CN110790933A - Patulin magnetic molecularly imprinted polymer and preparation method and application thereof - Google Patents
Patulin magnetic molecularly imprinted polymer and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of a patulin magnetic molecularly imprinted polymer, which comprises the steps of firstly preparing large-particle-size ferroferric oxide nanoparticles by a hydrothermal method, and then preparing Fe3O4@SiO2Microspheres of Fe3O4@SiO2Polymerizing the microspheres after vinylation to prepare the patulin magnetic molecularly imprinted polymer. The magnetic molecularly imprinted polymer of patulin prepared by the method has the advantages of remarkably improved adsorption rate, capability of achieving adsorption balance in 60 minutes, capability of keeping stable and reusable performance after repeated regeneration, strong specificity,the preparation time is short. The magnetic molecularly imprinted polymer for patulin prepared by the method is more favorable for the pretreatment of a sample for the rapid detection of patulin.
Description
Technical Field
The invention belongs to a detection technology, and particularly relates to a patulin magnetic molecularly imprinted polymer, and a preparation method and application thereof.
Background
Patulin (PAT) is a fungal secondary metabolite with strong toxicity to the nervous system, tissues and cells of the animal body, has potential carcinogenicity, teratogenicity and mutagenicity, and is classified as a class 3 carcinogen by the international agency for research on cancer (IARC). PAT is widely existed in fruits, vegetables and products such as apple, hawthorn, plum, banana, pineapple, pepper, grape, carrot and the like, and the main pollution objects are apple, apple juice and related products. In order to control the hazards of PAT, strict limiting standards have been established by many countries and agencies. Patent CN110156941A preparation of Fe by copolymerization3O4As a material, 4-vinylpyridine is used as a polymer, and trimethylolpropane trimethacrylate or ethylene glycol dimethacrylate is used as a cross-linking agent to prepare a molecularly imprinted polymer. The particle size of the nano particles prepared by the method is about 50-80nm, the polymerization time is 48h, the imprinting material has small particle size, the surface imprinting effect is poor, the required binding time of the adsorbent is long, the specific binding capacity is poor, the polymerization time is long, and manpower and material resources are consumed. The research on the preparation and application of the splay penicillin molecularly imprinted polymer in the academic thesis adopts activated silicon spheres as a carrier, 3-aminopropyl triethoxysilane as a polymer and tetraethoxy silane as a cross-linking agent, and the polymerization time is 12 hours. The activated silicon spheres are used as imprinting materials, so that a polymer cannot be effectively and quickly separated from an actual sample in a complex sample, and the activated silicon spheres have certain adsorption capacity, so that a non-specific adsorption process cannot be effectively used for extracting a target substance in the adsorption process. A patulin molecular imprinting solid-phase extraction technology CN 110068625A adopts a copolymerization method to polymerize 4-vinylpyridine as a polymer trimethylolpropane trimethacrylate as a cross-linking agent for 48 hours to prepare a molecular imprinting polymer, and combines LC-MS to detect the patulin. A large number of binding sites of the imprinted polymer prepared by the copolymerization method do not have the problems that the imprinted polymer with poor adsorption capacity on the surface of the polymer is difficult to separate from an actual sample and the like, and the detection cost is high by combining LC-MS. Surface imprinting method for preparing magnetic patulin for the researchThe molecularly imprinted polymer is used for inspecting the adsorption performance and the selectivity of the polymer on the patulin, and the technology is used for specifically adsorbing the patulin in the apple juice to prepare the specific adsorption material with high recovery rate and high precision.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the prior art, the application provides a patulin magnetic molecularly imprinted polymer and a preparation method and application thereof.
