Virus boosts nanoparticle memory
Oct 4, 2006
A new type of digital memory device has been created by incorporating inorganic platinum nanoparticles into the tobacco mosaic virus (TMV).
The work was done by researchers at the University of California, Los Angeles (UCLA), who claim that the result could find application in the development of bio-compatible electronics (Nature Nanotechnology 1 72).
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,” Yang Yang, the group’s lead researcher at the University of California, told physicsweb.org. “This device can be operated as an electrically bistable memory device whose conductance states can be controlled by a bias voltage. The states are non-volatile and can be digitally recognized.”
The TMV is a 300 nm tube consisting of a protein capsid (outer shell) and RNA core. According to the researchers, the TMV’s thin, wire-like structure makes it suitable for attaching nanoparticles. In this case, it allowed them to add an average of sixteen positive platinum ions per virion. The device works by transferring charge, under a high electric field, from the RNA to the Pt 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 organizing 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 ( the delay between a call for storing data and for data storing to begin) in the microsecond regime. This is comparable to today’s 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 optimize the system,” said Yang.
In the long term, these devices could one day be integrated in biological tissues for applications in therapeutics or biocompatible electronics.
About the author
Darius Nikbin is a freelance science writer based in the UK