Pure HA Research Articles

Development of calcium phosphate cement composed of silica-modified hydroxyapatite, cerium oxide, and silica as an osteoporotic bone filler

Calcium phosphate cement (CPC), composed of silica-modified hydroxyapatite (HA-SiO2), cerium oxide (CeO2), and silica (SiO2), was developed as an osteoporosis bone filler. The effect of CeO2 and SiO2 content on the CPC's properties, such as crystal parameters, surface properties, antibacterial activity, and toxicity properties, were studied. HA-SiO2 was prepared using the sol-gel method, while CeO2 was prepared using the precipitation method. HA in HA-SiO2 has crystal properties similar to pure HA. Synthesized CeO2 contains Ce3+ and Ce4+ ions with Ce3+/Ce4+ = 0.34. Computational calculation predicted that the CeO2 (111) surface and glycine molecule interaction was categorized as chemisorption. Moreover, CeO2 has antibacterial activity toward Escherichia coli and Staphylococcus aureus. Combining HA-SiO2 and CeO2 did not change the adsorption-desorption isotherm curve type, but slightly decreased the surface area, total pore volume, and average pore. Increasing the percentage of CeO2 and adding 10 % SiO2 (w/w) affected the particle's size and CeO2 distribution. However, CPC lost antibacterial activity toward Staphylococcus aureus but adding 10 % SiO2 (w/w) increases the bacterial activity toward Escherichia coli close to that of pure CeO2. The MTT assay using pre-osteoblast MC3T3E1 cells showed that the CPC has IC50 = 4227 μg/ml or is nontoxic.

Bovine-originated xenografts versus synthetic bone grafting materials in lateral maxillary sinus floor augmentation: A systematic review and meta-analysis.

This study aimed to systematically compare the patients undergoing lateral MSFA therapies utilizing bovine-originated xenografts versus varied synthetic bone grafting materials. Pubmed, Scopus, Embase, and Cochrane Library were searched up to April 2023, compensated by a manual search in selected journals. Studies reporting histological outcomes (residual bone graft, newly formed bone, non-mineralized tissue) and clinical outcomes (implant survival, ISQ value) were included. Several analyses were performed, including meta-analysis, sensitivity study, and Egger's regression tests. Sixteen clinical/randomized control trials were included in this systematic review, among which 12 were enrolled in a meta-analysis. The percentage of newly formed bone within the grafted sinuses by hybrid HA/TCP was significantly higher than those by xenografts (WMD 2.85, 95%CI [0.72; 4.99]), but those grafted by pure HA (WMD -1.72, 95%CI [-3.15; -0.29]) or TCP (WMD -7.10, 95%CI [-13.02; -1.17]) were significantly lower than xenograft counterparts. The residual bone graft and non-mineralized tissue yielded by synthetic HA, TCP, and HA/TCP showed no significant differences with the xenograft group. The chemistry of grafted bone substitutes in lateral MSFA influenced the quantity of newly formed bone. Those grafted with hybrid HA/TCP yielded the highest amount of new bone compared to bovine-originated HA. However, this influence was not significant on residual bone graft and non-mineralizedtissue.

Highly precisive arrangement of continuous carbon fiber and its reinforcing effect on hydroxyapatite

In order to efficiently prepare continuous fiber reinforced composites with high mechanical property, a macro-micro operation device was developed to arrange fiber with high precision. Continuous carbon fiber reinforced hydroxyapatite (CF/HA) composites with highly precisive fiber arrangement was subsequently prepared according to a demanded performance. The arranged fiber spacing and fiber angle of the CF preforms by this device was 101.15 ± 11.72 μm and 0.14 ± 0.38°, respectively. Compared to the traditional arrangement with the arranged fiber spacing of about 300–500 μm, the arrangement accuracy by this device enhanced about 66 %–80 %. The continuous CF/HA composites with designed fiber spacing prepared by this device possessed synchronously enhanced toughness and strength. Compressive strength of the CF/HA composites with designed fiber spacing of 300 μm (CF03p/HA) increased by 311.54 % compared with pure HA. Fracture toughness of the CF03p/HA composites was 1.68 MPa m1/2. Even though the fiber content in CF03p/HA composites was only one-sixth to one-tenth of that in the composites prepared by the traditional method, the compressive strength was 4.12 times that of pure HA. The study provides an effective method for preparing micro fiber reinforced composites featuring excellent mechanical performance even by adding low fiber content.

