Preparation of Silk Fibroin/Carboxymethyl Chitosan Hydrogel under Low Voltage as a Wound Dressing

At present, silk fibroin (SF) hydrogel can be prepared by means of electrodeposition at 25 V in direct current (DC) mode. Reducing the applied voltage would provide benefits, including lower fabrication costs, less risk of high voltage shocks, and better stability of devices. Here, a simple but uncommon strategy for SF-based hydrogel preparation using 4 V in DC mode is discussed. SF was mixed and cross-linked with carboxymethyl chitosan (CMCS) through hydrogen bonding, then co-deposited on the graphite electrode. The thickness, mass, and shape of the SF/CMCS hydrogel were easily controlled by adjusting the electrodeposition parameters. Morphological characterization of the prepared hydrogel via SEM revealed a porous network within the fabricated hydrogel. This structure was due to intermolecular hydrogen bonding between SF and CMCS, according to the results of thermogravimetric analysis and rheological measurements. As a potential wound dressing, SF/CMCS hydrogel maintained a suitable moisture environment for wound healing and demonstrated distinct properties in terms of promoting the proliferation of HEK-293 cells and antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, histological studies were conducted on a full-thickness skin wound in rats covered with the SF/CMCS hydrogel, with results indicating that this hydrogel can promote wound re-epithelization and enhance granulation tissue formation. These results illustrate the feasibility of using the developed strategy for SF-based hydrogel fabrication in practice for wound dressing.