Mechanistic Study of the Conductance and Enhanced Single-Molecule Detection in a Polymer-Electrolyte Nanopore.
Mechanistic Study of the Conductance and Enhanced Single-Molecule Detection in a Polymer-Electrolyte Nanopore.
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DOI：
10.1021/acsnanoscienceau.2c00050
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发表时间：
2023-04-19
期刊：
影响因子：
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通讯作者：
Edwards, Martin Andrew
中科院分区：
文献类型：
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作者：
Marcuccio, Fabio;Soulias, Dimitrios;Chau, Chalmers C C;Radford, Sheena E;Hewitt, Eric;Actis, Paolo;Edwards, Martin Andrew
固态纳米孔已被广泛用于生物分子的检测，但低信噪比仍然代表了区分基本上小于纳米孔直径的核酸和蛋白质序列的主要障碍。将50%的聚（乙）二醇（PEG）添加到外部溶液中是增强此类生物分子检测的简单方法。在这里，我们用有限元建模和实验证明，将PEG添加到外部溶液中会在阳离子和阴离子的传输特性中引入强烈的不平衡，从而极大地影响纳米孔的电流响应。我们进一步表明，强不对称电流响应是由于在纳米移液管尖端区域的极性依赖性离子分布和运输，导致离子耗尽或富集几十纳米的孔径。我们提供的证据表明，在纳米孔外的浴中的阳离子/阴离子的扩散系数的降低/增加的组合以及易位分子与纳米孔-浴界面之间的相互作用是易位信号增加的原因。我们希望这种新的机制有助于进一步发展纳米孔传感表明，调整离子的扩散系数可以提高系统的灵敏度。
Solid-state nanopores have been widely employed in the detection of biomolecules, but low signal-to-noise ratios still represent a major obstacle in the discrimination of nucleic acid and protein sequences substantially smaller than the nanopore diameter. The addition of 50% poly(ethylene) glycol (PEG) to the external solution is a simple way to enhance the detection of such biomolecules. Here, we demonstrate with finite-element modeling and experiments that the addition of PEG to the external solution introduces a strong imbalance in the transport properties of cations and anions, drastically affecting the current response of the nanopore. We further show that the strong asymmetric current response is due to a polarity-dependent ion distribution and transport at the nanopipette tip region, leading to either ion depletion or enrichment for few tens of nanometers across its aperture. We provide evidence that a combination of the decreased/increased diffusion coefficients of cations/anions in the bath outside the nanopore and the interaction between a translocating molecule and the nanopore–bath interface is responsible for the increase in the translocation signals. We expect this new mechanism to contribute to further developments in nanopore sensing by suggesting that tuning the diffusion coefficients of ions could enhance the sensitivity of the system.