(395h) Peptide-DNA Hybrid Nanomaterials for Biology and Regenerative Medicine

Peptide-DNA Hybrid Nanomaterials for
Biology and Regenerative Medicine

Ronit Freeman¹, Nicholas
Stephanopoulos², Samuel I. Stupp^1,3,4.5*

(* s-stupp@northwestern.edu)

1. Simpson Querrey Institute for
BioNanotechnology, Feinberg School of Medicine, Northwestern University,
Chicago, IL 60611, United States

2. Current address: School of
Molecular Sciences, Center for Molecular Design and Biomimetics, The Biodesign
Institute Arizona State University, Tempe, AZ 85287, United States

3. Department of Materials Science
and Engineering, Northwestern University, Evanston, IL 60208, United States

4. Department of Chemistry,
Northwestern University, Evanston, IL 60208, United States

5. Department of
Medicine, Northwestern University, Chicago, IL 60611, United States

Peptides and DNA represent two
of the most attractive categories of molecules for the construction of
nanomaterials for biology and medicine. Peptides provide a rich palette of
biological functionality and self-assembly behavior, and DNA can be used to
construct complex nanostructures with programmable, dynamic properties. We
sought to merge the advantages of these two molecular platforms through the use
of peptide-DNA (P-DNA) hybrid materials. Here we will outline recent progress
in three distinct areas, each harnessing the unique potential of DNA as a novel
biomaterial.

The first system used a DNA
nanotube scaffold to present cell-adhesive peptides in a multivalent fashion (Figure
1A). Neural stem cells adhered to these DNA-peptide structures and
differentiated selectively into neurons. Both the nanostructure and the
biological signal could be independently controlled.

The second system involves the
synthesis of peptide-DNA hybrid molecules that can be linked to non-bioactive
substrates through Watson-Crick pairing to an immobilized complementary strand.
The use of these molecular modifications on cell substrates has enabled us to manipulate
different matrix functions, (Figure 1B):  (1) induce reversible biological cell
adhesion over “multiple cycles” using three orthogonal mechanisms; (2) optimize
at the nanometer scale the distance between two signals in the matrix for synergistic
signaling of the cell; and (3) probe the individual roles of two localized
signals in the matrix. This system is the first to combine all three of these
matrix functions using a single molecular platform. In particular, the platform
described demonstrates the possibility of dynamic features on cell matrices not
possible with previous approaches, which are either not reversible or use
potentially harmful stimuli to the cell such as ultraviolet light.

This system provides a
fundamentally new paradigm for DNA as a functional linker to mimic diverse ECM
properties, and the orthogonality and programmability of DNA makes this
platform highly attractive for a wide range of biological applications. In
addition, this system can be readily interfaced with other DNA
nanotechnology-based constructs, which have as of yet found only limited
application in regenerative medicine and related fields.

A third project appended DNA or
PNA(Peptide Nucleic Acids) to peptide amphiphiles (Figure 1C). These hybrid
materials merge the dynamic properties of DNA with the bioactive and
self-assembly properties of peptides. The resulting constructs were tunable and
reversible in both their physical and biological properties due to the
functionality of the DNA, allowing for dynamic signal presentation, reversible
gelation and programmable hierarchical self-assembly of peptide-based filament
structures.

The formation of 3D peptide
amphiphile gels using the nucleic acids as cross-linkers involved the formation
of long and dense bundled fibers that are enriched with nucleic acids while the
non-bundled fibers are DNA-poor. The dimensions of the fiber bundles, and as a
result, the mechanical properties of the gel network can be dynamically tuned
by the number of DNA crosslinks. This dynamic 3D microenvironment provides new
opportunities for dynamically altering different features and testing their
effect on cell behavior.