Tracking Nanoparticle Growth

A new technique enables scientists to follow nanoparticle growth with a “label”—a metallic seed that is distinguishable from the rest of the nanoparticle via electron microscopy. Using the method, Chad A. Mirkin of Northwestern University and coworkers have mapped how metallic nanoparticles change shape as they grow (Science, DOI: 10.1126/science.1225653). Knowing how nanoparticles evolve into certain shapes could help scientists better control the materials’ electronic and catalytic properties, the team says. “We have done for nanoparticle mechanistic work what the isotopic-labeling folks and fluorescent-labeling folks have done for synthetic chemistry and biology, respectively,” Mirkin says. Oftentimes, he adds, “nanoparticles are made in a black-box type of operation.” A graduate student might be an expert at making a particular particle shape under a certain set of conditions, he explains, but typically little is known about why the shape forms. Such syntheses can be quite useful, Mirkin adds, but it ...