Langmuir. 2020 Sep 22;36(37):11034-11043. doi: 10.1021/acs.langmuir.0c01894. Epub 2020 Sep 13.
Using electrical signals to guide materials' deposition has a long-standing history in metal coating, microchip fabrication, and the integration of organics with devices. In electrodeposition, however, the conductive materials can be deposited only onto the electrode surfaces. Here, an innovative process is presented to electrofabricate freestanding biopolymer membranes at the interface of electrolytes without any supporting electrodes at the fabrication site. Chitosan, a derivative from the naturally abundant biopolymer chitin, has been broadly explored in electrodeposition for integrating biological entities onto microfabricated devices. It is widely believed that the pH gradients generated at the cathode deprotonate the positively charged chitosan chains into a film on the cathode surface. The interfacial electrofabrication with pH indicators, however, demonstrated that the membrane growth was driven by the instantaneous flow of hydroxyl ions from the ambient alginate solution, rather than the slow propagation of pH gradients from the cathode surface. This interfacial electrofabrication produces freestanding membrane structures and can be expanded to other materials, which presents a new direction in using electrical signals for manufacturing.
利用电信号引导材料沉积在金属涂层、微芯片制造以及有机材料与器件的集成方面有着悠久的历史。然而，在电沉积中，只能将导电材料沉积到电极表面上。在这里，提出了一种创新的工艺，即在没有任何支撑电极的情况下，在电解质的界面处电纺制独立的生物聚合物膜。壳聚糖是一种从天然丰富的生物聚合物甲壳素衍生而来的物质，它已被广泛探索用于将生物实体集成到微制造设备中。人们普遍认为，在阴极处产生的 pH 梯度将带正电荷的壳聚糖链去质子化为阴极表面上的膜。然而，带有 pH 指示剂的界面电纺丝表明，膜的生长是由来自周围海藻酸盐溶液的羟基离子的瞬时流动驱动的，而不是由从阴极表面缓慢传播的 pH 梯度驱动的。这种界面电纺丝可产生独立的膜结构，并可扩展到其他材料，为利用电信号制造提供了新的方向。
