Researchers at the Catholic University of the Sacred Heart and the Institute for Complex Systems in Rome studied how the size and concentration of graphene-oxide sheets affects its antimicrobial capabilities. They found that GO was extremely effective against bacteria, even in low concentrations and sizes, which could mean that it can be used as a coating material for medical instruments and devices to reduce infections, as well as reducing antibiotic use and antibiotic resistance.
The team examined the effect of GO on three bacteria: Staphylococcus aureus and Enterococcus faecalis, both of which cause various opportunistic and hospital-acquired infections, and Escherichia coli, which can cause severe food poisoning. They found that 200 nm sheets of graphene oxide in a water solution killed around 90% of S. aureus and E. faecalis, and around 50% of E. coli in less than two hours. Graphene oxide was effective against bacteria, even at concentrations below 10 μg/ml.
There are three mechanisms to the material's antibacterial properties: GO sheets can cut bacterial membranes acting as a nano-knife, wrap the bacteria as a blanket stopping their growth, or oxidise bacterial cellular components. The team also found that graphene oxide was effective against the fungus Candida albicans, which causes opportunistic fungal infections, with a similar efficacy as found with E. coli.
The researchers also point out that graphene oxide can be mixed with biocompatible polymers to make an antibacterial coating suitable for medical equipment susceptible to bacterial colonization, such as catheters. Surgical tools coated with the material, for example, could kill bacteria. This could reduce the need for antibiotics, decrease post-operative infections and cut recovery times.
The team's research was part of an EU-funded project called VANGUARD, which aims to test the feasibility of using graphene-oxide scaffolds to help repair and regenerate damaged tissue and organs.
While the results of this study are interesting and could provide the basis for a novel preventative agent, there is still a long way to go to show that this can be turned into medical components that are both safe and efficient. The team now plans to test the effect of graphene oxide on other pathogens, such as antibiotic-resistant bacteria, like Methicillin-resistant S. aureus (MRSA), viruses, and other fungi.
In March 2015, Scientists at the Natural Science Foundation and the Hospital-Public Cross-Link Project of Shanghai Jiao Tong University discovered that graphene oxide might be helpful in eliminating antibiotic-resistant bacteria that causes tooth decay and gum disease. In July 2013, scientists demonstrated that graphene can kill bacteria by slicing through their membranes and pulling out their phospholipids, and may be used in the future as an antimicrobial material for everyday use, applied directly to wounds.