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    Bioactive layer formation on alkaline-acid treated titanium in simulated body fluid

    , Article Materials and Design ; Volume 28, Issue 7 , 2007 , Pages 2154-2159 ; 02613069 (ISSN) Yousefpour, M ; Afshar, A ; Chen, J ; Zhang, X ; Sharif University of Technology
    Elsevier Ltd  2007
    Porous surface on titanium induces apatite formation in simulated body fluid (SBF). This work shows alkaline, acid and polishing treatment, which lead to create apatite coating. Specimens were soaked in 5 M solution of NaOH, 85% HCl-6% HF-9% H3PO4 and 2% HF-4% HNO3-94% H2O. Also many samples were polished with sandpaper. Specimens treated under the above conditions were soaked in simulated body fluid (SBF) for 5 days. Apatite formed within 5 days. The evaluation of Ca/P ratio of samples were made by EDAX analysis to get information of the Ca/P ratio. The values obtained for the apatite were in the range of 1.55, which is near to the stoichiometric value of apatite, for the sample, which was... 

    Manufacturing and Characterization of Bone Scaffold Based on TCP

    , M.Sc. Thesis Sharif University of Technology Gorgin Karaji, Zahra (Author) ; Bagheri, Reza (Supervisor)
    Bone scaffolds are combinations of several materials, for achieving suitable properties and usage for replacing with defected bone. In this study, TCP/Agarose scaffolds are fabricated by two different approaches. The first one is using polymer sponge and gel casting technique and the other one is using foaming agent in order to obtain scaffolds with same porosity. The results show that in spite of same structure and porosity, scaffolds have different mechanical properties due to their different morphologies. Compressive strength of the scaffolds which were fabricated using polymer sponge method is 2.25MPa and elastic modulus is 56.8MPa. After coating with Agarose, compressive strength... 

    Hydroxy Apatite/Titania Nanostructure Biocoating on Ti-6Al-4V Alloy by Sol-Gel Dip-Coating

    , M.Sc. Thesis Sharif University of Technology Dabir, Fatemeh (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Ceramic coatings on metallic substrates are used in many different applications. In biomaterials science, hydroxyapatite coating due to its similarity to the mineral part of bone structure is used to modification of implants surface. In this research, the HA/TiO2 double layer was coated on Ti-6Al-4V by sol- gel dip-coating method. After preparation of stable TiO2 sol, the Ti-6Al-4V substrate was dipped into the TiO2 sol. The speed of dipping was 10cm/min. After drying at 80°C, the TiO2 layer heat-treated at different temperature (350-500°C) for 1h. The HA outer layer was coated by dipping of Ti-6Al-4V substrate with TiO2 layer into HA sol, followed by heat-treatment at different temperatures... 

    Micro Arc Oxidation Coating on Magnesium Alloy AZ31 and Study its CorrosionBehavior in Physiological Solution

    , M.Sc. Thesis Sharif University of Technology Salami, Behrooz (Author) ; Afshar, Abdollah (Supervisor)
    Magnesium and its alloys have been used as biodegradable implements in recent years. However Magnesium implements may corrode in the body before the natural healing process of the damaged tissue. MAO process was studied in order to reduce primary corrosion of Magnesium alloy in Simulated Body Fluid (SBF). MAO coating was created on AZ31 alloy in a nontoxic alkaline-silicate solution at DC current densities of 5, 10, 15 and 20 mA/cm2 for 30 minutes and the current was in form of 20-10-5 mA/cm2 steps that each were applied for 10 minutes. The maximum corrosion resistance was observed for the mentioned step applied current in a 30g/l Sodium Silicate solution. Furthermore the effects of adding... 

    Bioactivity of Surface Modified Titanium Alloy Ti-6Al-4V ELI by Pack Siliconizing in Simulated Body Fluid

    , M.Sc. Thesis Sharif University of Technology Rezvani, Alireza (Author) ; Ekrami, Ali Akbar (Supervisor) ; Ziaei Moayyed, Ali Akbar (Supervisor)
    Titanium alloy Ti-6Al-4V ELI with high biocompatibility and corrosion resistance, has a lot of applications in biomedical engineering. Disadvantage of this alloy is it’s disability to create a fast and good contact with the host/bone environment, after implanting in the body. Beside that it has low wear resistance. Nowadays to optimize the wear resistance, bioactivity and osteoconduction of surface of implants which are made from this alloy, the surface morphology are optimized in size and distribution. Different surface treatments are used for producing rough and porous surfaces to improve bioactivity along with wear resistance. In this study, surface modification of Ti-6Al-4V ELI was done... 

