Polyurethane-coated diethyl aminoethyl hexanoate sustained-release microspheres as well as preparation method and application thereof

Abstract

The invention discloses polyurethane coated diethyl aminoethyl hexanoate sustained release microspheres and a preparation method and application thereof. The preparation method comprises the following steps: dissolving diethyl aminoethyl hexanoate with ethyl acetate, adding isophorone diisocyanate, and uniformly mixing to obtain an oil phase; mixing an emulsifier and a polyvinyl alcohol aqueous solution to form a water phase; homogenizing and emulsifying the water phase at normal temperature, and dropwise adding the oil phase while homogenizing and emulsifying to prepare a homogenized and emulsified oil-water emulsified stock solution; dropwise adding a triethanolamine aqueous solution into the oil-water emulsified stock solution in a stirring state, and carrying out a curing reaction; and taking out the reaction liquid, centrifuging, removing the supernatant, and cleaning the precipitate to obtain the polyurethane-coated diethyl aminoethyl hexanoate sustained-release microspheres. A water-in-oil emulsion is prepared on the surface of the diethyl aminoethyl hexanoate through an interfacial polymerization method, the dissolvability, stability and absorbability of the diethyl aminoethyl hexanoate are improved, meanwhile, a polyurethane shell material is formed, and the diethyl aminoethyl hexanoate has the characteristics of low-speed, lasting and slow release of content, reduction of environmental toxicity and the like.

Description

Technical Field

[0001] The invention relates to the field of slow-release plant growth regulators, in particular to a polyurethane-coated aminoethyl ester slow-release microsphere, a preparation method and application thereof. Background Art

[0002] Aminoethyl hexanoate (diethylaminoethanol hexanoate, C 12 H 25 NO2) has the advantage of growth regulation and has been widely used throughout the growth period of grain and agricultural crops. What is particularly notable is that it can not only effectively promote plant growth, but also has the ability to regulate crop resistance. This dual function makes it highly favored in the plant kingdom.

[0003] At present, the conventional use of aminoethyl hexanoate is to use it alone or in combination with other drugs. However, aminoethyl hexanoate itself has an irritating odor and has problems such as poor solubility, poor absorption, poor long-term release ability and low biocompatibility, which affect its actual application effect.

[0004] In recent years, researchers have been committed to exploring efficient preparation methods to construct sustained-release microcapsules. Although in-situ polymerization and recondensation methods have made some progress, they are still limited by the selection and application of precursor materials. In this context, interfacial polymerization has emerged with its unique advantages. This method aims to prepare a polyurethane polymer shell material with stable performance through the gradual addition polymerization of the -NCO functional group in isophorone diisocyanate and the abundant -OH groups in triethanolamine.

[0005] In addition, regarding the microcapsule shell material, a key issue is the low solid content, especially in the polyurethane polymers currently produced in China, the solid content of the -NCO functional group is generally less than 16%, and the -NCO value in the closed curing agent needs to be different according to the drug loading requirements. This situation has an important impact on the performance of sustained-release microspheres, otherwise it will affect its release performance.

[0006] Specifically, lower -NCO content in polyurethane microspheres may help reduce the initial release dose and extend the degradation cycle, thereby alleviating the problem caused by too fast sustained release of drug efficacy to a certain extent. However, this may also bring the risk of insufficient drug release and failure to meet the needs of the critical period of crop growth. Therefore, while pursuing the reduction of -NCO content, it is necessary to comprehensively consider its impact on the overall performance of microspheres, including but not limited to release rate, degradation stability and biocompatibility, in order to find the best balance. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a polyurethane-coated ampicillin sustained-release microsphere and a preparation method thereof, so that the solubility, stability and absorbability of ampicillin can be improved, the long-acting release performance of ampicillin can be enhanced, and the efficacy and bioavailability of ampicillin can be improved.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] In one aspect, the present invention provides a method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres, comprising the following steps:

[0010] (1) dissolving ammonium ethyl acetate in ethyl acetate, adding isophorone diisocyanate, and mixing them evenly to form the oil phase;

[0011] (2) mixing an emulsifier and a polyvinyl alcohol aqueous solution to form a water phase;

[0012] (3) homogenizing and emulsifying the aqueous phase at room temperature, and simultaneously adding the oil phase dropwise during the homogenizing and emulsifying process to obtain a homogenized and emulsified oil-water emulsion stock solution;

[0013] (4) adding a triethanolamine aqueous solution dropwise to the oil-water emulsion stock solution under stirring to carry out a curing reaction;

[0014] (5) The reaction liquid is taken out and centrifuged, the supernatant is removed and the precipitate is washed to obtain polyurethane-coated aminoethyl hexanoate sustained-release microspheres.

