Phytosterol Pickering emulsion based on nanofiber as well as preparation method and application of phytosterol Pickering emulsion

Abstract

The invention discloses a nanometer fiber yarn-based phytosterol Pickering emulsion as well as a preparation method and application thereof, and the nanometer fiber yarn-based phytosterol Pickering emulsion comprises the following components in parts by weight: 0.5-1 part of nanometer fiber yarn; 1 to 10 parts of phytosterol / phytosterol ester; 95 to 105 parts of a water phase component; 95 to 105 parts of an oil phase component; the nanofibers are extracted from agricultural wastes; according to the invention, the nanofiber is used as the only or main stabilizer of the phytosterol Pickering emulsion, so that the problems of solubility, emulsion stability and bioaccessibility of phytosterol can be solved at the same time; and efficient interface stability and steric hindrance stability are realized by utilizing a unique nano network structure of the nano fiber yarns, and a natural, safe and efficient phytosterol delivery system is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of emulsion preparation, in particular to a phytosterol Pickering emulsion based on nanofibers and a preparation method and application thereof. BACKGROUND

[0002] Phytosterols are important plant secondary metabolites, which have been proven to have the effects of regulating plant growth and enhancing crop stress resistance (such as drought resistance, salt resistance, disease resistance, etc.), and have great application potential in green agriculture. However, its inherent strong hydrophobicity (insoluble in water, and limited solubility in oil) seriously limits its application in actual agricultural production. The traditional solution is usually to prepare it into emulsifiable concentrate, wettable powder or water dispersible granule and other dosage forms.

[0003] In the prior art, attempts to prepare phytosterols into emulsions are a common strategy to improve their bioavailability. Synthetic surfactants (such as Tween, Span series) or high molecular emulsifiers are usually used for emulsification. Some natural emulsifiers or particles (such as modified starch, protein, silicon dioxide nanoparticles, etc.) have also been explored to stabilize the emulsion. SUMMARY

[0004] To solve the above technical problems, the present application provides a phytosterol Pickering emulsion based on nanofibers and a preparation method and application thereof.

[0005] The technical scheme of the present application is: a phytosterol Pickering emulsion based on nanofibers, comprising the following components in terms of weight fraction: 0.5-1 parts of nanofibers; 1-10 parts of phytosterols / phytosterol esters; 95-105 parts of water phase components; 95-105 parts of oil phase components; The nanofibers are extracted from agricultural waste, and the agricultural waste is any one or more of corn straw, citrus peel and sugarcane residue; the phytosterols are β-sitosterol, stigmasterol, brassicasterol, campesterol or a mixture composed of any 2-4 kinds thereof in any ratio; the phytosterol esters are esters prepared from phytosterols and fatty acids in a ratio of 1:1.1-1.4, and the fatty acids are any one or a mixture of 2-3 kinds thereof in any ratio.

[0006] Further, the preparation method of the nanofibers is: (1) Pretreatment of agricultural waste First, the agricultural waste is hot air dried at 55-65 ℃ to a constant weight, and the dried agricultural waste is crushed to 40-80 mesh; (2) Steam explosion The pulverized agricultural waste is then loaded into a sealed reaction kettle, and an ethanol-water solution is added at a ratio of 1-3 g: 10 mL, and maintained at 170-180 °C, 1.0-1.2 MPa for 5-7 min, and then depressurized and flash exploded; (3) Alkaline treatment The modified pulp is obtained by soaking in an alkaline solution of 5-10 wt% at 70-90 °C for 4-8 h, and then bleaching with an oxidant of 0.8-1.2 wt% at 25-30 °C for 25-30 min; the alkaline solution is sodium hydroxide or potassium hydroxide; and the oxidant is NaClO2 or H2O2; (4) Post-treatment The modified pulp is passed through a microfluidizer at 550-650 bar for 2-4 times, and then sent to a microwave-ultrasonic reaction chamber with a microwave power of 300-500 W, an ultrasonic power of 20-25 Hz, and a pulse of 5 s / 5 s for 10-20 min, and finally terminated by adding 8-10 times the volume of deionized water, and centrifuged at 8000-10000 r / min to obtain a milky white suspension, which is recorded as a nanocellulose suspension; then loaded into a dialysis bag and dialyzed with deionized water for 3-5 days until the pH is neutral, and then 0.03-0.05 wt% chitosan oligosaccharide is added to the dialyzed suspension, and centrifuged at 20-30 °C and 9000-10000 r / min to obtain nanocellulose fibers; Description: The pulverization treatment can increase the specific surface area of the agricultural waste, which is more conducive to subsequent reactions. The steam explosion stage can hydrolyze the acetyl groups in hemicellulose to produce acetic acid, making the environment acidic, and allowing the hemicellulose to continue to hydrolyze. Then, the pressure is instantaneously released to atmospheric pressure, and the liquid water in the cell wall is instantaneously vaporized and expanded, physically tearing the fiber structure in the waste, greatly increasing the specific surface area, and greatly increasing the phytosterol loading capacity. Alkaline treatment and bleaching can increase the lignin removal rate to 92%, and retain more than 90% of the crystallinity of cellulose (type I), which retains the mechanical strength for subsequent high-substitution degree modification. Chitosan oligosaccharide is positively charged (ζ ≈ +35 mV), which can form a 20-30 nm thick coating with negatively charged CNF, significantly improving the leaf adhesion rate. Chitosan oligosaccharide itself can induce crop system resistance (ISR), and synergize with phytosterols to increase the survival rate of crop seedlings under salt stress.

