Cinnamaldehyde sustained-release hydrogel particles, a preparation method thereof and application thereof in bird damage bird repellent

Abstract

The present application belongs to the field of hydrogel preparation and bird repellent technology, and particularly relates to a cinnamaldehyde sustained-release hydrogel particle, a preparation method thereof and application thereof in bird damage bird repellent. The present application takes cinnamaldehyde, carboxymethyl chitosan, water, an emulsifier and a metal ion crosslinking agent as raw materials, and by adjusting the volume-mass ratio of cinnamaldehyde and carboxymethyl chitosan, the volume ratio of cinnamaldehyde and water, and the concentration of metal ions in the metal ion crosslinking agent, particles in regular spherical shape, uniform morphology, no adhesion, smooth surface and uniform particle size can be obtained, and the particles have high drug loading capacity, good encapsulation efficiency, sustained-release effect without obvious burst release, long effective period and significant pH responsiveness, and can regulate the release rate of cinnamaldehyde according to the change of environmental pH. The repellency rate continuously increases with the increase of the dose, and the repellency rate of 90 g / m 2 The treatment repellency rate reaches 93.40%, which shows excellent and stable antifeeding effect on birds, and is beneficial to prolong the effective time of bird repellent and reduce the labor cost of frequent application.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel preparation and bird repellency technology, specifically relating to a cinnamaldehyde slow-release hydrogel particle, its preparation method, and its application in bird pest control. Background Technology

[0002] Agricultural pests refer to birds that, in large populations, peck at grain seeds, fruit trees, or flower petals and buds, causing significant economic losses. Bird damage to crops is mainly concentrated during the sowing, seedling, grain-filling, and harvesting stages. For example, during the sowing period, sparrows, doves, and crows directly feed on direct-seeded rice seeds, leading to severe seedling loss, and in some areas, this has even hindered the promotion of direct-seeded rice technology. During the seedling stage, pigeons and spotted doves peck at corn and soybean seeds, causing gaps in the seedlings.

[0003] To combat bird damage during the sowing and seedling stages, seed treatment is commonly used. Currently, seed coating agents with insecticides such as carbofuran and imidacloprid as active ingredients, while having some bird-repelling effect, are highly toxic to birds and do not meet the requirements of sustainable agricultural development. Physical measures such as sound deterrence and setting up bird nets are costly and cumbersome. In recent years, bird repellents have received increasing attention due to their environmental friendliness, economy, effectiveness, and ease of use. Bird repellents are generally biological agents processed from pure natural raw materials. After application, they release a special pleasant aroma that affects the nervous and respiratory systems of birds, causing them to fly away and not return for a period of time. However, existing bird repellents evaporate quickly, have a short duration of use, require regular replenishment, and are inconvenient to use. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a formulation with sustained-release effect, long effective duration, reduced bird damage, and good repellency effect on birds.

[0005] To achieve the above objectives, the present invention provides cinnamaldehyde sustained-release hydrogel particles, wherein the cinnamaldehyde sustained-release hydrogel particles comprise the following raw materials: cinnamaldehyde, carboxymethyl chitosan, water, emulsifier and metal ion crosslinking agent. The volume-to-mass ratio of cinnamaldehyde to carboxymethyl chitosan is 1 mL: 0.4 g; The volume ratio of cinnamaldehyde to water is 1:10; The concentration of metal ions in the metal ion crosslinking agent is 0.3 mol / L.

[0006] Preferably, the metal ions include one or more of manganese ions, calcium ions, copper ions, and zinc ions; The volume ratio of cinnamaldehyde to emulsifier is 100:2.

[0007] Preferably, the emulsifier includes Tween 80.

[0008] The present invention also provides a method for preparing cinnamaldehyde sustained-release hydrogel particles as described in the above technical solution, characterized by comprising the following steps: Cinnamaldehyde and an emulsifier are mixed to obtain a cinnamaldehyde solution; Mix carboxymethyl chitosan and water to make a carboxymethyl chitosan aqueous solution; The cinnamaldehyde solution and the carboxymethyl chitosan aqueous solution were mixed and emulsified to obtain an O / W emulsion. The O / W emulsion was added dropwise to a metal ion crosslinking agent and cured to obtain the cinnamaldehyde sustained-release hydrogel particles.

[0009] Preferably, the emulsification rotation speed is 8000~12000 r / min and the time is 3~6 min; The curing temperature is 20~30℃ and the time is 3~6 h.

[0010] Preferably, the method further includes: freeze-drying the cinnamaldehyde sustained-release hydrogel particles to obtain freeze-dried cinnamaldehyde sustained-release hydrogel particles.

[0011] The present invention also provides the application of the cinnamaldehyde sustained-release hydrogel particles described in the above technical solution or the cinnamaldehyde sustained-release hydrogel particles prepared by the above technical solution in bird control.

