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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) ; Afshar, A ; Chen, J ; Zhang, X ; Sharif University of Technology
Elsevier Ltd
2007
Abstract
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 ; Bagheri, Reza (Supervisor)
Abstract
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 ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
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 ; Afshar, Abdollah (Supervisor)
Abstract
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 ; Ekrami, Ali Akbar (Supervisor) ; Ziaei Moayyed, Ali Akbar (Supervisor)
Abstract
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...
A novel approach for compensating the significance of tubule's architecture in urine concentrating mechanism of renal medulla
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 B , 2013 ; 9780791856222 (ISBN) ; Mehr, S. M. N ; Falsafi, P ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2013
Abstract
Many theories and mathematical simulations have been proposed concerning urine concentrating mechanism (UCM). The WKM and region approach are the two most valuable methods for compensating the effect of tubule's architecture in renal medulla. They both have tried to simulate tubule's confinement within a particular region mathematically in one spatial dimension. In this study, continuity, momentum and species transport equations along with standard expressions for transtubular solutes and water transports on tubule's membrane were solved numerically in three spatial dimensions which practically is the main significance of our novel approach. Model structure has been chosen as simple as...
Dose-dependent effects of nanoscale graphene oxide on reproduction capability of mammals
, Article Carbon ; Volume 95 , December , 2015 , Pages 309-317 ; 00086223 (ISSN) ; Ghaderi, E ; Hashemi, E ; Akbari, E ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and...
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) ; Behnamghader, A ; Afshar, A ; Ardeshir, M ; Forati, T ; Sharif University of Technology
2007
Abstract
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...
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) ; Aliasghari, S ; Ghorbani, M ; Sharif University of Technology
Springer New York LLC
2019
Abstract
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...
Microstructural evolution, mechanical properties, and corrosion resistance of a heat-treated Mg alloy for the bio-medical application
, Article Journal of Magnesium and Alloys ; Volume 7, Issue 1 , 2019 , Pages 80-89 ; 22139567 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Sharif University of Technology
National Engg. Reaserch Center for Magnesium Alloys
2019
Abstract
During the recent years, some Mg based alloys have extensively been considered as a new generation of degradable and absorbable bio-medical materials. In this work, the Mg–2Zn–1Gd–1Ca (wt%) alloy as a new metallic bio-material was produced by the casting process followed by the heat treatment. The samples of the alloy were solution treated at temperatures of 500, 550, and 600 °C and then quench aged at temperatures of 125, 150, and 175 °C. The results of SEM-EDS examinations indicated that the alloy microstructure consists of α-Mg matrix and the Ca2Mg6Zn3 and Mg3Gd2Zn3 secondary phases. With regard to the results of Vickers hardness test, the temperatures of 500 °C and 150 °C were selected...
The fabrication and characterization of bioactive Akermanite/Octacalcium phosphate glass-ceramic scaffolds produced via PDC method
, Article Ceramics International ; 2020 ; Paryab, A ; Khalilifard, R ; Anousheh, M ; Malek Khachatourian, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase....
Effects of Sr and Mg dopants on biological and mechanical properties of SiO2–CaO–P2O5 bioactive glass
, Article Ceramics International ; Volume 46, Issue 14 , 2020 , Pages 22674-22682 ; Moradi, M ; Abouchenari, A ; Pakseresht, A.H ; Esmaeilkhanian, A ; Shokouhimehr, M ; Shahedi Asl, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the present study, the effects of Sr and Mg were investigated on mechanical and biological properties of 58S bioactive glass (BG). SiO2-P2O5-CaO BG with different contents of Sr and Mg were synthesized via the sol-gel method and immersed in simulated body fluid (SBF) for several days to explore their biocompatibility. Precise analyses of the BG using X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy showed that the Mg-doped BG containing 8 wt % MgO possessed better biocompatibility. It was also found that mechanical properties of the BG could be improved by increasing the amounts of MgO and SrO. Both 5Sr-BG and 8Mg-BG samples did not exhibit any...
