Construction of self-powered sensor based on HOF-on-MOF and application research of self-powered sensor in enrofloxacin in mandarin fish

Abstract

The invention discloses construction of a self-energized sensor based on HOF-on-MOF and application research of enrofloxacin in mandarin fish, and belongs to the field of self-energized sensing, a photocathode material and a photoanode material required by the self-energized sensor are prepared by applying a hydrothermal synthesis method, the self-energized sensor is constructed by utilizing the photocathode material, and the self-energized sensor is used for detecting enrofloxacin in mandarin fish. An aptamer (Apt) is successfully combined to a photocathode, the self-powered photoelectrochemical aptamer sensor is constructed, the photocurrent value of the self-powered sensor is linearly related to the logarithm of the concentration of enrofloxacin (ENR), the photocurrent value after the ENR is added is substituted into a linear regression equation of a standard curve drawn by the photocurrent and the logarithm of the concentration, and the self-powered photoelectrochemical aptamer sensor is constructed. Compared with an existing ENR detection method, the method has the advantages that the detection range is wider (1.0 * 10 <-11 >-1.0 * 10 <-6 > mol / L) and the detection limit is lower (3.3 * 10 <-12 > mol / L), and trace detection of the ENR can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectrochemical detection, and particularly relates to a preparation method of a self-powered sensor and application of the self-powered sensor in detection of ENR. BACKGROUND

[0002] Enrofloxacin (ENR) is a fluoroquinolone antibiotic with broad-spectrum bactericidal effect. It is widely used in livestock breeding and aquaculture. However, if ENR is used improperly, such as exceeding the specified standard of dosage or not complying with the drug withdrawal requirement before the animals are slaughtered or the plants are harvested, ENR is likely to be left in the animal body. Long-term consumption of animals containing ENR can cause accumulation of ENR in the human body, which may cause damage to organs such as liver and kidney, and affect the immune system and hematopoietic function of the human body. Especially for children, it may affect the development of bones and teeth. After ENR enters the soil, it will also be left and accumulated in the soil, affecting the activity and community structure of soil microorganisms, and further affecting the fertility and ecological function of the soil. At present, the methods for detecting ENR residues include chemiluminescence method, electrochemical method, liquid chromatography method and the like. On the one hand, these methods need to use expensive instruments, and on the other hand, the detection range is narrow and the detection limit is high, which cannot be used for trace detection. SUMMARY

[0003] The application aims to solve the problems of narrow detection range and high detection limit of the existing ENR detection method, and provides a self-powered sensor and a preparation method thereof and application of the self-powered sensor in detection of ENR. The self-powered sensor is constructed by using a hydrogen-bonded organic framework-on-metal organic framework (HOF-on-MOF) composite material as a light cathode and an In2S3@CdIn2S4 composite material as a light anode, and has a wider linear range (1.0x10 -11 ~ 1.0x10 -6 mol L -1 ) and a lower detection limit (3.3x10 -12 mol L -1 ) than the existing detection method, and the detection process is self-powered, which avoids the influence of interfering substances on the experimental results.

[0004] To solve the above technical problems, the application provides a self-powered sensor for detecting ENR, which is constructed by using an ENR aptamer combined with a HOF-on-MOF composite material as a light cathode electrode, an In2S3@CdIn2S4 composite material as a light anode electrode, and a PBS buffer salt solution as an electrolyte.

[0005] Further, the HOF-on-MOF composite material is obtained by compounding a MOF material treated by tannic acid and a HOF material constructed by 1,3,6,8-tetra(4-carboxyphenyl)pyrene; and the In2S3@CdIn2S4 composite material is obtained by dispersing In2S3 into CdCl2·2.5H2O.

[0006] Preferably, the PBS buffer solution has a pH value of 8 and a concentration of 0.1 mol / L.

