Concentrated aqueous silk fibroin solution and use thereof

Abstract

The present invention provides for concentrated aqueous silk fibroin solutions and an all-aqueous mode for preparation of concentrated aqueous fibroin solutions that avoids the use of organic solvents, direct additives, or harsh chemicals. The invention further provides for the use of these solutions in production of materials, e.g., fibers, films, foams, meshes, scaffolds and hydrogels.

We claim: 
     
         1 - 58 . (canceled) 
     
     
         59 . An aqueous silk fibroin solution having a fibroin concentration of at least 4 wt %, wherein said solution is fee of organic solvents, and wherein the silk fibroin is obtained from: a silkworm silk obtained from  Bombyx mori  or a solution containing a genetically engineered silk. 
     
     
         60 . The aqueous silk fibroin solution of  claim 59 , wherein the fibroin concentration is between 4 wt % to 20 wt %. 
     
     
         61 . The aqueous silk fibroin solution of  claim 59 , the aqueous silk fibroin solution consisting of the silk fibroin and water. 
     
     
         62 . The aqueous silk fibroin solution of  claim 59 , the aqueous silk fibroin solution further comprising an additive. 
     
     
         63 . A method comprising the steps of:
 (a) preparing a silk fibroin solution comprising silk fibroin in an aqueous salt solution; and   (b) dialyzing said solution against a hygroscopic polymer to result in an aqueous silk fibroin solution of at least 4 wt % of fibroin.   
     
     
         64 . The method of  claim 63 , further comprising the step of casting the aqueous silk fibroin solution to form a film. 
     
     
         65 . The method of  claim 64 , wherein the casting includes air-drying. 
     
     
         66 . The method of  claim 63 , wherein the dialyzing results in the aqueous silk fibroin solution having at least 10 wt % of fibroin. 
     
     
         67 . A silk fibroin composition having a fibroin concentration of at least 4% silk fibroin but not more than 33% silk fibroin, wherein said composition is free of alcohol. 
     
     
         68 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition comprises between about 10% and about 30% silk fibroin. 
     
     
         69 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition is a film. 
     
     
         70 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition is frozen. 
     
     
         71 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition is lyophilized or freeze-dried. 
     
     
         72 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition is air-dried. 
     
     
         73 . The silk fibroin composition of  claim 67 , wherein the silk fibroin composition is a solid. 
     
     
         74 . The silk fibroin composition of  claim 67 , the silk fibroin composition further comprising an additive. 
     
     
         75 . A method comprising the steps of:
 (a) boiling  Bombyx mori  cocoons in an aqueous solution;   (b) preparing a silk fibroin salt solution comprising silk fibroin from the  Bombyx mori  cocoons in an aqueous salt solution;   (c) removing salt from said aqueous salt solution to result in an aqueous silk fibroin solution of at least 4 wt % of fibroin.   
     
     
         76 . The method of  claim 75 , further comprising the step of casting the aqueous silk fibroin solution to form a film. 
     
     
         77 . The method of  claim 76 , wherein the casting includes air-drying. 
     
     
         78 . The method of  claim 75 , wherein the removing salt results in an aqueous silk fibroin solution having at least 10 wt % of fibroin.