【作者】 费燕娜；

【导师】 高卫东； 王鸿博；

【作者基本信息】 江南大学 ， 纺织工程， 2013， 博士

【摘要】 当聚合物纤维直径达到纳米级时，便会出现一系列优异的特性，这些特性使得聚合物纳米纤维及其制品在众多领域具有极高的研究价值及潜在应用价值。静电纺丝技术是目前制备纳米纤维最经济有效的方法之一，其制备的纳米纤维连续且均匀，性能良好，成为人们研究聚合物纳米纤维及其制品的首选方法。然而研究目的的不同，对聚合物种类的性质及功能的要求也不尽相同。为了赋予研究材料功能的最大化以及弥补某种单一材料性能上的不足，可以把研究对象从一种聚合物拓展为两种或两种以上的聚合物、也可以在一种聚合物中添加功能性材料。本文采用生物相容性好的高分子材料聚乳酸（Polylactide，PLA）作为基材，与具有多种功效及各种药理药效的茶多酚（TeaPolyphenol，TP）混合，采用静电纺丝的方法制备出PLA/TP复合纳米纤维膜，对其纺丝工艺及各种性能进行研究，主要内容及相关结论如下：（1）PLA/TP复合纳米纤维膜纺丝方案的确定。通过扫描电子显微镜（SEM）图，分析对比纤维形貌，优化各实验方案条件下的试验参数。首先研究纺丝溶质浓度及纺丝溶剂对纳米纤维成型及形貌的影响。SEM图显示，当溶质质量分数小于或大于10%时，不是珠节状和纺锤体状纤维甚多，就是纤维直径偏大，因此确定溶质质量分数为10%。其次对于纺丝溶剂的选择，为了改善纤维形貌，并考虑到后续添加物TP的溶解问题，加入N，N-二甲基甲酰胺（DMF）与二氯甲烷（DCM）组成二元混合溶剂。通过SEM图，发现DMF的确是一种理想良溶剂，并确定出DCM/DMF体积比为7/3，所纺纤维均匀性最好。确定纺丝过程参数分别为纺丝电压18kV、纺丝距离17.5cm及纺丝速度0.8mL/h。纺丝方案确定后，对不同PLA/TP质量比对复合纳米纤维膜相貌的影响进行分析。研究了TP对混合纺丝溶液性质及直径的的影响。当两者质量比在100/0-50/50范围内变化时，PLA/TP复合纳米纤维平均直径从854nm下降到380nm，再继续改变两者质量比，则出现纤维断裂甚至不成纤的情况。（2）PLA/TP复合纳米纤维膜结构和性能研究。在PLA/TP不同质量比条件下制备的复合纳米纤维膜，傅里叶红外光谱（FTIR）分析结果显示：50/50时，复合薄膜在3550-3200cm-1处出现宽羟基缔合特征伸缩振动吸收峰，并出现取代苯的特征吸收峰，证实PLA/TP复合纳米纤维膜中两者之间通过价键的作用结合在一起；差示扫描量热仪（DSC）测试结果表明随着复合纳米纤维膜中两者成分的变化，结晶结构、玻璃化转变温度（Tg）及熔融温度（Tm）均会发生变化：50/50较纯PLA薄膜，Tg略有下降5℃，90/10时，Tm由150℃上升至163℃，同时复合薄膜中结晶区减少，无定形区增加。润湿性能测试结果表明TP含量的增加，接触角从138.49°减小为127.49°，粘附功及表面能也相应增加，但仍属疏水材料范畴，润湿性能稍有改善。力学性能测试结果显示PLA的减少，导致拉伸强度下降，TP的增加使断裂伸长率先增加后减小，应力-应变曲线告诉我们复合薄膜的类型因PLA/TP质量比的不同而不同。孔径分析结果显示PLA/TP不同质量比条件下的复合纳米纤维膜较纯PLA薄膜，小孔径所占比重增大，孔径分布更密集。（3）PLA/TP复合纳米纤维膜抗菌性能的测试及机理的研究。通过对PLA/TP不同质量比复合纳米纤维膜进行振荡烧瓶法和抑菌圈法抗菌性能测试，结果表明添加TP的复合纳米纤维膜抗菌性能较纯PLA纳米纤维膜明显提高，且随着TP含量的增加，抗菌性能提高。对金黄色葡萄球菌（S. aureus）及大肠杆菌（E. coli）的抑菌率与抑菌圈宽度分别增加了76.4%、76.3%与1.96cm、1.5cm。鉴于抗菌测试结果，提出了基于分子理论上的PLA/TP复合纳米纤维膜的抗菌模型，通过多酚羟基与脂质双分子层的吸附及蛋白质分子的络合，破坏细胞膜的完整性及通透性。流式细胞仪（FACS）分析结果显示S.aureus和经PLA/TP（50/50）复合薄膜处理后，碘化丙啶（PI）的染色率分别增加至9.26%和6.47%，鉴于PI染料能够进入不完整细胞膜的性质，得出结论：PLA/TP复合纳米膜的作用靶点是菌体细胞膜，通过破坏其完整性，导致最后死亡。透射电子显微镜（TEM）实验结果也从菌体的微观结构上做出了验证。直观的显示了复合薄膜对两种菌体膜结构的破坏作用，并且对S. aureus的破坏作用要强于E. coli。FACS+TEM的联合论证有力的支持了抗菌模型的理论。（4）PLA/TP复合纳米纤维膜TP缓释性能及薄膜降解性能研究。提出了PLA/TP复合纳米纤维膜TP的释放模型。通过在TP最大波长处测定各不同浓度的吸光度值，利用分析软件得到关于TP的标准曲线方程。根据该方程及测定的不同时间点各溶液的吸光度值，得到PLA/TP不同质量比复合纳米纤维膜在72h内的累积释药曲线，结果表明该复合薄膜具备药物缓释性能，且在释药第一阶段，速度较快，之后变缓，逐渐趋于平稳。同时通过SEM图的观察及pH值的测定，证明PLA是一种良好的可生物降解载体，降解8周时间后，50/50复合薄膜pH值仍维持在7.1左右。证实PLA的降解对药物的释放具有一定的促进作用。更多还原

