A metal ion-doped nickel oxyhydroxide electrode material, the modified electrode thereof, and a regeneration method

Abstract

The present invention provides a metal ion-doped nickel oxyhydroxide electrode material, an electrode modified thereby, and a regeneration method. The preparation method of the electrode material includes: (1) providing solution A, solution B, and solution C; wherein, solution A is formed by dissolving a nickel salt and other metal salts in solvent A; solution B is formed by dissolving a conductive substance in solvent B; solution C is formed by dissolving a reducing agent in water; (2) mixing and stirring solution A, solution B, and solution C, and then evaporating the solvent to obtain a preliminary product; (3) subjecting the preliminary product obtained in step (2) to high-temperature calcination to obtain the metal ion-doped nickel oxyhydroxide electrode material. Its synthesis raw materials are easily available and inexpensive; during the repeated use of the electrode modified thereby, the electrode regeneration step is simple, and only an oxidation potential needs to be applied by an electrochemical workstation, and the electrode can be completely regenerated in 60 seconds; after multiple uses, the loss rate of the electrode material is low.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode material regeneration, and particularly relates to a nickel oxyhydroxide electrode material doped with metal ions, an electrode modified thereby, and a regeneration method. Background Art

[0002] Due to their characteristics such as fast response, high sensitivity, low cost, and good selectivity in complex samples, electrochemical sensors have received widespread attention and are widely used in fields such as medical diagnosis, food safety detection, and environmental monitoring. In electroanalytical detection, due to the non-specific adsorption of interfering substances in the detection sample, the working electrode tends to become passivated, affecting the detection effect and even resulting in false positives in detection. Usually, for the repeated use of the electrode, a series of treatments need to be carried out on the electrode. For example: 1) Using sandpaper to polish, but the process is cumbersome and time-consuming, and it is necessary to use cyclic voltammetry to test whether the polished electrode meets the detection standard. 2) Reconstructing biorecognition elements, signal amplification materials, etc. on the electrode surface, but the preparation cost of these materials is relatively high, and at the same time, these treatment processes are cumbersome and time-consuming, which will introduce human errors and lead to poor repeatability of detection. Therefore, it is necessary to design a renewable electrode with advantages such as good stability, easy preparation, reusable, and sensitive detection.

[0003] In the prior art, Document 1 (Yao T., Feng J.J., Ma Z.F., Han H.L., Chemical Engineering Journal 2022, 439, 135599.) reported a detection platform for realizing rapid reagent-free electrode regeneration based on electrooxidation-mediated host-guest dissociation. Cyclodextrin adsorbs ferrocene on the electrode through host-guest recognition. The guest molecule ferrocene, as a signal substance, is released from the cyclodextrin host within 3 minutes at a controlled oxidation potential to eliminate the electrochemical signal, thereby realizing the regeneration of the detection platform. Using this strategy, this work constructed an immunoassay method for detecting squamous cell carcinoma. Its platform is easy to regenerate, without additional regenerants, and the detection limit reaches 31.20 fg mL -1 , and the regeneration times of a single electrode are seven times.

[0004] However, the above regeneration technology still has the following defects: 1) After multiple repeated uses, the material loss rate is high, the number of reusable times is only seven times, and the regeneration times are low. 2) The method of clearing the guest molecules in the host cavity by electrochemical oxidation is not thorough enough to achieve complete regeneration.

[0005] Another type of regeneration technology literature II (Peng L.C., Yuan Y.L., Fu X.M., Fu A., Zhang P., Chai Y.Q., Gan X.X., and Yuan R., Analytical Chemistry, 2019, 91, 3239 - 3245.) is a regeneration strategy based on DNA strand displacement reaction. In the presence of ferrocene-labeled DNA (Fc-DNA), DNA labeled with diethylenetriamine (DETA) switches clockwise to the "off" state based on the strand displacement reaction, resulting in significant electrochemiluminescence quenching of the Ru(II) system. Next, by using miRNA-21 as the driving fuel, the configuration of the DNA scissors can be switched counterclockwise. Due to the release of Fc-DNA and the proximity between DETA and the Ru(II) complex, this greatly enhances the electrochemiluminescence intensity of the Ru(II) complex. The reversible switching of the DNA scissors leads to a significant enhancement of the ECL signal, enabling sensitive and reproducible detection of miRNA-21 with a detection limit of 0.17 fM, which has also been successfully applied to the detection of miRNA in different cancer cells.

