Surface molecularly imprinted polymer, preparation method thereof and application of surface molecularly imprinted polymer in specnuezhenide extraction

Abstract

The invention relates to the technical field of surface molecularly imprinted polymers, and particularly discloses a surface molecularly imprinted polymer as well as a preparation method and application thereof in extraction of specnuezhenide. According to the polymer, porous attapulgite is used as a carrier, a phenol modification layer is grafted on the surface of the carrier through a silane coupling agent, specnuezhenide is further used as a template molecule, and a rigid and stable thermosetting phenolic resin imprinting layer is constructed on the surface of the carrier in situ through a polymerization reaction of phenol and an aldehyde monomer. The imprinting layer has good chemical stability, effectively overcomes the defect of selectivity reduction caused by easy swelling of a traditional polymer, and can realize high-selectivity rapid adsorption and efficient desorption of specnuezhenide through the interaction of recognition holes completely exposed on the surface of the imprinting layer and directional hydrogen bonds; and the material can be repeatedly used and has stable performance. The invention provides a solution with a good industrialization prospect for efficient, green and high-purity separation of specnuezhenide from a complex plant matrix.

Description

Technical Field

[0001] This invention relates to the field of surface molecular imprinting materials technology, and in particular to a surface molecular imprinting polymer, its preparation method, and its application in the extraction of ligustrazine. Background Technology

[0002] Ligustrum lucidum, a traditional Chinese medicinal herb of the Oleaceae family, is cool in nature and has a sweet and bitter taste. It nourishes the liver and kidneys, strengthens the lower back and knees, and promotes healthy hair and vision. Clinically, it is widely used in the treatment of endocrine and metabolic diseases, cardiovascular diseases, and menopausal syndrome. Modern pharmacological studies have shown that the pharmacological activity of Ligustrum lucidum mainly comes from its various chemical components, including triterpenoids, secoiridoid glycosides, and p-hydroxyphenylethanol glycosides. Among these, secoiridoid glycosides are one of its core active ingredients, exhibiting significant pharmacological activities such as hepatoprotection, choleretic effects, anti-inflammatory and antibacterial properties, hypoglycemia and lipid-lowering effects, enhanced immune regulation, anti-osteoporosis, and anti-tumor effects, showing broad prospects for development and application. Specnuezhenide, in particular, is a secoiridoid glycoside compound with important medicinal value, and its efficient and selective separation and purification is a key step in the development of related pharmaceutical products.

[0003] Existing methods for extracting the effective components of privet fruit generally include solvent extraction and hot reflux extraction. Furthermore, the separation of specific privetin often relies on traditional techniques such as column chromatography and macroporous adsorption resins. These methods generally suffer from drawbacks such as low selectivity, high solvent consumption, and long processing time, which restricts their efficiency and economy in large-scale application.

[0004] Molecular imprinting technology can prepare polymeric materials with predetermined selectivity for specific target molecules, providing a highly promising solution for highly selective separation. In existing technologies, a wide variety of functional polymer matrices are used to construct molecularly imprinted layers, with acrylate and vinyl monomers formed through free radical polymerization being the most widely used. However, these polymers may swell to varying degrees under polar solvent conditions, causing deformation or size changes in the pre-constructed imprinted cavities, thereby reducing their selectivity. Furthermore, this swelling not only disables specific binding sites but also exposes numerous non-specific binding sites, leading to non-specific adsorption of other structurally similar polar impurities in the extract, resulting in low product purity that fails to meet the requirements of high-end applications.

[0005] Therefore, developing a novel molecularly imprinted polymer matrix material that combines high stability and high selectivity is of urgent practical significance and technical value for achieving high-purity and high-efficiency industrial extraction of ligustrazine. Summary of the Invention

[0006] To address the problems of poor selectivity and low purity in the extraction of ligustrum lucidum glycosides using existing surface-imprinted polymers, this invention provides a surface-imprinted polymer, its preparation method, and its application in the extraction of ligustrum lucidum glycosides. This invention constructs a thermosetting phenolic resin imprinted layer on the surface of an attapulgite carrier, combining the advantages of rapid mass transfer and high site accessibility of surface imprinting technology. Furthermore, the stable bonding between the carrier and the resin layer, along with the rigid structure of the resin itself, ensures the structural stability of the material during multiple adsorption-desorption cycles. This provides a novel and reliable separation material for the high-purity, high-efficiency, and large-scale extraction of ligustrum lucidum glycosides.

