A method for detecting furacilin based on molecular imprinting sensor

Abstract

The present invention discloses an electrochemical sensor based on a molecular imprinting membrane and uses it for the detection of furacilin. The method uses a molecular imprinting membrane modified electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode, and an Ag / AgCl electrode as a reference electrode to form a three-electrode system for high-selectivity and rapid detection of furacilin. The steps for preparing the molecular imprinting membrane modified electrode are as follows: (1) preparing graphene oxide by a Hummers improved method; (2) preparing a gold nanoparticle / reduced graphene oxide modified electrode by an electrodeposition method; (3) using furacilin as a template molecule and preparing a molecular imprinting membrane by an electropolymerization method, which is a sensor for detecting furacilin. The present invention provides a method for highly selectively detecting furacilin by an electrochemical sensor based on a molecular imprinting membrane.

Description

Technical Field

[0001] The invention relates to a method for detecting furacilin in food using an electrochemical sensor based on a molecular imprinting membrane, and belongs to the technical field of electrochemical analysis and detection. Background Art

[0002] Furacilin, 5-nitro-2-furancarboxaldehyde semicarbazone. It is a synthetic antibacterial drug that has been widely used in animal husbandry and aquaculture due to its excellent antibacterial effect and cost advantage. However, studies have found that the residues of furacilin and its metabolites in animal-derived foods can be transmitted to humans through the food chain. Long-term intake can cause various diseases and have side effects such as carcinogenicity and teratogenicity. my country's Ministry of Agriculture has banned the use of furacilin on humans and animals. However, due to its high antibacterial efficiency and low cost, it is still used by lawless elements. Therefore, it is of great significance to conduct highly selective detection of furacilin drug residues in food.

[0003] At present, the methods commonly used to detect furacilin mainly include: gas chromatography, high performance liquid chromatography, mass spectrometry, etc., but the above methods all have the disadvantages of complex operation, high cost and environmental pollution. Summary of the invention

[0004] The present invention aims to solve the problems existing in the existing analytical methods for detecting furacilin, combines the advantages of high selectivity of molecular imprinting materials with high sensitivity and simple and quick operation of electrochemical sensors, and provides a method for detecting furacilin using an electrochemical sensor based on a molecular imprinting membrane.

[0005] Compared with existing detection methods, electrochemical analysis methods have the advantages of good selectivity, high sensitivity, less time consumption, simple operation and rapid response.

[0006] The technical scheme of the present invention is as follows: the present invention introduces graphene and gold nanoparticles as sensitizing nanomaterials of the electrode, which can effectively increase the specific surface area of ​​the electrode and increase the number of recognition sites, and then the modified electrode is placed in a polymerization solution of furacilin and functional monomers to prepare a molecular imprinting membrane on the electrode by an electropolymerization method. After that, furacilin is eluted by a chemical solution to prepare a molecular imprinting electrochemical sensor. The sensor is placed in a furacilin solution for adsorption, and the high selectivity of the molecular imprinting membrane is used to enhance the recognition ability of the sensor.

[0007] The specific steps of the molecular imprinted membrane modified electrode preparation method are as follows:

[0008] (1) Pretreatment of glassy carbon electrode: The glassy carbon electrode was polished to a mirror surface on suede with 0.50 and 0.05 μm alumina powder, and then ultrasonically cleaned with deionized water and ethanol for 1 min respectively. After each ultrasonic cleaning, it was rinsed with deionized water to obtain a pretreated glassy carbon electrode.

[0009] (2) Using graphite powder as raw material, graphene oxide was prepared by Hummers' modified method;

[0010] (3) ultrasonically dispersing 0.2 g of graphene oxide in 20 mL of PBS buffer solution with a pH of 8 to obtain a graphene oxide suspension; placing the glassy carbon electrode pretreated in step (1) in the above graphene oxide dispersion, using a platinum electrode as an auxiliary electrode and an Ag / AgCl electrode as a reference electrode, using cyclic voltammetry at a scan rate of 50 mV / s, a voltage range of -1.4 V to 0 V, and scanning for 5 to 25 cycles to obtain a reduced graphene oxide modified electrode;

[0011] (4) placing the reduced graphene oxide modified electrode in a 5 mmol / L HAuCl4 solution, and using a constant current method to deposit gold nanoparticles on the electrode at -1.0 mV for 300 s to 700 s to obtain a gold nanoparticle / reduced graphene oxide modified electrode;

[0012] (5) Using acetate buffer as solvent, furacillin as target molecule and o-phenylenediamine as functional monomer, a polymerization solution is obtained; placing a gold nanoparticle / reduced graphene oxide modified electrode in the above polymerization solution, using a platinum sheet electrode as auxiliary electrode and an Ag / AgCl electrode as reference electrode, and using cyclic voltammetry to electropolymerize the molecular imprinting membrane on the electrode, and then taking it out and rinsing it for use.