[0015] In the step (1), the mass ratio of diethylaminoethyl hexanoate to ethyl acetate is 1:5-1:10; the mass ratio of diethylaminoethyl hexanoate to isophorone diisocyanate is 1:1-1:6.

[0016] In the step (2), the added amount of the emulsifier is 1:0.5-1:3 of diethylaminoethyl hexanoate; and the mass percentage concentration of the polyvinyl alcohol aqueous solution is 0.5%.

[0017] In the step (2), the emulsifier is #1601, #1602, water-soluble chitosan, dextran gel, gelatin or Tween 80; and the polyvinyl alcohol is polyvinyl alcohol-124 type.

[0018] In the step (3), the rotation speed of the homogenization emulsification is 4000r / min-14000r / min; preferably 8000r / min-10000r / min, more preferably 10000r / min.

[0019] In the step (3), the oil-water mass ratio of the oil phase to the water phase is 1:0.5-1:3.5.

[0020] In the step (4), the mass percentage concentration of the triethanolamine aqueous solution is 10%; and the reaction takes 3-5 hours.

[0021] On the other hand, the present invention also provides polyurethane-coated aminoethyl hexanoate sustained-release microspheres prepared by the above-mentioned method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres.

[0022] In another aspect, the present invention also provides a use of the polyurethane-coated aminoethyl ester slow-release microspheres as a plant slow-release growth regulator.

[0023] In another aspect, the present invention further provides a use of the above-mentioned polyurethane-coated aminoethyl hexanoate sustained-release microspheres in promoting seed germination.

[0024] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0025] (1) The present invention uses diethylaminoethyl as the original drug, and prepares an oil-in-water emulsion on the surface of diethylaminoethyl by interfacial polymerization. Isophorone diisocyanate is used as the shell material, which is low in price and improves the utilization rate of diethylaminoethyl. The shell material is mainly used as a coating carrier in the design of sustained-release microspheres, which can better disperse the original drug, improve the solubility of the original drug, and enhance the long-acting release performance of the drug, thereby improving the efficacy and bioavailability of diethylaminoethyl. If diethylaminoethyl is used alone or in combination with other drugs, its odor irritation, short efficacy period, and low bioavailability affect its use;

[0026] (2) The present invention uses polyurethane to coat ethylamine, which can obtain microspheres with small particle size (<0.135 μm) and low -NCO (<2.26%) functional group content, thereby improving the stability and sustained release of microspheres and reducing the degree of environmental pollution;

[0027] (3) The prepared polyurethane sustained-release microspheres have a wide range of applications and strong applicability. They have excellent coating properties for the original drug, good release effect and stability, and the microcapsule powder can be stored for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0029] Figure 1 : is the embedding rate diagram of polyurethane and diethylaminoethyl hexanoate, wherein a is the standard curve diagram of diethylaminoethyl hexanoate, and b is the drug loading of polyurethane-coated diethylaminoethyl hexanoate sustained-release microspheres;

[0030] Figure 2 It is the infrared image of isophorone diisocyanate (IPDI), DA-6, emulsifier #1601, and emulsifier gelatin;

[0031] Figure 3It is an optical microscope picture of polyurethane-coated aminoethyl ester sustained-release microspheres, wherein, left: #1601 (repeat 1 in Example 1), middle: #1602 (repeat 1 in Example 3), right: gelatin (repeat 1 in Example 5);

