Chemical engineers from the Massachusetts Institute of Technology (Cambridge, MA) have developed arrays of carbon nanotube sensors that detect single protein molecules as they are secreted from cells, or even an individual cell.

Scientists can use the sensors to track viral infection, monitor cells’ manufacturing of useful proteins, and reveal food contamination.

“We hope to use sensor arrays like this to look for the ‘needle in a haystack,’” said 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.

Strano’s lab has previously developed sensors that detect many types of molecules, all based on modifications of carbon nanotubes — hollow, nanometer-thick cylinders made of carbon that naturally fluoresce when exposed to laser light.

With the new MIT development, the researchers used chains of DNA called aptamers to coat the carbon nanotubes. The molecules bind with a specific signaling proteins and change the nanotubes' fluorescence in a measurable way.

"This platform will open a new path to detect trace amounts of proteins secreted by microorganisms,” said postdoc researcher Juyao Dong. “It will advance biological research [on] the generation of signal molecules, as well as the biopharmaceutical industry’s [efforts to monitor] microorganism health and product quality.”

In the pharmaceutical industry, the sensors could additionally 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.