Science.gov

Sample records for hydroxyapatite ha microspheres

  1. Modified composite microspheres of hydroxyapatite and poly(lactide-co-glycolide) as an injectable scaffold

    NASA Astrophysics Data System (ADS)

    Hu, Xixue; Shen, Hong; Yang, Fei; Liang, Xinjie; Wang, Shenguo; Wu, Decheng

    2014-02-01

    The compound of hydroxyapatite-poly(lactide-co-glycolide) (HA-PLGA) was prepared by ionic bond between HA and PLGA. HA-PLGA was more stable than the simple physical blend of hydroxyapatite and poly(lactide-co-glycolide) (HA/PLGA). The surface of HA-PLGA microsphere fabricated by an emulsion-solvent evaporation method was rougher than that of HA/PLGA microspheres. Moreover, surface HA content of HA-PLGA microspheres was more than that of HA/PLGA microspheres. In vitro mouse OCT-1 osteoblast-like cell culture results showed that the HA-PLGA microspheres clearly promoted osteoblast attachment, proliferation and alkaline phosphatase activity. It was considered that surface rich HA component and rough surface of HA-PLGA microsphere enhanced cell growth and differentiation. The good cell affinity of the HA-PLGA microspheres indicated that they could be used as an injectable scaffold for bone tissue engineering.

  2. 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. PMID:26478351

  3. Characterization of hollow hydroxyapatite/copper microspheres prepared from the reduction of copper-modified hydroxyapatite by glucose.

    PubMed

    Li, Chengfeng; Liang, Jiaqing; Niu, Jinye; Liu, Shuguang; Li, Guochang; Bai, Jiahai; Zhang, Aijuan; Ding, Rui

    2011-01-01

    This study employed a co-precipitation method to synthesize copper-modified hydroxyapatite (HA) powders, where Cu(2+) ions had entered the structure of HA and occupied Ca(1) sites in the columns parallel to the c-axis. Through a hydrothermal treatment, hollow HA/copper (Cu(2)O and/or Cu) microspheres with core-shell structures were prepared in solutions containing glucose, sodium carbonate and sodium citrate. When prolonging the reduction time, Cu(2+) ions dissolved from copper-modified HA were reduced by glucose initially to Cu(+) ions and then to Cu atoms, which would precipitate as copper on the surface of HA. The formation of microspheres with hollow structures was explained by the Kirkendall effect which states that diffusion behaviors of ions were different for HA and copper precipitations. Hybrid HA/copper powders might find their applications in gas sensors, catalysts, electrodes and so on. PMID:21821600

  4. 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 6μm, a specific surface area of 40m(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 16nm. 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 200μm, 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 15days 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. PMID:27040244

  5. Hollow hydroxyapatite microspheres as a device for controlled delivery of proteins.

    PubMed

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

    2011-03-01

    Hollow hydroxyapatite (HA) microspheres were prepared by reacting solid microspheres of Li(2)O-CaO-B(2)O(3) glass (106-150 μm) in K(2)HPO(4) solution, and evaluated as a controlled delivery device for a model protein, bovine serum albumin (BSA). Reaction of the glass microspheres for 2 days in 0.02 M K(2)HPO(4) solution (pH = 9) at 37°C resulted in the formation of biocompatible HA microspheres with a hollow core diameter equal to 0.6 the external diameter, high surface area (~100 m(2)/g), and a mesoporous shell wall (pore size ≈ 13 nm). After loading with a solution of BSA in phosphate-buffered saline (PBS) (5 mg BSA/ml), the release kinetics of BSA from the HA microspheres into a PBS medium were measured using a micro bicinchoninic acid (BCA) protein assay. Release of BSA initially increased linearly with time, but almost ceased after 24-48 h. Modification of the BSA release kinetics was achieved by modifying the microstructure of the as-prepared HA microspheres using a controlled heat treatment (1-24 h at 600-900°C). Sustained release of BSA was achieved over 7-14 days from HA microspheres heated for 5 h at 600°C. The amount of BSA released at a given time was dependent on the concentration of BSA initially loaded into the HA microspheres. These hollow HA microspheres could provide a novel inorganic device for controlled local delivery of proteins and drugs. PMID:21290170

  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. PMID:26354246

  7. Preparation of Hydroxyapatite Coating on the Surface of Hollow Glass Microspheres Using a Biomimetic Process

    NASA Astrophysics Data System (ADS)

    Jiao, Yan; Yang, Hai-Ying; Zhang, Ying-Long; Duan, Rong-Shuai; Lu, Yu-Peng

    2014-07-01

    Microcarrier culture technology has attached more attention, especially for scale-up cell culture in the filed of tissue engineering. The present work introduces a microcarrier with hydroxyapatite (HA) on hollow glass microsphere. Hollow glass microspheres with a main composition of SiO2 (55-65 wt.%), Al2O3 (26-35 wt.%), were pretreated by NaOH, on which hydroxyapatite coating was deposited by biomimetic process. The phase composition and morphology were characterized by X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscope, field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HRTEM), respectively. The results showed that after immersion for 15 days in 1.5 SBF, the uniform and dense HA coating was formed and it has porous surface and low crystallinity.

  8. 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.

  9. 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.

  10. Hollow hydroxyapatite microspheres: a novel bioactive and osteoconductive carrier for controlled release of bone morphogenetic protein-2 in bone regeneration

    PubMed Central

    Xiao, Wei; Fu, Hailuo; Rahaman, Mohamed N.; Liu, Yonxing; Bal, B. Sonny

    2013-01-01

    The regeneration of large bone defects is a common and significant clinical problem. Limitations associated with existing treatments such as autologous bone grafts and allografts have increased the need for synthetic bone graft substitutes. The objective of this study was to evaluate the capacity of novel hollow hydroxyapatite (HA) microspheres to serve as a carrier for controlled release of bone morphogenetic-2 (BMP2) in bone regeneration. Hollow HA microspheres (106–150 μm) with a high surface area (>100 m2/g) and a mesoporous shell wall (pore size 10–20 nm) were created using a glass conversion technique. The release of BMP2 from the microspheres into a medium composed of diluted fetal bovine serum in vitro was slow, but it occurred continuously for over 2 weeks. When implanted in rat calvarial defects for 3 or 6 weeks, the microspheres loaded with BMP2 (1 μg/defect) showed a significantly better capacity to regenerate bone than those without BMP2. The amount of new bone in the defects implanted with the BMP2-loaded microspheres was 40% and 43%, respectively, at 3 and 6 weeks, compared to 13% and 17%, respectively, for the microspheres without BMP2. Coating the BMP2-loaded microspheres with a biodegradable polymer, poly(lactic-co-glycolic acid), reduced the amount of BMP2 released in vitro and, above a certain coating thickness, significantly reduced bone regeneration in vivo. The results indicate that these hollow HA microspheres could provide a bioactive and osteoconductive carrier for growth factors in bone regeneration. PMID:23747325

  11. 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

  12. Controlled degradation pattern of hydroxyapatite/calcium carbonate composite microspheres.

    PubMed

    Yang, Ning; Zhong, Qiwei; Zhou, Ying; Kundu, Subhas C; Yao, Juming; Cai, Yurong

    2016-06-01

    Hydroxyapatite (HAP) is widely used in clinic due to its good biocompatibility and osteoconductivity except for its slow degradation speed. In the present study, spherical calcium carbonate (CaCO3 ) is fabricated in the presence of silk protein sericin, which is transmuted into HAP microsphere in phosphate solution with the assistance of microwave irradiation. The effect of reaction conditions on the conversion of CaCO3 is investigated including reaction time, chemical composition of phosphate solution, and microwave power to get a series of HAP/CaCO3 composites. The degradation property of the composites is evaluated in vitro. Results show the degradation speed of the composite with higher HAP content is slower. The degradation rate of the composite could be changed effectively by modulating the proportion of HAP and CaCO3 . This work provides a feasible method for the preparation of spherical HAP/CaCO3 composite with controllable degradability. The composite thus obtained may be an ideal material for bone tissue engineering application. Microsc. Res. Tech. 79:518-524, 2016. © 2016 Wiley Periodicals, Inc. PMID:27037606

  13. Evaluation of bone regeneration in implants composed of hollow HA microspheres loaded with TGF– 1 in a rat calvarial defect model

    PubMed Central

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

    2012-01-01

    Implants that serve simultaneously as an osteoconductive matrix and as a device for local growth factor delivery may be required for optimal bone regeneration in some applications. In the present study, hollow hydroxyapatite (HA) microspheres (106–150 μm) in the form of three-dimensional (3D) scaffolds or individual (loose) microspheres were created using a glass conversion process. The capacity of the implants, with or without transforming growth factor- 1 (TGF- 1), to regenerate bone in a rat calvarial defect model was compared. The 3D scaffolds supported the proliferation and alkaline phosphatase activity of osteogenic MLO-A5 cells in vitro, showing their cytocompatibility. Release of TGF- 1 from the 3D scaffolds into phosphate-buffered saline ceased after 2–3 days when 30% of the growth factor was released. Bone regeneration in the 3D scaffolds and the individual microspheres increased with time from 6 to 12 weeks, but it was significantly higher (23%) in the individual microspheres than in the 3D scaffolds (15%) after 12 weeks. Loading with TGF-β1 (5 μg/defect) enhanced bone regeneration in the 3D scaffolds and individual microspheres after 6 weeks, but had little effect after 12 weeks. 3D scaffolds and individual microspheres with larger HA diameter (150–250 μm) showed better ability to regenerate bone. Based on these results, implants composed of hollow HA microspheres show promising potential as an osteoconductive matrix for local growth factor delivery in bone regeneration. PMID:23168225

  14. Fabrication of inorganic hydroxyapatite nanoparticles and organic biomolecules-dual encapsulated alginate microspheres.

    PubMed

    Wang, Yu-Pu; Liao, Yu-Te; Liu, Chia-Hung; Yu, Jiashing; Chen, Jung-Chih; Wu, Kevin C-W

    2015-01-01

    Inorganic hydroxyapatite nanoparticles (HANPs) and two kinds of organic biomolecules (i.e., fluorescent dye rhodamine 6G and protein lysozyme) were coencapsulated into alginate microspheres through an air dynamical atomization with optimized operation conditions. The synthesized microspheres have several advantages: HANP provides osteoconductivity and mechanical strength, rhodamine 6G (R6G) and lysozyme act as model drugs, and alginate provides excellent biocompatibility and carboxylate functionality. The results of fluorescent microscopic images indicated the successful dual encapsulation of HANPs and lysozyme inside the alginate microspheres. Furthermore, the results of 3- (4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay showed that the fabricated alginate microspheres could be uptaken by HepG2 without apparent cytotoxicity. The dual encapsulated alginate microspheres fabricated in this study show great potential in many biomedical applications. PMID:25939572

  15. 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. PMID:26218713

  16. Development of Nanolayer Hydroxyapatite (HA) on Titanium Alloy via Superplastic Deformation Method

    NASA Astrophysics Data System (ADS)

    Khalid, Hidayah Mohd; Jauhari, Iswadi; Dom, Adibah Haneem Mohamad

    2012-10-01

    In this work, hydroxyapatite (HA) is successfully embedded onto titanium alloy using the superplastic deformation method. An embedded layer of approximately 249 nm is obtained at a temperature of 1200 K (927 °C), strain rate of 1 × 10-4 s-1, and process duration of 90 minutes. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) analyses indicate that HA is retained after the embedment process, and a significant amount of titanium (Ti) is diffused into the HA, forming a dense HA/Ti composite layer. Wear tests under a simulated body fluids (SBF) condition show that the adherent strength of HA and the interfacial strength between the HA layer and substrate are superior compared with the nonsuperplastic sample.

  17. The Evaluation of Hydroxyapatite (HA) Coated and Uncoated Porous Tantalum for Biomedical Material Applications

    NASA Astrophysics Data System (ADS)

    Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

    2014-04-01

    Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

  18. 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.

  19. In Vivo Osteogenic Potential of Biomimetic Hydroxyapatite/Collagen Microspheres: Comparison with Injectable Cement Pastes.

    PubMed

    Cuzmar, Erika; Perez, Roman A; Manzanares, Maria-Cristina; Ginebra, Maria-Pau; Franch, Jordi

    2015-01-01

    The osteogenic capacity of biomimetic calcium deficient hydroxyapatite microspheres with and without collagen obtained by emulsification of a calcium phosphate cement paste has been evaluated in an in vivo model, and compared with an injectable calcium phosphate cement with the same composition. The materials were implanted into a 5 mm defect in the femur condyle of rabbits, and bone formation was assessed after 1 and 3 months. The histological analysis revealed that the cements presented cellular activity only in the margins of the material, whereas each one of the individual microspheres was covered with osteogenic cells. Consequently, bone ingrowth was enhanced by the microspheres, with a tenfold increase compared to the cement, which was associated to the higher accessibility for the cells provided by the macroporous network between the microspheres, and the larger surface area available for osteoconduction. No significant differences were found in terms of bone formation associated with the presence of collagen in the materials, although a more extensive erosion of the collagen-containing microspheres was observed. PMID:26132468

  20. In Vivo Osteogenic Potential of Biomimetic Hydroxyapatite/Collagen Microspheres: Comparison with Injectable Cement Pastes

    PubMed Central

    Manzanares, Maria-Cristina; Ginebra, Maria-Pau; Franch, Jordi

    2015-01-01

    The osteogenic capacity of biomimetic calcium deficient hydroxyapatite microspheres with and without collagen obtained by emulsification of a calcium phosphate cement paste has been evaluated in an in vivo model, and compared with an injectable calcium phosphate cement with the same composition. The materials were implanted into a 5 mm defect in the femur condyle of rabbits, and bone formation was assessed after 1 and 3 months. The histological analysis revealed that the cements presented cellular activity only in the margins of the material, whereas each one of the individual microspheres was covered with osteogenic cells. Consequently, bone ingrowth was enhanced by the microspheres, with a tenfold increase compared to the cement, which was associated to the higher accessibility for the cells provided by the macroporous network between the microspheres, and the larger surface area available for osteoconduction. No significant differences were found in terms of bone formation associated with the presence of collagen in the materials, although a more extensive erosion of the collagen-containing microspheres was observed. PMID:26132468

  1. Preparation and evaluation of a new radiopharmaceutical for radiosynovectomy, 111Ag-labelled hydroxyapatite (HA) particles.

    PubMed

    Chattopadhyay, Sankha; Vimalnath, K V; Saha, Sujata; Korde, Aruna; Sarma, H D; Pal, Sujit; Das, Malay K

    2008-03-01

    Many radionuclides, namely, 166Ho, 90Y, 165Dy, 32P, 198Au, 186Re, etc. have been used for radio-synovectomy. Silver-111 (T 1/2 7.45 d) can be produced in a nuclear reactor and is a potential therapeutic radionuclide decaying by beta(-) emission (92% E beta max=1.037MeV and 8% by beta(-) decay associated with emission of gamma-rays (E gamma=245.4keV, I gamma=1.33%; E gamma=342.1keV, I gamma=6.7%)). Because of the production feasibility and favourable nuclear properties, 111Ag may find use as a suitable radionuclide for radio-synovectomy. Hydroxyapatite (HA), Ca10(PO4)6(OH)2 is one of the preferred particulates for this application. In this work, [111Ag]Ag-HA particulates were successfully prepared with high-labelling yield ( approximately 97%) at various pH values. The radiochemical purity of the [111Ag]Ag-HA particles was 99.9%. Stability studies for 7 days showed that the [111Ag]Ag-HA particles retained their stability. gamma camera images at 15 min, 24h and 5 d after injection of the particles into rabbits revealed the retention of the activity in the synovial joints of the knee, thereby indicating excellent in vivo stability of [111Ag]Ag-HA particles. Therefore, [111Ag]Ag-HA particles would be a potential therapeutic agent in the management of arthritis. PMID:17951062

  2. Polyphosphazene/nano-hydroxyapatite composite microsphere scaffolds for bone tissue engineering.

    PubMed

    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

    2008-07-01

    The nontoxic, neutral degradation products of amino acid ester polyphosphazenes make them ideal candidates for in vivo orthopedic 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 degrees 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 microm. The 3-D 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

  3. 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

  4. 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

  5. Effect of interfacial serum proteins on melanoma cell adhesion to biodegradable poly(l-lactic acid) microspheres coated with hydroxyapatite.

    PubMed

    Shinto, Hiroyuki; Hirata, Takuya; Fukasawa, Tomonori; Fujii, Syuji; Maeda, Hayata; Okada, Masahiro; Nakamura, Yoshinobu; Furuzono, Tsutomu

    2013-08-01

    We have measured the interaction forces between a murine melanoma cell and a poly(l-lactic acid) (PLLA) microsphere coated with/without hydroxyapatite (HAp) nanoparticles (i.e., an HAp/PLLA or a bare PLLA microsphere) in a serum-free culture medium, using atomic force microscopy (AFM) with colloid probe technique, in order to investigate how the HAp-nanoparticle coating as well as interfacial serum proteins influence the cell-microsphere adhesion. The cell adhesion force of the HAp/PLLA microspheres was 1.4-fold stronger than that of the bare PLLA microspheres. When the microspheres were pretreated with a culture medium supplemented with 10% fetal bovine serum, the cell adhesion force of the HAp/PLLA microspheres was increased by a factor of 2.1; in contrast, no change was observed in the cell adhesion force of the bare PLLA microspheres before/after the pretreatment. Indeed, the cell adhesion force of the HAp/PLLA was 2.8-fold larger than that of the bare PLLA after the pretreatment. Additionally, we have investigated the effect of interfacial serum proteins on the zeta potentials of these microspheres. On the basis of the obtained results, possible mechanism of cell adhesion to the HAp/PLLA and bare PLLA microspheres in the presence/absence of the interfacial serum proteins is discussed. PMID:23524077

  6. Porous nano-HA/collagen/PLLA scaffold containing chitosan microspheres for controlled delivery of synthetic peptide derived from BMP-2.

    PubMed

    Niu, Xufeng; Feng, Qingling; Wang, Mingbo; Guo, Xiaodong; Zheng, Qixin

    2009-03-01

    It is advantageous to incorporate controlled growth factor delivery into tissue engineering strategies. The purpose of the present study was to develop a novel tissue engineering scaffold with the capability of controlled releasing BMP-2-derived synthetic peptide. Porous nano-hydroxyapatite/collagen/poly(L-lactic acid)/chitosan microspheres (nHAC/PLLA/CMs) composite scaffolds containing different quantities of chitosan microspheres (CMs) were prepared by a thermally induced phase separation method. Dioxane was used as the solvent for PLLA. Introduction of less than 30% of CMs (on PLLA weight basis) did not remarkably affect the morphology and porosity of the nHAC/PLLA/CMs scaffolds. However, as the microspheres contents increased to 50%, the porosity of the composite decreased rapidly. The compressive modulus of the composite scaffolds increased from 15.4 to 25.5 MPa, while the compressive strength increased from 1.42 to 1.63 MPa as the microspheres contents increased from 0% to 50%. The hydrolytic degradation and synthetic peptide release kinetics in vitro were investigated by incubation in phosphate buffered saline solution (pH 7.4). The results indicated that the degradation rate of the scaffolds was increased with the enhancement of CMs dosage. The synthetic peptide was released in a temporally controlled manner, depending on the degradation of both incorporated chitosan microspheres and PLLA matrix. In vitro bioactivity assay revealed that the encapsulated synthetic peptide was biologically active as evidenced by stimulation of rabbit marrow mesenchymal stem cells (MSCs) alkaline phosphatase (ALP) activity. The successful microspheres-scaffold system offers a new delivery method of growth factors and a novel scaffold design for bone regeneration. PMID:19100794

  7. Hydrothermal fabrication of porous hollow hydroxyapatite microspheres for a drug delivery system.

    PubMed

    Lai, Wen; Chen, Cen; Ren, Xiaoyuan; Lee, In-Seop; Jiang, Guohua; Kong, Xiangdong

    2016-05-01

    Porous hollow hydroxyapatite microspheres (PHHMs) are the promising biomaterials, owing to their excellent biocompatibility, biodegradability and bioactivity. PHHMs have been used as drug controlled carriers due to their advantages such as large drug loading capacity, nanochannels for drug loading and release and high specific surface area. In this study, PHHMs were prepared successfully in Na2HPO4 solution by an anion-exchange process using vaterite CaCO3 through a hydrothermal method. The previous vaterite CaCO3 was synthesized by a polymer-templated method in the poly(styrene sulfonic acid) sodium salt (PSS) aqueous solutions. The PHHMs have a size distribution from 0.8 to 2.0μm, with an average pore size of about 24.3nm. The wall of PHHMs is constructed with building units of hydroxyapatite nanofibers with an average length of 300nm and an average width of 20nm. The PHHMs displayed a high drug loading capacity and pH-responsive sustained-controlled drug release behavior when we used doxorubicin hydrochloride (DOX) as a loading drug. Moreover, the controlled drug release system showed a high ability to kill cancer cells and less damage to normal cells. These results indicated that PHHMs are promising for applications in various biomedical fields such as drug delivery system and oncotherapy. PMID:26952411

  8. Effect of hydroxyapatite-containing microspheres embedded into three-dimensional magnesium phosphate scaffolds on the controlled release of lysozyme and in vitro biodegradation.

    PubMed

    Lee, Jongman; Yun, Hui-Suk

    2014-01-01

    The functionality of porous three-dimensional (3D) magnesium phosphate (MgP) scaffold was investigated for the development of a novel protein delivery system and biomimetic bone tissue engineering scaffold. This enhancement can be achieved by incorporation of hydroxyapatite (HA)-containing polymeric microspheres (MSs) into a bulk MgP matrix, and a paste-extruding deposition (PED) system. In this work, the amount of MS and HA was precisely controlled when manufacturing MS-embedded MgP (MS/MgP) composite scaffolds. The main influence was researched in terms of in vitro lysozyme-release, in vitro biodegradation, mechanical properties, and in vitro calcification. The controlled release of lysozyme was indicated, while showing graded release patterns according to HA content. The composite scaffolds degraded gradually with MS content and degradation time. Due to the effect of HA inclusion, the higher HA-containing MS/MgP scaffolds could, not only delay the biodegradation process but also, compensate for the possible loss of mechanical properties. In this regard, it is reasonable to confirm the inverse relationship between biodegradation and corresponding compressive properties. In order to encourage bioactivity and osteoconductivity, the MS/MgP composite scaffolds were subjected to simulated body fluid treatment. Calcium deposition was, in turn, improved with increasing MS and HA content over time. This quantitative result was also proved using morphological and elemental analysis. In summary, a significant transformation of a monolithic MgP scaffold was directed toward a multifunctional bone tissue engineering scaffold equipped with controlled protein delivery, biodegradability, and bioactivity. PMID:25214782

  9. 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. PMID:26704551

  10. Preparation and bioevaluation of 166Ho labelled hydroxyapatite (HA) particles for radiosynovectomy.

    PubMed

    Unni, P R; Chaudhari, P R; Venkatesh, Meera; Ramamoorthy, N; Pillai, M R A

    2002-02-01

    The preparation of 166Ho labeled hydroxy apatite (HA) particles for radiosynovectomy applications is described in this paper. 166Ho was prepared by the irradiation of Ho2O3 at a flux of 1.8 x 10(13) neutrons/cm2/s for about 7 days. The irradiation resulted in the production of approximately 17 GBq of 166Ho activity at the end of six hours post end of bombardment and the corresponding specific activity was approximately 3-4 GBq/mg of Ho. The irradiated target was dissolved in 0.1 N HCl solution. Radionuclidic purity was ascertained by high resolution gamma ray spectrometry. HA particles were synthesized and characterized by X-ray diffractometry. Labeling studies were carried out with and without citric acid as a transchelating agent. Radiochemical yield and purity of the 166Ho-HA particles were ascertained by paper chromatography and by paper electrophoresis techniques. Labeling yield of >98% could be achieved at pH 7, with 40 mg of HA particles and 8.6 microg of Ho. 166Ho-HA particles prepared were stable for 72 h. Bio-evaluation of the 166Ho -HA particles were carried out by injecting approximately 74 MBq dose in 200 microL (approximately 8 mg of 166Ho-HA particles) directly into the arthritis induced knee joints as well as into the healthy knee joints of white New Zealand rabbits. Images of the injected joints of the animals recorded using a gamma camera at regular intervals showed good retention. Blood samples were collected from the animals and activity assayed in a scintillation detector. Experiments were also carried out under identical conditions in normal rabbits. In both the cases, it was observed that there was no significant extra articular leakage of the injected activity over the study period of 96 h post injection. PMID:11823125

  11. Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly-L-lactide (PLLA): Part I. Basic characteristics.

    PubMed

    Shikinami, Y; Okuno, M

    1999-05-01

    Compounds that had neither calcined nor sintered hydroxyapatite (u-HA) particles (particulate size 0.2-20 microns, averaging 3.0 microns, Ca/P = 1.69, and containing CO3(2-) uniformly distributed in a poly-L-lactide (PLLA, Mv: 400 KDa) matrix with a content of 20-50 wt% (with 10% increment) were reinforced into composites by a forging process, which was a unique compression molding, and were then machined on a lathe in order to produce practical radiopaque internal bone fixation devices having high mechanical strength which was maintained during bony union, total resorbability and bioactivity such as bone bonding capability and osteoconductivity. From the results of measurement of various mechanical properties, it was confirmed that the composites generally showed the highest mechanical strength among this type of reinforced bioceramic fibers or particles/bioresorbable polymer composite known to date. The bending strength (Sb) of about 270 MPa was far higher value than that for cortical bone, and the modulus (Eb) of 12 GPa was almost equivalent to that for cortical bone. In particular, the impact strength (Si) was extremely high at about two times the value (166 KJ/m2) of polycarbonate. The in vitro change in Sb, Mv (viscosity average molecular weight), Mw/Mn (molecular weight distribution) and crystallinity, and their relationship with each other was also examined by immersing samples in a phosphate buffer solution (PBS). An immediate decrease in the initial Mv could be found in composites with high u-HA contents (30-50 wt%), although a time-lag stage for degradation where the initial Mv hardly changes was apparent in cases of PLLA-only or in a composite with a low u-HA content (20 wt%). The Sb changed with corresponding decremental curves for the Mv and retained over 200 MPa for up to 24 weeks, the period of time necessary for full bony union, so that the composite satisfied initial mechanical strengths while maintaining them for as long as necessary for internal bone fixation devices. These results supported the idea that there is a difference in the degradation process such that PLLA alone required a period of time to achieve the possibility of hydrolysis into the inner side, whereas composites with high u-HA contents (30-50 wt%) immediately filled with water through to the inner side and were hydrolyzed homogeneously. Many hydroxyapatite crystals deposited and grew on the surface after 3-6 d and generously covered the surface with a fairly thick layer after 7 d of post-immersion in simulated body fluid (SBF) as evaluated by means of energy dispersive X-ray (EDX). This suggested the ability of the radiopaque composites to bond to bone. Since the composites were dense and had ultra-high strength, and the processability was so excellent, many kinds of fine and accurate screws, pins, plates, and other internal bone fixation devices for orthopedic, oral and maxillofacial, craniofacial, and plastic and reconstructive surgeries could be produced by machining treatment. These devices have potential applications for clinical use following the assessment of adaptation during in vivo studies. PMID:10226712

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  14. 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

    2016-01-01

    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 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. PMID:26956660

  15. 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

  16. 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. PMID:22323239

  17. 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.

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

    PubMed Central

    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. PMID:24531621

  19. 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. PMID:27040220

  20. 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. PMID:26998866

  1. 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. PMID:26774574

  2. 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. PMID:26952484

  3. 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 effect and fewer adverse side effects than direct intraperitoneal injection of ADM. The ADM-PLGA-NHAC developed in this study exhibited excellent extended-release drug properties, bone repairing and antineoplastic efficacy, which make it a promising osteoconductivity material with the capability to inhibit osteosarcoma. PMID:26975746

  4. 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

  5. Preparation, evaluation, and first clinical use of 177Lu-labeled hydroxyapatite (HA) particles in the treatment of rheumatoid arthritis: utility of cold kits for convenient dose formulation at hospital radiopharmacy.

    PubMed

    Chakraborty, Sudipta; Vimalnath, K V; Rajeswari, A; Shinto, Ajit; Sarma, H D; Kamaleshwaran, K; Thirumalaisamy, P; Dash, Ashutosh

    2014-06-15

    While radiation synovectomy (RSV) constitutes a successful paradigm for the treatment of arthritis, a major cornerstone of its success resides in the selection of appropriate radiolabeled agent. Among the radionuclide used for RSV, the scope of using (177)Lu [T1/2  = 6.65 d, Eβ(max)  = 497 keV, Eγ  = 113 KeV (6.4%), 208 KeV (11%)] seemed to be attractive owing to its suitable decay characteristics, easy availability, and cost-effective production route. The present article describes a formulation of (177)Lu-labeled hydroxyapatite (HA) using ready-to-use kits of HA particles of 1-10 µm size range. The developed kits enable convenient one-step preparation of (177)Lu-HA (400 ± 30 MBq doses) in high radiochemical purity (>99%) and stability at hospital radiopharmacy. The preparation showed promising results in pre-clinical studies carried out in Wistar rats bearing arthritis in knee joints. In preliminary clinical investigation, significant improvement in the disease conditions was reported in 10 patients with rheumatoid arthritis of knee joints treated with 333 ± 46 MBq doses of (177)Lu-HA. The studies reveal that while (177)Lu labeled HA particles holds considerable promise as a cost-effective agent for RSV, the adopted strategy of using HA kits could be a potential step toward wider clinical utilization of radiolanthanide-labeled HA particles. PMID:24966157

  6. Scanning Small- and Wide-Angle X-ray Scattering Microscopy Selectively Probes HA Content in Gelatin/Hydroxyapatite Scaffolds for Osteochondral Defect Repair.

    PubMed

    Altamura, Davide; Pastore, Stella G; Raucci, Maria G; Siliqi, Dritan; De Pascalis, Fabio; Nacucchi, Michele; Ambrosio, Luigi; Giannini, Cinzia

    2016-04-01

    This study is aimed at investigating the structure of a scaffold made of bovine gelatin and hydroxyapatite for bone tissue engineering purposes. In particular, the detailed characterization of such a material has a great relevance because of its application in the healing process of the osteochondral defect that consists of a damage of cartilage and injury of the adjacent subchondral bone, significantly compromising millions of patient's quality of life. Two different techniques exploiting X-ray radiation, with table-top setups, are used: microtomography (micro-CT) and microdiffraction. Micro-CT characterizes the microstructure in the three dimensions at the micrometer scale spatial resolution, whereas microdiffraction provides combined structural/morphological information at the atomic and nanoscale, in two dimensional microscopy images with a hundred micrometer spatial resolution. The combination of these two techniques allowed an appropriate structural characterization for the purpose of validating the engineering approach used for the realization of the hydroxyapatite gradient across the scaffold, with properties close to the natural model. PMID:27020229

  7. Facile and controllable synthesis of hydroxyapatite/graphene hybrid materials with enhanced sensing performance towards ammonia.

    PubMed

    Zhang, Qing; Liu, Yong; Zhang, Ying; Li, Huixia; Tan, Yanni; Luo, Lanlan; Duan, Junhao; Li, Kaiyang; Banks, Craig E

    2015-08-01

    In this work, needle-like and micro-spherical agglomerates of nanocrystalline hydroxyapatite (HA) were successfully assembled on the surface of graphene sheets with the aid of dopamine having two roles, as a template and a reductant for graphite oxide during the process of self-polymerization. The crystalline structure and micromorphology of HA can be conveniently regulated by controlling the mineralization route either with a precipitation (cHA/GR) or biomimetic methodology (bHA/GR). Both the composites exhibit improvements of ∼150% and ∼250% in sensitivity towards the sensing of ammonia at room temperature, compared with that of bare graphene. The combination of the multi-adsorption capability of HA and the electric conductivity of graphene is proposed to be the major reason for the observed enhancements. Gas sensing tests demonstrated that the HA/GR composites exhibit excellent selectivity, high sensitivity and repeatable stability towards the analytical sensing of ammonia. PMID:26066071

  8. 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.

  9. In vitro osteogenesis of synovium mesenchymal cells induced by controlled release of alendronate and dexamethasone from a sintered microspherical scaffold.

    PubMed

    Wang, Yingjun; Shi, Xuetao; Ren, Li; Yao, Yongchang; Wang, Dong-An

    2010-01-01

    In vitro osteogenesis was successfully achieved with synovium-derived mesenchymal stem cells (SMSCs), which intrinsically have a strong chondrogenic tendency, by in situ release of alendronate (AL) and dexamethasone (Dex) from poly(lactic-co-glycolic acid) (PLGA)/hydroxyapatite (HA) sintered microspherical scaffold (PLGA/HA-SMS). Cumulative release profiles of AL and Dex from PLGA/HA-SMS and the influence on SMSCs osteogenic commitment were investigated. SMSCs seeded in Al-/Dex-loaded PLGA/HA-SMS (PLGA/HA-Com-SMS) exhibited significant osteogenic differentiation, as indicated by high yields of alkaline phosphatase (ALP) and bone calcification. In addition, mechanical properties (compressional) of PLGA/HA-Com-SMSs were also evaluated and approved. In conclusion, by promoting osteogenic commitment of SMSCs in vitro, this newly designed controlled-release system opens a new door to bone reparation and regeneration. PMID:20507717

  10. 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

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

    PubMed

    Calasans-Maia, Mônica Diuana; Melo, Bruno Raposo de; Alves, Adriana Terezinha Neves Novellino; Resende, Rodrigo Figueiredo de Brito; Louro, Rafael Seabra; Sartoretto, Suelen Cristina; Granjeiro, José Mauro; Alves, Gutemberg Gomes

    2015-12-01

    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

  12. Production and characterization of HA and SiHA coatings.

    PubMed

    Tang, Qian; Brooks, Roger; Rushton, Neil; Best, Serena

    2010-01-01

    Plasma sprayed hydroxyapatite (HA) coatings on metallic prostheses have been used clinically in dentistry and orthopedics since the mid 1980s. The coating properties are dependent on the spraying parameters. Since silicon-substituted hydroxyapatite (SiHA) has been shown to offer improved bioactivity over phase pure HA, SiHA coatings have the potential for enhanced performance in clinical application. In this study, phase pure HA and 0.8 wt% SiHA powders were synthesized with similar particle size distribution and morphology. The powders were plasma sprayed onto Ti-6Al-4V substrates at 37 kW and 40 kW plasma gun input power respectively. Four kinds of samples were prepared, HAC 37, HAC 40, SiHAC 37 and SiHAC 40. Materials characterization showed that the coatings were of relatively high phase purity. In vitro cell culture demonstrated that human osteoblast cells grew well on all samples, with the highest cell growth observed on SiHA coatings produced under the lower plasma gun input power. PMID:19672562

  13. Facilitating the mineralization of oligo(poly(ethylene glycol) fumarate) hydrogel by incorporation of hydroxyapatite nanoparticles.

    PubMed

    Nejadnik, M Reza; Mikos, Antonios G; Jansen, John A; Leeuwenburgh, Sander C G

    2012-05-01

    Exploring strategies to induce the mineralization of hydrogels is an important step toward the development of hydrogel-based materials for bone regeneration. In the current study, the effect of incorporating hydroxyapatite (HA) nanoparticles on the mineralization capacity of an inert poly(ethylene glycol) (PEG)-based hydrogel was investigated. HA nanoparticles were either directly loaded into oligo(poly(ethylene glycol) fumarate) (OPF) hydrogel or loaded into commonly used gelatin microsphere porogens that were subsequently integrated in the OPF matrix. Mineralization of composites after immersion of the samples in simulated body fluid up to 28 days was assessed. In contrast to the blank OPF hydrogel, the HA-containing constructs strongly mineralized such that the average rate of calcium uptake by the material was enhanced by orders of magnitude. The mineral formed was observed to be apatitic and needle shaped. The presented method allows modification of inert PEG-based hydrogels into bioactive biomaterials for applications in bone regeneration. PMID:22374694

  14. Robotic deposition of model hydroxyapatite scaffolds with multiple architectures and multiscale porosity for bone tissue engineering.

    PubMed

    Dellinger, Jennifer G; Cesarano, Joseph; Jamison, Russell D

    2007-08-01

    Model hydroxyapatite (HA) scaffolds with porosities spanning multiple length scales were fabricated by robocasting, a solid freeform fabrication technique based on the robotic deposition of colloidal pastes. Scaffolds of various architectures including periodic, radial, and superlattice structures were constructed. Macropores (100-600 microm) were designed by controlling the arrangement and spacing between rods of HA. Micropores (1-30 microm) and submicron pores (less than 1 microm) were produced within the rods by including polymer microsphere porogens in the HA pastes and by controlling the sintering of the scaffolds. These model scaffolds may be used to systematically study the effects of scaffold porosity on bone ingrowth processes both in vitro and in vivo. PMID:17295231

  15. In-vitro osteogenesis of synovium stem cells induced by controlled release of bisphosphate additives from microspherical mesoporous silica composite.

    PubMed

    Shi, Xuetao; Wang, Yingjun; Varshney, Rohan R; Ren, Li; Zhang, Feng; Wang, Dong-An

    2009-08-01

    In this study, in-vitro osteogenesis was successfully induced in the highly chondrogenic synovium mesenchymal stem cells (SMSCs) by controlled release of a nitrogenous bisphosphonate additive--alendronate (AL) from a mesoporous silica (MS)-hydroxyapatite (HA) composite that was mediated in poly(lactic-co-glycolic acid) (PLGA) microspheres. This microspherical based controlled release system is constructed with three levels of degradable structures: (1) the AL drug was first hybridized with HA nanoparticles; (2) the HA-AL complexes were filled into the mesopores of MS particles by self-assembly in situ; and (3) the HA-AL-laden MS constructs (MSH-AL) were built in the bulk of PLGA microspheres. In comparison with any mono-component construct, the superiority of this multi-component system comes from two aspects of functionalities: (1) significantly greater loading capacity of the extremely hydrophilic drug-AL; and (2) better controlled profile of AL release. Based on this newly developed PLGA/MSH-AL releasing system, as recipients the SMSCs, which usually exhibit exclusively high chondrogenesis, demonstrated a strong osteogenic commitment. The results were verified by alkaline phosphatase (ALP) activity assay, calcium secretion assay, real time PCR and immunohistochemistry analysis. Considering the renewable source and high proliferative profile of SMSCs, the achievement of engineered SMSC osteogenesis with this PLGA/MSH-AL controlled release system would open a new door to major bony reparation and regeneration. PMID:19443027

  16. Nanoscale Adhesion Forces between Enamel Pellicle Proteins and Hydroxyapatite

    PubMed Central

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

    2014-01-01

    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. PMID:24591293

  17. 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 ?m in size, and struts ? 3-100 ?m 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. PMID:25644451

  18. Osteogenic effect of controlled released rhBMP-2 in 3D printed porous hydroxyapatite scaffold.

    PubMed

    Wang, Hai; Wu, Gui; Zhang, Jing; Zhou, Kui; Yin, Bo; Su, Xinlin; Qiu, Guixing; Yang, Guang; Zhang, Xianglin; Zhou, Gang; Wu, Zhihong

    2016-05-01

    Recently, 3D printing as effective technology has been highlighted in the biomedical field. Previously, a porous hydroxyapatite (HA) scaffold with the biocompatibility and osteoconductivity has been developed by this method. However, its osteoinductivity is limited. The main purpose of this study was to improve it by the introduction of recombinant human bone morphogenetic protein-2 (rhBMP-2). This scaffold was developed by coating rhBMP-2-delivery microspheres with collagen. These synthesized scaffolds were characterized by Scanning Electron Microscopy (SEM), a delivery test in vitro, cell culture, and the experiments in vivo by a Micro-computed tomography (μCT) scan and histological evaluation of VanGieson staining. SEM results indicated the surface of scaffolds were more fit for the adhesion of hMSCs to coat collagen/rhBMP-2 microspheres. Biphasic release of rhBMP-2 could continue for more than 21 days, and keep its osteoinductivity to induce osteogenic differentiation of hMSCs in vitro. In addition, the experiments in vivo showed that the scaffold had a good bone regeneration capacity. These findings demonstrate that the HA/Collagen/Chitosan Microspheres system can simultaneously achieve localized long-term controlled release of rhBMP-2 and bone regeneration, which provides a promising route for improving the treatment of bone defects. PMID:26896655

  19. 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.

  20. Microsphere-based selective laser sintering for building macroporous bone scaffolds with controlled microstructure and excellent biocompatibility.

    PubMed

    Du, Yingying; Liu, Haoming; Shuang, Jiaqi; Wang, Jianglin; Ma, Jun; Zhang, Shengmin

    2015-11-01

    Fabrication of bulk biomaterials with controlled structures and excellent properties is increasingly important in tissue engineering, but remains a major challenge in the current stage. Herein we used selective laser sintering (SLS) to construct a series of three-dimensional (3D) bone scaffolds with uniform multi-scaled porosity, moderate mechanical properties as well as good biocompatibility. As starting architectural units for SLS, the pure microspheres of polycaprolactone (PCL) and the composite microspheres of PCL and hydroxyapatite (HA) were firstly synthesized via a modified solvent evaporation method, respectively. Our findings showed that the as-prepared microspheres exhibited the uniform size and monodispersity. Moreover, the microsphere-based 3D scaffolds generated by SLS technique showed a multi-scaled porous structure, and adequate mechanical features. Both in vitro and in vivo evaluations further demonstrated that the resultant SLS-derived scaffolds can not only manipulate multiple stem cell behaviors including promoting cell adhesion, supporting cell proliferation and inducing cell differentiation in vitro, but also showed an excellent histocompatibility and induced the vascularization of newly formed tissue in vivo. Consequently, our current study suggests a feasible and effective protocol for fabricating new biomimetic bone biomaterials via SLS technique, also paves a new way for other bulk biomaterials. PMID:26241919

  1. 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. PMID:17486301

  2. Hydroxyapatite in Physiological Environment

    NASA Astrophysics Data System (ADS)

    Slepko, Alexander; Demkov, Alexander A.

