Science.gov

Sample records for hydroxyapatite ha microspheres

  1. Biomimetic composite microspheres of collagen/chitosan/nano-hydroxyapatite: In-situ synthesis and characterization.

    PubMed

    Teng, Shu-Hua; Liang, Mian-Hui; Wang, Peng; Luo, Yong

    2016-01-01

    The collagen/chitosan/hydroxyapatite (COL/CS/HA) composite microspheres with a good spherical form and a high dispersity were successfully obtained using an in-situ synthesis method. The FT-IR and XRD results revealed that the inorganic phase in the microspheres was crystalline HA containing carbonate ions. The morphology of the composite microspheres was dependent on the HA content, and a more desirable morphology was achieved when 20 wt.% HA was contained. The composite microspheres exhibited a narrow particle distribution, most of which ranged from 5 to 10 μm. In addition, the needle-like HA nano-particles were uniformly distributed in the composite microspheres, and their crystallinity and crystal size decreased with the HA content.

  2. Scaffolds for bone regeneration made of hydroxyapatite microspheres in a collagen matrix.

    PubMed

    Cholas, Rahmatullah; Kunjalukkal Padmanabhan, Sanosh; Gervaso, Francesca; Udayan, Gayatri; Monaco, Graziana; Sannino, Alessandro; Licciulli, Antonio

    2016-06-01

    Biomimetic scaffolds with a structural and chemical composition similar to native bone tissue may be promising for bone tissue regeneration. In the present work hydroxyapatite mesoporous microspheres (mHA) were incorporated into collagen scaffolds containing an ordered interconnected macroporosity. The mHA were obtained by spray drying of a nano hydroxyapatite slurry prepared by the precipitation technique. X-ray diffraction (XRD) analysis revealed that the microspheres were composed only of hydroxyapatite (HA) phase, and energy-dispersive x-ray spectroscopy (EDS) analysis revealed the Ca/P ratio to be 1.69 which is near the value for pure HA. The obtained microspheres had an average diameter of 6 μm, a specific surface area of 40 m(2)/g as measured by Brunauer-Emmett-Teller (BET) analysis, and Barrett-Joyner-Halenda (BJH) analysis showed a mesoporous structure with an average pore diameter of 16 nm. Collagen/HA-microsphere (Col/mHA) composite scaffolds were prepared by freeze-drying followed by dehydrothermal crosslinking. SEM observations of Col/mHA scaffolds revealed HA microspheres embedded within a porous collagen matrix with a pore size ranging from a few microns up to 200 μm, which was also confirmed by histological staining of sections of paraffin embedded scaffolds. The compressive modulus of the composite scaffold at low and high strain values was 1.7 and 2.8 times, respectively, that of pure collagen scaffolds. Cell proliferation measured by the MTT assay showed more than a 3-fold increase in cell number within the scaffolds after 15 days of culture for both pure collagen scaffolds and Col/mHA composite scaffolds. Attractive properties of this composite scaffold include the potential to load the microspheres for drug delivery and the controllability of the pore structure at various length scales.

  3. Preparation of resorbable carbonate-substituted hollow hydroxyapatite microspheres and their evaluation in osseous defects in vivo

    PubMed Central

    Xiao, Wei; Bal, B. Sonny; Rahaman, Mohamed N.

    2015-01-01

    Hollow hydroxyapatite (HA) microspheres, with a high-surface-area mesoporous shell, can provide a unique bioactive and osteoconductive carrier for proteins to stimulate bone regeneration. However, synthetic HA has a slow resorption rate and a limited ability to remodel into bone. In the present study, hollow HA microspheres with controllable amounts of carbonate substitution (0–12 wt. %) were created using a novel glass conversion route and evaluated in vitro and in vivo. Hollow HA microspheres with ~12 wt. % of carbonate (designated CHA12) showed a higher surface area (236 m2g−1) than conventional hollow HA microspheres (179 m2g−1) and a faster degradation rate in a potassium acetate buffer solution. When implanted for 12 weeks in rat calvarial defects, the CHA12 and HA microspheres showed a limited capacity to regenerate bone but the CHA12 microspheres resorbed faster than the HA microspheres. Loading the microspheres with bone morphogenetic protein-2 (BMP2) (1 μg per defect) stimulated bone regeneration and accelerated resorption of the CHA12 microspheres. At 12 weeks, the amount of new bone in the defects implanted with the CHA12 microspheres (73 ± 8 %) was significantly higher than the HA microspheres (59 ± 2%) while the amount of residual CHA12 microspheres (7 ± 2% of the total defect area) was significantly lower than the HA microspheres (21 ± 3%). The combination of these carbonate-substituted HA microspheres with clinically safe doses of BMP2 could provide promising implants for healing non-loaded bone defects. PMID:26706537

  4. Preparation of resorbable carbonate-substituted hollow hydroxyapatite microspheres and their evaluation in osseous defects in vivo.

    PubMed

    Xiao, Wei; Bal, B Sonny; Rahaman, Mohamed N

    2016-03-01

    Hollow hydroxyapatite (HA) microspheres, with a high-surface-area mesoporous shell, can provide a unique bioactive and osteoconductive carrier for proteins to stimulate bone regeneration. However, synthetic HA has a slow resorption rate and a limited ability to remodel into bone. In the present study, hollow HA microspheres with controllable amounts of carbonate substitution (0-12 wt.%) were created using a novel glass conversion route and evaluated in vitro and in vivo. Hollow HA microspheres with ~12 wt.% of carbonate (designated CHA12) showed a higher surface area (236 m(2) g(-1)) than conventional hollow HA microspheres (179 m(2)g(-1)) and a faster degradation rate in a potassium acetate buffer solution. When implanted for 12 weeks in rat calvarial defects, the CHA12 and HA microspheres showed a limited capacity to regenerate bone but the CHA12 microspheres resorbed faster than the HA microspheres. Loading the microspheres with bone morphogenetic protein-2 (BMP2) (1 μg per defect) stimulated bone regeneration and accelerated resorption of the CHA12 microspheres. At 12 weeks, the amount of new bone in the defects implanted with the CHA12 microspheres (73±8%) was significantly higher than the HA microspheres (59±2%) while the amount of residual CHA12 microspheres (7±2% of the total defect area) was significantly lower than the HA microspheres (21±3%). The combination of these carbonate-substituted HA microspheres with clinically safe doses of BMP2 could provide promising implants for healing non-loaded bone defects.

  5. Polymer assisted hydroxyapatite microspheres suitable for biomedical application.

    PubMed

    Sinha, A; Mishra, T; Ravishankar, N

    2008-05-01

    Hollow Microspheres of hydroxyapatite-polymer composite can be used as carriers in drug delivery and fillers in tissue engineering. Based on the concept of soft chemistry, a battery of technique is available in the literature to synthesize hollow microspheres, however, an economically viable synthesis route, having good control over the microarchitect and easy to be scaled up, is yet to be developed. Polymer matrix mediated synthesis of inorganic nanoparticles is known to synthesize nanoparticles with controlled morphology and dimensions. It is termed as biomimetic synthesis. Integrating the biomimetic synthesis of nano-particles and spray drying techniques, a novel process of producing hydroxyapatite-polymer composite hollow microspheres is briefly discussed here.

  6. Preparation and characterization of gelatin-hydroxyapatite composite microspheres for hard tissue repair.

    PubMed

    Chao, Shao Ching; Wang, Ming-Jia; Pai, Nai-Su; Yen, Shiow-Kang

    2015-12-01

    Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending. The cell culture indicates that G-HA composite microspheres without any toxicity could enhance the proliferation and differentiation of osteoblast-like cells. In a rat calvarial defect model, G-HA bioactive scaffolds were compared with fibrin glue (F) and Osteoset® Bone Graft Substitute (OS) for their capacity of regenerating bone. Four weeks post-implantation, new bone, mineralization, and expanded blood vessel area were found in G-HA scaffolds, indicating greater osteoconductivity and bioactivity than F and OS.

  7. Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel

    PubMed Central

    Fu, Hailuo; Rahaman, Mohamed N.; Brown, Roger F.; Day, Delbert E.

    2013-01-01

    Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area, mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35–40% of the BSA initially loaded into the microspheres was released into PEG over ~14 days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases. PMID:23498254

  8. Hydroxyapatite (HA) bone scaffolds with controlled macrochannel pores.

    PubMed

    Bae, Chang-Jun; Kim, Hae-Won; Koh, Young-Hag; Kim, Hyoun-Ee

    2006-06-01

    Hydroxyapatite (HA) macrochanneled porous scaffolds, with a controlled pore structure, were fabricated via a combination of the extrusion and lamination processes. The scaffold was architectured by aligning and laminating the extruded HA and carbon filaments. The macrochannel pores were formed by removing the carbon filaments after thermal treatments (binder removal and sintering). The porosity of the scaffolds was varied between 48 and 73% with a controlled pore size of approximately 450 microm, by adjusting the fractions of HA and carbon filaments. As the porosity was increased from 48 to 73%, the compressive strength decreased from 11.5 to 3.2 MPa. However, the osteoblast-like cell responses on the scaffold, such as the proliferation rate and alkaline phosphatase (ALP) activity, were significantly enhanced as the porosity was increased.

  9. Spheroidized Hydroxyapatite (HA) Powders Plasma Spraying of Combustion Flame

    NASA Astrophysics Data System (ADS)

    Khor, K. A.; Wang, Y.; Cheang, P.

    1998-06-01

    Tailoring powder characteristics to suit the plasma spray process can alleviate difficulties associated with the preparation of hydroxyapatite (HA) coatings. Commercial HA feedstock normally exhibit an angular morphology and a wide particle size range that present difficulties in powder transport from the powder hopper to the plasma spray gun and in nonuniform melting of the powders in the plasma flame. Hence, combustion flame spheroidized hydroxyapatite (SHA) was used as the feedstock for plasma spraying. Spherical particles within a narrow particle size range are found to be more effective for the plasma spray processes. Results show coatings generated from spheroidized HA powders have unique surface and microstructure characteristics. Scanning electron microscope (SEM) observation of the coating surface revealed well-formed splats that spread and flatten into disc configurations with no disintegration, reflecting adequate melting of the HA in the plasma and subsequent deposition consistency. The surface topography is generally flat with good overlapping of subsequent spreading droplets. Porosity in the form of macropores is substantially reduced. The cross-section microstructure reveals a dense coating comprised of randomly stacked lamellae. The tensile bond strengths of the SHA coatings, phase composition, and characteristics of the coatings generated with different particle sizes (125 to 75 µm, 45 to 75 µm, 20 to 45 µm, and 5 to 20 µm) showed that a high bond strength of ˜16 MPa can be obtained with SHA in the size range from 20 to 45 µm. This can be improved further by a postspray treatment by hot isostatic pressing (HIP). However, larger particle size ranges exhibited higher degrees of crystallinity and relatively higher HA content among the various calcium phosphate phases found in the coatings.

  10. Biopolymers for Medical Applications: Polyglycerol Sebacate (PGS) doped Hydroxyapatite (HA)

    NASA Astrophysics Data System (ADS)

    Teruel, Maria; Kuthirummal, Narayanan; Levi, Nicole; Wake College Team

    2011-04-01

    In the investigation to engineer the ideal scaffolding device for cleft palate repair, polyglycerol sebacate (PGS) doped with hydroxyapatite (HA) were chosen for their elastomeric and biodegradable properties, as well as their cost-effective synthesis. Hydroxyapatite was integrated into the PGS to form a composite with high porosity and improved mechanical properties yielding a good substrate for cell attachment during the repair process. FT-IR scans were performed to characterize the composite polymer. Differential Scanning Calorimetry (DSC) was utilized to identify an acceptable glass transition temperature (Tg), between -18 and - 21°C. At this Tg, it was determined that the material was sufficiently polymerized to a point where it was durable yet pliable enough to use for cleft palate devices. In the synthesis of PGS 3% and 5% HA, a Tg of - 20.10°C and - 21.72°C, respectively, was achieved and further analytical tests were then performed on the polymers. Methods of analysis included X-Ray Diffraction and Tensile Strength Testing. Acknowledgements to the Research Department of Plastic and Reconstructive Surgery, Wake Forest University and College of Charleston.

  11. In vitro bioactivity of bioresorbable porous polymeric scaffolds incorporating hydroxyapatite microspheres.

    PubMed

    Li, L H; Kommareddy, K P; Pilz, C; Zhou, C R; Fratzl, P; Manjubala, I

    2010-07-01

    Biomimetic composites consisting of polymer and mineral components, resembling bone in structure and composition, were produced using a rapid prototyping technique for bone tissue engineering applications. Solid freeform fabrication, known as rapid prototyping (RP) technology, allows scaffolds to be designed with pre-defined and controlled external and internal architecture. Using the indirect RP technique, a three-component scaffold with a woodpile structure, consisting of poly-L-lactic acid (PLLA), chitosan and hydroxyapatite (HA) microspheres, was produced that had a macroporosity of more than 50% together with micropores induced by lyophilization. X-ray diffraction analysis indicated that the preparation and construction of the composite scaffold did not affect the phase composition of the HA. The compressive strength and elastic modulus (E) for the PLLA composites are 0.42 and 1.46 MPa, respectively, which are much higher than those of chitosan/HA composites and resemble the properties of cellular structure. These scaffolds showed excellent biocompatibility and ability for three-dimensional tissue growth of MC3T3-E1 pre-osteoblastic cells. The pre-osteoblastic cells cultured on these scaffolds formed a network on the HA microspheres and proliferated not only in the macropore channels but also in the micropores, as seen from the histological analysis and electron microscopy. The proliferating cells formed an extracellular matrix network and also differentiated into mature osteoblasts, as indicated by alkaline phosphatase enzyme activity. The properties of these scaffolds indicate that they can be used for non-load-bearing applications.

  12. Preparation of hollow hydroxyapatite microspheres by the conversion of borate glass at near room temperature

    SciTech Connect

    Yao, Aihua; Ai, Fanrong; Liu, Xin; Wang, Deping; Huang, Wenhai; Xu, Wei

    2010-01-15

    Hollow hydroxyapatite microspheres, consisting of a hollow core and a porous shell, were prepared by converting Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass microspheres in dilute phosphate solution at 37 {sup o}C. The results confirmed that Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass was transformed to hydroxyapatite without changing the external shape and dimension of the original glass object. Scanning electron microscopy images showed the shell wall of the microsphere was built from hydroxyapatite particles, and these particles spontaneously align with one another to form a porous sphere with an interior cavity. Increase in phosphate concentration resulted in an increase in the reaction rate, which in turn had an effect on shell wall structure of the hollow hydroxyapatite microsphere. For the Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass microspheres reacted in low-concentration K{sub 2}HPO{sub 4} solution, lower reaction rate and a multilayered microstructure were observed. On the other hand, the glass microspheres reacted in higher phosphate solution converted more rapidly and produced a single hydroxyapatite layer. Furthermore, the mechanism of forming hydroxyapatite hollow microsphere was described.

  13. Structure design and fabrication of porous hydroxyapatite microspheres for cell delivery

    NASA Astrophysics Data System (ADS)

    Li, Ruijing; Chen, Kexin; Li, Geng; Han, Guoxiang; Yu, Sheng; Yao, Juming; Cai, Yurong

    2016-09-01

    Porous microspheres fabricated from bioceramics have great potential for cell delivery in injectable tissue engineering application. The size and structure of pores in the microspheres are important for the effective protection and transportation of cells. In this study, porous hydroxyapatite microspheres are fabricated through the water-in-oil emulsion method followed by a calcination treatment at the high temperature. Both self-made resorcinol-formaldehyde (RF) composite spheres and camphene are used as pore-forming agents to produce big pores corresponding to the size of RF spheres and connected channel among big pores in hydroxyapatite matrix. The properties of the microspheres are characterized using X-ray diffraction, thermogravimetry analysis, universal material machine, field emission scanning electron microscopy. Cell assays are carried out to evaluate the cellular compatibility of the microspheres. The results showed that the hydroxyapatite microspheres with controllable pore structure and high porosity could be fabricated by this method, which have better strength to resist the compressive force. The microspheres are conducive to support adhesion, proliferation and differentiation of MC3T3-E1 cells. The results indicate that the obtained porous hydroxyapatite microspheres can be a permeable microenvironment for cell delivery in injectable tissue engineering.

  14. Effect of surface modified hydroxyapatite on the tensile property improvement of HA/PLA composite

    NASA Astrophysics Data System (ADS)

    Li, J.; Lu, X. L.; Zheng, Y. F.

    2008-11-01

    In this study, we modified the surface of hydroxyapatite (HA) particle by ring-opening polymerization of lactide (LA). The modified HA particles were characterized by IR and TGA. It was shown that LA could be graft-polymerized onto the surface of HA. A series of composites based on modified HA/PLA were further prepared and characterized. It indicated that the modified HA particles were well dispersed in PLA matrix than unmodified HA particles and the adhesion between HA particle and PLA matrix was improved. The modified HA/PLA composites showed good mechanical properties than that of unmodified HA/PLA.

  15. BMP2-loaded hollow hydroxyapatite microspheres exhibit enhanced osteoinduction and osteogenicity in large bone defects.

    PubMed

    Xiong, Long; Zeng, Jianhua; Yao, Aihua; Tu, Qiquan; Li, Jingtang; Yan, Liang; Tang, Zhiming

    2015-01-01

    The regeneration of large bone defects is an osteoinductive, osteoconductive, and osteogenic process that often requires a bone graft for support. Limitations associated with naturally autogenic or allogenic bone grafts have demonstrated the need for synthetic substitutes. The present study investigates the feasibility of using novel hollow hydroxyapatite microspheres as an osteoconductive matrix and a carrier for controlled local delivery of bone morphogenetic protein 2 (BMP2), a potent osteogenic inducer of bone regeneration. Hollow hydroxyapatite microspheres (100±25 μm) with a core (60±18 μm) and a mesoporous shell (180±42 m(2)/g surface area) were prepared by a glass conversion technique and loaded with recombinant human BMP2 (1 μg/mg). There was a gentle burst release of BMP2 from microspheres into the surrounding phosphate-buffered saline in vitro within the initial 48 hours, and continued at a low rate for over 40 days. In comparison with hollow hydroxyapatite microspheres without BMP2 or soluble BMP2 without a carrier, BMP2-loaded hollow hydroxyapatite microspheres had a significantly enhanced capacity to reconstitute radial bone defects in rabbit, as shown by increased serum alkaline phosphatase; quick and complete new bone formation within 12 weeks; and great biomechanical flexural strength. These results indicate that BMP2-loaded hollow hydroxyapatite microspheres could be a potential new option for bone graft substitutes in bone regeneration.

  16. BMP2-loaded hollow hydroxyapatite microspheres exhibit enhanced osteoinduction and osteogenicity in large bone defects

    PubMed Central

    Xiong, Long; Zeng, Jianhua; Yao, Aihua; Tu, Qiquan; Li, Jingtang; Yan, Liang; Tang, Zhiming

    2015-01-01

    The regeneration of large bone defects is an osteoinductive, osteoconductive, and osteogenic process that often requires a bone graft for support. Limitations associated with naturally autogenic or allogenic bone grafts have demonstrated the need for synthetic substitutes. The present study investigates the feasibility of using novel hollow hydroxyapatite microspheres as an osteoconductive matrix and a carrier for controlled local delivery of bone morphogenetic protein 2 (BMP2), a potent osteogenic inducer of bone regeneration. Hollow hydroxyapatite microspheres (100±25 μm) with a core (60±18 μm) and a mesoporous shell (180±42 m2/g surface area) were prepared by a glass conversion technique and loaded with recombinant human BMP2 (1 μg/mg). There was a gentle burst release of BMP2 from microspheres into the surrounding phosphate-buffered saline in vitro within the initial 48 hours, and continued at a low rate for over 40 days. In comparison with hollow hydroxyapatite microspheres without BMP2 or soluble BMP2 without a carrier, BMP2-loaded hollow hydroxyapatite microspheres had a significantly enhanced capacity to reconstitute radial bone defects in rabbit, as shown by increased serum alkaline phosphatase; quick and complete new bone formation within 12 weeks; and great biomechanical flexural strength. These results indicate that BMP2-loaded hollow hydroxyapatite microspheres could be a potential new option for bone graft substitutes in bone regeneration. PMID:25609957

  17. Immobilization of salvianolic acid B-loaded chitosan microspheres distributed three-dimensionally and homogeneously on the porous surface of hydroxyapatite scaffolds.

    PubMed

    Li, Jinyu; Wang, Qin; Zhi, Wei; Wang, Jianxin; Feng, Bo; Qu, Shuxin; Mu, Yandong; Weng, Jie

    2016-10-07

    Porous hydroxyapatite (HA) scaffolds combined with a drug delivery system have attracted much attention for bone tissue engineering. In this study, an easy and highly efficient method was developed to immobilize salvianolic acid B (Sal B)-loaded chitosan (CS) microspheres three dimensionally and homogeneously on the surface of HA scaffolds pre-coated with alginate. Porous HA scaffolds were prepared via a template-leaching process and CS microspheres (used as drug carriers) were fabricated by an emulsion method. To improve adhesion between the microspheres and HA scaffolds, alginate was used to pre-coat the porous surface of the HA scaffolds. Various concentrations of alginate were used to optimize the adhesion of Sal B-loaded CS microspheres to the scaffold surface. During the adherence process, coated HA scaffolds were immersed in an aqueous solution containing Sal B-loaded CS microspheres, followed by standing or shaking at 37 °C for a certain time. The results showed that the microspheres were solidly and homogeneously distributed on the porous surface of the alginate pre-coated HA scaffolds via electrostatic interactions. Few microspheres detached from the porous surface, even after the HA scaffolds with microspheres were treated by shaking in distilled water for as long as 7 d. Compared with the static condition, the distribution of Sal B-loaded CS microspheres on the porous surface of pre-coated HA scaffolds in the shaken condition was more homogeneous and almost unaggregated. Additionally, the compressive strength of the scaffolds coated with alginate was obviously improved. The optimal alginate coating concentration was 1% (i.e. the microstructure of the porous surfaces of the HA scaffolds was almost unchanged). The release profile of Sal B over a 30 d immersion found an initial burst release followed by a sustained release. The result of cell culture in vitro was that 1% alginate-coated scaffolds with Sal B-loaded CS microspheres obviously promoted cell

  18. Preparation of chitosan/nano hydroxyapatite organic-inorganic hybrid microspheres for bone repair.

    PubMed

    Chen, Jingdi; Pan, Panpan; Zhang, Yujue; Zhong, Shengnan; Zhang, Qiqing

    2015-10-01

    In this work, we encapsulated icariin (ICA) into chitosan (CS)/nano hydroxyapatite (nHAP) composite microspheres to form organic-inorganic hybrid microspheres for drug delivery carrier. The composition and morphology of composite microspheres were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry- thermogravimetric analysis (DSC-TGA). Moreover, we further studied the performance of swelling properties, degradation properties and drug release behavior of the microspheres. ICA, the extract of traditional Chinese medicine-epimedium, was combined to study drug release properties of the microspheres. ICA loaded microspheres take on a sustained release behavior, which can be not only ascribed to electrostatic interaction between reactive negative hydroxyl (OH) of ICA and positive amine groups (NH₂) of CS, but also depended on the homogeneous dispersion of HAP nanoparticles inside CS organic matrix. In addition, the adhesion and morphology of osteoblasts were detected by inverted fluorescence microscopy. The biocompatibility of CS/nHAP/ICA microspheres was evaluated by the MTT cytotoxicity assay, Hoechst 33258 and PI fluorescence staining. These studies demonstrate that composite microspheres provide a suitable microenvironment for osteoblast attachment and proliferation. It can be speculated that the ICA loaded CS-based organic-inorganic hybrid microspheres might have potential applications in drug delivery systems.

  19. [Preparation of elastic porous cell scaffold fabricated with combined polydimethylsiloxane (PDMS) and hydroxyapatite (HA)].

    PubMed

    Yang, Yang; Lan, Ding; Huang, Yan; Li, Yanming; Wang, Yuren; Sun, Lianwen; Fan, Yubo

    2014-06-01

    Polydimethylsiloxane (PDMS) and hydroxyapatite (HA) were combined in our laboratory to fabricate an elastic porous cell scaffold with pore-forming agent, and then the scaffold was used as culture media for rat bone marrow derived mesenchymal stem cells (rBMSCs). Different porous materials (square and circular in shape) were prepared by different pore-forming agents (NaCl or paraffin spheres) with adjustable porosity (62%-76%). The HA crystals grew on the wall of hole when the material was exposed to SBF solutions, showing its biocompatibility and ability to support the cells to attach on the materials.

  20. Biological and physico-chemical assessment of hydroxyapatite (HA) with different porosity.

    PubMed

    Hornez, J-C; Chai, F; Monchau, F; Blanchemain, N; Descamps, M; Hildebrand, H F

    2007-11-01

    HA with specific internal porosities was loaded with different antibiotics (ATBs) and then tested on its microbiological effectiveness. The HA purity was controlled with X-ray diffraction, IR and Raman spectrometry. Varying the sintering temperature and/or adding graphite and PMMA as porogenous agents lead to obtained micro- and meso-porosities. The biological tests concerned cell viability, proliferation and morphology (SEM), and the cytochemical staining of actin and vinculin. The micro- and meso-porous HA samples had an internal pore size of 1-10 microm and 10-50 microm, respectively. X-ray diffraction and FTIR confirmed the high purity of the HA. The cell viability tests with L132 cells confirmed the excellent cytocompatibility of HA, the graphite powder and the ATB vancomycine. Proliferation rate was assessed with MC3T3-E1 osteoblasts. All HA samples produced a higher proliferation than the controls; the micro-porous HA inducing the highest cell growth. The ATB impregnated HA also stimulated cell proliferation but in lower extend. Cytochemical staining of osteoblasts revealed a well-developed cytoskeleton with strong stress fibres. Labelling of the focal adhesion contacts with anti-vinculin showed a less developed adhesion process in the cells on the different HA substrates. It was possible to realize a highly pure hydroxyapatite with different but controlled porosities by varying the sintering temperature and/or addition of a porogenous agents. This purity and the micro-porosity stimulate significantly cell growth.

  1. Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

    PubMed

    Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

    2015-03-20

    Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

  2. Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates

    NASA Astrophysics Data System (ADS)

    Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

    2015-03-01

    Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

  3. Effects of Nano-hydroxyapatite/Poly(DL-lactic-co-glycolic acid) Microsphere-Based Composite Scaffolds on Repair of Bone Defects: Evaluating the Role of Nano-hydroxyapatite Content.

    PubMed

    He, Shu; Lin, Kai-Feng; Sun, Zhen; Song, Yue; Zhao, Yi-Nan; Wang, Zheng; Bi, Long; Liu, Jian

    2016-07-01

    The aim of the current study was to prepare microsphere-based composite scaffolds made of nano-hydroxyapatite (nHA)/poly (DL-lactic-co-glycolic acid) (PLGA) at different ratios and evaluate the effects of nHA on the characteristics of scaffolds for tissue engineering application. First, microsphere-based composite scaffolds made of two ratios of nHA/PLGA (nHA/PLGA = 20/80 and nHA/PLGA = 50/50) were prepared. Then, the effects of nHA on the wettability, mechanical strength, and degradation of scaffolds were investigated. Second, the biocompatibility and osteoinductivity were evaluated and compared by co-culture of scaffolds with bone marrow stromal stem cells (BMSCs). The results showed that the adhesion, proliferation, and osteogenic differentiation of BMSCs with nHA/PLGA (50/50) were better than those with nHA/PLGA (20/80). Finally, we implanted the scaffolds into femur bone defects in a rabbit model, then the capacity of guiding bone regeneration as well as the in vivo degradation were observed by micro-CT and histological examinations. After 4 weeks' implantation, there was no significant difference on the repair of bone defects. However, after 8 and 12 weeks' implantation, the nHA/PLGA (20/80) exhibited better bone formation than nHA/PLGA (50/50). These results suggested that a proper concentration of nHA in the nHA/PLGA composite should be taken into account when the composite scaffolds were prepared, which plays an important role in the biocompatibility, degradation rate and osteoconductivity.

  4. Polyphosphazene/Nano-Hydroxyapatite Composite Microsphere Scaffolds for Bone Tissue Engineering

    PubMed Central

    Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Brown, Justin L.; Krogman, Nicholas R.; Weikel, Arlin L.; Hindenlang, Mark D.; Nair, Lakshmi S.; Allcock, Harry R; Laurencin, Cato T.

    2009-01-01

    The non-toxic, neutral degradation products of amino acid ester polyphosphazenes make them ideal candidates for in vivo orthopaedic applications. The quest for new osteocompatible materials for load bearing tissue engineering applications has led us to investigate mechanically competent amino acid ester substituted polyphosphazenes. In this study, we have synthesized three biodegradable polyphosphazenes substituted with side groups namely leucine, valine and phenylalanine ethyl esters. Of these polymers, the phenylalanine ethyl ester substituted polyphosphazene showed the highest glass transition temperature (41.6 °C) and hence was chosen as a candidate material for forming composite microspheres with 100 nm sized hydroxyapatite (nHAp). The fabricated composite microspheres were sintered into a three-dimensional (3-D) porous scaffold by adopting a dynamic solvent sintering approach. The composite microsphere scaffolds showed compressive moduli of 46–81 MPa with mean pore diameters in the range of 86–145 µm. The three-dimensional polyphosphazene-nHAp composite microsphere scaffolds showed good osteoblast cell adhesion, proliferation and alkaline phosphatase expression, and are potential suitors for bone tissue engineering applications. PMID:18517248

  5. The Effect of Temozolomide/Poly(lactide-co-glycolide) (PLGA)/Nano-Hydroxyapatite Microspheres on Glioma U87 Cells Behavior

    PubMed Central

    Zhang, Dongyong; Tian, Ang; Xue, Xiangxin; Wang, Mei; Qiu, Bo; Wu, Anhua

    2012-01-01

    In this study, we investigated the effects of temozolomide (TMZ)/Poly (lactide-co-glycolide)(PLGA)/nano-hydroxyapatite microspheres on the behavior of U87 glioma cells. The microspheres were fabricated by the “Solid/Water/Oil” method, and they were characterized by using X-Ray diffraction, scanning electron microscopy and differential scanning calorimetry. The proliferation, apoptosis and invasion of glioma cells were evaluated by MTT, flow cytometry assay and Transwell assay. The presence of the key invasive gene, αVβ3 integrin, was detected by the RT-PCR and Western blot method. It was found that the temozolomide/PLGA/nano-hydroxyapatite microspheres have a significantly diminished initial burst of drug release, compared to the TMZ laden PLGA microspheres. Our results suggest they can significantly inhibit the proliferation and invasion of glioma cells, and induce their apoptosis. Additionally, αVβ3 integrin was also reduced by the microspheres. These data suggest that by inhibiting the biological behavior of glioma cells in vitro, the newly designed temozolomide/PLGA/nano-hydroxyapatite microspheres, as controlled drug release carriers, have promising potential in treating glioma. PMID:22312307

  6. Microsphere-Based Scaffolds Encapsulating Tricalcium Phosphate And Hydroxyapatite For Bone Regeneration

    PubMed Central

    Gupta, Vineet; Lyne, Dina V.; Barragan, Marilyn; Berkland, Cory J.; Detamore, Michael S.

    2016-01-01

    Bioceramic mixtures of tricalcium phosphate (TCP) and hydroxyapatite (HAp) are widely used for bone regeneration because of their excellent cytocompatibility, osteoconduction, and osteoinduction. Therefore, we hypothesized that incorporation of a mixture of TCP and HAp in microsphere-based scaffolds would enhance osteogenesis of rat bone marrow stromal cells (rBMSCs) compared to a positive control of scaffolds with encapsulated bone-morphogenic protein-2 (BMP-2). Poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds encapsulating TCP and HAp mixtures in two different ratios (7:3 and 1:1) were fabricated with the same net ceramic content (30 wt%) to evaluate how incorporation of these ceramic mixtures would affect the osteogenesis in rBMSCs. Encapsulation of TCP/HAp mixtures impacted microsphere morphologies and the compressive moduli of the scaffolds. Additionally, TCP/HAp mixtures enhanced the end-point secretion of extracellular matrix (ECM) components relevant to bone tissue compared to the “blank” (PLGA-only) microsphere-based scaffolds as evidenced by the biochemical, gene expression, histology, and immunohistochemical characterization. Moreover, the TCP/HAp mixture groups even surpassed the BMP-2 positive control group in some instances in terms of matrix synthesis and gene expression. Lastly, gene expression data suggested that the rBMSCs responded differently to different TCP/HAp ratios presented to them. Altogether, it can be concluded that TCP/HAp mixtures stimulated the differentiation of rBMSCs toward an osteoblastic phenotype, and therefore may be beneficial in gradient microsphere-based scaffolds for osteochondral regeneration. PMID:27272903

  7. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects.

    PubMed

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-02-02

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis.

  8. Levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffold for the treatment of chronic osteomyelitis with bone defects

    PubMed Central

    Wang, Qi; Chen, Cheng; Liu, Wen; He, Xiaoqiang; Zhou, Nian; Zhang, Dongli; Gu, Hongchen; Li, Jidong; Jiang, Jiaxing; Huang, Wei

    2017-01-01

    Chronic osteomyelitis is a prolonged persistent disease accompanied by bone destruction and sequestrum formation, it is very difficult to treat. Antibiotic loaded polymethyl methacrylate (PMMA) has been used in clinical. However, when PMMA was implanted in the body, the deficiencies is that it is non-biodegradable and a second operation is needed. Here, we synthesize a novel levofloxacin loaded mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds, and evaluated the therapeutic effect in treating chronic osteomyelitis with bone defects in rabbit model compared with bulk PMMA. X-ray, Micro CT, gross pathology as well as immunohistochemical staining were performed at predesignated time points (1, 3, 6 and 12 weeks). Our results demonstrated that the efficiency of mesoporous silica microspheres/nano-hydroxyapatite/polyurethane composite scaffolds loaded with 5 mg levofloxacin was much better at treating bone defects than the other groups. This novel synthetic scaffold may provide a solution for the treatment of chronic osteomyelitis. PMID:28150731

  9. Phase development and sintering behaviour of biphasic HA-TCP calcium phosphate materials prepared from hydroxyapatite and bioactive glass.

    PubMed

    Behnamghader, A; Bagheri, N; Raissi, B; Moztarzadeh, F

    2008-01-01

    The composites of hydroxyapatite (HA) with 2.5 and 5 wt% of a double oxide (50 mol% CaO and 50 mol% P(2)O(5)) glass were prepared using the conventional powder mixing and sintering method. The addition of the glass significantly enhanced the decomposition process of HA into alpha tricalcium phosphate (alpha-TCP) for bodies sintered at 1,300 and 1,350 degrees C and beta-TCP phases for the ones sintered at 1,200, 1,250 and 1,300 degrees C. Microstructural characteristics, phase development and thermal behaviour were studied by SEM, XRD and STA. The effects of TCP phase content and phase transformation from beta-TCP to alpha-TCP on the sintering are discussed. The characterizations revealed considerable content of TCP in the form of large semi-islands due to important reactions between the fine HA and the glass mixed powders.

  10. Physicochemical and mechanical properties of freeze cast hydroxyapatite-gelatin scaffolds with dexamethasone loaded PLGA microspheres for hard tissue engineering applications.

    PubMed

    Ghorbani, Farnaz; Nojehdehian, Hanieh; Zamanian, Ali

    2016-12-01

    Hydroxyapatite (HA)-gelatin scaffolds incorporated with dexamethasone-loaded polylactic-co-glycolic acid (PLGA) microspheres were synthesized by freeze casting technique. Scanning electron microscopy (SEM) micrographs demonstrated a unidirectional microstructure and a decrease in the pore size as a function of temperature gradient. Higher amounts of HA resulted in a decrease in the pore size. According to the results, at lower cooling rates, the formation of a lamellar structure decreased the mechanical strength, but at the same time, enhanced the swelling ratio, biodegradation rate and drug release level. On the other hand, higher weight ratios of HA increased the compressive strength, and reduced the swelling ratio, biodegradation rate and drug release level. The results obtained by furrier transform infrared spectroscopy (FTIR) and bioactivity analysis illustrated that the interactions of the materials support the apatite formation in the simulated body fluid (SBF) solution. Based on the obtained results, the synthesized composite scaffolds have the necessary mechanical and physicochemical features to support the regeneration of defects and to maintain their stability during the neo-tissue formation.

  11. Part II: crystalline fluorapatite-coated hydroxyapatite implant material: a dog study with histologic comparison of osteogenesis seen with FA-coated HA grafting material versus HA controls: potential bacteriostatic effect of fluoridated HA.

    PubMed

    Nordquist, William D; Okudera, Hajima; Kitamura, Yutaka; Kimoto, Kazunari; Okudera, Toshimitsu; Krutchkoff, David J

    2011-01-01

    Success of osteogenesis in bone graft procedures can be enhanced by inhibiting oral bacterial infections through the use of prophylactic bacteriostatic fluoride within the grafting environment. Ideally, the fluoride ion should be chemically sequestered and thus unavailable unless needed at times during the process of early infection. As fluoride within fluorapatite is tightly bound at neutral pH and becomes available only during acidic conditions, fluorapatite is an ideal store for the fluoride ion which becomes released for bacteriostasis only during an acidic environment found with incipient bacterial infection. The purpose of this investigation was to compare the histologic properties of new bone formed surrounding fluorapatite (FA)-coated microcrystalline hydroxyapatite (HA) grafting material with comparable bone formed following the use of control HA material (OsteoGen, Impladent, Ltd, Holliswood, NY). The results of histologic analysis within dog studies here showed no detectable difference in new bone following therapeutic grafting procedures using each of the above 2 mineral coatings.

  12. Hydroxyapatite (HA)/poly-L-lactic acid (PLLA) dual coating on magnesium alloy under deformation for biomedical applications.

    PubMed

    Diez, Mathilde; Kang, Min-Ho; Kim, Sae-Mi; Kim, Hyoun-Ee; Song, Juha

    2016-02-01

    The introduction of a protective coating layer to highly corrosive magnesium (Mg) has been proposed as one of the common approaches for improved corrosion resistance of Mg-based implants as load-bearing biomedical applications. However, only few studies have focused on the mechanical stability of the coated Mg under practical conditions where significant deformation of the load-bearing implants is induced during the surgical operation or under physiological environments. Therefore, in this study, we developed a dual coating system composed of an interlayer hydroxyapatite (HA) and a top layer poly-L-lactic acid (PLLA) to improve the coating stability under deformation of Mg alloy (WE43) substrate. The HA interlayer was directly formed on the Mg alloy surface, followed by dip-coating of PLLA. As the interlayer, HA improved the adhesion of PLLA by modulating nano- and microscale roughness, in addition to its inherently good bonding strength to Mg. The flexible and deformable top coating PLLA layer mitigated crack propagation in the HA layer under deformation. Thus, the dual coating layer provided good protection to the underlying WE43 from corrosion regardless of deformation. The enhanced corrosion behavior of dual-coated WE43 exhibited better mechanical and biological performance compared to the non-coated or single-coated WE43. Therefore, this dual coating layer on Mg is expected to accelerate Mg-based applications in biomedical devices.

  13. Silicon-hydroxyapatite bioactive coatings (Si-HA) from diatomaceous earth and silica. Study of adhesion and proliferation of osteoblast-like cells.

    PubMed

    López-Alvarez, M; Solla, E L; González, P; Serra, J; León, B; Marques, A P; Reis, R L

    2009-05-01

    The aim of this study consisted on investigating the influence of silicon substituted hydroxyapatite (Si-HA) coatings over the human osteoblast-like cell line (SaOS-2) behaviour. Diatomaceous earth and silica, together with commercial hydroxyapatite were respectively the silicon and HA sources used to produce the Si-HA coatings. HA coatings with 0 wt% of silicon were used as control of the experiment. Pulsed laser deposition (PLD) was the selected technique to deposit the coatings. The Si-HA thin films were characterized by Fourier Transformed Infrared Spectroscopy (FTIR) demonstrating the efficient transfer of Si to the HA structure. The in vitro cell culture was established to assess the cell attachment, proliferation and osteoblastic activity respectively by, Scanning Electron Microscopy (SEM), DNA and alkaline phosphatase (ALP) quantification. The SEM analysis demonstrated a similar adhesion behaviour of the cells on the tested materials and the maintenance of the typical osteoblastic morphology along the time of culture. The Si-HA coatings did not evidence any type of cytotoxic behaviour when compared with HA coatings. Moreover, both the proliferation rate and osteoblastic activity results showed a slightly better performance on the Si-HA coatings from diatoms than on the Si-HA from silica.

  14. Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty

    PubMed Central

    2011-01-01

    Background It is unclear whether there is a clinical benefit to adding hydroxyapatite (HA) coatings to total knee implants, especially with the tibial component, where failure of the implant more often occurs. A systematic review of the literature was undertaken to identify all prospective randomized trials for determining whether the overall clinical results (as a function of durability, function, and adverse events) favored HA-coated tibial components. Methods A comprehensive literature search was performed for the years 1990 to September 16, 2010. We restricted our search to randomized controlled trials involving participants receiving either an HA-coated tibia or other forms of tibial fixation. The primary outcome measures evaluated were durability, function, and acute adverse events. Results Data from 926 evaluable primary total knee implants in 14 studies were analyzed. Using an RSA definition for durability, HA-coated tibial components (porous or press-fit) without screw fixation were less likely to be unstable at 2 years than porous and cemented metal-backed tibial components (RR = 0.58, 95% CI: 0.34–0.98; p = 0.04, I2 = 39%, M-H random effects model). There was no significant difference in durability, as measured from revision and evaluated at 2 and 8–10 years, between groups. Also, functional status using different validated measures showed no significant difference at 2 and 5 years, no matter what measure was used. Lastly, there was no significant difference in adverse events. Limitations included small numbers of evaluable patients (≤ 50) in 7 of the 14 trials identified, and a lack of “hard” evidence of durability with need for replacement (i.e. frank failure, pain, or loss of functionality). Interpretation In patients > 65 years of age, an HA-coated tibial implant may provide better durability than other forms of tibial fixation. Larger trials should be undertaken comparing the long-term durability, function, and adverse events of HA

  15. Thermal Characteristic Of Waste-Derived Hydroxyapatite (HA) Reinforced Ultra High Molecular Weight Polyethylene (UHMWPE) Composites For Fused Deposition Modeling (FDM) Process

    NASA Astrophysics Data System (ADS)

    Ansari, Mohamad Helmi Bin Md; Ibrahim, Mohd Halim Irwan Bin

    2017-01-01

    The present study provides a hydrothermal synthesis to obtain Hydroxyapatite (HA) powder from waste eggshells. This waste-derived HA has been characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis. Waste-derived HA will be reinforced the Ultra-High Molecular Weight Polyethylene (UHMWPE) to develop a material composite for biomedical applications because of impressive mechanical properties owned by UHMWPE. Main challenger is UHMWPE has an ultra-high viscosity that renders continuous melt- state processes including one of the additive manufacturing processes which is Fused Deposition Modeling (FDM). To develop this material as feedstock in FDM process, it has been overcome by blending UHMWPE with waste-derived HA as filler. It exhibit the inclusion of 50wt% HA has reduced the degradation temperature in TGA and DSC thus enhances the processability in FDM process.

  16. Microspheres

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  17. Evaluation of zinc-doped mesoporous hydroxyapatite microspheres for the construction of a novel biomimetic scaffold optimized for bone augmentation

    PubMed Central

    Yu, Weilin; Sun, Tuan-Wei; Qi, Chao; Ding, Zhenyu; Zhao, Huakun; Zhao, Shichang; Shi, Zhongmin; Zhu, Ying-Jie; Chen, Daoyun; He, Yaohua

    2017-01-01

    Biomaterials with high osteogenic activity are desirable for sufficient healing of bone defects resulting from trauma, tumor, infection, and congenital abnormalities. Synthetic materials mimicking the structure and composition of human trabecular bone are of considerable potential in bone augmentation. In the present study, a zinc (Zn)-doped mesoporous hydroxyapatite microspheres (Zn-MHMs)/collagen scaffold (Zn-MHMs/Coll) was developed through a lyophilization fabrication process and designed to mimic the trabecular bone. The Zn-MHMs were synthesized through a microwave-hydrothermal method by using creatine phosphate as an organic phosphorus source. Zn-MHMs that consist of hydroxyapatite nanosheets showed relatively uniform spherical morphology, mesoporous hollow structure, high specific surface area, and homogeneous Zn distribution. They were additionally investigated as a drug nanocarrier, which was efficient in drug delivery and presented a pH-responsive drug release behavior. Furthermore, they were incorporated into the collagen matrix to construct a biomimetic scaffold optimized for bone tissue regeneration. The Zn-MHMs/Coll scaffolds showed an interconnected pore structure in the range of 100–300 μm and a sustained release of Zn ions. More importantly, the Zn-MHMs/Coll scaffolds could enhance the osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells. Finally, the bone defect repair results of critical-sized femoral condyle defect rat model demonstrated that the Zn-MHMs/Coll scaffolds could enhance bone regeneration compared with the Coll or MHMs/Coll scaffolds. The results suggest that the biomimetic Zn-MHMs/Coll scaffolds may be of enormous potential in bone repair and regeneration. PMID:28392688

  18. Response of Human Osteoblast to n-HA/PEEK—Quantitative Proteomic Study of Bio-effects of Nano-Hydroxyapatite Composite

    PubMed Central

    Zhao, Minzhi; Li, Haiyun; Liu, Xiaochen; Wei, Jie; Ji, Jianguo; Yang, Shu; Hu, Zhiyuan; Wei, Shicheng

    2016-01-01

    Nano-sized hydroxyapatite (n-HA) is considered as a bio-active material, which is often mixed into bone implant material, polyetheretherketone (PEEK). To reveal the global protein expression modulations of osteoblast in response to direct contact with the PEEK composite containing high level (40%) nano-sized hydroxyapatite (n-HA/PEEK) and explain its comprehensive bio-effects, quantitative proteomic analysis was conducted on human osteoblast-like cells MG-63 cultured on n-HA/PEEK in comparison with pure PEEK. Results from quantitative proteomic analysis showed that the most enriched categories in the up-regulated proteins were related to calcium ion processes and associated functions while the most enriched categories in the down-regulated proteins were related to RNA process. This enhanced our understanding to the molecular mechanism of the promotion of the cell adhesion and differentiation with the inhibition of the cell proliferation on n-HA/PEEK composite. It also exhibited that although the calcium ion level of incubate environment hadn’t increased, merely the calcium fixed on the surface of material had influence to intracellular calcium related processes, which was also reflect by the higher intracellular Ca2+ concentration of n-HA/PEEK. This study could lead to more comprehensive cognition to the versatile biocompatibility of composite materials. It further proves that proteomics is useful in new bio-effect discovery. PMID:26956660

  19. Response of Human Osteoblast to n-HA/PEEK--Quantitative Proteomic Study of Bio-effects of Nano-Hydroxyapatite Composite.

    PubMed

    Zhao, Minzhi; Li, Haiyun; Liu, Xiaochen; Wei, Jie; Ji, Jianguo; Yang, Shu; Hu, Zhiyuan; Wei, Shicheng

    2016-03-09

    Nano-sized hydroxyapatite (n-HA) is considered as a bio-active material, which is often mixed into bone implant material, polyetheretherketone (PEEK). To reveal the global protein expression modulations of osteoblast in response to direct contact with the PEEK composite containing high level (40%) nano-sized hydroxyapatite (n-HA/PEEK) and explain its comprehensive bio-effects, quantitative proteomic analysis was conducted on human osteoblast-like cells MG-63 cultured on n-HA/PEEK in comparison with pure PEEK. Results from quantitative proteomic analysis showed that the most enriched categories in the up-regulated proteins were related to calcium ion processes and associated functions while the most enriched categories in the down-regulated proteins were related to RNA process. This enhanced our understanding to the molecular mechanism of the promotion of the cell adhesion and differentiation with the inhibition of the cell proliferation on n-HA/PEEK composite. It also exhibited that although the calcium ion level of incubate environment hadn't increased, merely the calcium fixed on the surface of material had influence to intracellular calcium related processes, which was also reflect by the higher intracellular Ca(2+) concentration of n-HA/PEEK. This study could lead to more comprehensive cognition to the versatile biocompatibility of composite materials. It further proves that proteomics is useful in new bio-effect discovery.

  20. Enhanced osteogenesis and angiogenesis by mesoporous hydroxyapatite microspheres-derived simvastatin sustained release system for superior bone regeneration

    PubMed Central

    Yu, Wei-Lin; Sun, Tuan-Wei; Qi, Chao; Zhao, Hua-Kun; Ding, Zhen-Yu; Zhang, Zhi-Wang; Sun, Ben-Ben; Shen, Ji; Chen, Feng; Zhu, Ying-Jie; Chen, Dao-Yun; He, Yao-Hua

    2017-01-01

    Biomaterials with both excellent osteogenic and angiogenic activities are desirable to repair massive bone defects. In this study, simvastatin with both osteogenic and angiogenic activities was incorporated into the mesoporous hydroxyapatite microspheres (MHMs) synthesized through a microwave-assisted hydrothermal method using fructose 1,6-bisphosphate trisodium salt (FBP) as an organic phosphorous source. The effects of the simvastatin-loaded MHMs (S-MHMs) on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and angiogenesis in EA.hy926 cells were investigated. The results showed that the S-MHMs not only enhanced the expression of osteogenic markers in rBMSCs but also promoted the migration and tube formation of EA.hy926 cells. Furthermore, the S-MHMs were incorporated into collagen matrix to construct a novel S-MHMs/collagen composite scaffold. With the aid of MHMs, the water-insoluble simvastatin was homogenously incorporated into the hydrophilic collagen matrix and presented a sustained release profile. In vivo experiments showed that the S-MHMs/collagen scaffolds enhanced the bone regeneration and neovascularization simultaneously. These results demonstrated that the water-insoluble simvastatin could be incorporated into the MHMs and maintained its biological activities, more importantly, the S-MHMs/collagen scaffolds fabricated in this study are of immense potential in bone defect repair by enhancing osteogenesis and angiogenesis simultaneously. PMID:28287178

  1. In vitro degradation and cytocompatibility of dicalcium phosphate dihydrate cements prepared using the monocalcium phosphate monohydrate/hydroxyapatite system reveals rapid conversion to HA as a key mechanism.

    PubMed

    Alge, Daniel L; Goebel, W Scott; Chu, Tien-Min Gabriel

    2012-04-01

    We previously showed that dicalcium phosphate dihydrate (DCPD) cements can be prepared using monocalcium phosphate monohydrate (MCPM) and hydroxyapatite (HA). In this study, we have characterized the degradation properties and biocompatibility of these novel cements. To study the degradation properties, cements were prepared using MCPM:HA molar ratios of 4:1, 2:1, 2:3, and 2:5. Degradation was evaluated in vitro by static soaking in PBS, and changes in pH, mass, compressive strength, and composition were monitored. Conversion of DCPD to HA was noted in the 4:1 group, which initially consisted of pure DCPD. However, the 2:1 group, which initially consisted of DCPD and an intermediate amount of unreacted HA, underwent rapid conversion to HA associated with significantly greater pH drop and mass loss as well as a complete loss of mechanical integrity. On the basis of these results, we directly compared the cytocompatibility of 2:1 MCPM:HA cements to DCPD cements prepared with an equivalent percent molar excess of β-tricalcium phosphate (β-TCP) using an in vitro cell viability assay. Viability of cells co-cultured with 2:1 MCPM:HA cements was significantly reduced after just 48 h, while viability of cells cultured with the β-TCP-based cements was no different from control cells. In conclusion, this study demonstrates that conversion to HA plays an important role in the degradation of DCPD cements prepared with the MCPM/HA system, affecting both physical properties and cytocompatibility. These results could have important clinical implications for MCPM/HA cements.

  2. Development of Microspheres Covered with Hydroxyapatite Nanocrystals as Cell Scaffold for Angiogenesis

    NASA Astrophysics Data System (ADS)

    Iwamoto, Takashi; Terada, Takahiro; Kogai, Yasumichi; Okada, Masahiro; Fujii, Syuji; Furuzono, Tsutomu

    2012-06-01

    We prepared poly(L-lactide-co-glycolide) cell scaffolds coated with hydroxyapatite (HAp) nanocrystals with 50-100 nm in diameter via the Pickering emulsion method. Our cell scaffolds were composed of biodegradable polymers and HAp nanocrystals as a core and shell, respectively. The scaffolds were spherical but displayed uneven shapes when altering a shear speed of homogenization during syntheses. The surface coverage of HAp nanocrystals was examined because the HAp-coating ratio for the scaffolds was an important factor as cell scaffolds in order to enhance cell adhesion. On the basis of scanning electron microscopy observations and thermogravimetric analyses, it was found that the cell scaffolds showed distorted morphologies, and the HAp-coating ratio decreased with increasing the shear speed in the synthesis because shear stress influenced shapes of the scaffolds.

  3. In vitro and in vivo evaluations of nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) as a novel bioactive bone screw.

    PubMed

    Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

    2013-01-01

    In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications.

  4. Comparison between PCL/hydroxyapatite (HA) and PCL/halloysite nanotube (HNT) composite scaffolds prepared by co-extrusion and gas foaming.

    PubMed

    Jing, Xin; Mi, Hao-Yang; Turng, Lih-Sheng

    2017-03-01

    In this work, three-dimensional poly(caprolactone) (PCL) tissue engineering scaffolds were prepared by co-extrusion and gas foaming. Biocompatible hydroxyapatite (HA) and halloysite nanotubes (HNT) were added to the polymer matrix to enhance the mechanical properties and bioactivity of the composite scaffolds. The effects of HA and HNT on the rheological behavior, microstructure, and mechanical properties of the composite scaffolds were systematically compared. It was found that the HNT improved viscosity more significantly than HA, and reduced the pore size of scaffolds, while the mechanical performance of PCL/HNT scaffolds was higher than PCL/HA scaffolds with the same filler content. Human mesenchymal stem cells (hMSCs) were used as the cell model to compare the biological properties of two composite scaffolds. The results demonstrated that cells could survive on all scaffolds, and showed a more flourishing living state on the composite scaffolds. The cell differentiation for 5% HA and 1% HNT scaffolds were significantly higher than other scaffolds, while the differentiation of 5% HNT scaffolds was lower than that of 1% HNT scaffolds mainly because of the reduced pore size and pore interconnectivity. Therefore, this study suggested that, with proper filler content and control of microstructure through processing, HNT could be a suitable substitute for HA for bone tissue engineering to reduce the cost and improve mechanical performance.

  5. In Vitro and In Vivo Evaluations of Nano-Hydroxyapatite/Polyamide 66/Glass Fibre (n-HA/PA66/GF) as a Novel Bioactive Bone Screw

    PubMed Central

    Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

    2013-01-01

    In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications. PMID:23861888

  6. Injectable alginate/hydroxyapatite gel scaffold combined with gelatin microspheres for drug delivery and bone tissue engineering.

    PubMed

    Yan, Jingxuan; Miao, Yuting; Tan, Huaping; Zhou, Tianle; Ling, Zhonghua; Chen, Yong; Xing, Xiaodong; Hu, Xiaohong

    2016-06-01

    Injectable and biodegradable alginate-based composite gel scaffolds doubly integrated with hydroxyapatite (HAp) and gelatin microspheres (GMs) were cross-linked via in situ release of calcium cations. As triggers of calcium cations, CaCO3 and glucono-D-lactone (GDL) were fixed as a mass ratio of 1:1 to control pH value ranging from 6.8 to 7.2 during gelation. Synchronously, tetracycline hydrochloride (TH) was encapsulated into GMs to enhance bioactivity of composite gel scaffolds. The effects of HAp and GMs on characteristics of gel scaffolds, including pH value, gelation time, mechanical properties, swelling ratio, degradation behavior and drug release, were investigated. The results showed that HAp and GMs successfully improved mechanical properties of gel scaffolds at strain from 0.1 to 0.5, which stabilized the gel network and decreased weight loss, as well as swelling ratio and gelation time. TH could be released from this composite gel scaffold into the local microenvironment in a controlled fashion by the organic/inorganic hybrid of hydrogel network. Our results demonstrate that the HAp and GMs doubly integrated alginate-based gel scaffolds, especially the one with 6% (w/v) HAp and 5% (w/v) GMs, have suitable physical performance and bioactive properties, thus provide a potential opportunity to be used for bone tissue engineering. The potential application of this gel scaffold in bone tissue engineering was confirmed by encapsulation behavior of osteoblasts. In combination with TH, the gel scaffold exhibited beneficial effects on osteoblast activity, which suggested a promising future for local treatment of pathologies involving bone loss.

  7. Analyzing the behavior of a porous nano-hydroxyapatite/polyamide 66 (n-HA/PA66) composite for healing of bone defects.

    PubMed

    Xiong, Yan; Ren, Cheng; Zhang, Bin; Yang, Hongsheng; Lang, Yun; Min, Li; Zhang, Wenli; Pei, Fuxing; Yan, Yonggang; Li, Hong; Mo, Anchun; Tu, Chongqi; Duan, Hong

    2014-01-01

    The aim of this study was to analyze the behavior of the porous nano-hydroxyapatite/polyamide 66 (n-HA/PA66) composite grafted for bone defect repair through a series of biological safety experiments, animal experiments, and a more than 5-year long clinical follow-up. The biological safety experiments, carried out in accordance with the Chinese Guo Biao and Tolerancing (GB/T)16886 and GB/T16175, revealed that porous n-HA/PA66 composite had no cytotoxicity, no sensitization effect, no pyrogenic reaction, and that its hemolysis rate was 0.59% (less than 5%). Rabbit models of tibia defects with grafted porous n-HA/PA66 composite were established. After 2 weeks, the experiment showed that osteogenesis was detected in the porous n-HA/PA66 composite; the density of new bone formation was similar to the surrounding host bone at 12 weeks. After 26 weeks, the artificial bone rebuilt to lamellar bone completely. In the clinical study, a retrospective review was carried out for 21 patients who underwent serial radiographic assessment after treatment with porous n-HA/PA66 composite grafts following bone tumor resection. All wounds healed to grade A. No postoperative infections, delayed deep infection, nonspecific inflammation, rejection, or fractures were encountered. At a mean follow-up of 5.3 years, the mean Musculoskeletal Tumor Society's (MSTS) 93 score was 29.3 points (range: 28-30 points) and mean radiopaque density ratio was 0.77±0.10. The radiologic analysis showed that porous n-HA/PA66 composite had been completely incorporated with the host bone about 1.5 years later. In conclusion, this study indicated that the porous n-HA/PA66 composite had biological safety, and good biocompatibility, osteoinduction, and osseointegration. Thus, the porous n-HA/PA66 composite is an ideal artificial bone substitute and worthy of promotion in the field.

  8. Synergistic Effect of Mesoporous Silica and Hydroxyapatite in Loaded Poly(DL-lactic-co-glycolic acid) Microspheres on the Regeneration of Bone Defects

    PubMed Central

    Lin, Kai-Feng; Fan, Jun-Jun; Hu, Gang; Dong, Xin; Zhao, Yi-Nan; Song, Yue; Guo, Zhong-Shang

    2016-01-01

    A microsphere composite made of poly(DL-lactic-co-glycolic acid) (PLGA), mesoporous silica nanoparticle (MSN), and nanohydroxyapatite (nHA) (PLGA-MSN/nHA) was prepared and evaluated as bone tissue engineering materials. The objective of this study was to investigate the synergistic effect of MSN/nHA on biocompatibility as well as its potential ability for bone formation. First, we found that this PLGA-MSN/nHA composite performed good characteristics on microstructure, mechanical strength, and wettability. By cell culture experiments, the adhesion and proliferation rate of the cells seeded on PLGA-MSN/nHA composite was higher than those of the controls and high levels of osteogenetic factors such as ALP and Runx-2 were detected by reverse transcriptase polymerase chain reaction. Finally, this PLGA-MSN/nHA composite was implanted into the femur bone defect in a rabbit model, and its ability to induce bone regeneration was observed by histological examinations. Twelve weeks after implantation, the bone defects had significantly more formation of mature bone and less residual materials than in the controls. These results demonstrate that this PLGA-MSN/nHA composite, introducing both MSN and nHA into PLGA microspheres, can improve the biocompatibility and osteoinductivity of composite in vitro and in vivo and had potential application in bone regeneration. PMID:27652269

  9. Synergistic Effect of Mesoporous Silica and Hydroxyapatite in Loaded Poly(DL-lactic-co-glycolic acid) Microspheres on the Regeneration of Bone Defects.

    PubMed

    He, Shu; Lin, Kai-Feng; Fan, Jun-Jun; Hu, Gang; Dong, Xin; Zhao, Yi-Nan; Song, Yue; Guo, Zhong-Shang; Bi, Long; Liu, Jian

    2016-01-01

    A microsphere composite made of poly(DL-lactic-co-glycolic acid) (PLGA), mesoporous silica nanoparticle (MSN), and nanohydroxyapatite (nHA) (PLGA-MSN/nHA) was prepared and evaluated as bone tissue engineering materials. The objective of this study was to investigate the synergistic effect of MSN/nHA on biocompatibility as well as its potential ability for bone formation. First, we found that this PLGA-MSN/nHA composite performed good characteristics on microstructure, mechanical strength, and wettability. By cell culture experiments, the adhesion and proliferation rate of the cells seeded on PLGA-MSN/nHA composite was higher than those of the controls and high levels of osteogenetic factors such as ALP and Runx-2 were detected by reverse transcriptase polymerase chain reaction. Finally, this PLGA-MSN/nHA composite was implanted into the femur bone defect in a rabbit model, and its ability to induce bone regeneration was observed by histological examinations. Twelve weeks after implantation, the bone defects had significantly more formation of mature bone and less residual materials than in the controls. These results demonstrate that this PLGA-MSN/nHA composite, introducing both MSN and nHA into PLGA microspheres, can improve the biocompatibility and osteoinductivity of composite in vitro and in vivo and had potential application in bone regeneration.

  10. Degradation pattern of porous CaCO3 and hydroxyapatite microspheres in vitro and in vivo for potential application in bone tissue engineering.

    PubMed

    Zhong, Qiwei; Li, Wenhua; Su, Xiuping; Li, Geng; Zhou, Ying; Kundu, Subhas C; Yao, Juming; Cai, Yurong

    2016-07-01

    Despite superior clinical handling, excellent biocompatibility, biodegradation property of calcium phosphate needs to be improved to coincide with the rate of new bone formation. In this study, spherical CaCO3 are fabricated in the presence of the silk sericin and then transformed into porous hydroxyapatite (HAP) microspheres via hydrothermal method. The degradation behavior of obtained CaCO3, HAP and their mixture is first investigated in vitro. The result demonstrates that the weight loss of HAP microspheres are almost 24.3% after immersing in pH 7.40 Tris-HCl buffer solution for 12 weeks, which is far slower than that of spherical CaCO3 (97.5%). The degradation speed of the mixtures depends on the proportion of CaCO3 and HAP. The mixture with higher content of CaCO3 possesses a quicker degradation speed. The obtained CaCO3 and HAP microspheres are injected into subcutaneous tissue of ICR mice with the assistance of sodium alginate. The result in vivo also shows an obvious difference of degradation speed between the obtained CaCO3 and HAP microspheres, implying it is feasible to modulate the degradation property of the mixture through changing the proportion of CaCO3 and HAP The good cytocompatibility of the two kinds of microspheres is proved and a mild inflammation response is observed only at early stage of implantation. The job offers a simple method to modify the degradation properties of biomaterial for potential use in bone tissue engineering.

  11. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of D-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications.

  12. Bioactive apatite incorporated alginate microspheres with sustained drug-delivery for bone regeneration application.

    PubMed

    Li, Haibin; Jiang, Fei; Ye, Song; Wu, Yingying; Zhu, Kaiping; Wang, Deping

    2016-05-01

    The strontium-substituted hydroxyapatite microspheres (SrHA) incorporated alginate composite microspheres (SrHA/Alginate) were prepared via adding SrHA/alginate suspension dropwise into calcium chloride solution, in which the gel beads were formed by means of crosslinking reaction. The structure, morphology and in vitro bioactivity of the composite microspheres were studied by using XRD, SEM and EDS methods. The biological behaviors were characterized and analyzed through inductively coupled plasma optical emission spectroscopy (ICP-OES), CCK-8, confocal laser microscope and ALP activity evaluations. The experimental results indicated that the synthetic SrHA/Alginate showed similar morphology to the well-known alginate microspheres (Alginate) and both of them possessed a great in vitro bioactivity. Compared with the control Alginate, the SrHA/Alginate enhanced MC3T3-E1 cell proliferation and ALP activity by releasing osteoinductive and osteogenic Sr ions. Furthermore, vancomycin was used as a model drug to investigate the drug release behaviors of the SrHA/Alginate, Alginate and SrHA. The results suggested that the SrHA/Alginate had a highest drug-loading efficiency and best controlled drug release properties. Additionally, the SrHA/Alginate was demonstrated to be pH-sensitive as well. The increase of the pH value in phosphate buffer solution (PBS) accelerated the vancomycin release. Accordingly, the multifunctional SrHA/Alginate can be applied in the field of bioactive drug carriers and bone filling materials.

  13. Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly L-lactide (PLLA). Part II: practical properties of miniscrews and miniplates.

