The chemical engineering professor at the Massachusetts Institute of Technology heads a team that's researching electrospinning, a process by which fibers that are a thousand times thinner than a human hair can be spun by using an electrical charge. The silky, tissue-like material that results has a range of potential uses. It can be embedded with chemical molecules to trap and kill bacteria and viruses in disposable face masks.
Most disposable masks used by the public in various parts of the world during the current swine flu epidemic don't carry germ-fighting nanofilters. Using electrospun fibers in the masks may boost their protective power. The fibers also could be used in protective clothing and in other ways.
Rutledge has pioneered electrospinning as a means to create nanofibers since the early days of nanotech's emergence in the late 1990s. He recently spoke with Investors Business Daily (IBD) about using electrospun fiber masks to combat swine flu and more.
IBD: What is your research team trying to do?
Rutledge: We are funded by the U.S. Army and by DuPont (DD) on this project. We're developing protective materials for both chemical and biological warfare agents. But we think these also have civilian applications. So when we make fibers that are designed to be chemically protective materials, they might not be just for military use but also might be for first responders and other civilian applications.
IBD: What applications do electrospun fibers have that let them combat diseases like swine flu?
Rutledge: On bactericidal fibers (or germ-killing fibers), the first target was bacteriological warfare. The thinking here is that you can make not just masks, we're also thinking in terms of multilayered fabrics that could be part of a protective suit. So clothing and masks could be for full-body protection or just for selected areas.
IBD: So, part of your research includes creating filter-type masks that can protect against airborne illnesses?
Rutledge: Yes. The materials made (through electrospinning) are by nature filtration-type materials. But they may not work in the way you normally think.
You normally think of filtration as a sieving process where you would try to make the holes in the material so small that nothing gets through.
IBD: Are there different ways to filter different germs?
IBD: How do you filter out swine flu and other flu-type viruses?
Rutledge: We haven't targeted viruses, so I'm not going to claim that I'm a virus expert. But what I do know is that viruses are typically smaller than bacteria maybe one-tenth of a micron in size. (One micron equals a millionth of a meter.) So you have a filter that doesn't act so much like a sieve (but instead lets them get part of the way through). The structure of the nanofilter is such that when a virus bounces off or encounters a fiber, it can be captured and killed.
IBD: To kill the virus, could the fiber be embedded with a substance such as iodine crystals?
Rutledge: Yes. In order for a virus threat to get through the material, it would first have to navigate a series of fibers (that have been treated with chemicals).
IBD: Is the filtering process for bacteria different?
Rutledge: Yes. In the case of bacteria you can actually filter them out because they're large enough. The thing that makes these fibers particularly useful for fighting bacteria is that not only are the fibers small typically below 1 micron in diameter but because the distance between fibers is also similarly small. Everything scales down. So if you are a typical bug or bacteria, this material traps those things.
IBD: Would you kill the bacteria the same way you kill viruses?
Rutledge: Yes. We would functionalize the fibers chemically so you not only trap (the bacteria), you also kill them with bactericide.
IBD: Why haven't electrospun fibers been used more widely as epidemic-fighting disease masks?
Rutledge: I can only speculate on that. I don't know to what extent (the masks) are out there or not. A lot of the major filtration companies are making these nanofilters. But no doubt, there's a cost issue involved. The volume of people using such products has to go up to make them cheaper.
IBD: What else is delaying the use of these nanofibers as products?
Rutledge: The real interest in (these filters) is associated with the boom in nanotechnology about 10 years ago. That's what got funding in this area to pick up, and that's when university research labs got involved. There's a lag between the time these ideas are first talked about and when they start getting to companies and hitting the shelves.
IBD: Are nanofilters used anywhere today?
Rutledge: They're already used as HEPA, or high-efficiency particle accumulation, filters found in vacuum cleaners and tanks. The U.S. military's been using them as air and fuel filters in military vehicles for a long time.
IBD: What other uses are on the horizon for these nanofibers?
Rutledge: You can use them as substrates for (chemical reactions).
IBD: How do you make electrospun fibers?
Rutledge: Electrospinning uses an electrical charge to draw the fiber from a liquid polymer. As a jet of charged fluid polymer sprays out the bottom of a nozzle, an electric field forces the stream to whip back and forth. This stretches the fiber lengthwise so its diameter shrinks from 100 microns to as little as 10 nanometers.
IBD: Will there be more widespread adoption of nanofibers in fighting disease?
Rutledge: I believe so, generally for high-efficiency filtration. And I think you'll see more of these kinds of materials in (disease-fighting) masks.