Surface modification of single track-etched nanopores with surfactant CTAB.

In this letter, we report a method to modify the surface charge property of single track-etched nanopores with a cationic surfactant (CTAB). The dependence of surface charge density on the surfactant concentration was investigated by measuring the streaming current when the nanopore was immersed in 0.01 M KCl solution with different CTAB concentrations. The results showed that, when the concentration of CTAB was increased gradually, the surface charge of the nanopore was inverted from negative to positive. Our calculation indicated that the surface charge density changed from -9 to 8 mC/m2. We utilized this method to modify the surface property of single conical track-etched nanopores. Its current rectification properties (both the direction and magnitude) were successfully tuned by adjusting the CTAB concentration in the solutions.