Electrode optimization for neuroprostheses

为了进一步发展植入式神经假体，必须使用具有最佳电化学性能的柔软和生物相容性材料。因此，这个项目的目的是使用基于有机大分子的聚合物来增强神经假体的电极。这将通过三个模块来实现，这些模块结合了材料科学和生物学角度的新方法：利用金属纳米颗粒制备电化学吸引聚合物，这些聚合物的表面微结构，以及在适当的细胞培养系统中神经活动的生物学演示。这三个模块的结合为神经修复提供了一种独特的方法。实现计划如下：为了满足电化学需求，将商用电极材料铂与本质导电（聚3,4-乙基二氧噻吩：PEDOT）和非导电（有机硅、聚二甲基硅氧烷：PDMS、聚氨酯TPU）聚合物进行比较。PDMS和TPU的导电性将通过添加纳米复合材料，如金、铁、铂纳米颗粒和碳纳米管及其组合来实现。适当的表面微结构（微米尺度上的大面积尖峰和凹槽结构）将支持细胞粘附和神经突的最佳排列，这将在所谓的负复制技术的帮助下实现，该技术允许将激光生成的主结构互补地复制到软材料中。导电材料及其微结构的生成将伴随着材料优化的广泛技术分析。神经元活动和细胞粘附（由外至内的信号级联）的生物学论证将通过计划中的人间充质干细胞体外研究来进行，因为细胞系的价值有限，而且很难获得原代人神经细胞。间充质干细胞受材料特性控制，具有神经元分化的内在潜能。为了测试所生产材料的有效性，将进行细胞生物学、分子生物学和电生理学分析。这将有助于证明材料将增强细胞的神经元发育以及它们在神经元网络方面的相互连接，这将得到原理证明的支持-使用来自下丘的神经元的体外实验。这些研究将为今后的临床应用奠定基础。

For further development of implantable neuroprostheses electrodes soft and biocompatible materials with optimal electrochemical properties have to be used. Aim of this project therefore is to use polymers based on organic macromolecules for an enhancement of electrodes for neuroprostheses. This shall be achieved through three modules which incorporate novel approaches both from the material science and biological point of view: the preparation of electrochemically attractive polymers by use of metallic nanoparticles, surface microstructuring of these polymers, and the biological demonstration of neuronal activities in appropriate cell culture systems. The combination of these three modules presents a unique approach in neuroprosthetics. The realization is planned as follows:To meet electrochemical needs, the commercially electrode material platinum will be compared with intrinsically conducting (poly-3,4-ethylendioxythiophene: PEDOT) and non-conducting (silicone, polydimethylsiloxane: PDMS, polyurethane TPU) polymers. The conductance of PDMS and TPU will be achieved by the addition of nanocomposites such as gold-, iron-, platinum-nanoparticles and carbonnanotubes and a combination of them. Appropriate surface microstructuring (large area spikes and grooves structures on micrometer scale), which will support cell adhesion and an optimum alignment of neurites, shall be realized with the help of the so-called negative replication technique which allows for a complementary reproduction of laser-generated master structures into soft materials. The generation of conducting materials and their microstructuring will be accompanied by extensive technical analyses for material optimization.The biological demonstration of neuronal activities and cell adhesion (outside-in signaling cascades) will be performed by in vitro studies planned with human mesenchymal stem cells since cell lines are of limited value and primary human nerve cells are hardly available. Mesenchymal stem cells can be controlled by material properties and have an inherent potential for neuronal differentiation. To test the effectiveness of the produced materials cell biological, molecular biological and electrophysiological analyses will be performed. This will serve to demonstrate that the materials will enhance the neuronal development of the cells and also their interconnection in terms of a neuronal network, which will be supported by a proof of principle-experiment in vitro using neurons from the Colliculus inferior. These studies will serve as basis for future clinical applications.