To investigate the structure of silk and its degradation properties,we have monitored the structure of silk using scanning electron microscopy and frozen sections.Raw silk and degummed raw silk were immersed in four types of degradation solutions for 156 d to observe their degradation properties.The subcutaneous implants in rats were removed after 7,14,56,84,129 and 145 d for frozen sectioning and subsequent staining with hematoxylin eosin(H.E),DAPI,beta-actin and collagen I immunofluorescence staining.The in vitro weight loss ratio of raw silk and degummed raw silk in water,PBS,DMEM and DMEM containing 10%FBS(F-DMEM)were,respectively,14%/11%,12.5%/12.9%,11.1%/14.3%,8.8%/11.6%.Silk began to degrade after 7 days subcutaneous implantation and after 145 d non-degraded silk was still observed.These findings suggest the immunogenicity of fibroin and sericin had no essential difference.In the process of in vitro degradation of silk,the role of enzymes is not significant.The in vivo degradation of silk is related to phagocytotic activity and fibroblasts may be involved in this process to secrete collagen.This study also shows the developing process of cocoons and raw silk.
Silk Fibroin Structure Degradation Bombyx mori L
Bin Liu Yu-wei Song Li Jin Zhi-jian Wang De-yong Pu Shao-qiang Lin Chan Zhou Hua-jian You Yan Ma Jin-min Li Li Yang K.L.Paul Sung Yao-guang Zhang
Key Laboratory of Freshwater Fish Reproduction and Development(Southwest University),Ministry of Edu Core Laboratory of the First Affiliated Hospital of Jinan University,Guangzhou 510630,China Chongqing Academy of Animal Science,Chongqing 400015,China Department of Obstetrics,the Ninth People”s Hospital of Chongqing,400700,China College of Bioengineering,Chongqing University,Chongqing 400044,China College of Bioengineering,Chongqing University,Chongqing 400044,China;Department of Orthopaedics,Uni