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Development and utilization of electrochemical flow-through detectors
Baroch, Martin ; Dejmková, Hana (advisor) ; Vyskočil, Vlastimil (referee) ; Trnková, Libuše (referee)
The proposed dissertation thesis deals with the development and investigation of electrochemical flow systems using both conventional and unconventional electrode materials. In the first part of this thesis, the problem of porous flow-through large area electrodes is addressed. As a working electrode material, a free-standing porous boron-doped diamond (fs-pBDD) was used. This was used for the first time in the construction of an electrochemical cell designed for amperometric detection in flow methods. Testing of this electrode was performed using amperometric detection combined with flow injection analysis of a ruthenium complex solution. The detection limits achieved on this material were in the submicromolar range and the linear dynamic range of the concentration dependence spanned over three orders of magnitude. In addition to amperometry, fs-pBDD was also subjected to testing by cyclic voltammetry. The main reason for using this method was to determine the electrochemically active area, which contributed to the overall physicochemical characterization of this promising material. However, it was this step that brought into question the accuracy and precision of the calculation used. For this reason, the search for new ways to calculate the electrochemically active area of the working electrode...
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Study of Electrochemical Insertion Cations to the Oxides of Transitive Metals
Svoboda, Vít ; Kadlec, Jaromír (referee) ; Trnková, Libuše (referee) ; Kazelle, Jiří (advisor)
Electrochromic devices are based on the intercalation processes to the active layer mostly WO3. The optical properties of active layer are changed by intercalation ions from the electrolyte. For that purpose are used Li ions. The mass of thin layer can be observed by the QCM method. This method is based on the changes of the resonance frequency of a quartz crystal resonator. The investigated substance is deposited on the surface of the resonator. Various metals (Pt, Au, Ag) and their compounds should be plated on the resonator. Most frequently, the resonators for the frequency 5,0 MHz are used. This frequency change is used for the detection of chemical changes of the electrode surface and is very sensitive.
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Materials for Supercapacitors
Dvořák, Petr ; Paidar,, Martin (referee) ; Trnková, Libuše (referee) ; Sedlaříková, Marie (advisor)
This dissertation deals with the electrode materials, liquid and gel electrolytes suitable for supercapacitors. In the field of electrode materials were investigated carbon materials based on carbon blacks, expanded and micronized graphite suitable for supercapacitors working on the principle electrochemical double layer. Another area which this thesis deals with are aprotic liquid electrolytes prepared from suitable types of salts and aprotic solvents. The last part is focused on the preparation and subsequent electrochemical characterization of gel polymer electrolytes in order to increase the ionic conductivity of these electrolytes.
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Nanopatterned alumina-based materials for electrochemical sensors and biosensors
Kynclová, Hana ; Hynek, David (referee) ; Trnková, Libuše (referee) ; Prášek, Jan (advisor)
The doctoral thesis is focused on basic research and development of nanostructured surfaces prepared using anodic alumina material. Various types of gold nanostructured surfaces and nanoporous aluminum membranes for electrochemical sensors and biosensors were prepared using the anodic oxidation method. Nanostructured surfaces were prepared by electrochemical anodization of aluminum material to form hexagonally arranged nanopores. Gold was then deposited into the nanoporous masks by electrochemical reduction from potassium dicyanoaurate solution using a pulse deposition method. The prepared nanostructured gold surfaces were electrochemically characterized by electrochemical impedance spectroscopy and voltammetry. Temperature stability and the effect of annealing on their electrochemical behavior at atmospheric pressure as well as in the vacuum were investigated. Then, gold nanostructures of various dimensions were prepared and the influence of their shape and dimensions on the electrochemical behavior was studied. Nanostructured surfaces were also modified with 11–mercaptoundecanoic acid, and the effect of this modification on the electrochemical results was studied. In the last part of the work, nanoporous aluminum membranes were prepared, and their permeability was studied.
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Study of Metal Oxides and Hydroxides in Aqueous Solutions
Špičák, Petr ; Trnková, Libuše (referee) ; Kadlec, Jaromír (referee) ; Kazelle, Jiří (advisor)
This dissertation work deals with analysis of nickel hydroxide phases, their oxidation compounds, their stability and degradation mechanisms of electrochemically more active alpha phase on standard beta phase. The active material was prepared by both methods, electrodeposition and chemical precipitation. Main analysis method was Electrochemical Quartz Crystal Microbalance in combination with common analytical methods (cyclic voltammetry, potenciometry) can resolute between alpha and beta phases and quantitatively describe differences in main reaction by monitoring mass changes in the active material. Poor stability of the ?-Ni(OH)2 were improved by adding cations with valence two three and four into the structure instead of Ni atoms. The most important role plays cobalt and its hydroxide. Totally new way is to use titanium in combination with other cations. In electrolyte the most significant addition is LiOH, which has beneficial influent on cycle ability, stability in strong alkaline medium and cycle life.
