Gelation Dynamics, Formation Mechanism, Functionalization, and 3D Bioprinting of Silk Fibroin Hydrogel Materials for Biomedical Applications

Abstract

Silk fibroin (SF), derived from silk cocoon fibers (Bombyx mori), is a natural protein polymer known for its biocompatibility, biodegradability, and sustainability. The protein can be processed into various material formats suitable for a range of applications. Among these, SF hydrogels are useful in the biomedical field, such as tissue engineering, due to the tailorable structures and properties achievable through tuning the gelation process. Therefore, the focus of this contribution is to comprehensively review and understand the formation, gelation mechanism, dynamic control, and functionalization of SF hydrogels. Unlike previous reviews, this work delves into understanding the strategies and mechanisms for tuning the gelation dynamics of SF from molecular assembly and crystallization points of view. Further, this review presents functionalization pathways and practical examples, such as for the 3D printing of SF hydrogels, to illustrate how these strategies, mechanisms, and pathways can be implemented in a specific application scenario. With these insights, researchers can gain a deeper understanding of how to manipulate or control the gelation process and the types of functionalization to achieve specific properties and features. This knowledge would further facilitate the development and application of SF hydrogel materials in various fields.

Keywords: 3D bioprinting; cross-linking; crystallization and functionalization; gelation mechanism and dynamics; injectable hydrogel; self-assembly; silk fibroin hydrogel; silk nanofiber.