    2011-03-01

    A carbonated form of hydroxyapatite (HA) [ Ca 10 (PO4)6 (OH)2 ] is one of the most abundant materials in mammal bone. It crystallizes within the spaces between tropocollagen protein chains in an aqueous solution and strengthens the bone tissue. An emerging application of synthetic HA is bone repair and replacement. Bulk electronic and chemical properties of HA were studied theoretically recently. However, the absorption of H2 O molecules and amino acids of the tropocollagen chains at HA surfaces remains an area of active research. Using density functional theory we analyze the electronic properties and surface energetics of HA for different orientations and terminations and generate a theoretical surface phase diagram of HA. The reactivity of these surface models is analyzed using the frontier orbital approach. We find two dominant surfaces which are most stable over the widest chemical range. However, we expect them to show little surface reactivity. Using a HA slab with a highly reactive surface we build atomistic models of HA covered with up to one monolayer of water and analyze interactions between this surface and the water molecules.

  3. 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.

  4. 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.

  5. 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.

  6. Dissolution studies of hydroxyapatite and glass-reinforced hydroxyapatite ceramics

    SciTech Connect

    Queiroz, A.C.; Santos, J.D.; Monteiro, F.J.; Prado da Silva, M.H

    2003-03-15

    In the continuous agitation assays, glass-reinforced hydroxyapatite (GR-HA) was shown to form a calcium phosphate (CaP) layer, but hydroxyapatite (HA) only formed dispersed precipitates. The formation of this layer was first detected on the GR-HA with a 7.5% glass addition (7.5 GR-HA) after only 3 days of immersion in simulated body fluid (SBF). The time required for layer formation decreased as the amount of glass added to the HA increased. The dissolution rate of the materials followed a similar pattern, i.e. the dissolution rate for GR-HA was higher than for HA, and increased with the addition of glass. The immersion of 7.5 GR-HA in water showed almost linear dissolution kinetics over the immersion periods (3, 7, 15, 30 and 60 days). The concentration of calcium ions in solution and the scanning electron microscopy (SEM) analysis of the 7.5 GR-HA specimens immersed in water and in SBF revealed a clear competition between the material dissolution and the precipitation of a CaP phase. Fourier transformed infrared spectroscopy with alternated total reflectance (FTIR-ATR) analysis indicated that the CaP phase that formed during longer immersion times (30 and 60 days) could be a carbonate-substituted CaP precipitate. As expected from previous work, the GR-HA behavior in terms of its in vitro bioactivity is higher than HA because a homogeneous CaP layer is formed and the precipitation occurs faster. From the dissolution test and in accordance with the chemical composition of the samples, GR-HA was more soluble than HA.

  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. Cementless hydroxyapatite coated hip prostheses.

    PubMed

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

    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

  9. In vivo assessment of hydroxyapatite and silicate-substituted hydroxyapatite granules using an ovine defect model.

    PubMed

    Patel, N; Brooks, R A; Clarke, M T; Lee, P M T; Rushton, N; Gibson, I R; Best, S M; Bonfield, W

    2005-05-01

    Phase pure hydroxyapatite (HA) and two silicate-substituted hydroxyapatites (0.8 and 1.5 wt% Si, or 2.6 and 4.9 wt% SiO4) were prepared by aqueous precipitation methods. The filter-cakes of HA and silicate-substituted hydroxyapatite (SiHA) compositions were processed into granules 1.0-2.0 mm in diameter and sintered at 1200 degrees C for 2 h. The sintered granules underwent full structural characterisation, prior to assessment in an ovine defect model by implantation for a period of 6 and 12 weeks. The results indicate that HA and SiHA implants were well accepted by the host tissue, with no evidence of inflammation. New bone formation was observed directly on the surfaces and in the spaces between the granular implants. Quantitative histomorphometry as determined by the percentage of bone ingrowth and bone coverage for both SiHA implant compositions was significantly greater than that for phase pure HA. These findings indicate that the in vivo bioactivity of hydroxyapatite was significantly improved by the incorporation of silicate ions into the HA structure, making SiHA ceramics attractive alternatives to conventional HA materials for use as bone graft substitute ceramics. PMID:15875253

  10. 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.

  11. 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. PMID:11543409

  12. 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.

  13. Physical and chemical aspects of a new porous hydroxyapatite.

    PubMed

    Martinetti, R; Dolcini, L; Mangano, C

    2005-02-01

    The new engineered porous hydroxyapatite (EP-HA) described in this paper seems to be suitable as a bone substitute. Its physico-chemical characteristics and morphology are similar to those of natural bone. Study of its histological behaviour in humans revealed bone formation within and around the porous hydroxyapatite that is markedly resorbed. PMID:15692812

  14. Cements from nanocrystalline hydroxyapatite.

    PubMed

    Barralet, J E; Lilley, K J; Grover, L M; Farrar, D F; Ansell, C; Gbureck, U

    2004-04-01

    Calcium phosphate cements are used as bone substitute materials because they may be moulded to fill a void or defect in bone and are osteoconductive. Although apatite cements are stronger than brushite cements, they are potentially less resorbable in vivo. Brushite cements are three-component systems whereby phosphate ions and water react with a soluble calcium phosphate to form brushite (CaHPO4 x 2H2O). Previously reported brushite cement formulations set following the mixture of a calcium phosphate, such as beta-tricalcium phosphate (beta-TCP), with an acidic component such as H3PO4 or monocalcium phosphate monohydrate (MCPM). Due to its low solubility, hydroxyapatite (HA) is yet to be reported as a reactive component in calcium phosphate cement systems. Here we report a new cement system setting to form a matrix consisting predominantly of brushite following the mixture of phosphoric acid with nanocrystalline HA. As a result of the relative ease with which ionic substitutions may be made in apatite this route may offer a novel way to control cement composition or setting characteristics. Since kinetic solubility is dependent on particle size and precipitation temperature is known to affect precipitated HA crystal size, the phase composition and mechanical properties of cements made from HA precipitated at temperatures between 4 and 60 degrees C were investigated. PMID:15332608

  15. 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.

  16. 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.

  17. Biodegradable composites with aligned hydroxyapatite nanoneedles.

    PubMed

    Sun, Shih-Po; Wei, Mei; Olson, James R; Shaw, Montgomery T

    2012-10-01

    We prepared an anisotropic bone graft composite to mimic the hierarchical structure of the natural bone in which aligned hydroxyapatite (HA) nanocrystals deposit along collagen fibers. To approach the modulus and strength of the bone, we incorporated synthesized HA nanoneedles and melt drawn poly(L-lactic acid) fibers in our composite as reinforcing components. Their preferred orientation was induced via a modified pultrusion process. The HA orientation distribution was examined using wide angle X-ray diffraction. Micromechanical Halpin-Tsai model predictions considering the amount, shape, and orientation distribution of HA were compared, favorably, with the experimental observations. PMID:22821763

  18. 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.

  19. Fabrication and characterization of needle-like nano-HA and HA/MWNT composites.

    PubMed

    Meng, Y H; Tang, Chak Yin; Tsui, Chi Pong; Chen, Da Zhu

    2008-01-01

    Hydroxyapatite (HA) ceramic has been used in tissue engineering and orthopedics for its good biocompatibility and osteoconductivity. However, its clinical applications are usually limited by the low strength and brittleness. The objective of this research was to develop a new kind of HA composites in which multi-wall carbon nanotubes (MWNTs) were introduced to the HA ceramic matrix to improve the mechanical properties of the resulting composites. A simple chemical wet method was applied to synthesize the HA ceramic particles with the aid of surfactant and ultrasonication technique at normal atmospheric pressure. The morphology and microstructure of the synthesized HA were characterized by XRD and TEM as a function of treatment time. The results showed that the synthesized HA particles are needle-like with a length of 80-160 nm along the (211) direction and an aspect ratio of 5-15. MWNTs were treated with a mixture of nitric acid and sulfuric acid. The HA/MWNT composites were prepared by solution blending. The composites were sintered using a hot-press method. The mechanical properties of the HA/MWNT composites with different volume percentages of MWNTs were examined. The fracture toughness and flexural strength were improved by 50% and 28% separately when the volume percentage of MWNTs reached 7%. PMID:17577639

  20. 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.

  1. 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 technique appears to be the reaction of the encapsulating material--whether soda glass, steel, or fused silica--to the HA coating. More extensive testing will necessary to determine the ideal conditions for the HIP technique, as efforts on this technique were discontinued in order to concentrate on the HIP technique, as efforts on this technique were discontinued in order to concentrate on the optimization of the sputter-coating technique so that coated implants for an animal study could be produced on schedule. Based on the results of this study, sputter coating appears to be the method of choice for forming a dense, adherent coating of HA onto a metal substrate.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3382133

  2. 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...

  3. 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...

  4. 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.

  5. 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. PMID:26726671

  6. 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.

  7. 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 staining might indicate either extracellular matrix (ECM) in the rods or dye bound to the degrading scaffold. Although the presence of microporous topography alone did not influence bone healing in vivo, micropores were shown to provide tailorability of scaffold mechanical properties, provide a location for the storage and controlled release of a growth factor, and provide a location for bone integration inside the scaffold rods.

  8. A prospective randomized study comparing electrochemically deposited hydroxyapatite and plasma-sprayed hydroxyapatite on titanium stems

    PubMed Central

    2011-01-01

    Background and purpose Plasma-sprayed hydroxyapatite (HA) is a successful coating for fixation of uncemented femoral stems. There may be alternative coatings with advantages in bone remodeling and transport of bone-active substances. We investigated whether an electrochemically deposited hydroxyapatite, Bonemaster (BM), might be a safe alternative in total hip arthroplasty. Our hypothesis was that the new coating would not be inferior to the conventional one. Patients and methods 50 patients (55 hips) were included. The stem was tapered and porous-coated proximally. On top of the porous coating was either HA or BM. Patients were evaluated postoperatively and after 3, 6, 12, and 24 months to measure fixation by radiostereometric analysis (RSA), bone mineral density by dual-energy X-ray absorptiometry (DXA), and conventional radiography. Clinical evaluation was performed with Harris hip score and Oxford hip score, both preoperatively and after 2 years. Results After 2 years, the stems had subsided 0.25 (HA) and 0.28 (BM) mm and there were no statistically significant differences between the groups in any direction, regarding both migration and rotation. The BM group retained significantly more bone than the HA group in Gruen zone 1 during the first 2 years. The Harris and Oxford hip scores were similar in both groups. Interpretation Electrochemically deposited hydroxyapatite on an uncemented stem does not appear to be inferior to plasma-sprayed HA regarding clinical and radiological results, bone remodeling, and micromotion after 2 years follow-up. PMID:21189109

  9. Characterization of New PEEK/HA Composites with 3D HA Network Fabricated by Extrusion Freeforming.

    PubMed

    Vaezi, Mohammad; Black, Cameron; Gibbs, David M R; Oreffo, Richard O C; Brady, Mark; Moshrefi-Torbati, Mohamed; Yang, Shoufeng

    2016-01-01

    Addition of bioactive materials such as calcium phosphates or Bioglass, and incorporation of porosity into polyetheretherketone (PEEK) has been identified as an effective approach to improve bone-implant interfaces and osseointegration of PEEK-based devices. In this paper, a novel production technique based on the extrusion freeforming method is proposed that yields a bioactive PEEK/hydroxyapatite (PEEK/HA) composite with a unique configuration in which the bioactive phase (i.e., HA) distribution is computer-controlled within a PEEK matrix. The 100% interconnectivity of the HA network in the biocomposite confers an advantage over alternative forms of other microstructural configurations. Moreover, the technique can be employed to produce porous PEEK structures with controlled pore size and distribution, facilitating greater cellular infiltration and biological integration of PEEK composites within patient tissue. The results of unconfined, uniaxial compressive tests on these new PEEK/HA biocomposites with 40% HA under both static and cyclic mode were promising, showing the composites possess yield and compressive strength within the range of human cortical bone suitable for load bearing applications. In addition, preliminary evidence supporting initial biological safety of the new technique developed is demonstrated in this paper. Sufficient cell attachment, sustained viability in contact with the sample over a seven-day period, evidence of cell bridging and matrix deposition all confirmed excellent biocompatibility. PMID:27240326

  10. Surface-induced changes in the conformation and glucan production of glucosyltransferase adsorbed on saliva-coated hydroxyapatite.

    PubMed

    Fears, Kenan P; Gonzalez-Begne, Mireya; Love, Corey T; Day, Delbert E; Koo, Hyun

    2015-04-28

    Glucosyltransferases (Gtfs) from S. mutans play critical roles in the development of virulent oral biofilms associated with dental caries disease. Gtfs adsorbed to the tooth surface produce glucans that promote local microbial colonization and provide an insoluble exopolysaccharides (EPS) matrix that facilitates biofilm initiation. Moreover, agents that inhibit the enzymatic activity of Gtfs in solution often have reduced or no effects on surface-adsorbed Gtfs. This study elucidated the mechanisms responsible for the differences in functionality that GtfB exhibits in solution vs surface-adsorbed. Upon adsorption to planar fused-quartz substrates, GtfB displayed a 37% loss of helices and 36% increase of β-sheets, as determined by circular dichroism (CD) spectroscopy, and surface-induced conformational changes were more severe on substrates modified with CH3- and NH2-terminated self-assembled monolayers. GtfB also underwent substantial conformation changes when adsorbing to hydroxyapatite (HA) microspheres, likely due to electrostatic interactions between negatively charged GtfB and positively charged HA crystal faces. Conformational changes were lessened when HA surfaces were coated with saliva (sHA) prior to GtfB adsorption. Furthermore, GtfB remained highly active on sHA, as determined by in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, producing glucans that were structurally different than GtfB in solution and known to increase the accumulation and virulence of biofilms. Our data provide the first insight into the structural underpinnings governing Gtf conformation and enzymatic function that occur on tooth surfaces in vivo, which may lead to designing potent new inhibitors and improved strategies to combat the formation of pathogenic oral biofilms. PMID:25867796

  11. 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.

  12. Effect of protein on the dissolution of HA coatings.

    PubMed

    Bender, S A; Bumgardner, J D; Roach; Bessho, K; Ong, J L

    2000-02-01

    The dissolution behavior of hydroxyapatite (HA) in the presence and absence of protein needs to be investigated in order to fully understand the initial cellular response to HA surfaces. In this study, HA coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (FTIR) prior to protein study. Fibronectin and albumin adsorption study were also performed. Calcium and phosphorus released in the presence and absence of albumin were measured. pH of the solution was measured daily. From the materials characterization, it was observed that the coatings exhibit a HA-type structure, with traces of sodium on the surface. FTIR indicated the possible presence of carbonates on the coatings. From the adsorption study, the amount of albumin adsorbed (0.052+/-0.005 microg/mm2) was statistically higher than the amount of fibronectin adsorbed on HA surfaces (0.035+/-0.002 microg/mm2). Flame atomic absorption indicated a significantly higher calcium ions released initially for HA coatings incubated with proteins as compared to coatings in the absence of proteins. However, after 7 days incubation, no significant difference in calcium ions release was observed between the HA coatings in the presence and absence of proteins. Phosphorus dissolution on HA coatings was not significantly affected by the presence of proteins. Thus, it was suggested from this study that the initial dissolution properties of calcium ions from HA coatings was dependent on the media. PMID:10646947

  13. Effects of degradation and porosity on the load bearing properties of model hydroxyapatite bone scaffolds.

    PubMed

    Dellinger, Jennifer G; Wojtowicz, Abigail M; Jamison, Russell D

    2006-06-01

    Degradation of three types of model hydroxyapatite (HA) scaffolds was studied after in vitro degradation in a sodium acetate buffer (pH 4). Degradation was evaluated using compression testing, scanning electron microscopy (SEM), inductively coupled plasma (ICP) analysis, and weight measurements. Scaffolds were fabricated with a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes. Scaffolds had a macrostructure resembling a lattice of rods. Scaffolds contained either macropores (270 or 680 microm in the x-y direction and 280 microm in the z-direction) and micropores (1-30-microm pores and pores <1 microm) or only macropores pores (270 microm in the x-y direction and 280 microm in the z-direction). A computer-aided design (CAD) program controlled the size and distribution of macropores; micropores were created by polymethylmethacrylate (PMMA) microsphere porogens (1-30-microm pore diameter) and controlled sintering (pores <1 microm). Percent weight loss of the scaffolds and calcium and phosphorus ion concentrations in solution increased as the degradation period increased for all scaffold types. After degradation, compressive strength and compressive modulus decreased significantly for those scaffolds with microporosity. For scaffolds without microporosity, the changes in strength and modulus after degradation were not statistically significant. The compressive strength of scaffolds without microporosity was significantly greater than the scaffolds with microporosity. PMID:16498598

  14. Effects of degradation and porosity on the load bearing properties of model hydroxyapatite bone scaffolds.

    SciTech Connect

    Dellinger, Jennifer Gwynne; Cesarano, Joseph, III; Jamison, Russell D.; Wojtowicz, Abigail M.

    2005-06-01

    Degradation of three types of model hydroxyapatite (HA) scaffolds was studied after in vitro degradation in a sodium acetate buffer (pH 4). Degradation was evaluated using compression testing, scanning electron microscopy (SEM), inductively coupled plasma (ICP) analysis, and weight measurements. Scaffolds were fabricated with a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes. Scaffolds had a macrostructure resembling a lattice of rods. Scaffolds contained either macropores (270 or 680 m in the x-y direction and 280 m in the z-direction) and micropores (1-30-m pores and pores <1 m) or only macropores pores (270 m in the x-y direction and 280 m in the z-direction). A computer-aided design (CAD) program controlled the size and distribution of macropores; micropores were created by polymethylmethacrylate (PMMA) microsphere porogens (1-30-m pore diameter) and controlled sintering (pores <1 m). Percent weight loss of the scaffolds and calcium and phosphorus ion concentrations in solution increased as the degradation period increased for all scaffold types. After degradation, compressive strength and compressive modulus decreased significantly for those scaffolds with microporosity. For scaffolds without microporosity, the changes in strength and modulus after degradation were not statistically significant. The compressive strength of scaffolds without microporosity was significantly greater than the scaffolds with microporosity.

  15. Biodegradable magnesium-hydroxyapatite metal matrix composites.

    PubMed

    Witte, Frank; Feyerabend, Frank; Maier, Petra; Fischer, Jens; Störmer, Michael; Blawert, Carsten; Dietzel, Wolfgang; Hort, Norbert

    2007-04-01

    Recent studies indicate that there is a high demand to design magnesium alloys with adjustable corrosion rates and suitable mechanical properties. An approach to this challenge might be the application of metal matrix composite (MMC) based on magnesium alloys. In this study, a MMC made of magnesium alloy AZ91D as a matrix and hydroxyapatite (HA) particles as reinforcements have been investigated in vitro for mechanical, corrosive and cytocompatible properties. The mechanical properties of the MMC-HA were adjustable by the choice of HA particle size and distribution. Corrosion tests revealed that HA particles stabilised the corrosion rate and exhibited more uniform corrosion attack in artificial sea water and cell solutions. The phase identification showed that all samples contained hcp-Mg, Mg(17)Al(12), and HA before and after immersion. After immersion in artificial sea water CaCO3 was found on MMC-HA surfaces, while no formation of CaCO3 was found after immersion in cell solutions with and without proteins. Co-cultivation of MMC-HA with human bone derived cells (HBDC), cells of an osteoblasts lineage (MG-63) and cells of a macrophage lineage (RAW264.7) revealed that RAW264.7, MG-63 and HBDC adhere, proliferate and survive on the corroding surfaces of MMC-HA. In summary, biodegradable MMC-HA are cytocompatible biomaterials with adjustable mechanical and corrosive properties. PMID:17276507

  16. Adhesion behaviors of Escherichia coli on hydroxyapatite.

    PubMed

    Kamitakahara, Masanobu; Takahashi, Shohei; Yokoi, Taishi; Inoue, Chihiro; Ioku, Koji

    2016-04-01

    Optimum design of support materials for microorganisms is required for the construction of bioreactors. However, the effects of support materials on microorganisms are still unclear. In this study, we investigated the adhesion behavior of Escherichia coli (E. coli) on hydroxyapatite (HA), polyurethane (PU), poly(vinyl chloride) (PVC), and carbon (Carbon) to obtain basic knowledge for the design of support materials. The total metabolic activity and number of E. coli adhering on the samples followed the order of HA≈Carbon>PVC>PU. On the other hand, the water contact angle of the pellet surfaces followed the order of HAHA surface might be one of the suitable characters for the adhesion of E. coli. The results implied that HA has a potential as a support material for microorganisms used in bioreactors. PMID:26838837

  17. 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. PMID:15875256

  18. 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.

  19. 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.

  20. Effect of Thickness of HA-Coating on Microporous Silk Scaffolds Using Alternate Soaking Technology

    PubMed Central

    Zhu, Rui; Xue, Yingsen; Hao, Zhangying; Xie, Zhenghong; Fan, Xiangli; Fan, Hongbin

    2014-01-01

    Hydroxyapatite (HA) can be coated on various materials surface and has the function of osteogenicity. Microporous silk scaffold has excellent biocompatibility. In this study, alternate soaking technology was used to coat HA on microporous silk scaffolds. However, the cell proliferation was found to decrease with the increasing thickness (cycles of soaking) of HA-coating. This study aims to determine the best thickness (cycles of soaking) of HA-coating on microporous silk scaffolds. The SEM observation showed that group with one cycle of alternate soaking (1C-HA) has the most optimal porosity like non-HA-modified microporous silk scaffolds. The proliferation of osteoblasts has no significant difference between noncoated HA (N-HA) and 1C-HA groups, which are both significantly higher than those in two cycles of soaking (2C-HA) and three cycles of soaking (3C-HA) groups. The transcription levels of specific genes (runx2 and osteonectin) in osteoblasts of 1C-HA group were significantly higher than those of N-HA group. Moreover, the levels showed no significant difference among 1C-HA, 2C-HA, and 3C-HA groups. In conclusion, microporous silk scaffold with 1 cycle of HA-coating can combine the biocompatibility of silk and osteogenicity of HA. PMID:25093176

  1. Electrospinning of Hyaluronic acid (HA) and HA/Gelatin Blends

    NASA Astrophysics Data System (ADS)

    He, Aihua; Li, Junxing; Han, Charles; Fang, Dufei; Hsiao, Benjamin; Chu, Benjamin

    2007-03-01

    It was found that the processability of HA solution with high viscosity had been improved greatly by using a DMF-water solvent mixture or/and by adding gelatin(GE) into the HA solution. Nano-fibrous membranes with different average fiber diameters and different HA/GE compositions could be obtained. Measurements on viscosity indicated that the HA solution in DMF-water mixed solvent still showed high viscosity. The decrease in surface tension contributed to the fiber formation of HA and HA/GE by electrospinning. Therefore, this study not only provided a novel and simpler way to electrospin the natural polyanion HA solution, but also provided the fundamental physical insight and solution to this spinning difficulty. The HA-GE nanofibrous membranes at different HA/GE compositions are expected to be useful in the biomedical field as novel scaffolds for many applications.

  2. Characterization of processed tooth hydroxyapatite for potential biomedical implant applications.

    PubMed

    Oktar, F N; Kesenci, K; Pişkin, E

    1999-07-01

    In this study hydroxyapatite (HA) (100-150 microns) derived from freshly-extracted human teeth in laboratory conditions was investigated. Scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDXS), wet chemical, ion chromatographic peak method (ICP), atomic absorption, x-ray diffraction and infra-red (IR) were performed separately for HA obtained from dentine and enamel. This naturally derived HA did not differ from synthetic ones. Its production was simple when compared with other methods. Processed tooth HA could safely be used in animal subjects prior to human studies as a graft material after biocompatibility studies fully conducted. PMID:10427420

  3. Zinc and Carbonate Co-Substituted Nano-Hydroxyapatite

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    Synthesis of Zn or CO32- substituted nano-hydroxyapatite (HA) and its physico-chemical properties have been well documented. However, the effects of the simultaneous substitution of Zn and CO32- in nano-HA have not been reported. In the present study, Zn and CO32- substitutions in nano HA independently and concurrently have been done by wet precipitation method and characterized by XRD and FT-IR for its phase purity and chemical homogeneity. Further modulations of the bioactivity and thermal stability of HA due to the substitutions have been studied.

  4. Synthesis, structural properties and thermal stability of Mn-doped hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Paluszkiewicz, Czes?awa; ?lsarczyk, Anna; Pijocha, Dawid; Sitarz, Maciej; Bu?ko, Miros?aw; Zima, Aneta; Chr?cicka, Anna; Lewandowska-Szumie?, Ma?gorzata

    2010-07-01

    Hydroxyapatite (HA) - Ca 10(PO 4) 6(OH) 2 is a basic inorganic model component of hard biological tissues, such as bones and teeth. The significant property of HA is its ability to exchange Ca 2+ ions, which influences crystallinity, physico-chemical and biological properties of modified hydroxyapatite materials. In this work, FTIR, Raman spectroscopy, XRD, SEM and EDS techniques were used to determine thermal stability, chemical and phase composition of Mn containing hydroxyapatite (MnHA). Described methods confirmed thermal decomposition and phase transformation of MnHA to ?TCP, ?TCP and formation of Mn 3O 4 depending on sintering temperature and manganese content. In vitro biological evaluation of Mn-modified HA ceramics was also performed using human osteoblast cells.

  5. 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.

  6. 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). PMID:23421285

  7. 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)]. PMID:23902010

  8. 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.

  9. 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.

  10. Near net-shape fabrication of hydroxyapatite glass composites.

    PubMed

    Zhu, Qingshan; De With, Gijsbertus; Dortmans, Leonardus J M G; Feenstra, Frits

    2004-11-01

    Near net-shape fabrication of hydroxyapatite (HA) glass composites has been attempted by infiltrating a glass into porous HA performs. Main efforts were put to develop glasses that are chemically compatible with HA at elevated temperatures. After extensive investigations in the phosphate and borosilicate systems, glasses of (50-55)SiO2-(20-25)B203-(10-20)Li2O-(0-6)CaO (wt%) composition were successfully developed. The glass shows good chemical compatibility with HA at elevated temperatures. Dense HA/glass composites can be fabricated at 850-950 degress C by the melt infiltration process. Investigations demonstrated a good near net-shape capability of the process, where the linear shrinkage induced by the infiltration process is less than 0.1%. Preliminary mechanical tests showed that the fracture strength and toughness of the infiltrated HA/glass composite are comparable with dense HA. PMID:15880926

  11. HDPE-HA composites synthetized by in situ polymerization with different filler content

    NASA Astrophysics Data System (ADS)

    Hermán, V.; Karam, A.; Albano, C.; Romero, K.; González, G.

    2012-07-01

    In Situ ethylene polymerization was used to synthesize high density polyethylene - hydroxyapatite (HDPE-HA) composites, employing Cp2ZrCl2/MAO as catalytic system. A good dispersion of HA into the HDPE matrix was obtained when the following synthesis conditions were combined: high stirring velocities (2000 rpm), low quantities of solvent (100 mL), and 10 °C. Under these conditions different filler content was used to synthetized HDPE-HA composites. An interaction between HA and HDPE was obtained by FTIR. On the other hand, thermal analysis indicated that no significant differences were observed between HDPE and the composites.

  12. The Effect of Zirconia in Hydroxyapatite on Staphylococcus epidermidis Growth

    PubMed Central

    Siswomihardjo, Widowati; Sunarintyas, Siti; Tontowi, Alva Edy

    2012-01-01

    Synthetic hydroxyapatite (HA) has been widely used and developed as the material for bone substitute in medical applications. The addition of zirconia is needed to improve the strength of hydroxyapatite as the bone substitute. One of the drawbacks in the use of biomedical materials is the occurrence of biomaterial-centred infections. The recent method of limiting the presence of microorganism on biomaterials is by providing biomaterial-bound metal-containing compositions. In this case, S. epidermidis is the most common infectious organism in biomedical-centred infection. Objective. This study was designed to evaluate the effect of zirconia concentrations in hydroxyapatite on the growth of S. epidermidis. Methods and Materials. The subjects of this study were twenty hydroxyapatite discs, divided into four groups in which one was the control and the other three were the treatment groups. Zirconia powder with the concentrations of 20%, 30%, and 40% was added into the three different treatment groups. Scanning electron microscope analysis was performed according to the hydroxyapatite and hydroxyapatite-zirconia specimens. All discs were immersed into S. epidermidis culture for 24 hours and later on they were soaked into a medium of PBS. The cultured medium was spread on mannitol salt agar. After incubation for 24 hours at 37°C , the number of colonies was measured with colony counter. Data obtained were analyzed using the ANOVA followed by the pairwise comparison. Result. The statistical analysis showed that different concentrations of zirconia powder significantly influenced the number of S. epidermidis colony (P < 0.05) . Conclusion. The addition of zirconia into hydroxyapatite affected the growth of S. epidermidis. Hydroxyapatite with 20% zirconia proved to be an effective concentration to inhibit the growth of S. epidermidis colony. PMID:22919390

  13. Spherical porous hydroxyapatite granules containing composites of magnetic and hydroxyapatite nanoparticles for the hyperthermia treatment of bone tumor.

    PubMed

    Kamitakahara, Masanobu; Ohtoshi, Naohiro; Kawashita, Masakazu; Ioku, Koji

    2016-05-01

    Spherical porous granules of hydroxyapatite (HA) containing magnetic nanoparticles would be suitable for the hyperthermia treatment of bone tumor, because porous HA granules act as a scaffold for bone regeneration, and magnetic nanoparticles generate sufficient heat to kill tumor cells under an alternating magnetic field. Although magnetic nanoparticles are promising heat generators, their small size makes them difficult to support in porous HA ceramics. We prepared micrometer-sized composites of magnetic and HA nanoparticles, and then supported them in porous HA granules composed of rod-like particles. The spherical porous HA granules containing the composites of magnetic and HA nanoparticle were successfully prepared using a hydrothermal process without changing the crystalline phase and heat generation properties of the magnetic nanoparticles. The obtained granules generated sufficient heat for killing tumor cells under an alternating magnetic field (300 Oe at 100 kHz). The obtained granules are expected to be useful for the hyperthermia treatment of bone tumors. PMID:26984358

  14. 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

  15. 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.

  16. 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. PMID:24907766

  17. Biomedical potential of chitosan/HA and chitosan/β-1,3-glucan/HA biomaterials as scaffolds for bone regeneration--A comparative study.

    PubMed

    Przekora, Agata; Palka, Krzysztof; Ginalska, Grazyna

    2016-01-01

    The aim of this work was to compare biomedical potential of chitosan/hydroxyapatite (chit/HA) and novel chitosan/β-1,3-glucan/hydroxyapatite (chit/glu/HA) materials as scaffolds for bone regeneration via characterization of their biocompatibility, porosity, mechanical properties, and water uptake behaviour. Biocompatibility of the scaffolds was assessed in direct-contact with the materials using normal human foetal osteoblast cell line. Cytotoxicity and osteoblast proliferation rate were evaluated. Porosity was assessed using computed microtomography analysis and mechanical properties were determined by compression testing. Obtained results demonstrated that chit/HA scaffold possessed significantly better mechanical properties (compressive strength: 1.23 MPa, Young's modulus: 0.46 MPa) than chit/glu/HA material (compressive strength: 0.26 MPa, Young's modulus: 0.25 MPa). However, addition of bacterial β-1,3-glucan to the chit/HA scaffold improved its flexibility and porosity. Moreover, chit/glu/HA scaffold revealed significantly higher water uptake capability (52.6% after 24h of soaking) compared to the chit/HA (30.7%) and thus can serve as a very good drug delivery carrier. Chit/glu/HA scaffold was also more favourable to osteoblast survival (near 100% viability after 24-h culture), proliferation, and spreading compared to the chit/HA (63% viability). The chit/glu/HA possesses better biomedical potential than chit/HA scaffold. Nevertheless, poor mechanical properties of the chit/glu/HA limit its application to non-load bearing implantation area. PMID:26478384

  18. 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.

  19. Risedronate/zinc-hydroxyapatite based nanomedicine for osteoporosis.

    PubMed

    Khajuria, Deepak Kumar; Disha, Choudhary; Vasireddi, Ramakrishna; Razdan, Rema; Mahapatra, D Roy

    2016-06-01

    Targeting of superior osteogenic drugs to bone is an ideal approach for treatment of osteoporosis. Here, we investigated the potential of using risedronate/zinc-hydroxyapatite (ZnHA) nanoparticles based formulation in a rat model of experimental osteoporosis. Risedronate, a targeting moiety that has a strong affinity for bone, was loaded to ZnHA nanoparticles by adsorption method. Prepared risedronate/ZnHA drug formulation was characterized by field-emission scanning electron microscopy, X-ray diffraction analysis and fourier transform infrared spectroscopy. In vivo performance of the prepared risedronate/ZnHA nanoparticles was tested in an experimental model of postmenopausal osteoporosis. Therapy with risedronate/ZnHA drug formulation prevented increase in serum levels of bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase 5b better than risedronate/HA or risedronate. With respect to improvement in the mechanical strength of the femoral mid-shaft and correction of increase in urine calcium and creatinine levels, the therapy with risedronate/ZnHA drug formulation was more effective than risedronate/HA or risedronate therapy. Moreover, risedronate/ZnHA drug therapy preserved the cortical and trabecular bone microarchitecture better than risedronate/HA or risedronate therapy. Furthermore, risedronate/ZnHA drug formulation showed higher values of calcium/phosphorous ratio and zinc content. The results strongly implicate that risedronate/ZnHA drug formulation has a therapeutic advantage over risedronate or risedronate/HA therapy for the treatment of osteoporosis. PMID:27040198

  20. Citric Acid-based Hydroxyapatite Composite Scaffolds Enhance Calvarial Regeneration

    PubMed Central

    Sun, Dawei; Chen, Yuhui; Tran, Richard T.; Xu, Song; Xie, Denghui; Jia, Chunhong; Wang, Yuchen; Guo, Ying; Zhang, Zhongmin; Guo, Jinshan; Yang, Jian; Jin, Dadi; Bai, Xiaochun

    2014-01-01

    Citric acid-based polymer/hydroxyapatite composites (CABP-HAs) are a novel class of biomimetic composites that have recently attracted significant attention in tissue engineering. The objective of this study was to compare the efficacy of using two different CABP-HAs, poly (1,8-octanediol citrate)-click-HA (POC-Click-HA) and crosslinked urethane-doped polyester-HA (CUPE-HA) as an alternative to autologous tissue grafts in the repair of skeletal defects. CABP-HA disc-shaped scaffolds (65 wt.-% HA with 70% porosity) were used as bare implants without the addition of growth factors or cells to renovate 4 mm diameter rat calvarial defects (n = 72, n = 18 per group). Defects were either left empty (negative control group), or treated with CUPE-HA scaffolds, POC-Click-HA scaffolds, or autologous bone grafts (AB group). Radiological and histological data showed a significant enhancement of osteogenesis in defects treated with CUPE-HA scaffolds when compared to POC-Click-HA scaffolds. Both, POC-Click-HA and CUPE-HA scaffolds, resulted in enhanced bone mineral density, trabecular thickness, and angiogenesis when compared to the control groups at 1, 3, and 6 months post-trauma. These results show the potential of CABP-HA bare implants as biocompatible, osteogenic, and off-shelf-available options in the repair of orthopedic defects. PMID:25372769

  1. Hydroxyapatite synthesis using EDTA

    PubMed Central

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

    2013-01-01

    Bone comprises structure of body and is 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 time consuming make the production difficult. In this study we synthesized the hydroxyapatite with Ethyenediamine tetraacetic acid. Freeze Dried Bone Allograft(Hans Biomed) was used to be a control group. Synthesized hydroxyapatite was a rod shape, white powdery type substance with 2 ~ 5 μm length and 0.5 ~ 1 μm width. X-ray diffraction showed the highest sharp peak at 32° and high peaks at 25.8°, 39.8°, 46.8°, 49.5°, and 64.0° indicating a similar substance to the freeze Dried Bone Allograft. 3 days after the cell growth of synthesized hydroxyapatite showed 1.5 fold more than the Bone Allograft. Cellular and media alkaline phosphate activity increased similar to the bone alloagraft. 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 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. PMID:23714942

  2. 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. PMID:23714942

  3. Comparing microspheres with different internal phase of polyelectrolyte as local drug delivery system for bone tuberculosis therapy.

    PubMed

    Wu, Gang; Chen, Long; Li, Hong; Deng, Chun-Ling; Chen, Xiao-Feng

    2014-01-01

    We use hydrophobic poly(lactic-co-glycolic) acid (PLGA) to encapsulate hydrophilic ofloxacin to form drug loading microspheres. Hyaluronic acid (HA) and polylysine (Pls) were used as internal phase additives to see their influences on the drug loading and releasing. Double emulsion (water-in-oil-in-water) solvent extraction/evaporation method was used for the purpose. Particle size analysis display that the polyelectrolytes have low impact on the microsphere average size and distribution. Scanning electron microscope (SEM) pictures show the wrinkled surface resulted by the internal microcavity of the microspheres. Microspheres with HA inside have higher drug loading amounts than microspheres with Pls inside. The loading drug amounts of the microspheres increase with the HA amounts inside, while decreasing with the Pls amounts inside. All the polyelectrolytes adding groups have burst release observed in experiments. The microspheres with Pls internal phase have faster release rate than the HA groups. Among the same polyelectrolyte internal phase groups, the release rate increases with the amounts increasing when Pls is inside, while it decreases with the amounts increasing when HA is inside. PMID:24707480

  4. 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.

  5. 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.

  6. Controlled release carrier of BSA made by W/O/W emulsion method containing PLGA and hydroxyapatite.

    PubMed

    Ho, Mei Ling; Fu, Yin Chih; Wang, Gwo Jaw; Chen, Hui Ting; Chang, Je Ken; Tsai, Tsung Hsien; Wang, Chih Kuang

    2008-06-01

    This study relates to the Bovine Serum Albumin (BSA) protein-controlled release system with Poly(lactic-glycolic acid) (PLGA) biodegradable polymer. It also has special double emulsification carriers containing alkaline material of hydroxyapatite (HAp), which can carry the hydrophilic drug effectively and sustain a controlled substance release. The controlled release strategy is based on the HAp absorption ability, which will be trapped into the core of PLGA microsphere. Besides, the acidic degradation products of PLGA polymer and basic inorganic component of HAp can be used to control the dissolution of microsphere, then resulting in protein release. We have varied the HAp amount to observe its effect on microsphere characteristics such as the particle size, surface/internal morphology, BSA entrapment efficiency, microsphere degradation, BSA in vitro release behaviour, and cell toxicity etc. PMID:18436324

  7. Investigations on hydroxyapatite powder obtained by wet precipitation

    NASA Astrophysics Data System (ADS)

    Poinescu, Aurora Anca; Ion, Rodica Mariana; van Staden, Raluca-Ioana; van Staden, Jacobus Frederick; Ghiurea, Marius

    2010-11-01

    It is well-known that hydroxyapatite have multiple applications in tissue engineering due to compositional similarities with bone tissue. In this work, hydroxyapatite powders obtained by modified chemical precipitation route, has been investigated by AMF and SEM analysis grain size, X-ray diffraction and infra-red spectroscopy. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 -60 nm. SEM observation of the HA coatings showed the presence of nano-sized needles, with a significant level of agglomeration. The infrared analysis show the characteristic peaks of absorbed water, hydroxyl, phosphate and carbonate species. The XRD pattern clearly indicated the crystallites responsible for the Bragg reflection of the (002) and (003) planes are useful for size determination by Sherrer relationship (around 68 nm).

  8. Study of thermal effects of silicate-containing hydroxyapatites

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Zaits, A. V.; Berdinskaya, N. V.; Mylnikova, T. S.

    2016-02-01

    The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 0C that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state.

  9. 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.

  10. 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).

  11. 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

  12. Nanophase hydroxyapatite coatings for dental and orthopedic applications

    NASA Astrophysics Data System (ADS)

    Sato, Michiko

    In order to improve dental and orthopedic implant performance, the objective of this study was to synthesize nanocrystalline hydroxyapatite (HA) powders to coat metals (specifically, titanium and tantalum). Precipitated HA powders were either sintered in order to produce UltraCaP HA (or microcrystalline size HA) or were treated hydrothermally to produce nanocrystalline HA. Some of the UltraCaP and nanocrystalline HA powders were doped with yttrium (Y) since previous in vitro studies demonstrated that Y-doped HA in bulk improved osteoblast (or bone-forming cell) function over undoped HA. The nanocrystalline HA powders were also mixed with nanophase titania powders because previous studies demonstrated that titania/HA composite coatings increased coating adhesive strength and HA nucleation. These powders were then deposited onto titanium by a novel room-temperature process, called IonTiteT(TM). The results demonstrated that the chemical properties and crystallite size of the original HA powders were maintained in the coatings. More importantly, in vitro studies showed increased osteoblast (bone-forming cell) adhesion on the single phase nanocrystalline HA and nano-titania/HA coatings compared to traditionally used plasma-sprayed HA coatings and uncoated metals. Results further demonstrated greater amounts of calcium deposition by osteoblasts cultured on nanocrystalline HA coatings compared to UltraCaP coatings and conventionally used plasma-sprayed HA coatings. To elucidate mechanisms that influenced osteoblast functions on the HA coatings, the amount of proteins (fibronectin and vitronectin) onto the HA powders and the adsorbed fibronectin conformation were investigated. Exposure of cell integrin binding domains (in fibronectin III10 segments) was greater in fibronectin adsorbed onto 1.2 mole% Y-doped UltraCaP HA coatings compared to nanocrystalline HA coatings tested. However, 1.2 mole% Y-doped UltraCaP HA coatings did not increase mineralization by osteoblasts compared to the nanocrystalline HA coatings. These results suggested that the availability of integrin binding domains in fibronectin did not correlate to enhanced mineralization by osteoblasts on nanocrystalline HA coatings. Lastly, undoped nanocrystalline HA coatings were studied using a well-established rat calvaria in vivo. Histological analysis showed that nanocrystalline HA coated on tantalum scaffolds increased bone and fibrous tissue infiltration into the scaffolds while uncoated and UltraCaP HA coated scaffolds did not after as early as 6 weeks. In summary, these results encourage further studies on nanocrystalline IonTiteTM HA coatings on various metals for orthopedic and dental applications.

