Preparation method and application of sodium alginate functionalized nano-selenium

Abstract

The invention relates to the technical field of biological nano-materials, in particular to a preparation method and application of sodium alginate functionalized nano-selenium, and the preparation method comprises the following steps: step 1, uniformly mixing sodium selenite and a sodium alginate solution, and then slowly adding an ascorbic acid solution to form a reaction system; stirring with a magnetic stirrer at a constant temperature and a constant speed at regular time, and reacting for a period of time to obtain an alginic acid nano-selenium solution; 2, optimizing experimental reaction conditions in the step 1 by adopting a dual-wavelength method, and determining optimal reaction conditions by changing the solubility of a sodium alginate solution, the concentration ratio of ascorbic acid to sodium selenite and reaction time to obtain a reaction solution; and step 3, performing dialysis treatment on the reaction solution in the step 2, and performing freeze drying to obtain the alginic acid nano-selenium. According to the invention, a dual-wavelength method is adopted to optimize reaction conditions, the synthesis method is simple, the raw material source is rich, and the prepared polysaccharide nano-selenium has the characteristics of good stability, strong oxidation resistance, high selenium content and good dispersibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological nanomaterials, and particularly relates to a preparation method of sodium alginate functionalized nano selenium and application thereof. BACKGROUND

[0002] Selenium (Se) is an essential trace element for human body and plays a vital role in human health. According to research, selenium is the main component of many enzymes, including glutathione peroxidase (GPx), superoxide dismutase (SOD), thioredoxin reductase (TXNRD) and thyroid deiodinase (DIO). These enzymes play a vital role in antioxidant, reproductive system, liver protection function and tumor prevention. However, selenium cannot be synthesized autonomously in the human body and must be taken from food, and various diseases in the human body, such as dilated cardiomyopathy-Keshan disease, atherosclerosis, ischemic heart disease, hypertension, diabetes, etc. are related to selenium deficiency.

[0003] Selenium mainly exists in the form of organic / inorganic in nature. The main form of organic selenium is selenoamino acid, selenide polysaccharide. The main form of inorganic selenium is selenate, selenite, metal selenide, elemental selenium. Compared with inorganic selenium compounds, organic selenium compounds have the advantages of higher bioavailability and lower toxicity. It has the potential to be a new nutritional supplement. However, due to the small gap between the effective dose and the toxic dose of selenium-containing compounds as dietary supplements, their bioavailability and biological activity have been greatly limited. In recent years, more and more studies have shown that red nano selenium (SeNPs) has lower toxicity (its toxicity is only one seventh of inorganic selenium or one third of organic selenium) and higher bioavailability. Due to its high surface energy, it is easy to aggregate, and the chemical reduction method in the presence of dispersants or stabilizers provides an excellent method for preparing nano selenium.

[0004] Sodium alginate (SA) is a natural anionic polysaccharide composed of β-1,4-D-mannuronic acid (M) and α-1,4-L-guluronic acid (G) homopolymer units. It is mainly extracted from kelp, horsetail, large algae and conidial algae in the ocean, and has become the largest seaweed chemical raw material. It has the characteristics of low cost, non-toxicity, biodegradability and good biocompatibility, and is widely used in food, pharmaceutical and cosmetic industries. Sodium alginate contains a large number of hydroxyl and carboxyl groups, and exists in the form of a polyion with multiple negative charges in water after being dissolved in water. The microenvironment formed has good suspension, emulsification and stability, and is very suitable for being used as a stabilizer to prepare nanomaterials. At present, researchers have successfully prepared stable nano silver particles, iron sulfide nanoparticles, amorphous calcium carbonate nanoparticles, etc. using sodium alginate as a stabilizer. Therefore, using sodium alginate as a nano selenium modifier is a better choice.

