This material uses energy from ambient light to kill hospital superbugs

In lab tests, the quantum dot polymer nearly eliminated two drug-resistant strains of bacteria


STERILE SURFACES  A newly developed coating uses overhead light to trigger bacteria-killing molecules and could be used in hospitals to help stop the spread of some infections.

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PHOENIX — A new material that harnesses the power of ambient light to produce bacteria-killing molecules could help stem the spread of hospital infections, including those with drug-resistant bacteria.

About 1 in 10 patients worldwide get an infection while receiving treatment at a hospital or other health care facility, according to the World Health Organization. “Contaminated hospital surfaces play a key role in spreading those infections,” said Ethel Koranteng, a chemist at University College London, on April 5 at the Materials Research Society spring meeting.

Koranteng and colleagues developed a material to make hospital surfaces self-disinfecting. Naturally antimicrobial metals such as copper and steel are difficult to sculpt around uneven surfaces. But the new polymer-based material could be fashioned into a flexible film that covers computer keyboards, or molded into rigid, plasticlike casings that enclose phone handles, bedrails and other surfaces especially prone to contamination.

Unlike other polymer-based antimicrobial coatings that rely on a spritz of water to release bug-killing particles, the new material is activated by overhead lighting (SN: 2/3/07, p. 75).

The covering is made of polyurethane embedded with tiny semiconductor nanoparticles called quantum dots and particles of a purple dye called crystal violet (SN: 7/11/15, p. 22). When the quantum dots absorb ambient light, they transfer some of that energy to nearby dye particles, causing the crystal violet to release a kind of high-energy oxygen molecule that kills microbes. 

In lab tests, the material killed 99.97 percent of MRSA, the strain of Staphylococcus aureus that is resistant to methicillin and other antibiotics, and 99.85 percent of a multidrug-resistant strain of E. coli. For both experiments, the researchers used much higher concentrations of microbes than those typically found on hospital surfaces, Koranteng said.

Previously the staff writer for physical sciences at Science News, Maria Temming is the assistant managing editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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