The technical scheme is as follows: the preparation method of the patulin magnetic molecularly imprinted polymer comprises the following steps:
(1) hydrothermal method for preparing Fe3O4Nano-particles:
weighing FeCl3·6H2Dissolving O and trisodium citrate in ethylene glycol, adding sodium acetate into the solution system, stirring uniformly, placing the solution system in a hydrothermal reaction kettle for reacting at 180-220 ℃ for 6-14h, cooling to room temperature, washing with ethanol and water, and drying to obtain magnetic Fe3O4Nanoparticles;
(2)Fe3O4@SiO2preparation of microspheres
Weighing the magnetic Fe prepared in the step (1)3O4Placing the nano particles in 0.1mol/L hydrochloric acid solution, performing ultrasonic treatment, uniformly dispersing in ethanol and deionized water, adding 28% concentrated ammonia water and tetraethyl orthosilicate, mechanically stirring at normal temperature for reaction, externally adding a magnetic field for separation after the reaction is finished, washing with deionized water and methanol, and drying to obtain Fe3O4@SiO2Microspheres;
(3)Fe3O4@SiO2vinylation of microspheres
Fe prepared in the step (2)3O4@SiO2Dispersing microspheres in 10% acetic acid methanol solution containing 3- (methacryloyloxy) propyl trimethoxy silane, mechanically stirring at 40-60 deg.C for 16-32h, magnetically separating, washing with deionized water and methanol, and drying to obtain Fe3O4@SiO2@C＝C；
(4)Fe3O4@SiO2Preparation of @ C ═ C Molecularly Imprinted Polymers (MIPs)
Dissolving the simulated template molecules diindolone and 3-aminopropyltriethoxysilane in methanol, standing at room temperature, and weighing 200mg of Fe in the step (3)3O4Ultrasonically dispersing the nano material into a mixed solution containing methanol and distilled water, sequentially adding TEOS and concentrated ammonia water, mechanically stirring for 5-10min, adding the solution, mixing, mechanically stirring at room temperature for reaction, separating with a magnet after the reaction is finished, washing with deionized water and methanol, and performing Soxhlet extraction with methanol/acetic acid (9: 1) for 24 hours to elute template molecules.
Wherein, in the step (1), the FeCl is3·6H2The molar ratio of O to trisodium citrate is in the range of 1: 1-3, preferably the mixture ratio is 1: 2. the hydrothermal reaction time in the step (1) is preferably 9-11 h.
In the step (2), the volume of the concentrated ammonia water accounts for 1-5% of the whole reaction volume, and the optimal proportion accounts for 2%.
In the step (2), the tetraethyl orthosilicate and Fe3O4The mass ratio of the nano particles is 1: 3-10, preferably 1: 4-6.
In the step (2), the reaction stirring reaction speed is 150-250 rpm, and the optimal speed is 200 rpm.
In the step (3), the 3- (methacryloyloxy) propyltrimethoxysilane and Fe3O4@SiO21: 3-10, and the optimal proportion is 1: 5-6. The stirring reaction speed is 150rpm-250rpm, the optimal speed is 200rpm, and the reaction time is preferably 20-24 h.
In the step (4), the molar ratio of the 3-aminopropyltriethoxysilane to the diindolone is in the range of 1: 1-5, the optimal proportion is 1: 2-3.
In the step (4), the molar ratio of TEOS to 3-aminopropyltriethoxysilane is 1: 1-3, and the optimal molar ratio is 1: 2. the volume of the concentrated ammonia water is 2-3% of the reaction system.
In the step (4), the stirring reaction is performed at a stirring speed of 150-.
The magnetic molecularly imprinted polymer of patulin prepared by the method is also in the protection scope of the invention.
The application of the magnetic molecularly imprinted polymer for detecting the patulin is also within the protection scope of the invention.
Ultra-smooth Fe prepared by hydrothermal method adopted by research3O4The particle size is about 300nm, the adopted polymer is APTES cross-linking agent TEOS, and the polymerization time is 1 h. Greatly shortens the reaction time, and the prepared large-particle-size super-cis Fe3O4The nanoparticles have stronger magnetism and are beneficial to separation from a complex system, and the adsorption to the patulin can be realized within 30min, and the specific recognition effect to the patulin is stronger.
Has the advantages that: compared with the prior art, the method has the following advantages:
(1) the prepared ferroferric oxide nano particles have larger particle size (about 300 nm), can remarkably improve the adsorption rate, can reach adsorption balance only in 60 minutes, and is more favorable for the pretreatment of a sample for the rapid detection of patulin.
(2) The imprinted polymer finally prepared from the large-particle-size material is more stable, has good recycling capability, and can still keep stable and reusable performance after being regenerated for many times.
