Photoelectric chemical sensor for detecting chloramphenicol and preparation method thereof

Abstract

The present invention discloses a photoelectrochemical sensor for detecting chloramphenicol and a preparation method thereof, belonging to the technical field of electrochemical sensors. The sensor comprises: a titanium substrate, titanium dioxide nanotubes formed by oxidation on the titanium substrate, a molecularly imprinted membrane modified on the surface of the titanium dioxide nanotubes, a counter electrode, and a reference electrode; the molecularly imprinted membrane is a chloramphenicol molecularly imprinted membrane formed by polymerizing chloramphenicol and aniline on a working electrode through an electrode reaction, after which the chloramphenicol is removed; the titanium dioxide nanotubes constitute the working electrode, and the molecularly imprinted membrane constitutes the working surface of the working electrode. The sensor device of the present invention has the characteristics of high sensitivity, rapid detection, and good stability in the detection of chloramphenicol. The principle of oxidizing the imprinted membrane by generating photogenerated holes under illumination is utilized, so that the device can self-clean and achieve the purpose of being used multiple times.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical sensors, and more particularly to a photoelectrochemical sensor for detecting chloramphenicol and a preparation method thereof. Background Art

[0002] Finding a rapid and accurate detection method to identify toxins in food is crucial. Chloramphenicol is a broad-spectrum, highly effective antibacterial drug that effectively controls Gram-negative bacterial infections, particularly Salmonella typhi and other Salmonella species. However, chloramphenicol has significant toxic side effects and can cause bone marrow suppression, aplastic anemia, hypoplasia, thrombocytopenia, and leukopenia in humans and animals. High levels of chloramphenicol, nitrofurans, quinolones, and other nitro-containing harmful substances are often detected in seafood from coastal cities. Therefore, establishing a convenient, sensitive, and accurate method for the determination of chloramphenicol is of great practical significance.

[0003] Electrochemical sensing offers advantages such as high sensitivity, compact size, good linearity, high recovery, and ease of integration. However, commercially available spray-coated or printed graphite electrodes suffer from poor sensitivity and stability, and their selectivity and reusability still require improvement. These shortcomings hinder their practical application. Currently, the molecularly imprinted polymer membrane electrodes used in common electrochemical detection of chloramphenicol still present numerous challenges, including complex preparation methods, reduced performance of the imprinted membrane after detection due to a reduction in specific cavities, and inconvenience in rapid deployment across a variety of testing environments. Summary of the Invention

[0004] To address the problem in existing molecular imprinting technology that repeated use leads to a decrease in holes and reduced performance, the present invention proposes a photoelectrochemical sensor device with TiO2 as the substrate for the working electrode, pure silver as the conductor, and a molecular imprinting membrane as the electrode working surface. The device has the characteristics of high sensitivity, rapid detection and good stability in the detection of chloramphenicol. The device uses light to generate photocurrent to oxidize the imprinting membrane and elute the template, thereby achieving the purpose of hole self-cleaning, allowing the device to be reused multiple times.

[0005] Another object of the present invention is to provide a method for preparing a photoelectrochemical sensor for detecting chloramphenicol, which has simple steps.

[0006] In order to achieve these objectives of the present invention, the present invention provides a photoelectrochemical sensor for detecting chloramphenicol, comprising:

[0007] Titanium substrate, titanium dioxide nanotubes formed by oxidation on the titanium substrate, molecular imprinted film modified on the surface of the titanium dioxide nanotubes, a counter electrode and a reference electrode;

[0008] The molecular imprinted membrane is a chloramphenicol molecular imprinted membrane formed by polymerizing chloramphenicol and aniline on a working electrode through electrode reaction and then removing chloramphenicol. The titanium dioxide nanotubes constitute the working electrode, and the molecular imprinted membrane constitutes the working surface of the working electrode.

[0009] Preferably, in the photoelectrochemical sensor for detecting chloramphenicol, after detecting chloramphenicol, visible light (ultraviolet light) is used to irradiate the working electrode so that the template of the molecular imprinting membrane is eluted and the detection capability is restored.

