Electrode modification material, preparation method and application thereof

Abstract

The application relates to the technical field of chemically modified electrodes, and discloses an electrode modification material, a preparation method and application thereof. The electrode modification material comprises graphene oxide doped polyacrylonitrile-based carbon nanofibers and UIO-66-NH2; the UIO-66-NH2 is loaded on the surface of the graphene oxide doped polyacrylonitrile-based carbon nanofibers. The electrode modification material provided by the application is graphene oxide doped polyacrylonitrile-based carbon nanofibers uniformly dispersed with UIO-66-NH2 on the surface. The UIO-66-NH2 is stable in water, has a large specific surface area and high porosity, the graphene oxide improves the strength, hardness and conductivity of the carbon nanofibers, the conductivity and electrochemical activity are improved after the UIO-66-NH2 is combined with the graphene oxide doped polyacrylonitrile-based carbon nanofibers, the obtained electrode modification material has a large specific surface area, many active sites and high electrocatalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of chemically modified electrodes, and in particular to an electrode modification material, a preparation method and an application thereof. Background Art

[0002] Lincomycin (LIN) is a natural antibacterial drug from the lincosamide class synthesized by Streptomyces. It can treat diseases caused by aerobic and anaerobic Gram-positive bacteria and is widely used in the livestock and food production industries. However, excessive use of lincomycin not only leads to bacterial resistance, reduces the drug's effectiveness or renders it ineffective, but also causes environmental pollution and threatens human health.

[0003] There are many methods for detecting lincomycin, including surface-enhanced Raman spectroscopy (SERS), liquid chromatography-tandem mass spectrometry (LC-MS / MS), accelerated solvent-solid phase extraction-gas chromatography-mass spectrometry (ASE / SPE-GC / MS), high-performance liquid chromatography, and high-performance liquid chromatography-mass spectrometry / tandem mass spectrometry (HPLC–MS / MS-TOF). However, these methods generally suffer from drawbacks such as expensive equipment and complex sample pretreatment, which limits their practical application. Electrochemiluminescence (ECL) offers advantages such as simplicity, low cost, and rapid analysis, and has the potential to be used for the rapid detection of lincomycin. However, it suffers from low sensitivity. Summary of the Invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one object of the present invention is to provide an electrode modification material; a second object of the present invention is to provide a method for preparing such an electrode modification material; a third object of the present invention is to provide a chemically modified electrode; a fourth object of the present invention is to provide an electrochemiluminescence sensor; and a fifth object of the present invention is to provide applications of such a chemically modified electrode or electrochemiluminescence sensor.

[0005] The basic principles of the present invention are described as follows:

[0006] 1) Metal-organic framework materials (MOFs) have the advantages of large specific surface area, high porosity, and surface modification, and are often used as electrode modification materials. However, MOFs generally have the problem of poor stability in aqueous solution. The Zr-based metal-organic framework UIO-66-NH2 containing amino functional groups forms a strong coordination bond between the metal node (Zr) and the organic linker (uracil), which can limit the coordinated water molecules of the Zr node, thereby enhancing the stability of the framework and reducing the dissolution of the framework in water. In addition, the amino group can form hydrogen bonds with water molecules, enhancing the dispersibility of the framework in water. Therefore, the present invention selects the metal-organic framework UIO-66-NH2 with good stability in aqueous solution as the basis of the electrode modification material;

[0007] 2) UIO-66-NH2 has low inherent conductivity, so the present invention improves its conductivity and electrochemical activity by combining it with highly conductive materials. Among various highly conductive materials, carbon nanofiber materials (CNFs) have the advantages of good conductivity, corrosion resistance, high temperature resistance, small weight and low cost;

[0008] 3) The performance of carbon nanofiber materials is closely related to the physical and structural properties of their precursor fibers. Polyacrylonitrile (PAN) is a high molecular weight polymer. Polyacrylonitrile-based carbon nanofibers prepared with polyacrylonitrile as a precursor have the characteristics of high specific surface area and high stability.

[0009] 4) Filling the precursor fibers with nanoparticles can improve the strength, hardness, and conductivity of carbon nanofibers. Graphene oxide (GO) has higher amphiphilicity and reactivity than other nanomaterials, and also has advantages such as a large specific surface area, good dispersibility, and multiple functional groups. Therefore, the present invention selects polyacrylonitrile filled with graphene oxide as a precursor to prepare carbon nanofiber materials, and combines the carbon nanofiber materials with UIO-66-NH2 to obtain an electrode modified material with high conductivity and electrochemical activity.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A first aspect of the present invention provides an electrode modification material, which includes graphene oxide-doped polyacrylonitrile-based carbon nanofibers and UIO-66-NH2; the UIO-66-NH2 is loaded on the surface of the graphene oxide-doped polyacrylonitrile-based carbon nanofibers.

[0012] In some embodiments of the present invention, the electrode modification material includes the following preparation raw materials: polyacrylonitrile, graphene oxide, a zirconium source, an organic ligand, and a solvent.

[0013] In some embodiments of the present invention, the mass ratio of graphene oxide to polyacrylonitrile is 1:(10-15).

