Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721-0041, United States.
ACS Appl Mater Interfaces. 2011 Jul;3(7):2677-85. doi: 10.1021/am2004637. Epub 2011 Jun 27.
Facilitated ion transport across an artificial lipid bilayer coupled to a solid substrate is a function common to several types of bioelectronic devices based on supported membranes, including biomimetic fuel cells and ion channel biosensors. Described here is fabrication of a pH-sensitive transducer composed of a porous sol-gel layer derivatized with poly(aniline) (PANI) nanowires grown from an underlying planar indium-tin oxide (ITO) electrode. The upper sol-gel surface is hydrophilic, smooth, and compatible with deposition of a planar supported lipid bilayer (PSLB) formed via vesicle fusion. Conducting tip AFM was used to show that the PANI wires are connected to the ITO, which convert this electrode into a potentiometric pH sensor. The response to changes in the pH of the buffer contacting the PANI nanowire/sol-gel/ITO electrode is blocked by the very low ion permeability of the overlying fluid PSLB. The feasibility of using this assembly to monitor facilitated proton transport across the PSLB was demonstrated by doping the membrane with lipophilic ionophores that respond to a transmembrane pH gradient, which produced an apparent proton permeability several orders of magnitude greater than values measured for undoped lipid bilayers.
在与固体基底相连的人工脂质双层中促进离子传输是几种基于支撑膜的生物电子设备（包括仿生燃料电池和离子通道生物传感器）的共同功能。这里描述的是由多孔溶胶-凝胶层组成的 pH 敏感传感器的制造，该层用从下面的平面氧化铟锡（ITO）电极生长的聚（苯胺）（PANI）纳米线进行了修饰。上溶胶-凝胶表面亲水、光滑，并且与通过囊泡融合形成的平面支撑脂质双层（PSLB）的沉积兼容。使用导电尖端原子力显微镜（AFM）表明，PANI 纳米线与 ITO 相连，将该电极转化为电位 pH 传感器。与接触 PANI 纳米线/溶胶-凝胶/ITO 电极的缓冲液的 pH 值变化相关的响应被覆盖层的低离子渗透性流体 PSLB 阻断。通过用响应跨膜 pH 梯度的亲脂性离子载体掺杂该膜，证明了可以使用该组件来监测 PSLB 中促进的质子传输，这产生了比未掺杂脂质双层测量值大几个数量级的表观质子渗透性。
