Hydroxyapatite Nanopowders Research Articles

Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions.

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr2+ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr2+ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr2+ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr2+ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr2+ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr2+ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr2+ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.

Mechanical Properties of Hydroxyapatite Ceramic Prepared from Micropowder and Nanopowder

In this work, hydroxyapatite ceramics were prepared from hydroxyapatite micropowder and nanopowder. The hydroxyapatite nanopowder was obtained from natural buffalo bone by using a high speed vibro-milling machine for 2 hour. The green compacted pellets of all HA powders were subsequently sintered at 1200, 1250, 1300 and 1350°C for 3 hour and then the physical and mechanical characterizations as well as microstructural evaluation have been carried out. It was found that the optimum sintering temperature were 1250°C by fabricated from nanopowder which gave the HA nanoceramic with the maximum bending strength of 78.6±2.6 MPa. This is about 200% higher than that of the sample which fabricated from HA micropowder.

Preparation and Characterization of Hydroxyapatite Nanopowder from Natural Buffalo Bone

The preparation of hydroxyapatite nanopowders in this experiment demonstrated a novel method for milling of animal bone powder to nanoparticle size prior to calcination. The buffalo bone was deproteinized by hot water before it was dried at 200°C for 24 h. The resulting product was crushed into small pieces and milled in a ball mill pot for 24 h. After that, the bone powders were ground by a high speed vibro-milling method with various milling times. Characteristics of the powders were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The experimental results of SEM showed that the shape of the buffalo bone particles was regular with the particle size less than 100 nm from using high speed vibro-milling time of 2 h. The buffalo bone nanopowder were calcined at various temperatures. XRD and SEM results showed that material obtained is a HA according to JCPDS file-9432 pattern in a 1.66 Ca/P molar ratio at calcination temperature of 600°C. The average diameter of powder less than 100 nm.

Microbial biomineralization of hydroxyapatite nanocrystals using Bacillus tequilensis

In this research, biomimetic deposition of “bone-like” apatite by novel Gram-positive bacterium Bacillus tequilensis was investigated. Hydroxyapatite (HA) was produced by Bacillus tequilensis using defined biomineralization media and dried. Calcination was carried out at different temperatures (100 °C–900 °C) and HA nanopowder was analysed for its structural phase composition, crystallinity, crystallite size and functional groups. X-ray diffractometry (XRD) indicated that increasing temperatures increased the crystallinity of HA nanocrystals. The presence of carbonate groups was evidenced by Fourier transform infrared (FTIR) spectrum and the purity of synthesized apatite nanocrystals was validated by absence of secondary peaks in XRD studies. Scanning electron microscopy (SEM) images depicted those uniform spherical agglomerates of HA comprised of nanosized crystallites. Transmission electron microscope (TEM) results identified needle-like crystal morphologies with average dimensions of 30–60 nm length and 3–10 nm width. Rich trace ion deposition was illustrated by energy dispersive x-ray spectroscopy (EDS) and quantified using inductively coupled plasma optical emission spectrometer (ICP-OES). Overall, microbial biomineralization by Bacillus tequilensis produced nanocrystals of HA that mimicked “bone-like apatite” as evidenced by pure phase, B-type carbonated form, poor crystallinity and trace amounts of vital elements (Mg, Na, K, Zn, Sr, Cl). Moreover, in vitro cytotoxicity studies revealed more than 80% cell viability highlighting the biocompatible nature of synthesized nano HA. Thereby, Bacillus tequilensis biomineralized nano HA reflects as a suitable candidate for applications in biomedicine addressing bone injuries and aiding regeneration.

3D Printed Composite Scaffolds of GelMA and Hydroxyapatite Nanopowders Doped with Mg/Zn Ions to Evaluate the Expression of Genes and Proteins of Osteogenic Markers.

