Amount Of Hydroxyapatite Research Articles

Corrosion Behavior and Biological Properties of ZK60/HA Composites Prepared by Laser Powder Bed Fusion.

Magnesium alloy ZK60 shows great promise as a medical metal material, but its corrosion resistance in the body is inadequate. Hydroxyapatite (HA), the primary inorganic component of human and animal bones, can form chemical bonds with body tissues at the interface, promoting the deposition of phosphorus products and creating a dense calcium and phosphorus layer. To enhance the properties of ZK60, HA was added to create HA/ZK60 composite materials. These composites, fabricated using the advanced technique of LPBF, demonstrated superior corrosion resistance and enhanced bone inductive capabilities compared to pristine ZK60. Notably, the incorporation of 3 wt% led to a significant reduction in bulk porosity, achieving a value of 0.8%. The Ecorr value increased from -1.38 V to -1.32 V, while the minimum Icorr value recorded at 33.9 μA·cm-2. Nano-HA achieved the lowest volumetric porosity and optimal corrosion resistance. Additionally, these composites significantly promoted osteogenic differentiation in bone marrow stromal cells (BMSCs), as evidenced by increased alkaline phosphatase (ALP) activity and robust calcium nodule formation, highlighting their excellent biocompatibility and osteo-inductive potential. However, when increasing the HA content to 6 wt%, the bulk porosity rose significantly to 3.3%. The Ecorr value was -1.3 V, with the Icorr value being approximately 50 μA·cm-2. This increase in porosity and weaker interfacial bonding, ultimately accelerated electrochemical corrosion. Therefore, a carefully balanced amount of HA significantly enhances the performance of the ZK60 magnesium alloy, while excessive amounts can be detrimental.

Study on distribution of hydroxyapatite (HA) in twin screw extruded cum injection moulded polylactic acid (PLA) composites and their effect on mechanical property

Hydroxyapatite (HA) reinforced polylactic acid (PLA) composite is the most investigated material for biodegradable implant applications such as screws and plates. The objective of this work is to test hypothesis of distribution of HA in PLA composite influence on the variations in the properties of the composites. Investigation was done for the distribution of HA in PLA injection mould (IM) composites for the various concentrations (2 to 8 wt.%) and their effect on mechanical properties such as flexural and tensile test. Proportionate quantity of HA was introduced at fixed intervals in a twin screw extruder for the preparation of PLA composites pellets containing in various wt.% of HA. The distribution of HA in IM PLA composite specimens was analysed by elemental mapping using scanning electron microscope (SEM) and also by estimation of residue (HA) after burn out test of sampling of specimens. Differential scanning calorimetry (DSC) was used for the study of effect of HA in PLA composites. The value of standard deviations of mechanical properties, taken as a rudimentary measure of reliability of IM PLA-HA composites, was found to have influence from the distributions of HA. Among the composites studied, PLA-HA composite with 4 and 5 HA wt.% found exhibiting reliable mechanical property due to crystallinity of 31.83% and a comparatively better homogenous dispersion of HA in PLA. A case study of distribution of HA in a product, namely, bone screw, promulgated the issues of IM PLA-HA composites for biomedical applications.

Effect of pH on hydroxyapatite coatings obtained by spray pyrolysis and their use as matrices for antibiotic adsorption by spin coating and release properties.

Calcium phosphate materials, particularly hydroxyapatite (HA), are extensively used in biomedical applications because of their prominence as primary inorganic constituents of human hard tissues. This study investigates the synthesis of HA coatings via spray pyrolysis using various precursors, including HA derived from bovine bone. The effects of pH on the formation and properties of HA coatings were systematically examined. Samples exposed to acidic conditions or left without pH adjustment led to the formation of HA, contrasting with the outcomes observed through dissolution methods. Different characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), were employed to evaluate the quality and crystallinity of the coatings. Among the samples, those exhibiting superior crystallinity and nanostructured features, including bovine HA, were selected for further surface functionalization with the antibiotic enrofloxacin using spin coating. As expected, the antibiotic loading on each material's surface depended on the amount of HA deposited on the substrate. However, the desorption results indicated that, in all cases, desorption persisted beyond 38 h, implying that HA-loaded matrices could be effective systems for controlled and prolonged drug release, which could be useful in dental or orthopedic implants for inhibiting the growth of bacterial biofilms.

The Impact of Titanium Hydroxyapatite Doping on the Mechanical and Biological Properties of Photocured Resin.

