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The influence of detergents on time to failure of high density polyethylene by full notch creep test performed in corrosive bath
Kotoučková, Simona ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
The thesis deals with the study of the influence of concentration and different types of surfactants (Igepal CO-520, Arkopal N110, Igepal CO-890, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, dodecyltrimethylammonium bromide and Dehyton PL) on the environmental stress cracking resistance of high-density polyethylene by means of Full Notch Creep Test. Furthermore, the influence of ligamental stress (3,5; 4,0 a 4,5 MPa), pH of the prepared active environment and type of the water used as a solvent for the surfactants on the time to failure was monitored. An accelerating effect was observed at increased concentration, stress and molecular weight. Faster failure was achieved after exposure to ionic types compared to nonionic. The rate of the notch opening was determined. The brittle and ductile behavior during the process of failure was evaluated by microscopic analysis of the morphology of the fracture surfaces. Based on the pH change after the test, the stability of the active environment was evaluated. Deteriorating quality of surfactant solutions was observed. Raman spectroscopy and Fourier transform infrared spectroscopy were used to detect the surfactant on the surface of the test specimen after the test.
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Interactions between Hyaluronan and Surface Active Substances
Krouská, Jitka ; Burgert,, Ladislav (referee) ; Lehocký,, Marián (referee) ; Vikegard,, Peter (referee) ; Pekař, Miloslav (advisor)
Vliv hyaluronanu na micelizaci tenzidů byl studován různými fyzikálně-chemickými metodami. Byly zvoleny dva kationaktivní tenzidy, a to tetradecyltrimethylammonium bromid (TTAB) a cetyltrimethylammonium bromid (CTAB). Metoda izotermické titrační kalorimetrie byla využita pro stanovení entalpie micelizace, tenziometrie popisuje povrchové vlastnosti daných vzorků. Byl sledován také vliv různé molekulové hmotnosti použitého hyaluronanu a délka alkylového řetězce tenzidu na agregační chování daného systému. Výsledkem jsou hodnoty kritické micelární nebo agregační koncentrace tenzidu. V neposlední řadě se diskutuje využití agregátů hyaluronan-tenzid jako možné nosiče pro cílenou distribuci léčiv.
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Microcalorimetric study of interactions between hyaluronan and catanionic vesicular systems
Mach, Jakub ; Pekař, Miloslav (referee) ; Krouská, Jitka (advisor)
Properties of surfactants in water, interactions between oppositely charged surfactants and interactions in system containing didecyldimethylammonium chloride (DDAC), hyaluronan and ion pair amphiphile (IPA) have been studied using isothermal titration calorimetry. For the study of properties of surfactants in water and their mutual interactions, two cationic surfactants have been chosen, namely cetyl trimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex), and an anionic surfactant sodium dodecyl sulfate (SDS). For hyaluronan, a molecular weight of 250 450 has been chosen. Critical micelle concentration of the chosen surfactants and enthalpy of the investigated interactions have been determined using the TAM III calorimeter. To prove the interactions in system containing hyaluronan, DDAC and IPA and to determine enthalpy the Microcal PEAQ-ITC calorimeter has been used.
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Utilization of biosurfactants for incorporation of hydrophobic domains into modern controlled-release systems
Nešpor, Tomáš ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This work deals with the current topic of carrier systems. Since the biggest problem is the passage of hydrophobic drugs through the bloodstream, or through universal body barriers (eg blood-brain), it is necessary to chemically modify these carriers in order to be able to administer hydrophobic substances effectively. Based on a literature search, several systems are designed and subsequently studied, in which there is a presumption of possible use for carrier systems and at the same time they have biosurfactants incorporated in them due to their ability to solubilize hydrophobic molecules. The theoretical part of this work will describe the individual biosurfactants, the process of their production, their physicochemical properties, and the possibility of their use in carrier systems. At the same time, the individual carrier systems, the procedure of their preparation, the possibilities of their use are described, and their advantages and disadvantages are also compared. In the practical part, the screening of both individual substances and their mutual interactions, as well as methods used to study the emerging structures is then performed. The study of molecular interactions is primarily performed using the technique of dynamic light scattering. The next part describes the optimization of hydrogel formation with incorporated biosurfactants in their structure and then the formed gels are subjected to rheological and solubilization tests. The study of the internal structure of these gels is performed using a scanning electron microscope.
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Utilization of methods of physicochemical and structural analysis in characterization of biosurfactants
Nešpor, Tomáš ; Hurčíková, Andrea (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the very actual topic of biosurfactants. In the theoretical part of the thesis, a literature review on this topic was carried out and on the basis of this research, physicochemical and structural analysis techniques suitable for testing these substances were selected. In the practical part, the model biosurfactants were first characterized by standard methods used to study these compounds. Fourier transform infrared spectrometry was chosen as a standard technique of structural analysis. As an example of a universal technique for the study of aggregation behavior was used tensiometry. In the next part of the thesis there were designed and optimized alternative techniques usable for fast and inexpensive physicochemical analysis of these substances. It was mainly a microplate assay and its modified alternatives. Thus, the methods of low sample consumption, but also effective in confirming the presence and a possible amount determination of the biosurfactant content in the solution. The result of this work is a few simple methods that have been proven effective in studying biosurfactants.
