After the fluorescent dye is inserted into the bloodstream, doctors can use high-tech imaging devices to view below the surface of a patient’s skin. The dye will glow under spectral imaging technology to identify anything from a burgeoning tumor to damaged blood vessels. Until now, glowing internal dyes have been made mostly from carbon nanotubes or quantum dots. Because these particles remained in the liver and the spleen for days or even months, patients were vulnerable to more internal damage than the diagnostics were worth.
The Stanford team’s new dye solution contains molecular fluorescent particles that emit light within the near-infrared range of light. Technically this range is known as NIR-II, or the second near-infrared window. This specific light range is crucial to the efficacy of the dye because it means the particles produce longer wavelengths that can be viewed through many layers of tissue and skin without scattering. Stanford’s new dye enables imaging so accurate that real-time video capture is now a possibility.
“The difficulty is how to make a dye that is both fluorescent in the infrared and water soluble,” said Alex Antaris, a graduate student on the Stanford team. The most important achievement in this new fluorescent dye is its soluble quality, which allows it to be excreted from the body within 24 hours. That tacks on a whole new level of safety to the initial benefit of vastly more accurate imaging below the skin. The fluorescent dye could spark a major step forward in medical imaging, from basic diagnostics to imaging-guided surgery.
