Method for preparing small-particle-size red nano selenium particles and application of small-particle-size red nano selenium particles

Abstract

The invention relates to a method for preparing small-particle-size red nano-selenium particles and application of the small-particle-size red nano-selenium particles, and belongs to the technical field of selenium compounds. The nano-selenium particles contain nano-selenium and a lipoic acid oligomer. The preparation method comprises the following steps: respectively preparing nano-selenium and a lipoic acid oligomer, and uniformly mixing the nano-selenium and the lipoic acid oligomer to obtain the nano-selenium particles. The nano-selenium particles have good stability; the content of total protein and fat in highland barley grains to which the nano-selenium particles are applied is remarkably increased through detection, the nano-selenium particles become an effective means for selenium enrichment of crops, the nano-selenium particles are well applied to selenium-enriched planting of highland barley, and the application of the nano-selenium particles to the highland barley grains is developed by combining development of new selenium-enriched crop varieties and research of a new selenium fertilizer application technology. And a powerful promotion effect is achieved on the development of selenium-enriched ecological agriculture.

Description

Technical Field

[0001] This invention relates to a method for preparing small-diameter red selenium nanoparticles and its application, belonging to the field of selenium compound technology. Background Technology

[0002] Selenium is an essential trace element for the human body, possessing both metallic and nonmetallic chemical and physical characteristics. Selenium exhibits outstanding performance in enhancing immunity, antioxidation, antiviral activity, and anticancer properties. Selenium deficiency can lead to various diseases, such as thyroid disorders, diabetes, reproductive disorders, and obesity. However, my country is a selenium-deficient country, with 70% of its regions living in selenium-deficient or low-selenium environments. Because the human body's own selenium intake is limited, and the ingested selenium cannot be effectively absorbed and utilized to perform its important physiological functions, it is necessary to obtain it from the daily diet.

[0003] Selenium mainly enters the ground through volcanic / magmatic movements, and its average content in the Earth's crust is less than 0.1 mg / kg. The world soil selenium content ranges from 0.1 to 2.0 mg / kg. The selenium content in my country's soil varies greatly. The highest selenium content in the soil in Enshi, Hubei, known as the "Selenium Capital," can reach 45.5 mg / kg, while in the Keshan disease area it is only 0.06 to 0.18 mg / kg. According to the "China Soil Selenium Environmental Quality Standard" compiled by Zhang Dongwei et al. [3], more than 72% of my country's areas are low-selenium or selenium-deficient areas, and nearly 700 million people live in selenium-deficient environments. In terms of geographical distribution, my country's soil selenium is basically distributed in a saddle shape with low levels in the middle and high levels on both sides, and there is a low-selenium belt running from the northeast to the southwest.

[0004] Nano selenium is an elemental selenium with a diameter of approximately 20-500 nanometers. It is easily soluble in water and does not easily transform into a blackish-gray color. It has unique physicochemical properties such as small particle size, large specific surface area, low toxicity, and high solubility. Compared with traditional selenium supplements, nano selenium has higher bioavailability and bioactivity, and also has physiological functions such as anti-oxidation, antibacterial, and anti-tumor effects.

[0005] The synthesis of nano-selenium mainly involves three methods: chemical synthesis, physical synthesis, and biosynthesis. In the past few decades, chemical synthesis has been considered the most important route for synthesizing nano-selenium particles. Chemical synthesis mainly involves creating a reduction reaction system to reduce high-valence selenium to its elemental state, including catalytic reduction, precipitation, or decomposition methods.

[0006] The chemical reduction of nano-selenium typically involves adding stabilizers or dispersants and reducing agents to a sodium selenite solution. Stabilizers include polysaccharides, proteins, and surfactants. From the perspectives of environmental protection, energy conservation, and preparation methods, polysaccharides are more suitable as stabilizers for selenium nanoparticles than other materials such as proteins and polyphenols. Polysaccharides have active hydroxyl groups and complex branched structures, which can modify the interface of nanoparticles, control the growth of nanoparticles, and stabilize the nanoparticle solution.

[0007] Selenium nanoparticles were prepared by reducing selenite solution with ascorbic acid in the presence of some water-soluble polysaccharides, such as chitosan, konjac glucomannan, gum arabic, and carboxymethyl cellulose, resulting in monodisperse spherical selenium colloids. Furthermore, monodisperse selenium nanoparticles were synthesized using a simple method with chitosan as a stabilizer and carboxymethyl chitosan as a capping agent.

[0008] The effectiveness of selenium for plants and humans is gaining increasing attention, and more and more selenium-rich soils are being discovered and utilized. However, a systematic, comprehensive, and accurate understanding of the content, forms, transformations, and availability of selenium in soil is still lacking. Although nano-selenium exhibits good biological activity and low toxicity, its stability still needs optimization.

