Hyphantria cunea pheromone humidity response electrospun nanofiber and preparation method and lure thereof

Abstract

The invention provides a fall webworm pheromone humidity response electrospinning nanofiber, a preparation method thereof and a lure core, polylactic acid, cellulose nanocrystals and fall webworm pheromone are combined to prepare the nanofiber with the humidity response characteristic, the cellulose nanocrystals (CNCs) serve as a moisture absorption switch, PLA matrix is used for controlled release, and when the humidity reaches a threshold value, the electrostatic spinning nanofiber with the humidity response characteristic is obtained. The expansion of the CNCs initiates the deformation of a PLA phase region, and a pheromone diffusion path is opened. The prepared nanofiber has the advantages of being high in tensile strength, sensitive in humidity response and environmentally friendly, and the problems that when traditional nanofiber loads pheromone, the environmental response is poor, and the release behavior is uncontrollable are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PLA nanofiber and pest invasion prevention and control, and particularly relates to a hygrometric response electrospun nanofiber of an information substance of Hyphantria cunea and a preparation method and a lure core thereof, which provides a new design idea and a feasible scheme for an information substance intelligent slow-release carrier for target pests. BACKGROUND

[0002] Insect pheromones are chemical substances that transmit information between individual insects and have unique advantages in pest control. By extracting or artificially synthesizing the pheromones of target pests, such as sex pheromones and aggregation pheromones, the normal behavior of pests can be interfered with to achieve the purpose of control. For example, sex pheromones can confuse male insects, making them unable to find female insects for mating, thereby reducing the birth rate of pests; aggregation pheromones can attract pests to concentrate, facilitating concentrated trapping. This control method has high specificity, only targeting the target pests, and has little impact on natural enemies and other non-target organisms, can effectively reduce the use of chemical pesticides, reduce environmental pollution and pesticide residue risks, and conforms to the concept of green control. However, insect pheromones are volatile and have poor stability in natural environments, and are greatly affected by environmental factors such as wind direction and temperature, resulting in short effective action time and limited control range, which limits their large-scale application.

[0003] Nanofibers have unique physical and chemical properties, and their combination with insect pheromones can significantly improve the application effect of insect pheromones. Nanofibers have a large specific surface area, which can load more pheromones and increase the content of pheromones in a unit volume. Their porous structure provides a good storage space for pheromones, enabling slow release of pheromones, prolonging the effective action time, and reducing the trouble of frequent application. At the same time, nanofibers can act as a protective barrier to reduce direct contact between pheromones and the external environment, improve their stability, and reduce degradation caused by factors such as light and temperature. In addition, the materials of nanofibers can be designed and controlled according to needs, such as selecting biocompatible and degradable materials to avoid secondary pollution to the environment. Nanofiber membranes prepared by electrospinning and other technologies can be easily applied to different scenarios, such as hanging in the field and placing in pest habitats, improving the flexibility and convenience of control. However, the release mechanism of pheromones loaded by nanofibers still relies on simple diffusion or degradation, which cannot automatically adjust the release rate according to environmental changes, making it difficult to meet the needs of practical applications. SUMMARY

[0004] The application provides a humidity-responsive electrospun nanofiber of a gypsy moth pheromone and a preparation method and a lure core thereof, and the humidity-responsive electrospun nanofiber is prepared from polylactic acid (PLA), cellulose nanocrystals (CNCs) and the gypsy moth pheromone through electrospinning, has high tensile strength, high humidity response sensitivity and environmental friendliness, and solves the problems of poor environmental responsiveness and uncontrollable release behavior of the gypsy moth pheromone when the gypsy moth pheromone is loaded on a traditional nanofiber.

