Glucose Biosensor Based On PPy And CNT/PPy Modified Carbon Paste Electrodes

Glucose is one of the most essential chemical substances in human body. When a total or partial lack of insulin happens, one will suffer from diabetes mellitus, characteristic of high glucose content in blood and urine. Diabetes is a disease threatening one's health severely. In order to keep the state of the illness on a satisfactory level, patients need frequently monitor or self-monitor some diabetic indices to judge whether the actual treatment is effective. Thus, being able to monitor glucose concentration in blood or sap expediently and accurately is very important for diabetics. Besides, glucose also exists extensively in medicament, foods, beverage, feeds and even the environment we lives. Therefore, glucose analysis and detection has great significance. So far, amperometic glucose sensor gains widely attention, because it has high selectivity, long-term stability, fast response, good sensitivity and accuracy, and great convenience.As a new type of macromolecule material, conductive polymer gains a lot of attention because of its excellent performance, and has been applied in the field of chemically modified electrodes. Polypyrrole is a typical conductive polymer and is also the most studied and used one. It has the advantages of convenient synthesis, needlessness of hard acidic and alkali condition, low electro-polymerizing potential, good stability in air, high mechanical strength, low cost, and great electronic transport, photo-electricity and thermoelectricity properties. In this dissertation, we developed an amperometic glucose sensor with outstanding performance by modifying the surface of screen-printed carbon paste electrodes with PPy film. We did a mass of experiments systematically to investigate the condition influence on the preparation of PPy-modified electrode, fabricated the sensor under the optimized condition, and measured various aspects of its performance. Our experimental results showed that the glucose sensor based on PPy modified carbon paste electrode had good linearity and sensitivity in a range of 5-25 mM under a work potential of 300 mV and a response time of 60s. Compared with the performance of the glucose sensor based on blank carbon paste electrodes, our sensor had larger response current and better selectivity, but inferior detection limit.Carbon nanotubes, as a promising material, has become a hot research spot due to its superior physical and mechanical properties, unique electronic transport property and good stability. Polymer-nanotube hybrid composites constitute a new class of nanomaterials, which could show properties characteristic of both constituent components with potential synergetic effects. We studied primarily the glucose sensor based on CNT/PPy composite modified carbon paste electrode. We found that the sensor had larger response current and better response grads.