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    Effect of Bioglass Particle Size and Titania Morphology on the Bioactivity and Kinetics of Tissue Growth in Three-Dimensional Poly(ɛ-Caprolactone) Scaffolds with Controlled Pore Structure Produced by 3D-Printing Process

    , Ph.D. Dissertation Sharif University of Technology Tamjid Shabestary, Elnaz (Author) ; Bagheri, Reza (Supervisor) ; Vossoughi, Manouchehr (Supervisor) ; Simchi, Abdolreza (Co-Advisor)
    Polycaprolactone (PCL) scaffolds and its composites containing bioactive glass particles (45S5) and TiO2 nanostructures with pre-defined and controlled external and internal architecture were prepared via an indirect three-dimensional (3D) printing process. The scaffolds had an interconnected structure with macro- (400-500 μm) and micro- (~25 μm) pores. Bioactivity, mechanical behavior and kinetics of tissue growth in 3D scaffolds were studied. The size effect of biogactive glass particles (6 μm, 250 nm, <100 nm) and morphology of titania nanostructures (spherical, tube, leaf-like, and flower-like particles) were elaborated. The biogactive glass particles with different sizes were prepared... 

    Three-Dimensional Polyamide Nanofibrous Scaffolds for Needle Trap Microextraction of Chlorobenzenes from Water Samples and Comparing them with Two-Dimensional Nanofibres

    , M.Sc. Thesis Sharif University of Technology Manshaei, Faranak (Author) ; Bagheri, Habib (Supervisor)
    In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning).... 

    Fabricating Graphene Paper and Determining Its Electrical and Mechanical Properties and Using It for Proliferation and Differentiation of Neural Stem Cells

    , M.Sc. Thesis Sharif University of Technology Akbar Shirazian, Soheil (Author) ; Akhavan, Omid (Supervisor)
    Nowadays, tissue engineering and stem cells-based therapies have outlined a promising prospect in neural networks regeneration. But it usually requires biocompatible and conductive scaffolds for culturing neural stem cells and directing their differentiation toward the neurons. Graphene due to its unique physical and chemical properties has attracted much interest in tissue engineering. For this purpose, in this study biocompatible graphene oxide foams have been used for neural stem cell culturing. For the first time, graphene oxide foam were fabricated by precipitation of chemically exfoliated graphene oxide sheets in an aqueous suspension onto the PET substrate at ~80 oC under UV... 

    Simulation of Flow's Effect on Microfluid Through 3-Dimentional Scaffold in a Bioreactor

    , M.Sc. Thesis Sharif University of Technology Seddiqi, Hadi (Author) ; Bastani, Dariush (Supervisor) ; Amoabediny, Ghassem (Supervisor)
    Tissue engineering aims to produce artificial tissues and organs to treat the damaged part, by implant in body of patients, is an important issue in research and development. In cases that tissue damage is sever or due to genetic defects or congenital disease, tissue in the body are not fully formed, tissue engineering can be used to regenerate, repair or replace organs or tissues. Cell culture on the scaffold and put it in the bioreactor is a critical step in the formation of tissues or organs. Among various bioreactors, perfusion bioreactor due to increase of convection in the structure of cell-scaffold is widely used. Enhancement of convection increases shear stress on the cells that is... 

    Combination of PRP (platelet Rich plasma)with Polymeric Scaffold for Cartilage Regeneration

    , M.Sc. Thesis Sharif University of Technology Rafiei, Mehrnoosh (Author) ; Abdekhodaei, Mohammad Jafar (Supervisor)
    The aim of this study is the fabrication of 3D porous PCL scaffolds contain core-shell fibers for cartilage tissue engineering. The novel fabrication method is co-axial wet electrospinning simultaneously. These tablets like scaffolds have superior porosity and pore sizes for cell culturing and cell-cell interaction as they have good mechanical properties for cartilage tissue engineering in comparison to 2D electrospun scaffolds. The structure of these 3D scaffolds is mimicking the ECM of cartilage. This study presents the coaxial electrospinning of PCL nanofibers encapsulated with bovine serum albumin and platelet rich plasma for demonstration of controlled release and bioactivity retention,... 

    Design and Fabrication of Three Dimensional Scaffold Using Bio-Printing Technique for Cartilage Tissue Engineering

    , M.Sc. Thesis Sharif University of Technology Mohsenifard, Sadaf (Author) ; Mashayekhan, Shohreh (Supervisor) ; Hassanzadeh, Zabiollah (Co-Supervisor)
    Herein, we successfully prepared two types of hydrogels, alginate-beta-cyclodextrin based hydrogel and alginate without beta-cyclodextrin hydrogel in order to use in cartilage tissue engineering. At first, sodium alginate was modified with beta-cyclodextrin ring due to incorporate the kartogenin (KGN) differentiating drug in the hydrogel structure. For confirming the correctness of the modification reactions, H-NMR spectroscopy was used. In the presence of phenolized-ECM, alginic acid, modified alginate with beta cyclodextrin, HRP, H2O2, calcium carbonate, and glucono-delta-lactone (GDL), ECM-alginate-IPN and ECM-modified-alginate-IPN hydrogels were synthesized. Then, the KGN was loaded on... 