Incorporation of hydroxyapatite and cerium oxide nanoparticle scaffold as an antibacterial filler matrix for biomedical applications.

Managing bone healing is essential for preventing problems such as non-union, bacterial infection, structural instability, psychological, and physical damage in patients. The need to use antibiotics less often has prompted researchers to look at possible substitutes, such as nanoparticles. In this investigation, we choose to employ cerium oxide nanoparticles due to their unique antibacterial properties based on redox reactions. The cerium oxide-hydroxyapatite composite was synthesized, calcined, and ball-milled to create a fine CeO2-HA powder. Luffa cylindrica sponge was used to prepare the scaffold, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structural and morphological features. Rapid upregulation of osteogenesis marker genes confirmed that CeO2-HA nanoparticles in the scaffolds promoted osteoblast cell proliferation and osteogenic differentiation. The cell viability test was conducted by MTT assay. When the CeO2-HA composite was cultured with S. aureus, it showed signs of having more antibacterial efficacy than pure HA.

Preparation of Ordered‐Porous Hydroxyapatite/ β‐Tricalcium Phosphate Composites and Assessment of Sustained Drug‐Release Performance

AbstractHydroxyapatite(HA) has received more and more attention as a drug carrier due to its excellent biocompatibility and bioactivity. However, the poor biodegradability of HA, low drug loading and uncontrollable release rate limits its application. In this paper, in order to study the effect of different HA and tricalcium phosphate (β‐TCP) phase contents on the drug release performance of the composite, co precipitation template method was used to prepare the composite with different Ca/P ratios (1.5~1.63) using polystyrene colloids as templates, and the Ca/P ratio which had the greatest effect on its morphology was selected. With the ibuprofen (IBU) as the drug model, the results showed that the IBU‐loading performance of the composite was significantly better than that of the ordered‐porous pure phase HA. When the Ca/P ratio was 1.5, the composite had the highest adsorption capacity for IBU, reaching 94.5 mg/g. In vitro release tests revealed that IBU release rates from composites with different Ca/P ratios were slower than those from pure‐phase HA in the initial 10 h, and reached the release equilibrium after the subsequent 30 h. Then, when the Ca/P ratio was 1.5, the composite had a cumulative release rate of 86.35 % for IBU. The loading and slow release properties of this ordered porous HA/β‐TCP composite for IBU make it a potential candidate for controlled release of IBU in the future.”

Microstructural, mechanical and corrosion characterization of (C-HA)SiCnws coating on AZ31 magnesium alloy surface

A composite coating was developed to address the issues of low binding force and poor wear resistance of the hydroxyapatite coating on the surface of magnesium alloy. The composite coating, known as (C-HA)SiCnws coating, was prepared on the surface of AZ31 magnesium alloy using the carbonation-oxidation method of phenolic resin and electrophoretic deposition. The (C-HA)SiCnws coating is composed of a carbon coating as the middle layer, a hydroxyapatite coating as the surface layer, and SiC nanowires that connect the carbon layer and the HA coating. The morphology and infrared spectrum of the coating were characterized, and tests were conducted to evaluate the adhesion, wear performance, electrochemical properties, and corrosion resistance of the coating. The results demonstrate that the (C-HA)SiCnws coating is uniform and flat. The adhesion of the coating, as determined by tensile, is 3.51 ± 0.54 MPa, which is 88 % higher than that of the pure HA coating. Furthermore, the wear performance of the (C-HA)SiCnws coating is excellent, with a wear rate of only 0.96 × 10−3 mm3/(N·m), representing a reduction of 68.2 %. Additionally, the (C-HA)SiCnws coating demonstrates a favorable corrosion protection effect in both electrochemical polarization and corrosion tests. Overall, the prepared (C-HA)SiCnws coating exhibits significant enhancements in terms of adhesion, wear resistance, and corrosion resistance.

