Hydrophilic ceftriaxone magnetic molecularly imprinted polymer, its preparation method and application

Abstract

The application discloses a preparation method of a hydrophilic ceftriaxone magnetic molecular imprinting polymer, which comprises the following steps: taking magnetic iron-aluminum mixed hydroxide as a carrier, ceftriaxone as a template molecule, 3-amino-1,2,4-triazole as a functional monomer, ethylene glycol dimethacrylate as a crosslinking agent, ammonium persulfate as an initiator, and water as a porogen to prepare the hydrophilic ceftriaxone magnetic molecular imprinting polymer. The water-based ceftriaxone magnetic molecular imprinting polymer has high magnetization intensity and a more stable morphological structure, has good adsorption performance on ceftriaxone, reaches adsorption equilibrium within 30s, has an equilibrium adsorption capacity of 6.30mg / g, conforms to a quasi-second-order kinetic adsorption model, and can be directly applied to the determination of cephalosporin antibiotics in a water environment.

Description

Technical Field

[0001] This invention relates to a hydrophilic ceftriaxone magnetic molecularly imprinted polymer, its preparation method, and its application, belonging to the field of magnetic molecularly imprinted polymer preparation technology. Background Technology

[0002] Ceftriaxone (CEF) is a β-lactam antibiotic with a broad antibacterial spectrum and stability against β-lactamases, making it widely used in livestock and aquaculture. However, improper use can lead to drug residues that not only hinder the development of the aquaculture industry but also pose a serious threat to the environment and human health.

[0003] Solid phase extraction (SPE) is the most commonly used pretreatment technique for detecting antibiotic residues in complex samples (biological, food, environmental, etc.). Magnetic dispersive solid phase extraction (MDSPE), utilizing magnetic materials as carriers, offers the advantage of rapid separation and is a widely used drug residue pretreatment technique. Molecularly imprinted polymers (MIPs) show advantages in improving target analyte selectivity and detection sensitivity. Magnetic molecularly imprinted polymers (MMIPs) synthesize molecularly imprinted shells on the surface of magnetic nanoparticles. This not only possesses the advantages of molecular imprinting—specific recognition and adsorption of target molecules—but also simplifies traditional procedures such as column packing, centrifugation, and filtration, achieving solid-liquid separation solely through an external magnetic field. In recent years, researchers have synthesized different types of magnetic nanoparticles for MDSPE, such as Fe3O4 and GO-MWCNTs-Fe3O4. In addition to the materials mentioned above, magnetic mixed metal hydroxides (MMH) are a type of magnetic material that is currently widely used due to their simple and rapid preparation, good stability, and superparamagnetism.

[0004] To avoid the disruption of hydrogen bonds by the polar solvent water during prepolymerization, common magnetic molecularly imprinted polymers (MMIPs) are synthesized in nonpolar organic solvents. They exhibit optimal performance only in non-aqueous environments and are unsuitable for the analysis of hazardous substances in aqueous media, thus limiting their applicability. Furthermore, traditional MMIPs require large amounts of organic or toxic solvents, consuming significant time and energy. Existing preparations of magnetic molecularly imprinted polymers for cephalosporins are all carried out in nonpolar organic solvents, making them unsuitable for the determination of cephalosporins in aqueous environments. Therefore, exploring a green preparation method for hydrophilic magnetic molecularly imprinted polymers that can achieve autonomous assembly and control for specific recognition of ceftriaxone is of great significance. Summary of the Invention

[0005] This invention provides a hydrophilic ceftriaxone magnetic molecularly imprinted polymer, its preparation method, and its application, which can effectively solve the above-mentioned problems.

[0006] This invention is implemented as follows:

[0007] A method for preparing a hydrophilic ceftriaxone magnetic molecularly imprinted polymer, wherein the preparation method comprises: using a magnetic iron-aluminum mixed hydroxide as a carrier, ceftriaxone as a template molecule, 3-amino-1,2,4-triazole as a functional monomer, ethylene glycol dimethacrylate as a crosslinking agent, ammonium persulfate as an initiator, and water as a pore-forming agent to prepare a hydrophilic ceftriaxone magnetic molecularly imprinted polymer.

[0008] In some embodiments, the preparation method of the magnetic iron-aluminum mixed hydroxide is a co-precipitation method.

[0009] In some embodiments, (NH4)2Fe(SO4)2·6H2O and AlCl3·6H2O are added to deionized water and stirred until completely dissolved. NaOH is then added, the mixture is stirred to react, allowed to stand and separate into layers, the supernatant is discarded, and the black product is collected, which is the magnetic iron-aluminum mixed hydroxide.

[0010] In some embodiments, the molar ratio of (NH4)2Fe(SO4)2·6H2O to AlCl3·6H2O is 1.8-2.2:1.

[0011] In some embodiments, the specific steps of the preparation method include:

[0012] S1, prepare a magnetic iron-aluminum mixed hydroxide suspension;

[0013] S2, dissolve ceftriaxone and 3-amino-1,2,4-triazole in deionized water, and then mix and stir with a magnetic iron-aluminum mixed hydroxide suspension;

[0014] S3. Add ethylene glycol dimethacrylate and ammonium persulfate to the solution obtained in step S2, stir, and carry out the polymerization reaction of the mixture in an inert atmosphere. Remove the supernatant and collect the product, which is the hydrophilic ceftriaxone magnetic molecularly imprinted polymer.

