Organic photoelectrochemical transistor for detecting organic pesticide as well as preparation method and application of organic photoelectrochemical transistor
An organic photoelectrochemical transistor constructed by in situ hydrothermal synthesis of indium-based bimetallic sulfide heterojunction materials and aptamers solves the complexity and low sensitivity problems of organic pesticide detection in water bodies and realizes efficient and simple pesticide residue detection.
Patent Information
- Application Number
- CN202510886677.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-10-03
AI Technical Summary
The existing methods for detecting organic pesticides in water bodies are complex and time-consuming, or have low detection sensitivity, making it difficult to achieve efficient and simple pesticide residue detection.
Indium-based bimetallic sulfide heterojunction CdS/CdIn2S4 material was synthesized by in situ hydrothermal method, and combined with chitosan and diazinon aptamer to construct an organic photoelectrochemical transistor to detect organic pesticides through photoelectrochemical response.
It has achieved highly sensitive detection of organic pesticides in aquatic environments, and has the characteristics of high sensitivity, easy integration, low cost, and miniaturization, which is in line with the ecological concept of energy conservation and environmental protection.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of pesticide detection, and in particular to an organic photoelectrochemical transistor for detecting organic pesticides, and a preparation method and application thereof. Background Art
[0002] Organic pesticides (such as organophosphorus) degrade slowly in the natural environment, enter water bodies and soil through runoff and infiltration, disrupt the balance of aquatic ecosystems (such as fish deaths and algae blooms), and accumulate along the food chain, posing risks to human health. For example, they inhibit cholinesterase activity, leading to nerve conduction disorders (such as diazinon exposure causing breathing difficulties and muscle spasms) causing acute toxicity, or long-term low-dose exposure inducing cancer, reproductive disorders, immune system damage, etc., posing chronic hazards.
[0003] Among the relevant technologies, the detection methods for organic pesticides in water bodies are mainly chromatography-mass spectrometry (GC-MS / LC-MS) and enzyme-linked immunosorbent assay (ELISA). The former is complicated to operate, relies on large equipment, requires complex pretreatment (extraction and purification), and is time-consuming; although the latter is easy to operate, it has low detection sensitivity. Summary of the Invention
[0004] In order to solve or partially solve the problems existing in the related art, the present invention provides an OPECT for detecting organic pesticides and a preparation method and application thereof.
[0005] The present invention provides a method for preparing an organic photoelectrochemical transistor for detecting organic pesticides, which comprises the following steps:
[0006] Step 1), dissolving thioacetamide in a bimetallic salt precursor solution, and performing a hydrothermal reaction to obtain an indium-based bimetallic sulfide heterojunction CdS / CdIn2S4; the bimetallic salt precursor solution includes: Cd 2+ The first metal salt can provide In 3+ a second metal salt of;
[0007] Step 2), dispersing the naphthol solution and the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in deionized water to obtain a suspension, applying the suspension to the surface of ITO conductive glass, and drying to obtain a photogate CdS / CdIn2S4-ITO;
[0008] Step 3), drop-coating the chitosan solution on the surface of the photogate CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / CdS / CdIn2S4-ITO; drop-coating the glutaraldehyde solution on the surface of the photogate CS / CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / GA / CdS / CdIn2S4-ITO;
[0009] Step 4), the diazinon aptamer solution is drop-coated on the surface of the photogate CS / GA / CdS / CdIn2S4-ITO, and after incubation at room temperature, an electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO is obtained, which is an organic photoelectrochemical transistor for detecting organic pesticides.
[0010] Furthermore, in step 1), the first metal salt is selected from cadmium chloride hydrate or cadmium nitrate hydrate; the second metal salt is selected from indium chloride hydrate or indium nitrate hydrate; and the molar ratio of the first metal salt, the second metal salt and thioacetamide is (0.1-3): (0.05-1.5): (0.5-15).
[0011] Furthermore, in step 1), the temperature of the hydrothermal reaction is 100-200° C., and the time is 5-16 hours.
[0012] Furthermore, in step 2), the concentration of the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in the suspension is 1.0-5.0 mg / mL, and the drop coating density on the ITO conductive glass surface is 50-100 μL / cm 2 .
[0013] Furthermore, in step 3), the concentration of the chitosan solution is 5-15 mg / ml, and the drop coating density of the chitosan solution is 10-30 μL / cm 2 .
[0014] Furthermore, in step 3), the concentration of the glutaraldehyde solution is 3-7.5 mg / ml, and the drop coating density of the chitosan solution is 10-30 μL / cm 2 .
[0015] Furthermore, in step 4), the concentration of the diazinon aptamer solution is 0.1-5 μmol / L, and the drop coating density is 10-30 μL / cm 2 .
[0016] Furthermore, the sequence number of the diazinon aptamer is: 5'-ATCCgTCACACCTgCTCTAATATAgAggTATTgCTCTTggACAAggTACAgg gATggTgTTggCTCCCgTAT-3'.
[0017] The present invention also provides an organic photoelectrochemical transistor for detecting organic pesticides, which is prepared according to any one of the methods described above.