[0007] Further, the aqueous phase component is any one of deionized water and a water solution containing a pH adjuster or a preservative; the pH adjuster is a 18-20 wt% sodium hydroxide solution, which can adjust the pH of the system to 7.0-10.0; and the preservative is potassium sorbate or microorganism E, and the addition amount is 0.01-0.1 wt%; Note: A small amount of auxiliary agent can play a role in stabilizing the emulsion, protecting sterols, promoting crop absorption, and being friendly to field use. The addition of a preservative can be used to assist in film formation.

[0008] Further, the oil phase component is any one of soybean oil, sunflower oil, and rapeseed oil; Note: The above ingredients are widely available, easy to obtain, and green and safe, making them excellent carriers for phytosterols / phytosterol esters.

[0009] The present application also provides a method for preparing a phytosterol Pickering emulsion based on nanofibers, comprising the following steps: S1, Preparation of a nanofiber dispersion The nanofibers are dispersed in the water phase at a weight ratio of nanofibers to water of 1:1-20, and are subjected to homogenization treatment using a microjet homogenizer at a first-stage pressure of 500-600 bar and a second-stage pressure of 50-60 bar, with 10-15 cycles, to obtain a nanofiber dispersion; S2, Preparation of a sterol-containing oil phase The phytosterol / phytosterol ester is dissolved in the oil phase component at a weight ratio of 1:5-10, and is heated to 40-65°C with stirring to obtain a sterol-containing oil phase; S3, Emulsion preparation The sterol-containing oil phase is added to the nanofiber dispersion at a drop rate of not more than 90-100 g / min under the condition of a rotation speed of 400-800 rpm, to prepare a coarse emulsion; then the coarse emulsion is subjected to high-pressure homogenization treatment at a pressure of 30-60 MPa for 2-4 times, to obtain an O / W type phytosterol Pickering emulsion based on nanofibers, which is stable and loaded with phytosterol / phytosterol ester; Note: PNFs form a dense nanometer network in the water phase, physically embedding and restricting the crystallites, oil droplets, or molecular aggregates of phytosterol (especially phytosterol ester with stronger hydrophobicity) in the network voids; when the composite exists in the form of an emulsion, PNFs can effectively adsorb on the interface of the oil droplets formed by phytosterol / phytosterol ester, forming a stable Pickering emulsion structure; the presence of phytosterol ester can further optimize the interfacial properties of the oil droplets and promote the adsorption of PNFs; this composite material is not a simple mixture, but a stable structure in which PNFs form a continuous phase and phytosterol / phytosterol ester is dispersed therein in a physically embedded and / or interfacially stabilized form; this structure endows the material with unique drought resistance; the above method can be used to prepare a stable, milky-white phytosterol Pickering emulsion, which has excellent physical stability (does not separate over a long period of storage), chemical stability (protects sterols), and dilution stability (is suitable for field spraying and dilution).

[0010] S2 and S3 are not limited to the one provided in this application. They can also be to directly disperse phytosterols / phytosterol esters in a PNF dispersion at a weight ratio of 1~10:100~200 (or to disperse phytosterols, phytosterol esters, and PNF dispersions at a weight ratio of 1~5:1~10:100~200), and then treat them with microfluidic flow 2~4 times at a temperature of 20~40℃ and a pressure of 100~150Mpa. The hydrophobic sterols / sterol esters are dispersed into micron-sized particles or aggregates by mechanical force and forcibly dispersed and embedded into the three-dimensional network structure of PNFs to obtain a hydrogel / dispersion with high solid content.

[0011] Furthermore, the phytosterol pickerine emulsion based on nanofibers obtained in S3 was further processed into powder form. The powdering process is as follows: spray drying is carried out under the following conditions: the temperature inside the spray drying tower is controlled at 80~120℃, the air inlet temperature is 100~160℃, and the vacuum degree inside the tower is -0.8~1.0Mpa to obtain powder. Note: Materials processed into powder form are easier to store and transport.

[0012] Furthermore, the phytosterol pickerine emulsion based on nanofibers obtained in S3 was further processed into powder form. The powdering process is as follows: the above-mentioned O / W type Pickering emulsion is placed in a freeze dryer, the vacuum degree is controlled to be below 10pa, the material is pre-cooled to -80℃~-60℃, and then the heating rate is controlled to be 5~10℃ / h, the temperature is gradually increased to 20℃ and held for 4~6h to obtain the dried product, which is then pulverized to obtain the powder product. Note: Materials processed into powder form are easier to store and transport.

