Mechanism of KCl Enhancement in Detection of Nonionic Polymers by Nanopore Sensors

被引：63
作者：
Rodrigues, Claudio G. [1 ]
Machado, Dijanah C. [1 ]
Chevtchenko, Sergio F. [1 ]
Krasilnikov, Oleg V. [1 ]
机构：
[1] Univ Fed Pernambuco, Dept Biophys & Radiobiol, BR-50670901 Recife, PE, Brazil
来源：
BIOPHYSICAL JOURNAL | 2008年 / 95卷 / 11期
关键词：
D O I：
10.1529/biophysj.108.140814
中图分类号：
Q6 [生物物理学];
学科分类号：
071011 ;
摘要：
The mechanisms of KCl-induced enhancement in identification of individual molecules of poly(ethylene glycol) using solitary alpha-hemolysin nanoscale pores are described. The interaction of single molecules with the nanopore causes changes in the ionic current flowing through the pore. We show that the on-rate constant of the process is several hundred times larger and that the off-rate is several hundred times smaller in 4 M KCl than in 1 M KCl. These shifts dramatically improve detection and make single molecule identification feasible. KCl also changes the solubility of poly(ethylene glycol) by the same order of magnitude as it changes the rate constants. In addition, the polymer-nanopore interaction is determined to be a strong non-monotonic function of voltage, indicating that the flexible, nonionic poly(ethylene glycol) acts as a charged molecule. Therefore, salting-out and Coulombic interactions are responsible for the KCl-induced enhancement. These results will advance the development of devices with sensor elements based on single nanopores.
引用
收藏
页码：5186 / 5192
页数：7
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