[0018] The present invention also provides an application of the above-mentioned organic photoelectrochemical transistor in detecting organic pesticide residues in a water environment.
[0019] The organic photoelectrochemical transistor (OPECT) for detecting organic pesticides provided by the present invention and its preparation method have the following advantages:
[0020] 1. This preparation method uses an in-situ hydrothermal method to synthesize CdS / CdIn2S4 heterojunction material. The heterostructure effectively promotes the separation of photogenerated charge carriers, significantly enhancing the photocurrent response. The tightly coupled heterojunction interface further reduces the probability of charge recombination, significantly improving the charge separation efficiency. Experiments have demonstrated that this material has excellent optoelectronic properties, and the constructed sensing system has high sensitivity for organic pesticide detection.
[0021] 2. OPECT aptamer sensors are constructed by combining organic pesticide aptamers and indium-based bimetallic sulfide heterojunction materials to achieve highly sensitive detection of organic pesticides in aquatic environments, broadening the practical application of organic photoelectrochemical transistor sensors in the field of pesticide detection.
[0022] 3. The OPECT has the characteristics of high sensitivity, easy integration, portability, low cost and miniaturization, which conforms to the concept of energy conservation and environmental protection.
[0023] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.
[0025] Figure 1 2 are X-ray diffraction (XRD) patterns of CdS / CdIn2S4, CdS and CdIn2S4 in the embodiments of the present invention.
[0026] Figure 2 The transmission electron microscopy (TEM) image of CdIn2S4, as well as the TEM image and high-magnification transmission electron microscopy (HRTEM) image of CdS / CdIn2S4 in the embodiment of the present invention are shown.
[0027] Figure 3 This is an X-ray photoelectron spectroscopy (XPS) diagram of CdS / CdIn2S4 in an embodiment of the present invention.
[0028] Figure 4 These are the solid ultraviolet diffuse reflectance (DRS) graphs of CdS / CdIn2S4, CdS and CdIn2S4 in the embodiments of the present invention.
[0029] Figure 5These are the photocurrent diagrams and electrochemical impedance spectroscopy (EIS) diagrams of CdS / CdIn2S4 and CdIn2S4 in the embodiments of the present invention.
[0030] Figure 6 This is a rate diagram of CdS / CdIn2S4 in an embodiment of the present invention.
[0031] Figure 7 The present invention is similar to the channel current (I D )picture.
[0032] Figure 8 The detection results of diazinon by Apt / CS / GA / CdS / CdIn2S4-ITO in the embodiment of the present invention are shown in FIG. D Response graph, where a is the I obtained by detecting different concentrations of DZN D Figure 2, b shows the plotted diazinon concentration-I D Linear relationship graph.
[0033] Figure 9 Figure 2 shows the selectivity (a), stability (b) and repeatability (c) of Apt / CS / GA / CdS / CdIn2S4-ITO in detecting diazinon in an embodiment of the present invention. DETAILED DESCRIPTION
[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0035] The terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The singular forms "a," "the," and "the" used in this invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.
[0036] It should be understood that although the terms "first", "second", "third", etc. may be used to describe various information in the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.
[0037] Organic photoelectrochemical transistor (OPECT) sensors are a new class of electrochemical sensing devices developed based on the correlation between the conversion of changes in target analyte concentration into changes in power signals (e.g., gate current, channel current, etc.). OPECT sensors combine OECT and PEC sensing technologies, using the PEC working electrode as the OECT gate, and have shown great potential for sensitive detection of chemical and biological species. Compared to traditional PEC biosensors, OPECT sensors are characterized by their inherent signal amplification capabilities, which significantly improves sensor sensitivity. Compared to OECTs, OPECT sensors combine the advantages of PECs' separation of the excitation source and signal detection systems, reducing background signals and eliminating the need for an external gate voltage, thus eliminating the need for additional voltages and reducing power consumption. Given their advantages such as low cost, zero gate voltage, mechanical flexibility, and biocompatibility, OPECTs are currently widely used in diverse biosensing fields, such as enzyme sensing, DNA detection, immunoassays, and cell analysis.
[0038] Therefore, the inventors of this application considered applying OPECT to the detection of organic pesticides in the environment. Designing a photoactive gate electrode with high optical performance, high OPECT efficiency, and stability is key to constructing an OPECT sensor for organic pesticides in the environment. The inventors of this application first considered using metal sulfides, which are important photoelectrochemical materials due to their excellent light absorption, structural, and optical properties. Heterojunction materials with grating structures are composed of two or more semiconductors. These heterojunction grating materials can regulate the interface band alignment and strong charge separation, thereby achieving better photoelectric performance than single semiconductor materials. The inventors subsequently discovered that multimetallic sulfide grating materials offer advantages such as good chemical stability, excellent band tunability, and a rich elemental composition, showing promising prospects for better photoelectric performance than traditional binary metal sulfides. In particular, directly constructing a metal sulfide heterojunction in situ can achieve good lattice matching, promote continuous band alignment, and effectively eliminate interfacial impedance. This approach enhances charge transfer and suppresses the recombination of photogenerated electron-hole pairs, significantly improving the efficiency and stability of charge separation and transport. Finally, an indium-based bimetallic sulfide material was prepared as a photoactive gate electrode, and the organic pesticide aptamer and indium-based bimetallic sulfide heterojunction material were further combined to construct an OPECT aptamer sensor, thereby realizing rapid and highly sensitive detection of organic pesticides.
