Preparation method of a hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent and its application in selective separation of adenosine monophosphate

Abstract

The present invention belongs to the technical field of preparing functional materials for molecular recognition, adsorption and separation, and discloses a method for preparing a hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent and its application in the selective separation of adenosine monophosphate. The present invention targets the structural characteristics of a typical nucleoside compound adenosine monophosphate (AMP) molecule, designs and synthesizes Zr-MOFs nanosheets coordinated with its specific metal ion as a matrix material, and uses 5-(2-methoxyvinyl)-2′-deoxyuridine (AcrU) as a functional monomer that undergoes specific base complementary pairing. The arrangement and orientation of the template molecules are precisely fixed through an ordered assembly strategy. Finally, the large number of double bonds modified on the surface of the Zr-MOFs nanosheets and a hydrophilic cross-linking agent are utilized to photoinitiate the construction of a stable hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent (D-MIPs), thereby enhancing the recognition and separation effect of nucleoside compounds and achieving the selective separation and enrichment of nucleoside compounds such as AMP in biological samples such as urine and blood.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of molecular recognition adsorption and separation functional materials, and specifically relates to a preparation method of a hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent and its application in selectively separating adenosine monophosphate. Background Art

[0002] Nucleoside compounds are a class of water-soluble components with a wide range of physiological activities, primarily encompassing three categories: bases, nucleosides, and nucleotides. Nucleotides are the fundamental building blocks of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), possessing numerous important biological functions and participating in the retention, replication, and transcription of genetic information in virtually all biological cells. Nucleoside compounds are also crucial raw materials for biochemical drug development and genetic engineering research, as well as important intermediates for the production of antibacterial, antitumor, antiviral, antifungal, and immunomodulatory nucleoside drugs. Therefore, the development and research of nucleoside compounds holds immense economic, social, and scientific significance for biomedicine and human health. Currently, the primary sources of nucleoside compounds are nucleic acid degradation, chemical synthesis, and biotransformation. However, these methods still suffer from common challenges, such as complex product matrices, low concentrations of the main product, and numerous byproducts. Therefore, there is an urgent need to find suitable methods for separating and enriching nucleoside compounds from these complex products. Currently, numerous methods are commonly used to separate nucleoside compounds, including crystallization, high-performance liquid chromatography (HPLC), column chromatography, solvent extraction, and adsorption. Adsorption is a widely applicable, highly efficient, and environmentally friendly method. Typical nucleoside compounds, such as adenosine monophosphate (AMP), possess specialized functional groups, such as cis-dihydroxyl groups, phosphate groups, and bases. These specialized functional groups can be selectively adsorbed and separated by specific groups, potentially exploiting their affinity for these functional groups.

[0003] Molecular imprinting is a method that mimics the specific binding mechanism between enzymes and substrates or antigens and antibodies, achieving highly selective recognition of specific targets. It has been called an "artificial antibody" that mimics life processes. Therefore, achieving precise imprinting requires further exploration of biological processes, such as the dual receptor phenomenon. Dual receptors are a common physiological or pharmacological behavior, often seen when multiple amino acids simultaneously interact with the same neurotransmitter, hormone, drug, or toxin to enhance specific binding. In recent years, researchers have utilized covalent or noncovalent interactions, based on a dual receptor strategy, to construct polymers that enhance the selectivity of imprinted recognition sites. This dual receptor interaction immobilizes the same target molecule, improving site affinity. However, during the preassembly process, competition and interference between two or more functional monomers and the template molecule can easily occur. Therefore, to reduce the nonspecificity of direct blending of multiple functional monomers and improve the utilization of the dominant functional monomer, controlled imprinting through ordered assembly is key to achieving precise recognition.

[0004] Metal-organic frameworks (MOFs) are a type of coordination polymer that has rapidly developed in recent years. They are novel porous materials with three-dimensional pore structures synthesized using metal ions as connecting points and organic ligands as a framework. Two-dimensional MOF nanosheets are an emerging class of ultrathin porous nanosheets. Their large surface area, tunable porosity, excellent stability, and strong adsorption capacity hold great potential for applications in separation, catalysis, and pharmaceutical matrix applications. However, the recognition performance of traditional MOFs as adsorbents needs to be further improved. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method for preparing an orderly assembled hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent to accurately control the imprinting process and enhance the identification and separation effect of nucleoside compounds, and uses it for the selective adsorption and separation of the nucleoside compound AMP.

[0006] Based on the structural characteristics of the nucleoside compound AMP, the present invention designs and synthesizes Zr-MOFs nanosheets coordinated with its specific metal ions as the matrix material, and 5-(2-methoxyvinyl)-2′-deoxyuridine (AcrU) that undergoes specific base complementary pairing as the functional monomer. The arrangement and orientation of the template molecules are precisely fixed through an ordered assembly strategy. Finally, the large number of double bonds and hydrophilic cross-linkers modified on the surface of the Zr-MOFs nanosheets are used to photoinitiate the construction of stable hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbents (D-MIPs), thereby enhancing the recognition and separation effect of nucleoside compounds.

