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Molecular discrimination inside polymer nanotubules


Recognition of small organic molecules and large biomolecules such as proteins is of great importance in pharmaceutical as well as biological applications. Recognition inside a nanoporous membrane is particularly attractive, because of the advantages associated with ligand–receptor interactions in confined spaces. Classical nanoporous membrane-based separations simply use the difference in size of the analytes relative to pore size in the membrane. In order to bring about selectivity beyond size, it is necessary that methods for functionalizing the membrane pores are readily available. Here, we describe a simple approach to functionalize the nanopores within these membranes using self-assembling and non-self-assembling polymers. We show that these modified membranes separate small molecules based on size, charge and hydrophobicity. We also demonstrate here that proteins can be differentially transported through the nanopores based on their size and/or electrostatics.

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Figure 1: Schematic illustration of functionalization of the nanoporous membranes with polymers.
Figure 2: Molecular structures of the compounds used in this study.
Figure 3: Electron microscopy and pore size measurements of the polymer nanotubes and photograph of the separation of dye molecules.
Figure 4: Separation of dyes and proteins using the polymer-modified membranes.


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This work was partially supported by the National Science Foundation Center for Fueling the Future (CHE-0739227) and Nanoscale Science and Engineering Center (DMI-0531171) at the University of Massachusetts Amherst. We thank J. Zimberlin for help with the pressure change measurements during the determination of pore size.

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E.N.S. and K.K. performed the experiments. All authors analysed the data, carried out project planning, discussed the results and commented on the manusript.

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Correspondence to S. Thayumanavan.

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Savariar, E., Krishnamoorthy, K. & Thayumanavan, S. Molecular discrimination inside polymer nanotubules. Nature Nanotech 3, 112–117 (2008).

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