[0005] A first object of the application is to provide a preparation method of a humidity-responsive electrospun nanofiber of a gypsy moth pheromone, which comprises the following steps: adding polylactic acid (PLA) and a gypsy moth pheromone to an organic solvent dispersion liquid of cellulose nanocrystals (CNCs), stirring to form a uniform spinning liquid, and obtaining the humidity-responsive electrospun nanofiber of the gypsy moth pheromone through electrospinning; and the mass ratio of the polylactic acid to the gypsy moth pheromone and the cellulose nanocrystals is (1-5):(1.5-3):(0.01-0.03).

[0006] Preferably, the mass ratio of the polylactic acid to the gypsy moth pheromone and the cellulose nanocrystals is 3:2.34:0.02.

[0007] Preferably, the organic solvent dispersion liquid of the cellulose nanocrystals is prepared by hydrolyzing and purifying microcrystalline cellulose to obtain a cellulose nanocrystal water dispersion liquid, and then dispersing the cellulose nanocrystal water dispersion liquid in an organic solvent.

[0008] Further preferably, the cellulose nanocrystal water dispersion liquid is dispersed in N,N-dimethylformamide, and the mass-volume ratio of the cellulose nanocrystals to N,N-dimethylformamide is 0.001-0.003 g / mL.

[0009] Preferably, the electrospinning is performed under the following conditions: a flow rate of 1-3 ml / h, a distance between a syringe needle and a receiving device of 8-12 cm, and a high-voltage power supply voltage of 10-23 kv.

[0010] Preferably, the electrospinning is performed by the following steps: injecting the spinning liquid into a syringe pump, and then connecting a power supply to perform electrospinning, wherein the flow rate is 1-3 ml / h, further 2 ml / h, the distance between the syringe needle and the receiving device is adjusted to 8-12 cm, further 10 cm, the high-voltage power supply voltage is 10-23 kv, further 15 kv, the temperature of the receiving device is set to 35 DEG C, and the rotating speed of a roller is 500 r / min; after the electrospinning, a uniform white film is collected on a hand screen roller, and vacuum drying is performed at room temperature to obtain the humidity-responsive electrospun nanofiber of the gypsy moth pheromone.

[0011] Preferably, the American white moth pheromone is a mixture of (9Z, 12Z)-octadecadienal, (9Z, 12Z, 15Z)-octadecatrienal, (3Z, 6Z, 9S, 10R)-9, 10-epoxy-3, 6-heneicosadiene and (3Z, 6Z, 9S, 10R)-9, 10-epoxy-1, 3, 6-heneicosatriene. Further, the weight ratio of (9Z, 12Z)-octadecadienal, (9Z, 12Z, 15Z)-octadecatrienal, (3Z, 6Z, 9S, 10R)-9, 10-epoxy-3, 6-heneicosadiene and (3Z, 6Z, 9S, 10R)-9, 10-epoxy-1, 3, 6-heneicosatriene is 2:33.6:58.4:6.

[0012] A second object of the present application is to provide the American white moth pheromone humidity-responsive electrospun nanofiber prepared by the above preparation method.

[0013] A third object of the present application is to provide an American white moth attracting core, which is the above American white moth pheromone humidity-responsive electrospun nanofiber as the attracting core.

[0014] Preferably, the size of the attracting core is that the American white moth pheromone humidity-responsive electrospun nanofiber is cut into a 1cm x 5cm attracting core sheet. The attracting core sheet is used for American white moth sex pheromone trapping control, cooperates with a barrel-shaped or boat-shaped moth attracting device, and achieves the purposes of intelligent slow release and targeted pest control.

[0015] A fourth object of the present application is to provide the application of the above American white moth pheromone humidity-responsive electrospun nanofiber in the prevention and control of American white moths.

