Electrochemical Sensor Constructed From Cucurbitacin/nano-gold Composite Materia

Electrochemical sensors have attracted much attention because of their advantages of simple operation,high sensitivity,good reproducibility,low cost and small size,and have broad application prospects in the determination of different biological samples.Gold nanoparticles（Au NPs）have been widely explored for their rational applications in many scientific and technological fields.Compared with conventional electrode,Au NPs modified electrode has the advantages of large effective specific surface area,enhanced mass transfer,high catalytic activity and good local environment control.In recent years,cucurbit[n]uril family has been widely used to identify amines with host and guest interactions,and some supramolecular sensors for cucurbit[n]uril with high affinity for amines have been developed.In this paper,cucurbit[6]uril and cucurbit[7]uril were used as supramolecular recognition element to prepare Q[6]/Q[7]-MOF doped gold nanocomposites,and to construct a labeling free chemical sensor with specific recognition ability.Its main contents are as follows:1)An electrochemical sensor was constructed based on Q[6]·HAu Cl₄ to detect caderamineWe prepared a relatively new metal-organic framework Q[6]·HAu Cl₄,and also used gold nanoparticles as the substrate material,which has the function of conducting and amplifying electrochemical signals to compensate for the electrical conductivity of Q[6]·HAu Cl₄ complex.To prepare the modified electrode,we used gold nanoparticles and Q[6]·HAu Cl₄ composite successively superimposed on the surface of glassy carbon electrode,and then used it as modification material to construct electrochemical sensor.The electrochemical behavior of each electrode material was characterized by CV and EIS,and the comparison showed that the composite material constructed by GCE-Au NPs-Q[6]·HAu Cl₄was beneficial to improve the sensitivity of the sensor,that is,the composite material GCE-Au NPs-Q[6]·HAu Cl₄ was successfully prepared.Under the optimal conditions,cadaver amine was quantitatively detected.When the concentration of cadaverine was detected by differential pulse voltammetry（DPV）in the range of 0.6-10μM,the linearity was good,and the detection limit was 0.03μM.The concentrations of cadaverine detected by electrochemical impedance（EIS）ranged from 0.05-1μM to 1μM-100μM,with a minimum detection limit of 0.0022μM.According to the known literature,this experiment is the first to use electrochemical impedance spectroscopy for quantitative detection of cadaver amine.2)An electrochemical sensor was constructed based on Q[7]·HAu Cl₄ to detect diphenylamineSensitive electrochemical sensing of diphenylamine（DPA）with Q[7]·HAu Cl₄was carried out.The presence of HAu Cl₄ improved the conductivity of the macrocyclic compound.To further improve the sensitivity,Au NPs were placed between the surface of GCE and Q[7]·HAu Cl₄.The electrochemical behavior of GCE-Au NPs-Q[7]·HAu Cl₄ was investigated by CV,EIS and DPV.Due to the electrochemical inertia of DPA,the unlabeled electrochemical sensor was placed in5m M K₃（Fe（CN）₆）working solution for electrochemical analysis.The sensor is linear in the DPA concentration range of 5-1000μM,the detection limit is as low as4.6μA,good reproducibility,high stability and strong anti-interference ability.The electrode was applied in tap water and apple juice to determine the recovery rate of DPA,and its practical application value was verified.