    PubMed

    Shikinami, Y; Okuno, M

    2001-12-01

    Miniscrews and miniplates made of forged composites composed of raw hydroxyapatite (u-HA) particles (particle size 0.2-20 microm, averaging 3.0 microm, Ca/p = 1.69 and containing CO3(2-)) and a poly L-lactide (PLLA, Mv: about 180 kDa, containing residual 0.05 wt% lactide) with osteological bioactivity such as direct bonding to bone and osteoconductivity, total resorbability and radiopacity were examined for various mechanical properties in order to evaluate their usefulness for cranio-, oral and maxillo-facial as well as plastic and reconstructive surgeries with PLLA-only or titanium devices. The composites containing u-HA particles at 30wt% for miniscrews and 40wt% for miniplates were selected based on total mechanical strengths and bioactivity, respectively. It was found that the composite devices generally had slightly different mechanical properties than forged PLLA-only devices of which strengths are ranked the highest among the reinforced PLLA-only ones that having been used in many clinical cases to date, in spite of their approximate 2 or 3 times lower absolute strengths than those of titanium ones. However, a remarkable distinction that makes the composite miniplates stand above the titanium ones was confirmed on their fatigue resistance to alternate bendings such that they retained 70% of their initial strength even after 60 times without revealing any damage, whereas the metallic devices fully broke off at only 8 times. This behavior was similar to that of forged PLLA-only devices but is unique as composites made of organic polymers divided by inorganic particles. In addition, profile plates such as L-, T-, X, T, C-, Mesh-, Box-, and Barhole types which were processed by forging twice exhibited nearly directional isotropy in strength and could be deformed in situ at ordinary temperatures to adjust their shapes along the surface undulations of the skull, mandible, maxilla, zygomatic bone and the like without thermoforming and did not return to their

  14. Porous nano-hydroxyapatite/collagen scaffold containing drug-loaded ADM-PLGA microspheres for bone cancer treatment.

    PubMed

    Rong, Zi-Jie; Yang, Lian-Jun; Cai, Bao-Ta; Zhu, Li-Xin; Cao, Yan-Lin; Wu, Guo-Feng; Zhang, Zan-Jie

    2016-05-01

    To develop adriamycin (ADM)-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles in a porous nano-hydroxyapatite/collagen scaffold (ADM-PLGA-NHAC). To provide novel strategies for future treatment of osteosarcoma, the properties of the scaffold, including its in vitro extended-release properties, the inhibition effects of ADM-PLGA-NHAC on the osteosarcoma MG63 cells, and its bone repair capacity, were investigated in vivo and in vitro. The PLGA copolymer was utilized as a drug carrier to deliver ADM-PLGA nanoparticles (ADM-PLGA-NP). Porous nano-hydroxyapatite and collagen were used to materials to produce the porous nano-hydroxyapatite/collagen scaffold (NHAC), into which the ADM-PLGA-NP was loaded. The performance of the drug-carrying scaffold was assessed using multiple techniques, including scanning electron microscopy and in vitro extended release. The antineoplastic activities of scaffold extracts on the human osteosarcoma MG63 cell line were evaluated in vitro using the cell counting kit-8 (CCK8) method and live-dead cell staining. The bone repair ability of the scaffold was assessed based on the establishment of a femoral condyle defect model in rabbits. ADM-PLGA-NHAC and NHAC were implanted into the rat muscle bag for immune response experiments. A tumor-bearing nude mice model was created, and the TUNEL and HE staining results were observed under optical microscopy to evaluate the antineoplastic activity and toxic side effects of the scaffold. The composite scaffold demonstrated extraordinary extended-release properties, and its extracts also exhibited significant inhibition of the growth of osteosarcoma MG63 cells. In the bone repair experiment, no significant difference was observed between ADM-PLGA-NHAC and NHAC by itself. In the immune response experiments, ADM-PLGA-NHAC exhibited remarkable biocompatibility. The in vivo antitumor experiment revealed that the implantation of ADM-PLGA-NHAC in the tumor resulted in a improved antineoplastic

  15. Treatment of Staphylococcus aureus-induced chronic osteomyelitis with bone-like hydroxyapatite/poly amino acid loaded with rifapentine microspheres

    PubMed Central

    Yan, Ling; Jiang, Dian-Ming; Cao, Zhi-Dong; Wu, Jun; Wang, Xin; Wang, Zheng-Long; Li, Ya-Jun; Yi, Yong-Fen

    2015-01-01

    Purpose The purpose of this study was to investigate the curative effect of bone-like hydroxyapatite/poly amino acid (BHA/PAA) as a carrier for poly(lactic-co-glycolic acid)-coated rifapentine microsphere (RPM) in the treatment of rabbit chronic osteomyelitis induced by Staphylococcus aureus. Methods RPM was prepared through an oil-in-water emulsion solvent evaporation method, and RPM was combined with BHA/PAA to obtain drug-loaded, slow-releasing materials. Twenty-six New Zealand white rabbits were induced to establish the animal model of chronic osteomyelitis. After debridement, the animals were randomly divided into three groups (n=8): the experimental group (with RPM-loaded BHA/PAA), the control group (with BHA/PAA), and the blank group. The RPM-loaded BHA/PAA was evaluated for antibacterial activity, dynamics of drug release, and osteogenic ability through in vitro and in vivo experiments. Results In vitro, RPM-loaded BHA/PAA released the antibiotics slowly, inhibiting the bacterial growth of S. aureus for up to 5 weeks. In vivo, at week 4, the bacterial colony count was significantly lower in the experimental group than in the control and blank groups (P<0.01). At week 12, the chronic osteomyelitis was cured and the bone defect was repaired in the experimental group, whereas the infection and bone defect persisted in the control and blank groups. Conclusion In vitro and in vivo experiments demonstrated that RPM-loaded BHA/PAA effectively cured S. aureus-induced chronic osteomyelitis. Therefore, BHA/PAA has potential value as a slow-releasing material in clinical setting. Further investigation is needed to determine the optimal dosage for loading rifapentine. PMID:26213463

  16. Optical and biological properties of transparent nanocrystalline hydroxyapatite obtained through spark plasma sintering.

    PubMed

    Li, Zhong; Thompson, Brianna C; Dong, Zhili; Khor, Khiam Aik

    2016-12-01

    Transparent bioceramics have attracted a large amount of research interest as they facilitate direct observation of biointerfacial reactions. Thus far, attempts to achieve transparent hydroxyapatite have been focused on augmenting the sintering pressure and/or extending the sintering duration. This study aims at fabricating transparent HA using a direct and fast spark plasma sintering process with appropriate starting powder and moderate sintering pressure. Three types of raw powder, namely micro-spheres, nano-rods and nano-spheres, were sintered to investigate the optical and biological properties of the compacted pellets. It was found that in terms of transparency, the micro-sphere pellet sintered at 1000°C stood out with an in-line transmittance as high as 84% achieved at 1300nm for a 2mm thick sample. In addition, pellets fabricated from micro-spheres demonstrated the highest cell viability in in vitro biological tests with L929 cells. Living cells cultured on a transparent micro-sphere pellet could be directly and clearly observed by light microscopy. It is thus concluded that the micro-sphere powder is the most desirable raw material to manufacture transparent hydroxyapatite because it could enable dense pellets with notably high transparency and outstanding in vitro biocompatibility to be readily obtained.

  17. Effect of bone-like hydroxyapatite/poly amino acid loaded with rifapentine microspheres on bone and joint tuberculosis in vitro.

    PubMed

    Liu, Yuwu; Jiang, Dianming

    2017-04-01

    Rifapentine-loaded poly(lactic-co-glycolic acid) microspheres (RPMs)-loaded bone-like hydroxyapatite/poly amino acid (BHA/PAA) is effective in curing Staphylococcus aureus-induced chronic osteomyelitis. This study continues to investigate the effect of RPM-loaded BHA/PAA on the bacterial growth of Mycobacterium tuberculosis (MTB), cell proliferation and differentiation in MTB H37Rv-infected MG63 cells. Furthermore, whether Wnt/β-catenin signaling pathway was activated by RPM-loaded BHA/PAA was explored. We found the bactec growth index of H37Rv was significantly inhibited by RPM-loaded BHA/PAA. The MTT assay showed that RPM-loaded BHA/PAA could promote the cell proliferation of H37Rv-infected MG63 cells, as determined by MTT assay. The alkaline phosphatase (ALP) activity and the expression of runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) was examined by commercial kit and Western blot analysis to determine the effect of RPM-loaded BHA/PAA on MTB H37Rv-infected MG63 cell differentiation. It was revealed that RPM-loaded BHA/PAA could promote cell differentiation of H37Rv-infected MG63 cells. Furthermore, we found the expression of Wnt1, LDL receptor related protein 6 (Lrp6) and β-catenin was significantly increased in H37Rv-infected MG63 cells following treatment with RPM-loaded BHA/PAA, as determined by Western blot analysis. In conclusion, this study demonstrated that RPM-loaded BHA/PAA has an effective activity against MTB. RPM-loaded BHA/PAA promoted cell proliferation and cell differentiation of H37Rv-infected MG63 cells. Wnt/β-catenin signaling could be activated by RPM-loaded BHA/PAA in MG63 cells infected with H37Rv. This study demonstrated the potential value of RPM-loaded BHA/PAA in treating bone and joint TB, and suggested Wnt/β-catenin signaling may be an important pathway underlying its function.

  18. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  19. Long-term conversion of 45S5 bioactive glass-ceramic microspheres in aqueous phosphate solution.

    PubMed

    Fu, Hailuo; Rahaman, Mohamed N; Day, Delbert E; Huang, Wenhai

    2012-05-01

    The conversion of 45S5 glass and glass-ceramics to a hydroxyapatite (HA)-like material in vitro has been studied extensively, but only for short reaction times (typically <3 months). In this paper, we report for the first time on the long-term conversion of 45S5 glass-ceramic microspheres (designated 45S5c) in an aqueous phosphate solution. Microspheres of 45S5c (75-150 μm) were immersed for 10 years at room temperature (~25 °C) in K(2)HPO(4) solution with a concentration of 0.01 M or 1.0 M, and with a starting pH of 7.0 or 9.5. The reacted 45S5c microspheres and solutions were analyzed using structural and analytical techniques. Only 25-45 vol% of the 45S5c microspheres were converted to an HA-like material after the 10 year reaction. In solutions with a starting pH of 9.5, an increase in the K(2)HPO(4) concentration from 0.01 to 1.0 M resulted in a doubling of the volume of the microspheres converted to an HA-like material but had little effect on the composition of the HA-like product. In comparison, reaction of the 45S5c microspheres in the solution with a starting pH of 7.0 resulted in an HA-like product in the 0.01 M K(2)HPO(4) solution but a calcium pyrophosphate product, Ca(10)K(4)(P(2)O(7))(6).9H(2)O, in the 1.0 M solution. The consequences of these results for the long-term use of 45S5 glass-ceramics in biomedical applications are discussed.

  20. Cytocompatibility and biocompatibility of nanostructured carbonated hydroxyapatite spheres for bone repair

    PubMed Central

    CALASANS-MAIA, Mônica Diuana; de MELO, Bruno Raposo; ALVES, Adriana Terezinha Neves Novellino; RESENDE, Rodrigo Figueiredo de Brito; LOURO, Rafael Seabra; SARTORETTO, Suelen Cristina; GRANJEIRO, José Mauro; ALVES, Gutemberg Gomes

    2015-01-01

    ABSTRACT Objective The aim of this study was to investigate the in vitro and in vivo biological responses to nanostructured carbonated hydroxyapatite/calcium alginate (CHA) microspheres used for alveolar bone repair, compared to sintered hydroxyapatite (HA). Material and Methods The maxillary central incisors of 45 Wistar rats were extracted, and the dental sockets were filled with HA, CHA, and blood clot (control group) (n=5/period/group). After 7, 21 and 42 days, the samples of bone with the biomaterials were obtained for histological and histomorphometric analysis, and the plasma levels of RANKL and OPG were determined via immunoassay. Statistical analysis was performed by Two-Way ANOVA with post-hoc Tukey test at 95% level of significance. Results The CHA and HA microspheres were cytocompatible with both human and murine cells on an in vitro assay. Histological analysis showed the time-dependent increase of newly formed bone in control group characterized by an intense osteoblast activity. In HA and CHA groups, the presence of a slight granulation reaction around the spheres was observed after seven days, which was reduced by the 42nd day. A considerable amount of newly formed bone was observed surrounding the CHA spheres and the biomaterials particles at 42-day time point compared with HA. Histomorphometric analysis showed a significant increase of newly formed bone in CHA group compared with HA after 21 and 42 days from surgery, moreover, CHA showed almost 2-fold greater biosorption than HA at 42 days (two-way ANOVA, p<0.05) indicating greater biosorption. An increase in the RANKL/OPG ratio was observed in the CHA group on the 7th day. Conclusion CHA spheres were osteoconductive and presented earlier biosorption, inducing early increases in the levels of proteins involved in resorption. PMID:26814461

  1. Nanoscale adhesion forces between enamel pellicle proteins and hydroxyapatite.

    PubMed

    Vukosavljevic, D; Hutter, J L; Helmerhorst, E J; Xiao, Y; Custodio, W; Zaidan, F C; Oppenheim, F G; Siqueira, W L

    2014-05-01

    The acquired enamel pellicle (AEP) is important for minimizing the abrasion caused by parafunctional conditions as they occur, for instance, during bruxism. It is a remarkable feature of the AEP that a protein/peptide film can provide enough protection in normofunction to prevent teeth from abrasion and wear. Despite its obvious critical role in the protection of tooth surfaces, the essential adhesion features of AEP proteins on the enamel surface are poorly characterized. The objective of this study was to measure the adhesion force between histatin 5, a primary AEP component, and hydroxyapatite (HA) surfaces. Both biotinylated histatin 5 and biotinylated human serum albumin were allowed to adsorb to streptavidin-coated silica microspheres attached to atomic force microscope (AFM) cantilevers. A multimode AFM with a Nanoscope IIIa controller was used to measure the adhesion force between protein-functionalized silica microspheres attached to cantilever tips and the HA surface. The imaging was performed in tapping mode with a Si3N4 AFM cantilever, while the adhesion forces were measured in AFM contact mode. A collection of force-distance curves (~3,000/replicate) was obtained to generate histograms from which the adhesion forces between histatin 5 or albumin and the HA surface were measured. We found that histatin 5 exhibited stronger adhesion forces (90% >1.830 nN) to the HA surface than did albumin (90% > 0.282 nN). This study presents an objective approach to adhesion force measurements between histatin 5 and HA, and provides the experimental basis for measuring the same parameters for other AEP constituents. Such knowledge will help in the design of synthetic proteins and peptides with preventive and therapeutic benefits for tooth enamel.

  2. Hydroxyapatite reinforced collagen scaffolds with improved architecture and mechanical properties.

    PubMed

    Kane, Robert J; Weiss-Bilka, Holly E; Meagher, Matthew J; Liu, Yongxing; Gargac, Joshua A; Niebur, Glen L; Wagner, Diane R; Roeder, Ryan K

    2015-04-01

    Hydroxyapatite (HA) reinforced collagen scaffolds have shown promise for synthetic bone graft substitutes and tissue engineering scaffolds. Freeze-dried HA-collagen scaffolds are readily fabricated and have exhibited osteogenicity in vivo, but are limited by an inherent scaffold architecture that results in a relatively small pore size and weak mechanical properties. In order to overcome these limitations, HA-collagen scaffolds were prepared by compression molding HA reinforcements and paraffin microspheres within a suspension of concentrated collagen fibrils (∼ 180 mg/mL), cross-linking the collagen matrix, and leaching the paraffin porogen. HA-collagen scaffolds exhibited an architecture with high porosity (85-90%), interconnected pores ∼ 300-400 μm in size, and struts ∼ 3-100 μm in thickness containing 0-80 vol% HA whisker or powder reinforcements. HA reinforcement enabled a compressive modulus of up to ∼ 1 MPa, which was an order of magnitude greater than unreinforced collagen scaffolds. The compressive modulus was also at least one order of magnitude greater than comparable freeze-dried HA-collagen scaffolds and two orders of magnitude greater than absorbable collagen sponges used clinically. Moreover, scaffolds reinforced with up to 60 vol% HA exhibited fully recoverable elastic deformation upon loading to 50% compressive strain for at least 100,000 cycles. Thus, the scaffold mechanical properties were well-suited for surgical handling, fixation, and bearing osteogenic loads during bone regeneration. The scaffold architecture, permeability, and composition were shown to be conducive to the infiltration and differentiation of adipose-derive stromal cells in vitro. Acellular scaffolds were demonstrated to induce angiogenesis and osteogenesis after subcutaneous ectopic implantation by recruiting endogenous cell populations, suggesting that the scaffolds were osteoinductive.

  3. Hydroxyapatite degradation and biocompatibility

    NASA Astrophysics Data System (ADS)

    Wang, Haibo

    Hydroxyapatite (HA) is widely used as a bioactive ceramics since it forms a chemical bonding to bone. The disadvantage of this material is its poor mechanical properties. HA can be degraded in body, which is the reason for its bioactivity, but too fast degradation rate could cause negative effects, such as macrophage present, particle generation, and even implant clinical failure. HA degradation rate will be greatly changed under many conditions: purity, HA form (i.e. bulk form, porous form, coating, or HA/polymer composites), microstructure, implant site, body conditions, etc. Although much work has been done in HA properties and application areas, the HA degradation behavior and mechanism under these different conditions are still not clear. In this research, three aspects of HA degradation have been studied: (1) Two very common impurities---Tri-Calcium Phosphate (TCP) and Calcium Oxide and their influences on HA degradation in vitro and in vivo, (2) influence of HA/polymer composite form on HA degradation, (3) HA material particle generation and related mechanism. From the in vitro and in vivo tests on bulk HA disks with various Ca/P ratios, HA degradation can clearly be found. The degradation level is different in different Ca/P ratio samples as well as in different test environments. In same test environment, non-stoichiometric HA samples have higher degradation rate than stoichiometric HA. HA/PMMA composite design successfully intensifies HA degradation both in vitro and in vivo. Grain boundary damage can be found on in vivo test samples, which has not been clearly seen on bulk HA degraded surface. HA particle generation is found in in vitro and in vivo HA/PMMA composite surface and in vivo bulk HA surface. Sintering temperature and time does affect HA grain size, and this affect HA degradation rate. Intergranular fracture is found in a several micron zone close to the Ca/P ratio 1.62 and 1.67 sample degraded surfaces. At Ca/P ratio greater than 1.667, after

  4. Crystallization of modified hydroxyapatite on titanium implants

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.; Zaits, A. V.

    2016-02-01

    Carbonated-hydroxyapatite (CHA) and Si-hydroxyapatite (Si-HA) precipitation have been synthesized from the model bioliquid solutions (synovial fluid and SBF). It is found that all the samples synthesized from the model solutions are single-phase and represent hydroxyapatite. The crystallization of the modified hydroxyapatite on alloys of different composition, roughness and subjected to different treatment techniques was investigated. Irradiation of the titanium substrates with the deposited biomimetic coating can facilitate further growth of the crystal and regeneration of the surface.

  5. Reaction of sodium calcium borate glasses to form hydroxyapatite.

    PubMed

    Han, Xue; Day, Delbert E

    2007-09-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape.

  6. HA Obtained by SGP and WCP

    NASA Astrophysics Data System (ADS)

    Guzmán Vázquez, Carolina; Piña Barba, Cristina

    2006-09-01

    Hydroxyapatite (HA) has been used as dental implant material and as bone replacement (in bone reconstruction). Ca/P molar ratio varies with the chemical process used, parameter could determine the clinic application. In the present work, HA was synthesized using the wet chemical process (WCP) and the sol-gel process (SGP). The efficiency of both chemical procedures was greater than 90%. HA by SGP was more crystalline and porous than WCP, also its cluster are further homogenous. The ICP-OES technique revealed that the HA by SGP was stoichiometric (Ca/P = 1.67). In meantime, the WCP had the molar ratio Ca/P = 1.56.

  7. Cementless Hydroxyapatite Coated Hip Prostheses

    PubMed Central

    Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

    2015-01-01

    More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality. PMID:25802848

  8. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1986-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  9. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  10. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1983-01-01

    Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  11. Osteogenic differentiation of cultured marrow stromal stem cells on surface of microporous hydroxyapatite based mica composite and macroporous synthetic hydroxyapatite.

    PubMed

    Nordström, E; Ohgushi, H; Yoshikawa, T; Yokobori, A T; Yokobori, T

    1999-01-01

    In order to investigate the significance of hydroxyapatite based microporous composite (HA/mica composite) surfaces and a macroporous synthetic hydroxyapatite, rat marrow cell culture, which shows osteogenic differentiation, was carried out on six different culture substrata (two control culture dishes, two identical HA/mica composites, and two identical macroporous synthetic hydroxyapatites). A culture period of two weeks in the presence of beta-glycerophosphate (BGP), ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain. The stain on the macroporous synthetic hydroxyapatite and the HA/mica composites were intense, the enzyme activity being about double that of control culture dishes. These data indicate that the synthetic macroporous hydroxyapatite surface and the HA/mica composite surface promotes osteoblastic differentiation.

  12. Nutrient-substituted hydroxyapatites: synthesis and characterization.

    PubMed

    Golden, D C; Ming, D W

    1999-01-01

    Incorporation of Mg, S, and plant-essential micronutrients into the structure of synthetic hydroxyapatite (HA) may be advantageous for closed-loop systems, such as will be required on Lunar and Martian outposts, because these apatites can be used as slow-release fertilizers. Our objective was to synthesize HA with Ca, P, Mg, S, Fe, Cu, Mn, Zn, Mo, B, and Cl incorporated into the structure, i.e., nutrient-substituted apatites. Hydroxyapatite, carbonate hydroxyapatite (CHA), nutrient-substituted hydroxyapatite (NHA), and nutrient-substituted carbonate hydroxyapatite (NCHA) were synthesized by precipitating from solution. Chemical and mineralogical analysis of precipitated samples indicated a considerable fraction of the added cations were incorporated into HA, without mineral impurities. Particle size of the HA was in the 1 to 40 nm range, and decreased with increased substitution of nutrient elements. The particle shape of HA was elongated in the c-direction in unsubstituted HA and NHA but more spherical in CHA and NCHA. The substitution of cations and anions in the HA structure was confirmed by the decrease of the d[002] spacing of HA with substitution of ions with an ionic radius less than that of Ca or P. The DTPA-extractable Cu ranged from 8 to 8429 mg kg-1, Zn ranged from 57 to 1279 mg kg-1, Fe from 211 to 2573 mg kg-1, and Mn from 190 to 1719 mg kg-1, depending on the substitution level of each element in HA. Nutrient-substituted HA has the potential to be used as a slow-release fertilizer to supply micronutrients, S, and Mg in addition to Ca and P.

  13. Nutrient-substituted hydroxyapatites: synthesis and characterization

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.

    1999-01-01

    Incorporation of Mg, S, and plant-essential micronutrients into the structure of synthetic hydroxyapatite (HA) may be advantageous for closed-loop systems, such as will be required on Lunar and Martian outposts, because these apatites can be used as slow-release fertilizers. Our objective was to synthesize HA with Ca, P, Mg, S, Fe, Cu, Mn, Zn, Mo, B, and Cl incorporated into the structure, i.e., nutrient-substituted apatites. Hydroxyapatite, carbonate hydroxyapatite (CHA), nutrient-substituted hydroxyapatite (NHA), and nutrient-substituted carbonate hydroxyapatite (NCHA) were synthesized by precipitating from solution. Chemical and mineralogical analysis of precipitated samples indicated a considerable fraction of the added cations were incorporated into HA, without mineral impurities. Particle size of the HA was in the 1 to 40 nm range, and decreased with increased substitution of nutrient elements. The particle shape of HA was elongated in the c-direction in unsubstituted HA and NHA but more spherical in CHA and NCHA. The substitution of cations and anions in the HA structure was confirmed by the decrease of the d[002] spacing of HA with substitution of ions with an ionic radius less than that of Ca or P. The DTPA-extractable Cu ranged from 8 to 8429 mg kg-1, Zn ranged from 57 to 1279 mg kg-1, Fe from 211 to 2573 mg kg-1, and Mn from 190 to 1719 mg kg-1, depending on the substitution level of each element in HA. Nutrient-substituted HA has the potential to be used as a slow-release fertilizer to supply micronutrients, S, and Mg in addition to Ca and P.

  14. Mechanical properties of hydroxyapatite/mica composite.

    PubMed

    Nordström, E G; Herø, H; Jørgensen, R B

    1994-01-01

    Bend specimens of the inorganic synthetic materials hydroxyapatite (HA) and a composite of hydroxyapatite/muscovite mica have been prepared and tested mechanically. Sintering followed by hot isostatic pressing (HIP) without encapsulation gave an increased strength for HA alone, but no significant increase in strength compared with sintering alone for HA/mica composites. The bend strength of the HA/mica composite was inferior to that of HA alone, the reason being inadequate bonding between HA and mica. HIP in glass capsules and an increased cold compaction pressure tended to improve the bend strength of the composite. Corrosion in tris for 7 d did not affect the bend strength of the investigated materials significantly.

  15. Nanofiber generation of hydroxyapatite and fluor-hydroxyapatite bioceramics.

    PubMed

    Kim, Hae-Won; Kim, Hyoun-Ee

    2006-05-01

    In this study, we produced hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) bioceramics as a novel geometrical form, the nanoscale fiber, for the biomedical applications. Based on the sol-gel precursors of the apatites, an electrospinning technique was introduced to generate nanoscale fibers. The diameter of the fibers was exploited in the range of a few micrometers to hundreds of nanometers (1.55 microm-240 nm) by means of adjusting the concentration of the sols. Through the fluoridation of apatite, the solubility of the fiber was tailored and the fluorine ions were well released from the FHA. The HA and FHA nanofibers produced in this study are considered to find potential applications in the biomaterials and tissue engineering fields.

  16. Fluorescent microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  17. Preparation and characterization of collagen-hydroxyapatite/pectin composite.

    PubMed

    Wenpo, Feng; Gaofeng, Liang; Shuying, Feng; Yuanming, Qi; Keyong, Tang

    2015-03-01

    Pectin, a kind of plant polysaccharide, was introduced into collagen-hydroxyapatite composite system, and prepared collagen-hydroxyapatite/pectin (Col-HA/pectin) composite in situ. The structure of the composite was investigated by XRD, SEM, and FT-IR. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity of the composite were investigated as well. The results show that the inorganic substance in the composite materials is hydroxyapatite in relatively low crystallinity. A new interface appeared by the interaction among hydroxyapatite and collagen-pectin, and formed smooth fine particles. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity indicate a potential use in bone replacement for the new composite.

  18. Femur bone repair in ovariectomized rats under the local action of alendronate, hydroxyapatite and the association of alendronate and hydroxyapatite

    PubMed Central

    Canettieri, Antonio Carlos Victor; Colombo, Carlos Eduardo Dias; Chin, Chung Man; Faig-Leite, Horácio

    2009-01-01

    An evaluation was made of the local action of alendronate sodium (A), hydroxyapatite (HA) and the association of both substances (A + HA), in different molar concentrations, on the femur bone repair of ovariectomized rats. Ninety-eight animals were divided into seven groups: control (C), starch (S), alendronate 1 mol (A1), alendronate 2 mols (A2), hydroxyapatite 1 mol (HA1), hydroxyapatite 2 mols (HA2) and the association of alendronate + hydroxyapatite (A + HA). Rats weighing about 250 g were ovariectomized and 2.5-mm diameter bone defects were made on the left femur 30 days later. Each experimental group had defects filled with appropriate material, except for group C (control). The animals were killed 7 and 21 days after surgery. Histological, histomorphometric and statistical analyses of bone neoformation in the bone defect site were performed. From the histological standpoint, the major differences occurred after 21 days. All specimens in groups C, S, HA1 and HA2 presented linear closure of the bone defect, and most animals in groups A1, A2 and A + HA showed no bone neoformation in the central area of the defect. No statistically significant difference was found among the experimental groups after 7 days; after 21 days, group HA2 presented the highest amount of neoformed bone. There was no significant difference among groups A1, A2 and A + HA in the two study periods. It was concluded that alendronate, either isolated or in association with hydroxyapatite, had an adverse effect on bone repair in this experimental model. Moreover, the hydroxyapatite used here proved to be biocompatible and osteoconductive, with group HA2 showing the best results. PMID:19765106

  19. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, R.M.

    A method and apparatus is disclosed for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  20. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, Russell M.

    1980-01-01

    A method and apparatus for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated to relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  1. Hybrid microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  2. Preparation of irregular mesoporous hydroxyapatite

    SciTech Connect

    Wang Hualin Zhai Linfeng; Li Yanhong; Shi Tiejun

    2008-06-03

    An irregular mesoporous hydroxyapatite (meso-HA), Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, is successfully prepared from Ca(NO{sub 3}){sub 2}.4H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} using surfactant cetyltrimethyl ammonium bromide (CTAB) as template. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results reveal that the positive head of CTAB is assembled on the surface precipitated HA and much NH{sub 4}{sup +} is enclosed in precipitated HA before calcination. Field scanning electron microscope (FSEM) reveals that there exist many interconnected pores throughout the HA reticular skeleton. Nitrogen adsorption-desorption experiment exhibits a mesoporous material type IV curve, and pore size distribution calculated from the desorption branch of the isotherms based on Barrett-Joyner-Halenda (BJH) model shows that most pores throughout the HA reticular skeleton are sized at about 40 nm, but the pores are not uniform on the whole, owning to decomposition of the 'organic' CTAB templating structures and ammonium salt enclosed in the precipitated HA. The specific surface area of irregular meso-HA is calculated to be 37.6 m{sup 2}/g according to the Brunauer-Emmett-Teller (BET) equation. Moreover, after polylactic acid/meso-HA (PLA/meso-HA) composites degraded 12 weeks in normal saline at 37 deg. C, the interconnected pores throughout the HA skeleton were enlarged and sized in micron degree, which resemble trabecular bone structure very much.

  3. Hydroxyapatite coatings.

    PubMed

    Lacefield, W R

    1988-01-01

    Four coating techniques were evaluated to determine which is most suitable for producing a dense, highly adherent coating onto metallic and ceramic implant materials. Two of the selected coating methods have serious limitations for use in this particular application, and did not meet the specified criteria for satisfactory coating as defined in the initial stages of the study. For example, the dip coating-sintering technique was judged to be unsatisfactory because of the adverse effect of the high-temperature sintering cycle on the mechanical properties of the metallic substrate materials. These materials could not be used in load-bearing applications because of the excessive grain growth and loss of the wrought structure of both the commercially pure Ti and Ti-6Al-4V substrates, and the loss of ductility in the cast Co-Cr-Mo alloy. Another area of concern was that bond strength between the HA coating and the substrate was not high enough to insure that interfacial failure would not occur during the lifetime of the implant. The immersion-coating technique, in which the metal substrate is immersed into the molten ceramic, was shown in a previous study to be the best method of coating a bioreactive glass onto a Co-Cr-Mo implant. Heating HA above its melting temperature, however, caused undesired compositional and structural changes, and upon solidification very limited adherence between the modified ceramic and substrate material occurred under the conditions of this study. The HIP technique, in which the Ti powder substrate and the HA powder coating are sintered together in a high-pressure autoclave, shows great promise for the fabrication of high-quality composite implants. Initial studies have indicated that high-density Ti substrates with a small grain size that are well bonded to a dense HA coating can be produced under optimum conditions. Sintering and densification additives, such as SiO2 powder, do not appear to be necessary. The main drawback to this

  4. The mechanical properties and osteoconductivity of hydroxyapatite bone scaffolds with multi-scale porosity.

    PubMed

    Woodard, Joseph R; Hilldore, Amanda J; Lan, Sheeny K; Park, C J; Morgan, Abby W; Eurell, Jo Ann C; Clark, Sherrie G; Wheeler, Matthew B; Jamison, Russell D; Wagoner Johnson, Amy J

    2007-01-01

    The relative osteoconductivity and the change in the mechanical properties of hydroxyapatite (HA) scaffolds with multi-scale porosity were compared to scaffolds with a single pore size. Non-microporous (NMP) scaffolds contained only macroporosity (250-350 microm) and microporous (MP) scaffolds contained both macroporosity and microporosity (2-8 microm). Recombinant human bone morphogenetic protein-2 (rhBMP-2) was incorporated into all scaffolds via gelatin microspheres prior to implantation into the latissimus dorsi muscle of Yorkshire pigs. After 8 weeks, only the MP scaffolds contained bone. The result demonstrates the efficacy of the MP scaffolds as drug carriers. Implanted and as-fabricated scaffolds were compared using histology, microcomputed tomography, scanning electron microscopy, and compression testing. Implanted scaffolds exhibited a stress-strain response similar to that of cancellous bone with strengths between those of cancellous and cortical bone. The strength and stiffness of implanted NMP scaffolds decreased by 15% and 46%, respectively. Implanted MP scaffolds lost 30% of their strength and 31% of their stiffness. Bone arrested crack propagation effectively in MP scaffolds. The change in mechanical behavior is discussed and the study demonstrates the importance of scaffold microporosity on bone ingrowth and on the mechanical behavior of HA implant materials.

  5. Cell responses and hemocompatibility of g-HA/PLA composites.

    PubMed

    Li, Jia; Zheng, Wei; Zheng, Yufeng; Lou, Xia

    2011-04-01

    The objective of this study was to investigate the hemocompatibility and cell responses to some novel poly(L-lactide) (PLA) composites containing surface modified hydroxyapatite particles for potential applications as a bone substitute material. The surface of hydroxyapatite (HA) particles was first grafted with L-lactic acid oligomers to form grafted HA (g-HA) particles. The g-HA particles were further blended with PLA to prepare g-HA/PLA composites. Our previous study has shown significant improvement in tensile properties of these materials due to the enhanced interfacial adhesion between the polymer matrix and HA particles. To further investigate the potential applications of these composites in bone repair and other orthopedic surgeries, a series of in vitro and in vivo experiments were conducted to examine the cell responses and hemocompatibility of the materials. In vitro experiments showed that the g-HA/PLA composites were well tolerated by the L-929 cells. Hemolysis of the composites was lower than that of pure PLA. Subcutaneous implantation demonstrated that the g-HA/PLA composites were more favorable than the control materials for soft tissue responses. The results suggested that the g-HA/PLA composites are promising and safe materials with potential applications in tissue engineering.

  6. Pitch carbon microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Nelson, J. B.

    1977-01-01

    Petroleum pitch carbon microspheres were prepared by flash heating emulsified pitch and carbonizing the resulting microspheres in an inert atmosphere. Microsphere composites were obtained from a mixture of microspheres and tetraester precursor pyrrone powder. Scanning electron micrographs of the composite showed that it was an aggregate of microspheres bonded together by the pyrrone at the sphere contact points, with voids in and among the microspheres. Physical, thermal, and sorption properties of the composite are described. Composite applications could include use as a honeycomb filler in elevated-temperature load-bearing sandwich boards or in patient-treatment tables for radiation treatment of tumors.

  7. Cytotoxicity of hydroxyapatite, fluorapatite and fluor-hydroxyapatite: a comparative in vitro study.

    PubMed

    Theiszova, M; Jantova, S; Letasiova, S; Palou, M; Cipak, L

    2008-01-01

    The purpose of this study was to evaluate the cytotoxicity of two formulations of hydroxyapatite (HA), namely fluorapatite (FA) and fluor-hydroxyapatite (FHA). HA is used as carrier material for antibiotics or anticancer drugs during treatment of bone metastasis. Negative control, represented by HA, was included for comparative purposes. Leukemia cells were used as a model cell line, and the effect of eluates of tested biomaterials on cell proliferation/viability and mechanism of antiproliferative activity were assessed. Study design attempted to reveal the toxicity of tested biomaterials with an emphasis to decide if tested biomaterials have promise for further studies in vivo. Results showed that eluates of FA and FHA inhibit the growth of leukemia cells and induce programmed cell death through mitochondrial/caspase-9/caspase-3-dependent pathway. Due to these differences compare to HA, it is concluded that FA and FHA have promise for evaluation of their behaviour in vivo.

  8. Room Temperature Crystallization of Hydroxyapatite in Porous Silicon Structures.

    PubMed

    Santana, M; Estevez, J O; Agarwal, V; Herrera-Becerra, R

    2016-12-01

    Porous silicon (PS) substrates, with different pore sizes and morphology, have been used to crystallize hydroxyapatite (HA) nano-fibers by an easy and economical procedure using a co-precipitation method at room temperature. In situ formation of HA nanoparticles, within the meso- and macroporous silicon structure, resulted in the formation of nanometer-sized hydroxyapatite crystals on/within the porous structure. The X-ray diffraction technique was used to determine the tetragonal structure of the crystals. Analysis/characterization demonstrates that under certain synthesis conditions, growth and crystallization of hydroxyapatite layer on/inside PS can be achieved at room temperature. Such composite structures expand the possibility of designing a new bio-composite material based on the hydroxyapatite and silicon synthesized at room temperature.

  9. Characterisation of Suspension Precipitated Nanocrystalline Hydroxyapatite Powders

    NASA Astrophysics Data System (ADS)

    Mallik, P. K.; Swain, P. K.; Patnaik, S. C.

    2016-02-01

    Hydroxyapatite (HA) is a well-known biomaterial for coating on femoral implants, filling of dental cavity and scaffold for tissue replacement. Hydroxyapatite possess limited load bearing capacity due to their brittleness. In this paper, the synthesis of nanocrystalline hydroxyapatite powders was prepared by dissolving calcium oxide in phosphoric acid, followed by addition of ammonia liquor in a beaker. The prepared solution was stirred by using magnetic stirrer operated at temperature of 80°C for an hour. This leads to the formation of hydroxyapatite precipitate. The precipitate was dried in oven for overnight at 100°C. The dried agglomerated precipitate was calcined at 800°C in conventional furnace for an hour. The influence of calcium oxide concentration and pH on the resulting precipitates was studied using BET, XRD and SEM. As result, a well-defined sub-rounded morphology of powders size of ∼41 nm was obtained with a salt concentration of 0.02 M. Finally, it can be concluded that small changes in the reaction conditions led to large changes in final size, shape and degree of aggregation of the hydroxyapatite particles.

  10. Influence of Barium Hexaferrite on Magnetic Properties of Hydroxyapatite Ceramics.

    PubMed

    Jarupoom, P; Jaita, P

    2015-11-01

    Hydroxyapatite (HA) powders was derived from natural bovine bone by sequence of thermal processes. The barium hexaferrite (BF) find magnetic powders were added into HA powders in ratio of 1-3 vol.%. The HA-BF ceramics were prepared by a solid state reaction method and sintered at 1250 degrees C for 2 h. Effects of BF additive on structural, physical and magnetic properties of HA ceramics were investigated. X-ray diffraction revealed that all HA-BF samples showed a main phase of high purity hydroxyapatite [Ca10(PO4)6(OH)2] with calcium and phosphate molar ratio of 1.67. The addition of BF into HA inhibited grain growth and caused an improvement of mechanical properties. The M-H hysteresis loops also showed an improvement in magnetic behavior for higher content of BF. Moreover, in vitro bioactivity test indicated that the 2-3 vol.% sample may be suitable for biological applications.

  11. microsphere assemblies

    NASA Astrophysics Data System (ADS)

    Peña-Flores, Jesús I.; Palomec-Garfias, Abraham F.; Márquez-Beltrán, César; Sánchez-Mora, Enrique; Gómez-Barojas, Estela; Pérez-Rodríguez, Felipe

    2014-09-01

    The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases.

  12. Development of model hydroxyapatite bone scaffolds with multiscale porosity for potential load bearing applications

    NASA Astrophysics Data System (ADS)

    Dellinger, Jennifer Gwynne

    2005-11-01

    Model hydroxyapatite (HA) bone scaffolds consisting of a latticed pattern of rods were fabricated by a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes. An optimal HA paste formulation for this method was developed. Local porosity, i.e. microporosity (1--30 mum) and sintering porosity (less than 1 mum), were produced by including polymer microsphere porogens in the HA pastes and by controlling the sintering of the scaffolds. Scaffolds with and without local porosity were evaluated with and without in vitro accelerated degradation. Percent weight loss of the scaffolds and calcium and phosphorus concentrations in solution increased with degradation time. After degradation, compressive strength and modulus decreased significantly for scaffolds with local porosity, but did not change significantly for scaffolds without local porosity. The compressive strength and modulus of scaffolds without local porosity were comparable to human cortical bone and were significantly greater than the scaffolds with local porosity. Micropores in HA disks caused surface pits that increased the surface roughness as compared to non-microporous HA disks. Mouse mesenchymal stem cells extended their cell processes into these microporous pits on HA disks in vitro. ALP expression was prolonged, cell attachment strength increased, and ECM production appeared greater on microporous HA disks compared to non-microporous HA disks and tissue culture treated polystyrene controls. Scaffolds with and without microporosity were implanted in goats bones. Microporous scaffolds with rhBMP-2 increased the percent of the scaffold filled with bone tissue compared to microporous scaffolds without rhBMP-2. Lamellar bone inside scaffolds was aligned near the rods junctions whereas lamellar bone was aligned in a more random configuration away from the rod junctions. Microporous scaffolds stained darkly with toluidine blue beneath areas of contact with new bone. This

  13. Removal of Uranium in Drinking Water: Brimac Environmental Services, Inc. Brimac HA 216 Adsorptive Media

    EPA Science Inventory

    The Brimac HA 216 Adsorptive Media was tested for uranium (U) removal from a drinking water source (well water) at Grappone Toyota located in Bow, New Hampshire. The HA 216 media is a hydroxyapatite-based material. A pilot unit, consisting of a TIGG Corporation Cansorb® C-5 ste...

  14. Preparation of bioactive porous HA/PCL composite scaffolds

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Guo, L. Y.; Yang, X. B.; Weng, J.

    2008-12-01

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications.

  15. In situ deposition of hydroxyapatite on graphene nanosheets

    SciTech Connect

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2013-02-15

    Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH{sub 4} etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

  16. Hydroxyapatite surface-induced peptide folding.

    PubMed

    Capriotti, Lisa A; Beebe, Thomas P; Schneider, Joel P

    2007-04-25

    Herein, we describe the design and surface-binding characterization of a de novo designed peptide, JAK1, which undergoes surface-induced folding at the hydroxyapatite (HA)-solution interface. JAK1 is designed to be unstructured in buffered saline solution, yet undergo HA-induced folding that is largely governed by the periodic positioning of gamma-carboxyglutamic acid (Gla) residues within the primary sequence of the peptide. Circular dichroism (CD) spectroscopy and analytical ultracentrifugation indicate that the peptide remains unfolded and monomeric in solution under normal physiological conditions; however, CD spectroscopy indicates that in the presence of hydroxyapatite, the peptide avidly binds to the mineral surface adopting a helical structure. Adsorption isotherms indicate nearly quantitative surface coverage and Kd = 310 nM for the peptide-surface binding event. X-ray photoelectron spectroscopy (XPS) coupled with the adsorption isotherm data suggests that JAK1 binds to HA, forming a self-limiting monolayer. This study demonstrates the feasibility of using HA surfaces to trigger the intramolecular folding of designed peptides and represents the initial stages of defining the design rules that allow HA-induced peptide folding.

  17. Preparation and characterization of bio-composite PEEK/nHA

    NASA Astrophysics Data System (ADS)

    Jin, Y. S.; Bian, C. C.; Zhang, Z. Q.; Zhao, Y.; Yang, L.

    2017-01-01

    PEEK/nHA composite material, with excellent mechanical property as polyetheretherketone (PEEK) and biological activity as hydroxyapatite (HA), has attracted wide attention of medical experts and materials science experts. The addition of hydroxyapatite was the decisive factor for biological activity in PEEK/nHA composite. In this paper, acicular nanohydroxyapatite was prepared by chemical precipitation method with Ca(NO3)2, (NH4)2HPO4 as raw material; PEEK/nHA composite was prepared by solution blending and vacuum sintering method. The composite was characterized with FT-IR, XRD, DSC, TG and mechanical property test. Results showed that the composite has good thermal stability and compressive property when the mass ratio of PEEK to nHA is 10:3; and high nHA content can improve the biological activity of the composite, which can meet the basic requirements for bone tissue engineering scaffold.

  18. Impact behavior of hydroxyapatite reinforced polyethylene composites.

    PubMed

    Zhang, Y; Tanner, K E

    2003-01-01

    Hydroxyapatite particulate reinforced high density polyethylene composite (HA-HDPE) has been developed as a bone replacement material. The impact behavior of the composites at 37 degrees C has been investigated using an instrumented falling weight impact testing machine. The fracture surfaces were examined using SEM and the fracture mechanisms are discussed. It was found that the fracture toughness of HA-HDPE composites increased with HDPE molecular weight, but decreased with increasing HA volume fraction. Examination of fracture surfaces revealed weak filler/matrix interfaces which can debond easily to enable crack initiation and propagation. Increasing HA volume fraction increases the interface area, and more cracks can form and develop, thus decreasing the impact resistance of the composites. Another important factor for the impact behavior of the composites is the matrix. At higher molecular weight, HDPE is able to sustain more plastic deformation and dissipates more impact energy, hence improving the impact property.

  19. Cement from magnesium substituted hydroxyapatite.

    PubMed

    Lilley, K J; Gbureck, U; Knowles, J C; Farrar, D F; Barralet, J E

    2005-05-01

    Brushite cement may be used as a bone graft material and is more soluble than apatite in physiological conditions. Consequently it is considerably more resorbable in vivo than apatite forming cements. Brushite cement formation has previously been reported by our group following the mixture of nanocrystalline hydroxyapatite and phosphoric acid. In this study, brushite cement was formed from the reaction of nanocrystalline magnesium-substituted hydroxyapatite with phosphoric acid in an attempt to produce a magnesium substituted brushite cement. The presence of magnesium was shown to have a strong effect on cement composition and strength. Additionally the presence of magnesium in brushite cement was found to reduce the extent of brushite hydrolysis resulting in the formation of HA. By incorporating magnesium ions in the apatite reactant structure the concentration of magnesium ions in the liquid phase of the cement was controlled by the dissolution rate of the apatite. This approach may be used to supply other ions to cement systems during setting as a means to manipulate the clinical performance and characteristics of brushite cements.

  20. Porous hydroxyapatite-gelatin composites with functions of bone substitutes and drug releasing agents: A preliminary study

    NASA Astrophysics Data System (ADS)

    Sopyan, I.; Sulaiman, N. S.; Gustiono, D.; Herdianto, N.

    2006-01-01

    Biomedical composites made of porous hydroxyapatite (HA) bonded with a biodegradable polymeric matrix gelatin have been prepared. This device is expected to be useful as an excellent bone graft with bioactive hydroxyapatite which will facilitate new bone formation and at the same time it could functions as drug delivery with a controlled release rate. In this preliminary report, we wish to present preparation and physical characterization of the biomedical composite and the non-biodegradable porous hydroxyapatite composing the matrix of the composite. Porous hydroxyapatite was prepared via polymeric sponge method using hydroxyapatite nanopowders which were prepared via sol-gel procedure. Suspensions of the sol-gel derived hydroxyapatite powder was prepared with an adjusted loading of hydroxyapatite, using a dispersant. After soaking cellulosic sponges into the suspension, the sponges were dried and then subjected to heat-treatment at 600°C, followed by sintering at 1250°C for 1h. Three types of porous hydroxyapatite samples have been prepared in various composition of hydroxyapatite suspension. Porous hydroxyapatite bodies produced from slurry with less hydroxyapatite powder content and more dispersant amount yielded higher porosity and thus causing weaker compressive strength. Compressive strengths varied between 0.67 and 1.94 MPa depending on the porosity of the sample. Porosity plays important role in gelatin loading; the amount of gelatin coated on the porous hydroxyapatite bodies depend on porosity and the gelatin concentration in water solution. The higher porosity the more gelatin can be absorbed by the porous body.

  1. Hydroxyapatite formation from cuttlefish bones: kinetics.

    PubMed

    Ivankovic, H; Tkalcec, E; Orlic, S; Ferrer, G Gallego; Schauperl, Z

    2010-10-01

    Highly porous hydroxyapatite (Ca(10)(PO(4))(6)·(OH)(2), HA) was prepared through hydrothermal transformation of aragonitic cuttlefish bones (Sepia officinalis L. Adriatic Sea) in the temperature range from 140 to 220°C for 20 min to 48 h. The phase composition of converted hydroxyapatite was examined by quantitative X-ray diffraction (XRD) using Rietveld structure refinement and Fourier transform infrared spectroscopy (FTIR). Johnson-Mehl-Avrami (JMA) approach was used to follow the kinetics and mechanism of transformation. Diffusion controlled one dimensional growth of HA, predominantly along the a-axis, could be defined. FTIR spectroscopy determined B-type substitutions of CO(3) (2-) groups. The morphology and microstructure of converted HA was examined by scanning electron microscopy. The general architecture of cuttlefish bones was preserved after hydrothermal treatment and the cuttlefish bones retained its form with the same channel size (~80 × 300 μm). The formation of dandelion-like HA spheres with diameter from 3 to 8 μm were observed on the surface of lamellae, which further transformed into various radially oriented nanoplates and nanorods with an average diameter of about 200-300 nm and an average length of about 8-10 μm.

  2. Development of biomimetic nano-hydroxyapatite/poly(hexamethylene adipamide) composites.

    PubMed

    Wang, Xuejiang; Li, Yubao; Wei, Jie; de Groot, Klass

    2002-12-01

    In this study, acicular nano-hydroxyapatite (n-HA) was used to make a new biomimetic composite with polyamide (poly hexamethylene adipamide) by a unique technique. The physical and chemical characteristics of the composites were tested. It was found that these synthesized n-HA crystals were similar to bone apatite in size, phase composition and crystal structure. The biomimetic n-HA crystals were uniformly distributed in the polymer matrix and its content can reach 65%, close to that in natural bone. Chemical binding between inorganic n-HA and polyamide was investigated and discussed. The mechanical properties of the composites were found to match well with those of natural bone.

  3. Novel nanostructured hydroxyapatite coating for dental and orthopedic implants

    NASA Astrophysics Data System (ADS)

    Liu, Huinan; Jiang, Wenping; Malshe, Ajay

    2009-09-01

    A novel hybrid coating process, combining NanoSpray® (built on electrostatic spray coating) technology with microwave sintering process, was developed for synthesizing hydroxyapatite- (HA-) based nanostructured coating with favorable properties for dental and orthopedic implants. Specifically, HA nanoparticles were deposited on commercially pure titanium substrates using NanoSpray technique to produce the HA coating, which was then sintered in a microwave furnace under controlled conditions. The study showed that the use of NanoSpray followed by microwave sintering results in nanoscale HA coating for dental/orthopedic application.

  4. Making Polymeric Microspheres

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  5. Fracture properties of bioabsorbable HA/PLLA/PCL composite material

    NASA Astrophysics Data System (ADS)

    Park, S. D.; Todo, M.; Arakawa, K.; Tsuji, H.; Takenoshita, Y.

    2005-04-01

    Hydroxyapatite particle filled poly(L-lactic acid)/poly(e-caprolactone) blend (HA/PLLA/PCL) composite materials were developed by melt-mixing, and their bending mechanical properties and fracture toughness were examined. It was found that the fracture absorbed energy and fracture toughness are maximized with the PCL content of 5wt%. Local plastic deformation of PLLA/PCL matrix is the main mechanism of energy dissipation during fracture. This ductile deformation is considered to be initiated in the surroundings of voids formed due to interfacial debonding at HA/matrix interfaces and phase separation of PLLA and PCL. On the other hand, fracture toughness of HA/PLLA/PCL with the PCL contents of 10 and 15wt% becomes lower than that of HA/PLLA. In these composites, void formation causes severe local stress concentration and therefore degrades the materials rather than improving the fracture resistance.

  6. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  7. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  8. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  9. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  10. Micro- and nano-hydroxyapatite as active reinforcement for soft biocomposites.

    PubMed

    Munarin, F; Petrini, P; Gentilini, R; Pillai, R S; Dirè, S; Tanzi, M C; Sglavo, V M

    2015-01-01

    Pectin-based biocomposite hydrogels were produced by internal gelation, using different hydroxyapatite (HA) powders from commercial source or synthesized by the wet chemical method. HA possesses the double functionality of cross-linking agent and inorganic reinforcement. The mineralogical composition, grain size, specific surface area and microstructure of the hydroxyapatite powders are shown to strongly influence the properties of the biocomposites. Specifically, the grain size and specific surface area of the HA powders are strictly correlated to the gelling time and rheological properties of the hydrogels at room temperature. Pectin pH is also significant for the formation of ionic cross-links and therefore for the hydrogels stability at higher temperatures. The obtained results point out that micrometric-size hydroxyapatite can be proposed for applications which require rapid gelling kinetics and improved mechanical properties; conversely the nanometric hydroxyapatite synthesized in the present work seems the best choice to obtain homogeneous hydrogels with more easily controlled gelling kinetics.

  11. Controlled, sustained release of proteins via an injectable, mineral-coated microsphere delivery vehicle

    NASA Astrophysics Data System (ADS)

    Franklin-Ford, Travelle

    Hydroxyapatite interfaces have demonstrated strong protein binding and protein selection from a passing solution and can serve as a biocompatible carrier for controlled protein delivery. Hydroxyapatite is a major component of long bones and tooth enamel and is the most stable of all calcium phosphate isoforms in aqueous solutions at physiologic pH, providing a sensitive chromatographic mechanism for separating proteins. Here we describe an approach to create a synthetic hydroxyapatite coating through a biomimetic, heterogeneous nucleation from a modified simulated body fluid--supersaturated with calcium and phosphate ions on the surface of injectable polymer microspheres. We are able to bind and release bioactive growth factors into a variety of in vitro and in vivo conditions, demonstrating the functionality and advantage of the biomaterial. Creating a hydroxyapatite layer on the Poly(D,L-lactide-co-glycolide) (PLG) microsphere surface, avails the microsphere interior for another application that will not compete with protein binding and release. Encapsulating an imaging agent within the aqueous phase of the emulsion provides a visual reference for the injectable therapy upon microsphere fabrication. Another advantage of this system is that the mineral coating and subsequent protein binding is not compromised by the encapsulated imaging agent. This dual function delivery vehicle is not only advantageous for spatial tracking therapeutic applications, but also determining the longevity of the delivery vehicle once injected. In the broader sense, providing a mechanism to image and track our temporally controlled, sustained delivery system gives more evidence to support the effects of released protein on in vivo responses (bioactivity) and locate microspheres within different biological systems.

  12. Suspension thermal spraying of hydroxyapatite: microstructure and in vitro behaviour.

    PubMed

    Bolelli, Giovanni; Bellucci, Devis; Cannillo, Valeria; Lusvarghi, Luca; Sola, Antonella; Stiegler, Nico; Müller, Philipp; Killinger, Andreas; Gadow, Rainer; Altomare, Lina; De Nardo, Luigi

    2014-01-01

    In cementless fixation of metallic prostheses, bony ingrowth onto the implant surface is often promoted by osteoconductive plasma-sprayed hydroxyapatite coatings. The present work explores the use of the innovative High Velocity Suspension Flame Spraying (HVSFS) process to coat Ti substrates with thin homogeneous hydroxyapatite coatings. The HVSFS hydroxyapatite coatings studied were dense, 27-37μm thick, with some transverse microcracks. Lamellae were sintered together and nearly unidentifiable, unlike conventional plasma-sprayed hydroxyapatite. Crystallinities of 10%-70% were obtained, depending on the deposition parameters and the use of a TiO2 bond coat. The average hardness of layers with low (<24%) and high (70%) crystallinity was ≈3.5GPa and ≈4.5GPa respectively. The distributions of hardness values, all characterised by Weibull modulus in the 5-7 range, were narrower than that of conventional plasma-sprayed hydroxyapatite, with a Weibull modulus of ≈3.3. During soaking in simulated body fluid, glassy coatings were progressively resorbed and replaced by a new, precipitated hydroxyapatite layer, whereas coatings with 70% crystallinity were stable up to 14days of immersion. The interpretation of the precipitation behaviour was also assisted by surface charge assessments, performed through Z-potential measurements. During in vitro tests, HA coatings showed no cytotoxicity towards the SAOS-2 osteoblast cell line, and surface cell proliferation was comparable with proliferation on reference polystyrene culture plates.

  13. Improvement of the stability of hydroxyapatite through glass ceramic reinforcement.

    PubMed

    Ha, Na Ra; Yang, Zheng Xun; Hwang, Kyu Hong; Kim, Tae Suk; Lee, Jong Kook

    2010-05-01

    Hydroxyapatite has achieved significant application in orthopedic and dental implants due to its excellent biocompatibility. Sintered hydroxyapatites showed significant dissolution, however, after their immersion in water or simulated body fluid (SBF). This grain boundary dissolution, even in pure hydroxyapatites, resulted in grain separation at the surfaces, and finally, in fracture. In this study, hydroxyapatite ceramics containing apatite-wollastonite (AW) or calcium silicate (SG) glass ceramics as additives were prepared to prevent the dissolution. AW and SG glass ceramics were added at 0-7 wt% and powder-compacted uniaxially followed by firing at moisture conditions. The glass phase was incorporated into the hydroxyapatite to act as a sintering aid, followed by crystallization, to improve the mechanical properties without reducing the biocompatibility. As seen in the results of the dissolution test, a significant amount of damage was reduced even after more than 14 days. TEM and SEM showed no decomposition of HA to the secondary phase, and the fracture toughness increased, becoming even higher than that of the commercial hydroxyapatite.

  14. Nanostructured nickel-free austenitic stainless steel/hydroxyapatite composites.

    PubMed

    Tulinski, Maciej; Jurczyk, Mieczyslaw

    2012-11-01

    In this work Ni-free austenitic stainless steels with nanostructure and their nanocomposites with hydroxyapatite are presented and characterized by means of X-ray diffraction and optical profiling. The samples were synthesized by mechanical alloying, heat treatment and nitriding of elemental microcrystalline powders with addition of hydroxyapatite (HA). In our work we wanted to introduce into stainless steel hydroxyapatite ceramics that have been intensively studied for bone repair and replacement applications. Such applications were chosen because of their high biocompatibility and ability to bond to bone. Since nickel-free austenitic stainless steels seem to have better mechanical properties, corrosion resistance and biocompatibility compared to 316L stainless steels, it is possible that composite made of this steel and HA could improve properties, as well. Mechanical alloying and nitriding are very effective technologies to improve the corrosion resistance of stainless steel. Similar process in case of nanocomposites of stainless steel with hydroxyapatite helps achieve even better mechanical properties and corrosion resistance. Hence nanocrystalline nickel-free stainless steels and nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants, e.g., orthopedic implants. In such application, the surface roughness and more specifically the surface topography influences the proliferation of cells (e.g., osteoblasts).

  15. Thermal Diffusivity in Bone and Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Calderón, A.; Peña Rodríguez, G.; Muñoz Hernández, R. A.; Díaz Gongora, J. A. I.; Mejia Barradas, C. M.

    2004-09-01

    We report thermal diffusivity measurements in bull bone and commercial hydroxyapatite (HA), both in powder form, in order to determinate the thermal compatibility between these materials. Besides this, we report a comparison between these measured values and those of metallic samples frequently used in implants, as high purity titanium and stainless steel. Our results show a good thermal compatibility (74%) between HA and bone, both in powder form. Finally, it was obtained a one order of magnitude difference between the thermal diffusivity values of metallic samples and those corresponding values to bone and HA being this difference greater in titanium than in stainless steel, which is important to consider in some biomedical and dental applications.

  16. First principles study of hydroxyapatite surface

    NASA Astrophysics Data System (ADS)

    Slepko, Alexander; Demkov, Alexander A.

    2013-07-01

    The biomineral hydroxyapatite (HA) [Ca10(PO4)6(OH)2] is the main mineral constituent of mammal bone. We report a theoretical investigation of the HA surface. We identify the low energy surface orientations and stoichiometry under a variety of chemical environments. The surface most stable in the physiologically relevant OH-rich environment is the OH-terminated (1000) surface. We calculate the work function of HA and relate it to the surface composition. For the lowest energy OH-terminated surface we find the work function of 5.1 eV, in close agreement with the experimentally reported range of 4.7 eV-5.1 eV [V. S. Bystrov, E. Paramonova, Y. Dekhtyar, A. Katashev, A. Karlov, N. Polyaka, A. V. Bystrova, A. Patmalnieks, and A. L. Kholkin, J. Phys.: Condens. Matter 23, 065302 (2011), 10.1088/0953-8984/23/6/065302].

  17. First principles study of hydroxyapatite surface.

    PubMed

    Slepko, Alexander; Demkov, Alexander A

    2013-07-28

    The biomineral hydroxyapatite (HA) [Ca10(PO4)6(OH)2] is the main mineral constituent of mammal bone. We report a theoretical investigation of the HA surface. We identify the low energy surface orientations and stoichiometry under a variety of chemical environments. The surface most stable in the physiologically relevant OH-rich environment is the OH-terminated (1000) surface. We calculate the work function of HA and relate it to the surface composition. For the lowest energy OH-terminated surface we find the work function of 5.1 eV, in close agreement with the experimentally reported range of 4.7 eV-5.1 eV [V. S. Bystrov, E. Paramonova, Y. Dekhtyar, A. Katashev, A. Karlov, N. Polyaka, A. V. Bystrova, A. Patmalnieks, and A. L. Kholkin, J. Phys.: Condens. Matter 23, 065302 (2011)].

  18. Bacterial adhesion to bisphosphonate coated hydroxyapatite.

    PubMed

    Ganguli, A; Steward, C; Butler, S L; Philips, G J; Meikle, S T; Lloyd, A W; Grant, M H

    2005-04-01

    Staphylococcus aureus (S. aureus) is commonly associated with microbial infection of orthopaedic implants. Such infections often lead to osteomyelitis, which may result in failure of the implant due to localised bone destruction. Bacterial adhesion and subsequent colonisation of the device may occur as a consequence of contamination during surgery, or by seeding from a distant site through the blood circulation. Coating of the hydroxyapatite (HA) ceramic component of artificial hip joints with the bisphosphonates clodronate (C) and pamidronate (P) has been proposed as a means to minimise osteolysis and thereby prevent loosening of the implant. However, the effect of the bisphosphonate coating on bacterial adhesion to the HA materials must be determined before this approach can be implemented. In this study coated HA materials were incubated with the S. aureus and the number of adherent bacteria determined using the Modified Vortex Device (MVD) method. The number of bacteria adherent to the P coated HA material was significantly greater than that adherent to uncoated HA (60-fold increase) or to the C coated HA (90-fold increase). Therefore, even though earlier studies suggested that P bound to HA may improve osseointegration, the results presented would suggest that the use of this coating may be limited by the potential increased susceptibility of the coated device to infection.

  19. Pulsed laser deposition of hydroxyapatite film on laser gas nitriding NiTi substrate

    NASA Astrophysics Data System (ADS)

    Yang, S.; Xing, W.; Man, H. C.

    2009-09-01

    A hydroxyapatite (HA) film was deposited on laser gas nitriding (LGN) NiTi alloy substrate using pulsed laser deposition technique. TiN dendrite prepared by LGN provided a higher number of nucleation sites for HA film deposition, which resulted in that a lot number of HA particles were deposited on TiN dendrites. Moreover, the rough LGN surface could make the interface adhesive strength between HA film and substrate increase as compared with that on bare NiTi substrate.

  20. Microstructural disintegration in dense hydroxyapatite and hydroxyapatite-coated metal implants

    NASA Astrophysics Data System (ADS)

    Seo, Dong Seok; Lee, Jong Kook

    2007-08-01

    Hydroxyapatite (HA) has been widely used as a coating for orthopedic metal implants. An important concern regarding HA coating is its degradation of the biological milieu. In this study, the microstructure of a retrieved HA-coated acetabular cup implanted for four years after total hip arthroplasty (THA) was investigated by field emission scanning electron microscopy. In order to understand the underlying mechanism, of degradation and exfoliation of the HA coating, degradation of phase-pure and dense HA ceramics was also observed by in vitro and in vivo testing. The surface morphology and fracture surfaces of HA ceramics revealed that the dissolution starting at the surface extended inwards resulting in particle loosening and microstructural-level degradation. The dissolution features of HA ceramics were similar to the case of HA coating. It was found that extensive dissolution of the coating occurred and most of the coating disappeared. The majority of the remaining graints were fractured by the intergranular mode, suggesting that grain boundaries should be predominantly dissolved. These observations may explain the mechanism through which the biological stability of the HA coated layer becomes unexpectedly poor.

  1. Microsphere Insulation Panels

    NASA Technical Reports Server (NTRS)

    Mohling, R.; Allen, M.; Baumgartner, R.

    2006-01-01

    Microsphere insulation panels (MIPs) have been developed as lightweight, longlasting replacements for the foam and vacuum-jacketed systems heretofore used for thermally insulating cryogenic vessels and transfer ducts. The microsphere core material of a typical MIP consists of hollow glass bubbles, which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials. In particular, a core filling of glass microspheres has high crush strength and low density, is noncombustible, and performs well in soft vacuum.

  2. Hydroxyapatite with environmental applications

    SciTech Connect

    Popa, C. L.; Ciobanu, C. S.; Predoi, D.; Petre, C. C.; Jiga, G.; Motelica-Heino, M.; Iconaru, S. L.

    2014-05-15

    The aim of this study was to synthetize new nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp) for lead removal in aqueous solutions. The morphological and compositional analysis of MTHAp was investigated by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Removal experiments of Pb{sup 2+} ions were carried out in aqueous solutions with controlled concentration of Pb{sup 2+} and at fixed pH of 5. After the removal experiment of Pb{sup 2+} ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp-5 via the adsorption of Pb{sup 2+} ions followed by a cation exchange reaction. Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb{sup 2+} ions from aqueous solution.

  3. Effect of modification substrate on the microstructure of hydroxyapatite coating

    NASA Astrophysics Data System (ADS)

    Realpe-Jaramillo, J.; Morales-Morales, J. A.; González-Sánchez, J. A.; Cabanzo, R.; Mejía-Ospino, E.; Rodríguez-Pereira, J.

