Biomedical Engineering Reference
In-Depth Information
isolation, when combined together as a whole, they govern the structural con-
formation of all biological macromolecules and influence their interaction
with other molecules. The water-mediated hydrogen bond is especially im-
portant for living systems, as all biological materials interact with water. It
is a powerful approach for fabricating novel supramolecular architectures,
whichisubiquitousinnatureandhasnowemergedasanewapproachin
chemical synthesis, nanotechnology, polymer science, materials and engin-
eering.
To date, several self-assembling peptide systems have been studied, rang-
ing from models for studying protein folding and protein conformational
diseases, to molecular materials for producing peptide nanofibers, peptide
scaffolds, peptide surfactants and peptide ink [9, 10] easy to produce at a large
scale to drive the development of this new industry. These self-assembly pep-
tide systems represent a significant advance in molecular engineering for
diverse technological innovations. This field is growing at a rapid pace and
it is impossible to summarize all aspects of the work being done by others
in this limited space, and hence this review focuses on a few examples espe-
cially from our laboratory. We focus on our work from the past decade, but
those who are interested in trends over a longer period of time are referred to
earlier reviews [10, 11].
2
Self-Assembly Peptide Systems
A new class of oligopeptide-based biological materials was serendipitously
discovered from the self-assembly of ionic self-complementary oligopep-
tides [3]. A number of peptide molecular self-assembly systems has been
designed and developed. This new class of biological materials has con-
siderable potential for a number of applications, including scaffolding for
tissue repair and tissue engineering, drug delivery of molecular medicine
and biological surface engineering. Molecular self-assembly relies on chem-
ical complementarity and structural compatibility [23]. These fundamentals
are keys to the design of the molecular units required for the fabrication of
functional macrostructures, which in turn permit molecular self-assembly in
nanotechnology and nanobiotechnology.
The complementary ionic sides have been classified into several moduli
(modulus I, modulus II, modulus III, modulus IV, etc., and mixtures thereof).
This classification is based on the hydrophilic surfaces of the molecules,
which have alternating positively and negatively charged amino acids al-
ternating by one residue, two residues, and three residues and so on. For
example, charge arrangements for modulus I, modulus II, modulus III and
modulus IV are -+-+-+-+, --++--++, ---+++ and ----++++, respec-
tively. The charge orientation can also be designed in the reverse orientation,
