SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin, preparation method and application thereof

Abstract

The present invention belongs to the technical field of sensor construction, and provides a SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin, its preparation method and application. The sensor includes an electrode substrate, and is surface-modified with a Bi3S2QDs / T-Ag NPs / Ti3C2 composite material and an enrofloxacin aptamer. The SERS-photoelectrochemical dual-mode sensor provided by the present invention uses Ti3C2 as the substrate material, combines silver nanoparticles with high SERS activity and quantum dots, improves the performance of the substrate, and expands the selection range of dual-mode electrodes. The SERS-photoelectrochemical dual-mode sensor constructed by the present invention combines the detection results of SERS and photoelectrochemical two modes to verify each other, avoids the misdiagnosis results of a single mode, makes the data more accurate and reliable, has a wide detection range, high sensitivity and low detection limit, and is of great significance for the detection of enrofloxacin.

Description

Technical Field

[0001] The present invention belongs to the field of detection, and particularly relates to a SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin, a preparation method thereof, and an application thereof. Background Art

[0002] Enrofloxacin (abbreviated as ENR), also known as ethylciprofloxacin and norfloxacin, belongs to fluoroquinolone synthetic antibacterial agents. Enrofloxacin is designated as a veterinary drug specifically for animals. It has strong antibacterial properties and is particularly easy to spread in animals. It is widely used in the animal and aquaculture industries. Currently, enrofloxacin has been listed as a key item for veterinary drug residue monitoring. The European Union stipulates that the maximum residue detection limit of ENR in animal-derived foods is 0.3 μg / g. Due to the excessive use of this veterinary drug, it accumulates and remains in large quantities in animals and is excreted through the excretion of animals, which has an impact on the surrounding environment. Among them, water resources have been severely polluted, and the health of humans and public health safety will be threatened. Therefore, an efficient and accurate method is needed to monitor the safety of water sources.

[0003] Various nanomaterials with high sensing performance and signal amplification strategies have been successively introduced into photoelectrochemical biosensors to meet the requirements for highly sensitive detection of enrofloxacin. However, a single detection mode often brings result deviation. Therefore, in order to meet the requirements of detection sensitivity, developing a multi-mode combination method to output multiple signals through the mutual verification of multiple groups of data, eliminating and avoiding abnormal diagnostic results of a single mode, and ensuring the accuracy of detection is an inevitable trend in biological tissue research and gene detection.

[0004] As two newly emerging detection technologies that have received much attention, SERS and photoelectrochemistry both exhibit the characteristics of rapid and sensitive detection. SERS can be applied to the detection of solid and liquid interfaces. However, due to the difficulty of laser focusing in the liquid environment, the detection time of SERS is relatively long. SERS provides rich fingerprint peaks, but for the reaction process of the same type of substances such as DNA hybridization, SPRS cannot identify them. Photoelectrochemistry is applicable to liquid detection and the detection time is relatively short. However, due to the progress of redox reactions, it cannot ensure that the properties of substances do not change. Whether the reaction occurs can be judged by the impedance change at the interface, but the overall information of the interface cannot be obtained. Summary of the Invention

[0005] The present invention aims to provide a preparation method and an application of a SERS-photoelectrochemical dual-mode sensor for highly accurate detection of enrofloxacin. The combination of SERS and photoelectrochemistry realizes the complementary advantages and mutual cooperation of the two modes, avoids abnormal diagnosis of a single mode, obtains more and richer detection information, outputs more accurate, complete and reliable detection results, and greatly improves the problems of insufficient reliability and sensitivity of most existing detection methods.

[0006] A SERS-photoelectrochemical dual-mode sensor for highly accurate detection of enrofloxacin, including an electrode substrate, with Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material and enrofloxacin aptamer modified on its surface;

[0007] The Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material consists of Bi3S2 QDs, T-Ag NPs (triangular silver nanoparticles), and Ti3C2 with a mass ratio of 1-5:1-5:1-5. In this range, the photocurrent performance is 0.74-2.53 μA, and the Raman signal response range at the characteristic peak of 1575 cm-1 is 254-2985. The change in mass ratio will change the photocurrent performance and Raman signal of the sensor. When the mass ratio is 3:2:4, the obtained optoelectronic signal and Raman signal response are the largest. Therefore, the most preferred mass ratio is 3:2:4.

