Supramolecular assembly
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A supramolecular assembly is a well defined complex of molecules held together by noncovalent bonds. While a supramolecular assembly can be simply composed of two molecules (e.g., a DNA double helix or an inclusion compound), it is more often used to denote larger complexes of molecules that form sphere-, rod-, or sheet-like species. The dimensions of supramolecular assemblies can range from nanometers to micrometers. Thus they allow access to nanoscale objects using a bottom-up approach in much fewer steps then a single molecule of similar dimensions.
The process by which a supramolecular assembly forms is called self-assembly or self-organization. Some try to distinguish self-assembly as the process by which individual molecules form the defined aggregate. Self-organization, then, is the process by which those aggregates create higher-order structures. This can become useful when talking about liquid crystals and block copolymers.
Supramolecular assemblies are being investigated as new materials. For instance, Samuel Stupp and coworkers at Northwestern University showed that a supramolecular assembly of peptide amphiphiles in the form of nanofibers could be used to promote the growth of neurons. A great advantage to this supramolecular approach is that the nanofibers will degrade back into the individual peptide molecules that can be broken down by the body.
