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Study of the interaction of lung surfactant with selected polymers
Suchá, Klára ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
This thesis deals with the study of interactions between pulmonary surfactant (Curosurf) and selected polymers (N,N,N-trimethylchitosan, polyvinylpyrrolidone, sodium hyaluronate). This work also focuses on the inactivation of lung surfactant using bovine serum albumin, which causes an increase in the surface tension of the surfactant, whereby the inactivated surfactant is unable to fulfill its function in the lungs. The addition of polymers to this mixture has been shown to be an effective means of restoring the surface tension of the surfactant. First of all, this work focuses on finding the optimal concentration ratios of polymer and Curosurf, at which their mutual interaction occurs. The method of dynamic light scattering was used to obtain optimal ratios. In the second part, the work is devoted to the determination of surface tension using a du Noüy ring tensiometer. It was found that the addition of all selected polymers led to a reduction of the surface tension of the inactivated surfactant to values close to native Curosurf. This work provided useful information to understand the mechanism of lung surfactant surface tension recovery.
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The effect of bio-pigments on the properties of PLA materials for 3D printing
Vacula, Jan ; Figalla, Silvestr (referee) ; Menčík, Přemysl (advisor)
This thesis deals with the influence of naturally derived dyes on the properties of polylactic acid (PLA) for 3D printing using the FDM method. In the production of 3D printing filaments, it was crucial to understand the behavior of bio-dyes within the material. Thermogravimetric analysis (TGA) was performed to determine the thermal stability of the bio-dyes. Based on the resulting thermal stabilities, seven bio-dyes were selected from which concentration series were prepared in the form of 3D printing filaments. The influence of adding bio-dyes to the PLA polymer matrix was defined using gel permeation chromatography (GPC). To assess the impact of bio-dyes on the mechanical properties of the materials, tensile testing and three-point bending tests were chosen. It was found that adding bio-dyes does not significantly reduce mechanical properties. Furthermore, UV stability was investigated through accelerated exposure in a chamber with a xenon lamp. The influence of UV radiation on individual bio-dyes was defined through colorimetric evaluation. The results were key for further development and optimization of the use of natural dyes in the manufacturing process of 3D printing filaments.
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Alternative crosslinking methods for sodium alginate resulting in hydrogels with suitable application properties
Kouřilová, Ludmila ; Kráčalík, Milan (referee) ; Smilek, Jiří (advisor)
This diploma thesis is focused on the preparation of alginate gels with the potential to influence their final application properties (transparency, syneresis, viscoelastic properties, etc.). Based on literature review, a total of three gelation strategies leading to the gelation of sodium alginate were selected, namely ionotropic gelation by external gelation method, ionotropic gelation by internal gelation method, and alginate crosslinking with phytic acid, which is capable of forming both ionic bonds and intramolecular hydrogen bonds. Subsequently, the preparation of alginate gels was optimized, their mechanical properties were characterized, and finally, the influence of several factors (polymer concentration, amount of crosslinking agent, gelation time, addition of sucrose, etc.) on the resulting properties of the prepared gels was monitored. Within the scope of the thesis, it was demonstrated that the resulting properties of sodium alginate-based gels are influenced not only by the polymer concentration, the amount of crosslinking agent used, gelation rate, or syneresis, but in the case of ionotropic gelation by external gelation, for example, also by the type of anion used. An interesting part of the thesis is also the optimization of determining the mechanical properties of alginate gels through compression tests. During these tests, the sample is compressed between two rheometer sensors, and the mechanical response of sample to the applied force is measured. It is one of the most easily conceivable rheometric tests.
