Stuffed between the stomach and the large intestine, the small intestine is a 23-foot digestive wonder. But when there’s trouble brewing down there, doctors can have a tough time seeing precisely what’s going on because typical medical imaging techniques can’t detect the small movements of muscles propelling food through the turning and twisting organ. A team led by Jonathan F. Lovell of the University at Buffalo, SUNY; Weibo Cai of the University of Wisconsin, Madison; and Chulhong Kim of South Korea’s Pohang University of Science & Technology has come up with a way to let doctors study the small intestine in action. The researchers developed a family of nanoparticles that can be used in photoacoustic tomography, a technique in which the particles respond to laser light by generating pressure waves that can be detected with ultrasound (Nat. Nanotechnol. 2014, DOI: 10.1038/nnano.2014.130). The nanoparticles are micelles made from a biocompatible surfactant and naphthalocyanine dye that can withstand the harsh conditions of the stomach and intestines, avoid systemic absorption, and provide good optical contrast for photoacoustic imaging. When fed to mice, the micelles proved to be effective and nontoxic imaging agents.