Detection Of Malathion And Carbofuran Based On Acetylcholinesterase Biosensor

Organophosphorus pesticide and carbamate pesticide has been used in agriculture duing to their characteristics of high efficiency,broad spectrum,short residual time and so on,but they also have caused some serious threats to food safety and environmental protection because of being used excessively and unreasonably.Therefore,it is of great significance to establish a convenient,rapid and effective detection method for detecting organophosphorus and carbamate pesticides rapidly.Electrochemical acetylcholinesterase?AChE?sensor has the advantages of convenient,fast,low cost,miniaturization and so on,which make it have a great potential for detecting organophosphorus pesticide and carbamate pesticides rapidly and effectively.In this study,nitrogen-doped carbon ball?N-Cs?,nitrogen-doped carbon ball loading nanogold?N-Cs-Au?and Fe₃O₄@carbon spheres?Fe₃O₄@/Cs?were synthesized based on the advantages of carbon ball nanomaterials and Fe₃O₄ magnetic nanoparticles of high specific surface,good electrical conductivity,biocompatibility,adsorption et al.AChE sensors was constructed for the detection of Organophosphorus pesticide and carbamate pesticide.The main contents are as follows:1 Nitrogen-doped carbon nanocomposites was synthesized based on carbon ball and nitrogen element was introduced into carbon ball to improve its dispersibility.Glassy carbon electrode?GCE?was used as working electrode and AChE/N-Cs/GCE biosensor was constructed for detecting organophosphorus pesticide and carbamate pesticide with malathion and carbofuran as templates respectively.By adding N-Cs on the surface of GCE,the resistance is reduced by 30.29% and the oxidation peak current in 1.0 mmol/L ATCL increased by 66.99%,which show that that N-Cs can effectively promote the transfer of electrons,enhance the conductivity and improve the sensitivity of the electrodes.The amount of N-Cs and enzyme content were optimized,the result show that AChE/N-Cs/GCE sensors has a good sensitivity and catalytic activity in the condition of 3 ?L N-Cs and 0.2 U AChE.Under the optimized conditions,the biosensor was used to detected malathion and carbofuran,the linear range were 1.11�10-⁸³.50�10-⁶ g/L and 7.28�10-⁹².30�10-⁶ g/L respectively.The detection limits?calculated by inhibition rate of 10%?were 2.99�10-⁹ g/L and 5.92�10-⁹ g/L respectively.The recoveries were between 89.06¹02.3% and 91.45¹04.2% respectively,the precision was good.AChE and ATCL have a good affinity on the surface of AChE/N-Cs/GCE,and the Michaelis-Menten constant was 0.28 mmol/L.2 N-Cs-Au was compounded by loading AuNPS on the surface of N-Cs and the AChE/N-Cs-Au/GCE biosensor was constructed for detecting malathion and carbofuran.The results show that the resistance reduced by 32.38% and the oxidation peak current in 1.0 mmol/L ATCL increased by 85.86% when Au NPS was loaded on the surface ofN-Cs.The kind of crosslinking agent,the amount of modified N-Cs-Au and pH of PBS were optimized and the result show that AChE/N-Cs-Au/GCE biosensor has a good sensitivity and high rresponding current when 0.5%?Wt/V?chitosan was used as crosslinking agent,the amount of modified N-Cs-Au was 4 ?L,and pH 7.5 PBS was used as the supporting electrolyte solution.Under the optimized conditions,the biosensor was used to detected malathion and carbofuran,the linear range were 3.50�10-¹⁰¹.11�10-⁵ g/L and 2.30�10-¹⁰².30�10-⁵ g/L respectively.The detection limits?calculated by inhibition rate of 10%?were 5.99�10-¹¹ g/L and 6.76�10-¹¹ g/L respectively.the recoveries were between 92.10⁹8.55% and 91.41⁹5.85% respectively,and the biosensor has good anti-interference ability to common heavy metals Pb,Cu,Cd and Mn.3 Fe₃O₄@carbon sphere was synthesized by loading carbon sphere on the surface of Fe₃O₄ for remiting the agglomeration phenomenon of Fe₃O₄.The good conductivity,adsorption property and biocompatibility properties of Fe₃O₄ were used for constructing AChE/Fe₃O₄@Cs/GCE biosensor to detection malathion and carbofuran.The study show that compared with GCE,the resistance of Fe₃O₄@Cs/GCE reduced by 63.57% and the oxidation peak current of AChE/Fe₃O₄@Cs/GCE in 1.0 mmol/L ATCL increased by 197.8%.The concentration of chitosan,the amount of modified Fe₃O₄@Cs were optimized and the result show that AChE/Fe₃O₄@Cs/GCE biosensor has a good sensitivity and catalytic activity when 0.4%?Wt/V?of chitosan was used and the amount of modified Fe₃O₄@Cs was 4 ?L.Under the optimized conditions,the biosensor was used to detected malathion and carbofuran,the linear range were 1.55�10-¹0¹.55�10-⁵ g/L and 1.12�10-¹0¹.12�10-⁵ g/L respectively.The detection limits?calculated by inhibition rate of 10%?were 1.66�10-¹¹ g/L and 4.146�10-¹¹ g/L respectively.the recoveries were between 92.65⁹6.20% and 92.78¹03.7% respectively.The RSD of interclass and interblock were 1.75% and 3.65% respectively,the biosensor has a good repeatability.The oxidation peak current could be recovered to 91.84% after being inhibited when was activated by pralidoxime iodide for 10 min,the regeneration was good.Oxidation peak current could be maintained at the 92.35% of original level when be stored 30 d in 4 ?surroundings,the stability was better.