XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
303
T6: P–11
SERS and DFT investigations of 99mTc-labeled radiopharmaceuticals
George Crisan
1,2
, Ana Maria Macea
1
, Gabriel Andries
2
, Loredana Leopold
3
,
and Vasile Chis
1
1
Faculty of Physics, “Babes-Bolyai” University, Kogalniceanu 1, 400086, Cluj-Napoca, Romania,
e-mail: george.crsn@gmail.com
2
Department of Nuclear Medicine, Emergency Clinical County Hospital Cluj, Clinicilor 3-5, 400006,
Cluj-Napoca, Romania
3
Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary
Medicine, Mănăștur 3-5, 400372 Cluj-Napoca, Romania
99mTc-labeled radiopharmaceuticals are the workhorse of a nuclear medicine department
[1], due to the convenient half-life (6 hours) of the Technetium radionuclide and the availability
through 99Mo/99mTc generators. Although widely used, the information in current literature
regarding the exact chemical structure of technetium radiopharmaceuticals as well as the ligands
themselves is scarce.
Hexakis(2-methoxy-2-methylpropylisonitrile) technetium (99mTc) (99mTc-sestamibi),
consisting of a 99mTc core bound to six Mibi ligands, is a radiolabeled drug commonly used for
myocardial, breast and parathyroid imaging.
This study presents a spectroscopic analysis of the 99mTc-sestamibi complex as well as its
corresponding ligand. Surface Enhanced Raman Spectroscopy measurements were performed on
the drug in solution as administered to patients at different times from the time of preparation in
order to monitor its stability. The recorded spectra were then compared with those of the Mibi
ligand. The experimental data was complemented with Density Functional Theory calculations
using the B3LYP hybrid exchange correlation functional and the 6-311+G (d,p) basis set.
Fig. 1. SERS spectra of 99mTc-sestamibi recorded at different times from the time of preparation.
Keywords: surface enhanced Raman Spectroscopy; density functional theory; technetium radiopharmaceuticals
References
[1] M.D. Bartholoma, A. S. Louie, J. F. Valliant, J. Zubieta , Chem. Rev. 110 (2010) 2903.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
304
T6: P–12
Advanced thermal analysis of aliphatic oligo-urethane
based on vibrational heat capacity
Anna Czerniecka-Kubicka
1
, Iwona Zarzyka
1
, and Marek Pyda
1
1
Department of Chemistry, The Rzeszow University of Technology, 35959 Rzeszow, Poland,
e-mail adress: anna_czerniecka@poczta.fm
The new quantitative thermal analysis (advanced thermal analysis) of semicrystalline
aliphatic oligo-urethane (OU) obtained from the reaction between butane-1,4-diol and
hexamethylene 1,6-diisocyanate has been presented. The advanced thermal analysis has been
based on vibrational, solid and liquid heat capacities. The equilibrium solid heat capacity was
estimated using the low-temperature heat capacity measured by a Quantum Design PPMS
(Physical Property Measurement System) in the temperature range of (2.04 to 302.5) K. The
experimental heat capacity data below the glass transition temperature of 280.2 K (7.05°C) were
interpreted in terms of molecular motion and were linked to the vibrational spectrum of oligo-
urethane structure. The presented approach applies the classical Einstein, Debye and Tarasov
treatments using the ATHAS Scheme [1]. The low-temperature solid heat capacity was
estimated by separately approximating the group and skeletal heat capacities from their
vibrational spectra. The group vibrational heat capacity was calculated based on the chemical
structure and molecular vibrational motions (Ngr = 90) derived from infrared and Raman
spectroscopy. The skeletal vibrational heat capacity contribution was estimated by a general
Tarasov equation with thirty skeletal modes (Nsk = 30). The solution of this equation gave the
values of characteristic Debye temperatures as: Θ1 = 493 K, Θ2 = 133.9 K, and Θ3 = 51.6 K.
The result indicates the existence of planer (Θ2) interactions in the oligo-urethane molecules, in
addition to linear (Θ1) and special (Θ3) interactions, which are attributed to a possible branched
structure mixed with the linear form of the oligomer. The total vibrational heat capacity, being
the sum of the group and skeletal heat capacities, was extended to higher temperatures and
analyzed further. The liquid heat capacity of semicrystalline aliphatic oligo-urethane was
approximated from experimental data by a linear regression and was compared with the
estimated linear contributions of polymers that have the same constituent groups. Using
estimated parameters of transitions and solid and liquid heat capacities at equilibrium, the
integral thermodynamic functions of enthalpy, entropy and free enthalpy as functions of
temperature were calculated [2].
The solid and liquid heat capacities of oligo-urethane were applied as equilibrium baselines
for advanced thermal analysis of the experimental, apparent heat capacity data. The apparent
heat capacity of OU was measured using the standard differential scanning calorimetry, (DSC)
and temperature – modulated DSC (TMDSC) and quantitative analysis allows for the study of
any glass transition, melting/crystallization process, and heat capacity of OU in entire range of
investigated temperature (190–470 K). The formation and description of phases during thermal
processes of OU by advanced thermal analysis were examined. The mobile amorphous fraction,
degree of crystallinity and rigid amorphous fraction were determined depending on thermal
history of semicrystalline OU. The experimental, apparent heat capacity of OU in non-
equilibrium state was analyzed in reference to the vibrational, solid and liquid heat capacities.
Keywords: vibrational heat capacity; aliphatic oligo-urethane; vibration spectrum
References
[1] ATHAS Data Bank. Available from Springer Materials (www.springermaterials.com).
[2] A. Czerniecka-Kubicka, I. Zarzyka, M. Walczak, J. Schliesser, M. Popovic, B. F. Woodfield, M.
Pyda, Molecular interpretation of low-temperature heat capacity of aliphatic polyurethane, J. Chem.
Thermodyn., in press.
Dostları ilə paylaş: |