关键词: 壳聚糖, 丝素蛋白, 同轴静电纺丝, 抗菌, 体外生物活性

Abstract: At present, bone defects caused by trauma, infection, bone tumors, etc. are very common, suffering from major diseases that cause serious bone damage often exceeds the bone's self-healing ability, but the bone tissue's own repair and regeneration ability does not reach the perfect repair, in this case, we need to find a better repair material to treat these bone injury diseases. As natural polymers, chitosan (CS) and silk fibroin (SF) are widely available and easy to obtain, and they will only degrade to water and carbon dioxide when implanted into the human body, so they have good biocompatibility and degradability. In this paper, CSPEO-SF nanofibers were prepared by coaxial electrostatic spinning technology. The shell layer of CS and PEO can ensure the fibers to have good hydrophilic properties, antimicrobial properties, and in vitro bioactivity, and the SF in the core layer serves as a core template to ensure the fibers to have certain mechanical strength, and then glutaraldehyde (GA) was used to transform some of the amino groups in the fibers into aldimine groups to improve the water resistance of the fiber membrane. Tests such as XRD and FTIR were carried out on the fibers before and after cross-linking, and it was found that the aldehyde-imide groups were successfully produced after cross-linking, and it was concluded from the SEM images that the fiber diameters increased after cross-linking, and the fracture strength increased, but the tensile strain decreased. Different nanofibers were prepared by varying the mass ratio of CS, PEO and SF, and it was observed from the SEM plots that the fiber diameter increased with the increase in the mass proportion of PEO and SF. After that the mechanical properties, porosity and swelling properties were tested, the increase of both CS and SF ratio decreases the flexibility, swelling properties and porosity of the fibers, but increases the mechanical properties of the fibers, and all the fibers were able to reach a porosity of more than 80%, and a swelling rate of up to 675%. Finally, comparing the results of the above tests, the more balanced C7P3S10 samples were selected to compare with the SF fibers for the subsequent antimicrobial performance and in vitro bioactivity tests. Antimicrobial experiments are reflected by the dilution coating plate method, firstly, the fibers are mixed with the appropriate amount of bacterial solution for 8 h, and then the cultured bacterial solution is coated onto agar medium for 24 h, and the number of colonies on the medium is observed and recorded, and compared with the blank control group, the rate of bacterial inhibition is calculated, and it is found that from the results of the experiment that although the antimicrobial performance of CSPEO-SF fibers after the cross-linking modification treatment is decreased, but it is still stronger than SF fiber. The in vitro bioactivity experiment was conducted by immersing the fibers in simulated body fluid (SBF) at a ratio of 1.5 mg/mL for a period of time to observe the generation of hydroxyapatite (HA), which revealed that the Ca/P ratio of HA on the surface of CSPEO-SF fibers was closer to that of human bone, and that the in vitro bioactivity of CSPEO-SF fibers was better than that of SF fibers. Through the above experiments, it can be concluded that CSPEO-SF fibers can have a wide range of applications in biomedical applications.

Key words: Chitosan, Silk proteins, Coaxial electrostatic spinning, Antimicrobial properties, In vitro bioactivity