Photoelectrochemical sensor, preparation method and application

Abstract

The invention provides a photoelectrochemical sensor as well as a preparation method and application thereof, and the photoelectrochemical sensor is obtained by electrically polymerizing a molecularly imprinted polymer on a BiVO4 / CuO-FTO electrode by taking pyrrole as a functional monomer and oxytetracycline as a template molecule on the basis of the BiVO4 / CuO-FTO electrode. The method comprises the following steps: constructing a three-electrode system by using a photoelectrochemical sensor, forming standard mixed solutions containing different oxytetracycline concentrations by using oxytetracycline and a buffer solution, carrying out photocurrent test to obtain standard photoelectric signals of different oxytetracycline concentrations, drawing by using the oxytetracycline concentrations as horizontal coordinates and the standard photoelectric signals as vertical coordinates to obtain a standard curve, and calculating the oxytetracycline concentration. A milk sample containing oxytetracycline is subjected to the photocurrent test operation to obtain a photoelectric signal, and the photoelectric signal is substituted into the standard curve to obtain the content of oxytetracycline in the sample solution to be tested. The invention has the advantages of small size, simple operation, simple preparation, low cost, good specific selectivity and huge application prospect.

Description

Technical Field

[0001] The present invention relates to the field of analysis and detection, and in particular to a photoelectrochemical sensor, a preparation method and an application thereof. Background Art

[0002] Nowadays, milk has become an important part of people's daily diet. The protein in milk is beneficial to muscle strength and physical recovery, and is beneficial to human health. As the first generation of natural tetracycline antibiotics, oxytetracycline has a good inhibitory effect on Gram-negative and Gram-positive bacteria, so it has important clinical significance in livestock and poultry farming. Oxytetracycline is also widely used in cattle farms to treat beef cattle diseases and dairy cow diseases. Studies have shown that oxytetracycline takes a long time to be eliminated in animals and is easily combined with proteins and other nutrients in milk. Therefore, after the drug is used in milk, its residues may enter the milk along with the milk. Such residues may not only affect the quality of milk, but also have adverse effects on human health. In order to ensure the safety of milk, all countries have stipulated the maximum residue limit of oxytetracycline in milk. Therefore, it is particularly important to carry out research on the residual analysis method of oxytetracycline in milk. Through accurate and reliable analysis methods, oxytetracycline residues in milk can be detected and controlled in time to ensure the quality of milk and the health of consumers.

[0003] Although various oxytetracycline detection methods have been developed, such as gas chromatography-mass spectrometry, thin-layer chromatography, high-performance liquid chromatography-mass spectrometry, and enzyme-linked immunosorbent assay, these methods all have some disadvantages, such as expensive equipment, complicated operation, and cumbersome pretreatment. In view of the harm of oxytetracycline residues in milk to human health, it is necessary to develop a simple, accurate, rapid, and low-cost detection method. Compared with traditional electrochemical sensors, photoelectrochemical sensors have the advantages of low background current. In addition, they have the advantages of simple instrumentation, low cost, easy operation, and high sensitivity, and have attracted much attention.

[0004] However, photoelectric sensors also have the disadvantages of poor anti-interference ability and low specific recognition ability for targets. Traditional molecular imprinting sensors have the advantages of high specific recognition ability and good stability, but also have the problem of poor sensitivity. Summary of the invention

[0005] In view of the above situation, the main purpose of the present invention is to propose a photoelectrochemical sensor, a preparation method and an application to solve the above technical problems.

[0006] The present invention provides a method for preparing a photoelectrochemical sensor, the method is used to prepare the above-mentioned photoelectrochemical sensor, the method comprises the following steps: BiVO 4 / The non-modified part of the conductive surface of the CuO-FTO electrode is covered with an insulating layer to obtain a BiVO4 / CuO-FTO working electrode; Oxytetracycline and pyrrole functional monomers were electropolymerized onto the BiVO4 / CuO-FTO working electrode to obtain the MIP-BiVO4 / CuO-FTO electrode. MIP-BiVO 4 / The oxytetracycline in the CuO-FTO electrode was eluted to obtain a photoelectrochemical sensor.

