Now, it seems that light could also have cancer-fighting properties. Not just any light, of course. We are talking about high-energy light.
This type of light, such as ultraviolet laser light, can form free radicals with the unique ability to attack cancer tissue. There is one problem though.
Ultraviolet light doesn’t travel far enough into tissues to have an effect close to the tumor site. This limitation can be bypassed with photo up-conversion.
However, up-converted materials have either low efficiency or are based on toxic materials. There is one solution that has been out of reach for scientists so far: nontoxic silicon.
Why? Because until now no one has been able to demonstrate that silicon nanocrystals can up-convert photons. That may all change soon.
A team of researchers led by UC Riverside materials science doctoral student Pan Xia analyzed the surface chemistry of silicon nanocrystals to learn how to attach ligands. Ligands bind molecules to the nanoparticles that can transfer the energy from the nanocrystals to molecules.
The team then discovered that silicon nanocrystals equipped with these ligands could transfer the energy to the triplet state of surrounding molecules. This process is called triplet-triplet fusion.
This type of fusion converts the low-energy excitation to a high energy one. “We functionalized silicon nanocrystals with anthracene. Then we exited the silicon nanocrystals and found that the energy was efficiently transferred from the nanocrystal, through the anthracene molecules, to the diphenylanthracene in solution,” said Xia.
“It means we got higher-energy light.”
The discovery could be used to develop minimally invasive cancer treatments. But that's not all, it also has applications in technologies for solar-energy conversion, quantum information, and near-infrared driven photocatalysis.
The study was published in Nature Chemistry.