Frictional properties of poly(MPC-co-BMA) phospholipid polymer for catheter applications

A fundamental understanding of surface properties of the biomaterials at a nanometer scale should be generated in order to understand cellular responses of the tissue to biomaterials thereby minimizing or eliminating tissue trauma at a macrometer scale. In this study poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) ([poly(MPC-co-BMA]) was evaluated as a potential coating material for vascular applications to provide smooth catheterization using atomic force microscopy (AFM) techniques.A uniform coating of [poly(MPC-co-BMA] equivalent to a thickness of 2.5 microm on a polyurethane (PU) catheter material was provided using dip casting technique. Using a contact mode AFM, no significant difference in surface roughness (R(a)) and frictional force (f) between uncoated (R(a)=10.2+/-1.9 nm, f=0.907+/-0.02) and coated (R(a)=11.7+/-1.8 nm, f=0.930+/-0.06) surfaces was observed under dry conditions. However, under wet conditions the R(a) of the coated surface (3.4+/-1.0 nm) was significantly lower than uncoated PU surface (9.0+/-1.8 nm). The coating on PU substrate offered the least frictional resistance (f=0.004+/-0.001) illustrating enhanced boundary lubrication capability due to hydration of phosphorylcholine polymer as compared to a significantly higher f for uncoated PU (0.017+/-0.007) surfaces. These tribological and chemical characteristics of the [poly(MPC-co-BMA)] coating could increase the overall efficacy of PU for clinical applications.