Commercial Hydroxyapatite Research Articles

Influence of manufacturing parameters on bioactive glass 45S5: Structural analysis and applications in bone tissue engineering

Bioactive glass (BG-45S5) production through the melting process is affected by a wide variety of parameters. This study investigated the synthesis of BG-45S5 granules and the process variables to produce a bioactive and osteoinductive BG for bone grafting applications. The melting process was initially analyzed by varying parameters such as crucible type and pouring environment using P2O5 as phosphorus precursor. The obtained products were characterized by crystalline phases, characteristic chemical groups, particle size distribution, and chemical composition. Materials poured into graphite or steel molds resulted in particle sizes more suitable for applications in granular form. Using a platinum crucible yielded a chemical composition closer to the target when compared with another ceramic crucible. Subsequently, the melting process was evaluated to different phosphorus precursor (P2O5 or Na2HPO4) and melting duration (1 or 2 h) in a platinum crucible verifying their effects on the thermal behavior, chemical composition and structure of BG-45S5. Employing Na2HPO4 as a precursor led to higher glass transition and crystallization temperatures as compared to P2O5, enhancing glass homogeneity and structural stability. The product with better characteristics in terms of composition and structure was further characterized for bioactivity and cell culture behavior, showing a greater amount of mineralization nodules when compared to commercial hydroxyapatite. This is particularly due to its behavior as the solubility and interaction in biological environments.

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.

Insect Cell-Based Quadrivalent Seasonal Influenza Virus-like Particles Vaccine Elicits Potent Immune Responses in Mice.

Influenza viruses can cause highly infectious respiratory diseases, posing noteworthy epidemic and pandemic threats. Vaccination is the most cost-effective intervention to prevent influenza and its complications. However, reliance on embryonic chicken eggs for commercial influenza vaccine production presents potential risks, including reductions in efficacy due to HA gene mutations and supply delays due to scalability challenges. Thus, alternative platforms are needed urgently to replace egg-based methods and efficiently meet the increasing demand for vaccines. In this study, we employed a baculovirus expression vector system to engineer HA, NA, and M1 genes from seasonal influenza strains A/H1N1, A/H3N2, B/Yamagata, and B/Victoria, generating virus-like particle (VLP) vaccine antigens, H1N1-VLP, H3N2-VLP, Yamagata-VLP, and Victoria-VLP. We then assessed their functional and antigenic characteristics, including hemagglutination assay, protein composition, morphology, stability, and immunogenicity. We found that recombinant VLPs displayed functional activity, resembling influenza virions in morphology and size while maintaining structural integrity. Comparative immunogenicity assessments in mice showed that our quadrivalent VLPs were consistent in inducing hemagglutination inhibition and neutralizing antibody titers against homologous viruses compared to both commercial recombinant HA and egg-based vaccines (Vaxigrip). The findings highlight insect cell-based VLP vaccines as promising candidates for quadrivalent seasonal influenza vaccines. Further studies are worth conducting.

Manufacturing of 3D-Printed Hybrid Scaffolds with Polyelectrolyte Multilayer Coating in Static and Dynamic Culture Conditions.

Three-dimensional printing (3DP) has emerged as a promising method for creating intricate scaffold designs. This study assessed three 3DP scaffold designs fabricated using biodegradable poly(lactic) acid (PLA) through fused deposition modelling (FDM): mesh, two channels (2C), and four channels (4C). To address the limitations of PLA, such as hydrophobic properties and poor cell attachment, a post-fabrication modification technique employing Polyelectrolyte Multilayers (PEMs) coating was implemented. The scaffolds underwent aminolysis followed by coating with SiCHA nanopowders dispersed in hyaluronic acid and collagen type I, and finally crosslinked the outermost coated layers with EDC/NHS solution to complete the hybrid scaffold production. The study employed rotating wall vessels (RWVs) to investigate how simulating microgravity affects cell proliferation and differentiation. Human mesenchymal stem cells (hMSCs) cultured on these scaffolds using proliferation medium (PM) and osteogenic media (OM), subjected to static (TCP) and dynamic (RWVs) conditions for 21 days, revealed superior performance of 4C hybrid scaffolds, particularly in OM. Compared to commercial hydroxyapatite scaffolds, these hybrid scaffolds demonstrated enhanced cell activity and survival. The pre-vascularisation concept on 4C hybrid scaffolds showed the proliferation of both HUVECs and hMSCs throughout the scaffolds, with a positive expression of osteogenic and angiogenic markers at the early stages.

