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Modeling of the Mechanical Behavior of Rapid Prototyped Scaffolds Based on Their Pore Architecture and Introducing a Prototyping Method to Produce Ceramic Scaffolds
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Baghaban Eslaminejad, Mohamad Reza (Supervisor)
Abstract
Mechanical behavior of tissue engineering scaffolds plays a key role in their biological performance; however the effect of microstructural features on mechanical behavior of such scaffolds is still under investigation. The objective of this study was to investigate the influence of pore architecture and relative density on mechanical behavior of rapid prototyped scaffolds. In this regard, scaffolds with different cubic, hexagonal and trigonal unit cells were designed. These unit cells were repeated in different arrangements in 3D space to produce different nodal connectivities. The internal dimension of pores varied from 500 to 600 μm. Plastic models of scaffolds then fabricated by 3D...
Investigating the Optimum Conditions for Cell Growth and Behavior on Hydrogel Surfaces
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohre (Supervisor) ; Maghsudi, Vida (Supervisor)
Abstract
Generally, the concept of producing ‘spare parts’ of the body for replacement of damaged or lost organs lies at the core of the varied biotechnological practices referred as tissue engineering. Tissue engineering is an interdisciplinary field that incorporates principles of engineering with the life sciences. Tissue engineering is based on three principle; cells, scaffolds for cells expansion, attachment as an environment like ECM and growth factors. These things together can help tissue engineers to provide microenvironments which are suitable for special cells. The most important thing in this kind of works is the ability to simulate environment for cells the same as body. According to the...
Simulation of Mass Transfer in Cartilage Regeneration
, M.Sc. Thesis Sharif University of Technology ; Abd Khodaei, Mohammad Jafar (Supervisor)
Abstract
The in vivo cell culture process as the main part of tissue engineering was investigated through mathematical modelling and computational fluid dynamic (CFD) simulation of cartilage cell growth. Simulations can provideprocess insights for defining the optimum conditions in order to reach higher culture efficiency. In the mathematical modelling of the cell growth, it was intended to consider the most influencing factors such as biomass concentration, volume fraction, glucose concentration and shear stress levels. These results can be obtained mathematically by solving a set of partial differential equations coupling the glucose concentration, the velocity field and cell growth with each other....
Design and Fabrication of Conductive Polymeric Nanocomposite Scaffolds for Nerve Tissue Engineering
, Ph.D. Dissertation Sharif University of Technology ; Ramezani Saadat, Ahmad (Supervisor)
Abstract
In the current study, design, fabrication, and characterization of a novel conductive nanocomposite scaffold for nerve tissue engineering applications is reported. For this purpose, the highly conductive polyaniline/graphene nanocomposite (PAG) was synthesized via emulsion polymerization, used for fabrication of conductive chitosan/gelatin/PAG scaffolds, and the effect of PAG amount on the various properties of scaffolds were investigated. The synthesized graphene, polyaniline, and PAG were characterized and the obtained results revealed that partially exfoliated graphene nanosheets and highly conductive PAG with a conductivity of about 12 S.cm-1 and 7 S.cm-1, respectively were obtained. The...
Preparation of Gelatin-Alginate Hydrogel for Using as Cell Culture Scaffold
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Maghsoudi, Vida (Supervisor)
Abstract
Hydrogels are polymeric three-dimensional networks able to swell in the presence of an aqueous medium. Hydrogels from natural proteins and polysaccharides are ideal scaffolds for tissue engineering since they resemble the extracellular matrices of tissue comprised of various amino acids and sugar-based macromolecules.The biocompatible and biodegradable hydrogel scaffolds are promising materials for tissue engineering. Here, we report a new class of hydrogels derived from oxidized alginate (OA) and gelatin. The prepared oxidized alginate was shown to be efficient in crosslinking gelatin, leading to hydrogel formation. The effect of degree of oxidation and concentration of OA on the mechanical...
