High-strength magnetically switchable plasmonic nanorods assembled from a binary nanocrystal mixture.
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 Zn0.2Fe2.8O4and plasmonic Au nanocrystals. The superparamagnetism of Zn0.2Fe2.8O4prevents 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.
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|The Nature Conservancy, Arlington, Virginia 22203, USA.
Mingliang
M
Zhang
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Daniel J
DJ
Magagnosc
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Iñigo
I
Liberal
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Yao
Y
Yu
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Hongseok
H
Yun
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|The Nature Conservancy, Arlington, Virginia 22203, USA.
Haoran
H
Yang
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Yaoting
Y
Wu
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Jiacen
J
Guo
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Wenxiang
W
Chen
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Young Jae
YJ
Shin
Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
Aaron
0000-0003-4424-5416
A
Stein
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
James M
JM
Kikkawa
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Nader
0000-0003-3219-9520
N
Engheta
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Materials Department, University of California Santa Barbara, Santa Barbara, California 93106, USA.
Daniel S
DS
Gianola
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Christopher B
CB
Murray
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.|Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Cherie R
CR
Kagan