[0007] The present invention also provides a photoelectrochemical sensor, which is obtained by electropolymerizing a molecular imprinting polymer on a BiVO4 / CuO-FTO electrode using pyrrole as a functional monomer and oxytetracycline as a template molecule. The present invention also provides an application of a photoelectrochemical sensor, wherein the photoelectrochemical sensor is prepared by the above-mentioned preparation method of a photoelectrochemical sensor, and the photoelectrochemical sensor is used for detecting the content of oxytetracycline in milk.

[0008] The present invention also provides a method for detecting oxytetracycline content in milk based on a photoelectric chemical sensor, the method specifically comprising the following steps: Based on the three-electrode system, the photoelectrochemical sensor was used as the working electrode, the Ag / AgCl electrode was used as the reference electrode, and the platinum wire was used as the counter electrode; A standard mixed solution consisting of oxytetracycline and Na2EDTA buffer was used as the electrolyte; The photocurrent of the electrolyte was tested, and the photocurrent measured by the electrolyte without oxytetracycline was used as a comparison, and the difference between the two was used as the standard photoelectric signal; The photocurrent test operation is repeated by changing the concentration of oxytetracycline in the electrolyte, and the measured result each time is compared with the photocurrent measured by the electrolyte without oxytetracycline, and the standard photoelectric signals of different oxytetracycline concentrations are obtained by testing; The standard curve was obtained by plotting the concentration of oxytetracycline as the horizontal axis and the standard photoelectric signal as the vertical axis; Take the milk sample solution containing oxytetracycline and mix it with Na2EDTA buffer to form an electrolyte for photocurrent test operation to obtain a photoelectric signal. Substitute the photoelectric signal into the standard curve to obtain the oxytetracycline content in the sample solution to be tested.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The method provided by the present invention has good specific selectivity for oxytetracycline detection; 2. The method provided by the present invention is easy to operate, simple to prepare, low in cost, does not require the operation of specific professionals, and has great application prospects in the field of rapid on-site detection.

[0010] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description or learned through embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the construction method of the photoelectrochemical molecular imprinting sensor of the present invention; Figure 2 The change in photoelectric current of the photoelectrochemical sensor constructed in Example 2 of the present invention after being placed for 7 days.

[0012] Figure 3 Photoelectric signals corresponding to different oxytetracycline concentrations of Example 5 of the present invention (ai: 0.1, 1, 10, 100, 1000 nmol / L); Figure 4 The standard curve diagram of the relationship between the logarithm of the oxytetracycline concentration and the photoelectric signal of Example 5 of the present invention (the concentration of oxytetracycline is in the range of 0.1-1000 nmol / L); Figure 5 The photoelectric signals corresponding to different oxytetracycline concentrations of Example 6 of the present invention (0.01, 0.1, 1, 10, 100, 1000 nmol / L); Figure 6 The standard curve diagram of the relationship between the logarithm of the oxytetracycline concentration and the photoelectric signal of Example 6 of the present invention (the concentration of oxytetracycline is in the range of 0.01-1000 nmol / L); Figure 7 The standard curve diagram of the relationship between the logarithm of the oxytetracycline concentration and the photoelectric signal of Example 7 of the present invention (the concentration of oxytetracycline is in the range of 0.02-5 mmol / L); Figure 8 The photoelectric signal responses of the photoelectric chemical sensor of Example 4 of the present invention to oxytetracycline, chloramphenicol, erythromycin, and tetracycline hydrochloride are shown. DETAILED DESCRIPTION

[0013] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0014] These and other aspects of the embodiments of the present invention will be apparent with reference to the following description and accompanying drawings. In these descriptions and accompanying drawings, some specific implementations of the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0015] Example 1 This embodiment discloses a photoelectrochemical sensor, which is obtained by electropolymerizing a molecular imprinting polymer on a BiVO4 / CuO-FTO electrode using pyrrole as a functional monomer and oxytetracycline as a template molecule.

