Diamond-based Platforms for Long-term Growth and Investigations of Neurons

神经科学的最新发展对用于研究完全组织的神经网络及其活动的材料和设备的特性和功能产生了不断增长的需求。它们应该在不应用细胞外基质蛋白的情况下提供良好和快速的神经元附着，并且不应该随着与生物系统接触的时间而降解，从而允许长期测量。薄膜形式的金刚石由于其杰出的机械、光学、电学、化学和生物特性而成为这类应用的前景候选者。本研究计划旨在制备基于超晶金刚石（UNCD）薄膜的平台，用于功能性神经元网络的长期生长及其电生理研究。由金刚石纳米晶（约5 nm）嵌入无定形碳基体组成的UNCD薄膜，结合了金刚石的优异性能和相当光滑的形貌，并包含纳米结构，这将增强神经元的快速和良好的粘附性。在这项工作中，多层超晶金刚石和金属结构将沉积在玻璃基板上，其透明度允许从背面对定位在平台上的神经元进行显微镜观察，并结合从顶部进行荧光成像。下一步，从这些层开始，用于记录神经元活动的金属轨迹和用于神经元接触垫的UNCD将采用光刻和蚀刻技术进行结构。由于表面在与细胞的相互作用中起着极其重要的作用，因此将应用等离子体或光化学过程对UNCD表面进行各种修饰，然后对表面终止进行图图化。为了研究层系统的生物相容性和功能，我们将使用蟑螂Rhypharobia maderae的起搏器神经元和烟草角虫Manduca sexta的嗅觉受体神经元两种类型的神经元，这两种类型的神经元分别作为研究发育中的神经元网络的自发电活动和定向生长的模型，这两种类型的神经元都是长期的研究，目前还没有用其他材料实现。

The recent development of neurosciences creates an ever increasing demand to the properties and functionalities of materials and devices used for the study of fully organized neuronal networks and their activity. They should provide good and fast attachment of the neurons without the application of extracellular matrix proteins and should not degrade with the time upon contact with the biological system thus allowing long-term measurements. Diamond in the form of thin films is a perspective candidate for such applications due to its outstanding mechanical, optical, electrical, chemical, and bio-properties. This research proposal aims at the preparation of platforms based on ultrananocrystalline diamond (UNCD) films for the long-term growth of functional neuronal networks and their electrophysiological investigations. The UNCD films which are composed of diamond nanocrystallites (ca. 5 nm) embedded in amorphous carbon matrix combine the extreme diamond properties with a rather smooth topography and include nanostructures which will enhance the fast and good adhesion of the neurons. During this work multilayers of ultrananocrystalline diamond and metal structures will be deposited on glass substrates with a transparency allowing the microscopical observation of the neuron positioned on the platforms from the backside combined with, for example, fluorescence imaging from the top. As a next step, from these layers the metal tracks for recording the neuron activity and the UNCD for the contact pads for the neurons will be structured applying lithography and etching. Since the surface plays an extremely important role in the interactions with cells various modifications of the UNCD surface by plasma or photochemical processes will be applied, followed by patterning of the surface termination. For the investigation of the biocompatibility and functionality of the layer systems two types of neurons will be used, namely pacemaker neurons of the cockroach Rhypharobia maderae and olfactory receptor neurons from the tobacco hornworm Manduca sexta which serve as models for the investigation of the spontaneous electrical activity and the directional growth of developing neuronal networks, respectively, both aiming at long-term studies, not achieved till now with other materials.