[0013] This invention also provides the application of phytosterol pickering emulsion based on nanofibers in the preparation of agricultural formulations that enhance crop stress resistance.

[0014] Furthermore, the application method is as follows: As a foliar spray or root treatment / irrigation agent: dilute the plant sterol pickering emulsion to 500-3000 times and apply it, then spray it on the crop leaves at 450-600 L / ha, or irrigate the roots at 3-5 L / plant. Or as a soil amendment / slow-release material: Apply in the form of dry powder or emulsion, for every square meter of topsoil, apply 1~10g of dry powder; apply 20~30g of emulsion. Note: The emulsion prepared in this application can be directly diluted and used for foliar spraying or root irrigation of crops, which significantly improves the attachment, absorption and utilization efficiency of phytosterols on crops, and plays a role in stress resistance and yield increase.

[0015] The beneficial effects of this invention are: (1) This invention uses nanofibers as the sole or main stabilizer for phytosterol Pickering emulsions; it can simultaneously solve the problems of phytosterol solubility, emulsion stability and bioavailability; and it can achieve efficient interface stability and steric hindrance stability by utilizing the unique nano-network structure of nanofibers; thus providing a natural, safe and efficient phytosterol delivery system.

[0016] (2) The nanocellulose prepared by the present invention solves the problems of difficult and unstable sterol absorption through three-dimensional network confinement and biomimetic sugar chain modification; it achieves efficient and green preparation by microwave-ultrasound process; by adding chitosan oligosaccharide, it forms a thick coating with negatively charged CNF, which significantly improves the leaf adhesion rate; at the same time, chitosan oligosaccharide itself can induce crop system resistance and synergistically enhance the effect with phytosterol, thereby improving the survival rate of crop seedlings under salt stress. Attached Figure Description

[0017] Figure 1 This is an appearance image of the phytosterol pickerling emulsion prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the phytosterol pickerine emulsion prepared in Example 1 of this invention; Figure 3 This is a particle size analysis diagram of the phytosterol pickering emulsion prepared in Example 1 of the present invention; Figure 4 This is a diagram showing the effect of the phytosterol pickering emulsion prepared in Example 1 of the present invention on corn seedling emergence under drought stress. Detailed Implementation

[0018] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0019] Example 1: A phytosterol pickering emulsion based on nanofibers, comprising the following components by weight: 0.7 parts of nanofiber filaments; 10 parts of phytosterols; 100 parts of aqueous phase component; 100 parts of oil phase component; The nanofibers were extracted from corn stalks; the plant sterol was β-sitosterol; the plant sterol ester was prepared by mixing plant sterol and oleic acid in a weight ratio of 1:1.3; the aqueous phase consisted of deionized water and 0.05 wt% potassium sorbate; the oil phase was soybean oil. The preparation method of nanofiber filaments is as follows: (1) Agricultural waste pretreatment: First, the agricultural waste of corn stalks is dried with hot air at 60℃ to constant weight, and the dried agricultural waste is crushed to 40~80 mesh; (2) Steam explosion: Then the crushed agricultural waste is loaded into a closed reaction vessel, and ethanol-water solution is added at a ratio of 2g:10mL. The pressure is released and the vessel is maintained at 175℃ and 1.1MPa for 6min; (3) Alkali treatment: 8wt% alkali solution is used to soak the filaments at 80℃ for 6h, and then 1.0wt% oxidant is used to bleach the filaments at 28℃ for 28min to obtain the modified slurry; the alkali solution is sodium hydroxide; the oxidant is Na ClO2; (4) Post-treatment: The modified slurry was passed through a microfluidic homogenizer at 600 bar three times, and then sent to a microwave-ultrasonic reaction chamber with a microwave power of 400W, an ultrasonic power of 23Hz, and a pulse of 5s / 5s for 15min. Finally, 9 times the volume of deionized water was added to terminate the reaction. The mixture was centrifuged at 9000r / min to obtain a milky white suspension, which was recorded as nanocellulose suspension. Then it was put into a dialysis bag and dialyzed with deionized water for 4 days until the pH was neutral. Then 0.04wt% chitosan was added to the dialysis suspension and centrifuged at 25℃ and 9500r / min to concentrate the nanofibers. The preparation method of phytosterol pickerine emulsion based on nanofibers includes the following steps: S1, Preparation of Nanofiber Dispersion The nanofibers were dispersed in an aqueous phase at a weight ratio of 1:10 to water. The nanofibers were then homogenized using a microfluidic homogenizer at a first-stage pressure of 550 bar and a second-stage pressure of 55 bar, and the process was repeated 13 times to obtain the nanofiber dispersion. S2, Preparation of sterol-containing oil phase Phytosterols / phytosterol esters were dissolved in the oil phase component at a weight ratio of 1:8, and the mixture was heated to 55°C and stirred to obtain an oil phase containing sterols. S3, Emulsion Preparation The sterol-containing oil phase was dispersed at 600 rpm for 3 min, and then added to the nanofiber aqueous dispersion at a dropping rate of 80 g / min to obtain a crude emulsion. The crude emulsion was then subjected to high-pressure homogenization at 45 MPa for 3 cycles to obtain a PNFs-stable, O / W-type phytosterol-pickerlin emulsion based on nanofibers and loaded with phytosterols / sterol esters. The phytosterol-pickerlin emulsion based on nanofibers obtained in step S3 was then powdered. The powdering process is as follows: spray drying is carried out under the following conditions: the temperature inside the spray drying tower is controlled at 100℃, the inlet air temperature is 130℃, and the vacuum degree inside the tower is 0.2Mpa to obtain powder. It can be applied in the preparation of agricultural formulations that enhance crop stress resistance; Application method: as a foliar spray or root treatment / irrigation agent: dilute the phytosterol Pickering emulsion to 1000 times, then spray it on the crop leaves at 520 L / ha, or irrigate the roots at 4 L / plant.

