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    A model for cell density effect on stress fiber alignment and collective directional migration

    , Article Physical Biology ; Volume 12, Issue 6 , 2015 ; 14783967 (ISSN) Abeddoust, M ; Shamloo, A ; Sharif University of Technology
    2015
    Abstract
    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes - including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements - are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during... 

    Modified antisolvent method for improving the performance and stability of triple-cation perovskite solar cells

    , Article ACS Omega ; Volume 6, Issue 1 , 2021 , Pages 172-179 ; 24701343 (ISSN) Samadpour, M ; Golchini, A ; Abdizadeh, K ; Heydari, M ; Forouzandeh, M ; Saki, Z ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society  2021
    Abstract
    Antisolvent crystallization is known as an effective approach for the deposition of pinhole-free solution-processed perovskite layers for high-performance solar cells. Here, we introduce a modified antisolvent dripping method by adding tetra ethyl orthosilicate (TEOS) into chlorobenzene as a conventional antisolvent. Through TEOS modification, perovskite solar cells show efficiencies as high as 16% with more than 85% retention after 290 h storage at ambient conditions in comparison to 20% in pristine cells. This significant enhancement in efficiency and stability mainly related to the decrement of the density of surface defects, which is confirmed by considerably enhanced photoluminescence... 

    Development of a virtual cell model to predict cell response to substrate topography

    , Article ACS Nano ; Volume 11, Issue 9 , 2017 , Pages 9084-9092 ; 19360851 (ISSN) Heydari, T ; Heidari, M ; Mashinchian, O ; Wojcik, M ; Xu, K ; Dalby, M. J ; Mahmoudi, M ; Ejtehadi, M. R ; Sharif University of Technology
    Abstract
    Cells can sense and respond to changes in the topographical, chemical, and mechanical information in their environment. Engineered substrates are increasingly being developed that exploit these physical attributes to direct cell responses (most notably mesenchymal stem cells) and therefore control cell behavior toward desired applications. However, there are very few methods available for robust and accurate modeling that can predict cell behavior prior to experimental evaluations, and this typically means that many cell test iterations are needed to identify best material features. Here, we developed a unifying computational framework to create a multicomponent cell model, called the... 

    Investigation of the minimum miscibility pressure for injection of two different gases into two Iranian oil reservoirs: experimental and theory

    , Article Canadian Journal of Chemical Engineering ; Volume 95, Issue 5 , 2017 , Pages 1014-1020 ; 00084034 (ISSN) Moosazadeh, M ; Keshavarzi, B ; Ghotbi, C ; Sharif University of Technology
    Wiley-Liss Inc  2017
    Abstract
    The results of the minimum miscibility pressure (MMP) determination for miscible injection of CO2 and an associated gas of one of Iranian gas reservoirs into two different oil samples using a slim tube device are presented. For an effective determination of the MMP cell-to-cell slim tube simulation was performed for each case before performing the slim tube experiment and the results were used to determine the pressure intervals in the slim tube experiment. A comparison between the measured MMP values from the slim tube experiments and those calculated by cell-to-cell simulation revealed that the cell-to-cell simulation can be a substitute to slim tube test in cases where time is a primary... 

    Measuring viscoelastic properties of Red Blood Cell using optical tweezers

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 1 , 2019 , Pages 101-108 ; 16826957 (ISSN) Seyed Reihani, S. N ; Azadbakht, A ; Mirzahossein, E ; Mottaghian, M ; Babaei, M ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Efforts have been made to study the behavior of complex materials in micrometer dimensions with various techniques. One of these methods is the use of optical tweezers for biophysical applications. Red blood cells, as the most abundant blood-forming cells, play an important role in the life of living organisms, and their unique mechanical properties are important. In this report, the study of soft materials is done using light tweezers. This work investigates micrometer particle movements in the optical trap and also, when they are connected to a red blood cell. The tweezers allow the Newtonian fluid viscosity, such as water and glycerin, to measure the mechanical properties of viscoelastic... 

    Measuring viscoelastic properties of Red Blood Cell using optical tweezers

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 1 , 2019 , Pages 101-108 ; 16826957 (ISSN) Seyed Reihani, S. N ; Azadbakht, A ; Mirzahossein, E ; Mottaghian, M ; Babaei, M ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Efforts have been made to study the behavior of complex materials in micrometer dimensions with various techniques. One of these methods is the use of optical tweezers for biophysical applications. Red blood cells, as the most abundant blood-forming cells, play an important role in the life of living organisms, and their unique mechanical properties are important. In this report, the study of soft materials is done using light tweezers. This work investigates micrometer particle movements in the optical trap and also, when they are connected to a red blood cell. The tweezers allow the Newtonian fluid viscosity, such as water and glycerin, to measure the mechanical properties of viscoelastic... 