[0007] To solve the above technical problems, the application further provides a preparation method of the self-powered sensor, comprising the following steps:

[0008] (1) dispersing the In2S3@CdIn2S4 composite material in deionized water to obtain an In2S3@CdIn2S4 dispersion liquid, coating the In2S3@CdIn2S4 dispersion liquid on an ITO surface and drying to obtain an In2S3@CdIn2S4 / ITO photoanode;

[0009] (2) dispersing the HOF-on-MOF composite material in deionized water to obtain a HOF-on-MOF dispersion liquid, coating the HOF-on-MOF dispersion liquid on an ITO surface and drying to obtain a HOF-on-MOF / ITO photocathode;

[0010] (3) adding a chitosan solution on the surface of the HOF-on-MOF / ITO photocathode and drying, then adding a glutaraldehyde solution on the surface of the HOF-on-MOF / ITO photocathode, standing and reacting, modifying ENRApt on the surface of the photocathode, incubating at 4 DEG C for 12 hours, and then blocking the photocathode with bovine serum albumin to obtain an Apt / HOF-on-MOF / ITO photocathode.

[0011] Further, the preparation process of the In2S3@CdIn2S4 composite material is as follows: dissolving In(NO3)3·5H2O in anhydrous ethanol, adding carbon disulfide, reacting at 180 DEG C for 18 hours, adding thioacetamide, continuously reacting for 12 hours, filtering out the precipitate and drying to obtain In2S3 nanospheres; dispersing the In2S3 nanospheres into CdCl2·2.5H2O, stirring and heating at 60 DEG C for 300 seconds, centrifuging and drying to obtain the In2S3@CdIn2S4 composite material.

[0012] Further, the preparation process of the HOF-on-MOF composite material is as follows: adding a MOF material treated by tannic acid into ethanol and stirring to obtain solution C; adding DMF into 1,3,6,8-tetra(4-carboxyphenyl)pyrene to dissolve and obtain solution D; mixing solution C and solution D, stirring at 80 DEG C for 4 hours, centrifuging to collect the precipitate, washing and drying to obtain the HOF-on-MOF composite material.

[0013] Further, the preparation process of the MOF material is as follows: Zn(NO3)2·6H2O is dissolved in methanol to form a uniform solution A, 2-methylimidazole is dissolved in methanol to form a uniform solution B; solution A and solution B are mixed into a mixed solution under stirring, and are left to stand for 12 hours; the precipitate is collected by centrifugation, and is washed and dried to obtain the MOF material.

[0014] Further, the tannic acid treatment process is as follows: tannic acid is dispersed into a methanol solution to obtain a methanol solution of tannic acid, the MOF material is poured into the methanol solution of tannic acid to obtain a suspension, the suspension is stirred for 30 minutes, and the MOF material treated with tannic acid is obtained by centrifugation, washing and drying.

[0015] To solve the above technical problems, the application further provides an application of the self-powered sensor in detection of ENR, comprising the following steps: dropping a to-be-detected solution on an Apt / HOF-on-MOF / ITO photo-cathode, and incubating to obtain a modified electrode marked as ENR / Apt / HOF-on-MOF / ITO; taking the ENR / Apt / HOF-on-MOF / ITO as a photo-electrochemical test photo-cathode, taking In2S3@CdIn2S4 / ITO as a photo-anode, and taking a PBS buffer salt solution as an electrolyte to form a self-powered sensor, vertically irradiating two stages by a xenon lamp light source, testing a photo-current of the self-powered sensor, and substituting a photo-current value after ENR is added into a linear regression equation of a standard curve drawn by a photo-current and a concentration logarithm to calculate a concentration of ENR in the to-be-detected solution.

[0016] Preferably, the temperature of the incubation is 37 DEG C, and the time is 40 minutes; and the power of the xenon lamp is 300 W.

[0017] Under light irradiation, the In2S3@CdIn2S4 / ITO photo-anode and the HOF-on-MOF / ITO photo-cathode both generate electron-hole pairs, the aptamer is combined with the HOF-on-MOF / ITO photo-cathode through a covalent bond, the aptamer is connected to the surface of the photo-cathode, the electron migration rate is reduced, and the photoelectric signal response is weakened. Then the to-be-detected substance ENR is introduced into the system, the photoelectric response is reduced, which indicates that the ENR forms a complex with the aptamer fixed on the surface of the photo-cathode, and it is proved that the self-powered sensor of the application is successfully applied to detection of ENR.