[0016] Example 2 See also Figure 1 This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps: Step 1. Grind BiVO4 / CuO into fine powder, take 40 mg of ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 40 μL of NafionD-521 solution in a centrifuge tube, and ultrasonicate for 20 min.

[0017] The mixture was placed in a centrifuge tube and shaken. Take the FTO glass and tape its surface until the remaining area is 1 cm × 1 cm, then put it into the centrifuge tube and centrifuge it 4 times to allow BiVO4 / CuO to be deposited on the FTO. After drying, the non-modified part of the conductive surface (except for the area of ​​1 cm × 1 cm) is covered with an insulating layer. In this embodiment, the insulating layer is nail polish. After natural air drying, the BiVO4 / CuO-FTO working electrode can be obtained.

[0018] Using pyrrole (OPD) as a functional monomer and oxytetracycline (OTC) as a template molecule, molecular imprinting polymer was electropolymerized on BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry (CV) in an acetate buffer containing 0.6 mM pyrrole and 0.2 mM OTC at pH = 7, with a voltage range of 0.6 v, a scan speed of 50 mv / s, and 30 cycles. The electrode was slowly rinsed with distilled water and dried, thereby obtaining a MIP-BiVO4 / CuO-FTO electrode.

[0019] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), the constant voltage was set to +0.9 v, eluted for 10 min, and then repeatedly washed with deionized water to obtain a photoelectrochemical sensor, recorded as rMIP-BiVO4 / CuO-FTO electrode.

[0020] Example 3 This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps: Step 1. Grind BiVO4 / CuO into fine powder, take 50 mg of the ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 45 μL of NafionD-521 solution in a centrifuge tube, and ultrasonicate for 20 min.

[0021] The mixture was placed in a centrifuge tube and shaken. Take the FTO glass and tape its surface until the remaining area is 1 cm×1 cm, then put it into the centrifuge tube and centrifuge it 5 times to allow BiVO4 / CuO to be deposited on the FTO. After drying, the non-modified part of the conductive surface (except for the area of ​​1 cm×1 cm) is covered with an insulating layer. In this embodiment, the insulating layer is nail polish. After natural air drying, the BiVO4 / CuO-FTO working electrode can be obtained.

[0022] Using pyrrole as a functional monomer and oxytetracycline as a template molecule, molecular imprinting polymer was electropolymerized on the BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry, in an acetate buffer containing 0.7 mM pyrrole and 0.3 mM OTC at pH = 7, with a voltage range of 0.8 v, a scan speed of 50 mv / s, and 40 cycles, and then slowly rinsed with distilled water and dried, thereby obtaining a MIP-BiVO4 / CuO-FTO electrode.

[0023] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), the constant voltage was set to +0.9 v, eluted for 10 min, and then repeatedly washed with deionized water to obtain a photoelectrochemical sensor, recorded as rMIP-BiVO4 / CuO-FTO electrode.

[0024] Example 4 This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps: Step 1. Grind BiVO4 / CuO into fine powder, take 20 mg of the ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 40 μL of NafionD-521 solution in a centrifuge tube, and ultrasonicate for 20 min.

[0025] The mixture was placed in a centrifuge tube and shaken. Take the FTO glass and tape its surface until the remaining area is 1 cm×1 cm, then put it into the centrifuge tube and centrifuge it 4 times to allow BiVO4 / CuO to be deposited on the FTO. After drying, the non-modified part of the conductive surface (except for the area of ​​1 cm×1 cm) is covered with an insulating layer. In this embodiment, the insulating layer is nail polish. After natural air drying, the BiVO4 / CuO-FTO working electrode can be obtained.

[0026] Using pyrrole as a functional monomer and oxytetracycline as a template molecule, molecular imprinting polymer was electropolymerized on the BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry, in an acetate buffer containing 0.3 mM pyrrole and 0.1 mM oxytetracycline at pH = 7, with a voltage range of 0.2 v, a scan speed of 50 mv / s, and 15 cycles. The electrode was slowly rinsed with distilled water and dried, thereby obtaining a MIP-BiVO4 / CuO-FTO electrode.

