A preparation method of uric acid bioelectrochemical sensor based on MOF material

Abstract

The invention discloses a preparation method of a uric acid bioelectrochemical sensor based on a MOF material, belonging to the technical field of electrochemical biosensors. The method of the invention comprises the following steps: mixing terephthalic acid and chromium nitrate, adding hydrofluoric acid, reacting for 20-24 hours, centrifuging to obtain a dark green precipitate, vacuum drying at 80°C for 8-10 hours, and naturally cooling to obtain the MOF material MIL-101(Cr). The uric acid bioelectrochemical sensor prepared using the MOF material MIL-101(Cr) as a catalyst has excellent performance, good linear correlation fit within the concentration range of 25μM-0.1mM, a low detection limit, the ability to detect low-concentration uric acid, and good stability and reproducibility.

Description

Technical Field

[0001] The present invention relates to a method for preparing a uric acid bioelectrochemical sensor based on MOF materials, belonging to the technical field of bioelectrochemistry. Background Art

[0002] Uric acid (UA) is one of the major metabolic products in the human body. Abnormal UA levels can lead to a range of symptoms, including hyperuricemia, uric acid nephropathy, and gout, seriously impairing health. Therefore, it is necessary to develop effective analytical techniques to accurately measure UA concentration and monitor its real-time activity. Uric acid concentration is typically measured using fluorescence, liquid chromatography, and UV-visible spectroscopy. However, these methods suffer from complex procedures, time-consuming processes, high costs, and limited accuracy, limiting their practical applications. Electrochemical sensors, due to their high efficiency and accuracy, are considered an emerging and promising detection method. The use of enzymes as catalysts in bioelectrochemical sensors has seen rapid development. However, the further development of enzymes is hampered by drawbacks such as poor stability, high environmental requirements, and susceptibility to protein disruption.

[0003] In this experiment, the MOF material MIL-101(Cr) was prepared by hydrothermal method to replace the biological enzyme as the catalyst. It can not only make up for a series of problems of the biological enzyme catalyst, but also the obtained bioelectrochemical sensor has good responsiveness, low detection limit, and good stability and reproducibility. Summary of the Invention

[0004] The present invention aims to provide a method for preparing a uric acid bioelectrochemical sensor based on MOF materials. The method has a simple process and is quick and convenient to operate. The modified electrode prepared with MIL-101(Cr) can be used to quickly detect the concentration of uric acid in a solution. The method specifically comprises the following steps:

[0005] (1) Terephthalic acid and chromium nitrate are mixed in a molar ratio of 1:1 to 1:1.5, ground evenly, added with deionized water, and stirred magnetically.

[0006] (2) Add hydrofluoric acid to the mixed solution in step (1) at a molar ratio of chromium nitrate to hydrofluoric acid of 1:1 to 1:2, then continue magnetic stirring, and finally ultrasonicate.

[0007] (3) The mixed solution in step (2) was transferred into a polytetrafluoroethylene liner. After the hydrothermal reaction was completed, the mixture was cooled to room temperature and centrifuged to obtain a dark green precipitate.

[0008] (4) The precipitate in step (3) was further purified by repeatedly washing with hot alcohol, N,N-dimethylformamide (DMF), and deionized water for 3 to 4 times (washing with three solutions respectively, in no particular order), and finally vacuum drying to obtain the MOF material MIL-101(Cr).

[0009] (5) MIL-101(Cr) and ethanol were mixed by ultrasonic treatment in a mass ratio of 2:1 to 1:1, and the mixed solution was vertically dropped onto the surface of the pretreated glassy carbon electrode. After drying, Nafion solution was added dropwise, and the modified electrode MIL-101(Cr) / GCE was obtained after drying.

[0010] (6) A three-electrode system was formed by combining the MIL-101(Cr) / GCE modified electrode, the Ag / AgCl electrode, and the Pt counter electrode to obtain a bioelectrochemical sensor.

[0011] Preferably, the magnetic stirring time in step (1) of the present invention is 30 to 45 minutes; and the concentration of chromium nitrate is 0.06 g / ml to 0.08 g / ml.

[0012] Preferably, the magnetic stirring time in step (2) of the present invention is 20 to 30 minutes, and the ultrasonic treatment time is 10 to 30 minutes.

[0013] Preferably, the hydrothermal reaction time in step (3) of the present invention is 20-24 h, and the temperature is 220°C.

[0014] Preferably, in step (4) of the present invention, the temperature of the hot alcohol is 50°C to 60°C; the vacuum drying temperature is 60°C to 80°C; and the vacuum drying time is 8 to 10 hours.

[0015] Preferably, the volume of the mixed solution pipetted in step (5) of the present invention is 6 to 10 μL; and the volume ratio of the mixed solution to the Nafion solution is 1:1 to 2:1.

[0016] The electrochemical behavior test of the uric acid bioelectrochemical sensor prepared by the method of the present invention was carried out: the modified electrode MIL-101(Cr) / GCE was used as the working electrode, the Ag / AgCl electrode was used as the reference electrode, and the Pt electrode was used as the counter electrode. Uric acid was dissolved in phosphate buffer solution (PBS) to obtain different concentrations of uric acid, and the differential pulse voltammetry (DPV) curves at different concentrations were measured using a three-electrode system.

