Hymexazol-loaded sodium alginate / carboxymethyl chitosan slow-release fibrous membrane and preparation method thereof
The preparation of sodium alginate/carboxymethyl chitosan sustained-release fiber membranes loaded with oxamylene using electrospinning technology solved the problem of oxamylene's easy decomposition and achieved stable drug release and environmentally friendly sustained-release effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EAST UNIV OF HEILONGJIANG
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-12
AI Technical Summary
In practical applications, oxamyl is easily decomposed and has a short duration of effect, resulting in unsustainable efficacy and potential threats to the environment.
A sodium alginate/carboxymethyl chitosan slow-release fiber membrane loaded with oxamyl was prepared by electrospinning technology. Polyvinyl alcohol was used as an auxiliary polymer to form physical cross-linking points through hydrogen bonding, thereby achieving the slow release of oxamyl.
The prepared fiber membrane has a stable morphology, is easy to store and transport, improves drug utilization, extends the efficacy period, reduces pesticide loss, and is environmentally friendly.
Smart Images
Figure CN122013450A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of agricultural chemical materials and nanotechnology, and more specifically, to a sodium alginate / carboxymethyl chitosan slow-release fiber membrane loaded with oxamyl and its preparation method. Background Technology
[0002] Hymexazol is a highly effective, low-toxicity systemic fungicide, and is also widely used as a soil disinfectant and plant growth regulator. However, due to its excellent water solubility, hymexazol is easily leached away by rainwater or irrigation water in field applications, resulting in a short effective period, low utilization rate, and potential environmental stress. Therefore, developing new pesticide formulations that can control hymexazol release, prolong its effective period, and reduce leaching is of significant practical importance.
[0003] Sodium alginate (SA) and carboxymethyl chitosan (CMCS) are both abundant, biocompatible, and biodegradable natural polysaccharides. In existing technologies, researchers have used these two materials to prepare hydrogels or fibers. For example, patent document CN113197200B discloses a method using oxadixyl itself as a "gelling agent" to trigger the formation of supramolecular hydrogels from sodium alginate and CMCS solutions. This study cleverly utilizes the hydrogen bonding between oxadixyl and the polysaccharide to construct a drug-loaded system. However, this technique produces a hydrogel with high water content, which limits its application in storage, transportation, and certain specific agricultural scenarios (such as seed coating and soil mixing) as a solid formulation.
[0004] Electrospinning is an effective method for preparing nanofiber membranes, resulting in membranes with extremely high specific surface area and porosity, making them ideal as drug carriers. However, since sodium alginate and carboxymethyl chitosan are both polyelectrolytes, strong electrostatic repulsion and hydrogen bonding exist between their molecular chains, making spinning them alone extremely difficult. Synthetic polymers are usually required as auxiliary polymers. Polyvinyl alcohol (PVA) is a good water-soluble and highly spinnable auxiliary polymer. Currently, there are no reports on combining electrospinning technology with the oxadixyl-triggered gelation mechanism to prepare solid nanofiber sustained-release drug delivery systems. Summary of the Invention
[0005] The technical problem to be solved by this invention is:
[0006] This addresses the technical problems of oxamyl in practical applications, such as easy decomposition, short effective period, and the threat to ecosystem stability posed by excessive use.
[0007] The purpose of this invention is to reduce the dosage of oxamyl, reduce off-target loss, and improve utilization rate, and to provide a solid composite nanofiber that is easy to store and transport and can achieve slow release of oxamyl and its preparation method.
[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:
[0009] This invention provides a method for preparing a sodium alginate / carboxymethyl chitosan sustained-release fiber membrane loaded with oxamyl, comprising the following steps;
[0010] (1) Preparation of sodium alginate / carboxymethyl chitosan spinning solution: Polyvinyl alcohol and sodium alginate are dissolved in deionized water to obtain a first solution, carboxymethyl chitosan is dissolved in deionized water to obtain a second solution, and finally the first solution and the second solution are mixed evenly to obtain the sodium alginate / carboxymethyl chitosan spinning solution.
