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Gold nanosystems for the detection of molecules using surface-enhanced Raman scatterings (SERS)
Benešová, Markéta
Raman spectroscopy is a non-destructive analytical technique to analyze the chemical structure of molecules by a phenomenon known as Raman scattering, which occurs by an inelastic interaction of photons with the valence electrons in molecular bonds. However, Raman scattering can be hard to observe due to other, more frequent phenomena, such as Rayleigh scattering or fluorescence. SERS (surface-enhanced Raman spectroscopy) uses localized surface plasmon resonance (LSPR) of metal nanostructures to amplify Raman scattering. LSPR is a coherent oscillation of conduction electrons that arises from the interaction of electromagnetic radiation with metal nanostructures. The amplification of Raman scattering occurs when the analyte is adsorbed on the surface of such nanostructure and the strong localized electric field interacts with the electrons in its molecular bonds. Signal amplification of several orders of magnitude can be achieved, commonly 103 or more. In our work, we determined the presence of a selected bacterial species by multi-functionalized golden nanoparticles called SERS-tags, which have their surface modified with an antibody and a Raman reporter. The antibody allows the nanoparticles to bind to the surface of a concrete bacterial species based on the antigen-antibody affinity. When the targeted bacterium is covered with the nanoparticles, the Raman reporter signal is amplified by SERS, providing specific and strong Raman response. Therefore, when the Raman reporter signal is detected in a sample, it confirms the presence of the specific bacterium on a single-cell level.
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Spectroscopy study of metal complexes with terpyridyl ligands
Kožíšek, Jan ; Šloufová, Ivana (advisor) ; Procházka, Marek (referee)
The work is focused on preparation and characterization of octahedral Fe(II) complexes of 2,2′:6′,2′′-terpyridine (tpy) substituted in 4' position by various groups: Cl (tpyCl), chlorophenyl (tpyPhCl) and 2-thienyl (Ttpy)). Formation and stability of prepared complexes were studied by UV/vis spectroscopy on the basis of titration of tpy ligands by Fe(II) ions. The molar absorption coefficient of the metal-to-ligand charge transfer (MLCT) band was found to increase in the order: tpy < tpyCl < tpyPhCl < Ttpy. The MLCT band position increases in the same order, starting from 551 nm for [Fe(tpy)2]2+ to 576 nm for [Fe(Ttpy)2]2+ . Raman scattering (RS) spectra of tpy ligands were obtained upon non-resonance 780 nm excitation. Four excitation wavelengths (445, 532, 633 a 780 nm) were used for measurement Fe(II) complexes. The excitation profiles of both Raman scattering and surface-enhanced Raman scattering (SERS) spectra were constructed for [Fe(tpyCl)2]2+ complex. On the basis of DFT calculations performed for this complex, the Raman active modes have been assigned to the symmetry species of the D2d point group. Similarly as for the previously studied [Fe(tpy)2]2+ complex, activation of E modes in the region of MLCT band suggests contribution of Herzberg-Teller mechanism to the overall molecular...
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Application of micro-Raman spectroscopy to analysis of artworks
Váňová, Hana ; Němec, Ivan (advisor) ; Šloufová, Ivana (referee)
This thesis deals with the application of micro-Raman spectroscopy to analysis of artworks. The main topic of the thesis was to qualify, select and eventually optimize methods acceptable to identification of indigo dye in the paint layers of artworks. Selected dye was studied in various states using set of excitation lasers emitting in the visible region. There was also studied the real usage of resonance and surface-enhanced methods. The result of the thesis are the conclusions related with the suitability of particular techniques of Raman spectroscopy to identify the target pigment in the art.
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Spectroscopy study of metal complexes with terpyridyl ligands
Kožíšek, Jan ; Šloufová, Ivana (advisor) ; Procházka, Marek (referee)
The work is focused on preparation and characterization of octahedral Fe(II) complexes of 2,2′:6′,2′′-terpyridine (tpy) substituted in 4' position by various groups: Cl (tpyCl), chlorophenyl (tpyPhCl) and 2-thienyl (Ttpy)). Formation and stability of prepared complexes were studied by UV/vis spectroscopy on the basis of titration of tpy ligands by Fe(II) ions. The molar absorption coefficient of the metal-to-ligand charge transfer (MLCT) band was found to increase in the order: tpy < tpyCl < tpyPhCl < Ttpy. The MLCT band position increases in the same order, starting from 551 nm for [Fe(tpy)2]2+ to 576 nm for [Fe(Ttpy)2]2+ . Raman scattering (RS) spectra of tpy ligands were obtained upon non-resonance 780 nm excitation. Four excitation wavelengths (445, 532, 633 a 780 nm) were used for measurement Fe(II) complexes. The excitation profiles of both Raman scattering and surface-enhanced Raman scattering (SERS) spectra were constructed for [Fe(tpyCl)2]2+ complex. On the basis of DFT calculations performed for this complex, the Raman active modes have been assigned to the symmetry species of the D2d point group. Similarly as for the previously studied [Fe(tpy)2]2+ complex, activation of E modes in the region of MLCT band suggests contribution of Herzberg-Teller mechanism to the overall molecular...
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Application of micro-Raman spectroscopy to analysis of artworks
Váňová, Hana ; Němec, Ivan (advisor) ; Šloufová, Ivana (referee)
This thesis deals with the application of micro-Raman spectroscopy to analysis of artworks. The main topic of the thesis was to qualify, select and eventually optimize methods acceptable to identification of indigo dye in the paint layers of artworks. Selected dye was studied in various states using set of excitation lasers emitting in the visible region. There was also studied the real usage of resonance and surface-enhanced methods. The result of the thesis are the conclusions related with the suitability of particular techniques of Raman spectroscopy to identify the target pigment in the art.
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