以電紡絲法製備幾丁聚醣/硫酸軟骨素/聚乙烯醇複合奈米纖維之研究

Abstract

先前研究發現，幾丁聚醣/硫酸軟骨素形成之複合材料有利於骨細胞體外培養。此外，立體奈米纖維支架與體內胞外間質環境較相似，理論上有助於細胞貼附與生長。因此本研究主要目的為將幾丁聚醣/硫酸軟骨素/聚乙烯醇形成之複合材料以電紡絲法紡織成奈米級纖維。實驗嘗試使用之溶液總濃度分別為14 wt%、12 wt%、10 wt%，並依幾丁聚醣與聚乙烯醇比例，可分為1:1、2:1、3:1三種不同混合比例。實驗操作之電壓為15、20、25、30 kV四組變數，流量則為0.005 mL/min、0.0075 mL/min、0.01 mL/min三組，探討製程參數之效應。 本研究發現除了部分黏度過高與濃度過低之組別，大多數組別皆可順利電紡成絲。溶液的總濃度增加與聚乙烯醇的增加，可以得到型態較佳之纖維，直徑約為100 - 400 nm 。電壓與流量對纖維直徑並無明顯影響。當提高溶液中聚乙烯醇的比例，所得纖維的直徑會隨之變粗。根據FT-IR之結果可以看出硫酸軟骨素與幾丁聚醣間存在以硫酸基與胺基形成之共價鍵結；熱分析之結果得知聚乙烯醇與幾丁聚醣為物理性混合且無明顯分相現象。 於抗張強度測試中，薄膜交聯後其楊氏彈性係數由9.72±2.2 MPa升高為174.0±24.0 MPa。交聯前之最大拉伸應力為65.7±6.7 N/g，最大延展量為30.6±5.8%；經由戊二醛交聯過24小時的薄膜，其最大拉伸應力降低為35.0±1.1 N/g，最大延展量降為5.5±2.1%，可能因戊二醛交聯過度所致，此點尚待改進。然而仍須透過戊二醛交聯以穩定其結構，交聯後之組別，經過14天降解後其殘存重量為原本之70 %，而未交聯之組別其殘存重量僅有初始重量之50 %，證實利用戊二醛交聯可減緩電紡絲纖維之降解程度。總之，本研究成功的將幾丁聚醣/硫酸軟骨素/聚乙烯醇電紡絲成奈米纖維，並探討其製程之相關參數對纖維型態之影響，希冀未來可將此類纖維應用於組織工程相關領域。

Previous researches indicate that chitosan/chondroitin sulfate composite materials benefit the in vitro proliferation of bone cells. Besides, 3D nanofibrous scaffold is similar to the extra cellular matrix , which may help cell attachment and proliferation. The aim of this research is to fabricate chitosan/chondroitin sulfate/polyvinyl alcohol composite nanofibers by electrospinning. In the experiments, the total concentration of solutions were 14, 12, and 10 wt%; the ratios of chitosan to polyvinyl alcohol were 1:1, 2:1 and 3:1. The voltages applied were 15, 20, 25, and 30 kV. The flow rates were 0.005, 0.0075, and 0.01 mL/min. The effects of these process parameters on the composite nanofibers were investigated. According to the results, by increasing the total concentration of solutions and the ratio of polyvinyl alcohol, we could collect nanofibers with better morphology, the diameters of the fibers were 100-400 nm. The voltage applied and the flow rate had little effect on the diameter of fibers. When increasing the ratio of polyvinyl alcohol, the diameter of nanofibers also increased. According to FT-IR analysis, there’s covalent bonding between sulfate group of chondroitin sulfate and amide group of chitosan. The results of thermal analysis showed that chitosan and polyvinyl alcohol were physically blended. In tensile strength test, the Young’s modules of electronspun mats (after cross-linked by glutaraldehyde for 24 hours) increased from 9.7±2.2 MPa to 174.0±24.0 MPa. But the maximum tensile stress decreased from 65.7±6.7 N/g to 35.0±1.1 N/g, also the maximum elongation decreased from 30.6±5.8 % to 5.5±2.1 %. However, the degradation rate of electrospun mats was fast, and thus cross-linking by glutaraldehyde was needed to stabilize the structure. After 14-day degradation in PBS, the remaining weight of crosslinked fiber was 70% of the original. The remaining weight of uncrosslinked was only 50% of the original, indicating that glutaraldehyde cross-linking treatment reduced the degradation of electrospun mats. In this research, chitosan/chondroitin sulfate/polyvinyl alcohol composite nanofibrous scaffold was successfully fabricated via electrospinnnig. The effects of various process parameters on the nanofibers were also investigated. It is expected that the materials can be applied in tissue engineering related areas.