(3) The method has the advantages that the specific recognition capability is realized on the required recognition substances, the adsorption capability difference experiment of the molecularly imprinted polymer and the non-molecularly imprinted polymer is performed through adsorption kinetics and adsorption thermodynamic experiments, the adsorption capability is remarkably improved, the selective experiment of the patulin and the structural analogue 5-hydroxyfurfural with the largest interference in the recognition is also performed, and the selectivity is greatly enhanced.
(4) The synthesis time of the final polymerization functional monomer is greatly shortened by adopting APTES (3-aminopropyltriethoxysilane), and only 1h is needed.
Drawings
FIG. 1 is Fe prepared in example 13O4Nanoparticle and molecularly imprinted polymer Fe3O4Scanning Electron microscopy of @ MIP;
FIG. 2 is Fe prepared in example 13O4Nanoparticle and molecularly imprinted polymer Fe3O4Transmission electron micrographs of @ MIP;
FIG. 3 shows the results of magnetic measurements of the products of steps (1) to (4) of example 1;
FIG. 4 shows the results of infrared measurements of the products of steps (1) to (4) of example 1;
FIG. 5 shows the results of the kinetics of adsorption of the product of example 1 on patulin in apple juice;
FIG. 6 shows the thermodynamic experimental results of the adsorption of the product of example 1 on patulin in apple juice;
FIG. 7 is the product reuse efficiency of example 1;
FIG. 8 is Fe prepared in comparative example 13O4Nanoparticle and molecularly imprinted polymer Fe3O4Transmission electron micrographs of @ MIP;
FIG. 9 shows the results of the kinetics of adsorption of patulin in apple juice with the product of comparative example 1;
FIG. 10 shows the thermodynamic experimental results of the adsorption of patulin in apple juice by the product of comparative example 1;
figure 11 is the comparative example 1 product recycle.
Detailed Description
The present application will be described in detail with reference to specific examples.
Example 1
A preparation method of a patulin magnetic molecularly imprinted polymer comprises the following steps:
(1) hydrothermal method for preparing Fe3O4Nanoparticles
FeCl3·6H2O (1.38g) + trisodium citrate (0.5g) was dissolved in 40mL of ethylene glycol. To the above solution system was added 1.2g of sodium acetate, and the solution was stirred until homogeneous (about 0.5 h). The mixture is transferred into a 50mL hydrothermal reaction kettle to react for 10h at 200 ℃. And cooling to room temperature. Washed repeatedly three times with ethanol and water (vacuum dried at 55 ℃ C.).
(2)Fe3O4@SiO2Preparation of microspheres
Accurately weighing 0.2g of the magnetic Fe prepared in the step (1)3O4Nanoparticles are placed in 1And (2) performing ultrasonic treatment for 10min in 00mL of 0.1mol/L hydrochloric acid solution, then uniformly dispersing in 80mL of ethanol and 20mL of deionized water, adding 2mL of 28% concentrated ammonia water and 1mL of tetraethyl orthosilicate, stirring at 200rpm and reacting for 6h, after the reaction is finished, externally adding a magnetic field for separation, repeatedly washing the deionized water and methanol, and drying in a vacuum drying oven at 55 ℃.
(3)Fe3O4@SiO2Vinylation of microspheres
200mg of prepared Fe3O4@SiO2The microspheres were dispersed in 100mL of 10% acetic acid methanol solution containing 0.6mL3- (methacryloyloxy) propyltrimethoxysilane, magnetically separated at 50 ℃ with mechanical stirring for 24h, washed three times with deionized water and methanol, and vacuum dried at 55 ℃.
(4)Fe3O4@SiO2Preparation of @ C ═ C Molecularly Imprinted Polymers (MIPs)
Dissolving 0.5mmol of simulated template molecule diindolone and 2mL of 3-Aminopropyltriethoxysilane (APTES) in 10mL of methanol, standing at room temperature for 3h, and accurately weighing 200mg of the Fe3O4Ultrasonically dispersing the nano material into a mixed solution containing 30mL of methanol and 5mL of distilled water, sequentially adding 2mL of TEOS and 1mL of concentrated ammonia water, mechanically stirring for 5min, adding the solution, mixing, mechanically stirring for 1h at room temperature, separating by using a magnet after the reaction is finished, washing by deionized water and methanol for a plurality of times, and performing Soxhlet extraction by using methanol/acetic acid (9: 1) for 24 hours to elute template molecules.
