Preparation method of electrochemical sensor and application of electrochemical sensor in detection of quinolone antibiotics

Abstract

The invention discloses a preparation method of an electrochemical sensor, which comprises the following steps: dispersing a conductive carrier in a sodium hydroxide solution, carrying out ultrasonic treatment at 30-80 DEG C for 0.5-4 hours, carrying out solid-liquid separation, washing the solid with deionized water, drying, suspending in the deionized water to obtain a dispersion liquid with the concentration of 1-10 mg / mL, adding silver nitrate into the dispersion liquid until the final concentration is 0.001-0.02 mg / mL, and carrying out ultrasonic treatment at 30-80 DEG C for 0.5-4 hours to obtain the electrochemical sensor. The preparation method comprises the following steps: performing ultrasonic dispersion for 0.5-3 hours, adding an excessive reducing agent, performing ultrasonic reduction for 2-5 hours at 30-80 DEG C, performing solid-liquid separation, washing a solid with deionized water, drying, dispersing a dried substance into an ethanol water solution, performing ultrasonic treatment for 0.5 hour, and dispensing a suspension onto a working electrode, thereby obtaining the electrochemical sensor. The sensor can realize recognition and accurate detection of quinolone antibiotics in a water body, and has the advantages of high sensitivity, wide linear range, low detection line and the like. And the material is simple in preparation method and easy for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical sensor application, and particularly relates to a preparation method of an electrochemical sensor and the application of the electrochemical sensor in detecting quinolone antibiotics. Background Art

[0002] Since the advent of antibiotics as revolutionary drugs, they have become an important tool for treating various infectious diseases in humans and livestock. Among them, quinolone antibiotics have become an important drug for treating infectious diseases due to their broad antibacterial spectrum, significant efficacy, relatively low side effects and good bioavailability. However, the widespread use of antibiotics is accompanied by the risk of environmental pollution. Antibiotics enter water bodies and soil through various pathways, such as discharge from urban sewage treatment plants and leachate from landfills, leading to water pollution. At the same time, antibiotic residues in soil may destroy microbial communities and promote the spread of antibiotic resistance genes, thereby affecting soil ecology. In addition, long-term exposure to antibiotics may also pose potential risks to human health, including allergic reactions and liver and kidney damage. With the increase in their use, the impact of quinolone antibiotic residues on the water environment, soil and ecosystem has received increasing attention. Quinolones are not only difficult to degrade naturally, but also exist in the environment for a long time, which may lead to the emergence and spread of drug-resistant bacteria, posing a new public health threat. Therefore, effective, rapid and accurate measures are urgently needed for antibiotic detection.

[0003] Traditional methods for detecting antibiotics include high performance liquid chromatography (HPLC), high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS), enzyme-linked immunosorbent assay (ELISA), and capillary electrophoresis (CE). These methods usually rely on expensive and complex equipment, have cumbersome operation processes, and require professional technicians to handle samples. They are mainly suitable for laboratory environments. In contrast, electrochemical sensing technology has shown great potential in the detection of antibiotics due to its advantages such as low cost, rapid response, high sensitivity, and simple operation. Summary of the invention

[0004] The invention provides a preparation method of an electrochemical sensor and application thereof in detecting quinolone antibiotics. The electrochemical sensor can selectively identify different types of quinolone antibiotics.

[0005] The purpose of the present invention is achieved through the following technical solutions: 1. Disperse the conductive carrier in a sodium hydroxide solution with a concentration of 40 g / L-200 g / L, perform ultrasonic treatment at 30°C-80°C for 0.5-4h, separate the solid from the liquid, wash the solid with deionized water, and dry to obtain a hydroxylated conductive carrier; The conductive carrier is selected from graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and carbon nitride; 2. The dried product was suspended in deionized water to prepare a dispersion with a concentration of 1 mg / mL-10 mg / mL, silver nitrate was added to the dispersion to a final concentration of 0.001 mg / mL-0.02 mg / mL, and after ultrasonic dispersion for 0.5-3 hours, an excess of reducing agent was added, and ultrasonic reduction was performed at 30°C-80°C for 2-5 hours, and the solid-liquid separation was performed. The solid was washed with deionized water and dried, and the dried product was dispersed in an ethanol aqueous solution to prepare a suspension with a concentration of 1 mg / mL. After ultrasonic treatment for 0.5 hours, the suspension was drop-coated on a working electrode (screen-printed electrode) to prepare an electrochemical sensor; The reducing agent is sodium borohydride, oxalic acid, ascorbic acid or glucose; the volume concentration of ethanol in the ethanol aqueous solution is 10-90%.