Photocured resin materials are widely used in various fields, such as 3D printing, medical applications, and dentistry. However, the strength, wear resistance, and antibacterial properties of photocured resin are relatively limited, rendering it susceptible to potential failures. In this recent study, photocured composite resins incorporating titanium-doped hydroxyapatite (Ti-HAp) were fabricated to investigate their mechanical and biological properties. It was found that the hardness and wear resistance increased with the addition of an appropriate amount of hydroxyapatite (HAp). Specifically, the 6wt%HAp resin demonstrated superior hardness. Compared with the 6wt%HAp resin, the acid resistance and wear resistance improved when an appropriate amount of Ti-HAp was added. Notably, the resin containing 0.56%Ti-HAp demonstrated superior wear resistance. Additionally, the antibacterial performance improved with higher titanium (Ti) content, showcasing a 71.9% improvement in the resin containing 1.37%Ti-HAp compared with the 6wt%HAp resin, alongside commendable remineralization capabilities. In summary, the Ti-HAp composite resin showed enhanced mechanical and biological properties, meeting clinical standards in terms of mechanical and antibacterial properties.

Hydroxyapatite-Filled Acrylonitrile-Butadiene Rubber Composites with Improved Cure Characteristics and Reduced Flammability.

The goal of this work was to develop acrylonitrile-butadiene (NBR) elastomer composites filled with hydroxyapatite (HAP) characterized by improved cure characteristics and resistance to burning. Silane, i.e., (3-aminopropyl)-triethoxysilane, ionic liquid, i.e., 1-decyl-3-methylimidazolium bromide and surfactant, i.e., cetyltrimethylammonium bromide, were used to improve the filler's dispersibility in the elastomer matrix and to reduce the time and temperature of vulcanization. The effects of HAP and dispersants on the cure characteristics, crosslink density and physico-chemical properties of NBR composites were explored. The additives used, especially the ionic liquid and surfactant, effectively improved the dispersion of HAP in the NBR matrix. The amount of HAP and the dispersant used strongly affected the cure characteristics and crosslink density of NBR. The optimal vulcanization time significantly increased with HAP content and was pronouncedly reduced when ionic liquid and surfactant were applied. In addition, ionic liquid and surfactant significantly lowered the onset vulcanization temperature and improved the crosslink density and hardness of the vulcanizates while impairing their elasticity. HAP and dispersants did not significantly affect the damping properties or chemical resistance of NBR vulcanizates. Above all, application of HAP considerably enhanced the resistance of vulcanizates to thermo-oxidative aging and reduced their flammability compared with the unfilled NBR.

Effect of PVDF, HA, and AgNO3 Annealing on β-Phase, Optical, and Mechanical Properties

Typically, polymer composites and ceramics are used to create biosensors. Materials with properties that are ideal for biosensors and chemical sensors include AgNO3 (silver nitrate), PVDF (polyvinylidene fluoride), and HA (hydroxyapatite). Polyvinylidene fluoride (PVDF) polymer has been widely used in several applications because of its well-known superior ferroelectric characteristics and biocompatibility. The brittleness and low bending strength of hydroxyapatite limit its applicability. Several HA and polymer composite formulations have been developed to compensate for HA’s mechanical weakness. The final product contains a significant amount of HA, making HA/polymer composites highly biocompatible. When the right amount of silver is deposited, the maximum piezoelectric activity is generated, and silver nitrate has antimicrobial properties. The non-toxic solvent DMSO (dimethyl sulfoxide) and the solvent casting method were chosen for the preparation of the film. Surface roughness was chosen to measure the Str and Sdr properties of the thin film. For liquid preparation, the multifractal spectra analysis was chosen for each sample. SEM was used to examine the samples morphologically. EDX and mapping analyses were presented for chemistry distribution in the samples.

