Preparation method and application of a single-atom indium enhanced dopamine electrochemical sensor

Abstract

The present invention relates to the field of biochemical electrode technology, in particular to the field of IPCG01N27, and more specifically to a method and application of preparing a single-atom indium enhanced dopamine electrochemical sensor. The preparation method comprises the following steps: step (1), using raw materials trimesic acid and indium tetrahydrate, synthesizing In‑MOF by a solvent thermal method; step (2), In‑MOF and dicyandiamide are calcined at a high temperature to obtain In1‑N‑C and In‑N‑C‑X powders; step (3), In1‑N‑C and In‑N‑C‑X powders are dispersed in a solvent to obtain suspended droplets; step (4), the suspended droplets are doped on a treated glassy carbon electrode, and In1‑N‑C and In‑N‑C‑X modified electrodes are obtained after drying. The electrochemical sensor prepared by the present invention can be applied to dopamine detection, and has the advantages of simple preparation method, high detection sensitivity, and high selectivity.

Description

Technical Field

[0001] The present invention relates to the field of biochemical electrode technology, in particular to the field of IPCG01N27, and more specifically to a preparation method and application of a single-atom indium enhanced dopamine electrochemical sensor. Background Art

[0002] Dopamine (DA), as an important neurotransmitter, can regulate many physiological functions of the central nervous system. Dysregulation of the DA system is associated with Parkinson's disease, schizophrenia, Tourette syndrome, attention deficit hyperactivity disorder, and pituitary tumors. Therefore, it is necessary to develop an advanced method for DA detection with high sensitivity and selectivity. Previously, many technologies, such as colorimetry, fluorescence, electrochemistry, and electrochemiluminescence, have been used for sensitive and selective detection of DA. Among them, electrochemical sensors have attracted great attention in recent years due to their advantages such as low cost, high sensitivity, and fast response speed. Graphene, precious metals, and metal oxidant electrocatalysts have been used to achieve the detection of trace targets. The sensitivity of electrochemical sensors is highly dependent on the catalytic performance of the electrocatalyst. Therefore, it is necessary to develop electrochemical catalysts with high catalytic activity to further improve the detection sensitivity.

[0003] CN201910183755.2 discloses a method for detecting dopamine using a nano-tungsten diselenide-modified gold electrode photoelectrochemical sensor. Using dichlorobenzene as a stripping agent, ultrasonically stripping tungsten diselenide to obtain nano-tungsten diselenide is used to modify an electrode. The enhanced photoelectrochemical signal of the nano-tungsten diselenide-modified electrode, utilising dopamine, enables highly sensitive dopamine detection. However, this method requires the use of a precious metal gold electrode, which increases costs. Furthermore, the gold electrode has poor adhesion, and the nano-tungsten diselenide may have defects in its adhesion to the gold electrode.

[0004] CN201310023869.3 discloses a method for preparing a gold nanoparticle-doped molecularly imprinted electrochemical sensor for detecting dopamine. This method combines the advantages of an electrochemical sensor and a gold nanoparticle-doped imprinted polymer to construct a gold nanoparticle-doped molecularly imprinted electrochemical sensor for detecting dopamine, thereby achieving high sensitivity and rapid detection of dopamine in biological samples. However, this method has complex sample processing and is time-consuming. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide an electrochemical catalyst with high catalytic activity for dopamine detection, which has the advantages of simple preparation method, high detection sensitivity and high selectivity.

[0006] To achieve the purpose of the present invention, the first aspect of the present invention provides a method for preparing a single-atom indium enhanced dopamine electrochemical sensor, comprising the following steps:

[0007] Step (1), using trimesic acid and indium tetrahydrate as raw materials to synthesize In-MOF (indium-based metal-organic framework) by a solvothermal method;

[0008] Step (2), calcining In-MOF and dicyandiamide at high temperature to obtain In1-NC and / or In-NCX powder;

[0009] Step (3), dispersing In1-NC and / or In-NCX powder in a solvent to obtain suspended droplets;

[0010] Step (4), drop the suspension onto the treated glassy carbon electrode, and after drying, obtain In-NC and In-NCX modified electrodes.

