MechSE professor's work featured as Editor's Choice in Science magazine

In a recent Optics Express article, Illinois researchers have shown that second-harmonic generation (SHG) imaging can sensitively differentiate between healthy and injured horse tendon.

“The trick is the combination of SHG microscopy with Fourier analysis,” said Kimani Toussaint, an assistant professor of mechanical science and engineering who collaboratorated on the project with colleagures at the Institute for Genomic Biology and the College of Veterinary Medicine. “The SHG gives us really sharp images of the collagen fibers in the tendon, while spatial Fourier analysis is done on the images to quantify collagen fiber organization such as fiber orientation.”

Tendon inflammation (or tendonitis) can result from overuse or injury and is a major orthopedic condition among athletes, both human and horse. Often imaging of tendonitis involves staining the collagen fibers for contrast enhancement when viewing under a polarized light microscope.

In this study, the researchers compared images taken of normal and injured horse tendon using polarized light microscopy with those taken using SHG microscopy. They found that the latter technique offered several advantages.

“With SHG, we don’t have to stain the specimens, and we get high contrast 3D images unlike polarized light microscopy,” said co-author Raghu Ambekar, an electrical and computer engineering doctoral candidate in Toussaint’s lab. The resulting images are digitized and subsequently analyzed to look for patterns or features that could be of interest. The researchers found that injured tendon had fibers oriented in various directions unlike normal tendons which exhibited highly aligned fibers.

“The point of our study was that these differences are much more pronounced using SHG microscopy than polarized light microscopy," Toussaint added. "Hopefully, in the future this can be useful as some sort of endoscopic tool that doctors can use to better diagnose tendonitis.”

Recently, this work was featured in the biophysics section of the Editor’s Choice column of the prestigious journal Science (volume 330, issue 6011, pg. 1589). The researchers credit a National Science Foundation CAREER award and the American Quarter Horse Foundation for supporting the work.

More about PROBE Photonics Research of Bio/Nano Environments Laboratory.
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Contact: Kimani C. Toussaint, Jr., Department of Mechanical Science and Engineering, 217/244-4088.

If you have any questions about the College of Engineering, or other story ideas, contact Rick Kubetz, editor, Engineering Communications Office, University of Illinois at Urbana-Champaign, 217/244-7716.