Search for: polyethylene-glycols
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    Synthesis of dithiocarbamates by Markovnikov addition reaction in PEG and their application in amidoalkylation of naphthols and indoles

    , Article Journal of the Brazilian Chemical Society ; Volume 26, Issue 7 , 2015 , Pages 1500-1508 ; 01035053 (ISSN) Halimehjani, A. Z ; Dadras, A ; Ramezani, M ; Shamiri, E. V ; Hooshmand, S. E ; Hashemi, M. M ; Sharif University of Technology
    Sociedade Brasileira de Quimica  2015
    Synthesis of dithiocarbamates by the one-pot three-component Markovnikov addition reaction of an amine, carbon disulfide and an alkyl vinyl ether or N-vinylpyrrolidone is reported in polyethylene glycol (PEG) under a mild and green procedure with high yields and completely regiospecific. Also, the products were used as efficient starting materials for amidoalkylation of electron-rich arenes such as naphthols and indoles  

    Experimental study and mathematical modeling of partitioning of β-amylase and amyloglucosidase in PEG-salt aqueous two-phase systems

    , Article Journal of Chemical and Engineering Data ; Volume 55, Issue 11 , 2010 , Pages 4968-4975 ; 00219568 (ISSN) Shahriari, S ; Vossoughi, M ; Taghikhani, V ; Safekordi, A. A ; Alemzadeh, I ; Sharif University of Technology
    In this study, the partitioning of β-amylase in aqueous two-phase systems (ATPS) containing polyethylene glycol (PEG) with a molar mass of 6000 and 10 000 and KH 2PO 4 at T = (301.65 and 304.65) K was experimentally studied. In addition, the partitioning of amyloglucosidase in ATPS containing polyethylene glycol with molar mass of 4000, 6000, and 10 000 in the presence of Na 2SO 4 at T = (301.65 and 305.65) K was investigated. The effects of molar mass of PEG, temperature, mass fractions of salt, and the length of the tie line on partition coefficients of the enzymes were also studied. The experimental results showed that while the partition coefficients of enzymes decrease with increasing... 

    Superior anti-biofouling properties of mPEG-modified polyurethane networks via incorporation of a hydrophobic dangling chain

    , Article Progress in Organic Coatings ; Volume 158 , September , 2021 ; 03009440 (ISSN) Golmohammadian Tehrani, A ; Makki, H ; Ghaffarian Anbaran, R ; Vakili, H ; Ghermezcheshme, H ; Zandi, N ; Sharif University of Technology
    Elsevier B.V  2021
    PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the... 

    Studying the Influence of Laponite Silicate Nanoparticles on the Mechanical and Structural Properties of Poly (Ethylene Glycol) Hydrogels, Synthesized under Mild Condition

    , M.Sc. Thesis Sharif University of Technology Nojoomi, Amirali (Author) ; Simchi, Abdolreza (Supervisor) ; Maddah Hosseini, Hamid Reza (Co-Advisor)
    Hemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting due to the lack of coagulation factors. Frequent joint and soft tissue bleeding is one the most common problems amongst these patients which can become progressively destructive for cartilage tissue in case of the late treatment. In this work, injectable PEG-based hydrogel nanocomposites with mechanical and structural properties close to cartilage tissue were fabricated. First, primary copolymers with PEG blocks of 600 g.mol-1 and 900 g.mol-1 without and with 2.5 wt.% Laponite nanoclay were synthesized by two-step thermal poly (amic acid) process. After polymer purification,... 

    The Effect of Protein Corona on Doxorubicin Release from the Magnetic Mesoporous Silica Nanoparticles and the Effect of Polyethylene Glycol Coating on drug Delivery System

    , M.Sc. Thesis Sharif University of Technology Mahmoudi, Negar (Author) ; Pourjavadi, Ali (Supervisor)
    The nanoparticles have been widely used in the field of physics, chemistry, electronics and mechanics because of their high surface area. One of their most important applications is in drug delivery systems as smart drug nanocarrier. Magnetic nanoparticles (including Fe2O3, Fe3O4) are the good candidates for this purpose. It is clear that, upon to entrance of nanoparticle into biological media (such as plasma), the surface of nanoparticles were covered by protein layers (protein corona). This layer is very stable and created new surface on the nanoparticles. The protein corona layer intracts with cellular receptors and determines the fate of nanoparticles. Protein corona covers the targeting... 

