Effect of Surface Charge on the Resistive Pulse Waveshape during Particle Translocation through Glass Nanopores
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- 作者：Wen-Jie Lan ; Clemens Kubeil ; Jie-Wen Xiong ; Andreas Bund ; Henry S. White
- 刊名：Journal of Physical Chemistry C
- 出版年：2014
- 出版时间：February 6, 2014
- 年：2014
- 卷：118
- 期：5
- 页码：2726-2734
- 全文大小：472K
- ISSN：1932-7455
文摘
This paper describes a fundamental study of the effect of electrostatic interactions on the resistive pulse waveshape associated with translocation of charged nanoparticles through a conical-shaped, charged glass nanopore. In contrast to single-peak resistive pulses normally associated with resistive-pulse methods, biphasic pulses, in which the normal current decrease is preceded by a current increase, were observed in the current鈥搕ime recordings when a high negative potential (lower than 鈭?.4 V) is applied between the pore interior and the external solution. The biphasic pulse is a consequence of the offsetting effects of an increased ion conductivity induced by the surface charge of the translocating particle and the current decrease due to the volume exclusion of electrolyte solution by the particle. Finite-element simulations based on the coupled Poisson鈥揘ernst鈥揚lanck equations and a particle trajectory calculation successfully capture the evolution of the waveshape from a single resistive pulse to a biphasic response as the applied voltage is varied. The simulation results demonstrate that the surface charges of the nanopore and the particle are responsible for the voltage-dependent shape evolution. Additionally, the use of high ionic strength solution or high pressures to drive particle translocation was found to eliminate the biphasic response. The former is due to the screening of the electrical double layer, while the latter results from the solution flow preventing formation of an equilibrium double layer ion distribution within the nanopore, similar to the previously reported elimination of ion current rectification when solution flows through a nanopore.