Designer Self-Assembling Peptide Nanofiber Scaffolds - Nanotechnology for Biology and Medicine - page 132

Fig. 8 Self-assembling peptide RADA16-I nanofi ber scaffold hydrogel. ( To p ) Molecular model of
RADA16-I. ( Left ) Molecular model of a single RADA16-I nanofi ber with its dimensions being
~6 nm long, 1.3 nm wide and 0.8 nm thick. Many individual peptides self-assemble into a nanofi ber.
( Right ) SEM images of RADA16-I nanofi ber scaffold. Scale bar, 0.5 m m

from their ability to stabilize a number of membrane proteins and membrane protein
complexes (Kiley et al. 2005 ; Yeh et al. 2005 ; Zhao et al. 2006 ). Interested readers
can consult the original reports and a recent summary (Zhao and Zhang 2006 ).

4.2 Self-Assembling Peptide Nanofi ber Scaffolds

A single molecule of the ionic self-complementary peptide RADA16-I is shown in
Fig. 8 . Millions of peptide molecules spontaneously undergo self-assembly into
individual nanofi bers that further form the scaffold (Fig. 8 ). Between the nanofi bers,
there are numerous nanopores. The nanopores range from a few to a few hundred
nanometers. Such structuring is similarly sized as most biomolecules and allows
only slow diffusion of molecules within the scaffold and can be used to establish a
molecular gradient. Figure 9 shows the individual nanofi bers ranging from a few
hundred nanometers to a few microns. Peptide samples in aqueous solution using an
atomic force microscopy (AFM) examination display nanofi bers (Fig. 9b-d ), which
at high resolution appear to have distinct layers in some of their segments (Fig. 9d )