Magnetic Manipulation and Optical Imaging of an Active Plasmonic Single-Particle Fe-Au Nanorod

Yong Zhang, Univ. Coll Dublin
Manuel DaSilva, Birck Nanotechnology Center, Purdue University
Brian Ashall, Univ. Coll Dublin
Gillian Doyle, Univ. Coll Dublin
Dominic Zerulla, Univ. Coll Dublin
Timothy D. Sands, Birck Nanotechnology Center, Purdue University
Gil U. Lee, Univ. Coll Dublin

Date of this Version



Langmuir, 2011, 27 (24), pp 15292–15298


Superparamagnetic microbeads play an important role in a number of scientific and biotechnology applications including single-molecule force measurements, affinity separation, and in vivo and in vitro diagnostics. Magneto-optically active nanorods composed of single-crystalline Au and polycrystalline Fe segments were synthesized with diameters of 60 or 295 nm using templated electro-deposition. The Fe section was magnetically soft and had a saturation magnetization of approximately 200 emu/g, resulting in a 10-fold increase in magnetization relative to that iron oxide nanoparticles. The strong plasmonic response of the Au segment of the rod in both the longitudinal and transverse directions made it possible to detect the orientation of a single rod in a polarized light microscope with nanometer resolution. These nanorods provide significantly improved physical properties over iron oxide superparamagnetic beads, making it possible to simultaneously manipulate and monitor the orientation of biomolecules with well-defined forces at the nanometer scale.


Nanoscience and Nanotechnology