[0016] Polylactic acid (PLA) is a biodegradable polymer material, which has good biocompatibility and environmental friendliness, avoids carrier residue pollution, and meets the ecological prevention and control concept. Cellulose nanocrystals (CNCs) have high strength, high modulus and unique nanoscale size effect, and are sensitive to humidity. Under different humidity environments, the moisture absorption and expansion or contraction of CNCs will cause changes in the structure of nanofibers, thereby regulating the release rate of pheromones. When the environmental humidity is high, the CNCs absorb moisture and expand, the fiber pore increases, and the release rate of pheromones accelerates; when the humidity decreases, the CNCs shrink, the fiber structure is compact, and the release rate of pheromones slows down. This humidity response characteristic enables the carrier to automatically adjust the release of pheromones according to the changes in environmental humidity, better adapts to the fluctuations in humidity in the natural environment, and improves the utilization efficiency of pheromones. The present application combines polylactic acid, cellulose nanocrystals and pheromones to prepare nanofibers, forming an intelligent slow-release carrier with humidity response characteristics.

[0017] The present application has the following beneficial effects:

[0018] 1.The humidity-responsive electrospun nanofiber of the invention has humidity-responsive controlled release function, and cellulose nanocrystals (CNCs) are used as humidity switchers, and the hydroxyl groups (-OH) on the surface of the humidity switchers combine with water molecules to expand and form nanochannels in a high-humidity environment (RH>80%); and PLA is used as the matrix for controlled release, and the CNCs are directionally distributed in the PLA phase to form a "humidity sensing domain"; when the humidity reaches the threshold value (RH≥75%) of the peak activity of the American white moth at night, the CNCs expand to cause the deformation of the PLA phase, and the diffusion path of the pheromone is opened.

[0019] 2.The humidity-responsive electrospun nanofiber of the invention has stable structure and high tensile strength, and CNCs are used as nanoreinforcers to prevent the structure from collapsing in a high-humidity environment.

[0020] 3.The humidity-responsive electrospun nanofiber of the invention can carry a certain amount of pheromone volatiles to complete release, and is self-degradable in the field / forest, which is intelligent, efficient, and environmentally friendly.

[0021] 4.The preparation process of the humidity-responsive electrospun nanofiber of the invention is stable, short in cycle, easy to control, and strong in operability. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The scanning electron microscope (SEM) image of the PLA nanofiber prepared in Example 1.

[0023] Figure 2 The diameter distribution graph of the PLA nanofiber prepared in Example 1.

[0024] Figure 3 The contact angle graph of the PLA nanofiber prepared in Example 1.

[0025] Figure 4 The ultraviolet-visible absorption spectrum graph of the PLA nanofiber prepared in Example 1 and the nanofiber (PLA+CNCs) prepared in Comparative Example 1.

[0026] Figure 5 The infrared spectrum graph of the PLA nanofiber prepared in Example 1.

[0027] Figure 6 The GC-MS humidity control effect graph of the PLA nanofiber prepared in Example 1 and the nanofiber (PLA-SP) prepared in Comparative Example 2. DETAILED DESCRIPTION

[0028] The following examples are further illustrations of the invention, but not limitations thereof.

[0029] Example 1 Preparation of the humidity-responsive electrospun nanofiber of the American white moth pheromone

[0030] The electrospun nanofiber of the humidity response of the information of the American white moth in the Guangdong Provincial Academy of Animal Sciences in January 2025 was prepared, and the specific steps were as follows:

[0031] 1) Refer to the method in the literature (Huang Siqi, Cheng Wanli, Bailong, et al. Preparation of polystyrene / nanocellulose crystal nanocomposite film by electrospinning and its performance characterization [J]. Polymer materials science and engineering, 2016, 32(03): 141-146. DOI:10.16865 / j.cnki.1000-7555.2016.03.026.) to prepare cellulose nanocrystal (CNCs) aqueous dispersion: 40g MCC (microcrystalline cellulose, KY100S) was mixed with 170g 64% sulfuric acid solution in a flask, and continuous rapid stirring was carried out in a 45℃ water bath for 1h, until the solution was light yellow, deionized water was added to dilute the reactants to terminate the reaction, and the obtained solution was placed in a 4℃ environment for 24h, after standing, the settled CNCs were collected, and after repeated resuspension-centrifugation, a turbid liquid was obtained, which was placed in a dialysis bag and dialyzed to pH 7, to obtain cellulose nanocrystal aqueous dispersion (concentration 1% w / v).