[0032] Figure 4 These are scanning electron microscope images of polyurethane-coated aminoethyl ester sustained-release microspheres prepared with different emulsifiers, a, b: 1um, 2um #1601 emulsifier images (repeat 1 in Example 1); c, d: 1um, 2um #1602 emulsifier images (repeat 1 in Example 3); e, f: 1um, 2um gelatin emulsifier images (repeat 1 in Example 5). DETAILED DESCRIPTION

[0033] The present invention provides a new product form for diethylaminoethyl hexanoate - polyurethane-coated diethylaminoethyl hexanoate sustained-release microspheres, which are prepared by interfacial polymerization and include the following steps:

[0034] (1) Ethyl acetate is used to dissolve ammonium ethyl acetate, and isophorone diisocyanate is added and mixed evenly to form the oil phase. Ethyl acetate is a low boiling point solvent that can dissolve oily ammonium ethyl acetate, and isophorone diisocyanate can improve leveling and increase solubility, and can also be mixed with ethyl acetate to achieve good adhesion; in addition, isophorone diisocyanate is an oxidant, and as an important raw material containing diisocyanate groups, isophorone diisocyanate has high functional group activity. In the synthesis process of the polyurethane shell material, it can react efficiently with the hydroxyl group, thereby giving the coating layer stronger binding ability and stability.

[0035] (2) An emulsifier and a polyvinyl alcohol aqueous solution are mixed to form a water phase, wherein the emulsifier is #1601, #1602, water-soluble chitosan, dextran gel, gelatin or Tween 80; and the polyvinyl alcohol is polyvinyl alcohol-124 type.

[0036] (3) homogenizing and emulsifying the water phase at room temperature, and simultaneously adding the oil phase dropwise during homogenization and emulsification to obtain a homogenized oil-water emulsified stock solution; the speed of homogenization and emulsification is 4000 r / min-14000 r / min; preferably 8000 r / min-10000 r / min; more preferably 10000 r / min. The oil-water mass ratio of the oil phase to the water phase is 1:0.5-1:3.5.

[0037] (4) Adding triethanolamine aqueous solution dropwise to the oil-water emulsion stock solution under stirring to carry out curing reaction; the mass percentage concentration of triethanolamine aqueous solution is 10%; reacting for 3-5 hours. For example, the oil-water emulsion stock solution in step (3) can be transferred to a 250mL conical flask, magnetically stirred at 50°C and 500rpm, and at the same time, a 10% triethanolamine aqueous solution is added dropwise with a separatory funnel, reacting for 4 hours to cure the aminoethyl ester polyurethane microspheres; wherein triethanolamine reacts with isophorone diisocyanate to form a polyurethane polymer, and the reaction mechanism is as follows:

[0038]

[0039] (5) The reaction liquid is taken out and centrifuged, the supernatant is removed and the precipitate is washed to obtain the polyurethane-coated aminoethyl hexanoate sustained-release microspheres. For example, after the reaction in step (4) is completed, the reaction liquid is taken out and centrifuged at 10° C. and 10,000 rpm for 10 min, the supernatant is removed and the precipitate is washed three times with pure water to obtain the polyurethane-coated aminoethyl hexanoate sustained-release microspheres.

[0040] Figure 1 The embedding rate diagram of polyurethane and diethylaminoethyl ester is shown, wherein a is the standard curve diagram of diethylaminoethyl ester, and b is the drug loading of polyurethane-coated diethylaminoethyl ester sustained-release microspheres (the mass ratio of diethylaminoethyl ester DA-6 to isophorone diisocyanate IPDA is 1:1-1:6).

[0041] Figure 2 The infrared images of isophorone diisocyanate (IPDI), DA-6, emulsifier #1601, and emulsifier gelatin are shown.

[0042] The content of -NCO solid content, embedding rate and PDI (particle size distribution index) in the polyurethane-coated aminoethyl hexanoate sustained-release microspheres prepared by the above-mentioned preparation method of the present invention are key indicators, among which:

[0043] The content of -NCO solid content is tested according to the methods in the standards "GB / T12009.4-2016, ASTM D2572-97 (2010), ASTM D2572-19, QB / SJ1003-2017".