[0015] In some embodiments, the ratio of the magnetic iron-aluminum mixed hydroxide, ceftriaxone, 3-amino-1,2,4-triazole, ethylene glycol dimethacrylate and ammonium persulfate is 8-12g:0.18-0.22mmol:3.5-4.5mmol:15-25mmol:1g.

[0016] In some embodiments, the polymerization reaction is carried out at a temperature of 38-42°C, a rotation speed of 280-330 r / min, and a reaction time of 4.5-5.5 h.

[0017] In some embodiments, the hydrophilic ceftriaxone magnetic molecularly imprinted polymer is further dried and then washed sequentially with a methanol-acetic acid-water mixture and a sodium dihydrogen phosphate solution until no template molecules are detected in the washing solution, and then dried for later use.

[0018] A hydrophilic ceftriaxone magnetic molecularly imprinted polymer prepared by the above method.

[0019] Application of the above-mentioned hydrophilic ceftriaxone magnetic molecularly imprinted polymer in the detection of ceftriaxone.

[0020] The beneficial effects of this invention are:

[0021] The hydrophilic ceftriaxone magnetic molecularly imprinted polymer of the present invention has high magnetization and more stable morphology, and exhibits good adsorption performance for ceftriaxone. It reaches adsorption equilibrium within 30 seconds, with an equilibrium adsorption capacity of 6.30 mg / g, which conforms to the pseudo-second-order kinetic adsorption model.

[0022] The hydrophilic ceftriaxone magnetic molecularly imprinted polymer of the present invention can be directly applied to the determination of cephalosporin antibiotics in aquatic environments, providing technical support for the subsequent development of highly selective hydrophilic magnetic dispersion solid-phase extraction adsorbents for ceftriaxone. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1XRD patterns of (A) MMH, (B) MNIP, and (C) CEF-MMIP for the examples and comparative examples.

[0025] Figure 2 FTIR plots of MMH, MNIP, and CEF-MMIP for examples and comparative examples.

[0026] Figure 3 Transmission electron microscopy (TEM) spectra of MMH (a), MNIP (b), and CEF-MMIP (c) for the examples and comparative examples.

[0027] Figure 4 The images show the scanning electron microscope (SEM) spectra of MMH (a), MNIP (b), and CEF-MMIP (c) for the examples and comparative examples.

[0028] Figure 5 Hysteresis loops of MMH, MNIP, and CEF-MMIP for examples and comparative examples.

[0029] Figure 6 The CEF-MMIP and MNIP adsorption isotherms are shown for the examples and comparative examples.

[0030] Figure 7 The Scatchard curves of CEF-MMIP and MNIP for the examples and comparative examples are shown.

[0031] Figure 8 The Langmuir model diagrams are for both the embodiment and the comparative example.

[0032] Figure 9 The Freundlich model diagrams are for both the example and comparative examples.

[0033] Figure 10 The kinetic adsorption curves of CEF-MMIP and MNIP are shown for the examples and comparative examples.

[0034] Figure 11 The diagram shows the first-order kinetic fit for the examples and comparative examples.

[0035] Figure 12 The figures show the second-order kinetic fitting diagrams for the examples and comparative examples. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention relates to a method for preparing a hydrophilic ceftriaxone magnetic molecularly imprinted polymer. The method includes the following steps: First, a magnetic iron-aluminum mixed hydroxide is selected as a carrier material, which exhibits good magnetic responsiveness and stability. Next, ceftriaxone is used as a template molecule, possessing a specific chemical structure and biological activity that guides polymer formation. Then, 3-amino-1,2,4-triazole is selected as a functional monomer, capable of specifically binding to the ceftriaxone molecule through hydrogen bonds or other interactions. Furthermore, ethylene glycol dimethacrylate is used as a crosslinking agent to ensure the stability and rigidity of the polymer network structure. Ammonium persulfate is used as an initiator to initiate a free radical polymerization reaction in aqueous solution, thereby forming a polymer network. Finally, water is used as a pore-forming agent to form a porous structure during polymerization, increasing the specific surface area and adsorption performance of the polymer. Through the above steps, a ceftriaxone magnetic molecularly imprinted polymer with excellent hydrophilicity and specific recognition ability can be successfully prepared.

[0038] In certain specific embodiments, the preparation of magnetic iron-aluminum mixed hydroxides can be achieved using a co-precipitation method. Specifically, in these embodiments, a certain amount of (NH4)2Fe(SO4)2·6H2O (ammonium iron sulfate) and AlCl3·6H2O (aluminum chloride hexahydrate) are dissolved in deionized water. Thorough stirring ensures that these salts are completely dissolved in the water. Subsequently, an appropriate amount of NaOH (sodium hydroxide) is added to the solution, and stirring continues to promote the reaction. After the reaction is complete, the mixture is allowed to stand to separate into layers, allowing the precipitate to be separated. Finally, the supernatant is discarded, and the remaining black precipitate is the desired magnetic iron-aluminum mixed hydroxide. This method can effectively prepare iron-aluminum mixed hydroxides with specific magnetic and chemical compositions, suitable for various industrial and scientific research applications.

