Nanotechnology Research

A coating of fibers too small for the eye to see makes water droplets on a glass sheet act like marbles on a tabletop.

Tilt the glass, and the droplets roll off.

Flip the glass over, where the nanofibers have been treated with chemicals that attract water, and water droplets flatten, turning a foggy glass clear again.

"The chemistry and morphology control the properties of the surface," said Arthur J. Epstein, director of Ohio State University's Center for Materials Research.

Cool? Definitely. Practical? Getting there.

With the right chemicals, these microscopic lawns made up of plastic fibers can make coatings that can repel dirt or oil, or uncoil and hold DNA outstretched for study.

Fibers can conduct electricity and light up plastics. Buried under the skin, they could work as an artificial muscle.

The list goes on.

The research is in the growing field of nanotechnology, a science that manipulates materials at the molecular level to make everything from sun blocks to stain-resistant clothing.

At Ohio State, researchers have built nanoscaffolding on which to grow human tissue, developed a process to squeeze DNA down to a size that might be usable for gene therapy, found that nanoparticles injected in animals might help detect cancer early and begun to develop new materials to gather solar energy.

Epstein's former postdoctoral student Nan-Rong Chiou came up with a process that grows plastic nanofibers -- about one-500th of the width of human hair -- in a uniform pattern.

"Nobody realized you could do that," said Ric Kaner, a professor of inorganic chemistry, materials science and engineering at UCLA and a director of the California NanoSystems Institute.

"People have been trying to figure this out for a number of years."

Under a powerful microscope, the nanofibers resemble a putting green. Chiou mixed weak concentrations of aniline, a component of dyes used in Oriental carpets, with an oxidant called ammonium persulfate.

He dipped a plastic film into the solution, and polyaniline fibers grew on the surface. Polyaniline is a chain that links simple aniline molecules into a complex molecule.

The chemical reaction was halted when the film was rinsed in water. That's when he got his uniform pattern.

"Anything you can do to get them aligned and get them to grow where you want to is a significant advance," said Sanjeev Manohar, a chemical engineering professor at the University of Massachusetts, Lowell.

Manohar has used plastic nanofibers that grow randomly to build tiny transistors. He expects the OSU research to be useful in his work.

"If you have a bunch of wires going one way instead of (resembling) spaghetti, the electronic transport is more efficient."

Kaner said the process holds a lot of promise.

"It's certainly effective scientifically. Whether it makes things cheaper and more accessible, it's hard for scientists to know."

Epstein, Chiou and others at Ohio State are doing more research and have found that they can coat almost any kind of material.

Glass treated with the hydrophobic -- not capable of uniting with or absorbing water -- coating could one day become self-cleaning windows.

With L. James Lee, a chemical and biomolecular engineering professor, the researchers have laid out patterns of hydrophilic and hydrophobic fibers that draw fluids through channels.

Epstein said if you put a light-emitting polymer on top of the nanofiber turf and connect the positive charge from a battery to the turf and the negative charge to the opposite end of the polymer, the device emits light using far less electricity than a traditional incandescent bulb or fluorescent tube.

Nanocoating also can be used to reduce static electricity. Epstein said that a walk across a carpet creates enough static electricity to shock us when we touch a doorknob. That can be reduced by coating a knob or even the soles of our shoes so that electrons are released into the atmosphere.

"You can change the properties so that you can conduct or insulate electricity under the skin, whichever is desired," said Chiou, who is now senior research and development manager for Nanomaterials Innovation Limited, a startup with Lee, with offices at OSU.

Chiou said he is particularly interested in medical uses, including artificial muscles.

When the researchers apply an electric charge to a film, one side can attract or repel ions from polymer fibers. The action changes the length of fibers. Shorten the fibers on one side, and the film curls like a closing fist. Lengthen them and the film extends, like a fist opening. The researchers must determine if the curling and opening action is strong enough to be useful.

The scientists have applied for a patent and expect to work with industry to further develop uses.

The research is funded by the National Science Foundation Center for Affordable Nanoengineering of Polymeric Biomedical Devices.