Published July 24, 2014
University at Buffalo researchers are part of an international team developing a novel imaging technique with nanoparticles suspended in liquid to provide an unparalleled, noninvasive, real-time view of the small intestine.
The advancement could help doctors better identify, understand and treat a variety of gastrointestinal ailments.
“Conventional imaging methods show the organ and blockages, but our method allows you to see how the small intestine operates in real time,” says Jonathan F. Lovell, PhD, assistant professor of biomedical engineering and corresponding author of a study describing the technique.
“Better imaging will improve our understanding of gastrointestinal diseases and allow physicians to more effectively care for people who suffer from them.”
The multidisciplinary team devised nanojuice by creating novel ‘nanonap’ nanoparticles with colorful dye molecules that can disperse in liquid and move safely through the intestine.
After feeding the nanojuice to mice, the researchers used photoacoustic tomography — harmless pulsed laser lights — to generate pressure waves. Measuring these waves successfully produced a high-resolution, nuanced, real-time view of the small intestine.
Key to their success was the development of a family of nanoparticles that have three important qualities: they can withstand the harsh conditions of the stomach and intestine, avoid systemic absorption and provide good optical contrast for photoacoustic imaging, Lovell explains.
The researchers overcame a major obstacle by exploiting small-molecule naphthalocyanines — a family of dyes — to generate purified frozen micelles, dubbed ‘nanonaps,’ that disperse in liquid.
Typically, naphthalocyanines absorb large portions of light in the near-infrared spectrum — the ideal range for biological contrast agents. But because they don’t disperse in liquid, they can be absorbed from the intestine into the bloodstream and, therefore, are unsuitable for use in humans.
Current diagnostic tools are limited in their ability to visualize problems in the roughly 23-foot, human small intestine.
Various gastrointestinal conditions may be linked to dysfunctions in peristalsis, the muscle contractions that propel food through this long, folded tube. These conditions include irritable bowel syndrome, celiac disease and Crohn’s disease, as well as side effects of thyroid disorders, diabetes and Parkinson’s disease.
Yet, no imaging tool is highly effective at providing real-time views of peristalsis.
In addition, X-rays have safety issues; the small intestine is difficult to access with MRI, and ultrasound does not provide adequate contrast.
Methods using nanojuice hold promise for overcoming these limitations.
The researchers plan to continue to refine their nanojuice technique for human trials. They also will test the technique’s ability to observe other parts of the gastrointestinal tract in action.
The paper, “Noninvasive Multimodal Functional Imaging of the Intestine With Frozen Micellar Naphthalocyanines,” has been published in Nature Nanotechnology.
Additional authors are from:
The research was funded by the National Institutes of Health; the U.S. Department of Defense; and the Korean Ministry of Science Information and Communications Technology (ICT) and Future Planning.