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Preparation Techniques and Characterization of Electrodes with Nanostructured Surface
Hrdý, Radim ; Trnková, Libuše (referee) ; Janderka,, Pavel (referee) ; Hubálek, Jaromír (advisor)
Nowadays, nanostructures fixed on solid substrates and colloidal nanoparticles permeate through all areas of human life, in area of sensors and detection as well. This dissertation thesis deals with the fabrication of nanostructures on the surface of planar electrodes via self-ordered nanoporous template of aluminum trioxide. The nanofabrication, as one of many possible techniques, is used to increase the active surface area of electrodes by creating unique surface types with specific properties. These electrodes are very perspective in the applications, such as biomolecules electrochemical detection and measurement. The transformation of aluminum layer into non-conductive nanoporous template in the process of anodic oxidation is a fundamental technique employed to obtain the array of nanostructures in this thesis. The fabrication of high quality nanoporous membranes with narrow pore size distribution on various types of metallic multilayers is one of the key experimental parts in this work. Several problems associated with the production of the thin-film systems, including the dissolving the barrier oxide layer, are discussed and solved. Another part of this work deals with the use of nanoporous membrane as a template for the production of metallic nanostructures via electrochemical metal ions deposition directly into the pores. The obtained nanostructures as nanowires, nanorods or nanodots are characterized by the scanning electron microscopy and energy-dispersive or wavelength X-ray spectroscopy. The electrode surface, modified by gold nanostructures suitable for the detection of biomolecules, has been chosen for the electrochemical measurements, due to the gold biocompatibility. The nanostructured electrodes were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The effect of nanostructured surface geometrical parameters, including the size of the electrochemically active area, on the results of electrochemical measurements has been observed and compared to flat gold electrodes. Two model biomolecules, namely guanine and glutathione, have been chosen for the study of potential application of these nanostructures in biosensors.
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Study of Genotoxicity of Organic Compounds Using DNA Biosensors
Augustín, Michal ; Vyskočil, Vlastimil (advisor) ; Trnková, Libuše (referee) ; Labuda, Ján (referee)
Proposed dissertation thesis presents novel hybrid electrochemical DNA biosensors based on distinct forms of pyrolytic graphite ("edge-plane" and "basal-plane") and their potential in terms of applicability in the field of DNA electrochemistry. Testing of the applicability of the presented bioanalytical tools was preceded by thorough optimization process involving selection of the optimal values for the most crucial operational parameters of the electrochemical DNA biosensors fabricated by means of electrostatic adsorption - deposition potential (Edep), deposition time (tdep), optimal DNA concentration for electrostatic adsorption (cg(DNA)), and possible involvement of convection during the adsorption procedure. Initially, applicability of presented bioanalytical tools was investigated in relation to monitoring DNA damage by utilization of triplet of external DNA damaging sources - UV light irradiation, one- electron oxidants, and hydroxy radicals. Outcome of the damaging processes was monitored directly (via monitoring changes in the redox signals of DNA) or indirectly (via monitoring changes in the redox signals of redox indicator) by the use of voltammetric methods - square- wave voltammetry (SWV), cyclic voltammetry (CV), linear-sweep voltammetry (LSV), and electrochemical impedance...
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Novel Approaches in Electrochemical Determination of Xenobiotic Compounds and in Study of Their Interaction with DNA
Hájková, Andrea ; Vyskočil, Vlastimil (advisor) ; Trnková, Libuše (referee) ; Labuda, Ján (referee)
Presented Ph.D. Thesis is focused on the development of analytical methods applicable for determination of selected xenobiotic compounds and for monitoring DNA damage they can induce. The main attention has been paid to the development and testing of non-toxic electrode materials for preparation of miniaturized electrochemical devices and novel electrochemical DNA biosensors. 2-Aminofluoren-9-one (2-AFN) was selected as a model environmental pollutant, which belongs to the group of hazardous genotoxic substances. Its carcinogenic and mutagenic effects may represent a risk to living and working environment. 2-AFN has one oxo group, where the cathodic reduction occurs, and one amino group, where the anodic oxidation occurs. The voltammetric behavior of 2-AFN in the negative potential region was investigated at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) representing a non-toxic and more mechanically robust alternative to mercury electrodes. This working electrode was subsequently used for the development of a newly designed miniaturized electrode system (MES), which has many benefits as the possibility of simple field measurements, easy portability, and the measurement in sample volume 100 µL. Moreover, a glassy carbon electrode (GCE) was used for further investigation of...
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Development of Novel Electrochemical Methods Using Various Membrane Materials for Monitoring of Selected Anticancer Drugs and Phytochelatins
Skalová, Štěpánka ; Barek, Jiří (advisor) ; Labuda, Ján (referee) ; Trnková, Libuše (referee)
Present Ph.D. Thesis is focused on the development of electrochemical methods for determination of anticancer drugs using various types of membranes for their preliminary separation. Furthermore, this Thesis reports the study of transport mechanisms of heavy metals in the presence of phytochelatins across biological membranes. Sodium anthraquinone-2-sulphonate (AQS) was used as a model compound for its similar structure with anthraquinone-based (AQ-based) anticancer drugs (doxo/daunorubicin) and also due to its better availability. All these compounds can be easily electrochemically oxidized and/or reduced. Redox behaviour of AQS was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in a cathodic region on mercury meniscus modified (m-AgSAE) and polished silver solid amalgam (p-AgSAE) electrodes, Obtained results were used for the development of a micro-volume voltammetric cell (MVVC). Its applicability for voltammetric determination of anticancer drugs was verified by using doxorubicin (DX) as a model substance. The second part of this Thesis deals with therapeutic monitoring of anticancer drugs in the blood circulation of the patients. For pilot experiments, a liquid-flow system with dialysis catheter and amperometric detection was used. The flow rate of carrier...
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