Abstract
Biomedical diagnosis and testing are often accompanied by inefficiencies, including high-priced tests, high detection limits, and interference from other biologically relevant molecules. To overcome such inefficiencies, the construction of electrochemical sensors has attracted interest due to their promising nature. They are simple to fabricate, and they offer high sensitivity and selectivity and low detection limits. In this research work, aniline and some transition metals were used to form complex materials as tools in electrochemical biosensor fabrication. In general, cyclic voltammetric (CV), square wave voltammetric (SWV), and chronoamperometric techniques were employed to model the aniline metal complexes electrochemical reactivities on working glassy carbon electrodes. Fourier transformed infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Nuclear magnetic resonance (NMR), and Elemental analyzer (EA) were used for further characterization. Furthermore, the materials were employed for electrocatalytic detection of biologically active molecules. In this regard, aniline-based metal complexes of bismuth, nickel, and cobalt were synthesized, characterized, and applied for the electrocatalytic detection of biologically active molecules. The complexes were synthesized by a simple complexation method using aniline as a ligand. The as-prepared complexes were deposited on the glassy carbon electrode (GCE) using the drop and dry method and investigated as an electrocatalyst for the efficient and sensitive detection of dopamine, iodine, uric acid, and cysteine. The hybrid materials showed good voltammetric sensor application for the detection of biologically active molecules. The results indicated that the electrodes modified with the complex materials could detect micromolar concentrations of dopamine, iodine, uric acid, and cysteine. The bismuth aniline complex (BAC) indicated 12.3 μM and 23.17 μM low detection limits for dopamine and iodine, respectively. The nickel aniline complex (NAC) revealed a 2.09 μM limit of detection and a wide linear range of 2.5 μM-220 μM for cysteine detection. The cobalt-aniline complex (COAC) indicated 9.26 μM and 9.52 μM limit of detection for uric acid and dopamine respectively, with linear ranges of 20 – 280 μM and 10 – 200 μM. The developed sensors could eliminate the interference of other biomolecules such as ascorbic acid, glucose, and histamine, to mention a few. The sensors were only selective to the analytes of interest. The electrochemical sensors developed in this work demonstrate good potential for the molecular diagnosis of neurological disorders such as Parkinson’s disease.
Ph.D. (Chemistry)