[0039] In some embodiments, the molar ratio of (NH4)2Fe(SO4)2·6H2O to AlCl3·6H2O is 1.8-2.2:1. This molar ratio range ensures effective binding between the reactants, thereby achieving optimal chemical reaction results. By adjusting the ratio of these two compounds, the reaction process and the properties of the final product can be optimized.

[0040] In some embodiments, a method for preparing a hydrophilic ceftriaxone magnetic molecularly imprinted polymer includes the following detailed steps:

[0041] First, step S1 involves preparing a magnetic iron-aluminum mixed hydroxide suspension. Specifically, this suspension can be formed by dissolving the magnetic iron-aluminum mixed hydroxide in deionized water.

[0042] Next, step S2 involves dissolving ceftriaxone and 3-amino-1,2,4-triazole in deionized water. Ceftriaxone is a broad-spectrum antibiotic, while 3-amino-1,2,4-triazole is a commonly used small organic molecule. After dissolving these two substances, they are mixed with the previously prepared magnetic iron-aluminum mixed hydroxide suspension and stirred thoroughly to ensure that ceftriaxone and 3-amino-1,2,4-triazole are uniformly distributed in the suspension.

[0043] Then, step S3 involves adding ethylene glycol dimethacrylate and ammonium persulfate to the mixed solution obtained in step S2. Ethylene glycol dimethacrylate is a crosslinking agent capable of forming a stable polymer network structure with ceftriaxone and 3-amino-1,2,4-triazole. Ammonium persulfate acts as an initiator to initiate the polymerization reaction. After these substances are added, the mixture is stirred continuously, and the polymerization reaction is carried out under an inert atmosphere to prevent oxygen from interfering with the reaction. After the polymerization reaction is complete, the supernatant is removed, and the precipitate is collected, which is the desired hydrophilic ceftriaxone magnetic molecularly imprinted polymer.

[0044] Through the above steps, a hydrophilic ceftriaxone magnetic molecularly imprinted polymer with specific recognition sites can be successfully prepared. This polymer not only has good magnetic responsiveness, but can also effectively recognize and adsorb ceftriaxone molecules in an aqueous environment.

[0045] In some embodiments, the ratio of the magnetic iron-aluminum mixed hydroxide, ceftriaxone, 3-amino-1,2,4-triazole, ethylene glycol dimethacrylate, and ammonium persulfate is 8-12 g: 0.18-0.22 mmol: 3.5-4.5 mmol: 15-25 mmol: 1 g. This specific ratio ensures that the components react effectively during the preparation process to obtain the desired magnetic composite material. By precisely controlling the ratio of these components, the magnetic properties and adsorption performance of the material can be optimized, resulting in better performance in practical applications.

[0046] In some specific embodiments, the reaction temperature is set within the range of 38 to 42°C during the polymerization reaction. This temperature range helps ensure that the reaction proceeds under suitable conditions, preventing side reactions due to excessively high temperatures and avoiding negative impacts on the reaction rate and product formation efficiency due to excessively low temperatures. Simultaneously, the stirring speed of the reaction system is controlled at 280-330 revolutions per minute. This speed ensures thorough mixing of the reactants in the reaction system, thereby improving reaction uniformity and product consistency. Furthermore, the reaction time is set between 4.5 and 5.5 hours. This time range ensures that the reaction proceeds sufficiently, allowing the reactants to be converted into the target product as completely as possible, while avoiding unnecessary energy consumption and side reactions due to excessively long reaction times. In summary, by precisely controlling the reaction temperature, stirring speed, and time, polymerization reactions can be carried out effectively, yielding high-quality polymer products.

[0047] In some embodiments, the hydrophilic ceftriaxone magnetic molecularly imprinted polymer is further dried and then washed sequentially with a methanol-acetic acid-water mixture and a sodium dihydrogen phosphate solution until no template molecules are detected in the washing solution, and then dried for later use.

[0048] Embodiments of the present invention provide a hydrophilic ceftriaxone magnetic molecularly imprinted polymer prepared by a specific method. This polymer possesses unique hydrophilic properties, enabling it to effectively recognize and bind ceftriaxone molecules, thereby playing an important role in the detection and separation of ceftriaxone.

[0049] Specifically, embodiments of the present invention relate to a hydrophilic ceftriaxone magnetic molecularly imprinted polymer, which is obtained through an innovative preparation method. This method not only ensures the polymer's hydrophilicity but also endows it with the specific recognition ability of ceftriaxone molecules. This hydrophilic ceftriaxone magnetic molecularly imprinted polymer has broad application prospects in the detection and analysis of ceftriaxone.

[0050] Embodiments of the present invention also provide a method for applying the above-mentioned hydrophilic ceftriaxone magnetic molecularly imprinted polymer to the detection of ceftriaxone. By utilizing the specific binding ability of this polymer, high sensitivity and high selectivity in the detection of ceftriaxone can be achieved. This method not only improves the accuracy of detection but also simplifies the operation steps, and has high practical value.

