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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 ; 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...
In vivo SPECT imaging of tumors by 198,199Au-labeled graphene oxide nanostructures
, Article Materials Science and Engineering C ; Vol. 45 , 2014 , pp. 196-204 ; ISSN: 09284931 ; Akhavan, O ; Rahighi, R ; Aboudzadeh, M. R ; Karimi, E ; Afarideh, H ; Sharif University of Technology
Abstract
Graphene oxide (GO) sheets functionalized by aminopropylsilyl groups (8.0 wt.%) were labeled by 198,199Au nanoparticle radioisotopes (obtained through reduction of HAuCl4 in sodium citrate solution followed by thermal neutron irradiation) for fast in vivo targeting and SPECT imaging (high purity germanium-spectrometry) of tumors. Using instant thin layer chromatography method, the physicochemical properties of the amino-functionalized GO sheets labeled by 198,199Au NPs (198,199Au@AF-GO) were found to be highly stable enough in organic phases, e.g. a human serum, to be reliably used in bioapplications. In vivo biodistribution of the 198,199Au@AF-GO composite was investigated in rats bearing...
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 ; Rahighi, R ; Akhavan, O ; Moshfegh, A ; Sharif University of Technology
Abstract
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...
Pulsed laser irradiation for environment friendly reduction of graphene oxide suspensions
, Article Applied Surface Science ; Vol. 301 , May , 2014 , pp. 183-188 ; ISSN: 01694332 ; Rashidi, N ; Kimiagar, S ; Akhavan, O ; Manouchehri, F ; Ghaderi, E ; Sharif University of Technology
Abstract
Graphene oxide (GO) sheets were synthesized through a modified Hummers' method. Using high resolution transmission electron microscopy the thickness of the GO sheets in a multilayer structure of stacked GO sheets was found ∼0.8 nm. A nanosecond pulsed laser (with wavelength of 532 nm and average power of 0.3 W) was applied for effective and environment friendly reduction of the GO sheets in an ammonia solution (pH ∼9) at room temperature conditions. The deoxygenation of the GO sheets by the pulsed laser reduction method was confirmed by using UV-visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis. Based on XPS analysis, the O/C ratio of...
Superparamagnetic zinc ferrite spinel-graphene nanostructures for fast wastewater purification
, Article Carbon ; Vol. 69 , April , 2014 , pp. 230-238 ; ISSN: 00086223 ; Akhavan, O ; Sharif University of Technology
Abstract
Superparamagnetic ZnFe2O4/reduced graphene oxide (rGO) composites containing ZnFe2O4 nanoparticles (with ∼5-20 nm sizes) attached onto rGO sheets (with ∼1 μm lateral dimensions) were synthesized by hydrothermal reaction method. By increasing the graphene content of the composite from 0 to 40 wt%, the size as well as the number of the ZnFe2O4 nanoparticles decreased and the saturated magnetization of the composites reduced from 10.2 to 1.8 emu/g, resulting in lower responses to external magnetic fields. Concerning this, the time needed for 90% separation of ZnFe2O4/rGO (40 wt%) composite from its solution (2 mg/mL in ethanol) was found 60 min in the presence of an external magnetic field (∼1...
Vertically aligned ZnO@CdS nanorod heterostructures for visible light photoinactivation of bacteria
, Article Journal of Alloys and Compounds ; Vol. 590 , 2014 , pp. 507-513 ; ISSN: 09258388 ; Akhavan, O ; Moradlou, O ; Nien, Y. T ; Moshfegh, A. Z ; Sharif University of Technology
Abstract
Vertically aligned ZnO@CdS nanorod heterostructure films with various loadings of CdS nanoparticle shell were synthesized and applied in photoinactivation of Escherichia coli bacteria under visible light irradiation. While neither the bare ZnO nanorods (with band-gap energy (Eg) of ∼3.28 eV) under visible light irradiation nor the nanorod heterostructures in dark exhibited any significant antibacterial activity, the ZnO@CdS nanorod heterostructures (with Eg ∼2.5-2.6 eV) could successfully inactivate the bacteria under visible light irradiation. Furthermore, it was found that an optimum loading of the CdS shell (corresponding to the effective thickness less than ∼15 nm) is required to achieve...
