Preparation method of chitosan modified enzyme response type wood preservative

Abstract

The invention belongs to the technical field of preparation methods of preservatives, and discloses a preparation method of a chitosan modified enzyme response type wood preservative, which comprises the following steps: preparing monodisperse silica nanoparticles by a preset method, and preparing a chitosan modified enzyme response type wood preservative on the basis of preparing the monodisperse silica nanoparticles. The preparation method comprises the following steps: synthesizing HMON with a cavity, a preset specific surface area and a controllable mesoporous structure by adopting a preset mode, and violently stirring ultrapure water, absolute ethyl alcohol and a concentrated ammonia solution for a period of time to be fully mixed; the natural antibacterial property of garlic is utilized, growth of microorganisms in wood is effectively inhibited, an HMON carrier in the preservative has a large specific surface area and a controllable mesoporous structure, the loading efficiency and stability of garlic NPs are improved, through modification of chitosan, the preservative is endowed with biodegradability and enzyme responsiveness, pollution to the environment is reduced, and the preservative has the advantages of being environmentally friendly and free of pollution. The preparation method is simple, convenient to operate and easy for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of preservative preparation methods, and particularly relates to a method for preparing a chitosan-modified enzyme-responsive wood preservative. Background Art

[0002] Forests are "reservoirs, money stores, grain stores, and carbon stores." As an important component of forests, wood plays an important role in ecological security and sustainable economic and social development. Wood has been a commonly used building material in the world since ancient times. Due to its unique aesthetic and environmental characteristics, it is also considered to be a green and sustainable environmentally friendly material. However, due to the scarcity of global forest resources and strict timber export policies, it is becoming increasingly difficult to import timber. my country's artificial forest area ranks first in the world. The rational use of artificial forest timber is of great significance to alleviating the shortage of timber resources. Artificial forest timber has poor wood properties and is easily corroded by decay fungi, thereby reducing its service life. After being corroded by decay fungi, the physical and chemical properties of artificial forest timber will decrease, and the hierarchical structure will be severely damaged. In order to minimize the waste of wood and maximize the utilization rate of wood, it is necessary to treat wood with antiseptic treatment. Due to the improvement of public environmental awareness, the use of traditional preservatives containing heavy metal elements is gradually being restricted. Therefore, researchers have focused their attention on natural wood preservatives, especially on the preparation and development of plant-based preservatives.

[0003] The use of preservatives is one of the indispensable factors for achieving wood protection. It can effectively inhibit the growth of decay fungi and extend the service life of wood. Chemical preservatives have potential hazards to the environment and human body. Based on this, botanical preservatives have attracted much attention from scholars because of their environmental protection and antibacterial effects. However, since the antibacterial substances of botanical preservatives are mostly natural active ingredients, they are easy to lose, easy to degrade, have a short efficacy period, are sensitive to the environment, unstable agents, and have high production costs in actual production and application. It is necessary to modify botanical preservatives by using appropriate quality improvement and efficiency enhancement technologies. In addition, with the development of society, the rigid demand for preservatives in the field of wood protection will continue to exist. Direct impregnation of preservatives will lead to waste of preservatives and loss of resources, further limiting the scope of application of preservatives. At present, scholars' attention to wood preservatives is mostly focused on the "direct killing" method. Emulsions, granules and suspensions are used more often. The preparation and application methods of such preservatives are relatively simple, and they can be directly applied by adding them to solvents. However, the existing treatment methods of preservatives (such as vacuum pressure impregnation) and the effects of preservatives (such as direct toxicity preservation) lead to the disadvantages of easy waste, easy loss, and low utilization rate of preservatives. It is important to adopt appropriate treatment methods to achieve efficient utilization of preservatives. With the development of the times and the advancement of science and technology, the research on intelligent responsive nano-drug delivery systems with the goals of ecology, safety, efficiency and greenness has attracted much attention.

