Nanofibrous scaffold from self-assembly of beta-sheet peptides containing phenylalanine for controlled release.

Scaffold nanostructures from self-assembly of beta-sheet peptides, RADAFI and RADAFII, containing same amino acid compositions but different positions of one phenylalanine residue, were investigated. Atomic force microscopy (AFM) images clearly showed that peptide RADAFI self-assembled into twisted nanofibers with multiple molecular sized width and height, but no twisted nanofiber, characterized by a stacked bilayer model with single molecular sized width, was obtained in RADAFII scaffold. Two models of the hierarchical self-assembling behaviors could be illustrated for RADAFI and RADAFII scaffolds. The peptide scaffolds might also be promising for a variety of possible biomedical applications, including drug delivery, and the results revealed some relationships among the peptide sequence, the network nanoarchitecture, and the controlled release. From the remarkably large difference between the architecture and properties of the self-assembling materials based on the two similar peptides, it could be concluded that the self-assembly behaviors were delicate and could be dramatically altered by small modifying peptide structural features due to subtle changing the phenyl group position. The presence of a center pi-pi stacking between two beta-sheet-forming strands in the peptide sequence was demonstrated to be an important factor in promoting the twisted nanofiber morphology and a stronger network. Also, the concept of dominating the network nanostructures could be harnessed in the de novo design of delivery materials for some special biomolecules.