A new microscope developed by US researchers can complete 3-D measurements of single biological molecules with unprecedented accuracy and precision.

Blending optical and atomic force microscope technologies, researchers from technologies, Iowa State University and Ames Laboratory have found a way to complete 3-D measurements of single molecules. Previous research efforts only allow researchers to measure single molecules on the x and y axes of a 2-D plane, but this represents a new stage for nanotechnology.

Sanjeevi Sivasankar, an Iowa State assistant professor of physics and astronomy and an associate of the US Department of Energy’s Ames Laboratory said: ”This is a completely new type of measurement that can be used to determine the z position of molecules.”

Details of the new technology have been published in the Journal Nano Letters, with lead author professor Sivasankar saying they had two objects when commencing their research: to learn how biological cells adhere to each other and to develop new tools to study those cells.

It was for this reason that the new microscope technology – called standing wave axial nanometry (SWAN) – was developed. It works by attaching a commercial atomic force microscope to a single molecule fluorescence microscope. Positioning the tip of the atomic force microscope over a focused laser beam, the team managed to create a standing wave pattern.

A molecule which can emit light is placed within the standing wave, and the tip of the atomic force microscope moves up and down. The fluorescence emitted by the molecule then fluctuates in a way that corresponds to its distance from the surface. That distance can be compared to a marker on the surface and measured.

“We can detect the height of the molecule with nanometer accuracy and precision,” Sivasankar said.

“We hope to use this technology to move that research forward, and in doing that, we’ll continue to invent new technologies.”