叠层介孔导电凝胶多选择性氧化还原体系及体内能量转换的研究

Making full use of the in vivo glucose conversion and storage of electrical energy to provide implanted medical devices and electroactive biomaterials with long-term, secure and stable electricity is of great significance for biomaterials in clinical. In this study, a mesoporous nano-silver/gel cathode membrane electrode of high electrochemical activity was prepared based on the structural design of laminated porous conductive gel multi-selective redox energy conversion device prototype. Further experiment was carried out to explore catalytic oxygen reduction reaction conditions of the electrode in the existence of glucose. Meanwhile, we established the control mechanism and model of the selective permeation and diffusion process of a variety of biomolecules. A gradient porous structure of activated nano-carbon/catalyst/gel anodic film electrode was prepared and researched to reveal its effects on the selective electrochemical catalytic activity and electron mobility of several reductants in physiological environment. Besides, conductive hydrogel's negative resistance effects and mechanism on the anode electronic storage and electron mobility increase were explored. Finally, in situ integration of laminated manufacturing process was applied to manufacture the overall structure of cathode film/electrolyte film/anodic film energy conversion device prototype. Electrode potential, current density and output power results in a simulated physiological environment, as well as biological safety evaluations of the system and reaction products were investigated in the project. It is anticipated this research will provide experimental basis and data for applications of energy conversion devices implanted in vivo.

利用体内小分子转化和储存电能为植入的医疗器械和电活性生物材料提供长期安全稳定的电场对其临床应用有重要意义。本项目首先设计了新型叠层介孔导电凝胶多选择性氧化还原型体内能量转换器件原型结构，并制备高电化学活性的介孔纳米银/凝胶态阴极膜电极，研究其在葡萄糖存在的条件下催化氧的还原反应条件，同时建立其对多种生物分子的选择性透过和扩散过程控制机理和模型；其次研究和制备梯度介孔结构活化纳米碳/催化剂/凝胶态阳极膜电极，揭示其对生理环境中几种还原剂选择性电化学催化活性和电子迁移的影响关系和规律；并探讨膜电极的负电阻效应对阳极电子储存和提高电子迁移率的作用和相关机理；最后采用原位一体化叠层制备工艺，构建阴极膜/电解质膜/阳极膜的整体结构能量转换器件原型，研究其在模拟生理环境中的电极电势、电流密度和输出功率，并对体系和反应产物进行生物安全性评价，为植入体内能量转换器件的应用提供实验基础和数据。

生物安全性高、性能长期稳定且结构简单可控的体内能量转换器件是国内外的研究热点，本课题通过对高电化学活性的新型介孔/多孔阴极膜电极、阳极膜电极和凝胶态聚电解质的结构设计、基体和催化材料体系选择、原位合成和微观形貌控制等，系统研究比较了不同电极膜的电化学活性、电子-离子导电性、体内选择性催化特性和生物相容性，进而设计和组装了具有选择性催化功能和高活性和稳定性的植入体表层非生物催化葡萄糖燃料电池，并建立了相应材料体系的化学和结构参数对其电子-离子传递和电化学活性的影响关系和机理，解决了目前葡萄糖电池存在阴极氧还原催化材料制备工艺复杂、体内易失活、多孔阳极膜电活性和选择性差、 生物相容性差、以及体内各成分共混造成电化学短路等难以满足在体内安全使用等问题，为有源医疗器械体内自供电体系的应用提供了有价值的实验数据和理论基础。.课题取得以下重要的研究结果：（1）采用原位还原法合成了AgNP/BC复合阴极膜，其氧还原催化反应是电极表面反应与扩散传质混合控制过程的准可逆反应体系，以4e-为主导，2e-和4e-混合的氧还原路径，电子转移数n=3.8；体液成分和多种生物大分子对于AgNP/BC氧还原催化活性有一定的影响，但在正常体液的浓度范围时仍能保持良好的氧还原活性。（2）分别对BC进行活化改性，得到高离子活性的羧甲基化、羧酸化以及磺化BC，并以此为模板原位合成聚苯胺凝胶聚电解质膜，离子电导率高达10-3 S/cm，同时具有良好的热稳定性、力学性能、稳定的电化学窗口及优异的生物相容性。（3）采用超声辅助电泳沉积并结合原位还原工艺，制备PVA基和BC基的系列凝胶阳极膜，其中纳米铂/碳纳米管/BC复合电极膜具有纳米铂均匀稳定分布的拓扑网络结构，在富氧模拟体液中对葡萄糖选择性催化；利用该阳极膜设计了植入体表层葡萄糖燃料电池，可克服葡萄糖和溶解氧共存带来的混合电动势；调控电极膜的结构参数等，实现模拟体液中电池的功率密度可达到2 μW/cm2；同时具有良好的生物相容性。