The controversial antibacterial activity of graphene-based materials

Graphene is a rapidly rising star on the horizon of materials science and condensed matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed matter physics, where quantum relativistic phenomena, some of which are unobservable in high energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

The dispersion behavior of graphene oxide in different organic solvents has been investigated. As-prepared graphite oxide could be dispersed in N, N-dimethylformamide, N-methyl-2-pyrrolidone, tetrahydrofuran, and ethylene glycol. In all of these solvents, full exfoliation of the graphite oxide material into individual, single-layer graphene oxide sheets was achieved by sonication. The graphene oxide dispersions exhibited long-term stability and were made of sheets between a few hundred nanometers and a few micrometers large, similar to the case of graphene oxide dispersions in water. These results should facilitate the manipulation and processing of graphene-based materials for different applications.

Graphene is a monolayer of tightly packed carbon atoms that possesses many interesting properties and has numerous exciting applications. In this work, we report the antibacterial activity of two water-dispersible graphene derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets. Such graphene-based nanomaterials can effectively inhibit the growth of E. coli bacteria while showing minimal cytotoxicity. We have also demonstrated that macroscopic freestanding GO and rGO paper can be conveniently fabricated from their suspension via simple vacuum filtration. Given the superior antibacterial effect of GO and the fact that GO can be mass-produced and easily processed to make freestanding and flexible paper with low cost, we expect this new carbon nanomaterial may find important environmental and clinical applications.