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An investigation of lubrication of knee joint replacement
Sýkora, Tomáš ; Horák, Zdeněk (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of knee joint replacement lubrication. The experiments were realized at a knee joint simulator which can apply conditions according to certain standard and survey the phenomena by using fluorescence microscopy. The aim of thesis is to clarify the influence of particular components of synovial fluid on the lubrication process. The intensity of fluorescence expresses dimensionless parameter of a lubrication film thickness. There was a fundamental study with mineral oils before the experiments with the synovial fluid. The study allows to have a look at contact transformation during walk. Results are shown in graphs as dependency of intensity on time, including pictures showing phenomena in the contact zone. Experiment results show that protein -globulin creates a layer on the surface. There is albumin on the layer and it makes the lubricating film thicker. The protein interaction is supported by hyaluronic acid and fosfolipids which stabilizes the created structure. According to lubrication is behaviour of film related to a complex structure of synovial fluid. Thesis gives more information about behaviour of synovial fluid and can be used for future development of knee replacements.
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SEC-MALLS study on hyaluronan-albumin interactions
Sereda, Alena ; Kalina, Michal (referee) ; Chytil, Martin (advisor)
This work is focused on interactions of hyaluronan (HA) and bovine serum albumin (BSA). These interactions were studied by SEC-MALLS method, where molar mass, root mean square (rms) radii, hydronamic radius and intrinsic viscosity of particles of the system were defined. Additionally, interactions were examined by measurement of DLS and zeta potential, where hydrodynamic radius and a value of the zeta potential were defined. The interactions were confirmed at any of the used media, but with different efficiency. Furthermore it was found out, that the high ionic strength minimizes the range of the interactions, magnifies the radii of the complexes, their intrinsic viscosity and zeta potential. It was proved that complexes become smaller in their radii and viscosity with growing BSA concentraton.
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Polysaccharide-protein gels
Hájovská, Pavla ; Smilek, Jiří (referee) ; Chytil, Martin (advisor)
This bachelor thesis deals with gelation of albumin solutions and mixed solutions of albumin and the high molecular weight hyaluronic acid due to heating. Study was carried out by measuring rheological properties of the solutions, formed gels and gelation process. For the protein samples in water, the effect of concentration, ionic strength and pH were tested. For mixed solutions, the effect of concentration and a composition of the polymeric component were tested. With increasing concentration of the polymeric component, the gel point is shifted towards lower temperature values, with the concentration difference of 2 % (w/v) up to 5°C. The resulting gels exhibit higher values of loss and storage moduli. Similar behavior was observed also in the samples influenced by the ionic strength as, a result of alternation of the electrostatic interactions between the charged groups of the polymer chains and as a result of change of this charge due to the pH reduced below the pI value of the protein.
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Optimization of methods for protein analysis released from thermosensitive hydrogel
Lysáková, Klára ; Brtníková, Jana (referee) ; Vojtová, Lucy (advisor)
Předložená diplomová práce je zaměřena na metody hodnocení modelových proteinů (albuminu a lysozymu) a tkáňového léčivého proteinu (stabilního fibroblastového růstového faktoru 2; FGF2-stab) z „inteligentního“ hydrogelového nosiče na bázi biologicky odbouratelného termosenzitivního PLGA-PEG-PLGA triblokového kopolymeru. V teoretické části je zpracován stručný přehled termocitlivých polymerů, jejich vlastnosti, struktura a využití výše uvedených proteinů. Dále jsou zmíněny typy interakcí, které mohou nastat mezi proteiny a polymerními nosiči. V experimentální části byla struktura blokového PLGA-PEG-PLGA kopolymeru charakterizována gelovou permeační chromatografií a 1H NMR, zatímco jeho viskoelastické vlastnosti včetně sol-gel přechodu byly hodnoceny reologickou analýzou. Hlavním cílem práce bylo lepší pochopení uvolňování nově patentovaného FGF2-stab proteinu z injektovatelného PLGA-PEG-PLGA hydrogelu tvořícího při gel při fyziologické teplotě. Množství uvolněného FGF2-stab bylo měřeno UV-VIS spektrofotometrem v přítomnosti Bradfordova činidla, které se váže na proteiny, což vede k posunu jejich absorpčních maxim z 280 nm na 595nm. Pro srovnání byla použita SDS-page elektroforéza, dělící protein podle molekulové hmotnosti. Bylo zjištěno, že modelové proteiny, které byly různé velikosti, ale převážně nepolární povahy, vykazovaly dvoustupňové uvolňování, zatímco FGF2-stab (25 kg.mol-1) vykazoval z PLGA-PEG-PLGA hydrogelu řízené jednostupňové uvolňování, které probíhalo pouhou difúzí, jelikož se jedná převážně o polární molekulu, která se nachází pravděpodobně na povrchu micel, a ne v jejich jádru. Tyto výsledky jsou velmi důležité pro vyladění uvolňování proteinů z hydrogelových nosičů tak, aby vyhovovaly určité aplikaci, v tomto případě řízené regeneraci tkání.
