Effect of silk fibroin molecular weight on physical property of silk hydrogel

•Molecular weight of SF critically affected the physical properties of SF hydrogel.•Microscopic structure and secondary structure of SF hydrogel affected the optical property of SF hydrogel.•SF hydrogel with different molecular weight could be utilized for diverse purpose in biomedical engineering.

Silk hydrogel has recently received great attention for its excellent biocompatibility. The property of silk hydrogel is, however, not only hardly controlled but very limited due to non-variability of silk fibroin (SF) molecule. In this study, alkaline hydrolysis was utilized to manipulate the silk hydrogel properties. By regulating the hydrolysis time (10-180 min), a broad molecular weight range of SF was obtained (263.1-82.7 kDa) Gel point increased with a decrease of SF molecular weight. The change of molecular weight of SF also greatly affected the physical properties (i.e., swelling ratio, shear modulus, transparency) as well as cell adhesion of SF hydrogels. As a result of structural analysis, the molecular weight of SF played a crucial role in the construction of microscopic structure of SF hydrogel. These findings indicate that SF hydrogels of variable physical properties can be fabricated based on molecular weight control for diverse purposes in biomedical engineering.

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