Probing Sub-Cellular Force Transduction and Soft Matter using Magnetic Nanowires

Tuesday, February 22, 2011 – 3:15pm
Reiss 502
Daniel Reich
Johns Hopkins University

Magnetic microparticles and nanoparticles are playing an ever-increasingly important role in the study of soft matter, whether as 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 biological and 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 applications of high-moment magnetic nanowires in biological physics experiments that probe the non-local contractile response of cells to local forces, using magnetic nanowire-based soft actuator microarrays, and experiments on nematic liquid crystals wherein the ability to tune the interactions of these anisotropic colloids with the nematic order parameter enables the generation of novel elastic forces on the particles and the observation of dynamic lift.

Host: Daniel Blair
Discussion Leader: Daniel Blair