    Human Cells Separation Via Imprinted Polymer

    , M.Sc. Thesis Sharif University of Technology Sabaghi, Davood (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor)
    Abstract
    The goal of this research is to elucidate the mechanism of Cell recognition in molecularly imprinted polymers (MIPs) using already utilized techniques. Our approach employs a more flexible non-covalent imprinting method which starts from a readily available polymer and utilizes an aqueous environment for both MIP synthesis and testing. Cell MIPs against MG-63 cell were synthesized. The synthesis procedure was optimized to obtain better binding characteristics to the targeted cell. Adsorption of target cell onto imprinted Alginate Spheres was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations The imprinted Spheres showed high selectivity toward... 

    Study of electrical conductivity of different water liquids and electrolytes

    , Article Australian Journal of Basic and Applied Sciences ; Volume 4, Issue 8 , 2010 , Pages 3985-3997 ; 19918178 (ISSN) Golnabi, H ; Sharifian, M ; Sharif University of Technology
    2010
    Abstract
    In this study electrical conductivities of pure, distilled, municipal, industrial and river water liquids along with those of different electrolyte solutions are computed at room temperature (25 °C) and compared with the experimental results. For experiment, using a measuring module both R and C value of the water samples are measured by using two different cylindrical cells. The obtained RC product for the long and short cell probes are compared for different water samples. Obtained results give the relaxation time, which is the measure of the conduction relaxation and for a good conducting medium such a time is very short. The relaxation time for the salt solution is about 0.07044 ms... 

    Construction of perovskite solar cells using inorganic hole-extracting components

    , Article ACS Omega ; Volume 3, Issue 1 , 4 January , 2018 , Pages 46-54 ; 24701343 (ISSN) Nouri, E ; Mohammadi, M. R ; Lianos, P ; Sharif University of Technology
    American Chemical Society  2018
    Abstract
    A NiOx−graphene oxide (NiOx−GO) hybrid has been prepared by a simple solution-processed method and was used as hole-extraction material in perovskite solar cells with either gold or carbon as back contact electrode. The impact of GO content on the optoelectronic behavior of NiOx and the photovoltaic performance of the fabricated devices has been studied. Thus, GO incorporation showed a significant improvement in the performance of NiOx-based devices. The best attained efficiency was 13.3%, and it was 45% higher than that with pure NiOx. This is attributed to a significant improvement in the hole extraction, recombination resistance, and energy-level matching in comparison to pure NiOx. In... 

    Improvement of the photovoltaic parameters of perovskite solar cells using a reduced-graphene-oxide-modified titania layer and soluble copper phthalocyanine as a hole transporter

    , Article Physical Chemistry Chemical Physics ; Volume 20, Issue 4 , 2018 , Pages 2388-2395 ; 14639076 (ISSN) Nouri, E ; Mohammadi, M. R ; Xu, Z. X ; Dracopoulos, V ; Lianos, P ; Sharif University of Technology
    Royal Society of Chemistry  2018
    Abstract
    Functional perovskite solar cells can be made by using a simple, inexpensive and stable soluble tetra-n-butyl-substituted copper phthalocyanine (CuBuPc) as a hole transporter. In the present study, TiO2/reduced graphene oxide (T/RGO) hybrids were synthesized via an in situ solvothermal process and used as electron acceptor/transport mediators in mesoscopic perovskite solar cells based on soluble CuBuPc as a hole transporter and on graphene oxide (GO) as a buffer layer. The impact of the RGO content on the optoelectronic properties of T/RGO hybrids and on the solar cell performance was studied, suggesting improved electron transport characteristics and photovoltaic parameters. An enhanced... 

