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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
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T3: P–6
SERS study of riboflavin on biocompatible silver nanoparticles
prepared by reduction using different flavonoids
Marie Švecová
1
, Marcela Dendisová
2
, and Pavel Matějka
2
1
Department of Analytical Chemistry, University of Chemistry and Technology Prague, Technická 5,
Prague, Czech Republic, e-mail: svecovam@vscht.cz
2
Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5,
Prague, Czech Republic
Surface-enhanced Raman scattering (SERS) is a valuable tool for detection of low amount
samples and compounds. Nowadays, the non-toxicity and biocompatibility of enhancing
substrates is crucial to employ SERS in the field of medicine and/or food analysis. These
properties exhibit silver plasmonic nanoparticles prepared by so called green synthesis, because
inorganic Ag salts are reduced by natural compounds/products. Flavonoids are good
representatives of natural compounds with antioxidant properties.
The group of flavonoids includes many structurally similar compounds, which differ in type
(hydroxyl, methoxy group or hydrogen) and position of substituents. These differences in the
structure can significantly affect both reducing capabilities and deposition/adsorption of
compounds on the enhancing surface [1]. For SERS spectroscopy, the amount of reducing agent
adsorbed on the enhancing surface is a serious obstacle, because it avoids the analyte to deposit
on the surface. Flavonoids are compound without sulphur or nitrogen atoms in the structure (that
means with relatively low affinity to the metal surface) and can be quite easy removed from the
metallic surface by multiple centrifugation or dialysis.
In this work, 5 structurally similar flavonols and 5 flavones were used for systematic study
of their reduction properties. The flavonoids and silver salt solutions were mixed in aqueous
medium, than pH value was adjustment by sodium hydroxide solution (value was optimized for
every flavonoid). Prepared silver nanoparticles (AgNPs) were stabilized by higher temperature
at 40 or 70°C. Novel AgNPs are required to be characterized by X-ray powder diffraction
(XRPD, confirmation of silver oxidation state), transmission electron microscopy (TEM, shape
and size), dynamic light scattering (DLS, size distribution), absorption UV/Vis spectroscopy
(band of plasmon resonance) and Raman spectroscopy (deposited compounds on AgNPs
surface). For SERS study, riboflavin was used as model analyte (natural compound with positive
effect on human health and structurally similar to flavonoids). In conclusion, riboflavin
deposited on AgNPs surface prepared by flavonoid reduction can be detected down to 10
–9
mol/l
concentration.
Keywords: silver biocompatible plasmonic nanoparticles; flavonoids; surface-enhanced Raman scattering;
riboflavin
Acknowledgment
Financial support from specific university research (MSMT No 20-SVV/2017) is gratefully acknowledged.
References
[1] M. Dendisova-Vyskovska, G. Broncova, M. Clupek, V. Prokopec, P. Matejka Spectrochim. Acta A 99
(2012) 196.
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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
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T3: P–7
An integrated AFM-Raman instrument for studying heterogeneous
catalytic systems – example of multicomponent systems
deposited on kanthal steel
Damian K. Chlebda
1
, Przemysław Jodłowski
2
, Dominika Pawcenis
1
,
Roman Jędrzejczyk
3
, Magdalena Chrzan
1
, and Joanna Łojewska
1
1
Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060 Kraków, Poland,
damian.chlebda@uj.edu.pl
2
Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska
24, 30-155 Kraków, Poland
3
The Malopolska Centre of Biotechnology, Jagiellonian University, ul. Gronostajowa 7A, Krakow,
Poland
An inherent property of the catalyst surface is its heterogeneity, thus the development of new
characterization techniques for the determination of nanomaterial properties is crucial. The use
of the integrated AFM-Raman setup benefits in combined measurement of Raman maps with
AFM. The resolution of standard μRaman measurements depends on the excitation wavelength
used, typically not higher than 300 nm. The use of AFM enables to obtain topography images of
the catalysts with resolution below 1 nanometre. For the purpose of combined AFM-Raman
measurement the configuration of both microscopes can be different, however, the side and top-
view configuration is required since the catalysts support (commonly metal oxide) is not
transparent. A side-view setup is shown at Fig. 1. In the integrated setup, the Raman laser beam
is focused onto the end of the AFM tip and at every measured point. As a result, the AFM tip
response is acquired along with a Raman spectrum for any defined spectral region of interest.
Fig. 1. The Raman-atomic force microscope instrument in side-view configuration.
The integration of those two microscopes provides high-resolution AFM image
and targets the local enhancement of a Raman signal at the special AFM tip.
In this work, an AFM-Raman microscopes system in side-view configuration was used to
study laser-tip far field effects for characterisation of catalytic systems composed of different
oxides deposited metallic structured catalytic supports. The use of the integrated AFM-Raman
setup allowed for the characterization of the catalyst surfaces. The obtained AFM-Raman results
combined with the results of the catalytic combustion of methane allowed to define the
structure–activity relationships.
Keywords: AFM; Raman spectroscopy; catalysis; surface characterisation
Acknowledgment
Financial support for this work was provided by the National Science Centre, Poland – project no.
2015/19/N/ST8/00181 and project no. 2015/17/D/ST8/01252.
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