[0009] One technical approach to achieving material stability involves coating with film-forming materials. Commonly used film-forming materials include the following categories: 1. Polymer materials Polymer materials are among the most common types of film-forming materials. These materials include various plastics, rubbers, and resins. They possess excellent processability, physical and mechanical properties, and chemical stability. Polymer materials can be made into thin films, which are widely used in packaging, agriculture, electronics, and other fields.

[0010] 2. Inorganic materials Inorganic materials such as glass and ceramics can also be used as film-forming materials. These materials possess high hardness, chemical stability, and thermal stability. Thin films made from inorganic materials have wide applications in fields such as optics, electronics, and architecture.

[0011] 3. Metallic materials Metallic materials such as aluminum, copper, and steel also have wide applications in thin film form. Metallic thin films possess excellent electrical and thermal conductivity and mechanical strength. They are commonly used in electronics, communications, aerospace, and other fields.

[0012] 4. Composite film-forming materials Composite film-forming materials are composed of two or more materials. These materials combine the advantages of different materials, resulting in better overall performance. For example, composite materials of polymers and metals or ceramics can combine the good processability of polymers with the high hardness and high thermal stability of metals or ceramics.

[0013] Film-forming materials refer to materials that can form thin films and are widely used in various fields. The polymer materials, inorganic materials, metallic materials, and composite film-forming materials mentioned above are all common types of film-forming materials. The films formed by these materials have different properties and functions, meeting diverse application requirements. From packaging to electronics, from construction to aerospace, film-forming materials play a vital role.

[0014] Austrian patent publication AT503901A1 discloses a compound of lipoic acid and amino acids. Lipoic acid, as a coenzyme, plays a role in two key oxidative decarboxylation reactions: pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex, catalyzing the generation and transfer of acyl groups. Lipoic acid can accept an acyl group from the acetyl group of pyruvate to form a thioester bond, and then transfer the acetyl group to the sulfur atom of the coenzyme A molecule. The dihydrolipoamide forming the coenzyme group can be further oxidized by dihydrolipoamide dehydrogenase (requiring NAD+) to regenerate oxidized lipoamide. α-Lipoic acid contains a disulfide five-membered ring structure with a high electron density, exhibiting significant electrophilicity and the ability to react with free radicals; therefore, it possesses antioxidant properties and has extremely high health benefits and medicinal value (such as anti-fatty liver and cholesterol-lowering effects). Furthermore, the thiol group of lipoic acid readily undergoes redox reactions, thus protecting thiol enzymes from the toxicity of heavy metal ions. Alpha-lipoic acid is widely distributed in nature, especially abundant in liver and yeast cells. It often co-occurs with vitamin B1 in food. The human body can synthesize it. No alpha-lipoic acid deficiency has been found in humans. AT503901A1 provides a substance with high antioxidant activity of alpha-lipoic acid, achieved by a method comprising the following steps: a) The conversion of an amino acid and α-lipoic acid in an aqueous solution; b) Keep the solution at high temperature for 1-5 hours, preferably 3 hours; c) Compounds formed by precipitation from a concentrated solution through mixing with an alcoholic solution; d) Collect the precipitated compound from the mixed solution.

[0015] The product obtained through the above method, in addition to possessing the properties of α-lipoic acid, also exhibits excellent film-forming properties and can be applied in the food and cosmetic fields. Specifically, using the product obtained through the above method as a film-forming material to encapsulate carotenoids or carotenoid derivatives helps improve the stability of carotenoids or carotenoid derivatives, providing a protective mechanism for carotenoids or carotenoid derivatives as food nutrients, with excellent protective effects.

[0016] The trace element selenium has various biological functions and is of great significance for the growth and development of plants and animals, as well as human health. When the selenium intake from food is insufficient to meet the body's needs, applying selenium compounds to crops to produce selenium-enriched agricultural products is beneficial for human absorption and avoids excessive selenium supplementation, making selenium utilization safe and reliable. This review summarizes the research progress on the effects of exogenous selenium fertilizers on crop growth, development, quality, selenium enrichment capacity, and interactions with other nutrients. Combining the development of new selenium-enriched crop varieties with research on new selenium fertilizer application technologies will strongly promote the development of selenium-enriched ecological agriculture.