[0008] The preparation method of the above SERS-photoelectrochemical dual-mode sensor for highly accurate detection of enrofloxacin includes the following steps:

[0009] (1) Preparation of Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material:

[0010] Mix Bi3S2 QDs, T-Ag NPs, and Ti3C2 in a solvent according to the mass ratio. After sufficient perturbation (the preferred perturbation condition is ultrasonic treatment for 30 min followed by normal temperature oscillation for 12 h), the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material can be obtained. Store the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material in the refrigerator for refrigerated use;

[0011] (2) Preparation of SERS-photoelectrochemical dual-mode sensor:

[0012] Drop the dispersion of the above Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material onto an electrode substrate (commonly used electrode substrates in the art, such as ITO, glassy carbon electrode, or FTO conductive glass), place it in a vacuum drying oven for drying, and then dropwise apply a certain concentration of enrofloxacin aptamer solution and dry it naturally at room temperature to obtain the SERS-photoelectrochemical dual-mode sensor.

[0013] The morphology of silver nanoparticles is the main factor affecting the SPR spectrum, and silver nanoparticles with different morphologies exhibit different SPR spectra. Compared with other morphologies, triangular silver nanoparticles have a special SPR spectrum, namely, three SPR peaks with weak out-of-plane quadrupole, in-plane quadrupole, and strong in-plane dipole resonances. In addition, the SPR spectrum of triangular silver nanoparticles also has the characteristics of structure dependence and artificial controllability, and the position of the SPR absorption peak can be regulated by changing the size, thickness, and arrangement of triangular silver nanoparticles. At the same time, since the quantum dots are also circular in shape, although the sizes of the two are different, triangular silver nanoparticles can be better distinguished from quantum dots.

[0014] Furthermore, in the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material in step (1), the concentration of Bi3S2 QDs is 3 mg / mL; the concentration of T-Ag NPs is 1 mg / mL; the concentration of the Ti3C2 suspension is 2 mg / mL; the concentration of the aptamer is 3.0 μmol / L; the volume ratio of the Bi3S2 QDs / T-Ag NPs / Ti3C2 dispersion to the aptamer solution is 2:1.

[0015] Furthermore, the preparation of Bi3S2 QDs:

[0016] First, 0.5 g of BSA and 16.0 mL of water were mixed in a 100 mL beaker and stirred rapidly until the BSA was completely dissolved in the water. Then, under vigorous stirring, 2.0 mL of a 2.0 M nitric acid solution containing 50 mM Bi(NO3)3·5H2O was slowly added, and stirring was continued for 0.5 h. 6.0 M sodium hydroxide was added to deprotonate the cysteine thiol group to adjust the pH value of the solution to 12, thereby stabilizing the formation of Bi2S3 quantum dots. The mixture was vigorously stirred at room temperature for half a day;

[0017] Furthermore, the preparation of T-Ag NPs includes: adding silver nitrate under stirring in pure water, then adding trisodium citrate and hydrogen peroxide, and rapidly injecting sodium borohydride into the solution for reduction.

[0018] The present invention also provides the application of the above SERS-photoelectrochemical dual-mode sensor in the detection of enrofloxacin, and the nucleotide sequence of the enrofloxacin aptamer is as follows:

[0019] Aptamer: 3′-CCC ATC AGG GGG CTA GGC TAA CAC GGT TCG GCT CTC TGA GCC CGGGTT ATT TCAGGG GGA-5′.

[0020] Furthermore, the specific detection method is as follows:

[0021] Step 1, prepare enrofloxacin standard solution. Weigh a certain mass of enrofloxacin and prepare a 1.0×10 -5 mol / L standard solution with methanol. Gradually dilute the standard solution with a phosphate buffer solution with pH = 7.4 containing potassium persulfate to obtain a series of enrofloxacin standard solutions with a concentration range of 1.0×10 -13 ~1.0×10 -5 mol / L.

[0022] Step 2, use the SERS-photoelectrochemical dual-mode sensor as the anode and the platinum electrode as the cathode. Use PBS buffer solution as the electrolyte. Control the current of the xenon light source to be 24 A, and the horizontal distance from the light source outlet to the ITO conductive surface to be 8 cm. Measure the photocurrent response value at a test potential of 0 V to obtain a series of concentration-photocurrent corresponding relationships, and then obtain the standard curve of enrofloxacin, establish a linear relationship between the photocurrent intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration, and obtain the corresponding linear regression equation;

[0023] Use the SERS-photoelectrochemical dual-mode sensor as the substrate material and analyze the sample with a Raman spectrometer of model LabRAM HR Evlution. The excitation wavelength λ = 633 nm, the accumulation times is 2, the exposure time is 2 s, the energy is 25%, and the power = 0.625 mW. Measure the Raman signal response value under this condition to obtain a series of concentration-Raman intensity corresponding relationships, and then obtain the standard curve of enrofloxacin, establish a linear relationship between the Raman intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration, and obtain the corresponding linear regression equation;

[0024] Step 3, sample detection. Carry out photoelectric and Raman tests respectively according to Step 2 above and obtain the photocurrent and Raman signal response values respectively. Calculate the obtained photocurrent value and Raman intensity with the linear regression equation obtained in Step 2 to obtain the concentration of enrofloxacin in the sample.

