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3D Bioprinting of oxygenated cell-laden gelatin methacryloyl constructs
, Article Advanced Healthcare Materials ; Volume 9, Issue 15 , 2020 ; Darabi, M. A ; Nasiri, R ; Sangabathuni, S ; Ertas, Y. N ; Alem, H ; Hosseini, V ; Shamloo, A ; Nasr, A. S ; Ahadian, S ; Dokmeci, M. R ; Khademhosseini, A ; Ashammakhi, N ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Cell survival during the early stages of transplantation and before new blood vessels formation is a major challenge in translational applications of 3D bioprinted tissues. Supplementing oxygen (O2) to transplanted cells via an O2 generating source such as calcium peroxide (CPO) is an attractive approach to ensure cell viability. Calcium peroxide also produces calcium hydroxide that reduces the viscosity of bioinks, which is a limiting factor for bioprinting. Therefore, adapting this solution into 3D bioprinting is of significant importance. In this study, a gelatin methacryloyl (GelMA) bioink that is optimized in terms of pH and viscosity is developed. The improved rheological properties...
Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite
, Article Journal of Bioactive and Compatible Polymers ; Volume 27, Issue 5 , January , 2012 , Pages 467-480 ; 08839115 (ISSN) ; Shokrollahi, P ; Atai, M ; Omidian, H ; Bagheri, R ; Sharif University of Technology
SAGE
2012
Abstract
Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy...
Fabrication and characterization of scaffolds containing different amounts of allantoin for skin tissue engineering
, Article Scientific Reports ; Volume 11, Issue 1 , 2021 ; 20452322 (ISSN) ; Shamloo, A ; Bahadoran, M ; Moravvej, H ; Sharif University of Technology
Nature Research
2021
Abstract
Using the skin tissue engineering approach is a way to help the body to recover its lost skin in cases that the spontaneous healing process is either impossible or inadequate, such as severe wounds or burns. In the present study, chitosan/gelatin-based scaffolds containing 0.25, 0.5, 0.75, and 1% allantoin were created to improve the wounds’ healing process. EDC and NHS were used to cross-link the samples, which were further freeze-dried. Different in-vitro methods were utilized to characterize the specimens, including SEM imaging, PBS absorption and degradation tests, mechanical experiments, allantoin release profile assessment, antibacterial assay, and cell viability and adhesion tests....
A mechanobiological mathematical model of liver metabolism
, Article Biotechnology and Bioengineering ; Volume 117, Issue 9 , 5 June , 2020 , Pages 2861-2874 ; Firoozabadi, B ; Munn, L. L ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
The liver plays a complex role in metabolism and detoxification, and better tools are needed to understand its function and to develop liver-targeted therapies. In this study, we establish a mechanobiological model of liver transport and hepatocyte biology to elucidate the metabolism of urea and albumin, the production/detoxification of ammonia, and consumption of oxygen and nutrients. Since hepatocellular shear stress (SS) can influence the enzymatic activities of liver, the effect of SS on the urea and albumin synthesis are empirically modeled through the mechanotransduction mechanisms. The results demonstrate that the rheology and dynamics of the sinusoid flow can significantly affect...
Fabrication and characterization of an injectable reinforced composite scaffold for cartilage tissue engineering: An in vitro study
, Article Biomedical Materials (Bristol) ; Volume 16, Issue 4 , 2021 ; 17486041 (ISSN) ; Mashayekhan, S ; Zarei, F ; Sayyahpour, F. A ; Taghiyar, L ; Eslaminejad, M. B ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
There are limitations in current medications of articular cartilage injuries. Although injectable bioactive hydrogels are promising options, they have decreased biomechanical performance. Researchers should consider many factors when providing solutions to overcome these challenges. In this study, we created an injectable composite hydrogel from chitosan and human acellular cartilage extracellular matrix (ECM) particles. In order to enhance its mechanical properties, we reinforced this hydrogel with microporous microspheres composed of the same materials as the structural building blocks of the scaffold. Articular cartilage from human donors was decellularized by a combination of physical,...