[0017] The absorption and utilization of selenium by plants is a major research topic in agriculture and a key area for selenium enrichment research on major crops. Appropriate or low levels of selenium have a stimulating effect on plant growth. When selenium is applied to the nutrient solution of Chinese cabbage, a selenium concentration ≤1.0 mg / L promotes growth; however, a concentration ≥2.5 mg / L inhibits growth. Experiments have shown that adding an appropriate amount of exogenous selenium to the culture medium significantly increases the biological growth of mutant Dianthus chinensis, demonstrating a significant growth-promoting effect. When the selenium concentration is between 0 and 1.0 mg / kg, the height and root activity of potted soybean plants increase with increasing selenium concentration; however, when the concentration increases to above 20.0 mg / kg, the plant height and root activity decrease, exhibiting a certain growth-inhibiting effect. Spraying grapevines with amino acid selenium significantly improves leaf quality, increases leaf thickness, and enhances branch maturity. Extensive experimental data confirm that appropriate concentrations of selenium have a significant promoting effect on plant growth and development. Summary of the Invention

[0018] The purpose of this invention is to provide a nano-selenium particle, wherein the nano-selenium particle is a small-diameter red nano-selenium particle.

[0019] Another object of the present invention is to provide a method for preparing the above-mentioned small-diameter red selenium nanoparticles.

[0020] Another object of the present invention is to provide applications of the above-mentioned small-diameter red selenium nanoparticles, especially in the selenium-enriched cultivation of highland barley.

[0021] The nano-selenium particles contain nano-selenium and thioctic acid oligomers, and the nano-selenium particles have good stability.

[0022] The preparation method of the nano-selenium is as follows: dissolve selenium powder and sodium sulfite in water, heat to 100°C, let stand, filter, mix the filtrate with polyvinylpyrrolidone solution evenly, add buffer solution dropwise, stir, let stand, separate and dry to obtain nano-selenium.

[0023] The mass ratio of the selenium powder to the sodium sulfite is 1:2 to 1:5; preferably 1:2.5, and the sodium sulfite is preferably anhydrous sodium sulfite.

[0024] The mixture of selenium powder and sodium sulfite is heated to 100°C and maintained for 8-12 hours.

[0025] The preferred heating method is reflux heating, and the preferred reflux time is 10 hours.

[0026] The preferred mass concentration of the polyvinylpyrrolidone solution is 1%.

[0027] The buffer solution is preferably a citric acid-sodium citrate buffer solution.

[0028] The citric acid-sodium citrate buffer solution can be a commercially available product, preferably prepared on-site.

[0029] The method for preparing the citric acid-sodium citrate buffer solution is as follows: weigh citric acid and dissolve it in distilled water, then add sodium hydroxide solution dropwise under stirring until the pH value is 4.5-5.0, and set aside for later use.

[0030] The lipoic acid oligomer is preferably a salt of oligomeric lipoic acid and an amino acid.

[0031] The preferred amino acid is lysine.

[0032] The method for preparing the oligomeric lipoic acid and amino acid salt is as follows: dissolve lipoic acid and amino acid in water, heat to 30℃-50℃, maintain for 1-5 hours, add ethanol, and the precipitate is the obtained product.

[0033] In the salt obtained by the above method, the molar ratio of lipoic acid to amino acids is 1:1 to 5:1.

[0034] The above-mentioned nano-selenium was uniformly mixed with oligomeric lipoic acid and an amino acid salt to obtain the nano-selenium particles of the present invention. The inventors unexpectedly discovered that the nano-selenium particles exhibit good stability due to the antioxidant properties of the oligomeric lipoic acid and amino acid salt.

[0035] The nano-selenium is uniformly mixed with oligomeric thioctic acid and amino acid salts, and spray drying is preferred.

[0036] Spray drying is usually the final step in the manufacturing process, transforming a substance from a liquid or fluid into a powder through continuous spraying, mixing, and drying. Among many food preservation technologies, spray drying has unique advantages. Because the temperatures used in this technology are not very high, it effectively preserves the flavor, color, and nutrients of food while removing microbial contamination. Spray drying is characterized by rapid heat transfer, rapid moisture evaporation, and short drying time, resulting in high-quality products with a crisp texture and good solubility. It can improve the dissolution rate of certain formulations and is suitable for heat-sensitive drugs. Furthermore, spray drying can be used to prepare microcapsules. Spray drying is commonly used to remove moisture from raw materials. In addition, it has many other applications, such as changing the size, shape, or density of substances. It can also assist in the addition of other ingredients during the production process, contributing to the production of products with the strictest quality standards.

[0037] Currently, three main types of spray drying equipment are used in China: pressure spray drying, centrifugal spray drying, and airflow spray drying. The difference lies in the route taken to transport the liquid material into the drying chamber. Pressure spray drying utilizes a high-pressure pump with pressure ranging from 7.09 × 10⁶ Pa to 2.03 × 10⁷ Pa; centrifugal spray drying uses a horizontally rotating high-speed disc to apply centrifugal force to the solution, causing it to be ejected at high speed; and airflow spray drying involves the wet material being conveyed and simultaneously mixed with heated air into the dryer, allowing for more thorough mixing.

