A deformable implantable medical device such as a stent comprising metallic, polymer and/or composite substrate having a columnar structured plasma polymer surface capable of binding functional biological molecules. The polymer surface can be bound to the substrate through a mixed or graded interface formed by a co-deposition process where a substrate material is deposited with carbon containing species while gradually reducing the substrate material proportion and increasing the carbon containing species proportion. The device is able to undergo deformation without substantial delamination of the plasma polymer surface.
