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Sample records for calcium hydroxyapatite optimisation

  1. A novel microwave synthesis of calcium hydroxyapatite. Optimisation and investigation of a microwave assisted reaction route

    CERN Document Server

    Zawahreh, Y

    2001-01-01

    Hydroxyapatite is a bioactive calcium phosphate used in non-load bearing applications, such as space-filling in maxillofacial reconstruction. As a coating, hydroxyapatite is used on load-bearing orthopaedic metal prostheses to improve fixation and/or biocompatibility. Conventional synthesis processes for the production of hydroxyapatite are time-consuming and labour-intensive. Microwave irradiation was investigated as a means to enhance the synthesis reaction using calcium hydroxide (Ca(OH) sub 2) and orthophosphoric acid (H sub 3 PO sub 4) as reactants. An initial set of reactions indicated the feasibility of the microwave synthesis route. Optimisation reactions were then performed followed by investigation sets of reactions. Parameters such as microwave power, irradiation time, and reactant concentrations were varied. Using 0.5M Ca(OH) sub 2 and 0.3M H sub 3 PO sub 4 , a phase-pure hydroxyapatite powder with a stoichiometric molar Ca/P ratio of 1.67 was produced in 60 seconds at 450W and 2.45GHz. The microw...

  2. Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method. Optimisation, characterisation and rheology.

    Science.gov (United States)

    Tredwin, Christopher J; Young, Anne M; Georgiou, George; Shin, Song-Hee; Kim, Hae-Won; Knowles, Jonathan C

    2013-02-01

    Currently, most titanium implant coatings are made using hydroxyapatite and a plasma spraying technique. There are however limitations associated with plasma spraying processes including poor adherence, high porosity and cost. An alternative method utilising the sol-gel technique offers many potential advantages but is currently lacking research data for this application. It was the objective of this study to characterise and optimise the production of Hydroxyapatite (HA), fluorhydroxyapatite (FHA) and fluorapatite (FA) using a sol-gel technique and assess the rheological properties of these materials. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethylphosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the sol-gel derived FHA and FA. Optimisation of the chemistry and subsequent characterisation of the sol-gel derived materials was carried out using X-ray Diffraction (XRD) and Differential Thermal Analysis (DTA). Rheology of the sol-gels was investigated using a viscometer and contact angle measurement. A protocol was established that allowed synthesis of HA, FHA and FA that were at least 99% phase pure. The more fluoride incorporated into the apatite structure; the lower the crystallisation temperature, the smaller the unit cell size (changes in the a-axis), the higher the viscosity and contact angle of the sol-gel derived apatite. A technique has been developed for the production of HA, FHA and FA by the sol-gel technique. Increasing fluoride substitution in the apatite structure alters the potential coating properties. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  3. Ostrich eggshell as calcium source for the synthesis of hydroxyapatite and hydroxyapatite partially substituted with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, J.R.M.; Louro, L.H.L.; Costa, A.M.; Silva, M.H. Prado da [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil); Campos, J.B. de, E-mail: josericardo@r-crio.com, E-mail: louro@ime.eb.br, E-mail: andrea@r-crio.com, E-mail: brantjose@gmail.com, E-mail: marceloprado@ime.eb.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil)

    2016-10-15

    In the present study, hydroxyapatite and Zn-substituted hydroxyapatite powders were synthesized using ostrich eggshell as a calcium source. The samples were analyzed by scanning electron microscopy with field emission gun, and X-ray diffraction (XRD) to identify the present phases, and X-ray fluorescence spectroscopy for quantitative chemical analysis of the synthesized and heat treated powders. The Fourier transform infrared spectroscopy technique was used before and after heat treatments at 700, 900 and 1100 °C in order to identify the functional groups present, as an additional technique to the XRD analysis. The results presented in this study represent a promising method for synthesis of hydroxyapatite and hydroxyapatite partially substituted with zinc, since the results showed no undesirable phases or impurities in the produced powders. It was observed that Zn-substituted hydroxyapatite showed higher thermal stability, when compared to pure hydroxyapatite. (author)

  4. Ostrich eggshell as calcium source for the synthesis of hydroxyapatite and hydroxyapatite partially substituted with zinc

    OpenAIRE

    Ferreira,J. R. M.; Louro,L. H. L.; Costa, A. M.; Campos, J. B; Silva,M. H. Prado da

    2016-01-01

    Abstract In the present study, hydroxyapatite and Zn-substituted hydroxyapatite powders were synthesized using ostrich eggshell as a calcium source. The samples were analyzed by scanning electron microscopy with field emission gun, and X-ray diffraction (XRD) to identify the present phases, and X-ray fluorescence spectroscopy for quantitative chemical analysis of the synthesized and heat treated powders. The Fourier transform infrared spectroscopy technique was used before and after heat trea...

  5. Effect of fuel characteristics on synthesis of calcium hydroxyapatite ...

    Indian Academy of Sciences (India)

    The effect of fuel characteristics on the processing of nano sized calcium hydroxyapatite (HA) fine powders by the solution combustion technique is reported. Urea, glycine and glucose were used as fuels in this study. By using different combinations of urea and glycine fuels and occasional addition of small amounts of ...

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

    Science.gov (United States)

    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.

  7. Osteoblast response to nanocrystalline calcium hydroxyapatite depends on carbonate content.

    Science.gov (United States)

    Adams, Brandy R; Mostafa, Amany; Schwartz, Zvi; Boyan, Barbara D

    2014-09-01

    Normal bone mineral is a carbonated-apatite, but there are limited data on the effect of mineral containing carbonate on cell response. We characterized surface chemical compositions of three experimental carbonated hydroxyapatite (CO3(2-) HA) substrates and investigated their effect on osteoblast differentiation. Carbonate was incorporated into the hydroxyapatite powders while phosphate and hydroxyl groups were shown to be reduced by analyzing the chemical composition of the substrate surfaces. CO3(2-) HA powders with increasing carbonate concentrations designated as C1 (3.88%), C2 (4.85%), and C3 (5.82%) were molded, pressed, and fired into 14 mm discs. We observed that calcium phosphate ratios increased monotonically with increasing carbonate content, whereas differentiation of MG63 cells decreased. CO3(2-) HA surfaces also affected factor production. Addition of carbonate caused a 70% reduction in osteoprotegerin (OPG) compared to cultures on pure HA, but the effect of carbonate was not dose-dependent. Low carbonate content reduced VEGF-A by 80%, but higher levels of carbonate reversed this effect in a concentration dependent manner, with the C3 VEFG-A levels approximately twice that of C1 levels. These observations collectively indicate that bone cells are sensitive to carbonate content in bone mineral and the effects of carbonate substitution vary with the outcome being measured. Overall, this study provides a preliminary understanding of how carbonate substitution within hydroxyapatite modulates cellular behavior. © 2013 Wiley Periodicals, Inc.

  8. Variation of crystal structure of hydroxyapatite in calcium phosphate cement by the substitution of strontium ions.

    Science.gov (United States)

    Wang, Xiupeng; Ye, Jiandong

    2008-03-01

    New routes were used to introduce strontium into calcium phosphate cement in the present article. The study showed that by mixing 50 wt% amorphous calcium phosphate + amorphous strontium phosphate and 50 wt% dicalcium phosphate dihydrate, hydroxyapatite and Sr-hydroxyapatite precipitated separately in the hydrated cement; whereas, by mixing 50 wt% Sr- amorphous calcium phosphate and 50 wt% dicalcium phosphate dihydrate, strontium can be doped into hydroxyapatite lattice and increase the lattice dimensions and lattice volume. The strontium substituted calcium phosphate cement has potential for use in orthopedic surgeries.

  9. Evolution of the calcium hydroxyapatite crystal structure under plasma deposition and subsequent reducing treatment

    Science.gov (United States)

    Shamrai, V. F.; Karpikhin, A. E.; Sirotinkin, V. P.; Kalita, V. I.; Komlev, D. I.

    2014-03-01

    The structure of hydroxyapatite plasma coatings on a titanium substrate has been investigated by the X-ray Rietveld method. The hydroxyapatite crystal structure in plasma-deposited samples is characterized by strong distortions of its main element (tetrahedral PO4 cluster) and coordination calcium polyhedra, as well as calcium deficit in the Ca2 site; however, these features do not change the main motif of the hydroxyapatite structure. The bond distortions in PO4 clusters are estimated by the Bauer method. It is shown that hydrothermal treatment leads to the almost complete recovery of the hydroxyapatite structure.

  10. Synthesis and characterization of cadmium-calcium hydroxyapatite solid solutions

    Science.gov (United States)

    Zhao, Xin; Zhu, Yi-nian; Dai, Liu-qin

    2014-06-01

    A series of cadmium-calcium hydroxyapatite solid solutions was prepared by an aqueous precipitation method. By various means, the characterizations confirmed the formation of continuous solid solutions over all ranges of Cd/(Cd+Ca) atomic ratio. In the results, both lattice parameters a and c display slight deviations from Vegard's rule when the Cd/(Cd+Ca) atomic ratio is greater than 0.6. The particles change from smaller acicular to larger hexagonal columnar crystals as the Cd/(Cd+Ca) atomic ratio increases from 0-0.60 to 0.60-1.00. The area of the phosphate peak for symmetric P-O stretching decreases with the increase in Cd/(Cd+Ca) atomic ratio, and the peak disappears when the Cd/(Cd+Ca) atomic ratio is greater than 0.6; the two phosphate peaks of P-O stretching gradually merge together for the Cd/(Cd+Ca) atomic ratio near 0.60. These variations can be explained by a slight tendency of larger Cd ions to occupy M(2) sites and smaller Ca ions to prefer M(1) sites in the structure.

  11. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate.

    Science.gov (United States)

    Warren, L M; Mackenzie, A; Dance, D R; Young, K C

    2013-04-07

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  12. A microstructural study of the degradation and calcium release from hydroxyapatite-calcium oxide ceramics made by infiltration.

    Science.gov (United States)

    Zhang, Qinghao; Schmelzer, Eva; Gerlach, Jörg C; Nettleship, Ian

    2017-04-01

    Hydroxyapatite pellets, partially densified in a low-temperature heat treatment, were infiltrated with calcium nitrate solution followed by in-situ precipitation of Ca(OH)2 and CaCO3. The infiltrated bodies were then densified to high relative density and the calcium carbonate transformed to calcium oxide during sintering and resulted in biphasic hydroxyapatite-CaO ceramics. This work investigated the influence of the infiltration on surface morphology, weight change, and microstructural-level degradation caused by exposure to saline at pH=7.4 and a temperature of 20°C. The CaO rendered the materials more susceptible to degradation, and released calcium into the saline faster than single phase, calcium deficient hydroxyapatite (HA) that were used as a control. In consequence, these ceramics could be used to release calcium into the culture microenvironments of bone tissue or bone marrow cells next to a scaffold surface. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Peptides of Matrix Gla protein inhibit nucleation and growth of hydroxyapatite and calcium oxalate monohydrate crystals.

    Directory of Open Access Journals (Sweden)

    Maria Goiko

    Full Text Available Matrix Gla protein (MGP is a phosphorylated and γ-carboxylated protein that has been shown to prevent the deposition of hydroxyapatite crystals in the walls of blood vessels. MGP is also expressed in kidney and may inhibit the formation of kidney stones, which mainly consist of another crystalline phase, calcium oxalate monohydrate. To determine the mechanism by which MGP prevents soft-tissue calcification, we have synthesized peptides corresponding to the phosphorylated and γ-carboxylated sequences of human MGP in both post-translationally modified and non-modified forms. The effects of these peptides on hydroxyapatite formation and calcium oxalate crystallization were quantified using dynamic light scattering and scanning electron microscopy, respectively. Peptides YGlapS (MGP1-14: YγEpSHEpSMEpSYELNP, YEpS (YEpSHEpSMEpSYELNP, YGlaS (YγESHESMESYELNP and SK-Gla (MGP43-56: SKPVHγELNRγEACDD inhibited formation of hydroxyapatite in order of potency YGlapS > YEpS > YGlaS > SK-Gla. The effects of YGlapS, YEpS and YGlaS on hydroxyapatite formation were on both crystal nucleation and growth; the effect of SK-Gla was on nucleation. YGlapS and YEpS significantly inhibited the growth of calcium oxalate monohydrate crystals, while simultaneously promoting the formation of calcium oxalate dihydrate. The effects of these phosphopeptides on calcium oxalate monohydrate formation were on growth of crystals rather than nucleation. We have shown that the use of dynamic light scattering allows inhibitors of hydroxyapatite nucleation and growth to be distinguished. We have also demonstrated for the first time that MGP peptides inhibit the formation of calcium oxalate monohydrate. Based on the latter finding, we propose that MGP function not only to prevent blood-vessel calcification but also to inhibit stone formation in kidney.

  14. FORMATION OF PHOSPHATE-CONTAINING CALCIUM-FLUORIDE AT THE EXPENSE OF ENAMEL, HYDROXYAPATITE AND FLUORAPATITE

    NARCIS (Netherlands)

    CHRISTOFFERSEN, J; CHRISTOFFERSEN, MR; ARENDS, J; LEONARDSEN, ES

    1995-01-01

    During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were

  15. Microwave-assisted biomimetic synthesis of hydroxyapatite using different sources of calcium.

    Science.gov (United States)

    Türk, S; Altınsoy, I; ÇelebiEfe, G; Ipek, M; Özacar, M; Bindal, C

    2017-07-01

    In this study, some properties of biomimetic synthesized hydroxyapatite by using different sources of calcium were investigated. Biomimetic synthesis of hydroxyapatite was carried out in microwave oven using 1.5 simulated body fluid (SBF) solution having different calcium sources with 800W power for 15min. As phosphorus source di-ammonium hydrogen phosphate ((NH4)2HPO4) while for each sample as a calcium sources calcium chloride (CaCl2), calcium nitrate tetra hydrate (Ca(NO3)2·4H2O) and calcium hydroxide (Ca(OH)2) were utilized, respectively. For comparison, precipitation process was also performed in only 1.5 SBF solution without calcium and phosphorus sources. The presence of phases in synthesized hydroxyapatite was confirmed by XRD. The crystallinity and crystalline size of the phases in as synthesized powders were also calculated by using XRD data. It was found that the unique phase is hydroxyapatite (HAp, Ca5(PO4)3(OH)) by using the calcium nitrate tetra hydrate and calcium hydroxide sources, while the dominant phases are tri-calcium phosphates (TCP) and HAp for CaCl2 source and 1.5SBF which does not contain any additional Ca source. SEM studies revealed that nano-hexagonal rods and nano-spherical hydroxyapatites could be synthesized by using this process. Energy-dispersive X-ray spectroscopy (EDS) analysis revealed that the Ca/P ratio near to be as 1.5 which is the value for HAp in bone. Raman and Fourier transform-infrared spectroscopy (FT-IR) results combined with the X-ray diffraction (XRD) indicates that dominantly the present of single phase is HAp. The crystal size and fraction crystallinity of as synthesized HAp powders were changed between 29.5 and 45.4nm and 0.53-2.37, respectively. Results showed that microwave assisted biomimetic synthesis is a promising method for obtaining HAp powders in shorter process time. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Self-hardening calcium deficient hydroxyapatite/gelatine foams for bone regeneration.

    Science.gov (United States)

    Montufar, Edgar B; Traykova, Tania; Schacht, Etienne; Ambrosio, Luigi; Santin, Matteo; Planell, Josep A; Ginebra, Maria-Pau

    2010-03-01

    In this work gelatine was used as multifunctional additive to obtain injectable self-setting hydroxyapatite/gelatine composite foams for bone regeneration. The foaming and colloidal stabilization properties of gelatine are well known in food and pharmaceutical applications. Solid foams were obtained by foaming liquid gelatine solutions at 50 degrees C, followed by mixing them with a cement powder consisting of alpha tricalcium phosphate. Gelatine addition improved the cohesion and injectability of the cement paste. After setting the foamed paste transformed into a calcium deficient hydroxyapatite. The final porosity, pore interconnectivity and pore size were modulated by modifying the gelatine content in the liquid phase.

  17. Electrospinning of calcium carbonate fibers and their conversion to nanocrystalline hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Holopainen, Jani, E-mail: jani.holopainen@helsinki.fi; Santala, Eero; Heikkilä, Mikko; Ritala, Mikko

    2014-12-01

    Calcium carbonate (CaCO{sub 3}) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO{sub 3}){sub 2}·4H{sub 2}O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO{sub 3} fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO{sub 3} layer by spin or dip coating Ca(NO{sub 3}){sub 2}/PVP precursor solution on the CaCO{sub 3} fibers followed by annealing of the gel formed inside the fiber layer. The CaCO{sub 3} fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings. - Highlights: • Calcium carbonate fibers were prepared by electrospinning. • The electrospun fibers crystallized to calcite upon calcination at 500 °C. • Spin and dip coating methods were used to improve the adhesion of the CaCO{sub 3} fibers. • The CaCO{sub 3} fibers were converted to hydroxyapatite by treatment in phosphate solution. • The hydroxyapatite fibers consisted of plate-like nanocrystals.

  18. Choroid vascular occlusion and ischemic optic neuropathy after facial calcium hydroxyapatite injection- a case report

    OpenAIRE

    Chou, Chien-Chih; Chen, Hsin-Han; Tsai, Yi-Yu; Li, You-Ling; Lin, Hui-Ju

    2015-01-01

    Background We reported a case of sudden monocular vision loss after calcium hydroxyapatite (CaHA) injection into the nasal tip and dorsum with detailed retina images. Case presentation A healthy, 35-year-old woman received CaHA filler injection for nose augmentation. Ten minutes after the procedure, she developed nausea, vomiting, headache, ptosis, and left periorbital pain. After 30?minutes, she complained of progressively blurring vision in the left eye. The best-corrected visual acuity (BC...

  19. Electrospinning of calcium carbonate fibers and their conversion to nanocrystalline hydroxyapatite.

    Science.gov (United States)

    Holopainen, Jani; Santala, Eero; Heikkilä, Mikko; Ritala, Mikko

    2014-12-01

    Calcium carbonate (CaCO3) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO3 fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO3 layer by spin or dip coating Ca(NO3)2/PVP precursor solution on the CaCO3 fibers followed by annealing of the gel formed inside the fiber layer. The CaCO3 fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Biomechanical Comparisons of Pull Out Strengths After Pedicle Screw Augmentation with Hydroxyapatite, Calcium Phosphate, or Polymethylmethacrylate in the Cadaveric Spine.

    Science.gov (United States)

    Yi, Seong; Rim, Dae-Cheol; Park, Seoung Woo; Murovic, Judith A; Lim, Jesse; Park, Jon

    2015-06-01

    In vertebrae with low bone mineral densities pull out strength is often poor, thus various substances have been used to fill screw holes before screw placement for corrective spine surgery. We performed biomechanical cadaveric studies to compare nonaugmented pedicle screws versus hydroxyapatite, calcium phosphate, or polymethylmethacrylate augmented pedicle screws for screw tightening torques and pull out strengths in spine procedures requiring bone screw insertion. Seven human cadaveric T10-L1 spines with 28 vertebral bodies were examined by x-ray to exclude bony abnormalities. Dual-energy x-ray absorptiometry scans evaluated bone mineral densities. Twenty of 28 vertebrae underwent ipsilateral fluoroscopic placement of 6-mm holes augmented with hydroxyapatite, calcium phosphate, or polymethylmethacrylate, followed by transpedicular screw placements. Controls were pedicle screw placements in the contralateral hemivertebrae without augmentation. All groups were evaluated for axial pull out strength using a biomechanical loading frame. Mean pedicle screw axial pull out strength compared with controls increased by 12.5% in hydroxyapatite augmented hemivertebrae (P = 0.600) and by 14.9% in calcium phosphate augmented hemivertebrae (P = 0.234), but the increase was not significant for either method. Pull out strength of polymethylmethacrylate versus hydroxyapatite augmented pedicle screws was 60.8% higher (P = 0.028). Hydroxyapatite and calcium phosphate augmentation in osteoporotic vertebrae showed a trend toward increased pedicle screw pull out strength versus controls. Pedicle screw pull out force of polymethylmethacrylate in the insertion stage was higher than that of hydroxyapatite. However, hydroxyapatite is likely a better clinical alternative to polymethylmethacrylate, as hydroxyapatite augmentation, unlike polymethylmethacrylate augmentation, stimulates bone growth and can be revised. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Preparation and structure of carbonated calcium hydroxyapatite substituted with heavy rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Yasukawa, Akemi, E-mail: yasukawa@cc.hirosaki-u.ac.jp [School of Home Economics, Faculty of Education, Hirosaki University, 1-bunkyo, Hirosaki, Aomori 036-8560 (Japan); Kandori, Kazuhiko [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Tanaka, Hidekazu [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Gotoh, Keiko [Faculty of Human Life and Environment, Nara Women' s University, Kita-uoya-nishi, Nara 630-8506 (Japan)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer LnCaHap solid solution particles were prepared using five types of heavy rare earth ions by a precipitation method. Black-Right-Pointing-Pointer The length and the crystallinity of the LnCaHap particles first increased and then decreased with increasing Ln{sup 3+} contents. Black-Right-Pointing-Pointer A series of YCaHap solid solution particles formed with Y/(Y + Ca) = 0-0.10 were investigated using various methods in detail. -- Abstract: Calcium hydroxyapatite (CaHap) particles substituted five types of heavy rare earth ions (Ln: Y{sup 3+}, Gd{sup 3+}, Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+}) were synthesized using a precipitation method and characterized using various means. These Ln ions strongly affected the crystal phases and the structures of the products. With increasing Ln/(Ln + Ca) in the starting solution ([X{sub Ln}]), the length and the crystallinity of the particles first increased and then decreased. The rare earth metal-calcium hydroxyapatite (LnCaHap) solid solution particles were obtained at [X{sub Y}] {<=} 0.10 for substituting Y system and at [X{sub Ln}] {<=} 0.01-0.03 for substituting the other Ln systems. LnPO{sub 4} was mixed with LnCaHap at higher [X{sub Ln}] for all Ln systems. A series of yttrium-calcium hydroxyapatite (YCaHap) solid solutions with [X{sub Y}] = 0-0.10 were investigated using XRD, TEM, ICP-AES, IR and TG-DTA in detail.

  2. Optimising calcium monitoring post thyroid and parathyroid surgery.

    Science.gov (United States)

    Rayner, Eleanor; Williams, Nerida; Dunn, Julie

    2014-01-01

    There is a risk of hypocalcaemia following total thyroidectomy and parathyroidectomy surgery, with the nadir being two to five days post operatively.[1] This project examined and improved the post-operative monitoring of serum calcium in patients undergoing these procedures at the Royal Devon and Exeter (RD&E) Hospital over a ten month period in 2013. A retrospective audit was undertaken, identifying whether serum calcium was monitored according to guideline; ie measured within the first 24 hours of surgery and daily thereafter until the patient was normocalcaemic.[2-3] The audit showed an overall compliance in 79% (n = 34) of cases. Of the non-compliant cases (n=9), seven also suffered hypocalcaemia. The current process was mapped by a flow chart and used as a basis for discussing experiences and identifying areas for improvement. Interventions implemented included a patient leaflet, a process flow chart displayed in the team office and in the weekend handover book, standard text for use in discharge summaries describing the process to GPs, the issuing of prescriptions or actual supplements for patients felt to be at high risk of hypocalcaemia, and finally education to the wider surgical junior doctor team. Percentage compliance with guidelines was compared before and after intervention with a re-audit undertaken in April 2014. Significant improvement was shown, with 100% of re-audit cases compliant (n=41), and all seven cases of hypocalcaemia were managed in full compliance with guideline.

  3. In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Yinfu; Huang, Yanlin; Qi, Shuyun [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Chen, Cuili [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-10-01

    A novel calcium silicate borate Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics were also measured, which indicate that the biomaterials based on Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si–OH) and B–OH groups can be easily induced on the surface of Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics soaked in SBF solutions. - Highlights: • Calcium silicate borate Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics were developed as a new biomaterial. • Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} shows a superior in vitro bioactivity by inducing bone-like apatite. • Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} has good mechanical properties as potential candidate biomaterials. • The structure with SiO{sub 4} and BO{sub 3} groups is favorable for hydroxyapatite formation.

  4. Evidence of a Lead Metathesis Product from Calcium Hydroxyapatite Dissolution in Lead Nitrate Solution

    Directory of Open Access Journals (Sweden)

    Oratai Saisa-ard

    2014-01-01

    Full Text Available Calcium hydroxyapatite, CaHAp, synthesized by the precipitation method, was utilized to study the calcium-lead metathesis reaction on dissolution in a lead nitrate solution under reflux conditions to prepare larger lead hydroxyapatite, PbHAp, crystals from CaHAp. SEM images show development of crystalline PbHAp on the surfaces of CaHAp. The needle-like crystal morphology observed for PbHAp after 24 h reaction time developed into hexagonal-rod crystal morphology within 48 h reaction time. The largest PbHAp crystals obtained from 48 h reaction time have approximate size of 10 × 10 × 40 μm. Powder X-ray diffraction results show mixed phases of CaHAp and PbHAp due to difficulty in separating the PbHAp product from the CaHAp substrate. The PbHAp peaks observed after 24 h of reaction sharpen and increase in intensity after 48 h of reaction confirming that the PbHAp phase is the major product for the 48 h reaction time. EDX results of the crystalline products show high intensity Pb peaks with lead to phosphorous ratio (5 : 3 as expected for PbHAp. Lower intensity Ca peaks are also observed, consistent with incomplete coverage of the CaHAp growth substrate.

  5. Muscle as an osteoinductive niche for local bone formation with the use of a biphasic calcium sulphate/hydroxyapatite biomaterial

    DEFF Research Database (Denmark)

    Raina, D. B.; Gupta, A.; Petersen, M. M.

    2016-01-01

    Objectives: We have observed clinical cases where bone is formed in the overlaying muscle covering surgically created bone defects treated with a hydroxyapatite/calcium sulphate biomaterial. Our objective was to investigate the osteoinductive potential of the biomaterial and to determine if growth...... as an osteoinductive niche, and provides the required cells for bone formation....

  6. A Biphasic Calcium Sulphate/Hydroxyapatite Carrier Containing Bone Morphogenic Protein-2 and Zoledronic Acid Generates Bone

    DEFF Research Database (Denmark)

    Raina, Deepak Bushan; Isaksson, Hanna; Hettwer, Werner

    2016-01-01

    -the-shelf osteoinductive bone substitutes that can replace bone grafts are required. We tested the carrier properties of a biphasic, calcium sulphate and hydroxyapatite ceramic material, containing a combination of recombinant human bone morphogenic protein-2 (rhBMP-2) to induce bone, and zoledronic acid (ZA) to delay...

  7. Bone healing around nanocrystalline hydroxyapatite, deproteinized bovine bone mineral, biphasic calcium phosphate, and autogenous bone in mandibular bone defects

    DEFF Research Database (Denmark)

    Broggini, Nina; Bosshardt, Dieter D; Jensen, Simon S

    2015-01-01

    with nanocrystalline hydroxyapatite (HA-SiO), deproteinized bovine bone mineral (DBBM), biphasic calcium phosphate (BCP) with a 60/40% HA/β-TCP (BCP 60/40) ratio, or particulate autogenous bone (A) for histological and histomorphometric analysis. At 2 weeks, percent filler amongst the test groups (DBBM (35.65%), HA...

  8. Active protein and calcium hydroxyapatite bilayers grown by laser techniques for therapeutic applications.

    Science.gov (United States)

    Motoc, M M; Axente, E; Popescu, C; Sima, L E; Petrescu, S M; Mihailescu, I N; Gyorgy, E

    2013-09-01

    Active protein and bioceramic calcium hydroxyapatite (HA) bilayers were grown by combining conventional pulsed laser deposition (PLD) and matrix-assisted pulsed laser evaporation (MAPLE) techniques. A pulsed UV KrF* excimer laser was used for the irradiations. The HA layers were grown by PLD. Proteins with antimicrobial action were attached to the bioceramic layers using MAPLE. The composite MAPLE targets were obtained by dissolving the proteins powder in distilled water. The crystalline status and chemical composition of the obtained structures were studied by X-ray diffractometry and Fourier transform infrared spectroscopy. The layers were grown for the design of advanced future metal implants coatings, ensuring both enhanced bone formation and localized antimicrobial therapy. Our results demonstrated that protein coatings improve bone cell proliferation in vitro. Immunofluorescence experiments show that actin filaments stretch throughout bone cells and sustain their optimal spreading. Copyright © 2013 Wiley Periodicals, Inc.

  9. Tunable Degradation Rate and Favorable Bioactivity of Porous Calcium Sulfate Scaffolds by Introducing Nano-Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Jianhua Zhou

    2016-12-01

    Full Text Available The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4 scaffolds were fabricated successfully via selected laser sintering (SLS. Nano-hydroxyapatite (nHAp, a bioactive material with a low degradation rate, was introduced into CaSO4 scaffolds to overcome the overquick absorption. The results demonstrated that nHAp could not only control the degradation rate of scaffolds by adjusting their content, but also improve the pH environment by alleviating the acidification progress during the degradation of CaSO4 scaffolds. Moreover, the improved scaffolds were covered completely with the apatite spherulites in simulated body fluid (SBF, showing their favorable bioactivity. In addition, the compression strength and fracture toughness were distinctly enhanced, which could be ascribed to large specific area of nHAp and the corresponding stress transfer.

  10. Removal of Pb (II from Aqueous Solutions Using Mixtures of Bamboo Biochar and Calcium Sulphate, and Hydroxyapatite and Calcium Sulphate

    Directory of Open Access Journals (Sweden)

    Ahmed Hassan

    2016-01-01

    Full Text Available Sorption characteristics of Pb(II from aqueous solutions through a low-cost adsorbent mixture comprising of Bamboo biochar (BB and Calcium Sulphate (CS, and a more expensive mixture of Hydroxyapatite (HAP and Calcium Sulphate (CS, were investigated. The effects of equilibrium contact time, and adsorbate concentration conducted in batch experiments were studied. Adsorption equilibrium was established in 40 (min. The adsorption mechanism of Pb(II from these two adsorbent mixtures was carried out through a kinetic rate order. A pseudo second-order kinetic model was applied for the adsorption processes. The model yielded good correlation (R2 >0.999 of the experimental data. Adsorption of Pb(II using (BB&CS and (HAP&CS correlated well (R2 >0.99 with both the Langmuir and Freundlich isotherm equations under the concentration range studied. Hence, the effectiveness of an inexpensive natural material (BB&CS mixture in Pb(II removal is established, and is promising for use in other heavy metal adsorptions.

  11. Effect of Calcium-Infiltrated Hydroxyapatite Scaffolds on the Hematopoietic Fate of Human Umbilical Vein Endothelial Cells.

    Science.gov (United States)

    Zhang, Qinghao; Gerlach, Jörg C; Schmelzer, Eva; Nettleship, Ian

    2017-01-01

    Foamed hydroxyapatite offers a three-dimensional scaffold for the development of bone constructs, mimicking perfectly the in vivo bone structure. In vivo, calcium release at the surface is assumed to provide a locally increased gradient supporting the maintenance of the hematopoietic stem cells niche. We fabricated hydroxyapatite scaffolds with high surface calcium concentration by infiltration, and used human umbilical vein endothelial cells (HUVECs) as a model to study the effects on hematopoietic lineage direction. HUVECs are umbilical vein-derived and thus possess progenitor characteristics, with a prospective potential to give rise to hematopoietic lineages. HUVECs were cultured for long term on three-dimensional porous hydroxyapatite scaffolds, which were either infiltrated biphasic foams or untreated. Controls were cultured in two-dimensional dishes. The release of calcium into culture medium was determined, and cells were analyzed for typical hematopoietic and endothelial gene expressions, surface markers by flow cytometry, and hematopoietic potential using colony-forming unit assays. Our results indicate that the biphasic foams promoted a hematopoietic lineage direction of HUVECs, suggesting an improved in vivo-like scaffold for hematopoietic bone tissue engineering. © 2017 S. Karger AG, Basel.

  12. Degradable biocomposite of nano calcium-deficient hydroxyapatite-multi(amino acid) copolymer

    Science.gov (United States)

    Li, Hong; Gong, Min; Yang, Aiping; Ma, Jian; Li, Xiangde; Yan, Yonggang

    2012-01-01

    Background and methods A nano calcium-deficient hydroxyapatite (n-CDHA)-multi(amino acid) copolymer (MAC) composite bone substitute biomaterial was prepared using an in situ polymerization method. The composition, structure, and compressive strength of the composite was characterized, and the in vitro degradability in phosphate-buffered solution and preliminary cell responses to the composite were investigated. Results The composite comprised n-CDHA and an amide linkage copolymer. The compressive strength of the composite was in the range of 88–129 MPa, varying with the amount of n-CDHA in the MAC (ranging from 10 wt% to 50 wt%). Weight loss from the composite increased (from 32.2 wt% to 44.3 wt%) with increasing n-CDHA content (from 10 wt% to 40 wt%) in the MAC after the composite was soaked in phosphate-buffered solution for 12 weeks. The pH of the soaking medium varied from 6.9 to 7.5. MG-63 cells with an osteogenic phenotype were well adhered and spread on the composite surface. Viability and differentiation increased with time, indicating that the composite had no negative effects on MG-63 cells. Conclusion The n-CDHA-MAC composite had good cytocompatibility and has potential to be used as a bone substitute. PMID:22457591

  13. Electronic structure and bonding in calcium apatite crystals: Hydroxyapatite, fluorapatite, chlorapatite, and bromapatite

    Science.gov (United States)

    Rulis, Paul; Ouyang, Lizhi; Ching, W. Y.

    2004-10-01

    We present a detailed analysis of the electronic structure, bonding, charge transfer, and optical properties of selected perfect-crystal calcium apatites [ Ca10(PO4)6X2 with X=(OH)-,F-,Cl- , or Br- ]. The ab initio orthogonalized linear combinations of atomic orbitals-density-functional-theory-based computational method is used to obtain the band structure, total and partial density of states, bond order, Mulliken effective charge, dielectric constant, and energy-loss function for each system. Band results indicate that these materials are all wide band-gap insulators in the range of ˜5.3eV . The bonding results show that the systems are dominated by two sets of structures: a PO4 sublattice and Ca channels populated by ion columns of X . The exact positions and orientations of the ions in the Ca channels are subject to debate on many levels. To contribute to the discussion, we analyze the position and orientation of the hydroxyl group from hydroxyapatite along the Ca channel using total-energy comparisons.

  14. Calcium pyrophosphate dihydrate and hydroxyapatite crystals in a patient with rheumatoid arthritis: Acase report

    Directory of Open Access Journals (Sweden)

    Shereen R Kamel

    2017-01-01

    Full Text Available The association between rheumatoid arthritis (RA and calcium pyrophosphate dihydrate (CPPD crystal deposits can now be easily identified by MSUS, which is a noninvasive technique that can be applied to patients with painful joints and enthesis that are unexplained by rheumatoid activity. In this paper, we report an Egyptian case of a 51-year-old man who had rheumatoid arthritis since 7 years and developed bilateral knee and heel pain of 1.5 months’ duration with gradual onset and progressive course. Radiography revealed features of RA in both hands, as well as features of severe osteoarthritis in both knees with no signs of chondrocalcinosis. Ultrasonography of the joints, Achilles tendon, and plantar fascia detected knee, Achilles tendon, and plantar fascia calcifications, which are characteristic of CPPD, and supraspinatus calcification, which is characteristic of hydroxyapatite (HA deposition. Further investigations revealed no evidence of metabolic disorders. CPPD and HA crystals were identified in his synovial fluid. Subclinical affection with CPPD and HA crystals in RA can be easily detected by ultrasonography, which allows early management to prevent future attacks in RA patients that could lead to exacerbation of joint symptoms that may be missed as rheumatoid disease activity. Diet control and colchicine treatment may be more effective if started early before exacerbation.

  15. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yufu, E-mail: Yufu.Ren@rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Nabiyouni, Maryam [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10 min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7 days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5 days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. - Highlights: • A microwave assisted coating process for biodegradable Mg alloy. • CDHA coatings were successfully developed on AZ31 alloy in minutes. • The as-deposited CDHA coatings significantly reduced the degradation rate of AZ31 alloy. • The CDHA coated AZ31 alloy showed good bioactivity and biocompatibility in vitro. • The microwave assisted coating process can be used as rapid surface modification for bioimplants.

  16. Calcium hydroxyapatite-based photocatalysts for environment remediation: Characteristics, performances and future perspectives.

    Science.gov (United States)

    Piccirillo, C; L Castro, P M

    2017-05-15

    Calcium hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is a material widely used in biomedicine, for bone implants manufacture, due to its biocompatibility. HAp has also application for environmental remediation, as it can be employed as metal removal; moreover, it has the capability of effectively adsorbing organic molecules its surface. In recent years, the photocatalytic properties of HAp have been investigated; indeed several studies report of HAp used as photocatalyst, either on its own or combined with other photocatalytic materials. Although in the majority of cases the activity was induced by UV light, some reports of visible light-activated materials were reported. Here we present a critical review of the latest developments for HAp-based photocatalysts; the materials discussed are undoped single phase HAp, doped HAp and HAp-containing composites. For undoped single phase HAp, the possible surface treatment and lattice defects which can lead to a photoactive material are discussed. Considering doped HAp, the use of Ti4+ (the most common dopant) is described, with particular attention to the effects that this metal have on the characteristics of the material (i.e. crystallinity) and on its photocatalytic behaviour. The use of other dopants is also discussed. For the multiphasic materials, the combination of HAp with other photocatalysts is discussed, mainly but not only with titanium dioxide TiO2. Overall, HAp is a compound with high potential as photocatalyst; this property, combined with its capability for heavy metal removal, makes it a multifunctional material for environmental remediation. As future perspectives, further studies, based on the results obtained until present, should be performed, to improve the performance of the materials and/or shift the band gap into the visible. The use of other dopants and/or the combination with other photocatalysts, for instance, are features which is worth exploring. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Effect of ammonium carbonate on formation of calcium-deficient hydroxyapatite through double-step hydrothermal processing.

    Science.gov (United States)

    Parthiban, S Prakash; Kim, Ill Yong; Kikuta, Koichi; Ohtsuki, Chikara

    2011-02-01

    Double-step hydrothermal processing is a process where powder compacts of calcium phosphates are exposed to vapor of solvent solution, followed by being immersed in the solution. In the present study, we investigated the effects of ammonium carbonate on formation of calcium-deficient hydroxyapatite (CDHA) through double-step hydrothermal processing. The synthesized CDHA has high crystallinity when the solution has relatively low concentration of the ammonium carbonate ranging from 0.01 to 0.25 mol dm(-3). Carbonate content in the prepared samples were distinctly increased with increasing the concentration of ammonium carbonate to indicate formation of carbonate-containing calcium-deficient hydroxyapatite (CHAp) with low crystallinity. Morphology of the CHAp formed on the compacts varied progressively from rods and rosette-like shape to irregular shape with increase in the initial concentration of the ammonium carbonate in the solution. Application of ammonium carbonate in the double-step hydrothermal processing allows fabrication of irregular-shaped CDHA containing carbonate ions in both phosphate and hydroxide site, with low crystallinity, when the initial concentration of ammonium carbonate was 0.5 mol dm(-3) and more.

  18. In-situ observation of the transformation of amorphous calcium phosphate to crystalline hydroxyapatite

    Science.gov (United States)

    Stammeier, Jessica; Hippler, Dorothee; Mavromatis, Vasileios; Sacher, Stephan; Dietzel, Martin

    2016-04-01

    Amorphous calcium phosphate (Ca3(PO4)2*nH2O; ACP) is often a precursor phase of the mineral (hydroxy-) apatite (Ca5(PO4)3(OH)) that can be formed in natural settings during both authigenic and biogenic mineral formation. Particularly, in the biomineralization process of fish tissue, ACP has shown to be an important transient phase. In solution ACP rapidly transforms into the crystalline phase. The transformation rate highly depends on the physico-chemical conditions of the solution: Ca & P availability, pH and temperature. In natural settings Ca can be provided by different sources: from (1) seawater, (2) porewater, or (3) diagenetically-altered carbonates, whereas local supersaturation of P can be induced by microbial activity. In this study, we performed phosphate precipitation experiments in order to monitor the transformation process of the ACP to crystalline hydroxyapatite (HAP) using in-situ Raman spectroscopy. During the experiments the temperature was kept constant at 20.0 ± 0.01 ° C and pH at 9 ± 0.1. 50 ml of 0.3 CaCl 2H2O was titrated at a rate of 5 ml/min to an equal volume of 0.2 M Na2HPO4. The pH was kept constant by titration of 1 M NaOH. During the experiment samples were taken from the solution and instantly filtered. The obtained solid samples were lyophilized and analyzed with XRD, ATR and SEM. The respective solution samples were analyzed using ion chromatography and ICP OES, coupling the spectroscopic data with detailed solution chemistry data. We observed transformation of ACP to HAP to occur within 14 hours, illustrated in a clear peak shift in Raman spectra from 950 cm-1 to 960 cm-1. The obtained results are discussed in the aspects of distribution of major elements during the formation of phosphates and/or the diagenetic alteration of carbonates to phosphates in geologic settings. Financial support by DFG-FG 736 and NAWI Graz is kindly acknowledged.

  19. In vivo biocompatibility of new nano-calcium-deficient hydroxyapatite/poly-amino acid complex biomaterials.

    Science.gov (United States)

    Dai, Zhenyu; Li, Yue; Lu, Weizhong; Jiang, Dianming; Li, Hong; Yan, Yonggang; Lv, Guoyu; Yang, Aiping

    2015-01-01

    To evaluate the compatibility of novel nano-calcium-deficient hydroxyapatite/poly-amino acid (n-CDHA/PAA) complex biomaterials with muscle and bone tissue in an in vivo model. Thirty-two New Zealand white rabbits were used in this study. Biomaterials were surgically implanted into each rabbit in the back erector spinae and in tibia with induced defect. Polyethylene was implanted into rabbits in the control group and n-CDHA/PAA into those of the experimental group. Animals were examined at four different points in time: 2 weeks, 4 weeks, 12 weeks, and 24 weeks after surgery. They were euthanized after embolization. Back erector spinae muscles with the surgical implants were examined after hematoxylin and eosin (HE) staining at these points in time. Tibia bones with the surgical implants were examined by X-ray and scanning electron microscopy (SEM) at these points in time to evaluate the interface of the bone with the implanted biomaterials. Bone tissues were sectioned and subjected to HE, Masson, and toluidine blue staining. HE staining of back erector spinae muscles at 4 weeks, 12 weeks, and 24 weeks after implantation of either n-CDHA/PAA or polyethylene showed disappearance of inflammation and normal arrangement in the peripheral tissue of implant biomaterials; no abnormal staining was observed. At 2 weeks after implantation, X-ray imaging of bone tissue samples in both experimental and control groups showed that the peripheral tissues of the implanted biomaterials were continuous and lacked bone osteolysis, absorption, necrosis, or osteomyelitis. The connection between implanted biomaterials and bone tissue was tight. The results of HE, Masson, toluidine blue staining and SEM confirmed that the implanted biomaterials were closely connected to the bone defect and that no rejection had taken place. The n-CDHA/PAA biomaterials induced differentiation of a large number of chondrocytes. New bone trabecula began to form at 4 weeks after implanting n

  20. Specialized probes based on hydroxyapatite calcium for heart tissues research by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhukov, Mikhail, E-mail: cloudjyk@yandex.ru; Golubok, Alexander [St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University), Kronverkskii pr. 49, St. Petersburg, 197101 (Russian Federation); Institute for Analytical Instrumentation, Russian Academy of Sciences (RAS), Rizhskii pr. 26, St. Petersburg, 190103 (Russian Federation); Gulyaev, Nikolai [Military Medical Academy named after S.M. Kirov, Academic Lebedev str. 6, St. Petersburg, 194044 (Russian Federation)

    2016-06-17

    The new specialized AFM-probes with hydroxyapatite structures for atomic force microscopy of heart tissues calcification were created and studied. A process of probe fabrication is demonstrated. The adhesive forces between specialized hydroxyapatite probe and endothelium/subendothelial layers were investigated. It was found that the adhesion forces are significantly higher for the subendothelial layers. We consider that it is connected with the formation and localization of hydroxyapatite in the area of subendothelial layers of heart tissues. In addition, the roughness analysis and structure visualization of the endothelial surface of the heart tissue were carried out. The results show high efficiency of created specialized probes at study a calcinations process of the aortic heart tissues.

  1. The influence of silicon substitution on the properties of spherical- and whisker-like biphasic α-calcium-phosphate/hydroxyapatite particles.

    Science.gov (United States)

    Jokic, B; Mitric, M; Popovic, M; Sima, L; Petrescu, S M; Petrovic, R; Janackovic, Dj

    2011-10-01

    In this work, the influence of the morphology of hydroxyapatite particles on silicon substitution through hydrothermal synthesis performed under the same conditions was investigated. Spherical- and whisker-like hydroxyapatite particles were obtained starting from calcium-nitrate, sodium dihydrogen phosphate, disodium-ethylenediaminetetraacetic acid and urea (used only for the synthesis of whisker-like particles) dissolved in aqueous solutions. Silicon was introduced into the solution using tetraethylorthosilicate. X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy indicate that silicon doping induce different phase compositions and bioactivity of spherical- and whisker-like hydroxyapatite particles obtained under the same hydrothermal conditions. Silicon-substituted, spherical hydroxyapatites particles showed greater phase transformation to silicon-substituted α- calcium-phosphate compared with whiskers-like hydroxyapatite particles synthesized with the same amount of added silicon. Metabolic activity assay performed with SaOs2 osteosarcoma cells showed better biocompatibility of annealed biphasic spherical-like particles compared with annealed whiskerlike particles while dried spherical-like particles induce high cytotoxicity effect.

  2. Synthesis of hydroxyapatite with the use of calcium carbonate as of the biological precursor; Sintese de hidroxiapatita com o uso de carbonato de calcio de origem biologica como precurssor

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, M.S.; Di Lello, B.C.; Queiroz, F.; Campos, N.C., E-mail: marilzasa@oi.com.br [Universidade Estacio de Sa (UESA), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia; Campos, J.B. [Universidade do Estado do Rio de Janeiro (PPGEM/UERJ), RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica

    2014-07-01

    This work describes the synthesis of hydroxyapatite from calcium from biological materials such as shells carbonate. In the syntheses performed, the calcium carbonate of biological origin was used as the precursor and through a precipitation reaction with phosphoric acid, was converted into calcium hydroxide. Sequentially, the precipitate was aged, filtered, washed, dried and calcined, and then transformed into hydroxyapatite. The characterization of the powders was performed by X-DR (X-ray diffraction) and SEM (scanning electron microscopy). DR-X as determined hydroxyapatite calcium phosphate phase calcium. SEM revealed a morphology of finely divided particles. The method B.E.T. showed values of specific area and volume of micropores consistent with the literature. The results of the characterizations proved feasible to use for obtaining biological hydroxyapatite materials used in the reaction conditions.(author)

  3. Preparation of calcium hydroxyapatite nanoparticles using microreactor and their characteristics of protein adsorption.

    Science.gov (United States)

    Kandori, Kazuhiko; Kuroda, Tomohiko; Togashi, Shigenori; Katayama, Erika

    2011-02-03

    The calcium hydroxyapatite Ca(10)(PO(4))(6)(OH)(2) (Hap) nanoparticles were prepared by using microreactor and employed these Hap nanoparticles to clarify the adsorption behavior of proteins. The size of Hap particles produced by the microreactor reduced in the order of a hardness of the reaction conditions for mixing Ca(OH)(2) and H(3)PO(4) aqueous solutions, such as flow rates of both solutions and temperature. Finally, the size of the smallest Hap nanoparticle became 2 × 15 nm(2), similar to that of BSA molecule (4 × 14 nm(2)). It is noteworthy that the smallest Hap nanoparticles still possesses rodlike shape, suggesting that particles are grown along c-axis even though the reactants mixed very rapidly in narrow channels of the microreactors. The X-ray diffraction patterns of the Hap nanoparticles revealed that the crystallinity of the materials produced by the microreactor is low. The FTIR measurement indicated that the Hap nanoparticles produced by microreactor were carbonate-substituted type B Hap, where the carbonate ions replace the phosphate ions in the crystal lattice. All the adsorption isotherms of acidic bovine serum albumin (BSA), neutral myoglobin (MGB), and basic lysozyme (LSZ) onto Hap nanoparticles from 1 × 10(-4) mol/dm(3) KCl solution were the Langmuirian type. The saturated amounts of adsorbed BSA (n(S)(BSA)) for the Hap nanoparticles produced by microreactor were decreased with decrease in the mean particle length, and finally it reduced to zero for the smallest Hap nanoparticles. Similar results were observed for the adsorption of LSZ; the saturated amounts of adsorbed LSZ (n(S)(LSZ)) also reduced to zero for the smallest Hap nanoparticles. However, in the case of MGB, the saturated mounts of adsorbed MGB (n(S)(MGB)) are also depressed with decreased in their particle size, but about half of MGB molecules still adsorbed onto the smallest Hap nanoparticles. This difference in the protein adsorption behavior was explained by the difference

  4. Strontium hydroxyapatite and strontium carbonate as templates for the precipitation of calcium-phosphates in the absence and presence of fluoride

    Science.gov (United States)

    Sternitzke, Vanessa; Janousch, Markus; Heeb, Michèle B.; Hering, Janet G.; Johnson, C. Annette

    2014-06-01

    The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.

  5. Self-hardening calcium deficient hydroxyapatite-gelatine foams for bone regeneration

    OpenAIRE

    Montufar Jiménez, Edgar Benjamin; Traykova, Tania; Schacht, Etienne; Ambrosio, Luigi; Santin, Matteo; Planell Estany, Josep Anton; Ginebra Molins, Maria Pau

    2009-01-01

    In this work gelatine was used as multifunctional additive to obtain injectable self-setting hydroxyapatite/ gelatine composite foams for bone regeneration. The foaming and colloidal stabilization properties of gelatine are well known in food and pharmaceutical applications. Solid foams were obtained by foaming liquid gelatine solutions at 50 C, followed by mixing them with a cement powder consisting of alpha tricalcium phosphate. Gelatine addition improved the cohesion and injectability of t...

  6. Evaluation of hydroxyapatite (Periobone-G) as a bone graft material and calcium sulfate barrier (Capset) in treatment of interproximal vertical defects: A clinical and radiologic study

    Science.gov (United States)

    Gupta, Sanjay; Vandana, K. L.

    2013-01-01

    Background: This study has been undertaken to assess treatment response of interproximal vertical defects using an alloplast (Periobone-G) and calcium sulfate (Capset) as a barrier both clinically and radiographically. Materials and Methods: Eight patients were selected with 16 sites that were divided into control and experimental sites based on split mouth study design. Plaque index, gingival index, probing depth, clinical attachment level, gingival margin position were recorded at baseline and 9 months and radiographic assessment was done at baseline and 9 months after recording clinical parameters, the sites were randomly treated either with hydroxyapatite granules Periobone-G or hydroxyapatite granules (control group) was used to fill the osseous defect and calcium sulfate (Capset) (experiment group) barrier was placed. Result: The plaque score reduction was statistically highly significant within control and experimental groups. The gingival score reduction was significant within control and experimental groups, although there were no significant difference between the 2 groups. The pocket depth reduction was significant within control and experimental group, however, the hydroxyapatite + capset group showed significant reduction as compared with hydroxyapatite alone group. The clinical attachment gain and gingival margin position was significant within control and experimental groups, although there was no significant difference between the 2 groups. The amount of defect fill was significant in both control and experimental groups but the difference between the 2 groups was not significant. The mean change in alveolar crest level between control and experimental groups was significant (P=0.02). The percentage of original defect resolved was not significant. Conclusion: The use of calcium sulfate as a barrier proved its role in the treatment of interproximal defects. The application of calcium sulfate (Capset) barrier is easy and simple. The multifaceted

  7. Optimisation of nutritional requirements for dopamine synthesis by calcium alginate-entrapped mutant strain of Aspergillus oryzae EMS-6.

    Science.gov (United States)

    Ali, Sikander; Nawaz, Wajeeha

    2017-02-01

    The optimisation of nutritional requirements for dopamine (DA) synthesis by calcium alginate-entrapped mutant variant of Aspergillus oryzae EMS-6 using submerged fermentation technique was investigated. A total of 13 strains were isolated from soil. Isolate I-2 was selected as a better producer of DA and improved by exposing with ethyl methylsulphonate (EMS). EMS-6 was selected as it exhibited 43 μg/mL DA activity. The mutant variable was further treated with low levels of l-cysteine HCl to make it resistant against diversion and environmental stress. The conidiospores of mutant variant were entrapped in calcium alginate beads for stable product formation. EMS-6 gave maximum DA activity (124 μg/mL) when supplemented with 0.1% peptone and 0.2% sucrose, under optimised parameters viz. pH 3, temperature of 55 °C and incubation time of 70 min. The study involves the high profile of DA activity and is needed, as DA is capable to control numerous neurogenic disorders.

  8. Identification of monoclinic calcium pyrophosphate dihydrate and hydroxyapatite in human sclera using Raman microspectroscopy

    DEFF Research Database (Denmark)

    Chen, Ko-Hua; Li, Mei-Jane; Cheng, Wen-Ting

    2009-01-01

    Raman microspectroscopy was first used to determine the composition of a calcified plaque located at the pterygium-excision site of a 51-year-old female patient's left nasal sclera after surgery. It was unexpectedly found that the Raman spectrum of the calcified sample at 1149, 1108, 1049, 756, 5...... to the characteristic peak at 958/cm of hydroxyapatite (HA). This is the first study to report the spectral biodiagnosis of both monoclinic CPPD and HA co-deposited in the calcified plaque of a patient with sclera dystrophic calcification using Raman microspectroscopy....

  9. Development and characterization of an injectable cement of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer/calcium sulfate hemihydrate for bone repair

    Science.gov (United States)

    Qi, Xiaotong; Li, Hong; Qiao, Bo; Li, Weichao; Hao, Xinyan; Wu, Jun; Su, Bao; Jiang, Dianming

    2013-01-01

    A novel injectable bone cement was developed by integration of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer (n-CDHA/MAC) and calcium sulfate hemihydrate (CSH; CaSO4 · 1/2H2O). The structure, setting time, and compressive strength of the cement were investigated. The results showed that the cement with a liquid to powder ratio of 0.8 mL/g exhibited good injectability and appropriate setting time and mechanical properties. In vitro cell studies indicated that MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite spread well and showed a good proliferation state. The alkaline phosphatase activity of the MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite was significantly higher than that of the cells on pure CSH at 4 and 7 days of culture. The n-CDHA/MAC/CSH cement was implanted into critical size defects of the femoral condyle in rabbits to evaluate its biocompatibility and osteogenesis in vivo. Radiological and histological results indicated that introduction of the n-CDHA/MAC into CSH enhanced new bone formation, and the n-CDHA/MAC/CSH cement exhibited good biocompatibility and degradability. In conclusion, the injectable n-CDHA/MAC/CSH composite cement has a significant clinical advantage over pure CSH cement, and may be a promising bone graft substitute for the treatment of bone defects. PMID:24293996

  10. Comparative evaluation of Nano-Hydroxyapatite preparation and Calcium Sucrose Phosphate on microhardness of deciduous teeth after iron drop exposure - An in-vitro study

    OpenAIRE

    Rathi, Nilesh; Baid, Rutika; Baliga, Sudhindra; Thosar, Nilima

    2017-01-01

    Background To evaluate and compare the microhardness of deciduous teeth treated with nano-hydroxyapatite and calcium sucrose phosphate after iron drop exposure. Material and Methods Twenty healthy anterior deciduous teeth were collected and stored in 0.9% saline solution at room temperature. All the teeth were immersed in artificial saliva in an incubator shaker at 37? for an hour and then subjected to Vickers microhardness test at 100g load for 5 seconds. The teeth were then immersed in iron...

  11. Comparative evaluation of Nano-hydroxyapatite and casein Phosphopeptide-amorphous calcium phosphate on the remineralization potential of early enamel lesions: An in vitro study

    Directory of Open Access Journals (Sweden)

    Anshul Sharma

    2017-01-01

    Full Text Available Background: Benefits of remineralizing agents in a wide variety of formulations have been proved beneficial in caries management. Casein phosphopeptide-amorphous calcium phosphate (CPP–ACP nanocomplex has been recommended and used as remineralizing agent. Nano-hydroxyapatite (n-HAp is one of the most biocompatible and bioactive material having wide range of application in dentistry, but does it excel better compared to CPP-ACP. Aims: To evaluate and compare the remineralizing efficiency of the paste containing hydroxyapatite and casein phosphopeptide-amorphous calcium phosphate. Settings and Design: The study was an in vitro single blinded study with lottery method of randomization approved by the Institutional Ethics Committee. Materials and methods: 30 non carious premolar teeth. The teeth were demineralized and divided into 2 groups and subjected to remineralization. The samples were analysed for surface hardness and mineral content. Statistical Analysis: Student t’ test and repeated measures of ANOVA was applied. Results: Average hardness in Nano-hydroxyapatite group increased to 340 ± 31.70 SD and 426 ± 50.62 SD for 15 and 30 days respectively and that of (CPP–ACP, 355.83 ± 38.55 SD and 372.67 ± 53.63 SD. The change in the hardness values was not statistically significant with P value of 0.39 (P > 0.05. Calcium and Phosphorous levels increased in both the groups but was not significant. Conclusion: Both the agents used are effective in causing remineralization of enamel. Nano-hydroxyapatite is more effective as compared to Casein phosphopeptide-amorphous calcium phosphate, in increasing the Calcium and Phosphorus content of enamel, and this effect is more evident over a longer treatment period. Key Message: Remineralizing agents are a boon for caries management. With the advent of many formulations it is difficult to clinically select the agent. This study compares the remineralizing potential of Casein

  12. Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

    Science.gov (United States)

    Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

    2017-10-15

    Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this

  13. Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Marcos Antônio E.; Ruiz, Gilia C.M. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Faria, Amanda N. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Departamento de Bioquímica e Imunologia-Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Ramos, Ana P., E-mail: anapr@ffclrp.usp.br [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil)

    2016-05-01

    Graphical abstract: - Highlights: • CaCO{sub 3} continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO{sub 3} particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO{sub 3} deposited as thin films for this propose is unknown. Here, we report the growth of CaCO{sub 3} continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca{sup 2+}, exposed to CO{sub 2} (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO{sub 3} film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ{sub s}) were accessed. The presence of HAp increased the wettability and γ{sub s} of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO{sub 3} thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

  14. Magnesium substitution in the structure of orthopedic nanoparticles: A comparison between amorphous magnesium phosphates, calcium magnesium phosphates, and hydroxyapatites.