[0010] Preferably, in the photoelectrochemical sensor for detecting chloramphenicol, the preparation method of the molecular imprinted membrane is specifically as follows: in an acidic system of aniline and chloramphenicol, the titanium dioxide nanotubes are used as working electrodes, the graphite sheet is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. An electrochemical workstation is used to first set a constant potential polarization program with the following parameters: polarization potential: -1.5V, polarization time: 20s; then a cyclic voltammetry program is set with the following parameters: initial potential -0.2V, termination potential 0.9V, scan rate: 200mV / s, number of cycles: 10; the molecular imprinted membrane is polymerized on the surface of the titanium dioxide nanotubes; and the template is then removed by visible light (ultraviolet light) irradiation and positive potential polarization.

[0011] Preferably, in the photoelectrochemical sensor for detecting chloramphenicol, a polyimide film is provided on the surface of the titanium substrate, the surface of the polyimide film has a silver film generated by a silver mirror reaction, and the reference electrode and the wires connecting the electrodes are formed by carving or cutting the silver film.

[0012] Preferably, in the photoelectrochemical sensor for detecting chloramphenicol, the counter electrode is a graphene electrode obtained by laser induction of a polyimide film on the surface of a titanium substrate.

[0013] The present invention provides a method for preparing a photoelectrochemical sensor for detecting chloramphenicol, comprising:

[0014] S1: After attaching three layers of polyimide film to a titanium substrate, the film is cut and shaped to expose the working electrode position on the titanium substrate; titanium dioxide nanotubes are then prepared at the working electrode position by anodization; and molecularly imprinted films are polymerized on the surface of the titanium dioxide nanotubes through electrode reaction in an acidic system of aniline and chloramphenicol.

[0015] S2: removing the first polyimide film on the titanium substrate, forming a silver film on the surface of the second polyimide layer through a silver mirror reaction, carving or cutting the silver film into a reference electrode and silver wires connecting the electrodes, and exposing the third polyimide film;

[0016] S3: Laser-induced graphene electrode on the third polyimide film as the counter electrode.

[0017] Preferably, in the preparation method of the photoelectrochemical sensor for detecting chloramphenicol, the preparation method of the titanium dioxide nanotubes is specifically as follows:

[0018] Step 1: Clean the titanium metal surface to obtain a titanium substrate;

[0019] Step 2: Attach three layers of polyimide film to the surface of the titanium substrate and laser cut to expose the working electrode position;

[0020] Step 3: In an electrolyte containing ammonium fluoride and ethylene glycol, the titanium substrate is used as the anode and the graphite sheet is used as the cathode. A DC power supply is used to set the constant voltage parameters to 50V and the time to 1800s for anodization. Then, the substrate is rinsed with alcohol and blown dry. Finally, the substrate is placed in a tube furnace and the initial temperature is set to 25°C, the heating rate is 5°C / min, the holding temperature is 500°C, and the holding time is 2 hours. Annealing is performed in air, and TiO2 transforms from an amorphous phase to anatase phase. At this point, the exposed metallic titanium is anodized to prepare dense titanium dioxide nanotubes.

[0021] Preferably, in the method for preparing the photoelectrochemical sensor for detecting chloramphenicol, the method for preparing the molecularly imprinted membrane is specifically as follows:

[0022] In an acidic electrolyte system containing aniline and chloramphenicol, the titanium dioxide nanotubes are used as working electrodes, a graphite sheet is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode. An electrochemical workstation is used to first set a constant potential polarization program with the following parameters: polarization potential: -1.5V, polarization time: 20s; then a cyclic voltammetry program is set with the following parameters: initial potential: -0.2V, termination potential: 0.9V, scan rate: 200mV / s, and number of cycles: 10; the molecular imprinting film is polymerized on the surface of the titanium dioxide nanotubes; and then the chloramphenicol template is removed by ultraviolet irradiation and positive potential polarization.

[0023] Preferably, in the method for preparing the photoelectrochemical sensor for detecting chloramphenicol, the method for forming the silver film is specifically:

[0024] The surface of the second polyimide film is modified with potassium hydroxide to form potassium polycarbamate; after cleaning, AgNO3 solution is dripped on the surface of the second polyimide film to achieve the replacement of silver ions with potassium ions in potassium polycarbamate; after cleaning, alkaline glucose solution is dripped on the surface of the second polyimide film to finally form a dense silver film with good conductivity on the surface of the second polyimide film.

[0025] Preferably, in the preparation method of the photoelectrochemical sensor for detecting chloramphenicol, the preparation method of the counter electrode is specifically as follows:

[0026] An ultraviolet marking machine was used for marking. The laser parameters were a wavelength of 355 nm, a frequency of 70 kHz, a focal length of 9.1 cm, a marking rate range of 10-30 m / s, and a power of 20-30%. Graphene electrodes were obtained by laser induction.

