Manipulating Molecular Machines

Single molecule optical microscopy allows researchers to “see and touch” tiny molecular machines measuring only one nanometer.

AsianScientist (Jul 24, 2014) – Scientists have developed a method of visualizing and controlling single molecules, paving the way for the study of molecular machines. This research has been featured on the back cover of the journal Angewandte Chemie International Edition.

Single-molecule imaging and manipulation with optical microscopy could unveil the fundamental properties of biomolecular machines such as direction of motion, step size and the force a molecule exerts, information which cannot be resolved by bulk-molecule measurements. As such, it has become an essential method for research of biomolecular machines. In addition, single-molecule motion capturing could also become a powerful tool for developing synthetic molecular machines.

However, it is difficult to apply conventional methods to individual molecules because the size of a typical synthetic molecular machine is only one nanometer, about one-tenth the size of a biomolecular machine. This miniaturization of the target molecule causes significant problems such as low efficiency of the bead probe immobilization reaction and undesired interaction between the surfaces of the bead and substrate.

Professor Hiroyuki Noji, Dr. Tomohiro Ikeda and Mr. Takahiro Tsukahara at the University of Tokyo, Professor Ryota Iino at the Okazaki Institute for Integrative Bioscience and Professor Masayuki Takeuchi at the National Institute for Materials Science have now captured the motion of a single synthetic machine of about one nanometer in size for the first time.

In this experiment, the researchers resolved the problems in the conventional method which are caused by the small size of the target and successfully visualized the rotational motion of a single double-decker porphyrin (DD) by imaging a magnetic bead attached to the DD. Furthermore, the researchers successfully manipulated the motion of the single DD molecule by applying an external force to the bead.

This method, which allows us to “see and touch” single synthetic molecular machines, provides the only strategy currently available to verify and evaluate the performance of synthetic molecular motors in force generations. It also opens up possibilities for future applications. For example, if it were possible to create a light-driven synthetic molecular motor connected to a biomolecular motor, it should then be possible to establish a tailor-made energy conversion system that can control various chemical reactions by application of light. Therefore, this technique could contribute to development of tailor-made energy conversion systems based on molecular machines.

The article can be found at: Ikeda et al. (2014) Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy.


Source: University of Tokyo.
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