Preparation method and application of a multifunctional molecular imprinting polymer for detecting multiple pyrethroid pesticides

Abstract

The present invention discloses a preparation method and application of a multifunctional molecular imprinting polymer for detecting a variety of pyrethroid pesticides. Upconversion fluorescent UCNPs and magnetic materials (Fe3O4) are introduced into the molecular imprinting technology. The prepared polymer can be used for sensing a variety of pyrethroid pesticides and has magnetic characteristics, which is convenient for separation and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a preparation method and application of a multifunctional molecular imprinting polymer for detecting various pyrethroid pesticides. Background Art

[0002] Pyrethroid pesticides are a class of insecticides with broad spectrum, high efficiency and low toxicity. They have been widely used in pest control in the agricultural field in recent years. With the continuous increase in their use, more and more residual pyrethroid pesticides are exposed to the environment. Studies have shown that pyrethroids are highly toxic to environmental organisms that are beneficial to agriculture, such as bees and silkworms. In addition, the residual period of this pesticide is relatively long, and after entering the body, it has obvious toxic effects on the body's immunity and cardiovascular system. More importantly, in actual pesticide residue detection, samples with multiple unknown residue components are often tested, so the development of pesticide multi-residue detection technology is more suitable for scientific research and market demand.

[0003] Light detection is a commonly used rapid detection method. Upconversion nanoparticles (UCNPs) are composed of an inorganic matrix and rare earth doped ions embedded therein. They can convert longer wavelength radiation into shorter wavelength fluorescence through a two-photon or multi-photon mechanism, and have many advantages such as low toxicity, high fluorescence quantum yield, low background noise, stable chemical properties, light stability, high penetration depth, low damage, clear emission band, and large anti-Stokes shift. Due to these excellent optical properties, UCNPs have great application value in the fields of biological imaging, medical treatment, food testing, etc.

[0004] Molecular imprinting technology is a separation technology with predictability, recognition and practicality. This technology can be used to prepare molecularly imprinted polymers (MIPs) with molecular recognition. Compared with antibodies, MIPs have the advantages of easy synthesis, high stability, long life, and reusability, and have good application prospects in the fields of separation and sensing. With the development of materials science, two or more materials are combined to obtain multifunctional composite materials, which have multiple functions. The research on multifunctional composite materials has become a research hotspot in recent years. Due to its excellent multifunctional properties, it has been favored by many researchers. Fe3O4 has always played an important role in multifunctional composite materials. Because of its special magnetism and good biocompatibility, it has many applications in drug delivery, cell separation, stem cell labeling and magnetic resonance imaging. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method and application of a multifunctional molecular imprinting polymer for detecting a variety of pyrethroid pesticides, and to provide a new material for the fields of detection and sensing.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] 1. The present invention provides a method for preparing a multifunctional molecular imprinted polymer for detecting a variety of pyrethroid pesticides, comprising the following steps:

[0008] 1) firstly add 3-phenoxybenzoic acid (3-PBA), phenyltriethoxysilane (PTES) and aminopropyltriethoxysilane (APTES) into anhydrous ethanol, and mix them thoroughly by ultrasonic oscillation, then add tetraethyl orthosilicate (TEOS), and stir and mix to obtain a premixed solution;

[0009] 2) Then PAA-UCNPs and Fe3O4@SiO2-NH2 are added to the premixed solution, and then an ammonia solution is added, stirred and mixed, reacted at room temperature (25°C), centrifuged to obtain a precipitate, washed, and vacuum freeze-dried to obtain the polymer;

[0010] Among them, the PAA-UCNPs are first made of yttrium chloride, ytterbium chloride and erbium chloride as raw materials to make oil-soluble UCNPs, and then the UCNPs are mixed with polyacrylic acid (PAA) for reaction; the Fe3O4@SiO2-NH2 is first made of Fe3O4 magnetic microspheres and tetraethyl orthosilicate (TEOS) as raw materials, mixed and stirred, and then aminosilane was added dropwise, and the reaction was continued by stirring and magnetic separation.

[0011] Preferably, in step 1), the usage ratio of 3-PBA, PTES, APTES, anhydrous ethanol and TEOS is 50-150 mg: 400-600 μL: 150-350 μL: 8-15 mL: 0.8-1.5 mL, and more preferably 100 mg: 500 μL: 250 μL: 10 mL: 1 mL.

