Biomedical Engineering Reference
In-Depth Information
1.2
A Fabrication Tool: Nanobiotechnology Through Molecular Self-Assembly
Design of molecular biological nanostructures requires detailed structural
knowledge to build advanced materials and complex systems. Using basic
biological building blocks and a large number of diverse peptide structural
motifs [1, 2], it is possible to build new materials from the bottom up. Molecu-
lar self-assembly is ubiquitous in nature, from lipids that form oil droplets
in water and surfactants that form micelles and other complex structures in
water to sophisticated multiunit ribosome and virus assemblies. These sys-
tems lie at the interface of molecular and structural biology, protein science,
chemistry, polymer science, materials science and engineering. Many self-
assembling systems have been developed, which range from organic supra-
molecular systems, bi-, tri-block copolymers [3], and complex DNA struc-
tures [4, 5], simple and complex proteins [6-8] to peptides [9-22].
1.3
Basic Engineering Principles for Micro- and Nano-Fabrication
Based on Molecular Self-Assembly Phenomena
Programmed assembly and self-assembly are ubiquitous in nature at both
macroscopic and microscopic scales. The Great Wall of China, the Pyramids
of Egypt, the schools of fish in the ocean, flocks of birds in the sky, pro-
tein folding and oil droplets on water are all such examples. On the other
hand, self-assembly describes the spontaneous association of numerous in-
dividual entities into a coherent organization and well-defined structures to
maximize the benefit of the individual without external instruction. If we
shrink construction units by many orders of magnitude into nano-scale, such
as structurally well-ordered protein fragments, or peptides [21], we can ap-
ply similar principles to construct molecular materials and devices, through
molecular self-assembly and programmed molecular assembly.
1.4
Both Chemical Complementarity and Structural Compatibility
for Bionanotechnology
The “bottom-up” approach, by which materials are assembled molecule by
molecule (and in some cases even atom by atom) to produce novel supra-
molecular architectures is a powerful technology. This approach is likely to
become an integral part of materials manufacture and requires a deep un-
derstanding of individual molecular building blocks and their structures,
assembly properties and dynamic behaviors. Molecular self-assembly inter-
actions typically include hydrogen bonds, electrostatic attractions, and Van
der Waals interactions. Although these bonds are relatively insignificant in