[0011] (2) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan spinning solution: Add oxamyl to the sodium alginate / carboxymethyl chitosan spinning solution and mix evenly to obtain the oxamyl / sodium alginate / carboxymethyl chitosan spinning solution;
[0012] (3) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane: The oxamyl / sodium alginate / carboxymethyl chitosan spinning solution is added to an electrospinning device for electrospinning to obtain the oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane.
[0013] Furthermore, in step (1), the mass ratio of sodium alginate, carboxymethyl chitosan and polyvinyl alcohol is 1:1:10.
[0014] Further, the preparation method of the first solution in step (1) is as follows: add polyvinyl alcohol and sodium alginate to deionized water to make the pH of the solution 6-8, and stir continuously at 60°C and 500 rpm for 6 h to obtain the first solution.
[0015] Furthermore, the conditions for mixing the first and second solutions in step (1) are as follows: the pH of the mixture is 6-8, and the mixture is stirred continuously at 500 rpm for 6 h at 60°C.
[0016] Furthermore, the conditions for mixing oxamyl with the spinning solution in step (2) are: mixing at room temperature and at a gentle stirring speed of 300 rpm.
[0017] Furthermore, the mass percentage of oxamyl in the oxamyl / sodium alginate / carboxymethyl chitosan spinning solution in step (2) is 5%~25%.
[0018] Furthermore, the electrospinning conditions in step (3) are: spinning voltage of 15kV, spinning distance of 15cm, and feeding rate of 0.5mL / h.
[0019] Furthermore, the ambient temperature for electrospinning in step (3) is 25±2℃.
[0020] Furthermore, the ambient humidity for electrospinning in step (3) is 35±5%.
[0021] The present invention provides a sodium alginate / carboxymethyl chitosan slow-release fiber membrane loaded with oxamyl, wherein the fiber membrane is prepared by any of the methods described in the above technical solutions.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] 1. Morphological Innovation: For the first time, oxadixyl, sodium alginate, and carboxymethyl chitosan were prepared into a solid nanofiber membrane using electrospinning technology. This not only solves the problems of inconvenient storage and transportation of existing hydrogel formulations, but also utilizes the high specific surface area of nanofibers to improve the contact efficiency between the drug and the target.
[0024] 2. Synergistic Preparation Principle: This invention cleverly combines two mechanisms. First, the excellent spinnability of PVA is used as a "template" or "auxiliary" to drive the co-spinning of SA / CMCS, which is difficult to spin. Second, oxamyl is used as a gel trigger for SA / CMCS. After oxamyl is introduced into the spinning solution, physical cross-linking points are formed between oxamyl molecules and SA / CMCS molecular chains through interactions such as hydrogen bonds. This "pre-cross-linking" effect not only improves the stability of the spinning solution system but also plays a regulatory role in the subsequent fiber forming and release process.
[0025] 3. Excellent sustained-release performance: In the prepared nanofiber membrane, oxamyl is uniformly distributed in the polymer matrix. During use, after the fiber membrane comes into contact with water, the PVA dissolves and releases through the pores, while the SA / CMCS framework material slowly swells or degrades. At the same time, due to the affinity between oxamyl and the polysaccharide matrix, the slow release of oxamyl is achieved, effectively prolonging its effective period and reducing pesticide runoff.
[0026] 4. Environmentally friendly and safe: All raw materials are water-soluble or natural biodegradable materials, and the preparation process does not require the use of organic solvents, making it environmentally friendly; the preparation method is simple and the conditions are mild, and the resulting product has broad application prospects in the field of agricultural fungicides. Attached Figure Description
[0027] Figure 1 This is a scanning electron microscope (SEM) image of sodium alginate / carboxymethyl chitosan nanofibers without oxamyl loading in an embodiment of the present invention.
[0028] Figure 2 This is a scanning electron microscope (SEM) image of sodium alginate / carboxymethyl chitosan nanofibers loaded with 5% oxamyl in an embodiment of the present invention.
[0029] Figure 3 This is a scanning electron microscope (SEM) image of sodium alginate / carboxymethyl chitosan nanofibers loaded with 10% oxamyl in an embodiment of the present invention.
[0030] Figure 4 This is a scanning electron microscope (SEM) image of sodium alginate / carboxymethyl chitosan nanofibers loaded with 15% oxamyl in an embodiment of the present invention.
