Mechanical Performance and In Vitro Studies of Hydroxyapatite/Wollastonite Scaffold for Bone Tissue Engineering

2011 ◽  
Vol 493-494 ◽  
pp. 855-860
Author(s):  
Sanosh Kunjalukkal Padmanabhan ◽  
Marina Carrozzo ◽  
Francesca Gervaso ◽  
Francesca Scalera ◽  
Alessandro Sannino ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Compressive Strength ◽  
Mechanical Performance ◽  
Weight Ratio ◽  
Fold Increase ◽  
In Vitro Bioactivity ◽  
Phase Purity ◽  
Before And After ◽  
Highly Porous

A highly porous (~90%) interconnected hydroxyapatite/wollastonite (HA/WS) scaffolds were prepared by polymeric sponge replica method using a slurry containing HA:Calcium silicate in the weight ratio of 50:50 and sintered at 1300 °C. The phase purity of the scaffolds were analyzed by using XRD. The pore size, pore structure, microstructure and elemental analysis of the scaffolds before and after SBF soaking were analyzed using SEM and EDS. In-vitro bioactivity and bioresorbability confirmed the feasibility of the developed scaffolds. The HA/WS scaffold shows two fold increase in the compressive strength compared to pure HA scaffold.

scholarly journals Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

2019 ◽  
Vol 8 (2S8) ◽  
pp. 883-887
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Before And After ◽  
Alkaline Conditions ◽  
Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

Intermittent, Repetitive Corticosteroid-Induced Upregulation of Platelet Levels After Adenovirus-Mediated Transfer to the Liver of a Chimeric Glucocorticoid-Responsive Promoter Controlling the Thrombopoietin cDNA

Blood ◽  
1998 ◽  
Vol 92 (3) ◽  
pp. 822-833 ◽  
Author(s):  
Ko Narumi ◽  
Motoyoshi Suzuki ◽  
Wenru Song ◽  
Malcolm A.S. Moore ◽  
Ronald G. Crystal
Keyword(s):  
Clinical Medicine ◽  
Intraperitoneal Administration ◽  
Fold Increase ◽  
Inducible Promoter ◽  
Pharmacologic Agent ◽  
Before And After ◽  
American Society ◽  
Pharmacologic Agents

Abstract For many in vivo gene therapy clinical applications, it is desirable to control the expression of the transferred transgene using pharmacologic agents. To evaluate the feasibility of accomplishing this using corticosteroids, pharmacologic agents widely used in clinical medicine, we constructed replication deficient adenoviral (Ad) vectors containing an expression cassette with a chimeric promoter comprised of five glucocorticoid response elements (GRE) and the chloramphenicol acetyltransferase reporter gene (AdGRE.CAT) or the murine thrombopoietin cDNA (AdGRE.mTPO). In vitro studies showed the vectors functioned as expected, with marked glucocorticoid-induced upregulation of the CAT or mTPO transgenes. To evaluate the inducibility of the GRE promoter in vivo, the AdGRE.CAT vector was administered intravenously to C57B1/6 mice, and CAT activity was quantified in liver before and after intraperitoneal administration of dexamethasone. The GRE promoter activity was dependent on the dexamethasone dose, with a 100-fold increase in CAT expression with 50 μg dexamethasone, similar to the levels observed in vivo with the Rous sarcoma virus long terminal repeat constitutive promoter. After dexamethasone administration, maximum CAT activity was observed at day 2, with a slow decline to baseline levels by 2 weeks. Based on these observations, we hypothesized that a single administration of an Ad vector-mediated transfer of the chimeric GRE inducible promoter driving the mTPO cDNA would enable repetitive administration of corticosteroids to repetitively upregulate platelet levels for 1 to 2 weeks. The data show that this occurs, with dexamethasone administration every 3 weeks associated with 1-week elevations (at each 3-week interval) of serum mTPO levels, megakaryocyte numbers in bone marrow, and platelet levels fourfold to sixfold over baseline. Thus, with the appropriate promoter, it is possible to use a commonly used pharmacologic agent to upregulate the expression of a newly transferred gene on demand. © 1998 by The American Society of Hematology.