    2017-01-01

    Bioactive hydroxyapatite (HA) coatings were fabricated by a precipitation, sol-gel and dip-coating method. The effects of the aging time and the base used to adjust pH and substrate materials on the phases and microstructures of HA coatings were studied by field emission scanning electron microscopy FESEM, energy dispersive spectroscopy EDS, X-ray photoelectron spectroscopy XPS, and the vibrations of the phosphate groups were determined by Raman spectroscopy. The results showed that all the films were composed of the phases of TiO2 and HA. With coated titanium substrate with TiO2, the crystallinity of the HA coating increases, the structure became more compact and the Ca/P ratio increased because of the loss of P in the films. The addition of sodium hydroxide (adjusting the pH level to about 10) can increase the HA content in the coating. XPS and EDS results for steel substrate and titanium showed poor calcium content as obtained with a Ca/P ratio of 1.38 and 1.58, respectively, composition is similar to that of natural apatite. However, spectroscopic results suggest the presence of a mixture of hydroxyapatite and octacalcium phosphate. The different substrate materials have a high influence on the microstructure of the separated double films. However, hydroxyapatite nanopowders coatings were obtained using a simple method, with potential biomedical applications.

  4. Biological activity of lactoferrin-functionalized biomimetic hydroxyapatite nanocrystals

    PubMed Central

    Nocerino, Nunzia; Fulgione, Andrea; Iannaccone, Marco; Tomasetta, Laura; Ianniello, Flora; Martora, Francesca; Lelli, Marco; Roveri, Norberto; Capuano, Federico; Capparelli, Rosanna

    2014-01-01

    The emergence of bacterial strains resistant to antibiotics is a general public health problem. Progress in developing new molecules with antimicrobial properties has been made. In this study, we evaluated the biological activity of a hybrid nanocomposite composed of synthetic biomimetic hydroxyapatite surface-functionalized by lactoferrin (LF-HA). We evaluated the antimicrobial, anti-inflammatory, and antioxidant properties of LF-HA and found that the composite was active against both Gram-positive and Gram-negative bacteria, and that it modulated proinflammatory and anti-inflammatory responses and enhanced antioxidant properties as compared with LF alone. These results indicate the possibility of using LF-HA as an antimicrobial system and biomimetic hydroxyapatite as a candidate for innovative biomedical applications. PMID:24623976

  5. Hydroxyapatite synthesis using EDTA.

    PubMed

    Kang, Nak Heon; Kim, Soon Je; Song, Seung Han; Choi, Sang mun; Choi, Sik Young; Kim, Youn Jung

    2013-05-01

    Bone comprises structure of the body and consisted of inorganic substances. It exists in an organic structure in the body. Even though it is firm and has self-healing mechanism, it can be damaged by trauma, cancer, or bone diseases. Allograft can be an alternative solution for autologous bone graft. Hydroxyapatite (Ca10(PO4)6(OH)2), an excellent candidate for allograft, can be applied to bone defect area. There are several methods to produce hydroxyapatite; however, economical cost and being time consuming make the production difficult. In this study, we synthesized hydroxyapatite with EDTA. Freeze-dried bone allograft (Hans Biomed) was used as the control group. Synthesized hydroxyapatite was a rod-shaped, white powdery substance with 2- to 5-μm length and 0.5- to 1-μm width. X-ray diffraction showed the highest sharp peak at 32°C and high peaks at 25.8°C, 39.8°C, 46.8°C, 49.5°C, and 64.0°C, indicating a similar substance to the freeze-dried bone allograft. After 3 days, the cell growth of synthesized hydroxyapatite showed 1.5-fold more than did the bone allograft. Cellular and media alkaline phosphate activity increased similar to the bone allograft. In this study, we came up with a new method to produce the hydroxyapatite. It is a convenient method that can be held in room temperature and low pressure. Also, the product can be manufactured in large quantity. It can be also transformed into scaffold structure, which will perform a stronger configuration. The manufacturing method will help the bony defect patients and make future medical products.

  6. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    NASA Astrophysics Data System (ADS)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  7. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  8. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  9. Human osteoblast response to silicon-substituted hydroxyapatite.

    PubMed

    Botelho, C M; Brooks, R A; Best, S M; Lopes, M A; Santos, J D; Rushton, N; Bonfield, W

    2006-12-01

    Human osteoblasts were cultured on hydroxyapatite (HA), 0.8 wt % silicon substituted hydroxyapatite (Si-HA) and 1.5 wt % Si-HA discs. The influence of these substrates on cell behaviour in vitro was assessed by measuring total protein in the cell lysate and the production of several phenotypic markers: collagen type I (COL I), alkaline phosphatase (ALP), osteocalcin (OC), and the formation of bone mineral. After 7 days, beta-glycerophosphate and physiological levels of hydrocortisone were added to the culture medium to stimulate cell differentiation and mineral production. There was a significantly higher production of ALP on 1.5 wt % Si-HA at day 7 following which, the addition of hydrocortisone promoted the differentiation of cells on the other two substrates. Hydrocortisone addition also decreased the production of OC. During the period, when hydrocortisone was present, no significant difference in behavior was seen between cells on Si-HA and HA; however, following removal of hydrocortisone, cells responded to 0.8 wt % Si-HA with a significant increase in protein production. Using fluorescence microscopy, nodular structures labeled with tetracycline were observed on the surface of all substrates after 21 days. These structures were deposited on areas of high cell density but were not related to the presence or level of silicon in the substrate. These results indicate that human osteoblasts are affected by the presence of silicon in the HA substrate and that the timing of these effects may be dependent upon the level of silicon substitution.

  10. Compartmentalization in proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Brooke, S.; Fox, S. W.

    1977-01-01

    Proteinoid microspheres with stable internal compartments and internal structure are made from acidic proteinoid and basic proteinoid with calcium. The populations of microspheres are characterized by a wide diversity of structure. A model of primitive intracellular communication is suggested by the observed movement of internal particles between compartments of a multicompartmentalized unit. Differential response to pH change and to temperature change has been demonstrated within one population and suggests one mode of adaptive selection among primordial cell populations.

  11. Gel-derived bioglass as a compound of hydroxyapatite composites.

    PubMed

    Cholewa-Kowalska, Katarzyna; Kokoszka, Justyna; Laczka, Maria; Niedźwiedzki, Lukasz; Madej, Wojciech; Osyczka, Anna M

    2009-10-01

    Despite the excellent biocompatibility of hydroxyapatite and bioglass, their clinical applications are limited to non-load-bearing implants and implant coatings due to their low mechanical properties. We have developed two different composites made of hydroxyapatite (HA) and gel-derived bioglasses designated S2 (80 mol% SiO(2)-16 mol% CaO-4 mol% P(2)O(5)) or A2 (40 mol% SiO(2)-54 mol% CaO-6 mol% P(2)O(5)). We show that the combination of hydroxyapatite with either bioglass results in better composite bioactivity and biocompatibility compared to HA alone. We used a commercially available hydroxyapatite that was sintered with varying additions (10%, 50%) of A2 or S2 bioglass. Scanning electron microscopy and x-ray diffraction were used to characterize the microstructure and phases of the composites. The elastic properties of bioglass/HA composites were analyzed with the use of the pulse ultrasonic technique. The bioactivity (surface activity) of the composites was assessed by determining the changes of surface morphology and composition after soaking in simulated body fluid (SBF) for 7 and 14 days. The biocompatibility of the obtained composites was then assessed in vitro using adult human bone marrow stromal cells. Cells were seeded on the material surfaces at a density of 10(4) cells cm(-2) and cultured for 7 days in non-differentiating and osteogenic conditions. The number of live cells was estimated in both standard and osteogenic cultures, followed by alkaline phosphatase (ALP) activity assay in osteogenic cultures. We determined that 10 wt% addition of A2 (E = 12.24 GPa) and 50 wt% addition of S2 (E = 16.96 GPa) to the HA base results in higher Young's modulus of the composites compared to pure hydroxyapatite (E = 9.03 GPa). The rate of Ca-P rich layer formation is higher for bioglass/HA composites containing A2 bioglass compared to the composites containing S2 bioglass. Evaluation of cell growth on the bioglass/HA composites showed that the incorporation of

  12. The structural and biological properties of hydroxyapatite-modified titanate nanowire scaffolds.

    PubMed

    Zhao, Haixin; Dong, Wenjun; Zheng, Yingying; Liu, Aiping; Yao, Juming; Li, Chaorong; Tang, Weihua; Chen, Benyong; Wang, Ge; Shi, Zhan

    2011-09-01

    Hydroxyapatite-modified titanate nanowire scaffolds as alternative materials for tissue engineering have been developed via a titanate nanowire matrix assisted electrochemical deposition method. The macroporous titanate nanowire matrix on Ti metal was fabricated by a hydrothermal method, and then followed by an electrochemical synthesis of hydroxyapatite nanoparticles on titanate nanowire. The incorporation of titanate nanowire matrix with high oriented hydroxyapatite nanoparticles generates hierarchical scaffolds with highly osteogenic, structural integrity and excellent mechanical performance. As-prepared porous three dimensional interconnected hydroxyapatite-modified titanate nanowire scaffolds, mimicking the nature's extracellular matrix, could provide a suitable microenvironment for tissue cell ingrowth and differentiation. The ceramic titanate nanowire core with HA nanoparticle sheath structure displays superhydrophilicity, which facilitates the cell attachment and proliferation, and induces the in vitro tissue-engineered bone. Human osteoblast-like MG63 cells were cultured on the hydroxyapatite-modified titanate nanowire scaffolds, and the results showed that the scaffolds highly promote the bioactivity, osteoconductivity and osteoblast differentiation.

  13. Collagen hydrolysate based collagen/hydroxyapatite composite materials

    NASA Astrophysics Data System (ADS)

    Ficai, Anton; Albu, Madalina Georgiana; Birsan, Mihaela; Sonmez, Maria; Ficai, Denisa; Trandafir, Viorica; Andronescu, Ecaterina

    2013-04-01

    The aim of this study was to study the influence of collagen hydrolysate (HAS) on the formation of ternary collagen-hydrolysate/hydroxyapatite composite materials (COLL-HAS/HA). During the precipitation process of HA, a large amount of brushite is resulted at pH = 7 but, practically pure HA is obtained at pH ⩾ 8. The FTIR data reveal the duplication of the most important collagen absorption bands due to the presence of the collagen hydrolysate. The presence of collagen hydrolysate is beneficial for the management of bone and joint disorders such as osteoarthritis and osteoporosis.

  14. Hydroxyapatite-binding peptides for bone growth and inhibition

    DOEpatents

    Bertozzi, Carolyn R.; Song, Jie; Lee, Seung-Wuk

    2011-09-20

    Hydroxyapatite (HA)-binding peptides are selected using combinatorial phage library display. Pseudo-repetitive consensus amino acid sequences possessing periodic hydroxyl side chains in every two or three amino acid sequences are obtained. These sequences resemble the (Gly-Pro-Hyp).sub.x repeat of human type I collagen, a major component of extracellular matrices of natural bone. A consistent presence of basic amino acid residues is also observed. The peptides are synthesized by the solid-phase synthetic method and then used for template-driven HA-mineralization. Microscopy reveal that the peptides template the growth of polycrystalline HA crystals .about.40 nm in size.

  15. Preparation and characterization of PHBV microsphere/45S5 bioactive glass composite scaffolds with vancomycin releasing function.

    PubMed

    Li, Wei; Ding, Yaping; Rai, Ranjana; Roether, Judith A; Schubert, Dirk W; Boccaccini, Aldo R

    2014-08-01

    PHBV microsphere/45S5 bioactive glass (BG) composite scaffolds with drug release function were developed for bone tissue engineering. BG-based glass-ceramic scaffolds with high porosity (94%) and interconnected pore structure prepared by foam replication method were coated with PHBV microspheres (nominal diameter=3.5 μm) produced by water-in-oil-in-water double emulsion solvent evaporation method. A homogeneous microsphere coating throughout the porous structure of scaffolds was obtained by a simple dip coating method, using the slurry of PHBV microspheres in hexane. Compressive strength tests showed that the microsphere coating slightly improved the mechanical properties of the scaffolds. It was confirmed that the microsphere coating did not inhibit the bioactivity of the scaffolds in SBF. Hydroxyapatite crystals homogeneously grew not only on the struts of the scaffolds but also on the surface of microspheres within 7 days of immersion in SBF. Vancomycin was successfully encapsulated into the PHBV microspheres. The encapsulated vancomycin was released with a dual release profile involving a relatively low initial burst release (21%) and a sustained release (1 month), which is favorable compared to the high initial burst release (77%) and short release period (4 days) measured on uncoated scaffolds. The developed bioactive composite scaffold with drug delivery function has thus the potential to be used advantageously in bone tissue engineering.

  16. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  17. The influence of collagen support and ionic species on the morphology of collagen/hydroxyapatite composite materials

    SciTech Connect

    Ficai, Anton; Andronescu, Ecaterina; Voicu, Georgeta; Ghitulica, Cristina; Ficai, Denisa

    2010-04-15

    The purpose of this investigation is to study the influence of collagenous supports and ionic species on the precipitation of hydroxyapatite (HA) from aqueous solutions. To this end, we obtained hydroxyapatite by co-precipitation from a solution of calcium hydroxide and sodium dihydrogenophosphate. The formation of HA was studied by energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that the morphology of hydroxyapatite is highly influenced by the support material and the ionic species present. The obtained materials were studied by scanning electron microscopy (SEM).

  18. Nanocrystalline hydroxyapatite enriched in selenite and manganese ions: physicochemical and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Kolmas, Joanna; Groszyk, Ewa; Piotrowska, Urszula

    2015-07-01

    In this work, we used the co-precipitation method to synthesize hydroxyapatite (Mn-SeO3-HA) containing both selenium IV (approximately 3.60 wt.%) and manganese II (approximately 0.29 wt.%). Pure hydroxyapatite (HA), hydroxyapatite-containing manganese (II) ions (Mn-HA), and hydroxyapatite-containing selenite ions alone (SeO3-HA), prepared with the same method, were used as reference materials. The structures and physicochemical properties of all the obtained samples were investigated. PXRD studies showed that the obtained materials were homogeneous and consisted of apatite phase. Introducing selenites into the hydroxyapatite crystals considerably affects the size and degree of ordering. Experiments with transmission electron microscopy (TEM) showed that Mn-SeO3-HA crystals are very small, needle-like, and tend to form agglomerates. Fourier transform infrared spectroscopy (FT-IR) and solid-state nuclear magnetic resonance (ssNMR) were used to analyze the structure of the obtained material. Preliminary microbiological tests showed that the material demonstrated antibacterial activity against Staphylococcus aureus, yet such properties were not confirmed regarding Escherichia coli. PACS codes: 61, 76, 81

  19. Migration of Co-cultured Endothelial Cells and Osteoblasts in Composite Hydroxyapatite/Polylactic Acid Scaffolds

    DTIC Science & Technology

    2011-07-16

    Migration of Co-cultured Endothelial Cells and Osteoblasts in Composite Hydroxyapatite/ Polylactic Acid Scaffolds AMITA R. SHAH,1,2,3 SARITA R. SHAH,2...bone. A scaffold design consisting of a hydroxy apatite (HA) ring surrounding a polylactic acid (PLA) core simulates the structure of bone and provides...and osteoblasts in composite hydroxyapatite/ polylactic acid scaffolds. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR

  20. Influences of magnetized hydroxyapatite on the growth behaviors of osteoblasts and the mechanism from molecular dynamics simulation.

    PubMed

    Yang, Weihu; Xi, Xingfeng; Fang, Jiajia; Liu, Peng; Cai, Kaiyong

    2013-10-01

    To investigate the influence of magnetized hydroxyapatite on the growth and differentiation of osteoblasts, hydroxyapatite (HA) and magnetized hydroxyapatite (mHA) were synthesized and characterized. The cell viability, differentiation, and morphologies of osteoblasts were investigated in vitro, respectively. The results showed that compared to HA, cells cultured with mHA had better cell viability, and both HA and mHA were beneficial to the early differentiation of osteoblasts. Furthermore, the interaction mechanism between mHA and osteoblasts was elucidated using a molecular dynamics simulation. The simulation results indicated that when cultured with osteoblasts, HA adsorbed bovine serum protein onto its surface from the medium immediately, which was beneficial to the adhesion and proliferation of osteoblasts. The main driving force for the adsorption of bovine serum was the electronic properties of HA crystal faces. The (211) crystal face of HA had the highest electron density among its all crystal faces, thus mainly contributing to the protein adsorption of HA. Nevertheless, the (211) crystal face of mHA still had a relatively higher electron density than that of HA, thus possessing better protein adsorption than that of HA, and in turn promoting the biological functions of osteoblasts.

  1. Improved mechanical properties of hydroxyapatite whisker-reinforced poly(L-lactic acid) scaffold by surface modification of hydroxyapatite.

    PubMed

    Fang, Zhou; Feng, Qingling

    2014-02-01

    To improve the mechanical properties of porous hydroxyapatite/poly(L-lactic acid) (HA/PLLA) composites, HA whiskers with high crystallinity and high aspect ratio were synthesized. HA whiskers were modified with γ-aminopropyltriethoxysilane (APTES) to improve the interface between HA whiskers and PLLA. The composite scaffold consists of a porous PLLA matrix with HA whiskers distributed homogeneously. The morphology and the distributions of pore sizes of PLLA scaffold was not influenced by introducing HA whiskers, while the mechanical properties were improved. Both the compressive strength and compressive modulus were increased with the weight ratio of APTES-modified HA whiskers up to 30 wt.%, but only up to 15 wt.% for non-modified HA whiskers. With more than 15 wt.% HA whiskers, the mechanical properties of HA/PLLA scaffold were better improved with APTES-modified HA whiskers than non-modified. The HA whisker/PLLA scaffold with high porosity and improved mechanical properties is attractive in the application of tissue engineering.

  2. Hydroxyapatite Nanoparticles as a Novel Gene Carrier

    NASA Astrophysics Data System (ADS)

    Zhu, S. H.; Huang, B. Y.; Zhou, K. C.; Huang, S. P.; Liu, F.; Li, Y. M.; Xue, Z. G.; Long, Z. G.

    2004-06-01

    Hydroxyapatite crystalline nanoparticles were created by a precipitation hydrothermal technique and the majority of crystal particles were in the size range of 40-60nm and exhibited a colloidal feature when suspended in water. The gastric cancer SGC-7901 cell line cells were cultivated in the presence of10-100 μg ml-1 hydroxyapatite nanoparticle suspension and verified by MTT evaluation for their biocompatibility in vitro. The agarose gel electrophoresis analysis demonstrated that the HA nanoparticles potentially adsorb the green fluorescence protein EGFP-N1 plasmid DNA at pH 2 and 7, but not at pH 12. The DNA-nanoparticle complexes transfected EGFP-N1 pDNA into SGC-7901 cells in vitro with the efficiency about 80% as referenced with Lipofectmine TM 2000. In vivo animal experiment revealed no acute toxic adverse effect 2weeks after tail vein injection into mice, and TEM examination demonstrated their biodistribution and expression within the cytoplasm and also a little in the nuclei of the liver, kidney and brain tissue cells. These results suggest that the HA nanoparticle is a promising material that can be used as gene carrier, vectors.

  3. Silicate-doped hydroxyapatite and its promotive effect on bone mineralization

    NASA Astrophysics Data System (ADS)

    Qiu, Zhi-Ye; Noh, In-Sup; Zhang, Sheng-Min

    2013-03-01

    Bone defect is one of the most common diseases in clinic. Existing therapeutic approaches have encountered many problems, such as lack of autogenous allogeneic bone and immunological rejection to allogeneic implant. Synthetic hydroxyapatite (HA) provided solutions for bone repair, since the HA is the main inorganic component of animals' bone. However, HA has good biocompatibility, but does not possess osteogenic capability, which is of significance for modern bone repair materials. Si is an essential trace element in bone tissue, and it has been demonstrated to be able to promote bone formation. Therefore, silicate-doped hydroxyapatite (Si-HA) may serve as a promising material for bone repair, and promote bone regeneration in the repair. The current review discusses development of Si-HA, focusing on its preparation and characterization, in vitro and in vivo evaluations of the material, positive effect of Si-HA on promoting bone formation in clinical applications, and molecular mechanism investigation of such promotive effect.

  4. Controlled nucleation and growth of thin hydroxyapatite layers on titanium implants by using induction heating technique.

    PubMed

    Gómez Morales, J; Rodríguez Clemente, R; Armas, B; Combescure, C; Berjoan, R; Cubo, J; Martínez, E; García Carmona, J; Garelik, S; Murtra, J; Muraviev, D N

    2004-06-22

    This paper reports the results obtained by the development of a new wet method of hydroxyapatite (HA) thin layer deposition. The method is based on the localized precipitation of HA on metallic substrates activated by induction heating. The technique developed has been shown to allow for the complete coating of substrates with micrometric thin films of HA within a low processing time. The method has been successfully applied to coat Ti plaques and Ti-6A1-4V cylinders.

  5. [Hydroxyapatite bioactive coating on carbon/carbon composites].

    PubMed

    Sui, Jinling; Li, Musen; Lü, Yupeng; Bai, Yunqiang

    2005-04-01

    A simple plasma spraying method was employed in coating hydroxyapaptite (HA) on to carbon/carbon composites (C/C composites). The morphology of the coating was examined under scanning electron microscope (SEM). The phase constitutions of the HA coating were determined by X-ray diffractometer (XRD). The shear strength of the HA coating-C/C composite substrates was detected. A hydroxyapatite coating with rough surface was observed. A considerable amount of amorphous phase appeared as a result from the coating process, which could be transformed into the morphous phase crystalline HA after subsequent heat treatment. The shear strength between the HA coating and C/C composite substrates was 7.15 MPa.

  6. Nanocrystalline Hydroxyapatite/Si Coating by Mechanical Alloying Technique

    PubMed Central

    Hannora, Ahmed E.; Mukasyan, Alexander S.; Mansurov, Zulkhair A.

    2012-01-01

    A novel approach for depositing hydroxyapatite (HA) films on titanium substrates by using mechanical alloying (MA) technique has been developed. However, it was shown that one-hour heat treatment at 800°C of such mechanically coated HA layer leads to partial transformation of desired HA phase to beta-tri-calcium phosphate (β-TCP) phase. It appears that the grain boundary and interface defects formed during MA promote this transformation. It was discovered that doping HA by silicon results in hindering this phase transformation process. The Si-doped HA does not show phase transition to β-TCP or decomposition after heat treatment even at 900°C. PMID:22312324

  7. Effect of n-HA with different surface-modified on the properties of n-HA/PLGA composite

    NASA Astrophysics Data System (ADS)

    Liuyun, Jiang; Chengdong, Xiong; Dongliang, Chen; Lixin, Jiang; xiubing, Pang

    2012-10-01

    Three different surface modification methods for nano-hydroxyapatite (n-HA) of stearic acid, grafted with L-lactide, combining stearic acid and surface-grafting L-lactic were adopted, respectively. The surface modification reaction and the effect of different methods were evaluated by Fourier transformation infrared (FTIR), X-ray photoelectron spectra (XPS), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM). The results showed that n-HA surfaces were all successful modified, and the modification method of combining stearic acid and surface-grafting L-lactic had the greatest grafting amount and the best dispersion among the three modification methods. Then, the n-HA with three different surface modification and unmodified n-HA were introduced into PLGA, respectively, and a serials of n-HA/PLGA composites with 3% n-HA amount in weight were prepared by solution mixing, and the properties of n-HA/PLGA composites were also investigated by electromechanical universal tester and scanning electron microscope(SEM), comparing with PLGA. The results showed that the n-HA/PLGA composite with the n-HA surface modified by combining stearic acid and surface-grafting L-lactic had the highest bending strength and the best dispersion and interfacial adhesion among the three different modification methods, suggesting the surface modification of combining stearic acid and surface-grafting L-lactic was the most ideal method in this study, which has a great deal of enhancement of bending strength than PLGA, and it would be potential to be used in the field of bone fracture internal fixation in future.

  8. Hydroxyapatite Deposition Disease

    DTIC Science & Technology

    2006-11-01

    calcific tendinitis or calcific periarthritis, is characterized by the deposition of calcium phosphate crystals (predominantly hydroxyapatite) in...site of HADD is the hip, where calcifications are usually found in the gluteus medius tendon or along the femur at various sites of tendinous ...posterolateral femoral diaphysis, as well as in various other tendinous attachments to the femur. Computed tomography is also helpful in the demonstration

  9. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  10. Sonochemical IN SITU Synthesis of Hydroxyapatite in Hdpe and PMMA

    NASA Astrophysics Data System (ADS)

    Cristina, Parra; Gema, González; Carmen, Albano

    2008-08-01

    In the present work, characterization of composite materials based on HDPE and PMMA filled with nanometric hydroxyapatite synthesized in situ by high frequency ultrasound has been carried out. For the composites preparation dilutions of the commercial polymers, using decaline as solvent for the HDPE and 2-butanone for PMMA, were employed. For the synthesis of Hydroxyapatite (HA), ammonium phosphate [(NH4)2HPO4] and calcium hydroxide [Ca(OH)2] were used as precursors. The products obtained were characterized by FTIR and TEM. The results showed that when PMMA was used as matrix, the presence of nanometric HA with clear interactions with the PMMA matrix was obtained. When HDPE was used as matrix a complex complex calcium phase was obtained and without interaction with the matrix.

  11. Synthesis of sodium caseinate-calcium carbonate microspheres and their mineralization to bone-like apatite

    NASA Astrophysics Data System (ADS)

    Xu, Zhewu; Liang, Guobin; Jin, Lin; Wang, Zhenling; Xing, Chao; Jiange, Qing; Zhang, Zhiguang

    2014-06-01

    Phosphoproteins can induce and stabilize calcium carbonate (CaCO3) vaterite, which has desirable features for high reactivity. The purpose of this study was to synthesize bioactive CaCO3 microspheres for bone regeneration. Sodium caseinate (NaCas)-containing CaCO3 microspheres, with the crystal phase of vaterite, were synthesized by fast precipitation in an aqueous solution of CaCl2, Na2CO3, and 2 mg/mL of NaCas. The uniform microspheres exhibited rougher surfaces and lower negative charges than CaCO3 particles without NaCas addition. Fourier-transform infrared spectroscopy (FT-IR) of the microspheres showed characteristic peaks or bands corresponding to phosphate and hydroxyl groups. Thermogravimetric analysis (TGA) curves exhibited approximately 5% weight loss below 600 °C due to the decomposition of NaCas. Scanning electron microscope (SEM) images showed lath-like hydroxyapatite (HAp) on the surface after soaking in simulated body fluid (SBF) at 37 °C for 5 and 10 days. Energy dispersive X-ray spectrometry (EDS) revealed that the agglomerates were composed of Ca, C, O, P, Na, and Mg elements, and the Ca/P ratios ranged from 1.53 to 1.56. X-ray diffraction (XRD) patterns exhibited peaks characteristic of hydroxyapatite. The results of this study demonstrated that the addition of NaCas induced the formation of vaterite microspheres which possesses an enhanced apatite formation after soaking in SBF at 37 °C for 5 and 10 days. These NaCas-CaCO3 microspheres may be a potential biomaterial for bone regeneration.

  12. Preparation and Characterization of 45S5 Bioactive Glass-based Scaffolds Loaded with PHBV Microspheres with Daidzein Release Function.

    PubMed

    Macías-Andrés, Víctor I; Li, Wei; Aguilar-Reyes, Ena A; Ding, Yaping; Roether, Judith A; Harhaus, Leila; León-Patiño, Carlos A; Boccaccini, A R

    2017-02-27

    PHBV microsphere loaded 45S5 bioactive glass (BG) based scaffolds with drug releasing capability have been developed. PHBV microspheres with a mean particle size 4 ± 2 μm loaded with daidzein were obtained by oil-in-water single emulsion solvent evaporation method and applied to the surface of BG scaffolds by dip coating technique. The morphology, in vitro bioactivity in simulated body fluid (SBF), mechanical properties and drug release kinetics of microsphere loaded scaffolds were studied. The microspheres were shown to be homogeneously dispersed on the scaffold surfaces. It was confirmed that hydroxyapatite crystals homogeneously grew not only on the surface of the scaffold but also on the surface of the microspheres within 3 days of immersion in SBF. The daidzein release from the microsphere loaded scaffolds lasted almost 1 month and was determined to be diffusion controlled. The microsphere loaded BG scaffolds with daidzein releasing capability obtained in this study are a candidate for bone tissue engineering. This article is protected by copyright. All rights reserved.

  13. Immobilization of RGD peptide on HA coating through a chemical bonding approach.

    PubMed

    Yang, Chunli; Cheng, Kui; Weng, Wenjian; Yang, Chunyu

    2009-11-01

    In this work, Arg-Gly-Asp (RGD) sequence containing peptide was immobilized on hydroxyapatite (HA) coatings through a chemical bonding approach in two steps, surface modification with 3-aminopropyltriethoxysilane (APTES) and RGD immobilization. The results indicate that RGD has been successfully immobilized on HA coatings. Comparing with physical adsorption coatings, the chemically bonded RGD on the coatings shows much better anti-wash-out ability. Since RGD is able to recognize cell-membrane integrins on biointerfaces, the present method will be an effective way to favor interaction of cells with HA coatings.

  14. Dual functional selenium-substituted hydroxyapatite

    PubMed Central

    Wang, Yanhua; Ma, Jun; Zhou, Lei; Chen, Jin; Liu, Yonghui; Qiu, Zhiye; Zhang, Shengmin

    2012-01-01

    Hydroxyapatite (HA) doped with trace elements has attracted much attention recently owing to its excellent biological functions. Herein, we use a facile co-precipitation method to incorporate selenium into HA by adding sodium selenite during synthesis. The obtained selenium-substituted HA products are needle-like nanoparticles which have  size and crystallinity that are similar to those of the pure HA nanoparticles (HANs) when the selenium content is low. HANs are found to have the ability to induce the apoptosis of osteosarcoma cells, and the anti-tumour effects are enhanced after incorporation of selenium. Meanwhile, the nanoparticles can also support the growth of bone marrow stem cells. Furthermore, the flow cytometric results indicate that the apoptosis induction of osteosarcoma cells is caused by the increased reactive oxygen species and decreased mitochondrial membrane potential. These results show that the selenium-substituted HANs are potentially promising bone graft materials in osteosarcoma treatment due to their dual functions of supporting normal cell growth and inducing tumour cell apoptosis. PMID:23741613

  15. Long-term biocompatibility evaluation of 0.5 % zinc containing hydroxyapatite in rabbits.

    PubMed

    Resende, Rodrigo F B; Fernandes, Gustavo V O; Santos, Sílvia R A; Rossi, Alexandre M; Lima, Inayá; Granjeiro, José M; Calasans-Maia, Mônica D

    2013-06-01

    This study investigates the long-term biocompatibility of 0.5 % zinc-containing hydroxyapatite compared with hydroxyapatite. Spheres (425 < ∅ < 550) of both materials were produced by extrusion of ceramic slurry in calcium chloride and characterized by FTIR, XRD, XRF and SEM. Fifteen White New Zealand rabbits were submitted to general anesthesia, and an perforation (2 mm), was made in each tibia, one for zinc-containing hydroxyapatite sphere implantation and one for hydroxyapatite sphere implantation. After 26, 52 and 78 weeks, the animals were euthanized, and the fragment containing the biomaterial was harvested. A 30-50 μm section was obtained for histological analysis in bright field and polarized light. SEM images revealed similar morphologies between the tested biomaterials. Histological analysis showed that there was no difference between the test groups. The morphometric analysis, however, indicates that there was a greater absorption. The materials are biocompatible, promote osteogenesis and that the zinc-containing hydroxyapatite microspheres were absorbed more quickly.

  16. Doped zinc oxide microspheres

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  17. Microsphere insulation systems

    NASA Technical Reports Server (NTRS)

    Allen, Mark S. (Inventor); Willen, Gary S. (Inventor); Mohling, Robert A. (Inventor)

    2005-01-01

    A new insulation system is provided that contains microspheres. This insulation system can be used to provide insulated panels and clamshells, and to insulate annular spaces around objects used to transfer, store, or transport cryogens and other temperature-sensitive materials. This insulation system provides better performance with reduced maintenance than current insulation systems.

  18. Doped zinc oxide microspheres

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  19. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1979-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  20. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  1. Effect of Hydrothermal Treatment on Sinterability of Hydroxyapatite

    SciTech Connect

    Kawagoe, D.; Fujimori, H.; Goto, S.; Yamasaki, N.; Ioku, K.

    2006-05-15

    Calcium hydroxyapatite, Ca10(PO4)6(OH)2:HA, is the inorganic principle component of natural bones and teeth. It has been already suggested that the amount of OH ion in the crystal structure of HA is closely related to the biocompatibility. The amount of OH ion in current HA, however, has not been controlled. In order to prepare more functional HA ceramics, the amount of OH ion must be controlled. In this study, HA ceramics with different OH amount were prepared from fine HA crystals by spark plasma sintering (SPS). Fine powder of HA was treated hydrothermally at 200 deg. C for 24 h with pH 10 NH3 aqueous solution. The samples were pressed uniaxialy under 60 MPa, and then they were SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min with the heating rate of 25 deg. C{center_dot}min-1. No phases other than HA were revealed by XRD for the starting samples after hydrothermal treatment and samples after sintering by SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min. The quantity of OH ion in HA ceramics sintered by SPS was decreased with increasing temperature of sintering. Transparent HA ceramics were prepared by SPS at 900 deg. C and 1000 deg. C.

  2. Concentrated hydroxyapatite inks for direct-write assembly of 3-D periodic scaffolds.

    PubMed

    Michna, Sarah; Wu, Willie; Lewis, Jennifer A

    2005-10-01

    Hydroxyapatite (HA) scaffolds with a 3-D periodic architecture and multiscale porosity have been fabricated by direct-write assembly. Concentrated HA inks with tailored viscoelastic properties were developed to enable the construction of complex 3-D architectures comprised of self-supporting cylindrical rods in a layer-by-layer patterning sequence. By controlling their lattice constant and sintering conditions, 3-D periodic HA scaffolds were produced with a bimodal pore size distribution. Mercury intrusion porosimetry (MIP) was used to determine the characteristic pore size and volume associated with the interconnected pore channels between HA rods and the finer pores within the partially sintered HA rods.

  3. Effect of Water-Glass Coating on HA and HA-TCP Samples for MSCs Adhesion, Proliferation, and Differentiation

    PubMed Central

    Bajpai, Indu; Kim, Duk Yeon; Kyong-Jin, Jung; Song, In-Hwan

    2016-01-01

    Ca-P and silicon based materials have become very popular as bone tissue engineering materials. In this study, water-glass (also known as sodium silicate glass) was coated on sintered hydroxyapatite (HA) and HA-TCP (TCP stands for tricalcium phosphate) samples and subsequently heat-treated at 600°C for 2 hrs. X-rays diffraction showed the presence of β- and α-TCP phases along with HA in the HA-TCP samples. Samples without coating, with water-glass coating, and heat-treated after water-glass coating were used to observe the adhesion and proliferation response of bone marrow derived-mesenchymal stem cells (MSCs). Cell culture was carried out for 4 hrs, 1 day, and 7 days. Interestingly, all samples showed similar response for cell adhesion and proliferation up to 7-day culture but fibronectin, E-cadherin, and osteogenic differentiation related genes (osteocalcin and osteopontin) were significantly induced in heat-treated water-glass coated HA-TCP samples. A water-glass coating on Ca-P samples was not found to influence the cell proliferation response significantly but activated some extracellular matrix genes and induced osteogenic differentiation in the MSCs. PMID:27429988

  4. Towards optimization of the silanization process of hydroxyapatite for its use in bone cement formulations.

    PubMed

    Cisneros-Pineda, Olga G; Herrera Kao, Wilberth; Loría-Bastarrachea, María I; Veranes-Pantoja, Yaymarilis; Cauich-Rodríguez, Juan V; Cervantes-Uc, José M

    2014-07-01

    The aim of this work was to provide some fundamental information for optimization of silanization of hydroxyapatite intended for bone cement formulations. The effect of 3-(trimethoxysilyl) propyl methacrylate (MPS) concentration and solvent system (acetone/water or methanol/water mixtures) during HA silanization was monitored by X-ray diffraction (XRD), FTIR spectroscopy and EDX analysis. The effect of silanized HA on the mechanical properties of acrylic bone cements is also reported. It was found that the silanization process rendered hydroxyapatite with lower crystallinity compared to untreated HA. Through EDX, it was observed that the silicon concentration in the HA particles was higher for acetone-water than that obtained for methanol-water system, although the mechanical performance of cements prepared with these particles exhibited the opposite behavior. Taking all these results together, it is concluded that methanol-water system containing MPS at 3wt.% provides the better results during silanization process of HA.

  5. Synthesis of dense nano cobalt-hydroxyapatite by modified electroless deposition technique

    NASA Astrophysics Data System (ADS)

    Mohd Zaheruddin, K.; Rahmat, A.; Shamsul, J. B.; Mohd Nazree, B. D.; Aimi Noorliyana, H.

    2016-07-01

    Cobalt-hydroxyapatite (Co-HA) composites was successfully prepared by simple electroless deposition process of Co on the surface of hydroxyapatite (HA) particles. Co deposition was carried out in an alkaline bath with sodium hypophosphite as a reducing agent. The electroless process was carried out without sensitization and activation steps. The deposition of Co onto HA was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The Co-HA composite powder was compacted and sintered at 1250°C. The Co particles were homogeneously dispersed in the HA matrix after sintering and the mechanical properties of composites was enhanced to 100 % with 3 % wt Co and gradually decreased at higher Co content.

  6. Pyroelectric, piezoelectric, and photoeffects in hydroxyapatite thin films on silicon

    NASA Astrophysics Data System (ADS)

    Lang, S. B.; Tofail, S. A. M.; Gandhi, A. A.; Gregor, M.; Wolf-Brandstetter, C.; Kost, J.; Bauer, S.; Krause, M.

    2011-03-01

    Hydroxyapatite (HA) is the major component of bone and is used in artificial form in many biomedical applications. It was once believed to have a centrosymmetric crystal structure. In theoretical and experimental studies published in 2005, it was shown to have a monoclinic P21 structure. In the work reported here, 500 nm films of HA were spin-coated on silicon wafers. The materials were not poled. They had a nonuniform polarization distribution and exhibited pyroelectricity, piezoelectricity, and photoeffects. Structures of this type may have a number of technological applications.

  7. Thermal and optical characterization of the calcium phosphate biomaterial hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Bento, A. C.; Almond, D. P.; Brown, S. R.; Turner, I. G.

    1996-05-01

    Thermal wave interferometry (TWI) has been used to measure the thermophysical properties of hydroxyapatite (HA) coatings, prepared by the plasma-spraying process on titanium alloy substrates. The properties measured were thermal diffusivity, thermal conductivity, thermal effusivity, and volumetric heat capacity and the optical absorption coefficient. The thermal conductivity obtained was found to be of similar magnitude to that of human tooth enamel. The results presented confirm the usefulness of TWI as a nondestructive technique for the characterization of plasma-sprayed HA coatings.

  8. The Efficacy of Hydroxyapatite for Screw Augmentation in Osteoporotic Patients

    PubMed Central

    Jang, Sang Hoon; Lee, June Ho; Cho, Ji Young; Lee, Ho-Yeon; Lee, Sang-Ho

    2013-01-01

    The stability of screw constructs is of considerable importance in determining the outcome, especially in spinal osteoporosis. Polymethylmethacrylate (PMMA) has been proven as an effective material for increasing the pullout strength of pedicle screws inserted into the osteoporotic bones. However, PMMA has several disadvantages, such as its exothermic properties, the risk of neural injury in the event of extravasation, and difficulties in performing revision surgery. In the current study, we used hydroxyapatite (HA) cement for screw augmentation in spinal osteoporosis. We conclude that HA cement is a useful tool for screw augmentation and recommend it as a promising option for spinal instrumentation in osteoporotic patients. PMID:24201099

  9. Degradation behavior and compatibility of micro, nanoHA/chitosan scaffolds with interconnected spherical macropores.

    PubMed

    Ruixin, Li; Cheng, Xu; Yingjie, Liu; Hao, Li; Caihong, Shi; Weihua, Su; Weining, An; Yinghai, Yuan; Xiaoli, Qin; Yunqiang, Xu; Xizheng, Zhang; Hui, Li

    2017-03-30

    Hydroxyapatite/Chitosan (HA/CS) composite have significant application in biomedical especially for bone replacement. Inorganic particle shape and size of composite affect the scaffold mechanical property, biological property, and degradation. The aim of this study was to fabricate HA/CS scaffold with good pore connectivity and analyze their biological, degradation properties. Microhydroxyapatite/chitosan(mHA/CS) and nanohydroxyapatite/chitosan (nHA/CS) composite scaffolds with interconnected spherical pore architectures were fabricated. Composite scaffolds structure parameters were analyzed using micro CT. Cell proliferation and morphology were tested and compared between two scaffolds using mouse osteoblastic cell line MC3T3-E1. To research the composite degradation in lysozyme PBS solution, degradation rate and reducing sugar content were tested, and scaffolds morphology were observed by SEM. The results showed that microHA and nanoHA were fabricated by being calcined and synthesis methods, and their infrared spectra are very similar. EDAX composition analysis demonstrated that both of microHA and nanoHA were calcium deficiency HA. Micro-CT results demonstrated the scaffolds had interconnected spherical pores, and the structure parameters were similar. Cell viabilities were significant increased with cultured time, but there were no significant difference between microHA/CS and nanoHA/CS scaffolds. Scaffold structure was gradually destroyed and inorganic composition HA particles are more prominent with degradation time.

  10. Effect of nano-hydroxyapatite concentration on remineralization of initial enamel lesion in vitro.

    PubMed

    Huang, S B; Gao, S S; Yu, H Y

    2009-06-01

    The purpose of the research was to determine the effect of nano-hydroxyapatite concentrations on initial enamel lesions under dynamic pH-cycling conditions. Initial enamel lesions were prepared in bovine enamel with an acidic buffer. NaF (positive control), deionized water (negative control) and four different concentrations of nano-hydroxyapatite (1%, 5%, 10% and 15% wt%) were selected as the treatment agents. Surface microhardness (SMH) measurements were performed before/after demineralization and after 3, 6, 9 and 12 days of application, and the percentage surface microhardness recovery (%SMHR) was calculated. The specimens were then examined by a scanning electron microscope. The %SMHR in nano-hydroxyapatite groups was significantly greater than that of negative control. When the concentration of nano-HA was under 10%, SMH and %SMHR increased with increasing nano-hydroxyapatite concentrations. There were no significant differences between the 10% and 15% groups at different time periods in the pH-cycling. The SEM analysis showed that nano-hydroxyapatite particles were regularly deposited on the cellular structure of the demineralized enamel surface, which appeared to form new surface layers. It was concluded that nano-hydroxyapatite had the potential to remineralize initial enamel lesions. A concentration of 10% nano-hydroxyapatite may be optimal for remineralization of early enamel caries.

  11. Porous microsphere and its applications

    PubMed Central

    Cai, Yunpeng; Chen, Yinghui; Hong, Xiaoyun; Liu, Zhenguo; Yuan, Weien

    2013-01-01

    Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies. PMID:23515359

  12. Post-translational modification of osteopontin: Effects on in vitro hydroxyapatite formation and growth

    SciTech Connect

    Boskey, Adele L.; Christensen, Brian; Taleb, Hayat; Sorensen, Esben S.

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer Thrombin-cleaved fragments of milk-osteopontin effect hydroxyapatite formation differently. Black-Right-Pointing-Pointer N- and C-terminal fragments promoted hydroxyapatite formation and growth. Black-Right-Pointing-Pointer A central fragment inhibited hydroxyapatite formation and growth. Black-Right-Pointing-Pointer Binding to collagen or hydroxyapatite seed crystals modified these effects. -- Abstract: The manuscript tests the hypothesis that posttranslational modification of the SIBLING family of proteins in general and osteopontin in particular modify the abilities of these proteins to regulate in vitro hydroxyapatite (HA) formation. Osteopontin has diverse effects on hydroxyapatite (HA) mineral crystallite formation and growth depending on the extent of phosphorylation. We hypothesized that different regions of full-length OPN would also have distinct effects on the mineralization process. Thrombin fragmentation of milk OPN (mOPN) was used to test this hypothesis. Three fragments were tested in a de novo HA formation assay; an N-terminal fragment (aa 1-147), a central fragment (aa 148-204) denoted SKK-fragment and a C-terminal fragment (aa 205-262). Compared to intact mOPN the C- and N-terminal fragments behaved comparably, promoting HA formation and growth, but the central SKK-fragment acted as a mineralization inhibitor. In a seeded growth experiment all fragments inhibited mineral proliferation, but the SKK-fragment was the most effective inhibitor. These effects, seen in HA-formation and seeded growth assays in a gelatin gel system and in a pH-stat experiment were lost when the protein or fragments were dephosphorylated. Effects of the fully phosphorylated protein and fragments were also altered in the presence of fibrillar collagen. The diverse effects can be explained in terms of the intrinsically disordered nature of OPN and its fragments which enable them to interact with their multiple partners.

  13. Bio resorbability of the modified hydroxyapatite in Tris-HCL buffer

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.

    2016-02-01

    The solubility of carbonated hydroxyapatite powders and granulated carbonated hydroxyapatite produced from the synovial biofluid model solution has been studied. The kinetic characteristics of dissolution were determined. It was found that the solubility of carbonated hydroxyapatite is higher as compared to that of hydroxyapatite. The impact of the organic matrix on the rate of sample dissolution was revealed. For HA-gelatin composites, as the gelatin concentration grows, the dissolution rate becomes greater, and a sample of 6.0 g / L concentration has higher resorbability. The results of the research can be used to study the kinetics of dissolution and the biocompatibility of ceramic materials for medicine, namely for reconstructive surgery, dentistry, and development of drug delivery systems.

  14. Cytotoxicity and genotoxicity property of hydroxyapatite-mullite eluates.

    PubMed

    Kalmodia, Sushma; Sharma, Vyom; Pandey, Alok K; Dhawan, Alok; Basu, Bikramjit

    2011-02-01

    Long-term biomedical applications of implant materials may cause osteolysis, aseptic losing and toxicity. Therefore, we investigated the cytotoxic and genotoxic potential of hydroxyapatite (HA) mullite eluates in L929 mouse fibroblast cells. The spark plasma sintered HA-20% mullite biocomposite (HA20M) were ground using mortar and pestle as well as ball milling. The cells were exposed for 6 h to varying concentrations (10, 25, 50, 75 and 100%) of the eluates of HA-20% mullite (87 nm), HA (171 nm) and mullite (154 nm). The scanning electron microscopy and MTT assay revealed the concentration dependent toxicity of H20M eluate at and above 50%. The analysis of the DNA damaging potential of HA, mullite and HA20M eluates using Comet assay demonstrated a significant DNA damage by HA20M which was largely related to the presence of mullite. The results collectively demonstrate the cytotoxic and genotoxic potential of HA20M eluate in L929 cells is dependent on particle size, concentration and composition.

  15. Synthesis and characterization of wool keratin/hydroxyapatite nanocomposite.

    PubMed

    Li, Jiashen; Liu, Xuan; Zhang, Jing; Zhang, Yu; Han, Yanxia; Hu, Junyan; Li, Yi

    2012-05-01

    Taking the inspiration from the biomineral, the wool keratin was selected to modulate the assembly of nanosized hydroxyapatite (HA) crystals via a coprecipitation method. A series of keratin/HA nanocomposite with different ratios were synthesized by adjusting the concentrations of keratin solutions and calcium phosphate and their final components were detected by thermogravimetric analysis (TGA). The transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed that keratin in the composite decreased the crystallinity of HA. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to examine the chemical and surface structure of the composites. In vitro biocompatibility results revealed that cells showed better viability on keratin/HA composites which have a ratio of organics and inorganics similar to that of natural bones.

  16. Toughening mechanisms in iron-containing hydroxyapatite/titanium composites.

    PubMed

    Chang, Q; Chen, D L; Ru, H Q; Yue, X Y; Yu, L; Zhang, C P

    2010-03-01

    Pure hydroxyapatite (HA) is brittle and it cannot be directly used for the load-bearing biomedical applications. The purpose of this investigation was to develop a new iron-containing HA/titanium composite via pressureless sintering at a relatively low temperature with particular emphasis on identifying the underlying toughening mechanisms. The addition of iron to HA/titanium composites led to a unique and favorable core/shell microstructure of Ti-Fe particles that consisted of outer titanium and inner iron, and good interfacial bonding with HA matrix. While the relative density, hardness and Young's modulus reduced, the flexural strength, fracture toughness, fatigue resistance, and the related fracture surface roughness increased significantly with increasing amount of Ti-Fe particles. Different toughening mechanisms including crack bridging, branching and deflection were observed in the composites, thus effectively increasing the crack propagation resistance and resulting in a substantial improvement in the mechanical properties of the composites.

  17. Biological reactivity of zirconia-hydroxyapatite composites.

    PubMed

    Silva, Viviane V; Lameiras, Fernando S; Lobato, Zélia I P

    2002-01-01

    Materials and devices intended for end-use applications as implants and medical devices must be evaluated to determine their biocompatibility potential in contact with physiological systems. The use of standard practices of biological testing provides a reasonable level of confidence concerning the response of a living organism to a given material or device, as well as guidance in selecting the proper procedures to be carried out for the screening of new or modified materials. This article presents results from cytotoxicity assays of cell culture, skin irritation, and acute toxicity by systemic and intracutaneous injections for powders, ceramic bodies, and extract liquids of hydroxyapatite (HA), calcia partially stabilized zirconia (ZO), and two types of zirconia-hydroxyapatite composites (Z4H6 and Z6H4) with potential for future use as orthopedic and dental implants. They indicate that these materials present potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity of ATCC cell cultures (CCL1 NCTC clone 929 of mouse connective tissue and CCL 81 of monkey connective tissue) and animals (rabbit and mouse) with direct or indirect patient contact, or by the injection of specific extracts prepared from the material under test. In addition, studies involving short-term intramuscular and long-term implantation assays to estimate the reaction of living tissue to the composites studied, and investigations on long-term effects that these materials can cause on the cellular metabolism, are already in progress.

  18. Antimicrobial and osteogenic properties of a hydrophilic-modified nanoscale hydroxyapatite coating on titanium.

    PubMed

    Murakami, Asuka; Arimoto, Takafumi; Suzuki, Dai; Iwai-Yoshida, Misato; Otsuka, Fukunaga; Shibata, Yo; Igarashi, Takeshi; Kamijo, Ryutaro; Miyazaki, Takashi

    2012-04-01

    Hydroxyapatite (HA)-coated titanium (Ti) is commonly used for implantable medical devices. This study examined in vitro osteoblast gene expression and antimicrobial activity against early and late colonizers of supra-gingival plaque on nanoscale HA-coated Ti prepared by discharge in a physiological buffered solution. The HA-coated Ti surface showed super-hydrophilicity, whereas the densely sintered HA and Ti surfaces alone showed lower hydrophilicity. The sintered HA and HA-coated Ti surfaces enhanced osteoblast phenotypes in comparison with the bare Ti surface. The HA-coated Ti enabled antimicrobial activity against early colonizers of supra-gingival plaques, namely Streptococcus mitis and Streptococcus gordonii. Such antimicrobial activity may be caused by the surface hydrophilicity, thereby leading to a repulsion force between the HA-coated Ti surface and the bacterial cell membranes. On the contrary, the sintered HA sample was susceptible to infection of microorganisms. Thus, hydrophilic-modified HA-coated Ti may have potential for use in implantable medical devices. From the Clinical Editor: This study establishes that Hydroxyapatite (HA)-coated titanium (Ti) surface of implanted devices may result in an optimal microenvironment to control and prevent infections and may have potential future clinical applications.

  19. Strontium-substituted hydroxyapatite coatings deposited via a co-deposition sputter technique.

    PubMed

    Boyd, A R; Rutledge, L; Randolph, L D; Meenan, B J

    2015-01-01

    The bioactivity of hydroxyapatite (HA) coatings can be modified by the addition of different ions, such as silicon (Si), lithium (Li), magnesium (Mg), zinc (Zn) or strontium (Sr) into the HA lattice. Of the ions listed here, strontium substituted hydroxyapatite (SrHA) coatings have received a lot of interest recently as Sr has been shown to promote osteoblast proliferation and differentiation, and reduce osteoclast activity. In this study, SrHA coatings were deposited onto titanium substrates using radio frequency (RF) magnetron co-sputtering (and compared to those surfaces deposited from HA alone). FTIR, XPS, XRD, and SEM techniques were used to analyse the different coatings produced, whereby different combinations of pure HA and 13% Sr-substituted HA targets were investigated. The results highlight that Sr could be successfully incorporated into the HA lattice to form SrHA coatings. It was observed that as the number of SrHA sputtering targets in the study were increased (increasing Sr content), the deposition rate decreased. It was also shown that as the Sr content of the coatings increased, so did the degree of preferred 002 orientation of the coating (along with obvious changes in the surface morphology). This study has shown that RF magnetron sputtering (specifically co-sputtering), offers an appropriate methodology to control the surface properties of Sr-substituted HA, such as the crystallinity, stoichiometry, phase purity and surface morphology.

  20. Molecular dynamics simulations on the interaction between polymers and hydroxyapatite with and without coupling agents.

    PubMed

    Zhang, Hong-ping; Lu, Xiong; Leng, Yang; Fang, Liming; Qu, Shuxin; Feng, Bo; Weng, Jie; Wang, Jianxin

    2009-05-01

    Molecular dynamics (MD) simulations were employed to study hydroxyapatite/biopolymer interface interactions in composites for biomedical applications. The study analyzed the binding energies between hydroxyapatite (HA) and three polymers: polyethylene (PE), polyamide (PA) and polylactic acid (PLA). The interactions of polymers on HA crystallographic planes (001), (100) and (110) were simulated. The effects of the silane coupling agent (A174) on interfacial binding energies were also examined. The results show that HA (110) has the highest binding energy with these polymers because of its higher planar atom density than that of HA (001) and (100). The binding energies of PA/HA and PLA/HA are much higher than that of PE/HA, which might be attributed to large number of polar groups in PA and PLA chains. The silane coupling agent A174 increases the binding energy between PE and HA, but not for the PA/HA and PLA/HA systems. The MD results can be used to guide the design of polymer/HA composites and to select proper coupling agents.

  1. Functional magnetic microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  2. Comparison of murine fibroblast cell response to fluor-hydroxyapatite composite, fluorapatite and hydroxyapatite by eluate assay.

    PubMed

    Jantová, Sona; Letasiová, Silvia; Theiszová, Marica; Palou, M

    2009-03-01

    Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetic composite that contains the same molecular concentration of OH(-) groups and F(-) ions. The aim of this experiment was to evaluate the cellular responses of murine fibroblast NIH-3T3 cells in vitro to solid solutions of FHA and FA and to compare them with the effect of hydroxyapatite (HA). We studied 24, 48 and 72 h effects of biomaterials on cell morphology, proliferation and cell cycle of NIH-3T3 cells by eluate assay. Furthermore, we examined the ability of FHA, FA and HA to induce cell death and DNA damage. Our cytotoxic/antiproliferative studies indicated that any of tested biomaterials did not cause the total inhibition of cell division. Biomaterials induced different antiproliferative effects increasing in the order HA < FHA < FA which were time- and concentration-dependent. None of the tested biomaterials induced necrotic/apoptotic death of NIH-3T3 cells. On the other hand, after 72 h we found that FHA and FA induced G0/G1 arrest of NIH-3T3 cells, while HA did not affect any cell cycle phases. Comet assay showed that while HA demonstrated weaker genotoxicity, DNA damage induced by FHA and FA caused G0/G1 arrest of NIH-3T3 cells. Fluoridation of hydroxyapatite and different FHA and FA structure caused different cell response of NIH-3T3 cells to biomaterials.

  3. Controlled release of NELL-1 protein from chitosan/hydroxyapatite-modified TCP particles.

    PubMed

    Zhang, Yulong; Dong, Rui; Park, Yujin; Bohner, Marc; Zhang, Xinli; Ting, Kang; Soo, Chia; Wu, Benjamin M

    2016-09-10

    NEL-like molecule-1 (NELL-1) is a novel osteogenic protein that showing high specificity to osteochondral cells. It was widely used in bone regeneration research by loading onto carriers such as tricalcium phosphate (TCP) particles. However, there has been little research on protein controlled release from this material and its potential application. In this study, TCP was first modified with a hydroxyapatite coating followed by a chitosan coating to prepare chitosan/hydroxyapatite-coated TCP particles (Chi/HA-TCP). The preparation was characterized by SEM, EDX, FTIR, XRD, FM and Zeta potential measurements. The NELL-1 loaded Chi/HA-TCP particles and the release kinetics were investigated in vitro. It was observed that the Chi/HA-TCP particles prepared with the 0.3% (wt/wt) chitosan solution were able to successfully control the release of NELL-1 and maintain a slow, steady release for up to 28 days. Furthermore, more than 78% of the loaded protein's bioactivity was preserved in Chi/HA-TCP particles over the period of the investigation, which was significantly higher than that of the protein released from hydroxyapatite coated TCP (HA-TCP) particles. Collectively, this study suggests that the osteogenic protein NELL-1 showed a sustained release pattern after being encapsulated into the modified Chi/HA-TCP particles, and the NELL-1 integrated composite of Chi/HA-TCP showed a potential to function as a protein delivery carrier and as an improved bone matrix for use in bone regeneration research.

  4. The fabrication and characterization of biodegradable HA/PHBV nanoparticle-polymer composite scaffolds.

    PubMed

    Jack, Kevin S; Velayudhan, Shiny; Luckman, Paul; Trau, Matt; Grøndahl, Lisbeth; Cooper-White, Justin

    2009-09-01

    This study reports the fabrication and characterization of nano-sized hydroxyapatite (HA)/poly(hydroxyabutyrate-co-hydroxyvalerate) (PHBV) polymer composite scaffolds with high porosity and controlled pore architectures. These scaffolds were prepared using a modified thermally induced phase-separation technique. This investigation focuses on the effect of fabrication conditions on the overall pore architecture of the scaffolds and the dispersion of HA nanocrystals within the composite scaffolds. The morphologies, mechanical properties and in vitro bioactivity of the composite scaffolds were investigated. It was noted that the pore architectures could be manipulated by varying phase-separation parameters. The HA particles were dispersed in the pore walls of the scaffolds and were well bonded to the polymer. The introduction of HA greatly increased the stiffness and strength, and improved the in vitro bioactivity of the scaffolds. The results suggest these newly developed nano-HA/PHBV composite scaffolds may serve as an effective three-dimensional substrate in bone tissue engineering.

  5. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    NASA Astrophysics Data System (ADS)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Dragoş, Uţu

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  6. Nanocomposite bone scaffolds based on biodegradable polymers and hydroxyapatite.

    PubMed

    Becker, Johannes; Lu, Lichun; Runge, M Brett; Zeng, Heng; Yaszemski, Michael J; Dadsetan, Mahrokh

    2015-08-01

    In tissue engineering, development of an osteoconductive construct that integrates with host tissue remains a challenge. In this work, the effect of bone-like minerals on maturation of pre-osteoblast cells was investigated using polymer-mineral scaffolds composed of poly(propylene fumarate)-co-poly(caprolactone) (PPF-co-PCL) and nano-sized hydroxyapatite (HA). The HA of varying concentrations was added to an injectable formulation of PPF-co-PCL and the change in thermal and mechanical properties of the scaffolds was evaluated. No change in onset of degradation temperature was observed due to the addition of HA, however compressive and tensile moduli of copolymer changed significantly when HA amounts were increased in composite formulation. The change in mechanical properties of copolymer was found to correlate well to HA concentration in the constructs. Electron microscopy revealed mineral nucleation and a change in surface morphology and the presence of calcium and phosphate on surfaces was confirmed using energy dispersive X-ray analysis. To characterize the effect of mineral on attachment and maturation of pre-osteoblasts, W20-17 cells were seeded on HA/copolymer composites. We demonstrated that cells attached more to the surface of HA containing copolymers and their proliferation rate was significantly increased. Thus, these findings suggest that HA/PPF-co-PCL composite scaffolds are capable of inducing maturation of pre-osteoblasts and have the potential for use as scaffold in bone tissue engineering.

  7. Synthesis and characterization of hydroxyapatite from fish bone waste

    SciTech Connect

    Marliana, Ana Fitriani, Eka; Ramadhan, Fauzan; Suhandono, Steven; Yuliani, Keti; Windarti, Tri

    2015-12-29

    Waste fish bones is a problem stemming from activities in the field of fisheries and it has not been used optimally. Fish bones contain calcium as natural source that used to synthesize hydroxyapatite (HA). In this research, HA synthesized from waste fish bones as local wisdom in Semarang. The goal are to produce HA with cheaper production costs and to reduce the environmental problems caused by waste bones. The novelty of this study was using of local fish bone as a source of calcium and simple method of synthesis. Synthesis process of HA can be done through a maceration process with firing temperatures of 1000°C or followed by a sol-gel method with firing at 550°C. The results are analyzed using FTIR (Fourier Transform Infrared), XRD (X-Ray Diffraction) and SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray). FTIR spectra showed absorption of phosphate and OH group belonging to HA as evidenced by the results of XRD. The average grain size by maceration and synthesized results are not significant different, which is about 69 nm. The ratio of Ca/P of HA by maceration result is 0.89, then increase after continued in the sol-gel process to 1.41. Morphology of HA by maceration results are regular and uniform particle growth, while the morphology of HA after the sol-gel process are irregular and agglomerated.

  8. Hydroxyapatite formed on/in agarose gel induces activation of blood coagulation and platelets aggregation.

    PubMed

    Arimura, Shin-ichiro; Kawahara, Ko-ichi; Biswas, Kamal Krishna; Abeyama, Kazuhiro; Tabata, Masashi; Shimoda, Toru; Ogomi, Daisuke; Matsusaki, Michiya; Kato, Shinya; Ito, Takashi; Sugihara, Kazumasa; Akashi, Mitsuru; Hashiguchi, Teruto; Maruyama, Ikuro

    2007-05-01

    We reported earlier that hydroxyapatite (HA) formed on/in agarose gels (HA/agarose) produced by alternate soaking process is a bone-filling material possessing osteoconductive and hemostatic effects. This process could allow us to make bone-like apatite that was formed on/in organic polymer hydrogel matrices. Here, we investigated the mechanism of hemostasis induced by HA/agarose and found that HA/agarose, but not agarose or HA powder, significantly shortened activated partial thromboplastin time (APTT). While HA/agarose did not show significant platelet aggregation, it markedly enhanced adenosine diphosphate (ADP)-induced platelet aggregation. Moreover, Western blot analysis revealed selective adsorption of vitronectin onto HA/agarose. We also observed marked differences between HA powder and HA/agarose in their XRD patterns. The crystallinity of HA powder was much higher compared to that of HA/agarose. Furthermore, 50-100 nm of tube-form aggregations was observed in HA powder on the other hand 100-200 nm of particles was observed in HA/agarose by SEM observation. Thus 100-200 nm of low crystallized particles on the surface structure of HA/agarose may play an important role in hemostasis. Our results demonstrated a crucial role of HA/agarose in the mechanism of hemostasis and suggested a potential role for HA/agarose as a bone-grafting material.

  9. Real-Time Protein and Cell Binding Measurements on Hydroxyapatite Coatings

    PubMed Central

    Vilardell, A. M.; Cinca, N.; Jokinen, A.; Garcia-Giralt, N.; Dosta, S.; Cano, I. G.; Guilemany, J. M.

    2016-01-01

    Although a lot of in vitro and in vivo assays have been performed during the last few decades years for hydroxyapatite bioactive coatings, there is a lack of exploitation of real-time in vitro interaction measurements. In the present work, real-time interactions for a plasma sprayed hydroxyapatite coating were measured by a Multi-Parametric Surface Plasmon Resonance (MP-SPR), and the results were compared with standard traditional cell viability in vitro assays. MP-SPR is proven to be suitable not only for measurement of molecule–molecule interactions but also molecule–material interaction measurements and cell interaction. Although SPR is extensively utilized in interaction studies, recent research of protein or cell adsorption on hydroxyapatite coatings for prostheses applications was not found. The as-sprayed hydroxyapatite coating resulted in 62.4% of crystalline phase and an average thickness of 24 ± 6 μm. The MP-SPR was used to measure lysozyme protein and human mesenchymal stem cells interaction to the hydroxyapatite coating. A comparison between the standard gold sensor and Hydroxyapatite (HA)-plasma coated sensor denoted a clearly favourable cell attachment on HA coated sensor as a significantly higher signal of cell binding was detected. Moreover, traditional cell viability and proliferation tests showed increased activity with culture time indicating that cells were proliferating on HA coating. Cells show homogeneous distribution and proliferation along the HA surface between one and seven days with no significant mortality. Cells were flattened and spread on rough surfaces from the first day, with increasing cytoplasmatic extensions during the culture time. PMID:27618911

  10. Bioactive glass/hydroxyapatite composites: mechanical properties and biological evaluation.

    PubMed

    Bellucci, Devis; Sola, Antonella; Anesi, Alexandre; Salvatori, Roberta; Chiarini, Luigi; Cannillo, Valeria

    2015-06-01

    Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the samples at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference samples due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the samples themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth.

  11. Deposition of hydroxyapatite thin films by Nd:YAG laser ablation: a microstructural study

    SciTech Connect

    Nistor, L.C.; Ghica, C.; Teodorescu, V.S.; Nistor, S.V. . E-mail: snistor@alpha1.infim.ro; Dinescu, M.; Matei, D.; Frangis, N.; Vouroutzis, N.; Liutas, C.

    2004-11-02

    Hydroxyapatite (HA) thin films has been successfully deposited by Nd:YAG laser ablation at {lambda} = 532 nm. The morphology and microstructure of the deposited layers was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Polycrystalline HA films were directly obtained with the substrate at 300 deg. C and without introducing water vapors in the deposition chamber. Electron paramagnetic resonance (EPR) measurements show that the oxygen stoichiometry in the HA films is also maintained. Depositions performed at {lambda} = 335 nm laser wavelength and 300 deg. C substrate temperature resulted in polycrystalline layers of mixed composition of HA and tricalciumphosphate (TCP)

  12. Metal containing polymeric functional microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1979-01-01

    Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing. After collection of the labeled cells, the magnetic field is discontinued and the labeled sub-cell population recovered.

