A novel electrochemical detection method for dopamine

Abstract

This invention belongs to the field of electrochemistry, specifically relating to a novel electrochemical detection method for dopamine. The novel dopamine electrochemical detection method of this invention uses a trimethylaminoethylperyleneimide-functionalized molybdenum disulfide nanoflower composite material as the electrochemical material; potassium persulfate is used as a signal enhancer to detect dopamine; and the current reduction value of peryleneimide is used as the detection signal. The current reduction value of this material exhibits a good linear response to dopamine in the range of 10 pM–100 μM.

Description

Technical Field

[0001] This invention belongs to the field of electrochemistry, specifically relating to a novel electrochemical detection method for dopamine. Background Technology

[0002] Electrochemical technology is widely used in the field of biosensors due to its high sensitivity, low background interference, fast response, and low cost. The dopamine electrochemical sensor currently being constructed utilizes the direct electrochemical oxidation of dopamine molecules at the electrode as its detection mechanism. The detection signal originates from the electrochemical oxidation current of dopamine.

[0003] Currently constructed electrochemical sensors for dopamine suffer from low sensitivity and a high lower limit of linear detection range, often at micromolar concentrations, which is far greater than the dopamine concentration in human physiological fluids (urine 0.387-1.548 μM, blood <130 pM). Furthermore, the preparation process of the electrochemical materials used is complex and costly. Summary of the Invention

[0004] The purpose of this invention is to provide a novel electrochemical detection method for dopamine. This method has simple electrochemical material preparation, an increased linear detection range, and a lower detection limit, solving the problems of cumbersome preparation, high cost, and low sensitivity of electrochemical materials.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows:

[0006] The novel electrochemical detection method for dopamine described in this invention uses a trimethylamine ethyl peryleneimide-functionalized molybdenum disulfide nanoflower composite material as the electrochemical material.

[0007] Dopamine detection using potassium persulfate as a signal enhancer;

[0008] The decrease in current of perylene imide is used as the detection signal.

[0009] Preferably, the preparation steps of the trimethylamine ethyl peryleneimide-functionalized molybdenum disulfide nanoflower composite material include:

[0010] S1: Synthesis of N,N'-bis(2-dimethylaminoethyl)peryleneimide

[0011] S2: Synthesis of N,N'-bis(2-trimethylaminoethyl)peryleneimide

[0012] S3: Preparation of MoS2 nanoflowers

[0013] S4: Preparation of N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material.

[0014] Preferably, the synthetic steps of N,N'-bis(2-dimethylaminoethyl)peryleneimide are as follows:

[0015] Perylenetetraanic anhydride and 2-dimethylaminoethylamine were placed in an isobutanol solution and heated and stirred under a nitrogen atmosphere. The crude product was filtered and washed with ultrapure water and ethanol. The obtained product was used to remove unreacted perylenetetraanic anhydride with sodium hydroxide solution. The product was then filtered, washed with ultrapure water and ethanol, and dried under vacuum to obtain N,N'-bis(2-dimethylaminoethyl)peryleneimide.

[0016] Preferably, the synthetic steps of N,N'-bis(2-trimethylaminoethyl)peryleneimide are as follows:

[0017] N,N'-bis(2-dimethylaminoethyl)peryleneimide was refluxed with iodomethane in toluene. The product was filtered, washed with diethyl ether, and dried under vacuum to obtain N,N'-bis(2-trimethylaminoethyl)peryleneimide. Perylene tetrahydric anhydride and 2-dimethylaminoethylamine were placed in isobutanol solution and heated and stirred under a nitrogen atmosphere. The crude product was filtered and washed with ultrapure water and ethanol. The obtained product was treated with sodium hydroxide solution to remove unreacted perylene tetrahydric anhydride. The resulting product was filtered, washed with ultrapure water and ethanol, and dried under vacuum.

[0018] Preferably, the synthetic steps of N,N'-bis(2-trimethylaminoethyl)peryleneimide are as follows:

[0019] N,N'-bis(2-dimethylaminoethyl)peryleneimide was refluxed with iodomethane in toluene, the product was filtered, washed with diethyl ether, and dried under vacuum to obtain N,N'-bis(2-trimethylaminoethyl)peryleneimide.