[0007] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a surface molecularly imprinted polymer, comprising a porous carrier and a thermosetting phenolic resin imprinted layer bound to the surface of the porous carrier by a silane coupling agent; wherein the thermosetting phenolic resin imprinted layer has recognition holes that are complementary to the spatial structure and functional groups of the template molecules. The thermosetting resin is formed by the condensation reaction of phenol and aldehydes.

[0008] Compared to existing technologies, the surface molecularly imprinted polymer provided by this invention uses a thermosetting phenolic resin with good chemical stability and a rigid three-dimensional network structure as the imprinting layer matrix. This fundamentally overcomes the defects of traditional acrylic polymers, such as easy swelling in solvents leading to deformation of imprinted cavities and decreased selectivity. It ensures high selective adsorption of target molecules throughout the extraction process, effectively avoiding interference from structural analogs and other coexisting impurities in the crude extract. Simultaneously, the condensation reaction of phenol and aldehyde monomers is easier to control, facilitating the formation of stable recognition cavities that are more precisely complementary to the target molecules in terms of spatial size and functional groups. This achieves high selective recognition and adsorption of target molecules in complex plant extracts. After adsorption, efficient desorption and recovery of target molecules can be achieved through a simple desorption process. Furthermore, the surface molecularly imprinted polymer can be repeatedly regenerated and reused, improving the recovery rate of target molecules while reducing resource waste and environmental pollution, thus meeting the development needs of green extraction.

[0009] Furthermore, the porous carrier is an attapulgite.

[0010] Furthermore, the template molecule is ligustrazine.

[0011] In thermosetting phenolic resin imprinted layers, phenolic hydroxyl groups can be precisely identified with specific ligustrazine through directional hydrogen bonding. Combined with precisely complementary spatial vacancies, highly selective adsorption of specific ligustrazine can be achieved, significantly improving the recovery rate and purity of specific ligustrazine.

[0012] Secondly, the present invention also provides a method for preparing the above-mentioned surface molecularly imprinted polymer, comprising at least the following steps: S1, the porous support is dispersed in an organic solvent, a silane coupling agent is added to carry out a silanization reaction, after the reaction is completed, phenol is added, and the temperature is raised to carry out a modification reaction to obtain a modified porous support; S2, the modified porous carrier, template molecule, aldehyde, initiator and crosslinking agent are polymerized in an organic solvent. After the reaction is completed, the template molecule is eluted to obtain a surface molecularly imprinted polymer.

[0013] This invention first utilizes a silane coupling agent to surface-silanize a porous support, and then further modifies it by grafting phenol, achieving stable anchoring of the imprinted layer precursor on the support surface. This ensures stable chemical bonding between the subsequent imprinted layer and the support, effectively preventing peeling or detachment of the imprinted layer during use. Then, in step S2, the modified porous support, template molecules, aldehydes, initiators, and crosslinking agents are placed in the same system for polymerization. After the polymerization reaction is complete, the template molecules are eluted to remove them, forming stable recognition sites within the phenolic resin imprinted layer that highly match the target molecules in size, shape, and functional group orientation. The entire process is mild, simple, and highly reproducible, providing a reliable method for the controllable preparation and large-scale production of high-performance surface molecular imprinted polymers.

[0014] Furthermore, in S1, the porous carrier is an attapulgite.

[0015] Specifically, before modification, the attapulgite is ground and passed through a 200-mesh sieve.

[0016] Furthermore, in S1 and S2, the organic solvent is one or both of toluene and xylene.

[0017] Further, in S1, the silane coupling agent is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0018] Furthermore, in S1, the mass-to-volume ratio of the porous support to the organic solvent is 1 g: (2~5) mL.

[0019] Furthermore, in S1, the mass-to-volume ratio of the porous support to the silane coupling agent is (1~2) g:1 mL.

[0020] Furthermore, in S1, the temperature of the silanization reaction is 80℃~110℃, and the reaction time is 6h~12h.

[0021] Furthermore, in S1, the mass ratio of the porous support to phenol is (5~13):1.

[0022] Furthermore, in S1, the temperature of the modification reaction is 80℃~120℃, and the reaction time is 6h~12h.

[0023] Optimal reaction temperature and time can promote stable grafting of phenol onto the surface of the silanized support, thereby improving the interfacial bonding between the subsequent imprinted layer and the support.

