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Ghadim E.E.,Islamic Azad University at Tehran | Rashidi N.,University of Tehran | Kimiagar S.,University of Tehran | Akhavan O.,Sharif University of Technology | And 2 more authors.
Applied Surface Science | Year: 2014

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 the GO sheets decreased from 49% to 21% after 10 min laser irradiation. This reduction efficiency was comparable with the efficiency achieved by hydrazine which yielded the O/C ratio of 15% at 80 °C after 10 min. Using Raman spectroscopy it was found that the pulsed laser reduction method resulted in nearly no aggregation of the reduced GO sheets in the ammonia solution. These results can help to further promotion and application of pulsed lasers in environment friendly reduction of GO. © 2014 Elsevier B.V. All rights reserved.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory | Hashemi E.,Iran National Institute of Genetic Engineering and Biotechnology | Akbari E.,Sharif University of Technology
Carbon | Year: 2015

In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and chromosomal aberrations of the spermatozoa after ∼8 weeks from the first weekly injection were assigned to the involvement of the NGO in spermatogenesis of the mice. The uptake of the NGO in the testis could also increase the generation of reactive oxygen species in semen of the mice. Moreover, semen of the NGO-treated mice (containing the damaged spermatozoa) might disturb the hormone secretion and pregnant functionality of female mice (∼44, 35 and 59% reduction in fertility, gestation ability and multi-production capability) and also viability of the next generation (∼15% reduction in postnatal viability of delivered pups). © 2015 Elsevier Ltd.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory | Hashemi E.,Iran National Institute of Genetic Engineering and Biotechnology | Rahighi R.,Sharif University of Technology
Nanoscale | Year: 2014

Graphene oxide nanoplatelets (GONPs) with extremely sharp edges (lateral dimensions ∼20-200 nm and thicknesses <2 nm) were applied in extraction of the overexpressed guanine synthesized in the cytoplasm of leukemia cells. The blood serums containing the extracted guanine were used in differential pulse voltammetry (DPV) with reduced graphene oxide nanowall (rGONW) electrodes to develop fast and ultra-sensitive electrochemical detection of leukemia cells at leukemia fractions (LFs) of ∼10-11 (as the lower detection limit). The stability of the DPV signals obtained by oxidation of the extracted guanine on the rGONWs was studied after 20 cycles. Without the guanine extraction, the DPV peaks relating to guanine oxidation of normal and abnormal cells overlapped at LFs <10-9, and consequently, the performance of rGONWs alone was limited at this level. As a benchmark, the DPV using glassy carbon electrodes was able to detect only LFs ∼ 10-2. The ultra-sensitivity obtained by this combination method (guanine extraction by GONPs and then guanine oxidation by rGONWs) is five orders of magnitude better than the sensitivity of the best current technologies (e.g., specific mutations by polymerase chain reaction) which not only are expensive, but also require a few days for diagnosis. This journal is © The Royal Society of Chemistry.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory | Rahighi R.,Sharif University of Technology | Abdolahad M.,University of Tehran
Carbon | Year: 2014

Mg2+-charged spongy graphene electrodes (SGEs) were fabricated by using electrophoretic deposition of chemically exfoliated graphene oxide sheets on graphite rods. The SGEs were able to present two distinguishable signals (originated from electrochemical oxidation of guanine) in differential pulse voltammetry (DPV) of leukemia and normal blood cells, in contrast to glassy carbon electrodes giving only one overlapped peak. Hence, the SGEs were applied in fast (60 min) and ultra sensitive detection of leukemia (single abnormal cells in ∼109 normal cells) in a blood serum. The sensitivity obtained by the SGEs was three orders of magnitude better than that of the best available and current technologies (e.g., specific mutations by polymerase chain reaction with detection limit of one abnormal cell in ∼106 normal cells) which not only are expensive, but also require several days for incubation. Significant variations in DPV signals of the SGEs after the first electrochemical cycle indicated that the best performance of the SGEs can be achieved only at the first cycle. The linear dynamic detection behavior of the SGEs was investigated in wide concentration range of 1.0 × 105-0.1 cell/mL. The lower detection limit was estimated ∼0.02 cell/mL, based on the current resolution obtained by the SGEs. © 2014 Elsevier Ltd. All rights reserved.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory | Shirazian S.A.,Sharif University of Technology | Rahighi R.,Sharif University of Technology
Carbon | Year: 2016

Graphene oxide foam (GOF) layers with thicknesses of ∼15-50 μm and density of ∼10 graphene oxide (GO) sheets/μm were fabricated by precipitation of chemically exfoliated GO sheets in an aqueous suspension at ∼80 °C under UV irradiation. Then, rolled GOFs with desirable scales were developed as electrically conductive 3D-scaffolds and applied in directional growth of neural fibers, through differentiation of human neural stem cells (hNSCs) into neurons under an electrical stimulation. X-ray photoelectron spectroscopy indicated that the UV irradiation resulted in partial deoxygenation of the layers. Scanning electron microscopy and Raman spectroscopy confirmed the presence of multilayer GO sheets in the foam structure. The electrical sheet resistance of the GOFs was found low enough to produce the electrical stimulation currents used in differentiation of the neural cells, under low voltages. Rolling the GOFs (with hydrophilic surfaces) resulted in formation of cross-sections with superhydrophilic characteristics, inducing effective proliferation and differentiation of the hNSCs throughout the pores and interfaces of the scaffold. The electrical stimulation induced more proliferation of the cells and acceleration of the differentiation into neurons (rather than glia). These results suggest the GOFs as flexible and conductive scaffolds for regeneration of nervous systems and tissue engineering. © 2015 Elsevier Ltd. All rights reserved.