In vitro dissolution of plasma-sprayed hydroxyapatite coatings with different characteristics: Experimental study and modeling
, Article Biomedical Materials ; Volume 3, Issue 1 , 2008 ; 17486041 (ISSN) ; Ziaei Moayyed, A. A ; Sheikh Mehdi Mesgar, A ; Sharif University of Technology
2008
Abstract
The dissolution of plasma-sprayed hydroxyapatite (PHA) coatings with different characteristics, produced by various spraying conditions, in a Tris-buffered solution at pH 7.4 was experimentally studied through the measurement of the release of calcium ions. The phase composition of the coatings at surface and interface, and the porosity were evaluated. The analytical modeling revealed that the calcium dissolution process was composed of two stages. The first stage was found to be both surface and diffusion controlled. The second stage was an exactly diffusion-controlled dissolution. In the first stage, the rate of dissolution and the solubility of the coatings with minimum contents of...
The fabrication and characterization of bioactive Akermanite/Octacalcium phosphate glass-ceramic scaffolds produced via PDC method
, Article Ceramics International ; Volume 47, Issue 5 , 2021 , Pages 6653-6662 ; 02728842 (ISSN) ; Paryab, A ; Khalilifard, R ; Anousheh, M ; Malek Khachatourian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase....
The fabrication and characterization of bioactive Akermanite/Octacalcium phosphate glass-ceramic scaffolds produced via PDC method
, Article Ceramics International ; Volume 47, Issue 5 , 2021 , Pages 6653-6662 ; 02728842 (ISSN) ; Paryab, A ; Khalilifard, R ; Anousheh, M ; Malek Khachatourian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase....
Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid
, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 32, Issue 7 , 2022 , Pages 2216-2228 ; 10036326 (ISSN) ; Jafari, H ; Pishbin, F ; Mohammadi, R ; Simchi, A ; Sharif University of Technology
Nonferrous Metals Society of China
2022
Abstract
The biodegradation behavior of Mg, coated by polymethyl methacrylate as well as polymethyl methacrylate (PMMA)−bioactive glass (BG) composite was investigated. Electrophoretic deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical materials. The deposited coatings were characterized using SEM, EDS, FTIR, and water contact angle measurements. Biodegradation behavior study of the coated Mg was performed using linear polarization, impedance spectroscopy, and immersion tests in simulated body fluid. The compact and homogeneous composite coating was developed as evidenced by electron microscopy results....
Cytotoxicity of protein corona-graphene oxide nanoribbons on human epithelial cells
, Article Applied Surface Science ; Volume 320 , 30 November , 2014 , Pages 596-601 ; ISSN: 01694332 ; Akhavan, O ; Javanbakht, T ; Mahmoudi, M ; Yahia, L ; Sharif University of Technology
Abstract
Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell...
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) ; Nemati, A ; Sadeghian, Z ; Sharif University of Technology
2013
Abstract
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...
Relationship between serum level of selenium and metabolites using 1hnmr-based metabonomics in parkinson's disease
, Article Applied Magnetic Resonance ; Volume 44, Issue 6 , January , 2013 , Pages 721-734 ; 09379347 (ISSN) ; Kyani, A ; Darvizeh, F ; Mehrpour, M ; Tafazzoli, M ; Shahidi, G ; Sharif University of Technology
2013
Abstract
Parkinson's disease (PD) is a neurodegenerative disease, which is not easily diagnosed using clinical tests and the discovery of proper methods would be a major step towards a successful diagnosis. In the present study, we employed metabolic profiling using proton nuclear magnetic resonance spectroscopy to find metabolites in serum, which are helpful for the diagnosis of PD. Classification of PD and healthy subject was done using random forest. Serum levels of selenium measured by atomic absorption spectrometry in PD group were lower than the serum selenium levels in the control group. The metabolites causing selenium changes in PD patients were identified using random forest, and a model...
Preparation of a naltrexone HCL potentiometric sensor and its application to pharmaceutical analysis and drug determination in biological fluids
, Article Journal of Food and Drug Analysis ; Volume 19, Issue 4 , 2011 , Pages 445-451+539 ; 10219498 (ISSN) ; Shahrokhian, S ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
Abstract
A novel ion selective electrode is fabricated for naltrexone HCl and used in pharmaceutical analysis and drug determination in biological fluids without complicated pretreatments and extractions, using direct potentiometry. The naltrexone complex with sodium tetraphenyl borate (NaTPB) is obtained by in situ soaking PVC membrane electrode in an 1 × 10 -3 M naltrexone solution. The sensor exhibited fast, reproducible and linear sub-Nernstian response over concentration range of 1 × 10 -5 - 1 × 10 -3 M with a detection limit of 5 × 10 -6 M. The membrane sensor was successfully applied to the determination of naltrexone in capsules as well as for its determination in urine and plasma samples