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Surface-enhanced Raman spectral detection of bilirubin and temporally synchronized monitoring of its photochemical transformations in selected solvents by SERS and electronic absorption spectroscopy
Hrnčířová, Jana ; Vlčková, Blanka (advisor) ; Procházka, Marek (referee)
Surface-enhanced Raman scattering (SERS)-active systems based on macroscopic Ag nanosponge aggregates as well as the conditions of SERS spectral measurements were optimized for selective and sensitive detection of a biomedically important, amphiphilic bile pigment bilirubin (BR) in alkaline aqueous solutions and in its solutions in a selected water miscible solvent, namely dimethylsulfoxide (DMSO) and/or water-immiscible solvent, namely CH2Cl2. Ag nanosponges assembled by using HCl as a pre-aggregation agent were found to be the optimal SERS-active systems for a reliable detection of BR in all the above-mentioned solvents. In all cases, the protonated form of adsorbed BR has been detected upon BR incorporation into Ag nanosponges, and its marker bands have been established by SERS spectral probing at excitation wavelengths in the 445-780 nm range. The sensitivity of SERS spectral detection was evaluated in terms of the concentration values of SERS spectral detection limits (SERS LODs) of BR incorporated into Ag nanosponges. In particular, the SERS LOD for BR incorporated from its alkaline aqueous solution is 1 x 10-8 M (at 532 nm excitation), for BR incorporated from its solution in DMSO, its value is also 1 x 10-8 M (at 532 and/or 633 nm excitations), and for incorporation from the solution of BR...
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SERS spectroscopy of model biomolecules for SERS biosensing
Šubr, Martin ; Procházka, Marek (advisor) ; Michl, Martin (referee)
Title: SERS spectroscopy of model biomolecules for SERS biosensing Author: Martin Šubr Department: Institute of Physics of Charles University Supervisor: doc. RNDr. Marek Procházka, Dr., Institute of Physics of Charles University Abstract: The main requirement for surface enhanced Raman scattering (SERS)-based biomolecular sensing is high sensitivity and spectral reproducibility. For this purpose, ordered silver and gold nanostructures fabricated by magnetron sputtering and lithography methods at cooperating institutes were tested in this work. Reproducible SERS spectra of employed model biomolecules (amino acids, lysozyme and albumin) were obtained on ordered silver surfaces at concentrations 10-4 M - 10-6 M and as low as ≈ 10-7 M in the case of porphyrins. SERS spectra of certain biomolecules were also compared to spectra measured on silver colloid. The limit of detection provided by hydroxylamine-reduced silver colloid, using KCl as an aggregating agent, is substantially lower (on the order of 10-8 M for cysteine), but with lower spectral reproducibility. The main drawback of SERS spectra measured on silver surfaces was the occurrence of spurious bands resulting from the preparation procedure. In the case of sputter-deposited silver surfaces, it was found that keeping the substrates several hours in...
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Surface-enhanced Raman microspectroscopy of biomolecules and biological systems
Šimáková, Petra ; Procházka, Marek (advisor) ; Michl, Martin (referee) ; Šloufová, Ivana (referee)
The aim of this thesis was using surface-enhanced Raman scattering (SERS) microspectroscopy for the study of biomolecules and biological systems. The main probe molecule was cationic porphyrin H2TMPyP, however, other porphyrins, tryptophan and two lipids were also used. The sensitivity and reproducibility of several solid SERS substrates: (i) Au and Ag nanoparticles (NPs) immobilized via a bifunctional linker, (ii) AgNPs immobilized by drying, (iii) highly ordered Au and Ag film-over-nanosphere (FON) and (iv) Ag-coated insect wings were compared. On most of the solid substrates, the lowest detected H2TMPyP concentration was ~10-8 M. The highest sensitivity was provided by the dried drops of AgNPs/analyte mixture, where concentrations 1×10-10 M TMPyP, 1×10-5 M tryptophan, 2×10-7 M DSPC and 3×10-7 M DMTAP were detected. Nevertheless, the spectral reproducibility was decreased due to porphyrin metallation and perturbation of the lipid spectra in comparison to their Raman spectra from solution. The highest reproducibility was achieved by AuFON and Ag-coated insect wings. Finally, the AgNPs modified by PEG polymers were tested for intracellular application using HeLa cancer cells. Metallation of H2TMPyP served to probe the accessibility of PEG- AgNPs surface. The results proved that the accessibility...