Deep dewatering of sludge and resource recovery of hydroxyapatite: A recyclable approach via ionic liquid biphasic system and hydrogen bonds reformation

Deep dewatering of Waste Activated Sludge (WAS) through mechanical processes remains inefficient, primarily due to the formation of a stable hydrogen bonding network between the biopolymers and water, which consequently leads to significant water trapped by Extracellular Polymeric Substances (EPS). In this study, a novel and recyclable treatment for WAS based on Ionic Liquids (ILs) was established, named IL-biphasic aqueous system (IL-ABS) treatment. Specifically, the IL-ABS formed in WAS facilitated rapid and efficient in-situ deep dewatering while concurrently recovering hydroxyapatite. The water content decreased from an initial 98.27 % to 65.35 % with IL-ABS, formed by 1-Butyl-3-methylimidazolium bromide (BmimBr) and K3PO4 synthesized from waste H3PO4. Moreover, the recycled BmimBr maintaining the water content of the dewatered sludge consistently between 65.61 % and 67.25 % across five cycles, exhibited remarkable reproducibility. Through three-dimensional excitation-emission matrix, lactate dehydrogenase analyses and confocal laser scanning microscopy, the high concentration of BmimBr in the upper phase effectively disrupted the cells and EPS, which exposed protein and polysaccharide on the EPS surface. Subsequently, the K3PO4 in the lower phase led to an enhanced salting-out effect in WAS. Furthermore, FT-IR analysis revealed that K3PO4 disrupted the original hydrogen bonds between EPS and water. Then, BmimBr formed numerous hydrogen bonds with the sludge flocs, leading to deep dewatering and agglomeration of the sludge flocs during the unique phase separation process of IL-ABS. Notably, sludge-derived hydroxyapatite product exhibited remarkable adsorption capacity for prevalent heavy metal contaminants such as Pb2+, Cd2+ and Cu2+, with efficiencies comparable to those of commercial hydroxyapatite, thereby achieving the resource utilization of waste H3PO4. Moreover, economic calculations demonstrated the suitability of this novel treatment. This innovative treatment exhibits potential for practical applications in the non-mechanical deep dewatering of WAS.

Complete genome sequence of Delftia tsuruhatensis strain HA60 isolated from a commercial hydroxyapatite nano-particle product (nano-hydroxyapatite).

Delftia tsuruhatensis is a Gram-negative rod-shaped aerobic bacterium with environmental remediation functions. D. tsuruhatensis strain HA60 was isolated from a commercial nano-particle product, nano-hydroxyapatite. We report that the genome of D. tsuruhatensis strain HA60 has a circular genome of 6,922,195 base pairs with a G+C content of 66.45%.

Sintered fluorapatite scaffolds as an autograft-like engineered bone graft.

Hydroxyapatite (HA)-based materials are widely used as bone substitutes due to their inherent biocompatibility, osteoconductivity, and bio-absorption properties. However, HA scaffolds lack compressive strength when compared to autograft bone. It has been shown that the fluoridated form of HA, fluorapatite (FA), can be sintered to obtain this desired strength as well as slower degradation properties. Also, FA surfaces have been previously shown to promote stem cell differentiation toward an osteogenic lineage. Thus, it was hypothesized that FA, with and without stromal vascular fraction (SVF), would guide bone healing to an equal or better extent than the clinical gold standard. The regenerative potentials of these scaffolds were tested in 32 Lewis rats in a femoral condylar defect model with untreated (negative), isograft (positive), and commercial HA as controls. Animals were survived for 12 weeks post-implantation. A semi-quantitative micro-CT analysis was developed to quantify the percent new bone formation within the defects. Our model showed significantly higher (p < .05) new bone depositions in all apatite groups compared to the autograft group. Overall, the FA group had the most significant new bone deposition, while the differences between HA, FA, and FA + SVF were insignificant (p > .05). Histological observations supported the micro-CT findings and highlighted the presence of healthy bone tissues without interposing capsules or intense immune responses for FA groups. Most importantly, the regenerating bone tissue within the FA + SVF scaffolds resembled the architecture of the surrounding trabecular bone, showing intertrabecular spaces, while the FA group presented a denser cortical bone-like architecture. Also, a lower density of cells was observed near FA granules compared to HA surfaces, suggesting a reduced immune response. This first in vivo rat study supported the tested hypothesis, illustrating the utility of FA as a bone scaffold material.

