An implantable repair device for the repair, augmentation or replacement of tissue, the device comprising silk fibroin and wherein the device comprises a smooth surface and a porous surface. The smooth surface is defined as a surface having a measured Sa value of less than approximately 0.1µm when using Atomic Force Microscopy (using, for example, the Bruker Dimension Icon System), when samples of the repair device are fully hydrated by imaging through fluid in peak force tapping mode. Also covered is a method of preparing an implantable repair device or a portion or layer of such a device for the repair, augmentation or replacement of tissues, the method comprising the steps of: preparing a gel from a fibroin solution in a mould； preparing a material by subjecting the gel to one or more steps of freezing and thawing the gel； and creating at least a porous surface on said device, wherein in preparing the gel from the fibroin solution, a portion of the mould is adapted to provide at least one smooth surface.
