Both Leroueil's work and the earlier research used model membranes to probe the effects of nanoparticles. Now, the research group is exploring their interactions with living cells.
"Just because we see hole formation in the model system doesn't mean that it really happens in the cell," said Banaszak Holl. But early results of experiments with living cells suggest that the same types of nanoparticles that punch holes in model membranes also damage membranes in living cells and make the membranes more permeable. Hong is now trying to learn more about the biological mechanisms involved. The usual explanation for how polycationic polymers and similar nanoparticles get into cells involves a process called polycation-mediated endocytosis. But Hong's experiments suggest that nanoscale hole formation may be at least as important in allowing materials to travel through membranes.
The work that Banaszak Holl, Hong and Leroueil will discuss is one of several major research programs under way in the U-M Center for Biologic Nanotechnology---a multi-disciplinary group includes researchers from the Medical School, the College of Engineering, and the College of Literature, Science, and the Arts, and focuses on biomedical applications of nanomaterials. Collaborators on this work include James R. Baker, Jr., the Ruth Dow Doan Professor of Biologic Nanotechnology; Bradford Orr, professor of physics and director of the Applied Physics Program; research associate Jennifer Peters and research investigators Anna Bielinska and Istvan Majoros.