[0044]

[0045] 4.2: Constant, numerical value of NCO molar mass, g / mol

[0046] B: The volume of the standard hydrochloric acid solution consumed in the titration blank, mL

[0047] V: The value of the volume of the hydrochloric acid standard titration solution consumed by the titration sample, mL

[0048] N: The value of the concentration of the hydrochloric acid standard titration solution, mol / L

[0049] ω: numerical value of sample mass, g

[0050] The embedding rate was modified according to the method summary in the literature “Preparation of Bluebell Fragrance Microcapsules and Their Application in Laundry Detergents, Preparation of Composite Reticulated Shell Fragrance Microcapsules and Analysis of Sustained Release Performance, Beneficial effects of bio-fabricated seleniumnanoparticles as seed nanopriming agent on seed germination in rice (Oryzasativa L.)”. The method standard was “Put 0.1 g of drug-loaded microspheres (polyurethane-coated aminoethyl ester sustained-release microspheres) in a 5 mL stoppered cuvette, add 1 mL of di-n-butylamine, dilute to 5 mL with ethanol, ultrasonicate for 30 min, cool to room temperature, and measure using an ultraviolet spectrophotometer at a wavelength of 210 nm.

[0051]

[0052] η: embedding rate, %

[0053] m1: The mass of aminoethyl ester calculated by fitting curve, g

[0054] m0: mass of the measured microcapsule slurry, gω%: mass fraction of aminoethyl ester encapsulated by polyurethane, %

[0055] m x : Sample (aminoethyl ester (DA-6), ethyl acetate (EA), isophorone diisocyanate (IPDI), emulsifier (#1601), polyvinyl alcohol-124 (PVA-124), triethanolamine (TEA)) mass, g

[0056] PDI (Particle Size Distribution Index) uses NDJ-5S Pro Viscometer to accurately measure the sustained-release microsphere emulsion, including dispersibility and particle size.

[0057] The specific embodiments are explained below for expanded description.

[0058] Example 1

[0059] Accurately weigh 0.8g of aminoethyl hexanoate, 2.4g of isophorone diisocyanate, and 8.0g of ethyl acetate, respectively, and place them in a small beaker, mix them evenly, and use them as the oil phase; separately take a 50mL conical flask containing 3.2g of #1601 and 32g of 0.5% PVA-124 solution to prepare the water phase, place the water phase in a homogenizer for emulsification at 8000r / min, add the oil phase dropwise, and after homogenization and emulsification for 6min, transfer the emulsion to a 250mL conical flask, stir it magnetically at 50°C and 500rpm, and then drop 100g of 10% triethanolamine aqueous solution to solidify the microspheres for 4h, take out and cool to room temperature, centrifuge at 10000r / min, 10°C, and 10min, remove the supernatant, add deionized water to the precipitate, wash it three times, coat it with film, and freeze-dry it for later use.

[0060] Table 1 below shows the results measured according to the aforementioned method.

[0061] Table 1 Physical parameters of sustained-release microspheres of Example 1

[0062]

[0063] Among them, microsphere 1, microsphere 1', and microsphere 1" represent repeat 1, repeat 2, and repeat 3.

[0064] The embedding efficiency of the microspheres was determined to be 81.81±0.07%, and the PDI was 0.22±0.12. Taking Replication 1 as an example, the obtained emulsion and freeze-dried microspheres were observed using an optical microscope (OM). Figure 3 As shown (left), by comparison, it is found that the molding is better and the coverage is more complete; this shows that the embedding effect is good and suitable for application; scanning electron microscopy (SEM) observation, such as Figure 4 As shown in (a, b), part of the microsphere structure presents an irregular surface, part of it can be seen as a double-layer surface, and the spherical structure is not smooth and easy to cluster, indicating that there is still room for improvement.

[0065] Example 2

[0066] Accurately weigh 1.6g of aminoethyl hexanoate, 1.6g of isophorone diisocyanate, and 8.0g of ethyl acetate, and place them in a small beaker respectively, mix them evenly and use them as the oil phase; separately take a 50mL conical flask containing 3.2g of #1601 and 32g of 0.5% PVA-124 solution to prepare the water phase, place the water phase in a homogenizer for emulsification at 8000r / min, add the oil phase dropwise, and after homogenization and emulsification for 6min, transfer the emulsion to a 250mL conical flask, stir it magnetically at 50°C and 500rpm, and then drop 100g of 10% triethanolamine aqueous solution to solidify the microspheres for 4h, take it out and cool it to room temperature, centrifuge it at 10000r / min, 10°C, and 10min, remove the supernatant, add deionized water to the precipitate, wash it three times, coat it with film, and freeze-dry it for later use.