[0012] Preferably, in step 1), the process conditions of ultrasonic oscillation are: ultrasonic frequency 60-80 kHz, duration 3-5 min; the process conditions of stirring are: stirring at 300 r / min for 5-10 minutes.

[0013] Preferably, in step 2), the dosage ratio of UCNPs, Fe3O4@SiO2-NH2, premixed solution and ammonia solution is 200-600 mg: 25-75 mg: 8-12 mL: 1.5-2.5 mL, and more preferably 400 mg: 50 mg: 8-12 mL: 2 mL, wherein the volume concentration of ammonia solution is 6%.

[0014] Preferably, in step 2), the stirring and mixing process conditions are: stirring at 300 r / min for 10 to 20 hours.

[0015] Preferably, in step 2), the reaction time at room temperature is 21 h.

[0016] Preferably, in step 2), 3-PBA is removed by washing with a mixed solution of acetonitrile and glacial acetic acid, wherein the volume ratio of acetonitrile to glacial acetic acid in the mixed solution is 9:1.

[0017] Preferably, in step 2), the specific method of vacuum freeze drying is: precooling at -80°C for 1 hour, and drying at a cold trap temperature of -40 to -60°C for 5 to 10 hours after vacuuming, more preferably 6 hours.

[0018] Preferably, the preparation method of the PAA-UCNPs is as follows:

[0019] A) First, yttrium chloride, ytterbium chloride and erbium chloride are dissolved in oleic acid and octadecene, heated to 150-170°C to form a yellow transparent solution, and then naturally cooled to room temperature; then, a methanol solution of NaOH and NH4F is added dropwise, and stirred at room temperature for 30-60 minutes; then, the methanol is gradually heated to remove the methanol, and the mixture is kept at 80-100°C for 30-60 minutes, and heated to 290-310°C under argon protection, and kept for 50-70 minutes, and naturally cooled to room temperature, and the precipitate is centrifuged and washed with a mixture of ethanol and methanol in a volume ratio of 1:1 to obtain oil-soluble UCNPs;

[0020] B) Then UCNPs are dispersed in toluene with stirring to obtain a toluene solution; polyacrylic acid (PAA) is dissolved in diethylene glycol (DEG), heated to 100-120° C., the toluene solution is continuously added, kept warm at 105-115° C. for 50-70 minutes under argon protection, heated to 230-250° C., kept warm for 50-70 minutes, cooled naturally to room temperature, added with excess hydrochloric acid solution, and centrifuged to obtain PAA-UCNPs.

[0021] Further preferably, in step A), the usage ratio of yttrium chloride, ytterbium chloride, erbium chloride, oleic acid, octadecene, NaOH and NH4F methanol solution and ethanol-methanol mixture is 0.78mmol:0.2mmol:0.02mmol:6mL:17mL:10mL:10-15mL, wherein the methanol solution of NaOH and NH4F is obtained by dissolving 2.5mmol NaOH and 4mmol NH4F in 10mL methanol.

[0022] Further preferably, in step A), the specific method for removing methanol is: first slowly heating to 80° C., keeping warm for 45 minutes to remove most of the methanol, then heating to 100° C., and degassing for 10 minutes to completely remove the methanol.

[0023] Further preferably, in step B), the dosage ratio of PAA, DEG, OA-UCNPs toluene solution and hydrochloric acid solution is 250-350 mg: 25-35 mL: 2-4 mL: 15-20 mL, wherein the concentration of OA-UCNPs contained in the OA-UCNPs toluene solution is 25-50 mg / mL, and the pH of hydrochloric acid is 4.6.

[0024] Preferably, the preparation method of the Fe3O4@SiO2-NH2 is as follows: first, Fe3O4 magnetic microspheres are placed in a mixture of concentrated ammonia water and ethanol aqueous solution, and oscillated for 15 to 20 minutes at an ultrasonic frequency of 60 to 80 kHz to make them evenly dispersed; then, TEOS is added dropwise, and stirred at room temperature for 0.5 to 2 hours, followed by aminosilane addition, and continuous stirring for 8 to 12 hours; the solid product is separated with a magnet, washed with deionized water 3 times, and vacuum dried to obtain the product.

