Article ID Journal Published Year Pages File Type
5512372 International Journal of Biological Macromolecules 2017 31 Pages PDF
Abstract
We investigate the linear and nonlinear viscoelastic properties as well as the reversibility of strain-stiffening behavior of silk fibroin gels. The gels are prepared from 4.2 w/v% fibroin solution in the presence of butanediol diglycidyl ether and N,N,N',N'-tetramethylethylenediamine (TEMED) as a cross-linker and catalyst, respectively. By changing the concentration of TEMED in the gelation system, fibroin gels exhibiting a storage modulus G' between 10−1-105 Pa and a loss factor tan δ between 10−2 and 10° could be obtained. We observe a strong stiffening (up to 900%) in fibroin gels with increasing strain above 10% deformation, but reversibly if the strain is removed, the gel recovers its initial viscoelastic properties. The strain induced formation of transient intermolecular domains acting as reversible cross-links are responsible for the stiffening behavior of fibroin gels. These additional cross-links formed in the hardened fibroin gels have a temporary nature with lifetimes of the order of seconds. The nonlinear behavior of fibroin gels can be reproduced by a wormlike chain model taking into account the entropic elasticity of fibroin molecules and the strain induced increase in the cross-link density of fibroin gels.
Related Topics
Life Sciences Biochemistry, Genetics and Molecular Biology Biochemistry
Authors
, ,