[0038] The raw material liquid can be a solution, emulsion, or suspension, or it can be a melt or paste. The dried product can be made into powder, granules, hollow spheres, or agglomerates as needed.

[0039] The JOYN-8000B all-stainless steel spray dryer is mainly suitable for producing micro-particle powders. It has broad applicability to all solutions such as emulsions and suspensions. It is suitable for drying heat-sensitive materials such as biological products, biopharmaceuticals, and enzyme preparations. Because the material is only exposed to high temperature when it is sprayed into a mist-like particle size, it is only heated momentarily, which can keep the active ingredients of these active materials intact after drying.

[0040] This application discloses a method for preparing small-diameter red selenium nanoparticles, wherein the selenium nanoparticles contain selenium nanoparticles and lipoic acid oligomers. The preparation method of the selenium nanoparticles is as follows: dissolving selenium powder and sodium sulfite in water, heating to 100°C, allowing to stand, filtering, mixing the filtrate with polyvinylpyrrolidone solution, adding a buffer solution dropwise, stirring, allowing to stand, separating and drying to obtain selenium nanoparticles; the lipoic acid oligomer is a salt of oligomeric lipoic acid and amino acids; the preparation method of the salt is as follows: dissolving lipoic acid and amino acids in water, heating to 30°C-50°C, maintaining for 1-5 hours, adding ethanol, and the precipitate is the obtained product; mixing the above-mentioned selenium nanoparticles with the salt of oligomeric lipoic acid and amino acids evenly to obtain the product.

[0041] In a preferred embodiment, the mass ratio of the selenium powder to the sodium sulfite is 1:2 to 1:5.

[0042] In a preferred embodiment, the mass ratio of the selenium powder to the sodium sulfite is preferably 1:2.5.

[0043] In the preferred embodiment, the heating step in the above method is controlled at 100°C and maintained for 8-12 hours.

[0044] In a preferred embodiment, the polyvinylpyrrolidone solution has a mass concentration of 1%.

[0045] In a preferred embodiment, the buffer solution is a citric acid-sodium citrate buffer solution.

[0046] In a preferred embodiment, the amino acid is lysine.

[0047] In a preferred embodiment, the molar ratio of lipoic acid to amino acids in the salt is 1:1 to 5:1.

[0048] In a preferred embodiment, the nano-selenium and oligomeric thioctic acid and amino acid salts are uniformly dissolved in water and then spray-dried.

[0049] The nano-selenium particles obtained by the above method have excellent applications in the cultivation of selenium-enriched highland barley.

[0050] Highland barley is characterized by its low fat, low sugar, high protein, high fiber, and high vitamin content. Its protein, β-glucan, starch, lipids, trace elements, vitamins, and abundant polyphenols play a positive role in the treatment of obesity, high blood sugar, high blood pressure, high cholesterol, and cancer. Selenium is an essential trace element with important physiological functions and a wide range of pharmacological effects. Adequate selenium supplementation can enhance the body's immunity and delay aging. However, selenium cannot be directly absorbed by the human body; therefore, it indirectly affects the human body by influencing the quality of crops and improving certain nutritional components in agricultural products. Nano-selenium, existing at the nanoscale, possesses unique physicochemical properties, such as high biological activity, low toxicity, and better absorption, making it a safer and more reliable form of selenium supplementation with promising application prospects.

[0051] Appropriate amounts of selenium can enhance plant photosynthesis, primarily by promoting chlorophyll synthesis and metabolism, thus increasing chlorophyll accumulation in leaves. In lettuce pot experiment, foliar spraying with selenium at concentrations of 0–4.0 mg / L showed a positive correlation between chlorophyll content and selenium concentration. The effect of selenium on increasing chlorophyll content varies among different plants; the beneficial selenium concentration for carrot chlorophyll synthesis is below 10.0 mg / kg, while for pepper chlorophyll synthesis it is below 0.9 mg / kg. Selenium can also improve plant photosynthetic efficiency, as verified in experiments with soybeans and tomatoes. Applying selenium to early rice at the tillering stage increased stomatal CO2 flux, reduced stomatal resistance, and significantly increased net photosynthetic rate compared to the control. Studies have also found that selenium may participate in plant energy metabolism; appropriate amounts of selenium significantly promoted electron transport rate in rice chloroplasts, while also significantly increasing mitochondrial respiration rate and oxidative phosphorylation efficiency, and significantly enhancing mitochondrial activity.

