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    Functionalized carbon nanotubes in ZnO thin films for photoinactivation of bacteria

    , Article Materials Chemistry and Physics ; Volume 130, Issue 1-2 , October , 2011 , Pages 598-602 ; 02540584 (ISSN) Akhavan, O ; Azimirad, R ; Safa, S ; Sharif University of Technology
    Two types of unfunctionalized and functionalized multi-wall carbon nanotubes (MWCNTs) were prepared to be applied in fabrication of MWCNT-ZnO nanocomposite thin films with various MWCNT contents. X-ray photoelectron spectroscopy indicated formation of functional groups on surface of the functionalized MWCNTs in the MWCNT-ZnO nanocomposite. Formation of the effective carbonaceous bonds between the ZnO and the MWCNTs was also investigated through photoinactivation of Escherichia coli bacteria on surface of the both unfunctionalized and functionalized MWCNT-ZnO nanocomposites. The functionalized MWCNT-ZnO nanocomposites showed significantly stronger photoinactivation of the bacteria than the... 

    CuO/Cu(OH)2 hierarchical nanostructures as bactericidal photocatalysts

    , Article Journal of Materials Chemistry ; Volume 21, Issue 26 , May , 2011 , Pages 9634-9640 ; 09599428 (ISSN) Akhavan, O ; Azimirad, R ; Safa, S ; Hasani, E ; Sharif University of Technology
    Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed -OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situ oxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60°C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the... 

    Silver nanoparticles within vertically aligned multi-wall carbon nanotubes with open tips for antibacterial purposes

    , Article Journal of Materials Chemistry ; Volume 21, Issue 2 , Oct , 2011 , Pages 387-393 ; 09599428 (ISSN) Akhavan, O ; Abdolahad, M ; Abdi, Y ; Mohajerzadeh, S ; Sharif University of Technology
    Vertically aligned multi-wall carbon nanotube (CNT) arrays were fabricated in tip-growth mode on Ni/Si substrates using plasma enhanced chemical vapor deposition. In a purification process including hydrogenation and acid washing of the Ni/CNTs, the oxygen-containing functional groups were substantially reduced and a wide hollow core at the tip of the CNTs was formed by removing the Ni seeds. Sol-gel silver nanoparticles were deposited on the surface of the unpurified Ni/CNTs, while they could also be embedded within the hollow core of the Ni-removed CNTs. The persistency of the silver ions in the Ni-removed Ag-CNTs in comparison to the release of the silver ions from the Ag-Ni/CNTs in a... 

    Hydrothermally synthesized CuO powders for photocatalytic inactivation of bacteria

    , Article Acta Physica Polonica A ; Volume 127, Issue 6 , 2015 , Pages 1727-1731 ; 05874246 (ISSN) Azimirad, R ; Safa, S ; Akhavan, O ; Sharif University of Technology
    Various morphologies of monoclinic CuO powders were synthesized by hydrothermal treatment of copper nitrate, copper acetate or copper sulfate. The synthesized samples were characterized by scanning electron microscopy, X-ray diffractometry, the Fourier transform infrared spectroscopy, and diffuse reflectance spectrophotometry. Antibacterial activity of the samples was studied against Escherichia coli bacteria in dark and under visible light irradiation. Although the different precursors yielded the same band gap energies (≈1.6 eV) for the synthesized CuO samples, they resulted in various morphologies (hierarchy of stabilized micro/nanostructures), specific surface areas, concentrations of... 

    Visible light photo-induced antibacterial activity of CNT-doped TiO 2 thin films with various CNT contents

    , Article Journal of Materials Chemistry ; Volume 20, Issue 35 , Jun , 2010 , Pages 7386-7392 ; 09599428 (ISSN) Akhavan, O ; Azimirad, R ; Safa, S ; Larijani, M. M ; Sharif University of Technology
    Carbon nanotube (CNT)-doped TiO2 thin films with various CNT contents were synthesized by sol-gel method for visible light photoinactivation of Escherichia coli bacteria. Post annealing of the CNT-doped TiO2 thin films at 450 °C resulted in anatase TiO2 and formation of Ti-C and Ti-O-C carbonaceous bonds in the film. By increasing the CNT content, the thin films could further inactivate the bacteria in the dark. Meanwhile, as the CNT content increased from zero to 40 wt% the effective optical band gap energy of the CNT-doped TiO2 thin films annealed at 450 °C decreased from 3.2-3.3 to less than ∼2.8 eV providing light absorption in the visible region. Concerning this, visible light... 