[0018] Compared with the existing detection method, the self-powered sensor of the application has the following beneficial effects:

[0019] The application utilizes a hydrothermal synthesis method to prepare cathode materials and anode materials required by self-powered sensors with excellent performance, and the photoelectric conversion efficiency of single materials is effectively improved after In2S3 and CdIn2S4, and MOF and HOF materials are compounded under the irradiation of a xenon light source; moreover, the photoelectric output signal of the self-powered sensor constructed by the composite material shows a downward trend with the gradual increase of the ENR concentration, and the photocurrent value is linearly related to the logarithm of the ENR concentration; by substituting the photocurrent value after the addition of ENR into the linear regression equation of the standard curve drawn by the photocurrent and the logarithm of the concentration, the concentration of ENR in the to-be-measured solution can be calculated, and compared with the existing detection method in which the corresponding signal is linearly related to the concentration of the to-be-measured substance, the photocurrent value is linearly related to the logarithm of the ENR concentration, which can greatly widen the linear range (1.0*10 -11 ~ 1.0*10 -6 mol / L -1 ) and the lower detection limit (3.3*10 -12 mol / L -1 ) of detection, the detection process is self-powered, the influence of interfering substances on the experimental results is avoided, and the detection result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 are TEM images of In2S3 nanospheres (A), In2S3@CdIn2S4 composite materials (B), MOF materials (C) and HOF-on-MOF composite materials (D);

[0021] Figure 2 are XRD images of In2S3 nanospheres (a) and In2S3@CdIn2S4 composite materials (b);

[0022] Figure 3 are XRD images of HOF materials (a), MOF materials (b) and HOF-on-MOF composite materials (c);

[0023] Figure 4 is an XPS image of In2S3@CdIn2S4 composite materials;

[0024] Figure 5 are UV-Vis diffuse reflectance spectra and Tauc images of In2S3 nanospheres (a) and In2S3@CdIn2S4 composite materials (b);

[0025] Figure 6 are UV-Vis diffuse reflectance spectra and Tauc images of HOF materials (a) and HOF-on-MOF composite materials (b);

[0026] Figure 7is the Mott-Schottky plot of In2S3@CdIn2S4 / ITO photoanode (A) and HOF-on-MOF / ITO photocathode (B);

[0027] Figure 8 is the open circuit potential of the self-powered sensor prepared under light (a) and dark (b) conditions;

[0028] Figure 9 is the I-T curve (A) and EIS spectrum (B) of the photocathode HOF-on-MOF / ITO (a), Apt / HOF-on-MOF / ITO (b) and ENR / Apt / HOF-on-MOF / ITO (c);

[0029] Figure 10 is the effect of pH value of PBS buffer solution on photocurrent I;

[0030] Figure 11 is the effect of aptamer concentration on photocurrent I;

[0031] Figure 12 is the effect of incubation time of ENR on photocurrent I;

[0032] Figure 13 is the I-T curve (A) and calibration curve of photocurrent and ENR concentration (B) under different ENR concentrations. DETAILED DESCRIPTION

[0033] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application.

[0034] Embodiment 1 A method for preparing a self-powered sensor, comprising the following steps:

[0035] (1) Preparation of MOF material:

[0036] Zn(NO3)2·6H2O (zinc nitrate hexahydrate, 2.3800 g, 8 mmol) and 2-methylimidazole (2-Melm, 1.3136 g, 16 mmol) were dissolved in 2 50 mL of methanol to form uniform solution A and solution B; under magnetic stirring, solution B was poured into solution A to obtain a mixed solution, which was left to stand for 12 h; the centrifuge speed was set to 8000 rpm, and the precipitate was collected after centrifuging the mixed solution for 5 min, washed several times with anhydrous ethanol (EtOH) and dried in a vacuum oven at 60°C to obtain the MOF material ZIF-8;

[0037] (2) Preparation of HOF material:

[0038] Take 0.1003 g H4TBAPy (1,3,6,8-tetra(4-carboxyphenyl)pyrene, 100 mg, 0.15 mmol) into a container, add 10 mL DMF and ultrasonic for 2 min; the container is heated in an 80°C oil bath and stirred for 2 h, then the solution is transferred to a 250 mL beaker containing 200 mL EtOH and stirred for 4 h (set the speed to 500 rpm), centrifuged by centrifuge and washed with EtOH several times, placed in a 60°C air drying oven for 6 h, and a bright yellow solid powder is obtained, which is HOF material;

