The discovery of self-assembling peptides, has opened a realm of opportunity for designing short peptide sequences which have applications in regenerative medicine for tissue repair, scaffolding for tissue engineering, drug delivery and sutures. The properties of such peptides, namely; their complex and complementary structures, biocompatibility, chemical versatility and biological recognition abilities have lead them to their versatility. In this study, aromatic oligopeptide sequences were examined for their ability to form structures such as nanofibers, nanospheres as well as cationic, amphiphilic peptides which self-assemble into micelles and their applications as targeted drug carriers. Non-covalent interactions such as π-stacking, hydrogen bonding, and hydrophobic interactions promote peptide self-assembly and the resultant architectures can vary as nanofibers, nanospheres or nanotubes; based on the composition of the short peptide strands and the dominant non-covalent forces.
In this study, the influence of electrostatic forces on the assembly of biodegradable nanofibers and nanospheres was studied. Mass spectroscopy to understand the changes in the chemical composition, infrared spectroscopy (FT-IR) and circular dichroism (CD) spectroscopy to study the secondary structure along with differential scanning calorimetry (DSC) to investigate the thermal behavior of the obtained fibers and spheres were performed. Other amphiphilic peptide sequences were designed for the formation of micelles for applications as drug carriers. Polar flavonoids/polyphenols, including quercetin and pro-anthocyanidins, and non-polar triterpenoids including ursolic acid and derivatives are the two main categories of cranberry fruits natural compounds which were studied. Self-assembled micelles or other peptide-based carriers deposited via electrospraying techniques represent a possible route to target delivery of the flavonoids to tissues and organs of interest. Response to the external stimuli such as pH, temperature and presence of enzymes are some of the advantages that these nanostructures provide for drug delivery systems. We have begun to explore the fabrication of these structures, ability of drug loading and their mechanisms of drug release and their biodistribution both in vitro and in vivo. We will assess the suitability of these natural compounds for micellar delivery, the extent of delivery to cells, and whether tumor cell proliferation is reduced as a result.