[0007] The present invention first prepares hydrophilic Zr-MOFs nanosheets (Zr-BTB-PABA) by a hydrothermal method, and then uses the amino groups on the nanosheets to react with methacrylic anhydride to obtain nanosheets (D-PABA) with a large number of double bonds modified on the surface; the template molecule and the functional monomer AcrU are preassembled for the first time through specific base complementary pairing, and then the synthesized D-PABA matrix material is added, and the Zr on the Zr-MOFs nanosheets is used to form a double bond-modified nanosheet. 4+ PO4 with AMP 3- Specific metal coordination occurs, and a second pre-assembly is performed to fix the arrangement and spatial orientation of the template molecules; finally, dual-receptor hydrophilic MOFs nanosheet surface imprinted adsorbents (D-MIPs) are prepared by photoinitiated polymerization to achieve selective adsorption and separation of AMP.

[0008] In order to achieve the above technical purpose, the technical solution adopted by the present invention is:

[0009] The present invention provides a method for preparing ordered assembled hydrophilic dual-receptor MOF nanosheet surface imprinted adsorbents (D-MIPs). The selective adsorption and separation performance of the D-MIPs adsorbents for AMP molecules was evaluated using an AMP simulated solution. The method comprises the following steps:

[0010] (1) Preparation of Zr-BTB-PABA:

[0011] A mixture of zirconium chloride ZrCl4 and 1,3,5-tris(4-carboxyphenyl)benzene H3BTB was dissolved in N,N-dimethylformamide (DMF), and formic acid and deionized water were added after ultrasonication. The ultrasonic mixing was continued to obtain a mixed solution A, and then the mixed solution A was placed in a reactor for hydrothermal reaction. After cooling to room temperature, the solid was centrifuged to obtain a white solid, which was washed several times with DMF and ethanol and dried in vacuo to obtain zirconium MOF nanosheets with carboxyl groups, namely Zr-BTB-FA.

[0012] Subsequently, Zr-BTB-FA nanosheets were dispersed in DMF, and 4-aminobenzoic acid PABA was added to DMF and ultrasonically dissolved. The PABA solution was added to the Zr-BTB-FA dispersion to obtain a mixed solution B. The mixed solution B was heated, condensed, and refluxed for reaction, then cooled to room temperature. The light yellow product was collected by centrifugation, washed several times with DMF and ethanol, and vacuum dried to obtain zirconium MOFs nanosheets with amino groups, namely Zr-BTB-PABA.

[0013] (2) Preparation of D-PABA:

[0014] Zr-BTB-PABA nanosheets were dispersed in dichloromethane, and methacrylic anhydride and triethylamine were added to obtain a mixed solution C. The mixed solution C was heated and condensed under reflux. After the reaction was completed, the mixture was cooled to room temperature, and the product was collected by centrifugation, washed several times with dichloromethane, and vacuum dried to obtain D-PABA nanosheets.

[0015] (3) Preparation of D-MIPs:

[0016] First, the template molecule AMP was dissolved in a Tris-HCl buffer solution (pH = 7.4, 50 mM), and the functional monomer AcrU was added. N2 was passed through the solution at room temperature to remove oxygen, and the first pre-assembly was performed based on base complementary pairing in a light-proof environment.

[0017] Subsequently, D-PABA nanosheets were added, and N2 was passed through the reaction mixture to remove oxygen at room temperature. A second pre-assembly was performed based on metal ion coordination under light-proof stirring. The cross-linker N,N'-methylenebisacrylamide MBAA was then added, and N2 was continued to be passed through the reaction mixture to remove oxygen. The photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone was added, and N2 was continued to be passed through the reaction mixture to remove oxygen. After photopolymerization was initiated by UV irradiation, the ultraviolet light wavelength was λ = 254 nm, and the product D-MIPs was collected by centrifugation. The D-MIPs were then eluted with a mixed solution of methanol / acetic acid (9:1, V:V) as an eluent to remove unreacted template molecules and organic solvents until no AMP molecules were detected in the eluent. Finally, the product D-MIPs were dried in vacuum.

[0018] At the same time, referring to the above method, but without adding the template molecule AMP before photoinitiated polymerization, hydrophilic MOFs surface non-imprinted nanosheet adsorbents (D-NIPs) were prepared as a reference for adsorption performance research.

