Researchers at the University of Chicago have developed light-activated nanowires that can stimulate neurons to fire when they are exposed to light. The researchers hope that the nanowires could help in understanding complex brain circuitry, and they may also be useful in treating brain disorders.
Optogenetics, which involves genetically modifying neurons so that they are sensitive to a light stimulus, has attracted a lot of attention as a research tool and potential therapeutic approach. However, some researchers have misgivings about optogenetics, as it involves inserting a gene into cells, potentially opening the door to unforeseen effects and possibly permanently altering treated cells.
In an effort to develop an alternative, a research team at the University of Chicago has devised a new modality that can enable light activation of neurons without the need for genetic modification. Their technique involves nanowires that are so small that if they were laid side-by-side, hundreds of them would fit on the edge of a sheet of paper. Although initially designed for use in solar cells, their small size also makes them well suited to interacting with cells.
The nanowires are made from two different kinds of silicon and are covered in a fine coating of gold. Their design means that they release a small electrical current when illuminated. “When the wire is in place and illuminated, the voltage difference between the inside and outside of the cell is slightly reduced. This lowers the barrier for the neuron to fire an electrical signal to its neighboring cells,” said Bozhi Tian, a researcher involved in the study.
The researchers tested their technique using rat neurons grown in a dish and found that by shining a light on the cells they could activate the neurons to fire when the nanowires were present. “The nice thing about it is that both gold and silicon are biologically compatible materials,” said Ramya Parameswaran, first author on the study. “Also, after they’re injected into the body, structures of this size would degrade naturally within a couple of months.”
The nanowires could offer a viable alternative to optogenetics. The scientists are planning to test the nanowires in animals, to see if they can be used to understand the brain’s electrical circuitry and identify new treatments for brain diseases, such as Parkinson’s disease.
Study in Nature Nanotechnology: Photoelectrochemical modulation of neuronal activity with free-standing coaxial silicon nanowires…
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