Stimulus-responsive, Mechanically-dynamic Nanocomposite for Cortical Electrodes

描述（由申请人提供）：皮质电极为大脑的复杂活动提供了一个亲密的接口。它们是一种先进的大脑治疗技术，将显著改善人类的状况，也是研究大脑运作的基本工具。当前技术的限制因素之一是电极和皮质组织之间的机械不匹配。虽然硬电极在植入和定位过程中是有利的，但长期硬电极会导致脑组织中的微运动、微损伤和慢性星形细胞反应。理想的电极在插入时具有高模量，插入后具有低模量。受棘皮动物软结缔组织的启发，我们已经开始探索一种高度创新的新型聚合物纳米复合材料，其目标是动态改变其机械性能，以响应刺激，如温度或pH值变化，电场或光场，或特定离子的浓度。我们建议利用化学刺激（离子浓度或pH值）来形成自适应皮质电极基础的聚合物的机械开关。复合材料力学动态性能的初步可行性已经得到证实。在本提案中，我们将进一步研究它们的性质并开发它们用于生物医学应用。第一个目标是优化成分，以在皮层环境中获得最佳性能。最理想的材料在植入时将在周围环境中保持刚性，并根据皮质的化学环境动态变化，以匹配皮质组织力学。我们将描述机械性能和动力学，以及将材料加工成用于生物应用的设备的基本技术。第二个目标是了解慢性星形细胞和组织对聚合物的反应。该项目的总体目标是创造和理解一种刺激反应，机械动态纳米复合材料，可用于生物医学和神经假肢应用。本提案研究的第一个应用将是作为皮质电极的衬底。

DESCRIPTION (provided by applicant): Cortical electrodes offer an intimate interface to the complex activity of the brain. They are an enabling technology for advanced brain therapies that will significantly enhance the human condition, as well as, fundamental tools for investigating the operation of the brain. One of the limiting factors of current technology is a mechanical mismatch between the electrode and the cortical tissue. While a stiff electrode is advantageous during implantation and positioning, a chronically stiff electrode causes micro-motion, micro-damage, and chronic astrocytic response in the brain tissue. An ideal electrode would have a high modulus during insertion and a low modulus thereafter. Inspired by the soft connective tissues of echinoderms, we have embarked on the exploration of a highly innovative and novel general class of polymer nanocomposites, which are targeted to dynamically change their mechanical properties in response to a stimulus, such as temperature or pH change, electrical or optical field, or concentration of specific ions. We propose to exploit chemical stimuli (ion concentrations or pH) for the mechanical switching of polymers that form the basis of adaptive cortical electrodes. Initial feasibility of the mechanically dynamic properties of the composites have already been demonstrated. In this proposal we will further study their properties and develop them for use in biomedical applications. The first aim is to optimize the composition for optimal performance in the cortex environment. The optimal material will be stiff in an ambient environment and dynamically change in response to the chemical environment of the cortex to match the cortical tissue mechanics when implanted. We will characterize the mechanical properties and dynamics, as well as, the basic techniques processing the material into devices designed for biological applications. The second aim is to understand the chronic astrocytic and tissue response to the polymer. The overall goal of this project is create and understand a stimulus-responsive, mechanically dynamic nanocomposite available for biomedical and neuroprosthetic applications. The first application studied in this proposal will be as a substrate for cortical electrodes.