  13. Hydroxyapatite for Keratoprosthesis Biointegration

    PubMed Central

    Wang, Liqiang; Jeong, Kyung Jae; Chiang, Homer H.; Zurakowski, David; Behlau, Irmgard; Chodosh, James; Dohlman, Claes H.; Langer, Robert

    2011-01-01

    Purpose. Integration of keratoprosthesis with the surrounding cornea is very important in preventing bacterial invasion, which may cause ocular injury. Here the authors investigated whether hydroxyapatite (HAp) coating can improve keratoprosthesis (KPro) biointegration, using polymethyl methacrylate (PMMA)—the principal component of the Boston KPro—as a model polymer. Methods. HAp coatings were induced on PMMA discs after treatment with concentrated NaOH and coating with poly-dopamine (PDA) or polydopamine and then with 11-mercaptoundecanoic acid (11-MUA). Coatings were characterized chemically (Fourier transform infrared spectroscopy [FTIR], energy dispersive X-ray spectroscopy [EDX]) and morphologically (SEM) and were used as substrates for keratocyte growth in vitro. Cylinders of coated PMMA were implanted in porcine corneas ex vivo for 2 weeks, and the force required to pull them out was measured. The inflammatory reaction to coated discs was assessed in the rabbit cornea in vivo. Results. FTIR of the coatings showed absorption bands characteristic of phosphate groups, and EDX showed that the Ca/P ratios were close to those of HAp. By SEM, each method resulted in morphologically distinct HAp films; the 11-MUA group had the most uniform coating. The hydroxyapatite coatings caused comparable enhancement of keratocyte proliferation compared with unmodified PMMA surfaces. HAp coating significantly increased the force and work required to pull PMMA cylinders out of porcine corneas ex vivo. HAp coating of implants reduced the inflammatory response around the PMMA implants in vivo. Conclusions. These results are encouraging for the potential of HAp-coated surfaces for use in keratoprostheses. PMID:21849419

  14. Characterization and In Vitro Corrosion Investigations of Thermal Sprayed Hydroxyapatite and Hydroxyapatite-Titania Coatings on Ti Alloy

    NASA Astrophysics Data System (ADS)

    Sarao, Tejinder Pal Singh; Sidhu, Hazoor Singh; Singh, Harpreet

    2012-11-01

    In the current investigation, hydroxyapatite (HA) powder was mixed with titania (TiO2) in 50:50 wt pct for depositing composite coatings on a Ti-alloy substrate using a thermal-spray coating technique. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) analyses. The corrosion behavior of the coatings was studied by electrochemical corrosion testing in simulated human body fluid. After the corrosion testing, the samples were analyzed by XRD and SEM/EDS analyses. HA and TiO2 (rutile) were the main phases observed in the developed coatings. Bulk HA coating was amorphous; however, the addition of TiO2 effectively improved the crystallinity of HA in HA-TiO2 coating. The SEM analysis confirmed the formation of a well-formed HA-TiO2 composite coating. HA coating exhibited higher bond strength (67.8 MPa) compared with HA-TiO2 composite coating (37.6 MPa). The electrochemical study showed a significant improvement in the corrosion resistance of the Ti alloy after the deposition of the coatings.

  15. Characterization of Sr-substituted hydroxyapatite thin film by sputtering technique from mixture targets of hydroxyapatite and strontium apatite.

    PubMed

    Ozeki, K; Goto, T; Aoki, H; Masuzawa, T

    2014-01-01

    Sr-substituted hydroxyapatite thin films were prepared by sputtering technique from mixture targets of hydroxyapatite (HA) and strontium apatite (SrAp). The HA and SrAp powders were mixed at 0-100% Sr/(Sr+Ca) target ratios. The coated films were recrystallized by a hydrothermal treatment to reduce film dissolution. The films were then characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectrometry (ICP). The osteocompatiblity of the films was also evaluated by the size of the bone formation area in osteoblast cells.In the XRD patterns, peaks shifted to lower 2θ values with increasing Sr/(Sr+Ca) target ratios, which indicated Sr incorporation into the HA lattice. In the SEM observation of the hydrothermally treated films, the surface was covered with globular particles, and the size of the globular particles increased from Sr0 to Sr40, and then the size decreased from Sr60 to Sr100. The ICP analysis showed that the Sr/(Sr+Ca) film ratios were almost the same as the target ratios. In the cell culture, the bone formation area on the Sr-substituted HA films increased with increasing Sr concentration, and saturated at Sr60.

  16. Comparison of new bone formation, implant integration, and biocompatibility between RGD-hydroxyapatite and pure hydroxyapatite coating for cementless joint prostheses--an experimental study in rabbits.

    PubMed

    Bitschnau, Achim; Alt, Volker; Böhner, Felicitas; Heerich, Katharina Elisabeth; Margesin, Erika; Hartmann, Sonja; Sewing, Andreas; Meyer, Christof; Wenisch, Sabine; Schnettler, Reinhard

    2009-01-01

    This is the first work to report on additional Arginin-Glycin-Aspartat (RGD) coating on precoated hydroxyapatite (HA) surfaces regarding new bone formation, implant bone contact, and biocompatibility compared to pure HA coating and uncoated stainless K-wires. There were 39 rabbits in total with 6 animals for the RGD-HA and HA group for the 4 week time period and 9 animals for each of the 3 implant groups for the 12 week observation. A 2.0 K-wire either with RGD-HA or with pure HA coating or uncoated was placed into the intramedullary canal of the tibia. After 4 and 12 weeks, the tibiae were harvested and three different areas of the tibia were assessed for quantitative and qualitative histology for new bone formation, direct implant bone contact, and formation of multinucleated giant cells. Both RGD-HA and pure HA coating showed statistically higher new bone formation and implant bone contact after 12 weeks than the uncoated K-wire. There were no significant differences between the RGD-HA and the pure HA coating in new bone formation and direct implant bone contact after 4 and 12 weeks. The number of multinucleated giant did not differ significantly between the RGD-HA and HA group after both time points. Overall, no significant effects of an additional RGD coating on HA surfaces were detected in this model after 12 weeks.

  17. Monolithic Pellets, Composites and Thick Films of Hydroxyapatite: Correlation of Mechanical Properties with Microstructure.

    NASA Astrophysics Data System (ADS)

    Wang, Pauchiu Either

    Hydroxyapatite Ca_{10}(PO _4)_6(OH)_2 (abbreviated as HA) has great biocompatibility. Poor mechanical properties of HA implants and decomposition of HA during processing are the major obstacles for widespread uses of HA. In the present thesis we have attempted to understand the sintering behavior of monolithic HA and metal-reinforced HA-matrix composites, and the mechanism of formation of HA coating in the solutions at the normal temperature. The powders of two calcium phosphates, namely hydroxyapatite and dicalcium phosphate (DCP: chemical formula Ca_2P_2O_7), were sintered at various temperatures and in various environments. The density, flexural strength and knoop hardness of both phosphates sintered in air for 4 h initially increased with the sintering temperature, reaching maxima at around 1000-1150 ^circC, and then decreased due to decomposition. To reduce dehydroxylation, HA powder was sintered in moisture at various temperatures up to 1350^circ C and X-ray diffraction study did not indicate any decomposition at the highest sintering temperature. It is seen that dehydroxylation did not hinder sintering, but decomposition obstructed sintering of both HA and DCP. Ductile-phase reinforcement of hydroxyapatite was achieved by addition of silver particulates (5-30 vol.%) in HA powder compacts. A composite made by sintering 10 vol.% Ag and balance HA at 1200^circ C for 1 h in air had flexural strength of 75 +/- 7 MPa, which was almost double that of pure HA sintered under an identical condition. Silver in the composite melted during sintering, but due to poor wetting, did not spread in between HA particles. The increase in the flexural strength of the composites was thought to be due to crack-bridging and crack-arrest by silver inclusions. Thick films (several μm) of hydroxyapatite were deposited on silicon single crystal placed in close proximity to a plate of apatite- and wollastonite -containing glass and dipped into a simulated body fluid (SBF) at 36^circ

  18. Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue.

    PubMed

    Romero, Maria J R H; Nakashima, Syozi; Nikaido, Toru; Ichinose, Shizuko; Sadr, Alireza; Tagami, Junji

    2015-08-01

    Salivary phosphoproteins are essential in tooth mineral regulation but are often overlooked in vitro. This study aimed to evaluate the effect of casein, as a salivary phosphoprotein homologue, on the deposition and growth of hydroxyapatite (HA) on tooth surfaces. Hydroxyapatite growth was quantified using seeded crystal systems. Artificial saliva (AS) containing HA powder and 0, 10, 20, 50, or 100 μg ml(-1) of casein, or 100 μg ml(-1) of dephosphorylated casein (Dcasein), was incubated for 0-8 h at 37°C, pH 7.2. Calcium concentrations were measured using atomic absorption spectroscopy (AAS). Surface precipitation of HA on bovine enamel and dentine blocks, incubated in similar conditions for 7 d, was examined using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Casein adsorption was assessed using modified Lowry assays and zeta-potential measurements. The AAS results revealed a concentration-dependent inhibition of calcium consumption. Hydroxyapatite precipitation occurred when no casein was present, whereas precipitation of HA was apparently completely inhibited in casein-containing groups. Adsorption data demonstrated increasingly negative zeta-potential with increased casein concentration and an affinity constant similar to proline-rich proteins with Langmuir modelling. Casein inhibited the deposition and growth of HA primarily through the binding of esterized phosphate to HA active sites, indicating its potential as a mineral-regulating salivary phosphoprotein homologue in vitro.

  19. Synthesis and characterization of TEP-EDTA-regulated bioactive hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Haders, Daniel Joseph, II

    Hydroxyapatite (HA), Ca10(PO4)6(OH) 2, the stoichiometric equivalent of the ceramic phase of bone, is the preferred material for hard tissue replacement due to its bioactivity. However, bioinert metals are utilized in load-bearing orthopedic applications due to the poor mechanical properties of HA. Consequently, attention has been given to HA coatings for metallic orthopedic implants to take advantage of the bioactivity of HA and the mechanical properties of metals. Commercially, the plasma spray process (PS-HA) is the method most often used to deposit HA films on metallic implants. Since its introduction in the 1980's, however, concerns have been raised about the consequences of PS-HA's low crystallinity, lack of phase purity, lack of film-substrate chemical adhesion, passivation properties, and difficulty in coating complex geometries. Thus, there is a need to develop inexpensive reproducible next-generation HA film deposition techniques, which deposit high crystallinity, phase pure, adhesive, passivating, conformal HA films on clinical metallic substrates. The aim of this dissertation was to intelligently synthesize and characterize the material and biological properties of HA films on metallic substrates synthesized by hydrothermal crystallization, using thermodynamic phase diagrams as the starting point. In three overlapping interdisciplinary studies the potential of using ethylenediamine-tetraacetic acid/triethyl phosphate (EDTA/TEP) doubly regulated hydrothermal crystallization to deposit HA films, the TEP-regulated, time-and-temperature-dependent process by which films were deposited, and the bioactivity of crystallographically engineered films were investigated. Films were crystallized in a 0.232 molal Ca(NO3)2-0.232 molal EDTA-0.187 molal TEP-1.852 molal KOH-H2O chemical system at 200°C. Thermodynamic phase diagrams demonstrated that the chosen conditions were expected to produce Ca-P phase pure HA, which was experimentally confirmed. EDTA regulation of

  20. Photonic crystal microspheres

    NASA Astrophysics Data System (ADS)

    Zhokhov, A. A.; Masalov, V. M.; Sukhinina, N. S.; Matveev, D. V.; Dolganov, P. V.; Dolganov, V. K.; Emelchenko, G. A.

    2015-11-01

    Spherical samples of photonic crystals formed by colloidal SiO2 nanoparticles were synthesized. Synthesis of microspheres from 160 nm, 200 nm and 430 nm diameter colloidal nanoparticles was performed over a wide size range, from 5 μm to 50 μm. The mechanism of formation of void microparticles exceeding 50 μm is discussed. The spectral measurements verified the association of the spectra with the peaks of selective reflection from the cubic lattice planes. The microparticle morphology is characterized by scanning electron microscopy (SEM).

  1. Chalcogenide glass microsphere laser.

    PubMed

    Elliott, Gregor R; Murugan, G Senthil; Wilkinson, James S; Zervas, Michalis N; Hewak, Daniel W

    2010-12-06

    Laser action has been demonstrated in chalcogenide glass microsphere. A sub millimeter neodymium-doped gallium lanthanum sulphide glass sphere was pumped at 808 nm with a laser diode and single and multimode laser action demonstrated at wavelengths between 1075 and 1086 nm. The gallium lanthanum sulphide family of glass offer higher thermal stability compared to other chalcogenide glasses, and this, along with an optimized Q-factor for the microcavity allowed laser action to be achieved. When varying the pump power, changes in the output spectrum suggest nonlinear and/or thermal effects have a strong effect on laser action.

  2. Multi and mixed 3D-printing of graphene-hydroxyapatite hybrid materials for complex tissue engineering.

    PubMed

    Jakus, Adam E; Shah, Ramille N

    2017-01-01

    With the emergence of three-dimensional (3D)-printing (3DP) as a vital tool in tissue engineering and medicine, there is an ever growing need to develop new biomaterials that can be 3D-printed and also emulate the compositional, structural, and functional complexities of human tissues and organs. In this work, we probe the 3D-printable biomaterials spectrum by combining two recently established functional 3D-printable particle-laden biomaterial inks: one that contains hydroxyapatite microspheres (hyperelastic bone, HB) and another that contains graphene nanoflakes (3D-graphene, 3DG). We demonstrate that not only can these distinct, osteogenic, and neurogenic inks be co-3D-printed to create complex, multimaterial constructs, but that composite inks of HB and 3DG can also be synthesized. Specifically, the printability, microstructural, mechanical, electrical, and biological properties of a hybrid material comprised of 1:1 HA:graphene by volume is investigated. The resulting HB-3DG hybrid exhibits mixed characteristics of the two distinct systems, while maintaining 3D-printability, electrical conductivity, and flexibility. In vitro assessment of HB-3DG using mesenchymal stem cells demonstrates the hybrid material supports cell viability and proliferation, as well as significantly upregulates both osteogenic and neurogenic gene expression over 14 days. This work ultimately demonstrates a significant step forward towards being able to 3D-print graded, multicompositional, and multifunctional constructs from hybrid inks for complex composite tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 274-283, 2017.

  3. Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration

    NASA Technical Reports Server (NTRS)

    Thomson, R. C.; Yaszemski, M. J.; Powers, J. M.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

  4. Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration.

    PubMed

    Thomson, R C; Yaszemski, M J; Powers, J M; Mikos, A G

    1998-11-01

    A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

  5. Nano-hydroxyapatite and its applications in preventive, restorative and regenerative dentistry: a review of literature

    PubMed Central

    Pepla, Erlind; Besharat, Lait Kostantinos; Palaia, Gaspare; Tenore, Gianluca; Migliau, Guido

    2014-01-01

    Summary This study aims to critically summarize the literature about nano-hydroxyapatite. The purpose of this work is to analyze the benefits of using nano-hydroxyapatite in dentistry, especially for its preventive, restorative and regenerative applications. We also provide an overview of new dental materials, still experimental, which contain the nano-hydroxyapatite in its nano-crystalline form. Hydroxyapatite is one of the most studied biomaterials in the medical field for its proven biocompatibility and for being the main constituent of the mineral part of bone and teeth. In terms of restorative and preventive dentistry, nano-hydroxyapatite has significant remineralizing effects on initial enamel lesions, certainly superior to conventional fluoride, and good results on the sensitivity of the teeth. The nano-HA has also been used as an additive material, in order to improve already existing and widely used dental materials, in the restorative field (experimental addition to conventional glass ionomer cements, that has led to significant improvements in their mechanical properties). Because of its unique properties, such as the ability to chemically bond to bone, to not induce toxicity or inflammation and to stimulate bone growth through a direct action on osteoblasts, nano-HA has been widely used in periodontology and in oral and maxillofacial surgery. Its use in oral implantology, however, is a widely used practice established for years, as this substance has excellent osteoinductive capacity and improves bone-to-implant integration. PMID:25506416

  6. Nano-hydroxyapatite and its applications in preventive, restorative and regenerative dentistry: a review of literature.

    PubMed

    Pepla, Erlind; Besharat, Lait Kostantinos; Palaia, Gaspare; Tenore, Gianluca; Migliau, Guido

    2014-07-01

    This study aims to critically summarize the literature about nano-hydroxyapatite. The purpose of this work is to analyze the benefits of using nano-hydroxyapatite in dentistry, especially for its preventive, restorative and regenerative applications. We also provide an overview of new dental materials, still experimental, which contain the nano-hydroxyapatite in its nano-crystalline form. Hydroxyapatite is one of the most studied biomaterials in the medical field for its proven biocompatibility and for being the main constituent of the mineral part of bone and teeth. In terms of restorative and preventive dentistry, nano-hydroxyapatite has significant remineralizing effects on initial enamel lesions, certainly superior to conventional fluoride, and good results on the sensitivity of the teeth. The nano-HA has also been used as an additive material, in order to improve already existing and widely used dental materials, in the restorative field (experimental addition to conventional glass ionomer cements, that has led to significant improvements in their mechanical properties). Because of its unique properties, such as the ability to chemically bond to bone, to not induce toxicity or inflammation and to stimulate bone growth through a direct action on osteoblasts, nano-HA has been widely used in periodontology and in oral and maxillofacial surgery. Its use in oral implantology, however, is a widely used practice established for years, as this substance has excellent osteoinductive capacity and improves bone-to-implant integration.

  7. Preparation and evaluation of the in vitro drug release properties and mucoadhesion of novel microspheres of hyaluronic acid and chitosan.

    PubMed

    Lim, S T; Martin, G P; Berry, D J; Brown, M B

    2000-05-15

    Rapid mucociliary clearance of intranasally administered drugs is often a key factor in determining the bioavailability of such therapeutic agents. The use of mucoadhesive microparticles provide a potential strategy for improving retention of drugs within the nasal cavity, and thereby improve the resultant pharmacokinetic profile. This study describes the comparison of a number of novel, potentially mucoadhesive microspheres, prepared by solvent evaporation, composed of hyaluronic acid (HA), chitosan glutamate (CH) and a combination of the two with microcapsules of HA and gelatin prepared by complex coacervation. The microspheres had a mean particle size of 19.91+/-1.57 microm (HA), 28.60+/-1.34 microm (HA/CH), 29.47+/-3.58 microm (CH). The incorporation of a model drug, gentamicin sulphate (%) was 46.90+/-0.53 (HA), 28.04+/-1.21 (HA/CH) and 13.32+/-1.04 (CH). The in vitro release profiles of microsphere formulations prepared by solvent evaporation were determined. The release of gentamicin from HA and HA/CH was 50% longer than CH and was best modelled as a release from a matrix. The degree of mucoadhesion of each formulation was investigated by determining the mucociliary transport rate (MTR) of the microparticles across an isolated frog palate. Acacia/gelatin microcapsules were used as a positive control. The rank order of mucoadhesion for the microspheres and the microparticles was HA=HA/CH>CH>HA/gelatin>CHins. The entrapment of gentamicin did not affect the mucoadhesive properties (P>0.05, Mann--Whitney U-test). The combination of HA with chitosan may afford additional advantages in combining the mucoadhesive potential of HA with the penetration enhancing effect of chitosan.

  8. Hydroxyapatite-nanotube composites and coatings for orthopedic applications

    NASA Astrophysics Data System (ADS)

    Lahiri, Debrupa

    Hydroxyapatite (HA) has received wide attention in orthopedics, due to its biocompatibility and osseointegration ability. Despite these advantages, the brittle nature and low fracture toughness of HA often results in rapid wear and premature fracture of implant. Hence, there is a need to improve the fracture toughness and wear resistance of HA without compromising its biocompatibility. The aim of the current research is to explore the potential of nanotubes as reinforcement to HA for orthopedic implants. HA- 4 wt.% carbon nanotube (CNT) composites and coatings are synthesized by spark plasma sintering and plasma spraying respectively, and investigated for their mechanical, tribological and biological behavior. CNT reinforcement improves the fracture toughness (>90%) and wear resistance (>66%) of HA for coating and free standing composites. CNTs have demonstrated a positive influence on the proliferation, differentiation and matrix mineralization activities of osteoblasts, during in-vitro biocompatibility studies. In-vivo exposure of HA-CNT coated titanium implant in animal model (rat) shows excellent histocompatibility and neobone integration on the implant surface. The improved osseointegration due to presence of CNTs in HA is quantified by the adhesion strength measurement of single osteoblast using nano-scratch technique. Considering the ongoing debate about cytotoxicity of CNTs in the literature, the present study also suggests boron nitride nanotube (BNNT) as an alternative reinforcement. BNNT with the similar elastic modulus and strength as CNT, were added to HA. The resulting composite having 4 wt.% BNNTs improved the fracture toughness (˜85%) and wear resistance (˜75%) of HA in the similar range as HA-CNT composites. BNNTs were found to be non-cytotoxic for osteoblasts and macrophages. In-vitro evaluation shows positive role of BNNT in osteoblast proliferation and viability. Apatite formability of BNNT surface in ˜4 days establishes its osseointegration

  9. Nano hydroxyapatite-coated implants improve bone nanomechanical properties.

    PubMed

    Jimbo, R; Coelho, P G; Bryington, M; Baldassarri, M; Tovar, N; Currie, F; Hayashi, M; Janal, M N; Andersson, M; Ono, D; Vandeweghe, S; Wennerberg, A

    2012-12-01

    Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features; here we describe a nanoscale hydroxyapatite (HA)-coated implant surface and hypothesize that it will hasten osseointegration and improve its quality relative to that of non-coated implants. Twenty threaded titanium alloy implants, half prepared with a stable HA nanoparticle surface and half grit-blasted, acid-etched, and heat-treated (HT), were inserted into rabbit femurs. Pre-operatively, the implants were morphologically and topographically characterized. After 3 weeks of healing, the samples were retrieved for histomorphometry. The nanomechanical properties of the surrounding bone were evaluated by nanoindentation. While both implants revealed similar bone-to-implant contact, the nanoindentation demonstrated that the tissue quality was significantly enhanced around the HA-coated implants, validating the postulated hypothesis.

  10. Review of ferroelectric hydroxyapatite and its application to biomedicine

    NASA Astrophysics Data System (ADS)

    Lang, Sidney B.

    2016-08-01

    Hydroxyapatite (HA) is a major component of bone in humans and animals. Until about 10 years ago, it was considered to have a centrosymmetric crystal structure and could not contribute to the well-known piezoelectric effect in bone. This review describes the theoretical and experimental studies that showed that HA does have a non-centrosymmetric structure. Recent experiments have shown that HA exhibits piezoelectricity, pyroelectricity, and ferroelectricity. It has been made in the form of thick films and as space-charge electrets. It has an important biomedical application as an implant for bone cell attachment and growth. This paper is contributed in honor of the 80th birthday of my long-time friend and colleague, Bozena Hilczer.

  11. New Coll-HA/BT composite materials for hard tissue engineering.

    PubMed

    Zanfir, Andrei Vlad; Voicu, Georgeta; Busuioc, Cristina; Jinga, Sorin Ion; Albu, Madalina Georgiana; Iordache, Florin

    2016-05-01

    The integration of ceramic powders in composite materials for bone scaffolds can improve the osseointegration process. This work was aimed to the synthesis and characterization of new collagen-hydroxyapatite/barium titanate (Coll-HA/BT) composite materials starting from barium titanate (BT) nanopowder, hydroxyapatite (HA) nanopowder and collagen (Coll) gel. BT nanopowder was produced by combining two wet-chemical approaches, sol-gel and hydrothermal methods. The resulting materials were characterized in terms of phase composition and microstructure by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Moreover, the biocompatibility and bioactivity of the composite materials were assessed by in vitro tests. The synthesized BT particles exhibit an average size of around 35 nm and a spherical morphology, with a pseudo-cubic or tetragonal symmetry. The diffraction spectra of Coll-HA and Coll-HA/BT composite materials indicate a pronounced interaction between Col and the mineral phases, meaning a good mineralization of Col fibres. As well, the in vitro tests highlight excellent osteoinductive properties for all biological samples, especially for Coll-HA/BT composite materials, fact that can be attributed to the ferromagnetic properties of BT.

  12. Lysozyme loading and release from Se doped hydroxyapatite nanoparticles.

    PubMed

    Wang, Yanhua; Hao, Hang; Zhang, Shengmin

    2016-04-01

    Element-substituted hydroxyapatite (HA) based nanocomposites have become a promising therapeutic material for improving bone defect repair. Selenium substituted HA nanoparticles can both induce apoptosis of bone tumor cells and enhance osteointegration. However, the effect of selenite ions on the proteins in combination with the HA nanoparticles remains to be elucidated. Here, we investigated the influence of selenium doping concentration on the loading and release of lysozyme (LSM) as a model protein drug. The selenium substituted HA-LSM composites with different doping concentrations were synthesized and characterized. The subsequent delivery of lysozyme was studied in a phosphate buffer solution (PBS). We found that selenium substituted HA-LSM composites with Se:P=10% showed the highest amount of lysozyme loading (41.7%), whereas the amount of lysozyme loaded in undoped HA nanoparticles was the lowest (34.1%). The doped selenium interacts with lysozyme molecules, which leads to the increase of β-sheet and unordered, and the decrease of self-association, α-helix and β-turns in protein structures. Moreover, selenium addition significantly slows the protein release from HA-LSM composites. The composites with Se:P=10% release lysozyme at the slightly slower rate among the samples with different Se doping concentrations. It also shows that the released lysozyme retains most of its enzymatic activity.

  13. New nuclide sup 263 Ha

    SciTech Connect

    Kratz, J.V.; Gober, M.K.; Zimmermann, H.P. ); Schaedel, M.; Bruechle, W.; Schimpf, E. ); Gregorich, K.E.; Tuerler, A.; Hannink, N.J.; Czerwinski, K.R.; Kadkhodayan, B.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. ); Gaeggeler, H.; Jost, D.; Kovacs, J.; Scherer, U.W.; Weber, A. )

    1992-03-01

    A new nuclide {sup 263}Ha was produced in the bombardment of a {sup 249}Bk target with 93-MeV {sup 18}O ions. It was detected via spontaneous fission counting and was shown to have a half-life of about 0.5 min. This activity was also separated from the reaction products by automated rapid chemical separations using cation-exchange chromatography in 0.05{ital M} {alpha}-hydroxyisobutyric acid. After chemical separation, {sup 263}Ha was found to decay by spontaneous fission (57{sub {minus}15}{sup +13}%) and by {alpha} emission ({ital E}{sub {alpha}}=8.35 MeV, 43%) with a half-life of 27{sub {minus}7}{sup +10} s. The spontaneous fission fragment energy spectrum is compatible with an average total kinetic energy of about 200 MeV.

  14. Interaction of stem cells with nano hydroxyapatite-fucoidan bionanocomposites for bone tissue regeneration.

    PubMed

    Tae Young, Ahn; Kang, Jeong Han; Kang, Dong Jun; Venkatesan, Jayachandran; Chang, Hee Kyung; Bhatnagar, Ira; Chang, Kwan-Young; Hwang, Jae-Ho; Salameh, Ziad; Kim, Se-Kwon; Kim, Hui Taek; Kim, Dong Gyu

    2016-12-01

    The combination of bioceramics with biopolymers are playing major role in the construction of artificial bone. Hydroxyapatite (HA) has been extensively studied as a material in bone repair and replacement in last two decades. In the present study, we have prepared the hydroxyapatite-fucoidan (HA-Fucoidan) nanocomposites by in situ chemical method and biologically characterized them for bone graft substitute. Biological results inferred that mineralization effect of HA-F nanocomposites shows significant enhancement compared to HA in adipose derived stem cell (ADSC). It may be due to the addition of fucoidan in the nanocomposites. The important gene expression such as osteocalcin, osteopontin, collagen and runx-2 were checked using ADSC with HA and HA-fucoidan nanocomposites and the results show that the enhancements were found at 7th day. Furthermore, we have performed in vivo study of HA-fucoidan nanocomposites with rabbit model and a slight amount of bone formation was observed in HA-fucoidan nanocomposites. Herewith, we suggest that HA-fucoidan nanocomposites will be good biomaterials for bone repair/replacement in future.

  15. Hydroxyapatite-anatase-carbon nanotube nanocomposite coatings fabricated by electrophoretic codeposition for biomedical applications.

    PubMed

    Zhang, Bokai; Kwok, Chi Tat

    2011-10-01

    In order to eliminate micro-cracks in the monolithic hydroxyapatite (HA) and composite hydroxyapatite/carbon nanotube (HA/CNT) coatings, novel HA/TiO(2)/CNT nanocomposite coatings on Ti6Al4V were attempted to fabricate by a single-step electrophoretic codeposition process for biomedical applications. The electrophoretically deposited layers with difference contents of HA, TiO(2) (anatase) and CNT nanoparticles were sintered at 800°C for densification with thickness of about 7-10 μm. A dense and crack-free coating was achieved with constituents of 85 wt% HA, 10 wt% TiO(2) and 5 wt% CNT. Open-circuit potential measurements and cyclic potentiodynamic polarization tests were used to investigate the electrochemical corrosion behavior of the coatings in vitro conditions (Hanks' solution at 37°C). The HA/TiO(2)/CNT coatings possess higher corrosion resistance than that of the Ti6Al4V substrate as reflected by nobler open circuit potential and lower corrosion current density. In addition, the surface hardness and adhesion strength of the HA/TiO(2)/CNT coatings are higher than that of the monolithic HA and HA/CNT coatings without compromising their apatite forming ability. The enhanced properties were attributed to the nanostructure of the coatings with the appropriate TiO(2) and CNT contents for eliminating micro-cracks and micro-pores.

  16. Microsphere based saliva diagnostics

    NASA Astrophysics Data System (ADS)

    Rissin, David M.; DiCesare, Christopher; Hayman, Ryan B.; Blicharz, Timothy M.; Walt, David R.

    2005-11-01

    Saliva presents a minimally invasive alternative medium to blood for performing diagnostics1. Microsphere sensors for ions, small organic molecules, and proteins are currently being developed and optical microarrays containing thousands of these sensors will be used for simultaneous multi-analyte analysis. The fiber bundle platform in use is 1mm in diameter and contains approximately 50,000 individually addressable 3.1μm fibers, each with an etched well capable of housing a single 3.1μm microsphere sensor. Micron-sized bead-based chemistries are produced in house, followed by deposition onto a fiber-optic bundle platform, allowing for multiplexed analysis. The ultimate goal is to develop a universal diagnostic system using saliva as the diagnostic medium. This platform will permit multiplexed analysis of a sample by integrating microfluidics with the optical arrays loaded with sensors capable of detecting relevant biomarkers associated with a wide range of disease states. Disease states that are currently under investigation include end stage renal disease (ESRD) and Sjoegrens Syndrome (SS).

  17. Towards Monodispersed Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Senuma, Yoshinori; Hilborn, Jons

    1998-03-01

    Uniform polymer microspheres prepared by Spinning Disk Atomization Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles of very narrow size distribution. Around the edge of the disk, small teeth channel the flow into identical droplets that are flung off over the disk rim. These solidify during flight to form spherical particles. Applications for spheres produced by SDA can be found in areas such as adhesives, powder coatings, food, biomedical use, drug delivery systems, etc. We have atomized polyethyleneglycol into very narrowly dispersed microspheres ranging from 50 to 500 =B5m. The aim of this work is to model the droplet formation occurring at the rim of the spinning disk in order to better understand the experimental results. The viscosity contribution in the fluid breakup is qualitatively analyzed and is adapted to the theoretical model to show how it affects the droplet size. We have used the pendant drop model (Ramesh Babu, S. Journal of Colloid and Interface Science 116, 350-372 (1987).) for spinning disk atomization to describe the drop-shape evolution during growth.

  18. Enhanced Mechanical Properties and Corrosion Behavior of Biodegradable Mg-Zn/HA Composite

    NASA Astrophysics Data System (ADS)

    Salleh, Emee Marina; Zuhailawati, Hussain; Ramakrishnan, Sivakumar; Dhindaw, Brij Kumar

    2017-03-01

    Magnesium (Mg) and its alloys have shown potential for use in the biomedical industry due to their excellent biological performance and biodegradability in the bioenvironment. Thus, the aim of the present study was to develop a reliable biodegradable hard tissue substituent. Biodegradable and bioactive Mg-Zinc (Zn) reinforced by hydroxyapatite (HA) composite was prepared using mechanically alloyed Mg-6.5 wt pct Zn and pure HA powders as starting materials. Various HA contents (i.e., 5, 10, 15, and 20 wt pct) were introduced in forming the Mg-Zn/HA composite. The effect of bioactive HA incorporation in biodegradable Mg-6.5 wt pct Zn alloy matrix on mechanical and biodegradation properties as well as microstructural observation was investigated. As measured by the Williamson-Hall formula, the Mg crystallite size of the sintered composites containing 5, 10, 15, and 20 wt pct HA were 36.76, 29.08, 27.93, and 27.31 nm, respectively. According to X-ray diffraction (XRD) analysis, there was no new crystalline phase formed during milling, indicating that no mechanochemical reactions between Mg-Zn alloy and HA occurred. The -1.70 V shifted significantly toward the passive position of the plain Mg-6.5 wt pct Zn alloy and Mg-Zn/10 wt pct HA composite, which were -1.50 and -1.46 V, respectively, indicating that the Mg-Zn/10 wt pct HA composite was least susceptible to corrosion in the bioenvironment.

  19. Electrospun PCL/PLA/HA based nanofibers as scaffold for osteoblast-like cells.

    PubMed

    Fang, Rui; Zhang, Enwei; Xu, Ling; Wei, Shicheng

    2010-11-01

    Polycaprolactone (PCL), poly (lactic acid) (PLA) and hydroxyapatite (HA) are frequently used as materials for tissue engineering. In this study, PCL/PLA/HA nanofiber mats with different weight ratio were prepared using electrospinning. Their structure and morphology were studied by FTIR and FESEM. FTIR results demonstrated that the HA particles were successfully incorporated into the PCL/PLA nanofibers. The FESEM images showed that the surface of fibers became coarser with the introduction of HA nanoparticles into PCL/PLA system. Furthermore, the addition of HA led to the decreasing of fiber diameter. The average diameters of PCL/PLA/HA nanofiber were in the range of 300-600 nm, while that of PCL/PLA was 776 +/- 15.4 nm. The effect of nanofiber composition on the osteoblast-like MC3T3-E1 cell adhesion and proliferation were investigated as the preliminary biological evaluation of the scaffold. The MC3T3-E1 cell could be attached actively on all the scaffolds. The MTT assay revealed that PCL/PLA/HA scaffold shows significantly higher cell proliferation than PCL/PLA scaffolds. After 15 days of culture, mineral particles on the surface of the cells was appeared on PCL/PLA/HA nanofibers while normal cell spreading morphology on PCL/PLA nanofibers. These results manifested that electrospun PCL/PLA/HA scaffolds could enhance bone regeneration, showing their marvelous prospect as scaffolds for bone tissue engineering.

  20. Silicon addition to hydroxyapatite increases nanoscale electrostatic, van der Waals, and adhesive interactions.

    PubMed

    Vandiver, Jennifer; Dean, Delphine; Patel, Nelesh; Botelho, Claudia; Best, Serena; Santos, José D; Lopes, Maria A; Bonfield, William; Ortiz, Christine

    2006-08-01

    The normal intersurface forces between nanosized probe tips functionalized with COO(-)-terminated alkanethiol self-assembling monolayers and dense, polycrystalline silicon-substituted synthetic hydroxyapatite (SiHA) and phase pure hydroxyapatite (HA) were measured via a nanomechanical technique called chemically specific high-resolution force spectroscopy. A significantly larger van der Waals interaction was observed for the SiHA compared to HA; Hamaker constants (A) were found to be A(SiHA) = 35 +/- 27 zJ and A(HA) = 13 +/- 12 zJ. Using the Derjaguin-Landau-Verwey-Overbeek approximation, which assumes linear additivity of the electrostatic double layer and van der Waals components, and the nonlinear Poisson-Boltzmann surface charge model for electrostatic double-layer forces, the surface charge per unit area, sigma (C/m(2)), was calculated as a function of position for specific nanosized areas within individual grains. SiHA was observed to be more negatively charged than HA with sigma(SiHA) = -0.024 +/- 0.013 C/m(2), two times greater than sigma(HA) = -0.011 +/- 0.006 C/m(2). Additionally, SiHA was found to have increased surface adhesion (0.7 +/- 0.3 nN) compared to HA (0.5 +/- 0.3 nN). The characterization of the nanoscale variations in surface forces of SiHA and HA will enable an improved understanding of the initial stages of bone-biomaterial bonding.

  1. The influence of plasma technology coupled to chemical grafting on the cell growth compliance of 3D hydroxyapatite scaffolds.

    PubMed

    Russo, Laura; Zanini, Stefano; Giannoni, Paolo; Landi, Elena; Villa, Anna; Sandri, Monica; Riccardi, Claudia; Quarto, Rodolfo; Doglia, Silvia M; Nicotra, Francesco; Cipolla, Laura

    2012-11-01

    The development of advanced materials with biomimetic features in order to elicit desired biological responses and to guarantee tissue biocompatibility is recently gaining attention for tissue engineering applications. Bioceramics, such as hydroxyapatite-based biomaterials are now used in a number of different applications throughout the body, covering all areas of the skeleton, due to their biological and chemical similarity to the inorganic phases of bones. When bioactive sintered hydroxyapatite (HA) is desired, biomolecular modification of these materials is needed. In the present work, we investigated the influence of plasma surface modification coupled to chemical grafting on the cell growth compliance of HA 3D scaffolds.

  2. Hydroxyapatite synthesis on solid surfaces using a biological approach

    NASA Astrophysics Data System (ADS)

    Wang, A.; Mei, J.; Tse, Y. Y.; Jones, I. P.; Sammons, R. L.

    2012-12-01

    Many naturally occurring mineralisation processes yield hydroxyapatite (HA) or related salts, but biological routes to calcification have not generally been exploited for production of hydroxyapatite for clinical and industrial applications. Serratia sp. NCIMB 40259 is a non-pathogenic Gram-negative bacterium which is capable of growing as a biofilm on many surfaces and can be used to form HA coatings on a variety of polymeric and metallic materials, including titanium. Here we review previous work and report the results of more recent studies on the influence of titanium compositional and surface properties on Serratia adherence and proliferation and biomineralisation on commercially pure titanium (cp Ti) discs and a Ti mesh. Bacterial adherence was equivalent on cpTi and Ti6Al4V, and biofilms formed on both rough and mirror-polished cpTi surfaces. Embedded alumina particles and alkali treatment did not noticeably alter the precipitation of Serratia HA, nor the structure of the coating in comparison with non-treated substrates. Coatings were retained after sintering at 800°C in argon, although the original curved plate-like crystals changed to nano-scale β-tricalcium phosphate particles. A phosphorous-rich diffusion zone formed at the coating-titanium interface. Bacterial mineralisation may have applications as a method for producing coatings on implants in non load-bearing sites, and non-clinical applications where a high surface area is the major concern.

  3. Rabbit synoviocyte inositol phospholipid metabolism is stimulated by hydroxyapatite crystals

    SciTech Connect

    Rothenberg, R.J.; Cheung, H.

    1988-04-01

    Inhibition of prostaglandin E2 synthesis partially ameliorates some aspects of synovitis, but joint destruction still progresses. Other aspects of phospholipid metabolism may play a role in synovial tissue pathophysiology. Products of phosphatidylinositol metabolism can activate intracellular processes in response to extracellular stimuli. We asked whether this pathway is activated in synoviocytes in monolayer tissue culture by the addition of hydroxyapatite (HA) crystals in medium. These crystals are found in pathological human synovial fluid. These crystals are associated with the secretion of degradative enzymes and with a destructive arthritis in humans. Rabbit synoviocyte cultures, previously incubated with (3H)inositol to label inositol phospholipids, were stimulated with the addition of hydroxyapatite (180 micrograms/ml) to the cultures. There was enhanced intracellular accumulation of (3H)inositol monophosphate (30-100%) after 4 h. This indicated an increased phospholipase C activity. The radioactivity in (3H)inositol bis- and trisphosphates was too low to reliably measure. The use of (32P)Pi allowed detection of these compounds. In the presence of HA, incorporation of (32P)Pi into phosphatidylinositol, phosphatidylinositol monophosphate, and phosphatidylinositol bisphosphate was increased. In addition, cultures exposed to (32P)Pi during stimulation with HA had an increased content of (32P)inositol monophosphate, bisphosphate, and trisphosphate.

  4. The role of amino acids in hydroxyapatite mineralization

    PubMed Central

    2016-01-01

    Polar and charged amino acids (AAs) are heavily expressed in non-collagenous proteins (NCPs), and are involved in hydroxyapatite (HA) mineralization in bone. Here, we review what is known on the effect of single AAs on HA precipitation. Negatively charged AAs, such as aspartic acid, glutamic acid (Glu) and phosphoserine are largely expressed in NCPs and play a critical role in controlling HA nucleation and growth. Positively charged ones such as arginine (Arg) or lysine (Lys) are heavily involved in HA nucleation within extracellular matrix proteins such as collagen. Glu, Arg and Lys intake can also increase bone mineral density by stimulating growth hormone production. In vitro studies suggest that the role of AAs in controlling HA precipitation is affected by their mobility. While dissolved AAs are able to inhibit HA precipitation and growth by chelating Ca2+ and PO43− ions or binding to nuclei of calcium phosphate and preventing their further growth, AAs bound to surfaces can promote HA precipitation by attracting Ca2+ and PO43− ions and increasing the local supersaturation. Overall, the effect of AAs on HA precipitation is worth being investigated more, especially under conditions closer to the physiological ones, where the presence of other factors such as collagen, mineralization inhibitors, and cells heavily influences HA precipitation. A deeper understanding of the role of AAs in HA mineralization will increase our fundamental knowledge related to bone formation, and could lead to new therapies to improve bone regeneration in damaged tissues or cure pathological diseases caused by excessive mineralization in tissues such as cartilage, blood vessels and cardiac valves. PMID:27707904

  5. Hydroxyapatite-alumina composites and bone-bonding.

    PubMed

    Li, J; Fartash, B; Hermansson, L

    1995-03-01

    Hydroxyapatite-alumina (HA/Al2O3) composites, with HA contents of 15, 25, 30 and 70, and pure HA as well as pure Al2O3, were densified at 1275 degrees C at a top pressure of 200 MPa for 2 h, using glass-encapsulated hot isostatic pressing. From the sintered ceramics, cylinders 2.8 x 6 mm2 were prepared by ultrasonic machining and implanted into the femoral cortical bones of 12 New Zealand White rabbits for 3 months. After killing the animals, the femur was dissected out and cut into three sections, each containing one cylinder. The specimens were mounted in a push-out device and force was applied along the long axis of the cylinder. The maximum force required to loosen the implant was recorded and the fracture surface of the bone implant was studied by scanning electron microscopy (SEM). The results indicate the important role of HA in new bone apposition to the implants, reflected by increasing bonding strength with increasing HA content in the composites. However, the relationship between HA content and the bonding strength was not linear. The composite with 70% HA and the pure HA ceramic had the same level of bonding strength and similar fracture interfaces in SEM, which supports the high bonding strength detected (about 15 MPa). Fractures occurred both in the bone and in the implant, indicating the stress transfer ability of the contact zone. This study presents qualitatively and quantitatively HA-dependent characteristics in bone-bonding. The mechanical strength of the composites was measured by a three-point bending test. The bending strength of the materials decreases with increasing HA content.

  6. A comparative study of zinc, magnesium, strontium-incorporated hydroxyapatite-coated titanium implants for osseointegration of osteopenic rats.

    PubMed

    Tao, Zhou-Shan; Zhou, Wan-Shu; He, Xing-Wen; Liu, Wei; Bai, Bing-Li; Zhou, Qiang; Huang, Zheng-Liang; Tu, Kai-kai; Li, Hang; Sun, Tao; Lv, Yang-Xun; Cui, Wei; Yang, Lei

    2016-05-01

    Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for the implants in cementless arthroplasty. However, its effect is not sufficient for osteoporotic bone. Zinc (Zn), magnesium (Mg), and strontium (Sr) present a beneficial effect on bone growth, and positively affect bone regeneration. The aim of this study was to confirm the different effects of the fixation strength of Zn, Mg, Sr-substituted hydroxyapatite-coated (Zn-HA-coated, Mg-HA-coated, Sr-HA-coated) titanium implants via electrochemical deposition in the osteoporotic condition. Female Sprague-Dawley rats were used for this study. Twelve weeks after bilateral ovariectomy, all animals were randomly divided into four groups: group HA; group Zn-HA; group Mg-HA and group Sr-HA. Afterwards, all rats from groups HA, Zn-HA, Mg-HA and Sr-HA received implants with hydroxyapatite containing 0%, 10% Zn ions, 10% Mg ions, and 10% Sr ions. Implants were inserted bilaterally in all animals until death at 12 weeks. The bilateral femurs of rats were harvested for evaluation. All treatment groups increased new bone formation around the surface of titanium rods and push-out force; group Sr-HA showed the strongest effects on new bone formation and biomechanical strength. Additionally, there are significant differences in bone formation and push-out force was observed between groups Zn-HA and Mg-HA. This finding suggests that Zn, Mg, Sr-substituted hydroxyapatite coatings can improve implant osseointegration, and the 10% Sr coating exhibited the best properties for implant osseointegration among the tested coatings in osteoporosis rats.

  7. Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC).

    PubMed

    Gu, Y W; Yap, A U J; Cheang, P; Khor, K A

    2005-03-01

    Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time.

  8. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  9. Hydroxyapatite-magnetite-MWCNT nanocomposite as a biocompatible multifunctional drug delivery system for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Pistone, Alessandro; Iannazzo, Daniela; Panseri, Silvia; Montesi, Monica; Tampieri, Anna; Galvagno, Signorino

    2014-10-01

    New magnetic hydroxyapatite-based nanomaterials as bone-specific systems for controlled drug delivery have been synthesized. The synthesized hydroxyapatite, HA, decorated with magnetite nanoparticles by a deposition method (HA/Fe3O4) and the nanocomposite system obtained using magnetic multi-walled carbon nanotubes (HA/MWCNT/Fe3O4) as a filler for HA have been characterized by chemical and morphological analyses, and their biological behavior was investigated. The systems have also been doped with clodronate in order to combine the effect of bone biomineralization induced by hydroxyapatite-based composites with the decrease of osteoclast formation induced by the drug. An analysis of the preosteoclastic RAW264.7 cell proliferation by MTT assay confirmed the high biocompatibility of the three systems. TRAP staining of RAW 264.7 conditioned with sRAKL to induce osteoclastogenesis, cultured in the presence of the systems doped and undoped with clodronate, showed the inhibitory effect of clodronate after we counted the MNC TRAP+cells but only in the osteoclast formation; in particular, the system HA/Fe3O4-Clo exerted a high inhibitory effect compared to the drug alone. These results demonstrate that the synthesized nanocomposites are a biocompatible magnetic drug delivery system and can represent a useful multimodal platform for applications in bone tissue engineering.

  10. Mechanical properties of natural chitosan/hydroxyapatite/magnetite nanocomposites for tissue engineering applications.

    PubMed

    Heidari, Fatemeh; Razavi, Mehdi; E Bahrololoom, Mohammad; Bazargan-Lari, Reza; Vashaee, Daryoosh; Kotturi, Hari; Tayebi, Lobat

    2016-08-01

    Chitosan (CS), hydroxyapatite (HA), and magnetite (Fe3O4) have been broadly employed for bone treatment applications. Having a hybrid biomaterial composed of the aforementioned constituents not only accumulates the useful characteristics of each component, but also provides outstanding composite properties. In the present research, mechanical properties of pure CS, CS/HA, CS/HA/magnetite, and CS/magnetite were evaluated by the measurements of bending strength, elastic modulus, compressive strength and hardness values. Moreover, the morphology of the bending fracture surfaces were characterized using a scanning electron microscope (SEM) and an image analyzer. Studies were also conducted to examine the biological response of the human Mesenchymal Stem Cells (hMSCs) on different composites. We conclude that, although all of these composites possess in-vitro biocompatibility, adding hydroxyapatite and magnetite to the chitosan matrix can noticeably enhance the mechanical properties of the pure chitosan.

  11. Fluor-hydroxyapatite sol-gel coating on titanium substrate for hard tissue implants.

    PubMed

    Kim, Hae-Won; Kim, Hyoun-Ee; Knowles, Jonathan C

    2004-08-01

    Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) films were deposited on a titanium substrate using a sol-gel technique. Different concentrations of F- were incorporated into the apatite structure during the sol preparation. Typical apatite structures were obtained for all coatings after dipping and subsequent heat treatment at 500 degrees C. The films obtained were uniform and dense, with a thickness of approximately 5 microm. The dissolution rate of the coating layer decreased with increasing F- incorporation within the apatite structure, which demonstrates the possibility of tailoring the solubility by a functional gradient coating of HA and FHA. The cell proliferation rate on the coating layer decreased slightly with increasing F- incorporation. The alkaline phosphatase (ALP) activity of the cells on all the HA and FHA coated samples showed much higher expression levels compared to pure Ti. This confirmed the improved activity of cell functions on the substrates with the sol-gel coating treatment.

  12. Micro- and nanostructured hydroxyapatite-collagen microcarriers for bone tissue-engineering applications.

    PubMed

    Perez, R A; Altankov, G; Jorge-Herrero, E; Ginebra, M P

    2013-05-01

    Novel hydroxyapatite (HA)-collagen microcarriers (MCs) with different micro/nanostructures were developed for bone tissue-engineering applications. The MCs were fabricated via calcium phosphate cement (CPC) emulsion in oil. Collagen incorporation in the liquid phase of the CPC resulted in higher MC sphericity. The MCs consisted of a porous network of entangled hydroxyapatite crystals, formed as a result of the CPC setting reaction. The addition of collagen to the MCs, even in an amount as small as 0.8 wt%, resulted in an improved interaction with osteoblast-like Saos-2 cells. The micro/nanostructure and the surface texture of the MCs were further tailored by modifying the initial particle size of the CPC. A synergistic effect between the presence of collagen and the nanosized HA crystals was found, resulting in significantly enhanced alkaline phosphatase activity on the collagen-containing nanosized HA MCs.

  13. Effects of hydroxyapatite and Biostite on osteogenic induction of hMSC.

    PubMed

    Marinucci, Lorella; Balloni, Stefania; Becchetti, Ennio; Bistoni, Giovanni; Calvi, Edoardo Maria; Lumare, Eleonora; Ederli, Filippo; Locci, Paola

    2010-03-01

    When isolated from the iliac crest human mesenchymal stem cells (hMSC) differentiate into osteoblast-like cells with appropriate stimulation in culture. This in vitro study tested the hypothesis that Biostite and hydroxyapatite (HA) affect proliferation and differentiation of hMSC into osteoblastic cells. Cell proliferation was determined by measuring 3H-thymidine incorporation into DNA and typical markers of osteoblastic phenotype were determined by RT-PCR assay. No differences emerged in cell proliferation cultures with Biostite or hydroxyapatite (HA), but gene expression analysis revealed higher expression of collagen,alkaline phosphatase (ALP), osteopontin and bone sialoprotein (BSP) in the presence of Biostite. TGFb2 production, as assessed by an Elisa kit, and Runx2 expression by RT-PCR, were greater in Biostite cultures, suggesting Biostite provides a better environment for hMSC differentiation into osteoblasts and is, potentially, a more promising bone-filling material than HA.

  14. Influence of hydroxyapatite on the corrosion resistance of the Ti-13Nb-13Zr alloy.

    PubMed

    Duarte, Laís T; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

    2009-05-01

    Electrochemical analyses on the biocompatible alloy Ti-13Nb-13Zr wt% in an electrolyte simulating physiological medium (PBS solution) are reported. Hydroxyapatite (HA) films were obtained on the alloy by electrodeposition at constant cathodic current. Samples of the alloy covered with an anodic-oxide film or an anodic-oxide/HA film were analyzed by open circuit potential and electrochemical impedance spectroscopy measurements during 180 days in the PBS electrolyte. Analyses of the open-circuit potential (E (oc)) values indicated that the oxide/HA film presents better protection characteristics than the oxide only. This behavior was corroborated by the higher film resistances obtained from impedance data, indicating that, besides improving the alloy osteointegration, the hydroxyapatite film may also increase the corrosion protection of the biomaterial.

  15. Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: dissolution behaviour and biological properties after crystallisation.

    PubMed

    Tredwin, Christopher J; Young, Anne M; Abou Neel, Ensanya A; Georgiou, George; Knowles, Jonathan C

    2014-01-01

    Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) were synthesised by the sol-gel method as possible implant coating or bone-grafting materials. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride were incorporated for the preparation of the FHA and FA sol-gels. After heating and powdering the sol-gels, dissolution behaviour was assessed using ion chromatography to measure Ca(2+) and PO4 (3-) ion release. Biological behaviour was assessed using cellular proliferation with human osteosarcoma cells and alamarBlue™ assay. Statistical analysis was performed with a two way analysis of variance and post hoc testing with a Bonferroni correction. Increasing fluoride substitution into an apatite structure decreased the dissolution rate. Increasing the firing temperature of the HA, FHA and FA sol-gels up to 1,000 °C decreased the dissolution rate. There was significantly higher cellular proliferation on highly substituted FHA and FA than on HA or Titanium. The properties of an implant coating or bone grafting material can be tailored to meet specific requirements by altering the amount of fluoride that is incorporated into the original apatite structure. The dissolution behaviour can further be altered by the temperature at which the sol-gel is fired.

  16. Mechanism of Zn stabilization in hydroxyapatite and hydrated (0 0 1) surfaces of hydroxyapatite.

    PubMed

    Matos, M; Terra, J; Ellis, D E

    2010-04-14

    A basic understanding of Zn incorporation on bulk and hydrated (0 0 1) surfaces of hydroxyapatite (HA) is attained through electronic structure calculations which use a combined first principles density functional (DFT) and extended Hückel tight binding (EHTB) methodology. A Zn substituted hydroxyapatite relaxed structure is obtained through a periodic cell DFT geometry optimization method. Electronic structure properties are calculated by using both cluster DFT and periodic cell EHTB methods. Bond order calculations show that Zn preference for the Ca2 vacancy, near the OH channel and with greater structural flexibility, is associated with the formation of a four-fold (bulk) and nearly four-fold (surface) coordination, as in ZnO. When occupying the octahedral Ca1 vacancy, Zn remains six-fold in the bulk, but coordination decreases to five-fold in the surface. In the bulk and surface, Zn2 is found to be more covalent than Zn1, due to a decrease in bond lengths at the four-fold site, which approach the 1.99 Å ZnO value. Zn is however considerably less bound in the biomaterial than in the oxide, where calculated bond orders are twice as large as in HA. Surface phosphate groups (PO(4)) and hydroxide ions behave as compact individual units as in the bulk; no evidence is found for the presence of HPO(4). Ca-O bond orders decrease at the surface, with a consequent increase in ionicity. Comparison between DFT and EHTB results show that the latter method gives a good qualitative account of charge and bonding in these systems.

  17. Fabrication of HA/PHBV composite scaffolds through the emulsion freezing/freeze-drying process and characterisation of the scaffolds.

    PubMed

    Sultana, Naznin; Wang, Min

    2008-07-01

    Biodegradable polymer-based scaffolds containing osteoconductive hydroxyapatite (HA) particles can be very useful for bone tissue engineering. In this investigation, HA nanoparticles were incorporated in poly(hydroxybutyrate-co-valerate) (PHBV) polymer to fabricate osteoconductive composite scaffolds. PHBV and HA/PHBV scaffolds were made using an emulsion freezing/freeze-drying technique. The scaffolds produced were subsequently characterized using several techniques. It was found that the scaffolds were highly porous and had interconnected porous structures. The pore size ranged from several microns to around 300 microm. The spherical HA nanoparticles which were produced in-house through a nanoemulsion process could be incorporated into composite scaffolds although some of these nanoparticles existed on the surface of pore walls when a relatively large amount of HA was used for composite scaffolds. The incorporation of HA nanoparticles also enhanced compressive mechanical properties of the scaffolds.

  18. Bacterial Cellulose-Hydroxyapatite Nanocomposites for Bone Regeneration

    PubMed Central

    Saska, S.; Barud, H. S.; Gaspar, A. M. M.; Marchetto, R.; Ribeiro, S. J. L.; Messaddeq, Y.

    2011-01-01

    The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA) nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl2 followed by Na2HPO4. BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40%–50% of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA), similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration. PMID:21961004

  19. Osteoconductive hydroxyapatite coated PEEK for spinal fusion surgery

    NASA Astrophysics Data System (ADS)

    Hahn, Byung-Dong; Park, Dong-Soo; Choi, Jong-Jin; Ryu, Jungho; Yoon, Woon-Ha; Choi, Joon-Hwan; Kim, Jong-Woo; Ahn, Cheol-Woo; Kim, Hyoun-Ee; Yoon, Byung-Ho; Jung, In-Kwon

    2013-10-01

    Polyetheretherketone (PEEK) has attracted much interest as biomaterial for interbody fusion cages due to its similar stiffness to bone and good radio-transparency for post-op visualization. Hydroxyapatite (HA) coating stimulates bone growth to the medical implant. The objective of this work is to make an implant consisting of biocompatible PEEK with an osteoconductive HA surface for spinal or orthopedic applications. Highly dense and well-adhered HA coating was developed on medical-grade PEEK using aerosol deposition (AD) without thermal degradation of the PEEK. The HA coating had a dense microstructure with no cracks or pores, and showed good adhesion to PEEK at adhesion strengths above 14.3 MPa. The crystallinity of the HA coating was remarkably enhanced by hydrothermal annealing as post-deposition heat-treatment. In addition, in vitro and in vivo biocompatibility of PEEK, in terms of cell adhesion morphology, cell proliferation, differentiation, and bone-to-implant contact ratio, were remarkably enhanced by the HA coating through AD.

  20. Development of electrochemical folic acid sensor based on hydroxyapatite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kanchana, P.; Sekar, C.

    2015-02-01

    We report the synthesis of hydroxyapatite (HA) nanoparticles (NPs) by a simple microwave irradiation method and its application as sensing element for the precise determination of folic acid (FA) by electrochemical method. The structure and composition of the HA NPs characterized using XRD, FTIR, Raman and XPS. SEM and EDX studies confirmed the formation of elongated spherical shaped HA NPs with an average particle size of about 34 nm. The HA NPs thin film on glassy carbon electrode (GCE) were deposited by drop casting method. Electrocatalytic behavior of FA in the physiological pH 7.0 was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. The fabricated HA/GCE exhibited a linear calibration plot over a wide FA concentration ranging from 1.0 × 10-7 to 3.5 × 10-4 M with the detection limit of 75 nM. In addition, the HA NPs modified GCE showed good selectivity toward the determination of FA even in the presence of a 100-fold excess of ascorbic acid (AA) and 1000-fold excess of other common interferents. The fabricated biosensor exhibits good sensitivity and stability, and was successfully applied for the determination of FA in pharmaceutical samples.

  1. Electrophoretic deposition of composite hydroxyapatite-silica-chitosan coatings

    SciTech Connect

    Grandfield, K.; Zhitomirsky, I.

    2008-01-15

    Electrophoretic deposition (EPD) method has been developed for the fabrication of nanocomposite silica-chitosan coatings. Cathodic deposits were obtained on various conductive substrates using suspensions of silica nanoparticles in a mixed ethanol-water solvent, containing dissolved chitosan. Co-deposition of silica and hydroxyapatite (HA) nanoparticles resulted in the fabrication of HA-silica-chitosan coatings. The deposition yield has been studied at a constant voltage mode at various deposition durations. The method enabled the formation of coatings of different thickness in the range of up to 100 {mu}m. Deposit composition, microstructure and porosity can be varied by variation of HA and silica concentration in the suspensions. It was demonstrated that EPD can be used for the fabrication of HA-silica-chitosan coatings of graded composition and laminates. The method enabled the deposition of coatings containing layers of silica-chitosan and HA-chitosan nanocomposites using suspensions with different HA and silica content. Obtained coatings were studied by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy and energy dispersive spectroscopy. The mechanism of deposition is discussed.

  2. Augmentation of engineered cartilage to bone integration using hydroxyapatite.

    PubMed

    Dua, Rupak; Centeno, Jerry; Ramaswamy, Sharan

    2014-07-01

    Articular cartilage injuries occur frequently in the knee joint. Photopolymerizable cartilage tissue engineering approaches appear promising; however, fundamentally, forming a stable interface between the subchondral bone and tissue engineered cartilage components remains a major challenge. We investigated the utility of hydroxyapatite (HA) nanoparticles to promote controlled bone-growth across the bone-cartilage interface in an in vitro engineered tissue model system using bone marrow derived stem cells. Samples incorporated with HA demonstrated significantly higher interfacial shear strength (at the junction between engineered cartilage and engineered bone) compared with the constructs without HA (p < 0.05), after 28 days of culture. Interestingly, this increased interfacial shear strength due to the presence of HA was observed as early as 7 days and appeared to have sustained itself for an additional three weeks without interacting with strength increases attributable to subsequent secretion of engineered tissue matrix. Histological evidence showed that there was ∼7.5% bone in-growth into the cartilage region from the bone side. The mechanism of enhanced engineered cartilage to bone integration with HA incorporation appeared to be facilitated by the deposition of calcium phosphate in the transition zone. These findings indicate that controlled bone in-growth using HA incorporation permits more stable anchorage of the injectable hydrogel-based engineered cartilage construct via augmented integration between bone and cartilage.

  3. Formation and bioactivity of HA nanorods on micro-arc oxidized zirconium.

    PubMed

    Zhang, Lan; Zhu, Shaoyu; Han, Yong; Xiao, Chengzhang; Tang, Wu

    2014-10-01

    A microporous and CaO partially stabilized zirconia (Ca-PSZ) coating covered with hydroxyapatite (HA) nanorods is fabricated on Zr substrate by a hybrid approach of micro-arc oxidation (MAO) and hydrothermal treatment (HT). The effect of P ions in HT solution on the density and morphology of HA was investigated; the hydrophilicity and apatite-forming ability of the Ca-PSZ coating with HA nanorods were also examined. High-density HA nanorods (with a mean diameter of 50 nm and length of 450 nm) grow on the Ca-PSZ coating after HT in a solution containing 0.002 M β-glycerophosphate disodium (β-GP). However, only a few of coarse-grained HA crystallites grow in the MAOed pores after HT in distilled water or in an ammonia aqueous solution with an initial pH value equal to the solution containing 0.002 M β-GP. P ions in the HT solution are thought to significantly promote the formation of HA nanorods. The Ca-PSZ coating covered with HA nanorods displays good hydrophilicity and excellent apatite-inducing ability, and the induced apatite prefers to nucleate on the basal-faceted surfaces of HA nanorods.

  4. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

  5. Modulating protein adsorption onto hydroxyapatite particles using different amino acid treatments

    PubMed Central

    Lee, Wing-Hin; Loo, Ching-Yee; Van, Kim Linh; Zavgorodniy, Alexander V.; Rohanizadeh, Ramin

    2012-01-01

    Hydroxyapatite (HA) is a material of choice for bone grafts owing to its chemical and structural similarities to the mineral phase of hard tissues. The combination of osteogenic proteins with HA materials that carry and deliver the proteins to the bone-defective areas will accelerate bone regeneration. The study investigated the treatment of HA particles with different amino acids such as serine (Ser), asparagine (Asn), aspartic acid (Asp) and arginine (Arg) to enhance the adsorption ability of HA carrier for delivering therapeutic proteins to the body. The crystallinity of HA reduced when amino acids were added during HA preparation. Depending on the types of amino acid, the specific surface area of the amino acid-functionalized HA particles varied from 105 to 149 m2 g–1. Bovine serum albumin (BSA) and lysozyme were used as model proteins for adsorption study. The protein adsorption onto the surface of amino acid-functionalized HA depended on the polarities of HA particles, whereby, compared with lysozyme, BSA demonstrated higher affinity towards positively charged Arg-HA. Alternatively, the binding affinity of lysozyme onto the negatively charged Asp-HA was higher when compared with BSA. The BSA and lysozyme adsorptions onto the amino acid-functionalized HA fitted better into the Freundlich than Langmuir model. The amino acid-functionalized HA particles that had higher protein adsorption demonstrated a lower protein-release rate. PMID:21957116

  6. Characterization, mechanical properties and corrosion resistance of biocompatible Zn-HA/TiO2 nanocomposite coatings.

    PubMed

    Mirak, Mohammad; Alizadeh, Morteza; Ghaffari, Mohammad; Ashtiani, Mohammad Najafi

    2016-09-01

    Biocompatible Zinc-hydroxyapatite-titania and Zinc-hydroxyapatite nanocomposite coatings have been prepared by electrodeposition on NiTi shape memory alloy. Structures of coatings were characterized using X-ray diffraction (XRD). It was found that addition of TiO2 particles cause to reduction of crystallite size of coating. Scanning Electronic Microscope (SEM) observation showed that the Zn-HA/TiO2 coating consists of plate-like regions which can express that this plate-like structure can facilitate bone growth. X-ray photoelectron microscope (XPS) was performed to investigation of chemical state of composite coating and showed that Zinc matrix was bonded to oxygen. high-resolution transmission electron microscope (HRTEM) result illustrated the crystalline structure of nanocomposite coating. Mechanical behavior of coating was evaluated using microhardness and ball on disk wear test. The TiO2 incorporated composite coatings exhibited the better hardness and anti-wear performance than the Zn-HA coatings. Polarization measurements have been used to evaluate the electrochemical coatings performance. The Zn-HA/TiO2 composite coatings showed the highest corrosion resistance compared with Zn-HA and bare NiTi.