As bone diseases and defects are constantly increasing, the improvement of bone regeneration techniques is constantly evolving. The main purpose of this scientific study was to obtain and investigate biomaterials that can be used in tissue engineering. In this respect, nanocomposite inks of GelMA modified with hydroxyapatite (HA) substituted with Mg and Zn were developed. Using a 3D bioprinting technique, scaffolds with varying shapes and dimensions were obtained. The following analyses were used in order to study the nanocomposite materials and scaffolds obtained by the 3D printing technique: Fourier transform infrared spectrometry and X-ray diffraction (XRD), scanning electron microscopy (SEM), and micro-computed tomography (Micro-CT). The swelling and dissolvability of each scaffold were also studied. Biological studies, osteopontin (OPN), and osterix (OSX) gene expression evaluations were confirmed at the protein levels, using immunofluorescence coupled with confocal microscopy. These findings suggest the positive effect of magnesium and zinc on the osteogenic differentiation process. OSX fluorescent staining also confirmed the capacity of GelMA-HM5 and GelMA-HZ5 to support osteogenesis, especially of the magnesium enriched scaffold.

Effect of Zn-nanoHA concentration on the mechanical performance and bioactivity of 3D printed PEEK composites for craniofacial implants

ABSTRACT This study aims to investigate the mechanical performance and bioactive potential of polyetheretherketone (PEEK)-based composites. PEEK powder is mixed with up to 20 wt-% zinc doped nano-hydroxyapatite (ZnHA) powder to extrude filaments. Subsequently, 3D-printed samples are prepared via fused deposition modelling (FDM). Micro-Computed Tomography (µ-CT) analysis shows the distribution of ZnHA particles in extruded filaments. Fourier transform infrared spectroscopy (FTIR) confirms the functional groups in 3D-printed samples. The tensile testing results showed that at higher concentration of ZnHA, the strength and strain at failure decrease, while the elastic modulus increases within the acceptable range of human cortical bone. Bioactivity tests in simulated body fluid (SBF) for up to 14 days illustrate the formation of apatite precipitates on the composite samples’ surface compared to pure PEEK. Based on the results, it can be concluded that FDM 3D-printing of PEEK/ZnHA composites can be used effectively in manufacturing customised craniofacial/orthopedic implants.

Mechanochemical synthesis and cold sintering of mussel shell-derived hydroxyapatite nano-powders for bone tissue regeneration

According to the circular economy principles, processing routes aiming at reducing the natural resources consumption and the energy demand can be addressed as ‘green’. In this framework, mussel shells, a natural feedstock of calcium carbonate, were successfully transformed into nano-crystalline hydroxyapatite by mechanochemical synthesis at room temperature after mixing with a phosphoric acid solution. The as-synthesized powder was then consolidated up to 82 % relative density by cold sintering (600 MPa, 200 °C). The materials were fully investigated by physical, chemical and thermal characterization techniques. Cold-sintered samples were also subjected to biaxial flexural strength test, showing a flexural resistance of 23 MPa. Cell viability assessment revealed that cold sintered hydroxyapatite derived from mussel shells promotes faster adhesion and spreading of human bone marrow-derived mesenchymal stem cells, in comparison to a commercial hydroxyapatite sintered at 1050 °C. Therefore, cold-sintered mussel shells-derived hydroxyapatite can be a promising future candidate scaffold for bone tissue regeneration.

Healing Assessment of Osseous Defects after Surgical Removal of Periapical Lesions in the Presence of Hydroxyapatite, Nanohydroxyapatite, and a Combination of Nanohydroxyapatite and Platelet-rich Fibrin: A Clinical Study