[0005] Chinese patent CN115651087A discloses a method for preparing nano-selenium, which uses ascorbic acid as a reducing agent, sodium selenite as a selenogen, and Enteromorpha polysaccharide as a stabilizer. Active nano-selenium with a nanoparticle size of about 60nm and liver-protecting function is prepared. Chinese patent CN116589603A discloses a method for preparing Morinda officinalis polysaccharide nano-selenium. The synthesized Morinda officinalis polysaccharide nano-selenium has the activity of inhibiting various tumor cells and has low toxic side effects on normal cells. Chinese patent CN113980149A discloses a method for preparing Huoshan Dendrobium polysaccharide nano-selenium. Compared with Huoshan Dendrobium polysaccharide, Huoshan Dendrobium polysaccharide nano-selenium has significantly enhanced antioxidant properties. At present, there are no reports on the preparation method and application of sodium alginate functionalized nano-selenium complexes. Summary of the Invention

[0006] The purpose of the present invention is to solve the shortcomings of the existing technology and propose a preparation method and application of sodium alginate functionalized nano-selenium. The dual-wavelength method is used to optimize the reaction conditions. The synthesis method is simple and the raw material source is abundant. The prepared polysaccharide nano-selenium has the characteristics of good stability, high selenium content and good dispersibility.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing sodium alginate functionalized nano-selenium comprises the following steps:

[0009] Step 1: Mix sodium selenite and sodium alginate solution evenly, then slowly add ascorbic acid solution to form a reaction system; stir with a magnetic stirrer at a constant temperature, timing and speed, and react for a period of time to obtain an alginate nano-selenium solution;

[0010] Step 2: The reaction conditions of the experiment in step 1 were optimized using a dual-wavelength method. The optimal reaction conditions were determined by changing the solubility of the sodium alginate solution (0, 100, 200, 300, 400 mg / L), the concentration ratio of ascorbic acid to sodium selenite (1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1), and the reaction time (30, 60, 90, 120, 150 min) to obtain a reaction solution.

[0011] Step 3: The reaction solution in step 2 is dialyzed and freeze-dried to obtain alginate nano-selenium.

[0012] Preferably, in step 2, the concentration of sodium selenite is 0.05 mol / L.

[0013] Preferably, in step 2, the solubility of the sodium alginate solution is 0-400 mg / L.

[0014] Preferably, in step 2, the solubility of the ascorbic acid solution is 0-0.4 mol / L.

[0015] Preferably, in step 2, the concentration ratio of ascorbic acid to sodium selenite is 1-8:1.

[0016] Preferably, in step 2, the reaction time is 30-150 min.

[0017] Preferably, in step 3, the molecular weight cut-off of the dialysis bag used for the dialysis treatment is 14000D, and the dialysis treatment time is 48-72h.

[0018] Preferably, the preparation time of the above-mentioned alginate nano-selenium is 90 minutes, the selected sodium alginate concentration is 200 mg / L, and the concentration ratio of sodium selenite to ascorbic acid is 1:6.

[0019] Preferably, in the above-mentioned method for preparing alginate nano-selenium, the selected sodium alginate concentration is 200 mg / L, the concentration ratio of sodium selenite to ascorbic acid is 1:6, and the preparation time is 60 minutes.

[0020] The present invention also provides alginate nano-selenium obtained by the above preparation method. The alginate nano-selenium is a spherical amorphous material with a particle size of about 75 nm and a selenium content of 70-80%.

[0021] The present invention also provides a use of alginate nano-selenium obtained by the above-mentioned preparation method in in vitro antioxidant performance determination.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a method for preparing alginate nano-selenium via a green synthesis reaction using sodium selenite and ascorbic acid as raw materials and sodium alginate as a stabilizer. The preparation process is simple, the required experimental raw materials are abundant, and the resulting material has a high selenium content. The prepared alginate nano-selenium is uniformly dispersed in the form of spheres with a particle size of approximately 75 nm and a selenium content of 70-80%.

[0024] 2. Compared with green, monodispersed nano-selenium synthesized by adding sodium alginate as a stabilizer, the alginate nano-selenium synthesized in this invention has good stability and can be stable for at least 30 days at 4°C. In terms of antioxidant properties, alginate nano-selenium exhibits excellent antioxidant properties.