[0067] Table 2 below shows the results measured according to the aforementioned method.

[0068] Table 2 Physical parameters of sustained-release microspheres of Example 2

[0069]

[0070] Among them, microsphere 1, microsphere 1', and microsphere 1" represent repeat 1, repeat 2, and repeat 3.

[0071] The embedding efficiency of the microspheres was determined to be 89.90±0.25%, and the PDI was 0.14±0.06. The emulsion and freeze-dried microspheres were observed using an optical microscope (OM). Comparison revealed that the microspheres had good molding and more complete coating. Scanning electron microscopy (SEM) revealed that the microsphere structure had an irregular surface, and the structural molding (spherical) and granulation were poor.

[0072] Example 3

[0073] Accurately weigh 1.6g of aminoethyl hexanoate, 1.6g of isophorone diisocyanate, and 8.0g of ethyl acetate, and place them in a small beaker respectively, mix them evenly and use them as the oil phase; separately take a 50mL conical flask containing 3.2g of #1602 and 32g of 0.5% PVA-124 solution to prepare the water phase, place the water phase in a homogenizer for emulsification at 8000r / min, add the oil phase dropwise, and after homogenization and emulsification for 6min, transfer the emulsion to a 250mL conical flask, stir it magnetically at 50°C and 500rpm, and then drop 100g of 10% triethanolamine aqueous solution to solidify the microspheres for 4h, take out and cool to room temperature, centrifuge at 10000r / min, 10°C, and 10min, remove the supernatant, add deionized water to the precipitate, wash it three times, coat it with film, and freeze-dry it for later use.

[0074] Table 3 below shows the results measured according to the aforementioned method.

[0075] Table 3 Physical parameters of sustained-release microspheres of Example 3

[0076]

[0077] Among them, microsphere 1, microsphere 1', and microsphere 1" represent repeat 1, repeat 2, and repeat 3.

[0078] The embedding efficiency of the microspheres was determined to be 91.32±0.35%, and the PDI was 0.07±0.06. Taking Replication 1 as an example, the obtained emulsion and freeze-dried microspheres were observed using an optical microscope (OM). Figure 3 As shown in (middle), by comparison, it is found that the viscosity is larger and the coverage is more complete; this shows that the embedding effect is good and suitable for application; however, scanning electron microscopy (SEM) observation shows that Figure 4 (c, d), the microsphere structure presents an irregular surface, and the structural molding (spherical) and granulation are poor, indicating that there is still room for improvement.

[0079] Example 4

[0080] Accurately weigh 1.6g of aminoethyl ester, 1.6g of isophorone diisocyanate, and 8.0g of ethyl acetate, respectively, and place them in a small beaker, mix them evenly and use them as the oil phase; separately take a 50mL conical flask containing 3.2g of #1601 and 32g of 0.5% PVA-124 solution to prepare the water phase, place the water phase in a homogenizer for emulsification at 10000r / min, add the oil phase dropwise, and after homogenization and emulsification for 6min, transfer the emulsion to a 250mL conical flask, stir it magnetically at 50°C and 500rpm, and then drop 100g of 10% triethanolamine aqueous solution to solidify the microspheres for 4h, take it out and cool it to room temperature, centrifuge it at 10000r / min, 10°C, and 10min, remove the supernatant, add deionized water to the precipitate, wash it three times, coat it with film, and freeze-dry it for later use.

[0081] Table 4 below shows the results measured according to the aforementioned method.

[0082] Table 4 Physical parameters of the sustained-release microspheres of Example 4

[0083]

[0084] Among them, microsphere 1, microsphere 1', and microsphere 1" represent repeat 1, repeat 2, and repeat 3.