[0031] Figure 5 This is a scanning electron microscope (SEM) image of sodium alginate / carboxymethyl chitosan nanofibers loaded with 20% oxamyl in an embodiment of the present invention.
[0032] Figure 6 The image shows the infrared spectrum of the nanofibers in this embodiment of the invention.
[0033] Figure 7 The image shows the X-ray diffraction pattern of the nanofibers in this embodiment of the invention.
[0034] Figure 8 This is a thermogravimetric analysis diagram of the nanofibers in the embodiments of the present invention;
[0035] Figure 9 This is a cumulative release curve of oxamyl in the release medium of the nanofibers in the embodiments of the present invention;
[0036] Figure 10 This is a cumulative release curve of oxamyl in soil from nanofibers in an embodiment of the present invention;
[0037] Figure 11 This is a comparison diagram of the degradation of nanofibers in soil according to embodiments of the present invention. Detailed Implementation
[0038] To enable those skilled in the art to better understand the present invention, exemplary embodiments or examples of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments or examples are merely some, not all, of the embodiments or examples of the present invention. All other embodiments or examples obtained by those skilled in the art based on the embodiments or examples of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0040] This invention provides a method for preparing a sodium alginate / carboxymethyl chitosan sustained-release fiber membrane loaded with oxamyl, comprising the following steps;
[0041] (1) Preparation of sodium alginate / carboxymethyl chitosan spinning solution: Weigh 0.15 g sodium alginate and 1.5 g polyvinyl alcohol, dissolve in 10 mL deionized water, and continuously stir magnetically at 500 rpm for 6 h under constant temperature conditions of pH 6-8 and 60°C until completely dissolved to obtain the first solution. Weigh 0.15 g carboxymethyl chitosan, dissolve in 5 mL deionized water, and continuously stir magnetically at 500 rpm for 2 h under constant temperature conditions of pH 6-8 and 60°C until completely dissolved. Finally, mix the first solution and the second solution together, and continuously stir magnetically at 500 rpm for 2 h under constant temperature conditions of pH 6-8 and 60°C to ensure uniform mixing of all components to obtain the sodium alginate / carboxymethyl chitosan spinning solution.
[0042] (2) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan spinning solution: Oxamyl was added to the sodium alginate / carboxymethyl chitosan spinning solution at proportions of 0%, 5%, 10%, 15%, and 20% of the total solution mass, respectively. The solution was stirred at a gentle stirring speed of 300 rpm at room temperature to avoid generating too many bubbles. The stirring was continued for 2 h to ensure that the oxamyl was uniformly dispersed in the polymer matrix, thus obtaining the oxamyl / sodium alginate / carboxymethyl chitosan spinning solution.
[0043] (3) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane: 5 mL of the prepared spinning solution was loaded into a 10 mL plastic syringe, using a No. 21 stainless steel needle. The spinning voltage was set to 15 kV, the receiving distance to 15 cm, and the solution propulsion speed to 0.5 mL / h. The ambient temperature was controlled at 25±2°C, and the ambient humidity was controlled at 35±5%. An aluminum foil plate was used as the receiving device. Spinning was continued for 4 h and then stopped. The fiber membrane was carefully peeled off from the receiving device and placed in a vacuum drying oven at 40°C for 24 h to remove residual solvent. The dried oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane was stored in a desiccator for later use.
[0044] Example 2
[0045] 1. Simulated drug release from oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane: Square oxamyl / sodium alginate / carboxymethyl chitosan fiber membranes with sides of 3.0 cm were cut and placed in 50 mL centrifuge tubes. 20 mL of 0.1 mol / L hydrochloric acid solution was added to the centrifuge tubes as the release medium, and the tubes were quickly sealed to prevent moisture evaporation from affecting the experimental results. To simulate the actual planting release environment, the centrifuge tubes containing the oxamyl / sodium alginate / carboxymethyl chitosan fiber membranes and release medium were transferred to a thermostatically heated magnetic stirrer. The stirring frequency was set to 200 rpm, and the temperature was maintained at 25.0 ℃ to simulate the external environment. At predetermined time points of 0.5, 1, 2, 4, 8, 12, 24, and 48 h, 1 mL of the release solution was taken from the centrifuge tubes to measure the oxamyl content. After each sampling, immediately add 1 mL of 0.1 mol / L hydrochloric acid solution to ensure that the total volume of the release medium is always maintained at 20 mL, so as to maintain the consistency of experimental conditions.
