Construction And Application Of Electrochemical Biosensors Based On Graphene Nanocomposites

The analysis of marine environment plays an important role for the research of marine ecosystem.Timely and effective analysis of marine environment provides scientific basis for the study of the marine ecosystem.In recent years,biosensors have attracted great attention due to their simple preparation techniques,portable features and cheap raw material,thus they have been widely used in various fields such as environmental detection,biomedicine,water online monitoring,etc.In this paper,the biosensor based on polyacrylonitrile(PAN)-polyaniline(PANI)-graphene(GRA)nanocomposite was constructed and was used to evaluate phenolic compounds in the sea water.The biosensor based on montmorillonite(MMT)-graphene(GRA)was constructed and the performance of the biosensor was studied.In addition,the polyaniline(PANI)-graphene(GRA)/platinum nanoparticles(PtNPs)glucose biosensor was constructed and it was successfully applied to the detection of glucose concentration.PAN-PANI-GRA nanocomposite was prepared by hybrid method and was used to construct polyphenol biosensor.The current responses of the biosensor based on PAN-PANI-GRA,PAN-GRA,PANI-GRA and GRA were compared.The surface morphologies of the material were characterized by scanning electron microscope(SEM).The electrochemical characteristics of the biosensor were characterized by cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).The results showed that the PANI-GRA/CS-PPO biosensor and GRA-PPO biosensor had current drifting,and the sensitivity of PAN-GRA/CS-PPO biosensor needed to be further improved.The addition of PAN could effectively modify the current drifting and the synergistic effect of PAN,PANI,and GRA could effectively improve the sensitivity of the biosensor.Under the optimal condition,the biosensor showed a high sensitivity of 6.46 A M-1cm-2 with a fast response time within 5 s,and the detection limit of the biosensor was 2.65×10-7M(S/N=3).The phenol compounds in water samples of Qiantang River and Niushan Island Sea were determined by standard addition method.The recoveries were in the range of 102%-106.7%,which showed that the biosensor could be used for the detection of phenolic compounds in water samples.Montmorillonite(MMT),a kind of caly,which has layer expansion in the presence of water molecules,presents high porosity,good absorption properties,and biocompatibility,thus effectively immobilizes enzyme and improves the stability of biosensors.This paper successfully inserted graphene(GRA)into montmorillonite and assembled polyphenol oxidase(PPO)into MMT-GRA nanocomposite.The MMT-GRA-PPO polyphenol biosensor was prepared by coating MMT-GRA-PPO on the glassy carbon electrode(GCE)and was treated with phase transfer method.The surface morphology and electrochemical performance of the biosensor were characterized.Under the optimal conditions,the liner range,sensitivity and detection limit of the biosensor were 0.2 ?M-52 ?M(R2=0.997),2.51?A ?M-1 cm-2,and 2.65×10-8 M(S/N=3:1)respectively.The biosensor combined good stability and biocompatibility of MMT,as well as the high conductivity of GRA,and was expected to be highly useful in the determination of phenolic compounds in water samples.The polyaniline(PANI)-graphene(GRA)/platinum nanoparticles(PtNPs)glucose biosensor was fabricated by depositing PtNPs on the PANI-GRA nanocomposite which was prepared by cyclic voltammetry.The biosensor showed a high sensitivity of 53.31 ?A mM-1 cm2,which was higher than the sensitivity of PANI-GRA glucose biosensor(22.1 ?A mM-1 cm-2).The linear range was 10.0 ?M-1.8 mM(R2=0.9997)and the detection limit was 1.19 ?M(S/N=3).The biosensor turning out with good repeatability,operation stability,and long-term stability was successfully applied to the determination of glucose concentration.