[0039] Based on the above inventive concept, an embodiment of the present invention provides a method for preparing an organic photoelectrochemical transistor (OPECT) for detecting organic pesticides, which comprises the following steps:
[0040] Step 1), dissolving thioacetamide in a bimetallic salt precursor solution, and performing a hydrothermal reaction to obtain an indium-based bimetallic sulfide heterojunction CdS / CdIn2S4; the bimetallic salt precursor solution includes: Cd 2+ The first metal salt can provide In 3+ a second metal salt of;
[0041] Step 2), dispersing the naphthol solution and the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in deionized water to obtain a suspension, applying the suspension to the surface of ITO conductive glass, and drying to obtain a photogate CdS / CdIn2S4-ITO;
[0042] Step 3), drop-coating the chitosan solution on the surface of the photogate CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / CdS / CdIn2S4-ITO; drop-coating the glutaraldehyde solution on the surface of the photogate CS / CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / GA / CdS / CdIn2S4-ITO;
[0043] Step 4), the diazinon aptamer solution is drop-coated on the surface of the photogate CS / GA / CdS / CdIn2S4-ITO, and after incubation at room temperature, the electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO is obtained, that is, OPECT for detecting organic pesticides.
[0044] In the preparation method provided in this embodiment, step 1) is the step of preparing the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4. In this step, the bimetallic salt precursor solution is used to provide a bimetallic ion source (the first metal salt provides Cd 2+ and the second metal salt provides In 3+ ); Thioacetamide provides S as a sulfur source 2+ Thioacetamide (CH3CSNH2, TAA) is hydrolyzed under heating conditions to release S 2 -ion. Cd 2+ 、In 3+ With S 2 -combined to form sulfide precipitation and formed an interface-coupled heterostructure CdS / CdIn2S4 through in situ growth.
[0045] The solvent for the bimetallic salt precursor solution is preferably a mixed solution of ethylene glycol and ethanol. The high-boiling point solvent ethylene glycol helps prolong the reaction time and promote slow crystal growth, while ethanol helps reduce surface tension and inhibit particle agglomeration. The volume ratio of ethanol to ethylene glycol in the solvent is preferably 1:1-3, and most preferably 1:2.5. The first metal salt is preferably selected from cadmium chloride hydrate or cadmium nitrate hydrate; the second metal salt is preferably selected from indium chloride hydrate or indium nitrate hydrate. The molar ratio of the first metal salt, the second metal salt, and thioacetamide is (0.1-3):(0.05-1.5):(0.5-15), more preferably (0.6-1.2):(0.3-0.8):(4-7), and most preferably 1:0.5:5. The concentration of the first metal salt in the bimetallic salt precursor solution is preferably 0.03-1 mol / L, more preferably 0.2-0.5 mol / L, and most preferably 0.33 mol / L.
[0046] The hydrothermal reaction temperature in this step is preferably 100-200°C, and the reaction time is preferably 5-16 hours, more preferably 160-200°C, and the reaction time is 8-16 hours. Those skilled in the art will appreciate that the hydrothermal reaction is carried out in a closed environment. After the reaction is completed, the resulting mixture is naturally cooled to room temperature, and then centrifuged, washed, and vacuum-dried to obtain the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4. The washing process can be performed by washing with water and alcohol several times.
[0047] Step 2) is a step of fixing the CdS / CdIn2S4 heterojunction material on the surface of the ITO conductive glass by solution drop coating to form a gate electrode with a light-responsive function. It is to first prepare a CdS / CdIn2S4 / naphthol suspension. The dispersion in this step is preferably ultrasonic dispersion, and the cavitation effect is used to destroy the particle agglomeration. The concentration of the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in the suspension is preferably 1.0-5.0 mg / mL, and the drop coating density on the ITO conductive glass surface is preferably 50-100 μL / cm 2 In the suspension, naphthol acts as a surfactant. Its hydrophobic naphthalene ring adsorbs onto the sulfide surface, while the hydrophilic -OH group hydrogen bonds with water molecules, promoting uniform dispersion of CdS / CdIn2S4 in water. The concentration of naphthol is preferably 0.03-0.06 mg / mL, and most preferably 0.04 mg / mL. After coating, the substrate is dried naturally, preferably rinsed with deionized water, and then air-dried to obtain the CdS / CdIn2S4-ITO photogate.
[0048] The above-mentioned ITO conductive glass is preferably pretreated as follows: the ITO conductive glass is sequentially washed with water, alcohol and water; then the ITO conductive glass is boiled in alkaline solution, and finally washed with deionized water and blown dry to obtain the pretreated ITO conductive glass.
