Single conical nanopores displaying pH-tunable rectifying characteristics. manipulating ionic transport with zwitterionic polymer brushes.

In this work we describe for the first time the integration of "smart" polymer brushes into single conical nanopores to obtain a new highly functional signal-responsive chemical nanodevice. The responsive brushes were constituted of zwitterionic monomers whose charge is regulated via pH changes in the environmental conditions. The pH-dependent chemical equilibrium of the monomer units provides a fine-tuning of the ionic transport though the nanopore by simply presetting the pH of the electrolyte solution. Our results demonstrate that this strategy enables a higher degree of control over the rectification properties when compared to the nanochannels modified with charged monolayer assemblies. We envision that these results will create completely new avenues to build-up "smart" nanodevices using responsive polymer brushes integrated into single conical nanopores.

[1]  C. R. Martin,et al.  Developing synthetic conical nanopores for biosensing applications. , 2007, Molecular bioSystems.

[2]  S. Minko.  Responsive polymer materials : design and applications , 2006 .

[3]  Zuzanna S Siwy,et al.  Learning Nature's Way: Biosensing with Synthetic Nanopores , 2007, Science.

[4]  M. Bruening,et al.  Surface-Initiated Thermal Radical Polymerization on Gold , 2001 .

[5]  L. A. Baker,et al.  Nanopores: a makeover for membranes. , 2008, Nature nanotechnology.

[6]  R. Spohr.  Status of ion track technology—Prospects of single tracks , 2005 .

[7]  Wilhelm T. S. Huck,et al.  Tunable Wettability by Clicking Counterions Into Polyelectrolyte Brushes , 2007 .

[8]  K. Healy,et al.  Modifying the surface charge of single track-etched conical nanopores in polyimide , 2008, Nanotechnology.

[9]  Meni Wanunu,et al.  Chemically modified solid-state nanopores. , 2007, Nano letters.

[10]  Arun Majumdar,et al.  Ion transport in nanofluidic channels , 2004 .

[11]  P Hänggi,et al.  Rectification in synthetic conical nanopores: a one-dimensional Poisson-Nernst-Planck model. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  Z. Siwy,et al.  Nanofluidic Bipolar Transistors , 2008 .

[13]  Z. Siwy,et al.  Conical-nanotube ion-current rectifiers: the role of surface charge. , 2004, Journal of the American Chemical Society.

[14]  C. Martin,et al.  pH-switchable, ion-permselective gold nanotubule membrane based on chemisorbed cysteine. , 2001, Analytical chemistry.

[15]  Q. Ouyang,et al.  Asymmetric properties of ion transport in a charged conical nanopore. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[16]  Muhammad Raza Shah,et al.  Synthetic ion channels and pores (2004-2005). , 2006, Chemical Society reviews.

[17]  Z. Siwy,et al.  Ion‐Current Rectification in Nanopores and Nanotubes with Broken Symmetry , 2006 .

[18]  A. Alcaraz,et al.  Theoretical description of the ion transport across nanopores with titratable fixed charges , 2006, Cell Biochemistry and Biophysics.

[19]  William J. Brittain,et al.  Polymer brushes : synthesis, characterization, applications , 2004 .

[20]  A. Majumdar,et al.  Electrostatic control of ions and molecules in nanofluidic transistors. , 2005, Nano letters.

[21]  Reimar Spohr,et al.  Diode-like single-ion track membrane prepared by electro-stopping , 2001 .

[22]  Wilhelm T S Huck,et al.  UCST wetting transitions of polyzwitterionic brushes driven by self-association. , 2006, Angewandte Chemie.

[23]  J. Rühe,et al.  Polymer Layers Through Self-Assembled Monolayers of Initiators , 1998 .

[24]  Stephen W. Feldberg,et al.  Current Rectification at Quartz Nanopipet Electrodes , 1997 .

[25]  Javier Cervera,et al.  Ionic conduction, rectification, and selectivity in single conical nanopores. , 2006, The Journal of chemical physics.