineering

AbstractBone tissue engineering is a practical approach to repairing broken or damaged bones that combines scaffold, cells, and growth factors for treatment. In this study, polycaprolactone (PCL)/gelatin (Ge)/hydroxyapatite (HA) core‐shell nanocomposites have been produced by the coaxial electrospinning method. Coaxial electrospinning is an efficient method for scaffold preparation to provide an interconnected porous fibrous scaffold. The prepared nanocomposite simultaneously benefited from the good mechanical behavior of the core PCL polymer. The desired biological properties also originated from the outer layer of the Ge/HA nanocomposite. Nanofibrous scaffolds' properties were characterized using SEM, TEM, FTIR, TGA, DSC, tensile test, contact angle, and MTT assay. The morphology of the as‐electrospun nanofibers was investigated using SEM and TEM, which revealed a defect‐less fibrous morphology. TEM images showed the core‐shell structure of the prepared scaffold nanofibers. The contact angle test showed that the presence of HA nanoparticles has improved the wettability of fibrous composites. In addition, HA nanoparticles could effectively strengthen the polymer scaffolds. The highest UTS value of 4.1 MPa was obtained in the PCL/(Ge+10%HA) sample. The cytotoxicity results revealed that the prepared scaffolds were utterly biocompatible. Moreover, significant cell proliferation of osteosarcoma cells was observed at high HA contents. The interconnected pores allowed cells to migrate into the scaffolds and grow inside. Based on the obtained results, PCL/(Ge/ HA) core‐shell nanofibers could be a promising candidate for bone scaffolds.

Evaluation of carbon nanotubes-hydroxyapatite nanocomposites as bioactive implant coats radiated by near infrared laser.

This study aimed to evaluate carbon nanotubes-hydroxyapatite nanocomposites as bioactive titanium implant coats and to assess the effect of near-infrared radiation on these nanocomposites. Carbon nanotubes were acid-functionalized, and hydroxyapatite was prepared by the wet-chemical precipitation method. Both precursors were used to prepare the carbon nanotubes-hydroxyapatite nanocomposites in two concentrations of hydroxyapatite (0.5 and 1 wt.%). The formed nanocomposites were characterized and used to coat silanized titanium discs and cylinders. Half the specimens of each group were radiated by near-infrared laser, then wettability and shear bond strength were tested for all specimens. Bioactivity was tested by monitoring the formation of calcium phosphate compounds after soaking in simulated body fluid. A significant increase in wettability and bond strength was found in the radiated coats compared to the non-radiated ones with the 1% hydroxyapatite group showing the highest values followed by 0.5% hydroxyapatite then the carbon nanotubes group. The two-way ANOVA test showed that both the difference in material and the laser treatment have had a statistically significant contribution to the increase in wettability and bond strength. The radiated groups also contributed to the formation of more calcium phosphate crystals of larger sizes and higher degrees of crystallinity.

Effects of hydroxyapatite addition on corrosion behavior and in-vitro bioactivity of Ti-10Mo matrix biocomposite

Ti-10Mo/HA (hydroxyapatite) biocomposites were prepared by powder metallurgy. The electrochemical corrosion behavior and in-vitro bioactivity were investigated in this study. After addition of HA, the results of the electrochemical tests show that the corrosion resistance of the composites decrease. The non-uniform distribution of β phase region (Mo rich) and partition effect of pores lead to the inhomogeneity and discontinuity of oxide films on the surface of titanium alloy matrix. The introduction of O and incomplete diffusion of Mo make much more α-Ti reserved, which is inferior to β-Ti in terms of the corrosion resistance. Besides, the large and interconnected pores in the composites may cause the crevice corrosion. With addition of HA, the increased ceramic phases and micropores improve the bioactivity obviously. After soaking in SBF for 7 d, a lot of spherical apatite was deposited on the surface of Ti-10Mo/HA composite, while the modified Ti-10Mo alloy was partially covered by several apatite particles. The ceramic phases and micropores enhance the surface energy of the composites, and the wettability is improved, which is conducive to apatite deposition and cell adhesion, but unfavorable to the corrosion resistance. So that the HA content should be controlled in a reasonable range according to the performance requirements of the composites.