A longstanding problem in the use of implantable biomedical devices is their incompatibility with human tissues and blood. Contact between blood and the surfaces of currently-approved devices such as stents, heart valves, catheters, and dialysis tubing can lead to inflammation and thrombosis. Thrombosis, or the formation of blood clots, can obstruct flow in blood vessels, and can also lead to heart attacks and strokes. In the quest for better biocompatible materials, Matt Kipper and his team are turning to complex structured and multifunctional surfaces created by nature for inspiration.
Kipper’s research, funded by the National Science Foundation, applies the concept of strategic biomimicry to create structural features in new biomaterials that are similar to those found in blood vessels throughout the body. Their recent research recreates features of the glycocalyx, a hair-like coating lining the walls of blood vessels, by forming nanoparticles having a “brush-like” structure and then attaching them to surfaces. Kipper and CSU collaborators Diego Krapf and Melissa Reynolds have shown that when blood proteins contact surfaces with these glycocalyx mimics, the proteins are prevented from forming the fiber networks that stabilize blood clots. Kipper and Reynolds are also collaborating with CSU colleague Ketul Popat to show that these glycocalyx mimics can be designed to reduce or eliminate adhesion and activation of blood platelets, which are critical in blood clot or thrombus formation.
Fluorescently labeled fibrin network forms on a control surface (red fibers, left). Experimental biomimetic surface prevents fibrin network formation (right). Red spots indicate fibrin adsorption but no fibers or fiber network forming. This surface could prevent blood clots by preventing these fibers from forming on the surface.
ENGINEERING THE WORLD’S STRONGEST BIOMATERIAL
Kipper is also the co-PI of a $1.7 million grant recently awarded to CSU from the Defense Advanced Research Projects Agency (DARPA), aimed at developing a biomanufacturing process for sporopollenin, the biopolymer coating on plant pollen. The extreme durability of sporopollenin has generated interest in developing ways to mass produce it for use as a protective coating, including for large-scale applications such as ships, bridges, and buildings. Kipper’s co-PIs Mauricio Antunes, June Medford, and Kevin Morey from the CSU biology department will genetically modify a host plant to produce sporopollenin-like materials with desired properties. Kipper will apply advanced techniques in high-resolution microscopy and spectroscopy to characterize the structures and functions of the new biopolymers.
ABOUT THE KIPPER GROUP
Matt Kipper is a professor of chemical and biological engineering at Colorado State University, and holds joint appointments in the School of Biomedical Engineering and the School of Advanced Materials Discovery. He earned his B.S. and Ph.D. in chemical engineering from Iowa State University in 2000 and 2004, respectively. While at Iowa State, Kipper worked to develop a polymer-based system for single-dose vaccine delivery.
Before joining CSU in 2006, Kipper worked as a guest researcher for two years at the National Institute of Standards and Technology (NIST) and the National Institutes of Health (NIH) with a joint NIST/NIH fellowship from the National Research Council. There, he developed experimental and mathematical modeling techniques to study the migration of connective tissue cells on biomaterials with gradients of adhesion ligand peptides, applied to the design of new materials for wound healing and tissue engineering applications.
At CSU, Kipper and his team members focus on the development and characterization of polymeric materials for biomedical applications. Of particular interest are the polyelectrolyte properties of biologically derived polysaccharides, and how these properties can be exploited to tailor the nanostructure of biomaterials. He is also studying interactions of proteins and cells with these nanostructured materials to optimize their surface properties for particular biomedical applications. Kipper received the Abell Outstanding Early-Career Faculty Award in 2011 and the College of Engineering Faculty Achievement Award in 2015.
“Biology presents us with a vast repertoire of tissues and materials with unique and amazing functions and properties. The inside surfaces of healthy blood vessels are the only known surfaces which are completely compatible for long-term exposure to flowing whole blood. We look to these and many other biologically-derived materials for inspiration and design principles for the next generation of high-performance materials.”
Make the connection
The Colorado State University School of Biomedical Engineering (SBME) provides transdisciplinary education, research, and practical experiences throughout a full range of degree programs. The unique structure of the School involves four colleges, 14 departments, and over 70 faculty.
Research interests of the faculty involved in the Medical Devices and Therapeutics theme in SBME include biomedical image and signal processing, cardiovascular mechanics, equine orthopedics, and polymeric biomaterials.