材料科学
纳米技术
频道(广播)
脂质双层
双层
纳米孔
离子流
离子通道
光电子学
离子
化学
膜
计算机科学
电信
生物化学
受体
有机化学
作者
Essraa A. Hussein,Raymond P. White
标识
DOI:10.1021/acs.jpcb.2c06275
摘要
Ion channel proteins showed great promise in the field of nanopore sensing and molecular flux imaging applications due to the atomic-level precision of the pore size and a high signal-to-noise ratio. More specifically, ion channel probes, where the protein channels are integrated at the end of a solid probe, can achieve highly localized detection. Metal probe materials such as gold and silver have been developed to support lipid bilayers and enable the use of smaller probes, or nanoneedles, compared to more traditional glass micropipette ion channel probes. Silver probes are preferable because they support sustained DC stable channel current due to the AgCl layer formed around the tip during the fabrication process. However, one of the current challenges in ion channel measurements is maintaining a single-channel recording. Multiple protein insertions complicate data analysis and destabilize the bilayer. Herein, we combine the promising probe material (Ag/AgCl) with an approach based on current feedback-controlled tip positioning to maintain long-term single-channel recordings for up to 3 h. We develop a hybrid positioning control system, where the channel current is used as feedback to control the vertical movement of the silver tip and, subsequently, control the number of protein channels inserted in the lipid membrane. Our findings reveal that the area of the lipid bilayer decreases with moving the silver tip up (i.e., decreasing the displacement in the z-direction). By reducing the bilayer area around the fine silver tip, we minimize the probability of multiple insertions and remove unwanted proteins. In addition, we characterize the effect of lipid properties such as fluidity on the lipid membrane area. We believe that the use of silver nanoneedles, which enables DC stable channel current, coupled with the developed tip displacement mechanism will offer more opportunities to employ these probes for chemical imaging and mapping different surfaces.
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