The preparation of non-molecularly imprinted polymers (NIP) is the same as the preparation of magnetic Molecularly Imprinted Polymers (MIP) except that no template molecule is added.
Fe prepared in the step (1)3O4Nanoparticles and the molecularly imprinted polymer Fe prepared in step (4)3O4The Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) of the @ MIP are respectively shown in FIG. 1 and FIG. 2, and according to the illustration, the particle size of the ferroferric oxide nano particles synthesized by the hydrothermal method is about 300nm, the appearance and the particle size are relatively uniform, the particle size of the molecularly imprinted polymer and the particle size are about 450nm, the size of the molecularly imprinted layer is about 75nm, and the successful occurrence of the surface imprinting reaction is shown. Transmission electron microscope and scanningThe results of the scanning electron microscope are the same.
The results of the magnetic assay (VSM) of the products of the above steps (1) to (4) are shown in FIG. 3, in which a. Fe3O4b.Fe3O4@SiO2c.Fe3O4@SiO2-C＝C d.Fe3O4@SiO2-C ═ C @ MIP, as can be seen from the figure, pure Fe3O4The coercive force and remanence of the particles are close to zero, the particles show superparamagnetism, and the saturation magnetization is 47.09emu/g, Fe3O4@SiO2With Fe3O4@SiO2The saturation magnetizations of @ C ═ C are 31.40emu/g and 24.61emu/g, respectively, and the saturation magnetizations of MIP approach to 6.82emu/g and 6.87emu/g, indicating that with the increase of surface modifications, the magnetism is weakened, but the final imprinted material still has good superparamagnetic properties. By means of an external magnetic field, a fast solid-liquid phase separation can be achieved.
The infrared detection results of the products obtained in the steps (1) to (4) are shown in FIG. 4, and Fourier transform infrared (FT-IR) spectra are used for detecting the modification of the magnetic nanoparticles, wherein a. Fe3O4b.Fe3O4@SiO2c.Fe3O4@SiO2-C＝C d.Fe3O4@SiO2-C ═ C @ MIP, as can be seen from the figure, Fe3O4Bands at 1608 and 1394cm-1 are associated with the carboxylate groups of the citric acid groups on stretching, about 580 and 460cm-1Is the typical stretching vibration peak of Fe-O. These bands were found to confirm Fe3O4The surface is connected with carboxyl. 1000cm-1The peak is the Si-O-Si stretching vibration peak, 160cm-1The absorption peak at (b) is the C ═ C bond absorption oscillation peak of MPS. This also confirms that the carbon-carbon double bond is linked to Fe3O4On the surface of the nanoparticles. 1560cm-1Is 2931cm of the characteristic absorption peak of N-H of APTES-1Is the stretching vibration peak of the C-H bond, thereby indicating that the MIP layer is successfully wrapped in Fe through the copolymerization reaction of APTES3O4And (4) the surface of the nanosphere.
Example 1 application of Molecularly Imprinted Polymer (MIP) prepared in preparation to actual sample
Dynamic adsorption experiment
The experimental method comprises the following steps: in order to examine the adsorption rate of the polymer prepared by the experiment on the target substance patulin added in the actual sample apple juice, 7 groups of 20mg MIPs and NIPs are accurately weighed respectively, placed in a 10mL centrifuge tube, 2mL of 20mg/L patulin solution is added respectively, fixed on an air shaking table, centrifuged for 15min at 5000r/min by a centrifuge at room temperature and different vibration time (10min, 20min, 30min, 60min, 90min, 180min, 360min, 720min and 1440min), the supernatant is taken to pass through a 0.22 mu m filter membrane, the concentration of the patulin in the supernatant is measured on a high performance liquid chromatograph, and the adsorption capacity of the polymer is calculated according to a formula.
Wherein Ci represents the initial concentration of template molecules in solution (mg. L)-1) And Cf represents the concentration of the solution (mg. L) after adsorption and dilution-1) K represents the dilution factor, W represents the amount of polymer added (g), and V represents the volume of solution added (mL).
