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Posted: Nov 29, 2013
Artificially created molecular-level mechanical motion
(Nanowerk News) Scientists demonstrated the highly controlled motion of an artificial molecular motor capable of uni-directional hand-over-hand type movement rarely achieved before. Molecular robots and machines could be around the corner.
Molecular motors are protein machines, enzymes that transform chemical energy into mechanical work, stepping uni-directionally along molecular 'tracks' in a hand-over-hand processive fashion (catalysing successive reactions without releasing its substrate). They are used in nature to serve functions such as muscle contraction, cell division and transport of organelles to their required cellular locations.
As is often the case, nature is a source of inspiration for scientists who are actively researching the possibility of recreating the beauty and functionality of molecular motors to enable the execution of tasks by molecular-level mechanical motion. To date, such recreations have lacked the exquisite control present in biological systems.
The myriad of molecular motors fall into a few classes depending on components, one of which is the kinesin motor that generates linear motion along microtubules. Scientists initiated the EU-funded project 'Synthetic kinesin analogues: A transition metal complex that can walk' (METALWALKER) to develop a fully synthetic molecular kinesin machine capable of sequential processivity, few of which have been demonstrated to date.
In order to achieve such movement, two sets of kinetically stable orthogonal binding units must be present on the walker that can be activated and deactivated separately. The team combined a thermally activated palladium (II) complex and a photochemically activated platinum (II) complex in a single walker unit and successfully demonstrated the two main requirements for operation of the machine, directionality and processivity.
The METALWALKER concept, leading to successful demonstration of an artificial molecular motor, opens the door to development of novel systems to control tasks with molecular-level motion and molecular mechanical machines. Applications include nanorobots and nanodevices for medical applications.