Proteins in blood can cling to the sides of the medical implants, building up over time and forming a blood clot. Often this requires invasive surgery to remove or replace the implant.
“Medical implants are constantly under pressure to perform in the human body. A heart valve is constantly under high pressure to pump blood, opening and closing half a billion times over 10 years,” said Dr Sina Naficy, who leads a research team developing heart valves that are more resistant to blood clots.
“The current average lifespan of existing heart valve implants is less than 10 years and there is always a risk of them degrading or complications occurring. By using Zwitterion coated materials, we aim to decrease the risk of blood clots and increase the lifespan of heart valves and other medical implants,” said Dr Naficy, from the University’s School of Chemical and Biomedical Engineering, Faculty of Engineering.
Zwitterions are molecules with positively and negatively charged groups, resulting in a neutral overall charge. They are very effective at forming bonds with water molecules, and are in human cells as part of the cell membrane. They create a thin layer of water and make sure blood and other proteins travel through the heart and other organs without sticking to other surfaces.
MORE FROM MEDICAL & HEALTHCARE
Dr Naficy’s team was inspired by the cell membrane and is currently working to mimic this so that they can design materials that could extend the lifespan of medical implants.
Currently the team has created a zwitterionic coating where, on areas of the material ‘painted’ with the coating only a few nanometres thick, it successfully created a layer and bubble of water. On material without the coating, it repelled and spread water beyond the material’s boundaries.
“We are currently exploring new formulations capable of being chemically attached to the surface of any type of implant [made from tissues, metals, or plastics/rubbers] with the aim of reducing their interactions with blood,” said Dr Sepehr Talebian from the School of Chemical and Biomedical Engineering.
One of the biggest obstacles scientists want to overcome is how many Zwitterions are required.
“There is great potential but what is the best way to use Zwitterions? What is the ideal thickness of the coating? What concentration should we use? We cannot just dip an artificial heart valve in the Zwitterionic substance without investigating the best conditions. Too much, and it could make the clotting worse, too little, and the risk of blood clots remains,” said Dr Talebian.
“We also need to investigate the best way to ‘anchor’ Zwitterions to the surface of a material, and the best environment for Zwitterions. This includes finding the best concentration of ‘salt’ in a solution with the Zwitterions. Too much salt makes Zwitterionic brushes clump together. We want them to spread evenly across surfaces.”
Discover the Legacy of Nevil Shute Norway, Engineer & Author
Unfortunately, On The Beach had the effect of increasing the fear of any nuclear power and has led to excessive controls on the UK nuclear industry.