[0032] 2) Take 2ml of the cellulose nanocrystal aqueous dispersion prepared in step 1) and disperse it in 10ml N,N-dimethylformamide, add 3g polylactic acid (Mn=110000) and 2.34g information compound, the information compound is composed of (9Z,12Z)-octadecadienal, (9Z,12Z,15Z)-octadecatrienal, (3Z,6Z,9S,10R)-9,10-epoxy-3,6-eicosadiene and (3Z,6Z,9S,10R)-9,10-epoxy-1,3,6-eicosatriene, and the weight ratio is 2:33.6:58.4:6, stir in a 20ml beaker at 500r / min overnight to obtain an electrospinning solution.

[0033] 3) Adjust the parameters of the electrospinning instrument, adjust the distance between the needle and the collection barrel to 10cm, the humidity in the instrument is 40%, the temperature is 35℃, and the shape of the spinning port needle is round; take 12ml of the electrospinning solution prepared in step 2) and inject it into the syringe installed on the 20ml syringe pump, connect the power supply to electrospin, the flow rate is 2ml / h, adjust the distance between the syringe needle and the receiving device to 10cm, the voltage of the high-voltage power supply is 15kv, and the temperature of the receiving device is set to 35℃, the rotating speed of the drum is 500r / min;

[0034] 4) Under the high voltage of 15kv, the solution is converted into a charged jet stream, which is deposited on the surface of the substrate, and the polymer in the jet stream is solidified to form a white nanofiber film. After vacuum drying at room temperature, the wetness response electrospun nanofiber of the American white moth pheromone (hereinafter referred to as PLA nanofiber) is obtained, with a size of about 30cm x 40cm.

[0035] Comparative Example 1

[0036] Reference Example 1, except that no pheromone compound is added in step 2), and the electrospinning solution contains cellulose nanocrystals and polylactic acid, and the other steps are the same as Example 1, to prepare the nanofiber (PLA+CNCs).

[0037] Comparative Example 2

[0038] Reference Example 1, except that no cellulose nanocrystal aqueous dispersion is added, and the electrospinning solution contains polylactic acid and pheromone compound, and the other steps are the same as Example 1, to prepare the nanofiber (PLA-SP).

[0039] Example 2 Nanofiber Characterization

[0040] The PLA nanofiber prepared in Example 1 is characterized by scanning electron microscopy, contact angle test, infrared spectrum test, and ultraviolet-visible absorption spectrum test; and the nanofiber (PLA+CNCs) prepared in Comparative Example 1 is tested by ultraviolet-visible absorption spectrum.

[0041] The scanning electron micrograph of the PLA nanofiber is shown in Figure 1 . The scanning electron micrograph clearly shows the uniform distribution of the PLA nanofiber in a network structure, with good visual consistency and integrity. Through scanning electron microscopy measurement, it can be observed that the diameter of the PLA nanofiber is between 119.089±23.624nm, and the fiber diameter distribution is relatively uniform. The fiber in the electron micrograph is continuous without beads or fractures, and is interwoven into a network structure. The balance between fluid stretching and solidification in the spinning process is stable, and the dispersion of CNCs is excellent, which ensures the uniformity of the composite system. From the compatibility of the composite system, PLA (degradable polymer) and CNCs (reinforcing phase) are blended and spun, and the process needs to consider the compatibility of the two. The continuous morphology of the fiber proves that the interface bonding is good.

[0042] The diameter distribution graph of the PLA nanofiber is shown in Figure 2 . The diameter of the PLA nanofiber is mainly distributed in

[0043] 119.089±23.624nm, with a diameter of hundreds of nanometers and low dispersion, which gives a high specific surface area and greatly improves the loading capacity of the American white moth pheromone; at the same time, the uniform fiber diameter makes the pheromone distribute more uniformly in the fiber, avoiding fluctuations in the release rate and ensuring stable and controllable trapping effect.

