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Hydrogels with incorporated vesicular systems
Kalendová, Lucie ; Pekař, Miloslav (referee) ; Venerová, Tereza (advisor)
This bachelor thesis deals with the incorporation of vesicular systems into polysaccharide – based hydrogels. The chosen vesicular systems were Ion Pair Amphiphile vesicles (IPA), which consist of cetrimethylammonium bromide, sodium dodecyl sulfate, dioctadecyldimethylammonium chloride and cholesterol. The work is divided into two parts. In the first part, interactions between IPA vesicles and sodium hyaluronan and interactions between IPA vesicles and sodium polystyrene sulfonate were studied. Even though interactions occured, it was not possible to prepare a hydrogel based on these interactions. The second part of this work deals with incorporation of IPA vesicles into an agarose – based gel when heated. Particles of two different concentrations (1 mmol·l1 and 2 mmol·l1) were used. The effect of the IPA particles on the properties of the gel was observed with rheological measurements. The results showed that the gel with incorporated particles has a longer linear viscoelastic region and that there were no interactions between the IPA particles and the gel. The particles only fill the gaps of the gel network. Different behaviour within the gels with different concentrations of IPA vesicles was not observed.
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Interactions and aggregation in hyaluronan-aminoacid-surfactant systems
Venerová, Tereza ; Velebný, Vladimír (referee) ; Pekař, Miloslav (advisor)
The effect of native hyaluronan addition on CMC of excluded surfactants (Tween 20, BETADET THC 2, SDS, CTAT a CTAB) in physiological solution (0,15 M NaCl) has been investigated by fluoresence spectroscopy with Pyrene and Nile red as probes. The greatest influence on CMC has been observed in systems with cationic surfactant. System of cetyltrimethylamonnium bromid has been closely studied. Solubilization experiments with a hydrophobic dye Sudan red has been realized and aggregation number of this system has been determinated via fluorescence quenching with cetylpyridinium chloride as quencher and Pyrene as fluorescence probe. Addition of hyaluronan (native or hydrophobicaly modified) reduces aggregation number of system.
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Characterization of microfludic chips
Vejrosta, Jakub ; Enev, Vojtěch (referee) ; Venerová, Tereza (advisor)
Nowadays, when we are moving to smaller and smaller scales, microfluidics is being used, which helps us to move from fluid devices to the dimensions of microfluidics, which may have a great application in the future. This work deals with the correct preparation and production of a microfluidic chip. Which consist of two parts. One part is the polydimethylsiloxane (PDMS) part of the chip, and the other is the coverslip. In this work, the production process of this chip is improved. The functionality of these chips and the time dependence of the age of the chip and the polydimethylsiloxane from which the chips are made were tested using fluorescence microscopy.
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Inverse FCS in colloidal systems research
Richterová, Veronika ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This diploma thesis is focused on the study of inverse fluorescence correlation spectroscopy, especially with the regard for the usage of different fluorescent probes and different sized analysed particles. At first, the proper concentration of fluorescent probes was determined. In this concentration is the probe considered as a medium surrounding the analysed particles. Based on this concentration, which was determined as 400 M, several sets of samples were prepared. This samples contained different concentration of polystyrene particles of 100 and 500 nm diameter and multilamellar liposomes. Then, the FCS curves of samples with different fluorescent probes were measured. Fluorescein, rhodamine 6G and Atto 488 were used as fluorescent probes. As a result from experiments, it was found, that particles with 100 nm diameter cannot be analysed with none of the fluorescent probes. Inverse FCS method can be applied to systems, that contains particles with 500 nm diameter and fluorescein. Systems with rhodamine 6G have the same behaviour as typical FCS measurement. It is caused by dimerization of this probe and it cannot be used for 500 nm particles. Liposome samples can be established with iFCS method, but the results are biased by random distribution of liposomes size.
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Behaviour of hydrophilic fluorescent probe Oregon Green 488 in hydrogel environment
Lacko, Kata ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
The aim of this bachelor’s thesis is to study the behavior of a hydrophilic fluorescent probe named Oregon Green 488 in hydrogel environment. The hydrogel was created using sodium hyaluronan and CTAB (cetyl trimethylammonium bromide) as a cationic surfactant. Solution of 0.15 M NaCl was used as a solvent, which provides physiologic conditions in the sample. The behavior of the fluorescent probe was characterized by steady-state and time-resolved fluorescent measurements. To obtain the emission spectra of the probe and to find the emission maximum the method named TRES (time-resolved emission spectra) was used. Fluorescence intensity decay measurements as a function of wavelengths allowed to create deconvolution of the emission spectra, which provided information about the fluorescent lifetime and the probe’s states’ relative representation in the solution. Hydrogels were examined 5 days and 1 month after the preparation and the results were compared. Oregon Green 488 demonstrated one fluorescent lifetime in the hydrogel environment in the range, 4,14,45 nm in the fresh hydrogel and 4,14,6 nm in the stable hydrogel. The emission maximum was obtained at 525 nm in both cases. The fluorescent probe’s behavior in the hydrogel environment is stable, presumably there are no interactions occurring between the hydrogel and the probe. Furthermore, no interactions were recorded between the probe and hyaluronan.