[0024] Furthermore, in S2, the template molecule is ligustrazine.

[0025] Further, in S2, the aldehyde is at least one of formaldehyde, furfural, or benzaldehyde.

[0026] Furthermore, in S2, the initiator is benzoyl peroxide.

[0027] Furthermore, in S2, the crosslinking agent is hexamethylenetetramine.

[0028] Furthermore, in S2, the mass-to-volume ratio of the modified porous support to the organic solvent is 1 g: (2~5) mL.

[0029] Furthermore, in S2, the mass ratio of the modified porous support to the template molecule is 1:(0.1~0.5).

[0030] Furthermore, in S2, the molar ratio of the aldehyde to phenol is (2~4):1.

[0031] Furthermore, in S2, the molar ratio of the template molecule to the initiator is 1:(0.2~0.5).

[0032] Furthermore, in S2, the amount of crosslinking agent added is 1% to 10% of the total mass of the modified porous carrier, aldehyde, template molecule and initiator.

[0033] Furthermore, in S2, the specific steps of the polymerization reaction include: first reacting at 60℃~70℃ for 2h~4h, then raising the temperature to 70℃~80℃ for 2h~3h, and finally raising the temperature to 90℃~100℃ for 2h~4h.

[0034] Specifically, after the polymerization reaction in S2 is completed, the reaction solution is subjected to solid-liquid separation. The separated solid is washed sequentially with a mixed solution of toluene, methanol and ethanol, and then dried at 95℃~100℃ to obtain the surface molecularly imprinted polymer.

[0035] Thirdly, the present invention also provides the application of the above-mentioned surface molecularly imprinted polymer in the extraction of ligustrum glycosides.

[0036] Fourthly, the present invention provides an extractant for extracting specific ligustrazine from privet fruit, comprising the aforementioned surface molecularly imprinted polymer.

[0037] This invention provides a solid adsorption separation material with specific molecular recognition function for the separation and purification of ligustrum lucidum glycosides, effectively solving the industry problems of poor selectivity, low purity and complicated process in the extraction of ligustrum lucidum glycosides. It is particularly suitable for the large-scale, industrial high-purity extraction and preparation of ligustrum lucidum glycosides.

[0038] Fifthly, the present invention also provides a method for extracting specific ligustrazine from privet fruit, comprising the following steps: The above-mentioned surface molecularly imprinted polymer or an extractant used to extract specific ligustrum glycosides from privet fruit was added to the privet fruit extract, and the extraction, elution, collection of eluent, concentration, and drying were carried out to obtain specific ligustrum glycosides.

[0039] By directly adding the molecularly imprinted polymer or extractant to the crude extract of *Ligustrum lucidum*, the precisely complementary rigid imprinted vacancies on its surface, as well as the hydrogen bonding between phenolic hydroxyl groups and specific ligustrol, can achieve efficient and specific capture of specific ligustrol, effectively eliminating interference from coexisting impurities and structural analogs. Subsequent simple elution allows for efficient recovery of the adsorbed specific ligustrol, yielding a high-purity eluent. Due to the chemical stability and structural rigidity of the thermosetting phenolic resin matrix, it can be reused after elution, with minimal performance degradation even after multiple uses. This method not only significantly improves the final purity and recovery rate of specific ligustrol but also greatly reduces the consumption of organic solvents. It is simple to operate and low in cost, providing a highly promising industrial solution for the green and large-scale extraction of specific ligustrol.

[0040] Specifically, the mass ratio of the surface molecularly imprinted polymer to the privet extract is 1:(1~5).

[0041] Specifically, the extraction time is 1 hour to 3 hours.

[0042] Specifically, the elution uses a methanol-ethanol mixed solution with a volume ratio of (9~19):1.

[0043] Specifically, the elution time is 0.5h to 1.5h.

[0044] Specifically, the concentration is carried out by rotary evaporation at a temperature of 30°C to 40°C.

[0045] As a specific embodiment of the present invention, the preparation method of the privet fruit extract includes the following steps: The dried privet fruit was crushed and sieved, placed in the extraction solvent and heated for extraction, then filtered to obtain the privet fruit extract.

[0046] Specifically, the sieving process involves passing the material through a 20-mesh sieve.

[0047] Specifically, the extraction solvent is an aqueous ethanol solution with a mass concentration of 50% to 70%.