[0011] Preferably, the molar ratio of trimesic acid (CAS: 554-95-0) to indium tetrahydrate (CAS: 13770-61-1) is 1:(1.2-1.5).

[0012] More preferably, the molar ratio of trimesic acid to indium tetrahydrate is 1:1.33.

[0013] The solvent is one or more of dimethylformamide, methanol, dimethylacetamide, butanone, and ethanol.

[0014] To simplify post-processing steps and improve reaction efficiency, a mixture of dimethylformamide and methanol was selected as the solvent. At a volume ratio of 4:0.5-2, this mixed solvent provides a unique physical and chemical environment for the reaction and crystallization of trimesic acid and indium tetrahydrate, unattainable at normal pressure. This is likely due to the solvent's specific polarity, which enhances compatibility with the reactants and increases the probability of molecular collisions. Furthermore, the solvent's properties are more stable at higher temperatures, matching the reaction temperature. The reaction product, In-MOF, can be precipitated from the mixed solvent, promoting the forward reaction and allowing the product to be easily recovered by filtration.

[0015] Preferably, the solvent is dimethylformamide and methanol, and the volume ratio of dimethylformamide to methanol is 4:(0.5-2).

[0016] Further preferably, the solvent is dimethylformamide and methanol; the volume ratio of dimethylformamide to methanol is 4:1.

[0017] The reaction temperature is 100-130° C., and the reaction time is 12-36 hours.

[0018] Preferably, the reaction temperature is 120° C. and the reaction time is 24 h.

[0019] A sheet-structured catalyst (In-NCX) was prepared by calcination and annealing. The study found that indium nanoparticle catalysts (In-NCX) with different temperatures were obtained at calcination temperatures of 700°C, 800°C and 900°C. The catalysts were named In-NC-700, In-NC-800 and In-NC-900 according to the different calcination temperatures. As the calcination temperature increased, the valence state of indium in In-NCX increased. When the calcination temperature reached 1000°C, the indium in In-NCX was dispersed atomically to obtain an indium single atom catalyst (In1-NC). It may be that the annealing temperature can change the electronic structure of the indium atoms.

[0020] Preferably, the temperature of the high-temperature calcination in step 2 is 700-1000°C.

[0021] Further preferably, the temperature of the high temperature calcination in step 2 is 1000°C.

[0022] The surface of the glassy carbon electrode is relatively rough. In order to activate the surface of the glassy carbon electrode, the glassy carbon electrode needs to be polished beforehand. Studies have found that the use of 0.03-0.5μm ultrafine alumina can improve the polishing efficiency. After polishing, ultrasonic cleaning with deionized water and ethanol for 1-2 minutes can obtain the mirror surface of the glassy carbon electrode.

[0023] In order to improve the dispersion of In1-NC or In-NCX, the solution is selected as a compound of deionized water, ethanol and 5wt% Nafion. The use of deionized water and ethanol can improve the wettability of In1-NC or In-NCX, and at the same time control the appropriate drying rate to avoid surface unevenness caused by excessive drying. Further research found that the ratio of deionized water, ethanol and 5wt% Nafion is 49:50: (0.5-2). The addition of 5wt% Nafion can also improve electrode performance and protect the electrode. Nafion reduces the transport resistance of the substance and the resistance of the electrode, greatly improving the utilization rate of the loaded catalyst. At the same time, the polymer film formed after the Nafion solution is air-dried can also protect the electrode surface.

[0024] Preferably, the solution is deionized water, ethanol and 5 wt% Nafion, and the ratio of deionized water, ethanol and 5 wt% Nafion is 49:50:(0.5-2).

[0025] Further preferably, the solution comprises deionized water, ethanol and 5 wt% Nafion, and the ratio of deionized water, ethanol and 5 wt% Nafion is 49:50:1.