[0020] Example 2: Unlike Example 1, the phytosterol pickerling emulsion based on nanofibers comprises the following components by weight: 0.5 parts of nanofiber filaments; 1 part of phytosterols / phytosterol esters; 95 parts of aqueous phase component; 95 parts of oil phase component.

[0021] Example 3: Unlike Example 1, the phytosterol pickerling emulsion based on nanofibers comprises the following components by weight: One part of nanofiber filament; 10 parts of phytosterols / phytosterol esters; 105 parts of aqueous phase component; 105 parts of oil phase component.

[0022] Example 4: Unlike Example 1, the nanofibers were obtained from citrus peel.

[0023] Example 5: Unlike Example 1, the nanofibers were obtained from sugarcane bagasse.

[0024] Example 6: Unlike Example 1, the plant phytosterol is stigmasterol.

[0025] Example 7: Unlike Example 1, the plant phytosterol is campesterol.

[0026] Example 8: Unlike Example 1, in the preparation method of nanofibers, agricultural waste is first dried with hot air at 55°C to constant weight, and the dried agricultural waste is crushed to 40-80 mesh; then the crushed agricultural waste is loaded into a closed reaction vessel, and an ethanol-water solution is added at a ratio of 1g:10mL, and the reaction is maintained at 170°C and 1.0MPa for 5min, followed by pressure release and flash explosion.

[0027] Example 9: Unlike Example 1, in the preparation method of nanofibers, agricultural waste is first dried with hot air at 65°C to constant weight, and the dried agricultural waste is crushed to 40-80 mesh; then the crushed agricultural waste is loaded into a closed reaction vessel, and ethanol-water solution is added at a ratio of 3g:10mL. The reaction vessel is maintained at 180°C and 1.2MPa for 7min, and then depressurized and flashed.

[0028] Example 10: Unlike Example 1, in the preparation method of nanofibers, a 5wt% alkaline solution was used to soak the nanofibers at 70°C for 4 hours, and then bleached them at 25°C for 25 minutes with a 0.8wt% oxidant to obtain a modified slurry.

[0029] Example 11: Unlike Example 1, in the preparation method of nanofibers, a 10wt% alkaline solution was used to soak the nanofibers at 90°C for 8 hours, and then bleached them at 30°C for 30 minutes with a 1.2wt% oxidant to obtain a modified slurry; the alkaline solution was potassium hydroxide; and the oxidant was H2O2.

[0030] Example 12: Unlike Example 1, in the preparation method of nanofibers, the above modified slurry was passed through a microfluidic homogenizer at 550 bar twice, and then sent to a microwave-ultrasonic reaction chamber with microwave power of 300W, ultrasonic power of 20Hz, and pulse of 5s / 5s for 10min. Finally, 8 times the volume of deionized water was added to terminate the reaction, and the mixture was centrifuged at 8000r / min to obtain a milky white suspension, which was denoted as nanocellulose suspension.

[0031] Example 13: Unlike Example 1, in the preparation method of nanofibers, the above modified slurry was passed through a microfluidic homogenizer at 650 bar four times, and then sent to a microwave-ultrasonic reaction chamber with microwave power of 500W, ultrasonic power of 25Hz, and pulse of 5s / 5s for 20min. Finally, 10 times the volume of deionized water was added to terminate the reaction, and the mixture was centrifuged at 10000r / min to obtain a milky white suspension, which was denoted as nanocellulose suspension.

[0032] Example 14: Unlike Example 1, in the preparation method of nanofibers, the nanofibers were then placed in a dialysis bag and dialyzed with deionized water for 3 days until the pH was neutral. Then, 0.03 wt% chitosan was added to the dialysis suspension, and the nanofibers were obtained by centrifugation at 20°C and 9000 r / min.

