Silver coating kills superbugs at the nanoscale level

Researchers at Southern Illinois University Carbondale are studying how to zap antibiotic-resistant bugs using electricity on the nano scale, which could lead to fewer infection-related deaths in hospitals.

Punit Kohli, professor in the School of Chemical and Biomolecular Sciences, along with researchers from the departments of chemistry, microbiology, physiology and the SIU School of Medicine, recently published a paper in the journal Science Advances outlining their work. The technology, known as “electrically polarized nanoscale metallic” or “ENM,” involves applying an electrical potential to nanoscale metallic coatings that polarizes the coatings and generates chemicals called reactive oxygenated and chlorinated species. Such substances can deactivate a wide range of harmful microorganisms.

The U.S. Patent and Trademark Office has issued a provisional patent on the technology, Kohli said.

Any surface prone to biological contamination is a target for the technology, Kohli said. So along with potential benefits for the health care setting, the technology might also be applied to a wide range of uses, including in homes, restaurants, public places such as schools, railway stations and airports, and industry.

“It could be incorporated on wearable masks, clothing, doorknobs, hospital furniture – like on handles and bed frames,” Kohli said. “It might even be put to use in heating and air conditioning applications.”

Kohli said ENM devices are quick and easy to fabricate and rely on external, low-powered batteries that operate in the milliwatt range.
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The technology can be used by covering household or industrial items with a copper-silver coating before attaching a battery to it, which then generates reactive oxygenated and chlorinated species.
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The ENM devices were fabricated using a simple two-step process (Fig. 1B). First, the polypropylene control surfaces were immersed in a 0.1 M CuSO4 solution for 1 hour (Fig. 1B and figs. S1 and S2), yielding an average copper concentration of ([Cu(II)]) ≈ 15.7 parts per million (ppm) cm−2 (n = 4) on the surfaces (fig. S3). Then, 80- to 100-nm-thick coating of silver was sputtered on both sides of the Cu-containing surfaces (Fig. 1, G and H). The silver coating is composed of NPs of 29 ± 5 nm (n = 172) (Fig. 1I). A typical ENM device is shown in Fig. 1C. ENM devices were also fabricated on a variety of surfaces, including household air filters, cellulose filter paper, and hand paper towels. A detailed procedure for the fabrication of ENM devices is provided in the Supplementary Materials.
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