biocompatible polymeric materials capable of providing in situ release of nitric oxide included diazeniumdiolated fumed silica as a filler in a multilayer polymer structure to release no upon contact with water . the blood - contacting polymer surface is preferably multi - layered so that the no - releasing layer , containing the diazeniumdiolated fumed silica , is shielded from blood contact by one or more top coats . when in contact with blood , the no released at the surface of the polymer prevents platelet activation and adhesion to the surface , thereby reducing platelet consumption , risk of thrombus formation and other clinical complications associated with interactions between blood and foreign materials .