[0048] Specifically, the mass-to-volume ratio of the privet fruit to the extraction solvent is 1g:(10~30)mL.

[0049] Specifically, the heating extraction temperature is 50℃~60℃, and the extraction time is 1h~3h.

[0050] In summary, this invention provides a surface-imprinted polymer for the specific extraction of ligustrum lucidum glycosides, its preparation method, and its applications. The polymer uses a porous attapulgite as a carrier, grafting a phenol-modified layer onto its surface via a silane coupling agent. Furthermore, using ligustrum lucidum glycosides as a template molecule, a rigid and stable thermosetting phenolic resin imprinted layer is constructed in situ on the carrier surface through the polymerization reaction of phenol and aldehyde monomers. This imprinted layer exhibits good chemical stability, effectively overcoming the defects of traditional polymers that easily swell, leading to decreased selectivity. Through the fully exposed recognition vacancies and directional hydrogen bonding on its surface, highly selective and rapid adsorption and efficient desorption of ligustrum lucidum glycosides can be achieved. Moreover, the material is reusable and exhibits stable performance. This invention provides a solution with promising industrialization prospects for the efficient, green, and high-purity separation of ligustrum lucidum glycosides from complex plant matrices. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0052] To better illustrate the present invention, further examples are provided below.

[0053] Example 1 This invention provides a method for preparing a surface molecularly imprinted polymer, comprising the following steps: S1. Grind 20g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 60mL of toluene and ultrasonically disperse it at 200W for 1h. Add 10mL of γ-aminopropyltrimethoxysilane and heat it under reflux at 80℃ for 8h in a heated magnetic stirrer. Then add 1.88g of phenol and continue the reaction at 80℃ for 6h. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, 10g of the modified attapulgite prepared above and 3.43g of ligustrazine were added to a three-necked flask containing 30mL of toluene. The mixture was ultrasonically dispersed at 200W for 1h. Then, 1.20g of formaldehyde, 0.32g of benzoyl peroxide and 0.75g of hexamethylenetetramine were added sequentially. The mixture was reacted at 65℃ for 2h, then heated to 75℃ for 2h, and finally heated to 95℃ for 2h. After the reaction was completed, the mixture was filtered and washed sequentially with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1). The mixture was dried at 95℃ to obtain the surface molecularly imprinted polymer.

[0054] The surface molecularly imprinted polymer prepared above is used to extract specific ligustrazine from privet fruit, specifically including the following steps: Step a: Crush the dried privet fruit into powder, pass it through a 20-mesh sieve, weigh 20g of the sieved privet fruit, place it in a 200mL ethanol aqueous solution with a mass concentration of 60%, heat it to 50℃ and reflux for 2h, filter it while hot to obtain privet fruit extract. Step b: Weigh 2g of the surface molecularly imprinted polymer prepared above and mix with 20g of privet fruit extract. Shake and adsorb for 2 hours, filter, add a methanol-acetic acid mixture (17:1 volume ratio) to the filter cake for elution, collect the eluent, concentrate the eluent by rotary evaporation at 35℃, and dry to obtain privetin. HPLC analysis showed that the privetin content was 99.99%, and the privetin recovery rate was 97.70%.

[0055] Recovery rate (%) = (Mass of ligustrum glycosides obtained by elution / Mass of ligustrum glycosides in the extract) × 100% To demonstrate the performance stability of the surface molecularly imprinted polymer prepared in this embodiment during repeated use, a cyclic adsorption-desorption experiment was conducted. The specific steps are as follows: Each cycle was conducted under identical conditions. 2 g of the surface-imprinted polymer was added to an ethanol-water solution (60% mass concentration) containing 100 μg / mL of privetin, and the mixture was shaken and adsorbed at 25 °C for 2 h. The adsorption capacity was measured. Elution was then performed using a methanol-acetic acid mixture (17:1 volume ratio). The eluent was collected, concentrated by rotary evaporation at 35 °C, and dried to obtain privetin. The elution recovery was measured, and the elution efficiency was calculated (elution efficiency = elution recovery / adsorption capacity × 100%). After each elution, the surface-imprinted polymer was washed with anhydrous ethanol, dried, and then added to the next cycle.

[0056] After five adsorption-desorption cycles, the adsorption capacity of the surface molecularly imprinted polymer for ligustrazine remained above 95% of the initial value, and the elution efficiency remained above 92% of the initial value. Neither the adsorption capacity nor the elution efficiency showed a significant decrease.

