Silk-based capsules
A hard or soft capsule is disclosed comprising a shell and a fill material, wherein the shell comprises an interpenetrating network comprising a silk polymer and a film-forming natural polymer. A method of making a hard or soft capsule is also disclosed, comprising dissolving a silk protein in a solvent system to form a solubilized silk protein solution; mixing the solubilized silk protein solution with a film-forming natural polymer to form a homogenous shell material; and encapsulating a fill material with the homogenous shell material.
1. A soft capsule shell consisting essentially of:
0.28% silk fibroin by weight of the capsule shell,
41.8% gelatin by weight of the capsule shell,
9.5% glycerol by weight of the capsule shell,
11.4% sorbitol by weight of the capsule shell, and
37.0% water by weight of the capsule shell
wherein the soft capsule shell provides extended release of a fill material at pH 7.2, and wherein the silk fibroin has an average molecular weight ranging from 50 kDa to 450 kDa.
2. The capsule shell of claim 1 , wherein the silk fibroin has an average molecular weight of 100 kDa.
3. The capsule shell of claim 1 , wherein the silk fibroin comprises Bombyx mori silk fibroin.
4. A method for manufacturing a soft capsule comprising the shell of claim 1 , the method comprising:
combining silk fibroin, gelatin, glycerol, sorbitol and water to form a homogenous shell material;
providing a fill material comprising one or more pharmaceutical agents; and
producing a soft capsule using rotary die encapsulation.
5. A soft capsule manufactured from the method of claim 4 .