[0051] Chemicals and reagents in the embodiments and comparative examples of this invention

[0052] Dimethyl ethylene glycol acrylate (EGDMA, GR grade, Guangdong Wengjiang Chemical Reagent Co., Ltd.); 3-amino-1,2,4-triazole (ATA, 96% purity, Shanghai Aladdin Reagent Co., Ltd.); ammonium persulfate (APS, 99.99% purity, Shanghai Aladdin Reagent Co., Ltd.); ferrous(II)ammonium sulfate hexahydrate (99.99% purity, Shanghai Aladdin Reagent Co., Ltd.); aluminum chloride hexahydrate (99.99% purity, Shanghai Aladdin Reagent Co., Ltd.); sodium hydroxide (AR grade, Xilong Scientific Co., Ltd.); sodium dihydrogen phosphate (AR grade, Xilong Scientific Co., Ltd.); acetonitrile (chromatographic grade, Merck, Germany), methanol (chromatographic grade, Fisher Scientific, UK), formic acid (AR grade, Merck, Germany) and glacial acetic acid (AR grade, Shanghai Aladdin Reagent Co., Ltd.).

[0053] Ceftriaxone sodium standard (97% purity, Shanghai Yuanye Biotechnology Co., Ltd.): Prepare a 1 mg / mL stock solution and store at -20°C protected from light. Thaw immediately before use and dilute proportionally to obtain the standard working solution.

[0054] Instruments and equipment of the embodiments and comparative examples of the present invention

[0055] The system includes a TSQAltisPlus high-performance liquid chromatography-tandem mass spectrometer with an electric spray ionization source (Thermo Fisher Scientific (FEI), USA), an IRAffinity-1 Fourier transform infrared spectroscopy scanner (Shimadzu Corporation, Japan), a NovaNanoSEM scanning electron microscope (Thermo Fisher Scientific (FEI), USA), a TalosF200s transmission electron microscope (Thermo Fisher Scientific (FEI), USA), a 7410 vibrating sample magnetometer (LakeShore, USA), an LC-ES-60SH mechanical stirrer (Shanghai Lichen Bangxi Instrument Technology Co., Ltd.), an MS3 vortex mixer (IKA GmbH, Germany), an LC-WB-2 constant temperature water bath (Shanghai Lichen Bangxi Instrument Technology Co., Ltd.), an MT008-C vacuum glove box (Changsha Miqi Instrument Equipment Co., Ltd.), and a DHG-9245A electric heating forced-air drying oven (Shanghai Yiheng Scientific Instrument Co., Ltd.), and a Milli-Q water purification system.

[0056] Example 1

[0057] Preparation of MMH

[0058] MMH was prepared by co-precipitation. 7.84 g (20 mmol) of (NH4)2Fe(SO4)2·6H2O and 2.41 g (10 mmol) of AlCl3·6H2O were added to 400 mL of deionized water and mechanically stirred until completely dissolved. 50 mL of 3 mol / L NaOH was quickly added, and the mixture was mechanically stirred at 500 rpm for 10 min. After the reaction was complete, the mixture was allowed to stand and separate into layers. The supernatant was discarded, and the black product was collected using a magnet. The product was washed three times with 400 mL of deionized water. The prepared iron-aluminum MMH was transferred to a 50 mL wide-mouth bottle, and an appropriate amount of deionized water (pH=7) was added to the upper layer. The mixture was stored at room temperature for later use.

[0059] Preparation of CEF-MMIP

[0060] Weigh 10 ± 0.02 g of the prepared iron-aluminum MMH into a 250 mL wide-mouth Erlenmeyer flask, add 100 mL of deionized water, and mechanically stir at 500 rpm for 10 min until completely dispersed to prepare an iron-aluminum MMH suspension. Separately, in a 250 mL conical flask, weigh 132.3 mg (0.2 mmol) of CEF and 336.3 mg (4 mmol) of ATA, dissolve them in 100 mL of deionized water, and add the dissolved CEF to the MMH suspension. Continue mechanical stirring for 30 min, then add 3.8 mL of the crosslinking agent EGDMA (20 mmol), continue stirring for 30 min, and then quickly add 1.00 g of APS to initiate the polymerization reaction. Transfer the mixture to a pre-filled nitrogen-filled vacuum glove box and polymerize at 40 °C in a water bath at 300 rpm for 5 h. After the reaction, discard the supernatant, collect the product, wash away unreacted template molecules from the product surface with deionized water, and dry at 80 °C to constant weight. The dried product was washed sequentially with methanol-acetic acid-water (6:1:3, V / V / V) and 0.15 mol / L sodium dihydrogen phosphate solution (pH=7) until no template molecules were detected in the washing solution. The product was then dried at 80°C for later use.

[0061] Comparative Example 1

[0062] Preparation of Magnetic Non-Molecularly Imprinted Polymers (MNIPs)

[0063] The preparation process of MNIP is the same as that of CEF-MMIP except that no template molecule is added.

