Strategies for Tuning the Biodegradation of Silk Fibroin-Based Materials for Tissue Engineering Applications

The remarkable features of silk fibroin (SF) from the silkworm (Bombyx mori) have fueled its application as a candidate biomaterial for tissue regeneration and repair. For an ideal scaffold, the rate of degradation should be synchronized to match the rate of new tissue formation, and tuning this rate is essential, as diverse tissues differ in terms of regeneration period. In this Review, we discuss the factors influencing the degradability of SF, which can vary from days to several months, depending on the state of the raw material, the scaffold preparation process, morphological features, and host factors. This knowledge facilitates strategies for tuning the SF degradation rate, including manipulation of molecular weight, crystalline level, and cross-linking degree. Since these strategies have a great influence on the mechanical properties, the superiority of SF has to be sacrificed to satisfy the requirements for degradation rate. We further explore additional strategies, including the incorporation of degradation-promoting supplements such as blending with another polymer (e.g., gelatin) and the incorporation of enzyme-sensitive peptides. The information in this Review will likely aid scientists working with SF materials for the regeneration of diverse tissues.