A self-assembly pathway to aligned monodomain gels

Journal name:
Nature Materials
Volume:
9,
Pages:
594–601
Year published:
DOI:
doi:10.1038/nmat2778
Received
Accepted
Published online

Abstract

Aggregates of charged amphiphilic molecules have been found to access a structure at elevated temperature that templates alignment of supramolecular fibrils over macroscopic scales. The thermal pathway leads to a lamellar plaque structure with fibrous texture that breaks on cooling into large arrays of aligned nanoscale fibres and forms a strongly birefringent liquid. By manually dragging this liquid crystal from a pipette onto salty media, it is possible to extend this alignment over centimetres in noodle-shaped viscoelastic strings. Using this approach, the solution of supramolecular filaments can be mixed with cells at physiological temperatures to form monodomain gels of aligned cells and filaments. The nature of the self-assembly process and its biocompatibility would allow formation of cellular wires in situ that have any length and customized peptide compositions for use in biological applications.

At a glance

Figures

  1. Strings and gels with long-range internal alignment.
    Figure 1: Strings and gels with long-range internal alignment.

    a,b, A peptide amphiphile solution coloured with trypan blue injected into phosphate-buffered saline after heat treatment. c, The same solution dragged through a thin layer of aqueous CaCl2 to form a noodle-like string. d, A knot made with peptide amphiphile string. e, Birefringence of a bubble gel observed between cross polars suggesting the presence of macroscopically aligned domains. f, Similar domains in a gel film. g, Peptide amphiphile noodle spirals prepared on a spin coater. h, Birefringence of a single string suggesting alignment along the string axis. i, Light extinction between cross polars at the crosspoint of two noodles demonstrating uniform alignment in each.

  2. SEM evidence of massive alignment versus isotropy of nanofibre bundles.
    Figure 2: SEM evidence of massive alignment versus isotropy of nanofibre bundles.

    a,c, Aligned nanofibre bundles in macroscopic strings formed by dragging thermally treated amphiphile solutions onto a CaCl2 solution. b,d, Isotropic network of nanofibre bundles formed by adding CaCl2 to unheated amphiphile solutions. e,f, SAXS of hydrogel strings prepared using peptide amphiphile solutions with and without heat treatment.

  3. Morphological changes resulting from thermal treatment.
    Figure 3: Morphological changes resulting from thermal treatment.

    a, TEM obtained after a QFDE preparation of peptide amphiphile solution at 80 °C revealing a micrometre-sized, sheet-like plaque structure. b, Higher-resolution QFDE-TEM of the sheet-like structures revealing a surface pattern with a periodicity of about 7.5 nm. c, SAXS of peptide amphiphile solutions treated at different thermal conditions. d, QFDE-TEM of aligned nanofibre bundles templated by the sheet-like plaque after the peptide amphiphile solution was cooled to room temperature. e, SEM of plaques that were captured by adding CaCl2 at 80 °C. f, SEM of a plaque breaking into nanofibre bundles. g,h, Schematic representation of a plaque at high temperature (g) and its rupture into fused bundles on cooling (h). i,j, Schematic representation of the cross-section of a plaque formed by fused fibres (i) and of a fibre bundle (j).

  4. Cell alignment in strings of aligned filaments.
    Figure 4: Cell alignment in strings of aligned filaments.

    a, Preferential alignment of encapsulated hMSCs along the string axis. b, Calcein-labelled aligned cells cultured in string. c, SEM images at different magnifications of a single cell in a string (inset is the zoom-out view; the arrow indicates the alignment direction). d, A conductive black string formed by dispersing carbon nanotubes in peptide amphiphile solutions before heating. The SEM micrograph on the right shows aligned nanofibre bundles in the black string. e, Top: calcium fluorescence image of HL-1 cardiomyocytes encapsulated in a noodle-like string. Below: successive spatial maps of calcium fluorescence intensity travelling at 80-ms intervals, showing the propagation of an electrical signal throughout the entire string and demonstrating a functional cardiac syncytium. f, Calcium fluorescence intensity signal in time at three points in the string marked by colour in e, showing repeated propagating action potentials.