[0013] (6) The modified electrode obtained in (5) was eluted in a prepared methanol and acetic acid mixture for 15-30 min to obtain a molecular imprinting membrane / gold nanoparticle / reduced graphene oxide modified electrode, which is a sensor for detecting furacilin.

[0014] Furthermore, in step (5), the molar ratio of furacilin to o-phenylenediamine is 1:6; the cyclic voltammetry parameters in step (5) are: scanning voltage range: 0 V-0.8 V, scanning rate 50 mV / s, scanning number 15 circles; the elution conditions in step (6) are: V 甲醇 : V 乙酸 =8:2.

[0015] The present invention uses the electrochemical sensor based on molecular imprinting membrane to detect furacilin in food as follows:

[0016] a. Prepare different concentrations of furacilin aqueous solutions using deionized water;

[0017] b. Place the above molecular imprinted membrane modified electrode in a furazolidinone aqueous solution for adsorption for 20 min;

[0018] c. The above adsorbed electrode was used as the working electrode, the platinum electrode was used as the auxiliary electrode, and the Ag / AgCl electrode was used as the reference electrode to form a three-electrode system, and the system was placed in a 2.5 mmol / L potassium ferrocyanide solution;

[0019] d. Using [Fe(CN)6] 3- / 4- As a redox probe, differential pulse voltammetry was used to obtain the current values ​​corresponding to the adsorption of different concentrations of furacilin, and a standard curve was drawn with the peak current difference as the ordinate and the concentration as the abscissa;

[0020] e. Place the molecular imprinting membrane modified electrode in an aqueous solution of unknown concentration of furacilin for adsorption, then form a three-electrode system and place it in a potassium ferrocyanide solution to detect the corresponding current value, and calculate the concentration of furacilin based on the standard curve.

[0021] Furthermore, the electrochemical parameters of the differential pulse voltammetry are: scanning potential range: -0.2 V-0.6 V, scanning rate: 100 mV / s.

[0022] Compared with the prior art, the present invention has the beneficial effect that the present invention forms a molecular imprinting membrane by electropolymerization to prepare a sensor on the surface of a graphene and gold nanoparticle modified electrode. Due to the signal amplification effect of graphene and gold nanoparticles and the high selectivity of the molecular imprinting membrane, a method for highly selectively detecting the harmful substance furacilin by a molecular imprinting electrochemical sensor is provided. The sensor prepared by the present invention is used to detect furacilin. Compared with other methods for detecting furacilin, the sensor has simple equipment, convenient operation, good selectivity and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flow chart for the preparation of molecular imprinted membrane modified electrodes;

[0024] Figure 2 Cyclic voltammograms of different modified electrodes: (a) bare glassy carbon electrode, (b) reduced graphene oxide modified electrode, (c) gold nanoparticles / reduced graphene oxide modified electrode, (d) molecular imprinted membrane / gold nanoparticles / reduced graphene oxide modified electrode (before elution), (e) molecular imprinted membrane / gold nanoparticles / reduced graphene oxide modified electrode (after elution), (f) molecular imprinted membrane / gold nanoparticles / reduced graphene oxide modified electrode (after adsorption);

[0025] Figure 3Differential pulse voltammograms of different modified electrodes: (a) bare glassy carbon electrode, (b) reduced graphene oxide modified electrode, (c) gold nanoparticles / reduced graphene oxide modified electrode, (d) molecular imprinting membrane / gold nanoparticles / reduced graphene oxide modified electrode (before elution), (e) molecular imprinting membrane / gold nanoparticles / reduced graphene oxide modified electrode (after elution), (f) molecular imprinting membrane / gold nanoparticles / reduced graphene oxide modified electrode (after adsorption);

[0026] Figure 4 This is the detection performance diagram of the sensor for furacilin;

[0027] Figure 5 The standard curve of the sensor response signal versus the concentration of furacilin. DETAILED DESCRIPTION

[0028] The present invention is further described below by means of specific examples. The following examples are helpful for those skilled in the art to understand the present invention in detail, but in no way limit the scope of protection of the present invention.

