Laser particles could provide sharper images of tissues

A new imaging technique developed by scientists at MIT, Harvard University, and Massachusetts General Hospital (MGH) aims to illuminate cellular structures in deep tissue and other dense and opaque materials. Their method uses tiny particles embedded in the material, that give off laser light.

The team synthesized these “laser particles” in the shape of tiny chopsticks, each measuring a small fraction of a human hair’s width. The particles are made from lead iodide perovskite — a material that is also used in solar panels, and that efficiently absorbs and traps light. When the researchers shine a laser beam at the particles, the particles light up, giving off normal, diffuse fluorescent light. But if they tune the incoming laser’s power to a certain “lasing threshold,” the particles will instantly generate laser light.

The researchers, led by HST MEMP student Sangyeon (Frederick) Cho, demonstrated they were able to stimulate the particles to emit laser light, creating images at a resolution six times higher than that of current fluorescence-based microscopes.

“That means that if a fluorescence microscope’s resolution is set at 2 micrometers, our technique can have 300-nanometer resolution — about a sixfold improvement over regular microscopes,” Cho says. “The idea is very simple but very powerful and can be useful in many different imaging applications.”

Cho and his colleagues have published their results in the journal Physical Review Letters. His co-authors include Seok Hyun Yun, a professor at Harvard; Nicola Martino, a research fellow at Harvard and MGH’s Wellman Center for Photomedicine; and Matjaž Humar, a researcher at the Jozef Stefan Institute. The research was done as part of the Harvard-MIT Division of Health Sciences and Technology.

Tuesday, November 15, 2016