  13. [Design of HA/Ti biomedical implants with the use of ion-beam-assisted deposition].

    PubMed

    Wang, C; Chen, Z

    1999-06-01

    Hydroxy-apatite (Ca10(PO4)6(OH)2,HA) is a potential material for coating on metal implants owing to its bioaffinity and osteo-integration to body. At present, in addition to bulk HA directly used in restoration and reconstruction surgery, hydroxy-apatite is also coated on metal implants by plasma-spraying method, adhesion and sintering. However, these kinds of biomaterials are restricted in application due to their insufficient strength and weak bonding. It is of great advantage to modify the surface of titanium and its alloy by ion-beam-assisted deposition (IBAD) combining ion implantation with physical vapor deposition(PVD). This paper is focused on the design of HA/Ti implants by ion-beam-assisted deposition technique and the computation of fabricating parameter using Trim96 program. The present investigation lays a foundation of further researches and application. PMID:12552649

  14. Novel selenium-doped hydroxyapatite coatings for biomedical applications.

    PubMed

    Rodríguez-Valencia, C; López-Álvarez, M; Cochón-Cores, B; Pereiro, I; Serra, J; González, P

    2013-03-01

    Nowadays there is a short-term need of investigating in orthopedic implants with a greater functionality, including an improved osseointegration and also antibacterial properties. The coating of metallic implants with hydroxyapatite (HA) remains to be the main proposal, but superior quality HA coatings with compositions closer to natural bone apatites, including carbonates, trace elements are required. Selenium is an essential nutrient in biological tissues and, at the same time, it also presents antibacterial properties. A pioneering study on the fabrication of selenium-doped carbonated hydroxyapatite (iHA:Se) coatings by Pulsed Laser Deposition (PLD) is presented. Different proportions of selenium were incorporated to obtain the iHA:Se coatings. Their physicochemical characterization, performed by SEM/EDS, FTIR, FT-Raman, Interferometric Profilometry and XPS, revealed typical columnar growth of HA in globular aggregates and the efficient incorporation of selenium into the HA coatings by the, most probably, substitution of SeO(3)(2-) groups in the CO(3)(2-) sites. Biological evaluation illustrated the absence of cytotoxicity when an amount of 0.6 at.% of Se was added to the iHA:Se coatings and excellent proliferation of the MC3T3-E1 preosteoblasts. Antibacterial properties were also proved with the inhibition of P. aeruginosa and S. aureus from establishing bacterial biofilms. PMID:22968925

  15. A Solid-State NMR Study of Selenium Substitution into Nanocrystalline Hydroxyapatite

    PubMed Central

    Kolmas, Joanna; Kuras, Marzena; Oledzka, Ewa; Sobczak, Marcin

    2015-01-01

    The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface. PMID:25997001

  16. Comparison of the Weibull characteristics of hydroxyapatite and strontium doped hydroxyapatite.

    PubMed

    Yatongchai, Chokchai; Wren, Anthony W; Curran, Declan J; Hornez, Jean-Christophe; Mark R, Towler

    2013-05-01

    The effects of two strontium (Sr) additions, 5% and 10% of the total calcium (Ca) content, on the phase assemblage and Weibull statistics of hydroxyapatite (HA) are investigated and compared to those of undoped HA. Sintering was carried out in the range of 900-1200 °C in steps of 1000 °C in a conventional furnace. Sr content had little effect on the mean particulate size. Decomposition of the HA phase occurred with Sr incorporation, while β-TCP stabilization was shown to occur with 10% Sr additions. Porosity in both sets of doped samples was at a comparable level to porosity in the undoped HA samples, however the 5% Sr-HA samples displayed the greatest reduction in porosity with increasing temperature while the porosity of the 10% Sr-HA samples remain relatively constant over the full sintering temperature range. The undoped HA samples displayed the greatest Weibull strengths and the porosity was determined to be the major controlling factor. However, with the introduction of decompositional phases in the Sr-HA samples, the dependence of strength on porosity is reduced and the phase assemblage becomes the more dominant factor for Weibull strength. The Weibull modulus is relatively independent of the porosity in the undoped HA samples. The 5% Sr-HA samples experience a slight increase in Weibull modulus with porosity, indicating a possible relationship between the parameters. However the 10% Sr-HA samples show the highest Weibull modulus with a value of approximately 15 across all sintering temperatures. It is postulated that this is due to the increased amount of surface and lattice diffusion that these samples undergo, which effectively smooths out flaws in the microstructure, due to a saturation of Sr content occurring in grain boundary movement. PMID:23524073

  17. Synthesis and characterization of strontium-doped hydroxyapatite powder via sol-gel method.

    PubMed

    Mardziah, C M; Sopyan, I; Hamdi, M; Ramesh, S

    2008-07-01

    Improvement of the mechanical properties of hydroxyapatite (HA) can be achieved by the incorporation of metal. In addition, incorporation of strontium ion into HA crystal structures has been proved effective to enhance biochemical properties of bone implant. In this research, strontium-doped HA powder was developed via a sol-gel method to produce extraordinarily fine strontium-doped HA (Sr-doped HA) powder. XRD measurement had shown that the powder contained hydroxyapatite phase only for all doping concentration except for 2%, showing that Sr atoms have suppressed the appearance of beta-TCP as the secondary phase. Morphological evaluation by FESEM measurement shows that the particles of the Sr-doped HA agglomerates are globular in shape with an average size of 1-2 microm in diameter while the primary particles have a diameter of 30-150 nm in average. PMID:19024993

  18. 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.

  19. 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.

  20. Iron(III) and manganese(II) substituted hydroxyapatite nanoparticles: Characterization and cytotoxicity analysis

    NASA Astrophysics Data System (ADS)

    Li, Yan; Teck Nam, Chai; Ooi, Chui Ping

    2009-09-01

    Calcium hydroxyapatite (HA) is the main inorganic component of natural bones and can bond to bone directly in vivo. Thus HA is widely used as coating material on bone implants due to its good osteoconductivity and osteoinductivity. Metal ions doped HA have been used as catalyst or absorbents since the ion exchange method has introduced new properties in HA which are inherent to the metal ions. For example, Mn2+ ions have the potential to increase cell adhesion while Fe3+ ions have magnetic properties. Here, Fe(III) substituted hydroxyapatite (Fe-HA) and Mn(II) substituted hydroxyapatite (Mn-HA) were produced by wet chemical method coupled with ion exchange mechanism. Compared with pure HA, the colour of both Fe-HA and Mn-HA nanoparticles changed from white to brown and pink respectively. The intensity of the colours increased with increasing substitution concentrations. XRD patterns showed that all samples were single phased HA while the FTIR spectra revealed all samples possessed the characteristic phosphate and hydroxyl adsorption bands of HA. However, undesired adsorption bands of carbonate substitution (B-type carbonated HA) and H2O were also detected, which was reasonable since the wet chemical method was used in the synthesis of these nanoparticles. FESEM images showed all samples were elongated spheroids with small size distribution and of around 70 nm, regardless of metal ion substitution concentrations. EDX spectra showed the presence of Fe and Mn and ICP-AES results revealed all metal ion substituted HA were non-stoichiometric (Ca/P atomic ratio deviates from 1.67). Fe-HA nanoparticles were paramagnetic and the magnetic susceptibility increased with the increase of Fe content. Based on the extraction assay for cytotoxicity test, both Fe-HA and Mn-HA displayed non-cytotoxicity to osteoblast.

  1. Additive manufactured Ti6Al4V scaffolds with the RF- magnetron sputter deposited hydroxyapatite coating

    NASA Astrophysics Data System (ADS)

    Chudinova, E.; Surmeneva, M.; Koptioug, A.; Scoglund, P.; Surmenev, R.

    2016-01-01

    Present paper reports on the results of surface modification of the additively manufactured porous Ti6Al4V scaffolds. Radio frequency (RF) magnetron sputtering was used to modify the surface of the alloy via deposition of the biocompatible hydroxyapatite (HA) coating. The surface morphology, chemical and phase composition of the HA-coated alloy were studied. It was revealed that RF magnetron sputtering allows preparing a homogeneous HA coating onto the entire surface of scaffolds.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Hydroxyapatite grafted carbon nanotubes and graphene nanosheets: Promising bone implant materials

    NASA Astrophysics Data System (ADS)

    Oyefusi, Adebola; Olanipekun, Opeyemi; Neelgund, Gururaj M.; Peterson, Deforest; Stone, Julia M.; Williams, Ebonee; Carson, Laura; Regisford, Gloria; Oki, Aderemi

    2014-11-01

    In the present study, hydroxyapatite (HA) was successfully grafted to carboxylated carbon nanotubes (CNTs) and graphene nanosheets. The HA grafted CNTs and HA-graphene nanosheets were characterized using FT-IR, TGA, SEM and X-ray diffraction. The HA grafted CNTs and graphene nanosheets (CNTs-HA and Gr-HA) were further used to examine the proliferation and differentiation rate of temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19). Total protein assays and western blot analysis of osteocalcin expression were used as indicators of cell proliferation and differentiation. Results indicated that hFOB 1.19 cells proliferate and differentiate well in treatment media containing CNTs-HA and graphene-HA. Both CNTs-HA and graphene-HA could be promising nanomaterials for use as scaffolds in bone tissue engineering.

  8. Rod-shaped and substituted hydroxyapatite nanoparticles stimulating type 1 and 2 cytokine secretion.

    PubMed

    Wang, Xiupeng; Li, Xia; Ito, Atsuo; Watanabe, Yohei; Sogo, Yu; Hirose, Motohiro; Ohno, Tadao; Tsuji, Noriko M

    2016-03-01

    A Th1 immune response is required for modern vaccines as the most commonly used alum adjuvant has weak capacity for inducing Th1 immune response. Herein, rod-shaped hydroxyapatite (HA), magnesium-substituted HA (MgHA) and zinc-substituted HA (ZnHA) nanoparticles with irregular nanopores were synthesized and used as immunoadjuvants. Magnesium and zinc substitution in HA showed no influence on morphology, particle size, zeta potential and surface area of the nanoparticles. The rod-shaped MgHA and ZnHA nanoparticles promoted the cellular uptake of a molecular immunopotentiator, stimulated both type 1 and 2 cytokine secretion in vitro that relate to Th1 and Th2 immunity of bone marrow dentritic cells, respectively. The MgHA and ZnHA nanoparticles may be useful as immunoadjuvants for human. PMID:26700228

  9. Surface modification of zinc-containing hydroxyapatite by tartaric acid

    NASA Astrophysics Data System (ADS)

    Turki, Thouraya; Othmani, Masseoud; Bac, Christophe Goze; Rachdi, Frid; Bouzouita, Khaled

    2013-11-01

    The surface of Zn-substituted hydroxyapatites (Ca(10-x)Znx(PO4)6(OH)2, with 0 ? x ? 2, CaxZnxHA) modified by tartaric acid was investigated by various techniques. XRD powder patterns revealed that synthesized samples were single phase of HA with broadened XRD reflections. FTIR and (13C, 1H and 31P) MAS NMR measurements confirmed the grafting of the tartaric acid on the apatite surface. Chemical analysis showed that for ZnHA the grafted acid amount increases with the increase of the acid concentration in the starting solutions, while for HA, it remained constant, indicating more reactivity for ZnHA surface. A mechanism of surface modification is proposed based on the obtained results.

  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. Preparation of Porous Hydroxyapatite Tablets and Porous Hydroxyapatite Coatings for Orthopaedic Use

    NASA Astrophysics Data System (ADS)

    Méndez-González, M.

    2004-09-01

    Porous hydroxyapatite tablets and coatings on metal substrates were obtained by the addition of polymeric additives and liofilization. Both tablets and coatings were characterized by scanning electron microscopy and x-ray diffraction. Coatings obtained by plasma spraying also exhibited interconnected porous of 100 μm while coatings obtained by laser ablation did not show any porosity. The diffraction patterns of the deposited HA were similar to that of the powder obtained by the precipitation method suggesting that no significant changes occurred during the coating procedure.

  12. Effect of hydroxyapatite morphology/surface area on the rheology and processability of hydroxyapatite filled polyethylene composites.

    PubMed

    Joseph, R; McGregor, W J; Martyn, M T; Tanner, K E; Coates, P D

    2002-11-01

    The commercial success of hydroxyapatite (HA) filled polyethylene composite has generated growing interest in improving the processability of the composite. A number of synthetic procedures and post synthesis heat treatment of HA has lead to the availability of powders with widely varying morphological features. This paper addresses the effect of morphological features of HA on the rheology and processability of an injection-moulding grade HA-HDPE composite. The results showed that low surface area HA filled composite exhibited better injection processing characteristics through improved rheological responses. The effect of reducing the surface area of the filler is to require less polyethylene to wet the filler and allows more polyethylene to be involved in the flow processes. These changes reduced the temperatures and pressures required for successful processing. PMID:12194532

  13. In vitro evaluation of the risk of inflammatory response after chitosan/HA and chitosan/β-1,3-glucan/HA bone scaffold implantation.

    PubMed

    Przekora, Agata; Ginalska, Grazyna

    2016-04-01

    The aim of the study was to evaluate in vitro the risk of inflammatory response induced by chitosan/hydroxyapatite (chit/HA) and novel chitosan/β-1,3-glucan/hydroxyapatite (chit/glu/HA) bone scaffolds. The inflammatory response was assessed via measurement of proinflammatory cytokine and ROI production by human monocytes, macrophages, and osteoblasts stimulated with investigated scaffolds. Moreover, adsorption of human serum/plasma proteins to the tested materials was determined. Both biomaterials did not induce intracellular ROI generation by monocytes, macrophages, and osteoblasts and did not stimulate proinflammatory cytokine (IL-6 and TNF-α) production by inflammatory cells. Moreover, the chit/glu/HA material induced increased TNF-α production by osteoblasts that is believed to enhance osteogenic differentiation. Thus, it was demonstrated that chit/HA and chit/glu/HA scaffolds carry a low risk of biomaterial-induced inflammatory response and are promising materials as bone scaffolds for bone tissue engineering and regenerative medicine applications. PMID:26838861

  14. Synergistic interaction of platelet derived growth factor (PDGF) with the surface of PLLA/Col/HA and PLLA/HA scaffolds produces rapid osteogenic differentiation.

    PubMed

    Raghavendran, Hanumantha Rao Balaji; Mohan, Saktiswaren; Genasan, Krishnamurithy; Murali, Malliga Raman; Naveen, Sangeetha Vasudevaraj; Talebian, Sepehr; McKean, Robert; Kamarul, Tunku

    2016-03-01

    Scaffolds with structural features similar to the extracellular matrix stimulate rapid osteogenic differentiation in favorable microenvironment and with growth factor supplementation. In this study, the osteogenic potential of electrospun poly-l-lactide/hydroxyapatite/collagen (PLLA/Col/HA, PLLA/HA and PLLA/Col) scaffolds were tested in vitro with the supplementation of platelet derived growth factor-BB (PDGF-BB). Cell attachment and topography, mineralization, extracellular matrix protein localization, and gene expression of the human mesenchymal stromal cells were compared between the fibrous scaffolds PLLA/Col/HA, PLLA/Col, and PLLA/HA. The levels of osteocalcin, calcium, and mineralization were significantly greater in the PLLA/Col/HA and PLLA/HA compared with PLLA/Col. High expression of fibronectin, intracellular adhesion molecule, cadherin, and collagen 1 (Col1) suggests that PLLA/Col/HA and PLLA/HA scaffolds had superior osteoinductivity than PLLA/Col. Additionally, osteopontin, osteocalcin, osterix, Runt-related transcription factor 2 (Runx2), and bone morphogenic protein (BMP2) expression were higher in PLLA/Col/HA and PLLA/HA compared with PLLA/Col. In comparison with PLLA/Col, the PLLA/Col/HA and PLLA/HA scaffolds presented a significant upregulation of the genes Runx2, Col 1, Integrin, osteonectin (ON), bone gamma-carboxyglutamic acid-containing protein (BGALP), osteopontin (OPN), and BMP2. The upregulation of these genes was further increased with PDGF-BB supplementation. These results show that PDGF-BB acts synergistically with PLLA/Col/HA and PLLA/HA to enhance the osteogenic differentiation potential. Therefore, this combination can be used for the rapid expansion of bone marrow stromal cells into bone-forming cells for tissue engineering. PMID:26700235

  15. 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

  16. Effect of Hydrothermal Treatment on Sinterability of Hydroxyapatite

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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 °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 °C, 900 °C and 1000 °C for 10 min with the heating rate of 25 °Cṡmin-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 °C, 900 °C and 1000 °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 °C and 1000 °C.

  17. Production of hydroxyapatite from waste mussel shells

    NASA Astrophysics Data System (ADS)

    Jones, Mark I.; Barakat, Haneen; Patterson, Darrell Alec

    2011-10-01

    This work describes the formation of Hydroxyaptite, Ca10(PO4)6(OH)2, from waste mussel shells from the New Zealand aquaculture industry. The raw shells are first calcined to produce lime (CaO) and then reacted in a purpose built reactor to form the Hydroxyapatite (HA) in a low temperature batch process. The calcination was studied in terms of the effects of temperature, heating rate, holding time, nitrogen flow rate and particle size. The crystals formed in the batch reactor were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Photoelectron Spectroscopy (XPS). Optimised conditions in the calcination stage resulted in powder with around 95% conversion to lime. The as-produced HA showed poor crystallinity and the presence of impurities, although both of these features were improved by a suitable post heat treatment process. The post treated material showed good crystallinity and was comparable to commercially produced material. Preliminary biocompatibility experiments showed that the HA stimulated cell growth and promoted mineralization. The production of HA from mussel shells in a room temperature, ambient pressure process is not only a sustainable use of waste material, but also from an industrial point of view the process has considerable potential for reducing costs associated with both starting materials and energy.

  18. 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.

  19. Influence of manganese doping into HA powders on the properties of its dense bodies.

    PubMed

    Natasha, A N; Sopyan, I; Mel, M; Ramesh, S

    2008-07-01

    The effect of Manganese (Mn) addition on the Vickers hardness and relative density of nanocrystalline hydroxyapatite (HA) dense bodies were studied. The starting Mn doped HA powders was synthesized via sol-gel method with Mn concentration varies from 2 mol% up to 15 mol% Mn. The Mn doped HA disc samples were prepared by uniaxial pressing at 200MPa and subsequently sintered at 1300 degrees C. Characterization was carried out where appropriate to determine the phases present, bulk density, Vickers hardness of the various content of Mn doped HA dense bodies. The addition of Mn was observed to influence the color appearance of the powders and dense bodies as well. Higher Mn concentration resulted in dark grey powders. It was also found that the hardness and relative density of the material increased as the Mn content increased and influenced by the crystallinity of the prepared Mn doped HA powders. PMID:19024996

  20. Carbon nanotubes/hydroxyapatite nanocomposites fabricated by spark plasma sintering for bonegraft applications

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhu, Yuhe; Watari, Fumio; Liao, Susan; Yokoyama, Atsuro; Omori, Mamoru; Ai, Hongjun; Cui, FuZhai

    2012-12-01

    Multi-wall carbon nanotubes/hydroxyapatite (MWCNTs/HA) composites with 20%, 40% and 60% HA were successfully fabricated at 1200 °C and 120 MPa by spark plasma sintering (SPS). Scanning electron microscope (SEM) observations showed that MWCNTs/HA composites kept the nanostructure of MWCNTs after SPS treatment. The bulk density of the MWCNTs/HA composites was increased by the addition of HA. However, the Vickers hardness, porosity, Young's modulus, flexure strength and compression strength of the MWCNTs/HA composites were decreased with increasing content of HA. To test their biocompatibility, the MWCNTs/40% HA composites were inserted into rat femur. The in vivo reaction of four weeks showed that the composites possessed better osseointegration compared to pure MWCNTs. The results indicated that the MWCNTs/HA composites have potential for a wide variety of bonegraft applications in the future.

  1. Adrenomedullin delivery in microsphere-scaffold composite for remodeling of the alveolar bone following tooth extraction: an experimental study in the rat

    PubMed Central

    2013-01-01

    Background Alveolar ridge resorption, as a significant problem in implant and restorative dentistry, has long been considered as an inevitable outcome following tooth extraction. Recently, adrenomedullin (ADM) is reported to be able to stimulate the proliferation and migration of various cells including osteoblasts. The purpose of this study was to investigate the influence of local ADM application in the tooth extraction socket in vivo. Methods Chitosan micropheres were developed by an emulsion-ionic cross-linking method for ADM delivery. Poly (L -lactic-co-glycolic) acid (PLGA) and nano-hydroxyapatite (nHA) were used to prepare scaffolds to contain the micrspheres with ADM. In vivo experiment was evaluated by transplanting the composite into the rat socket right after the incisor extraction. After 4, 8, 12 weeks implantation, radiographic and histological tests were carried out to evaluate the effect of released ADM on the alveolar bone. Results The microspheres had a spherical structure and a relative rough and uniform surface, and the particle size was under a normal distribution, with the average diameter of 38.59 μm. The scaffolds had open and interconnected pores. In addition, the high porosity of the composite was 88.93%. Radiographic and histological examination revealed that the PLGA/nHA/CMs/ADM composite could accelerate the alveolar bone remodeling and reduce the residual ridge resorption compared with the PLGA/nHA/CMs scaffold. Conclusions The results of this study suggest that local application of ADM has the potential to preserve the residual alveolar ridge and accelerate the alveolar bone remodeling. PMID:24099554

  2. Effect of hydroxyapatite-based biomaterials on human osteoblast phenotype.

    PubMed

    Trombelli, L; Penolazzi, L; Torreggiani, E; Farina, R; Lambertini, E; Vecchiatini, R; Piva, R

    2010-03-01

    The present study evaluated human primary osteoblasts and two different osteoblast-like cell lines behaviour when cultured in presence of different hydroxyapatite-based (HA) biomaterials (SINTlife-FIN-CERAMICA S.p.a., Faenza, Italy; Bio-Oss, Geistlich Biomaterials, Woulhusen, Switzerland; Biostite-GABA Vebas, San Giuliano Milanese, MI, Italy), focusing attention on the effect of HA/Biostite in terms of modulation of osteoblastic differentiation. Analysis were about adhesion, proliferation and mineralization activity. Runt-related transcription factor 2 (Runx2), Estrogen Receptor alpha (ERalfa) expression and alkaline phosphatase activity (ALP) were measured as osteoblastic differentiation markers. Determination of viable cells was done with MTT colorimetric assay. Scanning electron microscopy (SEM) analysis was performed on biomaterial-treated cells. All hydroxyapatite-based biomaterials didn't affect cells morphology and viability, whereas only presence of HA/Biostite improved cells adhesion, growth and differentiation. Adhesion and spreading of the primary cells on HA/Biostite were the same showed by two different osteoblast-like cell lines. These results have important implications for both tissue-engineered bone grafts and enhancement of HA implants performance, to develop new teeth's supporting structure therapies and replacement. PMID:20357737

  3. Effect of trisodium citrate on electrolytic deposition of hydroxyapatite coatings.

    PubMed

    Lin, Dong-Yang; Wang, Xiao-Xiang; Jiang, Yong

    2011-01-01

    Hydroxyapatite coatings were deposited on the titanium substrate by using various content Na₃Cit as an organic modifier in electrolytes. The influence of the Na₃Cit on the sizes of the HA crystals during electrolytic deposition was investigated under different molar ratio of Na₃Cit to calcium ions. The experimental results showed that the size of HA crystal was well controlled by the addition of Na₃Cit. When the molar ratio of Na₃Cit to calcium ions was equal or greater than five, the obtained HA coating consisted of nanosized crystals. The HA nanoparticles were precipitated without a precursor phase when the molar ratio of Na₃Cit to calcium ions was five; otherwise, the CaP coating experienced a phase conversion from octacalcium phosphate (OCP) to HA during the ELD. The effect of pH on saturation indexes with respect to hydroxyapatite, OCP, and dicalcium dihydrogen phosphate of these electrolytes was calculated by a computer program PHREEQC. The calculation showed the nucleation of OCP as the precursor during the deposition could be inhibited with increasing Na₃Cit content in the electrolytes. PMID:21086428

  4. Hydroxyapatite-titanium bulk composites for bone tissue engineering applications.

    PubMed

    Kumar, Alok; Biswas, Krishanu; Basu, Bikramjit

    2015-02-01

    The research work on bulk hydroxyapatite (HA)-based composites are driven by the need to develop biomaterials with better mechanical properties without compromising its bioactivity and biocompatibility properties. Despite several years of research, the mechanical properties of the HA-based composites still need to be enhanced to match the properties of natural cortical bone. In this regard, the scope of this review on the HA-based bulk biomaterials is limited to the processing and the mechanical as well as biocompatibility properties for bone tissue engineering applications of a model system that is hydroxyapatite-titanium (HA-Ti) bulk composites. It will be discussed in this review how HA-Ti based bulk composites can be processed to have better fracture toughness and strength without compromising biocompatibility. The advantages of the functionally gradient materials to integrate the mechanical and biocompatibility properties is a promising approach in hard tissue engineering and has been emphasized here in reference to the limited literature reports. On the biomaterials fabrication aspect, the recent results are discussed to demonstrate that advanced manufacturing techniques, like spark plasma sintering can be adopted as a processing route to restrict the sintering reactions, while enhancing the mechanical properties. Various toughening mechanisms related to careful tailoring of microstructure are discussed. The in vitro cytocompatibilty, cell fate processes as well as in vivo biocompatibility results are also reviewed and the use of flow cytometry to quantify in vitro cell fate processes is being emphasized. PMID:24737723

  5. 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.

  6. 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.

  7. 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. PMID:21485810

  8. Anisotropic growth of hydroxyapatite on the silk fibroin films

    NASA Astrophysics Data System (ADS)

    Li, Yucheng; Cai, Yurong; Kong, Xiangdong; Yao, Juming

    2008-12-01

    Bombyx mori silk fibroin is of practical interest for its excellent intrinsic properties utilizable in the biotechnological and biomedical fields. Here, the silk fibroin films were pretreated with different methods and then used as the template for the hydroxyapatite (HA) crystal growth. To study the effect of silk films' surface structure on the protein biomineralization, the films were immersed into 1.5 times simulated body fluid (1.5 × SBF) to induce the HA deposition at 37 °C. The results showed that an anisotropic growth of HA crystals was observed on the different films as judging from XRD, TEM and HRTEM data. This was thought that the positions and density of carboxyl groups, C dbnd O and amino groups on the surface of SF films may be different, which play the key effect on HA crystal growth.

  9. Dissolution of calcium-deficient hydroxyapatite synthesized at different conditions

    SciTech Connect

    Mavropoulos, Elena; Rossi, Alexandre M.; Rocha, Nilce C.C. da; Soares, Gloria A.; Moreira, Josino C.; Moure, Gustavo T

    2003-03-15

    The dissolution characteristics of several calcium-deficient hydroxyapatites (HA) have been investigated. Eleven samples were produced by varying synthesis parameters like temperature, pH, digestion time, reagent concentration and velocity of addition. Powder characterization was conducted using X-ray diffraction. Sample crystallinity was variable and samples examined by transmission electron microscopy showed acicular or plate-like morphology. After sample dissolution in Milli-Q water for 168 h, the calcium and phosphate contents in solution were measured by induced coupled plasma optical emission spectrometry (OES). The dissolution behavior of calcium-deficient HA was highly dependent on the sample calcium/phosphorus (Ca/P) molar ratio of the original HA. Dissolution in water was enhanced with decreasing HA sample molar ratio. However, the dissolution process equilibrium was not achieved at the end of 168 h (7 days)

  10. Antibacterial Property of Cold-Sprayed HA-Ag/PEEK Coating

    NASA Astrophysics Data System (ADS)

    Sanpo, Noppakun; Tan, Meng Lu; Cheang, Philip; Khor, K. A.

    2009-03-01

    The antibacterial behavior of HA-Ag (silver-doped hydroxyapatite) nanopowder and their composite coatings were investigated against Escherichia coli (DH5α). HA-Ag nanopowder and PEEK (poly-ether-ether-ketone)-based HA-Ag composite powders were synthesized using in-house powder processing techniques. Bacteria culture assay of HA-Ag nanopowder and their composite powders displayed excellent bacteriostatic activity against E. coli. The antibacterial activity increased with increasing concentration of HA-Ag nanoparticle in these composite powders. These nanocomposite powders were subsequently used as feedstock to generate antibacterial coatings via cold spray technology. The ratios of HA-Ag to PEEK in their composite powders were 80:20, 60:40, 40:60, and 20:80 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and XRD. Antibacterial nanocomposite HA-Ag/PEEK coatings were successfully deposited using cold spraying parameters of 11-12 bars at preheated air temperature between 150 and 160 °C. These as-sprayed coatings of HA-Ag/PEEK composite powders comprising varying HA-Ag and PEEK ratios retained their inherent antibacterial property as verified from bacterial assay. The results indicated that the antibacterial activity increased with increasing HA-Ag nanopowder concentration in the composite powder feedstock and cold-sprayed coating.

  11. 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.

  12. Osteoblast response to hydroxyapatite doped with divalent and trivalent cations.

    PubMed

    Webster, Thomas J; Massa-Schlueter, Elizabeth A; Smith, Jennifer L; Slamovich, Elliot B

    2004-05-01

    The present in vitro study doped hydroxyapatite (HA) with various metal cations (Mg(2+), Zn(2+), La(3+), Y(3+), In(3+), and Bi(3+)) in an attempt to enhance properties of HA pertinent to orthopedic and dental applications. X-ray diffraction material characterization indicated that the metal cations may have substituted for calcium in the HA crystal structure and that all of the doped HA formulations were single-phase and crystalline. Scanning electron microscopy analysis revealed a variety of grain sizes, depending on the dopant utilized. Energy-dispersive spectroscopy confirmed that the dopants added during synthesis were present and that all of the HA formulations synthesized were within the defined range of HA phase in the CaO-P(2)O(5)-H(2)O system. Lastly, Bi-doped HA had a slower dissolution rate than either undoped HA or HA doped with other cations when exposed to simulated physiological conditions for 21 days. In terms of cell function, results provided the first evidence that osteoblasts, bone-forming cells, adhered and differentiated (as measured by alkaline phosphatase synthesis) in response to HA doped with trivalent cations (specifically, La(3+), Y(3+), In(3+), Bi(3+)) at earlier time points than either HA doped with divalent cations (Mg(2+), Zn(2+)) or undoped HA. Of the dopants examined, Bi(3+) most enhanced osteoblast long-term calcium-containing mineral deposition. For these reasons, this study revealed for the first time the potential benefits of doping HA with Bi(3+) according to criteria critical for bone prosthetic clinical success. PMID:14741626

  13. A citric acid-based hydroxyapatite composite for orthopedic implants.

    PubMed

    Qiu, Hongjin; Yang, Jian; Kodali, Pradeep; Koh, Jason; Ameer, Guillermo A

    2006-12-01

    We describe a novel approach to process bioceramic microparticles and poly(diol citrates) into bioceramic-elastomer composites for potential use in orthopedic surgery. The composite consists of the biodegradable elastomer poly(1,8-octanediol-citrate) (POC) and the bioceramic hydroxyapatite (HA). The objective of this work was to characterize POC-HA composites and assess the feasibility of fabricating tissue fixation devices using machining and molding techniques. The mechanical properties of POC-HA composites with HA (40, 50, 60, 65wt.%) were within the range of values reported for tissue fixation devices (for POC-HA 65wt.%, S(b)=41.4+/-3.1, E(b)=501.7+/-40.3, S(c)=74.6+/-9.0, E(c)=448.8+/-27.0, S(t)=9.7+/-2.3, E(t)=334.8+/-73.5, S(s)=27.7+/-2.4, T(s)=27.3+/-4.9, all values in MPa). At 20 weeks, the weight loss of POC-HA composites ranged between 8 and 12wt.%, with 65wt.% HA composites degrading the slowest. Exposure of POC-HA to simulated body fluid resulted in extensive mineralization in the form of calcium phosphate with Ca/P of 1.5-1.7 similar to bone. POC-HA supported osteoblast adhesion in vitro and histology results from POC-HA samples that were implanted in rabbit knees for 6 weeks suggest that the composite is biocompatible. Synthesis of POC-HA is easy and inexpensive, does not involve harsh solvents or initiators, and the mechanical properties of POC-HA with 65wt.% HA are suitable for the fabrication of potentially osteoconductive bone screws. PMID:16919720

  14. Chemical characterization of some substituted hydroxyapatites

    PubMed Central

    2011-01-01

    Synthetic multi-substituted hydroxyapatite nano powders containing silicon and or carbonate prepared by a wet chemical method. The process parameters are set up to allow the simultaneous substitution of carbonate and silicon ions in the place of phosphorus. The chemical and structural characterizations of the prepared powders are determined with the aid of; XRF, ICP, XRD and FTIR. The results show that, the ion substitution in the crystal lattice of HA caused a change in the unit cell dimensions and affected the degree of crystallization of the produced powders. The apatite formation abilityy of the prepared discs from the synthesized powders is determined by immersing in SBF solution for different periods. The degree of ion release was determined in the obtained solutions. The examined surface of the immersed discs under SEM and analyzed by CDS showed a more dense HA layer than those of un-substituted ones. The HA with the substituted silicon and carbonate ions, showed the highest solubility with greater rate of ion release, compared with carbonate-free powder. All prepared powders took sodium ion from the SBF solution during immersion, which was not recorded before. PMID:22122971

  15. Single-walled carbon nanotubes/hydroxyapatite coatings on titanium obtained by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Pei, Xibo; Zeng, Yongxiang; He, Rui; Li, Zhongjie; Tian, Lingyang; Wang, Jian; Wan, Qianbing; Li, Xiaoyu; Bao, Hong

    2014-03-01

    Single-walled carbon nanotubes/hydroxyapatite (SWNTs/HA) composite coatings were successfully fabricated by electrochemical deposition technique. Different concentrations of SWNTs were incorporated into the apatite coating by adding functionalized SWNTs into the electrolyte. Homogeneous and crack-free SWNTs/HA composite coatings were achieved and the coatings had higher crystallinity compared to pure HA coating. In addition, the highest bonding strength of the SWNTs/HA coating reached 25.7 MPa, which was nearly 70% higher than that of pure HA coating. The in-vitro cellular biocompatibility tests revealed that SWNTs/HA composite coatings exhibited higher in-vitro bioactivity than that of pure HA coating and pure titanium (Ti). It suggests that SWNTs/HA composite coating may have enormous potential applications in the field of biomaterials, especially for the metal implants.

  16. 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 35nm 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. PMID:26952486

  17. Synthesis of nano-hydroxyapatite and its rapid mediated surface functionalization by silane coupling agent.

    PubMed

    Rehman, Sarish; Khan, Kishwar; Mujahid, Mohammad; Nosheen, Shaneela

    2016-01-01

    In this work, hydroxyapatite (HA) nanorods were synthesized by simple one step wet precipitation method followed by their rapid surface functionalization via aminopropyltriethoxysilane (APTS) to give modified (HA-APTS) product. Functionalized hydroxyapatite (HA-APTS) holds amino groups on their surface that can be further functionalized with other bioactive molecules. The extent of functionalization of HA was studied under three different processing conditions; at room temperature, at 80 °C and under microwave condition (600 W). Three different temperatures have been use for the purpose of comparison between the functionalized products so that we can judge that whether there is any effect of temperature on the final products. In the last we conclude that temperature has no effect. So microwave condition is best to carried out the functionalization in just 5 min. PMID:26478359

  18. Synthesis and characterization of hydroxyapatite from fish bone waste

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  19. 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)

  20. Luminescence studies of rare-earth doped and Co-doped hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Vasugi, G.; Thamizhavel, A.; Girija, E. K.

    2012-06-01

    Rare-earth doped and co-doped hydroxyapatite (Eu: HA, Eu-Y: HA) were prepared by wet precipitation method by using CTAB as the organic modifier. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Photoluminescence spectra (PL). Upon excitation at 350 nm the samples Eu: HA and Eu-Y: HA shows the emission band in the visible region, which makes it suitable for potential application such as bio-imaging.

  1. Thin hydroxyapatite coating on AZ91D magnesium alloy fabricated via RF-magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mukhametkaliyev, T. M.; Surmeneva, M. A.; Mueller, M.; Prymak, O.; Epple, M.; Surmenev, R. A.

    2015-11-01

    In this study the morphology, composition, structure and wettability of radiofrequency (RF) magnetron sputter-deposited hydroxyapatite (HA) coating deposited on the surface of AZ91D magnesium alloy were investigated. The results revealed that the fabricated coating is uniform, homogeneous with the structure of the stoichiometric HA. The deposition of the HA coating did not change significantly the surface wettability of the bare alloy, however water contact angle dynamics in the case of the HA coated substrates revealed a lower rate of a droplet spreading over the surface.

  2. 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. PMID:25842126

  3. Magnesium substituted hydroxyapatite formation on (Ti,Mg)N coatings produced by cathodic arc PVD technique.

    PubMed

    Onder, Sakip; Kok, Fatma Nese; Kazmanli, Kursat; Urgen, Mustafa

    2013-10-01

    In this study, formation of magnesium substituted hydroxyapatite (Ca10-xMgx(PO4)6(OH)2) on (Ti,Mg)N and TiN coating surfaces were investigated. The (Ti1-x,Mgx)N (x=0.064) coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition technique. TiN coated grade 2 titanium substrates were used as reference to understand the role of magnesium on hydroxyapatite (HA) formation. The HA formation experiments was carried out in simulated body fluids (SBF) with three different concentrations (1X SBF, 5X SBF and 5X SBF without magnesium ions) at 37 °C. The coatings and hydroxyapatite films formed were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and FTIR Spectroscopy techniques. The energy dispersive X-ray spectroscopy (EDS) analyses and XRD investigations of the coatings indicated that magnesium was incorporated in the TiN structure rather than forming a separate phase. The comparison between the TiN and (Ti, Mg)N coatings showed that the presence of magnesium in TiN structure facilitated magnesium substituted HA formation on the surface. The (Ti,Mg)N coatings can potentially be used to accelerate the HA formation in vivo conditions without any prior hydroxyapatite coating procedure. PMID:23910351

  4. 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).

  5. In Situ Hydroxyapatite Content Affects the Cell Differentiation on Porous Chitosan/Hydroxyapatite Scaffolds.

    PubMed

    Rogina, Anamarija; Rico, Patricia; Gallego Ferrer, Gloria; Ivanković, Marica; Ivanković, Hrvoje

    2016-04-01

    Highly porous chitosan/hydroxyapatite composite structures with different weight ratios (100/0; 90/10; 80/20; 70/30; 60/40; 50/50; 40/60) have been prepared by precipitation method and freeze-gelation technique using calcite, urea phosphate and chitosan as starting materials. The composition of prepared composite scaffolds was characterized by X-ray diffraction analysis and Fourier transformed infrared spectroscopy, while morphology of scaffolds was imaged by scanning electron microscopy. Mercury intrusion porosimetry measurements of prepared scaffolds have shown different porosity and microstructure regarding to the HA content, along with SEM observations of scaffolds after being immersed in physiological medium. The results of swelling capacity and compressive strength measured in Dulbecco's phosphate buffer saline (DPBS) have shown higher values for composite scaffolds with lower in situ HA content. Viability, proliferation and differentiation of MC3T3-E1 cells seeded on different scaffolds have been evaluated by live dead assay and confocal scan microscopy. Our results suggest that the increase of HA content enhance osteoblast differentiation confirming osteogenic properties of highly porous CS/HA scaffolds for tissue engineering applications in bone repair. PMID:26265459

  6. Particle Tracking of Fluorescent Microspheres

    NASA Astrophysics Data System (ADS)

    Kaminski, Zofia; Mueller, Joachim; Berk, Serkan

    2010-10-01

    In this research, the diffusion coefficients of the fluorescent microspheres and the relation of those coefficients to particle radius were investigated. An additional focus was to see how well the measured radius of the microspheres compared to the radius as reported by the manufacturer and to measure the distribution of radii in a sample. This study further developed the critical process of ensuring particle movement within the sample volume and made preliminary sample measurements.The methods developed for tracking microspheres will later be used to determine the radii of virus like particles (VLPs), which are a non-infectious model system of the HIV virus. Results from our measurements will be reported.

  7. 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. PMID:24642972

  8. 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. PMID:18615683

  9. 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

  10. 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. PMID:26083784

  11. 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 Ca2+ concentration enabled the HA crystallization process to be growth dominated, producing films composed of high crystallinity, hexagonal grains on multiple metallic substrates. TEP regulation of HA crystallization enabled the deposition of an adhesive CaTiO3 intermediate layer, and then HA in a continuous, phase sequenced process on Ti6Al4V substrates, the first such process reported in the hydrothermal HA literature. The HA film was found to be deposited by a passivating competitive growth mechanism that enabled the [0001] crystallographic orientation of hexagonal single crystals to be engineered with synthesis time. Bioactivity analysis demonstrated that films were bioactive and bone bonding. Together, these results suggest that these HA films are candidates for use on metallic orthopedic implants, namely Ti6Al4V.

  12. 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.

  13. 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

  14. 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 ability.

  15. 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. PMID:23045363

  16. 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. PMID:21850513

  17. 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 manufacturing of the microspheres, while sorting entails deciphering the good microspheres from the bad ones. Each process is discussed in detail.

  18. Osteogenic Responses to Zirconia with Hydroxyapatite Coating by Aerosol Deposition

    PubMed Central

    Cho, Y.; Hong, J.; Ryoo, H.; Kim, D.; Park, J.