[0026] When In1-NC or In-NCX is dispersed in a solution with a concentration of 3-7 mg / ml, the In1-NC or In-NCX particles can be evenly dispersed on the surface of the glassy carbon electrode. When the amount of In1-NC or In-NCX is too small, the surface area of ​​the sensor is reduced, resulting in reduced sensitivity. When the concentration is too high, the In1-NC or In-NCX particles aggregate and interlayer defects are prone to occur. Further research found that when the solution concentration is 5 mg / ml, the dispersion time of the suspended droplets can be increased.

[0027] Preferably, the concentration of In1-NC or In-NCX dispersed in the solution is 3-7 mg / ml.

[0028] Further preferably, the concentration of In1-NC or In-NCX dispersed in the solution is 5 mg / ml.

[0029] Enzymes are highly efficient biocatalysts in nature. In1-NCs, with atomically dispersed catalytic sites, resemble certain metalloproteases. It's possible that mimicking the active sites of natural enzymes enhances catalytic activity, leading to efficient signal amplification.

[0030] Since In1-NC can catalyze the redox of ascorbic acid, uric acid and dopamine, it has applications as an electrochemical sensor. Figure 7 As shown in the figure, in the absence of dopamine (DA) on the In1-NC modified electrode, there is no redox peak in the cyclic voltammetry (CV) curve. In the presence of DA on the In1-NC modified electrode, however, fine redox peaks appear in the CV curve, which can be attributed to the oxidation and reduction of DA, indicating that In1-NC can catalyze the redox of DA.

[0031] The invention discloses an application of a single-atom indium enhanced electrochemical sensor, wherein the electrochemical sensor can be used to simultaneously detect ascorbic acid, uric acid and dopamine.

[0032] A single-atom indium enhanced electrochemical sensor is applied to the detection of dopamine, comprising the following steps:

[0033] S1, prepare electrolyte;

[0034] S2, prepare dopamine standard solution;

[0035] S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using In1-NC and In-NCX modified electrodes.

[0036] Preferably, the electrolyte is a 0.1 mol / L PBS aqueous solution with a pH of 7.0.

[0037] Preferably, the concentration of the dopamine standard solution is 100 μmol / L.

[0038] Beneficial effects:

[0039] 1. When the volume ratio of dimethylformamide to methanol is 4:(0.5-2), the post-processing steps can be simplified and the reaction efficiency can be improved.

[0040] 2. When the calcination temperature reaches 1000℃, the indium in In-NCX is dispersed atomically to obtain an indium single-atom catalyst (In1-NC), achieving efficient signal amplification.

[0041] 3. When the ratio of deionized water, ethanol and 5 wt% Nafion is 49:50:(0.5-2), the dispersion of In1-NC or In-NCX is improved and the utilization rate of the supported catalyst is increased.

[0042] 4. When the concentration of In1-NC or In-NCX is dispersed in a solution of 3-7 mg / ml, the In1-NC or In-NCX particles can be evenly dispersed on the surface of the glassy carbon electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a scanning electron microscope image of In-MOF.

[0044] Figure 2 This is a transmission electron microscope image of In-NC-700.

[0045] Figure 3 This is a transmission electron microscope image of In-NC-800.

[0046] Figure 4 This is a transmission electron microscope image of In-NC-900.

[0047] Figure 5 Transmission electron microscope image of In1-NC.

[0048] Figure 6 XPS spectra of In1-NC and In-NCX.

[0049] Figure 7 Dopamine (DA) was detected by cyclic voltammetry for the In1-NC sensor.

[0050] Figure 8 Dopamine (DA) was detected by differential pulse voltammetry for In1-NC and In-NCX.

[0051] Figure 9Simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) in In1-NCs by differential pulse voltammetry.

[0052] Figure 10 The durability of In1-NC catalytic activity towards dopamine (DA) was tested by differential pulse voltammetry, and the electrochemical activity retention rate after 1-6 days.

[0053] Figure 11 This is the curve of DA concentration and peak current value of differential pulse voltammetry response.

