Transport at the nanoscale: temperature dependence of ion conductance |
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Authors: | Catalin Chimerel Liviu Movileanu Soroosh Pezeshki Mathias Winterhalter Ulrich Kleinekathöfer |
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Institution: | (1) School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany;(2) Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244-1130, USA |
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Abstract: | Temperature dependent ion conductance in nanopores is measured in a wide range of electrolyte concentrations and compared
with molecular modeling. Single outer membrane protein F (OmpF) channels from E. coli are reconstituted into planar lipid bilayers. In qualitative agreement with the experimental data, applied-field molecular
dynamics unraveled atomistic details of the ion transport. Comparing the temperature dependence of the channel conductance
with that of the bulk conductivity in the range from 0 to 90°C revealed that at low salt concentrations the transport is mainly
driven along the pore surface. Increasing the salt concentration saturates the surface charge transport and induces ion transport
in the center of the nanopore. The confinement of the nanopore then favors the formation of ion pairs. Stepping up the temperature
reduces the life time of the ion pairs and increases the channel conductance more than expected from the bulk behavior. |
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