Effects of gamma radiation on biodegradation of Bombyx mori silk fibroin

Silkworm silks have been utilized in biomedicine for centuries. The biocompatibility of silks has been a problem for a long time due to the residual sericin on silk fibroin. Even when the sericin has been removed, this problem has still been found in some patients. This might be a result of the slow biodegradation rate of silk fibroin. Therefore, an attempt to reduce the biodegradation period of silk fibroin through gamma radiation was studied. Silks from the native Thai silkworm,Bombyx mori var. Nangnoi Sisaket-1, were irradiated with various doses before in-vitro biodegradation testing. The results showed that the biodegradation of silk fibroin increased with increasing irradiation intensity. This could be attributed to the weakness of peptide bonding in fibroinʹs polypeptides, reduction of β-sheet structure in the silk fibroin which was transformed to random coil structure, increase of erosion and cleft on fibroin fibers, and release of low-molecular-weight proteins in degradation products.