The nanopore-based sensor probes the nervous system

WASHINGTON, January 10, 2023 — The proteins tau and tubulin are a major cause of many neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. Most of the development of neurodegenerative disease is associated with the accumulation of these proteins in the brain.

Inspired by a doctoral student who wanted to explore the proteins tau and tubulin, Jiali Li, a professor of physics at the University of Arkansas, and her group created a special sensor based on silicon nitride.

in Journal of Applied Physics, from AIP Publishing, Acharjee et al. introduced the device, designed to provide volumetric information on tau and tubulin protein molecules and their states of aggregation at the single-molecule level within their native environment.

To create the sensor, the team explored how the proteins alter the current and voltage flowing through the nanopore system.

“Ohm’s law is the fundamental physics that enables a nanopore device to sense protein molecules,” Lee told me. “A tiny hole — 6 to 30 nanometers across — made in a thin silicon nitride film and supported by a silicon substrate. When placed in a solution with salt ions, applying an electrical voltage causes ions to flow through the hole, or nanopore. This, in turn, generates an open ionic current pores.”

When a charged protein molecule – often thousands of times larger than an ion – is near the nanopore, it is also pushed into the nanopore and blocks the flow of some ions. This causes the open pore current to decrease.

“The amount of current drop produced by the protein molecule is proportional to the size or size and shape of the protein,” he told me. “This means that if protein A binds to protein B, it will cause a current drop proportional to the magnitude of A + B, and aggregated protein A will cause approximately multiple amounts of current drop.”

This allows Li and her group to consider protein binding and assembly within a nanopore device. The amount of time a protein stays in the nanopore is inversely proportional to its charge, which also provides useful information about the protein molecule.

“Our study shows that a silicon nitride nanodevice can measure and aggregate size information of tau and tubulin protein molecules under different biological conditions. This gives us a better understanding of the protein aggregation process, as well as the development of drugs or other therapeutic approaches to treat neurodegenerative diseases.”

Using the solid-state nanopore device, together with other nanotechnology tools, “we plan to systematically study the mechanism of protein aggregation under different biological conditions, such as temperature, pH, and salt concentration,” she says.

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The article “Characterization of Tau and tubulin protein aggregation by solid nanopores method and atomic force microscopy” was written by Mitu C. Acharjee, Haopeng Li, Ryan Rollings, Bo Ma, Steve Tung, and Jiali Li. To appear in the Journal of Applied Physics on January 10, 2023 (DOI: 10.1063/5.0123688). After this date, it can be accessed at https://aip.scitation.org/doi/10.1063/5.0123688.

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Journal of Applied Physics It is an influential international journal that publishes important new experimental and theoretical results in all areas of applied physics. We see https://aip.scitation.org/journal/jap.

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