【作者】 樊宏鑫；

【导师】 邹凤竹；

【作者基本信息】 山东农业大学 ， 特种经济动物饲养， 2010， 硕士

【摘要】 生物可降解材料具有优良的生物相容性与理化性能,在生物医学领域得到了广泛应用。本文以组织工程支架应用为目的,分别制备了丝素-纳米四氧化三铁复合水凝胶和PLLA/PBS超细纤维膜两种生物可降解复合材料,并通过扫描电镜、热重分析、机械拉伸等分析测试手段对复合材料进行了结构表征和性能测试。具体研究结果如下:1 .建立了一套实验室制备丝素蛋白水凝胶的工艺流程,并制得了形貌较为规整的圆柱状丝素-纳米Fe3O4复合水凝胶。该凝胶具有疏松多孔结构,且孔隙较为规整一致。结构分析表明,各种类型丝素/纳米Fe3O4复合水凝胶中丝素蛋白分子的构象皆以β-折叠为主,晶型以SilkⅡ型为主。力学性能测试表明,增大复合凝胶中丝素含量或纳米Fe3O4含量都可明显提高凝胶的力学强度,而冷冻干燥处理则有助于在保持凝胶微观结构不变的情况下增大凝胶的强度。2. PLLA与PBS溶液共混后相容性良好。共混液的粘度随PLLA含量的增加而增大。共混液经电纺后,得到平均厚度为166μm、直径范围为4-6cm的圆片状复合超细纤维膜。3.研究了电纺工艺参数对PLLA/PBS超细纤维形成,形貌及直径的影响。结果表明,随复合膜中PLLA含量的增加,纤维的平均直径从0.41μm增加到2.16μm,纤维直径的标准差变大,纤维的形貌从珠串状纤维变为平滑纤维,继而又变为含绪丝的粗纤维。随电压的增大,纤维的平均直径先增大后减小,总变化趋势是从0.97μm增大到1.72μm,直径的标准差则先减小后增大。本试验所得复合超细纤维直径的最小值为0.213μm,最大值为7.784μm。4.喷射孔内径为1.2mm时所得纤维表面平滑,形貌较好。接收距离减小,会导致纤维粘连,甚至重新溶解形成薄膜。纺丝液流量加大,致使纯PBS溶液电纺产物变为致密的薄膜结构。可纺出表面平滑,形貌较好,且直径分布相对较窄的PLLA/PBS复合超细纤维的电纺工艺条件为:配比为6;4,电压30kV,喷射孔内径1.2mm,纺丝液流量2.89 mL/h,接收距离17cm,室温室湿。5.不同配比的PLLA/PBS超细纤维膜的红外光谱比较分析及热失重分析表明,复合膜中PLLA与PBS两组分主要以物理共混的状态存在于膜中,膜的热稳定性随材料中PBS含量的增加而明显提高。6.力学性能测试显示,随着复合膜中PLLA含量的增加,薄膜的弹性模量与抗拉强度逐渐增大,延伸率和断裂韧性亦增大。共混比为6:4,电压为25KV时所得复合膜的延伸率最大,电压为30KV时,所得复合膜的断裂韧性最大。PLLA与PBS共混比为8:2时所得电纺膜,具备较高的弹性模量和抗拉强度,同时拥有最高的延伸率和断裂韧性值,为具有最佳强韧性组合的超细复合纤维膜。更多还原

【Abstract】 Biodegradable materials have excellent biocompatibility and physical-chemical properties. It has been extensively applied in the biomedical fields. In this thesis, we fabricated two types of biodegradable materials with natural biodegradable material (silk fibroin) and synthetic biodegradable aliphatic polyester-based materials (Poly(butylene succinate) and Poly(L-lactic acid).Silk fibroin hydrogel is a kind of medical materials with good biodegradability and biocompatibility. It has been widely used as a biomedical material in recent years. Its poor mechanical properties and thermal stability restrict its application in medical field. Therefore, we first fabricated silk fibroin hydrogel reinforced by nano-Fe3O4 particles. By blending nano-Fe3O4 particles with silk fibroin solution, the SF/nano-Fe3O4 composite hydrogel was prepared, and its properties and structures were characterized. A cylindrical SF/nano-Fe3O4 composite hydrogel was obtained. The composite were characterized by high porosity, which were favorable parameters for cell growth and proliferation. Microstructural analysis indicated that fibroin mainly has silk II structure in all types of silk fibroin hydrogel. The mechanical properties of SF/nano-Fe3O4 composite hydrogel were markedly improved with increasing the silk fibroin or nano-Fe3O4 content in the composites.PBS and PLLA are two kinds of synthetic biodegradable materials with good biodegradability and biocompatibility. It has been extensively applied in biomaterial fields. But pure PBS film is frangible and has low biodegradation rate. Meanwhile, PLLA has poor mechanical properties and thermal stability. In order to improve the properties of both PLLA and PBS, we fabricated ultrafine PLLA/PBS fiber non-woven by electrospinning, and studied its properties and structures. Furthermore, the influence of blend ratio, electrostatic voltage, collection distance, aperture of injector nozzle and flow rate on the spinnability of PLLA/PBS solutions and morphology of electrospun PLLA/PBS ultrafine fibers were investigated. An optimal electrospinning condition was obtained in producing uniform cylindrical fibers. The experimental results first showed that the mixture solution of PBS/PLLA has good miscibility, and the viscosity, compatibility and spinnability of the mixture solution increased with increasing the PLLA content. Second, the diameter of PLLA/PBS composite fibers was about 0.213-7.784μm. Along with the viscosity of spinning solution increasing, the composite fibers’ average diameter increased from 0.41μm to 2.16μm, and the standard deviation of average diameter was also increased.Along with the increasing voltage, the composite fibers’ average diameter was first increased and then decreased, but its standard deviation was first decreased and then increased. When the content of PLLA increased, the shape of fiber changed from beaded fibers to smooth fibers, but then high PLLA content made the morphology of the fibers worse. Under the technical parameters of blend ratio of 6:4, voltage of 30kv, needle-orifice of 1.2mm diameter, flow rate of 2.89 mL/h, electrode distance of 17cm, the electrospun ultrafine fibers had narrower diameter distributions and best morphology. FT-IR and TGA analysis indicated that there was no new chemical bond formed between the molecules of PLLA and PBS. The thermal stability of electrospun PLLA/PBS ultrafine fibers was markedly improved with increasing the PBS content in the composites. Mechanical test showed that along with the PLLA content increasing, the elastic modulus and tensile strength of composite film was increased, and the elongation and fracture toughness of film was also increased. When the blend ratio was 8:2, the composite film has the best mechanical properties.更多还原