[0039] (3) Preparation of HOF-on-MOF composite material:

[0040] Disperse 1 g of tannic acid (TA) in 200 mL of methanol solution to obtain a methanol solution of tannic acid; pour 60 mg of MOF material ZIF-8 into the methanol solution of tannic acid; the suspension is magnetically stirred for 30 min, centrifuged by high-speed centrifuge and washed with EtOH three times, and dried in a vacuum oven to obtain tannic acid (TA) treated MOF material ZIF-8-YS;

[0041] Add 30 mg of tannic acid (TA) treated MOF material ZIF-8-YS to 100 mL of ethanol solution and stir for 2 h to obtain ethanol solution C of ZIF-8-YS;

[0042] Pour H4TBAPy (0.1 g) into a 50 mL round-bottom flask, add 10 mL DMF and mix well to obtain solution D, heat the round-bottom flask in an 80°C oil bath and stir at medium-low speed for 2 h, transfer solution D to solution C, stir for 4 h, wash with DMF and EtOH alternately three times after centrifugation, and dry in a vacuum drying oven to obtain HOF-on-MOF composite material;

[0043] (4) Preparation of In2S3@CdIn2S4 composite material:

[0044] Dissolve 1 mmol of In(NO3)3·5H2O in 60 mL of anhydrous ethanol, add 2 mL of CS2 while stirring, transfer to a reaction kettle, react at 180°C for 18 h, add 1 mmol of C2H5NS, continue to react at 180°C in a high-pressure kettle for 12 h, filter out the orange precipitate and dry in a vacuum oven at 60°C to obtain In2S3 nanospheres;

[0045] Take 50 mg of In2S3 nanospheres and disperse them in CdCl2·2.5H2O (150 mL, 30 mg / L), stir at low speed and heat at 60°C for 300 s, high-speed centrifuge with a high-speed centrifuge and dry in a vacuum drying oven to obtain In2S3@CdIn2S4 composite material;

[0046] (5) Construction of self-powered sensor:

[0047] An indium tin oxide (ITO) electrode with a size of 1 cm x 2 cm was pretreated and washed with toluene, acetone, ethanol and deionized water in sequence. Then, 4.0 mg of the photoanode In2S3@CdIn2S4 composite material was dispersed in 2 mL of deionized water to obtain a photoanode In2S3@CdIn2S4 composite material dispersion with a concentration of 2.0 mg / mL by ultrasonic oscillation. Then, 20 μL of the photoanode In2S3@CdIn2S4 composite material dispersion was coated on the ITO surface with a working area of 0.09 π cm 2 , and dried under an infrared light lamp to obtain a photoanode In2S3@CdIn2S4 / ITO.

[0048] The same method was used to prepare a cathode HOF-on-MOF / ITO.

[0049] A self-powered sensor was constructed using the HOF-on-MOF / ITO as the cathode, the In2S3@CdIn2S4 / ITO as the anode, and a PBS buffer solution as the electrolyte.

[0050] Example 2 Construction of a self-powered photoelectrochemical aptamer sensor, including the following steps:

[0051] 10 μL of a 0.1% chitosan (CS) solution was added dropwise to the cathode HOF-on-MOF / ITO and dried under an infrared light. Then, 20 μL of a 2.5% glutaraldehyde (GA) solution was added dropwise to the surface of the cathode HOF-on-MOF / ITO, and after standing for 1 h, the excess GA was slowly washed away with a PBS buffer solution (pH = 8). 20 μL of an ENR aptamer with a concentration of 3.0 μmol / L was modified on the surface of the cathode, and incubated at 4°C for 12 h. The electrode surface was then washed with PBS to remove the unbound aptamer molecules. Next, the electrode was blocked with 20 μL of a 3% bovine serum albumin (BSA) solution for 30 min, and then washed with PBS again to remove the residual BSA, thereby obtaining a pure photoelectrode surface and an aptamer-modified cathode Apt / HOF-on-MOF / ITO.

[0052] A self-powered photoelectrochemical aptamer sensor was constructed using the Apt / HOF-on-MOF / ITO as the cathode, the In2S3@CdIn2S4 / ITO as the anode, and a PBS buffer solution as the electrolyte.

