The Sensitivity Enhancement Of Graphene Doped Molecular Imprinting Electrochemical Sensors For Uric Acid

Imprinted membrane-based electrochemical sensors, always suffers from thetroubles of highly selectivity but poor sensitivity. Owing to its unique2D structureand optical, electrical properties, catalytic properties, good biocompatibility,Graphene nanomaterials are aroused people’s interesting to their research fieldsespecially in the sensors, the graphene can significantly improve the sensitivity andresponse rate. In this paper, with the help of molecular imprinting technique, differenttypes of graphene and functional substrate chitosan to build a uric acid moleculeelectrochemical sensing interface with a specific identification property. A series ofelectrochemical technique are used to investigate the electrochemical behaviours ofuric acid on different types of graphene sensors. Furthermore, the effect of variedgraphene which possess different fuctional group on the performance of imprintedfilms sensor were discussed, the main contents are as follows:Chitosan doped with graphene as a functional matrix, uric acid as the templatemolecules, chitosan-graphene uric acid complex was deposited onto the surface ofglassy carbon electrode by constant potential deposition technique, then the templateuric acid was eluted with potential induction method to form the uric acid moleculesimprinted sensor with spatial recognition sites. It was found that the doped grapheneimprinted sensor significantly improved the electrochemical responses for uric acid,under the optimized conditions, a five-fold increased in uric acid oxidation peakcurrent than that on the undoped imprinted sensor. The prepared imprinted sensor stillretain specific recognition to uric acid was embodied in the electrochemical responsesof structurally similar molecule on the MIP sensor is less than that on NIP sensor andthe interference is small while a certain concentration of coexistence exist, this resultindicates that doped nanoparticles in the imprinted membrane can improve thesensitivity and retain specific recognition for template molecule. To further study theimpact of the graphene structure on the imprinted sensor performance,electrochemical behavior of uric acid in the oxidation of the carboxyl graphene andgraphite alkene and chitosan composite imprinting system have investigated and theresults showed that these two types of graphene on the system did not show obvious electrochemical sensitizing effect.Scanning electron microscopy, infrared spectroscopy, ultraviolet spectroscopy,X-ray diffraction, AFM were applied to study the microscopic structure of grapheneand its derivatives on the sensor, the impact of physical and chemical properties, andexplores the impact of graphene in the composite system. Electrochemical techniqueswere used to the quantitative test in the reaction mechanism of uric acid on the sensor,graphene sensitizing effect of reasons, the results show that the graphene material caneffectively improve the sensing membrane electron transfer rate, large surface areagraphene cause the change of the chitosan surface morphology, and increase theelectrode surface area, therefore, the accumulation ability is enhanced and thedetection sensitivity improved.