Researchers at Northwestern University, Evanston, Illinois, USA, have developed a virus catcher of sorts—that is, a sticky and absorbent surface coating that traps droplets and aerosols (microdroplets) that land on the coating. Most often, fine droplets bounce off surfaces and remain airborne. Reporting in the journal Chem, the researchers found that a polyelectrolyte polymer—namely poly(acrylamide-co-diallyldimethylammonium chloride), a transparent film-forming material commonly used in cosmetics and other personal-care products—absorbed water-based droplets. The significance of this trapping coating is that it could remove infectious respiratory droplets from indoor air, which would be a potentially less expensive means of removal compared to upgrading a ventilation system. Note, however, that the researchers used non-infectious droplets for testing and not human respiratory droplets. See also: Aerosol; Infectious disease; Polymer; Virus

The trapping polymer can be coated onto plastic, glass, wood, metal, concrete, and textile, such as those found in the office shown here. (Credit: PhotoByToR/Shutterstock)

The polyelectrolyte polymer can be coated onto, and cleaned off of, most indoor surfaces without damaging the underlying material. In addition, the coating is transparent, even after repeated droplet absorption. To optimize the coating, the researchers added a non-ionic, plant-based surfactant (alkyl polyglycoside) to improve coating ability on different surfaces and surface textures, as well as copper ions (Cu²⁺) to act as disinfection agents. While further work is needed to prove that the coating works in real-life situations, if successful, the coating could become a useful means for reducing the spread of infectious droplets, such as those responsible for COVID-19. See also: Copper; Coronavirus; Glycoside; Surfactant