Abstract: Aim: to evaluate the bone healing in failed endodontically treated teeth after surgical removal of periapical lesions and placement of hydroxyapatite (HA), nanohydroxyapatite (nHA) and a combination of nanohydroxyapatite with platelet rich fibrin (PRF) periapically. Subjects and methods: the study was conducted on twenty-four patients having periapical radiolucency in single rooted teeth. The selected teeth were divided into three groups: Group A, Group B, and Group C; of 8 teeth each. All the teeth were retreated in two visits. In the first visit the old filling was removed using Protaper retreatment files (Dentsply Sirona®) then irrigation with sodium hypochlorite 2.5% was done. All canals were dried and filled with Di-antibiotic paste (metronidazole and ciprofloxacin). In the second visit the canals were obturated with Pro Taper gutta-percha points and root canal sealer (Adseal resin sealer) followed by surgical intervention in the same day. A periapical curettage along with apicoectomy were established. In all the groups, root end cavity was prepared and filled with MTA (ProRoot MTA; DENTSPLY Tulsa Dental Specialties). In Group A, hydroxyapatite powder was packed in the curetted periapical defect. In Group B, nanohydroxyapatite powder was packed in the curetted periapical defect. In Group C, nanohydroxyapatite with PRF were mixed and packed in the curetted periapical defect. In all groups, patients recall visits were scheduled at 1, 3, and 6 months’ time intervals for clinical and radiological evaluation. Results: after one month; there was a statistically significant difference between the median percentage changes in lesions size in the three groups. Pair-wise comparisons between groups revealed that there was no statistically significant difference between group B (nHA) and group C (PRF and nHA) groups. Both showed statistically significantly higher median percentage reduction in lesions size than group A (HA group). After three as well as six months; there was no statistically significant difference between the median percentage decreases in lesions size in the three groups. Conclusion: It was concluded that nHA combination with PRF produced faster periapical healing (bone regeneration) in the first three months than nHA alone. However, HA produce periapical healing (bone regeneration) after six months.

Noncytotoxic zinc-doped nanohydroxyapatite-based bone scaffolds with strong bactericidal, bacteriostatic, and antibiofilm activity.

Development of bone scaffolds that are nontoxic to eukaryotic cells, while revealing bactericidal activity still remains a huge challenge for the scientific community. It should be noted that only bacteriostatic (the ability of the biomaterial to inhibit the growth of bacteria) and bactericidal (the ability to kill >99.9% bacteria) activities have clinical importance. Unfortunately, many material scientists are confused with the microbiological definition of antibacterial action and consider biomaterials causing reduction in colony-forming units (CFUs) by 50-80% as promising antibacterial implants. The aim of this study was to synthesize three variants of Zn-doped hydroxyapatite (HA) nanopowder, which were characterized by different content of Zn2+ and served as a powder phase for the production of novel macroporous chitosan/agarose/nanoHA biomaterials with high antibacterial activity. Within this study, it was proven that the scaffold with a low zinc content (doping level 0.03mol for 1mol of HA; 0.2wt%) revealed the gradual and slow release of the Zn2+ ions, preventing against accumulation of high and toxic concentration of therapeutic agents and providing prolonged antibacterial activity. Moreover, developed biomaterial was nontoxic to human osteoblasts and showed anti-biofilm properties, bactericidal activity (> 99.9% of bacteria killed) against Staphylococcus epidermidis and Escherichia coli, significant antibacterial activity against Staphylococcus aureus (98.5% of bacteria killed), and also bacteriostatic activity against Pseudomonas aeruginosa. Thus, the developed Zn-doped HA-based bone scaffold has excellent antibacterial properties without toxicity against eukaryotic cells, being a promising biomaterial for biomedical applications to repair bone defects and prevent post-surgery infections.

Hydroxyapatite from Natural Sources for Medical Applications.