[0006] However, the above regeneration technology still has the following defects: 1) The electrode regeneration time is long; 2) The preparation cost of the detection element at the electrode interface is too high; 3) The number of regeneration times is also low, and it can only be regenerated four times.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] To address the above problems, the present invention designed and synthesized a novel electrode material "metal ion-doped nickel oxyhydroxide", which has easily available and inexpensive synthesis raw materials; during the repeated use of the electrode modified with it, the electrode regeneration step is simple, and only an oxidation potential needs to be applied using an electrochemical workstation, and the electrode can be completely regenerated in 60 seconds; after multiple uses, the loss rate of the electrode material is low; according to the regulation of the metal ion-doped nickel oxyhydroxide loading on the electrode, the number of regeneration times of the renewable electrode can also be regulated, and theoretically, the number of regeneration times can reach tens of thousands. It solves the problem of poor detection repeatability caused by human error due to the complicated and time-consuming pretreatment operations of the electrode. It solves the problem of resource waste caused by the small number of electrode regeneration times. It solves the problem of the long electrode regeneration time.

[0009] One of the objectives of the present invention is to provide a method for preparing a metal ion-doped nickel oxyhydroxide electrode material.

[0010] Another objective of the present invention is to provide a metal ion-doped nickel oxyhydroxide electrode material prepared by this method.

[0011] A third object of the present invention is to provide an electrode modified with the nickel oxyhydroxide electrode material doped with metal ions.

[0012] A fourth object of the present invention is to provide a method for regenerating the electrode.

[0013] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0014] In a first aspect, the present invention provides a method for preparing a nickel oxyhydroxide electrode material doped with metal ions, comprising the following steps:

[0015] (1) Provide solution A, solution B and solution C;

[0016] Among them, solution A is formed by dissolving a nickel salt and other metal salts in solvent A;

[0017] Solution B is formed by dissolving a conductive substance in solvent B;

[0018] Solution C is formed by dissolving a reducing agent in water;

[0019] (2) Mix and stir solution A, solution B and solution C, and then evaporate the solvent to obtain a primary product;

[0020] (3) Calcinate the primary product obtained in step (2) at high temperature to obtain a nickel oxyhydroxide electrode material doped with metal ions.

[0021] The following is a detailed description of each step.

[0022] Step (1)

[0023] In this step, the nickel salt of solution A can be at least one selected from nickel nitrate hexahydrate, nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, and preferably nickel nitrate hexahydrate.

[0024] The other metal salts of solution A refer to salts containing metals other than nickel, and can be metal salts selected from those containing zinc, calcium, sodium, potassium, magnesium, aluminum, manganese, iron, etc., and preferably zinc salts. The zinc salt can be at least one selected from zinc nitrate hexahydrate, zinc acetate, and zinc sulfate.

[0025] Solvent A can be at least one selected from deionized water, ethanol, and methanol.

[0026] In some embodiments, in solution A, the molar mass ratio (or molar ratio) of the other metal element to the nickel element is 0.25-1, and preferably 1.

[0027] In some embodiments, in Solution A, the total molar concentration (or molarity) of other metal elements and nickel element is 0.1 - 0.3 mol / L, such as 0.125 mol / L, 0.15 mol / L, 0.2 mol / L.

[0028] In this step, the conductive substance of Solution B can be a substance with excellent electrical conductivity selected from multi-walled carbon nanotubes, graphene, metal nanoparticles (such as gold, silver, etc.), or conductive polymer polymers, etc., and more preferably multi-walled carbon nanotubes.

[0029] Solvent B can be at least one selected from deionized water, ethanol, and methanol.

[0030] In some embodiments, the ratio of the mass of the conductive substance to the volume of Solvent B is 0.1 - 10 g : 0.1 - 100 mL, such as 0.1 g : 10 mL.

[0031] In this step, the reducing agent of Solution C can be at least one selected from sodium citrate and sodium borohydride, and more preferably sodium citrate.

[0032] In some embodiments, the ratio of the molar mass of the reducing agent to the volume of water (i.e., molar concentration, or molarity) is 0.1 - 1 mmol : 0.1 - 100 mL, such as 0.3 mmol : 5 mL.

[0033] Step (2)

[0034] In this step, the volume ratio of the addition of Solution A, Solution B, and Solution C can be 3 - 5 : 1 - 3 : 1 - 2, and preferably 4 : 2 : 1.

