XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
67
T1: O–25
Spherical nanoparticles of silica-calcia glass:
synthesis and spectroscopic characterization
Anna Łukowiak
1
, Beata Borak
2
, Justyna Krzak
2
, Maciej Ptak
1
, and Wiesław Stręk
1
1
Institute of Low Temperature and Structure Research, PAS, Wroclaw, Poland,
e-mail: A.Lukowiak@int.pan.wroc.pl
2
Department of Mechanics, Materials Science and Engineering, Wroclaw University of Science and
Technology, Wroclaw, Poland
As compared to the conventional bioactive glasses obtained by the melt-quenching
technique, the materials obtained by the sol–gel method often demonstrate higher bioactivity. In
general, such processing arrives to the formation of samples with high surface area rich in
silanol groups that increases the degradation rate and promotes the formation of the hydroxy
carbonate apatite layer. Other advantage of this technology is the possibility of glass doping
with different molecules, e.g. luminescent and organic bioactive species. Different spectroscopic
techniques allow to determine the structure, composition or optical properties of these
biomaterials.
In the presented work, the modified Stoeber method was used to synthesize nanosized SiO
2
–
CaO and SiO
2
–CaO–P
2
O
5
glass. Two-steps acid–base hydrolysis resulted in spherical particles
with average diameter of around 90 nm. Amorphous material was transferred to glass-ceramic
system when annealed at temperatures above 800°C as was shown by X-ray diffraction patterns.
Energy dispersive X-ray and inductively coupled plasma atomic emission spectrometry analyses
confirmed the glass composition.
Silica–calcia samples doped with Eu
3+
ions were also prepared. The absorption and
photoluminescence spectroscopy techniques were used to describe their optical properties.
Modification of the glass structure (crystallization occurred during annealing at different
temperatures) were observed as changes in the emission spectra of Eu
3+
. Eventually, Raman and
FTIR spectra indicated the apatite layer formation after immersion of the particles in the
simulated body fluid.
Keywords: sol–gel; nanoparticles; bioactive glass; europium
Acknowledgment
This research was supported by the National Science Centre research grant No. 2016/22/E/ST5/00530.
Authors would like to acknowledge Ewa Bukowska for XRD measurements.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
68
T1: O–26
Correlations between the frequency shifts and the thermodynamic
quantities for the α-β transition in quartz
M. Cem Lider
1
, Hamit Yurtseven
2
1
Middle East Technical University, Turkey,
2
Middle East Technical University, Turkey, e-mail: hamit@metu.edu.tr
The frequency shifts are related to the thermodynamic quantities (compressibility, order
parameter and susceptibility) for the α-β transition in quartz. The experimental data for the
frequency shifts and the bulk modulus from the literature are used for those correlations. By
calculating the order parameter from the mean field theory, correlations between the frequencies
of various modes and the order parameter are examined according to quasi-harmonic phonon
theory for the α-β transition in quartz. Also, correlation between the bulk modulus in relation to
the frequency shifts and the order parameter susceptibility is constructed for the α-β transition in
this crystalline system.
Keywords: frequency shifts, thermodynamic quantities, α-β transition, quartz
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
69
T2: O–1
Quantitative fluorescence spectroscopy of pigmented
and non-pigmented tissues
Paszcza Pawel
1
, Szczygieł Małgorzata
2
, and Matuszak Zenon
1
1
Department of Medical Physics and Biophysics, Faculty of Physics and Applied Computer Science,
AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow, Poland,
e-mail: Zenon.Matuszak@fis.agh.edu.pl
2
Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian
University, 7 Gronostajowa St., 30-387 Krakow, Poland
Photodynamic therapy (PDT) is based on the dye-sensitized photooxidation of biologically
important cell structures. Direct cell kill is caused by damage to plasma membranes or
mitochondria. In PDT, a tissue containing dye is exposed to light, mainly corresponding to
wavelength at maximum of its absorption. The dye (PS-photosensitizer) is transformed from its
ground state to excited triplet state, interacts with oxygen, transfers its energy directly to oxygen
to form highly reactive singlet oxygen (type II reaction). This type of therapy has some
advantages: PS is non-toxic for organism before irradiation, selectivity is obtained by
localization of PS in tissue and photodynamic damage is restricted to irradiated tissue area. PS
used in PDT are often fluorophores and monitoring of their fluorescence allows the localization
of the tumor, determination of PS concentration, and definition of tissue margins for light
delivery. However, with tissues being turbid media, their absorption and scattering properties
influence strongly both excitation and emission photons transport, as a consequence ─ the
intensity and shape of PS emission. Due to these complications, absolute quantification of drug
fluorescence (and concentration in tissue) is complex [1]. We were particularly interested in
quantitative PDT of melanoma, and how to predict concentration and shape of fluorescing dye
in tissue. The aim of this study was to elaborate and test a simple method of quantification of PS
(hematoporphyrin, eosin, fluorescein, rose bengal) in tissue mimicking phantoms using various
detection configurations: absorption and fluorescence spectrometry with fiber optics detection
and plate-reader. Non-pigmented tissues were simulated by Intralipid solutions, a good model of
scattering properties of tissues. Pigmented tissues were mimicked by mixtures of Intralipid and
synthetic melanin in various proportions. The Monte Carlo method (modified codes – MCML,
MCVM) was used to quantify spatial distributions of excitations/emission photons in both non-
pigmented and pigmented tumor tissues, true excitation/emission spectrum were simulated for
each fluorophore for various experimental conditions. Reflectance spectra and visual appearance
of pigmented tissue phantoms was simulated additionally. Optical properties of tissue phantoms
used in simulations are based on measured and reported (literature) values. Volumetric
distributions of both, fluorescence excitation and emission spectra were obtained as functions of
tissue optical properties for different PS and melanin concentrations. It was demonstrated that:
(1) emitted fluorescence intensity is a function of the depth of fluorescence generation, (2)
strong influence of melanin content on the intensity and shape of PS emission (more than 10
times delay). Diffuse reflectance was calculated separately as a function of melanin
concentration, and compared with skin appearance, giving visual criterion for estimation
melanin content within tissues layers. It was demonstrated that the models used are able to
predict the spatial distribution of the PS fluorescence excitation/emission pattern within skin
phantoms as functions of PS and melanin concentrations. Only in the case of non-melanized
tissues was it possible to predict distribution of PS, concentration and spectrum shape within
tissue on the basis of its fluorescence intensity with high accuracy.
Keywords: photosensitizers, fluorescence, Monte Carlo simulation, melanin
Dostları ilə paylaş: |