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Biosensors based on modified carbon nanotubes
Ferdusová, Helena ; Majzlík, Petr (referee) ; Hubálek, Jaromír (advisor)
The aim of this work is to describe biosensors for detection of substances in liquids using modified carbon nanotubes. This work reports on knowledge about nanotubes and electrochemical analysis methods which were used. The matter of direct electrochemical detection of insulin using CNTs modified thick layer planar carbon nanotubes is discussed. The elementary working electrodes were created by using of commercial carbon paste and were modified by thin film CNTs, CNTs/ruthenium oxide and CNTs/chitosan then. The best results of the insulin detection were achieved with the working electrodes modified by low concentration non-purified CNTs which had low elementary response in electrolyte and good response to increasing concentration of insulin in the concentration range from 0, 25 to 10 mol/L. The other modifications caused increasing of the electrode elementary response, but they did not significantly affect the detection.
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3D tisknuté sensory pro detekci cukru v nápojích
Zichová, Anežka
Sugars are one of the most common ingredients in food industry, due to their diverse usage as technological component as well as sweetening element. The issue of sugar utilization is not only topic of food industry but plays a key role in human nutrition at the same time. The intake of simple sugars from food, particularly from sweetened beverages, is a major concern from a nutritional standpoint. Carbohydrates can be detected in variety of ways. A literature review was conducted on the methods used in food science, which is based on the previous characterization of the most frequently used sugars in food industry like sucrose, maltose, glucose, fructose, inverted sugar, and glucose-fructose syrup. The chemical, technological and nutritional properties of carbohydrates were described. Considering this examination, 3D printed electrodes were designed for detection of sugar, namely glucose, in beverages. In consideration of the available literature, electrochemical enzymatic biosensors were designed, using glucose oxidase as the sensing element to detect glucose in beverages. The electrodes, carrying the enzyme, were printed from PLA and graphene based conductive filaments. The electrodes were activated in chemical and electrochemical way. To bind the enzyme, a technique based on cross-linking and immobilization was used. Chronoamperometry and cyclic voltammetry were used to test the biosensor. Afterwards the real sample of a fruit juice-based non-alcoholic beverage was examined. The results were interpreted in the context of the applicable legislation of the European Union and, likewise, the legislation of the Czech Republic, in regard to the required data on food labels.
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Graphene dopamine biosensor and gate effect
Krajíčková, Kateřina ; Šimšíková, Michaela (referee) ; Bartošík, Miroslav (advisor)
This bachelor’s thesis focuses on investigating the interaction between biochemical substances (dopamine solutions) and graphene, using field effect transistor (FET) based sensors. Graphene possesses unique properties, including biocompatibility, high charge carrier mobility, and surface sensitivity, making it an ideal material for biosensing devices. In these sensors, graphene is employed as the conductive sensing channel within fieldeffect transistors. By utilizing sensors with an FET arrangement, the doping of graphene induced by adsorbed atoms or molecules can be experimentally determined through the observation of the shift in the position of the Dirac point. The measurements can be performed using either the bottom-gated or electrolytic top-gated configuration of the FET sensor, and the thesis explores the differences between the two setups. Furthermore, it investigates the impact of the distance between the graphene and top-gate electrode on the sensor’s response. The results of these measurements are represented by transfer curves, which exhibit characteristic peaks indicating the charge neutrality point, known as the Dirac point, of graphene.