[0054] in Figure 6 and Figure 8 Among them, In-NCX: Indium nanoparticle catalysts with different temperatures were obtained by calcination temperatures of 700℃, 800℃ and 900℃. The catalysts were named In-NC-700, In-NC-800 and In-NC-900 according to the different calcination temperatures; In1-NC: Indium single atom catalyst obtained by calcination temperature of 1000℃. DETAILED DESCRIPTION

[0055] Example 1

[0056] A method for preparing a single-atom indium enhanced dopamine electrochemical sensor comprises the following steps:

[0057] Step (1), using trimesic acid and indium tetrahydrate as raw materials to synthesize In-MOF (indium-based metal-organic framework) by a solvothermal method;

[0058] Step (2), In-MOF and dicyandiamide are calcined at high temperature to obtain In1-NC powder.

[0059] Step (3), dispersing In1-NC powder in a solvent to obtain suspension droplets;

[0060] Step (4), drop the suspension onto the treated glassy carbon electrode and obtain an In1-NC modified electrode after drying.

[0061] The step (1) is specifically as follows: 59.48 mol of trimesic acid (CAS: 554-95-0) and 79.23 mol of indium tetrahydrate (CAS: 13770-61-1) are dissolved in a mixed solution of 48 ml of dimethylformamide and 12 ml of methanol. The solution is then transferred to a polytetrafluoroethylene reactor and reacted at 120°C for 24 hours. The mixture is centrifuged (8000 rpm, 3 min) to obtain a white precipitate, which is then washed three times with methanol to obtain the product In-MOF. Figure 1 This is a scanning electron microscope image of In-MOF.

[0062] The step (2) is specifically as follows: 100 mg of In-MOF and 300 mg of dicyandiamide (CAS: 461-58-5) are heated to 1000°C at a heating rate of 2°C / min in a nitrogen atmosphere, and calcined at 1000°C for 3 hours to obtain black powder In1-NC. Figure 5 The following is a transmission electron microscope image of In1-NC. Figure 6 Shown is the XPS spectrum of In1-NC.

[0063] The step (3) is specifically as follows: a glassy carbon electrode (Shanghai Xianren Instrument Co., Ltd.) was polished with 0.3 μm and 0.05 μm alumina polishing powders, and then ultrasonically cleaned with deionized water and ethanol for 2 minutes each to obtain a treated glassy carbon electrode. 100 mg of In1-NC was dispersed in a mixed solution consisting of 10 ml of deionized water, 9.8 ml of ethanol, and 0.2 ml of 5 wt% Nafion (purchased from Alpha) by ultrasonication, and magnetically stirred at 100 rpm for 3 hours.

[0064] The step (4) is specifically as follows: using a pipette to drop 5 μL of In1-NC suspension onto the treated glassy carbon electrode and drying it at 25° C. for 0.5 h.

[0065] A single-atom indium enhanced electrochemical sensor is applied to the detection of dopamine, comprising the following steps:

[0066] S1, prepare electrolyte;

[0067] S2, prepare dopamine standard solution;

[0068] S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using the prepared modified electrode.

[0069] The electrolyte is a 0.1 mol / L PBS aqueous solution with a pH of 7.0.

[0070] The concentration of the dopamine standard solution is 100 μmol / L. The solute in the dopamine standard solution is dopamine hydrochloride purchased from Sinopharm Group, and the solvent is the electrolyte.

[0071] Example 2

[0072] A method for preparing a single-atom indium enhanced dopamine electrochemical sensor comprises the following steps:

[0073] Step (1), using phthalic acid and indium tetrahydrate as raw materials to synthesize In-MOF (indium-based metal organic framework) by a solvothermal method;

[0074] Step (2), In-MOF and dicyandiamide are calcined at high temperature to obtain In-NC-700 powder.

[0075] Step (3), dispersing In-NC-700 powder in a solvent to obtain suspension droplets;

[0076] Step (4), dropwise doping the suspension onto the treated glassy carbon electrode, and drying to obtain an In-NC-700 modified electrode.

[0077] Step (1) specifically comprises dissolving trimesic acid (59.48 mol) and indium tetrahydrate (79.23 mol) in a mixture of 48 ml of dimethylformamide and 12 ml of methanol. The solution is then transferred to a polytetrafluoroethylene reactor and incubated at 120°C for 24 hours. The mixture is centrifuged to obtain a white precipitate, which is then washed three times with methanol to obtain the product, In-MOF.

