Hydroxyapatite Powder Research Articles

Study of Polysulfone-Impregnated Hydroxyapatite for Ultrafiltration in Whey Protein Separation.

Polysulfone (Psf) ultrafiltration flat-sheet membranes were modified with hydroxyapatite (HA) powder during preparation using the wet-phase inversion method. HA was incorporated to enhance the protein separation capabilities. The asymmetric Psf membranes were synthesized using NMP as the solvent. Through Scanning Electron Microscopy (SEM) analysis, it was revealed that HA was distributed across the membrane. Incorporating HA led to higher flux, the improved rejection of protein, and enhanced surface hydrophilicity. The permeability flux increased with HA concentration, peaking at 0.3 wt.%, resulting in a 38% improvement to 65 LMH/bar. Whey protein separation was evaluated using the model proteins BSA and lysozyme, representing α-Lactalbumin. The results of protein rejection for the blend membranes indicated that the rejection rates for BSA and lysozyme increased to 97.2% and 73%, respectively. Both the native and blend membranes showed similar BSA rejection rates; however, the blend membranes demonstrated better performance in lysozyme separation, indicating superior selectivity compared to native membranes. The modified membranes exhibited improved hydrophilicity, with water contact angles decreasing from 66° to 53°, alongside improved antifouling properties, indicated by a lower flux decline ratio value. This simple and economical modification method enhances permeability without sacrificing separation efficiency, hence facilitating the scalability of membrane production in the whey protein separation industry.

Application of Waste Bovine Bone-derived Hydroxyapatite to Biodegradable Coatings for Paper-based Food Packaging

Hydroxyapatite (HAp) powder was produced by utilizing food waste bovine bones through alkaline treatment and calcination. The biodegradable coatings on paper-based food packaging that contained synthesized HAp were subsequently prepared and characterized. The slurry of 5 wt% of bovine bones synthesized HAp, 2 wt% of polyvinyl alcohol, and glycerol was coated on a grey back duplex board (GB) by dipping and spraying. The morphology, color, penetration strength, water and oil absorption, and biodegradability of the coated GB were observed. The color of the spray-coated GB was still slightly brighter (L*) than others due to its good coating ability before and after being heated at 800 W in a microwave oven for 1 minute. The penetration strength of coated GB was higher than that of noncoated GB after containing hot water. The coated GB had 8% water absorption, which was lower than that of the noncoated GB (10%), while oil absorption was nearly the same (3%). Moreover, the biodegradable properties of both coated GBs were not significantly different compared to the non-coated samples.

On the Role of Substrate in Hydroxyapatite Coating Formation by Cold Spray

The deposition of agglomerated hydroxyapatite (HAp) powders by low-pressure cold spray has been a topic of interest in recent years. Key parameters influencing the deposition of HAp powders include particle morphology and impact kinetic energy. This work examines the deposition of HAp powders on various metal surfaces to assess the impact of substrate properties on the formation of HAp deposits via cold spray. The substrates studied here encompass metals with varying hardness and thermal conductivities, including Al6061, Inconel alloy 625, AISI 316 stainless steel, H13 tool steel, Ti6Al4V, and AZ31 alloy. Single-track experiments offer insights into the initial interactions between HAp particles and different substrate surfaces. In this study, the results indicate that the ductility of the substrate may enhance HAp particle deposition only at the first deposition stages where substrate/particle interaction is the most critical factor for deposition. Features on the substrate associated with the first deposition sprayed layer include localized substrate deformation and the formation of clusters of HAp agglomerates, which aid in HAp deposition. Furthermore, after multiple spraying passes on the various metallic surfaces, deposition efficiency was significantly reduced when the build-up process of HAp coatings shifted from ceramic/metal to ceramic/ceramic interactions. Overall, this study achieved agglomerated HAp deposits with high deposition efficiencies (30–60%) through single-track experiments and resulted in the preparation of HAp coatings on various substrates with thickness values ranging from 24 to 53 µm. These coatings exhibited bioactive behavior in simulated body fluid.