    Science.gov (United States)

    Nabiyouni, Maryam; Ren, Yufu; Bhaduri, Sarit B

    2015-01-01

    As biocompatible materials, magnesium phosphates have received a lot of attention for orthopedic applications. During the last decade multiple studies have shown advantages for magnesium phosphate such as lack of cytotoxicity, biocompatibility, strong mechanical properties, and high biodegradability. The present study investigates the role of Mg(+2) and Ca(+2) ions in the structure of magnesium phosphate and calcium phosphate nanoparticles. To directly compare the effect of Mg(+2) and Ca(+2) ions on structure of nanoparticles and their biological behavior, three groups of nanoparticles including amorphous magnesium phosphates (AMPs) which release Mg(+2), calcium magnesium phosphates (CMPs) which release Mg(+2) and Ca(+2), and hydroxyapatites (HAs) which release Ca(+2) were studied. SEM, TEM, XRD, and FTIR were used to evaluate the morphology, crystallinity, and chemical properties of the particles. AMP particles were homogeneous nanospheres, whereas CMPs were combinations of heterogeneous nanorods and nanospheres, and HAs which contained heterogeneous nanosphere particles. Cell compatibility was monitored in all groups to determine the cytotoxicity effect of particles on studied MC3T3-E1 preosteoblasts. AMPs showed significantly higher attachment rate than the HAs after 1 day and both AMPs and CMPs showed significantly higher proliferation rate when compared to HAs after 7days. Gene expression level of osteoblastic markers ALP, COL I, OCN, OPN, RUNX2 were monitored and they were normalized to GAPDH housekeeping gene. Beta actin expression level was monitored as the second housekeeping gene to confirm the accuracy of results. In general, AMPs and CMPs showed higher expression level of osteoblastic genes after 7 days which can further confirm the stimulating role of Mg(+2) and Ca(+2) ions in increasing the proliferation rate, differentiation, and mineralization of MC3T3-E1 preosteoblasts. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Effect of pyrophosphate ions on the conversion of calcium-lithium-borate glass to hydroxyapatite in aqueous phosphate solution.

    Science.gov (United States)

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

    2010-10-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium-lithium-borate glass to HA was investigated. Particles of the glass (150-355 μm) were immersed for up to 28 days in 0.25 M K(2)HPO(4) solution containing 0-0.1 M K(4)P(2)O(7). The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K(4)P(2)O(7) concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K(4)P(2)O(7)) to 10 days (0.01 M K(4)P(2)O(7)). When the K(4)P(2)O(7) concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K(2)CaP(2)O(7) and Ca(2)P(2)O(7)). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed.

  16. Strontium-Doped Calcium Phosphate and Hydroxyapatite Granules Promote Different Inflammatory and Bone Remodelling Responses in Normal and Ovariectomised Rats

    Science.gov (United States)

    Xia, Wei; Emanuelsson, Lena; Norlindh, Birgitta; Omar, Omar; Thomsen, Peter

    2013-01-01

    The healing of bone defects may be hindered by systemic conditions such as osteoporosis. Calcium phosphates, with or without ion substitutions, may provide advantages for bone augmentation. However, the mechanism of bone formation with these materials is unclear. The aim of this study was to evaluate the healing process in bone defects implanted with hydroxyapatite (HA) or strontium-doped calcium phosphate (SCP) granules, in non-ovariectomised (non-OVX) and ovariectomised (OVX) rats. After 0 (baseline), six and 28d, bone samples were harvested for gene expression analysis, histology and histomorphometry. Tumour necrosis factor-α (TNF-α), at six days, was higher in the HA, in non-OVX and OVX, whereas interleukin-6 (IL-6), at six and 28d, was higher in SCP, but only in non-OVX. Both materials produced a similar expression of the receptor activator of nuclear factor kappa-B ligand (RANKL). Higher expression of osteoclastic markers, calcitonin receptor (CR) and cathepsin K (CatK), were detected in the HA group, irrespective of non-OVX or OVX. The overall bone formation was comparable between HA and SCP, but with topological differences. The bone area was higher in the defect centre of the HA group, mainly in the OVX, and in the defect periphery of the SCP group, in both non-OVX and OVX. It is concluded that HA and SCP granules result in comparable bone formation in trabecular bone defects. As judged by gene expression and histological analyses, the two materials induced different inflammatory and bone remodelling responses. The modulatory effects are associated with differences in the spatial distribution of the newly formed bone. PMID:24376855

  17. Difference between dogs and rats with regard to osteoclast-like cells in calcium-deficient hydroxyapatite-induced osteoinduction.

    Science.gov (United States)

    Akiyama, Norihiro; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Neo, Masashi; Hirano, Masahiro; Nakamura, Takashi

    2011-02-01

    Material-induced osteoinduction is reported in comparatively large animals such as dogs and pigs; however, it does not often occur in small animals such as rodents. In this study, we implanted porous calcium-deficient hydroxyapatite (CDHA) in the dorsal muscles of dogs and rats and compared the two species, with emphasis on multinucleated cells, by using hematoxylin and eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) staining, transmission electron microscope (TEM) observation, and reverse transcription-polymerase chain reaction (RT-PCR). In CDHA extracted from dogs, numerous TRAP-positive multinucleated cells were detected after 2 weeks and new bone formation was observed after 4 weeks. In contrast, in rats, only a small number of TRAP-positive cells were detected and no bone formation was observed within 6 weeks. CDHA was more degraded in dogs than in rats. TEM observation of the multinucleated cells in CDHA extracted from dogs after 3 weeks revealed osteoclast-like features such as ruffled borders. However, CDHA extracted from rats did not exhibit osteoclast-like features. RT-PCR evaluation showed that the expression of cathepsin K was higher in dogs than in rats. These results indicate that TRAP-positive cells might be one of the main factors responsible for the cross-species difference in material-induced osteoinduction. 2010 Wiley Periodicals, Inc.

  18. Biological Assessment of a Calcium Silicate Incorporated Hydroxyapatite-Gelatin Nanocomposite: A Comparison to Decellularized Bone Matrix

    Directory of Open Access Journals (Sweden)

    Dong Joon Lee

    2014-01-01

    Full Text Available Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS. Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD. Twelve Sprague-Dawley rats were randomized to four groups: control (defect only, decellularized bone matrix (DECBM, and HGCS with and without multipotent adult progenitor cells (MAPCs. DECBM was prepared by removing all the cells using SDS and NH4OH. After 12 weeks, the CSD specimens were harvested to evaluate radiographical, histological, and histomorphometrical outcomes. The in vitro osteogenic effects of the materials were studied by focal adhesion, MTS, and alizarin red. Micro-CT analysis indicated that the DECBM and the HGCS scaffold groups developed greater radiopaque areas than the other groups. Bone regeneration, assessed using histological analysis and fluorochrome labeling, was the highest in the HGCS scaffold seeded with MAPCs. The DECBM group showed limited osteoinductivity, causing a gap between the implant and host tissue. The group grafted with HGCS+MAPCs resulting in twice as much new bone formation seems to indicate a role for effective bone regeneration. In conclusion, the novel HGCS scaffold could improve bone regeneration and is a promising carrier for stem cell-mediated bone regeneration.

  19. Osseointegration aspects of placed implant in bone reconstruction with newly developed block-type interconnected porous calcium hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Kazuya DOI

    Full Text Available ABSTRACT Artificial bone has been employed to reconstruct bone defects. However, only few reports on implant placement after block bone grafting exist. Objectives The purpose of this study was to evaluate the osseointegration of dental implant in bone reconstructions with interconnected porous calcium hydroxyapatite (IP-CHA. Material and Methods The IP-CHA cylinders (D; 4.3 mm, H; 10.0 mm were placed into bone sockets in each side of the femurs of four male dogs. The IP-CHA on the right side was a 24-week sample. Twelve weeks after placement, a titanium implant was placed into a socket that was prepared in half of the placed IP-CHA cylinder on the right side. On the left side, another IP-CHA cylinder was placed as a 12-week sample. After another 12 weeks, the samples were harvested, and the bone regeneration and bone-implant contact (BIC ratios were measured. Results New bone formation area was superior in the 24-week IP-CHA compared with the 12-week IP-CHA. BIC was not significantly different between IP-CHA and the parent sites. Osseointegration was detected around the implant in IP-CHA-reconstructed bone. Conclusion Our preliminary results suggest that IP-CHA may be a suitable bone graft material for reconstructing bones that require implant placement.

  20. X-ray diffraction investigation of amorphous calcium phosphate and hydroxyapatite under ultra-high hydrostatic pressure

    Science.gov (United States)

    Lam, Elisa; Gu, Qinfen; Swedlund, Peter J.; Marchesseau, Sylvie; Hemar, Yacine

    2015-11-01

    The changes in the crystal structures of synthetically prepared amorphous calcium phosphate (ACP) and hydroxyapatite (HAP) in water (1:1 mass ratio) were studied by synchrotron X-ray diffraction (XRD) under ultra-high hydrostatic pressures as high as 2.34 GPa for ACP and 4 GPa for HAP. At ambient pressure, the XRD patterns of the ACP and HAP samples in capillary tubes and their environmental scanning electron micrographs indicated amorphous and crystalline characteristics for ACP and HAP, respectively. At pressures greater than 0.25 GPa, an additional broad peak was observed in the XRD pattern of the ACP phase, indicating a partial phase transition from an amorphous phase to a new high-pressure amorphous phase. The peak areas and positions of the ACP phase, as obtained through fitting of the experimental data, indicated that the ACP exhibited increased pseudo-crystalline behavior at pressures greater than 0.96 GPa. Conversely, no structural changes were observed for the HAP phase up to the highest applied pressure of 4 GPa. For HAP, a unit-cell reduction during compression was evidenced by a reduction in both refined lattice parameters a and c. Both ACP and HAP reverted to their original structures when the pressure was fully released to ambient pressure.

  1. Development and characterization of a novel bioresorbable and bioactive biomaterial based on polyvinyl acetate, calcium carbonate and coralline hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Javier Aragón

    2011-03-01

    Full Text Available Coralina® HAP-200 (coralline hydroxyapatite obtained by hydrothermal treatment of marine corals and POVIAC® (polymeric matrix based on PVAc, commercial trade marks were mixed with a natural product from the Cuban sea costs, i.e. calcium carbonate from Porites Porites coral, to obtain a novel bioactive composite with potential use as bone restoration material. The samples were characterized by physical-chemical (FTIR, XRD, SEM, EDS and mechanical studies. It was shown that there is no chemical interaction between the inorganic filler and the polymer matrix, each conserving the original properties of the raw materials. The studied formulation had a compressive strength similar to that reported for trabecular bone. Scanning electron microscopy examination revealed that the addition of CaCO3 induces a change on the morphologic structure of the composite obtained after 30 days of SBF immersion. These composites generate novel biomaterials capable of promoting the deposition of a new phase, a Ca-P layer due to the bioactivity of a Ca2+ precursors.

  2. Effect of amorphous phases during the hydraulic conversion of α-TCP into calcium-deficient hydroxyapatite.

    Science.gov (United States)

    Hurle, Katrin; Neubauer, Juergen; Bohner, Marc; Doebelin, Nicola; Goetz-Neunhoeffer, Friedlinde

    2014-09-01

    Powders of α-tricalcium phosphate (α-TCP), which readily react with water to form calcium-deficient hydroxyapatite (CDHA), are frequently used in bone cements. As, for clinical applications, it is important to adjust the setting reaction of the cements to a reasonable reaction time, exact knowledge of the hydration mechanism is essential. It is known that prolonged milling results in partial amorphization of α-TCP powders and that dissolution of the amorphous phase significantly accelerates the hydration, but it is not clear yet when the amorphous phase reacts in comparison to the crystalline α-TCP. Therefore the aim of this study was to investigate the development of quantitative phase content of α-TCP samples during hydration. For this purpose, three α-TCP powders, containing 0, 16 and 71wt.% of amorphous phase (ATCP), were mixed with either deionized water or a 0.1M Na2HPO4 aqueous solution. The crystalline evolution of the paste was assessed quantitatively during the first 48h of hydration at 23°C by G-factor quantification. The present investigations demonstrate that ATCP reacted earlier than crystalline α-TCP. The results also suggest the formation of an X-ray amorphous phase during the hydraulic conversion formation of α-TCP into CDHA. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements

    Directory of Open Access Journals (Sweden)

    Juliane Maria GUERREIRO-TANOMARU

    Full Text Available ABSTRACT Objective Mineral Trioxide Aggregate (MTA is a calcium silicate cement composed of Portland cement (PC and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2 and hydroxyapatite nanoparticles (HAn. Material and Methods White MTA (Angelus, Brazil; PC (70%+ZrO2 (30%; PC (60%+ZrO2 (30%+HAn (10%; PC (50%+ZrO2 (30%+HAn (20% were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1 in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. Results There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10% and PC+ZrO2+HAn (20% (p>0.05 and these cements presented higher pH levels than MTA (p<0.05. The highest solubility was observed in PC+ZrO2+HAn (10% and PC+ZrO2+HAn (20% (p<0.05. MTA had the shortest initial setting time (p<0.05. All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05. Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05 after the post-manipulation period of 2 days. Conclusions The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%, the final setting time and

  4. TEM study of the morphology of Mn2+ -doped calcium hydroxyapatite and beta-tricalcium phosphate.

    Science.gov (United States)

    Mayer, I; Cuisinier, F J G; Gdalya, S; Popov, I

    2008-02-01

    Mn-doped carbonated hydroxyapatites (HA) were prepared by precipitation method. Ca-deficient HA samples were obtained by this method with the characteristic hexagonal apatite structure. Scanning transmission electron microscopy (STEM) of two HA samples with two different Mn content has shown that their morphology depends on their Mn content. In case of relatively low (0.73%) Mn content (HAMn1), platelet crystals about micron size and needle-like crystals up to 100 nm were observed, while with 1.23% Mn (HAMn2) crystals were smaller, needle-like and with sizes up to 400 nm only. Mn-doped TCP samples were prepared by two methods. In one case it was obtained by direct solid-state reaction with the characteristic rhombohedral structure of beta-TCP and with composition of Ca(2.7)Mn(0.3)(PO(4))(2). TEM pictures of crystals of this sample were tens of micron and submicron size with visible faces. Crystals of beta-TCP obtained by high temperature partial transformation of sample HAMn2 to beta-TCP were found by TEM to be smaller, micron sized, drop-like shaped, sensitive to beam radiation. These results indicate that the morphology of Mn doped beta-tricalcium phosphate samples depends on the method of their preparation. Morphological properties of HA and TCP are discussed and it is suggested that the smaller and less perfect HA crystals with the higher Mn-content as well as the less perfect TCP crystals obtained by transformation of HA to TCP might be of more biocompatible character.

  5. Calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine: a previously unreported cause of neck pain.

    Science.gov (United States)

    Urrutia, Julio; Contreras, Oscar

    2017-05-01

    Calcific tendinitis is a frequent disorder caused by hydroxyapatite crystal deposition; however, bone erosions from calcific tendinitis are unusual. The spinal manifestation of this disease is calcific tendinitis of the longus colli muscle; this disease has never been described in the posterior aspect of the spine. We report a case of calcium hydroxyapatite crystal deposition involving the posterior cervical spine eroding the bone cortex. A 57-year-old woman presented with a 5-month history of left-sided neck pain. Radiographs showed C4-C5 interspinous calcification with lytic compromise of the posterior arch of C4. Magnetic resonance imaging confirmed a lytic lesion of the posterior arch of C4, with a soft tissue mass extending to the C4-C5 interspinous space; calcifications were observed as very low signal intensity areas on T1 and T2 sequences, surrounded by gadolinium-enhanced soft tissues. A computed tomography (CT) scan confirmed the bone erosions and the soft tissue calcifications. A CT-guided needle biopsy was performed; it showed vascularized connective tissue with inflammatory histiocytic infiltration and multinucleated giant cells; Alizarin Red stain confirmed the presence of hydroxyapatite crystals. The patient was treated with anti-inflammatories for 2 weeks. She has been asymptomatic in a 6-month follow-up; a CT scan at the last follow-up revealed reparative remodeling of bone erosions. This is the first report of calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine. Considering that this unusual lesion can be misinterpreted as a tumor or infection, high suspicion is required to avoid unnecessary surgical procedures.

  6. Sinus Floor Augmentation Comparing an In Situ Hardening Biphasic Calcium Phosphate (Hydroxyapatite/β-Tricalcium Phosphate) Bone Graft Substitute with a Particulate Biphasic Calcium Phosphate (Hydroxyapatite/β-Tricalcium Phosphate) Bone Graft Substitute: An Experimental Study in Sheep.

    Science.gov (United States)

    Wildburger, Angelika; Bubalo, Vladimir; Magyar, Marton; Nagursky, Heiner; Jakse, Norbert; Schmelzeisen, Rainer; Sauerbier, Sebastian

    2017-07-01

    The aim of the present split-mouth study in sheep was to assess the influence of in situ hardening properties of a biphasic calcium phosphate (BCP) bone graft substitute (BGS) (ratio hydroxyapatite/β-tricalcium phosphate = 60/40) compared with a particulate BGS with the same biphasic core-granule composition without in situ hardening properties on sinus floor augmentation. Therefore, bilateral sinus floor augmentation was performed in eight sheep. Poly(lactide-co-glycolide) (PLGA)-coated, in situ hardening biphasic BGS (PLGA-NMP [N-Methyl-2-pyrrolidone]-BCP) was placed at the test site, and a particulate biphasic BGS without PLGA coating (BCP) was used for the contralateral site as a control. Animals were sacrificed after 21 weeks. Sinus augmentation sites were analyzed histologically. The volume was analyzed by computed tomography. Histomorphometric parameters were assessed for the 12 and 21 weeks' time points. Slopes of new bone formation over time were compared with a linear growth regression model. Bone formation after 12 and 21 weeks of healing was 8.94% (±3.74) and 19.82% (±6.29) for PLGA-NMP-BCP and 7.00% (±2.58) and 14.38% (±4.51) for BCP, respectively. The bone growth rate for PLGA-NMP-BCP was higher than the growth rate for BCP (probability 97.5%). The total fraction of calcified hard tissue (% bone fraction + % biomaterial) was around 46% for both tested biomaterials, 21 weeks after sinus floor augmentation. The in situ hardening BGS (PLGA-NMP-BCP) performed better than the particulate material (BCP) in terms of bone formation rate. The in situ hardening properties of the PLGA-NMP-BCP material mediated by the PLGA coating and NMP solution as plasticizer had no negative influence on the bone formation.

  7. Development and optimisation of atorvastatin calcium loaded self-nanoemulsifying drug delivery system (SNEDDS) for enhancing oral bioavailability: in vitro and in vivo evaluation.

    Science.gov (United States)

    Kassem, Abdulsalam M; Ibrahim, Hany M; Samy, Ahmed M

    2017-05-01

    The objective of this study was to develop and optimise self-nanoemulsifying drug delivery system (SNEDDS) of atorvastatin calcium (ATC) for improving dissolution rate and eventually oral bioavailability. Ternary phase diagrams were constructed on basis of solubility and emulsification studies. The composition of ATC-SNEDDS was optimised using the Box-Behnken optimisation design. Optimised ATC-SNEDDS was characterised for various physicochemical properties. Pharmacokinetic, pharmacodynamic and histological findings were performed in rats. Optimised ATC-SNEDDS resulted in droplets size of 5.66 nm, zeta potential of -19.52 mV, t90 of 5.43 min and completely released ATC within 30 min irrespective of pH of the medium. Area under the curve of optimised ATC-SNEDDS in rats was 2.34-folds higher than ATC suspension. Pharmacodynamic studies revealed significant reduction in serum lipids of rats with fatty liver. Photomicrographs showed improvement in hepatocytes structure. In this study, we confirmed that ATC-SNEDDS would be a promising approach for improving oral bioavailability of ATC.

  8. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Graduate Student, Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States); Hu Yongfeng; Zuin, Lucia [Beamline Scientist, Canadian Light Source, Saskatoon, SK (Canada); Appathurai, Narayana [Beamline Scientist, Synchrotron Radiation Center, Madison, WI (United States); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States)

    2011-03-12

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (< 5 wt.%) of Bioglass (registered) 45S5 was added it behaved as a sintering aid and also enhanced the decomposition of hydroxyapatite to {beta}-tricalcium phosphate. However when 10 wt.% and 25 wt.% Bioglass (registered) 45S5 was used it resulted in the formation of Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} and Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L{sub 2,3}-edge and calcium (Ca) K-edge XANES. Si L{sub 2,3}-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L{sub 2,3}-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and {beta}-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in a silicate matrix indicating that it is more soluble compared to the other compositions.

  9. Anticorrosive effects and in vitro cytocompatibility of calcium silicate/zinc-doped hydroxyapatite composite coatings on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yong, E-mail: xfpang@aliyun.com [College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Honglei [College of Chemistry Environmental Science, Hebei University, Baoding 071000 (China); Qiao, Haixia; Nian, Xiaofeng [College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Zhang, Xuejiao, E-mail: 527238610@qq.com [College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Wang, Wendong; Zhang, Xiaoyun; Chang, Xiaotong [College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Han, Shuguang [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Pang, Xiaofeng [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); International Centre for Materials Physics, Chinese Academy of Science, Shenyang 110015 (China)

    2015-12-01

    Highlights: • We developed a ZnHA/CS-coated Ti implant by using an ED method. • The obtained ZnHA/CS coatings presented a net-like micro-porous. • The ZnHA/CS coating possessed an excellent corrosion protection ability. • The composite coated CP-Ti possesses favourable cytocompatibility. - Abstract: This work elucidated the corrosion resistance and cytocompatibility of electroplated Zn- and Si-containing bioactive calcium silicate/zinc-doped hydroxyapatite (ZnHA/CS) ceramic coatings on commercially pure titanium (CP-Ti). The formation of ZnHA/CS coating was investigated through Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray and inductively coupled plasma analyses. The XRD image showed that the reaction layer was mainly composed of HA and CaSiO{sub 3}. The fabricated ZnHA/CS coatings presented a porous structure and appropriate thickness for possible applications in orthopaedic surgery. Potentiodynamic polarization tests showed that ZnHA/CS coatings exhibited higher corrosion resistance than CP-Ti. Dissolution tests on the coating also revealed that Si{sup 4+} and Zn{sup 2+} were leached at low levels. Moreover, MC3T3-E1 cells cultured on ZnHA/CS featured improved cell morphology, adhesion, spreading, proliferation and expression of alkaline phosphatase than those cultured on HA. The high cytocompatibility of ZnHA/CS could be mainly attributed to the combination of micro-porous surface effects and ion release (Zn{sup 2+} and Si{sup 4+}). All these results indicate that ZnHA/CS composite-coated CP-Ti may be a potential material for orthopaedic applications.

  10. Analysis and optimisation of calcium content in menus and dairy offer in Croatian kindergartens

    Directory of Open Access Journals (Sweden)

    Ivana Rumora

    2009-09-01

    Full Text Available The importance of healthy diet from the earliest age as well as its influence on human health is indisputable. Unbalanced diet in childhood can, along with unhealthy lifestyle (stress, smoking, physical inactivity, cause a number of diseases at a later age. Two week menus in 26 kindergartens from continental and coastal Croatia have been analysed, taking into consideration the type of kindergarten (public, private, or religious. The aim of this research is to determine the quality of the offer regarding the intake of milk and dairy products, which, regarding their bioavailability, represent a major source of calcium, an essential nutrient in the intensive growth phase of children and young people. Using basic statistics, significant differences were not determined neither in the regional offer of milk and dairy products in the different types of kindergartens nor in the content of calcium and phosphorus. Milk and dairy products were adequately represented in the weekly offer in both regions under observation, and the average offer contained 9.7±1.5 servings. Average content of calcium in daily menues is 714.5±235.9 mg, which is in agreement with dietary reference intake recommendations (300-800 mg and Croatian recommendations (400-700 mg. Use of fuzzy logic in creating new daily menus, by combining the existing offers enabled significant enlargement of the set of nutritionally acceptable menus as well as a greater diversity of meals.

  11. Magnesium substitution in the structure of orthopedic nanoparticles: A comparison between amorphous magnesium phosphates, calcium magnesium phosphates, and hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Nabiyouni, Maryam, E-mail: maryam.nabiyouni@rockets.utoledo.edu [Department of Bioengineering, University of Toledo, Toledo, OH (United States); Ren, Yufu [Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo, Toledo, OH (United States); Department of Surgery (Dentistry), University of Toledo, Toledo, OH (United States)

    2015-07-01

    As biocompatible materials, magnesium phosphates have received a lot of attention for orthopedic applications. During the last decade multiple studies have shown advantages for magnesium phosphate such as lack of cytotoxicity, biocompatibility, strong mechanical properties, and high biodegradability. The present study investigates the role of Mg{sup +2} and Ca{sup +2} ions in the structure of magnesium phosphate and calcium phosphate nanoparticles. To directly compare the effect of Mg{sup +2} and Ca{sup +2} ions on structure of nanoparticles and their biological behavior, three groups of nanoparticles including amorphous magnesium phosphates (AMPs) which release Mg{sup +2}, calcium magnesium phosphates (CMPs) which release Mg{sup +2} and Ca{sup +2}, and hydroxyapatites (HAs) which release Ca{sup +2} were studied. SEM, TEM, XRD, and FTIR were used to evaluate the morphology, crystallinity, and chemical properties of the particles. AMP particles were homogeneous nanospheres, whereas CMPs were combinations of heterogeneous nanorods and nanospheres, and HAs which contained heterogeneous nanosphere particles. Cell compatibility was monitored in all groups to determine the cytotoxicity effect of particles on studied MC3T3-E1 preosteoblasts. AMPs showed significantly higher attachment rate than the HAs after 1 day and both AMPs and CMPs showed significantly higher proliferation rate when compared to HAs after 7 days. Gene expression level of osteoblastic markers ALP, COL I, OCN, OPN, RUNX2 were monitored and they were normalized to GAPDH housekeeping gene. Beta actin expression level was monitored as the second housekeeping gene to confirm the accuracy of results. In general, AMPs and CMPs showed higher expression level of osteoblastic genes after 7 days which can further confirm the stimulating role of Mg{sup +}2 and Ca{sup +2} ions in increasing the proliferation rate, differentiation, and mineralization of MC3T3-E1 preosteoblasts. - Highlights: • Role of Mg{sup 2

  12. Comparative evaluation of Nano-Hydroxyapatite preparation and Calcium Sucrose Phosphate on microhardness of deciduous teeth after iron drop exposure - An in-vitro study.

    Science.gov (United States)

    Rathi, Nilesh; Baid, Rutika; Baliga, Sudhindra; Thosar, Nilima

    2017-04-01

    To evaluate and compare the microhardness of deciduous teeth treated with nano-hydroxyapatite and calcium sucrose phosphate after iron drop exposure. Twenty healthy anterior deciduous teeth were collected and stored in 0.9% saline solution at room temperature. All the teeth were immersed in artificial saliva in an incubator shaker at 37° for an hour and then subjected to Vickers microhardness test at 100g load for 5 seconds. The teeth were then immersed in iron drop for 5 minutes, twice daily, rinsed with distilled water and kept in artificial saliva. This procedure was repeated for 7 days and teeth were subjected to microhardness testing. Further, the teeth were divided in two groups, each group containing 10 teeth. In group I, nanohydroxyapatite preparation and in group II, calcium sucrose phosphate were applied for 10 minutes, twice daily for 7 days and subjected again to microhardness testing again. Vickers microhardness analysis revealed that iron drop exposure to teeth caused significant decrease in microhardness (pcalcium sucrose phosphate in Group II showed significantly increased enamel microhardness (200.89) than that after iron drop exposure. Statistical difference was seen between the two groups, with nanohydroxyapatite preparation showing increased microhardness than calcium sucrose phosphate. Nanohydroxyapatite preparation and calcium sucrose phosphate have remineralizing effect over teeth affected by acid challenge of iron drops, nanohydroxyapatite preparation showing better results than calcium sucrose phosphate. Key words:Iron drops, Nanohydroxyapaptite, calcium sucrose phosphate, anticay.

  13. Preparation of hydroxyapatite/collagen injectable bone paste with an anti-washout property utilizing sodium alginate. Part 1: influences of excess supplementation of calcium compounds.

    Science.gov (United States)

    Sato, Taira; Kikuchi, Masanori; Aizawa, Mamoru

    2017-03-01

    The anti-washout property, viscosity, and cytocompatibility to an osteoblastic cell line, MG-63, of anti-washout pastes were investigated. Mixing a hydroxyapatite/collagen bone-like nanocomposite (HAp/Col), an aqueous solution of sodium alginate (Na-Alg), which is a paste hardening and lubricant agent, and supplementation of calcium carbonate or calcium citrate (Ca-Cit) as a calcium resource for the hardening reaction realized an injectable bone paste. Adding Ca-Cit at a concentration greater than eight times the Ca(2+) ion concentration to Na-Alg improved the anti-washout property. Although the viscosity test indicated a gradual increase in the paste viscosity as the calcium compounds increased, pastes with excess supplementation of calcium compounds exhibited injectability through a syringe with a 1.8 mm inner diameter, realizing an injectable bone filler. Furthermore, the anti-washout pastes with Ca-Cit had almost the same cell proliferation rate as that of the HAp/Col dense body. Therefore, HAp/Col injectable anti-washout pastes composed of the HAp/Col, Na-Alg, and Ca-Cit are potential candidates for bioresorbable bone filler pastes.

  14. Acute and 3-month effects of microcrystalline hydroxyapatite, calcium citrate and calcium carbonate on serum calcium and markers of bone turnover: a randomised controlled trial in postmenopausal women.

    Science.gov (United States)

    Bristow, Sarah M; Gamble, Greg D; Stewart, Angela; Horne, Lauren; House, Meaghan E; Aati, Opetaia; Mihov, Borislav; Horne, Anne M; Reid, Ian R

    2014-11-28

    Ca supplements are used for bone health; however, they have been associated with increased cardiovascular risk, which may relate to their acute effects on serum Ca concentrations. Microcrystalline hydroxyapatite (MCH) could affect serum Ca concentrations less than conventional Ca supplements, but its effects on bone turnover are unclear. In the present study, we compared the acute and 3-month effects of MCH with conventional Ca supplements on concentrations of serum Ca, phosphate, parathyroid hormone and bone turnover markers. We randomised 100 women (mean age 71 years) to 1 g/d of Ca as citrate or carbonate (citrate-carbonate), one of two MCH preparations, or a placebo. Blood was sampled for 8 h after the first dose, and after 3 months of daily supplementation. To determine whether the acute effects changed over time, eight participants assigned to the citrate dose repeated 8 h of blood sampling at 3 months. There were no differences between the citrate and carbonate groups, or between the two MCH groups, so their results were pooled. The citrate-carbonate dose increased ionised and total Ca concentrations for up to 8 h, and this was not diminished after 3 months. MCH increased ionised Ca concentrations less than the citrate-carbonate dose; however, it raised the concentrations of phosphate and the Ca-phosphate product. The citrate-carbonate and MCH doses produced comparable decreases in bone resorption (measured as serum C-telopeptide (CTX)) over 8 h and bone turnover (CTX and procollagen type-I N-terminal propeptide) at 3 months. These findings suggest that Ca preparations, in general, produce repeated sustained increases in serum Ca concentrations after ingestion of each dose and that Ca supplements with smaller effects on serum Ca concentrations may have equivalent efficacy in suppressing bone turnover.

  15. A study of the formation of amorphous calcium phosphate and hydroxyapatite on melt quenched Bioglass using surface sensitive shallow angle X-ray diffraction.

    Science.gov (United States)

    Martin, R A; Twyman, H; Qiu, D; Knowles, J C; Newport, R J

    2009-04-01

    Melt quenched silicate glasses containing calcium, phosphorous and alkali metals have the ability to promote bone regeneration and to fuse to living bone. These glasses, including 45S5 Bioglass((R)) [(CaO)(26.9)(Na(2)O)(24.4)(SiO(2))(46.1)(P(2)O(5))(2.6)], are routinely used as clinical implants. Consequently there have been numerous studies on the structure of these glasses using conventional diffraction techniques. These studies have provided important information on the atomic structure of Bioglass((R)) but are of course intrinsically limited in the sense that they probe the bulk material and cannot be as sensitive to thin layers of near-surface dissolution/growth. The present study therefore uses surface sensitive shallow angle X-ray diffraction to study the formation of amorphous calcium phosphate and hydroxyapatite on Bioglass((R)) samples, pre-reacted in simulated body fluid (SBF). Unreacted Bioglass((R)) is dominated by a broad amorphous feature around 2.2 A(-1) which is characteristic of sodium calcium silicate glass. After reacting Bioglass((R)) in SBF a second broad amorphous feature evolves ~1.6 A(-1) which is attributed to amorphous calcium phosphate. This feature is evident for samples after only 4 h reacting in SBF and by 8 h the amorphous feature becomes comparable in magnitude to the background signal of the bulk Bioglass((R)). Bragg peaks characteristic of hydroxyapatite form after 1-3 days of reacting in SBF.

  16. The effects of hydroxyapatite/calcium phosphate glass scaffold and its surface modification with bovine serum albumin on 1-wall intrabony defects of beagle dogs: a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Um, Yoo-Jung; Jung, Ui-Won; Chae, Gyung-Joon; Kim, Chang-Sung; Cho, Kyoo-Sung; Kim, Chong-Kwan; Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752 l (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of)], E-mail: shchoi726@yuhs.ac

    2008-12-15

    The purpose of this study was to evaluate the effects of biphasic hydroxyapatite/calcium phosphate glass (HA/CPG) scaffold and its surface modification with bovine serum albumin (BSA) on periodontal regeneration. 1-wall intrabony defects were surgically created on five beagle dogs. HA/CPG scaffolds, with a hydroxyapatite (HA)/calcium phosphate glass (CPG) ratio of 95:5 by weight (%) and surface modification done by 2% bovine serum albumin, were used. The control group received surgical flap operation, and the experimental groups were filled with HA/CPG scaffolds and HA/CPG(BSA) scaffolds. The animals were sacrificed eight weeks after surgery. Histological findings revealed better space maintenance in the experimental groups than the control group, and showed new bone formation intermittently in between the residual material particles. The newly formed bone was mostly woven bone and the residual particles were undergoing resorption. Cementum regeneration was observed with limited root resorption in all the groups. Histometric analysis also revealed greater mean values in new bone formation, cementum regeneration and bone area than the control group in both experimental groups. However, similar findings were presented between HA/CPG and HA/CPG(BSA). The result of the present study revealed the newly fabricated HA/CPG scaffold to have a potential use as a bone substitute material.

  17. Comparative evaluation of Nano-Hydroxyapatite preparation and Calcium Sucrose Phosphate on microhardness of deciduous teeth after iron drop exposure - An in-vitro study

    Science.gov (United States)

    Baid, Rutika; Baliga, Sudhindra; Thosar, Nilima

    2017-01-01

    Background To evaluate and compare the microhardness of deciduous teeth treated with nano-hydroxyapatite and calcium sucrose phosphate after iron drop exposure. Material and Methods Twenty healthy anterior deciduous teeth were collected and stored in 0.9% saline solution at room temperature. All the teeth were immersed in artificial saliva in an incubator shaker at 37° for an hour and then subjected to Vickers microhardness test at 100g load for 5 seconds. The teeth were then immersed in iron drop for 5 minutes, twice daily, rinsed with distilled water and kept in artificial saliva. This procedure was repeated for 7 days and teeth were subjected to microhardness testing. Further, the teeth were divided in two groups, each group containing 10 teeth. In group I, nanohydroxyapatite preparation and in group II, calcium sucrose phosphate were applied for 10 minutes, twice daily for 7 days and subjected again to microhardness testing again. Results Vickers microhardness analysis revealed that iron drop exposure to teeth caused significant decrease in microhardness (pmicrohardness (206.90) than that after iron drop exposure. Similarly, application of calcium sucrose phosphate in Group II showed significantly increased enamel microhardness (200.89) than that after iron drop exposure. Statistical difference was seen between the two groups, with nanohydroxyapatite preparation showing increased microhardness than calcium sucrose phosphate. Conclusions Nanohydroxyapatite preparation and calcium sucrose phosphate have remineralizing effect over teeth affected by acid challenge of iron drops, nanohydroxyapatite preparation showing better results than calcium sucrose phosphate. Key words:Iron drops, Nanohydroxyapaptite, calcium sucrose phosphate, anticay. PMID:28469827

  18. Effect of home-bleaching gels modified by calcium and/or fluoride and the application of nano-hydroxyapatite paste on in vitro enamel erosion susceptibility.

    Science.gov (United States)

    Santos, Luciana Floriani Thives Freitas; Torres, Carlos Rocha Gomes; Caneppele, Taciana Marco Ferraz; Magalhães, Ana Carolina; Borges, Alessandra Buhler

    2016-01-01

    This in vitro study compared the effect of bleaching agents modified by the addition of calcium and/or fluoride and the application of a nano-hydroxyapatite paste after bleaching, on the susceptibility of enamel to erosion. Bovine enamel cylindrical samples (3 mm diameter) were assigned to six groups (n = 20 specimens/group) according to the bleaching agent: no bleaching (C-control), 7.5% hydrogen peroxide gel (HP), HP with 0.5% calcium gluconate (HP+Ca), HP with 0.2% sodium fluoride (HP+F), HP with calcium and fluoride (HP+Ca+F) and HP followed by the application of a nano-hydroxyapatite agent (HP+NanoP). The gels were applied on the enamel surface (1 h) followed by cyclic erosive challenges (Sprite Zero®-2 min), for 14 days. The paste was applied after bleaching for 5 min (HP+NanoP). The enamel surface alteration was measured by contact profilometry (µm) (after 7 and 14 days). C-control (mean ± SD: 2.29 ± 0.37 at 7 days/4.86 ± 0.72 at 14 days) showed significantly lower loss compared to the experimental groups. HP+Ca (3.34 ± 0.37/6.75 ± 1.09) and HP+F (4.49 ± 0.92/7.61 ± 0.90) presented significantly lower enamel loss than HP (4.18 ± 0.50/10.30 ± 1.58) only for 14 days and HP+Ca+F (4.92 ± 1.03/8.12 ± 1.52) showed values similar to the HP+F group. The HP+NanoP (5.51 ± 1.04/9.61 ± 1.21) resulted in enamel loss similar to the HP after 14 days. It was found that 7.5% hydrogen peroxide increased the susceptibility of enamel to erosion. The addition of calcium or fluoride to the bleaching gel reduced the erosion effect, while the nano-hydroxyapatite agent did not provide any protective effect.

  19. Enhancement of nano-hydroxyapatite bonding to dentin through a collagen/calcium dual-affinitive peptide for dentinal tubule occlusion.

    Science.gov (United States)

    Wang, Ronghan; Wang, Qiong; Wang, Xiumei; Tian, Lili; Liu, Huiying; Zhao, Miaomiao; Peng, Ce; Cai, Qiang; Shi, Yunming

    2014-08-01

    Calcium phosphate crystals, as the main component of dentin and enamel, have been widely used for the occlusion of dentinal tubules. However, the low bond strength and poor sealing effect limit their clinical practicality. In this study, a collagen/calcium dual-affinitive peptide E8DS (EEEEEEEEDSpESpSpEEDR) and nano-hydroxyapatite (nano-HAp) flocculi were developed to seal dentin tubules for reducing dentin hypersensitivity, whereas the E8DS peptides were pre-applied to improve the adhesion of occlusive hydroxyapatite coating on dentin collagen matrix for the long-lasting sealing effect and relief from hypersensitivity. Our study showed that E8DS peptides had a strong affinity with dentin collageneous matrix that almost 43.7% of initial E8DS peptides immobilized on exposed dentin samples remained detained after continuous washing by distilled water for four weeks at a rate of 1 mL/min. Nano-HAp flocculi were obtained by re-neutralization of HAp-HCl solution and then brushed onto the surfaces of pre-treated human dentin disks with E8DS peptides, which showed a perfect occlusion of exposed dentinal tubules, as compared with Nano-HAp only and a commercial desensitizer, Green Or. With only around 10-min E8DS peptide pre-treatment, the occlusive mineral layers remained intact against consecutively stirred washing in phosphate-buffered saline or coke for 15 min, and 6 min of tooth-brushing, which implied that our E8DS peptide could comparatively improve the durability of sealant-dentin interface bonds for long-lasting dentine desensitization. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  20. Effect of hydroxyapatite, octacalcium phosphate and calcium phosphate on the auto-flocculation of the microalgae in a high-rate algal pond.

    Science.gov (United States)

    Baya, D T; Effebi, K R; Tangou, T T; Keffala, C; Vasel, J L

    2013-01-01

    Recovering microalgae is one of the main technological and economic concerns in a high-rate algal pond (HRAP) because of their small size and their low density. This paper emphasizes the characterization (identification and assessment of potential flocculation) of chemical compounds involved in microalgae auto-flocculation in a HRAP. First, thermodynamic simulations were performed, using two models (i.e. Visual Minteq and a simplified thermodynamic model) in order to determine the chemical compounds of interest. Experimental tests were then carried out with these compounds for assessing their flocculation ability. Both models revealed that precipitates of calcium phosphates and their substituted forms were the compounds involved in the auto-flocculation. Moreover, experimental tests showed that the stoichiometric neutralization of algal charges by calcium phosphates (i.e. hydroxyapatite (Ca5(PO4)3OH), octacalcium phosphate (Ca4H(PO4)3) and amorphous calcium phosphate (Ca3(PO4)2)), at a pH within the range 7-10 yields 70-82% recovered algal biomass. The optimum ratio required for algae auto-flocculation was 0.33 Ca5(PO4)3OH/g DM(algae) at pH 10, 0.11 Ca4H(PO4)3/g DM(algae) at pH 7 and 0.23 g Ca3(PO4)2/g DM(algae) at pH 9. Auto-flocculation appears as a simple, sustainable and promising method for efficient harvesting of microalgae in a HRAP.

  1. Pulpal response to nano hydroxyapatite, mineral trioxide aggregate and calcium hydroxide when used as a direct pulp capping agent: an in vivo study.

    Science.gov (United States)

    Swarup, S J; Rao, A; Boaz, K; Srikant, N; Shenoy, R

    2014-01-01

    Nano hydroxyapatite (Nano-HA) and Mineral Trioxide Aggregate (MTA) because of its better qualities can be used as an alternative to calcium hydroxide in direct pulp capping procedures. The aim of the study was to compare the response of exposed human pulp to Nano-HA, Mineral Trioxide Aggregate and calcium hydroxide. The study was done on 30 premolars, ranging from patients between 11-15 years. Intentional pulp capping was done using one of the experimental materials. The extracted teeth were then subjected to staining procedure and evaluated for dentin bridge and pulpal response after 15 and 30 days. Intragroup comparisons of the observed values were analyzed using Chi-square test. Nano-HA and MTA produced continuous dentin bridges. Dentin bridge that was formed in MTA group had regular pattern of dentinal tubules but no tubules were seen in the nano-HA group. Dentin bridge was not observed in Dycal group for the 15 days period in majority of the sample and by 30 days dentin bridge was observed that were both continuous and interrupted in equal number of samples. The initial inflammatory response and necrosis was more with Nano-HA and calcium hydroxide which reduced with time. MTA showed no inflammatory changes in majority of the samples in both the study periods. Necrosis was least observed in MTA group followed by Nano-HA. Vascularity increased in Nano-HA group in the initial periods which reduced with increasing time. Based on the ability of nano-HA to produce complete dentinal bridges, favorable cellular and vascular response, the material could be considered as an substitute and could be tried used as a direct pulp capping agent.

  2. Enhanced osteoconductivity of sodium-substituted hydroxyapatite by system instability.

    Science.gov (United States)

    Sang Cho, Jung; Um, Seung-Hoon; Su Yoo, Dong; Chung, Yong-Chae; Hye Chung, Shin; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2014-07-01

    The effect of substituting sodium for calcium on enhanced osteoconductivity of hydroxyapatite was newly investigated. Sodium-substituted hydroxyapatite was synthesized by reacting calcium hydroxide and phosphoric acid with sodium nitrate followed by sintering. As a control, pure hydroxyapatite was prepared under identical conditions, but without the addition of sodium nitrate. Substitution of calcium with sodium in hydroxyapatite produced the structural vacancies for carbonate ion from phosphate site and hydrogen ion from hydroxide site of hydroxyapatite after sintering. The total system energy of sodium-substituted hydroxyapatite with structural defects calculated by ab initio methods based on quantum mechanics was much higher than that of hydroxyapatite, suggesting that the sodium-substituted hydroxyapatite was energetically less stable compared with hydroxyapatite. Indeed, sodium-substituted hydroxyapatite exhibited higher dissolution behavior of constituent elements of hydroxyapatite in simulated body fluid (SBF) and Tris-buffered deionized water compared with hydroxyapatite, which directly affected low-crystalline hydroxyl-carbonate apatite forming capacity by increasing the degree of apatite supersaturation in SBF. Actually, sodium-substituted hydroxyapatite exhibited markedly improved low-crystalline hydroxyl-carbonate apatite forming capacity in SBF and noticeably higher osteoconductivity 4 weeks after implantation in calvarial defects of New Zealand white rabbits compared with hydroxyapatite. In addition, there were no statistically significant differences between hydroxyapatite and sodium-substituted hydroxyapatite on cytotoxicity as determined by BCA assay. Taken together, these results indicate that sodium-substituted hydroxyapatite with structural defects has promising potential for use as a bone grafting material due to its enhanced osteoconductivity compared with hydroxyapatite. © 2013 Wiley Periodicals, Inc.

  3. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Radwan, M.M., E-mail: mmahmoudradwan@yahoo.com [Ceramics Dept, National Research Centre, Cairo (Egypt); Abd El-Hamid, H.K. [Ceramics Dept, National Research Centre, Cairo (Egypt); Mohamed, A.F. [The Holding Company for Production of Vaccines, Sera and Drugs (EGYVAC) (Egypt)

    2015-12-01

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C{sub 2}S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C{sub 2}S (27–30 nm) was prepared by solid state reaction at 1450 °C, while biphasic compound TCP/HAp (7–15 nm) was synthesized from an aqueous solution of Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}·12H{sub 2}O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C{sub 2}S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way. - Highlights: • The dissolution and hydration of β-C{sub 2}S and TCP/HAp in distilled water and saline solution were studied. • TCP/HAp did not show mechanical strength, while β-C{sub 2}S showed good mechanical strength. • The use of saline solution did enhances the dissolution & hydration rate. • An increase in pH values was detected when using saline solution. • Both materials showed a moderate cytotoxicity in no significant way.

  4. The usability of ark clam shell (Anadara granosa) as calcium precursor to produce hydroxyapatite nanoparticle via wet chemical precipitate method in various sintering temperature.

    Science.gov (United States)

    Khiri, Mohammad Zulhasif Ahmad; Matori, Khamirul Amin; Zainuddin, Norhazlin; Abdullah, Che Azurahanim Che; Alassan, Zarifah Nadakkavil; Baharuddin, Nur Fadilah; Zaid, Mohd Hafiz Mohd

    2016-01-01

    This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35-69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries .

  5. Light scattering study on the size and structure of calcium phosphate/hydroxyapatite flocs formed in sugar solutions.

    Science.gov (United States)

    Greenwood, Judy; Rainey, Tom; Doherty, William O S

    2007-02-01

    The formation, flocculation and sedimentation of calcium phosphate particles are among the main physico-chemical reactions that occur during the clarification of cane sugar juice. The mechanisms through which processes occur in juice clarification are still poorly understood. This study (being part of a comprehensive investigation to unravel these mechanisms) reports on the size and structure of calcium phosphate particles and aggregates in water and sugar solutions at 20 degrees C using the small angle laser light scattering technique. The average size of the primary calcium phosphate particles was in the range 10.4+/-1.1 microm to 17.5+/-1.2 microm and the scattering exponents, which describe the structure of the calcium phosphate flocs, varied from 1.97 to 2.76. The flocs formed without flocculant are more compact in water than those formed in sugar solution. The compactness of the flocs was also affected by pH of the solution. This effect has been explained by considering the electrical double layer phenomenon.

  6. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  7. Mechanical and physical behavior of newly developed functionally graded materials and composites of stainless steel 316L with calcium silicate and hydroxyapatite.

    Science.gov (United States)

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Mehrali, Mehdi; Yau, Yat Huang; Tarlochan, Faris; Abu Osman, Noor Azuan

    2015-09-01

    This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Histological evaluation of tissue reactions to newly synthetized calcium silicate- and hydroxyapatite-based bioactive materials: in vivo study

    Directory of Open Access Journals (Sweden)

    Opačić-Galić Vanja

    2017-01-01

    Full Text Available Introduction/Objective. Development of materials which could be used as biological bone substitutes is one of the most valuable and active fields of biomaterial research. The goal of the study was to research the reaction of tissue on calcium silicate- (CS and hydroxyapatitebased (CS-HA newly synthesized nanomaterials, after being implanted into the subcutaneous tissue of a rats and direct pulp capping of rabbit teeth. Methods. The tested materials were implanted in 40 Wistar male rats, sacrificed after seven, 15, 30, and 60 days. The direct pulp capping was performed on the teeth of rabbits. Cavities were prepared on the vestibular surface of the incisors. The animals were sacrificed after 10 and 15 days. The control material was mineral trioxide aggregate (MTA. Histological analysis covered the tracking of inflammatory reaction cellular components, presence of gigantic cells, and necrosis of the tissue. Results. Seven days after the implantation, the strongest inflammatory response was given by the MTA (3.3 Ѓ} 0.48, while CS and CS-HA scored 3 ± 0.71. After 60 days, the rate of inflammatory reactions dropped, which was the least visible with CS-HA (0.2 ± 0.45. The least visible inflammatory reaction of the rabbits’ pulp tissue was spotted with the CS (1.83 ± 0.75, than with the MTA and CS-HA (2.67 ± 1.53, 3 ± 0.63. Conclusion. The newly synthesized materials caused a slight reaction of the subcutaneous tissue. CS-HA showed the best tissue tolerance. Nanostructural biomaterials caused a slight to moderate inflammatory reaction of the rabbits’ pulp tissue only in the immediate vicinity of the implanted material.

  10. Shynthesis and Characterizations of Calcium Hydroxyapatite Derived from Crabs Shells (Portunus pelagicus and Its Potency in Safeguard against to Dental Demineralizations

    Directory of Open Access Journals (Sweden)

    Indah Raya

    2015-01-01

    Full Text Available Crab’s shells of Portunus pelagicus species were used as raw materials for synthesis of hydroxyapatite were used for protection against demineralization of teeth. Calcination was conducted to crab’s shells of Portunus pelagicus at temperature of 1000°C for 5 hours. The results of calcination was reacted with (NH42HPO4, then dried at 110°C for 5 hours. Sintering was conducted to results of precipitated dried with temperature variations 400–1000°C for a hour each variation of temperature then characterized by X-ray diffractometer and FTIR in order to obtain the optimum formation temperature of hydroxyapatite is 800°C. The hydroxyapatite is then tested its effectiveness in protection against tooth demineralization using acetate buffer pH 5.0 with 1 M acetic acid concentration with the addition of hydroxyapatite and time variation of immersion. The results showed that the rate of tooth demineralization in acetate buffer decreased significantly with the provision of hydroxyapatite into a solution where the addition of the magnitude of hydroxyapatite is greater decrease in the rate of tooth demineralization.

  11. Monoclinic hydroxyapatite.

    Science.gov (United States)

    Elliott, J C; Mackie, P E; Young, R A

    1973-06-08

    The existence of a monoclinic phase of hydroxyapatite, Ca(2)(PO(4))(4)OH, has been confirmed, by single-crystal structure analysis (weighted "reliability" factor = 3.9 percent on |F|(2)). The structure has space group P21/b, a = 9.4214(8) angstroms, b = 2a, c = 6.8814(7) angstroms, and gamma = 120 degrees , and is analogous to that of chlorapatite. The distortions from the hexagonal structure with which the monoclinic structure is pseudosymmetric are similar to those in chlorapatite, including enlargement of that triangular array of oxygen atoms in which the chlorine ion or, in hydroxyapatite, the hydroxyl hydrogen ion is approximately centered. The hydroxyapatite specimen was prepared by the conversion of a single crystal of chlorapatite in steam at 1200 degrees C, was mimetically twinned, and was approximately 37 percent monoclinic.

  12. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  13. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  14. Hydroxyapatite-coated uncemented implants and peri-implant infection

    NARCIS (Netherlands)

    Oosterbos, Cornelis Johannes Maria

    2004-01-01

    One of the major complications of joint replacement surgery is a peri-implant infection. A hip prosthesis coated with hydroxyapatite, a calcium phosphate (found in human bone), may offer protection in this respect. In a series of patients who were treated with a hydroxyapatite-coated hip prosthesis

  15. In vitro corrosion investigations of plasma-sprayed hydroxyapatite ...

    Indian Academy of Sciences (India)

    The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer's solution).

  16. Development of hydroxyapatite bone cement for controlled drug ...

    Indian Academy of Sciences (India)

    The purpose of this work was to study the preparation and characterization of drug–hydroxyapatite cement. The hydroxyapatite (HA) cement has been synthesized by using tricalcium phosphate, calcium carbonate and dicalcium phosphate anhydrous with sodium hydrogen phosphate as liquid phase. The effect of added ...

  17. In vitro corrosion investigations of plasma-sprayed hydroxyapatite ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate. (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer's solution).

  18. Effect of biopolymers on structure of hydroxyapatite and interfacial interactions in biomimetically synthesized hydroxyapatite/biopolymer nanocomposites.

    Science.gov (United States)

    Verma, Devendra; Katti, Kalpana S; Katti, Dinesh R

    2008-06-01

    The interfacial interaction and effect of biopolymer on crystal structure of hydroxyapatite in biomimetically synthesized nanocomposites, chitosan/hydroxyapatite (ChiHAP50), polygalacturonic acid/hydroxyapatite (PgAHAP50), and chitosan/polygalacturonic acid/hydroxyapatite (ChiPgAHAP50) have been investigated using atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and Rietveld analysis. AFM phase images show nano-sized hydroxyapatite particles uniformly distributed in biopolymer. FTIR spectra indicate that chitosan interacts with hydroxyapatite through NH(3)(+) groups, whereas in polygalacturonic acid/hydroxyapatite, dissociated carboxylate groups (COO(-)) form unidentate chelate with calcium atoms. A change in lattice parameters of hydroxyapatite in all nanocomposites is observed using Rietveld analysis. The increase in lattice parameters was most prominent along c-axis in ChiHAP50 and ChiPgAHAP50 nanocomposites, which was 0.388% and 0.319%, respectively. Comparison between particle sizes of hydroxyapatite, determined from AFM and Rietveld analysis, indicates presence of amorphous phase in hydroxyapatite particles, which is believed to be present at the interface of hydroxyapatite and biopolymer.

  19. Synthesis of nanocrystalline hydroxyapatite by using precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Mobasherpour, I. [Ceramics Department, Materials and Energy Research Center, P.O. Box 31787-316, Tehran (Iran, Islamic Republic of)]. E-mail: I_Mabasherpour@merc.ac.ir; Heshajin, M. Soulati [Biomaterials Engineering Department, Amir Kabir University of Tehran, Tehran (Iran, Islamic Republic of); Kazemzadeh, A. [Ceramics Department, Materials and Energy Research Center, P.O. Box 31787-316, Tehran (Iran, Islamic Republic of); Zakeri, M. [Materials Engineering Department, Islamic Azad University of Saveh, Saveh (Iran, Islamic Republic of)

    2007-03-14

    In this investigation, hydroxyapatite powder has been synthesized from the calcium nitrate hydrated and di-ammonium hydrogen phosphate solution by precipitation method and heat treatment of hydroxyapatite powders. In order to study the structural evolution, the Fourier transform infrared spectroscopy (FTIR), the X-ray diffraction (XRD) and simultaneous thermal analysis (STA) were used. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to estimate the particle size of the powder and observe the morphology and agglomeration state of the powder. Results show that hydroxyapatite nanocrystalline can successfully be produced by precipitation technique from raw materials. Hydroxyapatite grain gradually increased in size when temperature increased from 100 to 1200 {sup o}C, and the hydroxyapatite hexagonal-dipyramidal phase was not transformed to the other calcium phosphates phases up to 1200 {sup o}C.

  20. Optimisation and validation of a high throughput screening compatible assay to identify inhibitors of the plasma membrane calcium ATPase pump--a novel therapeutic target for contraception and malaria.

    Science.gov (United States)

    Mohamed, Tamer M A; Zakeri, Simon A; Baudoin, Florence; Wolf, Markus; Oceandy, Delvac; Cartwright, Elizabeth J; Gul, Sheraz; Neyses, Ludwig

    2013-01-01

    ATPases, which constitute a major category of ion transporters in the human body, have a variety of significant biological and pathological roles. However, the lack of high throughput assays for ATPases has significantly limited drug discovery in this area. We have recently found that the genetic deletion of the ATP dependent calcium pump PMCA4 (plasma membrane calcium/calmodulin dependent ATPase, isoform 4) results in infertility in male mice due to a selective defect in sperm motility. In addition, recent discoveries in humans have indicated that a single nucleotide polymorphism (SNP) in the PMCA4 gene determines the susceptibility towards malaria plasmodium infection. Therefore, there is an urgent need to develop specific PMCA4 inhibitors. In the current study, we aim to optimise and validate a high throughput screening compatible assay using recombinantly expressed PMCA4 and the HTRF® Transcreener® ADP (TR-FRET) assay to screen a drug library. PMCA4 membrane microsomes were prepared from HEK293 cells overexpressing PMCA4. Western blot quantification revealed nearly nine-fold increased expression of PMCA4 compared to LacZ (control virus)-infected cells. Maximal PMCA4 microsomal activity was achieved in the TR-FRET assay with 15ng/μl microsomal concentration, 30-minute pre-incubation with compounds at 37°C, and calcium buffering with 1mM EGTA providing 1μM free-calcium. Finally a dose-response curve for carboxyeosin (a non-specific PMCA inhibitor) under optimised conditions showed significant PMCA4 inhibition. Upon confirmation that the assay was suitable for high-throughput screening, we have screened the ChemBioNet small molecule library (~21,000 compounds) against the PMCA4 assay to identify those that are its apparent inhibitors. This screening yielded 1,494 primary hits. We have optimised the HTRF® Transcreener® ADP assay for high-throughput screening to identify PMCA4 inhibitors. The output of the screening campaign has provided preliminary chemical

  1. Dispersed hydroxyapatite and modified bioglass 45S5 composites: sintering behavior of glass matrix ranging from 20 to 30 wt% in calcium oxide investigation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.C.; Parra-Silva, J.; Santos, S.C.; Mello-Castanho, S.R.H, E-mail: dasilva.ac@uol.com.br [Instituto de Pesquisas Enegeticas e Nucleares (IPEN/CNEN-SP), DP (Brazil); Braga, F.J.C. [Consulmat Materiais de Referencia, Solucoes e Servicos, Sao Carlos, SP (Brazil); Setz, L.F.G. [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2014-07-01

    Biomaterial technology plays an important role in cell-based tissue proliferation environment creation. The hydroxyapatite (HA) bioceramics are reference materials to employment as a bone substitute, however, their slow rate of degradation and its low rate of bioactivity (Ib) are presented as limiting factors for application as bone graft. In contrast, the bioglass (BG) is a resorbable and osteoinductive material and can act as fluxing in HA/BG composites. The present work objective the development of HA/BG (40/70wt%) composites, Three compositions of the 45S5 bioglass derived ranging from 20-30wt% in CaO were used in order to study the sintering behavior of these materials with hydroxyapatite 30wt% dispersed. The composites were uniaxially pressed in the form of cylinders and sinterized at (1100°C/1h). The characterization was made employing scanning electron microscopy, Infra-Red Spectrometry, X-ray diffraction and hydrolytic resistance test. The results indicate the potential use of the materials developed for applications like bone graft.(author)

  2. Cementless Hydroxyapatite Coated Hip Prostheses

    Science.gov (United States)

    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

  3. Cementless Hydroxyapatite Coated Hip Prostheses

    Directory of Open Access Journals (Sweden)

    Antonio Herrera

    2015-01-01

    Full Text Available 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.