[0049] Step 3) involves modifying the surface of the base CdS / CdIn2S4-ITO photogate to form a chitosan (CS)-glutaraldehyde (GA) crosslinking system. This system is used to construct a three-dimensional network structure on the photogate surface, providing active sites for subsequent aptamer immobilization. Specifically, CS is first immobilized on the CdS / CdIn2S4-ITO surface using a solution drop coating method. CS forms a monolayer on the electrode surface through electrostatic adsorption and hydrogen bonding, resulting in the photogate CS / CdS / CdIn2S4-ITO. GA is then introduced onto the CS / CdS / CdIn2S4-ITO surface using a solution drop coating method. CS and GA crosslink to form a porous gel layer, resulting in the photogate CS / GA / CdS / CdIn2S4-ITO. This modified CS / GA layer on the photogate surface provides chemical anchoring sites for subsequent aptamer immobilization and exhibits excellent biocompatibility, reducing nonspecific adsorption.
[0050] The concentration of the chitosan solution is preferably 5-15 mg / mL, and the drop coating density of the chitosan solution is preferably 10-30 μL / cm 2 More preferably, the concentration of the chitosan solution is preferably 10 mg / mL, and the drop coating density of the chitosan solution is preferably 10 μL / cm 2 The concentration of the glutaraldehyde solution is preferably 3-7.5 mg / mL, and the drop coating density of the chitosan solution is preferably 10-30 μL / cm 2More preferably, the concentration of the glutaraldehyde solution is 5.3 mg / mL, and the drop density of the chitosan solution is 10 μL / cm 2 .
[0051] In this step, the chitosan solution is preferably dried at room temperature after drop coating, preferably for 1-2 hours, then rinsed with phosphate buffer solution, and then dried again to obtain the CS / CdS / CdIn2S4-ITO photogate. The glutaraldehyde solution is also preferably dried at room temperature after drop coating, preferably for 1-2 hours, then rinsed with phosphate buffer solution, and then dried again to obtain the CS / GA / CdS / CdIn2S4-ITO photogate.
[0052] In step 4), the diazinon aptamer (Apt) is immobilized on the CS / GA modified photogate surface by directional covalent coupling using a drop coating method, forming a biosensor interface that can specifically capture the target molecule, diazinon (DZN). The concentration of the diazinon aptamer solution is preferably 0.1 to 5 μmol / L, and the drop coating density is preferably 10 to 30 μL / cm 2 More preferably, the concentration of the diazinon aptamer solution is 1-2 μmol / L, and the drop coating density is 10 μL / cm 2 The incubation time at room temperature is preferably 6 to 18 hours, more preferably 8 to 12 hours. After incubation, the electrode is preferably rinsed with a phosphate buffer solution to remove any unanchored aptamers on the electrode surface, and then air-dried at room temperature to obtain the electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO. The sequence number of the diazinon aptamer Apt is preferably 5'-ATCCgTCACACCTgCTCTAATATAgAggTATTgCTCTTggACAAggTACAgg gATggTgTTggCTCCCgTAT-3'.
[0053] In the above steps, the concentration of the phosphate buffer solution used is preferably 0.1 M, and the pH value is preferably 7.0.
[0054] Another embodiment of the present invention further provides an OPECT for detecting organic pesticides, which is prepared according to the method of the above embodiment, and the specific implementation method is not repeated here.
[0055] Another embodiment of the present invention further provides an application of the above-mentioned OPECT for detecting organic pesticide residues in a water environment. The specific steps are preferably as follows:
[0056] Step S1: Standard curve establishment
[0057] A standard solution droplet of known DZN concentration was applied to the surface of the electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO, and dried naturally at room temperature. After rinsing with phosphate buffer solution, the standard electrode DZN / Apt / CS / GA / CdS / CdIn2S4-ITO was obtained.
[0058] The standard electrode DZN / Apt / CS / GA / CdS / CdIn2S4-ITO was used as a photogate, connected to the source and drain of an organic electrochemical transistor, and a phosphate buffer solution was used as an electrolyte. The channel current-time (I D -t) curve; using DZN concentration and corresponding I D The standard curve of DZN was obtained by the linear relationship;
[0059] Step S2: Determine the DZN concentration in the test solution
[0060] A drop of the test liquid was applied to the surface of the electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO, dried naturally at room temperature, rinsed with phosphate buffer solution, and dried at room temperature to obtain the electrode to be tested DZN / Apt / CS / GA / CdS / CdIn2S4-ITO;
[0061] The electrode to be tested, DZN / Apt / CS / GA / CdS / CdIn2S4-ITO, was used as a photogate, connected to the source and drain of an organic electrochemical transistor, and a phosphate buffer solution was used as an electrolyte. The channel current-time (I D -t) curve; D Substitute the standard curve into the calculated concentration of DZN in the test solution.
[0062] Preferably, the amount of DZN standard solution in step S1 is 10-20 μL, and the concentration is 0.2-1.96×10 7 pg L -1 In step 2, the amount of the test solution to be applied is preferably 10 to 20 μL. In steps S1 and S2, the phosphate buffer solution is prepared by mixing 0.1 M sodium dihydrogen phosphate and disodium hydrogen phosphate to adjust the pH to 7.0, and the concentration is 0.1 M.
