Facile Preparation of Mechanical Reinforced and Biocompatible Silk Gels

Nontoxic and controllable way to fabricate silk fibroin (SF) gel with high mechanical properties is of critical important to biomaterial in tissue engineering. Electrochemically triggered electrophoretic migration and electric charge of the silk molecules both contributed to SF microspheres and electronic gel (e-gel) formation by sol-gel transition. In this study, a novel silk pH e-gel with higher mechanical property was prepared by combining low-voltage electric fields with isoelectric point (pI) adjustment. This green process was mild and friendly without chemical crosslinker. Compressive modulus of the silk pH e-gel was up to 70 MPa that was significantly higher than that of SF gelation spontaneously. Furthermore, analysis of molecule conformation of the silk pH-e-gel demonstrated that most of random coil structures transformed into α-helix and a little β-sheet structures during this process. The silk pH e-gel was loaded with rhodamine B and showed an obvious sustainable release profile. Accumulation releasing amounts was approximately 60% at day 9. Cytocompatibility of the silk pH-e-gel was evaluated by epithelial cell. The results showed that the gels could support the cell growth and proliferation in vitro. Finally, gel biodegradation was assessed by protease XIV. After biodegradation for 28 days, remaining weight of the gel was about 20.23±2.59 wt%, indicating its good biodegradability. This novel process was established successfully by combining low voltage field with pH-control, which provided an alternative material for regenerative medicine.