[0019] In the mixed solution A of step (1), the dosage ratio of ZrCl4, H3BTB, DMF, formic acid and deionized water is 1.0 mg: (0.8-0.9) mg: (0.3-0.5) mL: (0.07-0.08) mL: (4.5-5.0) μL; the hydrothermal reaction temperature is 110°C-130°C, and the hydrothermal reaction time is 36-60 h;

[0020] In the mixed solution B of step (1), the mass ratio of Zr-BTB-FA to PABA is 1.0 mg:(9.5-10.5) mg, the concentration of Zr-BTB-FA in the mixed solution is 1.67-2.5 mg / mL, and the concentration of PABA is 16.67-25 mg / mL;

[0021] The temperature of the condensation reflux reaction is 140°C-160°C, and the time is 60h-84h;

[0022] In the mixed solution C of step (2), the amount ratio of Zr-BTB-PABA, dichloromethane, methacrylic anhydride and triethylamine is 1.0 g: (450-550) mL: (36-37) mL: (2.7-2.8) mL; the condensation reflux temperature is 50-60 ° C, and the time is 12h-36h;

[0023] In step (3), the ratio of AMP, AcrU, D-PABA, MBAA and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is 1.0 mmol: (1.0-2.0) mmol: (150-250) mg: (1.0-1.5) g: (0.08-0.10) g; the concentration of AMP in the Tris-HCl buffer solution is 4.55*10 -3 ~5.56*10 -3 mol / L.

[0024] In step (3), the photoinitiated polymerization time is 4.0-12 hours, the reaction temperature is 25-40° C., and the time for the first pre-assembly and the second pre-assembly are both 12 hours.

[0025] The vacuum drying temperature described in the technical solution is 45°C.

[0026] The hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent prepared by the present invention is used for selectively separating adenosine monophosphate.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The present invention designs and synthesizes hydrophilic Zr-BTB-PABA nanosheets based on the structural characteristics of AMP molecules by hydrothermal reaction, reacts the amino groups on the nanosheets with methacrylic anhydride to obtain D-PABA with a large number of double bonds modified on the surface and uses it as a matrix material, then uses the good base complementary pairing effect of AMP and AcrU to perform the first pre-assembly, and then adds Zr of the hydrophilic D-PABA matrix material. 4+ Compatible with AMP's PO4 3- The metal ion coordination occurs for the second pre-assembly. Through the orderly two assemblies, the arrangement and orientation of the template molecules are precisely fixed. Finally, water-soluble MBAA is used as a cross-linker to photoinitiate the construction of a hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent to enhance the imprinting recognition and separation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1These are the SEM images of the Zr-BTB-FA (a) and Zr-BTB-PABA nanosheets (b) prepared in Example 1 after ultrasonic treatment in ethanol for 30 min (a1, b1), as well as the SEM images of the Zr-BTB-FA (a) and Zr-BTB-PABA nanosheets (b) after immersion in acetic acid (a2, b2), methanol (a3, b3), a mixed solution of methanol / acetic acid (9:1, V:V) (a4, b4), and DMSO (a5, b5), respectively, for 5 days.

[0030] Figure 2 SEM images of D-PABA nanosheets prepared in Example 1 (a1 and a2), and SEM images of D-MIPs prepared with different photoinitiated polymerization times of 4.0 h (b1 and b2), 8.0 h (c1 and c2), and 12 h (d1 and d2).

[0031] Figure 3 Water contact angles of Zr-BTB-FA (a), D-PABA (b) and D-MIPs (c) prepared in Example 1.

[0032] Figure 4 2 are the XRD spectra of Zr-BTB-FA, D-PABA and D-MIPs prepared in Example 1.

[0033] Figure 5 BET analysis of D-PABA (a) and D-MIPs (b) prepared in Example 1.

[0034] Figure 6 This is an analysis of the effects of different ratios of template molecules to functional monomers and photopolymerization time prepared in Experimental Example 1 on the adsorption capacity and imprinting factor of the adsorbent.

[0035] Figure 7 The kinetic data and model fitting curves of AMP adsorption by D-MIPs, D-NIPs and D-PABA prepared in Experimental Example 2 at 298K.

[0036] Figure 8 These are the equilibrium data and model fitting curves of AMP adsorption by D-MIPs, D-NIPs and D-PABA prepared in Experimental Example 3 at 288, 298 and 308 K.

[0037] Figure 9 These are the single-component adsorption results of AMP, dA, dG, ADP, ATP, and dC by D-MIPs and D-NIPs prepared in Experimental Example 4. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific embodiments and drawings.

[0039] In the specific implementation of the present invention, the recognition performance evaluation is performed according to the following method:

[0040] The ratio of template molecule to functional monomer, as well as the illumination time required to form the imprinted polymer, were optimized. Comparative adsorption studies were then conducted on imprinted and non-imprinted adsorbents prepared under the same conditions. The optimal reaction ratio of functional monomer to template molecule and the optimal photopolymerization time were determined based on the equilibrium adsorption capacity and imprinting factor.