Cyto and genotoxicities of graphene oxide and reduced graphene oxide sheets on spermatozoa
, Article RSC Advances ; Vol. 4, issue. 52 , May , 2014 , pp. 27213-27223 ; ISSN: 20462069 ; Akhavan, O ; Shamsara, M ; Rahighi, R ; Esfandiar, A ; Tayefeh, A. R ; Sharif University of Technology
Abstract
Concentration-dependent cyto and genotoxicities of graphene oxide (GO) and reduced GO (rGO) sheets on spermatozoa were studied. rGO sheets with various surface chemical states were achieved using hydrazine (N2H 4) hydrothermal (HT) reactions and green tea polyphenols (GTPs). Although 0.1 μg mL-1 graphene could not change sperm viability and kinetic parameters, <40% and 20% of spermatozoa were viable and progressively motile, after 2 h incubation with 400 μg mL-1 GO or rGO, respectively. All the graphene nanomaterials induced concentration- dependent reductions of adenosine triphosphate and NAD+/NADH produced by spermatozoa for motility and metabolic activity. While GO, N 2H4-rGO, and HT-rGO...
Cytotoxicity of protein corona-graphene oxide nanoribbons on human epithelial cells
, Article Applied Surface Science ; Volume 320 , 30 November , 2014 , Pages 596-601 ; ISSN: 01694332 ; Akhavan, O ; Javanbakht, T ; Mahmoudi, M ; Yahia, L ; Sharif University of Technology
Abstract
Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell...
DNA and RNA extractions from eukaryotic and prokaryotic cells by graphene nanoplatelets
, Article RSC Advances ; Vol. 4, issue. 105 , 2014 , p. 60720-60728 ; Akhavan, O ; Shamsara, M ; Valimehr, S ; Rahighi, R ; Sharif University of Technology
Abstract
Graphene nanoplatelets with lateral dimensions of ∼50-200 nm and thicknesses <2 nm were utilized for the extraction of nucleic acids (NAs) from eukaryotic and prokaryotic cells. The graphene nanoplatelets (both chemically exfoliated graphene oxide nanoplatelets and hydrazine-reduced graphene oxide nanoplatelets) successfully extracted plasmid DNA (pDNA) from Escherichia coli bacteria, comparable to a conventional phenol-chloroform (PC) method. Furthermore, it was found that the yield of graphene nanoplatelets in genomic DNA (gDNA) and RNA extractions from embryonic stem cells (ESCs) was also comparable to the yield of the conventional methods. The effects of the graphene nanoplatelets on...
Hyperthermia-induced protein corona improves the therapeutic effects of zinc ferrite spinel-graphene sheets against cancer
, Article RSC Advances ; Vol. 4, issue. 107 , 2014 , p. 62557-62565 ; Akhavan, O ; Meidanchi, A ; Laurent, S ; Mahmoudi, M ; Sharif University of Technology
Abstract
Superparamagnetic zinc ferrite spinel-graphene nanostructures were synthesized as potential therapeutic agents in the magnetic targeted photothermal therapy of cancer and/or drug delivery. The global temperature of the solution and the local temperature at the nanoparticle (NP) surface determine the protein corona composition/content, which in turn affects the biological effects of NPs and the corresponding physiological responses. Therefore, it is rational to hypothesize that spinel-graphene nanostructures may have distinct protein corona compositions and contents, and therapeutic and toxic effects under laser irradiation. To assess this hypothesis, the effects of laser irradiation on the...
DNA-decorated graphene nanomesh for detection of chemical vapors
, Article Applied Physics Letters ; Volume 103, Issue 18 , 2013 ; 00036951 (ISSN) ; Kybert, N. J ; Dattoli, E. N ; Hee Han, G ; Lerner, M. B ; Akhavan, O ; Irajizad, A ; Charlie Johnson, A. T ; Sharif University of Technology
2013
Abstract
The promise of graphene for use as a vapor sensor motivated exploration of the vapor responses of graphene nanomesh (GNM) functionalized with single stranded DNA. Devices detected different vapor types, including carboxylic acids, aldehydes, organophosphates, and explosives. As-fabricated GNM field effect transistors (FETs) had larger vapor responses than standard graphene FETs due to the effect of oxidized edges and lattice defects. DNA-GNM devices discriminated between homologous species with detection limits of a few parts per million, with fast response and recovery. Responses varied significantly when the base sequence of the DNA was changed, making the sensor class an intriguing...
