An Update on Graphene Oxide: Applications and Toxicity

Abstract

Graphene oxide (GO) has attracted much attention in the past few years because of its interesting and promising electrical, thermal, mechanical, and structural properties. These properties can be altered, as GO can be readily functionalized. Brodie synthesized the GO in 1859 by reacting graphite with KClO 3 in the presence of fuming HNO 3 ; the reaction took 3−4 days to complete at 333 K. Since then, various schemes have been developed to reduce the reaction time, increase the yield, and minimize the release of toxic byproducts (NO 2 and N 2 O 4 ). The modified Hummers method has been widely accepted to produce GO in bulk. Due to its versatile characteristics, GO has a wide range of applications in different fields like tissue engineering, photocatalysis, catalysis, and biomedical applications. Its porous structure is considered appropriate for tissue and organ regeneration. Various branches of tissue engineering are being extensively explored, such as bone, neural, dentistry, cartilage, and skin tissue engineering. The band gap of GO can be easily tuned, and therefore it has a wide range of photocatalytic applications as well: the degradation of organic contaminants, hydrogen generation, and CO 2 reduction, etc. GO could be a potential nanocarrier in drug delivery systems, gene delivery, biological sensing, and antibacterial nanocomposites due to its large surface area and high density, as it is highly functionalized with oxygen-containing functional groups. GO or its composites are found to be toxic to various biological species and as also discussed in this review. It has been observed that superoxide dismutase (SOD) and reactive oxygen species (ROS) levels gradually increase over a period after GO is introduced in the biological systems. Hence, GO at specific concentrations is toxic for various species like earthworms, Chironomus riparius, Zebrafish, etc.

Radiosensitization of Nasopharyngeal Carcinoma by Graphene Oxide Nanosheets to Reduce Bcl-2 Level

“…It was reported that the formation of slight folds and crimped edges could be ascribed to the large surface energy of the thin GO nanosheets and the introduced oxygen functional groups. 15,16 The 3D AFM images show the GO surface morphology, structure, and roughness information with nanometer resolution in Figure 1(g-i). In addition, the peculiar microstructure of GO nanosheets might alter the cellular microenvironment of cell surviving, and as reported that GO had abundant oxygencontaining groups on its basal plane.…”

Graphene family in cancer therapy: recent progress in cancer gene/drug delivery applications

“…274,275 The translation of microRNAs has also been shown to be influenced by them in a few cell lines. 276 Aside from cancer, geno-toxicity is a less prevalent but nonetheless important side effect of graphene exposure. 277 For instance, GQDs have been reported to cause oxidative stress which affects cell DNA (in vitro).…”

Nanomaterials for Cortisol Sensing

“…Carbon-based fluorescent nanoparticles (CNPs) [ 37 , 38 , 39 ], such as carbon dots (CD), graphene quantum dots (GQD), and polymer dots (PD), have a narrow size distribution ranging from about 3.0 to 6.0 nm and an average diameter of about 5.1 nm. Graphene oxide is a 2D nanostructure based on SP2-carbon atoms, which contains different oxygen atoms due to the carbon oxidation reaction [ 40 ]. Metal nanoflowers are composed of metal phosphates such as cobalt [ 41 ], copper, manganese, zinc, ferrous, and calcium salts as inorganic components, having larger diameters concerning carbon and gold nanoparticles (100–500 nm).…”