Selenium nanoparticles and preparation method thereof

Abstract

The invention relates to the technical field of selenium nano materials, in particular to selenium nano particles and a preparation method thereof. According to the method, selenourea is used as a selenium source, selenium simple substance is prepared through oxidation reaction, deoxysodium cholate is used as a stabilizer to prepare micelles, and selenium nanoparticles with uniform size and diameter and good dispersity can be simply prepared. Compared with a traditional method, the method has the advantages that a reducing agent is not needed, the high toxicity risk caused by selenium salt such as sodium selenite is avoided, meanwhile, oxygen serves as a green oxidizing agent, natural biomolecular bile salt with biocompatibility serves as a stabilizer, only one-step reaction is needed, complex reaction conditions are not needed, and therefore the method is more suitable for preparing the selenium nano material in batches; the method is safe in raw materials, green in process, excellent in product performance, easy to industrialize and wide in application prospect.

Description

Technical Field

[0001] This invention relates to the field of selenium nanomaterials technology, specifically to a selenium nanoparticle and its preparation method. Background Technology

[0002] Selenium is an essential trace element for both plants and animals. In plants, selenium participates in regulating growth and development, enhancing antioxidant capacity, and improving resistance to biotic stresses (such as pathogen infection) and abiotic stresses (such as drought and heavy metals), playing a crucial role in maintaining crop health and improving yield and quality. For animals and humans, selenium plays an irreplaceable role in enhancing immunity, scavenging free radicals, and maintaining metabolic balance; selenium deficiency can lead to a series of physiological diseases. Currently, preparations for selenium supplementation in plants and animals can be mainly divided into inorganic selenium (such as sodium selenite) and organic selenium (such as selenomethionine and yeast selenium); however, both types of selenium sources have significant limitations. Inorganic selenium (mainly selenite) is highly toxic, has a narrow safety window, easily causes selenium poisoning in plants and animals, and is easily fixed in soil, resulting in low plant absorption and utilization rates. While the bioavailability of organic selenium has improved, its preparation process is complex and costly, its systemic absorption efficiency is poor, and it still carries certain risks of chronic toxicity, limiting its large-scale application.

[0003] Nano-selenium consists of elemental selenium particles at the nanoscale. Due to its surface and small size effects, it exhibits high bioactivity, with toxicity far lower than sodium selenite and organoselenium. The window between effective and toxic doses is significantly widened, making it a highly promising and safe selenium nutritional supplement. Currently, various methods exist for preparing nano-selenium, with liquid-phase chemical methods being the most common, such as template methods (proteins, polysaccharides), surfactant-mediated methods, and solid-phase reactions. However, its preparation technology still faces the following challenges: chemical reduction methods use highly toxic selenium salts and strong reducing agents, posing safety and environmental risks; biosynthesis methods suffer from slow processes, large batch-to-batch variability, and low product purity; and commonly used chemically synthesized surfactant templates may introduce bioincompatible components, limiting their application.

[0004] Therefore, developing a novel green preparation process for selenium nanoparticles that is safe in raw materials, green in process, produces high-performance products, and is easy to industrialize is of urgent need and great significance for promoting its widespread application. In view of this, this invention proposes a method for preparing selenium nanoparticles and the same. Compared to the reduction method, which relies on highly toxic sodium selenite as a precursor, this method uses selenourea as the selenium source, resulting in lower toxicity and significantly reducing safety risks and subsequent environmental burden during synthesis. Furthermore, oxygen is used as a green oxidant, with water as the only byproduct, achieving a clean reaction process. The endogenous bile salt sodium deoxycholate (NaDC) serves as a stabilizer, ensuring the product itself is biocompatible and biodegradable, thus avoiding the residual toxicity risks associated with chemical stabilizers. Summary of the Invention

[0005] The purpose of this invention is to provide selenium nanoparticles and their preparation method, so as to solve the problems of toxicity risk and poor biocompatibility of existing preparation methods.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a selenium nanoparticle, which is a NaDC micelle-stabilized selenium nanoparticle.

[0007] Furthermore, the selenium nanoparticles are spherical with a particle size of 50~150nm.

[0008] An oxidation preparation method for selenium nanoparticles involves introducing oxygen into an alkaline mixed solution containing selenourea and NaDC to carry out a reaction, thereby obtaining the selenium nanoparticles.