  7. Surface modification of titanium by nano-TiO 2/HA bioceramic coating

    NASA Astrophysics Data System (ADS)

    He, G.; Hu, J.; Wei, S. C.; Li, J. H.; Liang, X. H.; Luo, E.

    2008-11-01

    A nano-TiO 2/hydroxyapatite composite bioceramic coating was developed and applied to the surfaces of pure titanium discs by the sol-gel method. A TiO 2 anatase bioceramic coating was utilized in the inner layer, which could adhere tightly to the titanium substrate. A porous hydroxyapatite (HA) bioceramic coating was utilized in the outer layer, which has higher solubility and better short-term bioactivity. Conventional HA coatings and commercially pure titanium were used as controls. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the crystallization, surface morphology, and thickness of the coatings. The bioactivities of the coatings were evaluated by in vitro osteoblast cultures. Results showed that the nano-TiO 2/HA composite bioceramic coating exhibited good crystallization and homogeneous, nano-scale surface morphology. In addition, the nano-TiO 2/HA coating adhered tightly to the substrate, and the in vitro osteoblast cultures exhibited satisfactory bioactivity.

  8. Synthesis and photoluminescence study of flower-like hydroxyapatite nanostructure for bioprobe applications

    NASA Astrophysics Data System (ADS)

    Kumar, G. Suresh; Girija, E. K.; Thamizhavel, A.

    2013-02-01

    Biocompatible luminescent materials have received much attention for the development of novel bioprobes. In the present work, we have synthesized the flower-like hydroxyapatite (HA) nanostructure from eggshell biowaste via a simple and rapid microwave conversion process. The synthesized product is identified as Mg containing B-type carbonated HA. It showed an intense blue emission between 360 nm to 550 nm with maximum around 430 nm under UV light excitation (λex= 344 nm). This blue emission might result from the carbonate related impurities present in the structure of HA and it can be a potential luminescent material for the development biocompatible probes.

  9. Biodegradation rate of shellac coated bovine hydroxyapatite for bone filler material

    NASA Astrophysics Data System (ADS)

    Triyono, Joko; Triyono, Susilowati, Endang; Murdiyantara, Suci Anindya

    2016-03-01

    This work reports on the effect of shellac coated hydroxyapatite (HA) on the biodegradation rate. The HA was processed from bovine bone. Shellac was derived from the resinous secretion of the lac insect. The aims of the addition of shellac solution is to know how the biodegradation rate material in the Phosphate Buffered Saline (PBS) solution. The four different of shellac solutions (2,5%; 5%; 7,5%; and 10% weight) coated HA scaffoldand one ratio as a control. It was concluded that the ability of biodegradation rate a materialwas not influenced by the ratio of shellac. All materials were biodegradedwhen they were soaked in PBS solution.

  10. Glass reinforced hydroxyapatite for hard tissue surgery--part 1: Mechanical properties.

    PubMed

    Georgiou, G; Knowles, J C

    2001-10-01

    Commercial hydroxyapatite (HA) was reinforced by adding 2.5 and 5 wt% of a Na2O-CaO-P2O5 glass and then sintered. The resulting composites have chemical compositions that are similar to the inorganic constituent of the mineral part of bone, and are closely related to the trace elements that are present, in this case Na. X-ray diffraction showed no decomposition of HA to secondary phases; however, the glass reinforced-HA composites contained a HA phase and variable amounts of tricalcium phosphate phase, depending on the sintering temperature and the amount of glass added. The HA-composite material exhibited higher flexural strength overall compared to sintered HA. The presence of secondary phases beta- and alpha-tricalcium phosphate in the microstructure of the composites has a major influence on the mechanical properties. Additionally, the presence of porosity also has a bearing on the mechanical properties of the material.

  11. Nanostructural Characteristics of Vacuum Cold-Sprayed Hydroxyapatite/Graphene-Nanosheet Coatings for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Huang, Jing; Li, Hua

    2014-10-01

    Development of novel biocompatible nanomaterials has provided insights into their potential biomedical applications. Bulk fabrication of the nanomaterials in the form of coatings remains challenging. Here, we report hydroxyapatite (HA)/graphene-nanosheet (GN) composite coatings deposited by vacuum cold spray (VCS). Significant shape changes of HA nanograins during the coating deposition were revealed. The nanostructural features of HA together with curvature alternation of GN gave rise to dense structures. Based on the microstructural characterization, a structure model was proposed to elucidate the nanostructural characteristics of the HA-GN nanocomposites. Results also showed that addition of GN significantly enhanced fracture toughness and elastic modulus of the HA-based coatings, which is presumably accounted for by crack bridging offered by GN in the composites. The VCS HA-GN coatings show potential for biomedical applications for the repair or replacement of hard tissues.

  12. Removal of heavy metal ions by biogenic hydroxyapatite: Morphology influence and mechanism study

    NASA Astrophysics Data System (ADS)

    Wang, Dandan; Guan, Xiaomei; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Chen, Jun; Long, Haibo

    2016-08-01

    Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb2+, Cu2+, Mn2+, Zn2+. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb2+ ion was 99.97%. The mechanism of Pb2+ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

  13. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites.

    PubMed

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Supová, Monika; Zaloudková, Margit; Balík, Karel; Lisá, Věra; Slouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0-N25 or M0-M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%-15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%-15% (v/v) nano-size or micro-size HA seems to be optimum.

  14. Evaluation of hydroxyapatite-bioglass and hydroxyapatite-ethyl vinyl acetate composite extracts on antioxidant defense mechanism and genotoxicity: an in vitro study.

    PubMed

    Arun, M; Silja, P K; Mohanan, P V

    2011-09-01

    Hydroxyapatite-bioglass (HA BG) and hydroxyapatite-ethyl vinyl acetate (HA EVA) are two composite materials that have been developed for bone substitution. Their activity on antioxidant defense mechanism and genotoxicity has not been investigated before. To further confirm its biocompatibility, the present study was undertaken to investigate the effect of HA BG and HA EVA on mice liver antioxidant mechanism along with chromosomal aberrations in human lymphocytes. Physiological saline extract of HA BG and HA EVA showed no adverse effect on liver antioxidant mechanism compared to the cyclophosphamide (CP)-induced toxicity on mice liver homogenate. The results were judged from the in vitro studies made on reduced glutathione, glutathione reductase and lipid peroxidation. These results were well supported by CP- and mytomycin C (MC)-induced genotoxicity studies on human lymphocytes in the presence and absence of a metabolic activator (S9). Hence, it was suggested that these tests could be considered for preliminary toxicological screening of materials intended for clinical applications ahead of in vivo animal model evaluation.

  15. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

    PubMed Central

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Šupová, Monika; Žaloudková, Margit; Balík, Karel; Lisá, Věra; Šlouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

  16. SEM and EDX studies of bioactive hydroxyapatite coatings on titanium implants.

    PubMed

    Ciobanu, Gabriela; Carja, Gabriela; Ciobanu, Octavian; Sandu, Ion; Sandu, Andrei

    2009-01-01

    This work presents a study on an alternative coating method based on biomimetic techniques which are designed to form a crystalline hydroxyapatite layer very similar to the process corresponding to the formation of natural bone. The HA formation on the surface of titanium alloy pretreated with NaOH solution is investigated. Two types of solutions such as supersaturated calcification solution (SCS) and modified SCS (M-SCS) were used to investigate bone-like apatite formation on alkali-treated titanium. The hydroxyapatite deposits are investigated by means of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The data suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on titanium substrates.

  17. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, W.E.

    1982-09-30

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  18. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, William E.

    1984-01-01

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  19. Controlled Release of Interleukin-1 Receptor Antagonist from Hyaluronic Acid-Chitosan Microspheres Attenuates Interleukin-1β-Induced Inflammation and Apoptosis in Chondrocytes

    PubMed Central

    Qiu, Bo; Gong, Ming; He, Qi-Ting

    2016-01-01

    This paper investigates the protective effect of interleukin-1 receptor antagonist (IL-1Ra) released from hyaluronic acid chitosan (HA-CS) microspheres in a controlled manner on IL-1β-induced inflammation and apoptosis in chondrocytes. The IL-1Ra release kinetics was characterized by an initial burst release, which was reduced to a linear release over eight days. Chondrocytes were stimulated with 10 ng/ml IL-1β and subsequently incubated with HA-CS-IL-1Ra microspheres. The cell viability was decreased by IL-1β, which was attenuated by HA-CS-IL-1Ra microspheres as indicated by an MTT assay. ELISA showed that HA-CS-IL-1Ra microspheres inhibited IL-1β-induced inflammation by attenuating increases in NO2− and prostaglandin E2 levels as well as increase in glycosaminoglycan release. A terminal deoxyribonucleotide transferase deoxyuridine triphosphate nick-end labeling assay revealed that the IL-1β-induced chondrocyte apoptosis was decreased by HA-CS-IL-1Ra microspheres. Moreover, HA-CS-IL-1Ra microspheres blocked IL-1β-induced chondrocyte apoptosis by increasing B-cell lymphoma 2 (Bcl-2) and decreasing Bcl-2-associated X protein and caspase-3 expressions at mRNA and protein levels, as indicated by reverse-transcription quantitative polymerase chain reaction and western blot analysis, respectively. The results of the present study indicated that HA-CS-IL-1Ra microspheres as a controlled release system of IL-1Ra possess potential anti-inflammatory and antiapoptotic properties in rat chondrocytes due to their ability to regulate inflammatory factors and apoptosis associated genes. PMID:27872853

  20. Microspheres and their methods of preparation

    DOEpatents

    Bose, Anima B; Yang, Junbing

    2015-03-24

    Carbon microspheres are doped with boron to enhance the electrical and physical properties of the microspheres. The boron-doped carbon microspheres are formed by a CVD process in which a catalyst, carbon source and boron source are evaporated, heated and deposited onto an inert substrate.

  1. Does hydroxyapatite coating have no advantage over porous coating in primary total hip arthroplasty? A meta-analysis.

    PubMed

    Chen, Yun-Lin; Lin, Tiao; Liu, An; Shi, Ming-Min; Hu, Bin; Shi, Zhong-Li; Yan, Shi-Gui

    2015-01-28

    There are some arguments between the use of hydroxyapatite and porous coating. Some studies have shown that there is no difference between these two coatings in total hip arthroplasty (THA), while several other studies have shown that hydroxyapatite has advantages over the porous one. We have collected the studies in Pubmed, MEDLINE, EMBASE, and the Cochrane library from the earliest possible years to present, with the search strategy of "(HA OR hydroxyapatite) AND ((total hip arthroplasty) OR (total hip replacement)) AND (RCT* OR randomiz* OR control* OR compar* OR trial*)". The randomized controlled trials and comparative observation trials that evaluated the clinical and radiographic effects between hydroxyapatite coating and porous coating were included. Our main outcome measurements were Harris hip score (HHS) and survival, while the secondary outcome measurements were osteolysis, radiolucent lines, and polyethylene wear. Twelve RCTs and 9 comparative observation trials were included. Hydroxyapatite coating could improve the HHS (p < 0.01), reduce the incidence of thigh pain (p = 0.01), and reduce the incidence of femoral osteolysis (p = 0.01), but hydroxyapatite coating had no advantages on survival (p = 0.32), polyethylene wear (p = 0.08), and radiolucent lines (p = 0.78). Hydroxyapatite coating has shown to have an advantage over porous coating. The HHS and survival was duration-dependent-if given the sufficient duration of follow-up, hydroxyapatite coating would be better than porous coating for the survival. The properties of hydroxyapatite and the implant design had influence on thigh pain incidence, femoral osteolysis, and polyethylene wear. Thickness of 50 to 80 μm and purity larger than 90% increased the thigh pain incidence. Anatomic design had less polyethylene wear.

  2. Characterization of dicalcium phosphate dihydrate cements prepared using a novel hydroxyapatite-based formulation.

    PubMed

    Alge, Daniel L; Santa Cruz, Grace; Goebel, W Scott; Chu, Tien-Min Gabriel

    2009-04-01

    Dicalcium phosphate dihydrate (DCPD) cements are typically prepared using beta-tricalcium phosphate (beta-TCP) as the base component. However, hydroxyapatite (HA) is an interesting alternative because of its potential for reducing cement acidity, as well as modulating cement properties via ionic substitutions. In the present study, we have characterized DCPD cements prepared with a novel formulation based on monocalcium phosphate monohydrate (MCPM) and HA. Cements were prepared using a 4:1 MCPM:HA molar ratio. The reactivity of HA in this system was verified by showing DCPD formation using poorly crystalline HA, as well as highly crystalline HA. Evaluation of cements prepared with poorly crystalline HA revealed that setting occurs rapidly in the MCPM/HA system, and that the use of a setting regulator is necessary to maintain workability of the cement paste. Compressive testing showed that MCPM/HA cements have strengths comparable to what has previously been published for DCPD cements. However, preliminary in vitro analysis of cement degradation revealed that conversion of DCPD to HA may occur much more rapidly in the MCPM/HA system compared to cements prepared with beta-TCP. Future studies should investigate this property further, as it could have important implications for the use of HA-based DCPD cement formulations.

  3. XPS and bioactivity study of the bisphosphonate pamidronate adsorbed onto plasma sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    McLeod, Kate; Kumar, Sunil; Smart, Roger St. C.; Dutta, Naba; Voelcker, Nicolas H.; Anderson, Gail I.; Sekel, Ron

    2006-12-01

    This paper reports the use of X-ray photoelectron spectroscopy (XPS) to investigate bisphosphonate (BP) adsorption onto plasma sprayed hydroxyapatite (HA) coatings commonly used for orthopaedic implants. BPs exhibit high binding affinity for the calcium present in HA and hence can be adsorbed onto HA-coated implants to exploit their beneficial properties for improved bone growth at the implant interface. A rigorous XPS analysis of pamidronate, a commonly used nitrogenous BP, adsorbed onto plasma sprayed HA-coated cobalt-chromium substrates has been carried out, aimed at: (a) confirming the adsorption of this BP onto HA; (b) studying the BP diffusion profile in the HA coating by employing the technique of XPS depth profiling; (c) confirming the bioactivity of the adsorbed BP. XPS spectra of plasma sprayed HA-coated discs exposed to a 10 mM aqueous BP solution (pamidronate) for periods of 1, 2 and 24 h showed nitrogen and phosphorous photoelectron signals corresponding to the BP, confirming its adsorption onto the HA substrate. XPS depth profiling of the 2 h BP-exposed HA discs showed penetration of the BP into the HA matrix to depths of at least 260 nm. The bioactivity of the adsorbed BP was confirmed by the observed inhibition of osteoclast (bone resorbing) cell activity. In comparison to the HA sample, the HA sample with adsorbed BP exhibited a 25-fold decrease in primary osteoclast cells.

  4. Mechanical and morphologic investigation of the tensile strength of a bone-hydroxyapatite interface.

    PubMed

    Edwards, J T; Brunski, J B; Higuchi, H W

    1997-09-15

    For load-bearing calcium-phosphate biomaterials, it is important to understand the relative contributions of direct physical-chemical bonding vs. mechanical interlocking to interfacial strength. In the limit of a perfectly smooth hydroxyapatite (HA) surface, a tensile test of the bone-HA interface affords an opportunity to isolate the bonding contribution related to HA surface chemistry alone. This study measured the bone-HA interfacial tensile strength for highly polished (approximately 0.05 micron alumina) dense HA disks (5.25 mm in diameter, 1.3 in mm thickness) in rabbit tibiae. Each of five rabbits received four HA disks, two per proximal tibia. Pull-off loads ranged from 3.14 +/- 2.38N at 55 days after implantation to 18.35 +/- 11.9N at 88 days; nominal interfacial tensile strengths were 0.15 +/- 0.11 MPa and 0.85 +/- 0.55 MPa, respectively. SEM of failed interfaces revealed failures between HA and bone, within the HA itself and within adjacent bone. Tissue remnants on HA were identified as mineralized bone with either a lamellar or trabecular structure. Oriented collagen fibers in the bone intricately interdigitated with the HA surface, which frequently showed breakdown at material grain boundaries and a rougher surface than originally implanted. Mechanical interlocking could not be eliminated as a mode of tissue attachment and contribution to bone-HA bonding, even after implanting an extremely smooth HA surface.

  5. Quantification of carbon nanotube induced adhesion of osteoblast on hydroxyapatite using nano-scratch technique

    NASA Astrophysics Data System (ADS)

    Lahiri, Debrupa; Benaduce, Ana Paula; Kos, Lidia; Agarwal, Arvind

    2011-09-01

    This paper explores the nano-scratch technique for measuring the adhesion strength of a single osteoblast cell on a hydroxyapatite (HA) surface reinforced with carbon nanotubes (CNTs). This technique efficiently separates out the contribution of the environment (culture medium and substrate) from the measured adhesion force of the cell, which is a major limitation of the existing techniques. Nano-scratches were performed on plasma sprayed hydroxyapatite (HA) and HA-CNT coatings to quantify the adhesion of the osteoblast. The presence of CNTs in HA coating promotes an increase in the adhesion of osteoblasts. The adhesion force and energy of an osteoblast on a HA-CNT surface are 17 ± 2 µN/cell and 78 ± 14 pJ/cell respectively, as compared to 11 ± 2 µN/cell and 45 ± 10 pJ/cell on a HA surface after 1 day of incubation. The adhesion force and energy of the osteoblasts increase on both the surfaces with culture periods of up to 5 days. This increase is more pronounced for osteoblasts cultured on HA-CNT. Staining of actin filaments revealed a higher spreading and attachment of osteoblasts on a surface containing CNTs. The affinity of CNTs to conjugate with integrin and other proteins is responsible for the enhanced attachment of osteoblasts. Our results suggest that the addition of CNTs to surfaces used in medical applications may be beneficial when stronger adhesion of osteoblasts is desired.

  6. Development of dental composites with reactive fillers that promote precipitation of antibacterial-hydroxyapatite layers.

    PubMed

    Aljabo, Anas; Abou Neel, Ensanya A; Knowles, Jonathan C; Young, Anne M

    2016-03-01

    The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80 wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10 wt.% CHX and 0, 10, 20 or 40 wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4 weeks. XRD peak width and SEM images suggested this was due to the very small size (~10 nm) of the hydroxyapatite crystallites. Precipitate mass at 12 weeks was 22 wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7 wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1 week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12 weeks CHX formed 5 to 15% of the HA layer with 10 to 40 wt.% CaP respectively. Despite linear decline of strength and modulus in 4 weeks from 160 to 101 MPa and 4 to 2.4 GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively.

  7. Multilayered polymer microspheres by thermal imprinting during microsphere growth.

    PubMed

    Takekoh, Ryu; Li, Wen-Hui; Burke, Nicholas A D; Stöver, Harald D H

    2006-01-11

    Modulation of the polymerization temperature in precipitation polymerizations was used to form onion-type polymer microspheres consisting of multiple nested layers. Specifically, the copolymerization of chloromethylstyrene and divinylbenzene-55 in acetonitrile, at temperatures ramping between 65 and 75 degrees C, led to monodisperse, cross-linked microspheres of about 10 mum diameter that have radial density profiles closely reflecting the thermal profiles used. This thermal imprinting is attributed to the copolymer formed being close to its theta point during the polymerization. As the microspheres grow by continuously capturing oligomers from solution, the resulting transient surface gel layer expands and contracts with temperature, and thus records the reaction temperature profile in the form of a corresponding density profile, even as it cross-links.

  8. Synthesis and characterization of hydroxyapatite nanofiber by chemical precipitation method using surfactants

    SciTech Connect

    Gao, Shan; Sun, Kangning; Li, Aimin; Wang, Hongyou

    2013-03-15

    Highlights: ► We succeeded in synthesizing hydroxyapatite nano fibers by a chemical method. ► The reaction temperature is only 90 °C. ► The synthetic hydroxyapatite nano fiber is single crystal. - Abstract: We report a novel chemical precipitation route for the synthesis of hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, HA) fibers using surfactants as templates. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) reveal the characteristic peaks of HA. Transmission electron microscope (TEM) and high-resolution TEM revealed the nano structure, crystallinity and morphology of the HA fibers. The morphology of the HA fibers after calcinations were characterized by scanning electron microscope (SEM). Br{sup −} ions were quickly replaced by the excess PO{sub 4}{sup 3−} ions in the solution after the addition of cetyltrime-thylammonium bromide (CTAB). Meanwhile, CTAB formed a rod-like micelles. Precursors reacted with PO{sub 4}{sup 3−} at the surface of CTAB micelles and finally formed the nanofiber structure.

  9. Hydroxyapatite-hybridized chitosan/chitin whisker bionanocomposite fibers for bone tissue engineering applications.

    PubMed

    Pangon, Autchara; Saesoo, Somsak; Saengkrit, Nattika; Ruktanonchai, Uracha; Intasanta, Varol

    2016-06-25

    Biomimetic nanofibrous scaffolds derived from natural biopolymers for bone tissue engineering applications require good mechanical and biological performances including biomineralization. The present work proposes the utility of chitin whisker (CTWK) to enhance mechanical properties of chitosan/poly(vinyl alcohol) (CS/PVA) nanofibers and to offer osteoblast cell growth with hydroxyapatite (HA) mineralization. By using diacid as a solvent, electrospun CS/PVA nanofibrous membranes containing CTWK can be easily obtained. The dimension stability of nanofibrous CS/PVA/CTWK bionanocomposite is further controlled by exposing to glutaraldehyde vapor. The nanofibrous membranes obtained allow mineralization of HA in concentrated simulated body fluid resulting in an improvement of Young's modulus and tensile strength. The CTWK combined with HA in bionanocomposite is a key to promote osteoblast cell adhesion and proliferation. The present work, for the first time, demonstrates the use of CTWKs for bionanocomposite fibers of chitosan and its hydroxyapatite biomineralization with the function in osteoblast cell culture. These hydroxyapatite-hybridized CS/PVA/CTWK bionanocomposite fibers (CS/PVA/CTWK-HA) offer a great potential for bone tissue engineering applications.

  10. Mechanical, thermal, rheological and morphological behaviour of irradiated PP/HA composites

    NASA Astrophysics Data System (ADS)

    Ramírez, C.; Albano, C.; Karam, A.; Domínguez, N.; Sánchez, Y.; González, G.

    2005-07-01

    Hydroxyapatite (HA) reinforced polypropylene (PP) composites are being developed as bone graft materials. In this research, the effect of γ irradiation on mechanical, rheological, thermal and morphological behaviour of PP-HA composites was studied. The melt flow index of polymer increased markedly when it was exposed to radiation. This is indicative of chain scission reaction as the predominant process. During the tensile testing, the composites exhibited brittle behaviour, showing no fluency point. Elongation at break showed a tendency to decrease with the increase in radiation dose while stress at break did not show significant variation with radiation dose. High HA content (>20%) and radiation dose (25 kGy) had significant influence on thermal stability.

  11. Sulfobetaine as a zwitterionic mediator for 3D hydroxyapatite mineralization

    PubMed Central

    Liu, Pingsheng; Song, Jie

    2013-01-01

    Both positively and negatively charged residues play pivotal roles in recruiting precursor ions or ion clusters, and lowering interfacial energy in natural biomineralization process. Synergistic utilization of opposite charges, however, has rarely been implemented in the design of cytocompatible synthetic scaffolds promoting hydroxyapatite (HA)-mineralization and osteointegration. We report the use of cytocompatible zwitterionic sulfobetaine ligands to enable 3-dimensional in vitro mineralization of HA across covalently crosslinked hydrogels. The overall charge-neutral zwitterionic hydrogel effectively recruited oppositely charged precursor ions while overcame excessive swelling exhibited by anionic and cationic hydrogels under physiological conditions, resulting in denser and structurally well-integrated mineralized composites. Further controls over the size, content, and spatial distribution of the mineral domains within the zwitterionic hydrogel are accomplished by facile adjustments of hydrogel crosslinking densities and the supersaturation rate governing heterogeneous mineral nucleation and growth. These findings should inspire many creative uses of zwitterionic polymers and polymer coatings for skeletal tissue repair and regeneration. PMID:23332320

  12. Materials processing and in-vivo animal studies of nitrided hydroxyapatite bioceramics

    NASA Astrophysics Data System (ADS)

    Rashid, Nancy Elizabeth

    2000-10-01

    Calcium phosphate bioceramics are currently being used in medicine and dentistry, for reconstruction or repair of diseased or injured bone, but with limited success. Incorporating nitrogen into phosphate glasses has resulted in improved properties, and it is proposed that similar benefits may be gained from nitriding calcium phosphate bioceramics for bone implants as well. This work focuses on processing of hydroxyapatite and tricalcium phosphate bioceramics nitrided by using solid, liquid, gas and ion sources. These materials were characterized by chemical, structural, mechanical, and biological methods to determine both the material structure and their suitability as implant materials. Calcium nitride and NaPON glass were unsatisfactory sources of nitrogen for hydroxyapatite (HA) and/or tricalcium phosphate (TCP) ceramics. Calcium nitride, Ca3N2, is reacts with water vapor in the air, releasing ammonia, and leaving behind crystals of calcium oxide, CaO. The calcium oxide byproduct decreases the chemical stability of hydroxyapatite and HA/TCP composites in simulated body fluid. Sodium phosphorus oxynitride (NaPON) glass, in the form of a liquid sintering aid for HA, produces an inhomogeneous, composite as well. Hydroxyapatite heated at 800C in an ammonia atmosphere produces a homogeneous material with up to 2 wt% N. Infrared spectroscopy indicates cyanamide ions, CN22-, are formed by the incorporated nitrogen and impurity carbon. The use of 15N-doped ammonia results in an 15N NMR peak at 83.2 ppm, indicating P--N bonding. Raman spectroscopy may also indicate P--N bonding, but it is inconclusive. In a limited study, nitrogen may decrease the hardness and fracture toughness of the phosphate ceramic, hydroxyapatite, contrary to results expected for nitrogen in phosphate glasses. Nitrogen ions are incorporated in hydroxyapatite by ion implantation, with lower energies producing higher nitrogen contents. The highest concentration achieved was 3.55 wt% N, as determined

  13. Fabrication and characterization of plasma-sprayed HA/SiO(2) coatings for biomedical application.

    PubMed

    Morks, M F

    2008-01-01

    Fused silica powder has been mixed with hydroxyapatite (HA) powder and plasma sprayed by using gas tunnel-type plasma jet. The influence of silica content (10 wt% and 20 wt%) on the microstructure and mechanical properties of HA-silica coatings was investigated. For investigating the microstructure and mechanical properties of HA-silica coatings, SUS 304 stainless steel was used as substrate material. The spraying was carried out on roughened substrate in an atmospheric chamber. Scanning electron microscope micrographs of cross-sectioned HA/SiO(2) coatings showed that the sprayed HA coatings with 10 and 20 wt% SiO(2) have dense structure with low porosity compared to the pure HA coatings. On the other hand, as the amount of silica was increased the coatings became denser, harder and exhibited high abrasive wear resistance. The presence of silica significantly improved the adhesive strength of HA/SiO(2) coatings mainly due to the increase in bonding strength of the coating at the interface.

  14. Hydroxyapatite promotes superior keratocyte adhesion and proliferation in comparison with current keratoprosthesis skirt materials

    PubMed Central

    Mehta, J S; Futter, C E; Sandeman, S R; Faragher, R G A F; Hing, K A; Tanner, K E; Allan, B D S

    2005-01-01

    Aim: Published clinical series suggest the osteoodontokeratoprosthesis (OOKP) may have a lower extrusion rate than current synthetic keratoprostheses. The OOKP is anchored in the eye wall by autologous tooth. The authors’ aim was to compare adhesion, proliferation, and morphology for telomerase transformed keratocytes seeded on calcium hydroxyapatite (the principal mineral constituent of tooth) and materials used in the anchoring elements of commercially available synthetic keratoprostheses. Methods: Test materials were hydroxyapatite, polytetrafluoroethylene (PTFE), polyhydroxyethyl methacrylate (HEMA), and glass (control). Cell adhesion and viability were quantified at 4 hours, 24 hours, and 1 week using a calcein-AM/EthD-1 viability/cytotoxicity assay. Focal contact expression and cytoskeletal organisation were studied at 24 hours by confocal microscopy with immunoflourescent labelling. Further studies of cell morphology were performed using light and scanning electron microscopy. Results: Live cell counts were significantly greater on hydroxyapatite surfaces at each time point (p<0.04). Dead cell counts were significantly higher for PTFE at 7 days (p<0.002). ß1 integrin expression was highest on hydroxyapatite. Adhesion structures were well expressed in flat, spread out keratocytes on both HA and glass. Keratocytes tended to be thinner and spindle shaped on PTFE. The relatively few keratocytes visible on HEMA test surfaces were rounded and poorly adherent. Conclusions: Keratocyte adhesion, spreading, and viability on hydroxyapatite test surfaces is superior to that seen on PTFE and HEMA. Improving the initial cell adhesion environment in the skirt element of keratoprostheses may enhance tissue integration and reduce device failure rates. PMID:16170132

  15. Bone formation in a carbonate-substituted hydroxyapatite implant is inhibited by zoledronate: the importance of bioresorption to osteoconduction.

    PubMed

    Spence, G; Phillips, S; Campion, C; Brooks, R; Rushton, N

    2008-12-01

    Carbonate-substituted hydroxyapatite (CHA) is more osteoconductive and more resorbable than hydroxyapatite (HA), but the underlying mode of its action is unclear. We hypothesised that increased resorption of the ceramic by osteoclasts might subsequently upregulate osteoblasts by a coupling mechanism, and sought to test this in a large animal model. Defects were created in both the lateral femoral condyles of 12 adult sheep. Six were implanted with CHA granules bilaterally, and six with HA. Six of the animals in each group received the bisphosphonate zoledronate (0.05 mg/kg), which inhibits the function of osteoclasts, intra-operatively. After six weeks bony ingrowth was greater in the CHA implants than in HA, but not in the animals given zoledronate. Functional osteoclasts are necessary for the enhanced osteoconduction seen in CHA compared with HA.

  16. Pressureless sintering of dense hydroxyapatite-zirconia composites.

    PubMed

    Nayak, Y; Rana, R P; Pratihar, S K; Bhattacharyya, S

    2008-06-01

    Hydroxyapatite (HA)-TZP (2.5 mol% Y2O3) containing 2, 5, 7.5 and 10 wt% TZP were prepared using calcium nitrate, diammonium hydrogen orthophosphate, zirconium oxychloride and yttrium nitrate. The composite powder was prepared by a reverse strike precipitation method at a pH of 10.5. The precipitates after aging and washing were calcined at 850 degrees C to yield fine crystallites of HA and TZP. TEM study of the calcined powder revealed that while HA particles had both spherical and cuboidal morphology ( approximately 50-100 nm) the TZP particles were only of spherical nature ( approximately 50 nm). X-ray analysis showed that the calcined powder of all the four composition had only HA and t-ZrO2. Uniaxially compacted samples were sintered in air in the temperature range 1,150-1,250 degrees C. High sintered density (>95% of theoretical) was obtained for composites containing 2 and 5 wt% TZP, while it was 92% for 7.5 wt% and 90% for 10 wt% TZP compositions. X-ray analysis of sintered samples shows that with 2 wt% TZP, the retained phases were only HA and t-ZrO2. However, for 5, 7.5 and 10 wt% TZP addition both TCP and CaZrO3 were also observed along with HA and t-ZrO2. Bending strength was measured by three point bending as well by diametral compression test. While in three point bending, the highest strength was 72 MPa, it was 35.5 MPa for diametral compression. The strength shows a decreasing trend at higher ZrO2 content. SEM pictures show near uniform distribution of ZrO2 in HA matrix. The reduction in sintered density at higher ZrO2 content could be related to difference in the sintering behaviour of HA and ZrO2.

  17. Mechanisms of uranium interactions with hydroxyapatite: Implications for groundwater remediation

    USGS Publications Warehouse

    Fuller, C.C.; Bargar, J.R.; Davis, J.A.; Piana, M.J.

    2002-01-01

    The speciation of U(VI) sorbed to synthetic hydroxyapatite was investigated using a combination of U LIII-edge XAS, synchrotron XRD, batch uptake measurements, and SEM-EDS. The mechanisms of U(VI) removal by apatite were determined in order to evaluate the feasibility of apatitebased in-situ permeable reactive barriers (PRBs). In batch U(VI) uptake experiments with synthetic hydroxyapatite (HA), near complete removal of dissolved uranium (>99.5%) to <0.05 ??M was observed over a range of total U(VI) concentrations up to equimolar of the total P in the suspension. XRD and XAS analyses of U(VI)-reacted HA at sorbed concentrations ???4700 ppm U(VI) suggested that uranium(VI) phosphate, hydroxide, and carbonate solids were not present at these concentrations. Fits to EXAFS spectra indicate the presence of Ca neighbors at 3.81 A??. U-Ca separation, suggesting that U(VI) adsorbs to the HA surfaces as an inner-sphere complex. Uranium(VI) phosphate solid phases were not detected in HA with 4700 ppm sorbed U(VI) by backscatter SEM or EDS, in agreement with the surface complexation process. In contrast, U(VI) speciation in samples that exceeded 7000 ppm sorbed U(VI) included a crystalline uranium(VI) phosphate solid phase, identified as chernikovite by XRD. At these higher concentrations, a secondary, uranium(VI) phosphate solid was detected by SEM-EDS, consistent with chernikovite precipitation. Autunite formation occurred at total U:P molar ratios ???0.2. Our findings provide a basis for evaluating U(VI) sorption mechanisms by commercially available natural apatites for use in development of PRBs for groundwater U(VI) remediation.

  18. Degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid nanocomposite in simulated body fluid

    SciTech Connect

    Liuyun, Jiang; Chengdong, Xiong; Lixin, Jiang; Lijuan, Xu

    2013-10-15

    Graphical abstract: In this manuscript, we initiated a systematic study to investigate the effect of HA on thermal properties, inner structure, reduction of mechanical strength, surface morphology and the surface deposit of n-HA/PLGA composite with respect to the soaking time. The results showed that n-HA played an important role in improving the degradation behavior of n-HA/PLGA composite, which can accelerate the degradation of n-HA/PLGA composite and endow it with bioactivity, after n-HA was detached from PLGA during the degradation, so that n-HA/PLGA composite may have a more promising prospect of the clinical application than pure PLGA as bone fracture internal fixation materials, and the results would be of reference significance to predict the in vivo degradation and biological properties. - Highlights: • Effect of n-HA on degradation behavior of n-HA/PLGA composite was investigated. • Degradation behaviors of n-HA/PLGA and PLGA were carried out in SBF for 6 months. • Viscosity, thermal properties, inner structure and bending strength were tested. • n-HA can accelerate the degradation and endows it with bioactivity. - Abstract: To investigate the effect of hydroxyapatite(HA) on the degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid (HA/PLGA) nanocomposite, the degradation experiment of n-HA/PLGA composite and pure PLGA were carried out by soaking in simulated body fluid(SBF) at 37 °C for 1, 2, 4 and 6 months. The change of intrinsic viscosity, thermal properties, inner structure, bending strength reduction, surface morphology and the surface deposit of n-HA/PLGA composite and pure PLGA with respect to the soaking time were investigated by means of UbbeloHde Viscometer, differential scanning calorimeter (DSC), scanning electron microscope(SEM), electromechanical universal tester, a conventional camera and X-ray diffraction (XRD). The results showed that n-HA played an important role in improving the degradation behavior of n-HA

  19. Evaluation of the novel three-dimensional porous poly (L-lactic acid)/nano-hydroxyapatite composite scaffold.

    PubMed

    Huang, Jianghong; Xiong, Jianyi; Liu, Jianquan; Zhu, Weimin; Chen, Jielin; Duan, Li; Zhang, Jufeng; Wang, Daping

    2015-01-01

    To determine the optimal ratio of nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) in the novel three-dimensional porous PLLA/n-HA composite scaffolds, low-temperature rapid prototyping technology was employed to fabricate the composite materials with different n-HA contents. Mechanical properties and degradation behaviors of the composites were examined, and the scaffold microstructure and n-HA dispersion were observed by scanning electron microscope (SEM). Mechanical tests demonstrated that the tensile strength of the composite material gradually decreased with an increase in n-HA content. When the n-HA content reached 20 wt%, the bending strength of the composite material peaked at 138.5 MPa. SEM images demonstrated that the optimal content of n-HA was 20 wt% as the largest interconnected pore size that can be seen, with a porosity as high as 80%. In vitro degradation experiments demonstrated that the pH value of the material containing solution gradually decreased in a time-dependent manner, with a simultaneous weakening of the mechanical properties. In vitro study using rat osteoblast cells showed that the composite scaffolds were biocompatible; the 20 wt% n-HA scaffold offered particular improvement to rat osteoblast cell adhesion and proliferation compared to other compositions. It was therefore concluded that 20 wt% n-HA is the optimal nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) ratio, with promise for bone tissue engineering.

  20. Polarization Dependent Whispering Gallery Modes in Microspheres

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

    2016-01-01

    A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

  1. Modeling the Formation of Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    Pipes, R. B.; Weiser, E. S.; Gonsoulin, B.; Hubert, P.

    2002-01-01

    High temperature polyimide microspheres have been developed from polyimide solid residuum by a simple inflation process. Microspheres have been fabricated from several polyimide precursors through the use of a circulating air oven. Microsphere formation and final physical property characterization have been limited to simple mechanical and thermal testing. The present paper focuses on developing an understanding of microsphere formation through simple geometric rules for an incompressible polymeric material and microscopic observations of precursor residuum inflation. Inflation kinematics of the hollow polyimide microspheres as a function of time and temperature is discussed.

  2. Mesoporous Fe{sub 3}O{sub 4}/hydroxyapatite composite for targeted drug delivery

    SciTech Connect

    Gu, Lina; He, Xiaomei; Wu, Zhenyu

    2014-11-15

    Highlights: • Mesoporous Fe{sub 3}O{sub 4}/hydroxyapatite composite was synthesized by a simple, efficient and environmental friendly method. • The prepared material had a large surface area, high pore volume, and good magnetic separability. • DOX-loaded Fe{sub 3}O{sub 4}/hydroxyapatite composite exhibited surprising slow drug release behavior and pH-dependent behavior. - Abstract: In this contribution, we introduced a simple, efficient, and green method of preparing a mesoporous Fe{sub 3}O{sub 4}/hydroxyapatite (HA) composite. The as-prepared material had a large surface area, high pore volume, and good magnetic separability, which made it suitable for targeted drug delivery systems. The chemotherapeutic agent doxorubicin (DOX) was used to investigate the drug release behavior of Fe{sub 3}O{sub 4}/HA composite. The drug release profiles displayed a little burst effect and pH-dependent behavior. The release rate of DOX at pH 5.8 was larger than that at pH 7.4, which could be attributed to DOX protonation in acid medium. In addition, the released DOX concentrations remained at 0.83 and 1.39 μg/ml at pH 7.4 and 5.8, respectively, which indicated slow, steady, and safe release rates. Therefore, the as-prepared Fe{sub 3}O{sub 4}/hydroxyapatite composite could be an efficient platform for targeted anticancer drug delivery.

  3. Heat treatment's effects on hydroxyapatite powders in water vapor and air atmosphere

    NASA Astrophysics Data System (ADS)

    Karabulut, A.; Baştan, F. E.; Erdoǧan, G.; Üstel, F.

    2015-03-01

    Hydroxyapatite (HA; Ca10(PO4)6(OH)2) is the main chemical constituent of bone tissue (~70%) as well as HA which is a calcium phosphate based ceramic material forms inorganic tissue of bone and tooth as hard tissues is used in production of prosthesis for synthetic bone, fractured and broken bone restoration, coating of metallic biomaterials and dental applications because of its bio compatibility. It is known that Hydroxyapatite decomposes with high heat energy after heat treatment. Therefore hydroxyapatite powders that heated in water vapor will less decomposed phases and lower amorphous phase content than in air atmosphere. In this study high purity hydroxyapatite powders were heat treated with open atmosphere furnace and water vapor atmosphere with 900, 1000, 1200 °C. Morphology of same powder size used in this process by SEM analyzed. Chemical structures of synthesized coatings have been examined by XRD. The determination of particle size and morphological structure of has been characterized by Particle Sizer, and SEM analysis, respectively. Weight change of sample was recorded by thermogravimetric analysis (TGA) during heating and cooling.

  4. Affinity of the interface between hydroxyapatite (0001) and titanium (0001) surfaces: a first-principles investigation.

    PubMed

    Sun, Jin P; Dai, Jianhong; Song, Yan; Wang, You; Yang, Rui

    2014-12-10

    A basic understanding of the affinity between the hydroxyapatite (HA) and α-Ti surfaces is obtained through electronic structure calculations by first-principles method. The surface energies of HA(0001), HA (011̅0), HA (101̅1), and Ti(0001) surfaces have been calculated. The HA(0001) presents the most thermodynamically stable of HA. The HA/Ti interfaces were constructed by two kinds of interface models, the single interface (denoted as SI) and the double-interface (denoted as DI). Two methods, the full relaxation and the UBER, were applied to determine the interfacial separation and the atomic arrangement in the interfacial zone. The works of adhesion of interfaces with various stoichiometric HA surfaces were evaluated. For the HA(0001)/Ti(0001) interfaces, the work of adhesion is strongly dependent on the chemical environment of the HA surface. The values are -2.33, -1.52, and -0.80 J/m(2) for the none-, single-, and double-Ca terminated HA/Ti interfaces, respectively. The influence of atomic relaxation on the work of adhesion and interface separation is discussed. Full relaxation results include -1.99 J/m(2) work of adhesion and 0.220 nm separation between HA and Ti for the DI of 1-Ca-HA/Ti interface, while they are -1.14 J/m(2) and 0.235 nm by partial relaxation. Analysis of electronic structure reveals that charge transfer between HA and Ti slabs occurs during the formation of the HA/Ti interface. The transfer generates the Ti-O or Ti-Ca bonds across the interface and drives the HA/Ti interface system to metallic characteristic. The energetically favorable interfaces are formed when the outmost layer of HA comprises more O atoms at the interface.

  5. Synthesis and characterization of porous hydroxyapatite and hydroxyapatite coatings

    SciTech Connect

    Nieh, T G; Choi, B W; Jankowski, A F

    2000-10-25

    A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using water-soluble compounds and then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously reported. Resulting from the fact that the starting HAp powders were extremely fine, a relatively low activation energy for sintering was obtained. In the present study, both porous and dense structures were produced by varying powder morphology and sintering parameters. Porous structures consisting of open cells were constructed. Sintered structures were characterized using scanning electron microscopy and x-ray tomography. In the present paper, hydroxyapatite coatings produced by magnetron sputtering on silicon and titanium substrates will also be presented. The mechanical properties of the coatings were measured using nanoindentation techniques and microstructures examined using transmission electron microscopy.

  6. Production of monodisperse, polymeric microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Rhim, Won-Kyu (Inventor); Hyson, Michael T. (Inventor); Chang, Manchium (Inventor)

    1990-01-01

    Very small, individual polymeric microspheres with very precise size and a wide variation in monomer type and properties are produced by deploying a precisely formed liquid monomer droplet, suitably an acrylic compound such as hydroxyethyl methacrylate into a containerless environment. The droplet which assumes a spheroid shape is subjected to polymerizing radiation such as ultraviolet or gamma radiation as it travels through the environment. Polymeric microspheres having precise diameters varying no more than plus or minus 5 percent from an average size are recovered. Many types of fillers including magnetic fillers may be dispersed in the liquid droplet.

  7. Characterization of Multiwalled Carbon Nanotube-Reinforced Hydroxyapatite Composites Consolidated by Spark Plasma Sintering

    PubMed Central

    Kim, Duk-Yeon; Han, Young-Hwan; Lee, Jun Hee; Kang, Inn-Kyu; Jang, Byung-Koog; Kim, Sukyoung

    2014-01-01

    Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique. The relative density of pure HA increased with increasing sintering temperature, but that of the MWNT/HA composite reached almost full density at 900°C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature. Pull-out toughening of the MWNTs of the MWNT/HA composites was observed in the fractured surface, which can be used to predict the improvement of the mechanical properties. On the other hand, the existence of undispersed or agglomerate MWNTs in the MWNT/HA composites accompanied large pores. The formation of large pores increased with increasing sintering temperature and MWNT content. The addition of MWNT in HA increased the hardness and fracture toughness by approximately 3~4 times, despite the presence of large pores produced by un-dispersed MWNTs. This provides strong evidence as to why the MWNTs are good candidates as reinforcements for strengthening the ceramic matrix. The MWNT/HA composites did not decompose during SPS sintering. The MWNT-reinforced HA composites were non-toxic and showed a good cell affinity and morphology in vitro for 1 day. PMID:24724100

  8. Characterization of multiwalled carbon nanotube-reinforced hydroxyapatite composites consolidated by spark plasma sintering.

    PubMed

    Kim, Duk-Yeon; Han, Young-Hwan; Lee, Jun Hee; Kang, Inn-Kyu; Jang, Byung-Koog; Kim, Sukyoung

    2014-01-01

    Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique. The relative density of pure HA increased with increasing sintering temperature, but that of the MWNT/HA composite reached almost full density at 900°C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature. Pull-out toughening of the MWNTs of the MWNT/HA composites was observed in the fractured surface, which can be used to predict the improvement of the mechanical properties. On the other hand, the existence of undispersed or agglomerate MWNTs in the MWNT/HA composites accompanied large pores. The formation of large pores increased with increasing sintering temperature and MWNT content. The addition of MWNT in HA increased the hardness and fracture toughness by approximately 3~4 times, despite the presence of large pores produced by un-dispersed MWNTs. This provides strong evidence as to why the MWNTs are good candidates as reinforcements for strengthening the ceramic matrix. The MWNT/HA composites did not decompose during SPS sintering. The MWNT-reinforced HA composites were non-toxic and showed a good cell affinity and morphology in vitro for 1 day.

  9. In vitro bioactivity and cytocompatibility properties of spark plasma sintered HA-Ti composites.

    PubMed

    Kumar, Alok; Dhara, Sharmistha; Biswas, Krishanu; Basu, Bikramjit

    2013-02-01

    The present study reports the results of the detailed in vitro bioactivity and cytocompatibility properties of the hydroxyapatite (HA) and the HA-titanium (HA-Ti) composite with varying amount of Ti (5, 10, and 20 wt %), densified using spark plasma sintering process (SPS). Using this technique and tailoring suitable processing parameters, it has been possible to retain both HA and Ti in the sintered ceramics. Importantly, the uniquely designed SPS processing with suitably chosen parameters enables in achieving better mechanical properties, such as higher indentation fracture toughness (~1.5 MPa m(1/2) ) in HA-Ti composites compared with HA. X-ray diffraction and scanning electron microscopic (SEM) observations reveal good bioactivity of the HA-Ti composites with the formation of thick, flaky, and porous apatite layer when immersed in simulated body fluid at 37°C and pH of 7.4. Atomic absorption spectroscopic analysis of the simulated body fluid solution reveals dynamic changes in Ca(+2) ion concentration with more dissolution of Ca(+2) ion from the HA-20Ti composite. However, the measurements with inductively coupled plasma spectrometer do not record dissolution of Ti(+4) ions. Transmission electron microscopic analysis indicates weak crystalline nature of the apatite and confirms the formation of fine-scale apatite crystals. MTT assay, fluorescence, and SEM study demonstrate good cell viability and cell adhesion/proliferation of the Saos -2 cells, cultured on the developed composites under standard culture condition, and the difference in cell viability has been discussed in reference to substrate composition and roughness. Overall, HA-Ti composites exhibit comparable and even better in vitro bioactivity and cytocompatibility properties than HA.

  10. Hydroxyapatite coatings on nanotubular titanium dioxide thin films prepared by radio frequency magnetron sputtering.

    PubMed

    Shin, Jinho; Lee, Kwangmin; Koh, Jeongtae; Son, Hyeju; Kim, Hyunseung; Lim, Hyun-Pil; Yun, Kwidug; Oh, Gyejeong; Lee, Seokwoo; Oh, Heekyun; Lee, Kyungku; Hwang, Gabwoon; Park, Sang-Won

    2013-08-01

    In this study, hydroxyapatite (HA) was coated on anodized titanium (Ti) surfaces through radio frequency magnetron sputtering in order to improve biological response of the titanium surface. All the samples were blasted with resorbable blasting media (RBM). RBM-blasted Ti surface, anodized Ti surface, as-sputtered HA coating on the anodized Ti surface, and heat-treated HA coating on the anodized Ti surface were prepared. The samples were characterized using scanning electron microscopy and X-ray photoemission spectroscopy, and biologic responses were evaluated. The top of the TiO2 nanotubes was not closed by HA particles when the coating time is less than 15 minutes. It was demonstrated that the heat-treated HA was well-crystallized and this enhanced the cell attachment of the anodized Ti surface.

  11. A study on the grafting reaction of isocyanates with hydroxyapatite particles.

    PubMed

    Liu, Q; de Wijn, J R; van Blitterswijk, C A

    1998-06-05

    The surface grafting reactions of a series of isocyanates with hydroxyapatite particles at different temperatures were studied by Infrared spectrophotometry (IR) and thermal gravimetric analysis (TGA). The study results show that both hexamethylene diisocyanate (HMDI) and isocyanatoethyl methacrylate (ICEM) react readily with HA while ethyl isocyanate acetate (EIA) and butyl isocyanate (BIC) have lower reactivity towards HA particles. It also has been found that the reaction of ICEM with HA follows a second-order reaction mechanism, despite the heterogeneous nature of the reaction, while the reaction of HMDI with HA does not due to the complexity of the reaction. Based on this study, it is concluded that ICEM and HMDI are suitable agents for the coupling of polymers due to their reactivity towards HA.

  12. Electrospun polyvinyl alcohol-collagen-hydroxyapatite nanofibers: a biomimetic extracellular matrix for osteoblastic cells

    NASA Astrophysics Data System (ADS)

    Song, Wei; Markel, David C.; Wang, Sunxi; Shi, Tong; Mao, Guangzhao; Ren, Weiping

    2012-03-01

    The failure of prosthesis after total joint replacement is due to the lack of early implant osseointegration. In this study polyvinyl alcohol-collagen-hydroxyapatite (PVA-Col-HA) electrospun nanofibrous meshes were fabricated as a biomimetic bone-like extracellular matrix for the modification of orthopedic prosthetic surfaces. In order to reinforce the PVA nanofibers, HA nanorods and Type I collagen were incorporated into the nanofibers. We investigated the morphology, biodegradability, mechanical properties and biocompatibility of the prepared nanofibers. Our results showed these inorganic-organic blended nanofibers to be degradable in vitro. The encapsulated nano-HA and collagen interacted with the PVA content, reinforcing the hydrolytic resistance and mechanical properties of nanofibers that provided longer lasting stability. The encapsulated nano-HA and collagen also enhanced the adhesion and proliferation of murine bone cells (MC3T3) in vitro. We propose the PVA-Col-HA nanofibers might be promising modifying materials on implant surfaces for orthopedic applications.

  13. Production of hydroxyapatite layers on the plasma electrolytically oxidized surface of titanium alloys.

    PubMed

    Lugovskoy, Alex; Lugovskoy, Svetlana

    2014-10-01

    Hydroxyapatite (HA) is a bioactive material that is widely used for improving the osseointegration of titanium dental implants. Titanium can be coated with HA by various methods, such as chemical vapor deposition (CVD), thermal spray, or plasma spray. HA coatings can also be grown on titanium surfaces by hydrothermal, chemical, and electrochemical methods. Plasma electrolytic oxidation (PEO), or microarc oxidation (MAO), is an electrochemical method that enables the production of a thick porous oxide layer on the surface of a titanium implant. If the electrolyte in which PEO is performed contains calcium and phosphate ions, the oxide layer produced may contain hydroxyapatite. The HA content can then be increased by subsequent hydrothermal treatment. The HA thus produced on titanium surfaces has attractive properties, such as a high porosity, a controllable thickness, and a considerable density, which favor its use in dental and bone surgery. This review summarizes the state of the art and possible further development of PEO for the production of HA on Ti implants.

  14. Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

    PubMed Central

    Demnati, Imane; Grossin, David; Marsan, Olivier; Bertrand, Ghislaine; Collonges, Gérard; Combes, Christèle; Parco, Maria; Braceras, Inigo; Alexis, Joel; Balcaen, Yannick; Rey, Christian

    2015-01-01

    Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities. PMID:25893015

  15. Development of porous polyurethane/strontium-substituted hydroxyapatite composites for bone regeneration.

    PubMed

    Sariibrahimoglu, Kemal; Yang, Wanxun; Leeuwenburgh, Sander C G; Yang, Fang; Wolke, Joop G C; Zuo, Yi; Li, Yubao; Jansen, John A

    2015-06-01

    Polyurethane (PU) has been widely used for the biomedical applications but its potential for bone regeneration is limited due to its lack of osteoconductive properties. Strontium substituted hydroxyapatite (SrHA) particles, on the other hand, are known to exhibit a positive effect on bone formation. Therefore, the aim of this study was to (i) develop porous polyurethane scaffolds containing strontium SrHA nanoparticles (PU/SrHA) and (ii) compare their in vitro biological performance for applications in bone regeneration to PU scaffolds. SrHA and HA was synthesized using a conventional wet-chemical neutralization reaction at temperatures of 25, 50, and 80°C. Chemical analysis was performed by inductively coupled plasma-optical emission spectrometry. Synthesizing temperatures at 25 and at 50°C were selected for the composite preparation (abbreviated as HA-25, SrHA-25, HA-50, and SrHA-50, respectively). PU was synthesized from isophorone diisocyanate, polytetramethylene ether glycol, and 1,4-butanediol. Composite scaffolds were prepared by addition of HA or SrHA nanoparticles into PU scaffolds during polymer preparation. The results showed that the Sr content in HA nanoparticles increased with increasing synthesis temperature. The addition of nanoparticles decreased the elongation-at-break and tensile strength, but significantly increased the surface wettability of the PU scaffolds. In vitro degradation tests demonstrated that release of cations was significantly higher from PU/SrHA-50 composite scaffolds. Cell culture tests indicated that PU composites containing either HA or SrHA nanoparticles increased proliferation of bone marrow stem cells as compared to plain PU scaffolds, whereas osteogenic differentiation was not affected by the incorporation of HA nanoparticles irrespective of the incorporation of Sr.

  16. The enamel protein amelotin is a promoter of hydroxyapatite mineralization.

    PubMed

    Abbarin, Nastaran; San Miguel, Symone; Holcroft, James; Iwasaki, Kengo; Ganss, Bernhard

    2015-05-01

    Amelotin (AMTN) is a recently discovered protein that is specifically expressed during the maturation stage of dental enamel formation. It is localized at the interface between the enamel surface and the apical surface of ameloblasts. AMTN knock-out mice have hypomineralized enamel, whereas transgenic mice overexpressing AMTN have a compact but disorganized enamel hydroxyapatite (HA) microstructure, indicating a possible involvement of AMTN in regulating HA mineralization directly. In this study, we demonstrated that recombinant human (rh) AMTN dissolved in a metastable buffer system, based on light scattering measurements, promotes HA precipitation. The mineral precipitates were characterized by scanning and transmission electron microscopy and electron diffraction. Colloidal gold immunolabeling of AMTN in the mineral deposits showed that protein molecules were associated with HA crystals. The binding affinity of rh-AMTN to HA was found to be comparable to that of amelogenin, the major protein of the forming enamel matrix. Overexpression of AMTN in mouse calvaria cells also increased the formation of calcium deposits in the culture medium. Overexpression of AMTN during the secretory stage of enamel formation in vivo resulted in rapid and uncontrolled enamel mineralization. Site-specific mutagenesis of the potential serine phosphorylation motif SSEEL reduced the in vitro mineral precipitation to less than 25%, revealing that this motif is important for the HA mineralizing function of the protein. A synthetic short peptide containing the SSEEL motif was only able to facilitate mineralization in its phosphorylated form ((P)S(P) SEEL), indicating that this motif is necessary but not sufficient for the mineralizing properties of AMTN. These findings demonstrate that AMTN has a direct influence on biomineralization by promoting HA mineralization and suggest a critical role for AMTN in the formation of the compact aprismatic enamel surface layer during the maturation

  17. Electrochemical synthesis of nanosized hydroxyapatite by pulsed direct current method

    SciTech Connect

    Nur, Adrian; Rahmawati, Alifah; Ilmi, Noor Izzati; Affandi, Samsudin; Widjaja, Arief

    2014-02-24

    Synthesis of nanosized of hydroxyapatite (HA) by electrochemical pulsed direct current (PDC) method has been studied. The aim of this work is to study the influence of various PDC parameters (pH initial, electrode distance, duty cycle, frequency, and amplitude) on particle surface area of HA powders. The electrochemical synthesis was prepared in solution Ca{sup 2+}/EDTA{sup 4−}/PO{sub 4}{sup 3+} at concentration 0.25/0.25/0.15 M for 24 h. The electrochemical cell was consisted of two carbon rectangular electrodes connected to a function generator to produce PDC. There were two treatments for particles after electrosynthesized, namely without aging and aged for 2 days at 40 °C. For both cases, the particles were filtered and washed by demineralized water to eliminate the impurities and unreacted reactants. Then, the particles were dried at 100 °C for 2 days. The dried particles were characterized by X-ray diffraction, surface area analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectra and thermogravimetric and differential thermal analysis. HA particles can be produced when the initial pH > 6. The aging process has significant effect on the produced HA particles. SEM images of HA particles showed that the powders consisted of agglomerates composed of fine crystallites and have morphology plate-like and sphere. The surface area of HA particles is in the range of 25 – 91 m{sup 2}/g. The largest particle surface area of HA was produced at 4 cm electrode distance, 80% cycle duty, frequency 0.1 Hz, amplitude 9 V and with aging process.

  18. Nanostructuring and texturing of pulsed laser deposited hydroxyapatite thin films

    NASA Astrophysics Data System (ADS)

    Kim, Hyunbin; Catledge, Shane; Vohra, Yogesh; Camata, Renato; Lacefield, William

    2003-03-01

    Hydroxyapatite (HA) [Ca_10(PO_4)_6(OH)_2] is commonly deposited onto orthopedic and dental metallic implants to speed up bone formation around devices, allowing earlier stabilization in a patient. Pulsed laser deposition (PLD) is a suitable means of placing thin HA films on these implants because of its control over stoichiometry, crystallinity, and nanostructure. These characteristics determine the mechanical properties of the films that must be optimized to improve the performance of load-bearing implants and other devices that undergo bone insertion. We have used PLD to produce nanostructured and preferentially oriented HA films and evaluated their mechanical properties. Pure, highly crystalline HA films on Ti-6Al-4V substrates were obtained using a KrF excimer laser (248nm) with energy density of 4-8 J/cm^2 and deposition temperature of 500-700^rcC. Scanning electron and atomic force microscopies reveal that our careful manipulation of energy density and substrate temperature has led to films made up of HA grains in the nanometer scale. Broadening of x-ray diffraction peaks as a function of deposition temperature suggests it may be possible to control the film nanostructure to a great extent. X-ray diffraction also shows that as the laser energy density is increased in the 4-8 J/cm^2 range, the hexagonal HA films become preferentially oriented along the c-axis perpendicular to the substrate. Texture, nanostructure, and phase make-up all significantly influence the mechanical properties. We will discuss how each of these factors affects hardness and Young's modulus of the HA films as measured by nanoindentation.

  19. PLLA-HA composites: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gema; Albano, Carmen; Palacios, Jordana

    2012-07-01

    A composite based on PLLA -HA was prepared by the solvent casting technique and characterized. An interaction between the polymer matrix and HA through the carbonyl and phosphate groups was obtained by FTIR . The several thermal transitions of PLLA were evaluated by DSC: the glass transition, crystallization, cold crystallization, melt-recrystallization and melting. The addition of HA to PLLA matrix increases its glass transition temperature and no major changes on the melting temperature and crystallinity were observed. The PLLA-HA composite showed better thermal stability than the neat polymer. The introduction of the nano-HA particles increased the decomposition temperature and the activation energy retarding the decomposition process.

  20. Processing and mechanical behavior of lamellar structured degradable magnesium-hydroxyapatite implants.

    PubMed

    Ratna Sunil, B; Ganapathy, C; Sampath Kumar, T S; Chakkingal, Uday

    2014-12-01

    Multilayered (laminated) composites exhibit tunable mechanical behavior compared to bulk materials due to the presence of more interfaces and therefore magnesium based composites are gaining wide popularity as biodegradable materials targeted for temporary implant applications. The objective of the present work is to fabricate magnesium based lamellar metal matrix composites (MMCs) for degradable implant applications. Nano-hydroxyapatite (HA) powder was selected as the secondary phase and lamellar structured magnesium-nano-hydroxyapatite (Mg-HA) composites of 8, 10 and 15wt% HA were fabricated by ball milling and spark plasma sintering. It was found that HA particles were coated on the Mg flakes after 20h of ball milling carried out using tungsten carbide (WC) as the milling media. Spark plasma sintering of the milled powders resulted in the formation of lamellar structure of Mg with the presence of HA and magnesium oxide (MgO) at the inter-lamellar sites of the composites. Phase analysis of the milled powder by an X-ray diffraction (XRD) method confirms the presence of HA and MgO along with Mg after sintering. Corrosion behavior of the composites investigated by potentiodynamic polarization tests shows a reduction in the inter-lamellar corrosion with increase in HA content and the best corrosion resistance is found for the Mg-10% HA composite. This composite also exhibits maximum Vickers hardness. Young׳s modulus and fracture toughness measured by nano-indentation method were higher for the Mg-8% HA composite. The results thus suggest that lamellar structured Mg composites with 8% and 10% HA show promise for temporary degradable orthopedic implant applications because of their improved corrosion resistance and superior mechanical properties.

  1. Preparation and properties of in-situ growth of carbon nanotubes reinforced hydroxyapatite coating for carbon/carbon composites.

    PubMed

    Liu, Shoujie; Li, Hejun; Su, Yangyang; Guo, Qian; Zhang, Leilei

    2017-01-01

    Carbon nanotubes (CNTs) possess excellent mechanical properties for their role playing in reinforcement as imparting strength to brittle hydroxyapatite (HA) bioceramic coating. However, there are few reports relating to the in-situ grown carbon nanotubes reinforced hydroxyapatite (CNTs-HA) coating. Here we demonstrate the potential application in reinforcing biomaterials by an attempt to use in-situ grown of CNTs strengthen HA coating, using a combined method composited of injection chemical vapor deposition (ICVD) and pulsed electrodeposition. The microstructure, phases and chemical compositions of CNTs-HA coatings were characterized by various advanced methods. The scanning electron microscopy (SEM) images indicated that CNTs-HA coatings avoided the inhomogeneous dispersion of CNTs inside HA coating. The result show that the interfacial shear strength between CNTs-HA coating and the C/C composite matrix reaches to 12.86±1.43MPa. Potenitodynamic polarization and electrochemical impedance spectroscopy (EIS) studies show that the content of CNTs affects the corrosion resistance of CNTs-HA coating. Cell culturing and simulated body fluid test elicit the biocompatibility with living cells and bioactivity of CNTs-HA coatings, respectively.

  2. Development of Risperidone PLGA Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2014-01-01

    The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25) were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug. PMID:24616812

  3. Microspheres and nanoparticles from ultrasound

    NASA Astrophysics Data System (ADS)

    Suh, Won Hyuk

    Improved preparations of various examples of monodispersed, porous, hollow, and core-shell metal and semiconductor nanoparticles or nanowires have been developed. Now titania microspheres and nanoparticles and silica microspheres can be synthesized using an inexpensive high frequency (1.7 MHz) ultrasonic generator (household humidifier; ultrasonic spray pyrolysis; USP). Morphology and pore size of titania microspheres were controlled by the silica to Ti(IV) ratio and silica particle size. Fine tuning the precursor ratio affords sub-50 nm titania nanoparticles as well. In terms of silica microspheres, morphology was controlled by the silica to organic monomer ratio. In liquids irradiated with high intensity ultrasound (20 kHz; HIUS), acoustic cavitation produces high energy chemistry through intense local heating inside the gas phase of collapsing bubbles in the liquid. HIUS and USP confine the chemical reactions to isolated sub-micron reaction zones, but sonochemistry does so in a heated gas phase within a liquid, while USP uses a hot liquid droplet carried by a gas flow. Thus, USP can be viewed as a method of phase-separated synthesis using submicron-sized droplets as isolated chemical reactors for nanomaterial synthesis. While USP has been used to create both titania and silica spheres separately, there are no prior reports of titania-silica composites. Such nanocomposites of metal oxides have been produced, and by further manipulation, various porous structures with fascinating morphologies were generated. Briefly, a precursor solution was nebulized using a commercially available household ultrasonic humidifier (1.7 MHz ultrasound generator), and the resulting mist was carried in a gas stream of air through a quartz glass tube in a hot furnace. After exiting the hot zone, these microspheres are porous or hollow and in certain cases magnetically responsive. In the case of titania microspheres, they are rapidly taken up into the cytoplasm of mammalian cells and

  4. Development and Characterization of Biphasic Hydroxyapatite/β-TCP Cements.

    PubMed

    Gallinetti, Sara; Canal, Cristina; Ginebra, Maria-Pau; Ferreira, J

    2014-04-01

    Biphasic calcium phosphate bioceramics composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have relevant properties as synthetic bone grafts, such as tunable resorption, bioactivity, and intrinsic osteoinduction. However, they have some limitations associated to their condition of high-temperature ceramics. In this work self-setting Biphasic Calcium Phosphate Cements (BCPCs) with different HA/β-TCP ratios were obtained from self-setting α-TCP/β-TCP pastes. The strategy used allowed synthesizing BCPCs with modulated composition, compressive strength, and specific surface area. Due to its higher solubility, α-TCP was fully hydrolyzed to a calcium-deficient HA (CDHA), whereas β-TCP remained unreacted and completely embedded in the CDHA matrix. Increasing amounts of the non-reacting β-TCP phase resulted in a linear decrease of the compressive strength, in association to the decreasing amount of precipitated HA crystals, which are responsible for the mechanical consolidation of apatitic cements. Ca(2+) release and degradation in acidic medium was similar in all the BCPCs within the timeframe studied, although differences might be expected in longer term studies once β-TCP, the more soluble phase was exposed to the surrounding media.

