Chromatographic Method Purifies Complex Magnetic Nanostructures

A magnet-assisted chromatographic method may make it easier to purify certain complex nanoparticles. Such nanostructures—in which tiny magnetic particles are stuck to other particles—are under investigation for medical, catalytic, and diagnostic uses. But many of the reactions researchers rely on to make the multipart particles are complex and can result in mixtures of products. Jacob S. Beveridge, a graduate student in Mary Elizabeth Williams’ lab at Penn State University, described his team’s efforts to show that differential magnetic catch and release, a chromatographic method the researchers developed a few years ago, can be used to separate and purify such complex mixtures of products. The work, which will soon appear in Angewandte Chemie, was performed in collaboration with Penn State chemist Raymond E. Schaak. Beveridge used the method to purify nanoparticles consisting of a magnetic iron oxide core surrounded by three gold nanoparticles. Such particles might serve a dual purpose for medical applications: The gold could anchor drugs and the iron oxide could function as a contrast agent for magnetic resonance imaging. For such a medical application, “it would be unacceptable to have a mixture of particles with a mixture of functions,” Williams told C&EN.