  4. Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: bonding to titanium and scanning electron microscopy.

    Science.gov (United States)

    Tredwin, Christopher J; Georgiou, George; Kim, Hae-Won; Knowles, Jonathan C

    2013-05-01

    Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) production has been characterised and optimised by the sol-gel method and the dissolution and biological properties of these materials were investigated. It was the objective of this study to investigate the potential bond strength and interaction of these materials with titanium. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Using a spin coating technique the sol-gels were coated onto commercially pure titanium disks and crystallised at various temperatures. Using scanning electron microscopy (SEM) and elemental analysis, the surface characteristics, coating thickness and interaction of the Ti substrate and coating were investigated. The bond strengths of the coating to the Ti were investigated using an Instron Universal Load Testing Machine. Statistical analysis was performed with a two-way analysis of variance and post hoc testing with a Bonferroni correction. (1) Coating speed inversely influenced the coating thickness. (2) Increasing fluoride ion substitution and heating temperature significantly increased bond strength and (3) increasing fluoride ion substitution increased the coating thickness. FHA and FA synthesised using the sol-gel technique may offer a superior alternative to coating titanium implants with HA and plasma spraying. HA, FHA and FA materials synthesised by the sol-gel method may also have a use as bone grafting materials. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Unusual facet cyst containing struvite and hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Grantham, M.; Richmond, B. [Dept. of Musculoskeletal Radiology, Cleveland Clinic Foundation, OH (United States)

    2001-01-01

    This case report describes a patient with severe back pain and radiculopathy. She was found to have a facet cyst within the lumbar spine that appeared to contain calcium on MRI and CT. Upon aspiration the cyst was found to contain calcium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite). Ammonia production in the presence of urease-producing bacteria is responsible for the production of struvite in the human body. We postulate that there was a prior infection of the facet with urease-producing bacteria, thus accounting for the production of the struvite within the facet cyst. (orig.)

  6. Hydroxyapatite-coated uncemented implants and peri-implant infection

    OpenAIRE

    Oosterbos, Cornelis Johannes Maria

    2004-01-01

    One of the major complications of joint replacement surgery is a peri-implant infection. A hip prosthesis coated with hydroxyapatite, a calcium phosphate (found in human bone), may offer protection in this respect. In a series of patients who were treated with a hydroxyapatite-coated hip prosthesis for their osteoarthritis, excellent clinical performance and radiographic appearance were found after 5 and 10 years. Radiographically there were signs of osseointegration of the proximal part of t...

  7. Fine structure study on low concentration zinc substituted hydroxyapatite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Wei [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Ma, Jun, E-mail: caltary@gmail.com [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, Jianglin [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, Shengmin, E-mail: smzhang@mail.hust.edu.cn [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); China-Korea Center for Biomaterials and Nano-biotechnology, Life Science Building, 1037 Luoyu Road, Wuhan 430074 (China); Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-12-01

    The fine structure of zinc substituted hydroxyapatite was studied using experimental analysis and first-principles calculations. The synthetic hydroxyapatite nanoparticles containing low Zn concentration show rod-like morphology. The crystallite sizes and unit-cell volumes tended to decrease with the increased Zn concentration according to X-ray diffraction patterns. The Zn K-edge X-ray absorption spectra and fitting results suggest that the hydroxyapatite doped with 0.1 mole% zinc is different in the zinc coordination environments compared with that containing more zinc. The density function theory calculations were performed on zinc substituted hydroxyapatite. Two mechanisms included replacing calcium by zinc and inserting zinc along the hydroxyl column and were investigated, and the related substitution energies were calculated separately. It is found that the substitution energies are negative and lowest for inserting zinc between the two oxygen atoms along the hydroxyl column (c-axis). Combined with the spectral analysis, it is suggested that the inserting mechanism is favored for low concentration zinc substituted hydroxyapatite. Highlights: Black-Right-Pointing-Pointer We investigate the fine structure of hydroxyapatite with low content of Zn. Black-Right-Pointing-Pointer XANES spectra are similar but a little different at low zinc content. Black-Right-Pointing-Pointer Zinc ions influence hydroxyapatite crystal formation and lattice parameters. Black-Right-Pointing-Pointer Formation energies are calculated according to plane-wave density function theory. Black-Right-Pointing-Pointer Low content of zinc prefers to locate at hydroxyl column in hydroxyapatite lattice.

  8. Synthesis and characterization of nanostructured powders of hydroxyapatite and of three-calcium {beta} phosphate: elaboration of two phase compositions for application in the orthopedics and traumatology; Sintese e caracterizacao de pos nanoestruturados de hidroxiapatita e de fosfato tricalcico {beta}: elaboracao de composicoes bifasicas para aplicacoes na ortopedia e traumatologia

    Energy Technology Data Exchange (ETDEWEB)

    Dalmonico, G.M.L.; Pinheiro, D.M.; Camargo, N.H.A.; Orzechowki, L.G.; Goncalves, A.F.; Melnik, V.; Jesus, J.; Gemelli, E. [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas], e-mail: gidalmonico@gmail.com

    2010-07-01

    This paper synthesized nano structured hydroxyapatite and three calcium {beta} phosphate, for elaboration of two phase compositions of HA/TCP in the concentration in volume of 80% HA/20% TCP-{beta}, 60% HA/40% TCP-{beta} and 50% HA/50% TCP-{beta}. For phase mixing realization, the method of mechanical fragmentation by attritor mill were used. The material recovered from the process of mechanical fragmentation was dried in rotate evaporator, supplying the two phase compositions. The preliminary studies shown the obtention of nano metric powders and a good phase dispersions inside the two phase compositions. (author)

  9. Evolving application of biomimetic nanostructured hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Norberto Roveri

    2010-11-01

    Full Text Available Norberto Roveri, Michele IafiscoLaboratory of Environmental and Biological Structural Chemistry (LEBSC, Dipartimento di Chimica ‘G. Ciamician’, Alma Mater Studiorum, Università di Bologna, Bologna, ItalyAbstract: By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical–physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical–physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical–physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications.Keywords: hydroxyapatite, nanocrystals, biomimetism, biomaterials, drug delivery, remineralization

  10. Biphasic calcium phosphates (BCP of hydroxyapatite (HA and tricalcium phosphate (TCP as bone substitutes: Importance of physicochemical characterizations in biomaterials studies

    Directory of Open Access Journals (Sweden)

    Mehdi Ebrahimi

    2017-02-01

    Full Text Available The data presented in this article are related to the research article entitled “Biphasic calcium phosphates bioceramics (HA/TCP: Concept, physicochemical properties and the impact of standardization of study protocols in biomaterials research” [1]. This article provides in depth study of BCP bone substitutes as valuable option in the field of tissue engineering. However, there are discrepancies in the literature regarding the ideal physicochemical properties of BCP and the ideal balance between different phase compositions for enhanced bone tissue engineering (M. Ebrahimi, M.G. Botelho, S.V. Dorozhkin, 2016; M. Ebrahimi, P. Pripatnanont, S. Suttapreyasri, N. Monmaturapoj, 2014 [1,2]. This is found to be mainly because of improper characterization of BCP bioceramics in basic studies and lack of standard study protocols in in vitro and in vivo research. This data article along with original article provide the basic data required for ideal characterization of BCP and other bioceramics in an attempt to provide basic standardized protocols for future studies.

  11. The microstructural and in vitro characteristics of hydroxyapatite coating fabricated using Nd-YAG laser

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2015-03-01

    Full Text Available Hydroxyapatite (HAP) is the most researched calcium phosphate material in the field of biomaterials to be used for bone re-engineering applications; given its attractive properties. Plasma spraying is the best available industrial method that can...

  12. Preparation and characterization of selenite substituted hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jun; Wang, Yanhua; Zhou, Lei [Advance Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, Shengmin, E-mail: caltary@gmail.com [Advance Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); China-Korea Center for Biomaterials and Nano-biotechnology, Life Science Building, 1037 Luoyu Road, Wuhan 430074 (China)

    2013-01-01

    Selenite-substituted hydroxyapatite (Se-HA) with different Se/P ratios was synthesized by a co-precipitation method, using sodium selenite (Na{sub 2}SeO{sub 3}) as a Se source. Selenium has been incorporated into the hydroxyapatite lattice by partially replacing phosphate (PO{sub 4}{sup 3-}) groups with selenite (SeO{sub 3}{sup 2-}) groups. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) techniques reveal that substitutions of phosphate groups by selenite groups cause lower carbonate groups occupying at phosphate sites and change the lattice parameters of hydroxyapatite. The powders obtained are nano-crystalline hydroxyapatite when the Se/P ratios are not more than 0.1. The particle shape of Se-HA has not been altered compared with selenite-free hydroxyapatite but Se-incorporation reduces the crystallite size. The crystallinity was reduced as the Se/P ratios increased until amorphous phase (Se/P = 0.3) appeared in the Se-HA powder obtained, and then another crystal phase presented as calcium selenite hydrate (Se/P = 10). In addition, the sintering tests show that the Se-HA powders with the Se/P ratio of 0.1 have thermal stability at 900 Degree-Sign C for 2 h; hence they have great potential in the fabrication of bone repair scaffolds. - Highlights: Black-Right-Pointing-Pointer We investigate the Se/P ratio for the synthesis of selenium substituted HA. Black-Right-Pointing-Pointer Nano-crystalline HA structure is remained when Se/P ratio is below 0.1. Black-Right-Pointing-Pointer Calcium selenite hydrate forms when Se/P ratio is beyond 10. Black-Right-Pointing-Pointer Selenite substituted HA powders (Se/P < 0.1) are stable at 900 Degree-Sign C for 2 h.

  13. Characterization and formation of hydroxyapatite on Ti6Al4V coated by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Durdu, Salih; Deniz, Oemer Faruk; Kutbay, Is Latin-Small-Letter-Dotless-I l [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey); Usta, Metin, E-mail: ustam@gyte.edu.tr [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Ti6Al4V alloys were coated by PEO in calcium acetate and {beta}-calcium glycerophosphate. Black-Right-Pointing-Pointer Hydroxyapatite and calcium apatite based phases were directly formed on Ti6Al4V. Black-Right-Pointing-Pointer Hydroxyapatite coatings were characterized systematically for different times. Black-Right-Pointing-Pointer After 5 min, hydroxyapatite and calcium based phases begin to form on the coating. Black-Right-Pointing-Pointer HAp on the coating is amorphous due to the rapid solidification during PEO. - Abstract: In this study, Ti6Al4V alloy was coated in the solution consisting of calcium acetate (CA) and {beta}-calcium glycerophosphate ({beta}-Ca-GP) by plasma electrolytic oxidation (PEO) to produce hydroxyapatite and calcium apatite-based composite used as of bioactive and biocompatible materials in biomedical applications. The phase structures, surface morphologies, functional groups of molecules, chemical compositions of the surfaces and the binding energies of atoms in the coating were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Anatase, rutile, calcium oxide, titanium phosphide, whitlockite, tri-calcium phosphate (TCP), perovskite calcium titanate and hydroxyapatite phases on the coating were detected by XRD analysis. The surface of coatings produced by PEO method has a porous structure. The amount of amorphous hydroxyapatite is the highest value for the coating produced at 5 min in XPS and ATR-FTIR results, whereas the amount of crystalline hydroxyapatite has the highest value for coating produced at 120 min in XRD results.

  14. Adsorption of benzoxaboroles on hydroxyapatite phases.

    Science.gov (United States)

    Pizzoccaro, Marie-Alix; Nikel, Ondrej; Sene, Saad; Philippe, Coralie; Mutin, P Hubert; Bégu, Sylvie; Vashishth, Deepak; Laurencin, Danielle

    2016-09-01

    calcium phosphates for drug-formulation purposes has not been looked into. Here, we describe the first study of the adsorption of benzoxaboroles on hydroxyapatite, which is the main mineral phase present in bone. We describe the mode of grafting of benzoxaboroles on this material, and show that they only weakly bind to its surface, especially in comparison to other ionic species commonly found in physiological media, such as phosphates and carboxylates. This demonstrates that administered benzoxaborole drugs are unlikely to remain adsorbed on hydroxyapatite surfaces for long periods of time, which means that their biodistribution will not be affected by such phenomena. Moreover, this work shows that the formulation of benzoxaborole drugs by association to calcium phosphates like hydroxyapatite will lead to a rapid release of the molecules. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. The precursors effects on biomimetic hydroxyapatite ceramic powders.

    Science.gov (United States)

    Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

    2017-06-01

    In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Production of zinc substituted hydroxyapatite using various precipitation routes.

    Science.gov (United States)

    Shepherd, David; Best, Serena M

    2013-04-01

    Substituted hydroxyapatites have been investigated for use as bone grafts and have been investigated for many years. Zinc is of interest due to its potential to reduce bone resorption and antibacterial properties. However, it has proven problematic to substitute biologically significant levels of zinc into the crystal structure through wet chemical routes, whilst retaining the high temperature phase stability required for processing. The aim of this study is to investigate two different precipitation routes used to synthesize zinc substituted hydroxyapatite and to explore the effects of ammonia used in the reactions on the levels of zinc substituted into the crystal lattice. It was found that considerable amounts of ammonia are required to maintain a pH sufficiently high for the production of stoichiometric hydroxyapatite using a reaction between calcium nitrate, zinc nitrate and ammonium phosphate. X-ray fluorescence analysis showed that a significant proportion of the zinc added did not substitute into the hydroxyapatite lattice. Fourier transform infrared spectroscopy revealed the existence of a zinc-ammonia complex that, it is proposed, inhibits zinc substitution for calcium. It was found that by reacting orthophosphoric acid with calcium nitrate and zinc nitrate, the volume of ammonia required in the reaction was reduced and higher levels of zinc substitution were achieved, with up to 0.58 wt% incorporated into the hydroxyapatite lattice. The resulting products were found to be stoichiometric hydroxyapatite and did not appear to contain any extraneous calcium phosphate phases after heat treatment up to 1100 °C. X-ray diffraction and Rietveld analysis revealed that the effect of substituting zinc into the HA lattice was to decrease the a-lattice parameter whilst increasing the c-lattice. Transmission electron microscopy also showed that the incorporation of zinc reduced both the length and width of the precipitated crystals.

  17. Synthesis of hydroxyapatite nanopowders by sol–gel emulsion

    Indian Academy of Sciences (India)

    Hydroxyapatite nanopowders were synthesized by a sol–gel emulsion technique by varying the concentration of a non-ionic surfactant in the organic phases (oil phase) of water-in-oil (w/o) emulsion. Calcium acetate dissolved in distilled water and phosphorous pentoxide dissolved in 2-butanol were used as starting ...

  18. Development of hydroxyapatite-based nanomaterials to enhance ...

    African Journals Online (AJOL)

    ... cells in tissue engineering microspheres. The outcome of this study may have a major impact on the development of novel nanomaterials for bone tissue engineering. Keywords: Chitosan/gelatin-hydroxyapatite, Osteoblast, Osteoinduction, Bone tissue engineering, Nanomaterials, Microspheres, Calcium nodule formation ...

  19. Sphingoid bases inhibit acid-induced demineralization of hydroxyapatite

    NARCIS (Netherlands)

    Valentijn-Benz, M.; van 't Hof, W.; Bikker, F.J.; Nazmi, K.; Brand, H.S.; Sotres, J.; Lindh, L.; Arnebrant, T.; Veerman, E.C.I.

    2015-01-01

    Calcium hydroxyapatite (HAp), the main constituent of dental enamel, is inherently susceptible to the etching and dissolving action of acids, resulting in tooth decay such as dental caries and dental erosion. Since the prevalence of erosive wear is gradually increasing, there is urgent need for

  20. Amino acid-assisted synthesis of strontium hydroxyapatite bone ...

    Indian Academy of Sciences (India)

    Strontium was quantitatively incorporated into hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. The strontium substituted bone cement has potential for use in orthopaedic surgeries. The present study shows that the addition of ...

  1. Biomineralization of nanoscale single crystal hydroxyapatite.

    Science.gov (United States)

    Omokanwaye, Tiffany; Wilson, Otto C; Gugssa, Ayelle; Anderson, Winston

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague-Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54nm and 0.23nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. A process for the development of strontium hydroxyapatite

    Science.gov (United States)

    Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

    2014-06-01

    A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results.

  3. Bone regeneration based on nano-hydroxyapatite and hydroxyapatite/chitosan nanocomposites: an in vitro and in vivo comparative study

    Science.gov (United States)

    Tavakol, S.; Nikpour, M. R.; Amani, A.; Soltani, M.; Rabiee, S. M.; Rezayat, S. M.; Chen, P.; Jahanshahi, M.

    2013-01-01

    Surface morphology, surface wettability, and size distribution of biomaterials affect their in vitro and in vivo bone regeneration potential. Since nano-hydroxyapatite has a great chemical and structural similarity to natural bone and dental tissues, incorporated biomaterial of such products could improve bioactivity and bone bonding ability. In this research, nano-hydroxyapatite (23 ± 0.09 nm) and its composites with variety of chitosan content [2, 4, and 6 g (45 ± 0.19, 32 ± 0.12, and 28 ± 0.12 nm, respectively)] were prepared via an in situ hybridization route. Size distribution of the particles, protein adsorption, and calcium deposition of powders by the osteoblast cells, gene expression and percentage of new bone formation area were investigated. The highest degree of bone regeneration potential was observed in nano-hydroxyapatite powder, while the bone regeneration was lowest in nano-hydroxyapatite with 6 g of chitosan. Regarding these data, suitable size distribution next to size distribution of hydroxyapatite in bone, smaller size, higher wettability, lower surface roughness of the nano-hydroxyapatite particles and homogeneity in surface resulted in higher protein adsorption, cell differentiation and percentage of bone formation area. Results obtained from in vivo and in vitro tests confirmed the role of surface morphology, surface wettability, mean size and size distribution of biomaterial besides surface chemistry as a temporary bone substitute.

  4. Bone regeneration based on nano-hydroxyapatite and hydroxyapatite/chitosan nanocomposites: an in vitro and in vivo comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Tavakol, S. [Tehran University of Medical Sciences, Department of Medical Nanotechnology, School of Advanced Technologies in Medicine (Iran, Islamic Republic of); Nikpour, M. R. [Babol University of Technology, Nanotechnology Research Institute, Nanobiotechnology Research Group (Iran, Islamic Republic of); Amani, A. [Tehran University of Medical Sciences, Department of Medical Nanotechnology, School of Advanced Technologies in Medicine (Iran, Islamic Republic of); Soltani, M. [University of Waterloo, Department of Chemical Engineering, Waterloo Institute for Nanotechnology (Canada); Rabiee, S. M. [Babol University of Technology, Nanotechnology Research Institute, Nanobiotechnology Research Group (Iran, Islamic Republic of); Rezayat, S. M. [Tehran University of Medical Sciences, Department of Medical Nanotechnology, School of Advanced Technologies in Medicine (Iran, Islamic Republic of); Chen, P., E-mail: p4chen@uwaterloo.ca [University of Waterloo, Department of Chemical Engineering, Waterloo Institute for Nanotechnology (Canada); Jahanshahi, M., E-mail: mjahan@nit.ac.ir [Babol University of Technology, Nanotechnology Research Institute, Nanobiotechnology Research Group (Iran, Islamic Republic of)

    2013-01-15

    Surface morphology, surface wettability, and size distribution of biomaterials affect their in vitro and in vivo bone regeneration potential. Since nano-hydroxyapatite has a great chemical and structural similarity to natural bone and dental tissues, incorporated biomaterial of such products could improve bioactivity and bone bonding ability. In this research, nano-hydroxyapatite (23 {+-} 0.09 nm) and its composites with variety of chitosan content [2, 4, and 6 g (45 {+-} 0.19, 32 {+-} 0.12, and 28 {+-} 0.12 nm, respectively)] were prepared via an in situ hybridization route. Size distribution of the particles, protein adsorption, and calcium deposition of powders by the osteoblast cells, gene expression and percentage of new bone formation area were investigated. The highest degree of bone regeneration potential was observed in nano-hydroxyapatite powder, while the bone regeneration was lowest in nano-hydroxyapatite with 6 g of chitosan. Regarding these data, suitable size distribution next to size distribution of hydroxyapatite in bone, smaller size, higher wettability, lower surface roughness of the nano-hydroxyapatite particles and homogeneity in surface resulted in higher protein adsorption, cell differentiation and percentage of bone formation area. Results obtained from in vivo and in vitro tests confirmed the role of surface morphology, surface wettability, mean size and size distribution of biomaterial besides surface chemistry as a temporary bone substitute.

  5. Evolving application of biomimetic nanostructured hydroxyapatite.

    Science.gov (United States)

    Roveri, Norberto; Iafisco, Michele

    2010-11-09

    By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical-physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical-physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical-physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications.

  6. Comparison of characteristics of hydroxyapatite powders synthesized from cuttlefish bone via precipitation and ball milling techniques

    Science.gov (United States)

    Faksawat, K.; Kaewwiset, W.; Limsuwan, P.; Naemchanthara, K.

    2017-09-01

    The aim of this work was to compare characteristics of hydroxyapatite synthesized by precipitation and ball milling techniques. The cuttlefish bone powder was a precursor in calcium source and the di ammonium hydrogen orthophosphate powders was a precursor in phosphate source. The hydroxyapatite was synthesized by the both techniques such as precipitation and ball milling techniques. The phase formation, chemical structure and morphology of the both hydroxyapatite powders have been examined by X-ray diffractometer (XRD), Fourier transform infrared spectroscope (FTIR) and field emission scanning electron microscope (FESEM), respectively. The results show that the hydroxyapatite synthesized by precipitation technique formed hydroxyapatite phase slower than the hydroxyapatite synthesized by ball milling technique. The FTIR results show the chemical structures of sample in both techniques are similar. The morphology of the hydroxyapatite from the both techniques were sphere like shapes and particle size was about in nano scale. The average particle size of the hydroxyapatite by ball milling technique was less than those synthesized by precipitation technique. This experiment indicated that the ball milling technique take time less than the precipitation technique in hydroxyapatite synthesis.

  7. Sterilisation effect study on granular hydroxyapatite (HA).

    Science.gov (United States)

    Saidu, M F; Mashita, M; Khadijah, K; Fazan, F; Khalid, K A

    2004-05-01

    Hydroxyapatite is a calcium phosphate bioceramic that has been shown by many authors to be biocompatible with bioactive properties. It is widely accepted as the best synthetic material available for surgical use as a bone graft substitute. HA granules produced by AMREC-SIRIM from local materials underwent 5 types of sterilisation techniques with different ageing periods. Samples were tested for chemical and phase composition and microbial contamination before and after being sterilised. From the microbiological tests done, none of the unsterilised positive control yielded a positive culture. Results from X-Ray diffraction studies found that all the sterilisation techniques did not chemically degrade or structurally change the HA granules significantly.

  8. Hydroxyapatite synthesis using EDTA

    Science.gov (United States)

    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

  9. Biomineralization of nanoscale single crystal hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Omokanwaye, Tiffany [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Wilson, Otto C., E-mail: wilsono@cua.edu [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Gugssa, Ayelle; Anderson, Winston [Howard University, Department of Biology, Washington, DC (United States)

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague–Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5 nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54 nm and 0.23 nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. - Highlights: • Nanocrystalline particles were formed during in vivo implantation of crab shell using a rat model. • High resolution TEM revealed that nanoparticles were single crystals and less than 5 nm in size. • The relative distance between spots matches the expected values for hydroxyapatite.

  10. Temperature Effect on Hydroxyapatite Preparation by Co-precipitation Method under Carbamide Influence

    Directory of Open Access Journals (Sweden)

    Luo Jing

    2015-01-01

    Full Text Available Hydroxyapatite crystal was prepared by homogeneous co-precipitation method using a mixture of Calcium nitrate and diammonium phosphate as raw materials and carbamide as the buffering agent. To analyzed the influence of temperature on hydroxyapatite crystal morphology, the phase composition, crystal morphology and growth orientation were characterized by X-ray diffraction, scanning electron microscope and infrared spectrum respectively. The results show that when the reaction temperature increase from 70 °C to 95 °C, the phases composition of crystal transform from the two phases of tricalcium phosphate and eight calcium phosphate to hydroxyapatite single crystal; the morphology of the hydroxyapatite crystals transforms from nodular whisker to perfectly and compactly acicular whisker.

  11. LIBS analysis of hydroxyapatite extracted from bovine bone for Ca/P ratio measurements

    Science.gov (United States)

    Tariq, Usman; Haider, Zuhaib; Hussain, Rafaqat; Tufail, Kashif; Ali, Jalil

    2017-03-01

    Hydroxyapatite has been extensively used as a potential biocompatible ceramic in many orhtopedic applications. Hydroxyapatite is one of the members of calcium phosphate family and been used extensively as a bone substitute. The mechanical properties of hydroxyapatite itself, ceramics and bone cements prepared from hydroxyapatite vary greatly with slight variation in its Ca/P ratio. At present EDX, XRD, XRF and ICP-OES are being used for the determination of Ca/P ratio in hydroxyapatite. These techniques require special sample preparation, may also use toxic chemicals and usually are not very fast in giving the measurements. We report LIBS as a rapid alternative technique for calculation of Ca/P ratio in hydroxyapatite extracted from bovine bone (BHA). Ca/P ratio in laboratory prepared HA is calculated using LIBS and the results are validated against EDX results Ca/P ratio of the hydroxyapatite was calculated as 1.54±0.19 using LIBS while 1.63±0.03 using EDX. Ca/P ratio calculated by LIBS and EDX and showed comparable results with a difference of 5.5%. Moreover, plasma temperature and the ratio of the calcium (ion) line to calcium (atomic) line did not show significant variation in plasma conditions during measurements. The present study has demonstrated that LIBS can also be used for the determination of Ca/P ratio of hydroxyapatite and other calcium phosphates. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 24 May 2017.

  12. Surface fractal dimensions and textural properties of mesoporous alkaline-earth hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Vilchis-Granados, J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico); Granados-Correa, F., E-mail: francisco.granados@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Barrera-Díaz, C.E. [Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico)

    2013-08-15

    This work examines the surface fractal dimensions (D{sub f}) and textural properties of three different alkaline-earth hydroxyapatites. Calcium, strontium and barium hydroxyapatite compounds were successfully synthesized via chemical precipitation method and characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and N{sub 2}-physisorption measurements. Surface fractal dimensions were determined using single N{sub 2}-adsorption/desorption isotherms method to quantify the irregular surface of as-prepared compounds. The obtained materials were also characterized through their surface hydroxyl group content, determined by the mass titration method. It was found that the D{sub f} values for the three materials covered the range of 0.77 ± 0.04–2.33 ± 0.11; these results indicated that the materials tend to have smooth surfaces, except the irregular surface of barium hydroxyapatite. Moreover, regarding the synthesized calcium hydroxyapatite exhibited better textural properties compared with the synthesized strontium and barium hydroxyapatites for adsorbent purposes. However, barium hydroxyapatite shows irregular surface, indicating a high population of active sites across the surface, in comparison with the others studied hydroxyapatites. Finally, the results showed a linear correlation between the surface hydroxyl group content at the external surface of materials and their surface fractal dimensions.

  13. Computer Based Optimisation Rutines

    DEFF Research Database (Denmark)

    Dragsted, Birgitte; Olsen, Flemmming Ove

    1996-01-01

    In this paper the need for optimisation methods for the laser cutting process has been identified as three different situations. Demands on the optimisation methods for these situations are presented, and one method for each situation is suggested. The adaptation and implementation of the methods...

  14. Optimal optimisation in chemometrics

    NARCIS (Netherlands)

    Hageman, Joseph Albert

    2004-01-01

    The use of global optimisation methods is not straightforward, especially for the more difficult optimisation problems. Solutions have to be found for items such as the evaluation function, representation, step function and meta-parameters, before any useful results can be obtained. This thesis aims

  15. Influence of ferrous iron incorporation on the structure of hydroxyapatite.

    Science.gov (United States)

    Morrissey, R; Rodríguez-Lorenzo, L M; Gross, K A

    2005-05-01

    Iron is a vital element of cellular function within the body. High concentrations of iron can be found in the kidneys and the circulatory system. In bones and teeth it is present as a trace element. The use of iron-based compounds in combination with hydroxyapatite offers a new alternative for prosthetic devices. This work investigates the synthesis and processing of iron containing apatites as a possible new type of ceramic for biomedical devices. Stoichiometric and calcium deficient iron containing apatites were synthesized by a wet chemical reaction with di-ammonium-hydrogen-phosphate, calcium nitrate and a ferrous iron nitrate solution. A secondary phase of tri-calcium-phosphate (TCP) was observed after heat treatment of iron containing, calcium deficient, hydroxyapatite. The apatite structure was maintained after heat treatment of stoichiometric apatite, synthesized in the presence of iron. Sintering in air produced oxidation of Fe2+ to Fe3+, resulting in the formation of hematite as a secondary phase. The introduction of iron into the synthesis of hydroxyapatite causes: (i) an increase of the a-lattice parameter after synthesis and heat treatment in air; (ii) an increase in the c-lattice parameter after sintering in air.

  16. Interaction of some essential amino acids with synthesized poorly crystalline hydroxyapatite

    Directory of Open Access Journals (Sweden)

    A. El Rhilassi

    2016-09-01

    Full Text Available This study focused on the release of two essential amino acids, l-lysine and dl-leucine, previously adsorbed onto poorly crystalline hydroxyapatite of Ca/P = 1.59, synthesis by precipitation methods. The composition of the calcium-deficient hydroxyapatite (CDHA is chemically and structurally similar to the bone mineral. Their surface reactivity is indeed linked to the existence of hydrated surface particles (HPO42- and Ca2+. The adsorption kinetics is very fast while the release kinetics is relatively slow. The adsorption rate reached approximately 70%, but the release rate did not exceed 12%. The chemical composition of solution has an influence on the release processes. The presence of phosphate ions favored the release of amino acids, while the calcium ions inhibited it. Also, the release process is slightly influenced by Ra (ml/mg ratio and incubation temperature of the medium. The charged –COO− and NH3+ of amino acids are the strongest groups that interact with the surface of hydroxyapatite, the adsorption is mainly due to the electrostatic interaction between the groups –COO− of amino acids and calcium Ca2+ ions of the hydroxyapatite. dl-Leucine (non-polar and l-Lysine (polar–basic interact with the hydroxyapatite surface in the zwitterionic and cationic forms, respectively. The study of interactions between amino acids and hydroxyapatite is carried out in vitro by using UV–vis and infrared spectroscopy IR techniques.

  17. Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres.

    Science.gov (United States)

    Xia, Wei; Grandfield, Kathryn; Schwenke, Almut; Engqvist, Håkan

    2011-07-29

    It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

  18. Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres

    Science.gov (United States)

    Xia, Wei; Grandfield, Kathryn; Schwenke, Almut; Engqvist, Håkan

    2011-07-01

    It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

  19. Hydroxyapatite coatings for biomedical applications

    CERN Document Server

    Zhang, Sam

    2013-01-01

    Hydroxyapatite coatings are of great importance in the biological and biomedical coatings fields, especially in the current era of nanotechnology and bioapplications. With a bonelike structure that promotes osseointegration, hydroxyapatite coating can be applied to otherwise bioinactive implants to make their surface bioactive, thus achieving faster healing and recovery. In addition to applications in orthopedic and dental implants, this coating can also be used in drug delivery. Hydroxyapatite Coatings for Biomedical Applications explores developments in the processing and property characteri

  20. Is hydroxyapatite cement an alternative for allograft bone chips in bone grafting procedures? A mechanical and histological study in a rabbit cancellous bone defect model.

    NARCIS (Netherlands)

    Voor, M.J.; Arts, J.J.C.; Klein, S.A.; Walschot, L.H.B.; Verdonschot, N.J.J.; Buma, P.

    2004-01-01

    To evaluate in vivo performance of hydroxyapatite cement (HAC) as a porous bone graft substitute, HAC was mixed (1:1 ratio) with either porous calcium-phosphate granules (80% tricalcium phosphate, 20% hydroxyapatite) or defatted morsellized cancellous bone (MCB) allograft and implanted bilaterally

  1. Alternate Spray-coating for the Direct Fabrication of Hydroxyapatite Films without Crystal Growth Step in Solution.

    Science.gov (United States)

    Watanabe, Satoshi; Kashiwagi, Rei; Matsumoto, Mutsuyoshi

    2017-03-01

    We discuss an alternate spray-coating technique for the direct fabrication of hydroxyapatite films using metal masks, suction-type spray nozzles and two calcification solutions of calcium hydroxide and phosphoric acid aqueous solutions. Hydroxyapatite films were formed only on the hydrophobic surface of the substrates. Scanning electron microscopy and energy dispersive X-ray spectroscopy showed that the spray-coated films consisted of hydroxyapatite nanoparticles. The Ca/P ratio was estimated to be about 1.26. X-ray diffraction patterns of the spray-coated films almost coincided with those of the hydroxyapatite powders, showing that the spray-coated films consisted of hydroxyapatite nanoparticles. Dot arrays of hydroxyapatite films at a diameter of 100 μm were formed by tuning the concentrations of calcium hydroxide and phosphoric acid aqueous solutions. This technique allows for the direct fabrication of the hydroxyapatite films without crystal growth process in hydroxyapatite precursors, the scaffolds of crystal growth such as biocompatibility SiO2-CaO glasses, or electrophoresis processes. By using this technique, large-area ceramic films with biocompatibility will be micropatterned with minimized material consumption, short fabrication time, and reduced equipment investments.

  2. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    OpenAIRE

    Zairin Noor; Sumitro, Sutiman B.; Mohammad Hidayat; Agus Hadian Rahim; Ahmad Taufiq

    2011-01-01

    Osteoporosis is characterized by lower bone mineral density (BMD) and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to ...

  3. Thermal effects of carbonated hydroxyapatite modified by glycine and albumin

    OpenAIRE

    Gerk, S. A.; Golovanova, O. A.; Kuimova, Marina Valerievna

    2017-01-01

    In this work calcium phosphate powders were obtained by precipitation method from simulated solutions of synovial fluid containing glycine and albumin. X-ray diffraction and IR spectroscopy determined that all samples are single-phase and are presented by carbonate containing hydroxyapatite (CHA). The thermograms of solid phases of CHA were obtained and analyzed; five stages of transformation in the temperature range of 25-1000°C were marked. It is shown that in this temperature range dehydra...

  4. Cadmium immobilization by hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Smičiklas Ivana D.

    2003-01-01

    Full Text Available The contamination of air, soil and water by cadmium is a great environmental problem. If cadmium occurs in nature in ionic form, soluble in water, it easily enters into the food chain. Hydroxyapatite (HAP, Ca-o(POAe(OH2 is a sparingly soluble salt and an excellent matrix for the removal of heavy metals from solutions. Considerable research attention has been paid to the bond between Cc/2+ ions and synthetic hydroxyapatite of known composition. The sorption mechanism is complex. The dominant process is ion exchange, but surface adsorption, surface complexation and coprecipitation can also contribute to the overall mechanism. The sorption capacity depends on the characteristics of hydroxyapatite itself and on the experimental conditions. Under optimum conditions a maximum capacity of 0.8 mol Cd2+/mol HAP can be achieved. HAP is a potential sorbent for the remediation of contaminated water and soil, for industrial waste treatment, and it is also referenced as a material that can be used as a barrier around waste depositories.

  5. Optimised Renormalisation Group Flows

    CERN Document Server

    Litim, Daniel F

    2001-01-01

    Exact renormalisation group (ERG) flows interpolate between a microscopic or classical theory and the corresponding macroscopic or quantum effective theory. For most problems of physical interest, the efficiency of the ERG is constrained due to unavoidable approximations. Approximate solutions of ERG flows depend spuriously on the regularisation scheme which is determined by a regulator function. This is similar to the spurious dependence on the ultraviolet regularisation known from perturbative QCD. Providing a good control over approximated ERG flows is at the root for reliable physical predictions. We explain why the convergence of approximate solutions towards the physical theory is optimised by appropriate choices of the regulator. We study specific optimised regulators for bosonic and fermionic fields and compare the optimised ERG flows with generic ones. This is done up to second order in the derivative expansion at both vanishing and non-vanishing temperature. An optimised flow for a ``proper-time ren...

  6. Simulation versus Optimisation

    DEFF Research Database (Denmark)

    Lund, Henrik; Arler, Finn; Østergaard, Poul Alberg

    2017-01-01

    investment optimisation or optimal solutions approach. On the other hand the analytical simulation or alternatives assessment approach. Awareness of the dissimilar theoretical assumption behind the models clarifies differences between the models, explains dissimilarities in results, and provides...... a theoretical and methodological foundation for understanding and interpreting results from the two archetypes. Keywords: energy system analysis; investment optimisation models; simulations models; modelling theory;renewable energy...

  7. Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

    Science.gov (United States)

    Delbem, Alberto Carlos Botazzo; Souza, José Antonio Santos; Zaze, Ana Carolina Soares Fraga; Takeshita, Eliana Mitsue; Sassaki, Kikue Takebayashi; Moraes, João Carlos Silos

    2014-01-01

    The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite.

  8. Simple and Rapid Synthesis of Magnetite/Hydroxyapatite Composites for Hyperthermia Treatments via a Mechanochemical Route

    Science.gov (United States)

    Iwasaki, Tomohiro; Nakatsuka, Ryo; Murase, Kenya; Takata, Hiroshige; Nakamura, Hideya; Watano, Satoru

    2013-01-01

    This paper presents a simple method for the rapid synthesis of magnetite/hydroxyapatite composite particles. In this method, superparamagnetic magnetite nanoparticles are first synthesized by coprecipitation using ferrous chloride and ferric chloride. Immediately following the synthesis, carbonate-substituted (B-type) hydroxyapatite particles are mechanochemically synthesized by wet milling dicalcium phosphate dihydrate and calcium carbonate in a dispersed suspension of magnetite nanoparticles, during which the magnetite nanoparticles are incorporated into the hydroxyapatite matrix. We observed that the resultant magnetite/hydroxyapatite composites possessed a homogeneous dispersion of magnetite nanoparticles, characterized by an absence of large aggregates. When this material was subjected to an alternating magnetic field, the heat generated increased with increasing magnetite concentration. For a magnetite concentration of 30 mass%, a temperature increase greater than 20 K was achieved in less than 50 s. These results suggest that our composites exhibit good hyperthermia properties and are promising candidates for hyperthermia treatments. PMID:23629669

  9. [Optimizing the synthesis of hydroxyapatite as a method for the defluoridation of drinking water].

    Science.gov (United States)

    Ying, B; Li, X; Zheng, D; Gao, J

    2001-07-01

    As the cheaper raw materials for the synthesis of hydroxyapatite as a defluoridator, calcium hydroxide and phosphoric acid are used. Hydroxyapatite is made by a hydro-synthesis method, and optimum conditions are determined by batch test for defluoridation with respect to the consumption of phosphoric acid, reaction time and acid-washed product. The results showed that the defluoridation capacity of the synthetic hydroxyapatite for break through (F- 1.0 mg/L is considered as the break through point) was F- 5.6 mg/g in column test, and F- 10.7 mg/g for saturation in column test. After optimization of the synthesis method, the defluoridation capacity of hydroxyapatite is much higher than activated alumina and bone charcoal, which are used currently.

  10. Optimising AspectJ

    DEFF Research Database (Denmark)

    Avgustinov, Pavel; Christensen, Aske Simon; Hendren, Laurie

    2005-01-01

    AspectJ, an aspect-oriented extension of Java, is becoming increasingly popular. However, not much work has been directed at optimising compilers for AspectJ. Optimising AOP languages provides many new and interesting challenges for compiler writers, and this paper identifies and addresses three...... such challenges. First, compiling around advice efficiently is particularly challenging. We provide a new code generation strategy for around advice, which (unlike previous implementations) both avoids the use of excessive inlining and the use of closures. We show it leads to more compact code, and can also....... We present new techniques to minimise or eliminate the overhead of cflow using both intra- and inter-procedural analyses. Third, we have addressed the general problem of how to structure an optimising compiler so that traditional analyses can be easily adapted to the AOP setting. We have implemented...

  11. Optimising Magnetostatic Assemblies

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Smith, Anders

    theorem. This theorem formulates an energy equivalence principle with several implications concerning the optimisation of objective functionals that are linear with respect to the magnetic field. Linear functionals represent different optimisation goals, e.g. maximising a certain component of the field...... magnetic material can be optimised within this framework. Since in the practice most structures are realized by assembling uniformly magnetized pieces of permanent magnet, it is relevant to address the question of how a given region of space is best subdivided. This problem is investigated here within...... investigates some of the effects on the performance of magnetic systems, due to non-linear magnetic phenomena. In particular, the non-linear demagnetization effects caused by the finite coercivity of the permanent magnet material will be examined. All the optmisation techniques will be illustrated with example...

  12. Hydroxyapatite for keratoprosthesis biointegration.

    Science.gov (United States)

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

    2011-09-22

    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. 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. 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. These results are encouraging for the potential of HAp-coated surfaces for use in keratoprostheses.

  13. Pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite after pulpotomy in dog's teeth

    Directory of Open Access Journals (Sweden)

    Léa Assed Bezerra da Silva

    2006-06-01

    Full Text Available The aim of the present study was to evaluate histologically the pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite as a biomaterial pulp-capping agent in pulpotomy of dogs' teeth. Sixty pre-molar roots from three dogs were used. After pulpotomy, the remaining pulp tissue was capped with one of the following materials: Group I (20 roots: anionic lyophilized collagen matrix; Group II (20 roots: anionic lyophilized collagen matrix associated with hydroxyapatite; Group III (10 roots: calcium hydroxide (p.a. paste in saline; Group IV (10 roots: zinc oxide eugenol cement. After 90 days the animals were killed by anesthetic overdose and the teeth were removed and submitted to histological processing. According to the histopathological results, we concluded that the zinc oxide eugenol cement and anionic lyophilized collagen matrix with or without hydroxyapatite did not present satisfactory pulp response and that calcium hydroxide is the suitable material for pulpotomy.

  14. [Regulation of adherence to serum-coated hydroxyapatite by Streptococcus sanguis].

    Science.gov (United States)

    Song, X; Pan, Y; Kong, Q

    1999-05-01

    To investigate the effects of pH and calcium iron on adhesion of Streptococcus sanguis to serum-coated hydroxyapatite. The adhesion model in vitro established by Clark W. B. in 1977 was used to quantify adsorptive cells through [3H] thymidine labelling. The cpm values between different pH groups showed significant differences. Also, there were significant differences of cpm values between calcium groups and control group. Either pH or calcium iron has obvious effect on adherence of Stroptococcus sanguis to serum-coated hydroxyapatite. The findings suggest that regulating pH and concentration of calcium iron can help to change colonization on teeth surfaces by Streptococcus sanguis in periodontal circumstance.

  15. Development of calcium phosphate based apatite from hen's eggshell

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Stoichiometric hydroxyapatite with Ca/P molar ratio, 1⋅67, was synthesized using hen's eggshell as calcium source and phosphoric acid by precipitation method. Conventional EDTA titration and gravimetric methods were adopted to estimate the amount of calcium and phosphorous, respectively. Fourier-transform.

  16. In situ ring-opening polymerization of hydroxyapatite/poly (ethylene ...

    Indian Academy of Sciences (India)

    In vitro bioactivity of the HAp/PEA--PET composites was studied by soaking in simulated body fluid (SBF) under the flowing system at the rate of 130 mL/day for 7, 14, 21 and 28 days. The formation of hydroxyapatite nanocrystals was observed on the composite surfaces through the consumption of calcium and ...

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

    Science.gov (United States)

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

    2015-03-20

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

  18. Open-Porous Hydroxyapatite Scaffolds for Three-Dimensional Culture of Human Adult Liver Cells

    Science.gov (United States)

    Schmelzer, Eva; Over, Patrick; Nettleship, Ian; Gerlach, Joerg C.

    2016-01-01

    Liver cell culture within three-dimensional structures provides an improved culture system for various applications in basic research, pharmacological screening, and implantable or extracorporeal liver support. Biodegradable calcium-based scaffolds in such systems could enhance liver cell functionality by providing endothelial and hepatic cell support through locally elevated calcium levels, increased surface area for cell attachment, and allowing three-dimensional tissue restructuring. Open-porous hydroxyapatite scaffolds were fabricated and seeded with primary adult human liver cells, which were embedded within or without gels of extracellular matrix protein collagen-1 or hyaluronan. Metabolic functions were assessed after 5, 15, and 28 days. Longer-term cultures exhibited highest cell numbers and liver specific gene expression when cultured on hydroxyapatite scaffolds in collagen-1. Endothelial gene expression was induced in cells cultured on scaffolds without extracellular matrix proteins. Hydroxyapatite induced gene expression for cytokeratin-19 when cells were cultured in collagen-1 gel while culture in hyaluronan increased cytokeratin-19 gene expression independent of the use of scaffold in long-term culture. The implementation of hydroxyapatite composites with extracellular matrices affected liver cell cultures and cell differentiation depending on the type of matrix protein and the presence of a scaffold. The hydroxyapatite scaffolds enable scale-up of hepatic three-dimensional culture models for regenerative medicine applications. PMID:27403430

  19. Microstructural Improvement of Hydroxyapatite-ZrO2 Composite Ceramics via Thermal Precipitation Techniques.

    Science.gov (United States)

    Sangmala, A.; Limsuwan, P.; Kaewwiset, W.; Naemchanthara, K.

    2017-09-01

    Hydroxyapatite-ZrO2 composite ceramic were synthesized using a thermal precipitation techniques. The chemical precursors were prepared from di-ammonium hydrogen orthophosphate, calcium oxide (CaO) derived from chicken eggshell, zirconium dioxide (ZrO2) and distilled water. The mixture were heated at the various temperatures from 100 to 700 °C in the furnace with an incremental temperature of 100 °C. The ZrO2 contents in the composite ceramic were varied from 0 to 15 percent weight of CaO. The prepared composites were then annealed at 300, 600 and 700 °C for 4 h in air. The crystal structure, function group and morphology of all samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and universal testing machine (UTM), respectively. The results indicated that the undoped-ZrO2 samples hydroxyapatite phase with a hexagonal structure. However, the hydroxyapatite was transformed to the tri-calcium phosphate after thermal treatment at 700 °C. For the doped-ZrO2 samples, the hydroxyapatite and ZrO2 phases were found. Moreover, the result showed that the compressive strength of hydroxyapatite-ZrO2 composite ceramic increased with increasing the ZrO2 content.

  20. Effect of Metal Ions of Chlorapatites on the Topotaxial Replacement by Hydroxyapatite under Hydrothermal Conditions

    Science.gov (United States)

    Rendón-Angeles, J. C.; Yanagisawa, K.; Ishizawa, N.; Oishi, S.

    2000-11-01

    The effect of the metal ions in the chlorapatite structure on the topotaxial conversion to the hydroxyapatite structure was investigated, using three different types of chlorapatite single crystals, calcium, strontium, and barium chlorapatite. The topotaxial conversion to the hydroxyapatite structure was conducted under hydrothermal conditions at a range of temperature from 300 to 800°C for intervals between 3 and 96 h in concentrated KOH solutions. The Cl- ion exchange in the calcium and strontium chlorapatite crystals was completed at 500 and 700°C in a 6.25 M KOH solution, respectively, which resulted in the formation of hydroxyapatite structure. The transformed crystals retained their original shape and dimensions due to the topotaxial transformation. In contrast, the rate of the topotaxial conversion was further reduced on the barium chlorapatite crystals that contain metal ions with large size such as Ba. These crystals were only partially converted to hydroxyapatite even at 800°C in 10 M KOH solution. Under these conditions, a dissolution of ion species of the topotaxially converted barium hydroxyapatite layer was observed, which resulted in the precipitation of new crystals on the surface of the remaining barium chlorapatite crystals. The structure of the new crystals was matched with the hexagonal apatite structure, but a great amount of K was incorporated in the structure.

  1. Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method.

    Science.gov (United States)

    Ming, Jinfa; Liu, Zhi; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

    2014-04-01

    Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6±20.4nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. In Vitro Evaluation of Nanoscale Hydroxyapatite-Based Bone Reconstructive Materials with Antimicrobial Properties.

    Science.gov (United States)

    Ajduković, Zorica R; Mihajilov-Krstev, Tatjana M; Ignjatović, Nenad L; Stojanović, Zoran; Mladenović-Antić, Snezana B; Kocić, Branislava D; Najman, Stevo; Petrović, Nenad D; Uskoković, Dragan P

    2016-02-01

    In the field of oral implantology the loss of bone tissue prevents adequate patient care, and calls for the use of synthetic biomaterials with properties that resemble natural bone. Special attention is paid to the risk of infection after the implantation of these materials. Studies have suggested that some nanocontructs containing metal ions have antimicrobial properties. The aim of this study was to examine the antimicrobial and hemolytic activity of cobalt-substituted hydroxyapatite nanoparticles, compared to hydroxyapatite and hydroxyapatite/poly-lactide-co-glycolide. The antibacterial effects of these powders were tested against two pathogenic bacterial strains: Escherichia coi (ATCC 25922) and Staphylococcus aureus (ATCC 25923), using the disc diffusion method and the quantitative antimicrobial test in a liquid medium. The quantitative antimicrobial test showed that all of the tested biomaterials have some antibacterial properties. The effects of both tests were more prominent in case of S. aureus than in E coli. A higher percentage of cobalt in the crystal structure of cobalt-substituted hydroxyapatite nanoparticles led to an increased antimicrobial activity. All of the presented biomaterial samples were found to be non-hemolytic. Having in mind that the tested of cobalt-substituted hydroxyapatite (Ca/Co-HAp) material in given concentrations shows good hemocompatibility and antimicrobial effects, along with its previously studied biological properties, the conclusion can be reached that it is a potential candidate that could substitute calcium hydroxyapatite as the material of choice for use in bone tissue engineering and clinical practices in orthopedic, oral and maxillofacial surgery.

  3. Reassigning the most stable surface of hydroxyapatite to the water resistant hydroxyl terminated (010) surface

    Science.gov (United States)

    Zeglinski, Jacek; Nolan, Michael; Thompson, Damien; Tofail, Syed A. M.

    2014-05-01

    Understanding the surface stability and crystal growth morphology of hydroxyapatite is important to comprehend bone growth and repair processes and to engineer protein adsorption, cellular adhesion and biomineralization on calcium phosphate based bone grafts and implant coatings. It has generally been assumed from electronic structure calculations that the most stable hydroxyapatite surface is the (001) surface, terminated just above hydroxyl ions perpendicular to the {001} crystal plane. However, this is inconsistent with the known preferential growth direction of hydroxyapatite crystals and previous experimental work which indicates that, contrary to currently accepted theoretical predictions, it is actually the (010) surface that is preferentially exposed. The surface structure of the (010) face is still debated and needs reconciliation. In this work, we use a large set of density functional theory calculations to model the interaction of water with hydroxyapatite surfaces and probe the surface stability and resistance to hydrolytic remodeling of a range of surface faces including the (001) surface and the phosphate-exposed, calcium-exposed, and hydroxyl-exposed terminations of the (010) surface. For the (001) surface and the phosphate-exposed (010) surface, dissociative water adsorption is favorable. In contrast, the hydroxyl-terminated (010) surface will not split water and only molecular adsorption of water is possible. Our calculations show, overall, that the hydroxyl-terminated (010) surface is the most stable and thus should be the predominant form of the hydroxyapatite surface exposed in experiments. This finding reconciles discrepancies between the currently proposed surface terminations of hydroxyapatite and the experimentally observed crystal growth direction and surface stability, which may aid efforts to accelerate biomineralization and better control bone-repair processes on hydroxyapatite surfaces.

  4. Antibacterial coatings of fluoridated hydroxyapatite for percutaneous implants.

    Science.gov (United States)

    Ge, Xiang; Leng, Yang; Bao, Chongyun; Xu, Sherry Li; Wang, Renke; Ren, Fuzeng

    2010-11-01

    Percutaneous orthopedic and dental implants require not only good adhesion with bone but also the ability to attach and form seals with connective tissues and the skin. To solve the skin-seal problem of such implants, an electrochemical deposition method was used to modify the surfaces of metallic implants to improve their antibacterial ability and skin seals around them. A dense and uniform fluoridated calcium phosphate coating with a thickness of about 200 nm was deposited on an acid-etched pure titanium substrate by controlling the current density and reaction duration of the electrochemical process. The as-deposited amorphous fluoridated calcium phosphate transformed to fluoridated hydroxyapatite (FHA) after heat treatment at 600°C in a water vapor environment for 3 h. Both single crystal diffraction patterns and high-resolution transmission electron microscope (HRTEM) images confirmed the phase of the fluoridated calcium phosphate after the heat treatment. The antibacterial activities of FHA coatings were tested against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Porphyromonas gingivalis (P. gingivalis) with the film attachment method. The antibacterial activity of FHA coating is much higher than that of pure hydroxyapatite (HA) coating and acid-etched pure titanium surface. The promising features of FHA coating make it suitable for orthopedic and dental applications.

  5. Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

    Science.gov (United States)

    Chadda, Harshita; Naveen, Sangeetha Vasudevaraj; Mohan, Saktiswaren; Satapathy, Bhabani K; Ray, Alok R; Kamarul, Tunku

    2016-07-01

    Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail. The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination. Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software. Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis. The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  6. Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2016-02-01

    In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

  7. Variability of hydroxyapatite preparations.

    Science.gov (United States)

    Young, R A; Holcomb, D W

    1982-01-01

    Hydroxyapatite synthesized by various "standard" ways exhibits marked differences with preparation method. Specimens were prepared with two precipitation methods, a reflux method, a hydrothermal method, a high-temperature (1000 degrees C) solid-state reaction method, and by conversion of chlorapatite at 1000 degrees C. They were compared in detail by use of several techniques, the major ones being x-ray diffraction including Rietveld structure refinements, quantitative i.r. analyses, and deuteration kinetics studies. At least some of the specimens differed with respect to each of the approximately 14 properties measured. The major lattice parameter differences could be largely accounted for by structurally incorporated H2O, CO2-3, and + O2- for 2(OH)-. Deuterizability was used as an indicator of ease of diffusion along the X-ion channels, a property that may be related to dissolution kinetics. The differently prepared specimens differed in deuterizability by at least two orders of magnitude. The high-temperature preparations, which were monoclinic, deuterated little at 110 degrees C, even in 1000 h. The precipitated and reflux specimens deuterated readily. There were general indications of correlation between ease of diffusion and features providing passing sites for the diffusing species, e.g., OH- disorder, vacancies, and distortions in the walls of the X-ion channels (mostly by CO3 for PO4), and possibly OH- vacancies. Correlation of structural H2O, present in the aqueous preparations, with ease of diffusion is still ambiguous.

  8. Crystal Structure and Carbonate Species into Structure of Hydroxyapatite

    OpenAIRE

    元上, 康孝; 管野, 亨; 小林, 正義; 赤澤, 敏之; MOTOGAMI, Yasutaka; KANNO, Tohru; Kobayashi, Masayoshi; Akazawa, Toshiyuki

    1998-01-01

    The morphology of hydroxyapatite (HAp) had a significant effect on carbonates incorporated into HAp structures. A cattle bone-originated HAp (r-HAp) had two carbonates, OH-substituted and P04- substituted, and chemically synthesized HAp (s-HAp) had only the latter carbonate. This difference was ascribed to the increased calcium deficiency of r-HAp. Partial substitution of Sr for Ca caused expansion of the P-O bond and subjected the HAp structure to stress. This stress decreased the decomposit...

  9. Hybrid organic-inorganic materials based on hydroxyapatite structure

    Energy Technology Data Exchange (ETDEWEB)

    Moussa, Sana Ben; Bachouâ, Hassen [U.R. Matériaux et synthèse organique UR17ES31, Institut Préparatoire aux Etudes d’Ingénieur de Monastir, Université de Monastir, 5019 Monastir (Tunisia); Gruselle, Michel, E-mail: michel.gruselle@upmc.fr [Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris (France); Beaunier, Patricia [Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 7197, Laboratoire de Réactivité de Surface, F-75005 Paris (France); Flambard, Alexandrine [Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris (France); Badraoui, Béchir [U.R. Matériaux et synthèse organique UR17ES31, Institut Préparatoire aux Etudes d’Ingénieur de Monastir, Université de Monastir, 5019 Monastir (Tunisia)

    2017-04-15

    The present article details the formation of calcium hydroxyapatite synthesized by the hydrothermal way, in presence of glycine or sarcosine. The presence of these amino-acids during the synthetic processes reduces the crystalline growthing through the formation of hybrid organic-inorganic species The crystallite sizes are decreasing and the morphology is modified with the increase of the amino-acid concentration. - Graphical abstract: Formation of Ca carboxylate salt leading to the grafting of glycine and sarcosine on the Ca=Hap surface (R= H, CH3).

  10. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results. This com......A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results...

  11. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  12. Eggshell-Derived Hydroxyapatite: A New Era in Bone Regeneration.

    Science.gov (United States)

    Kattimani, Vivekanand; Lingamaneni, Krishna Prasad; Chakravarthi, Pandi Srinivas; Kumar, T S Sampath; Siddharthan, Arjunan

    2016-01-01

    Defects of maxillofacial skeleton lead to personal (functional and aesthetic), social and behavioral problems; which make the person to isolate from the main stream of society. So, bone regeneration is the need for proper structure, function, and aesthetics following cyst enucleation, trauma, and tumor ablative surgery; which helps for overall health of the individual. The preliminary study is planned to evaluate and compare the efficacy of eggshell-derived hydroxyapatite (EHA) and synthetic hydroxyapatite (SHA) following cystectomy. Microwave-processed calcium deficient EHA and commercially available SHA are used for grafting. Total 20 patients enrolled in this study, consisting 10 in each group between 20 and 45 years of age. All the patients were evaluated for bone regeneration at first, second, third, and sixth month's interval, postsurgically, using radiovisiograph and clinical parameters. The bone formation characteristics vary at second month when compared to SHA. This difference may be because of the kinetics involved in the regeneration pattern. The pattern of bone healing was trabecular after third month, indicating complete bone formation. The study showed constant raise of density and remained same at the end of study period. Both EHA and SHA graft materials are equally efficient in early bone regeneration. Within the limitations of this study the EHA showed promising results. Which indicates the eggshell waste-bio mineral is worthwhile raw material for the production of HA and is a Go Green procedure. Eggshell-derived hydroxyapatite is economic, compared with SHA.