[0004] The current wood protection method is mainly to inject environmentally friendly plant-based preservatives into the wood through vacuum pressure impregnation. After the preservative is impregnated into the wood, due to the differences in the existing preservative treatment methods and the mechanism of action of the later preservatives, the plant-based preservatives have the disadvantages of large dosage, short efficacy period, and easy loss, which limits their application in the field of wood protection. Therefore, a preparation method of chitosan-modified enzyme-responsive wood preservative is proposed to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a chitosan-modified enzyme-responsive wood preservative to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing a chitosan-modified enzyme-responsive wood preservative, comprising the following steps:

[0007] S1: preparing monodisperse silica nanoparticles by a preset method, synthesizing HMON with cavities, a preset specific surface area and a controllable mesoporous structure by a preset method on the basis of preparing monodisperse silica nanoparticles, and vigorously stirring ultrapure water, anhydrous ethanol and concentrated ammonia solution for a period of time to fully mix them;

[0008] Add 6.2 mL of TEOS, stir at room temperature for 2 h, centrifuge, take the precipitate, wash it three times with ethanol and ultrapure water, and dissolve the precipitate SiO2 in 70 mL of ultrapure water for later use;

[0009] Weigh 1.90g CTAC and 0.05g TEA and add them to 100mL ultrapure water, stir magnetically to fully dissolve them, continue stirring for 2h, add 35mL of the previously prepared SiO2 solution, stir magnetically for 1.5h, then add 2mL BTES to the above solution at 80℃, stir for 2h, centrifuge for 5min under the same conditions, take the precipitate and wash it with ethanol and ultrapure water twice in sequence, add 0.6M Na2CO3 to the above solution and stir at 80℃ for 2h, wash it with ethanol and ultrapure water at 8000r / min for 3 times to obtain a solid product;

[0010] Finally, the solid product was extracted with a methanol solution dissolved in NaCl and stirred at room temperature overnight to remove the CTAC template. After centrifugation and washing, the product was freeze-dried to obtain HMON nanoparticles.

[0011] S2: Weigh 200.00 mg HMON nanoparticles, dissolve in 60 mL ultrapure water, and after uniform dispersion, add 450 μL APTES reagent, stir at room temperature for 10 h, centrifuge with ultrapure water three times, and freeze-dry to obtain amino-functionalized HMON-NH2;

[0012] S3: Weigh 75.00 g of crushed garlic paste and dissolve it in 250 mL of ultrapure water for 2 h, cook it at a suitable temperature for 10 min, and filter it with gauze to obtain a crude garlic extract. Mix 1 mL of garlic extract, 0.09 g of ethylenediamine, 1.00 g of urea and 9 mL of ultrapure water, and microwave it to obtain brown solid granules of garlic NPs;

[0013] The mesopores on the surface of HMON were blocked by chitosan CS with biodegradable properties, and CS was encapsulated on the surface of HMON by grafting cleavable azo bonds on the surface of microspheres.

[0014] S4: Add the preservative garlic NPs prepared in S3 to ultrapure water, prepare a garlic NPs aqueous solution of preset concentration with ultrapure water, dissolve HMON-NH2 in ultrapure water, disperse evenly, add it to the garlic NPs aqueous solution, stir at room temperature for 12 h, remove the supernatant after centrifugation, and wash with ultrapure water 3 times.

[0015] Freeze drying was performed to obtain hollow mesoporous microspheres HMON-garlic NPs loaded with garlic NPs;

[0016] S5: Weigh 0.30g of azobenzene-3,3'-dicarboxylic acid, add it to PBS solution, disperse it evenly by ultrasonication, stir it magnetically for 2h, add 0.45g of NHs and 0.75g of EDC to the dispersed solution, activate it for 3h, weigh 0.80g of the synthesized HMON-garlic NPs, dissolve it in 150mL of PBS solution, add it to the activated solution after it is completely dissolved, stir it at room temperature for 36h, synthesize HMON-garlic NPs-COOH, centrifuge it, rinse it with ethanol several times, freeze-dry it, and keep it for later use;

[0017] S6: 0.50 g of the synthesized HMON-garlic NPs-COOH was placed in 100 mL PBS to fully dissolve it, 3 mg / mL NHs and 6 mg / mL EDC were added, and the activation treatment was carried out for 1.5 h. 0.16 g CS was weighed and added to 60 mL ultrapure water, and 0.6 mL acetic acid was added to prepare a CS solution. The CS solution was slowly poured into the above activated suspension, stirred at room temperature for 48 h, and the product was washed several times after centrifugation, and then freeze-dried in a freeze dryer to obtain HMON-garlic NPs-CS enzyme-responsive wood preservative.