[0064] Test Example 1

[0065] CEF-MMIP and MNIP characterization

[0066] X-ray diffraction (XRD)

[0067] Iron oxides have four crystal structures, among which γ-Fe₂O₃ and Fe₃O₄ have roughly the same crystal structure, both belonging to the inverse spinel structure. The XRD patterns of MMH, MNIP, and CEF-MMIP are shown below. Figure 1As shown in the figure. The XRD patterns show that all three samples exhibit diffraction peaks at 30.4°, 35.8°, 43.2°, 53.7°, 57.5°, and 63.1°, corresponding to the (220), (311), (400), (422), (511), and (440) crystal planes of γ-Fe₂O₃, respectively. The diffraction peaks at 21.3° and 36.8° correspond to the (110) and (311) crystal planes of γ-Al(OH)₃, respectively. The XRD results are highly consistent with those of γ-Fe₂O₃ (39-1346) and γ-Al(OH)₃ (7-0324), indicating that the products are fully crystalline γ-Fe₂O₃ and γ-Al(OH)₃. The results demonstrate that the molecularly imprinted layer was successfully coated onto the iron-aluminum MMH surface. Because MNIP and CEF-MMIP are covered with molecularly imprinted layers, the intensity of all diffraction peaks of MNIP and CEF-MMIP is weaker than that of iron-aluminum MMH, but the physical structure of the magnetic nano-oxide does not change during the polymerization process.

[0068] Fourier Transform Infrared Spectroscopy (FTIR)

[0069] The FTIR spectra of iron-aluminum MMH, MNIP, and CEF-MMIP are shown in Figure 2. (800 cm⁻¹) -1 The following absorption peaks are caused by the ferrite and aluminum oxy-oxide tensile and bending vibrations of the iron-aluminum MMH. The 3000–3700 cm⁻¹ peaks are... -1 The broad peak between 1630cm -1 The characteristic absorption peak at 3200-3500 cm⁻¹ is the OH bond vibration peak of water, as can be seen from the FTIR spectra of MNIP and CEF-MMIP. -1 Nearby (NH stretching), 1610~1660cm -1 (C=N) and 1318cm -1 1260cm -1 The peaks of (aromatic secondary amines) are all characteristic absorption peaks of ATA, while the 950 cm⁻¹ peak is... -1 860cm -1 The characteristic absorption peak is caused by the out-of-plane bending vibration of the triazole-substituted CH group, indicating that ATA participates in the polymerization reaction. (1728 cm⁻¹) -1 (C=O stretching) and 1100~1200cm -1 The characteristic absorption peaks of EGDMA (COC stretching) confirmed the presence of the crosslinking agent in the polymer. The peak shapes of MMIP and MNIP were essentially identical, with no significant difference, indicating that the main functional groups of CEF-MMIP and MNIP are consistent, and the template molecule ceftriaxone in CEF-MMIP was basically completely eluted. The infrared spectral results confirmed the successful preparation of the magnetically imprinted polymer CEF-MMIP.

[0070] Transmission electron microscopy (TEM) and scanning electron microscopy (SEM)

[0071] To further reveal the microscopic characteristics of these three materials, MMH, MNIP, and CEF-MMIP, high-resolution images of the polymers were obtained using transmission electron microscopy. Figure 3 TEM images of MMH, MNIP, and CEF-MMIP are shown. Their morphological characteristics were investigated using transmission electron microscopy. Figure 3 As shown in (a), particles of varying sizes and irregular shapes were observed in the TEM image of the MMH. Compared to Figure 3 Figures (a), (b), and (c) show an additional light gray outer layer, indicating that a polymer layer has been successfully prepared on the MMH surface.

[0072] SEM was used to further analyze the morphology and size of MMH, MNIP, and CEF-MMIP. Figure 4 As shown in (a), MMH exhibits a spherical morphology and is tightly aggregated. After polymerization ( Figure 4 b and 4c), MNIP and CEF-MMIP particles have irregular shapes and uneven sizes. CEF-MMIP ( Figure 4 c) The surface is relatively rough and has a loose, porous structure, which allows it to specifically adsorb CEF. Although the microstructure of the imprinted cavities on the CEF-MMIP surface cannot be observed by SEM, the rough surface of CEF-MMIP is likely due to the imprinted cavities left after CEF elution. Furthermore, the magnetic particle size of both MNIP and CEF-MMIP increases due to the formation of surface polymers.

[0073] Test Example 2

[0074] Magnetic property analysis

[0075] Under conditions of pH 7, temperature 25°C, and water as the dispersant, the superparamagnetism and saturation magnetization of MMH, MNIP, and CEF-MMIP were measured using a vibrating sample magnetometer, and the results are expressed as hysteresis loops. Simultaneously, the magnetic separation effect after CEF-MMIP adsorption was photographed. The scanning speed of the vibrating sample magnetometer was 1 degree per minute, with a step size of 0.02 degrees.