[0014] In the present invention, polyacrylonitrile is used as a precursor for preparing carbon nanofibers, and graphene oxide with high amphiphilicity and reactivity, large specific surface area, good dispersibility and many functional groups is used as filling nanoparticles, which can improve the strength, hardness and conductivity of polyacrylonitrile-based carbon nanofibers.

[0015] In some embodiments of the present invention, the zirconium source is selected from at least one of zirconium chloride, zirconium acetate, and zirconium sulfate.

[0016] In some specific embodiments of the present invention, the zirconium source is zirconium chloride (ZrCl 4 ).

[0017] In some embodiments of the present invention, the organic ligand is selected from at least one of terephthalic acid, 2-aminoterephthalic acid, 2-methylterephthalic acid, 2-bromoterephthalic acid, 2-nitroterephthalic acid, and 2,4-dichloroterephthalic acid.

[0018] In some specific embodiments of the present invention, the organic ligand is 2-aminoterephthalic acid.

[0019] In some specific embodiments of the present invention, the mass ratio of the zirconium source to the organic ligand is 1:(1-1.3).

[0020] In some embodiments of the present invention, the solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP).

[0021] In some specific embodiments of the present invention, the solvent is N,N-dimethylformamide.

[0022] The second aspect of the present invention provides a method for preparing the electrode modifying material according to the first aspect of the present invention, comprising the following steps:

[0023] S1, mixing polyacrylonitrile, graphene oxide and a solvent to form a precursor solution, and electrospinning to obtain graphene oxide-doped polyacrylonitrile fibers;

[0024] S2. carbonizing the graphene oxide-doped polyacrylonitrile fibers to obtain graphene oxide-doped polyacrylonitrile-based carbon nanofibers;

[0025] S3. Mixing a zirconium source, an organic ligand and a solvent, adding graphene oxide-doped polyacrylonitrile-based carbon nanofibers to form a suspension, heating and reacting to obtain the electrode modification material.

[0026] In some embodiments of the present invention, in step S1, the ratio of graphene oxide, polyacrylonitrile and solvent is 1 g: (10-15) g: (25-35) mL.

[0027] In some specific embodiments of the present invention, in step S1, the ratio of graphene oxide, polyacrylonitrile and solvent is 1 g: (10-12) g: (25-30) mL.

[0028] In some embodiments of the present invention, in step S1, the graphene oxide, polyacrylonitrile and solvent are mixed and stirred at 20-25° C. for 10-15 hours to form a precursor solution.

[0029] In some embodiments of the present invention, in step S1, the electrospinning process parameters include at least one of the following parameters:

[0030] 1) The needle distance is 15-20cm;

[0031] 2) The speed of the wire drum is 160-220r / min;

[0032] 3) Voltage is 11-15kV;

[0033] 4) The injection rate is 1-2 mL / h.

[0034] In some specific embodiments of the present invention, in step S1, the electrospinning process parameters include at least one of the following parameters:

[0035] 1) The needle distance is 15-18cm;

[0036] 2) The speed of the wire drum is 160-180r / min;

[0037] 3) Voltage is 11-13kV;

[0038] 4) The injection rate is 1-1.5 mL / h.

[0039] In the present invention, polyacrylonitrile is used as a precursor to prepare polyacrylonitrile-based carbon nanofibers through an electrostatic spinning method, which can make the carbon nanofibers have a high specific surface area and high stability.

[0040] In some embodiments of the present invention, in step S2, the carbonization includes first heating the temperature to 200-250°C at a rate of 5-10°C / min, keeping it warm for 2-3 hours for pre-oxidation, and then heating the temperature to 600-800°C at a rate of 5-10°C / min under a protective atmosphere, and keeping it warm for 3-5 hours.

[0041] In some specific embodiments of the present invention, in step S2, the carbonization includes first heating the temperature to 230-250°C at a rate of 5-7°C / min, keeping the temperature for 2-2.5 hours for pre-oxidation, and then heating the temperature to 600-700°C at a rate of 5-7°C / min under a protective atmosphere, and keeping the temperature for 3-4 hours.

[0042] In some embodiments of the present invention, in step S2, the protective atmosphere includes nitrogen.

[0043] In the present invention, graphene oxide-doped polyacrylonitrile fibers are first placed in a muffle furnace for pre-oxidation, and then transferred to a tubular furnace for high-temperature carbonization under a protective atmosphere. This can ensure that the graphene oxide-doped polyacrylonitrile fibers are completely carbonized, thereby obtaining graphene oxide-doped polyacrylonitrile-based carbon nanofibers with excellent performance.

[0044] In some embodiments of the present invention, in step S3, the ratio of the zirconium source, the organic ligand, and the solvent is 1 g: (1-1.3) g: (60-120) mL.

[0045] In some specific embodiments of the present invention, in step S3, the ratio of the zirconium source, the organic ligand, and the solvent is 1 g: (1-1.1) g: (60-100) mL.

