In recent years, using fluorescent, glowing dyes to get an inside look at the human body has become commonplace. For example, injecting a dye into a patient's bloodstream and subsequently shining a light on their eye will lead to vasodilation and provide a glowing map of their retina using computer software. However, many of these dyes have safety concerns and can linger in the body, limiting their potential — until now.

Scientists from Stanford University created molecular fluorescent dyes that create light that falls near the infrared range, an area called the second near-infrared window, which means they have long wavelengths that allow them to easily escape from bodily tissues with minimal scattering.

The new dye can be excreted through urine within a 24-hour time period and will lead to increased safety and better quality images in the realm of human health care.

"The difficulty is how to make a dye that is both fluorescent in the infrared and water soluble," said Alex Antaris, first author of the paper, in a press release. "A lot of dyes can glow, but are not dissolvable in water, so we can't have them flowing in human blood. Making a dye that is both is really the difficulty. We struggled for about three years or so and finally we succeeded."

The new form of imaging created by the study can be used for many areas of health care, in particular as a surgical guide due to its ability to capture real-time videos, which is a huge improvement over tomographic imaging techniques that can take anywhere from minutes to hours to complete just one scan.

"This could enable clinical use of fluorescence imaging to reach unprecedented depth for diagnostics or imaging guided surgery," said Hongjie Dai, who headed the research.

The findings were published in the Nov. 23 issue of Nature Materials.