Superhemophobic Surfaces Could Enhance Implant Biocompatibility

A new study describes how a specially grown titanium surface that is extremely repellent to blood could lower the risk of medical implant rejection.

Researchers at Colorado State University first analyzed variations of titanium surfaces, including different textures and chemistries, comparing them to define variations in platelet adhesion and activation. They found that only superhemophobic surfaces with a robust Cassie–Baxter state displayed significantly low platelet adhesion and activation. In this state, liquid does not completely wet the surface texture; instead, pockets of air remain trapped underneath the liquid droplet, introducing a composite liquid–air–solid interface.

The researchers achieved the Cassie–Baxter state in titanium surfaces by combining a surface chemistry with low solid surface energy and an appropriate texture created via fluorinated nanotubes. The result was a metastable Cassie–Baxter state that greatly reduced the solid–liquid interfacial area. In fact, the researchers found that the surface was so repellent that blood is deceived into accepting there is almost no foreign material present. The study was published on December 21, 2016, in Advanced Healthcare Materials.

“A material phobic to blood might seem counterintuitive, as often biomedical scientists use materials with affinity to blood to make them biologically compatible,” said senior author professor of mechanical engineering and biomedical engineering Arun Kota, PhD. “What we are doing is the exact opposite. We are taking a material that blood hates to come in contact with, in order to make it compatible with blood.”

“Over time, stents can form clots, obstructions, and lead to heart attacks or embolisms. The reason blood clots is because it finds cells in the blood to go to and attach,” said corresponding author Ketul Popat, PhD. “Normally, blood flows in vessels. If we can design materials where blood barely contacts the surface, there is virtually no chance of clotting, which is a coordinated set of events. Here, we're targeting the prevention of the first set of events.”