Abstract:

Objective Silk fibroin (SF) is a macromolecular protein derived from silk. In recent years, silk-based biomaterials have been studied and applied in the field of wound repair and become the preferred material for wound dressing. However, single silk fibroin-based biomaterials have weak antibacterial performance, which limits their application in wound dressing. Meanwhile, chitosan (CS) has non-toxicity, good biocompatibility and strong antibacterial properties, and has a wide range of applications in the field of medical dressings. Electrospinning technology has potential development in the field of wound dressing and is potential for developing fiber membrane materials with excellent performance.

Method With hexafluoropropanol and trifluoroacetic acid as solvent, silk fibroin was dissolved to prepare chitosan blended spinning solution. Electrospinning was adopted to prepare the composite fiber membrane, and the silk fibroin/chitosan composite fiber membrane microstructure was studied to determine bibulous rate and to characterize the hemostatic and antibacterial properties.

Results Before ethanol soaking, the fibers of pure silk fibroin membrane SF were smooth and loose, without bead shape, but after ethanol soaking, the fibers became dense and reticular. After the addition of chitosan, the SF/CS composite fiber membrane fibers became thinner. The network structure of electrospinning was conducive to the increase and proliferation of cell binding sites when the fiber membrane touches the wound (Fig. 1). The absorption peaks of amide I at 1 625 cm^-1 and amide II at 1 520 cm^-1 were present for the composite fiber membranes. Chitosan has sec-alcohol hydroxyl at 1 029 cm^-1 υ(C—O). It was seen that the typical characteristic peaks of CS and SF appeared for SF/CS composite fiber membranes, indicating that SF and CS were physically mixed and no new substances were produced (Fig. 2). In the process of increasing chitosan content, the water absorption of composite fiber membrane were increased followed by a decrease. Compared with hemostatic gauze, the absorbency of the composite fiber membrane was significantly improved (Fig. 3). With the increase of chitosan content, the blood absorbed by SF/CS composite fiber membrane increased, and the color of supernatant gradually became lighter. Its in vitro coagulation-promoting capability was superior to that of hemostatic gauze (Fig. 4). With the increase of chitosan content, the coagulation time of SF/CS composite fiber membrane was gradually shortened, among which, SF/CS4(the mass ratio of SF to CS of 5∶2) composite fiber membrane had the shortest coagulation time and the best coagulation effect (Fig. 5). With the increase of chitosan content, the antibacterial effect of SF/CS composite fiber membrane on the two strains was gradually enhanced. The antibacterial effect of SF/CS composite fiber membrane on Staphylococcus aureus was obviously better than that on Escherichia coli. When the mass ratio of silk fibroin to chitosan was 5∶2, the bacteria inhibition rate against Escherichia coli was (73.93±0.85)%, the bacteria inhibition zone diameter was (11.88±0.04) mm, and the bacteria inhibition zone diameter against Staphylococcus aureus was (93.27±0.97)%, the bacteria inhibition zone diameter was (15.34±0.04) mm (Fig. 6 and Fig. 7).

Conclusion Silk fibroin/chitosan composite fiber membranes with different mass ratios were prepared by electrospinning technology, and their micromorphology, water absorption, hemostatic and bacteria inhibition properties were investigated. The antibacterial activity and hemostatic performance of composite fiber membranes are closely related to the content of chitosan. When the mass ratio of silk fibroin to chitosan is 5∶2, the composite fiber membrane SF/CS4 has higher water absorption and better antibacterial effect. Meanwhile, the results of hemostatic performance test show that the composite fiber membrane SF/CS4 has smaller in vitro coagulation index and shorter in vitro coagulation time. Hemostatic performance is better than hemostatic gauze. The composite fiber membrane material prepared with silk fibroin-based has good performance, which is worth further exploration for application for wound healing.

Key words: nanofiber membrane, electrospinning, silk fibroin, chitosan, hemostatic material, antibacterial material