Influence of Calcination Temperature on the Physicochemical Properties of Synthesized Hydroxyapatite from Cow Bone Waste

The chemical similarity found in hydroxyapatite (HA) with natural bone makes it a popular choice for bone replacement. Therefore, in recent years, there has been an increasing tendency towards manufacturing HA from biological sources or waste, such as animal bone waste. Using naturally derived HA can benefit the economy, the environment, and human health. Therefore, this paper reports on the extraction of HA from cow bone waste using a simple and cost-effective technique. The bone powder was calcined in a furnace at temperatures ranging from 700°C to 1000°C for two hours. Then, the synthesized HA was characterized using a Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction (XRD). FESEM images revealed that HA particles with non-uniform spherical morphology were produced where the size increases with the calcination temperature. This finding is consistent with the average value of particle diameter measured at a temperature of 1000°C (0.783±0.268 µm) which is much greater than at a temperature of 700°C (0.272±0.128 µm). EDX analysis revealed that the Ca/P ratio value obtained in this study indicates non-stoichiometric HA production. XRD analysis shows that only the HA phase is present and there is no secondary phase generated from the calcination process. Meanwhile, FTIR analysis can detect the main group elements of the HA which were OH- and PO43-. The findings obtained in this study prove the effectiveness of this method in producing highly crystalline HA powder from cow bone waste using the thermal treatment method.

The Role of Fabricated Coral Shell Powder in the Healing of Mandibular Bone Gap in Dogs

Background: The reconstruction of mandibular bone defects poses a real challenge and difficulty for surgeons; biomaterial bone substitutes are the most used material for reconstructing mandibular bone defects. Objectives: This study explored the role of fabricated hydroxyapatite (HAp) powder from the coral shell in healing critical size mandible gaps in dogs. Methods: HAp was prepared using the hydrothermal method from coral shells. Characterization of the fabricated coral shell was done by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDX). The designed research was performed on 18 dogs of both sexes (mean weight: 20±0.5 kg, mean age: 2±0.6 years). The samples were divided into two equal groups. Animals underwent experimental defects at the ventral surface of the lower mandible about 14.5 mm. Results: The results of XRD represented high crystallinity, the EDX results indicated the surface morphology of distributed particles of calcium, phosphorous, carbon, and oxygen, respectively, and the FESEM results suggested that the surface morphology of HAp appears as a spherical particle that regularly distributed within the sample. In the HAp group, at 30 days, the FESEM images show that the defective gap completely closed, and the center of the defect was filled with a thick layer of osteoid matrix. Radiographically, the HAp group at 30 days post-surgery indicated a well-defined circular radiolucent bone gap at the caudal portion of the mandible, with a partially sclerosed margin. Macroscopically, at 30 days, the gap appears very small and is invaded by new bone formation. Conclusion: In conclusion, recycling HAp from coral shells has practical value in the reconstitution of the mandibular gap, and the radiological and critical properties of prepared HAp emphasize this outcome.

Parameters Tailoring on the Deposition of Hydroxyapatite by Pulsed Electrical Discharge.

The creation of strong adhesive layers of hydroxyapatite-based bioceramics (with or without bioinert metals, such as Ta, Ag, and Ti) on biocompatible metallic supports enhances the local biofunctionalization of surfaces. The processing of electroconductive materials using electrical impulse discharges is versatile, enabling precise coating of selected areas with perfectly adherent layers of varying thicknesses. This study aims to quantify the effects of varying the electrical power from the source generating the impulse discharge and the specific processing time per unit area of the cathode (made of titanium alloy) on the relative mass increase of the cathode. The anode comprised a mixture of hydroxyapatite powder and a self-polymerizing electroconductive acrylic resin in a tantalum sheath. The effects of the parameter adjustments on single-layer deposition adherence were quantified using a central composite design to build a second-order orthogonal model. The most significant difference in relative mass was observed with a low-power source (5 W) ensuring the electrical discharge impulse, combined with the longest specified surface treatment time (17.5 s/cm2 on a 4 cm2 surface) for a single layer presenting the largest mass increase of 0.153% of the original mass. This study aimed to enhance the performance of medical implants by optimizing surface biofunctionalization through robust hydroxyapatite-based bioceramic adhesive layers on metallic supports, determining the optimal electrical power and processing time for cathode mass increase during deposition processes, and analyzing parameter adjustments using second-order statistical orthogonal central composite programming, with a focus on single-layer deposition to identify significant differences in relative mass under specific conditions.