[0018] Preferably, in S1, the preset method includes Law.

[0019] Preferably, in S1, the centrifugal treatment has a centrifugal rate of 10000 r / min and a centrifugal duration of 5 min.

[0020] Preferably, in S3, the power of the microwave treatment is 500 W and the microwave duration is 5 min.

[0021] Preferably, in S4, the centrifugal treatment is carried out at a centrifugal rate of 8000 r / min and for a centrifugal time of 10 min.

[0022] Preferably, in S5, the amount of the PBS solution added is 150 mL, and the pH of the PBS solution is 5.8.

[0023] Preferably, in S5, the centrifugal treatment has a centrifugal speed of 10000 r / min and a centrifugal duration of 5 min.

[0024] Preferably, in S6, the centrifugal treatment has a centrifugal speed of 10000 r / min and a centrifugal duration of 5 min.

[0025] Preferably, in S1, the added amounts of the ultrapure water, anhydrous ethanol and concentrated ammonia solution are 12 mL, 80 mL and 3.6 mL respectively.

[0026] Preferably, in S1, the preset methods are nucleation, coating, punching and denucleation.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The responsive release of the preservative prepared by the present invention provides a new idea for solving the problems of easy waste of preservatives and easy loss of antibacterial components in the field of wood protection. The preservative has high-efficiency antiseptic performance, utilizes the natural antibacterial performance of garlic, effectively inhibits the growth of microorganisms in wood, and the HMON carrier in the preservative has a large specific surface area and a controllable mesoporous structure, which improves the loading efficiency and stability of garlic NPs. The preservative is endowed with biodegradability and enzyme responsiveness through modification of chitosan, which reduces pollution to the environment. The preparation method is simple, easy to operate, and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the hollow mesoporous silica carrier of the present invention;

[0030] Figure 2Transmission electron microscopy images of HMON-garlic NPS and HMON-garlic NPs-CS samples of the present invention (a) is HMON-garlic NP; (b and c) are schematic diagrams of HMON-garlic NPs-CS at different magnifications;

[0031] Figure 3 The antibacterial effects of HMON-CS and HMON-garlic NPs-CS samples of the present invention are shown in (a) HMON-CS; (b) schematic diagram of HMON-garlic NPs-CS;

[0032] Figure 4 This is a photo of the growth of Coriolus versicolor after adding HMON-garlic NPs-GS in the present invention at 6 days:

[0033] Figure 5 Schematic diagram of drug loading and loss rate of garlic NPs and HMON-garlic NPs-GS of the present invention;

[0034] Figure 6 This is a schematic diagram of the weight loss results of wood in the empty group and the treated group after 12 weeks in the examples of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1-Figure 6 As shown, the present invention provides the following technical solutions:

[0037] The preparation of enzyme-responsive wood preservatives mainly includes the following processes: synthesis of carriers, preparation of preservatives, and design of response methods.

[0038] Synthesis of carrier: In the preparation of monodisperse silica nanoparticles ( Based on the method, HMON with cavities, preset specific surface area and controllable mesoporous structure was synthesized by nucleation, coating, drilling and denucleation. 12mL ultrapure water, 80mL anhydrous ethanol and 3.6mL concentrated ammonia solution were measured and stirred vigorously for a period of time to fully mix. 6.2mL LTEOS was added, stirred at room temperature for 2h, centrifuged (10000r / min) for 5min, and the precipitate was washed with ethanol and ultrapure water for 3 times by centrifugation. The precipitate SiO2 was dissolved in 70mL ultrapure water for use. 1.90g CTAC and 0.05g TEA were weighed and added to 100mL ultrapure water, magnetically stirred to fully dissolve, and continued to stir for 2h; 35mL of the previously prepared SiO2 solution was added and magnetically stirred for 1.5h. Then, 2mL BTES was added to the above solution at 80℃, stirred for 2h, centrifuged for 5min under the same conditions, and the precipitate was washed twice with ethanol and ultrapure water. 0.6M Na2CO3 was added to the above solution and stirred at 80°C for 2h, and then washed three times by centrifugation with ethanol and ultrapure water at 8000r / min. Finally, the solid product was extracted with a methanol solution dissolved in NaCl and stirred at room temperature overnight to remove the CTAC template. After centrifugal washing, the product was freeze-dried to obtain HMON nanoparticles.