[0027] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), the constant voltage was set to +0.9 v, eluted for 10 min, and then repeatedly washed with deionized water to obtain a photoelectrochemical sensor, recorded as rMIP-BiVO4 / CuO-FTO electrode.

[0028] Example 5 This embodiment discloses an application of a photoelectrochemical sensor, a photoelectrochemical sensor prepared by the above-mentioned preparation method of a photoelectrochemical sensor, the photoelectrochemical sensor is used to detect the content of oxytetracycline in milk, and the method for detecting the content of oxytetracycline in milk using the photoelectrochemical sensor specifically comprises the following steps: Step 1: A typical three-electrode system was used, with the Ag / AgCl electrode used as the reference electrode, the platinum wire used as the counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 2 as the working electrode. A 70 W metal halide lamp was used as the light source to illuminate the three-electrode system. The photocurrent was measured in alternating cycles of 20 s light and 20 s dark. After the test sensor was prepared and stored for seven days, the photocurrent response was obtained by turning the light on and off every 20 s for 1000 s. Figure 2 , it can be observed that the sensor has high stability.

[0029] Step 2: Use a standard mixed solution consisting of 2 mL of oxytetracycline aqueous solution and 8 mL of Na2EDTA buffer as the electrolyte to test the photocurrent. The photocurrent measured by the electrolyte without oxytetracycline is used as a comparison, and the difference between the two is used as the photoelectric signal (ΔI); Step 3: Change the concentration of oxytetracycline in the electrolyte to 0.1, 1, 10, 100, and 1000 nmol / L respectively. Repeat step 1 and test to obtain the following results: Figure 3 , photoelectric signal of the sensor of standard solution of oxytetracycline with different concentrations; Step 4: Plot the concentration of oxytetracycline as the horizontal axis and the photoelectric signal as the vertical axis to obtain the following: Figure 4 The standard curve shown is ΔI=0.85687logC+ 1.1669 (nmol / L), and the corresponding correlation coefficient (R2 ) is 0.99022; Step 5. Take 2 mL of milk sample obtained from the local market and place it in a beaker. Add 8 mL of Na2EDTA buffer and mix by ultrasound. Centrifuge the mixture twice at 4500 rpm for 15 min each time and filter it three times with a 0.45 μm ultrafiltration membrane. Add 0.20 mmol / L oxytetracycline to the filtrate and repeat the test in step 1. The measured photoelectric signal is brought into the standard curve to calculate the oxytetracycline concentration of 0.21 and the recovery rate is 105%.

[0030] Example 6 This embodiment discloses an application of a photoelectrochemical sensor, a photoelectrochemical sensor prepared by the above-mentioned method for preparing a photoelectrochemical sensor, the photoelectrochemical sensor is used to detect the content of oxytetracycline in milk, and the method for detecting the content of oxytetracycline in milk using the photoelectrochemical sensor specifically comprises the following steps: Step 1: A typical three-electrode system was used, with an Ag / AgCl electrode as a reference electrode, a platinum wire as a counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 3 as a working electrode. A 70 W metal halide lamp was used as a light source to illuminate the three-electrode system. The photocurrent was measured in an alternating cycle of 20 s illumination and 20 s darkness.

[0031] Step 2: Use a standard mixed solution consisting of 3 mL of oxytetracycline aqueous solution and 7 mL of Na2EDTA buffer as the electrolyte to test the photocurrent. The photocurrent measured by the electrolyte without oxytetracycline is used as a comparison, and the difference between the two is used as the photoelectric signal (ΔI); Step 3: Change the concentration of oxytetracycline in the electrolyte to 0.01, 0.1, 1, 10, 100, 1000 nmol / L respectively. Repeat step 3 and test to obtain the following results: Figure 5 , photoelectric signal of the sensor of standard solution of oxytetracycline with different concentrations; Step 4: Plot the concentration of oxytetracycline as the horizontal axis and the photoelectric signal as the vertical axis to obtain the following: Figure 6 The standard curve shown (ΔI=1.22512logC+3.64641, correlation coefficient R 2 =0.9909); Step 5. Take 3 mL of milk sample obtained from the local market and place it in a beaker. Add 7 mL of Na2EDTA buffer and mix by ultrasound. Centrifuge the mixture twice at 4500 rpm for 15 min each time and filter it three times with a 0.45 μm ultrafiltration membrane. Add 0.50 mmol / L oxytetracycline to the filtrate and repeat the test in step 3. The measured photoelectric signal is brought into the standard curve to calculate the oxytetracycline concentration of 0.49 and the recovery rate of 98%.

