|
|
Optimization of condition of procedure of gelation hydroxyethylcellulose using citric acid
Burešová, Natálie ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The bachelor thesis dealt with hydrogels, which have the advantage detention large quantities of water, it allows large potential applications, such as in medicine. Hyaluronan and hydroxyethylcellulose were the reactants of crosslinking reaction. Citric acid was crosslinking agent which is nontoxic and inexpensive. Hydroxyethylcellulose and hyaluronan for crosslinking reaction were selected on the finding from available publications. The resulting gels can be used mainly in medicine because they are nontoxic. The main aim of the thesis was optimalizacion process of gelation and hydroxyethylcellulose and finding a suitable gelation process. Selected gelation procedure is applied to a mixture of hydroxyethyl cellulose and hyaluronan in two different weight ratios and hyaluronan. Chemicaly cross-linked were considered samples, which contained hydroxyethylcellulose and then a mixture of hyaluronate and hydroxyethyl cellulose in a weight ratio of 3:7.
|
|
|
Microcalorimetric and Light Scattering Methods in the Study of Interactions in Biopolymer - Surfactant System
Šojdrová, Kamila ; Mravec, Filip (referee) ; Krouská, Jitka (advisor)
Biopolymer surfactant systems have been studied by using different physico chemical methods. As the biopolymer, it was chosen high (1400–1600 kDa), medium (250–450 kDa) and low (8–15 kDa) molecular weight sodium hyaluronate. Two cationic surfactants – cetyltrimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex) were selected to provide polyelectrolyte complexes with oppositely charged hyaluronan. The critical aggregation concentration of the surfactant in the system was monitored by dynamic light scattering (Zetasizer Nano ZS). SEC-MALS method was used for the description of the conformation of sodium hyaluronate of different molecular weights and polyelectrolytes complexes hyaluronan surfactant after reaching the aggregation point. Isothermal titration calorimetry (ITC) was used to determine the critical aggregation concentration of the surfactant by monitoring the thermal changes accompanying the aggregation of the system. It was found out that the increasing molecular weight of hyaluronan in these systems decreases the critical aggregation concentrations and conversely.
|
|
|
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.
|
|
|
Releasing of the solubilized substances from the phase-separated hydrogels
Havlíková, Martina ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This bachelor thesis is focused on releasing of the solubilized substances from the phase separeted hydrogels. The aim of this work is to determine the solubilization capacity of these hydrogels. Preparation of them were based on interaction between hyaluronan and cationic surfactant carbethopendecinium bromide. Hydrogels were prepared by two possible ways, „wet“ and „dry way“. For solubilization experiments were used fluorescein and acridine orange as fluorescent probes. Primarily UV-VIS spectrophotometry was used to determine if these probes are released form hydrogel or not. Hydrogels were monitored after 24, 48 and 72 hours from their preparation. But this method proved to be inappropriate and inaccurate, because of cloudy supernatants over the hydrogels and also because of very low concentrations of fluorescent probe in this solution. For these reasons instead of this metod was used method, which is based on fluorescence. The instrument is called MicroTime 200. It´s very accurate method and results of this are considered like relevant. It was proved that fluorescein as a negatively charged molecule is released less than acridine orange.
|
|
|
Characterization of polyelectrolyte complexes using structural and thermal analysis
Řiháčková, Barbora ; Smilek, Jiří (referee) ; Krouská, Jitka (advisor)
This master thesis deals with study of chitosan-lignohumate, chitosan-polystyrenesulfonate, chitosan-alginate and chitosan-carrageenan polyelectrolyte complexes. The work was motivated by research of finding suitable alternative substance for lignohumate. The molecular weights of substances were characterized using SEC-MALLS. A degree and a character of the interactions between polyelectrolyte were studied by isothermal titration calorimetry and dynamic light scattering method. The calorimetric experiments proved that decreasing concentration of samples causes decreasing of heat flow. The best calorimetric measurements were provided by adding chitosan into polymer solution. The interactions between chitosan and polyanions and influence of mixing order were proved also by measuring intensity of zeta potential, Z-average of particle size and turbidity. New chitosan-based materials have a big potential in agriculture and medicine.
|
|
|
The interactions of hyaluronan and DNA
Sklenářová, Renáta ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
This diploma thesis deals with the study of possible interactions between hyaluronan (HA) and plasmid DNA (pDNA). Plasmid DNA was isolated from E. coli JM109 (pUC19) and resuspended in TE buffer as well as high molecular weight hyaluronan. Individual samples of pDNA, HA and pDNA-HA were characterized by gel electrophoresis, CD spectroscopy and high resolution ultrasonic spectroscopy. Agarose gel electrophoresis examined the effect of the addition of hyaluronan to plasmid DNA on the migration of samples to the positive electrode. Structural changes in pDNA-HA samples were examined using CD spectroscopy. Individual CD spectra describes the dependence of the difference in absorption coefficients for left-hand and right-handed elliptic polarized light at wavelength. High resolution ultrasonic spectroscopy has been used to study interactions. It is an analytical method based on ultrasonic velocity and attenuation. We classify this technique as a non-destructive method because the passing waves do not affect the structure of the analyzed sample.