    Physicochemical and antibacterial properties of chitosan-polyvinylpyrrolidone films containing self-organized graphene oxide nanolayers

    , Article Journal of Applied Polymer Science ; Volume 133, Issue 11 , 2016 ; 00218995 (ISSN) Mahmoudi, N ; Ostadhossein, F ; Simchi, A ; Sharif University of Technology
    John Wiley and Sons Inc  2016
    Chitosan films have a great potential to be used for wound dressing and food-packaging applications if their physicochemical properties including water vapor permeability, optical transparency, and hydrophilicity are tailored to practical demands. To address these points, in this study, chitosan (CS) was combined with polyvinylpyrrolidone (PVP) and graphene oxide (GO) nanosheets (with a thickness of ∼1 nm and lateral dimensions of few micrometers). Flexible and transparent films with a high antibacterial capacity were prepared by solvent casting methods. By controlling the evaporation rate of the utilized solvent (1 vol % acidic acid in deionized water), self-organization of GO in the... 

    Silver oxide nanoparticles-decorated tantala nanotubes for enhanced antibacterial activity and osseointegration of Ti6Al4V

    , Article Materials and Design ; Volume 154 , 2018 , Pages 28-40 ; 02641275 (ISSN) Sarraf, M ; Dabbagh, A ; Abdul Razak, B ; Nasiri Tabrizi, B ; Hosseini, H. R. M ; Saber Samandari, S ; Abu Kasim, N. H ; Yean, L. K ; Sukiman, N. L ; Sharif University of Technology
    Elsevier Ltd  2018
    A long-term antibacterial activity of implants without compromising their biocompatibility is highly desirable to minimize the biomaterial-associated infections. Although tantalum oxide nanotubes (Ta2O5 NTs) are promising coating materials for orthodontics and orthopedics applications, their insufficient antibacterial activity retains vulnerability to post-implantation infections. This study aimed to endow antibacterial characteristics to the Ta2O5 NTs-coated Ti6Al4V substrates by decoration of silver oxide nanoparticles (Ag2O NPs). The well-adherent Ta2O5 NTs were grown via anodization of a pure tantalum (Ta) layer coated by physical vapor deposition (PVD) on the Ti6Al4V substrates. The... 

    Highly-ordered TiO2 nanotubes decorated with Ag2O nanoparticles for improved biofunctionality of Ti6Al4V

    , Article Surface and Coatings Technology ; Volume 349 , 2018 , Pages 1008-1017 ; 02578972 (ISSN) Sarraf, M ; Dabbagh, A ; Abdul Razak, B ; Mahmoodian, R ; Nasiri Tabrizi, B ; Madaah Hosseini, H. R ; Saber Samandari, S ; Abu Kasim, N. H ; Abdullah, H ; Sukiman, N. L ; Sharif University of Technology
    Elsevier B.V  2018
    The nanotubular arrays of titanium dioxide (TiO2 NTs) have recently received considerable interest for fabrication of dental and orthopedic implants. However, their antibacterial activity requires substantial improvement for the potential infections minimization, without compromise of their biocompatibility. In this work, TiO2 NTs were developed on Ti6Al4V substrates via anodization at a constant potential of 60 V for 60 min, followed by heat treatment at 500 °C for 90 min. Physical vapor deposition (PVD) was further employed to decorate silver oxide nanoparticles (Ag2O NPs) on the nanotubular edges. The results indicated that the highly-ordered TiO2 NTs with decorated Ag2O NPs could promote... 

    Enhancement of antibacterial properties of Ag nanorods by electric field

    , Article Science and Technology of Advanced Materials ; Volume 10, Issue 1 , 2009 ; 14686996 (ISSN) Akhavan, O ; Ghaderi, E ; Sharif University of Technology
    The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20-60 nm and a length of 260-550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 °C in an Ar+H2 environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {100}... 

    Hyperthermia response of PEGylated magnetic graphene nanocomposites for heating applications and accelerate antibacterial activity using magnetic fluid hyperthermia

    , Article Applied Physics A: Materials Science and Processing ; Volume 126, Issue 4 , 2020 Hatamie, S ; Shih, P. J ; Soufi Zomorod, M ; Heravi, P ; Ahadian, M. M ; Hatami, N ; Sharif University of Technology
    Springer  2020
    In this research work, graphene/cobalt nanocomposites are functionalized with polyethylene glycol (PEG) to be a platform for theranostics application and antibacterial activity. The non-covalent functionalization of PEG on the surfaces of nanocomposites improved their stability and diminished their cytotoxicity. The PEGylated nanocomposites are demonstrated to allow simultaneous administration of two cancer therapy methods such as magnetic fluids hyperthermia (MFH) which is carried out by converting magnetic energy into heat through ferromagnetic cobalt nanoparticles and heat generation through near-infrared optical absorption by the reduced graphene oxide. A concise simulation is carried... 