The aim of this work is to study the physical-chemical, mechanical, and biocompatible properties of hydroxyapatite obtained by hydrothermal synthesis, at relatively low temperatures and high pressures, starting from natural sources (Rapana whelk shells), knowing that these properties influence the behavior of nanostructured materials in cells or tissues. Thus, hydroxyapatite nanopowders were characterized by chemical analysis, Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In vitro studies on osteoblast cell lines (cytotoxicity and cell proliferation), as well as preliminary mechanical tests, have been performed. The results showed that the obtained powders have a crystallite size below 50 nm and particle size less than 100 nm, demonstrating that hydrothermal synthesis led to hydroxyapatite nanocrystalline powders, with a Ca:P ratio close to the stoichiometric ratio and a controlled morphology (spherical particle aggregates). The tensile strength of HAp samples sintered at 1100 °C/90 min varies between 37.6–39.1 N/mm2. HAp samples sintered at 1300 °C/120 min provide better results for the investigated mechanical properties. The coefficient of friction has an appropriate value for biomechanical applications. The results of cell viability showed that the cytotoxic effect is low for all tested samples. Better cell proliferation is observed for osteoblasts grown on square samples.

Physicochemical properties, acute and subchronic toxicity of nano-hydroxyapatite obtained from Lates calcarifer fish bone

As the main component of bones and teeth, hydroxyapatite (HAp) is considered a vital biomaterial in many fields. Meanwhile, fishbone by-products were used as abundant and cheap sources of natural HAp. The preparation of nano-HAp from fish bones not only contributes to increasing the value of by-products but also minimizes negative impacts on the environment. In this study, nano-HAp was successfully obtained from Lates calcarifer fish bone by the thermal calcination method. Analysis of SEM, TEM showed that the HAp nanopowders possessed an average size of 39.42 nm. The Ca/P molar ratio of 1.845 indicated that the nano-HAp powders were B-type biological hydroxyapatites, which has been confirmed by FTIR spectrum. In addition, the content of heavy metals including As, Pb, Hg, Cd and the microbial contamination are within safety limits of regulatory requirements of Vietnam regulation and US Pharmacopeia for food and dietary supplement standard. The other elements such as Fe, K, Mg, Na, Se, Zn are also present in nano-HAp. The investigation of acute toxicity shows that nano-HAp did not exhibit toxicity in Swiss mice at the highest dose of 6000 mg/kg body weight. The results of subchronic oral toxicity testing indicated that nano-HAP did not affect the behavior, body weight and hematological parameters of rabbits at doses of 50 and 100 mg/kg body weight for 28 days. The liver function indices (AST, ALT, GGT) and kidney function index (creatinine) are within normal limits. These properties suggest that nano-HAp from Lates calcarifer fish bones can be used as material in food and medicine fields.

The effect of nano and micro hydroxyapatite powder additives on surface integrity in electrical discharge machining of Ti6Al4V alloy

The current study investigates the Hydroxyapatite (HA) deposition phenomena to the modified surface of titanium (Ti) alloy in Hydroxyapatite Powder Mixed Electrical Discharge Machining (HA-PMEDM). Nano and micro size HA powders were mixed into the dielectric liquid and tested for a wide range of pulse currents and pulse-on durations. The change of surface and subsurface properties were evaluated in terms of Surface Roughness (SR), Optical and Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), and X-ray Diffraction (XRD). Finally, in-depth microhardness measurements were carried out to reveal the microhardness profile of the analyzed samples. As a result of the analysis, the effects of the process parameters on the surface roughness, surface topography, and powder deposition to the surface were evaluated. The current results reveal nano and micro powder additives deposited to the surface at different parameters during EDM. The highest rate of HA deposition to the machined surface observed when using 22 A pulse current and 100 μs pulse-on duration in micro additive dielectric liquid. Resolidified Layer (RL) and Heat Affected Layer (HAL) thicknesses vary between 5 and 50 μm, 8–83 μm respectively. Generaly, layer thicknesses in nano HA-PMEDM are higher than the micro HA-PMEDM. The hardness values of the samples machined in nano HA-PMEDM reach 1800 HV on RL. The current results support the use of HA-PMEDM to obtain functional surfaces for medical applications.

