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Experimental and scaled Raman spectra of the anti-HIV nucleoside
analogue AZT (Zidovudine, Retrovir).
Comparison with the thymidine nucleoside
M. Alcolea Palafox
1,2
, D. Kattan
1,2
, and A. Nils Kristian
2
1
Departamento de Química-Física I, Facultad de Ciencias Químicas, Universidad Complutense,
Madrid-28040, Spain, e-mail: alcolea@ucm.es
2
Nofima AS – the Norwegian Institute of Food, Fisheries and Aquaculture Research, Osloveien 1,
1430 Ås, Norway
The nucleoside HIV-1 reverse transcriptase inhibitor AZT (3’-azido-3’-deoxythymidine),
Fig. 1, is a potent inhibitor of HIV-1 replication and it was the first clinically successful drug for
AIDS and AIDS-related diseases [1–3]. Despite the numerous drawbacks, AZT remains as one
of the key drugs used in the treatment and prevention of HIV infection in both monotherapy and
HAART. The scaled Raman spectra in the two most stable conformers of AZT in the biological
active anti-form were compared with the experimental one recorded in the solid state. The
calculated wavenumbers were determined at several DFT levels, and they were scaled by using
the linear scaling equation procedure (LSE) [4] and the polynomic equation. The FT-Raman
spectrum was recorded on a Nicolet Raman 950 at room temperature. Raman spectra were
exported to the Unscrambler software [5]. A data pre-treatment routine will be applied to
remove the fluorescent background intensities from Raman spectra [6]. EMSC was used for
normalization of the spectra [5]. Comparison of the spectra with those of the natural nucleoside
thymidine (T) (Fig. 1) was carried out. All the vibrational bands were analysed and assigned to
different normal modes of vibration.
a)
b)
a)
b)
Fig. 1. Structure of: (a) AZT, (b) Thymidine. Fig. 2. Optimized cluster of: (a) AZT (H
2
O)
13
, (b) T (H
2
O)
13
.
The simulated IR and Raman spectra of several optimized clusters of AZT (H
2
O)
15
(Fig. 2a)
were compared with those of thymidine (Fig. 2b). The clusters selected correspond to the best
conformers in the anti, high-anti, and syn orientation of AZT and thymidine molecules.
Comparisons with the experimental ones were carried out using different amount of water. Syn
forms were less stable than anti, and they were not observed in the spectra.
Keywords: AZT; scaling; simulated spectra
Acknowledgment
MAP wish to thank to BSCH-UCM PR26/16 for financial support.
References
[1] M. Alcolea Palafox, J. Talaya, J. Phys. Chem. B 114 (2010) 15199.
[2] N. Jain, S. Prabhakar, R.A. Singh, J. Molec. Struct. 1036 (2013) 414.
[3] M. Alcolea Palafox, Phys. Chem. Chem. Phys. 16 (2014) 24763.
[4] M. Alcolea Palafox, Phys. Sci. Reviews, in press (2017) doi. 10.1515/psr-2016-0132.
[5] H. Mohamadi Monavar, N.K. Afseth, J. Lozano, R. Alimardani, M. Omid, J.P. Wold, Talanta 111 (2013) 98.
[6] J.F. Brennan, Y. Wang, R.R. Dasari, M.S. Feld, J. Appl. Spectros. 51 (1997) 201.
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Structural and optical properties of HEMA-based polymers
for ophthalmological applications
Katarzyna Filipecka
1
, Małgorzata Makowska-Janusik
1
, Jacek Filipecki
1
1
Institute of Physics, Faculty of Mathematics and Natural Science, Jan Dlugosz University,
al. Armii Krajowej 13/15, 42-200 Czestochowa, Poland, e-mail: katarzyna.filipecka@ajd.czest.pl
Polymers based on 2-hydroxyethyl methacrylate (HEMA) are suitable materials for medical
applications. Especially they have been widely exploited for synthesis of contact lenses [1] and
investigated as materials delivering of ophthalmic drugs [2, 3]. HEMA has excellent
biocompatibility exhibiting properties similar to living tissue. It contains hydroxyl functional
groups on its surface that can be used for protein bioconjugation [4]. Additionally, HEMA can
be copolymerized with large group of other monomers changing its properties.
An important step in the design of novel biomaterials is to understand their properties at the
molecular level. As a powerful tool to provide insight into materials structure at the molecular
level and giving information concerning dynamics properties of investigated environment the
molecular dynamics simulations techniques have been evolved. In this work, the HEMA-based
polymeric systems were studied using molecular dynamics (MD) simulations in order to
investigate the effect of the water content on their structural and dynamic properties. The MD
simulations were performed using the Forcite software from the Materials Studio package. The
DREIDING force field [5, 6] was applied for MD simulations. All systems were evaluated
during 5 ns in isothermal-isochoric (NVT) ensemble controlled by Nose thermostat at 307 K.
Analyzing the radial distribution function the local polymeric structure was investigated and the
water effect was examined. Theoretically obtained data were compared with experimental
studies performed by PALS technique analyzing free volumes created in the polymer.
Keywords: Polymers, Hydrogels, Molecular Dynamics, Simulation, Free volumes
Acknowledgment
Quantum chemical calculations have been carried out in Wroclaw Center for Networking and
Supercomputing http://www.wcss.wroc.pl (Grant no. 171). The MATERIALS STUDIO package was used
under POLAND COUNTRY-WIDE LICENSE.
References
[1] T. Goda, K. Ishihara, Expert. Rev. Med. Devices. 3 (2006) 167.
[2] L. Chi-Chung, C. Anuj, Ind. Eng. Chem. Res. 45 (2006) 3718.
[3] L. Chi-Chung, C. Anuj, J. Drug Deliv. Sci. Technol. 17 (2007) 69.
[4] L.G. Bach, M.R. Islam, Y.T. Jeong, Y.S. Gal, K.T. Lim, Appl. Surf. Sci. 253 (2012) 2816.
[5] S.L. Mayo, B.D. Olafson, W.A. Goddard, J. Phys. Chem. 94 (1990) 8897.
[6] Online manual of Material Studio, http://accelrys.com/products/materials-studio/.
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