[0020] Preferably, the preparation steps of MoS2 nanoflowers are as follows: ammonium molybdate and thiourea are placed in ultrapure water and stirred to dissolve at room temperature. Hydroxylamine hydrochloride is added, heated, kept warm, cooled to room temperature, centrifuged, washed with ultrapure water and ethanol, and the product is vacuum dried. The powder is then dissolved in ultrapure water and sonicated to obtain a uniformly dispersed MoS2 nanoflower solution.

[0021] Preferably, the preparation steps of N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material are as follows: mix N,N'-bis(2-trimethylaminoethyl)peryleneimide aqueous solution and MoS2 nanoflower solution, stir, filter, remove unbound N,N'-bis(2-trimethylaminoethyl)peryleneimide molecules, finally vacuum dry the product, dissolve it in ultrapure water, and store it at 4°C.

[0022] Preferably, the detection steps are as follows:

[0023] The glassy carbon electrode was polished with aluminum powder and ultrasonically cleaned with ultrapure water and ethanol. The electrode surface was dried with nitrogen gas. Then, a solution of N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material was dropped onto the surface of the glassy carbon electrode and dried at room temperature. Dopamine solutions of different concentrations were added to a phosphate buffer solution containing K2S2O8. The glassy carbon electrode modified with N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material was immersed in the above solution for DPV testing.

[0024] The present invention has the following beneficial effects:

[0025] This technical solution utilizes perylene imide molecules as an electrochemical probe and potassium persulfate as a signal enhancer to detect dopamine. The reduction current of perylene imide molecules is significantly enhanced under the cyclic oxidation of potassium persulfate. In the presence of dopamine, potassium persulfate oxidizes dopamine to dopaquinone, which is then electrochemically reduced back to dopamine, initiating a chemical oxidation-electrochemical reduction cycle. During this cycle, dopamine continuously consumes K₂S₂O₈, and the oxidized dopaquinone continuously polymerizes into black, sticky polydopamine. Polydopamine readily adsorbs onto the electrode surface, hindering electron transfer. The competitive consumption of potassium persulfate by dopamine and the blocking effect of polydopamine on electron transfer jointly reduce the reduction current of perylene imide molecules. Based on the above detection mechanism, to enhance stability and sensitivity, this technical solution utilizes molybdenum disulfide nanoflowers to load positively charged trimethylaminoethyl perylene imide as an electrochemical material, using potassium persulfate as a signal enhancer to detect dopamine. The current reduction value of perylene imide was used as the detection signal. The current reduction value of this material showed a good linear response to dopamine in the range of 10 pM to 100 μM. Attached Figure Description

[0026] Figure 1 This is the proton NMR spectrum of N,N'-bis(2-dimethylaminoethyl)peryleneimide;

[0027] Figure 2 This is the proton NMR spectrum of N,N'-bis(2-trimethylaminoethyl)peryleneimide;

[0028] Figure 3 This is a transmission electron microscope image of MoS2 nanoflowers;

[0029] Figure 4 The differential pulse voltammetry curves (A) of the MoS2 / TMPDI-modified glassy carbon electrode in 0.1M phosphate buffer solutions containing different concentrations of dopamine and 50mM K2S2O8 are shown, where the dopamine concentration ranges from 10pM to 100μM. The current change of the MoS2 / TMPDI-modified glassy carbon electrode is related to lgC. DA The linear relationship. Detailed Implementation

[0030] The present invention will be further explained below with reference to the embodiments, but these should not be construed as limiting the present invention.

[0031] Example 1

[0032] The steps of the electrochemical detection method for dopamine described in this invention are as follows:

[0033] Synthesis of S1.N,N'-bis(2-dimethylaminoethyl)peryleneimide.