[0027] The present invention has at least the following beneficial effects:

[0028] 1. Better conductivity. Compared to conventional sprayed or printed graphite electrodes, the present invention uses a surface silver film generated by a silver mirror reaction on the polyimide surface and uses laser cutting to shape the electrode wire. It has better conductivity and more sensitive detection effect, which is conducive to the rapid detection of low-concentration substances.

[0029] 2. Lower detection limit. Compared with conventional sprayed or printed graphite electrodes, the working electrode of the present invention utilizes a specific recognition membrane prepared using molecular imprinting technology. This membrane can specifically adsorb certain target substances, enabling the electrode to accurately identify and detect nitrobenzene antibiotics in complex solution environments. Therefore, its ability to detect chloramphenicol is stronger than that of conventional sensor electrodes.

[0030] 3. More stable performance. Compared with conventional sprayed or printed graphite electrodes, printed graphene working electrodes are prone to unstable contact with the substrate, leading to electrode shedding during detection and uneven detection curves. However, the TiO2 nanotubes grown on the titanium substrate of the present invention are dense and stable, and electrode material shedding is almost non-existent during normal detection, resulting in a smooth detection curve.

[0031] 4. It can be reused more often. Conventional molecular imprinting electrodes consume specific holes due to repeated detection, resulting in a gradual weakening of the detection capability. The present invention introduces photoelectric technology into the working electrode, breaking the problem that traditional molecular imprinting electrochemical sensors cannot be reused multiple times. Because the photoelectric TiO2 nanotubes have the characteristic of generating photocurrent through light, and the heterojunction structure formed by the TiO2 nanotubes and the molecular imprinting film enables the photogenerated current to have the ability to elute the template, so that the composite specific holes are separated again. This photoelectric self-cleaning function increases the number of detection times of the device. Therefore, its repeatability is better than that of conventional electrochemical sensors.

[0032] 5. Wider application range. In addition to meeting the outdoor rapid testing requirements of testing institutions, the sensor device of the present invention can also be used for testing seafood and other foods in ordinary households. It is easy to operate and the test results can be obtained quickly.

[0033] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is an outline diagram of a titanium metal substrate for a micro-device according to an embodiment of the present invention;

[0035] Figure 2 This is an engraving of a PI tape and a working electrode adhered to the surface of a titanium substrate of a micro-device according to an embodiment of the present invention;

[0036] Figure 3 This is a diagram of the TiO2 nanotube structure on the working surface of a micro-device according to an embodiment of the present invention;

[0037] Figure 4 Laser engraving pattern of the silver electrode lines and reference electrode of the three electrodes of the micro-device according to the embodiment of the present invention;

[0038] Figure 5 This is a diagram of the shape of the counter electrode for laser marking of a micro-device according to an embodiment of the present invention;

[0039] Figure 6 This is an overall design diagram of a micro-device according to an embodiment of the present invention;

[0040] Figure 7 A complete model diagram and actual product diagram of the micro-device according to an embodiment of the present invention;

[0041] Figure 8 This is a DPV curve diagram of a standard chloramphenicol solution detected by a micro-device according to an embodiment of the present invention;

[0042] Figure 9 A linear relationship diagram of the micro-device fitting according to an embodiment of the present invention;

[0043] Figure 10 is an anti-interference curve diagram of a micro-device according to an embodiment of the present invention;

[0044] Figure 11 This is a DPV curve diagram of the micro-device according to an embodiment of the present invention for detecting chloramphenicol in drinking water;

[0045] Figure 12 This is a DPV curve diagram of the micro-device in an embodiment of the present invention detecting chloramphenicol in eye drops;

[0046] Figure 13 In the present invention, K3[Fe(CN)6] is used as a probe reagent for the pore to detect changes in specific pores.

[0047] In the figure: 1-titanium sheet, 2-polyimide tape, 3-working electrode cutting outline, 4-TiO2 nanotubes, 5-silver mirror film, 6-electrode silver wire, 7-reference electrode, 8-graphene counter electrode, 9-conductive silver paste, 10-epoxy resin. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below with reference to examples so that those skilled in the art can implement the invention with reference to the description.