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Optimization of surface-enhanced Raman scattering spectroscopy for study of biologically important biomolecules and their interactions
Šmídová, Natália
Title: Optimization of surface-enhanced Raman scattering spectroscopy for study of biologically important biomolecules and their interactions Author: Natália Šmídová Department: Institute of Physics of Charles University Supervisor of the doctoral thesis: Doc. RNDr. Marek Procházka, PhD. Abstract: The main goal of this thesis was to optimize surface-enhanced Raman scattering (SERS) spectroscopy for study of biologically important biomolecules. For that purpose we focused on substrates based on gold colloidal nanoparticles immobilized to silanized glass plates. Stable, uniform and highly reproducible SERS-active substrates have been prepared by using aminopropyltrimethoxysilane and citrate- reduced gold nanoparticles thermally stabilized after their immobilization. Model biomolecules 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin (TMPyP) and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) were studied on these substrates by using a classical Raman spectrometer in macro-mode and a confocal Raman microspectrometer. Conditions for SERS spectroscopy of porphyrins were optimized with respect to sensitivity and reproducibility. SERS microspectroscopy showed several advantages over SERS measurements in macromode: possibility of surface spectral mapping, easier manipulation with samples, shorter...
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Assembling of Ag and Au nanoparticles mediated by terpyridine-based oligomers: Relationship between morphology and spectral characteristics
Prusková, Markéta
This work is aimed at the preparation and morphological and spectroscopic characterization of the interphase nanocomposite (NC) two-dimensional (2D) self-assembled systems of Ag and Au nanoparticles (NPs). The NPs were functionalized with the following ligands with terpyridine end-groups: 2,2′:6′,2′′-terpyridine (tpy), 4'-(2-thienyl)-2,2':6',2''-terpyridine (T-tpy), α,ω-bis(terpyridyl)-2,2'-bithiophene (tpy-2T-tpy) and α,ω-bis(terpyridyl)-2,2':5',2''- terthiophene (tpy-3T-tpy). The morphological analysis of transmission electron micrographs proves the preservation of the average interparticle distance in closely spaced NP pairs, independent of the ligand. The value of the total average interparticle distance increases in the order: tpy < T-tpy < tpy-2T-tpy < tpy-3T-tpy, while the average occupied area fraction in the same order decreases. The morphological descriptors (i.e. interparticle distance and occupied area fraction) were found to correlate with the shift of the SPE (surface plasmon extinction) maxima of NCs (tpy > T-tpy > tpy-2T-tpy > tpy-3T-tpy). The results show that the shift of SPE band maximum depends on the degree of surface plasmon delocalisation rather than on the value of the average interparticle distance in closely spaced NP pairs. The smaller are the islands formed by closely...
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Optimization of new active surfaces based on plasmonic nanoparticle assemblies for SERS, SERRS and surface-modified luminescence studies of selected molecules
Sutrová, Veronika
Two types of 3-dimensional (3D) Ag nanosponge aggregates were prepared and tested as samples for surface-enhanced Raman scattering (SERS) and as active surfaces for surface-enhanced luminescence. 3D Ag nanosponge aggregates were assembled from 2D fused fractal aggregates (D = 1.87 ± 0.02) prepared by modification of Ag nanoparticle (NP) hydrosol resulting from the reduction of AgNO3 by NH2OH∙HCl. For SERS measurements, 3D Ag nanosponge aggregates with incorporated [Ru(bpy)3]2+ cations and chloride anions were prepared and overlayed by a thin layer of aqueous phase. For SEL measurements, the 3D Ag nanosponge aggregates were assembled from fused fractal aggregates of chloride-modified Ag NPs. After preparation the active surface was overlayed by a 1×10-5 M aqueous solution of [Ru(bpy)3]2+ . The SERRS (1×10-15 M) and SER(R)S (1×10-14 M) limits of detection of [Ru(bpy)3]2+ determined at 445 and 532 nm excitations, respectively, correspond to the single molecule level of the complex detection. Its achievement is attributed to a large electromagnetic mechanism enhancement experienced by [Ru(bpy)3]2+ incorporated in "hot spots", an efficient localization of "hot spots" in the 3D aggregate to the focus of the laser beam in micro-Raman spectral measurements and to a molecular resonance contribution to the...
