Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, USA.
ACS Appl Mater Interfaces. 2012 May;4(5):2726-34. doi: 10.1021/am3003632. Epub 2012 May 3.
We report an approach to the rapid release of DNA based on the application of electrochemical potentials to surfaces coated with polyelectrolyte-based thin films. We fabricated multilayered polyelectrolyte films (or "polyelectrolyte multilayers", PEMs) using plasmid DNA and a model hydrolytically degradable cationic poly(β-amino ester) (polymer 1) on stainless steel substrates using a layer-by-layer approach. The application of continuous reduction potentials in the range of -1.1 to -0.7 V (vs a Ag/AgCl electrode) to film-coated electrodes in PBS at 37 °C resulted in the complete release of DNA over a period of 1-2 min. Film-coated electrodes incubated under identical conditions in the absence of applied potentials required 1-2 days for complete release. Control over the magnitude of the applied potential provided control over the rate at which DNA was released. The results of these and additional physical characterization experiments are consistent with a mechanism of film disruption that is promoted by local increases in pH at the film/electrode interface (resulting from electrochemical reduction of water or dissolved oxygen) that disrupt ionic interactions in these materials. The results of cell-based experiments demonstrated that DNA was released in a form that remains intact and able to promote transgene expression in mammalian cells. Finally, we demonstrate that short-term (i.e., non-continuous) electrochemical treatments can also be used to promote faster film erosion (e.g., over 1-2 h) once the potential is removed. Past studies demonstrate that PEMs fabricated using polymer 1 can promote surface-mediated transfection of cells and tissues in vitro and in vivo. With further development, the electrochemical approaches reported here could thus provide new methods for the rapid, triggered, or spatially patterned transfer of DNA (or other agents) from surfaces of interest in a variety of fundamental and applied contexts.
我们报告了一种基于施加电化学势到涂覆聚电解质基薄膜的表面来快速释放 DNA 的方法。我们使用质粒 DNA 和模型可水解的阳离子聚（β-氨基酯）（聚合物 1）在不锈钢基底上使用层层自组装的方法制备了多层聚电解质薄膜（或“聚电解质多层”，PEMs）。在 37°C 的 PBS 中，将连续的还原电势施加到涂覆有薄膜的电极上，范围为-1.1 至-0.7 V（相对于 Ag/AgCl 电极），导致 DNA 在 1-2 分钟内完全释放。在相同条件下孵育但未施加电势的涂覆有薄膜的电极需要 1-2 天才能完全释放。施加电势的幅度的控制提供了对 DNA 释放速率的控制。这些结果和其他物理特性实验的结果与一种膜破坏机制一致，该机制是由膜/电极界面处 pH 值局部升高（由于电化学还原水或溶解氧所致）促进的，该升高破坏了这些材料中的离子相互作用。基于细胞的实验结果表明，DNA 以保持完整的形式释放，并能够促进哺乳动物细胞中的转基因表达。最后，我们证明，一旦去除电势，短期（即非连续）电化学处理也可用于促进更快的薄膜侵蚀（例如，在 1-2 小时内）。过去的研究表明，使用聚合物 1 制备的 PEMs 可以促进细胞和组织的表面介导转染，无论是在体外还是在体内。随着进一步的发展，这里报道的电化学方法可以为在各种基础和应用背景下从感兴趣的表面快速、触发或空间图案化地转移 DNA（或其他试剂）提供新方法。
