Degradation Mechanism and Control of Blended Eri and Tasar Silk Nanofiber

Self-Assemble Silk Fibroin Microcapsules for Cartilage Regeneration through Gene Delivery and Immune Regulation

Effective treatments for cartilage defects are currently lacking. Gene delivery using proper delivery systems has shown great potential in cartilage regeneration. However, the inflammatory microenvironment generated by the defected cartilage severely affects the system's delivery efficiency. Therefore, this study reports a silk fibroin microcapsule (SFM) structure based on layer-by-layer self-assembly, in which interleukin-4 (IL-4) is modified on silk by click chemistry and loaded with lysyl oxidase plasmid DNA (LOX pDNA). The silk microcapsules display good biocompatibility and the release rate of genes can be adjusted by controlling the number of self-assembled layers. Moreover, the functionalized SFMs mixed with methacrylated gelatin (GelMA) exhibit good injectability. The IL-4 on the outer layer of the SFM can regulate macrophages to polarize toward the M2 type, thereby promoting cartilage matrix repair and inhibiting inflammation. The LOX pDNA loaded inside can be effectively delivered into cells to promote extracellular matrix generation, significantly promoting cartilage regeneration. The results of this study provide a promising biomaterial for cartilage repair, and this novel silk-based microcapsule delivery system can also provide strategies for the treatment of other diseases.

Mechanical and degradation properties of small-diameter vascular grafts in an in vitro biomimetic environment

Small-diameter vascular grafts may fail after implantation due to various reasons from mechanical and biological aspects. In order to evaluate the mechanical durability of small-diameter vascular grafts after implantation, an artificial vascular biomimetic environment that can simulate body temperature, the liquid environment outside the vessel, and continuous blood flow and pulsatile pressure was constructed. This device can be used as a “pre-test” prior to animal experiments to explore the changes of mechanical and degradation properties in the long-term in vivo environment. At the same time, braided tube-reinforced silk fibroin/poly (l-lactic acid-co-ε-caprolactone) small-diameter vascular grafts were fabricated and tested under the biomimetic environment. Mechanical changes, including tensile properties, suture retention strength, compliance, and degradation behavior of the braided tube-reinforced poly (l-lactic acid-co-ε-caprolactone)/silk fibroin small-diameter vascular grafts were explored over various periods of time in the biomimetic environment. The results shown that under a period of testing in the in vitro biomimetic environment, the comprehensive mechanical properties (including tensile properties, suture retention strength, estimated-bursting pressure, and compliance) of small-diameter vascular grafts exhibited varying degrees of changes but that there was no obvious degradation behavior in the short term.