New insights into defluoridation via induced crystallization: Implications of phosphate species regulation for process efficiency and economics

Excess fluoride (F) at low concentrations in groundwater remains a challenge. F removal via fluidized-bed induced crystallization has been receiving increasing attention; however, the precipitant cannot be fully utilized. This results in generation of by-products, inadvertently increases the treatment cost, and impedes the assessment of product purity. In this study, phosphate species regulation was employed to improve the F removal efficiency without decreasing the phosphate utilization efficiency. It shows that F concentration could be reduced from 4.75 to 0.45 mg·L−1, with P concentration in the effluent being only 0.05 mg·L−1 at a P:F molar ratio of 3, involving appropriately mixed phosphate species. Hydroxyapatite (HAP) crystallization, subsequent F adsorption, and directly induced fluorapatite (FAP) crystallization occurred simultaneously in the fluidized bed, which was indirectly confirmed through intermittent operation of the process. The products of the induced crystallization process were FAP and a small amount of HAP, as determined qualitatively using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) tests. Overall, by regulating the phosphate species, the F removal efficiency is maintained, the cost of the precipitant is lowered, and the residual P concentration in the effluent is reduced. The process results in products with FAP as the main component, which can be used as raw material for the phosphoric acid purification process.

Antibacterial, mechanical, and dielectric properties of hydroxyapatite cordierite/zirconia porous nanocomposites for use in bone tissue engineering applications

Abstract We made nanocomposites with different amounts of hydroxyapatite (HA), cordierite (Cord), and zirconia (ZrO2), then sinterized them and studied them using X-ray diffraction (XRD) technique and field emission scanning electron microscopy (FESEM). Additionally, the bioactivity of the sintered samples was assessed in vitro following treatment with simulated bodily fluid (SBF), and FESEM was used to validate the creation of the HA layer on their surfaces. Measurements were also made for mechanical and antibacterial properties. All materials' electrical and dielectric characteristics were assessed before and after being treated with SBF solution. All of the samples that were studies had porosity increases of about 7.14, 22.44, 43.87, and 73.46%. This was because the sintering temperature was lowered while the concentration of ZrO2 in the samples increased. Also, the microhardness got 5.35, 14.28, 28.57, and 55.35% better because there was more ZrO2 and Cord in the samples than in the sample that did not have them. In addition, the compressive strength of all studied samples followed this trend, as it increased by 2.81, 7.79, 17.74, and 34.32% due to the reasons mentioned above. Furthermore, the electrical conductivity of the tested samples decreased as they increased their ZrO2 and Cord contents. The bioactivity of the research materials also somewhat decreased as the concentrations of Cord and ZrO2 were enhanced over time. Due to the magnesium (Mg2+) ions found in Cord's composition and the samples' porousness, which aided in forming an apatite layer on their surface, their bioactivity behavior was slightly reduced. All the samples that were looked at had a strong antibacterial effect on Staphylococcus epidermidis (S. epidermidis bacteria), which stopped their growth to a point between 2.33–3.30 mm. These results supported the notion that the generated porous nanocomposites have great potential for use in bone tissue engineering.

Fabrication and characterization of 3D-printed composite scaffolds of coral-derived hydroxyapatite nanoparticles/polycaprolactone/gelatin carrying doxorubicin for bone tissue engineering

In this study, nanocomposite scaffolds of hydroxyapatite (HA)/polycaprolactone (PCL)/gelatin (Gel) with varying amounts of HA (42–52 wt. %), PCL (42–52 wt. %), and Gel (6 wt. %) were 3D printed. Subsequently, a scaffold with optimal mechanical properties was utilized as a carrier for doxorubicin (DOX) in the treatment of bone cancer. For this purpose, HA nanoparticles were first synthesized by the hydrothermal conversion of Acropora coral and characterized by using different techniques. Also, a compression test was performed to investigate the mechanical properties of the fabricated scaffolds. The mineralization of the optimal scaffold was determined by immersing it in simulated body fluid (SBF) solution for 28 days, and the biocompatibility was investigated by seeding MG-63 osteoblast-like cells on it after 1–7 days. The obtained results showed that the average size of the synthesized HA particles was about 80 nm. The compressive modulus and strength of the scaffold with 47 wt. % HA was reported to be 0.29 GPa and 9.9 MPa, respectively, which was in the range of trabecular bones. In addition, the scaffold surface was entirely coated with an apatite layer after 28 days of soaking in SBF. Also, the efficiency and loading percentage of DOX were obtained as 30.8 and 1.6%, respectively. The drug release behavior was stable for 14 days. Cytotoxicity and adhesion evaluations showed that the fabricated scaffold had no negative effects on the viability of MG-63 cells and led to their proliferation during the investigated period. From these results, it can be concluded that the HA/PCL/Gel scaffold prepared in this study, in addition to its drug release capability, has good bioactivity, mechanical properties, and biocompatibility, and can be considered a suitable option for bone tumor treatment.Graphical