    2015-01-01

    Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. PMID:25586588

  19. Osteogenic responses to zirconia with hydroxyapatite coating by aerosol deposition.

    PubMed

    Cho, Y; Hong, J; Ryoo, H; Kim, D; Park, J; Han, J

    2015-03-01

    Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. PMID:25586588

  20. 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. PMID:26838882

  1. In Vitro Evaluation of Hydroxyapatite-Coated Titanium Implant with Atmospheric Plasma Treatment.

    PubMed

    Lee, Hyo-Jin; Kwon, Tae-Yub; Kim, Kyo-Han; Kang, Seong Soo; Choi, Seok Hwa; Kwon, Soon-Taek; Cho, Dae-Hyun; Son, Jun Sik

    2015-08-01

    Plasma treatments are becoming a popular method for modifying the characteristics of a range of substrate surfaces. Atmospheric pressure plasma (APP) is cost-efficient, safe and simple compared to high-pressure plasma. This study examined the effects of a low-temperature APP treatment of a hydroxyapatite (HA)-coated Ti (HA-Ti) surface. The APP treatment made the HA-Ti surfaces more hydrophilic without changing surface morphologies. The APP-treated HA-Ti (APP-HA-Ti) surface showed enhanced cell spreading, cell proliferation, and alkaline phosphatase (ALP) levels with more developed cellular networks, and the formed extracellular matrix (ECM) was fused perfectly with the HA substrate than that on the HA-Ti surface. In conclusion, an APP treatment is a potential surface-modifying method that can enhance the cell affinity at the early stages in vitro. PMID:26369123

  2. 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. PMID:25175191

  3. Thin-Layer Hydroxyapatite Deposition on a Nanofiber Surface Stimulates Mesenchymal Stem Cell Proliferation and Their Differentiation into Osteoblasts

    PubMed Central

    Proseck, Eva; Buzgo, Matej; Rampichov, Michala; Kocourek, Tom; Kochov, Petra; Vyslouilov, Lucie; Tvrdk, Daniel; Jelnek, Miroslav; Luk, David; Amler, Even

    2012-01-01

    Pulsed laser deposition was proved as a suitable method for hydroxyapatite (HA) coating of coaxial poly-?-caprolactone/polyvinylalcohol (PCL/PVA) nanofibers. The fibrous morphology of PCL/PVA nanofibers was preserved, if the nanofiber scaffold was coated with thin layers of HA (200?nm and 400?nm). Increasing thickness of HA, however, resulted in a gradual loss of fibrous character. In addition, biomechanical properties were improved after HA deposition on PCL/PVA nanofibers as the value of Young's moduli of elasticity significantly increased. Clearly, thin-layer hydroxyapatite deposition on a nanofiber surface stimulated mesenchymal stem cell viability and their differentiation into osteoblasts. The optimal depth of HA was 800?nm. PMID:22319242

  4. 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 12weeks. 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. PMID:26952418

  5. Development of wear resistant NFSS-HA novel biocomposites and study of their tribological properties for orthopaedic applications.

    PubMed

    Younesi, M; Bahrololoom, M E; Fooladfar, H

    2010-02-01

    Implants made of nickel free austenitic stainless steel can reduce the toxic effect of released nickel ion and compounds from the conventional stainless steels. On the other hand, hydroxyapatite is a ceramic which has been used in orthopaedic applications due to its good osteoconductivity, biocompatibility and bioactivity. However, there is no evidence in the literature up to now on producing composites based on nickel free stainless steel and hydroxyapatite and study of their tribology. The aim of this work was to produce novel biocomposites made up of nickel free stainless steel with hydroxyapatite (prepared by heat treating bone ash) and studying their tribology under various loads in air and in Ringer's physiological solution. Different amounts of hydroxyapatite powder (10, 20, 30 and 40% Vol.) were added to this nickel free stainless steel powder to get the biocomposites. Variation of their density, hardness, wear resistance and friction with the ceramic (hydroxyapatite) content and wear load were investigated in air and in Ringer's solution. The density of the composites was decreased by increasing the volume percentage of the hydroxyapatite, while wear resistance of the composites was increased. The wear mechanism of these composites was changed by increasing the wear load and consequently the volume loss was enhanced dramatically. Furthermore, by increasing the sliding distance, the rate of volume loss was decreased slightly. The friction coefficient of the composites was also decreased by increasing the weight percentage of hydroxyapatite. Effect of the physiological Ringer's solution on wear resistance and friction coefficient of the composites was nearly negligible. The wear mechanisms of the samples were identified by studying the SEM images of the worn surfaces of the tested samples in different wear loads and HA contents. PMID:20129417

  6. 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.

  7. Hydroxyapatite electrodeposition on anodized titanium nanotubes for orthopedic applications

    NASA Astrophysics Data System (ADS)

    Parcharoen, Yardnapar; Kajitvichyanukul, Puangrat; Sirivisoot, Sirinrath; Termsuksawad, Preecha

    2014-08-01

    Nanotubes modification for orthopedic implants has shown interesting biological performances (such as improving cell adhesion, cell differentiation, and enhancing osseointegration). The purpose of this study is to investigate effect of titanium dioxide (TiO2) nanotube feature on performance of hydroxyapatite-coated titanium (Ti) bone implants. TiO2 nanotubes were prepared by anodization using ammonium fluoride electrolyte (NH4F) with and without modifiers (PEG400 and Glycerol) at various potential forms, and times. After anodization, the nanotubes were subsequently annealed. TiO2 nanotubes were characterized by scanning electron microscope and X-ray diffractometer. The amorphous to anatase transformation due to annealing was observed. Smooth and highly organized TiO2 nanotubes were found when high viscous electrolyte, NH4F in glycerol, was used. Negative voltage (-4 V) during anodization was confirmed to increase nanotube thickness. Length of the TiO2 nanotubes was significantly increased by times. The TiO2 nanotube was electrodeposited with hydroxyapatite (HA) and its adhesion was estimated by adhesive tape test. The result showed that nanotubes with the tube length of 560 nm showed excellent adhesion. The coated HA were tested for biological test by live/dead cell straining. HA coated on TiO2 nanotubes showed higher cells density, higher live cells, and more spreading of MC3T3-E1 cells than that growing on titanium plate surface.

  8. Intrinsic magnetism and hyperthermia in bioactive Fe-doped hydroxyapatite.

    PubMed

    Tampieri, Anna; D'Alessandro, Teresa; Sandri, Monica; Sprio, Simone; Landi, Elena; Bertinetti, Luca; Panseri, Silvia; Pepponi, Giancarlo; Goettlicher, Joerg; Bañobre-López, Manuel; Rivas, Jose

    2012-02-01

    The use of magnetic activation has been proposed to answer the growing need for assisted bone and vascular remodeling during template/scaffold regeneration. With this in mind, a synthesis procedure was developed to prepare bioactive (Fe2+/Fe3+)-doped hydroxyapatite (Fe-HA), endowed with superparamagnetic-like properties. This new class of magnetic hydroxyapatites can be potentially employed to develop new magnetic ceramic scaffolds with enhanced regenerative properties for bone surgery; in addition, magnetic Fe-HA can find application in anticancer therapies, to replace the widely used magnetic iron oxide nanoparticles, whose long-term cytotoxicity was recently found to reach harmful levels. An extensive physicochemical, microstructural and magnetic characterization was performed on the obtained Fe-HA powders, and demonstrated that the simultaneous addition of Fe2+ and Fe3+ ions during apatite nucleation under controlled synthesis conditions induces intrinsic magnetization in the final product, minimizing the formation of magnetite as secondary phase. This result potentially opens new perspectives for biodevices aimed at bone regeneration and for anti-cancer therapies based on hyperthermia. PMID:22005331

  9. 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. PMID:7662828

  10. Surface characteristics of a novel hydroxyapatite-coated dental implant

    PubMed Central

    Jung, Ui-Won; Hwang, Ji-Wan; Choi, Da-Yae; Hu, Kyung-Seok; Kwon, Mi-Kyung; Choi, Seong-Ho

    2012-01-01

    Purpose This study evaluated the surface characteristics and bond strength produced using a novel technique for coating hydroxyapatite (HA) onto titanium implants. Methods HA was coated on the titanium implant surface using a super-high-speed (SHS) blasting method with highly purified HA. The coating was performed at a low temperature, unlike conventional HA coating methods. Coating thickness was measured. The novel HA-coated disc was fabricated. X-ray diffraction analysis was performed directly on the disc to evaluate crystallinity. Four novel HA-coated discs and four resorbable blast medium (RBM) discs were prepared. Their surface roughnesses and areas were measured. Five puretitanium, RBM-treated, and novel HA-coated discs were prepared. Contact angle was measured. Two-way analysis of variance and the post-hoc Scheffe's test were used to analyze differences between the groups, with those with a probability of P<0.05 considered to be statistically significant. To evaluate exfoliation of the coating layer, 7 sites on the mandibles from 7 mongrel dogs were used. Other sites were used for another research project. In total, seven novel HA-coated implants were placed 2 months after extraction of premolars according to the manufacturer's instructions. The dogs were sacrificed 8 weeks after implant surgery. Implants were removed using a ratchet driver. The surface of the retrieved implants was evaluated microscopically. Results A uniform HA coating layer was formed on the titanium implants with no deformation of the RBM titanium surface microtexture when an SHS blasting method was used. Conclusions These HA-coated implants exhibited increased roughness, crystallinity, and wettability when compared with RBM implants. PMID:22586524

  11. 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.

  12. 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. PMID:27157760

  13. 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. PMID:19083081

  14. Comparative evaluation of biocompatibility of dense nanostructured and microstructured Hydroxyapatite/Titania composites.

    PubMed

    Farzin, A; Ahmadian, M; Fathi, M H

    2013-05-01

    This work deals with the biocompatibility of dense nano- and micro-structured Hydroxyapatite/Titania composites prepared by two step and conventional sintering, respectively. By application of two step sintering, it was shown that the final grain size of HA-15 wt.% TiO2 is maintained lower than 100 nm while by the application of conventional sintering it reaches higher than 100 nm. Biocompatibility of the dense bulks was evaluated by cell attachment and proliferation experiments. Cell morphology, and viability on each nano- and micro-structured Hydroxyapatite/Titania composites were examined at different time points. The nanostructured HA/Titania dense bulk exhibited higher cell viability than a microstructured one. In addition, the effects of ionic products from nano- and micro-structured bulk dissolution on osteoblasts were studied. The MTT test confirmed that the products from nanostructured HA/Titania dense bulk significantly promoted osteoblast proliferation within a certain concentration range. PMID:23498255

  15. Converting ultrasonic induction heating deposited monetite coating to Na-doped HA coating on H 2O 2-treated C/C composites by a two-step hydrothermal method

    NASA Astrophysics Data System (ADS)

    Xin-bo, Xiong; Jian-feng, Hung; Xie-rong, Zeng; Cen-cen, Chu

    2011-10-01

    a monetite coating on H 2O 2-treated C/C composites was prepared by ultrasonic induction heating (UIH) technology. Subsequently, this coating was subjected to an ammonia hydrothermal treatment to form a undoped hydroxyapatite (U-HA) coating. Finally, the as-prepared U-HA coating was placed in a NaOH solution and hydrothermally treated to produce the other hydroxyapatite (Na-HA) coating. The structure, morphology and chemical composition of the two HA coatings were characterized by XRD, FTIR, SEM and EDS, the adhesiveness and local mechanical properties, e.g. nanohardness and Young's modulus of the two HA coatings to C/C composites was evaluated by a scratch test and nanoindentation technique respectively. The results showed that the two HA coatings had the alike morphology and crystallization. But, compared with the U-HA coating, the Na-HA coating was doped with Na ions, and gave a Ca/P ratio close to a stoichiometric hydroxyapatite, and thus showed a higher nano-indentation value, Young's modulus, and larger bonding strength. These results verified the strengthened effect of Na ion in hydroxyapatite coating on carbon/carbon (C/C) composities.

  16. Effects of strontium ions on growth and dissolution of hydroxyapatite and on bone mineral detection.

    PubMed

    Christoffersen, J; Christoffersen, M R; Kolthoff, N; Bärenholdt, O

    1997-01-01

    Preparation and analyses of a series of hydroxyapatites (HA) containing 1-10 mol % of Ca2+ replaced by Sr2+ is reported. The solubility of these apatites is found to increase with increasing content of Sr2+, 10% SrHA dissolves faster than CaHA at given values of Ca2+ and phosphate concentrations, but with a similar rate at the same degree of saturation. Sr2+ is found to inhibit the rates of both dissolution and growth of CaHA and 10% SrHA at pH 7.2, CaHA being more strongly inhibited by Sr2+ than 10% SrHA. The effect of partial substitution of Ca2+ in hydroxyapatite by Sr2+ on bone mineral content (BMC) and bone mineral density (BMD) measured by dual energy X-ray absorptiometry has been studied using three commercial densitometers. Extrapolating the absorption data for up to 10% replacement of Ca2+ by Sr2+ to 100% substitution of Ca2+ by Sr2+ in HA leads to an apparent increase in BMC or BMD of about a factor of 10. This factor is in agreement with theoretical calculations using attenuation coefficients of the atoms concerned. It is concluded that existing BMC scanners register artificially high values of BMC if the bone contains significant amounts of Sr2+ or other metal ions with atomic number larger than calcium. PMID:8988347

  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. Differential effects of different forms of hydroxyapatite and hydroxyapatite/tricalcium phosphate particulates on human monocyte/macrophages in vitro.

    PubMed

    Harada, Y; Wang, J T; Doppalapudi, V A; Willis, A A; Jasty, M; Harris, W H; Nagase, M; Goldring, S R

    1996-05-01

    A possible complication associated with the use of hydroxyapatite (HA) or HA/tricalcium phosphate (HA/TCP) coating on the surfaces of prosthetic devices used for dental and orthopedic implants is their potential to fragment and thus exist as wear debris. In contrast to the so-called osteoconductive properties of HA or HA/TCP coatings, in particulate form these materials may lead to an adverse pattern of cellular and tissue responses at the bone-implant interface. We have established an in vitro cell culture system to characterize the biologic and biochemical effects of various particulate materials. The present study demonstrates that the HA/TCP particles derived from different sintering temperatures exhibit differential effects on cultured human monocyte/macrophages (M/M). The HA/TCP particles dried at 110 degrees C were the most biologically active, stimulating significant release of interleukin 1 beta (IL-1 beta), IL-6, tumor necrosis factor alpha, and prostaglandin E2 (PGE2), products implicated as important mediators of inflammation in diverse pathologic conditions. Other particles, sintered at either 900 or 1200 degrees C, did not stimulate production of cytokines or PGE2. HA/TCP particles from plasma-spray coatings also failed to release proinflammatory products. These results suggest that the biochemical and crystalline structural properties of particles markedly affects their capacity to modulate M/M function. This in vitro culture system should be useful in characterizing the specific physical and chemical properties of HA or HA/TCP particulates that are responsible for stimulating proinflammatory cell responses. PMID:8731145

  20. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-?-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 ?m), 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-?-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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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. PMID:19627776

  6. Microspheres and their methods of preparation

    SciTech Connect

    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.

  7. Inhibition of hydroxyapatite formation by osteopontin phosphopeptides.

    PubMed Central

    Pampena, David A; Robertson, Karen A; Litvinova, Olga; Lajoie, Gilles; Goldberg, Harvey A; Hunter, Graeme K

    2004-01-01

    Osteopontin (OPN) is an acidic phosphoglycoprotein that is believed to function in the prevention of soft tissue calcification. In vitro studies have shown that OPN can inhibit the formation of hydroxyapatite (HA) and other biologically relevant crystal phases, and that this inhibitory activity requires phosphorylation of the protein; however, it is not known which phosphorylated residues are involved. We have synthesized peptides corresponding to four phosphoserine-containing sequences in rat OPN: OPN7-17, containing phosphoserines 10 and 11; OPN41-52, containing phosphoserines 46 and 47; OPN248-264, containing phosphoserines 250, 257 and 262; and OPN290-301, containing phosphoserines 295-297. The abilities of these peptides to inhibit de novo HA formation were determined using a constant-composition autotitration assay. All four OPN phosphopeptides caused a dose-dependent increase in nucleation lag time, but did not significantly affect subsequent formation of the crystals. However, OPN41-52 (inhibitory constant 73.5 min/microM) and OPN290-301 (72.2 min/microM) were approx. 4 times more potent inhibitors than OPN7-17 (19.7 min/microM) and OPN247-264 (16.3 min/microM). 'Scrambling' the amino acid sequence of OPN290-301 resulted in decreased potency (45.6 min/microM), whereas omission of the phosphate groups from this peptide caused a greater decrease (5.20 min/microM). These findings have identified phosphorylated sequences that are important for the ability of rat bone OPN to inhibit HA crystal formation, and suggest that negative-charge density is an important factor in this activity. PMID:14678013

  8. Calcium Deficient Hydroxyapatite for Medical Application Prepared by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Ioku, Koji; Kamitakahara, Masanobu; Ikeda, Tohru

    2010-11-01

    Hydrothermal processing plays a key role in the synthesis of biomaterials with excellent biocompatibility in the physiological environment. Especially, calcium phosphates are paid to much attention for the regenerative medicine. Two kinds of porous materials of hydroxyapatite with 70% porosity were prepared. One of them is a newly developed calcium-deficient hydroxyapatite composed of rod-shaped particles of about 20 μm in length synthesized hydrothermally (HHA) and the other one is the stoichiometric hydroxyapatite (SHA) prepared by the conventional sintering method. These materials were used for animal implantation tests to compare these biological responses. In the rabbit femur, implanted HHA was slowly resorbed and then most of the implanted HHA was resorbed after 72 weeks. The implanted SHA was unresorbed throughout the experimental period. The volume of newly formed bone and the number of osteoclasts in the implanted region were significantly larger in HHA than in SHA after 24 weeks. Results in the present research suggested that the activity of osteoclasts correlated to the bone forming activity of osteoblasts. The method to synthesize biodegradable pure calcium-deficient HA is expected to provide adequate biodegradability and bone replaceability.

  9. Synthesis of fluorapatite-hydroxyapatite nanoparticles and toxicity investigations.

    PubMed

    Montazeri, N; Jahandideh, R; Biazar, Esmaeil

    2011-01-01

    In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatible and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. PMID:21499417

  10. Synthesis of fluorapatite–hydroxyapatite nanoparticles and toxicity investigations

    PubMed Central

    Montazeri, N; Jahandideh, R; Biazar, Esmaeil

    2011-01-01

    In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca10(PO4)6F2) and hydroxyapatite (HA; Ca10(PO4)6(OH)2), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatibile and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. PMID:21499417

  11. Formation and Characterization of Crystalline Hydroxyapatite Coating with the (002) Texture

    NASA Astrophysics Data System (ADS)

    Grubova, I.; Priamushko, T.; Chudinova, E.; Surmeneva, M.; Korneva, O.; Epple, M.; Prymak, O.; Shulepov, I.; Surmenev, R.

    2016-02-01

    This study reports the effect of titanium (Ti) microstructure on the mechanical properties and surface wettability of thin (<800 nm) hydroxyapatite (HA) coating deposited via radio-frequency (RF) magnetron sputtering. It was revealed that the sand-blasting (SB) and acid etching (AE) of Ti prior deposition led to a wide range of surface roughness in nano/micro scale. After nanostructured HA coating deposition such physico-mechanical characteristics as nanohardness H, Young's modulus E, H/E ratio and H3/E2 were significantly improved. Moreover, HA coatings exhibited improved wear resistance, lower friction coefficient and ability of the coating to wetting.

  12. Characterization of Hydroxyapatite-Glass Composites Using Terahertz Time-Domain Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yatongchai, C.; Wren, A. W.; Sundaram, S. K.

    2015-01-01

    Terahertz time-domain spectroscopy (THz-TDS) is presented as a tool for characterization of the hydroxyapatite (HA)-glass composites. The materials under investigation are composites of HA and a calcium zinc silicate glass. Our results show that the refractive index and dielectric constant in THz frequencies provide a reliable determination of glass content of these composites. In addition, the THz-TDS is used to morphological changes in HA during simulated body fluid (SBF) incubation. Our results demonstrate that the THz-TDS can be a promising non-destructive tool.

  13. Characterization of Hydroxyapatite-Glass Composites Using Terahertz Time-Domain Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yatongchai, C.; Wren, A. W.; Sundaram, S. K.

    2014-08-01

    Terahertz time-domain spectroscopy (THz-TDS) is presented as a tool for characterization of the hydroxyapatite (HA)-glass composites. The materials under investigation are composites of HA and a calcium zinc silicate glass. Our results show that the refractive index and dielectric constant in THz frequencies provide a reliable determination of glass content of these composites. In addition, the THz-TDS is used to morphological changes in HA during simulated body fluid (SBF) incubation. Our results demonstrate that the THz-TDS can be a promising non-destructive tool.

  14. 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.

  15. [Atrophy of the tympanic membrane in contact with hydroxyapatite prosthesis: physiopathologic approach].

    TOXLINE Toxicology Bibliographic Information

    Ramírez Camacho R; Pinilla Urraca M; García Berrocal JR; Vallet-Regí M

    2001-01-01

    The implantation of ossicular replacement prothesis made of dense hydroxyapatite (HA) appears to be a wider method of reconstruction of ossicular chain damaged by suppurative processes or surgery. A review of 19 patients who underwent implantation of HA prosthesis disclosed 4 cases of extrusion and 3 cases of atrophy. When X-ray diffraction analysis of explanted commercially available prosthesis made of dense HA was compared with the results with porous implants and with HS powder employed in the manufacture of both, is suggested that tympanic membrane atrophy could be caused by mechanical and/or chemical factors.

  16. Advances in Microsphere Insulation Systems

    NASA Astrophysics Data System (ADS)

    Allen, M. S.; Baumgartner, R. G.; Fesmire, J. E.; Augustynowicz, S. D.

    2004-06-01

    Microsphere insulation, typically consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. Microspheres provide robust, low-maintenance insulation systems for cryogenic transfer lines and dewars. They also do not suffer from compaction problems typical of perlite that result in the necessity to reinsulate dewars because of degraded thermal performance and potential damage to its support system. Since microspheres are load bearing, autonomous insulation panels enveloped with lightweight vacuum-barrier materials can be created. Comprehensive testing performed at the Cryogenics Test Laboratory located at the NASA Kennedy Space Center demonstrated competitive thermal performance with other bulk materials. Test conditions were representative of actual-use conditions and included cold vacuum pressure ranging from high vacuum to no vacuum and compression loads from 0 to 20 psi. While microspheres have been recognized as a legitimate insulation material for decades, actual implementation has not been pursued. Innovative microsphere insulation system configurations and applications are evaluated.

  17. Photocatalytic Deposition of Hydroxyapatite onto a Titanium Dioxide Nanotubular Layer with Fine Tuning of Layer Nanoarchitecture.

    PubMed

    Ulasevich, Sviatlana A; Poznyak, Sergey K; Kulak, Anatoly I; Lisenkov, Aleksey D; Starykevich, Maksim; Skorb, Ekaterina V

    2016-04-26

    A new effective method of photocatalytic deposition of hydroxyapatite (HA) onto semiconductor substrates is proposed. A highly ordered nanotubular TiO2 (TNT) layer formed on titanium via its anodization is chosen as the photoactive substrate. The method is based on photodecomposition of the phosphate anion precursor, triethylphosphate (TEP), on the semiconductor surface with the following reaction of formed phosphate anions with calcium cations presented in the solution. HA can be deposited only on irradiated areas, providing the possibility of photoresist-free HA patterning. It is shown that HA deposition can be controlled via pH, light intensity, and duration of the process. Energy-dispersive X-ray spectroscopy profile analysis and glow discharge optical emission spectroscopy of HA-modified TNT prove that HA deposits over the entire TNT depth. High biocompatibility of the surfaces is proven by protein adsorption and pre-osteoblast cell growth. PMID:26991479

  18. 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.

  19. Synthesis of silver-incorporated hydroxyapatite nanocomposites for antimicrobial implant coatings

    NASA Astrophysics Data System (ADS)

    Liu, Xiangmei; Mou, Yanan; Wu, Shuilin; Man, H. C.

    2013-05-01

    Because of excellent osteoconductivity and resorbability, hydroxyapatite (HA) is commonly used as a bone substitute material or implant coating. Both ionic and metallic silver are considered to have a broad spectrum of antimicrobial properties especially associated with biomaterial-related infections. The present work proposes a facile chemical reduction method to synthesize an Ag incorporated HA nanocomposite. Ammoniacal silver solution was firstly prepared and then added into the HA solution, followed by hydrazine hydrate (N2H4·H2O) being used to reduce the silver ions to metallic silver. The formed Ag nanoparticles had diameters of 20-30 nm and were firmly attached on the HA particle surfaces. This approach can also keep the integrity of the HA chemical structure and the morphology. The strain Escherichia coli was used to evaluate the antibacterial effect of the nanocomposite. An In vitro bacterial adhesion study indicated a significant enhancement in the antibacterial property of silver containing HA.

  20. 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. PMID:25125978

  1. 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

  2. Hydrothermal fabrication of hydroxyapatite on the PEG-grafted surface of wood from Chinese Glossy Privet

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Cai, Chuanjie; Cai, Dongqing; Cheng, Junjie; Li, Shengli; Wu, Zhengyan

    2012-10-01

    Wood-hydroxyapatite composite material was developed by depositing hydrated calcium hydrogen phosphate (HCHP) on the surface of wood from Chinese Glossy Privet (CGP) with polyethylene glycol (PEG, HO(CH2CH2O)nH) as the grafting agent and subsequent hydrothermal vapor treatment. The results illustrated that HCHP could adhere quickly and strongly on the PEG-grafted wood surface. Moreover, this HCHP could be efficiently transformed to hydroxyapatite (HA, Ca10(PO4)6(OH)2) by hydrothermal vapor treatment. IR, XRD analysis and SEM observation indicated that the fabricated hydroxyapatite was pure and its morphology was uniform and microporous. This work provides a new fabricating approach of biocompatible material which may have some potential applications as bone-repairing material.

  3. Elaboration of the hydroxyapatite with different precursors and application for the retention of the lead.

    PubMed

    Meski, S; Ziani, S; Khireddine, H; Yataghane, F; Ferguene, N

    2011-01-01

    Carbonate hydroxyapatite (CHAP) was synthesized from different precursors; synthetic (CaCO3 and Ca(OH)2) and natural (egg shell before and after calcinations at 900 degrees C) under different conditions and characterized by using TG/DTG analysis, X-ray powder diffraction (XRD) method and Fourier transform infrared (FT-IR) spectroscopy techniques. The results of these analyses indicate that the four powders present the same structure of hydroxyapatite. Furthermore the four powders obtained were used for the retention of lead. The results obtained indicated that all powders present high adsorption capacity for lead, but from environmental and economic views, the hydroxyapatite synthesized from eggshell no calcined (HA2) is most advantageous. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and sorbent dosage was studied and discussed. PMID:21977625

  4. Preliminary report on the biocompatibility of a moldable, resorbable, composite bone graft consisting of calcium phosphate cement and poly(lactide-co-glycolide) microspheres.

    PubMed

    Simon, Carl G; Khatri, Chetan A; Wight, Scott A; Wang, Francis W

    2002-05-01

    We have assessed the biocompatibility of a new composite bone graft consisting of calcium phosphate cement (CPC) and poly(lactide-co-glycolide) (PLGA) microspheres (approximate diameter of 0.18-0.36 mm) using cell culture techniques. CPC powder is mixed with PLGA microspheres and water to yield a workable paste that could be sculpted to fit the contours of a wound. The cement then hardens into a matrix of hydroxyapatite microcrystals containing PLGA microspheres. The rationale for this design is that the microspheres will initially stabilize the graft but can then degrade to leave behind macropores for colonization by osteoblasts. The CPC matrix could then be resorbed and replaced with new bone. In the present study, osteoblast-like cells (MC3T3-E1 cells) were seeded onto graft specimens and evaluated with fluorescence microscopy, environmental scanning electron microscopy and the Wst-1 assay (an enzymatic assay for mitochondrial dehydrogenase activity). Cells were able to adhere, attain a normal morphology, proliferate and remain viable when cultured on the new composite graft (CPC-PLGA) or on a control graft (CPC alone). These results suggest that our new cement consisting of CPC and PLGA microspheres is biocompatible. This is the first time that a 'polymer-in-mineral' (PLGA microspheres dispersed in a CPC matrix) cement has been formulated that is moldable, resorbable and that can form macropores after the cement has set. PMID:12038620

  5. A new approach for the one-step synthesis of bioactive PS vs. PMMA silica hybrid microspheres as potential drug delivery systems.

    PubMed

    Angelopoulou, A; Efthimiadou, E K; Boukos, N; Kordas, G

    2014-05-01

    In this work, hybrid microspheres were prepared in a two-step process combining the emulsifier free-emulsion polymerization and the sol-gel coating method. In the first step, polystyrene (St) and poly(methyl methacrylate) (PMMA) microspheres were prepared as sacrificial template and in the second step a silanol shell was fabricated. The functionalized surface of the hybrid microspheres by silane analogs (APTES, TEOS) resulted in enhanced effects. The hollow microspheres were resulted either in an additional step by template dissolution and/or during the coating process. The microspheres' surface interactions and the size distribution were optimized by treatment in simulated body fluids, which resulted in the in vitro prediction of bioactivity. The bioassay test indicated that the induced hydroxyapatite resembled in structure to naturally occurring bone apatite. The drug doxorubicin (DOX) was used as a model entity for the evaluation of drug loading and release. The drug release study was performed in two different pH conditions, at acidic (pH=4.5) close to cancer cell environment and at slightly basic pH (pH=7.4) resembling the orthopedic environment. The results of the present study indicated promising hybrid microspheres for the potential application as drug delivery vehicles, for dual orthopedic functionalities in bone defects, bone inflammation, bone cancer and bone repair. PMID:24670261

  6. In vitro study on the degradation of lithium-doped hydroxyapatite for bone tissue engineering scaffold.

    PubMed

    Wang, Yaping; Yang, Xu; Gu, Zhipeng; Qin, Huanhuan; Li, Li; Liu, Jingwang; Yu, Xixun

    2016-09-01

    Li-doped hydroxyapatite (LiHA) which is prepared through introducing low dose of Li into hydroxyapatite (HA) has been increasingly studied as a bone tissue-engineered scaffold. The degradation properties play a crucial role in the success of long-term implantation of a bone tissue-engineered construct. Herein, the in vitro degradation behaviors of LiHA scaffolds via two approaches were investigated in this study: solution-mediated degradation and osteoblast-mediated degradation. In solution-mediated degradation, after being immersed in simulated body fluid (SBF) for some time, some characteristics of these scaffolds (such as release of ionized lithium and phosphate, pH change, mechanical properties, cytocompatibility and SEM surface characterization) were systematically tested. A similar procedure was also employed to research the degradation behaviors of LiHA scaffolds in osteoblast-mediated degradation. The results suggested that the degradation in SBF and degradation in culture medium with cell existed distinguishing mechanisms. LiHA scaffolds were degraded via a hydrolytic mechanism when they were soaked in SBF. Upon degradation, an apatite precipitation (layer) was formed on the surfaces of scaffolds. While a biological mechanism was presented for the degradation of scaffolds in cell-mediated degradation. Compared with pure HA, LiHA scaffolds had a better effect on the growth of osteoblast cells, meanwhile, the release amount of PO4(3-) in a degradation medium indicated that osteoblasts could accelerate the degradation of LiHA due to the more physiological activities of osteoblast. According to the results from compressive strength test, doping Li into HA could enhance the strength of HA. Moreover, the results from MTT assay and SEM observation showed that the degradation products of LiHA scaffolds were beneficial to the proliferation of osteoblasts. The results of this research can provide the theoretical basis for the clinical application of LiHA scaffolds. PMID:27207053

  7. 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.

  8. 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. PMID:23281190

  9. 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.

  10. 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. PMID:19349655

  11. Zn and Mg Doped Hydroxyapatite Nanoparticles for Controlled Release of Protein

    PubMed Central

    Dasgupta, Sudip; Bandyopadhyay, Amit; Bose, Susmita

    2010-01-01

    Bovine serum albumin (BSA) protein incorporated with hydroxyapatite (HA) nanoparticles (NPs) were synthesized by in situ precipitation process. 2 mol% Zn2+ and Mg2+ were used as dopants to synthesize Zn2+/Mg2+ doped HA-BSA NPs by in situ synthesis route. In our study we used BSA as a model protein. The amount of BSA uptake by doped and undoped HA NPs and subsequent release of BSA from NPs were investigated. Zn doped HA NPs showed the highest amount of BSA uptake, whereas the amount of BSA loaded in undoped HA NPs was the lowest. A two-stage BSA release profile from doped and undoped HA NPs was observed in phosphate buffer solution (PBS) at pH 7.2 0.2. Initial burst release was due to the desorption of BSA from the HA surface. The later stage of slow release was controlled by the dissolution of BSA incorporated HA NPs. BSA release rate from Zn doped HA NPs was found to be the highest, whereas undoped HA NPs released BSA at the slowest rate. Our study showed that the protein release rate from HA NPs can be controlled by the addition of suitable dopants and doped HA based NP systems can be used in bone growth factor and drug release study. PMID:20131882

  12. [The role of synthetic hydroxyapatite solution in the destructive process of arteriosclerosis].

    PubMed

    Lipnicka, Patrycja; Pawlikowski, Maciej; Pfttzner, Roman

    2003-01-01

    Presented work is a pilot research on dissolving of homogeneous synthetic hydroxyapatite, being chemically analogous to the hydroxyapatite formed in human organism. Crystallization of hydroxyapatite (HA) in human arteries also known as calcification is a complex process leading to dysfunctions in the functioning of human blood system and--in effect--to dysfunction in functioning of tissues and organs [1]. Mineralization of blood vessels is a complicated process and can appear in two forms: visible and hidden, which can be organic or inorganic [2]. With inorganic mineralization there are concerned primarily phosphoranes of Calcium, mostly apathites, while the organic mineralization is represented by organic substances like cholesterol, fats, lipids [2, 3]. The forming of crystals, fats, lipids etc. in arteries is an effect of continuation of the processes started by hidden mineralization [1]. Research was focused on the possibilities of dissolving the visible, inorganic mineralization, represented by synthetic hydroxyapatite. In the work, there are presented preliminary results of biochemical studies on dissolving of the synthetic hydroxyapatite. The processes of dissolving of this compound took place in dynamic conditions. The organic solutions of hawthorn, onion and garlic of various concentrations--2.5%, 5%, 7.5%--were used as the solvents. These herbs show anti-calcification effects. The preliminary results of the experiments confirm the hypothesis that the solutions of these herbs free the Ca and P ions from the grains of synthetic HA (in varying flowing pH and speed conditions). This research encourages further analysis of the processes of dissolving hydroxyapatite--either synthetic or coming from human body. PMID:15232901

  13. 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.

  14. Chitosan based hydrogel microspheres as drug carriers.

    PubMed

    Vodn, Lucia; Bubenkov, Silvia; Lack, Igor; Chorvt, Dusan; Bakos, Dusan

    2007-05-10

    Chitosan/tripolyphosphate (CHIT/TPP) and chitosan/tripolyphosphate/chondroitin sulfate (CHIT/TPP/CHS) core-shell type microspheres were prepared by polyelectrolyte complexation in order to develop a biocompatible matrix for drug delivery. The continual method using a multi-loop reactor under sterile conditions was applied for microsphere preparation. All the types of microspheres produced were spherical in shape and had a porous structure. The mechanical resistance of the microspheres increased in the presence of CHS as the second polyanion, which toughened the microsphere shell structure. For a drug release application, the process of microsphere preparation was modified by dissolving ofloxacin (OFL), the fluoroquinolone antibiotic, in CHIT solution before complex formation. This study shows the difference in OFL release comparing the microspheres CHIT/TPP and CHIT/TPP/CHS and implies the potential to control this process. PMID:17477445

  15. Hydroxyapatite ceramics from hydrothermally prepared powders

    SciTech Connect

    Lin, C.H.; Huang, C.W.; Chang, S.C.

    1994-12-31

    Hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}(OH)) is an effective material for artificial human bone production. Hydroxyapatite powders were hydrothermally produced in this work by reacting Ca(OH){sub 2} with Na{sub 3}PO{sub 4}{center_dot}12H{sub 2}O in an autoclave at various temperature and for various times. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 nm, as well as independent of reaction time. The hydroxyapatite powders were compacted and sintered at various temperatures for 2 hrs. The density, grain size, and hardness of the hydroxyapatite ceramics were measured and compared with those of the hydroxyapatite ceramics produced by the powders from the commercial source. The hydroxyapatite ceramics from the hydrothermal powders were found to have a higher density, smaller grain size, and higher hardness. After the hydroxyapatite ceramics were dipped in a simulated biological body liquid for 10 days, the density and hardness of the hydroxyapatite ceramics from the hydrothermal powders were less deteriorated than those of the hydroxyapatite ceramics from the commercial powder.

  16. 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). 80wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10wt.% CHX and 0, 10, 20 or 40wt.% 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 4weeks. XRD peak width and SEM images suggested this was due to the very small size (~10nm) of the hydroxyapatite crystallites. Precipitate mass at 12weeks was 22wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7wt.% 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 1week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12weeks CHX formed 5 to 15% of the HA layer with 10 to 40wt.% CaP respectively. Despite linear decline of strength and modulus in 4weeks from 160 to 101MPa and 4 to 2.4GPa, 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. PMID:26706532

  17. 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.

  18. 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. PMID:27083834

  19. Hydroxyapatite-poly(L-lactide) nanohybrids via surface-initiated ATRP for improving bone-like apatite-formation abilities

    NASA Astrophysics Data System (ADS)

    He, Jiqing; Yang, Xiaoping; Mao, Jiaofu; Xu, Fujian; Cai, Qing

    2012-07-01

    It is important to improve the compatibility of hydroxyapatite (HA) nanoparticles in biodegradable polyesters to obtain desirable nanocomposites for bone tissue engineering applications. Polymer grafting has been proven an efficient way to get nanohybrids with good dispersibility in polymeric matrixes. In this paper, a new strategy to prepare HA-poly(L-lactide) (PLLA) nanohybrids was developed, where PLLA oligomers were grafted from HA nanoparticle surfaces via surface-initiated atom transfer radical polymerization (ATRP) of methylacrylate group terminated PLLA macromonomers (PLLA-MA). HA with the derived ATRP initiators was obtained by (1) preparation of HA from precursors in the presence of 3-aminopropyl-triethoxysilane (APTS) to produce the HA surface with terminal sbnd NH2 groups (HA-NH2) and (2) reaction of the sbnd NH2 groups of the HA-NH2 nanoparticles with 2-bromoisobutyryl bromide (BIBB) to produce the 2-bromoisobutyryl-immobilized nanoparticles (HA-Br). The obtained HA-PLLA nanohybrids demonstrated good dispersibility in chloroform. With the good dispersion of HA-PLLA nanohybrids in PLLA matrix, the resultant PLLA/HA-PLLA nanocomposites could much faster induce bone-like apatite-formation in simulated body fluids (SBF) than the PLLA/HA counterparts where the HA nanoparticles aggregated heavily. With the versatility of ATRP, properly, grafting oligomeric PLLA chains from HA nanoparticle surfaces is an effective means for the design of novel HA-polymer biohybrids for future bone tissue engineering applications.

  20. 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 by electron microprobe analysis. Both ammonia-nitrided samples and ion-implanted samples were used as substrates for bone morphogenetic proteins (BMPs) in biological studies. Nitrided hydroxyapatite samples with BMPs showed an increase in bone formation when surgically implanted in rats. Furthermore, the bone formation increased with increasing nitrogen. On the other hand, bone formation decreased with increasing nitrogen for nitrided HA samples without BMPs.

  1. 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

  2. The influence of silanisation on the mechanical and degradation behaviour of PLGA/HA composites.

    PubMed

    Naik, Ashutosh; Best, Serena M; Cameron, Ruth E

    2015-03-01

    This study investigates the influence of silanisation on the mechanical and degradation behaviour of PLGA/HA composites. Three different silanes (mercaptopropyl trimethoxy silane (MPTMS), aminopropyl trimethoxy silane (APTMS) and aminopropyltriethoxy silane (APTES)) were applied to HA substrates in order to study the effect of head group (which binds to the polymer) and tail group (which binds to the surface hydroxyl groups in HA). A composite of hydroxyapatite (HA) and poly(d,l lactide-co-glycolide (50:50)) (PLGA) was investigated. The influence of concentration, the reaction time, drying temperature and substrate surface on silanisation was examined. TGA was used to detect the degree of silanisation. HA with MPTMS (1wt.% MPTMS with reaction time of 1h) was used as filler in PLGA-30wt.% HA composites for an in-vitro degradation study carried out in PBS. In addition, the mechanical properties of the composites were studied. Silanisation affects the properties of the composite by improving the bonding at the interface and hence it was found to influence the plastic mechanical properties rather than the elastic mechanical properties or the degradation profile of the composite. PMID:25579967

  3. Comparison of microstructures and phase compositions of artificial and bone-derived hydroxyapatites by transmission electron microscopy and energy dispersive electron spectroscopy.

