In living memory

Researchers at the University of California, Los Angeles have developed a digital memory device by incorporating platinum nanoparticles into the tobacco mosaic virus.


Researchers at the University of California, Los Angeles (UCLA) have developed a digital memory device by incorporating platinum nanoparticles into the tobacco mosaic virus. They claim that the result could be used to develop biocompatible electronic equipment.



In recent years researchers have exploited the unique selectivity of biomaterials by nanostructuring biological molecules with inorganic materials for applications such as biosensing. The UCLA researchers have taken this idea one-step further with a hybrid biological system that can store digital information.



‘We have developed an electronic device, fabricated from the tobacco mosaic virus conjugated with nanoparticles, which exhibits a unique memory effect,’ said Yang Yang, the group’s lead researcher. ‘This device can be operated as an electrically bi-stable memory device whose conductance states can be controlled by a bias voltage. The states are non-volatile and can be digitally recognised.’



The TMV is a 300nm tube consisting of a protein shell and RNA core. According to the researchers, the TMV’s thin, wire-like structure makes it suitable for attaching nanoparticles, in this case, around sixteen positive platinum ions per virion. The device works by transferring charge, under a high electric field, from the RNA to the platinum nanoparticles with the TMV’s surface proteins acting as an energy barrier, stabilising the trapped charges.



‘The TMV’s surface makes it an ideal template for organising the nanoparticles, which can bind to the specific carboxyl or hydroxyl sites on the surface,’ said Yang. ‘The RNA core in TMV is likely to serve as the charge donor to the nanoparticles with the coat proteins acting as the barrier to the charge transferring process.’



The TMV hybrid, says the team, has an access time in the order of microseconds. This is comparable to current flash memory. In addition, the device is non-volatile, which means that data is retained once the computer’s power is turned off.



The researchers say the device still needs to be scaled-down to a smaller size to increase storage density and to include more circuitry. ‘There will be issues involving retention time, power consumption, and integration of drivers required to write and read each bit, which we need to consider in order to optimise the system,’ said Yang.



Such devices could one day be integrated in biological tissues for applications in therapeutics or biocompatible electronics.