[0006] 3. The electrochemical sensor prepared by the above method is applied to the detection of quinolone antibiotics. 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 the electrochemical workstation respectively. The other ends of the working electrode, the counter electrode and the reference electrode are placed in the PBS electrolyte containing quinolone antibiotics. Differential pulse voltammetry is used for detection. The enrichment time is set to 5 to 120 seconds. The solution is stirred during the enrichment period. After the enrichment is completed, the stirring is stopped. After standing for 1 to 10 seconds, a set of scanning voltages with different scanning ranges are applied to the electrode system. Different potentials can be used to detect different quinolone antibiotics, thereby achieving effective identification of these antibiotics. The electrochemical workstation records the changes in current and voltage, generates a current-voltage curve, plots the standard curve corresponding to the antibiotic with the antibiotic concentration as the horizontal axis and the oxidation peak value as the vertical axis, obtains the regression equation, and thus determines the linear relationship between the antibiotic concentration and the peak current.

[0007] The sample to be tested is placed in an electrolytic cell and tested by an electrochemical workstation according to the above method to obtain the oxidation peak value corresponding to the antibiotic in the sample to be tested, which is substituted into the regression equation to calculate the content of the antibiotic in the sample to be tested.

[0008] The electrolyte is a PBS electrolyte with a pH value of 2-12 and a concentration of 0.1-1 mol / L.

[0009] Advantages and technical effects of the present invention: 1. Conductive carriers such as graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and carbon nitride all have large specific surface area, excellent conductivity, good chemical stability, and easy functionalization, which provide more surface active sites. Hydroxylation treatment introduces more hydrophilic hydroxyl groups to the surface of the conductive material, thereby improving its dispersibility in aqueous solution and increasing reactive sites, which is beneficial to the attachment and reduction of silver ions (Ag⁺); 2. The hydroxylated conductive carrier provides sufficient adsorption sites for Ag nanoparticles, thus effectively reducing the aggregation of Ag during the chemical reduction process. In addition, as a hydrophilic group, the hydroxyl group significantly improves the dispersibility of the material in aqueous solution; the combination of the two not only improves the electron transfer performance, but also enhances the adsorption capacity, thereby significantly improving the sensitivity of detection; The in situ generation of Ag nanoparticles provides excellent catalytic ability for subsequent electrochemical applications. Due to the adjustable particle size, combined with different potential detection methods, differentiated detection of different antibiotics can be achieved; 3. The electrochemical sensor prepared by the present invention has the ability to perform electrochemical detection of different quinolone antibiotics in aqueous solution. The research results show that the electrochemical sensor has high sensitivity and low detection limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the SEM image of Ag-OH-rGO; Figure 2 The response current peak value (a) and linear regression equation (b) of the Ag (30 ° C) -OH-rGO / SPEC electrochemical sensor in Example 1 when detecting different concentrations of ciprofloxacin in the voltage range of -0.15 V to 0.20 V using differential pulse voltammetry; Figure 3 The response current peak value (a) and linear regression equation (b) of the Ag (50 ° C) -OH-rGO / SPEC electrochemical sensor in Example 2 when detecting different concentrations of levofloxacin in the voltage range of -1.00 V to 2.50 V using differential pulse voltammetry; Figure 4 The peak value of the response current (a) and the linear regression equation (b) of the Ag (80 ° C) -OH-rGO / SPEC electrochemical sensor in Example 3 when detecting different concentrations of moxifloxacin in the voltage range of -0.08 V to 0.245 V using differential pulse voltammetry; Figure 5 TEM images of Ag nanoparticles of different sizes, where Figure a is Example 1, Figure b is Example 2, and Figure c is Example 3. DETAILED DESCRIPTION

