电刺激控制联合释放Dex与NGF的三维神经电极材料的研究

Brain tissue response and loss of neurons around implanted electrodes are currently main reasons restricting the development and clinical applications of neural prosthetics. Common methods to control brain tissue response or stimulate neuron growth around the implanted electrode is local release of anti-inflammatory drugs or neural growth factors. In our previous studies, it was found that surface modification of neural electrode with three dimensional (3D) conductive biofilms greatly improved electrodes' electrochemical performance and stability, and promoted the growth and differentiation of neural cells. This project is designed to develop local controllable release systems of both anti-inflammatory drugs-dexamethasone (Dex) and nerve growth factor (NGF) based on 3D conductive biofilms. Their anti-inflammatory and anti-brain tissue response activity, as well as effects on neural cell growth and differentiation will be evaluated from in vitro and in vivo experiments, and finally determine the role of joint Dex and NGF on improvement of implanted neural electrode performance and the best embedding method. This project is the novel attempt to combine Dex and NGF in the area of neural electrode modification, aiming to reduce brain tissue response and stimulate the growth of neural cells around implanted electrodes at the same time. The finish of this project will provide theoretical basis for the development of novel neural electrodes, and provide new ideas for electrical stimulation treatment of nerve injury disease.

组织反应与电极周围神经元丢失是目前神经假体技术发展与临床应用的瓶颈问题，局部释放抗炎药物或神经促生长因子是抑制组织反应或促进神经细胞生长的常用方法，但效果不理想。申请人前期研究发现基于导电高分子的三维导电生物膜可显著提高电极的电化学性能和稳定性，促进神经细胞生长和分化，本项目拟在三维导电生物膜中联合包埋抗炎药物地塞米松（Dex）和神经生长因子（NGF），建立局部电刺激可控释放体系，并通过体外和体内实验分析功能化导电生物膜修饰神经电极的抗炎和抗组织反应能力及对神经细胞生长与分化的诱导作用，最终确定联合Dex与NGF在提高神经电极性能中的作用及最佳包埋方法。本项目为联合抗炎药物和神经促生长因子在神经电极研究领域的创新尝试，旨在降低组织反应的同时诱导电极周围神经细胞的生长与分化，建立高整合度电极-神经细胞界面，为新型神经电极的开发提供依据，为神经损伤疾病电刺激治疗提供新思路。

本项目针对局部释放抗炎药物或神经促生长因子以解决组织反应与电极周围神经元丢失的常用方法效果不理想问题，开展电刺激联合释放抗炎药物地塞米松(Dex)和神经生长因子(NGF)三维(3D)神经电极材料的研究。通过项目的实施，成功制备了多孔性纳米结构聚噻吩(PEDOT)、PEDOT纳米管阵列、碳纳米管(CNT)/聚吡咯(PPy)层叠结构三种导电生物膜，与未修饰电极相比，这些导电生物膜修饰的神经电极的电荷存储密度提高了2个数量级，在1 kHz频率处的界面阻抗降低了2个数量级。以这些3D导电生物膜为基础建立了3种电刺激控制Dex释放体系和1种电刺激控制联合释放Dex和NGF的功能化导电生物膜体系，FT-IR分析确定了Dex、NGF的成功包埋。除显著提高电极的电荷存储密度和降低界面阻抗外，所建立的功能化导电生物膜能在更短的时间释放比常用PPy/Dex体系更多的Dex，且能持续更久的时间。生物相容性试验发现，功能化导电生物膜的电刺激释放液对RAW264.7细胞、PC12细胞和大鼠原代脑皮层神经细胞的活性无明显影响，且能有效降低脂多糖(LPS)刺激RAW264.7细胞的炎症因子(TNF-α、IL-1β、IL-6和IL-8)的分泌；培养于联合包埋Dex和NGF功能化导电生物膜上的PC12细胞，比培养于ITO玻璃上的细胞有更多和更长的轴突。此外，培养于联合包埋Dex和NGF功能化导电生物膜上的大鼠脑皮层细胞中，反应性星形细胞的数量较培养于ITO玻璃表面的更少，神经细胞数量更多，具有的更多更长的神经轴突。因此，在3D导电生物膜中联合包埋Dex和NGF在显著提高电极的电荷存储密度、降低界面阻抗的同时，可抑制炎症反应、减轻组织反应、促进神经细胞的生长。