[0053] Example 3 Performance characterization, including the following items:

[0054] 1. Characterization of photoelectrode,

[0055] Characterization of materials: The morphology of the prepared materials was characterized by a Japanese Electronics JEOL 2100 transmission electron microscope (TEM), and the results are shown in Figure 1 , Figure 1 (A) shows that In2S3 is a hollow nanosphere with a cavity structure; from Figure 1 (B) it can be seen that the In2S3@CdIn2S4 composite material is also a hollow nanosphere with a cavity structure, but the surface becomes rough and uneven, proving that a hollow In2S3@CdIn2S4 heterojunction is obtained without destroying the morphology of In2S3, and a heterojunction is successfully constructed by ion exchange between In 3+ and Cd 2+ ; from Figure 1 (C) it can be seen that the particle diameter of the MOF material is about 1.5 microns, and it has a standard hexagonal structure with a smooth surface; from Figure 1 (D) it can be seen that after the introduction of HOF, the MOF material still retains its original shape, but presents a wrapped structure.

[0056] X-ray diffraction characterization: The crystal structure of the samples was studied by a Bruker D8 X-ray diffraction (XRD) spectrum, and the results are shown in Figure 2 , Figure 3 , wherein Figure 2 shows the phase and crystal structure of In2S3 nanospheres and In2S3@CdIn2S4 composite materials, and according to the standard spectrum (JPCDS No. 05-0731), all the diffraction peaks can be easily identified as In2S3 phase (curve a); according to the standard card (JCPDS No. 31-0229), a new phase CdIn2S4 is generated in the figure (curve b), indicating that In 3+ is partially exchanged by Cd 2+ , forming an In2S3@CdIn2S4 heterojunction. Figure 3 In the middle (curve a), a strong and sharp peak appears at 8.3°, indicating that there is a stacking mode in the HOF material, and this stacking mode ensures the porous structure in the framework and the large specific surface area. Figure 3 The good match of the peak position in the middle (curve b) confirms the phase purity of the MOF crystal, and the HOF-on-MOF composite material (curve c) has the same peak position as curve b at 6.2°, 10.4°, 13.5°, 17.2°, and 18.3°, indicating that the MOF is anchored on the HOF, and the composite material can maintain high crystallinity and phase purity.

[0057] X-ray photoelectron spectroscopy characterization: X-ray photoelectron spectroscopy (XPS) was used to study the chemical composition and surface bonding, and to characterize the materials. Figure 4 (A) shows the high-resolution full spectrum of In2S3@CdIn2S4 composite material, in which three peaks at 450.1 eV, 400.2 eV and 160.6 eV correspond to In 3d, Cd 3d and S 2p respectively, thus confirming the presence of Cd, In and S elements. Figure 4 The two significant peaks presented in (B) are located at 412.3 eV and 405.7 eV, which are clearly attributed to the 3d 5 / 2 and 3d3 / 2 energy levels of Cd, respectively. Figure 4 In (C), another obvious peak can be observed at 445.5 eV, which corresponds to the 3d 5 / 2 energy level of In; while the peak at 452.5 eV is attributed to the 3d 3 / 2 energy level of In. Figure 4 (D) shows the spectrum of S 2p, in which two peaks at 161 eV and 162.5 eV are clearly visible, which correspond to the 2p 3 / 2 and 2p 1 / 2 energy levels of S, respectively.

[0058] UV-Vis diffuse reflectance spectroscopy characterization: In order to study the optical properties of the hollow materials in the photoanode and the materials in the photocathode, UV-Vis diffuse reflectance experiments were carried out, as shown in Figure 5 , Figure 6 From the UV-Vis diffuse reflectance spectrum Figure 5 , it can be seen that the absorption wavelength of In2S3 is about 370 nm, and the light absorption range of In2S3@CdIn2S4 composite material is about 500 nm. It is possible that the formation of heterojunction promotes the separation of photo-generated carriers and improves the light absorption rate. From the Tauc plot Figure 5 , it can be seen that the Eg values of In2S3 and In2S3@CdIn2S4 are 2.39 eV and 2.30 eV, respectively. It can be seen that In2S3@CdIn2S4 (curve b) has a wider absorption range and higher charge transfer rate in the visible light region than In2S3 (curve a). From the UV-Vis diffuse reflectance spectrum Figure 6 , it can be seen that the light absorption range of the single HOF material is 500 nm, and the Eg values of the HOF-on-MOF composite material (curve a) and the HOF material (curve b) are 2.45 eV and 2.53 eV, respectively, indicating that the light absorption range of the HOF-on-MOF composite material remains unchanged, while the light absorption intensity and the charge transfer rate are significantly enhanced.

