|
|
Luminescent nanoparticles for 3D imaging
Smolka, Rastislav ; Mravec, Filip (referee) ; Vala, Martin (advisor)
The aim of this diploma thesis is to study the optical properties of new -conjugated molecules based on 1,4-di(4'-N, N-diphenylaminostyryl)benzene and their potential application in advanced imaging techniques of biological specimens, the so-called multiphoton microscopy. The thesis focuses mainly on the characterization of their optical properties and the determination of their two-photon absorption cross-section using a unique laser equipment. Furthermore, a suitable methodology for the preparation of nanoparticles from these molecules, their characterization and stability are also developed. The thesis also investigates the influence of structure on the optical properties of these molecules. The relation between the length of the conjugated system and the presence of substituents on the backbone has been shown for the optical properties of the molecules in the solvent, the position and shape of the two-photon absorption spectrum and the value of two-photon absorption cross-section. It has been shown that this substance retains its unique fluorescent properties even in the form of nanoparticles and therefore appears to be a suitable candidate for the observation of biological specimens using multiphoton fluorescence microscopy. The work contributes to the knowledge base for the design of the chemical structure of molecules with desired properties.
|
|
|
Interaction of trimethylchitosan with Niaproof surfactant
Zbořilová, Hana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This thesis is focused on the study of interaction of the polycation N,N,N-trimethylchitosan (TMC) with the anionic surfactant Niaproof® 4 in water and physiological saline solution. Due to the commercial unavailability of N,N,N-trimethylchitosan, the polymer was first synthesized from chitosan, followed by NMR and FTIR characterization. Before the study of the system polycation–anionic surfactant itself, the behavior of the anionic surfactant Niaproof® 4 in aqueous solution and physiological saline solution was explored. The micellization of the surfactant Niaproof® 4 and the aggregation of TMC–Niaproof® 4 system were observed by fluorescence spectroscopy using the fluorescence probe pyrene. Values of critical micelle and critical aggregation concentration were determined on the basis of measurements. It was confirmed that presence of the sodium chloride supports the micellization by increasing the ionic strength of the solution, which leads to decrease of CMC in physiological saline solution. The interaction of TMC–Niaproof® 4 occurs at lower concentration then CMC in both aqueous and physiological environments. Phase separation occurs at higher concentrations of the surfactant leading to stabilization of the system.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
guest ::