Fluoride adsorption on hydroxyapatite: From batch to continuous operation

In the present paper, the removal of fluoride from drinking was investigated via adsorption technique, an important contaminant that could cause serious threat to human health. The challenge of this work is the scale-up from batch to continuous operation, including regeneration of the adsorbent, using a commercial hydroxyapatite, namely Fuorandel®. Adsorption Dynamic Intraparticle Model (ADIM) was used to describe the data collected in batch mode, obtaining important parameters to design a continuous adsorption column, such as: surface diffusivity, DS, and tortuosity, τ. Those parameters were fixed to simulate the experimental data collected in a continuous device obtaining good results. Finally, the sorbent regeneration in a batch system was investigated, optimizing the conditions to enhance Fluorandel® recovery. The present paper shows clearly the potential application of the selected sorbent, giving all the tools needed to scale-up the operation at industrial level.

Synthesis of stabilized zero-valent iron particles and role investigation of humic acid-Fex+ shell in Fenton-like reactions and surface stability control

Herein, a novel humic acid-Fex+ complex-coated ZVI (HA-Fex+@ZVI) was synthesized and used to activate peroxydisulfate (PDS) for phenol degradation. The HA-Fex+ shell selectively reacted with PDS rather than O2, leading to the formation of modified ZVI with excellent surface stability in storage and ultraefficient PDS activation in advanced oxidation processes (AOPs). As a result, the phenol degradation and PDS activation efficiencies of HA-Fex+@ZVI/PDS were ∼14.4 and ∼1.8 times higher than those of ZVI/PDS, respectively. Mechanistic explorations revealed that the replacement of the HA-Fex+ shell relative to the original passivation layer of ZVI greatly changed the SO4•- generation pathway from a heterogeneous process to a homogeneous process, resulting from the slow exposure of Fe0 (generating dissolved Fe2+) and the depolymerized HA (enhancing the Fe3+/Fe2+ cycle). Based on experimental analysis and density functional theory (DFT) calculations, the Fe3+ in HA-Fex+ could be reduced to Fe2+ by PDS, resulting in the disintegration of the HA-Fex+ shell and exposure of Fe0 core active sites. Furthermore, compared to similar catalysts synthesized with commercial HA and traditional chemicals, HA-Fex+@ZVI synthesized with multiple waste biomasses exhibited better performance. This research provides valuable insights for designing ZVI-based catalysts with excellent storage stability and ultraefficient PDS catalytic activity for AOPs.

Preparation of hydroxyapatite (HAP) from waste eggshells for enhancing the granulation and treatment performance of aerobic granular sludge: Enhancement effects and mechanism insights

Hydroxyapatite (HAP), an inorganic mineral that is generated in situ within the core of aerobic granular sludge (AGS), plays a pivotal role in both the granulation process and system stability. Due to the slow precipitation rate of HAP, waste eggshells were utilized as a readily available source for preparing HAP by using the conventional hydrothermal (C-HAP) and microwave hydrothermal (M-HAP) methods. Subsequently, the prepared HAP was employed to promote AGS formation. Results showed that the prepared HAP exhibits superior morphology, crystallinity, functional groups, and specific surface area compared to the commercial grade HAP, whereby M-HAP outperforms C-HAP for functional groups and specific surface area. The addition of 0.5 g/L HAP facilitated the granulation process (within 20 days), leading to the development of structurally compact AGS, which was attributed to the microbial attachment onto HAP particles. Moreover, the presence of HAP greatly improved the nutrient removal efficiency (80.8 % of TN and 82.4 % of PO43−-P), most likely due to the enrichment of denitrifying and phosphorus-accumulating microorganisms (e.g., Candidatus_Competibacter and Flavobacterium). Further analysis revealed that an increase in the relative abundance of denitrification-related genes (e.g., narG and nirK) was responsible for the intrinsic mechanism behind the enhanced nitrogen removal, while phosphorus removal occurred through biomineralization and abiotic precipitation pathways. Overall, the present study highlights the potential of utilizing waste eggshells to enhance AGS systems for wastewater treatment, thus realizing a circular economy approach.