[0012] Preferably, the birds that cause bird damage include the white-rumped munia.

[0013] The present invention also provides a bird repellent, wherein the active ingredient of the bird repellent includes the cinnamaldehyde sustained-release hydrogel particles described in the above technical solution or the cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method described in the above technical solution.

[0014] The present invention also provides a bird-repelling method according to the above-mentioned technical solution, comprising the following steps: applying the cinnamaldehyde slow-release hydrogel particles described in the above-mentioned technical solution or the cinnamaldehyde slow-release hydrogel particles prepared by the above-mentioned technical solution to an area where bird damage is frequent. The application amount of the cinnamaldehyde sustained-release hydrogel particles is ≥30 g / m³. 2 .

[0015] Beneficial effects: This invention prepares hydrogel particles using cinnamaldehyde, carboxymethyl chitosan, water, emulsifier, and metal ion crosslinking agent as raw materials. By adjusting the volume-to-mass ratio of cinnamaldehyde and carboxymethyl chitosan, the volume ratio of cinnamaldehyde and water, and the concentration of metal ions in the metal ion crosslinking agent, regularly spherical, uniformly shaped, non-adhesive, smooth-surfaced, and uniformly sized particles can be obtained, exhibiting high drug loading and good encapsulation efficiency. The cinnamaldehyde sustained-release hydrogel particles obtained by this invention have a sustained-release effect with no obvious burst release, a long duration of effect, and significant pH responsiveness, and can regulate the release rate of cinnamaldehyde according to changes in environmental pH. The release rate is within the range of 30~90 g / m³. 2 Within the applied dosage range, the repellency rate continuously increased with increasing dose, and the marginal effect per unit dose did not diminish, maintaining good synergistic potential even at high doses. 90 g / m 2 The treatment achieved a repellency rate of 93.40%, demonstrating an excellent and stable bird deterrent effect, which is beneficial for extending the effective bird deterrent time and reducing the labor costs of frequent application in practical field applications. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0017] Figure 1 The particle morphology of different cinnamaldehyde sustained-release hydrogel particles is shown in the figure. Figure 2 Morphological characterization of cinnamaldehyde sustained-release hydrogel particles; where A is a photograph of freshly prepared cinnamaldehyde sustained-release hydrogel particles; B and C are cryo-electron micrographs of freshly prepared cinnamaldehyde sustained-release hydrogel particles; D and E are scanning electron micrographs of cinnamaldehyde sustained-release hydrogel particles obtained by freeze-drying. Figure 3 This is an infrared spectrum analysis diagram; Figure 4 This is an elemental mapping analysis diagram of the energy spectrum; Figure 5 Release curves of cinnamaldehyde sustained-release hydrogel particles at different pH values; Figure 6 To investigate the repellent effect of cinnamaldehyde sustained-release hydrogel particles on white-rumped munias at different dosages; Figure 7 The effect of cinnamaldehyde sustained-release hydrogel particles on white-rumped munias at different time points. Detailed Implementation

[0018] This invention provides cinnamaldehyde sustained-release hydrogel particles, which comprise the following raw materials: cinnamaldehyde, carboxymethyl chitosan, water, emulsifier, and metal ion crosslinking agent; the volume-to-mass ratio of cinnamaldehyde to carboxymethyl chitosan is 1 mL: 0.4 g; the volume ratio of cinnamaldehyde to water is 1:10; and the concentration of metal ions in the metal ion crosslinking agent is 0.3 mol / L.

[0019] This invention uses carboxymethyl chitosan as a carrier, which, compared with other matrix materials, has good biocompatibility, is biodegradable, rich in carboxyl and amino active sites, and is easy to crosslink and modify.

[0020] As one embodiment, the metal ions described in this invention include one or more of manganese ions, calcium ions, copper ions, and zinc ions. The metal ions provided by this invention can form stable coordination crosslinks with the carboxyl and amino groups of carboxymethyl chitosan to construct a three-dimensional gel network, and are low in toxicity and safe.

[0021] In one embodiment, the volume ratio of cinnamaldehyde to emulsifier in this invention is 100:2. This volume ratio of cinnamaldehyde to emulsifier enables the formation of a stable O / W emulsion, preventing cinnamaldehyde precipitation and thereby improving drug loading and encapsulation efficiency.

[0022] In one embodiment, the emulsifier of this invention includes Tween 80. This invention limits the type of emulsifier; compared to other types of emulsifiers, Tween 80 exhibits the best emulsifying stabilizing effect on cinnamaldehyde and is non-toxic.

[0023] This invention strictly limits the volume-to-mass ratio of cinnamaldehyde and carboxymethyl chitosan, the volume ratio of cinnamaldehyde and water, and the concentration of metal ions in the metal ion crosslinking agent, which can produce particles that are regularly spherical, uniform in shape, non-adhesive, smooth in surface, and uniform in size, and have high drug loading and good encapsulation efficiency.

