National Repository of Grey Literature 97 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Effects of hyaluronan on properties of eye drops
Chromá, Kateřina ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
Modifying eye drops using hyaluronan leads to an increased retention time on the eye surface. Long-lasting observations of the stability of two different eye drops, Opthalmo-Septonex and Visine Classic, after the addition of hyaluronan with varying concentration are presented in this work. The interactions of hyaluronan with the eye drops, or their components benzalkonium chloride and tetryzoline, are investigated by monitoring particle sizes and the charge of the molecules. Additionally, rheological examinations of the samples are done and the mucoadhesion index is determined by using the mucine method.
Optical micromanipulation and Raman spectroscopy of cells in microfluidic systems
Klementová, Tereza ; Samek, Ota (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with optimization of analysis process and measuring antibiotics induced changes in E. coli cells via Raman spectroscopy, LTRS and microfluidic systems. Optical micromanipulation by a laser beam allows noncontact and noninvasive manipulation of objects on scale 10^-5–10^-8 m, for example bacterial cells. Microfluidic device consists of microchannels and microchambers in transparent polymer and it is used for isolation, observation and cultivation of bacterial cells. Combination of these methods gives an effective tool for observation, manipulation and analysis of microorganisms. E. coli is a microorganism potentially pathogenic for humans and faster detection of its sensitivity to antibiotic treatment would make the whole process of diagnostics and treatment easier. We performed laser tweezer-Raman spectroscopy and conventional Raman spectroscopy of bacterial cells and cells under antibiotic stress and collected Raman spectra and characteristic areas were compared with literature to establish the reliability and usefulness of this method.
Influence of particle size on microreology experiments using fluorescence correlation spectroscopy
Pavlíková, Stela ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with microrheology measured via the fluorescence correlation spectroscopy. As microrheological probes, fluorescently marked nanoparticles of 5 sizes in the range of 10-100 nm, were used. The particles had been immersed in a variety of concentrated glycerol solutions and agarose gels of different concentrations, and the FCS measurement revealed a diffusion coefficient of individual particles in each environment. Based on the coefficient, the viscosity of the glycerol needed to stop the particles could be determined. Particles of 10 nm size were not stopped even by the 100 wt% glycerol. In the case of the agarose gels, a combination of higher agarose concentration and larger particles resulted in an increase in the diffusion coefficient to an unlikely high value. This was caused probably by an agarose autofluorescence and the value indicates stopping of the particles in the given agarose gel. Later, the data acquired by the FCS measurement were converted to MSD curves using MATLAB software. The thesis discusses the influence of the experimental parameters on the shape of the MSD curve. The results showed that the number of particles and autocorrelation function have the most significant effect.
Preparation and characterization of complex liposomal for drug delivery systems
Szabová, Jana ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with the preparation and characterization of stealth liposomes and their combination with trimethylchitosan (TMC). This complex could find application in the field of inhalation administration. Stealth liposomes were prepared from neutral phophatidylcholine, negatively charged fosfatidic acid and polyethyleneglycol bounded to phosphatidylethanolamine. We have managed to prepare stealth liposomes with suitable properties that should guarantee passive targeting without evocation an immune response, despite the content of the negative component. We also found a suitable method of preparation for stealth liposome–TMC complex, where the change of size and zeta potential confirmed the non–covalent bound between two components despite the content of the polyethyleneglycol.
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
The effect of magnetic field and other selected stressors on physiology of bacterial cells
Mrázová, Kateřina ; Mravec, Filip (referee) ; Obruča, Stanislav (advisor)
This thesis deals with the effect of magnetic field and organic substances, namely benzene and p-nitrophenol, on cell of PHA producing bacteria Cupriavidus necator H16 and mutant strain Cupriavidus necator PHB4, which does not produce polyhydroxyalkanoates. Static magnetic field was generated by both permanent magnet and electromagnet. The effect of magnetic field on the growth of bacterial cells was studied using growth curves. It was found that cultivation in magnetic field and mineral medium mostly inhibits bacterial growth. Also the amount of polyhydroxyalkanoates was observed using FT-IR, flow cytometry and microscopy with fluorescent dye. Growth curves and flow cytometry were also used to study the influence of organic substances on bacterial cells. It was found that while benzene does not affect either C. necator H16 or C. necator PHB4, p-nitrophenol acts as the inhibitor of bacterial growth for both cultures. Finally the impact of p-nitrophenol on the accumulation of PHA was studied using gas chromatography.
Adhesion of (Hydro)gel Materials to the Surface – Physico-chemical Description and Biological Concequences
Žibeková, Lucia ; Mravec, Filip (referee) ; Kalina, Michal (advisor)
This Bachelor´s thesis deals with study of adhesion of hydrogels materials to the surface. Three biopolymers were selected for this purpose, one of which is psychically cross-linked (agarose) and two are chemically cross-linked (based on sodium alginate cross-linked with Ca2+ and polyvinyl alcohol cross-linked with borax). In the experimental part of the work, adhesion was first examined by a visual method on an inclined plane. The tilt was at different angles (30°, 45°, 90°) where it was observed whether the hydrogel was able to attach to a solid surface or slip down. The agarose was examined in different concentrations from 0.5 wt% to 4 wt% in both methods. Also, the alginate gel was examined at various concentrations with two different cross-linked agent. However, alginate was only used in the visual method because of its inhomogeneity. In contrast, the PVA gel was examined at 10:1 and 4:1 ratios for the both methods. The second method in the experimental part was the tensile test carried out on the Inova apparatus – hydraulic pulsator, and thus the methodology for the study of physical and chemically cross-linked hydrogels was optimized. With increasing concentration of agarose gels, adhesion strength and work increased as well. For PVA gels, the adhesion work was higher, but the adhesive strength remained approximately the same as for the agarose gels.
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.
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.
Correlation between steady-state fluorescence anisotropy measurement on fluorimeter and fluorescence microscope
Obrusníková, Lenka ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This Work concentrates on detection fluorescent anisotropy on a model system of fluorescent probe and glycerol. In this thesis, the ATTO 488 was used as a fluorescent substance and glycerol solutions of different concentrations were used to simulate different viscous environments. A fluorescence spectrofluorometer and confocal fluorescence microscope were used for the measurements. A linear encrease anisotropy with increasing viscosity of the environment was observed on fluorometer. The same trend was detected on fluorescence microscope. The values were compared and correlation factors were determined. The accuracy of the measurement was verified by calculations using the Perrin´s equation.

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