b2815 Tissue Engineering and Nanotheranostics “9.61x6.69”
124 Tissue Engineering and Nanotheranostics
attained by taking HRTEM images (Fig. 15(d)), which exhibited a
well-ordered porous Janus-shaped morphology.
In 2005, a research group from Brown University with a collabo-
ration of Stanford University synthesized magnetic hybrid dumbbell-
like Au/Fe 3 O 4 nanoparticles using thermal decomposition method.^87
Recently, almost the same method has been employed for Au–Fe 3 O 4
with little modification. Firstly, the seeds of AuNPs were grown and
then they were injected into the solution of iron pentacarbonyl,
Fe(CO) 5 , with different solvents at high temperature.^88
Firstly, chloroauric acid (HAuCl 4 ) solution was injected into the
surfactant such as oleylamine in the presence of organic solution to
prepare AuNPs. The temperature at which the gold precursor was
injected into the solution was important to control the size of the
particles. Afterwards, the prepared AuNPs seeds were mixed with
Fe(CO) 5 in 1-octadecene solvent in the presence of oleylamine and
oleic acid, heated at 300°C. Figures 16(a)–16(d) was prepared with
the similar method. The lattice constant for Fe 3 O 4 is 8.394 Å for
inverse spinel and gold in the FCC phase is 4.080 Å. The size of the
magnetic lattice is twice that of gold with a mismatch of about 3%
which facilitates epitaxial growth.^87 The crystal plane {111} was shown
direction in epitaxial growth as shown in Fig. 16(b). Similar kind of
work was reported by Manna et al. and is illustrated in Figs. 16(c)–
16(f). They obtained the dumbbell-shaped morphology in the absence
of dodecyl dimethyl ammonium bromide and got the heterostruc-
tures in the presence of DDAB as shown in Figs. 16(e) and 16(f).
DDAB has significant effect on structure and produced urchin-like
morphology at higher concentration of ammonium bromide.
Later, Nanfeng Zhang also reported the preparation method of
Au–Fe 3 O 4 dumbbell nanoparticles via conventional heating process.^89
Finally, they modified the surface of magnetic-plasmonic nanohybrids
using silica shell. The simple procedure is illustrated in Fig. 17(a). In
detail, the asymmetric Au–Fe 3 O 4 magnetic-nanohybrids were dis-
solved in cyclohexane solution of dodecanethiol to obtain a homoge-
neous dispersion and then the well-known reverse micro-emulsion
method with Brij C10 and NH 3 H 2 O was used for coating. Finally,
tetraethylorthosilicate (TEOS) was added into the above solution for