Silane functionalization of nanodiamond for polymer nanocomposites-effect of degree of silanization
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 506 , 2016 , Pages 254-263 ; 09277757 (ISSN) ; Shojaei, A ; Sharif University of Technology
Elsevier B.V
2016
Abstract
The silanization of nanodiamond (ND) was successfully carried out by using the esterification reaction of hydrolyzed vinyltrimethoxysilane (VTS) in alcoholic solution. The surface carboxylic group of ND was first enhanced by thermal oxidation to increase the degree of esterification reaction. The extent of silane functionalization of ND was controlled by varying the weight ratio of VTS and oxidized ND (oxND), from 2:1 to 10:1 (w/w) in the functionalization reaction medium. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) revealed that the highest degree of silanization occurred at VTS/oxND of 5:1 (w/w), while more silane concentrations resulted in...
Appraising the impacts of SiO2, ZnO and TiO2 nanoparticles on rheological properties and shale inhibition of water-based drilling muds
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 581 , 2019 ; 09277757 (ISSN) ; Shams, R ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In recent decades, utilizing of water-based muds (WBMs) in drilling oil and gas wells is ever increasing comparing to oil-based muds and synthetic-based muds due to the lower environmental issues. However, the main drawbacks with WBMs are rheological properties inefficiency and shale swelling which have caused attentions turn to improvement of WBMs’ rheological properties. In this study, the effects of various nanoparticles (NPs) namely titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) on improving rheological properties and shale recovery rate of a WBM sample at two temperatures (25 and 50 °C) were investigated. The concentrations of NPs in the base mud were set at 0.01,...
Design and fabrication of a two-phase diamond nanoparticle aided fast PCR device
, Article Analytica Chimica Acta ; Volume 1068 , 2019 , Pages 28-40 ; 00032670 (ISSN) ; Ghazimirsaeed, E ; Shamloo, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Polymerase Chain Reaction (PCR) is an important and prevalent technique in biotechnology because of its crucial role in cloning DNA fragments and diagnostic applications. In the present study, a high-throughput two-phase PCR device is designed and fabricated which utilizes a serpentine microchannel together with a spiral structure. The former is for the droplet-generation and mixing and the latter is for the thermal cycling process. Moreover, the effect of diamond nanoparticles (diamondNP) on the performance of PCR is also investigated while using commercial PCR devices and the fabricated PCR device designed in this study. Using numerical simulation, it is shown that within the simple and...
Injectable in situ forming kartogenin-loaded chitosan hydrogel with tunable rheological properties for cartilage tissue engineering
, Article Colloids and Surfaces B: Biointerfaces ; Volume 192 , 2020 ; Chen, Y ; Wang, D ; Bagheri, R ; Solouk, A ; Wu, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Limited regeneration capacity of cartilage can be addressed by tissue engineering approaches including localized delivery of bioactive agents using biomaterials. Although chitosan hydrogels have been considered as appropriate candidates for these purposes, however, their poor mechanical properties limit their real applications. Here, we develop in situ forming chitosan hydrogels with enhanced shear modulus by chemical modification of chitosan using N-(β-maleimidopropyloxy) succinimide ester (BMPS). Moreover, we utilize β-Glycerophosphate (β-GP) in the hydrogels for achieving thermosensitivity. We investigate the effects of BMPS, β-GP and chitosan concentration on rheological and swelling...
Preparation and characterization of self-electrical stimuli conductive gellan based nano scaffold for nerve regeneration containing chopped short spun nanofibers of PVDF/MCM41 and polyaniline/graphene nanoparticles: Physical, mechanical and morphological studies
, Article International Journal of Biological Macromolecules ; Volume 167 , 2021 , Pages 881-893 ; 01418130 (ISSN) ; S. A., A. R ; H Shirazi, F ; Nemati, N. H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Conductive self -electrical stimuli bioactive scaffolds could be used the potential for peripheral nerve regeneration with the maximum efficiency. To produce such conductive self-electrical stimuli bioactive scaffolds, chopped spun piezoelectric nanofibers of polyvinylidene fluoride/mesoporous silica nanoparticle (PVDF/MCM41) are prepared and incorporated in gellan/polyaniline/graphene (gellan/PAG) nanocomposites which have been previously prepared by incorporation of polyaniline/graphene (PAG) nanoparticles in gellan gel at 80 °C. Highly conductive binary doped polyaniline/graphene nanoparticles are prepared by chemical oxidative polymerization of aniline monomer using in-suite...