    PubMed

    Lee, Jong Kook

    2014-11-01

    Biological problems associated with sintered implants fabricated from artificially synthesized hydroxyapatite include selective dissolution at grain boundaries, microstructural disintegration in the body due to particle loosening, and slow crack growth at the implant surface. In addition, mechanical degradation has been shown to be significant, thus limiting their application as load-bearing medical implants. In contrast, bone-derived hydroxyapatite bioceramics have highly dissolution-resistant properties and excellent biocompatibility in the body. They are also easy to synthesize by thermal decomposition of animal bone. In this study, microstructural observations and crystal phase analysis of bone-derived hydroxyapatite were investigated by TEM and EDS using sintered hydroxyapatite samples. In addition, a comparative investigation into elemental distributions and the microstructures of artificial hydroxyapatite, bovine, and tuna bone-derived hydroxyapatites was performed. Bone-derived HA consists mainly of HA and a small amount of MgO. Hot-pressed HA compacts showed homogeneous microstructures and densities of 95-97%, however, grain sizes and microstructures varied with the starting powders. PMID:25958617

  4. 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. PMID:26405972

  5. A new hydroxyapatite-based biocomposite for bone replacement.

    PubMed

    Bellucci, Devis; Sola, Antonella; Gazzarri, Matteo; Chiellini, Federica; Cannillo, Valeria

    2013-04-01

    Since the 1970s, various types of ceramic, glass and glass-ceramic materials have been proposed and used to replace damaged bone in many clinical applications. Among them, hydroxyapatite (HA) has been successfully employed thanks to its excellent biocompatibility. On the other hand, the bioactivity of HA and its reactivity with bone can be improved through the addition of proper amounts of bioactive glasses, thus obtaining HA-based composites. Unfortunately, high temperature treatments (1200°C÷1300°C) are usually required in order to sinter these systems, causing the bioactive glass to crystallize into a glass-ceramic and hence inhibiting the bioactivity of the resulting composite. In the present study novel HA-based composites are realized and discussed. The samples can be sintered at a relatively low temperature (800 °C), thanks to the employment of a new glass (BG_Ca) with a reduced tendency to crystallize compared to the widely used 45S5 Bioglass®. The rich glassy phase, which can be preserved during the thermal treatment, has excellent effects in terms of in vitro bioactivity; moreover, compared to composites based on 45S5 Bioglass® having the same HA/glass proportions, the samples based on BG_Ca displayed an earlier response in terms of cell proliferation. PMID:23827547

  6. Increased risk of revision of acetabular cups coated with hydroxyapatite

    PubMed Central

    Lazarinis, Stergios; Kärrholm, Johan

    2010-01-01

    Background Hydroxyapatite (HA) is the main inorganic component of bone, and HA coating is widely used on acetabular cups in hip arthroplasty. It has been suggested that this surface finish improves cup survival. Methods All patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2007 with an uncemented acetabular implant that was available either with or without HA coating were identified. 8,043 total hip arthroplasties (THAs) with the most common cup types (Harris-Galante, Romanus, and Trilogy) were investigated. A Cox regression model including type of coating, age, sex, primary diagnosis, cup type, and type of stem fixation was used to calculate adjusted risk ratios (RRs) for the risk of revision. Results HA coating was a risk factor for cup revision due to aseptic loosening (adjusted RR 1.7; 95% CI: 1.3–2). Age at primary arthroplasty of < 50 years, a diagnosis of pediatric hip disease, the use of a cemented stem, and the Romanus and Harris-Galante cup types were also associated with statistically significantly increased risk of cup revision due to aseptic loosening. Interpretation Our findings question the routine use of HA-coated cups in primary total hip arthroplasty. With some designs, this practice may even increase the risk of loosening—resulting in revision surgery. PMID:19968603

  7. 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/PLGA composite, which can accelerate the degradation PLGA 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.

  8. 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. PMID:18219555

  9. 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.

  10. 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. PMID:25390283

  11. 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.

  12. 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.

  13. Effect of Nano-HA/Collagen Composite Hydrogels on Osteogenic Behavior of Mesenchymal Stromal Cells.

    PubMed

    Hayrapetyan, Astghik; Bongio, Matilde; Leeuwenburgh, Sander C G; Jansen, John A; van den Beucken, Jeroen J J P

    2016-06-01

    This study aimed to comparatively evaluate the in vitro effect of nanosized hydroxyapatite and collagen (nHA/COL) based composite hydrogels (with different ratios of nHA and COL) on the behavior of human mesenchymal stromal cells (MSCs), isolated from either adipose tissue (AT-MSCs) or bone marrow (BM-MSCs). We hypothesized that (i) nHA/COL composite hydrogels would promote the osteogenic differentiation of MSCs in an nHA concentration dependent manner, and that (ii) AT-MSCs would show higher osteogenic potential compared to BM-MSCs, due to their earlier observed higher proliferation and osteogenic differentiation potential in 2D in vitro cultures [1]. The obtained results indicated that AT-MSCs show indeed high proliferation, differentiation and mineralization capacities in nHA/COL constructs compared to BM-MSCs, but this effect was irrespective of nHA concentration. Based on the results of alkaline phosphatase (ALP) activity and osteocalcin (OCN) protein level, the osteogenic differentiation of BM-MSCs started in the beginning of the culture period and for AT-MSCs at the end of the culture period. At a molecular level, both cell types showed high expression of osteogenic markers (bone morphogenic protein 2 [BMP2], runt-related transcription factor 2 [RUNX2], OCN or COL1) in both an nHA concentration and time dependent manner. In conclusion, AT-MSCs demonstrated higher osteogenic potential in nHA/COL based 3D micro-environments compared to BM-MSCs, in which proliferation and osteogenic differentiation were highly promoted in a time dependent manner, irrespective of nHA amount in the constructs. The fact that AT-MSCs showed high proliferation and mineralization potential is appealing for their application in future pre-clinical research as an alternative cell source for BM-MSCs. PMID:26803618

  14. HVOF-Sprayed Nano TiO2-HA Coatings Exhibiting Enhanced Biocompatibility

    NASA Astrophysics Data System (ADS)

    Lima, R. S.; Dimitrievska, S.; Bureau, M. N.; Marple, B. R.; Petit, A.; Mwale, F.; Antoniou, J.

    2010-01-01

    Biomedical thermal spray coatings produced via high-velocity oxy-fuel (HVOF) from nanostructured titania (n-TiO2) and 10 wt.% hydroxyapatite (HA) (n-TiO2-10wt.%HA) powders have been engineered as possible future alternatives to HA coatings deposited via air plasma spray (APS). This approach was chosen due to (i) the stability of TiO2 in the human body (i.e., no dissolution) and (ii) bond strength values on Ti-6Al-4V substrates more than two times higher than those of APS HA coatings. To explore the bioperformance of these novel materials and coatings, human mesenchymal stem cells (hMSCs) were cultured from 1 to 21 days on the surface of HVOF-sprayed n-TiO2 and n-TiO2-10 wt.%HA coatings. APS HA coatings and uncoated Ti-6Al-4V substrates were employed as controls. The profiles of the hMSCs were evaluated for (i) cellular proliferation, (ii) biochemical analysis of alkaline phosphatase (ALP) activity, (iii) cytoskeleton organization (fluorescent/confocal microscopy), and (iv) cell/substrate interaction via scanning electron microscopy (SEM). The biochemical analysis indicated that the hMSCs cultured on n-TiO2-10 wt.%HA coatings exhibited superior levels of bioactivity than hMSCs cultured on APS HA and pure n-TiO2 coatings. The cytoskeleton organization demonstrated a higher degree of cellular proliferation on the HVOF-sprayed n-TiO2-10wt.%HA coatings when compared to the control coatings. These results are considered promising for engineering improved performance in the next generation of thermally sprayed biomedical coatings.

  15. 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

  16. 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 nearly noncytoxic. Small molecules like Rhodamine and DHED (dehydroevodiamine HCl; Alzheimer's disease therapeutic) can be delivered along with them. Furthermore, synthesis of carbon nanoparticles and titanate nanotube species are possible utilizing these microspheres. Characterizations were done by SEM, (S)TEM, optical/confocal microscopy, XRD, XPS, EDS, SAED, zeta potential, and BET.

  17. 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

  18. Nano-hydroxyapatite/chitosan-starch nanocomposite as a novel bone construct: Synthesis and in vitro studies.

    PubMed

    Shakir, Mohammad; Jolly, Reshma; Khan, Mohd Shoeb; Iram, Noor e; Khan, Haris M

    2015-09-01

    A novel ternary nanocomposite system incorporating hydroxyapatite, chitosan and starch (n-HA/CS-ST) has been synthesized by co-precipitation method at room temperature, addressing the issues of biocompatibility, mechanical strength and cytotoxicity required for bone tissue engineering. The interactions, crystallite size, surface morphology and thermal stability against n-HA/CS nanocomposite have been obtained by comparing the results of FTIR, SEM, TEM, DLS, XRD and TGA/DTA. A comparative study of bioactivity and thermal stability of n-HA/CS and n-HA/CS-ST nanocomposites revealed that the incorporation of starch as templating agent enhanced these properties in n-HA/CS-ST nanocomposite. A lower swelling rate of n-HA/CS-ST relative to n-HA/CS indicates a higher mechanical strength supportive of bone tissue ingrowths. The MTT assay on murine fibroblast L929 and human osteoblasts-like MG-63 cells and in vitro bioactivity of n-HA/CS-ST matrix referred superior non-toxic nature of n-HA/CS-ST nanocomposite and greater possibility of osteointegration in vivo respectively. Furthermore n-HA/CS-ST exhibited improved antibacterial property against both Gram-positive and Gram-negative bacteria relative to n-HA/CS. PMID:26116779

  19. Evaluation of human osteoblastic cell response to plasma-sprayed silicon-substituted hydroxyapatite coatings over titanium substrates.

    PubMed

    Gomes, Pedro S; Botelho, Cláudia; Lopes, Maria A; Santos, José D; Fernandes, Maria H

    2010-08-01

    Silicon-substituted hydroxyapatite (Si-HA) coatings have been plasma sprayed over titanium substrates (Ti-6Al-4V) aiming to improve the bioactivity of the constructs for bone tissue repair/regeneration. X-ray diffraction analysis of the coatings has shown that, previous to the thermal deposition, no secondary phases were formed due to the incorporation of 0.8 wt % Si into HA crystal lattice. Partial decomposition of hydroxyapatite, which lead to the formation of the more soluble phases of alpha- and beta-tricalcium phosphate and calcium oxide, and increase of amorphization level only occurred following plasma spraying. Human bone marrow-derived osteoblastic cells were used to assess the in vitro biocompatibility of the constructs. Cells attached and grew well on the Si-HA coatings, putting in evidence an increased metabolic activity and alkaline phosphatase expression comparing to control, i.e., titanium substrates plasma sprayed with hydroxyapatite. Further, a trend for increased differentiation was also verified by the upregulation of osteogenesis-related genes, as well as by the augmented deposition of globular mineral deposits within established cell layers. Based on the present findings, plasma spraying of Si-HA coatings over titanium substrates demonstrates improved biological properties regarding cell proliferation and differentiation, comparing to HA coatings. This suggests that incorporation of Si into the HA lattice could enhance the biological behavior of the plasma-sprayed coating. PMID:20574971

  20. 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

  1. 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.

  2. The effect of pressure during sintering on the strength and the fracture toughness of hydroxyapatite ceramics.

    PubMed

    Kobayashi, Satoshi; Kawai, Wataru; Wakayama, Shuichi

    2006-11-01

    Hydroxyapatite (HA) is known to be biocompatible and osteoconductive, and can be synthesized chemically. The objective of the present study is to clarify the effect of pressure during sintering on the mechanical properties of HA. HA was sintered using a hot press system at a uniaxial pressure ranging from 7.81 to 62.5 MPa at a maximum temperature of 1200 degrees C with a heating rate of 10 degrees C/min. The density of the HA increased with increasing pressure and peaked at the sintering pressure of 31.2 MPa. Four-points bending tests and fracture toughness measurements with indentation method were conducted to clarify the effect of sintering pressure. Bending strength decreased at the pressure > 31.2 MPa. This result indicates that residual stress generated during sintering process became larger with increasing pressure. Fracture toughness were also lower with high density HA. PMID:17122923

  3. Preparation of hydroxyapatite-granule- implanted titanium alloy composites with a cylindrical shape.

    PubMed

    Watazu, A; Kamiya, A; Zhu, J; Shi, W; Naganuma, K; Sonoda, T; Ushiki, K; Nonami, T

    2002-02-01

    For uniformly implanting hydroxyapatite (HA) granules into curved surfaces of titanium alloy implants such as dental roots, a new superplastic forming system was developed. By fixing PVA films with HA granules on a die's curved inner surface, HA granules are uniformly scattered and hold on the surface. The pressing system has a couple of wedges that enable press load to act on the both sides of a cylindrical titanium alloy sample arranged with its long axis perpendicular to the direction of the load in the die, and thereby the sample to expand in its radius direction. This technique could uniformly press HA granules into all the curved surface of titanium alloy. As a result, HA-granule-implanted titanium alloy composites with a cylindrical shape were formed under the conditions of 1023 K, 1 h, 1960 N in vacuo. PMID:15348648

  4. 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. PMID:23882839

  5. 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.

  6. A new approach to enhancement of bone formation by electrically polarized hydroxyapatite.

    PubMed

    Teng, N C; Nakamura, S; Takagi, Y; Yamashita, Y; Ohgaki, M; Yamashita, K

    2001-10-01

    An electrical field may affect osteogenesis. Since we found that hydroxyapatite (HA) ceramics may be polarizable, we hypothesized that electrically polarized HA may foster production of new bone in vivo. Both polarized and non-polarized HA ceramics were inserted into the subperiosteum spaces at the parietal bone area of rats. After 2, 4, and 8 weeks, the implant sites were examined histologically. Morphometric analysis revealed that new bone formation was accelerated on the negatively charged surface of the polarized HA (N-surface) at 2 weeks. The newly formed bone approached maturation at 4 weeks and was thicker on the N-surface than in the controls. By 8 weeks, newly formed bone in the controls was almost the same as that on the N-surface. These findings suggest that polarized HA is biocompatible and that bone formation on the N-surface is enhanced in the early stage of bone healing. PMID:11706953

  7. Photocatalytic and Antibacterial Activity of Titanium, Fluorine and Silver Co-Substituted Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Sandhyarani, M.; Rameshbabu, N.; Venkateswarlu, K.; Ravisankar, K. V.; Ashok, M.; Anandan, S.

    Synthetic hydroxyapatite (HA), an analogue of the mineral component of bone tissue has been widely used in medicine as bone replacing material. To impart specific properties, HA can be chemically modified by anionic and cationic substitutions during synthesis. Thus the present study was focused in synthesizing nanocrystalline Ti, Ag and F co-substituted HA by microwave synthesis. The prepared powders were characterized by XRD and FTIR for their crystal size, cystallinity and functional groups respectively. XRD spectra reveal that crystal size of prepared powders was in the range of 21-25 nm in as synthesized condition and 45-51 nm in 900 ˚C heat-treated condition. Complete decomposition of HA to tri calcium phosphate was observed for Ti substituted HA powder after heat-treatment. Addition of F improved the thermal stability of Ti substituted HA as indicated by predominant phase of HA after heat-treatment. The photocatalytic activity of co-substituted HA powders was examined by degradation of methylene blue (5 × 10-5 M concentration) under visible light irradiation and the results were compared with pure HA. The degradation efficiency of co-substituted HA with respect to methylene blue was twice as high as that of pure HA. Ti and Ag has improved the visible light photocatalytic activity of HA, further F co-substitution has not affected the photocatalytic activity of substituted HA. The antibacterial effect of prepared powders was observed against 1 × 105 cells/mL of Escherichia coli using spread plate method at 24 h incubation period. Ag co-substituted HA showed complete inhibition of growth of Escherichia coli. Thus, among Ti, Ti-F, Ti-F-Ag substituted HA powders, Ti-F-Ag co-substituted HA with excellent visible light photocatalytic activity and anti-bacterial property is expected to be a potential candidate for biomedical applications.

  8. 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. PMID:25175246

  9. 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

  10. Physicochemical properties and mineralization assessment of porous polymethylmethacrylate cement loaded with hydroxyapatite in simulated body fluid.

    PubMed

    Sa, Yue; Yang, Fang; de Wijn, Joost R; Wang, Yining; Wolke, Joop G C; Jansen, John A

    2016-04-01

    The aim of this study was to evaluate the effect of carboxymethylcellulose (CMC) as a pore generator and hydroxyapatite (HA) as an osteoconductive agent on the physicochemical properties and in-vitro mineralization ability of porous polymethylmethacrylate (PMMA) cement. To this end, various compositions of PMMA cements, which differed in amount of millimeter-sized hydroxyapatite (HA) particles and CMC hydrogel, were prepared and immersed into simulated body fluid (SBF) for 0, 7, 14, 21 and 28days. It was demonstrated that the incorporation of CMC hydrogel decreased the maximum temperature of cement to the normal body temperature and prolonged the handling time during polymerization. Further, the amount of CMC was responsible for the creation of porosity and interconnectivity, which in turn determined the final mechanical properties of cements. The loaded HA particles enhanced the potential bioactivity of cement for bone ingrowth. Albeit different amount of HA particles influenced their final exposures on the surface of cured cement, all of the three amounts of HA did not weaken the final mechanical properties of cements. The data here suggests that the HA particle loaded porous PMMA cement can serve as the promising candidate for bone reconstruction. PMID:26838840

  11. 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. PMID:16701846

  12. 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. PMID:25241282

  13. In vitro osteoclast formation and resorption of silicon-substituted hydroxyapatite ceramics.

    PubMed

    Friederichs, Robert J; Brooks, Roger A; Ueda, Masato; Best, Serena M

    2015-10-01

    Materials that participate in bone remodeling at the implant/tissue interface represent a modern tissue engineering approach with the aim of balancing implant resorption and nascent tissue formation. Silicon-substituted hydroxyapatite (SiHA) ceramics are capable of stimulating new bone formation, but little is known about their interaction with osteoclasts (OC). The effects of soluble silicate and SiHA on OCs were investigated in this study. Soluble silicate below 500 μM did not stimulate cell metabolism at 4 days or alter resorption area at 7 days on calcium phosphate discs. On sintered ceramics, OC numbers were similar on HA, Si0.3 HA (0.5 wt % Si) and Si0.5 HA (1.2 wt % Si) after 21 days in vitro, but actin ring sealing zone morphology on SiHA resembled that commonly found on bone or on carbonate-substituted hydroxyapatite (CHA). Smaller and thicker actin rings on SiHA as compared to HA were probably the result of altered surface chemistry and solubility differences. The more stable sealing zones and increased lattice solubility likely contributed to increased individual pit volumes observed on Si0.5 HA. The delayed formation of OCs on Si0.5 HA (lower numbers at day 14) excludes earlier differentiation as a possible mechanism of increased individual OC pit volumes at later times (day 21). Materials characterization of Si containing biomaterials remains paramount as the Si type and amounts can subsequently impact downstream OC behaviour in a complex manner. PMID:25847383

  14. Preparation of nano-hydroxyapatite particles with different morphology and their response to highly malignant melanoma cells in vitro

    NASA Astrophysics Data System (ADS)

    Li, Bo; Guo, Bo; Fan, Hongsong; Zhang, Xingdong

    2008-11-01

    To investigate the effects of nano-hydroxyapatite (HA) particles with different morphology on highly malignant melanoma cells, three kinds of HA particles with different morphology were synthesized and co-cultured with highly malignant melanoma cells using phosphate-buffered saline (PBS) as control. A precipitation method with or without citric acid addition as surfactant was used to produce rod-like hydroxyapatite (HA) particles with nano- and micron size, respectively, and a novel oil-in-water emulsion method was employed to prepare ellipse-like nano-HA particles. Particle morphology and size distribution of the as prepared HA powders were characterized by transmission electron microscope (TEM) and dynamic light scattering technique. The nano- and micron HA particles with different morphology were co-cultured with highly malignant melanoma cells. Immunofluorescence analysis and MTT assay were employed to evaluate morphological change of nucleolus and proliferation of tumour cells, respectively. To compare the effects of HA particles on cell response, the PBS without HA particles was used as control. The experiment results indicated that particle nanoscale effect rather than particle morphology of HA was more effective for the inhibition on highly malignant melanoma cells proliferation.

  15. 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 stage of amelogenesis. PMID:25407797

  16. 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.

  17. The deposition of strontium-substituted hydroxyapatite coatings.

    PubMed

    Boyd, Adrian R; Rutledge, L; Randolph, L D; Mutreja, I; Meenan, B J

    2015-02-01

    Strontium substituted hydroxyapatite (SrHA) coatings have received a lot of interest recently as strontium (Sr) has been shown to have the dual benefit of promoting bone formation and reducing bone resorption, in vivo. In this work, SrHA coatings were deposited onto polycrystalline titanium surfaces using radio frequency (RF) magnetron co-sputtering and compared to those deposited from HA alone. In particular, the influence of different levels of Sr-substitution of the sputtering targets (5 and 13% Sr-substituted HA targets) on the properties of the deposited coatings produced at a low discharge power level (150 W) were investigated using FTIR, XPS, XRD, ToFSIMS and AFM techniques (both before and after annealing at 500 °C). The results show that Sr could be successfully incorporated into the HA lattice to form SrHA coatings and that they contained no other impurities. However, the coating produced from the 13% Sr-substituted target had a higher Ca+Sr/P ratio (1.95±0.14) and Sr content when compared to the coating produced from the 5% Sr-substituted target (1.58±0.20). The deposition rate also decreased with increasing Sr content of the sputtering targets. Furthermore, as the Sr content of the coatings increased, so did the preferred 002 orientation of the coating along with increased surface roughness and heterogeneity of the surface features. Therefore, this study has shown that RF magnetron sputtering offers a means to control attendant properties of Sr-substituted HA, such as the crystallinity, stoichiometry, phase purity and surface topography. PMID:25631262

  18. 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, Czes?awa; Czechowska, Joanna; ?lsarczyk, 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.

  19. MC3T3-E1 osteoblast attachment and proliferation on porous hydroxyapatite scaffolds fabricated with nanophase powder

    PubMed Central

    Smith, Ian O; McCabe, Laura R; Baumann, Melissa J

    2006-01-01

    Porous bone tissue engineering scaffolds were fabricated using both nano hydroxyapatite (nano HA) powder (20 nm average particle size) and micro HA powder (10 μm average particle size), resulting in sintered scaffolds of 59 vol% porosity and 8.6±1.9 μm average grain size and 72 vol% porosity and 588±55 nm average grain size, respectively. Scanning electron microscopy was used to measure both the grain size and pore size. MC3T3-E1 osteoblast (OB) attachment and proliferation on both nano HA and micro HA porous scaffolds were quantified. As expected, OB cell number was greater on nano HA scaffolds compared with similarly processed micro HA scaffolds 5 days after seeding, while OB attachment did not appear greater on the nano HA scaffolds (p<0.05). PMID:17722535

  20. Mechanical and biological properties of photocurable oligolactide-HA composites investigated under accelerated degradation.

    PubMed

    Channasanon, Somruethai; Kaewkong, Pakkanun; Uppanan, Paweena; Tanodekaew, Siriporn

    2016-05-01

    The major concern related to biodegradable bone substitute materials is the loss of mechanical strength which can be undesirable when occurring too quickly before new bone formation. In this study, the multifunctional lactide oligomers having 2, 3, and 4 arms end capped with methacrylate groups were synthesized with the aim of improving the degradation properties. Their composites with hydroxyapatite (HA) were photopolymerized and subjected to accelerated degradation at 60 °C. The results showed that increasing number of arms significantly improved thermal and mechanical properties as well as biocompatibility of the composites. All composites although varying in number of arms had similar levels of bone-specific gene expression and calcification indicating their equal bioactivity in supporting bone formation. The high HA content in the composites was proposed to be responsible for enhanced osteoblast response, and this tended to suppress the effects of polymeric structure. PMID:26838814

  1. No medium-term advantage of electrochemical deposition of hydroxyapatite in cementless femoral stems.

    PubMed

    Flatøy, Bernhard; Röhrl, Stephan M; Bøe, Berte; Nordsletten, Lars

    2016-02-01

    Background and purpose - Hydroxyapatite has been used for a long time as an adjunct to enhance cementless fixation. The benefit of this is still debated, but new methods of hydroxyapatite deposition have emerged, offering possible gains. In order to investigate this further, we compared the migration pattern and periprosthetic bone remodeling in a cementless femoral stem with either electrochemically deposited hydroxyapatite-called Bonemaster (BM)-or a conventional plasma-sprayed hydroxyapatite (HA) coating. Patients and methods - 55 hips were randomized to either BM or HA cementless femoral stems. Patients were followed with radiostereometry (RSA), dual-energy X-ray absorptiometry (DXA), radiographic measurements, and hip questionnaires for 5 years. Results - For both stems, migration occurred mainly as subsidence and retroversion during the first 3 months. The BM group had a higher retroversion rate of 0.17° per month during this period, as compared to 0.06° per month for the HA group (p = 0.006). Thereafter, there was almost no movement in any direction for both stem types. Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing. The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years. There was a slightly higher resorption rate in Gruen zone 7 from 2 to 5 years in the BM group (1.3% per year; p = 0.04), but in a magnitude that would scarcely affect stem stability or survival. Interpretation - There were no clinically relevant differences between the 2 stems regarding stability or periprosthetic bone loss at 5 years. Electrochemically deposited HA does not appear to affect fixation or bone remodeling when compared to conventional plasma spraying at 5 years. Thus, at this point, Bonemaster appears to be safe. PMID:26364953

  2. 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. PMID:26478383

  3. Fabrication of Ti/HA composite and functionally graded implant by three-dimensional printing.

    PubMed

    Qian, Chao; Zhang, Fuqiang; Sun, Jian

    2015-01-01

    The aim of this study is to evaluate the feasibility of fabricating titanium(Ti)/hydroxyapatite(HA) composite and functionally graded implant by three-dimensional printing (3DP) technology. Nano-scale Ti and HA powders were mixed at the ratio of 8:2 and prepared with water-soluble binder. The Ti/HA composite CAD model was designed to be in cylinder shape (25 mm in diameter, 20 mm in height) with the 100% bond area in each layer. The functionally graded implant was 25 mm in diameter and 10 mm in height with two segments. The upper segment was composed of 100% Ti in each layer, whereas the lower was composed of 80%Ti/20%HA. The composite and functionally graded implant were fabricated by 3DP and sintered at 1200°C under protective argon atmosphere. There occurred a chemical reaction between Ti and HA, in which new resultants of Ca3(PO4)2, CaTiO3, TiO2 and CaO were created. The sintered Ti/HA composite had the aperture size from 50 to 150 μm and the compressive strength of 184.3±27.1 MPa. The result of this study demonstrated that it was feasible to fabricate Ti/HA composite and functionally graded implant by 3DP technology. The microstructure and mechanical properties of Ti/HA composite and functionally graded implant were conductive to bone cell ingrowth, resulting in the wide application of this biocomposite. PMID:25813951

  4. 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.

  5. 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.

  6. 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 microspheres, composed of micron-sized, metallic rhenium particles dispersed within a magnesium alumino borate glass matrix were produced by sintering ReO2 powder and glass frit at 1050°C. A 50 mg injection of radioactive rhenium glass microspheres containing 3.7 GBq of 186Re and 8.5 GBq of 188Re could be used to deliver a 100 Gy dose to a cancerous tumor, while limiting the total body dose caused by rhenium dissolution to approximately 1 mGy.

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

    PubMed Central

    Kutikov, Artem B.; Song, Jie

    2013-01-01

    Electrospun polymer/hydroxyapatite (HA) composites combining biodegradability with osteoconductivity are attractive for skeletal tissue engineering applications. However, most biodegradable polymers such as 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 incorporated a hydrophilic polyethylene glycol (PEG) block to 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 25 wt% 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 osteogenesis 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. PMID:23791675

  8. Mitochondria and nuclei dual-targeted heterogeneous hydroxyapatite nanoparticles for enhancing therapeutic efficacy of doxorubicin.

    PubMed

    Xiong, Hui; Du, Shi; Ni, Jiang; Zhou, Jianping; Yao, Jing

    2016-07-01

    Dual-targeted nanoparticles have been increasingly used to realize greater anti-proliferation effect by attacking double key sites of tumor cells. In order to retain nuclei inhibition effect and enhance DOX-induced apoptosis by mitochondrial pathway simultaneously, hyaluronic acid (HA) modified hydroxyapatite (HAP) nanoparticles (HAP-HA), the functional calcium-based tumor targeting nanoparticles, have been developed. In this nanosystem, HA acts as an active tumor-targeting ligand to bind the CD44 receptors which are overexpressed on the surface of tumor cells while HAP can load and deliver DOX to both nuclei and mitochondria of tumor cells. In this study, DOX-loaded HAP-HA nanoparticles (DOX/HAP-HA) exhibited satisfactory drug loading efficiency which was up to 214.55 ± 51.05 μg mg(-1) and showed a uniform nano-scaled particle size. The mitochondrial and nuclei targetability of DOX/HAP-HA was confirmed by confocal laser scanning microscopy analyses. Besides, western blot assay demonstrated that DOX/HAP-HA could markedly enhance mitochondrial cytochrome C leakage and thereby activate apoptotic cascade associated with it. In addition, in vivo anti-tumor efficacy and toxicity evaluation of DOX/HAP-HA indicated that DOX/HAP-HA was more effective and less harmful compared to other groups. DOX/HAP-HA might be a new promising targeted delivery system for effective cancer therapy. PMID:27105438

  9. Laser surface modification of hydroxyapatite coated Ti alloy

    SciTech Connect

    Kim, Young Kon; Kim, Sukyoung; Lee, Jun Hee

    1996-12-31

    Plasma spray hydroxyapatite(HA) coated titanium alloy specimens were laser treated with a CW CO{sub 2} laser and a pulsatile Nd-Yag laser. Surface morphology was studied with scanning electron microscope (SEM) and optical microscope. The Ca/P ratio and distributions were semiquantitatively analyzed with x-ray energy dispersive microanalyzer (EDX). X-ray diffraction pattern of laser treated specimen was obtained using a x-ray diffractometer (XRD) with CuK{alpha} radiation. Cytotoxicity was examined in a CO{sub 2} incubator. The interfacial shear modulus and shear strength was measured with a mechanical tester. Laser treatment on the HA plasma spray coated titanium alloy could change surface structure into glassy melted pool, dendritic structure and flake like structure. The distribution of Ca and P in laser melted zone (LMZ) became uniform. The Ca/P ratio decreased from 1.67 to 1.4 for CO{sub 2} laser treatment and to 1.0 for Nd-Yag laser treatment. There was no cytotoxicological difference between laser treated specimen and plasma spray coated one. Laser treated specimen showed higher interfacial shear modulus compare to the HA coated specimen. These results show that the newly formed LMZ can improve interfacial bond strength between HA and matrix without cytotoxicological deficit.

  10. 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

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

    PubMed Central

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

    2014-01-01

    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. Ca2+ 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. PMID:25866411

  12. Coupling system to a microsphere cavity

    NASA Technical Reports Server (NTRS)

    Iltchenko, Vladimir (Inventor); Maleki, Lute (Inventor); Yao, Steve (Inventor); Wu, Chi (Inventor)

    2002-01-01

    A system of coupling optical energy in a waveguide mode, into a resonator that operates in a whispering gallery mode. A first part of the operation uses a fiber in its waveguide mode to couple information into a resonator e.g. a microsphere. The fiber is cleaved at an angle .PHI. which causes total internal reflection within the fiber. The energy in the fiber then forms an evanescent field and a microsphere is placed in the area of the evanescent field. If the microsphere resonance is resonant with energy in the fiber, then the information in the fiber is effectively transferred to the microsphere.

  13. 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. PMID:25638672

  14. 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. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 476-481, 2016. PMID:25891947

  15. Blood modeling using polystyrene microspheres.

    PubMed

    Fukada, E; Seaman, G V; Liepsch, D; Lee, M; Friis-Baastad, L

    1989-01-01

    The steady flow viscosity at shear rates 0 to 120 sec-1 and dynamic viscoelasticity at frequencies 0.02 to 0.8 Hz were determined for aqueous suspensions of uniform polystyrene microspheres of 1.0 micron diameter. Rheological properties of the microsphere suspensions were Newtonian for particle concentrations up to 32%. By introducing dextran and calcium chloride into the particle suspensions, non-Newtonian behavior was produced similar to that observed for human blood. The cooperative effects of dextran and calcium ions promoted aggregation of particles at a concentration as low as 12%. Thus, a suspension of uniform sized spherical polystyrene particles in aqueous solution of dextran may be made to mimic blood by controlling the surface charge on the polystyrene spheres using addition of calcium ions to the medium. PMID:2481519

  16. 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.

  17. 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.

  18. [Expression of AIV subtype H5HA, H7HA and H9HA hemagglutinin gene in Pichia pastoris].

    PubMed

    Xu, Yi-Ming; Jin, Ning-Yi; Xia, Zhi-Ping; Ma, Ming-Xiao; Lu, Hui-Jun; Han, Song; Jin, Kuo-Shi; Liang, Guo-Dong

    2006-03-01

    The expression of the hemagglutinins of Avian influenza virus H5 H7and H9 subtypes was studied in this article by Pichia pastoris, one of the eukaryotis expression systems. Three reconstructed expression plasmids and engineering strains, named pPIC9K-H5HA, pPIC9K-H7HA, pPIC9K-H9HA and GS115/pPIC9K-H5HA, GS115/pPIC9K-H7HA, GS115/pPIC9K-H9HA repectively, were obtained. The reconstructed yeast engineering strains were identified by MD and MM plate selecting and PCR. The induced interests proteins were examined by SDS-PAGE and Western-bloting,the results showed that the interest genes were expressed exactly. And this will be helpful in the future study of antigen detection and antibody detection kit, as well in the subunit vaccines developing. PMID:16607949

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Segmental stability in orthognathic surgery: hydroxyapatite/Poly-l-lactide osteoconductive composite versus titanium miniplate osteosyntheses.

    PubMed

    Landes, Constantin A; Ballon, Alexander; Tran, Andreas; Ghanaati, Shahram; Sader, Robert

    2014-09-01

    Hydroxyapatite was included into F-u-HA/PLLA (unsintered hydroxyapatite - Poly l-lactide) composite osteosynthesis material for its documented osteoconductive capacity. This study investigates segmental retention capacities and outcome stability using F-u-HA/PLLA composite osteosyntheses in orthognathic surgery. Of fifty patients in total, 25 patients were osteofixated with F-u-HA/PLLA osteoconductive bioabsorbable osteosyntheses and compared to a group of 25 patients treated with titanium miniplates. The F-u-HA/PLLA group included 14 maxillary advancements, 4 setbacks, 13 impactions, 5 elongations at A-point; the titanium group included 20 maxillary advancements, 2 setbacks, 11 impactions and 11 elongations. In the mandible the F-u-HA/PLLA group included 13 advancements at B-point, 11 setbacks, 16 clockwise rotations and 8 counterclockwise rotations at the Gonial angle (Ar-Go-Gn); the titanium group included 9 mandibular advancements, 5 setbacks, 8 clockwise rotations and 6 counterclockwise rotations at Ar-Go-Gn. Segmental stability and relapse were assessed comparing preoperative, postoperative and follow-up roentgen cephalometrics at 22 ± 11 months on average in F-u-HA/PLLA cases, 24 ± 22 months on average in the titanium group. All absolute operative movements were nonsignificant in the F-u-HA/PLLA cases compared to the titanium osteosynthesis cases. Relapses were nonsignificant but there was greater vertical relapse in maxillary impactions with titanium osteosyntheses. Throughout this study, F-u-HA/PLLA composite osteosyntheses appeared as stable as titanium miniplates. It can therefore be concluded, although from a limited number of patients, that the investigated osteoconductive osteosynthesis can be used in a similar way to titanium miniplates in orthognathic surgery. Compared to earlier studies using other bioabsorbable polymers in the literature, F-u-HA/PLLA proved to be more stable in segmental retention. PMID:24534684

  6. 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.

  7. Histomorphological researches on large porous hydroxyapatite cylinder tubes with polylactic acid surface coating in different nonskeletal sites in vivo.

    PubMed

    Zhang, Cong; Huang, Peng; Weng, Jie; Zhi, Wei; Hu, Yonghe; Feng, Huaizhi; Yao, Yimin; Li, Shuo; Xia, Tian

    2012-05-01

    Porous hydroxyapatite (HA) ceramic cylinder tubes coated with polylactic acid on the exposed surfaces were implanted in four nonskeletal sites (omentum, peritoneum, vastus lateralis, and side of femur). Six months postoperatively, proper amount of Chinese ink was injected to dye the implanting areas. Decalcified and nondecalcified sections were observed under inverted microscope. The results showed that the soft tissues around the HA cylinder tubes in peritoneum, vastus lateralis, and side of femur groups appeared visible black. Some small blacked vascular architectures were also discernible. However in omentum group, only small number of blacked vessels existed. Histological observations indicated that vascularization and ossification occurred in peritoneum, vastus lateralis, and side of femur groups. In omentum group, there was no any sign of vascularization and ossification. A conclusion could be made in this study that excepting bones and muscles, parietal peritoneum could serve as a potential spot for culturing histoengineering hydroxyapatite (HA)-polylactic acid (PLA) ceramic bone substitutes. PMID:22344718

  8. 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. PMID:20883835

  9. Nano-Particle Formation of Mn/HA on the Ti-35Ta-xNb Alloy by Electrochemical Methods.

    PubMed

    Jo, Chae-Ik; Choe, Han-Cheol

    2015-08-01

    In this study, nano-particle formation of Mn/HA on the Ti-35Ta-xNb alloy by electrochemical methods has researched using various experiments. These alloys were performed by arc-melting furnace and then heat treated for 1000 C at 12 h in Ar gas atmosphere and quenched at 0 C water. Hydroxyapatite precipitation has been synthesized from 5 mM Ca(NO3)2 4 H2O+3 mM NH4H2PO4 at 801 C. Manganese doped Hydroxyapatite precipitation has been synthesized from 4.95 mM Ca(NO3)2 4 H2O+3 mM NH4H2PO4+0.05 mM MnCl2 4 H2O at 801 C. Morphology and structure were examined by FE-SEM, EDS and XRD. The microstructure of Ti-35Ta-xNb alloys was transformed from a phase to ? phase as Nb content increased. The nano-scale HA shapes were plate-like precipitates and Mn doped HA shapes were net-like precipitates on Ti-35Ta-xNb alloys, and Ca, P and Mn peaks were detected on the Mn/HA deposited surface. PMID:26369210

  10. Improved biocompatibility of hydroxyapatite thin film prepared by aerosol deposition.

    PubMed

    Park, Dong-Soo; Kim, In-Sook; Kim, Hyeongil; Chou, Alex Hung Kuo; Hahn, Byung-Dong; Li, Long-Hao; Hwang, Soon-Jung

    2010-08-01

    Technical development for an efficient coating of bioactive materials improves the characteristics of a fully functional implant. The aim of this study was to investigate the osteoinductive effect of a newly developed hydroxyapatite (HA)-coating technique using aerosol deposition without post-heat treatment [room temperature (RT) group] on the titanium (Ti) dental implant in vitro and in vivo, compared with that of HA coating with post-heat treatment (HT-400 group) or machined surface (control group). Cell proliferation or attachment on the HA-coated Ti surface was assessed using tetrazolium salt, WST-8 or scanning electron microscopy (SEM). Human osteoblasts (HOB) on RT group were well attached and grew alike in the control or HT-400 group. The alkaline phosphatase activity of HOB cultured on RT and HT-400 group was significantly higher than the control group (p < 0.05). Evaluation by SEM, TEM, and XRD demonstrated that aerosol deposition facilitated HA particles to form a dense and uniform HA layer in the RT group despite no post-heating. In a rabbit tibia model (n = 3), the ratios of bone implant contact and bone area in the RT group (49.88%, 86.05%) were greater than in the HT-400 group (38.82%, 77.34%) or the control (28.31%, 73.86%). The finding of this study showed that the HA coating using aerosol deposition without post-heat treatment has a good biocompatibility, and provide a promoting strategy to enhance osseointegration in the application of the dental implant. PMID:20574972

  11. Bone tissue engineering with a collagen–hydroxyapatite scaffold and culture expanded bone marrow stromal cells

    PubMed Central

    Villa, Max M.; Wang, Liping; Huang, Jianping; Rowe, David W.; Wei, Mei

    2015-01-01

    Osteoprogenitor cells combined with supportive biomaterials represent a promising approach to advance the standard of care for bone grafting procedures. However, this approach faces challenges, including inconsistent bone formation, cell survival in the implant, and appropriate biomaterial degradation. We have developed a collagen–hydroxyapatite (HA) scaffold that supports consistent osteogenesis by donor derived osteoprogenitors, and is more easily degraded than a pure ceramic scaffold. Herein, the material properties are characterized as well as cell attachment, viability, and progenitor distribution in vitro. Furthermore, we examined the biological performance in vivo in a critical-size mouse calvarial defect. To aid in the evaluation of the in-house collagen–HA scaffold, the in vivo performance was compared with a commercial collagen–HA scaffold (Healos®, Depuy). The in-house collagen–HA scaffold supported consistent bone formation by predominantly donor-derived osteoblasts, nearly completely filling a 3.5 mm calvarial defect with bone in all samples (n=5) after 3 weeks of implantation. In terms of bone formation and donor cell retention at 3 weeks postimplantation, no statistical difference was found between the in-house and commercial scaffold following quantitative histomorphometry. The collagen–HA scaffold presented here is an open and well-defined platform that supports robust bone formation and should facilitate the further development of collagen–hydroxyapatite biomaterials for bone tissue engineering. PMID:24909953

  12. The effects of ageing time on the microstructure and properties of mesoporous silica-hydroxyapatite nanocomposite

    NASA Astrophysics Data System (ADS)

    Yousefpour, Mardali; Taherian, Zahra

    2013-02-01

    In this study, a mesoporous silica-hydroxyapatite nanocomposite (MCM-41/HA) was synthesized via sol-gel technique as a drug delivery system. The synthesis of MCM-41/hydroxyapatite nanocomposite was carried out at room temperature. The effect of various ageing time on the nanocomposite properties was studied during synthesis process. 0, 24, 36, and 48 h aging times were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Electron Diffraction pattern (ED), and N2 adsorption-desorption. Results showed that ageing process led to HA crystals nucleation and growth on the surface of mesoporous silica. At 48 h of aging time, the surface area and total pore volume increased from 36.2 to 334 m2/g and 0.14-0.7 cm3/g, respectively. In contrast, the average pore diameter considerably decreased from 20.1 nm for (MCM-41/HA)24 to 8.39 nm for (MCM-41/HA)48. Furthermore, it was observed more homogeneous pore distribution with increasing the ageing time. In conclusion, the ageing time play an important role on textural properties of MCM-41/HA nanocomposite which could have a major effect on drug delivery properties such as molecular loading and release kinetics.

  13. The drainage of the Lake Ha!Ha! reservoir and downstream geomorphic impacts along Ha!Ha! River, Saguenay area, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Brooks, G. R.; Lawrence, D. E.

