Development of amperometric biosensors based on conducting polymer

Biosensors play a very important role in medicine, agriculture, food, pharmacy, environment, and many industries such as defense, automation, and quality control. Simple and highly sensitive analyses are needed for compounds, particularly glucose, phenol derivatives, and urea, which are needed to be kept under control due to their adverse effects on human health. In addition to their high specificity, biosensors have other advantages such as the possibility of direct measurement in colored or cloudy solutions in a wide concentration range. Even though there are many studies in literature about the use of conductive polymers in amperometric biosensors, intensive studies have been carried out for the production of new biosensors since the important characteristics of the existing sensors such as selectivity, sensitivity, linear range, stability, detection limit, and shelf life are not good enough for current commercial applications. Recent studies have shown that designing biosensors with advanced properties involves use of new polymer matrices with appropriate characteristics. Poly (2,5-dithienylpyrrole) (PSNS) and polypyrrole (PPy) derivatives are promising, especially for electrochromic applications, as they have low oxidation potentials and can be easily synthesized by chemical and electrochemical methods. Despite these favorable properties, there is a limited number of studies on the use of PSNS derivatives as polymer matrices in enzyme biosensor applications. Additionally, the effects of the polymer structure on the biosensor characteristics have not been investigated systematically. For this thesis, we have synthesized Py-Fc and five different SNS derivatives (SNS-An, SNS-Et, SNS-N3, SNS-HE, and SNS-Fc). These monomers (except PSNS-N3 and PPy-Fc) were polymerized electrochemically and used as the electroactive layer in glucose biosensors. To investigate the effect of copolymerization, we electrochemically synthesized P(SNS-AN-co-EDOT) and utilized in a glucose biosensor. We also prepared urea and polyphenol biosensors by using PSNS-Fc and P(SNS-Fc-co-EDOT). The use of accelerators in the biosensor structure and the effect of the accelerator type were also investigated systematically in our studies. The appropriate preparation and working conditions were determined for each of the 21 different biosensors. Then, using chronoamperometry, the analytical performance of each biosensor was examined in terms of their analytical characteristics such as sensitivity, liner range, stability, lowest detection limit, and shelf life. Prepared biosensors were used for glucose, polyphenol, or urea detection in commercially available samples and/or samples obtained from a hospital central laboratory and the results were compared with the reference method.