[0025] Preferably, the incubation time of the aptamer based on the SERS-photoelectrochemical dual-mode sensor is 30 min.

[0026] The remarkable advantage of the present invention is to develop a SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin and its preparation method. Compared with ordinary single-mode sensors, it has the following two remarkable advantages:

[0027] (1) The SERS-photoelectrochemical dual-mode sensor prepared by the present invention uses Ti3C2 as the substrate material, combines silver nanoparticles with high SERS activity and quantum dots, improves the performance of the substrate, expands the selection range of the dual-mode electrode, and under the same excitation light source, couples the photoelectrochemical and SERS devices, and can simultaneously obtain photoelectrochemical signals and spectral information, realizing mutual verification and mutual supplementation of the two detection signals, thereby reducing the probability of false positives or false negatives in the analysis and detection, achieving the ability to accurately analyze target pollutants, avoiding the misdiagnosis results of a single mode, and making the data more accurate and reliable;

[0028] (2) The SERS-photoelectrochemical dual-mode sensor prepared by the present invention is used for the detection of enrofloxacin. This sensor has high stability, good reproducibility, high sensitivity, and a wide linear range, and can achieve simple, rapid, highly sensitive and specific detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a brief flow chart of the preparation of the sensor in this invention and the detection of enrofloxacin.

[0030] Figure 2 is the photocurrent response diagram of enrofloxacin at different concentrations.

[0031] Among them, the concentrations of enrofloxacin are in ascending order of the curve peak as follows: 1.0×10 -13 mol / L (a), 1.0×10 -12 mol / L (b), 1.0×10 -11 mol / L (c), and 1.0×10 -10 mol / L (d), 1.0×10 -9 mol / L (e), 1.0×10 - 8 mol / L (f), 1.0×10 -7 mol / L (g), 1.0×10 -6 mol / L (h), 1.0×10 -5 mol / L (i).

[0032] Figure 3 is the standard curve of the luminescence intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration.

[0033] Figure 4 is the Raman signal response diagram of enrofloxacin at different concentrations.

[0034] Among them, the concentrations of enrofloxacin are in ascending order of the curve peak as follows: 1.0×10 -13 mol / L (a), 1.0×10 -12 mol / L (b), 1.0×10-11 mol / L (c), and 1.0×10 -10 mol / L (d), 1.0×10 -9 mol / L (e), 1.0×10 - 8 mol / L (f), 1.0×10 -7 mol / L (g), 1.0×10 -6 mol / L (h), 1.0×10 -5 mol / L (i).

[0035] Figure 5 is the standard curve of the Raman intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration. Specific embodiments

[0036] The present invention will be further described in detail below with reference to embodiments:

[0037] Example 1:

[0038] (1) Preparation of Bi3S2 QDs:

[0039] First, 0.5 g of BSA and 16.0 mL of water were mixed in a 100 mL beaker and stirred continuously until the BSA was completely dissolved in water. Then, under vigorous stirring, 2.0 mL of a 2.0 M nitric acid solution containing 50 mM Bi(NO3)3·5H2O was slowly added, and stirring was continued for 0.5 h. 6.0 M sodium hydroxide was added to deprotonate the cysteine thiol group to adjust the pH value of the solution to 12, thereby stabilizing the formation of Bi2S3 quantum dots. The mixture was vigorously stirred at room temperature for half a day;

[0040] (2) Preparation of T-Ag NPs:

[0041] In 96 mL of pure water, 200 μL of 50 mM silver nitrate was added under magnetic stirring. Then, 2 mL of trisodium citrate (75 mM) and 100 μL of hydrogen peroxide (30%) were added. Then, 1 mL of sodium borohydride (100 mM) was rapidly injected into the solution for reduction, immediately turning the solution light yellow. When the color of the solution turned dark purple, T-Ag NPs were formed;

