The internal structure of self-assembled peptide amphiphiles nanofibers

Jiang, Hongzhou; Güler, Mustafa O.; Stupp, Samuel I.

doi:10.1039/b614426h

Cited by 125 publications

(166 citation statements)

References 55 publications

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“…1-3, available at www.jneurosci.org as supplemental material). The cylinders have a well defined diameter in the range of 6 -8 nm and consist of ␤-sheet assemblies that tend to be parallel to the nanofibers (Jiang et al, 2007). Because each molecule contains an epitope sequence at its hydrophilic terminus, the nanostructures assembled in an aqueous medium are able to display bioactive sequences perpendicular to their long axis at nearly van der Waals density.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembling Nanofibers Inhibit Glial Scar Formation and Promote Axon Elongation after Spinal Cord Injury

Tysseling¹,

Sahni²,

Niece³

et al. 2008

J. Neurosci.

636

524

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Peptide amphiphile (PA) molecules that self-assemble in vivo into supramolecular nanofibers were used as a therapy in a mouse model of spinal cord injury (SCI). Because self-assembly of these molecules is triggered by the ionic strength of the in vivo environment, nanoscale structures can be created within the extracellular spaces of the spinal cord by simply injecting a liquid. The molecules are designed to form cylindrical nanofibers that display to cells in the spinal cord the laminin epitope IKVAV at nearly van der Waals density. IKVAV PA nanofibers are known to inhibit glial differentiation of cultured neural stem cells and to promote neurite outgrowth from cultured neurons. In this work, in vivo treatment with the PA after SCI reduced astrogliosis, reduced cell death, and increased the number of oligodendroglia at the site of injury. Furthermore, the nanofibers promoted regeneration of both descending motor fibers and ascending sensory fibers through the lesion site. Treatment with the PA also resulted in significant behavioral improvement. These observations demonstrate that it is possible to inhibit glial scar formation and to facilitate regeneration after SCI using bioactive three-dimensional nanostructures displaying high densities of neuroactive epitopes on their surfaces.

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Section: Introductionmentioning

confidence: 99%

Self-Assembling Nanofibers Inhibit Glial Scar Formation and Promote Axon Elongation after Spinal Cord Injury

Tysseling¹,

Sahni²,

Niece³

et al. 2008

J. Neurosci.

636

524

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“…Self-assembly of PA molecules is further controlled by hydrophobicity of the alkyl tail and hydrogen bonding between adjacent peptides. The morphology of the PA assemblies has been characterized by transmission and scanning electron microscopy techniques (TEM and SEM), atomic force microscopy (AFM), circular dichroism (CD), nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy (Behanna et al 2005;Jiang et al 2007).…”

Section: One-dimensional Assembliesmentioning

confidence: 99%

Supramolecular self-assembly codes for functional structures

Palmer

Velichko

Cruz

et al. 2007

Phil. Trans. R. Soc. A.

102

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Small-molecule self-assembly has proven to be a rich field for the controlled synthesis of supramolecular objects with the size scale of polymers and interesting properties. Using several recent examples from our laboratory, we discuss the development of chemical structure codes for supramolecular self-assembly objects with defined shapes. The resulting materials formed by these objects are promising for electronic functions and biological functions for regenerative medicine.

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“…The structural characterization of these supramolecular fibers consisting of β-sheets and hydrophobic collapse is not trivial since they are not crystals but do contain internal order. 29 The mechanical integrity of the PA gels that are formed is also limited due to the absence of any internal covalent bonds connecting the PA monomers. In our original work, we showed that cysteine residues could be used to internally crosslink the nanofibers.…”

Section: Introductionmentioning

confidence: 99%

“…30 More recently, our group has also determined that there is order in the inner hydrophobic core of the nanofibers containing alkyl chains. 29 In the present work, we have placed the diacetylene groups in the hydrophobic alkyl segments and studied the polymerization both as a probe for the nanofiber's internal structure as well as a strategy to obtain novel properties.…”

Section: Introductionmentioning

confidence: 99%

Peptide Amphiphile Nanofibers with Conjugated Polydiacetylene Backbones in Their Core

2008

Self Cite

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The coupling of electronic and biological functionality through self-assembly is an interesting target in supramolecular chemistry. We report here on a set of diacetylene-derivatized peptide amphiphiles (PAs) that react to form conjugated polydiacetylene backbones following self-assembly into cylindrical nanofibers. The polymerization reaction yields highly conjugated backbones when the peptidic segment of the PAs has a linear, as opposed to a branched, architecture. Given the topotactic nature of the polymerization, these results suggest that a high degree of internal order exists in the supramolecular nanofibers formed by the linear PA. On the basis of microscopy, the formation of a polydiacetylene backbone to covalently connect the β-sheets that help form the fibers does not disrupt the fiber shape. Interestingly, we observe the appearance of a polydiacetylene (PDA) circular dichroism band at 547 nm in linear PA nanofibers suggesting the conjugated backbone in the core of the nanostructures is twisted. We believe this CD signal is due to chiral induction by the β-sheets, which are normally twisted in helical fashion. Heating and cooling shows simultaneous changes in β-sheet and conjugated backbone structure, indicating they are both correlated. At the same time, poor polymerization in nanofibers formed by branched PAs indicates that less internal order exists in these nanostructures and, as expected, then a circular dichroism signal is not observed for the conjugated backbone. The general variety of materials investigated here has the obvious potential to couple electronic properties and in vitro bioactivity. Furthermore, the polymerization of monomers in peptide amphiphile assemblies by a rigid conjugated backbone also leads to mechanical robustness and insolubility, two properties that may be important for the patterning of these materials at the cellular scale.

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The internal structure of self-assembled peptide amphiphiles nanofibers

Cited by 125 publications

References 55 publications

Self-Assembling Nanofibers Inhibit Glial Scar Formation and Promote Axon Elongation after Spinal Cord Injury

Self-Assembling Nanofibers Inhibit Glial Scar Formation and Promote Axon Elongation after Spinal Cord Injury

Supramolecular self-assembly codes for functional structures

Peptide Amphiphile Nanofibers with Conjugated Polydiacetylene Backbones in Their Core

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