Study for creation of water-soluble silk fibroin having high antioxidant and antibacterial activities by irradiation treatment

Silk fibroin at dry state and the solution of 3% were irradiated by Co-60 source at dose ranges of 0 - 1000 kGy and 0 - 50 kGy respectively at Hanoi Irradiation Centre. The results showed that antioxidant and antibacterial activities of fibroin were much improved by radiation treatment. The activities of the fibroin solution irradiated at low dose were higher than those of fibroin powder irradiated at high dose suggested that radiation treatment of fibroin in solution state was more effective than in dry state. Maximum value of DPPH radical scavenging activity was 70.4% for the solution of silk fibroin irradiated at 10 kGy. Silk fibroin solutions irradiated at doses higher than 10 kGy also exhibited rather high antibacterial activity against E. coli and S. aureus. In order to estimate the applicability of our irradiated fibroin, the silk fibroin solutions irradiated at 10 kGy were lyophilized to obtain a pure fibroin powder, then their bio-activities were compared with those of commercial silk fibroin (Proteines De Soie/ Zijdeproteine, Bioflore, Canada). Our fibroin powder revealed higher antioxidant and antibacterial activities. The amino acid compositions of our irradiated fibroin were also higher than that of the commercial product. Thus, the irradiated silk fibroin can be used for further application in cosmetic and other related fields. (author)