Purified Graphene Oxide Dispersions Lack In Vitro Cytotoxicity and In Vivo Pathogenicity

Abstract

Prompted by the excitement from the description of single layer graphene, increased attention for potential applications in the biomedical field has been recently placed on graphene oxide (GO). Determination of the opportunities and limitations that GO offers in biomedicine are particularly prone to inaccuracies due to wide variability in the preparation methodologies of GO material in different laboratories, that results in significant variation in the purity of the material and the yield of the oxidation reactions, primarily the Hummers method used. Herein, the fabrication of highly pure, colloidally stable, and evenly dispersed GO in physiologically-relevant aqueous buffers in comparison to conventional GO is investigated. The purified GO material is thoroughly characterized by a battery of techniques, and is shown to consist of single layer GO sheets of lateral dimensions below 500 nm. The cytotoxic impact of the GO in vitro and its inflammation profile in vivo is investigated. The purified GO prepared and characterized here does not induce significant cytotoxic responses in vitro, or inflammation and granuloma formation in vivo following intraperitoneal injection. This is one of the initial steps towards determination of the safety risks associated with GO material that may be interacting with living tissue.

Hypochlorite degrades 2D graphene oxide sheets faster than 1D oxidised carbon nanotubes and nanohorns

“…The Raman spectral fingerprints obtained for the synthesised GO, OxMWNT and OxNH were comparable to that reported previously in the literature using identical or similar oxidation processes. 15,33 To then monitor degradation, other characterisation techniques were used including visual observation (Fig. 2a) and UV-Vis absorption (Fig.…”

“…This has also been demonstrated by previous reports in the literature. 15,33 An explanation for the colouration is that during synthesis, the oxidation of the pristine graphite removes carbon atoms from participating in the extensive electron delocalisation present in graphene. This initially opens the band gap of the component graphene in the longer wavelength regions of the visible spectrum as a result of the reduction in electron delocalisation.…”

“…13 Some studies suggest the ability of graphene, for example, to penetrate cell membranes and potentially damage the cell interior, 14 while others report biocompatibility. 15 Further studies are therefore warranted in this area to conclude on the toxicological profile of CNMs. Regarding degradability, several studies have investigated and demonstrated the degradation of CNMs including graphene using enzymes, such as lignin peroxidase 16 or horseradish peroxidase.…”

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

“…165 However, purified GO showed no significant cytotoxicity in epithelial lung carcinoma cells up to 100 μg/mL, and no inflammation or granuloma formation (up to 50 μg/animal dose exposure) in vivo. 166 Lammel et al 167 showed that GO has a dose-dependent toxic effect through plasma membrane damage, that is, loss of plasma membrane structural integrity, which was associated with a strong physical interaction of GO with the phospholipid bilayer. Further, they showed that GO could penetrate the plasma membrane, resulting in altered cell morphology and an augmented number of apoptotic cells.…”

Current applications of graphene oxide in nanomedicine

“…93 Lateral dimensions of GO nano-sheets do not affect drug-loading capacity but could have limitations regarding blood-brain transport, renal clearance, and biodegradation. 94 The success of a GO-based drug delivery vehicle is dependent on three factors. 78 The first is constructing a carrier with an optimal loading capacity.…”