Application of a molecularly imprinted nanochannel membrane in selective detection of dimethoate

Abstract

The application discloses application of a molecular imprinting nanochannel membrane in selective identification of dimethoate molecules, and the molecular imprinting nanochannel membrane is obtained by first synthesizing a molecular imprinting polymer with a dimethoate molecular imprinting cavity, and then uniformly loading the molecular imprinting polymer on an AAO base by using a super assembly technology. The application constructs a nanofluid device including two half electroconductive cells by taking the molecular imprinting nanochannel membrane as an ion selective membrane, realizes identification and detection of dimethoate by testing I-V variation after adding a to-be-tested solution in an electrolyte solution, and has considerable application prospect in the field of intelligent ion transmission due to simple operation and high sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of nanochannel and pesticide detection technology, specifically, it relates to the application of a molecularly imprinted nanochannel membrane in the selective detection of dimethoate. Background Technology

[0002] Organophosphorus pesticides are organic compounds containing phosphorus, primarily used to control plant diseases, insects, and weeds. Compared to other pesticides, organophosphorus pesticides offer advantages such as high efficiency and long-lasting effects. Dimethoate (DMT), as a representative organophosphorus pesticide, has a wide range of applications. Therefore, rapid and accurate monitoring of DMT in fruits and vegetables is of significant research importance.

[0003] Ion nanochannels in biological systems play a crucial role in cellular signal transduction, energy conversion, and responses to various physiological stimuli, thereby controlling ion transmembrane transport and maintaining physiological homeostasis. Inspired by biological nanochannels, artificial ion nanochannel biosensing platforms have flourished in recent years and are widely used for the detection of proteins, nucleic acids, amino acids, tumor cells, and ions. However, with the rapid development of artificial ion nanochannels, the demand for higher precision in sensitivity and selectivity in analytical detection has increased, highlighting its limitations. Currently, the selective recognition of analytes based on artificial ion nanochannels relies on intermolecular interactions (such as covalent interactions, complexation, coordination, and redox interactions), which makes it difficult to achieve high selectivity for target analytes based on spatial configuration, shape, and size.

[0004] Molecular imprinting is a synthetic technique for obtaining molecularly imprinted polymers that perfectly match the target analyte in terms of spatial shape, size, and functional groups, and can accurately identify the chemical bonds and spatial configuration of the target analyte in complex environments. Its principle is figuratively described as the "lock-and-key principle." Introducing molecular imprinting into nanochannels can effectively improve the selectivity of nanochannel detection. It not only enables the identification of the target analyte's chemical bonds but also allows for precise identification of the target molecule's configuration, effectively enhancing the selectivity of nanochannel detection. Summary of the Invention

[0005] This invention aims to provide an application of a highly selective molecularly imprinted nanocomposite membrane in the detection of the pesticide dimethoate. By ingeniously introducing molecular imprinting technology into nanochannels, this invention first synthesizes a molecularly imprinted polymer with a dimethoate-imprinted cavity, and then uses superassembly technology to uniformly load it onto an AAO substrate to obtain a molecularly imprinted nanocomposite membrane capable of specifically recognizing dimethoate molecules. This invention utilizes a sensing system based on a molecularly imprinted nanochannel membrane to achieve specific recognition of dimethoate, effectively improving the selectivity of nanochannel detection.

[0006] The technical solution of the present invention is described in detail below.

[0007] This invention provides an application of molecularly imprinted nanochannel membranes in the selective detection of dimethoate, by using molecularly imprinted nanochannel membranes...

[0008] Channel membranes, used as ion-selective membranes, are used to construct nanofluidic devices for the detection of dimethoate molecules; the molecularly imprinted nanochannel membranes are prepared by the following method:

[0009] (1) Disperse monodisperse silica nanospheres in a solvent to obtain a silica dispersion;

[0010] (2) Add the functional monomer acrylamide and the template molecule dimethoate to the silica dispersion in step (1) and let it stand at room temperature for 1-3 hours to perform pre-assembly.

[0011] (3) Add crosslinking agent and initiator to the pre-assembled system, and carry out polymerization reaction at a temperature of 50-70℃. After the polymerization reaction is completed, separate the solid and liquid, and wash the solid polymerization product with ethanol.