[0076] Figure 5The hysteresis loops (VSMs) of the prepared MMH, MNIP, and CEF-MMIP are shown in the figures. It can be observed from the figures that all tested materials exhibit a centrosymmetric state, a common characteristic of ferromagnetic materials. Further analysis reveals the presence of saturation magnetization and hysteresis loops in the curves, both important features indicating that the prepared MMH, MNIP, and CEF-MMIP possess superparamagnetic properties. Superparamagnetism is a special magnetic state that allows these materials to be rapidly attracted to a magnet under the influence of an external magnetic field and to quickly lose magnetism after the external magnetic field is removed. Specifically, the magnetizations of MMH, MNIP, and CEF-MMIP are 8.4, 3.6, and 2.3 emu / g, respectively (the magnetic materials were not sieved using a standard inspection sieve). This indicates that the magnetic strength of the material gradually decreases with the increase of the polymer shell structure. This decrease can be attributed to the shielding effect of the polymer shell on the MMH surface; that is, the presence of the polymer shell weakens the material's response to an external magnetic field. Figure 5 As can be seen, CEF-MMIP can be uniformly dispersed in water, which facilitates its application in solution systems. Despite its relatively weak magnetization, CEF-MMIP can achieve rapid separation within 30 seconds under the influence of an external magnetic field. This result fully demonstrates that the polymer possesses good magnetic properties, meeting the rapid separation requirements in practical applications.

[0077] Test Example 3

[0078] Static adsorption

[0079] Weigh 5 ± 0.02 mg of CEF-MMIP and MNIP into 50 mL centrifuge tubes, add 10 mL of 1–5 μg / mL ceftriaxone standard solution, and vortex for 30 s. Filter the supernatant through a 0.22 μm filter membrane and detect by HPLC-MS / MS. Perform three parallel determinations and calculate the adsorption capacity Q. The adsorption capacity calculation formula (1) is as follows:

[0080] Q = V(C0 - C) e ) / m(1)

[0081] Where V (mL) is the volume of the solution, m (mg) is the mass of the adsorbent, and C0 and C... e (μg / mL) represent the initial concentration and equilibrium concentration of the solution, respectively.

[0082] The Scatchard calculation formula (2) is as follows:

[0083] Q / C e =-Q / K D +Q max / K D (2)

[0084] Where Q (mg / g) is the adsorption capacity at equilibrium, and C e (μg / mL) is the equilibrium concentration, K D Q is the dissociation constant. max (mg / g) represents the apparent maximum adsorption capacity.

[0085] The calculation formulas for the Langmuir (Equation 3) and Freundlich (Equation 4) isothermal adsorption models are as follows:

[0086] C e / Q e =C e / Q max +1 / (K L Q max (3)

[0087] lnQ e =1 / nlnC e +lnK F (4)

[0088] Where 1 / n represents Freundlich's empirical coefficient, K L (L / mg) represents the Langmuir constant, K F (L / g) represents Freundlich's constant, Q (mg / g) is the amount of ceftriaxone bound, Q max (mg / g) Maximum binding amount under equilibrium conditions, C e (μg / mL) represents the equilibrium concentration of MMIP and MNIP.

[0089] To further investigate the binding performance of CEF-MMIP and MNIP, static adsorption experiments were conducted. Under isothermal conditions, the adsorption amounts of CEF-MMIP and MNIP in ceftriaxone standard solutions of different mass concentrations were measured. The experimental results are as follows: Figure 6As shown in the figure, the adsorption capacities of both CEF-MMIP and MNIP steadily increased with increasing CEF concentration in the solution. It can be observed from the figure that the adsorption capacity of CEF-MMIP was consistently higher than that of MNIP, mainly due to its unique imprinted sites, which specifically recognize and tightly bind to target molecules. When the CEF concentration reached 4 μg / mL, the adsorption of CEF-MMIP reached saturation. As the CEF concentration gradually increased, the number of target molecules adsorbed by the imprinted sites of CEF-MMIP also increased. Especially in the concentration range of 1–3 μg / mL, its adsorption capacity increased rapidly, demonstrating highly efficient adsorption characteristics. However, with further increases in the initial concentration, the steric hindrance effect between the target molecules and the magnetic material gradually became apparent, causing the rate of increase in adsorption to slow down until a stable adsorption equilibrium was reached. In contrast, MNIP, lacking specific imprinted sites, could only perform non-specific adsorption, thus its adsorption effect was much lower than that of CEF-MMIP. This comparison further highlights the advantage of CEF-MMIP in specific adsorption.

[0090] To thoroughly evaluate the binding properties and number of binding sites of CEF-MMIP, a detailed analysis was conducted using the Scatchard model. This was achieved through observation and analysis. Figure 7 The data clearly shows that the CEF-MMIP Scatchard plot exhibits two distinct straight lines, each composed of two linear segments with different slopes. This phenomenon indicates that the binding sites of CEF-MMIP are heterogeneous, corresponding to both high-affinity specific binding sites and low-affinity non-specific binding sites. To further quantify the characteristics of these binding sites, K was calculated. D Value (dissociation constant) and Q max Value (maximum binding amount). For CEF-MMIP, the K value of its high-affinity and low-affinity binding sites. D The values ​​were 0.052 and 0.082 mg / L, respectively, while the corresponding Q... max The values ​​were 4.48 and 6.74 mg / g, respectively. Meanwhile, the same Scatchard analysis was performed on MNIP. Unlike the complex graph of CEF-MMIP, the Scatchard plot of MNIP showed only a straight line, indicating that its binding sites are relatively homogeneous and lack specificity. The K0 of MNIP was calculated. D and Q max The values ​​were 0.14 mg / L and 3.16 mg / g, respectively. Comparison of the Scatchard analysis results of CEF-MMIP and MNIP revealed that CEF-MMIP had a lower Kc. D Value and higher Qmax This clearly demonstrates that CEF-MMIP exhibits a stronger specific adsorption capacity for ceftriaxone compared to MNIP. These results provide important guidance for the further development and application of CEF-MMIP in the separation, purification, and detection of antibiotics such as ceftriaxone.

