Development of a new pencil graphite electrode-glucose oxidase based biosensor for determination of glucose

In this thesis, biosensors will be created using a variety of methods to pencil graphite electrode surface immobilization of glucose oxidase enzyme is intended. Biosensors for detection of glucose using glucose oxidase enzymes are generated. Firstly, glucose oxidase was crosslinked with gelatin and gluteraldehyde and fixed on the pencil graphite electrode surface. (PGE/Glucose oxidase-gelatin/ gluteraldehyde). Secondly, a different biosensor was designed. For this aim, biosensor was prepared by using nafiion. Glucose oxidase enzyme was fixed on pencil graphite electrode surface with nafion and gluteraldehyde. (PGE/Glucose oxidase /nafion/ gluteraldehyde). Glucose measurements were carried out at -0.7 V with amperometric method by developed biosensor systems. In optimization studies for designed biosensor, firstly, the optimal amount of enzyme, gelatin,optimal percentage nafion and optimum glutaraldehyde duration time were carried out. Optimization of working conditions; optimum pH and optimum temperature also investigated. Afterwards, in the characterization studies some paramaters such as linearity, repeatability, reproducibility, interference effects of some compounds and sample analyses were determined. From the optimization studies, amount of enzyme, gelatine amount and glutaraldehyde duration time were determined as 1.14U/mL, 20 mg and 3 minutes for the PGE/gelatine-glucose oxidase/glutaraldehyde modified biosensor. In optimum condition, buffer system is 50 mM, pH: 7.5 phosphate buffer and optimum temperature is 30°C. It was determined at the characterization studies on the PGE/gelatine-catalase/glutaraldehyde biosensor that linear results are obtained between the ranges of 50 µM to 1000 µM glucose concentration. Amount of enzyme, nafion rate and glutaraldehyde duration time were determined as 1.14U/ml, 1.5% and 5 minute for the PGE/nafion/glucose oxidase/glutaraldehyde modified biosensor. Phosphate buffer (50 mM; pH 7.5 ) and 30°C were established as providing the optimum working conditions. It was determined at the characterization studies on the PGE/nafion/glucose oxidase/glutaraldehyde biosensor that linear results are obtained between the ranges of 50 µM to 1000 µM glucose concentration.