Electrochemical sensor electrode and preparation method and application thereof

Abstract

The invention discloses an electrochemical sensor electrode as well as a preparation method and application thereof. The electrochemical sensor electrode comprises a conductive substrate and a BiOCl / Bi24O31Cl10 / TiO2 composite material, wherein the BiOCl / Bi24O31Cl10 / TiO2 composite material is loaded on the conductive substrate. According to the BiOCl / Bi24O31Cl10 / TiO2 composite material disclosed by the invention, the problem of low conductivity of the composite material can be further improved through mutual synergistic effect of the BiOCl / Bi24O31Cl10 / TiO2 composite material, and the current value is further increased. The electrochemical sensor disclosed by the invention can be used for rapidly detecting cefquinome, sample pretreatment is relatively simple, the detection time is short, and too much technical operation is not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical detection, and particularly relates to an electrochemical sensor electrode, a preparation method thereof and an application thereof. Background Art

[0002] Cefquinome sulfate is the first fourth-generation cephalosporin antibiotic specifically for animals, and has the characteristics of broad antibacterial spectrum, strong antibacterial activity, stable to β-lactamase, not easy to produce drug resistance, low toxicity, and less residue. Cefquinome is a white or off-white crystalline powder, slightly soluble in water, with a pH of 1.5 - 2.5; the solubility at pH 7.0 is 11 - 12 mg / mL, unstable and easy to decompose in high-temperature and humid environments, and cefquinome has a low absorption rate in the digestive tract, and its dry powder of sulfate is relatively stable. Therefore, it is usually made into the form of sulfate clinically, which is an off-white or light yellow crystalline powder, and the molecular formula is C 23 H 24 N 6 O 5 S 2 ·H 2 SO 4 。The mechanism of action of cefquinome lies in that the β-lactam structure binds to the carboxypeptidase, transpeptidase and endopeptidase of bacteria to inhibit the formation of peptidoglycan, directly preventing the synthesis of the cell wall of bacteria in the reproductive period. The bacterial cell wall is damaged, water penetrates into the bacteria, resulting in the final rupture of the bacteria, thus playing a bactericidal role. Based on the above characteristics of cefquinome, it has begun to be applied to the clinical treatment of pigs and cattle in China. However, in the process of preventing and treating animal diseases or using it as a feed additive in animal feed, due to misuses, abuses and non-compliance with the drug withdrawal period and other behaviors, residues in meat and milk exceed the standard. Long-term consumption of foods containing excessive cephalosporins will have various toxic effects on the human body, such as allergies, damage to the liver and kidneys, causing adverse reactions in the gastrointestinal tract, and also causing certain harm to the nervous system.

[0003] At present, the detection methods for cephalosporin antibiotics include large-scale instrument detection methods such as gas chromatography, high-performance liquid chromatography, gas chromatography-mass spectrometry, and high-performance liquid chromatography-tandem mass spectrometry, as well as electrochemical sensor methods. Although the instrument detection methods have high sensitivity and strong specificity, they also have certain limitations. For example, the detection instruments are expensive, the sample pretreatment is complex and time-consuming, etc., and professional operators are required during detection. The current national standard detection method also includes the microbial detection method. As a traditional classic method, the microbial detection method is the most important detection method in the current national standard method. Substances with low content and lower than the instrument detection limit still need to be determined by the microbial method, but this method has defects such as long time consumption, low accuracy, and poor repeatability. Currently, there is also photoelectrochemical detection for the detection of antibiotics. When using the photoelectrochemical detection method to detect cefquinome, first, when selecting materials, not only the photocurrent of each material needs to be considered, but also whether the conduction band and valence band of each material match; furthermore, the recognition element used in the photoelectrochemical detection method for detecting antibiotics is the aptamer, and the development of the cefquinome aptamer requires a large amount of cost. Summary of the Invention

[0004] The present invention aims to at least solve the above technical problems existing in the prior art. For this reason, the object of the present invention is to provide an electrochemical sensor electrode and its preparation method and application.

[0005] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0006] In the first aspect of the present invention, there is provided an electrochemical sensor electrode, including a conductive substrate and BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material loaded on the conductive substrate.

[0007] TiO 2 is an electrode material with relatively wide application, having stable chemical properties and not being easily decomposed. Titanium dioxide is a semiconductor material with a wide bandgap, which will lead to low electrical conductivity of its electrons. Compared with a single TiO 2 material, the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material can further improve the problem of its low electrical conductivity through the mutual synergistic effect of each other, and the current value will also increase further.