[0033] Example 15: Unlike Example 1, in the preparation method of nanofibers, the nanofibers were then placed in a dialysis bag and dialyzed with deionized water for 5 days until the pH was neutral. Then, 0.05 wt% chitosan was added to the dialysis suspension, and the nanofibers were obtained by centrifugation at 30°C and 10000 r / min.

[0034] Example 16: Unlike Example 1, in S1, the nanofibers were dispersed in the aqueous phase at a weight ratio of 1:1 to the weight of the nanofibers and the aqueous phase components, and homogenized using a microfluidic homogenizer under conditions of 500 bar in the first stage and 50 bar in the second stage, for 10 cycles.

[0035] Example 17: Unlike Example 1, in S1, the nanofibers were dispersed in the aqueous phase at a weight ratio of 1:20 to the nanofibers, and homogenized using a microfluidic homogenizer at a first-stage pressure of 600 bar and a second-stage pressure of 60 bar, for 15 cycles.

[0036] Example 18: Unlike Example 1, in S2, phytosterols / phytosterol esters were dissolved in the oil phase component at a weight ratio of 1:5, and the mixture was heated to 40°C and stirred to obtain an oil phase containing phytosterols.

[0037] Example 19: Unlike Example 1, in S2, phytosterols / phytosterol esters were dissolved in the oil phase component at a weight ratio of 1:10, and the mixture was heated to 65°C and stirred to obtain an oil phase containing phytosterols.

[0038] Example 20: Unlike Example 1, in S3, the oil phase containing sterols was dispersed for 2 minutes at a speed of 400 rpm, and the oil phase was added to the nanofiber dispersion at a dropping rate of 90 g / min to obtain a crude emulsion; then the crude emulsion was subjected to high-pressure homogenization at a pressure of 30 MPa and homogenization times of 2.

[0039] Example 21: Unlike Example 1, in S3, the oil phase containing sterols was dispersed at 800 rpm for 5 min, and the oil phase was added to the nanofiber dispersion at a dropping rate of 100 g / min to obtain a crude emulsion; then the crude emulsion was subjected to high-pressure homogenization at a pressure of 60 MPa and a homogenization cycle of 4 times.

[0040] Example 22: Unlike Example 1, in S3, the powdering process is as follows: spray drying is carried out under the following conditions: the temperature inside the spray drying tower is controlled at 80°C, the air inlet temperature is 100°C, and the vacuum degree inside the tower is -0.8 MPa to obtain powder.

[0041] Example 23: Unlike Example 1, in S3, the powdering process is as follows: spray drying is carried out under the following conditions: the temperature inside the spray drying tower is controlled at 120°C, the air inlet temperature is 160°C, and the vacuum degree inside the tower is 1.0 MPa to obtain powder.

[0042] Example 24: Unlike Example 1, in S3, the powdering process is as follows: The above-mentioned O / W type Pickering emulsion is placed in a freeze dryer, the vacuum degree is controlled to be below 10 Pa, the material is pre-cooled to -70°C, and then the heating rate is controlled to be 8°C / h, the temperature is gradually increased to 20°C and held for 5h to obtain the dried product, which is then pulverized to obtain the powder product.

[0043] Example 25: Unlike Example 24, in S3, the powdering process is as follows: The above-mentioned O / W type Pickering emulsion is placed in a freeze dryer, the vacuum degree is controlled at 10 Pa, the material is pre-cooled to -80°C, and then the heating rate is controlled at 5°C / h, the temperature is gradually increased to 20°C and held for 4 hours to obtain the dried product, which is then pulverized to obtain the powder product.

[0044] Example 26: Unlike Example 24, in S3, the powdering process is as follows: The above-mentioned O / W type Pickering emulsion is placed in a freeze dryer, the vacuum degree is controlled at 10 Pa, the material is pre-cooled to -60°C, and then the heating rate is controlled at 10°C / h, the temperature is gradually increased to 20°C and held for 6 hours to obtain the dried product, which is then pulverized to obtain the powder product.

[0045] Example 27: Unlike Example 1, the application method is as follows: as a foliar spray or root treatment / irrigation agent: dilute the phytosterol Pickering emulsion to 500 times and apply it, then spray it on the crop leaves at 450 L / ha and irrigate the roots at 3 L / plant.

[0046] Example 28: Unlike Example 1, the application method is as follows: as a soil amendment / slow-release material: applied in the form of dry powder or emulsion, 10g of dry powder or 30g of emulsion per square meter of topsoil.

