Ion-specific anomalous electrokinetic effects in hydrophobic nanochannels.
We show with computer simulations that anomalous electrokinetic effects, such as ion specificity and nonzero zeta potentials for uncharged surfaces, are generic features of electro-osmotic flow in hydrophobic channels. This behavior is due to the stronger attraction of larger ions to the "vapor-liquidlike" interface induced by a hydrophobic surface. We propose an analytical model involving a modified Poisson-Boltzmann description for the ion density distributions that quantitatively predicts the anomalous flow profiles. This description includes as a crucial component an ion-size-dependent hydrophobic solvation energy. These results provide an effective framework for predicting ion-specific effects, with potentially important implications for biological modeling.
Huang
David M
DM
Université de Lyon, Université Lyon 1, LPMCN, and CNRS, UMR 5586, F-69622 Villeurbanne Cedex, France.
Cottin-Bizonne
Cécile
C
Ybert
Christophe
C
Bocquet
Lydéric
L
D003198:Computer Simulation; D004553:Electric Conductivity; D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions / Q000737:chemistry*; D008954:Models, Biological; D049329:Nanostructures / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012974:Sodium Iodide / Q000737:chemistry
D007477:Ions; D012965:Sodium Chloride; D012974:Sodium Iodide