[0025] 3. The present invention uses a dual-wavelength method to optimize the reaction conditions. Its synthesis method is simple and the raw material source is abundant. The prepared polysaccharide nano-selenium has the characteristics of good stability, high selenium content, good dispersibility and good antioxidant performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the alginate nano-selenium solution and the nano-selenium solution after being placed for 24 hours;

[0027] Figure 2 The present invention is a spectrum analysis diagram; A is a UV spectrum analysis diagram of alginate nano-selenium, sodium alginate, a mixed solution of sodium alginate and ascorbic acid, ascorbic acid, and a nano-selenium solution; B is a diagram showing the effect of sodium alginate dosage on light absorption; C is the effect of the concentration ratio of sodium selenite and ascorbic acid on light absorption; D is a diagram showing the effect of different reaction times on light absorption;

[0028] Figure 3 The particle size distribution diagram of the present invention; A is a particle size distribution diagram of a nano-selenium solution without the addition of sodium alginate using dynamic light scattering analysis; B is a particle size distribution diagram of a nano-selenium solution with the addition of sodium alginate using dynamic light scattering analysis;

[0029] Figure 4 The images of the nano-selenium solution of the present invention are as follows; A is an image of the nano-selenium solution without sodium alginate taken using a transmission electron microscope; B is an image of the nano-selenium solution with sodium alginate taken using a transmission electron microscope;

[0030] Figure 5 This is a schematic diagram of analyzing the selenium content in alginate nano-selenium using an energy spectrometer in the present invention;

[0031] Figure 6 is the X-ray diffraction pattern of alginate nano-selenium of the present invention;

[0032] Figure 7 This is the infrared spectrum of sodium alginate and alginate nano-selenium of the present invention;

[0033] Figure 8 This is a comparison of the DPPH free radical scavenging abilities of alginate nano-selenium, sodium alginate, sodium selenite, and ascorbic acid according to the present invention;

[0034] Figure 9 This is a comparison chart of the ABTS free radical scavenging abilities of alginate nano-selenium, sodium alginate, sodium selenite and ascorbic acid according to the present invention. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings so that those skilled in the art can better understand the advantages and features of the present invention and thus more clearly define the scope of protection of the present invention. The embodiments described in the present invention are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, all reagents used in the examples can be purchased from the market.

[0037] Freshly prepare 250 mL of sodium alginate solution (1000 mg / L), 200 mL of ascorbic acid (0.1 M), and 100 mL of sodium selenite (0.05 M) using deionized water.

[0038] Example 1: Preparation of Nano-Selenium

[0039] Add a certain amount of sodium selenite solution and deionized water to a 250mL conical flask and stir for 5 minutes. Then slowly add the freshly prepared vitamin C solution dropwise and react at room temperature for 2 hours. After the reaction is complete, a nano-selenium solution is formed.

[0040] Example 2: Preparation of Alginate Nano-Selenium

[0041] Under magnetic stirring, a certain amount of sodium alginate solution and sodium selenite solution were added to a 250 mL conical flask. After mixing thoroughly, deionized water was added and stirred for 5 minutes. Freshly prepared ascorbic acid solution was then slowly added dropwise and allowed to react at room temperature for 2 hours. After the reaction, an alginate nano-selenium solution was formed.

[0042] Depend on Figure 1 It can be seen that the nano-selenium solution without sodium alginate precipitated after 24 hours, indicating poor stability. The nano-selenium solution with sodium alginate remained clear and transparent after 24 hours.

[0043] Example 3: Optimization of experimental conditions using the dual-wavelength method

[0044] UV-visible spectroscopy was used for analysis. Figure 2 As shown in Figure A, sodium alginate has no obvious absorption peak in the 200-600nm range, while ascorbic acid has a maximum absorption peak at 287nm. The mixed solution of ascorbic acid and sodium alginate has a maximum absorption peak at 286nm. Nano-selenium and alginate nano-selenium have maximum absorption peaks at 290nm, but nano-selenium has no absorption in the 300-600nm range, while alginate nano-selenium has significant absorption in the 300-600nm range. These results indicate that sodium alginate and nano-selenium interact with each other and form alginate nano-selenium.