Solvent/non-solvent treatment as a method for surface coating of poly(ε-caprolactone) 3D-printed scaffolds with hydroxyapatite

Introduction Over the last decades numerous new materials and techniques for bone tissue engineering have been developed. The use of bioresorbable polymeric scaffolds is one of the most promising techniques for surgical management of bone defects. However, the lack of bioactive properties of biodegradable polymers restricts the area of their application for bone tissue engineering.The aim of study was to apply solvent/non-solvent treatment to coat the surface of 3D-printed bioresorbable poly(ε-caprolactone) scaffolds with bioactive hydroxyapatite particles and report on the physicochemical properties of the resulting materials.Material and Methods In the present study, biomimetic poly(ε-caprolactone) scaffolds were 3D-printed via fused deposition modeling technology and their surface was treated with the solvent/non-solvent method for coating with bioactive particles of hydroxyapatite.Results It has been found that treatment in the mixture of toluene and ethanol is suitable for the coating of poly(ε-caprolactone) scaffolds with hydroxyapatite. The scaffolds maintain porous structure after treatment while hydroxyapatite particles form homogeneous coating. The amount of hydroxyapatite on the treated scaffolds was 5.7 ± 0.8 wt. %.Discussion The proposed method ensures a homogeneous coating of outer and inner surfaces of the poly(ε-caprolactone) scaffolds with hydroxyapatite without a significant impact on the structure of a scaffold. Fourier-transform infrared spectroscopy confirmed that the solvent/non-solvent treatment has no effect on the chemical structure of PCL scaffolds.Conclusion Coating of biomimetic 3D-printed PCL scaffolds with bioactive hydroxyapatite by the solvent/non-solvent treatment has been successfully carried out. Upon coating, scaffolds retained their shape and interconnected porous structure and adsorbed hydroxyapatite particles that were uniformly distributed on the surface of the scaffold.

Effect of Bilayer Nano-Micro Hydroxyapatite on the Surface Characteristics of Implanted Ti-6Al-4V ELI

Ti-6Al-4V ELI is a well-known, popular medical-grade titanium alloy due to its biocompatibility and excellent mechanical properties. However, like other metal implants, it is less bioactive that affects tissue regeneration around the implant, and may lead to implant failure. So, a bioactive substance such as hydroxyapatite (HA) has usually been coated on metal implants to improve its bioactive properties. However, a single layer of HA was reported to be dissolved into body fluid after a long time of exposure in the human body. In this study, bilayer HA was deposited on the surface of screw-type implants made of Ti-6Al-4V ELI through electrophoretic deposition (EPD method. The bottom layer consists of micro-size of HA, and the second layer contains nano-size HA. The suspension contains each micro and nano size of HA powder was homogenized for 1 h followed by sonication for 2 h using a magnetic stirrer. The coating layer was subsequently sintered at 700oC for 1 h. The bilayer-coated screw implant was then implanted into the proximal tibia of health rattus novergicus under proper surgical procedures. Some screws without HA deposition were also implanted into rattus novergicus for comparison. The implanted screws were then taken out via surgery after 2, 3 and 4 weeks, and they were subsequently observed by optical microscope, SEM and XRF. The results showed that organic material is found on each coated specimen, and few HA layer is disintegrated from the surface of the screw. The disintegrated HA remained in the surface of the screw, and the amount of HA increased with increasing implantation time, which indicates the increase of osseointegration between the bone and HA layer. XRF showed a significant difference in Ti and titanium oxide contents on the surface of the coated samples and the non-coted ones, where it is only 0.66%Ti (0.39% TiO2) on the surface of the screw with HA layer and 70%Ti (67% TiO2) for without HA. When TiO2 is formed as a fast self-healing reaction while the screw is exposed to body fluid, the HA acts as an interface against body fluid that may contain aggressive ions. So, HA layer is not only effective against corrosion attack but also inhibits the formation of TiO2 on the implant surface. The coated screws also revealed a strong bonding between the HA layer and the surface of the implant screw. Besides, the ratio between Ca and P elements on the screw surface is in the range of 0.58 – 2.04, which is in the range of bone characteristics.

Restorative Dental Resin Functionalized with Calcium Methacrylate with a Hydroxyapatite Remineralization Capacity.