[0035] The evaporation solvent can be heated to an evaporation to a viscous state, at a temperature between 10 - 100 °C, preferably 60 °C.

[0036] Step (3)

[0037] In this step, the temperature of the high-temperature calcination can be 100 - 800 °C, preferably 200 °C; and / or

[0038] The time of the high-temperature calcination can be 1 - 24 hours.

[0039] In a second aspect, the present invention provides a metal ion-doped nickel oxyhydroxide electrode material prepared by the above method.

[0040] The electrode material synthesized by the present invention dopes metal ions (such as zinc, potassium, calcium, sodium, magnesium, manganese, iron, etc.) in nickel oxyhydroxide, enabling such materials to have the property of being reusable under electrochemical techniques.

[0041] By applying a reduction potential to the electrode material "metal ion-doped nickel oxyhydroxide", the metal ions (such as zinc ions) are reduced to metal elements (such as zinc elements) on the electrode surface. A linear relationship is established between the substance to be detected and the acid. When the acid converted from the substance to be detected is dripped onto the electrode containing the metal element (such as zinc element), the metal element (such as zinc element) is partially dissolved, and the signal of the remaining zinc element is detected under the electrochemical workstation. After the detection is completed, an oxidation potential is applied again to oxidize the metal element (such as zinc element) into metal ions (such as zinc ions), so that it enters the electrode material to re-enrich the metal ions (such as zinc ions); when the next detection is performed, a reduction potential is applied again to obtain the metal element (such as zinc element), so as to achieve the purpose of reusing the electrode.

[0042] In a third aspect, the present invention provides a metal ion-doped nickel oxyhydroxide electrode, which is obtained by modifying the above-mentioned metal ion-doped nickel oxyhydroxide electrode material.

[0043] Preferably, the specific preparation method of the metal ion-doped nickel oxyhydroxide electrode comprises:

[0044] The metal ion-doped nickel oxyhydroxide electrode material is mixed with a Nafion solution, drop-coated on an electrode, and dried to obtain an electrode.

[0045] In a fourth aspect, the present invention provides a method for regenerating the above-mentioned metal ion-doped nickel oxyhydroxide electrode, comprising the following steps:

[0046] Applying a reduction potential to the metal ion-doped nickel oxyhydroxide electrode before use, so that the metal ions in the metal ion-doped nickel oxyhydroxide are reduced to metal elements on the electrode surface;

[0047] After use, an oxidation potential is applied to the metal ion-doped nickel oxyhydroxide electrode to oxidize the metal element on the electrode surface into metal ions that enter the nickel oxyhydroxide, thereby completing electrode regeneration.

[0048] The oxidation and reduction potentials of different metal ions can be adjusted accordingly.

[0049] As can be seen from the table given by ICP-MS, after the zinc-doped nickel oxyhydroxide at 5 mg / mL is repeatedly regenerated 100 times on the electrode, the loss of zinc ions is only 1.177%. Then, it can be calculated that when the electrode loses its regeneration ability, that is, when all zinc ions are consumed, the electrode can be reused about 8,500 times. From this, it can be known that the zinc-doped nickel oxyhydroxide at 5 mg / mL can be reused about 8,500 times. Then, the zinc-doped nickel oxyhydroxide with a unit concentration (1 mg / mL) can be reused about 1,700 times on the electrode, and the zinc-doped nickel oxyhydroxide at 0.58 μg / mL can be reused once. Based on this, by loading zinc-doped nickel oxyhydroxide with different concentrations on the electrode, the regeneration times can be regulated.

[0050] Advantageous effects

[0051] (1) The metal ion-doped nickel oxyhydroxide prepared by the method of the present invention and its modified electrode have excellent repeatability, significantly improving many problems caused by electrode regeneration in the electrochemical sensing system, such as long regeneration time, low regeneration efficiency, and serious waste of regeneration materials. The metal ion-doped nickel oxyhydroxide can be reused, and the electrode can be regenerated by an extremely simple electrochemically redox method within one minute. According to the regulation of the loading amount of the metal ion-doped nickel oxyhydroxide on the electrode, the regeneration times of the renewable electrode can also be regulated, and theoretically, the regeneration times can reach tens of thousands of times.

[0052] (2) When used in electrochemical sensors, it has broad application prospects in the fields of biological detection, disease diagnosis, food hygiene, etc.

[0053] The present invention has been described in detail above, but the above embodiments are essentially only illustrative and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the foregoing prior art or the invention content or the following examples.