[0057] Example 2 This invention provides a method for preparing a surface molecularly imprinted polymer, comprising the following steps: S1. Grind 20g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 80mL of xylene and ultrasonically disperse it at 300W for 1h. Add 20mL of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and heat it under reflux at 90℃ for 10h in a heated magnetic stirrer. Then add 1.88g of phenol and continue the reaction at 90℃ for 8h. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, 10g of the modified attapulgite prepared above and 2.56g of ligustrazine were added to a three-necked flask containing 20mL of xylene. The mixture was ultrasonically dispersed at 200W for 1h. Then, 4.80g of furfural, 0.63g of benzoyl peroxide and 1.13g of hexamethylenetetramine were added sequentially. The mixture was reacted at 70℃ for 2h, then heated to 80℃ for 2h, and finally heated to 100℃ for 2h. After the reaction was completed, the mixture was filtered and washed sequentially with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1). The mixture was dried at 90℃ to obtain the surface molecularly imprinted polymer.

[0058] The surface molecularly imprinted polymer prepared above is used to extract specific ligustrazine from privet fruit, specifically including the following steps: Step a: Crush the dried privet fruit into powder, pass it through a 20-mesh sieve, weigh 20g of the sieved privet fruit, place it in a 300mL 50% ethanol aqueous solution, heat to 50℃ and reflux for 2h, filter while hot to obtain privet fruit extract. Step b: Weigh 2g of the surface molecularly imprinted polymer prepared above and mix with 50g of privet fruit extract. Shake and adsorb for 2 hours, filter, add a methanol-acetic acid mixture (12:1 volume ratio) to the filter cake for elution, collect the eluent, concentrate the eluent by rotary evaporation at 40℃, and dry to obtain privetin. HPLC analysis showed that the privetin content was 99.99%, and the privetin recovery rate was 95.33%.

[0059] Example 3 This invention provides a method for preparing a surface molecularly imprinted polymer, comprising the following steps: S1. Grind 24g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 50mL of toluene and ultrasonically disperse it at 300W for 1h. Add 20mL of γ-aminopropyltriethoxysilane and heat it under reflux at 110℃ for 6h in a heated magnetic stirrer. Then add 1.88g of phenol and continue the reaction at 110℃ for 6h. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, take 10g of the modified attapulgite prepared above and 4.85g of ligustrazine and add it to a three-necked flask containing 50mL of toluene. Disperse it by ultrasonication at 200W for 1h. Then add 4.24g of benzaldehyde, 0.27g of benzoyl peroxide and 0.72g of hexamethylenetetramine in sequence. React at 60℃ for 4h, then raise the temperature to 70℃ for 3h, and finally raise the temperature to 90℃ for 4h. After the reaction is completed, filter and wash with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1) in sequence. Dry at 95℃ to obtain the surface molecularly imprinted polymer.

[0060] The surface molecularly imprinted polymer prepared above is used to extract specific ligustrazine from privet fruit, specifically including the following steps: Step a: Crush the dried privet fruit into powder, pass it through a 20-mesh sieve, weigh 20g of the sieved privet fruit, place it in a 300mL ethanol aqueous solution with a mass concentration of 60%, heat it to 50℃ and reflux for 2h, filter it while hot to obtain privet fruit extract. Step b: Weigh 2g of the surface molecularly imprinted polymer prepared above and mix with 30g of privet fruit extract. Shake and adsorb for 2 hours, filter, add a methanol-acetic acid mixture (9:1 volume ratio) to the filter cake for elution, collect the eluent, concentrate the eluent by rotary evaporation at 40℃, and dry to obtain privetin. HPLC analysis showed that the privetin content was 99.99%, and the privetin recovery rate was 92.79%.

