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Nat Nanotechnol. 2017 Mar;12(3):228-232. doi: 10.1038/nnano.2016.235. Epub 2016 Nov 7.

High-strength magnetically switchable plasmonic nanorods assembled from a binary nanocrystal mixture.

Author information

1
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
2
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
3
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
4
The Nature Conservancy, Arlington, Virginia 22203, USA.
5
Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
6
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
7
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
8
Materials Department, University of California Santa Barbara, Santa Barbara, California 93106, USA.

Abstract

Next-generation 'smart' nanoparticle systems should be precisely engineered in size, shape and composition to introduce multiple functionalities, unattainable from a single material. Bottom-up chemical methods are prized for the synthesis of crystalline nanoparticles, that is, nanocrystals, with size- and shape-dependent physical properties, but they are less successful in achieving multifunctionality. Top-down lithographic methods can produce multifunctional nanoparticles with precise size and shape control, yet this becomes increasingly difficult at sizes of ∼10 nm. Here, we report the fabrication of multifunctional, smart nanoparticle systems by combining top-down fabrication and bottom-up self-assembly methods. Particularly, we template nanorods from a mixture of superparamagnetic Zn0.2Fe2.8O4 and plasmonic Au nanocrystals. The superparamagnetism of Zn0.2Fe2.8O4 prevents these nanorods from spontaneous magnetic-dipole-induced aggregation, while their magnetic anisotropy makes them responsive to an external field. Ligand exchange drives Au nanocrystal fusion and forms a porous network, imparting the nanorods with high mechanical strength and polarization-dependent infrared surface plasmon resonances. The combined superparamagnetic and plasmonic functions enable switching of the infrared transmission of a hybrid nanorod suspension using an external magnetic field.

PMID:
27819691
DOI:
10.1038/nnano.2016.235

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