<p>In this thesis, I present a simple, sensitive and low cost electrochemical nanobiosensor for quantitative determination of the herbicides glufosinate, glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Firstly, the nanostructured poly(2,5-dimethoxyaniline) (PDMA) materials were synthesized on gold electrode by the electrochemical &ldquo / soft template&rdquo / method using poly(4-styrenesulfonic acid) (PSS) as the dopant and structure-directing molecule. Fourier transform infrared (FTIR) spectroscopy, UV-Vis Spectroscopy, Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) studies inferred successful doping of the nanostructured PDMA film by PSS and that the template PSS directed the synthesis of both nanotubes and nanoparticles of PDMA with diameters less than 100 nm.</p>

<p>In this thesis, I present a simple, sensitive and low cost electrochemical nanobiosensor for quantitative determination of the herbicides glufosinate, glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Firstly, the nanostructured poly(2,5-dimethoxyaniline) (PDMA) materials were synthesized on gold electrode by the electrochemical &ldquo / soft template&rdquo / method using poly(4-styrenesulfonic acid) (PSS) as the dopant and structure-directing molecule. Fourier transform infrared (FTIR) spectroscopy, UV-Vis Spectroscopy, Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) studies inferred successful doping of the nanostructured PDMA film by PSS and that the template PSS directed the synthesis of both nanotubes and nanoparticles of PDMA with diameters less than 100 nm.</p>

Philosophiae Doctor - PhD / In this thesis, I present a simple, sensitive and low cost electrochemical nanobiosensor for quantitative determination of the herbicides glufosinate, glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Firstly, the nanostructured poly(2,5-dimethoxyaniline) (PDMA) materials were synthesized on gold electrode by the electrochemical "template"method using poly(4-styrenesulfonic acid) (PSS) as the dopant and structure-directing molecule. Fourier transform infrared (FTIR) spectroscopy, UV-Vis Spectroscopy, Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) studies inferred successful doping of the nanostructured PDMA film by PSS and that the template PSS directed the synthesis of both nanotubes and nanoparticles of PDMA with diameters less than 100 nm. / South Africa

The main objective of this work was to develop simple and sensitive electrochemical sensors for the detection of bisphenol A. To investigate the electrochemical behavior of BPA on a bare glassy carbon electrode. To apply the developed biosensor for the determination BPA by differential pulse voltammetry, electrochemical impedance spectrometry, square wave voltammetry and steady-state amperometry. To characterize the synthesized PDMA-PSS by cyclic voltammetry (CV), UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM).

The main objective of this work was to develop simple and sensitive electrochemical sensors for the detection of bisphenol A. To investigate the electrochemical behavior of BPA on a bare glassy carbon electrode. To apply the developed biosensor for the determination BPA by differential pulse voltammetry, electrochemical impedance spectrometry, square wave voltammetry and steady-state amperometry. To characterize the synthesized PDMA-PSS by cyclic voltammetry (CV), UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM).

Magister Scientiae - MSc / The main objective of this work was to develop simple and sensitive electrochemical sensors for the detection of bisphenol A. To investigate the electrochemical behavior of BPA on a bare glassy carbon electrode. To apply the developed biosensor for the determination BPA by differential pulse voltammetry, electrochemical impedance spectrometry, square wave voltammetry and steady-state amperometry. To characterize the synthesized PDMA-PSS by cyclic voltammetry (CV), UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM). / South Africa

Philosophiae Doctor - PhD / Immunosensors are affinity ligand-based biosensor solid-state devices in which the immunochemical reaction is coupled to a transducer. The specificity of the molecular recognition of antigens by antibodies to form a stable complex is the basis of the immunosensor on the electrode. The development of such a sensor requires a better design and preparation of an optimum interface between the biomolecules and the detector material. The immunosensors were developed based on Polyaniline derivative composite. Novel water soluble PdTe quantum dots (QD) was synthesized and characterized by different physical techniques such as UV-Visible (UV-VIS), Fluorescence Spectroscopy (PL), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The electroactivity of such synthesized quantum dots was studied by cyclic voltammetry in aqueous media. The synthesis of poly(2,5- dimethoxyaniline)-multi wall 'carbon nanotubes nanocomposite was carried out by electropolymerization in situ of 2,5-dimethoxyaniline - multi wall carbon nanotubes (PDMA-MWCNT) from aqueous dispersion containing acid-treated multi wall carbon nanotubes (MWCNT) and 2,5-dimethoxyaniline subsequently modifying a glassy carbon electrode in acid media. An undoped PDMA was also prepared for control. The composite for this work, consists of layer-by-layer method to form a multilayer film of QDs and PDMA-MWCNT. The method used was as follows; the drop coating of quantum dots followed by electrodeposition of poly(2,5- dimethoxyaniline )-carbon nanotubes onto surface of glassy carbon. The PDMA-CNT was characterized by UV-Visible (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The electrochemical characterisation of PDMA-CNT was carried out using cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The composite (QDs-PDMA-MWCNT) was also characterized using above mentioned techniques. The electrochemical immunosensor for fumonisin a mycotoxin was prepared by dropcoating of mycotoxins antibody onto the composite modified glassy carbon electrode. The response profiles of fumonisins sensors system were obtained from electrochemical impedance spectroscopy (EIS) measurements. The fumonisin immunosensor was used for the detection of fumonisins in certified com reference materials. For comparison reasons, analysis of such mycotoxins was carried out by using conventional analytical method enzyme-linked immunosorbent assay (ELISA). The EIS response of FBI immunosensor (GCEIPT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L-I and the corresponding sensitivity and detection limits were 0.0162 ka L ng-I and 0.46 pg L-I, respectively. Hence the limit of detection of GCEIPT-PDMA-MWCNT immunosensor for fumonisins in com certified material was calculated to 0.014 and 0.011 ppm for FBI, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FBI, FB2, and FB3) established by the Joint FAO / WHO expert committee on food additives and contaminants of 2 ug kg" and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2-4 mg L-I).