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Investigation of Polyelectrolytes Interactions with Cationic Aminogroups-containing Amphiphiles
Zeman, Jan ; Běťák, Jiří (referee) ; Chytil, Martin (advisor)
The study deals with interactions of polyelectrolytes polystyrene sulfonate and hyaluronic acid with nitrogenic amphiphilic substances, represented by lysine and albumine. To study the interactions pH-metry, conductance, viscositic and turbidity measurement, DLS and reometry were used. All mixtures of different concentrations were measured and the data were compered with data obtained from measurement of samples with amphiphilic sumstances without polyelectrolytes. Observed interactions occured in the aminoacid concentrations between 0 to 20 mmoldm-3, then the PSS interaction groups were fully bonded by lysine and no more interactions were recognized. The same behaviour were observed in albumine solutions with concentration under 2 gdm-3.
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Experimental analysis of lubricant film formation in hip joint replacements
Švachová, Michaela ; Dzimko, Marián (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of lubricant film formation in hip joint replacements. The main objective is to clarify the effect of mean speed, slide-to-roll ratio, and material of femoral head on the development of film thickness, focusing on the role of particular constituents contained in model synovial fluid, such as albumin and -globulin. For this purpose, a model ball-on-disc configuration was applied, while the development of lubricant film was evaluated using the combination of fluorescent microscopy and optical interferometry. To better understand the process, coefficient of friction between implant surfaces was later investigated as well. The effect of material, slide-to-roll ratio, mean speed and model fluid composition was analysed. Results indicate that the main parameter, influencing the character of film formation, is slide-to-roll ratio. Under most conditions, the dominant constituent responsible for the film thickness development was albumin. Coefficient of friction is affected mainly by the material of implant. The thesis contains original scientific results extending the knowledge in the area of hip joint biotribology.
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Influence of surface microstructure on implant lubrication processes in contact
Matovič, Martin ; Odehnal, Lukáš (referee) ; Ranuša, Matúš (advisor)
This bachelor thesis deals with the lubrication of microstructured prostheses of the first metatarsophalangeal joint. The aim of the research is the service life of joint replacements by creating a microstructure on the surface of the material. The work focuses on the influence of microstructures on lubrication processes in contact and coefficient of friction. Fluorescence microscopy in combination with a reciprocating tribometer with the possibility of recording frictional and loaded forces was used to observe the contact area. The number and average particle size of albumin, which plays an important role in contact lubrication, were then examined to record the camera. The testing was performed on two material combinations, namely CoCrMo - Glass B270 (hard pair) and CoCrMo - PMMA (soft pair), which were only four different microstructures. Elsewhere, the influence of microstructures on lubrication processes in contact for hard and soft pairs is indicated, which can be used to design further measurements.