    Rolled graphene oxide foams as three-dimensional scaffolds for growth of neural fibers using electrical stimulation of stem cells

    , Article Carbon ; Volume 97 , 2016 , Pages 71-77 ; 00086223 (ISSN) Akhavan, O ; Ghaderi, E ; Shirazian, S. A ; Rahighi, R ; Sharif University of Technology
    Elsevier Ltd 
    Graphene oxide foam (GOF) layers with thicknesses of ∼15-50 μm and density of ∼10 graphene oxide (GO) sheets/μm were fabricated by precipitation of chemically exfoliated GO sheets in an aqueous suspension at ∼80 °C under UV irradiation. Then, rolled GOFs with desirable scales were developed as electrically conductive 3D-scaffolds and applied in directional growth of neural fibers, through differentiation of human neural stem cells (hNSCs) into neurons under an electrical stimulation. X-ray photoelectron spectroscopy indicated that the UV irradiation resulted in partial deoxygenation of the layers. Scanning electron microscopy and Raman spectroscopy confirmed the presence of multilayer GO... 

    Interface engineering of perovskite solar cell using a reduced-graphene scaffold

    , Article Journal of Physical Chemistry C ; Volume 120, Issue 35 , Volume 120, Issue 35 , 2016 , Pages 19531-19536 ; 19327447 (ISSN) Tavakoli, M. M ; Tavakoli, R ; Hasanzadeh, S ; Mirfasih, M. H ; Sharif University of Technology
    American Chemical Society 
    Interface engineering of solar cell device is a prominent strategy to improve the device performance. Herein, we synthesize reduced-graphene scaffold (rGS) by using a new and simple chemical approach. In this regard, we synthesize a hollow structure of graphene and then fabricate a three-dimensional scaffold of graphene with a superior surface area using electrophoretic process. We employ this scaffold as an interface layer between the electron transfer and absorber layers in perovskite solar cell. The characterization tests and photovoltaic results show that rGS improves the carrier transportation, yielding a 27% improvement in device performance as compared to conventional device. Finally,... 

    Investigation and Determination of Optimal Composition of Hydrogels and Nanoparticles for Proliferation of Mesenchymal Stem Cells in Alginate Beads

    , M.Sc. Thesis Sharif University of Technology Akbari Kenari, Mahsa (Author) ; Yaghmaei, Soheila (Supervisor) ; Arpanaei, Ayyoob (Supervisor)
    The aim of this dissertation is to investigate and determine the optimal composition of hydrogels that can meet the needs of stem cells for the growth and proliferation of mesenchymal stem cells. In this research, firstly, unfunctionalized and functionalized mesoporous silica nanoparticles (with an average diameter of approximately 90 nm), were synthesized. Scanning electron microscopy and zeta potential measurement were utilized to study their morphology and surface charge. Then, graphene oxide nanosheets were synthesized. Field emission electron microscopy, zeta potential measurement and Fourier transform infrared spectrum analysis were used to examine their morphology, surface charge and... 

    Mechanical modeling of silk fibroin/TiO2 and silk fibroin/fluoridated TiO2 nanocomposite scaffolds for bone tissue engineering

    , Article Iranian Polymer Journal (English Edition) ; Volume 29, Issue 3 , February , 2020 , Pages 219-224 Johari, N ; Madaah Hosseini, H. R ; Samadikuchaksaraei, A ; Sharif University of Technology
    Springer  2020
    Biocompatible and biodegradable three-dimensional scaffolds are commonly porous which serve to provide suitable microenvironments for mechanical supporting and optimal cell growth. Silk fibroin (SF) is a natural and biomedical polymer with appropriate and improvable mechanical properties. Making a composite with a bioceramicas reinforcement is a general strategy to prepare a scaffold for hard tissue engineering applications. In the present study, SF was separately combined with titanium dioxide (TiO2) and fluoridated titanium dioxide nanoparticles (TiO2-F) as bioceramic reinforcements for bone tissue engineering purposes. At the first step, SF was extracted from Bombyx mori cocoons. Then,... 

    Manipulating failure mechanism of rapid prototyped scaffolds by changing nodal connectivity and geometry of the pores

    , Article Journal of Biomechanics ; Volume 45, Issue 16 , 2012 , Pages 2866-2875 ; 00219290 (ISSN) Amirkhani, S ; Bagheri, R ; Zehtab Yazdi, A ; Sharif University of Technology
    The performance of cellular solids in biomedical applications relies strongly on a detailed understanding of the effects of pore topology on mechanical properties. This study aims at characterizing the failure mechanism of scaffolds based on nodal connectivity (number of struts that meet in joints) and geometry of the pores. Plastic models of scaffolds having the same relative density but different cubic and trigonal unit cells were designed and then fabricated via three dimensional (3-D) printing. Unit cells were repeated in different arrangements in 3-D space. An in-situ imaging technique was utilized to study the progressive deformation of the scaffold models. Different nodal...