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Microrheology in colloid systems
Hradecká, Lucie ; Burgert, Ladislav (referee) ; Mravec, Filip (advisor)
This master thesis is focused on the evaluation of the influence of particle surface properties on the results of microrheological measurements with biopolymer solutions. Hyaluronan has been chosen as negatively charged polymer, chitosan as positively charged polymer and glycerol and its solutions of various concentrations were used as homogenous model systems. Dynamic light scattering and single particle tracking microrheology were chosen from passive microrheological techniques. Particles with various surface modifications (neutral, positive surface charge and negative surface charge) were used for the experiments. The results of microrheological techniques were then compared with classic rheology and moreover the glycerol results were compared with tabulated values.
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Biomolecules influence on optical properties of deposited quantum dots
Roček, Vojtěch ; Mravec, Filip (referee) ; Drbohlavová, Jana (advisor)
This thesis is focused on creation of quantum dots of titanium dioxide with help of nanoporous alumina mask and on funcionalization of their surface in purpose to increase the quantum yield of its. This thesis is devided into 6 main chapters, where the glossary topic of quantum dots creation process and ways of practical usage of these quantum dots are made. The theoretical knowledge is used for creation of titanium dioxide quantum dots, which was deposited by gold and funcionalized with glutation. The results are shown and discussed in the end of this work.
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Advanced membrane systems
Gjevik, Alžběta ; Márová, Ivana (referee) ; Mravec, Filip (advisor)
The diploma thesis deals with cellular membrane model preparation on microfluidic devices. It summarizes means of microfluidic device fabrication, phospholipid bilayer formation mechanisms, optimization techniques and characterization methods of those systems. It focuses on free-standing planar lipid bilayers which are easily accessible by a number of different characterization methods and at the same time exhibit good stability and variability. The aim of this work is to design and prepare a microfluidic chip on which a planar lipid bilayer can be prepared. It therefore presents microfluidic device prepared by soft lithography of PDMS adapted for model membrane formation by self-assembly of phospholipids at the interface of aqueous and organic phases created by the architecture of the microfluidic device. Formation of the model membrane was visualized by optical microscopy and fluorescence-lifetime imaging microscopy.
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Time-resolved fluorescence in investigation of colloid system
Černá, Ladislava ; Ouzzane, Imad (referee) ; Mravec, Filip (advisor)
This thesis is focused on determination of the basic spectral characteristics, such as fluorescence maximum and lifetime, of fluorescent probes prodan [6-propionyl-2-(dimethylamino)naphthalene] and perylene by steady-state and time-resolved fluorescence spectroscopy. Time-resolved measurements were realized through TCSPC method (time-correlated single photon counting). The characteristics of prodan were found in water, acetone, n-heptane and in mixtures of these, so that a polar scale of environments would arise. Both of the mentioned probes were further investigated in systems of aqueous solutions of hyaluronic acid (300 kDa) at the concentration of 10 mg•l-1 together with cationic surfactant CTAB (cetyltrimethylammonium bromide) at the concentration range from 0.01 to 0.20 mmol•l-1 (before CMC). The aim was to confirm the reach and the range of critical aggregation concentration of the surfactant (CAC), to uncover the basic spectral characteristics of the mentioned probes in this concentration range and to verify the stability of this system in the presence of NaCl at the concentration of 0.15 mol•l-1. Furthermore, by TCSPC method were obtained time-resolved emission spectra of prodan from the system of hyaluronic acid and CTAB at one concentration of CTAB in CAC interval both without salt and with salt at the concentration of 0.15 mol•l-1. The obtained time-resolved emission spectra correlated with the results of the CAC concentration range measurement. After addition of salt the system of CAC proved to be unstable.
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Use of fluorescent techniques in study of aerosol deposition
Lippay, Josef ; Jedelský, Jan (referee) ; Mravec, Filip (advisor)
Several experiments were designed for utilization of fluorescence spectroscopy as a method of aerosol particle detection in a model of lungs. One of the experiments was to arranged use luminescent properties of DEHS (bis(2-ethylhexyl)decandioate) for calculating aerosol deposition. The outcome of this experiment was confirmation of clusters existence, which causes luminescence of DEHS. But the luminescence is not enough dependent on concentration and as such is not suitable for calculation of aerosol deposition. As the next experiment DEHS-fluorescein particles were generated by condensation monodisperse aerosol generator (CMAG), where water was used instead of isopropyl alcohol as a solvent. By this alteration the negative influence of DEHS was eliminated, which caused results refinements of aerosol deposition. Generation of fluorescein sodium salt particles by small-scale powder disperser (SSPD) was designed as a last experiment. The lower deposition efficiency measured by this method was caused by particles polydispersion. Photo records were used for documentation of Hot-spots. Outcomes of this study are new knowledge of fluorescence spectroscopy utilization for study of aerosol deposition and possibilities of fluorescent aerosol particles generation. Acquired data can serve for knowledge extension of possible detection methods for aerosol particles in the model of lung and can serve for validation of numerical simulations.
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Fluorescence probes in investigation of associative colloid domains.