[0046] In some embodiments of the present invention, in step S3, the mass ratio of the zirconium source to the graphene oxide-doped polyacrylonitrile-based carbon nanofibers is 1:(0.1-1.5).

[0047] In some specific embodiments of the present invention, in step S3, the mass ratio of the zirconium source to the graphene oxide-doped polyacrylonitrile-based carbon nanofibers is 1:(0.1-1.3).

[0048] In some embodiments of the present invention, in step S3, the zirconium source, organic ligand and solvent are mixed and then stirred at 20-25° C. for 25-35 minutes.

[0049] In some embodiments of the present invention, in step S3, after adding the graphene oxide-doped polyacrylonitrile-based carbon nanofibers, stirring is carried out at 20-25° C. for 25-35 minutes to obtain a suspension.

[0050] In some embodiments of the present invention, in step S3, the heating reaction temperature is 100-120° C. and the time is 12-18 hours.

[0051] In some specific embodiments of the present invention, in step S3, the heating reaction temperature is 110-120° C. and the time is 12-15 hours.

[0052] In the present invention, a zirconium source, an organic ligand and a solvent are first mixed and reacted to form UIO-66-NH2, and then the UIO-66-NH2 is uniformly loaded on the surface of graphene oxide-doped polyacrylonitrile-based carbon nanofibers through a solvent method to form a uniformly dispersed electrode modification material, thereby avoiding the problem of large-scale agglomeration of UIO-66-NH2 and improving the electrocatalytic activity of the electrode modification material.

[0053] In some embodiments of the present invention, in step S3, after the heating reaction is completed, washing and drying steps are also included.

[0054] In some embodiments of the present invention, the washing reagent includes methanol, N,N-dimethylformamide and ethanol.

[0055] In some embodiments of the present application, the drying temperature is 50-70℃.

[0056] In some embodiments of the present application, the drying time is 8-12h.

[0057] The third aspect of the present application provides a chemically modified electrode, wherein the chemically modified electrode is loaded with the electrode modification material according to the first aspect of the present application.

[0058] In some embodiments of the present application, the chemically modified electrode is prepared by a method comprising the following steps: polishing, washing and drying the electrode to be modified, grinding the electrode modification material and adding it to a dispersion, ultrasonic dispersion to form a suspension, adding the suspension dropwise to the electrode to be modified, and drying to obtain the chemically modified electrode.

[0059] In some embodiments of the present application, the dispersion is a mixture of ultrapure water, isopropanol and perfluorinated resin solution (5wt% Nafion solution) in a volume ratio of (15-17):(3-5):1.

[0060] In some embodiments of the present application, the concentration of the electrode modification material in the suspension is (1-1.5)mg / mL.

[0061] In some embodiments of the present application, the amount of the electrode modification material is 5-10μg per electrode to be modified.

[0062] In some embodiments of the present application, the electrode to be modified comprises a glassy carbon electrode (GCE).

[0063] In some embodiments of the present application, the washing reagent for the electrode to be modified comprises water and ethanol.

[0064] The fourth aspect of the present application provides an electrochemiluminescence sensor comprising the chemically modified electrode according to the third aspect of the present application.

[0065] In some embodiments of the present application, the electrochemiluminescence sensor comprises an Ag / AgCl electrode as a reference electrode, a Pt electrode as a counter electrode, and the chemically modified electrode as a working electrode.

[0066] The fifth aspect of the present application provides the use of the chemically modified electrode according to the third aspect of the present application, or the electrochemiluminescence sensor according to the fourth aspect of the present application in the detection of lincomycin.

[0067] In some embodiments of the present application, the use comprises the detection of lincomycin (LIN) in milk.

[0068] Compared with the prior art, the present application has the following advantages:

[0069] 1) The electrode modification material provided by the application is graphene oxide doped polyacrylonitrile-based carbon nanofiber uniformly dispersed with UIO-66-NH2 on the surface, UIO-66-NH2 has good stability in water, large specific surface area and high porosity, and the graphene oxide improves the strength, hardness and conductivity of the carbon nanofiber, after the combination of UIO-66-NH2 and the graphene oxide doped polyacrylonitrile-based carbon nanofiber, the conductivity and electrochemical activity are improved, and the obtained electrode modification material has a reticular structure of mutual crosslinking, large specific surface area, many active sites and high electrocatalytic activity;

[0070] 2) The preparation method of the electrode modification material provided by the application is simple, polyacrylonitrile-based carbon nanofiber is prepared by electrospinning, so that the carbon nanofiber has high specific surface area and high stability, and UIO-66-NH2 is loaded on the surface of the carbon nanofiber by a solvent method, so that the agglomeration of UIO-66-NH2 can be avoided, and the electrocatalytic activity of the electrode modification material is ensured;

[0071] 3) The electrochemical modification electrode provided by the application can be used as a working electrode of an electrochemiluminescence sensor after being modified by the electrode modification material, and has high detection sensitivity;

[0072] 4) The electrochemiluminescence sensor containing the electrochemical modification electrode provided by the application can be applied to the detection of lincomycin, has high detection sensitivity, fast detection speed, low equipment cost and reliable detection results. BRIEF DESCRIPTION OF DRAWINGS

