Graphene Oxide: A Nonspecific Enhancer of Cellular Growth

Abstract

There have been multiple conflicting reports about the biocompatibility and antimicrobial activity of graphene oxide. To address this, we conducted a study to characterize the antimicrobial properties of graphene oxide (GO) and its biocompatibility with mammalian cells. When GO was added to a bacterial culture at 25 μg/mL, the results showed that bacteria grew faster and to a higher optical density than cultures without GO. Scanning electron microscopy indicated that bacteria formed dense biofilms in the presence of GO. This was shown by a large mass of aggregated cells and extracellular polymeric material. Bacterial growth on filters coated with 25 and 75 μg of GO grew 2 and 3 times better than on filters without GO. Closer analysis showed that bacteria were able to attach and proliferate preferentially in areas containing the highest GO levels. Graphene oxide films failed to produce growth inhibition zones around them, indicating a lack of antibacterial properties. Also, bacteria were able to grow on GO films to 9.5 × 10(9) cells from an initial inoculation of 1.0 × 10(6), indicating that it also lacks bacteriostatic activity. Thus, silver-coated GO films were able to produce clearing zones and cell death. Also, graphene oxide was shown to greatly enhance the attachment and proliferation of mammalian cells. This study conclusively demonstrates that graphene oxide does not have intrinsic antibacterial, bacteriostatic, and cytotoxic properties in both bacteria and mammalian cells. Furthermore, graphene oxide acts as a general enhancer of cellular growth by increasing cell attachment and proliferation.

Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa

“…Recently, Ruiz et al 56 showed that bacteria grew faster and to a higher optical density when GO was added to a bacterial culture at 25 µg/mL than cultures without GO, and also they explained bacterial growth on filters coated with 25 and 75 µg of GO grew two and three times better than on filters without GO. Liu et al 32 observed strong antibacterial activity of four types of graphene-based materials (Gt, GtO, GO, and rGO).…”

The Preparation of Graphene Oxide and Its Derivatives and Their Application in Bio-Tribological Systems

“…Ruiz [116] studied the antibacterial, bacteriostatic and cytotoxic properties of GO in both bacteria and mammalian cells. The results show that bacteria in 25 μg/mL colloidal GO Luria-Bertani (LB) media grow faster than in LB media without colloidal GO, indicating that GO may be acting as a scaffold for bacterial attachment, proliferation and biofilm formation.…”

Environmental applications using graphene composites: water remediation and gas adsorption

“…Multiple recent studies have focused on the use of graphene and graphene composites in biomedical applications. 133,[228][229][230][231] From these studies, as well as other cytotoxicity studies on graphene and related compounds, 69,232-251 we are able to draw some conclusions regarding graphene's biological toxicity.…”

“…These studies have shown the use of graphene in microbial fuel cells, 249 graphene as a scaffold for bacterial growth, 228 as well as the use of bacteria as a graphene oxide reducing agent. 250,251 Various in vitro toxicity studies have been conducted to determine the toxicity of graphene towards cancer [234][235][236][237][238] and human cell lines.…”