[0047] Experimental Example 1: Investigating the effect of the phytosterol pickering emulsion prepared in this application on drought resistance in maize. Experimental materials: The test reagent was a 5% phytosterol Pickering emulsion, prepared according to the method in Example 1, provided by Shaanxi Haisifu Biotechnology Co., Ltd.; the maize variety was Yudan 2275, purchased from Shaanxi Dadi Seed Industry (Group) Co., Ltd. Experimental design: Pot experiment, pot diameter 35 cm, height 25 cm; the culture soil was a mixture of commercial substrate (purchased from Yangling Sanli Chemical Glass Station) and farmland soil (2:1), 2.5 kg per pot. Seeds were soaked in 50, 100 and 200 times diluted 5% phytosterol emulsion. A blank control (CK0, drought stress) was set up without soaking, and water soaking (CK1) and normal water supply control (CK2) were also set up, for a total of 7 treatments. Select uniformly sized, disease-free maize seeds and soak them in a 1:3 ratio of seed weight to soaking solution for 12 hours. After soaking, remove the seeds, dry them, and sow them (September 15th). Sow 15 seeds per pot, with 3 pots per treatment. The soil moisture content at sowing was 14.5% (moderate drought), while the normal moisture control (CK2) had saturated soil moisture. After sowing, except for CK2 which received normal watering, the other treatments were subjected to drought stress. After CK2 seedlings emerged (1 week after sowing), quantitative water was added to the soil of the other treatments.

[0048] Measurement indicators and methods Emergence survey: After CK2 seedlings emerge, the emergence status is recorded daily; after all seedlings have emerged, the number of seedlings is investigated and the emergence rate is calculated.

[0049] Morphological indicators: Plant height, stem diameter, taproot length, and fresh weight (g / plant) of above-ground and underground parts were measured 24 days after sowing.

[0050] Experimental results: Table 1. Effects of 5% phytosterol seed soaking on maize emergence and seedling growth under drought stress.

[0051] Under soil drought stress (moisture content ≤14.5%), the emergence rate of maize one week after sowing was only 2.22% (CK0), while the emergence rate under normal water supply (CK2) was 82.22%, indicating that drought stress significantly inhibited maize emergence. Soaking seeds in 5% phytosterol at a dilution of 500-2000 times can improve maize emergence under drought stress, with a dilution of 1000 times increasing the emergence rate to a maximum of 31.11%. Figure 2 It can be seen that in the phytosterol Pickering emulsion, the nanofiber network structure hinders the aggregation of sterol-containing oil droplets; Figure 4 It can be seen that the application of phytosterol pickering emulsion can significantly improve the emergence of corn under drought stress; Experiment Example 2: Investigating the effects of phytosterol spray treatment on maize growth and yield Experimental materials: 5% phytosterol pickering emulsion, provided by Shaanxi Haisifu Biotechnology Co., Ltd.; 0.01% 24-epibrassinolide soluble concentrate, Dezhou Xiangnong Biochemical Co., Ltd. (commercially available).

[0052] Basic conditions for field experiment: The experiment was conducted in a cornfield in Wuxing Village, Yangling Demonstration Zone from July to September 2024. The corn was sown on June 10. The soil in the experimental site was loess with a pH of 6.9 and medium to high fertility. The previous crop was wheat. The corn was planted after being machine-tilled and was not watered during the growing period.

[0053] Experimental design: The experiment included 7 concentrations of 5% phytosterol emulsion (Table 2), 2000-fold dilution of 0.01% 24-epibrassinolide soluble concentrate (control), and a blank control, for a total of 9 treatments. Each treatment was replicated 3 times, resulting in a total of 27 plots arranged in a randomized block design. Each plot had an area of ​​40 (5m × 8m) m². 2 1080m in total 2On July 27, 2024 (50 days after sowing, tasseling stage, light rain on the 3rd day after spraying) and August 6, 2024 (60 days after sowing, most plants had tasseled and silked, light rain 4 hours after spraying, moderate rain 20 hours after spraying), a Weishi brand WS-16P backpack manual sprayer (manufactured by Shandong Weishi Plant Protection Co., Ltd.) was used for uniform spraying. The nozzle diameter was 1.3~1.5mm. The first application rate was 45kg / 667m². 2 The second time was 50kg / 667m 2 .

[0054] Table 2. Concentration of Test Reagents Used

[0055] Indicator testing methods: 15 days after the second application of pesticide (August 21), 10 corn plants with uniform growth in the middle row were randomly selected from each plot. The stem diameter (below the ear) and ear height were measured using calipers and a measuring tape, and the leaf color and any plant deformities were observed. Before corn harvest (September 22), the indicators were measured again at least once. At the same time, 20 ears were collected from each plot, and the fresh weight, ear length, ear diameter, number of rows per ear, number of kernels per row, and length of the barren tip were measured. After drying, the thousand-kernel weight was measured.

[0056] Experimental results: Table 3. Effects of different dilution ratios of phytosterol pickerine emulsion on maize stalk diameter and ear height.

[0057] Table 4. Effects of 5% phytosterol treatment on maize yield components.

