Thursday, December 13, 2012

Molecular switch for tuning ions across nanopores by an external electric field

Xiaojing Gong, Jichen Li, Chi Guo, Ke Xu and Hui Yang



Active control of ion transport in nanoscale channels is attracting increasing attention. Recently, experimental and theoretical results have verified that depending on the charged surface of nanopores, the solution inside nanopores can contain either negative or positive ions, which does not happen in macroscale channels. However, the control of the surface chemistry of synthetic nanopores is difficult and the design of nanotubes with novel recognition mechanisms that regulate the ionic selectivity of negative and positive charges remains a challenge. We present here a design for an ion-selective nanopore that is controllable by external charges. Our molecular dynamics simulations show that this remarkable selectivity can be switched from predominantly negative to positive ions and that the magnitude of the ionic flux can be varied by changing the distance of the external charges. The results suggest that the hydration structures around ions play a prominent role in the selecti...



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