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Computer modeling of interactions between hyaluronan and polylysine
Zlochová, Barbora ; Řeha,, David (referee) ; Minofar, Babak (advisor)
Hyaluronic acid is a biosaccharide naturally occurring in human tissues. As a biomaterial with a number of interesting properties, it is the subject of interest in many industrial areas such as cosmetics and medicine. It is generally known that hyaluronic acid polymers interact with peptide polymers to form complexes with various physical properties, with great potential in the field of material science. In this work, the aim was to characterize the formation of just such complexes on the case of one polymer fiber of hyaluronic acid with polylysine fibers with different numbers of lysine subunits. In the theoretical part of the work hyaluronic acid and polylysine are described in terms of their general structural properties, uses and interactions, general computational chemistry is explained, principles and parameters of molecular dynamics MD are defined, and finally the MD simulation scheme according to which the simulations in this work were built is described. In the experimental part of the work, the upcoming simulation systems PLL8, PLL10, 1HA25-8PLL10, 1HA25-10PLL10, 1HA25-12PLL10 together with the parameters and tools that were used for their construction, the work in the GROMACS environment, in which the entire construction of the simulation systems took place, was described, the preparation of the MD simulation systems itself, the start of their computational solution and analysis in the MetaCentrum was also described. In the simulated systems, the number of hydrogen bonds between the HA polymer fiber and PLL peptides of different concentrations and their interactions with the surrounding solvent were analyzed. The radius of gyration of the HA polymer fiber in the presence of PLL peptides at different concentrations was studied. The radial distribution function of the terminal residues on the PLL fibers in the vicinity of the terminal residues on the HA surface at different PLL concentrations was determined. By analyzing the data, we managed to define and determine how the interaction between HA and PLL complexes changes.
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Polymeric blends of thermoplastic starch with other biodegradable polymers
Nováková, Pavlína ; Petruš, Josef (referee) ; Kučera, František (advisor)
The master's thesis deals with the preparation and properties of biodegradable polymer blends of thermoplastic starch (TPS) with polyhydroxybutyrate (PHB) with emphasis on the compatibilization of the immiscible polymer blend. The theoretical part focuses on the characterization of thermoplastic starch, thermodynamics of polymer blends, possible ways of compatibilization of polymer blends and a summary of the current knowledge on polymer blends of thermoplastic starch with biodegradable polymers. The experimental part deals with the modification of starch and PHB with maleic anhydride in order to compatibilize the polymer blend. The binding of the monomer to the polymers was confirmed by infrared spectroscopy and acid-base titration. Subsequently, using the prepared modified polymers, TPS/PHB blends were prepared and the effect of compatibilization and blend composition on the properties was evaluated. Differential scanning calorimetry (DSC) was used to observe the melting and crystallization process, the changes in molecular weight of the polymers were assessed by determining the melt flow index. Tensile strength, elongation at break and the effect of ageing on the mentioned mechanical properties were determined by tensile testing, morphology was observed by electron microscopy (SEM).
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Fabrication and characterization of advanced microfluidic chips
Vejrosta, Jakub ; Novotný,, Jakub (referee) ; Plichta, Tomáš (advisor)
This diploma thesis deals with the design, fabrication and verification of microfluidic chips that can be used to sort particles using surface acoustic and standing surface acoustic waves. The sorting function of this chip is based on the piezoelectric properties of the substrate. For this reason, lithium niobate was selected as the substrate. The acoustic waves are generated by interdigital transducers placed directly on the surface of the substrate, which were fabricated by metal layer evaporation, optical lithography and reactive ion beam etching techniques. The microfluidic channels were made from a biocompatible polymer, polydimethylsiloxane, and subsequently bonded to the substrate with the interdigital transducers already prepared. The correctness of fabrication and assembly of the optimized microfluidic chips was subsequently verified experimentally by sorting polystyrene particles of different diameters. Another application of these chips was the preparation of oriented structures of the bacterium Cupriavidus necator H16 using surface acoustic waves.
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Transport and mechanical properties of hybrid hydrogel networks based on gellan
Sokolínský, Jan ; Pekař, Miloslav (referee) ; Kalina, Michal (advisor)
This diploma thesis deals with the characterization of the mechanical and transport properties of gellan based hybrid hydrogels. As part of this work, the process of optimizing the preparation of gellan-poly(vinylalcohol) IPN hydrogel was first studied with an emphasis on the repeatability of the preparation due to the preservation of mechanical properties of the hydrogel. Then, both on the gellan hydrogels themselves and on selected IPN compositions, the effect of various additives was studied (specifically, the effect of the addition of a plasticizer and the effect of cross-linking by polyvalent ions). Based on these tests, a set of samples was selected, on which dynamic mechanical analysis, swelling and drying experiments were additionally measured. At the end of this diploma thesis, the transport properties of selected hydrogel compositions were also studied. The tests conducted in this thesis revealed that both the formation of a dual network and the addition of the mentioned additives allow us to influence the studied properties.