    Graphene/Cuo2nanoshuttles with controllable release of oxygen nanobubbles promoting interruption of bacterial respiration

    , Article ACS Applied Materials and Interfaces ; Volume 12, Issue 32 , 2020 , Pages 35813-35825 Jannesari, M ; Akhavan, O ; Madaah Hosseini, H. R ; Bakhshi, B ; Sharif University of Technology
    American Chemical Society  2020
    An oxygen nanoshuttle based on a reduced graphene oxide/copper peroxide (rGO/CuO2) nanocomposite has been presented to deliver in situ oxygen nanobubbles (O2 NBs) for combating bacterial infections. In the presence of rGO, the solid source of oxygen (i.e., CuO2) was decomposed (in response to environmental conditions such as pH and temperature) into O2 NBs in a more controllable and long-lasting trend (from 60 to 144 h). In a neutral buffer, the O2 NBs experienced growth and collapse evolutions, creating a dynamic micro-nanoenvironment around the nanocomposite. In addition to effective battling against methicillin-resistant Staphylococcus aureus bacteria, the O2 NBs demonstrated superior... 

    Multifunctional 3D hierarchical bioactive green carbon-based nanocomposites

    , Article ACS Sustainable Chemistry and Engineering ; Volume 9, Issue 26 , 2021 , Pages 8706-8720 ; 21680485 (ISSN) Rabiee, N ; Bagherzadeh, M ; Ghadiri, A. M ; Kiani, M ; Fatahi, Y ; Tavakolizadeh, M ; Pourjavadi, A ; Jouyandeh, M ; Saeb, M. R ; Mozafari, M ; Shokouhimehr, M ; Varma, R. S ; Sharif University of Technology
    American Chemical Society  2021
    Carbon-based nanocarriers such as multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) have shown promising delivery capabilities due to their low immunogenicity, superior internalization, and suitable cell penetration efficiency. Herein, a molecular engineering strategy is advanced for the one-pot synthesized rGO/MWCNT/Fe3O4/ZnO to enhance the stability of the nanocarrier in the biological matrix; green synthesized ZnO was responsible for water uptake and reduced cytotoxicity, while Fe3O4controlled the cellular internalization for gene delivery. Surface morphology of the ensuing nanocomposite was correlated with photocatalytic and gene delivery (CRISPR/Cas9) features. For... 

    Nanomechanical properties of MscL α helices: A steered molecular dynamics study

    , Article Channels ; Volume 11, Issue 3 , 2017 , Pages 209-223 ; 19336950 (ISSN) Bavi, N ; Bavi, O ; Vossoughi, M ; Naghdabadi, R ; Hill, A. P ; Martinac, B ; Jamali, Y ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Gating of mechanosensitive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We used a constant-force steered molecular dynamics (SMD) approach to perform unidirectional pulling tests on all the helices of MscL in M. tuberculosis and E. coli homologs. Using this method, we could overcome the issues encountered with the commonly used constant-velocity SMD simulations, such as low mechanical stability of the helix during... 

    Chaperones promote remarkable solubilization of salmonella enterica serovar enteritidis flagellin expressed in escherichia coli

    , Article Protein and Peptide Letters ; Volume 27, Issue 3 , 2020 , Pages 210-218 Bakhtiarvand, B ; Sadeghi, Z ; Tarahomjoo, S ; Yaghmaie, S ; Sharif University of Technology
    Bentham Science Publishers  2020
    Background: Flagellin of Salmonella enterica serovar Enteritidis (SEF) stimulates immune responses to both itself and coapplied antigens. It is therefore used in vaccine development and immunotherapy. Removal of pathogenic S. enterica ser. Enteritidis from SEF production process is advantageous due to the process safety improvement. The protein solubility analysis using SDS-PAGE indicated that 53.49% of SEF expressed in Escherichia coli formed inclusion bodies. However, the protein recovery from inclusion bodies requires a complex process with a low yield. Objective: We thus aim to study possibility of enhancing SEF expression in E. coli in soluble form using chemical and molecular... 