[0041] 2.0 mL of a certain concentration of AMP solution was added to a 10 mL centrifuge tube (the solvent was a pH = 7.4, 50 mM Tris-HCl buffer solution), and a certain amount of D-MIPs, D-NIPs and D-PABA composite adsorbent was added. The solution was placed in a constant temperature water bath at different temperatures and shaken for a certain period of time. The solution was filtered with a microporous nitrocellulose membrane (pore size of 0.22 μm). The AMP concentration in the filtrate was detected by UV-vis at a wavelength of 259 nm, and the adsorption capacity was calculated based on the results. 2.0 mL of AMP with an initial concentration of 300 μmol / L was added. The solution was added to a 10mL centrifuge tube, and a certain amount of D-MIPs, D-NIPs and D-PABA composite adsorbent was added. The adsorbents were taken out at a certain gradient time, and the adsorption capacity was calculated based on the results to study the kinetic properties of the D-MIPs adsorbent. Several nucleoside compounds with similar structures and properties to AMP, such as 2-deoxyguanosine (dG), 2-deoxycytidine (dC) and 2′-deoxyadenosine (dA), adenosine diphosphate (ADP) and adenosine triphosphate (ATP), were selected as selective adsorption molecules to study the selective discrimination performance of the adsorbent.

[0042] The present invention will be further described below with reference to specific implementation examples.

[0043] Example 1:

[0044] (1) Preparation of Zr-BTB-PABA:

[0045] A mixture of 12.5 mg of ZrCl₄ and 10.12 mg of H₃BTB was dissolved in 5.0 mL of DMF. The mixture was sonicated for 10 minutes, followed by the addition of 0.910 mL of formic acid and 60 μL of deionized water. After sonication, the mixture was hydrothermally reacted in a reactor at 120°C for 48 hours. After cooling to room temperature, the solid was centrifuged to obtain a white solid. The solid was washed three times with DMF and ethanol, and then dried in vacuo at 45°C to obtain zirconium MOF nanosheets with carboxyl groups (Zr-BTB-FA).

[0046] Subsequently, 100 mg of Zr-BTB-FA nanosheets were dispersed in 30 mL of DMF (DMF1). 1000 mg of PABA was then added to 20 mL of DMF (DMF2) and ultrasonically dissolved. The mixture was then added to the Zr-BTB-FA dispersion. After reflux at 150°C for 72 hours, the mixture was cooled to room temperature and centrifuged to obtain the pale yellow product. The product was washed three times with DMF and ethanol and dried in vacuo at 45°C to obtain the amino-bearing zirconium MOF nanosheets (Zr-BTB-PABA).

[0047] (2) Preparation of D-PABA:

[0048] 0.1 g of Zr-BTB-PABA nanosheets were dispersed in 50 mL of dichloromethane, and 3.691 mL of methacrylic anhydride and 0.279 mL of triethylamine were added. The mixture was heated at 55 °C for 24 h under condensation reflux. After the reaction, the mixture was cooled to room temperature, the product was collected by centrifugation, washed three times with dichloromethane, and dried in vacuo at 45 °C to obtain D-PABA nanosheets.

[0049] (3) Preparation of D-MIPs:

[0050] First, 0.1 mmol of the template molecule AMP was dissolved in 20 mL of Tris-HCl buffer solution (pH = 7.4, 50 mM), and 0.15 mmol of AcrU was added. The solution was deoxygenated by nitrogen flow at room temperature and pre-assembled for 12 h based on base complementary pairing in a dark environment. Subsequently, 20 mg of D-PABA nanosheets were preassembled for a second time under N2 deoxygenation at room temperature, with stirring in the dark, based on metal ion coordination. 0.1156 g of the crosslinker N,N'-methylenebisacrylamide (MBAA) was then added, and N2 deoxygenation was removed. 0.009 g of the photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone was added, and N2 deoxygenation was removed. Photopolymerization was initiated at 35°C using a UV lamp (UV wavelength λ = 254 nm) for 4 h. The resulting D-MIPs were collected by centrifugation. The D-MIPs were then eluted with a methanol / acetic acid (9:1, v:v) mixture to remove unreacted template molecules and organic solvent until no AMP molecules were detected in the eluate. Finally, the resulting D-MIPs were dried in vacuo at 45°C.

[0051] At the same time, referring to the above method, but without adding the template molecule AMP before photoinitiated polymerization, hydrophilic MOFs surface non-imprinted nanosheet adsorbents (D-NIPs) were prepared as a reference for adsorption performance research.

[0052] Figure 1The following are SEM images of the Zr-BTB-FA (a) and Zr-BTB-PABA (b) nanosheets prepared in Example 1, ultrasonicated in ethanol for 30 minutes (a1, b1), and SEM images of the Zr-BTB-FA (a) and Zr-BTB-PABA (b) nanosheets after immersion in acetic acid (a2, b2), methanol (a3, b3), a methanol / acetic acid (9:1, V:V) mixture (a4, b4), and DMSO (a5, b5), respectively, for 5 days. The images show that the two nanosheets do not stack with each other, but rather form a three-dimensional flower shape. Both nanosheets can be stably stored in methanol, a methanol / acetic acid (9:1, V:V) mixture, and DMSO. However, high concentrations of acetic acid can destroy the organic framework of the MOFs material.