Hydroxyapatite–Clay Composite for Bone Tissue Engineering: Effective Utilization of Prawn Exoskeleton Biowaste

Hydroxyapatite (HA, Ca10(PO4)6(OH)2)-based porous scaffolds have been widely investigated in the last three decades. HA, with excellent biocompatibility and osteoconductivity, has made this material widely used in bone tissue engineering. To improve the mechano-biological properties of HA, the addition of clay to develop HA-based composite scaffolds has gained considerable interest from researchers. In this study, a cost-effective method to prepare a HA–clay composite was demonstrated via the mechanical mixing method, wherein kaolin was used because of its biocompatibility. Prawn (Fenneropenaeus indicus) exoskeleton biowaste was utilized as a raw source to synthesize pure HA using wet chemical synthesis. HA–clay composites were prepared by reinforcing HA with 10, 20, and 30 wt.% of kaolin via the mechanical mixing method. A series of characterization tools such as XRD, FTIR, Raman, and FESEM analysis confirmed the phases and characteristic structural and vibrations bonds along with the morphology of sintered bare HA, HA–kaolin clay composite, and kaolin alone, respectively. The HA–clay composite pellets, uniaxially pressed and sintered at 1100 °C for 2 h, were subjected to a compression test, and an enhancement in mechanical and physical properties, with the highest compressive strength of 35 MPa and a retained open porosity of 33%, was achieved in the HA–kaolin (20 wt.%) clay composite, in comparison with bare HA. The addition of 20% kaolin to HA enhanced its compressive strength by 33.7% and increased its open porosity by 19% when compared with bare HA. The reinforcement of HA with different amounts (10, 20, 30 wt.%) of kaolin could open up a new direction of preparing biocomposite scaffolds with enhanced mechanical properties, improved wear, and better cell proliferation in the field of bone tissue engineering.

FeIII Chelated with Humic Acid with Easy Synthesis Conditions and Good Performance as Anode Materials for Lithium-Ion Batteries.

In this work, we prepared a green, cheap material by chelating humic acid with ferric ions (HA-Fe) and used it as an anode material in LIBs for the first time. From the SEM, TEM, XPS, XRD, and nitrogen adsorption-desorption experimental results, it was found that the ferric ion can chelate with humic acid successfully under mild conditions and can increase the surface area of materials. Taking advantage of the chelation between the ferric ions and HA, the capacity of HA-Fe is 586 mAh·g-1 at 0.1 A·g-1 after 1000 cycles. Moreover, benefitting from the chelation effect, the activation degree of HA-Fe (about 8 times) is seriously improved compared with pure HA material (about 2 times) during the change-discharge process. The capacity retention ratio of HA-Fe is 55.63% when the current density increased from 0.05 A·g-1 to 1 A·g-1, which is higher than that of HA (32.55%) and Fe (24.85%). In the end, the storage mechanism of HA-Fe was investigated with ex-situ XPS measurements, and it was found that the C=O and C=C bonds are the activation sites for storage Li ions but have different redox voltages.

The establishment of PES/AMPS-PAN ultrafiltration membrane with the property of self-repairing both physical and chemical damage

Cleaning, oxidant, photocatalysis and operation process will cause chemical or physical damage to the membrane, resulting in a loss of membrane integrity. Self-repairing membranes will help solve this problem without expensive integrity monitoring and membrane replacement. Therefore, this work first prepared the self-repairing PES/AMPS-PAN ultrafiltration membrane that can self-heal both physical damage and chemical damage. AMPS and AMPS-PAN were employed as self-repairing polymers to construct self-repairing membrane. The SEM images, the recovery rate of pure water flux and HA retention rate proved that the PES/AMPS-PAN membrane could realize physical self-repairing process. The XPS result proved that the CC in AMPS and the PES breaking chain underwent a single electron michael addition reaction when the membrane was chemical damaged, realizing the self-repairing of chemical damage. Furthermore, the hydrophilic group in AMPS or AMPS-PAN endowed the membrane hydrophilicity and improved the anti-fouling performance of the membrane. The prepared membrane also illustrated excellent permeability, just like the pure water flux got to 121 L/m2h, while HA retention rate could also maintained at a high level 99.2%. The membranes with different mass ratio of AMPS-PAN (MPAN1 and MPAN3) displayed a better pure water flux recovery rate 90.2% and 92% after chemical cleaning compared with the membrane with no AMPS-PAN (MAMPS0), respectively. The Rir = 18.5% of MPAN3 indicated that the adsorption of HA was prevented by the addition of AMPS-PAN. In a word, the PES/AMPS-PAN membrane not only could self-heal both physical damage and chemical membrane damage, but also endowed the membrane good pollution resistance and permeability.