    Biomimetic synthesis of calcium phosphate materials on alkaline-treated titanium

    , Article 29th Annual International Conference of IEEE-EMBS, Engineering in Medicine and Biology Society, EMBC'07, Lyon, 23 August 2007 through 26 August 2007 ; 2007 , Pages 5853-5856 ; 05891019 (ISSN) ; 1424407885 (ISBN); 9781424407880 (ISBN) Salemi, H ; Behnamghader, A ; Afshar, A ; Ardeshir, M ; Forati, T ; Sharif University of Technology
    The hydroxyapatite coating on metal implants is a suitable method to create a bioactive surface and to increase the bone-implant bonding strength. In this research, at first the titanium surface was treated with NaOH solutions ; 5N and 10N at 60°C for 24 h and 5N at 60°C for 24 h followed by heating at 600°C for 1 h. The samples were immersed in the simulated body fluid (SBF) for 28 days to generate a calcium phosphate coating on titanium substrates. The modified substrates and coatings were characterized using SEM and XRD. According to the results obtained in this work the concentration increase of the NaOH solution has influenced the grain boundaries, whereas the heat treatment at 600°C... 

    In vitro characterization of carbon-nanotube-reinforced hydroxyapatite composite coating on 316L stainless steel

    , Article Journal of Ceramic Science and Technology ; Volume 4, Issue 3 , August , 2013 , Pages 163-168 ; 21909385 (ISSN) Mohamadi, S. P ; Nemati, A ; Sadeghian, Z ; Sharif University of Technology
    This investigation focused on a comparison between hydroxyapatite (HA) and carbon-nanotube-reinforced hydroxyapatite composite (CNTs/HA) coatings. The HA and CNTs/HA composite (with 5wt% CNTs) coatings were prepared with the sol-gel method on 316L stainless steel. Phase evaluation by means of XRD and Raman spectroscopy was performed on the HA and CNTs/HA composite coatings. The coatings were immersed in simulated body fluid (SBF) in order to evaluate the biological properties of the coatings. During the first week of immersion, the increase in the amount of Ca2+ precipitation in the SBF when CNTs/HA was used was lower than for the HA coatings. This behavior can be related to the difference... 

    Effect of TiO2 morphology on in vitro bioactivity of polycaprolactone/TiO2 nanocomposites

    , Article Materials Letters ; Volume 65, Issue 15-16 , 2011 , Pages 2530-2533 ; 0167577X (ISSN) Tamjid, E ; Bagheri, R ; Vossoughi, M ; Simchi, A ; Sharif University of Technology
    TiO2 nanostructures with different morphologies (spherical, tube, leaf-like and flower-like particles) were synthesized via a facile hydrothermal process. Polycaprolactone (PCL)/10 vol.% TiO2 nanocomposites were prepared by solvent casting methods. In vitro bioactivity of the nanocomposite films was examined by immersion in the simulated body fluid (SBF) for up to 28 days. It was found that the morphology of titania nanostructures significantly influence the in vitro bioactivity of PCL/TiO 2 nanocomposites. This observation was attributed to the amount of anatase phase and the specific surface area of the TiO2 nanostructures, which provide high surface exposure to SBF  

    Evaluation of ascorbic acid-loaded calcium phosphate bone cements: Physical properties and in vitro release behavior

    , Article Ceramics International ; Vol. 40, issue. 3 , April , 2014 , pp. 3961-3968 ; ISSN: 02728842 Hemmati, K ; Hesaraki, S ; Nemati, A ; Sharif University of Technology
    In this study, different concentrations of ascorbic acid (50, 100 and 200 μg/mL) were added to the liquid phase of a calcium phosphate cement (CPC). The cements were immersed in simulated body fluid (SBF) for different intervals and physical, physicochemical and mechanical properties of them were evaluated. The release of added ascorbic acid from CPCs into the SBF solution was also studied. From the results, both setting time and injectability of CPC decreased by adding ascorbic acid, however the compressive strength was sharply increased before soaking in SBF solution. But, the compressive strength values of all cements (with or without ascorbic acid) soaked in SBF solution for more than 7... 