The ability of dental materials to induce the mineralization of enamel like hydroxyapatite (HA) is of great importance. In this article, a novel kind of dental restorative material characterized by a mineralization ability was fabricated by photopolymerization. Calcium methacrylate (CMA) was introduced into the classical bisphenol A-glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) dental resin formulation. This functional dental resin (BTCM) was calcium-rich and can be prepared simply by one-step photopolymerization. The influence of CMA on the photopolymerization kinetics, the dental resin's mechanical properties, and its capacity to induce dynamic in situ HA mineralization were examined. Real-time FTIR, compression modulus, scanning electron microscopy, X-ray spectroscopy, MTT assay, and cell attachment test were carried out. The obtained data were analyzed for statistical significance using analysis of variance (ANOVA). Double bond conversion could be completed in less than 300 s, while the compression modulus of BTCM decreased with the increase in CMA content (30 wt%, 40 wt%, and 50 wt%). After being soaked in Ca(NO3)2 and Na2HPO4 solutions alternatively, dense HA crystals were found on the surface of the dental resin which contained CMA. The amount of HA increased with the increase in CMA content. The MTT results indicated that BTCM possesses good biocompatibility, while the cell adhesion and proliferation investigation demonstrated that L929 cells can adhere and proliferate well on the surface of BTM. Thus, our approach provides a straightforward, cost-effective, and environmentally friendly solution that has the potential for immediate clinical use.

Effect of Nano-sized Hydroxyapatite Filler on Remineralization Efficacy of an Adhesive Resin: an in vitro study

Aim The aim of this study was to evaluate the remineralization efficacy of an adhesive resin containing nano-sized hydroxyapatite filler. Methodology The study consisted of four groups: control (without filler), 2% hydroxyapatite (HA), 5% HA, and 7% HA. Nano-hydroxyapatite powder was mixed with Scotchbond Multi-Purpose®. The teeth were sectioned to expose the midcoronal dentine. Bonding agents and resin composite restorations were applied. Teeth were incubated in simulated body fluid for 24-h, 30-day, and 90-day intervals. After incubation, the teeth were sliced. Hardness and elasticity modules were obtained for the three different time periods (for a total of n = 360 samples). The detection and measurement of mineral deposition areas were obtained by confocal laser scanning microscopy (CLSM) (for 120 samples). Elemental analysis was performed with energy-dispersive X-ray spectroscopy (EDS) (n = 360 samples). The statistical analysis of each parameter was performed using two-way ANOVA and group comparisons by post hoc tests. Results Study groups and storage periods affected the hardness (p = 0.00) and elasticity scores (p = 0.00). The CLSM results showed that increasing the storage periods and amount of HA resulted in mineral deposition areas (p = 0.02). The calcium and phosphor ion values of dentine that were obtained using EDS were increased (p = 0.00). Conclusion Hydroxyapatite fillers positively affect the remineralization activity of adhesive resins. In terms of remineralization efficacy, the best results were obtained in the 7% HA group.

Evading stability-biocompatibility tradeoff in TiNb coatings with armour-like super hydrophilic micro-nano structure surface

Modification of micro-nano structures on the surface of medical implants using a femtosecond laser (FSL) can improve cell behavior, increase tissue and material bonding strength, and promote preferred osseointegration. Nevertheless, the FSL processed micro-nano structures suffer from a compromise between biocompatibility and structural stability. Herein, a Ti32·5Nb alloy laser cladding (LC) coating was initially created on the surface of the Ti6Al4V (TC4) substrate, followed by the construction of an armour-like micro-nano structure with structural stability and biocompatibility on the coating surface. The results show that the microhardness, were resistance and corrosion resistance of the coatings were significantly improved. It efficiently prevents wear damage to the micro-nano structure by modifying the surface armour structure of FSL. In addition, a considerable quantity of hydroxyapatite (HA) is deposited on the surface, resulting in a Ca/P ratio that is closer to that of osteogenesis. Moreover, the surface structure is a periodic micro-nano structure with three-level distribution, which can guide the migration and proliferation of cell nanofiber matrix. Human osteosarcoma cells (MG-63) adhere to the surface and proliferate rapidly along the direction of the micro-nano structure. Hereby, the armoured micro-nano structures developed exhibit sustained wear resistance and great biocompatibility. It offers a wide range of applications in the field of surface modification of orthopedic biomaterials.

