Use of an electrochemical sensor in the detection of metronidazole antibiotic

Abstract

The application develops an application of an electrochemical sensor in metronidazole antibiotic detection, the electrochemical sensor is that graphene oxide nanosheet is placed in a mixed solution of ultrapure water-ethanol, pH value is adjusted to 1-5, ultrasonic is obtained, and a protonated graphene oxide colloidal solution is obtained; platinum chlorate is put into the protonated graphene oxide colloidal solution, and [PtCl6] 2‑ -GO colloidal is prepared after ultrasonic at 2-5 DEG C; [PtCl6] 2‑ -GO colloidal is dropped on the surface of a pretreated electrode, then the electrode is dried, the electrode is placed in a PBS buffer solution after drying, and the electrochemical sensor is obtained by cyclic voltammetry scanning; the electrochemical sensor has high sensitivity, low detection limit and can selectively recognize metronidazole.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensor application technology, specifically relating to a method for preparing an electrochemical sensor and its application. Background Technology

[0002] Tinidazole is a synthetic drug containing a 5-nitroimidazole ring structure. Due to its highly effective antibacterial properties, it is widely used clinically to treat diseases caused by protozoa and anaerobic bacteria (such as periodontal disease, genitourinary disease, and soft tissue infections). Furthermore, in livestock farming, tinidazole is used as a food additive in fish and poultry feed to prevent animal infections. However, excessive use of tinidazole can have many adverse effects on humans, such as genotoxicity, seizures, mutagenicity, headaches, and carcinogenicity. Moreover, long-term use of tinidazole can lead to drug resistance, endangering human health. In particular, the large-scale use and inappropriate discharge of antibiotics into the environment in recent years have caused serious harm to ecosystems and humans. Therefore, rapid and accurate monitoring of tinidazole is crucial for limiting drug abuse and protecting human health.

[0003] Conventional methods for detecting tinidazole include spectrophotometry, liquid chromatography, gas chromatography, and fluorescence methods. However, these analytical techniques have limitations such as complex operation, high cost, and time consumption. Electrochemical analysis, with its excellent ability to determine electroactive substances, is considered a powerful analytical tool. Compared with conventional detection methods, electrochemical analysis methods have been widely used in recent years due to their advantages such as simple structure, fast response time, good selectivity, high sensitivity, and low cost. Summary of the Invention

[0004] This invention proposes a method for preparing an electrochemical sensor and its application in the detection of tinidazole antibiotics. The electrochemical sensor prepared by this invention can selectively identify tinidazole.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] 1. Place graphene oxide nanosheets in a mixture of ultrapure water and ethanol, adjust the pH to 1-5, and sonicate for 25-35 minutes to obtain a protonated graphene oxide colloidal solution.

[0007] The ultrapure water-ethanol mixture is prepared by mixing ultrapure water and anhydrous ethanol at a volume ratio of 0.1 to 10:1; the pH is adjusted using 2M HCl solution.

[0008] 2. Platinum chlorate was placed in a protonated graphene oxide colloidal solution and sonicated at 2-5°C for 3-4 hours to obtain [PtCl6]. 2- -GO colloid; [PtCl6] 2--GO colloid was dropped onto the surface of the pretreated electrode, and then the electrode was dried. After drying, the electrode was placed in 0.1 mol / L PBS buffer solution with pH=7. Cyclic voltammetry was used to scan at a scan rate of 50 mV / s, with a scan range of -0.2 to -1.7 V, for 10 cycles to obtain an electrochemical sensor (Pt-rGO / SPCE).

[0009] The mass ratio of chloroplatinic acid to graphene oxide nanosheets is 0.1%~20%; the pretreated electrode is prepared by ultrasonically cleaning a glassy carbon electrode or a screen-printed electrode in ultrapure water for 1~2 minutes; the drying temperature is 55~65℃.

[0010] 3. The electrochemical sensor prepared by the above method is applied to the electrochemical detection of tinidazole. Specifically, the electrochemical sensor is used as the working electrode. One end of the working electrode, the counter electrode, and the reference electrode are connected to an electrochemical workstation, and the other ends of the working electrode, the counter electrode, and the reference electrode are placed in an electrolyte containing 0-30 μmol / L tinidazole in an electrolytic cell. Electrochemical forward scanning is used for detection. The enrichment time is set to 10-30 seconds. The solution is stirred while enriching. After enrichment, stirring is stopped. After standing for 1-10 seconds, a forward scanning voltage with a voltage scanning range of -0.2V to -1.2V is applied to the three-electrode system. The current-voltage changes are recorded by the electrochemical workstation to obtain a current-voltage curve. The standard curve corresponding to tinidazole is plotted with the tinidazole concentration as the abscissa and the reduction peak current as the ordinate. The regression equation is obtained to determine the linear relationship between the tinidazole concentration and the peak current.