[0039] Then, 200.00 mg of HMON nanoparticles were weighed and dissolved in 60 mL of ultrapure water. After uniform dispersion, 450 μL of APTES reagent was added, stirred at room temperature for 10 h, centrifuged three times with ultrapure water, and freeze-dried to obtain amino-functionalized HMON-NH2).

[0040] The preservative was then prepared by weighing 75.00 g of crushed garlic paste and dissolving it in 250 mL of ultrapure water for 2 h, boiling it at a suitable temperature for 10 min, and filtering it with gauze to obtain a crude garlic extract. 1 mL of garlic extract, 0.09 g of ethylenediamine (C2H8N2), 1.00 g of urea and 9 mL of ultrapure water were mixed and microwaved (power: 500 W, time: 5 min) to obtain brown solid particles (garlic NPs).

[0041] Design of response mode: An enzyme-responsive preservative was developed based on HMON. Chitosan (CS) with biodegradable properties was used to block the mesopores on the surface of HMON. CS was encapsulated on the surface of HMON by grafting cleavable azo bonds on the surface of microspheres.

[0042] Then, the preservative garlic NPs prepared in the above steps were added to ultrapure water, and a certain concentration of garlic NPs aqueous solution was prepared with ultrapure water. HMON-NH2 was dissolved in ultrapure water, dispersed evenly, added to the garlic NPs aqueous solution, stirred at room temperature for 12 h, centrifuged (8000 r / min) for 10 min, the supernatant was removed, washed with ultrapure water 3 times, and freeze-dried to obtain hollow mesoporous microspheres loaded with garlic NPs (HMON-garlic NPs).

[0043] Weigh 0.30g of azobenzene-3,3'-dicarboxylic acid and add it to 150mL of PBS solution with pH = 5.8. After ultrasonic dispersion, stir magnetically for 2h. Add 0.45g of NHs and 0.75g of EDC to the dispersed solution and activate it for 3h. Weigh 0.80g of the synthesized HMON-garlic NPs and dissolve it in 150mL of PBS solution. After complete dissolution, add it to the activated solution and stir at room temperature for 36h to synthesize HMON-garlic NPs-COOH. Centrifuge (10000r / min) for 5min, rinse with ethanol several times, freeze-dry, and save for later use.

[0044] Then 0.50g of the synthesized HMON-garlic NPs-COOH was placed in 100mL PBS to fully dissolve it, and 3mg / mL NHs and 6mg / mL EDC were added for activation treatment for 1.5h. 0.16g CS was weighed and added to 60mL ultrapure water, and 0.6mL acetic acid was added to prepare CS solution. The CS solution was slowly poured into the above activated suspension, stirred at room temperature for 48h, centrifuged (10000r / min) for 5min, and the product was washed several times and freeze-dried in a freeze dryer to obtain HMON-garlic NPs-CS enzyme-responsive wood preservative.

[0045] Moreover, in the present invention, the responsive release of preservatives provides a new approach to solving the problems faced by the field of wood protection, such as the easy waste of preservatives and the easy loss of antibacterial ingredients. The selection of carrier materials and the construction technology of the response system are closely related to the release performance of preservatives. In order to further meet the sustainable development needs of modern forestry development, from the perspective of the forestry economy, the environmentally sensitive preservative response system has important practical value and cutting-edge research value. Drawing on the modification method, releasing preservatives under environmental stimulation conditions (enzyme response) has practical significance for the intelligent development and application of the field of wood protection.

