Rectification of the Ionic Current through Carbon Nanotubes by Electrostatic Assembly of Polyelectrolytes

Rectification of the ionic current flowing through nanotubes embedded in a polymeric membrane is achieved by selective adsorption of polycations to the nanotubes' mouths. A one-dimensional model of ionic flux through a nanotube with charged entrance regions qualitatively describes current-voltage curves before and after polycation exposure; reversal potential measurements confirm that charge reversal takes place upon polycation adsorption. The inherent simply of this electrostatic approach makes it attractive in membrane and nanofluidic applications employing rectification.