[0078] The step (2) is specifically as follows: 100 mg of In-MOF and 300 mg of dicyandiamide (CAS: 461-58-5) are heated to 700°C at a heating rate of 2°C / min in a nitrogen atmosphere, and calcined at 700°C for 3 hours to obtain black powder In-NC-700. Figure 2 The following is a transmission electron microscope image of In-NC-700. Figure 6 Shown is the XPS spectrum of In-NC-700.

[0079] Step (3) is as follows: polishing a glassy carbon electrode (3 mm in diameter) with 0.3 μm and 0.05 μm alumina polishing powders, followed by ultrasonic cleaning with deionized water and ethanol for 2 minutes each, to obtain a mirror surface of the treated glassy carbon electrode. Next, 100 mg of In-NC-700 was ultrasonically dispersed in a mixed solution of 10 ml of deionized water, 9.8 ml of ethanol, and 0.2 ml of 5 wt% Nafion (available from Alpha), and magnetically stirred at 100 rpm for 3 hours.

[0080] The step (4) is specifically as follows: using a pipette to drop 5 μL of In-NC-700 suspension onto a clean glassy carbon electrode and drying it at 25° C. for 0.5 h.

[0081] A single-atom indium enhanced electrochemical sensor is applied to the detection of dopamine, comprising the following steps:

[0082] S1, prepare electrolyte;

[0083] S2, prepare dopamine standard solution;

[0084] S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using the prepared modified electrode.

[0085] The electrolyte is a 0.1 mol / L PBS aqueous solution with a pH of 7.0.

[0086] The concentration of the dopamine standard solution is 100 μmol / L. The solute in the dopamine standard solution is dopamine hydrochloride purchased from Sinopharm Group, and the solvent is the electrolyte.

[0087] Example 3

[0088] A method for preparing a single-atom indium enhanced dopamine electrochemical sensor comprises the following steps:

[0089] Step (1), using phthalic acid and indium tetrahydrate as raw materials to synthesize In-MOF (indium-based metal organic framework) by a solvothermal method;

[0090] Step (2), In-MOF and dicyandiamide are calcined at high temperature to obtain In-NC-800 powder.

[0091] Step (3), dispersing In-NC-800 powder in a solvent to obtain suspended droplets;

[0092] Step (4), dropwise doping the suspension onto the treated glassy carbon electrode, and drying to obtain an In-NC-800 modified electrode.

[0093] Step (1) specifically comprises dissolving trimesic acid (59.48 mol) and indium tetrahydrate (79.23 mol) in a mixture of 48 ml of dimethylformamide and 12 ml of methanol. The solution is then transferred to a polytetrafluoroethylene reactor and incubated at 120°C for 24 hours. The mixture is centrifuged to obtain a white precipitate, which is then washed three times with methanol to obtain the product, In-MOF.

[0094] The step (2) is specifically as follows: 100 mg of In-MOF and 300 mg of dicyandiamide (CAS: 461-58-5) are heated to 800°C at a heating rate of 2°C / min in a nitrogen atmosphere, and calcined at 800°C for 3 hours to obtain black powder In-NC-800. Figure 3 The following is a transmission electron microscope image of In-NC-800. Figure 6 Shown is the XPS spectrum of In-NC-800.

[0095] Step (3) is as follows: polishing a glassy carbon electrode (3 mm in diameter) with 0.3 μm and 0.05 μm alumina polishing powders, followed by ultrasonic cleaning with deionized water and ethanol for 2 minutes each, to obtain a mirror surface of the treated glassy carbon electrode. Next, 100 mg of In-NC-800 was ultrasonically dispersed in a mixed solution of 10 ml of deionized water, 9.8 ml of ethanol, and 0.2 ml of 5 wt% Nafion (available from Alpha), and magnetically stirred at 100 rpm for 3 hours.

[0096] The step (4) is specifically as follows: using a pipette to drop 5 μL of In-NC-800 suspension onto a clean glassy carbon electrode and drying it at 25° C. for 0.5 h.

