Fabrication of electrospun fibre mats with defined geometry and load profile

子项目3（SP3）的重点是通过静电纺丝从聚己内酯（PCL）制造纤维毡。这些纤维垫应具有分级的机械和几何特性，并且必须承受天然负载条件。用于大鼠或绵羊体内研究的制造纤维垫的方法遭受支架的不适当的机械性能。这个问题将在第二个资助期通过将溶液电纺与熔体电纺相结合来解决。这种组合允许制造具有适当机械性能的较大纤维尺寸。它能够制造具有承重结构的支架，该承重结构与模拟天然细胞外基质的结构相结合以增强细胞浸润。由此产生的支架由微米和纳米纤维的组合组成，这增加了比表面积。已知比表面影响细胞附着，这将在SP 1中进行研究。将通过原子力显微镜（AFM）测量BM-MSC的细胞粘附力。第一个资助期的研究表明，聚合物的结晶度是对机械性能具有高度影响的因素之一（SP 4的结果）。结晶度可以通过改变收集器的旋转速度来影响。它随着速度的增加而增加。这种效果以及与壳聚糖-g-聚己内酯（SP 4）的共混将用于在下一个资助期内定制支架的机械性能。此外，将与SP 6合作研究降解动力学。在此，将分析质量损失以及分子结构的变化（拉曼光谱），以进一步研究降解过程。 该子项目的工作计划将产生一个脚手架，该脚手架适合小型和大型动物的负载条件。在动物试验中评估该支架的性能（SP 8）。

Subproject 3 (SP3) focuses on the fabrication of fiber mats from polycaprolactone (PCL) via electrospinning. These fiber mats should have graded mechanical and geometric properties as well as have to withstand the native loading conditions. Approaches to fabricate fiber mats for in vivo studies in rats or sheep suffered from inappropriate mechanical properties of the scaffold. This issue is going to be solved in the second funding period by combining solution electrospinning with melt electrospinning. This combination allows for the fabrication of larger fiber sizes with appropriate mechanical properties. It enables the fabrication of scaffolds with load-bearing structures combined with structures mimicking the native extracellular matrix to enhance cell infiltration. The resulting scaffolds consists of a combination of micro- and nanofibers, which increases the specific surface. The specific surface is known to influence cell attachment, which is going to be investigated in SP 1. Cell adhesion forces of BM-MSCs will be measured via atomic force microscopy (AFM). Studies in the first funding period have shown the crystallinity of the polymer being one of the factors with high impact on the mechanical properties (results of SP4). The crystallinity can be influenced by changing the rotating velocity of the collector. It increases with increasing velocity. This effect as well as the blending with chitosan-g-polycaprolactone (SP4) will be used to tailor the mechanical properties of the scaffold during the next funding period. In addition, the degradation kinetics will be investigated in cooperation with SP 6. Here, mass loss as well as changes in the molecular structure (Raman spectroscopy) will be analyzed to further investigate the degradation process. The working plan of this subproject will result in a scaffold, which is tailored to the loading conditions in small and large animals. The performance of this scaffold is assessed in animal trials (SP8).