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Controlled modification of tips usable for selected measurement modes of atomic force microscopy
Lišková, Kateřina ; Szabová, Jana (referee) ; Smilek, Jiří (advisor)
This master's thesis deals with the modification of tips commonly used in atomic force microscopy and their following utilization for determining the mechanical properties of selected hydrogel systems at the local level. For targeted modification, a method of micro-particle fixation on a cantilever was chosen, which was successfully modified using melamine resin particles. Initially, the mechanical properties of a selected representative of physically cross-linked hydrogels (agarose polysaccharide) were measured, which were evaluated based on the Young's modulus of elasticity, adhesive force, and work. The obtained results were compared with values measured using two commercially available cantilevers differing in both shape and basic parameters such as spring constant and resonance frequency. Subsequently, the influence of the setpoint force applied to the sample by the cantilever was verified. The usability of modified cantilevers was also tested on a selected representative of ionically cross-linked hydrogels (sodium alginate cross-linked with multivalent ions). Within the experimental part of the master's thesis, it was verified that the use of cantilevers with a higher contact area leads to more reliable results in terms of reliability and reproducibility, considering that the final value of the Young's modulus includes not only the contribution of the polymer chain but also the pores. When determining mechanical values, it is important to specify not only the cantilever used and its properties but also all other experimental parameters, the change of which may affect the final values of the Young's modulus determined at the micro level by atomic force microscopy.
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Magnetic nanoparticles with antibacterial properties: Synthesis, characterization and biological applications
Shatan, Anastasiia-Bohdana ; Horák, Daniel (advisor) ; Kaman, Ondřej (referee) ; Matějíček, Pavel (referee)
In response to the escalating global threat of antibiotic resistance, innovative strategies are imperative. This thesis focuses on surface-engineered magnetic nanoparticles (MNPs) with potent antibacterial properties, aiming to combat antibiotic resistance effectively. Specifically, uniform 16-nm Fe3O4 nanoparticles were synthesized via oleic acid-stabilized thermal decomposition of Fe(III) oleate in a high-boiling organic solvent. Optionally, 8-nm γ-Fe2O3 particles were obtained by coprecipitation of Fe2+ and Fe3+ salts in a basic medium. For the application of antibacterial MNPs in biological media, water-dispersible nanoparticles were required. Hence, original magnetic particles containing hydrophobic oleic acid (OA) coating were modified with silica using a water-in-oil reverse microemulsion. Subsequent modification with (3-mercaptopropyl)trimethoxysilane and decoration with silver nanoclusters yielded Fe3O4@SiO2-Ag nanoparticles. Additionally, neat Fe3O4 particles were coated with Sipomer PAM-200 containing both phosphate and methacrylic groups, facilitating attachment to the iron oxide and enabling (co)polymerization with 2-(dimethylamino)ethyl methacrylate and/or 2- tert-butylaminoethyl methacrylate. Furthermore, γ-Fe2O3 nanoparticles were rendered antimicrobial through modification with...
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Macromolecular avenues for the creation of bio-inspired hierarchically structured surfaces
Wang, Yu-Min ; Pop-Georgievski, Ognen (advisor) ; Kostka, Libor (referee) ; Sedláček, Ondřej (referee)
Biomedical applications often rely on surface adherent architectures such as polymer brushes to prevent adverse nonspecific interactions between materials used in biomedicine and contacting biological fluids. Commonly, "grafting-to" (GT) and "grafting-from" (GF) methods are used to attain the polymer brush architecture on various surfaces. This study investigates the grafting density and antifouling effectiveness of poly[N-(2-hydroxypropyl) methacrylamide] (poly(HPMA)) brushes synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization, employing both GT and GF techniques. To determine the molar masses of solution-born and GF poly(HPMA), size exclusion chromatography (SEC) equipped with multiple angle laser light scattering (MALS) and atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) were combined and thoroughly used. Furthermore, the impact of solvent effects on polymer brush propagation kinetics during the concomitant surface-initiated- (SI-) RAFT process between surface and solution was investigated. Experimental findings revealed discrepancies between GF and solution-born poly(HPMA) chains. Notably, solvent composition influenced both the propagation rate and the inferred grafting density of surface-grafted poly(HPMA) due to variations in...
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