Gomez Natalia, Lee Jae Y, Nickels Jon D, Schmidt Christine E
Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712-1062 (USA).
Adv Funct Mater. 2007 Jul 9;17(10):1645-1653. doi: 10.1002/adfm.200600669.
Electrically conducting polymers such as polypyrrole (PPy) are important biomaterials in neural engineering applications, including neural probes, nerve conduits, and scaffolds for tissue and nerve regeneration. Surface modification of these polymers can introduce other valuable characteristics for neural interfacing in addition to electrical conductivity, such as topographical features and chemical bioactivity. Here, the patterning of PPy to create topographical cues for cells is reported. In particular, 1 and 2 µm wide PPy microchannels are fabricated using electron-beam (e-beam) lithography and electropolymerization. A systematic analysis of parameters controlling PPy micropatterning is performed, and finds that microchannel depth, roughness, and morphology are highly dependent on the e-beam writing current, polymerization current, PPy/dopant concentrations, and the polymerization time. Embryonic hippocampal neurons cultured on patterned PPy polarize (i.e., defined an axon) faster on this modified material, with a twofold increase in the number of cells with axons compared to cells cultured on unmodified PPy. These topographical features also have an effect on axon orientation but do not have a significant effect on overall axon length. This is the first investigation that studies controlled PPy patterning with small dimensions (i.e., less than 5 µm) for biological applications, which demonstrates the relevance of expanding microelectronic materials and techniques to the biomedical field.
诸如聚吡咯（PPy）之类的导电聚合物是神经工程应用中的重要生物材料，包括神经探针、神经导管以及用于组织和神经再生的支架。这些聚合物的表面改性除了导电性之外，还可以引入其他有价值的神经接口特性，例如形貌特征和化学生物活性。在此，报道了聚吡咯的图案化以创建细胞的形貌线索。具体而言，使用电子束（e-beam）光刻和电聚合制备了宽度为1和2μm的聚吡咯微通道。对控制聚吡咯微图案化的参数进行了系统分析，发现微通道深度、粗糙度和形态高度依赖于电子束写入电流、聚合电流、聚吡咯/掺杂剂浓度以及聚合时间。在图案化聚吡咯上培养的胚胎海马神经元在这种改性材料上更快地极化（即，确定轴突），与在未改性聚吡咯上培养的细胞相比，有轴突的细胞数量增加了两倍。这些形貌特征也对轴突取向有影响，但对轴突的总长度没有显著影响。这是首次研究用于生物应用的小尺寸（即小于5μm）的可控聚吡咯图案化，这证明了将微电子材料和技术扩展到生物医学领域的相关性。
