The Preparation Of A New Type Of Electrochemical Aptamer Sensor And Its Application In Food Safety Detection

Electrochemical aptasensor is a new generation of sensing technology that combines the fields of chemistry,physics,biology and electronics.Electrochemical aptasensor has broad application prospects in many fields such as bioanalysis,food inspection,environmental protection,and clinical testing.In recent years,with the continuous advancement of nanocomposites,the preparation of novel electrochemical aptasensor based on nanocomposites has made great progress.Hernin,the electrochemi-cal aptasensor was constructed based on large specific surface area,excellent electrical conductivity and and good biocompatibility of nanocomposites.The applications of electrochemical aptasensor were carried out as follows:1.An electrochemical aptasensor based on WS2-GQDs nanocomposites was developed and applied to the detection of malachite green(MG).The WS2-GQDs nanocomposites were fixed to the surface of the glassy carbon electrode(GCE),which enhanced the conductivity of the electrode and promoted the electron transfer rate.Gold nanoparticles(Au NPs)were synthesized using chloroauric acid and sodium citrate,and then the thiol-modified aptamers were immobilized on the Au NPs/GQDs-WS2/GCE modified electrode by Au-S bond to specifically recognize MG.The electrochemical aptasensor exhibited excellent sensitivity,selectivity and stability for detecting MG.The detection limit of MG was 3.38 n M and the linear ranged from 0.01 to 10μM.This paper also applied the sensor to the actual analysis of fish samples and fish pond water,and has obtained satisfactory results.2.An electrochemical aptasensor based on WS2-Ag NCs nanocomposites was developed and applied to the detection of ofloxacin(OFL).The WS2-Ag NCs nanocomposites were fixed to the surface of the glassy carbon electrode(GCE),which enhanced the conductivity of the electrode and promoted the electron transfer rate.Then the thiol-modified aptamers were immobilized on the Ag NCs-WS2/GCE modified electrode by Ag-S bond to specifically recognize OFL.The OFL/MCH/APT/Ag NCs-WS2/GCE modified electrode after the binding of the sample was incubated in the GQDs solution,and then the GQDs was combined with the aptamer by π-π stacking.Then the modified electrode was incubated in a Prussian blue(PB)precursor solution,and the PB precursor solution used GQDs as a support matrix to synthesize Prussian blue nanoparticles(PB NPs).Then the DPV was used to detect the electrochemical signal of PB NPs.With the increase of the concentration of OFL solution,the peak current of the PB NPs gradually decreased.The detection limit of OFL was 8.0p M and the linear ranged from 0.05 to 500 n M.This paper applied the sensor to the actual analysis of fish samples and chicken feed,and has obtained satisfactory results.3.An electrochemical aptasensor based on WS2-CQDs nanocomposites was developed and applied to the detection of sulfamethazine(SMZ).The WS2-CQDs nanocomposites were fixed to the surface of the glassy carbon electrode(GCE),which enhanced the conductivity of the electrode and promoted the electron transfer rate.The SMZ aptamer and the electrode surface were bonded to each other via an amino group and a carboxyl group.When the aptamer specifically bond to SMZ,the conformation of the aptamer changed,resulting in a decrease in the electrostatic binding of the cationic polymer polyethyleneimine(PEI)to the aptamer chain.Using hexaammine ruthenium(Ru Hex)as the electrochemical signal marker of the aptamer sensor,a signal-enhanced electrochemical aptasensor was established by electrostatic adsorption between Ru Hex and aptamer phosphate backbone.The detection limit of SMZ was 4.0p M and the linear ranged from 0.01 n M to 1.0μM.This paper applied this sensor to the actual analysis of milk samples and pork samples,and has obtained satisfactory results.