The Preparation And Performance Study Of PCL/SF Complex Fibers Used In Nerve Scaffold

Electrospinning nanofibers can effectively simulate the extracellular matrix protein, its large specific surface area and complicity porous structure bring a broad application prospect in the field of tissue engineer scaffolds. Electrospinning technology is the most simple, cheap and efficient way to prepare nanoscale fibers, which bring lots of attention of many scientific workers. In this paper, natural polymer silk fibroin(SF) and biodegradable synthetic polymer poly(ε-caprolactone)(PCL) were used as the scaffold material, blended and sheath-core fibers were prepared by electrospinning technology, what combined the excellent biocompatibility of SF and excellent mechanical performance of PCL. The results showed that SF-PCL sheath-core fibers had potential application prospect in the field of nerve scaffold.By regulating the electrospinning process parameters, the best conditions for electrospinning were obtained. SF fibers, PCL fibers and PCL/SF blended fibers with neat appearance were prepared successfully. Moreover, FTIR, XRD, TG, contact angle and mechanical properties test were used to test the composition, structure and properties of the fibers. The use of methanol treatment could induce the phase transition of SF, and at the same time, PCL had a similar effect to the phase shift of SF. The hydrophilic and mechanical properties of PCL/SF blended fibers were between SF and PCL fibers, what could be found that the addition of SF effectively improved the system of the hydrophilic, and the existence of PCL had a good improvement to the mechanical properties of the system.Coaxial electrospinning technology was used to prepare SF-PCL sheath-core fibers, in which SF as the sheath and PCL as the core. The structure of sheath-core was more effective to combine the advantages of the two materials, what improved the hydrophilicity and biocompatibility of fibers by putting SF outside, and effectively maintained the excellent mechanical properties of inner core PCL fibers. SEM, TEM characterization indicated the existence of sheath-core structure, soaking sheath-core fibers with DMF brought a special section rod structure. XPS surface elemental analysis illustrated most of the fibers were existed in sheath-core structure. FTIR, TG, XRD test results showed the PCL and SF exists in the independence form in the fibers, which was compared with the test results of blended fibers. Contact angle and mechanical properties test results showed the contact angle value of sheath-core fibers was very close to SF fibers, and the tensile strength and elongation at break of sheath-core fibers was very close to PCL fibers, what declared the advantage of this kind of sheath-core structure.Dex was used as model drug and blended in the precursor solution, then Dex was loaded in fibers by electrospinning. In vitro drug release test was carried out, the test results showed that the SF-PCL sheath-core fibers had good drug controlled-release ability, which was due to the diameter and coating structure of the fiber. Through the comparative study on the morphology of the fiber before and after drug release found that the addition of Dex drugs lead to the production of reticular fibers, solvent swelling in the drug release process made an increase of the fibers’ diameters, and led to the production of specific secondary structure in the fibers.