[0054] Unless otherwise expressly stated, the numerical ranges in the entire application document include any sub-ranges therein and any numerical values increasing in the smallest sub-units of the given values therein. Unless otherwise expressly stated, the numerical values in the entire application document represent an approximate measure or limitation of the scope of embodiments including minor deviations from the given values and having approximately the mentioned values and having the exact values mentioned. Except for the working examples provided at the end of the detailed description, all numerical values of parameters (such as quantities or conditions) in this application document (including the appended claims) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" means that the stated numerical value allows for some slight imprecision (some closeness to exactness in the value; approximately or reasonably close to the value; approximate). If the imprecision provided by "about" is not understood in this ordinary meaning in the art, then "about" as used herein means at least the variations that can be produced by the ordinary methods of measuring and using these parameters. For example, "about" can include variations of less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1% or less than or equal to 0.5%. Description of the Drawings

[0055] Figure 1 It is the graph of the electrode reusability performance in Example 1;

[0056] Figure 2 It is the X-ray photoelectron spectroscopy graph of nickel oxyhydroxide doped with zinc in Example 2;

[0057] Figure 3 It is the high-resolution transmission graph of nickel oxyhydroxide in the nickel oxyhydroxide material doped with zinc in Example 2;

[0058] Figure 4 It is the high-resolution transmission graph of the conversion of zinc ions to zinc metal after applying a reduction potential in the nickel oxyhydroxide material doped with zinc in Example 2;

[0059] Figure 5 It is the standard curve graph of the electrochemical signal and the concentration of the tumor marker in the application example. Detailed Description of the Invention

[0060] The following examples are merely listed as examples of the embodiments of the present invention and do not constitute any limitation to the present invention. Those skilled in the art can understand that modifications within the scope not deviating from the essence and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0061] The reagents and solvents disclosed below were purchased from Sigma-Aldrich China and are all of analytical grade. The ultrapure water used in the experiments was obtained through a Pasterika PSDK-30-E ultrapure water system.

[0062] X-ray photoelectron spectroscopy (XPS) data were measured by an Escalab 250, Thermofisher series in the United States; electrochemical tests were measured by a CHI 660E electrochemical workstation series from Shanghai Chenhua Instrument Co., Ltd. High-resolution transmission images were measured by a JEM-ARM200F series from JEOL.

[0063] Unless otherwise specified, the experimental methods used were all conventional methods.

[0064] Example 1 Synthesis of Zinc-Doped Nickel Hydroxide Oxide and Regeneration of Its Modified Electrode

[0065] Solution A: 0.149 g of zinc nitrate hexahydrate and 0.581 g of nickel nitrate hexahydrate were dissolved in 20 mL of water to prepare a solution.

[0066] Solution B: 0.1 g of multi-walled carbon nanotubes was dissolved in 10 mL of water to prepare a solution.

[0067] Solution C: 0.0756 g of citric acid was dissolved in 5 mL of water to prepare a solution.

[0068] 20 mL of Solution A, 10 mL of Solution B, and 5 mL of Solution C were mixed, stirred, and allowed to stand for at least 12 hours, and then the solvent was evaporated to obtain a crude product; the obtained crude product was placed in a tube furnace and calcined at 200 °C for 1 hour to obtain zinc-doped nickel hydroxide oxide, denoted as Zn 0.25 NiOOH, where 0.25 represents that the molar mass ratio of zinc element to nickel element is 0.25;

[0069] The obtained product was ground, and 5 mg of Zn 0.25 NiOOH was mixed with 30 μL of Nafion solution, 670 μL of ethanol, and 300 μL of isopropanol, ultrasonicated to obtain an electrode solution, and then dropped onto the electrode to obtain a zinc-doped nickel hydroxide oxide modified electrode.

[0070] Electrode regeneration method:

[0071] Apply a reduction potential of -1.6 V (versus silver / silver chloride electrode) to reduce zinc ions in the zinc-doped nickel hydroxide oxide to zinc metal on the electrode surface. Subsequently, apply an oxidation potential of -1.2 V (versus silver / silver chloride electrode) to oxidize the zinc metal on the electrode surface to zinc ions and enter the nickel hydroxide oxide to complete the repeated use of the electrode.

[0072] The zinc ions in the zinc-doped nickel oxyhydroxide can also be replaced by other metal ions, such as potassium, calcium, sodium, magnesium, manganese, iron, etc. After replacing the metal ions, it is only necessary to adjust the oxidation and reduction potentials accordingly.