[0024] The present invention also provides a method for preparing cinnamaldehyde sustained-release hydrogel particles as described in the above technical solution, characterized by comprising the following steps: Cinnamaldehyde and an emulsifier are mixed to obtain a cinnamaldehyde solution; Mix carboxymethyl chitosan and water to make a carboxymethyl chitosan aqueous solution; The cinnamaldehyde solution and the carboxymethyl chitosan aqueous solution were mixed and emulsified to obtain an O / W emulsion. The O / W emulsion was added dropwise to a metal ion crosslinking agent and cured to obtain the cinnamaldehyde sustained-release hydrogel particles.

[0025] In one embodiment, the emulsification rotation speed of the present invention is 8000~12000 r / min; in another embodiment, the emulsification rotation speed of the present invention is 10000 r / min. In one embodiment, the emulsification time of the present invention is 3~6 min; in another embodiment, the emulsification time of the present invention is 5 min.

[0026] In one embodiment, the present invention utilizes a syringe with a needle to dropwise add the O / W emulsion to a metal ion crosslinking agent. In another embodiment, the inner diameter of the needle is 0.6 mm. By limiting the inner diameter of the needle, the present invention can control the droplet size, thereby obtaining spherical particles with uniform particle size.

[0027] In one embodiment, the curing temperature of the present invention is 20~30℃; in another embodiment, the curing temperature of the present invention is 25℃. In one embodiment, the curing time of the present invention is 3~6 h; in another embodiment, the curing time of the present invention is 4 h.

[0028] In one embodiment, after obtaining the cinnamaldehyde sustained-release hydrogel particles, the present invention freeze-dries the cinnamaldehyde sustained-release hydrogel particles to obtain freeze-dried cinnamaldehyde sustained-release hydrogel particles. The freeze-drying conditions of the present invention are: freezing at -80°C for 24 hours, then placing in a freeze dryer with a cold trap temperature of -50°C to -80°C for 48 hours. The freeze-drying process of the present invention can remove moisture, form a porous structure, facilitate long-term storage and transportation, and further regulate the sustained-release performance.

[0029] The cinnamaldehyde sustained-release hydrogel particles provided by this invention have a sustained-release effect with no obvious burst release, long duration of effect and significant pH responsiveness. They can regulate the release rate of cinnamaldehyde according to changes in environmental pH, which is beneficial for extending the effective bird-repelling time and reducing the labor cost of frequent application in practical field applications.

[0030] Given the advantages of the cinnamaldehyde sustained-release hydrogel particles provided by this invention, the application of the cinnamaldehyde sustained-release hydrogel particles described in the above technical solution or the cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method described in the above technical solution in bird control is also within the scope of protection of this invention.

[0031] In one embodiment, the birds that cause bird damage according to the present invention include the white-rumped munia.

[0032] The present invention also provides a bird repellent, wherein the active ingredient of the bird repellent includes the cinnamaldehyde sustained-release hydrogel particles described in the above technical solution or the cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method described in the above technical solution.

[0033] In one embodiment, the bird repellent of the present invention also includes excipients. The present invention does not have strict requirements on the type of excipients; conventional selection is acceptable.

[0034] The present invention also provides a bird-repelling method according to the above-mentioned technical solution, comprising the following steps: applying the cinnamaldehyde slow-release hydrogel particles described in the above-mentioned technical solution or the cinnamaldehyde slow-release hydrogel particles prepared by the above-mentioned technical solution to an area where bird damage is frequent. The application amount of the cinnamaldehyde sustained-release hydrogel particles is ≥30 g / m³. 2 .

[0035] As one embodiment, the application amount of the cinnamaldehyde sustained-release hydrogel particles of the present invention is 60~90 g / m³. 2 The cinnamaldehyde sustained-release hydrogel particles of this invention exhibit dose-dependent release at concentrations ranging from 30 to 90 g / m³. 2 Within the experimental range, the avoidance rate continuously increased with increasing dose, and the marginal effect per unit dose did not diminish, maintaining good synergistic potential even at high doses. 90 g / m 2 The treatment achieved a repellency rate of 93.40%, demonstrating an excellent and stable antifeeding effect on the white-rumped munia. This invention does not have strict requirements regarding the timing of application of the cinnamaldehyde slow-release hydrogel particles; it can be selected conventionally based on the occurrence of bird damage.

[0036] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes a cinnamaldehyde sustained-release hydrogel particle, its preparation method, and its application in bird control. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1 The preparation method of cinnamaldehyde sustained-release hydrogel particles consists of the following steps: 1. Mix carboxymethyl chitosan and water to obtain a 4% (w / w) carboxymethyl chitosan aqueous solution.