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Polysaccharide gels in medical applications
Svitačová, Denisa ; Kadlec, Martin (referee) ; Venerová, Tereza (advisor)
This bachelor thesis deals with the performance of hydrogels containing polysaccharides, their characterization and reproducibility of the preparation of these gels, which is described in the literature. Based on the research, suitable polysaccharides, namely guar and gellan gum, were selected. Subsequently, an article was selected, the procedure of which was reproduced. Calcium chloride was used as a crosslink agent in the mixture of guar gum and gellan solution. Problems appear in the reproducibility of the article which did not allow the exact repetition of the hydrogel preparation procedure described in the article. Based on the findings, an optimized range of mixtures with various other gelling agents was developed. The individual prepared materials were suitably characterized by rheological tests. Specifically, amplitude tests, the results of which proved the formation of a three-dimensional network in their structure, and thus the formation of hydrogels. Frequency tests were used to determine their mechanical properties.
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Hyaluronan-CTAT hydrogels
Velcer, Tomáš ; Venerová, Tereza (referee) ; Pekař, Miloslav (advisor)
This thesis studies the properties and behaviour of phase-separated hydrogels prepared by interaction of hyaluronan with oppositely charged surfactants. Three representatives of surfactants, namely cetyltrimethylammonium bromide, chloride and p-toluensulfonate (CTAB, CTAC, CTAT), were selected for comparison. Using the method of rheology, the fact that the system of Hya-CTAT forms the most rigid hydrogels has been proved. Higher molecular weight of hyaluronan has also direct influence on the volume and stiffness of the newly formed hydrogels. Preparation methods were compared as well. Mixing the stock solutions of entry components appeard to be the most suitable. Small-angle X-ray scattering was used for determination of shape and size of surfactant's micelles, concluding that it has no effect on the volume of formed gels. The results of this study indicate that given gels are to a certain extent competitive and incorporation of hyaluronan into their structure is desirable with respect to its biological activity. This offers a potential usage of these substances in the field of medical applications.
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Advanced microscopy in the research of colloidal systems
Valovič, Stela ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
This bachelor thesis is focused on dual-colour fluorescence cross-correlation spectroscopy. As a suitable combinations of fluorescenct dyes were designated this combinations: perylene + nile red, perylene + DiD and DiO + DiD. The funtionality of this method was veried by tetraspeck. The experiment of FCCS was performed on micellar surfactants solitions which proved to be unsuitable for this method. Consequently, liposomes with DiD and DiO incorporated in phospholipid bilayer were measured. The cross-correlation in liposomes was succesfuly measured.
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Study of microviscosity of membrane systems based on ionic amphiphilic pairs
Moslerová, Lenka ; Venerová, Tereza (referee) ; Mravec, Filip (advisor)
In this master ‘s thesis, catanionic vesicles formed by the pseudo-double-chain complex CTA – DS were investigated from the point of view of microviscosity. Samplesand of cationic vesicles contained 23, 43 and 53 mol. % of cholesterol and the double-chain surfactant DODAC. Cationic vesicles were prepared for visual observation, their stability was determined by DLS and the prepared system was further investigated. Microviscosity was determined from fluorescence anisotropy. To study the outer part of the membrane, laurdan fluorescent probes were used whereas diphenylhexatriene was used for the inner part of the membrane. This method has been proven to be suitable because it reflects the conditions of the membrane. Moreover, a 1,3-bispyrenylpropane probe forming intramolecular excimers was used to study the microviscosity in the vesicle bilayer. The dicyanovinyljulolidine (DCVJ) probe was applied in the case of the molecular rotor technique. It has been shown that in the case of the DCVJ probe, the molecular rotor technique is practically unusable, due to the fact that the probe has a low quantum yield at low temperatures. Also, the excimer formation of P3P probes does not lead to the expected results. The cationic vesicles do not seem to support this formation, as they are too closely related. This type of probe can be used for the selected system with some restrictions.
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Hydrogels with incorporated proteins
Uhrínová, Alžbeta ; Mravec, Filip (referee) ; Venerová, Tereza (advisor)
This work deals with associative peptides. The aim was to characterize a given associative protein and perform experiments leading to the creation of a hydrogel system containing the selected protein. Casein solutions were initially prepared to determine micellar concentration (CMC) using a pyrene fluorescence probe. Subsequently, the micelles were characterized by dynamic light scattering (DLS) and their size, zeta potential and also the effect of temperature on these properties were determined. Based on the characterization of the particles at temperature, suitable gels were selected into which the protein particles were subsequently incorporated.
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