a plasma - activated coating process covalently binds enzymes in their bioactive state , has low thrombogenicity and can be robustly applied to medical devices , resisting delamination when deployed in vivo . applying this process to attachment of proteins such as enzymes that inhibit thrombosis and anticoagulants such as heparin or heparin fragments , one can produce medical devices and other materials for use in vascular applications having a number of benefits including covalent attachment , not requiring intermediate linkers or chemistry ; substrate independent works on polymers , metals , ceramics , 3d shapes like stents , valves , etc . ; bioactivity is retained ; surface may retain greater bioactivity over time in vivo ; simultaneously supports endothelialisation ; can be stored for long periods , following freeze drying , and retains effectiveness when rehydrated and ; surface is able to bind many fibrinolytic enzymes such as streptokinase , urokinase , tpa , plasmin ).