In-situ Fabrication Of Electroactive MOFs On Electrode Surface And Their Application In Electrochemical Sensors

Metal-Organic Frameworks?MOFs?have potential applications in electrochemical analysis,due to the advantages of high porosity,large surface area and adjustable pore structure.However,the traditional method of MOFs preparation and electrode modification limit the application of the MOFs.In this paper,with electrochemical method and self-assembly method,many electroactive MOFs materials were synthesized directly on a glassy carbon electrode and gold electrode,which were used as the substrate.The electrochemical sensor for the detection of dihydroxybenzene isomers and thrombin was successfully constructed with the modification electrode.The main work is expressed as follows:?1?Used the Cupric nitrate?Cu?NO₃?₂?and Trimesic acid?BTC?as raw materials,the electroactive HKUST-1 materials were synthesized on the surface of Nafion-single wall carbon nanotubes?SWCNT?modified electrode by chronoamperometry?I-t?and cyclic voltammetry?CV?method,HKUST-1/Nafion-SWCNT modified electrode was obtained.The morphology,composition and electrochemical properties of the modified electrode were characterized by scanning electron microscope?SEM?,Fourier Transform Infrared Spectrometer?FTIR?and cyclic voltammetry?CV?.The results showed that HKUST-1 was successfully synthesized.The experimental results indicated that the sensor can be used for the simultaneous detection of catechol?CT?,resorcinol?RS?and hydroquinone?HQ?,and with the oxidation peaks of CT,RS and HQ at 0.198 V,0.686 V and 0.322 V,respectively.The peak current has a good linear relationship with the concentration of Hydroquinone and its isomers in the concentration range of 0.100 M-300?M,and the detection lines were 0.390?M,0.210?M and 0.360 M respectively.The recovery rate of the actual sample was at 99.6%-101.3%,and the results were satisfactory.?2?Electroactive MOF materials of HKUST-1 and gold nanoparticle?AuNPs?were prepared on the glassy carbon electrode surface by I-t and CV electrochemical method,and the electrochemical interface based on AuNPs/HKUST-1 composites was obtained.The Au-S bond was used to immobilate the aptamer of thrombin on AuNPs/HKUST-1,and a new type of electrochemistry sensor with no tagged thrombin was constructed.The structure and electrochemical behavior of the sensor was characterized by CV,electrochemical impedance method?EIS?and differential pulse voltammetry?DPV?.When aptamers were combined with thrombin to form complexes,the microenvironment of HKUST-1/AuNPs interface was changed,and its electrochemical activity was reduced,so that it could be used for thrombin monitoring.The results showed that the peak current of the sensing interface was in good linear relationship with the thrombin concentration in the range of 1.00 fM to 1.00?M,and the detection limit was 0.41 fM based on three times signal to noise ratio?S/N?.This sensor was used to detect the thrombin in human serum sample,the recovery rate was 92.0%-102.0%.?3?A self assembled layer of thiocyanate?TCY?on the surface of a gold electrode was prepared by Au-S self-assembly chemistry.Then the TCY modified electrode was immersed in Cu?NO₃?₂ solution to obtain TCY-Cu²⁺coordination coating.Then the TCY solution was soaked in successively for 3 times,and the Cu²⁺solution was 3 times,and the(TCY-Cu²⁺)₃-TCY based electroactive MOFs modification interface was obtained.A novel thrombin electrochemical sensor was prepared by soaking the AuNPs and thrombin aptamers in order by the(TCY-Cu²⁺)₃-TCY modified electrode in order.The preparation process of the electrode was characterized by CV,EIS and DPV.The electrochemical characterization showed that the sensor showed a redox peak corresponding to the Cu²⁺/Cu⁺pair in the 0.010 M phosphoric acid buffer solution?PBS,pH 6.8?.Under the optimal conditions,the sensor could detect the thrombin in the concentration range of 1.00 fM-1.00?M,and the detection limit was 0.26 fM.The recovery rate of thrombin detection in human serum sample was 97.2%-103.0%.A novel electrochemical sensor of thrombin was prepared by soaking the AuNPs and thrombin aptamers in order by the(TCY-Cu²⁺)₃-TCY modified electrode in order.