[0012] (4) The solid polymer product is dispersed in a mixed solvent of methanol and acetic acid. The template molecules are extracted from the solid polymer product using the mixed solvent of methanol and acetic acid at a temperature of 50-70℃. After the extraction is completed, solid-liquid separation, washing with ethanol and drying are performed in sequence to obtain molecularly imprinted polymer nanoparticles.

[0013] (5) Molecularly imprinted polymer nanoparticles are dispersed in an alcohol-water mixed solvent, and molecularly imprinted nanochannel membranes are prepared by vacuum filtration onto porous alumina AAO.

[0014] In this invention, in step (2), the mass ratio of silica, functional monomer and template molecule is (7.5-12.5):1:(2-2.5); in step (3), the crosslinking agent is ethylene glycol dimethacrylate, the initiator is azobisisobutyronitrile, and the amount of crosslinking agent added is 0.4%~0.6% of the molar number of functional monomer; in step (5), the volume ratio of ethanol and water in the alcohol-water mixed solvent is 1:1; the feeding ratio of molecularly imprinted polymer nanoparticles and alcohol-water mixed solvent is 2:5-1:2 g / L.

[0015] In this invention, the application method is as follows: Two half-conductivity cells are used, and the molecularly imprinted nanocomposite membrane is placed between the two half-conductivity cells. Electrolyte solutions of the same concentration are added to the two half-conductivity cells. A pair of Ag / AgCl electrodes are placed in the two half-conductivity cells and connected to an external load to form a circuit. The IV change of the molecularly imprinted nanocomposite membrane is recorded with a picoammeter when different concentrations of dimethoate electrolyte solutions are added. A standard curve is fitted with dimethoate concentration and current intensity as variables, and then used to detect the concentration of dimethoate in actual samples.

[0016] In this invention, the electrolyte solution is 10 -4 A potassium chloride solution of mol / L.

[0017] In this invention, the concentration of the dimethoate solution is 0-180 μmol / L.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention utilizes the abundant channel structure and molecularly imprinted cavity distribution in molecularly imprinted nanocomposite membranes, and leverages the high selectivity of molecularly imprinted nanocomposite membranes and the interaction between monomers and dimethoate in imprinted polymers to detect dimethoate molecules in solution, exhibiting high selectivity and sensitivity.

[0020] This invention utilizes an interfacial superassembly strategy to filter molecularly imprinted polymers onto an AAO substrate, resulting in a membrane with abundant surface groups, a symmetrical channel structure, and a uniform charge distribution, thus endowing the membrane with superior ion transport performance.

[0021] The molecularly imprinted nanocomposite membrane utilized in this invention has high mechanical stability and abundant nanochannel structure, which greatly reduces the internal resistance of ion transport and is beneficial for the application of composite membrane in high-sensitivity ion transport.

[0022] The molecularly imprinted nanocomposite membrane used in this invention can achieve highly sensitive detection of dimethoate molecules;

[0023] This invention provides an efficient analytical method for functional superassembled nanochannel thin films, offers a new approach to nanochannel membrane synthesis, and expands its application in the field of highly selective sensing and detection. Attached Figure Description

[0024] Figure 1 These are scanning electron microscope (SEM) images of the prepared molecularly imprinted polymer (a) and nanocomposite film cross-section (b).

[0025] Figure 2 These are Fourier transform infrared spectra of the molecularly imprinted polymer dimethoate before and after elution.

[0026] Figure 3 This is an ultraviolet absorption spectrum of the dimethoate-imprinted polymer prepared in this invention before and after eluting dimethoate.

[0027] Figure 4 This is a diagram illustrating the recognition mechanism of the molecularly imprinted nanocomposite film prepared in this invention.

[0028] Figure 5 The graph shows the stability (a) and reaction time (b) of the molecularly imprinted nanocomposite film prepared by this invention.