Synergic role of zinc and gallium doping in hydroxyapatite nanoparticles to improve osteogenesis and antibacterial activity

Recently, postoperative bone infections have been one of the most crucial challenges for surgeons. This study aims to synergistically promote antibacterial and osteoconductive properties of hydroxyapatite (HAp) nanoparticles through binary doping of Zn2+ and Ga3+ ions (Zn-Ga:HAp). Zn-Ga:HAp nanopowders with spherical morphology and homogeneous size are synthesized using a simple sol-gel method. Substitution of both zinc and gallium in the structure of HAp results in a gradual decrease in the lattice parameters as doping level increases, limits the growth of HAp particles and reduces its crystallinity. Noticeably, the crystallinity of HAp (85%) reduces to less than 73% (for XZn = 0.1), 78% (for XGa = 0.4) and 75% (for XZn = 0.1 and XGa = 0.4). Ion doping also significantly modulate the release of bioactive ions (Ca2+, PO43−, Zn2+, Ga3+) from the Zn-Ga:HAp depended on the overall amount of Ga and Zn in the HAp, which could mediate the biological responses. Incorporating both Zn2+ and Ga3+ ions in HAp structure could significantly improve the antibacterial activity of HAp nanopowders against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with a concentration-dependent effect. Noticeably, Zn-Ga:HAp (XZn = 0.1 and XGa = 0.4) powder shows the antibacterial activity of more than 68% and 84% against E. coli and S. aureus, respectively, at the concentration of 500 μg/ml, thereby showing excellent antibacterial properties. In addition, Zn-Ga:HAp nanopowders not only do not exhibit any cytotoxicity towards hMSCs, but also show significantly superior osteogenic properties. For instance, Zn-Ga:HAp (XZn = 0.1 and XGa = 0.4) nanopowders significantly enhance the alkaline phosphatase activity (approximately 2-fold) and mineralization (approximately 3-fold) of hMSCs after 14 days of culture, compared to pure HAp. Overall, Zn-Ga:HAp (XZn = 0.1 and XGa = 0.4) with desired osteogenesis and antibacterial activity compared to pure HAp, Zn:HAp and Ga:HAp shows promising opportunities for the implant-associated infections and the efficient healing of bone defects.

Cationic and Anionic Substitutions in the Antibacterial and Biocompatibility Properties of Sol-Gel Derived Hydroxyapatite Nanocomposites

This paper deals the synthesis and characterization of Pure Hydroxyapatite (Pure HAp) nanopowderan its nanocomposites. Hydroxyapatite - Zinc (HAp-Zn), Hydroxyapatite - Manganese (HAp-Mn) Hydroxyapatite - Titanium (HAp-Ti) and Hydroxyapatite - reduced Graphene oxide (HAp-rGO). The impact of Zn, Mn, Ti and rGO on the underlying, morphological, antimicrobial property and biocompatibility of hydroxyapatite nanopowders are contemplated. The structural characterization analysed through XRD. Pure HAp, HAp-Ti and HAp-rGO displayed hexagonal structure and fuse of Zn and Mn in the host lattice changed the construction into orthorhombic and rhombohedral. The normal crystallite size goes from 51 nm to 37 nm for different nanocomposites. The consolidation of cations (Zn2+ Mn2+ and Ti4+) and anion (CO3 2- ) diminished the crystallite size. Blended nanocomposites has hexagonal construction though there is hexagonal to orthorhombic progress in HAp-Zn and hexagonal to rhombohedral change in HAp-Mn nanocomposites The presence of functional groups in the samples is investigated utilizing FTIR examination. Surface morphology and compound organizations are examined utilizing Scanning Electron Microscope (SEM) and Energy Dispersive X-beam investigation (EDX) individually. The in-vitro antibacterial exercises and biocompatibility of the combined hydroxyapatite and its nanocomposite are examined utilizing Kirby-Bauer antibacterial testing and MTT assay individually. The outcomes show that Titanium and reduced Graphene Oxide fused hydroxyaptite nanocomposites are more harmful against every bacterial strain and didn't show any harmfulness against living tissues.