Microporous Hydroxyapatite-Based Ceramics Alter the Physiology of Endothelial Cells through Physical and Chemical Cues.

Incorporation of silicate ions in calcium phosphate ceramics (CPC) and modification of their multiscale architecture are two strategies for improving the vascularization of scaffolds for bone regenerative medicine. The response of endothelial cells, actors for vascularization, to the chemical and physical cues of biomaterial surfaces is little documented, although essential. We aimed to characterize in vitro the response of an endothelial cell line, C166, cultivated on the surface CPCs varying either in terms of their chemistry (pure versus silicon-doped HA) or their microstructure (dense versus microporous). Adhesion, metabolic activity, and proliferation were significantly altered on microporous ceramics, but the secretion of the pro-angiogenic VEGF-A increased from 262 to 386 pg/mL on porous compared to dense silicon-doped HA ceramics after 168 h. A tubulogenesis assay was set up directly on the ceramics. Two configurations were designed for discriminating the influence of the chemistry from that of the surface physical properties. The formation of tubule-like structures was qualitatively more frequent on dense ceramics. Microporous ceramics induced calcium depletion in the culture medium (from 2 down to 0.5 mmol/L), which is deleterious for C166. Importantly, this effect might be associated with the in vitro static cell culture. No influence of silicon doping of HA on C166 behavior was detected.

Improving the corrosion resistance and the osteointegration of hydroxyapatite coatings through the incorporation of synthesized mesoporous SiO2/HA particles

In the present article, mesoporous SiO2/hydroxyapatite (HA) composite particles were produced via employing CTAB as a template, and then co-electrodeposited on Nitinol biomedical alloy with HA. Characterization results showed the formation of about 200 nm spheres with numerous plate-like particles and slit-shaped pores. The composite coatings were applied by using different concentrations of particles in the deposition electrolyte (500, 750, 1000, and 1250 mg/L). Morphological observations revealed that with an increase in particle concentration, the film exhibited greater compactness, leading to the formation of particle agglomerates in certain regions. This was further proved by the atomic force microscopy analysis where the porosity of the layers decreased, and the roughness diminished by raising particle concentration. This made composite coatings a little more hydrophobic than pure HA coating. Furthermore, the incorporation of these particles significantly enhanced the corrosion protection of the composite coatings. Specifically, the corrosion current density for the sample coated with a solution containing 1000 mg/L of particles decreased to nearly one-fifth of that observed in the pure HA coating. Last but not least, MG-63 osteoblasts were provided with a convenient environment on composite coatings since they fed on Si nutritious element to reproduce and proliferate more aggressively than on pure HA layer.

Biological Response of Human Gingival Fibroblasts to Zinc-Doped Hydroxyapatite Designed for Dental Applications-An In Vitro Study.

This study aimed to investigate the biological response induced by hydroxyapatite (HAp) and zinc-doped HAp (ZnHAp) in human gingival fibroblasts and to explore their antimicrobial activity. The ZnHAp (with xZn = 0.00 and 0.07) powders, synthesized by the sol-gel method, retained the crystallographic structure of pure HA without any modification. Elemental mapping confirmed the uniform dispersion of zinc ions in the HAp lattice. The size of crystallites was 18.67 ± 2 nm for ZnHAp and 21.54 ± 1 nm for HAp. The average particle size was 19.38 ± 1 nm for ZnHAp and 22.47 ± 1 nm for HAp. Antimicrobial studies indicated an inhibition of bacterial adherence to the inert substrate. In vitro biocompatibility was tested on various doses of HAp and ZnHAp after 24 and 72 h of exposure and revealed that cell viability decreased after 72 h starting with a dose of 31.25 µg/mL. However, cells retained membrane integrity and no inflammatory response was induced. High doses (such as 125 µg/mL) affected cell adhesion and the architecture of F-actin filaments, while in the presence of lower doses (such as 15.625 µg/mL), no modifications were observed. Cell proliferation was inhibited after treatment with HAp and ZnHAp, except the dose of 15.625 µg/mL ZnHAp at 72 h of exposure, when a slight increase was observed, proving an improvement in ZnHAp activity due to Zn doping.