References

  1. Whitesides, G. M., Mathias, J. P. & Seto, C. T. Molecular self-assembly and nanochemistry—a chemical strategy for the synthesis of nanostructures. Science 254, 13121319 (1991).
  2. Reches, M. & Gazit, E. Casting metal nanowires within discrete self-assembled peptide nanotubes. Science 300, 625627 (2003).
  3. Kim, S. O. et al. Epitaxial self-assembly of block copolymers on lithographically defined nanopatterned substrates. Nature 424, 411414 (2003).
  4. Nelson, R. et al. Structure of the cross-beta spine of amyloid-like fibrils. Nature 435, 773778 (2005).
  5. Dobson, C. M. Protein folding and misfolding. Nature 426, 884890 (2003).
  6. Chung, C. Y., Bien, H. & Entcheva, E. The role of cardiac tissue alignment in modulating electrical function. J. Cardiovasc. Electr. 18, 13231329 (2007).
  7. Davies, S. J. A., Goucher, D. R., Doller, C. & Silver, J. Robust regeneration of adult sensory axons in degenerating white matter of the adult rat spinal cord. J. Neurosci. 19, 58105822 (1999).
  8. Feinberg, A. W. et al. Muscular thin films for building actuators and powering devices. Science 317, 13661370 (2007).
  9. Merzlyak, A., Indrakanti, S. & Lee, S. W. Genetically engineered nanofiber-like viruses for tissue regenerating materials. Nano Lett. 9, 846852 (2009).
  10. Bettinger, C. J., Langer, R. & Borenstein, J. T. Engineering substrate topography at the micro- and nanoscale to control cell function. Angew. Chem. Int. Ed. 48, 54065415 (2009).
  11. Kato, T., Mizoshita, N. & Kishimoto, K. Functional liquid-crystalline assemblies: Self-organized soft materials. Angew. Chem. Int. Ed. 45, 3868 (2006).
  12. Gin, D. L., Gu, W. Q., Pindzola, B. A. & Zhou, W. J. Polymerized lyotropic liquid crystal assemblies for materials applications. Acc. Chem. Res. 34, 973980 (2001).
  13. Stupp, S. I. & Osenar, P. in Polymerization in Organized Media in Synthesis of Polymers (ed. Schlüter, A. D.) (Wiley-VCH, 1999).
  14. Greiner, A. & Wendorff, J. H. A fascinating method for the preparation of ultrathin fibres. Angew. Chem. Int. Ed. 46, 56705703 (2007).
  15. Hartgerink, J. D., Beniash, E. & Stupp, S. I. Self-assembly and mineralization of peptide-amphiphile nanofibers. Science 294, 16841688 (2001).
  16. Behanna, H. A., Donners, J. J. J. M., Gordon, A. C. & Stupp, S. I. Coassembly of amphiphiles with opposite peptide polarities into nanofibers. J. Am. Chem. Soc. 127, 11931200 (2005).
  17. Ruberti, J. W. et al. Quick-freeze/deep-etch visualization of age-related lipid accumulation in Bruch’s membrane. Invest. Ophthalmol. Vis. Sci. 44, 17531759 (2003).
  18. Bull, S. R. et al. Magnetic resonance imaging of self-assembled biomaterial scaffolds. Bioconjugate Chem. 16, 13431348 (2005).
  19. Glatter, O. & Kratky, O. (eds) Small Angle X-ray Scattering (Academic, 1982).
  20. Tovar, J. D., Claussen, R. C. & Stupp, S. I. Probing the interior of peptide amphiphile supramolecular aggregates. J. Am. Chem. Soc. 127, 73377345 (2005).
  21. Cheng, H., Zhang, K., Libera, J. A., de la Cruz, M. O. & Bedzyk, M. J. Polynucleotide adsorption to negatively charged surfaces in divalent salt solutions. Biophys. J. 90, 11641174 (2006).
  22. Jiang, H. Z., Guler, M. O. & Stupp, S. I. The internal structure of self-assembled peptide amphiphiles nanofibers. Soft. Matter. 3, 454462 (2007).
  23. Lenz, P. & Nelson, D. R. Hexatic undulations in curved geometries. Phys. Rev. E 67, 031502 (2003).
  24. Sandre, O., Moreaux, L. & Brochard-Wyart, F. Dynamics of transient pores in stretched vesicles. Proc. Natl Acad. Sci. USA 96, 1059110596 (1999).
  25. De Wit, A., Gallez, D. & Christov, C. I. Nonlinear evolution equations for thin liquid films with insoluble surfactants. Phys. Fluids 6, 32563266 (1994).
  26. Oron, A., Davis, S. H. & Bankoff, S. G. Long-scale evolution of thin liquid films. Rev. Mod. Phys. 69, 931980 (1997).
  27. Liu, Y. S., Li, M. H., Bansil, R. & Steinhart, M. Kinetics of phase transition from lamellar to hexagonally packed cylinders for a triblock copolymer in a selective solvent. Macromolecules 40, 94829490 (2007).
  28. Solis, F. J., Funkhouser, C. M. & Thornton, K. Conditions for overall planarity in membranes: Applications to multicomponent membranes with lamellar morphology. Europhys. Lett. 82, 38001 (2008).
  29. Mayes, A. M. & de la Cruz, M. O. Strain effects on the thermal stability of rod eutectics. Acta Metall. 37, 615620 (1989).
  30. Ide, Y. & Ophir, Z. Orientation development in thermotropic liquid crystal polymers. Polym. Eng. Sci. 23, 261265 (1983).
  31. Larson, R. G. & Mead, D. W. The Ericksen Number and Deborah Number cascades in sheared polymeric nematics. Liq. Cryst. 15, 151169 (1993).
  32. Reneker, D. H., Yarin, A. L., Fong, H. & Koombhongse, S. Bending instability of electrically charged liquid jets of polymer solutions in electrospinning. J. Appl. Phys. 87, 45314547 (2000).
  33. Barham, P. J. & Keller, A. High-strength polyethylene fibres from solution and gel spinning. J. Mater. Sci. 20, 22812302 (1985).
  34. Fujikake, H., Murashige, T., Sato, H., Kawakita, M. & Kikuchi, H. Molecular alignment enhancement phenomenon of polymer formed from a liquid crystal monomer in a liquid crystal solvent. Appl. Phys. Lett. 82, 16221624 (2003).
  35. Tranquillo, R. T. Self-organization of tissue-equivalents: the nature and role of contact guidance. Biochem. Soc. Symp. 65, 2742 (1999).
  36. Claycomb, W. C. et al. A cardiac muscle cell line that contracts and retains phenotypic characteristics of the adult cardiomyocyte. Proc. Natl Acad. Sci. USA 95, 29792984 (1998).