[0053] Figure 2 The SEM images of D-PABA nanosheets prepared in Example 1 (a1 and a2), and the SEM images of D-MIPs prepared at different photoinitiated polymerization times of 4.0h (b1 and b2), 8.0h (c1 and c2) and 12h (d1 and d2). Figure 2 As can be seen from a1 and a2 of D-PABA, the surface of the D-PABA is relatively smooth. As the illumination time increases, the surface of the generated imprinted polymer nanosheets becomes increasingly rough. Figure 2 b1 to d1, and b2 to d2), the surface has more polymer particles after 12 h of photopolymerization, and the thickness of the nanosheets increases significantly.

[0054] Figure 3 The water contact angles of Zr-BTB-FA (a), D-PABA (b), and D-MIPs (c) prepared in Example 1 are shown in the figure. As can be seen in the figure, the water contact angle of the Zr-BTB-FA nanosheets is 32°, the water contact angle of the double-bond-modified D-PABA is 57°, and the water contact angle of the D-MIPs modified with the imprinted polymer is reduced to 25°. This is mainly because the double-bond modification leads to an increase in the water contact angle of D-PABA, while the use of the hydrophilic functional monomer AcrU and the crosslinker MBAA in the imprinting process leads to a decrease in the water contact angle of D-MIPs. Their hydrophilic surface properties are more conducive to the dispersion of the adsorbent in aqueous solution and the rapid mass transfer of water-soluble target molecules.

[0055] Figure 4 The XRD spectra of Zr-BTB-FA, D-PABA, and D-MIPs prepared in Example 1 are shown. As can be seen from the figure, all three materials have MOFs nanosheet structures, and the crystal structure maintains good stability throughout the functionalization and imprinting process.

[0056] Figure 5The BET analysis of D-PABA (a) and D-MIPs (b) prepared in Example 1. The figure shows that D-PABA and D-MIPs have mesoporous structures with pore diameters of 8.49 nm and 7.05 nm, respectively, and specific surface areas S BET 282.52m respectively 2 / g and 88.33m 2 / g, the specific surface area of ​​D-PABA to D-MIPs decreased significantly; the pore volume of D-PABA decreased from 0.090 cm 3 / g is reduced to 0.019cm / g for D-MIPs 3 / g, which also indirectly proves the successful grafting of MIPs on the surface of D-PABA.

[0057] Example 2:

[0058] (1) Preparation of Zr-BTB-PABA:

[0059] A mixture of 12.5 mg of ZrCl₄ and 10 mg of H₃BTB was dissolved in 3.75 mL of DMF. The mixture was sonicated for 10 minutes, followed by the addition of 0.875 mL of formic acid and 56.25 μL of deionized water. After sonication, the mixture was hydrothermally reacted in a reactor at 110°C for 36 hours. After cooling to room temperature, the solid was centrifuged to obtain a white solid. The solid was washed three times with DMF and ethanol, and then dried in vacuo at 45°C to obtain zirconium MOF nanosheets with carboxyl groups (Zr-BTB-FA).

[0060] Subsequently, 100 mg of Zr-BTB-FA nanosheets were dispersed in 25 mL of DMF (DMF1). 950 mg of PABA was then added to 15 mL of DMF (DMF2) and sonicated to dissolve. The mixture was then added to the Zr-BTB-FA dispersion and mixed. The mixture was refluxed at 140°C for 60 hours, cooled to room temperature, and the pale yellow product was collected by centrifugation. The product was washed three times with DMF and ethanol, and dried in vacuo at 45°C to obtain the amino-bearing zirconium MOF nanosheets (Zr-BTB-PABA).

[0061] (2) Preparation of D-MIPs:

[0062] 0.1 g of Zr-BTB-PABA nanosheets were dispersed in 45 mL of dichloromethane, and 3.6 mL of methacrylic anhydride and 0.27 mL of triethylamine were added. The mixture was heated at 50 °C for 12 h under condensation reflux. After the reaction was completed, the mixture was cooled to room temperature, the product was collected by centrifugation, washed three times with dichloromethane, and dried in vacuo at 45 °C to obtain D-PABA nanosheets.

[0063] (3) Preparation of D-MIPs:

[0064] First, 0.1 mmol of the template molecule AMP was dissolved in 18 mL of Tris-HCl buffer solution (pH = 7.4, 50 mM), 0.1 mmol of AcrU was added, and nitrogen was passed through the solution to remove oxygen at room temperature. The first pre-assembly was performed based on base complementary pairing in a dark environment for 12 h. Subsequently, 15 mg of D-PABA nanosheets were preassembled for a second time under stirring at room temperature, deoxygenated with nitrogen (N2), and light-shielded conditions for 12 hours based on metal ion coordination. 0.100 g of the crosslinker N,N'-methylenebisacrylamide (MBAA) was then added, and nitrogen was then removed. 0.008 g of the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone was added, and nitrogen was removed. Photopolymerization was initiated at 25°C using a UV lamp (UV wavelength λ = 254 nm) for 8 hours. The resulting D-MIPs were then collected by centrifugation. The D-MIPs were then eluted with a methanol / acetic acid (9:1, v:v) mixture to remove unreacted template molecules and organic solvent until no AMP molecules were detected in the eluate. Finally, the resulting D-MIPs were dried in vacuo at 45°C.