Effect of stearic acid on the mechanical and rheological properties of PLA/HA biocomposites

In this study, biocomposite filaments of polylactic acid (PLA) combined with stearic acid (SA)-coated nano-hydroxyapatite (HA) filler were prepared and characterized. These filaments were then used in material extrusion (MEX) additive manufacturing via fused deposition modeling (FDM) to create scaffolds for bone tissue engineering (BTE). Initially, HA was characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and the Rietveld method. Particle size distribution was examined through dynamic light scattering (DLS), and its specific surface area was determined by the Brunauer-Emmett-Teller (BET) method. Subsequently, the HA nanoparticles were coated with stearic acid (SA) to explore its potential as a surfactant for PLA/HA nanocomposites. For composite fabrication, pure HA and SA-coated HA were mixed with PLA in a torque rheometer to obtain PLA/HA and PLA/HA-SA biocomposites. Their flow behavior was evaluated using a slit die rheometer, demonstrating that the SA coating improved rheological properties. The composites were extruded to produce 1.75 mm diameter filaments, which were analyzed by mechanical tensile testing, showing that the SA coating reduced the fragility of the PLA/HA filaments. The filaments exhibited high repeatability in terms of quality, facilitating scaffold printing. The FDM-manufactured scaffolds were analyzed through compressive testing, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and AlamarBlue Cell Viability Analysis. The results demonstrated that these scaffolds possess the required mechanical, thermal, and cytotoxicity properties for applications in bone tissue engineering.

Synthesis and development of novel spherical mesoporous SiO2/HA particles and incorporating them in electrodeposited hydroxyapatite coatings for biomedical applications

In this work, mesoporous SiO2/HA particles were synthesized and were electrodeposited on NiTi along with hydroxyapatite. Characterization of the mesoporous particles showed spheres with a diameter of around 200 nm, including many plate-like particles which produced slit-shape pores. The composite coatings were formed by using various concentrations of particles inside the electrodeposition bath of HA. The objectives of the added mesoporous particles are to increase the mechanical and biological performances of the coatings. Morphological observations demonstrated that as the amount of particles increased, the number of HA nuclei on layers increased, and coatings became denser, having particle agglomerates in some regions. XRD patterns indicated that the mesoporous particles do not affect the crystalline texture of the HA and just increase the crystallization degree of the coating. The obtained AFM results showed the reverse effect of particles on the coatings roughness. The bonding strength of coatings took great advantage of particles and raised from 16.3 MPa for pure HA coating to 31.93 MPa for the coating formed in the solution containing 1000 mg/L of particles. However, further inclusion of particles was harmful in this case. Apatite formation was greatly improved thanks to mesoporous particles. They provided many active sites for nucleation and crystallization of apatite with smaller and regular sizes. Last but not least, cytotoxicity results obtained by culturing fibroblasts showed that the addition of an optimum number of mesoporous SiO2/HA particles was beneficial. The addition of a proper amount of mesoporous SiO2/HA particles with excellent mechanical and biological properties to the electrodeposited HA coating is a promising approach to improve the final clinical performance of the coatings.

Green synthesis of graphene-hydroxyapatite nanocomposites with improved mechanical properties for bone implant materials

Herein, an in-situ synthesis of reduced graphene oxide-hydroxyapatite (RGO-HA) nanocomposites via a green reduction protocol is presented. 0.5, 1.0, and 1.5 wt% of RGO in HA are obtained by reducing the precursor solution with custard apple leaf extract. The 10x5 mm-sized discs of the RGO-HA nanocomposites are prepared and investigated for their mechanical properties. The presence of graphene in the composites is confirmed by UV–Visible, Raman spectroscopic techniques while XRD spectral analysis confirmed the α-tricalcium phosphate (TCP, JCPDS PDF No 00-009-0432) structure of HA. Nanoindentation and Vicker indentation studies revealed the enhancement in the mechanical properties of RGO-HA nanocomposites: elastic modulus, microhardness, and fracture toughness values are enhanced by 100%, 33.3%, and 64.5 %respectively for 1.5 wt% of graphene in HA matrix. The FE SEM analysis of the indentation cracks revealed that the wrapped and tucked graphene sheets in the HA matrix have hindered the propagation of the crack through pull-out, ridge growth, bridging, and deflection mechanisms. Nano scratch analysis revealed the enhanced surface roughness (120%) and coefficient of friction (102%) for 1.5 wt% composites than pure HA. The same composite showed 100% viability of HEK 293 cells at 12.5 μg/mL concentration and in vitro apatite mineralization when immersed for 7 days under SBF solution.

