Antibiotic switch uses visible light

University of Groningen scientists led by organic chemist Ben Feringa have fitted an antibiotic with a switch that allows them to activate or deactivate the drug using visible light. Earlier versions of the switch were operated with ultraviolet light.

The Feringa group has made a switchable antibiotic before, but that version wasn’t suitable for medical use as the switch was only sensitive to UV light. This is harmful for living cells (it causes sunburn) and will not penetrate very far into the body of a patient. And that is where it needs to work as the purpose of the switch is to activate the antibiotic only where it is needed.

In the new paper, which appeared last month in the Journal of the American Chemical Society, the switch has been modified to respond to infrared light. Laboratory tests with the bacterium Escherichia coli show an 8-fold increase in the effect of the antibiotic after activation. This is a proof of principle that shows it is possible to make drugs with an on/off switch. Such a switch might also be of interest for use in anti-cancer drugs, which are notoriously poisonous and can have severe side effects.