    Measurement and correlation of vapor-liquid equilibria of the aqueous poly(ethylene glycol) + sodium citrate and poly(ethylene glycol) + potassium citrate systems

    , Article Fluid Phase Equilibria ; Volume 262, Issue 1-2 , 2007 , Pages 137-148 ; 03783812 (ISSN) Kazemi, S ; Zafarani Moattar, M. T ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
    Elsevier  2007
    In this study, water activities for the ternary systems of PEG6000 + sodium citrate (Na3Cit) + H2O and PEG6000 + potassium citrate (K3Cit) + H2O have been measured using an improved isopiestic method over the entire homogeneous mixing range at 298.15 K. From these measurements, values of the vapor pressure of solutions were also determined. The experimental data for the activity of water, collected in this work, were accurately correlated with local composition based models of the NRTL, modified NRTL, Wilson and modified Wilson. The results showed that these models can accurately correlate the water activity data generated in this work. © 2007 Elsevier B.V. All rights reserved  

    Study and Preparation of Coated Drug by PEG Biopolymer (PEGylation) for Release Controlling

    , M.Sc. Thesis Sharif University of Technology Tavakoli Naeini, Ashkan (Author) ; Vossoughi, Manoochehr (Supervisor) ; Sarbolouki, Mohammad Nabi (Supervisor)
    In the first part of this work, citric acid monomer was selected to produce dendrimer through the divergent method using logical conditions (for controlling its functional groups) on the base of poly (ethylene glycol) as the core. Triblock copolymers (ABA-type) of citric acid and poly (ethylene glycol) (PCA-PEG-PCA) as biocompatible compounds were synthesized in four different molecular weights and applied as nanocarriers. The structure definition of the molecules and nanoparticles were carried out using different spectroscopy methods. Diameter of the synthesized copolymers was investigated using dynamic light scattering (DLS) experiments and transmission electron microscopy (TEM) and it was... 

    PEG-PLA-Polysccharide Injectable Nanogels for Drug Delivery

    , M.Sc. Thesis Sharif University of Technology Zeraatkar, Ehsan (Author) ; Frounchi, Masoud (Supervisor) ; Dadbin, Sousan (Supervisor)
    In recent years along with time and cost intensive process of developing new and better drugs for diseases like cancer, scientists and researchers are attempting to develop novel drug delivery systems for already existing drugs.The purpose of these novel drug delivery systems such as nanogels is controlling drug release rate as well as delivery to a specific target tissue in order to reduce side effects. One of the most commonly used drugs for cancer treatment is Doxorubicin HCl, commercially known as Adricin. In this project biodegradable and biocompatible polymers PLA and PEG were used to synthesize nanocarriers for Adricin. These nanocarriers were then dispersed in an agar hydrogel. The... 

    Some Studies on Conjugation of Nanoparticles Fe3O4 (Fe2O3) to PEG for Drug Delivery Systems

    , M.Sc. Thesis Sharif University of Technology Mohseni Ahooyi, Taha (Author) ; Vossoughi, Manouchehr (Supervisor) ; Yaghmaei, Soheila (Supervisor)
    The main strategy for treating solid cancers is based on the very early diagnosis of a malignant tumor, and in general the smaller the tumor, the greater the likelihood of successful treatment. Magnetic Resonance Imaging (MRI), based on the nuclear magnetic resonance phenomenon, provides the possibility of detecting early malignant tumors with the assistance of appropriate contrast agents. Hence, researchers continue to develop novel magnetic materials to achieve this aim. Superparamagnetic nanoparticles have become the focus of these studies because their superparamagnetic, biocompatible and hydrophilic properties would be revealed after modifying the particle surface by suitable... 

    Synthesis and Characterization of Silver/Poly (Lactic Acid) Nanocomposite and Effect of Gamma Ray

    , M.Sc. Thesis Sharif University of Technology Golestani, Maryam (Author) ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
    Nanocomposites of PLA/Ag, PLA/PEG/Ag and PLA/PEG/Oleic acid were synthesized via chemical reduction of AgNO3.The formation of nano-silver particles (Ag-NPs) started in the aqueous phase (using NaBH4 as a reducing agent) followed by transfer of the silver nanoparticles into the organic phase (PLA solution in chloroform) due to the presence of van der waals interactions between the hydroxyl groups of the PLA and the particles charges surrounded in the surface of the Ag-NPs. The nanocomposites films were prepared by the solution casting method. The XRD patterns and UV-Vis spectra of the nanocomposites demonstrated face–centered cubic (fcc) silver crystals and spherical nanoparticles... 