Nehra A.,Nanobiotechnology Research Laboratory | Pal Singh K.,Govind Ballabh Pant University of Agriculture & Technology
Biosensors and Bioelectronics | Year: 2015

Recently, as metal-, polymer-, and carbon-based biocompatible nanomaterials have been increasingly incorporated into biosensing applications, with various nanostructures having been used to increase the efficacy and sensitivity of most of the detecting devices, including field effect transistor (FET)-based devices. These nanomaterial-based methods also became the ideal for the amalgamation of biomolecules, especially for the fabrication of ultrasensitive, low-cost, and robust FET-based biosensors; these are categorically very successful at binding the target specified entities in the confined gated micro-region for high functionality. Furthermore, the contemplation of nanomaterial-based FET biosensors to various applications encompasses the desire for detection of many targets with high selectivity, and specificity. We assess how such devices have empowered the achievement of elevated biosensor performance in terms of high sensitivity, selectivity and low detection limits. We review the recent literature here to illustrate the diversity of FET-based biosensors, based on various kinds of nanomaterials in different applications and sum up that graphene or its assisted composite based FET devices are comparatively more efficient and sensitive with highest signal to noise ratio. Lastly, the future prospects and limitations of the field are also discussed. © 2015 Elsevier B.V.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory
Journal of Materials Chemistry B | Year: 2014

An effective and self-organized differentiation of human neural stem cells (hNSCs) into neurons was developed by the pulsed laser stimulation of the cells on graphene films (prepared by drop-casting a GO suspension onto quartz substrates). The effects of graphene oxide (GO) and hydrazine-reduced graphene oxide (rGO) sheets on the proliferation of hNSCs were examined. The higher proliferation of the cells on the GO was assigned to its better hydrophilicity. On the other hand, the rGO sheets, which have significantly better electrical conductivity than GO, exhibited more differentiation of the cells into neurons. The pulsed laser stimulation not only resulted in an accelerated differentiation of hNSCs into neurons (rather than glia), but also caused the self-organization of a radial neuronal network on the surface of the rGO sheets, due to the radial stress induced by the surface thermal gradient originating from the center of the laser spot. The higher thermal conductivity of the rGO sheets (compared to the GO sheets and the quartz substrate) provided better outward heat flow from the center of the laser spot, and consequently, prevented extra local heating at the position of the laser spot. These results can encourage further investigations into the advantages of graphene in the self-organized differentiation of hNSCs using pulsed laser stimulation. This journal is © the Partner Organisations 2014.


Akhavan O.,Sharif University of Technology | Meidanchi A.,Sharif University of Technology | Meidanchi A.,Payame Noor University | Ghaderi E.,Nanobiotechnology Research Laboratory | Khoei S.,Tehran University of Medical Sciences
Journal of Materials Chemistry B | Year: 2014

A magneto-photothermal therapy for cancer (in vitro photothermal therapy of prostate cancer cells and in vivo photothermal therapy of human glioblastoma tumors in the presence of an external magnetic field) was developed using superparamagnetic zinc ferrite spinel (ZnFe2O4)-reduced graphene oxide (rGO) nanostructures (with various graphene contents). In vitro application of a low concentration (10 μg mL-1) of the ZnFe 2O4-rGO (20 wt%) nanostructures under a short time period (∼1 min) of near-infrared (NIR) irradiation (with a laser power of 7.5 W cm-2) resulted in an excellent destruction of the prostate cancer cells, in the presence of a magnetic field (∼1 Tesla) used for localizing the nanomaterials at the laser spot. However, in the absence of a magnetic field, ZnFe2O4-rGO and also rGO alone (10 μg mL -1) resulted in only ∼50% cell destruction at the most in the short photothermal therapy and also in a typical radiotherapy (∼2 min gamma irradiation with a dose of 2 Gy). The minimum concentrations required for the successful application of the nanostructures in the photothermal and radiotherapeutic methods were found to be ∼100 and 1000 μg mL -1, while in the proposed magneto-photothermal therapy it was only ∼10 μg mL-1. The in vivo feasibility of this method was also examined on mice bearing glioblastoma tumors. Furthermore, the localization of the magnetic nanomaterials injected into the tumors was studied in the presence and absence of an external magnetic field. These results will stimulate more applications of magnetic graphene-containing composites in highly efficient photothermal therapy. © the Partner Organisations 2014.


Akhavan O.,Sharif University of Technology | Ghaderi E.,Nanobiotechnology Research Laboratory | Shirazian S.A.,Sharif University of Technology
Colloids and Surfaces B: Biointerfaces | Year: 2015

Reduced graphene oxide nanomeshes (rGONMs), as p-type semiconductors with band-gap energy of ~1. eV, were developed and applied in near infrared (NIR) laser stimulation of human neural stem cells (hNSCs) into neurons. The biocompatibility of the rGONMs in growth of hNSCs was found similar to that of the graphene oxide (GO) sheets. Proliferation of the hNSCs on the GONMs was assigned to the excess oxygen functional groups formed on edge defects of the GONMs, resulting in superhydrophilicity of the surface. Under NIR laser stimulation, the graphene layers (especially the rGONMs) exhibited significant cell differentiations, including more elongations of the cells and higher differentiation of neurons than glia. The higher hNSC differentiation on the rGONM than the reduced GO (rGO) was assigned to the stimulation effects of the low-energy photoexcited electrons injected from the rGONM semiconductors into the cells, while the high-energy photoelectrons of the rGO (as a zero band-gap semiconductor) could suppress the cell proliferation and/or even cause cell damages. Using conventional heating of the culture media up to ~43. °C (the temperature typically reached under the laser irradiation), no significant differentiation was observed in dark. This further confirmed the role of photoelectrons in the hNSC differentiation. © 2014 Elsevier B.V.

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