[0059] 2. Study of the energy band of self-powered sensor:

[0060] The electronic properties of the materials were quantitatively evaluated by electrochemical Mott-Schottky analysis method, and the band structure characteristics of the MOF and HOF and In2S3 and CdIn2S4 composite materials were explored, and the results are shown in Figure 7 Figure 7 The positive slope of the curve in (A) indicates that the In2S3@CdIn2S4 composite material is an n-type semiconductor, and the flat band potential (Vfb) of the In2S3@CdIn2S4 composite material is obtained from (A) as -0.55 V. Figure 7 Figure 7 The negative slope of the curve in (B) proves that the HOF-on-MOF composite material is a p-type semiconductor, and the V Figure 7 fb The difference constitutes a power source for energy conversion and signal generation. In an electrochemical sensor, when light is activated, the heterojunction bipolar electrode generates electron-hole pairs, and based on the difference in Fermi energy level, the photo-generated electrons of the anode flow to the cathode through the external circuit and combine with the photo-generated holes of the cathode to form a closed loop, triggering the generation of a photoelectric signal.

[0061] 3. Characterization of the performance of the self-powered sensor:

[0062] The open circuit potential (OCP) of the self-powered sensor was experimentally investigated, and the experimental data are shown in Figure 8 Figure 8 It is revealed that under light conditions (curve a), the response degree of the OCP signal is significantly improved compared to the non-light state (curve b), up to 8 times of the latter, and the results show that light plays a crucial role in the photoelectric output performance of the self-powered sensor.

[0063] 4. Characterization of the aptamer preparation process of the self-powered sensor:

[0064] Figure 9 (A) The strongest photocurrent signal (curve a) is HOF-on-MOF / ITO photocathode, which is due to its excellent charge transfer and separation efficiency, and curve b is the aptamer modified photocathode Apt / HOF-on-MOF / ITO. Due to the presence of aptamer, the transfer of electrons is hindered, and the photocurrent signal decreases. When the ENR target molecule is introduced, the aptamer specifically captures ENR, and the photocurrent signal continues to decrease (curve c). The charge transfer process during the gradual assembly of the sensor was further analyzed using electrochemical impedance spectroscopy (EIS) data, as shown in Figure 9 (B) When the aptamer is modified on the photocathode HOF-on-MOF / ITO, the R et ​​​​The value increased from 204.5 (curve a) to 908.6 Ω (curve b), indicating that the aptamer was successfully anchored on the HOF-on-MOF / ITO photocathode. In the presence of the target material ENR, R... et The value increased to 1109.3Ω (curve c), and this phenomenon is related to... Figure 7 This corresponds to the photocurrent signal in (A).

[0065] 5. Parameter optimization:

[0066] pH optimization of PBS buffer: As the pH of the PBS buffer solution gradually increases from 3 to 8, the corresponding current signal shows a gradual increasing trend, such as... Figure 10 As shown, when the pH value reaches 8, the current signal significantly increases to its maximum value, 1.18 μA. However, when the pH value exceeds this threshold, the current signal shows a decreasing trend. Based on the experimental observations, pH 8 is determined to be the optimal pH condition for the PBS buffer solution.

[0067] Optimization of aptamer concentration: In studying the photoelectric output characteristics of a self-powered photoelectrochemical aptamer sensor, it was found that aptamer concentration has a significant impact on sensor performance. To achieve optimal detection efficiency, the optimal concentration of the ENR aptamer was systematically optimized, such as... Figure 11 As shown, the current value decreases in the range of aptamer concentration from 1.0 to 5.0 μmol / L; in particular, when the aptamer concentration exceeds 3.0 μmol / L, the current value tends to stabilize, forming a relatively constant sensor platform. Therefore, 3.0 μmol / L is determined as the optimal working concentration of the aptamer.

