Biological applications of multifunctional magnetic nanowires (invited)

TLDR

Magnetic particles that can be bound to cells and biomolecules are an important tool for applying force in biology and biotechnology, and multifunctional magnetic nanowires fabricated by electrochemical deposition in nanoporous templates offer significant advantages over commercially available magnetic particles. The review focuses on recent experimental work developing multifunctional magnetic nanowires for force application and examines how an external magnetic field influences the trapping process. Fluorescence microscopy demonstrates covalent binding of thiol‑terminated porphyrins to Au nanowires and optimizes functionalization of two‑segment gold–nickel nanowires, while magnetic trapping captures single nanowires from suspension using lithographically patterned micromagnets and is affected by external magnetic fields. Chemical functionalization of Au and Au/Ni nanowires and magnetic manipulation in suspension are reported, and the dynamics of magnetic trapping are well described by a model based on dipolar forces and viscous drag.

Abstract

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.