Nano-switch for bio-silicon communication
Against the odds, European researchers have developed a versatile molecular switch which could play a key role in vast nanotechnology applications, including motors, relays and biosensors. The EU-funded Mol-Switch project recently unveiled a working model, reports IST Results.
Despite scepticism in the scientific world, English, French, Italian, Dutch and Czech scientists have been constructing a single-molecule DNA-sequencing device and accompanying nano-switch based on a biological molecular motor and a moving magnetic bead. According to the team, the secret to success was in the ‘microfluidics chip' with its tiny (nano-scale) channels moving in a predictable fashion.
The floor of this channel is peppered with ‘Hall-Effect' sensors, accurately describing how a magnetic field influences an electric current. 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 fixed to the floor of the microfluidic channel. This strand is held upright – picture 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.
A specific type of protein, called a Restriction-Modification enzyme, provides one of the DNA motors. This type of DNA motor will only bind to a specific sequence of the DNA bases (A, C, G and T). “This binding is very specific,” Mol-Switch's coordinator Dr Keith Firman of Portsmouth University told IST Results. “A motor will bind only with its corresponding bases, so you can control exactly where the motor is placed on the vertical DNA strand,” he says.
The motor is attached to the strand at the specific sequence of bases. Then the team introduces ATP, the phosphate molecule that provides energy within living cells, into the microfluidics channel. This is the fuel for the motor. The motor then pulls the upright DNA strand through it until it reaches the magnetic bead, like a winch lowering a weather balloon.
As far as the imagination can see
For example, it could be put to use in biosensors, flow-control valves, relays and advanced prosthetics. In addition, the magnetic bead attached to DNA can be used in the single-molecule DNA sequencing apparatus (to overcome coiling due to entropy) and for monitoring the movement of the DNA molecule.
It could one day be used as a communicator between the biological and silicon worlds, providing an interface between muscle and external devices used for implants, for example. A bonus application is in DNA sequencing – in this case, actually mapping the order of the four DNA-bases, which is a core step for genetic research.EU