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Detection of DNA/RNA fragments using graphene sensor and influence of upper electrolytic gate
Herzánová, Kristína ; Konečný, Martin (referee) ; Bartošík, Miroslav (advisor)
Jedinečné vlastnosti grafenu, jako je biokompatibilita, vysoká mobilita nosičů náboje a povrchová citlivost, z něj činí vhodný materiál pro biosenzory. Cílem této práce je popsat a představit takové senzory a měření provedená za účelem detekce fragmentů DNA, konkrétně látek na bázi cytosinu. Grafen je v polem řízených tranzistorech zapojen jako vodivý snímající kanál. Dopování grafenu vyvolané adsorpcí molekul na vodivém kanálu způsobuje změny transportních vlastností grafenu. Tyto změny se odrážejí v měření elektronických odezev: měření odporu grafenové vrstvy reagujícího v reálném čase na přidávání různých roztoků a závislost odporu na průběžné změně hradlového napětí. Druhou metodu měření lze provádět FET senzorem zapojeným v konfiguraci se spodním nebo elektrolytickým horním hradlem. Je sledován rozdíl mezi oběma konfiguracemi a také vliv vzdálenosti mezi grafenem a horní hradlovou elektrodou na odezvu senzoru. Výsledkem těchto měření jsou transferové křivky vykazující typické píky označující bod neutrality (Diracův bod) grafenu. Různé koncentrace roztoku analytu vedou k různým hodnotám napětí Diracova bodu, což slouží ke kvantifikaci úrovně dopování grafenu.
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Study of Biomolecular Interactions with Surface Plasmon Resonance Biosensors
Šípová, Hana ; Homola, Jiří (advisor) ; Houska, Milan (referee) ; Skládal, Petr (referee)
Surface plasmon resonance (SPR) biosensors represent one of the most advanced sensing technologies for real-time studies of biomolecular interactions. In this thesis, methods for functionalization of SPR substrates were optimized and studied via spectroscopic methods. Effects related to the SPR sensor microfluidic interface on the measured biomolecular interactions were analyzed, and furthermore, means to decrease mass-transport limitations were proposed. Several SPR-based assays regarding the detection of nucleic acids were developed, which allow for the detection of physiologically relevant concentrations of nucleic acids as well as point mutations in a nucleic acid sequence. Assays for the determination of the enzymatic activity of HIV integrase and ribonuclease H were developed. These assays can be employed for the design and synthesis of molecules that function either as antiviral drugs or as gene-regulating agents.
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Analysis of Src dynamics in cellular structures
Pelantová, Markéta ; Rösel, Daniel (advisor) ; Rozbeský, Daniel (referee)
Src kinase is a key element in many signaling pathways affecting cellular processes such as differentiation, proliferation, motility, or migration. Deregulation of its activity is associated with the promotion of cancer. Therefore, understanding its cellular function is vital. Src activity directly correlates with its structure; when Src is active, it adopts opened conformation, when inactive, it is in closed conformation stabilized by intramolecular interactions. Detection of the conformation can be used to analyze Src activity. In this thesis, conformation-sensitive FRET-based Src biosensor was improved using mNeonGreen as a new acceptor fluorophore in the existing design and the properties of the new biosensor were compared with the original Src biosensor. The new biosensor is able to detect changes in Src conformation and can be stably expressed in cells. Src activity in focal adhesion was analyzed and higher Src activity in these structures was confirmed. Although the new biosensor did not exhibit significantly better sensitivity to Src conformational changes, it still proved to be a useful tool to study Src activity, and mNeonGreens higher brightness makes it more suitable for microscopic experiments. Key words: Src, FRET, biosensor, live-cell imaging, mNeonGreen
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Biosensors based on functionalized graphene
Pavlásková, Lucie ; Skládal, Petr (referee) ; Bartošík, Miroslav (advisor)
V této práci byl demonstrován grafenový polem řízený transistor (GFET) jako platforma pro detekci glukózy. Sukcinimidyl ester pyrenbutanové kyseliny (PSE) sloužící jako nosič a enzym glukóza oxidáza (GOx) byly úspěšně použity k funkcionalizaci grafenového kanálu ve FE transistoru. Enzym GOx byl imobilizován na kanálu pro glukózovou detekci, jelikož indukuje selektivní katalytickou reakci glukózy. Proces funkcionalizace byl charakterizován pomocí Ramanovy spektroskopie a Atomární silové mikroskopie (AFM). Vyrobený biosenzor na bázi grafenu umožnil elektrickou detekci glukózy ve dvou různých uspořádáních. V uspořádní FET prostřednictvím posunu Diracova bodu ve voltampérové charakteristice, jakož i v nastavení pro kotinuální monitorování v reálném čase prostřednictvím změny odporu grafenového kanálu. Tato studie naznačuje, že grafen je slibným materiálem pro vývoj nanoelektronických biosenzorů včetně aplikací pro monitorování hladiny glukózy.
