A chitosan-MOF composite material, its preparation method and application
By preparing chitosan-MOF composite materials, the problem of adsorbing and controlling the release of plant growth regulators in existing technologies has been solved. This has enabled the efficient adsorption of aluminum ions and the intelligent release of naphthaleneacetic acid and tryptophan, thereby improving the plant's resistance to aluminum toxicity stress, reducing costs, and expanding the application areas.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JILIN UNIVERSITY
- Filing Date
- 2024-01-26
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies are difficult to use quickly and effectively to adsorb and control the release of plant growth regulators, and are costly, making it impossible to solve the problem of crop yield reduction caused by aluminum stress in a short period of time.
By using chitosan-MOFs composite materials, a composite material with both sponge and microsphere morphology is prepared by combining chitosan and metal-organic framework materials (MOFs). This composite material can efficiently adsorb aluminum ions and intelligently control the release of plant growth regulators naphthaleneacetic acid and tryptophan.
It significantly improves plant growth rate and yield, reduces usage costs, enables material recycling, and expands application potential in other fields.
Smart Images
Figure CN117732450B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of agricultural production technology, and particularly relates to a chitosan-MOFs composite material, its preparation method, and its application. Background Technology
[0002] Acidic soils account for about one-fifth of my country's total arable land area, and severe soil acidification severely restricts sustainable agricultural development. When the pH is around 5, aluminum in the soil will change from an insoluble form to a soluble exchangeable form (Al). 3+ Micromolar Al 3+ Aluminum ions can inhibit root elongation and affect normal physiological functions such as plant signal transduction, reactive oxygen species, and DNA, leading to stunted growth and eventual wilting and death. Therefore, reducing the aluminum ion content in the rhizosphere of crops or improving the plant's resistance to aluminum toxicity is particularly important for alleviating crop yield reduction caused by soil acidification.
[0003] Existing solutions to aluminum stress in plants mainly include improving soil physicochemical properties, applying aluminum ion adsorbents, and selecting aluminum-tolerant plant varieties. However, these solutions have the following drawbacks: 1) Improving soil physicochemical properties aims to create and maintain a soil environment conducive to plant growth. However, such traditional methods often require significant time and cost, making it difficult to quickly and effectively address yield reduction caused by aluminum toxicity stress. 2) Aluminum ion adsorbents have weak adsorption capacity for aluminum ions, making it difficult to effectively adsorb large amounts of aluminum ions in a short period. Furthermore, traditional adsorbents or antagonists have low adsorption efficiency, failing to achieve intelligent control over the release of plant growth regulators, resulting in the inability to release growth regulators in a timely manner when needed, thus affecting plant growth. In addition, traditional adsorbents are expensive and, due to the lack of recyclability, are typically used only once. 3) Aluminum-tolerant plant varieties with strong resistance can be selected and cultivated through natural or artificial selection. However, this method is subject to many limitations in actual production and is difficult to apply widely.
[0004] Metal-organic frameworks (MOFs), as nanomaterials with extremely high specific surface area, porosity, and tunable pore size / function, have made significant strides in environmental science and medicine as adsorbents for pollutants and carriers for controlled drug release systems. However, few studies have combined these two functions for agricultural applications. To alleviate aluminum stress in plants, we propose a chitosan-MOF composite material, its preparation method, and its applications. Summary of the Invention
[0005] The purpose of this invention is to provide a chitosan-MOFs composite material, its preparation method, and its application, in order to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A chitosan-MOFs composite material, comprising plant growth regulators, MOFs and chitosan as raw materials; wherein the plant growth regulators include naphthaleneacetic acid and tryptophan; and wherein the chitosan-MOFs composite material comprises NT@CS@UZ(s) and NT@CS@UZ(b).