Fast dynamic interfacial tension measurements and dilational rheology of interfacial layers by using the capillary pressure technique
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 407 , August , 2012 , Pages 159-168 ; 09277757 (ISSN) ; Krägel, J ; Makievski, A. V ; Kovalchuk, V. I ; Kovalchuk, N. M ; Mucic, N ; Loglio, G ; Pandolfini, P ; Karbaschi, M ; Miller, R ; Sharif University of Technology
Elsevier
2012
Abstract
The oscillating drop and bubble analyzer (ODBA) is an experimental set-up based on the measurement of capillary pressure under static and dynamic conditions. It allows studies of slow and fast dynamic surface and interfacial tensions, following different growing and oscillating drop or bubble protocols, as well as determination of the dilational interfacial visco-elasticity of liquid interfacial layers. For the visco-elasticity studies, drops or bubbles are subjected to harmonic oscillations of area or volume in a broad frequency range, and the resulting harmonic capillary pressure response is analyzed by Fourier analysis. Also, transient relaxations can be easily performed, which are of...
Dynamics of rear stagnant cap formation at the surface of rising bubbles in surfactant solutions at large reynolds and marangoni numbers and for slow sorption kinetics
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 492 , 2016 , Pages 127-137 ; 09277757 (ISSN) ; Lotfi, M ; Kovalchuk, V. I ; Bastani, D ; Miller, R ; Sharif University of Technology
Elsevier
2016
Abstract
In spite of the high level in the theory of steady rear stagnant caps (RSC) and its influence on steady rising, its practical application is mostly impossible because the coefficients for the adsorption and desorption rates are separately unknown. The determination of ka and kd separately is an actual task for the adsorption dynamics as whole. While steady RSC and steady rising retardation by surfactants are described in literature in details, only few papers are devoted to the modeling of the decelerated rising. Moreover, steady rising depends on the ratio ka/kd and its investigation is not helpful for the determination of kd. In contrast a possibility to determine kd (or ka independently)...
Interfacial instability of growing drop: experimental study and conceptual analysis
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 347, Issue 1-3 , 2009 , Pages 167-174 ; 09277757 (ISSN) ; Bastani, D ; Kragel, J ; Miller, R ; Sharif University of Technology
Elsevier
2009
Abstract
Capillary pressure experiments were performed at the water/hexane interface including adsorption and mass exchange of hexanol under different conditions. The results from growing drop experiments show that instabilities due to Marangoni convection not only depend on the same parameters as have been reported for quasi-static interfaces, such as direction of mass transfer, distribution coefficient and ratio of diffusion coefficients, but also on the experimental conditions such as dispersed phase flow rate, capillary tip size, size of growing drop and its lifetime. Based on a new flow expansion model for mass transfer, a new approach is presented for data analysis, which includes the various...
Construction of scaffolds composed of acellular cardiac extracellular matrix for myocardial tissue engineering
, Article Biologicals ; Volume 53 , 2018 , Pages 10-18 ; 10451056 (ISSN) ; Mashayekhan, S ; Ghanbari Asl, S ; Hajebrahimi, Z ; Sharif University of Technology
Academic Press
2018
Abstract
High rates of mortality and morbidity stemming from cardiovascular diseases unveil extreme limitations in current therapies despite enormous advances in medical and pharmaceutical sciences. Following myocardial infarction (MI), parts of myocardium undergo irreversible remodeling and is substituted by a scar tissue which eventually leads to heart failure (HF). To address this issue, cardiac patches have been utilized to initiate myocardial regeneration. In this study, a porous cardiac patch is fabricated using a mixture of decellularized myocardium extracellular matrix (ECM) and chitosan (CS). Results of rheological measurements, SEM, biodegradation test, and MTT assay showed that the...
Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: A mechanistic study
, Article Colloids and Surfaces B: Biointerfaces ; Vol. 117 , May , 2014 , pp. 457-465 ; ISSN: 09277765 ; Zeinolabedini Hezave, A ; Mohammadi, S ; Niazi, A ; Ayatollahi, S ; Sharif University of Technology
Abstract
During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding...