[0052] Enzymatic scavenging systems such as SOD, POD, and CAT, along with non-enzymatic scavenging systems such as AsA and GSH, constitute important antioxidant defense systems in plant cells against free radicals. Selenium, known as a "scavenger" of reactive oxygen species, directly participates in the removal of excess reactive oxygen species within plants. Selenium plays a crucial antioxidant role in both enzymatic and non-enzymatic defense systems, thereby enhancing plant immunity and resistance to adverse conditions. Proline accumulation in most plants may be a signal of external stress, and experiments have confirmed that proline accumulation levels can serve as an important indicator for evaluating plant resistance to adverse stress. Applying selenium fertilizer to alfalfa significantly promotes the accumulation of free proline in its leaves.

[0053] Selenium can effectively antagonize heavy metals and alleviate abiotic stress damage in plants, enhancing their resistance to adverse conditions. Experiments have shown that low concentrations of selenium treatment can promote the growth and increase various physiological activities of rapeseed under cadmium stress, with selenium and cadmium exhibiting antagonistic effects. In experiments applying selenium to grape seedlings under drought conditions, the application slowed the rate of chlorophyll decomposition in grape leaves, increased proline and soluble sugar content, and also regulated the activities of CAT, SOD, POD, and GSH-Px enzymes, while reducing MDA content, significantly mitigating the inhibition of photosynthesis in grape seedlings.

[0054] Barley, a variety of the genus *Hordeum* in the Poaceae family, is a special type of barley with higher nutritional content than crops such as rice, wheat, and corn. Barley can be used not only for food, animal feed, and brewing, but also for medicinal purposes. In the Qinghai-Tibet Plateau region, barley is considered one of the main dominant crops. It contains various amino acids and proteins, and is also rich in inorganic salts, vitamins, phenols, sterols, and flavonoids, among other bioactive substances. These components give barley superior health benefits, especially the flavonoids, which possess various pharmacological activities, including antioxidant, antibacterial, lipid-lowering, and blood sugar-lowering functions, and have wide clinical applications. Therefore, barley is considered a very high-quality cereal crop with a positive effect on human health. Consequently, selenium-enriched barley cultivation has become a research focus. In barley grains treated with the aforementioned nano-selenium particles, the total protein and fat content significantly increased, demonstrating an effective method for selenium enrichment in crops. Attached Figure Description

[0055] Figure 1 To compare the selenium content in the roots of barley with that of the nano-selenium particles in Experiment 1, barley was planted with nano-selenium particles. The selenium content in the roots of barley increased rapidly, and the absorption effect of nano-selenium particles by the roots of barley was obvious.

[0056] Figure 2 This is a comparison of the selenium content in the roots of barley in Experiment Example 2 between the nano-selenium particles and the blank sample. Detailed Implementation

[0057] Example 1 Preparation of nano-selenium: Weigh 5 g of selenium powder (AR grade, Tianjin Chemical Reagent Research Institute) and 12 g of anhydrous sodium sulfite (AR grade, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.). Measure 150 mL of distilled water using a graduated cylinder and place it in a round-bottom flask for reflux. The reflux temperature is controlled at 100℃ and the reflux time is 10 h. After standing for a period of time, filter the solution and take the clear solution for later use.

[0058] Weigh 100g of citric acid and dissolve it in 200mL of distilled water. While stirring, add 10% sodium hydroxide solution dropwise until the pH value is equal to 4.5. Set the solution aside.

[0059] A 1% polyvinylpyrrolidone solution (AR grade, product of Tianjin Guangfu Fine Chemical Research Institute) was added to the solution and mixed thoroughly. Then, it was added dropwise to a citric acid-sodium citrate buffer solution while stirring. After standing for a period of time, the solution was centrifuged, washed several times with distilled water, and then dried in a freeze dryer to obtain nano-selenium.

[0060] Preparation of oligomeric thioctic acid salts: Dissolve 10g of lysine and 20g of α-lipoic acid in water, heat to 50°C, maintain for 4 hours, and then add ethanol until the precipitate is stable to obtain a poly(lipoic acid) salt of lysine.

[0061] Preparation of nano-selenium particles: The above-mentioned nano-selenium and salt were mixed evenly at a 1:1 mass ratio, dissolved in water, and then spray-dried to obtain nano-selenium particles. The spray-drying operation was carried out under the following conditions: Inlet air temperature: 190℃ Outlet temperature: 80℃ Air-product contact time: 2 seconds Air volume relative to product weight: 300m³ 3 / kg.

[0062] Example 2 Preparation of nano-selenium: Weigh 5 g of selenium powder (AR grade, Tianjin Chemical Reagent Research Institute) and 10 g of anhydrous sodium sulfite (AR grade, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.). Measure 200 mL of distilled water using a graduated cylinder and place it in a round-bottom flask for reflux. The reflux temperature is controlled at 100℃ and the reflux time is 10 h. After standing for a period of time, filter the solution and take the clear solution for later use.