Comparative Evaluation of the Bioactive Behavior of HA and ZrO2 Reinforced Coatings

2011 ◽  
Vol 493-494 ◽  
pp. 447-452
Author(s):  
George Theodorou ◽  
Ourania Menti Goudouri ◽  
Lambrini Papadopoulou ◽  
Nikolaos Kantiranis ◽  
Subramaniam Yugeswaran ◽  
...  
Keyword(s):  
Steel Substrate ◽  
In Vitro Bioactivity ◽  
Biological Fixation ◽  
Metal Implants ◽  
Ha Coating ◽  
Biological Responses ◽  
Before And After ◽  
Sbf Solution ◽  
Plasma Sprayed

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely investigated as the HA coating can achieve the firm and direct biological fixation with the surrounding bone tissue. It is shown in previous studies that the mechanical properties of HA coatings are improved by the addition of ZrO2 particles during the deposition of the coating on the substrate. Subsequently, the cohesive and adhesive strengths of plasma-sprayed hydroxyapatite (HA) coatings were strengthened by the ZrO2 particles addition as a reinforcing agent in the HA coating (HA+ZrO2 composite coating). The aim of the present work is to investigate and evaluate the in vitro bioactivity assessment of HA and HA/ZrO2 coatings, on stainless steel substrate, soaked in c-SBF, in order to study and compare their biological responses. The coatings were produced using vapor plasma spraying (VPS). The characterization of the surface of the coatings before and after soaking in SBF solution was performed using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction analysis (XRD). All samples were smoothed before insertion in the medium and the in vitro bioactivity of all coating samples was tested in conventional Simulated Body Fluid (c-SBF) solution for various immersion times.

scholarly journals In vitro bioactivity of Polyurethane/85S Bioglass composite scaffolds

2013 ◽  
Vol 11 (9) ◽  
pp. 1439-1446 ◽  
Author(s):  
Lachezar Radev ◽  
Darina Zheleva ◽  
Irena Michailova
Keyword(s):  
Sol Gel ◽  
Spherical Particles ◽  
Polymerization Reaction ◽  
In Vitro Test ◽  
In Vitro Bioactivity ◽  
Before And After ◽  
Vitro Test ◽  
Sbf Solution ◽  
Static Conditions

AbstractIn the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with different content of BG (10 and 20 mol.%) as filler. The 85S Bioglass was synthesized via polystep sol-gel method. The chemical composition of BG is 85SiO2-10CaO-5P2O5 (wt.%). The synthesis of PU was carried out by a two-step polyaddition reaction. The 85S BG was added in situ during the polymerization reaction. In vitro bioactivity of the prepared composites was examined in the presence of 1.5 SBF for 7 days in static conditions. The structure of synthesized PU/BG composites before and after in vitro test was determined by XRD, FTIR and SEM. XRD of the samples before in vitro test proved that the phase of γCa2P2O7 in the PU/20BG is visible. FTIR revealed the presence of urethane bond between OH-(from BG) and NCO groups (from PU). Based on FTIR results after in vitro test in 1.5 SBF solutions, A/B-carbonate containing hydroxyapatite (CO3HA) was formed. XRD proved that HA was formed on the surface of the samples, but Ca2P2O7 does not undergo any changes in the 1.5 SBF solution. SEM depicted the nano-HA agglomerated in spherical particles after immersion in 1.5 SBF for 7 days.

Preparation and Characterization of Ha/Gel/β-TCP Microspheres Composite Porous Scaffold

2018 ◽  
Vol 782 ◽  
pp. 103-115
Author(s):  
Yang Zi Zhao ◽  
You Fa Wang
Keyword(s):  
Tissue Engineering ◽  
Compressive Strength ◽  
Hyaluronic Acid ◽  
Pore Size ◽  
Porous Scaffold ◽  
Three Dimensional ◽  
Swelling Ratio ◽  
Cell Compatibility ◽  
Hydrogel Scaffolds