Calcium-based triphasic powder synthesis for strengthening 3D printed bone scaffolds

This study aims to improve the mechanical properties of biocompatible ceramic materials, which are known for their superior potential to integrate with bone compared to metallic implants. However, achieving sufficient mechanical strength, particularly for weight-bearing areas, poses a challenge. Hydroxyapatite (HA) powder is synthesized, taking into consideration the mechanical mixing and aging effects to achieve the desired composition and properties. The synthesized HA powder undergoes calcination under various atmospheres to assess its impact on the crystal structure. The study also explores the coating of HA particles with silicon dioxide (SiO2) using tetraethyl orthosilicate (TEOS) to enhance surface modification and wettability. This process results in a triphasic powder consisting of HA, tricalcium phosphate (TCP), and calcium phosphate silicate (CPS). The morphology of the powder is analyzed using techniques such as energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Moreover, a refined sintering procedure is developed to minimize cracking volume, leading to a significant 117 % increase in compressive strength compared to commercial materials. Finally, the powder is optimized for 3D printing by adding water, simplifying its use in biomedical applications.

Phase Transformation and Mechanical Optimization of Eggshell-Derived Hydroxyapatite across a Wide Sintering Temperature Range.

Calcium phosphate, particularly hydroxyapatite (HA), bears a close resemblance to human bones, rendering it a prevalent material in biomedical applications. This study focuses on the successful preparation of HA using a precipitation method with eggshell as a raw material. Subsequently, the HA powder was press-formed and sintered at various temperatures to investigate the impact of sintering temperature on the mechanical properties, including hardness, compressive strength, and fracture toughness, of the sintered HA samples (E-HA). Statistical analyses, including one-way ANOVA and Tukey's post-hoc test, were conducted to determine significant differences in these properties at different sintering temperatures. Experimental findings revealed that as the sintering temperature increased, HA partially transformed into β-TCP between 800 and 1300 °C, with α-TCP observed at 1400 °C. The elimination of pores led to an increase in relative density, with a maximum relative density of 94.5% achieved at 1200 and 1300 °C. E-HA sintered at 1200 °C exhibited the highest hardness (5.08 GPa), compressive strength (255.79 MPa), and fracture toughness (1.21 MPa·m0.5). However, at 1400 °C, a slight decrease in apparent density (2.90 g/cm3) was noted due to the presence of α-TCP, along with significant grain growth. This study's objective is clearly aligned with the study design, incorporating detailed statistical analyses to validate the findings. Furthermore, bacterial culture experiments were conducted using sintered E-HA, Chem-HA (HA synthesized from reagent-grade calcium carbonate), and Comm-HA (commercial HA). Streptococcus mutans was cultured on the surfaces of sintered E-HA, Chem-HA, and Comm-HA samples for 20 h. After culturing, the OD values for all samples were below 0.2, indicating significant antibacterial efficacy. The comparable OD values and bacterial counts (p > 0.05) suggest that the source of HA does not impact its antibacterial properties. This underscores the potential of eggshell-derived HA as an effective material for biomedical applications.

Meso-Macroporous Hydroxyapatite Powders Synthesized in Polyvinyl Alcohol or Polyvinylpyrrolidone Media.

Mesoporous hydroxyapatite (HA) is widely used in various applications, such as the biomedical field, as a catalytic, as a sensor, and many others. The aim of this work was to obtain HA powders by means of chemical precipitation in a medium containing a polymer-polyvinyl alcohol or polyvinylpyrrolidone (PVP)-with concentrations ranging from 0 to 10%. The HA powders were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, atomic emission spectroscopy with inductively coupled plasma, electron paramagnetic resonance, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The specific surface area (SSA), pore volume, and pore size distributions were determined by low-temperature nitrogen adsorption measurements, and the zeta potential was established. The formation of macropores in powder agglomerates was determined using SEM and TEM. The synthesis in 10% PVP increased the SSA from 101.3 to 158.0 m2/g, while the ripening for 7 days led to an increase from 112.3 to 195.8 m2/g, with the total pore volume rising from 0.37 to 0.71 cm3/g. These materials could be classified as meso-macroporous HA. Such materials can serve as the basis for various applications requiring improved textural properties and may lay the foundation for the creation of bulk 3D materials using a technique that allows for the preservation of their unique pore structure.

