title: Self-assembly of crystalline nanotubes from monodisperse amphiphilic diblock copolypeptoid tiles.
abstract: The folding and assembly of sequence-defined polymers into precisely ordered nanostructures promises a class of well-defined biomimetic architectures with specific function. Amphiphilic diblock copolymers are known to self-assemble in water to form a variety of nanostructured morphologies including spheres, disks, cylinders, and vesicles. In all of these cases, the predominant driving force for assembly is the formation of a hydrophobic core that excludes water, whereas the hydrophilic blocks are solvated and extend into the aqueous phase. However, such polymer systems typically have broad molar mass distributions and lack the purity and sequence-defined structure often associated with biologically derived polymers. Here, we demonstrate that purified, monodisperse amphiphilic diblock copolypeptoids, with chemically distinct domains that are congruent in size and shape, can behave like molecular tile units that spontaneously assemble into hollow, crystalline nanotubes in water. The nanotubes consist of stacked, porous crystalline rings, and are held together primarily by side-chain van der Waals interactions. The peptoid nanotubes form without a central hydrophobic core, chirality, a hydrogen bond network, and electrostatic or π-π interactions. These results demonstrate the remarkable structure-directing influence of n-alkane and ethyleneoxy side chains in polymer self-assembly. More broadly, this work suggests that flexible, low-molecular-weight sequence-defined polymers can serve as molecular tile units that can assemble into precision supramolecular architectures.
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, University of Oslo, 0315 Oslo, Norway;
authors.forename: Reidar
authors.initials: R
authors.lastname: Lund
authors.affiliation: Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Downing
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720.
authors.forename: Nitash P
authors.initials: NP
authors.lastname: Balsara
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; rnzuckermann@lbl.gov.
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Zuckermann
mesh_terms: D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D043942:Nanotubes / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D010455:Peptides; D011108:Polymers; D013501:Surface-Active Agents; D014867:Water
keywords: peptoid nanostructures; peptoid polymers; polymer amphiphiles; sequence-defined polymers; supramolecular assembly