[0025] Further preferably, the dosage ratio of Fe3O4 magnetic microspheres, concentrated ammonia water, ethanol aqueous solution, TEOS, and aminosilane is 0.3g:3mL:450mL:1-5mL:0.1-0.3mL, wherein the volume concentration of concentrated ammonia water is 25-28%, and the volume concentration of ethanol aqueous solution is 85-90%.

[0026] 2. The present invention also provides a multifunctional molecular imprinting polymer obtained by the aforementioned preparation method for detecting multiple pyrethroid pesticides.

[0027] 3. The present invention also provides the use of the aforementioned polymer in the preparation of molecular imprinting sensors for detecting a variety of pyrethroid pesticides.

[0028] Preferably, the pyrethroid pesticides include but are not limited to deltamethrin, cyfluthrin, cypermethrin, and cypermethrin.

[0029] The beneficial effects of the present invention are:

[0030] The present invention introduces upconversion fluorescent UCNPs and magnetic materials (Fe3O4) into molecular imprinting technology. The resulting polymer can be used to sense a variety of pyrethroid pesticides. It also has magnetic characteristics, which facilitates separation and has broad application prospects. The details are as follows:

[0031] 1. The present invention has sensing performance for a variety of pyrethroid pesticides;

[0032] 2. The present invention introduces UCNPs with strong fluorescent properties and magnetic nanomaterials into molecular imprinting technology, so that the composite material has sensing and separation properties and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for explanation.

[0034] Figure 1 is the response curve of the polymer of the present invention to various pyrethroid pesticides, wherein A is deltamethrin, B is cypermethrin, C is cypermethrin, and D is cypermethrin;

[0035] Figure 2 is the specificity of the polymer of the present invention. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] A preparation method of a multifunctional molecular imprinted polymer for multiple pyrethroid pesticides comprises the following steps:

[0039] (1) Preparation of PAA-UCNPs

[0040] A) 0.78mmol YCl3·6H2O, 0.2mmol YbCl3·6H2O and 0.02mmol ErCl3·6H2O were placed in a 100mL three-necked flask, and 6mL OA and 17mL ODE were added. The mixture was mixed evenly on a magnetic stirrer and heated to 160℃ for 1h, at which time a yellow transparent solution was formed. After the reactants were cooled to room temperature, 10.0mL of a methanol solution containing NaOH and NH4F (obtained by dissolving 2.5mmol NaOH and 4mmol NH4F in 10mL methanol) was slowly added dropwise, and stirred continuously at room temperature for 1h to ensure that NH4F was fully reacted. The solution was then slowly heated to 80℃ and maintained for 45min to remove methanol, then heated to 100℃ and degassed for 10min to completely remove methanol. Argon was introduced, and the reactants were quickly heated to 300℃ and maintained for 1h. The obtained solution was naturally cooled to room temperature, centrifuged to obtain the precipitate, and washed four times with a mixture of ethanol and methanol in a volume ratio of 1:1 to obtain oil-soluble UCNPs.

[0041] B) Weigh 300 mg of PAA (MW = 1800) and add it to a 100 mL three-necked flask, add 30 mL of DEG, heat to 110 ° C for 15 min to form a transparent solution. Then slowly add 3 mL of toluene solution containing 100 mg of OA-UCNP and keep it at 110 ° C for 1 h. Then heat to 240 ° C for 1 h. The resulting solution is cooled to room temperature and an excess of dilute hydrochloric acid solution (pH = 4.6) is added. Centrifuge (12000 rpm, 15 min) to obtain PAA-UCNPs, and wash with water 3 times.

[0042] (2) Preparation of Fe3O4@SiO2-NH2

[0043] 0.3 g of Fe3O4 magnetic microspheres (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were placed in a mixture of 450 mL of ethanol and deionized water containing 3 mL of concentrated ammonia (V 乙醇 :V 水 =8:1), ultrasonic for 20 min to make it evenly dispersed. Then 3 mL of TEOS was added dropwise to the above solution, stirred at room temperature for 1 h, and then 0.3 mL of aminosilane was added dropwise, and stirred continuously for 5 h. The solid product Fe3O4@SiO2-NH2 was separated by T2 magnet, washed with deionized water for 3 times, and dried under vacuum at 60 °C for 12 h.