[0008] In some embodiments of the present invention, the BiOCl / Bi 24 O 31 Cl10 / TiO 2 The deposition amount of the composite material is 1-6 mg / cm 2 , such as 2-4.5 mg / cm 2 , 2.5-4.2 mg / cm 2 .

[0009] In some embodiments of the present invention, the conductive substrate includes any one of a metal substrate, a carbon material substrate, and a conductive glass substrate.

[0010] In some embodiments of the present invention, the material of the conductive substrate includes FTO, ITO, AZO, ZnO:B, ZnO:Ga, ZnO:In, Cd 2 SnO 4 , Zn 2 SnO 4 , TiO 2 :Nb, SrTiO 3 :Nb, CuS, CuAlO 2 , CuAlS 2 , Pt, Au, Ti, Pd, Ir, Ag, Ru, Ni, STS, Al, Mo, Cr, Cu, W.

[0011] In some embodiments of the present invention, the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 In the composite material, the molar ratio of BiOCl / Bi 24 O 31 Cl 10 to TiO 2 is 1:(1-2).

[0012] In some embodiments of the present invention, in the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material, the mass ratio of BiOCl to Bi 24 O 31 Cl 10 is 1:1.5-2.5, such as 1:2.

[0013] The second aspect of the present invention provides a method for preparing the electrochemical sensor electrode described above, including the following steps:

[0014] S1: Place TiO 2 in a mixed solution of bismuth salt and chloride salt, carry out hydrothermal reaction and then calcine to obtain BiOCl / Bi 24 O 31Cl 10 / TiO 2 Composite material;

[0015] S2: Apply the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material solution onto a conductive substrate to obtain the electrochemical sensor electrode described above.

[0016] In some embodiments of the present invention, the bismuth salt includes at least one of bismuth nitrate pentahydrate, bismuth sulfate, or a bismuth ion complex.

[0017] In some embodiments of the present invention, the chloride salt includes at least one of sodium chloride, potassium chloride, and magnesium chloride.

[0018] In some embodiments of the present invention, the molar ratio of TiO 2 , bismuth salt, and chloride salt is (1 - 2):1:(0.5 - 1).

[0019] In some embodiments of the present invention, the molar ratio of bismuth salt to chloride salt in the mixed solution is 1:(0.5 - 1).

[0020] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 150°C - 180°C; the time of the hydrothermal reaction is 12 - 48 h.

[0021] In some embodiments of the present invention, the temperature of the calcination is 400 - 500°C, the time is 0.5 - 2 h; the heating rate is 1 - 5°C / min.

[0022] In some embodiments of the present invention, the preparation method of TiO 2 includes the following steps: subject a titanate ester, an acid inhibitor, and an alcohol organic solvent to a hydrothermal reaction to obtain the TiO 2 ; the temperature of the hydrothermal reaction is 160 - 180°C, and the time is 3 - 5 h.

[0023] In some embodiments of the present invention, the titanate ester includes at least one of tetrabutyl titanate, tetraisobutyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetraethyl titanate, and tetramethyl titanate.

[0024] In some embodiments of the present invention, the acid inhibitor includes at least one of sulfuric acid, hydrochloric acid, and nitric acid.

[0025] In some embodiments of the present invention, the alcohol organic solvent includes at least one of ethanol, butanol, and ethylene glycol.

[0026] The third aspect of the present invention provides a molecularly imprinted electrochemical sensor, including the electrochemical sensor electrode described above.

[0027] In some embodiments of the present invention, the surface of the electrochemical sensor electrode is further modified with a molecularly imprinted polymer.

[0028] In some embodiments of the present invention, the molecularly imprinted polymer is formed from a template molecule 7-aminocephalosporanic acid and a functional monomer.

[0029] In some embodiments of the present invention, the functional monomer includes at least one of o-phenylenediamine (OPD), 3,3’,5,5’-tetramethylbenzidine (TMB), 3,3’-diaminobenzidine tetrahydrochloride (DAB), and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS).

[0030] In some embodiments of the present invention, the molar ratio of 7-aminocephalosporanic acid to the functional monomer is 1:2 to 4.

[0031] In some embodiments of the present invention, the modification method includes cyclic voltammetry; the potential range of the cyclic voltammetry is 0 to 1 V, such as 0 to 0.8 V, the scanning speed is 40 to 60 mV / s; and the number of cycles is 5 to 30 times.

