微米级大孔径丝素复合纳米纤维支架的制备及性能研究

发布时间：2018-01-17 00:04

本文关键词：微米级大孔径丝素复合纳米纤维支架的制备及性能研究　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：静电纺丝纳米纤维支架在纤维尺寸和结构上与生物细胞生长环境的细胞外基质(ECM)较相似,因此在皮肤、软骨、角膜、神经等组织工程领域有广泛的应用,但静电纺纳米纤维支架内纤维排列紧密、纤维之间的空隙过小,使得细胞难以长入,无法构成较厚的细胞组织。本文利用静电纺丝技术,结合材料牺牲法、负电压收集着重研究对纳米纤维支架厚度、孔径和空隙率的影响,制备出接近细胞尺寸的微米级大孔径纳米纤维支架。本文选择浓度为20wt%的PEG的氯仿溶液作为静电喷雾溶液,该浓度下的溶液中的PEG大分子链处在半稀溶液中度缠结体系范围内,在该缠结体系内获得静电喷雾PEG微球的形貌最稳定,且可用于静电喷雾的电喷流率调节范围也比较大,在流率为4 mL/h以下都能收集到形貌稳定的PEG微球。结果表明在条件下可以制备出直径10微米左右水溶性PEG微球,且在不同的静电喷雾流率下都可以获得尺寸、形貌稳定的PEG微球。结合材料牺牲法,运用滚筒接收装置收集混杂静电喷雾PEG微球的SF/Gelatin纳米纤维复合支架,调整静电喷雾的流率来控制复合纳米纤维支架中PEG微球的含量制备出不同孔径及孔隙率规格的复合纳米纤维支架;之后通过水洗去除掺杂在纳米纤维支架中水溶性PEG微球,进一步增大复合纳米纤维支架的孔径及孔隙率;当PEG微球含量较高时,洗去的PEG微球后复合纳米纤维支架平均孔径可以达到20μm以上,但电纺支架的力学强度会随着PEG含量的提高而显著下降。为了提高纳米纤维支架的厚度和孔径,改用自制有机玻璃板结合金属铜板收集装置并连接负电压电源有效减小静电纺丝收集的面积,在针头处连接+15 kV高压电源并在圆形铜板处连接负高压电源可以制备出3 mm厚的SF/PCL纳米纤维支架;建立坐标系,分析针头与圆形金属板中心之间和PMMA平板上的电场分布情况,探索出在接近圆孔收集板处电场强度显著提高,使纤维受到向外扩散时间和电场力也减少,导致纳米纤维更多集中往连接负电压的圆孔处靠拢;最后利用样品截面SEM照片分析孔径,得出超厚纳米纤维支架的孔径随纳米纤维支架厚度增加而变大,当厚度d600μm时,其厚度区域内的纳米纤维支架的孔径可以达到25μm以上。
[Abstract]:Electrostatic spinning nanofiber scaffolds are similar in size and structure to ECM in the living cell environment, and therefore in the skin, cartilage, and cornea. Nerve and other tissue engineering fields have been widely used, but the fibers in the scaffold of electrospun nanofibers are tightly arranged and the gap between the fibers is too small, which makes it difficult for cells to grow into the scaffold. In this paper, the effect of negative voltage collection on the thickness, pore size and porosity of nanofiber scaffolds was studied by using electrospinning technique and material sacrificial method. Micron sized nano-fiber scaffolds of near cell size were prepared. Chloroform solution of PEG with concentration of 20 wt% was selected as electrostatic spray solution in this paper. The PEG macromolecular chains in the solution at this concentration are in the range of degree entanglement in semi-dilute solution, and the morphology of electrostatic sprayed PEG microspheres is the most stable in the entangled system. And the range of EFI rate can be used for electrostatic spray is also relatively large. The PEG microspheres with stable morphology can be obtained when the flow rate is less than 4 mL/h. The results show that the water-soluble PEG microspheres with a diameter of about 10 microns can be prepared under the conditions. PEG microspheres with stable size and morphology can be obtained under different electrostatic spray flow rates. The SF/Gelatin nanofiber composite scaffold with hybrid electrostatic sprayed PEG microspheres was collected by drum receiving device. Adjusting the flow rate of electrostatic spray to control the content of PEG microspheres in composite nanofiber scaffold, the composite nanofiber scaffolds with different pore sizes and porosity specifications were prepared. After that, the water-soluble PEG microspheres doped in the nanofiber scaffold were removed by washing to further increase the pore size and porosity of the composite nanofiber scaffold. When the content of PEG microspheres is high, the average pore size of the composite nanofiber scaffolds after washing PEG microspheres can reach more than 20 渭 m. However, the mechanical strength of electrospun scaffolds will decrease with the increase of PEG content, in order to increase the thickness and pore size of nano-fiber scaffolds. Using self-made plexiglass plate combined with metal copper plate collecting device and connecting negative voltage power supply can effectively reduce the area of electrostatic spinning collection. The 3mm thick SF/PCL nanofiber scaffold can be fabricated by connecting the 15 kV high voltage power supply at the needle and the negative high voltage power supply at the circular copper plate. The electric field distribution between the needle and the center of the circular metal plate and on the PMMA plate was analyzed in the coordinate system, and the electric field intensity was significantly increased near the circular hole collecting plate. The diffusion time and electric field force of the fibers are also reduced, which leads to more concentration of the nanofibers towards the round holes connected with negative voltage. At last, the pore size of ultra-thick nanofiber scaffold was analyzed by SEM photographs of the sample section, and the pore size increased with the increase of the thickness of nano-fiber scaffold, when the thickness of nano-fiber scaffold was 600 渭 m. The pore size of nanofiber scaffold in its thickness region can reach more than 25 渭 m.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R318.08;TQ340.64

【相似文献】