[0011] The present invention is further described in detail below by way of examples, but the protection scope of the present invention is not limited to the contents described above; Example 1: Preparation method of electrochemical sensor and its application in ciprofloxacin detection 1. Dissolve 5 mg of reduced graphene oxide (rGO) in 20 mL of 50 g / L sodium hydroxide solution, ultrasonically treat at 30 ° C for 3 h, filter, wash the filter residue with deionized water for 3 times, dry at 60 ° C, and suspend the dried product in deionized water to obtain a 1 mg / mL OH-rGO dispersion. Add silver nitrate to the dispersion to a final concentration of 0.001 mg / ml. After ultrasonic dispersion for 1 hour, add excess reducing agent NaBH4, ultrasonically reduce at 30 ° C for 2 h, centrifuge, wash the solid with deionized water, dry at 60 ° C for 24 h, and disperse the dried product in ethanol aqueous solution (30%) to obtain a 1 mg / mL suspension. After ultrasonic treatment for 0.5 h, 4 μL of the suspension was drop-coated on the screen-printed electrode and dried to obtain the electrochemical sensor Ag (30 ° C) -OH-rGO / SPEC; SEM image of Ag (30 ° C) -OH-rGO / SPEC is shown in Figure 1 From the figure, it can be seen that Ag(30℃)-OH-rGO exists in the form of Ag nanoparticles loaded on layered rGO, and the layered wrinkled structure of rGO can be observed. This structure provides a large specific surface area for the distribution of Ag nanoparticles on its surface, allowing the growth of Ag nanoparticles. At the same time, the layered structure also serves as a buffer layer, making the composite material more stable and preventing Ag from reacting too violently during the chemical reaction process and causing particle agglomeration. The diameter of Ag nanoparticles is shown in TEM. Figure 5 As shown in a.

[0012] 2. Detection of Ciprofloxacin (1) The test instrument comprises an electrochemical workstation, an electrolytic cell, and the electrochemical sensor prepared in step (3) as a working electrode, one end of the working electrode, a counter electrode, and a reference electrode are respectively connected to the electrochemical workstation, and the other ends of the working electrode, the counter electrode, and the reference electrode are respectively placed in the electrolytic cell; (2) Place 15 mL of 0.1 mol / L PBS buffer solution (pH = 5) containing 0.15-13 μmol / L ciprofloxacin (CIP) in the electrolytic cell; select differential pulse voltammetry (DPV) on the electrochemical workstation; place a magnetic stirring bar in the electrolytic cell and set the stirring speed of the electric stirrer to 300 rpm; stop stirring the solution in the electrolytic cell immediately after the solution is stirred evenly, let it stand for 1 min, and then load a forward scanning voltage in the range of -0.10 V to 0.20 V on the working electrode. The electrochemical workstation records the change in current-voltage and obtains the current-voltage curve (e.g. Figure 2 a); With the concentration of ciprofloxacin (CIP) as the horizontal axis and the peak value of the oxidation peak as the vertical axis, the standard curve corresponding to ciprofloxacin was drawn, and linear regression was performed to obtain the linear relationship between the concentration of ciprofloxacin (CIP) and the peak current (as shown in Figure 2b); this linear relationship (standard curve) is used to quantitatively detect the concentration of ciprofloxacin to be measured; the linear relationship between the ciprofloxacin concentration and the peak current corresponding to this working electrode is: In the concentration range of 0.15~0.9 µM: Ip(µA)= 8.76571C CIP (µM)+1.428(R 2 =0.99994); In the concentration range of 1~13 µM: Ip(µA)=1.05545C CIP (µM)-9.48956(R 2 =0.99852); (3) Testing of samples to be tested 0.1 mol / L PBS buffer solutions containing 3, 15, and 40 μmol / L ciprofloxacin were tested using the same experimental method as step (2). The peak currents measured were substituted into the linear equation of step (2) to calculate the ciprofloxacin contents to be 2.84, 16.1, and 39.2 μmol / L, respectively.

[0013] Example 2: Preparation method of electrochemical sensor and its application in levofloxacin detection 1. Dissolve 5 mg of reduced graphene oxide (rGO) in 20 mL of 80 g / L sodium hydroxide solution, ultrasonically treat at 50 ° C for 2 h, filter, wash the filter residue with deionized water three times, dry at 60 ° C, and suspend the dried product in deionized water to obtain a dispersion with a concentration of 1 mg / mL. Add silver nitrate to the dispersion to a final concentration of 0.01 mg / mL. After ultrasonic dispersion for 2 hours, add excess ascorbic acid, ultrasonically reduce at 50 ° C for 3 h, centrifuge, wash the solid with deionized water, dry at 60 ° C for 24 h, and disperse the dried product in ethanol aqueous solution (50%) to obtain a suspension with a concentration of 1 mg / mL. After ultrasonic treatment for 0.5 h, 4 μL of the suspension was drop-coated on the screen-printed electrode and dried to obtain the electrochemical sensor Ag (50 ° C) -OH-rGO / SPEC; the size of the Ag nanoparticles is shown in TEM. Figure 5 As shown in b.

