Every year, more than 4 million people in Europe are affected by infections contracted during healthcare procedures, according to the European Centre for Disease Prevention and Control (ECDC). Many of these are bacterial infections that develop around medical devices and implants within the body, such as catheters, hip and knee prostheses, or dental implants. In the worst cases, implants need to be removed.
Such bacterial infections can cause great suffering for patients and can cost healthcare services huge amounts of time and money. Additionally, large amounts of antibiotics are currently used to treat and prevent such infections, costing more money and accelerating the development of antibiotic resistance.
“The purpose of our research is to develop antibacterial surfaces which can reduce the number of infections and subsequent need for antibiotics, and to which bacteria cannot develop resistance. We have now shown that tailored surfaces formed of a mixture of polyethylene and graphite nanoplatelets can kill 99.99 percent of bacteria which try to attach to the surface,” says Santosh Pandit, postdoctoral researcher in the research group of Professor Ivan Mijakovic at the Division of Systems Biology, Department of Biology and Biotechnology, Chalmers University of Technology.
Infections on implants are caused by bacteria that travel around in the body in fluids, such as blood, in search of a suitable surface. When they find one, they start to multiply and form a biofilm – a bacterial coating.
Previous studies from the Chalmers researchers showed how vertical flakes of graphene, placed on the surface of an implant, could form a protective coating, making it impossible for bacteria to attach – like spikes on buildings designed to prevent birds from nesting. The graphene flakes damage the cell membrane, killing the bacteria. But producing these graphene flakes is expensive and currently not feasible for large-scale production.
“But now, we have achieved the same outstanding antibacterial effects, but using relatively inexpensive graphite nanoplatelets, mixed with a very versatile polymer. The polymer, or plastic, is not inherently compatible with the graphite nanoplatelets, but with standard plastic manufacturing techniques, we succeeded in tailoring the microstructure of the material, with rather high filler loadings, to achieve the desired effect. And now it has great potential for a number of biomedical applications,” says Roland Kádár, Associate Professor at the Department of Industrial and Materials Science at Chalmers.
The nanoplatelets on the surface of the implants prevent bacterial infection but, crucially, without damaging healthy human cells. Human cells are around 25 times larger than bacteria, so while the graphite nanoplatelets slice apart and kill bacteria, they barely scratch a human cell.
“In addition to reducing patients’ suffering and the need for antibiotics, implants like these could lead to less requirement for subsequent work, since they could remain in the body for much longer than those used today,” says Pandit. “Our research could also contribute to reducing the enormous costs that such infections cause healthcare services worldwide.”