[0032] In some embodiments of the present invention, the modification method further includes eluting 7-aminocephalosporanic acid after cyclic voltammetry.

[0033] The fourth aspect of the present invention provides a method for detecting 7-aminocephalosporanic acid, including the following steps: incubating the electrochemical sensor electrode or the molecularly imprinted electrochemical sensor with 7-aminocephalosporanic acid, and testing the current by voltammetry to obtain the concentration of 7-aminocephalosporanic acid.

[0034] The fifth aspect of the present invention provides the application of the electrochemical sensor electrode or the molecularly imprinted electrochemical sensor in detecting 7-aminocephalosporanic acid.

[0035] In some embodiments of the present invention, the 7-aminocephalosporanic acid includes at least one of cephalexin, cefradine, cefdinir, cefapirin, cefixime, cefazolin, cefpirome, cefquinome, and cefoperazone.

[0036] In some embodiments of the present invention, the 7-aminocephalosporanic acid includes 7-aminocephalosporanic acid in food and sewage.

[0037] The beneficial effects of the present invention are:

[0038] The BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material can further improve the problem of its low conductivity through the mutual synergistic effect of each other, and the current value will also increase further.

[0039] In the present invention, a molecularly imprinted polymer is used as the recognition element. Since the molecularly imprinted polymer has high specificity, it can selectively bind to the biomolecule or biological activity to be detected, avoiding non-specific binding with other molecules, thereby improving the specificity of detection.

[0040] The electrochemical sensor of the present invention can quickly detect cefquinome. The sample pretreatment is relatively simple, the detection time is short, and not too many technical operations are required. Brief Description of the Drawings

[0041] Figure 1 It is the preparation process of the molecularly imprinted electrochemical sensor in the embodiment of the present invention.

[0042] Figure 2 It is the cyclic voltammogram of the modified electrodes of different materials in potassium ferricyanide in Test Example 1 of the present invention.

[0043] Figure 3 It is the impedance diagram of different modified electrodes in potassium ferricyanide in Test Example 1 of the present invention, (a): TiO 2 ; (b) BiOCl / Bi 24 O 31 Cl 10 ; (c) BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (d) MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (e) MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (f) Incubate MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 in a 0.25 mg / mL cefquinome solution for 25 min.

[0044] Figure 4This is the experimental result of square wave voltammetry after the molecularly imprinted electrochemical sensor in Example 5 of the present invention was incubated in cefquinome solutions with different concentrations for 25 min.

[0045] Figure 5 This is the relationship diagram between the current value and the logarithm of cefquinome concentration in Example 5 of the present invention. Detailed implementation manners

[0046] The content of the present invention will be further described in detail through specific examples below. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0047] Figure 1 This is the preparation process of the molecularly imprinted electrochemical sensor in the example of the present invention.

[0048] Example 1

[0049] In this example, BiOCl / Bi 24 O 31 Cl 10 was prepared. The specific process was as follows:

[0050] Preparation of BiOCl / Bi 24 O 31 Cl 10 by hydrothermal method: Measure 18 mL of glycerol into a beaker, put it into an oven and heat it at 80 °C for 15 min. After it cools to room temperature, perform a water bath stirring at 100 °C for 10 min again. Weigh 0.485 g of Bi(NO 3 )·5H2O and put it into a beaker, and perform magnetic stirring for 10 min. Weigh 0.05844 g of NaCl and perform magnetic stirring for another 20 min. Put the obtained solution into a polytetrafluoroethylene autoclave, heat it at 160 °C for 24 h. After cooling to room temperature, centrifuge to collect the precipitate and wash it several times with ethanol and water. Vacuum-dry the obtained product at 60 °C overnight. Put the obtained product into a muffle furnace and heat it at a heating rate of 3 °C / min. The final temperature is maintained at 450 °C for 2 h. After it cools to room temperature, grind it to obtain BiOCl / Bi 24 O 31 Cl 10 , and the product yield is 0.1907 g. After measurement, the mass ratio of BiOCl to Bi 24 O 31 Cl 10 is about 1:2; BiOCl / Bi 24 O 31 Cl 10The mass fraction of BiOCl in the composite product is 32.3%, and the mass fraction of Bi 24 O 31 Cl 10 is 67.7%.