[0014] 2. Preparation of standard curve is the same as in Example 1, except that a forward scanning voltage of -1.00V to 2.50V is applied to the working electrode. The current-voltage curve is shown in Figure 3 a; The linear relationship between levofloxacin concentration and peak current is (e.g. Figure 3 b): In the concentration range of 1~13µM: Ip=1.68609C LEV +2.28188(R 2 =0.99389) The 0.1 mol / L PBS buffer solution containing 5, 30, and 80 μmol / L levofloxacin was tested, and the test results showed that the contents of levofloxacin were 4.98, 30.72, and 79.69 μmol / L, respectively.

[0015] Example 3: Preparation method of electrochemical sensor and its application in moxifloxacin detection 1. Dissolve 5 mg of reduced graphene oxide (rGO) in 20 mL of 160 g / L sodium hydroxide solution, ultrasonically treat at 80 ° C for 0.5 h, filter, wash the filter residue with deionized water three times, dry at 60 ° C, and suspend the dried product in deionized water to obtain a dispersion with a concentration of 8 mg / mL. Add silver nitrate to the dispersion to a final concentration of 0.02 mg / mL. After ultrasonic dispersion for 3 hours, add excess glucose, ultrasonically reduce at 80 ° C for 2 h, centrifuge, wash the solid with deionized water, dry at 60 ° C for 24 h, and disperse the dried product in ethanol aqueous solution (85%) to obtain a suspension with a concentration of 1 mg / mL. After ultrasonic treatment for 0.5 h, 4 μL of the suspension was drop-coated on the screen-printed electrode and dried to obtain the electrochemical sensor Ag (80 ° C) -OH-rGO / SPEC; the size of the Ag nanoparticles is shown in TEM. Figure 5 As shown in c; 2. Preparation of standard curve is the same as in Example 1, except that a forward scanning voltage of -0.08V to 0.24V is applied to the working electrode. The current-voltage curve is shown in Figure 4 a; The linear relationship between moxifloxacin concentration and peak current is (e.g. Figure 4 b): In the concentration range of 1~13 µM: Ip=1.22081C MOX +7.92652 (R 2 =0.95235) The 0.1 mol / L PBS buffer solution containing 10, 15, and 20 μmol / L moxifloxacin was tested, and the test results showed that the content of moxifloxacin was 10.02, 18.60, and 18.97 μmol / L, respectively.

Claims

1. A method for preparing an electrochemical sensor, characterized in that: The conductive carrier is dispersed in a sodium hydroxide solution, ultrasonically treated at 30°C-80°C for 0.5-4h, and the solid is separated from the liquid. The solid is washed with deionized water, dried and suspended in deionized water to prepare a dispersion with a concentration of 1mg / mL-10mg / mL. Silver nitrate is added to the dispersion to a final concentration of 0.001-0.02mg / mL. After ultrasonic dispersion for 0.5-3h, an excess amount of reducing agent is added, and ultrasonic reduction is carried out at 30°C-80°C for 2-5h. The solid is separated from the liquid, the solid is washed with deionized water, dried, and the dried product is dispersed in an ethanol aqueous solution. After ultrasonic treatment for 0.5h, the suspension is drop-coated on a working electrode to prepare an electrochemical sensor.

2. The method for preparing an electrochemical sensor according to claim 1, characterized in that: The conductive carrier is selected from graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and carbon nitride.

3. The method for preparing an electrochemical sensor according to claim 1, characterized in that: The concentration of sodium hydroxide solution is 40g / L-200g / L.

4. The method for preparing an electrochemical sensor according to claim 1, characterized in that: The reducing agent is sodium borohydride, oxalic acid, ascorbic acid or glucose.

5. The method for preparing an electrochemical sensor according to claim 1, characterized in that: The volume concentration of ethanol in the ethanol aqueous solution is 10-90%.

6. Use of the electrochemical sensor prepared by the preparation method of the electrochemical sensor according to claim 1 in the detection of quinolone antibiotics.

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