[0044] The contact angle of PLA nanofiber is shown in Figure 3 The contact angle figure intuitively shows the high hydrophobicity of PLA nanofiber prepared by electrospinning technology. The contact angle of the material is 135°, and the low surface wettability endows self-cleaning, anti-fouling, and water permeation resistance; combined with the biodegradability of PLA and the mechanical enhancement of CNCs, the function is more composite.

[0045] The visible absorption spectrum of PLA nanofiber and the nanofiber prepared in Comparative Example 1 (PLA+CNCs) is shown in Figure 4 The pheromone is a kind of chemical substance that is easy to be photodegraded, and the visible light radiation will affect its utility. In the wavelength range of 400-1000 nm, the thin film prepared by electrospinning has a transmittance of less than 16%, which can shield the penetration of ultraviolet radiation and prevent the pheromone from being directly exposed to ultraviolet light, and can simultaneously weaken the ultraviolet degradation and visible light-induced slow oxidation, so that the nanofiber can continuously and stably release the pheromone in the field, reduce the maintenance frequency of the trapping device, and improve the economy of green prevention and control.

[0046] The infrared spectrum of PLA nanofiber is shown in Figure 5 The peaks at 2978 cm-1 and 2854 cm-1 in mark A correspond to the stretching vibration of C-H in the pheromone compound of American white moth, the peak at 1721 cm-1 in mark B corresponds to the stretching vibration of C=O in the pheromone compound of American white moth, the peaks at 850-880 cm-1 in mark C correspond to the stretching vibration of C-O-C in the pheromone compound of American white moth, and the peak at 1690 cm-1 in mark D corresponds to the stretching vibration of C-C in the pheromone compound of American white moth.

[0047] In summary, the above results can prove that the pheromone of American white moth and PLA have been well combined by electrospinning.

[0048] Example 3 Humidity response experiment of nanofiber

[0049] On February 25, 2025, the PLA nanofiber prepared in Example 1 and the nanofiber prepared in Comparative Example 2 (PLA-SP) were subjected to humidity response experiment. A humidity of 90% was taken, and the pheromone was extracted after 0, 4, 6, and 8 hours to detect the pheromone content in the nanofiber by gas chromatography-mass spectrometry to verify the effect of using CNCs to achieve humidity response.

[0050] The specific experimental scheme is as follows:

[0051] 1) Two kinds of nanofibers were cut into 1x5 cm size and placed in 90% relative humidity. Samples were collected at 0, 4, 6, and 8 hours, respectively. Three parallel samples were prepared for each group;

[0052] 2) After sampling, n-hexane was used as the extraction solvent to extract the nanofiber-loaded American white moth pheromone at 35°C on a shaking table;

[0053] After centrifugation, filtration, and extraction, the residual amount of pheromone was quantitatively analyzed by gas chromatography-mass spectrometry. The chromatography-mass spectrometry parameters were as follows: detection platform Agilent 7890B / 5977BMSD, chromatography column type HP-5MS, Hp-5ms 30m, injection port temperature 260°C, carrier gas helium, chromatography column flow 1 mL / min, injection port pressure 7.06991, carrier gas flow 34 mL / min, septum purge flow 3 mL / min, purge mode: standard, splitless injection, split outlet purge flow 100 ml / min, 0.75 min, carrier gas saving started at 4 min. MS: EI ion source, voltage 70ev. The temperature program was as follows:

[0054]

[0055] Experimental results:

[0056] The humidity response effect of the two kinds of nanofibers is shown in Figure 6 (PLA-CNCs-SP in the figure is the result of PLA nanofiber prepared in Example 1).