[0044] (3) Preparation of premix

[0045] In a 25 mL flask, add 100 mg of 3-PBA, 10 mL of ethanol, 500 μL of PTES and 250 μL of APTES, and mix thoroughly by ultrasonication. Then, add 1 mL of TEOS and stir for 5 min to obtain a premixed solution.

[0046] (4) Finally, 400 mg PAA-UCNPs and 50 mg Fe3O4@SiO2-NH2 were added to 10 mL of the premixed solution, and then 2 mL of 6% ammonia solution was added. The mixture was stirred at 300 r / min for 20 hours, reacted at room temperature (25°C) for 21 hours, and the precipitate was collected by centrifugation, washed, and vacuum freeze-dried to obtain the polymer.

[0047] Wherein, in step (4), 3-PBA is removed by washing with a mixture of acetonitrile and glacial acetic acid until the template cannot be detected under ultraviolet spectrum, and the volume ratio of acetonitrile to glacial acetic acid in the mixture is 9:1.

[0048] The specific method of vacuum freeze drying is: precooling at -80°C for 1 hour, and drying at a cold trap temperature of -50°C for 6 hours after vacuuming.

[0049] Comparative test

[0050] Non-imprinted polymer (UCNPs / Fe3O4 / NIPs) was prepared according to the method of Example 1, but without adding 3-PBA.

[0051] The sensing performance of the multifunctional molecular imprinting polymer prepared in Example 1 was verified. The specific operation is as follows: 2.0 mg of the multifunctional molecular imprinting polymer or the non-imprinting polymer was added to a 4.0 mL centrifuge tube, and then 200 μL of a solution of deltamethrin, flucythrinate, cypermethrin, and cypermethrin was added, with the final concentrations being 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, and 1.0 mg / L, respectively. The mixture was incubated at room temperature for 60 min, and then the fluorescence value was measured using a fluorescence spectrophotometer with an external 980 nm excitation. Figure 1 (A is cypermethrin, B is flucythrin, C is cypermethrin, and D is cypermethrin) It can be seen that as the concentration of the four pyrethroid pesticides increases, the fluorescence intensity weakens. At the same concentration of pyrethroid pesticides, the fluorescence quenching amount of the multifunctional molecular imprinted polymer is greater than that caused by the non-imprinted polymer.

[0052] Example 2

[0053] Carbaryl, acetamiprid and imidacloprid were selected as competitors to study the specificity of the multifunctional molecular imprinting polymer prepared in Example 1. The concentrations were 5 mg / L pyrethroid pesticides and competitive concentrations. The multifunctional composite material was used to identify the competitive pesticides, and the fluorescence values ​​were measured using a fluorescence spectrophotometer equipped with a 980 nm laser. Figure 2 As shown in the figure, deltamethrin, cyfluthrin, cypermethrin and cypermethrin can strongly quench the fluorescence of the multifunctional molecularly imprinted polymer. However, the competitive pesticides have little effect on their fluorescence. This shows that the method is specific for the four pyrethroid pesticides, namely deltamethrin, cyfluthrin, cypermethrin and cypermethrin.