[0061] Comparative Example 1 This comparative example provides a method for preparing a surface molecularly imprinted polymer, which differs from Example 1 only in that phenol is replaced with p-phenylphenol, and the rest is exactly the same. Specifically, it includes the following steps: S1. Grind 20g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 60mL of toluene and ultrasonically disperse it at 200W for 1h. Add 10mL of γ-aminopropyltrimethoxysilane and heat it under reflux at 80℃ for 8h in a heated magnetic stirrer. Then add 3.40g of p-phenylphenol and continue the reaction at 80℃ for 6h. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, 10g of the modified attapulgite prepared above and 3.43g of ligustrazine were added to a three-necked flask containing 30mL of toluene. The mixture was ultrasonically dispersed at 200W for 1h. Then, 1.20g of formaldehyde, 0.32g of benzoyl peroxide and 0.75g of hexamethylenetetramine were added sequentially. The mixture was reacted at 65℃ for 2h, then heated to 75℃ for 2h, and finally heated to 95℃ for 2h. After the reaction was completed, the mixture was filtered and washed sequentially with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1). The mixture was dried at 95℃ to obtain the surface molecularly imprinted polymer.

[0062] The surface molecularly imprinted polymer prepared above was used to extract ligustrazine from privet fruit. The specific steps and process conditions were exactly the same as in Example 1, and will not be repeated here.

[0063] HPLC analysis showed that the content of ligustrazine extracted was 98.78%, and the recovery rate of ligustrazine was 85.34%.

[0064] Comparative Example 2 This comparative example provides a method for preparing a surface molecularly imprinted polymer, which differs from Example 1 only in that it involves phenol modification, but is otherwise identical, specifically including the following steps: S1. Grind 20g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 60mL of toluene and ultrasonically disperse it at 200W for 1h. Add 10mL of γ-aminopropyltrimethoxysilane and heat it under reflux at 80℃ for 8h in a heat-collecting magnetic stirrer. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, 10g of the modified attapulgite prepared above and 3.43g of ligustrazine were added to a three-necked flask containing 30mL of toluene. The mixture was ultrasonically dispersed at 200W for 1h. Then, 1.20g of formaldehyde, 0.32g of benzoyl peroxide and 0.75g of hexamethylenetetramine were added sequentially. The mixture was reacted at 65℃ for 2h, then heated to 75℃ for 2h, and finally heated to 95℃ for 2h. After the reaction was completed, the mixture was filtered and washed sequentially with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1). The mixture was dried at 95℃ to obtain the surface molecularly imprinted polymer.

[0065] The surface molecularly imprinted polymer prepared above was used to extract ligustrazine from privet fruit. The specific steps and process conditions were exactly the same as in Example 1, and will not be repeated here.

[0066] HPLC analysis showed that the content of ligustrazine extracted was 97.25%, and the recovery rate of ligustrazine was 80.70%.

[0067] Comparative Example 3 This comparative example provides a method for preparing a surface molecularly imprinted polymer, specifically including the following steps: S1. Grind 20g of attapulgite and pass it through a 200-mesh sieve. Place the sieved attapulgite in 60mL of toluene and ultrasonically disperse it at 200W for 1h. Add 10mL of γ-aminopropyltrimethoxysilane and heat it under reflux at 80℃ for 8h in a heat-collecting magnetic stirrer. Filter the mixture, wash it with anhydrous ethanol, and vacuum dry it at 50℃ to obtain the modified attapulgite. S2, 10g of the modified attapulgite prepared above and 3.43g of ligustrazine were added to a three-necked flask containing 30mL of toluene. The mixture was ultrasonically dispersed at 200W for 1h. Then, 1.44g of acrylic acid, 0.16g of azobisisobutyronitrile and 1.98g of ethylene glycol dimethacrylate were added sequentially. The mixture was reacted at 65℃ for 2h, then heated to 75℃ for 2h, and finally heated to 85℃ for 2h. After the reaction was completed, the mixture was filtered and washed sequentially with a mixed solution of toluene, methanol and ethanol (volume ratio 9:1). The mixture was dried at 85℃ to obtain the surface molecularly imprinted polymer.

[0068] The surface molecularly imprinted polymer prepared above was used to extract ligustrazine from privet fruit. The specific steps and process conditions were exactly the same as in Example 1, and will not be repeated here.

[0069] HPLC analysis showed that the content of ligustrum glycoside obtained from the extraction was 98.34%, and the recovery rate of ligustrum glycoside was 82.13%.

[0070] Comparing Example 1 and Comparative Examples 1-3, it is evident that the phenolic condensation system using phenol is the preferred method for preparing highly selective and stable surface molecularly imprinted polymers. p-Phenylenol (Comparative Example 1) suffers from excessive steric hindrance and hydrophobic interactions, which negatively impacts crosslinking regularity and recognition selectivity; relying solely on the aldehyde-amine reaction (Comparative Example 2) results in weak binding forces and poor structural stability due to the lack of phenolic hydroxyl groups and a rigid network. Compared to double bond polymerization (Comparative Example 3), phenolic condensation, with its highly rigid three-dimensional network and abundant phenolic hydroxyl hydrogen bonding, can more stably and specifically recognize and enrich target molecules in complex systems.