[0034] 0.98 g of perylenetetracarboxylic anhydride and 0.55 g of 2-dimethylaminoethylamine were placed in 50 mL of isobutanol solution and heated and stirred at 90 °C for 24 h under a nitrogen atmosphere. The crude product was filtered and washed with ultrapure water and ethanol. The obtained product was heated at 90 °C for half an hour with 35 mL of 5% sodium hydroxide solution to remove unreacted perylenetetracarboxylic anhydride. The obtained product was filtered, washed with ultrapure water and ethanol, and dried under vacuum to obtain N,N'-bis(2-dimethylaminoethyl)peryleneimide. The NMR was analyzed by 1H NMR spectroscopy (400 MHz, 25 °C) in deuterated trifluoroacetic acid solvent. Figure 1 The singlet at 3.67-3.73 ppm is due to 12 H atoms on the methyl group at position 1; the multiplet at 4.21-4.28 ppm is due to 4 H atoms on the methylene group at position 2; the multiplet at 5.24-3.42 ppm is due to 4 H atoms on the methylene group at position 3; and the quartet at 9.22-9.35 ppm is due to 8 H atoms on the benzene ring at positions 4 and 5.

[0035] Synthesis of S2.N,N'-bis(2-trimethylaminoethyl)peryleneimide (TMPDI).

[0036] 0.30 g of N,N'-bis(2-dimethylaminoethyl)peryleneimide was refluxed with 0.15 mL of iodomethane in 10 mL of toluene for 3 hours. The product was filtered, washed with diethyl ether, and dried under vacuum to obtain N,N'-bis(2-trimethylaminoethyl)peryleneimide (TMPDI). The product was analyzed by 1H NMR spectroscopy (400 MHz, 25 °C) in deuterated trifluoroacetic acid solvent. Figure 2 The singlet at 3.38-3.99 ppm represents 18 H atoms on the methyl group at position 1; the singlet at 4.03-4.52 ppm represents 4 H atoms on the methylene group at position 3; the singlet at 4.87-5.40 ppm represents 4 H atoms on the methylene group at position 2; and the doublet at 7.56-8.87 ppm represents 8 H atoms on the benzene ring at positions 4 and 5.

[0037] Preparation of S3.MoS2 nanoflowers

[0038] 0.47 g ammonium molybdate and 0.59 g thiourea were dissolved in 60 mL of ultrapure water by stirring at room temperature. 0.517 g hydroxylamine hydrochloride was added to the solution, which was then transferred to a 100 mL hydrothermal reactor and gradually heated to 200 °C. This temperature was maintained for 36 h. After cooling to room temperature, the black suspension was centrifuged at 4500 r / min and washed with ultrapure water and ethanol. The product was then vacuum dried. 15 mg of MoS2 powder was dissolved in 20 mL of ultrapure water and sonicated for 1 h to obtain a uniformly dispersed MoS2 nanoflower solution. The transmission electron microscopy (TEM) images of the MoS2 nanoflowers are shown below. Figure 3 .

[0039] Preparation of S4.N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composites

[0040] 20 mL of N,N'-bis(2-trimethylaminoethyl)peryleneimide aqueous solution (200 μM) and 10 mL of the above MoS2 nanoflower solution were added to a 50 mL round-bottom flask and stirred at room temperature for 3 h. The product was then filtered through a 0.22 μm nylon membrane to remove unbound N,N'-bis(2-trimethylaminoethyl)peryleneimide molecules. Finally, the product was vacuum dried to obtain N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material, which was dissolved in 5 mL of ultrapure water and stored at 4 °C.

[0041] S5. Electrochemical detection of dopamine

[0042] First, the glassy carbon electrode was polished with 0.3 μm and 0.05 μm aluminum powder, respectively, and then ultrasonically cleaned with ultrapure water and ethanol. Finally, the electrode surface was dried with nitrogen gas. Then, 6 μL of the N,N'-bis(2-trimethylaminoethyl)peryleneimide-functionalized MoS2 nanoflower composite material solution obtained in step S4 was dropped onto the surface of the glassy carbon electrode and dried at room temperature. 400 μL of dopamine solutions of different concentrations were added to a phosphate buffer solution containing K2S2O8. The MoS2 / TMPDI-modified glassy carbon electrode was immersed in the above solution for DPV testing. The test results are as follows. Figure 4 As dopamine concentration increases, the reduction current of TMPDI gradually decreases. Figure 4 A). Furthermore, the decrease in reduction current of TMPDI showed a good linear response to dopamine in the range of 10 pM to 100 μM. Figure 4 B) The detection limit is 4.1 pM. Compared with traditional electrochemical sensors based on the direct electrochemical oxidation mechanism of dopamine, this sensing method has a wider linear detection range, a lower detection limit, a simpler material preparation method, and lower cost.

