Biomedical Engineering Reference
In-Depth Information
Introduction
Xian Jun Loh
The rapid growth of supramolecular chemistry has led to the development of novel
materials which are built based on the theory of self-assembly on the molecular
level. Whitesides and Grzybowski [
1
] defined self-assembly as “the autonomous
organization of components into patterns or structures without human interven-
tion”. The idea of building up an ordered structure from a mass of disordered indi-
vidual subunits is immensely intriguing. From the building of order from disorder
to the emergence of novel properties from self-assembled structures not observed
in individual subunits, there are interesting scientific questions that draw research-
ers to this field. The science of supramolecular chemistry is intrinsically reliant
on the connecting moieties, their specific association/dissociation and the thermo-
dynamics of the process. The bulk properties can be greatly affected by the indi-
vidual components, either having an environmental response, varied mechanical
properties as well stability. Self-assembled built-up materials have been exten-
sively reported for several years, these exist in the form of vesicles, micelles and
hydrogels.
Vesicles are molecular containers made up of a thin membrane encasing a vol-
ume. Vesicles have attracted great research interest as they are important building
blocks resembling the cellular units that make up most organisms and are useful in
chemistry, biology, and material science [
2
-
4
]. They have wide applicability and
can be used as drug/gene delivery systems, for the study of the function of ion
channels and also light-harvesting systems. Synthetic vesicles are typically derived
from amphiphiles with different polar or hydrophilic head groups and hydrophobic
tails. Polymeric micelles are yet another type of encapsulating agents that are built
up from the self-assembly of amphiphilic polymers [
5
]. Polymeric micelles have
been used in a variety of applications including purification of wastewater [
6
],
templating agents for materials synthesis, biologically relevant nanobioreactors