[0063] The OPECT for detecting organic pesticides and the preparation method thereof provided in the embodiments of the present invention have the following advantages:
[0064] 1. This preparation method synthesizes CdS / CdIn2S4 heterojunction materials via an in-situ hydrothermal method. The heterojunction structure effectively promotes the separation of photogenerated charge carriers, significantly enhancing the photocurrent response. The tightly coupled heterojunction interface further reduces the probability of charge recombination, significantly improving the charge separation efficiency. Experiments have demonstrated that this material has excellent optoelectronic properties, and the constructed sensing system has high sensitivity for organic pesticide detection.
[0065] 2. OPECT aptamer sensors are constructed by combining organic pesticide aptamers and indium-based bimetallic sulfide heterojunction materials to achieve highly sensitive detection of organic pesticides in aquatic environments, broadening the practical application of organic photoelectrochemical transistor sensors in the field of pesticide detection.
[0066] 3. The OPECT has the characteristics of high sensitivity, easy integration, portability, low cost and miniaturization, which conforms to the concept of energy conservation and environmental protection.
[0067] The technical solution of the present invention will be further described below in conjunction with specific embodiments:
[0068] Example 1 Preparation of Photoelectrochemical Aptamer Electrode Sensor Apt / CS / GA / CdS / CdIn2S4-ITO
[0069] (1) Preparation of indium-based bimetallic sulfide heterojunction CdS / CdIn2S4:
[0070] Dissolve 1 mmol of cadmium nitrate tetrahydrate and 0.5 mmol of indium nitrate tetrahydrate in a mixture of 25 mL of ethylene glycol and 10 mL of ethanol, and stir vigorously for 30 minutes to obtain solution A. Weigh 5 mmol of thioacetamide and dissolve it in solution A, and continue stirring for 1 hour to obtain solution B.
[0071] Solution B was transferred to a 100 mL polytetrafluoroethylene-lined reactor and heated in an oven at 200°C for 16 hours. After cooling to room temperature, the reaction mixture was centrifuged, washed three times with deionized water and three times with ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain an indium-based bimetallic sulfide heterojunction CdS / CdIn2S4.
[0072] (2) Preparation of CdS / CdIn2S4-ITO photogate:
[0073] Pre-treat the ITO conductive glass: ultrasonically clean the ITO conductive glass in deionized water and ethanol for half an hour, followed by multiple rinses with deionized water. The conductive glass is then placed in a 0.1 mol / L NaOH aqueous solution, boiled for 30 minutes, rinsed with deionized water, and dried.
[0074] A mixed aqueous solution of CdS / CdIn2S4 and naphthol was prepared, with a CdS / CdIn2S4 concentration of 1 mg / mL and a naphthol concentration of 0.04 mg / ml. The solution was placed in an ultrasonic machine for ultrasonic dispersion to obtain a stable suspension. Then, 50 μL of the suspension was dropwise applied to pretreated ITO conductive glass and allowed to dry naturally for 30 minutes. The resulting modified photogate was designated CdS / CdIn2S4-ITO.
[0075] (3) Preparation of photogate CS / CdS / CdIn2S4-ITO:
[0076] 10 μL of chitosan (CS) solution (concentration of 10 mg / ml) was transferred with a pipette and drop-coated on the surface of the CdS / CdIn2S4-ITO electrode. The solution was dried at room temperature for 1 h and rinsed with phosphate buffer solution. The modified photogate obtained after drying was designated as CS / CdS / CdIn2S4-ITO.
[0077] (4) Preparation of photogate CS / GA / CdS / CdIn2S4-ITO:
[0078] 10 μL of glutaraldehyde (GA) solution (concentration of 5.3 mg / ml) was transferred with a pipette and drop-coated on the surface of the CS / CdS / CdIn2S4-ITO electrode. The solution was dried at room temperature for 1 hour and rinsed with phosphate buffer solution. The modified photogate obtained after drying was designated as CS / GA / CdS / CdIn2S4-ITO.
[0079] (5) Preparation of photoelectrochemical aptamer sensor:
[0080] 10 μL of diazinon (DZN) aptamer (concentration of 1.5 μmol / L, 10 μL) was transferred with a pipette and drop-coated on the surface of the CS / GA / CdS / CdIn2S4-ITO photogate. The mixture was incubated at room temperature for 10 h, rinsed with phosphate buffer solution, and dried at room temperature to obtain a photoelectrochemical aptamer sensor, which was recorded as Apt / CS / GA / CdS / CdIn2S4-ITO.
[0081] Comparative Example 1 Preparation of CdS
[0082] Dissolve 1 mmol of cadmium nitrate tetrahydrate in a mixture of 25 mL of ethylene glycol and 10 mL of ethanol, and stir vigorously for 30 min to obtain solution A.
[0083] Weigh 5 mmol of thioacetamide and dissolve it in solution A. Continue stirring for 1 h to obtain solution B.