[0046] 2. Actual drug release from the oxadixyl / sodium alginate / carboxymethyl chitosan fiber membrane: Northeast China black soil was used as the cultivation substrate. After sieving to remove impurities, 2.5 kg of soil was quantitatively filled into each pot. Before sowing, planting holes were prepared at equal intervals on the soil surface using a 1 cm diameter punch. Ten high-quality soybean seeds, rinsed three times with sterile water, were evenly sown in each pot to ensure consistent seed germination rates. The oxadixyl / carboxymethyl chitosan / sodium alginate / composite fiber membrane was directly and evenly spread over the soil surface in the pots. To avoid physical obstruction of seed germination by the fiber membrane, the planting holes were left uncovered during installation. All potted plants were uniformly placed in a greenhouse with a 16-hour light cycle followed by 8 hours of darkness, and water was regularly replenished to maintain soil moisture. Soil samples were collected on days 1, 3, 7, 14, 21, 28, and 35 after sowing. Using sterilized 10 mL centrifuge tubes, approximately 5.0 g of topsoil was collected from a depth of 0-3 cm by vertically inserting the tubes between two soybean plants in each pot. The collected soil samples were immediately frozen at -20 °C and then dehydrated using a vacuum freeze dryer. 3.0 g of the dried soil sample was accurately weighed and placed in a 50 mL centrifuge tube. 10 mL of 0.1 mol / L HCl extraction solution was added, and the tube was sealed and sonicated for 30 min to ensure complete dissolution of the oxadixyl in the soil. The sonicated sample was then allowed to stand in the dark at 4 °C for 12 h to promote solid-liquid separation, followed by high-speed centrifugation at 12000 rpm for 15 min. The supernatant was collected, and the oxadixyl content was measured.
[0047] Example 3
[0048] Degradation performance test of oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane:
[0049] Precision-cut square oxamyl / sodium alginate / carboxymethyl chitosan fiber membranes with sides of 3.0 cm were dried in an oven at 60°C. After drying and weighing, the undegradable fiber membranes were buried in flowerpot soil at a depth of approximately 10 cm. The membranes were periodically removed every 7 days, washed, dried, and weighed. The degradation rate was calculated using the following formula:
[0050] Degradation rate (%) = (Mm / M) × 100%
[0051] In the formula:
[0052] m—mass of the composite film after degradation, in g
[0053] M—Initial mass of the composite film, g.
[0054] Performance testing of oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane:
[0055] 1. Morphological characterization: The nanofibers prepared in Example 1 were observed by scanning electron microscopy (results are shown in Figure 1). Figure 1-5 As shown in the figure, the fiber surface is smooth, the diameter distribution is uniform, and there are no beads or droplets, indicating that the addition of PVA effectively improves the spinning performance of SA / CMCS.
[0056] 2. Structural characterization: Infrared spectroscopy analysis was performed on the nanofibers prepared in Example 1 (results are shown in Figure 1). Figure 6 (As shown). The results showed that the characteristic peaks of oxamyl coexisted with those of SA / CMCS / PVA, and some peak positions shifted, confirming the existence of hydrogen bonding interactions between oxamyl and the polymer matrix; X-ray diffraction analysis was performed on the fiber membrane prepared in Example 1 (results are shown). Figure 7 (As shown). The results showed that all fiber membranes exhibited characteristic diffraction peaks at 2θ = 19.4°, with a trend of gradually decreasing peak intensity. The characteristic peak at this point almost disappeared in the fiber membrane with 20% fiber addition, while this peak was a characteristic peak of PVA. This phenomenon occurred because the added oxamyl competitively disrupted the original hydrogen bond network molecules of the matrix material through its active hydroxyl and amino groups. This regular change confirmed that the introduction of oxamyl significantly reduced the crystallinity of the composite material. Thermogravimetric analysis was performed on the nanofibers prepared in Example 1 (results are shown). Figure 8 (As shown in the figure). The results show that the initial decomposition temperature of the composite fiber membrane is 250℃, and the maximum thermal decomposition temperature is about 285℃, indicating that it has good thermal stability in the operating temperature range below 200℃, meeting the requirements for conventional storage and application.