[0029] Figure 6 This invention relates to the application of molecularly imprinted nanocomposite membranes (a) and non-imprinted nanocomposite membranes (b) in the detection of the pesticide dimethoate. Detailed Implementation

[0030] To illustrate the present invention in more detail, it will be described in detail below with reference to examples and accompanying drawings:

[0031] Example 1: Application of molecularly imprinted nanochannel sensing system in selective recognition of dimethoate molecules

[0032] The first step is the preparation of molecularly imprinted nanocomposite films based on an interfacial superassembly strategy:

[0033] Step 1: Mix 32.4 mL of ethanol, 49.5 mL of water and 18 mL of ammonia in a 500 mL flask and stir magnetically at 1100 rpm until homogeneous;

[0034] Step 2: Add 91 mL of ethanol and 9 mL of tetraethyl silicate to the above reaction solution and stir at 400 rpm at room temperature for 2.0 h;

[0035] Step 3: After the reaction is complete, centrifuge the product, wash it alternately with water and ethanol, and finally collect the product and dry it overnight in a vacuum drying oven at 60 °C.

[0036] Step 4: Take an appropriate amount of the dried product (100 mg) and add it to 60 mL of acetonitrile. After ultrasonic dispersion, add 10.2 mg of the functional monomer acrylamide and 22.9 mg of the target analyte (dimethoate) and let stand for 2 hours.

[0037] Step 5: After the above reaction system is pre-assembled, add 134.4 μL of crosslinking agent ethylene glycol dimethacrylate to the system, purge with nitrogen for 15-20 min to remove air from the system, then add the reaction initiator azobisisobutyronitrile, and place the reaction system in a 65℃ oil bath for 24 h.

[0038] Step 6: After the above polymerization reaction is completed, centrifuge to collect the polymerization product and wash it three times with ethanol;

[0039] Step 7: After washing the product, disperse all the product in methanol / acetic acid (v / v=48:2), and after ultrasonic dispersion, place the system in a 60℃ oil bath for extraction overnight (the synthesis method of non-imprinted nanochannels is the same as that of molecularly imprinted nanochannels, except that no target analyte is added).

[0040] Step 8: Centrifuge to collect the above product, wash it three times with ethanol, and dry it overnight in a vacuum drying oven at 60 °C to obtain molecularly imprinted polymer nanoparticles. The molecularly imprinted nanochannels eluted have imprinted pores that match the shape, size and functional groups of dimethoate molecules. In subsequent tests, dimethoate molecules can be selectively adsorbed to induce changes in current.

[0041] Step 9: Take an appropriate amount of molecularly imprinted polymer nanoparticles and disperse them evenly with water / ethanol (v / v=1:1);

[0042] Step 10: Take an appropriate amount of the above solution and load molecularly imprinted nanoparticles onto AAO by vacuum filtration to form a molecularly imprinted nanocomposite film.

[0043] The second step is to combine the prepared molecularly imprinted nanochannel membrane with a conductivity cell to form a nanofluidic device: the composite membrane is placed vertically between two half conductivity cells;

[0044] The third step involved adding potassium chloride solutions containing and without dimethoate to two semi-conductivity cells. Pitot ammeters were used to record the IV changes of the molecularly imprinted nanocomposite membranes when electrolyte solutions of different concentrations of dimethoate (0-180 μM) were added. By recording the current in the molecularly imprinted nanocomposite membranes obtained by adding dimethoate solutions of different concentrations, a standard curve was fitted using dimethoate concentration and current intensity as variables to obtain the linear relationship between dimethoate concentration and current, thus evaluating the response of the molecularly imprinted nanocomposite membrane to dimethoate molecules.

[0045] The fourth step involved replacing the dimethoate molecules with competing molecules of corresponding concentrations. These competing molecules included pesticides such as cypermethrin, deltamethrin, fenvalerate, bifenthrin, permethrin, diphenylamine, acephate, chlorpyrifos, and phoxim. The IV changes of the molecularly imprinted nanocomposite membrane were recorded using the same method when electrolyte solutions of the corresponding competing targets were added. Linear equations were fitted using both the competing targets and the current as variables. By comparing the slopes of the linear equations, the degree of response of the nanocomposite membrane to each target was determined (a larger slope indicates a more pronounced response and better selectivity). The results showed that when competing molecules passed through the nanocomposite membrane, the current did not change significantly, thus demonstrating the membrane's selective recognition capability.