[0038] 2. Add 2% Tween 80 to cinnamaldehyde to obtain a cinnamaldehyde-Tween solution, with a volume ratio of cinnamaldehyde to Tween of 100:2. 3. Mix the carboxymethyl chitosan aqueous solution and the cinnamaldehyde-Tween solution at a volume ratio (oil-water ratio) of 1:10 and shear at a shear rate of 10000 r / min for 5 min to form an O / W emulsion.

[0039] 2. Place the O / W emulsion into a syringe with a #6 needle (0.6 mm inner diameter) and add it dropwise to Mn. 2+ Cinnamaldehyde sustained-release hydrogel particles were obtained by curing in solution at 25°C for 4 h; wherein, Mn 2+ Mn in solution2+ The concentration is 0.3 mol / L.

[0040] 3. After freezing the cinnamaldehyde sustained-release hydrogel in a -80℃ freezer for 24 hours, freeze-dry it in a freeze dryer (cold trap temperature -50℃~-80℃) for 48 hours to obtain freeze-dried cinnamaldehyde sustained-release hydrogel particles.

[0041] Comparative Examples 1-8 The preparation method is similar to that of the cinnamaldehyde sustained-release hydrogel particles in Example 1, except that the mass concentration of carboxymethyl chitosan, the oil-to-water ratio, and the Mn content in the carboxymethyl chitosan solution are different. 2+ Mn in solution 2+ One or more of the concentrations are different, and the specific differences are listed in Table 1 below.

[0042] Table 1. Preparation parameters of cinnamaldehyde sustained-release hydrogel particles in Example 1 and Comparative Examples 1-8

[0043] Comparative Example 9 The preparation of blank hydrogel particles consists of the following steps: 1. Mix carboxymethyl chitosan aqueous solution and Tween 80 at a volume ratio of 100:2, shear at a high speed of 10000 r / min for 5 min, place in a syringe with a #6 needle (inner diameter of 0.6 mm), and add dropwise to Mn. 2+ In the solution, the mixture was cured at 25°C for 4 h to obtain blank hydrogel particles; wherein, the mass concentration of carboxymethyl chitosan in the aqueous solution was 4%, and Mn 2+ Mn in solution 2+ The concentration is 0.3 mol / L.

[0044] 2. The blank hydrogel was freeze-dried to obtain freeze-dried blank hydrogel particles.

[0045] Test Example 1 1. Referring to existing technology (Wang Zhao, Yin Mingming, Chen Fuliang. Preparation and performance study of sodium alginate-chitosan encapsulated granules of abamectin B2 [J]. Journal of Pesticide Science, 2017, 19: 744-754), a dissociation solution (aqueous solution of 0.06 M trisodium citrate dihydrate and 0.2 M NaHCO3) was prepared. 10 mg of lyophilized cinnamaldehyde sustained-release hydrogel particles obtained in Example 1 and Comparative Examples 1-8 were taken respectively, added to 5 mL of the dissociation solution, sonicated for 1 h, added to a 10 mL volumetric flask, and diluted to 10 mL with methanol. The mixture was shaken for 20 min and filtered through a 0.22 μm organic filter membrane. The content of cinnamaldehyde was detected by high performance liquid chromatography. The drug loading and encapsulation efficiency were calculated according to the following formula. The results are shown in Table 2.

[0046] Drug loading (%) = (mass of cinnamaldehyde / mass of gel particles) × 100%; Encapsulation rate (%) = (Cinnamaldehyde test quality / Cinnamaldehyde addition amount) × 100%.

[0047] Table 2. Results of drug loading and encapsulation efficiency of cinnamaldehyde sustained-release hydrogel particles in Examples 1 and Comparative Examples 1-8

[0048] As shown in Table 2, Experiment 2 (Comparative Example 2) and Experiment 3 (Comparative Example 3) failed to form spheres during the preparation process, and the materials were directly dispersed in Mn. 2+ The failure to form a complete hydrogel spherical structure in the solution indicates that the strength of the carboxymethyl chitosan molecular network is insufficient to maintain the spherical shape.

[0049] 2. Based on the conclusions of step 1, the particle morphology of the cinnamaldehyde sustained-release hydrogel particles obtained after freeze-drying in Example 1 and Comparative Examples 1, 4-8 was further observed, and the results are as follows: Figure 1 As shown. According to Figure 1 As can be seen, the hydrogel obtained in Experiment 7 (Example 1) is visually spherical with uniform morphology and no adhesion, significantly superior to the other groups. Furthermore, its drug loading (32.63%±0.72%) and encapsulation efficiency (18.67%±0.41%) remain at a high level, demonstrating both good cinnamaldehyde loading capacity and molding quality. Although Experiment 1 (Comparative Example 1) had the highest drug loading (49.46%), and Experiment 6 (Comparative Example 6) had a slightly better encapsulation efficiency (20.20%±2.61%), both exhibited poor particle morphological uniformity. The hydrogel obtained in Example 1 demonstrates a balance between molding stability, macroscopic morphological regularity, and drug loading performance.