[0046] Based on the above background, the synthesized hollow mesoporous silica microspheres were used as preservative carriers, preservative garlic NPs as guest molecules, and chitosan (CS) as gating molecules to encapsulate HMON microspheres loaded with garlic NPs. When decay fungi grow and develop, they release highly active laccases, so laccase-responsive wood preservatives were designed to achieve responsive release of preservatives. The synthesized hollow mesoporous silica has a large cavity, such as Figure 1 As shown, a large amount of preservatives can be loaded.

[0047] Furthermore, in the present invention, in order to visually show whether the preservative garlic NPs enter the hollow microspheres and whether the response system is successfully loaded with drugs, the HMON-garlic NPs and HMON-garlic NPs-CS samples were characterized by TEM. Figure 2 As shown. Figure 2 The structure of HMON-garlic NPs can be clearly observed. Figure 1 By comparison, it can be found that the internal cavity of the hollow mesoporous microspheres changes from white to black, which indicates that the preservative garlic NPs fill the cavity inside the microspheres and are evenly distributed. Figure 2 In (a), the edge outline of the microspheres can be clearly seen, the spherical structure is intact, and the garlic NPs are encapsulated by the outline of HMON. Figure 2 (b) and Figure 2 (c) is the TEM image of the response system HMON-garlic NPs-CS synthesized at different magnifications. TEM shows that the inside of the microsphere is black, indicating that the grafting modification at different synthesis stages does not lead to a large loss of garlic NPs from the inside of the HMON microsphere. In addition, it can be found that when garlic NPs are loaded on the microspheres, then grafted and coated with CS, the outer surface of the microspheres becomes irregular. TEM shows that there is a film-like white flocculent substance wrapped around the outer surface of the microspheres, which is attributed to the grafting of azo bonds and the coating of CS. Figure 2 It can be seen that the enzyme-responsive preservative HMON-garlic NPs-CS was successfully synthesized, and the CS coated on the outer surface of the microspheres can block the pores of HMON to prevent the premature leakage of the preservative garlic NPs.

[0048] In addition, before the enzyme-responsive preservative in vitro antibacterial test, the results of HMON-CS without preservative encapsulation and HMON-garlic NPs-CS encapsulated with preservative in PDA culture medium were compared. Figure 3 shown. Figure 3(a) The left picture is a TEM image of HMON-CS, from which the hollow structure inside the microspheres can be seen, and the right picture shows the corresponding antifungal results. After inoculating Coriolus versicolor onto the drug-loaded culture medium, it was found that the hyphae had completely covered the surface of the culture medium after a period of culture, and Coriolus versicolor grew vigorously, indicating that HMON-CS without the preservative garlic NPs had almost no inhibitory effect. Figure 3 (b) It is observed that there is already a distribution of garlic NPs in HMON-garlic NPs-CS, in which the hollow cavity has been occupied; the right figure shows the corresponding antibacterial results, which are consistent with Figure 3 (a) By comparison, it can be found that the diameter of the fungus ring of Coriolus versicolor is smaller, the growth of hyphae is inhibited, and the growth rate is lower, indicating that the enzyme-responsive preservative HMON-garlic NPs-CS formed by filling garlic NPs into the microspheres can release garlic NPs, thereby making the enzyme-responsive preservative HMON-garlic NPs-CS have an antifungal effect.

[0049] Figure 4 The growth photos of Coriolus versicolor at 6 days after adding different concentrations of HMON-garlic NPs-CS to PDA medium are shown. From the photos, it can be seen that the diameter of the fungus ring of Coriolus versicolor is negatively correlated with the concentration of HMON-garlic NPs-CS, that is, the diameter of the fungus ring gradually decreases with the increase of concentration, indicating that the preservative garlic NPs has an inhibitory effect on the growth of fungi, and different concentrations of HMON-garlic NPs-CS have an inhibitory effect on Coriolus versicolor. Through in vitro antibacterial tests, it can be obtained that the effective antibacterial concentration of HMON-garlic NPs-CS preservative is 0.06g / mL.