[0084] Solution B was transferred to a 100 mL polytetrafluoroethylene-lined reactor and heated in an oven at 200°C for 16 hours. After cooling to room temperature, the resulting mixture was centrifuged, washed three times with deionized water and three times with ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain CdS.
[0085] Comparative Example 2 Preparation of CdIn2S4
[0086] 1 mmol of cadmium nitrate tetrahydrate and 2 mmol of indium nitrate tetrahydrate were dissolved in a mixed solution of 25 mL of ethylene glycol and 10 mL of ethanol, and stirred vigorously for 30 min to obtain solution A;
[0087] Weigh 5 mmol of thioacetamide and dissolve it in solution A. Continue stirring for 1 h to obtain solution B.
[0088] Solution B was transferred to a 100 mL polytetrafluoroethylene-lined reactor and heated in an oven at 200°C for 16 hours. After cooling to room temperature, the resulting mixture was centrifuged, washed three times with deionized water and three times with ethanol, and dried in a vacuum oven at 60°C for 12 hours to obtain CdIn2S4.
[0089] The X-ray diffraction (XRD) patterns of CdS / CdIn2S4 prepared in Example 1, CdS prepared in Comparative Example 1 and CdIn2S4 prepared in Comparative Example 2 are shown in FIG. Figure 1 As shown, Figure 1 In the equation, a is CdIn2S4, b is CdS, and c is CdS / CdIn2S4. Figure 1 a shows that the typical diffraction peaks of CdIn2S4 are located at 2θ=27.3 and 47.5°, corresponding to the (311) and (440) planes of the CdIn2S4 sample, respectively, which are consistent with the cubic spinel structure of CdIn2S4 (JCPDS no.27-0060). Figure 1 The main diffraction peaks in b also correspond to (JCPDS no.41-1049). Figure 1 In Figure c, the diffraction peaks of CdIn2S4 and CdS can be observed simultaneously. The XRD results confirm the successful synthesis of CdS / CdIn2S4 composite materials.
[0090] The transmission electron microscope (TEM) image of CdIn2S4 prepared in Comparative Example 2 is as follows Figure 2 As shown in a, the TEM image and high magnification transmission electron microscope (HRTEM) image of CdS / CdIn2S4 prepared in Example 1 are shown in FIG. Figure 2 As shown in b and c. Figure 2 As shown in a, pure CdIn2S4 consists of spherical particles of uniform size, with smooth surfaces and obvious aggregation between particles ( Figure 2a). After the introduction of CdS, the composite material still exhibits a certain degree of aggregation ( Figure 2 b). The aggregation phenomenon in CdS / CdIn2S4 is significantly reduced, indicating that the addition of CdS effectively inhibits the aggregation behavior of CdIn2S4, which is originally tightly packed. High-resolution transmission electron microscopy (HRTEM) images clearly show ( Figure 2 c) Clearly showing lattice fringes with spacings of 0.334 nm and 0.323 nm, corresponding to the (311) planes of CdIn2S4 and the (101) planes of CdS, respectively. The interlaced lattices of CdS and CdIn2S4 confirm the presence of a heterostructure, and their interlaced lattices also confirm the close contact of the heterostructure.
[0091] The X-ray photoelectron spectroscopy (XPS) of CdS / CdIn2S4 prepared in Example 1 is shown in FIG. Figure 3 As shown, Figure 3 In the figure, ac are high-resolution spectra of Cd 3d, In 3d, and S2p, respectively. Figure 3 a It can be seen that the peaks at 405.45 and 412.20 eV correspond to Cd 3d 5 / 2 and Cd 3d 3 / 2 , indicating that the oxidation state of Cd ions is +2. Figure 3 b can be seen that In 3d 5 / 2 and In 3d 3 / 2 The binding energies of In are 445.15eV and 452.70eV respectively, and In exists in the +3 valence state. Figure 3 c It can be seen that the peaks at 161.85 and 163.0 eV belong to S2p 3 / 2 and S2p 1 / The oxidation state of S is -2. The binding energies of Cd, In, and S in CdS / CdIn2S4 all shift slightly toward higher energies due to the support of CdS. This slight positive shift is primarily due to electronic interactions between CdIn2S4 and CdS, indicating that CdIn2S4 tends to lose electrons and transfer them to CdS. XPS results further demonstrate the successful preparation of the CdS / CdIn2S4 composite material.
[0092] The solid ultraviolet diffuse reflectance (DRS) graphs of CdS / CdIn2S4 prepared in Example 1, CdS prepared in Comparative Example 1 and CdIn2S4 prepared in Comparative Example 2 are as follows: Figure 4 shown. Figure 4In the figure, a represents CdIn2S4, b represents CdS, and c represents CdS / CdIn2S4. As shown in the figure, CdIn2S4 exhibits superior visible light absorption compared to CdS, while CdS has stronger UV absorption. By constructing a CdS / CdIn2S4 heterojunction composite, the resulting material not only retains the outstanding UV absorption properties of CdS but also exhibits the visible light responsiveness derived from the CdIn2S4 component. Furthermore, the CdS / CdIn2S4 heterostructure further facilitates carrier excitation, enhancing photoelectric conversion efficiency.