[0091] Building upon previous research, to further explore the mechanism of static adsorption, a detailed analysis was conducted using the Langmuir and Freundlich isotherm adsorption models. The results are as follows: Figure 8 , 9 As shown. Both models are classic adsorption models, providing a deeper understanding of the interaction between the adsorbent and the target molecule. From Figure 8 As can be seen, the points in the figure closely surround the fitted line, indicating a good fit. Simultaneously, relevant adsorption parameters were calculated, and these data are summarized in Table 1 for subsequent analysis and comparison. From the perspective of goodness of fit, the adsorption behavior of CEF-MMIP better conforms to the Langmuir adsorption isotherm model, with R0... 2 The value reached 0.9991, close to 1, indicating that the experimental data and model predictions were in good agreement. This finding means that the adsorption of ceftriaxone by the prepared CEF-MMIP is mainly monolayer adsorption, that is, ceftriaxone molecules form a uniform adsorption layer on the surface of CEF-MMIP, rather than forming multilayer stacking. In the Langmuir model, K L The value of K is an important parameter, representing the strength of adsorption capacity. Specifically, K... L The higher the K value, the stronger the adsorption capacity of the adsorbent for the target molecule. By comparing the K values ​​of CEF-MMIP and MNIP... L Value, discover the K value of CEF-MMIP L The value was 12.72, significantly higher than MNIP's 5.94. This substantial difference further confirms that CEF-MMIP has a stronger adsorption capacity for ceftriaxone, mainly due to its unique imprinting sites and highly specific recognition mechanism.

[0092] Table 1. Fitting parameters for the adsorption isotherms of CEF-MMIP and MNIP

[0093]

[0094] Test Example 4

[0095] Dynamic adsorption

[0096] Weigh 5 ± 0.02 mg of CEF-MMIP and MNIP into 50 mL centrifuge tubes, add 10 mL of 5 μg / mL ceftriaxone standard solution, and vortex for 10, 20, 30, 40, 50, 60, and 70 s, respectively, and separate using an external magnetic field. Filter the supernatant through a 0.22 μm filter membrane and detect by HPLC-MS / MS. Perform the determination in triplicate and calculate the adsorption capacity Q.

[0097] To further evaluate the adsorption mechanism, the adsorption kinetics of ceftriaxone on CEF-MMIP and MNIP were investigated. The experimental data were fitted using two of the most common kinetic models: pseudo-first-order equations and pseudo-second-order equations. The mathematical expressions for these two models are shown in equations (5) and (6).

[0098] ln(Q e -Q t )=lnQ e -k1t(5)

[0099] t / Q t =1 / k2Q e 2 +t / Q e (6)

[0100] Among them, Q e and Q t K1 represents the amount of ceftriaxone adsorbed on CEF-MMIP and MNIP at equilibrium and at time t (min), respectively (mg / g), and K2 represents the first-order rate constant and the second-order rate constant (g / mg / min).

[0101] like Figure 10As shown, the kinetic adsorption curves of CEF-MMIP and MNIP change with increasing adsorption time. Both curves exhibit a trend of initial gradual increase followed by stabilization, reflecting the adsorption process from rapid initial adsorption to adsorption equilibrium. Notably, both adsorbents reach adsorption equilibrium within 30 seconds, indicating very fast adsorption rates. However, under the same conditions, CEF-MMIP exhibits a higher adsorption capacity than MNIP, thanks to its unique imprinted cavity structure, which allows for more efficient capture and binding of ceftriaxone molecules. In the initial stage of adsorption, ceftriaxone molecules are rapidly adsorbed by a large number of available imprinted cavities on the CEF-MMIP surface, resulting in a very fast adsorption rate. As adsorption progresses, by the middle stage, most of the imprinted cavities are occupied, hindering the diffusion of ceftriaxone molecules within CEF-MMIP and thus gradually slowing the adsorption rate. When adsorption reaches equilibrium, most of the imprinted cavities on the CEF-MMIP surface are occupied by ceftriaxone molecules. At this point, a repulsive force is generated between the ceftriaxone molecules adsorbed on CEF-MMIP and the remaining ceftriaxone molecules in the solution. This repulsive force makes it difficult for ceftriaxone molecules in the solution to be adsorbed onto CEF-MMIP again. Therefore, the adsorption amount remains essentially constant during this stage, reaching a stable equilibrium. This process fully demonstrates that CEF-MMIP, as a highly efficient and specific adsorbent, has significant advantages and application potential in the adsorption and separation of ceftriaxone.

