【作者】 张健；

【导师】 王军辉； 刘咏；

【作者基本信息】 合肥工业大学 ， 生物工程（专业学位）， 2019， 硕士

【摘要】 石耳（Umbilicaria esculenta（Miyoshi）Minks）是一种由真菌和藻类共生形成的复合体,属地衣门石耳科石耳属,黄山石耳多糖（HSSE）是从黄山石耳中制备的多糖组分。本论文在多糖HSSE/氢氧化钠/尿素体系中,以环氧氯丙烷（ECH）作为交联剂构建多糖基水凝胶,并在多糖基水凝胶基础上制备温度敏感水凝胶,阐明这些水凝胶的理化性质,拓展多糖HSSE在生物材料领域的应用范围。实验结果如下:（1）采用高分子技术的方法,研究氢氧化钠与尿素配比及温度对多糖HSSE溶液稳定性的影响。结果表明,低温（10°C）下,多糖HSSE在6 wt%氢氧化钠/4wt%尿素溶液中单分散体与聚集体比最高为1.18,粘度为107.6 cm³·g^-1,体系主要以单分散体包合物构成,溶液最稳定,为后期水凝胶的构建提供稳定的多糖溶剂。（2）在氢氧化钠/尿素体系中,通过引入环氧氯丙烷作交联剂,制备多糖HSSE水凝胶。流变结果表明:多糖HSSE/环氧氯丙烷体系的溶液-凝胶转变是多糖HSSE浓度、环氧氯丙烷含量、温度与时间的函数关系。体系中多糖HSSE浓度从8 wt%升高到12 wt%,凝胶点从28 min缩短到22 min。环氧氯丙烷含量从10%升高到14%,凝胶点从36 min缩短到22 min。温度升高使体系的凝胶化时间缩短。FT-IR结果显示,多糖HSSE水凝胶中多糖特征吸收峰在3400 cm^-1和2900 cm^-1处;环氧氯丙烷特征吸收峰在1460 cm^-1和856 cm^-1处,这些特征峰出现证明了多糖HSSE与环氧氯丙烷存在于凝胶体系中,整个网络结构已成功构建。SEM结果显示,水凝胶内部为多孔结构,孔径范围在6-50μm之间,且孔洞大小与多糖HSSE和交联剂浓度密切相关。溶胀结果显示,多糖浓度从8 wt%升高到14 wt%,水凝胶的溶胀率从17.7 g/g下降到9.7 g/g;交联剂含量从10 v/v%升高到14 v/v%,水凝胶溶胀率从15.3 g/g下降到10.3 g/g。多糖HSSE水凝胶的保水能力随着多糖和环氧氯丙烷含量的增加而升高。胞外毒性实验证明多糖HSSE水凝胶没有细胞毒性作用。（3）在纯多糖HSSE水凝胶基础上,通过引入聚（N-异丙基丙烯酞胺）（PNIPAAm）制备温度敏感型水凝胶（IPN）。在IPN水凝胶中第一层网络（多糖HSSE）主要起结构支撑作用,第二层网络（PNIPAAm）主要贡献于温度敏感性。SEM结果表明,IPN水凝胶具备更加紧密的三维网络和均匀的多孔结构。FT-IR和TGA结果表明,第一层网络和第二层网络是相互独立存在的,二者之间存在很强的氢键作用但没有新的化学键的形成。DSC和溶胀结果表明,IPN水凝胶最低临界温度（LCST）出现在32°C附近,当温度高于LCST,IPN水凝胶迅速收缩,溶胀率显著下降,表现出典型的温度敏感曲线。以牛血清蛋白作为模型药物的体外释放行为结果显示,药物释放速率与释放量随IPN水凝胶中PNIPAAm含量升高而增加,最大释放量为91.5%。当温度在37°C时（高于LCST）,IPN水凝胶的药物释放速率恒定,温度在25°C时（低于LCST）,IPN水凝胶出现爆释现象。胞外毒性实验证明了IPN水凝胶无细胞毒性,体现良好的生物相容性。更多还原