[0050] Test Example 2 Scanning electron microscopy (SEM) analysis The freshly prepared cinnamaldehyde sustained-release hydrogel particles from Example 1 were regular spherical in shape, milky white in appearance, with a smooth surface and uniform particle size. Figure 2 To further reveal its microstructure, cryo-transmission electron microscopy was used for observation. The hydrogel particles exhibited obvious internal and external heterogeneous morphological characteristics: the interior was uniformly distributed with a large number of micropores, forming a three-dimensional network structure, and the active ingredient cinnamaldehyde was tightly wrapped in the network pores; while the surface was mainly composed of a dense structure, presenting a relatively smooth and complete interface. Figure 2 (B and C). Scanning electron microscopy observation of the cinnamaldehyde sustained-release hydrogel particles (lyophilized samples) obtained by freeze-drying revealed that the average particle size of the cinnamaldehyde sustained-release hydrogel particles was approximately 1.8 mm, and the surface formed a dense and undulating wrinkled morphology due to dehydration. Figure 2(D and E); Internal cross-sectional images show that the matrix contains large, unevenly distributed pores. Figure 2 (F and G).

[0051] Test Example 3 FT-IR spectroscopy analysis Carboxymethyl chitosan (CMCS), cinnamaldehyde (CA), the blank hydrogel (B-CMCS) obtained in Comparative Example 9, and the cinnamaldehyde sustained-release hydrogel (CMCS-CA) prepared in Example 1 were analyzed by Fourier transform infrared spectroscopy (FT-IR).

[0052] The results are as follows Figure 3 As shown, CMCS is at 3443 cm -1 The broad absorption peak at 1628 cm⁻¹ is attributed to the superposition of stretching vibrations of OH and NH; -1 The strong peak is due to the carboxylate group (-COO). - Antisymmetric stretching vibration, 1000 cm -1 The nearby absorption peak is attributed to the COC stretching vibration of the carboxymethyl chitosan glycocycle backbone. CA is at 2815 cm⁻¹. -1 A Fermi resonance peak for the CH stretching vibration of the aldehyde group appears at 1680, 1630, etc., and characteristic absorptions of conjugated C=O, C=C, and monosubstituted benzene rings are also observed. Compared with pure CMCS, B-CMCS (Mn 2+ 1628 cm⁻¹ in cross-linked blank microcapsules -1 The peak shifted slightly to approximately 1615 cm. -1 Furthermore, the peak shape broadens, and symmetrical stretching peaks (approximately 1400 cm⁻¹) are observed. -1 The strength decreased, while 3443 cm -1 and 1000 cm -1 The peak position and intensity showed no significant change, indicating that Mn 2+ It mainly forms ionic coordination bonds with carboxylate groups, having little impact on the main chain structure of the sugar ring. The cinnamaldehyde sustained-release hydrogel (CMCS-CA) obtained in Example 1, while retaining the characteristic peaks of B-CMCS, showed a peak at 2815 cm⁻¹. -1 (and its companion peak at 2720 cm) -1 The aldehyde group CH double peak was clearly detected, confirming that cinnamaldehyde was successfully loaded; at the same time, 1000 cm⁻¹ -1 The stable peak shape indicates that the sugar ring backbone was not damaged during drug loading. It is noteworthy that the peak shape is stable in the 1640–1660 cm⁻¹ range. -1 No obvious C=N stretching peak was observed in the region, indicating that the aldehyde group of cinnamaldehyde in Example 1 did not undergo a Schiff base reaction with the amino group of CMCS, and that cinnamaldehyde mainly exists in the hydrogel particles in a physically loaded form.

[0053] Test Example 4 Energy Spectrum (EDS) Element Mapping Analysis The cinnamaldehyde sustained-release hydrogel prepared in Example 1 was analyzed by EDS elemental mapping to determine the cinnamaldehyde and Mn content after lyophilization. 2+ Distribution of drug-loaded hydrogel particles.

[0054] The results are as follows Figure 4 As shown, the distribution areas of C, N, and O elements basically overlap and are uniform overall, indicating that carboxymethyl chitosan, as a matrix material, effectively constitutes the continuous skeletal structure of the hydrogel particles; the distribution positions of Mn elements are highly consistent with those of C and O elements, indicating that Mn... 2+ The cinnamaldehyde has undergone coordination crosslinking with the carboxyl and amino groups on the CMCS molecular chain, forming a stable three-dimensional network gel structure. Simultaneously, the sulfur (S) element from the emulsifier Tween 80 overlaps with the carbon (C) element distribution, indicating that the emulsifier is uniformly dispersed in the hydrogel system and plays a good role in emulsifying and stabilizing the loading of cinnamaldehyde. The combined elemental distribution characteristics confirm that the emulsification-ionic crosslinking method can successfully prepare CMCS / Mn loaded with cinnamaldehyde. 2+ In the hydrogel, cinnamaldehyde is mainly physically encapsulated and uniformly distributed within the hydrogel. The overall structure of the hydrogel particles is intact and the component distribution is uniform.