[0073] Figure 1 SEM images of PAN / CNFs, GO, GO / PAN / CNFs and UIO-66-NH2 / GO / PAN / CNFs;

[0074] Figure 2 TEM image of the electrode modification material in Example 1;

[0075] Figure 3 EDS distribution maps of C (a), O (b), N (c) and Zr (d) elements of the electrode modification material in Example 1;

[0076] Figure 4 XRD diffraction patterns of UIO-66-NH2, GO / PAN / CNFs and UIO-66-NH2 / GO / PAN / CNFs;

[0077] Figure 5 XPS pattern of the electrode modification material in Example 1;

[0078] Figure 6 C1s characteristic peak spectrum of the electrode modification material in Example 1;

[0079] Figure 7 This is the N1s characteristic peak spectrum of the electrode modification material in Example 1;

[0080] Figure 8 This is the O1s characteristic peak spectrum of the electrode modification material in Example 1;

[0081] Figure 9 This is the Zr3d characteristic peak spectrum of the electrode modification material in Example 1;

[0082] Figure 10 For Ru(bpy)3 in Application Example 5 2+ -CV curves of LIN system on different working electrodes;

[0083] Figure 11 For Ru(bpy)3 in Application Example 5 2+ -LIN system ECL curves at different working electrodes. DETAILED DESCRIPTION

[0084] The present invention is further described in detail below using specific examples. Unless otherwise specified, the raw materials, reagents, and apparatus used in the examples and comparative examples are available from conventional commercial sources or by conventional methods. Unless otherwise specified, all experimental or testing methods are conventional in the art.

[0085] The molecular weight of polyacrylonitrile used in the following examples and comparative examples is Mw = 150,000 g / mol; N,N-dimethylformamide is analytical grade and purchased from Guangdong Guanghua Technology Co., Ltd.; graphene oxide is purchased from Shenzhen Suiheng Technology Co., Ltd.; Nafion solution (5 wt%) is purchased from Shanghai Hesen Electric Co., Ltd.; the concentration of phosphate buffer (PBS) is 0.1 mol / L, and Na2HPO4 and NaH2PO4 are used as raw materials, and H3PO4 and KOH are used to adjust the pH.

[0086] Example 1

[0087] This embodiment prepares an electrode modification material in the following steps:

[0088] S11. Add 1 g of graphene oxide and 10 g of polyacrylonitrile to 27 mL of N,N-dimethylformamide and stir at room temperature for 12 h to obtain an electrospinning precursor solution; transfer the precursor solution to a syringe with a roller distance (needle pitch) of 16.6 cm and a roller speed (receiving drum speed) of 160 rpm attached to aluminum foil. Electrospinning is performed at an injection rate of 1.5 mL / h under a high voltage of 11.03 kV to obtain graphene oxide-doped polyacrylonitrile fibers;

[0089] S12, placing the graphene oxide-doped polyacrylonitrile fiber in a muffle furnace, heating it to 250°C at a rate of 5°C / min, and keeping it warm for 2 hours for pre-oxidation, then transferring the material to a tube furnace, heating it to 600°C at a rate of 5°C / min under a N2 atmosphere, and keeping it warm at this temperature for 3 hours to ensure that the material is carbonized, and then cooling it to room temperature to obtain graphene oxide-doped polyacrylonitrile-based carbon nanofibers;

[0090] S13. Dissolve 0.83 g ZrCl4 and 0.89 g 2-aminoterephthalic acid in 50 mL N,N-dimethylformamide, stir at room temperature for 30 min to mix evenly, then add 0.5 g graphene oxide-doped polyacrylonitrile-based carbon nanofibers, continue stirring for 30 min to obtain a uniformly dispersed suspension, transfer the suspension to a Teflon-lined autoclave and heat at 120 ° C for 12 h, then collect the product at room temperature, wash it thoroughly with methanol, N,N-dimethylformamide and ethanol, and dry it under vacuum at 60 ° C overnight to obtain the electrode modified material (UIO-66-NH2 / GO / PAN / CNFs).

[0091] Comparative Example 1

[0092] This comparative example prepares a polyacrylonitrile-based carbon nanofiber in the following steps:

[0093] 10 g of polyacrylonitrile was added to 27 mL of N,N-dimethylformamide and stirred at room temperature for 12 h to obtain an electrospinning precursor solution. The precursor solution was transferred to a syringe with a roller distance (needle pitch) of 16.6 cm and a roller speed (receiving drum speed) of 160 rpm. Electrospinning was performed at a high voltage of 11.03 kV and an injection rate of 1.5 mL / h to obtain polyacrylonitrile fibers.

[0094] 2) Place the polyacrylonitrile fiber in a muffle furnace, heat it to 250°C at a rate of 5°C / min, and keep it for 2 hours for pre-oxidation. Then transfer the material to a tube furnace, heat it to 600°C at a rate of 5°C / min under N2 atmosphere, and keep it at this temperature for 3 hours to ensure that the carbonization of the material is complete. Cool it to room temperature to obtain polyacrylonitrile-based carbon nanofibers (PAN / CNFs).