【Abstract】 Umbilicaria esculenta（Miyoshi）Minks,a complex formed by the symbiosis of fungi and algae,belong to the genus Lithocarpus.Huangshan Stone Ear Polysaccharide（HSSE）is a polysaccharide component prepared from Huangshan stone ear.In this paper,polysaccharide hydrogels were constructed using epichlorohydrin（ECH）as a cross-linking agent in polysaccharide HSSE/sodium hydroxide/urea system,and temperature-sensitive hydrogels were prepared on the basis of polysaccharide hydrogels,so as to clarify the physical and chemical properties of these hydrogels and expand the application scope of polysaccharide HSSE in the field of biological materials.The experimental results are as follows:（1）The effects of the ratio of sodium hydroxide to urea and the temperature on the stability of polysaccharide HSSE solution was studied by means of macromolecule method.The system mainly composed of a monodisperse inclusion compound,and the solution was the most stable,providing a stable polysaccharide solvent for the later hydrogel construction.（2）In the sodium hydroxide/urea water system,epichlorohydrin was introduced as a crosslinking agent to prepare a polysaccharide HSSE hydrogel.The rheological results showed that:the solution-gel transition of the polysaccharide HSSE/epichlorohydrin system is a function of HSSE concentration,epichlorohydrin content,and temperature.The concentration of polysaccharide HSSE in the system increased from 8 wt%to 12wt%,and the gel point decreased from 28 min to 22 min.The epichlorohydrin content increased from 10%to 14%and the gel point was shortened from 36 min to 22 min.An increase in temperature shortens the gelation time of the system.The results of FT-IR showed that the characteristic absorption peaks of polysaccharides in polysaccharide HSSE hydrogel were 3400 cm^-11 and 2900 cm^-1,respectively;the characteristic absorption peaks of epichlorohydrin were 1460 cm^-11 and 856 cm^-1,respectively.The appearance of characteristic peaks proved that polysaccharide HSSE and epichlorohydrin existed in the gel system,and the entire network structure had been successfully constructed.The SEM results showed that the hydrogel has a porous structure with a pore size ranging from 6 to 50μm.An increase in the concentration of the polysaccharide HSSE and the crosslinker resulted in a decrease in the pore size.The swelling results showed that the polysaccharide concentration increased from 8 wt%to14 wt%,the swelling rate of the hydrogel decreased from 17.7 g/g to 9.7 g/g;the crosslinker content increased from 10 v/v%to 14 v/v%,the hydrogel swelling rate decreased from 15.3 g/g to 10.3 g/g.The water retention capacity of the polysaccharide HSSE hydrogel increased with the increase of polysaccharide and epichlorohydrin content.Extracellular toxicity experiments demonstrated that polysaccharide HSSE hydrogels have no cytotoxic effects.（3）Based on the polysaccharide HSSE hydrogel,a temperature-sensitive hydrogel（IPN）was prepared by introducing poly（N-isopropylacrylamide）（PNIPAAm）.The SEM results showed that the IPN hydrogel has a tighter three-dimensional network and a uniform porous structure.The results of FT-IR and TGA showed that the first layer network and the second layer network are independent of each other,and there is a strong hydrogen bond between them,but no new chemical bonds are formed.DSC and swelling results showed that the lower critical solution temperature（LCST）of IPN hydrogel appeared near 32°C,when the temperature was higher than LCST,the IPN hydrogel contracted rapidly and the swelling rate decreased significantly,showing a typical temperature sensitivity curve.The vitro release behavior of bovine serum albumin as a model drug showed that the drug release rate and release amount increased with the increase of PNIPAAm content in IPN hydrogel,and the maximum release amount was 91.5%.When the temperature at 37°C（above LCST）,the drug release rate was constant,and at 32°C（below LCST）,the IPN hydrogel showed a burst release.Extracellular toxicity experiments have demonstrated that IPN hydrogels are non-cytotoxic and exhibit good biocompatibility.更多还原