Controlled release in sodium alendronate/halloysite/hydroxyapatite/gelatin nanocomposite scaffolds: A new insight into bone tissue engineering

The use of smart scaffolds with drug release capabilities is now widely recognized as a key approach in designing hard tissue substitutes. In this study, alendronate sodium (AL) was bound to halloysite nanotube (HNT) sheets through ionic and π-π interactions. Hydroxyapatite (HA) powder was synthesized using the co-precipitation method, and the drug/carrier complex was subsequently incorporated into a hydroxyapatite/gelatin (GEL) matrix. Composite scaffolds of GEL/HA/HNT/AL were then created using a freeze-drying technique. Different concentrations of HNT (0.5 %, 1 %, and 2 %) were tested to determine the optimal formulation. The scaffolds were subjected to extensive physical, chemical, and mechanical evaluations using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), compressive stress tests, and measurements of density and porosity. The release profile of alendronate sodium, scaffold swelling behavior in water, bioactivity, and in vitro performance were thoroughly assessed. Cell viability was tested using the MTT assay, while alkaline phosphatase (ALP) activity and cell adhesion studies were performed to evaluate osteogenic potential. The results revealed that the GEL/HA/1 % HNT/AL nanocomposite scaffold exhibited excellent properties, including efficient drug release, optimal swelling rates, and enhanced bioactivity. The MTT assay confirmed high cell viability, and both ALP activity and cell adhesion studies indicated strong potential for bone cell differentiation and repair. Thus, the GEL/HA/1 % HNT/AL nanocomposite scaffold is a highly promising platform for bone tissue engineering.

Structural, mechanical and in vitro studies on pulsed laser deposition of hydroxyapatite on additive manufactured polyamide substrate

Additive manufacturing (AM) is an emerging field that merges engineering and life sciences to produce components that can effectively act as a replacement in the human body. This AM encompasses biofabrication using cells, biological or biomaterials as building blocks to fabricate biological and bio-application oriented substance, device and therapeutic products through a broad range of engineering and biological processes. Furthermore, bioactive coating on BAM surface facilitates biological fixation between the prosthesis and the hard tissue which increases the long term stability and integrity of the implant. In this paper, hydroxyapatite (HA) powder was coated over AM polyamide substrate using pulsed laser deposition. Coating morphology was characterised using scanning electron microscope (SEM) analysis and observed that the coating was dominated by the presence of particle droplet with different sizes. Compounds like tricalcium phosphate and a few amorphous calcium phosphates were found along with HA which was confirmed by X-ray diffraction (XRD) analysis. Fourier transform infrared spectroscopy (FTIR) techniques shows the presence of phosphate and carbonate groups in the HA structure. Nano-indentation and pull-out test reveals that the layer was strong enough and withstands higher load before it peels off. In vitro analysis was evaluated with human osteosarcoma MG-63 cells with respect to the cell viability and results shows that the good viability was observed on coated surface due to combinational effect of Ca2+ and PO4 3− ions. The multitude of characterisation conducted on the coating has established that coating polyamide with HA results in a positive combination for an implant.

Surface characteristics and machining rate of SS 316L coating developed using hydroxyapatite-mixed EDM process

Hydroxyapatite (HA) or bioceramic-based coatings on stainless steel (SS) 316L significantly enhance the biofunctionality of the base material's surface. However, HA's low thermal conductivity and brittleness limit its effectiveness as a coating material. This study investigates HA coating on SS 316L using electric discharge machining (EDM) with varying discharge energies and powder concentrations. Surface morphology, elemental composition, and phase analysis of untreated and coated samples were characterised using field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The results demonstrate that the HA-assisted EDM process creates a coating comprising biocompatible oxides, phosphates, carbides, and intermetallic compounds. The coating exhibits a thin resolidified layer of 10.74 μm, characterised by redeposited spherical debris, shallow cavities, and a surface texture of 2.688 μm. The layer's hydrophilic nature is confirmed by a minimum contact angle of 47.68°. Taguchi analysis indicates that the machining rate is optimised at an HA powder concentration of 16 g/l, with peak current and HA powder concentration being the most influential parameters affecting resolidified layer thickness, surface texture, and wetting angle. The research intends to motivate SS 316L medical device manufacturers to implement the HA-assisted EDM process for bioimplant's dual machining and coating.

