Painless biopsies with smart lasers

MICHIGAN STATE (US) — Using laser microscopes that deploy rapid, ultra-short pulses to identify molecules, doctors may soon have the tools to perform painless skin cancer biopsies.

To test for skin cancer, patients today must endure doctors cutting away a sliver of skin and anxiously await the lab results.

“Smart lasers allow us to selectively excite compounds—even ones with small spectroscopic differences,” says Marcos Dantus, a chemistry professor at Michigan State University. “We can shape the pulse of the lasers, excite one compound or another based on their vibrational signatures, and this gives us excellent contrast.”

Dantus and co-author Sunney Xie of Harvard University report their findings in the journal Nature Photonics.

In the past, researchers could approach this level of contrast by introducing fluorescent compounds. With the breakthrough using stimulated Raman scattering microscopy, fluorescent markers are unnecessary.

“Label-free molecular imaging has been the holy grail in medicine,” Dantus says. “SRS imaging gives greater specificity and the ability to map a particular chemical species in the presence of an interfering species, such as cholesterol in the presence of lipids.”

Additional potential applications include allowing researchers to closely examine how compounds penetrate skin and hair. Smart lasers also can better identify how drugs penetrate tissue and how drugs and tissue interact, thus mitigating the chances of potential side effects and helping reduce the time required to bring new drugs to market.

Dantus also is using smart laser imaging technology to detect traces of hazardous substances from a distance.

“The ability to image with molecular specificity and sensitivity opens a number of applications in medicine as well as in homeland security,” he says.

The work is funded in part by the National Science Foundation.

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