[0029] Example 1

[0030] Preparation of molecular imprinting sensor based on gold nanoparticles / reduced graphene oxide, the preparation steps are as follows Figure 1 shown.

[0031] (1) Pretreatment of glassy carbon electrode: The glassy carbon electrode was polished to a mirror surface on suede with 0.50 and 0.05 μm alumina powder, and then ultrasonically cleaned with deionized water and ethanol for 1 min respectively. After each ultrasonic cleaning, it was rinsed with deionized water to obtain a pretreated glassy carbon electrode.

[0032] (2) Using graphite powder as raw material, graphene oxide was prepared by Hummers' modified method;

[0033] (3) ultrasonically dispersing 0.2 g of graphene oxide in 20 mL of PBS buffer at pH = 8 to obtain a graphene oxide suspension; placing the glassy carbon electrode pretreated in step (1) in the above graphene oxide dispersion, using a platinum electrode as an auxiliary electrode and an Ag / AgCl electrode as a reference electrode, using cyclic voltammetry at a scan rate of 50 mV / s, a voltage range of -1.4 V to 0 V, and scanning for 15 cycles to obtain a reduced graphene oxide modified electrode;

[0034] (4) The reduced graphene oxide modified electrode was placed in a 5 mmol / L HAuCl4 solution, and gold nanoparticles were deposited on the electrode by a constant current method at -1.0 mV for 300 s to obtain a gold nanoparticle / reduced graphene oxide modified electrode;

[0035] (5) using acetic acid buffer as solvent, furazolidinone as target molecule, and o-phenylenediamine as functional monomer to obtain a polymerization solution; placing a gold nanoparticle / reduced graphene oxide modified electrode in the polymerization solution, electropolymerizing the molecular imprinting membrane on the electrode by cyclic voltammetry, and then taking out and rinsing it for use;

[0036] (6) The modified electrode obtained in (5) was eluted in a prepared methanol and acetic acid mixture for 20 min to obtain a molecular imprinting membrane / gold nanoparticles / reduced graphene oxide modified glassy carbon electrode, which is a sensor for detecting furacilin.

[0037] Example 2

[0038] Fabrication of sensors based on gold nanoparticle / reduced graphene oxide molecularly imprinted films.

[0039] (1) Pretreatment of glassy carbon electrode: The glassy carbon electrode was polished to a mirror surface on suede with 0.50 and 0.05 μm alumina powder, and then ultrasonically cleaned with deionized water and ethanol for 1 min respectively. After each ultrasonic cleaning, it was rinsed with deionized water to obtain a pretreated glassy carbon electrode.

[0040] (2) Using graphite powder as raw material, graphene oxide was prepared by Hummers' modified method;

[0041] (3) ultrasonically dispersing 0.2 g of graphene oxide in 20 mL of PBS buffer solution with a pH of 8 to obtain a graphene oxide suspension; placing the glassy carbon electrode pretreated in step (1) in the graphene oxide dispersion, using a platinum electrode as an auxiliary electrode and an Ag / AgCl electrode as a reference electrode, using cyclic voltammetry at a scan rate of 50 mV / s, a voltage range of -1.4 V to 0 V, and scanning for 25 cycles to obtain a reduced graphene oxide modified electrode;

[0042] (4) The reduced graphene oxide modified electrode was placed in a 5 mmol / L HAuCl4 solution, and gold nanoparticles were deposited on the electrode by a constant current method at -1.0 mV for 700 s to obtain a gold nanoparticle / reduced graphene oxide modified electrode;

[0043] (5) using acetic acid buffer as solvent, furazolidinone as target molecule, and o-phenylenediamine as functional monomer to obtain a polymerization solution; placing a gold nanoparticle / reduced graphene oxide modified electrode in the polymerization solution, electropolymerizing the molecular imprinting membrane on the electrode by cyclic voltammetry, and then taking out and rinsing it for use;

[0044] (6) The modified electrode obtained in (5) was eluted in a prepared methanol and acetic acid mixture for 30 min to obtain a molecular imprinting membrane / gold nanoparticle / reduced graphene oxide modified electrode, which is a sensor for detecting furacilin.