    Effect of pH and carbon nanotube content on the corrosion behavior of electrophoretically deposited chitosan-hydroxyapatite-carbon nanotube composite coatings

    , Article Ceramics International ; Volume 39, Issue 5 , July , 2013 , Pages 5393-5402 ; 02728842 (ISSN) Batmanghelich, F ; Ghorbani, M ; Sharif University of Technology
    In the first stage, chitosan (CH)-hydroxyapatite (HA)-multiwalled carbon nanotube (MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. In the next stage, effects of pH and MWCNT content of the suspension on the corrosion behavior and deposition mechanism were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves... 

    Synthesis and characterisation of β-tricalcium phosphate coating on zirconia toughened alumina by biomimetic method

    , Article Advances in Applied Ceramics ; Volume 112, Issue 3 , 2013 , Pages 140-145 ; 17436753 (ISSN) Esfahani, H ; Nemati, A ; Salahi, E ; Sharif University of Technology
    The present work studied bioactive coatings on the surface of ceramic biomaterials. Zirconia toughened alumina (ZTA) composites containing 15 mol.-%. Partially stabilised zirconia was prepared after 1 h sintering at 1550°C. Apatite layers were then coated onto the surfaces of composites by the biomimetic method using 1·5-2 multiply concentrations of simulated body fluid (SBF). Before treatment in SBFs, a sodium silicate layer was employed as nucleating agent to induce the formation of a calcium phosphate layer. The effect of immersion time on the morphology of the precipitate was monitored with a scanning electron microscope. X dot maps revealed that there is a relationship between... 

    Development of hydroxyapatite nanorods-polycaprolactone composites and scaffolds derived from a novel in-situ sol-gel process

    , Article Tissue Engineering and Regenerative Medicine ; Volume 9, Issue 6 , 2012 , Pages 295-303 ; 17382696 (ISSN) Rezaei, A ; Mohammadi, M. R ; Sharif University of Technology
    Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which displays splendid biocompatibility and bioactivity properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL) was employed as a matrix and hydroxyapatite nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in-situ sol-gel process using low cost chemicals. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD),... 

    Sol-gel derived hydroxyapatite coating on TiB 2/TiB/Ti substrate

    , Article Surface Engineering ; Volume 28, Issue 7 , August , 2012 , Pages 526-531 ; 02670844 (ISSN) Esfahani, H ; Dabir, F ; Taheri, M ; Sohrabi, N ; Toroghinejad, M. R ; Sharif University of Technology
    The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by... 

    Synthesis and characterization of sol-gel derived hydroxyapatite-bioglass composite nanopowders for biomedical applications

    , Article Journal of Biomimetics, Biomaterials, and Tissue Engineering ; Volume 12, Issue 1 , 2012 , Pages 51-57 ; 16621018 (ISSN) Adibnia, S ; Nemati, A ; Fathi, M. H ; Baghshahi, S ; Sharif University of Technology
    The main purpose of this study is to prepare and characterize hydroxyapatite (HA)-10%wt bioglass (BG) composite nanopowders and its bioactivity. Composites of hydroxyapatite with synthesized bioglass are prepared at various temperatures. Suitable calcination temperature is chosen by evaluating of the phase composition. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) techniques are utilized to characterize the prepared nanopowders. The bioactivity of the prepared composite samples is evaluated in an in vitro study by immersion of samples in simulated body fluid (SBF) for predicted time. Fourier transformed infrared (FTIR) spectroscopy and... 

    Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering

    , Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 301-310 ; 09284931 (ISSN) Mahdieh, Z ; Bagheri, R ; Eslami, M ; Amiri, M ; Shokrgozar, M. A ; Mehrjoo, M ; Sharif University of Technology
    Elsevier Ltd 
    Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples,... 

    Biomimetic apatite layer formation on a novel citrate starch scaffold suitable for bone tissue engineering applications

    , Article Starch/Staerke ; Volume 68, Issue 11-12 , 2016 , Pages 1275-1281 ; 00389056 (ISSN) Nourmohammadi, J ; Shahriarpanah, S ; Asadzadehzanjani, N ; Khaleghpanah, S ; Heidari, S ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    The formation of biomimetic bone-like apatite layers throughout the biopolymer-based hydrogel scaffold is an attractive approach in bone tissue engineering. Here, the starch scaffold was prepared using a combination of particulate leaching and freeze-drying techniques. The fabricated structures were then modified by citric acid to investigate the formation of bone-like apatite layer on the porous citrate-based scaffold after soaking in simulated body fluid (SBF). The Fourier Transform Infrared (FTIR) spectra and X-ray diffraction (XRD) patterns revealed that the B-type carbonated apatite has successfully deposited on the scaffold after immersing in SBF for 28 days. Indeed, high chemical... 

