What happens when you mix Vitamin C and gold?

Apparently, the answer to the question in the headline has been widely explored by scientists.

What was recently discovered, though, was that a boost of vitamin C can turn small gold nanorods into fine gold nanowires.

"There's no novelty per se in using vitamin C to make gold nanostructures because there are many previous examples," said chemist Eugene Zubarev from Rice University in Texas. "But the slow and controlled reduction achieved by vitamin C is surprisingly suitable for this type of chemistry in producing extra-long nanowires."

Zubarev published his findings in the American Chemical Society journal ACS Nano.

Gold nanowires grown in the Rice University lab of chemist Eugene Zubarev. Photo by Zubarev Research Group.

In the paper, the researcher explains that the nanorods he used are about 25 nanometers thick at the start of the process and remain that way but their length grows to become long nanowires of over 1,000 nanometers.

The process, however, is quite slow as it takes hours to grow a micron-long nanowire. The way it works is that the ascorbic acid provides electrons that combine with gold ions in five-sided rods and settle at the tips in the form of gold atoms.

Zubarev said the wires' aspect ratio -length over width- combined with gold's inherent metallic properties, could enhance their value for sensing, diagnostic, imaging and therapeutic applications.

The scientist and his team also proved that the process is fully controllable, which means that it is possible to produce nanowires of any desired length, and thus the desired configuration for electronic or light-manipulating applications.

"The nanowires' plasmonic response can be tuned to emit light from visible to infrared and theoretically far beyond, depending on their aspect ratios," the experts said in a media statement.