[0049] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0050] Example 1

[0051] like Figures 1 to 7 As shown, a photoelectrochemical sensor microdevice for detecting chloramphenicol specifically includes: a titanium substrate constructed of a metal titanium sheet 1, TiO2 nanotubes 4, a molecular imprinting membrane, a reference electrode 7, and a counter electrode 8.

[0052] A titanium sheet 1 is affixed with three layers of polyimide tape 2. Cutting forms a working electrode cutout 3, exposing the titanium metal. TiO2 nanotubes 4 are grown within the working electrode cutout 3 via anodic oxidation. These serve as the working electrode, and a molecularly imprinted membrane (MIM) is applied to the surface of the TiO2 nanotubes 4 to form the electrode working surface. A silver mirror film 5, or silver film, is formed on the surface of the polyimide tape 2 via a silver mirror reaction. The tape is then cut to form a silver lead 6 and a reference electrode 7. A graphene counter electrode 8 is also formed on the polyimide tape 2. Conductive silver paste 9 is used to connect the working electrode and the graphene counter electrode to the silver lead 6, and the film is then encapsulated with epoxy resin 10.

[0053] Preferably, in the figure, the working electrode is located in the middle of the titanium substrate, the reference electrode 7 is surrounded by the outside of the working electrode, and the counter electrode 8 is surrounded by the outside of the working electrode.

[0054] The specific preparation process of the microdevice is shown in Example 2 below.

[0055] Example 2

[0056] A method for preparing a photoelectrochemical sensor for detecting chloramphenicol comprises:

[0057] The device support substrate can be made of 99.99% pure titanium sheet with a thickness of 0.2mm. Figure 1 The shape of the TiO2 nanotubes is prepared by anodizing the top surface. The steps of making the nanotubes are as follows:

[0058] 1. Ultrasonic cleaning of titanium sheets in acetone, alcohol, and deionized water for 10 minutes each. Prepare hydrofluoric acid, nitric acid, and water in a volume ratio of 1:3:6, soak the titanium sheet in the solution for 15 seconds, chemically polish its surface, and then soak it in deionized water for 5 minutes and ultrasonically remove the acid.

[0059] 2. Three layers of polyimide tape (PI) were applied to the cleaned titanium sheet surface and the surface was marked with an ultraviolet laser marking machine (KF-UV5, Sundor, China). Figure 2 The laser parameters for shape cutting are wavelength 355 nm, frequency 70 kHz, focal length 9.1 cm, cutting rate 1 mm / s, power 50%. The tape is removed to expose the titanium metal at the bottom.

[0060] 3. Prepare 1.5mmol / L ammonium fluoride solution and ethylene glycol in a volume ratio of 1:49, and use this solution as the electrolyte, the titanium sheet as the anode, and the graphite sheet as the cathode. Use a DC power supply to set the constant voltage parameters to 50V and the time to 1800s for anodization. Then rinse with alcohol and blow dry. Finally, place it in a tube furnace and set the initial temperature to 25℃, the heating rate to 5℃ / min, the holding temperature to 500℃, the holding time to 2 hours, and anneal in air to transform TiO2 from an amorphous phase to anatase phase.

[0061] At this point, the exposed titanium metal is anodized to form dense TiO2 nanotubes. The location and morphology of the nanotubes are as follows: Figure 3 shown.

[0062] The TiO2 nanotubes prepared above are used as a substrate, and a molecular imprinting membrane capable of detecting chloramphenicol is further modified on the surface, the steps of which are as follows:

[0063] Prepare the imprinted membrane electropolymerization electrolyte, including 0.2mol / L aniline, 0.5mol / L hydrochloric acid, 0.5mol / L nitric acid, and 5μmol / L chloramphenicol; TiO2 nanotubes are used as working electrodes, graphite sheets are used as counter electrodes, and saturated calomel electrodes are selected as reference electrodes. Use an electrochemical workstation to first set up a constant potential polarization program with the parameters set to polarization potential: -1.5V, polarization time: 20s, in order to improve its conductivity; when setting up cyclic voltammetry, the parameters are set to: initial potential: -0.2V, termination potential: 0.9V, scan rate: 200mV / s, and number of cycles: 10 circles, in order to polymerize a layer of molecular imprinted membrane on the surface of the TiO2 nanotubes; use a 35W xenon lamp and positive potential polarization method to remove the chloramphenicol template and prepare a molecular imprinted membrane for measuring chloramphenicol.