As shown in FIG. 5, the graph shows that the MIP has a rapid increase in the adsorption amount before 30min and a slow rate, and the MIP reaches the adsorption equilibrium substantially at 60min, the adsorption amount is 1.94mg/g, and the MIP reaches the maximum adsorption amount of 1.97mg/g at 90 min. The adsorption behavior of the NIP is basically consistent with that of the MIP, but the adsorption quantity is obviously reduced, and the NIP is 5.5 times of that of the MIP at 90 min.
Thermodynamic adsorption experiment
The concentration of the adsorption solution affects the adsorption amount of the polymer, and too high or too low concentration is not favorable for adsorption. In order to study the relationship of the adsorption amount with the change of the concentration of the adsorption solution, an adsorption isotherm is drawn. Eight groups of MIPs and NIPs are accurately weighed according to the amount of 20mg of each part, are respectively placed in 10mL centrifuge tubes, 2mL of apple juice with different concentrations are respectively added with patulin solutions (2mg/L, 5mg/L, 10mg/L, 15mg/L, 20mg/L, 30mg/L, 40mg/L and 50mg/L), and the mixture is placed in an air shaking bed and shaken at room temperature for 90 min. Then centrifugating at 5000r/min for 15min, collecting supernatant, filtering with 0.22 μm filter membrane, and measuring with high performance liquid chromatograph. And calculating the adsorption capacity of the polymer according to a formula.
Wherein Ci represents the initial concentration of template molecules in solution (mg. L)-1) And Cf represents the concentration of the solution (mg. L) after adsorption and dilution-1) K represents the dilution factor, W represents the amount of polymer added (g), and V represents the volume of solution added (mL).
As shown in FIG. 6, it can be seen that the adsorption amounts of MIPs and NIPs increase with the increase of concentration, and the equilibrium of 3.99mg/g is reached when the concentration reaches 40mg/L, but the increase of NIPs is lower than that of MIPs, and the adsorption amount at the same concentration is much smaller than that of MIPs. This indicates that the template molecule leaves imprinted pores in the imprinted polymer during imprinting, making its affinity for the template molecule much higher than that of the non-imprinted polymer.
Repeated utilization experiment
To evaluate the recycling rate of the magnetic molecularly imprinted polymer, 20mg of the imprinted polymer was weighed into 2mL of a 20 μ g/mL patulin apple juice solution, stirred and shaken at room temperature for 90min, separated with a magnet, and purified with methanol: soxhlet extraction with acetic acid (9: 1/v: v) for 24h to desorb the adsorbed patulin, vacuum drying the eluted material at 55 ℃ to constant weight, repeating the same adsorption and desorption process for 8 times, and observing the change of the adsorption effect of the imprinted polymer.
As shown in FIG. 7, it is clear that the adsorption amount of the polymer material is slightly decreased after a plurality of uses, but the adsorption amount can be maintained at about 2 mg/g. This indicates that the recognition site of the MIP remains stable and reusable after multiple regenerations. The patulin is eluted from the polymer by washing with a mixed solution of methanol and acetic acid. Therefore, the synthesized molecularly imprinted polymer has strong adsorption capacity and high stability, can realize the recycling of materials by a simple method, and greatly reduces the process of sample pretreatment compared with the traditional materials.
Selectivity test
Respectively weighing 20mg of the molecularly imprinted polymer, the non-imprinted polymer and the activated silica spheres (Alatin), placing the weighed materials into a 10mL centrifuge tube, respectively adding 2mL of mixed standard solution of patulin and 20 mg/mL of HMF, placing the materials into an air shaking table, shaking the materials at room temperature, centrifuging the materials for 16min by a centrifuge at 5000r/min, taking supernate, filtering the supernate with a 0.22 mu m filter membrane, and respectively calculating the adsorption capacity of the polymer in a high performance liquid chromatograph and an ultraviolet spectrophotometer according to a formula.
This specific selection of MIP polymers can be represented by a partition coefficient Kd and a selectivity coefficient K.
Wherein Ci represents the concentration of the analyte in the solution before adsorption, Cf represents the concentration of the analyte in the solution after adsorption, M represents the amount of the polymer, and V represents the volume of the standard solution added.
As can be seen from the table, the adsorption capacity of the polymer to patulin is 1.953mg/g, which is obviously higher than the adsorption capacity of NIP (nitrate-functionalized protein) of 0.352mg/g and the adsorption capacity of activated silica spheres of 0.172mg/g, and the result shows that the imprinted polymer has good adsorption performance to the target object. The adsorption capacity of MIP to HMF is 0.492mg/g and is almost one fourth of the adsorption capacity of patulin, which shows that the selectivity of MIP to patulin is far higher than that of the structural analogue.
