XIV
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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
134
T1: P–1
Fast synthesis of gold coated magnetic nanoparticles
László Szabó
1,2
, Andrei Stefancu
1,2
, Sever Mican
2
, Loredana F. Leopold
3
,
Zoltán Bálint
1,2
, Romulus Tetean
2
, and Nicolae Leopold
1,2
1
IMOGEN Research Institute, County Clinical Emergency Hospital, Cluj-Napoca, Romania,
e-mail: laszlo.szabo@phys.ubbcluj.ro
2
Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, Romania
3
Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary
Medicine, Cluj-Napoca, Romania
The spotlight of nanomaterial research turned on gold coated magnetic nanoparticles
(Au@MNPs), due to their multifunctional properties and their applicative potential in both
bioanalytics and nanomedicine [1]. MNPs have been used in the clinical environment for many
years, due to their good magnetic resonance imaging properties. Recently, the combination of
MNPs with other non-toxic materials, such as gold which in turn can be further modified with
biopolymers, allows for the agent to be used in different biomedical applications [1]. When used
as an imaging agent, the gold coating on the surface of MNPs decreases their oxidation and
toxicity as well as increases circulating half-life.
In this study we have used a fast and simple method to synthesize Fe
3
O
4
nanoparticles
without surfactants at room temperature [2]. X-ray diffraction data show that the nanoparticles
crystallize in a cubic single phase structure. An average crystallite size of around 24 nm was
calculated from the diffraction pattern [2]. In order to coat the Fe
3
O
4
nanoparticles with gold, a
citrate reduction methodology was adapted [3].
The successful coating of the MNPs with gold is indicated by the appearance of a plasmon
resonance band at around 560 nm in the UV-Vis absorption spectrum. Also, the gold coating can
be observed in the Transmission Electron Microscopy (TEM) micrographs (Figure 1).
Concluding, in this paper we present a fast and simple method for Au@MNPs nanoparticle
synthesis, which could be used in an efficient high-throughput setting.
Fig. 1. Representative micrograph of Au@MNPs obtained by TEM.
Keywords: gold coating; magnetic nanoparticles
Acknowledgement
L.Sz., A.S., Z.B. and N.L. highly acknowledge financial support from the Competitiveness Operational
Programme 2014-2020 POC-A1-A1.1.4-E-2015, financed under the European Regional Development
Fund, project number P37_245.
References
[1] S.
Moraes
Silva,
R.
Tavallaie,
L.
Sandiford,
R.D.
Tilley,
J.J.
Gooding,
Chem.
Commun.
52
(2016)
7528.
[2] G. Souca, S. Mican, A. Stefancu, V. Chiș, R. Tetean, N. Leopold, Studia Universitatis Babeş-Bolyai
Physica 61 (2016) 83.
[3] S.E. Hunyadi Murph, G.K. Larsen, R.J. Lascola, J. Visual. Experiments 108 (2016) 53598.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
135
T1: P–2
Boson peak dynamics of natural polymer starch
investigated by terahertz spectroscopy
Wakana Terao
1
, Tatsuya Mori
1
, Yasuhiro Fujii
2
,
Akitoshi Koreeda
2
, and Seiji Kojima
1
1
Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan,
2
Department of Physical Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan,
e-mail: mori@ims.tsukuba.ac.jp
Starch is a natural polymer formed by polymerization of a number of glucose molecules by
glycosidic linkage and has an amorphous structure. As a universal feature appearing in
amorphous materials, there is excitation called the boson peak in the terahertz region. The boson
peak is well known to be detectable by inelastic neutron scattering, Raman scattering, and low
temperature specific heat. However, it is not well known that the boson peak can be detected by
far-infrared (FIR) spectroscopy [1].
In this study, the boson peak dynamics of amorphous starch was investigated using terahertz
time-domain spectroscopy (THz-TDS) and low-frequency Raman spectroscopy. As shown in
Fig. 1, the boson peak of starch was observed at about 1.0 THz in the α(ν)/ν
2
spectrum obtained
by THz-TDS, where α(ν) is absorption coefficient. Comparing with the previous study of
glucose glass [1], we found that the boson peak frequency of starch in the FIR spectrum is about
10% lower than glucose glass, and the value of α(ν)/ν
2
is about 30 % smaller than the glucose
glass. The starch is a polymer of glucose molecules, and it is considered that the boson peak
frequency of starch is shifted to the lower frequency than glucose glass by increasing the
intermediate correlation length of the amorphous starch. The ratio of starch to glucose of α(ν) is
about 0.7 and it closes to the ratio 0.6 of the hydroxyl groups per unit structure. Therefore, the
value of α(ν) in the terahertz region might be proportional to the concentration of dipole moment
of glucose molecule.
0.0
0.5
1.0
1.5
2.0
0
10
20
30
40
50
300 K
250 K
200 K
150 K
100 K
33 K
α
/ν
2
(
cm
-1
T
H
z
-2
)
Frequency (THz)
300K
33K
Heating
Starch
Fig. 1. Boson peak plot α(ν) /ν
2
of starch on heating process obtained by THz-TDS.
Keywords: boson peak; terahertz time-domain spectroscopy; glass; starch; glucose
Acknowledgments
This work was partially supported by JSPS KAKENHI Grant No. 17K14318, the Nippon Sheet Glass
Foundation for Materials Science and Engineering, and the Asahi Glass Foundation.
Reference
[1] M. Kabeya, T. Mori, Y. Fujii, A. Koreeda, B. W. Lee, J. H. Ko, and S. Kojima, Physical Review B 94
(2016) 224204.
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