Are we approaching the development of a novel calcium phosphate-based bioceramic dental material?

ObjectivesDevelop a sustainable bovine hydroxyapatite dental ceramic with the addition of titanium dioxide (TiO2) nanoparticles (5 % and 8 % by weight), analyzing the outcome of this addition to the microstructure, as well as its mechanical and chemical properties, in order to evaluate whether they satisfy the International Organization for Standardization (ISO) 6872:2015 for dental ceramics or not. MethodsDisks were obtained through uniaxial followed by isostatic pressing from bovine hydroxyapatite powder and TiO2 nanoparticles and sintered at 1300ºC for 2 h. Three experimental groups were developed (HA, HA+5 %TiO2 and HA+8 %TiO2) and subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), indentation fracture (IF), biaxial flexural strength (BFS) and chemical solubility test. ResultsXRD revealed, for HA group, the appearance of a peak corresponding to b-tricalcium phosphate (ß-TCP). For HA+ 5 %TiO2 and HA+ 8 %TiO2, the entire composition was converted into ß-TCP and calcium titanate (CaTiO3). The SEM images showed a dense ceramic matrix and a uniform distribution of another phase in groups with TiO2 nanoparticles. HA+ 5 %TiO2 (1.40 ± 0.18 MPa.m1/2) and HA+ 8 %TiO2 (1.32 ± 0.18 MPa.m1/2) showed significantly higher fracture toughness values than HA (0.67 ± 0.09 MPa.m1/2). HA showed significantly higher characteristic stress (295.8 MPa) in comparison to groups with 5 % (235.1 MPa) and 8 % (214.4 MPa) TiO2 nanoparticles. Differences were not observed between the Weibull modulus values. The solubility results indicated that all experimental ceramics were above the 2000 ug/cm2 limit set by the ISO 6872:2015. SignificanceThis study proposed the development and characterization of a new ceramic for dental prosthesis made from HA extracted from bovine bones, with the intention of reusing these solids waste and transforming them into a sustainable and low-cost material. Although the experimental calcium phosphate ceramic with additions of 5 % and 8 % of TiO2 achieved desirable mechanical properties, the chemical solubility values were very high.

Preparation and Characterization of Hydroxyapatite Based Composite Material via Cold Sintering Process

This study focuses on the synthesis of hydroxyapatite (HA) from bovine bones through calcination and subsequent combination with Polyvinyl Alcohol (PVA) using the Cold Sintering Process (CSP). The CSP, operating at lower temperatures than conventional methods, aims to preserve the bioactivity and biocompatibility of HA, crucial for biomedical applications. The research investigates the influence of HA composition, sintering temperature, and PVA content on the porosity and compressive strength of the HA-PVA composite. The Hydroxyapatite powder, obtained from calcinated bovine bones, exhibits irregular shapes and sizes with a maximum grain size of 10µm, confirmed by SEM analysis. XRD analysis validates the successful production of Hydroxyapatite, showcasing characteristic peaks. The HA/PVA composite's XRD pattern indicates the dominance of HA, with PVA present as well. The study produces 27 specimens through the CSP, varying HA composition and sintering temperature. Porosity increases with higher HA content and sintering temperature, attributed to the role of PVA in binding HA particles. Compressive strength rises with increased HA content, emphasizing HA's role in enhancing mechanical strength. The presence of porosity is mitigated by a strong bond between HA and PVA, contributing to structural integrity. This research provides insights into tailoring HA-PVA materials for biomedical applications, considering controlled porosity and mechanical strength. The CSP, with its unique advantages, emerges as a promising method for developing customized materials to meet diverse biomedical needs.

Effect of Acetylsalicylic Acid on Biological Properties of Novel Cement Based on Calcium Phosphate Doped with Ions of Strontium, Copper, and Zinc.

