“We did not actually plan this, but that is just how science works sometimes: you start researching one thing and end up somewhere else,” says ETH Professor Dimos Poulikakos. Together with scientists from his group and from the National University of Singapore, they developed and tested various superhydrophobic materials – which are, like Teflon, extremely good at repelling liquids such as water and blood. The goal was to find coatings for devices that come into contact with blood, for example heart-lung machines or artificial heart devices.

One of the materials tested demonstrated some unexpected properties: not only did it repel blood, but it also aided the clotting process. Although this made the material unsuitable for use as a coating for blood pumps and related devices, the researchers quickly realised that it would work ideally as a bandage.

Repelling blood and achieving fast clotting are two different properties that are both beneficial in bandages: blood-repellent bandages do not get soaked with blood and do not adhere to the wound, so they can be later removed easily, avoiding secondary bleeding. Substances and materials that promote clotting, on the other hand, are used in medicine to stop bleeding as quickly as possible. However, to date, no materials that simultaneously repel blood and also promote clotting have been available – this is the first time that scientists have managed to combine both these properties in one material.

Antibacterial effect

The researchers took a conventional cotton gauze and coated it with their new material – a mix of silicone and carbon nanofibres. They were able to show in laboratory tests that blood in contact with the coated gauze clotted in only a few minutes. Exactly why the new material triggers blood clotting is still unclear and requires further research, but the team suspects that it is due to the interaction with the carbon nanofibres.