丝素/褐藻多糖硫酸酯复合膜的理化性质

背景:丝素膜α-螺旋的结构是水溶性的而且不稳定,不能直接作为医用材料,具而β-折叠构象更为稳定.目的:利用褐藻多糖硫酸酯导致丝素膜的构象转变来制备β折叠构象的丝素膜,观察膜的理化件质.设计、时间及地点:生物材料复合膜的理化性质观察实验,于2003-11/2006-08在中科院北京化学所、承德石油高等专科学校化学实验中心完成.材料:褐藻多糖硫酸酯,从海带中提取,在承德石油高等专科学校化学实验中心完成,蚕丝购于中国进出口公司.方法:将丝素溶液和褐藻多糖硫酸酯的水溶液按一定比例混合,静置脱泡后,注入聚乙烯模具内,于25℃.相对湿度65%的环境干燥成膜,当褐藻多糖硫酸酯含量≤20%时,成膜性较好.根据复合膜中褐藻多糖硫酸酯和丝素的质量比0∶100、5∶95、10∶90、20∶80、100∶0,将膜分别标记.主要观察指标:采用红外光谱、X射线衍射、热失重分析表征观察制成膜的理化性质.结果:红外光谱、X射线衍射结果表明,由于褐藻多糖硫酸酯的引入,促使了丝素β-折替构象的形成.丝素从无规线团转变为β-折叠构象归结于丝素与褐藻多糖硫酸酯之间存在着氢键的相互作用.热失重分析表明,具有β-折叠结晶结构的丝素复合膜热稳定性要比无定形丝素膜高.结论:利用褐藻多糖硫酸酯导致丝素膜的构象转变来制备β折叠构象的丝素膜,构象的转变可通过红外光谱、X射线衍射证实.具有β-折叠结晶结构的丝素膜的热稳定性要比无定形丝素膜高.

Physical and chemical characteristics of silk fibroin/fucoidan composite films

BACKGROUND: Silk fibroin blend films with α-helix cannot be used as biomaterials due to water-soluble and unstable; however, β-sheet structure is stable. OBJECTIVE: To prepare for a β -sheet conformation silk fibroin composite films mixing fucoidan and to observe the physical and chemical characteristics of silk fibroin/fucoidan composite films. DESIGN, TIME AND SETTING: The physical and chemical characteristics experiments of silk fibroin/fucoidan composite films were conducted in Chemistry Experiment Center of Institute of Chemistry Chinese Academy of Sciences and Chengde Petroleum College from November 2003 to August 2006. MATERIALS: Fucoidan was isolated from Laminaria Japonica, and Bombyx mori silk was commercially from China Import & Export Company. METHODS: The solution prepared with a different blend ratios aqueous solution of silk fibroin and fucoidan, was cast into a polystyrene plate and incubated at 25 ℃ and 65% relative humidity. Silk fibroin film was formed after dry the plate at the temperature. The composite films were well when the mixing rate of fucoidan was more than 20% (w). The silk fibroin solution and fucoidan solution were mixed according to the different mass ratios of silk fibroin and fucoidan, including 0∶100, 5∶95, 10∶90, 20:80, and 100∶0. The films were marked a, b, c, d and e, respectively. MAIN OUTCOME MEASURES: The physical and chemical characteristics of silk fibroin/fucoidan composite films were examined through Fourier transform infrared spectroscopy, X-rey diffractometry, and thermogravimetry. RESULTS: The conformation of silk fibroin in blend films was revealed to be β-sheet structure according to the results of Fourier transform infrared and X-ray diffractometry spectra. These results demonstrated that the conformation change of silk fibroin occurred from a random coil to a β-sheet structure due to the formation of intermolecular hydrogen bonds between fucoidan and silk fibroin in the blend films. Thermogravimetry showed that the crystalline silk fibroin films had higher thermal stability than the amorphous silk fibroin film. CONCLUSION: The conformation of silk fibroin in composite films was revealed to be a β -sheet structure according to the results of Fourier transform infrared and X-ray diffractometry spectra. The crystalline silk fibroin films showed higher thermal stability than the amorphous silk fibroin film.