Preparation of poly(azure B) and graphene/azure B thin films for investigation of NADH amperometric sensor properties

In this Ph. D. thesis, two different studies were carried out. In the first study, electrochemical polymerization of Azure B (AB) on gold (Au) substrates was studied. The effect of pH and upper potential on the mechanism of formation of poly(AB) at Au substrates were investigated. For the electropolymerization of AB, nucleation and growth mechanisms were theoretically determined by using current density-time (j-t) curves. Various techniques were performed for the structural, morphological and optical characterization of poly(AB) thin films. It was determined that the best electrochemical polymerization of AB on gold substrates occurred in the pH 7.0 phosphate buffer solution (PBS) at 1000 mV potential. The j-t curves showed that formation of polymeric film started with random-type adsorption and continued with a regular nucleation and growth mechanism. In the second study, various electrode materials were designed by using drop-casting technique. For this purpose, Au(111) surface was immobilized with electrochemically (e-GO) and chemically (k-GO) fabricated graphene oxide and their composites of AB and these electrodes were performed for the amperometric determination of NADH. Many advanced techniques were used for the characterization of the prepared materials. e-GO/AB/Au(111) electrode was selected as the most suitable material for NADH determination. It was observed that the e-GO/AB/Au(111) electrode revealed linear range of 0.5-508 μM, sensitivity of 0.51 μAμM-1cm-2 and dedection limit of 0.15 μM. It was determined that the e-GO/AB/Au(111) biosensor was suitable for stability, sequential usage, real sample analysis and reproducibility of fabrication.