[0073] Figure 1 This is a graph of the electrode reuse performance in this embodiment, from which it can be seen that after repeated use for many consecutive times, the oxidation peak intensity of the zinc element of the electrode is very stable.

[0074] The specific test steps are:

[0075] 20 μL of the above electrode solution was loaded on the electrode, and the electrode was connected to the working electrode end of the three-electrode system of the electrochemical workstation. In addition, the reference electrode end of the three-electrode system was a silver / silver chloride electrode, and the counter electrode end was a platinum wire electrode.

[0076] Figure 1 Operation when the number of cycles is 0: First, input the square wave voltammetry command to the electrochemical workstation, and the potential range is -1.6V to -1.2V. At this time, the zinc on the electrode is in an ionic state, and the square wave voltammetry cannot scan the signal of zinc oxidation, so the initial zinc oxidation current is extremely low.

[0077] Subsequently, a reduction potential of -1.6 V (vs. silver / silver chloride electrode) was applied for 60 seconds, so that the zinc ions in the zinc-doped nickel oxyhydroxide were partially reduced to zinc element on the electrode surface.

[0078] Figure 1 Operation when the number of cycles is 1: In the current state, input the square wave voltammetry command to the electrochemical workstation, the potential range is -1.6V to -1.2V. At this time, the zinc on the electrode is in a single state, and the square wave voltammetry scans the zinc oxidation signal, so the zinc oxidation current is extremely large.

[0079] Then, an oxidation potential of -1.2 V (relative to silver / silver chloride electrode) is applied for 60 seconds, so that the part of the zinc-doped nickel oxyhydroxide that is partially reduced to zinc element on the electrode surface is completely oxidized to zinc ions. According to the principle of electrostatic attraction, the zinc in the ionic state will re-enter the nickel oxyhydroxide, and the electrode has completed a cycle.

[0080] Figure 1 Operation when the number of cycles is 1': Enter the square wave voltammetry command again, and the potential range is -1.6V to -1.2V. At this time, the zinc on the electrode is already in an ionic state, and the square wave voltammetry method cannot scan the signal of zinc oxidation, so the zinc oxidation current is still very low after one cycle.

[0081] The cycle continues in this way.

[0082] Example 2

[0083] Except that the mass of zinc nitrate hexahydrate in solution A was 0.298 g, zinc-doped nickel oxyhydroxide was prepared in the same manner as in Example 1, denoted as Zn 0.5 NiOOH, where 0.5 represents that the molar mass ratio of zinc element to nickel element is 0.5. In addition, the regeneration steps of the electrode modified with zinc-doped nickel oxyhydroxide were also carried out in the same manner as in Example 1.

[0084] Figure 2 This is the X-ray photoelectron spectroscopy pattern of zinc-doped nickel oxyhydroxide in this example. Peaks corresponding to the elements can be observed in the spectrum, indicating that the sample contains the expected elements. It can be seen from the figure that the material obtained by the preparation method according to the present invention contains C, N, Zn, and Ni elements.

[0085] Figure 3 This is the high-resolution transmission image of nickel oxyhydroxide in the zinc-doped nickel oxyhydroxide material in this example. The lattice fringes of the (006) crystal plane of nickel oxyhydroxide crystals can be observed in the spectrum. Combining Figure 2 it can prove the successful synthesis of the zinc-doped nickel oxyhydroxide material.

[0086] Figure 4 This is the high-resolution transmission image of zinc-doped nickel oxyhydroxide material after applying a reduction potential, where zinc ions are converted into zinc metal. The lattice fringes of the (002) crystal plane of zinc metal can be observed in the spectrum.

[0087] Table 1 shows the zinc ion content table of the zinc-doped nickel oxyhydroxide material in this example before and after 100 regenerations on the electrode, tested by inductively coupled plasma mass spectrometry (ICP-MS). The test method for zinc ion content is as follows: accurately weigh the sample into a 50 ml digestion container, add 8 ml of aqua regia and 1 ml of hydrogen peroxide, place it on a graphite heating plate at 120 - 200 °C for digestion for 120 - 180 minutes, continuously add the above acid during the process until the sample is completely digested, filter after the acid cools, and make up the volume to a volumetric flask for instrument testing. After 100 repeated regenerations, the zinc ions only lost 1.77%. It can be seen from the table that the electrode modified with the material obtained by the preparation method according to the present invention has a very large number of renewable times.