    Ag-doped magnetic metal organic framework as a novel nanostructured material for highly efficient antibacterial activity

    , Article Environmental Research ; Volume 188 , 2020 Rahmati, Z ; Abdi, J ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
    Academic Press Inc  2020
    In the last decades, numerous attempts have been made to prevent microbial pollution spreading, using antibacterial agents. Zeolitic imidazolate framework-8 (ZIF-8) belongs to a subgroup of metal organic frameworks (MOFs) merits of attention due to the zinc ion clusters and its effective antibacterial activity. In this work, Ag-doped magnetic microporous γ-Fe2O3@SiO2@ZIF-8-Ag (FSZ-Ag) was successfully synthesized by a facile methodology in room temperature and used as an antibacterial agent against the growth of the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Several characterization methods were applied to analyze the properties of the materials, and the... 

    Synthesis of Zeolite-Based NanoComposites and Investigation of their Catalytic Activities

    , M.Sc. Thesis Sharif University of Technology Padervand, Mohsen (Author) ; Gholami, Mohammad Reza (Supervisor)
    Polyagent photocatalysts based on the zeolite including TiO2, Ag and AgBr prepared by Sol-gel method. Ag and AgBr prevent of electron-hole recombination and enhance photocatalytic activity. Prepared catalysts were characterized by different analysis method including XRD, SEM, EDX, FTIR and BET techniques. Catalyst activities were investigated from two aspects: in first step the activities of catalyst were investigated for degradation of AB92 dye. The effect of different factors such as: catalyst concentration, dye concentration, pH and scavenger (sodium thiosulphate) on efficiency and reaction rate were investigated. The optimazed values for all conditions specified, then catalyst activities... 

    Optimization for Production & Purification of Asparaginase Enzyme

    , M.Sc. Thesis Sharif University of Technology Dashtban Kenari, Laleh (Author) ; Alemzadeh, Iran (Supervisor) ; Maghsodi, Vida (Supervisor)
    The enzyme L-Asparaginase (L-asparagine amidohydrolase, EC has been thoroughly researched by many researchers worldwide because of its immensely useful medical applications. It can catalyze the hydrolysis of L-asparagine to L-aspartic acid and ammonia that is effective for the cure of leukemia, especially for puerile Acute Lymphocytic Leukemia [ALL] and Lymphosarcomas. The present study discusses the studies carried out for the optimal production of the enzyme from Escherichia coli ATCC 11303. For extraction of the intracellular enzyme, Sonication is more useful method for cell disruption than alkali lysis and enzymatic method. We improved Luria Bertani (LB) media (tryptone 1% w/v,... 

    Synthesis of Fe3O4 Core-Shell Nanoparticles; Embedding Cu, Ag, Au Metals in the Surfaces that Were Modified by PPG and PEG Polymers and Investigation of Antibacterial Properties of These Composites

    , M.Sc. Thesis Sharif University of Technology Kiani Karanji, Ahmad (Author) ; Gholami, Mohammad Reza (Supervisor) ; Haghighi, Saeed (Co-Advisor)
    In this project, Fe3O4 magnetic nanoparticles were prepared by co-precipitation method. For protecting them against oxidation and also avoiding from direct contact between core and additional materials that probably makes unwanted reactions, the surface of nanoparticles were coated by SiO2 layer. Being easy to modify and having the control of interactions between nanoparticles are the advantages of coating nanoparticles with silica. The obtained Fe3O4@SiO2 core-shell nanoparticles were covered by two types of polymer (PPG and PEG). The basis of the composite was characterized by VSM, TGA, SEM, XRD, and FT-IR analytical methods.
    The antibacterial activities of Copper, Silver and Gold... 

    Synthesis of Antibacterial Nanoparticle for Packaging Food Application

    , M.Sc. Thesis Sharif University of Technology Radan, Niloofar (Author) ; Yaghmaei, Soheila (Supervisor) ; Ghobadinezhad, Zahra (Co-Supervisor)
    Food spoilage cased by food-borne pathogens and microorganisms is a serious problem in the food and packaging industry. Then, the demand for antibacterial agents in food packaging is growing. The antibacterial efficacy of some nanocomposites has been recognized and exploited in various industries, including the packaging industry. Also, metal organic frameworks due to their porous structure, are used in various fields such as food packaging. The purpose of this work, is synthesize hybrid nanocomposite that have promising antibacterial activity for preparation of food packaging films. Carboxymethyl cellulose is a derivative of cellulose fiber. The use of carboxymethyl cellulose as... 

    Graphene oxide sheets involved in vertically aligned zinc oxide nanowires for visible light photoinactivation of bacteria

    , Article Journal of Alloys and Compounds ; Vol. 612 , 2014 , pp. 380-385 ; ISSN: 09258388 Nourmohammadi, A ; Rahighi, R ; Akhavan, O ; Moshfegh, A ; Sharif University of Technology
    Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO...