Graphene consists of a single, flat sheet of carbon arranged in a honeycombed lattice. Since the material was first created in 2004, its unique electronic and mechanical properties have amazed researchers who say that it could be used in a host of device applications – and even perhaps replace silicon as the electronic material of choice in the future.

Now, Chunhai Fan and colleagues have added another application to graphene's growing repertoire. The researchers have found that graphene derivatives, like graphene oxide and reduced graphene oxide, inhibit bacterial growth. This is an important finding, says Fan, because previous studies showed that graphene, and particularly graphene oxide, is biocompatible and that biological cells can grow well on graphene substrates. While other nanoparticles, like silver, are well known antibacterial materials, they are often cytotoxic.

The researchers made graphene paper by first synthesizing graphene oxide and reduced graphene oxide in water. This solution was then filtered through paper under vacuum. Freestanding graphene oxide and reduced graphene oxide sheets were then peeled off from the filter paper.

E.Coli destroyed
Transmission electron microscopy showed that the cell membranes of E. Coli bacteria placed on the graphene sheets were severely destroyed. According to the researchers, this occurs because graphene enters the endosome of the cell's cytoplasm, pushing it out of the cell. Almost 99% of the cells were destroyed after just two hours in contact with a 85 g/mL solution of graphene oxide at 37 °C. In contrast, the nanosheets were not toxic to mammalian cells under the same conditions.

The team is now further studying why and how graphene oxide is antibacterial. "Ultimately we wish to develop new antibacterial materials from graphene that could be directly applied onto skin to aid in wound healing," Fan told "However, we are aware that it is still a challenge to mass produce graphene nanomaterials, and particularly to fabricate large-scale graphene paper."

The results were published in ACS Nano.