Comparative study of hydroxyapatite synthesized using Schiff base and wet chemical precipitation methods

Hydroxyapatite (HAp) exists as an inorganic and crystalline composition present in bones and dental enamel, and hence can be utilized as a direct element or as part of the composition of biomaterials and implants for dental and orthopaedic applications. Listed below are a few synthesis techniques for HAp that are listed in the literature: solid-state and mechano-chemical methods (dry methods), wet chemical precipitation and sol-gel methods (wet methods), and combustion and pyrolysis methods (high-temperature processes). Nevertheless, there are new and more productive techniques that result in HAp with a regulated morphology, such as the Schiff base method, which, on reaction with calcium and phosphate precursors, forms chelating complexes to produce HAp nuclei. This research paper presents the comparison in characteristics between HAp synthesized using Schiff base (HAp-SB), wet chemical precipitation (HAp-WC) methods, and commercial HAp (HAp-CM) in their powdered and pelleted form. The average size of HAp-WC particles in the spherical form was found to be 603 nm ± 176, HAp-SB were found to have rod-like morphology, which is very similar to human bone-like HAp, with an average length and width of 1522 nm ± 759 and 400 nm ± 112, respectively, and HAp-CM were found to have spherical morphology with dimensions of 52 nm ± 25. Biological studies show that cell viability of HAp-SB pellet (202.01% ± 8.16) seemed to have higher cell proliferation properties than HAp-WC pellet (145.7% ± 5.11) and HAp-CM pellet (71.53% ± 3.61) due to its higher aspect ratio, and hence higher surface area for the cells to adhere. In a detailed study, it is observed that both techniques had their advantages, and there were no significant disadvantages observed.

Biphasic Bioceramic Obtained from Byproducts of Sugar Beet Processing for Use in Bioactive Coatings and Bone Fillings.

This study focuses on developing hydroxyapatite synthesized from a CaCO3-rich byproduct of sugar beet processing called Carbocal® using a hydrothermal reactor. The purpose of this biomaterial is to enhance the osteoinductivity of implantable surfaces and serve as a bone filler, providing a sustainable and economically more affordable alternative. This research involved compositional analysis and micro- and macrostructural physicochemical characterization, complemented with bioactivity and live/dead assays. The biphasic nature of the Carbocal®-derived sample was significant within the context of the bioactivity concept previously proposed in the literature. The bioactivity of the biomaterial was demonstrated through a viability test, where the cell growth was nearly equivalent to that of the positive control. For comparison purposes, the same tests were conducted with two additional samples: hydroxyapatite obtained from CaCO3 and commercial hydroxyapatite. The resulting product of this process is biocompatible and possesses properties similar to natural hydroxyapatite. Consequently, this biomaterial shows potential as a scaffold in tissue engineering and as an adhesive filler to promote bone regeneration within the context of the circular bioeconomy in the geographical area proposed.

Identification of Proteins Adsorbed on Hydroxyapatite Ceramics with a Preferred Orientation to a-Plane

Protein adsorption is essential for determining material biocompatibility and promoting adherent cell growth. In this study, we focused on the a-plane structure of hydroxyapatite (HAp). This a-plane structure closely resembles the crystal plane where apatite is exposed in long bones. We conducted protein adsorption experiments using HAp ceramics with a preferred orientation to a-planes (aHAp), employing bovine serum albumin (BSA), lysozyme, and fetal bovine serum (FBS) as protein models to mimic the in vivo environment. Higher zeta potential and contact angle values were found in aHAp than in HAp ceramics fabricated from commercial HAp powder (iHAp). Bradford-quantified protein adsorption revealed BSA adsorption of 212 ng·mm−2 in aHAp and 28.4 ng mm−2 in iHAp. Furthermore, the Bradford-quantified protein adsorption values for FBS were 2.07 μg mm−2 in aHAp and 1.28 µg mm−2 in iHAp. Two-dimensional electrophoresis (2D-PAGE) showed a higher number of protein-derived major spots in aHAp (37 spots) than in iHAp (12 spots). Mass spectrometry analysis of the resulting 2D-PAGE gels revealed proteins adsorbed on aHAp, including secreted frizzled-related protein 3 and vitamin K epoxide reductase complex 1, which are involved in cellular bone differentiation. Overall, these proteins are expected to promote bone differentiation, representing a characteristic property of aHAp.