[0051] Example 2

[0052] In this example, BiOCl / Bi 24 O 31 Cl 10 / TiO 2 composite material was prepared. The specific process is as follows:

[0053] Preparation of TiO 2 by hydrothermal method: First, 4 mL of deionized water was sucked into a beaker, and then 0.24 mL of concentrated sulfuric acid with a concentration of 98% was slowly added thereto, and then 4 mL of tetrabutyl titanate and 60 mL of absolute ethanol were added in sequence. The resulting solution was stirred for 30 min. After the stirring was completed, it was poured into a high-pressure autoclave with a polytetrafluoroethylene inner liner and heated at 180 °C for 4 h. After cooling to room temperature, the precipitate was collected by centrifugation, and the precipitate was washed with deionized water and absolute ethanol, dried overnight, and the collected product was ground for standby.

[0054] Preparation of BiOCl / Bi 24 O 31 Cl 10 / TiO 2 by hydrothermal method: 18 mL of glycerol was measured into a beaker, and it was placed in an oven and heated at 80 °C for 15 min. After cooling to room temperature, it was stirred in a water bath at 100 °C for 10 min. 0.485 g of Bi(NO 3 )·5H 2 O was weighed and placed in a beaker, and magnetic stirring was carried out for 10 min. After the stirring was completed, 0.05844 g of NaCl was weighed again, and magnetic stirring was carried out for 20 min. 0.08 g of TiO 2 prepared by hydrothermal method was weighed, and magnetic stirring was carried out for 10 min. The resulting solution was placed in a polytetrafluoroethylene high-pressure autoclave and heated at 160 °C for 24 h. After cooling to room temperature, the precipitate was collected by centrifugation and washed several times with ethanol and water. The resulting product was vacuum dried at 60 °C overnight. The obtained product was placed in a muffle furnace and heated at a heating rate of 3 °C / min, and the final temperature was maintained at 450 °C for 2 h. After cooling to room temperature, it was ground to obtain BiOCl / Bi 24 O 31 Cl 10 / TiO 2 .

[0055] Example 3

[0056] In this example, an electrode was prepared. The specific process was as follows:

[0057] Disperse the BiOCl / Bi prepared in Example 1 24 O 31 Cl 10 , the TiO prepared in Example 2 2 , BiOCl / Bi 24 O 31 Cl 10 / TiO 2 separately in deionized water, and disperse them evenly by ultrasonic treatment to obtain a stable suspension with a concentration of 3 mg / mL. Pipette 80 μL of the formed suspension onto FTO (1.5×2.5 cm, the actual effective area is 0.0706 cm 2 ) and let it dry naturally to obtain the corresponding electrode.

[0058] Example 4

[0059] In this example, an electrode was prepared. The specific process was as follows:

[0060] Place the air-dried BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode in an acetic acid-sodium acetate buffer solution (pH = 5.2) containing cefquinome sulfate (5 mmol / L) and o-phenylenediamine (15 mmol / L), and perform electro-polymerization by cyclic voltammetry. The potential range is 0 - 0.8 V, the scan rate is 50 mV / s, and cyclic voltammetry is carried out for 15 cycles to obtain the MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode. Let it dry.

[0061] Place the air-dried MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode in a solution of methanol: acetic acid (V:V = 9:1) for elution for 20 min. Then wash it with deionized water to obtain the rMIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode, and let it dry.

[0062] Comparative Example 1

[0063] This comparative example prepared a non-molecularly imprinted electrode, which was different from Example 4 in that cefquinome sulfate was not added. The specific preparation process referred to Example 4.

[0064] Test Example 1

[0065] In this test example, the electrodes prepared in Example 3, Example 4, and Comparative Example 1 were respectively subjected to cyclic voltammetry experiments with a voltage range of -0.2 V to 0.6 V, and the detection solution was 5 mM [Fe(CN)6] 3- / 4- and 0.1 M KCl solution. The results are as Figure 2 shown, where (a): TiO 2 ; (b) BiOCl / Bi 24 O 31 Cl 10 ; (c) BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (d) MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (e) MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 ; (f) The MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 was incubated in a 0.25 mg / mL cefquinome solution for 25 min..

[0066] It can be seen from Figure 2 that when the current value of the MIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode obtained by electro-polymerization through cyclic voltammetry in the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode becomes smaller, and when this electrode is placed in the eluent for elution, its current value becomes larger again.

[0067] This test example also performed impedance tests on the above electrodes. The specific process was as follows:

[0068] Different electrodes were placed in 5 mM [Fe(CN)6] 3- / 4-Impedance tests were carried out on solutions of 0.1 M KCl, and the measurement frequency parameter of EIS was 0.1 Hz to 100 kHz. The results are as Figure 3 shown.