[0032] Example 7 This embodiment discloses an application of a photoelectrochemical sensor, a photoelectrochemical sensor prepared by the above-mentioned method for preparing a photoelectrochemical sensor, the photoelectrochemical sensor is used to detect the content of oxytetracycline in milk, and the method for detecting the content of oxytetracycline in milk using the photoelectrochemical sensor specifically comprises the following steps: Step 1: A typical three-electrode system was used, with an Ag / AgCl electrode as a reference electrode, a platinum wire as a counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 4 as a working electrode. A 70 W metal halide lamp was used as a light source to illuminate the three-electrode system. The photocurrent was measured in an alternating cycle of 20 s illumination and 20 s darkness.

[0033] Step 2: Use a standard mixed solution consisting of 1 mL of oxytetracycline aqueous solution and 9 mL of Na2EDTA buffer as the electrolyte to test the photocurrent. The photocurrent measured by the electrolyte without oxytetracycline is used as a comparison, and the difference between the two is used as the photoelectric signal (ΔI); Step 3, changing the concentration of oxytetracycline in the electrolyte to make its concentration 0.02, 0.04, 0.10, 0.6, 1, 5 mmol / L respectively, repeating step 1, and testing to obtain the photoelectric signal of the sensor of the standard solution of different concentrations of oxytetracycline; Step 4: Plot the concentration of oxytetracycline as the horizontal axis and the photoelectric signal as the vertical axis to obtain the following: Figure 7 The standard curve shown (ΔI = 0.65353 logC + 1.1042, R 2 =0.99394); Step 5. Take 1 mL of milk sample obtained from the local market and place it in a beaker. Add 9 mL of Na2EDTA buffer and mix ultrasonically. Centrifuge the mixture twice at 4500 rpm for 15 min each time, and filter it three times with a 0.45 μm ultrafiltration membrane. Add 1 mmol / L oxytetracycline to the filtrate, repeat the test in step 1, and the measured photoelectric signal is brought into the standard curve to calculate the oxytetracycline concentration of 0.97, with a recovery rate of 97%. In order to investigate the specific recognition ability of the constructed sensor for oxytetracycline. The photoelectric signals of four milk samples containing the same concentration (0.6 mmol / L) of oxytetracycline, tetracycline hydrochloride, erythromycin, and chloramphenicol were determined using the same determination procedure, as shown in the figure. Figure 8 As shown, it can be seen that the constructed photoelectrochemical molecular imprinting sensor has a good recognition ability for oxytetracycline.

[0034] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0036] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a photoelectrochemical sensor, characterized in that: The method comprises the following steps: The non-modified portion of the conductive surface of the BiVO4 / CuO-FTO electrode is covered with an insulating layer to obtain a BiVO4 / CuO-FTO working electrode; Oxytetracycline and pyrrole functional monomers were electropolymerized onto the BiVO4 / CuO-FTO working electrode to obtain the MIP-BiVO4 / CuO-FTO electrode. The oxytetracycline in the MIP-BiVO4 / CuO-FTO electrode was washed away to obtain a photoelectrochemical sensor.

