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Carbon - based electrodes: From detection of biologically significant compounds to application in neurodegenerative diseases
Jarošová, Romana ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee) ; Navrátil, Tomáš (referee)
CARBON BASED ELECTRODES: FROM DETECTION OF BIOLOGICALLY SIGNIFICANT COMPOUNDS TO APPLICATION IN NEURODEGENERATIVE DISEASES By Romana Jarošová Carbon is a truly remarkable element that is essential to life on Earth, and its unique properties have made it an indispensable component in an astonishingly diverse array of applications. Whether serving as a fuel source or as a key component in electronic devices, carbon's ability to exist in different forms, each with their distinct physical and chemical properties, contributes to its widespread and continued use. Electrode production is one of the areas where carbon found its significant use. This thesis represents a unique combination of fundamental and applied electrochemistry using carbon-based electrodes. It explores a wide range of topics, from evaluating electrode microstructure as a critical factor affecting its electroanalytical behavior, to the use of carbon- based electrodes in Alzheimer's disease (AD) research. The first part of this Thesis focuses on the electrochemical performance of carbon-based electrodes with distinct microstructures. Specifically, this section discusses two novel electrode materials: boron-doped diamond and nitrogen-incorporated tetrahedral amorphous carbon. The microstructure of each electrode was investigated, and the...
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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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Voltammetric Determination of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol on a Screen-Printed Carbon Electrode
Jančová, Jana ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
The aim of the presented Master Thesis was to study an electrochemical behaviour of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) resulting in the founding of optimum conditions for their voltammetric determination at a screen-printed carbon electrode (SPCE) using DC voltammetry (DCV) and differential pulse voltammetry (DPV). Voltammetric behaviour of both compounds was investigated in dependence on the pH of the medium (realized using Britton-Robinson buffer). The optimum pH for the voltammetric determination of 2,4-D on the SPCE was chosen to be pH 5,0 for both voltammetric techniques, and, for 2,4-DCP, it was chosen to be pH 6,0 for both voltammetric techniques. The determination of 2,4-D at a concentration of 1·10-4 μmol·L-1 showed good repeatability for both voltammetric techniques used (1.3% for DCV and 0.7% for DPV), and, for 2,4-DCP, it showed acceptable repeatability for both voltammetric techniques used (1.3% for DCV and 4.8% DPV). Under optimum conditions, the calibration dependence of 2,4-D was measured for DCV in the concentration range of 10-100 μmol·L-1 , with limit of quantification (LOQ) of 1.0 μmol·L-1 and limit of detection (LOD) 0.3 μmol·L-1 . Under optimum conditions, the calibration dependence of 2,4-D was measured for DPV in the concentration range...
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Characterization of Electrochemical Behaviour and Adsorption of Methyl Viologen on Boron Doped Diamond Electrodes Depending on Their Surface Pre-treatment
Fořtová, Lucie ; Fischer, Jan (advisor) ; Vyskočil, Vlastimil (referee)
In this study we focused on the electrochemical and adsorptive behaviour of methyl viologen on electrode of boron doped diamond (BDD) possessing different termination as result of electrochemical or mechanical pretreatment. Namely was performed anodic activation applying +2.4 V in 0.5 mol L-1 sulphuric acid and cathodic pretreatment in the same solution at -2.4 V to obtain predominantly H-terminated surface. While the O- terminated surface is relatively hydrophilic with low surface conductivity, the H-terminated surface is hydrophobic with certain surface conductivity, which results typically in faster heterogenous electron transfer (HET) kinetics. Fast HET kinetics was observed on polished surfaces, that were obtained by polishing with alumina suspension. Methyl viologen (MV), a widely used herbicide, was used as a model compound because its quasireversible redox transformations result in charge changes of the molecule which includes neutral (MV0 ) or positively charged (MV+ , MV2+ ) forms. Adsorption was connected with MV0 form. The pilot experiments were performed in aqueous media using cyclic voltammetry (CV). The results indicate that adsorption of MV occurs not only on H-terminated surface, but also on the polished and O-terminated surface. Adsorption of MV0 was observed on anodic peaks on...
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Polarographic Determination of Genotoxic 2-Amino-9-fluorenone
Hájková, Andrea ; Vyskočil, Vlastimil (advisor) ; Dejmková, Hana (referee)
of Bachaleor Thesis The aim to this work was to find the optimum conditions for polarographic determination of genotoxic 2-amino-9-fluorenone (2-AFN) that can negatively affect the living and working environment. Foremost, the stability of 2-AFN stock solution in methanol was monitored using UV-VIS spectrophotometry and an optimal ratio of buffered aqueous and methanolic phase was found out for following polarographic measurements at a classical mercury dropping electrode (DME). The dependence of polarographic behavior of 2-AFN (of concentration 1×10-4 mol dm-3 ) on pH of analyzed solution was measured using DC tast polarography (DCTP) and differential pulse polarography (DPP) in the pH range 1.9 - 12.8, in the medium of Britton-Robinson (BR) buffer - methanol (9:1). The mechanism of polarographic reduction of electrochemically reducible oxo group at 2-AFN has been proposed on the basis of thus observed behavior. The optimum medium of BR buffer pH 4.0 - methanol (9:1) has been chosen for both polarographic techniques. The concentration range from 1×10-6 to 1×10-4 mol dm-3 was measured using DCTP at DME and from 1×10-7 to 1×10-4 mol dm-3 using DPP at DME. Reached limits of quantification (LQs) were 5×10-7 mol dm-3 and 1×10-7 mol dm-3 for DCTP at DME and DPP at DME, respectively. For comparison, the...