[0063] Weigh 100g of citric acid and dissolve it in 200mL of distilled water. While stirring, add 10% sodium hydroxide solution dropwise until the pH value is equal to 4.8. Set the solution aside.

[0064] A 1% polyvinylpyrrolidone solution (AR grade, product of Tianjin Guangfu Fine Chemical Research Institute) was added to the solution and mixed thoroughly. Then, it was added dropwise to a citric acid-sodium citrate buffer solution while stirring. After standing for a period of time, the solution was centrifuged, washed several times with distilled water, and then dried in a freeze dryer to obtain nano-selenium.

[0065] Preparation of oligomeric thioctic acid salts: Dissolve 10g of lysine and 30g of α-lipoic acid in water, heat to 30°C, maintain for 1 hour, and then add ethanol until the precipitate is stable to obtain a poly(lipoic acid) salt of lysine.

[0066] Preparation of nano-selenium particles: The above-mentioned nano-selenium and salt were mixed evenly at a mass ratio of 1:2, dissolved in water, and then spray-dried to obtain nano-selenium particles. The spray-drying operation was carried out under the following conditions: Inlet air temperature: 170℃ Outlet temperature: 85℃ Air-product contact time: 2 seconds Air volume relative to product weight: 300m³ 3 / kg.

[0067] Example 3 Preparation of nano-selenium: Weigh 5 g of selenium powder (AR grade, Tianjin Chemical Reagent Research Institute) and 15 g of anhydrous sodium sulfite (AR grade, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.). Measure 220 mL of distilled water using a graduated cylinder and place it in a round-bottom flask for reflux. The reflux temperature is controlled at 100℃ and the reflux time is 10 h. After standing for a period of time, filter the solution and take the clear solution for later use.

[0068] Weigh 100g of citric acid and dissolve it in 200mL of distilled water. While stirring, add 10% sodium hydroxide solution dropwise until the pH value is equal to 4.9. Set the solution aside.

[0069] A 1% polyvinylpyrrolidone solution (AR grade, product of Tianjin Guangfu Fine Chemical Research Institute) was added to the solution and mixed thoroughly. Then, it was added dropwise to a citric acid-sodium citrate buffer solution while stirring. After standing for a period of time, the solution was centrifuged, washed several times with distilled water, and then dried in a freeze dryer to obtain nano-selenium.

[0070] Preparation of oligomeric thioctic acid salts: Dissolve 10g of lysine and 35g of α-lipoic acid in water, heat to 40°C, maintain for 5 hours, and then add ethanol until the precipitate is stable to obtain a poly(lipoic acid) salt of lysine.

[0071] Preparation of nano-selenium particles: The above-mentioned nano-selenium and salt were mixed evenly at a mass ratio of 2:1. Dissolved in water, the product is spray-dried to obtain nano-selenium particles. The spray-drying process is carried out under the following conditions: Inlet air temperature: 190℃ Outlet temperature: 85℃ Air-product contact time: 1 second Air volume relative to product weight: 400m³ 3 / kg.

[0072] Example 4 Preparation of nano-selenium: Weigh 5 g of selenium powder (AR grade, Tianjin Chemical Reagent Research Institute) and 20 g of anhydrous sodium sulfite (AR grade, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.). Measure 300 mL of distilled water using a graduated cylinder and place it in a round-bottom flask for reflux. The reflux temperature is controlled at 100℃ and the reflux time is 10 h. After standing for a period of time, filter the solution and take the clear solution for later use.

[0073] Weigh 100g of citric acid and dissolve it in 200mL of distilled water. While stirring, add 10% sodium hydroxide solution dropwise until the pH value is equal to 4.6. Set the solution aside.

[0074] A 1% polyvinylpyrrolidone solution (AR grade, product of Tianjin Guangfu Fine Chemical Research Institute) was added to the solution and mixed thoroughly. Then, it was added dropwise to a citric acid-sodium citrate buffer solution while stirring. After standing for a period of time, the solution was centrifuged, washed several times with distilled water, and then dried in a freeze dryer to obtain nano-selenium.

[0075] Preparation of oligomeric thioctic acid salts: Dissolve 10g of lysine and 25g of α-lipoic acid in water, heat to 35°C, maintain for 3 hours, and then add ethanol until the precipitate is stable to obtain a poly(lipoic acid) salt of lysine.

[0076] Preparation of nano-selenium particles: The above-mentioned nano-selenium and salt were mixed evenly at a 1:1 mass ratio, dissolved in water, and then spray-dried to obtain nano-selenium particles. The spray-drying operation was carried out under the following conditions: Inlet air temperature: 180℃ Outlet temperature: 80℃ Air-product contact time: 2 seconds Air volume relative to product weight: 300m³ 3 / kg.

