Researchers design sensors that can detect single protein molecules

Researchers design sensors that can detect single protein molecules

Researchers at MIT are currently putting carbon nanotubes to use in medicine and chemical engineering. According to a new paper published in the journal Nature Nanotechnology, MIT engineers have modified carbon nanotubes to create instruments that are able to detect a single protein molecule when it is secreted by a cell.

When exposed to laser light, the nanometer-thick carbon nanotubes glow, but in order to turn them into sensors, the researchers had to first coat them with chains of DNA called aptamers that can bind to a specific target. When this occurs, the nanotubes’ fluorescence changes in a measurable way.

These sensors could help scientists with any application that requires detecting very small amounts of proteins, like tracking viral infection, monitoring cells’ manufacturing of useful proteins, or revealing food contamination.

“We hope to use sensor arrays like this to look for the ‘needle in a haystack,’” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “These arrays represent the most sensitive molecular sensing platforms that we have available to us technologically. You can functionalize them so you can see the stochastic fluctuations of single molecules binding to them.”

To monitor protein production of single cells, the researchers set up an array of the sensors on a microscope slide. When a single bacterial, human, or yeast cell is placed on the array, the sensors can detect whenever the cell secretes a molecule of the target protein.

“Nanosensor arrays like this have no detection limit,” Strano says. “They can see down to single molecules.”

In the pharmaceutical realm, these sensors could be used to test cells engineered to help treat disease. Many researchers are now working on an approach where doctors would remove a patient’s own cells, engineer them to express a therapeutic protein, and place them back in the patient.

Strano says researchers could also use the arrays to study viral infection, neurotransmitter function, and a phenomenon called quorum sensing – the process by which bacteria colonies communicate.

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