title: Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation.
abstract: Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10(-2) C m(-2) needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed.
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Balme
authors.affiliation: Laboratoire de Nanomédecine, Imagerie et Thérapeutiques, EA4662, Université Franche-Comté, Centre Hospitalier Universitaire, 16 route de Gray, 25030 Besançon cedex, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Picaud
authors.affiliation: Université de Toulouse, Laboratoire de Physique Théorique (IRSAMC) UMR5152 CNRS-UPS, 118 route de Narbonne, F-31062 Toulouse, France.
authors.forename: Manoel
authors.initials: M
authors.lastname: Manghi
authors.affiliation: Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, Montpellier, F-France.
authors.forename: John
authors.initials: J
authors.lastname: Palmeri
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Mikhael
authors.initials: M
authors.lastname: Bechelany
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Cabello-Aguilar
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Adib
authors.initials: A
authors.lastname: Abou-Chaaya
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Miele
authors.affiliation: Centre de recherche sur les Ions, les Matériaux et la Photonique, UMR6252 CEA-CNRS-ENSICAEN, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 4, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Balanzat
authors.affiliation: Institut Européen des Membranes, UMR5635 ENSCM-UM-CNRS, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Janot