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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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Drugs Loading in Thermosensitive Micellar Gels
Smolková, Miroslava ; Pavliňáková, Veronika (referee) ; Chamradová, Ivana (advisor)
Presented diploma thesis deals with drug encapsulation of Sulfathiazole (STA) in thermosensitive hydrogel composed of amphiphilic fibrous molecules of copolymer poly(D,L-lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA). In the experimental part, the structure of the micelles which is dependent on the concentration of the default copolymer, was thoroughly described. The method of dynamic light scattering (DLS) was used to dimensionally characterize the micellar size in aqueous solution. At the same time, the Cryo-Transmission Electron Microscopy (Cryo-TEM) imaging technique confirmed the transition from spherical micelles to fibrous branched structures with a number of topological interactions. The change in viscoelastic properties of micellar hydrogel after addition of STA was studied by rheological analysis. The studied triblock copolymer appears to be a suitable tissue engineering material as a carrier in applications for targeted drug delivery and tissue regeneration.
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Key factors of selected tensides used for full notch creep test of high density polyethylene
Křivánková, Eliška ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
The thesis deals with the study of surface-active properties, zeta potential, particle size and adhesion of surfactants (Arkopal N110, Igepal CO-520, Igepal CO-890, Dehyton PL, sodium dodecyl sulfate and dodecyltrimethylammonium bromide) selected for full notch creep test method. To determine the surface phenomena occuring in a solution due to their presence at 25, 50 and 80 °C, the Du Noüy ring method of surface tension measurement was used. The importance of factors such as concentration, ionic character and the molecular structure of the surfactants, temperature and dispersion media (pH, purity) were analysed. Dynamic light scattering measurements were performed in order to evaluate the particle size and the electrophoresis method was used to determine the zeta potential. The results were compared to the contact angle measurements, i. e. adhesion tendency between surfactant solutions and the surface of selected types of high density polyethylene. The optical analysis was used to evaluate the contact angle. The negative impact of water purity was negated. The temperature dependecy was specific for each of the examined surfactant species, however the relationship between temperature and the length of hydrophilic chain was discovered. Alkaline pH was less convenient for amphoteric surfactant than acid or neutral environment, but this might have been caused by components contained in the buffer. The character of surfactant solutions was mostly monodisperse. The only exceptions were 1mM Igepal CO-520 and 3mM Dehyton PL. Further investigation led to conclusion that the molecules tend to form agglomerates. Adhesion was in accordance with surfactant effectiveness of surface reduction and adsorption. However, this theory did not match the data obtained from testing acid and neutral Dehyton PL solutions' adhering to polyethylene species containing carbon black.
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Study of interactions of the surfactant component of Septonex with selected proteins
Bohunská, Miroslava ; Pekař, Miloslav (referee) ; Krouská, Jitka (advisor)
The study of protein and surfactant interactions is of great significance in a number of applications, such as the cosmetic, food or pharmaceutical industries and many others. However, they require further study due to their compositional complexity and the limitations of current analytical approaches. In this thesis, the cationic surfactant septonex in combination with two differently charged proteins lysozyme and bovine serum albumin under different physiological conditions (temperature, surfactant concentration, environment and others) was selected to study the interactions. Characterization of protein-surfactant interactions is a very important but challenging task, therefore it is essential to use appropriate approaches to explore the nature of these interactions. In order to unify the information to provide rational models, calorimetric methods (DSC, ITC) and dynamic light scattering were used. Isothermal titration calorimetry monitors the evidence for the formation of the system of the mentioned substances and information on aggregation behavior, differential scanning calorimetry characterizes the thermal stability of proteins and dynamic light scattering made it possible to monitor changes in particle size. Both proteins have been proven to interact with positive septonex, even if the lysozyme molecule is also positively charged. However, significant differences were found between the two proteins. From the obtained results it is evident that the identical charge of the protein with the surfactant has an effect on the intensity of the measurement, although all measured interactions showed an endothermic character.
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Fluorescence quenching in study of aggregation behavior of colloids
Srholcová, Barbora ; Hrdina,, Radim (referee) ; Pekař, Miloslav (advisor)
This work focuses on examination of hyaluronan-sulfactant aggregates in term of determination of aggregate number. The value of critical micellar concentration (CMC) cetyltrimethylammonium bromide (CTAB) in three different solvents (water, phosphate buffer and physiological solution). Next the effect of the native hyaluronan supplement on the value of CMC was examined. It wasfound out that the solvent has the biggest effect on the value of CMC whilst the hyaluronan supplement affects CMC only a little. The aggregate number (Nagg) CTAB and the effect of the native hyaluronan supplement were determined out by means of fluorescence quenching. Pyrene was used as a fluorescence probe. Iodine and cetylpyridinium chloride (CPC) were used as quenchers. Sulfactant was dissolved in three different solvents (water, phosphate buffer and physiological solution). Not only the hyaluronan supplement but also the used solvent has the strong effect on the value of the aggregate number. When using 10mM CTAB dissolved in physiological solution the value of Nagg was 119 ± 4 while the value was half in buffer. Then we found out that in most cases the hyaluronan supplement reduces the value of the aggregate number.
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