[0058] The experimental results show that spraying 5% phytosterol at a dilution of 1000 times during the corn tasseling-silking stage can increase the stem diameter, ear length, ear diameter, number of kernels per ear, and thousand-kernel weight of corn plants, thereby making the corn plants grow more robustly and increasing the corn yield. It can be seen that the phytosterol Pickering emulsion obtained by the method in Example 1 of this application has the best stress resistance performance.

[0059] Using the emergence rate of maize one week after sowing under soil drought stress (moisture content ≤14.5%) as a basis, this study investigated the effects of the preparation method of phytosterol Pickering emulsion of nanofiber filaments on maize emergence rate and yield. The results are as follows: Comparative Example 1: Unlike Example 1, in the preparation method of nanofibers, the microwave-ultrasonic reaction treatment was replaced with single ultrasonic treatment in the post-processing.

[0060] Comparative Example 2: Unlike Example 1, chitosan oligosaccharide was not added in the preparation method of the nanofibers.

[0061] Comparative Example 3: Unlike Example 1, the aqueous phase component does not contain any additives.

[0062] Comparative Example 4: Unlike Example 1, the powdering process does not involve a gradient temperature increase.

[0063] Table 5. Performance comparison of phytosterol pickerine emulsions obtained from Examples 1-28 and Comparative Examples 1-4

[0064] Conclusions: A comparison of Examples 1, 12-13, and Control Example 1 shows that replacing the microwave-ultrasound reaction treatment with single-ultrasound treatment in Control Example 1 significantly reduced the water retention and dispersibility of the resulting nanofibers. When applied to arid soils, its effect in alleviating drought stress was significantly worse. Under drought stress, germination rate is highly dependent on the moisture environment surrounding the seeds. The nanofibers treated with single-ultrasound treatment have poor water retention capacity and cannot effectively maintain the humidity required for germination, leading to more seeds failing to absorb moisture and germinating, or drying out after germination. Seedling fresh weight reflects biomass accumulation. Increased water stress directly inhibits cell division and expansion, resulting in slow seedling growth, weak plants, and a significant decrease in fresh weight. Stem diameter is an important indicator of plant robustness and stress resistance. Under water stress, photosynthesis is hindered, assimilate supply decreases, and limited resources are preferentially allocated to the roots rather than the aboveground parts, resulting in inhibited stem thickening.

[0065] A comparison of Examples 1, 14-15, and Comparative Example 2 shows that in the preparation method of nanofibers in Comparative Example 2, without the addition of chitosan oligosaccharide, the nanofibers will undergo severe aggregation, leading to a significant decline in their core water-retention function and complete loss of biostimulation function. Ultimately, this results in a comprehensive and significant deterioration of all growth indicators of corn under drought stress. However, by adding chitosan oligosaccharide, it can form a thick coating with negatively charged CNF, significantly improving leaf adhesion rate. At the same time, chitosan oligosaccharide itself can induce systemic resistance in crops and synergistically enhance the effect with phytosterols, thereby improving the survival rate of crop seedlings under salt stress.

[0066] The comparison of Examples 1, 16-17 and Control Example 3 shows that the absence of potassium sorbate in the aqueous phase component of Control Example 3 will cause the emulsion system to collapse, preventing all functional components (nanofibers and phytosterols) from playing their due role in drought resistance and seedling protection. The final treatment effect is no different from that of the drought control group without any drought resistance treatment, and all growth indicators of corn show a state of severe drought stress.

[0067] The comparison of Examples 1, 22-26 and Control Example 4 shows that the lack of gradient heating in the powdering treatment in Control Example 4 leads to poor rehydration of the powder, which reduces its water retention and drought resistance. Ultimately, the emergence rate and growth of corn under drought stress are significantly worse than those of the fully optimized Example 1, but much better than the completely ineffective Control Example 3 (without preservatives) or the blank drought control group.

Claims

1. A phytosterol pickerine emulsion based on nanofibers, characterized in that, Based on parts by weight, it includes the following components: 0.5 to 1 part of nanofiber filaments; 1-10 parts of phytosterols / phytosterol esters; Aqueous phase component 95~105 parts; Oil phase component 95~105 parts; The nanofibers are extracted from agricultural waste, which includes any one or more of corn stalks, citrus peels, and sugarcane bagasse; the phytosterols are one of β-sitosterol, stigmasterol, brassosterol, and campesterol, or a mixture of any two to four of them in any proportion; the phytosterol esters are esters prepared by mixing phytosterols and fatty acids in a weight ratio of 1:1.1 to 1.4, where the fatty acids are any one of oleic acid, linoleic acid, and palmitic acid, or a mixture of two to three of them in any proportion.