【Abstract】 When the polymer fiber diameter decreased from micron to nanometer level, there willbe a series of excellent characteristics, which make the polymer nanometer fiber and itsproducts have high research and potential application value in many fields. Theelectrospinning technology is one of the most economic methods to prepare nano-fiber.,which is continuous, uniform and have good performance. So this technology has become thefirst choice to prepare nano-fiber and its products. However, different research objectivesrequire the polymer with different types, performances and functions. In order to maximizethe function of the research material and make up for the lack of performance of a singlematerial, the research object is expanded from one kind of polymer to two or more kinds. Thepolylactic acid (PLA) polymer with good biocompatibility was used as a substrate, andmixtured with Tea Polyphenol, which has many functions and various pharmacological effects. The PLA/TP composite nanofiber membrane was prepared by electrospinning process. Thespinning process and the performance were studied, and the main research contents andconclusions have the following several parts:(1) Determine the best parameters of electrospinning the PLA/TP composite nanofibermembranes. Firstly, through the scanning electron microscopy (SEM) to observe and analysisthe morphology of the fibers, the optimal experimental parameters of each experimentalcondition were determined. The results showed that: the quality score of PLA and TP hasgreat influence on the spinning process. The SEM images show when the mass fraction ofPLA is less than or greater than10%, the spinnability and the diameters of the fibers can’t bethe best, so to determine the solute mass fraction is10%. Secondly, the aim is to determinethe spinning solvent. Through the SEM images and considering the experimental efficiencyand effect, the electrospinning solvent was the mixed solution of dichloromethane (DCM) andN, N-two dimethyl formamide (DMF), and the volume ratio (V/V) was7/3. Throughstudying the influences of different spinning conditions on the morphologies of PLA/TPcomposite nanofibers, and using the SEM images and distributions of the fibers’ diameters,the spinning voltage, spinning distance and spinning speed were determined as18kV,17.5cmand0.8mL/h. Finally, to research different quality blending ratios of PLA and TP have theinfluence on the compound nanofibers. Through analysising the influence of different qualitymixed ratio on the electrospinning solution’s properties, including solution viscosity,conductivity, surface tension. And through comparing the SEM images and distributions ofthe fibers’ diameters, we can draw the conclusion: the fiber diameter will be smaller with theincrease content of TP.(2) Research on the structure and performance of the PLA/TP composite nanofibrous me-mbranes. The PLA/TP composite nanofibrous membranes were prepared in the condition ofdifferent mixing ratio of PLA/TP. The structures of the membranes were characterized byFourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC),and the wetting properties, mechanical properties and pore size distribution were tested andanalyzed. The results showed: the two components of PLA and TP existed in the composite membranes, and bonded together by valence bond. The DSC test results showed that: with thechange of the two composites in the nanofibrous membrane, the crystalline structure, glasstransition temperature (Tg) and melting temperature (Tm) would also change. The contactangle test results showed that: with the decrease of PLA and the increase of TP in thecomposite nanofibrous membranes, the wettability of the membranes was improved. Themechanical testing results also showed that: the tensile strength and elongation of thecomposite nanofibrous membranes had a downward trend with the decrease of PLA and theincrease of TP in the membranes. The pore size analysis results make us understand that: withdifferent quality of mixing ratio of the composites, the pore size and distribution conditionsare different in nanofibrous membranes.(3) Test the antibacterial property and study on the mechanism of the PLA/TP compositenanofibrous membrane. Through testing the composite nanofibrous membranes with differentquality ratios of PLA and TP by oscillation flask method and inhibition zone test, the resultshowed that: the antibacterial property of the composite nanofibrous membrane wasimproved with adding TP, and the effect was more obvious with the increase of TP content.The antibacterial rate and bacteriostatic ring width of the Staphylococcus aureus (S. aureus)and Escherichia coli (E. coli) membranes were increased by76.4%,76.3%and1.96cm,1.5cm. The antimicrobial modle of PLA/TP composite nanofibrous membranes was proposedbased on the molecular theory. The lipid bilayer was adsorbed and protein molecule wascomplexed by phenolic hydroxyl group, then the integrity and permeability of cell membranewas damaged. The test results of flow cytometry (FACS) and transmission electronmicroscopy (TEM) showed that: one of the antibacterial mechanisms is to destroy theintegrality of cell membrane, which result in the death of bacteria.(4) Study on the sustained-release properties of PLA/TP composite nanofibrous membrane.The release modle of TP in PLA/TP composite nanofibrous mambranes was proposed. Theabsorbances at different concentration of TP at the maximum wavelength were measured, andthe TP standard curve equation was obtained by analysis software. According to the equationand the absorbance of each solutions, the sustained-release curve of the PLA/TP compositenanofibrous membranes within72hours was drawn, which showed the composite film hadsustained-release property. After degradationof8weeks, the pH value of50/50compositefilms was maintained at about7.1. At the same time, the SEM images and the pH valueshowed that PLA was a good biodegradable carrier and had a certain role in promoting thesustained-release property.更多还原