[0042] (3) Preparation of Bi3S2 QDs / T-Ag NPs / Ti3C2 composite:

[0043] Mix Bi3S2 QDs, T-Ag NPs, and Ti3C2 in a volume ratio of 1:1:2. After ultrasonic treatment for 30 min and shaking at room temperature for 12 h, the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material can be obtained, and the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material is stored in the refrigerator for later use;

[0044] (4) Preparation of SERS-photoelectrochemical dual-mode sensor:

[0045] Drop-coat the dispersion of the Bi3S2 QDs / T-Ag NPs / Ti3C2 composite material prepared in step (3) on ITO conductive glass and dry it in a vacuum drying oven. The modified electrode thus prepared is denoted as Bi3S2QDs / T-Ag NPs / Ti3C2 / ITO; then, drop-coat a certain concentration of enrofloxacin aptamer on the prepared Bi3S2 QDs / T-Ag NPs / Ti3C2 / ITO and dry it naturally at room temperature to obtain the SERS-photoelectrochemical dual-mode aptamer sensor Bi3S2 QDs / T-Ag NPs / Ti3C2 / apt / ITO.

[0046] In the above sensor, the aptamer sequence is as follows: (ordered from Sangon Biotech (Shanghai) Co., Ltd.)

[0047] Aptamer: 3′-CCC ATC AGG GGG CTA GGC TAA CAC GGT TCG GCT CTC TGA GCC CGGGTT ATT TCAGGG GGA-5′.

[0048] (4) Plotting of the standard curve

[0049] Prepare an enrofloxacin standard solution. Weigh a certain mass of enrofloxacin and prepare a 1.0×10 -5 mol / L standard solution with methanol. Gradually dilute the standard solution with a phosphate buffer solution of pH = 7.4 containing potassium persulfate to obtain a series of enrofloxacin standard solutions with a concentration range of 1.0×10 -13 ~1.0×10 -5 mol / L;

[0050] Use the SERS-photoelectrochemical dual-mode sensor Bi3S2 QDs / T-Ag NPs / Ti3C2 / apt / ITO as the dual-mode substrate to perform photocurrent and Raman tests respectively to achieve the detection of enrofloxacin. The incubation time of the aptamer of the SERS-photoelectrochemical dual-mode sensor is 30 min, and the PBS buffer solution is used as the electrolyte to detect the photocurrent response value.

[0051] The dual-mode substrate was placed in a series of enrofloxacin concentrations (1.0×10 -13 mol / L, 1.0×10 -12 mol / L, 1.0×10 -11 mol / L, 1.0×10 -10 mol / L, 1.0×10 -9 mol / L, 1.0×10 -8 mol / L, 1.0×10 -7 mol / L, 1.0×10 - 6 mol / L, 1.0×10 -5 mol / L) in a 0.1 mol / L PBS buffer solution with pH 7.4 containing 0.1 mol / L of K2S2O8. Using the PBS buffer solution as the electrolyte, the current of the xenon light source was controlled at 24 A, the horizontal distance from the light source outlet to the ITO conductive surface was 8 cm, and the response value of the photocurrent was measured at a test potential of 0 V. A linear relationship between the luminescence intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration was established, and the corresponding linear regression equation was obtained: I = 3.3437 + 0.1969LogC (mol / L), and the correlation coefficient (R) was 0.9968. The detection range of the linear regression equation was 1.0×10 -13 ~1.0×10 -5 mol / L, and the lowest detection limit was 6.13×10 -14 mol / L.

[0052] Taking the modified electrode Bi3S2 QDs / T-Ag NPs / Ti3C2 / apt / ITO as the substrate material, a Raman spectrometer with the model of LabRAM HR Evlution was used to analyze the samples. The excitation wavelength λ = 633 nm, the accumulation times was 2, the exposure time was 2 s, the energy was 25%, and the power = 0.625 mW. Under this condition, the response value of the Raman signal was measured, a series of concentration-Raman intensity corresponding relationships were obtained, and then the standard curve of enrofloxacin was obtained. A linear relationship between the Raman intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration was established, and the corresponding linear regression equation was obtained: I = 4255.1897 + 307.9064LogC (mol / L), and the correlation coefficient (R) was 0.9979. The detection range of the linear regression equation was 1.0×10 -13 ~1.0×10 -5 mol / L, and the lowest detection limit was 2.14×10 -14 mol / L.