[0055] Test Example 5 ICP test The content of manganese in the lyophilized cinnamaldehyde sustained-release hydrogel prepared in Example 1 was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that the manganese content was 6.23 wt.%.

[0056] Test Example 6 Sustained-release properties The release behavior of the lyophilized cinnamaldehyde sustained-release hydrogel prepared in Example 1 was studied using three phosphate buffer solutions with pH values ​​of 5, 6.5, and 8 as release media. 0.1 g of the prepared hydrogel was placed in a dialysis bag with a molecular weight cutoff of 3500 g / mol, and 2 mL of release medium was added. The bag was tied tightly at both ends and immersed in 200 mL of phosphate buffer solution at room temperature with continuous stirring at 200 rpm. 1.0 mL of release medium was prepared for analysis at set time intervals, and an equal volume of fresh phosphate buffer solution was added to the release system simultaneously. The experiment was repeated twice. Sampling times were set at: 30 min, 1 h, 2 h, 3 h, 5 h, 7 h, 9 h, 12 h, 16 h, 20 h, 24 h, 36 h, 48 h, 60 h, and 72 h. Extraction method of cinnamaldehyde in the release medium: Add ethyl acetate at a volume ratio of 1:2 for aqueous phase and oil phase, i.e., add 2 mL of ethyl acetate, vortex vigorously for 3 min, centrifuge at 5000 rpm for 3 min, take 1.5 mL of supernatant, add 0.5 g of anhydrous sodium sulfate, vortex for 3 min, centrifuge for 3 min, and then filter the supernatant through a membrane for injection.

[0057] Release results as follows Figure 5As shown, the cinnamaldehyde hydrogel particles exhibited sustained-release behavior for over 60 hours in three buffer solutions at pH 5, 6.5, and 8, with no significant burst release in the initial stage. The cumulative release rates after 1 hour were only 2.66%, 1.93%, and 1.61%, respectively, effectively avoiding rapid loss of the active ingredient. The entire release process can be roughly divided into a relatively rapid release period of 0–12 hours and a sustained slow release period of 12–60 hours. The release rate reached 38.57% after 12 hours at pH 5, while it was only 26.83% at pH 8, showing a clear pH dependence. Within a 60-hour release period, both the release rate and the final cumulative release amount followed the order of pH 5 > pH 6.5 > pH 8: the pH 5 group reached its maximum release amount of 67.56% at 36 hours, then fluctuated slightly, reaching 66.98% at 60 hours; the pH 6.5 group had a cumulative release rate of 62.73% over 60 hours; and the pH 8 group had the slowest release, with a plateau period cumulative release rate of only about 53.17%. This pattern suggests that the hydrogel network may contain protonable basic groups. In an acidic environment, protonation causes electrostatic repulsion, leading to swelling and pore expansion of the gel network, thereby accelerating the outward diffusion of cinnamaldehyde. Under alkaline conditions, the groups deprotonate, causing the gel to shrink or form denser physical cross-links, limiting the release of the active ingredient and exhibiting cationic pH response characteristics. All three groups reached the release plateau after 48 hours, indicating that the release of cinnamaldehyde was basically complete. However, the lower final release rate at pH 8 also suggests that some active ingredients are more firmly bound to the gel skeleton in an alkaline environment. Further optimization can be achieved by adjusting the crosslinking density or introducing degradable fragments to improve the completeness of release under different conditions. In summary, Example 1 achieved a sustained-release effect with no obvious burst release, a long duration of action, and significant pH responsiveness, and can regulate the release rate of cinnamaldehyde according to changes in environmental pH.

[0058] Test Example 7 Bird deterrence performance 1. Dose-response detection Test reagent: Cinnamaldehyde sustained-release hydrogel particles obtained by freeze-drying in Example 1.

[0059] Experimental methods: Each birdcage was equipped with 4 food containers. During the feeding period, all 4 food containers were used for feeding to prevent the white-rumped munias from developing a memory for only feeding rice seeds from a particular food container. One water container was placed on each side of the birdcage, and water supply was ensured throughout the feeding period. Cinnamaldehyde slow-release hydrogel particles were used for treatment (3 replicates per treatment).

[0060] Dosage of medicine: Food container area approximately 32 cm² 2 Dosage: 30 g / m 2 60 g / m 2 90 g / m 2 Proceed in sequence.