Study & Synthesis of Biocompatible Scaffolds for Animal Cell Cultures
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Co-Advisor) ; Pajoum Shariati, Ramin (Co-Advisor)
Abstract
Natural tissues of body consist of Extra Cellular Matrix (ECM) and cells. Scaffold produces a temporary matrix for cells and facilitates oxygen and nutrients transport which enhances tissue regeneration. Therefore, attempts in regeneration of tissues and organs by scaffolds attracted great interest in today’s researchs. Choosing scaffold fabrication method and its polymer type, play a key role in scaffold specifications as they determine scaffold properties. In this project electrospinning was chosen as the scaffold fabrication method which is because of the unique properties of scaffolds fabricated by this method and also its ability in producing micro and nano fibers. At first set of...
Chitosan/Gelatin/Mg Substituted Hydroxyapatite Nano Composite Scaffold for Bone Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor) ; Fathi, Mohammad Hossein (Co-Advisor)
Abstract
The present study is work on fabrication and characterization of a chitosan/ gelatin/ Mg substituted hydroxyapatite nano composite scaffold for bone tissue engineering. At the first step pure and Mg-substituted hydroxyapatite (HA) (Ca10-xMgx(PO4) 6OH2) nano-hexagonal rods with 14–45 nmdiameter.for this, calcium nitrate, magnesium phosphate hydrate and potassium dihydrogenphosphate were used as precursors for Ca, Mg, and P, respectively. Calculated amounts of magnesium ions (Mg+2) especially from 0 to 8% (molar ratio) were incorporated as substituted into the calcium sol solution. Deionized water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH= 9....
Fabrication of Artificial skin with Electrospun of Nanofiber made of PCL and PVA
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Naghdabadi, Reza (Co-Advisor) ; Vosooghi, Manoochehr (Co-Advisor) ; Firoozbakhsh, Keikhosro (Co-Advisor)
Abstract
The main goal of this project is to fabricate the scaffolds including Polycaprolactone and Polyvinyle alcohol nanofibers in order to use as artificial skin. For this purpose, electrospinning parameters have been optimized for various injection rates and the scaffolds containing different percent of PCL and PVA have been made. By investigating the cell growth on these scaffolds, the one made up PVA/PCL (30% ) has been introduced as the best scaffold. To improve biological properties of chosen scaffold, a layer of collagen was coated. The angiogenesis capacity has been improved by adding Heparin to PVA nanofibers. Based on assay of heparin release, it was shown that Heparin is released within...
Experimental Study of Biocompatibility and Proliferation of Stem Cells on the Scaffold with Natural Structure
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Supervisor) ; Haghighipour, Nooshin (Supervisor)
Abstract
The heart diseases and in particular coronary artery disease have been vastly increased in recent years. Bypass operation is the major recognized way of this disease treatment however, one third of patients don’t have the suitable autologous vein for this operation. It should be noted that for this operation a suitable conduit with diameter as narrow as possible is needed. On the other hand, usage of synthetic polymers won’t be suitable for this operation due to the coagulation forming. The only way to overcome this problem is the use of tissue engineering with the aid of scaffold and autologous cells with the natural tissue function, which reconstructed the desire tissue causing no...
Sol-Gel Preparation and Study of Bio-Composite Scaffold Containing Chitosan-Gelatin/ Nano-Hydroxyapatite for Bone Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
In present work, hydroxyapatite nano-rods are synthesized using a simple sol-gel method with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors respectively and ammonia was used for adjusting the pH=9. To obtain rod shape hydroxyapaite powder, multi wall carbon nanotubes were added to the solution, nHA powder was calcinated at 60 and 450 ℃. In second step, chitosan-gelatin/nanoHA solution were prepared by blending chitosan and gelatin in different concentrations with nanoHA powder, then the solution was freeze dried to maintain a composite scaffold. The prepared HA powder and bio-composite scaffold were characterized by X-ray diffraction (XRD), field...