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Testing of Polished Silver Solid Amalgam Composite Electrode for Voltammetric Determination of Environmental Pollutants
Dědík, Jan ; Vyskočil, Vlastimil (advisor) ; Nesměrák, Karel (referee)
The aim of this study was the finding of applicable conditions for the determination of selected model environmental pollutants, namely 5-nitrobenzimidazole and picric acid, using DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished silver solid amalgam composite electrode (p-AgSAE-CE) in the aqueous solution of Britton-Robinson (BR) and finding of the limit of quantification (LQ) for these substances. For 5-nitrobenzimidazole, the optimum conditions of voltammetric determination have been found in the medium of B-R buffer pH 5, but any calibration dependences were obtained. The reason was the deteriorating quality of 5-nitrobenzimidazole response even if the routine pretreatment of working electrode was maintained. This resulted in obtaining of irreproducible results upon the determination of 5-nitrobenzimidazole. For picric acid, the optimum conditions have been found for both DPV and DCV at p-AgSAE-CE in the medium of B-R buffer pH 2. The concentration dependences were measured in the range 1.10-6 - 1.10-4 mol.L-1 for DPV with the value of reached LQ 2,5.10-7 mol.L-1 and, for DCV, in the range 1.10-7 - 1.10-4 mol.L-1 with LQ calculated as 5,5.10-8 mol.L-1 . For comparison of newly developed voltammetric methods of picric acid determination, a UV-VIS spectrophotometric...
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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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Voltammetric Determination of DNA Damage Caused by Genotoxic 2-Aminofluorene at a Carbon Film Electrode
Faťarová, Mária ; Vyskočil, Vlastimil (advisor) ; Zima, Jiří (referee)
A large-surface carbon film electrode (ls-CFE) represents a suitable alternative to the commercially available disposable screen-printed carbon working electrodes. Its simple, fast and inexpensive preparation, simple mechanical renewal of the electrode surface (by wiping off the old film with filter paper and forming a new one), good repro- ducibility of measurements, elimination of problems connected with "electrode history" and simple chemical modification are its main advantages. In this Bachelor Thesis, the utilization of ls-CFE for the preparation of a simple elec- trochemical DNA biosensor for the detection of carcinogenic environmental pollutant, 2-aminofluorene (2-AF), is presented. The composition of carbon ink suspension was optimized and tested using a Fe(II)/Fe(III) redox system by cyclic voltammetry (CV). A large-surface solid electrode, covered by a carbon film of the optimum composition, was then used as a transducer for the preparation of double stranded DNA (dsDNA) based electrochemical DNA biosensor (dsDNA/ls-CFE). The electrochemical behavior of dsDNA (i) present in the measured supporting electrolyte (0.1 mol.L−1 acetate buffer of pH 4.7) or (ii) attached at the ls-CFE surface (by covering with dsDNA stock solution and leaving to dry) was investigated using square wave voltammetry...
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Voltammetric Determination of Genotoxic Nitrobiphenyls
Horáková, Eva ; Vyskočil, Vlastimil (advisor) ; Navrátil, Tomáš (referee)
The presented diploma thesis is devoted to study of determination of 4-nitrobiphenyl (4-NBP) in model river water by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at m-AgSAE (diploma thesis relates to bachelor thesis, in it DCV and DPV methods for determination of 4-NBP in deionized water were developed). Limit of determination (LOD) is 2·10-7 mol·l-1 by DCV and 4·10-7 mol·l-1 by DPV. The adsorptive stripping DPV (AdSDPV) technique was tested to archive lower LOD the AdSDPV, optimal conditions were not found. Electrochemical behavior of 2-nitrobiphenyl (2-NBP) at m-AgSAE was studied. Optimal conditions for its determination by both techniques DCV and DPV were found in methanol-0,01 mol·l-1 LiOH (1:9) and in this medium peak current dependence in 1·10-7 mol·l-1 to 1·10-4 mol·l-1 2-NBP (LOD ≈ 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV) concentration range was measured. Developed methods were successfully tested for determination of 2-NBP in drinking and river water samples. For both mediums obtained LODs were 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV. AdSDPV technique was unsuccessfully tested to achieve lower LOD. Optimal conditions for simultaneous determination of 4-NBP and 2-NBP by DPV technique at m-AgSAE were found: methanol-0,25 mol·l-1 acetate buffer (pH = 6,0) 3:7....
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