Gold Nanowires Allow Operations at Cellular LevelJohn Simpson | November 17, 2016
A novel device made from gold nanowires may benefit patients during electrode and organ transplant procedures.
The device, developed by Bret Flanders, associate professor of physics, and Govind Paneru, former graduate research assistant in physics, at Kansas State University, uses the gold nanowires to manipulate and sense characteristics of individual cells during medical procedures. The nanowires are 1,000 times thinner than a human hair.
"Conventional surgical tools, including electrodes that are implanted in people's tissue, are unfavorably large on the cellular level," Flanders says. "Working at the individual cellular level is of increasing importance in areas such as neurosurgery."
Flanders says the size of the nanowires is what makes the device unique. Each wire is less than 100 nanometers in diameter. Cells in skin and hair are about 10-20 micrometers in diameter, while red blood cells measure about 7 micrometers. Because the wire is so small, it can pierce a biological cell to stimulate the cell membrane and investigate its interior.
The nanowires are electrochemically grown, meaning they do not grow by lengthening or enlarging an existing wire, but rather by accumulating particles from solution to create a new wire. In heavily zoomed video footage, the nanowire appears to grow out of the micrometer-thick electrode.
"We start with a sharp microelectrode on a microscope stage," Flanders says. "Similar to snowflake formation, the gold atoms condense onto its sharp tip. Like the water condensing onto the snowflake seed, the golden solution condenses onto the gold 'seed,' or the microelectrode."
The researchers develop the sharp electrodes with an unconventional tool not found in many laboratories: a sewing machine. The sewing machine oscillates the microelectrode up and down in a beaker of potassium chloride solution. Application of a voltage dissolves the tip of the microelectrode.
According to Flanders, the process sharpens the electrode because the tip is in the solution longer than any other point. The sharpened electrode allows the nanowire to grow.
The researchers then dismount the nanowire from the electrode and ship it to collaborators across the country, including a nanofabrication company that may incorporate the invention into a pre-existing device to provide it with greater power.