• A light-activated coating can kill bacteria on surfaces such as phones and laptops
  • It can work in both ambient and extreme light
  • It kills bacteria by producing small amounts of hydrogen peroxide when exposed to light

Laptops and phones are major sources of healthcare-associated infections since they are touched repeatedly during the day. They can act as a spreader for diseases, especially bacterial infections.

Researchers at the University College of London have developed a special, light-activated coating that can help disinfect these surfaces and kill bacteria such as Clostridioides difficile (C. difficile), methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli).

The coating gets activated by light and is successful in killing bacteria, even in low-intensity, ambient light coating (300 Lux) and intense light (3000 Lux). The coating is made of tiny clusters of modified gold embedded in polymer with crystal violet anti-bacterial dye.

“Dyes such as crystal violet are promising candidates for killing bacteria and keeping surfaces sterile as they are widely used to disinfect wounds. When exposed to bright light, they create reactive oxygen species, which in turn kill bacteria by damaging their protective membranes and DNA. This is amplified when they are paired with metals such as silver, gold and zinc oxide," Dr. Gi Byoung Hwang, first author of the study told

Generally, antibacterial coatings only kill bacteria, when exposed to Ultraviolet (UV) light. But, continuous exposure to UV light can impact your health and therefore, it is not practical. This coating can do it varying lights, which makes it something that can be used on smartphone screens as well as laptop keyboards.

The researchers put the coating to test by using bactericides on sample surfaces. The surfaces were populated with 100,000 colony-forming units of bacteria and investigated under different lighting conditions ranging from 200-429 Lux.

In ambient light, the crystal violet coating was ineffective. However, the addition of modified gold made it effective in killing bacteria.

The researchers also found that the coating kills bacteria because it produces small amounts of the disinfectant hydrogen peroxide when exposed to light. It works by chemically attacking the cell membrane and thereby, killing the bacteria.

The gold is key here because it leads to the production of hydrogen peroxide.

Bacteria, as seen under a microscope. PublicDomainPictures/Pixabay