[0054] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a multifunctional molecularly imprinted polymer for detecting multiple pyrethroid pesticides, characterized in that: The following steps are involved: 1) firstly add 3-phenoxybenzoic acid, phenyltriethoxysilane and aminopropyltriethoxysilane into anhydrous ethanol, and mix them thoroughly by ultrasonic oscillation, then add tetraethyl orthosilicate, and stir to mix well to obtain a premixed solution; 2) Then PAA-UCNPs and Fe3O4@SiO2-NH2 are added to the premixed solution, and then an ammonia solution is added, stirred and mixed, reacted at room temperature, centrifuged to obtain a precipitate, washed, and vacuum freeze-dried to obtain the polymer; The Fe3O4@SiO2-NH2 is prepared by first using Fe3O4 magnetic microspheres and tetraethyl orthosilicate as raw materials, mixing and stirring, then dropping aminosilane, continuing to stir the reaction, and magnetically separating. The preparation method of the PAA-UCNPs is as follows: A) First, yttrium chloride, ytterbium chloride and erbium chloride are dissolved in oleic acid and octadecene, heated to 150-170°C to form a yellow transparent solution, and then naturally cooled to room temperature; then, a methanol solution of NaOH and NH4F is added dropwise, and stirred at room temperature for 30-60 minutes; then, the methanol is gradually heated to remove the methanol, and the mixture is kept at 80-100°C for 30-60 minutes, and heated to 290-310°C under argon protection, and kept for 50-70 minutes, and naturally cooled to room temperature, and the precipitate is centrifuged and washed with a mixture of ethanol and methanol in a volume ratio of 1:1 to obtain oil-soluble UCNPs; B) Then the oil-soluble UCNPs are stirred and dispersed in toluene to obtain an OA-UCNPs toluene solution; then polyacrylic acid is dissolved in diethylene glycol, heated to 100-120° C., the toluene solution is continuously added, and the mixture is kept at 105-115° C. for 50-70 minutes under argon protection, heated to 230-250° C., kept for 50-70 minutes, cooled naturally to room temperature, and an excess of hydrochloric acid solution is added, and the mixture is centrifuged to obtain PAA-UCNPs; In step A), the amount ratio of yttrium chloride, ytterbium chloride, erbium chloride, oleic acid, octadecene, NaOH and NH4F methanol solution and ethanol-methanol mixture is 0.78mmol:0.2mmol:0.02mmol:6mL:17mL:10mL:10-15mL, wherein the methanol solution of NaOH and NH4F is obtained by dissolving 2.5mmol NaOH and 4mmol NH4F in 10mL methanol; In step B), the dosage ratio of polyacrylic acid, diethylene glycol, OA-UCNPs toluene solution and hydrochloric acid solution is 250-350 mg: 25-35 mL: 2-4 mL: 15-20 mL, wherein the concentration of OA-UCNPs contained in the OA-UCNPs toluene solution is 25-50 mg / mL, and the pH of the hydrochloric acid is 4.

6.

2. The preparation method according to claim 1, characterized in that: In step 1), the usage ratio of 3-phenoxybenzoic acid, phenyltriethoxysilane, aminopropyltriethoxysilane, anhydrous ethanol and tetraethyl orthosilicate is 50-150 mg: 400-600 μL: 150-350 μL: 8-15 mL: 0.8-1.5 mL.

3. The preparation method according to claim 1, characterized in that: In step 2), the dosage ratio of PAA-UCNPs, Fe3O4@SiO2-NH2, premixed solution and ammonia solution is 200-600 mg: 25-75 mg: 8-12 mL: 1.5-2.5 mL, wherein the volume concentration of ammonia solution is 6%.

4. The preparation method according to claim 1, characterized in that: In step 2), the stirring and mixing process conditions are: stirring at 300 r / min for 10 to 20 hours; The reaction time at room temperature is 21 h; Using an acetonitrile-glacial acetic acid mixture to wash to remove 3-phenoxybenzoic acid, wherein the volume ratio of acetonitrile to glacial acetic acid in the mixture is 9:1; The specific method of vacuum freeze drying is: precooling at -80°C for 1 hour, and drying at a cold trap temperature of -40 to -60°C for 5 to 10 hours after vacuuming.

5. The preparation method according to claim 1, characterized in that: The preparation method of the Fe3O4@SiO2-NH2 is as follows: firstly, Fe3O4 magnetic microspheres are placed in a mixture of concentrated ammonia water and ethanol aqueous solution, and the mixture is oscillated for 15 to 20 minutes at an ultrasonic frequency of 60 to 80 kHz to make the mixture evenly dispersed; then, tetraethyl orthosilicate is added dropwise, and the mixture is stirred at room temperature for 0.5 to 2 hours, and then, aminosilane is added dropwise, and the mixture is stirred continuously for 8 to 12 hours; the solid product is separated by a magnet, washed with deionized water for 3 times, and dried in a vacuum to obtain the product.

6. A multifunctional molecular imprinting polymer for detecting multiple pyrethroid pesticides obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the polymer according to claim 6 in preparing a molecular imprinting sensor for detecting a variety of pyrethroid pesticides.

8. The use according to claim 7, characterized in that: The pyrethroid pesticides are deltamethrin, cyfluthrin, cypermethrin and cypermethrin.

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