[0077] Example 5 Preparation of nano-selenium: Weigh 5 g of selenium powder (AR grade, Tianjin Chemical Reagent Research Institute) and 25 g of anhydrous sodium sulfite (AR grade, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.). Measure 300 mL of distilled water using a graduated cylinder and place it in a round-bottom flask for reflux. The reflux temperature is controlled at 100℃ and the reflux time is 10 h. After standing for a period of time, filter the solution and take the clear solution for later use.

[0078] Weigh 100g of citric acid and dissolve it in 200mL of distilled water. While stirring, add 10% sodium hydroxide solution dropwise until the pH value is equal to 4.7. Set the solution aside.

[0079] A 1% polyvinylpyrrolidone solution (AR grade, product of Tianjin Guangfu Fine Chemical Research Institute) was added to the solution and mixed thoroughly. Then, it was added dropwise to a citric acid-sodium citrate buffer solution while stirring. After standing for a period of time, the solution was centrifuged, washed several times with distilled water, and then dried in a freeze dryer to obtain nano-selenium.

[0080] Preparation of oligomeric thioctic acid salts: Dissolve 10g of lysine and 15g of α-lipoic acid in water, heat to 45°C, maintain for 2 hours, and then add ethanol until the precipitate is stable to obtain a poly(lipoic acid) salt of lysine.

[0081] Preparation of nano-selenium particles: The above-mentioned nano-selenium and salt were mixed evenly at a mass ratio of 1:1. Dissolved in water, the product is spray-dried to obtain nano-selenium particles. The spray-drying process is carried out under the following conditions: Inlet air temperature: 190℃ Outlet temperature: 80℃ Air-product contact time: 2 seconds Air volume relative to product weight: 300m³ 3 / kg.

[0082] Experimental Example 1 Experimental materials: Barley seeds (CDU-65), Chengdu University Key Laboratory of Coarse Grain Processing.

[0083] Experimental methods: The experiment was conducted in farmland in Sichuan Province from September 2024 to March 2025. The soil in the experimental area was mainly purple soil and alluvial soil, suitable for cultivation. During the experiment, the average temperature was about 15℃, the average precipitation was about 831 mm, the average sunshine duration was 1200 hours, and the climate was mild.

[0084] Land preparation: Select a planting plot with good irrigation conditions and ideal fertility. Before planting, carry out deep plowing and harrowing, and apply base fertilizer according to conventional planting methods. The amount of base fertilizer per square meter is: 2.5 kg of organic fertilizer, 5 g of urea, and 40 g of potassium sulfate. All of these should be applied into the soil during land preparation.

[0085] Sowing: Select high-quality highland barley seeds, remove mold and impurities and sun-dry the seeds, and treat them with 50% carbendazim wettable powder at the conventional dosage; sowing is done by machine row sowing, controlling the row spacing to 20cm, the sowing depth to about 5cm, and the sowing amount to be controlled to about 12kg per mu. Topdressing: When the barley has two leaves and one heart, weed and water it, and apply 5 kg / mu of urea. When the barley is at the jointing stage, apply 5 kg / mu of urea and 3 kg / mu of potassium sulfate. Foliar fertilization should also be carried out at appropriate times, with appropriate amounts of 2 wt% boron fertilizer and 1 wt% potassium dihydrogen phosphate sprayed. After the barley seedlings emerge, spray them with the nano-selenium particle solution from Examples 1-5. Pure water spraying serves as a blank control group. Each treatment has 3 replicates. The concentration of nano-selenium particles is 0.25 g / L. Then, during the middle growth stage of the barley seedlings, spray the barley again with the same concentration of nano-selenium particles. Lodging control: Apply a lodging regulator to the leaves of barley plants in the early stage of jointing. The lodging regulator includes the following components at the following mass concentrations: 40g / kg of Rainbow Jade Juice (physically squeezed juice), 0.02mg / kg of brassinolide, and 80g / kg of potassium dihydrogen phosphate. Control the amount to be applied at approximately 20kg / mu. Irrigation: During the seedling and flowering stages of barley and in irrigation canals, appropriate irrigation should be carried out. The amount of water should not be excessive at one time, but should be applied in small amounts and multiple times. In the early stage of jointing, water and fertilizer should be controlled appropriately to keep the soil surface in a relatively dry state, which is conducive to the compaction of the basal internodes and enhances the lodging resistance. Harvest at the appropriate time.

[0086] Sampling of barley seedlings in the middle stage of growth: 3-5 barley seedlings were collected for each treatment. The barley seedlings were pulled up by the roots and the roots were stored in a -20℃ refrigerator for testing.

