A method of forming a scaffold comprises the steps of: preparing a high internal phase emulsion (HIPE) comprising an aqueous solution of: proteins selected from the group consisting of collagen and mixtures of collagen and chitosan; and a cross-linking agent; by addition of an immiscible solvent to the solution to form the HIPE; reducing the temperature of the HIPE to solidify the HIPE; removing water and solvent by vaporisation at a temperature above the melting point of the solvent to form a porous structure; and before or after removal of solvent, causing cross-linking of the protein with the cross-linking agent to form a crosslinked scaffold structure.