Non-enzymatic Electrochemical Sensor Based On Graphene Nano-composites

As an important branch of sensors,electrochemical biosensor occupies an important position in researching of biosensors.It is widely used in the field of military,clinical medicine and environment analysis.Being affected of the rapid development of nanotechnology,nano-materials,with special physical and chemical properties,have great potential in the field of electricity and optics in recent years.Graphene?RGO?is a fascinating two-dimension nano-material.The discovery of graphene plays a role in promoting the development of electrochemical biosensor.In this article,two kinds of electrochemical non-enzymatic sensors were built based on RGO nano-composites and we have achieved several results as follows:1.Chitosan?CHIT?was employed to disperse RGO by stirring and ultrasonic method.Chloroauric acid was in-situ reduced to gold nano-particles?GNPs?in RGO-CHIT and then a stable dispersion of RGO-CHIT-GNPs was obtained.A non-enzymatic electrochemical sensor for H₂O₂ was constructed by electrodepositing PB-Au on RGO-CHIT-GNPs/Au.Cyclic Voltammetry?CV?and electrochemical impedance spectroscopy?EIS?method were employed to characterize the sensor.The experimental condition was optimized in terms of temperature and acidity of reaction liquid,amount of RGO,and the cylinder number of PB-Au depositing.Concentration of H₂O₂ in solution was measured by PB-Au/RGO-CHIT-GNPs/Au using a potentiometric method.The non-enzymatic sensor showed a wide linear range of 3.5×10^-9 M².2×10^-2 M?r=0.9975?,with a low detection limit of 3.5×10^-9 M,and 7 times can be reused at most.The sensor was used for detecting the spiked recoveries of H₂O₂ in actual samples of snow-water in range of 97%¹02%,and relative standard deviation?RSD?was about 1%.The sensor produced by laboratory with a wide linear range and lower detection limit.2.Two kinds of mercapto cobalt tetraphenyl porphyrin compounds?CoTMPP?were prepared by a Alder method.The RGO-CoTMPP composite was prepared by RGO and CoTMPP based on their?-?interaction.The structures of products were ascertained by UV,IR and FS.The effect of concentration of porphyrin and assembly time to the SAMs was investigated.The results showed that RGO-CoTMPP/Au had the greatest electrochemical properties only when the RGO-CoTMPP is 10 mg/L and n?CoTMPP?was two times of n?RGO?in the RGO-CoTMPP nano-composites.3.A non-enzymatic electrochemical sensor for glucose was fabricated by reducting of HAuCl₄ in situ on the surface of RGO-CoTMPP/Au.CV and EIS method were employed to characterize the sensor.The experimental condition was optimized in terms of electrolyte pH value and the amount of HAuCl_4.The results showed that sensor produced by laboratory had good selectivity and reproducibility,and 13 times can be reused at most.The sensor showed a wide linear range of 1.0×10^-66 M¹.0×10^-2 M?r=0.9911?,with a low detection limit of5.8×10^-7 M.The sensor was expected to be used for detecting blood glucose levels.