Characterization of PA12/HA composite scaffolds based on selective laser sintering

Composite scaffolds have been extensively studied in bone tissue engineering, which can achieve excellent properties that cannot be obtained by a single material. In this study, the effect of hydroxyapatite (HA) on the reliability of polyamide 12 (PA12) scaffold for bone graft was explored in terms of mechanical and biological properties. Thermal properties testing showed that no physical or chemical reaction occurs in the prepared PA12/HA composite powders. Further, compression experiments showed that adding a small amount of HA promoted the mechanical properties of the scaffold, while excessive HA results in agglomeration and impairs the PA12/HA scaffold. For the scaffolds with the porosity of 65%, the 96% PA12/4% HA scaffold has a 7.3% higher yield strength and a 13.5% higher compressive modulus than the pure PA12 scaffold while the strength of the 88% PA12/12% HA scaffold decreases by 35.6%. Furthermore, contact angle and CCK-8 tests confirmed that 96% PA12/4% HA scaffold effectively improved the hydrophilicity and biocompatibility of the scaffold. Its OD value on the 7th day is 0.949, which is significantly higher than that of other groups. In summary, PA12/HA composites have good mechanical properties and biocompatibility, which can be used as an effective strategy in bone tissue engineering.

REAL-TIME ASSESSMENT OF THE OSTEOGENIC POTENTIAL OF HMSCS BY 99MTC-HDP-LABELLING DURING AN ONGOING CELL CULTURE

The novel, highly-sensitive and non-destructive method for the quantification of the osteogenic potential of bone marrow mesenchymal stem cells (BM-MSCs), by the evaluation of its hydroxyapatite (HA), in vitro is 99mTc-HDP-Labelling. 99mTc-HDP (tracer) binds rapidly to HA and this uptake can be visualized and quantified. This study was performed to evaluate if this method is suitable to perform a real-time assessment during an ongoing cell culture and if the radioactive tracer may influence the cells and their ability to differentiate.BM-MSCs (n=3) were cultivated in 35mm-dishes. Groups 1 and 3 received DMEM-LG based osteogenic media while Groups 2 und 4 were non-osteogenic controls.Groups 1 and 2 (multi-labelling) were incubated with 5 MBq 99mTc-HDP for 30min on day 7 (d7) and the bound activity was measured using an activimeter. Subsequently the cell-culture was continued and again labelled with 99mTc-HDP on day 14 and 21 (d14, d21).Groups 3 and 4 (single labelling), cultivation of the respective triplicates, ended on day 7, 14 and 21 (d7, d14, d21) followed by 99mTc-HDP-Labelling.Statistical analysis using one-factor ANOVA (p<0.05).Absolute tracer uptake increased steadily in both osteogenic groups: 1 (d7: 0.315; d14: 1.093; d21: 3.283 MBq) and 3 (d7: 0.208; d14: 0.822; d: 212.437 MBq) and was significantly higher than in the corresponding non-osteogenic control-group (Group 2 and 4) at all timepoints. (p<0.001).No significant negative effect of the radioactive tracer could be revealed in group 1 (multi radioactive labelling on d7, d14, d21) compared to Group 3 (singe labelling).The 99mTc-Uptake of groups 2 and 4 was not significantly different at any time.Our data show that the repeated exposition to 99mTc-HDP has no negative influence on the osteogenic differentiation potential of BM-MSCs. Therefore, the method is capable of determining the amount of HA during an ongoing cell culture.

Preparation, Characterization, and Biological Properties of Hydroxyapatite from Bigeye Snapper (Priancanthus tayenus) Bone.

The optimum condition of acid hydrolysis for hydroxyapatite extraction from bigeye snapper (Priancanthus tayenus) bone and the effects of extraction time (10-60 min) and HCl concentration (2.0-5.0% w/v) on yield and hydroxyapatite properties were determined. The optimum extracted condition was found using 5% HCl for 60 min, which was 13.4% yield; 19.8 g/100 g Ca content; 9.6 g/100 g P content; 2.1 Ca/P ratio; L*, a*, b*; and ΔE as 84.5, 2.8, 16.5, and 15.6, respectively. The using of 5% NaOH solution was optimum for hydroxyapatite precipitation from the extracted solution. The characteristic and biological properties of the obtained hydroxyapatite were studied. Fourier transform infrared spectroscopy and X-ray diffraction results showed a good comparison between the extracted and commercial hydroxyapatite. The microstructure of the extracted hydroxyapatite from a scanning electron microscope showed an irregular and flat-plate shape, large surface area, and roughness. The extracted hydroxyapatite was non- and low-cytotoxicity at a concentration of 50 and 100-400 µg/mL, respectively. Bovine serum albumin (BSA) adsorption and desorption of hydroxyapatite was studied. An increasing BSA concentration, hydroxyapatite amount, and adsorption time significantly increased protein adsorption on hydroxyapatite. Protein desorption from BSA-loaded hydroxyapatite showed an increase of release initially in the first 4 days and became a steady release rate until 14 days.

