ABSTRACT: Polymers and other materials that are used in contact with biological fluids such as blood are prone to protein adsorption and cell interactions. A protein layer quickly forms at the surface of the material and can influence the subsequent adhesion of platelets, leukocytes, other cells and microbes. For medical devices this can lead to numerous complications including coagulation, thrombosis (blood clotting) and infection, among others.
Both chemical and biological strategies to modify the surface of biomaterials can be implemented to better control these interfacial processes and improve device design. In previous work, polyurethane was grafted with polyethylene oxide (PEO), a polymer known for its ability to resist protein adsorption. Various molecular weights and end groups of PEO were used to attach an antithrombin-heparin complex (ATH) to provide an active anticoagulant function. Surface characterization techniques confirmed modifications and biological methods demonstrated improved activity compared to heparinized materials commonly used in commercially available devices. These results provide an indication of the ability to obtain enhanced anticoagulant activity and show promise for use with devices such as catheters, stents and vascular grafts. In addition the initial passive modification steps have been applied to microfluidic device design, resulting in reduced protein adsorption and demonstrating potential for future development.
Further investigations of base polymers in addition to polyurethane are of interest, for example silicones, polyethylene terephthalate and membrane materials including polyether sulfones. Along with PEO of varying architectures, other polymers known for their resistance to protein adsorption will be compared by grafting both to and from the surface of the base polymers. By using surface patterning techniques and combining these passive modification strategies with an array of active molecules there is great potential to improve the design of blood contacting devices and tissue engineering scaffolds. Additionally, these methods can be applied to studies targeting microbial adhesion in both medical device and industrial applications.
Biosketch: Dr. Kyla Sask obtained her B.Sc. in Chemical Engineering from Queen’s University in 2006 and her Ph.D from the School of Biomedical Engineering at McMaster University in 2012. Her Ph.D research was supervised by Dr. John Brash from the Department of Chemical Engineering and Dr. Anthony Chan from the Department of Pediatrics, and focused on the development of antithrombogenic biomaterials. Dr. Sask spent 2 years as an Associate Research Engineer at Interface Biologics Inc., an early commercial stage company that develops transformative polymer technology. During this position she was part of the team developing Endexo™, a platform technology utilized for its antithrombogenic properties in various medical device applications. Her research interests are in the areas of protein adsorption and microbial adhesion to biomaterials, surface modification and characterization, and blood contacting medical devices.