The effect of ZnO nanoparticles on nanomechanical behavior of Hydroxyapatite electrodeposited on NiTi biomedical alloy

This paper aims at surface characterization, chemical composition, and mechanical properties of Hydroxyapatite/ZnO (HA/ZnO) nanocomposite coatings on NiTi biomedical alloy. Morphological observations by FESEM and AFM techniques showed that ZnO NPs were responsible for a uniform, porous HA matrix. XRD analysis proved the pure HA phase synthesis in the presence of ZnO NPs; without them, there were other secondary CaP phases. XPS chemical state investigations firmly confirmed the presence of ZnO NPs by showing peaks at 531.05 eV (O ─ Zn bond) and 1021.82 eV (Zn ─ O bond). Nano-hardness test highlighted a significant enhancement in hardness of composite coating (0.37 GPa) compared to pure HA coating (0.19 GPa). The notable point was that HA/ZnO nanocomposite exhibited more plasticity than HA simple coating. This is beneficial as it provides a comfortable spot for cellular activities. Last but not least, the nano-scratch analysis revealed a great effect of ZnO inclusion on reducing friction coefficient by around 40%. The critical load was also much higher for HA/ZnO composite coating (91.4 mN) than HA coating (58.5 mN). Owing to higher plasticity and lower friction coefficient, HA/ZnO composite managed to ease the movement of the indenter tip on its surface, thereby suffering less shear stress.

Biological characterization of the zinc-modified hydroxyapatite coated by a pulsed laser deposition method

Pure Hydroxyapatite (Ca10(PO4)6(OH)2) and Zn-HA nanoparticles were successfully deposited on steel substrates, and laser ablation was performed by the pulsed laser deposition (PLD) technique using an Nd: YAG laser (λ = 532 nm, τ = 12 ns). The bioactivity of the thin film was investigated by its immersing in a simulated body fluid solution of pH 7.4 at 37 °C for incubation of 14 days. The growth of the apatite layer after immersion was studied. The analysis showed the formation of needle-like crystals after immersion in solution. Wettability angles decreased for the HA coating after post-deposition compared to pure HA coatings at room temperature and ion substitutions in bioceramics lead to wettability modification. The findings confirm that Zn doping with different concentrations improved antibacterial activity. The results demonstrate that coating the surface with bioactive materials modified with metal ions, yields good biological responses, and varied compositions differentially affect the water contact angles as well as HA layer growth.

Versatile-in-All-Trades: Multifunctional Boron-Doped Calcium-Deficient Hydroxyapatite Directs Immunomodulation and Regeneration.

Osseointegration of implants depends on several intertwined factors: osteogenesis, angiogenesis, and immunomodulation. Lately, novel reinforcements allowing faster bonding with osseous tissue have been explored intensively. In this study, we hypothesized the use of boron as a major multifunctional ion to confer versatility to calcium-deficient hydroxyapatite (cHA) synthesized by a wet precipitation/microwave reflux method. By synthesis of boron-doped calcium-deficient hydroxyapatite (BcHA), we expected to obtain an osteoimmunomodulatory and regenerative nanoreinforcement. BcHA was found to possess a pure HA phase, a greater surface area (66.41 m2/g, p = 0.028), and cumulative concentrations of Ca (207.87 ± 6.90 mg/mL, p < 0.001) and B (112.70 ± 11.79 mg/mL, p < 0.001) released in comparison to cHA. Osteogenic potential of BcHA was analyzed using human fetal osteoblasts. BcHA resulted in a drastic increase in the ALP activity (1.11 ± 0.11 mmol/gDNA·min, p < 0.001), biomineralization rate, and osteogenic gene expressions compared to cHA. BcHA angiogenic potential was investigated using human umbilical cord vein endothelial cells. Significantly, the highest VEGF-A release (1111.14 ± 87.82 in 4 h, p = 0.009) and angiogenic gene expressions were obtained for BcHA-treated samples. These samples were also observed to induce a more prominent and highly branched tube network. Finally, inflammatory and inflammasome responses toward BcHA were elucidated using human monocyte-derived macrophages differentiated from THP-1s. BcHA exhibited lower CAS-1 release (50.18 ± 5.52 μg/gDNA μg/gDNA) and higher IL-10 release (126.97 ± 15.05 μg/gDNA) than cHA. In addition, BcHA treatment led to increased expression of regenerative genes such as VEGF-A, RANKL, and BMP-2. In vitro results demonstrated that BcHA has tremendous osteogenic, angiogenic, and immunomodulatory potential to be employed as a “versatile-in-all-trades” modality in various bone tissue engineering applications.

