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Diffusion of organic molecules in the hydrogel environment
Holubová, Anna ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with study of hydrogels formed by phase separation of hyaluronan with oppositely charged surfactants cetyltrimethylammonium bromide (CTAB) and Septonex. It follows the bachelor thesis and extends the knowledge about the detailed characterisation of the inner environment of the hydrogel by determining the diffusion behaviour of the fluorescent probes Atto 488 and Nile Red using fluorescence correlation spectroscopy (FCS) technique and its modified version dual-focus fluorescence correlation spectroscopy (2f-FCS). Compared results showed that both methods show similar values and probes specifically interact with CTAB but Atto 488 shows only weak interaction with Septonex compared to Nile Red. Additionally, these interactions were not affected by the molecular weight of hyaluronan. In conclusion, it was recommended to measure this type of hydrogel in a small depth of gel using a conventional method.
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Monitoring of the influence of selected synthetic preservatives on the stability of cosmetic emulsions O/W
Holubová, Anna ; Vítová, Eva (referee) ; Zemanová, Jana (advisor)
This bachelor’s thesis collects available information on commercially supplied cosmetic preservatives Sensiva PA 20 (ingredients by INCI: phenethyl alcohol, ethylhexylglycerin), Euxyl K 900 (ingredients by INCI: benzyl alcohol, ethylhexylglycerin, tocopherol) and Euxyl PE 9010 (ingredients by INCI: phenoxyethanol, ethylhexylglycerin) from German company Schülke & Mayr, especially with regard to the assessment of their potential influence on the stability of cosmetic emulsion O/W. Subsequently, based on the literature review, selected methods were applied, their combination may prospectively serves to required evaluation of the influence on the stability of studied preservation systems.
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Using diffusion techniques in the study of hydrogels
Holubová, Anna ; Žitňan, Michal (referee) ; Mravec, Filip (advisor)
Properties of colloidal systems, especially hydrogels, were studied using the method of fluorescence correlation spectroscopy (FCS). Hydrogels were prepared based on hyaluronan and cationic surfactant CTAB interactions. The proposed hydrophilic fluorescent probe, suitable for the study of phase-separated hydrogels in polymer-surfactant systems, was chosen ATTO 488 due to the suppression of triplet state. As a hydrophobic probe was chosen Nile Red. Individually were examined micellar systems of 10 mM CTAB and 0,5% sodium hyaluronate in water and 0,15 M NaCl in different concentrations of selected fluorescent probes. Subsequently the hydrogel systems were studied. The results showed that the measurement of hydrogels by this method is realizable. Short lifetimes were created by a complex probe and CTAB causing quenching and low levels of diffusion coefficients characterize the viscous environment of study system.
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