[0065] At the same time, referring to the above method, but without adding the template molecule AMP before photoinitiated polymerization, hydrophilic MOFs surface non-imprinted nanosheet adsorbents (D-NIPs) were prepared as a reference for adsorption performance research.

[0066] Example 3:

[0067] (1) Preparation of Zr-BTB-PABA:

[0068] A mixture of 12.5 mg of ZrCl₄ and 11.25 mg of H₃BTB was dissolved in 6.25 mL of DMF. The mixture was sonicated for 10 minutes, followed by the addition of 1.0 mL of formic acid and 62.5 μL of deionized water. After sonication, the mixture was hydrothermally reacted in a reactor at 130°C for 60 hours. After cooling to room temperature, the solid was centrifuged to obtain a white solid. The solid was washed three times with DMF and ethanol, and then dried in vacuo at 45°C to obtain zirconium MOF nanosheets with carboxyl groups (Zr-BTB-FA).

[0069] Subsequently, 100 mg of Zr-BTB-FA nanosheets were dispersed in 35 mL of DMF (DMF1). 1050 mg of PABA was then added to 25 mL of DMF (DMF2) and ultrasonically dissolved. The mixture was then added to the Zr-BTB-FA dispersion. After reflux at 160°C for 84 hours, the mixture was cooled to room temperature and centrifuged to collect the pale yellow product. The product was washed three times with DMF and ethanol and dried in vacuo at 45°C to obtain amino-bearing zirconium MOF nanosheets (Zr-BTB-PABA).

[0070] (2) Preparation of D-MIPs:

[0071] 0.1 g of Zr-BTB-PABA nanosheets were dispersed in 55 mL of dichloromethane, and 3.7 mL of methacrylic anhydride and 0.28 mL of triethylamine were added. The mixture was heated at 60 °C for 36 h under condensation reflux. After the reaction, the mixture was cooled to room temperature, the product was collected by centrifugation, washed three times with dichloromethane, and dried in vacuo at 45 °C to obtain D-PABA nanosheets.

[0072] (3) Preparation of D-MIPs:

[0073] First, 0.1 mmol of the template molecule AMP was dissolved in 22 mL of Tris-HCl buffer solution (pH = 7.4, 50 mM), 0.2 mmol of AcrU was added, and nitrogen was passed through the solution to remove oxygen at room temperature. The first pre-assembly was performed based on base complementary pairing in a dark environment for 12 h. Subsequently, 25 mg of D-PABA nanosheets were deoxygenated by nitrogen flow at room temperature. A second preassembly was performed for 12 hours under stirring in the dark, based on metal ion coordination. 0.150 g of the crosslinker N,N'-methylenebisacrylamide (MBAA) was then added, and oxygen was removed by nitrogen flow. 0.010 g of the photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone was added, and nitrogen flow was removed. Photopolymerization was initiated by UV irradiation at 40°C for 12 hours (UV wavelength λ = 254 nm). The resulting D-MIPs were collected by centrifugation. The D-MIPs were then eluted with a methanol / acetic acid (9:1, v:v) mixture to remove unreacted template molecules and organic solvent until no AMP molecules were detected in the eluate. Finally, the resulting D-MIPs were dried in vacuo at 45°C.

[0074] At the same time, referring to the above method, but without adding the template molecule AMP before photoinitiated polymerization, hydrophilic MOFs surface non-imprinted nanosheet adsorbents (D-NIPs) were prepared as a reference for adsorption performance research.

[0075] Test Example 1:

[0076] 2.0 mL of adenosine monophosphate (AMP) solution with an initial concentration of 300 μmol / L was added to a centrifuge tube (the solvent was a Tris-HCl buffer solution with a pH of 7.4 and 50 mM), and six D-MIPs and D-NIPs adsorbents with a mass ratio of AMP to AcrU of 1.0:1.0, 1.0:1.5, and 1.0:2.0 and a photopolymerization time of 4.0, 8.0, and 12 h were added, respectively. The adsorption was carried out in a constant temperature water bath at 298 K. After the adsorption was completed, it was filtered with a microporous nitrocellulose membrane (pore size of 0.22 μm). The AMP concentration in the filtrate was determined by UV-vis detection at a wavelength of 259 nm, and the results were obtained. Figure 6The results showed that when the molar ratio was 1.0:1.5 and the photopolymerization time was 4.0 hours, the imprinting factor was 2.524 and the maximum adsorption capacity was 202.42 μmol / g. This may be because the photopolymerization time was too long or the functional monomers were too much, resulting in an overly thick imprinted polymer layer, which trapped the recognition sites and made them difficult to elute. The reduction in effective recognition sites led to a decrease in adsorption capacity and a negative impact on mass transfer efficiency. When the photopolymerization time was too short or the monomer content was too low, the imprinted layer was too thin, and the reduction in recognition sites further reduced the adsorption capacity. In summary, the optimal polymerization time was 4.0 hours, and the optimal ratio of template molecule to functional monomer was 1.0:1.5.