Structural, thermal and in-vitro analysis of sol-gel derived zinc and fluorine co-substituted nanodimensional hydroxyapatite for biomedical applications

Hydroxyapatite (HA) is widely used as a bone and dental substitute material due to its biocompatible and bioactive nature. Improvements in HA can be achieved by substituting various ions that are present in the bone. The present study of co-substitution of Zinc and Fluorine in HA was intended to investigate the influence of substituent ions on the structural, thermal, and bioactive behavior of HA. The co-substituted hydroxyapatite nanopowder was synthesized by water-based sol-gel method. Characterization studies from XRD, FTIR and TEM confirmed the substitution of Zn and F ions in HA and the formation of nanorods. The thermal stability of as-synthesized nanopowder was assessed by calcining it at three different temperatures i.e. 800 °C, 1000 °C and 1200 °C. The bioactivity of as-synthesized and calcined nanopowders was assessed by measuring the change in pH of simulated body fluid (SBF) and FTIR spectra after immersion in SBF for 30 days. The results revealed the bioactive behavior of as-synthesized and calcined nanopowders.

Development and characterization of acicular nano-hydroxyapatite powder from wet chemical synthesis method

Hydroxyapatite (HA) is a bioceramic material widely used in medical applications. Due to the high bioactivity and ability to promote better cell activities in the biological environment, HA is used in drug delivery applications and implants development applications. HA can be prepared by several synthetic routes and by using natural resources. In the present work, HA was produced from wet chemical synthesis method. The produced HA was characterized by electron microscopy to study the morphology and size of the HA crystals. X-ray diffraction studies have been carried out to analyze the produced HA. Then the powder was heated to 1000 °C to verify the level of purity. After heating to 1000 °C, from the XRD analysis, no appearance of new peaks corresponding to any other phase except HA confirms the level of purity of synthesized HA. The results demonstrate a simple and potential route to synthesize nano-HA. The produced nano-crystals were identified with acicular morphology with an average size of ∼100. The demonstrated simple route helps to produce economically nano-HA which can be used for drug delivery carrier and biomaterials applications.

Applying nano-HA in addition to scaling and root planing increases clinical attachment gain

PurposeThis study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP).MethodsA total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque.ResultsFrom baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05).ConclusionsApplying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

In vitro biocompatiability and mechanical properties of bone adhesive tape composite based on poly(butyl fumarate)/poly(propylene fumarate)-diacrylate networks

Polyfumarate has been considered as injectable and biodegradable bone cement. However, its mechanical and degradation properties are particularly important. Therefore, the current study aimed to develop the properties by compositing poly (butyl fumarate)-based networks with hydroxyapatite nano-powders. In this regard, the poly (butyl fumarate) (PBF) matrix composite was compared with different components by evaluating their composition, mechanical properties, hydrophilicity, and biodegradability. Furthermore, their bioactivity in the phosphate-buffered saline (PBS) and, via applying mouse embryo osteoblast precursor cells (MC3T3-E1), their cell interaction, including adhesion, proliferation, and in vitro cytotoxicity assay, were assessed. The addition of hydroxyapatite improved the mechanical strength and modulus of PBF matrix composite. The composite reinforced with 3 wt% hydroxyapatite showed a higher lap-shear strength (1.68 MPa) and bonding strength (4.30 MPa), a maximum compression strength at fracture (95.18 MPa), modulus (925.29 MPa), and compression strength at yield (31.43 MPa), respectively. Also, hydrophilicity and in vitro degradation of the composite were enhanced in the presence of hydroxyapatite. In this condition, after a period of immersion (52 weeks) in PBS, the weight loss rate, and degradation rate of the composite increased. The composite proliferation, adhesion, and toxicity of MC3T3-E1 cells improved in comparison to the PBF matrix composite. Accordingly, controllable strength and degradation of the composite, along with its proven biocompatibility, make the composite a candidate for the treatment of comminuted fractures.

Hydrothermal Microwave-Assisted Fabrication of Nanohydroxyapatite Powder and Optimization of Its Nanocomposite Coatings on Magnesium Alloy for Orthopedic Applications.