    Partitioning of alkaline protease from Bacillus licheniformis (ATCC 21424) using PEG-K2HPO4 aqueous two-phase system

    , Article Fluid Phase Equilibria ; Volume 337 , January , 2013 , Pages 1-5 ; 03783812 (ISSN) Yavari, M ; Pazuki, G. R ; Vossoughi, M ; Mirkhani, S. A ; Seifkordi, A. A ; Sharif University of Technology
    An aqueous two-phase system (ATPS) containing polyethylene glycol (PEG) and potassium phosphate (K2HPO4) was used for partitioning and partial purification of alkaline protease produced by Bacillus licheniformis ATCC 21424. The effect of PEG molar mass, pH and concentration of NaCl salt addition on partition coefficient, yield and purification factor (PF) for ATPS were studied. The highest partition coefficient (5.3) was achieved in an ATPS of 25% (w/w) PEG 10,000 (g/mol) and 10% (w/w) NaCl at pH 9. Cation and anion exchange chromatography was employed for purification of alkaline protease from protein mixture and the yield and PF for enzyme fractions were obtained to make a comparison... 

    Cell life cycle effects of bare and coated superparamagnetic iron oxide nanoparticles

    , Article Toxic Effects of Nanomaterials ; 2012 , Pages 53-66 ; 9781608054213 (ISBN) Mahmoudi, M ; Laurent, S ; Journeay, W. S ; Sharif University of Technology
    Due to the hopeful potential of nanoparticles in medicine, they have attracted much attention for various applications such as targeted drug/gene delivery, separation or imaging. Interaction of NPs with the biological environment can lead to a wide range of cellular responses. In order to have safe NPs for biomedical applications, the current biocompatibility researches are particularly focused on the severe toxic mechanisms which cause cells death. These mechanisms are apoptosis, autophagy and necrosis, which can also be intricately linked with the cell-life cycle, as there are various check-points and controls in a cell's life cycle to ensure appropriate division processes. Mechanisms by... 

    Sensor performance of nanostructured TiO2 thin films derived from particulate sol-gel route and polymeric fugitive agents

    , Article Sensors and Actuators, B: Chemical ; Volume 124, Issue 1 , 2007 , Pages 74-83 ; 09254005 (ISSN) Mohammadi, M. R ; Fray, D. J ; Cordero Cabrera, M. C ; Sharif University of Technology
    High specific surface area (SSA) nanocrystalline powders and dip-coated TiO2 thin films have been prepared by a particulate sol-gel route with added polymeric fugitive agents (PFAs), namely trehalose dihydrate (THD), polyethylene glycol (PEG6000) and hydroxypropyl cellulose (HPC). One of the highest SSA reported in the literature, obtained without PFA, was achieved (i.e., 181 m2/g), a value that could be increased up to 304 m2/g, 274 m2/g and 200 m2/g for PEG/TiO2, HPC/TiO2 and THD/TiO2 powders, respectively. Furthermore, the crystallite size varied from 1 nm for as-produced powders up to 4 nm for powders heat-treated at 600 °C. Thin films produced under optimised conditions showed excellent... 

    Polyethylene glycol (PEG) as a green solvent for carbon-carbon bond formation reactions

    , Article Journal of Molecular Liquids ; Volume 207 , 2015 , Pages 73-79 ; 01677322 (ISSN) Vafaeezadeh, M ; Mahmoodi Hashemi, M ; Sharif University of Technology
    In recent years, polyethylene glycol (PEG) has attracted special attention as a green and inexpensive solvent in various chemical transformations. The current critical review deals with breakthrough achievements for the applications of PEG as an alternative reaction media well-known coupling reactions such as Suzuki, Heck, Stille, Sonogashira, Hiyama and some challenging organic reactions for carbon-carbon bond formation  

    Synthesis of folate-modified, polyethylene glycol-functionalized gold nanoparticles for targeted drug delivery

    , Article Journal of Dispersion Science and Technology ; Volume 31, Issue 4 , 2010 , Pages 492-500 ; 01932691 (ISSN) Asadishad, B ; Vosoughi, M ; Alamzadeh, I ; Tavakoli, A ; Sharif University of Technology
    The chemical synthesis and in vitro drug delivery response of folate-modified, polyethylene glycol-functionalized gold nanoparticles were studied. Lysine-capped gold nanoparticles were first prepared. Subsequently, the widely used anticancer agent doxorubicin (DOX) was successfully attached to the surface of folate-modified, polyethylene glycol-functionalized gold nanoparticles. Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used to confirm the functionalization and conjugation steps in the chemical synthesis. The DOX-loading efficiency determined by UV-vis spectrometer was 80%. Drug release experiments displayed a controlled-release behavior... 