    1999-05-01

    On July 18-21, 1996, a severe rainstorm caused widespread flooding along the north shore of the St. Lawrence River, southern Quebec, Canada, particularly along rivers that drain the area just south of the Saguenay-Lake St. Jean region. At the Lake Ha!Ha! reservoir, inadequate available capacity to spill during the storm at the outlet dam resulted in the overtopping and erosion of a nearby earthfill saddle dyke. A new outlet formed at the site of the dyke and drained the reservoir over a period of many hours decreasing its area from 8.1 to 4.7 km 2. Estimates of discharge range from 910 to 1380 m 3 s -1 at the site of the eroded dyke to 1080 to 1260 m 3 s -1 at a location 27 km downstream (about 8 km above the mouth of the river). The uncontrolled drainage of the Lake Ha!Ha! reservoir increased flooding along the lower 35 km of Ha!Ha! River where flooding was already in progress because of the rainstorm runoff. The flooding caused extensive geomorphic impacts along the river. Long sections of the river (totalling 25 km) experienced significant widening (locally up to 280 m) and channel incision (locally up to 20 m) while two reaches (6 and 4.5 km long) experienced up to several metres of aggradation. In general, the slope of the valley was the most important variable affecting whether or not the energy of the flow was above or below the erosive threshold of the valley bottom. Locally, a permanent channel diversion now exists where the drainage divide between the main river course and a small ravine was overtopped and extensively eroded. Communities, infrastructure, and industry located along the river were extensively damaged by the flood waters. The effects of flooding along Ha!Ha! River demonstrate that rivers on the Canadian Shield can undergo severe geomorphic changes caused by very high-magnitude flooding.

  14. 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. PMID:21676601

  15. Cellular proliferation, cellular viability, and biocompatibility of HA-ZnO composites.

    PubMed

    Saha, Naresh; Dubey, Ashutosh K; Basu, Bikramjit

    2012-01-01

    One of the important issues in the development of hydroxyapatite (HA)-based biomaterials is the prosthetic infection, which limits wider use of monolithic HA despite superior cellular response. Recently, we reported that ZnO addition to HA can induce bactericidal property. It is therefore important to assess how ZnO addition influences the cytotoxicity property and cell adhesion/proliferation on HA-ZnO composite surfaces in vitro. In the above perspective, the objective of this study is to investigate the cell type and material composition dependent cellular proliferation and viability of pressureless sintered HA-ZnO composites. The combination of cell viability data as well as morphological observations of cultured human osteoblast-like SaOS2 cells and mouse fibroblast L929 cells suggests that HA-ZnO composites containing 10 Wt % or lower ZnO exhibit the ability to support cell adhesion and proliferation. Both SaOS2 and L929 cells exhibit extensive multidirectional network of actin cytoskeleton and cell flattening on the lower ZnO containing (≤10 Wt %) HA-ZnO composites. The in vitro results illustrate how variation in ZnO content can influence significantly the cell vitality, as evaluated using MTT biochemical assay. Also, the critical statistical analysis reveals that ZnO addition needs to be carefully tailored to ensure good in vitro cytocompatibility. The underlying reasons for difference in biological properties are analyzed. It is suggested that surface wettability as well as dissolution of ZnO, both contribute to the observed differences in cellular viability and proliferation. PMID:22102555

  16. 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.

  17. Preparation and characterization of NiW-nHA composite catalyst for hydrocracking.

    PubMed

    Zhou, Gang; Hou, Yongzhao; Liu, Lei; Liu, Hongru; Liu, Can; Liu, Jing; Qiao, Huiting; Liu, Wenyong; Fan, Yubo; Shen, Shituan; Rong, Long

    2012-12-21

    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 CaWO(4) 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 C(15) to C(18) were the main components in the production. The yield of C(15)-C(18) alkanes was up to 83.56 wt%. The reaction pathway involved hydrocracking of the C═C bonds of these triglycerides from Jatropha oil. This paper developed a novel non-sulfided catalyst to obtain a "green biofuel" from vegetable oil. PMID:23128670

  18. Silver oxide-containing hydroxyapatite coating supports osteoblast function and enhances implant anchorage strength in rat femur.

    PubMed

    Eto, Shuichi; Miyamoto, Hiroshi; Shobuike, Takeo; Noda, Iwao; Akiyama, Takayuki; Tsukamoto, Masatsugu; Ueno, Masaya; Someya, Shinsuke; Kawano, Shunsuke; Sonohata, Motoki; Mawatari, Masaaki

    2015-09-01

    Antibacterial silver with hydroxyapatite (Ag-HA) is a promising coating material for imparting antibacterial properties to implants. We previously reported that 3% (w/w) silver with HA (3% Ag-HA) has both antibacterial activity and osteoconductivity. In this study, we investigated the effects of Ag-HA on the in vitro osteoblast function and the in vivo anchorage strength and osteoconductivity of implants. Production of the osteoblast marker alkaline phosphatase, but not cytotoxicity, was observed in cells of the osteoblast cell line MC3T3-E1 cultured on the 3% Ag-HA-coated surface. These results were similar to those observed with silver-free HA coating. In contrast, a significant high level of cytotoxicity was observed when the cells were cultured on a 50% Ag-HA-coated surface. The anchorage strength of implants inserted into the femur of Sprague-Dawley (SD) rats was enhanced by coating the implants with 3% Ag-HA. On the 3% Ag-HA-coated surface, both metaphyseal and diaphyseal areas were largely covered with new bone and had adequate osteoconductivity. These results suggest that 3% Ag-HA, like conventional HA, promotes osteogenesis by supporting osteoblast viability and function and thereby contributes to sufficient anchorage strength of implants. Application of 3% Ag-HA, which combines the osteoconductivity of HA and the antibacterial activity of silver, to prosthetic joints will help prevent postoperative infections. PMID:25808232

  19. 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 hierarchically nanosized HA with flower-like structure assembled from nanosheets consisting of nanorod building blocks. The HA with the hierarchical nanostructure was formed via a soft-template assisted self-assembly mechanism. The hierarchically nanostructured HA has a good biocompatibility and essentially no in-vitro cytotoxicity. PMID:22619527

  20. 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 magnitude, which can result in unique properties in areas such as hydrogen storage, gas transport, gas separations and purifications, sensors, global warming applications, new drug delivery systems and so on. One of the most interesting porous glass products that SRNL has developed and patented is Porous Wall, Hollow Glass Microspheres (PW-HGMs) that are being studied for many different applications. The European Patent Office (EPO) just recently notified SRS that the continuation-in-part patent application for the PW-HGMs has been accepted. The original patent, which was granted by the EPO on June 2, 2010, was validated in France, Germany and the United Kingdom. The microspheres produced are generally in the range of 2 to 100 microns, with a 1 to 2 micron wall. What makes the SRNL microspheres unique from all others is that the team in Figure 1 has found a way to induce and control porosity through the thin walls on a scale of 100 to 3000 {angstrom}. This is what makes the SRNL HW-HGMs one-of-a-kind, and is responsible for many of their unique properties and potential for various applications, including those in tritium storage, gas separations, H-storage for vehicles, and even a variety of new medical applications in the areas of drug delivery and MRI contrast agents. SRNL Hollow Glass Microspheres, and subsequent, Porous Wall, Hollow Glass Microspheres are fabricated using a flame former apparatus. Figure 2 is a schematic of the apparatus.

  1. 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. PMID:26652452

  2. 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.

  3. Influence of Magnesium Ion Substitution on Structural and Thermal Behavior of Nanodimensional Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Batra, Uma; Kapoor, Seema; Sharma, Sonia

    2013-06-01

    Hydroxyapatite (HA), incorporating small amount of magnesium, shows attractive biological performance in terms of improved bone metabolism, osteoblast and osteoclast activity, and bone in-growth. This article reports a systematic investigation on the influence of magnesium (Mg) substitution on structural and thermal behavior of nanodimensional HA. HA and Mg-substituted HA nanopowders were synthesized through sol-gel route. The morphology and size of nanopowders were characterized by transmission electron microscopy. The BET surface area was evaluated from N2 adsorption isotherms. Structural analysis and thermal behavior were investigated by means of Fourier transform infrared spectroscopy, x-ray diffraction, thermogravimetry, and differential thermal analysis. As-synthesized powders consisted of flake-like agglomerates of HA and calcium-deficient HA. The incorporation of magnesium in HA resulted in decrease of crystallite size, crystallinity, and lattice parameters a and c and increase in BET surface area. β-tricalcium phosphate formation occured at lower calcination temperature in Mg-substituted HA than HA.

  4. Densification Process of OH Controlled Hydroxyapatite Ceramics by Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Kawagoe, D.; Koga, Y.; Ishida, E. H.; Ioku, K.

    2006-05-01

    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 °C, 900 °C and 1000 °C for 10 min with the heating rate of 25 °Cṡmin-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 °C and 1000 °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.

  5. 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. PMID:22606041

  6. 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

  7. 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. PMID:26369028

  8. 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. PMID:23348918

  9. Chondroitin sulfate template-mediated biomimetic synthesis of nano-flake hydroxyapatite

    NASA Astrophysics Data System (ADS)

    He, Dan; Xiao, Xiufeng; Liu, Fang; Liu, Rongfang

    2008-11-01

    By Ca(NO 3) 2·4H 2O and (NH 4) 3PO 4·3H 2O as reagents and chondroitin sulfate (ChS) as a template, nano-flake hydroxyapatite (HA) is synthesized using a biomimetic method according to the biomineralization theory. HA crystals obtained are characterized in crystalline phase, microstructure, chemical composition and morphology by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), transmission electron microscopy (TEM) and elemental analysis respectively. UV-vis spectrum is adopted to investigate interactions between functional groups ChS and HA. The results show that HA crystal nucleation and growth take place in chemical interactions between HA crystals and ChS as a template. And elemental analysis indicates that obtained HA contains a small amount of ChS. Furthermore, ChS concentration significantly affects the morphology of HA crystals. Staple-fiber-like HA crystals can be obtained at a low concentration in ChS, and flake-like HA crystals synthesized at a high concentration (≥0.5 wt.%) of ChS as a template.

  10. 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

  11. Microsphere fluoroimmunoassay for microorganisms: An update

    SciTech Connect

    Whitten, W.B.; Ramsey, J.M.; Bronk, B.V.

    1994-12-31

    Microspheres are used as labels in a fluorescence immunoassay for individual microorganisms. The diameter of a sphere that has reacted with microorganisms is determined from measurements of the optical resonance frequencies. The spheres have been coated with antibodies so that each microsphere diameter corresponds to a different species of microorganism. Further experiments on specificity and on optical resonance measurements are presented.

  12. 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 DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1360 Trace microsphere....

  13. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Trace microsphere. 870.1360 Section 870.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1360 Trace microsphere....

  14. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Trace microsphere. 870.1360 Section 870.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1360 Trace microsphere....

  15. Microsphere estimates of blood flow: Methodological considerations

    SciTech Connect

    von Ritter, C.; Hinder, R.A.; Womack, W.; Bauerfeind, P.; Fimmel, C.J.; Kvietys, P.R.; Granger, D.N.; Blum, A.L. Louisianna State Univ. Medical Center, Shreveport Universitaire Vaudois )

    1988-02-01

    The microsphere technique is a standard method for measuring blood flow in experimental animals. Sporadic reports have appeared outlining the limitations of this method. In this study the authors have systematically assessed the effect of blood withdrawals for reference sampling, microsphere numbers, and anesthesia on blood flow estimates using radioactive microspheres in dogs. Experiments were performed on 18 conscious and 12 anesthetized dogs. Four blood flow estimates were performed over 120 min using 1 {times} 10{sup 6} microspheres each time. The effects of excessive numbers of microspheres pentobarbital sodium anesthesia, and replacement of volume loss for reference samples with dextran 70 were assessed. In both conscious and anesthetized dogs a progressive decrease in gastric mucosal blood flow and cardiac output was observed over 120 min. This was also observed in the pancreas in conscious dogs. The major factor responsible for these changes was the volume loss due to the reference sample withdrawals. Replacement of the withdrawn blood with dextran 70 led to stable blood flows to all organs. The injection of excessive numbers of microspheres did not modify hemodynamics to a greater extent than did the injection of 4 million microspheres. Anesthesia exerted no influence on blood flow other than raising coronary flow. The authors conclude that although blood flow to the gastric mucosa and the pancreas is sensitive to the minor hemodynamic changes associated with the microsphere technique, replacement of volume loss for reference samples ensures stable blood flow to all organs over a 120-min period.

  16. Effect of silver additive on physicochemical properties of hydroxyapatite applied to reconstructive surgery

    NASA Astrophysics Data System (ADS)

    Zhuk, I. V.; Rasskazova, L. A.; Korotchenko, N. M.

    2015-11-01

    The effect of silver adding to hydroxyapatite (HA) in its solubility in physiological solution and biological activity was investigated. Samples of HA containing silver (AgHA) obtained by liquid-phase method in the conditions of microwave exposure. Solubility (CCa2+.103, mol/l) of the powders AgHA was determined by chemical methods according trilonometric titration of the calcium ions in physiological solution at 25 and 37 °C. To investigate the biological activity of the samples, a series of experiments on the formation of the calcium-phosphate layer on the surface of the SBF-solution at 37 °C for 28 days. Electronic micrographs of samples taken at the end of each 7 days of the experiment, indicate the formation of calcium-phosphate layer (CPL) in the samples, the kinetics of which is shown as a function of cumulative concentrations of calcium and magnesium ions from time.

  17. 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. PMID:25706198

  18. Preparation and characterization of porous PDLLA/HA composite foams by supercritical carbon dioxide technology.

    PubMed

    Teng, Xinrong; Ren, Jie; Gu, Shuying

    2007-04-01

    A composite poly(D,L)lactic acid (PDLLA)/hydroxyapatite (HA) biomaterial was prepared by in situ polymerization of D,L-lactide monomer and HA. Supercritical CO2 (SC CO2) technology was developed to prepare the biodegradable composite foams for use in tissue regeneration. In this technology, NaCl particles were used as porogen to produce an open-pore structure. Organic solvents were not used and high temperature was not necessary. The problem with pore interconnectivity was resolved. High-porosity composite foams (up to 90% +/- 2% porosity) were obtained with pore sizes ranging from 100 to 300 microm suitable for cell seeding. The microstructure and morphology of the composite foams could be controlled by saturation pressure, saturation time, and temperature as well as amount of NaCl particles. The compressive strength and water absorbability of the composite foams were also determined. With an increase in HA amount, the molecular weight of PDLLA/HA composite foams decreased, but the mechanical strength and hydrophilicity increased slightly. PMID:16924605

  19. 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. PMID:10880116

  20. 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

  1. Hydrothermal synthesis of CdSe microspheres

    NASA Astrophysics Data System (ADS)

    Pawar, Sachin A.; Patil, D. S.; Pawar, S. B.; Bhat, T. S.; Waifalkar, P. P.; Pisal, S. H.; Bhosale, P. N.; Patil, P. S.

    2013-06-01

    Cadmium selenide (CdSe) microspheres have been synthesized by a cost-effective, simple and versatile hydrothermal deposition method onto soda-lime glass substrates. The thin films of CdSe microspheres were characterized for their optical absorbance/transmittance, optical band gap, photoluminescence and surface morphological study. CdSe microspheres show visible light absorbance of solar spectrum while is suffering from low optical transmittance. The optical band gap energy of CdSe microspheres was found to be 1.89 eV. Photoluminescence study involves one measure peak at 615 nm accompanying two more small peaks. The surface morphological study of CdSe thin film resembles a formation of microspheres which are interpenetrating with each other is seen at higher magnifications.

  2. Integrated Cryogenic Experiment (ICE) microsphere investigation

    NASA Technical Reports Server (NTRS)

    Spradley, I.; Read, D.

    1989-01-01

    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.

  3. Multiplexed Microsphere Suspension Array-Based Immunoassays.

    PubMed

    Lin, Andrew; Salvador, Alexandra; Carter, J Mark

    2015-01-01

    ELISA is an extremely powerful tool to detect analytes because of its sensitivity, selectivity, reproducibility and ease of use. Here we describe sandwich immunoassays performed in suspension on spectrally unique microspheres developed by Luminex. Luminex assays offer the benefit of multiplex analysis of large numbers of analytes in a single reaction. Because the microspheres are spectrally unique, many microspheres, each attached to various antibodies, can be added to a single sample. Luminex instruments can distinguish each microsphere and detect the intensity of a reporter signal for each microsphere. Results are reported in Median Fluorescent Intensities for each analyte. Luminex assays can be used to detect up to 500 analytes in a high-throughput format. Luminex refers to this technology as xMAP(®). Here we describe a routine protocol for a Luminex immunoassay. Other Luminex assays would have to be optimized for specific conditions according to their use. PMID:26160569

  4. From Zn microspheres to hollow ZnO microspheres: A simple route to the growth of large scale metallic Zn microspheres and hollow ZnO microspheres

    NASA Astrophysics Data System (ADS)

    Khan, Aurangzeb; Jadwisienczak, Wojciech M.; Kordesch, Martin E.

    2006-07-01

    Large scale metallic Zn microspheres and hollow ZnO microspheres are synthesized by thermal evaporation and vapor transport by heating a ZnO/graphite mixture at 1000 °C. Firstly, metallic Zn microspheres are fabricated with diameters in the range of 1-10 μm. The Zn microspheres are then annealed at 600 °C in air, which form hollow semiconducting ZnO microspheres. EDX and XRD spectra reveal that the oxidized material is indeed ZnO. Room temperature photoluminescence spectra of the oxidized material show a sharp peak at ∼380 nm and a wider broad peak centered at ∼490 nm. This growth mechanism is discussed and further investigated for other metallic and metal oxide microstructures.

  5. 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.

  6. 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. PMID:26897095

  7. 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.

  8. Bone integration capability of nanopolymorphic crystalline hydroxyapatite coated on titanium implants

    PubMed Central

    Yamada, Masahiro; Ueno, Takeshi; Tsukimura, Naoki; Ikeda, Takayuki; Nakagawa, Kaori; Hori, Norio; Suzuki, Takeo; Ogawa, Takahiro

    2012-01-01

    The mechanism by which hydroxyapatite (HA)-coated titanium promotes bone–implant integration is largely unknown. Furthermore, refining the fabrication of nano-structured HA to the level applicable to the mass production process for titanium implants is challenging. This study reports successful creation of nanopolymorphic crystalline HA on microroughened titanium surfaces using a combination of flame spray and low-temperature calcination and tests its biological capability to enhance bone–implant integration. Sandblasted microroughened titanium implants and sandblasted + HA-coated titanium implants were subjected to biomechanical and histomorphometric analyses in a rat model. The HA was 55% crystallized and consisted of nanoscale needle-like architectures developed in various diameters, lengths, and orientations, which resulted in a 70% increase in surface area compared to noncoated microroughened surfaces. The HA was free from impurity contaminants, with a calcium/phosphorus ratio of 1.66 being equivalent to that of stoichiometric HA. As compared to microroughened implants, HA-coated implants increased the strength of bone–implant integration consistently at both early and late stages of healing. HA-coated implants showed an increased percentage of bone–implant contact and bone volume within 50 μm proximity of the implant surface, as well as a remarkably reduced percentage of soft tissue intervention between bone and the implant surface. In contrast, bone volume outside the 50 μm border was lower around HA-coated implants. Thus, this study demonstrated that the addition of pure nanopolymorphic crystalline HA to microroughened titanium not only accelerates but also enhances the level of bone–implant integration and identified the specific tissue morphogenesis parameters modulated by HA coating. In particular, the nanocrystalline HA was proven to be drastic in increasing osteoconductivity and inhibiting soft tissue infiltration, but the effect was limited to the immediate microenvironment surrounding the implant. PMID:22359461

  9. Characteristic of microarc oxidized coatings on titanium alloy formed in electrolytes containing chelate complex and nano-HA

    NASA Astrophysics Data System (ADS)

    Wei, Daqing; Zhou, Yu; Wang, Yaming; Jia, Dechang

    2007-03-01

    Microarc oxidized (MAO) TiO 2-based coatings containing Ca and P on titanium alloy were formed in electrolytes containing nano-hydroxyapatite (nano-HA), calcium and phosphate salts. The effects of HA concentration on the thickness, micropore size and number of the MAO coatings were not pronounced. However, the surfaces of the MAO coatings become rough and the crystallinity of anatase increases with increasing HA concentration. In addition, the Ca and P concentrations on the surfaces of the MAO coatings decrease, since the chelate complex of CaY 2- (Y = [ 2(OOC)NCH 2CH 2N(COO) 2] 4-) and phosphate ions are hindered to be incorporated into the MAO coatings by HA. In vitro experiments indicate that the apatite-forming abilities of the MAO coatings decrease with increasing HA concentration. Furthermore, with increasing HA concentration, the solubility of Ca and P of the MAO coatings decreases, which could lower the supersaturation of the SBF with respect to apatite near the surfaces of the MAO coatings, further leading to the decreased apatite-forming ability. The results indicate that the HA addition in the electrolytes has an important effect on the structure and in vitro bioactivity of the MAO coatings.

  10. Morphological Effects of HA on the Cell Compatibility of Electrospun HA/PLGA Composite Nanofiber Scaffolds

    PubMed Central

    Haider, Adnan; Gupta, Kailash Chandra; Kang, Inn-Kyu

    2014-01-01

    Tissue engineering is faced with an uphill challenge to design a platform with appropriate topography and suitable surface chemistry, which could encourage desired cellular activities and guide bone tissue regeneration. To develop such scaffolds, composite nanofiber scaffolds of nHA and sHA with PLGA were fabricated using electrospinning technique. nHA was synthesized using precipitation method, whereas sHA was purchased. The nHA and sHA were suspended in PLGA solution separately and electrospun at optimized electrospinning parameters. The composite nanofiber scaffolds were characterized by FE-SEM, EDX analysis, TEM, XRD analysis, FTIR, and X-ray photoelectron. The potential of the HA/PLGA composite nanofiber as bone scaffolds in terms of their bioactivity and biocompatibility was assessed by culturing the osteoblastic cells onto the composite nanofiber scaffolds. The results from in vitro studies revealed that the nHA/PLGA composite nanofiber scaffolds showed higher cellular adhesion, proliferation, and enhanced osteogenesis performance, along with increased Ca+2 ions release compared to the sHA/PLGA composite nanofiber scaffolds and pristine PLGA nanofiber scaffold. The results show that the structural dependent property of HA might affect its potential as bone scaffold and implantable materials in regenerative medicine and clinical tissue engineering. PMID:24719853

  11. 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

  12. 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. PMID:26050880

  13. 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 bone scaffolds and understanding the interaction mechanism between binder and HA bioceramics power. PMID:26724560

  14. Interconnected porous hydroxyapatite ceramics for bone tissue engineering

    PubMed Central

    Yoshikawa, Hideki; Tamai, Noriyuki; Murase, Tsuyoshi; Myoui, Akira

    2008-01-01

    Several porous calcium hydroxyapatite (HA) ceramics have been used clinically as bone substitutes, but most of them possessed few interpore connections, resulting in pathological fracture probably due to poor bone formation within the substitute. We recently developed a fully interconnected porous HA ceramic (IP-CHA) by adopting the ‘foam-gel’ technique. The IP-CHA had a three-dimensional structure with spherical pores of uniform size (average 150 μm, porosity 75%), which were interconnected by window-like holes (average diameter 40 μm), and also demonstrated adequate compression strength (10–12 MPa). In animal experiments, the IP-CHA showed superior osteoconduction, with the majority of pores filled with newly formed bone. The interconnected porous structure facilitates bone tissue engineering by allowing the introduction of mesenchymal cells, osteotropic agents such as bone morphogenetic protein or vasculature into the pores. Clinically, we have applied the IP-CHA to treat various bony defects in orthopaedic surgery, and radiographic examinations demonstrated that grafted IP-CHA gained radiopacity more quickly than the synthetic HA in clinical use previously. We review the accumulated data on bone tissue engineering using the novel scaffold and on clinical application in the orthopaedic field. PMID:19106069

  15. Interfacial stress transfer in a graphene nanosheet toughened hydroxyapatite composite

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Zhang, X. G.; Chen, Y.; Su, J. N.; Liu, W. W.; Zhang, T. H.; Qi, F.; Wang, Y. G.

    2014-10-01

    In recent years, graphene has emerged as potential reinforcing nanofiller in the composites for structural engineering due to its extraordinary high elastic modulus and mechanical strength. As recognized, the transfer of stress from a low modulus matrix to a high-modulus reinforcing graphene and the interfacial behavior at a graphene-matrix interface is the fundamental issue in these composites. In the case of graphene nanosheet (GNS) reinforced hydroxyapatite (HA) composite, this research presented analytical models and simulated that the number of graphene layers of GNSs has little effect on the maximum axial stress (˜0.35 GPa) and the maximum shear stress (˜0.14 GPa) at a GNS-HA interface, and the energy dissipation by GNS pull-out decreases with increasing the number of graphene layers due to weak bonding between them. Also, GNS-HA interfacial delamination and/or GNS rupture were also indentified to be the two key failure mechanisms. The computed results are expected to facilitate a better understanding of the interfacial behavior at a GNS-ceramic interface and to achieve tough ceramics reinforced with GNSs.

  16. Adverse Biophysical Effects of Hydroxyapatite Nanoparticles on Natural Pulmonary Surfactant

    PubMed Central

    Fan, Qihui; Wang, Yi E.; Zhao, Xinxin; Loo, Joachim S. C.; Zuo, Yi Y.

    2016-01-01

    Inhaled nanoparticles (NPs) must first interact with the pulmonary surfactant (PS) lining layer that covers the entire internal surface of the respiratory tract and plays an important role in surface tension reduction and host defense. Interactions with the PS film determine the subsequent clearance, retention, and translocation of the inhaled NPs and hence their potential toxicity. To date, little is known how NPs interact with PS, and whether or not NPs have adverse effects on the biophysical function of PS. We found a time-dependent toxicological effect of hydroxyapatite NPs (HA-NPs) on a natural PS, Infasurf, and the time scale of surfactant inhibition after particle exposure was comparable to the turnover period of surfactant metabolism. Using a variety of in vitro biophysicochemical characterization techniques, we have determined the inhibition mechanism to be due to protein adsorption onto the HA-NPs. Consequently, depletion of surfactant proteins from phospholipid vesicles caused conversion of original large vesicles into much smaller vesicles with poor surface activity. These small vesicles, in turn, inhibited biophysical function of surfactant films after adsorption at the air–water interface. Cytotoxicity study found that the HA-NPs at the studied concentration were benign to human bronchial epithelial cells, thereby highlighting the importance of evaluating biophysical effect of NPs on PS. The NP–PS interaction mechanism revealed by this study may not only provide new insight into the toxicological study of nanoparticles but also shed light on the feasibility of NP-based pulmonary drug delivery. PMID:21761867

  17. Magnetic responsive hydroxyapatite composite scaffolds construction for bone defect reparation

    PubMed Central

    Zeng, Xiao Bo; Hu, Hao; Xie, Li Qin; Lan, Fang; Jiang, Wen; Wu, Yao; Gu, Zhong Wei

    2012-01-01

    Introduction In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. A type of magnetic scaffold composed of magnetic nanoparticles (MNPs) and hydroxyapatite (HA) for bone repair has been developed by our research group. Aim and methods In this study, to investigate the influence of the MNP content (in the scaffolds) on the cell behaviors and the interactions between the magnetic scaffold and the exterior magnetic field, a series of MNP-HA magnetic scaffolds with different MNP contents (from 0.2% to 2%) were fabricated by immersing HA scaffold into MNP colloid. ROS 17/2.8 and MC3T3-E1 cells were cultured on the scaffolds in vitro, with and without an exterior magnetic field, respectively. The cell adhesion, proliferation and differentiation were evaluated via scanning electron microscopy; confocal laser scanning microscopy; and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline phosphatase, and bone gla protein activity tests. Results The results demonstrated the positive influence of the magnetic scaffolds on cell adhesion, proliferation, and differentiation. Further, a higher amount of MNPs on the magnetic scaffolds led to more significant stimulation. Conclusion The magnetic scaffold can respond to the exterior magnetic field and engender some synergistic effect to intensify the stimulating effect of a magnetic field to the proliferation and differentiation of cells. PMID:22848165

  18. Stability of hydroxyapatite while processing short-fibre reinforced hydroxyapatite ceramics.

    PubMed

    Knepper, M; Moricca, S; Milthorpe, B K

    1997-12-01

    Reinforcement by short fibres has been adapted from modern ceramic processing technologies to achieve an improvement of structural properties of hydroxyapatite. However, the influence of the reinforcement fibres on the thermochemical behaviour of the hydroxyapatite has yet to be clarified comprehensively. Titanium, alumina and 316L-stainless steel, all materials with a proven record as implant materials, were chosen as reinforcement materials. Short fibres of these materials were incorporated in a matrix of hydroxyapatite to toughen the hydroxyapatite. Composites were processed by sintering in air, hot isostatic pressing and a method combining sintering in inert gas atmosphere and hot isostatic pressing. PMID:9430334

  19. Nanostructured Si, Mg, CO3 2- Substituted Hydroxyapatite Coatings Deposited by Liquid Precursor Plasma Spraying: Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Xiao, Yanfeng; Wang, Shanling; Huang, Yi; Liu, Xiaoguang; Wu, Fang; Gu, Zhongwei

    2011-06-01

    In this study, a novel liquid precursor plasma spraying (LPPS) process was used to deposit Si, Mg, CO3 2- substituted hydroxyapatite (HA) coatings (alone and cosubstituted) onto Ti-6Al-4V substrates. Salts of silicon, magnesium, and carbonate elements were directly added into the HA liquid precursor for subsequent plasma spraying. The phase composition, structure, and morphology of all HA coatings were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the trace elements were successfully incorporated into the HA structure and nanostructured coatings were obtained for all doped HA formulations. The incorporation of trace elements into the HA structure reduced its crystallinity, especially when silicon, magnesium and carbonate ions entered simultaneously into the HA structure. FTIR spectra showed that the Si-HA and Mg-HA coatings had decreased intensities in both the O-H and P-O bands and that the CO3 2--HA coating was mainly a B-type carbonate-substituted HA. The results showed that the LPPS process is an effective and simple method to synthesize trace element substituted biomimetic HA coatings with nanostructure.

  20. Evaluation of Bone Healing on Sandblasted and Acid Etched Implants Coated with Nanocrystalline Hydroxyapatite: An In Vivo Study in Rabbit Femur

    PubMed Central

    Melin Svanborg, Lory; Meirelles, Luiz; Franke Stenport, Victoria; Currie, Fredrik; Andersson, Martin

    2014-01-01

    This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA) were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone. PMID:24723952

  1. Characterization of high velocity oxy-fuel combustion sprayed hydroxyapatite.

    PubMed

    Haman, J D; Lucas, L C; Crawmer, D

    1995-02-01

    Bioceramic coatings, created by the high velocity oxy-fuel combustion spraying of hydroxyapatite (HA) powders onto commercially pure titanium, were characterized in order to determine whether this relatively new coating process can be successfully applied to bioceramic coatings of orthopaedic and dental implants. Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were used to characterize both the HA starting powders and coatings. A 12 wk immersion test was conducted and the resulting changes in the coatings were also characterized. Calcium ion release during dissolution was measured with flame atomic absorption during the first 6 weeks of the immersion study. A comparison of powder and coating X-ray diffraction patterns and lattice parameters revealed an HA-type coating with some loss in crystallinity. Fourier transform infrared results showed a partial loss of the OH- group during spraying, however the phosphate groups were still present. Scanning electron microscopy analysis showed a lamellar structure with very close coating-to-substrate apposition. The coatings experienced a loss of calcium during the immersion study, with the greatest release in calcium occurring during the first 6 days of the study. No significant structural or chemical changes were observed during the 12 wk immersion study. These results indicate that the high velocity oxy-fuel process can produce an HA-type coating; however, the process needs further optimization, specifically in the areas of coating-to-substrate bond strength and minimization of phases present other than HA, before it would be recommended for commercial use. PMID:7749000

  2. 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 all scaffolds supported proliferation of both cell types and deposition of calcified matrix, PU-HA composite fibres containing nano-HA enabled the highest cell viability and collagen deposition. These scaffolds have the potential to support bone matrix formation for bone tissue engineering. PMID:25117379

  3. Precision Extruding Deposition for Freeform Fabrication of PCL and PCL-HA Tissue Scaffolds

    NASA Astrophysics Data System (ADS)

    Shor, L.; Yildirim, E. D.; Güçeri, S.; Sun, W.

    Computer-aided tissue engineering approach was used to develop a novel Precision Extrusion Deposition (PED) process to directly fabricate Polycaprolactone (PCL) and composite PCL/Hydroxyapatite (PCL-HA) tissue scaffolds. The process optimization was carried out to fabricate both PCL and PCL-HA (25% concentration by weight of HA) with a controlled pore size and internal pore structure of the 0°/90° pattern. Two groups of scaffolds having 60 and 70% porosity and with pore sizes of 450 and 750 microns, respectively, were evaluated for their morphology and compressive properties using Scanning Electron Microscopy (SEM) and mechanical testing. The surface modification with plasma was conducted on PCL scaffold to increase the cellular attachment and proliferation. Our results suggested that inclusion of HA significantly increased the compressive modulus from 59 to 84 MPa for 60% porous scaffolds and from 30 to 76 MPa for 70% porous scaffolds. In vitro cell-scaffolds interaction study was carried out using primary fetal bovine osteoblasts to assess the feasibility of scaffolds for bone tissue engineering application. In addition, the results in surface hydrophilicity and roughness show that plasma surface modification can increase the hydrophilicity while introducing the nano-scale surface roughness on PCL surface. The cell proliferation and differentiation were calculated by Alamar Blue assay and by determining alkaline phosphatase activity. The osteoblasts were able to migrate and proliferate over the cultured time for both PCL as well as PCL-HA scaffolds. Our study demonstrated the viability of the PED process to the fabricate PCL and PCL-HA composite scaffolds having necessary mechanical property, structural integrity, controlled pore size and pore interconnectivity desired for bone tissue engineering.

  4. 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.

  5. 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.

  6. 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.

  7. Diffusion Flame Synthesis of Hydroxyapatite Nanoparticles using Urea Assisted Precursor Solution

    NASA Astrophysics Data System (ADS)

    Widiyastuti; Setiawan, Adhi; Setyawan, Heru; Kusdianto; Nurtono, Tantular; Nia, Suci Madha; Winardi, Sugeng

    2011-12-01

    Hydroxyapatite (HA) or (Ca10(PO4)6(OH)2 has been widely used in orthopedics and dental applications for human bone implant and teeth filler due to their biocompatibility and osteoconductive properties. Fine to nanoparticles of HA with appropriate stoichiometry and purity are preferred because they enhance densification and bioactive properties. Here, we reported the synthesis of hydroxyapatite particles in a diffusion flame reactor. LPG mainly consisting of butane and propane was used as fuel and compressed air was used as oxidizer and carrier gas. The effects of urea adding into precursor on morphology and crystallinity of the generated particles were investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe particles morphology and crystallinity, respectively. Purity of the generated particles was analyzed quantitatively from XRD pattern using Rietveld method. Spherical shape of particles morphology was obtained for particles synthesized without urea added into precursor. Increasing fuel flow rate and urea concentration led to further disintegration of the generated particles. Nano sized particles were generated using fuel flow rate of 1 L/min and 30 w% concentration of urea added into precursor. However, increasing urea concentration led to the increase of tricalcium phosphate as a further reaction of hydroxyapatite for flame generated by using LPG as fuel of 1 L/min.

  8. Effect of loading time on marginal bone loss around hydroxyapatite-coated implants

    PubMed Central

    Kim, Young-Kyun; Ahn, Kyo-Jin; Yun, Pil-Young; Kim, Minkyoung; Yang, Hong-So; Yi, Yang-Jin

    2013-01-01

    Objectives The objective of this study is compare the rate of marginal bone resorption around hydroxyapatite-coated implants given different loading times in order to evaluate their stability. Materials and Methods The study was conducted retrospectively for one year, targeting 41 patients whose treatment areas were the posterior maxilla and the mandible. Osstem TS III HA (Osstem Implant Co., Busan, Korea) and Zimmer TSV-HA (Zimmer Dental, Carlsbad, CA, USA), which employ the new hydroxyapatite coating technique, were used. The patients were divided into two groups - immediate and delayed loading - and the bone level at the time of loading commencement and after one year of loading was measured using periapical radiography. Differences between the groups were evaluated using Mann-Whitney (α=0.05). Results For all patients as a single group, the survival rate of the implants was 100%, and the mean marginal bone loss was 0.26±0.59 mm. In comparison of the differences by loading, mean marginal bone loss of 0.32±0.69 mm was recorded for the immediate loading group whereas the delayed loading group had mean marginal bone loss of 0.16±0.42 mm. However, the difference was not significant (P>0.05). Conclusion Within the limited observation period of one year, predictable survival rates can be expected when using immediately loaded hydroxyapatite-coated implants. PMID:24471037

  9. Physicochemical properties of the novel biphasic hydroxyapatite-magnesium phosphate biomaterial.

    PubMed

    Pijocha, Dawid; Zima, Aneta; Paszkiewicz, Zofia; Ślósarczyk, Anna

    2013-01-01

    Besides high-temperature calcium phosphates (CaPs), low-temperature calcium phosphate bone cements (CPCs), due to excellent biological properties: bioactivity, biocompability and osteoconductivity, are successfully used as bone substitutes. However, some disadvantages, related mainly to their low resorption rate and poor mechanical properties result in limited range of applications of these implant materials to non-loaded places in the skeletal system. To overcome this problem, magnesium phosphate cements (MPCs) with high strength have been considered as biomaterials. The main disadvantage of MPCs is that the acid-base setting reaction is an exothermic process that must be strictly controlled to avoid tissue necrosis. In this work, a new composite bone substitute (Hydroxyapatite Magnesium Phosphate Material - HMPM) based on hydroxyapatite (HA) and magnesium phosphate cement (MPC) with sodium pyrophosphate applied as a retardant of setting reaction was obtained. Its setting time was adequate for clinical applications. Combining properties of HA and MPC has made it possible to obtain microporous (showing bimodal pore size distribution in the range of 0.005-1.700 micrometers) potential implant material showing good surgical handiness and sufficient mechanical strength. Effectiveness of sodium pyrophosphate as a retardant of exothermic setting reaction of the new cement formulation was confirmed. After setting and hardening, the material consisted of hydroxyapatite and struvite as crystalline phases. Unreacted magnesium oxide was not detected. PMID:24215450

  10. 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. PMID:26652351

  11. The adsorptive behavior of albumin and lysozyme proteins on rod-shaped and plate-shaped hydroxyapatite.

    PubMed

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

    2013-01-01

    The adsorption behavior of albumin (BSA) and lysozyme (LSZ) on rod-shaped and plate-shaped hydroxyapatite (HA) was investigated to evaluate the influence of crystal orientation and morphology on the selective protein adsorption of HA. The rod-shaped HA was prepared by hydrothermal treatment from β-tricalcium phosphate (β-TCP) in H3PO4 solution (pH 2.0 and 4.0 for HA-pH 2.0 and HA-pH 4.0). The plate-shaped HA was synthesized by hydrolysis of CaHPO4-2H2O (DCPD) in NaOH solution at 40°C and 80°C (HA-40°C and HA-80°C). The synthesized HA was characterized using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). HA-pH 2.0 and HA-pH 4.0 produced rod-shaped crystals that were highly oriented to the a-face plane, whereas HA-40°C and HA-80°C showed a plate-like shape and a c-face preferred orientation. The peak intensity ratio I(300)/I(002) (a/c intensity ratio) from the XRD patterns increased in the following order: HA-80°C, HA-40°C, HA-pH 2.0 and HA-pH 4.0. It also increased as the Ca/P ratio decreased. The amount of adsorbed BSA increased in the following order: HA-pH 4.0, HA-pH 2.0, HA-40°C and HA-80°C. The amount of adsorbed LSZ on HA increased in the following order--HA-pH 2.0, HA-pH 4.0, HA-40°C and HA-80°C--with a corresponding decrease in the a/c intensity ratio. The BSA/LSA adsorption ratio increased with the a/c intensity ratio in the range of 3.3-8.9, and the BSA and LSZ were selectively adsorbed on HA, depending on the crystal shape. PMID:23629536

  12. Functionalization of polycaprolactone/hydroxyapatite scaffolds with Usnea lethariiformis extract by using supercritical CO2.

    PubMed

    Fanovich, M A; Ivanovic, J; Zizovic, I; Misic, D; Jaeger, P

    2016-01-01

    Investigation of an integrated supercritical fluid extraction and supercritical solvent impregnation process for fabrication of microporous polycaprolactone-hydroxyapatite (PCL-HA) scaffolds with antibacterial activity is presented. The HA content and particle size as well as the operating conditions of the integrated process is optimized regarding the amount of impregnated antibacterial agent (Usnea lethariiformis extract) in the PCL-HA matrix, scaffold morphology and antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) strains. High pressure differential scanning calorimetry (HP-DSC) assay reveals that an increasing amount of HA results in decreasing melting temperature as well as crystallinity at an operating pressure of 17 MPa. The PCL-HA composites with micrometric sizes of the HA particles are convenient for being processed by the integrated process due to the simple preparation, a good interaction between the PCL matrix and filler and the advantageous impact on sorption. The scaffold obtained from PCL-HA with 20% of the HA shows the highest impregnation yield at 17 MPa and 35 °C (5.9%) and subsequently also the best bactericidal effect on the tested MRSA strains at an initial bacterial inoculum of 2 × 10(-4)CFU/mL. PMID:26478304

  13. Hydroxyapatite crystallinity does not affect the repair of critical size bone defects

    PubMed Central

    CONZ, Marcio Baltazar; GRANJEIRO, José Mauro; SOARES, Gloria de Almeida

    2011-01-01

    Objective The physicochemical properties of hydroxyapatite (HA) granules were observed to affect the biological behavior of graft materials. The aim of this work was to analyze the tissue response of two HA granules with different crystallinity and Ca/P ratio in vivo. Material and Methods The HA granules were produced in the Biomaterials Laboratory (COPPE/UFRJ). The testing materials were HA granules presenting a Ca/P molar ratio of 1.60 and 28% crystallinity (HA-1), and a Ca/P molar ratio of 1.67 and 70% crystallinity (HA-2). Both HAs were implanted into a critical-size calvaria rat defects. Results To note, in the control group, the bone defects were filled with blood clot only. Descriptive and histomorphometric analyses after 1, 3, and 6 months postoperatively showed mild inflammatory infiltrate, mainly comprising macrophage-like and multinucleated giant cells, and an increase in the volume density of the fibrous tissues (p<0.05), which was in contrast to the similar volume density of the newly formed bone and biomaterials in relation to the control group. Conclusion Thus, we concluded that HA-1 and HA-2 are biocompatible and non-degradable, and that crystallinity does not affect bone repair of critical size defects. PMID:21655775

  14. Physical Properties and Cellular Responses to Crosslinkable Poly(Propylene Fumarate)/Hydroxyapatite Nanocomposites

    PubMed Central

    Lee, Kee-Won; Wang, Shanfeng; Yaszemski, Michael J.; Lu, Lichun

    2008-01-01

    A series of crosslinkable nanocomposites has been developed using hydroxyapatite (HA) nanoparticles and poly(propylene fumarate) (PPF). PPF/HA nanocomposites with four different weight fractions of HA nanoparticles have been characterized in terms of thermal and mechanical properties. To assess surface chemistry of crosslinked PPF/HA nanocomposites, their hydrophilicity and capability of adsorbing proteins have been determined using static contact angle measurement and MicroBCA protein assay kit after incubation with 10% fetal bovine serum (FBS), respectively. In vitro cell studies have been performed using MC3T3-E1 mouse pre-osteoblast cells to investigate the ability of PPF/HA nanocomposites to support cell attachment, spreading, and proliferation after 1, 4, and 7 days. By adding HA nanoparticles to PPF, the mechanical properties of crosslinked PPF/HA nanocomposites have not been increased due to the initially high modulus of crosslinked PPF. However, hydrophilicity and serum protein adsorption on the surface of nanocomposites have been significantly increased, resulting in enhanced cell attachment, spreading, and proliferation after 4 days of cell seeding. These results indicate that crosslinkable PPF/HA nanocomposites are useful for hard tissue replacement because of excellent mechanical strength and osteoconductivity. PMID:18403013

  15. Synthesis, characterization and modelling of zinc and silicate co-substituted hydroxyapatite.

    PubMed

    Friederichs, Robert J; Chappell, Helen F; Shepherd, David V; Best, Serena M

    2015-07-01

    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

  16. 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.