[0069] From Figure 3 it can be seen that for the composite materials of TiO 2 , BiOCl / Bi 24 O 31 Cl 10 , BiOCl / Bi 24 O 31 Cl 10 / TiO 2 , the polymerized BiOCl / Bi 24 O 31 Cl 10 / TiO 2 , the eluted BiOCl / Bi 24 O 31 Cl 10 / TiO 2 and the BiOCl / Bi 24 O 31 Cl 10 / TiO 2 electrodes after re-incubation, it can be seen that the resistance of the final composite material is the smallest, and the resistance of the electrode after polymerization is the largest. Figure 3 The resistance result is Figure 2 opposite to the current results obtained from the CV cycle experiments of the respective materials in

[0070] Example 5

[0071] In this example, cefquinome was detected. The specific process was as follows:

[0072] The rMIP / BiOCl / Bi 24 O 31 Cl 10 / TiO 2 / FTO electrode was incubated in cefquinome solutions of different concentrations (the concentrations were 5×10 -4 ; 5×10 -5 ; 3×10 -5 ; 5×10 -6 ; 3×10 -6 ; 5×10 -7 ; 5×10 -8 ; 3×10 -8 mol / L.) for 25 min, and then square wave voltammetry tests were carried out. The tests were carried out in the voltage range of -0.2 V - 0.6 V, and the test solution was 5 mM of [Fe(CN)6]3- / 4- and 0.1 M KCl. The results are as Figure 4 , Figure 5 shown.

[0073] It can be seen from Figure 4 that its peak current gradually decreases with the increase of concentration. The detection range of the prepared electrode is 5×10 -4 ~3×10 -8 mol / L. Figure 5 is obtained by fitting the linear relationship of the peak current obtained from Figure 4 . It can be seen from Figure 5 that the linear equation is I = -0.045lgc + 0.847, R 2 = 0.995.

[0074] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent substitution methods and are all included in the protection scope of the present invention.

Claims

1. An electrochemical sensor electrode, characterized in that: The invention comprises a conductive substrate and BiOCl / Bi loaded on the conductive substrate. 24 O 31 Cl 10 / TiO2 composite materials.

2. The electrochemical sensor electrode according to claim 1, characterized in that: The BiOCl / Bi 24 O 31 Cl 10 The deposition amount of / TiO2 composite material is 1~6mg / cm 2 .

3. The electrochemical sensor electrode according to claim 1, characterized in that: The BiOCl / Bi 24 O 31 Cl 10 In the BiOCl / Bi / TiO2 composite materials, 24 O 31 Cl 10 The molar ratio to TiO2 is 1:(1~2).

4. The electrochemical sensor electrode according to claim 1, characterized in that: The conductive substrate includes any one of a metal substrate, a carbon material substrate and a conductive glass substrate.

5. A method for preparing an electrochemical sensor electrode according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Place TiO2 in a mixed solution of bismuth salt and chloride salt, perform hydrothermal reaction and then calcine to obtain BiOCl / Bi 24 O 31 Cl 10 / TiO2 composite materials; S2: BiOCl / Bi 24 O 31 Cl 10 The / TiO2 composite material solution is coated on a conductive substrate to obtain the electrochemical sensor electrode.

6. A molecular imprinting-based electrochemical sensor, characterized in that: The electrochemical sensor electrode comprises the electrochemical sensor electrode according to any one of claims 1 to 4.

7. The molecular imprinting-based electrochemical sensor according to claim 6, characterized in that: The surface of the electrochemical sensor electrode is also modified with a molecular imprinting polymer; the molecular imprinting polymer is formed by a template molecule 7-aminocephalosporanic acid and a functional monomer.

8. A method for detecting 7-aminocephalosporanic acid, comprising the following steps: The electrochemical sensor electrode according to any one of claims 1 to 4 or the molecular imprinting-based electrochemical sensor according to claim 6 is incubated with 7-aminocephalosporanic acid, and the current is tested by voltammetry to obtain the concentration of 7-aminocephalosporanic acid.

9. Use of the electrochemical sensor electrode according to any one of claims 1 to 4 or the molecular imprinting-based electrochemical sensor according to claim 6 in detecting 7-aminocephalosporanic acid.

10. The use according to claim 9, characterized in that: The 7-aminocephalosporin acid includes at least one of cephalexin, cephradine, cefdinir, cefpirin, cefixime, cefazolin, cefpirome, cefquinome and cefoperazone.

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