  5. A functional agarose-hydroxyapatite scaffold for osteochondral interface regeneration

    PubMed Central

    Khanarian, Nora T.; Haney, Nora M.; Burga, Rachel A.; Lu, Helen H.

    2013-01-01

    Regeneration of the osteochondral interface is critical for integrative and functional cartilage repair. This study focuses on the design and optimization of a hydrogel-ceramic composite scaffold of agarose and hydroxyapatite (HA) for calcified cartilage formation. The first study objective was to compare the effects of HA on non-hypertrophic and hypertrophic chondrocytes cultured in the composite scaffold. Specifically, cell growth, biosynthesis, hypertrophy, and scaffold mechanical properties were evaluated. Next, the ceramic phase of the scaffold was optimized in terms of particle size (200 nm vs. 25 µm) and dose (0–6 w/v%). It was observed that while deep zone chondrocyte (DZC) biosynthesis and hypertrophy remained unaffected, hypertrophic chondrocytes measured higher matrix deposition and mineralization potential with the addition of HA. Most importantly, higher matrix content translated into significant increases in both compressive and shear mechanical properties. While cell hypertrophy was independent of ceramic size, matrix deposition was higher only with the addition of micron-sized ceramic particles. In addition, the highest matrix content, mechanical properties and mineralization potential were found in scaffolds with 3% micro-HA, which approximates both the mineral aggregate size and content of the native interface. These results demonstrate that the biomimetic hydrogel-ceramic composite is optimal for calcified cartilage formation and is a promising design strategy for osteochondral interface regeneration. PMID:22531222

  6. Hydroxyapatite Formation on a Novel Dental Cement in Human Saliva

    PubMed Central

    Engstrand, Johanna; Unosson, Erik; Engqvist, Håkan

    2012-01-01

    Dental materials have to meet high standards regarding mechanical strength and handling properties. There is however only a limited amount of research that has been devoted to natural formation of hydroxyapatite (HA) in contact with the materials. The objective of the current investigation was to study the surface reactions occurring in human salvia on a novel dental cement. Ceramir Crown & Bridge, a bioceramic luting agent intended for permanent cementation of conventional oral prosthetics, was evaluated by immersing discs made from the cement in human saliva and phosphate buffered saline (PBS) for seven days, after which they were dried and analyzed. The analytical methods used in order to verify HA formation on the surface were grazing incidence X-ray diffraction (GI-XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All results showed that HA was formed on the surfaces of samples stored in saliva as well as on samples stored in PBS. The possibility of a dental luting cement to promote natural formation of HA at the tooth interface increases the stability and durability of the system and could help prevent secondary caries. PMID:23056955

  7. Injectable PLGA microsphere/calcium phosphate cements: physical properties and degradation characteristics.

    PubMed

    Habraken, W J E M; Wolke, J G C; Mikos, A G; Jansen, J A

    2006-01-01

    Calcium phosphate (CaP) cements show an excellent biocompatibility and often have a high mechanical strength, but in general degrade relatively slow. To increase degradation rates, macropores can be introduced into the cement, e.g., by the inclusion of biodegradable microspheres into the cement. The aim of this research is to develop an injectable PLGA microsphere/CaP cement with sufficient setting/cohesive properties and good mechanical and physical properties. PLGA microspheres were prepared using a water-in-oil-in-water double-emulsion technique. The CaP-cement used was Calcibon, a commercially available hydroxyapatite-based cement. 10:90 and 20:80 dry wt% PLGA microsphere/CaP cylindrical scaffolds were prepared as well as microporous cement (reference material). Injectability, setting time, cohesive properties and porosity were determined. Also, a 12-week degradation study in PBS (37 degree C) was performed. Results showed that injectability decreased with an increase in PLGA microsphere content. Initial and final setting time of the PLGA/CaP samples was higher than the microporous sample. Porosity of the different formulations was 40.8% (microporous), 60.2% (10:90) and 69.3% (20:80). The degradation study showed distinct mass loss and a pH decrease of the surrounding medium starting from week 6 with the 10:90 and 20:80 formulations, indicating PLGA erosion. Compression strength of the PLGA microsphere/CaP samples decreased siginificantly in time, the microporous sample remained constant. After 12 weeks both PLGA/CaP samples showed a structure of spherical micropores and had a compressive strength of 12.2 MPa (10:90) and 4.3 MPa (20:80). Signs of cement degradation were also found with the 20:80 formulation. In conclusion, all physical parameters were well within workable ranges with both 10:90 and 20:80 PLGA microsphere/CaP cements. After 12 weeks the PLGA was totally degraded and a highly porous, but strong scaffold remained.

  8. Template synthesis of ordered macroporous hydroxyapatite bioceramics.

    PubMed

    Ji, Lijun; Jell, Gavin; Dong, Yixiang; Jones, Julian R; Stevens, Molly M

    2011-08-28

    Hydroxyapatite has found wide application in bone tissue engineering. Here we use a macroporous carbon template to generate highly ordered macroporous hydroxyapatite bioceramics composed of close-packed hollow spherical pores with interconnected channels. The template has advantages for the preparation of ordered materials.

  9. Nanostructure of biocompatible titania/hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Fomin, Aleksandr A.; Rodionov, Igor V.; Steinhauer, Aleksey B.; Fomina, Marina A.; Petrova, Natalia V.; Zakharevich, Andrey M.; Skaptsov, Aleksandr A.; Gribov, Andrey N.; Atkin, Vsevolod S.

    2014-01-01

    The article describes prospective composite biocompatible titania coatings modified with hydroxyapatite nanoparticles and obtained on intraosseous implants fabricated from commercially pure titanium VT1-00. Consistency changes of morphological characteristics, crystalline structure, physical and mechanical properties and biocompatibility of experimental titanium implant coatings obtained by the combination of oxidation and surface modification with hydroxyapatite during induction heat treatment are defined.

  10. Structural analysis of hydroxyapatite coatings on titanium.

    PubMed

    Ducheyne, P; Van Raemdonck, W; Heughebaert, J C; Heughebaert, M

    1986-03-01

    Hydroxyapatite from two sources was electrophoretically deposited onto flat titanium plate material. Depending upon the deposition conditions various changes in the structure of the ceramic were identified. A well-adhering Ti-P compound was present at the interface. Hydroxyapatite oxygenated to various degrees and tetracalcium phosphate were reproducibly formed in the coating.

  11. Remineralization potential of nano-hydroxyapatite on initial enamel lesions: an in vitro study.

    PubMed

    Huang, S; Gao, S; Cheng, L; Yu, H

    2011-01-01

    The application of nano-hydroxyapatite (HA) in the repair of early caries lesion has received considerable attention. Neither the effects of the size of HA nor the effects of the effective pH range of nano-HA on remineralization have been investigated comprehensively, and the protective mechanism is still open for debate. To address these factors, the remineralization effect of nano-HA on demineralized bovine enamel is investigated under pH cycling conditions through surface and cross-sectional microhardness (CSMH) tests and polarized light microscopy (PLM). The percentage of surface microhardness recovery and integrated mineral loss obtained from CSMH tests demonstrated that nano-HA provides better remineralization than micro-HA. However, detailed investigation using CSMH tests and PLM indicated that nano-HA helped mineral deposition predominantly in the outer layer of the lesion and only had a limited capacity to reduce lesion depth. Nevertheless, the remineralization effect of nano-HA increased significantly when the pH was less than 7.0. Clearly, nano-HA has potential as an effective repair material and anticaries agent. Our findings also suggest that both the particle- and ion-mediated remineralization pathways in nano-HA may contribute to the repair of demineralized enamel.

  12. Effects of zinc-substituted nano-hydroxyapatite coatings on bone integration with implant surfaces*

    PubMed Central

    Zhao, Shi-fang; Dong, Wen-jing; Jiang, Qiao-hong; He, Fu-ming; Wang, Xiao-xiang; Yang, Guo-li

    2013-01-01

    Objective: The purpose of this study was to investigate the effects of a zinc-substituted nano-hydroxyapatite (Zn-HA) coating, applied by an electrochemical process, on implant osseointegraton in a rabbit model. Methods: A Zn-HA coating or an HA coating was deposited using an electrochemical process. Surface morphology was examined using field-emission scanning electron microscopy. The crystal structure and chemical composition of the coatings were examined using an X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). A total of 78 implants were inserted into femurs and tibias of rabbits. After two, four, and eight weeks, femurs and tibias were retrieved and prepared for histomorphometric evaluation and removal torque (RTQ) tests. Results: Rod-like HA crystals appeared on both implant surfaces. The dimensions of the Zn-HA crystals seemed to be smaller than those of HA. XRD patterns showed that the peaks of both coatings matched well with standard HA patterns. FTIR spectra showed that both coatings consisted of HA crystals. The Zn-HA coating significantly improved the bone area within all threads after four and eight weeks (P<0.05), the bone to implant contact (BIC) at four weeks (P<0.05), and RTQ values after four and eight weeks (P<0.05). Conclusions: The study showed that an electrochemically deposited Zn-HA coating has potential for improving bone integration with an implant surface. PMID:23733429

  13. Biomimetic helical rosette nanotubes and nanocrystalline hydroxyapatite coatings on titanium for improving orthopedic implants.

    PubMed

    Zhang, Lijie; Chen, Yupeng; Rodriguez, Jose; Fenniri, Hicham; Webster, Thomas J

    2008-01-01

    Natural bone consists of hard nanostructured hydroxyapatite (HA) in a nanostructured protein-based soft hydrogel template (ie, mostly collagen). For this reason, nanostructured HA has been an intriguing coating material on traditionally used titanium for improving orthopedic applications. In addition, helical rosette nanotubes (HRNs), newly developed materials which form through the self-assembly process of DNA base pair building blocks in body solutions, are soft nanotubes with a helical architecture that mimics natural collagen. Thus, the objective of this in vitro study was for the first time to combine the promising attributes of HRNs and nanocrystalline HA on titanium and assess osteoblast (bone-forming cell) functions. Different sizes of nanocrystalline HA were synthesized in this study through a wet chemical precipitation process following either hydrothermal treatment or sintering. Transmission electron microscopy images showed that HRNs aligned with nanocrystalline HA, which indicates a high affinity between both components. Some of the nanocrystalline HA formed dense coatings with HRNs on titanium. More importantly, results demonstrated enhanced osteoblast adhesion on the HRN/nanocrystalline HA-coated titanium compared with conventional uncoated titanium. Among all the HRN/nanocrystalline HA coatings tested, osteoblast adhesion was the greatest when HA nanometer particle size was the smallest. In this manner, this study demonstrated for the first time that biomimetic HRN/nanocrystalline HA coatings on titanium were cytocompatible for osteoblasts and, thus, should be further studied for improving orthopedic implants.

  14. An amphiphilic degradable polymer/hydroxyapatite composite with enhanced handling characteristics promotes osteogenic gene expression in bone marrow stromal cells.

    PubMed

    Kutikov, Artem B; Song, Jie

    2013-09-01

    Electrospun polymer/hydroxyapatite (HA) composites combining biodegradability with osteoconductivity are attractive for skeletal tissue engineering applications. However, most biodegradable polymers such as poly(lactic acid) (PLA) are hydrophobic and do not blend with adequate interfacial adhesion with HA, compromising the structural homogeneity, mechanical integrity and biological performance of the composite. To overcome this challenge, we combined a hydrophilic polyethylene glycol (PEG) block with poly(d,l-lactic acid) to improve the adhesion of the degradable polymer with HA. The amphiphilic triblock copolymer PLA-PEG-PLA (PELA) improved the stability of HA-PELA suspension at 25wt.% HA content, which was readily electrospun into HA-PELA composite scaffolds with uniform fiber dimensions. HA-PELA was highly extensible (failure strain>200% vs. <40% for HA-PLA), superhydrophilic (∼0° water contact angle vs. >100° for HA-PLA), and exhibited an 8-fold storage modulus increase (unlike deterioration for HA-PLA) upon hydration, owing to the favorable interaction between HA and PEG. HA-PELA also better promoted osteochondral lineage commitment of bone marrow stromal cells in unstimulated culture and supported far more potent osteogenic gene expression upon induction than HA-PLA. We demonstrate that the chemical incorporation of PEG is an effective strategy to improve the performance of degradable polymer/HA composites for bone tissue engineering applications.

  15. Effect of cell-seeded hydroxyapatite scaffolds on rabbit radius bone regeneration.

    PubMed

    Rathbone, C R; Guda, T; Singleton, B M; Oh, D S; Appleford, M R; Ong, J L; Wenke, J C

    2014-05-01

    Highly porous hydroxyapatite (HA) scaffolds were developed as bone graft substitutes using a template coating process, characterized, and seeded with bone marrow-derived mesenchymal stem cells (BMSCs). To test the hypothesis that cell-seeded HA scaffolds improve bone regeneration, HA scaffolds without cell seeding (HA-empty), HA scaffolds with 1.5 × 10(4) BMSCs (HA-low), and HA scaffolds with 1.5 × 10(6) BMSCs (HA-high) were implanted in a 10-mm rabbit radius segmental defect model for 4 and 8 weeks. Three different fluorochromes were administered at 2, 4, and 6 weeks after implantation to identify differences in temporal bone growth patterns. It was observed from fluorescence histomorphometry analyses that an increased rate of bone infiltration occurred from 0 to 2 weeks (p < 0.05) of implantation for the HA-high group (2.9 ± 0.5 mm) as compared with HA-empty (1.8 ± 0.8 mm) and HA-low (1.3 ± 0.2 mm) groups. No significant differences in bone formation within the scaffold or callus formation was observed between all groups after 4 weeks, with a significant increase in bone regenerated for all groups from 4 to 8 weeks (28.4% across groups). Although there was no difference in bone formation within scaffolds, callus formation was significantly higher in HA-empty scaffolds (100.9 ± 14.1 mm(3) ) when compared with HA-low (57.8 ± 7.3 mm(3) ; p ≤ 0.003) and HA-high (69.2 ± 10.4 mm(3) ; p ≤ 0.02) after 8 weeks. These data highlight the need for a better understanding of the parameters critical to the success of cell-seeded HA scaffolds for bone regeneration.

  16. Phase stability and biological property evaluation of plasma sprayed hydroxyapatite coatings for orthopedic and dental applications.

    PubMed

    Vahabzadeh, Sahar; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2015-04-01

    In this work we have investigated the effects of strontium (Sr) dopant on in vitro protein release kinetics and in vivo osteogenic properties of plasma sprayed hydroxyapatite (HA) coatings, along with their dissolution behavior. Plasma sprayed HA coatings are widely used in load-bearing implants. Apart from osseointegration, the new generation of HA coating is expected to deliver biomolecules and/or drugs that can induce osteoinduction. This paper reports the preparation of crystalline and amorphous HA coatings on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray, and their stability at different solution pH. Coatings prepared at 110 mm working distance from the nozzle showed an average Ca ion release of 18 and 90 ppm in neutral and acidic environments, respectively. Decreasing the working distance to 90 mm resulted in the formation of a coating with less crystalline HA and phases with higher solubility products, and consequently higher dissolution over 32 days. A 92% release of a model protein bovine serum albumin (BSA) in phosphate buffer with pH of 7.4 was measured for Sr-doped HA (Sr-HA) coating, while only a 72% release could be measured for pure HA coating. Distortion of BSA during adsorption on coatings revealed a strong interaction between the protein and the coating, with an increase in α-helix content. Osteoid formation was found on Sr-HA implants as early as 7 weeks post implantation compared to HA coated and uncoated Ti implants. After 12 weeks post implantation, osteoid new bone was formed on HA implants; whereas, bone mineralization started on Sr-HA samples. While no osteoid was formed on bare Ti surfaces, bone was completely mineralized on HA and Sr-HA coatings after 16 weeks post implantation. Our results show that both phase stability and chemistry can have a significant influence toward in vitro and in vivo response of HA coatings on Ti implants.

  17. Mechanical properties and in vivo study of modified-hydroxyapatite/polyetheretherketone biocomposites.

    PubMed

    Ma, Rui; Li, Qiankuan; Wang, Lin; Zhang, Xianghua; Fang, Lin; Luo, Zhongkuan; Xue, Bai; Ma, Lei

    2017-04-01

    Polyether ether ketone (PEEK) has received much attention for its excellent mechanical properties and biocompatibility. Here, the silane coupling agent KH560 [γ-(2,3-epoxypropoxy)propyltrimethoxysilane] is used for graft modification of bioactive HA (hydroxyapatite) particles and for preparing HA/PEEK composites via a hot-press molding method. The prepared HA/PEEK composites were tested for their mechanical properties with SEM (scanning electron microscopy), infrared spectroscopy, and thermo-analysis. The results show that silane coupling KH-560 modifies HA successfully and that the tensile strengths of HA/PEEK and m-HA/PEEK composites indicate an increasing and then a decreasing tendency with increasing HA contents. The non-modified HA/PEEK composites display the same trend as the modified specimens with lower tensile strength and consist of sharp points. When the HA content is 5wt.%, the tensile strength of m-HA/PEEK composite reaches its maximum, which is 23% higher than that of pure PEEK specimens. The in vivo experiments of m-HA/PEEK used a biomechanical push-out test, SEM, optical microscopy, and an Image-Pro Express C image analysis system. The growth of the bone tissues around the m-HA/PEEK composites with an HA content of 5wt.% is better than that of specimens with different HA contents. This finding shows the nano-scale effect of the bioactive filler HA in PEEK substrates, which obviously contributes to the growth of the surrounding bone issues in vivo. This study could provide theoretical support for the further promotion and application of high-performance engineering plastics such as PEEK in biomedical fields.

  18. Cancellous bone healing around strontium-doped hydroxyapatite in osteoporotic rats previously treated with zoledronic acid.

    PubMed

    Li, Yunfeng; Shui, Xueping; Zhang, Li; Hu, Jing

    2016-04-01

    Bisphosphonates (BPs) are potent anti-osteoporotic agents. Strontium-doped hydroxyapatite (HA) (SrHA) has been reported to increase bone density and improve trabecular microarchitecture in osteoporotic animals. But information about the effect of SrHA on the surrounding bone tissue in osteoporotic animals previously on BPs treatment is limited. We hypothesize that SrHA will induce increased bone density in the vicinity of the material when compared to HA, even in osteoporotic animals previously treated with BPs. HA and 10%SrHA (HA with 10 mol % calcium substituted by strontium) implants were prepared and characterized by scanning electronic microscopy (SEM), X-ray photoemission spectroscopy (XPS), and X-ray diffraction (XRD). Osteoporotic animal model was established by bilateral ovariectomy. Twelve weeks later, all OVX rats accepted subcutaneous injection of zoledronic acid (ZOL) at the dose of 1.5 μg/kg weekly for another twelve weeks. Subsequently, rod-shaped HA and SrHA implants were inserted in the distal femur of the OVX animals previously treated with ZOL. Eight weeks after implantation, specimens were harvested for histological and micro-computed tomography (micro-CT) analysis. Compared to HA, 10%SrHA raised the percent bone volume by 32.7%, the mean trabecular thickness by 36.5%, the mean trabecular number by 34.3%, the mean connectivity density by 38.4%, while the mean trabecular separation showed no significant difference. 10%SrHA also increased the bone area density by 36.3% in histological analysis. Results from this study indicated that 10%SrHA increased bone density and improved trabecular microarchitecture around implants in osteoporotic animals previously treated with ZOL when compared to HA.

  19. Electron microscopy of biomaterials based on hydroxyapatite

    SciTech Connect

    Suvorova, E. I. Klechkovskaya, V. V.; Komarov, V. F.; Severin, A. V.; Melikhov, I. V.; Buffat, P. A.

    2006-10-15

    Three types of biomaterials based on hydroxyapatite are synthesized and investigated. Hydroxyapatite nanocrystals or microcrystals precipitated from low-temperature aqueous solutions serve as the initial material used for preparing spherical porous granules approximately 300-500 {mu}m in diameter. Sintering of hydroxyapatite crystals at a temperature of 870 deg. C for 2 h or at 1000 deg. C (for 3 h) + 1200 deg. C (for 2 h) brings about the formation of solid ceramics with different internal structures. According to the electron microscopic data, the ceramic material prepared at 870 deg. C is formed by agglomerated hydroxyapatite nanocrystals, whereas the ceramics sintered at 1200 deg. C (with a bending strength of the order of 100 MPa) are composed of crystal blocks as large as 2 {mu}m. It is established that all the biomaterials have a single-phase composition and consist of the hydroxyapatite with a structure retained up to a temperature of 1200 deg. C.

  20. Intersectant Microstructure of Hydroxyapatite Sheets of Shankbone

    NASA Astrophysics Data System (ADS)

    Chen, B.; Luo, J.; Wang, J. G.; Yuan, Q.; Fan, J. H.

    Bone possesses excellent mechanical properties, which are closely related to its favorable microstructures optimized by nature through millions of years. In this work, a scanning electron microscope (SEM) was used to observe the microstructures of a shankbone. It showed that the bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. The hydroxyapatite layers are further composed of long and thin hydroxyapatite sheets. The hydroxyapatite sheets in different hydroxyapatite layers distribute along different orientations, which composes a kind of intersectant microstructure. The maximum pullout force of the intersectant microstructure was investigated and compared with that of 0° microstructure with their representative models. The result indicated that the maximum pullout force of the intersectant microstructure is markedly larger than that of the 0° microstructure, which was experimentally verified.

  1. Improve the Strength of PLA/HA Composite Through the Use of Surface Initiated Polymerization and Phosphonic Acid Coupling Agent

    PubMed Central

    Wang, Tongxin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Ting, Andy Hai; Dong, Quanxiao; Yang, Mingshu; Mitchell, James W.

    2011-01-01

    Bioresorbable composite made from degradable polymers, e.g., polylactide (PLA), and bioactive calcium phosphates, e.g., hydroxyapatite (HA), are clinically desirable for bone fixation, repair and tissue engineering because they do not need to be removed by surgery after the bone heals. However, preparation of PLA/HA composite from non-modified HA usually results in mechanical strength reductions due to a weak interface between PLA and HA. In this study, a calcium-phosphate/phosphonate hybrid shell was developed to introduce a greater amount of reactive hydroxyl groups onto the HA particles. Then, PLA was successfully grafted on HA by surface-initiated polymerization through the non-ionic surface hydroxyl groups. Thermogravimetric analysis indiated that the amount of grafted PLA on HA can be up to 7 %, which is about 50 % greater than that from the literature. PLA grafted HA shows significantly different pH dependent ζ-potential and particle size profiles from those of uncoated HA. By combining the phosphonic acid coupling agent and surface initiated polymerization, PLA could directly link to HA through covalent bond so that the interfacial interaction in the PLA/HA composite can be significantly improved. The diametral tensile strength of PLA/HA composite prepared from PLA-grafted HA was found to be over twice that of the composite prepared from the non-modified HA. Moreover, the tensile strength of the improved composite was 23 % higher than that of PLA alone. By varying additional variables, this approach has the potential to produce bioresorbable composites with improved mechanical properties that are in the range of natural bones, and can have wide applications for bone fixation and repair in load-bearing areas. PMID:22399838

  2. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    SciTech Connect

    Feng, Pei; Wei, Pingpin; Li, Pengjian; Gao, Chengde; Shuai, Cijun; Peng, Shuping

    2014-11-15

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

  3. Fracture modes under uniaxial compression in hydroxyapatite scaffolds fabricated by robocasting.

    PubMed

    Miranda, Pedro; Pajares, Antonia; Saiz, Eduardo; Tomsia, Antoni P; Guiberteau, Fernando

    2007-12-01

    The fracture modes of hydroxyapatite (HA) scaffolds fabricated by direct-write assembly (robocasting) are analyzed in this work. Concentrated HA inks with suitable viscoelastic properties were developed to enable the fabrication of prototype structures consisting of a 3-D square mesh of interpenetrating rods. The fracture behavior of these model scaffolds under compressive stresses is determined from in situ uniaxial tests performed in two different directions: perpendicular to the rods and along one of the rod directions. The results are analyzed in terms of the stress field calculated by finite element modeling (FEM). This analysis provides valuable insight into the mechanical behavior of scaffolds for bone tissue engineering applications fabricated by robocasting.

  4. Processing and mechanical characteristics of magnesium-hydroxyapatite metal matrix biocomposites.

    PubMed

    Del Campo, R; Savoini, B; Muñoz, A; Monge, M A; Pareja, R

    2017-05-01

    Magnesium/hydroxyapatite composites were produced by conventional extrusion and their mechanical behavior studied under uniaxial compression at room temperature. The results evidence the capability of the HA for strengthening the Mg material, lowering its microstructural anisotropy and inhibiting deformation twinning. They also reveal that the ECAP processing is effective for improving the grain structure and reducing the crystallographic texture of these composites, giving rise to a significant enhancement of their yield strength and microhardness although the ultimate compressive stress worsens. The analysis of the strain hardening rate of the flow curves demonstrates that the HA addition and the ECAP processing are also effective in inhibiting non-basal dislocation slip.

  5. Biodegradable HA-PLA 3-D porous scaffolds: effect of nano-sized filler content on scaffold properties.

    PubMed

    Kothapalli, Chandrasekhar R; Shaw, Montgomery T; Wei, Mei

    2005-11-01

    Scaffolds comprising poly(lactic acid) and nano-hydroxyapatite (HA) were prepared using the solvent-casting/salt-leaching technique. NaCl was used as the leaching agent. Nano-sized HA was synthesized by a hydrothermal method at 170 degrees C and autogenous pressure. High-resolution TEM imaging revealed that the HA particles were ellipsoidal-shaped with needle-like morphologies. The particles had an average size of approximately 25 nm in width and 150 nm in length with aspect ratios ranging from 6 to 8. As the HA content increased in the scaffold from 0 to 50 wt%, the compression modulus of the scaffolds increased from 4.72+/-1.2 to 9.87+/-1.8 MPa, while the yield strength from 0.29+/-0.03 to 0.44+/-0.01 MPa. Such polymeric scaffolds should be suitable materials for non-load sharing tissue-engineering applications.

  6. High-strength nanograined and translucent hydroxyapatite monoliths via continuous hydrothermal synthesis and optimized spark plasma sintering.

    PubMed

    Chaudhry, Aqif A; Yan, Haixue; Gong, Kenan; Inam, Fawad; Viola, Giuseppe; Reece, Mike J; Goodall, Josephine B M; ur Rehman, Ihtesham; McNeil-Watson, Fraser K; Corbett, Jason C W; Knowles, Jonathan C; Darr, Jawwad A

    2011-02-01

    The synthesis of high-strength, completely dense nanograined hydroxyapatite (bioceramic) monoliths is a challenge as high temperatures or long sintering times are often required. In this study, nanorods of hydroxyapatite (HA) and calcium-deficient HA (made using a novel continuous hydrothermal flow synthesis method) were consolidated using spark plasma sintering (SPS) up to full theoretical density in ∼5 min at temperatures up to 1000°C. After significant optimization of the SPS heating and loading cycles, fully dense HA discs were obtained which were translucent, suggesting very high densities. Significantly high three-point flexural strength values for such materials (up to 158 MPa) were measured. Freeze-fracturing of disks followed by scanning electron microscopy investigation revealed selected samples possessed sub-200 nm sized grains and no visible pores, suggesting they were fully dense.

  7. Evaluation of a setting reaction pathway in the novel composite TiHA-CSD bone cement by FT-Raman and FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Paluszkiewicz, Czesława; Czechowska, Joanna; Ślósarczyk, Anna; Paszkiewicz, Zofia

    2013-02-01

    The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800 °C, sintered at 1250 °C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

  8. Magnetoresponsive Photonic Microspheres with Structural Color Gradient.

    PubMed

    Lee, Seung Yeol; Choi, Jongkook; Jeong, Jong-Ryul; Shin, Jung H; Kim, Shin-Hyun

    2017-02-06

    Photonic Janus particles are created by alternately sputtering silica and titania on microspheres in order to obtain a structural color gradient. In addition, the microspheres are rendered magnetoresponsive. The Janus microspheres with optical and magnetic anisotropy enable on-demand control over orientation and structural color through manipulation of an external magnetic field, thereby being useful as active color pigments for reflection-mode displays.

  9. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  10. Microsphere coated substrate containing reactive aldehyde groups

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1984-01-01

    A synthetic organic resin is coated with a continuous layer of contiguous, tangential, individual microspheres having a uniform diameter preferably between 100 Angstroms and 2000 Angstroms. The microspheres are an addition polymerized polymer of an unsaturated aldehyde containing 4 to 20 carbon atoms and are covalently bonded to the substrate by means of high energy radiation grafting. The microspheres contain reactive aldehyde groups and can form conjugates with proteins such as enzymes or other aldehyde reactive materials.

  11. Glass microspheres for medical applications

    NASA Astrophysics Data System (ADS)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass

  12. Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

    PubMed

    Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

    2014-01-01

    Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments.

  13. Rheological, microstructural, and in vitro characterization of hybrid chitosan-polylactic acid/hydroxyapatite composites.

    PubMed

    Araújo, A B A; Lemos, A F; Ferreira, J M F

    2009-03-15

    In this work, hybrid chitosan/hydroxyapatite composites material were developed and characterized. The polymer matrix was first dissolved in polylactic acid, and then hydroxyapatite (HA) was added as filler material. The effects of the added amounts of a crosslinking agent (genipin) and of the concentrations of lactic acid, and of the presence of HA powder on the evolution of rheological properties were evaluated. A significant decrease of gelation time with increasing amounts of crosslinking agent was observed, the effect being even more pronounced in the presence of HA. The chitosan matrix and the composites with a chitosan/HA weight ratio of 2/5 were characterized using microstructural analysis and in vitro tests. The formation of large pore sizes in the chitosan-based scaffolds was favored by low concentrations of lactic acid and genipin. The in vitro tests in synthetic body fluid revealed an extensive formation of an apatitic layer onto the surface of the chitosan/HA composite scaffolds crosslinked with genipin.

  14. Local bisphosphonate release versus hydroxyapatite coating for stainless steel screw fixation in rat tibiae.

    PubMed

    Agholme, F; Andersson, T; Tengvall, P; Aspenberg, P

    2012-03-01

    Implant fixation in bone can be improved by a coating that delivers bisphosphonates locally, or by a hydroxyapatite (HA) coating. In this study, we compared these different types of coatings. For mechanical testing, 30 rats were assigned into three groups, and similar screws were implanted bilaterally in the proximal tibiae. The rats received screws that were either uncoated, coated with nano-crystalline hydroxyapatite or coated with a bisphosphonate releasing protein matrix. After 4 weeks, one screw was subjected to pull-out testing, and the contra-lateral one to torsion testing. For morphology, 30 rats were assigned to similar treatment groups, but received only one screw each. Bisphosphonates enhanced the pull-out force by 41% (P = 0.02) compared to controls, HA increased the pull-out force although not significantly. Conversely, HA increased the maximal torque by 64% (P = 0.02). Morphometry showed higher bone volume around bisphosphonate screws in comparison to HA-coated screws (P < 0.001) and controls (P < 0.001). The results suggest that bisphosphonates improve fixation by increasing the amount of surrounding bone, whereas HA mainly improves bone to implant attachment.

  15. Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials.

    PubMed

    Mohamed, Khaled R; Beherei, Hanan H; El Bassyouni, Gehan T; El Mahallawy, Nahed

    2013-10-01

    In the current study, the semiconducting metal oxides such as nano-ZnO and SiO2 powders were prepared via sol-gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO2 were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO2 or SiO2/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites.

  16. Enhanced colloidal stability of hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Borum, La Rhonda Terese

    Hydroxyapatite, Ca10(PO4)6(OH) 2 is the most thermodynamically stable calcium phosphate in physiological environments. Hence, it is the main inorganic mineral found in bone and teeth. Its colloidal stability, however, is poor because hydroxyapatite (HAp) particles exhibit sediment formation upon standing at short time periods, where agglomerates form and lead to non-homogeneous suspensions. Surface modification is a promising method to tailor the colloidal stability of hydroxyapatite for biomaterial applications. Three techniques to modify the HAp surface and enhance the colloidal stability of HAp were investigated. Modified particles were characterized by methods sensitive to surface chemistry changes, such as sedimentation studies, diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), Brunauer-Emmett-Teller (BET) surface area, and electrophoresis. Sedimentation studies demonstrated how effective each technique was in improving the colloidal stability of hydroxyapatite particles. Electrophoresis provided information on electrostatic interactions within each system. The first technique entailed an esterification reaction of the HAp surface with dodecyl alcohol at elevated temperatures. DRIFT results showed that dodecyl groups from the alcohol replaced acidic hydroxyl and phosphate sites on the HAp surface, giving rise to enhanced colloidal stability through steric interactions in ethanol suspensions. TGA curves gave insight to the degree of esterification for the esterified particles. Higher reaction temperatures give rise to a higher degree of esterification resulting in better colloidal stability. The second technique applied a silica coating on the HAp surface by the hydrolysis of tetraethyl orthosilicate in ethanol. Silica was coated onto the HAp surface at 5--75 wt% loading amounts. A combination of acid dissolution and x-ray diffraction (XRD), along with BET showed that the silica coating is complete at 50 wt% silica loading. The silica coating

  17. Adsorption of chlorhexidine on synthetic hydroxyapatite and in vitro biological activity.

    PubMed

    de Souza, Carlos A Soriano; Colombo, Ana Paula V; Souto, Renata M; Silva-Boghossian, Carina M; Granjeiro, Jose M; Alves, Gutemberg G; Rossi, Alexandre M; Rocha-Leão, Maria Helena M

    2011-10-15

    The kinetic of chlorhexidine digluconate (CHXDG) uptake from aqueous solution by hydroxyapatite (HA) was investigated by ultraviolet (UV) analysis performed in HA powder (UV-solid) after the CHX adsorption. Adsorption isotherm of chlorhexidine (CHX) uptake was modeled by a combination of Languimir and Langmuir-Freundlich mechanisms. Strong molecule-molecule interactions and positive cooperativity predominated in the surface when CHX concentration was above 8.6 μg(CHX)/mg(HA). UV-solid spectra (shape, intensity and band position) of CHX bound to HA revealed that long-range molecular structures, such as aggregates or micelles, started to be formed at low CHX concentrations (1.52 μg(CHX)/mg(HA)) and predominated at high concentrations. Grazing-incidence X-ray diffraction (GIXRD) analysis from synchrotron radiation discarded the formation of crystalline structures on HA surface or precipitation of CHX crystalline salts, as suggested in previous works. The effect of the HA/CHX association on HA in vitro bioactivity, cytotoxicity and CHX antimicrobial activity was evaluated. It was shown that CHX did not inhibit the precipitation of a poorly crystalline apatite at HA/CHX surface after soaking in simulating body fluid (SBF). Cell viability studies after exposure to extracts of HA and HA/CHX showed that both biomaterials did not present significant in vitro toxicity. Moreover, HA/CHX inhibited Enterococcus faecalis growth for up to 6 days, revealing that binding to HA did not affect antimicrobial activity of CHX and reduced bacterial adhesion. These results suggested that HA/CHX association could result in a potential adjuvant antimicrobial system for clinical use.

  18. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    PubMed Central

    Ma, Ming-Guo

    2012-01-01

    Hierarchically nanosized hydroxyapatite (HA) with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours. Objective The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA) with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks. Methods A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did not decrease with the increasing concentration of hierarchically nanostructured HA added. Conclusion A novel, simple and reliable hydrothermal route had been developed for the synthesis of

  19. Electrophoretic deposition of double-layer HA/Al composite coating on NiTi.

    PubMed

    Karimi, Esmaeil; Khalil-Allafi, Jafar; Khalili, Vida

    2016-01-01

    In order to improve the bioactivity of NiTi alloys, which are being known as the suitable materials for biomedical applications, numerous NiTi disks were electrophoretically coated by hetero-coagulated hydroxyapatite/aluminum composite coatings in three main voltages from suspensions with different Al concentrations. In this paper, the amount of Ni ions release and bioactivity of prepared samples as well as bonding strength of the coating to substrate were investigated. The surface characterization of the coating by XRD, EDX, SEM, and FTIR showed that HA particles bonded by Al particles. It caused the formation of a free crack coating on NiTi disks. Moreover, the bonding strength of HA/Al coatings to NiTi substrate were improved by two times as compared to that of the pure HA coatings. Immersing of coated samples in SBF for 1 week showed that apatite formation ability was improved on HA/Al composite coating and Ni ions release from the surface of composite coating decreased. These results induce the appropriate bioactivity and biocompatibility of the deposited HA/Al composite coatings on NiTi disks.

  20. Effect of blending HA-g-PLLA on xanthohumol-loaded PLGA fiber membrane.

    PubMed

    Qiao, Tiankui; Jiang, Suchen; Song, Ping; Song, Xiaofeng; Liu, Qimin; Wang, Lijuan; Chen, Xuesi

    2016-10-01

    Electropsun poly (lactide-co-glycolide) (PLGA) fiber membrane loaded xanthohumol (XN) has been developed using a co-solvent system of chloroform and dimethylformamide. To enhance its biological functionality as bone tissue engineering scaffolds, 5wt% hydroxyapatite grafted poly (l-lactic acid) (HA-g-PLLA) is blended into the spinning solution. The purpose of the present work is to disclose the effect of blending HA-g-PLLA on the corresponding properties of the medicated fiber membrane including morphology, thermodynamics, wettability, drug release, mechanics as well as cytotoxicity. XN and HA-g-PLLA can be well blended with PLGA to make fibers. Blending HA-g-PLLA not only turns amorphous XN/PLGA fiber membrane into crystal structure, but also changes the membranous wettability. Various medicated membranes exhibit the sustained release profiles. Drug release rate of the ternary membrane with HA-g-PLLA is slower compared to the binary XN/PLGA, and for the ternary membrane, the drug release accelerates with increasing XN content. A model is proposed to account for the drug release process. Tensile testing shows that at 10% of XN, the comprehensive mechanics of the ternary is preferable to the binary. At the same time, these fiber membranes are no cytotoxicity.

  1. Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings.

    PubMed

    Zhao, J; Lu, X; Duan, K; Guo, L Y; Zhou, S B; Weng, J

    2009-11-01

    Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity (approximately 85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly(D,L-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields.

  2. Hydroxyapatite and fluor-hydroxyapatite layered film on titanium processed by a sol-gel route for hard-tissue implants.

    PubMed

    Kim, Hae-Won; Knowles, Jonathan C; Salih, Vehid; Kim, Hyoun-Ee

    2004-10-15

    A double-layered coating, consisting of a hydroxyapatite (HA) outer film and a fluor-hydroxyapatite (FHA) inner film, was produced on a Ti substrate by a sol-gel route to improve the biocompatibility and functionality of the system. Dissolution behavior of and in vitro cellular responses to the layered film were investigated. Calcium nitrate and triethyl phosphite were used for calcium and phosphate precursors, respectively, and ammonium fluoride was added as a fluorine-ion source for FHA. The FHA layer was deposited on Ti by spin coating and subsequent heat treatment at 550 degrees C for 30 min in air, and then the HA layer was laid down over the FHA-coated Ti under the same conditions. After heat treatment, characteristic apatite structures and phases were developed on both FHA and HA films. The cross-section view of the HA/FHA film clearly showed a double-layered structure on Ti with each layer approximately 0.6-0.8-microm thickness. The coating layer was highly uniform and dense, and adhered to Ti substrate strongly with an adhesion strength of about 40 MPa. The in vitro solubility of the HA/FHA layered film in a physiological solution was between that of HA and FHA pure film, and the dissolution profile was quite biphasic, that is, an initial rapid period and a slowdown with increasing time, reflecting the gradient solubility of the fast HA outer structure/slow FHA inner structure. The human osteoblast-like HOS TE85 cells cultured on the HA/FHA layered film attached, spread, and grew favorably. The proliferation rate of the cells on the layered film was significantly higher (considered at p < 0.05 for n = 6) than that on Ti substrate and was similar to that on pure HA film. The alkaline phosphatase (ALP) activity and osteocalcin (OC) produced by the cells on the layered film were significantly higher (considered at p < 0.05 for n = 6) than those on Ti substrate. Moreover, the ALP and OC levels of cells on the layered film showed the trends of HA outer

  3. Strength and fatigue properties of three-step sintered dense nanocrystal hydroxyapatite bioceramics

    NASA Astrophysics Data System (ADS)

    Guo, Wen-Guang; Qiu, Zhi-Ye; Cui, Han; Wang, Chang-Ming; Zhang, Xiao-Jun; Lee, In-Seop; Dong, Yu-Qi; Cui, Fu-Zhai

    2013-06-01

    Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA ceramics limited their applications, because previous sintering methods produced HA ceramics with crystal sizes greater than nanometer range. In this study, nano-sized HA powder was employed to fabricate dense nanocrystal HA ceramic by high pressure molding, and followed by a three-step sintering process. The phase composition, microstructure, crystal dimension and crystal shape of the sintered ceramic were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties of the HA ceramic were tested, and cytocompatibility was evaluated. The phase of the sintered ceramic was pure HA, and the crystal size was about 200 nm. The compressive strength and elastic modulus of the HA ceramic were comparable to human cortical bone, especially the good fatigue strength overcame brittleness of traditional sintered HA ceramics. Cell attachment experiment also demonstrated that the ceramics had a good cytocompatibility.

  4. The physical and chemical properties of the polyvinylalcohol/polyvinylpyrrolidone/hydroxyapatite composite hydrogel.

    PubMed

    Ma, Yahui; Bai, Tongchun; Wang, Fei

    2016-02-01

    A hydrogel of polyvinylalcohol (PVA)/polyvinylpyrrolidone (PVP)/hydroxyapatite (HA) was prepared by a repeated freezing and thawing technique. The effect of HA on the hydrogel was evaluated by comparing the physical and chemical properties of PVA/PVP/HA and PVA/PVP hydrogels. By using theoretical models, the information about the swelling kinetics and the dehydration kinetics have been obtained. From the analysis of structure, mechanical properties, and molecular interaction, the application of PVA/PVP/HA hydrogel as a biomaterial has been evaluated. Relative to PVA/PVP, the PVA/PVP/HA hydrogel is of denser network structure, lower water content, larger storage modulus, and higher dehydration activation energy. These results reveal that, as HA fills in the hydrogel, the molecular interaction is enhanced, the free space of network is compressed, and the diffusion activation energy of water is increased. In spite of its water content being decreased, it is still in the range of meeting the requirement of bio-application. When the hydrogel is subjected to external forces, the matrix will transfer the load to the HA powder, thus enhance the strength of the hydrogel. For application in bio-materials, HA will still have osteoinductivity because its crystalline structure is not interrupted in PVA/PVP/HA hydrogel environment.

  5. Mechanical properties and crystallization behavior of hydroxyapatite/poly(butylenes succinate) composites.

    PubMed

    Guo, Wenmin; Zhang, Yihe; Zhang, Wei

    2013-09-01

    Biodegradable synthetic polymers have attracted much attention nowadays, and more and more researches have been done on biodegradable polymers due to their excellent mechanical properties, biocompatibility, and biodegradability. In this work, hydroxyapatite (HA) particles were melt-mixing with poly (butylenes succinate) (PBS) to prepare the material, which could be used in the biomedical industry. To develop high-performance PBS for cryogenic engineering applications, it is necessary to investigate the cryogenic mechanical properties and crystallization behavior of HA/PBS composites. Cryogenic mechanical behaviors of the composites were studied in terms of tensile and impact strength at the glass transition temperature (-30°C) and compared to their corresponding behaviors at room temperature. With the increase of HA content, the crystallization of HA/PBS composites decreased and crystallization onset temperature shifted to a lower temperature. The diameter of spherulites increased at first and decreased with a further HA content. At the same time, the crystallization rate became slow when the HA content was no more than 15wt% and increased when HA content reached 20wt%. In all, the results we obtained demonstrate that HA/PBS composites reveal a better tensile strength at -30°C in contrast to the strength at room temperature. HA particles with different amount affect the crystallization of PBS in different ways.

  6. Densification Process of OH Controlled Hydroxyapatite Ceramics by Spark Plasma Sintering

    SciTech Connect

    Kawagoe, D.; Koga, Y.; Ishida, E. H.; Ioku, K.

    2006-05-15

    Calcium hydroxyapatite, Ca10(PO4)6(OH)2:HA, is the inorganic principle component of natural bones and teeth. It has been already suggested that the amount of OH ion in the crystal structure of HA is closely related to the biocompatibility. The amount of OH ion in current HA, however, has not been controlled. In order to prepare more functional HA ceramics, the amount of OH ion must be controlled. In this study, HA ceramics with different OH amount were prepared from fine HA crystals by spark plasma sintering (SPS). In order to reveal the ideal sintering conditions for preparation of transparent ceramics, densification process on SPS was investigated. The samples were pressed uniaxialy under 60 MPa, and then they were heated by SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min with the heating rate of 25 deg. C{center_dot}min-1. The quantity of OH ion in HA ceramics sintered by SPS was decreased with increasing temperature of sintering. Transparent HA ceramics were prepared by SPS at 900 deg. C and 1000 deg. C. In analysis of the densification behavior during sintering of HA by SPS, dominant sintering mechanism was plastic flow of densification. Transparent ceramics should be the most suitable materials to investigate the interface between human cells and ceramics.

  7. Engineering nanocages with polyglutamate domains for coupling to hydroxyapatite biomaterials and allograft bone.

    PubMed

    Culpepper, Bonnie K; Morris, David S; Prevelige, Peter E; Bellis, Susan L

    2013-03-01

    Hydroxyapatite (HA) is the principal constituent of bone mineral, and synthetic HA is widely used as a biomaterial for bone repair. Previous work has shown that polyglutamate domains bind selectively to HA and that these domains can be utilized to couple bioactive peptides onto many different HA-containing materials. In the current study we have adapted this technology to engineer polyglutamate domains into cargo-loaded nanocage structures derived from the P22 bacteriophage. P22 nanocages have demonstrated significant potential as a drug delivery system due to their stability, large capacity for loading with a diversity of proteins and other types of cargo, and ability to resist degradation by proteases. Site-directed mutagenesis was used to modify the primary coding sequence of the P22 coat protein to incorporate glutamate-rich regions. Relative to wild-type P22, the polyglutamate-modified nanocages (E2-P22) exhibited increased binding to ceramic HA disks, particulate HA and allograft bone. Furthermore, E2-P22 binding was HA selective, as evidenced by negligible binding of the nanocages to non-HA materials including polystyrene, agarose, and polycaprolactone (PCL). Taken together these results establish a new mechanism for the directed coupling of nanocage drug delivery systems to a variety of HA-containing materials commonly used in diverse bone therapies.

  8. Sol-Gel-Derived Hydroxyapatite-Carbon Nanotube/Titania Coatings on Titanium Substrates

    PubMed Central

    Ji, Xiaoli; Lou, Weiwei; Wang, Qi; Ma, Jianfeng; Xu, Haihong; Bai, Qing; Liu, Chuantong; Liu, Jinsong

    2012-01-01

    In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO2) double layer coatings were successfully developed on titanium (Ti) substrates intended for biomedical applications. A TiO2 coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO2 coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO2 double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO2 coatings on Ti substrates might be a promising material for bone replacement. PMID:22606041

  9. Preparation and characterization of chitosan-natural nano hydroxyapatite-fucoidan nanocomposites for bone tissue engineering.

    PubMed

    Lowe, Baboucarr; Venkatesan, Jayachandran; Anil, Sukumaran; Shim, Min Suk; Kim, Se-Kwon

    2016-12-01

    Solid three dimensional (3D) composite scaffolds for bone tissue engineering were prepared using the freeze-drying method. The scaffolds were composed of chitosan, natural nano-hydroxyapatite (nHA) and fucoidan in the following combinations: chitosan, chitosan-fucoidan, chitosan-nHA, and chitosan-nHA-fucoidan. Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) were used to determine the physiochemical constituents and the morphology of the scaffolds. The addition of nHA into the chitosan-fucoidan composite scaffold reduced the water uptake and water retention. FT-IR analysis confirmed the presence of a phosphate group in the chitosan-nHA-fucoidan scaffold. This group is present because of the presence of nHA (isolated via alkaline hydrolysis from salmon fish bones). Microscopic results indicated that the dispersion of nHA and fucoidan in the chitosan matrix was uniform with a pore size of 10-400μm. The composite demonstrated a suitable micro architecture for cell growth and nutrient supplementation. This compatibility was further elucidated in vitro using periosteum-derived mesenchymal stem cells (PMSCs). The cells demonstrated high biocompatibility and excellent mineralization for the chitosan-nHA-fucoidan scaffold. We believe that a chitosan-nHA-fucoidan composite is a promising biomaterial for the scaffold that can be used for bone tissue regeneration.

  10. Preparation and Properties of Nano-Hydroxyapatite/Gelatin/Poly(vinyl alcohol) Composite Membrane.

    PubMed

    Liao, Haotian; Shi, Kun; Peng, Jinrong; Qu, Ying; Liao, Jinfeng; Qian, Zhiyong

    2015-06-01

    In this study, the bone-like composite membrane based on blends of gelatin (Gel), nano-hydroxyapatite (n-HA) and poly(vinyl alcohol) (PVA) was fabricated by solvent casting and evaporation methods. The effect of n-HA content and the ratio of Gel/PVA on the properties of the composite was investigated. The Gel/PVA and n-HA/Gel/PVA composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), water contact angle measurement and scanning electron microscopy (SEM). The mechanical properties of the composites were determined by tensile tests. The as prepared composite membranes exhibited hydrophobility, the water contact angle of composite membrane was 126.6 when its mass ratio of n-HA/Gel/PVA was 10/50/40. The tensile strength of composite membranes was greatly increased due to the introduction of n-HA, and the tensile strength was increased to 74.92 MPa when the mass ratio of n-HA/Gel/PVA was 10/50/40. SEM observation indicated that n-HA was dispersed in the membranes and a sea-island structure was formed in the n-HA/Gel/PVA composite membranes, resulting in a significant increase in tensile strength. The as-prepared n-HA/Gel/PVA composite membranes may be applied in the field of bone tissue engineering.

  11. In vitro differences of hydroxyapatite from different resources in simulated body fluid.

    PubMed

    Hashim, N; Sabudin, S; Ibrahim, S; Zin, N M; Bakar, S H A; Fazan, F

    2004-05-01

    Hydroxyapatite (HA; Ca10(PO4)6(OH)2), is one of the significant implant materials used in Orthopaedics and Dental applications. However, synthetically produced HA may not be stable under ionic environment, which it will unavoidably encounter during its applications. In this paper, the in vitro effects of three HA materials derived from different resources, i.e. commercial HA (HAC), synthesised HA from pure chemicals (HAS) and synthesised HA from kapur sireh; derived traditionally from natural limestone (HAK), were studied. The HA disc samples were prepared and immersed in simulated body fluid (SBF) for 31-day period. The evaluation conducted focuses on the changes of the pH and the Calcium ion (Ca-ion) and Phosphate ion (P-ion) concentrations in the SBF solution, as well as the XRD and SEM data representing the reactions on the HA materials. From the XRD, it was found that HAK has the smallest crystallite sizes, which in turn affect the pH of the SBF during immersion. The Ca and P-ion concentrations generally decrease over time at different rates for different HA. Upon 1-day immersion in SBF, apatite growth was observed onto all three surfaces, which became more pronounced after 3-day immersion. However, the appetites formed were observed to be different in shapes and sizes. The reasons for the difference in the apatite-crystals and their subsequent effects on cells are still being investigated.

  12. Sol-gel-derived hydroxyapatite-carbon nanotube/titania coatings on titanium substrates.

    PubMed

    Ji, Xiaoli; Lou, Weiwei; Wang, Qi; Ma, Jianfeng; Xu, Haihong; Bai, Qing; Liu, Chuantong; Liu, Jinsong

    2012-01-01

    In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO(2)) double layer coatings were successfully developed on titanium (Ti) substrates intended for biomedical applications. A TiO(2) coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO(2) coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO(2) double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO(2) coatings on Ti substrates might be a promising material for bone replacement.

  13. Hydroxyapatite bioactivated bacterial cellulose promotes osteoblast growth and the formation of bone nodules

    PubMed Central

    2012-01-01

    The goal of this study was to investigate the feasibility of bacterial cellulose (BC) scaffold to support osteoblast growth and bone formation. BC was produced by culturing Acetobacter xylinum supplemented with hydroxyapatite (HA) to form BC membranes (without HA) and BC/HA membranes. Membranes were subjected to X-ray photoelectron spectroscopy (XPS) analysis to determine surface element composition. The membranes were further used to evaluate osteoblast growth, alkaline phosphatase activity and bone nodule formation. BC was free of calcium and phosphate. However, XPS analysis revealed the presence of both calcium (10%) and phosphate (10%) at the surface of the BC/HA membrane. Osteoblast culture showed that BC alone was non-toxic and could sustain osteoblast adhesion. Furthermore, osteoblast adhesion and growth were significantly (p ≤0.05) increased on BC/HA membranes as compared to BC alone. Both BC and BC/HA membranes improved osteoconductivity, as confirmed by the level of alkaline phosphatase (ALP) activity that increased from 2.5 mM with BC alone to 5.3 mM with BC/HA. BC/HA membranes also showed greater nodule formation and mineralization than the BC membrane alone. This was confirmed by Alizarin red staining (ARS) and energy dispersive X-ray spectroscopy (EDX). This work demonstrates that both BC and BC/HA may be useful in bone tissue engineering. PMID:23174338

  14. Peptide decorated nano-hydroxyapatite with enhanced bioactivity and osteogenic differentiation via polydopamine coating.

    PubMed

    Sun, Yuhua; Deng, Yi; Ye, Ziyou; Liang, Shanshan; Tang, Zhihui; Wei, Shicheng

    2013-11-01

    To be better used as implant materials in bone graft substitutes, bioactivity and osteogenesis of nano-hydroxyapatite (nano-HA) need to be further enhanced. Inspired by adhesive proteins in mussels, here we developed a novel bone forming peptide decorated nano-HA material. In this study, nano-HA was coated by one-step pH-induced polymerization of dopamine, and then the peptide was grafted onto polydopamine (pDA) coated nano-HA (HA-pDA) through catechol chemistry. Our results demonstrated that the peptide-conjugated nano-HA crystals could induce the adhesion and proliferation of MG-63 cells. Moreover, the highly alkaline phosphatase activity of the functionalized nano-HA indicated that the grafted peptide could maintain its biological activity after immobilization onto the surface of HA-pDA, especially at the concentration of 100μg/mL. These modified nano-HA crystals with better bioactivity and osteogenic differentiation hold great potential to be applied as bioactive materials in bone repairing, bone regeneration and bio-implant coating applications.

  15. In Vitro Corrosion and Cytocompatibility Properties of Nano-Whisker Hydroxyapatite Coating on Magnesium Alloy for Bone Tissue Engineering Applications

    PubMed Central

    Yang, Huawei; Yan, Xueyu; Ling, Min; Xiong, Zuquan; Ou, Caiwen; Lu, Wei

    2015-01-01

    We report here the successful fabrication of nano-whisker hydroxyapatite (nHA) coatings on Mg alloy by using a simple one-step hydrothermal process in aqueous solution. The nHA coating shows uniform structure and high crystallinity. Results indicate that nHA coating is promising for improving the in vitro corrosion and cytocompatibility properties of Mg-based implants and devices for bone tissue engineering. In addition, the simple hydrothermal deposition method used in the current study is also applicable to substrates with complex shapes or surface geometries. PMID:25789500

  16. Osteoblast interactions with various hydroxyapatite based biomaterials consolidated using a spark plasma sintering technique.

    PubMed

    Xu, J L; Khor, K A; Lu, Y W; Chen, W N; Kumar, R

    2008-01-01

    This study investigated the osteoblast behaviors on various hydroxyapatite based biomaterials that were consolidated at 1100 degrees C for 3 min by a spark plasma sintering technique. The osteoblasts from human fetal osteoblast cell line were cultured in the medium on the various biomaterials surfaces (HA, RF21, 1SiHA, and 5SiHA) to assess the cell morphology and proliferation as well as cell differentiation (alkaline phosphatase activity). Moreover, the bone gamma-carboxyglutamic protein or osteocalcin in the medium were determined at different periods of culture. The present results indicated that the amount of osteocalcin in the medium decreased during the periods of culture. The highest osteocalcin production obtained from the biomaterial 5SiHA after cell culture for 2 days demonstrated that the presence of silica in the biomaterials enhanced the cell differentiation by the rapid release of silicate and calcium ions.

  17. Porous scaffolds of polycaprolactone reinforced with in situ generated hydroxyapatite for bone tissue engineering.

    PubMed

    Fabbri, Paola; Bondioli, Federica; Messori, Massimo; Bartoli, Cristina; Dinucci, Dinuccio; Chiellini, Federica

    2010-01-01

    Polycaprolactone/hydroxyapatite (PCL/HA) composites were prepared by in situ generation of HA in the polymer solution starting from the precursors calcium nitrate tetrahydrate and ammonium dihydrogen phosphate via sol-gel process. Highly interconnected porosity was achieved by means of the salt-leaching technique using a mixture of sodium chloride and sodium bicarbonate as porogens. Structure and morphology of the PCL/HA composites were investigated by scanning electron microscopy, and mechanical properties were determined by means of tensile and compression tests. The possibility to employ the developed composites as scaffolds for bone tissue regeneration was assessed by cytotoxicity test of the PCL/HA composites extracts and cell adhesion and proliferation in vitro studies.

  18. [Research development of hydroxyapatite-based composites used as hard tissue replacement].

    PubMed

    Ning, Congqin; Dai, Kerong

    2003-09-01

    Hydroxyapatite has been considered as the most promising materials for hard tissue replacements, due to its similar chemical composition and crystallographic structure to that of bone mineral. But the brittleness is one of the most serious obstacles for its wider applications as load-bearing implants. Therefore, various HA composites get much attention. In the present paper, HA composites were introduced according to the kind of reinforcement. Although bioactive ceramics, bioactive glass or glass-ceramic, bio-inactive ceramics, polymers and metals all have been used to fabricate HA composites, no one can well satisfy the requirements for hard tissue replacement. The vital problem of the existing HA composites is that the biological properties cannot match with the mechanical properties well.

  19. The influence of sintering temperature on the porosity and strength of porous hydroxyapatite ceramics.

    PubMed

    Rusnah, M; Andanastuti, M; Idris, B

    2004-05-01

    The present paper reports on the influence of sintering temperature on the porosity and strength of porous hydroxyapatite (HA). HA powder was first prepared by the sol-gel precipitation method using calcium hydroxide and ortho-phosporic acid. The fine HA powder, measuring <50 microm was then mixed into a slurry with the addition of binder agent, being a mixture of sago and PVA. A small amount of sodium dodecyl sulphate was also used as a foaming agent. Porous HA samples were then prepared via slip casting technique. The surface morphology of the sintered samples was observed under scanning electron microscopy at 20 kV and the compositions were determined via SEM-EDX. A universal testing machine was used to determine the compaction strength of the sintered samples.

  20. Preparation of graded zirconia hydroxyapatite composite bioceramic and its immunocompatibility in vitro.

    PubMed

    Quan, Renfu; Yang, Disheng; Miao, Xudong; Wu, Xiaochun; Wang, Hongbin; Li, Wei

    2007-09-01

    To obtain immunocompatibility, graded zirconia-hydroxyapatite (ZrO(2)-HA) composite bioceramic and simplex ZrO(2)-HA composite bioceramic are prepared. Peripheral blood mononuclear cells (PBMCs) harvested from healthy individuals are cultured with the two ceramic extracts to assess their effect on the transformation of lymphocytes, apoptotic ratio, CD69 expression, and expression of cytokine of TNFalpha and IL-6, with or without phytohemoagglutinin (PHA)-stimulated cells. Ceramic extracts did not activate the resting lymphocytes, whereas the response of the PHA-stimulated cells was significantly modified. The PBMCs activated by graded ZrO(2)-HA composite bioceramic is noticeably smaller than that by simplex ZrO(2)-HA composite bioceramic; these results, however can only be seen under the amplified effect of PHA-stimulation.

  1. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, Richard W.; Hrubesh, Lawrence W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  2. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  3. Strontium and zoledronate hydroxyapatites graded composite coatings for bone prostheses.

    PubMed

    Boanini, Elisa; Torricelli, Paola; Sima, Felix; Axente, Emanuel; Fini, Milena; Mihailescu, Ion N; Bigi, Adriana

    2015-06-15

    Both strontium and zoledronate (ZOL) are known to be useful for the treatment of bone diseases associated to the loss of bone substance. In this work, we applied an innovative technique, Combinatorial Matrix-Assisted Pulsed Laser Evaporation (C-MAPLE), to deposit gradient thin films with variable compositions of Sr-substituted hydroxyapatite (SrHA) and ZOL modified hydroxyapatite (ZOLHA) on Titanium substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. The coatings display good crystallinity and granular morphology, which do not vary with composition. Osteoblast-like MG63 cells and human osteoclasts were co-cultured on the thin films up to 21 days. The results show that Sr counteracts the negative effect of relatively high concentration of ZOL on osteoblast viability, whereas both Sr and ZOL enhance extracellular matrix deposition. In particular, ZOL promotes type I collagen production, whereas Sr increases the production of alkaline phosphatase. Moreover, ZOL exerts a greater effect than Sr on osteoprotegerin/RANKL ratio and, as a consequence, on the reduction of osteoclast proliferation and activity. The deposition method allows to modulate the composition of the thin films and hence the promotion of bone growth and the inhibition of bone resorption.

  4. Microspheres in Plasma Display Panels

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Filling small bubbles of molten glass with gases is just as difficult as it sounds, but the technical staff at NASA is not known to shy away from a difficult task. When Microsphere Systems, Inc. (MSI), of Ypsilanti, Michigan, and Imaging Systems Technology, Inc. (IST), of Toledo, Ohio, were trying to push the limits of plasma displays but were having difficulty with the designs, NASA s Glenn Garrett Morgan Commercialization Initiative (GMCI) assembled key personnel at Glenn Research Center and Ohio State University for a brainstorming session to come up with a solution for the companies. They needed a system that could produce hollow, glass micro-sized spheres (microspheres) that could be filled with a variety of gasses. But the extremely high temperature required to force the micro-sized glass bubbles to form at the tip of a metal nozzle resulted in severe discoloration of the microspheres. After countless experiments on various glass-metal combinations, they had turned to the GMCI for help. NASA experts in advanced metals, ceramics, and glass concluded that a new design approach was necessary. The team determined that what was needed was a phosphate glass composition that would remain transparent, and they went to work on a solution. Six weeks later, using the design tips from the NASA team, Tim Henderson, president of MSI, had designed a new system in which all surfaces in contact with the molten glass would be ceramic instead of metal. Meanwhile, IST was able to complete a Phase I Small Business Innovation Research (SBIR) grant supported by the National Science Foundation (NSF) and supply a potential customer with samples of the microspheres for evaluation as filler materials for high-performance insulations.

  5. Nonaggregating Microspheres Containing Aldehyde Groups

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan

    1989-01-01

    Cobalt gamma irradiation of hydrophilic monomers in presence of acrolein yields exceptionally-stable, nonaggregating microspheres. Mixtures of 2-hydroxyethyl methacrylate (HEMA) and acrolein form homogeneous solutions in distilled water containing 0.4 percent polyethylene oxide (PEO). After deaeration with nitrogen, mixtures irradiated at room temperature with gamma rays from cobalt source; total exposure time 4 hours, at rate of 0.2 milliroentgen per hour. Reaction product centrifuged three times for purification and kept in distilled water.

  6. Making Latex Microspheres in Space

    NASA Technical Reports Server (NTRS)

    Kornfeld, D. M.; Vanderhoff, J. W.; El-Aasser, M. S.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.

    1986-01-01

    Equipment yields larger, more uniform particles. Two NASA reports describe first commercial product to be manufactured in space. Product monodisperse latex, suspension of spherical particles of essentially same diameter. Carried aboard Space Shuttle on its orbital missions, monodisperse latex reactor (MLR) produces spheres of much larger size than possible on Earth. Mircospheres 30 micrometers in diameter produced, whereas 5 micrometers is limit for Earthbound reactors. Microspheres as large as 100 micrometers scheduled for production in MLR.

  7. Research on the preparation, biocompatibility and bioactivity of magnesium matrix hydroxyapatite composite material.

    PubMed

    Linsheng, Li; Guoxiang, Lin; Lihui, Li

    2016-08-12

    In this paper, magnesium matrix hydroxyapatite composite material was prepared by electrophoretic deposition method. The optimal process parameters of electrophoretic deposition were HA suspension concentration of 0.02 kg/L, aging time of 10 days and voltage of 60 V. Animal experiment and SBF immersion experiment were used to test the biocompatibility and bioactivity of this material respectively. The SD rats were divided into control group and implant group. The implant surrounding tissue was taken to do tissue biopsy, HE dyed and organizational analysis after a certain amount of time in the SD rat body. The biological composite material was soaked in SBF solution under homeothermic condition. After 40 days, the bioactivity of the biological composite material was evaluated by testing the growth ability of apatite on composite material. The experiment results showed that magnesium matrix hydroxyapatite biological composite material was successfully prepared by electrophoretic deposition method. Tissue hyperplasia, connective tissue and new blood vessels appeared in the implant surrounding soft tissue. No infiltration of inflammatory cells of lymphocytes and megakaryocytes around the implant was found. After soaked in SBF solution, a layer bone-like apatite was found on the surface of magnesium matrix hydroxyapatite biological composite material. The magnesium matrix hydroxyapatite biological composite material could promot calcium deposition and induce bone-like apatite formation with no cytotoxicity and good biocompatibility and bioactivity.

  8. Substituted Hydroxyapatites with Antibacterial Properties

    PubMed Central

    Kolmas, Joanna; Groszyk, Ewa; Kwiatkowska-Różycka, Dagmara

    2014-01-01

    Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions) and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency. PMID:24949423

  9. [Fracture of macroporous hydroxyapatite prosthesis].