[0085] The embedding efficiency of the microspheres was determined to be 89.67±0.56%, and the PDI was 0.14±0.05. The obtained emulsion and freeze-dried microspheres were observed using an optical microscope (OM). By comparison, it was found that the microspheres had good molding and more complete encapsulation.

[0086] Example 5

[0087] Accurately weigh 1.6g of aminoethyl hexanoate, 1.6g of isophorone diisocyanate, and 8.0g of ethyl acetate, and place them in a small beaker respectively, mix them evenly and use them as the oil phase; separately take a 50mL conical flask containing 3.2g of gelatin and 32g of 0.5% PVA-124 solution to prepare the water phase, place the water phase in a homogenizer for emulsification at 10000r / min, add the oil phase dropwise, and after homogenization and emulsification for 6min, transfer the emulsion to a 250mL conical flask, stir it magnetically at 50°C and 500rpm, and then drop 100g of 10% triethanolamine aqueous solution to solidify the microspheres for 4h, take it out and cool it to room temperature, centrifuge it at 10000r / min, 10°C, and 10min, remove the supernatant, add deionized water to the precipitate, wash it three times, coat it with film, and freeze-dry it for later use.

[0088] Table 5 below shows the results measured according to the aforementioned method.

[0089] Table 5 Physical parameters of sustained-release microspheres of Example 5

[0090]

[0091] Among them, microsphere 1, microsphere 1', and microsphere 1" represent repeat 1, repeat 2, and repeat 3.

[0092] The embedding efficiency of the microspheres was determined to be 89.56±0.4%, and the PDI was 0.12±0.07. Taking Replication 1 as an example, the obtained emulsion and freeze-dried microspheres were observed using an optical microscope (OM). Figure 3 As shown in (right), by comparison, it is found that the molding is better and the coating is more complete; scanning electron microscopy (SEM) observation, such as Figure 4 As shown in (e, f), the surface of the microsphere structure is smooth and not easy to cluster, and the overall structural performance is good.

[0093] Example 6 Application study of polyurethane-coated aminoethyl ester sustained-release microspheres (DA-6 microspheres) - promoting seed germination

[0094] The DA-6 microspheres and DA-6 microspheres with the same content of the original drug were compared with the original drug (DA-6) and the control ck (water) to soak the rice seeds and determine the germination rate.

[0095] The measurement results are shown in Table 6 below:

[0096] Table 6 Application research results of sustained-release microspheres

[0097]

[0098] As shown in Table 6, the germination rate of rice seeds soaked with aminoethyl hexachloride (DA-6) microspheres was significantly improved (compared with the control group CK), such as code 2 (Meixiangzhan No. 2, an increase of 0.66%), code 6 (Yliangyou No. 1, an increase of 14.83%), variety 8 (Xiushui 134, an increase of 13.61%), varieties 9, 10, 11 (Fengliangyouxiang No. 1 -0.15%, Yongyou 12 -0.49%, Changbai No. 9 -0.65%), variety 12 (Huazheyou 223, an increase of 8.14%) and variety 13 (Zhuliangyou 835, an increase of 4.78%).

[0099] The DA-6 microspheres all increased compared with CK, such as codes 2, 4, 6, 8, 12, and 13 (Meixiangzhan 2, Yuliangyou 4156, Yliangyou 1, Xiushui 134, Huazheyou 223, and Zhuliangyou 835, respectively). Comparing the DA-6 microspheres with the original drug content and the original drug (DA-6), the DA-6 microspheres had an increased germination rate, indicating that the material had a better germination promotion effect after synthesis than before synthesis, while the original drug content at the same dose decreased.

[0100] In the present invention, polyurethane is innovatively used to encapsulate aminoethyl hexanoate, which changes the traditional single use of aminoethyl hexanoate or the compounding mode with other drugs, and provides a new product form. This design not only successfully retains the original pharmacodynamic stability and other characteristics of aminoethyl hexanoate, but also significantly expands its application range, including enhancing the diverse storage, solubility, absorbability, long-acting release ability and biocompatibility of the product. In addition, the encapsulation method effectively masks the irritating smell of aminoethyl hexanoate, further improving its use experience. Further, by adjusting the drug-shell ratio of sustained-release microspheres, investigating the oil-water ratio, determining the emulsification speed, screening the emulsifier type and finally determining the single factor of the response surface, while pursuing the reduction of -NCO content, the influence on the overall performance of the microspheres is also comprehensively considered, including but not limited to the release rate, degradation stability and biocompatibility, etc., to seek the best balance point.