Being one of the three elements of tissue engineering, three-dimensional porous structure scaffold plays an important role in tissue engineering. As it not only prvovide cells for the life, but also serves as a template to guide tissue regeneration and control of organizational structure and other functions. In this study, hyaluronic acid and gelatin are successfully cross-linked by 1-ethyl- (3-dimethylaminopropyl) -carbodiimide hydrochloride (EDC) , and compound β-TCP microspheres to prepare porous hydrogel scaffolds. The microspheres were analyzed by X-ray diffraction (XRD). The scaffolds were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). At the same time, the compressive strength, swelling ratio, degradation of the scaffold were tested. To assess the in vitro cell compatibility of the scaffolds, mouse L929 fibroblasts were seeded onto scaffolds for cell morphology and cell viability studies. The results showed that the pore size of the porous scaffold can be adjusted by changing the ratio of gelatin to hyaluronic acid (HA), increasing the proportion of hyaluronic acid in a certain range, pore size will be significantly increased. With the increase of the proportion of hyaluronic acid in the scaffold, the swelling ratio and the degradation rate also increased. The compressive strength of the scaffold increased with the increase of the proportion of gelatin. The appropriate ratio of β-TCP can promote cell growth and proliferation.

scholarly journals Synthesis of poly(vinyl alcohol) — hydroxyapatite composites and characterization of their bioactivity

2013 ◽  
Vol 11 (9) ◽  
pp. 1403-1411 ◽  
Author(s):  
Zuzana Balgová ◽  
Martin Palou ◽  
Jaromír Wasserbauer ◽  
Jana Kozánková
Keyword(s):  
Vinyl Alcohol ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Weight Percent ◽  
Poly Vinyl Alcohol ◽  
Aqueous Environment ◽  
Calcium Nitrate Tetrahydrate ◽  
In Vitro Bioactivity ◽  
Before And After

AbstractAbstract A series of poly(vinyl alcohol) membranes reinforced with hydroxyapatite in various weight percent — 0%, 10%, 20%, 30%, 40% and 50% were prepared. Hydroxyapatite was prepared by a sol-gel procedure using diammonium hydrogen phosphate and calcium nitrate tetrahydrate as starting materials in an alkaline aqueous environment and then mixed with a solution of poly(vinyl alcohol), which was prepared by dissolving it in water at 85°C. The different mixtures were cast in a mould and evaporated for 7 days at a temperature of 30°C to obtain 1 mm thin membranes. FTIR spectroscopy was used to identify the different functional groups in the composites. The surface morphology was examined using a scanning electron microscope. In vitro bioactivity tests in Simulated Blood Fluid were performed for up to 28 days, especially for the membrane containing 50 wt.% HA. SEM was used to characterise the surface microstructure of biocomposite membranes before and after soaking in SBF. It was observed that the formation of clusters in membranes increases with increasing amount of HA. The clusters are formed due to agglomeration and crystal growth of HA particles during drying of the membranes. The in vitro bioactivity was found to increase with soaking time of biocomposite materials in simulated blood fluid. Graphical abstract

Calcium Phosphate Biomaterials Composite Device: In-Vitro and In-Vivo Investigation

2007 ◽  
Vol 330-332 ◽  
pp. 835-838
Author(s):  
Aliassghar Tofighi ◽  
M. Sutaria
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Calcium Phosphate ◽  
Powder Processing ◽  
Mechanical Performance ◽  
Processing Parameters ◽  
Allograft Bone ◽  
Nano Structure

Low crystalline apatite (LCA) and calcium phosphate cements (CPC) based on amorphous calcium phosphate and dicalcium phosphate dihydrate (1 to 1 ratio) were combined with bioresorbable PLGA copolymer (0 to 20 wt.%) for preparation of solid-formed devices. A pilot manufacturing based on powder processing techniques using isostatic pressure (44,000 psig) was conducted. Processing parameters such as isostatic pressure, temperature, times and device dimension were varied to achieve appropriate mechanical properties comparable to that of allograft bone dowel used as a gold standard in clinical application. The solid-form devices were characterized for physico-chemical and mechanical performance, as well as subjected to an in-vitro wet environment incubation at body temperature (37°C). Fluid diffusion was investigated to evaluate the fluid absorption (through microporosity) and the compressive strength of wet devices vs. incubation time (up to 30 days) was also studied. The shear strength and compressive strength of pure LCA dowels was respectively 26 and 122 MPa, which corresponds to a process densification of about 30%. The compressive strength was dramatically improved with addition of various amounts of copolymer. The maximum compressive strength of 180 MPa was obtained for dowels containing 10 wt.% copolymer. Calcium phosphate composite also increased the shear strength to about 42 MPa. These mechanical performances were significantly higher than that of allograft bone dowel (MD-II™), reported about 10 MPa. A pilot sheep interbody fusion of lumbar spine (L3/L4 and L4/L5) demonstrates mechanical integrity and intervertebral fusion at 6 months. LCA was found to be the most suitable CaP material because of its biocompatibility, chemical composition, nano-structure and high specific surface area that exhibits in-vivo biointegrity and cell mediated process.

