Study On Electrochemical Sensing Based On Graphene Composites And Gold Nanoparticals

Graphene?Gr?and noble metal nanoparticles were often employed for the preparation of electrode modification materials?EMM?because of their perfect catalytic activity,conductivity and biocompatibility.In this thesis,we mainly used graphene and gold nanoparticles to build electrochemical sensors,and study systematically the performance of the electrochemical sensors.Firstly,we studied EMM composed of reduced graphene oxide?rGO?and gold nanoparticle?AuNPs?.The self-assembled multilayers of rGO with AuNPs were made directly via electrostatic interaction on the surface of the GCE.After that,the modified GCE was used to construct the H₂O₂ electrochemical sensor.Structure and morphology of the layered materials were investigated using various characterization methods.Electrochemical performance of the sensor were investigated by electrochemical detection methods.The limit of detection was 37 nmol/L and the concentration range was 1.2 600 ?mol/L.Compared with that H₂O₂ sensor constructed by GN/Au-NPs composites,the detection limit is slightly smaller.To further improve the sensitivity of the EMM,we made molybdenum disulfide-rGO?MoS2-rGO?composite to form thin films with AuNPs.The MoS2-rGO was made by hydrothermal synthesis process.Finally the new EMM modified GCE was used to detect H₂O₂.Structure and morphology of the materials were investigated using various characterization methods.Electrochemical performance of the sensor was investigated by electrochemical detection method.The results showed that the limit of detection was 3 nmol/L and the concentration range was 2.6⁸00 ?mol/L.Higher sensitivity and lower detection limit were observed with the new EMM modified GCE compared with first EMM.In the end,we applied the successful EMM from the second study to construct electrochemical biosensor for thedetection of DNA.The detection of target DNA was realized by monitoring the electrical signal of the methylene blue as double helix indicator.The results showed that the limit of detection was 7.2 fmol/L in the concentration range of 0.01¹00 pmol/L.