[0008] A method for preparing chitosan-MOFs composite materials as described above, wherein the preparation steps of NT@CS@UZ(s) are as follows:
[0009] N@CS@U(s) was soaked in water, 350 mg of T@Z powder was added, and the mixture was stirred at 40 °C for 24 h. After repeating the freeze-drying step, CS@UiO-66@ZIF-8 sponge loaded with naphthaleneacetic acid and tryptophan, i.e., NT@CS@UZ(s), was finally obtained.
[0010] Furthermore, the preparation steps of the N@CS@U(s) are as follows:
[0011] Dissolve 500 mg of N@U powder in 10 mL of 2% HAc solution to obtain solution A; dissolve 1.5 g of CS powder in 40 mL of 2% HAc solution to obtain solution B; mix solution A and solution B at room temperature and stir for 12 h to obtain a mixed acid solution; pour the mixed acid solution into a suitable container for freeze-drying, and then repeatedly wash with ethanol and water until the solution is neutral, and repeat freeze-drying to finally obtain N@CS@U(s).
[0012] Furthermore, the preparation steps of the NT@CS@UZ(b) are as follows:
[0013] Weigh 1.5g of CS powder and dissolve it in 50mL of 2% HAc. Add 500mg of N@U powder and 350mg of T@Z powder. Stir at room temperature for 12h. Pour the CS acid solution into a suitable container and freeze-dry. Then wash repeatedly with ethanol and water until the solution is neutral and freeze-dry again to finally obtain CS@UiO-66@ZIF-8 microspheres loaded with naphthaleneacetic acid and tryptophan, namely NT@CS@UZ(b).
[0014] Furthermore, the preparation steps of the N@U powder are as follows:
[0015] 160 mg of ZrCl4 was dissolved in 40 mL of DMF and stirred until clear. 2.5 g of benzoic acid and 125 mg of terephthalic acid were added to the solution sequentially, and the mixture was stirred thoroughly. The solution was then transferred to a reaction vessel and heated at 120 °C for 24 h. After the system cooled to room temperature, the product was centrifuged at 10,000 rpm. The precipitate was washed with DMF and ethanol until the detergent was colorless, and then vacuum dried at 50 °C to obtain a white UiO-66 powder. UiO-66 and naphthaleneacetic acid were dispersed in water and stirred for 24 h. The product was centrifuged at 10,000 rpm, and the precipitate was washed with water and ethanol, and then vacuum dried at 50 °C to finally obtain UiO-66 powder loaded with naphthaleneacetic acid, i.e., N@U powder.
[0016] Furthermore, the preparation steps of the T@Z powder are as follows:
[0017] The steps for preparing the T@Z powder are as follows: Weigh 0.3g of zinc nitrate hexahydrate and dissolve it in 10mL of water, then weigh 4.5g of 2-methylimidazole and dissolve it in 70mL of water; after thoroughly mixing the two solutions, transfer them to a reaction vessel and heat them at 120℃ for 6h; after the system cools to room temperature, centrifuge the product at 10000r, wash the obtained precipitate with water and ethanol respectively, and dry it under vacuum at 50℃ to obtain ZIF-8 powder; disperse ZIF-8 and tryptophan in water and stir for 24h, centrifuge the product at 10000r, wash the obtained precipitate with water and ethanol respectively, and dry it under vacuum at 50℃ to finally obtain ZIF-8 powder loaded with tryptophan, i.e., T@Z powder.
[0018] Application of a chitosan-MOF composite material as described above in improving plant resistance to aluminum toxicity stress.
[0019] Compared with the prior art, the beneficial effects of the present invention are:
[0020] This chitosan-MOF composite material, its preparation method, and its applications.
[0021] This invention successfully prepared a chitosan-MOF composite material with both sponge and microsphere morphologies, exhibiting dual adsorption and controlled release functions. In the environment, this composite material can efficiently adsorb aluminum ions while intelligently controlling the release of plant growth regulators. The innovative, recyclable technology provided by this invention can significantly improve plant growth rate and yield while reducing usage costs. Based on the adsorption-controlled release dual function of this composite material, its application in other fields is expected to expand. Attached Figure Description
[0022] Figure 1This is a schematic diagram of the two morphologies of chitosan microspheres and chitosan sponges in this invention.