  13. Optimisation of Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    H. El Hamchary

    1996-04-01

    Full Text Available When choosing the most appropriate microstrip antenna configuration for particular applications, the kind of excitation of the radiating element is an essential factor that requires careful considerations. For controlling the distribution of energy of the linear or planar array of elements and for coupling energy to the individual elements, a wide variety of feed mechanisms are available. In this paper, the coaxial antenna feeding is assumed and the best (optimised feeding is found. Then, antenna characteristics such as radiation pattern, return loss, input impedance, and VSWR are obtained.

  14. Biomimetic growth of hydroxyapatite on gelatin films doped with sodium polyacrylate.

    Science.gov (United States)

    Bigi, A; Boanini, E; Panzavolta, S; Roveri, N

    2000-01-01

    Gelatin films were used as biomimetic substrates for the nucleation of hydroxyapatite from simulated body fluid (SBF). Stretching and presence of sodium polyacrylate appear to be essential factors for the specific nucleation and growth of hydroxyapatite crystals inside the films. After soaking in 1.5SBF for periods longer than 4 days, all the films display a completely calcified surface. However, the spherical aggregates on the film surfaces do not give any X-ray diffraction effect and exhibit a low Ca/P molar ratio, typical of amorphous calcium phosphate. The ordered deposition of crystalline hydroxyapatite has been verified to take place only in stretched polyacrylate--gelatin films. The crystals grow as tablets about 2 microns thick among the gelatin layers, with their crystallographic c-axes preferentially oriented parallel to the direction of orientation of the collagen molecules, thus resembling the parallel orientation of apatitic crystals and collagen fibrils in calcified biological tissues.

  15. Hollow carbonated hydroxyapatite microspheres with mesoporous structure: hydrothermal fabrication and drug delivery property.

    Science.gov (United States)

    Guo, Ya-Jun; Wang, Ying-Ying; Chen, Ting; Wei, Yi-Ting; Chu, Lian-Feng; Guo, Ya-Ping

    2013-08-01

    Hollow carbonated hydroxyapatite microspheres with mesoporous structure (HCHAs) have been fabricated by using calcium carbonated microspheres as sacrificial templates according to the following routes: (i) the in situ deposit of carbonated hydroxyapatite on the surfaces of CaCO3 microspheres by hydrothermal method and (ii) the removal of CaCO3 by chemical etching. The HCHAs consist of a hollow core and a mesoporous shell. Interestingly, the shell of the microspheres is constructed by carbonated hydroxyapatite nanoplates as building blocks. Moreover, these nanoplates are composed of many smaller nanoparticles with different crystal orientations, and the mesopores exist among these nanoparticles. The HCHAs exhibit the high drug-loading capacity and sustained drug release property, suggesting that the hierarchically porous microspheres have great potentials for bone-implantable drug-delivery applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Nucleation and growth of hydroxyapatite nanocrystals for nondestructive repair of early caries lesions

    Science.gov (United States)

    Onuma, Kazuo; Yamagishi, Kazue; Oyane, Ayako

    2005-08-01

    Characterization of synthetic enamel formed by newly developed dental paste for repairing early caries lesions was performed using scanning and transmission electron microscopies and atomic force microscopy, with the chemical composition analysis using X-ray photoelectron spectroscopy. It was shown that the hydroxyapatite nanocrystals seamlessly grew in the interface between the paste and tooth enamel, and arranged their (0 0 0 1) face parallel to the tooth surface same as enamel apatite. The rapid growth of high crystalline large hydroxyapatite crystals by applying the paste is attributed to the dissociation of calcium phosphate clusters, Ca 9(PO 4) 6, which is the main growth unit of hydroxyapatite when it grows under physiological conditions, to ionic species in the concentrated and low pH phosphate solution.

  17. Simple Combinatorial Optimisation Cost Games

    NARCIS (Netherlands)

    van Velzen, S.

    2005-01-01

    In this paper we introduce the class of simple combinatorial optimisation cost games, which are games associated to {0, 1}-matrices.A coalitional value of a combinatorial optimisation game is determined by solving an integer program associated with this matrix and the characteristic vector of the

  18. Effect of Hydroxyapatite on Bone Integration in a Rabbit Tibial Defect Model

    Science.gov (United States)

    Sohn, Sung-Keun; Kim, Kyung-Taek; Kim, Chul-Hong; Ahn, Hee-Bae; Rho, Mee-Sook; Jeong, Min-Ho; Sun, Sang-Kyu

    2010-01-01

    Background The aim of the present study was to prepare hydroxyapatite (HA) and then characterize its effect on bone integration in a rabbit tibial defect model. The bone formation with different designs of HA was compared and the bony integration of several graft materials was investigated qualitatively by radiologic and histologic study. Methods Ten rabbits were included in this study; two holes were drilled bilaterally across the near cortex and the four holes in each rabbit were divided into four treatment groups (HAP, hydroxyapatite powder; HAC, hydroxyapatite cylinder; HA/TCP, hydroxyapatite/tri-calcium phosphate cylinder, and titanium cylinder). The volume of bone ingrowth and the change of bone mineral density were statistically calculated by computed tomography five times for each treatment group at 0, 2, 4, 6, and 8 weeks after grafting. Histologic analysis was performed at 8 weeks after grafting. Results The HAP group showed the most pronounced effect on the bone ingrowth surface area, which seen at 4, 6, and 8 weeks after graft (p 0.05). On histological examination, the HAP group revealed well-recovered cortical bone, but the bone was irregularly thickened and haphazardly admixed with powder. The HAC group showed similar histological features to those of the HA/TCP group; the cortical surface of the newly developed bone was smooth and the bone matrix on the surface of the cylinder was regularly arranged. Conclusions We concluded that both the hydroxyapatite powder and cylinder models investigated in our study may be suitable as a bone substitute in the rabbit tibial defect model, but their characteristic properties are quite different. In contrast to hydroxyapatite powder, which showed better results for the bone ingrowth surface, the hydroxyapatite cylinder showed better results for the sustained morphology. PMID:20514266

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

    Science.gov (United States)

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

    2016-03-01

    The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80 wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10 wt.% CHX and 0, 10, 20 or 40 wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4 weeks. XRD peak width and SEM images suggested this was due to the very small size (~10 nm) of the hydroxyapatite crystallites. Precipitate mass at 12 weeks was 22 wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7 wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1 week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12 weeks CHX formed 5 to 15% of the HA layer with 10 to 40 wt.% CaP respectively. Despite linear decline of strength and modulus in 4 weeks from 160 to 101 MPa and 4 to 2.4 GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Risedronate/zinc-hydroxyapatite based nanomedicine for osteoporosis

    Energy Technology Data Exchange (ETDEWEB)

    Khajuria, Deepak Kumar, E-mail: deepak_kumarkhajuria@yahoo.co.in [Laboratory for Integrative Multiscale Engineering Materials and Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Department of Pharmacology, Al-Ameen College of Pharmacy, Bangalore 560027 (India); Disha, Choudhary [Department of Pharmacology, Al-Ameen College of Pharmacy, Bangalore 560027 (India); Vasireddi, Ramakrishna [Laboratory for Integrative Multiscale Engineering Materials and Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Razdan, Rema [Department of Pharmacology, Al-Ameen College of Pharmacy, Bangalore 560027 (India); Mahapatra, D. Roy [Laboratory for Integrative Multiscale Engineering Materials and Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India)

    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. - Highlights: • Risedronate functionalized zinc-hydroxyapatite nanoparticles were prepared. • Risedronate was used as a carrier to deliver zinc-hydroxyapatite nanoparticles to bones. • Application of risedronate/ZnHA drug formulation in osteoporosis is described.

  1. Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

    Science.gov (United States)

    Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

    2015-03-01

    Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Subsampling for dataset optimisation

    Science.gov (United States)

    Ließ, Mareike

    2017-04-01

    Soil-landscapes have formed by the interaction of soil-forming factors and pedogenic processes. In modelling these landscapes in their pedodiversity and the underlying processes, a representative unbiased dataset is required. This concerns model input as well as output data. However, very often big datasets are available which are highly heterogeneous and were gathered for various purposes, but not to model a particular process or data space. As a first step, the overall data space and/or landscape section to be modelled needs to be identified including considerations regarding scale and resolution. Then the available dataset needs to be optimised via subsampling to well represent this n-dimensional data space. A couple of well-known sampling designs may be adapted to suit this purpose. The overall approach follows three main strategies: (1) the data space may be condensed and de-correlated by a factor analysis to facilitate the subsampling process. (2) Different methods of pattern recognition serve to structure the n-dimensional data space to be modelled into units which then form the basis for the optimisation of an existing dataset through a sensible selection of samples. Along the way, data units for which there is currently insufficient soil data available may be identified. And (3) random samples from the n-dimensional data space may be replaced by similar samples from the available dataset. While being a presupposition to develop data-driven statistical models, this approach may also help to develop universal process models and identify limitations in existing models.

  3. Novel Development of Phosphate Treated Porous Hydroxyapatite

    Science.gov (United States)

    Doi, Kazuya; Abe, Yasuhiko; Kobatake, Reiko; Okazaki, Yohei; Oki, Yoshifumi; Naito, Yoshihito; Prananingrum, Widyasri; Tsuga, Kazuhiro

    2017-01-01

    Phosphoric acid-etching treatment to the hydroxyapatite (HA) surface can modify the solubility calcium structure. The aim of the present study was to develop phosphate treated porous HA, and the characteristic structures and stimulation abilities of bone formation were evaluated to determine its suitability as a new type of bone graft material. Although the phosphoric acid-etching treatment did not alter the three-dimensional structure, a micrometer-scale rough surface topography was created on the porous HA surface. Compared to porous HA, the porosity of phosphate treated porous HA was slightly higher and the mechanical strength was lower. Two weeks after placement of the cylindrical porous or phosphate treated porous HA in a rabbit femur, newly formed bone was detected in both groups. At the central portion of the bone defect area, substantial bone formation was detected in the phosphate treated porous HA group, with a significantly higher bone formation ratio than detected in the porous HA group. These results indicate that phosphate treated porous HA has a superior surface topography and bone formation abilities in vivo owing to the capacity for both osteoconduction and stimulation abilities of bone formation conferred by phosphoric acid etching.

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

    Science.gov (United States)

    Kim, Hae-Won; Kim, Hyoun-Ee

    2006-05-01

    In this study, we produced hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) bioceramics as a novel geometrical form, the nanoscale fiber, for the biomedical applications. Based on the sol-gel precursors of the apatites, an electrospinning technique was introduced to generate nanoscale fibers. The diameter of the fibers was exploited in the range of a few micrometers to hundreds of nanometers (1.55 microm-240 nm) by means of adjusting the concentration of the sols. Through the fluoridation of apatite, the solubility of the fiber was tailored and the fluorine ions were well released from the FHA. The HA and FHA nanofibers produced in this study are considered to find potential applications in the biomaterials and tissue engineering fields. (c) 2005 Wiley Periodicals, Inc.

  5. Efficacy of the biomaterials 3wt%-nanostrontium-hydroxyapatite-enhanced calcium phosphate cement (nanoSr-CPC) and nanoSr-CPC-incorporated simvastatin-loaded poly(lactic-co-glycolic-acid) microspheres in osteogenesis improvement: An explorative multi-phase experimental in vitro/vivo study.

    Science.gov (United States)

    Masaeli, Reza; Jafarzadeh Kashi, Tahereh Sadat; Dinarvand, Rassoul; Rakhshan, Vahid; Shahoon, Hossein; Hooshmand, Behzad; Mashhadi Abbas, Fatemeh; Raz, Majid; Rajabnejad, Alireza; Eslami, Hossein; Khoshroo, Kimia; Tahriri, Mohammadreza; Tayebi, Lobat

    2016-12-01

    The purpose of this multi-phase explorative in vivo animal/surgical and in vitro multi-test experimental study was to (1) create a 3wt%-nanostrontium hydroxyapatite-enhanced calcium phosphate cement (Sr-HA/CPC) for increasing bone formation and (2) creating a simvastatin-loaded poly(lactic-co-glycolic acid) (SIM-loaded PLGA) microspheres plus CPC composite (SIM-loaded PLGA+nanostrontium-CPC). The third goal was the extensive assessment of multiple in vitro and in vivo characteristics of the above experimental explorative products in vitro and in vivo (animal and surgical studies). Physical and chemical properties of the prepared Sr-HA/CPC were evaluated. MTT assay and alkaline phosphatase activities, and radiological and histological examinations of Sr-HA/CPC, CPC and negative control were compared. X-ray diffraction (XRD) indicated that crystallinity of the prepared cement increased by increasing the powder-to-liquid ratio. Incorporation of Sr-HA into CPC increased MTT assay (biocompatibility) and ALP activity (P<0.05). Histomorphometry showed greater bone formation after 4weeks, after implantation of Sr-HA/CPC in 10 rats compared to implantations of CPC or empty defects in the same rats (n=30, ANOVA P<0.05). METHODS AND RESULTS PERTAINING TO SIM-LOADED PLGA MICROSPHERES+NANOSTRONTIUM-CPC COMPOSITE: After SEM assessment, the produced composite of microspheres and enhanced CPC were implanted for 8weeks in 10 rabbits, along with positive and negative controls, enhanced CPC, and enhanced CPC plus SIM (n=50). In the control group, only a small amount of bone had been regenerated (localized at the boundary of the defect); whereas, other groups showed new bone formation within and around the materials. A significant difference was found in the osteogenesis induced by the groups sham control (16.96±1.01), bone materials (32.28±4.03), nanostrontium-CPC (24.84±2.6), nanostrontium-CPC-simvastatin (40.12±3.29), and SIM-loaded PLGA+nanostrontium-CPC (44.8±6.45) (ANOVA P

  6. Mg-containing hydroxyapatite coatings produced by plasma electrolytic oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Cesar Augusto; Rangel, Elidiane Cipriano; Durrant, Steven Frederick; Cruz, Nilson Cristino da, E-mail: cesar.augustoa@hotmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil). Lab. de Plasmas Tecnologicos; Delgado-Silva, Adriana de Oliveira [Universidade Federal de Sao Carlos (UFSCar), Sorocaba, SP (Brazil); Tabacniks, Manfredo H. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica

    2017-07-15

    Plasma Electrolytic Oxidation (PEO) is promising for the processing of biomaterials because it enables the production of surfaces with adjustable composition and structure. In this work, aimed at the improvement of the bioactivity of titanium, PEO has been used to grow calcium phosphide coatings on titanium substrates. The effects of the addition of magnesium acetate to the electrolytes on the composition of the coatings produced during 120 s on Ti disks using bipolar voltage pulses and solutions of calcium and magnesium acetates and sodium glycerophosphate as electrolytes have been studied. Scanning electron microscopy, X-ray energy dispersive spectroscopy, Rutherford backscattering spectroscopy, X-ray diffractometry with Rietveld refinement and profilometry were used to characterize the modified samples. Coatings composed of nearly 50 % of Mg-doped hydroxyapatite have been produced. In certain conditions up to 4% Mg can be incorporated into the coating without any observable significant structural modifications of the hydroxyapatite. (author)

  7. Optimisation of the Laser Cutting Process

    DEFF Research Database (Denmark)

    Dragsted, Birgitte; Olsen, Flemmming Ove

    1996-01-01

    The problem in optimising the laser cutting process is outlined. Basic optimisation criteria and principles for adapting an optimisation method, the simplex method, are presented. The results of implementing a response function in the optimisation are discussed with respect to the quality as well...

  8. Application of Calcium Phosphate Materials in Dentistry

    Directory of Open Access Journals (Sweden)

    Jabr S. Al-Sanabani

    2013-01-01

    Full Text Available Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1 application of calcium phosphate into various fields in dentistry; (2 improving mechanical properties of calcium phosphate; (3 biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

  9. Calcium Carbonate

    Science.gov (United States)

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  10. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  11. Isogeometric Analysis and Shape Optimisation

    DEFF Research Database (Denmark)

    Gravesen, Jens; Evgrafov, Anton; Gersborg, Allan Roulund

    One of the attractive features of isogeometric analysis is the exact representation of the geometry. The geometry is furthermore given by a relative low number of control points and this makes isogeometric analysis an ideal basis for shape optimisation. I will describe some of the results we have...... obtained and also some of the problems we have encountered. One of these problems is that the geometry of the shape is given by the boundary alone. And, it is the parametrisation of the boundary which is changed by the optimisation procedure. But isogeometric analysis requires a parametrisation...... of the whole domain. So in every optimisation cycle we need to extend a parametrisation of the boundary of a domain to the whole domain. It has to be fast in order not to slow the optimisation down but it also has to be robust and give a parametrisation of high quality. These are conflicting requirements so we...

  12. Medicines optimisation: priorities and challenges.

    Science.gov (United States)

    Kaufman, Gerri

    2016-03-23

    Medicines optimisation is promoted in a guideline published in 2015 by the National Institute for Health and Care Excellence. Four guiding principles underpin medicines optimisation: aim to understand the patient's experience; ensure evidence-based choice of medicines; ensure medicines use is as safe as possible; and make medicines optimisation part of routine practice. Understanding the patient experience is important to improve adherence to medication regimens. This involves communication, shared decision making and respect for patient preferences. Evidence-based choice of medicines is important for clinical and cost effectiveness. Systems and processes for the reporting of medicines-related safety incidents have to be improved if medicines use is to be as safe as possible. Ensuring safe practice in medicines use when patients are transferred between organisations, and managing the complexities of polypharmacy are imperative. A medicines use review can help to ensure that medicines optimisation forms part of routine practice.

  13. In vivo performance of novel soybean/gelatin-based bioactive and injectable hydroxyapatite foams

    OpenAIRE

    Kovtun, Anna; Goeckelmann, Melanie J.; Niclas, Antje A.; Montufar, Edgar B.; Ginebra, Maria-Pau; Planell, Josep A.; Santin, Matteo; Ignatius, Anita

    2015-01-01

    Major limitations of calcium phosphate cements (CPCs) are their relatively slow degradation rate and the lack of macropores allowing the ingrowth of bone tissue. The development of self-setting cement foams has been proposed as a suitable strategy to overcome these limitations. In previous work we developed a gelatine-based hydroxyapatite foam (G-foam), which exhibited good injectability and cohesion, interconnected porosity and good biocompatibility in vitro. In the present study we evaluate...

  14. X-Ray Diffraction Studies on the Thermal Stability of Calcium ...

    African Journals Online (AJOL)

    acer

    Available online at http://www.ajol.info/browse-journals. Nigerian Journal of Basic ... ABSTRACT: Calcium-Strontium hydroxyapatite (HAP) solid solutions in the presence and absence of diethylamine (DEA) ... atomic absorption spectroscopy (AAS) and UV- visible spectrometry revealed that calcium –strontium. HAP solid ...

  15. SPS batch spacing optimisation

    CERN Document Server

    Velotti, F M; Carlier, E; Goddard, B; Kain, V; Kotzian, G

    2017-01-01

    Until 2015, the LHC filling schemes used the batch spac-ing as specified in the LHC design report. The maximumnumber of bunches injectable in the LHC directly dependson the batch spacing at injection in the SPS and hence onthe MKP rise time.As part of the LHC Injectors Upgrade project for LHCheavy ions, a reduction of the batch spacing is needed. In thisdirection, studies to approach the MKP design rise time of150ns(2-98%) have been carried out. These measurementsgave clear indications that such optimisation, and beyond,could be done also for higher injection momentum beams,where the additional slower MKP (MKP-L) is needed.After the successful results from 2015 SPS batch spacingoptimisation for the Pb-Pb run [1], the same concept wasthought to be used also for proton beams. In fact, thanksto the SPS transverse feed back, it was already observedthat lower batch spacing than the design one (225ns) couldbe achieved. For the 2016 p-Pb run, a batch spacing of200nsfor the proton beam with100nsbunch spacing wasreque...

  16. Optimisation of load control

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, P. [VTT Energy, Espoo (Finland)

    1998-08-01

    Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

  17. Determination of Ca/P molar ratio in hydroxyapatite (HA) by X-ray fluorescence technique

    Energy Technology Data Exchange (ETDEWEB)

    Scapin, Marcos A.; Guilhen, Sabine N.; Cotrim, Marycel E.B.; Pires, Maria Ap. F., E-mail: mascapin@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Hydroxyapatite (HA) is a mineral composed of calcium phosphate employed for endodontics, restorative dentistry and other applications in orthopedics and prosthesis. Additionally, this biomaterial is an inexpensive but efficient adsorbent for the removal of heavy metals and other unwanted species of contaminated liquid effluents. This is especially interesting when low-cost effective remediation is required. A Ca / P molar ratio of 1.667 is consistent with the theoretical Ca / P ratio for calcium hydroxyapatite with a compositional formula of Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, which properties are well discussed in the literature. The aim of this work was to implement and validate a methodology for simultaneous determination of major and minor constituents in the hydroxyapatite (HA) as well as providing the Ca / P molar ratio. To accomplish these achievements, wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) was applied. This is a non-destructive technique that requires no chemical treatment, enabling fast chemical analysis in a wide variety of samples, with no hazardous waste being generated as a result of the process of determination. A standard reference material from NIST (SRM 1400 – Bone Ash) was used to validate the methodology for the determination of magnesium, phosphorus, potassium, calcium, iron, zinc, strontium and the Ca / P ratio in HA samples by WDXRF. The Z-score test was applied as a statistical tool and showed that the calculated values were of less than 1.8 for all the measured analytes. (author)

  18. Adsorption and bioactivity studies of albumin onto hydroxyapatite surface.

    Science.gov (United States)

    Mavropoulos, Elena; Costa, Andréa M; Costa, Lilian T; Achete, Carlos A; Mello, Alexandre; Granjeiro, José M; Rossi, Alexandre M

    2011-03-01

    Bovine serum albumin (BSA) may have an inhibitory or promoter effect on hydroxyapatite (HA) nucleation when apatite is precipitated in a medium containing the protein. In this study we evaluated the influence of BSA on the precipitation of calcium phosphate phases (CP) from simulated body fluid (SBF) when the protein was previously bounded to HA surface. The kinetics of BSA immobilization onto hydroxyapatite surface was performed in different buffers and protein concentrations in order to adjust experimental conditions in which BSA was tightly linked to HA surface for long periods in SBF solution. It was shown that for BSA concentration higher than 0.1mg/mL the adsorption to HA surface followed Langmuir-Freundlich mechanisms, which confirmed the existence of cooperative protein-protein interactions on HA surface. Fourier Transformed Infrared Attenuated Total Reflectance Microscopy (FTIRM-ATR) evidenced changes in BSA conformational state in favor of less-ordered structure. Analyses from high resolution grazing incident X-ray diffraction using synchrotron radiation (GIXRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed that a poorly crystalline calcium phosphate was precipitated on the surface of HA discs coated with BSA, after the immersion in SBF for 4 days. The new bioactive layer had morphological characteristics similar to the one formed on the HA surface without protein. It was identified as a carbonated apatite with preferential crystal growth along apatite 002 direction. The GIXRD results also revealed that BSA layer bound to the surface inhibited the HA dissolution leading to a reduction on the formation of new calcium phosphate phase. 2010 Elsevier B.V. All rights reserved.

  19. Calcium phosphate biomaterials from marine algae. Hydrothermal synthesis and characterisation

    Directory of Open Access Journals (Sweden)

    G. Felício-Fernandes

    2000-08-01

    Full Text Available Calcium phosphate compounds such as Hydroxyapatite (HAp were prepared by hydrothermal synthesis with phycogenic CaCO3 as starting material. Material obtained was characterised by usual methods (XRD, FTIR, TG, N2-adsorption, SEM and EDX in order to study its physical-chemical characteristics. The prepared HAp showed that it may be suitable for use as a biomaterial.

  20. The comparison study of bioactivity between composites containing synthetic non-substituted and carbonate-substituted hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Borkowski, Leszek, E-mail: leszek.borkowski@umlub.pl [Chair and Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Sroka-Bartnicka, Anna [Department of Biopharmacy, Medical University of Lublin, Chodźki 4a, 20-093 Lublin (Poland); Drączkowski, Piotr [Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Medical University of Lublin, Chodźki 4a, 20-093 Lublin (Poland); Ptak, Agnieszka [Chair and Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Zięba, Emil [SEM Laboratory, Department of Zoology and Ecology, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin (Poland); Ślósarczyk, Anna [Faculty of Materials Science and Ceramics, AGH-University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland); Ginalska, Grażyna [Chair and Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland)

    2016-05-01

    Apatite forming ability of hydroxyapatite (HAP) and carbonate hydroxyapatite (CHAP) containing composites was compared. Two composite materials, intended for filling bone defects, were made of polysaccharide polymer and one of two types of hydroxyapatite. The bioactivity of the composites was evaluated in vitro by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by scanning electron microscopy with energy-dispersive spectrometer and Raman spectroscopy. The results showed that both the composites induced the formation of apatite layer on their surface after soaking in SBF. In addition, the sample weight changes and the ion concentration of the SBF were scrutinized. The results showed the weight increase for both materials after SBF treatment, higher weight gain and higher uptake of calcium ions by HAP containing scaffolds. SBF solution analysis indicated loss of calcium and phosphorus ions during experiment. All these results indicate apatite forming ability of both biomaterials and suggest comparable bioactive properties of composite containing pure hydroxyapatite and carbonate-substituted one. - Highlights: • Bioactivity of two calcium phosphates (HAP and CHAP) was compared. • Two novel ceramic-polymer composite materials were developed. • We examined apatite forming ability of scaffolds in SBF solution. • We report comparable bioactive properties between both materials.

  1. Synthesis of nanocrystalline fluorinated hydroxyapatite by ...

    Indian Academy of Sciences (India)

    Synthetic hydroxyapatite, (Ca10(PO4)6(OH)2, HA), is an important material used for orthopedic and dental implant applications. The biological hydroxyapatite in the human bone and tooth is of nanosize and differs in composition from the stoichiometric HA by the presence of other ions such as carbonate, magnesium, ...

  2. Muscle injuries: optimising recovery.

    Science.gov (United States)

    Järvinen, Tero A H; Järvinen, Teppo L N; Kääriäinen, Minna; Aärimaa, Ville; Vaittinen, Samuli; Kalimo, Hannu; Järvinen, Markku

    2007-04-01

    Muscle injuries are one of the most common traumas occurring in sports. Despite their clinical importance, there are only a few clinical studies on the treatment of muscle injuries. Lack of clinical studies is most probably attributable to the fact that there is not only a high heterogeneity in the severity of injuries, but also the injuries take place in different muscles, making it very demanding to carry out clinical trials. Accordingly, the current treatment principles of muscle injuries have either been derived from experimental studies or been tested empirically only. Clinically, first aid for muscle injuries follows the RICE (Rest, Ice, Compression and Elevation) principle. The objective of RICE is to stop the injury-induced bleeding into the muscle tissue and thereby minimise the extent of the injury. Clinical examination should be carried out immediately after the injury and 5-7 days after the initial trauma, at which point the severity of the injury can be assessed more reliably. At that time, a more detailed characterisation of the injury can be made using imaging diagnostic modalities (ultrasound or MRI) if desired. The treatment of injured skeletal muscle should be carried out by immediate immobilisation of the injured muscle (clinically, relative immobility/avoidance of muscle contractions). However, the duration of immobilisation should be limited to a period sufficient to produce a scar of sufficient strength to bear the forces induced by remobilisation without re-rupture and the return to activity (mobilisation) should then be started gradually within the limits of pain. Early return to activity is needed to optimise the regeneration of healing muscle and recovery of the flexibility and strength of the injured skeletal muscle to pre-injury levels. The rehabilitation programme should be built around progressive agility and trunk stabilisation exercises, as these exercises seem to yield better outcome for injured skeletal muscle than programmes based

  3. Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Jinfa, E-mail: jinfa.ming@gmail.com [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Liu, Zhi; Bie, Shiyu [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Zhang, Feng [Jiangsu Province Key Laboratory of Stem Cell Research, Medical College, Soochow University, Suzhou 215006 (China); Zuo, Baoqi, E-mail: bqzuo@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China)

    2014-04-01

    Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6 ± 20.4 nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0 wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. - Highlights: • SF fibers were firstly successfully dissolved in FA/HAp solution. • The rheological behavior of SF solution was significantly influenced by HAp contents. • SF nanofibrils were observed in FA/HAp solution with 103.6 ± 20.4 nm in diameter. • SF films prepared by FA/HAp dissolution method had higher mechanical properties.

  4. Hydroxyapatite and zirconia composites: Effect of MgO and MgF{sub 2} on the stability of phases and sinterability

    Energy Technology Data Exchange (ETDEWEB)

    Evis, Zafer [Department of Engineering Sciences, Middle East Technical University, Ankara 06531 (Turkey)], E-mail: evis@metu.edu.tr; Usta, Metin; Kutbay, Isil [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey)

    2008-07-15

    Composites of hydroxyapatite with cubic zirconia with MgO or MgF{sub 2} were pressureless sintered at temperatures from 1000 to 1300 deg. C. The reactions and transformations of phases were monitored with X-ray diffraction. For the hydroxyapatite and zirconia composites with MgO, calcium diffused from hydroxyapatite into the zirconia, and hydroxyapatite decomposed to tri-calcium phosphate at sintering temperatures higher than 1000 deg. C. Above about 1200 deg. C, CaZrO{sub 3} was formed. Composites containing the MgF{sub 2} decomposed slower than the composites with MgO which was verified by the changes in the lattice volume of the hydroxyapatite left in the composites. Fluorine ions in MgF{sub 2} diffused into hydroxyapatite which resulted in thermal stability at high sintering temperatures. Composites with MgF{sub 2} had higher hardness than those with MgO. The lowest porosity was found in a composite initially containing 10 wt% cubic zirconia and 5 wt% MgF{sub 2}.

  5. Effect of fuel characteristics on synthesis of calcium hydroxyapatite ...

    Indian Academy of Sciences (India)

    Administrator

    highly water-soluble glucose, the flame temperature (Tf) of the process as well as product characteristics could be controlled easily. The powders ... process depends strongly on nature and amount of fuel, surprisingly barring some sketchy .... adiabatic flame temperature, T0 the ignition temperature,. ΔHr the enthalpy of the ...

  6. Thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics

    CSIR Research Space (South Africa)

    Nilen, RWN

    2008-04-01

    Full Text Available , so the HA/b-TCP phase content ratio is a critical parameter to control during synthesis. Most BCP products have a b-TCP content of 40 wt% (balance HA), although Livingstone-Arinzeh et al. [6] recently reported that BCP with 80 wt% b-TCP content....424 10.429 10.439 c (A˚ ) 6.884 6.879 37.38 37.375 RIR None 1.06 None 1.25 J Mater Sci: Mater Med 123 (see Table 1), and XRD and FTIR were used to confirm its phase purity. Although under-reported, this HA synthesis technique is relatively simple...

  7. TEM turbulence optimisation in stellarators

    CERN Document Server

    Proll, J H E; Xanthopoulos, P; Lazerson, S A; Faber, B J

    2015-01-01

    With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic field, and the reduction of trapped-electron mode (TEM) turbulence is adressed in the present paper. Recent analytical and numerical findings suggest TEMs are stabilised when a large fraction of trapped particles experiences favourable bounce-averaged curvature. This is the case for example in Wendelstein 7-X [C.D. Beidler $\\textit{et al}$ Fusion Technology $\\bf{17}$, 148 (1990)] and other Helias-type stellarators. Using this knowledge, a proxy function was designed to estimate the TEM dynamics, allowing optimal configurations for TEM stability to be determined with the STELLOPT [D.A. Spong $\\textit{et al}$ Nucl. Fusion $\\bf{41}$, 711 (2001)] code without extensive turbulence simulations. A first proof-of-principle optimised equilibrium stemming from the TEM-dominated stella...

  8. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    Directory of Open Access Journals (Sweden)

    Zairin Noor

    2016-02-01

    Full Text Available Osteoporosis is characterized by lower bone mineral density (BMD and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to find an association between the bone microstructure and hydoxyapatite crystal structure in osteoporosis, in comparison to normal bone. The subjects of this study were surgery patients at the Department of Orthopedics of Ulin General Hospital in Banjarmasin and other centers. Inclusion criteria consisted of the presence of fracture of trabecular bone, normal or osteoporotic BMD values, and no past history of chronic disease. Bone was obtained from fracture patients during surgery. The characteristics of the hydroxyapatite crystals were analyzed by X-ray diffraction (XRD and the microarchitecture by scanning electron microscopy (SEM. SEM showed degeneration of the microarchitecture of osteoporotic bone, in comparison with normal bone. On XRD there was a peak of hydoxyapatite crystals only and no other crystal phases. Diffraction patterns showed a larger crystal size in osteoporotic bone as compared to normal bone, indicating higher porosity. It may be concluded that there is a difference in crystal size and morphologic distribution of hydoxyapatite in osteoporotic bone, determining bone microarchitecture.

  9. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    Directory of Open Access Journals (Sweden)

    Zairin Noor

    2011-04-01

    Full Text Available Osteoporosis is characterized by lower bone mineral density (BMD and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to find an association between the bone microstructure and hydoxyapatite crystal structure in osteoporosis, in comparison to normal bone. The subjects of this study were surgery patients at the Department of Orthopedics of Ulin General Hospital in Banjarmasin and other centers. Inclusion criteria consisted of the presence of fracture of trabecular bone, normal or osteoporotic BMD values, and no past history of chronic disease. Bone was obtained from fracture patients during surgery. The characteristics of the hydroxyapatite crystals were analyzed by X-ray diffraction (XRD and the microarchitecture by scanning electron microscopy (SEM. SEM showed degeneration of the microarchitecture of osteoporotic bone, in comparison with normal bone. On XRD there was a peak of hydoxyapatite crystals only and no other crystal phases. Diffraction patterns showed a larger crystal size in osteoporotic bone as compared to normal bone, indicating higher porosity. It may be concluded that there is a difference in crystal size and morphologic distribution of hydoxyapatite in osteoporotic bone, determining bone microarchitecture.

  10. Molecular Recognition at the Protein-Hydroxyapatite Interface

    Energy Technology Data Exchange (ETDEWEB)

    Stayton, Partick S.; Drobny, G. P.; Shaw, Wendy J.; Long, Joanna R.; Gilbert, Michelle R.

    2003-09-01

    Proteins found in mineralized tissues act as nature's crystal engineers, where they play a key role in promoting or inhibiting the growth of minerals, such as hydroxyapitite (bones/teeth) and calcium oxalate (kidney stones). Despite their importance in hard-tissue formation and remodeling, and in pathological processes such as stone formation and arterial calcification, there is little known of the protein structure-function relationships that govern hard-tissue engineering. Here we review early studies that have utilized solid-state NMR (ssNMR) techniques to provide in situ secondary-structure determination of statherin and statherin peptides on their biologically relevant hydroxyapatite (HAP) surfaces. In addition to direct structural study, molecular dynamics studies have provided considerable insight into the protein-binding footprint on hydroxyapatite. The molecular insight provided by these studies has also led to the design of biomimetic fusion peptides that utilize nature's crystal-recognition mechanism to display accessible and dynamic bioactive sequences from the HAP surface. These peptides selectively engage adhesion receptors and direct specific outside-in signaling pathway activation in osteoblast-like cells.

  11. Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates.

    Science.gov (United States)

    Chaudhry, Aqif A; Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

    2013-09-01

    A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO₃-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO₃-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO₃-HA. For silicate-substituted hydroxyapatite (SiO₄-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO₄-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy.

  12. Selenium-substituted hydroxyapatite nanoparticles and their in vivo antitumor effect on hepatocellular carcinoma.

    Science.gov (United States)

    Yanhua, Wang; Hao, Hang; Li, Yan; Zhang, Shengmin

    2016-04-01

    Absence of curative treatment creates urgent need for new strategies for unresectable hepatoma. Novel selenium-substituted hydroxyapatite nanoparticles (SeHAN) were designed to serve as anticancer agent. The authors examined the nanoparticles by physicochemical techniques. The in vivo efficacy and toxicity of these nanoparticles were also investigated on a nude mice model of human hepatocellular carcinoma. The results showed that the selenite ions can be incorporated into the hydroxyapatite lattice facilely. They exhibited bundles of needles shape with a size of 160-200 nm. In the in vivo study, they showed better survival advantage. The overall survival rate of nude mice in the control, pure hydroxyapatite and SeHAN group were 50.00%, 76.92%, and 100.00% respectively. Blood biochemical studies showed that SeHAN group had significantly lower toxicities on the liver and kidney functions. Histopathological studies confirmed that massive tumor necrosis and calcium deposition were evident after SeHAN treatment. Moreover, immunohistochemistry and Western blot assay showed significantly reduced expression of the Ki-67, VEGF and MMP-9 protein in the SeHAN group. Taken together, these results suggest that the selenium-substituted hydroxyapatite nanoparticles could be a new type of promising anticancer agent to provide both survival advantage and lower toxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. optimisation of solid optimisation of solid state fermentation

    African Journals Online (AJOL)

    eobe

    Ebewele3. 1,2,3 DEPARTMENT OF CHEMICAL ENGINEERING, UNIVERSITY OF BENIN, PMB 1154, BENIN CITY, EDO STATE, NIGERIA. ... the chosen independent variables and to optimise the production of citric acid using RSM. The model was .... value of the independent variable at the center point and ΔXi is the step ...

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

    Science.gov (United States)

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

    2014-04-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  16. Incorporation of 140-lanthanum into bones, teeth and hydroxyapatite.

    Science.gov (United States)

    Fernandez-Gavarron, F; Huque, T; Rabinowitz, J L; Brand, J G

    1988-03-01

    The incorporation of lanthanum in the form of 140-lanthanum onto the surface of teeth, bone and synthetic hydroxyapatite was investigated. A small amount of lanthanum was taken up by the surface of all of the materials studied regardless of their origin. The depth of penetration into bone and teeth was dependent upon lanthanum concentration and time of incubation and, in these experiments, ranged from an estimated 5 to 15 microns. An exchange of lanthanum for calcium in the apatite matrix may be responsible for increased resistance of the hard tissues to acid dissolution. The effects of pH, temperature, time and concentration of the lanthanum solutions on this incorporation were investigated. Possible clinical uses of this effect are discussed.

  17. Adsorption of low-molecular-weight sodium polyacrylate on hydroxyapatite.

    Science.gov (United States)

    Misra, D N

    1993-10-01

    Adsorption of low-molecular-weight sodium polyacrylate from aqueous solution onto synthetic hydroxyapatite was studied at room temperature so that the mechanism of adhesion of polyacrylate cements to tooth mineral could be elucidated. The adsorption isotherm of sodium polyacrylate was Langmuirian in shape and was thus qualitatively different from that of polyacrylic acid (Misra, 1991), which exhibited an adsorption maximum. The self-association of the molecules that probably causes the maximum to occur with polyacrylic acid was effectively absent for the relatively well-ionized, electrostatically repelling polyacrylate ions of the salt. With the adsorption of acrylate ions, the concentration of phosphate ions increased monotonically, while the concentration of calcium ions showed a minimum. The adsorption of sodium polyacrylate was irreversible, as it was for polyacrylic acid.

  18. Preparation of nanometer-scale rod array of hydroxyapatite crystal.

    Science.gov (United States)

    Hayakawa, Satoshi; Li, Yaqi; Tsuru, Kanji; Osaka, Akiyoshi; Fujii, Eiji; Kawabata, Koji

    2009-07-01

    Fabrication of nano- or micro-structured scaffolds to mimic structural and three-dimensional details of natural bone or teeth has been the subject of much interest, and this study proposes a new strategy for self-assembling one-dimensional hydroxyapatite (HAp) nanorods into organized superstructures. A nanometer-scale rod array of HAp having preferred orientation to the c-axis was successfully prepared simply by soaking calcium-containing silicate glass substrates in Na(2)HPO(4) aqueous solution at 80 degrees C for various periods. Those HAp rods grew perpendicularly to the glass surface, and the crystallites covered the glass surface uniformly, resulting in a "dental enamel-like" rod array structure consisting of "pine-leaf-like" structure units.

  19. Thermal effects of carbonated hydroxyapatite modified by glycine and albumin

    Science.gov (United States)

    Gerk, S. A.; Golovanova, O. A.; Kuimova, M. V.

    2017-01-01

    In this work calcium phosphate powders were obtained by precipitation method from simulated solutions of synovial fluid containing glycine and albumin. X-ray diffraction and IR spectroscopy determined that all samples are single-phase and are presented by carbonate containing hydroxyapatite (CHA). The thermograms of solid phases of CHA were obtained and analyzed; five stages of transformation in the temperature range of 25-1000°C were marked. It is shown that in this temperature range dehydration, decarboxylation and thermal degradation of amino acid and protein connected to the surface of solid phase occur. The tendency of temperature lowering of the decomposition of powders synthesized from a medium containing organic substances was determined. Results demonstrate a direct dependence between the concentration of the amino acid in a model solution and its content in the solid phase.

  20. Thin hydroxyapatite surface layers on titanium produced by ion implantation

    CERN Document Server

    Baumann, H; Bilger, G; Jones, D; Symietz, I

    2002-01-01

    In medicine metallic implants are widely used as hip replacement protheses or artificial teeth. The biocompatibility is in all cases the most important requirement. Hydroxyapatite (HAp) is frequently used as coating on metallic implants because of its high acceptance by the human body. In this paper a process is described by which a HAp surface layer is produced by ion implantation with a continuous transition to the bulk material. Calcium and phosphorus ions are successively implanted into titanium under different vacuum conditions by backfilling oxygen into the implantation chamber. Afterwards the implanted samples are thermally treated. The elemental composition inside the implanted region was determined by nuclear analysis methods as (alpha,alpha) backscattering and the resonant nuclear reaction sup 1 H( sup 1 sup 5 N,alpha gamma) sup 1 sup 2 C. The results of X-ray photoelectron spectroscopy indicate the formation of HAp. In addition a first biocompatibility test was performed to compare the growing of m...

  1. Interactive distributed optimisation for multidisciplinary design

    NARCIS (Netherlands)

    Jansen, J.D.; Rolvink, A.; Coenders, J.L.; Schevenels, M.

    2014-01-01

    This paper presents the development of a multidisciplinary optimisation system for the Architecture Engineering and Construction (AEC) industry. The system consists of two major components, namely a multidisciplinary optimisation framework and a distributed cloud-based analysis framework. The former

  2. Substituted Hydroxyapatites with Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Joanna Kolmas

    2014-01-01

    Full Text Available 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.

  3. Can mesenchymal stem cell survive in hydroxyapatite sulphate?

    Directory of Open Access Journals (Sweden)

    Erica Kholinne

    2012-02-01

    Full Text Available Background: Many studies have reported the role of Mesenchymal Stem Cells (MSC in treating fractures. In case with bone defect, fracture healing needs not only osteogenic but also osteoconductive component (scaffold. Hydroxyapatite calcium sulphate (HA-CaSO4 being widely used as bone void filler, may serve as scaffold for MSC. However, the effect of this scaffold to the viability of MSC has not been evaluated before.Methods: MSC were isolated from the iliac marrow of a Giant Flamish rabbit, and expanded in DMEM using histogradient density. After one week, they were sub-cultured in a 25cc TC flask (passage 1 and have the medium replaced every 3 days. During the subculture, we embedded a HA-CaSO4 pellet into the flask. The cells were evaluated under inverted microscope at a weekly interval.Results: At the first week, MSC are difficult to be identified in microscope due to the large number of HA-CaSO4 crystals. By the third week however MSC have grown and the HA-CaSO4 crystals can readily be washed off by medium replacement. By the fourth weeks, MSC can be still seen on microscope.Conclusion: HA-CaSO4 could serve as a good scaffold due to its pellet shape and easily absorbed, thus providing revascularization which is essential for bone healing.In addition, HA-CaSO4 does not interfere with MSC survival. (Med J Indones 2012;21:8-12Keywords: Fracture healing, Hydroxyapatite Calcium Sulphate (HA-CaSO4, Mesenchymal Stem Cells (MSC

  4. Computational optimisation of robust sheet forming processes

    NARCIS (Netherlands)

    van den Boogaard, Antonius H.; Tisza, M.; Bonte, M.H.A.; van Ravenswaaij, R.

    2007-01-01

    Mathematical optimisation consists of the modelling and solving of optimisation problems. Although both the modelling and the solving are essential for successfully optimising metal forming problems, much of the research published until now has focussed on the solving part, i.e. the development of a

  5. Foamed surfactant solution as a template for self-setting injectable hydroxyapatite scaffolds for bone regeneration.

    Science.gov (United States)

    Montufar, E B; Traykova, T; Gil, C; Harr, I; Almirall, A; Aguirre, A; Engel, E; Planell, J A; Ginebra, M P

    2010-03-01

    The application of minimally invasive surgical techniques in the field of orthopaedic surgery has created a growing need for new injectable synthetic materials that can be used for bone grafting. In this work a novel fully synthetic injectable calcium phosphate foam was developed by mixing alpha-tricalcium phosphate (alpha-TCP) powder with a foamed polysorbate 80 solution. Polysorbate 80 is a non-ionic surfactant approved for parenteral applications. The foam was able to retain the porous structure after injection provided that the foamed paste was injected shortly after mixing (typically 2.5 min), and set through the hydrolysis of alpha-TCP to a calcium-deficient hydroxyapatite, thus producing a hydroxyapatite solid foam in situ. The effect of different processing parameters on the porosity, microstructure, injectability and mechanical properties of the hydroxyapatite foams was analysed, and the ability of the pre-set foam to support osteoblastic-like cell proliferation and differentiation was assessed. Interestingly, the concentration of surfactant needed to obtain the foams was lower than that considered safe in drug formulations for parenteral administration. The possibility of combining bioactivity, injectability, macroporosity and self-setting ability in a single fully synthetic material represents a step forward in the design of new materials for bone regeneration compatible with minimally invasive surgical techniques. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Modulation of enamel matrix proteins on the formation and nano-assembly of hydroxyapatite in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Li Hong, E-mail: tlihong@jnu.edu.cn [Department of Materials Science and Engineering, Jinan University, Guangzhou, Guangdong 510630 (China); Department of Bioengineering, Clemson University, Charleston, SC 29425 (United States); Huang Weiya [Department of Chemistry, Jinan University, Guangzhou, Guangdong 510630 (China); Department of Materials Science and Engineering, Taizhou, Taizhou University, Zhejiang 317000 (China); Zhang Yuanming [Department of Chemistry, Jinan University, Guangzhou, Guangdong 510630 (China); Xue Bo [Department of Materials Science and Engineering, Jinan University, Guangzhou, Guangdong 510630 (China); Wen Xuejun [Department of Bioengineering, Clemson University, Charleston, SC 29425 (United States)

    2012-05-01

    Natural enamel has a hierarchically nanoassembled architecture that is regulated by enamel matrix proteins (EMPs) during the formation of enamel crystals. To understand the role of EMPs on enamel mineralization, calcium phosphate (CaP) growth experiments in both the presence and absence of native rat EMPs in a single diffusion system were conducted. The morphology and organization of formed CaP crystals were examined by X-Ray Diffraction (XRD), High-Resolution Transmission Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). In the system containing the EMPs, hydroxyapatite (HAP) with hierarchical lamellar nanostructure can be formed and the aligned HAP assembly tightly bundled by 3-4 rod-like nanocrystals like an enamel prism. However, in the absence of EMPs, only a sheet-like structure of octacalcium phosphate (OCP) phase was presented. EMPs promote HAP formation and inhibit the growth of OCP on the (010) plane. It is discussed that the organized Amelogenin/Amorphous Calcium Phosphate might be the precursor to the bundled HAP crystal prism. The study benefits the understanding of biomineralization of tooth enamel. - Highlights: Black-Right-Pointing-Pointer An aligned hydroxyapatite crystal bundled by rod-like nanosize crystals was obtained. Black-Right-Pointing-Pointer An organized Amel/ACP would be the precursor of the bundled hydroxyapatite crystal prism. Black-Right-Pointing-Pointer EMPs inhibit the growth of octacalcium phosphate in a defined plane.

  7. Cogeneration technologies, optimisation and implementation

    CERN Document Server

    Frangopoulos, Christos A

    2017-01-01

    Cogeneration refers to the use of a power station to deliver two or more useful forms of energy, for example, to generate electricity and heat at the same time. This book provides an integrated treatment of cogeneration, including a tour of the available technologies and their features, and how these systems can be analysed and optimised.

  8. For Time-Continuous Optimisation

    DEFF Research Database (Denmark)

    Heinrich, Mary Katherine; Ayres, Phil

    2016-01-01

    Strategies for optimisation in design normatively assume an artefact end-point, disallowing continuous architecture that engages living systems, dynamic behaviour, and complex systems. In our Flora Robotica investigations of symbiotic plant-robot bio-hybrids, we re- quire computational tools...

  9. Wheel/rail interface optimisation

    NARCIS (Netherlands)

    Shevtsov, I.Y.

    2008-01-01

    In this thesis, wheel/rail interface optimisation, and particularly the problems of wheel and rail profile design are considered. The research task pursued by this thesis engenders investigation of a range of problems. First, geometric properties of contact between wheel and rail are investigated.

  10. Tissue reaction and material biodegradation of a calcium sulfate/apatite biphasic bone substitute in rat muscle

    Directory of Open Access Journals (Sweden)

    Jian-Sheng Wang

    2016-07-01

    Conclusion: Calcium sulfate hydroxyapatite bone substitute can be used as a carrier for antibiotics or other drugs, without adverse reaction due to the fast resorption of the calcium sulfate. No bone formation was seen despite treating the bone substitute with autologous bone marrow.

  11. Novel soybean/gelatine-based bioactive and injectable hydroxyapatite foam: material properties and cell response.

    Science.gov (United States)

    Perut, F; Montufar, E B; Ciapetti, G; Santin, M; Salvage, J; Traykova, T; Planell, J A; Ginebra, M P; Baldini, N

    2011-04-01

    Despite their known osteoconductivity, clinical use of calcium phosphate cements is limited both by their relatively slow rate of resorption and by rheological properties incompatible with injectability. Bone in-growth and material resorption have been improved by the development of porous calcium phosphate cements. However, injectable formulations have so far only been obtained through the addition of relatively toxic surfactants. The present work describes the response of osteoblasts to a novel injectable foamed bone cement based on a composite formulation including the bioactive foaming agents soybean and gelatine. The foaming properties of both defatted soybean and gelatine gels were exploited to develop a self-hardening soy/gelatine/hydroxyapatite composite foam able to retain porosity upon injection. After setting, the foamed paste produced a calcium-deficient hydroxyapatite scaffold, showing good injectability and cohesion as well as interconnected porosity after injection. The intrinsic bioactivity of soybean and gelatine was shown to favour osteoblast adhesion and growth. These findings suggest that injectable, porous and bioactive calcium phosphate cements can be produced for bone regeneration through minimally invasive surgery. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Bovine serum albumin conformational changes upon adsorption on titania and on hydroxyapatite and their relation with biomineralization.

    Science.gov (United States)

    Serro, A P; Bastos, M; Pessoa, J Costa; Saramago, B

    2004-09-01

    The biocompatibility of implant materials used for substitution of bone tissue depends on its ability to induce the deposition of a hydroxyapatite layer when in contact with body fluids. In previous work, some of the authors found that bovine serum albumin (BSA) promotes calcium phosphate deposition if preadsorbed on hydroxyapatite and retards precipitation if preadsorbed on titania. In the present study, we investigated the adsorption of BSA upon particles of titania and hydroxyapatite in order to understand the different role played by the protein on the mineralization of both biomaterials. The adsorption isotherms were determined and the structural changes induced by adsorption at different surface coverages were investigated by circular dichroism spectroscopy and differential scanning microcalorimetry. At low surface coverages, the adsorbed BSA molecules lost part of their alpha-helix content. However, at high surface coverages, corresponding to the plateau values of the adsorption isotherms, the BSA molecules did not undergo structural rearrangements upon adsorption. In the latter circumstances, the availability of BSA calcium binding sites, which should be responsible for inducing mineralization, depends on the electrostatic interactions between BSA and the sorbent surface. A possible explanation for the different mineralization behavior of hydroxyapatite and titania is advanced. Copyright 2004 Wiley Periodicals, Inc.

  13. The comparison study of bioactivity between composites containing synthetic non-substituted and carbonate-substituted hydroxyapatite.

    Science.gov (United States)

    Borkowski, Leszek; Sroka-Bartnicka, Anna; Drączkowski, Piotr; Ptak, Agnieszka; Zięba, Emil; Ślósarczyk, Anna; Ginalska, Grażyna

    2016-05-01

    Apatite forming ability of hydroxyapatite (HAP) and carbonate hydroxyapatite (CHAP) containing composites was compared. Two composite materials, intended for filling bone defects, were made of polysaccharide polymer and one of two types of hydroxyapatite. The bioactivity of the composites was evaluated in vitro by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by scanning electron microscopy with energy-dispersive spectrometer and Raman spectroscopy. The results showed that both the composites induced the formation of apatite layer on their surface after soaking in SBF. In addition, the sample weight changes and the ion concentration of the SBF were scrutinized. The results showed the weight increase for both materials after SBF treatment, higher weight gain and higher uptake of calcium ions by HAP containing scaffolds. SBF solution analysis indicated loss of calcium and phosphorus ions during experiment. All these results indicate apatite forming ability of both biomaterials and suggest comparable bioactive properties of composite containing pure hydroxyapatite and carbonate-substituted one. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Study of mixed Ca-Zn hydroxyapatite surface modified by lactic acid

    Science.gov (United States)

    Turki, Thouraya; Aissa, Abdallah; Bac, Christophe Goze; Rachdi, Férid; Debbabi, Mongi

    2012-07-01

    The new hybrid inorganic-organic composites, Ca(10-x)Znx(PO4)6(OH)2-lactic acid, at different amounts of zinc and lactic acid were prepared by dissolution of the organic compound in an hydroxyapatite suspension. They were characterized by XRD, IR, MAS NMR (13C and 1H) and chemical analysis. The crystallinity was slightly affected by the presence of organic fragments. IR and (13C and 1H) MAS NMR measurements indicate that the carboxylic groups of the acid interact with calcium and zinc ions of hydroxyapatite surface. Chemical analysis displays that zinc promotes the acid grafting. A mechanism of surface modification is proposed based on the obtained results.

  15. Nanocomposite materials based on hydroxyapatite and sodium alginate: synthesis and characteristics

    Directory of Open Access Journals (Sweden)

    О. О. Мартинюк

    2015-10-01

    Full Text Available This work is devoted to the development and optimization of the synthesis methodof nanostructured biopolymer-apatite composite materials for medical applications with different ratios of polymer (sodium alginate, SA and inorganic (hydroxyapatite, HA phases and research their properties. Composition, structure and morphology of the samples by FTIR spectroscopy, X-ray diffraction and transmission electron microscopy (TEM were characterized. Porosity, degree of swelling and in vitro response on bioactivity in physiological solution obtained compositesweredetermined. The formation in the presence of sodium alginate hydroxyapatite phase with needle structure and average crystallite size 23 nm with simultaneous formation biopolymer matrix due to the interaction of positively charged calcium ions (Ca2+ and negatively charged carboxyl groups (COO- by instrumental methodswasconfirmed. The pH changing of physiological solution in the presence of samples testifies their bioactivit

  16. The growth process of regular radiated nanorod bundles hydroxyapatite formed by thermal aqueous solution approach

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hui; Hao, Lijing; Zhao, Naru; Huang, Miaojun [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Du, Chang, E-mail: duchang@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Wang, Yingjun, E-mail: imwangyj@163.com [National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China)

    2013-08-15

    Nanorod bundles of hydroxyapatite (nrHA) with ordered radiated structure was successfully prepared through hydrothermal treatment, with the hexadecyltrimethylammonium bromide (CTAB) and sodium citrate as surfactant and crystal modifier, respectively. The results showed that the citrate and CTAB played an important role in assembly of nanorods. Moreover, the pH value of the original solution also can influence the final morphology of products. The possible formation mechanism of nanorod bundle structure was discussed in detail. - Highlights: • Nanobundles of hydroxyapatite with ordered radiated structure was prepared. • CTAB regulates the nucleation and growth of crystal. • Calcium citrate modifies the formation of crystals. • Citrate promote the transformation of CTAB micelles. • Citrate causes a heteroepitaxial growth of crystals. - Graphical abstract: Display Omitted.

  17. Study of mixed Ca-Zn hydroxyapatite surface modified by lactic acid

    Energy Technology Data Exchange (ETDEWEB)

    Turki, Thouraya; Aissa, Abdallah [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia); Bac, Christophe Goze [Laboratoire Charles Coulomb, UMR 5221 CNRS/UM2, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier (France); Rachdi, Ferid, E-mail: Ferid.Rachdi@univ-montp2.fr [Laboratoire Charles Coulomb, UMR 5221 CNRS/UM2, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier (France); Debbabi, Mongi [Laboratoire de Physico-Chimie des Materiaux, Faculte des Sciences de Monastir, 5019 Monastir (Tunisia)

    2012-07-01

    The new hybrid inorganic-organic composites, Ca{sub (10-x)}Zn{sub x}(PO{sub 4}){sub 6}(OH){sub 2}-lactic acid, at different amounts of zinc and lactic acid were prepared by dissolution of the organic compound in an hydroxyapatite suspension. They were characterized by XRD, IR, MAS NMR ({sup 13}C and {sup 1}H) and chemical analysis. The crystallinity was slightly affected by the presence of organic fragments. IR and ({sup 13}C and {sup 1}H) MAS NMR measurements indicate that the carboxylic groups of the acid interact with calcium and zinc ions of hydroxyapatite surface. Chemical analysis displays that zinc promotes the acid grafting. A mechanism of surface modification is proposed based on the obtained results.

  18. Effects of dietary calcium on Helicobacter pylori-induced gastritis in Mongolian gerbils.

    Science.gov (United States)

    Iimuro, Masaki; Nakamura, Shiro; Arakawa, Tetsuo; Wakabayashi, Keiji; Mutoh, Michihiro

    2013-09-01

    Helicobacter pylori (Hp) infection causes gastritis and is considered a gastric cancer risk factor. We have previously reported that codfish meal markedly enhanced Hp-induced gastritis in Mongolian gerbils. In the present study, we sought the responsible components in codfish meal. Codfish were divided into three parts (meat, viscera and 'other parts', including bone), and administered to Hp-infected gerbils. Subsequently, cod bone, sardine bone and prawn shell were tested, along with major calcium components, hydroxyapatite and calcium carbonate, in bone and shell, respectively. 'Other parts' and cod bone enhanced Hp-induced gastritis, as was observed for whole codfish. Similarly, sardine bone and prawn shell, as well as 0.22-0.88% hydroxyapatite and calcium carbonate, enhanced gastritis. In contrast, administration of a higher dose of the calcium compounds exerted protective effects. Intake of calcium compounds may contribute to enhancement of Hp-induced gastritis.