A Novel Chitosan Composite Biomaterial with Drug Eluting Capacity for Maxillary Bone Regeneration.

Bone grafting is one of the most commonly performed treatments for bone healing or repair. Autografts, grafts from the same patient, are the most frequently used bone grafts because they can provide osteogenic cells and growth factors at the site of the implant with reduced risk of rejection or transfer of diseases. Nevertheless, this type of graft presents some drawbacks, such as pain, risk of infection, and limited availability. For this reason, synthetic bone grafts are among the main proposals in regenerative medicine. This branch of medicine is based on the development of new biomaterials with the goal of increasing bone healing capacity and, more specifically in dentistry, they aim at simultaneously preventing or eliminating bacterial infections. The use of fibers made of chitosan (CS) and hydroxyapatite (HA) loaded with an antibiotic (doxycycline, DX) and fabricated with the help of an injection pump is presented as a new strategy for improving maxillary bone regeneration. In vitro characterization of the DX controlled released from the fibers was quantified after mixing different amounts of HA (10-75%). The 1% CS concentration was stable, easy to manipulate and exhibited adequate cuttability and pH parameters. The hydroxyapatite concentration dictated the combined fast and controlled release profile of CSHA50DX. Our findings demonstrate that the CS-HA-DX complex may be a promising candidate graft material for enhancing bone tissue regeneration in dental clinical practice.

Highly stretchable hydroxyapatite bionanocomposite for high-performance triboelectric nanogenerators.

Renewable energy has been a focus in recent years. Triboelectric nanogenerators (TENGs) have potential for converting mechanical energy into electricity. However, there are restrictions on the use of biological materials and bionanocomposites, such as the high cost and complexity of the synthesis process, poor stability, and inadequate output performance. To overcome the constraints of TENGs, we have turned to hydroxyapatite, a biological substance with great biocompatibility and high mechanical strength that can be manufactured from waste materials. We successfully developed a negative triboelectric bionanocomposite hydroxyapatite (HA) loaded polydimethylsiloxane (PDMS) to harness energy from biomechanical sources such as wearable devices. A TENG (2 × 2 cm2) with a pushing force of 2 N and different amounts of HA in PDMS can produce highly stable output voltage, current, surface charge density, and power density values of 300 V, 22.4 μA, 90.36 μC m-2, and 27.34 W m-2, which are 6, 9, and 10 times higher than those without HA, respectively. These improvements were attributed to the highest observed surface potential of 1512 mV. After 20 000 cycles of contact-separation, the HA/PDMS-TENG shows exceptionally stable performance. Furthermore, adding HA improves the mechanical properties and the stretchability of the bionanocomposite. The HA/PDMS bionanocomposite exhibits remarkable stretchability of more than 290%. Effectively harvesting energy from body movements, the TENG gadget may be used to charge multiple commercial capacitors, drive up to 100 LEDs, and power a low-power electronic device. Self-powered sensing and wearable devices are made possible by the HA/PDMS-TENG, which allows their large-scale preparation and deployment.

Evaluation of the Effect of the Addition of Hydroxyapatite on Selected Mechanical and Tribological Properties of a Flow-Type Composite.

(1) Background: The aim of the study was to determine the effect of modification with sintered hydroxyapatite (HAp) on selected mechanical and tribological properties of a flow-type composite. (2) Methods: Samples in the shapes of cuboidal beams (n = 120) and cylinders (n = 120) with the proper dimensions were prepared from a standard flow-type composite and others with the addition of 2% wt., 5% wt., and 8% wt. sintered hydroxyapatite. The bending strength, compression strength, diametral compression strength, impact resistance, hardness, and tribological properties were compared. (3) Results: In all cases, it was established that an increase in the amount of HAp caused a reduction in the bending, compression, and diametral compression strength. Increasing the amount of added HAp also reduced the impact strength, hardness, and wear resistance. However, the differences were statistically insignificant. (4) Conclusions: The addition of hydroxyapatite to a flow-type composite material worsened its mechanical and tribological properties; however, the obtained values were acceptable with 2% wt. and 5% wt. HAp.