Construction Of Graphene-pillarene Supramolecular Composite Membrane And Its Application In Electrochemical Sensors

As a two-dimensional carbon material,graphene shows great potential in electrochemical sensors due to its good electrochemical stability,large specific surface area and high conductivity.On the other hand,molecular recognition in supramolecular chemistry is characterized by a high degree of selectivity and reversibility,which coincides with the requirements of sensors for sensitive membranes.Pillararene,as one of the important supermolecules,have shown some unique characteristics in the recognition process of guest molecules,which provide the possibility for their development in electrochemical sensing.In this paper,pillararene immobilizing onto graphene to obtain pillararene functionalized graphene composites with molecular recognition ability.As a modified material,a new electrochemical sensor was constructed on the electrode surface.The specific research content is as follows:（1）Water-soluble amino-functionalized pillar[6]arene（CP6）was modified onto the surface of graphene oxide（GO）,through Fourier transform infrared spectrum（FTIR）,ultraviolet-visible spectrum（UV-Vis）,thermo gravimetric analysis（TGA）,X-ray photoelectron spectroscopy（XPS）and Zeta potential were used to characterize the performance of GO-CP6.Using the pulse potential method（PPM）,GO reduction and electrode modification were realized in one step,and electrochemical reduction grapheme-amino-functionalized pillar[6]arene（Er GO-CP6）modified glassy carbon electrode（GCE）was constructed.Scanning electron microscopy（SEM）,Raman spectroscopy（Raman）and cyclic voltammetry（CV）were used to characterize the Er GO-CP6 modified electrode（Er GO-CP6/GCE）.On this basis,the electrochemical response and molecular recognition ability of theophylline（TP）,ascorbic acid（AA）,acetaminophen（APAP）and folic acid（FA）guest molecules at the modified electrode were studied.The experimental results show that,compared with GCE and Er GO/GCE,Er GO-CP6/GCE exhibits a better electrochemical response to the guest molecules.The results shows that Er GO-CP6 film not only has excellent electrical properties of graphene,but also exhibits CP6 supermolecular recognition and enrichment capabilities,thereby improving the electrochemical response of molecules.¹H NMR and 2D NOESY experiments confirmed that guest molecules such as TP can enter the cavity of CP6 and form a host-guest complex with interpenetrating structure.（2）Compare of two supramolecularβ-cyclodextrin（β-CD）and carboxylated-pillar[6]arene（WP6）for recognition of 8-azaguanine（8-AG）.Though fluorescence analysis to obtain binding stoichiometry is 1:1,and WP6 has strong binding constant thanβ-CD for 8-AG.The modified electrode of Er GO-β-CD/GCE and Er GO-WP6/GCE was prepared by Cyclic voltammetry to analyze and detect8-AG.[Fe（CN）6]^3-/^4-was used as an electrochemical probe to prove Er GO-WP6/GCE has more excellent electrocatalytic activity and conductivity.Under the optimal experimental conditions,the experimental results showed that the detection limit of Er GO-WP6/GCE for 8-AG was 8.0 n M.The method has been applied to the detection of 8-AG in urine samples with satisfactory results.（3）The complexation between the CP6,β-CD and Imidacloprid（IDP）in water was studied by ¹H NMR.IDP was selected as the guest molecule,which showed a binding constant（1.05±0.04）×10⁴ M^-1 with 1:1 binding stoichiometry.On this basis,The Er GO-CP6/GCE electrochemical sensor was constructed by PPM,and the electrochemical behavior of IDP on the Er GO-CP6 modified electrode was studied.The relevant kinetic parameters were calculated and the redox reaction mechanism was proposed.Under the optimal experimental conditions,Under optimal conditions,there is a linear relationship between the current response of IDP and the concentration in the range of 0.1～40?M,and the detection limit is 0.01?M（S/N=3）.