[0011] 4. Place the sample to be tested into an electrolytic cell and detect it using an electrochemical workstation as described above to obtain the peak current corresponding to tinidazole in the sample. Substitute the current into the regression equation to calculate the tinidazole content in the sample.

[0012] The electrolyte is a PBS buffer solution with a pH of 5-9 and a concentration of 0.1-1 mol / L.

[0013] Advantages and technical effects of this invention:

[0014] The electrochemical sensor prepared in this invention has the ability to electrochemically detect tinidazole antibiotic in aqueous solution. Results show that this electrochemical sensor has high sensitivity and a low detection limit. The excellent detection performance of this electrochemical sensor is attributed to the [PtCl6] proposed in this invention. 2- -GO colloidal materials; firstly, graphene oxide is [PtCl6]. 2-The invention provides ample adsorption sites, thereby reducing Pt aggregation during electrochemical reduction and improving Pt utilization and catalytic activity. Secondly, the in-situ generation of Pt nanoparticles not only provides excellent catalytic capabilities for subsequent electrochemical applications but also catalyzes the electrochemical reduction of GO, increasing the reduction rate of GO on the substrate electrode surface and enhancing the degree of reduction. Furthermore, the adsorption interaction between the electrode-modified colloid based on "metal ions" and "functionalized nanomaterials" proposed in this invention has the potential for application in electrochemical sensors. Attached Figure Description

[0015] Figure 1 SEM images of the electrochemical sensor;

[0016] Figure 2 The peak response current of tinidazole at different concentrations was detected by differential pulse voltammetry.

[0017] Figure 3 This is a standard curve of tinidazole concentration versus response current; Implementation

[0018] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the content described.

[0019] Example 1: Preparation method and application of tinidazole electrochemical sensor

[0020] (1) Place 3.75 mg of graphene oxide nanosheets in 15 mL of a mixture of ultrapure water and anhydrous ethanol (volume ratio 7:3), adjust the pH to 2 with 2 M HCl, and sonicate for 30 min to obtain a clear yellow protonated graphene oxide colloidal solution (0.25 mg / mL).

[0021] (2) Place 0.1181 mg of platinum chlorate in a protonated graphene oxide colloidal solution, maintain the temperature in the range of 2~5℃, and sonicate for 4 h to obtain [PtCl6]. 2- -GO colloid;

[0022] (3) Add 9 μL of [PtCl6] 2- -GO colloid was dropped onto the surface of a glassy carbon electrode (which was ultrasonically cleaned in ultrapure water for 2 min), and then the electrode was placed in a vacuum drying oven at 60°C for 10 min.

[0023] (4) After drying, the electrode was placed in 0.1M PBS buffer solution with pH=7, and cyclic voltammetry was used to scan at 50mV / s in the range of -0.2 to -1.6V for 10 cycles to obtain the electrochemical sensor. The SEM image of the electrochemical sensor is shown in [image missing]. Figure 1 ;

[0024] (5) Detection of tinidazole

[0025] a. Testing instruments and conditions

[0026] The testing instruments include an electrochemical workstation, an electrolytic cell, an electrochemical sensor prepared in step (4) as a working electrode, a counter electrode (platinum electrode), and a silver / silver chloride reference electrode;

[0027] b. Drawing the standard curve

[0028] Place 20 mL of 0.1 mol / L PBS buffer solution (pH=7) containing tinidazole (TNZ) at a concentration range of 0~30 μmol / L in the electrolytic cell;

[0029] On the electrochemical workstation, differential pulse voltammetry (DPV) was selected, and the enrichment time was set to 20 s. A magnetic stir bar was placed in the electrolytic cell, and the stirring speed of the electric stirrer was set to 300 rpm. After the enrichment time was completed, stirring of the solution in the electrolytic cell was immediately stopped. After standing for 3 s, a positive scanning voltage with a range of -0.55 V to -1 V was applied to the working electrode. The current-voltage changes were recorded by the electrochemical workstation to obtain the current-voltage curve (e.g., ...). Figure 2 (As shown); ③ Plot the standard curves for tinidazole (TNZ) with the concentration of tinidazole (TNZ) on the x-axis and the peak current value on the y-axis, and perform linear regression to obtain the linear relationship between the concentration of tinidazole (TNZ) and the peak current (as shown). Figure 3 (As shown); this linear relationship (standard curve) is used for quantitative detection of the concentration of tinidazole to be tested; the linear relationship between the tinidazole concentration and the peak current corresponding to this working electrode is as follows:

[0030] I TNZ = -2.495×C TNZ -15.468 (0.13~10μM, R2=0.996);

[0031] I TNZ = -1.489×C TNZ -26.09 (10~30μM, R) 2 =0.995);

[0032] c. Calculation of detection limit

[0033] The theoretical detection limit was determined to be 1.5 nM using the formula LOD = 3 SD / M (where SD = standard deviation of the blank signal and M = slope of the calibration plot).

