Synthetic vocal cords made from antifreeze chemical

July 15, 2011
Polymer Gel

Polymer gel mimics the vibrations of human vocal cords (credit: MIT/MGH)

Researchers at MIT and Harvard University are developing a synthetic material to revitalize damaged vocal cords.

The researchers are developing a polymer gel that they hope to start testing in a small clinical trial next year. The gel, which mimics key traits of human vocal cords, could help millions of people with voice disorders. They chose polyethylene glycol (PEG) as its starting material, in part because it is already used in many FDA-approved drugs and medical devices.

By altering the structure and linkage of PEG molecules, the researchers were able to control the material’s viscoelasticity. They wanted to make a substance with the same viscoelasticity as human vocal cords. Viscoelasticity is critical to voice production because it allows the vocal cords to vibrate when air is expelled through the lungs.

For use in vocal cords, the researchers created and screened many variations of PEG and selected one with the right viscoelasticity, which they called PEG30. In laboratory tests, they showed that the vibration that results from blowing air on a vocal-fold model of PEG30 is very similar to that seen in human vocal folds. Also, tests showed that PEG30 can restore vibration to stiff, non-vibrating vocal folds such as those seen in human patients suffering from vocal-fold scarring.

If approved for human use, the gel would likely have to be injected at least once every six months, because it eventually breaks down.

Sandeep S. Karajanagi, et al., Assessment of Canine Vocal Fold Function After Injection of a New Biomaterial Designed to Treat Phonatory Mucosal Scarring, Annals of Otology, Rhinology & Laryngology, 2011;120:175-184