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DESIGN OF FIBER-OPTIC BIOSENSOR WITH NEAR-INFRARED SPECTRAL ANALYSIS
Křepelka, Pavel ; Jakubec,, Martin (referee) ; Skládal, Petr (referee) ; Mikulka, Jan (advisor)
This thesis deals with a measurement and interpretation of NIR spectra of bacterial cells and design of biosensor using this analytical technique. In the first chapter, there is introduction of current state of knowledge in the field of NIR spectroscopy in microbiology and technology of fiber optic biosensors. The summary of this chapter shows that NIR is a suitable technique for direct molecular analysis of bacteria, but it suffers from low sensitivity and insufficient interpretation of bacterial spectra. In the next part of the thesis, there is a theoretical background of spectral analysis techniques and technology of fiber optic sensors. In the practical part of this work, there is suggested the elimination of disadvantages of NIR spectroscopy in microbiology by a series of experiments used for interpretation of NIR spectra of bacteria and design of fiber optic sensor to increase sensitivity of this technique. In this work, spectral regions important for the identification of bacterial strains were determined and partially interpreted and the sensor for bacterial analysis capable of classifying strains based on 105 captured cells was designed. Therefore, the objectives of this work were fulfilled.
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Printed Biosensor Based on Organic Electrochemical Transistor
Omasta, Lukáš ; Mikula, Milan (referee) ; Boušek, Jaroslav (referee) ; Salyk, Ota (advisor)
Organické elektronické zariadenia sú vyvíjané ako vhodné riešenia senzorov pre bioelektroniku, a to najmä kvôli dobrej biokompatibilite organických polovodičov v nich použitých. Takzvané biosenzory dokážu premeniť elektrochemické procesy na elektronický signál. Matrica takýchto biosenzorov môže simultánne skenovať množstvo biologických vzoriek, alebo rôznych tkanív v živých systémoch. Aktívnou súčasťou zariadenia je organický elektrochemický tranzistor (OECT). V tejto práci je diskutovaný teoretický rámec fungovania takéhoto zariadenia, jeho elektrická charakterizácia, aplikácia v biosenzoroch na báze buniek, spôsoby výroby a aktuálnym stavom techniky v oblasti organickej elektroniky. Experimentálna časť obsahuje konkrétne výrobné postupy vývoja OECT zariadení, ktoré boli použité v našom laboratóriu. Hlavný dôraz sa kladie na schopnosť vyrobených zariadení detekovať reakciu a monitorovať stimuláciu elektrogenných buniek. Za týmto účelom boli vyvinuté matice mikroelektródových OECT zariadení založených na polovodivom polyméri PEDOT:PSS. Tieto boli vyrobené s využitím bežnými tlačiarenských techník (atramentová tlač a sieťotlač) spolu so štandardnými litografickými postupmi. Najnovšie nami vyvinuté zariadenia dosahujú najväčšieho zosílením signálu, g = 2,5 mS a časovú konštantu t = 0,15 s. Tieto zariadenia sú porovnateľné, často dokonca lepšie ako niektoré iné najmodernejšie a plne litograficky pripravené senzory.
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Microelectrode arrays for mioelectronic
Bráblíková, Aneta ; Vala, Martin (referee) ; Salyk, Ota (advisor)
Organic electronic biosensors are developed as suitable devices that can transform electrochemical processes within the cell membrane into an electronic signal and enable to measure electrical activity of excitable cells and tissues both in vitro and in vivo and thus represent valuable alternative to current cell monitoring methods. In this work we focus on the fabrication of electrophysiological sensors based on organic semiconductors printed by the material printing method. Microelectrode arrays (MEAs) are active components of the device, which can monitore cellular activity and above that stimulating cells with electrical pulses. The proposed platform should be used for cytotoxicity of potential drugs especially on cardiac cells (cardiomyocytes). The experimental part focus on specific production processes of platforms, which were prepared in the laboraty with emphasis on biocompatibility and conductivity of device.
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