IN-SITU SELF-ASSEMBLING PROTEIN POLYMER GEL SYSTEMS FOR ADMINISTRATION, DELIVERY, AND RELEASE OF DRUGS

Sequential block copolymers consisting of tandem repetition of amino a cids have been constructed and genetically produced based on the natur al repeating structures of silk and elastin protein. Combinations of s ilklike and elastinlike amino acid sequence blocks in a high molecular weight protein polymer are used to confer properties similar to those observed with hard block and soft block segmented polyurethanes. A ce rtain subset of these silk-elastinlike protein compositions, termed Pr oLastins, will undergo an irreversible solution to gel transition in p hysiological, aqueous solution. The transition occurs over time and ca n be controlled by temperature, solution conditions, and additives whi ch either prevent or promote hydrogen bond-mediated chain crystallizat ion. The process involves no covalent crosslinking. Characterization o f the gelling properties of various ProLastin compositions and their a bility to release compounds which are incorporated directly into the g els are presented. (C) 1998 Elsevier Science B.V.