[0053] (6) Detection of samples

[0054] A certain amount of wastewater after filtration and impurity removal was added to a 0.1 mol / L PBS buffer solution with a pH of 7.4 containing 0.1 mol / L of K2S2O8 for photoelectrochemical and Raman detection. The enrofloxacin concentration in the sample to be detected was calculated according to the linear regression equation corresponding to step (5) above, and the results are listed in Table 1.

[0055] Comparative Example 1

[0056] (1) Preparation of Ti3C2 / ITO modified electrode

[0057] The ITO conductive glass was ultrasonically cleaned in deionized water and ethanol for half an hour in sequence, and then rinsed with deionized water multiple times. Then the conductive glass was put into a 0.1 mol / L NaOH aqueous solution, boiled, and maintained for 30 min, then washed with deionized water and dried in an oven for standby. 40 μL of the Ti3C2 suspension was pipetted and dropped onto the ITO conductive glass, and dried at room temperature to obtain the Ti3C2 / ITO modified electrode, which was used as the substrate material for dual-mode testing.

[0058] (2) Plotting of the standard curve

[0059] Using Ti3C2 / ITO as the substrate material, a dual-mode system was constructed for the detection of enrofloxacin, and the detection method was the same as that in Example 1.

[0060] Comparative Example 2:

[0061] (1) Preparation of Bi3S2 QDs / Ti3C2 / ITO modified electrode

[0062] The ITO conductive glass was ultrasonically cleaned in deionized water and ethanol for half an hour in sequence, and then rinsed with deionized water multiple times. Then the conductive glass was put into a 0.1 mol / L NaOH aqueous solution, boiled, and maintained for 30 min, then washed with deionized water and dried in an oven for standby. Bi3S2 QDs and Ti3C2 were mixed in a volume ratio of 1:2, ultrasonically treated for 30 min, and then shaken at room temperature for 12 h to obtain the Bi3S2 QDs / Ti3C2 composite material. 40 μL of Bi3S2 QDs / Ti3C2 was dropped onto the ITO conductive glass and dried at room temperature to obtain the Bi3S2 QDs / Ti3C2 / ITO modified electrode, which was used as the substrate material for dual-mode testing.

[0063] (2) Plotting of the standard curve

[0064] Using Bi3S2 QDs / Ti3C2 / ITO as the substrate material, a dual-mode system was constructed for the detection of enrofloxacin, and the detection method was the same as that in Example 1.

[0065] Comparative Example 3:

[0066] (1) Preparation of T-Ag NPs / Ti3C2 / ITO Modified Electrode

[0067] After the ITO conductive glass was ultrasonically cleaned in deionized water and ethanol for half an hour in sequence, it was rinsed with deionized water multiple times. Then the conductive ratio was put into 0.1 mol / L NaOH aqueous solution, boiled, and kept for 30 min, washed with deionized water and dried in an oven for later use. T-Ag NPs and Ti3C2 were mixed in a volume ratio of 1:2, ultrasonically treated for 30 min, and shaken at room temperature for 12 h to obtain the T-Ag NPs / Ti3C2 composite material. 40 μL of T-Ag NPs / Ti3C2 was dropped onto the ITO conductive glass and dried at room temperature to obtain the T-Ag NPs / Ti3C2 / ITO modified electrode as the substrate material for dual-mode testing.

[0068] (2) Plotting of Standard Curve

[0069] Using T-Ag NPs / Ti3C2 / ITO as the substrate material, a dual-mode system was constructed for the detection of enrofloxacin, and the detection method was the same as that in Example 1.

[0070] Table 1 Determination Results of Enrofloxacin in Water Samples

[0071]

[0072] As shown in Table 1, the samples were detected in parallel 3 times, the relative standard deviation was less than 5%, and the spiked recovery rate ranged from 95.9% to 101.7%. The above results show that the substrate materials modified with Bi3S2 QDs / Ti3C2 or T-Ag NPs / Ti3C2 alone without Bi3S2 QDs / T-Ag NPs / Ti3C2 / apt / ITO modification cannot achieve the dual-mode detection of enrofloxacin, and the present invention is feasible for the detection of enrofloxacin in wastewater. The lowest detection limit of the optoelectronic mode is 6.13×10 -14 mol / L, and the lowest detection limit of the Raman mode is 2.14×10 -14 mol / L.