[0102] The kinetic fitting results of the adsorption behavior of CEF-MMIP and MNIP on CEF are as follows: Figure 11 , 12 As shown in the figure. Comparative analysis revealed that the correlation coefficients of the pseudo-second-order adsorption kinetic models for CEF-MMIP and MNIP were significantly higher than those for the pseudo-first-order adsorption kinetic model. This indicates that the pseudo-second-order model more accurately describes the adsorption behavior of ceftriaxone by these two adsorbents. The equilibrium adsorption capacity Q was then calculated based on the model. e For CEF-MMIP and MNIP, the values ​​were 6.19 and 2.94 mg / g, respectively (detailed data are shown in Table 2). These calculated values ​​are very close to the actual adsorption amounts observed in the experiment, further validating the accuracy of the pseudo-second-order adsorption kinetic model. This indicates that the adsorption of ceftriaxone by CEF-MMIP is mainly based on a chemisorption mechanism, rather than simple physisorption. This chemisorption involves chemical bonding between the adsorbent and the target molecule, thus exhibiting stronger binding force and higher selectivity. Simultaneously, this also means that mass transfer processes in solution are not involved during adsorption, thereby further improving adsorption efficiency and stability.

[0103] Although the saturated adsorption capacity of CEF-MMIP prepared in this embodiment of the invention is relatively low, it still meets the detection requirements of actual samples. Compared with previous preparation methods, the material prepared in this embodiment of the invention requires only 30 seconds to reach equilibrium, which is significantly better than existing research and meets the requirements for rapid detection. Furthermore, this embodiment of the invention uses water as a porogen, reducing the amount of organic solvent used, lowering costs, and mitigating environmental pollution.

[0104] Table 2 Adsorption kinetic fitting parameters

[0105]

[0106] In summary, this invention uses MMH as a carrier, CEF as a template molecule, ATA as a functional monomer, EGDMA as a crosslinking agent, APS as an initiator, and water as a porogen to prepare a hydrophilic magnetic molecularly imprinted polymer for the selective enrichment of ceftriaxone. Characterization and adsorption experiments demonstrated that the synthesized hydrophilic CEF-MMIP has specific recognition sites, exhibits a rapid adsorption rate, and reaches adsorption equilibrium within 30 seconds. The equilibrium adsorption capacity of CEF-MMIP is 6.30 mg / g, and its adsorption of CEF conforms to a pseudo-second-order kinetic model, indicating that the adsorption behavior is primarily chemisorption. Magnetic property analysis showed that CEF-MMIP can be rapidly separated under a magnetic field without the need for cumbersome centrifugation or filtration. Therefore, this magnetic molecularly imprinted polymer can be used as a magnetic adsorbent for the rapid and selective enrichment and separation of CEF in food testing. Furthermore, this preparation method has advantages such as low cost, hydrophilicity, and green synthesis, and has broad application prospects.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a hydrophilic ceftriaxone magnetic molecularly imprinted polymer, characterized in that, The preparation method is as follows: using magnetic iron-aluminum mixed hydroxide as a carrier, ceftriaxone as a template molecule, 3-amino-1,2,4-triazole as a functional monomer, ethylene glycol dimethacrylate as a crosslinking agent, ammonium persulfate as an initiator, and water as a pore-forming agent, a hydrophilic ceftriaxone magnetic molecular imprinted polymer is prepared. The specific steps include: S1, prepare a magnetic iron-aluminum mixed hydroxide suspension; S2, dissolve ceftriaxone and 3-amino-1,2,4-triazole in deionized water, and then mix and stir with a magnetic iron-aluminum mixed hydroxide suspension; S3, add ethylene glycol dimethacrylate and ammonium persulfate to the solution obtained in step S2, stir, and carry out the polymerization reaction of the mixed product in an inert atmosphere. Remove the supernatant and collect the product, which is the hydrophilic ceftriaxone magnetic molecularly imprinted polymer. The amounts of the magnetic iron-aluminum mixed hydroxide, ceftriaxone, 3-amino-1,2,4-triazole, ethylene glycol dimethacrylate, and ammonium persulfate are 10g±0.02g, 0.2mmol, 4mmol, 20mmol, and 1g, respectively. The polymerization reaction was carried out at a temperature of 40°C, a rotation speed of 300 r / min, and a reaction time of 5 h. The hydrophilic ceftriaxone magnetic molecularly imprinted polymer was dried and then washed sequentially with a methanol-acetic acid-water mixture and a sodium dihydrogen phosphate solution until no template molecules were detected in the washing solution, and then dried for later use. The hydrophilic ceftriaxone magnetic molecularly imprinted polymer reaches adsorption equilibrium within 30 seconds.

2. The preparation method according to claim 1, characterized in that, The magnetic iron-aluminum mixed hydroxide is prepared by co-precipitation.

3. The preparation method according to claim 2, characterized in that, Add (NH4)2Fe(SO4)2·6H2O and AlCl3·6H2O to deionized water, stir until completely dissolved, add NaOH, stir to react, let stand to separate into layers, discard the supernatant, and collect the black product, which is the magnetic iron-aluminum mixed hydroxide.

4. The preparation method according to claim 3, characterized in that, The molar ratio of (NH4)2Fe(SO4)2·6H2O to AlCl3·6H2O is 1.8-2.2:

1.

5. A hydrophilic ceftriaxone magnetic molecularly imprinted polymer prepared by the method of any one of claims 1 to 4.

6. The application of the hydrophilic ceftriaxone magnetic molecularly imprinted polymer of claim 5 in the detection of ceftriaxone.

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