    PubMed

    Adetchessi, A T; Pech-Gourg, G; Metellus, P; Fuentes, S

    2012-12-01

    Different prosthesis implants are offered to perform a cranioplasty after a decompressive craniectomy when autologous bone graft cannot be used. The authors report the case of a 25-year-old man who benefited a unilateral decompressive craniectomy after a severe head trauma. Seven months later, a cranioplasty using custom macroporous hydroxyapatite prosthesis was performed. The postoperative course was marked by a generalized seizure leading to a traumatic head injury. The CT-scan showed a comminutive fracture of the prosthesis and an extradural hematoma. The patient underwent a removal of the fractured prosthesis and an evacuation of the extradural clot. The postoperative course was uneventful with a Glasgow outcome scale score at 5. A second cranioplasty using a polyether ether ketone (PEEK) implant was performed. Among cranioplasty prosthesis solutions, hydroxyapatite implants seem to have similar property to the bone. However, its weak mechanic resistance is an actual problem in patients susceptible to present generalized seizures with consecutive head impact. Hence, in patients with decompressive craniectomy who are exposed to potential brain injury, we favor the use of more resistant implant as PEEK prosthesis.

  10. Metalated nucleotide chemisorption on hydroxyapatite.

    PubMed

    Benedetti, Michele; Antonucci, Daniela; De Castro, Federica; Girelli, Chiara R; Lelli, Marco; Roveri, Norberto; Fanizzi, Francesco P

    2015-12-01

    The experiments here reported evidence on the importance of the residual charge of a nucleotide derivative, for the adsorption on nHAP (hydroxyapatite nanocrystals), in water solution. We found that the simple presence of phosphates on the nucleotide derivative does not guarantee adsorption on nHAP. On the other hand, we demonstrated that a cationic or neutral charge on a nucleotide derivative produces a strongly reduced chemical adsorption (chemisorption) whereas, in the presence of a net negative charge, relevant adsorption on nHAP is observed. The number of phosphates can only modulate the adsorption efficiency of a molecule provided that this latter bears an overall negative charge. The neutral zwitterionic nucleotide Pt(II) complexes, bearing negatively charged phosphates, are unable to give stable chemisorption. Previous considerations are important to model the binding ability of phosphate bearing nucleotide derivatives or molecules on hydroxyapatite. The findings reported in the present paper could be relevant in bone tissue targeting or nHAP mediated drug delivery.

  11. Substituted hydroxyapatites with antibacterial properties.

    PubMed

    Kolmas, Joanna; Groszyk, Ewa; Kwiatkowska-Różycka, Dagmara

    2014-01-01

    Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions) and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency.

  12. Characterization of Nano-Hydroxyapatite Synthesized from Sea Shells Through Wet Chemical Method

    NASA Astrophysics Data System (ADS)

    Santhosh, S.; Prabu, S. Balasivanandha

    2012-10-01

    Nano-hydroxyapatite (HA) was synthesized by a wet chemical reaction using powdered sea shells (CaO) as starting material which was converted to calcium hydroxide (Ca(OH)2) and subsequently reacted with phosphoric acid (H3PO4). Initially raw sea shells (CaCO3) were thermally converted to amorphous calcium oxide by heat treatment. Two sets of experiments were done; in the first experiment, HA powder was dried in an electric furnace and in the second experiment, the reactants were irradiated in a domestic microwave oven followed by microwave drying. In each set of experiments, the concentrations of the reactants were decreased gradually. HA was synthesized by slow addition of phosphoric acid (H3PO4) in to calcium hydroxide (Ca(OH)2) maintaining the pH of the solution at 10 to avoid the formation of calcium deficient apatites. In both the experiments, Ca:P ratio of 1.67 was maintained for the reagents. The synthesized samples showed X-ray diffraction (XRD) patterns corresponding to hydroxyapatite. The wet chemical process with furnace drying resulted in HA particles of size 7-34 nm, whereas microwave irradiated process yielded HA particles of size 34-102 nm as evidenced from XRD analyses. The above experimental work done by wet chemical synthesis to produce HA powder from sea shells is a simple processing method at room temperature. Microwave irradiation leads to uniform crystallite sizes as evident from this study, at differing concentrations of the reactants and is a comparatively easy method to synthesize HA. The high resolution scanning electron microscopy (HRSEM)/transmission electron microscopic (TEM) analyses revealed the characteristic rod-shaped nanoparticles of HA for the present study.

  13. Osseointegration of a hydroxyapatite-coated multilayered mesh stem.

    PubMed

    Kusakabe, Hiroshi; Sakamaki, Toyonori; Nihei, Kotaro; Oyama, Yasuo; Yanagimoto, Shigeru; Ichimiya, Masaru; Kimura, Jun; Toyama, Yoshiaki

    2004-07-01

    A new type of porous coating for hip prostheses called "multilayered mesh" was tested under weight-bearing conditions. The surface of the stem is constructed of titanium mesh produced by etching. The hip stems of hydroxyapatite (HA)-coated multilayered mesh and conventional beads were implanted into canine right hips, and animals were killed 3, 6 and 10 weeks and 6 and 12 months after implantation. Shear strength between the implant and the bone was evaluated by the push-out test. Bone ingrowth was calculated from backscattered electron imaging-scanning electron microscopy (BEI-SEM) images of transverse sections. Toluidine blue stained sections and the BEI-SEM images were evaluated histologically. The break sites of the specimens after the push-out test were evaluated on BEI-SEM images of longitudinal sections. The mean push-out strength of the HA-coated multilayered mesh samples was greater than that of the beads-coated samples every time tested, and the HA-coated multilayered mesh implants had significantly stronger push-out strength at 3 and 6 weeks (p<0.05). The strength of the HA-coated multilayered mesh implants was even greater at 6 and 12 months, whereas the strength of the beads-coated samples decreased. The HA-coated multilayered mesh implants showed significantly higher percentages of bone ingrowth than the beads-coated implants every time tested, except at 6 months (p<0.05). At 6 and 12 months, the bone ingrowth data for the HA-coated multilayered mesh implants increased, whereas it decreased for the beads-coated implants. The new bone formation had reached the bottom of the porous area of the HA-coated multilayered mesh surface by 3 weeks, but not had reached the bottom of the conventional beads surface. At 6 and 12 months, the smaller pores of the bead surface stopped the thickening of trabecular bone, and at 12 months, the break sites were at the bone-implant interface of the bead surface, whereas they were on the bone side of the HA

  14. PLGA/nHA hybrid nanofiber scaffold as a nanocargo carrier of insulin for accelerating bone tissue regeneration

    PubMed Central

    2014-01-01

    The development of tissue engineering in the field of orthopedic surgery is booming. Two fields of research in particular have emerged: approaches for tailoring the surface properties of implantable materials with osteoinductive factors as well as evaluation of the response of osteogenic cells to these fabricated implanted materials (hybrid material). In the present study, we chemically grafted insulin onto the surface of hydroxyapatite nanorods (nHA). The insulin-grafted nHAs (nHA-I) were dispersed into poly(lactide-co-glycolide) (PLGA) polymer solution, which was electrospun to prepare PLGA/nHA-I composite nanofiber scaffolds. The morphology of the electrospun nanofiber scaffolds was assessed by field emission scanning electron microscopy (FESEM). After extensive characterization of the PLGA/nHA-I and PLGA/nHA composite nanofiber scaffolds by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM), the PLGA/nHA-I and PLGA/nHA (used as control) composite nanofiber scaffolds were subjected to cell studies. The results obtained from cell adhesion, alizarin red staining, and Von Kossa assay suggested that the PLGA/nHA-I composite nanofiber scaffold has enhanced osteoblastic cell growth, as more cells were proliferated and differentiated. The fact that insulin enhanced osteoblastic cell proliferation will open new possibilities for the development of artificial scaffolds for bone tissue regeneration. PMID:25024679

  15. PLGA/nHA hybrid nanofiber scaffold as a nanocargo carrier of insulin for accelerating bone tissue regeneration

    NASA Astrophysics Data System (ADS)

    Haider, Adnan; Gupta, Kailash Chandra; Kang, Inn-Kyu

    2014-06-01

    The development of tissue engineering in the field of orthopedic surgery is booming. Two fields of research in particular have emerged: approaches for tailoring the surface properties of implantable materials with osteoinductive factors as well as evaluation of the response of osteogenic cells to these fabricated implanted materials (hybrid material). In the present study, we chemically grafted insulin onto the surface of hydroxyapatite nanorods (nHA). The insulin-grafted nHAs (nHA-I) were dispersed into poly(lactide-co-glycolide) (PLGA) polymer solution, which was electrospun to prepare PLGA/nHA-I composite nanofiber scaffolds. The morphology of the electrospun nanofiber scaffolds was assessed by field emission scanning electron microscopy (FESEM). After extensive characterization of the PLGA/nHA-I and PLGA/nHA composite nanofiber scaffolds by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM), the PLGA/nHA-I and PLGA/nHA (used as control) composite nanofiber scaffolds were subjected to cell studies. The results obtained from cell adhesion, alizarin red staining, and Von Kossa assay suggested that the PLGA/nHA-I composite nanofiber scaffold has enhanced osteoblastic cell growth, as more cells were proliferated and differentiated. The fact that insulin enhanced osteoblastic cell proliferation will open new possibilities for the development of artificial scaffolds for bone tissue regeneration.

  16. Characterization of mechanical properties of hydroxyapatite-silicon-multi walled carbon nano tubes composite coatings synthesized by EPD on NiTi alloys for biomedical application.

    PubMed

    Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred

    2016-06-01

    Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application.

  17. Synthesis and characterization of nano-hydroxyapatite in maltodextrin matrix

    NASA Astrophysics Data System (ADS)

    Phan, Bich T. N.; Nguyen, Hanh T.; Đao, Huong Q.; Pham, Lam V.; Quan, Trang T. T.; Nguyen, Duong B.; Nguyen, Huong T. L.; Vu, Thuan T.

    2017-02-01

    In this study, we report the direct precipitation of nano-HA in the present of maltodextrins with the different dextrose equivalent (DE) values in the range of 10-30. Characterization of the obtained samples, using X-ray diffraction and Fourier transform infrared spectrophotometry, indicated that the presence of maltodextrins, with the different DE values, does not affect the phase composition and structure of the obtained composites. Morphology studies of the samples, using field emission scanning electron microscope and transmission electron microscope, revealed that maltodextrin has obvious effect on the size, shape, and morphology of hydroxyapatite nanoparticles. In particular, in studied DE range, maltodextrin DE 28-30 with dominant structure of debranched chain is the most preferable choice to obtain the composite with highly dispersed nanoparticles. In vitro assay on pre-osteoblast MC3T3-E1 cells demonstrated the ability of the composites to stimulate alkaline phosphatase activity and mineralization during differentiation of the cells.

  18. Synthesis and characterization of nano-hydroxyapatite in maltodextrin matrix

    NASA Astrophysics Data System (ADS)

    Phan, Bich T. N.; Nguyen, Hanh T.; Đao, Huong Q.; Pham, Lam V.; Quan, Trang T. T.; Nguyen, Duong B.; Nguyen, Huong T. L.; Vu, Thuan T.

    2016-11-01

    In this study, we report the direct precipitation of nano-HA in the present of maltodextrins with the different dextrose equivalent (DE) values in the range of 10-30. Characterization of the obtained samples, using X-ray diffraction and Fourier transform infrared spectrophotometry, indicated that the presence of maltodextrins, with the different DE values, does not affect the phase composition and structure of the obtained composites. Morphology studies of the samples, using field emission scanning electron microscope and transmission electron microscope, revealed that maltodextrin has obvious effect on the size, shape, and morphology of hydroxyapatite nanoparticles. In particular, in studied DE range, maltodextrin DE 28-30 with dominant structure of debranched chain is the most preferable choice to obtain the composite with highly dispersed nanoparticles. In vitro assay on pre-osteoblast MC3T3-E1 cells demonstrated the ability of the composites to stimulate alkaline phosphatase activity and mineralization during differentiation of the cells.

  19. Robocasting nanocomposite scaffolds of poly(caprolactone)/hydroxyapatite incorporating modified carbon nanotubes for hard tissue reconstruction.

    PubMed

    Dorj, Biligzaya; Won, Jong-Eun; Kim, Joong-Hyun; Choi, Seong-Jun; Shin, Ueon Sang; Kim, Hae-Won

    2013-06-01

    Nanocomposite scaffolds with tailored 3D pore configuration are promising candidates for the reconstruction of bone. Here we fabricated novel nanocomposite bone scaffolds through robocasting. Poly(caprolactone) (PCL)-hydroxyapatite (HA) slurry containing ionically modified carbon nanotubes (imCNTs) was robotic-dispensed and structured layer-by-layer into macrochanneled 3D scaffolds under adjusted processing conditions. Homogeneous dispersion of imCNTs (0.2 wt % relative to PCL-HA) was achieved in acetone, aiding in the preparation of PCL-HA-imCNTs slurry with good mixing property. Incorporation of imCNTs into PCL-HA composition significantly improved the compressive strength and elastic modulus of the robotic-dispensed scaffolds (~1.5-fold in strength and ~2.5-fold in elastic modulus). When incubated in simulated body fluid (SBF), PCL-HA-imCNT nanocomposite scaffold induced substantial mineralization of apatite in a similar manner to the PCL-HA scaffold, which was contrasted in pure PCL scaffold. MC3T3-E1 cell culture on the scaffolds demonstrated that cell proliferation levels were significantly higher in both PCL-HA-imCNT and PCL-HA than in pure PCL, and no significant difference was found between the nanocomposite scaffolds. When the PCL-HA-imCNT scaffold was implanted into a rat subcutaneous tissue for 4 weeks, soft fibrous tissues with neo-blood vessels formed well in the pore channels of the scaffolds without any significant inflammatory signs. Tissue reactions in PCL-HA-imCNT scaffold were similar to those in PCL-HA scaffold, suggesting incorporated imCNT did not negate the beneficial biological roles of HA. While more long-term in vivo research in bone defect models is needed to confirm clinical availability, our results suggest robotic-dispensed PCL-HA-imCNT nanocomposite scaffolds can be considered promising new candidate matrices for bone regeneration.

  20. Induction plasma sprayed Sr and Mg doped nano hydroxyapatite coatings on Ti for bone implant.

    PubMed

    Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2011-11-01

    In this study, we report fabrication of strontium (Sr) and magnesium (Mg) doped hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) substrates using inductively coupled radio frequency (RF) plasma spray. HA powder was doped with 1 wt % Sr (Sr-HA) and 1 wt % Mg (Mg-HA), heat treated at 800°C for 6 h and then used for plasma spray coating. X-ray diffraction (XRD) and Fourier transformed infrared spectroscopic (FTIR) analysis indicated that the coatings were primarily composed of phase pure crystalline HA. When compared to undoped HA coating, physical properties such as microstructure, grain size, and adhesive bond strength of the doped HA coatings did not change significantly. Microstructure of the coatings showed coherency in the structure with an average grain size of 200-280 μm HA particles, where each of the HA grains consisted of 20-30 nm sized particles. An average adhesive bond strength of 17 MPa ensured sufficient mechanical strength of the coatings. A chemistry dependent improvement in bone cell-coating interaction was noticed for doped coatings although it had minimal effect on physical properties of the coatings. In vitro cell-materials interactions using human fetal osteoblasts (hFOB) showed better cell attachment and proliferation on Sr-HA coatings compared to HA or Mg-HA coatings. Presence of Sr in the coating also stimulated hFOB cell differentiation and alkaline phosphatase (ALP) expression. Improvement in bioactivity of Sr doped HA coatings on Ti without compromising its mechanical properties makes it an excellent material of choice for coated implant.

  1. Polarization and microstructural effects of ceramic hydroxyapatite electrets

    NASA Astrophysics Data System (ADS)

    Tanaka, Yumi; Iwasaki, Takeshi; Nakamura, Miho; Nagai, Akiko; Katayama, Keiichi; Yamashita, Kimihiro

    2010-01-01

    To provide bioelectrets with controlled electrical energy, the polarization and relaxation characteristics of hydroxyapatite (HA) ceramic electrets were investigated in terms of poling conditions and microstructures. HA electrets were prepared between 250 and 500 °C for 5-120 min under a 5 kV cm-1 dc electrical field. Poling conditions and grain size of HA ceramics significantly influenced the thermally stimulated depolarization current (TSDC) spectra and charge storage (Q). Under a poling field of 5 kV cm-1, varying the poling temperature from 250 to 500 °C drastically shifted the TSDC peak temperature from 250 to 620 °C and increased Q from 0.5 to 45 μC cm-2. The change in the average grain size from 2 to 11 μm increased the Q value from 15 to 60 μC cm-2 with a negligible shift in the TSDC peak position. The measured difference of the TSDC peak shapes and positions, as well as the Q values, was theoretically due to the four polarization states with different activation energies (Edr) of dipole relaxation and the pre-exponential factor of relaxation times (τ0). The dependences on the poling conditions and grain size indicated that the four states were due to the orientation polarization of absorbed water (state 1), the localizations of displaced protons around PO43- and OH- in the grains (states 2 and 3), and the localization of displaced protons in the grain boundaries (state 4).

  2. Fretting wear behaviour of hydroxyapatite-titanium composites in simulated body fluid, supplemented with 5 g l-1 bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Kumar, Alok; Biswas, Krishanu; Basu, Bikramjit

    2013-10-01

    Damaged articulating joints can be repaired or replaced with synthetic biomaterials, which can release wear debris due to articulation, leading to the osteolysis. In a recent work, it has been shown that it is possible to achieve a better combination of flexural strength/fracture toughness as well as in vitro bioactivity and cytocompatibility properties in spark plasma sintered hydroxyapatite-titanium (HA-Ti) composites. Although hydroxyapatite and titanium are well documented for their good biocompatibility, nanosized hydroxyapatite (HA) and titanium (Ti) particles can cause severe toxicity to cells. In order to address this issue, fretting wear study of HA-Ti composites under dry and wet (1× SBF, supplemented with 5 g l-1 bovine serum albumin (BSA)) condition was performed to assess the wear resistance as well as wear debris formation, in vitro. The experimental results reveal one order of magnitude lower wear rate for HA-10 wt% Ti (7.5 × 10-5 mm3 N-1 m-1) composite than monolithic HA (3.9 × 10-4 mm3 N-1 m-1) in simulated body fluid. The difference in the tribological properties has been analyzed in the light of phase assemblages and mechanical properties. Overall, the results suggest the potential use of HA-Ti composites over existing HA-based biocomposites in orthopedic as well as dental applications.

  3. Microwave assisted synthesis of nano sized sulphate doped hydroxyapatite

    SciTech Connect

    Alshemary, Ammar Z.; Goh, Yi-Fan; Akram, Muhammad; Razali, Ili Rabihah; Abdul Kadir, Mohammed Rafiq; Hussain, Rafaqat

    2013-06-01

    Highlights: ► Phase pure nano-sized sulphur doped hydroxyapatite has been synthesized. ► TEM analysis confirmed formation of needle shaped structure. ► Lattice parameters and cell volume increased with increase in sulphate doping. ► Crystallite size decreased as sulphate content inside the structure increased. ► Degree of crystallinity decreased with increase in sulphate substitution. - Abstract: Inorganic sulphate is required by all mammalian cells to function properly, it is the fourth most abundant anion in the human plasma. Sulphate ions are the major source of sulphur which is considered an important element for sustenance of life as it is present in the essential amino and is required by cells to function properly. In this study we have successfully substituted sulphate ions (SO{sub 4}{sup 2−}) into hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6−x}(SO{sub 4}){sub x}(OH){sub 2−x}) lattice via ion exchange process with phosphate group. Concentration of SO{sub 4}{sup 2−} ions was varied between X = 0.05–0.5, using (Ca (NO{sub 3}){sub 2}·4H{sub 2}O), ((NH{sub 4}){sub 2}HPO{sub 4}) and (Na{sub 2}SO{sub 4}) as starting materials. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), showed that the substitution of SO{sub 4}{sup 2−} ions into the lattice resulted in peak broadening and reduced peak height due to the amorphous nature and reduced crystallinity of the resulting HA powder. Transmission electron microscopy (TEM) and field emission electron microscopy (FESEM) analysis confirmed the formation of needle shaped particles of 41 nm size with homogenous and uniform distribution of element within the HA structure.

  4. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of

  5. Study the bonding mechanism of binders on hydroxyapatite surface and mechanical properties for 3DP fabrication bone scaffolds.

    PubMed

    Wei, Qinghua; Wang, Yanen; Li, Xinpei; Yang, Mingming; Chai, Weihong; Wang, Kai; zhang, Yingfeng

    2016-04-01

    In 3DP fabricating artificial bone scaffolds process, the interaction mechanism between binder and bioceramics power determines the microstructure and macro mechanical properties of Hydroxyapatite (HA) bone scaffold. In this study, we applied Molecular Dynamics (MD) methods to investigating the bonding mechanism and essence of binders on the HA crystallographic planes for 3DP fabrication bone scaffolds. The cohesive energy densities of binders and the binding energies, PCFs g(r), mechanical properties of binder/HA interaction models were analyzed through the MD simulation. Additionally, we prepared the HA bone scaffold specimens with different glues by 3DP additive manufacturing, and tested their mechanical properties by the electronic universal testing machine. The simulation results revealed that the relationship of the binding energies between binders and HA surface is consistent with the cohesive energy densities of binders, which is PAM/HA>PVA/HA>PVP/HA. The PCFs g(r) indicated that their interfacial interactions mainly attribute to the ionic bonds and hydrogen bonds which formed between the polar atoms, functional groups in binder polymer and the Ca, -OH in HA. The results of mechanical experiments verified the relationship of Young׳s modulus for three interaction models in simulation, which is PVA/HA>PAM/HA>PVP/HA. But the trend of compressive strength is PAM/HA>PVA/HA>PVP/HA, this is consistent with the binding energies of simulation. Therefore, the Young׳s modulus of bone scaffolds are limited by the Young׳s modulus of binders, and the compressive strength is mainly decided by the viscosity of binder. Finally, the major reasons for differences in mechanical properties between simulation and experiment were found, the space among HA pellets and the incomplete infiltration of glue were the main reasons influencing the mechanical properties of 3DP fabrication HA bone scaffolds. These results provide useful information in choosing binder for 3DP fabrication

  6. Electrospun polyurethane/hydroxyapatite bioactive scaffolds for bone tissue engineering: the role of solvent and hydroxyapatite particles.

    PubMed

    Tetteh, G; Khan, A S; Delaine-Smith, R M; Reilly, G C; Rehman, I U

    2014-11-01

    Polyurethane (PU) is a promising polymer to support bone-matrix producing cells due to its durability and mechanical resistance. In this study two types of medical grade poly-ether urethanes Z3A1 and Z9A1 and PU-Hydroxyapatite (PU-HA) composites were investigated for their ability to act as a scaffold for tissue engineered bone. PU dissolved in varying concentrations of dimethylformamide (DMF) and tetrahydrofuran (THF) solvents were electrospun to attain scaffolds with randomly orientated non-woven fibres. Bioactive polymeric composite scaffolds were created using 15 wt% Z3A1 in a 70/30 DMF/THF PU solution and incorporating micro- or nano-sized HA particles in a ratio of 3:1 respectively, whilst a 25 wt% Z9A1 PU solution was doped in ratio of 5:1. Chemical properties of the resulting composites were evaluated by FTIR and physical properties by SEM. Tensile mechanical testing was carried out on all electrospun scaffolds. MLO-A5 osteoblastic mouse cells and human embryonic mesenchymal progenitor cells, hES-MPs were seeded on the scaffolds to test their biocompatibility and ability to support mineralised matrix production over a 28 day culture period. Cell viability was assayed by MTT and calcium and collagen deposition by Sirius red and alizarin red respectively. SEM images of both electrospun PU scaffolds and PU-HA composite scaffolds showed differences in fibre morphology with changes in solvent combinations and size of HA particles. Inclusion of THF eliminated the presence of beads in fibres that were present in scaffolds fabricated with 100% DMF solvent, and resulted in fibres with a more uniform morphology and thicker diameters. Mechanical testing demonstrated that the Young׳s Modulus and yield strength was lower at higher THF concentrations. Inclusion of both sizes of HA particles in PU-HA solutions reinforced the scaffolds leading to higher mechanical properties, whilst FTIR characterisation confirmed the presence of HA in all composite scaffolds. Although

  7. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Trace microsphere. 870.1360 Section 870.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... and Drug Administration on or before December 26, 1996 for any trace microsphere that was...

  8. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Trace microsphere. 870.1360 Section 870.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... and Drug Administration on or before December 26, 1996 for any trace microsphere that was...

  9. Flow cytometry analysis of human fetal osteoblast fate processes on spark plasma sintered hydroxyapatite-titanium biocomposites.

    PubMed

    Kumar, Alok; Webster, Thomas J; Biswas, Krishanu; Basu, Bikramjit

    2013-10-01

    Hydroxyapatite (HA)-based biocomposites have been widely investigated for a multitude of applications and these studies have been largely driven to improve mechanical properties (toughness and strength) without compromising cytocompatibility properties. Apart from routine cell viability/proliferation analysis, limited efforts have been made to quantify the fate processes (cell proliferation, cell cycle, and cell apoptosis) of human fetal osteoblast (hFOB) cells on HA-based composites, in vitro. In this work, the osteoblast cell fate process has been studied on a model hydroxyapatite-titanium (HA-Ti) system using the flow cytometry. In order to retain both HA and Ti, the novel processing technique, that is, spark plasma sintering, was suitably adopted. The cell fate processes of hFOBs, as evaluated using a flow cytometry, revealed statistically insignificant differences among HA-10 wt % Ti and HA and control (tissue culture polystyrene surface) in terms of osteoblast apoptosis, proliferation index as well as division index. For the first time, we provide quantified flow cytometry results to demonstrate that 10 wt % Ti additions to HA do not have any significant influence on the fate processes of human osteoblast-like cells, in vitro.

  10. Enhanced osteoconductivity of sodium-substituted hydroxyapatite by system instability.

    PubMed

    Sang Cho, Jung; Um, Seung-Hoon; Su Yoo, Dong; Chung, Yong-Chae; Hye Chung, Shin; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2014-07-01

    The effect of substituting sodium for calcium on enhanced osteoconductivity of hydroxyapatite was newly investigated. Sodium-substituted hydroxyapatite was synthesized by reacting calcium hydroxide and phosphoric acid with sodium nitrate followed by sintering. As a control, pure hydroxyapatite was prepared under identical conditions, but without the addition of sodium nitrate. Substitution of calcium with sodium in hydroxyapatite produced the structural vacancies for carbonate ion from phosphate site and hydrogen ion from hydroxide site of hydroxyapatite after sintering. The total system energy of sodium-substituted hydroxyapatite with structural defects calculated by ab initio methods based on quantum mechanics was much higher than that of hydroxyapatite, suggesting that the sodium-substituted hydroxyapatite was energetically less stable compared with hydroxyapatite. Indeed, sodium-substituted hydroxyapatite exhibited higher dissolution behavior of constituent elements of hydroxyapatite in simulated body fluid (SBF) and Tris-buffered deionized water compared with hydroxyapatite, which directly affected low-crystalline hydroxyl-carbonate apatite forming capacity by increasing the degree of apatite supersaturation in SBF. Actually, sodium-substituted hydroxyapatite exhibited markedly improved low-crystalline hydroxyl-carbonate apatite forming capacity in SBF and noticeably higher osteoconductivity 4 weeks after implantation in calvarial defects of New Zealand white rabbits compared with hydroxyapatite. In addition, there were no statistically significant differences between hydroxyapatite and sodium-substituted hydroxyapatite on cytotoxicity as determined by BCA assay. Taken together, these results indicate that sodium-substituted hydroxyapatite with structural defects has promising potential for use as a bone grafting material due to its enhanced osteoconductivity compared with hydroxyapatite.

  11. Synthesis of chitosan/hydroxyapatite membranes coated with hydroxycarbonate apatite for guided tissue regeneration purposes

    NASA Astrophysics Data System (ADS)

    Fraga, Alexandre Félix; Filho, Edson de Almeida; Rigo, Eliana Cristina da Silva; Boschi, Anselmo Ortega

    2011-02-01

    Chitosan, which is a non-toxic, biodegradable and biocompatible biopolymer, has been widely researched for several applications in the field of biomaterials. Calcium phosphate ceramics stand out among the so-called bioceramics for their absence of local or systemic toxicity, their non-response to foreign bodies or inflammations, and their apparent ability to bond to the host tissue. Hydroxyapatite (HA) is one of the most important bioceramics because it is the main component of the mineral phase of bone. The aim of this work was to produce chitosan membranes coated with hydroxyapatite using the modified biomimetic method. Membranes were synthesized from a solution containing 2% of chitosan in acetic acid (weight/volume) via the solvent evaporation method. Specimens were immersed in a sodium silicate solution and then in a 1.5 SBF (simulated body fluid) solution. The crystallinity of the HA formed over the membranes was correlated to the use of the nucleation agent (the sodium silicate solution itself). Coated membranes were characterized by means of scanning electron microscopy - SEM, X-ray diffraction - XRD, and Fourier transform infrared spectroscopy - FTIR. The results indicate a homogeneous coating covering the entire surface of the membrane and the production of a semi-crystalline hydroxyapatite layer similar to the mineral phase of human bone.

  12. Synthesis, bioactivity and zeta potential investigations of chlorine and fluorine substituted hydroxyapatite.

    PubMed

    Fahami, Abbas; Beall, Gary W; Betancourt, Tania

    2016-02-01

    Chlorine and fluorine substituted hydroxyapatites (HA-Cl-F) with different degrees of ion replacement were successfully prepared by the one step mechanochemical activation method. X-ray diffraction (XRD) and FT-IR spectra indicated that substitution of these anions in milled powders resulted in the formation of pure hydroxyapatite phase except for the small observed change in the lattice parameters and unit cell volumes of the resultant hydroxyapatite. Microscopic observations showed that the milled product had a cluster-like structure made up of polygonal and spherical particles with an average particle size of approximately ranged from 20±5 to 70±5nm. The zeta potential of milled samples was performed at three different pH (5, 7.4, and 9). The obtained zeta potential values were negative for all three pH values. Negative zeta potential was described to favor osseointegration, apatite nucleation, and bone regeneration. The bioactivity of samples was investigated on sintered pellets soaked in simulated body fluid (SBF) solution and apatite crystals formed on the surface of the pellets after being incubated for 14days. Zeta potential analysis and bioactivity experiment suggested that HA-Cl-F will lead to the formation of new apatite particles and therefore be a potential implant material.

  13. Preparation and characterization of NiW-nHA composite catalyst for hydrocracking

    NASA Astrophysics Data System (ADS)

    Zhou, Gang; Hou, Yongzhao; Liu, Lei; Liu, Hongru; Liu, Can; Liu, Jing; Qiao, Huiting; Liu, Wenyong; Fan, Yubo; Shen, Shituan; Rong, Long

    2012-11-01

    The synthesis, characterization and catalytic capability of the NiW-nano-hydroxyapatite (NiW-nHA) composite were investigated in this paper. The NiW-nHA catalyst was prepared by a co-precipitation method. Then Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDX) were used to analyze this material. In addition, the catalytic capacity of the NiW-nHA composite was also examined by FT-IR and gas chromatography (GC). The results of FT-IR analysis indicated that Ni, W and nHA combined closely. TEM observation revealed that this catalyst was needle shaped and the crystal retained a nanometer size. XRD data also suggested that a new phase of CaWO4 appeared and the lattice parameters of nHA changed in this system. nHA was the carrier of metals. The rates of Ni/W-loading were 73.24% and 65.99% according to the EDX data, respectively. Furthermore, the conversion of 91.88% Jatropha oil was achieved at 360 °C and 3 MPa h-1 over NiW-nHA catalyst. The straight chain alkanes ranging from C15 to C18 were the main components in the production. The yield of C15-C18 alkanes was up to 83.56 wt%. The reaction pathway involved hydrocracking of the C&z.dbd;C bonds of these triglycerides from Jatropha oil. This paper developed a novel non-sulfided catalyst to obtain a ``green biofuel'' from vegetable oil.

  14. Spectral analysis of allogeneic hydroxyapatite powders

    NASA Astrophysics Data System (ADS)

    Timchenko, P. E.; Timchenko, E. V.; Pisareva, E. V.; Vlasov, M. Yu; Red’kin, N. A.; Frolov, O. O.

    2017-01-01

    In this paper we discuss the application of Raman spectroscopy to the in vitro analysis of the hydroxyapatite powder samples produced from different types of animal bone tissue during demineralization process at various acid concentrations and exposure durations. The derivation of the Raman spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constituents. Were experimentally found spectral features of hydroxyapatite, based on analysis of the line amplitude at wave numbers 950-965 cm-1 ((PO4)3- (ν1) vibration) and 1065-1075 cm-1 ((CO3)2-(ν1) B-type replacement). Control of physicochemical properties of hydroxyapatite was carried out by Raman spectroscopy. Research results are compared with an infrared Fourier spectroscopy.

  15. Integrated Cryogenic Experiment (ICE) microsphere investigation

    NASA Astrophysics Data System (ADS)

    Spradley, I.; Read, D.

    1989-09-01

    The main objective is to determine the performance of microsphere insulation in a 0-g environment and compare its performance to reference insulations such as multilayer insulation. The Lockheed Helium Extended-Life Dewar (HELD) is used to provide superfluid-helium cold sink for the experiment. The use of HELD allows the low-g dynamic properties of Passive Orbital Disconnect Struts (PODS) to be characterized and provides a flight demonstration of the PODS system. The thermal performance of microspheres in 1 and 0 g was predicted, a flight experiment was designed to determine microsphere thermal performance, and the interface was also designed between the experimental package and the shuttle through HELD and the Hitchhiker-M carrier. A single test cell was designed and fabricated. The cell was filled with uncoated glass microspheres and tested with a liquid-nitrogen cold sink. The data were found to agree with predictions of microsphere performance in 1 g.

  16. Nanostructural characteristics, mechanical properties, and osteoblast response of spark plasma sintered hydroxyapatite.

    PubMed

    Li, H; Khor, K A; Chow, V; Cheang, P

    2007-08-01

    This study aimed to fabricate bulk nanostructured hydroxyapatite (HA) pellets with improved properties using spark plasma sintering (SPS) for orthopedic applications. Spray-dried nanostructured HA (nSD-HA) powders were consolidated using the rapid SPS processing. The SPS processed nSD-HA was characterized using Raman spectroscopy and field emission scanning electron microscopy (FESEM). Mechanical properties of the consolidates were also evaluated through indentation approach. The nanostructures ( approximately 80 nm in grain size) of the starting powders were successfully retained after the SPS processing operated at 950 degrees C with <15 min holding time. The SPS consolidated nSD-HA showed promising mechanical properties, approximately 118 GPa for Young's modulus, and up to 2.22 MPa m(0.5) for fracture toughness. SPS holding time showed minor influence on the phases of the pellets. Furthermore, the spheroidized nanostructured HA retained the HA structure after the SPS consolidation. Preliminary cytotoxicity and cell attachment studies were also carried out using a human osteoblast cell line hFOB 1.19. Enhanced cell attachment and proliferation on the nanostructured pellets were revealed. The presence of the nanostructures accounts mainly for the enhanced mechanical properties and promoted proliferation of the osteoblast cells. This study suggests that the SPS technique is an appropriate process for fabrication of bulk nSD-HA from nanostructured powder.

  17. In vivo study on hydroxyapatite scaffolds with trabecular architecture for bone repair.

    PubMed

    Appleford, Mark R; Oh, Sunho; Oh, Namsik; Ong, Joo L

    2009-06-15

    The objective of this research was to investigate the bone formation and angio-conductive potential of hydroxyapatite (HA) scaffolds closely matched to trabecular bone in a canine segmental defect after 3 and 12 weeks post implantation. Histomorphometric comparisons were made between naturally forming trabecular bone (control) and defects implanted with scaffolds fabricated with micro-size (M-HA) and nano-size HA (N-HA) ceramic surfaces. Scaffold architecture was similar to trabecular bone formed in control defects at 3 weeks. No significant differences were identified between the two HA scaffolds; however, significant bone in-growth was observed by 12 weeks with 43.9 +/- 4.1% and 50.4 +/- 8.8% of the cross-sectional area filled with mineralized bone in M-HA and N-HA scaffolds, respectively. Partially organized, lamellar collagen fibrils were identified by birefringence under cross-polarized light at both 3 and 12 weeks post implantation. Substantial blood vessel infiltration was identified in the scaffolds and compared with the distribution and diameter of vessels in the surrounding cortical bone. Vessels were less numerous but significantly larger than native cortical Haversian and Volkmann canals reflecting the scaffold architecture where open spaces allowed interconnected channels of bone to form. This study demonstrated the potential of trabecular bone modeled, highly porous and interconnected, HA scaffolds for regenerative orthopedics.

  18. Preparation and Characterization of Lanthanum-Incorporated Hydroxyapatite Coatings on Titanium Substrates

    PubMed Central

    Lou, Weiwei; Dong, Yiwen; Zhang, Hualin; Jin, Yifan; Hu, Xiaohui; Ma, Jianfeng; Liu, Jinsong; Wu, Gang

    2015-01-01

    Titanium (Ti) has been widely used in clinical applications for its excellent biocompatibility and mechanical properties. However, the bioinertness of the surface of Ti has motivated researchers to improve the physicochemical and biological properties of the implants through various surface modifications, such as coatings. For this purpose, we prepared a novel bioactive material, a lanthanum-incorporated hydroxyapatite (La-HA) coating, using a dip-coating technique with a La-HA sol along with post-heat treatment. The XRD, FTIR and EDX results presented in this paper confirmed that lanthanum was successfully incorporated into the structure of HA. The La-HA coating was composed of rod-like particles which densely compacted together without microcracks. The results of the interfacial shear strength test indicated that the incorporation of lanthanum increased the bonding strength of the HA coating. The mass loss ratios under acidic conditions (pH = 5.5) suggested that the La-HA coatings have better acid resistance. The cytocompatibility of the La-HA coating was also revealed by the relative activity of alkaline phosphatase, cellular morphology and cell proliferation assay in vitro. The present study suggested that La-HA coated on Ti has promising potential for applications in the development of a new type of bioactive coating for metal implants. PMID:26404255

  19. Osteoblastic cell attachment to hydroxyapatite-coated implant surfaces in vitro.

    PubMed

    Chang, Y L; Stanford, C M; Wefel, J S; Keller, J C

    1999-01-01

    Hydroxyapatite (HA) used as a coating for implants can exhibit varying levels of interaction with the biologic environment. The crystallinity of the HA-based coating has been shown to control the rate of dissolution and appears to play a role in the initial cellular interaction with the implant surfaces. An osteoblastic cell attachment assay was employed to examine the cell attachment to untreated and pretreated (pH 5.2, 24 hours) titanium and HA coatings of low (50%), medium (75%), and high (90%) crystallinity. A slightly higher percentage of cell attachment (%CA) was found on untreated and pretreated HA surfaces as compared to the titanium surface. No significant difference could be found in the %CA between the 3 levels of crystallinity. However, higher levels of %CA were observed on pretreated HA surfaces than on untreated HA surfaces (t test, P < .05). Elevated calcium and phosphate levels in culture medium did not have any effect on cell attachment. Scanning electron microscopic examinations revealed surface degradation of the HA coating following pretreatment in the simulated inflammatory media (pH 5.2, 24 hours). The results suggest that the altered surface topography may influence the initial cell attachment to HA surfaces.

  20. Synthesis, characterization and modelling of zinc and silicate co-substituted hydroxyapatite

    PubMed Central

    Friederichs, Robert J.; Chappell, Helen F.; Shepherd, David V.; Best, Serena M.

    2015-01-01

    Experimental chemistry and atomic modelling studies were performed here to investigate a novel ionic co-substitution in hydroxyapatite (HA). Zinc, silicate co-substituted HA (ZnSiHA) remained phase pure after heating to 1100°C with Zn and Si amounts of 0.6 wt% and 1.2 wt%, respectively. Unique lattice expansions in ZnSiHA, silicate Fourier transform infrared peaks and changes to the hydroxyl IR stretching region suggested Zn and silicate co-substitution in ZnSiHA. Zn and silicate insertion into HA was modelled using density functional theory (DFT). Different scenarios were considered where Zn substituted for different calcium sites or at a 2b site along the c-axis, which was suspected in singly substituted ZnHA. The most energetically favourable site in ZnSiHA was Zn positioned at a previously unreported interstitial site just off the c-axis near a silicate tetrahedron sitting on a phosphate site. A combination of experimental chemistry and DFT modelling provided insight into these complex co-substituted calcium phosphates that could find biomedical application as a synthetic bone mineral substitute. PMID:26040597

  1. Covalent bonding of PMMA, PBMA, and poly(HEMA)to hydroxyapatite particles.

    PubMed

    Liu, Q; de Wijn, J R; van Blitterswijk, C A

    1998-05-01

    In our earlier study, we showed that the surface hydroxyl groups of hydroxyapatite have the ability to react with organic isocyanate groups. In this study, the feasibility of grafting poly(methyl methacrylate) (PMMA), poly(n-butyl methacrylate) (PBMA), and Poly(hydroxyethyl methacrylate) [poly(HEMA)] by using the reaction of isocyanate groups with the hydroxyl groups on the surface of HA was investigated. Double bonds were introduced to the surface of HA via the coupling reaction of isocyanateoethyl methacrylate (ICEM) with HA, or through hexamethylene diisocyanate (HMDI) with hydroxyethyl methacrylate (HEMA) and HA, followed by radical polymerization in MMA, BMA, or HEMA. Infrared spectra indicated the existence of polymers on the surfaces of HA. Thermogravimetric analysis also confirmed the presence of grafted polymers on the surface of HA powder particles (20-26 wt%). The polymers gave typical PMMA, PBMA, or poly(HEMA) infrared spectra, with the exception of amide bands, a result of the coupling reaction of ICEM or HMDI with hydroxy groups of HA or HEMA. Therefore it is concluded that the polymers were chemically bonded to the surface of HA through the isocyanate groups of ICEM or HMDI.

  2. Hydroxyapatite coatings with oriented nanoplate and nanorod arrays: Fabrication, morphology, cytocompatibility and osteogenic differentiation.

    PubMed

    Chen, Wei; Tian, Bo; Lei, Yong; Ke, Qin-Fei; Zhu, Zhen-An; Guo, Ya-Ping

    2016-10-01

    Hydroxyapatite (HA) crystals exhibit rod-like shape with c-axis orientation and plate-like shape with a(b)-axis orientation in vertebrate bones and tooth enamel surfaces, respectively. Herein, we report the synthesis of HA coatings with the oriented nanorod arrays (RHACs) and HA coatings with oriented nanoplate arrays (PHACs) by using bioglass coatings as sacrificial templates. After soaking in simulated body fluid (SBF) at 120°C, the bioglass coatings are hydrothermally converted into the HA coatings via a dissolution-precipitation reaction. If the Ca/P ratios in SBF are 2.50 and 1.25, the HA crystals on the coatings are oriented nanorod arrays and oriented nanoplate arrays, respectively. Moreover, the bioglass coatings are treated with SBF at 37°C, plate-like HA coatings with a low crystallinity (SHACs) are prepared. As compared with the Ti6Al4V and SHACs, the human bone marrow stromal cells (hBMSCs) on the RHACs and PHACs have better cell adhesion, spreading, proliferation and osteogenic differentiation because of their moderately hydrophilic surfaces and similar chemical composition, morphology and crystal orientation to human hard tissues. Notably, the morphologies of HA crystals have no obvious effects on cytocompatibility and osteogenic differentiation. Hence, the HA coatings with oriented nanoplate arrays or oriented nanorod arrays have a great potential for orthopedic applications.

  3. Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

    NASA Astrophysics Data System (ADS)

    Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

    2015-08-01

    Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

  4. Evaluation of nanoparticles of hydroxyapatite and MWCNT’s in scaffolds of poly lactic acid

    NASA Astrophysics Data System (ADS)

    Román-Doval, R.; Morales-Corona, J.; Olayo, R.; Escamilla-Rivera, V.; Uribe-Ramírez, M.; Ortega-López, M.

    2016-12-01

    In the tissue engineering, the cytotoxicity test is an important part of the biomaterials performance. This research reports the production and characterization of polylactic acid (PLA)-supported hydroxyapatite (HA) and multiwalled carbon nanotubes (MWCNT) scaffolds as a bone graft material. Samples containing different HA/MWCNT wt% ratios were prepared by electrospinning. The obtained samples displayed valuable characteristics for the cell adhesion because of their porous-spongy bone-like morphology. The Fourier transforms infrared and Raman analyses indicated no chemical interaction of HA and MWCNT with PLA molecules, but they appear to be only embedded into the PLA fibers. As indicated by x-ray diffraction, crystalline HA and MWCNT’s are supported in the amorphous PLA fibers. Under tensile stress, scaffolds display a Young’s Modulus about 86 MPa, whilst the scaffolds resistance increases with the HA-MWCNT’s ratio. However, the MTS in-vitro assays using the hFOB 1.19 (ATCC CRL-11372) cells, for cell exposure time of 24 and 48 h, revealed that viability reduces for HA-MWCNT’s ratio values over 25 wt%. Our results suggest that a maximum HA/MWCNT’s ratio of 19:1 could be acceptable for cell proliferation while maintaining HA at 200 mg.

  5. Silver/hydroxyapatite composite coatings on porous titanium surfaces by sol-gel method.

    PubMed

    Qu, Jie; Lu, Xiong; Li, Dan; Ding, Yonghui; Leng, Yang; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio

    2011-04-01

    Hydroxyapatite (HA) coatings loaded with nanosilver particles is an attractive method to impart the HA coating with antibacterial properties. Producing Ag/HA coatings on porous Ti substrates have been an arduous job since commonly used line-of-sight techniques are not able to deposit uniform coatings on the inner pore surfaces of the porous Ti. In this study, porous Ti scaffolds with high porosity and interconnected structures were prepared by polymer impregnating method. A sol-gel process was used to produce uniform Ag/HA composite coatings on the surfaces of porous Ti substrates. Ca(NO(3) )(2) ·4H(2) O and P(2) O(5) in an ethyl alcohol based system was selected to prepare the sol, which ensured the homogeneous distribution of Ag in the sol. The characterization revealed that silver particles uniformly distributed in the coatings without agglomeration. High antibacterial ratio (>95%), against E. coli and S. albus was expressed by the silver-containing coatings (Ag/HA 0.8 and 1.6 wt %). The biocompatibility of the Ag/HA 0.8 surfaces was as good as that of pure HA surface, as revealed by culturing osteoblasts on them. The results indicated that Ag/HA 0.8 had the good balance between the biocompatibility and antibacterial properties of the coatings.

  6. Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites.

    PubMed

    Shen, Lie; Yang, Hui; Ying, Jia; Qiao, Fei; Peng, Mao

    2009-11-01

    A novel biocomposite of carbon fiber (CF) reinforced hydroxyapatite (HA)/polylactide (PLA) was prepared by hot pressing a prepreg which consisting of PLA, HA and CF. The prepreg was manufactured by solvent impregnation process. Polymer resin PLA dissolved with chloroform was mixed with HA. After reinforcement CF bundle was impregnated in the mixture, the solvent was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 170 degrees C for 20 min. A study was carried out to investigate change in mechanical properties of CF/HA/PLA composites before and after degradation in vitro. The composites have excellent mechanical properties. A peak showed in flexural strength, flexural modulus and shear strength aspects, reaching up 430 MPa, 22 GPa, 212 MPa, respectively, as the HA content increased. Degraded in vitro for 3 months, the flexural strength and flexural modulus of the CF/HA/PLA fell 13.2% and 5.4%, respectively, while the shear strength of the CF/HA/PLA composites remains at the 190 MPa level. The SEM photos showed that there were gaps between the PLA matrix and CF after degradation. Water uptake increased to 5%, but the mass loss rate was only 1.6%. The pH values of the PBS dropped less than 0.1. That's because the alkaline of HA neutralize the acid degrades from PLA, which can prevent the body from the acidity harm.

  7. In vitro effects of fluor-hydroxyapatite, fluorapatite and hydroxyapatite on colony formation, DNA damage and mutagenicity.

    PubMed

    Jantová, S; Theiszová, M; Letasiová, S; Birosová, L; Palou, T M

    2008-04-30

    The number of biomaterials used in biomedical applications has rapidly increased in the past two decades. Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard-tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetically prepared composite that in its structure contains the same molecular concentration of OH(-) groups and F(-) ions. The aim of this experimental investigation was to evaluate cytotoxic, genotoxic and mutagenic effects of FHA and FA eluates on Chinese hamster V79 cells and to compare them with the effects of hydroxyapatite (HA) eluate. Cytotoxicity of the biomaterials tested was evaluated by use of the cell colony-formation assay and by direct counting of the cells in each colony. Genotoxicity was assessed by single-cell gel electrophoresis (comet assay) and mutagenicity was evaluated by the Hprt gene-mutation assay and in bacterial mutagenicity tests using Salmonella typhimurium TA100. The results show that the highest test concentrations of the biomaterials (100% and 75% eluates) induced very weak inhibition of colony growth (about 10%). On the other hand, the reduction of cell number per colony induced by these concentrations was in the range from 43% to 31%. The comet assay showed that biomaterials induced DNA breaks, which increased with increasing test concentrations in the order HA

  8. On the anisotropic elastic properties of hydroxyapatite.

    NASA Technical Reports Server (NTRS)

    Katz, J. L.; Ukraincik, K.

    1971-01-01

    Experimental measurements of the isotropic elastic moduli on polycrystalline specimens of hydroxyapatite and fluorapatite are compared with elastic constants measured directly from single crystals of fluorapatite in order to derive a set of pseudo single crystal elastic constants for hydroxyapatite. The stiffness coefficients thus derived are given. The anisotropic and isotropic elastic properties are then computed and compared with similar properties derived from experimental observations of the anisotropic behavior of bone.

  9. Hydrophobicity, surface tension, and zeta potential measurements of glass-reinforced hydroxyapatite composites.

    PubMed

    Lopes, M A; Monteiro, F J; Santos, J D; Serro, A P; Saramago, B

    1999-06-15

    Wettability and zeta potential studies were performed to characterize the hydrophobicity, surface tension, and surface charge of P2O5-glass-reinforced hydroxyapatite composites. Quantitative phase analysis was performed by the Rietveld method using GSAS software applied to X-ray diffractograms. Surface charge was assessed by zeta potential measurements. Protein adsorption studies were performed using vitronectin. Contact angles and surface tensions variation with time were determined by the sessile and pendent drop techniques, respectively, using ADSA-P software. The highest (-18.1 mV) and lowest (-28.7 mV) values of zeta potential were found for hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), respectively, with composite materials presenting values in between. All studied bioceramic materials showed similar solid surface tension. For HA and beta-TCP, solid surface tensions of 46.7 and 45.3 mJ/m2, respectively, were obtained, while composites presented intermediate surface tension values. The dispersive component of surface tension was the predominant one for all materials studied. Adhesion work values between the vitronectin solution and HA and beta-TCP were found to be 79.8 and 88.0 mJ/m2, respectively, while the 4.0 wt % glass composites showed slightly lower values than the 2.5 wt % ones. The presence of beta-TCP influenced surface charge, hydrophobicity, and protein adsorption of the glass-reinforced HA composites, and therefore indirectly affected cell-biomaterial interactions.

  10. Sol-gel derived fluor-hydroxyapatite biocoatings on zirconia substrate.

    PubMed

    Kim, Hae-Won; Kong, Young-Min; Bae, Chang-Jun; Noh, Yoon-Jung; Kim, Hyoun-Ee

    2004-07-01

    Fluor-hydroxyapatite (FHA) film was coated on a zirconia (ZrO(2)) substrate by a sol-gel method. An appropriate amount of F ions was incorporated into the hydroxyapatite (HA) during the preparation of the sols. The apatite phase began to crystallize after heat treatment at 400 degrees C, and increased in intensity above 500 degrees C. No decomposition was detected by X-ray diffraction analyses up to 800 degrees C, which illustrates the high thermal stability of the FHA films. The films showed a uniform and dense morphology with a thickness of approximately 1 microm after a precisely controlled heat treatment process. These FHA films adhered firmly to the zirconia substrate, representing notable adhesion strengths of approximately 70 MPa after heat treatment above 500 degrees C. The dissolution rate of the FHA coating layer varied according to the heat treatment temperature, which was closely related to the film crystallinity. The dissolution rate of the FHA film was lower than that of the HA film, suggesting the possibility of a functional gradient coating of HA and FHA. The MG63 cells seeded onto the FHA films proliferated in a similar manner to those seeded onto pure HA ceramic and a plastic control.

  11. Effect of aging temperature on formation of sol-gel derived fluor-hydroxyapatite nanoparticles.

    PubMed

    Joughehdoust, S; Behnamghader, A; Jahandideh, R; Manafi, S

    2010-04-01

    Synthetic hydroxyapatite (HA) has been recognized as one of the most important bone substitute materials in orthopaedics and dentistry over past few decades because of its chemical and biological similarity to the mineral phase of human bone. One solution for reduction the solubility of HA in biological environments is replacing F- by OH in HA structure and forming fluor-hydroxyapatite (FHA) solid solution. In this paper, FHA nanoparticles were successfully synthesized by a sol-gel method. Also, the influence of aging temperature on formation of FHA powder was studied. Equimolar solutions of calcium nitrate tetrahydrate, triethyl phosphite and ammonium fluoride in ethanol were used as Ca, P and F precursors. After aging at different temperatures, the synthesized powders were heat treated at 550 degrees C. The powders were investigated with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), energy dispersive analysis of X-ray (EDAX) and zetasizer measurement. The results of XRD proved the presence of fluorapatite (FA) and HA in all samples. In addition, the formation of FHA was confirmed by FT-IR results. XRD studies also showed that the crystallites were in nanometric scale. At the same time, this result was in good agreement with the result of zetasizer analysis.

  12. A novel thermo-sensitive hydrogel based on thiolated chitosan/hydroxyapatite/beta-glycerophosphate.

    PubMed

    Liu, Xujie; Chen, Yan; Huang, Qianli; He, Wei; Feng, Qingling; Yu, Bo

    2014-09-22

    In order to get a water-soluble in situ gel-forming system, a thiolated chitosan, chitosan-4-thio-butylamidine (CS-TBA) conjugate was synthesized and used to replace the unmodified chitosan in the application of the in situ gel-forming system. A novel thermo-sensitive hydrogel was prepared based on CS-TBA/hydroxyapatite (HA)/beta-glycerophosphate disodium (β-GP). The gel formation, rheological properties, morphology, degradation, cytotoxicity, as well as protein release process of the novel gel system were investigated in this study. The CS-TBA/HA/β-GP gel showed a higher storage modulus (G') and loss modulus (G″) and a decreased bovine serum albumin (BSA) release rate which was maintained the protein release for a longer time compared with the unmodified chitosan (CS)/HA/β-GP gel, due to the existence of thiol groups and/or disulfide bonds. The CS-TBA/HA/β-GP gel has a porous structure with a uniform distribution of nano-hydroxyapatite, an appropriate degradation rate and low cytotoxicity, showing potential applications in drug delivery and tissue engineering.

  13. Substituted hydroxyapatites for bone repair.

    PubMed

    Shepherd, Jennifer H; Shepherd, David V; Best, Serena M

    2012-10-01

    Calcium phosphates such as hydroxyapatite have a wide range of applications both in bone grafts and for the coating of metallic implants, largely as a result of their chemical similarity to the mineral component of bone. However, to more accurately mirror the chemistry, various substitutions, both cationic (substituting for the calcium) and anionic (substituting for the phosphate or hydroxyl groups) have been produced. Significant research has been carried out in the field of substituted apatites and this paper aims to summarise some of the key effect of substitutions including magnesium, zinc, strontium, silicon and carbonate on physical and biological characteristics. Even small substitutions have been shown to have very significant effects on thermal stability, solubility, osteoclastic and osteoblastic response in vitro and degradation and bone regeneration in vivo.

  14. Osteopontin, osteocalcin and OB-cadherin expression in Synthetic nanohydroxyapatite vs bovine hydroxyapatite cultured Osteoblastic-like cells.

    PubMed

    Santarelli, A; Mascitti, M; Orsini, G; Memè, L; Rocchetti, R; Tiriduzzi, P; Sampalmieri, F; Putignano, A; Procaccini, M; Lo Muzio, L; Bambini, F

    2014-01-01

    Calcium phosphate ceramics have been applied in bone replacement for several decades due to their excellent biocompatibility, bioactivity, osteo-conductivity and mechanical strength. Several studies have demonstrated that porous hydroxyapatite (HA) is an excellent scaffold for osteogenic proliferation and differentiation of the osteoprogenitor cells. However, different methods of synthesis and production of HA ceramic-based materials may have considerable effect on the physical and biological properties. In the present work, two hydroxyapatite-based materials, a natural hydroxyapatite ceramic of bovine origin and a synthetic nano-cristalline hydroxyapatite were tested in vitro with MG63 cell line. The results displayed that both the materials demonstrated a good biocompatibility. The immunocytochemical stain revealed a different positivity of the osteogenic markers between the cultures with the biomaterials, and the control culture. Western blot data confirmed the immunocytochemical stain. Both the materials tested in the present study demonstrated a good biocompatibility with the osteoblastic cells allowing, at the same time, the osteogenic differentiation, and they may be useful in clinical use.

  15. Hydroxyapatite porous scaffold engineered with biological polymer hybrid coating for antibiotic Vancomycin release.

    PubMed

    Kim, Hae-Won; Knowles, Jonathan C; Kim, Hyoun-Ee

    2005-03-01

    The purpose of this study is to improve hydroxyapatite (HA) porous scaffolds via coating with biological polymer-HA hybrids for use as wound healing and tissue regeneration. Highly porous HA scaffolds, fabricated by a polyurethane foam reticulate method, were coated with hybrid coating solution, consisting of poly(epsilon-caprolactone) (PCL), HA powders, and the antibiotic Vancomycin. The PCL to HA ratio was fixed at 1.5 and the drug amounts were varied [drug/(PCL + HA) = 0.02 and 0.04]. For the purpose of comparison, bare HA scaffold without the hybrid coating layer was also loaded with Vancomycin via an immersion-adsorption method. The hybrid coating structure and morphology were observed with Fourier transformed infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The effects of the hybrid coating on the compressive mechanical properties and the in vitro drug release of the scaffolds were investigated in comparison with bare HA scaffold. The PCL-HA hybrid coating altered the scaffold pore structure slightly, resulting in thicker stems and reduced porosity. With the hybrid coating, the HA scaffold responded to an applied compressive stress more effectively without showing a brittle failure. This was attributed to the shielding and covering of the framework surface by the coating layer. The encapsulated drugs within the coated scaffold was released in a highly sustained manner as compared to the rapid release of drugs directly adsorbed on the pure HA scaffold. These findings suggest that the coated HA scaffolds expand their applicability in hard tissue regeneration and wound healing substitutes delivering bioactive molecules.

  16. Synthesis, Characterization, and Biological Evaluation of Nanostructured Hydroxyapatite with Different Dimensions

    PubMed Central

    Geng, Zhen; Yuan, Qin; Zhuo, Xianglong; Li, Zhaoyang; Cui, Zhenduo; Zhu, Shengli; Liang, Yanqin; Liu, Yunde; Bao, Huijing; Li, Xue; Huo, Qianyu; Yang, Xianjin

    2017-01-01

    Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should be considered. In this study, nanosized HA and SrHA with different dimensions and crystallization were synthesized by hydrothermal methods. The phase, crystallization and chemical composition were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The morphology was observed under field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The degradation behaviors of the samples were monitored by determining the ions release profile with inductively coupled plasma mass spectrometry (ICP-MS). The releasing behavior of Ca2+ and Sr2+ showed that the degradation rate was proportional to the specific surface area and inversely proportional to crystallization. The in vitro experiment evaluated by MG63 cells showed that SrHA nanorods with a length greater than 100 nm had the best biological performance both in cell proliferation and differentiation (* p < 0.05 compared with HA-1 and SrHA-1; * p < 0.01 compared with HA-2). In addition, HA nanoparticles with a lower aspect ratio had better bioactivity than higher ones (* p < 0.05). This study demonstrated that nanosized HA and SrHA with subtle differences (including dimensions, crystallization, specific surface area, and degradation rate) could affect the cellular growth and thus might have an impact on bone growth in vivo. This work provides a view of the role of nano-HAs as ideal biocompatible materials in future clinical applications. PMID:28336873

  17. Hydrogel microspheres for stabilization of an antioxidant enzyme: effect of emulsion cross-linking of a dual polysaccharide system on the protection of enzyme activity.

    PubMed

    Tang, Deh-Wei; Yu, Shu-Huei; Wu, Wen-Shin; Hsieh, Hao-Ying; Tsai, Yi-Chin; Mi, Fwu-Long

    2014-01-01

    Catalase is an antioxidant enzyme abundant in natural resources. However, the enzyme is usually inactivated by gastric acid and digestive enzymes after oral ingestion. In this study, carboxymethyl chitosan (CM-chitosan) and hyaluronic acid (HA) conjugate hydrogel microspheres have been prepared by an emulsion cross-linking technique to retain the activity of catalase in simulated gastrointestinal (GI) fluids. Cross-linking reduced the swelling capability and increased the resistance toward hyaluronidase digestion of prepared HA-CM-chitosan hydrogel microspheres. Catalase entrapped in the hydrogel microspheres exhibited superior stability over a wide pH range (pH 2.0 and 6.0-8.0) as compared to the native enzyme. The entrapped catalase was also protected against degradation by digestive enzymes. Following the treatments, the catalase-loaded microspheres, in contrast to native catalase, could effectively decrease the intracellular H2O2 level and protect HT-29 colonic epithelial cells against H2O2-induced oxidative damage to preserve cell viability. These results suggested that the HA-CM-chitosan hydrogel microspheres can be used for entrapment, protection and intestinal delivery of catalase for H2O2 scavenging.

  18. Design, fabrication, and characterization of laminated hydroxyapatite-polysulfone composites

    NASA Astrophysics Data System (ADS)

    Wilson, Clifford Adams, II

    There exists a need to develop devices that can be used to replace hard tissues, such as bone, in load-bearing areas of the body. An ideal hard tissue replacement device is one that stimulates growth of natural tissues, and is slowly resorbed by the body. The implant is also required to have elastic modulus, strength, and toughness values similar to the tissues being replaced. Hydroxyapatite (HA) is the primary mineral phase of bone and has the potential for use in biomedical applications because it stimulates cell growth and is resorbable. Unfortunately, HA is a relatively low strength, low toughness material, which limits its application to only low load-bearing regions of the body. In order to apply HA to greater load-bearing areas of the body, strength and toughness must be improved through the formation of a composite structure. The goal of this study to show that a composite structure formed from HA and a biocompatible polymer can be fabricated with strength and toughness values that are within the range necessary for load-bearing biomedical applications. Therefore, Polysulfone-HA composites were developed and tested. Polysulfone (PSu) is a hard, glassy polymer that has been shown to be biocompatible. Composites were fabricated through a combination of tape casting, solvent casting, and lamination. Monolithic HA and laminate specimens were tested in biaxial flexure. A unique laminate theory solution was developed to characterize stress distributions for laminates. Failure loads, failure stress, work of fracture, and apparent toughness were compared for the laminates against monolithic HA specimens. Initial testing results showed that laminates had a failure stress of 60 +/- 10, which is a 170% improvement over the 22 +/- 2 MPa failure stress for monolithic HA. The work of fracture was improved by 5500% from 11 +/- 2 for the monolithic HA to 612 +/- 240 for the laminates. Work of fracture values gave the laminates an apparent fracture toughness of 7.2 MPa•m1

  19. The Tissue Implant Response Surrounding Subcutaneous TCP, HA, And ALCAP Bioceramics.

    PubMed

    Butler, K R; Benghuzzi, Hamed; Tucci, Michelle; Puckett, A D

    2015-01-01

    The objective of this investigation was to quantify and further elucidate the tissue-implant response in the fibrous tissue surrounding tricalcium phosphate (TCP), hydroxyapatite (HA), and aluminum calcium phosphate (ALCAP) implants when implanted subcutaneously. Sixteen animals in four experimental groups (n = 4/group) were implanted with one implant each: Group I (control, TCP), Group II (HA), and Group III (ALCAP). At 90 days post-implantation, the fibrous tissue surrounding the implants was harvested. Sections of stained fibrous tissue were evaluated for the presence of macrophages, fibrocytes, neutrophils, vascularity and thickness for all three groups using semi-automated quantitative methods. The analysis indicated Group III demonstrated a significantly higher number of neutrophils but fewer macrophages and blood vessels per high power field and had a substantially thinner fibrous tissue capsule thickness compared to Groups I and II (alpha=0.05). Group II elicited a greater response of fibroblasts compared to Groups I and III suggesting HA may provide a slightly higher degree of stability to the implant. In total, these findings suggest both TCP and HA behave similarly in vivo when compared to ALCAP and may be better choices for subcutaneous soft-tissue application compared to ALCAP.

  20. Biphasic calcium phosphates: influence of three synthesis parameters on the HA/beta-TCP ratio.

    PubMed

    Bouler, J M; LeGeros, R Z; Daculsi, G

    2000-09-15

    Hydroxyapatite (HA) contents measurements were conducted on eight biphasic calcium phosphate (BCP) samples obtained by sintering calcium-deficient apatite formed previously by hydrolyzing a dicalcium phosphate dihydrate (DCPD) powder. We evaluated the influences and interactions of three synthesis factors: alkalinity, process duration, and concentration of the water suspension in DCPD. Those parameters were varied simultaneously between two limit levels. Experiments used a factorial design method (FDM) allowing optimization of the number of samples as well as statistical analysis of results. FDM showed that HA content, in a defined experimental area, can be described by a first-order polynomial equation in which the initial alcalinity and the DCPD/water ratio are the major influences. Experiment prove that pH measured at the end of the hydrolysis was predictive of the HA content in the final BCP. This study leads up to an isoresponse line diagram which will allow the synthesis of some BCP with fitted HA/beta-tricalcium phosphate ratios.