[0034] d. Detection of the sample to be tested

[0035] The 0.1 mol / L PBS buffer solutions containing 5 and 15 μmol / L tinidazole were tested using the same experimental method as in step b. The measured peak currents were substituted into the linear equation in step b, and the tinidazole contents were calculated to be 4.87 and 15.12 μmol / L, respectively.

[0036] Example 2: Preparation method and application of tinidazole antibiotic electrochemical sensor

[0037] The preparation and application methods of the electrochemical sensor in this embodiment are the same as in Example 1, except that [PtCl6] is used. 2- -GO colloid was dropped onto the surface of a screen-printed electrode (ultrasonically cleaned in ultrapure water for 2 min); the electrode was used to detect 0.1 mol / L PBS buffer solutions containing 5 and 15 μmol / L tinidazole, and the results showed that the tinidazole content was 5.12 and 15.23 μmol / L, respectively.

[0038] Example 3: Preparation method and application of tinidazole antibiotic electrochemical sensor

[0039] (1) 3.75 mg of graphene oxide nanosheets were placed in a mixture of 15 mL of ultrapure water and ethanol (volume ratio 4:1), the pH of the GO solution was adjusted to 3 with 2 M HCl, and the solution was sonicated for 35 min to obtain a clear yellow protonated graphene oxide colloidal solution.

[0040] (2) Place 0.187 mg of platinum chlorate in a protonated graphene oxide colloidal solution and sonicate for 3 h at 2-5 °C to obtain [PtCl6]. 2- -GO colloid;

[0041] (3) Add 7 μL of [PtCl6] 2- -GO colloid was dropped onto the surface of a glassy carbon electrode (which was ultrasonically cleaned in ultrapure water for 1 min), and then the electrode was placed in a vacuum drying oven at 65°C for 10 min.

[0042] (4) After drying, the electrode was placed in 0.1M PBS buffer solution with pH=7 and cyclic voltammetry was used to scan at 50mV / s in the range of -0.2 to -1.6V for 10 cycles to obtain an electrochemical sensor.

[0043] (5) The detection process for tinidazole is the same as in Example 1.

[0044] The concentrations of tinidazole in 0.1 mol / L PBS buffer solutions containing 5 and 15 μmol / L were detected using the same experimental method as in step b. The measured peak currents were substituted into the linear equations to calculate the tinidazole concentrations as 4.984 and 15.13 μmol / L, respectively.

Claims

1. Application of an electrochemical sensor in the detection of tinidazole antibiotic; The electrochemical sensor is prepared by placing graphene oxide nanosheets in a mixture of ultrapure water and ethanol, adjusting the pH to 1-5, and sonicating for 25-35 minutes to obtain a protonated graphene oxide colloidal solution; then, platinum chlorate is added to the protonated graphene oxide colloidal solution and sonicated at 2-5°C for 3-4 hours to obtain [PtCl6]. 2- -GO colloid; [PtCl6] 2- -GO colloid was dropped onto the surface of the pretreated electrode, and then the electrode was dried. After drying, the electrode was placed in 0.1 mol / L PBS buffer solution with pH=7. Cyclic voltammetry was used to scan the electrode at a scan rate of 50 mV / s, with a scan range of -0.2 to -1.7 V, for 10 cycles to obtain the electrochemical sensor.

2. The application according to claim 1, characterized in that: The ultrapure water-ethanol mixture is prepared by mixing ultrapure water and anhydrous ethanol in a volume ratio of 0.1 to 10:

1.

3. The application according to claim 1, characterized in that: The mass ratio of chloroplatinic acid to graphene oxide nanosheets is 0.1% to 20%.

4. The application according to claim 1, characterized in that: The pretreated electrode is prepared by ultrasonically cleaning a glassy carbon electrode or a screen-printed electrode in ultrapure water for 1-2 minutes.

5. The application according to claim 1, characterized in that: An electrochemical sensor was used as the working electrode. One end of the working electrode, counter electrode, and reference electrode were connected to an electrochemical workstation, and the other ends of the working electrode, counter electrode, and reference electrode were placed in an electrolyte containing 0-30 μmol / L tinidazole in an electrolytic cell. Detection was performed using an electrochemical forward scan method with an enrichment time of 10-30 seconds. The solution was stirred during enrichment, and stirring was stopped after enrichment. After a settling period of 1-10 seconds, a forward scan voltage with a range of -0.2V to -1.2V was applied to the three-electrode system. The electrochemical workstation recorded the current-voltage changes, obtaining a current-voltage curve. A standard curve for tinidazole was plotted with tinidazole concentration on the x-axis and reduction peak current on the y-axis to obtain a regression equation and determine the linear relationship between tinidazole concentration and peak current. The sample to be tested was placed in the electrolytic cell and detected by the electrochemical workstation using the same method. The peak current corresponding to tinidazole in the sample was obtained, and the tinidazole content in the sample was calculated by substituting it into the regression equation.

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