[0057] 3. Release experiment: The results of the simulated drug release are as follows: Figure 9As shown in the figure. The results indicate that all samples exhibited a significant sustained-release effect, but burst release also occurred; the higher the drug loading, the more pronounced the burst release effect; the actual drug release was as follows: Figure 10 As shown in the figure. The results indicate that the composite fiber membrane can continuously release oxamyl in the soil environment, and the higher the drug loading, the faster the initial release rate and the greater the cumulative release amount.
[0058] 4. Degradation Experiment: The degradation experiment in Example 3 is as follows... Figure 11 As shown, the results indicate that the addition of oxamyl significantly improved the degradation rate of the fiber membrane, but there was no significant difference in degradation rate among different addition amounts; the degradation process showed a trend of "rapid in the early stage and slow in the later stage", with 0-7 days being the rapid degradation period. This is because the introduction of oxamyl weakened the intermolecular forces and enhanced the hydrophilicity of the fiber membrane, thereby accelerating the microbial erosion and degradation process.
[0059] As can be seen, the oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane of the present invention, by introducing PVA-assisted spinning and combining the self-assembly between oxamyl and polysaccharides, successfully prepared a solid nanofiber drug-carrying system with good morphology and sustained-release function.
[0060] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A method for preparing a sodium alginate / carboxymethyl chitosan sustained-release fiber membrane loaded with oxamyl, characterized in that, Includes the following steps; (1) Preparation of sodium alginate / carboxymethyl chitosan spinning solution: Polyvinyl alcohol and sodium alginate are dissolved in deionized water to obtain a first solution, carboxymethyl chitosan is dissolved in deionized water to obtain a second solution, and finally the first solution and the second solution are mixed evenly to obtain the sodium alginate / carboxymethyl chitosan spinning solution. (2) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan spinning solution: Add oxamyl to the sodium alginate / carboxymethyl chitosan spinning solution and mix evenly to obtain the oxamyl / sodium alginate / carboxymethyl chitosan spinning solution; (3) Preparation of oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane: The oxamyl / sodium alginate / carboxymethyl chitosan spinning solution is added to an electrospinning device for electrospinning to obtain the oxamyl / sodium alginate / carboxymethyl chitosan fiber membrane.
2. The method according to claim 1, characterized in that, In step (1), the mass ratio of sodium alginate, carboxymethyl chitosan and polyvinyl alcohol is 1:1:
10.
3. The method according to claim 1, characterized in that, The preparation method of the first solution in step (1) is as follows: add polyvinyl alcohol and sodium alginate to deionized water to make the pH of the solution 6-8, and stir continuously at 60°C and 500 rpm for 6 hours to obtain the first solution.
4. The method according to claim 1, characterized in that, The conditions for mixing the first and second solutions in step (1) are: to make the pH of the mixture 6-8, and to stir continuously at 500 rpm for 6 h at 60°C.
5. The method according to claim 1, characterized in that, In step (2), the conditions for mixing oxamyl with the spinning solution are: mixing at room temperature and a gentle stirring speed of 300 rpm.
6. The method according to claim 1, characterized in that, The mass percentage of oxamyl in the spinning solution of oxamyl / sodium alginate / carboxymethyl chitosan in step (2) is 5% to 25%.
7. The method according to claim 1, characterized in that, The electrospinning conditions described in step (3) are: spinning voltage of 15kV, spinning distance of 15cm, and feeding rate of 0.5mL / h.
8. The method according to claim 1, characterized in that, The ambient temperature for electrospinning in step (3) is 25±2℃.
9. The method according to claim 1, characterized in that, The ambient humidity for electrospinning in step (3) is 35±5%.
10. A sodium alginate / carboxymethyl chitosan slow-release fiber membrane loaded with oxamyl, characterized in that, The fiber membrane is prepared by the method described in any one of claims 1-9.