[0068] Optimization of ENR incubation time: The length of material incubation time plays a crucial role in the sensor's output performance. To achieve optimal detection efficiency, the ENR incubation time was optimized, such as... Figure 12 As shown, when the incubation time increases from 20 min to 30 min, the current value gradually increases, while when the incubation time is 40 min, the current value reaches a stable value and then remains basically unchanged. Therefore, 40 min is selected as the optimal incubation time for ENR.

[0069] Example 4: Self-powered sensor for ENR detection:

[0070] Based on the optimal conditions obtained in Example 3, the ENR was detected, and the specific process was as follows:

[0071] Different concentrations of ENR (20 μL) were dropped onto the aptamer-modified photocathode Apt / HOF-on-MOF / ITO. After incubation at 37 °C for 40 min, the unreacted ENR on the photoanode was washed with PBS buffer solution to obtain the photocathode. The photocathode was then tested with the In2S3@CdIn2S4 / ITO photoanode in PBS buffer solution. The In2S3@CdIn2S4 / ITO photoanode and the ENR / Apt / HOF-on-MOF / ITO photocathode were placed in the buffer solution, and the two electrodes were vertically irradiated by a 300W xenon lamp light source to test their photoelectric signals.

[0072] from Figure 13 (A) It can be seen that as the ENR concentration (C) increases... ENR As the ENR complex gradually increases, the photoelectric output signal shows a downward trend. This is because more ENR complexes adhere, increasing the steric hindrance on the photoelectrode surface. Figure 13 (B) indicates the logarithm (lg C) of photocurrent value (I) and ENR concentration. ENR ) shows a linear correlation (R 2 =0.996), the regression equation is I = 0.0865lg C ENR -0.153, concentration detection range is 1.0×10 -11 ~1.0×10 -6 Compared with currently published ENR detection methods (as shown in Table 1), the self-powered photoelectrochemical aptamer sensor constructed in this invention spans six orders of magnitude, achieving trace detection of ENR with a detection limit of 3.3 × 10⁻⁶ mol / L. -12 It also has the lowest concentration (mol / L).

[0073] Table 1. Comparison of analytical performance of several methods for determining ENR

[0074]

[0075] Example 5: Detection Case

[0076] Mandarin fish purchased from the market was used as the test sample and pretreated as follows: 2.0 g of mandarin fish sample was crushed and then immersed in acetonitrile / deionized water (V / V = 7 / 3, 5.0 mL), vortexed for 3 min, sonicated for 15 min, and the fish meat sample was centrifuged at 5000 rpm for 10 min to remove large particles. After centrifugation, the solution was filtered through a 0.22 μm microporous membrane, diluted 25 times with deionized water, and then added according to the standard addition method to obtain a concentration of 10... -9 10 -8 and 10 -7 A mol / L ENR standard solution was added to the mandarin fish sample for analysis, and the result was determined according to the regression equation I = 0.0865lg C corresponding to the standard curve.ENR The concentration of ENR in the sample was calculated using -0.153, and the results are listed in Table 2.

[0077] Each sample was tested in parallel three times, and the relative standard deviation of the three samples was less than 1.6%. The spiked recovery rate was 95% to 106.3%, indicating that the self-powered sensor of the present invention can be used to detect ENR in samples.

[0078] Table 2. Test results of mandarin fish samples

[0079]

[0080] The above description is merely the preferred embodiment of the present invention. It should be noted that, for those skilled in the art, various modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the principle of the present invention, and these modifications or substitutions can also achieve the technical effects of the present invention, and should also be considered to fall within the protection scope of the present invention.

Claims

1. A self-powered sensor for detecting ENR, characterized in that: A self-powered sensor was constructed using ENR aptamer-bonded HOF-on-MOF composite material as the photocathode electrode, In2S3@CdIn2S4 composite material as the photoanode electrode, and PBS buffer solution as the electrolyte.