Developing appropriate protecting coatings for Mg alloy applications is a challenging issue. Herein, nanohydroxyapatite (nanoHAP) powder was first fabricated by the simple hydrothermal microwave-assisted method. A direct current electrophoresis deposition (EPD) of nanoHAP composite coatings on Mg–3Zn–0.8Ca magnesium alloy was successfully executed. Three suspensions with HAP-dispersive resin solution (ETELAC) ratios (in wt %) of 5–5, 5–2.5, and 2.5–2.5 were chosen for optimizing the effect of applied voltage, deposition time, and stirring mode and rates on the EPD process. NanoHAP composite coatings were applied on each sample in single- and double-run depositions. The results revealed that the maximum weight gain on the coated samples was obtained in 5–5 suspension at 50 V under 150 rpm mechanical stirring rate. Surface examination indicated crack-free coating formation with varying grain sizes. Adhesion tests demonstrated high interconnection between the obtained nanocomposite coatings and the alloy substrate. Electrochemical evaluation measurements in SBF at 37 °C indicated that the corrosion resistance of any coated sample is always superior compared to that of the uncoated bare substrate. It was suggested that the EPD of nanoHAP/ETELAC composite coatings on Mg–Zn–Ca alloy can be a good solution for protecting the alloy from the attack of the aggressive ions bound in the SBF environment.

Hydroxyapatite-decorated Fmoc-hydrogel as a bone-mimicking substrate for osteoclast differentiation and culture

Hydrogels are water-swollen networks with great potential for tissue engineering applications. However, their use in bone regeneration is often hampered due to a lack of materials’ mineralization and poor mechanical properties. Moreover, most studies are focused on osteoblasts (OBs) for bone formation, while osteoclasts (OCs), cells involved in bone resorption, are often overlooked. Yet, the role of OCs is pivotal for bone homeostasis and aberrant OC activity has been reported in several pathological diseases, such as osteoporosis and bone cancer. For these reasons, the aim of this work is to develop customised, reinforced hydrogels to be used as material platform to study cell function, cell-material interactions and ultimately to provide a substrate for OC differentiation and culture. Here, Fmoc-based RGD-functionalised peptide hydrogels have been modified with hydroxyapatite nanopowder (Hap) as nanofiller, to create nanocomposite hydrogels. Atomic force microscopy showed that Hap nanoparticles decorate the peptide nanofibres with a repeating pattern, resulting in stiffer hydrogels with improved mechanical properties compared to Hap- and RGD-free controls. Furthermore, these nanocomposites supported adhesion of Raw 264.7 macrophages and their differentiation in 2D to mature OCs, as defined by the adoption of a typical OC morphology (presence of an actin ring, multinucleation, and ruffled plasma membrane). Finally, after 7 days of culture OCs showed an increased expression of TRAP, a typical OC differentiation marker. Collectively, the results suggest that the Hap/Fmoc-RGD hydrogel has a potential for bone tissue engineering, as a 2D model to study impairment or upregulation of OC differentiation. Statement of significanceAltered osteoclasts (OC) function is one of the major cause of bone fracture in the most commonly skeletal disorders (e.g. osteoporosis). Peptide hydrogels can be used as a platform to mimic the bone microenvironment and provide a tool to assess OC differentiation and function. Moreover, hydrogels can incorporate different nanofillers to yield hybrid biomaterials with enhanced mechanical properties and improved cytocompatibility. Herein, Fmoc-based RGD-functionalised peptide hydrogels were decorated with hydroxyapatite (Hap) nanoparticles to generate a hydrogel with improved rheological properties. Furthermore, they are able to support osteoclastogenesis of Raw264.7 cells in vitro as confirmed by morphology changes and expression of OC-markers. Therefore, this Hap-decorated hydrogel can be used as a template to successfully differentiate OC and potentially study OC dysfunction.