Mischingerová, Monika ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
The aim of this thesis was to determine how the concentration of the fluorescent probe (pyrene) affects the critical micelle concentration. In this thesis were used all types of surfactants (anionic, cationic and nonionic). As representatives of the anionic surfactants were chosen sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfate (SDBS), as the cationic surfactant was chosen cetyltrimethylamonium bromide (CTAB) and as the nonionic polyoxyethylene(9.5)octylphenol (Triton X–100). The critical micelle concentration of these surfactants were measured with a pyrene at three different concentrations. All data obtained by fluorescence spectroscopy were fitted by a Boltzmann-type sigmoid. It was found out that in the case of the anionic surfactants there is some correlation between the critical micelle concentration of the surfactant and the concentration of the fluorescent probe. In both cases (SDS, SDBS) the value of the critical micelle concentration increased with increasing concentration of the fluorescent probe. For the other surfactants (cationic and nonionic) was observed no change in the critical micelle concentration values depending on the concentration of pyrene.
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Fluorescence probes to study the properties of hydrogel systems
Máčala, Jakub ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This bachelors thesis is focused on possibility of selected fluorescent probes for study of properties of hydrogel systems. Chosen probes are Prodan for polarity study, HPTS for measurement of pH of the probe environment and platinum complex [2,6-Bis(2-pyridyl)fenyl-C,N,N]chloroplatinum(II) for its unique fluorescence properties and potential of energy transfer studies in hydrogel systems. Spectral properties of fluorophores were defined in selected set of solvents with different polarity with steady state fluorescence spectroscopy method. Properties of HPTS probe were also tested in buffers with different pH. Subsequently, hydrogels based on hyaluronan-septonex and dextran-SDS with incorporated fluorescence probes were prepared. Steady state fluorescence measurement of fluorophores from hydrogel were made using fluorimeter optical fibres. It was found, that probes Prodan and HPTS are suitable for study of polarity and pH of hydrogels and probably they will be able to be used for study of hydrogel with other techniques, like fluorescence microscopy, however platinum complex is, due to the low fluorescence intensity and possible quenching by polar water environment, probably not suitable for other measurements.
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Phase separation in dilute solutions of polymers and surfactants
Klementová, Tereza ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor's thesis deals with conditions of phase separation in system of polyelectrolyte (sodium hyaluronate) and cationic surfactant (cetyltrimethylammonium bromide). Separated phase was studied by fluorescence measurement with Nile red as a fluorescence probe and there were also specified rheological properties using flow tests and frequency oscillatory tests. Behaviour of separated microgel was also observed in solution of NaCl.
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Hydrogels based on microemulsions and polyelectrolytes
Růžičková, Kristýna ; Kalina, Michal (referee) ; Mravec, Filip (advisor)
This bachelor thesis deals with preparation and characterization of microemulsion based phase separated hydrogels while using low molecular weight and high molecular weight hyaluronan. Microemulsions were prepared from canola oil, sunflower oil, lemon oil and tea tree oil. As a dye for studies of behaviour of hydrogels was used Oil red O which simulates hydrophobic drug. The main part of this thesis studies the release of this dye from hydrogels by using UV-VIS spectroscopy. The content of the dye in hydrogels was monitored after 24, 48 and 72 hours. Based on measured data we can state that hydrogel prepared from low molecular weight hyaluronan release bigger amount of the dye than hydrogel from high molecular weight hyaluronan. Based on measured data after 72 hours we can say that hydrogel from microemulsion with tea tree oil and hydrogel from microemulsion with lemon oil released bigger amount of the dye than hydrogel without microemulsion. Another advantage of these two hydrogels is increased thougness. Content of sunflower and canola oil indicated rather negative influence on behaviour of hydrogels.
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Study of UV-generated fluorescent zinc complexes by fluorescence spectroscopy
Havlíková, Martina ; Vaculovičová, Markéta (referee) ; Mravec, Filip (advisor)
This thesis focuses on the study of UV light-generated zinc complexes with cadmium and organic molecules SAM, SAH, CYS, HCYS and GSSG, specifically at 375 nm. Furthemore, the aim of the work is to characterize the precursors spectrally and temporally before and after irradiation in the transilluminator at 250 nm. Study of genesis these complexes was performed by FLIM. Thanks to this method, it was found that the formation of complexes occurs only with Zn:SAH, Zn:GSSG and Zn:Cd. The formation of complexes is influenced by the method of preparation. The spectral characteristic was performed on a fluorimeter where the increase in fluorescence intensity of the irradiated solution with the precursors was expected. These were turbid solutions where sedimentation of the particles was observed and the intensity of fluorescence was changed. In the Zn:SAM and Zn:CYS sample, the sedimentation increased in intensity, while in Zn:SAH and Zn:HCYS decreased. The Zn:Cd precursor solution was clear and there was no change in intensity. Zn:Cd showed the best spectral properties, while the Zn:SAM sample, whose excitation and emission maxima are very close to each other, appeared to be the worst. A sample with Zn:CYS and Zn:HCYS showed almost the same spectra and respective peak results. Based on lifetime characteristics by TCSPC, the sample with Zn:CYS, Zn:HCYS and Zn:GSSG, which showed 3 lifetimes, was best treated. Lifetime could not be unambiguously determined for SAM and SAH samples. Zn:Cd had 4 lifetimes
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