[0073] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin, characterized in that: It includes an electrode substrate, with its surface modified with Bi3S2 QDs / T-AgNPs / Ti3C2 composite material and enrofloxacin aptamer; The Bi3S2 QDs / T-AgNPs / Ti3C2 composite material is composed of Bi3S2 QDs, T-AgNPs, and Ti3C2 compounded in a mass ratio of 1-5:1-5:1-5; The nucleotide sequence of the enrofloxacin aptamer is: 3′-CCC ATC AGG GGG CTA GGC TAA CAC GGT TCGGCT CTC TGA GCC CGG GTT ATT TCA GGG GGA-5′.

2. The SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin according to claim 1, characterized in that: The mass ratio of Bi3S2 QDs, T-AgNPs, and Ti3C2 is 3:2:

4.

3. The preparation method of the SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin according to claim 1 or 2, characterized in that: It includes the following steps: (1) Preparation of Bi3S2 QDs / T-AgNPs / Ti3C2 composite material: Mix Bi3S2 QDs, T-AgNPs, and Ti3C2 in a solvent. After sufficient agitation, a dispersion of Bi3S2 QDs / T-AgNPs / Ti3C2 composite material can be obtained and stored refrigerated for later use; (2) Preparation of SERS-photoelectrochemical dual-mode sensor: Drop the dispersion of the above Bi3S2 QDs / T-AgNPs / Ti3C2 composite material onto the electrode substrate, dry it in a vacuum drying oven, and then drop and coat a certain concentration of enrofloxacin aptamer solution, and let it dry naturally at room temperature to obtain the SERS-photoelectrochemical dual-mode sensor.

4. The preparation method of the SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin according to claim 3, characterized in that: In step (1), it includes separately preparing a 3mg / mL Bi3S2 QDs suspension, a 1mg / mL T-AgNPs suspension, a 2mg / mL Ti3C2 suspension, and a 3.0μmol / L aptamer solution; the volume ratio of the dispersion of Bi3S2 QDs / T-AgNPs / Ti3C2 composite material to the aptamer solution is 2:

1.

5. The preparation method of the SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin according to claim 3, characterized in that: The agitation condition in step (1) is: ultrasonic for 30min and then shaken at room temperature for 12h.

6. The preparation method of the SERS-photoelectrochemical dual-mode sensor for detecting enrofloxacin according to claim 3, characterized in that: The preparation of T-AgNPs includes: adding silver nitrate under stirring in pure water, then adding trisodium citrate and hydrogen peroxide, and quickly injecting sodium borohydride into the solution for reduction.

7. A method for detecting enrofloxacin using the SERS-photoelectrochemical dual-mode sensor according to claim 1 or 2, characterized in that: It includes the following steps: 1) Prepare a PBS buffer solution containing K2S2O8; 2) Prepare standard solutions of enrofloxacin with different concentrations; Prepare an enrofloxacin standard solution. Weigh a certain mass of enrofloxacin and prepare a 1.0×10 -5 mol / L standard solution with methanol. Gradually dilute the standard solution with a phosphate buffer solution with pH = 7.4 containing potassium persulfate to obtain a series of enrofloxacin standard solutions with a concentration range of 1.0×10 -13 ~1.0×10 -5 mol / L; 3) Plot the standard curve Take a series of known-concentration enrofloxacin standard solutions from step 2) and drop and coat them on the SERS-photoelectrochemical dual-mode sensor, and let it dry naturally at room temperature to obtain the modified electrode; Use the modified electrode as the anode and a platinum electrode as the cathode, use the buffer solution from step 1) as the electrolyte, control the current of the xenon light source to be 24A, the horizontal distance from the light source outlet to the conductive surface of the electrode substrate to be 8cm, measure the photocurrent response value at a test potential of 0V, obtain a series of concentration-photocurrent corresponding relationships, and then obtain the standard curve of enrofloxacin, establish a linear relationship between the photocurrent intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration, and obtain the corresponding linear regression equation; Using the modified electrode as the substrate material, the sample was analyzed with a Raman spectrometer of model LabRAM HR Evlution. The excitation wavelength was λ = 633 nm, the accumulation times was 2, the exposure time was 2 s, the energy was 25%, and the power was 0.625 mW. The response value of its Raman signal was measured to obtain a series of concentration-Raman intensity correspondence relationships, and then the standard curve of enrofloxacin was obtained. A linear relationship between the Raman intensity after adding enrofloxacin and the logarithm of the enrofloxacin concentration was established to obtain the corresponding linear regression equation; 4) Sample detection For sample detection, pretreatment was first carried out and then the pH was adjusted. The concentration of enrofloxacin in the sample was calculated according to the linear regression equation in step 3) above.

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