    Reducing surface recombination by a poly(4-vinylpyridine) interlayer in perovskite solar cells with high open-circuit voltage and efficiency

    , Article ACS Omega ; Volume 3, Issue 5 , 2018 , Pages 5038-5043 ; 24701343 (ISSN) Yavari, M ; Mazloum Ardakani, M ; Gholipour, S ; Tavakoli, M. M ; Taghavinia, N ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
    American Chemical Society  2018
    Abstract
    Identifying and reducing the dominant recombination processes in perovskite solar cells is one of the major challenges for further device optimization. Here, we show that introducing a thin interlayer of poly(4-vinylpyridine) (PVP) between the perovskite film and the hole transport layer reduces nonradiative recombination. Employing such a PVP interlayer, we reach an open-circuit voltage of 1.20 V for the best devices and a stabilized efficiency of 20.7%. The beneficial effect of the PVP interlayer is proven by statistical analysis of various samples, many of those showing an open-circuit voltage larger than 1.17 V, and a 30 mV increase in average compared to unmodified samples. The reduced... 

    Coupled ionic-electronic equivalent circuit to describe asymmetric rise and decay of photovoltage profile in perovskite solar cells

    , Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) Ebadi, F ; Aryanpour, M ; Mohammadpour, R ; Taghavinia, N ; Sharif University of Technology
    Nature Publishing Group  2019
    Abstract
    In this research, we employed transient photo-voltage rise and decay measurements to investigate the origin of slow unsymmetrical rise and decay profiles in single and triple cation perovskite solar cells. Drastic changes in photo-voltage decay profile were observed upon insertion of Br−, Cs+ and FA+ ions into perovskite structures. In order to explain our observations, the activation energy for ionic defects was measured and an equivalent circuit model was proposed containing both electrical and ionic components. The electrical branch consists of a diode, the bulk capacitance and resistances for charge transport and recombination. In parallel we introduced an ionic branch describing the... 

    A mechanical model for morphological response of endothelial cells under combined wall shear stress and cyclic stretch loadings

    , Article Biomechanics and Modeling in Mechanobiology ; Volume 15, Issue 5 , 2016 , Pages 1229-1243 ; 16177959 (ISSN) Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    Springer Verlag 
    Abstract
    The shape and morphology of endothelial cells (ECs) lining the blood vessels are a good indicator for atheroprone and atheroprotected sites. ECs of blood vessels experience both wall shear stress (WSS) and cyclic stretch (CS). These mechanical stimuli influence the shape and morphology of ECs. A few models have been proposed for predicting the morphology of ECs under WSS or CS. In the present study, a mathematical cell population model is developed to simulate the morphology of ECs under combined WSS and CS conditions. The model considers the cytoskeletal filaments, cell–cell interactions, and cell–extracellular matrix interactions. In addition, the reorientation and polymerization of... 

    Effect of cell concentration on the acylation of penicillin G enzymatic reaction in immobilized cells

    , Article Scientia Iranica ; Volume 16, Issue 1 , 2009 , Pages 69-73 ; 10263098 (ISSN) Barin, M ; Otadi, M ; Khorasheh, F ; Kheirolomoom, A ; Sharif University of Technology
    2009
    Abstract
    E.coli was immobilized by entrapment within calcium alginate beads using cell suspensions of different concentrations. The immobilization procedure resulted in beads with a homogeneous cell distribution, referred to as a Non-overlapping Cell (NC) configuration. If cells within the beads were allowed to grow, the NC configuration would transform into a Clustered Cell (CC) configuration as a, result of cell growth. Enzyme activity and substrate conversion were obtained for NC and CC configurations of different cell density, using penicillin G acylation by penicillin G acylase, to produce. 6-amino penicillanic acid. Enzyme activity and conversion were found to depend on both cell concentration... 

    Controlling differentiation of stem cells for developing personalized organ-on-chip platforms

    , Article Advanced Healthcare Materials ; Volume 7, Issue 2 , 2018 ; 21922640 (ISSN) Geraili, A ; Jafari, P ; Sheikh Hassani, M ; Heidary Araghi, B ; Mohammadi, M. H ; Ghafari, A. M ; Hassanpour Tamrin, S ; Pezeshgi Modarres, H ; Rezaei Kolahchi, A ; Ahadian, S ; Sanati Nezhad, A ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Abstract
    Organ-on-chip (OOC) platforms have attracted attentions of pharmaceutical companies as powerful tools for screening of existing drugs and development of new drug candidates. OOCs have primarily used human cell lines or primary cells to develop biomimetic tissue models. However, the ability of human stem cells in unlimited self-renewal and differentiation into multiple lineages has made them attractive for OOCs. The microfluidic technology has enabled precise control of stem cell differentiation using soluble factors, biophysical cues, and electromagnetic signals. This study discusses different tissue- and organ-on-chip platforms (i.e., skin, brain, blood–brain barrier, bone marrow, heart,... 