[0009] Furthermore, the pH of the alkaline mixed solution was adjusted using a 1M sodium hydroxide solution.

[0010] Further, take 0.8g of sodium hydroxide solid, add 20mL of water, shake to dissolve it completely, and obtain a 1mol / L sodium hydroxide solution.

[0011] Furthermore, in the alkaline mixed solution, NaDC is in a micelle state.

[0012] Furthermore, an alkaline mixed solution can be obtained by mixing an alkaline solution of NaDC with selenourea, or by mixing NaDC with selenourea and then adjusting the pH to alkaline.

[0013] Furthermore, the water is deionized water.

[0014] Furthermore, the pH of the alkaline mixed solution is 12.

[0015] Furthermore, the NaDC powder has a mass of 66.33~331.65 mg.

[0016] Furthermore, the mass of the selenourea powder is 1.23~98.42 mg.

[0017] Furthermore, the molar ratio of selenourea to NaDC in the alkaline mixed solution is 1:1 to 1:16.

[0018] Further, a magnetic stir bar was added, the bottle opening was sealed with sealing film, several holes were poked to maintain air circulation and ensure sufficient oxygen, and the bottle was placed on a magnetic stirrer and stirred at a speed of 200~400 r / min to prepare selenium nanoparticles.

[0019] Furthermore, the stirring time is 0~48h.

[0020] Furthermore, the reaction temperature is 20~40℃.

[0021] The beneficial effects of this invention are: 1. The method of the present invention uses selenourea as a selenium source, which has a much lower toxicity than sodium selenite, greatly reducing the safety risks in the synthesis process and the subsequent environmental burden; 2. The method of the present invention uses NaDC to prepare micelles. NaDC is a natural endogenous bile salt with high biocompatibility and safety for humans and animals. It is itself a part of the organism, is easily biodegradable, and has no residual toxicity. 3. The method of this invention uses oxygen as a green oxidant, and the byproduct is water. The process is clean, making the final product very suitable for agricultural production, animal husbandry development and biomedical fields. 4. The method and product system of this invention are simple, the product quality is stable, the size is uniform and the dispersion is good, and it can be directly stored and used, and has broad application prospects. Attached Figure Description

[0022] Figure 1 This is a graph showing the intensity ratio of the characteristic fluorescence emission peaks of pyrene molecules in NaDC solutions of different concentrations in Example 1 of the present invention. Figure 2 This refers to the change in the UV characteristic peak value at the initial stage of the reaction of the selenium nanoparticle preparation solution in Example 2 of this invention; Figure 3 This is a graph showing the color change of the solution used to prepare selenium nanoparticles in Example 3 of this invention over reaction time. Figure 4 This is a transmission electron microscope image of the selenium nanoparticle product obtained in Example 3 of this invention. Figure 5 The particle size distribution of the selenium nanoparticle product obtained in Example 3 of this invention was measured by a dynamic light scattering instrument. Figure 6 This is a transmission electron microscope image of the selenium nanoparticle product obtained from the reaction in Example 4 of this invention. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0024] The principle of synthesizing selenium nanoparticles in this invention is as follows: In alkaline aqueous solution, selenourea first undergoes hydrolysis, breaking the carbon-selenium bond to generate hydrogen selenide (H₂Se) or hydrogen selenide ions (HSe), which have strong reducing properties. - Meanwhile, the introduced oxygen acts as a green oxidant, reacting with these reducing selenium species in a redox reaction to convert them into zero-valent selenium atoms (Se).

[0025] Because elemental selenium has extremely low solubility in the aqueous phase, newly generated Se atoms will rapidly aggregate to form crystal nuclei. At this point, NaDC in the solution plays a crucial role. When its concentration exceeds the critical micelle concentration (CMC), it will self-assemble to form micelles with hydrophobic cores. These micelles act as nanoreactors, effectively capturing and confining the newly generated selenium nuclei through hydrophobic interactions, inhibiting their disordered growth and aggregation, and guiding the orderly deposition of selenium atoms to generate uniformly sized nanoparticles.