[0071] In summary, the surface molecularly imprinted polymer provided by this invention exhibits excellent high selectivity in the extraction of ligustrum lucidum extract of specific ligustrum glycosides. Furthermore, it is recyclable, simple, efficient, environmentally friendly, and easy to industrialize, thus showing promising prospects for widespread application.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A surface molecularly imprinted polymer, characterized in that, It includes a porous carrier and a thermosetting phenolic resin imprinted layer bound to the surface of the porous carrier by a silane coupling agent; the thermosetting phenolic resin imprinted layer has recognition holes that are complementary to the spatial structure and functional groups of the template molecules. The thermosetting resin is formed by the condensation reaction of phenol and aldehydes.

2. The surface molecularly imprinted polymer as described in claim 1, characterized in that, The porous carrier is an attapulgite; and / or The template molecule is ligustrazine.

3. A method for preparing the surface molecularly imprinted polymer according to claim 1 or 2, characterized in that, It should include at least the following steps: S1, the porous support is dispersed in an organic solvent, a silane coupling agent is added to carry out a silanization reaction, after the reaction is completed, phenol is added, and the temperature is raised to carry out a modification reaction to obtain a modified porous support; S2, the modified porous carrier, template molecule, aldehyde, initiator and crosslinking agent are polymerized in an organic solvent. After the reaction is completed, the template molecule is eluted to obtain a surface molecularly imprinted polymer.

4. The method for preparing the surface molecularly imprinted polymer as described in claim 3, characterized in that, In S1 and S2, the organic solvent is one or both of toluene and xylene; and / or In S1, the silane coupling agent is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

5. The method for preparing the surface molecularly imprinted polymer as described in claim 3, characterized in that, In S2, the template molecule is ligustrazine; and / or In S2, the aldehyde is at least one of formaldehyde, furfural, or benzaldehyde; and / or In S2, the initiator is benzoyl peroxide; and / or In S2, the crosslinking agent is hexamethylenetetramine.

6. The method for preparing the surface molecularly imprinted polymer as described in claim 3 or 4, characterized in that, In S1, the mass-to-volume ratio of the porous support to the organic solvent is 1 g: (2~5) mL; and / or In S1, the mass-to-volume ratio of the porous support to the silane coupling agent is (1~2) g:1 mL; and / or In S1, the silanization reaction is carried out at a temperature of 80°C to 110°C for a reaction time of 6 to 12 hours; and / or In S1, the mass ratio of the porous support to phenol is (5~13):1; and / or In S1, the temperature of the modification reaction is 80℃~120℃, and the reaction time is 6h~12h.

7. The method for preparing the surface molecularly imprinted polymer as described in claim 3, characterized in that, In S2, the mass-to-volume ratio of the modified porous support to the organic solvent is 1 g: (2~5) mL; and / or In S2, the mass ratio of the modified porous support to the template molecule is 1:(0.1~0.5); and / or In S2, the molar ratio of the aldehyde to phenol is (2~4):1; and / or In S2, the molar ratio of the template molecule to the initiator is 1:(0.2~0.5); and / or In S2, the amount of crosslinking agent added is 1% to 10% of the total mass of the modified porous support, aldehydes, template molecules, and initiator; and / or In S2, the specific steps of the polymerization reaction include: first reacting at 60℃~70℃ for 2h~4h, then raising the temperature to 70℃~80℃ for 2h~3h, and finally raising the temperature to 90℃~100℃ for 2h~4h.

8. The application of the surface molecularly imprinted polymer according to claim 1 in the extraction of ligustrazine.

9. An extractant for extracting specific ligustrazine from privet fruit, characterized in that, Includes the surface molecularly imprinted polymer as described in claim 2.

10. A method for extracting specific ligustrazine from privet fruit, characterized in that, The process includes the following steps: adding the surface molecularly imprinted polymer of claim 2 or the extractant for extracting specific ligustrum glycosides from privet fruit as described in claim 9 to the privet fruit extract, performing extraction, elution, collecting the eluent, concentrating, drying, and obtaining specific ligustrum glycosides.