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The Effect of Synovial Fluid Constituents on Lubrication of Hip Joint Replacements
Nečas, David ; Daniel,, Matej (referee) ; Sawae, Yoshinori (referee) ; Hartl, Martin (advisor)
Dizertační práce se zabývá mechanismy mazání v náhradách kyčelního kloubu. Byla provedena systematická studie formování proteinového filmu při zahrnutí různých materiálů a provozních podmínek. Hlavní pozornost je přitom věnována roli jednotlivých proteinů obsažených v synoviální kapalině při současné přítomnosti dalších proteinů. Jelikož metody aplikované v předchozích studiích neumožňovaly separovat jednotlivé složky maziva, byla vyvinuta optická měřící metoda na principu fluorescenční mikroskopie. Z důvodu verifikace metody byly provedeny dvě nezávislé studie zaměřené na měření tloušťky mazacího filmu a dělení maziva na výstupu mazaného kontaktu. Z důvodu určitých limitací fluorescenční mikroskopie byla dále využita i metoda optické interferometrie, jejíž využití je ilustrováno ve studii zabývající se formováním mazacího filmu v náhradách kyčelního klubu při uvažování reálné konformity třecích povrchů. Závěrečná část práce představuje nový metodologický přístup založený na in situ pozorování kontaktní oblasti umožňující popsat roli jednotlivých proteinů ve vztahu k vývoji tloušťky mazacího filmu. Práce obsahuje originální výsledky, které přináší nové poznání v oblasti biotribologie náhrad kyčelního kloubu vedoucí k dalšímu vývoji implantátů při snaze zabránit jejich selhání v důsledku omezené životnosti.
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Study of hyaluronan-albumin systems using light scattering methods and calorimetry
Sereda, Alena ; Hermannová, Martina (referee) ; Chytil, Martin (advisor)
This thesis, which is a continuation of the previous Bachelor thesis, is dedicated to the study of polyelectrolyte complexes between hyaluronan (HA) and bovine serum albumin (BSA). Interactions between HA and BSA and a formation of complexes were studied by SEC-MALLS method, where a molar mass, a root mean square (rms) radius, a hydronamic radius and an intrinsic viscosity of particles of the system were defined. Furthermore the interactions were studied by calorimetric measurement ITC, where thermodynamic character of complex formation was determined. Additionally, dynamic and electrophoretic light scattering methods (DLS and ELS) were applied, where hydrodynamic radius and a value of the zeta potential were defined. Also the effect of higher temperature on the character and complex formation was examined by SEC-MALLS and ITC measurements. The interactions were confirmed at any of the used media, but with different efficiency. It was also proved that complexes become smaller in their radii and viscosity with growing BSA concentration. Furthermore it was proved, that the high ionic strength hinders surface charges of HA and BSA molecules and minimizes their mutual interactions. At the higher ionic strength the radii of the complexes, their intrinsic viscosity and zeta potential are increased. The higher temperature has only minimal effect on the formation of the complexes.
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Analysis of THR lubrication with the use of fluorescent microscopy
Tkadlec, Tadeáš ; Daniel, Matej (referee) ; Nečas, David (advisor)
This diploma thesis deals with an experimental analysis of lubrication of total hip joint replacement using fluorescence microscopy, focusing on so-called soft bearing pairs. Experiments were realized using a hip joint simulator, which was modified and refined for fluorescence microscopy. The aim of this diploma thesis was to determine the effect of the individual components of the synovial fluid on the lubrication mechanisms. For this purpose, different model fluids were designed to represent the composition of proteins and other synovial fluid constituents to elucidate the effect of albumin, -globulin and hyaluronic acid on the resulting lubrication performance. The experiments were separate into two categories different in type of load, dynamic (representative walking) and combined (representing standing with short walk). The experimental results were time-dependent fluorescence intensity values, representing dimensionless film thickness parameters. The values were recorded on the graphs and supplemented with fluorescence images taken during the characteristic sections of the measurements. The measured data was subsequently confronted with previously published articles. It was found that the dominant constituent responsible form film thickness is albumin, while -globulin and hyaluronic acid forms thin stable layer enhancing adsorption ability of albumin which contributes to increase of film thickness eventually.
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