Nano-storage wires

(Nanowerk Spotlight) Nanowires are considered a major  building block for future nanotechnology devices, with great potential for  applications in transistors, solar cells, lasers, sensors, etc. (see for instance: “Nanowires  for the electronics and optoelectronics of the future” and “Nanotechnology explained:  Nanowires and nanotubes”).

Now, for the first time, nanotechnology researchers have  utilized nanowires as a ‘storage’ device for biochemical species such as ATP.   Led by Seunghun Hong, a professor of physics, biophysics and chemical  biology at Seoul National University, the team developed a new nanowire  structure – which they named ‘nano-storage wire’ – which can store and release  biomolecules.

Reporting their findings in the July 16, 2013 online edition of  ACS Nano (“Nano-Storage Wires”), Hong’s group demonstrated  that their nano-storage wire structure can be deposited onto virtually any  substrate to build nanostorage devices for the real-time controlled release of  biochemical molecules upon the application of electrical stimuli.

“Our nano-storage wires are multisegmented nanowires comprised  of three segments and each segment plays a role in extending the applications of  the nanowire,” Hong explains to Nanowerk: “1) the conducting polymer segment  stores biomolecules; 2) the nickel segment allows the utilization of magnetic  fields to drive the nanowires and place them onto a specific location for device  applications; and 3) the gold segment enables a good electrical contact between the deposited nano-storage  wires and the electrodes. The polymer segment is utilized for the controlled  release of ATP molecules. The nickel segment enables the magnetic localization  of nano-storage wires, while the gold segment provides a good electrical contact with electrodes.”

Left:  Schematics of a nano-storage wire. Right: SEM image of a single nano-storage  wire. The dark, intermediate, and bright regions represent PPy-ATP (conducting  polymer with ATP molecules), nickel, and gold segments, respectively. (Images:  Dr. Seunghun Hong, Seoul National University)    The released biomolecules from such a nanowire-storage system  can be used for instance to control the activity of biosystems. As a proof of concept, the researchers stored  ATP in their nano-storage wires and released it by electrical stimuli, which  activated the motion of motor protein systems. The team also demonstrated flexible nanostorage devices. Here, nano-storage wires were driven by magnetic  fields and deposited onto nickel/gold films on a transparent and flexible  polyimide film. The device  transmitted some light, and it can be easily bent. They also showed that the nanowires could be deposited onto  curved surfaces such as the sharp end of a micropipet.       

    

SEM  image of nano-storage wires deposited on a micropipet. (Reprinted with  permission from American Chemical Society)   

“Such probe-shaped storage devices can be used for the delivery  of chemicals to individual cells through a direct injection,” says Hong.  “Basically, our results show that nano-storage wires are quite versatile  structures and we  can deposit them onto virtually any structure to create nanoscale devices for  the controlled release of biochemical materials.”

“Nano-storage wires will allow the fabrication of advanced  biochips which can activate or deactivate the activities of biosystems in real  time,” Hong points out. “The activation and deactivation of biosystems such as  biomotors, are controlled by specific biomolecules. In our method, we can  selectively control the biomolecular activities related with ATP or any released  chemical species while leaving other biomolecular activities unaltered.”

Having demonstrated the storage of ATP, the team is now planning  to store other  biomolecules in our nano-storage wires. Examples are drugs to control the  activity of cells and tissues, enzymes to activate specific signal pathways in  biosystems etc. “Eventually, we would like to build an advanced biochip which  can be utilized to control the activities of desired biosystems in real-time,” says Hong.

By Michael Berger. Copyright © Nanowerk

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