Microscope pinpoints single molecules

IOWA STATE (US) — A new microscope will allow scientists to study biological molecules one at a time.

Cells have surface proteins, called cadherins, that help them stick together. Different kinds of cells have different kinds of cadherins.

The typical tools for observing and measuring those proteins focus on tens of thousands of them at a time—providing data on the average molecule in a sample, but not on a single molecule.

“These fields are so technologically driven, you have to invent new stuff to discover new things,” says Sanjeevi Sivasankar, assistant professor of physics and astronomy at Iowa State University.

Sivasankar combined two single-molecule technologies that had been used separately: atomic force microscope technology that manipulates molecules and measures forces; and fluorescence resonance energy transfer technology that observes single molecules at very high resolution.

Using one or the other technology is like “having hands but no eyes or eyes but no hands,” Sivasankar says. “We can combine these two technologies into one instrument.”

This type of instrument could advance studies in biomedical research, drug discovery, cancer diagnostics, and bio-sensing applications, Sivansankar says.

The new instrument is being used in advancing studies of cadherins and DNA and also in the study of semiconducting nanocrystals.

Sivasankar said the immediate goal is to transform the microscope from its bulky, prototype stage to an instrument that’s novel, compact, easy to use, and can be manufactured at a competitive price.

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