This invention related to a tissue-
adhesive sheet comprising a homogeneous, preformed and cross-linked matrix formed from one or more polymers, and having at least one surface that, in use, is exposed, at least one of said one or more polymers being a
synthetic polymer and having appendant functional groups of a first form, cross-linking of said matrix being via a proportion of said functional groups of the first form, and the remainder of said functional groups of the first form being free. The sheet is particularly useful as a tissue
adhesive and
sealant, and is intended for topical application to internal and external surfaces of the body for therapeutic reasons. The invention further relates to sheets comprising a
scaffold material, three-dimensional articles formed from similar material to that of the sheet and to implantable medical devices coated with such material.