If this technology lives up to its promise, it may someday be possible to flood the body with designer molecules that with a flash of light could activate a drug in a precise area to treat something like cancer, destroy the cancer cells at that site, and then be switched off and thus avoid damaging healthy cells, now one of the major drawbacks of various cancer treatments.
This is a long shot, but the technology may eventually help scientists tackle the "holy grail" of neurological surgery.
The human brain is protected by the blood-brain barrier, which blocks entry to the brain of nearly anything that is not normally part of the process. Thus drugs, which could treat an inoperable brain tumor, can't get past the barrier.
But if the drugs could masquerade as a chemical that is friendly to the brain, and then activated once it is inside, and deactivated after it finishes its assignment, many lives could be saved.
And you can make a molecule look like something it isn't just by changing its shape.
"In biology, shape is one of the key factors that dictate the function of a molecule," Branda said. "The chemical that makes caraway seeds smell like caraway seeds is identical to the molecule that makes spearmint smell like spearmint, except they are mirror images of each other. The nose has receptors that are so sensitive they can sense not just the shape of a molecule, but the three-dimensional handedness of the molecule, whether it's left handed or right handed."
So you design a molecule that looks left handed - and thus relatively harmless - and get it to wherever in the body you want it to go, and then hit it with light and change it to right handed so it can kill cancerous cells. Then you turn it off.
Of course, there are still some tough challenges ahead. The Canadian researchers used ultraviolet light to turn their molecules on, but that light is extremely toxic, as anyone who has spent too much time in the sun knows. UV light is probably out.
"So you have to be able to harness light and use light in creative ways that's less damaging," Branda said.
In earlier research, Branda's team added a nano-particle to their molecule, which absorbs infrared light, which is far less harmful to human tissue. The nano-particle acts as an antenna, absorbing the red light, which is then converted internally to ultraviolet or visible light, depending on whether the molecule is to be turned on or off. So the UV light is restricted to the precise area where the molecule is to do its work.
All of this, of course, is still in the realm of basic research. Many labs are working on the same problem, trying to develop ways to use light to control biological functions in a very precise way, turning them on when they are needed, and off when they aren't.
By the way, whatever happened to all those worms? Many survived through multiple replications of the experiment, but in the long run, it proved too toxic. They all eventually died.