  1. Laminated electrospun nHA/PHB-composite scaffolds mimicking bone extracellular matrix for bone tissue engineering.

    PubMed

    Chen, Zhuoyue; Song, Yue; Zhang, Jing; Liu, Wei; Cui, Jihong; Li, Hongmin; Chen, Fulin

    2017-03-01

    Electrospinning is an effective means to generate nano- to micro-scale polymer fibers resembling native extracellular matrix for tissue engineering. However, a major problem of electrospun materials is that limited pore size and porosity may prevent adequate cellular infiltration and tissue ingrowth. In this study, we first prepared thin layers of hydroxyapatite nanoparticle (nHA)/poly-hydroxybutyrate (PHB) via electrospinning. We then laminated the nHA/PHB thin layers to obtain a scaffold for cell seeding and bone tissue engineering. The results demonstrated that the laminated scaffold possessed optimized cell-loading capacity. Bone marrow mesenchymal stem cells (MSCs) exhibited better adherence, proliferation and osteogenic phenotypes on nHA/PHB scaffolds than on PHB scaffolds. Thereafter, we seeded MSCs onto nHA/PHB scaffolds to fabricate bone grafts. Histological observation showed osteoid tissue formation throughout the scaffold, with most of the scaffold absorbed in the specimens 2months after implantation, and blood vessels ingrowth into the graft could be observed in the graft. We concluded that electrospun and laminated nanoscaled biocomposite scaffolds hold great therapeutic potential for bone regeneration.

  2. BMP-2 Grafted nHA/PLGA Hybrid Nanofiber Scaffold Stimulates Osteoblastic Cells Growth

    PubMed Central

    Haider, Adnan; Kim, Sukyoung; Huh, Man-Woo; Kang, Inn-Kyu

    2015-01-01

    Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/degenerated tissues or organs. Natural bone is a hierarchical structure, comprised of various cells having specific functions that are regulated by sophisticated mechanisms. However, the regulation of the normal functions in damaged or injured cells is disrupted. In order to address this problem, we attempted to artificially generate a scaffold for mimicking the characteristics of the extracellular matrix at the nanoscale level to trigger osteoblastic cell growth. For this purpose, we have chemically grafted bone morphogenetic protein (BMP-2) onto the surface of L-glutamic acid modified hydroxyapatite incorporated into the PLGA nanofiber matrix. After extensive characterization using various spectroscopic techniques, the BMP-g-nHA/PLGA hybrid nanofiber scaffolds were subjected to various in vitro cytocompatibility tests. The results indicated that BMP-2 on BMP-g-nHA/PLGA hybrid nanofiber scaffolds greatly stimulated osteoblastic cells growth, contrary to the nHA/PLGA and pristine PLGA nanofiber scaffold, which are used as control. These results suggest that BMP-g-nHA/PLGA hybrid nanofiber scaffold can be used as a nanodrug carrier for the controlled and targeted delivery of BMP-2, which will open new possibilities for enhancing bone tissue regeneration and will help in the treatment of various bone-related diseases in the future. PMID:26539477

  3. Nanocrystalline structure of the surface layer of plasma-sprayed hydroxyapatite coatings obtained upon preliminary induction heat treatment of metal base

    NASA Astrophysics Data System (ADS)

    Fomin, A. A.; Steinhauer, A. B.; Lyasnikov, V. N.; Wenig, S. B.; Zakharevich, A. M.

    2012-05-01

    Biocompatible nanocrystalline hydroxyapatite (HA) coatings for intrabone titanium implants have been obtained by plasma spraying. The HA coatings have an average grain size within 10-30 nm and are characterized by improved characteristics of morphological heterogeneity that is acquired due to the induction heat treatment (IHT) of substrates prior to plasma spray deposition. Based on the data of scanning electron microscopy with computer-aided processing of images, it is established that the average grain size depends on the IHT temperature.

  4. Investigation of the HA film deposited on the porous Ti6Al4V alloy prepared via additive manufacturing

    NASA Astrophysics Data System (ADS)

    Surmeneva, M.; Chudinova, E.; Syrtanov, M.; Koptioug, A.; Surmenev, R.

    2015-11-01

    This study is focused on the use of radio frequency magnetron sputtering to modify the surface of porous Ti6Al4V alloy fabricated via additive manufacturing technology. The hydroxyapatite (HA) coated porous Ti6Al4V alloy was studied in respect with its chemical and phase composition, surface morphology, water contact angle and hysteresis, and surface free energy. Thin nanocrystalline HA film was deposited while its structure with diamond-shaped cells remained unchanged. Hysteresis and water contact angle measurements revealed an effect of the deposited HA films, namely an increased water contact angle and contact angle hysteresis. The increase of the contact angle of the coating-substrate system compared to the uncoated substrate was attributed to the multiscale structure of the resulted surfaces.

  5. Effect of Hydroxyapatite porous characteristics on healing outcomes in rabbit posterolateral spinal fusion model.

    PubMed

    Motomiya, Makoto; Ito, Manabu; Takahata, Masahiko; Kadoya, Ken; Irie, Kazuharu; Abumi, Kuniyoshi; Minami, Akio

    2007-12-01

    Hydroxyapatite (HA) has been commonly used as a bone graft substitute in various kinds of clinical fields. To improve the healing capability of HA, many studies have been performed to reveal its optimal structural characteristics for better healing outcomes. In spinal reconstruction surgery, non-interconnected porous HAs have already been applied as a bone graft extender in order to avoid autogenous bone harvesting. However, there have been few experimental studies regarding the effects of the structural characteristics of HA in posterolateral lumbar intertransverse process spine fusion (PLF). The aims of this study were to investigate the effect of HA porous characteristics on healing outcomes in a rabbit PLF model in order to elucidate appropriate structural characteristics of HA as a bone graft extender. Thirty-six adult female Japanese White rabbits underwent bilateral intertransverse process fusion at the level of L5-6 without internal fixation. We prepared three types of HA with different porosities: HA with 15% porosity (HA15%), HA with 50% porosity (HA50%), and HA with 85% porosity (HA85%), all of which were clinically available materials. The HA15% and HA50% had few interconnecting pores, whereas the HA85%, which was a recently developed material, had abundant interconnecting pores. All rabbits were randomly divided into the following four groups according to the grafted materials: (1) HA15% + autogenous bone, (2) HA50% + autogenous bone, (3) HA85% + autogenous bone, (4) pure autogenous bone graft. The animals were euthanized at 5 weeks after surgery, and post-mortem analyses including biomechanical testing, radiographical and histological evaluations were performed. There was no statistically significant difference in either fusion rate and/or bending stiffness among the three HA groups. However, in histological and radiological analyses, both bone ingrowth rate and direct bone bonding rate in the HA85% group were significantly higher than those in the HA

  6. Preparation and characterization of novel biphasic calcium phosphate powders (alpha-TCP/HA) derived from carbonated amorphous calcium phosphates.

    PubMed

    Li, Yanbao; Kong, Fanzhi; Weng, Wenjian

    2009-05-01

    Novel biphasic calcium phosphate (BCP) powders composed of alpha-tricalcium phosphate (alpha-TCP) and hydroxyapatite (HA) were prepared by thermal decomposition of carbonated amorphous calcium phosphates (CACP). At first, the CACP precipitates were synthesized by adding ammonium carbonate in the presence of poly(ethylene glycol) at pH 10 with an initial Ca/P molar ratio of 1.60 at 5 degrees C. The Ca/P molar ratios of the CACP precursors are between 1.50 and 1.67 investigated by ICP. Then BCP (alpha-TCP/HA) powders were obtained after heating the CACP precursors at relatively low temperature (800 degrees C) for 3 h. alpha-TCP/HA powders were characterized by X-ray diffractometry, Fourier transform infrared spectra, transmission electron microscopy/scanning electron microscopy, and sedimentation experiment. The results show that alpha-TCP and HA phases form in one powder, alpha-TCP/HA powders are sphere with the diameter of 300 nm to less than 100 nm varied with their chemical compositions and the ratio of alpha-TCP and HA in the powders can be adjusted by the adding amount of carbonates. The possible formation process of biphasic alpha-TCP/HA powders was proposed.

  7. Fabrication and in vitro biocompatibility of biomorphic PLGA/nHA composite scaffolds for bone tissue engineering.

    PubMed

    Qian, Junmin; Xu, Weijun; Yong, Xueqing; Jin, Xinxia; Zhang, Wei

    2014-03-01

    In this study, biomorphic poly(dl-lactic-co-glycolic acid)/nano-hydroxyapatite (PLGA/nHA) composite scaffolds were successfully prepared using cane as a template. The porous morphology, phase, compression characteristics and in vitro biocompatibility of the PLGA/nHA composite scaffolds and biomorphic PLGA scaffolds as control were investigated. The results showed that the biomorphic scaffolds preserved the original honeycomb-like architecture of cane and exhibited a bimodal porous structure. The average channel diameter and micropore size of the PLGA/nHA composite scaffolds were 164 ± 52 μm and 13 ± 8 μm, respectively, with a porosity of 89.3 ± 1.4%. The incorporation of nHA into PLGA decreased the degree of crystallinity of PLGA, and significantly improved the compressive modulus of biomorphic scaffolds. The in vitro biocompatibility evaluation with MC3T3-E1 cells demonstrated that the biomorphic PLGA/nHA composite scaffolds could better support cell attachment, proliferation and differentiation than the biomorphic PLGA scaffolds. The localization depth of MC3T3-E1 cells within the channels of the biomorphic PLGA/nHA composite scaffolds could reach approximately 400 μm. The results suggested that the biomorphic PLGA/nHA composite scaffolds were promising candidates for bone tissue engineering.

  8. Nuclear fuel microsphere gamma analyzer

    DOEpatents

    Valentine, Kenneth H.; Long, Jr., Ernest L.; Willey, Melvin G.

    1977-01-01

    A gamma analyzer system is provided for the analysis of nuclear fuel microspheres and other radioactive particles. The system consists of an analysis turntable with means for loading, in sequence, a plurality of stations within the turntable; a gamma ray detector for determining the spectrum of a sample in one section; means for analyzing the spectrum; and a receiver turntable to collect the analyzed material in stations according to the spectrum analysis. Accordingly, particles may be sorted according to their quality; e.g., fuel particles with fractured coatings may be separated from those that are not fractured, or according to other properties.

  9. Solid evacuated microspheres of hydrogen

    DOEpatents

    Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

    1982-01-01

    A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

  10. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  11. Morphology and crystallinity of the nanosized hydroxyapatite synthesized by hydrolysis using cetyltrimethylammonium bromide (CTAB) as a surfactant

    NASA Astrophysics Data System (ADS)

    Shih, Wei-Jen; Wang, Moo-Chin; Hon, Min-Hsiung

    2005-02-01

    The biodegradable hydroxyapatite (HA) was synthesized by hydrolysis and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). The HA synthesized from CaHPO 4·2H 2O(DCPD) in 2.5 M NaOH (aq) at 75 °C for 1 h had a size of 50 nm in width and 100 nm in length. However, the HA aggregates synthesized from DCPD in 2.5 M NaOH (aq) with cetyltrimethylammonium bromide (CTAB) as a surfactant were elongated. When the CTAB concentration was increased from 1×10 -4 to 1×10 -2 M, the synthesized HA became thinner to a size of 5-20 nm in width and 50 nm in length. For thinner HA aggregates, longer agglomerates were aligned in the synthesis without the CTAB surfactant.

  12. Mechanical and biological properties of the micro-/nano-grain functionally graded hydroxyapatite bioceramics for bone tissue engineering.

    PubMed

    Zhou, Changchun; Deng, Congying; Chen, Xuening; Zhao, Xiufen; Chen, Ying; Fan, Yujiang; Zhang, Xingdong

    2015-08-01

    Functionally graded materials (FGM) open the promising approach for bone tissue repair. In this study, a novel functionally graded hydroxyapatite (HA) bioceramic with micrograin and nanograin structure was fabricated. Its mechanical properties were tailored by composition of micrograin and nanograin. The dynamic mechanical analysis (DMA) indicated that the graded HA ceramics had similar mechanical property compared to natural bones. Their cytocompatibility was evaluated via fluorescent microscopy and MTT colorimetric assay. The viability and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs) on ceramics indicated that this functionally graded HA ceramic had better cytocompatibility than conventional HA ceramic. This study demonstrated that functionally graded HA ceramics create suitable structures to satisfy both the mechanical and biological requirements of bone tissues.

  13. Synthesis and Characterization of Hydroxyapatite/Fullerenol Nanocomposites.

    PubMed

    Djordjevic, Aleksandar; Ignjatovic, Nenad; Seke, Mariana; Jovic, Danica; Uskokovic, Dragan; Rakocevic, Zlatko

    2015-02-01

    Fullerenols are polyhydroxylated, water soluble derivatives of fullerene C60, with potential application in medicine as diagnostic agents, antioxidants or nano drug carriers. This paper describes synthesis and physical characterization of a new nanocomposite hydroxyapatite/fullerenol. Surface of the nanocomposite hydroxyapatite/fullerenol is inhomogeneous with the diameter of the particles in the range from 100 nm to 350 nm. The ζ potential of this nanocomposite is ten times lower when compared to hydroxyapatite. Surface phosphate groups of hydroxyapatite are prone to forming hydrogen bonds, when in close contact with hydroxyl groups, which could lead to formation of hydrogen bonds between hydroxyapatite and hydroxyl groups of fullerenol. The surface of hydroxyapatite particles (-2.5 mV) was modified by fullerenol particles, as confirmed by the obtained ζ potential value of the nanocomposite biomaterial hydroxyapatite/fullerenol (-25.0 mV). Keywords: Hydroxyapatite, Fullerenol, Nanocomposite, Surface Analysis.

  14. Influenza Hemagglutinin (HA) Stem Region Mutations That Stabilize or Destabilize the Structure of Multiple HA Subtypes

    PubMed Central

    Byrd-Leotis, Lauren; Galloway, Summer E.; Agbogu, Evangeline

    2015-01-01

    ABSTRACT Influenza A viruses enter host cells through endosomes, where acidification induces irreversible conformational changes of the viral hemagglutinin (HA) that drive the membrane fusion process. The prefusion conformation of the HA is metastable, and the pH of fusion can vary significantly among HA strains and subtypes. Furthermore, an accumulating body of evidence implicates HA stability properties as partial determinants of influenza host range, transmission phenotype, and pathogenic potential. Although previous studies have identified HA mutations that can affect HA stability, these have been limited to a small selection of HA strains and subtypes. Here we report a mutational analysis of HA stability utilizing a panel of expressed HAs representing a broad range of HA subtypes and strains, including avian representatives across the phylogenetic spectrum and several human strains. We focused on two highly conserved residues in the HA stem region: HA2 position 58, located at the membrane distal tip of the short helix of the hairpin loop structure, and HA2 position 112, located in the long helix in proximity to the fusion peptide. We demonstrate that a K58I mutation confers an acid-stable phenotype for nearly all HAs examined, whereas a D112G mutation consistently leads to elevated fusion pH. The results enhance our understanding of HA stability across multiple subtypes and provide an additional tool for risk assessment for circulating strains that may have other hallmarks of human adaptation. Furthermore, the K58I mutants, in particular, may be of interest for potential use in the development of vaccines with improved stability profiles. IMPORTANCE The influenza A hemagglutinin glycoprotein (HA) mediates the receptor binding and membrane fusion functions that are essential for virus entry into host cells. While receptor binding has long been recognized for its role in host species specificity and transmission, membrane fusion and associated properties of HA

  15. Preparation and Properties of Bamboo Fiber/Nano-hydroxyapatite/Poly(lactic-co-glycolic) Composite Scaffold for Bone Tissue Engineering.

    PubMed

    Jiang, Liuyun; Li, Ye; Xiong, Chengdong; Su, Shengpei; Ding, Haojie

    2017-02-08

    In this study, bamboo fiber was first designed to incorporate into nano-hydroxyapatite/poly(lactic-co-glycolic) to obtain a new composite scaffold of bamboo fiber/nano-hydroxyapatite/poly(lactic-co- glycolic) (BF/n-HA/PLGA) by freeze-drying method. The effect of their components and some factors consisting of different freeze temperatures, concentrations, and pore-forming agents on the porous morphology, porosity, and compressive properties of the scaffold were investigated by scanning electron microscope, modified liquid displacement method, and electromechanical universal testing machine. The results indicated that the 5% BF/30% n-HA/PLGA composite scaffold, prepared with 5% (w/v) high concentration and frozen at -20 °C without pore-forming agent, had the best ideal porous structure and porosity as well as compressive properties, which far exceed those of n-HA/PLGA composite scaffold. In addition, the in vitro simulated body fluids soaking and cell culture experiment showed the addition of BF into the scaffold accelerated the BF/n-HA/PLGA composite scaffolds degradation and exhibited good cytocompatibility, including attachment and proliferation. All the results of the study show that BF has improved the properties of n-HA/PLGA composite scaffolds and BF/n-HA/PLGA might have a great potential for bone tissue engineering scaffold.

  16. Synthesis and structural characterization of nano-hydroxyapatite biomaterials prepared by microwave processing

    NASA Astrophysics Data System (ADS)

    Ramli, Rosmamuhamadani; Arawi, Ainaa Zafirah Omar; Talari, Mahesh Kumar; Mahat, Mohd Muzamir; Jais, Umi Sarah

    2012-07-01

    Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. Synthetic HA exhibits excellent osteoconductive properties. Osteoconductivity means the ability to provide the appropriate scaffold or template for bone formation. Calcium phosphate biomaterials [(HA), tri-calcium phosphate (TCP) and biphasic calcium phosphate (HA/TCP)] with appropriate three-dimensional geometry are able to bind and concentrate endogenous bone morphogenetic proteins in circulation, and may become osteoinductive and can be effective carriers of bone cell seeds. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, HA-nanoparticles of different crystallite size were prepared by microwave synthesis of precursors. High purity CaO was extracted from the natural mussel shells for the synthesis of nano HA. Dried nano HA powders were analyzed using X-Ray Diffraction (XRD) technique for the determination of crystal structure and impurity content. Scanning Electron Microscopic (SEM) investigation was employed for the morphological investigation of nano HA powders. From the results obtained, it was concluded that by altering the irradiation time, nano HA powders of different crystallite sizes and morphologies could be produced. Crystallite sizes calculated from the XRD patterns are found to be in the range of 10-55 nm depending on the irradiation time.

  17. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.

  18. Randomized controlled clinical trial of 2 types of hydroxyapatite-coated implants on moderate periodontitis patients

    PubMed Central

    2016-01-01

    Purpose The aim of this study was to compare and analyze the peri-implant tissue conditions and prospective clinical outcomes associated with 2 types of hydroxyapatite (HA)-coated implants: (1) fully HA-coated implants and (2) partially HA-coated implants with resorbable blast medium on the coronal portion of the threads. Methods Forty-four partially edentulous patients were randomly assigned to undergo the placement of 62 HA-coated implants, and were classified as the control group (partially HA-coated, n=30) and the test group (fully HA-coated, n=32). All patients had chronic periodontitis with moderate crestal bone loss around the edentulous area. The stability and clinical outcomes of the implants were evaluated using the primary and secondary implant stability quotient (ISQ), as well as radiographic, mobility, and peri-implant soft tissue assessments around the implants. The Wilcoxon signed-rank test and the Mann-Whitney test were used to evaluate differences between and within the 2 groups, with P values <0.05 considered to indicate statistical significance. Results The fully HA-coated implants displayed good retention of crestal bone, and insignificant differences were found in annual marginal bone loss between the 2 types of HA-coated implants (P>0.05). No significant differences were found in the survival rate (group I, 100%; group II, 100%) or the success rate (group I, 93.3%; group II, 93.8%). The fully HA-coated implants also did not significantly increase the risk of peri-implantitis (P>0.05). Conclusions The fully HA-coated implants did not lead to an increased risk of peri-implantitis and showed good retention of the crestal bone, as well as good survival and success rates. Our study suggests that fully HA-coated implants could become a reliable treatment alternative for edentulous posterior sites and are capable of providing good retention of the crestal bone. PMID:27800216

  19. Production of biologically safe and mechanically improved reduced graphene oxide/hydroxyapatite composites

    NASA Astrophysics Data System (ADS)

    Elif, Öztürk; Belma, Özbek; İlkay, Şenel

    2017-01-01

    As research trends included the improvement of the mechanical properties of hydroxyapatite (HA) for biological applications, HA was reinforced with different concentrations of reduced graphene oxide (RGO) in HA. In this context, graphene oxide was synthesized using the chemical exfoliation method and reduced using an environmentally safe and green method. As a green method, RGO was obtained using Melissa officinalis (melisa) extract and used as a second phase combination to the HA structure. RGO-HA composites with different concentrations of RGO in HA (0.25, 0.5, 1.0, 2.0% wt.) were prepared using the liquid precipitation method. Then they were pelleted and sintered. Characterization studies were carried out using UV-vis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), zetasizer (ZS), x-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The mechanical properties of the composites were analyzed using a universal testing machine. Compared to pure HA, the compressive strength values of composites were increased significantly with the increase in RGO content. The optimum increase was observed for the RGO-HA (1%) composite, which was 3.2 times higher than the pure HA sample. Therefore, the RGO-HA (1%) composite was chosen as the best composition, and its cytotoxic and proliferative effects were examined using a minimum essential media elution test and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The results showed that RGO-HA (1%) composites are biocompatible and even though they are proliferative at concentrations lower than 25%.

  20. Electrophoretic deposition of graphene oxide reinforced chitosan-hydroxyapatite nanocomposite coatings on Ti substrate.

    PubMed

    Shi, Y Y; Li, M; Liu, Q; Jia, Z J; Xu, X C; Cheng, Y; Zheng, Y F

    2016-03-01

    Electrophoretic deposition (EPD) is a facile and feasible technique to prepare functional nanocomposite coatings for application in orthopedic-related implants. In this work, a ternary graphene oxide-chitosan-hydroxyapatite (GO-CS-HA) composite coating on Ti substrate was successfully fabricated by EPD. Coating microstructure and morphologies were investigated by scanning electron microscopy, contact angle test, Raman spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found GO-CS surface were uniformly decorated by HA nanoparticles. The potentiodynamic polarization test in simulated body fluid indicated that the GO-CS-HA coatings could provide effective protection of Ti substrate from corrosion. This ternary composite coating also exhibited good biocompatibility during incubation with MG63 cells. In addition, the nanocomposite coatings could decrease the attachment of Staphylococcus aureus.

  1. The facile and low temperature synthesis of nanophase hydroxyapatite crystals using wet chemistry.

    PubMed

    Dhand, Vivek; Rhee, K Y; Park, Soo-Jin

    2014-03-01

    A simple and facile wet chemistry route was used to synthesize nanophase hydroxyapatite (HaP) crystals at low temperature. The synthesis was carried out at a pH of 11.0 and at a temperature of 37°C. The resulting samples were washed several times and subjected to further analysis. XRD studies revealed that the HaP crystals were polycrystalline in nature with a crystallite size of ~15-60 ± 5 nm. SEM-EDXA images confirmed the presence of calcium (Ca), phosphorous (P), and oxygen (O) peaks. Likewise, FTIR confirmed the presence of characteristic phosphate and hydroxyl peaks in samples. Lastly, HRTEM images clearly showed distinctive lattice fringes positioned in the 100 and 002 planes. TGA analysis shows that HaP crystals can withstand higher calcination temperatures and are thermally stable.

  2. Synthesis and characterization of nanoporous hydroxyapatite using cationic surfactants as templates

    SciTech Connect

    Li Yanbao; Tjandra, Wiliana; Tam, Kam C.

    2008-08-04

    Nanoporous hydroxyapatite was synthesized utilizing cationic surfactants as templates. The effects of cetyltrimethylammonium bromide and reaction temperatures on the phase and morphology of HA were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The thermal stability of nanoporous structures was studied by XRD and thermal analyzers (TGA/DTA), while the pore structure of HA was observed using high resolution TEM. It was found that the pore size was about 1 nm, and the pore structure of HA was thermally stable up to 700 deg. C and the pore size did not change with reaction temperature and CTAB:PO{sub 4}{sup 3-} ratio. The possible formation mechanism of nanoporous structure was proposed.

  3. Characterization of the flow behavior of alginate/hydroxyapatite mixtures for tissue scaffold fabrication.

    PubMed

    Tian, X Y; Li, M G; Cao, N; Li, J W; Chen, X B

    2009-12-01

    Mixtures of alginate and hydroxyapatite (HA) are promising materials for biomedical applications such as the fabrication of tissue scaffolds. In this paper, the flow behavior of alginate/HA mixtures was investigated and determined to be dependent on the concentration of both alginate and HA, and temperature. The relationships were mathematically established and verified with experimental results. As applied to the tissue scaffold fabrication, the flow rate of the biomaterial solution was predicted from the established flow behavior and verified by experiments. On this basis, the moving speed of the needle was determined and used in the tissue scaffold fabrication. The results obtained show that the knowledge of the flow behavior is essential to the fabrication of tissue scaffolds with an interconnected microstructure.

  4. Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying; Cheng, Yan; Zheng, Yufeng; Xi, Tingfei; Wei, Shicheng

    2013-11-01

    Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

  5. Long-term in vivo experimental investigations on magnesium doped hydroxyapatite bone substitutes.

    PubMed

    Sartori, M; Giavaresi, G; Tschon, M; Martini, L; Dolcini, L; Fiorini, M; Pressato, D; Fini, M

    2014-06-01

    Despite several efforts to find suitable alternatives to autologous bone, no bone substitute currently available provides the same characteristics and properties. Nevertheless, among the wide range of materials proposed as bone substitutes, calcium phosphate materials represent the most promising category and the present study is aimed at improving the knowledge on non-stoichiometric magnesium-doped hydroxyapatite substitutes (Mg-HA), tested in two different formulations: Mg-HA Putty and Mg-HA Granules. These bone substitutes were implanted bilaterally into iliac crest bone defects in healthy sheep and comparative histological, histomorphometric, microhardness and ultrastructural assessments were performed 9, 12, 18 and 24 months after surgery to elucidate bone tissue apposition, mineralization and material degradation in vivo. The results confirmed that the biomimetic bone substitutes provide a histocompatible and osteoconductive structural support, during the bone formation process, and give essential information about the in vivo resorption process and biological behavior of biomimetic bone substitutes.

  6. Behavior of Plasma-Sprayed Hydroxyapatite Coatings onto Carbon/carbon Composites in Simulated Body Fluid

    NASA Astrophysics Data System (ADS)

    Sui, Jin-Ling; Bo, Wu; Hai, Zhou; Cao, Ning; Li, Mu-Sen

    Two types of hydroxyapatite (HA) coatings onto carbon/carbon composite (C/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the amorphous HA do dissolve slightly, and the dissolution of CaO phases in SBF was evident after 1 day of soaking. The calcium-ion concentration was decreased and the pH value of SBF was increased with the increasing of the immersing time. The precipitation was mainly composed of HA, which was verified by X-ray diffraction (XRD) and electron-probe microanalyzer.

  7. A novel jet-based nano-hydroxyapatite patterning technique for osteoblast guidance

    PubMed Central

    Li, Xiang; Koller, Garrit; Huang, Jie; Di Silvio, Lucy; Renton, Tara; Esat, Minoo; Bonfield, William; Edirisinghe, Mohan

    2010-01-01

    Surface topography is well known to play a crucial role in influencing cellular responses to an implant material and is therefore important in bone tissue regeneration. A novel jet-based patterning technique, template-assisted electrohydrodynamic atomization spraying, was recently devised to control precisely the surface structure as well as its dimensions. In the present study, a detailed investigation of this patterning process was carried out. A range of nano-hydroxyapatite (nHA) line-shaped patterns <20 µm in width were successfully deposited on a commercially pure Ti surface by controlling the flow of an nHA suspension in an electric field. In vitro studies showed that the nHA patterns generated are capable of regulating the human osteoblast cell attachment and orientation. PMID:19493897

  8. Development and characterization of porous silver-incorporated hydroxyapatite ceramic for separation and elimination of microorganisms.

    PubMed

    Yang, Lei; Ning, Xiaoshan; Xiao, Qunfang; Chen, Kexin; Zhou, Heping

    2007-04-01

    A novel filter material for separating and eliminating microorganisms in water and gas was fabricated by incorporating silver ions into porous hydroxyapatite (HA) ceramics prepared by a starch additive technique. The porous ceramics reveal a microstructure of both large and small pores. Microorganism separating and eliminating properties of the porous silver-incorporated HA ceramics (PHA-Ag) were investigated by bacterial and viral filtration tests. The PHA-Ag demonstrated excellent separating and antibacterial effects on Escherichia coli and the mechanisms were studied. Adsorption of bacterial cells to the HA and the barricading effect of small pores contribute to the separating property of PHA-Ag, while the Ag+ ions equip the ceramics with antibacterial property. Furthermore, the PHA-Ag exhibited an observable virus-eliminating property and its probable mechanism was also discussed.

  9. Signaling pathways of immobilized FGF-2 on silicon-substituted hydroxyapatite.

    PubMed

    de la Concepción Matesanz, María; Feito, María José; Ramírez-Santillán, Cecilia; Lozano, Rosa María; Sánchez-Salcedo, Sandra; Arcos, Daniel; Vallet-Regí, María; Portolés, María-Teresa

    2012-04-01

    Therapeutic strategies for bone regeneration involve the selection of suitable biomaterials, growth factors, and cell types to mimic the cellular microenvironment where molecular and mechanical signals control the reconstruction of bone tissue. The immobilization of basic fibroblast growth factor (FGF-2) on powdered silicon-substituted hydroxyapatite (Si-HA) allows to prepare a biofunctional biomaterial able to interact with bone cells in a very specific way. The biological activity of FGF-2/Si-HA, evaluated in Saos-2 osteoblasts and MC3T3-E1 preosteoblasts through the PLCγ and MAPK/ERK signal transduction pathways, shows that FGF-2 immobilized on Si-HA provides the right signals to cells stimulating crucial intracellular mechanisms of osteoblast proliferation and differentiation.

  10. Novel phosphorus-containing cyclodextrin polymers and their affinity for calcium cations and hydroxyapatite.

    PubMed

    Wintgens, Véronique; Dalmas, Florent; Sébille, Bernard; Amiel, Catherine

    2013-10-15

    Novel phosphorous-containing β-cyclodextrin (βCD) polymers (CDP) were synthesized easily under "green chemistry" conditions. A simple polycondensation between the hydroxyl groups of βCD and non-toxic sodium trimetaphosphate (STMP) under basic conditions led to soluble, non-reticulated CDPs with molecular weights (Mw) higher than 10(4) g mol(-1), the actual value depending on the NaOH:βCD and STMP:βCD weight ratios. The presence of both βCD and phosphate groups in the polymer allows for strong interactions with amphiphilic probes, such as 1-adamantyl acetic acid, or with divalent cations, such as Ca(2+), whose strengths were characterized by isothermal titration microcalorimetry. The obtained phosphated compounds also display high affinity towards hydroxyapatite (HA), leading to HA nanoparticles that could easily be recovered by CDPs, as demonstrated by transmission electron microscopy and quantitative determination of the total amount of phosphated molecules fixed on HA.

  11. Fiber taper coupling to chalcogenide microsphere modes

    SciTech Connect

    Grillet, Christian; Bian Shuning; Magi, Eric C.; Eggleton, Benjamin J.

    2008-04-28

    We report the fabrication and optical characterization of microsphere in chalcogenide (As{sub 2}Se{sub 3}). We show that high Q modes of a 9.2 {mu}m diameter chalcogenide glass can be efficiently excited via evanescent coupling using a silica tapered fiber. Loaded Q factors of more than 20 000 have been measured. Fine analysis of the coupling spectrum around 1619 nm led to an estimation of the microsphere eccentricity of less than 1%. Owing to the unique combination properties of chalcogenide glass and the microspheres geometry, we expect this architecture to offer an ideal environment for versatile applications on both the telecommunication and midinfrared wavelength windows.

  12. Trap state spectroscopy studies and wettability modification of hydroxyapatite nanobioceramics

    NASA Astrophysics Data System (ADS)

    Aronov, Daniel; Rosenman, Gil

    2007-02-01

    Sintered hydroxyapatite coatings on titanium-based implants demonstrate beneficial biocompatibility and osteoconductivity. It has been shown that charged surface states and bulk traps located in the vicinity of the surface of the hydroxyapatite coatings strongly influence wettability properties of the hydroxyapatite and may modify biocompatibility of these nanostructured bioceramics. Combination of high-resolution electron state spectroscopy methods, thermostimulated exoelectron emission, and thermoluminescence methods, applied in this work, have allowed studying electron trap energy spectrum of the hydroxyapatite bioceramics.

  13. Controlled growth and kinetics of porous hydroxyapatite spheres by a template-directed method

    NASA Astrophysics Data System (ADS)

    He, Qian Jun; Huang, Zhi Liang

    2007-03-01

    Porous hydroxyapatite (HA) spheres with high purity of phase and well-controlled pore size were grown by a template-directed method. We studied for the initial concentration of Ca-P how to control the chemical component of the products, and for the concentration of template how to control the aperture and the morphology of porous HA spheres. The experimental results indicated that the lower concentration of Ca-P was prone to pure HA phase and the aperture decreased gradually with the increase of the concentration of template. Correspondingly, the crystallization thermodynamics and template-directed growth kinetics were discussed in details. The solubility isotherms of HA and dicalcium phosphate (DCPD) were calculated based on classical crystallization theories of thermodynamics. The results suggested that there was a critical concentration of P=0.048 M in the case of Ca:P=5:3 and thus DCPD could be avoided only when P⩽0.048 M in this given reaction system. Kinetic analysis of HA crystal growth revealed that the template depressed the interfacial potential energy E, then enhanced the roughness on the surface of crystal nucleus and directed HA crystal to selectively grow along the [0 0 0 1] direction, and consequently governed the aperture of porous HA spheres. The experimental results were in agreement with the theoretical analysis.

  14. Effect of nano-hydroxyapatite reinforcement in mechanically alloyed NiTi composites for biomedical implant.

    PubMed

    Akmal, Muhammad; Raza, Ahmad; Khan, Muhammad Mudasser; Khan, M Imran; Hussain, Muhammad Asif

    2016-11-01

    Equi-atomic NiTi alloy composites reinforced with 0, 2, 4 and 6vol.% nano-hydroxyapatite (HA) were successfully synthesized using pressureless sintering. Pure Ni and Ti elements were ball milled for 10h in order to produce a mechanically alloyed equi-atomic NiTi alloy (MA-NiTi). Mechanically alloyed NiTi and HA powders were blended, compacted and then sintered for 3h at 1325K. The sintered density varied inversely with volume percent of HA reinforcement. The X-Ray diffraction spectra and SEM images showed the formation of multiple phases like NiTi, NiTi2, Ni3Ti, and Ni4Ti3. The back scattered-SEM image analysis confirmed the presence of Ni-rich and Ti-rich phases with increasing HA content. The 6vol.% HA reinforced composite showed Ni3Ti as the major phase having the highest hardness value which can be attributed to the presence of relatively harder phases along with higher HA content as a reinforcement. The composite of MA-NiTi with 2vol.% HA manifested the most desirable results in the form of better sintering density mainly due to the minute decomposition of NiTi into other phases. Therefore, the 2vol.% reinforced MA-NiTi composite can be exploited as a novel material for manufacturing biomedical implants.

  15. A further insight into the adsorption mechanism of protein on hydroxyapatite by FTIR-ATR spectrometry

    NASA Astrophysics Data System (ADS)

    Lin, Zhongyu; Hu, Ren; Zhou, Jianzhang; Ye, Yiwen; Xu, Zhaoxi; Lin, Changjian

    2017-02-01

    The adsorption mechanism of bovine serum albumin (BSA) on hydroxyapatite (HA) for different time intervals has been studied by Fourier transform infrared (FTIR)-attenuated total internal reflectance (ATR) spectrometry in this paper. The difference spectra obtained in HA and BSA frequency regions demonstrate that the binding of Pdbnd O, from the phosphate (PO43 -) of HA, to the hydrogen of methyl (- CH3), methene (- CH2) and amideII (- CNH) in the protein appears to be much faster and stronger than that of the Psbnd O group. In addition, Ca2 + must serve as a key role in the interaction of BSA with HA. The binding of Ca2 + to the oxygen of the peptide bond seems to induce a significant reconformation of polypeptide backbones from β-pleated sheet to α-helix and β-turn of helical circles. This alteration seems to have been accompanied by much hydrogen of polypeptides driven to bind PO43 - and OH- of the HA actively and much -C = O and Hsbnd Nsbnd groups of the peptide bond freed from inter-chain hydrogen bonding to react on Ca2 + and combine strongly with the HA surface. This might be well expected to promote the HA biomineralization.

  16. Osteoinductive silk fibroin/titanium dioxide/hydroxyapatite hybrid scaffold for bone tissue engineering.

    PubMed

    Kim, Jung-Ho; Kim, Dong-Kyu; Lee, Ok Joo; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Lee, Jun Ho; Park, Chan Hum

    2016-01-01

    The present study demonstrated the fabrication that incorporation of titanium isopropoxide (TiO2) and hydroxyapatite (HA) nanoparticles into the silk fibroin (SF) scaffolds. In this process, we prepared TiO2 nanoparticles using sol-gel synthesis and the porous structure was developed by salt-leaching process. Homogeneous distribution of TiO2 and HA nanoparticles were confirmed by images of VP-FE-SEM and those equipped with energy dispersive X-ray spectrometer. Structural characteristics of the porous SF/TiO2/HA hybrid scaffold were also determined using FTIR analysis and X-ray diffractometer. In this study, the porous SF/TiO2/HA hybrid scaffold showed similar porosity, enhanced mechanical property, but decreased water binding abilities, compared with the porous SF scaffold. For evaluation of the osteogenic differentiation of rat bone marrow mesenchymal stem cells, alkaline phosphatase activity and osteogenic gene expression were employed. Our results revealed that the porous SF/TiO2/HA hybrid scaffold had improved osteoinductivity compared with the porous SF scaffold. These results suggest that the osteogenic property as well as mechanical property of the porous SF/TiO2/HA hybrid scaffold could be better than the porous SF scaffold. Therefore, the porous SF/TiO2/HA hybrid scaffold may be a good promising biomaterial for bone tissue engineering application.

  17. Effect of nano-hydroxyapatite on the axonal guidance growth of rat cortical neurons

    NASA Astrophysics Data System (ADS)

    Liu, Meili; Zhou, Gang; Song, Wei; Li, Ping; Liu, Haifeng; Niu, Xufeng; Fan, Yubo

    2012-05-01

    Nanomaterials such as carbon nanotubes (CNT) can improve axonal connecting in a target direction during regeneration, however, it is limited by the neurotoxicity of CNT. Here we investigate the possible protective effect of nano-hydroxyapatite (n-HA) against nerve injury, as well as CNT in cultured rat cortical neurons. In this study the nanomaterials were characterized by X-Ray diffractometry (XRD) and atomic force microscopy (AFM) analysis. Our results showed that axonal migration and extension were increased significantly after n-HA treatment by immunocytochemistry assay. The patch clamp assay results showed that n-HA acts protectively after nerve injury, which inhibited the average amplitude and frequency of excitatory postsynaptic currents (EPSCs). n-HA is not neurotoxic for the electrophysiology activity of cells. To find the effect of n-HA on axonal guidance growth in the cultured cortical neurons, Netrin 1, one of the axonal guidance cues, was determined by RT-PCR and western blot assay. Compared to the control group, n-HA down-regulated the mRNA level of netrin 1, and moreover, the expression of netrin 1 decreased significantly in the cells. n-HA caused the axonal guidance growth to be mediated by netrin 1 during nerve regeneration. Therefore, the data from the present study provided a new approach for the therapy or prevention of nerve injury.

  18. Hydroxyapatite/titania sol-gel coatings on titanium-zirconium alloy for biomedical applications.

    PubMed

    Wen, C E; Xu, W; Hu, W Y; Hodgson, P D

    2007-05-01

    A simple sol-gel method was developed for hydroxyapatite/titania (HA/TiO(2)) coatings on non-toxic titanium-zirconium (TiZr) alloy for biomedical applications. The HA/TiO(2)-coated TiZr alloy displayed excellent bioactivity when soaked in a simulated body fluid (SBF) for an appropriate period. Differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy-energy dispersive spectrometry were used to characterize the phase transformations and the surface structures and to assess the in vitro tests. The HA/TiO(2) layers were spin-coated on the surface of TiZr alloy at a speed of 3000rpm for 15s, followed by a heat treatment at 600 degrees C for 20min in an argon atmosphere sequentially. The TiO(2) layer exhibited a cracked surface and an anatase structure and the HA layer displayed a uniform dense structure. Both the TiO(2) and HA layers were 25microm thick, and the total thickness of the HA/TiO(2) coatings was 50microm. The TiZr alloy after the above HA/TiO(2) coatings displayed excellent bone-like apatite-forming ability when soaked in SBF and can be anticipated to be a promising load-bearing implant material.

  19. Preparation and characterization of bionic bone structure chitosan/hydroxyapatite scaffold for bone tissue engineering.

    PubMed

    Zhang, Jiazhen; Nie, Jingyi; Zhang, Qirong; Li, Youliang; Wang, Zhengke; Hu, Qiaoling

    2014-01-01

    Three-dimensional oriented chitosan (CS)/hydroxyapatite (HA) scaffolds were prepared via in situ precipitation method in this research. Scanning electron microscopy (SEM) images indicated that the scaffolds with acicular nano-HA had the spoke-like, multilayer and porous structure. The SEM of osteoblasts which were polygonal or spindle-shaped on the composite scaffolds after seven-day cell culture showed that the cells grew, adhered, and spread well. The results of X-ray powder diffractometer and Fourier transform infrared spectrometer showed that the mineral particles deposited in the scaffold had phase structure similar to natural bone and confirmed that particles were exactly HA. In vitro biocompatibility evaluation indicated the composite scaffolds showed a higher degree of proliferation of MC3T3-E1 cell compared with the pure CS scaffolds and the CS/HA10 scaffold was the highest one. The CS/HA scaffold also had a higher ratio of adhesion and alkaline phosphate activity value of osteoblasts compared with the pure CS scaffold, and the ratio increased with the increase of HA content. The ALP activity value of composite scaffolds was at least six times of the pure CS scaffolds. The results suggested that the composite scaffolds possessed good biocompatibility. The compressive strength of CS/HA15 increased by 33.07% compared with the pure CS scaffold. This novel porous scaffold with three-dimensional oriented structure might have a potential application in bone tissue engineering.

  20. Reinforced Pulsed Laser-Deposited Hydroxyapatite Coating on 316 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Bajpai, Shubhra; Gupta, Ankur; Pradhan, Siddhartha Kumar; Mandal, Tapendu; Balani, Kantesh

    2014-10-01

    Hydroxyapatite (HA) is a widely used bioceramic known for its chemical similarity with that of bone and teeth (Ca/P ratio of 1.67). But, owing to its extreme brittleness, α-Al2O3 is reinforced with HA and processed as a coating via pulsed laser deposition (PLD). Reinforcement of α-Al2O3 (50 wt.%) in HA via PLD on 316L steel substrate has shown modulus increase by 4% and hardness increase by 78%, and an improved adhesion strength of 14.2 N (improvement by 118%). Micro-scratching has shown an increase in the coefficient-of-friction from 0.05 (pure HA) to 0.17 (with 50 wt.% Al2O3) with enhancement in the crack propagation resistance (CPR) up to 4.5 times. Strong adherence of PLD HA-Al2O3 coatings (~4.5 times than that of HA coating) is attributed to efficient release of stored tensile strain energy (~17 × 10-3 J/m2) in HA-Al2O3 composites, making it a potential damage-tolerant bone-replacement surface coating.

  1. Carbon Nanotubes in Nanocomposites and Hybrids with Hydroxyapatite for Bone Replacements

    PubMed Central

    Shin, Ueon Sang; Yoon, Il-Kyu; Lee, Gil-Su; Jang, Won-Cheoul; Knowles, Jonathan C.; Kim, Hae-Won

    2011-01-01

    Hydroxyapatite (HA), as a bone mineral component, has been an attractive bioceramic for the reconstruction of hard tissues. However, its poor mechanical properties, including low fracture toughness and tensile strength, have been a significant challenge to the application of HA for the replacement of load-bearing and/or large bone defects. Among materials studied to reinforce HA, carbon nanotubes (CNTs: single-walled or multiwalled) have recently gained significant attention because of their unprecedented mechanical properties (high strength and toughness) and physicochemical properties (high surface area, electrical and thermal conductivity, and low weight). Here, we review recent studies of the organization of HA-CNTs at the nanoscale, with a particular emphasis on the functionalization of CNTs and their dispersion within an HA matrix and induction of HA mineralization. The organization of CNTs and HA implemented at the nanoscale can further be developed in the form of coatings, nanocomposites, and hybrid powders to enable potential applications in hard tissue reconstruction. PMID:21776341

  2. Mechanistic investigation on microbial toxicity of nano hydroxyapatite on implant associated pathogens.

    PubMed

    Baskar, K; Anusuya, T; Devanand Venkatasubbu, G

    2017-04-01

    The use of atomic scale inorganic nanoparticles (NPs) to fight against pathogenic microorganisms is a recent trend in biomedical area which overcomes the limitations of organic compounds in terms of stability, shelf life and bioactivity. One such Calcium phosphate based biomaterial is hydroxyapatite (HA), considered as potential bioactive compound with excellent biocompatibility, osteointegrity and biodegradability. Osteomyelitis, the implant associated infection, is the major problem worldwide responsible for the majority of implant failure cases. Since HA is used as a coating material of implants, only few reports were available on its antimicrobial activity and cytotoxicity whereas no reports on its possible antimicrobial mechanism. In this present study, the HA-NPs were synthesized by wet chemical precipitation and were characterized using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The synthesized HA-NPs were evaluated for antimicrobial activity against implant associated bacterial pathogens. The study also explores the mechanistic action of HA-NPs in killing of bacteria by determining the reactive oxygen species (ROS) generation, DNA fragmentation, Lactate dehydrogenase (LDH) leakage and cellular interaction. In addition the cytotoxicity of HA-NPs was determined by MTT assay and Fluorescence Microscopic analysis. The results revealed that, the synthesized HA-NPs showed good antibacterial activity for tested bacterial species and the possible antibacterial mechanism were due to the lack of membrane integrity and cytotoxic studies shows the concentration dependent changes in cell viability.

  3. Fabrication and physico-mechanical properties of thin magnetron sputter deposited silver-containing hydroxyapatite films

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Surmeneva, M. A.; Tyurin, A. I.; Pirozhkova, T. S.; Shuvarin, I. A.; Prymak, O.; Epple, M.; Chaikina, M. V.; Surmenev, R. A.

    2016-01-01

    As a measure of the prevention of implant associated infections, a number of strategies have been recently applied. Silver-containing materials possessing antibacterial activity as expected might have wide applications in orthopedics and dentistry. The present work focuses on the physico-chemical characterization of silver-containing hydroxyapatite (Ag-HA) coating obtained by radio frequency (RF) magnetron sputtering. Mechanochemically synthesized Ag-HA powder (Ca10⿿xAgx(PO4)6(OH)2⿿x, x = 1.5) was used as a precursor for sputtering target preparation. Morphology, composition, crystallinity, physico-mechanical features (Young's modulus and nanohardness) of the deposited Ag-HA coatings were investigated. The sputtering of the nanostructured multicomponent target at the applied process conditions allowed to deposit crystalline Ag-HA coating which was confirmed by XRD and FTIR data. The SEM results revealed the formation of the coating with the grain morphology and columnar cross-section structure. The EDX analysis confirmed that Ag-HA coating contained Ca, P, O and Ag with the Ca/P ratio of 1.6 ± 0.1. The evolution of the mechanical properties allowed to conclude that addition of silver to HA film caused increase of the coating nanohardness and elastic modulus compared with those of pure HA thin films deposited under the same deposition conditions.

  4. Electrophoretic deposition of hydroxyapatite-CaSiO3-chitosan composite coatings.

    PubMed

    Pang, Xin; Casagrande, Travis; Zhitomirsky, Igor

    2009-02-15

    Electrophoretic deposition (EPD) method has been developed for the fabrication of hydroxyapatite (HA)-CaSiO(3) (CS)-chitosan composite coatings for biomedical applications. The use of chitosan enabled the co-deposition of HA and CS particles and offered the advantage of room temperature processing of composite materials. The coating composition was varied by the variation of HA and CS concentrations in the chitosan solutions. Cathodic deposits were obtained as HA-CS-chitosan monolayers, HA-chitosan/chitosan multilayers or functionally graded materials (FGM) containing HA-chitosan and CS-chitosan layers of different composition. The thickness of the individual layers was varied in the range of 0.1-20 microm. The deposition yield was studied at different experimental conditions and compared with the results of modeling. It was shown that the moving boundary model for the two component system can explain the non-linear increase in the deposition yield with increasing HA concentration in chitosan solutions. The obtained coatings were studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed that these coatings provided corrosion protection of stainless steel substrates in Ringer's physiological solution. The deposition mechanism and kinetics of deposition have been discussed.

  5. Characterization of a Polyamine Microsphere and Its Adsorption for Protein

    PubMed Central

    Wang, Feng; Liu, Pei; Nie, Tingting; Wei, Huixian; Cui, Zhenggang

    2013-01-01

    A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37–4.29 μm. The isoelectric point of the microsphere is 10.6. The microsphere can adsorb proteins through the co-effect of electrostatic and hydrophobic interactions. Among the proteins tested, the highest value of adsorption of microsphere, 127.8 mg·g−1 microsphere, was obtained with lipase. In comparison with other proteins, the hydrophobic force is more important in promoting the adsorption of lipase. The microsphere can preferentially adsorb lipase from an even mixture of proteins. The optimum temperature and pH for the selective adsorption of lipase by the microsphere was 35 °C and pH 7.0. PMID:23344018

  6. Comparison on mechanical properties of single layered and bilayered chitosan-gelatin coated porous hydroxyapatite scaffold prepared through freeze drying method

    NASA Astrophysics Data System (ADS)

    Effendi, M. D.; Gustiono, D.; Lukmana; Ayu, D.; Kurniawati, F.

    2017-02-01

    Biopolymer coated porous hydroxyapatite (HA) scaffolds were prepared for tissue engineering trough freeze drying method and impregnation. in this study, to mimic the mineral and organic component of natural bone, synthetic hydroxapatite (HA) scaffolds coated by polymer were prepared. Highly porous Hap scaffolds, fabricated by synthetic HA impregnation method on polyurethane foam, were coated with polymer coating solution, consisting of chitosan, Gelatin, and bilayered chitosan-gelatin prepared by aging and impregnating technique. For the purpose of comparison, The bare scaffolds without polymer coating layer were investigated. The Bare scaffolds were highly porous and interconnected with a pore size of around 150 µm–714 µm, has porosity at around 67,7% -85,7%, and has mechanical strength at around 0.06 Mpa - 0.071 Mpa, which is suitable for osteoblast cell Proliferation. Chitosan coated porous HA scaffold and gelatin coated porous HA scaffold had mechanical strength at around 0.81-0.85 Mpa, and 1.32-1.34 Mpa, respectively, with weight ratio of biopolymer and Hap was around 18%-22%. To compare these results, the coating on the bare scaffold with gelatin and chitosan had been conducted. Based on the result of FTIR, it could be concluded that coating procedure applied on porous hydroxy apatite (HA) coated by gelatin, chitosan coated HA scaffold, and bilayered Gelatin-chitosan coated porous HA scaffold, confirming that for allsampleshad no significant chemical effect on the coating structure. The compressive strength of bilayered Gelatin-chitosan coated HA scaffold had middle values between the rest, at around 1,06-1.2 Mpa for the samples at the same weight ratio of biopolymer: HA (around 18% - 22%). These results also confirming that coating by gelatin on porous hydroxyapatite was highest compresive strength and can be applied to improve mechanical properties of porous hydroxyapatite bare scaffold

  7. An innovative technique to simply fabricate ZrO₂-HA-TiO₂ nanostructured layers.

    PubMed

    Samanipour, F; Bayati, M R; Golestani-Fard, F; Zargar, H R; Troczynski, T; Mirhabibi, A R

    2011-08-01

    For the first time, ZrO₂-HA-TiO₂ layers were synthesized through EPD-Enhanced MAO (EEMAO) technique in only one step where no supplementary treatment was required. SEM, XRD, EDX, and XPS techniques were employed to propose a correlation between the growth parameters and the physical and chemical properties of the layers. The layers revealed a porous structure where applying higher voltages and/or utilizing higher concentrated electrolytes resulted in formation of wider pores and increasing the zirconium concentration in the layers; meanwhile, prolonging the growth time had the same effects. The layers mainly consisted of anatase, hydroxyapatite, monoclinic ZrO₂, and tetragonal ZrO₂ phases. Increasing the voltage, electrolyte concentration, and time, hydroxyapatite as well as tetragonal ZrO₂ was decomposed to α-TCP, monoclinic ZrO₂, and ZrO. The nanosized zirconia particles (d = 20-60 nm) were further accumulated on the vicinity of the layers when thicker electrolytes were utilized or higher voltages were applied. Emphasizing on the chemical and electrochemical foundations, a probable formation mechanism was finally put forward.

  8. Prediction of mechanical properties of composites of HDPE/HA/EAA.

    PubMed

    Albano, C; Perera, R; Cataño, L; Karam, A; González, G

    2011-04-01

    In this investigation, the behavior of the mechanical properties of composites of high-density polyethylene/hydroxyapatite (HDPE/HA) with and without ethylene-acrylic acid copolymer (EAA) as possible compatibilizer, was studied. Different mathematical models were used to predict their Young's modulus, tensile strength and elongation at break. A comparison with the experimental results shows that the theoretical models of Guth and Kerner modified can be used to predict the Young's modulus. On the other hand, the values obtained by the Verbeek model do not show a good agreement with the experimental data, since different factors that influence the mechanical properties are considered in this model such as: aspect ratio of the reinforcement, interfacial adhesion, porosity and binder content. TEM analysis confirms the discrepancies obtained between the experimental Young's modulus values and those predicted by the Verbeek model. The values of "P", "a" and "σ(A)" suggest that an interaction among the carboxylic groups of the copolymer and the hydroxyl groups of hydroxyapatite might be present. In composites with 20 and 30 wt% of filler, this interaction does not improve the Young's modulus values, since the deviations of the Verbeek model are significant.

  9. Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

    SciTech Connect

    Mohd, S. M.; Abd, M. Z.; Abd, A. N.

    2010-03-11

    The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

  10. Mechanical properties of calcium sulphate/hydroxyapatite cement.

    PubMed

    Lei, Dang; Wardlaw, D; Hukins, D W L

    2006-01-01

    Setting times, volume after setting, injectability and hardness (at 37 degrees C in contact with Ringer's solution) were determined for cements made of mixtures of calcium sulphate hemihydrate (CS) and hydroxyapatite (HA) with a range of compositions. The purpose of these experiments was to determine the behaviour of a mixture that could be used as an injectable cement for orthopaedic applications, including spinal fusion. A suitable mixture consisted of 60% CS and 40% HA by mass; a slurry was made by mixing solid (36 g) with water (15 cm(3)). The slurry had initial and final setting times of 5.7+/-1.3 min and 19.6+/-0.7 min (mean +/- standard deviation), respectively. The hardness of the cement did not systematically increase or decrease in the 72 h following the final setting time. The volume of the cement was 99.8+/-0.4% of the volume of the initial slurry, i.e. there was negligible shrinkage on setting. It was able to withstand a pressure of 7.3+/-1.2 MPa, applied by a hemispherical indenter before the onset of permanent damage, indicating adequate strength for spinal fusion.

  11. Porous Hydroxyapatite Scaffold with Three-Dimensional Localized Drug Delivery System Using Biodegradable Microspheres

    DTIC Science & Technology

    2011-03-21

    such as hydroxyapa- tite [(Ca10(PO4)6(OH)2), HAp] is known for its excellent biocompat- ibility due to its similarity in composition to the apatite ...were radio- frequency (RF) plasma glow-discharged (PDC-32 G, Harrick Plasma, USA) in oxygen -filled chamber at a pressure of 200 mTorr Pa and at 40 mA...The plasma power density and the treatment time were fixed at 30 W and 30 s, respectively. The second step involved dispersing the oxygen plasma

  12. Silver-Containing Hydroxyapatite Coating Reduces Biofilm Formation by Methicillin-Resistant Staphylococcus aureus In Vitro and In Vivo

    PubMed Central

    Miyamoto, Hiroshi; Shobuike, Takeo; Kobatake, Tomoki; Mawatari, Masaaki

    2016-01-01

    Biofilm-producing bacteria are the principal causes of infections associated with orthopaedic implants. We previously reported that silver-containing hydroxyapatite (Ag-HA) coatings exhibit high antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). In the present study, we evaluated the effects of Ag-HA coating of implant surfaces on biofilm formation. Titanium disks (14-mm diameter, 1-mm thickness), one surface of which was coated with HA or 0.5%–3.0% Ag-HA with a thermal spraying technique, were used. In vitro, the disks were inoculated with an MRSA suspension containing 4 × 105 CFU and incubated for 1-2 weeks. In vivo, MRSA-inoculated HA and 3% Ag-HA disks (8.8–10.0 × 108 CFU) were implanted subcutaneously on the back of rats for 1–7 days. All disks were subsequently stained with a biofilm dye and observed under a fluorescence microscope, and biofilm coverage rates (BCRs) were calculated. The BCRs on the Ag-HA coating were significantly lower than those on the HA coating at all time points in vitro (p < 0.05). Similar results were observed in vivo (p < 0.001) without argyria. Ag-HA coating reduced biofilm formation by MRSA in vitro and in vivo; therefore, Ag-HA coating might be effective for reducing implant-associated infections. PMID:28105433

  13. In vivo antibacterial and silver-releasing properties of novel thermal sprayed silver-containing hydroxyapatite coating.

    PubMed

    Shimazaki, Takafumi; Miyamoto, Hiroshi; Ando, Yoshiki; Noda, Iwao; Yonekura, Yutaka; Kawano, Shunsuke; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao

    2010-02-01

    One of the serious postoperative complications associated with joint replacement is bacterial infection. In addressing this problem, we have previously described the development of a novel thermal spraying technology combining silver (Ag) showing antibacterial activity with hydroxyapatite (HA) displaying good biocompatibility and osteoconductivity, and reported the in vitro properties. This study evaluated serum Ag ion concentrations and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) using a subcutaneous rat model. HA loaded with 3 wt % of silver oxide (Ag-HA) and plain HA were sprayed on the surface of titanium disks. Ag-HA- or HA-coated samples were implanted into the back subcutaneous pockets of male Sprague-Dawley rats. Mean serum Ag ion concentration in the Ag-HA group increased to more than 50 ppb by 48 h after implantation, then decreased gradually to baseline levels. Mean (+/- standard error of the mean) number of viable MRSA on HA coating was (1.5 +/- 0.5) x 10(5), which is significantly more than the (1.1 +/- 0.4) x 10(4) on Ag-HA coating (p < 0.001). Ag-HA coating offers good abilities to release Ag ions and kill MRSA in vivo.

  14. Acute and Subacute Toxicity In Vivo of Thermal-Sprayed Silver Containing Hydroxyapatite Coating in Rat Tibia

    PubMed Central

    Tsukamoto, Masatsugu; Miyamoto, Hiroshi; Ando, Yoshiki; Eto, Shuichi; Akiyama, Takayuki; Yonekura, Yutaka; Mawatari, Masaaki

    2014-01-01

    To reduce the incidence of implant-associated infection, we previously developed a novel coating technology using hydroxyapatite (HA) containing silver (Ag). This study examined in vivo acute and subacute toxicity associated with the Ag-HA coating in rat tibiae. Ten-week-old rats received implantation of HA-, 2% Ag-HA-, or 50% Ag-HA-coated titanium rods. Concentrations of silver in serum, brain, liver, kidneys, and spleen were measured in the acute phase (2–4 days after treatment) and subacute phase (4–12 weeks after treatment). Biochemical and histological examinations of those organs were also performed. Mean serum silver concentration peaked in the acute phase and then gradually decreased. Mean silver concentrations in all examined organs from the 2% Ag-HA coating groups showed no significant differences compared with the HA coating group. No significant differences in mean levels of glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, lactate dehydrogenase, creatinine, or blood urea nitrogen were seen between the three groups and controls. Histological examinations of all organs revealed no abnormal pathologic findings. No acute or subacute toxicity was seen in vivo for 2% Ag-HA coating or HA coating. Ag-HA coatings on implants may represent biologically safe antibacterial biomaterials and may be of value for reducing surgical-site infections related to implantation. PMID:24779019

  15. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1996-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  16. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1996-04-16

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  17. Characterization of hydroxyapatite whisker reinforced composites and scaffolds for mechanical and biological function in orthopaedic and spinal implants

    NASA Astrophysics Data System (ADS)

    Conrad, Timothy L.

    The overall objective of this study was to investigate the mechanical and biological properties of HA whisker reinforced polyaryletherketone (PAEK) composites and scaffolds which are key to clinical translation for orthopedic and spinal implants. The fatigue behavior of polyetherketoneketone (PEKK) reinforced with 0, 20, and 40 vol% hydroxyapatite (HA) was investigated in four-point bending fatigue. The fatigue life decreased with increasing HA reinforcement. However, PEKK reinforced with 40 vol% HA whiskers exhibited a fatigue life greater than 2.106 cycles at 40 MPa. Moreover, HA whisker reinforcement resulted in decreased creep deformation and minimal modulus degradation. The effects of the mold temperature and polyetheretherketone (PEEK) powder were investigated on the mechanical properties and crystallinity of HA whisker reinforced PEEK scaffolds prepared using compression molding and porogen leaching. The mechanical properties of the scaffolds increased while the PEEK crystallinity decreased, with increasing mold temperature and suggested an optimal mold temperature of 370--375°C for PEEK scaffolds comprising of 75% porosity and 20 vol% HA whisker reinforcement, regardless of the PEEK powder size. The effects of the porogen morphology on the architecture, mechanical properties, and permeability of HA whisker reinforced PEEK scaffolds were investigated in 75--90% porous scaffolds. HA whisker reinforced PEEK scaffolds prepared with an ellipsoidal porogen exhibited a greater permeability than scaffolds prepared with a cubic porogen. The compressive modulus, yield strength, and yield strain were not affected by the porogen morphology. The effects of HA reinforcement morphology and content was investigated on the behavior of primary osteoblasts on dense HA reinforced PEEK substrates in vitro. At day 7, the number of osteoblasts attached to PEEK substrate surfaces increased with increasing HA content and for HA whiskers compared to equiaxed HA powder reinforcement

  18. Hydrothermal synthesis of hydroxyapatite rods

    NASA Astrophysics Data System (ADS)

    Zhang, Xing; Vecchio, Kenneth S.

    2007-10-01

    Hydroxyapatite (HAP) rods were synthesized from dicalcium phosphate anhydrous (CaHPO 4, DCPA) and calcium carbonate (CaCO 3) by the hydrothermal method from 120 to 180 °C. Both cuttlebone (aragonite polymorph of CaCO 3) and CaCO 3 chemical (calcite polymorph of CaCO 3) were used as CaCO 3 sources. The nucleation and growth of HAP rods mainly occurred on DCPA particles, while some HAP rods also grew from aragonite particles. The nucleation and growth of β-tricalcium phosphate (β-TCP) particles on the surface of calcite particles were observed at the beginning of the reaction of DCPA and calcite, and some HAP rods were also found to grow out of β-TCP particles. After the hydrothermal reaction at 140 °C for 24 h, most products are HAP with a small amount of β-TCP synthesized as a byproduct. The HAP rods synthesized were ˜200 nm in width and several microns in length. The reaction mechanism and growth process of HAP rods are discussed.

  19. Hydroxyapatite nanocrystals functionalized with alendronate as bioactive components for bone implant coatings to decrease osteoclastic activity

    NASA Astrophysics Data System (ADS)

    Bosco, Ruggero; Iafisco, Michele; Tampieri, Anna; Jansen, John A.; Leeuwenburgh, Sander C. G.; van den Beucken, Jeroen J. J. P.

    2015-02-01

    The integration of bone implants within native bone tissue depends on periprosthetic bone quality, which is severely decreased in osteoporotic patients. In this work, we have synthesized bone-like hydroxyapatite nanocrystals (nHA) using an acid-base neutralization reaction and analysed their physicochemical properties. Subsequently, we have functionalized the nHA with alendronate (nHAALE), a well-known bisphosphonate drug used for the treatment of osteoporosis. An in vitro osteoclastogenesis test was carried out to evaluate the effect of nHAALE on the formation of osteoclast-like cells from monocytic precursor cells (i.e. RAW264.7 cell line) showing that nHAALE significantly promoted apoptosis of osteoclast-like cells. Subsequently, nHA and nHAALE were deposited on titanium disks using electrospray deposition (ESD), for which characterisation of the deposited coatings confirmed the presence of alendronate in nHAALE coatings with nanoscale thickness of about 700 nm. These results indicate that alendronate linked to hydroxyapatite nanocrystals has therapeutic potential and nHAALE can be considered as an appealing coating constituent material for orthopaedic and oral implants for application in osteoporotic patients.

  20. Development of high strength hydroxyapatite for bone tissue regeneration using nanobioactive glass composites

    NASA Astrophysics Data System (ADS)

    Shrivastava, Pragya; Dalai, Sridhar; Sudera, Prerna; Sivam, Santosh Param; Vijayalakshmi, S.; Sharma, Pratibha

    2013-02-01

    With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO2 70 mol%, CaO 26 mol % and P2O5 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulated Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bo