A facile route to fabricate stable reduced graphene oxide dispersions in various media and their transparent conductive thin films

Kim²

2016

IJN

232

140

Graphene is a two-dimensional atomic crystal, and since its development it has been applied in many novel ways in both research and industry. Graphene possesses unique properties, and it has been used in many applications including sensors, batteries, fuel cells, supercapacitors, transistors, components of high-strength machinery, and display screens in mobile devices. In the past decade, the biomedical applications of graphene have attracted much interest. Graphene has been reported to have antibacterial, antiplatelet, and anticancer activities. Several salient features of graphene make it a potential candidate for biological and biomedical applications. The synthesis, toxicity, biocompatibility, and biomedical applications of graphene are fundamental issues that require thorough investigation in any kind of applications related to human welfare. Therefore, this review addresses the various methods available for the synthesis of graphene, with special reference to biological synthesis, and highlights the biological applications of graphene with a focus on cancer therapy, drug delivery, bio-imaging, and tissue engineering, together with a brief discussion of the challenges and future perspectives of graphene. We hope to provide a comprehensive review of the latest progress in research on graphene, from synthesis to applications.

Section: Synthesis Of Graphenementioning

confidence: 99%

Synthesis, toxicity, biocompatibility, and biomedical applications of graphene and graphene-related materials

Kim²

2016

IJN

232

140

“…However, strong and toxic reduction agents and surfactants are essential to reduce GO fully in an aqueous phase. 11 To solve this problem, many researchers have attempted to develop a new aqueous and environmentally friendly reduction strategy; these have included methods involving bacterial respiration, 12 polyallylamine, 13 potassium hydroxide, 14 polyvinylpyrrolidone, 15 ascorbic acid, 16 sugar, 17 baker's yeast, 18 melatonin, 19 and glucose. 20 Among the various nontoxic reduction agents, biomass has significant advantages because proteins can be used as reducing agents for the synthesis of graphene.…”

Section: Introductionmentioning

confidence: 99%

Green synthesis of graphene and its cytotoxic effects in human breast cancer cells

Han²,

Eppakayala³

et al. 2013

IJN

181

170

Background: This paper describes an environmentally friendly ("green") approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO) and bacterially reduced graphene oxide (B-rGO) on the inhibition of cell viability, reactive oxygen species (ROS) generation, and membrane integrity in human breast cancer cells. Methods: The reduction of GO was characterized by ultraviolet-visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and highresolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. Results:In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose . 60 µg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS generation, and releasing of lactate dehydrogenase. Conclusion: We developed a green and a simple approach to produce graphene using bacterial biomass as a reducing and stabilizing agent. The proposed approach confers B-rGO with great potential for various biological and biomedical applications.

“…Reduction of GO by chemical methods seems to be promising, due to its low cost and potential for large-scale production, and it is also appropriate for chemical modification and subsequent processing; however, in chemical methods, the usage of hydrazine and hydrazine derivatives as strong reducing agents for formation of graphene can be toxic or explosive and challenging to handle for larger-scale production. 6,9 Earlier, several studies reported the production of graphene using various biological systems, such as bacterial respiration, 25 poly(allylamine), 26 potassium hydroxide, 27 polyvinyl pyrrolidone, 28 ascorbic acid, 29 sugar, 30 and baker's yeast. 31 Recently, we and other researchers developed a greener approach for synthesis of graphene using various bacteria, such as Escherichia coli, 7,32 Escherichia fergusonii, 33 and Bacillus marisflavi.…”

Section: Introductionmentioning

confidence: 99%

An in vitro evaluation of graphene oxide reduced by Ganoderma spp. in human breast cancer cells (MDA-MB-231)

Han²,

Park³

et al. 2014

IJN

Background Recently, graphene and graphene-related materials have attracted much attention due their unique properties, such as their physical, chemical, and biocompatibility properties. This study aimed to determine the cytotoxic effects of graphene oxide (GO) that is reduced biologically using Ganoderma spp. mushroom extracts in MDA-MB-231 human breast cancer cells. Methods Herein, we describe a facile and green method for the reduction of GO using extracts of Ganoderma spp. as a reducing agent. GO was reduced without any hazardous chemicals in an aqueous solution, and the reduced GO was characterized using a range of analytical procedures. The Ganoderma extract (GE)-reduced GO (GE-rGO) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and atomic force microscopy. Furthermore, the toxicity of GE-rGO was evaluated using a sequence of assays such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation in human breast cancer cells (MDA-MB-231). Results The preliminary characterization of reduction of GO was confirmed by the red-shifting of the absorption peak for GE-rGO to 265 nm from 230 nm. The size of GO and GE-rGO was found to be 1,880 and 3,200 nm, respectively. X-ray diffraction results confirmed that reduction processes of GO and the processes of removing intercalated water molecules and the oxide groups. The surface functionalities and chemical natures of GO and GE-rGO were confirmed using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface morphologies of the synthesized graphene were analyzed using high-resolution scanning electron microscopy. Raman spectroscopy revealed single- and multilayer properties of GE-rGO. Atomic force microscopy images provided evidence for the formation of graphene. Furthermore, the effect of GO and GE-rGO was examined using a series of assays, such as cell viability, membrane integrity, and reactive oxygen species generation, which are key molecules involved in apoptosis. The results obtained from cell viability and lactate dehydrogenase assay suggest that GO and GE-rGO cause dose-dependent toxicity in the cells. Interestingly, it was found that biologically derived GE-rGO is more toxic to cancer cells than GO. Conclusion We describe a simple, green, nontoxic, and cost-effective approach to producing graphene using mushroom extract as a reducing and stabilizing agent. The proposed method could enable synthesis of graphene with potential biological and biomedical applications such as in cancer and angiogenic disorders. To our knowledge, this is the first report using mushroom extract as a reducing agent for the synthesis of graphene. Mushroom...