Magnesium-Rich Calcium Phosphate Derived from Tilapia Bone Has Superior Osteogenic Potential.

We extracted magnesium-rich calcium phosphate bioceramics from tilapia bone using a gradient thermal treatment approach and investigated their chemical and physicochemical properties. X-ray diffraction showed that tilapia fish bone-derived hydroxyapatite (FHA) was generated through the first stage of thermal processing at 600-800 °C. Using FHA as a precursor, fish bone biphasic calcium phosphate (FBCP) was produced after the second stage of thermal processing at 900-1200 °C. The beta-tricalcium phosphate content in the FBCP increased with an increasing calcination temperature. The fact that the lattice spacing of the FHA and FBCP was smaller than that of commercial hydroxyapatite (CHA) suggests that Mg-substituted calcium phosphate was produced via the gradient thermal treatment. Both the FHA and FBCP contained considerable quantities of magnesium, with the FHA having a higher concentration. In addition, the FHA and FBCP, particularly the FBCP, degraded faster than the CHA. After one day of degradation, both the FHA and FBCP released Mg2+, with cumulative amounts of 4.38 mg/L and 0.58 mg/L, respectively. Furthermore, the FHA and FBCP demonstrated superior bone-like apatite formation; they are non-toxic and exhibit better osteoconductive activity than the CHA. In light of our findings, bioceramics originating from tilapia bone appear to be promising in biomedical applications such as fabricating tissue engineering scaffolds.

Digital light processing of high-strength hydroxyapatite ceramics: Role of particle size and printing parameters on microstructural defects and mechanical properties

Dense hydroxyapatite (HA) bars were fabricated using digital light processing. The roles of HA median particle size (MPS), curing depth-to-layer thickness ratio (CD/LT), and debinding process on the printing/debinding flaws and flexural strength of the sintered parts were investigated. Commercial HA was milled for different times to provide powders with an MPS ranging from 0.3 to 2.7 µm. Thermal debinding led to delamination and vertical cracks, which decreased with increasing MPS; the minimum value required to fabricate specimens with appreciable flexural strength was 0.9 µm. At a given MPS (2.7 µm), the CD/LT varied between 1.4 and 3.3, indicating a progressive disappearance of the above major flaws. Finally, the positive effect of water debinding prior to thermal debinding on reducing crack formation was demonstrated. After optimisation, the bars achieved a flexural strength greater than 100 MPa, which is the highest value among dense HA fabricated using lithography-based techniques.

Clindamycin-Loaded Nanosized Calcium Phosphates Powders as a Carrier of Active Substances.

Bioactive calcium phosphate ceramics (CaPs) are one of the building components of the inorganic part of bones. Synthetic CaPs are frequently used as materials for filling bone defects in the form of pastes or composites; however, their porous structure allows modification with active substances and, thus, subsequent use as a drug carrier for the controlled release of active substances. In this study, four different ceramic powders were compared: commercial hydroxyapatite (HA), TCP, brushite, as well as HA obtained by wet precipitation methods. The ceramic powders were subjected to physicochemical analysis, including FTIR, XRD, and determination of Ca/P molar ratio or porosity. These techniques confirmed that the materials were phase-pure, and the molar ratios of calcium and phosphorus elements were in accordance with the literature. This confirmed the validity of the selected synthesis methods. CaPs were then modified with the antibiotic clindamycin. Drug release was determined on HPLC, and antimicrobial properties were tested against Staphylococcus aureus. The specific surface area of the ceramic has been demonstrated to be a factor in drug release efficiency.

Salt sensitive purely zwitterionic physical hydrogel for prevention of postoperative tissue adhesion.

