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

Abstract

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.

Combination of graphene oxide–silver nanoparticle nanocomposites and cisplatin enhances apoptosis and autophagy in human cervical cancer cells

“…The UV-visible spectrum of rGO exhibited a characteristic band at 263 nm, indicating the restoration of the extensive conjugated sp 2 carbon network. 22,31 However, during reduction from GO to rGO, the characteristic absorption band at 300 nm disappeared and the absorption band at 263 nm observed in the rGO spectrum, which confirms the reduction of GO and the partial restoration of the π network of rGO ( Figure 1B).…”

“…[21][22][23] Therefore, finding alternative processes becomes essential, apparently leading to biological methods that are well appreciated for their viable and environment-friendly approach, with the added advantage of providing solubility to rGO, due to its biomolecular properties. 21 Graphene and graphene-related materials have been studied extensively for cellular toxicity in various cancer cells, including human alveolar basal epithelial (A549) cells, human breast cancer cells, 22 and human ovarian cancer cells, 23 due their unique properties. Similarly, the anticancer properties of silver NPs have been investigated in various cancer cell lines, including human breast cancer cells 24 and human lung cancer cells.…”

“…48 Similarly, bacterially reduced nanographene sheets induce more toxicity than GO in human breast cancer cells. 22 Plant extract-mediated GO-AgNPs showed significant toxicity in human ovarian cancer cells over other nanomaterials, including GO, rGO, and AgNPs. Recently, de Luna et al assessed the cytotoxicity of a GO-Ag nanocomposite, pristine GO, and pristine AgNPs in two representative murine macrophages: a tumoral lineage (J774) and peritoneal macrophages collected from BALB/c mice.…”

“…36,37 The characteristic peak (002) of Gt at 26.58° disappeared after oxidation, while an additional peak at 11.7° was observed (Figure 2A), which corresponded to the (001) diffraction peak of GO. 22 rGO showed a broad peak that could be fitted by using a Lorentzian function into single broad peaks centered at 25.88°, corresponding to interlayer Figure 2B), which was due to the removal of oxygen functional groups, causing a decrease in d-spacing. Altogether, these XRD results confirmed the exfoliation and reduction processes of GO and the processes of removing intercalated water molecules and the oxide groups.…”

Graphene synthesis: a Review

“…The resultant culture was centrifuged at 10000 rpm to obtain the biomass used for rGO synthesis. 200 mg of Bacillus marisflavi biomass was added to the GO dispersion (0.5 mg/mL) and stirred for 72 h at 37°C, followed by centrifugation to remove excess bacteria [46]. While chemical methods make it possible to synthesize graphene at lower temperatures and cost, graphene obtained by such methods contains high density of surface defects.…”