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Ionic polyacetylene type polymers and polymer networks by catalyst-free quaternization polymerization
Faukner, Tomáš
(Doctoral Thesis, 2016, Mgr. Tomáš Faukner, IONIC POLYACETYLENE TYPE POLYMERS AND POLYMER NETWORKS BY CATALYST FREE QUATERNIZATION POLYMERIZATION) The composition and structure of a series of ionic π-conjugated poly(monosubstituted acetylene)s prepared via catalyst-free quaternization polymerization (QP) of 2-ethynylpyridine (2EP) activated with equimolar amount of alkyl halide [RX = ethyl bromide, ethyl iodide, nonyl bromide and haxadecyl (cetyl) bromide] as a quaternizing agent (QA) have been studied in detail. The performed QPs gave ionic polymers well soluble in polar solvents, with approximately half of pyridine rings quaternized, which implies that also non-quaternized monomers were involved in the process of QP. The configurational structure of polyacetylene main chains was suggested based on 1 H NMR, IR as well as Raman (SERS) spectral methods. The QPs in bulk gave more expected irregular cis/trans polymers while the QPs in acetonitrile solution gave high-cis polymers. A series of prepared symmetrical bi-pyridylacetylene based monomers has been polymerized via QP approach resulting into a series of new ionic π-conjugated poly(disubstituted acetylene) type materials. It is therefore obvious that the mechanism of quaternization activation frequently applied on monosubstituted...
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Surface-enhanced Raman spectral detection of bilirubin and temporally synchronized monitoring of its photochemical transformations in selected solvents by SERS and electronic absorption spectroscopy
Hrnčířová, Jana ; Vlčková, Blanka (advisor) ; Procházka, Marek (referee)
Surface-enhanced Raman scattering (SERS)-active systems based on macroscopic Ag nanosponge aggregates as well as the conditions of SERS spectral measurements were optimized for selective and sensitive detection of a biomedically important, amphiphilic bile pigment bilirubin (BR) in alkaline aqueous solutions and in its solutions in a selected water miscible solvent, namely dimethylsulfoxide (DMSO) and/or water-immiscible solvent, namely CH2Cl2. Ag nanosponges assembled by using HCl as a pre-aggregation agent were found to be the optimal SERS-active systems for a reliable detection of BR in all the above-mentioned solvents. In all cases, the protonated form of adsorbed BR has been detected upon BR incorporation into Ag nanosponges, and its marker bands have been established by SERS spectral probing at excitation wavelengths in the 445-780 nm range. The sensitivity of SERS spectral detection was evaluated in terms of the concentration values of SERS spectral detection limits (SERS LODs) of BR incorporated into Ag nanosponges. In particular, the SERS LOD for BR incorporated from its alkaline aqueous solution is 1 x 10-8 M (at 532 nm excitation), for BR incorporated from its solution in DMSO, its value is also 1 x 10-8 M (at 532 and/or 633 nm excitations), and for incorporation from the solution of BR...
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New pathways to plasmonic nanoparticle assembling into 2D and 3D hybrid active systems for SERS of graphene and SERS, SERRS and GERS + SERS of aromatic molecules
Gajdošová, Veronika ; Vlčková, Blanka (advisor) ; Němec, Ivan (referee) ; Michl, Martin (referee)
In the first part of the Thesis, a new type of active system for SERS and SERRS of hydrophobic molecules, namely a 3-dimensional (3D) nanosponge aggregate with incorporated hydrophobic molecules has been developed, and tested by fullerene C60 and hydrophobic free- base tetraphenylporfine (H2TPP). The SERS and SERRS (surface enhanced /resonance/ Raman scattering) limits of detection (LODs) of C60 at four excitation wavelengths spanning the visible spectral region were found to be by one order of magnitude lower than in the reference system, which mimics the previously reported ways of utilization of Ag nanosponges as substrates for SERS and SERRS. The superiority of the newly developed sample is attributed to the efficient localization of the hydrophobic molecules into hot spots in 2D fractal aggregates of Ag nanoparticles (NPs). Diprotonation of H2TPP during the procedure using HCl as the preaggregation agent has been eliminated by employment of NaCl. On the other hand, investigation of the mechanism of H2TPP protonation during the former preparation procedure opened a possibility to employ Ag nanosponge aggregate as nanoreactor. In the second part of the Thesis, 2D assemblies of AgNPs were found to be better substrates for SERS of single layer graphene (SLG) than the 3D ones. In particular, the 2D...
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