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...

Presented Ph.D. Thesis is focused on the use of the boron-doped diamond (BDD) electrodes for voltammetric and amperometric determination of selected nitrophenols: 2-nitrophenol (2NP), 4-nitrophenol (4NP), and 2,4-dinitrophenol (2,4DNP). These compounds are listed as "priority pollutants" by United States Environmental Protection Agency (US EPA) due to their negative impact on living organisms and are mainly used in agriculture as plant growth stimulators. BDD electrodes are used for determination of wide range of electrochemically both reducible and oxidisable organic compounds and have become a popular electrode material thanks to its commercial availability and excellent mechanical and electrochemical properties. A differential pulse voltammetric method was developed for the determination of 2NP, 4NP and 2,4DNP at a BDD film electrode using electrochemical reduction and of 4NP and 2,4DNP using electrochemical oxidation. The method was successfully applied for the direct determination of these compounds in drinking and river water in the concentration range from 4×10-7 to 2×10-5 mol.L-1 . To improve the limit of quantification, a preconcentration by solid phase extraction from 100 mL (drinking and river water) and 1000 mL (drinking water) of water samples was used with limit of determination...

Presented dissertation thesis is focused on the development of electrochemical methods for the determination of three important tumour biomarkers, namely homovanillic acid (HVA), vanillylmandelic acid (VMA), and 5-hydroxyindole-3-acetic acid (5-HIAA). First part of the study is focused on electrochemical behaviour of these analytes in batch arrangement using differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). It has been proved that presented method is sufficiently sensitive for monitoring above mentioned analytes. Moreover, it can be used for determination of HVA and VMA in mixture. Obtained limits of detection (LODs) were 0.24 µmol·L-1 for HVA, 0.06 µmol·L-1 for VMA, and 0.12 µmol·L-1 for 5-HIAA. The requirements to speed up the analysis and at the same time to reduce its price initialized our study of the determination of tested biomarkers in flow systems. Firstly, flow injection analysis with amperometric detection was investigated for the determination of all three biomarkers at the same SPCE, and then an analogous determination of structural more similar pair, HVA and VMA, was performed at a boron doped diamond electrode (BDDE). Obtained LODs of optimized methods were as follows: at SPCE 0.07 µmol·L-1 for HVA, 0.05 µmol·L-1 for VMA, and 0.03 µmol·L-1 for 5-HIAA,...

In this work, the application of boron-doped diamond electrodes with various surface pre- treatment were tested on selected oxidizable and reducible model compounds, specifically para and ortho cresols and 2'-deoxycytidine and 7-deazaadenosine labeled by 4-nitrophenyl triazole. The aim of the study was the investigation of electrochemical and adsorptive processes with respect to the development of electroanalytical methods of detection of the selected compounds, or utilization of boron-doped diamond electrodes as detectors in liquid-flow systems. Cresols were used as the model oxidizable compound. On O-terminated and polished boron- doped diamond electrodes, cresols provide oxidation signal owing to their oxidation to methylphenoxy radical at comparable potentials as on other carbon-based electrodes used as a reference in this work, i.e., glassy carbon electrode, pyrolytic graphite electrode, and carbon paste electrode. These carbon electrode materials show relatively high propensity to adsorption of reaction products, while such adsorption is minimal on boron-doped diamond. In situ anodic activation allows for a rapid regeneration of boron-doped diamond surface prior to each scan. A differential pulse voltammetric method that was developed with a detection limit of 0.61 mol∙l-1 to 2.97 mol∙l-1...

1 Abstract Diamond is a unique material for its physical and chemical stability. However, many advance applications rely on surface functionalisation. Here, two types of diamond were modified on the surface - thin layer of chemical vapor deposition (CVD) and nanodiamond particles (NDs) high pressure and high temperature (HPHT). The aim of CVD surface modification was to prepare photosensitised, conductive, diamond electrodes for dye sensitized solar cells (DSSC). For this purpose, a thin diamond layer doped with boron was deposited on the silicon wafer. Boron doping provided p-type (semi)conductivity to diamonds. The surface of the diamond was hydrogenated with H-plasma, and a short carbon linker with a protected amino group was UV-photografted to the surface. In another study, a photoconverting dye (P1) was covalently attached to the amine-linker. Furthermore, a dye designed based on donor-π-acceptor (D-π-A) concepts was attached to the surface. Finally, a systematic study was done for differently conductive diamond layer and the underlying silicon wafer These experiments gradually lead to the highest ever reported photocurrents of 6.6 µA cm2 for a flat photosensitised boron-doped-diamond (BDD) electrode. Monomolecular layer surface functionalizations on CVD diamond are difficult to detect or even quantify...

We focused on a non-cooling room temperature microbolometer infrared imaging array device which includes a sensing layer of p-type a-Si:H component layers doped with boron. Boron incorporation and bonding configuration were investigated for a-Si:H films grown by plasma enhanced chemical deposition (PECVD) at varying substrate temperatures, hydrogen dilution of the silane precursor, and dopant to silane ratio using multiple internal reflection infrared spectroscopy (MIR-IR). This study was then confirmed from collaborators via Raman spectroscopy. MIR-IR analyses reveal an interesting counter-balance relationship between boron-doping and hydrogen-dilution growth parameters in PECVD-grown a-Si:H. Specifically, an increase in the hydrogen dilution ratio (H2/SiH4) or substrate temperature was found to increase organization of the silicon lattice in the amorphous films. It resulted in the decrease of the most stable SiH bonding configuration and thus decrease the organization of the film. The new chemical bonding information of a-Si:H thin film was correlated with the various boron doping mechanisms proposed by theoretical calculations. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. This is due to defects and a higher copper content at the grain boundary. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used to measure corrosion current and potential. Hydrogen gas evolution was also observed (for the first time) in Cu/Al bimetallic interface in areas of active corrosion. Mechanistic insight that leads to effective prevention of aluminum bond pad corrosion is explored and discussed. (Chapter 4) Aluminum bond pad corrosion activity and mechanistic insight at a Cu/Al bimetallic interface typically used in microelectronic packages for automotive applications were investigated by means of optical and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemistry. Screening of corrosion variables (temperature, moisture, chloride ion concentration, pH) have been investigated to find their effect on corrosion rate and to better understand the Al/Cu bimetallic corrosion mechanism. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. The corrosion starts as surface roughening which evolves into a dendrite structure and later continues to grow into a mud-crack type corrosion. SEM showed the early stage of corrosion with dendritic formation usually occurs at the grain boundary. This is due to defects and a higher copper content at the grain boundary. The impact of copper bimetallic contact on aluminum corrosion was explored by sputtering copper microdots on aluminum substrate. Copper micropattern screening revealed that the corrosion is activated on the Al/Cu interface area and driven by the large potential difference; it was also seen to proceed at much higher rates than those observed with bare aluminum. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used to measure corrosion current and potential. Hydrogen gas evolution was also observed (for the first time) in Cu/Al bimetallic interface in areas of active corrosion. Mechanistic insight that leads to effective prevention of aluminum bond pad corrosion is explored and discussed. Micropattern corrosion screening identified hydrogen evolution and bimetallic interface as the root cause of Al pad corrosion that leads to Cu ball lift-off, a fatal defect, in Cu wire bonded device. Complete corrosion inhibition can be achieved by strategically disabling the mutually coupled cathodic and anodic reaction cycles.