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The three-dimensional (3D) nano scaffold of the cellulose acetate (CA) containing graphene/cobalt nanocomposite (0.1 wt.%) was fabricated via electrospinning technique, and its impact on bone regeneration was investigated. Through this aim, bone marrow mesenchymal stem cells are cultured on the CA, and graphene/cobalt (rGO/Co)/CA nanocomposite scaffold surfaces and the samples are treated under low frequency alternative magnetic field (75 Hz). The scaffolds are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal studies (TG/DSC). The proliferation behavior of stem cells on CA, and rGO/Co/CA nano scaffolds are studied by MTT assay, show their biocompability after 14 days of cell seeding. The 6-diamidino-2-phenylindole (DAPI) staining is used to confirm the morality of stem cell for duration of seven days. The nanocomposite scaffold is enhanced for extremely higher proliferation compared to the bare CA scaffold. The acceleration on osteogenic differentiation on the bone mesenchymal stem cell is enhanced within 48 h when rGO/Co/CA scaffold is placed under alternative current magnetic field (ACMF). Furthermore, the acceleration of the stem cells differentiation for the rGO/Co/CA scaffold under ACMF corresponds to the induced scaffold surface roughness caused by graphene sheets, the metallic behavior of graphene and the responding of the nanocomposite magnetic parts (i.e., cobalt nanoparticles) while applying 75 Hz frequency. Using reverse transcription polymerase chain reaction (RT-PCR) analysis, the superior effect of ACMF on scaffold contain magnetic graphene nanocomposite is confirmed to produce bone related genes within 14 days. [ABSTRACT FROM AUTHOR]

Graphene/cobalt nanocomposites are promising materials for theranostic nanomedicine applications, which are defined as the ability to diagnose, provide targeted therapy and monitor the response to the therapy. In this study, the composites were synthesized via chemical method, using graphene oxide as the source material and assembling cobalt nanoparticles of 15 nm over the surface of graphene sheets. Various characterization techniques were then employed to reveal the morphology, size and structure of the nanocomposites, such as X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and ultraviolet visible spectroscopy. Using ion-coupled plasma optical emission spectroscopy, cobalt concentration in the nanocomposites was found to be 80%. In addition, cytotoxicity of graphene/cobalt nanocomposites were evaluated using 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide or MTT assay. MTT viability assay exhibited biocompatibility to L929 mouse fibroblasts cells, under a high dose of 100 μg/mL over 24 h. Hyperthermia results showed the superior conversion of electromagnetic energy into heat at 350 kHz frequency for 0.01 and 0.005 g/L of the nanocomposites solution. The measured heat generation and energy transfer results were anticipated by the finite element analysis, conducted for the 3D structure. Magnetic resonance imaging characteristics also showed that negatively charge graphene/cobalt nanocomposites are suitable for T 1 -weighted imaging. [ABSTRACT FROM AUTHOR]

Hereby a simple, low-cost and scalable route is being presented for preparation of binder-free electrodes of reduced graphene oxide (RGO) on Ni foam (Ni/Gr). In this regard, the Ni foams are dipped in graphene oxide (GO) slurry. Next, the GO loaded Ni foams are kept in a freeze dryer for 24 h and heated up to 800 °C in an inert atmosphere. In this approach, the amount of active materials can be easily optimized for capacitive deionization (CDI). The characterization of Ni/Gr electrodes revealed a 3D porous assembly of RGO on Ni substrate which is helpful for the fast ion diffusion and rapid electron transport. The electrochemical performance of the prepared electrodes is investigated in both 3-electrode system and symmetric 2-electrode assembly. Then, the prepared electrodes are applied for capacitive deionization (CDI) studies in saline water samples. Results revealed a specific capacitance of about 77 F/g (in 1 M of NaCl at 2.5 A/g) and an ion removal capacitance of 22.3 mg/g (in 50 mL of 500 ppm of NaCl) for the fabricated system. The stability of the CDI system was surveyed in 500 ppm of NaCl solution which showed 65% of the initial capacity after 200 consecutive cycles (9 days). These results indicate that this method is efficient for both supercapacitive energy storage applications and CDI technology. [Display omitted] • Simple binder-free porous graphene on Ni substrate electrodes is synthesized. • The amount of active materials can be easily optimized for capacitive deionization. • Electrochemical adsorption capacity of the electrode is 22.3 mg/g in 500 ppm NaCl. • The electrochemical properties of electrode are compared with PVDF containing electrode. • Electrodes showed 65% of the initial capacity after 200 cycles (9 days) of capacitive deionization. [ABSTRACT FROM AUTHOR]

New membrane materials and processes have been extensively developed due to urgent needs for much more economic separation processes. Recently, graphene has been confirmed to be an excellent separation membrane. As there is no support in the obtained three-dimensional (3D) architecture constructed from tubular graphene network, it is possible to take full advantage of the large surface of graphene. In this study 3D graphene aerogels were synthesized by a simple method and modified to adjust hydrophilicity of the samples to achieve high liquid volumetric rate. Modified samples were used for the filtration of the enzymes including amylase, cellulase, lipase and protease. Slightly differently interactions between enzymes and samples causing different flow rates. To investigate changes in physicochemical properties of filtered enzyme, catalytic activity and structure of untreated and filtered samples were obtained using circular dichroism spectra and colorimetric assays. The configurations and functions of cellulase, lipase and protease were maintained during the processes. The results demonstrate that 3D graphene aerogels is a promising material for enzyme filtration and keep the aim of protein filtration which is providing high quality protein sample to achieve original information from interested protein species. [ABSTRACT FROM AUTHOR]

Curcumin (as a natural reductant material) was utilized for green reduction and functionalization of chemically exfoliated graphene oxide (GO) sheets. The π–π attachment of the curcumin molecules onto the curcumin-reduced graphene oxide (rGO) sheets was confirmed by Raman and Fourier transform infrared spectroscopies. Zeta potential of the GO sheets decreased from about − 40 mV to − 20 mV, after the green reduction and functionalization. The probable cytotoxicity of the curcumin-rGO sheets was studied through their interactions with two human breast cancer cell lines (MDA-MB-231 and SKBR3 cell lines) and a normal cell line (mouse fibroblast L929 cell line). The curcumin-rGO sheet with concentrations < 70 μg/mL in the cell culture medium, not only exhibited no significant toxicity and/or cell morphological changes, but also caused some cell growths (~ 25% after 48 h incubation time). Nevertheless, at 70 μg/mL, initiation of some cell morphological changes was observed. At higher concentrations (e.g., 100 μg/mL), some slight cytotoxic effects (resulting in ~ 15 − 25% cell destruction) were detected by MTT assay. In addition, the interaction of the rGO sheets and cells resulted in apoptosis as well as morphological transformation of the cells (from elongated to roundup morphology). These results indicated the concentration-dependent toxicity of functionalized-rGO nanomaterials (here, curcumin-rGO) at the threshold concentration of ~ 100 μg/mL. [ABSTRACT FROM AUTHOR]