Special Condensed Matter Seminar

Friday May 12 at 4:00, PAB 2-434

New Probes of Soft Matter and Sub-Cellular Force Transduction using Magnetic Nanowires

Professor Daniel H. Reich

Department of Physics and Astronomy

Johns Hopkins University, Baltimore, MD 21218

Magnetic microparticles and nanoparticles are playing an ever-increasingly important role in the study of soft matter, whether as microrheological probes of complex fluids, or for biophysical studies of living cells’ responses to applied forces and stress. Recent advances in magnetic nanostructure engineering are now enabling the design and fabrication of magnetic nanoparticles that can be tailored for a variety of specific applications. For example, we are developing new soft matter probes using asymmetric, multisegment magnetic nanowires. These nanoparticles’ multisegment architecture, high aspect ratio, and the ability to vary the aspect ratio and juxtaposition of dissimilar segments allows them to be given a wide range of magnetic, optical, and other physical properties. In addition, differences in the surface chemistry between segments can be exploited to selectively bind different ligands to those segments, giving the particles spatially resolved surface functionality. I will describe recent experiments exploiting these probe particles including (i) characterization of the elastic energy of a nematic liquid crystal due an elongated inclusion as a function of its orientation and the dynamic response of the nanowire to this interaction, and (ii) recent results on the non-local contractile response of cells to local forces, using magnetic nanowire-based soft actuator microarrays.

Host: Giovanni Zocchi ; zocchi@physics.ucla.edu