[0093] In order to explore the charge separation behavior of the samples and clarify the mechanism of enhanced photoelectric performance in CdS / CdIn2S4 composite materials, the photoelectric performance of CdIn2S4 and CdS / CdIn2S4 was tested. The photoelectrochemical detection method and conditions are as follows:
[0094] The electrochemical tests were all performed on a CHI660E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.), and the excitation light source was a 300W xenon lamp (PLS-SXE300, Beijing Bofeilai Technology Co., Ltd.). The photoelectric performance test used a traditional three-electrode system: a modified electrode (CdIn2S4 or CdS / CdIn2S4) as the working electrode, a platinum wire electrode as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. The photocurrent tests were all performed at room temperature in a phosphate buffer solution (0.1 mol / L, pH = 7.0) without applying any bias. Electrochemical impedance spectroscopy (EIS) was performed in a solution containing 5 mmol / L Fe(CN)6 3- / 4- The experiment was carried out in a phosphate buffer solution (0.1 mol / L, pH=7.0) containing 0.1 mol / L KCl, with a frequency range of 0.01 Hz to 10 kHz, an initial potential of 0.24 V, and an AC amplitude of 5 mV.
[0095] The photocurrent and electrochemical impedance spectroscopy (EIS) diagrams of CdS / CdIn2S4 prepared in Example 1 and CdIn2S4 prepared in Comparative Example 2 are shown in FIG. Figure 5 As shown, Figure 5 A is the photocurrent diagram, and B is the EIS diagram. In the figure, a is CdIn2S4, and b is CdS / CdIn2S4. Figure 5 As shown in Figure a, all synthesized samples exhibited good photocurrent responses. Furthermore, the photocurrent response of CdS / CdIn2S4 was approximately twice that of CdIn2S4, indicating that the heterojunction formed after the introduction of CdS exhibits rapid carrier separation. Electron emission characteristics (EIS) testing further investigated the electron transfer capability of the composite material, indicating that a smaller radius indicates a stronger electron transfer capability. Compared to CdIn2S4, the CdS / CdIn2S4 sample exhibited a smaller arc radius in the dark, indicating that the heterojunction exhibits rapid electron transfer efficiency, thereby enhancing photoelectrochemical performance.
[0096] Figure 6 This is the rate diagram of CdS / CdIn2S4 prepared in Example 1. Figure 6 It can be seen that the current gain of the system after lighting (ΔI D / ΔI G ) more than 10 4 , demonstrating its superior efficiency in amplifying small gate current changes. This photoresponsive behavior can be attributed to the modulation of channel conductance, which generates a voltage across the photogate and drives ion migration. These results suggest that the composite material is promising for constructing organic photoelectrochemical transistor-based aptamer sensors and achieving efficient DZN detection.
[0097] Based on this, a sensor was constructed and I D For testing, see Figure 7 , Figure 7 The channel current (ID) diagram of different sensors, Figure 7 a is CdS / CdIn2S4-ITO, b is CS / CdS / CdIn2S4-ITO, c is CS / GA / CdS / CdIn2S4-ITO, d is Apt / CS / GA / CdS / CdIn2S4-ITO, and e is DZN / Apt / CS / GA / CdS / CdIn2S4-ITO (10 μL, concentration 1.96 pg L -1 The DZN solution was applied on the surface of the Apt / CS / GA / CdS / CdIn2S4-ITO electrode, dried naturally at room temperature, rinsed with phosphate buffer solution, and dried at room temperature to obtain the product). Figure 7 Shows the different I under corresponding illumination D . I of CdS / CdIn2S4-ITO gate D It is about 54.07mA (curve a). After CS, GA and aptamer are modified in sequence, its I D When the sensor was incubated with DZN, I D It increases slightly (curve f).
[0098] 0.196 pg L -1 , 1.96 pg L -1 、19.6pg L -1 , 0.196ng L -1 , 1.96ng L -1 、19.6ngL -1 , 0.196 μg L -1 , 1.96 μg L -1 , 19.6 μg L-1 A DZN standard solution of equal concentration was dropwise applied to the surface of the electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO prepared in Example 1, and the solution was naturally dried at room temperature. After rinsing with a phosphate buffer solution, the solution was air-dried at room temperature to obtain a standard electrode DZN / Apt / CS / GA / CdS / CdIn2S4-ITO. The standard electrode DZN / Apt / CS / GA / CdS / CdIn2S4-ITO was used as a photogate to connect the source and drain of an organic electrochemical transistor. A phosphate buffer solution was used as an electrolyte. The channel current-time (I) of the OPECT sensor was obtained under a preset bias voltage. D -t) curve. Figure 8 I for Apt / CS / GA / CdS / CdIn2S4-ITO detection of DZN D Response diagram, where a is the channel current diagram obtained by detecting different concentrations of DZN, and b is the linear relationship diagram of the DZN concentration logarithm-channel current. Figure 8 a It can be seen that with the increase of DZN concentration, the I D The signal gradually increases. And there is a certain linear relationship between the logarithm of DZN concentration and the response signal ( Figure 8 b), linear range: 0.2 pg L -1 ~19.6 μg L -1 , the linear equation is I D / I0=0.1803-0.0859log(C DZN / pg L -1 )(R 2 =0.993), and the detection limit was as low as 0.067 pg L -1 .
