| In this thesis,a series of porous nanomaterials were prepared,and their large specific surface area and more active sites could be used to construct a variety of pesticide residue electrochemical biosensing interfaces.Investigate the effect of material size and morphology on sensor performance,and study active site and loading control methods.On the basis of the above research,determine the interface composition and construction method,optimize the measurement conditions,establish a highly sensitive analysis method for pesticide residues,establish a variety of pesticide residue analysis methods and carry out practical application research by optimizing the measurement conditions.The main contents include:1.Using the amino functionalized mesoporous dendritic fiber nano-silica?NH2-DFNS?as the DNA amplification platform and the current generated by the DNA as a sensing strategy,an electrochemical aptasensor for chlorpyrifos residues was established.The signal transduction and preparation steps of the aptasensor were greatly simplified,and the sensitivity of the aptamer sensor was improved.NH2-DFNS was prepared by a simple microemulsion method.This spherical nanomaterial with three-dimensional?3D?central radiation channels and graded pores carried a large amount of DNA,which could amplify the current signal generated by the DNA in the aptamer sensor.The sensor has good sensitivity for chlorpyrifos detection,linear range is 1.0 fM?1.0 nM,and detection limit is 0.43 fM.It was used for actual sample testing and the results are satisfactory.2.Based on Cu-MOF,a dual-signal electrochemical aptamer sensor was constructed for ultra-sensitive detection of acetamiprid.A large number of complementary strands?cDNA?of the acetamiprid aptamer chain were loaded into Cu-MOF with large specific surface area and layered pores.In the sulfuric acid medium,the phosphate group in the aptamer skeleton and sodium molybdate could undergo a redox reaction to generate a signal,which was output together with the electrochemical signal generated by Cu-MOF.This dual-signal output sensor not only broadened the application range of the aptamer in the sensor,but also could further increase the accuracy of detection.The detection range of the sensor we constructed for acetamiprid was:1.0?9?10-8?1.0?9?10-14 mol/L,detection limit 3.33 fM?Cu-MOF signal probe?;1.0?9?10-8?1.0?9?10-14 mol/L,detection limit 3.47 fM?DNA signal probe?.3.Based on Ce??,??-MOF,an electrochemical aptasensor was constructed for highly sensitive detection of malathion.The Ce?III?-MOF material was synthesized by hydrothermal method,and partially oxidized with NaOH and H2O2 to prepare the mixed valence Ce??,??-MOF material.Then modified AuNPs-Thi-AuNPs layer by layer,where Ce??,??-MOF not only served as a substrate to load more Thi,but also could be used to catalytically amplify Thi through the conversion of Ce?III??Ce?IV?,and finally achieved ultra-sensitive detection of malathion.The detection range of the constructed aptasensor for malathion was 10 fM?100 nM,and the detection limit was 4.45 fM.4.The aptamer sensor was constructed based on the mixed valence state Ce??,??-MOF for the simultaneous determination of malathion and chlorpyrifos.AuNPs-Thi-AuNPs and PEI-Fc-AuNPs were modified on the surface of Ce??,??-MOF.Amplified the signal by using Ce??,??-MOF with good catalytic performance to Thi signal tag for catalytic amplification and ascorbic acid?AA?for Fc catalytic sensitization.A highly sensitive electrochemical aptasensor for simultaneous determination of malathion and chlorpyrifos was constructed and the detection range of the sensor for chlorpyrifos was 1.0?9?10-6?1.0?9?10-13 mol/L?detection limit0.038 pM?,the detection range for malathion was 1.0?9?10-6?1.0?9?10-13 mol/L?detection limit0.045 pM?.The sensor provided a new idea for the simultaneous determination of multiple components,and had high application prospects in the field of food safety in the future. |
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