Visible light-induced photocatalytic reduction of graphene oxide by tungsten oxide thin films
, Article Applied Surface Science ; Volume 276 , 2013 , Pages 628-634 ; 01694332 (ISSN) ; Akhavan, O ; Sharif University of Technology
2013
Abstract
Tungsten oxide thin films (deposited by thermal evaporation or sol gel method) were used for photocatalytic reduction of graphene oxide (GO) platelets (synthesized through a chemical exfoliation method) on surface of the films under UV or visible light of the environment, in the absence of any aqueous ambient at room temperature. Atomic force microscopy (AFM) technique was employed to characterize surface morphology of the GO sheets and the tungsten oxide films. Moreover, using X-ray photoelectron spectroscopy (XPS), chemical state of the tungsten oxide films and the photocatalytic reduction of the GO platelets were quantitatively investigated. The better performance of the sol-gel tungsten...
Graphene: Promises, facts, opportunities, and challenges in nanomedicine
, Article Chemical Reviews ; Volume 113, Issue 5 , 2013 , Pages 3407-3424 ; 00092665 (ISSN) ; Laurent, S ; Chen, W ; Akhavan, O ; Imani, M ; Ashkarran, A. A ; Mahmoudi, M ; Sharif University of Technology
2013
Abstract
Graphene, a two-dimensional (2D) sheet of sp2-hybridized carbon atoms packed into a honeycomb lattice, has led to an explosion of interest in the field of materials science, physics, chemistry, and biotechnology since the few-layers graphene (FLG) flakes were isolated from graphite in 2004. For an extended search, derivatives of nanomedicine such as biosensing, biomedical, antibacterial, diagnosis, cancer and photothermal therapy, drug delivery, stem cell, tissue engineering, imaging, protein interaction, DNA, RNA, toxicity, and so on were also added. Since carbon nanotubes are normally described as rolled-up cylinders of graphene sheets and the controllable synthesis of nanotubes is well...
Polyphenols attached graphene nanosheets for high efficiency NIR mediated photodestruction of cancer cells
, Article Materials Science and Engineering C ; Volume 33, Issue 3 , 2013 , Pages 1498-1505 ; 09284931 (ISSN) ; Janmaleki, M ; Mohajerzadeh, S ; Akhavan, O ; Abbasi, S ; Sharif University of Technology
2013
Abstract
Green tea-reduced graphene oxide (GT-rGO) sheets have been exploited for high efficiency near infrared (NIR) photothermal therapy of HT29 and SW48 colon cancer cells. The biocompatibility of GT-rGO sheets was investigated by means of MTT assays. The polyphenol constituents of GT-rGO act as effective targeting ligands for the attachment of rGO to the surface of cancer cells, as confirmed by the cell granularity test in flow cytometry assays and also by scanning electron microscopy. The photo-thermal destruction of higher metastatic cancer cells (SW48) is found to be more than 20% higher than that of the lower metastatic one (HT29). The photo-destruction efficiency factor of the GT-rGO is...
Graphene oxide strongly inhibits amyloid beta fibrillation
, Article Nanoscale ; Volume 4, Issue 23 , 2012 , Pages 7322-7325 ; 20403364 (ISSN) ; Akhavan, O ; Ghavami, M ; Rezaee, F ; Ghiasi, S. M. A ; Sharif University of Technology
2012
Abstract
Since amyloid beta fibrillation (AβF) plays an important role in the development of neurodegenerative diseases, we investigated the effect of graphene oxide (GO) and their protein-coated surfaces on the kinetics of Aβ fibrillation in the aqueous solution. We showed that GO and their protein-covered surfaces delay the AβF process via adsorption of amyloid monomers. Also, the large available surface of GO sheets can delay the AβF process by adsorption of amyloid monomers. The inhibitory effect of the GO sheet was increased when we increase the concentration from 10% (in vitro; stimulated media) to 100% (in vivo; stimulated media). Conclusion: our results revealed that GO and their surface...
The decoration of TiO2/reduced graphene oxide by Pd and Pt nanoparticles for hydrogen gas sensing
, Article International Journal of Hydrogen Energy ; Volume 37, Issue 20 , 2012 , Pages 15423-15432 ; 03603199 (ISSN) ; Ghasemi, S ; Irajizad, A ; Akhavan, O ; Gholami, M. R ; Sharif University of Technology
Elsevier
2012
Abstract
Reduced graphene oxide (RGO) was used to improve the hydrogen sensing properties of Pd and Pt-decorated TiO2 nanoparticles by facile production routes. The TiO2 nanoparticles were synthesized by sol-gel method and coupled on GO sheets via a photoreduction process. The Pd or Pt nanoparticles were decorated on the TiO2/RGO hybrid structures by chemical reduction. X-ray photoelectron spectroscopy demonstrated that GO reduction is done by the TiO2 nanoparticles and Ti-C bonds are formed between the TiO2 and the RGO sheets as well. Gas sensing was studied with different concentrations of hydrogen ranging from 100 to 10,000 ppm at various temperatures. High sensitivity (92%) and fast response time...
