A Rice University lab’s project to make better fluorescent tags has turned into a method to kill tumors.
A Rice University lab’s project to make better fluorescent tags has turned into a method to kill tumors.
Switching one atom in the tag does the trick. Rice chemist Han Xiao and his colleagues found that replacing a single oxygen atom with a sulfur atom in a common fluorophore turns it into a photosensitizing molecule. When exposed to light, the molecule generated reactive oxygen species (ROS) that destroyed breast cancer cells in the lab.
The study led by co-lead authors Juan Tang and Lushun Wang, both Rice postdoctoral researchers, appears in the Royal Society of Chemistry flagship journal Chemical Science.
This method of photodynamic therapy is already in use, as light-triggered molecules are known to generate cytotoxic ROS. Most current photosensitizers require the incorporation of heavy atoms, but they are difficult and costly to synthesize and remain toxic in the dark, potentially damaging healthy cells, Xiao said.
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Illustration: The design of thio-based photosensitizers, at left, by Rice University chemists shows promise for photodynamic cancer therapy, among other applications. One thiocarbonyl substitution — trading an oxygen atom for a sulfur atom — of a variety of fluorophores can dramatically enhance their ability to generate reactive oxygen species that kill cancer cells. At right, images of multicellular tumor spheroids treated with photosensitizers and light (in the bottom row) show how the compounds, when excited by light, damage the cells. Illustration courtesy of the Xiao Lab