[0095] Comparative Example 2

[0096] In this comparative example, a graphene oxide-doped polyacrylonitrile-based carbon nanofiber is prepared in the following steps:

[0097] 1) 1 g of graphene oxide and 10 g of polyacrylonitrile were added to 27 mL of N,N-dimethylformamide and stirred at room temperature for 12 h to obtain an electrospinning precursor solution. The precursor solution was transferred to a syringe with a roller distance (needle pitch) of 16.6 cm and a roller speed (receiving drum speed) of 160 rpm attached to aluminum foil. Electrospinning was performed at an injection rate of 1.5 mL / h under a high voltage of 11.03 kV to obtain graphene oxide-doped polyacrylonitrile fibers.

[0098] 2) The graphene oxide-doped polyacrylonitrile fiber was placed in a muffle furnace, heated to 250°C at a rate of 5°C / min, and kept warm for 2 hours for pre-oxidation. The material was then transferred to a tube furnace, heated to 600°C at a rate of 5°C / min under a N2 atmosphere, and kept warm at this temperature for 3 hours to ensure that the material was carbonized. The carbonization was completed and the material was cooled to room temperature to obtain graphene oxide-doped polyacrylonitrile-based carbon nanofibers (GO / PAN / CNFs).

[0099] Comparative Example 3

[0100] This comparative example prepares a UIO-66-NH2 in the following steps:

[0101] 1) Dissolve 0.83 g ZrCl4 and 0.89 g 2-aminoterephthalic acid in 50 mL N,N-dimethylformamide and stir at room temperature for 30 min to mix thoroughly to obtain a homogeneous solution;

[0102] 2) The homogeneous solution was placed in a Teflon-lined autoclave and heated at 120°C for 12 h. After the reaction, the mixture was naturally cooled to room temperature. The powder was collected by filtration, washed thoroughly with methanol, N,N-dimethylformamide, and ethanol, and dried under vacuum at 60°C overnight to obtain UIO-66-NH2.

[0103] Application Example 1

[0104] This application example provides a chemically modified electrode. The steps are as follows:

[0105] 1) Polish the glassy carbon electrode on chamois leather with 0.5 μm alumina powder, clean the electrode with ultrapure water and ethanol, and blow dry with nitrogen.

[0106] 2) The electrode modification material UIO-66-NH2 / GO / PAN / CNFs prepared in Example 1 was ground into powder, 1 mg of the powder was added to 1 mL of a dispersion solution (ultrapure water:isopropanol:Nafion solution = 16:4:1, v / v / v), and ultrasonically dispersed for 30 min to obtain a UIO-66-NH2 / GO / PAN / CNFs suspension;

[0107] 3) Use a pipette to transfer 5 μL of the UIO-66-NH2 / GO / PAN / CNFs suspension to modify the glassy carbon electrode, and place it at room temperature to dry to obtain a chemically modified electrode (UIO-66-NH2 / GO / PAN / CNFs / GCE).

[0108] Application Example 2

[0109] This application example provides a chemically modified electrode. The steps are as follows:

[0110] 1) Polish the glassy carbon electrode on chamois leather with 0.5 μm alumina powder, clean the electrode with ultrapure water and ethanol, and blow dry with nitrogen.

[0111] 2) The polyacrylonitrile-based carbon nanofibers PAN / CNFs prepared in Comparative Example 1 were ground into powder, 1 mg of the powder was added to 1 mL of a dispersion solution (ultrapure water:isopropanol:Nafion solution = 16:4:1, v / v / v), and ultrasonically dispersed for 30 min to obtain a PAN / CNFs suspension;

[0112] 3) Use a pipette to transfer 5 μL of PAN / CNFs suspension to modify the glassy carbon electrode and place it at room temperature to dry to obtain a chemically modified electrode (PAN / CNFs / GCE).

[0113] Application Example 3

[0114] This application example provides a chemically modified electrode. The steps are as follows:

[0115] 1) Polish the glassy carbon electrode on chamois leather with 0.5 μm alumina powder, clean the electrode with ultrapure water and ethanol, and blow dry with nitrogen.

[0116] 2) The graphene oxide-doped polyacrylonitrile-based carbon nanofibers (GO / PAN / CNFs) prepared in Comparative Example 2 were ground into powder, 1 mg of the powder was added to 1 mL of a dispersion solution (ultrapure water:isopropanol:Nafion solution = 16:4:1, v / v / v), and ultrasonically dispersed for 30 min to obtain a GO / PAN / CNFs suspension;

[0117] 3) Use a pipette to transfer 5 μL of GO / PAN / CNFs suspension to modify the glassy carbon electrode and place it at room temperature to dry to obtain a chemically modified electrode (GO / PAN / CNFs / GCE).

[0118] Application Example 4

[0119] This application example provides a chemically modified electrode. The steps are as follows:

[0120] 1) Polish the glassy carbon electrode on chamois leather with 0.5 μm alumina powder, clean the electrode with ultrapure water and ethanol, and blow dry with nitrogen.

