Researchers refine a powerful laser microscope for biomedical use

LAWRENCE — Researchers from the University of Kansas are building a smaller, cheaper and more flexible fiber-laser microscope that could revolutionize biomedical and clinical work.

Coherent anti-Stokes Raman Spectroscopy already is a proven and powerful technology for peering into cells to observe lipids, proteins and DNA. But the lasers involved in CARS microscopy are complex and pricey, available only to top research institutions with deep pockets.

The KU project, headed by Carey Johnson, professor of chemistry, aims to simplify the tool and make using it faster and more economical. The goal is to bring the technology down in cost, and within reach of medical clinics and biomedical researchers.

“CARS has been around for a long time, but it’s been developed based on $300,000 laser systems that take up large optical tables,” Johnson said. “It’s not a very usable method of microscopy for everyday clinical use — it requires a very specialized lab and a system that’s not portable.”

By contrast, the simplified CARS system that Johnson is developing with Rongqing Hui, a fiber-optic expert and KU professor of electrical engineering and computer science, is based upon a single fiber laser and could fit inside a shoebox.

“This laser source would be much smaller, and much less expensive than the kinds of laser sources being used now for this kind of laser microscopy,” said Johnson. “We hope to make it much more accessible.”

Because every molecule vibrates at a unique frequency, CARS can identify unique molecules by reading those frequencies with laser beams.

“We pass two different wavelengths of light straight through the sample, and the CARS process creates a third wavelength, where the strength of that signal depends on the vibrations of the molecule,” Johnson said. “If the difference between frequencies of the two beams that we send into the sample match its vibrational frequency, that amplifies the signal, and we look for that amplification in the output beam.”

The collaboration could usher in low-cost CARS microscopy and put the powerful tool in the hands of more clinicians and researchers.

“It’s important because we can look at the cells as they are,” said Johnson. “We don’t have to treat them with a dye, or a stain or some kind of label that would make them fluoresce. Currently, one has to go through extra steps to have cells genetically make something that fluoresces. This method avoids that.”

Funded by $156,000 from the National Institutes of Health, the instrument-making project will take three years and should result in a prototype fiber-optic laser microscope by 2014.