The human body often rejects foreign objects introduced. This mechanism is designed to protect the body from damage, but is very problematic for medical devices implanted to help a patient. When a medical implant such as a stent or catheter is rejected by the body, blood platelets adhere to the device, forming a clot that encapsulates it. Those clots can lead to heart attacks, embolisms or infections. The current less than ideal solution, is to put patients on blood-thinning medications for the rest of their lives.
Engineers at Colorado State University, Dr Arun Kota and Ketul Popat, have developed blood repellent titanium that could be used to make the implants.
In a previous edition of the Crucible, we talked about superhydrophobic materials, making water form droplets on their surface. A blood repellent material is therefore superhaemophobic.
An image of a fluorinated nanotubes surface texture
The idea is that the blood does not meet the surface of the titanium and instead comes into contact with a layer of trapped air. As there is very little contact made, there is a greatly decreased chance of blood clots forming, and starting the chain of events that leads to more serious medical problems. The surface texture and chemistry of fluorinated nanotubes was found to produce the lowest level contact.
They produced this surface by taking a piece of titanium and growing the nanotubes using anodisation. The super liquid repelling surface is achieved with this type of texture and low-surface-energy fluorination chemistry. The chemistry part of the process used silanisation (covering the surface with a specific type of molecule).
One problem that the scientists need to watch out for is making sure the surface is not too flaky.
So far, tests have been made by simply using blood droplets sitting still on the surface. The next phase of testing will need the blood to flow dynamically over the surface, in order to mimic the flow of blood around the body. This would be followed by testing in an animal model. The scientists predict that it will be at lest 4-5 years before we see implants made from this blood repellent material.
A paper on their research was recently published in the journal Advanced Health Care Materials.
Source: Colorado State University
