Polymers and Fiber Surfaces

制备梯度植入物的起点是聚己内酯(PCL)静电纺丝制备的纤维垫。该项目的目标是，以一种适合药物释放系统功能化的方式对纤维垫进行改性。为此，纤维垫用等离子体处理，涂上聚多巴胺(PDA)或壳聚糖-接枝-聚己内酯(CHI-g-PCL)。在最后一次资助期间，这三种方法已被证明适合于将纤维垫与药物释放系统一起功能化，并产生空间梯度。然而，不同的修改所获得的结果是不同的。结果表明，与CHI-g-PCL相比，PDA改性的纤维垫可以吸附更多的纳米多孔二氧化硅纳米粒子作为药物释放系统。然而，与CHI-g-PCL修饰的纤维垫相比，PDA修饰的纤维垫上的聚合物药物释放系统释放的信号蛋白更少。应系统地研究这些差异以及各种改进方法的优缺点。此外，它们还应归因于表面的化学和物理性质。为此，将使用相同的药物释放系统(由子项目TP5提供)对不同改性的纤维垫进行功能化，并将研究释放动力学(与子项目TP6一起)。结果将与改性纤维垫的表面电位(Zeta电位)相关联，这可以通过电动测量来确定。除了可以用纤维表面、药物释放系统和蛋白质的Zeta电位来定量的静电相互作用外，还将考虑疏水相互作用。为此，将使用模型蛋白质进行蛋白质吸附测量。对静电和疏水相互作用的透彻了解将使基于知识的纤维垫的最佳改性设计成为可能。这也将允许将该方法转移到其他生物医学应用中。首先，将进行将涂层方法转移到其他基材上的测试。将PCL与不同的PCL-嵌段和接枝共聚物进行共混，并作为共混物进行电纺。通过这种方式，在表面引入更多化学官能团的进一步方法可以在必要时用于改善细胞粘附性。应使用与光反应共聚物的混合来调整纤维的性能(连同子项目TP3)。

The starting point for the preparation of graded implants are fiber mats prepared by electrospinning of polycaprolacton (PCL). Aim of this project is, to modify the fiber mats in a way that they will be suited for the functionalization with drug release systems. To do so, the fiber mats are treated by plasma, coated with polydopamin (pDA) or with chitosan-graft-polycaprolacton (Chi-g-PCL). In the last grant period these three methods have been proven to be suitable to functionalize fiber mats with drug release systeme and to create spatial gradients. However, the different modifications differ in the results obtained. It was found that more nanoporous silica nanoparticles as drug release system could be adsorbed by the pDA modified fiber mats compared to those modified with Chi-g-PCL. However, less signaling protein was released from polymeric drug delivery systems on fiber mats modified with pDA compared to fiber mats modified with Chi-g-PCL. These differences and with that the advantages and disadvantages of the modification methods shall be investigated systematically. In addition they shall be ascribed to chemical and physical surface properties. To do so the differently modified fiber mats will be functionalized with the same drug release system (supplied by subproject TP5) and the release kinetics will be investigated (together with subproject TP6). The results will be correlated with the surface potential (zeta-Potential) of the modified fiber mats, which can be determined by electro-kinetic measurements. Besides the electrostatic interactions which can be quantified using the zeta potentials of the fiber surfaces, the drug release system and the proteins, also hydrophobic interactions will be taken into account. For this, protein adsorption measurements with model proteins will be carried out. A thorough understanding auf the electrostatic and hydrophobic interactions will enable a knowledge-based design of an optimal modification of the fiber mats. This will also will allow a transfer of the method to other biomedical applications. First tests to transfer the coating methods to other substrates will be carried out. Blending of PCL with different PCL-block- and graft-copolymers will be prepared and electro spun as blend. In this way, further methods to introduce further chemical functionalities at the surface which can be used to improve cell adhesion if necessary. Blending with photo-reactive copolymers shall be used to adjust the properties of the fibers (together with subproject TP3).