This study aimed to compare the biological properties of newly synthesized cements based on calcium phosphate with a commercially used cement, mineral trioxide aggregate (MTA). Strontium (Sr)-, Copper (Cu)-, and Zinc (Zn)-doped hydroxyapatite (miHAp) powder was obtained through hydrothermal synthesis and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry (EDX). Calcium phosphate cement (CPC) was produced by mixing miHAp powder with a 20 wt.% citric acid solution, followed by the assessment of its compressive strength, setting time, and in vitro bioactivity. Acetylsalicylic acid (ASA) was added to the CPC, resulting in CPCA. Biological tests were conducted on CPC, CPCA, and MTA. The biocompatibility of the cement extracts was evaluated in vitro using human dental pulp stem cells (hDPSCs) and in vivo using a zebrafish model. Antibiofilm and antimicrobial effect (quantified by CFUs/mL) were assessed against Streptococcus mutans and Lactobacillus rhamnosus. None of the tested materials showed toxicity, while CPCA even increased hDPSCs proliferation. CPCA showed a better safety profile than MTA and CPC, and no toxic or immunomodulatory effects on the zebrafish model. CPCA exhibited similar antibiofilm effects against S. mutans and L. rhamnosus to MTA.

Polymer-Based Hydroxyapatite-Silver Composite Resin with Enhanced Antibacterial Activity for Dental Applications.

The primary objective of this investigation was to synthesize a resin incorporating nanoparticles of hydroxyapatite and silver (HA-NpsAg) to enhance biocompatibility and antimicrobial efficacy, thereby facilitating potential implementation within the dental industry. These enhancements aim to ensure reliable, durable, functional, and aesthetically pleasing restorations while concurrently reducing susceptibility to bacterial colonization within the oral cavity. Hydroxyapatite powders were prepared using the sol-gel method and doped with silver nanoparticles obtained by chemical reduction. The crystalline amorphous calcium phosphate powder had a particle size of 279 nm, and the silver nanoparticles had an average diameter of 26.5 nm. Resin spheres containing HA-NpsAg (RHN) were then synthesized at two concentrations (0.5% and 1%) by dissolving the initial monomer mixture in tetrahydrofuran. Subsequent antimicrobial evaluations were conducted via agar diffusion and turbidimetry, employing three strains of Gram-negative bacteria (E. coli, K. oxytoca, and P. aeruginosa) and three strains of Gram-positive bacteria (S. mutans, S. aureus, and B. subtilis). The findings revealed that P. aeruginosa exhibited maximum susceptibility to RHN powder at a concentration of 0.5%, while RHN powder at 1% concentration demonstrated maximal inhibition against S. aureus and S. mutans. Overall, our study highlights the successful synthesis of a dental resin with hydroxyapatite and silver nanoparticles, exhibiting bactericidal properties at low silver concentrations. These findings hold promise for enhancing dental materials with improved antimicrobial efficacy and clinical performance.

Ordering of oxygen vacancies in hydroxyapatite under electron irradiation

Understanding the mechanisms of radiation induced defect generation is essential for assessment of materials to be used in nuclear environments. In the current work, we investigate the effect of 10 MeV electron irradiation on the generation and possible ordering of defects/oxygen vacancies in hydroxyapatite (HAP) powders. Comprehensive analyses of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Electron Paramagnetic Resonance (EPR) and Raman spectra establish that (a) HAP has a high level of structural stability even after exposure to electron irradiation; (b) irradiation leads to the generation of surface defects/oxygen vacancy predominantly in the PO43− polyanion site, particularly in part of asymmetric bonding within the P–O bonds and (c) there is noticeable evidence for an ordered arrangement of oxygen vacancies within the HAP irradiated at 1 MGy dose. These radiation-induced defects, such as oxygen vacancies, can migrate within the HAP lattice, leading to formation of defect/oxygen vacancies clusters which ultimately results in the ordering tendency of oxygen vacancies within the lattice. The observed ordering, as evidenced by the photoluminescence intensities, aligns with the sequence HAP-1MGy > HAP-20MGy > HAP, providing further support for the presence of ordered oxygen vacancies.

