Switch between biological and silicon worlds
| Scientists have created a molecular switch that could play a key role in thousands of nanotech applications. The Mol-Switch project successfully developed a demonstrator to prove the principle, despite deep scepticism from specialist colleagues in biotechnology and biophysics. "Frankly, some researchers didn't think what we were attempting was possible because standard descriptions in physics, for example the Stokes equation for viscosity indicated that the system might not work. But viscous forces do not apply at the nano-scale," says Dr Keith Firman, Reader in Molecular Biotechnology at Portsmouth University and coordinator of the Mol-Switch project, funded under the European Commission’s FET (Future and Emerging Technologies) initiative of the IST programme. "However, we got our molecular switch to work." The upshot is that the Mol-Switch project was far more successful than expected. The team's switch works with a number of DNA-based motors and can achieve incredible performance. Specific sensors, which emit electrons, can tell if the biological motor is working, so the switch links the biological world with the silicon world of electronic signals. Here's how it works. The team uses a microfluidics chip that includes a number of channels measured in nano-metres. The novelty of microfluidics is that it can channel liquids in laminar, or predictable, flow. The floor of this channel is peppered with Hall-Effect sensors. The Hall Effect describes how a magnetic field influences an electric current. That influence can be measured to a high degree of accuracy. These measurements link the biological motor with the electronic signals of the silicon world. The biological element of the device starts with a DNA molecule that's fixed to the floor of the microfluidic channel. This strand is held upright, like a string held up by a weather balloon, by anchoring the floating end of the DNA strand to a magnetic bead, itself held up under the influence of magnetism... "The light switch, the button that makes a retractable pen, all these are actuators, and by developing a molecular switch we've created a tiny actuator that could be used in an equally vast number of applications," says Firman. This is particularly important because a nano-scale actuator will be immensely useful. An actuator is a mechanism that supplies and transmits a measured amount of energy for the operation of another mechanism or system. It can be a simple mechanical device, converting various forms of energy to rotating or linear mechanical energy. Or it can convert mechanical action into an electrical signal. It works both ways. The number of potential applications is staggering. They can be used for flow-control valves, pumps, positioning drives, motors, switches, relays and biosensors. The system could be used to develop molecular circuits, or even molecular scale mechanical devices. The potential applications are difficult to predict, but are only limited by the imagination of researchers, such is the versatility of an actuator on this scale. "It could be used as a communicator between the biological and silicon worlds. I could see it providing an interface between muscle and external devices, through its use of ATP, in human implants. Such an application is still 20 or 30 years away," says Firman "It's very exciting and right now we're applying for a patent for the basic concepts." One hugely important application is DNA sequencing, discovering the order of the four DNA-bases, the absolutely fundamental step for genetic research. This is almost a 'bonus' application, a happy side effect of the actuator's operation. The team used the Mol-Switch with time-resolved fluorescence for DNA sequencing. Read more... This was seized 4 u at Information Society Technologies |
posted by Roland at 4/24/2006 10:48:00 AM
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