[0017] Beneficial effects of the present invention:

[0018] (1) The uric acid bioelectrochemical sensor prepared by the present invention can provide a rapid and efficient detection method for uric acid solutions of unknown solubility, with a low detection limit, high linear fit, good stability and reproducibility, and can detect low-concentration uric acid.

[0019] (2) The MIL-101(Cr) described in the present invention has a porous structure, which provides abundant reaction sites for the redox reaction of uric acid and catalyzes the oxidation of uric acid, thus overcoming the shortcomings of biological enzymes that are difficult to preserve and have poor environmental tolerance.

[0020] (3) The preparation process of the present invention is easy to control and simple to operate. The experimental operation process only requires the help of an electrochemical workstation and does not require other large-scale equipment, which is convenient and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 DPV curves of the bioelectrochemical sensor prepared with the modified electrode MIL-101(Cr) / GCE obtained in Example 1 of the present invention at different uric acid concentrations, a is the DPV curve for uric acid concentrations of 25 μM to 250 μM; b is the DPV curve for uric acid concentrations of 0.6 mM to 1 mM.

[0022] Figure 2 The bioelectrochemical sensor prepared with the modified electrode MIL-101(Cr) / GCE obtained in Example 1 of the present invention shows the fitting curves of the DPV curve oxidation peak current and different concentrations at different uric acid concentrations. a is the fitting curve of the uric acid concentration of 25 μM~250 μM and the corresponding DPV curve peak current; b is the fitting curve of the uric acid concentration of 0.6 mM~1 mM and the corresponding DPV curve peak current. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0024] Example 1

[0025] A method for preparing a uric acid bioelectrochemical sensor based on MOF material specifically comprises the following steps:

[0026] (1) Mix and grind 0.012 mol (4.8 g) of chromium nitrate and 0.012 mol (1.992 g) of terephthalic acid (the molar ratio of terephthalic acid to chromium nitrate is 1:1), add 60 mL of deionized water (the mass concentration of chromium nitrate is 0.08 g / ml), and stir magnetically for 30 min.

[0027] (2) Add 0.012 mol (0.2 mL) of hydrofluoric acid to the mixture in step (1) (the molar ratio of chromium nitrate to hydrofluoric acid is 1:1), then continue stirring for 30 min, and finally ultrasonicate for 10 min.

[0028] (3) The mixed solution in step (2) was transferred into a polytetrafluoroethylene liner, subjected to hydrothermal reaction at 220°C for 20 h, cooled to room temperature, and centrifuged to obtain a dark green precipitate.

[0029] (4) The precipitate in step (3) was further purified by washing it three times with 50°C hot alcohol, N,N-dimethylformamide (DMF), and deionized water, and finally vacuum dried at 60°C for 8h to obtain the MOF material MIL-101(Cr).

[0030] (5) Disperse 0.1 g of MIL-101(Cr) powder in 0.1 mL of ethanol solution and mix ultrasonically. Pipette 6 μL of the mixture and drop it vertically on the surface of the pretreated glassy carbon electrode. After drying, add 6 μL of Nafion solution. After drying, the modified electrode MIL-101(Cr) / GCE is obtained.

[0031] The MIL-101(Cr) / GCE modified electrode obtained in this example, the Ag / AgCl electrode, and the Pt counter electrode constitute a three-electrode system. Differential pulse voltammetry was performed in uric acid solutions with different concentrations (25 μL to 1 mM). The DPV curves are shown in Figure 2. Figure 1 The DPV curve oxidation peak current was linearly fitted with different uric acid concentrations, as shown in Figure 2 As shown in the figure, this uric acid bioelectrochemical sensor has a good linear relationship in the uric acid concentration range of 25μmol / L~1mM, and the detection limit is 5.53μmol / L (S / N=3). It can be seen that the uric acid bioelectrochemical sensor prepared based on MOF material (MIL-101(Cr)) has a low detection limit and high sensitivity.

[0032] Example 2

[0033] A method for preparing a uric acid bioelectrochemical sensor based on MOF material specifically comprises the following steps:

[0034] (1) Mix and grind 0.006 mol (2.4 g) of chromium nitrate and 0.004 mol (0.664 g) of terephthalic acid (the molar ratio of terephthalic acid to chromium nitrate is 1:1.5), add 40 mL of deionized water (chromium nitrate mass concentration is 0.06 g / ml), and stir magnetically for 40 min.

[0035] (2) Add 0.006 mol (0.1 mL) of hydrofluoric acid to the mixture in step (1) (the molar ratio of chromium nitrate to hydrofluoric acid is 1:1), then continue stirring for 25 min, and finally ultrasonicate for 30 min.

[0036] (3) The mixed solution in step (2) was transferred into a polytetrafluoroethylene liner, subjected to hydrothermal reaction at 220°C for 22 h, cooled to room temperature, and centrifuged to obtain a dark green precipitate.

