PEPTIDE SELF-ASSEMBLY BIOMATERIALS DESIGN AND APPLICATION - Biologically-Responsive Hybrid Biomaterials - page 84

Reches and Gazit have demonstrated using the shortest peptide, a Phe-Phe
dipeptide can form stable nanotubes [26] . By diffusing silver ions into the well-
formed tubes, then removing the peptide either enzymatically, chemically, or
through heat burning, the silver wire was revealed.
Amyloid protein nanofibers have also been used as scaffold to align gold
nanocrystals. Scheibel, Lindquist and colleagues reported that a bioengineered
prion-determining (NM) domain of yeast prion protein Sup35 provided a
scaffold for fabricating nanowires. They also tested the conducting capability of
the resulting wires [27] .

A B C

Fig. 8. (A) Schematic three-dimensional molecular model of P9: (AC- PSFCFKFEP -NH2). In this
conformation, all of the hydrophobic phenylalanine side chains face in one direction, and the
residues of serine, asparagine, lysine and glutamic acid side chains face in the other direction to
create two distinct faces. The dimensions are about 3.1 nm long, 1.2 nm in height and 0.4 nm thick.
(B) The far-UV CD spectra of the peptide (200 Ⱥ M) at different sodium chloride concentrations
from 190 to 260 nm were shown: pure water ( ■ ); 0.5 mM sodium chloride ( □ ); 5 mM sodium
chloride ( ▲ ); and 1 M sodium chloride ( △ ). (C) TEM images of the peptide at 0.2 mg/mL. (a)
Low magnification (25,000-fold), showing high-density fiber networks. (b) Higher magnification
(60,000-fold) for a single fiber, and the fibrils were twisted together to form fibers. The scales are
marked in each panel.

Belcher and colleagues take a very different approach, not only to discover
but also to fabricate electronic and magnetic materials, departing sharply from
the traditional materials process technology [27-30] . Their strategy is to genetically
engineer self-assembling bacteriophage so that they can be used to select
conducting, semi-conducting and magnetic materials. They have also evolved the
phages (and other microbial organisms) for additional material fabrications. This
strategy might lead to the discovery of new electronic and magnetic materials.

8. Future Trends in Nanobiotechnology

One of the trends in nanobiotechnology is the development of new biological
materials and nanobiotechnologies that in turn often broaden the questions we