[0064] Remove the first layer of polyimide tape on the surface of the titanium sheet and pre-treat the second layer of tape to make it a conductive silver wire. The main methods are:

[0065] In the first step, the polyimide surface was modified with potassium hydroxide (KOH) to form polycarbamate through an imide ring cleavage reaction. Specifically, a 4M KOH solution was dripped onto the PI surface and allowed to soak for 4 hours to achieve PI ring opening.

[0066] In the second step, the PI surface from the previous step was cleaned with deionized water, and then a 0.1M AgNO3 solution was prepared and dropped on the PI surface after ring opening, and immersed for 3 hours to achieve the replacement of silver ions with potassium ions in potassium polyurethane on the PI surface.

[0067] In the third step, the PI surface was cleaned with deionized water, and then a 0.5M glucose solution was prepared, and the pH value of the glucose solution was adjusted to 12 with a 1M KOH solution. The prepared alkaline glucose solution was dropped onto the surface and immersed for 15 minutes.

[0068] Finally, a dense and highly conductive silver mirror layer will be obtained on the PI surface.

[0069] After the prepared silver mirror is dried, Figure 4 The surface of the pattern shown is engraved to obtain the three-electrode silver wire and reference electrode of the sensor device. After engraving, all the excess parts near the silver mirror are removed. Because the detection of chloramphenicol needs to be detected at a negative potential, the silver electrode is unstable as a counter electrode. Therefore, the exposed third layer of PI is mainly used for the preparation of the counter electrode. Use a UV marking machine, according to Figure 5 The pattern was marked in a fill-in manner. Laser parameters were a wavelength of 355 nm, a frequency of 70 kHz, a focal length of 9.1 cm, a marking rate range of 10-30 ms, and a power of 20-30%. Due to sample variability, the rate and power were adjusted arbitrarily. The ultimate goal was to obtain a laser-induced graphene electrode with a resistance of approximately 50 Ω. This graphene electrode served as the counter electrode.

[0070] The overall configuration of the complete photoelectrochemical sensor microdevice is as follows Figure 6 As shown in the figure, the prepared graphene electrode and working electrode are connected to the silver electrode at adjacent locations using conductive silver paste. Epoxy resin is used to completely encapsulate the silver wires (including the conductive silver paste connection) to prevent corrosion or physical damage to the silver wires, which could lead to electrode instability.

[0071] The overall effect of the photoelectrochemical sensor microdevice preparation and the actual product photos are as follows Figure 7 shown.

[0072] Example 3

[0073] 1. Electrochemical Detection of Chloramphenicol Using Photoelectrochemical Sensor Microdevices

[0074] The fabricated sensor microdevice was connected to the gold fingers of the three-electrode system using flat alligator copper clips, corresponding to the reference electrode, counter electrode, and working electrode terminals of the electrochemical workstation. The electrolyte was a 0.2 mol / L KCl solution, with 1 mM potassium ferrocyanide added to enhance detection. Subsequently, starting from a blank, chloramphenicol solutions at concentrations of 10 ppb, 20 ppb, 30 ppb, 40 ppb, 50 ppb, 60 ppb, 70 ppb, 80 ppb, and 90 ppb were added dropwise to monitor the chloramphenicol's reaction behavior. Before testing, the electrode surface was irradiated with UV light. After a period of time, chloramphenicol was detected by differential pulse voltammetry (DPV). DPV parameters were set as follows: initial scan potential: -1 V, end potential: 0 V, potential increment: 0.004 V, amplitude: 0.05 V, pulse width: 0.05 s, pulse period: 0.5 s.

[0075] like Figure 8 As shown in the figure, when the electrolyte does not contain chloramphenicol, the DPV curve does not show any reduction peak. However, when the electrolyte contains chloramphenicol, the DPV curve shows an obvious reduction peak at a potential of -0.48V. This is because the entire detection process is mainly due to the reduction of the nitro group on the benzene ring of chloramphenicol, which makes a reduction peak appear at -0.48V representing the specific binding of the hole and chloramphenicol, indicating the presence of chloramphenicol in the solution. According to the peak current value, the linear relationship between the detection current and the added concentration is fitted as shown in the figure. Figure 9 , a good linear relationship of R=0.9802 was obtained, and the results showed that the sensor had good current response and sensitivity to chloramphenicol in solution.

