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Gold‐Cobalt Nanoparticle Alloys Exhibiting Tunable Compositions, Near‐Infrared Emission, and High T 2 Relaxivity
Author(s) -
Marbella Lauren E.,
Andolina Christopher M.,
Smith Ashley M.,
Hartmann Michael J.,
Dewar Andrew C.,
Johnston Kathryn A.,
Daly Owen H.,
Millstone Jill E.
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201400988
Subject(s) - materials science , cobalt , nanoparticle , analytical chemistry (journal) , spectroscopy , photoluminescence , transmission electron microscopy , x ray photoelectron spectroscopy , particle (ecology) , particle size , mass spectrometry , nuclear magnetic resonance , nanotechnology , chemistry , optoelectronics , organic chemistry , oceanography , quantum mechanics , geology , chromatography , physics , metallurgy
We demonstrate the synthesis of discrete, composition‐tunable gold‐cobalt nanoparticle alloys (% Co = 0–100%; diameter = 2–3 nm), in contrast with bulk behavior, which shows immiscibility of Au and Co at room temperature across all composition space. These particles are characterized by transmission electron microscopy and 1 H NMR techniques, as well as inductively coupled plasma mass spectrometry, X‐ray photoelectron spectroscopy, and photoluminescence spectroscopy. In particular, 1 H NMR methods allow the simultaneous evaluation of composition‐tunable magnetic properties as well as molecular characterization of the colloid, including ligand environment and hydrodynamic diameter. These experiments also demonstrate a route to optimize bimodal imaging modalities, where we identify Au x Co y NP compositions that exhibit both bright NIR emission (2884 m −1 cm −1 ) as well as some of the highest per‐particle T 2 relaxivities (12200 m m NP −1 s −1 ) reported to date for this particle size range.