[0023] Figure 2 This is a schematic diagram of the adsorption-controlled release bifunctional chitosan-MOFs composite system in this invention for alleviating aluminum stress in plants and improving the rhizosphere microenvironment.
[0024] Figure 3 This is a diagram showing the overall morphology of the chitosan microspheres in this invention.
[0025] Figure 4 This is a diagram showing the overall morphology of the chitosan sponge in this invention.
[0026] Figure 5 This is a scanning electron microscope image of the chitosan microspheres in this invention.
[0027] Figure 6 This is a scanning electron microscope image of the chitosan sponge in this invention.
[0028] Figure 7 This is a scanning electron microscope image of NT@CS@UZ(s) in this invention.
[0029] Figure 8 This is a scanning electron microscope image of NT@CS@UZ(b) in this invention.
[0030] Figure 9 These are XRD patterns of the composite material before and after modification in this invention.
[0031] Figure 10 This invention illustrates the growth of the above-ground and underground parts of plants and changes in fresh weight under different treatments.
[0032] Figure 11 This describes the adsorption and desorption process of the composite material in this invention.
[0033] Figure 12 This refers to the multiple cyclic process of the composite material in this invention; wherein, (a) is T@CS@Z(s); (b) is T@CS@Z(b); (c) is N@CS@U(s); and (d) is N@CS@U(b). Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0035] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.
[0036] An embodiment of the present invention provides a chitosan-MOFs composite material, the raw materials of which include plant growth regulators, MOFs and chitosan; the plant growth regulators include naphthaleneacetic acid and tryptophan; the chitosan-MOFs composite material includes NT@CS@UZ(s) and NT@CS@UZ(b).
[0037] In this embodiment of the invention, preferably, the plant growth regulator loaded can be replaced with other amino acids, plant hormones, herbicides, fungicides, and other pesticides.
[0038] A method for preparing chitosan-MOFs composite materials as described above, wherein the preparation steps of NT@CS@UZ(s) are as follows:
[0039] N@CS@U(s) was soaked in water, 350 mg of T@Z powder was added, and the mixture was stirred at 40 °C for 24 h. After repeating the freeze-drying step, CS@UiO-66@ZIF-8 sponge loaded with naphthaleneacetic acid and tryptophan, i.e., NT@CS@UZ(s), was finally obtained.
[0040] In a preferred embodiment of the present invention, the preparation steps of N@CS@U(s) are as follows:
[0041] Dissolve 500 mg of N@U powder in 10 mL of 2% HAc solution to obtain solution A; dissolve 1.5 g of CS powder in 40 mL of 2% HAc solution to obtain solution B; mix solution A and solution B at room temperature and stir for 12 h to obtain a mixed acid solution; pour the mixed acid solution into a suitable container for freeze-drying, and then repeatedly wash with a large amount of ethanol and water until the solution is neutral, and repeat freeze-drying to finally obtain CS@UiO-66 sponge loaded with naphthaleneacetic acid, i.e., N@CS@U(s).
[0042] The preparation steps of T@CS@Z(s) are as follows:
[0043] Dissolve 350 mg of T@Z powder in 10 mL of 2% HAc solution to obtain solution A; dissolve 1.5 g of CS powder in 40 mL of 2% HAc solution to obtain solution B; mix solution A and solution B at room temperature and stir for 12 h to obtain a mixed acid solution; pour the mixed acid solution into a suitable container for freeze-drying, and then repeatedly wash with a large amount of ethanol and water until the solution is neutral, and repeat freeze-drying to finally obtain CS@ZIF-8 sponge loaded with tryptophan, i.e., T@CS@Z(s).
