title: Silk structure and degradation.
abstract: 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 and 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 d 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 the enzyme 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.
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Yu-wei
authors.initials: YW
authors.lastname: Song
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Li
authors.initials: L
authors.lastname: Jin
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Zhi-jian
authors.initials: ZJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: De-yong
authors.initials: DY
authors.lastname: Pu
authors.affiliation: Core Laboratory of the First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Shao-qiang
authors.initials: SQ
authors.lastname: Lin
authors.affiliation: Chongqing Academy of Animal Science, Chongqing 400015, China.
authors.forename: Chan
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Hua-jian
authors.initials: HJ
authors.lastname: You
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Obstetrics, the Ninth People's Hospital of Chongqing, 400700, China.
authors.forename: Jin-min
authors.initials: JM
authors.lastname: Li
authors.affiliation: College of Bioengineering, Chongqing University, Chongqing 400044, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: College of Bioengineering, Chongqing University, Chongqing 400044, China; Department of Orthopaedics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA; Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA.
authors.forename: K L Paul
authors.initials: KL
authors.lastname: Sung
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Southwest University), Ministry of Education, Chongqing 400715, China; School of Life Science, Southwest University, Chongqing 400715, China. Electronic address: zhangyg@swu.edu.cn.
authors.forename: Yao-guang
authors.initials: YG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D012831:Bombyx / Q000378:metabolism*; D005260:Female; D005349:Fibroins / Q000378:metabolism*; D019476:Insect Proteins / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D019736:Prostheses and Implants; D059748:Proteolysis; D017207:Rats, Sprague-Dawley; D047030:Sericins / Q000378:metabolism*; D047011:Silk / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D040521:Subcutaneous Tissue / Q000378:metabolism / Q000601:surgery; D013997:Time Factors
chemical_list: D019476:Insect Proteins; D047030:Sericins; D047011:Silk; D005349:Fibroins
keywords: Bombyx mori L.; Degradation; Fibroin; Silk; Structure