    Specific picomolar detection of a breast cancer biomarker her-2/neu protein in serum: electrocatalytically amplified electroanalysis by the aptamer/peg-modified electrode

    , Article ChemElectroChem ; Volume 4, Issue 4 , 2017 , Pages 872-879 ; 21960216 (ISSN) Salimian, R ; Kékedy Nagy, L ; Ferapontova, E. E ; Sharif University of Technology
    Wiley-VCH Verlag  2017
    Specific and sensitive electroanalysis of blood-circulating protein cancer biomarkers is often complicated by interference from serum proteins nonspecifically adsorbing at the biosensing interface and masking specific reactions of interest. Here, we have developed an electrocatalytically amplified assay for specific and sensitive analysis of human epidermal growth factor receptor-2 (HER-2/neu, a protein cancer biomarker over-expressed in breast cancers) that allows us to avoid both the interference from bovine serum albumin (BSA) and electrocatalytic amplification of the signal stemming from the specific aptamer−HER-2/neu binding. A HER-2/neu-specific thiolated aptamer sequence was... 

    Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 3 , 2017 , Pages 105-114 ; 00914037 (ISSN) Nojoomi, A ; Tamjid, E ; Simchi, A ; Bonakdar, S ; Stroeve, P ; Sharif University of Technology
    Taylor and Francis Inc  2017
    In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the... 

    Microfluidics-Enabled multimaterial maskless stereolithographic bioprinting

    , Article Advanced Materials ; Volume 30, Issue 27 , 2018 ; 09359648 (ISSN) Miri, A. K ; Nieto, D ; Iglesias, L ; Goodarzi Hosseinabadi, H ; Maharjan, S ; Ruiz Esparza, G. U ; Khoshakhlagh, P ; Manbachi, A ; Dokmeci, M. R ; Chen, S ; Shin, S. R ; Zhang, Y. S ; Khademhosseini, A ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    A stereolithography-based bioprinting platform for multimaterial fabrication of heterogeneous hydrogel constructs is presented. Dynamic patterning by a digital micromirror device, synchronized by a moving stage and a microfluidic device containing four on/off pneumatic valves, is used to create 3D constructs. The novel microfluidic device is capable of fast switching between different (cell-loaded) hydrogel bioinks, to achieve layer-by-layer multimaterial bioprinting. Compared to conventional stereolithography-based bioprinters, the system provides the unique advantage of multimaterial fabrication capability at high spatial resolution. To demonstrate the multimaterial capacity of this... 

    Wettability alteration of carbonate rock by nonionic surfactants in water-based drilling fluid

    , Article International Journal of Environmental Science and Technology ; 2018 ; 17351472 (ISSN) Kiani, M ; Ramazani SaadatAbadi, A ; Jafari Behbahani, T ; Sharif University of Technology
    Center for Environmental and Energy Research and Studies  2018
    The influx of solid or liquid particles of drilling mud into the pores of rock or mud loss phenomenon and clay swelling can sometimes lead to severe productive formation damage and cause to wettability alterations of reservoir rock from hydrophilic to oleophilic. Therefore, designing an appropriate fluid that is compatible with formation fluids and could reduce reservoir damage and increase the productivity of wells is very important. The two main mechanisms of surfactants are reduction of the surface tension and wettability alteration of rock reservoir that are effective in taking the oil. Regarding the importance of the wettability in reservoir productivity, this article is aimed to study... 

    Synthesis and characterization of a new thermosensitive chitosan-PEG diblock copolymer

    , Article Carbohydrate Polymers ; Volume 74, Issue 3 , 2008 , Pages 435-441 ; 01448617 (ISSN) Ganji, F ; Abdekhodaie, M. J ; Sharif University of Technology
    A novel thermosensitive hydrogel was synthesized by block copolymerization of monomethoxy poly(ethylene glycol) macromere (PEG) onto chitosan backbone, using potassium per sulfate as a free radical initiator. This block copolymer exhibits a thermoreversible transition from an injectable solution at low temperature to a gel at body temperature. Synthesized copolymers were characterized using FT-IR, 1H NMR, 13C NMR, and DSC techniques. Solubility test was performed to compare water and organo-solubility of chitosan before and after copolymerization. Sol-gel transition behavior was investigated using the vial inversion method and viscosity measurements. The gelation behavior makes the...