Maintaining Single-Channel Recordings on a Silver Nanoneedle through Probe Design and Feedback Tip Positioning Control
Maintaining Single-Channel Recordings on a Silver Nanoneedle through Probe Design and Feedback Tip Positioning Control
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DOI：
10.1021/acs.jpcb.2c06275
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发表时间：
2022-11-17
影响因子：
3.3
通讯作者：
White，Ryan J.
中科院分区：
文献类型：
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作者：
Hussein，Essraa A.;White，Ryan J.
离子通道蛋白具有原子级的孔径精度和高信噪比，在纳米孔传感和分子通量成像领域显示出巨大的应用前景。更具体地说，离子通道探针，其中蛋白质通道整合在固体探针的末端，可以实现高度局部化的检测。与更传统的玻璃微吸管离子通道探针相比，金和银等金属探针材料已经开发出来，以支持脂质双层并允许使用更小的探针或纳米针。由于在制造过程中针尖周围形成了AgCl层，因此银探针会支持持续的直流稳定沟道电流，因此是更好的选择。然而，目前离子通道测量中的一个挑战是保持单通道记录。多个蛋白质的插入使数据分析复杂化，并破坏了双层的稳定性。在这里，我们将有希望的探针材料(Ag/AgCl)与基于电流反馈控制的针尖定位方法相结合，以保持长达3h的单通道记录。我们开发了一种混合定位控制系统，其中通道电流作为反馈来控制银尖的垂直运动，从而控制插入到脂质膜中的蛋白质通道的数量。我们的发现表明，随着银尖向上移动(即减小z方向的位移)，脂质双层的面积减小。通过减少精细银尖周围的双层面积，我们将多次插入的可能性降至最低，并去除了不需要的蛋白质。此外，我们表征了脂类性质，如流动性对脂膜面积的影响。我们相信，银纳米针的使用，使直流稳定的通道电流，再加上开发的尖端位移机制，将提供更多的机会，使用这些探针进行化学成像和绘制不同的表面。
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 thez-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.