2. The self-powered sensor according to claim 1, characterized in that: The HOF-on-MOF composite material is composed of a tannic acid-treated MOF material and an HOF material constructed from 1,3,6,8-tetra(4-carboxyphenyl)pyrene; the In2S3@CdIn2S4 composite material is obtained by dispersing In2S3 into CdCl2·2.5H2O.

3. The self-powered sensor according to claim 1, characterized in that: The pH of the PBS buffer solution is 8, and the concentration is 0.1 mol / L.

4. The method for preparing the self-powered sensor according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The In2S3@CdIn2S4 composite material was dispersed in deionized water to obtain an In2S3@CdIn2S4 dispersion. The In2S3@CdIn2S4 dispersion was coated on the surface of ITO and dried to obtain an In2S3@CdIn2S4 / ITO photoanode. (2) The HOF-on-MOF composite material was dispersed in deionized water to obtain the HOF-on-MOF dispersion; the HOF-on-MOF dispersion was coated on the surface of ITO and dried to obtain the HOF-on-MOF / ITO photocathode; (3) Chitosan solution was added to the surface of HOF-on-MOF / ITO photocathode and dried; then glutaraldehyde solution was added to the surface of HOF-on-MOF / ITO photocathode and allowed to stand for reaction; Apt was modified on the surface of photocathode and incubated at 4°C for 12 h; then bovine serum albumin was used to block the photocathode to obtain Apt / HOF-on-MOF / ITO photocathode.

5. The preparation method according to claim 4, characterized in that, The preparation process of In2S3@CdIn2S4 composite material is as follows: In(NO3)3·5H2O is dissolved in anhydrous ethanol, carbon disulfide is added, and the reaction is carried out at 180℃ for 18h. Thioacetamide is added, and the reaction is continued for another 12h. The precipitate is filtered out and dried to obtain In2S3 nanospheres. The In2S3 nanospheres are dispersed in CdCl2·2.5H2O, heated and stirred at 60℃ for 300s, centrifuged and dried to obtain In2S3@CdIn2S4 composite material.

6. The preparation method according to claim 4, characterized in that, The preparation process of HOF-on-MOF composite material is as follows: tannic acid-treated MOF material is added to ethanol and stirred to obtain solution C; DMF is added to 1,3,6,8-tetra(4-carboxyphenyl)pyrene to dissolve it to obtain solution D; solution C and solution D are mixed and stirred at 80℃ for 4 hours, the precipitate is collected by centrifugation, washed and dried to obtain HOF-on-MOF composite material.

7. The preparation method according to claim 6, characterized in that, The preparation process of the MOF material is as follows: Zn(NO3)2·6H2O is dissolved in methanol to form a homogeneous solution A, and 2-methylimidazole is dissolved in methanol to form a homogeneous solution B; solution A and solution B are mixed under stirring to form a mixed solution, and allowed to stand for 12 hours; the precipitate is collected by centrifugation, washed and dried to obtain the MOF material.

8. The preparation method according to claim 7, characterized in that, The tannic acid treatment process is as follows: tannic acid is added to a methanol solution to obtain a methanol solution of tannic acid, MOF material is poured into the methanol solution of tannic acid to obtain a suspension, stirred for 30 minutes, centrifuged, washed, and dried to obtain the tannic acid-treated MOF material.

9. The application of the self-powered sensor according to any one of claims 1-3 in detecting ENR, characterized in that, The process includes the following steps: ENR test solutions of different concentration gradients are dropped onto an Apt / HOF-on-MOF / ITO photocathode and incubated to obtain a modified electrode labeled ENR / Apt / HOF-on-MOF / ITO; using ENR / Apt / HOF-on-MOF / ITO as the photocathode for photoelectrochemical testing, In2S3@CdIn2S4 / ITO as the photoanode, and PBS buffer solution as the electrolyte, a self-powered sensor is formed. A xenon lamp source is used to vertically irradiate the two electrodes, and the photocurrent of the self-powered sensor is measured. The photocurrent value after adding ENR is substituted into the linear regression equation of a standard curve plotted as photocurrent versus concentration to calculate the concentration of ENR in the test solution.

10. The application of the self-powered sensor according to claim 9 in detecting ENR, characterized in that: The incubation temperature was 37℃, and the incubation time was 40 minutes; the power of the xenon lamp was 300W.

Images