scholarly journals Synthesis and Investigation into Apatite-forming Ability of Hydroxyapatite/Chitosan-based Scaffold

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Tran Thanh Hoai ◽  
Nguyen Kim Nga
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Inorganic Material ◽  
Porous Scaffolds ◽  
Mineral Layer ◽  
Chitosan Scaffold ◽  
Apatite Mineral ◽  
Highly Porous

In this study, porous scaffolds were fabricated using inorganic material-hydroxyapatite and chitosan for bone-tissue engineering. The combination of hydroxyapatite and chitosan may result in increasing biocompatibility of the scaffolds. The scaffolds were prepared by solvent casting and paticulate leaching method. Bioactivity of the scaffolds was evaluated through in vitro experiments by soaking scaffold samples in simulated body fluid (SBF). The scaffolds obtained were highly porous and interconnected with a mean pore size of around 200µm and porosity about 79 %. The apatite-mineral layer was produced on the HAp/chitosan after 10 days of soaking in SBF, however, it was not observed on the chitosan scaffold after 10 days soaking. The results revealed that the HAp/chitosan scaffold showed better bioactivity than the chitosan scaffold. Keywords Scaffold, Chitosan, Apatite, SBF. In this study, porous scaffolds were fabricated using inorganic material-hydroxyapatite and chitosan for bone-tissue engineering. The combination of hydroxyapatite and chitosan may result in increasing biocompatibility of the scaffolds. The scaffolds were prepared by solvent casting and paticulate leaching method. Bioactivity of the scaffolds was evaluated through in vitro experiments by soaking scaffold samples in simulated body fluid (SBF). The scaffolds obtained were highly porous and interconnected with a mean pore size of around 200µm and porosity about 79 %. The apatite-mineral layer was produced on the HAp/chitosan after 10 days of soaking in SBF, however, it was not observed on the chitosan scaffold after 10 days soaking. The results revealed that the HAp/chitosan scaffold showed better bioactivity than the chitosan scaffold. Keywords: Scaffold, Chitosan, Apatite, SBF.   In this study, porous scaffolds were fabricated using inorganic material-hydroxyapatite and chitosan for bone-tissue engineering. The combination of hydroxyapatite and chitosan may result in increasing biocompatibility of the scaffolds. The scaffolds were prepared by solvent casting and paticulate leaching method. Bioactivity of the scaffolds was evaluated through in vitro experiments by soaking scaffold samples in simulated body fluid (SBF). The scaffolds obtained were highly porous and interconnected with a mean pore size of around 200µm and porosity about 79 %. The apatite-mineral layer was produced on the HAp/chitosan after 10 days of soaking in SBF, however, it was not observed on the chitosan scaffold after 10 days soaking. The results revealed that the HAp/chitosan scaffold showed better bioactivity than the chitosan scaffold. Keywords: Scaffold, Chitosan, Apatite, SBF. References [1] M.P. Bostrom, D.A. Seigerman, The clinical use of allografts, demineralized bone matrices, synthetic bone graft substitutes and osteoinductive growth factors: a survey study, Hss. Journal 1 (2005) 9-18. https://doi.org/10. 1007/s11420-005-0111-5.