    Characterization of sol-gel derived silver/fluor-hydroxyapatite composite coatings on titanium substrate

    , Article Surface and Coatings Technology ; Volume 352 , 2018 , Pages 522-528 ; 02578972 (ISSN) Batebi, K ; Abbasi Khazaei, B ; Afshar, A ; Sharif University of Technology
    Elsevier B.V  2018
    A composite coating containing silver, fluoride and hydroxyapatite (Ag-FHA) was developed on titanium substrate by sol-gel method. Triethylphosphite, hydrated calcium nitrate, ammonium fluoride and silver nitrate were used respectively, as P, Ca, F and Ag precursors with a Ca:P ratio 1.67 and concentration of silver was 0.3 wt%. Coatings were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic absorption spectrometry (AAS). Potentiodynamic polarization measurements in simulated body fluid proved corrosion protection caused by both Ag-FHA coatings. Antibacterial activity of coatings against... 

    Synthesis of titanium oxide nanotubes and their decoration by MnO nanoparticles for biomedical applications

    , Article Ceramics International ; Volume 45, Issue 15 , 2019 , Pages 19275-19282 ; 02728842 (ISSN) Esmaeilnejad, A ; Mahmoudi, P ; Zamanian, A ; Mozafari, M ; Sharif University of Technology
    Elsevier Ltd  2019
    In this study, apatite formation ability on TiO2 nanotubes (TNTs) synthesized by anodizing process were compared with TNTs decorated by MnO nanoparticles. The MnO nanoparticles used for decoration process were fabricated via thermal decomposition method. At first, it was strived to find the optimal condition of anodizing process and the effect of applied voltages (15 V, 20 V, and 25 V) and process times (15 min, 20 min, and 25 min) on the diameter of the synthesized TNTs was investigated. Results of microscopic characterizations showed that the completely uniform structure of nanotubes with a diameter in the range of about 100–130 nm was achieved after 20 min of anodizing process at an... 

    Improved electrochemical performance of plasma electrolytic oxidation coating on titanium in simulated body fluid

    , Article Journal of Materials Engineering and Performance ; Volume 28, Issue 7 , 2019 , Pages 4120-4127 ; 10599495 (ISSN) Ahmadnia, S ; Aliasghari, S ; Ghorbani, M ; Sharif University of Technology
    Springer New York LLC  2019
    The effect of plasma electrolytic oxidation (PEO) pre-treatments on corrosion behavior of titanium in simulated body fluid (SBF) is investigated. Three pre-treatments are compared, using silicate, calcium phosphate and mixed silicate and calcium phosphate (1:1) electrolytes, respectively. The resultant coatings in different compositions and morphologies were examined by high-resolution field emission scanning electron microscopy equipped with energy-dispersive spectrometer and x-ray diffraction. The PEO-treated specimens revealed distribution of coating species, mainly the titanium-rich inner coating region. However, findings show highly localized variations in composition within their... 

    Synthesis of composite coating containing tio2 and ha nanoparticles on titanium substrate by ac plasma electrolytic oxidation

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 50, Issue 7 , 2019 , Pages 3310-3319 ; 10735623 (ISSN) Soleymani Naeini, M ; Ghorbani, M ; Chambari, E ; Sharif University of Technology
    Springer Boston  2019
    In this study, biocompatible ceramic layers containing TiO2 and hydroxyapatite (HA) nanoparticles (TiO2/HA) were deposited on pure commercial titanium (Grade 2) by using plasma electrolytic oxidation and AC power supply. The coating process was carried out in five different solutions for various times at a current density of 500 mA cm−2. To achieve the optimum conditions for thickness and microstructure, the coating process was conducted in solutions with a 3 g L−1 concentration of HA nanoparticles. FESEM, XRD, and FTIR results showed that HA nanoparticles were successfully incorporated into the pores of the layer. Furthermore, the corrosion behavior of the coating layers in the simulated...