Nature manufactures numerous machines known as “molecular”. Highly complex assemblies of proteins, they are involved in essential functions of living beings such as the transport of ions, the synthesis of ATP (the “energy molecule”), and cell division. Our muscles are thus controlled by the coordinated movement of these thousands of protein nano-machines, which only function individually over distances of the order of a nanometer. However, when combined in their thousands, such nano-machines amplify this telescopic movement until they reach our scale and do so in a perfectly coordinated manner. Even though synthetic chemists have made dazzling progress over the last few years in the manufacture of artificial nano-machines (the mechanical properties of which are of increasing interest for research and industry), the coordination of several of these machines in space and in time hitherto remained an unresolved problem.
Not anymore: for the first time, Giuseppone's team has succeeded in synthesizing long polymer chains incorporating, via supramolecular bonds (1), thousands of nano-machines each capable of producing linear telescopic motion of around one nanometer. Under the influence of pH, their simultaneous movements allow the whole polymer chain to contract or extend over about 10 micrometers, thereby amplifying the movement by a factor of 10,000, along the same principles as those used by muscular tissues. Precise measurements of this experimental feat have been performed in collaboration with the team led by Eric Buhler, a physicist specialized in radiation scattering at the Laboratoire Matière et Systèmes Complexes (CNRS/Université Paris Diderot).
These results, obtained using a biomimetic approach, could lead to numerous applications for the design of artificial muscles, micro-robots or the development of new materials incorporating nano-machines endowed with novel multi-scale mechanical properties.
© Wiley-VCH Verlag GmbH & Co.KGaA. Reproduced with permission. This image is available from the CNRS photo library, firstname.lastname@example.org
From left to right: The principle of contraction and extension of a telescopic polymer chain based on the supramolecular association of thousands of nano-machines. Centre: Molecular model of three nano-machines bonded together within the polymer chain.
(1) A supramolecular bond is an interaction between different molecules that is not based on a traditional “covalent” chemical bond but instead on what are known as “weak interactions”, thereby constituting complex molecular structures.
Muscle-like Supramolecular Polymers – Integrated Motion from Thousands of Molecular Machines, G. Du, E. Moulin, N. Jouault, E. Buhler, N. Giuseppone, Angew. Chem. Int. Ed. On line on the 18/10/2012 (DOI: 10.1002/ange.201206571).