Biodegradable biopolymers, method for their preparation and functional materials constituted by these biopolymers

Abstract

A biodegradable biopolymer material consists of silk fibroin from domesticated silkworm; silk fibroin from wild silkworm; a composite material comprising silk fibroin from domesticated silkworm and silk fibroin from wild silkworm; or a composite material comprising either silk fibroin from domesticated silkworm or silk fibroin from wild silkworm and at least one secondary substance selected from the group consisting of cellulose, chitin, chitosan, chitosan derivatives, keratin from wool and polyvinyl alcohol. The material may be prepared by, for instance, casting an aqueous solution of domesticated silkworm silk fibroin on the surface of a substrate and then cast drying the applied solution. The biodegradable biopolymer material is effectively used as, for instance, a metal ion-adsorbing material, a sustained release substrate for a useful substance such as a medicine, a biological cell-growth substrate and a biodegradable water-absorbing material.

1 . A method for the preparation of a biodegradable biopolymer material comprising the steps of applying, onto the surface of a substrate, an aqueous solution of silk fibroin from domesticated silkworm, an aqueous solution of silk fibroin from wild silkworm, an aqueous mixed solution containing an aqueous solution of silk fibroin from domesticated silkworm and an aqueous solution of silk fibroin from wild silkworm or an aqueous mixed solution containing either an aqueous solution of silk fibroin from domesticated silkworm or an aqueous solution of silk fibroin from wild silkworm and an aqueous solution of at least one secondary substance selected from the group consisting of cellulose, chitin, chitosan, chitosan derivatives, keratin from wool and polyvinyl alcohol and then cast drying the applied solution to form a membrane-like biodegradable biopolymer material, wherein if using the mixed aqueous solution, the aqueous solutions as the constituents of the mixed solution are uniformly admixed together by stirring them such that they do not undergo any gelation, precipitation and/or coagulation reaction to thus prepare the aqueous mixed solution. 
     
     
         2 . The method as set forth in  claim 1 , wherein the concentrations of the aqueous solution of the silk fibroin from domesticated silkworm, the aqueous solution of the silk fibroin from wild silkworm and the aqueous solution of the secondary substance used in the preparation of the mixed aqueous solution range from 0.1 to 5% w/v. respectively.