[0099] Figure 9 Figure 3 shows the selectivity (a), stability (b), and reproducibility (c) of Apt / CS / GA / CdS / CdIn2S4-ITO for detecting DZN. The selectivity of the constructed OPECT sensor for detecting DZN target molecules was investigated using omethoate (OMT), glufosinate ammonium (GLA), edifenthal (EDF), imidacloprid (IMI), and atrazine (ATZ) as interfering species. The specific method is as follows: First, the aptamer was optimized (0.3 μM, 10 h incubation) and the aptamer was measured at 10 μM and 19.6 pg L -1 The standard response signal of DZN was obtained, and then the concentration of (1960 pg L -1 ) of each interferer and record the channel current of the sensor (I D Selectivity was assessed by comparing the rate of signal change before and after the addition of interfering substances.
[0100] Figure 9 Figure a shows that in the presence of the DZN aptamer, the sensor's photocurrent response caused by interfering species is essentially negligible. Thanks to the specific recognition between the DZN aptamer and DZN, the sensor exhibits a significant change in channel current in response to DZN, demonstrating its strong anti-interference capability. After 1000 seconds of on-off light irradiation, the sensor's photocurrent stabilizes, demonstrating the sensor's excellent stability in detecting DZN. Figure 9 b) At the same time, 5 identical Apt / CS / GA / CdS / CdIn2S4-ITO electrodes were prepared to evaluate the reproducibility of the DZN test. Figure 9 As can be seen in Figure c, the constructed sensor exhibits good reproducibility, with a relative standard deviation (RSD) of 2.228%.
[0101] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A method for preparing an organic photoelectrochemical transistor for detecting organic pesticides, characterized in that: It includes the following steps: Step 1), dissolving thioacetamide in a bimetallic salt precursor solution, and performing a hydrothermal reaction to obtain an indium-based bimetallic sulfide heterojunction CdS / CdIn2S4; the bimetallic salt precursor solution includes: Cd 2+ The first metal salt can provide In 3+ a second metal salt of; Step 2), dispersing the naphthol solution and the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in deionized water to obtain a suspension, applying the suspension to the surface of ITO conductive glass, and drying to obtain a photogate CdS / CdIn2S4-ITO; Step 3), drop-coating the chitosan solution on the surface of the photogate CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / CdS / CdIn2S4-ITO; drop-coating the glutaraldehyde solution on the surface of the photogate CS / CdS / CdIn2S4-ITO, and drying to obtain the photogate CS / GA / CdS / CdIn2S4-ITO; Step 4), the diazinon aptamer solution is drop-coated on the surface of the photogate CS / GA / CdS / CdIn2S4-ITO, and after incubation at room temperature, an electrode sensor Apt / CS / GA / CdS / CdIn2S4-ITO is obtained, which is an organic photoelectrochemical transistor for detecting organic pesticides.
2. The preparation method according to claim 1, characterized in that In the step 1), the first metal salt is selected from cadmium chloride hydrate or cadmium nitrate hydrate; the second metal salt is selected from indium chloride hydrate or indium nitrate hydrate; and the molar ratio of the first metal salt, the second metal salt and thioacetamide is (0.1-3): (0.05-1.5): (0.5-15).
3. The preparation method according to claim 1, characterized in that In the step 1), the temperature of the hydrothermal reaction is 100-200° C., and the time is 5-16 hours.
4. The preparation method according to claim 1, characterized in that In the step 2), the concentration of the indium-based bimetallic sulfide heterojunction CdS / CdIn2S4 in the suspension is 1.0-5.0 mg / mL, and the drop coating density on the ITO conductive glass surface is 50-100 μL / cm 2 .
5. The preparation method according to claim 1, characterized in that In step 3), the concentration of the chitosan solution is 5-15 mg / ml, and the drop coating density of the chitosan solution is 10-30 μL / cm 2 .
6. The preparation method according to claim 1, characterized in that In step 3), the concentration of the glutaraldehyde solution is 3-7.5 mg / ml, and the drop coating density of the chitosan solution is 10-30 μL / cm 2 .
7. The preparation method according to claim 1, characterized in that In step 4), the concentration of the diazinon aptamer solution is 0.1-5 μmol / L, and the drop coating density is 10-30 μL / cm 2 .
8. The preparation method according to claim 1, characterized in that The sequence number of the diazinon aptamer is: 5'-ATCCgTCACACCTgCTCTAATATAgAggTATTgCTCTTggACAAggTACAgg gATggTgTTggCTCCCgTAT-3'.
9. An organic photoelectrochemical transistor for detecting organic pesticides, characterized in that: It is prepared according to the method according to any one of claims 1 to 8.
10. Use of the organic photoelectrochemical transistor according to claim 9 in detecting organic pesticide residues in aquatic environments.