Facile transformation of FeO/Fe3O4core-shell nanocubes to Fe3O4via magnetic stimulation.
Here, we propose the use of magnetic hyperthermia as a means to trigger the oxidation of Fe1-xO/Fe3-δO4core-shell nanocubes to Fe3-δO4phase. As a first relevant consequence, the specific absorption rate (SAR) of the initial core-shell nanocubes doubles after exposure to 25 cycles of alternating magnetic field stimulation. The improved SAR value was attributed to a gradual transformation of the Fe1-xO core to Fe3-δO4, as evidenced by structural analysis including high resolution electron microscopy and Rietveld analysis of X-ray diffraction patterns. The magnetically oxidized nanocubes, having large and coherent Fe3-δO4domains, reveal high saturation magnetization and behave superparamagnetically at room temperature. In comparison, the treatment of the same starting core-shell nanocubes by commonly used thermal annealing process renders a transformation to γ-Fe2O3. In contrast to other thermal annealing processes, the method here presented has the advantage of promoting the oxidation at a macroscopic temperature below 37 °C. Using this soft oxidation process, we demonstrate that biotin-functionalized core-shell nanocubes can undergo a mild self-oxidation transformation without losing their functional molecular binding activity.
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Aidin
A
Lak
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Dina
D
Niculaes
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
George C
GC
Anyfantis
IMEM-CNR, Parco Area delle Scienze 37/A, 43124 Parma, Italy.
Giovanni
G
Bertoni
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Markus J
MJ
Barthel
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Sergio
S
Marras
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Marco
M
Cassani
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Simone
S
Nitti
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Athanassia
A
Athanassiou
Institute of Crystallography, National Research Council, via Amendola 122/O, Bari 70126 Italy.
Cinzia
C
Giannini
Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
Teresa
T
Pellegrino
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