[0050] To investigate the leaching effect of garlic NPs and HMON-garlic NPs-CS when exposed to liquid water (anti-loss effect of preservatives), the drug loading and loss rate of garlic NPs and HMON-garlic NPs-CS at different concentrations were analyzed. Figure 5 It can be seen that the drug loading of garlic NPs and HMON-garlic NPs-CS gradually increases with the increase of concentration, and the drug loading and loss rate are negatively correlated, that is, the loss rate gradually decreases with the increase of drug loading. Under the same concentration, the loss rate of HMON-garlic NPs-CS is significantly lower than that of garlic NPs, indicating that the designed enzyme-responsive preservative can improve the anti-loss effect. This is because HMON-garlic NPs-CS can be evenly attached to the hierarchical structure of wood and form hydrogen bonds with the cell wall. In addition, the three-dimensional nano-network structure of silica further improves its fixation effect inside the wood, resulting in a lower loss rate.

[0051] In order to further explore the antiseptic effect and synergistic effect of enzyme-responsive preservatives. Different treatment groups were set up in the wood corrosion resistance test, namely garlic, garlic NPs and HMON-garlic NPs-CS treatment groups with different concentrations. To ensure the accuracy of the results, 5 groups of repeated tests were conducted on wood samples of each concentration. After 12 weeks, the weight loss rate of the wood was as follows: Figure 6 As shown in . It can be seen from the figure that the weight loss rate of the blank group wood sample reached 48.92%. When the wood sample was treated with garlic, the weight loss rate of the sample decreased with the increase of garlic concentration. When the concentration was 0.22g / mL, the weight loss rate of the wood was 33.67%, and the corrosion resistance level was level III, reaching a slightly corrosion resistance level. When the sample was treated with garlic NPs, its weight loss rate was low, and the weight loss rate of the samples treated with different concentrations was around 10%, indicating that it has excellent antifungal effect. When the concentration was 0.09g / mL, the weight loss rate was as low as 9.13%, and the wood sample at this concentration reached a strong corrosion resistance level. When the concentration was 0.06g / mL, the weight loss rate of the wood sample treated with HMON-garlic NPs-CS preservative was 12.13%, and the wood sample reached a corrosion resistance level. With the increase of concentration, the weight loss rate gradually decreased. When the concentration was 0.10g / mL, the treated sample reached a strong corrosion resistance level. By comparison, it can be found that when the concentration is close, the weight loss rate of the wood sample treated with the enzyme-responsive wood preservative is lower. In addition, the loading capacity of HMON microspheres for the preservative garlic NPs is 71.14±2.82%, indicating that the concentration of garlic NPs contained in the system is lower than the concentration of the direct impregnation agent, which reflects that the enzyme-responsive HMON-garlic NPs-CS has the effect of reducing the amount of preservatives and improving the utilization rate of preservatives. This is mainly attributed to the slow release and precise release of the responsive preservatives, as well as the ability to improve the stability and duration of the agent. Its effect on wood decay resistance is more obvious. When the hyphae of the colorful corium secretes laccase, the azo bonds on the surface of the microspheres are broken, causing the preservative garlic NPs inside the microspheres to be slowly released, inhibiting the growth of the colorful corium, and playing a role in wood protection. The construction of the chitosan-modified enzyme response system is expected to help the real "reduction in application and increase in efficiency" of preservatives.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a chitosan-modified enzyme-responsive wood preservative, characterized in that: The steps include: S1: preparing monodisperse silica nanoparticles by a preset method, synthesizing HMON with cavities, a preset specific surface area and a controllable mesoporous structure by a preset method on the basis of preparing monodisperse silica nanoparticles, and vigorously stirring ultrapure water, anhydrous ethanol and concentrated ammonia solution for a period of time to fully mix them; Add 6.2 mL of TEOS, stir at room temperature for 2 h, centrifuge, take the precipitate, wash it three times with ethanol and ultrapure water, and dissolve the precipitate SiO2 in 70 mL of ultrapure water for later use; Weigh 