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    Influence of Au thickness on the performance of plasmonic enhanced hematite photoanodes

    , Article RSC Advances ; Volume 3, Issue 39 , 2013 , Pages 17837-17842 ; 20462069 (ISSN) Akbari, M ; Kikhavani, M. R ; Sheshyekani, K ; Dabirian, A ; Sharif University of Technology
    The surface plasmon effect of Au nanostructures placed on the surface of hematite has recently been used to enhance light absorption within its carrier collection distance of 10 nm from the water-hematite interface. Despite significant narrow band absorption enhancements in the visible region, the reported enhancements in the overall performance of the cell under standard AM1.5 sunlight illumination are not significant. We numerically design an array of Au stripes on the surface of an extremely thin layer of hematite to maximize the number of charge carriers that can reach the hematite-water interface and explore the optical processes involved. The lateral dimensions and in particular the... 

    Superparamagnetic zinc ferrite spinel-graphene nanostructures for fast wastewater purification

    , Article Carbon ; Vol. 69 , April , 2014 , pp. 230-238 ; ISSN: 00086223 Meidanchi, A ; Akhavan, O ; Sharif University of Technology
    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... 

    Nontoxic concentrations of PEGylated graphene nanoribbons for selective cancer cell imaging and photothermal therapy

    , Article Journal of Materials Chemistry ; Volume 22, Issue 38 , 2012 , Pages 20626-20633 ; 09599428 (ISSN) Akhavan, O ; Ghaderi, E ; Emamy, H ; Sharif University of Technology
    Reduced graphene oxide nanoribbons functionalized by amphiphilic polyethylene glycol (rGONR-PEG) were applied to attach arginine-glycine-aspartic acid (RGD)-based peptide and cyanine dye 3 (cy3) for targeting ανβ3 integrin receptors on human glioblastoma cell line U87MG and its selective fluorescence imaging, respectively. The rGONR-PEG suspension with a concentration of 100 μg mL -1 showed ∼14 and 2.4-fold higher near infrared (NIR) absorption at 808 nm than GONR (with dimensions of ∼80 nm × 1 μm) and rGO-PEG sheets (with lateral dimensions of ∼2 μm), respectively. The rGONR-PEG-cy3-RGD exhibited highly efficient NIR photothermal therapy performance (concentrations ≥1.0 μg mL-1 resulted in... 

    Size-dependent genotoxicity of graphene nanoplatelets in human stem cells

    , Article Biomaterials ; Volume 33, Issue 32 , 2012 , Pages 8017-8025 ; 01429612 (ISSN) Akhavan, O ; Ghaderi, E ; Akhavan, A ; Sharif University of Technology
    Reduced graphene oxide nanoplatelets (rGONPs) were synthesized by sonication of covalently PEGylated GO sheets followed by a chemical reduction using hydrazine and bovine serum albumin. Human mesenchymal stem cells (hMSCs), as a fundamental factor in tissue engineering, were isolated from umbilical cord blood (as a recently proposed source for extracting fresh hMSCs) to investigate, for the first time, the size-dependent cyto- and geno-toxic effects of the rGONPs on the cells. The cell viability test showed significant cell destructions by 1.0 μg/mL rGONPs with average lateral dimensions (ALDs) of 11±4 nm, while the rGO sheets with ALDs of 3.8±0.4 μm could exhibit a significant cytotoxic...