Fabrication And The Sensing Performance Of The Electrochemical Enzyme-sensors Based On Graphene

Graphene has a large specific surface area and great electron mobility, and itsderivatives contain a large number of boundary points, structural defects andfunctional groups, which is the ideal material for fabricating t he electrochemicalbiosensors. How to design and prepare graphene-based electrochemical sensors withexcellent performance have become an important new area of sensor field. In addition,the fast and efficient detection of glucose has become increasingly important becausediabetes is a common health problem worldwide, and is a murderer of initiating thedeath and disability. In this thesis, the graphene-based electrochemical biosensors werefabricated in three different ways aiming at the detection of gluco se. The affect of thethree different ways on the performance of produced sensors were systematicallyinvestigated. The main contents are as follows:(1) Preparation of GCE/RGO-CS/PtNPs/GOD-CS sensor and its performance.Graphene oxide was reduced with ascorbic acid to obtain graphene (RGO), it wasdispered in the polymer composite of chitosan. Then glassy carbon electrode (GCE)was modified with RGO/chitosan composites (RGO-CS). After that electrodeposited Ptnanoparticles (PtNPs) on the electrode surface, and covered the surface with glucoseoxidase (GOD)-chitosan composite to build sensors. The architecture of theperformance of the sensor were characterized in detail by UV-visible spectroscopy, IR,X-ray diffraction, scanning electron microscopy, cyclic voltammetry and impedancetesting. It’s found that the biosensor exhibits fast current response, a linear response toglucose over the range from0.01mmol·dm3to1.27mmol·dm3, a high sensitivity of30.57μA·mmol·dm3·cm2and good stability.(2) Preparation of GCE/RGO-PDA/GOD/PtNPs sensor and its performance.Graphene oxide was reduced with dopamine, and coated by polydopaminesimultaneously to form RGO-PDA composite. Then glassy carbon electrode (GCE)was modified with RGO-PDA composite. GOD was immobilized on the electrodesurface by covalent bond between the amino group and polydopamine. After thatelectrodeposited Pt nanoparticles (PtNPs) on the electrode surface to build sensors.The architecture of the performance of the sensor were characterized in detail byUV-visible spectroscopy, IR, Atomic force microscopy, X-ray diffraction, scanningelectron microscopy, cyclic voltammetry and impedance testing. It’s found that thebiosensor shows good stability, reproducibility and selectivity, with an examination rang from0.20mmol·dm3to1.0mmol·dm3, and a high sensitivity of30.57μA·mmol·dm3·cm2.(3) Preparation of GCE/ERGO-CS/PtNPs/GOD-CS sensor and its performance.Graphene oxide was mixed with chitosan to form GO-CS composites, and which wasused to modify glassy carbon electrode. After that GO was reduced electrochemically,then electrodeposited Pt nanoparticles (PtNPs) on the electrode surface, and coveredthe surface with glucose oxidase (GOD)-chitosan composite to build sensors. Thearchitecture of the performance of the sensor was characterized in detail by X-raydiffraction, scanning electron microscopy, cyclic voltammetry and impedance testing.It’s found that the biosensor detecte the glucose with a linear range from0.10mmol·dm3to1.0mmol·dm3and a high sensitivity of39.10μA·mmol·dm3·cm2.