Research And Application Of Electrochemiluminescence Sensor Based On Metal-Organic Frameworks And Its Derivatives

Electrochemiluminescence（ECL）is a special chemiluminescence phenomenon in which a light-emitting substance undergoes an oxidation or reduction on the surface of an electrode to the surface to generate light by applying an appropriate potential.ECL combines the advantages of chemiluminescence analysis and electrochemical analysis,and has wide detection range,easy controllability,rapidness and high sensitivity.It has become an imporant analytical testing menthod in recent years.The metal-organic frameworks（MOFs）is a porous material formed by metal ions and organic ligands through coordination bonds MOFs owned high specific surface area,tunable pore channels,easy functionalization and structural diversification.It have been widely used as gas separation and adsorption,photocatalysis,electrocatalysis,drug release and other fields.In this paper,the ECL sensor was constructed to detect Fe²⁺and concanavalin A（Con A）by taking advantagee of characteristics of MOFs materials and MOFs derived materials.1. A novel copper（Ⅱ）metal-organic framework（[Cu（L）（H₂O）₂]_nCu-MOF）has been successfully synthesized by facile one step hydrothermal method by CuSO₄·7H₂O and4-（3-carboxyl-1,2,4-lrl-triazol-1-yl）benzoic acid（H₂L）.Modified the glassy carbon electrode（GCE）with this kind of Cu-MOF,a strong cathode electrochemiluminescence signal was produced under the potential scan from 0.2 to-1.6 V in the potassium persulfate solution,which was about 7.7 times higher than that on the bare GCE electrode.The possible enhancement mechanism was studied in detail.The results showed that the electrochemical reduction of Cu-MOF（Cu^Ⅱ）produce Cu-MOF（Cu^I）,which can react with S₂O₈^2-to produce SO₄^·-and enhancing ECL signal intensively.In this process,Cu-MOF（Cu^I）is oxidized to Cu-MOF(Cu^Ⅱ),which realizes cyclic amplification and obtained a stable ECL signals.Based on the inhibition effect of ferrous ion on this ECL signal,a sensitive ECL method for the determination of ferrous ion.The ECL method had been applied for analysis of ferrous ion in environmental water samples successfully.2. ZIF-67 is calcined in an inert gas environment to obtained nitrogen-doped carbon nanotubes frameworks material（NCNTFs）.This material has a high surface area and can be used as substrate materials to load more horse radish peroxidase（HRP）.Using nitrogen-doped graphene quantum dots（NGQDs）as reducing agents,Ag NO₃was reduced to Ag NPs to obtain the NGQDs@Ag NPs.NGQDs@Ag NPs was used as a luminescence signal and load more glucose oxidas（GOx）.Based on the specific recognition between sugar and lection,a sandwich Con A sensor was established.In this sensor,luminescence signal of NGQDs@Ag NPs is directly related to the content of Con A.The higher the content of Con A,the more signal probe NGQDs@Ag NPs bound to the electrode and ECL signal will also increase.Based on the enhancement of the luminescence of NGQDs by Ag NPs and large surface area of NCNTFs.The detection of Con A of ECL sensor was achieved with a linear range from 0.05 ng/mL to 10 ng/mL with a detection limit of 0.02ng/mL（S/N=3）.3. Using 4-（1,2,4-triazol-1-yl）isophthalic acid and Zn（NO₃）₂.6H₂O as raw materials,a novelthree-dimensionalporousmetalorganicframework（{[Zn₅（μ₃-OH）₂（BDPP）₂（H₂O）₂]·（DMA）₃（H₂O）₄}_n,Zn-MOF）was synthesized.An ultrasensitive sandwich electrochemiluminescence biosensor was designed for determination of Con A through specific carbohydrate–Con A interaction.Zn-MOF loaded a large amount of luminescent reagents as luminol by encapsulating into its pores to obtained Zn-MOF@luminol complex.Zn-MOF can enhance ECL signal of luminol.In order to further enhance luminescence of Zn-MOF@luminol complex,a three-dimensional hierarchical molybdenum disulfide nanoflower and multiwalled carbon nanotubes complex（Mo S₂NF@MWCNTs）was used as a substrate to modify the glassy carbon electrode.The large specific surface of Zn-MOF and Mo S₂NF@MWCNTs were used to immobilize a large amount of HRP and GOx on their surfaces.In this way,a sandwich ECL sensor for measuring Con A.In experiment,Zn-MOF not noly immobilize a large amount of luminol,but also can be acted as the coreactant accelerator to promote the decomposition of H₂O₂into active oxygen and enhance ECL signal.Combined HRP and peroxidase-mimicking enzyme property of Mo S₂NF@MWCNTs on luminol-H₂O₂ECL signal realized the amplification of the triple signal.Meanwhile,Zn-MOF also acted as the coreactant accelerator during the luminol ECL.This Zn-MOF@luminol complex with strong ECL performance was used as the signal probe to achieve super strong ECL signal.Under the optimal experimental conditions,the ECL sensor exhibited a wide linear response ranging from 0.5 pg/ml to 100 ng/mL and a low detection limit of 0.3 pg/mL（S/N=3）for the determination of ConA.