  19. 3D silicon doped hydroxyapatite scaffolds decorated with Elastin-like Recombinamers for bone regenerative medicine.

    Science.gov (United States)

    Vila, Mercedes; García, Ana; Girotti, Alessandra; Alonso, Matilde; Rodríguez-Cabello, Jose Carlos; González-Vázquez, Arlyng; Planell, Josep A; Engel, Elisabeth; Buján, Julia; García-Honduvilla, Natalio; Vallet-Regí, María

    2016-11-01

    The current study reports on the manufacturing by rapid prototyping technique of three-dimensional (3D) scaffolds based on silicon substituted hydroxyapatite with Elastin-like Recombinamers (ELRs) functionalized surfaces. Silicon doped hydroxyapatite (Si-HA), with Ca10(PO4)5.7(SiO4)0.3(OH)1.7h0.3 nominal formula, was surface functionalized with two different types of polymers designed by genetic engineering: ELR-RGD that contain cell attachment specific sequences and ELR-SNA15/RGD with both hydroxyapatite and cells domains that interact with the inorganic phase and with the cells, respectively. These hybrid materials were subjected to in vitro assays in order to clarify if the ELRs coating improved the well-known biocompatible and bone regeneration properties of calcium phosphates materials. The in vitro tests showed that there was a total and homogeneous colonization of the 3D scaffolds by Bone marrow Mesenchymal Stromal Cells (BMSCs). In addition, the BMSCs were viable and able to proliferate and differentiate into osteoblasts. Bone tissue engineering is an area of increasing interest because its main applications are directly related to the rising life expectancy of the population, which promotes higher rates of several bone pathologies, so innovative strategies are needed for bone tissue regeneration therapies. Here we use the rapid prototyping technology to allow moulding ceramic 3D scaffolds and we use different bio-polymers for the functionalization of their surfaces in order to enhance the biological response. Combining the ceramic material (silicon doped hydroxyapatite, Si-HA) and the Elastin like Recombinamers (ELRs) polymers with the presence of the integrin-mediate adhesion domain alone or in combination with SNA15 peptide that possess high affinity for hydroxyapatite, provided an improved Bone marrow Mesenchymal Stromal Cells (BMSCs) differentiation into osteoblastic linkage. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights

  20. Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2010-07-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  1. Ostrich eggshell as an alternative raw material for hydroxyapatite synthesis; Sintese e caracterizacao de hidroxiapatita a partir da casca de ovo de avestruz

    Energy Technology Data Exchange (ETDEWEB)

    Caliman, L.B.; Gouvea, D., E-mail: orenabatistacaliman@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Metalurgica; Della, V.P. [Institutlo Federal do Espirito Santo (IFES), ES (Brazil)

    2011-07-01

    The goal of this study was to investigate the use of ostrich eggshell for hydroxyapatite synthesis, a biomaterial of great medical importance due to its high biocompatibility. The eggshell was used as calcium ions source due its great containing of CaCO3. For its utilization, the eggshell was calcined and the obtained oxide (CaO) was transformed into Ca(OH){sub 2}. Hydroxyapatite synthesis consisted in a wet precipitation reaction between Ca(OH){sub 2} and commercial H{sub 3}PO{sub 4}. The X ray Diffraction analysis has shown that the precipitated Hydroxyapatite calcined at 800°C resulted in a bifasic powder of Hydroxyapatite and β-Tricalcium Phosphate, which proves that this precipitated Hydroxyapatite was deficient in calcium. The Infrared Spectroscopy, showed the presence of CO{sub 3}{sup 2-} ions, result of carrying out the reaction in open atmosphere. By Scanning Electron Microscopy nanometric particles arranged in agglomerates were observed and Specific Surface Area measurement resulted in 11,70 m²/g. Following this procedure, the ostrich eggshell gets a technological profitable reuse also environmentally friendly, being transformed in a new product of high aggregate value. (author)

  2. Codon optimisation is key for pernisine expression in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Marko Šnajder

    Full Text Available Pernisine is an extracellular serine protease from the hyperthermophilic Archaeon Aeropyrum pernix K1. Low yields from the natural host and expression problems in heterologous hosts have limited the potential applications of pernisine in industry.The challenges of pernisine overexpression in Escherichia coli were overcome by codon preference optimisation and de-novo DNA synthesis. The following forms of the pernisine gene were cloned into the pMCSGx series of vectors and expressed in E. coli cells: wild-type (pernisinewt, codon-optimised (pernisineco, and codon-optimised with a S355A mutation of a predicted active site (pernisineS355Aco. The fusion-tagged pernisines were purified using fast protein liquid chromatography equipped with Ni2+ chelate and gel filtration chromatography columns. The identities of the resultant proteins were confirmed with N-terminal sequencing, tandem mass spectrometry analysis, and immunodetection. Pernisinewt was not expressed in E. coli at detectable levels, while pernisineco and pernisineS355Aco were expressed and purified as 55-kDa proforms with yields of around 10 mg per litre E. coli culture. After heat activation of purified pernisine, the proteolytic activity of the mature pernisineco was confirmed using zymography, at a molecular weight of 36 kDa, while the mutant pernisineS355Aco remained inactive. Enzymatic performances of pernisine evaluated under different temperatures and pHs demonstrate that the optimal enzymatic activity of the recombinant pernisine is ca. 100°C and pH 7.0, respectively.These data demonstrate that codon optimisation is crucial for pernisine overexpression in E. coli, and that the proposed catalytic Ser355 has an important role in pernisine activity, but not in its activation process. Pernisine is activated by autoproteolytical cleavage of its N-terminal proregion. We have also confirmed that the recombinant pernisine retains the characteristics of native pernisine, as a calcium

  3. Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity.

    Science.gov (United States)

    Yatongchai, Chokchai; Placek, Lana M; Curran, Declan J; Towler, Mark R; Wren, Anthony W

    2015-11-01

    Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability. © The Author(s) 2015.

  4. Synthesis and Characterization of Hydroxyapatite/Fullerenol Nanocomposites.

    Science.gov (United States)

    Djordjevic, Aleksandar; Ignjatovic, Nenad; Seke, Mariana; Jovic, Danica; Uskokovic, Dragan; Rakocevic, Zlatko

    2015-02-01

    Fullerenols are polyhydroxylated, water soluble derivatives of fullerene C60, with potential application in medicine as diagnostic agents, antioxidants or nano drug carriers. This paper describes synthesis and physical characterization of a new nanocomposite hydroxyapatite/fullerenol. Surface of the nanocomposite hydroxyapatite/fullerenol is inhomogeneous with the diameter of the particles in the range from 100 nm to 350 nm. The ζ potential of this nanocomposite is ten times lower when compared to hydroxyapatite. Surface phosphate groups of hydroxyapatite are prone to forming hydrogen bonds, when in close contact with hydroxyl groups, which could lead to formation of hydrogen bonds between hydroxyapatite and hydroxyl groups of fullerenol. The surface of hydroxyapatite particles (-2.5 mV) was modified by fullerenol particles, as confirmed by the obtained ζ potential value of the nanocomposite biomaterial hydroxyapatite/fullerenol (-25.0 mV). Keywords: Hydroxyapatite, Fullerenol, Nanocomposite, Surface Analysis.

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

    Directory of Open Access Journals (Sweden)

    Widowati Siswomihardjo

    2012-01-01

    . 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.

  6. Anisotropic diffusion of water molecules in hydroxyapatite nanopores

    Science.gov (United States)

    Prakash, Muthuramalingam; Lemaire, Thibault; Caruel, Matthieu; Lewerenz, Marius; de Leeuw, Nora H.; Di Tommaso, Devis; Naili, Salah

    2017-07-01

    New insights into the dynamical properties of water in hydroxyapatite (HAP) nanopores, a model system for the fluid flow within nanosize spaces inside the collagen-apatite structure of bone, were obtained from molecular dynamics simulations of liquid water confined between two parallel HAP surfaces of different sizes (20 Å ≤ H ≤ 240 Å). Calculations were conducted using a core-shell interatomic potential for HAP together with the extended simple point charge model for water. This force field gives an activation energy for water diffusion within HAP nanopores that is in excellent agreement with available experimental data. The dynamical properties of water within the HAP nanopores were quantified in terms of the second-order water diffusion tensor. Results indicate that water diffuses anisotropically within the HAP nanopores, with the solvent molecules moving parallel to the surface twice as fast as the perpendicular direction. This unusual dynamic behaviour is linked to the strong polarizing effect of calcium ions, and the synergic interactions between the water molecules in the first hydration layer of HAP with the calcium, hydroxyl, and phosphate ions, which facilitates the flow of water molecules in the directions parallel to the HAP surface.

  7. Transformation of brushite to hydroxyapatite and effects of alginate additives

    Science.gov (United States)

    Ucar, Seniz; Bjørnøy, Sindre H.; Bassett, David C.; Strand, Berit L.; Sikorski, Pawel; Andreassen, Jens-Petter

    2017-06-01

    Phase transformations are important processes during mineral formation in both in vivo and in vitro model systems and macromolecules are influential in regulating the mineralization processes. Calcium phosphate mineralized alginate hydrogels are potential candidates for hard tissue engineering applications and transformation of the resorbable calcium phosphate phases to apatitic bone mineral in vivo enhances the success of these composite materials. Here, the transformation of brushite to hydroxyapatite (HA) and the effects of alginate additives on this process are studied by the investigation of supersaturation profiles with HA-seeded and unseeded experiments. This experimental design allows for detailed kinetic interpretation of the transformation reactions and deduction of information on the nucleation stage of HA by evaluating the results of seeded and unseeded experiments together. In the experimental conditions of this work, transformation was controlled by HA growth until the point of near complete brushite dissolution where the growth and dissolution rates were balanced. The presence of alginate additives at low concentration were not highly influential on transformation rates during the growth dominated region but their retardant effect became more pronounced as the dissolution and growth rates reached an equilibrium where both reactions were effective on transformation kinetics. Decoupling of seeded and unseeded transformation experiments suggested that alginate additives retard HA nucleation and this was most evident in the presence of G-block oligomers.

  8. Synthesis and characterization of hydroxyapatite from fish bone waste

    Science.gov (United States)

    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.

  9. Synthesis and characterization of hydroxyapatite from fish bone waste

    Energy Technology Data Exchange (ETDEWEB)

    Marliana, Ana, E-mail: na-cwith22@yahoo.co.id; Fitriani, Eka; Ramadhan, Fauzan; Suhandono, Steven; Yuliani, Keti; Windarti, Tri [Chemistry Department, Faculty of Science and Mathematics, Diponegoro University, Indonesia, 50 275 (Indonesia)

    2015-12-29

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

  10. Characteristics of porous zirconia coated with hydroxyapatite as ...

    Indian Academy of Sciences (India)

    Since hydroxyapatite has excellent biocompatibility and bone bonding ability, porous hydroxyapatite ceramics have been intensively studied. However, porous hydroxyapatite bodies are mechanically weak and brittle, which makes shaping and implantation difficult. One way to solve this problem is to introduce a strong ...

  11. Laser-Raman Spectroscopic study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel.

    Science.gov (United States)

    Ozaki, M; Suzuki, M; Itoh, K; Wakumoto, S

    1991-12-01

    The possible chemical interaction between synthetic hydroxyapatite or bovine enamel and a functional monomer of 4-methacryloxyethyl trimellitic acid (4-MET) diluted in methyl methacrylate (MMA) was examined by measuring the Raman spectra. It was concluded that the carboxyl group of 4-MET reacted with the calcium in the substrate to form a salt that was detected by the Raman band at around 1,380 cm-1. However, formation of the salt on the surface of the hydroxyapatite (HAP) with the carboxyl group, and polymerization of the 4-MET in the methacryl group near the surface were mutually exclusive reactions for the same 4-MET molecule.

  12. Dose optimisation in single plane interstitial brachytherapy.

    Science.gov (United States)

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette Benedicte; Nielsen, Søren Kynde; Olsen, Dag Rune; Grau, Cai; Lindegaard, Jacob Christian

    2006-10-01

    Brachytherapy dose distributions can be optimised by modulation of source dwell times. In this study dose optimisation in single planar interstitial implants was evaluated in order to quantify the potential benefit in patients. In 14 patients, treated for recurrent rectal and cervical cancer, flexible catheters were sutured intra-operatively to the tumour bed in areas with compromised surgical margin. Both non-optimised, geometrically and graphically optimised CT -based dose plans were made. The overdose index (OI), homogeneity index (HI), conformal index (COIN), minimum target dose, and high dose volumes were evaluated. The dependence of OI, HI, and COIN on target volume and implant regularity was evaluated. In addition, 12 theoretical implant configurations were analyzed. Geometrical and graphical optimisation improved the dose plans significantly with graphical optimisation being superior. Graphically optimised dose plans showed a significant decrease of 18%+/-9% in high dose volume (p<0.001). HI, COIN, and OI were significantly improved from 0.50+/-0.05 to 0.60+/-0.05, from 0.65+/-0.04 to 0.71+/-0.04, and from 0.19+/-0.03 to 0.15+/-0.03, respectively (p<0.001 for all). Moreover, minimum target dose increased significantly from 71%+/-5% to 80%+/-5% (p<0.001). The improvement in OI and HI obtained by optimisation depended on the regularity of the implant, such that the benefit of optimisation was larger for irregular implants. OI and HI correlated strongly with target volume limiting the usability of these parameters for comparison of dose plans between patients. Dwell time optimisation significantly improved the dose distribution regarding homogeneity, conformity, minimum target dose, and size of high dose volumes. Graphical optimisation is fast, reproducible and superior to geometric optimisation.

  13. An Optimisation Approach for Room Acoustics Design

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Kirkegaard, Poul Henning; Andersen, Lars

    2005-01-01

    This paper discuss on a conceptual level the value of optimisation techniques in architectural acoustics room design from a practical point of view. It is chosen to optimise one objective room acoustics design criterium estimated from the sound field inside the room. The sound field is modeled...... using the boundary element method where absorption is incorporated. An example is given where the geometry of a room is defined by four design modes. The room geometry is optimised to get a uniform sound pressure....

  14. The effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate bone cement

    Science.gov (United States)

    Razali, N. N.; Sukardi, M. A.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

    2018-01-01

    The objective of this study is to determine the effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate cement (CPC) for bone filling applications. Hydroxyapatite powder was synthesized via hydrothermal method using calcium oxide, CaO and ammonium dihydrogen phosphate, NH4H2PO4 as the calcium and phosphorus precursors respectively. The effects of calcium excess were evaluated by varying the CaO content at 0, 5 and 15 mole %. The precursors were then refluxed in distilled water at 90-100°C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the synthesized powder with distilled water at the powder-to-liquid (P/L) ratio of 1.5. The result from the morphological properties of CPC shows the increase in agglomeration and particles size with 5 mole % of calcium excess but decreased with 15 mole % of calcium excess in CPC. This result was in agreement with the compressive strength result where the CPC increased its strength with 5 mole % of calcium excess but reduced with 15 mole % of calcium excess. The excess in calcium precursor also significantly improved the setting time but reduced the injectability of CPC.

  15. Influence of process conditions on hydroxyapatite crystallinity obtained by direct crystallization

    Directory of Open Access Journals (Sweden)

    Seckler M.M.

    1999-01-01

    Full Text Available Crystallization from solutions was applied to produce stoichiometric and crystalline hydroxyapatite (HAP suitable for use as a biomaterial. This was accomplished by keeping a low supersaturation through the following procedure: semi-continuous operating mode, slow reactant addition rate and addition of a calcium complexing agent. A high temperature (90 °C and probably carbonate incorporation also favored the formation of a well crystallized material. A qualitative correlation was found between the supersaturation and HAP properties such as crystallinity and particle size.

  16. Spontaneous loosening of hydroxyapatite peg sleeves.

    Science.gov (United States)

    Jordan, D R

    2001-11-01

    To report a new complication associated with pegging hydroxyapatite orbital implants: spontaneous loosening of the sleeve. Retrospective noncomparative case series. Four patients ranging in age from 38 to 60 years participated. Four patients are described who successfully received hydroxyapatite orbital implants with motility peg and sleeve systems. In each case spontaneous loosening of the sleeve developed. Clinical and surgical outcomes were assessed. Three patients had the peg and sleeve removed followed by repair of the peg hole, and one patient had placement of a larger diameter peg and sleeve system. All patients did well. Problems have been reported when motility coupling pegs are used with hydroxyapatite orbital implants. Spontaneous loosening of the sleeve is another potential complication to discuss with the patient considering an implant peg.

  17. Optimisation combinatoire Theorie et algorithmes

    CERN Document Server

    Korte, Bernhard; Fonlupt, Jean

    2010-01-01

    Ce livre est la traduction fran aise de la quatri me et derni re dition de Combinatorial Optimization: Theory and Algorithms crit par deux minents sp cialistes du domaine: Bernhard Korte et Jens Vygen de l'universit de Bonn en Allemagne. Il met l accent sur les aspects th oriques de l'optimisation combinatoire ainsi que sur les algorithmes efficaces et exacts de r solution de probl mes. Il se distingue en cela des approches heuristiques plus simples et souvent d crites par ailleurs. L ouvrage contient de nombreuses d monstrations, concises et l gantes, de r sultats difficiles. Destin aux tudia

  18. TSDC and impedance spectroscopy measurements on hydroxyapatite, β-tricalcium phosphate and hydroxyapatite/β-tricalcium phosphate biphasic bioceramics

    Science.gov (United States)

    Prezas, P. R.; Melo, B. M. G.; Costa, L. C.; Valente, M. A.; Lança, M. C.; Ventura, J. M. G.; Pinto, L. F. V.; Graça, M. P. F.

    2017-12-01

    Bone grafting and surgical interventions related with orthopaedic disorders consist in a big business, generating large revenues worldwide every year. There is a need to replace the biomaterials that currently still dominate this market, i.e., autografts and allografts, due to their disadvantages, such as limited availability, need for additional surgeries and diseases transmission possibilities. The most promising replacement materials are biomaterials with bioactive properties, such as the calcium phosphate-based bioceramics group. The bioactivity of these materials, i.e., the rate at which they promote the growth and directly bond with the new host biological bone, can be enhanced through their electrical polarization. In the present work, the electrical polarization features of pure hydroxyapatite (Hap), pure β-tricalcium phosphate (β-TCP) and biphasic hydroxyapatite/β-tricalcium phosphate composites (HTCP) were analyzed by measuring thermally stimulated depolarization currents (TSDC). The samples were thermoelectrically polarized at 500 °C under a DC electric field with a magnitude of 5 kV/cm. The biphasic samples were also polarized under electric fields with different magnitudes: 2, 3, 4 and 5 kV/cm. Additionally, the depolarization processes detected in the TSDC measurements were correlated with dielectric relaxation processes observed in impedance spectroscopy (IS) measurements. The results indicate that the β-TCP crystalline phase has a considerable higher ability to store electrical charge compared with the Hap phase. This indicates that it has a suitable composition and structure for ionic conduction and establishment of a large electric charge density, providing great potential for orthopaedic applications.

  19. Synthesis of chitosan/hydroxyapatite membranes coated with hydroxycarbonate apatite for guided tissue regeneration purposes

    Science.gov (United States)

    Fraga, Alexandre Félix; Filho, Edson de Almeida; Rigo, Eliana Cristina da Silva; Boschi, Anselmo Ortega

    2011-02-01

    Chitosan, which is a non-toxic, biodegradable and biocompatible biopolymer, has been widely researched for several applications in the field of biomaterials. Calcium phosphate ceramics stand out among the so-called bioceramics for their absence of local or systemic toxicity, their non-response to foreign bodies or inflammations, and their apparent ability to bond to the host tissue. Hydroxyapatite (HA) is one of the most important bioceramics because it is the main component of the mineral phase of bone. The aim of this work was to produce chitosan membranes coated with hydroxyapatite using the modified biomimetic method. Membranes were synthesized from a solution containing 2% of chitosan in acetic acid (weight/volume) via the solvent evaporation method. Specimens were immersed in a sodium silicate solution and then in a 1.5 SBF (simulated body fluid) solution. The crystallinity of the HA formed over the membranes was correlated to the use of the nucleation agent (the sodium silicate solution itself). Coated membranes were characterized by means of scanning electron microscopy - SEM, X-ray diffraction - XRD, and Fourier transform infrared spectroscopy - FTIR. The results indicate a homogeneous coating covering the entire surface of the membrane and the production of a semi-crystalline hydroxyapatite layer similar to the mineral phase of human bone.

  20. Synthesis of chitosan/hydroxyapatite membranes coated with hydroxycarbonate apatite for guided tissue regeneration purposes

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, Alexandre Felix [Federal University of Sao Carlos, Department of Materials Engineering, DEMa, UFSCar, Sao Carlos, SP (Brazil); Almeida Filho, Edson de, E-mail: edsonafilho@yahoo.com.br [University Estadual Paulista, Department of Physical Chemistry - IQ, Araraquara, SP (Brazil); Silva Rigo, Eliana Cristina da [University of Sao Paulo, Department of Basic Science - FZEA-ZAB, Pirassununga, SP (Brazil); Ortega Boschi, Anselmo [Federal University of Sao Carlos, Department of Materials Engineering, DEMa, UFSCar, Sao Carlos, SP (Brazil)

    2011-02-15

    Chitosan, which is a non-toxic, biodegradable and biocompatible biopolymer, has been widely researched for several applications in the field of biomaterials. Calcium phosphate ceramics stand out among the so-called bioceramics for their absence of local or systemic toxicity, their non-response to foreign bodies or inflammations, and their apparent ability to bond to the host tissue. Hydroxyapatite (HA) is one of the most important bioceramics because it is the main component of the mineral phase of bone. The aim of this work was to produce chitosan membranes coated with hydroxyapatite using the modified biomimetic method. Membranes were synthesized from a solution containing 2% of chitosan in acetic acid (weight/volume) via the solvent evaporation method. Specimens were immersed in a sodium silicate solution and then in a 1.5 SBF (simulated body fluid) solution. The crystallinity of the HA formed over the membranes was correlated to the use of the nucleation agent (the sodium silicate solution itself). Coated membranes were characterized by means of scanning electron microscopy - SEM, X-ray diffraction - XRD, and Fourier transform infrared spectroscopy - FTIR. The results indicate a homogeneous coating covering the entire surface of the membrane and the production of a semi-crystalline hydroxyapatite layer similar to the mineral phase of human bone.

  1. Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications.

    Science.gov (United States)

    Nazeer, Muhammad Anwaar; Yilgör, Emel; Yilgör, Iskender

    2017-11-01

    Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Self-Setting Calcium Orthophosphate Formulations

    Science.gov (United States)

    Dorozhkin, Sergey V.

    2013-01-01

    In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

  3. Hybrid Calcium Phosphate Coatings for Titanium Implants

    Science.gov (United States)

    Kharapudchenko, E.; Ignatov, V.; Ivanov, V.; Tverdokhlebov, S.

    2017-01-01

    Hybrid multilayer coatings were obtained on titanium substrates by the combination of two methods: the micro-arc oxidation in phosphoric acid solution with the addition of calcium compounds to high supersaturated state and RF magnetron sputtering of the target made of synthetic hydroxyapatite. 16 different groups of coatings were formed on titanium substrates and in vitro studies were conducted in accordance with ISO 23317 in the solution simulating body fluid. The studies using SEM, XRD of the coatings of the samples before and after exposure to SBF were performed. The features of morphology, chemical and phase composition of the studied coatings are shown.

  4. X-Ray Diffraction Studies on the Thermal Stability of Calcium ...

    African Journals Online (AJOL)

    acer

    X-Ray Diffraction Studies on the Thermal Stability of Calcium-Strontium Hydroxyapatite ... X- ray diffraction technique has been used by several researchers to investigate the individual effect of some elements on the formation and some properties of apatite in synthetic and .... is consistent with the larger ionic radius of.

  5. Novel tea polyphenol-modified calcium phosphate nanoparticle and its remineralization potential

    NARCIS (Netherlands)

    He, L.; Deng, D.; Zhou, X.; Cheng, L.; ten Cate, J.M.; Li, J.; Li, X.; Crielaard, W.

    2015-01-01

    Tea polyphenols (TP) are not only potent antimicrobial and antioxidant agents but also effective modifiers in the formation of nanosized crystals. Since nano-hydroxyapatite (n-HA) is known to enhance remineralization of dental hard tissue, our aims were to synthesize nanosized calcium phosphate

  6. X-Ray Diffraction Studies on the Thermal Stability of Calcium ...

    African Journals Online (AJOL)

    Calcium-Strontium hydroxyapatite (HAP) solid solutions in the presence and absence of diethylamine (DEA) were prepared by the method of co-precipitation from basic media. The samples were heated at 773.15K in a furnace. Characterization of the samples by x-ray powder diffractometry, atomic absorption spectroscopy ...

  7. Microbial phytase-induced calcium-phosphate precipitation : A potential soil stabilization method

    NARCIS (Netherlands)

    Roeselers, G.; Van Loosdrecht, M.C.M.

    2011-01-01

    Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca2+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture of the

  8. Structural evaluation and animal implantation of porous eggshell wastederived hydroxyapatite graft as bone substitution

    Directory of Open Access Journals (Sweden)

    Yudha Mathan Sakti Rahadyan Magetsari

    2014-08-01

    Full Text Available The development of hydroxyapatite graft with high economically value is needed for orthopedic practice in developing countries. Eggsell waste is well known as natural substance for calcium resource. It has been used as raw material in producing hydroxyapatite. This study was conducted to synthesize porous hydroxyapatite from eggshell waste and evaluate its activity as bone substitution. The porous hydroxyapatite graft was manufactured from eggshell and sugar as a raw material using hydrothermal process. The porous eggshell waste-derived hydroxyapatite (EW-HAP graft was characterized using X ray difractometer (XRD and analytical scanning electron microscope (SEM and compared with commercial hydroxyapatite (HAP JCPDS 09-432 graft (Bangros® as standard. The porous EW-HAP graft obtained was then implanted on critically sized femoral defects surgically created in the right thigh of male Wistar rats (Rattus norvegicus with Bangros® as control. Radiological examination using XRD and histological examination using hematoxyline-and-eosin staining of the bone femour were performed at 28 days after implantation. The results showed that the XRD pattern for EW-HAP was likely similar with the HAP standard. However, the SEM examination showed that the pasticle size of EW-HAP graft (2.5-3 μm was higher than those HAP standard graft (1.5-2 μm. Radiographs according to the International of Limb Salvage (ISOLS radiological evaluation system between EW-HAP graft (6.1 ± 1.45 and HAP control graft (6.9 ± 2.10 was not significantly different (p>0.05. Moreover, histological examination according to Lane and Shandu scoring system between the both graft (4.0 ± 0.94 versus 4.4 ± 0.92 was also not significantly different (p>0.05. It can be concluded that the structure EW-HAP graft is similar with HAP graft standard. The both grafts have also equal outcome as bone substitution.

  9. Composition of chitosan-hydroxyapatite-collagen composite scaffold evaluation after simulated body fluid immersion as reconstruction material

    Science.gov (United States)

    Verisqa, F.; Triaminingsih, S.; Corputty, J. E. M.

    2017-08-01

    Hydroxyapatite (HA) formation is one of the most important aspects of bone regeneration. Because domestically made chitosan-hydroxyapatite-collagen composite scaffolding from crab shell and bovine bone and tendon has potential as a maxillofacial reconstruction material, the material’s HA-forming ability requires evaluation. The aim of this research is to investigate chitosan-hydroxyapatite-collagen composite scaffold’s potential as a maxillofacial reconstruction material by observing the scaffold’s compositional changes. Scaffold specimens were immersed in 37°C simulated body fluid (SBF) for periods of 2, 4, 6, and 8 days. Scaffold composition was then evaluated by using energy dispersive spectroscopy (EDS). The calcium (Ca) and phosphorus (P) percentages of the scaffold were found to increase following SBF immersion. The high Ca/P ratio (3.82) on the scaffold indicated HA formation. Ion exchange played a significant role in the increased percentages of Ca and P, which led to new HA layer formation. The scaffold’s HA acted as a nucleation site of Ca and P from the SBF, with collagen and chitosan as the scaffold’s matrix. Chitosan-hydroxyapatite-collagen composite scaffold shows potential as a maxillofacial reconstruction material, since its composition favors HA formation.

  10. Precipitation of hydroxyapatite on electrospun polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds for bone tissue engineering.

    Science.gov (United States)

    Shanmugavel, Suganya; Reddy, Venugopal Jayarama; Ramakrishna, Seeram; Lakshmi, B S; Dev, Vr Giri

    2014-07-01

    Advances in electrospun nanofibres with bioactive materials have enhanced the scope of fabricating biomimetic scaffolds for tissue engineering. The present research focuses on fabrication of polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds by electrospinning followed by hydroxyapatite deposition by calcium-phosphate dipping method for bone tissue engineering. Morphology, composition, hydrophilicity and mechanical properties of polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds along with controls polycaprolactone and polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds were examined by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle and tensile tests, respectively. Adipose-derived stem cells cultured on polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds displayed highest cell proliferation, increased osteogenic markers expression (alkaline phosphatase and osteocalcin), osteogenic differentiation and increased mineralization in comparison with polycaprolactone control. The obtained results indicate that polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds have appropriate physico-chemical and biological properties to be used as biomimetic scaffolds for bone tissue regeneration. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  11. Haemodynamic optimisation in lower limb arterial surgery

    DEFF Research Database (Denmark)

    Bisgaard, J; Gilsaa, T; Rønholm, E

    2012-01-01

    index was optimised by administering 250 ml aliquots of colloid intraoperatively and during the first 6 h post-operatively. Following surgery, fluid optimisation was supplemented with dobutamine, if necessary, targeting an oxygen delivery index level ≥ 600 ml/min(/) m(2) in the intervention group...

  12. The robust optimisation of metal forming processes

    NARCIS (Netherlands)

    Bonte, M.H.A.; van den Boogaard, Antonius H.; van Ravenswaaij, R.

    2007-01-01

    Robustness, reliability, optimisation and Finite Element simulations are of major importance to improve product quality and reduce costs in the metal forming industry. In this paper, we review several possibilities for combining these techniques and propose a robust optimisation strategy for metal

  13. Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Nava, Vincenzo; Topper, Mathew B. R.

    2017-01-01

    This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC) arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation...

  14. Optimising towards robust metal forming processes

    NARCIS (Netherlands)

    Bonte, M.H.A.; van den Boogaard, Antonius H.; Carleer, B.D.

    2006-01-01

    Product improvement and cost saving have always been important goals in the metal forming industry. Numerical optimisation can help to achieve these goals, but optimisation with a deterministic approach will often lead to critical process settings, such that the slightest variation in e.g. material

  15. Amorphous calcium phosphate and its application in dentistry

    Directory of Open Access Journals (Sweden)

    Sun Wei-bin

    2011-07-01

    Full Text Available Abstract Amorphous Calcium Phosphate (ACP is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry.

  16. Thickness of hydroxyapatite nanocrystal controls mechanical properties of the collagen-hydroxyapatite interface.

    Science.gov (United States)

    Qin, Zhao; Gautieri, Alfonso; Nair, Arun K; Inbar, Hadass; Buehler, Markus J

    2012-01-31

    Collagen-hydroxyapatite interfaces compose an important building block of bone structures. While it is known that the nanoscale structure of this elementary building block can affect the mechanical properties of bone, a systematic understanding of the effect of the geometry on the mechanical properties of this interface between protein and mineral is lacking. Here we study the effect of geometry, different crystal surfaces, and hydration on the mechanical properties of collagen-hydroxyapatite interfaces from an atomistic perspective, and discuss underlying deformation mechanisms. We find that the presence of hydroxyapatite significantly enhances the tensile modulus and strength compared with a tropocollagen molecule alone. The stiffening effect is strongly dependent on the thickness of the mineral crystal until a plateau is reached at 2 nm crystal thickness. We observe no significant differences due to the mineral surface (Ca surface vs OH surface) or due to the presence of water. Our result shows that the hydroxyapatite crystal with its thickness confined to the nanometer size efficiently increases the tensile modulus and strength of the collagen-hydroxyapatite composite, agreeing well with experimental observations that consistently show the existence of extremely thin mineral flakes in various types of bones. We also show that the collagen-hydroxyapatite interface can be modeled with an elastic network model which, based on the results of atomistic simulations, provides a good estimate of the surface energy and other mechanical features. © 2011 American Chemical Society

  17. Design Optimisation of Coronary Artery Stent Systems.

    Science.gov (United States)

    Bressloff, Neil W; Ragkousis, Giorgos; Curzen, Nick

    2016-02-01

    In recent years, advances in computing power and computational methods have made it possible to perform detailed simulations of the coronary artery stenting procedure and of related virtual tests of performance (including fatigue resistance, corrosion and haemodynamic disturbance). Simultaneously, there has been a growth in systematic computational optimisation studies, largely exploiting the suitability of surrogate modelling methods to time-consuming simulations. To date, systematic optimisation has focussed on stent shape optimisation and has re-affirmed the complexity of the multi-disciplinary, multi-objective problem at hand. Also, surrogate modelling has predominantly involved the method of Kriging. Interestingly, though, optimisation tools, particularly those associated with Kriging, haven't been used as efficiently as they could have been. This has especially been the case with the way that Kriging predictor functions have been updated during the search for optimal designs. Nonetheless, the potential for future, carefully posed, optimisation strategies has been suitably demonstrated, as described in this review.

  18. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  19. Continuous microwave flow synthesis of mesoporous hydroxyapatite.

    Science.gov (United States)

    Akram, Muhammad; Alshemary, Ammar Z; Goh, Yi-Fan; Wan Ibrahim, Wan Aini; Lintang, Hendrik O; Hussain, Rafaqat

    2015-11-01

    We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca(2+) ion released in SBF solution. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Hydroxyapatite, a biomaterial: Its chemical synthesis ...

    Indian Academy of Sciences (India)

    Hydroxyapatite, a biomaterial: Its chemical synthesis, characterization and study of biocompatibility prepared from shell of garden snail,. Helix aspersa. ANJUVAN SINGH. Department of Biotechnology and Biosciences, Lovely Professional University, Phagwara 144 411, India. MS received 10 February 2010; revised 20 July ...

  1. Preparation of microstructured hydroxyapatite microspheres using ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Hydroxyapatite (HAP) microspheres with peculiar spheres-in-sphere morphology were prepared by using oil-in-water emulsions and solvent evaporation technique. Ethylene vinyl acetate co-polymer (EVA) was used as the binder material. Preparation of HAP/EVA microspheres was followed by the thermal de-.

  2. Fabrication and characterization of porous hydroxyapatite ocular ...

    Indian Academy of Sciences (India)

    Unknown

    areas of medicine (Aoki et al 1987; Grote 1987; Shin et al 1992) also. The use of hydroxyapatite as an ocular .... the experimental error, throughout the whole process of fabrication. The median particle size of HAp powder used ... per medication and resolution took place within the 12th post-operative day (figures 9 a–d).

  3. Preparation of microstructured hydroxyapatite microspheres using ...

    Indian Academy of Sciences (India)

    Each microsphere of 100–1000 m was in turn composed of spherical hydroxyapatite granules of 2–15 m size which were obtained by spray drying the precipitated HAP. The parameters such as percentage of initial HAP loading, type of stabilizer, concentration of stabilizer, stirring speed and temperature of microsphere ...

  4. Suitability evaluation of sol-gel derived Si-substituted hydroxyapatite for dental and maxillofacial applications through in vitro osteoblasts response.

    Science.gov (United States)

    Balamurugan, A; Rebelo, A H S; Lemos, A F; Rocha, J H G; Ventura, J M G; Ferreira, J M F

    2008-10-01

    Si-hydroxyapatite (Si-HAP) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. The aim of this investigation was to study the effect of Si substitution into the hydroxyapatite matrices and evaluate the biocompatibility effects of Si-HAP material in vitro with human osteoblasts. Silicon-substituted hydroxyapatite (Si-HAP) bioceramic materials were prepared by incorporating small amounts of silicon into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HAP] through a sol-gel method. A series of silicon substitutions ranging from 0, 1, 3 and 5 mol%, which are comparable to the measured silicon contents in natural bone, were performed. Single-phase Si-HAP was obtained upon calcining the as-prepared powders up to 800 degrees C since no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP) or calcium oxide (CaO), were identified by X-ray diffraction analysis. The effects of silicon-substituted hydroxyapatite (Si-HAP) materials towards the responses of human osteoblast-like (HOB) cells were investigated and compared with pure hydroxyapatite. The Si-HAP indicated a significant increase in cell growth density with culture time irrespective of the amount of Si substituted in HAP. A high Si content (5 mol%) appears to promote rapid bone mineralization, since large amount of calcium phosphate minerals started to develop across the ECM by day 31 for a sample containing 5 mol% Si. On the other hand, a high Si content may result in fast dissolution of the material, owing to a decrease of HAP crystallite size, which might not be ideal for cell attachment for prolonged time periods. An optimum level of Si appears to exist at 3 mol%, which balances these effects.

  5. Block-copolymer-assisted synthesis of hydroxyapatite nanoparticles with high surface area and uniform size

    Directory of Open Access Journals (Sweden)

    Yu-Tzu Huang, Masataka Imura, Yoshihiro Nemoto, Chao-Hung Cheng and Yusuke Yamauchi

    2011-01-01

    Full Text Available We report the synthesis of hydroxyapatite nanoparticles (HANPs by the coprecipitation method using calcium D-gluconate and potassium hydrogen phosphate as the sources of calcium and phosphate ions, respectively, and the triblock copolymer F127 as a stabilizer. The HANPs were characterized using scanning electron microscopy, x-ray diffraction, and nitrogen adsorption/desorption isotherms. Removal of F127 by solvent extraction or calcination alters the structure of HANPs. The solvent-extracted HANPs were single crystals with their lang001rang axis oriented along the rod axis of the HANP, whereas the calcined HANPs contained two crystal phases that resulted in a spherical morphology. The calcined HANPs had much higher surface area (127 m2 g−1 than the solvent-extracted HANPs (44 m2 g−1.

  6. Optimising Comprehensibility in Interlingual Translation

    DEFF Research Database (Denmark)

    Nisbeth Jensen, Matilde

    2015-01-01

    . It is argued that Plain Language writing is a type of intralingual translation as it involves rewriting or translating a complex monolingual text into comprehensible language. Based on Plain Language literature, a comprehensibility framework is elaborated, which is subsequently exemplified through...... the functional text type of Patient Information Leaflet. Finally, the usefulness of applying the principles of Plain Language and intralingual translation for optimising comprehensibility in interlingual translation is discussed....... information on medication and tax information. Such texts are often written by experts and received by lay people, and, in today’s globalised world, they are often translated as well. In these functional texts, the receiver is not a mere recipient of information, but s/he needs to be able to act upon it...

  7. Fluid Mechanics Optimising Organic Synthesis

    Science.gov (United States)

    Leivadarou, Evgenia; Dalziel, Stuart

    2015-11-01

    The Vortex Fluidic Device (VFD) is a new ``green'' approach in the synthesis of organic chemicals with many industrial applications in biodiesel generation, cosmetics, protein folding and pharmaceutical production. The VFD is a rapidly rotating tube that can operate with a jet feeding drops of liquid reactants to the base of the tube. The aim of this project is to explain the fluid mechanics of the VFD that influence the rate of reactions. The reaction rate is intimately related to the intense shearing that promotes collision between reactant molecules. In the VFD, the highest shears are found at the bottom of the tube in the Rayleigh and the Ekman layer and at the walls in the Stewardson layers. As a step towards optimising the performance of the VFD we present experiments conducted in order to establish the minimum drop volume and maximum rotation rate for maximum axisymmetric spreading without fingering instability. PhD candidate, Department of Applied Mathematics and Theoretical Physics.

  8. Optimising costs in WLCG operations

    CERN Document Server

    Pradillo, Mar; Flix, Josep; Forti, Alessandra; Sciabà, Andrea

    2015-01-01

    The Worldwide LHC Computing Grid project (WLCG) provides the computing and storage resources required by the LHC collaborations to store, process and analyse the 50 Petabytes of data annually generated by the LHC. The WLCG operations are coordinated by a distributed team of managers and experts and performed by people at all participating sites and from all the experiments. Several improvements in the WLCG infrastructure have been implemented during the first long LHC shutdown to prepare for the increasing needs of the experiments during Run2 and beyond. However, constraints in funding will affect not only the computing resources but also the available effort for operations. This paper presents the results of a detailed investigation on the allocation of the effort in the different areas of WLCG operations, identifies the most important sources of inefficiency and proposes viable strategies for optimising the operational cost, taking into account the current trends in the evolution of the computing infrastruc...

  9. [Hydroxyapatite for experimental laryngotracheal reconstruction].

    Science.gov (United States)

    Qin, Y; Yu, M; Han, D

    2001-08-01

    The porous hydroxyapatite (HA) tubiform prosthesis was employed for reconstruction of large circumferential defect of the larynx and cervical trachea. The biocompatibility, bioactivity and biofunctionality of the HA prosthesis were evaluated, and the feasibility for laryngotracheal reconstruction was discussed. Twelve healthy canines were used to establish the experimental models, a large portion of cricoid cartilage and upper ten-ring segment of cervical trachea were resected and substituted with a corresponding 5 cm HA prosthesis by end-to-end anastomosis. Six months later, the eight survival canines were sacrificed and the HA prostheses with surrounding tissues were removed. They were observed in decalcified sections by optical microscopy and scanning electron microscopy. Two canines died in the immediate postoperative period with unknown reason and another two deaths were attributed to obstruction caused by the complete dislocation of the HA prostheses owing to rupture of the sutures within three weeks after operation. Eight canines survived up to six months. The implanted HA prostheses were tolerated in all cases without any rejection and dislocation or shift. An excellent airway was obtained and no signs of dyspnea and suffocation were found though there were hypergranulation and scar formation occurred at the site of anastomosis. Morphologic examination revealed that collagen fibers, new vessels and plenty of cells penetrated deeply into the pores of HA, and occupying the outer two third of HA wall. HA prostheses were surrounded by connective tissues and anchored firmly to the neighboring tissues, including the ends of the cricoid and tracheal cartilage by ingrowths of cartilaginous tissue into the macropores of the HA. However, the luminal surface of HA prosthesis was not covered at all section levels by respiratory mucosa. The implantation of the porous HA tubiform prosthesis can maintain the normal respiratory function of the experimental canines, but the

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

    Energy Technology Data Exchange (ETDEWEB)

    Parente, P., E-mail: pparente@icv.csic.es [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, Madrid 28049 (Spain); Savoini, B. [Departamento de Fisica, Universidad Carlos III de Madrid, Avda. Universidad 30, Leganes 28911 (Spain); Ferrari, B. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, Madrid 28049 (Spain); Monge, M.A.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, Avda. Universidad 30, Leganes 28911 (Spain); Sanchez-Herencia, A.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, Madrid 28049 (Spain)

    2013-03-01

    The capability of the colloidal method to produce yttria (Y{sub 2}O{sub 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{sub 2}O{sub 3} has been applied, and the effect of 10 wt.% Y{sub 2}O{sub 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{sub 2}O{sub 3} addition on decomposition mechanisms of synthetic HA. Results show that incorporation of Y{sub 2}O{sub 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{sup 2+} with Y{sup 3+} ions appears to promote the formation of OH{sup -} vacancies, which could improve the conductive properties of HA favorable to osseointegration. - Highlights: Black-Right-Pointing-Pointer We reveal the influence of Y{sub 2}O{sub 3} on thermal stability of hydroxyapatite. Black-Right-Pointing-Pointer Incorporation of Y{sub 2}O{sub 3} delays decomposition of hydroxyapatite to calcium phosphates. Black-Right-Pointing-Pointer Addition of Y{sub 2}O{sub 3} enables sintering conditions more favorable to the densification.

  11. Magnetic properties study on Fe-doped calcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Silva, C C; Valente, M A [Physics Department (I3N), Aveiro University (Portugal); Vasconcelos, I F [Metallurgical and Materials Engineering Department, Federal University of Ceara, Campus do Pici, 714 Block, 60455-760, Fortaleza, Ceara (Brazil); Sombra, A S B [Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Department of Physics, Federal University of Ceara, Campus do Pici, Postal Code 6030, 60455-760, Fortaleza, Ceara (Brazil)], E-mail: ccsilva@ua.pt, E-mail: ccsilva@fisica.ufc.br

    2009-11-15

    Calcium phosphates are very important for applications in medicine due to their properties such as biocompatibility and bioactivity. In order to enhance these properties, substitution of calcium with other ions has been proposed. Partial substitution of calcium by different ions has been made in order to improve the properties of the calcium phosphates and also to allow new applications of apatite in medicine. In this work, hydroxyapatite [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}-HAP] was prepared by high-energy dry milling (20 h) and mixed with iron oxide (5 wt.%). The mixture was calcinated at 900 deg. C for 5 h with a heating rate of 3 deg. C min{sup -1} in an attempt to introduce iron oxide into the HAP structure. The sintered sample was characterized using x-ray diffraction (XRD) and magnetization. The {sup 57}Fe-Moessbauer spectra of the calcium phosphate oxides were also measured, revealing the presence of iron in three different phases: Ca{sub 2}Fe{sub 2}O{sub 5}, Fe{sub 2}O{sub 3} and hydroxyapatite.

  12. Synthesis and characterization of a nanostructured matrix hydroxyapatite ceramic bone reconstruction; Sintese e caracterizacao de uma matriz ceramica nanoestruturada de hidroxiapatita para reconstituicao ossea

    Energy Technology Data Exchange (ETDEWEB)

    Correa, P.; Camargo, N.H.A.; Silva, D.F. [Universidade do Estado de Santa Catarina (PGCEM/UDESC), SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2012-07-01

    The nanostructured ceramics have been shown promise as biomaterials for bone reconstruction. Among calcium phosphates, hydroxyapatite Ca/P ratio = 1.67 mol stands out because of its crystallographic similarity with the mineral bone phase and biocompatibility. This work was based on synthesis and characterization of a nanostructured hydroxyapatite for use in reconstituting bone tissue. The synthesis method for obtaining the bioceramic powder occurred at process of dissolution/precipitation, involving CaO solid/liquid and phosphoric acid required for forming the composition of Ca/P = 1.67 mole. The material recovered from the synthesis was calcined at 900 ° C/2h, providing the hydroxyapatite powder nanometer. This was subjected to mechanical fragmentation process in mill attritor, providing a hydroxyapatite with modified surface morphology. The results presented relate to morphological characterization studies (SEM), mineralogical (XRD), chemical (FTIR) and particle size distribution, using the laser particle size analysis method. Such results showed the formation of hydroxyapatite phase and morphology satisfactory for use in reconstituting bone tissue.

  13. Nanomechanical properties of hydroxyapatite (HAP) with DAB dendrimers (poly-propylene imine) coatings onto titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Charitidis, Costas A., E-mail: charitidis@chemeng.ntua.gr [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou, Zografou, 15780 Athens (Greece); Skarmoutsou, Amalia [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou, Zografou, 15780 Athens (Greece); Tsetsekou, Athena; Brasinika, Despina [School of Mining Engineering and Metallurgy, National Technical University of Athens, Iroon Polytechniou, Zografou, 15780 Athens (Greece); Tsiourvas, Dimitris [National Centre for Scientific Research “Demokritos”, Institute of Physical Chemistry, Agia Paraskevi, 15310 Athens (Greece)

    2013-04-20

    Highlights: ► The synthesis of hydroxyapatite (HAP) nanoparticles in the presence of a cationic fourth generation diaminobutane poly(propylene imine) dendrimer (DAB). ► The nanomechanical properties of different HAP-DAB coatings onto titanium surfaces. ► Wear resistance and adhesion properties of the synthesized coatings quantified by nanoindentation data analysis. -- Abstract: Coatings of hydroxyapatite (HAP) nanorods onto titanium surfaces were synthesized with the aim to improve coatings’ mechanical properties and adhesion to the substrate. The coatings are consisting of HAP nanorods synthesized in the presence of a cationic fourth generation diaminobutane poly(propylene imine) dendrimer (DAB) bearing 32 amine end groups employing varying calcium: dendrimer ratios and varying hydrothermal treatments. The quality, surface morphology and structure of the coatings were characterized with X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and energy dispersive microanalysis. Wear resistance and adhesion properties of the coatings onto titanium substrates were studied through nanoindentation analysis. The experimental conditions, namely the calcium: dendrimer molar ratio and the hydrothermal treatment temperature were carefully selected; thus, it was possible to produce coatings of high hardness and elastic modulus values (ranging between 1–4.5 GPa and 40–150 GPa, respectively) and/or high wear resistance and plastic deformation values.

  14. Dynamic light scattering study of inhibition of nucleation and growth of hydroxyapatite crystals by osteopontin.

    Directory of Open Access Journals (Sweden)

    John R de Bruyn

    Full Text Available We study the effect of isoforms of osteopontin (OPN on the nucleation and growth of crystals from a supersaturated solution of calcium and phosphate ions. Dynamic light scattering is used to monitor the size of the precipitating particles and to provide information about their concentration. At the ion concentrations studied, immediate precipitation was observed in control experiments with no osteopontin in the solution, and the size of the precipitating particles increased steadily with time. The precipitate was identified as hydroxyapatite by X-ray diffraction. Addition of native osteopontin (nOPN extracted from rat bone caused a delay in the onset of precipitation and reduced the number of particles that formed, but the few particles that did form grew to a larger size than in the absence of the protein. Recombinant osteopontin (rOPN, which lacks phosphorylation, caused no delay in initial calcium phosphate precipitation but severely slowed crystal growth, suggesting that rOPN inhibits growth but not nucleation. rOPN treated with protein kinase CK2 to phosphorylate the molecule (p-rOPN produced an effect similar to that of nOPN, but at higher protein concentrations and to a lesser extent. These results suggest that phosphorylations are critical to OPN's ability to inhibit nucleation, whereas the growth of the hydroxyapatite crystals is effectively controlled by the highly acidic OPN polypeptide. This work also demonstrates that dynamic light scattering can be a powerful tool for delineating the mechanism of protein modulation of mineral formation.

  15. Microwave-assisted synthesis of hydroxyapatite for the removal of lead(II) from aqueous solutions.

    Science.gov (United States)

    Hasret, Erdem; Ipekoglu, Mehmet; Altintas, Sabri; Ipekoglu, Nursen A

    2011-08-01

    This study has the objective to evaluate the lead(II) removal capacity of hydroxyapatite powder synthesized by microwave as an alternative method to decrease production time and cost. Hydroxyapatite (HA) was synthesized by a microwave-assisted precipitation method using calcium nitrate and ammonium hydrogen phosphate as calcium and phosphorus sources, respectively. X-ray diffraction and Fourier transform infrared results clearly revealed that the resulting powder was HA with high purity and crystallinity. The obtained powder was used for the removal of lead(II) from aqueous solutions. The effects of pH, amount of adsorbent, initial lead(II) concentration, and contact time were studied in batch experiments. In the adsorption experiments, maximum lead(II) retention was obtained at pH 6. Adsorption equilibrium was established after 40 min. It was found that the adsorption of lead(II) on HA was correlated well (R (2) = 0.958) with the Freundlich equation for the concentration range studied. Both ion exchange and adsorption process were thought to exist in the removal process. This study indicates that easily and rapidly synthesized HA by microwave-assisted precipitation method could be used as an efficient adsorbent for removal of lead(II) from aqueous solutions.

  16. Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C.; Szecsody, James (PNNL); Rigali, Mark J.; Vermuel, Vince (PNNL); Leullen, Jon (AECOM)

    2016-02-01

    We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.

  17. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Bacterial Cellulose-Hydroxyapatite Nanocomposites for Bone Regeneration

    Directory of Open Access Journals (Sweden)

    S. Saska

    2011-01-01

    Full Text Available 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.

  20. Biomimetic growth of hydroxyapatite on phosphorylated electrospun cellulose nanofibers.

    Science.gov (United States)

    Li, Kaina; Wang, Jiangnan; Liu, Xinqing; Xiong, Xiaopeng; Liu, Haiqing

    2012-11-06

    In biomimicking the formation of collagen fiber/hydroxyapatite (HAp) in natural bone, electrospun cellulose nanofiber (CelluNF)/HAp composites were synthesized in simulated body fluid (SBF). Their morphology and structure were characterized by SEM, TEM, XRD and XPS. CelluNFs showed low bioactivity in inducing the growth of HAp. In order to improve this ability, CelluNFs were slightly phosphorylated with a degree of substitution of phosphate group of 0.28. The modified CelluNFs were highly effective in guiding the HAp growth along the fibers. The HAp crystal size in the composites was ca. 24 nm, and the lattice spacing of (211) plane was 2.83 Å. It was found that the HAps in the composites were calcium deficient. The CelluNF/HAp composites are highly porous materials with micro-, meso-, and macro-pores. A mechanism for the HAp growth on CelluNFs was presented. Such CelluNF/HAp composites can be potentially useful in the field of bone tissue engineering. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Obtaining hydroxyapatite coatings on titanium by the biomimetic method; Obtencion de recubrimientos de hidroxiapatita sobre titanio mediante el metodo biomimetico

    Energy Technology Data Exchange (ETDEWEB)

    Paz, A.; Martin, Y.; Pazos, L. M.; Parodi, M. B.; Ybarra, G. O.; Gonzalez, J. E.

    2011-07-01

    In this work, a study about the deposition of hydroxyapatite on a titanium substrate employing the biomimetic method is presented. A solution with high content of calcium and phosphorus (SCS) was used. In addition, activation of titanium with hydrogen peroxide and hydrochloric acid and a subsequent heat treatment was performed. The characterization of materials used and the coating obtained was carried out by Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). As a result of the activation processes a hydrated titanium oxide was formed. On the active surface, a coating of hydroxyapatite was obtained after a period of 24 h, which has a thickness of about 2-4 {mu}m. (Author) 21 refs.

  2. Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

    Science.gov (United States)

    Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

    2013-01-01

    A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy. PMID:22983020

  3. Mechanical properties and biocompatibility of the sputtered Ti doped hydroxyapatite.

    Science.gov (United States)

    Vladescu, A; Padmanabhan, S C; Ak Azem, F; Braic, M; Titorencu, I; Birlik, I; Morris, M A; Braic, V

    2016-10-01

    The hydroxyapatite enriched with Ti were prepared as possible candidates for biomedical applications especially for implantable devices that are in direct contact to the bone. The hydroxyapatites with different Ti content were prepared by RF magnetron sputtering on Ti-6Al-4V alloy using pure hydroxyapatite and TiO2 targets. The content of Ti was modified by changing the RF power fed on TiO2 target. The XPS and FTIR analyses revealed the presence of hydroxyapatite structure. The hardness and elastic modulus of the hydroxyapatite were increased by Ti addition. After 5 days of culture, the cell viability of the Ti-6Al-4V was enhanced by depositing with undoped or doped hydroxyapatite. The Ti additions led to an increase in cell viability of hydroxyapatite, after 5 days of culture. The electron microscopy showed the presence of more cells on the surface of Ti-enriched hydroxyapatite than those observed on the surface of the uncoated alloys or undoped hydroxyapatite. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Optimising uncertainty in physical sample preparation.

    Science.gov (United States)

    Lyn, Jennifer A; Ramsey, Michael H; Damant, Andrew P; Wood, Roger

    2005-11-01

    Uncertainty associated with the result of a measurement can be dominated by the physical sample preparation stage of the measurement process. In view of this, the Optimised Uncertainty (OU) methodology has been further developed to allow the optimisation of the uncertainty from this source, in addition to that from the primary sampling and the subsequent chemical analysis. This new methodology for the optimisation of physical sample preparation uncertainty (u(prep), estimated as s(prep)) is applied for the first time, to a case study of myclobutanil in retail strawberries. An increase in expenditure (+7865%) on the preparatory process was advised in order to reduce the s(prep) by the 69% recommended. This reduction is desirable given the predicted overall saving, under optimised conditions, of 33,000 pounds Sterling per batch. This new methodology has been shown to provide guidance on the appropriate distribution of resources between the three principle stages of a measurement process, including physical sample preparation.

  5. Nature-Inspired Chemical Reaction Optimisation Algorithms.

    Science.gov (United States)

    Siddique, Nazmul; Adeli, Hojjat

    2017-01-01

    Nature-inspired meta-heuristic algorithms have dominated the scientific literature in the areas of machine learning and cognitive computing paradigm in the last three decades. Chemical reaction optimisation (CRO) is a population-based meta-heuristic algorithm based on the principles of chemical reaction. A chemical reaction is seen as a process of transforming the reactants (or molecules) through a sequence of reactions into products. This process of transformation is implemented in the CRO algorithm to solve optimisation problems. This article starts with an overview of the chemical reactions and how it is applied to the optimisation problem. A review of CRO and its variants is presented in the paper. Guidelines from the literature on the effective choice of CRO parameters for solution of optimisation problems are summarised.

  6. Layout Optimisation of Wave Energy Converter Arrays

    Directory of Open Access Journals (Sweden)

    Pau Mercadé Ruiz

    2017-08-01

    Full Text Available This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA, a genetic algorithm (GA and the glowworm swarm optimisation (GSO algorithm. The results show slightly higher performances for the latter two algorithms; however, the first turns out to be significantly less computationally demanding.

  7. User perspectives in public transport timetable optimisation

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2014-01-01

    The present paper deals with timetable optimisation from the perspective of minimising the waiting time experienced by passengers when transferring either to or from a bus. Due to its inherent complexity, this bi-level minimisation problem is extremely difficult to solve mathematically, since...... timetable optimisation is a non-linear non-convex mixed integer problem, with passenger flows defined by the route choice model, whereas the route choice model is a non-linear non-continuous mapping of the timetable. Therefore, a heuristic solution approach is developed in this paper, based on the idea...... of varying and optimising the offset of the bus lines. Varying the offset for a bus line impacts the waiting time passengers experience at any transfer stop on the bus line. In the bi-level timetable optimisation problem, the lower level is a transit assignment calculation yielding passengers’ route choice...

  8. Dose optimisation in single plane interstitial brachytherapy

    DEFF Research Database (Denmark)

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette H

    2006-01-01

    on the       regularity of the implant, such that the benefit of optimisation was       larger for irregular implants. OI and HI correlated strongly with target       volume limiting the usability of these parameters for comparison of dose       plans between patients. CONCLUSIONS: Dwell time optimisation significantly...