[0077] Test Example 2:

[0078] A series of 2.0 mL of AMP solution with an initial concentration of 300 μmol / L was transferred to a centrifuge tube (the solvent was a Tris-HCl buffer solution with a pH of 7.4 and 50 mM), and 2.0 mg of D-MIPs, D-NIPs, and D-PABA were added as adsorbents, respectively. Static adsorption was performed under water bath shaking conditions. The solution was filtered with a microporous nitrocellulose membrane (pore size of 0.22 μm) at time points of 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, 12, 24, and 48 h, respectively. The AMP concentration in the filtrate was measured by UV-vis at a wavelength of 259 nm, and the results were obtained. Figure 7 The results showed that the adsorption capacities of D-MIPs, D-NIPs, and D-PABA increased rapidly within the first 2.0 hours, indicating that the template molecules could easily diffuse into the adsorbent. Furthermore, the adsorption capacity of D-MIPs for AMP was greater than that of D-NIPs and D-PABA, indicating that there were more imprinted recognition sites on the D-MIPs surface.

[0079] Test Example 3:

[0080] 2.0 mL of AMP solutions with initial concentrations of 30, 60, 100, 150, 300, 500, 700, and 1000 μmol / L were added to centrifuge tubes (the solvent was a Tris-HCl buffer solution with a pH of 7.4 and 50 mM), and 2.0 mg of three adsorbents, D-MIPs, D-NIPs, and D-PABA, were added respectively. The test solutions were placed in a water bath at 288K, 298K, and 308K for static adsorption for 12 h, and then filtered with a microporous nitrocellulose membrane (pore size of 0.22 μm). The AMP concentration in the filtrate was detected by UV-vis at a wavelength of 259 nm, and the results were obtained. Figure 8 ; The results show that the maximum adsorption capacity of D-MIPs Q mThe adsorption capacity of ZrO2 was 286.7 μmol / g, which was higher than that of D-NIPs (97.57 μmol / g) and single receptor imprinted adsorbent D-PABA (85.67 μmol / g), proving that the dual receptors formed by the complementary base pairing of pyrimidine functional groups and the coordination of metal ions play an important role in enhancing the adsorption capacity. 4+ , which has a metal coordination effect on AMP, resulting in a larger adsorption capacity. D-NIPs, which possess both metal ions and functional monomers, have slightly higher adsorption capacities than D-PABA, but their adsorption capacity is significantly reduced compared to the dual receptor imprinting recognition sites of D-MIPs. Furthermore, adsorption capacity increases significantly with increasing water bath temperature, likely because higher temperatures enhance the diffusion rate of AMP molecules in solution. Therefore, solution temperature plays a crucial role in enhancing AMP adsorption performance.

[0081] Test Example 4:

[0082] dG, dC, dA, ADP, and ATP were selected as reference molecules, and a solution with a concentration of 700 μmol / L was prepared (the solvent was a Tris-HCl buffer solution with a pH of 7.4 and 50 mM). 2.0 mL was transferred to a centrifuge tube, and 2.0 mg of D-MIPs and D-NIPs were added as adsorbents. After static adsorption for 12 hours under shaking conditions in a water bath, the adsorbents were filtered using a microporous nitrocellulose membrane (pore size of 0.22 μm). The unadsorbed molecules were detected by UV-vis at wavelengths of 252 nm (dG), 270 nm (dC), 259 nm (dA), 259 nm (ADP), and 259 nm (ATP), and the results were used to conclude. Figure 9 The adsorption capacity of AMP was the highest (243.44 μmol / g), significantly higher than that of ATP (103.07 μmol / g), dC (40.15 μmol / g), dG (29.06 μmol / g), ADP (99.55 μmol / g), and dA (77.65 μmol / g), while the results of D-NIPs were very different, indicating that the combination of physical shape memory and chemical recognition of the imprinted recognition site plays a dominant role in the selective separation of the target molecule AMP.