Photo-destruction of cancer cells by NIR irradiation and graphene nano-sheets
, Article Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011, 13 June 2011 through 16 June 2011, Boston, MA ; Volume 3 , 2011 , Pages 236-239 ; 9781439871386 (ISBN) ; Mohajerzadeh, S ; Janmaleki, M ; Akhavan, O ; Azimi, S ; Clean Technology and Sustainable Industries Organization (CTSI); European Patent Office; Greenberg Traurig; Innovation and Materials Science Institute; Jackson Walker L.L.P ; Sharif University of Technology
2011
Abstract
The photo-thermal therapy using nano-materials has attracted great attention as an efficient strategy for the next generation of cancer treatments. Recently, photo-thermal therapy based on nano-materials that can be activated by a skin-penetrating NIR (Near Infra Red) irradiation has been suggested as a noninvasive, harmless, and highly efficient therapeutic technique. Graphene nano-layers synthesized by a bio-compatible method, with reduced toxicity, will be a suitable candidate for the photo-thermal therapeutic agent. A significant amount of heat is generated upon excitation with near-infrared light (NIR, 700-1100nm) which is transparent to biological species including skins. In this...
Melatonin as a powerful bio-antioxidant for reduction of graphene oxide
, Article Journal of Materials Chemistry ; Volume 21, Issue 29 , 2011 , Pages 10907-10914 ; 09599428 (ISSN) ; Akhavan, O ; Irajizad, A ; Sharif University of Technology
2011
Abstract
Graphene is usually synthesized through deoxygenation of graphene oxide (GO) by hydrazine as the most common and one of the strongest reducing agents. But, due to the high toxicity of hydrazine, it is not a promising reductant in large-scale production of graphene. Here, for the first time, we used melatonin (MLT), as a powerful antioxidant and a biocompatible competitor of hydrazine in reduction of GO suspension. X-ray photoelectron spectroscopy (XPS), current-voltage and optical characteristics of the sheets indicated that the deoxygenation efficiency of the GO suspensions by MLT and under heating in an alkaline condition for 3 h was comparable with the efficiency obtained by hydrazine in...
The effect of heat treatment on physical properties of nanograined (WO 3)1-x-(Fe2O3)x thin films
, Article Vacuum ; Volume 85, Issue 8 , February , 2011 , Pages 810-819 ; 0042207X (ISSN) ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
Thin films of (WO3)1-x-(Fe2O 3)x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 200-500 °C in air. Optical properties such as transmittance, reflectance, optical bangap energy, and the optical constants of the "as deposited" and the annealed films were studied using ultraviolet-visible spectrophotometry. It was shown that the annealing process changes the film optical properties which were related to Fe2O3 concentration. Moreover, using X-ray photoelectron spectroscopy, we have indicated that WO3 is stoichiometric, while iron oxide was in both FeO and Fe2O3 compositions so that the FeO composition converted to Fe2O3 after the...
Sol-gel synthesis of thermoluminescent Cd-doped ZnTe nanoparticles
, Article Indian Journal of Pure and Applied Physics ; Volume 53, Issue 12 , 2015 , Pages 804-807 ; 00195596 (ISSN) ; Akhavan, O ; Hatami, H ; Hoseinkhani, P ; Sharif University of Technology
National Institute of Science Communication and Information Resources (NISCAIR)
2015
Abstract
The Cd (3 wt%)-doped ZnTe nanoparticles with average size of 5 nm and band gap energy of 3.15 eV were synthesized by sol-gel method. The optical properties (such as band gap energy) and the size distribution of the nanoparticles have been investigated by using UV-Vis spectroscopy and transmission electron microscopy, respectively. Then, thermoluminescence property of the nanoparticles exposed to various doses of gamma radiation of Cs137 has been studied. The thermoluminescence glow peak of the nanoparticles showed a displacement from 290 to 230°C by increasing the dose of gamma radiation from 7.5 to 67.5 mSv. The thermoluminescence intensity of the synthesized Cd-doped ZnTe nanoparticles...