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

Abstract

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 electrodeposition. 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.

Bio‐Nano‐Magnetic Materials for Localized Mechanochemical Stimulation of Cell Growth and Death

“…Cylindrical particles, termed nanowires or nanorods, have recently been employed in MTW. [9b,44] Templated synthesis using a nanoporous membrane enables the sequential deposition of different metals [44c] or alloys [45] into a single structure, which permits the localized functionalization of the rod. [9b,46] As such, the shape is not only used to control the magnetic anisotropy.…”

In vitro study of the interaction of heregulin-functionalized magnetic–optical nanorods with MCF7 and MDA-MB-231 cells

“…We have recently described the synthesis of Fe-Au nanorods that have high saturation magnetization, low remanence, uniform size and strong 10 plasmonic activity. 14,35 In this study, we targeted specific cancer cell receptors using large (Ø = 200 nm) magnetic nanorods with heregulin-functionalized Au tips. Nanorods functionalized with heregulin using a PEG monolayer selectively bound to the MCF7 target cells that have high levels of ErbB2/3 but did not enter the cells.…”

“…14 chromium oxide at 20 V and 60°C for 45 sec. This polished piece of aluminium was anodized in 0.42 M oxalic acid at 40 V and 0.9°C for 11 hours.…”

“…The synthesis of segmented metal nanorods was based on the method developed described previously. 14 Briefly, an Au layer (ca. 200 nm) was sputtered on one side of the PAA template to serve as a working electrode in an electrochemical setup.…”

“…For example, the enhanced permeability and retention effect (EPR) has been used to target cancers with nanoparticles based on particle size. [12][13][14] Ideally, nanoparticles' interaction with culture cells in vitro could be rapidly screened to determine the mechanism of particle-cell interaction before testing in animal models. In this article we present the results of a study of the interaction of Fe-Au nanorods ~150-200 nm in diameter composed of 45 segments of defined length with cultured cells using an optical microscope capable of tracking individual rods.…”