[0044] In a preferred embodiment of the present invention, the preparation steps of NT@CS@UZ(b) are as follows:
[0045] Weigh 1.5g of CS powder and dissolve it in 50mL of 2% HAc. Add 500mg of N@U powder and 350mg of T@Z powder. Stir at room temperature for 12h. Pour the CS acid solution into a suitable container and freeze-dry. Then wash repeatedly with ethanol and water until the solution is neutral and freeze-dry again to finally obtain CS@UiO-66@ZIF-8 microspheres loaded with naphthaleneacetic acid and tryptophan, namely NT@CS@UZ(b).
[0046] In a preferred embodiment of the present invention, the preparation steps of the N@U powder are as follows:
[0047] 160 mg of ZrCl4 was dissolved in 40 mL of DMF and stirred until clear. 2.5 g of benzoic acid and 125 mg of terephthalic acid were added to the solution sequentially, and the mixture was stirred thoroughly. The solution was then transferred to a reaction vessel and heated at 120 °C for 24 h. After the system cooled to room temperature, the product was centrifuged at 10,000 rpm. The precipitate was washed with DMF and ethanol until the detergent was colorless, and then vacuum dried at 50 °C to obtain a white UiO-66 powder. UiO-66 and naphthaleneacetic acid were dispersed in water and stirred for 24 h. The product was centrifuged at 10,000 rpm, and the precipitate was washed with water and ethanol, and then vacuum dried at 50 °C to finally obtain UiO-66 powder loaded with naphthaleneacetic acid, i.e., N@U powder.
[0048] In a preferred embodiment of the present invention, the preparation steps of the T@Z powder are as follows:
[0049] The steps for preparing the T@Z powder are as follows: Weigh 0.3g of zinc nitrate hexahydrate and dissolve it in 10mL of water, then weigh 4.5g of 2-methylimidazole and dissolve it in 70mL of water; after thoroughly mixing the two solutions, transfer them to a reaction vessel and heat them at 120℃ for 6h; after the system cools to room temperature, centrifuge the product at 10000r, wash the obtained precipitate with water and ethanol respectively, and dry it under vacuum at 50℃ to obtain ZIF-8 powder; disperse ZIF-8 and tryptophan in water and stir for 24h, centrifuge the product at 10000r, wash the obtained precipitate with water and ethanol respectively, and dry it under vacuum at 50℃ to finally obtain ZIF-8 powder loaded with tryptophan, i.e., T@Z powder.
[0050] As a preferred embodiment of the present invention, the preparation steps of chitosan microspheres CS(b) are as follows:
[0051] First, 1.5 g of low-viscosity chitosan powder was weighed and dissolved in 50 mL of 2% HAc and stirred for 12 h. Using a pipette, the overnight-stirred chitosan acid solution was added dropwise to 300 mL of pre-prepared 1 mol / L NaOH alkaline solution, and stirred for 12 h. The solution was repeatedly washed with a large amount of ethanol and water until neutral, then freeze-dried to obtain chitosan microspheres.
[0052] As a preferred embodiment of the present invention, the preparation steps of chitosan sponge CS(s) are as follows:
[0053] First, weigh 1.5g of low-viscosity chitosan powder and dissolve it in 50mL of 2% HAc, stirring at room temperature for 12h. Pour the chitosan acid solution into a suitable container and freeze-dry. Wash repeatedly with a large amount of ethanol and water until the solution is neutral, then repeat the freeze-drying process to finally obtain chitosan sponge.
[0054] In this embodiment of the invention, to ensure that the composite material is easily recyclable in different environments, two forms, microspheres and sponges, were designed and synthesized (e.g., Figure 1 As shown in the figure, Chitosan beads are chitosan microspheres and Chitosan sponge is chitosan sponge.
[0055] The overall morphology of chitosan microspheres and chitosan sponges is as follows: Figure 3 and Figure 4 As shown.