[0061] Feeding method: Fast for more than 6 hours before the experiment (or fast overnight). Add a certain amount of quartz sand to the feeding box, control the moisture content to 25%, and flatten it. Sprinkle the freeze-dried cinnamaldehyde slow-release hydrogel particles evenly on the surface of the quartz sand. After it has fully absorbed the water (about 30 minutes), sprinkle rice seeds (by number of grains) on the surface of the quartz sand. After feeding for 2 hours, the results are recorded.

[0062] The results are as follows Figure 6 As shown, different dosages of cinnamaldehyde hydrogel exhibited a clear dose-dependent effect on the repellency effect of cinnamaldehyde hydrogel on white-rumped munias. 30 g / m 2 The avoidance rate in the treatment group was 72.85%; when the dosage was increased from 30 g / m²... 2 Increased to 60 g / m 2 At that time, the avoidance rate rose to 82.19%, an increase of 9.34 percentage points; the dosage was further increased from 60 g / m 2 Increase to 90 g / m 2 Afterwards, the avoidance rate reached 93.40%, compared to 60 g / m 2 The treatment improved by 11.21 percentage points. This was compared to two dose escalations (both 30 g / m²). 2 The change in avoidance rate corresponding to the constant increase (of the ablation rate) shows that the increase in avoidance rate in the later stage is slightly higher than that in the earlier stage, suggesting that it is within the range of 30~90 g / m 2 Within the experimental range, the avoidance rate continuously increased with increasing dose, and the marginal effect per unit dose did not decay, maintaining good synergistic potential even at high doses. Based on these results, 90 g / m 2 The treatment achieved a repellency rate of 93.40%, demonstrating an excellent and stable antifeeding effect on white-rumped munias, and can be used as a preferred reference for field application dosage.

[0063] 2. Bird deterrent effectiveness period testing Test reagents: lyophilized cinnamaldehyde sustained-release hydrogel particles and cinnamaldehyde technical grade as described in Example 1.

[0064] Experimental method: The dosage was 90 g / m². 2 .

[0065] Time settings: 0 d, 1 d, 2 d, 3 d, 4 d, 5 d.

[0066] Treatment methods: The hydrogel treatment group and the cinnamaldehyde treatment group were treated directly. The hydrogel treatment group was treated with cinnamaldehyde slow-release hydrogel particles (3 cages), and the cinnamaldehyde treatment group was treated with cinnamaldehyde technical grade (based on the actual amount of gel particles × the drug loading of the gel particles 32.63%, 3 cages), the same below.

[0067] 0d: After adding quartz sand to the feeding box and flattening it, the medicine was evenly placed on the surface of the quartz sand. After about 30 minutes, rice seeds were added for feeding. The results were investigated 2 hours later.

[0068] 1 day: After moistening the feed box with quartz sand, flatten it and evenly place the medicine on the surface of the quartz sand. Place it in a ventilated place for 1 day, and replenish the water with a spray bottle during this period to maintain a constant weight. Then, put rice seeds in for feeding and investigate the results after 2 hours.

[0069] 3d: After adding quartz sand to the feeding box and flattening it, the medicine was evenly placed on the surface of the quartz sand and placed in a ventilated place for 3 days. During this period, water was added with a spray bottle to maintain a constant weight. Then, rice seeds were added for feeding, and the results were investigated after 2 hours.

[0070] 5d: After adding quartz sand to the feeding box and flattening it, the medicine was evenly placed on the surface of the quartz sand and placed in a ventilated place for 5 days. During this period, water was added with a spray bottle to maintain a constant weight. Then, rice seeds were added for feeding, and the results were investigated 2 hours later.

[0071] 7d: After moistening the food box with quartz sand and flattening it, the medicine was evenly placed on the surface of the quartz sand and placed in a ventilated place for 7 days. During this period, water was added with a spray bottle to maintain a constant weight. Rice seeds were then added for feeding, and the results were investigated 2 hours later.

[0072] The results are as follows Figure 7 As shown, the cinnamaldehyde-treated group exhibited a repellency rate as high as 98.48% on the day of application (0 day), demonstrating extremely strong rapid-acting repellency activity. However, its effectiveness was poor, rapidly declining to 69.67% on day 3, 58.21% on day 5, and only 31.78% by day 7. In contrast, the hydrogel-treated group maintained a repellency rate of 95.42% on day 0, comparable to the cinnamaldehyde-treated group; the repellency rates remained at 99.66% and 97.25% on days 1 and 3, respectively, without significant decline; and by days 5 and 7, the repellency rates remained at high levels of 86.37% and 88.79%, respectively, significantly better than the cinnamaldehyde-treated group during the same period. Throughout the 7-day test period, the repellency rate of the hydrogel-treated group remained stable at over 85%, while the cinnamaldehyde-treated group had a shorter duration of effect. This indicates that by regulating the release rate of cinnamaldehyde, the hydrogel effectively overcomes its defects of high volatility and short duration of effect, and achieves a performance transformation from short-acting to long-acting slow-release repellency.

