(Credit: James Weaver, Harvard’s Wyss Institute)
Close-up
This Scanning Electron Microscope (SEM) image shows how red blood cells coagulate to form a blood clot, which is a common and life-threatening risk associated with the use of implanted medical devices.
A new coating for implantable medical devices has been developed using FDA–approved materials, which are inspired by the slippery surface of the carnivorous pitcher plant.
A team of Harvard scientists have developed the surface coating for medical devices, which uses materials already approved by the FDA. The coating repelled blood from more than 20 medically relevant substrates the team tested — made of plastic to glass and metal — and also suppressed biofilm formation in a study reported in Nature Biotechnology.
The team implanted medical–grade tubing and catheters coated with the material in large blood vessels in pigs, and it prevented blood from clotting for at least eight hours without the use of blood thinners such as heparin. Heparin is known for causing potentially lethal side–effects like excessive bleeding but is often a necessary evil in medical treatments where clotting is a risk.
"Devising a way to prevent blood clotting without using anticoagulants is one of the holy grails in medicine," said Don Ingber, M.D., Ph.D., Founding Director of Harvard's Wyss Institute for Biologically Inspired Engineering and senior author of the study. Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children's Hospital, as well as professor of bioengineering at Harvard School of Engineering and Applied Sciences (SEAS).
The idea for the coating evolved from SLIPS, a pioneering surface technology developed by coauthor Joanna Aizenberg, Ph.D., who is a Wyss Institute Core Faculty member and the Amy Smith Berylson Professor of Materials Science at Harvard SEAS. SLIPS stands for Slippery Liquid–Infused Porous Surfaces. Inspired by the slippery surface of the carnivorous pitcher plant, which enables the plant to capture insects, SLIPS repels nearly any material it contacts. The liquid layer on the surface provides a barrier to everything from ice to crude oil and blood.
"Traditional SLIPS uses porous, textured surface substrates to immobilise the liquid layer whereas medical surfaces are mostly flat and smooth — so we further adapted our approach by capitalizing on the natural roughness of chemically modified surfaces of medical devices," said Aizenberg, who leads the Wyss Institute's Adaptive Materials platform. "This is yet another incarnation of the highly customisable SLIPS platform that can be designed to create slippery, non–adhesive surfaces on any material."