Download references

Author information

  1. These authors contributed equally to this work

    • Shuming Zhang &
    • Megan A. Greenfield

Affiliations

  1. Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA

    • Shuming Zhang,
    • Jason R. Mantei,
    • Monica Olvera de la Cruz &
    • Samuel I. Stupp
  2. Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA

    • Megan A. Greenfield &
    • Monica Olvera de la Cruz
  3. Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, Illinois 60611, USA

    • Alvaro Mata,
    • Ronit Bitton,
    • Conrado Aparicio,
    • Monica Olvera de la Cruz &
    • Samuel I. Stupp
  4. Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA

    • Liam C. Palmer,
    • Monica Olvera de la Cruz &
    • Samuel I. Stupp
  5. Department of Medicine, Northwestern University, Chicago, Illinois 60611, USA

    • Samuel I. Stupp
  6. Present address: Nanotechnology Platform, Parc Cientific, 08028 Barcelona, Spain

    • Alvaro Mata

Contributions

S.Z., M.A.G., A.M., L.C.P., R.B., C.A. and J.R.M. carried out experiments. M.A.G. and M.O.d.l.C. generated numerical data. M.A.G., M.O.d.l.C. and S.I.S developed a theoretical model. S.Z., M.A.G., L.C.P., R.B., J.R.M., M.O.d.l.C. and S.I.S. wrote the paper.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Supplementary information

PDF files

  1. Supplementary Information (2.23 MB)

    Supplementary Information

Movies

  1. Supplementary Information (8.50 MB)

    Supplementary Information

Additional data