Medical devices and methods of making the devices are described. In some embodiments, the methods include a method of manufacturing a device including a first layer and a second layer, the method including the steps of selecting a material for the second layer, the material having a viscosity value at a shear rate of about 1 s−1 or less and at a selected temperature; selecting a nanocomposite material for the first layer that has a viscosity within about 20% to about 125% of the viscosity value of the material for the second layer; and co-extruding the first and second layers.