[0121] 2) Grind the UIO-66-NH2 prepared in Comparative Example 3 into a powder, take 1 mg of the powder and add it to 1 mL of a dispersion solution (ultrapure water:isopropanol:Nafion solution = 16:4:1, v / v / v), and ultrasonically disperse it for 30 minutes to obtain a UIO-66-NH2 suspension;

[0122] 3) Use a pipette to transfer 5 μL of the UIO-66-NH2 suspension to modify the glassy carbon electrode, and place it at room temperature to dry to obtain a chemically modified electrode (UIO-66-NH2 / GCE).

[0123] Application Example 5

[0124] This application example uses an MPI-E electrochemiluminescence analyzer (Xi'an Ruimai Analytical Instrument Co., Ltd.) to detect lincomycin in milk. A Pt electrode is used as the counter electrode, an Ag / AgCl electrode is used as the reference electrode, and the chemically modified electrodes prepared in Application Examples 1-4 are used as working electrodes:

[0125] Three different brands of milk were purchased from a supermarket. 1.5 mL of each was centrifuged at 10,000 rpm at 4°C. The supernatant was collected and filtered through a sterile microporous membrane (0.22 μm). 1 mL of the milk sample was added to 10 mL of PBS buffer (pH 7.0) for later use.

[0126] Dissolve tris(2,2-bipyridyl)ruthenium(II) chloride hexahydrate in water and prepare 1×10 -4 mol / LRu(bpy)3 2+ Then take 100μm 1×10 -4 mol / LRu(bpy)3 2+ solution, 100 μ m 0.1 mol / L phosphate buffer, constitutes the electrolyte solution;

[0127] The MPI-E electrochemiluminescence analyzer parameters were set as follows: cyclic voltammetry potential range 0.2-1.25 V, scan rate 0.1 V / s, scan segment 2, sampling interval 0.001 V, standing time 4 s, MPI-E instrument detection time 18 s, sampling rate 10 T / s. Under the above parameters, different working electrodes were placed in the electrolyte solution for lincomycin electrochemiluminescence detection, cyclic voltammetry was used for scanning, and the ECL signal was recorded.

[0128] Material characterization and performance testing

[0129] 1. Graphene oxide GO, polyacrylonitrile-based carbon nanofibers PAN / CNFs in Comparative Example 1, graphene oxide-doped polyacrylonitrile-based carbon nanofibers GO / PAN / CNFs in Comparative Example 2, and the electrode modification material UIO-66-NH2 / GO / PAN / CNFs in Example 1 were characterized using an SU8220 ultra-high resolution cold field emission scanning electron microscope (SEM, JEOL Ltd.):

[0130] Figure 1 SEM images of PAN / CNFs, GO, GO / PAN / CNFs and UIO-66-NH2 / GO / PAN / CNFs, among which, Figure 1 (a) is the SEM image of polyacrylonitrile-based carbon nanofibers PAN / CNFs in Comparative Example 1, Figure 1 (b) is the SEM image of graphene oxide GO. Figure 1 (c) is the SEM image of graphene oxide-doped polyacrylonitrile-based carbon nanofibers GO / PAN / CNFs in Comparative Example 2, Figure 1 (d) and Figure 1 (e) is the SEM image of the electrode modification material UIO-66-NH2 / GO / PAN / CNFs in Example 1. Figure 1 (a) It can be seen that polyacrylonitrile-based carbon nanofibers are continuous and uniform two-dimensional fibrous structures; Figure 1 (b) It can be seen that graphene oxide has a sheet structure and is accompanied by surface wrinkles; Figure 1 (c) It can be seen that after adding graphene oxide, the structure of polyacrylonitrile-based carbon nanofibers is affected, and the fibers are transformed from a planar network structure to a distinct staggered three-dimensional network structure. These mutually cross-linked network structures can increase active sites, improve the tension and stability of cross-linked carbon nanofibers, and thus enhance the performance of the material; Figure 1 (d) and Figure 1 (e) It can be seen that the electrode modification material in Example 1 has an interlaced three-dimensional network structure of polyacrylonitrile-based carbon nanofibers.

[0131] 2. The electrode modification material UIO-66-NH2 / GO / PAN / CNFs in Example 1 was characterized using transmission electron microscopy (TEM):

[0132] Figure 2 is the TEM image of the electrode modification material in Example 1, Figure 2 It can be seen that UIO-66-NH2 is uniformly loaded on the surface of polyacrylonitrile-based carbon nanofibers.

[0133] Figure 3 The EDS distribution diagram of the electrode modification material C (a), O (b), N (c), and Zr (d) in Example 1 is shown in FIG. Figure 3It can be seen from the Mapping results that the electrode modification material in Example 1 is mainly composed of C, N, O and Zr elements, and several elements are evenly distributed in the fibers, indicating that UIO-66-NH2 is evenly distributed on the polyacrylonitrile-based carbon nanofibers.

