title: Multisegmented FeCo/Cu nanowires: electrosynthesis, characterization, and magnetic control of biomolecule desorption.
abstract: In this paper, we report on the synthesis of FeCo/Cu multisegmented nanowires by means of pulse electrodeposition in nanoporous anodic aluminum oxide arrays supported on silicon chips. By adjustment of the electrodeposition conditions, such as the pulse scheme and the electrolyte, alternating segments of Cu and ferromagnetic FeCo alloy can be fabricated. The segments can be built with a wide range of lengths (15-150 nm) and exhibit a close-to-pure composition (Cu or FeCo alloy) as suggested by energy-dispersive X-ray mapping results. The morphology and the crystallographic structure of different nanowire configurations have been assessed thoroughly, concluding that Fe, Co, and Cu form solid solution. Magnetic characterization using vibrating sample magnetometry and magnetic force microscopy reveals that by introduction of nonmagnetic Cu segments within the nanowire architecture, the magnetic easy axis can be modified and the reduced remanence can be tuned to the desired values. The experimental results are in agreement with the provided simulations. Furthermore, the influence of nanowire magnetic architecture on the magnetically triggered protein desorption is evaluated for three types of nanowires: Cu, FeCo, and multisegmented FeCo15nm/Cu15nm. The application of an external magnetic field can be used to enhance the release of proteins on demand. For fully magnetic FeCo nanowires the applied oscillating field increased protein release by 83%, whereas this was found to be 45% for multisegmented FeCo15nm/Cu15nm nanowires. Our work suggests that a combination of arrays of nanowires with different magnetic configurations could be used to generate complex substance concentration gradients or control delivery of multiple drugs and macromolecules.
authors.forename: Berna
authors.initials: B
authors.lastname: Özkale
authors.forename: Naveen
authors.initials: N
authors.lastname: Shamsudhin
authors.forename: George
authors.initials: G
authors.lastname: Chatzipirpiridis
authors.forename: Marcus
authors.initials: M
authors.lastname: Hoop
authors.affiliation: ‡Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zürich, Zürich 8093, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Gramm
authors.forename: Xiangzhong
authors.initials: X
authors.lastname: Chen
authors.affiliation: §Department of Spintronics and Nanoelectronics, Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic.
authors.forename: Xavi
authors.initials: X
authors.lastname: Martí
authors.forename: Jordi
authors.initials: J
authors.lastname: Sort
authors.forename: Eva
authors.initials: E
authors.lastname: Pellicer
authors.forename: Salvador
authors.initials: S
authors.lastname: Pané
mesh_terms: D065966:Absorption, Physicochemical / Q000528:radiation effects; D000327:Adsorption / Q000528:radiation effects; D003035:Cobalt / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D003460:Crystallization / Q000379:methods; D004595:Electroplating / Q000379:methods; D007501:Iron / Q000737:chemistry; D060526:Magnetic Fields; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D053770:Nanowires / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D011485:Protein Binding / Q000528:radiation effects; D011506:Proteins / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D011506:Proteins; D003035:Cobalt; D003300:Copper; D007501:Iron
keywords: magnetically triggered release; multisegmented nanowires; template-assisted electrodeposition; tunable magnetic properties