基于石墨烯的植入式神经电极生物相容性和稳定性的研究

Neural electrical stimulation is a new technology in the treatment of neurological disease. One major problem that affects clinical applications of neural electrical stimulator is the decreased performance of implantable neural electrodes after long-term implantation. Development of biocompatible and stable neural electrode coating materials is expected to solve this problem. Although electrodeposited conducting polymers have good biocompatibility, their poor long-term stability, especially the adhesive force with the substrate, hinders their applications. In our previous work, carbon nanotubes, which is a cylinder structure of graphene, was incorporated into the conducting polymer as a neural electrode coating material. And the results showed that this composite material has better biocompatibility, but its long term stability still needs to be improved. It’s reported that the graphene deposited on the metal surface by chemical vapor deposition has strong adhesive force with the substrate, which is expected to solve the problem of adhesion between the electrode coating material and the substrate. In this study, graphene was deposited on the surface of neural electrode by chemical vapor deposition and its electrochemical performance, long-term stability and biocompatibility were evaluated by electrochemical methods, cell culture and immunohistochemical staining methods, in order to explore a new electrode coating material.

神经电刺激是治疗神经系统疾病的一种新兴技术，目前制约神经电刺激器临床应用的一个主要问题是神经电极长期植入后其性能下降，发展具有良好生物相容性和稳定性的神经电极修饰材料有望解决这一难题。目前国内外多采用电沉积导电聚合物作为神经电极的修饰材料，虽然具有良好的生物相容性，但是由于其长期稳定性，特别是粘附性欠佳，制约了其应用。申请人前期研究发现，采用电化学共沉积制备的导电聚合物和碳纳米管(由石墨烯卷曲而成的圆筒结构)的复合材料作为电极的修饰材料，具有更好的生物相容性，但依然存在长期稳定性不佳的问题。而通过化学气相沉积的方法沉积在金属表面的石墨烯与基底之间存在很强的粘合力，有望解决电极修饰材料与基体之间的粘附问题。本课题拟在前期研究的基础上，采用化学气相沉积的方法制备石墨烯修饰的神经电极，结合电化学、细胞培养和免疫组织化学等方法，评价其电化学性能、机械稳定性以及生物相容性，寻找新的神经电极修饰材料。

神经假体是治疗神经系统疾病的一种新兴技术，目前制约神经假体临床应用的一个主要问题是神经电极长期植入后其性能下降，发作具有良好生物相容性和稳定性的神经电极修饰材料有望解决这一难题。本研究采用电化学沉积的方法，以氧化石墨烯（GO）作为掺杂子，合成了一种新型的导电聚合物材料—PEDOT/GO，探讨其作为神经电极修饰材料的可能性。结果显示PEDOT/GO较传统的材料PEDOT/pTS具有更好的电化学稳定性，细胞相容性可以与PEDOT/pTS媲美，但是机械性能不如PEDOT/pTS。在接下来的研究中，我们将水凝胶引入到导电聚合物的合成中，合成了一种新的材料-导电水凝胶，导电水凝胶的电荷储存量（CSC）不及传统的导电聚合物（PEDOT/pTS），但是其电化学稳定性很稳定，在经过800个氧化-还原循环之后，导电水凝胶损失的的电荷储存量不到5%。并且，由于引入了水凝胶的缘故，导电水凝胶的机械性能较传统的导电聚合物有明显的提升，因此，导电水凝胶适合用作神经电极的修饰材料。