Antifouling Zwitterionic Polymer Coatings for Blood-Bearing Medical Devices

Blood-bearing medical devices are essential for the delivery of critical care medicine and are often required to function for weeks to months. However, thrombus formation on their surfaces can lead to reduced device function and failure and expose patients to systemic thrombosis risks. While clinical anticoagulants reduce device related thrombosis, they also increase patient bleeding risk. The root cause of device thrombosis and inflammation is protein adsorption on the biomaterial surfaces of these devices. Protein adsorption activates the coagulation cascade and complement, and this, in turn, activates platelets and white blood cells. Surface modifications with zwitterionic polymers are particularly effective at reducing protein adsorption as well as conformational changes in proteins due to their hydrophilicity. Multiple coating strategies have been developed using carboxybetaine (CB), sulfobetaine (SB), and 2-methacryloyloxyethyl phosphorylcholine (MPC) zwitterionic polymers applied to the metals and hydrophobic polymers that make up the bulk of blood-bearing medical devices. These coatings have been highly successful at creating large reductions in protein adsorption and platelet adhesion during studies on the order of hours on flat surfaces and at reducing thrombus formation for up to a few days in full medical devices. Future work needs to focus on their ability to limit inflammation, particularly during hemodialysis, and in providing anticoagulation on the order of weeks, particularly in artificial lungs.