Abdominal adhesions are a class of serious complications following abdominal surgery, resulting in a complicated and severe syndrome and sometimes leading to a Gordian knot. Traditional therapies employ hydrogels synthesized using complicated chemical formulations-often with click chemistry or thermal responsive hydrogel. The complicated synthesis process and severe conditions limit the extent of the hydrogels' applications. In this work, poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) polymer was synthesized to self-assemble into physical hydrogels due to the inter- and intramolecular ion interactions. The strong static interaction bonding density has a substantial impact on the gelation and physicochemical properties, which is beneficial to clinical applications and offers a novel way to obtain the desired hydrogel for a specific biomedical application. Intriguingly, this PSBMA polymer can be customized into a transient network with outstanding antifouling capability depending on the ion concentration. As ion concentration increases, the PSBMA hydrogel dissociated completely, endowing it as a candidate for adhesion prevention. In the cecum-sidewall model, the PSBMA hydrogel demonstrated superior anti-adhesion properties than commercial HA hydrogel. Furthermore, we have demonstrated that this PSBMA hydrogel could inhibit the inflammatory response and encourage anti-fibrosis resulting in adhesion prevention. Most surprisingly, the recovered skins of cecum and sidewall are as smooth as the control skin without any scar and damage. In conclusion, a practical hydrogel was synthesized using a facile method based on purely zwitterionic materials, and this ion-sensitive, antifouling adjustable supramolecular hydrogel with great clinic transform potential is a promising barrier for preventing postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: The development of hydrogels with satisfactory coverage, long retention time, facile synthetic method, and good biocompatibility is vital for preventing peritoneal adhesions. Herein, we developed a salt sensitive purely zwitterionic physical hydrogel poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) hydrogel to effectively prevent postoperative and recurrent abdominal adhesions. The hydrogel was simple to synthesize and easy to use. In the cecum-sidewall model, PSBMA hydrogel could instantaneously adhere and fix on irregular surfaces and stay in the wound for more than 10 days. The PSBMA hydrogel could inhibit the inflammatory response, encourage anti-fibrosis, and restore smoothness to damaged surfaces resulting in adhesion prevention. Overall, the PSBMA hydrogel is a promising candidate for the next generation of anti-adhesion materials to meet clinical needs.

Improvement in Bioactivity Properties of Hydroxyapatite Coated Ti-6Al-4V ELI with Addition of Zirconium Oxide for Orthopaedic Implant

One of factor causing the failure of Ti-6Al-4V Extra Low Interstitial (ELI)-based material implants, does not have bioactive properties in the implantation process, thus not supporting the osseointegration process in the body. For this reason, coating with hydroxyapatite (HA) suspension is necessary. This research used the dip-coating method and added Zirconium Oxide (ZrO2) into nanosized commercial HA to be suspensions (17%wt and 20%wt) to strengthen the adhesion of the coating. The specimens were heated at 800, 900, and 950°C to densify the layers. Bioactivity increased along with the increasing calcium/phosphate (Ca/P) ratio of the HA layers in the test specimens. The specimens were immersed in Simulated Body Fluid (SBF), namely Hank’s Solution, for 1, 2, 3, and 4 weeks. ZrO2 added to the HA suspensions of Ti-6Al-4V ELI can increase the Ca/P ratio from 1.51 in the first immersion week to 1.62 in the fourth. The bioactivity level is also proven by the accumulation of calcium and phosphate on the surface of the coating. The Ca/P value close to the Ca/P ratio of HA of 1.67 is good for improving the osseointegration process in the body.

In vitro evaluation of viscosity of facial hyaluronic acid fillers through shear tension analysis. Preliminary data

To analyze and describe the viscosity and the stress in relation to the shear rate of eleven facial fillers of four commercial HA brands with authorized use in Brazil through the flow sweep rheological analysis method. The rheological parameter of viscosity (η) was analyzed by rheometry tests through flow sweep. The behavior of shear stress showed that Rennova Fill Lido® and Lift Lido® have higher viscosity ratios (ƞ = 336 Pa.s and ƞ = 406 Pa.s, respectively). In contrast, Hialurox® brand fillers showed the lowest viscosity value (ƞ) (Hialurox Ultra Soft 8 mg/g® ƞ= 9 Pa.s, Fine 16 mg/g ƞ= 29 Pa.s, Fill 24 mg/g ƞ= 36 Pa.s, Lift 26 mg/g ƞ= 50 Pa.s). The flow sweep showed variations in the viscosity (ƞ) of the eleven HA dermal fillers. Rennova Fill Lido® and Lift Lido® have a lower degree of spreadability and are less susceptible to shear forces and yield strength, making them ideal candidates for the intended treatment.

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.