Claims

1. A method for preparing a hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent, characterized in that: The steps include: (1) Preparation of Zr-BTB-PABA: A mixture of zirconium chloride ZrCl4 and 1,3,5-tris(4-carboxyphenyl)benzene H3BTB was dissolved in N,N-dimethylformamide (DMF), and formic acid and deionized water were added after ultrasonication. The ultrasonic mixing was continued to obtain a mixed solution A, and then the mixed solution A was placed in a reactor for hydrothermal reaction. After cooling to room temperature, the solid was centrifuged to obtain a white solid, which was washed several times with DMF and ethanol and dried in vacuo to obtain zirconium MOF nanosheets with carboxyl groups, namely Zr-BTB-FA. Subsequently, Zr-BTB-FA nanosheets were dispersed in DMF, and 4-aminobenzoic acid PABA was added to DMF and ultrasonically dissolved. The PABA solution was added to the Zr-BTB-FA dispersion to obtain a mixed solution B. The mixed solution B was heated, condensed, and refluxed for reaction, then cooled to room temperature. The light yellow product was collected by centrifugation, washed several times with DMF and ethanol, and vacuum dried to obtain zirconium MOFs nanosheets with amino groups, namely Zr-BTB-PABA. (2) Preparation of D-PABA: Zr-BTB-PABA nanosheets were dispersed in dichloromethane, and methacrylic anhydride and triethylamine were added to obtain a mixed solution C. The mixed solution C was heated and condensed under reflux. After the reaction was completed, the mixture was cooled to room temperature, and the product was collected by centrifugation, washed several times with dichloromethane, and vacuum dried to obtain D-PABA nanosheets. (3) Preparation of D-MIPs: First, the template molecule AMP was dissolved in a Tris-HCl buffer solution, and the functional monomer 5-(2-methoxyvinyl)-2′-deoxyuridine (AcrU) was added. N2 was passed through the solution at room temperature to remove oxygen, and the first pre-assembly was performed based on base complementary pairing in a light-proof environment. Subsequently, D-PABA nanosheets were added, and N2 was passed through the reaction mixture to remove oxygen at room temperature. A second pre-assembly was performed based on metal ion coordination under stirring in the dark. The cross-linker N,N'-methylenebisacrylamide MBAA was then added, and N2 was continued to be passed through the reaction mixture to remove oxygen. The photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone was added, and N2 was continued to be passed through the reaction mixture to remove oxygen. After photopolymerization was initiated by UV irradiation, the product D-MIPs was collected by centrifugation. The D-MIPs were then eluted with a mixed solution of methanol / acetic acid as an eluent to remove unreacted template molecules and organic solvents until no adenosine monophosphate (AMP) molecules were detected in the eluent. Finally, the product D-MIPs were dried under vacuum conditions.

2. The preparation method according to claim 1, wherein In the mixed solution A of step (1), the dosage ratio of ZrCl4, H3BTB, DMF, formic acid and deionized water is 1.0 mg: (0.8-0.9) mg: (0.3-0.5) mL: (0.07-0.08) mL: (4.5-5.0) μL.

3. The preparation method according to claim 1, wherein In step (1), the temperature of the hydrothermal reaction is 110° C.-130° C., and the hydrothermal reaction time is 36-60 h.

4. The preparation method according to claim 1, wherein In the mixed solution B of step (1), the mass ratio of Zr-BTB-FA to PABA is 1.0 mg:(9.5-10.5) mg. In the mixed solution, the concentration of Zr-BTB-FA is 1.67-2.5 mg / mL, and the concentration of PABA is 16.67-25 mg / mL.

5. The preparation method according to claim 1, wherein In step (1), the temperature of the condensation reflux reaction is 140° C.-160° C., and the time is 60 h-84 h.

6. The preparation method according to claim 1, wherein In the mixed solution C of step (2), the amount ratio of the Zr-BTB-PABA, dichloromethane, methacrylic anhydride and triethylamine is 1.0 g: (450-550) mL: (36-37) mL: (2.7-2.8) mL.

7. The preparation method according to claim 1, wherein In step (2), the condensation reflux temperature is 50-60° C., and the time is 12 h-36 h.

8. The preparation method according to claim 1, wherein In step (3), the ratio of AMP, 5-(2-methoxyvinyl)-2′-deoxyuridine AcrU, D-PABA, MBAA and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is 1.0 mmol: (1.0-2.0) mmol: (150-250) mg: (1.0-1.5) g: (0.08-0.10) g; the concentration of AMP in the Tris-HCl buffer solution is 4.55*10 -3 ~5.56*10 -3 mol / L.

9. The preparation method according to claim 1, wherein In step (3), The photopolymerization time is 4.0-12 hours, the reaction temperature is 25-40°C, and the ultraviolet light wavelength λ of the UV lamp is 254nm; The time for the first and second pre-assembly is 12 hours each; Tris-HCl buffer solution has a pH of 7.4 and a concentration of 50 mM; In the methanol / acetic acid mixed solution, the volume ratio of methanol to acetic acid is 9:

1.

10. Use of the hydrophilic dual-receptor MOFs nanosheet surface imprinted adsorbent prepared by the method according to any one of claims 1 to 9 for selective separation of adenosine monophosphate.

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