The Research On Enzyme Biosensor Based On Graphene For Detecting Pesticide Residues

To improve the production of various kinds of crops,pesticides are widely used.But the resulting problems of pesticide residues have caused harm to health.Therefore,in order to improve people?s life,we need develop the technology that is simple,rapid and sensitive to detect the pesticides.With the development of science and technology,enzyme biosensors have gained considerable attention thanks to the virtue of low cost,simple equipment,high sensitivity and low detection limit.The text has prepared three graphene-base composite materials as the electrode materials of biosensors based on enzyme inhibition for the detection of organophosphates and carbamates.The research contents and results include:(1)The sensitive electrochemical biosensor based on immobilization of acetylcholinesterase(AChE)on the electrochemically inducing porous graphene oxide network(e-pGON)was fabricated for detection of carbamate pesticides.The e-pGON effectively promotes the electron transfer rate and facilitates the access of substrates to the active centers.The biosensor of AChE-e-pGON/GCE was used to detect the carbaryl.Under optimum conditions,the inhibition of carbaryl is proportional to its concentration ranging from 0.3 to 6.1 ng/mL and the detection limit is 0.15 ng/mL.In real samples analysis,the biosensors exhibited a good accuracy for carbaryl sensing.(2)The biosensor AChE-e-PGON-MWCNTs/GCE based on immobilization of AChE on the electrochemically inducing porous graphene oxide network/multi-walled carbon nanotubes composites(e-pGON-MWCNTs)was achieved for detection of carbofuran and paraoxon pesticides.The biosensor exhibits a linear range from 0.03 to 0.81ng/mL for carbofuran,and the linear range from 0.05 to 1 ng/mL and from 1to 104 ng/mL for paraoxon.Furthermore,the detection limits for carbofuran and paraoxon can reach to 0.015 ng/mL and 0.025 ng/mL,respectively.(3)The mixed solution was prepared through electrostatic-interactions between positively charged PMMA latex and negatively charged GO.We prepared porous reduced graphene oxide(PRG)by removing the PMMA in high temperature treatment.And the biosensor of AChE-PRG/GCE can be used to detect the pesticides of carbofuran and paraoxon.Under optimum conditions,the inhibition of carbofuran is proportional to its concentration ranging from 0.004 to 0.18 ng/mL and the detection limit is 0.002 ng/mL.The inhibition of paraoxon is also proportional to its concentration ranging from 0.002 to 0.147 ng/mL,the detection limit is 0.001 ng/mL.