Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties

Abstract

In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibro in structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 ◦C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS–PAGE),respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS–PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 ◦C.

Enhanced osteoinductivity and osteoconductivity through hydroxyapatite coating of silk‐based tissue‐engineered ligament scaffold

“…Knitted scaffolds of 2 cm × 4 cm dimension were fabricated using raw silk fibers ( Bombyx mori ) with 14 needles on a knitting machine (Silver‐reed SK270, Suzhou, China). The knitted scaffolds were degummed to remove sericin coat from silk fibroins using a modified alkaline degumming technique involving shaking the scaffolds in a solution of 0.25% (w/v) Na 2 CO 3 and 0.25% (w/v) sodium dodecyl sulfate at 98–100°C for 90 min 21, 22. A silk fibroin solution was prepared by similarly degumming raw silk fibers and dissolving the degummed silk in a ternary solvent system of CaCl 2 /CH 3 CH 2 OH/H 2 O (1:2:8 molar ratio) at 69°C with continuous stirring.…”

Use of a Silk Fibroin-Chitosan Scaffold to Construct a Tissue-Engineered Corneal Stroma

“…The silk elaboration and synthesis process was performed as described by Teh et al [2010] and Altman et al [2009]. In brief, the sericin coating was removed via degumming.…”

Differentiation of MSC and annulus fibrosus cells on genetically engineered silk fleece‐membrane‐composites enriched for GDF‐6 or TGF‐β3

“…In short, B. mori larvae were cultured in sterile sericulture and infected with baculovirus causing incorporation of desired growth factor into silk fibroin, see Figure modified with permission according to Kato et al Silk was directly harvested from silk glands to reduce contamination with sericin to a minimum. This was important in the production, as sericin is known to cause allergic reaction in the human body . For generation of baculoviral constructs first the coding sequence of the B. mori fibroin light chain protein (FLC) including its signal sequence (NM_001044023.1) was synthesized by MWG (Eurofins MWG Operon, Ebersberg, Germany) and cloned into the pFastBac/NT‐TOPO vector system (Invitrogen, Thermo Fisher Scientific Inc., Basel, Switzerland).…”