[2] T.T. Hoai, N.K Nga, L.T. Giang, T.Q. Huy, P.N.M. Tuan, B.T.T. Binh, Hydrothermal Synthesis of Hydroxyapatite Nanorods for Rapid Formation of Bone-Like Mineralization, J. Electron. Mater. 46 (2017) 5064-5072. https:// doi.org/10.1007/s11664-017-5509-6.[3] M. Rinaudo, Chitin and chitosan: properties and applications, Prog. Polym. Sci. 31 (2006) 603-632. https://doi.org/10.1016/j.progpolymsci.2006. 06.001.[4] N.K. Nga, H.D. Chinh, P.T.T Hong, T.Q. Huy, Facile chitosan films for high performance removal of reactive blue 19 dye from aqueous solution, J. Polym. Environ. 25 (2007) 146-155. https://doi.org/10.1007/s10924-016-0792-5.[5] M.N.V Ravi Kumar, R.A.A Muzzarelli, H. Sashiwa, A.J. Domb, Chitosan chemistry and pharmaceutical perspectives, Chem. Rev. 104 (2004) 6017-6084. https://doi.org/10.1021/cr03 0441b.[6] J.M. Karp, M.S. Shoichet, J.E. Davies, Bone formation on two‐dimensional poly (DL‐lactide‐co‐glycolide)(PLGA) films and three‐dimensional PLGA tissue engineering scaffolds in vitro, J. Biomed. Mater. Res. A 64 (2003) 388-396. https://doi.org/10.1002/jbm.a.10420.[7] J.F. Mano, R.L. Reis, Osteochondral defects: present situation and tissue engineering approaches, J. Tissue. Eng. Regen. Med. 1 (2007) 261-273. https://doi.org/10.1002/term.37. [8] A.G. Mikos, J.S. Temenoff, Formation of highly porous biodegradable scaffolds for tissue engineering, Electron. J. Biotechn. 3 (2000) 23-24. http://dx.doi.org/10.4067/S0717-3458200000 0200003.[9] W.W. Thein-Han, R.D.K Misra, Biomimetic chitosan–nanohydroxyapatite composite scaffolds for bone tissue engineering, Acta Biomater. 5 (2009) 1182–1197. https://doi.org/ 10.1016/j.actbio.2008.11.025.[10] Y. Zhang, J.R. Venugopal, A.E. Turki, S. Ramakrishna, B. Su, C.T. Lim, Electrospun biomimetic nanocomposite nanofibers of hydroxyapatite/chitosan for bone tissue engineering, Biomaterials 29 (2008) 4314–4322. https://doi.org/10.1016/j.biomaterials.2008.07.038.[11] B.X. Vương, Tổng hợp và đặc trưng vật liệu composite hydroxyapatite/chitosan ứng dụng trong kỹ thuật y sinh.,Tạp chí Khoa học ĐHQGHN: Khoa học Tự nhiên và Công nghệ Tập 34 (2018) 9-15. https://doi.org/10.25073/ 2588-1140/vnunst.4689.[12] N.K. Nga, T.T. Hoai, P.H. Viet, Biomimetic scaffolds based on hydroxyapatite nanorod/poly (D, L) lactic acid with their corresponding apatite-forming capability and biocompatibility for bone-tissue engineering, Colloids Surf. B Biointerf. 128 (2015) 506-514. https://doi.org/10. 1016/j.colsurfb.2015.03.001.[13] N.K. Nga, L.T. Giang, T.Q. Huy, C. Migliaresi, Surfactant-assisted size control of hydroxyapatite nanorods for bone tissue engineering, Colloids Surf. B: Biointerf. 116 (2014) 666-673. https://doi.org/10.1016/j.colsurfb.2013.11.001.[14] C.R. Kothapalli, M.T. Shaw, M. Wei, Biodegradable HA-PLA 3-D porous scaffolds: effect of nano-sized filler content on scaffold properties, Acta Biomater. 1 (2005) 653-662. https://doi.org/10.1016/j.actbio.2005.06.005.[15] T. Kokubo, H. Takadama, How useful is SBF in predicting in vivo bone bioactivity?, Biomaterials 27 (2006) 2907-2915. https://doi.org/10.1016/j. biomaterials.2006.01.017[16] T.T. Hoai, N.K. Nga, Effect of pore architecture on osteoblast adhesion and proliferation on hydroxyapatite/poly (D, L) lactic acid-based bone scaffolds, J. Iran. Chem. Soc. 15 (2018) 1663-1671. https://doi.org/10.1007/s13738-018-1365-4.        

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