The researchers from Shanghai university said it had developed two water-based dispersible graphene derivatives can “effectively inhibit the growth of E.coli” that have minimal toxic effects on harming cells – so-called cytotoxicity.
Graphene is a monolayer of carbon atoms tightly-packed into a two-dimensional crystal. This nanomaterial possesses “very high material stiffness”, said Chunhai Fan et al in their study Graphene-based Antibacterial Paper published in the journal ACS Nano.
The research examined grapheme oxide (GO) and reduced grapheme oxide (rGO) nanosheets for their antibacterial properties and ease of fabrication.
Evaluating the interactions between GO and bacterial and mammalian cells, Chunhai’s team said their experiments demonstrated the “excellent antibacterial activity and minimal cytotoxicity of GO sheets”. They added that they found macroscopic antibacterial grapheme-based paper can be “conveniently fabricated with superior inhibition ability to bacteria growth”. Such properties suggest the technology could provide carbon nanomaterials that were green, cheap and highly effective.
The group tested the antibacterial properties of the GO sheets with E.coli DH5 cells via a luciferase-based ATP assay kit. After two hours incubation with the GO sheets of 20 µg/mL at 37C, the cell metabolic activity of the bacteria fell to around 70 per cent. With a GO concentration of 85 µg/mL, the activity of the E.coli cells fell to just 13 per cent – “suggesting a strong inhibition ability of GO nanosheets to E.coli,” said the researchers.
The rGO also exhibited high antibacterial effects – reducing metabolic E.coli DH5 cells to around 24 per cent on treatment with the materials at 85 µg/mL at 37C over the same time period. Colony counting showed less that 10 per cent survival for the E.coli cells, said the scientists.
But while the antibacterial properties of rGO were only slightly lower than GO, their cytotoxicity was found to be “significantly higher” The study said this might be due to “different surface changes and functional groups of GO and rGO nanosheet surfaces”.
Both the GO and rGO nanosheets were easily made into macroscopic, free-standing, robust and flexible paper” using a one-step vacuum filtration process. The study used airborne bacteria tests to measure antibacterial activity on the paper. An overnight incubation at 37C showed no cell growth on the GO paper and only “a limited number of E.coli colonies on the rGO paper”.
‘Given the superior antibacterial effect of GO nanosheets and the fact that GO nanosheets can be mass-produced and easily processed to make free-standing and flexible paper with low cost, we expect this new carbon nanomaterial could offer new opportunities fro the development of antibacterial materials,” concluded the researchers.
Graphene-based Antibacterial Paper by Wenbing Hu, Cheng Peng, Weijie Luo, Min Lv, Xiaoming Li, Di Li, Qing Huang and Chunhai Fan Published in ACS Nano. DOI: 10.1021/nn101097v