Abstract: A wound treatment device comprising a water-impermeable envelope having at least one aperture. The envelope contains a therapeutic substance. The at least one aperture in the envelope is blocked by a material that breaks down in the presence of one or more active components of wound fluid thereby permitting the therapeutic substance to contact the wound fluid. Preferably, the aperture is blocked by a material that is a substrate for an enzyme present in would fluid, such as a protease.

Abstract: The invention provides a method of preparing an antimicrobial sponge material for medicinal use, comprising the steps of: treating an anionic polysaccharide with a solution of a silver salt to produce a complex of the anionic polysaccharide with silver; dispersing said complex in aqueous ascorbic acid to form an acidified dispersion, followed by freeze-drying or solvent-drying the dispersion to form the sponge material. Also provided is a photostabilized antimicrobial sponge material comprising an anionic polysaccharide complexed with silver (I) ions, wherein the sponge further comprises ascorbic acid, and the sponge has a substantially white colour that is substantially stable against discoloration on exposure to light. Also provided are wound dressings comprising such materials, and the use of such materials in medicine.