Research And Application Of Electrochemical Immunosensor Based On Copper Composite Materials

The electrochemical immunosensor based on the specific recognition between antigen and antibody plays an important role in the detection and analysis of disease markers with its advantages of high sensitivity,low detection limit,high selectivity,low cost,simple and fast.With the rapid development of material science,the sensitivity and stability of electrochemical immunosensor have been further developed.In this paper,a series of electrochemical immunosensors have been constructed for the sensitive detection of target analytes based on copper matrix composite materials and various sensing strategies.This paper mainly includes four parts.（1）A ratiometric electrochemical immunosensor for quantitative analysis of neuron specific enolase（NSE）was constructed.Cu-MOFs-Au was used as the base material,and Fc-L-Cys was used as the label material of Ab₂.The two materials introduce strong and stable DPV dual signals to the sensor,which provides the basis for the realization of signal ratio.It is noteworthy that with the increase of NSE concentration,the response signal of Cu-MOFs-Au gradually decreases,and the response signal of Fc-L-Cys gradually increases.In order to improve the sensitivity of target molecular analysis,the sensing strategy uses the ratio of two different signals(ΔI=ΔI_Cu/ΔI_Fc)and NSE concentration to draw the working curve.Under the optimal experimental conditions,the electrochemical immunosensor shows good analytical and detection performance within the concentration range of 1 pg/mL-1μg/mL,and the detection limit is 0.011 pg/mL.（2）Cu₂SnS₃-Au was used as electrode sensing platform,β-FeOOH-Pd was used as a secondary antibody marker to construct a dual-mode sandwich electrochemical immunosensor with signal amplification for the detection of carcinoembryonic antigen（CEA）.On the one hand,Cu₂SnS₃-Au can provide a DPV signal for electrochemical immunosensor and has the remarkable characteristics of catalyzing H₂O₂,β-FeOOH-Pd also shows an effective catalytic effect on H₂O₂,which greatly promotes the amplitude of electrochemical response signal change,so the purpose of sensor signal amplification is realized.On the other hand,the electrochemical immunosensor outputs two different electrochemical response signals through two detection methods,and the two modes verify each other,reducing the system error and improving the detection accuracy of the sensor system.Under the optimal experimental conditions,the electrochemical immunosensor shows good analytical and detection performance within the concentration range of 100 fg/mL-50 ng/mL,and the detection limit are19.95 fg/mL（DPV）and 33.25 fg/mL（i-t）.（3）With CuCo₂O₄-Au as the base,ZIF-8@SiO₂ as an electronic obstruction tag,a competitive electrochemical immunosensor based on DPV and i-t dual response mode was constructed for the detection of aflatoxin B1（AFB1）.CuCo₂O₄-Au can output DPV signal in PBS liquid environment,and has the characteristic of catalytic H₂O₂,which can provide dual-source response signals for electrochemical immunosensor.ZIF-8@SiO₂ has poor conductivity and has a significant effect on blocking electron transfer,ZIF-8@SiO₂-BSA-AFB1 competes with AFB1 for a limited antibody binding site,but with the gradual increase of AFB1 concentration,the hindrance of electron transfer decreases,and the electrochemical signal strength increases gradually.Under the optimal experimental conditions,the electrochemical immunosensor shows good analytical and detection performance within the concentration range of 1 pg/mL-500 ng/mL,and the detection limit are 0.23 pg/mL（DPV）and0.37 pg/mL（i-t）.（4）Combined with SWV,a novel label-free electrochemical immunosensor was constructed.Wherein Fe₃O₄@MnO₂@Cu（Im）₂@Au NPs is used as electrode modification material to improve the electrode performance.Fe₃O₄@MnO₂@Cu（Im）₂ has a large specific surface area,which can provide more locations for the loading of gold nanoparticles,which can make the combination of antibody and antigen stronger,and also increase the loading concentration of antibody,so it can make the electrochemical immunosensor more stable.At the same time,the electron transfer ability of the substrate material is also very superior,which ensures the sensitivity of the sensor during the test process.Under the optimal experimental conditions,the electrochemical immunosensor is used to detect diethylstilbestrol（DES）,and the detection concentration range is 10 pg/mL-1μg/mL,the detection limit is 3.31 pg/mL.