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One of the central themes of nanotechnology is the scaling down of electromechanical devices or machines to the molecular scale. In this project, we pursue this goal with the help of nanomachine systems that nature has already created: “biomotors” or “molecular motors”.

The biomotors Myosin V and Kinesin walk along their filaments (actin and microtubules respectively), powered by ATP hydrolization. (Ronald Vale UCSF)

Within every living cell is a complex highway system of tiny motors that move along filamentous tracks. Biomotors and the tracks they move on are ubiquitous in the myriad processes occurring with in the cell. They are responsible for muscle contraction, cell division, and transport of vesicles. They also power bacteria’s flagella and the cilia within our lungs. These systems serve a host of other cellular functions, many of which we are only beginning to understand. For example, these “highway systems” which serve structural, transport and motility purposes, may also provide a communication function across the intercellular environment.

What are Biomotors?

Biomotors are in a sense the ultimate nanomachines. They do mechanical work through the hydrolization of ATP: the energy source of the cell. During hydrolization of ATP, a shape change occurs within the motor protein (a mechano-chemical process), and mechanical work is done. This mechanical work is used to move the motor along a track in order to perform a load transport function, or to apply forces to the filament for cell motility and cell division. The figure above right shows two of the motor/filament systems we are studying: MyosinV/Actin and Kinesin/Microtubule. Both of these motors are known as “processive” motors, which means that they have two “legs” that “walk” along their respective filament tracks.

Biomotors for Nanotechnology

As nanotechnologists we are interested in the design and construction of nanoscale electrical and mechanical devices that provide unprecedented functionality. In developing these systems, we are inevitably faced with the problem of actuation and transport, as well as the need to power these systems and couple them to electronic circuitry. Nature has already provided remarkable solutions to parts of this problem, supplying us with molecular motors powered chemically by individual ATP molecules.

In this project we study the control over molecular motors with an engineering applications perspective, exploring ways in which these incredible machines can be used in designed systems. Our goals are to:

Fluorescence microsopy showing Actin filiaments (white) alignment through dielectrophoresis. Metal electrodes appear dark (Sreeja Padmanabhan).

1) Demonstrate the control of the patterning of motor raceways as functioning tracks for the motion of motor proteins (see figure to right)

2) Study the two of the main classes of proteins actin/myosin and microtubule/kinesin to understand their relative merits towards nanotechnology applications.

3) Study the application of single motors and collections of motor proteins and

4) Study the coupling of nanotubes to electrical circuitry through electro/dielectrokinesis at the nanometer scale

5) Understand a processing methodology for incorporating nanometer scale e-beam lithography, nanotube placement/growth, patterned chemical functionalization and motor binding and motility. These capabilities and fundamental characterizations will be applied to new force sensing analyzing devices and multiplexing arrays. This research program will closely couple nanoscale engineering with the basic science of motor proteins.

Physics, Biology, Physiology, Computer Science

Progress in these projects requires expertise and experience in many different scientific disciplines. Our cross disciplinary team includes investigators from the departments of Physics and Astronomy, Biology, Cell and Molecular Physiology, and Computer Science. The project is currently supported by the National Science Foundation through a 3-year grant.

More Information and Useful Links

Questions and comments should be sent via email to Richard Superfine .

Collaborating Investigators Web Sites:

· Richard Cheney

· Ted Salmon