Nanowires record neuron activity
Colourised SEM image of a neuron (orange) interfaced with the nanowire array.
Researchers from the University of California San Diego and colleagues have developed nanowires that record the electrical activity of neurons in fine detail.
The device consists of an array of silicon nanowires densely packed onto a small chip, patterned with silica-coated nickel electrode leads.
The nanowires probe cells without causing damage and can measure small potential changes that are a a few millivolts in magnitude.
The device can also isolate the electrical signal measured by each individual nanowire.
Colorised SEM image of the nanowire array. [Integrated Electronics and Biointerfaces Laboratory, UC San Diego]
Professor Shadi Dayeh from the UC San Diego Jacobs School of Engineering and colleagues used the nanowires to record the electrical activity of neurons that were isolated from mice and derived from human induced pluripotent stem cells.
These neurons survived and continued functioning for at least six weeks while interfaced with the nanowire array in vitro.
“We’re developing tools that will allow us to dig deeper into the science of how the brain works,” says Dayeh.
“We envision that this nanowire technology could be used on stem-cell-derived brain models to identify the most effective drugs for neurological diseases,” adds Dayeh's colleague, Anne Bang, director of cell biology at the Conrad Prebys Center for Chemical Genomics, Sanford Burnham Medical Research Institute.
Researchers can currently uncover details about a neuron's activity by measuring ion channel currents and changes in its intracellular potential.
But while the state-of-the-art measurement technique is sensitive to small potential changes and provides readings with high signal-to-noise ratios, it can break the cell membrane and eventually kill the cell.
What's more, the method can only analyse only one cell at a time, making it impractical for studying large networks of neurons, which are how they are naturally arranged in the body.
“Existing high sensitivity measurement techniques are not scalable to 2D and 3D tissue-like structures cultured in vitro,” highlights Dayeh. “But the development of a nanoscale technology that can measure rapid and minute potential changes in neuronal cellular networks could accelerate drug development for diseases of the central and peripheral nervous systems.”
Dayeh reckons the new device could one day serve as a platform to screen drugs for neurological diseases and could enable researchers to better understand how single cells communicate in large neuronal networks.
As the researcher explains, the technology needs further optimisation for brain-on-chip drug screening.
His team is also working to extend the application of the technology to heart-on-chip drug screening for cardiac diseases and in vivo brain mapping, which is still several years away due to significant technological and biological challenges that the researchers need to overcome.
“Our ultimate goal is to translate this technology to a device that can be implanted in the brain,” he says.
Research is published in Nano Letters.