Magnetic Nanoparticles for Biotechnology: Current Uses and New Approaches Daniel Reich Department of Physics and Astronomy Johns Hopkins University Small magnetic particles that can be bound to cells and biomolecules have become important tools for force transduction in microbiology, biophysics, and biotechnology. As this field of biomagnetics expands, it will become increasingly important to develop new nano-engineered magnetic particles that can perform a variety of functions beyond the application of force. I will provide an overview of some current trends and applications of magnetic particles in biology, and will discuss our recent work on multifunctional magnetic nanowires. The architecture of these multi-segmented wires allows for a wide range of magnetic properties through control of the size, shape, composition and juxtaposition of the segments. In addition, the nanowires can be given multiple chemical specificity through the use of ligands that bind selectively to the different segments. Such nanowires can potentially be functionalized to carry out multiple tasks in a biological environment. Experiments will be described that illustrate the multifunctional properties of the nanowires, and demonstrate their use for cell manipulation and other potential applications.