[0088] Table 1

[0089]

[0090] Example 3

[0091] Except that the mass of zinc nitrate hexahydrate in solution A was 0.596 g, zinc-doped nickel oxyhydroxide was prepared in the same manner as in Example 1, denoted as Zn1NiOOH, where 1 represents that the molar mass ratio of zinc element to nickel element is 1.

[0092] In addition, the regeneration step of the zinc-doped nickel oxyhydroxide modified electrode is also carried out in the same manner as in Example 1.

[0093] Example 4

[0094] Except that zinc nitrate hexahydrate in solution A is changed to 0.126 g of manganese nitrate tetrahydrate, manganese-doped nickel oxyhydroxide is prepared in the same manner as in Example 1, denoted as Mn 0.25 NiOOH, where 0.25 represents that the molar mass ratio of manganese element to nickel element is 0.25.

[0095] The regeneration step of the manganese-doped nickel oxyhydroxide modified electrode is carried out as follows:

[0096] The obtained manganese-doped nickel oxyhydroxide product powder is ground, 5 mg is taken, mixed with 30 μL of Nafion solution, 670 μL of ethanol, and 300 μL of isopropanol, ultrasonicated, and then drop-coated on the electrode. A reduction potential of -1.9 V (relative to the silver / silver chloride electrode) is applied to reduce the zinc ions in the manganese-doped nickel oxyhydroxide to manganese metal on the electrode surface. Subsequently, an oxidation potential of -1.5 V (relative to the silver / silver chloride electrode) is applied to oxidize the manganese metal on the electrode surface to manganese ions and enter the nickel oxyhydroxide, completing the reuse of the electrode.

[0097] Example 5

[0098] Except that zinc nitrate hexahydrate in solution A is changed to 0.251 g of manganese nitrate tetrahydrate, manganese-doped nickel oxyhydroxide is prepared in the same manner as in Example 1, denoted as Mn 0.5 NiOOH, where 0.5 represents that the molar mass ratio of manganese element to nickel element is 0.5.

[0099] In addition, the regeneration step of the manganese-doped nickel oxyhydroxide modified electrode is also carried out in the same manner as in Example 4.

[0100] Example 6

[0101] Except that zinc nitrate hexahydrate in solution A is changed to 0.502 g of manganese nitrate tetrahydrate, manganese-doped nickel oxyhydroxide is prepared in the same manner as in Example 1, denoted as Mn1NiOOH, where 1 represents that the molar mass ratio of manganese element to nickel element is 1.

[0102] In addition, the regeneration step of the manganese-doped nickel oxyhydroxide modified electrode is also carried out in the same manner as in Example 4.

[0103] Application Example

[0104] The electrode modified with zinc-doped nickel oxyhydroxide obtained in Example 1 is used to detect the concentration of the tumor marker squamous cell carcinoma antigen (SCCA). The specific steps are as follows:

[0105] 1) Prepare carboxylated magnetite, and then connect the squamous cell carcinoma capture antibody (denoted as Ab1) to the carboxylated magnetite through bioconjugation technology, and block the remaining active sites (carboxyl groups) with bovine serum albumin to obtain immunomagnetic beads, denoted as Fe3O4@Ab1.

[0106] 2) Mix 1.4 M of dimethylimidazole, 1 mL of 20 mM zinc acetate and 50 μg of glucose oxidase together and stir overnight, then centrifuge and wash to obtain ZIF-8 wrapped with glucose oxidase, denoted as GOx@ZIF-8. Subsequently, gold particles wrapped GOx@ZIF-8 are prepared by in-situ reduction of chloroauric acid on the surface of ZIF-8 wrapped with glucose oxidase, denoted as GOx@ZIF-8@Au. Finally, mix the squamous cell carcinoma tag antibody (denoted as Ab2) with GOx@ZIF-8@Au and stir for three hours to obtain an immunoprobe, denoted as GOx@ZIF-8@Au@Ab2.