[0045] Based on the UV-visible spectroscopy results, the present invention uses dual-wavelength colorimetry to simply optimize the reaction conditions. According to the dual-wavelength method for colloidal solutions, the colloidal particle size parameter B = 1g (A2 / A1) / 1g (λ1 / λ2). Here, A1 and A2 are the absorbances at wavelengths λ1 and λ2, respectively. This formula shows that when the wavelengths λ1 and λ2 are fixed and the absorbance ratio A2 / A1 remains constant, the colloidal particle size remains constant, indicating a stable state. To avoid absorption by ascorbic acid and facilitate measurement, the visible wavelengths of 410nm and 490nm were selected.

[0046] Effect of polysaccharide concentration on nanoparticle size

[0047] Set five gradients of sodium alginate solution concentration (0, 100, 200, 300, 400 mg / L), and other conditions are: sodium selenite concentration is 0.005M, ascorbic acid concentration is 0.02M, and the time is 90 minutes. Figure 2 As shown in B, it can be seen that within a certain range, A 410 / A 490 The value increases with increasing sodium alginate concentration and remains essentially stable within the sodium alginate concentration range of 200-400 mg / L, indicating that the nano-selenium particles prepared within this range are uniform and stable. Considering factors such as the particle size and stability of nano-selenium, a sodium alginate solution concentration of 200 mg / L was selected as the optimal concentration for preparing nano-selenium.

[0048] Effect of the concentration ratio of ascorbic acid to sodium selenite on the size of nanoparticles

[0049] Set eight gradients of ascorbic acid to sodium selenite concentration ratios (1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1), and other conditions: sodium alginate solution concentration of 200 mg / L, time of 90 min. Figure 2 As shown in C, it can be seen that as the concentration ratio of ascorbic acid to sodium selenite increases, A 410 / A 490 The value also increases, reaches the maximum ratio of 6:1 and then tends to be stable. This shows that the nano-selenium prepared under this condition is relatively stable and uniform.

[0050] Effect of reaction time on nanoparticle size

[0051] Five gradient reaction times (30, 60, 90, 120, and 150 min) were set, and other conditions were as follows: the concentration of sodium alginate solution was 200 mg / L, and the ratio of ascorbic acid to sodium selenite was 6:1. Figure 2 As shown in D, it can be seen that time has little effect on the formation of nanoparticles. 410 / A 490The value is basically stable at around 1.70, with a maximum value at 60 minutes, and then tends to be stable.

[0052] After examining various factors, the optimal process was determined: a sodium alginate concentration of 200 mg / L, an ascorbic acid to sodium selenite ratio of 6:1, and a reaction time of 60 minutes. Under these optimal conditions, the reaction solution was dialyzed (MW = 14,000D) for two days and then freeze-dried using a freeze dryer. This yielded the desired alginate nanoselenium complex, which was then prepared for subsequent performance testing.

[0053] Size is an important factor in defining nanoparticles. Figure 3 A shows the particle size distribution in the solution without sodium alginate added, and the results show that the average nanoparticle size of the bare nanoparticles is 725.5±6.4nm. Figure 3 As shown in Figure B, compared with the solution without sodium alginate, the average nanoparticle size of alginate nanoselenium is 144.0±1.8nm. It can be seen that sodium alginate, as a stabilizer and dispersant, can effectively reduce the nanoparticle size of the nanoparticle solution.

[0054] Figure 4 A is the transmission electron microscopy image of nano-selenium. The results show that when no stabilizer is added, nano-selenium is easy to aggregate and has an irregular shape. The transmission electron microscopy image of alginate nano-selenium prepared under the optimal conditions is shown in Figure 1. Figure 4 As shown in Figure B, it can be clearly seen that under the action of sodium alginate, the nano-selenium exhibits a monodisperse, uniform spherical structure with an average particle size of approximately 75nm. This result is similar in size and morphology to SeNPs prepared from Radix Isatidis and Spirulina polysaccharides (70–80nm) and Schisandra chinensis polysaccharides (120nm).

[0055] