Affinity of glycopeptide nanofibers to growth factors and their effects on cells
The development of scaffolds for growth factor delivery is a promising approach for tissue regeneration applications due to their crucial roles during regeneration. Growth factor secretion and interactions with glycosaminoglycans are essential steps for the regulation of cellular behavior. Therefore, glycosaminoglycan-mimetic scaffolds provide a great opportunity to modulate the effects of growth factor actions on cell fate. In this thesis, sugar-bearing peptide amphiphile molecules were characterized and tested for VEGF, FGF-2 and NGF affinity. ELISA-based affinity analyses revealed that glycopeptide nanofibers had high affinity to NGF; however, glycopeptides alone were not enough to interact efficiently with VEGF and FGF-2. Since VEGF and NGF contain heparin-binding domains, the addition of a sulfonated peptide amphiphile increased the affinity of the nanofiber network to these growth factors. Glycopeptide-sulfonate nanofibers were also found to promote in vitro tube formation through their VEGF and FGF-2 affinity. VEGF release profiles of HUVECs indicated that increasing concentration of VEGF may provide autocrine signaling and enhance tube formation without any exogenous pro-angiogenic factor addition. In addition, when NGF-responsive PC-12 cells were cultured on glycopeptide nanofibers, they extended their neurites to an extent comparable with a widely-used positive control molecule (poly-L-lysine). These results suggest that glycosaminoglycan-mimetic glycopeptide nanofiber networks can be used as efficient growth factor presentation platforms for tissue regeneration applications to induce angiogenesis or peripheral nerve regeneration.