[0076] 2. Sensor Microdevice Anti-interference Experiment

[0077] Selectivity or anti-interference is a key parameter of electrochemical electrodes and sensors. In order to explore the anti-interference performance of this microsensor to several common organic compounds in water environment at corresponding potentials, the effect of external interfering species on the detection of 10μM chloramphenicol was investigated by adding different organic solutions into the measuring solution. The electrochemical response was recorded by the It curve. Figure 10 As shown, the sensor's anti-interference ability to chloramphenicol was tested at a potential of -0.48V, where a represents the addition of chloramphenicol solution. After adding 10μM chloramphenicol solution, the sensor had a significant amperometric response to each 10μM chloramphenicol solution within a very short period of time. However, when other organic solutions, such as sodium citrate, glucose, methylene blue, glyphosate, and malachite green, were added, represented by bf, respectively, no significant current response was observed for the other chloramphenicol solutions added. This indicates that the sensor of the disclosed embodiment is able to resist high concentrations of interfering ions when detecting chloramphenicol. Therefore, it can be used as a highly selective photoelectric sensor for chloramphenicol detection.

[0078] 3. Blind Sample Testing

[0079] The ability of the designed electrochemical sensor microdevice to test samples in life is of great significance for practical applications. This time, the content of chloramphenicol in drinking water and eye drops was determined. Before analysis, the sample was filtered with a 0.22μm cellulose membrane to remove particles and sediments, and then diluted with a certain amount of electrolyte solution (0.2M KCl) and a small amount of potassium ferricyanide solution was added. By adding a certain volume of blind sample solution to the test solution, the appearance of the reduction peak of drinking water and eye drops was observed. According to the linear and concentration standards obtained by fitting the chloramphenicol standard solution at different concentrations, the results of the blind sample were compared with the detection standards of the device.

[0080] like Figure 11 and Figure 12 The following figure shows the DPV curves of drinking water and eye drops at specific volumes, demonstrating that drinking water falls below the device's minimum detection concentration, while eye drops exhibit a chloramphenicol reduction peak near -0.48V, indicating that the microdevice can detect chloramphenicol in real samples. Based on the sensor microdevice's detection criteria for standard samples, the chloramphenicol concentrations for drinking water and eye drops were calculated by fitting: 0 ppm and 1.1 ppm, respectively. These results demonstrate the practicality and reliability of the developed sensor system.

[0081] 4. Detection of specific pore changes

[0082] In the present application, along with the continuous irradiation of visible light, TiO2 substrate will produce multiple photogenerated electrons and photogenerated holes, wherein the holes will spontaneously move to one side of the molecular imprinted film, and the molecular imprinted film will be oxidized to achieve the effect of removing the template molecule. When the electrode is irradiated, the photoelectric heterojunction consisting of TiO2 and the molecular imprinted film will promote the spontaneous movement of photogenerated electrons to the inside of the substrate, and the spontaneous movement of photogenerated holes to the outside of the molecular imprinted film, thereby greatly improving the elution process of the template molecule, and obtaining a MIPs sensor with light elution ability. During the illumination process, the molecular imprinted film has stronger detection ability, because the continuous irradiation of the molecular imprinted film can produce a large amount of specific holes, which is conducive to the adsorption of specific template molecules. In addition, the nitro group of chloramphenicol itself has electron attraction ability, therefore by breaking the molecular chain between the nitro group and the amino group, to achieve the effect of promoting the adsorption of chloramphenicol molecules with photogenerated holes.

[0083] We used K3[Fe(CN)6] as a probe reagent for the pores to detect the changes in specific pores. DPV tests were performed under the conditions of a scanning potential range of -0.1V to 0.5V and a scanning speed of 10mV / s. Figure 13As shown in the figure, the detection peak of the probe molecule at the working electrode increases with increasing chloramphenicol (CAP) concentration. However, when the concentration increases from 60 ppb to 80 ppb, the peak shape of the curve no longer changes significantly, indicating that the specific pores of the electrode may be saturated due to adsorption of chloramphenicol (CAP). After UV illumination of the sample group with 80 ppb, the DPV current peak of the electrode further increases, indicating that the photogenerated current continues to oxidize the imprinted membrane surface, increasing the concentration of specific pores. Therefore, photoelectroelution has the effect of increasing the detection current of this electrode.

