The growing field of optogenetics involves the use of light to control neural activity, a process that has wide implications for treating genetic diseases such as macular degeneration. But up until now, the therapy has required the use of genetically modified neurons, limiting its effectiveness in the human population.
Researchers at the University of Chicago and the University of Illinois at Chicago have found a way to affect normal neurons with heat generated from infrared light, according to a paper published in the journal Neuron. Using gold nanoparticles targeted to specially treated neurons, the scientists were able to focus the heat to a very specific subset of cells.
Normally, the cells need to have been modified with a light-responsive protein--one derived from algae--that allows them to become stimulated by the light alone. But by bringing gold nanoparticles, and thus highly targeted heat, into the equation, the cells wouldn't need to have been modified genetically at all.
The process does require some modification of a different sort, however, to get the nanoparticles to stay in place. So the researchers coupled the gold particles to a synthetic molecule based on a scorpion neurotoxin, Ts1, to get them to stick to sodium channels on the neurons. They didn't find any harmful effects in early tests, but the researchers note that toxicity is still possible.
"This is effectively optogenetics without genetics," lead author Francisco Bezanilla said in a statement. "Many optogenetic experimental designs can now be applied to completely normal tissues or animals, greatly extending the scope of these research tools and possibly allowing for new therapies involving neuronal photostimulation."