Hydrodynamic Simulation of Vascular Scaffolds
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Mashayekhan, Shohreh (Supervisor)
Abstract
This research studies a 3D channeled myocardium scaffold with computational fluid dynamics. It proposes a mathematical model to evaluate the impact of oxygen carriers and scaffold geometry on cell growth in a 3D cardiac construct. The modeling results show that using 5.4% perfluorocarbon oxygen carrier (PFC) has increased cardiac cells density 15% of the initial seeded cells comparing to pure culture medium without PFC supplementation. Effects of the scaffold geometry on cell density in the construct were examined by increasing channel numbers and changing the construct length. The results show that increasing channel numbers (by 50% decreasing channels diameter and wall to wall spacing) the...
Development of an Optimized Skin Scaffold Capable of Growth Factor Release for Acute Skin Wound Healing
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Firoozbakhsh, Keykhosrow (Supervisor)
Abstract
As the first barrier in front of external damages, skin is prone to the largest number of damages applied to one’s body. Acute wounds are considerably prevalent world-widely, imposing very high costs to governments. The purpose of the current project, is to propose a novel skin scaffold capable of growth factor delivery for enhancing the wound healing process in acute wounds. Such a scaffold should be able to decrease the required time for healing process, also to improve the quality of the regenerated skin compared to available commercial products. Furthermore, it should be highly biocompatible, biodegradable, and non-toxic. In this project, to manufacture the artificial skin scaffold, a...
Design and Fabrication of Engineered Biomaterials for Tissue Engineering Applications such as Cardiovascular System
, M.Sc. Thesis Sharif University of Technology ; Shamlou, Amir (Supervisor)
Abstract
Cardiovascular diseases are the leading cause of death all over the world, even more common than cancers. The first reason of mortality in Iran according to statistics is the occlusion of coronary arteries. Unfortunately almost one third of patients doesn’t have enough blood vessels to be used in the bypass surgery and need artificial vessels. These artificial blood vessels with small diameters (less than 6 mm) will fail quickly. As a result there is an increasing demand for tissue engineered blood vessels which are capable of enduring high blood pressures. An artificial blood vessel should mimic both structure and mechanical properties of the real one. Blood vessels have layered structures,...
Experimental Study of Using Cellulosic Compounds in Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Manouchehr (Supervisor) ; Karimi, Afzal (Supervisor) ; Faghihi, Faezeh (Co-Supervisor)
Abstract
Fabrication and characterization of different surface charged cellulose electrospun scaffolds including cellulose acetate, cellulose, carboxymethyl cellulose and quaternary ammonium cationic cellulose for biomedical applications have been reported in this research. We describe preparation of cellulosic nanofibers through the electrospinning following deacetylation cellulose acetate. Moreover, surface modification of electrospun cellulose nanofibers is carried out to obtain carboxymethyl cellulose and quaternized cellulose nanofibers, respectively. At last, the structural, morphological, mechanical, swelling, wettability and the cell culture properties of the scaffolds were analyzed and...
Preparation and Characterization of Hydroxyapatite Nanostructures Using Natural Resources for Bone Scaffold Applications
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor) ; Askari, Masoud (Supervisor)
Abstract
This investigation presents synthesis and characterization of pure and monophasic hydroxyapatite (Ca10(PO4)6(OH)2; HA) Nanostructures prepared by coral and oyster shell powders heated at 800 oC for 8 h as precursor via precipitation method. The morphology of HA nanostructures was controlled in the presence of various surfactants such as SDS, CTAB and PVP. The HA Nanorods synthesized by SDS were applied to fabricate bone scaffolds. Particle sizes of the HA Nanoparticles were about 20-30 nm. Pours three-dimensional HA/Ge/CMC scaffolds cross-linked by citric and oxalic acids were synthesized. In order to increase the pore size of the scaffolds, NaCl with medium (180-250 µm) and large (420-500...