  9. Hydroxyapatite Fibers: A Review of Synthesis Methods

    Science.gov (United States)

    Qi, Mei-Li; He, Kun; Huang, Zhen-Nan; Shahbazian-Yassar, Reza; Xiao, Gui-Yong; Lu, Yu-Peng; Shokuhfar, Tolou

    2017-08-01

    Hydroxyapatite (HA) exhibits excellent biocompatibility, bioactivity, osteoconductivity, non-toxicity and so on, making it a perfect candidate for biomedical applications. However, HA is not qualified to be used in load-bearing sites due to its poor flexural strength and fracture toughness. Design, synthesis and application of fibrous HA is a promising strategy to overcome the inherent brittleness. This review provides a brief description of HA and hydroxyapatite fiber (HAF), then introduces different synthesis methods of HAF and highlights the inherent merits and drawbacks involved in each method. Finally, the future perspectives in this active research area are given. The purpose of this review is to acquaint the reader with this promising new field of biomaterials research and with emphasis on recent techniques to obtain continuous, uniform and long HAF.

  10. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  11. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  12. Topology Optimisation for Coupled Convection Problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe

    This thesis deals with topology optimisation for coupled convection problems. The aim is to extend and apply topology optimisation to steady-state conjugate heat transfer problems, where the heat conduction equation governs the heat transfer in a solid and is coupled to thermal transport in a sur......This thesis deals with topology optimisation for coupled convection problems. The aim is to extend and apply topology optimisation to steady-state conjugate heat transfer problems, where the heat conduction equation governs the heat transfer in a solid and is coupled to thermal transport...... in a surrounding uid, governed by a convection-diffusion equation, where the convective velocity field is found from solving the isothermal incompressible steady-state Navier-Stokes equations. Topology optimisation is also applied to steady-state natural convection problems. The modelling is done using stabilised...... finite elements, the formulation and implementation of which was done partly during a special course as prepatory work for this thesis. The formulation is extended with a Brinkman friction term in order to facilitate the topology optimisation of fluid flow and convective cooling problems. The derived...

  13. Structural and mechanical study of the sintering effect in hydroxyapatite doped with iron oxide

    Energy Technology Data Exchange (ETDEWEB)

    Filho, F.P.; Nogueira, R.E.F.Q. [Metallurgical and Materials Engineering Department, Federal University of Ceara, Campus do Pici, 714 Block, 60455-760 Fortaleza, Ceara (Brazil); Graca, M.P.F.; Valente, M.A. [Physics Department (I3N), Aveiro University (Portugal); Sombra, A.S.B. [Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Department of Physics, Federal University of Ceara-Campus do Pici, Postal Code 6030, 60455-760 Fortaleza, Ceara (Brazil)], E-mail: sombra@ufc.br; Silva, C.C. [Physics Department (I3N), Aveiro University (Portugal); Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Department of Physics, Federal University of Ceara-Campus do Pici, Postal Code 6030, 60455-760 Fortaleza, Ceara (Brazil)

    2008-10-01

    Calcium phosphates are very important for applications in medicine due to their properties such as biocompatibility and bioactivity. In order to improve their properties, substitution of calcium with other ions has been proposed. Partial substitution of calcium by different ions has been made as a way to improve the properties of the calcium phosphates and also to allow new applications of apatites in medicine. In this work, hydroxyapatite [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}-HAP], prepared by high-energy dry milling (20 h), was mixed with different amounts of iron oxide (0.5, 1, 2.5 and 5 wt%). The mixtures were calcinated at 900 deg. C for 5 h with a heating rate of 3 deg. C/min in an attempt to introduce the iron oxide in the HAP structure. Small discs (12.5 mm o) were uniaxially pressed under a load of 2 t for 2 min. The pellets were sintered at 1000, 1200 and 1300 deg. C for 5 h in air. The main purpose of this work is to study why the iron oxide concentration and the heat treatment of the samples change the microhardness of the obtained ceramics. The sintered samples were characterized by X-ray diffraction (XRD), Vickers Microhardness and scanning electron microscopy (SEM)

  14. Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

    Science.gov (United States)

    Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

    2017-12-01

    Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

  15. Kinetics of calcium binding to dental biofilm bacteria.

    Science.gov (United States)

    Leitão, Tarcísio Jorge; Cury, Jaime Aparecido; Tenuta, Livia Maria Andaló

    2018-01-01

    Dental biofilm bacteria can bind calcium ions and release them during a pH drop, which could decrease the driving force for dental demineralization (i.e. hydroxyapatite dissolution) occurring at reduced pHs. However, the kinetics of this binding and release is not completely understood. Here we validated a method to evaluate the kinetics of calcium binding and release to/from Streptococcus mutans, and estimated the importance of this reservoir as a source of ions. The kinetics of calcium binding was assessed by measuring the amount of bound calcium in S. mutans Ingbrit 1600 pellets treated with PIPES buffer, pH 7.0, containing 1 or 10 mM Ca; for the release kinetics, bacterial pellets previously treated with 1 mM or 10 mM Ca were exposed to the calcium-free or 1 mM Ca PIPES buffer, pH 7.0, for up to 60 min. Binding and release curves were constructed and parameters of kinetics were calculated. Also, calcium release was assessed by exposing pellets previously treated with calcium to a pH 5.0 buffer for 10 min. Calcium binding to bacteria was concentration-dependent and rapid, with maximum binding reached at 5 min. On the other hand, calcium release was slower, and according to the calculations, would never be complete in the groups pretreated with 10 mM Ca. Decreasing pH from 7.0 to 5.0 caused a release of calcium able to increase the surrounding fluid calcium concentration in 2 mM. The results suggest that dental biofilm bacteria may act as a calcium reservoir, rapidly binding ions from surrounding fluids, releasing them slowly at neutral pH and promptly during a pH drop.

  16. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    Directory of Open Access Journals (Sweden)

    Rajan Choudhary

    2015-06-01

    Full Text Available The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7 using eggshell biowaste (as calcium source, magnesium nitrate and tetraethyl orthosilicate (TEOS as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesium silicate was carried out by powder X-ray diffraction (XRD, Fourier transform infrared (FTIR and scanning electron microscopy (SEM techniques. Calcium magnesium silicate crystallite size was observed in nano regime which can effectively mimic natural bone apatite composition. In-vitro bioactivity was investigated by immersing calcium magnesium silicate pellet in simulated body fluid (SBF for three weeks. Results show effective deposition of crystallized hydroxyapatite (HAP layer on its surface and predicting its possibilities for applications in hard tissue regeneration.

  17. Atomic structure of intracellular amorphous calcium phosphate deposits.

    Science.gov (United States)

    Betts, F; Blumenthal, N C; Posner, A S; Becker, G L; Lehninger, A L

    1975-01-01

    The radial distribution function calculated from x-ray diffraction of mineralized cytoplasmic structures isolated from the hepatopancreas of the blue crab (Callinectes sapidus) is very similar to that previously found for synthetic amorphous calcium phosphate. Both types of mineral apparently have only short-range atomic order, represented as a neutral ion cluster of about 10 A in longest dimension, whose probable composition is expressed by the formula Ca9(PO4)6. The minor differences observed are attributed to the presence in the biological mineral of significant amounts of Mg-2+ and ATP. Synthetic amorphous calcium phosphate in contact with a solution containing an amount of ATP equivalent to that of the biological mineral failed to undergo conversion to the thermodynamically more stable hydroxyapatite. The amorphous calcium phosphate of the cytoplasmic mineral granules is similarly stable, and does not undergo conversion to hydroxyapatite, presumably owing to the presence of ATP and Mg-2+, known in inhibitors of the conversion process. The physiological implications of mineral deposits consisting of stabilized calcium phosphate ion clusters are discussed. PMID:1056015

  18. Complications associated with pegging hydroxyapatite orbital implants.

    Science.gov (United States)

    Jordan, D R; Chan, S; Mawn, L; Gilberg, S; Dean, T; Brownstein, S; Hill, V E

    1999-03-01

    Prior studies of hydroxyapatite orbital implant complications have primarily focused on complications of the implant itself with only occasional mention of the complications associated with the peg system. This in part may be because of a low rate of pegging and, thus, a small sample size to evaluate. Therefore, a full range of complications that can occur with pegging has not been presented. The objective of this study was to determine the complications associated with pegging and to discuss ways to manage them. Retrospective, noncomparative case series. The authors analyzed all of the complications associated with pegging 165 of a possible 275 hydroxyapatite implants implanted by 2 surgeons over 7 years. The following data were recorded: type of surgery performed, size of implant used, type of hydroxyapatite used, peg system used, time of pegging, follow-up duration, problems encountered, and treatment. Sixty-two (37.5%) of the 165 patients who had pegged implants were found to have problems with their pegs. Twenty-one (33.8%) of the 62 patients with peg problems had more than 1 peg-related problem. Complications associated with pegging included discharge (37%; 23 of 62), pyogenic granulomas (30.6%; 19 of 62), peg falling out (29%; 18 of 62), poor transfer of movement (11.2%; 7 of 62), clicking (11.2%; 7 of 62), conjunctiva overgrowing peg (4.8%; 3 of 62), poor-fitting sleeve (4.8%; 3 of 62), part of sleeve shaft visible (4.8%; 3 of 62), peg drilled on an angle (4.8%; 3 of 62), hydroxyapatite visible around peg hole (3.2%; 2 of 62), peg drilled off-center (3.2%; 2 of 62), popping peg (3.2%; 2 of 62), and excess movement of peg (3.2%; 2 of 62). The most serious complication occurring in two individuals (3.2%) was implant infection requiring implant removal. There are several potential complications that can occur after pegging the hydroxyapatite implant. These problems are generally of a minor nature but often require additional patient visits that would not

  19. Silica enhanced formation of hydroxyapatite nanocrystals in simulated body fluid (SBF) at 37 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Sadjadi, M.S., E-mail: m.s.sadjad@gmail.com [Department of Chemistry, Sciences and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Ebrahimi, H.R. [Department of Chemistry, Sciences and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Meskinfam, M. [Department of Chemistry, Tonekabon Branch, Islamic Azad University, Tonekabon (Iran, Islamic Republic of); Zare, K. [Department of Chemistry, University of Shahid Beheshti, Eveen Tehran (Iran, Islamic Republic of)

    2011-10-17

    Highlights: {yields} We report on fast formation of hexagonal nanocrystals of calcium hydroxyapatite (HA) in silica-containing simulated body fluid solution at 37 deg. C. {yields} Bioactivity and biodegradability of TCP precursor have been confirmed by the dissolution of TCP and formation of a bone like layer of new HA nanoparticles outside of the precursor after 24 h soaking in SBF solution. {yields} Successive nucleation and formation of tiny hexagonal HA nanoplates and nanorods have been confirmed by TEM results after 24 h soaking of TCP in silica-containing BSF solution. - Abstract: The chemical modification of implant (prosthesis) surfaces is being investigated worldwide for improving the fixation of orthopaedic and dental implants. The main goal in this surface modification approach is to achieve a faster bone growth and chemical bonding of the implant to the newly generated and/or remodeled bone. In this work, we report fast formation of hexagonal nanocrystals of calcium hydroxyapatite (HA) in simulated body fluid (SBF, inorganic components of human blood plasma) solutions at 37 deg. C, using calcium phosphate (TCP) and sodium silicate as precursors. Characterization and chemical analysis of the synthesized powders were performed by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated enhanced nucleation and formation of bone like layer of HA nanocrystals at the surface of TCP nanoparticles and occurrence of HA nanocrystals during 24 h soaking of TCP in SBF solution containing silica ions. The average size of a nanoparticle, using Scherrer formula, was found to be 18.2 nm.

  20. Electric field-assisted formation of organically modified hydroxyapatite (ormoHAP) spheres in carboxymethylated gelatin gels.

    Science.gov (United States)

    Heinemann, C; Heinemann, S; Kruppke, B; Worch, H; Thomas, J; Wiesmann, H P; Hanke, T

    2016-10-15

    A biomimetic strategy was developed in order to prepare organically modified hydroxyapatite (ormoHAP) with spherical shape. The technical approach is based on electric field-assisted migration of calcium ions and phosphate ions into a hydrogel composed of carboxymethylated gelatin. The electric field as well as the carboxymethylation using glucuronic acid (GlcA) significantly accelerates the mineralization process, which makes the process feasible for lab scale production of ormoHAP spheres and probably beyond. A further process was developed for gentle separation of the ormoHAP spheres from the gelatin gel without compromising the morphology of the mineral. The term ormoHAP was chosen since morphological analyses using electron microscopy (SEM, TEM) and element analysis (EDX, FT-IR, XRD) confirmed that carboxymethylated gelatin molecules use to act as organic templates for the formation of nanocrystalline HAP. The hydroxyapatite (HAP) crystals self-organize to form hollow spheres with diameters ranging from 100 to 500nm. The combination of the biocompatible chemical composition and the unique structure of the nanocomposites is considered to be a useful basis for future applications in functionalized degradable biomaterials. A novel bioinspired mineralization process was developed based on electric field-assisted migration of calcium and phosphate ions into biochemically carboxymethylated gelatin acting as organic template. Advantages over conventional hydroxyapatite include particle size distribution and homogeneity as well as achievable mechanical properties of relevant composites. Moreover, specifically developed calcium ion or phosphate ion release during degradation can be useful to adjust the fate of bone cells in order to manipulate remodeling processes. The hollow structure of the spheres can be useful for embedding drugs in the core, encapsulated by the highly mineralized outer shell. In this way, controlled drug release could be achieved, which enables

  1. Hydroxyapatite does not improve the outcome of a bipolar hemiarthroplasty.

    NARCIS (Netherlands)

    Meijerink, H.J.; Gardeniers, J.W.M.; Buma, P.; Lemmens, J.A.M.; Schreurs, B.W.

    2004-01-01

    In a one-surgeon study the clinical and radiographic results of 30 cementless bipolar hip prostheses in 24 patients younger than 55 years were evaluated. Eleven noncoated prostheses (Noncoated Group) and 19 hydroxyapatite-coated prostheses (Hydroxyapatite Group) were compared after a mean followup

  2. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  3. Polishing and whitening properties of toothpaste containing hydroxyapatite.

    Science.gov (United States)

    Niwa, M; Sato, T; Li, W; Aoki, H; Aoki, H; Daisaku, T

    2001-03-01

    Toothpastes containing hydroxyapatite (HA-toothpaste) have demonstrated efficacy in preventing caries, treating hypersensitivity and curing periodontal diseases, however, their effects on whitening teeth have not been investigated. In this study, the polishing and whitening properties of hydroxyapatite contained toothpastes were evaluated in a combined experimental and clinical study. The polishing properties were evaluated in artificial teeth by polishing with different toothpastes, while the brightening and whitening properties were examined in volunteers using two colorimeters with two specially made fiberscopes. The results revealed that the addition of hydroxyapatite to toothpaste did not alter its polishing properties, while it did result in a marked increase in tooth-whiting. It was also found that the brightening and whitening properties increased as the amount of hydroxyapatite in the toothpaste increased. It is concluded that toothpaste containing hydroxyapatite are effective at whitening tooth and that whitening was not due to their polishing effect on tooth surface. Copyright 2001 Kluwer Academic Publishers

  4. Hydroxyapatite nanoparticles: electrospinning and calcination of hydroxyapatite/polyvinyl butyral nanofibers and growth kinetics

    NARCIS (Netherlands)

    Zakaria, S.M.; Zein, S.H. Sharif; Othman, M.R.; Jansen, J.A.

    2013-01-01

    Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600 degrees C. The diameter of the fiber was

  5. Nano-hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Alejandra [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Gonzalez, Jerson [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Garcia-Pineres, Alfonso [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica, 2060 (Costa Rica); Montero, Mavis L. [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Centro de Ciencia e Ingenieria en Materiales (CICIMA), Universidad de Costa Rica, 2060 (Costa Rica)

    2011-06-15

    The properties of porous silicon make it an interesting material for biological applications. However, porous silicon is not an appropriate surface for cell growth. Surface modification is an alternative that could afford a bioactive material. In this work, we report a method to yield materials by modification of the porous silicon surface with hydroxyapatite of nanometric dimensions, produced using an electrochemical process and coated on macroporous silicon substrates by cathodic bias. The chemical nature of the calcium phosphate deposited on the substrates after the experimental process and the amount of cell growth on these surfaces were characterized. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Optimisation Modelling of Efficiency of Enterprise Restructuring

    Directory of Open Access Journals (Sweden)

    Yefimova Hanna V.

    2014-03-01

    Full Text Available The article considers issues of optimisation of the use of resources directed at restructuring of a shipbuilding enterprise, which is the main prerequisite of its efficiency. Restructuring is considered as a process of complex and interconnected change in the structure of assets, liabilities, enterprise functions, initiated by dynamic environment, which is based on the strategic concept of its development and directed at increase of efficiency of its activity, which is expressed in the growth of cost. The task of making a decision to restructure a shipbuilding enterprise and selection of a specific restructuring project refers to optimisation tasks of prospective planning. Enterprise resources that are allocated for restructuring serve as constraints of the mathematical model. Main criteria of optimisation are maximisation of pure discounted income or minimisation of expenditures on restructuring measures. The formed optimisation model is designed for assessment of volumes of attraction of own and borrowed funds for restructuring. Imitation model ensures development of cash flows. The task solution is achieved on the basis of the complex of interrelated optimisation and imitation models and procedures on formation, selection and co-ordination of managerial decisions.

  7. Optimisation of Investment Resources at Small Enterprises

    Directory of Open Access Journals (Sweden)

    Shvets Iryna B.

    2014-03-01

    Full Text Available The goal of the article lies in the study of the process of optimisation of the structure of investment resources, development of criteria and stages of optimisation of volumes of investment resources for small enterprises by types of economic activity. The article characterises the process of transformation of investment resources into assets and liabilities of the balances of small enterprises and conducts calculation of the structure of sources of formation of investment resources in Ukraine at small enterprises by types of economic activity in 2011. On the basis of the conducted analysis of the structure of investment resources of small enterprises the article forms main groups of criteria of optimisation in the context of individual small enterprises by types of economic activity. The article offers an algorithm and step-by-step scheme of optimisation of investment resources at small enterprises in the form of a multi-stage process of management of investment resources in the context of increase of their mobility and rate of transformation of existing resources into investments. The prospect of further studies in this direction is development of a structural and logic scheme of optimisation of volumes of investment resources at small enterprises.

  8. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vladescu, A., E-mail: alinava@inoe.ro [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Braic, M. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Azem, F. Ak [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Buca-Izmir (Turkey); Titorencu, I. [Institute of Cellular Biology and Pathology Nicolae Simionescu of the Romanian Academy, 8 B.P.Hasdeu, Bucharest (Romania); Braic, V. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Pruna, V. [Institute of Cellular Biology and Pathology Nicolae Simionescu of the Romanian Academy, 8 B.P.Hasdeu, Bucharest (Romania); Kiss, A. [National Institute for Optoelectronics, 409 Atomistilor Str., Magurele (Romania); Parau, A.C.; Birlik, I. [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Buca-Izmir (Turkey)

    2015-11-01

    Highlights: • Hydroxyapatite has been produced at temperature from 400 to 800 °C by magnetron sputtering. • Hydroxyapatite crystallinity is improved by increasing substrate temperature. • The increase of substrate temperature resulted in corrosion resistance increasing. • The coating shows high growth of the osteosarcoma cells over a wide temperature range. - Abstract: Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  9. Recent Developments in Suspension Plasma Sprayed Titanium Oxide and Hydroxyapatite Coatings

    Science.gov (United States)

    Jaworski, R.; Pawlowski, L.; Pierlot, C.; Roudet, F.; Kozerski, S.; Petit, F.

    2010-01-01

    The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO2 and Ca5(PO4)3OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 μm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.

  10. Development of nanocomposites based on hydroxyapatite/sodium alginate: Synthesis and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, M.; Meenakshisundaram, N.; Rajendran, V., E-mail: veerajendran@gmail.com

    2011-05-15

    In this study, a novel method was used to produce a nanostructured composite consisting of hydroxyapatite and sodium alginate by varying the composition of sodium alginate. The structure, morphology, simulated body fluid response and mechanical properties of the synthesised nanocomposites were characterised. From X-ray diffraction analysis, an increase in crystallite size and degree of crystallinity with an increase in the composition of sodium alginate up to 1.5 wt.% was observed. Further, it was found to decrease with an increase in the composition of sodium alginate. A notable peak shift from 1635 to 1607 cm{sup -1} and 1456 to 1418 cm{sup -1} in the Fourier transform infrared spectra of the nanocomposite was observed towards the lower wave number side when compared with pure hydroxyapatite. It reveals a strong interaction between the positively charged calcium (Ca{sup 2+}) and the negatively charged carboxyl group (COO{sup -}) in sodium alginate. Transmission electron microscopy images of pure hydroxyapatite showed a short nanorod-like morphology with an average particle size of 13 nm. Bioresorbability of the samples was observed by immersing them in simulated body fluid medium for 14 days to evaluate the changes in pH and Ca{sup 2+} ion strength. Microhardness shows an increasing trend with an increase in the composition of sodium alginate from 1.5 to 3.0 wt.%, which is similar to that in the density. - Research Highlights: {yields} We have prepared nanohydroxyapatite/sodium alginate as a composite. {yields} Effect of sodium alginate on the properties of nanohydrroxyapatite has been studied. {yields} The sodium alginate ranges from 0 to 3.75 wt.% has been used. {yields} Composites show improved biological and mechanical properties.

  11. A solid-state NMR investigation of the structure of nanocrystalline hydroxyapatite.

    Science.gov (United States)

    Jäger, Christian; Welzel, Thea; Meyer-Zaika, Wolfgang; Epple, Matthias

    2006-06-01

    Nanocrystalline hydroxyapatite (HAp) prepared by a precipitation route was investigated. The X-ray diffraction (XRD) powder patterns of the elongated nanocrystals with a typical diameter of about 10 nm and length of 30-50 nm (by transmission electron microscopy (TEM)) revealed the presence of HAp with significantly broadened XRD reflections. However, Ca deficiency was found, as the Ca/P ratio was 1.5 only (so-called calcium-deficient hydroxyapatite (CDHA)), and not 1.67. This Ca deficiency of nanocrystalline HAp is explained using NMR. It is shown unambiguously that (i) the nanocrystals consist of a crystalline core and a (disordered) surface region with a relative phosphate content of about 1:1, (ii) the crystalline core is HAp, and (iii) the surface region is dominated by hydrogen phosphate anions (with no hydroxyapatite-like structural motif) and structural water (hydrate). From the relative phosphate content and taking into account the crystal shape, the thickness of the surface layer along the main crystal axis could be estimated to be about 1 nm, and the average chemical composition of the surface layer has been determined. Finally, a Ca/P ratio of 1.52 was estimated from the NMR data that compares well with the value of 1.51 from chemical analysis. The important consequences are that the surface of nanocrystalline HAp has nothing in common with the bulk composition and that the chemistry of such materials (e.g. the binding of protein molecules to phosphate surfaces) must be reconsidered. 2006 John Wiley & Sons, Ltd.

  12. In vitro study of matrix surface properties of porous granulated calcium phosphate ceramic materials made in Russia.

    Science.gov (United States)

    Chissov, V I; Sviridova, I K; Sergeeva, N S; Kirsanova, V A; Achmedova, S A; Filiushin, M M; Barinov, S M; Fadeeva, I V; Komlev, V S; Smirnov, V V

    2008-04-01

    We performed in vitro screening of monophasic (hydroxyapatite, beta-tricalcium phosphate, carbonate-substituted hydroxyapatite with 0.59 and 5.9 wt% substitution with CO(3)(2-)) and biphasic (hydroxyapatite-tricalcium phosphate with various percentage of the components 80/20, 60/40, 20/80, silicon-substituted hydroxyapatite with 0.79 wt% SiO(2)) porous granulated ceramics composed of calcium phosphate powders synthesized by methods of heterophasic interaction of reagents and precipitation from aqueous solutions using MTT test and cultured human fibroblasts. Acute toxicity of materials (24-h incubation with cell culture) and matrix properties (3, 5, 7, 14, 18, 21, 28 days in culture) were evaluated. We selected a batch of materials obtained by precipitation from aqueous solutions, which were non-toxic and were characterized by good matrix properties (for cells). Biphasic ceramics with hydroxyapatite-tricalcium phosphate ratio of 80/20 exhibited best characteristics, and ceramics on the basis of silicon-substituted hydroxyapatite showed moderate characteristics.

  13. Synthesis of hydroxyapatite from biogenic wastes

    Directory of Open Access Journals (Sweden)

    Teerawat Laonapakul

    2015-09-01

    Full Text Available Hydroxyapatite (HAp is a major component of human bone, teeth and hard tissue. It is one of only a few bioactive materials. Since HAp is the most widely used ceramic biomaterial, various techniques have been developed to synthesize HAp. In recent years, the use of natural biogenic structures and materials for medical proposes has been motivated by limitations in producing synthetic materials. This article mainly focuses on the use of biogenic wastes to prepare HAp. These include bio-wastes, marine corals, eggshells, seashells and bio-membranes. In the present review, useful information about HAp preparation methodologies has been summarized for further research and development.

  14. Self-optimising control of sewer systems

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Montero-Castro, Ignacio; Mollerup, Ane Loft

    The design of sewer system control is a complex task given the large size of the sewer networks, the transient dynamics of the water flows and the stochastic nature of rainfall. This contribution presents a generic methodology for the design of a self-optimising controller in sewer systems....... The definition of an optimal performance was carried out by through a two-stage optimisation (stochastic and deterministic) to take into account both the overflow during the current rain event as well as the expected overflow, given the probability of a future rain event. The methodology is successfully applied...

  15. Topology Optimisation of Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Thike Aye Min

    2016-01-01

    Full Text Available Wireless sensor networks are widely used in a variety of fields including industrial environments. In case of a clustered network the location of cluster head affects the reliability of the network operation. Finding of the optimum location of the cluster head, therefore, is critical for the design of a network. This paper discusses the optimisation approach, based on the brute force algorithm, in the context of topology optimisation of a cluster structure centralised wireless sensor network. Two examples are given to verify the approach that demonstrate the implementation of the brute force algorithm to find an optimum location of the cluster head.

  16. Topology optimisation of natural convection problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Aage, Niels; Andreasen, Casper Schousboe

    2014-01-01

    This paper demonstrates the application of the density-based topology optimisation approach for the design of heat sinks and micropumps based on natural convection effects. The problems are modelled under the assumptions of steady-state laminar flow using the incompressible Navier-Stokes equations...... coupled to the convection-diffusion equation through the Boussinesq approximation. In order to facilitate topology optimisation, the Brinkman approach is taken to penalise velocities inside the solid domain and the effective thermal conductivity is interpolated in order to accommodate differences...... for designing heat sink geometries cooled by natural convection and micropumps powered by natural convection. Copyright © 2013 John Wiley & Sons, Ltd....

  17. Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative "autocatalytic" electroless coprecipitation route.

    Science.gov (United States)

    Oliveira, J M; Costa, S A; Leonor, I B; Malafaya, P B; Mano, J F; Reis, R L

    2009-02-01

    A developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the "autocatalytic" electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20-500 microm. Furthermore, the Fourier transform infra-red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X-ray diffraction pattern of composite scaffolds demonstrated that calcium-phosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% +/- 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the water-uptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired, as in the case of bone tissue-engineering scaffolding applications.

  18. [Structural features of ectopic bone-like tissue in porous hydroxyapatite blocks].

    Science.gov (United States)

    Hattori, Shigetaka

    2008-06-01

    Calcium phosphate ceramics are widely used as bone substitutes because of their favorable biocompatibility and osteoconductivity. Some studies have reported that porous hydroxyapatite (HA), with its special structure, implanted at ectopic (non-bone) sites, exhibits osteoinductive activity. However, few studies have examined the detailed ultrastructure of mineralized tissue formed in biomaterials like HA. Therefore, it is important to examine whether the mineralized tissue exhibits structural characteristics of normal bone tissue. Thus, in this study, we subcutaneously implanted hydroxyapatite blocks (5 x 5 x 7 mm) into the backs of adult dogs, and performed detailed morphological examination of the bone-like tissue formed, which showed a lamellar structure. Immunohistochemical staining revealed that the matrix fibers of the bone-like tissue were mainly composed of type I collagen. The pattern of crystal deposition in matrix fibers and the structure of osteoblast-, osteocyte-, bone-lining-, and osteoclast-like cells were similar to those of normal bone tissue and osteogenic cells, respectively. These results indicate that cellular events observed in normal bone formation and remodeling occur in bone-like tissue as well, and suggest that bone-like tissue in HA blocks is very similar to bone tissue.

  19. New composite materials based on alginate and hydroxyapatite as potential carriers for ascorbic acid.

    Science.gov (United States)

    Ilie, Andreia; Ghiţulică, Cristina; Andronescu, Ecaterina; Cucuruz, Andrei; Ficai, Anton

    2016-08-30

    The purpose of this article was to obtain prolonged drug release systems in which the drug (ascorbic acid) to reach intact the target area in an environment that is able to control the administration of the active component by chemical or physiological pathways. As support for drug, it was used a material based on calcium phosphate - hydroxyapatite and a natural polymer - alginate, since it is one of the most investigated composite materials for medical applications due to its positive response to biological testing: bioactivity, biocompatibility and osteoconductivity. Three composites with different ratios between alginate and hydroxyapatite were obtained: (a) Alg/HA/AA 1:1 (the mass ratio between Alg and HA being of 1:1), (b) Alg/HA/AA 1:3 (Alg:HA mass ratio of 1:3) and (c) Alg/HA/AA 3:1 (Alg:HA mass ratio of 3:1). The synthesized materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and to observe the drug release process, UV-vis spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  1. Effect of aging temperature on formation of sol-gel derived fluor-hydroxyapatite nanoparticles.

    Science.gov (United States)

    Joughehdoust, S; Behnamghader, A; Jahandideh, R; Manafi, S

    2010-04-01

    Synthetic hydroxyapatite (HA) has been recognized as one of the most important bone substitute materials in orthopaedics and dentistry over past few decades because of its chemical and biological similarity to the mineral phase of human bone. One solution for reduction the solubility of HA in biological environments is replacing F- by OH in HA structure and forming fluor-hydroxyapatite (FHA) solid solution. In this paper, FHA nanoparticles were successfully synthesized by a sol-gel method. Also, the influence of aging temperature on formation of FHA powder was studied. Equimolar solutions of calcium nitrate tetrahydrate, triethyl phosphite and ammonium fluoride in ethanol were used as Ca, P and F precursors. After aging at different temperatures, the synthesized powders were heat treated at 550 degrees C. The powders were investigated with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), energy dispersive analysis of X-ray (EDAX) and zetasizer measurement. The results of XRD proved the presence of fluorapatite (FA) and HA in all samples. In addition, the formation of FHA was confirmed by FT-IR results. XRD studies also showed that the crystallites were in nanometric scale. At the same time, this result was in good agreement with the result of zetasizer analysis.

  2. Obtaining of biodegradable polylactide films and fibers filled hydroxyapatite for medical purposes

    Energy Technology Data Exchange (ETDEWEB)

    Lytkina, D. N., E-mail: darya-lytkina@yandex.ru; Shapovalova, Y. G., E-mail: elena.shapovalova@ro.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru; Kurzina, I. A., E-mail: kurzina99@mail.ru; Filimoshkin, A. G., E-mail: filag05@rambler.ru [National Research Tomsk State University 36, Lenina Avenue, Tomsk, 634050 (Russian Federation)

    2015-11-17

    Relevance of the work is due to the need for new materials that are used in medicine (orthopedics, surgery, dentistry, and others) as a substitute for natural bone tissue injuries, fractures, etc. The aim of presented work is developing of a method of producing biocompatible materials based on polyesters of hydroxycarboxylic acids and calcium phosphate ceramic (hydroxyapatite, HA) with homogeneous distribution of the inorganic component. Bioactive composites based on poly-L-lactide (PL) and hydroxyapatite with homogeneous distribution were prepared. The results of scanning electron microscopy confirm homogeneous distribution of the inorganic filler in the polymer matrix. The positive effect of ultrasound on the homogeneity of the composites was determined. The rate of hydrolysis of composites was evaluated. The rate of hydrolysis of polylactide as an individual substance is 7 times lower than the rate of hydrolysis of the polylactide as a part of the composite. It was found that materials submarines HA composite and do not cause a negative response in the cells of the immune system, while contributing to anti-inflammatory cytokines released by cells.

  3. Synthesis and Characterization of Collagen Scaffolds Reinforced by Eggshell Derived Hydroxyapatite for Tissue Engineering.

    Science.gov (United States)

    Padmanabhan, Sanosh Kunjalukkal; Salvatore, Luca; Gervaso, Francesca; Catalano, Massimo; Taurino, Antonietta; Sannino, Alessando; Licciulli, Antonio

    2015-01-01

    In this work, we synthesized porous nanohydroxyapatite/collagen composite scaffold (nHA-COL), which resemble extracellular matrices in bone and cartilage tissues. Nano hydroxyapatite (nHA) was successfully nucleated in to the collagen matrix using hen eggshell as calcium biogenic source. Porosity was evaluated by apparent and theoretical density measurement. Porosity of all scaffolds was in the range of 95-98%. XRD and TEM analyses show the purity and size of nucleated HA around 10 nm and selected area electron diffraction (SAED) analysis reveals the polycrystalline nature of nucleated HA. SEM analysis reveals (i) all the scaffolds have interconnected pores with an average pore diameter of 130 micron and (ii) aggregates of hydroxyapatite were strongly embedded in the collagen matrix for both composite scaffolds compared with pure collagen scaffold. EDS analysis shows the Ca/P stoichiometric ratio around 1.67 and FTIR reveals the chemical interaction between the collagen molecule and HA particles. The testing of mechanical properties evidenced that incorporation of HA resulted in up to a two-fold increase in compressive modulus with high reinforcement level (-7 kPa for 50HA-50COL) compared to pure collagen scaffold.

  4. The role of amino acids in hydroxyapatite mineralization.

    Science.gov (United States)

    Tavafoghi, M; Cerruti, M

    2016-10-01

    Polar and charged amino acids (AAs) are heavily expressed in non-collagenous proteins (NCPs), and are involved in hydroxyapatite (HA) mineralization in bone. Here, we review what is known on the effect of single AAs on HA precipitation. Negatively charged AAs, such as aspartic acid, glutamic acid (Glu) and phosphoserine are largely expressed in NCPs and play a critical role in controlling HA nucleation and growth. Positively charged ones such as arginine (Arg) or lysine (Lys) are heavily involved in HA nucleation within extracellular matrix proteins such as collagen. Glu, Arg and Lys intake can also increase bone mineral density by stimulating growth hormone production. In vitro studies suggest that the role of AAs in controlling HA precipitation is affected by their mobility. While dissolved AAs are able to inhibit HA precipitation and growth by chelating Ca(2+) and PO4(3-) ions or binding to nuclei of calcium phosphate and preventing their further growth, AAs bound to surfaces can promote HA precipitation by attracting Ca(2+) and PO4(3-) ions and increasing the local supersaturation. Overall, the effect of AAs on HA precipitation is worth being investigated more, especially under conditions closer to the physiological ones, where the presence of other factors such as collagen, mineralization inhibitors, and cells heavily influences HA precipitation. A deeper understanding of the role of AAs in HA mineralization will increase our fundamental knowledge related to bone formation, and could lead to new therapies to improve bone regeneration in damaged tissues or cure pathological diseases caused by excessive mineralization in tissues such as cartilage, blood vessels and cardiac valves. © 2016 The Author(s).

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

    Science.gov (United States)

    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

  6. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

  7. Optimisation of interventional cardiology procedures; Optimisation des procedures en cardiologie interventionnelle

    Energy Technology Data Exchange (ETDEWEB)

    Bar, Olivier [SELARL, Cardiologie Interventionnelle Imagerie Cardiaque - CIIC, 8, place de la Cathedrale - 37042 Tours (France)

    2011-07-15

    Radiation-guided procedures in interventional cardiology include diagnostic and/or therapeutic procedures, primarily coronary catheterization and coronary angioplasty. Application of the principles of radiation protection and the use of optimised procedures are contributing to dose reduction while maintaining the radiological image quality necessary for performance of the procedures. The mandatory training in patient radiation protection and technical training in the use of radiology devices mean that implementing continuous optimisation of procedures is possible in practice. This optimisation approach is the basis of patient radiation protection; when associated with the wearing of protective equipment it also contributes to the radiation protection of the cardiologists. (author)

  8. A comparison between optimisation algorithms for metal forming processes

    NARCIS (Netherlands)

    Bonte, M.H.A.; Do, D.T.D.; Fourment, L.; van den Boogaard, Antonius H.; Huetink, Han; Juster, N.; Rosochowski, A.

    2006-01-01

    Coupling optimisation algorithms to Finite Element (FEM) simulations is a very promisingway to achieve optimal metal forming processes. However, many optimisation algorithms exist and it is notclear which of these algorithms to use. This paper compares an efficient Metamodel Assisted

  9. Study of hydroxyapatite behaviour during sintering of 316L steel

    Directory of Open Access Journals (Sweden)

    A. Szewczyk-Nykiel

    2010-07-01

    Full Text Available 316L stainless steel – hydroxyapatite composite biomaterials with different hydroxyapatite weight fraction in the composite wereinvestigated. Hydroxyapatite (HAp – Ca10(PO46(OH2 is well known biomaterial. HAp reveals excellent chemical and biological affinitywith bony tissues. On the other hand hydroxyapatite shows low mechanical properties. The combination of very good biocompatibility of hydroxyapatite and high mechanical properties of stainless steel seems to be a good solution. In presented research natural originhydroxyapatite and 316L austenitic stainless steel were used. In this work, metal-ceramics composites were fabricated by the powdermetallurgy technology (involving pressing and sintering process. Sintering was carried out at 1250oC in hydrogen atmosphere. Thedensity, porosity and hardness were investigated. Metallographic microscope and SEM were carried out in order to investigate themicrostructure. The horizontal NETZSCH DIL 402E dilatometer was used to evaluate the dimensional changes and phenomena occurringduring sintering. The research displayed that physical properties of sintered 316L-HAp composites decrease with increase ofhydroxyapatite content. Microstructure of investigated composites consists of austenitic and probably inclusions of hydroxyapatite andheterogeneous eutectic occurring on the grain boundaries. It was shown that amount of hydroxyapatite in the powder mixtures influencethe dimensional changes occurring during sintering.

  10. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

    Science.gov (United States)

    Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. © 2013.

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

    Science.gov (United States)

    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

  12. RF magnetron sputtering of a hydroxyapatite target: A comparison study on polytetrafluorethylene and titanium substrates

    Science.gov (United States)

    Surmenev, Roman A.; Surmeneva, Maria A.; Grubova, Irina Yu.; Chernozem, Roman V.; Krause, Bärbel; Baumbach, Tilo; Loza, Kateryna; Epple, Matthias

    2017-08-01

    A pure hydroxyapatite (HA) target was used to prepare the biocompatible coating of HA on the surface of a polytetrafluorethylene (PTFE) substrate, which was placed on the same substrate holder with technically pure titanium (Ti) in the single deposition runs by radio-frequency (RF) magnetron sputtering. The XPS, XRD and FTIR analyses of the obtained surfaces showed that for all substrates, instead of the HA coating deposition, the coating of a mixture of calcium carbonate and calcium fluoride was grown. According to SEM investigations, the surface of PTFE was etched, and the surface topography of uncoated Ti was preserved after the depositions. The FTIR results reveal no phosphate bonds; only calcium tracks were observed in the EDX-spectra on the surface of the coated PTFE substrates. Phosphate oxide (V), which originated from the target, could be removed using a vacuum pump system, or no phosphate-containing bonds could be formed on the substrate surface because of the severe substrate bombardment process, which prevented the HA coating deposition. The observed results may be connected with the surface re-sputtering effect of the growing film by high-energy negatively charged ions (most probably oxygen or fluorine), which are accelerated in the cathode dark sheath.

  13. C-terminal Amidation of an Osteocalcin-derived Peptide Promotes Hydroxyapatite Crystallization*

    Science.gov (United States)

    Hosseini, Samaneh; Naderi-Manesh, Hossein; Mountassif, Driss; Cerruti, Marta; Vali, Hojatollah; Faghihi, Shahab

    2013-01-01

    Genesis of natural biocomposite-based materials, such as bone, cartilage, and teeth, involves interactions between organic and inorganic systems. Natural biopolymers, such as peptide motif sequences, can be used as a template to direct the nucleation and crystallization of hydroxyapatite (HA). In this study, a natural motif sequence consisting of 13 amino acids present in the first helix of osteocalcin was selected based on its calcium binding ability and used as substrate for nucleation of HA crystals. The acidic (acidic osteocalcin-derived peptide (OSC)) and amidic (amidic osteocalcin-derived peptide (OSN)) forms of this sequence were synthesized to investigate the effects of different C termini on the process of biomineralization. Electron microscopy analyses show the formation of plate-like HA crystals with random size and shape in the presence of OSN. In contrast, spherical amorphous calcium phosphate is formed in the presence of OSC. Circular dichroism experiments indicate conformational changes of amidic peptide to an open and regular structure as a consequence of interaction with calcium and phosphate. There is no conformational change detectable in OSC. It is concluded that HA crystal formation, which only occurred in OSN, is attributable to C-terminal amidation of a natural peptide derived from osteocalcin. It is also proposed that natural peptides with the ability to promote biomineralization have the potential to be utilized in hard tissue regeneration. PMID:23362258

  14. C-terminal amidation of an osteocalcin-derived peptide promotes hydroxyapatite crystallization.

    Science.gov (United States)

    Hosseini, Samaneh; Naderi-Manesh, Hossein; Mountassif, Driss; Cerruti, Marta; Vali, Hojatollah; Faghihi, Shahab

    2013-03-15

    Genesis of natural biocomposite-based materials, such as bone, cartilage, and teeth, involves interactions between organic and inorganic systems. Natural biopolymers, such as peptide motif sequences, can be used as a template to direct the nucleation and crystallization of hydroxyapatite (HA). In this study, a natural motif sequence consisting of 13 amino acids present in the first helix of osteocalcin was selected based on its calcium binding ability and used as substrate for nucleation of HA crystals. The acidic (acidic osteocalcin-derived peptide (OSC)) and amidic (amidic osteocalcin-derived peptide (OSN)) forms of this sequence were synthesized to investigate the effects of different C termini on the process of biomineralization. Electron microscopy analyses show the formation of plate-like HA crystals with random size and shape in the presence of OSN. In contrast, spherical amorphous calcium phosphate is formed in the presence of OSC. Circular dichroism experiments indicate conformational changes of amidic peptide to an open and regular structure as a consequence of interaction with calcium and phosphate. There is no conformational change detectable in OSC. It is concluded that HA crystal formation, which only occurred in OSN, is attributable to C-terminal amidation of a natural peptide derived from osteocalcin. It is also proposed that natural peptides with the ability to promote biomineralization have the potential to be utilized in hard tissue regeneration.

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

    Science.gov (United States)

    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. © 2014 Wiley Periodicals, Inc.

  16. Electrochemical Processes for the Formation of Hydroxyapatite Powders

    Directory of Open Access Journals (Sweden)

    Adrian Nur

    2014-10-01

    Full Text Available Electrochemical synthesis of hydroxyapatite particles was performed from a homogeneous solution of Na2H2EDTA.2H2O, KH2PO4 and CaCl2 without stirring to investigate the mechanism of hydroxyapa-tite formation. We found that OH- ions generated by water reduction at the cathode play an important role in the formation of hydroxyapatite particles. The OH- ions induce the liberation of Ca2+ ions and the dissociation of phosphoric acid, which serve as the reactants for the formation of hydroxyapatite particles. Two layers with a clear boundary were formed during electrolysis. The upper layer comprises the produced particles and the lower layer is a homogeneous solution. The produced particles were held in the region between the electrodes mainly due to the electrostatic interactions of charged particles in an electric field. The hydroxyapatite particles are agglomerates consisting of spherical particles. Aging the suspension for 24 h after electrolysis leads to the transformation of hydroxyapatite to brushite. Thus, if producing hydroxyapatite is desired, the particles should be continuously removed from the system. This method appears to be promising as a continuous process to produce hydroxyapatite parti-cles using an electrochemical method. © 2014 BCREC UNDIP. All rights reservedReceived: 10th April 2014; Revised: 25th May 2014; Accepted: 27th June 2014How to Cite: Nur, A., Setyawan, H., Widjaja, A., Lenggoro, I.W. (2014. Electrochemical Processes for the Formation of Hydroxyapatite Powders. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 168-175. (doi:10.9767/bcrec.9.3.6686.168-175Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6686.168-175

  17. How does bone sialoprotein promote the nucleation of hydroxyapatite? A molecular dynamics study using model peptides of different conformations.

    Science.gov (United States)

    Yang, Yang; Cui, Qiang; Sahai, Nita

    2010-06-15

    Bone sialoprotein (BSP) is a highly phosphorylated, acidic, noncollagenous protein in bone matrix. Although BSP has been proposed to be a nucleator of hydroxyapatite (Ca(5)(PO(4))(3)OH), the major mineral component of bone, no detailed mechanism for the nucleation process has been elucidated at the atomic level to date. In the present work, using a peptide model, we apply molecular dynamics (MD) simulations to study the conformational effect of a proposed nucleating motif of BSP (a phosphorylated, acidic, 10 amino-acid residue sequence) on controlling the distributions of Ca(2+) and inorganic phosphate (Pi) ions in solution, and specifically, we explore whether a nucleating template for orientated hydroxyapatite could be formed in different peptide conformations. Both the alpha-helical conformation and the random coil structure have been studied, and inorganic solutions without the peptide are simulated as reference. Ca(2+) distributions around the peptide surface and interactions between Ca(2+) and Pi in the presence of the peptide are examined in detail. From the MD simulations, although in some cases for the alpha-helical conformation, we observe that a Ca(2+) equilateral triangle forms around the surface of peptide, which matches the distribution of Ca(2+) ions on the (001) face of the hydroxyapatite crystal, we do not consistently find a stable nucleating template formation in general for either the helical conformation or the random coil structure. Therefore, independent of conformations, the BSP nucleating motif is more likely to help nucleate an amorphous calcium phosphate cluster, which ultimately converts to crystalline hydroxyapatite.

  18. Extending Particle Swarm Optimisers with Self-Organized Criticality

    DEFF Research Database (Denmark)

    Løvbjerg, Morten; Krink, Thiemo

    2002-01-01

    Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions.......Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions....

  19. Effect of iron II on hydroxyapatite dissolution and precipitation in vitro.

    Science.gov (United States)

    Delbem, A C B; Alves, K M R P; Sassaki, K T; Moraes, J C S

    2012-01-01

    The aim of this study was to evaluate the effect of iron II on the dissolution and precipitation of synthetic hydroxyapatite (HA). HA powder was suspended in solutions of iron (0.84 µg/ml, Fe0.84; 18.0 µg/ml, Fe18; 70.0 µg/ml, Fe70), fluoride (1,100 µg/ml, F1,100), and deionized water and submitted to pH cycling. After pH cycling, the samples were analyzed by infrared spectroscopy and X-ray diffraction. The concentrations of fluoride, calcium, phosphorus, and iron were also analyzed. The data were submitted to ANOVA, and analyzed by Tukey's test (p 0.05). There was an increase in Fe concentration in the HA directly related to the Fe concentration of the treatment solutions. Results show that the presence of Fe causes the precipitation of apatite with high solubility. Copyright © 2012 S. Karger AG, Basel.

  20. Comparison of crystallinity between natural hydroxyapatite and synthetic cp-Ti /HA coatings

    Directory of Open Access Journals (Sweden)

    Camila Molena de Assis

    2005-06-01

    Full Text Available Commercial purity titanium (cp-Ti, and some of its alloys are important materials in the medical field because of their excellent biocompatibility and mechanical properties. Recently a simple chemical method to induce bioactivity in these inert metallic materials was reported. In this work, the biomimetic chemical process has been used to modify the surface of cp-Ti with the formation of a deposit layer of apatite (a calcium phosphate compound. The main purpose was to study the influence of heat treatment on changes in crystallinity in the deposited phases. X-ray diffraction analysis and scanning electron microscopy showed that the apatite coatings heat treated between 400 and 600 °C were less crystalline, similar to biological apatites. Upon heat treatment at temperatures above 700 °C, the apatite coatings appeared more crystalline, and were a mixture of hydroxyapatite, octacalcium phosphate and magnesium phosphate.

  1. Synthesis, characterization, biocompatibility of hydroxyapatite-natural polymers nanocomposites for dentistry applications.

    Science.gov (United States)

    Chung, Jin-Hwan; Kim, Young Kyung; Kim, Kyo-Han; Kwon, Tae-Yub; Vaezmomeni, Seyede Ziba; Samiei, Mohammad; Aghazadeh, Marzyeh; Davaran, Soodabeh; Mahkam, Mehrdad; Asadi, Ghale; Akbarzadeh, Abolfazl

    2016-01-01

    Hydroxyapatite (HA), the main mineral component of bones and teeth, was synthesized by using the reaction between calcium nitrate tetrahydrate Ca(NO3)2∙4H2O and diammonium hydrogen phosphate (NH4)2HPO4 (DAHP) with a chemical precipitation method. The objective of this study is to utilize novel inorganic-organic nanocomposites for biomedical applications. HA is an inorganic component (75% w) and chitosan, alginate and albumin (Egg white) are organic components of nanocomposites (25% w). Nanocomposites were prepared in deionized water solutions, at room temperature, using a mechanical and magnetic stirrer for 48 h. The microstructure and morphology of sintered n-HAP were tested at different preheating temperature and laser sintering speed with scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).

  2. Atomic force microscopy reveals hydroxyapatite-citrate interfacial structure at the atomic level.

    Science.gov (United States)

    Jiang, Wenge; Pan, Haihua; Cai, Yurong; Tao, Jinhui; Liu, Peng; Xu, Xurong; Tang, Ruikang

    2008-11-04

    An approach to organic-inorganic interfacial structure at the atomic level is a great challenge in the studies of biomineralization. We demonstrate that atomic force microscopy (AFM) is powerful tool to discover the biomineral interface in detail. By using a model system of (100) hydroxyapatite (HAP) face and citrate, it reveals experimentally that only a side carboxylate and a surface calcium ion are involved in the binding effect during the citrate adsorption, which is against the previous understandings by using Langmuir adsorption and computer simulation. Furthermore, the adsorbed citrate molecules can use their free carboxylate and hydroxyl groups to be self-assembled on the HAP surface. AFM examination also finds that the presence of citrate molecules on the HAP crystal faces can enhance the adhesion force of the HAP surface. We suggest that the established AFM method can be used for a precise and direct understanding of biointerfaces at the atomic level.

  3. Bacterial Stress and Osteoblast Responses on Graphene Oxide-Hydroxyapatite Electrodeposited on Titanium Dioxide Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Yardnapar Parcharoen

    2017-01-01

    Full Text Available To develop bone implant material with excellent antibacterial and biocompatible properties, nanotubular titanium surface was coated with hydroxyapatite (HA and graphene oxide (GO. Layer-by-layer deposition was achieved by coating HA on an anodic-grown titanium dioxide nanotube array (ATi with electrolytic deposition, followed by coating with GO using anodic-electrophoretic deposition. The antibacterial activity against both Gram-negative (Escherichia coli and Gram-positive (Staphylococcus aureus bacteria was determined based on the percentage of surviving bacteria and the amount of ribonucleic acid (RNA leakage and correlated with membrane disruption. The oxidative stress induced in both strains of bacteria by GO was determined by cyclic voltammetry and is discussed. Importantly, the antibacterial GO coatings on HA-ATi were not cytotoxic to preosteoblasts and promoted osteoblast proliferation after 5 days and calcium deposition after 21 days in standard cell culture conditions.

  4. Ultrastructure study of hydroxyapatite precipitation on ceramic surfaces in dog model

    Energy Technology Data Exchange (ETDEWEB)

    Xin Renlong [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong (China); Leng Yang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong (China)], E-mail: meleng@ust.hk; Wang Ning [Department of Physics, Hong Kong University of Science and Technology, Hong Kong (China)

    2008-12-01

    Calcium phosphate (Ca-P) minerals were precipitated on porous alpha-tricalcium phosphate ({alpha}-TCP) after implantation in dog muscles for four weeks. Scanning electron microscopy (SEM) examinations indicated that the Ca-P precipitates exhibited flattened-hexagonal rod shapes. Electron diffraction revealed that the rod-like precipitates were hydroxyapatite (HA) elongated in the c-axis. High-resolution transmission electron microscopy (HRTEM) was used to analyze the ultrastructures of the precipitates. We found the evidence of octacalcium phosphate (OCP) structure embedding in a few rod-like HA precipitates. The orientation relationship of OCP/HA revealed in the precipitates was consistent with observations of the solid-state OCP/HA transformation in synthetic specimens, i.e., OCP (010)//HA (01-bar 0) and OCP (001)//HA (001-bar )

  5. The effects of electrolytes on the rates of hydroxyapatite formation at 25 and 38 degrees C.

    Science.gov (United States)

    Brown, P W; Fulmer, M

    1996-07-01

    The effects of electrolytes on the rates of hydroxyapatite (HAp) formation at 25 and 38 degrees C were investigated. Solutions were selected to contain ions in common with HAp lattice ions or to contain ions capable of substituting into HAp. The effects of phosphate, calcium, chloride, and fluoride were studied in particular. The reactants from which HAp was formed were a mixture of the particulate solids CaHPO4 and Ca4(PO4)2O. These reactants were proportioned to form the calcium deficient composition Ca9HPO4(PO4)5OH at complete reaction. The rates of HAp formation were examined by determining rates of heat liberation at 25 and 38 degrees C using isothermal calorimetry and by analyzing the variations in solution chemistry. HAp formation initially occurs by a mechanism which is interfacially controlled. However, because the reactants dissolve incongruently, HAp overgrows these particles and eventually the conversion becomes diffusionally controlled. The presence of electrolytes influences HAp formation but in differing ways. Solutions containing phosphate salts initially accelerate the rate of HAp formation by reducing the incongruency of the CaHPO4 dissolution. Sodium fluoride accelerates reaction by improving the crystallinity of the apatite overgrowths as a result of fluoride incorporation into the HAp, thereby making them less effective as diffusion barriers. Calcium chloride solutions tend to reduce the proportion of HAp formed prior to the onset of the diffusionally controlled reactions. Although the reactants used were proportioned to produce calcium-deficient HAp at complete reaction, no evidence was obtained to indicate the uptake of calcium and chloride from CaCl2 solutions to form a chloroapatite having a Ca/P ratio > 1.5.

  6. Histologic analysis of a retrieved hydroxyapatite-coated femoral prosthesis

    DEFF Research Database (Denmark)

    Søballe, K; Gotfredsen, K; Brockstedt-Rasmussen, H

    1991-01-01

    A hydroxyapatite-coated hip hemi-prosthesis was retrieved from a 98-year-old osteoporotic woman 12 weeks after implantation. Histologic analysis revealed bone and fibrous tissue almost evenly distributed around the surface of the implant circumference. Quantitative histologic analysis showed...... that 48% of the hydroxyapatite surface was covered by bone. Fibrous tissue covered 30% of the prosthetic surface, and 20% of the surface had no tissue coverage. Scanning electron microscopy showed direct contact without any clear boundary between the newly formed bone and the hydroxyapatite ceramic....

  7. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  8. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  9. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  10. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  11. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  12. CMPLServer - An open source approach for distributed and grid optimisation

    OpenAIRE

    Steglich, Mike

    2016-01-01

    This paper describes CMPLServer, an XML-RPC-based web service for distributed and grid optimisation for CMPL (Coin|Coliop Mathematical Programming Language) which is a mathematical programming language as well as a system for mathematical programming and optimisation of linear optimisation problems.

  13. Application of Surpac and Whittle Software in Open Pit Optimisation ...

    African Journals Online (AJOL)

    Application of Surpac and Whittle Software in Open Pit Optimisation and Design. ... This paper studies the Surpac and Whittle software and their application in designing an optimised pit. Exploration ... During the optimisation, a total of 82 optimal pit outlines were generated using the 3D Lerchs-Grossmann algorithm. Pit 36 ...

  14. Optimising Shovel-Truck Fuel Consumption using Stochastic ...

    African Journals Online (AJOL)

    Optimising the fuel consumption and truck waiting time can result in significant fuel savings. The paper demonstrates that stochastic simulation is an effective tool for optimising the utilisation of fossil-based fuels in mining and related industries. Keywords: Stochastic, Simulation Modelling, Mining, Optimisation, Shovel-Truck ...

  15. Particle Swarm Optimisation with Spatial Particle Extension

    DEFF Research Database (Denmark)

    Krink, Thiemo; Vesterstrøm, Jakob Svaneborg; Riget, Jacques

    2002-01-01

    In this paper, we introduce spatial extension to particles in the PSO model in order to overcome premature convergence in iterative optimisation. The standard PSO and the new model (SEPSO) are compared w.r.t. performance on well-studied benchmark problems. We show that the SEPSO indeed managed...... to keep diversity in the search space and yielded superior results....

  16. Thermodynamic optimisation of a heat exchanger

    NARCIS (Netherlands)

    Cornelissen, Rene; Hirs, Gerard

    1999-01-01

    The objective of this paper is to show that for the optimal design of an energy system, where there is a trade-off between exergy saving during operation and exergy use during construction of the energy system, exergy analysis and life cycle analysis should be combined. An exergy optimisation of a

  17. Expression optimisation of recombinant α-Larabinofuranosidase ...

    African Journals Online (AJOL)

    Expression optimisation of recombinant α-Larabinofuranosidase from Aspergillus niger ATCC 120120 in Pichia pastoris and its biochemical characterisation. NI Alias, NM Mahadi, NM Mahadi, AMA Murad, AMA Murad, FDA Bakar, FDA Bakar, A Rabu, A Rabu, RM Illias, RM Illias ...

  18. Water distribution systems design optimisation using metaheuristics ...

    African Journals Online (AJOL)

    The topic of multi-objective water distribution systems (WDS) design optimisation using metaheuristics is investigated, comparing numerous modern metaheuristics, including several multi-objective evolutionary algorithms, an estimation of distribution algorithm and a recent hyperheuristic named AMALGAM (an evolutionary ...

  19. OPTIMISATION OF COMPRESSIVE STRENGTH OF PERIWINKLE ...

    African Journals Online (AJOL)

    In this paper, a regression model is developed to predict and optimise the compressive strength of periwinkle shell aggregate concrete using Scheffe's regression theory. The results obtained from the derived regression model agreed favourably with the experimental data. The model was tested for adequacy using a student ...