[0097] A single-atom indium enhanced electrochemical sensor is applied to the detection of dopamine, comprising the following steps:

[0098] S1, prepare electrolyte;

[0099] S2, prepare dopamine standard solution;

[0100] S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using the prepared modified electrode.

[0101] The electrolyte is a 0.1 mol / L PBS aqueous solution with a pH of 7.0.

[0102] The concentration of the dopamine standard solution is 100 μmol / L. The solute in the dopamine standard solution is dopamine hydrochloride purchased from Sinopharm Group, and the solvent is the electrolyte.

[0103] Example 4

[0104] A method for preparing a single-atom indium enhanced dopamine electrochemical sensor comprises the following steps:

[0105] Step (1), using phthalic acid and indium tetrahydrate as raw materials to synthesize In-MOF (indium-based metal organic framework) by a solvothermal method;

[0106] Step (2), In-MOF and dicyandiamide are calcined at high temperature to obtain In-NC-900 powder.

[0107] Step (3), dispersing In-NC-900 powder in a solvent to obtain suspension droplets;

[0108] Step (4), dropwise doping the suspension onto the treated glassy carbon electrode, and drying to obtain an In-NC-900 modified electrode.

[0109] Step (1) specifically comprises dissolving trimesic acid (59.48 mol) and indium tetrahydrate (79.23 mol) in a mixture of 48 ml of dimethylformamide and 12 ml of methanol. The solution is then transferred to a polytetrafluoroethylene reactor and incubated at 120°C for 24 hours. The mixture is centrifuged to obtain a white precipitate, which is then washed three times with methanol to obtain the product, In-MOF.

[0110] The step (2) is specifically as follows: 100 mg of In-MOF and 300 mg of dicyandiamide (CAS: 461-58-5) are heated to 900°C at a heating rate of 2°C / min in a nitrogen atmosphere, and calcined at 900°C for 3 hours to obtain black powder In-NC-900. Figure 4 The following is a transmission electron microscope image of In-NC-900. Figure 6 Shown is the XPS spectrum of In-NC-900.

[0111] Step (3) is as follows: polishing a glassy carbon electrode (3 mm in diameter) with 0.3 μm and 0.05 μm alumina polishing powders, followed by ultrasonic cleaning with deionized water and ethanol for 2 minutes each, to obtain a mirror surface of the treated glassy carbon electrode. Next, 100 mg of In-NC-900 was ultrasonically dispersed in a mixed solution of 10 ml of deionized water, 9.8 ml of ethanol, and 0.2 ml of 5 wt% Nafion (available from Alpha), and magnetically stirred at 100 rpm for 3 hours.

[0112] The step (4) is specifically as follows: using a pipette to drop 5 μL of In-NC-900 suspension onto a clean glassy carbon electrode and drying it at 25° C. for 0.5 h.

[0113] A single-atom indium enhanced electrochemical sensor is applied to the detection of dopamine, comprising the following steps:

[0114] S1, prepare electrolyte;

[0115] S2, prepare dopamine standard solution;

[0116] S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using the prepared modified electrode.

[0117] The electrolyte is a 0.1 mol / L PBS aqueous solution with a pH of 7.0.

[0118] The concentration of the dopamine standard solution is 100 μmol / L. The solute in the dopamine standard solution is dopamine hydrochloride purchased from Sinopharm Group, and the solvent is the electrolyte.

[0119] Performance testing methods

[0120] 1. Cyclic voltammetry test for electrochemical active area: prepare 0.1 mol / L KCl containing 1 mmol / L [Fe(CN)6] 3– / 4– The electrochemical sensors prepared in Examples 1-4 were used to measure the electrochemical active area using cyclic voltammetry. The test results are shown in Table 1.

[0121] 2. Determination of the catalytic activity of dopamine by differential pulse voltammetry: The electrochemical activity was measured by differential pulse voltammetry using the electrochemical sensor prepared in Examples 1-4. The test curve is shown in FIG. Figure 8 As shown, the electrochemical sensor prepared in Example 1 has the best catalytic activity.