[0056] The microstructure of chitosan microspheres and chitosan sponges are as follows Figure 5 and Figure 6 As shown.
[0057] The resulting composite materials were subjected to basic characterization and exploration of their structure and properties, including SEM (Structured Electron Microscopy). Figure 7 and Figure 8 ) and XRD Figure 9 )wait.
[0058] As can be seen from the XRD, NT@CS@UZ(s) and NT@CS@UZ(b) have the characteristic peaks of each component, further verifying the successful synthesis of the material.
[0059] One embodiment of the present invention provides the application of a chitosan-MOFs composite material as described above in improving plant resistance to aluminum toxicity stress.
[0060] In this embodiment of the invention, the specific operation is as follows: a 50-100mM aluminum chloride solution is prepared to simulate an aluminum toxic environment, and NT@CS@UZ(s) and NT@CS@UZ(b) are added to observe the effect on crop growth.
[0061] See Figure 2ZIF-8 can rapidly release its loaded tryptophan in the initial acidic environment to maintain plant growth without accelerating root growth, thus preventing the roots from absorbing large amounts of aluminum ions and exacerbating toxicity. During this process, chitosan and MOFs adsorb large amounts of aluminum ions from the environment, gradually reducing their concentration. Subsequently, UiO-66 slowly releases naphthaleneacetic acid, promoting root growth and further mitigating the harm caused by aluminum toxicity to plants. This chitosan-MOFs composite system not only possesses the dual functions of intelligent adsorption and controlled release, but its sponge and microsphere forms also greatly increase its practicality in real-world applications and facilitate recycling.
[0062] The growth of aboveground and underground parts of plants and changes in fresh weight under different material treatments are as follows: Figure 10 As shown, the root and stem length and fresh weight of wheat treated with different materials for 6 days were statistically analyzed. Increased aluminum content severely impacted plants, especially root growth. Chitosan, naphthaleneacetic acid, and tryptophan promoted plant growth under stable and suitable growing conditions, but their effects were not significant under aluminum toxicity conditions. Plants treated with NT@CS@UZ(s) and NT@CS@UZ(b) were able to largely recover to normal growth.
[0063] The adsorption and desorption processes of composite materials are as follows: Figure 11 As shown, both the NT@CS@UZ(s) and NT@CS@UZ(b) systems can rapidly load the two compounds and be reused after desorption. Due to the stronger stability of UiO-66 under slightly acidic conditions, the desorbed material exhibits better compound loading performance than ZIF-8.
[0064] Multiple cyclic processes of composite materials, such as Figure 12 As shown, both NT@CS@UZ(s) and NT@CS@UZ(b) systems can be recycled multiple times while maintaining a high utilization rate. The poor cycling performance of Trp@CS@ZIF-8(s) is mainly due to the lower stability of ZIF-8 under acidic conditions compared to UiO-66. However, it still achieves a utilization rate of over 60% after five cycles.
[0065] In summary, the chitosan-MOFs composite material synthesized in this invention has the following characteristics:
[0066] 1) The composite material not only has a high specific surface area, enabling efficient adsorption of aluminum ions, but also has an intelligent controlled release function, which can release growth regulators according to the needs of plants.
[0067] 2) The composite material is designed as microspheres to increase its contact area with the environment, thereby improving adsorption efficiency. The sponge-like state acts as filter paper in hydroponics, which is more conducive to the growth of plant roots in its larger pores. At the same time, both forms are also convenient for subsequent recycling.
[0068] 3) When the composite material is placed in an environment containing aluminum ions, its high specific surface area and specific chemical properties enable it to rapidly adsorb aluminum ions. ZIF-8 releases tryptophan under acidic conditions, accelerating plant growth. As the rhizosphere aluminum ion content decreases, UiO-66 slowly releases naphthaleneacetic acid, significantly promoting root growth and further mitigating the damage caused by aluminum toxicity to plants. This composite material intelligently releases regulators according to the needs of the plant and environmental conditions. This process is automatic and requires no external intervention.