[0087] The roots of barley seedlings were dried. When measuring, 0.25–0.5 g of the sample to be tested (accurate to 0.0001 g) was weighed. The microwave digestion temperature program is shown in Table 1, referring to "HJ 832-20175 Microwave Digestion Method for Total Metal Elements in Soil Sediments". Table 1: Microwave Digestion Heating Program

[0088] The experimental results are shown in Table 2. Table 2: Selenium content in barley roots

[0089] It can be seen that nano-selenium particles significantly increased the selenium content in the roots of highland barley. Without the addition of nano-selenium particles, the selenium content in the roots was 0.08 mg / mL; with the addition of nano-selenium particles, the selenium content in the roots increased rapidly, indicating a significant absorption effect of nano-selenium particles by the roots. Figure 1 .

[0090] Experiment Example 2 Experimental location: Maxiu Temple Experimental Base, Xihai Town, Haiyan County, Haibei Prefecture, Qinghai Province Before the experiment, the soil at the experimental site was analyzed, and the selenium content of the soil was measured to be 0.1 mg / Kg.

[0091] The experiment included five treated samples and one blank. The five treated samples used the nanoparticles prepared in Examples 1-5, respectively.

[0092] Fertilization treatment: Apply 15 kg / mu of diammonium phosphate and 5 kg / mu of urea; Organic fertilizer replaces 50% of chemical fertilizer (OPTM). Apply 300 kg / mu of commercial organic fertilizer (produced by Haibei Plateau Meiguobao Organic Fertilizer Co., Ltd.), 7.5 kg / mu of diammonium phosphate, and 2.5 kg / mu of urea. 50% replacement of chemical fertilizer with carbon-based organic fertilizer (OPTC): 300 kg / mu of carbon-based organic fertilizer, 7.5 kg / mu of diammonium phosphate, and 2.5 kg / mu of urea as base fertilizer.

[0093] Special fertilizer (OPTZ): Special fertilizer (17 15 8 B0.6Zn2.2) 29.4 kg / mu.

[0094] Except for the fertilization method, all five treatments followed the same field management practices.

[0095] After the barley seedlings emerged, they were sprayed with the nano-selenium particle solution from Examples 1-5. Pure water spraying served as a control group. Each treatment was performed in triplicate. The concentrations of the nano-selenium particles were 0.25 g / L, 0.30 g / L, 0.35 g / L, 0.40 g / L, and 0.50 g / L, respectively. Then, during the mid-growth stage of the barley seedlings, the barley was sprayed again with the same concentration of nano-selenium particles.

[0096] Irrigation: During the seedling and flowering stages of barley, and in irrigation canals, appropriate irrigation should be carried out. The amount of water should not be excessive at one time, but should be applied in small amounts and multiple times. In the early stage of jointing, water and fertilizer should be controlled appropriately to keep the soil surface in a relatively dry state, which is conducive to the compaction of the basal internodes and enhances the lodging resistance.

[0097] Table 2: Selenium content in barley roots

[0098] The comparison of selenium content in barley roots is shown in the figure. Figure 2 . The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing small-diameter red selenium nanoparticles, characterized in that, The nano-selenium particles contain nano-selenium and lipoic acid oligomers; The preparation method of the nano-selenium is as follows: dissolve selenium powder and sodium sulfite in water, heat to 100°C, let stand, filter, mix the filtrate with polyvinylpyrrolidone solution evenly, add buffer solution dropwise, stir, let stand, separate and dry to obtain nano-selenium; The lipoic acid oligomer is a salt of oligomeric lipoic acid and amino acids; The method for preparing the salt is as follows: dissolve lipoic acid and amino acids in water, heat to 30℃-50℃, maintain for 1-5 hours, add ethanol, and the precipitate is the obtained product; The above-mentioned nano-selenium was mixed evenly with oligomeric thioctic acid and amino acid salts to obtain the product.

2. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The mass ratio of the selenium powder to the sodium sulfite is 1:2 to 1:

5.

3. The method for preparing small-diameter red selenium nanoparticles according to claim 2, characterized in that, The mass ratio of the selenium powder to the sodium sulfite is 1:2.

5.

4. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The temperature is raised to 100°C and maintained for 8-12 hours.

5. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The polyvinylpyrrolidone solution has a mass concentration of 1%.

6. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The buffer solution is a citric acid-sodium citrate buffer solution.

7. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The amino acid in question is lysine.

8. The method for preparing small-particle-size red selenium nanoparticles according to claim 7, characterized in that, The molar ratio of lipoic acid to amino acids in the salt is 1:1 to 5:

1.

9. The method for preparing small-diameter red selenium nanoparticles according to claim 1, characterized in that, The nano-selenium, oligomeric thioctic acid, and amino acid salts are uniformly dissolved in water and then spray-dried.

10. The application of the nano-selenium particles obtained by the method according to any one of claims 1-9 in the selenium-enriched cultivation of highland barley.

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