Unfolding the Future - The Functional Fold: Amyloid Structures in Nature - page 164

It is clear that when considering the functional or pathogenic
nature of amyloid, the local environment will be a critical
determining factor. In other words, primarily functional amyloid can
be altered under certain conditions to become disease-associated
amyloid. As has been highlighted by Maji

9

several endocrine
hormones that may be stored in an amyloid-like state are present
as amyloids in amyloid diseases such as amylin, which is associated
with type II diabetes. Cross-seeding of amyloids between different
protein species have also been reported.

et al. ,

These issues are likely to
be considered in significantly more depth as researchers attempt to
utilize amyloid as a functional biomaterial within the human body.

16

10.5 Applications of Functional Amyloid

Prior to the recent emergence of widespread functional amyloid,
amyloid fibrils were already being considered as a useful material
for applications in nanotechnology and bioengineering. This is
due to their generic characteristics of chemical, mechanical, and
thermal stability as well as their ability to readily self-assemble.
Demonstrated potential uses have included implating metal
nanowires

17,18

and tissue engineering scaffolds, to promote cell
adhesion and growth.

19
The discovery of a broad range of functional amyloid materials
further extends the possible range of applications via the mimicking
of these structures to produce a new generation of functional
biomaterials. On the basis of nature's own application of functional
amyloid, potential biomimetic uses include lubricants (Chapter 2),
adhesives (Chapter 8), silks (Chapters 4 and 5), and coatings (Chapter
3). In a number of these applications the mechanical properties
of the fibrils (or in some cases fibre composite materials) are of
primary functional importance. Nanomechanical measurements
have helped shed light on the beneficial mechanical characteristics
of functional amyloid fibrils

20

(Chapter 8). It has also been shown
that amyloid fibrils assembled from short peptide segments

have measured rigidities close to the maximal values expected for
defect-free structures of near crystalline order.

in vitro

21

However, in the
design of lubricants and adhesives, the mechanical characteristics
of crystalline materials are not those which the materials scientist
would select and it remains to be established whether the defects