[0069] 4) Once the adsorption-controlled release phase is complete, the composite material can be restored to its original state through simple elution and drying steps, thereby achieving recycling.
[0070] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.
Claims
1. A chitosan-MOF composite material for improving plant resistance to aluminum toxicity stress, characterized in that, The raw materials include plant growth regulators, MOFs and chitosan; the plant growth regulators include naphthaleneacetic acid and tryptophan; the chitosan-MOFs composite material is a CS@UiO-66@ZIF-8 sponge loaded with naphthaleneacetic acid and tryptophan, denoted as NT@CS@UZ(s).
2. A method for preparing a chitosan-MOF composite material for improving plant resistance to aluminum toxicity stress according to claim 1, characterized in that, The preparation steps of the NT@CS@UZ(s) are as follows: N@CS@U(s) was soaked in water, 350 mg of T@Z powder was added, and the mixture was stirred at 40°C for 24 h. After repeating the freeze-drying step, CS@UiO-66@ZIF-8 sponge loaded with naphthaleneacetic acid and tryptophan, i.e., NT@CS@UZ(s), was finally obtained.
3. The preparation method according to claim 2, characterized in that, The preparation steps of N@CS@U(s) are as follows: Dissolve 500 mg of N@U powder in 10 mL of 2% HAc solution to obtain solution A; dissolve 1.5 g of CS powder in 40 mL of 2% HAc solution to obtain solution B; mix solution A and solution B at room temperature and stir for 12 h to obtain a mixed acid solution. The mixed acid solution was poured into a suitable container and freeze-dried. Then, it was repeatedly washed with ethanol and water until the solution was neutral, and then freeze-dried again to finally obtain CS@UiO-66 sponge loaded with naphthaleneacetic acid, i.e., N@CS@U(s).
4. The preparation method according to claim 3, characterized in that, The preparation steps of the N@U powder are as follows: 160 mg of ZrCl4 was weighed and dissolved in 40 mL of DMF and stirred until clear. 2.5 g of benzoic acid and 125 mg of terephthalic acid were added to the solution sequentially, and after thorough stirring, the solution was transferred to a reaction vessel and heated at 120 °C for 24 h. After the system cooled to room temperature, the product was centrifuged at 10,000 r. The obtained precipitate was washed with DMF and ethanol until the detergent was colorless, and then vacuum dried at 50 °C to obtain UiO-66 white powder. UiO-66 and naphthaleneacetic acid were dispersed in water and stirred for 24 h. The product was centrifuged at 10,000 r, and the obtained precipitate was washed with water and ethanol, and then vacuum dried at 50 °C to finally obtain UiO-66 powder loaded with naphthaleneacetic acid, i.e., N@U powder.
5. The preparation method according to claim 2, characterized in that, The preparation steps of the T@Z powder are as follows: The steps for preparing the T@Z powder are as follows: 0.3 g of zinc nitrate hexahydrate is dissolved in 10 mL of water, and 4.5 g of 2-methylimidazole is dissolved in 70 mL of water. The two solutions are thoroughly mixed and transferred to a reaction vessel, heated at 120 °C for 6 h. After the system cools to room temperature, the product is centrifuged at 10,000 r. The precipitate is washed with water and ethanol until the detergent is colorless, and then vacuum dried at 50 °C to obtain ZIF-8 powder. ZIF-8 and tryptophan are dispersed in water and stirred for 24 h. The product is centrifuged at 10,000 r. The precipitate is washed with water and ethanol, and then vacuum dried at 50 °C to finally obtain ZIF-8 powder loaded with tryptophan, i.e., T@Z powder.
6. The application of the chitosan-MOFs composite material according to claim 1 for improving plant resistance to aluminum toxicity stress in improving plant resistance to aluminum toxicity stress.