    Curcumin-reduced graphene oxide sheets and their effects on human breast cancer cells

    , Article Materials Science and Engineering C ; Volume 55 , 2015 , Pages 482-489 ; 09284931 (ISSN) Hatamie, S ; Akhavan, O ; Sadrnezhaad, S. K ; Ahadian, M. M ; Shirolkar, M. M ; Wang, H. Q ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    Curcumin (as a natural reductant material) was utilized for green reduction and functionalization of chemically exfoliated graphene oxide (GO) sheets. The π-π attachment of the curcumin molecules onto the curcumin-reduced graphene oxide (rGO) sheets was confirmed by Raman and Fourier transform infrared spectroscopies. Zeta potential of the GO sheets decreased from about - 40 mV to - 20 mV, after the green reduction and functionalization. The probable cytotoxicity of the curcumin-rGO sheets was studied through their interactions with two human breast cancer cell lines (MDA-MB-231 and SKBR3 cell lines) and a normal cell line (mouse fibroblast L929 cell line). The curcumin-rGO sheet with... 

    Microfluidic systems for stem cell-based neural tissue engineering

    , Article Lab on a Chip - Miniaturisation for Chemistry and Biology ; Volume 16, Issue 14 , 2016 , Pages 2551-2571 ; 14730197 (ISSN) Karimi, M ; Bahrami, S ; Mirshekari, H ; Moosavi Basri, S. M ; Bakhshian Nik, A ; Aref, A. R ; Akbari, M ; Hamblin, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Abstract
    Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise... 

    Design of two Inertial-based microfluidic devices for cancer cell separation from Blood: A serpentine inertial device and an integrated inertial and magnetophoretic device

    , Article Chemical Engineering Science ; 2021 ; 00092509 (ISSN) Nasiri, R ; Shamloo, A ; Akbari, J ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    The separation of cancer cells from a heterogeneous biological sample such as blood plays a vital role in cancer study and future treatments. In this paper, we designed and investigated two microfluidic devices for cancer cell separation, including a serpentine inertial device and an integrated inertial-magnetophoretic device. Firstly, numerical modeling was carried out to study the fluid flow, particles’ trajectories in the inertial device. Then the device was fabricated using soft photolithography and suspension of two types of microparticles with the size of 10 and 15 µm were injected into the microchannel separately to investigate the particles’ trajectories and focusing behavior at... 

    Flexible bactericidal graphene oxide–chitosan layers for stem cell proliferation [electronic resource]

    , Article Journal of Applied Surface Science ; 15 May 2014, Volume 301, Pages 456–462 Mazaheri, M ; Akhavan, O ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    Abstract
    Graphene oxide (GO)–chitosan composite layers with stacked layer structures were synthesized using chemically exfoliated GO sheets (with lateral dimensions of ∼1 μm and thickness of ∼1 nm), and applied as antibacterial and flexible nanostructured templates for stem cell proliferation. By increasing the GO content from zero to 6 wt%, the strength and elastic modulus of the layers increased ∼80% and 45%, respectively. Similar to the chitosan layer, the GO–chitosan composite layers showed significant antibacterial activity (>77% inactivation after only 3 h) against Staphylococcus aureus bacteria. Surface density of the actin cytoskeleton fibers of human mesenchymal stem cells (hMSCs) cultured... 

    Nanodiamonds for surface engineering of orthopedic implants: Enhanced biocompatibility in human osteosarcoma cell culture [electronic resource]

    , Article Diamond and Related Materials ; Volume 40, 2013, Pages 107-114 Mansoorianfar, M. (Mojtaba) ; Shokrgozar, M. A ; Mehrjoo, M ; Tamjid, E ; Simchi, A ; Sharif University of Technology
    Abstract
    Recently, nanodiamonds have attracted interest in biomedical applications such as drug delivery, targeted cancer therapies, fabrication of tissue scaffolds, and biosensors. We incorporated diamond nanoparticles in alginate–bioactive glass films by electrophoretic process to prepare functional coatings for biomedical implants. Turbidity examination by time-resolved laser transmittance measurement revealed that a stable multi-component aqueous suspension of alginate, bioactive glass and diamond particles could be obtained at concentrations of 0.6, 1.3, and 0.65 g/l, respectively. Uniform films with ~ 5 μm thickness were deposited on 316 stainless steel foils by employing constant field...