[0037] (4) The precipitate in step (3) was further purified by washing it four times with 50°C hot alcohol, N,N-dimethylformamide (DMF), and deionized water, and finally vacuum dried at 70°C for 9h to obtain the MOF material MIL-101(Cr).

[0038] (5) Disperse 0.5 g of MIL-101(Cr) powder in 0.32 mL of ethanol solution and mix ultrasonically. Pipette 10 μL of the mixture and drop it vertically on the surface of the pretreated glassy carbon electrode. After drying, add 10 μL of Nafion solution. After drying, the modified electrode MIL-101(Cr) / GCE is obtained.

[0039] Example 3

[0040] A method for preparing a uric acid bioelectrochemical sensor based on MOF material specifically comprises the following steps:

[0041] (1) Mix and grind 0.004 mol (1.6 g) of chromium nitrate and 0.004 mol (0.664 g) of terephthalic acid (the molar ratio of terephthalic acid to chromium nitrate is 1:1), add 20 mL of deionized water (the mass concentration of chromium nitrate is 0.08 g / ml), and stir magnetically for 45 min.

[0042] (2) Add 0.004 mol (0.07 mL) of hydrofluoric acid to the mixture in step (1) (the molar ratio of chromium nitrate to hydrofluoric acid is 1:1), then continue stirring for 20 minutes, and finally ultrasonicate for 10 minutes.

[0043] (3) The mixed solution in step (2) was transferred into a polytetrafluoroethylene liner, subjected to hydrothermal reaction at 220°C for 24 h, cooled to room temperature, and centrifuged to obtain a dark green precipitate.

[0044] (4) The precipitate in step (3) was further purified by repeated washing with 50°C hot alcohol, N,N-dimethylformamide (DMF), and deionized water for 4 times, and finally vacuum dried at 80°C for 10 h to obtain the MOF material MIL-101(Cr).

[0045] (5) Disperse 0.2 g of MIL-101(Cr) powder in 0.25 mL of ethanol solution and mix ultrasonically. Pipette 10 μL of the mixture and drop it vertically on the surface of the pretreated glassy carbon electrode. After drying, add 5 μL of Nafion solution. After drying, the modified electrode MIL-101(Cr) / GCE is obtained.

[0046] The modified electrodes obtained in Examples 2 and 3 were used to prepare a uric acid bioelectrochemical sensor for uric acid detection, with performance similar to that of Example 1. This uric acid bioelectrochemical sensor exhibited good linearity over the uric acid concentration range of 25 μmol / L to 0.1 mM. This indicates that the uric acid bioelectrochemical sensor based on the MOF material (MIL-101(Cr)) exhibits excellent electrochemical sensing performance, with a low detection limit, high sensitivity, and good stability and reproducibility.

Claims

1. A method for preparing a uric acid bioelectrochemical sensor based on MOF materials, characterized in that: The specific steps include: (1) Mix terephthalic acid and chromium nitrate in a molar ratio of 1:1 to 1:1.5, grind them evenly, add deionized water, and stir magnetically; (2) adding hydrofluoric acid to the mixture of step (1) in a molar ratio of chromium nitrate to hydrofluoric acid of 1:1 to 1:2, then continuing magnetic stirring, and finally ultrasonicating; (3) The mixed solution in step (2) was transferred into a polytetrafluoroethylene liner, cooled to room temperature after the hydrothermal reaction was completed, and centrifuged to obtain a dark green precipitate; (4) The precipitate in step (3) was further purified by repeated washing with hot alcohol, N,N-dimethylformamide, and deionized water for 3 to 4 times, and finally vacuum dried to obtain the MOF material MIL-101(Cr); (5) Mix MIL-101(Cr) and ethanol in a mass ratio of 2:1 to 1:1 by ultrasonication, and vertically drop the mixture onto the surface of the pretreated glassy carbon electrode. After drying, add Nafion solution, and dry to obtain the modified electrode MIL-101(Cr) / GCE. (6) A three-electrode system consisting of a MIL-101(Cr) / GCE modified electrode, an Ag / AgCl electrode, and a Pt counter electrode was constructed to obtain a bioelectrochemical sensor; In step (1), the magnetic stirring time is 30 to 45 minutes, and the concentration of chromium nitrate is 0.06 g / ml to 0.08 g / ml; The hydrothermal reaction time in step (3) is 20-24 h, and the temperature is 220°C; In step (5), the volume of the mixed solution pipetted is 6 to 10 μL; the volume ratio of the mixed solution to the Nafion solution is 1:1 to 2:

1.

2. The method for preparing a uric acid bioelectrochemical sensor based on MOF material according to claim 1, characterized in that: In step (2), the magnetic stirring time is 20 to 30 minutes, and the ultrasonic treatment time is 10 to 30 minutes.

3. The method for preparing a uric acid bioelectrochemical sensor based on MOF material according to claim 1, characterized in that: In step (4), the temperature of the hot alcohol is 50°C to 60°C; the vacuum drying temperature is 60°C to 80°C, and the vacuum drying time is 8 to 10 hours.

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