[0134] 3. The electrode modification material UIO-66-NH2 / GO / PAN / CNFs in Example 1, the graphene oxide-doped polyacrylonitrile-based carbon nanofibers GO / PAN / CNFs in Comparative Example 2, and UIO-66-NH2 in Comparative Example 3 were characterized using a D8 ADVANCE Bruker X-ray diffractometer (XRD, Bruker, Germany):

[0135] Figure 4 XRD diffraction patterns of UIO-66-NH2, GO / PAN / CNFs and UIO-66-NH2 / GO / PAN / CNFs are shown in Figure 2. Figure 4 It can be seen that UIO-66-NH2 has diffraction peaks at 7.3° and 8.5°, which are attributed to the (110) and (200) crystal planes of UIO-66-NH2, indicating that UIO-66-NH2 nanoparticles with high crystallinity are successfully synthesized. The XRD diffraction pattern of UIO-66-NH2 / GO / PAN / CNFs is highly similar to that of UIO-66-NH2, indicating that UIO-66-NH2 is successfully loaded on GO / PAN / CNFs through solvothermal reaction.

[0136] 4. The electrode modified material UIO-66-NH2 / GO / PAN / CNFs in Example 1 was characterized using an ESCALAB 250Xi X-ray photoelectron spectrometer (XPS, Thermo Fisher Scientific, USA):

[0137] Figure 5 This is the XPS graph of the electrode modified material in Example 1. Figure 6 This is the C1s characteristic peak spectrum of the electrode modification material in Example 1. Figure 7 This is the N1s characteristic peak spectrum of the electrode modification material in Example 1. Figure 8 This is the O1s characteristic peak spectrum of the electrode modification material in Example 1. Figure 9 This is the Zr3d characteristic peak spectrum of the electrode modification material in Example 1. Figures 5-9It can be seen that C in UIO-66-NH2 / GO / PAN / CNFs mainly exists in four forms: C=C (284.70eV), CO (286.06eV), CN (287.12eV) and OCO / C=O (288.80eV); N in UIO-66-NH2 / GO / PAN / CNFs mainly exists in pyridinic N (399.4eV), pyrrolic N (400.5eV), graphitic N (284.70eV), and OCO / C=O (288.80eV). The main forms of O in UIO-66-NH2 / GO / PAN / CNFs are Zr-O (530.20 eV), CO (530.6 eV) and C=O (532.5 eV). The main forms of Zr in UIO-66-NH2 / GO / PAN / CNFs are Zr 3d 5 / 2 (182.96 eV) and Zr 3d 3 / 2 (185.40eV) exists in two forms.

[0138] Figure 10 For Ru(bpy)3 in Application Example 5 2+ The CV curves of the -LIN system on different working electrodes are given by Figure 10 It can be seen that compared with other modified electrodes, Ru(bpy)3 2+ The oxidation current of the -LIN system on UIO-66-NH2 / GO / PAN / GCE increased significantly, but its position hardly changed.

[0139] Figure 11 For Ru(bpy)3 in Application Example 5 2+ -LIN system ECL curves on different working electrodes Figure 11 It can be seen that Ru(bpy)3 2+ The ECL luminescence intensity of the -LIN system is significantly increased on UIO-66-NH2 / GO / PAN / CNFs / GCE, which is about 15 times that of the GCE bare electrode, indicating that UIO-66-NH2 / GO / PAN / CNFs / GCE is effective for Ru(bpy)3 2+ -LIN system has a significant sensitization effect. During the enhancement process, Ru(bpy)3 2+ Oxidized to Ru(bpy)3 3+ The nitrogen in the tertiary amino group of lincomycin is oxidized to an N-cation radical. Since the radical is extremely unstable, it will immediately dehydrogenate to generate a strong reducing intermediate LIN*, which will convert Ru(bpy)3 3+ Reduction to excited state Ru(bpy)3 2+ *, when the excited state Ru(bpy)32+ *Return to the ground state Ru(bpy)3 2+ The large specific surface area of ​​UIO-66-NH2 / GO / PAN / CNFs / CNFs provides more active sites for the reaction, which helps lincomycin diffuse on the electrode surface and accelerates the electron transfer rate.

[0140] The present invention uses an electrochemiluminescence sensor containing a chemically modified working electrode to detect lincomycin in milk. Table 1 compares the detection limit and linear range of this method with other existing lincomycin detection methods. As shown in Table 1, the detection limit of the lincomycin electrochemiluminescence detection method provided by the present invention is 5.61×10 -10 mol / L, linear range is 1.0×10 -8 -1×10 -4 mol / L, compared with existing detection methods such as mass spectrometry (LC-MS / MS) and common electrochemiluminescence (ECL), it has a lower detection limit and a wider linear range.