[0057] The control group PLA-SP (gray): the pheromone content is stable after 0 hours, and it increases as a whole from 4 to 8 hours, indicating that the water absorption of the PLA carrier under high humidity causes the enrichment or release of pheromone to be hindered, hindering the diffusion of pheromone, causing the pheromone to be retained, and even reverse enrichment, and release out of control (one-way ANOVA, F 3,12 = 1.376, P = 0.2972, the same lowercase letter indicates that there is no significant difference between groups). PLA-CNCs-SP (blue): the baseline at 0 hours, the pheromone content significantly decreases after 4 hours, and it still maintains a low level at 8 hours (one-way ANOVA and Tukey multiple comparison, F 3,48 = 26.49, P < 0.0001, different lowercase letters indicate significant differences between groups). The core of the humidity response mechanism of CNCs is that CNCs absorb water and swell under high humidity, opening the pores of the PLA fiber and actively triggering the accelerated release of pheromone to avoid degradation or failure of the pheromone due to retention in the high humidity environment.

[0058] In the field of high humidity (such as night, rainy), the PLA nanofiber prepared by example 1 realizes "CNCs swelling → fiber structure opening → pheromone on-demand release", which not only solves the "lock medicine" problem of PLA matrix under high humidity, but also realizes the dynamic regulation of "low humidity stable storage and high humidity fast release", matches the humidity fluctuation of American white moth during the emergence period (active male moths after rain and at night, synchronous release of pheromones to enhance trapping), and improves the timeliness and accuracy of green prevention and control.

Claims

1. A method for preparing humidity-responsive electrospun nanofibers based on the pheromone of the American white moth, characterized in that, Includes the following steps: Polylactic acid and fall webworm pheromone were added to an organic solvent dispersion of cellulose nanocrystals and stirred to form a uniform spinning solution. Fall webworm pheromone humidity-responsive electrospun nanofibers were obtained by electrospinning. The mass ratio of polylactic acid to fall webworm pheromone and cellulose nanocrystals was (1-5):(1.5-3):(0.01-0.03).

2. The method according to claim 1, characterized in that, The mass ratio of polylactic acid to American white moth pheromone and cellulose nanocrystals was 3:2.34:0.

02.

3. The method according to claim 1, characterized in that, The organic solvent dispersion of the cellulose nanocrystals is obtained by hydrolyzing and purifying microcrystalline cellulose with sulfuric acid to obtain an aqueous dispersion of cellulose nanocrystals, which is then dispersed in an organic solvent.

4. The method according to claim 3, characterized in that, Cellulose nanocrystals were dispersed in an aqueous dispersion in N,N-dimethylformamide, with a mass-to-volume ratio of cellulose nanocrystals to N,N-dimethylformamide of 0.001–0.003 g / mL.

5. The method according to claim 1, characterized in that, The conditions for electrospinning are: flow rate 1-3 ml / h, distance from syringe needle to receiving device 8-12 cm, and high voltage power supply voltage 10-23 kV.

6. The method according to claim 1, characterized in that, The pheromone of the American white moth is a mixture of (9Z, 12Z)-octadecadienal, (9Z, 12Z, 15Z)-octadectrienal, (3Z, 6Z, 9S, 10R)-9,10-epoxy-3,6-tetradecadiene and (3Z, 6Z, 9S, 10R)-9,10-epoxy-1,3,6-tetradectriene.

7. The pheromone humidity-responsive electrospun nanofibers of the American white moth prepared by the method of any one of claims 1-6.

8. A lure for attracting the fall webworm, characterized in that, The American white moth pheromone humidity-responsive electrospun nanofiber as described in claim 7 is used as the lure core.

9. The lure core according to claim 8, characterized in that, The lure core is sized by cutting the humidity-responsive electrospun nanofibers of the American white moth pheromone into 1cm x 5cm lure cores.

10. The application of the humidity-responsive electrospun nanofibers of the American white moth pheromone as described in claim 7 in the control of the American white moth.

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