[0046] Figure 1 a and Figure 1 b are scanning electron microscope images of the molecularly imprinted polymer and the molecularly imprinted nanocomposite film, respectively. Figure 1 The nanoparticles in a are uniform in size. Figure 1 In b, the molecularly imprinted nanocomposite film particles are arranged more closely, with a thickness of about 1.3 micrometers. Figure 2Fourier transform infrared spectra of the molecularly imprinted polymer of the pesticide dimethoate before and after elution. The infrared spectra show that the characteristic peaks of the template molecule dimethoate disappeared after the molecularly imprinted polymer eluted the template molecule, indicating that dimethoate was successfully eluted from the molecularly imprinted polymer. Figure 3 This is the UV absorption spectrum of the dimethoate-imprinted polymer prepared in this invention before and after dimethoate removal. As can be seen from the UV absorption spectrum, the characteristic absorption peak of dimethoate at 230 nm disappears significantly after dimethoate removal. This indicates that the present invention has successfully synthesized a molecularly imprinted polymer with specific pores of dimethoate molecules and successfully fabricated it into a molecularly imprinted nanocomposite membrane, which can be used for subsequent nanochannel experiments.

[0047] Figure 4 This is a diagram illustrating the recognition mechanism of the molecularly imprinted nanocomposite membrane prepared in this invention. As can be seen from the diagram, when dimethoate molecules pass through the molecularly imprinted nanocomposite membrane, the dimethoate molecules are specifically recognized and adsorbed in the nanochannel, thereby causing a change in current. However, when dimethoate molecules pass through the non-imprinted nanochannel, since there is no corresponding molecularly imprinted cavity in the channel, they will pass through the nanochannel together with other competing targets and will not cause a significant change in current. Figure 5 The molecularly imprinted nanocomposite film prepared by this invention was placed in different concentrations (10) within 100 min. -3 10 -4 and 10 -5 The stability of the molecularly imprinted nanocomposite membrane in potassium chloride solution (a) and the change of current over time after the addition of 50 μM dimethoate-potassium chloride solution (b) show that the molecularly imprinted nanocomposite membrane has excellent stability, which is beneficial for subsequent experimental testing. The reaction rate of the molecularly imprinted nanocomposite membrane after the addition of 50 μM dimethoate-potassium chloride solution is also very fast, and the current tends to stabilize at around 2.0 min. Figure 6 This invention demonstrates the application of the molecularly imprinted nanocomposite membrane (a) and the non-imprinted nanocomposite membrane (b) in the detection of the pesticide dimethoate. A comparison of the two figures shows that the molecularly imprinted nanocomposite membrane exhibits a more pronounced current change trend in its response to dimethoate compared to the non-imprinted nanocomposite membrane. By fitting the data, the relationship between the current (I) of the molecularly imprinted nanocomposite membrane and the dimethoate concentration (I / B) was obtained. C DMT The linear relationship is I0 / I = 0.014 C DMT +1.13 (where I0 is the initial current of the molecularly imprinted nanochannel without the addition of dimethoate), according to the method for calculating the detection limit (LOD=3σ / k (n=10), where... σ This represents the relative standard deviation after 10 tests of the blank solution. kThe slope of the obtained linear equation is given by n, where n is the number of tests. The detection limit of the molecularly imprinted nanocomposite membrane dimethoate solution is 0.01402 nM, which is consistent with... Figure 4 Mechanism description.

[0048] This invention provides a novel material for nanofluidic membrane devices in the sensing and detection of molecular targets by preparing a molecularly imprinted nanocomposite membrane with abundant surface groups, molecularly imprinted cavities, and uniform charge distribution through an interfacial superassembly strategy.

[0049] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. Use of a molecularly imprinted nanochannel membrane for selective detection of dimethoate, characterized in that, The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane.

2. Use according to claim 1, characterized in that, The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane.

3. Use according to claim 1, characterized in that, The electrolyte solution is 10 -4 mol / L potassium chloride solution.

4. Use according to claim 1, characterized in that, The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. 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The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. 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The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. The application discloses a method for detecting dimethoate by using a nanofluid device constructed by a molecular imprinting nanochannel membrane as an ion selective membrane. 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