Molecular machines and motors

One of the most intriguing functional properties of living systems is their capacity to generate collective molecular motions which produce macroscopic responses. For instance, in muscular tissues, the coordinated movements of thousands of myosin heads lead to the gliding of thick myosin filaments along thin actin filaments which result in a cooperative contraction of the entire sarcomere. In that particular case, the individual shifts of the proteins take place in the 10 nm range whereas their integrated translation produces a 1 mm contraction of the sarcomeres, these latter being in turn coupled together, up to producing macroscopic motions. The synthesis of artificial molecular machines and motors is thus of central interest for chemists and physicists in order to mimic their biological counterparts with the long-term aim of engineering dynamic functional materials by bottom-up approaches. However, a particularly fundamental and challenging objective associated to nano-machines remains their coupling (in space and time) in order to transfer controlled motions from the molecular arena to the macroscopic scale. Recently, we have published an important scientific breakthrough showing the four orders of magnitude amplification of the mechanical output of thousands of molecular machines linked within a single-strand supramolecular chain, and transferring reversible contractile motions from the nanometer scale to the ten of micrometers. Recently, we have been even further following these ideas by integrating real molecular motors which are able to work in a non-equilibrium regime when supplied with energy. These molecular motors (see the X-ray structure of one of them on the left) are able to produce a continuous rotary motion when activated by light. By integrating them as reticulation points in networks of polymer chains, we have demonstrated their capacity to produce macroscopic motions in the gel material as a whole (see video below). Here, 8 orders of magnitude are crossed by coupling these active nodes altogether, generating the first metastable material integrating nanomachines and functioning in a thermodynamic state close to what is observed in living systems. Beyond the property of “molecular muscles”, such material is able to convert and store light energy in mechanical energy in the tensed gel, an energy that we are currently trying to make use in a controlled way for actuating other processes.