Biological applications of multifunctional magnetic nanowires (invited)

Magnetic particles that can be bound to cells and biomolecules have become an important tool for the application of force in biology and biotechnology. Multifunctional magnetic nanowires fabricated by electrochemical deposition in nanoporous templates are a type of magnetic carrier that offers significant potential advantages over commercially available magnetic particles. Recent experimental work aimed at developing these wires for this purpose is reviewed. Results on chemical functionalization of Au and Au/Ni wires and magnetic manipulation of wires in suspension are described. Fluorescence microscopy was used to demonstrate the covalent binding of thiol-terminated porphyrins to Au nanowires, and to optimize functionalization of two-segment gold-nickel nanowires for selectivity and stability of the nanowire-molecule linkages. Magnetic trapping is a technique where single nanowires are captured from fluid suspension using lithographically patterned micromagnets. The influence of an external magnetic field on this process is described. The dynamics of magnetic trapping is shown to be well described by a model based on the interplay of dipolar forces and viscous drag. (C) 2003 American Institute of Physics.