  20. Federated optimisation of kinetic analysis problems.

    Science.gov (United States)

    Dowson, Nicholas; Baker, Charles; Thomas, Paul; Smith, Jye; Puttick, Simon; Bell, Christopher; Salvado, Olivier; Rose, Stephen

    2017-01-01

    Positron Emission Tomography (PET) data is intrinsically dynamic, and kinetic analysis of dynamic PET data can substantially augment the information provided by static PET reconstructions. Yet despite the insights into disease that kinetic analysis offers, it is not used clinically and seldom used in research beyond the preclinical stage. The utility of PET kinetic analysis is hampered by several factors including spatial inconsistency within regions of homogeneous tissue and relative computational expense when fitting complex models to individual voxels. Even with sophisticated algorithms inconsistencies can arise because local optima frequently have narrow basins of convergence, are surrounded by relatively flat (uninformative) regions, have relatively low-gradient valley floors, or combinations thereof. Based on the observation that cost functions for individual voxels frequently bear some resemblance to each-other, this paper proposes the federated optimisation of the individual kinetic analysis problems within a given image. This approach shares parameters proposed during optimisation with other, similar voxels. Federated optimisation exploits the redundancy typical of large medical images to improve the optimisation residuals, computational efficiency and, to a limited extent, image consistency. This is achieved without restricting the formulation of the kinetic model, resorting to an explicit regularisation parameter, or limiting the resolution at which parameters are computed. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  1. Optimising fuel treatments over time and space

    Science.gov (United States)

    Woodam Chung; Greg Jones; Kurt Krueger; Jody Bramel; Marco Contreras

    2013-01-01

    Fuel treatments have been widely used as a tool to reduce catastrophic wildland fire risks in many forests around the world. However, it is a challenging task for forest managers to prioritise where, when and how to implement fuel treatments across a large forest landscape. In this study, an optimisation model was developed for long-term fuel management decisions at a...

  2. Topology Optimisation for Coupled Convection Problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Andreasen, Casper Schousboe; Aage, Niels

    the widely used Brinkman-penalisation approach to fluid topology optimisation [2] combined with suitable interpolation functions for thermal conductivity. The Method of Moving Asymptotes (MMA) is used and density filtering is applied in order to ensure a minimum lengthscale. The results are generated using...

  3. Optimisation of phenolic compound biosynthesis in grape ...

    African Journals Online (AJOL)

    steve

    http://www.academicjournals.org/AJB. African Journal of Biotechnology. Full Length Research Paper. Optimisation of phenolic compound biosynthesis in grape (Bogazkere Cv.) callus culture. Mehmet KARAASLAN1*, Mustafa OZDEN2, Hasan VARDİN1 and Fatih Mehmet YILMAZ1. 1Harran University, Faculty of Agriculture, ...

  4. Benchmarks for dynamic multi-objective optimisation

    CSIR Research Space (South Africa)

    Helbig, M

    2013-06-01

    Full Text Available of dynamic multi-objective optimisation algorithms (DMOAs) are highlighted. In addition, new DMOO benchmark functions with complicated Pareto-optimal sets (POSs) and approaches to develop DMOOPs with either an isolated or deceptive Pareto-optimal front (POF...

  5. Sol-gel synthesis and spectrometric structural evaluation of strontium substituted hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, A. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Balossier, G. [INSERM ERM 0203, Laboratoire de Microscopie Electronique Analytique, University of Reims, 21, Rue Clement Ader, 51685 Reims (France); Torres, P.; Michel, J. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Ferreira, J.M.F., E-mail: jmf@cv.ua.pt [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2009-04-30

    Investigations of the electronic structures of substituted strontium apatites were carried out by using X-ray photo electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction technique (XRD) has been used to determine the structural parameters. Electron microprobe microanalysis technique was used to estimate the elemental concentrations in each substituted apatite material. The present work aims at studying the changes in the electronic structure of Sr{sub 5}(PO{sub 4}){sub 3}OH (Sr-HAP) upon isomorphic substitution by F and Cl at the OH site of apatite and Sr by Na at trans Sr-HAP. The ion exchange between Na{sup +} in sodium alginate and aqueous Ca{sup 2+} was important for the preparation of calcium hydroxyapatite. In contrast, the reaction of sodium alginate with the mixture of Na{sub 4}P{sub 2}O{sub 7} and aqueous Sr{sup 2+} afforded strontium hydroxyapatite at the specific ratio. The structure of calcium and strontium phosphates prepared from the sol-gel process evidently depended on the amount of sodium alginate introduced into the mixture of Na{sub 4}P{sub 2}O{sub 7} and the corresponding divalent cations. The findings have ensured that substitution of Sr-HAP by Na enhances the binding energy of O and Sr core levels. It was also noticed that the same substitution decreases the binding energy of P 2s-level. These observations point out to a decrease in the electron density at P and an increase in the electron density at O in Sr atoms.

  6. PNIPAAM modified mesoporous hydroxyapatite for sustained osteogenic drug release and promoting cell attachment

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tao [The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China); Tan, Lei [Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); Cheng, Ning; Yan, Qi; Zhang, Yu-Feng [The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China); Liu, Chuan-Jun, E-mail: cjliu@whu.edu.cn [Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); Shi, Bin, E-mail: shibin_dentist@126.com [The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079 (China)

    2016-05-01

    This work presented a sustained release system of simvastatin (SIM) based on the mesoporous hydroxyapatite (MHA) capped with poly(N-isopropylacrylamide) (PNIPAAM). The MHA was prepared by using cetyltrimethylammonium bromide (CTAB) as a template and the modified PNIPAAM layer on the surface of MHA was fabricated through surface-initiated atom transfer radical polymerization (SI-ATRP). The SIM loaded MHA-PNIPAAM showed a sustained release of SIM at 37 °C over 16 days. The bone marrow mesenchymal stem cell (BMSC) proliferation was assessed by cell counting kit-8 (CCK-8) assay, and the osteogenic differentiation was evaluated by alkaline phosphatase (ALP) activity and Alizarin Red staining. The release profile showed that the release of SIM from MHA-SIM-PNIPAAM lasted 16 days and the cumulative amount of released SIM was almost seven-fold than MHA-SIM. Besides, SIM loaded MHA-PNIPAAM exhibited better performance on cell proliferation, ALP activity, and calcium deposition than pure MHA due to the sustained release of SIM. The quantity of ALP in MHA-SIM-PNIPAAM group was more than two fold than pure MHA group at 7 days. Compared to pure MHA, better BMSC attachment on PNIPAAM modified MHA was observed using fluorescent microscopy, indicating the better biocompatibility of MHA-PNIPAAM. - Highlights: • PNIPAAM modified mesoporous hydroxyapatite (MHA) was fabricated by SI-ATRP. • SIM loaded MHA-PNIPAAM continually released SIM in effect concentration for 16 days. • MHA-SIM-PNIPAAM behaved well on cell proliferation, ALP activity and calcium deposition.

  7. Process intensification for the production of hydroxyapatite nanoparticles

    Science.gov (United States)

    Castro, Filipa Juliana Fernandes

    Precipitation processes are widely used in chemical industry for the production of particulate solids. In these processes, the chemical and physical nature of synthesized particles is of key importance. The traditional stirred tank batch reactors are affected by non-uniform mixing of reactants, often resulting in broad particle size distribution. The main objective of this thesis was to apply meso and microreactors for the synthesis of hydroxyapatite (HAp) nanoparticles under near-physiological conditions of pH and temperature, in order to overcome the limitations associated with stirred tank batch reactors. Meso and microreactors offer unique features in comparison with conventional chemical reactors. Their high surface-to-volume ratio enables enhanced heat and mass transfer, as well as rapid and efficient mixing. In addition to low consumption of reagents, meso and microreactors are usually operated in continuous flow, making them attractive tools for high throughput experimentation. Precipitation of HAp was first studied in a stirred tank batch reactor, mixing being assured by a novel metal stirrer. HAp was synthetized by mixing diluted aqueous solutions of calcium hydroxide and orthophosphoric acid at 37 °C. After process optimization, a suspension of HAp nanoparticles with pH close to 7 was obtained for a mixing molar ratio Ca/P=1.33. The precipitation process was characterized by three stages: precipitation of amorphous calcium phosphate, transformation of amorphous calcium phosphate into HAp and growth of HAp crystals. The reaction system was further characterized based on equilibrium equations. The resolution of the system, which was possible with the knowledge of three process variables (temperature, pH and calcium concentration), allowed identifying and quantifying all the chemical species present in solution. The proposed model was validated by comparing the experimental and theoretical conductivity. Precipitation of HAp was then investigated in a meso

  8. Effects of serum protein on ionic exchange between culture medium and microporous hydroxyapatite and silicate-substituted hydroxyapatite.

    Science.gov (United States)

    Guth, Katharina; Campion, Charlie; Buckland, Tom; Hing, Karin A

    2011-10-01

    It has been proposed that one of the underlying mechanisms contributing to the bioactivity of osteoinductive or osteoconductive calcium phosphates involves the rapid dissolution and net release of calcium and phosphate ions from the matrix as alternatively a precursor to subsequent re-precipitation of a bone-like apatite at the surface and/or to facilitate ion exchange in biochemical processes. In order to confirm and evaluate ion release from sintered hydroxyapatite (HA) and to examine the effect of silicate substitution into the HA lattice on ion exchange under physiological conditions we monitored Ca(2+), PO(4)(3-) and SiO(4)(4-) levels in Earl's minimum essential medium (E-MEM) in the absence (serum-free medium, SFM) or presence (complete medium, C-MEM) of foetal calf serum (FCM), with both microporous HA or 2.6 wt% silicate-substituted HA (SA) sintered discs under both static and semi-dynamic (SD) conditions for up to 28 days. In SFM, variation in Ca(2+) ion concentration was not observed with either disc chemistry or culture conditions. In C-MEM, Ca(2+) ions were released from SA under static and SD conditions whereas with HA Ca(2+) was depleted under SD conditions. PO(4)(3-) depletion occurred in all cases, although it was greater in C-MEM, particularly under SD conditions. SiO(4)(4-) release occurred from SA irrespective of medium or culture conditions but a sustained release only occurred in C-MEM under SD conditions. In conclusion we showed that under physiological conditions the reservoir of exchangeable ions in both HA and SA in the absence of serum proteins is limited, but that the presence of serum proteins facilitated greater ionic exchange, particularly with SA. These observations support the hypothesis that silicate substitution into the HA lattice facilitates a number of ionic interactions between the material and the surrounding physiological environment, including but not limited to silicate ion release, which may play a key role in determining

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

    Science.gov (United States)

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

    2008-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  12. Calcium phosphate bioceramics prepared from wet chemically precipitated powders

    Directory of Open Access Journals (Sweden)

    Kristine Salma

    2010-03-01

    Full Text Available In this work calcium phosphates were synthesized by modified wet chemical precipitation route. Contrary to the conventional chemical precipitation route calcium hydroxide was homogenized with planetary mill. Milling calcium oxide and water in planetary ball mill as a first step of synthesis provides a highly dispersed calcium hydroxide suspension. The aim of this work was to study the influence of main processing parameters of wet chemical precipitation synthesis product and to control the morphology, phase and functional group composition and, consequently, thermal stability and microstructure of calcium phosphate bioceramics after thermal treatment. The results showed that it is possible to obtain calcium phosphates with different and reproducible phase compositions after thermal processing (hydroxyapatite [HAp], β-tricalcium phosphate [β-TCP] and HAp/β-TCP by modified wet-chemical precipitation route. The β-TCP phase content in sintered bioceramics samples is found to be highly dependent on the changes in technological parameters and it can be controlled with ending pH, synthesis temperature and thermal treatment. Pure, crystalline and highly thermally stable (up to 1300°C HAp bioceramics with homogenous grainy microstructure, grain size up to 200–250 nm and high open porosity can be successfully obtained by powder synthesized at elevated synthesis temperature of 70°C and stabilizing ending pH at 9.

  13. Phosphate Adsorption from Membrane Bioreactor Effluent Using Dowex 21K XLT and Recovery as Struvite and Hydroxyapatite.

    Science.gov (United States)

    Nur, Tanjina; Loganathan, Paripurnanda; Kandasamy, Jaya; Vigneswaran, Saravanamuthu

    2016-03-03

    Discharging phosphate through wastewaters into waterways poses a danger to the natural environment due to the serious risks of eutrophication and health of aquatic organisms. However, this phosphate, if economically recovered, can partly overcome the anticipated future scarcity of phosphorus (P) resulting from exhaustion of natural phosphate rock reserves. An experiment was conducted to determine the efficiency of removing phosphate from a membrane bioreactor effluent (pH 7.0-7.5, 20, 35 mg phosphate/L) produced in a water reclamation plant by adsorption onto Dowex 21K XLT ion exchange resin and recover the phosphate as fertilisers. The data satisfactorily fitted to Langmuir adsorption isotherm with a maximum adsorption capacity of 38.6 mg · P/g. The adsorbed phosphate was quantitatively desorbed by leaching the column with 0.1 M NaCl solution. The desorbed phosphate was recovered as struvite when ammonium and magnesium were added at the molar ratio of phosphate, ammonium and magnesium of 1:1:1 at pH 9.5. Phosphate was also recovered from the desorbed solution as hydroxyapatite precipitate by adding calcium hydroxide to the solution at a phosphate to calcium molar ratio of 1:2 at pH 7.0. The P contents of struvite and hydroxyapatite produced were close to those of the respective commercial phosphate fertilisers.

  14. Carbonate Hydroxyapatite and Silicon-Substituted Carbonate Hydroxyapatite: Synthesis, Mechanical Properties, and Solubility Evaluations

    Directory of Open Access Journals (Sweden)

    L. T. Bang

    2014-01-01

    Full Text Available The present study investigates the chemical composition, solubility, and physical and mechanical properties of carbonate hydroxyapatite (CO3Ap and silicon-substituted carbonate hydroxyapatite (Si-CO3Ap which have been prepared by a simple precipitation method. X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray fluorescence (XRF spectroscopy, and inductively coupled plasma (ICP techniques were used to characterize the formation of CO3Ap and Si-CO3Ap. The results revealed that the silicate (SiO44- and carbonate (CO32- ions competed to occupy the phosphate (PO43- site and also entered simultaneously into the hydroxyapatite structure. The Si-substituted CO3Ap reduced the powder crystallinity and promoted ion release which resulted in a better solubility compared to that of Si-free CO3Ap. The mean particle size of Si-CO3Ap was much finer than that of CO3Ap. At 750°C heat-treatment temperature, the diametral tensile strengths (DTS of Si-CO3Ap and CO3Ap were about 10.8±0.3 and 11.8±0.4 MPa, respectively.

  15. Macroporous hydroxyapatite bioceramics by solid freeform fabrication: towards custom implants

    CSIR Research Space (South Africa)

    Richter, PW

    1999-08-01

    Full Text Available structure that would be impossible to make by conventional manufacturing methods. Application of this technology to the manufacture of macro porous hydroxyapatite bio ceramics for bone substitute applications is discussed. A new design is described...

  16. Physical characterization of hydroxyapatite porous scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, S., E-mail: smsilva@ineb.up.pt [INEB - Instituto de Engenharia Biomedica, Divisao de Biomateriais, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto (Portugal); Universidade do Porto, Faculdade de Engenharia, Departamento de Engenharia Metalurgica e Materiais, Porto (Portugal); Rodriguez, M.A.; Pena, P.; De Aza, A.H.; De Aza, S. [Instituto de Ceramica y Vidrio, CSIC, 28049-Cantoblanco, Madrid (Spain); Ferraz, M.P. [INEB - Instituto de Engenharia Biomedica, Divisao de Biomateriais, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto (Portugal); Faculdade de Ciencias da Saude da Universidade Fernando Pessoa, Rua Carlos da Maia, 296, 4200-150 Porto (Portugal); Monteiro, F.J. [INEB - Instituto de Engenharia Biomedica, Divisao de Biomateriais, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto (Portugal); Universidade do Porto, Faculdade de Engenharia, Departamento de Engenharia Metalurgica e Materiais, Porto (Portugal)

    2009-06-01

    The present study refers to the preparation and characterization of porous hydroxyapatite scaffolds to be used as matrices for bone regeneration or as specific release vehicles. Ceramics are widely used for bone tissue engineering purposes and in this study, hydroxyapatite porous scaffolds were produced using the polymer replication method. Polyurethane sponges were used as templates and impregnated with a ceramic slurry at different ratios, and sintered at 1300 deg. C following a specific thermal cycle. The characteristics of the hydroxyapatite porous scaffolds and respective powder used as starting material, were investigated by using scanning electron microscopy, particle size distribution, X-ray diffraction, Fourier transformed infrared spectroscopy and compressive mechanical testing techniques. It was possible to produce highly porous hydroxyapatite scaffolds presenting micro and macropores and pore interconnectivity.

  17. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  18. Tuning the Degradation Rate of Calcium Phosphate Cements by Incorporating Mixtures of Polylactic-co-Glycolic Acid Microspheres and Glucono-Delta-Lactone Microparticles

    NARCIS (Netherlands)

    Sariibrahimoglu, K.; An, J.; Oirschot, B.A.J.A. van; Nijhuis, A.W.G.; Eman, R.M.; Alblas, J.; Wolke, J.G.C.; Beucken, J.J.J.P van den; Leeuwenburgh, S.C.G.; Jansen, J.A.

    2014-01-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has

  19. Antifungal Applications of Ag-Decorated Hydroxyapatite Nanoparticles

    OpenAIRE

    Zamperini, C. A.; André, R. S.; Longo, V. M.; Mima, E. G.; Vergani, C. E.; Machado, A. L.; Varela, J. A.; Longo, E.

    2013-01-01

    Pure hydroxyapatite (HA) and hydroxyapatite decorated with silver (HA@Ag) nanoparticles were synthesized and characterized. The antifungal effect of HA@Ag nanoparticles in a distilled water solution was evaluated against Candida albicans. The origin of the antifungal activity of the HA@Ag is also discussed. The results obtained showed that the HA nanorod morphology remained the same with Ag ions decorations on the HA structure which were deposited in the form of nanospheres. Interaction where...

  20. A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Jinfa, E-mail: jinfa.ming@gmail.com [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Zuo, Baoqi, E-mail: bqzuo@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China)

    2012-11-15

    A novel electrospinning of silk fibroin/hydroxyapatite hybrid nanofibers with different composition ratios was performed with methanoic acid as a spinning solvent. The silk fibroin/hydroxyapatite hybrids containing up to 30% hydroxyapatite nanoparticles could be electrospun into the continuous fibrous structure. The electrospun silk fibroin/hydroxyapatite hybrid nanofibers showed bigger diameter and wider diameter distribution than pure silk fibroin nanofibers, and the average diameter gradually increased from 95 to 582 nm. At the same time, the secondary structure of silk fibroin/hydroxyapatite nanofibers was characterized by X-ray diffraction, Fourier transform infrared analysis, and DSC measurement. Comparing with the pure silk fibroin nanofibers, the crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. X-ray diffraction results demonstrated the hydroxyapatite crystalline nature remained as evidenced from the diffraction planes (002), (211), (300), and (202) of the hydroxyapatite crystallites, which was also confirmed by Fourier transform infrared analysis. The thermal behavior of hybrid nanofibers exhibited the endothermic peak of moisture evaporation ranging from 86 to 113 Degree-Sign C, and the degradation peak at 286 Degree-Sign C appeared. The SF/HAp nanofibers mats containing 30% HAp nanoparticles showed higher breaking tenacity and extension at break for 1.1688 {+-} 0.0398 MPa and 6.55 {+-} 1.95%, respectively. Therefore, the electrospun silk fibroin/hydroxyapatite hybrid nanofibers should be provided potentially useful options for the fabrication of biomaterial scaffolds for bone tissue engineering. -- Highlights: Black-Right-Pointing-Pointer The novel SF/HAp nanofibers were directly prepared by electrospinning method. Black-Right-Pointing-Pointer The nanofiber diameter had significant related to the content of HAp. Black-Right-Pointing-Pointer The crystal structure of silk fibroin was mainly amorphous structure in

  1. Hardness and microplasticity of nanocrystalline and amorphous calcium phosphate coatings

    Science.gov (United States)

    Ievlev, V. M.; Kostyuchenko, A. V.; Darinskii, B. M.; Barinov, S. M.

    2014-02-01

    The hardness of thin (1.0-4.0 μm) hydroxyapatite coatings with different structures (nanocrystalline, amorphous-crystalline, and amorphous) grown by rf magnetron sputtering on Ti and Si plates has been studied using the nanoindentation method. All the grown structures are characterized by the strain which has reversible and irreversible components. The hardness of nanocrystalline coatings (about 10 GPa) corresponds to the average hardness of hydroxyapatite single crystals. The structure of nanocrystalline coatings in the indentation zone and outside it has been investigated and changes in the structure under the indenter have been revealed using high-resolution transmission electron microscopy. From a comparison of the hardnesses of coatings with different structures and based on an analysis of the intragranular structure, it has been assumed that the plastic deformation occurs according to a dislocation-free mechanism. The plastic deformation is interpreted in terms of the cluster representation of the hydroxyapatite structure and amorphous calcium phosphates of the same elemental composition and cluster-boundary sliding during the deformation.

  2. Polylactic acid-nanocrystalline carbonated hydroxyapatite (PLA-cHAP) composite: preparation and surface topographical structuring with direct laser writing (DLW)

    CERN Document Server

    Garskaite, Edita; Drienovsky, Marian; Krajcovic, Jozef; Cicka, Roman; Palcut, Marian; Jonusauskas, Linas; Malinauskas, Mangirdas; Stankeviciute, Zivile; Kareiva, Aivaras

    2016-01-01

    The fabrication of polylactic acid (PLA)-carbonated hydroxyapatite (cHAP) composite material from synthesised phase pure nano-cHAP and melted PLA by mechanical mixing at 220-235{\\deg}C has been developed in this study. Topographical structuring of PLA-cHAP composite surfaces was performed by direct laser writing (DLW). Microstructured surfaces and the apatite distribution within the composite and formed grooves were evaluated by optical and scanning electron microscopies. The influence of the dopant concentration as well as the laser power and translation velocity on the composite surface morphology is discussed. The synthesis of carbonated hydroxyapatite (cHAP) nanocrystalline powders via wet chemistry approach from calcium acetate and diammonium hydrogen phosphate precursors together with crosslinking and complexing agents of polyethylene glycol, poly(vinyl alcohol) and triethanolamine is also reported. Thermal decomposition of the gels and formation of nanocrystalline cHAP were evaluated by thermal analysi...

  3. Defect induced asymmetric pit formation on hydroxyapatite.

    Science.gov (United States)

    Kwon, Ki-Young; Wang, Eddie; Chung, Alice; Chang, Neil; Saiz, Eduardo; Choe, Uh-Joo; Koobatian, Maxwell; Lee, Seung-Wuk

    2008-10-07

    Defect sites on bone minerals play a critical role in bone remodeling processes. We investigated single crystal hydroxyapatite (100) surfaces bearing crystal defects under acidic dissolution conditions using real-time in situ atomic force microscopy. At defect sites, surface structure-dependent asymmetric hexagonal etch pits were formed, which dominated the overall dissolution rate. Meanwhile, dissolution from the flat terraces proceeded by stochastic formation of flat bottom etch pits. The resulting pit shapes were intrinsically dictated by the HAP crystal structure. Computational modeling also predicted different step energies associated with different facets of the asymmetric etch pits. Our microscopic observations of HAP dissolution are significant for understanding the effects of local surface structure on the bone mineral remodeling process and provide useful insights for the design of novel therapies for treating osteoporosis and dental caries.

  4. Processing of hydroxyapatite obtained by combustion synthesis

    Directory of Open Access Journals (Sweden)

    M. Canillas

    2017-09-01

    Full Text Available One of the reasons of implants failure are the stress forces appearing in the material–tissue interface due to the differences between their mechanical properties. For this reason, similar mechanical properties to the surrounding tissue are desirable. The synthesis of hydroxyapatite by solution combustion method and its processing have been studied in order to obtain fully dense ceramic bodies with improved mechanical strength. Combustion synthesis provides nanostructured powders characterized by a high surface area to facilitate the following sintering. Moreover, synthesis was conducted in aqueous and oxidizing media. Oxidizing media improve homogenization and increase the energy released during combustion. It gives rise to particles whose morphology and size suggest lower surface energies compared with aqueous media. The obtained powders were sintered by using a controlled sintering rate schedule. Lower surfaces energies minimize the shrinkage during sintering and relative densities measurements and diametral compression test confirm improved densification and consequently mechanical properties.

  5. Novel doped hydroxyapatite thin films obtained by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duta, L. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, 409 Atomistilor Street, Magurele (Romania); Oktar, F.N. [Department of Bioengineering, Faculty of Engineering, Marmara University, Goztepe, Istanbul 34722 (Turkey); Department of Medical Imaging Technics, Vocational School of Health Services, Marmara University, Uskudar, Istanbul 34668 (Turkey); Nanotechnology and Biomaterials Application and Research Centre, Marmara University, Istanbul (Turkey); Stan, G.E. [National Institute of Materials Physics, 105 Bis Atomistilor Street, Magurele (Romania); Popescu-Pelin, G.; Serban, N.; Luculescu, C. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, 409 Atomistilor Street, Magurele (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, 409 Atomistilor Street, Magurele (Romania)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer HA coatings synthesized by pulsed laser deposition. Black-Right-Pointing-Pointer Comparative study of commercial vs. animal origin materials. Black-Right-Pointing-Pointer HA coatings of animal origin were rougher and more adherent to substrates. Black-Right-Pointing-Pointer Animal origin films can be considered as promising candidates for implant coatings. - Abstract: We report on the synthesis of novel ovine and bovine derived hydroxyapatite thin films on titanium substrates by pulsed laser deposition for a new generation of implants. The calcination treatment applied to produce the hydroxyapatite powders from ovine/bovine bones was intended to induce crystallization and to prohibit the transmission of diseases. The deposited films were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. Pull-off adherence and profilometry measurements were also carried out. X-ray diffraction ascertained the polycrystalline hydroxyapatite nature of the powders and films. Fourier transform infrared spectroscopy evidenced the vibrational bands characteristic to a hydroxyapatite material slightly carbonated. The micrographs of the films showed a uniform distribution of spheroidal particulates with a mean diameter of {approx}2 {mu}m. Pull-off measurements demonstrated excellent bonding strength values between the hydroxyapatite films and the titanium substrates. Because of their physical-chemical properties and low cost fabrication from renewable resources, we think that these new coating materials could be considered as a prospective competitor to synthetic hydroxyapatite used for implantology applications.

  6. Novel doped hydroxyapatite thin films obtained by pulsed laser deposition

    Science.gov (United States)

    Duta, L.; Oktar, F. N.; Stan, G. E.; Popescu-Pelin, G.; Serban, N.; Luculescu, C.; Mihailescu, I. N.

    2013-01-01

    We report on the synthesis of novel ovine and bovine derived hydroxyapatite thin films on titanium substrates by pulsed laser deposition for a new generation of implants. The calcination treatment applied to produce the hydroxyapatite powders from ovine/bovine bones was intended to induce crystallization and to prohibit the transmission of diseases. The deposited films were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. Pull-off adherence and profilometry measurements were also carried out. X-ray diffraction ascertained the polycrystalline hydroxyapatite nature of the powders and films. Fourier transform infrared spectroscopy evidenced the vibrational bands characteristic to a hydroxyapatite material slightly carbonated. The micrographs of the films showed a uniform distribution of spheroidal particulates with a mean diameter of ∼2 μm. Pull-off measurements demonstrated excellent bonding strength values between the hydroxyapatite films and the titanium substrates. Because of their physical-chemical properties and low cost fabrication from renewable resources, we think that these new coating materials could be considered as a prospective competitor to synthetic hydroxyapatite used for implantology applications.

  7. Formation of Biomimetic Hydroxyapatite Coating on Titanium Plates

    Directory of Open Access Journals (Sweden)

    Ievgen Volodymyrovych PYLYPCHUK

    2014-09-01

    Full Text Available Hydroxyapatite (HA has long been used as a coating material in the implant industry for orthopedic implant applications. HA is the natural inorganic constituent of bone and teeth. By coating titanium (base material of implant engineering because of its lightness and durability with hydroxyapatite, we can provide higher biocompatibility of titanium implants, according to HA ability to form a direct biochemical bond with living tissues. This article reports a biomimetic approach for coating hydroxyapatite with titanium A method of modifying the surface of titanium by organic modifiers (for creating functional groups on the surface, followed by formation "self-assembled" layer of biomimetic hydroxyapatite in simulated body fluid (SBF. FTIR and XPS confirmed the formation of hydroxyapatite coatings on titanium surface. Comparative study of the formation of HA on the surface of titanium plates modified by different functional groups: Ti(≡OH, Ti/(≡Si-OH and Ti/(≡COOH is conducted. It was found that the closest to natural stoichiometric hydroxyapatite Ca/P ratio was obtained on Ti/(≡COOH samples. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4974

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

    Science.gov (United States)

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

    2014-01-01

    In cementless fixation of metallic prostheses, bony ingrowth onto the implant surface is often promoted by osteoconductive plasma-sprayed hydroxyapatite coatings. The present work explores the use of the innovative High Velocity Suspension Flame Spraying (HVSFS) process to coat Ti substrates with thin homogeneous hydroxyapatite coatings. The HVSFS hydroxyapatite coatings studied were dense, 27-37μm thick, with some transverse microcracks. Lamellae were sintered together and nearly unidentifiable, unlike conventional plasma-sprayed hydroxyapatite. Crystallinities of 10%-70% were obtained, depending on the deposition parameters and the use of a TiO2 bond coat. The average hardness of layers with low (hydroxyapatite, with a Weibull modulus of ≈3.3. During soaking in simulated body fluid, glassy coatings were progressively resorbed and replaced by a new, precipitated hydroxyapatite layer, whereas coatings with 70% crystallinity were stable up to 14days of immersion. The interpretation of the precipitation behaviour was also assisted by surface charge assessments, performed through Z-potential measurements. During in vitro tests, HA coatings showed no cytotoxicity towards the SAOS-2 osteoblast cell line, and surface cell proliferation was comparable with proliferation on reference polystyrene culture plates. © 2013.

  9. Hydroxyapatite Growth Inhibition Effect of Pellicle Statherin Peptides.

    Science.gov (United States)

    Xiao, Y; Karttunen, M; Jalkanen, J; Mussi, M C M; Liao, Y; Grohe, B; Lagugné-Labarthet, F; Siqueira, W L

    2015-08-01

    In our recent studies, we have shown that in vivo-acquired enamel pellicle is a sophisticated biological structure containing a significant portion of naturally occurring salivary peptides. From a functional aspect, the identification of peptides in the acquired enamel pellicle is of interest because many salivary proteins exhibit functional domains that maintain the activities of the native protein. Among the in vivo-acquired enamel pellicle peptides that have been newly identified, 5 peptides are derived from statherin. Here, we assessed the ability of these statherin pellicle peptides to inhibit hydroxyapatite crystal growth. In addition, atomistic molecular dynamics (MD) simulations were performed to better understand the underlying physical mechanisms of hydroxyapatite growth inhibition. A microplate colorimetric assay was used to quantify hydroxyapatite growth. Statherin protein, 5 statherin-derived peptides, and a peptide lacking phosphate at residues 2 and 3 were analyzed. Statherin peptide phosphorylated on residues 2 and 3 indicated a significant inhibitory effect when compared with the 5 other peptides (P hydroxyapatite for phosphopeptides, whereas unphosphorylated peptides interacted weakly with the hydroxyapatite. Our data suggest that the presence of a covalently linked phosphate group (at residues 2 and 3) in statherin peptides modulates the effect of hydroxyapatite growth inhibition. This study provides a mechanism to account for the composition and function of acquired enamel pellicle statherin peptides that will contribute as a base for the development of biologically stable and functional synthetic peptides for therapeutic use against dental caries and/or periodontal disease. © International & American Associations for Dental Research 2015.

  10. Rapid growth of hydroxyapatite nanoparticles using ultrasonic irradiation.

    Science.gov (United States)

    Rouhani, Parvaneh; Taghavinia, Nima; Rouhani, Shohre

    2010-06-01

    A rapid, environmental friendly and low-cost method to prepare hydroxyapatite nanoparticles is proposed. In this method, hydroxyapatite is produced in a sonicated pseudo-body solution. The sonication time was found effective in the formation of the crystalline phase of nanoparticles. In our experimental condition, 15 min sonication resulted in the most pure hydroxyapatite phase. Also it was shown that growth temperature is a crucial factor and hydroxyapatite crystallizes only at 37 degrees C. The particles formed by sonication were generally smaller and more spherical than those obtained without sonication. Sonication increased the hydroxyapatite crystal growth rate up to 5.5 times compared to non-sonication condition. The comparison between the specific surface area of hydroxyapatite nanoparticles obtained by sonication and without sonication demonstrated that sonication increased the specific surface area from 63 m(2)/g to 107 m(2)/g and decreased the size of nanoparticles from 30 nm to 18 nm. Analysis on the pore structure demonstrated that the fractal structures obtained with and without sonication were considerably different. (c) 2010 Elsevier B.V. All rights reserved.

  11. Property Optimisation of EPDM Rubber Composites Using Mathematical and Statistical Strategies

    Directory of Open Access Journals (Sweden)

    Sivaldo Leite Correia

    2017-01-01

    Full Text Available This paper describes a study in which EPDM-based rubber composites were investigated aiming at developing formulations subjected to restrictions on cost and the properties of the material. The contents of components other than calcium carbonate, paraffinic oil, and CBS vulcanising accelerator, as well as additives and processing conditions, were kept constant. Fractional factorial design coupled with computational numerical optimisation was used to minimise the number of mixtures. The results demonstrate that statistical design of experiments and particle swarm optimisation (PSO algorithms are promising methods to design composition variables. Mixture costs as low as 1.92 US$/kg can be achieved in compositions containing, for example, 107 phr of calcium carbonate, 95 phr of paraffinic oil, and 1.13 phr of CBS accelerator. The corresponding composite property-predicted values were 66.8 Shore A for hardness, tensile strength of 7.8 MPa, 570.8% elongation at break, and 23.0% rebound resilience. This demonstrates that, in this way, the desired product with specified characteristics can be comfortably manufactured at minimum cost.

  12. Study of characteristics of a two phase biomaterial hydroxyapatite / β -tricalcium phosphate 60/40 the composition in volume; Estudo de caracterizacao de um biomaterial bifasico hidroxiapatita/fosfato tricalcio - β na composicao 60/40 em volume

    Energy Technology Data Exchange (ETDEWEB)

    Dalmonico, G.M.L.; Passoni, L.; Prandi, R.G.; Camargo, N.H.A.; Gemelli, E., E-mail: gidalmonico@gmail.com [Universidade do Estado de Santa Catarina (CCT/UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas. Programa de Pos-Graduacao em Ciencias e Engenharia de Materiais

    2011-07-01

    This work has developed on the preparation and characterization of the composition of biphasic hydroxyapatite /β-calcium phosphate = 60/40%. The mixture composition was performed using the mechanical fragmentation process in an attrition mill for 1 hour. The powder recovered from the biphasic attrition mill after drying, was subjected to compression, to obtain the specimens, the dimensions of 10mm height and 5mm in diameter. The specimens obtained from compaction were sintered at temperature of 1100 ° C/2h. The recovered material was subjected to sintering studies of characterization: compression, hardness and porosity. The results showed a breakdown voltage greater than 76.27 ± 13.56, higher than the microhardness 572.80 ± 13.31 MPa and the porosity of around 40% by volume. The results of the composition biphasic hydroxyapatite /β-calcium phosphate are encouraging, since the biomaterial presented favorable conditions for biomedical applications in the reconstitution of the bone structure. (author)

  13. On Constructing Ensembles for Combinatorial Optimisation.

    Science.gov (United States)

    Hart, Emma; Sim, Kevin

    2017-01-10

    Although the use of ensemble methods in machine-learning is ubiquitous due to their proven ability to outperform their constituent algorithms, ensembles of optimisation algorithms have received relatively little attention. Existing approaches lag behind machine-learning in both theory and practice, with no principled design guidelines available. In this article, we address fundamental questions regarding ensemble composition in optimisation using the domain of bin-packing as an example. In particular, we investigate the trade-off between accuracy and diversity, and whether diversity metrics can be used as a proxy for constructing an ensemble, proposing a number of novel metrics for comparing algorithm diversity. We find that randomly composed ensembles can outperform ensembles of high-performing algorithms under certain conditions and that judicious choice of diversity metric is required to construct good ensembles. The method and findings can be generalised to any metaheuristic ensemble, and lead to better understanding of how to undertake principled ensemble design.

  14. Buckling optimisation of sandwich cylindrical panels

    Science.gov (United States)

    Abouhamzeh, M.; Sadighi, M.

    2016-06-01

    In this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.

  15. Self-optimising control of sewer systems

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Montero-Castro, I.; Mollerup, Ane Loft

    2013-01-01

    Self-optimising control is a useful concept to select optimal controlled variables from a set of candidate measurements in a systematic manner. In this study, use self-optimizing control tools and apply them to the specific features of sewer systems, e.g. the continuously transient dynamics......, the availability of a large number of measurements, the stochastic and unforeseeable character of the disturbances (rainfall). Using a subcatchment area in the Copenhagen sewer system as a case study we demonstrate, step by step, the formulation of the self-optimising control problem. The final result...... is an improved control structure aimed at optimizing the losses for a given control objective, here the minimization of the combined sewer overflows despite rainfall variations....

  16. Applying the Theory of Optimising Professional Life

    Directory of Open Access Journals (Sweden)

    Lesley Margaret Piko

    2014-12-01

    Full Text Available Glaser (2014 wrote that “the application of grounded theory (GT is a relatively neglected topic” (p. 1 in the literature. Applying GT to purposely intervene and improve a situation is an important adjunct to our knowledge and understanding of GT. A recent workshop of family doctors and general practitioners provides a useful example. The theory of optimising professional life explains that doctors are concerned about sustainment in their career and, to resolve this concern, they implement solutions to optimise their personal situation. Sustainment is a new, overarching concept of three needs: the need for self-care to sustain well-being, the need for work interest to sustain motivation, and the need for income to sustain lifestyle. The objective of the workshop was to empower doctors to reinvent their careers using this theory. Working individually and in small groups, participants were able to analyse a problem and to identify potential solutions.

  17. Studies on calcium phosphate precipitation: effects of metal ions used in dental materials.

    Science.gov (United States)

    Okamoto, Y; Hidaka, S

    1994-12-01

    The effects of 26 metal ions, of which 23 are used in dental materials, on the conversion of amorphous calcium phosphate (ACP) to hydroxyapatite (HAP) in vitro were studied. From the effects on both the rate of HAP transformation and induction time, effects of metal ions were classified into three types; inhibitory (in the order: nickel, tin, cobalt, manganese, copper, zinc, gallium, thallium, molybdenum, cadmium, antimony, magnesium, and mercury); ineffective (cesium, titanium, chromium, iron [ferrous], iridium, palladium, platinum, silver, gold, aluminum, and lead); and stimulatory (iron [ferric] and indium). These results suggest that metal ions used in dental materials may modify the precipitation of oral calcium phosphate.

  18. Treatment planning optimisation in proton therapy

    Science.gov (United States)

    McGowan, S E; Burnet, N G; Lomax, A J

    2013-01-01

    ABSTRACT. The goal of radiotherapy is to achieve uniform target coverage while sparing normal tissue. In proton therapy, the same sources of geometric uncertainty are present as in conventional radiotherapy. However, an important and fundamental difference in proton therapy is that protons have a finite range, highly dependent on the electron density of the material they are traversing, resulting in a steep dose gradient at the distal edge of the Bragg peak. Therefore, an accurate knowledge of the sources and magnitudes of the uncertainties affecting the proton range is essential for producing plans which are robust to these uncertainties. This review describes the current knowledge of the geometric uncertainties and discusses their impact on proton dose plans. The need for patient-specific validation is essential and in cases of complex intensity-modulated proton therapy plans the use of a planning target volume (PTV) may fail to ensure coverage of the target. In cases where a PTV cannot be used, other methods of quantifying plan quality have been investigated. A promising option is to incorporate uncertainties directly into the optimisation algorithm. A further development is the inclusion of robustness into a multicriteria optimisation framework, allowing a multi-objective Pareto optimisation function to balance robustness and conformity. The question remains as to whether adaptive therapy can become an integral part of a proton therapy, to allow re-optimisation during the course of a patient's treatment. The challenge of ensuring that plans are robust to range uncertainties in proton therapy remains, although these methods can provide practical solutions. PMID:23255545

  19. Regression techniques for Portfolio Optimisation using MOSEK

    OpenAIRE

    Schmelzer, Thomas; Hauser, Raphael; Andersen, Erling; Dahl, Joachim

    2013-01-01

    Regression is widely used by practioners across many disciplines. We reformulate the underlying optimisation problem as a second-order conic program providing the flexibility often needed in applications. Using examples from portfolio management and quantitative trading we solve regression problems with and without constraints. Several Python code fragments are given. The code and data are available online at http://www.github.com/tschm/MosekRegression.

  20. Computationally efficient optimisation algorithms for WECs arrays

    DEFF Research Database (Denmark)

    Ferri, Francesco

    2017-01-01

    In this paper two derivative-free global optimization algorithms are applied for the maximisation of the energy absorbed by wave energy converter (WEC) arrays. Wave energy is a large and mostly untapped source of energy that could have a key role in the future energy mix. The collection of this r...... a comparison between derivative-free global optimisation algorithms. In particular, evolutionary strategies (CMA-ES) and metamodel based optimisations algorithms are compared in terms of accuracy and computational time.......In this paper two derivative-free global optimization algorithms are applied for the maximisation of the energy absorbed by wave energy converter (WEC) arrays. Wave energy is a large and mostly untapped source of energy that could have a key role in the future energy mix. The collection...... output. Although started in the late seventies, the topic of WEC array optimisation has gathered a renovated interest mostly in the last decade, and a number of different approaches has been already used, from traditional algorithms to heuristic ones. The objective of this paper is to present...

  1. Designing Lead Optimisation of MMP-12 Inhibitors

    Directory of Open Access Journals (Sweden)

    Matteo Borrotti

    2014-01-01

    Full Text Available The design of new molecules with desired properties is in general a very difficult problem, involving heavy experimentation with high investment of resources and possible negative impact on the environment. The standard approach consists of iteration among formulation, synthesis, and testing cycles, which is a very long and laborious process. In this paper we address the so-called lead optimisation process by developing a new strategy to design experiments and modelling data, namely, the evolutionary model-based design for optimisation (EDO. This approach is developed on a very small set of experimental points, which change in relation to the response of the experimentation according to the principle of evolution and insights gained through statistical models. This new procedure is validated on a data set provided as test environment by Pickett et al. (2011, and the results are analysed and compared to the genetic algorithm optimisation (GAO as a benchmark. The very good performance of the EDO approach is shown in its capacity to uncover the optimum value using a very limited set of experimental points, avoiding unnecessary experimentation.

  2. Designing Lead Optimisation of MMP-12 Inhibitors

    Science.gov (United States)

    Borrotti, Matteo; De March, Davide; Slanzi, Debora; Poli, Irene

    2014-01-01

    The design of new molecules with desired properties is in general a very difficult problem, involving heavy experimentation with high investment of resources and possible negative impact on the environment. The standard approach consists of iteration among formulation, synthesis, and testing cycles, which is a very long and laborious process. In this paper we address the so-called lead optimisation process by developing a new strategy to design experiments and modelling data, namely, the evolutionary model-based design for optimisation (EDO). This approach is developed on a very small set of experimental points, which change in relation to the response of the experimentation according to the principle of evolution and insights gained through statistical models. This new procedure is validated on a data set provided as test environment by Pickett et al. (2011), and the results are analysed and compared to the genetic algorithm optimisation (GAO) as a benchmark. The very good performance of the EDO approach is shown in its capacity to uncover the optimum value using a very limited set of experimental points, avoiding unnecessary experimentation. PMID:24527058

  3. Natural Erosion of Sandstone as Shape Optimisation.

    Science.gov (United States)

    Ostanin, Igor; Safonov, Alexander; Oseledets, Ivan

    2017-12-11

    Natural arches, pillars and other exotic sandstone formations have always been attracting attention for their unusual shapes and amazing mechanical balance that leave a strong impression of intelligent design rather than the result of a stochastic process. It has been recently demonstrated that these shapes could have been the result of the negative feedback between stress and erosion that originates in fundamental laws of friction between the rock's constituent particles. Here we present a deeper analysis of this idea and bridge it with the approaches utilized in shape and topology optimisation. It appears that the processes of natural erosion, driven by stochastic surface forces and Mohr-Coulomb law of dry friction, can be viewed within the framework of local optimisation for minimum elastic strain energy. Our hypothesis is confirmed by numerical simulations of the erosion using the topological-shape optimisation model. Our work contributes to a better understanding of stochastic erosion and feasible landscape formations that could be found on Earth and beyond.

  4. Exploration of automatic optimisation for CUDA programming

    KAUST Repository

    Al-Mouhamed, Mayez

    2014-09-16

    © 2014 Taylor & Francis. Writing optimised compute unified device architecture (CUDA) program for graphic processing units (GPUs) is complex even for experts. We present a design methodology for a restructuring tool that converts C-loops into optimised CUDA kernels based on a three-step algorithm which are loop tiling, coalesced memory access and resource optimisation. A method for finding possible loop tiling solutions with coalesced memory access is developed and a simplified algorithm for restructuring C-loops into an efficient CUDA kernel is presented. In the evaluation, we implement matrix multiply (MM), matrix transpose (M-transpose), matrix scaling (M-scaling) and matrix vector multiply (MV) using the proposed algorithm. We present the analysis of the execution time and GPU throughput for the above applications, which favourably compare to other proposals. Evaluation is carried out while scaling the problem size and running under a variety of kernel configurations. The obtained speedup is about 28-35% for M-transpose compared to NVIDIA Software Development Kit, 33% speedup for MV compared to general purpose computation on graphics processing unit compiler, and more than 80% speedup for MM and M-scaling compared to CUDA-lite.

  5. Procedure for Application-Oriented Optimisation of Marine Propellers

    Directory of Open Access Journals (Sweden)

    Florian Vesting

    2016-11-01

    Full Text Available The use of automated optimisation in engineering applications is emerging. In particular, nature inspired algorithms are frequently used because of their variability and robust application in constraints and multi-objective optimisation problems. The purpose of this paper is the comparison of four different algorithms and several optimisation strategies on a set of seven test propellers in realistic industrial design setting. The propellers are picked from real commercial projects and the manual final designs were delivered to customers. The different approaches are evaluated and final results of the automated optimisation toolbox are compared with designs generated in a manual design process. We identify a two-stage optimisation for marine propellers, where the geometry is first modified by parametrised geometry distribution curves to gather knowledge of the test case. Here we vary the optimisation strategy in terms of applied algorithms, constraints and objectives. A second supporting optimisation aims to improve the design by locally changing the geometry, based on the results of the first optimisation. The optimisation algorithms and strategies yield propeller designs that are comparable to the manually designed propeller blade geometries, thus being suitable as robust and advanced design support tools. The supporting optimisation, with local modification of the blade geometry and the proposed cavity shape constraints, features particular good performance in modifying cavitation on the blade and is, with the AS NSGA-II (adaptive surrogate-assisted NSGA-II, superior in lead time.

  6. Influence of maleic acid copolymers on calcium orthophosphates crystallization at low temperature

    Science.gov (United States)

    Pelin, Irina M.; Popescu, Irina; Suflet, Dana M.; Aflori, Magdalena; Bulacovschi, Victor

    2013-08-01

    The goal of this study was to investigate the maleic acid copolymers role on calcium orthophosphates crystallization at low temperature. In this respect, two maleic acid copolymers with different structures [poly(sodium maleate-co-vinyl acetate) and poly(sodium maleate-co-methyl methacrylate)] were used. The syntheses of the calcium orthophosphates in the absence and in the presence of the copolymers were performed through the wet chemical method using calcium nitrate, ammonium dihydrogen phosphate and ammonium hydroxide as reactants. The syntheses were monitored in situ by potentiometric and conductometric measurements. To ensure the transformation of less thermodynamically stable calcium orthophosphates into more stable forms, the samples were aged 30 days in mother solutions, at room temperature. The presence of the copolymers in the final products was evidenced by FTIR spectroscopy and thermogravimetric analysis. Scanning and transmission electron microscopy and laser light scattering measurements gave information about the composites morphology and the size of the formed structures. X-ray diffraction evidenced that, as a function of comonomer structure and of copolymer concentration, the products could contain hydroxyapatite with low crystallinity, calcium-deficient or carbonated hydroxyapatite. At high concentration of poly(sodium maleate-co-methyl methacrylate) the transformation of brushite into apatitic structures was inhibited.

  7. Bioactivity and mineralization of hydroxyapatite with bioglass as sintering aid and bioceramics with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} and Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} in a silicate matrix

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States); Mohandas, Arunesh; Dohi, Motokazi; Fuentes, Alonso; Nguyen, Kytai [Bioengineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States); Aswath, Pranesh, E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2010-01-30

    Hydroxyapatite and Bioglass-45S5 were sintered together creating new ceramic compositions that yielded increased apatite deposition and osteoblast differentiation and proliferation in vitro compared to hydroxyapatite. The sintered products characterized by X-ray diffraction, revealed hydroxyapatite as the main phase when small quantities (1, 2.5 and 5 wt.%) of bioglass was added. Bioglass behaved as a sintering aid with {beta}-TCP (Ca{sub 3}(PO{sub 4}){sub 2}) being the minor phase. The amount of {beta}-TCP increased with the amount of bioglass added. In compositions with larger additions of bioglass (10 and 25 wt.%), new phases with compositions of calcium phosphate silicate (Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4}) and sodium calcium phosphate (Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5}) were formed respectively within amorphous silicate matrices. In vitro cell culture studies of the ceramic compositions were examined using bone marrow stromal cell (BMSC). Cell proliferation and differentiation of bone marrow stromal cells into osteoblasts were determined by Pico Green DNA assays and alkaline phosphatase (ALP) activity, respectively. All hydroxyapatite-bioglass co-sintered ceramics exhibited larger cell proliferation compared to pure hydroxyapatite samples. After 6 days in cell culture, the ceramic with Ca{sub 5}(PO{sub 4}){sub 3}SiO{sub 4} in a silicate matrix formed by reacting hydroxyapatite with 10 wt.% bioglass exhibited the maximum proliferation of the BMSC's. The ALP activity was found to be largest in the ceramic with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} embedded in a silicate matrix synthesized by reacting hydroxyapatite with 25 wt.% bioglass.

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

    DEFF Research Database (Denmark)

    Boskey, Adele L.; Christensen, Brian Søndergaard; Taleb, Hayat

    2012-01-01

    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...

  9. Hydroxyapatite and fluor-hydroxyapatite layered film on titanium processed by a sol-gel route for hard-tissue implants.

    Science.gov (United States)

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

    2004-10-15

    A double-layered coating, consisting of a hydroxyapatite (HA) outer film and a fluor-hydroxyapatite (FHA) inner film, was produced on a Ti substrate by a sol-gel route to improve the biocompatibility and functionality of the system. Dissolution behavior of and in vitro cellular responses to the layered film were investigated. Calcium nitrate and triethyl phosphite were used for calcium and phosphate precursors, respectively, and ammonium fluoride was added as a fluorine-ion source for FHA. The FHA layer was deposited on Ti by spin coating and subsequent heat treatment at 550 degrees C for 30 min in air, and then the HA layer was laid down over the FHA-coated Ti under the same conditions. After heat treatment, characteristic apatite structures and phases were developed on both FHA and HA films. The cross-section view of the HA/FHA film clearly showed a double-layered structure on Ti with each layer approximately 0.6-0.8-microm thickness. The coating layer was highly uniform and dense, and adhered to Ti substrate strongly with an adhesion strength of about 40 MPa. The in vitro solubility of the HA/FHA layered film in a physiological solution was between that of HA and FHA pure film, and the dissolution profile was quite biphasic, that is, an initial rapid period and a slowdown with increasing time, reflecting the gradient solubility of the fast HA outer structure/slow FHA inner structure. The human osteoblast-like HOS TE85 cells cultured on the HA/FHA layered film attached, spread, and grew favorably. The proliferation rate of the cells on the layered film was significantly higher (considered at p < 0.05 for n = 6) than that on Ti substrate and was similar to that on pure HA film. The alkaline phosphatase (ALP) activity and osteocalcin (OC) produced by the cells on the layered film were significantly higher (considered at p < 0.05 for n = 6) than those on Ti substrate. Moreover, the ALP and OC levels of cells on the layered film showed the trends of HA outer

  10. Railway vehicle performance optimisation using virtual homologation

    Science.gov (United States)

    Magalhães, H.; Madeira, J. F. A.; Ambrósio, J.; Pombo, J.

    2016-09-01

    Unlike regular automotive vehicles, which are designed to travel in different types of roads, railway vehicles travel mostly in the same route during their life cycle. To accept the operation of a railway vehicle in a particular network, a homologation process is required according to local standard regulations. In Europe, the standards EN 14363 and UIC 518, which are used for railway vehicle acceptance, require on-track tests and/or numerical simulations. An important advantage of using virtual homologation is the reduction of the high costs associated with on-track tests by studying the railway vehicle performance in different operation conditions. This work proposes a methodology for the improvement of railway vehicle design with the objective of its operation in selected railway tracks by using optimisation. The analyses required for the vehicle improvement are performed under control of the optimisation method global and local optimisation using direct search. To quantify the performance of the vehicle, a new objective function is proposed, which includes: a Dynamic Performance Index, defined as a weighted sum of the indices obtained from the virtual homologation process; the non-compensated acceleration, which is related to the operational velocity; and a penalty associated with cases where the vehicle presents an unacceptable dynamic behaviour according to the standards. Thus, the optimisation process intends not only to improve the quality of the vehicle in terms of running safety and ride quality, but also to increase the vehicle availability via the reduction of the time for a journey while ensuring its operational acceptance under the standards. The design variables include the suspension characteristics and the operational velocity of the vehicle, which are allowed to vary in an acceptable range of variation. The results of the optimisation lead to a global minimum of the objective function in which the suspensions characteristics of the vehicle are

  11. Sintering mechanism of the CaF2 on hydroxyapatite by a 10.6-l microm CO2 laser.

    Science.gov (United States)

    Wu, Cheng-Chei; Roan, Rong-Tai; Chen, Jeng-Huey

    2002-01-01

    Laser has been reported as a heat source for melting and re-crystallization. Occurring at about 1100 degrees C, the melting of surface dental enamel along with re-crystallization might have an assistant role in the therapy of hypersensitive tooth, apical sealing of endodontic surgery in dentistry, preventive dentistry for pit and fissure sealing, and fluoridation. For laser to be accepted in clinical applications, it is desired that, studies must show the incorporation of CaF(2) into hydroxyapatite could reduce the sintering temperature for the sake of safety. In this study, the Sharplan 20XJ CO(2) laser with 10.6- microm wavelength was set under the following parameters: power, 5 W; repetitive mode, 0.1 second; beam, focused. Fluorite was added to hydroxyapatite as a synthetic compound to lower the sintering temperature. Human dental enamel without caries was used for in vitro sintering test. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transforming infrared spectroscopy (FTIR), and differential thermal analysis/thermogravimetric analysis (DAT/TGA) were used for the investigation of sintering mechanism of CaF(2). Fusion between hexagonal shape crystals and cubic shape crystals (CaF(2)) were observed under SEM study. Hexagonal shape crystals indicated the formation of fluorapatite under XRD analysis. Under FTIR study, we examined reductions of water (3445 cm(-1)) and hydroxyl bands (3567 and 627 cm(-1)) in irradiated compounds. From the DTA pattern of synthetic compound, it showed the endothermic reaction reaching its peak point around 1180 +/- 20 degrees C. It was attributed to the phase transformation and/or initial melting. In this study, we proposed the interrelationship of the eutectics between initiator (CaF(2)) and the reaction product (calcium hydroxide) that reduced the sintering temperature. It appeared that the co-eutectics interacted to reduce the sintering temperature of hydroxyapatite below 800 degrees C and that the key

  12. Short-fibre reinforcement of calcium phosphate bone cement.

    Science.gov (United States)

    Buchanan, F; Gallagher, L; Jack, V; Dunne, N

    2007-02-01

    Calcium phosphate cement (CPC) sets to form hydroxyapatite, a major component of mineral bone, and is gaining increasing interest in bone repair applications. However, concerns regarding its brittleness and tendency to fragment have limited its widespread use. In the present study, short-fibre reinforcement of an apatitic calcium phosphate has been investigated to improve the fracture behaviour. The fibres used were polypropylene (PP) fibres, 50 microm in diameter and reduced in length by cryogenic grinding. The compressive strength and fracture behaviour were examined. Fibre addition of up to 10 wt % had a significant effect on composite properties, with the energy absorbed during failure being significantly increased, although this tended to be accompanied with a slight drop in compressive strength. The fibre reinforcement mechanisms appeared to be crack bridging and fibre pull-out. The setting time of the CPC with fibre reinforcement was also investigated and was found to increase with fibre volume fraction.

  13. Effects of HA released calcium ion on osteoblast differentiation.

    Science.gov (United States)

    Jung, Gil-Yong; Park, Yoon-Jeong; Han, Jung-Suk

    2010-05-01

    Hydroxyapatite (HA) is a widely used calcium phosphate implant substitute and has dissolution property. Although HA has been shown a beneficial effect on osteoblast differentiation, the exact mechanism is still unclear. In the present study, we proposed that Ca(2+) released from HA activated the expression bone associated proteins, OPN and BSP, mediated by L-type calcium channel and calcium/calmodulin-dependent protein kinase (CaMK) 2 which resulted into improved osteoblast differentiation. Results showed that HA elevated ALP expression as well as OPN and BSP expression in MC3T3-E1 cells. The result from western blot of CaMK2alpha indicated that HA released Ca(2+) activated CaMK2 through L-type calcium channel. Furthermore, upregulation of OPN and BSP mRNA expression was significantly inhibited when blocking both the L-type calcium channel and CaMK2. These findings suggested that HA accelerated the osteoblast differentiation by releasing Ca(2+).

  14. [Cytotoxicity of the strontium-substituted hydroxyapatite evaluated by MTT colorimetry].

    Science.gov (United States)

    Fu, Y; Chen, D; Zhang, J

    2001-09-01

    This study was conducted to evaluate the cytotoxicity of strontium-substituted hydroxyapatite by methyl thiazolyl tetrazolium (MTT) colorimetry. We used the MTT method to assay the cytotoxicity of the strontium-substituted hydroxyapatite containing different strontium concentrations (1%, 5%, 10%, 100% Sr2+) and the pure hydroxyapatite. The results showed that the cytotoxicity scores of the different materials were grade 0 or grade 1. These led us to the conclusion that strontium-substituted hydroxyapatite has good biocompatibility.