[0101] The present invention exhibits excellent rapid solubility, long-acting release characteristics and good biocompatibility by using polyurethane coating, and these characteristics work synergistically to greatly improve the long-acting release effect of aminoethyl ester. More importantly, the carbamate group formed by the structure in the form of hydrogen bonds promotes the rapid metabolism of the microspheres in the natural environment, effectively reduces the potential pollution risk of polyurethane materials to the environment, and provides an important idea for realizing the application of green agricultural chemicals.

[0102] Compared with traditional growth regulators characterized by quick-acting and strong volatility, the aminoethyl ester in the present invention uses ethyl acetate as a solvent, which reduces the use of high-risk and high-residual solvents, thereby alleviating soil degradation pressure, reducing harmful emissions during the slow-release degradation process, and providing strong support for environmentally friendly agricultural production. In addition, the polyurethane-coated aminoethyl ester slow-release microspheres are prepared using renewable polymer materials, which not only have high biocompatibility and degradability, but also do not contain any hazardous chemicals, thereby greatly enhancing safety during handling and storage. This design not only meets the demand for sustainable development in modern agriculture, but also provides important guarantees for reducing environmental risks and protecting ecological balance.

[0103] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Those skilled in the art may make some simple modifications, equivalent changes or modifications using the technical contents disclosed above, which all fall within the protection scope of the present invention.

Claims

1. A method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres, characterized in that: The steps include: (1) dissolving ammonium ethyl acetate in ethyl acetate, adding isophorone diisocyanate, and mixing them evenly to form the oil phase; (2) mixing an emulsifier and a polyvinyl alcohol aqueous solution to form a water phase; (3) homogenizing and emulsifying the aqueous phase at room temperature, and simultaneously adding the oil phase dropwise during the homogenizing and emulsifying process to obtain a homogenized and emulsified oil-water emulsion stock solution; (4) adding a triethanolamine aqueous solution dropwise to the oil-water emulsion stock solution under stirring to carry out a curing reaction; (5) The reaction liquid is taken out and centrifuged, the supernatant is removed and the precipitate is washed to obtain polyurethane-coated aminoethyl hexanoate sustained-release microspheres.

2. The method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (1), the mass ratio of diethylaminoethyl hexanoate to ethyl acetate is 1:5-1:10; the mass ratio of diethylaminoethyl hexanoate to isophorone diisocyanate is 1:1-1:

6.

3. The method for preparing the polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (2), the added amount of the emulsifier is 1:0.5-1:3 of diethylaminoethyl hexanoate; and the mass percentage concentration of the polyvinyl alcohol aqueous solution is 0.5%.

4. The method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (2), the emulsifier is #1601, #1602, water-soluble chitosan, dextran gel, gelatin or Tween 80; and the polyvinyl alcohol is polyvinyl alcohol-124 type.

5. The method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (3), the rotation speed of the homogenization emulsification is 4000r / min-14000r / min; preferably 8000r / min-10000r / min, more preferably 10000r / min.

6. The method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (3), the oil-water mass ratio of the oil phase to the water phase is 1:0.5-1:3.

5.

7. The method for preparing polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to claim 1, characterized in that: In the step (4), the mass percentage concentration of the triethanolamine aqueous solution is 10%; and the reaction takes 3-5 hours.

8. A polyurethane-coated aminoethyl ester sustained-release microsphere, characterized in that: The microspheres are prepared by the method for preparing the polyurethane-coated aminoethyl hexanoate sustained-release microspheres according to any one of claims 1 to 7.

9. Use of the polyurethane-coated aminoethyl ester sustained-release microspheres according to claim 8 as a plant slow-release growth regulator.

10. Use of the polyurethane-coated aminoethyl ester sustained-release microspheres according to claim 8 in promoting seed germination.

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