[0122] 3. Differential pulse voltammetry was used to simultaneously measure the catalytic activity of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The electrochemical activity was measured by differential pulse voltammetry using the electrochemical sensor prepared in Example 1. The concentrations of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were all 100 μmol / L, and the solvent was 0.1 mol / L PBS aqueous solution. Ascorbic acid and uric acid were purchased from Sinopharm Group. The test curve is shown in Figure 2. Figure 9 As shown, when DA, UA, and AA coexist in the sample, the three oxidation peaks at −0.05, 0.15, and 0.31 eV can be well distinguished, indicating that In1-NCs can be used for the simultaneous detection of DA, UA, and AA.

[0123] 4. The catalytic activity durability of dopamine (DA) was measured by differential pulse voltammetry. The electrochemical activity of the electrochemical sensor prepared in Example 1 was measured by differential pulse voltammetry after 1-6 days. Figure 10 As shown, the electrochemical sensor can maintain 92.3% of the electrochemical response after 6 days.

[0124] 5. Determine the relationship between the electrochemical sensor's response to dopamine (DA) concentration and current peak. Use the electrochemical sensor prepared in Example 1 to prepare 0-500 μmol / L DA solutions. Use differential pulse voltammetry to test the current peaks of dopamine (DA) at different concentrations. Figure 11 As shown, the curve is fitted and the curve equation is obtained as Y=3.3482+25.90034X, R 2 is 0.98, where X is the DA concentration (μmol / L), Y is the current peak (μA), and the detection limit is 0.279 μM.

[0125] Performance test data

[0126] Table 1

[0127] Example <![CDATA[Electrochemical active area (cm 2 )]]> Example 1 0.372 Example 2 0.317 Example 3 0.293 Example 4 0.276

Claims

1. A method for preparing a single-atom indium enhanced dopamine electrochemical sensor, characterized in that: The following steps are involved: Step (1), using trimesic acid and indium tetrahydrate as raw materials to synthesize In-MOF by a solvothermal method; Step (2), calcining In-MOF and dicyandiamide at high temperature to obtain In1-NC and / or In-NCX powder; Step (3), dispersing In1-NC and / or In-NCX powder in a solvent to obtain suspended droplets; Step (4), doping the suspended droplets on the treated glassy carbon electrode, and obtaining In1-NC and In-NCX modified electrodes after drying, where X is temperature.

2. The method for preparing a single-atom indium enhanced dopamine electrochemical sensor according to claim 1, characterized in that: The temperature of the high-temperature calcination in step (2) is 700-1000°C.

3. The method for preparing a single-atom indium enhanced dopamine electrochemical sensor according to claim 2, characterized in that: In1-NC is obtained when the high-temperature calcination in step (2) is 1000°C.

4. The method for preparing a single-atom indium enhanced dopamine electrochemical sensor according to claim 3, characterized in that: Indium in the In1-NC is dispersed atomically.

5. The method for preparing a single-atom indium enhanced dopamine electrochemical sensor according to claim 3, characterized in that: The concentration of the suspension droplets is 3-7 mg / mL.

6. An application of an electrochemical sensor prepared by the preparation method according to claim 1, characterized in that: The electrochemical sensor is used for simultaneously detecting ascorbic acid, uric acid and dopamine.

7. Use of the electrochemical sensor prepared by the preparation method according to claim 6, characterized in that: The method is applied to the detection of dopamine, and includes the following steps: S1, prepare electrolyte; S2, prepare dopamine standard solution; S3, catalytic activity of dopamine was determined by cyclic voltammetry and differential pulse voltammetry using In1-NC and In-NCX modified electrodes.

8. Use of the electrochemical sensor prepared by the preparation method according to claim 7, characterized in that: The electrochemical active area of ​​the In1-NC modified electrode is larger than 0.37 cm 2 .

9. Use of the electrochemical sensor prepared by the preparation method according to claim 7, characterized in that: The detection limit of the electrochemical sensor for dopamine is 0.279 μM.

10. Use of the electrochemical sensor prepared by the preparation method according to claim 7, characterized in that: The dopamine electrochemical response of the electrochemical sensor after 6 days was greater than 92%.

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