[0107] 3) Mix a series of standard concentration tumor marker solutions, the immunomagnetic beads described in step 1) and the immunoprobe described in step 2) respectively for sufficient mixing and incubation. After 10 to 30 minutes, perform magnetic separation to obtain an immunological sandwich structure magnetic separation substrate (i.e., immunomagnetic beads - squamous cell carcinoma antigen - immunoprobe). Add a certain concentration of glucose solution to the magnetic separation substrate, react for 1 to 30 minutes, take a certain amount of supernatant and drop it on the electrode modified with zinc-doped nickel oxyhydroxide prepared in Example 1, measure its electrochemical signal respectively, and make a standard curve of electrochemical signal vs. concentration, as Figure 5 shown;

[0108] 4) Incubate the tumor marker solution with unknown concentration and react according to step 3), and measure its electrochemical signal. Compare it with the corresponding standard curve in step 3), and the concentration of the tumor marker in the tumor marker solution to be measured can be obtained.

[0109] 5) For the used electrode, by applying an oxidation potential, the zinc element on the surface is re-oxidized into zinc ions, and when a reduction potential is applied again, it is reduced into zinc element to achieve the purpose of reusing the electrode.

[0110] In step 3), the sandwich structure magnetic separation substrate containing glucose oxidase can catalyze glucose to produce gluconic acid. Taking this supernatant and dropping it on the electrode can dissolve zinc element. Different concentrations of antigen cause changes in the concentration of the sandwich structure magnetic separation substrate, thereby causing changes in the acid concentration in the supernatant and the amount of dissolved zinc element.

[0111] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A regeneration method for a metal ion-doped nickel oxyhydroxide electrode, characterized in that, The following steps are involved: (1) Providing solution A, solution B and solution C; Wherein, solution A is formed by dissolving nickel salt and other metal salts in solvent A; Solution B is formed by dissolving the conductive substance in solvent B; Solution C is formed by dissolving the reducing agent in water; (2) Mixing and stirring solution A, solution B and solution C, and evaporating the solvent to obtain a primary product; (3) calcining the primary product obtained in step (2) at high temperature to obtain a metal ion-doped nickel oxyhydroxide electrode material; (4) mixing the metal ion-doped nickel oxyhydroxide electrode material with a Nafion solution, drop-coating the solution on an electrode, and drying the solution to obtain an electrode; Further comprising the steps of: Applying a reduction potential to the metal ion-doped nickel oxyhydroxide electrode so that the metal ions in the metal ion-doped nickel oxyhydroxide are reduced to metal elements on the electrode surface; Applying an oxidation potential to the nickel oxyhydroxide electrode doped with metal ions to oxidize the metal element on the surface of the electrode into metal ions that enter the nickel oxyhydroxide; The nickel salt of solution A is at least one selected from nickel nitrate hexahydrate, nickel sulfate, nickel chloride, nickel sulfamate and nickel bromide, and the other metal salts of solution A are selected from metal salts containing zinc, calcium, sodium, potassium, magnesium, aluminum, manganese or iron.

2. The regeneration method according to claim 1, characterized in that, In step (1), the nickel salt in solution A is nickel nitrate hexahydrate; The other metal salt in solution A is a zinc salt; The solvent A is at least one selected from deionized water, ethanol and methanol.

3. The regeneration method according to claim 1, characterized in that, In solution A, the ratio of the molar mass of other metal elements to the nickel element is 0.25~11.

4. The regeneration method according to claim 3, characterized in that, In solution A, the ratio of the molar mass of other metal elements to the molar mass of nickel element is 1.

5. The regeneration method according to claim 1, characterized in that, In solution A, the total molar mass concentration of other metal elements and nickel element is 0.1~0.3 mol / L.

6. The regeneration method according to claim 1, characterized in that, In step (1), the conductive material of solution B is selected from multi-walled carbon nanotubes, graphene, metal nanoparticles or conductive polymers; Solvent B is at least one selected from deionized water, ethanol, and methanol; The ratio of the mass of the conductive substance to the volume of the solvent B is 0.1-10 g: 0.1-100 mL.

7. The regeneration method according to claim 6, characterized in that, In step (1), the conductive material in solution B is multi-walled carbon nanotubes.

8. The regeneration method according to claim 1, characterized in that, In step (1), the reducing agent of solution C is at least one selected from sodium citrate and sodium borohydride; The ratio of the molar mass of the reducing agent to the volume of water is 0.1-1mmol: 0.1-100mL.

9. The regeneration method according to claim 8, characterized in that, In step (1), the reducing agent of solution C is sodium citrate.

10. The regeneration method according to claim 1, characterized in that, In step (3), the high temperature calcination temperature is 100-800°C; and The high temperature calcination time is 1 to 24 hours.

11. The regeneration method according to claim 10, characterized in that, In step (3), the high temperature calcination temperature is 200°C.

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