2. The phytosterol pickerine emulsion based on nanofibers as described in claim 1, characterized in that, The method for preparing the nanofibers is as follows: (1) Agricultural waste pretreatment First, dry the agricultural waste with hot air at 55~65 ℃ until constant weight, then crush the dried agricultural waste to 40~80 mesh. (2) Steam explosion Then, the crushed agricultural waste is loaded into a sealed reaction vessel, and an ethanol-water solution is added at a ratio of 1~3g:10mL. The mixture is maintained at 170~180℃ and 1.0~1.2MPa for 5~7min, and then depressurized and flashed. (3) Alkali treatment The modified slurry is obtained by soaking in a 5-10 wt% alkaline solution at 70-90℃ for 4-8 hours, and then bleaching with a 0.8-1.2 wt% oxidant at 25-30℃ for 25-30 minutes. The alkaline solution is sodium hydroxide or potassium hydroxide; the oxidizing agent is NaClO2 or H2O2. (4) Post-processing The modified slurry was passed through a microfluidic homogenizer at 550-650 bar 2-4 times, and then treated in a microwave-ultrasonic reaction chamber with a microwave power of 300-500W, an ultrasonic power of 20-25Hz, and a pulse of 5s / 5s for 10-20 minutes. Finally, 8-10 times the volume of deionized water was added to terminate the reaction. The mixture was centrifuged at 8000-10000 r / min to obtain a milky white suspension, which was designated as the nanocellulose suspension. The suspension was then placed in a dialysis bag and dialyzed with deionized water for 3-5 days until the pH was neutral. After that, 0.03-0.05 wt% chitosan oligosaccharide was added to the dialyzed suspension, and the mixture was centrifuged and concentrated at 20-30℃ and 9000-10000 r / min to obtain nanofibers.

3. The phytosterol pickerine emulsion based on nanofibers as described in claim 1, characterized in that, The aqueous phase component is either deionized water or an aqueous solution containing a pH adjuster or a preservative; wherein the pH adjuster is an 18-20 wt% sodium hydroxide aqueous solution, which can adjust the pH of the system to 7.0-10.0; and the preservative is potassium sorbate or microbial E, with an addition amount of 0.01-0.1 wt%.

4. The phytosterol pickerine emulsion based on nanofibers as described in claim 1, characterized in that, The oil phase component is any one of soybean oil, sunflower oil, or rapeseed oil.

5. The method for preparing the phytosterol pickering emulsion based on nanofibers as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1, Preparation of Nanofiber Dispersion The nanofibers were dispersed in an aqueous phase at a weight ratio of 1:1 to 20 to water. The nanofibers were then homogenized using a microfluidic homogenizer at a first-stage pressure of 500 to 600 bar and a second-stage pressure of 50 to 60 bar, and the mixture was cyclicated 10 to 15 times to obtain a nanofiber dispersion. S2, Preparation of sterol-containing oil phase Plant sterols / plant sterol esters are dissolved in the oil phase component at a weight ratio of 1:5~10, and the mixture is heated to 40~65℃ and stirred to obtain an oil phase containing sterols. S3, Emulsion Preparation The oil phase containing sterols is dispersed at 400-800 rpm for 2-5 min, and then added to the nanofiber dispersion at a dropping rate not exceeding 90-100 g / min to obtain a crude emulsion. The crude emulsion is then subjected to high-pressure homogenization at a pressure of 30-60 MPa for 2-4 times to obtain a PNFs-stable, O / W type phytosterol Pickering emulsion based on nanofibers loaded with phytosterols / sterol esters.

6. The method for preparing the phytosterol pickering emulsion based on nanofibers as described in claim 5, characterized in that, The phytosterol pickerine emulsion based on nanofibers obtained in S3 was powdered. The powdering process is as follows: spray drying is carried out under the following conditions: the temperature inside the spray drying tower is controlled at 80~120℃, the inlet air temperature is 100~160℃, and the vacuum degree inside the tower is -0.8~1.0Mpa to obtain powder.

7. The method for preparing the phytosterol pickering emulsion based on nanofibers as described in claim 5, characterized in that, The phytosterol pickerine emulsion based on nanofibers obtained in S3 was powdered. The powdering process is as follows: the above-mentioned O / W type Pickering emulsion is placed in a freeze dryer, the vacuum degree is controlled to be below 10 Pa, the material is pre-cooled to -80℃ to -60℃, and then the heating rate is controlled to be 5 to 10℃ / h, the temperature is gradually increased to 20℃ and maintained for 4 to 6 hours to obtain the dried product, which is then pulverized to obtain the powder product.

8. The application of the phytosterol pickerine emulsion based on nanofibers as described in claim 7, characterized in that, It is used in the preparation of agricultural formulations that enhance crop stress resistance.

9. The application of the phytosterol pickerling emulsion based on nanofibers as described in claim 8, characterized in that, The application method is as follows: As a foliar spray or root treatment / irrigation agent: dilute the plant sterol pickering emulsion to 500-3000 times and apply it, then spray it on the crop leaves at 450-600 L / ha, or irrigate the roots at 3-5 L / plant. Alternatively, it can be used as a soil amendment / slow-release material: applied in the form of dry powder or emulsion, with 1-10g of dry powder or 20-30g of emulsion per square meter of topsoil.

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