  15. Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects

    Energy Technology Data Exchange (ETDEWEB)

    Han, I-H [Institute of Physics and Applied Physics, and Atomic-Scale Surface Science Research Center, Yonsei University, Seou1 120-749 (Korea, Republic of); Lee, I-S [Institute of Physics and Applied Physics, and Atomic-Scale Surface Science Research Center, Yonsei University, Seou1 120-749 (Korea, Republic of); Song, J-H [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lee, M-H [Department of Medical Engineering, Yonsei University, Seoul 120-752 (Korea, Republic of); Park, J-C [Department of Medical Engineering, Yonsei University, Seoul 120-752 (Korea, Republic of); Lee, G-H [Korea Institute of Machinery and Materials, Chang-Won 641-010 (Korea, Republic of); Sun, X-D [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Chung, S-M [Implantium Research Center, Seoul 135-879 (Korea, Republic of)

    2007-09-15

    A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO{sub 3} concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

  16. Study of synthesis of nano-hydroxyapatite using a silk fibroin template

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jing; Yu Feng; Qu Lijie; Meng Xiangcai [Provincial Key Laboratory of Biomaterials, Jiamusi University, Jiamusi 154007 (China); Wen, G [School of Materials Science and Engineering, Harbin Institute of Technology, Heilongjiang Province 150001 (China)

    2010-08-01

    Nano-hydroxyapatite (HA) was directly synthesized on a silk fibroin (SF) template using the property of SF being soluable in a concentrated CaCl{sub 2} solution as a HA source of calcium at pH 7.4 and room temperature. The microstructure and bonding state were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TG) and transmission electron microscopy (TEM). The results indicated that the HA crystals were poorly crystallized with a rod-like shape of 20-60 nm length and 10-20 nm diameter. Strong molecular interactions and chemical bonds might be present between SF and HA. There were other nucleation sites such as carbonyl (-C-O) and amine (-N-H-) groups on SF molecules besides the carboxyl (-COOH) and hydroxyl (-OH) groups previously reported. During the formation of HA, the coordination action between specific functional groups on SF and calcium ions (Ca{sup 2+}) played an important role. The crystallinity of HA was improved and had an orientation growth along (0 0 2) at the presence of SF, resulting in a structure similar to natural bone. It was concluded that SF could regulate the structure and morphology of HA effectively. (communication)

  17. Three-Dimensional Printing of Nano Hydroxyapatite/Poly(ester urea) Composite Scaffolds with Enhanced Bioactivity.

    Science.gov (United States)

    Yu, Jiayi; Xu, Yanyi; Li, Shan; Seifert, Gabrielle V; Becker, Matthew L

    2017-10-25

    Polymer-bioceramic composites incorporate the desirable properties of each material while mitigating the limiting characteristics of each component. 1,6-Hexanediol l-phenylalanine-based poly(ester urea) (PEU) blended with hydroxyapatite (HA) nanocrystals were three-dimensional (3D) printed into porous scaffolds (75% porosity) via fused deposition modeling and seeded with MC3T3-E1 preosteoblast cells in vitro to examine their bioactivity. The resulting 3D printed scaffolds exhibited a compressive modulus of ∼50 MPa after a 1-week incubation in PBS at 37 °C, cell viability >95%, and a composition-dependent enhancement of radio-contrast. The influence of HA on MC3T3-E1 proliferation and differentiation was measured using quantitative real-time polymerase chain reaction, immunohistochemistry and biochemical assays. After 4 weeks, alkaline phosphatase activity increased significantly for the 30% HA composite with values reaching 2.5-fold greater than the control. Bone sialoprotein showed approximately 880-fold higher expression and 15-fold higher expression of osteocalcin on the 30% HA composite compared to those of the control. Calcium quantification results demonstrated a 185-fold increase of calcium concentration in mineralized extracellular matrix deposition after 4 weeks of cell culture in samples with higher HA content. 3D printed HA-containing PEU composites promote bone regeneration and have the potential to be used in orthopedic applications.

  18. Preparation of micro-porous bioceramic containing silicon-substituted hydroxyapatite and beta-tricalcium phosphate.

    Science.gov (United States)

    Fuh, Lih-Jyh; Huang, Ya-Jing; Chen, Wen-Cheng; Lin, Dan-Jae

    2017-06-01

    Dimensional instability caused by sintering shrinkage is an inevitable drawback for conventional processing of hydroxyapatite (HA). A new preparation method for biphasic calcium phosphates was developed to increase micro pores and biodegradation without significant dimensional change. Powder pressed HA discs, under 100MPa, were immersed in a colloidal mixture of tetraethoxysilane (TEOS) and ammonium hydroxide for 10min, followed by drying, and then were sintered at 900°C, 1050°C, and 1200°C, respectively. Comparing with pure HA discs, the newly prepared product sintered up to 1200°C contained silicon substituted HA, beta-tricalcium phosphate, and calcium silicate with better micro-porosity, high specific surface area, less sintering shrinkage and the strength maintained. The cytocompatibility test demonstrated a better viability for D1 mice stem cells cultured on TEOS treated HA for 14days compared to the pure HA. This simple TEOS sol-gel pretreatment has the potential to be applied to any existing manufacturing process of HA scaffold for better control of sintering shrinkage, create micropores, and increase biodegradation. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Preparation of magnetic hydroxyapatite clusters and their application in the enrichment of phosphopeptides.

    Science.gov (United States)

    Yu, Qiao; Li, Xiao-Shui; Yuan, Bi-Feng; Feng, Yu-Qi

    2014-03-01

    A novel strategy for the effective enrichment of phosphopeptides based on magnetic hydro-xyapatite (HAp) clusters was developed in the current study. The structure of HAp ensures its probable separation capability, including cation exchange with P-sites (negatively charged pairs of crystal phosphates), calcium coordination, anion exchange with C-sites (positively charged pairs of crystal calcium ions). The prepared magnetic HAp clusters showed good performance on the efficient enrichment of phosphopeptides from the digestion mixture of β-casein and BSA. Compared to commercial HAp particles, the magnetic HAp clusters exhibited better selectivity toward phosphopeptides. In addition, the use of magnetic material greatly simplified the enrichment procedure, which avoided the tedious centrifugation steps in a typical phosphopeptides enrichment protocol. Finally, the material was successfully applied in the enrichment of phosphopeptides from human serum. Taken together, the efficient enrichment of the phosphopeptides by the easily prepared magnetic HAp clusters demonstrated a rapid and convenient strategy for the purification of phosphopeptides from complex samples, which may facilitate protein phosphorylation studies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Highly controlled coating of strontium-doped hydroxyapatite on electrospun poly(ɛ-caprolactone) fibers.

    Science.gov (United States)

    Weng, Lin; Teusink, Matthew J; Shuler, Franklin D; Parecki, Vivi; Xie, Jingwei

    2017-05-01

    Electrospun fibers show great potential as scaffolds for bone tissue engineering due to their architectural biomimicry to the extracellular matrix (ECM). Cation substitution of strontium for calcium in hydroxyapatite (HAp) positively influences the mechanism of bone remodeling including enhancing bone regeneration and reducing bone resorption. The objective of this study was to attach strontium-doped HAp (SrHAp) to electrospun poly(ɛ-caprolactone) (PCL) fibers for creation of novel composite scaffolds that can not only mimic the architecture and composition of ECM but also affect bone remodeling favorably. We demonstrated for the first time the highly controlled SrHAp coatings on electrospun PCL fibers. We showed the reproducible manufacturing of composite fiber scaffolds with controllable thickness, composition, and morphology of SrHAp coatings. We further showed that the released strontium and calcium cations from coatings could reach effective concentrations within 1 day and endure more than 28 days. Additionally, the Young's modulus of the SrHAp-coated PCL fibers was up to around six times higher than that of raw fibers dependent on the coating thickness and composition. Together, this novel class of composite fiber scaffolds may hold great promise for bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 753-763, 2017. © 2016 Wiley Periodicals, Inc.

  1. Lanthanum-silicon-substituted hydroxyapatite: Mechanochemical synthesis and prospects for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Chaikina, M. V., E-mail: chaikinam@solid.nsc.ru; Bulina, N. V., E-mail: bulina@solid.nsc.ru; Prosanov, I. Yu., E-mail: prosanov@mail.ru [Institute of Solid State Chemistry and Mechanochemistry SB RAS, Kutateladze Street 18, Novosibirsk, 630128 (Russian Federation); Komarova, E. G., E-mail: katerina@ispms.tsc.ru; Sharkeev, Yu. P., E-mail: sharkeev@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Academicheskii Pr. 2/4, Tomsk, 634055 (Russian Federation)

    2016-08-02

    The paper presents the results of mechanochemical synthesis of hydroxyapatite (HAP) with simultaneous substitutions of lanthanum (La{sup 3+}) for calcium ions and silicate ((SiO{sub 4}){sup 4−}-group) for the phosphate group with the substituent concentrations in the range 0.2–2.0 mol per HAP mol. The use of Si-substituted HAP as a coating material promotes accelerated osteosynthesis and osteointegration of implants into the bone tissue. The replacement of calcium ions by La{sup 3+} in the HAP structure plays an antimicrobial role preventing inflammatory processes. Annealing-induced variations in the lattice parameters of synthesized samples indicate the substituent incorporation into the HAP structure. It is known that complex compounds with lanthanides are used for cancer chemotherapy. In particular, La plays a key role in the course of treatment of injured defects of bone tissue. In addition, La-substituted HAP can be used for filling bone defects and coating implants in postoperational areas affected by bone cancer.

  2. Novel Hydroxyapatite Coatings for the Conservation of Marble and Limestone

    Science.gov (United States)

    Naidu, Sonia

    Marble and limestone are calcite-based materials used in the construction of various structures, many of which have significant artistic and architectural value. Unfortunately, due to calcite's high dissolution rate, these stones are susceptible to chemically-induced weathering in nature. Limestone, due to its inherent porosity, also faces other environmental weathering processes that cause weakening from disintegration at grain boundaries. The treatments presently available are all deficient in one way or another. The aim of this work is to examine the feasibility of using hydroxyapatite (HAP) as a novel protective coating for marble and limestone, with two goals: i) to reduce acid corrosion of marble and ii) to consolidate physically weathered limestone. The motivation for using HAP is its low dissolution rate and structural compatibility with calcite. Mild, wet chemical synthesis routes, in which inorganic phosphate-based solutions were reacted with marble and limestone, alone and with other precursors, were used to produce HAP films. Film nucleation, growth and phase evolution were studied on marble to understand film formation and determine the optimal synthesis route. An acid resistance test was developed to investigate the attack mechanism on marble and quantify the efficacy of HAP-based coatings. Film nucleation and growth were dependent on substrate surface roughness and increased with calcium and carbonate salt additions during synthesis. Acid attack on marble occurred via simultaneous dissolution at grain boundaries, twin boundaries and grain surfaces. HAP provided intermediate protection against acid attack, when compared to two conventional treatments. Its ability to protect the stone from acid was not as significant as predicted from dissolution kinetics and this was attributed to incomplete coverage and residual porosity within the film, arising from its flake-like crystal growth habit, which enabled acid to access the underlying substrate. The

  3. Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.

    Science.gov (United States)

    Horiuchi, Shinya; Hiasa, Masahiro; Yasue, Akihiro; Sekine, Kazumitsu; Hamada, Kenichi; Asaoka, Kenzo; Tanaka, Eiji

    2014-01-01

    Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials. © 2013 Elsevier Ltd. All rights reserved.

  4. Optimisation of thin shell parts by using particle swarm optimisation (PSO) method

    Science.gov (United States)

    Hidayah, M. H. N.; Shayfull, Z.; Nasir, S. M.; Sazli, S. M.; Fathullah, M.

    2017-09-01

    This paper proposes an optimization model of process parameters in Plastic Injection Moulding (PIM) in which the quality characteristics for the plastic injection product that been study are warpage. In this study, plastic dispenser of dental floss (thin shell part) has been analysed with thermoplastic material of Polypropylene (PP) used as the moulded material. Design of Experiment (DOE), Response surface methodology (RSM) and Particle Swarm Optimisation (PSO) method were used to analyse the optimal process parameters setting. From optimal processing parameter, the value of warpage inx, y and z-axis have been optimised by 22.1%, 27.34% and 23.81%, respectively.

  5. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  6. Virtual topological optimisation of scaffolds for rapid prototyping.

    Science.gov (United States)

    Almeida, Henrique de Amorim; Bártolo, Paulo Jorge da Silva

    2010-09-01

    Advanced additive techniques are now being developed to fabricate scaffolds with controlled architecture for tissue engineering. These techniques combine computer-aided design (CAD) with computer-aided manufacturing (CAM) tools to produce three-dimensional structures layer by layer in a multitude of materials. Actual prediction of the effective mechanical properties of scaffolds produced by additive technologies, is very important for tissue engineering applications. A novel computer based technique for scaffold design is topological optimisation. Topological optimisation is a form of "shape" optimisation, usually referred to as "layout" optimisation. The goal of topological optimisation is to find the best use of material for a body that is subjected to either a single load or a multiple load distribution. This paper proposes a topological optimisation scheme in order to obtain the ideal topological architectures of scaffolds, maximising its mechanical behaviour. 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

  7. Synthesis and characterization of biocompatible hydroxyapatite ...

    Indian Academy of Sciences (India)

    Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical composition (CaO)0.75(La2O3)0.20(Fe2O3)6 was prepared using ...

  8. Mechatronic System Design Based On An Optimisation Approach

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Pedersen, Henrik Clemmensen; Hansen, Michael Rygaard

    The envisaged objective of this paper project is to extend the current state of the art regarding the design of complex mechatronic systems utilizing an optimisation approach. We propose to investigate a novel framework for mechatronic system design. The novelty and originality being the use...... of optimisation techniques. The methods used to optimise/design within the classical disciplines will be identified and extended to mechatronic system design....

  9. Morphological and Cell Growth Assessment in Near Dense Hydroxyapatite Scaffold

    Directory of Open Access Journals (Sweden)

    Florencia Edith Wiria

    2013-01-01

    Full Text Available This paper reports the preliminary results on the morphology of low porosity hydroxyapatite scaffold and its compatibility as a substrate for osteoblast cells. Although having low porosity, the hydroxyapatite scaffold was found to be capable of sustaining cell growth and thus assisting bone ingrowth. Due to the low porosity nature, the scaffold provides higher strength and therefore more suitable for applications with load-bearing requirements such as spinal spacer. The hydroxyapatite scaffolds are prepared via powder processing techniques, using a combination of wet mixing, powder compaction, and sintering processes. The scaffold porosity is estimated via image analysis and micro-CT, which detect porosity level of approximately 16% and pore size of 13 μm. Cell culture investigation demonstrates that the hydroxyapatite substrate is able to provide favourable cell attachment and collagen matrix production, as compared to the commonly used cell culture control substrates. These results indicate that despite the low porosity in the hydroxyapatite scaffolds, they do not hinder being a preferred substrate to provide conducive environment osteoblast cell growth.

  10. Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application.

    Science.gov (United States)

    Kulanthaivel, Senthilguru; Roy, Bibhas; Agarwal, Tarun; Giri, Supratim; Pramanik, Krishna; Pal, Kunal; Ray, Sirsendu S; Maiti, Tapas K; Banerjee, Indranil

    2016-01-01

    The present study delineates the synthesis and characterization of cobalt doped proangiogenic-osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co(2+)) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP-OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic-osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Bisphosphonates enhance bacterial adhesion and biofilm formation on bone hydroxyapatite.

    Science.gov (United States)

    Kos, Marcin; Junka, Adam; Smutnicka, Danuta; Szymczyk, Patrycja; Gluza, Karolina; Bartoszewicz, Marzenna

    2015-07-01

    Because of the suspicion that bisphosphonates enhance bacterial colonization, this study evaluated adhesion and biofilm formation by Streptococcus mutans 25175, Staphylococcus aureus 6538, and Pseudomonas aeruginosa 14454 reference strains on hydroxyapatite coated with clodronate, pamidronate, or zoledronate. Bacterial strains were cultured on bisphosphonate-coated and noncoated hydroxyapatite discs. After incubation, nonadhered bacteria were removed by centrifugation. Biofilm formation was confirmed by scanning electron microscopy. Bacterial colonization was estimated using quantitative cultures compared by means with Kruskal-Wallis and post-hoc Student-Newman-Keuls tests. Modeling of the interactions between bisphosphonates and hydroxyapatite was performed using the Density Functional Theory method. Bacterial colonization of the hydroxyapatite discs was significantly higher for all tested strains in the presence of bisphosphonates vs. Adherence in the presence of pamidronate was higher than with other bisphosphonates. Density Functional Theory analysis showed that the protonated amine group of pamidronate, which are not present in clodronate or zoledronate, forms two additional hydrogen bonds with hydroxyapatite. Moreover, the reactive cationic amino group of pamidronate may attract bacteria by direct electrostatic interaction. Increased bacterial adhesion and biofilm formation can promote osteomyelitis, cause failure of dental implants or bisphosphonate-coated joint prostheses, and complicate bone surgery in patients on bisphosphonates. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  12. New Bismuth-Substituted Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    Science.gov (United States)

    Ciobanu, Gabriela; Bargan, Ana Maria; Luca, Constantin

    2015-11-01

    New bismuth-substituted hydroxyapatite [Ca10- x Bi x (PO4)6(OH)2 where x = 0-2.5] nanoparticles were synthesized by the co-precipitation method from aqueous solutions. The structural properties of the samples were analyzed by scanning electron microscopy coupled with x-ray analysis, x-ray powder diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller surface area analysis. The results confirm that bismuth ions have been incorporated into the hydroxyapatite lattice. The prepared nanocrystalline powders consisted of hydroxyapatite as single phase with hexagonal structure, crystal sizes smaller than 60 nm and (Bi + Ca)/P atomic ratio of around 1.67. The hydroxyapatite samples doped with Bi have mesoporous textures with pores size of around 2 nm and specific surface area in the range of 12-25 m2/g. The Bi-substituted hydroxyapatite powders are more effective against Gram-negative Escherichia coli bacteria than Gram-positive Staphylococcus aureus bacteria.

  13. Improving Vector Evaluated Particle Swarm Optimisation by incorporating nondominated solutions.

    Science.gov (United States)

    Lim, Kian Sheng; Ibrahim, Zuwairie; Buyamin, Salinda; Ahmad, Anita; Naim, Faradila; Ghazali, Kamarul Hawari; Mokhtar, Norrima

    2013-01-01

    The Vector Evaluated Particle Swarm Optimisation algorithm is widely used to solve multiobjective optimisation problems. This algorithm optimises one objective using a swarm of particles where their movements are guided by the best solution found by another swarm. However, the best solution of a swarm is only updated when a newly generated solution has better fitness than the best solution at the objective function optimised by that swarm, yielding poor solutions for the multiobjective optimisation problems. Thus, an improved Vector Evaluated Particle Swarm Optimisation algorithm is introduced by incorporating the nondominated solutions as the guidance for a swarm rather than using the best solution from another swarm. In this paper, the performance of improved Vector Evaluated Particle Swarm Optimisation algorithm is investigated using performance measures such as the number of nondominated solutions found, the generational distance, the spread, and the hypervolume. The results suggest that the improved Vector Evaluated Particle Swarm Optimisation algorithm has impressive performance compared with the conventional Vector Evaluated Particle Swarm Optimisation algorithm.

  14. Biodegradable magnesium-hydroxyapatite metal matrix composites.

    Science.gov (United States)

    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.

  15. Chemical characterization of some substituted hydroxyapatites

    Directory of Open Access Journals (Sweden)

    Ibrahim Doreya

    2011-11-01

    Full Text Available Abstract 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.

  16. Chemical characterization of some substituted hydroxyapatites.

    Science.gov (United States)

    Ibrahim, Doreya Mohamed; Mostafa, Amany A; Korowash, Sara Ibrahim

    2011-11-28

    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.

  17. [Induced synthesis of hydroxyapatite by Aspergillus niger].

    Science.gov (United States)

    He, Fei; Lian, Bin; Liu, Shirong; Gong, Guohong

    2011-03-01

    The research objective is to induce hydroxyapatite (HAP) synthesis by using fungus. We used the PDA (Potato Dextrose Agar Medium) liquid medium containing different concentrations of Na2HPO4 and CaCO3 to study the way Aspergillus niger synthesize HAP, to observe the induced mineral crystal structure and to analyze the induced mineral type with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The main results are as follows: (1) A. niger can induce HAP synthesis in PDA liquid medium with the proper concentration of Na2HPO4 and CaCO3. (2) The reaction of A. niger inducing HAP synthesis depends on the time of the response system. Longer time is more advantageous in producing HAP. The main reason for A. niger inducing HAP crystals formation are as follows: fungal metabolism produces the acidic substances to dissolve CaCO, and the growth mycelia absorbing Ca2+ lead to Ca2+ enriched on the surface, to promote the production of secondary mineral apatite and further transform into HAP in the mycelia spheres. A. niger can inducing HAP crystals formation in PDA liquid medium containing Na2HPO4 and CaCO3. Considering the importance of HAP in bio-medicine materials and its costly prices, our method for HAP bio-induction is of the temperate response condition, simple preparation craft, and lower cost, which has the potential application prospect.

  18. Electron paramagnetic resonance dosimetry using synthetic hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwon; Kim, Hwi Young; Ye, Sung Joon [Seoul National University, Seoul (Korea, Republic of); Hirata, Hiroshi [Hokkaido University, Sapporo (Japan); Park, Jong Min [Seoul National University Hospital, Seoul (Korea, Republic of)

    2014-11-15

    The victims exposed doses under 3.5-4.0 Gy have chance to survive if treated urgently. To determine the priority of treatment among a large number of victims, the triage – distinguishing patients who need an urgent treatment from who may not be urgent – is necessary based on radiation biodosimetry. A current gold standard for radiation biodosimetry is the chromosomal assay using human lymphocytes. But this method requires too much time and skilled labors to cover the mass victims in radiation emergencies. Electron paramagnetic resonance (EPR) has been known for its capability of quantifying radicals in matters. EPR dosimetry is based on the measurement of stable radiation-induced radicals in tooth enamel. Hydroxyapatite (HAP) (Ca10(PO4)6(OH)2) contained in tooth enamel is a major probe for radiation dose reconstruction. This HAP dosimetry study was performed using a novel EPR spectrometer in Hokkaido University, Japan. The EPR dose-response curve was made using HAP samples. The blind test using 250 cGy samples showed the feasibility of EPR dosimetry for the triage purpose.

  19. A novel biomagnetic nanoparticle based on hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H-C [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan (China); Wang, T-W [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan (China); Sun, J-S [Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan (China); Wang, W-H [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, F-H [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Taiwan (China)

    2007-04-25

    In the present study, magnetic HAP was synthesized at different ratios of Fe:Ca (X{sub Fe/Ca}) by the co-precipitation method. We have evaluated the present essential properties including the crystal structure and cell parameters by XRD, lattice arrangement by HR-TEM, composition analysis by ICP-MS, and functional groups by FTIR. The morphology and magnetization were investigated by SEM and AFM and SQUID, respectively. The in vitro biocompatibility was also investigated with a lactate dehydrogenase assay. The results showed that the crystal and molecular structure of the synthesized magnetic-HAP nanoparticle remained unaltered without collapse with the addition of iron ions. The lattice constants of m-HAP were similar to reference JCPDS card no. 9-432. The magnetization of m-HAP nanoparticles increased with increasing X{sub Fe/Ca} and possessed the superparamagnetic property with size distribution around 20 nm. The hydroxyapatite-based magnetic nanoparticles were also examined with good biocompatibility. With the appropriate physico-chemical and biological properties, the magnetic-HAP nanoparticles would have great potential to be applied in biomedical applications.

  20. A novel biomagnetic nanoparticle based on hydroxyapatite

    Science.gov (United States)

    Wu, Hsi-Chin; Wang, Tzu-Wei; Sun, Jui-Sheng; Wang, Wen-Hsi; Lin, Feng-Huei

    2007-04-01

    In the present study, magnetic HAP was synthesized at different ratios of Fe:Ca (XFe/Ca) by the co-precipitation method. We have evaluated the present essential properties including the crystal structure and cell parameters by XRD, lattice arrangement by HR-TEM, composition analysis by ICP-MS, and functional groups by FTIR. The morphology and magnetization were investigated by SEM and AFM and SQUID, respectively. The in vitro biocompatibility was also investigated with a lactate dehydrogenase assay. The results showed that the crystal and molecular structure of the synthesized magnetic-HAP nanoparticle remained unaltered without collapse with the addition of iron ions. The lattice constants of m-HAP were similar to reference JCPDS card no. 9-432. The magnetization of m-HAP nanoparticles increased with increasing XFe/Ca and possessed the superparamagnetic property with size distribution around 20 nm. The hydroxyapatite-based magnetic nanoparticles were also examined with good biocompatibility. With the appropriate physico-chemical and biological properties, the magnetic-HAP nanoparticles would have great potential to be applied in biomedical applications.

  1. Synthesis of hydroxyapatite nanotubes for biomedical applications.

    Science.gov (United States)

    Chandanshive, Balasaheb B; Rai, Priyanka; Rossi, Andre L; Ersen, Ovidiu; Khushalani, Deepa

    2013-07-01

    Single phase, stoichiometrically pure, hollow nanotubes of hydroxyapatite have been synthesized and single-particle analysis has been performed to successfully prove the sole formation of Ca10(PO4)6(OH)2 phase. The facile synthesis involves a sol-gel process under neutral conditions in the presence of a sacrifical anodic alumina template. The structures formed are hollow nanotubes that have been characterized by XRD, SEM, TEM, SAED, EELS, EDS and BET measurements. The diameter of the resulting tubes is in the range of 140-350 nm, length is on the order of a few microns and the wall thickness of the tubes was found to be ca. 30 nm. Moreover these tubes had a large BET surface area of 115 m(2)/g and were found to be biocompatible. They displayed inertness in the presence of NIH 3T3 mouse fibroblast cells as dictated by an MTT assay. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Porous hydroxyapatite for artificial bone applications

    Directory of Open Access Journals (Sweden)

    I. Sopyan et al

    2007-01-01

    Full Text Available Hydroxyapatite (HA has been used clinically for many years. It has good biocompatibility in bone contact as its chemical composition is similar to that of bone material. Porous HA ceramics have found enormous use in biomedical applications including bone tissue regeneration, cell proliferation, and drug delivery. In bone tissue engineering it has been applied as filling material for bone defects and augmentation, artificial bone graft material, and prosthesis revision surgery. Its high surface area leads to excellent osteoconductivity and resorbability providing fast bone ingrowth. Porous HA can be produced by a number of methods including conversion of natural bones, ceramic foaming technique, polymeric sponge method, gel casting of foams, starch consolidation, microwave processing, slip casting, and electrophoretic deposition technique. Some of these methods have been combined to fabricate porous HA with improved properties. These combination methods have yielded some promising results. This paper discusses briefly fundamental aspects of porous HA for artificial bone applications as well as various techniques used to prepare porous HA. Some of our recent results on development of porous HA will be presented as well.

  3. Graphene oxide/oxidized carbon nanofiber/mineralized hydroxyapatite based hybrid composite for biomedical applications

    Science.gov (United States)

    Murugan, N.; Sundaramurthy, Anandhakumar; Chen, Shen-Ming; Sundramoorthy, Ashok K.

    2017-12-01

    Hydroxyapatite (Ca10(PO4)6(OH)2, HAP), a multi-mineral substituted calcium phosphate is the main mineral component of tooth enamel and bone, has become an important biomaterial for biomedical applications. However, as-synthesized HAP has poor mechanical properties and inferior wear resistance, so it is not suitable to use in bone tissue engineering applications. We report the successful incorporation of oxidized carbon nanofibers (O-CNF) and graphene oxide (GO) into the mineralized hydroxyapatite (M-HAP) which showed excellent mechanical and biological properties. GO improved the high mechanical strength and corrosion protection of the substrate in simulated body fluid (SBF) solution and promoted the viability of osteoblasts MG63 cells. As-prepared M-HAP/O-CNF/GO composite showed materials characteristics that similar to natural bone (M-HAP) with high mechanical strength. The resultant M-HAP/O-CNF/GO composite was characterized out by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and Fourier-transform infrared spectroscopy (FT-IR), respectively. The mechanical strength of the material was determined by Vicker’s micro-hardness method and it was found that M-HAP/O-CNF/GO (468  ±  4 Hv) composite has superior mechanical properties than M-HAP (330  ±  3 Hv) and M-HAP/GO (425  ±  5 Hv) samples. In addition, antibacterial activity of the composite was studied against Staphylococcus aureus and Escherichia coli. Furthermore, the cell viability of the composite was observed in vitro against osteoblast cells. All these studies confirmed that the M-HAP/O-CNF/GO composite can be considered as potential candidate for dental and orthopedic applications.

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

    Science.gov (United States)

    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

  5. Surface phosphonation enhances hydroxyapatite coating adhesion on polyetheretherketone and its osseointegration potential.

    Science.gov (United States)

    Mahjoubi, Hesameddin; Buck, Emily; Manimunda, Praveena; Farivar, Reza; Chromik, Richard; Murshed, Monzur; Cerruti, Marta

    2017-01-01

    Polyetheretherketone (PEEK) has excellent mechanical properties, biocompatibility, chemical resistance and radiolucency, making it suitable for use as orthopedic implants. However, its surface is hydrophobic and bioinert, and surface modification is required to improve its bioactivity. In this work, we showed that grafting phosphonate groups via diazonium chemistry enhances the bioactivity of PEEK. Decreased contact angle indicated reduced hydrophobicity as a result of the treatment and X-ray photoelectron spectroscopy (XPS) confirmed the attachment of phosphonate groups to the surface. The surface treatment not only accelerated hydroxyapatite (HA) deposition after immersion in simulated body fluid but also significantly increased the adhesion strength of HA particles on PEEK. MC3T3-E1 cell viability, metabolic activity and deposition of calcium-containing minerals were also enhanced by the phosphonation. After three months of implantation in a critical size calvarial defect model, a fibrous capsule surrounded untreated PEEK while no fibrous capsule was observed around the treated PEEK. Instead, mineral deposition was observed in the region between the treated PEEK implant and underlying bone. This work introduces a simple method to improve the potential of PEEK-based orthopedic implants. We have introduced phosphonate groups on the surface of PEEK substrates using diazonium chemistry. Our results show that the treatment not only increased the adhesion strength of hydroxyapatite particles deposited on PEEK in vitro by approximately 40% compared to unmodified PEEK, but also improved the metabolic activity and mineralization of MC3T3-E1 cells. When implanted in cranial defects in rats, the phosphonate coating enhanced the osseointegration of PEEK by successfully preventing the formation of a fibrous capsule and favoring mineral deposition between the implant and the surrounding bone. This work introduces a simple method to improve the potential of PEEK

  6. Remineralization potential of fully demineralized dentin infiltrated with silica and hydroxyapatite nanoparticles.

    Science.gov (United States)

    Besinis, Alexandros; van Noort, Richard; Martin, Nicolas

    2014-03-01

    This study investigates the potential of a novel guided tissue regeneration strategy, using fully demineralized dentin infiltrated with silica and hydroxyapatite (HA) nanoparticles (NPs), to remineralize dentin collagen that is completely devoid of native hydroxyapatite. Dentin blocks were fully demineralized with 4N formic acid and subsequently infiltrated with silica and HA NPs. The remineralizing potential of infiltrated dentin was assessed following a twelve week exposure to an artificial saliva solution by means of TEM, EDS and micro-CT. Measurements were taken at baseline and repeated at regular intervals for the duration of the study to quantify the P and Ca levels, the mineral volume percentage and mineral separation of the infiltrated dentin specimens compared to sound dentin and non-infiltrated controls. Infiltration of demineralized dentin with nano-HA restored up to 55% of the P and Ca levels at baseline. A local increase in the concentration of calcium phosphate compounds over a period of twelve weeks resulted in a higher concentration in P and Ca levels within the infiltrated specimens when compared to the non-infiltrated controls. Remineralization of demineralized dentin with silica NPs by immersion in artificial saliva was the most effective strategy, restoring 20% of the P levels of sound dentin. Micro-CT data showed a 16% recovery of the mineral volume in dentin infiltrated with silica NPs and a significant decrease in the mineral separation to levels comparable to sound dentin. Demineralized dentin infiltrated with silica NPs appears to encourage heterogeneous mineralization of the dentin collagen matrix following exposure to an artificial saliva solution. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Adsorption of tranexamic acid on hydroxyapatite: Toward the development of biomaterials with local hemostatic activity

    Energy Technology Data Exchange (ETDEWEB)

    Sarda, Stéphanie, E-mail: stephanie.sarda@iut-tlse3.fr [CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, Université Toulouse 3 Paul Sabatier, Toulouse (France); Errassifi, Farid [CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, Université Toulouse 3 Paul Sabatier, Toulouse (France); Marsan, Olivier [CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, ENSIACET, Toulouse (France); Geffre, Anne; Trumel, Catherine [Université de Toulouse, INP, ENVT, UMS006, Laboratoire Central de Biologie Médicale, Toulouse (France); INSERM-UPS, UMS 006, Laboratoire Central de Biologie Médicale, Toulouse (France); Drouet, Christophe [CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, ENSIACET, Toulouse (France)

    2016-09-01

    This work proposes to combine tranexamic acid (TAX), a clinically used antifibrinolytic agent, and hydroxyapatite (HA), widely used in bone replacement, to produce a novel bioactive apatitic biomaterial with intrinsic hemostatic properties. The aim of this study was to investigate adsorptive behavior of the TAX molecule onto HA and to point out its release in near physiological conditions. No other phase was observed by X-ray diffraction or transmission electron microscopy, and no apparent change in crystal size was detected. The presence of TAX on the powders was lightly detected on Raman spectra after adsorption. The adsorption data could be fitted with a Langmuir–Freundlich equation, suggesting a strong interaction between adsorbed molecules and the formation of multilayers. The concentration of calcium and phosphate ions in solution remained low and stable during the adsorption process, thus ion exchange during the adsorption process could be ruled out. The release of TAX was fast during the first hours and was governed by a complex process that likely involved both diffusion and dissolution of HA. Preliminary aPTT (activated partial thromboplastin time) hemostasis tests offered promising results for the development of osteoconductive apatitic biomaterials with intrinsic hemostatic properties, whether for dental or orthopedic applications. - Highlights: • Interaction of tranexamic acid (TAX)/hydroxyapatite was studied. • The adsorption data could be fitted with a Langmuir–Freundlich equation. • The release of TAX, fast during the first hours, was governed by a complex process. • Preliminary aPTT hemostasis tests show promising results. • The aim is to develop biomaterials with local hemostatic activity.

  8. [Preparation and characteristics of non-woven silk fibroin/nano-hydroxyapatite scaffolds].

    Science.gov (United States)

    Zhao, Yong; Li, Gang; Chen, Jing; Chen, Zhi-Qing

    2008-04-01

    The aim of the present study was to design and fabricate a three dimensional (3D) porous structure of silk fibroin/apatite used as a potential scaffold in bone tissue engineering. With the combining use of non-woven silk fibroin net and biomimetic method, porous non-woven silk fibroin/nano-hydroxyapatite net (NSF/nHAP) was prepared and characterized with X-ray diffraction (XRD), scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR). The porosity and swelling ratio of the 3D scaffold were also measured. Besides, the osteoblasts from the cranium of new born SD rat were cultured on the pre-fabricated scaffold to evaluate the biological reaction of the scaffold. The nano-sized hydroxyapatite crystals were needle-like with the length of 100-300 nm and the diameter of 20-60 nm. The scaffold fabricated in the present study exhibited the porous microstructure with open porosity around 70%-78%. Its average pore size was about (163.4 +/- 42.6) microm. The swelling ratio and water uptaking were 4.56% and 81.93%, respectively, which revealed that the 3D porous scaffold had an excellent hydrophilicity. The rod-shaped apatite crystals could rapidly form on the surface of fibroin fibers throughout the network by immersing the net into calcium and phosphate solutions alternatively. A 3D porous NSF/nHAP scaffold can be fabricated by biomimetic mineralization and none-woven silk fibroin method. The novel NSF/nHAP scaffold has an excellent cytocompatibility for the growth of osteoblasts. Porous NSF/nHAP scaffold may be a hopeful biomaterial used in bone tissue engineering.

  9. [Synthesis and characterization of CO-3(2-) doping nano-hydroxyapatite].

    Science.gov (United States)

    Liao, Jian-Guo; Li, Yan-Qun; Duan, Xing-Ze; Liu, Qiong

    2014-11-01

    CO3(2-) doping is an effective method to increase the biological activity of nano-hydroxyapatite (n-HA). In the present study, calcium nitrate and trisodium phosphate were chosen as raw materials, with a certain amount of Na2CO3 as a source of CO-3(2-) ions, to synthesize nano-carbonate hydroxyapatite (n-CHA) slurry by solution precipitation method. The structure and micro-morphology of n-CHA were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR) and Raman spectroscopy (RS). The results revealed that the synthetic n-HA crystals are acicular in nanometer scale and have a crystal size of 20-30 nm in diameter and 60-80 nm in length, which are similar to natural bone apatite. And the crystallinity of n-CHA crystals decreases to the increment of CO3(2-). Samples with more CO3(2) have composition and structure more similar to the bone apatite. The value of lattice parameters a decreases, value of c increases, and c/a value increases with the increase in the amount of CO3(2-), in accordance with crystal cell parameters change rule of type B replacement. In the AB mixed type (substitution OH- and PO4(3-)) CHA, IR characteristic peak of CO3(2-) out-of-plane bending vibration appears at 872 cm(-1), meanwhile, the asymmetry flexible vibration band is split into band at 1 454 cm(-1) and band at 1 420 cm(-1), while weak CO3(2)-peak appears at 1 540 cm(-1). CO3(2-) Raman peak of symmetric stretching vibration appears at 1 122 cm(-1). CO3(2-) B-type (substitution PO4(3-)) peak appeared at 1 071 cm(-1). Through the calculation of integral area ratio of PO4(3-)/ CO3(2-), OH-/CO3(2-), and PO4(3-)/OH-, low quantity CO3(2-) is B-type and high quantity CO3(2-) is A-type (substitution OH-). The results show that the synthesized apatite crystals are AB hybrid substitued nano-carbonate hydroxyapatite, however B-type replacement is the main substitute mode. Due to similarity inthe shape, size, crystal structure

  10. Calcium channel blocker overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used to ...

  11. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  12. Warpage Optimisation on the Moulded Part with Conformal Cooling Channels using Response Surface Methodology (RSM and Glowworm Swarm Optimisation (GSO

    Directory of Open Access Journals (Sweden)

    Hazwan M.H.M.

    2017-01-01

    Full Text Available Today, there are many of optimisation method have been explored by previous researchers to find the appropriate processing parameters setting for the injection moulding process. From the previous researches, it has been proven that the optimisation work improved the quality of the moulded part. However, the application of optimisation work in conformal cooling channels still lacks. Therefore, in this study, the application of optimisation work to improve warpage of front panel housing with conformal cooling channels moulds have been explored. By choosing cooling time, coolant temperature, packing pressure and melt temperature as the variable parameters, design of experiment (DOE has been defined by using the rotatable central composite design (CCD approach. Response Surface Methodology (RSM was performed to determine the mathematical model. The mathematical model then will be used in Glowworm Swarm Optimisation (GSO method in order to obtain the optimal processing parameters setting which will optimise the warpage condition. Based on the results, cooling time is the most significant factor contributes to the warpage condition and warpage have optimised by 38.7% after optimisation using the proposed approach. This finding shows that the application of conformal cooling channels with optimisation work will produce better quality of the moulded part.

  13. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    Science.gov (United States)

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Chifiriuc, Mariana Carmen; Costescu, Adrian; Le Coustumer, Philippe; Predoi, Daniela

    2013-01-01

    The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures. PMID:23509801

  14. Mechanical properties of hydroxyapatite single crystals from nanoindentation data

    Science.gov (United States)

    Zamiri, A.; De, S.

    2011-01-01

    In this paper we compute elasto-plastic properties of hydroxyapatite single crystals from nanindentation data using a two-step algorithm. In the first step the yield stress is obtained using hardness and Young’s modulus data, followed by the computation of the flow parameters. The computational approach is first validated with data from existing literature. It is observed that hydroxyapatite single crystals exhibit anisotropic mechanical response with a lower yield stress along the [1010] crystallographic direction compared to the [0001] direction. Both work hardening rate and work hardening exponent are found to be higher for indentation along the [0001] crystallographic direction. The stress-strain curves extracted here could be used for developing constitutive models for hydroxyapatite single crystals. PMID:21262492

  15. Study of thermal effects of silicate-containing hydroxyapatites

    Science.gov (United States)

    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.

  16. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Carmen Steluta Ciobanu

    2013-01-01

    Full Text Available The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO46(OH2 nanoparticles (Ag:HAp-NPs for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.

  17. [Study on the defluoridation of drinking water with synthetic hydroxyapatite].

    Science.gov (United States)

    Ying, B; Li, X; Cong, Z

    2001-11-01

    Synthetic hydroxyapatite was used as a material for the defluoridation of drinking water. The defluoridation capacity, regeneration the capability of defluoridator and the corresponding parameters of defluoridation and regeneration have been studied with batch and column test. The results showed that the defluoridation capacity of synthetic hydroxyapatite on F- was 3.7-4.3 mg/g in batch test, 5.6 mg/g for break through (1.0 mg/L is considered as the break through point) in column test, and 10.7 mg/g for saturation in column test. The efficiency of regeneration was 46%-64% for saturated hydroxyapatite with surface-coating method.

  18. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  19. Identification of Specific Hydroxyapatite {001} Binding Heptapeptide by Phage Display and Its Nucleation Effect

    Directory of Open Access Journals (Sweden)

    Jing Mao

    2016-08-01

    Full Text Available With recent developments of molecular biomimetics that combine genetic engineering and nanotechnology, peptides can be genetically engineered to bind specifically to inorganic components and execute the task of collagen matrix proteins. In this study, using biogenous tooth enamel as binding substrate, we identified a new heptapeptide (enamel high-affinity binding peptide, EHBP from linear 7-mer peptide phage display library. Through the output/input affinity test, it was found that EHBP has the highest affinity to enamel with an output/input ratio of 14.814 × 10−7, while a random peptide (RP displayed much lower output/input ratio of 0.00035 × 10−7. This binding affinity was also verified by confocal laser scanning microscopy (CLSM analysis. It was found that EHBP absorbing onto the enamel surface exhibits highest normalized fluorescence intensity (5.6 ± 1.2, comparing to the intensity of EHBP to enamel longitudinal section (1.5 ± 0.9 (p < 0.05 as well as to the intensity of a low-affinity binding peptide (ELBP to enamel (1.5 ± 0.5 (p < 0.05. Transmission electron microscopy (TEM, Attenuated total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR, and X-ray Diffraction (XRD studies further confirmed that crystallized hydroxyapatite were precipitated in the mineralization solution containing EHBP. To better understand the nucleation effect of EHBP, EHBP was further investigated on its interaction with calcium phosphate clusters through in vitro mineralization model. The calcium and phosphate ion consumption as well as zeta potential survey revealed that EHBP might previously adsorb to phosphate (PO43− groups and then initiate the precipitation of calcium and phosphate groups. This study not only proved the electrostatic interaction of phosphate group and the genetically engineering solid-binding peptide, but also provided a novel nucleation motif for potential applications in guided hard tissue biomineralization and

  20. Characterization of derived natural hydroxyapatite (HAp) obtained from different types of tilapia fish bones and scales

    Science.gov (United States)

    Fara, A. N. K. A.; Abdullah, H. Z.

    2015-07-01

    Hydroxyapatite, (HAp), Ca10(PO4)6(OH)2, is recognised as a biomaterial that is widely used for bone implant due to its chemical and structural similarity to the mineral components in human bone and enamel. The elements of HAp are primarily composed of calcium and phosphorus molar ratio of calcium to phosphorous is 1.67 capable to promote bone in-growth into prosthetic implant. Enormous amounts of by-product waste produced from fish factories generated an undesirable environmental impact. Thus, this study was conducted to obtain natural biological HAp from different types of tilapia fish bones and scales from fishery waste. Therefore, fish bones and scales can be as cheap source to produce biological HAp for medical applications. For this purpose, fish bones and scales of tilapia fish were boiled at 100°C to remove adhering meat and other impurities. Later, fish bones and scales were separated into several groups and subjected to different calcination temperatures of 800° C and 900° C for 3h respectively. Afterward, all calcined samples were crushed to form a fine powder. The XRD result revealed the presence of derived Hapfrom the samples powder and were identical with standard Hap. Thermo Gravimetric Analysis was carried out to show the thermal stability of the HAp powder from different types of fish bones and scales. SEM results show porous structure appeared in calcined samples compared to raw samples. The findings are the promising alternative to produce calcium and phosphorus from fishery wastes that beneficial to medical applications.

  1. Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application

    Energy Technology Data Exchange (ETDEWEB)

    Kulanthaivel, Senthilguru [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Roy, Bibhas [Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Agarwal, Tarun [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Giri, Supratim [Department of Chemistry, National Institute of Technology, Rourkela, Odisha 769008 (India); Pramanik, Krishna; Pal, Kunal; Ray, Sirsendu S. [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India); Maiti, Tapas K. [Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Banerjee, Indranil, E-mail: indraniliit@gmail.com [Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, Odisha 769008 (India)

    2016-01-01

    ABSTRACT: The present study delineates the synthesis and characterization of cobalt doped proangiogenic–osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co{sup 2+}) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP–OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic–osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering. - Highlights: • Cobalt (Co{sup +2}) doped hydroxyapatite (Co-HAp) can be prepared by the wet chemical method. • The concentration of Co{sup +2} influences the physico-chemical properties of HAp. • Co-HAp was found to be biocompatible and osteogenic. • Co-HAp enhanced cellular VEGF secretion through HIF-1α stabilization. • The optimum biological performance of Co-HAp was achieved for 0.33% (w/w) Co{sup +2} doping.

  2. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  3. Modelling, screening, and solving of optimisation problems: Application to industrial metal forming processes

    NARCIS (Netherlands)

    Bonte, M.H.A.; van den Boogaard, Antonius H.; Veldman, E.

    2007-01-01

    Coupling Finite Element (FEM) simulations to mathematical optimisation techniques provides a high potential to improve industrial metal forming processes. In order to optimise these processes, all kind of optimisation problems need to be mathematically modelled and subsequently solved using an

  4. Waste utilization for the controlled synthesis of nanosized hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Nayar, Suprabha, E-mail: Suprabha.nayar@gmail.com [National Metallurgical Laboratory, Jamshedpur (India); Guha, Avijit [National Metallurgical Laboratory, Jamshedpur (India)

    2009-05-05

    This work uses biomolecules in waste and medicinally important materials for the synthesis of hydroxyapatite nanoparticles. Orange and potato peel, eggshell, papaya leaf and calendula flower extracts have varied biomolecules, which exert a significant, control on the in situ synthesis of nanosized hydroxyapatite particles. The biomimetic synthesis of inorganic particles using known matrices is already well established, however, there are only a few reports using compound extracts. The synthesized nanocomposite has been characterized using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy studies. Role of varied biomolecules in controlled inorganic synthesis may have tremendous technological impact.

  5. Synthesis of Biocompatible Hydroxyapatite Using Chitosan Oligosaccharide as a Template

    Directory of Open Access Journals (Sweden)

    Jinyu Wang

    2015-11-01

    Full Text Available In this study, a novel biocompatible hydroxyapatite (HA was synthesized by using chitosan oligosaccharide (COS as a template. These HA samples were studied by Fourier transform infrared (FTIR spectroscopy, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and transmission electron microscopy (TEM. The biocompatibility of HA samples was evaluated via cell viability, cell morphology and alkaline phosphatase staining of MG-63 cell lines. The results show that HA synthesized in the presence of COS was favorable to proliferation and osteogenic differentiation of MG-63 cells. These hydroxyapatites are potentially attractive biomaterials for bone tissue engineering applications.

  6. Hyperfine interaction measurements in biological compounds: the case of hydroxyapatite; Medidas de interacoes hiperfinas em compostos biologicos: o caso da hidroxiapatita

    Energy Technology Data Exchange (ETDEWEB)

    Leite Neto, Osmar Flavio da Silveira

    2014-07-01

    The use o nanoparticles in current medicine are under intense investigation. The possible advantages proposed by these systems are very impressive and the results may be quite schemer. In this scenario, the association of nanoparticles with radioactive materials (radionuclide) may be the most important step since the discovery of radioactive for nuclear medicine and radiopharmacy, especially for cancer targeting and therapy. The hyperfine interaction of the nuclear probe {sup 111}Cd in the Hydroxyapatite compounds has been investigated by perturbed angular correlation (PAC) spectroscopy in room temperature for the hydroxyapatite made in the temperatures of 90°C, 35°C and with Ho doped, both thermalized and not. The thermalized samples were heated to T= 1273 K for 6 h. The {sup 111}Cd was broadcast in the structure of the material by diffusion, closing in quartz tubes were heated – together with the radioactive PAC probe {sup 111}In/{sup 111}Cd to T = 1073 K for 12 h. In not thermalized samples the PAC spectra indicate a distribution of frequency, but in the thermalized samples, the PAC spectra shows the presence of β-tri calcium phosphate in the structure of this kind of Hydroxyapatite. (author)

  7. Optimisation and characterisation of parabolic membrane mirrors

    Science.gov (United States)

    Hellmuth, T.; Khrennikov, K.; Kronast, W.; Huster, R.; Mescheder, U.

    2008-04-01

    MOEMS-based thin silicon membrane mirrors with a useable diameter of 5mm and fast (up to 1kHz) tunable focal length (80 mm to 1m) have been realized. A ring shaped counter electrode is used to achieve a parabolic membrane deformation by electrostatic forces. A circular kerf at the outer perimeter of the membrane provides a soft suspension to the rim and thus reduces the needed driving voltage. FEM has been used for optimisation of the design, especially of the soft suspension, which is realized by a controlled thinning of the outer rim of the Si-membrane. A critical issue for demanding applications is the membrane distortion induced by material stress and the fabrication process. Membrane residual stress reduction has been obtained by using SOI-technology (c-silicon) and by optimisation of the Al deposition process (Al-coated Si-membrane). For dynamic tests of the optical mirror properties a stroboscopic interferometer has been realized. A pulsed laser diode with a pulse duration of 10μs is used as a light source which is synchronized with the modulated electrical field driving the membrane mirror. The interference pattern is recorded with a CCD and evaluated with conventional phaseshift techniques. The geometry is similar to a Mach-Zehnder interferometer. The reference path length can be varied with a piezoceramic to induce the phase shift.

  8. Bloodstain pattern analysis as optimisation problem.

    Science.gov (United States)

    Vitiello, Autilia; Di Nunzio, Ciro; Garofano, Luciano; Saliva, Maurizio; Ricci, Pietrantonio; Acampora, Giovanni

    2016-09-01

    Bloodstain pattern analysis (BPA) is an approach to support forensic investigators in reconstructing the dynamics of bloody crimes. This forensic technique has been successfully applied in solving heinous and complex murder cases around the world and, recently, computer-based BPA approaches have been designed to better support investigators both in terms of speed and quality of analysis. However, despite its widespread use, current automatic techniques for BPA try to define some algorithmic steps to replicate a sequence of subjective investigators' tasks without relying on any mathematical formalism to compute an objective reconstruction of the crime. The lack of an objective mathematical foundation is a critical issue in a scenario where the quality of evidences can strongly affect a court trial and the life of people involved in that trial. This paper introduces the very first formal representation of BPA by means of an optimisation problem, on which to base the next generation of crime reconstruction techniques. As an example of the benefits provided by the proposed formal representation of BPA, a case study based on a genetic algorithm shows how the BPA optimisation problem can support investigators in performing a fast, precise, automatic and objective analysis. Copyright © 2016. Published by Elsevier Ireland Ltd.

  9. Ant Colony Optimisation for Backward Production Scheduling

    Directory of Open Access Journals (Sweden)

    Leandro Pereira dos Santos

    2012-01-01

    Full Text Available The main objective of a production scheduling system is to assign tasks (orders or jobs to resources and sequence them as efficiently and economically (optimised as possible. Achieving this goal is a difficult task in complex environment where capacity is usually limited. In these scenarios, finding an optimal solution—if possible—demands a large amount of computer time. For this reason, in many cases, a good solution that is quickly found is preferred. In such situations, the use of metaheuristics is an appropriate strategy. In these last two decades, some out-of-the-shelf systems have been developed using such techniques. This paper presents and analyses the development of a shop-floor scheduling system that uses ant colony optimisation (ACO in a backward scheduling problem in a manufacturing scenario with single-stage processing, parallel resources, and flexible routings. This scenario was found in a large food industry where the corresponding author worked as consultant for more than a year. This work demonstrates the applicability of this artificial intelligence technique. In fact, ACO proved to be as efficient as branch-and-bound, however, executing much faster.

  10. Air bending process for load optimised profiles

    Energy Technology Data Exchange (ETDEWEB)

    Abratis, C.; Hirt, G.; Kopp, R. [Inst. of Metal Forming, RWTH Univ., Aachen (Germany)

    2006-09-15

    In this paper the air bending of tailor rolled blanks (TRB) to load optimised profiles is investigated. A new flexible modular tool system has been developed in order to locally adapt the die height to the spring back which is more pronounced in thinner areas in comparison to thicker areas of the TRB. With the new tool system the dies can be modulated according to the thickness distribution of the tailor rolled blank, whereas the amount of die lifting depends on the thickness difference and the corresponding variance of mechanical properties. In bending tests with several specimens having a constant thickness a linear relation between the increasing part angle and a stepwise increased die lifting was observed. With this linear dependency the amount of die lifting can be calculated and thus applied on bending of TRB. Special consideration is required for the die adjustment in the area of the linear thickness transition, therefore three different die arrangements have been investigated. The results of different bending tests are compared and evaluated in order to apply the new technique to form a new car body floor structure in profile intensive construction. By using load optimised profiles in combination with a steel 22MnB5 which has been heat-treated at defined sections the survival space of a car passenger in a side pole impact has been enormously increased by more than 40%. (orig.)

  11. Noise aspects at aerodynamic blade optimisation projects

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, J.G. [Netherlands Energy Research Foundation, Petten (Netherlands)

    1997-12-31

    This paper shows an example of an aerodynamic blade optimisation, using the program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. The aerodynamic optimised geometry from PVOPT is the `real` optimum (up to the latest decimal). The most important conclusion from this study is, that it is worthwhile to investigate the behaviour of the objective function (in the present case the energy yield) around the optimum: If the optimum is flat, there is a possibility to apply modifications to the optimum configuration with only a limited loss in energy yield. It is obvious that the modified configurations emits a different (and possibly lower) noise level. In the BLADOPT program (the successor of PVOPT) it will be possible to quantify the noise level and hence to assess the reduced noise emission more thoroughly. At present the most promising approaches for noise reduction are believed to be a reduction of the rotor speed (if at all possible), and a reduction of the tip angle by means of low lift profiles, or decreased twist at the outboard stations. These modifications were possible without a significant loss in energy yield. (LN)

  12. Preparation and characterization of surface-modified calcium hydrogenphosphate by hexamethylene diisocyanates.

    Science.gov (United States)

    Dong, G C; Lin, F H; Yao, C H; Jiang, G J; Huang, C W

    2000-01-01

    Isocyanate group has been reported as a coupling agent of hydroxyapatite and polymers. The studies showed that the isocyanate would react with hydroxyl groups of hydroxyapatite and form a covalent bond between isocyanate and hydroxyapatite. In the study, hexamethlene diisocyanate (HMDI) was used as coupling agent. Calcium hydrogen-phosphate (CaHPO4, CHP) powders was the candidate ceramic due to higher content of hydroxyl group, which would react with HMDI at the temperature of 30, 40, 50, 60, and 70 degrees C for 4 hours. Dibutyltin dilaurate and hydroquinone were used as catalyst and inhibitor, respectively. The product was analyzed by DTA, TGA, FTIR, XRD, 13C solid state NMR and 31P, 13C liquid state NMR. From the results, we could prove the surface of calcium hydrogen-phosphate has been successfully modified. The largest amount (5.6 wt%) of HMDI could be grafted on the surface of CHP when reacted at 50 degrees C for 4 hours. Some chain extension could be observed and their structure would also be described in the research.

  13. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

    Directory of Open Access Journals (Sweden)

    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  14. Real-time optimisation of the Hoa Binh reservoir, Vietnam

    DEFF Research Database (Denmark)

    Richaud, Bertrand; Madsen, Henrik; Rosbjerg, Dan

    2011-01-01

    Multi-purpose reservoirs often have to be managed according to conflicting objectives, which requires efficient tools for trading-off the objectives. This paper proposes a multi-objective simulation-optimisation approach that couples off-line rule curve optimisation with on-line real-time optimis...

  15. A comparison between optimisation algorithms for metal forming processes

    NARCIS (Netherlands)

    Bonte, M.H.A.; Do, T.T.; Fourment, L.; van den Boogaard, Antonius H.; Huetink, Han; Habbal, A.

    2006-01-01

    Coupling optimisation algorithms to Finite Element (FEM) simulations is a very promising way to achieve optimal metal forming processes. However, many optimisation algorithms exist and it is not clear which of these algorithms to use. This paper compares an efficient Metamodel Assisted Evolutionary

  16. Aerodynamic shape parameterisation and optimisation of novel configurations

    NARCIS (Netherlands)

    Straathof, M.H.; Van Tooren, M.J.L.; Voskuijl, M.; Koren, B.

    2008-01-01

    The Multi-Disciplinary Design Optimisation (MDO) process can be supported by partial automation of analysis and optimisation steps. Design and Engineering Engines (DEE) are useful concepts to structure this type of automation. Within the DEE, a product can be parameterically defined using Knowledge

  17. Water quality modelling and optimisation of wastewater treatment ...

    African Journals Online (AJOL)

    2016-10-04

    Oct 4, 2016 ... Using this model, it was demonstrated that water quality standards can be met at all monitoring points at a minimum cost by simultaneously optimising treatment levels at each treatment plant. Keywords: instream water quality, mixed integer optimisation, wastewater treatment levels, Streeter-Phelps.

  18. application of ant colony optimisation in distribution transformer sizing

    African Journals Online (AJOL)

    HP

    E-mail addresses: 1 folorunsoo@abuad.edu.ng, 2 patrick.oriaifo@uniben.edu, 3 neville.idiagi@uniben.edu,. 4 emma.ogujor@uniben.edu.ng. ABSTRACT. This study proposes an optimisation method for transformer sizing in power system using ant colony optimisation and a verification of the process by MATLAB software.

  19. Application of ant colony optimisation in distribution transformer sizing

    African Journals Online (AJOL)

    This study proposes an optimisation method for transformer sizing in power system using ant colony optimisation and a verification of the process by MATLAB software. The aim is to address the issue of transformer sizing which is a major challenge affecting its effective performance, longevity, huge capital cost and power ...

  20. Kriging based robust optimisation algorithm for minimax problems in electromagnetics

    Directory of Open Access Journals (Sweden)

    Li Yinjiang

    2016-12-01

    Full Text Available The paper discusses some of the recent advances in kriging based worst-case design optimisation and proposes a new two-stage approach to solve practical problems. The efficiency of the infill points allocation is improved significantly by adding an extra layer of optimisation enhanced by a validation process.