Silk fibroin-based liquid metal conductive hydrogel as an advanced wound dressing facilitates the wound repair

Electroactive hydrogels can endow wound dressing with novel functionalities including electrical activity, antibacterial properties and strong adhesion. Among various natural hydrogel substrates, silk fibroin (SF) and chitosan (CS) have garnered significant attention from researchers due to their ability to promote cell proliferation and migration as well as to accelerate wound healing, particularly in the case of SF. In this work, tannic acid (TA) was employed as a stabilizer and ultrasonic method was utilized to prepare the conductive filler. The average diameter of liquid metal nanodroplets (LMND) in an absolute ethanol solution containing 0.2% TA was measured to be 207.6 nm. The stability test results also demonstrated that TA effectively enhanced the colloidal stability of LMND, with the LMND suspension maintaining good dispersion even after standing for 12 h. To address the issue of hydrogel rigidity caused by metal particles and conductive polymers as fillers, we tackled this problem by blending methacrylated silk fibroin (SFMA) and methacrylated chitosan (CSMA) with liquid metal droplets and subsequently curing the solution into a conductive hydrogel through photocrosslinking. The resulting conductive hydrogel exhibited remarkable antibacterial properties and tissue adhesion, achieving a conductivity of 0.038 mS/cm at a liquid metal content of 5%. In vitro cytotoxicity experiments revealed that NIH 3 T3 cell viability remained above 98% after co-culturing with the hydrogel material for 72 h. Furthermore, hydrogels incorporating liquid metals displayed superior cytocompatibility compared to those without liquid metals.