Infrared Imaging In Three Dimensions

A new infrared spectroscopy method allows for nondestructive, three-dimensional imaging without labels, contrast agents, or sectioning (Nat. Methods 2013, DOI: 10.1038/nmeth.2596). The technique, synchrotron Fourier transform infrared (FTIR) spectro microtomography, was developed by a group led by Michael C. Martin of Lawrence Berkeley National Laboratory and Carol J. Hirschmugl of the University of Wisconsin, Milwaukee. It combines computed tomography—the same technique that produces 3-D medical X-ray images—with 2-D synchrotron-based FTIR spectroscopy. The end result is a 3-D image that reveals the chemically rich information available from IR spectroscopy. The researchers used the method to show the structures of cell walls in zinnia plants and eastern cottonwood trees on the basis of hydroxyl and hydrocarbon signals. In human hair samples, the team imaged protein filling the cortex and phospholipids in the central medulla. They probed a mouse embryoid body and found heterogeneous lipid distribution, which they hypothesize corresponds to differentiating cells. They also studied a volcanic glass fragment and imaged the water distribution, which could hold clues to how and why the volcano erupted.