As can be seen from the table, the partition coefficient value of MIP for patulin is 4155.32, but it is much lower for 5-hydroxyfurfural (32.62), which is 127 times higher than the latter. This shows that the imprinted polymer synthesized according to a certain predetermined structure forms a specific binding site for patulin, even for substances with very similar structures, the imprinted polymer only shows simple physical adsorption due to the existence of specific cavities, and the imprinted polymer can show specific adsorption for patulin, so that the imprinted polymer can be effectively separated and identified. The partition coefficient values of the non-imprinted polymer and the activated silicon spheres to the two targets are lower (21.36 and 9.41 respectively, and the partition coefficient value of the imprinted polymer is 194 times, which shows that the synthesized imprinted polymer with specific cavities has better adsorption capacity to the patulin compared with the imprinted polymer which is not arranged and only forms the non-imprinted polymer by disordered combination and the activated silicon spheres which are simple.
The experimental data show that a three-dimensional cavity with a specific binding site for patulin is formed in the imprinted polymer, so that the imprinted polymer has better selectivity and adsorption capacity for patulin compared with a non-imprinted polymer and activated silicon spheres, and can be used as a good enrichment material to effectively separate and extract the patulin.
Comparative example 1
This comparative example was operated as in example 1, except that step (1) was modified to:
preparation of Fe3O4 nano-particles by coprecipitation method
2.000g of citric acid was weighed out accurately and dissolved in 5mL of water for use. Weighing 2.4g FeCl3 & 6H2O and 1g FeCl2 & 4H2O, dissolving in 40mL deionized water, magnetically stirring, heating to 80 ℃ under the protection of nitrogen, adding 5mL concentrated ammonia water, and rapidly stirring. After reacting for 30min, adding the prepared citric acid solution, heating to 95 ℃, reacting for 90min at constant temperature, stopping stirring, washing with deionized water for multiple times to remove redundant ammonia water and impurities, and drying in vacuum.
Similarly, the preparation of non-molecularly imprinted polymers (NIP) was carried out in the same manner as the preparation of magnetic Molecularly Imprinted Polymers (MIP) except that no template molecule was added.
Comparative example 1 Fe3O4Nanoparticle and molecularly imprinted polymer Fe3O4As shown in FIG. 8, the transmission electron microscope (SEM) of @ MIP shows that the particle size of the ferroferric oxide nanoparticles synthesized by the coprecipitation method is about 30nm, the particle size of the molecular imprinting polymer is about 80nm, and the molecular imprinting layer is about 25 nm.
Comparative example 1 results of application of the polymer prepared:
experiment of adsorption Property
The experimental procedure is the same as that of example 1, and the statistical results are shown in fig. 9, and it can be seen from the graph that the MIP of comparative example 1 rapidly increases in adsorption amount before 90min, then slows down in rate, reaches adsorption equilibrium substantially at 120min, and has an adsorption amount of 1.80mg/g and a maximum adsorption amount of 1.83mg/g at 180 min. The adsorption behavior of NIP was consistent with MIP, but the adsorption was significantly reduced. Example 1 equilibrium time of the polymer synthesized by hydrothermal method is 60min, and maximum adsorption capacity is 1.97mg/g at 90 min.
Thermodynamic adsorption experiment
Experimental procedures were performed in the same manner as in example 1, and statistical results are shown in FIG. 10, which shows that, as the concentration increases, the adsorption amounts of MIPs and NIPs in comparative example 1 also increase, and when the concentration reaches 40mg/L, the maximum adsorption amount is 3.01mg/g, but the increase of NIPs is lower than MIPs, and the adsorption amount at the same concentration is much lower than that of MIPs. This indicates that the template molecule leaves imprinted pores in the imprinted polymer during imprinting, making its affinity for the template molecule much higher than that of the non-imprinted polymer. Example 1 the maximum adsorption capacity of the hydrothermally synthesized polymer was 3.99mg/g at a concentration of 40 mg/g.