Sorption of three PAHs profile groups using eco-friendly and inexpensive hydroxyapatite extracted from camel bone

Hydroxyapatite (HAp) was used in the sorption study for three different polycyclic aromatic hydrocarbons (PAHs) ring structures (Naphthalene (NAP), Anthracene (ANT), and Chrysene). HAp powders were produced from Camelus bone as an eco-friendly and inexpensive source. Three distinct surface areas (66.56, 94.88, and 94.35 m2/g) at three different temperatures (500, 650, and 900 °C), were applied to prepare the HAp500, HAp650, and HAp900 samples after passing CO2 at 700 °C. It was obvious that the surface area of HAp was greatest at 650 °C as compared to 500 °C with a very small variation in uptake between HAP650 and HAP900. Furthermore, for ANT, HAp900 provides the best uptake. In addition, HAp650 is the best since calcining at 650 °C is less expensive than calcining at 900 °C. The effect of shaking time on the sorption of NAP, ANT, and CHR dissolved in n-hexane was carried out using HAp650. The impacts of sorbent amount, concentration, and temperature were studied. The study indicated that the uptake was 66.89, 69.49, and 19.67 mg/g after 120 min of equilibration. It was observed that the uptake of NAP, ANT, and CHR increased as the temperature increased up to 35 °C. A slight increase was obtained from 35–55 °C, indicating that the adsorption occurring on the HAp650 surface is endothermic. The positive values of Δ H demonstrated the endothermic nature of the adsorption process. Furthermore, the positive entropy of adsorption represents the adsorbent material’s affinity for NAP, ANT, and CHR. In addition, several isotherm models were used to deduce an adsorption mechanism. The adsorption system’s R2 values were 0.9615 for NAP, 0.8666 for ANT, and 1.00 for CHR. These values agree well with the Langmuir isotherm.

Fabrication of 3D printed hydroxyapatite/polymeric bone scaffold

ABSTRACT Reconstruction in cases of osteoporosis or accidents often requires the use of synthetic bones or scaffolds, with hydroxyapatite standing out as a preferred material due to its biocompatibility. This study focuses on the production and characterization of hydroxyapatite-coated 3D-printed bone scaffolds. The 3D-printed structures were fabricated by blending hydroxyapatite powder, synthesized through the solution combustion technique, with a liquid photopolymer, followed by exposure to UV irradiation. The resulting hydroxyapatite/photopolymer scaffolds were characterized by a uniform distribution of fine hydroxyapatite powder on the surface. Subsequently, these scaffolds underwent coating with a hydroxyapatite slurry, experimenting with various coating and sintering conditions. Despite the decomposition of the photopolymer during the sintering process, the coated scaffold displayed an increased thickness of the infill line within the pattern, resulting in reduced void size and enhanced compressive strength. Weibull analysis of the compressive strength indicated a high likelihood of survival at 4 MPa, falling within the acceptable range for cancellous bone strength. This comprehensive study showcased the potential of hydroxyapatite-coated 3D-printed bone scaffolds with a favorable microstructure and mechanical strength, making them promising for applications in bone reconstruction.

Effects of sintering temperature on the physical, structural, mechanical and antimicrobial properties of extracted hydroxyapatite ceramics from Anabas testudineus bone and head scull for biomedical applications

In this experimental investigation, Hydroxyapatite (HAp) is extracted from bone and head scull of Anabas testudineus by thermal calcination at 800 °C for 5 h under ambient air conditions. Ceramic samples were prepared through compaction and followed by sintering at 1200 °C, 1250 °C, and 1300 °C temperatures for 2 h from the calcined HAp powder. Both the calcined powder and sintered ceramic samples were characterized using X-ray Diffraction (XRD), Energy dispersive X-ray spectroscopy (EDS) and Scanning Electron Microscopy (SEM) to explore the potentiality of the extracted ceramics for biomedical applications. Moreover, the elemental composition, phase structure, compressive strength, Vicker hardness, and antimicrobial characteristics of the ceramic samples have been investigated. The XRD analysis confirmed the presence of hydroxyapatite in both the calcined powder and ceramic samples. Various types of trace elements were observed in HAp ceramics including a noteworthy 1.57 atomic percent of magnesium (Mg). Additionally, the XRD spectrum indicated the existence of the β-tricalcium phosphate (TCP) phase. Upon sintering at a temperature of 1250 °C, the ceramic sample underwent a phase shift to α-TCP. Our results show that the phase transition has a significant effect on the crystallinity of HAp. The ceramics sample sintered at 1300 °C exhibited the highest compressive strength and Vicker Hardness due to its high relative density, well-packed grains, and larger particle size. The sintered sample did not exhibit notable zone of inhibition against Escherichia coli and Staphylococcus aureus bacteria.