Enzymatic and Immunological Detection Principles for Environmental and Biological Applications

Sammanfattning: The aim of the thesis was to develop new analytical detection principles based on enzymatic and immunological reactions for sensitive, selective, cost-effective and high sample through-put detection devices. The thesis presents the basic elements and reaction paths necessary for the construction and development of enzyme based amperometric biosensors and immunoassays. The developed biochemical detection devices were utilised for the analysis of phenolic compounds, s-triazine herbicides, D-amino acids and interleukin-8. The thesis thus covers applications in both environmental and biological samples. D-amino acid biosensors were developed by co-immobilising D-amino acid oxidase and peroxidase into carbon paste electrodes. The detection principle is based on coupled reactions between the two enzymes. Various types of tyrosinase amperometric biosensors were developed for the analysis of mono- and di-phenolic compounds. An amplification of the overall signal is possible to achieve by the reduction of the enzymatically produced product at the electrode surface. Amplification factors and rate limiting steps of three different sensor configurations were investigated in order to further improve the sensitivity and stability of tyrosinase based amperometric biosensors. The developed tyrosinase biosensors were integrated on-line with sample handling and liquid chromatographic techniques for the analysis of phenolic compound in environmental as well as biological samples. An enzyme flow immunoassay technique for atrazine using b-galactosidase as the enzyme label and a cellobiose dehydrogenase (CDH) biosensor as the label detector was developed. The optimised system was applied to the analysis of atrazine in spiked surface water samples, by utilising both the CDH biosensor and colourimetric detection. A non-competitive flow immunoassay method was developed for the analysis of interleukin-8 in cell samples.