How can light kill viruses?
To stave off infection, there are some things you probably know you should do: wash your hands, be careful when you sneeze, gets lots of sleep, don't rub your eyes (especially after touching your nose), eat lots of fruits and vegetables. After all, a cold virus can survive on someone's hand for a couple of hours or for several days on some materials.
Even those hand sanitizers that many people use don't kill everything. And once they're in the body, viruses are quite tough to kill -- antibiotics are powerless against them and vaccines for influenza and some other viruses must be changed every year to adapt to new strains. Fortunately our immune systems can fight off many viruses, but some, like Ebola or even influenza, can be deadly. It may then surprise you to learn that something viruses are exposed to all the time -- visible light -- can be used to kill them.
A study by Kong-Thon Tsen of Arizona State University along with researchers at Johns Hopkins University shows how strong blasts of visible light from a low-power laser can kill viruses. The laser technique appears to be more successful than other methods at killing viruses, while also posing less harm to healthy tissue.
In their study, the researchers blasted a virus with a quick pulse of purple laser light. The laser, which only shines for 100 femtoseconds (a femtosecond is one millionth of a billionth of a second), causes the virus's capsid (its outer shell) to vibrate and become damaged. Essentially, the virus becomes "deactivated" while the area around the virus remains unharmed. The treatment doesn't cause viruses to mutate either, which is a problem in other virus treatments and can lead to viral resistance.
While the treatment is still in testing, it presents an array of potential applications. Serious diseases like HIV/AIDS and hepatitis could be blasted with laser light. Scientists could cleanse blood samples of viruses and other pathogens, making them safer to handle. Scientists could also combine the laser therapy with current blood dialysis treatments. In that case, blood would be cycled out of a patient's body, lasers could eliminate any pathogens in the blood and the blood would be cycled back in.
Future tests will focus on possible side effects, though as of yet, none have been discovered.
Doctors are limited in the ways they can fight viruses, which is why studies like this one are so exciting. On the next page, we'll look at more ways in which scientists try to fight viruses or stop their spread altogether. Several of them use light, whether to kill viruses or as an activating agent.