[0043] This technical solution utilizes perylene imide molecules as an electrochemical probe and potassium persulfate as a signal enhancer to detect dopamine. The reduction current of perylene imide molecules is significantly enhanced under the cyclic oxidation of potassium persulfate. In the presence of dopamine, potassium persulfate oxidizes dopamine to dopaquinone, which is then electrochemically reduced back to dopamine, initiating a chemical oxidation-electrochemical reduction cycle. During this cycle, dopamine continuously consumes K₂S₂O₈, and the oxidized dopaquinone continuously polymerizes into black, sticky polydopamine. Polydopamine readily adsorbs onto the electrode surface, hindering electron transfer. The competitive consumption of potassium persulfate by dopamine and the blocking effect of polydopamine on electron transfer jointly reduce the reduction current of perylene imide molecules. Based on the above detection mechanism, to enhance stability and sensitivity, this technical solution utilizes molybdenum disulfide nanoflowers to load positively charged trimethylaminoethyl perylene imide as an electrochemical material, using potassium persulfate as a signal enhancer to detect dopamine. The current reduction value of perylene imide was used as the detection signal. The material exhibited a good linear response to dopamine in the range of 10 pM to 100 μM.

Claims

1. A method for electrochemical detection of dopamine, characterized in that, N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite is used as an electrochemical material; Potassium persulfate is used as a signal enhancer to detect dopamine; The current reduction value of N,N'-bis (2-trimethylamine ethyl) perylene imide is used as a detection signal; The preparation steps of N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite include: S1: synthesis of N,N'-bis (2-dimethylamine ethyl) perylene imide, S2: synthesis of N,N'-bis (2-trimethylamine ethyl) perylene imide, S3: preparation of MoS2 nanoflower, S4: preparation of N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite; The synthesis steps of N,N'-bis (2-dimethylamine ethyl) perylene imide are as follows: Perylene tetracarboxylic anhydride and 2-dimethylamine ethyl amine are placed in isobutyl alcohol solution, heated and stirred under nitrogen atmosphere, the crude product is filtered and washed with ultrapure water and ethanol, the obtained product is treated with sodium hydroxide solution to remove unreacted perylene tetracarboxylic anhydride, the obtained product is filtered, washed with ultrapure water and ethanol, and then vacuum dried to obtain N,N'-bis (2-dimethylamine ethyl) perylene imide; The synthesis steps of N,N'-bis (2-trimethylamine ethyl) perylene imide are as follows: N,N'-bis (2-dimethylamine ethyl) perylene imide and iodomethane are refluxed in toluene, the product is filtered and rinsed with diethyl ether, and then vacuum dried to obtain N,N'-bis (2-trimethylamine ethyl) perylene imide. 2.The method for electrochemical detection of dopamine according to claim 1, characterized in that, The preparation steps of N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite are as follows: N,N'-bis (2-trimethylamine ethyl) perylene imide aqueous solution and MoS2 nanoflower solution are mixed, stirred, filtered, and unbound N,N'-bis (2-trimethylamine ethyl) perylene imide molecules are removed, and finally the product is vacuum dried and dissolved in ultrapure water and stored at 4℃. 3.The method for electrochemical detection of dopamine according to claim 1, characterized in that, The preparation steps of MoS2 nanoflower are as follows: ammonium molybdate and thiourea are placed in ultrapure water and dissolved by stirring at room temperature, hydroxylamine hydrochloride is added, heated and incubated, cooled to room temperature, centrifuged, washed with ultrapure water and ethanol, and the product is vacuum dried, the powder is dissolved in ultrapure water, and ultrasonic treatment is performed to obtain a uniformly dispersed MoS2 nanoflower solution.

4. The method of electrochemical detection of dopamine according to claim 1, wherein, The detection steps are as follows: The glassy carbon electrode is polished with aluminum powder and ultrasonically cleaned with ultrapure water and ethanol, the surface of the electrode is dried with nitrogen, then N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite solution is dropped onto the surface of the glassy carbon electrode, dried at room temperature, different concentrations of dopamine solution are added to K2S2O8-containing phosphate buffer solution, and the N,N'-bis (2-trimethylamine ethyl) perylene imide functionalized MoS2 nanoflower composite modified glassy carbon electrode is immersed in the above solution for DPV test.

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