TY - JOUR
T1 - Mechanism of KCl enhancement in detection of nonionic polymers by nanopore sensors
AU - Rodrigues, Claudio G.
AU - Machado, Dijanah C.
AU - Chevtchenko, Sérgio F.
AU - Krasilnikov, Oleg V.
PY - 2008/12/1
Y1 - 2008/12/1
N2 - The mechanisms of KCl-induced enhancement in identification of individual molecules of poly(ethylene glycol) using solitary α-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.
AB - The mechanisms of KCl-induced enhancement in identification of individual molecules of poly(ethylene glycol) using solitary α-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.
UR - http://www.scopus.com/inward/record.url?scp=58149360789&partnerID=8YFLogxK
U2 - 10.1529/biophysj.108.140814
DO - 10.1529/biophysj.108.140814
M3 - Article
C2 - 18805926
AN - SCOPUS:58149360789
SN - 0006-3495
VL - 95
SP - 5186
EP - 5192
JO - Biophysical Journal
JF - Biophysical Journal
IS - 11
ER -