[0084] Therefore, it is proved that the electrochemical sensor microdevice designed by the present invention is feasible for detecting antibiotic organic matter and can be effectively used for the rapid detection of chloramphenicol in real life. When the electrode detection capacity reaches saturation, the elution effect can continue to be achieved through the irradiation of the ultraviolet flashlight. This self-cleaning function extends the service life of the device.

[0085] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiment. They can be applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized.

Claims

1. A method for preparing a photoelectrochemical sensor for detecting chloramphenicol, characterized in that: include: S1: After attaching three layers of polyimide film to a titanium substrate, the film is cut and shaped to expose the working electrode position on the titanium substrate; titanium dioxide nanotubes are then prepared at the working electrode position by anodization; and molecularly imprinted films are polymerized on the surface of the titanium dioxide nanotubes through electrode reaction in an acidic system of aniline and chloramphenicol. S2: removing the first polyimide film on the titanium substrate, forming a silver film on the surface of the second polyimide layer through a silver mirror reaction, carving or cutting the silver film into a reference electrode and silver wires connecting the electrodes, and exposing the third polyimide film; S3: laser-induced graphene electrode on the third polyimide film as the counter electrode; The preparation method of the molecularly imprinted membrane is specifically as follows: In an acidic electrolyte system containing aniline and chloramphenicol, the titanium dioxide nanotubes are used as working electrodes, a graphite sheet is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode. An electrochemical workstation is used to first set a constant potential polarization program and then a cyclic voltammetry program to polymerize the molecular imprinted film on the surface of the titanium dioxide nanotubes; then, the chloramphenicol template is removed by ultraviolet irradiation and positive potential polarization. The method for generating the silver film is specifically as follows: The surface of the second polyimide film is modified with potassium hydroxide to form potassium polycarbamate; after cleaning, AgNO3 solution is dripped on the surface of the second polyimide film to achieve the replacement of silver ions with potassium ions in potassium polycarbamate; after cleaning, alkaline glucose solution is dripped on the surface of the second polyimide film to finally form a dense silver film with good conductivity on the surface of the second polyimide film.

2. The method for preparing a photoelectrochemical sensor for detecting chloramphenicol according to claim 1, wherein: The preparation method of the titanium dioxide nanotubes is specifically as follows: Step 1: Clean the titanium metal surface to obtain a titanium substrate; Step 2: Attach three layers of polyimide film to the surface of the titanium substrate and laser cut to expose the working electrode position; Step 3: In an electrolyte containing ammonium fluoride and ethylene glycol, the titanium substrate is used as the anode and the graphite sheet is used as the cathode. A DC power supply is used to set the constant voltage parameters to 50V and the time to 1800s for anodization. Then, the substrate is rinsed with alcohol and blown dry. Finally, the substrate is placed in a tube furnace and the initial temperature is set to 25°C, the heating rate is 5°C / min, the holding temperature is 500°C, and the holding time is 2 hours. Annealing is performed in air, and TiO2 transforms from an amorphous phase to anatase phase. At this point, the exposed metallic titanium is anodized to prepare dense titanium dioxide nanotubes.

3. The method for preparing a photoelectrochemical sensor for detecting chloramphenicol according to claim 2, wherein: The parameters of the constant potential polarization program were set as follows: polarization potential: -1.5 V, polarization time: 20 s; the parameters of the cyclic voltammetry program were set as follows: initial potential: -0.2 V, termination potential: 0.9 V, scan rate: 200 mV / s, and number of cycles:

10.

4. The method for preparing a photoelectrochemical sensor for detecting chloramphenicol according to claim 1, wherein: The preparation method of the counter electrode is specifically as follows: An ultraviolet marking machine was used for marking. The laser parameters were a wavelength of 355 nm, a frequency of 70 kHz, a focal length of 9.1 cm, a marking rate range of 10-30 mm / s, and a power of 20-30%. Graphene electrodes were obtained by laser induction.

5. A photoelectrochemical sensor for detecting chloramphenicol prepared by the preparation method according to claim 1, characterized in that: include: Titanium substrate, titanium dioxide nanotubes formed by oxidation on the titanium substrate, molecular imprinted film modified on the surface of the titanium dioxide nanotubes, a counter electrode and a reference electrode; The molecular imprinted membrane is a chloramphenicol molecular imprinted membrane formed by polymerizing chloramphenicol and aniline on a working electrode through electrode reaction and then removing chloramphenicol. The titanium dioxide nanotubes constitute the working electrode, and the molecular imprinted membrane constitutes the working surface of the working electrode.

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