[0073] Example 2 The preparation method is similar to that of the cinnamaldehyde sustained-release hydrogel particles in Example 1, the only difference being that Mn is used instead of cinnamaldehyde. 2+ The solution was replaced with Ca 2+ Ions; among which, Ca 2+ Ca in solution 2+ The concentration is 0.3 mol / L.

[0074] Comparative Example 10 The preparation method is similar to that of the cinnamaldehyde sustained-release hydrogel particles in Example 1, the only difference being that Mn is used instead of cinnamaldehyde. 2+ The solution was replaced with Cu 2+ Ions; of which, Cu 2+ Cu in solution 2+ The concentration is 0.3 mol / L.

[0075] Comparative Example 11 The preparation method is similar to that of the cinnamaldehyde sustained-release hydrogel particles in Example 1, the only difference being that Mn is used instead of cinnamaldehyde. 2+ The solution was replaced with Zn. 2+ Ions; of which, Zn 2+ Zn in solution 2+ The concentration is 0.3 mol / L.

[0076] Test Example 8 1. The cinnamaldehyde sustained-release hydrogels of Example 2, Comparative Examples 10 and 11 were taken respectively, and the drug loading and encapsulation efficiency were tested according to the method of Test Example 1. The results are shown in Table 3.

[0077] Table 3. Results of drug loading and encapsulation efficiency of cinnamaldehyde sustained-release hydrogels in Examples 1-2 and Comparative Examples 10-11

[0078] As can be seen from Table 3, compared to Cu 2+ Ions (Comparative Example 9) and Zn 2+ Ions (Comparative Example 10), Example 1 of the present invention (Mn) 2+ (ion) and Example 2 (Ca) 2+ Ions have a higher drug loading capacity.

[0079] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cinnamaldehyde sustained-release hydrogel particle, characterized in that, The cinnamaldehyde sustained-release hydrogel particles comprise the following raw materials: cinnamaldehyde, carboxymethyl chitosan, water, emulsifier, and metal ion crosslinking agent; The volume-to-mass ratio of cinnamaldehyde to carboxymethyl chitosan is 1 mL: 0.4 g; The volume ratio of cinnamaldehyde to water is 1:10; The concentration of metal ions in the metal ion crosslinking agent is 0.3 mol / L.

2. The cinnamaldehyde sustained-release hydrogel particles according to claim 1, characterized in that, The metal ions include one or more of manganese ions, calcium ions, copper ions, and zinc ions; The volume ratio of cinnamaldehyde to emulsifier is 100:

2.

3. The cinnamaldehyde sustained-release hydrogel particles according to claim 2, characterized in that, The emulsifier includes Tween 80.

4. The method for preparing cinnamaldehyde sustained-release hydrogel particles according to any one of claims 1 to 3, characterized in that, Includes the following steps: Cinnamaldehyde and an emulsifier are mixed to obtain a cinnamaldehyde solution; Mix carboxymethyl chitosan and water to make a carboxymethyl chitosan aqueous solution; The cinnamaldehyde solution and the carboxymethyl chitosan aqueous solution were mixed and emulsified to obtain an O / W emulsion. The O / W emulsion was added dropwise to a metal ion crosslinking agent and cured to obtain the cinnamaldehyde sustained-release hydrogel particles.

5. The preparation method according to claim 4, characterized in that, The emulsification rotation speed is 8000~12000 r / min, and the time is 3~6 min; The curing temperature is 20~30℃ and the time is 3~6 h.

6. The preparation method according to claim 4 or 5, characterized in that, Also includes: The cinnamaldehyde sustained-release hydrogel particles were freeze-dried to obtain freeze-dried cinnamaldehyde sustained-release hydrogel particles.

7. The application of the cinnamaldehyde sustained-release hydrogel particles according to any one of claims 1 to 3 or the cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method according to any one of claims 4 to 6 in bird control.

8. The application according to claim 7, characterized in that, The birds mentioned as pests include the white-rumped munia.

9. A bird repellent, characterized in that, The active ingredient of the bird repellent includes cinnamaldehyde sustained-release hydrogel particles as described in any one of claims 1 to 3 or cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method described in any one of claims 4 to 6.

10. A method for repelling birds from bird damage, characterized in that, The process includes the following steps: applying the cinnamaldehyde sustained-release hydrogel particles according to any one of claims 1 to 3 or the cinnamaldehyde sustained-release hydrogel particles obtained by the preparation method according to any one of claims 4 to 6 to areas where bird damage is frequent; The application amount of the cinnamaldehyde sustained-release hydrogel particles is ≥30 g / m³. 2 .

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