Probing Supramolecular Motion with Nuclear Magnetic Resonance in Bioactive Scaffolds that Promote Neural Regeneration in the Central Nervous System

H relaxation data, which suggest pronounced β-sheet structuring within the IKVAV domain. Furthermore, dipolar coupling measurements suggest the possible formation of salt bridges between the E and K residues, folding of PA molecules, and the potential coexistence of parallel and antiparallel molecular arrangements within the dynamic assemblies. X-ray scattering and electron microscopy also revealed a significant population of small PA clusters in equilibrium with micron-length nanofilaments in the more dynamic, bioactive systems, consistent with our previous observations on a related supramolecular system. Based on DOSY NMR, these clusters have a hydrodynamic diameter of 6.6 nm, closely matching the 6.2 nm effective diameter from solution X-ray scattering. Finally, multiphase NMR unambiguously demonstrated the coassembly of PAs bearing the IKVAV moiety with those displaying a peptide that mimics fibroblast growth factor 2, which was necessary to reverse paralysis.