[0026] Meanwhile, NaDC molecules extend outward into the aqueous phase through their hydrophilic groups to form a steric hindrance layer, ultimately obtaining a stable and biocompatible colloidal solution of selenium nanoparticles. This process essentially combines the reducing properties of selenourea with the oxidizing properties of oxygen under the regulation of a biosurfactant template, achieving the green and controllable synthesis of selenium nanoparticles.

[0027] Example 1 In this embodiment, the critical concentration of NaDC for micelle formation is determined by the following steps: S1. Dissolve 3.03 mg of pyrene in 10 mL of acetone to obtain a 1.5 mM pyrene solution. Transfer 100 μL of this solution to a 500 mL Erlenmeyer flask using a pipette, and add 500 mL of ultrapure water to obtain a 0.3 μM pyrene solution. Adjust the pH of the pyrene solution to 12.

[0028] S2. Take 250 mL of S1 pyrene solution (0.3 μM, pH 12), weigh 2.073 g of NaDC powder and dissolve it to obtain a mixed solution containing 20 mM NaDC and 0.3 μM pyrene.

[0029] S3. Use a pipette to take 1-20 mL (round to the nearest integer) of the mixed solution from S2 into sample vials, and dilute to 20 mL with the 0.3 μM pyrene solution from S1 to obtain 1-20 mM NaDC solutions containing 0.3 μM pyrene, and label them as group 1 to group 20 respectively.

[0030] S4. Add the 20 solutions from S3 to quartz dishes respectively, and use a fluorescence spectrophotometer to detect them. Look for the characteristic fluorescence emission peaks I3 and I1 of pyrene molecules, calculate I3 / I1, and plot the critical micelle concentration of NaDC.

[0031] Depend on Figure 1As shown, at lower NaDC concentrations, the I3 / I1 ratio does not change significantly with increasing NaDC concentration. A clear inflection point appears at 4 mM, and the I3 / I1 ratio increases rapidly with further increases in NaDC concentration, then stabilizes. Since the NaDC solution concentration approaches the critical micelle concentration, the bile salts assemble into micelles with hydrophobic cores that can accommodate hydrophobic pyrene molecules. When the polarity of the pyrene molecule's environment changes, its characteristic signal I3 / I1 increases. Therefore, the concentration corresponding to this inflection point is denoted as the critical micelle concentration. Thus, the critical micelle concentration of NaDC at pH=12 is 4 mM.

[0032] Example 2 In this embodiment, the change in the ultraviolet characteristic peak at the initial stage of the reaction is measured, and the steps are as follows: S1. Take 0.8g of sodium hydroxide solid, add 20mL of water, shake to dissolve it completely, and obtain a 1mol / L sodium hydroxide solution.

[0033] S2. Take 66.33 mg of NaDC powder into a round-bottom flask, add 40 mL of ultrapure water, and sonicate to dissolve it completely.

[0034] S3. Using an acid-base tester to measure the solution, add 10 drops of 1M sodium hydroxide solution to obtain an alkaline solution with pH=12, i.e., a 4mM NaDC solution.

[0035] S4. Add 2.46 mg of selenourea powder to a 4 mM NaDC solution to obtain an alkaline mixed solution containing 0.5 mM selenourea and 4 mM NaDC.

[0036] S5. Add the magnetic stir bar, seal the bottle opening with sealing film, poke several holes to keep the air flowing and ensure sufficient oxygen, and place it on a magnetic stirrer to stir at a speed of 300 r / min.

[0037] S6. Record the time: at 0h, 1h, 2h, and 4h, take 0.5mL of sample into a quartz dish, add 2.5mL of ultrapure water, and monitor the reaction under a UV-Vis spectrophotometer.

[0038] Depend on Figure 2 As shown, when the reaction proceeds from 0h to 4h, the peak values ​​of the two peaks show a decreasing trend, thus proving that the reaction has started and the raw materials have been consumed.

[0039] Example 3 In this embodiment, NaDC micelles are first formed, and then selenourea is added. The molar ratio of selenourea to NaDC is 1:8. The synthesis steps of selenium nanoparticles are as follows: S1. Dissolve 66.33 mg of NaDC powder in 40 mL of ultrapure water to obtain a 4 mM NaDC solution.

[0040] S2. Add the prepared 1M sodium hydroxide solution to the solution obtained in S1, and use an acid-base tester to control the pH to 12.