[0045] Example 3

[0046] Fabrication of sensors based on gold nanoparticle / reduced graphene oxide molecularly imprinted films.

[0047] (1) Pretreatment of glassy carbon electrode: The glassy carbon electrode was polished to a mirror surface on suede with 0.50 and 0.05 μm alumina powder, and then ultrasonically cleaned with deionized water and ethanol for 1 min respectively. After each ultrasonic cleaning, it was rinsed with deionized water to obtain a pretreated glassy carbon electrode.

[0048] (2) Using graphite powder as raw material, graphene oxide was prepared by Hummers' modified method;

[0049] (3) ultrasonically dispersing 0.2 g of graphene oxide in 20 mL of PBS buffer solution with a pH of 8 to obtain a graphene oxide suspension; placing the glassy carbon electrode pretreated in step (1) in the above graphene oxide dispersion, using a platinum electrode as an auxiliary electrode and an Ag / AgCl electrode as a reference electrode, using cyclic voltammetry at a scan rate of 50 mV / s, a voltage range of -1.4 V to 0 V, and scanning for 20 cycles to obtain a reduced graphene oxide modified electrode;

[0050] (4) placing the reduced graphene oxide modified electrode in a 5 mmol / L HAuCl4 solution, and using a constant current method to deposit gold nanoparticles on the electrode at -1.0 mV for 500 s to obtain a gold nanoparticle / reduced graphene oxide modified electrode;

[0051] (5) using acetic acid buffer as solvent, furazolidinone as target molecule, and o-phenylenediamine as functional monomer to obtain a polymerization solution; placing a gold nanoparticle / reduced graphene oxide modified electrode in the polymerization solution, electropolymerizing the molecular imprinting membrane on the electrode by cyclic voltammetry, and then taking out and rinsing it for use;

[0052] (6) The modified electrode obtained in (5) was eluted in a prepared methanol and acetic acid mixture for 25 min to obtain a molecular imprinting membrane / gold nanoparticle / reduced graphene oxide modified electrode, which is a sensor for detecting furacilin.

[0053] Example 4

[0054] The sensor obtained in Example 3 was used for electrochemical testing:

[0055] (1) Cyclic voltammetry test of the sensor.

[0056] The molecular imprinted membrane modified electrode before elution, after elution, and after adsorption in furazolidinone solution was used as the working electrode, the platinum electrode was used as the auxiliary electrode, and the Ag / AgCl electrode was used as the reference electrode to form a three-electrode system. The system was placed in a 2.5 mmol / L potassium ferrocyanide solution for cyclic voltammetry scanning. The scanning parameters were: voltage range of -0.1 V to 0.6 V, scanning rate of 50 mV / s. The cyclic voltammetry diagram is shown in Figure 2 ,from Figure 2 It can be seen that before the molecular imprinting membrane was eluted, the molecular imprinting membrane occupied the electrode surface, which hindered the electron transfer between the redox probe and the electrode; after the molecular imprinting membrane was eluted, the peak current signal of potassium ferrocyanide increased significantly, because the template molecule furacilin in the imprinting membrane was eluted, leaving specific recognition holes, making electron exchange easier; after the eluted molecular imprinting membrane modified electrode was immersed in furacilin solution, some specific holes were occupied by furacilin, which hindered the electron transfer, so the peak current became smaller again.

[0057] (2) Differential pulse voltammetry test of the sensor:

[0058] The molecular imprinted membrane modified electrode was used as the working electrode, the platinum electrode as the auxiliary electrode, and the Ag / AgCl electrode as the reference electrode to form a three-electrode system. The system was placed in a 2.5 mmol / L potassium ferrocyanide solution for differential pulse voltammetry scanning. The scanning parameters were: scanning potential range: -0.2 V-0.6 V, scanning rate of 100 mV / s. The eluted molecular imprinted membrane modified electrode was placed in a potassium ferrocyanide solution, and the blank current I0 was obtained by scanning; then the electrode was placed in a certain concentration of furazolidone solution for adsorption, and the current I was obtained by scanning again. The response current of the sensor is ΔI = I - I 0 The results of the measurement are shown in Figure 3 , Figure 4 and Figure 5 The linear range of furacilin determination was 5-1000 nmol / L, and the detection limit was 0.18 nmol / L. The sensor was placed at 4°C for two weeks, and its response current value was approximately 94.78% of the original signal.

