Molecular extension- contraction motion

Fluorescent-labelled oligonucleotides have been applied to the development of photonic logic gates,which may have application in molecular computation. A machine which undergoes extension-contraction motion is described, which is monitored by FRET, between a duplex and a quadruplex structure. The motion is driven by the addition of single-stranded oligonucleotide that causes the quadruplex to collapse and leads to a duplex structure. 

Barboiu M, Lehn JM (2002) Dynamic chemical devices modulation of contraction/extension molecular motion by coupled-ion binding/pH change-induced structural switching. Proc Natl Acad Sci USA 99 5201-5206... 

Another area of NEMS that is receiving tremendous attention is the mimicry of biological systems, aptly referred to as biomimetics. For instance, in the development of linear molecular muscles that undergo contraction and extension movements. Initial work in this field utilized transition metal complexes containing rotaxanes and catenanes, due to the nondestructive redox processes occurring on the metal centers.Though these complexes were actuated by a chemical reaction, the movement was in a noncoherent manner. In order to better mimic skeletal muscle movement, one has to look at the mode of motion within the most efficient molecular machines - in our human bodies. 

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