Fabrication of Nano Structure Tialite-fibroin Scaffold
, M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza (Supervisor)
Abstract
The development of novel three dimensional degradable porous scaffolds is of great interest for tissue engineering.silk ibroin has recently received intensive attention as a material for use in fabrication of 3D porous scaffolds beacuse of its excellent biocompatibility, physical and mechanical properties, and easy processibility. However, silk alone has no osteoinductive property and considerebely lower mechanical properties than native bone. In order to overcome this limitation silk fibroin can be combined with other materials.the properties of scaffold can be significantly improved and new features can be endowed by the second ccomposition. The present study deals with fabrication of...
Formulation and Properties of Scaffolds based on Hydroxyapatite Composites Containing Titanium Dioxide and Magnesium Oxide
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor)
Abstract
This study investigates the effect of titanium dioxide and magnesium oxide additives on hydroxyapatite synthesized by sol-gel and composite with the predominant phase of hydroxyapatite by in situ method to improve mechanical properties. Scaffold samples were synthesized with nanometer-sized hydroxyapatite and composite powder particles by gel casting and sintered at 1200 ° C. Then, to evaluate the synthesized powders, simultaneous thermal analysis (STA), X-ray diffraction test, FTIR test, FESEM, EDS, and MAP analysis were used. Also, to evaluate the mechanical properties of the scaffolds, a compressive test was used, and to evaluate the scaffolds' density, the Archimedes method was used....
Modeling and Analysis of Interaction between Tairlored CNT-Graphene Scaffolds and Stem Cell Growth and Differentitation
, Ph.D. Dissertation Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Kheikhosrow (Co-Supervisor)
Abstract
Since its successful synthesis as single layer during the past decades, Graphene and its derivatives have been extensively employed by many researchers in various science and engineering fields. The studies to characterize and define graphene behaviour are still in demand to answer the questions around these structures. The unique feathures of graphene such as high strength, good conductivity, large available surface, intoxicity and biocompatibility, has made it a suitable candidate to used in novel structures and materials. In this work, hybrid structures made from graphene and carbon nanotubes are investigated which can be utilized as scaffolds in tissue engineering.After an introduction...
Fabrication of Micron Resolution Polymer Structures with Electrohydrodynamic Printing
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mohammad Reza (Supervisor)
Abstract
In recent years, additive manufacturing has been widely used in prototyping and production of industrial-commercial pieces. Additive manufacturing or three-dimensional (3D) printing is able to easily produce any piece for initial prototyping, no matter how complex it is. The fused deposition modeling (FDM) is a type of additive manufacturing process that produces the piece with the mechanism of feeding the PLA filament, then the molten polymer extrusion and depositing the fluid layer by layer with a high viscosity. Since the thickness of the layers is directly proportional to the diameter of the nozzle and the diameter of the used nozzles cannot be in the micron range (lower than 100...
Investigation of The Effect Of Microgravity On Bone Marrow Stromal Cell Growth And Infiltration On An Optimized 3d Structured Scaffold
,
M.Sc. Thesis
Sharif University of Technology
;
Yaghmaei, Soheila
(Supervisor)
;
Vossoughi, Manouchehr
(Supervisor)
;
Haji Ebrahimi, Zahra
(Supervisor)
;
Janmaleki, Mohsen
(Co-Supervisor)
Abstract
To develop a novel cell culture method for enhancement of bone marrow stromal cell growth and infiltration into the 3d electrospun PCL-based scaffold, we utilized the RPM system to simulate microgravity. In current study, six different scaffolds are produced using the electrospinningelectrospraying technique. These scaffolds are compared based on their structural (average diameter and SEM micrographs), mechanical (Tensile strength, elongation and wettability) and biological (Biodegradability, bioactivity, biocompatibility, cell adhesion, cell infiltration and antibacterial quality) characteristics. It is noted that the porous nano-hydroxyapatite/titanium hydroxide/polycaprolactone...