Rheology of interfacial layers
, Article Current Opinion in Colloid and Interface Science ; Vol. 19, issue. 6 , 2014 , pp. 514-519 ; ISSN: 13590294 ; Lotfi, M ; Kragel, J ; Javadi, A ; Bastani, D ; Miller, R ; Sharif University of Technology
Abstract
Dilational and shear viscoelasticities are important properties of interfacial layers. These quantities are particularly relevant in all systems which contain a huge internal interfacial area such as foams and emulsions. Therefore, also the 3D rheological behavior of foams or emulsions studied by respective methods is superimposed by the 2D interfacial rheology.We report on recent developments in dilational and shear rheology from an experimental point of view as well as discuss the state of the art of the underlying theories. Examples of most relevant experiments are also presented and discussed. Although not yet extensively investigated, the links between bulk rheology of foams and...
Investigation of segregation of large particles in a pressurized fluidized bed with a high velocity gas: A discrete particle simulation
, Article Powder Technology ; Volume 246 , September , 2013 , Pages 398-412 ; 00325910 (ISSN) ; Hosseini, S. A ; Soleimani, R ; Sharif University of Technology
2013
Abstract
A numerical study on mixing/segregation phenomena in a pressurized fluidized bed with large particles of Geldart D type of binary density but same diameter with high velocity gas was performed by the use of discrete particle simulation. Particle mixtures are composed of spherical particles with 2mm diameter and 1g/cm3 flotsam density and different jetsam densities of 1.25, 2 and 2.5g/cm3 with jetsam volume fraction of 0.5. The particles are initially packed approaching perfect mixing state in a rectangular bed and then fluidized by gas uniformly injected at the bottom of the bed. Effect of increase of pressure and density ratio was investigated and mixing/segregation behavior is discussed in...
Quantitative determination of optical trapping strength and viscoelastic moduli inside living cells
, Article Physical Biology ; Volume 10, Issue 4 , 2013 ; 14783967 (ISSN) ; Richardson, A. C ; Reihani, S. N. S ; Oddershede, L. B ; Berg Sorensen, K ; Sharif University of Technology
2013
Abstract
With the success of in vitro single-molecule force measurements obtained in recent years, the next step is to perform quantitative force measurements inside a living cell. Optical traps have proven excellent tools for manipulation, also in vivo, where they can be essentially non-invasive under correct wavelength and exposure conditions. It is a pre-requisite for in vivo quantitative force measurements that a precise and reliable force calibration of the tweezers is performed. There are well-established calibration protocols in purely viscous environments; however, as the cellular cytoplasm is viscoelastic, it would be incorrect to use a calibration procedure relying on a viscous environment....
Breakup of microdroplets in asymmetric T junctions
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 87, Issue 5 , 2013 ; 15393755 (ISSN) ; Salari, A ; Shafii, M. B ; Sharif University of Technology
2013
Abstract
Symmetric T junctions have been used widely in microfluidics to generate equal-sized microdroplets, which are applicable in drug delivery systems. A newly proposed method for generating unequal-sized microdroplets at a T junction is investigated theoretically and experimentally. Asymmetric T junctions with branches of identical lengths and different cross sections are utilized for this aim. An equation for the critical breakup of droplets at asymmetric T junctions and one for determining the breakup point of droplets are developed. A good agreement was observed between the theories (present and previous) and the experiments
Thin liquid film flow over substrates with two topographical features
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 87, Issue 2 , 2013 ; 15393755 (ISSN) ; Moosavi, A ; Sharif University of Technology
2013
Abstract
A multicomponent lattice Boltzmann scheme is used to investigate the surface coating of substrates with two topographical features by a gravity-driven thin liquid film. The considered topographies are U- and V-shaped grooves and mounds. For the case of substrates with two grooves, our results indicate that for each of the grooves there is a critical width such that if the groove width is larger than the critical width, the groove can be coated successfully. The critical width of each groove depends on the capillary number, the contact angle, the geometry, and the depth of that groove. The second groove critical width depends on, in addition, the geometry and the depth of the first groove;...