  17. Preparation and Characterization of Lanthanum-Incorporated Hydroxyapatite Coatings on Titanium Substrates.

    PubMed

    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

  18. Increased osteoblast adhesion on nanograined hydroxyapatite and tricalcium phosphate containing calcium titanate.

    PubMed

    Ergun, Celaletdin; Liu, Huinan; Halloran, John W; Webster, Thomas J

    2007-03-15

    Depending on the coating method utilized and subsequent heat treatments (such as through the use of plasma-spray deposition), inter-diffusion of atomic species across titanium (Ti) and hydroxyapatite (HA) coatings may result. These events may lead to structural and compositional changes that consequently cause unanticipated HA phase transformations which may clearly influence the performance of an orthopedic implant. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), HA doped with Ti, and those containing calcium titanate (CaTiO(3)). In doing so, results of this study showed that osteoblast (bone-forming cells) adhesion increased with greater CaTiO(3) substitutions in either HA or TCP. Specifically, osteoblast adhesion on HA and TCP composites with CaTiO(3) was almost 4.5 times higher than that over pure HA. Material characterization studies revealed that enhanced osteoblast adhesion on these compacts may be due to increasing shrinkage in the unit lattice parameters and decreasing grain size. Although all CaTiO(3) composites exhibited excellent osteoblast adhesion results, Ca(9)HPO(4)(PO(4))(5)OH phase transformation into TCP/CaTiO(3) increased osteoblast adhesion the most; because of these reasons, these materials should be further studied for orthopedic applications. PMID:17120201

  19. 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

  20. Composite nanofiber mats consisting of hydroxyapatite and titania for biomedical applications.

    PubMed

    Kim, Hong Mi; Chae, Won-Pyo; Chang, Ki-Whan; Chun, Sungsu; Kim, Sukyoung; Jeong, Yongsoo; Kang, Inn-Kyu

    2010-08-01

    Composite nanofiber mats (HA/TiO2) consisting of hydroxyapatite (HA) and titania (TiO2) were fabricated via an electrospinning technique and then collagen (type I) was immobilized on the surface of the HA/TiO2 composite nanofiber mat to improve tissue compatibility. The structure and morphology of the collagen-immobilized composite nanofiber mat (HA/TiO2-col) was investigated using an X-ray diffractometer, electron spectroscopy for chemical analysis, and scanning electron microscope. The potential of the HA/TiO2-col composite nanofiber mat for use as a bone scaffold was assessed by an experiment with osteoblastic cells (MC3T3-E1) in terms of cell adhesion, proliferation, and differentiation. The results showed that the HA/TiO2-col composite nanofiber mats possess better cell adhesion and significantly higher proliferation and differentiation than untreated HA/TiO2 composite nanofiber mats. This result suggests that the HA/TiO2-col composite nanofiber mat has a high-potential for use in the field of bone regeneration and tissue engineering. PMID:20574975

  1. 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

  2. Effect of hydroxyapatite nanocrystals functionalized with lactoferrin in osteogenic differentiation of mesenchymal stem cells.

    PubMed

    Montesi, Monica; Panseri, Silvia; Iafisco, Michele; Adamiano, Alessio; Tampieri, Anna

    2015-01-01

    Lactoferrin (LF) is a bioactive glycoprotein that became recently interesting in the field of bone regeneration for its modulatory effect on bone cells. On the basis of this evidence this work aims to functionalize biomimetic hydroxyapatite (HA) nanocrystals with LF to study their effect on osteogenic differentiation of mesenchymal stem cells (MSCs). The orientation of LF on the HA surface was analyzed by spectroscopic and thermal techniques. Three samples with different amounts of LF attached to HA nanocrystals were tested in vitro. The combined effect of HA and LF on MSC proliferation and morphology, alkaline phosphatase (ALP) activity, and gene expression were evaluated at different time points. The sample with the lowest LF amount showed the best bioactivity probably due to the formation of a single layer of protein with a better molecular orientation. Coupling of HA-LF did not affect cell proliferation and morphology, while analysis of HA-LF on ALP activity and messenger RNA expression of the selected genes, demonstrated the role of HA-LF in the induction of osteogenic markers. HA-LF represents a promising system to be used to manufacture bioactive functional materials in tissue engineering (as scaffolds, injectable cements, or coatings for metallic implants) with enhanced anabolic activity to treat bone diseases. PMID:24639083

  3. Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite.

    PubMed

    Parente, P; Savoini, B; Ferrari, B; Monge, M A; Pareja, R; Sanchez-Herencia, A J

    2013-03-01

    The capability of the colloidal method to produce yttria (Y(2)O(3)) dispersed hydroxyapatite (HA) has been investigated as an alternative method to the conventional method of mechanical mixing and sintering for developing HA-based materials that could exhibit controllable and enhanced functional properties. A water based colloidal route to produce HA materials with highly dispersed Y(2)O(3) has been applied, and the effect of 10 wt.% Y(2)O(3) addition to HA investigated by thermal analysis, X-ray diffraction and Fourier transform infrared spectroscopy. These measurements evidence a remarkable effect of this Y(2)O(3) addition on decomposition mechanisms of synthetic HA. Results show that incorporation of Y(2)O(3) as dispersed second phase is beneficial because it hinders the decomposition mechanisms of HA into calcium phosphates. This retardation will allow the control of the sintering conditions for developing HA implants with improved properties. Besides, substitution of Ca(2+) with Y(3+) ions appears to promote the formation of OH(-) vacancies, which could improve the conductive properties of HA favorable to osseointegration. PMID:25427499

  4. X-ray peak broadening studies of nanocrystalline hydroxyapatite by Williamson-Hall analysis

    NASA Astrophysics Data System (ADS)

    Venkateswarlu, K.; Chandra Bose, A.; Rameshbabu, N.

    2010-10-01

    Hydroxyapatite (HA) nanoparticles were prepared by microwave synthesis method and the obtained powder is annealed at 800 °C for 2 h. The annealed HA particles were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy methods. The HA size and morphology were examined using a transmission electron microscope (TEM). The XRD results reveal that the diffraction peaks of the annealed HA were of well crystalline and correspond to the hexagonal crystal structure. The XRD and FTIR results confirm the absence of secondary phases such as β-tricalcium phosphate (β-TCP) and calcium oxide in annealed HA particles. The TEM result confirms the hexagonal structure of annealed HA and the particles were observed to be of ellipsoid-like shaped morphology with less agglomeration. The lattice strain, crystallite size, lattice deformation stress and deformation energy density for annealed (800 °C) HA nanoparticles were estimated by Williamson-Hall-isotropic strain model ( W- H-ISM), W-H-anisotropic strain model ( W- H-ASM) and W-H-energy density model ( W- H-EDM) based on Williamson-Hall ( W- H) plot from powder X-ray diffraction data. The results of estimated average crystallite size of annealed HA by Scherrer and W- H plot methods were compared with TEM results. It is found that the average crystallite size measured by W- H plot methods is in good agreement with TEM results.

  5. Adsorptive removal of Pb(II) from aqueous solution using nano-sized hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Ramesh, S. T.; Rameshbabu, N.; Gandhimathi, R.; Srikanth Kumar, M.; Nidheesh, P. V.

    2013-03-01

    This study investigated the sorption of Pb(II) in aqueous solution onto hydroxyapatite (HA) surfaces. Batch experiments were carried out using synthetic HA. The effect of contact time, HA dosage, and initial pH on removal efficiency were also investigated. The adsorption equilibrium and kinetics of Pb(II) on this adsorbent were then examined at 25 C. Kinetic data were analyzed by pseudo first, second, and intra-particle diffusion models. The sorption data were then correlated with the Langmuir, Freundlich, Halsey, and Harkins-Jura adsorption isotherm models. The optimum dose of HA for Pb(II) removal is found to be 0.12 g/l with the removal efficiency of 97.3 % at an equilibrium contact time of 1 h. It is found that the adsorption kinetics of the Pb(II) on HA follow the pseudo second-order reaction. All the isotherms fitted well for experimental data. Capacity of HA is found as 357.14 mg Pb(II)/g of HA. The Pb(II) immobilization mechanism was studied. The results indicated that HA can be used as an effective adsorbent for removal of Pb(II) from aqueous solution.

  6. Solvothermal synthesis of three-dimensional microspherical bismuth oxychloride self-assembled by microspheres

    NASA Astrophysics Data System (ADS)

    Li, Tengfei; Lin, Liyang; Wei, Hongmei; Liang, Guoqiang; Kuang, Xinliang; Liu, Tianmo

    2016-02-01

    Uniform BiOCl microspheres have been synthesized via a facile solvothermal route. The structural features of the as-prepared BiOCl samples were systematically characterized by the X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The SEM characterization results indicated that BiOCl microspheres possessed a superstructure composed of several hierarchical microspheres, which were assembled by numerous two dimensional nanosheets. This kind of special BiOCl 3D microstructure exhibited a large BET surface area of about 14.24 m2 g-1. Besides, the photocatalytic properties of BiOCl hollow microsphere sample and sheet-like sample were investigated in detail. Significantly, BiOCl hollow microsphere sample presented faster degradation rate toward RhB even under visible light, which should be attributed to the unique BiOCl nanosheets self-assembled hollow microspheres.

  7. Confocal Raman and electronic microscopy studies on the topotactic conversion of calcium carbonate from Pomacea lineate shells into hydroxyapatite bioceramic materials in phosphate media.

    PubMed

    dePaula, S M; Huila, M F G; Araki, K; Toma, H E

    2010-12-01

    Conversion of Pomacea lineate shells into hydroxyapatite (HA) bioceramic materials was investigated by their in vitro treatment with phosphate solutions, at room temperature. Confocal Raman microscopy revealed that the conversion proceeds at distinct rates through the nacreous or periostracum sides of the shell. The conversion can be accelerated using powdered samples, yielding biocompatible materials of great interest in biomedicine. PMID:20678941

  8. Seeing is believing, PLGA microsphere degradation revealed in PLGA microsphere/PVA hydrogel composites.

    PubMed

    Gu, Bing; Sun, Xuanhao; Papadimitrakopoulos, Fotios; Burgess, Diane J

    2016-04-28

    The aim of this study was to understand the polymer degradation and drug release mechanism from PLGA microspheres embedded in a PVA hydrogel. Two types of microspheres were prepared with different molecular weight PLGA polymers (approximately 25 and 7kDa) to achieve different drug release profiles, with a 9-day lag phase and without a lag phase, respectively. The kinetics of water uptake into the microspheres coincided with the drug release profiles for both formulations. For the 25kDa microspheres, minimal water uptake was observed in the early part of the lag phase followed by substantial water uptake at the later stages and in the drug release phase. For the 7kDa microspheres, water uptake occurred simultaneously with drug release. Water uptake was approximately 2-3 times that of the initial microsphere weight for both formulations. The internal structure of the PLGA microspheres was evaluated using low temperature scanning electron microscopy (cryo-SEM). Burst drug release occurred followed by pore forming from the exterior to the core of both microspheres. A well-defined hydrogel/microsphere interface was observed. For the 25kDa microspheres, internal pore formation and swelling occurred before the second drug release phase. The surface layer of the microspheres remained intact whereas swelling, and degradation of the core continued throughout the drug release period. In addition, microsphere swelling reduced glucose transport through the coatings in PBS media and this was considered to be a as a consequence of the increased thickness of the coatings. The combination of the swelling and microdialysis results provides a fresh understanding on the competing processes affecting molecular transport of bioanalytes (i.e. glucose) through these composite coatings during prolonged exposure in PBS. PMID:26965956

  9. The importance of amino acid interactions in the crystallization of hydroxyapatite

    PubMed Central

    Jahromi, M. Tavafoghi; Yao, G.; Cerruti, M.

    2013-01-01

    Non-collagenous proteins (NCPs) inhibit hydroxyapatite (HA; Ca5(PO4)3OH) formation in living organisms by binding to nascent nuclei of HA and preventing their further growth. Polar and charged amino acids (AAs) are highly expressed in NCPs, and the negatively charged ones, such as glutamic acid (Glu) and phosphoserine (P-Ser) seem to be mainly responsible for the inhibitory effect of NCPs. Despite the recognized importance of these AAs on the behaviour of NCPs, their specific effect on HA crystallization is still unclear, and controversial results have been reported concerning the efficacy of HA inhibition of positively versus negatively charged AAs. We focused on a positively charged (arginine, Arg) and a negatively charged (Glu) AA, and their combination in the same solution. We studied their inhibitory effect on HA nucleation and growth at physiological temperature and pH and we determined the mechanism by which they can affect HA crystallization. Our results showed a strong inhibitory effect of Arg on HA nucleation; however, Glu was more effective in inhibiting HA crystal growth during the growth stage. The combination of Glu and Arg was less effective in controlling HA nucleation, but it inhibited HA crystal growth. We attributed these differences to the stability of complexes formed between AAs and calcium and phosphate ions at the nucleation stage, and in bonding strength of AAs to HA crystal faces during the growth stage. The AAs also influenced the morphology of synthesized HA. Presence of either Arg or Glu resulted in the formation of spherulites consisting of preferentially oriented nanoplatelets orientation. This was attributed to kinetic factors favoring growth front nucleation (GFN) mechanism. PMID:23269851

  10. Titania-hydroxyapatite nanocomposite coatings support human mesenchymal stem cells osteogenic differentiation.

    PubMed

    Dimitrievska, Sashka; Bureau, Martin N; Antoniou, John; Mwale, Fackson; Petit, Alain; Lima, Rogerio S; Marple, Basil R

    2011-09-15

    In addition to mechanical and chemical stability, the third design goal of the ideal bone-implant coating is the ability to support osteogenic differentiation of mesenchymal stem cells (MSCs). Plasma-sprayed TiO(2)-based bone-implant coatings exhibit excellent long-term mechanical properties, but their applications in bone implants are limited by their bioinertness. We have successfully produced a TiO(2) nanostructured (grain size <50 nm) based coating charged with 10% wt hydroxyapatite (TiO(2)-HA) sprayed by high-velocity oxy-fuel. On Ti64 substrates, the novel TiO(2)-HA coating bond 153× stronger and has a cohesive strength 4× higher than HA coatings. The HA micro- and nano-sized particles covering the TiO(2)-HA coating surface are chemically bound to the TiO(2) coating matrix, producing chemically stable coatings under high mechanical solicitations. In this study, we elucidated the TiO(2)-HA nanocomposite coating surface chemistry, and in vitro osteoinductive potential by culturing human MSCs (hMSCs) in basal and in osteogenic medium (hMSC-ob). We assessed the following hMSCs and hMSC-ob parameters over a 3-week period: (i) proliferation; (ii) cytoskeleton organization and cell-substrate adhesion; (iii) coating-cellular interaction morphology and growth; and (iv) cellular mineralization. The TiO(2) -HA nanocomposite coatings demonstrated 3× higher hydrophilicity than HA coatings, a TiO(2)-nanostructured surface in addition to the chemically bound HA micron- and nano-sized rod to the surface. hMSCs and hMSC-ob demonstrated increased proliferation and osteoblastic differentiation on the nanostructured TiO(2)-HA coatings, suggesting the TiO(2)-HA coatings nanostructure surface properties induce osteogenic differentiation of hMSC and support hMSC-ob osteogenic potential better than our current golden standard HA coating. PMID:21702080

  11. SRNL POROUS WALL GLASS MICROSPHERES

    SciTech Connect

    Wicks, G; Leung Heung, L; Ray Schumacher, R

    2008-04-15

    The Savannah River National Laboratory (SRNL) has developed a new medium for storage of hydrogen and other gases. This involves fabrication of thin, Porous Walled, Hollow Glass Microspheres (PW-HGMs), with diameters generally in the range of 1 to several hundred microns. What is unique about the glass microballons is that porosity has been induced and controlled within the thin, one micron thick walls, on the scale of 10 to several thousand Angstroms. This porosity results in interesting properties including the ability to use these channels to fill the microballons with special absorbents and other materials, thus providing a contained environment even for reactive species. Gases can now enter the microspheres and be retained on the absorbents, resulting in solid-state and contained storage of even reactive species. Also, the porosity can be altered and controlled in various ways, and even used to filter mixed gas streams within a system. SRNL is involved in about a half dozen different programs involving these PW-HGMs and an overview of some of these activities and results emerging are presented.

  12. 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.

  13. 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.

  14. 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. PMID:21514799

  15. 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 HA15% and HA50% groups, despite the similar value of bone volume rate in fusion mass among the three HA groups. In the HA85% group, bone ingrowth was achieved throughout the implanted HAs via interconnecting pores and there was excellent unification between the HA granules and the newly mineralized bone. On the other hand, in the non-interconnected porous HA groups, only a little bone ingrowth could be seen at the peripheral pores of the implanted HA, and its surface was mostly covered with fibrous tissue or empty space. The current study demonstrated that the HA porous characteristics had an effect on the histological outcomes in a rabbit PLF model. We would like to conclude that the interconnected high porous structure seems to be promising for the environment of PLF in the point of producing fusion mass with higher cellular viability. This is because the HA85% is superior in terms of integration with the newly formed bone in fusion mass compared to the non-interconnected porous HAs. However, the porous modifications of HA have little influence on fusion rate and mechanical strength because primary stabilization of the fusion segment is mainly achieved by bridging bone between the adjacent transverse processes outside the implanted materials, rather than the degree of integration between the newly formed bone and the HA granules in PLF. PMID:17891422

  16. 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

  17. Structure, mechanical property and corrosion behaviors of (HA+β-TCP)/Mg-5Sn composite with interpenetrating networks.

    PubMed

    Wang, X; Li, J T; Xie, M Y; Qu, L J; Zhang, P; Li, X L

    2015-11-01

    In this paper, a novel (Hydroxyapatite+β-tricalcium phosphate)/Mg-5Sn ((HA+β-TCP)/Mg-5Sn) composite with interpenetrating networks was fabricated by infiltrating Mg-5Sn alloy into porous HA+β-TCP using suction casting technique. The structure, mechanical property and corrosion behaviors of the composite have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion test. It is shown that the molten Mg-5Sn alloy has infiltrated not only into the pores but also into the struts of the HA+β-TCP scaffold to forming a compact composite. The microstructure observation also shows that the Mg alloy contacts to the HA+β-TCP closely, and no reaction layer can be found between Mg-5Sn alloy and scaffold. The ultimate compressive strength of the composite is as high as 176MPa, which is about four fifths of the strength of the Mg-5Sn bulk alloy. The electrochemical and immersion tests indicate that the corrosion resistance of the composite is better than that of the Mg-5Sn bulk alloy. The corrosion products on the composite surface are mainly Mg(OH)2, Ca3(PO4)2 and HA. Appropriate mechanical and corrosion properties of the (HA+β-TCP)/Mg-5Sn composite indicate its possibility for new bone tissue implant materials. PMID:26249605

  18. Adhesion strength characterization of PVDF/HA coating on cp Ti surface modified by laser beam irradiation

    NASA Astrophysics Data System (ADS)

    Ribeiro, A. A.; Vaz, L. G.; Guastaldi, A. C.; Campos, J. S. C.

    2012-10-01

    Up to the moment, there is no standardized test for measuring the adhesion strength of polymeric coatings on titanium substrate modified by laser beam irradiation. The present work aimed to assess the adhesion strength of polyvinylidene fluoride (α-PVDF)/hydroxyapatite (HA) composite coating on commercially pure titanium (α-cp Ti) substrate surface modified by laser beam irradiation, using the three-point bending test. The preparation of coating was carried out by mixing α-PVDF pellets dissolved in dimethylacetamide (DMA) with HA/DMA emulsion. The mixture was poured onto the α-cp Ti sample and left to dry in an oven. Commercially pure titanium plates were coated with α-PVDF/HA composite film, in proportions of 100/00 (PVDF) and 60/40 (PVDF/HA) in weight. The Ti-PVDF/HA samples were subjected to the three-point bending test and analyzed by scanning electron microscopy. According to the results, PVDF and PVDF/HA coatings showed a good adhesion strength on α-cp Ti surface, since no detachment was observed.

  19. Effects of the nano-tubular anodic TiO2 buffer layer on bioactive hydroxyapatite coating.

    PubMed

    Piao, Zhonglie; Qiu, Jijun; Wu, Yongqing; Park, Se-Jeong; He, Weizhen; Timur, A; Ryu, Su-Chak; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2011-01-01

    We studied the effect of nano-tubular anodic TiO2 buffer layers on hydroxyapatite (HA) coating. The pulsed laser deposition (PLD) method was used to deposit HA on a well arranged nano-tubular anodic TiO2 (NT-ATO) buffer layer prepared by an electrochemical anodization technique. The surface morphology and chemical composition of HA coatings were characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and contact angle measurement. We found that crystalline HA coatings show well arranged porous morphologies with a favorable surface wettability. We also found that an anodic nano-tubular TiO2 buffer layer with a relatively short tube length shows a better coating morphology. The deposition process of HA on the nanotubular TiO2 buffer layer was also proposed. PMID:21446441

  20. 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. PMID:25910818

  1. X-ray photo-emission and energy dispersive spectroscopy of HA coated titanium

    SciTech Connect

    Drummond, J.L.; Steinberg, A.D.; Krauss, A.R.

    1997-08-01

    The purpose of this study was to determine the chemical composition changes of hydroxyapatite (HA) coated titanium using surface analysis (x-ray photo-emission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls, 30 minutes and 3 hours aged specimens in distilled water or 0.2M sodium phosphate buffer (pH 7.2) at room temperature. Each x-ray photo-emission cycle consisted of 3 scans followed by argon sputtering for 10 minutes for a total of usually 20 cycles, corresponding to a sampling depth of {approximately} 1500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {mu}m area for 500 sec. Scanning electron microscopy examination showed crystal formation (3P{sub 2}O{sub 5}*2CAO*?H{sub 2}O by energy dispersive spectroscopy analysis) on the HA coating for the specimens aged in sodium phosphate buffer. The x-ray photo-emission results indicated the oxidation effect of water on the titanium (as TiO{sub 2}) and the effect of the buffer to increase the surface concentration of phosphorous. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis. The crystal growth was only observed for the sodium phosphate buffer specimens and only on the HA surface.

  2. Radio frequency (rf) plasma spheroidized HA powders: powder characterization and spark plasma sintering behavior.

    PubMed

    Xu, J L; Khor, K A; Gu, Y W; Kumar, R; Cheang, P

    2005-05-01

    The present study describes the synthesis of spheroidized hydroxyapatite (HA) powders using a radio frequency (rf) inductively coupled plasma (ICP) torch. The spheroidized powders were consolidated through a spark plasma sintering (SPS) system. The microstructure and crystallographic phases in the synthesized powders were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectrometry. Results showed that the HA feedstock decomposed after rf plasma processing. Crystalline HA, alpha-tri-calcium phosphate (alpha-TCP), tetra-calcium phosphate (TTCP) and calcium oxide (CaO) were detected in the plasma-spheroidized powders. Raman spectra results indicated strong presence of amorphous calcium phosphate (ACP) in the spheroidized powders. The particle size distribution and specific surface area were influenced through the rf plasma working plate power levels. The sintering behavior of the rf plasma synthesized powders was analyzed through the SPS process and the results indicated that the spheroidized powders commence sintering at approximately 900 degrees C and through to 1150 degrees C. After sintering above 1100 degrees C for 3min, the relative densities of the SPS compacts reached 96% of the theoretical value. The SPS compacts were immersed in simulated body fluids (SBF) for different durations and the results confirmed their bioactivities. PMID:15585221

  3. 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.

  4. 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.

  5. 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.

  6. Significance of melt-fraction in HVOF sprayed hydroxyapatite particles, splats and coatings.

    PubMed

    Khor, K A; Li, H; Cheang, P

    2004-01-01

    Microstructure characterization and property evaluation of high velocity oxy-fuel (HVOF) sprayed hydroxyapatite (HA) splats and coatings were conducted in the present study as a function of the proportion of melting that occurred in HA particles during HVOF spray. In vitro behavior of single and folded HA splats in simulated body fluid was also investigated. Results showed that phase composition of as-sprayed HA coatings was influenced significantly by the melt fraction in HVOF sprayed particles. Melt fraction of the HA powders were experimentally determined from particle morphology analysis. It was found that the spray parameters and starting powder size influenced the melt fraction of the particles. In vitro investigation of individual HA splats made from different HA particles revealed decisive role of local phase composition in influencing their dissolution/precipitation behavior during the test. Furthermore, Raman spectroscopy qualitative inspection on the sprayed HA particles (partial melted) revealed that thermal decomposition occurred within the melted part rather than the unmelted zone. Young's modulus and micro-hardness of the as-sprayed particles and coatings were determined using nano-indentation technique. The resolidified zone of the sprayed HA particles exhibited an average Young's modulus value of 41.25 GPa. The measured values ranged from 23.1 to 65.3 GPa. The unmelted part of the HA powders showed a markedly narrower range. Young's modulus value of 83.9 GPa (+/-9.4 GPa) was recorded for this region. This succinctly highlight the difference between the unmelted region and melted regions of a HA particle. Young's moduli values measured on HVOF coatings were found to mirror the trend found in the spheroidised particles and splats with apt fidelity. PMID:14643591

  7. Measurement of extent of bone ongrowth and hydroxyapatite absorption in retrieved acetabular cups.

    TOXLINE Toxicology Bibliographic Information

    Chung YY; Kim J; Lim CH; Kim KS; Lee YS

    2008-05-01

    BACKGROUND: To understand why hydroxyapatite (HA)-coated acetabular cups did not produce satisfactory results, we measured the extent of bone ongrowth and HA absorption of the retrieved cups.METHODS: Between March 1992 and June 1998, a total of 289 patients underwent total hip arthroplasty with an HA-coated ABG (Anatomical Benoist Giraud) prosthesis in our hospital. We revised 71 cups in our hospital, 43 of which were included in this study. The cups were in situ for an average of 80.4 months. We revised 21 cups for polyethylene wear and osteolysis, 20 for loosening, and 2 for recurrent dislocation. The outer surfaces of the cups were subdivided by two circular grooves into three areas: central, middle, peripheral. Bone ongrowth and HA absorption was measured in terms of area and thickness. The areas were graphically calculated using a computer imaging analysis system. The thickness of the HA coating remaining on the retrieved cup was measured by an x-ray coating thickness measurement instrument.RESULTS: Of the 43 cups, 37 had bone ongrowth. Bone ongrowth was observed on the central surface in 23 cups, on the middle surface in 27 cups, and on the peripheral surface in 15 cups; 6 of the 37 cups had bone ongrowth only in the groove. Altogether, 37 cups showed bone ongrowth on 6.43% of the outer acetabular surface. HA absorption appeared in all 43 cups, and an average 63.21% of the HA coating area was absorbed. there was a proportional relation between the rate of HA absorption and implantation duration, but there was no consistent trend between the thickness of the HA coating and implantation duration.CONCLUSIONS: We suggest that progressive HA absorption and minimal bone ongrowth are related to the failure of HA-coated acetabular cups at long-term follow-up after total hip arthroplasty.

  8. Stimulatory effect of hydrothermally synthesized biodegradable hydroxyapatite granules on osteogenesis and direct association with osteoclasts.

    PubMed

    Gonda, Yoshinori; Ioku, Koji; Shibata, Yasuaki; Okuda, Takatoshi; Kawachi, Giichiro; Kamitakahara, Masanobu; Murayama, Hisashi; Hideshima, Katsumi; Kamihira, Shimeru; Yonezawa, Ikuho; Kurosawa, Hisashi; Ikeda, Tohru

    2009-09-01

    Calcium-deficient hydroxyapatite (HA) granules with a unique spherical shape were prepared using an applied hydrothermal method. Spherical stoichiometric HA granules were also prepared by normal sintering and both granules were used for implantation into rat tibiae to compare the biological responses to each implant. Twelve and 24 weeks after implantation, the volume of calcium-deficient HA granules was significantly less than that of stoichiometric HA granules, and the biodegradability of calcium-deficient HA granules was confirmed. The larger number of osteoclasts, larger osteoblast surface and larger bone volume in the implanted area of calcium-deficient HA than those of stoichiometric HA suggested that osteoclastic resorption of calcium-deficient HA affected osteogenesis in that area. To analyze the direct contribution of osteoclasts to osteogenesis, C2C12 multipotent myoblastic cells, which have the potential to differentiate into osteoblasts in the presence of bone morphogenetic protein 2, were cultured with supernatants of osteoclasts cultured on calcium-deficient HA, stoichiometric HA, beta-tricalcium phosphate disks or plastic dishes, or bone marrow macrophages cultured on plastic dishes. Supernatants of osteoclasts but not bone marrow macrophages stimulated the expression of Runx2 and osteocalcin in C2C12 cells in concert with bone morphogenetic protein 2. The expression of alkaline phosphatase was stimulated with supernatants of osteoclasts cultured on ceramic disks. These results suggested that osteoclasts produced certain soluble factors which stimulated osteoblastic differentiation and they were thought to be associated with the induction of a larger osteoblast surface and bone volume in the animals implanted with calcium-deficient HA granules. PMID:19481798

  9. Biomimetic and cell-mediated mineralization of hydroxyapatite by carrageenan functionalized graphene oxide.

    PubMed

    Liu, Hongyan; Cheng, Ju; Chen, Fengjuan; Hou, Fengping; Bai, Decheng; Xi, Pinxian; Zeng, Zhengzhi

    2014-03-12

    In bone tissue engineering, it is imperative to design multifunctional biomaterials that can induce and assemble bonelike apatite that is close to natural bone. In this study, graphene oxide (GO) was functionalized by carrageenan. The resulting GO-carrageenan (GO-Car) composite was further used as a substrate for biomimetic and cell-mediated mineralization of hydroxyapatite (HA). It was confirmed that carrageenan on the GO surface facilitated the nucleation of HA. The observation of the effect of the GO-Car on the adhesion, morphology, and proliferation of MC3T3-E1 cells was investigated. In vitro studies clearly show the effectiveness of GO-Car in promoting HA mineralization and cell differentiation. The results of this study suggested that the GO-Car hybrid will be a promising material for bone regeneration and implantation. PMID:24527702

  10. 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. PMID:24554305

  11. 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 m 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

  12. Postoperative lumbar spinal stenosis after intertransverse fusion with granules of hydroxyapatite: a case report

    PubMed Central

    2012-01-01

    In the present case of postoperative lumbar spinal stenosis after non-instrumented intertransverse fusion with granules of hydroxyapatite (HA), bone union was not completed and the patient felt the recurrence of his symptoms within two years. We performed re-decompression with fusion, and in hematoxylin and eosin staining of HA granulation harvested during revision surgery, fibrous tissue with hyaline degeneration surrounded the cavity where the HA had existed. Multinuclear giant cells and lymphocytes infiltrated some parts of the marginal layer of the cavity, and no obvious bony bridge had regenerated from autologous bone. No tartrate-resistant acid phosphate (TRAP) -positive osteoclasts could be seen in the new bone, suggesting that the activity of osteoclasts in the new bone decreased during the seven years after the primary surgery. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3483360258050263 PMID:23134668

  13. 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.

  14. Orientation-Selective Alignments of Hydroxyapatite Nanoblocks through Epitaxial Attachment in a and c Directions.

    PubMed

    Nakamura, Kazuki; Nakagawa, Yoshitaka; Kageyama, Hiroyuki; Oaki, Yuya; Imai, Hiroaki

    2016-04-26

    Nanometric rods of hydroxyapatite (HA) were aligned in selective crystallographic directions by the alternation of adsorbing molecules. The side and end faces of HA nanorods elongated in the c direction were covered with oleic acid (OA) and tetraoctylammonium (TOA) ions, respectively. Alignment in the c direction of the OA-modified nanorods was produced through epitaxial attachment of the bare end faces in toluene because the side faces were hydrophobized with the negatively charged modifier. Another alignment-in the a direction of the TOA-modified HA nanorods-was obtained through the epitaxial attachment of the bare side faces in ethanol due to stabilization of the end faces with the positively charged modifier. Controlled alignments of the nanorods in the a and c directions were achieved through oriented attachment with the selective coverage of the c and a faces with the specific modifiers. PMID:27078749

  15. 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.

  16. 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. PMID:26758895

  17. Method for introduction of gases into microspheres

    DOEpatents

    Hendricks, Charles D.; Koo, Jackson C.; Rosencwaig, Allan

    1981-01-01

    A method for producing small hollow glass spheres filled with a gas by introduction of the gas during formation of the hollow glass spheres. Hollow glass microspheres having a diameter up to about 500.mu. with both thin walls (0.5 to 4.mu.) and thick walls (5 to 20.mu.) that contain various fill gases, such as Ar, Kr, Xe, Br, DT, H.sub.2, D.sub.2, He, N.sub.2, Ne, CO.sub.2, etc. in the interior thereof, can be produced by the diffusion of the fill gas or gases into the microsphere during the formation thereof from a liquid droplet of glass-forming solution. This is accomplished by filling at least a portion of the multiple-zone drop-furnace used in producing hollow microspheres with the gas or gases of interest, and then taking advantage of the high rate of gaseous diffusion of the fill gas through the wall of the gel membrane before it transforms into a glass microsphere as it is processed in the multiple-zone furnace. Almost any gas can be introduced into the inner cavity of a glass microsphere by this method during the formation of the microsphere provided that the gas is diffused into the gel membrane or microsphere prior to its transformation into glass. The process of this invention provides a significant savings of time and related expense of filling glass microspheres with various gases. For example, the time for filling a glass microballoon with 1 atmosphere of DT is reduced from about two hours to a few seconds.

  18. Carbon microsphere-filled Pyrrone foams.

    NASA Technical Reports Server (NTRS)

    Kimmel, B. G.

    1973-01-01

    Syntactic foam formulations were prepared from mixtures of Pyrrone prepolymers and hollow carbon microspheres. Very low curing shrinkages were obtained for high volume loadings of microspheres. The resulting syntactic foams were found to be remarkably stable over a wide range in temperature. A technique was developed for the emplacement of these foam formulations in polyimide-fiberglass, titanium alloy and stainless steel honeycomb without sacrificing low curing shrinkage or thermal stability.

  19. 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

  20. Comparative studies on ectopic bone formation in porous hydroxyapatite scaffolds with complementary pore structures.

    PubMed

    Wang, Hao; Zhi, Wei; Lu, Xiong; Li, Xiaohong; Duan, Ke; Duan, Rongquan; Mu, Yandong; Weng, Jie

    2013-09-01

    Vascularized bone grafts were constructed by implanting hydroxyapatite (HA) scaffolds with complementary macro-pore structures into the dorsal muscle of dogs. The relationship between pore structures and ectopic bone formation properties was investigated. Two types of scaffolds with complementary porous structures were fabricated by spherulite-accumulating and porogen-preparing methods, and were named spherulite HA-positive and porogen HA-negative, respectively. After implantation for 1 month, histological observation showed that all the scaffolds were encapsulated by normal muscle tissue and multiple vascular net with cells, indicating excellent biocompatibility and pore interconnectivity of the scaffolds. In the spherulite HA-positive scaffolds, a number of osteoclasts and osteoblasts coupled with new bone tissues were found after 3 and 6 months' implantations, which was better than those in the porogen HA-negative scaffolds. Similarly, the improvement of mechanical properties and the reconstruction of materials in the spherulite HA-positive scaffolds were superior to those in the porogen HA-negative scaffolds. The different ectopic bone formation induced by different macro-pore structures after intramuscular implantation demonstrated the significant effect of macro-pore structures of scaffolds on osteoinduction and vascularization. PMID:23732684

  1. Characterization of a hydroxyapatite sputtered film subject to hydrothermal treatment using FE-SEM and STEM.

    PubMed

    Ozeki, K; Aoki, H; Masuzawa, T

    2011-01-01

    Hydroxyapatite (HA) was coated onto a titanium substrate using radio frequency magnetron sputtering. The sputtered film was crystallized using a hydrothermal treatment. The films were observed using X-ray diffractometry, field emission scanning electron microscopy (FE-SEM) and scanning transmission electron microscopy (STEM) equipped with energy dispersive X-ray spectroscopy (EDX).It was observed that the surface of the hydrothermally-treated film was covered with globular particles. The FE-SEM observations indicated that these particles were composed of columnar grains with a grain size of 20-50 nm. In the STEM cross-sectional observation of the HA-Ti interface, HA crystalline phase regions were observed, in part, in the non-crystalline phase layer of the as-sputtered film. After the hydrothermal treatment, the HA layer crystallized; the HA crystallization proceeded to a distance of 30 nm above the titanium surface. From an EDX line scan analysis, the titanium oxide layer was not observed at the HA-Ti interface of the as-sputtered film; however, in the hydrothermally-treated film, the titanium oxide layer, with a 15 nm thickness, was observed between the mixing layer and the titanium substrate. The formation of titanium oxide at the HA-Ti interface would contribute to the adhesion improvement of the sputtered film following the hydrothermal treatment. PMID:22072082

  2. Biomimetic Collagen–Hydroxyapatite Composite Fabricated via a Novel Perfusion-Flow Mineralization Technique

    PubMed Central

    Antebi, Ben; Cheng, Xingguo; Harris, Jeffrey N.; Gower, Laurie B.; Chen, Xiao-Dong

    2013-01-01

    Prevalent three-dimensional scaffolds for bone tissue engineering are mineralized collagen–hydroxyapatite (Col/HA) composites. Conventional mineralization techniques are either to coat collagen scaffold surfaces with minerals or to simply mix collagen and mineral nanoparticles together. These conventional in vitro collagen mineralization methods are different from the in vivo bone formation process and often result in scaffolds that are not suitable for bone tissue engineering. In this study, a unique perfusion-flow (i.e., dynamic) in conjunction with a previously described polymer-induced liquid-precursor (PILP) method was used to fabricate a porous Col/HA composite. The dynamic flow emulated the physiological extracellular fluid flow containing the mineralization ions, while the PILP method facilitated the deposition of the HA crystals within the collagen fibrils (i.e., intrafibrillar mineralization). By utilizing a dynamic PILP technique to mimic the in vivo bone formation process, the resultant Col/HA composite has a similar structure and compositions like human trabecular bone. A comparison of the dynamic and static mineralization methods revealed that the novel dynamic technique facilitates more efficient and homogenous mineral deposition throughout the Col/HA composite. The dynamic intrafibrillar mineralization method generated stiff Col/HA composites with excellent surface property for cell attachment and growth. The human mesenchymal stem cells cultured on the Col/HA composites quickly remodeled the scaffolds and resulted in constructs with an extensive cell-derived extracellular matrix network. PMID:23157544

  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. Hydrothermal fabrication of hydroxyapatite/chitosan/carbon porous scaffolds for bone tissue engineering.