[0141] Table 1 Comparison of detection limits and linear ranges of lincomycin detection methods

[0142] Method Linear range (mol / L) Limit of detection (mol / L) Liquid chromatography (LC) <![CDATA[6.50×10 -6 -3.25×10 -4 ]]> <![CDATA[5.2×10 -8 ]]> Liquid chromatography-tandem mass spectrometry (LC-MS / MS) <![CDATA[1.08×10 -8 -2.17×10 -7 ]]> 4.3 x 10 -10 ]]> Capillary electrophoresis-amperometric detection (CZE-AD) <![CDATA[2.17×10 -6 -3.25×10 -4 ]]> 2.17 x 10 -6 ]]> Electrochemiluminescence (ECL) <![CDATA[5.0×10 -6 -1.0×10 -4 ]]> <![CDATA[3.10×10 -6 ]]> High performance liquid chromatography-ultraviolet (HPLC-UV) <![CDATA[1.74×10 -7 -4.34×10 -6 ]]> <![CDATA[4.33×10 -8 ]]> Linear sweep voltammetry (LSV) <![CDATA[4.5×10 -7 -1.5×10 -4 ]]> <![CDATA[2.0×10 -7 ]]> The present invention <![CDATA[1.0×10 -8 -1.0×10 -4 ]]> 5.61 x 10 -10 ]]>

[0143] In addition, in order to test the reliability of the detection result of the electrochemiluminescence sensor containing the chemically modified working electrode, the chemically modified electrode UIO-66-NH2 / GO / PAN / CNFs / GCE prepared in Application Example 1 was used to detect lincomycin in milk for 8 times, and the ECL signal intensity was 1096.35 a.u., 1150.51 a.u., 1177.6 a.u., 1151.54 a.u., 1146.48 a.u., 1167.57 a.u., 1218.73 a.u. and 1139.51 a.u. respectively, and the relative standard deviation (RSD) of 8 detections was about 3.16%, indicating that the chemically modified electrode UIO-66-NH2 / GO / PAN / CNFs / GCE had good repeatability; then 8 chemically modified electrodes were prepared again according to the method in Application Example 1, and were used to detect lincomycin in milk respectively, and the ECL signal intensity was 1144.52 a.u., 1183.64 a.u., 1117.48 a.u., 1101.39 a.u., 1141.52 a.u., 1122.44 a.u., 1172.6 a.u. and 1210.72 a.u. respectively, and the RSD value of the ECL intensity obtained by 8 detections was about 3.38%, indicating that the chemically modified electrode prepared in the application had good reproducibility. The recovery of lincomycin in milk was 93.72%-104.70% (RSD<5%), and the detection result had high accuracy, indicating that the chemically modified electrode and the electrochemiluminescence sensor with the chemically modified electrode as the working electrode provided by the application were suitable for the detection of lincomycin in milk, and had the advantages of rapid detection, high detection sensitivity, low cost, simple sample processing and reliable detection result.

Claims

1. An electrode modification material, characterized in that The electrode modification material includes graphene oxide-doped polyacrylonitrile-based carbon nanofibers and UIO-66-NH2; the UIO-66-NH2 is loaded on the surface of the graphene oxide-doped polyacrylonitrile-based carbon nanofibers; The electrode modification material is prepared by a method comprising the following steps: S1, mixing polyacrylonitrile, graphene oxide and a solvent to form a precursor solution, and electrospinning to obtain graphene oxide-doped polyacrylonitrile fibers; S2. carbonizing the graphene oxide-doped polyacrylonitrile fibers to obtain graphene oxide-doped polyacrylonitrile-based carbon nanofibers; S3. Mixing a zirconium source, an organic ligand and a solvent to form UIO-66-NH2, adding graphene oxide-doped polyacrylonitrile-based carbon nanofibers to form a suspension, heating the suspension to react, and obtaining the electrode modification material.

2. The electrode modifying material according to claim 1, characterized in that The zirconium source is selected from at least one of zirconium chloride, zirconium acetate, and zirconium sulfate; and / or, the organic ligand is 2-aminoterephthalic acid; And / or, the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

3. The electrode modifying material according to claim 1, characterized in that In step S1, the ratio of graphene oxide, polyacrylonitrile and solvent is 1 g: (10-15) g: (25-35) mL; And / or, the electrospinning process parameters include at least one of the following parameters: 1) The needle distance is 15-20cm; 2) The speed of the winding drum is 160-220r / min; 3) Voltage is 11-15kV; 4) The injection rate is 1-2 mL / h.

4. The electrode modifying material according to claim 1, characterized in that In step S2, the carbonization includes firstly o C / min and heat up to 200-250 o C, keep warm for 2-3 hours for pre-oxidation, and then heat for 5-10 o C / min and heat up to 600-800 o C, keep warm for 3-5h.

5. The electrode modifying material according to claim 1, characterized in that In step S3, the ratio of the zirconium source, the organic ligand, and the solvent is 1 g: (1-1.3) g: (60-120) mL; And / or, the mass ratio of the zirconium source to the graphene oxide-doped polyacrylonitrile-based carbon nanofibers is 1: (0.1-1.5); And / or, the heating reaction temperature is 100-120° C. and the time is 12-18 hours.

6. A chemically modified electrode, characterized in that The surface of the chemically modified electrode carries the electrode modification material according to any one of claims 1 to 5.

7. An electrochemiluminescence sensor, characterized in that Comprising the chemically modified electrode according to claim 6.

8. Use of the chemically modified electrode according to claim 6 or the electrochemiluminescence sensor according to claim 7 in the detection of lincomycin.

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