Repeated utilization rate experiment
Experimental procedure the same procedure as in example 1 was used, and the statistical results are shown in fig. 11, which shows that the polymeric material of comparative example 1 shows a significant decrease in the amount adsorbed after 3 uses, the fifth amount being about 40% of the first amount. Therefore, compared with the molecularly imprinted polymer synthesized by the coprecipitation method in the comparative example 1, the polymer synthesized by the hydrothermal method in the example 1 has strong adsorption capacity and high stability after eight times of use, the material can be recycled by a simple method, and compared with the traditional material, the sample pretreatment process is greatly reduced.
Claims (9)
1. A preparation method of a patulin magnetic molecularly imprinted polymer is characterized by comprising the following steps:
(1) hydrothermal method for preparing Fe3O4Nano-particles:
weighing FeCl3·6H2Dissolving O and trisodium citrate in ethylene glycol, adding sodium acetate into the solution system, stirring uniformly, placing the solution system in a hydrothermal reaction kettle for reacting at 180-220 ℃ for 6-14h, cooling to room temperature, washing with ethanol and water, and drying to obtain magnetic Fe3O4Nanoparticles;
(2)Fe3O4@SiO2preparation of microspheres
Weighing the magnetic Fe prepared in the step (1)3O4Placing the nano particles in 0.1mol/L hydrochloric acid solution, performing ultrasonic treatment, uniformly dispersing in ethanol and deionized water, adding 28% concentrated ammonia water and tetraethyl orthosilicate, mechanically stirring at normal temperature for reaction, externally adding a magnetic field for separation after the reaction is finished, washing with deionized water and methanol, and drying to obtain Fe3O4@SiO2Microspheres;
(3)Fe3O4@SiO2vinylation of microspheres
Fe prepared in the step (2)3O4@SiO2Dispersing the microspheres in 10% acetic acid methanol solution containing 3- (methacryloyloxy) propyl trimethoxy silane, mechanically stirring at 40-60 deg.C for 16-32h, magnetically separating, washing with deionized water and methanol, and drying to obtain Fe3O4@SiO2@C＝C；
(4)Fe3O4@SiO2Preparation of @ C ═ C Molecularly Imprinted Polymers (MIPs)
Dissolving the simulated template molecules diindolone and 3-aminopropyltriethoxysilane in methanol, standing at room temperature, and weighing 200mg of Fe in the step (3)3O4Ultrasonically dispersing the nano material into a mixed solution containing methanol and distilled water, sequentially adding TEOS and concentrated ammonia water, mechanically stirring for 5-10min, adding the above solution, mixing, mechanically stirring at room temperature for reaction, separating with a magnet after the reaction is finished, washing with deionized water and methanol, and performing Soxhlet extraction with methanol/acetic acid (9: 1) for 24 minThe template molecules were eluted in hours.
2. The method for preparing patulin magnetic molecularly imprinted polymer according to claim 1, wherein in the step (1), the FeCl is added3·6H2The molar ratio of O to trisodium citrate is in the range of 1: 1-3.
3. The method for preparing patulin magnetic molecularly imprinted polymer according to claim 1, wherein in the step (2), the volume of the concentrated ammonia water is 1-5% of the whole reaction volume.
4. The method for preparing magnetic molecularly imprinted polymer of patulin according to claim 1, wherein in step (2), the tetraethyl orthosilicate is mixed with Fe3O4The mass ratio of the nano particles is 1: 3-10.
5. The method for preparing patulin magnetic molecularly imprinted polymer according to claim 1, wherein in step (3), the 3- (methacryloyloxy) propyltrimethoxysilane and Fe3O4@SiO21: 3-10.
6. The method for preparing patulin magnetic molecularly imprinted polymer according to claim 1, wherein in the step (4), the molar ratio of 3-aminopropyltriethoxysilane to diindolone is in the range of 1: 1-5.
7. The method for preparing patulin magnetic molecularly imprinted polymer according to claim 1, wherein in the step (4), the molar ratio of TEOS to 3-aminopropyltriethoxysilane is 1: 1-3; the volume of the concentrated ammonia water is 2-3% of the reaction system.
8. The magnetic molecularly imprinted polymer of patulin obtained by the method of any of claims 1 to 7.
9. Use of the magnetic molecularly imprinted polymer of patulin according to claim 8 for detecting patulin.
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