    PubMed

    Long, Teng; Liu, Yu-Tai; Tang, Sha; Sun, Jin-Liang; Guo, Ya-Ping; Zhu, Zhen-An

    2014-11-01

    Porous carbon fiber felts (PCFFs) have great applications in orthopedic surgery because of the strong mechanical strength, low density, high stability, and porous structure, but they are biologically inert. To improve their biological properties, we developed, for the first time, the hydroxyapatite (HA)/chitosan/carbon porous scaffolds (HCCPs). HA/chitosan nanohybrid coatings have been fabricated on PCFFs according to the following stages: (i) deposition of chitosan/calcium phosphate precursors on PCFFs; and (ii) hydrothermal transformation of the calcium phosphate precursors in chitosan matrix into HA nanocrystals. The scanning electron microscopy images indicate that PCFFs are uniformly covered with elongated HA nanoplates and chitosan, and the macropores in PCFFs still remain. Interestingly, the calcium-deficient HA crystals exist as plate-like shapes with thickness of 10-18 nm, width of 30-40 nm, and length of 80-120 nm, which are similar to the biological apatite. The HA in HCCPs is similar to the mineral of natural bone in chemical composition, crystallinity, and morphology. As compared with PCFFs, HCCPs exhibit higher in vitro bioactivity and biocompatibility because of the presence of the HA/chitosan nanohybrid coatings. HCCPs not only promote the formation of bone-like apatite in simulated body fluid, but also improve the adhesion, spreading, and proliferation of human bone marrow stromal cells. Hence, HCCPs have great potentials as scaffold materials for bone tissue engineering and implantation. PMID:24687547

  5. Comparison of Nano-Hydroxyapatite and Sodium Fluoride Mouthrinse for Remineralization of Incipient Carious Lesions

    PubMed Central

    Haghgoo, Roza; Rezvani, Mohammad Bagher; Salehi Zeinabadi, Mehdi

    2014-01-01

    Objective: Dental caries is an infectious disease that can be prevented in several ways. The aim of this study was to compare the efficacy of sodium fluoride mouthrinse and nano- hydroxyapatite (nano-HA) for the remineralization of incipient caries. Materials and Methods: After obtaining different concentrations of nano-HA (0-2-5-10%), 60 sound premolars fixed in acrylic blocks were coated with nail polish except for one surface. Ten teeth (control group) were stored in distilled water and the remaining 50 samples were demineralized by immersion in 13 ml of 0.1 M lactic acid and 0.2% poly acrylic acid for 48 hours. Their microhardness was then measured and compared to that of the control group. Next, the 50 test teeth were randomly divided into 5 groups of group1 (negative), group 2 (2% nano-HA), group 3 (5% nano-HA), group 4(10% nano-HA) and group 5 (0.2 NAF mouthrinse). The microhardness of the teeth was measured after 12 hours of immersion in the above-mentioned solutions. Data were analyzed using repeated measures analysis of variance (ANOVA). Results: Microhardness of all samples decreased significantly after immersion in the demineralization solution and increased following immersion in nano-HA and NAF mouthrinses; however, this increase was not statistically significant (P=0.711). Conclusion: Nano-HA and NAF mouthrinses can greatly enhance remineralization and increase tooth microhardness. PMID:25584051

  6. Controlled RGD Peptide Adsorption on Aggregation-Free, Size-Selected Hydroxyapatite Nanoparticle Substrates

    NASA Astrophysics Data System (ADS)

    Bapat, Parimal; Culpepper, Bonnie; Bellis, Susan; Camata, Renato

    2012-10-01

    Numerous studies of cell attachment, differentiation, and proliferation have been carried out on nanostructured hydroxyapatite (HA) surfaces with cell adhesive peptides containing the RGD (Arg-Gly-Asp) motif. Although these studies have yielded useful insights into the role of RGD peptides in cell-HA biomaterial interactions, the heterogeneity of typical nanophase HA materials makes it difficult to decouple the effects of nanotopography and biochemical cues. In this work we have used aggregation-free, size-controlled HA nanoparticles with mean size in the 20-70 nm range, synthesized by gas-phase laser ablation and deposited on atomically flat bioinert substrates that may help overcome this challenge. Nanoparticle deposits with adjustable number concentration were characterized by transmission electron microscopy, atomic force microscopy, and X-ray diffraction. RGD peptides modified by the addition of a polyglutamate sequence and a fluorescent conjugate, were coated onto the HA nanoparticle substrates. Intensity histograms of fluorescent microscopy images show that peptide adsorption on the substrates scales with the concentration of HA nanoparticles. High HA nanoparticle concentrations also lead to peptide clustering tunable in the 100-1200 cm-2.

  7. 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.

  8. 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. PMID:19012892

  9. 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.

  10. Demonstration of Microsphere Insulation in Cryogenic Vessels

    NASA Astrophysics Data System (ADS)

    Baumgartner, R. G.; Myers, E. A.; Fesmire, J. E.; Morris, D. L.; Sokalski, E. R.

    2006-04-01

    While microspheres have been recognized as a legitimate insulation material for decades, actual use in full-scale cryogenic storage tanks has not been demonstrated until now. The performance and life-cycle-cost advantages previously predicted have now been proven. Most bulk cryogenic storage tanks are insulated with either multilayer insulation (MLI) or perlite. Microsphere insulation, consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. These properties were proven during recent field testing of two 22,700-L (6,000-gallon) liquid nitrogen tanks, one insulated with microsphere insulation and the other with perlite. Normal evaporation rates (NER) for both tanks were monitored with precision test equipment and insulation levels within the tanks were observed through view ports as an indication of insulation compaction. Specific industrial applications were evaluated based on the test results and beneficial properties of microsphere insulation. Over-the-road trailers previously insulated with perlite will benefit not only from the reduced heat leak, but also the reduced mass of microsphere insulation. Economic assessments for microsphere-insulated cryogenic vessels including life-cycle cost are also presented.

  11. Interaction of Polyelectrolytes with Salivary Pellicles on Hydroxyapatite Surfaces under Erosive Acidic Conditions.

    PubMed

    Delvar, Alice; Lindh, Liselott; Arnebrant, Thomas; Sotres, Javier

    2015-09-30

    The modification of acidic beverage formulations with food-approved, nonhazardous substances with antierosive properties has been identified as a key strategy for counteracting the prevalence of dental erosion, i.e., the acid-induced dissolution of hydroxyapatite (HA, the main mineral component of tooth surfaces). While many of such substances have been reported, very little is known on how they interact with teeth and inhibit their acid-induced dissolution. With the aim of filling this gap in knowledge, we have studied under acidic conditions the interaction between two polyelectrolytes of differing ionic character, carboxymethyl cellulose (CMC) and chitosan, and saliva-coated hydroxyapatite, i.e., a model for the outer surface of teeth. These studies were performed by means of ellipsometry, quartz crystal microbalance with dissipation monitoring, and atomic force microscopy. We also studied, by means of pH variations, how dissolution of saliva-coated HA is affected by including these polyelectrolytes in the erosive solutions. Our results confirm that salivary films protect HA from acid-induced dissolution, but only for a limited time. If the acid is modified with CMC, this polyelectrolyte incorporates into the salivary films prolonging in time their protective function. Eventually, the CMC-modified salivary films are removed from the HA surfaces. From this moment, HA is continuously coated with CMC, but this offers only a weak protection against erosion. When the acid is modified with the cationic chitosan, the polyelectrolyte adsorbs on top of the salivary films. Chitosan-modified salivary films are also eventually replaced by bare chitosan films. In this case both coatings offer a similar protection against HA dissolution, which is nevertheless notably higher than that offered by CMC. PMID:26368580

  12. Curvature capillary migration of microspheres.

    PubMed

    Sharifi-Mood, Nima; Liu, Iris B; Stebe, Kathleen J

    2015-09-14

    We address the question: how does capillarity propel microspheres along curvature gradients? For a particle on a fluid interface, there are two conditions that can apply at the three phase contact line: either the contact line adopts an equilibrium contact angle, or it can be pinned by kinetic trapping, e.g. at chemical heterogeneities, asperities, or other pinning sites on the particle surface. We formulate the curvature capillary energy for both scenarios for particles smaller than the capillary length and far from any pinning boundaries. The scale and range of the distortion made by the particle are set by the particle radius; we use singular perturbation methods to find the distortions and to rigorously evaluate the associated capillary energies. For particles with equilibrium contact angles, contrary to the literature, we find that the capillary energy is negligible, with the first contribution bounded to fourth order in the product of the particle radius and the deviatoric curvature of the host interface. For pinned contact lines, we find curvature capillary energies that are finite, with a functional form investigated previously by us for disks and microcylinders on curved interfaces. In experiments, we show microspheres migrate along deterministic trajectories toward regions of maximum deviatoric curvature with curvature capillary energies ranging from 6 × 10(3)-5 × 10(4)kBT. These data agree with the curvature capillary energy for the case of pinned contact lines. The underlying physics of this migration is a coupling of the interface deviatoric curvature with the quadrupolar mode of nanometric disturbances in the interface owing to the particle's contact line undulations. This work is an example of the major implications of nanometric roughness and contact line pinning for colloidal dynamics. PMID:26154075

  13. 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 (24 days after treatment) and subacute phase (412 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

  14. 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.

  15. A chondromimetic microsphere for in situ spatially controlled chondrogenic differentiation of human mesenchymal stem cells.

    PubMed

    Ansboro, Sharon; Hayes, Jessica S; Barron, Valerie; Browne, Shane; Howard, Linda; Greiser, Udo; Lalor, Pierce; Shannon, Fintan; Barry, Frank P; Pandit, Abhay; Murphy, J Mary

    2014-04-10

    Human mesenchymal stem cells (hMSCs) have been identified as a viable cell source for cartilage tissue engineering. However, to undergo chondrogenic differentiation hMSCs require growth factors, in particular members of the transforming growth factor beta (TGF-β) family. While in vitro differentiation is feasible through continuous supplementation of TGF-β3, mechanisms to control and drive hMSCs down the chondrogenic lineage in their native microenvironment remain a significant challenge. The release of TGF-β3 from an injectable microsphere composed of the cartilage-associated extracellular matrix molecule hyaluronan represents a readily translatable approach for in situ differentiation of hMSCs for cartilage repair. In this study, chondromimetic hyaluronan microspheres were used as a growth factor delivery source for hMSC chondrogenesis. Cellular compatibility of the microspheres (1.2 and 14.1 μm) with hMSCs was shown and release of TGF-β3 from the most promising 14.1 μm microspheres to control differentiation of hMSCs was evaluated. Enhanced accumulation of cartilage-associated glycosaminoglycans by hMSCs incubated with TGF-β3-loaded microspheres was seen and positive staining for collagen type II and proteoglycan confirmed successful in vitro chondrogenesis. Gene expression analysis showed significantly increased expression of the chondrocyte-associated genes, collagen type II and aggrecan. This delivery platform resulted in significantly less collagen type X expression, suggesting the generation of a more stable cartilage phenotype. When evaluated in an ex vivo osteoarthritic cartilage model, implanted hMSCs with TGF-β3-loaded HA microspheres were detected within cartilage fibrillations and increased proteoglycan staining was seen in the tissue. In summary, data presented here demonstrate that TGF-β3-bound hyaluronan microspheres provide a suitable delivery system for induction of hMSC chondrogenesis and their use may represent a clinically feasible tissue engineering approach for the treatment of articular cartilage defects. PMID:24491910

  16. Nanocrystallized SrHA/SrHA SrTiO3/SrTiO3 TiO2 multilayer coatings formed by micro-arc oxidation for photocatalytic application

    NASA Astrophysics Data System (ADS)

    Han, Y.; Chen, D. H.; Zhang, L.

    2008-08-01

    Novel photocatalytic coatings containing strontium hydroxyapatite (SrHA), strontium titanate (SrTiO3), and TiO2 were formed by micro-arc oxidation (MAO) in an aqueous electrolyte containing strontium acetate and β-glycerophosphate disodium at 530 V for 0.1-5 min. The structure evolution of the coatings was investigated as a function of processing time, and the photocatalytic activity of the coatings was evaluated by measuring the decomposition rate of methyl orange under ultraviolet irradiation. During the MAO processing of the coatings, it was observed that some granules appeared in the electrolyte adjacent to the anode and they increased in amount as the processing time was prolonged. The obtained results show that the granules are amorphous and poorly crystallized SrHA with negative charges. The coating prepared for 5 min presents a microporous structure of SrHA/SrHA-SrTiO3/SrTiO3-TiO2 multilayers, in which the SrHA outermost layer and the SrHA-SrTiO3 intermediate layer are nanocrystallized. It is suggested that formation of the granules, electro-migration of the granules onto the pre-formed layer, and crystallization of the adhered granules are possible mechanisms for the formation of a SrHA/SrHA-SrTiO3/SrTiO3-TiO2 multilayer coating. This coating shows much higher photocatalytic decomposition efficiency relative to the MAO-formed TiO2 coating, and is expected to have an important photocatalytic application.

  17. Sol-Gel Derived Hydroxyapatite Coating on Mg-3Zn Alloy for Orthopedic Application

    NASA Astrophysics Data System (ADS)

    Singh, Sanjay; Manoj Kumar, R.; Kuntal, Kishor Kumar; Gupta, Pallavi; Das, Snehashish; Jayaganthan, R.; Roy, Partha; Lahiri, Debrupa

    2015-04-01

    In recent years, magnesium and its alloys have gained a lot of interest as orthopedic implant constituents because their biodegradability and mechanical properties are closer to that of human bone. However, one major concern with Mg in orthopedics is its high corrosion rate that results in the reduction of mechanical integrity before healing the bone tissue. The current study evaluates the sol-gel-derived hydroxyapatite (HA) coating on a selected Mg alloy (Mg-3Zn) for decreasing the corrosion rate and increasing the bioactivity of the Mg surface. The mechanical integrity of the coating is established as a function of the surface roughness of the substrate and the sintering temperature of the coating. Coating on a substrate roughness of 15-20 nm and sintering at 400°C shows the mechanical properties in similar range of bone, thus making it suitable to avoid the stress-shielding effect. The hydroxyapatite coating on the Mg alloy surface also increases corrosion resistance very significantly by 40 times. Bone cells are also found proliferating better in the HA-coated surface. All these benefits together establish the candidature of sol-gel HA-coated Mg-3Zn alloy in orthopedic application.

  18. 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.

  19. Properties of carbon nanotube-dispersed Sr-hydroxyapatite injectable material for bone defects

    PubMed Central

    Raucci, M. G.; Alvarez-Perez, M.; Giugliano, D.; Zeppetelli, S.; Ambrosio, L.

    2016-01-01

    This study concerns the synthesis of gel materials based on carbon nanotubes dispersed strontium-modified hydroxyapatite (Sr-HA) at different compositions obtained by sol–gel technology and their influence on human-bone-marrow-derived mesenchymal stem cells. Furthermore, an evaluation of the influence of nanotubes and Strontium on physico-chemical, morphological, rheological and biological properties of hydroxyapatite gel was also performed. Morphological analysis (scanning electron microscopy) shows a homogeneous distribution of modified nanotubes in the ceramic matrix improving the bioactive properties of materials. The biological investigations proved that Sr-HA/carbon nanotube gel containing 0–20 mol (%) of Sr showed no toxic effect and promote the expression of early and late markers of osteogenic differentiation in cell culture performed in basal medium without osteogenic factors. Finally, the SrHA/carbon nanotube gels could have a good potential application as filler in bone repair and regeneration and may be used in the osteoporotic disease treatment. PMID:26816652

  20. Properties of carbon nanotube-dispersed Sr-hydroxyapatite injectable material for bone defects.

    PubMed

    Raucci, M G; Alvarez-Perez, M; Giugliano, D; Zeppetelli, S; Ambrosio, L

    2016-03-01

    This study concerns the synthesis of gel materials based on carbon nanotubes dispersed strontium-modified hydroxyapatite (Sr-HA) at different compositions obtained by sol-gel technology and their influence on human-bone-marrow-derived mesenchymal stem cells. Furthermore, an evaluation of the influence of nanotubes and Strontium on physico-chemical, morphological, rheological and biological properties of hydroxyapatite gel was also performed. Morphological analysis (scanning electron microscopy) shows a homogeneous distribution of modified nanotubes in the ceramic matrix improving the bioactive properties of materials. The biological investigations proved that Sr-HA/carbon nanotube gel containing 0-20 mol (%) of Sr showed no toxic effect and promote the expression of early and late markers of osteogenic differentiation in cell culture performed in basal medium without osteogenic factors. Finally, the SrHA/carbon nanotube gels could have a good potential application as filler in bone repair and regeneration and may be used in the osteoporotic disease treatment. PMID:26816652

  1. Development of high strength hydroxyapatite for bone tissue regeneration using nanobioactive glass composites

    SciTech Connect

    Shrivastava, Pragya; Dalai, Sridhar; Vijayalakshmi, S.; Sudera, Prerna; Sivam, Santosh Param; Sharma, Pratibha

    2013-02-05

    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 SiO{sub 2} 70 mol%, CaO 26 mol % and P{sub 2}O{sub 5} 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 bone, thus proving significant for bone tissue regeneration substitutes.

  2. Enhanced MSC Chondrogenesis Following Delivery of TGF-β3 from Alginate Microspheres within Hyaluronic Acid Hydrogels In Vitro and In Vivo

    PubMed Central

    Bian, Liming; Zhai, David Y.; Tous, Elena; Rai, Reena; Mauck, Robert L.; Burdick, Jason A.

    2011-01-01

    Mesenchymal stem cells (MSCs) are being recognized as a viable cell source for cartilage repair and members of the transforming growth factor-beta (TGF-β) superfamily are a key mediator of MSC chondrogenesis. While TGF-β mediated MSC chondrogenesis is well established in in vitro pellet or hydrogel cultures, clinical translation will require effective delivery of TGF-βs in vivo. Here, we investigated the co-encapsulation of TGF-β3 containing alginate microspheres with human MSCs in hyaluronic acid (HA) hydrogels towards the development of implantable constructs for cartilage repair. TGF-β3 encapsulated in alginate microspheres with nanofilm coatings showed significantly reduced initial burst release compared to uncoated microspheres, with release times extending up to 6 days. HA hydrogel constructs seeded with MSCs and TGF-β3 containing microspheres developed comparable mechanical properties and cartilage matrix content compared to constructs supplemented with TGF-β3 continuously in culture media, whereas constructs with TGF-β3 directly encapsulated in the gels without microspheres had inferior properties. When implanted subcutaneously in nude mice, constructs containing TGF-β3 microspheres resulted in superior cartilage matrix formation to groups without TGF-β3 or with TGF-β3 added directly to the gel. However, calcification was observed in implanted constructs after 8 weeks of subcutaneous implantation. To prevent this, the co-delivery of parathyroid hormone-related protein (PTHrP) with TGF-β3 in alginate microspheres was pursued, resulting in partially reduced calcification. This study demonstrates that the controlled local delivery of TGF-β3 is essential to neocartilage formation by MSCs and that further optimization is needed to avert the differentiation of chondrogenically induced MSCs towards a hypertrophic phenotype. PMID:21652067

  3. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

    NASA Astrophysics Data System (ADS)

    Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J.; Fenniri, Hicham; Webster, Thomas J.

    2009-04-01

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml-1 HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites make them promising candidates for further study for bone tissue engineering applications.

  4. Impact formation and microstructure characterization of thermal sprayed hydroxyapatite/titania composite coatings.

    PubMed

    Li, H; Khor, K A; Cheang, P

    2003-03-01

    Formation mechanism of hydroxyapatite (HA)/titania (TiO(2)) composite coating deposited by high velocity oxy-fuel (HVOF) thermal spray process was studied, and its structural characterization was conducted and elaborated in this paper. The impact theory was employed to analyze the formation procedure of the HA/titania composite coatings. Results revealed that the crater caused by the impact of entirely unmelted TiO(2) particles on the HA matrix during coating formation was of smaller dimensions than the original size of the reinforcements. It was found that chemical reaction between the mechanically blended HA and TiO(2) powder took place exclusively during the impingement stage, and calcium titanate, CaTiO(3), was one notable by-product. The bonding between the HA matrix and TiO(2) reinforcement might have been achieved predominantly through a chemical bond that resulted from the mutual chemical reactions among the components. Differential scanning calorimetry analyses showed that the chemical reaction between HA and TiO(2) was at approximately 1410 degrees C. The TiO(2) addition was found to exert particular effects on the thermal behavior of HA at elevated temperatures, during both heating and cooling cycles. Transmission electron microscopy observation identified the chemical reaction zone between HA and TiO(2), which revealed an improved splats' interface. The reaction zone demonstrated some influence on the grain size of HA nearby during resolidification of the melted portion. A structural model was proposed to illustrate the location of the different phases in the HA/titania composite coating. PMID:12504516

  5. Hydroxyapatite-Based Biomaterials vs. Autologous Bone Graft in Spinal Fusion: An in Vivo Animal Study.

    PubMed

    Bròdano, Giovanni Barbanti; Giavaresi, Gianluca; Lolli, Francesco; Salamanna, Francesca; Parrilli, Annapaola; Martini, Lucia; Griffoni, Cristiana; Greggi, Tiziana; Arcangeli, Elena; Pressato, Daniele; Boriani, Stefano; Fini, Milena

    2014-04-01

    Study Design. An in vivo study was designed to compare the efficacy of biomimetic Magnesium-Hydroxyapatite (MgHA) and of human demineralised bone matrix (HDBM), both dispersed in a mixture of biomimetic Mg-HA nanoparticles, with that of an autologous bone graft.Objective. The objective of this study was to evaluate two new bone substitutes as alternatives to a bone autograft for spinal fusion, determining their osteoinductive and osteoconductive properties, and their capacity of remodeling, using a large animal model.Summary of Background Data. Spinal fusion is a common surgical procedure and it is performed for different conditions. A successful fusion requires potentially osteogenic, osteoinductive and osteoconductive biomaterials.Methods. A posterolateral spinal fusion model involved 18 sheep, bilaterally implanting test materials between the vertebral transverse processes. The animals were divided into two groups: one fusion level was treated with MgHA (Group 1) or with HDBM-MgHA (Group 2). The other fusion level received bone autografts in both groups.Results. Radiographic, histological and microtomographic results indicated good osteointegration between the spinous process and the vertebral foramen for both materials. Histomorphometry revealed no significant differences between MgHA and autologous bone for all the parameters examined while significantly lower values of bone volume were observed between HDBM-MgHA and autologous bone. Moreover, the normalisation of the histomorphometrical data with autologous bone revealed that MgHA showed a significantly higher value of bone volume and a lower value of trabecular number, more similar to autologous bone, in comparison to HDBM-MgHA.Conclusion. The study showed that the use of MgHA in an ovine model of spinal fusion led to the deposition of new bone tissue without qualitative and quantitative differences with respect to new bone formed with autologous bone while the HDBM-MgHA led to a reduced deposition of newly-formed bone tissue. PMID:24718060

  6. New bioactive hybrid material of nano-hydroxyapatite based on N-carboxyethylchitosan for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Lu, Yan; Zhu, Aiping; Wang, Wanpeng; Shi, Hongchan

    2010-09-01

    N-carboxyethylchitosan/nano-hydroxyapatite (NCECS/HA) composite films were fabricated and their potential applications in guiding bone regeneration were investigated in terms of their in vitro cellular activity. Fourier ransform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to investigate the structure and composition of the composite film. Field Emission scanning electron microscopy (FESEM) revealed that HA nanoparticles were dispersed homogeneously in NCECS matrix. The composite film has sufficient mechanical properties for tissue engineering scaffold. The composite film was found to have better cartilage cell adhesion and growth than pure NCECS film.

  7. Behaviour of human mesenchymal stem cells on chemically synthesized HA-PCL scaffolds for hard tissue regeneration.

    PubMed

    D'Antò, Vincenzo; Raucci, Maria Grazia; Guarino, Vincenzo; Martina, Stefano; Valletta, Rosa; Ambrosio, Luigi

    2016-02-01

    Our goal was to characterize the response of human mesenchymal stem cells (hMSCs) to a novel composite scaffold for bone tissue engineering. The hydroxyapatite-polycaprolactone (HA-PCL) composite scaffolds were prepared by a sol-gel method at room temperature and the scaffold morphology was investigated by scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) to validate the synthesis process. The response of two different lines of hMSCs, bone-marrow-derived human mesenchymal stem cells (BMSCs) and dental pulp stem cells (DPSCs) in terms of cell proliferation and differentiation into the osteoblastic phenotype, was evaluated using Alamar blue assay, SEM, histology and alkaline phosphatase activity. Our results indicate that tissue engineering by means of composite HA-PCL scaffolds may represent a new therapeutic strategy to repair craniofacial bone defects. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23723157

  8. Osseointegrative Properties of Electrospun Hydroxyapatite-Containing Nanofibrous Chitosan Scaffolds

    PubMed Central

    Frohbergh, Michael E.; Katsman, Anya; Mondrinos, Mark J.; Stabler, Collin T.; Hankenson, Kurt D.; Oristaglio, Jeffrey T.

    2015-01-01

    Our long-term goal is to develop smart biomaterials that can facilitate regeneration of critical-size craniofacial lesions. In this study, we tested the hypothesis that biomimetic scaffolds electrospun from chitosan (CTS) will promote tissue repair and regeneration in a critical size calvarial defect. To test this hypothesis, we first compared in vitro ability of electrospun CTS scaffolds crosslinked with genipin (CTS-GP) to those of mineralized CTS-GP scaffolds containing hydroxyapatite (CTS-HA-GP), by assessing proliferation/metabolic activity and alkaline phosphatase (ALP) levels of murine mesenchymal stem cells (mMSCs). The cells' metabolic activity exhibited a biphasic behavior, indicative of initial proliferation followed by subsequent differentiation for all scaffolds. ALP activity of mMSCs, a surrogate measure of osteogenic differentiation, increased over time in culture. After 3 weeks in maintenance medium, ALP activity of mMSCs seeded onto CTS-HA-GP scaffolds was approximately two times higher than that of cells cultured on CTS-GP scaffolds. The mineralized CTS-HA-GP scaffolds were also osseointegrative in vivo, as inferred from the enhanced bone regeneration in a murine model of critical size calvarial defects. Tissue regeneration was evaluated over a 3 month period by microCT and histology (Hematoxylin and Eosin and Masson's Trichrome). Treatment of the lesions with CTS-HA-GP scaffolds induced a 38% increase in the area of de novo generated mineralized tissue area after 3 months, whereas CTS-GP scaffolds only led to a 10% increase. Preseeding with mMSCs significantly enhanced the regenerative capacity of CTS-GP scaffolds (by ∼3-fold), to 35% increase in mineralized tissue area after 3 months. CTS-HA-GP scaffolds preseeded with mMSCs yielded 45% new mineralized tissue formation in the defects. We conclude that the presence of HA in the CTS-GP scaffolds significantly enhances their osseointegrative capacity and that mineralized chitosan-based scaffolds crosslinked with genipin may represent a unique biomaterial with possible clinical relevance for the repair of critical calvarial bone defects. PMID:25336062

  9. Microstructure and mechanical properties of an Mg-3Zn- o.5Zr-5HA nanocomposite processed by ECAE

    NASA Astrophysics Data System (ADS)

    Li, J.; Huang, Y.

    2014-08-01

    Mg matrix composites reinforced by natural bone constituent hydroxyapatite (HA) particles have shown promising in-vitro corrosion resistance but are inconsistent in both electrochemical and mechanical performances because of severe particle segregations. The present work was carried out to investigate the feasibility of a novel technology that combines high shear solidification and equal channel angular extrusion (ECAE) for fabricating Mg-HA nanocomposites. Experiments showed that the high shear solidification resulted in a fine and uniform grain structure with a globally uniform HA nanoparticles in fine clusters and the ECAE processing of the as-cast composites resulted in further grain refinement and more importantly the breakdown of nanoparticle aggregates, leading to the formation of a dispersion of true nanoparticles in the Mg alloy matrix with improved mechanical properties. This paper describes mainly the microstructural features and mechanical performance of Mg-3Zn-0.5Zr-xHA (x = 1, 3, 5, 10) nanocomposites, in which the HA was in spherical shape with an average diameter of ~20nm

  10. Hierarchical Structure and Mechanical Improvement of an n-HA/GCO-PU Composite Scaffold for Bone Regeneration.

    PubMed

    Li, Limei; Zuo, Yi; Zou, Qin; Yang, Boyuan; Lin, Lili; Li, Jidong; Li, Yubao

    2015-10-14

    To improve the mechanical properties of bone tissue and achieve the desired bone tissue regeneration for orthopedic surgery, newly designed hydroxyapatite/polyurethane (HA/PU) porous scaffolds were developed via in situ polymerization. The results showed that the molecular modification of PU soft segments by glyceride of castor oil (GCO) can increase the scaffold compressive strength by 48% and the elastic modulus by 96%. When nano-HA (n-HA) particles were incorporated into the GCO-PU matrix, the compressive strength and elastic modulus further increased by 49 and 74%, from 2.91 to 4.34 MPa and from 95 to 165.36 MPa, respectively. The n-HA particles with fine dispersity not only improved the interface bonding with the GCO-PU matrix but also provided effective bioactivity for bonding with bone tissue. The hierarchical structure and mechanical quality of the n-HA/GCO-PU composite scaffold were determined to be appropriate for the growth of cells and the regeneration of bony tissues, demonstrating promising prospects for bone repair and regeneration. PMID:26406396

  11. An in vivo evaluation of PLLA/PLLA-gHA nano-composite for internal fixation of mandibular bone fractures.

    PubMed

    Peng, Weihai; Zheng, Wei; Shi, Kai; Wang, Wangshu; Shao, Ying; Zhang, Duo

    2015-12-01

    Internal fixation of bone fractures using biodegradable poly(L-lactic-acid) (PLLA)-based materials has attracted the attention of many researchers. In the present study, 36 male beagle dogs were randomly assigned to two groups: PLLA/PLLA-gHA (PLLA-grafted hydroxyapatite) group and PLLA group. PLLA/PLLA-gHA and PLLA plates were embedded in the muscular bags of the erector spinae and also implanted to fix mandibular bone fractures in respective groups. At 1, 2, 3, 6, 9, and 12 months postoperatively, the PLLA/PLLA-gHA and PLLA plates were evaluated by adsorption and degradation tests, and the mandibles were examined through radiographic analysis, biomechanical testing, and histological analysis. The PLLA/PLLA-gHA plates were non-transparent and showed a creamy white color, and the PLLA plates were transparent and faint yellow in color. At all time points following surgery, adsorption and degradation of the PLLA/PLLA-gHA plates were significantly less than those of the PLLA plates, and the lateral and longitudinal bending strengths of the surgically treated mandibles of the beagle dogs in the PLLA/PLLA-gHA group were significantly greater than those of the PLLA group and reached almost the value of intact mandibles at 12 months postoperatively. Additionally, relatively rapid bone healing was observed in the PLLA/PLLA-gHA group with the formation of new lamellar bone tissues at 12 months after the surgery. The PLLA/PLLA-gHA nano-composite can be employed as a biodegradable material for internal fixation of mandibular bone fractures. PMID:26551378

  12. Finite Element Simulation of Diametral Strength Test of Hydroxyapatite

    SciTech Connect

    Ozturk, Fahrettin; Toros, Serkan; Evis, Zafer

    2011-01-17

    In this study, the diametral strength test of sintered hydroxyapatite was simulated by the finite element software, ABAQUS/Standard. Stress distributions on diametral test sample were determined. The effect of sintering temperature on stress distribution of hydroxyapatite was studied. It was concluded that high sintering temperatures did not reduce the stress on hydroxyapatite. It had a negative effect on stress distribution of hydroxyapatite after 1300 deg. C. In addition to the porosity, other factors (sintering temperature, presence of phases and the degree of crystallinity) affect the diametral strength of the hydroxyapatite.

  13. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods.

    PubMed

    González Ocampo, Jazmín I; Escobar Sierra, Diana M; Ossa Orozco, Claudia P

    2016-03-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering. PMID:26966570

  14. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods

    PubMed Central

    González Ocampo, Jazmín I.; Escobar Sierra, Diana M.; Ossa Orozco, Claudia P.

    2015-01-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering. PMID:26966570

  15. How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?

    PubMed

    Wang, Kean; Liao, Kin; Goh, Kheng Lim

    2015-01-01

    Hydroxyapatite (HA) nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20-0.30 (HA mass fraction), beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters-further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is sensitive to HA concentration and crystallization temperature, and there exists a critical concentration level whereby the magnitude of the mechanical property is a minimum. PMID:26473936

  16. How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?

    PubMed Central

    Wang, Kean; Liao, Kin; Goh, Kheng Lim

    2015-01-01

    Hydroxyapatite (HA) nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20–0.30 (HA mass fraction), beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters—further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is sensitive to HA concentration and crystallization temperature, and there exists a critical concentration level whereby the magnitude of the mechanical property is a minimum. PMID:26473936

  17. Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

    PubMed Central

    Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

    2011-01-01

    Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices. PMID:20880853

  18. Fabrication of DNA/Hydroxyapatite nanocomposites by simulated body fluid for gene delivery

    SciTech Connect

    Takeshita, Takayuki; Okamoto, Masami

    2015-05-22

    The hydroxyapatite (HA) formation on the surface of DNA molecules in simulated body fluid (SBF) was examined. The osteoconductivity is estimated using SBF having ion concentrations approximately equal to those of human blood plasma. After immersion for 4 weeks in SBF at 36.5 °C, the HA crystallites possessing 1-14 micrometer in diameter grew on the surface of DNA molecules. The leaf flake-like and spherical shapes morphologies were observed through scanning electron microscopy analysis. Original peaks of both of DNA and HA were characterized by fourier transform infrared spectroscopy. The Ca/P ratio (1.1-1.5) in HA was estimated by energy dispersive X-ray analysis. After biomineralization, the calculated weight ratio of DNA/HA was 18/82 by thermogravimetry/differential thermal analysis. The molecular orbital computer simulation has been used to probe the interaction of DNA with two charge-balancing ions, CaOH{sup +} and CaH{sub 2}PO{sub 4}{sup +}. The adsorption enthalpy of the two ions on DNA having negative value was the evidence for the interface in mineralization of HA in SBF.

  19. Coupling Hydroxyapatite Nanocrystals with Lactoferrin as a Promising Strategy to Fine Regulate Bone Homeostasis.

    PubMed

    Montesi, Monica; Panseri, Silvia; Iafisco, Michele; Adamiano, Alessio; Tampieri, Anna

    2015-01-01

    Lactoferrin (LF) is an interesting glycoprotein in the field of bone biology for its regulatory effect on cells involved in bone remodeling, that results compromised in several pathological conditions, as osteoporosis. In a previous study we observed that the coupling of LF and biomimetic hydroxyapatite nanocrystals (HA), a material well-known for its bioactivity and osteoconductive properties, leads to a combined effect in the induction of osteogenic differentiation of mesenchymal stem cells. On the basis of this evidence, the present study is an extension of our previous work aiming to investigate the synergistic effect of the coupling of HA and LF on bone homeostasis. Biomimetic HA nanocrystals were synthesized and functionalized with LF (HA-LF) and then pre-osteoblasts (MC3T3-E1) and monocyte/macrophage cells lines (RAW 264.7), using as osteoclastogenesis in vitro model, were cultured separately or in co-culture in presence of HA-LF. The results clearly revealed that HA and LF act in synergism in the regulation of the bone homeostasis, working as anabolic factor for osteoblasts differentiation and bone matrix deposition, and as inhibitor of the osteoclast formation and activity. PMID:26148296

  20. Coupling Hydroxyapatite Nanocrystals with Lactoferrin as a Promising Strategy to Fine Regulate Bone Homeostasis

    PubMed Central

    Montesi, Monica; Panseri, Silvia; Iafisco, Michele; Adamiano, Alessio; Tampieri, Anna

    2015-01-01

    Lactoferrin (LF) is an interesting glycoprotein in the field of bone biology for its regulatory effect on cells involved in bone remodeling, that results compromised in several pathological conditions, as osteoporosis. In a previous study we observed that the coupling of LF and biomimetic hydroxyapatite nanocrystals (HA), a material well-known for its bioactivity and osteoconductive properties, leads to a combined effect in the induction of osteogenic differentiation of mesenchymal stem cells. On the basis of this evidence, the present study is an extension of our previous work aiming to investigate the synergistic effect of the coupling of HA and LF on bone homeostasis. Biomimetic HA nanocrystals were synthesized and functionalized with LF (HA-LF) and then pre-osteoblasts (MC3T3-E1) and monocyte/macrophage cells lines (RAW 264.7), using as osteoclastogenesis in vitro model, were cultured separately or in co-culture in presence of HA-LF. The results clearly revealed that HA and LF act in synergism in the regulation of the bone homeostasis, working as anabolic factor for osteoblasts differentiation and bone matrix deposition, and as inhibitor of the osteoclast formation and activity. PMID:26148296

  1. Synthesis of magnesium- and manganese-doped hydroxyapatite structures assisted by the simultaneous incorporation of strontium.

    PubMed

    Moreira, Mirna Pereira; de Almeida Soares, Gloria Dulce; Dentzer, Joseph; Anselme, Karine; de Sena, Lídia Ágata; Kuznetsov, Alexei; Santos, Euler Araujo Dos

    2016-04-01

    Samples of crystalline hydroxyapatite (HA) with and without the addition of individual Mg(2+), Mn(2+) and Sr(2+) ions and samples with the addition of all three ions simultaneously were prepared using the precipitation method in an aqueous medium. Chemical, structural, spectroscopic and thermophysical analyses of the synthesized samples were conducted. The obtained results indicate that Sr(2+) ions were easily incorporated into the HA crystal structure, whereas it was difficult to incorporate Mg(2+) and Mn(2+) ions into the HA lattice when these ions were individually introduced into the samples. The synthesis of HA with Mg(2+) or Mn(2+) ions is characterized by the formation of HA with a low concentration of doping elements that is outweighed by the amount of these atoms present in less biocompatible phases that formed simultaneously. However, the incorporation of Sr(2+) along with Mg(2+) and Mn(2+) ions into the samples allowed for the synthesis of HA with considerably higher concentrations of Mg(2+) and Mn(2+) in the crystal lattice. PMID:26838904

  2. Fabrication of DNA/Hydroxyapatite nanocomposites by simulated body fluid for gene delivery

    NASA Astrophysics Data System (ADS)

    Takeshita, Takayuki; Okamoto, Masami

    2015-05-01

    The hydroxyapatite (HA) formation on the surface of DNA molecules in simulated body fluid (SBF) was examined. The osteoconductivity is estimated using SBF having ion concentrations approximately equal to those of human blood plasma. After immersion for 4 weeks in SBF at 36.5 °C, the HA crystallites possessing 1-14 micrometer in diameter grew on the surface of DNA molecules. The leaf flake-like and spherical shapes morphologies were observed through scanning electron microscopy analysis. Original peaks of both of DNA and HA were characterized by fourier transform infrared spectroscopy. The Ca/P ratio (1.1-1.5) in HA was estimated by energy dispersive X-ray analysis. After biomineralization, the calculated weight ratio of DNA/HA was 18/82 by thermogravimetry/differential thermal analysis. The molecular orbital computer simulation has been used to probe the interaction of DNA with two charge-balancing ions, CaOH+ and C a H2P O4+ . The adsorption enthalpy of the two ions on DNA having negative value was the evidence for the interface in mineralization of HA in SBF.

  3. Decoupling the role of stiffness from other hydroxyapatite signalling cues in periosteal derived stem cell differentiation

    PubMed Central

    Mattei, Giorgio; Ferretti, Concetta; Tirella, Annalisa; Ahluwalia, Arti; Mattioli-Belmonte, Monica

    2015-01-01

    Bone extracellular matrix (ECM) is a natural composite made of collagen and mineral hydroxyapatite (HA). Dynamic cell-ECM interactions play a critical role in regulating cell differentiation and function. Understanding the principal ECM cues promoting osteogenic differentiation would be pivotal for both bone tissue engineering and regenerative medicine. Altering the mineral content generally modifies the stiffness as well as other physicochemical cues provided by composite materials, complicating the “cause-effect” analysis of resultant cell behaviour. To isolate the contribution of mechanical cues from other HA-derived signals, we developed and characterised composite HA/gelatin scaffolds with different mineral contents along with a set of stiffness-matched HA-free gelatin scaffolds. Samples were seeded with human periosteal derived progenitor cells (PDPCs) and cultured over 7 days, analysing their resultant morphology and gene expression. Our results show that both stiffness and HA contribute to directing PDPC osteogenic differentiation, highlighting the role of stiffness in triggering the expression of osteogenic genes and of HA in accelerating the process, particularly at high concentrations. PMID:26035412

  4. In Vitro Evaluation of Bioactivity of Chemically Deposited Hydroxyapatite on Polyether Ether Ketone

    PubMed Central

    Almasi, D.; Izman, S.; Sadeghi, M.; Iqbal, N.; Roozbahani, F.; Krishnamurithy, G.; Kamarul, T.; Abdul Kadir, M. R.

    2015-01-01

    Polyether ether ketone (PEEK) is considered the best alternative material for titanium for spinal fusion cage implants due to its low elasticity modulus and radiolucent property. The main problem of PEEK is its bioinert properties. Coating with hydroxyapatite (HA) showed very good improvement in bioactivity of the PEEK implants. However the existing methods for deposition of HA have some disadvantages and damage the PEEK substrate. In our previous study a new method for deposition of HA on PEEK was presented. In this study cell proliferation of mesenchymal stem cell and apatite formation in simulated body fluid (SBF) tests were conducted to probe the effect of this new method in improvement of the bioactivity of PEEK. The mesenchymal stem cell proliferation result showed better cells proliferation on the treated layer in comparison with untreated PEEK. The apatite formation results showed the growth of the HA on the treated PEEK but there was not any sight of the growth of HA on the untreated PEEK even after 2 weeks. The results showed the new method of the HA deposition improved the bioactivity of the treated PEEK in comparison with the bare PEEK. PMID:25838826

  5. Hydroxyapatite formation on graphene oxide modified with amino acids: arginine versus glutamic acid.

    PubMed

    Tavafoghi, M; Brodusch, N; Gauvin, R; Cerruti, M

    2016-01-01

    Hydroxyapatite (HA, Ca5(PO4)3OH) is the main inorganic component of hard tissues, such as bone and dentine. HA nucleation involves a set of negatively charged phosphorylated proteins known as non-collagenous proteins (NCPs). These proteins attract Ca(2+) and PO4(3-) ions and increase the local supersaturation to a level required for HA precipitation. Polar and charged amino acids (AAs) are highly expressed in NCPs, and seem to be responsible for the mineralizing effect of NCPs; however, the individual effect of these AAs on HA mineralization is still unclear. In this work, we investigate the effect of a negatively charged (Glu) and positively charged (Arg) AA bound to carboxylated graphene oxide (CGO) on HA mineralization in simulated body fluids (SBF). Our results show that Arg induces HA precipitation faster and in larger amounts than Glu. We attribute this to the higher stability of the complexes formed between Arg and Ca(2+) and PO4(3-) ions, and also to the fact that Arg exposes both carboxyl and amino groups on the surface. These can electrostatically attract both Ca(2+) and PO4(3-) ions, thus increasing local supersaturation more than Glu, which exposes carboxyl groups only. PMID:26791001

  6. Mechanisms of enhanced osteoblast gene expression in the presence of hydroxyapatite coated iron oxide magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tran, Nhiem; Hall, Douglas; Webster, Thomas J.

    2012-11-01

    Hydroxyapatite (HA) coated iron oxide (Fe3O4) magnetic nanoparticles have b