Claims

1. A method for detecting nitrofurazone based on molecular imprinting sensor, characterized in that: The method uses a molecular imprinting membrane modified electrode as a working electrode, a platinum sheet electrode as an auxiliary electrode, and an Ag / AgCl electrode as a reference electrode to form a three-electrode system for high-selectivity and rapid detection of furacilin; The specific construction method of the molecular imprinting sensor is as follows: (1) Pretreatment of glassy carbon electrode: The glassy carbon electrode was polished to a mirror surface on suede with 0.50 and 0.05 μm alumina powder, and then ultrasonically cleaned with deionized water and ethanol for 1 min respectively. After each ultrasonic cleaning, it was rinsed with deionized water to obtain a pretreated glassy carbon electrode. (2) Using graphite powder as raw material, graphene oxide was prepared by Hummers' modified method; (3) ultrasonically dispersing 0.2 g of graphene oxide in 20 mL of PBS buffer at pH = 8 to obtain a graphene oxide suspension; placing the glassy carbon electrode pretreated in step (1) in the graphene oxide dispersion, using a platinum electrode as an auxiliary electrode and an Ag / AgCl electrode as a reference electrode, using cyclic voltammetry at a scan rate of 50 mV / s, a voltage range of -1.4 V–0 V, and scanning for 5–25 cycles to obtain a reduced graphene oxide modified electrode; (4) placing the reduced graphene oxide modified electrode in a 5.0 mmol / L HAuCl4 solution, and using a constant current method to deposit gold nanoparticles on the electrode at -1.0 mV for 300 s-700 s to obtain a gold nanoparticle / reduced graphene oxide modified electrode; (5) using acetate buffer as solvent, furazolidinone as target molecule, and o-phenylenediamine as functional monomer to obtain a polymerization solution; placing a gold nanoparticle / reduced graphene oxide modified electrode in the polymerization solution, electropolymerizing the molecular imprinting membrane on the electrode by cyclic voltammetry, and then taking out and rinsing it for standby use; (6) The modified electrode obtained in (5) was eluted in a prepared methanol and acetic acid mixture for 15-30 min to obtain a molecular imprinting membrane / gold nanoparticle / reduced graphene oxide modified electrode, which is a sensor for detecting furacilin.

2. The method for detecting nitrofurazone based on molecular imprinting sensor according to claim 1, characterized in that: The molar ratio of furacilin to o-phenylenediamine in step (5) is 1:

6.

3. The method for detecting nitrofurazone based on molecular imprinting sensor according to claim 1, characterized in that: The cyclic voltammetry parameters in step (5) are as follows: scanning voltage range: 0 V-0.8 V, scanning rate 50 mV / s, and scanning number 15 cycles.

4. The method for detecting nitrofurazone based on molecular imprinting sensor according to claim 1, characterized in that: The elution conditions in step (6) are: 甲醇 :V 乙酸 =8:

2.

5. The method for detecting nitrofurazone based on molecular imprinting sensor according to claim 1, characterized in that: The step of the sensor detecting furacilin comprises: a. Prepare different concentrations of furacilin aqueous solutions using deionized water; b. placing the molecular imprinted membrane modified electrode in an aqueous solution of furazolidone for 20 min; c. The above-mentioned adsorbed electrode was used as the working electrode, the platinum electrode was used as the auxiliary electrode, and the Ag / AgCl electrode was used as the reference electrode to form a three-electrode system, and the system was placed in a 2.5 mmol / L potassium ferrocyanide solution; d. Using [Fe(CN)6] 3- / 4- As a redox probe, differential pulse voltammetry was used to obtain the current values ​​corresponding to the adsorption of different concentrations of furacilin; the peak current value obtained by subtracting the current value after the elution of furacilin from the current value after the adsorption of furacilin was used as the ordinate, and the concentration of furacilin was used as the abscissa to draw a standard curve; e. Place the molecular imprinting membrane modified electrode in an aqueous solution of unknown concentration of furacilin for adsorption, then form a three-electrode system and place it in a potassium ferrocyanide solution to detect the corresponding current value, and calculate the concentration of furacilin based on the standard curve.

6. The method for detecting furacilin based on molecular imprinting sensor according to claim 5, characterized in that: The electrochemical parameters of the differential pulse voltammetry method are as follows: the scanning potential range is -0.2V-0.6V, and the scanning rate is 100mV / s.

Images