|
|
|
Veterinary tissue engineering materials
Lavrinčíková, Veronika ; Krouská, Jitka (referee) ; Venerová, Tereza (advisor)
This bachelor thesis focuses on materials that could be used in veterinary tissue engineering, including hydroxyapatite, which is one of the main components of PerOssal® (51,5 % hydroxyapatite, 48,5 % calcium sulphate), which was used in the experimental part of this thesis. The behavior of the PerOssal® pellet in an aqueous environment was observed, which resulted in disintegration into particles. These particles were subsequently analyzed using DLS and SEM methods and ranged in sizes from micrometers for calcium sulfate to nanometers for hydroxyapatite. The main purpose of this thesis was to observe the diffusion characteristics of hydroxyapatite using Rhodamine 6G and PerOssal®. It was found that over 18 days, the pellet gradually released fluctuating concentrations of the fluorescent dye without spontaneously disintegrating, with the most intense release occurring during the first two days of the experiment. PerOssal® has potential use in veterinary medicine, not only as a bone tissue substitute, but also due to its ability to act as a carrier. The pellet can absorb an aqueous drug solution into its volume and subsequently releasing it in small doses over an extended time.
|
|
|
Interactions of pharmaceuticals with humic substances in model hydrogels
Fleischhackerová, Claudia ; Krouská, Jitka (referee) ; Klučáková, Martina (advisor)
This bachelor's thesis is focused on the study of drug diffusion in humic acid hydrogels. The instantaneous surface source diffusion method was used for this study. This method was based on the observation of emerging diffusion profiles of drugs which diffused in the humic gel at certain time intervals. Then, this method was used to determine the diffusion coefficients of the drugs used in the gels. The main aim of the experimental part was to study the influence of the interaction of drugs with humic acids that diffused through the humic gel. Two drugs were used as a diffusing medium, i.e. ibuprofen and tetracycline. They are pharmaceuticals, the consumption has been increasing in humans and animals in recent years, that's why they are often detected in the environment. The concentration profile of these drugs in humic acid hydrogels was determined by UV–VIS spectrometry.
|
|
|
Heat effects of microbial life in soil
Drápalová, Karolína ; Kalina, Michal (referee) ; Krouská, Jitka (advisor)
This research is intended to be an application of calorimetry to the study of thermal manifestations of microbial life in soil. Although this research has slowly but steadily expanded over the past half century, many unanswered questions still remain. Calorimetry is a suitable tool for determining several parameters of soil quality. Therefore, it is a very important indicator for agriculture. Very well-known indicators used in soil research can be measured by various calorimetric methods such as differential compensation calorimetry (DSC) and thermogravimetry (TG), which are temperature scanning methods used to estimate certain properties of soil material. Calorimetry can be used to determine the activity of microbial life in the soil, which is an essential parameter for the proper functioning of the soil, i.e. for its health. Microorganisms will release a certain amount of heat, based on their metabolism, which can be boosted by adding certain nutrients. We can therefore say that the presence of microorganisms in the soil can be detected thanks to calorimetry.
|
|
|
Analysis and optimization of the dyeing process of surgical instruments
Roušarová, Kateřina ; Jugl, Adam (referee) ; Krouská, Jitka (advisor)
This bachelor thesis deals with the issue of staining of disposable surgical instruments in the corporate facility of the industrial partner with whom the cooperation took place. Within the framework of this bachelor thesis an analysis of the input organic raw materials, which are an essential part of the manufactured dye for instrument staining, was carried out. The basic characterization of the raw materials was carried out by available methods at the Faculty of Chemistry, such as density measurement with a hydrometer, viscosity measurement with an automatic viscometer and viscosity versus shear rate with a rheometer. Subsequently, a visual assessment of the behaviour of the individual liquid feedstocks in water was performed. The tabulated values of the raw materials from the safety data sheets were verified by these methods. It was found that the starting ingredients are insoluble in water, in which they precipitate and thus significantly affect the viscosity of the resulting suspension. The actual laboratory preparation of the paint samples was carried out, where 7 samples were mixed, varying in the volumes of the input liquid organic components. These samples were subjected to rheological measurements, which resulted in the dependence of viscosity on shear rate. A range of 0,4–0,8 Pas at a shear rate of 10 s-1 was specified by the industrial partner for the resulting viscosity of the mixed suspension, within which 4 samples fell. The result of the spout test performed using a Ford spout cup determined the time of suspension discharge from the cup, which can be used to verify the quality and correct consistency of the paint mixed in company operation. All samples were stained with surgical instruments and the quality of staining was evaluated after firing. Based on the requirements of the industrial partner, 4 samples were designed falling within the required viscosity range and suitable for staining surgical instruments. The results have been passed on to the industrial partner, who has the discretion to implement new dye preparation procedures in their operation.
|
guest ::