[0041] S3. Add 2.46 mg of selenourea powder to the solution obtained in S2 to obtain a solution with a selenourea to NaDC concentration ratio of 1:8.

[0042] S4. Add the magnetic stir bar, seal the bottle opening with sealing film, poke several holes, place it on a magnetic stirrer and stir at 300 r / min for 24 hours.

[0043] like Figure 3 As shown, the solution color gradually deepens with the extension of reaction time, indicating that the reaction continues.

[0044] like Figure 4 As shown, well-shaped and well-dispersed selenium nanoparticles can be observed under a transmission electron microscope, and the selenium nanoparticles are spherical.

[0045] like Figure 5 As shown, under the detection of a dynamic light scattering instrument, the selenium nanoparticles are uniform in size and well dispersed, with a particle size distribution of 50~150nm.

[0046] Example 4 In this embodiment, selenourea and NaDC are first mixed, and then the pH is adjusted to form NaDC micelles. The molar ratio of selenourea to NaDC is 1:8. The synthesis steps of selenium nanoparticles are as follows: S1. Dissolve 2.46 mg of selenourea powder in 40 mL of ultrapure water to obtain a 0.5 mM selenourea solution.

[0047] S2. Add 66.33 mg of NaDC powder to the solution obtained in S1. After dissolving, a solution with a molar ratio of 1:8 between selenourea and NaDC is obtained.

[0048] S3. Add the prepared 1M sodium hydroxide solution to the solution obtained in S2, and use an acid-base tester to control the pH to 12.

[0049] S4. Add the magnetic stir bar, seal the bottle opening with sealing film, poke several holes, place it on a magnetic stirrer and stir at 300 r / min for 24 hours.

[0050] like Figure 6 As shown, well-shaped and well-dispersed selenium nanoparticles can be observed under a transmission electron microscope, and the selenium nanoparticles are spherical.

[0051] In summary, the selenium nanoparticles of the present invention are easy to prepare, have uniform size, good dispersibility, and strong biocompatibility, and are expected to be applied in agricultural production, animal husbandry development, and the biomedical field.

[0052] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A selenium nanoparticle, characterized in that: The selenium nanoparticles are sodium deoxycholate micelle-stabilized selenium nanoparticles.

2. The selenium nanoparticle of claim 1, wherein: The sodium deoxycholate micelle is a sodium deoxycholate alkaline solution with a concentration not less than a critical concentration capable of forming micelles under the alkaline condition.

3. The selenium nanoparticle of claim 2, wherein: The critical concentration of sodium deoxycholate solution forming micelles is 4 mM when the pH is 12.

4. The selenium nanoparticle of claim 1, wherein: The particle size of the selenium nanoparticles is 50-150 nm.

5. A method for determining the critical micelle concentration of a sodium deoxycholate solution, characterized by: The characteristic fluorescence emission peaks I3 and I1 of pyrene molecules with a certain concentration in sodium deoxycholate alkaline solutions with different concentrations and the same pH value are determined, I3 / I1 is calculated respectively, the curve of the characteristic signal I3 / I1 changing with the concentration of sodium deoxycholate alkaline solution is drawn, and the concentration corresponding to the turning point of the characteristic signal I3 / I1 is recorded as the critical micelle concentration.

6. A method of preparing selenium nanoparticles, characterized by: Selenium urea reacts with oxygen under the external environmental conditions of sodium deoxycholate solution reaching the critical micelle concentration to obtain the sodium deoxycholate micelle-stabilized selenium nanoparticles of the application.

7. The method for preparing selenium nanoparticles according to claim 6, characterized in that: The concentration of sodium deoxycholate solution forming micelles is 4-20 mM when the pH of the sodium deoxycholate solution is 12.

8. The method for preparing selenium nanoparticles according to claim 6, characterized in that: The molar concentration ratio of selenium urea to sodium deoxycholate is 1:1-16.

9. The method for preparing selenium nanoparticles according to claim 6, characterized in that: The source of oxygen includes direct contact of the solution with air and utilization of oxygen in the air.

10. The method for preparing selenium nanoparticles according to claim 6, characterized in that: The reaction temperature is 20-40℃, the reaction time is 0-48 h, and the stirring intensity is 200-400 r / min.

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