Novel 8%‐TiO2‐nanoparticle‐reinforced dense polycrystalline bovine hydroxyapatite bioceramic

AbstractThis study aimed to produce and characterize the microstructure and mechanical properties of dense polycrystalline bovine hydroxyapatite (DPBHA) bioceramics with 5% and 8% of TiO2 nanoparticles after final synthetization for future use in dental implants. Structural characterization was obtained from analyzes by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscope, energy dispersive spectroscopy, and relative density and apparent porosity. The mechanical characterization was performed by measuring the fracture toughness after three‐point flexural strength (FS) test. The microstructural characterization results showed no secondary phase formation and nonhomogeneous nanoparticle dispersion in HA matrix. DPBHA/Np8% (2.9 ± 0.09 g/cm3) exhibited significantly greater density than DPBHA (2.7 ± 0.03 g/cm3) (p = 0.011) and DPBHA/Np5% (2.7 ± 0.05 g/cm3) (p = 0.041). DPBHA (0.9%) had the smallest porosity followed by DPBHA/Np8% (3.4%). DPBHA/Np5% (4.5%) exhibited the greatest proportion of pores. Pure HA (51.7 ± 10.3 MPa) and DPBHA/Np8% (47.4 ± 6.4 MPa) had significant greater FS (p &lt; 0.001) than DPBHA/Np5% (28.8 ± 3.1 MPa). DPBHA (0.43 ± 0.01 MPa m1/2) and DPBHA/Np8% (0.40 ± 0.06 MPa m1/2) presented greater KIc than DPBHA/Np5% (0.23 ± 0.02 MPa m1/2) (p &lt; 0.003; p &lt; 0.007). In conclusion, 8% TiO2 nanoparticle addition to this synthesis would be a promising HA blend, as mechanical properties were similar, and the relative density/apparent porosity showed superior results than those of the DPBHA.

Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products

The purpose of this method is to provide an accurate and precise concentration of humic (HA) and/or fulvic acids (FA) in soft coals, humic ores and shales, peats, composts and humic substance-containing commercial products. The method is based on the alkaline extraction of test materials, using 0.1 N NaOH as an extractant, and separation of the alkaline soluble humic substances (HS) from nonsoluble products by centrifugation. The pH of the centrifuged alkaline extract is then adjusted to pH 1 with conc. HCl, which results in precipitation of the HA. The precipitated HA are separated from the fulvic fraction (FF) (the fraction of HS that remains in solution,) by centrifugation. The HA is then oven or freeze dried and the ash content of the dried HA determined. The weight of the pure (i.e., ash-free) HA is then divided by the weight of the sample and the resulting fraction multiplied by 100 to determine the % HA in the sample. To determine the FA content, the FF is loaded onto a hydrophobic DAX-8 resin, which adsorbs the FA fraction also referred to as the hydrophobic fulvic acid (HFA). The remaining non-fulvic acid fraction, also called the hydrophilic fulvic fraction (HyFF) is then removed by washing the resin with deionized H2O until all nonabsorbed material is completely removed. The FA is then desorbed with 0.1 N NaOH. The resulting Na-fulvate is then protonated by passing it over a strong H+-exchange resin. The resulting FA is oven or freeze dried, the ash content determined and the concentration in the sample calculated as described above for HA.