1.90g CTAC and 0.05g TEA and add them to 100mL ultrapure water, stir magnetically to fully dissolve them, continue stirring for 2h, add 35mL of the previously prepared SiO2 solution, stir magnetically for 1.5h, then add 2mL BTES to the above solution at 80℃, stir for 2h, centrifuge for 5min under the same conditions, take the precipitate and wash it with ethanol and ultrapure water twice in sequence, add 0.6M Na2CO3 to the above solution and stir at 80℃ for 2h, wash it with ethanol and ultrapure water at 8000r / min for 3 times to obtain a solid product; Finally, the solid product was extracted with a methanol solution dissolved in NaCl and stirred at room temperature overnight to remove the CTAC template. After centrifugation and washing, the product was freeze-dried to obtain HMON nanoparticles. S2: Weigh 200.00 mg HMON nanoparticles, dissolve in 60 mL ultrapure water, disperse evenly, add 450 μL APTES reagent, stir at room temperature for 10 h, centrifuge with ultrapure water 3 times, freeze-dry to obtain amino-functionalized HMON-NH2; S3: Weigh 75.00 g crushed garlic paste, dissolve in 250 mL ultrapure water, soak for 2 h, cook at a suitable temperature for 10 min, filter with gauze to obtain garlic crude extract. Mix 1 mL garlic extract, 0.09 g ethylenediamine, 1.00 g urea and 9 mL ultrapure water, and microwave treatment to obtain brown solid particles of garlic NPs; The mesopores on the surface of HMON were blocked by chitosan CS with biodegradable properties, and CS was encapsulated on the surface of HMON by grafting cleavable azo bonds on the surface of microspheres. S4: Add the preservative garlic NPs prepared in S3 to ultrapure water, prepare a garlic NPs aqueous solution of preset concentration with ultrapure water, dissolve HMON-NH2 in ultrapure water, disperse evenly, add it to the garlic NPs aqueous solution, stir at room temperature for 12 h, remove the supernatant after centrifugation, wash with ultrapure water for 3 times, and freeze-dry to obtain hollow mesoporous microspheres HMON-garlic NPs loaded with garlic NPs; S5: Weigh 0.30g of azobenzene-3,3'-dicarboxylic acid, add it to PBS solution, disperse it evenly by ultrasonication, stir it magnetically for 2h, add 0.45g of NHs and 0.75g of EDC to the dispersed solution, activate it for 3h, weigh 0.80g of the synthesized HMON-garlic NPs, dissolve it in 150mL of PBS solution, add it to the activated solution after it is completely dissolved, stir it at room temperature for 36h, synthesize HMON-garlic NPs-COOH, centrifuge it, rinse it with ethanol several times, freeze-dry it, and keep it for later use; S6: 0.50 g of the synthesized HMON-garlic NPs-COOH was placed in 100 mL PBS to fully dissolve it, 3 mg / mL NHs and 6 mg / mL EDC were added, and the activation treatment was carried out for 1.5 h. 0.16 g CS was weighed and added to 60 mL ultrapure water, and 0.6 mL acetic acid was added to prepare a CS solution. The CS solution was slowly poured into the above activated suspension, stirred at room temperature for 48 h, and the product was washed several times after centrifugation, and then freeze-dried in a freeze dryer to obtain HMON-garlic NPs-CS enzyme-responsive wood preservative.

2. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S1, the preset method includes Law.

3. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S1, the centrifugal treatment has a centrifugal speed of 10000 r / min and a centrifugal duration of 5 min.

4. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S3, the power of the microwave treatment is 500 W, and the microwave duration is 5 min.

5. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S4, the centrifugal treatment is carried out at a centrifugal rate of 8000 r / min and for a centrifugal time of 10 min.

6. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S5, the amount of the PBS solution added is 150 mL, and the pH of the PBS solution is 5.

8.

7. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S5, the centrifugal treatment is carried out at a centrifugal rate of 10000 r / min and for a centrifugal time of 5 min.

8. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S6, the centrifugal treatment is carried out at a centrifugal rate of 10000 r / min and for a centrifugal time of 5 min.

9. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S1, the added amounts of the ultrapure water, anhydrous ethanol and concentrated ammonia solution are 12 mL, 80 mL and 3.6 mL respectively.

10. The method for preparing a chitosan-modified enzyme-responsive wood preservative according to claim 1, characterized in that: In S1, the preset methods are nucleation, coating, punching and denucleation.

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