XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
22
I–4
Synchrotron-based UV resonant Raman scattering experiments:
a powerful way to better investigate the structural conformation
in bio-macromolecules
Francesco D’Amico
1
, Barbara Rossi
1
, Cettina Bottari
1,2
, Paolo Zucchiatti
1,2,3
,
Sara Catalini
1
, Alessandro Gessini
1
, and Claudio Masciovecchio
1
1
Elettra Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5 in Area Science Park, I-34149 Trieste, Italy,
e-mail: francesco.damico@elettra.eu
2
Department of Physics, University of Trieste, via A. Valerio, 2, 34127 Trieste, Italy
3
IIT, Via Morego, 30 16163 Genova, Italy
Ultra-violet resonant Raman (UVRR) is widely used to investigate organic systems whenever the
complexity of the molecules analyzed do not allow to get an easy and unique interpretation of the
spontaneous Raman vibrational spectra. One of the most important applications of UV resonant
Raman in the deep-UV range (below 300 nm) is the investigation of peptides systems and
nucleotides. Both these issues require the use of an UV laser source able to generate the excitation
wavelengths needed to selectively approach the energy of resonances occurring in the specific system.
Although these class of measurements are generally performed by using fixed energy lasers, the
possibility of having, instead, a tunable radiation source in the deep-UV range allow to “map” the
whole resonance landscape range. First, it allows a better selection of the resonant conditions, even by
applying small changes in the excitation energies. Secondary, by an attempt choice of such excitation
energy it is possible to match experimental conditions where the sample self-absorption is negligible
but their pre-resonance effects are sufficiently marked to enhance specific Raman bands.
In this contribution, we will introduce the synchrotron-based resonant Raman scattering
instrument working in the UV spectral range, newly developed on IUVS at Elettra synchrotron
radiation facility in Trieste. Two selected case studies of biological relevance will be discussed in
order to show the potentiality of this Raman set-up to carry out results otherwise difficult to be
obtained. The first is the enhancement of the Amide band intensity in model peptide systems above
230 nm of excitation wavelength. By using specific small peptides model systems as NAGMA and
NALMA we have discovered the the Amide-II band strongly enhances its intensity between 270 and
230 nm on incident radiation. These findings have been explained by means of quantum mechanics
simulations. As second example, we report on the possibility of a fine tuning of the excitation
wavelength that allows a complete characterization of DNA and RNA extracted from B16 (mouse
melanoma) and T98G (human glioblastoma) tumor cell lines. We demonstrate that it is possible to
approach the resonance of the π-π* electronic transitions of the oligonucleotide DNA nitrogenous
bases, through a progressive decreasing of the energy radiation from 260 to 228 nm. In this
conditions, the vibrational bands arising from adenine and guanine residues can be selectively
enhanced. On the contrary, the excitation at 228 nm provides a significant increasing in the intensity
of the vibrational modes associated to the cytosine residue, giving the possibility to disentangle in the
complex spectra of DNA the single contributions corresponding to specific nucleobases. By a direct
comparison of the Resonant Raman measurements at 228 nm of DNA and RNA, we appreciated
slight spectral differences associated to the vibration of cytosine residues. Since cytosine methylation
is a phenomenon that involves only DNA strands and due the tumorigenic nature of the cell
population investigated, we hypothesized that this variation could be due to the presence of cytosine
methylation.
Keywords: UV Resonant Raman; peptides; proteins; nucleotides; DNA
References
[1] S. A. Oladepo, K. Xiong, Z. Hong, S. A. Asher, J. Handen, I. K. Lednev, Chem. Rev. 112 (2012)
2604.
[2] F. D’Amico, F. Cammisuli, R. Addobbati, C. Rizzardi, A. Gessini, C. Masciovecchio, B. Rossi, L.
Pascolo, Analyst. 140 (2015) 1477.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
23
I–5
Hybrid colloidal particles
Maciej Mazur
1
, Paulina Głowala
1
, Marta Bartel
1
, Barbara Wysocka
1
, Pamela Krug
1
,
Marta Kwiatkowska
1
, Ilona Mojzych
1
and Jarosław Wojciechowski
1
1
Department of Chemistry, University of Warsaw, Pasteura 1. 02-093 Warsaw, Poland,
e-mail: mmazur@chem.uw.edu.pl
Preparation of smart colloidal particles has been a hot topic of research in recent years.
Multifunctional colloids can serve several tasks simultaneously, which is promising in a range of
domains, including chemical analysis, catalysis, energy storage and medicine. In medicine, for
example, the colloidal particles can function simultaneously as drug carriers and diagnostic
probes. The idea of integration of therapy and diagnostics in one type of structure, called
theranostics, has gained much attention recently.
In the following presentation we will review our recent research efforts focused on
preparation and characterization of hybrid colloidal particles. Such species consist of organic
and inorganic constituents, which provide multiple functionalities to these structures like
targeting, recognition or sensing. A range of structural motifs and be employed for this purpose
which includes core-shell structures, capsules, hemispherical and spherical particles, etc. For the
experimental characterization of hybrid colloid particles a range of physicochemical techniques
can be used with spectroscopic methods being exceptionally powerful and effective. We will
show how modern spectroscopy can provide valuable information on particle chemistry at the
molecular level.
Fig. 1. Scanning electron microscopy (SEM) (a) and transmission electron microscopy (TEM) (b) of polystyrene
microsphere modified with magnetic nanoparticles; SEM (c) and TEM (d) images of biodegradable microspheres
(PLGA) decorated with gold nanoparticles; fluorescence microscopy of: polystyrene microparticles with
incorporated pyrene (e) and modified with magnetic nanoparticles (f), melamine-formaldehyde particles with
incorporated mRNA cap analogue (g), PLGA particles with embedded doxorubicin.
Acknowledgment
This work was supported by the National Science Centre, project no. UMO-2015/17/N/ST4/03926.
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