Electrode optimization for neuroprostheses

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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.