2. The method for preparing a photoelectrochemical sensor according to claim 1, characterized in that: The method of electropolymerizing oxytetracycline and pyrrole functional monomers onto the BiVO4 / CuO-FTO working electrode to obtain the MIP-BiVO4 / CuO-FTO electrode specifically includes the following steps: By cyclic voltammetry, an acetate buffer solution of pH 7 containing 0.3-0.6 mM pyrrole and 0.1-0.2 mM oxytetracycline was prepared, and the BiVO4 / CuO-FTO working electrode was placed in the acetate buffer solution. The voltage range was set to 0.2-0.6 V, the scanning speed was 50 mv / s, the number of cycles was 15-30 times, and the electrode was slowly rinsed with distilled water and dried to obtain a MIP-BiVO4 / CuO-FTO electrode.

3. The method for preparing a photoelectrochemical sensor according to claim 2, characterized in that: The method for eluting oxytetracycline from the MIP-BiVO4 / CuO-FTO electrode to obtain a photoelectrochemical sensor specifically comprises the following steps: The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution, pH of PBS buffer solution was 7.4, the constant voltage was set to +0.9 V, eluted for 10 min, and then repeatedly washed with deionized water to obtain a photoelectrochemical sensor.

4. The method for preparing a photoelectrochemical sensor according to claim 3, characterized in that: The preparation method of BiVO4 / CuO-FTO electrode specifically includes the following steps: The BiVO4 / CuO was ground into fine powder, mixed with isopropyl alcohol and Nafion D-521 solution, and then the mixture was deposited on a FTO conductive glass sheet by centrifugation to form a BiVO4 / CuO-FTO electrode.

5. A photoelectrochemical sensor, characterized in that: The photoelectrochemical sensor is prepared using the preparation method of the photoelectrochemical sensor as described in any one of claims 1 to 4. The photoelectrochemical sensor is obtained by electropolymerizing a molecular imprinting polymer on a BiVO4 / CuO-FTO electrode using pyrrole as a functional monomer and oxytetracycline as a template molecule.

6. An application of a photoelectrochemical sensor, wherein the photoelectrochemical sensor is prepared by the preparation method of a photoelectrochemical sensor according to any one of claims 1 to 4, and the photoelectrochemical sensor is used for detecting the content of oxytetracycline in milk.

7. The use of a photoelectrochemical sensor according to claim 6, characterized in that: The method for detecting the content of oxytetracycline in milk using a photoelectric chemical sensor specifically comprises the following steps: Based on the three-electrode system, the photoelectrochemical sensor was used as the working electrode, the Ag / AgCl electrode was used as the reference electrode, and the platinum wire was used as the counter electrode; A standard mixed solution consisting of oxytetracycline and Na2EDTA buffer was used as the electrolyte; The photocurrent of the electrolyte was tested, and the photocurrent measured by the electrolyte without oxytetracycline was used as a comparison, and the difference between the two was used as the standard photoelectric signal; The photocurrent test operation is repeated by changing the concentration of oxytetracycline in the electrolyte, and the measured result each time is compared with the photocurrent measured by the electrolyte without oxytetracycline, and the standard photoelectric signals of different oxytetracycline concentrations are obtained by testing; The standard curve was obtained by plotting the concentration of oxytetracycline as the horizontal axis and the standard photoelectric signal as the vertical axis; Take the milk sample solution containing oxytetracycline and mix it with Na2EDTA buffer to form an electrolyte for photocurrent test operation to obtain a photoelectric signal. Substitute the photoelectric signal into the standard curve to obtain the oxytetracycline content in the sample solution to be tested.

8. The use of a photoelectrochemical sensor according to claim 7, characterized in that: In the photocurrent test, a 70 W halogen lamp was used as the light source to illuminate the three electrodes. The test was performed under no bias voltage conditions, with each illumination period of 20 s and light shielding period of 20 s.

9. The use of a photoelectrochemical sensor according to claim 8, characterized in that: The milk sample solution containing oxytetracycline to be tested is a milk sample obtained from the market, Na2EDTA buffer is added, ultrasonic mixing is performed, and the supernatant is obtained by centrifugation, which is then filtered three times with a 0.45 μm ultrafiltration membrane, and finally different concentrations of standard oxytetracycline samples are added to obtain the supernatant.

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