Keeping clean with light

New research from UC Davis scientists reveals how useful a self-cleaning fabric – more specifically, cotton – can be for many professions. The fabric is able to fight off bacteria as a result of its production of hydrogen peroxide.

“When we put the chemical on the fabric and then put it into the light, hydrogen peroxide is produced,” said Gang Sun, professor of textiles and clothing at UC Davis.

According to Sun, the chemical he and his colleagues used is called 2-anthraquinone carboxylic acid, which is able to bond chemically to fabrics. He said that one of the advantages of this chemical is that it can be put into the dyes that are used in clothing, allowing for an easier method of incorporation of the chemical with the fabric.

“When the molecules in the chemical absorb different electromagnetic wavelengths, they become excited and jump to becoming excited molecules, which allows for interaction with oxygen,” Sun said.

He said that it is this interaction in which molecules become excited as a result of absorbing visible light that produces the bacteria-fighting effect.

“The fact that it is environmentally-friendly and doesn’t need anything but light means we can do this to other polymers as well,” Sun said.

He believes that there could be many more applications for this chemical, even though durability of the chemical on the fabrics is uncertain. One of the concerns is that scientists do not know how much light the fabric can be exposed to before the chemical’s effects begin to dwindle.

“We tested it under certain conditions, but not all. One of problems is that every time you expose it to light, the durability and efficacy may be reduced,” Sun said.

Ning Liu, a doctoral researcher in Sun’s group, said that the efficacy of the chemical could decline at a faster rate for people who work outside.

“It is expected that the chemical will lose its function faster for people who work outside because sunlight is much more powerful,” Liu said.

Even though the chemical is expected to lose its function faster in outside environments, it is also the place where the chemical is expected to produce its best effects.

“Normal indoor lighting works, but the chemical works better when outside because the chemical becomes more powerful as a result of the sunlight,” Liu said.

In terms of the fabric being washable, Liu said that the fabric could be washed without worry, since the chemical is bound to the fabric.

She believes that this self-cleaning fabric can be of particular use for the medical and agricultural industries.

“It is advantageous for farmers who come in contact with pesticides, but also for medical professionals,” Liu said.

According to the California Department of Public Health, Healthcare-Associated Infections (HAIs) often plague patients and hospitals.

“[HAIs] are the most common complication of hospital care, occurring in approximately one in every 20 patients,” states the California Department of Public Health website.

According to Liu, some other good uses of the self-cleaning fabric might be as curtains that surround beds in hospitals or even as the fabric in the living room couch – something which could prove especially useful for households with children.

“It has many applications – we’re not sure what the best fit is,” Liu said.

With Liu’s estimate of the self-cleaning fabric becoming commercially available in three to five years, it is possible that the public may receive an added method of protection against infections.

ERIC C. LIPSKY can be reached science@theaggie.org.

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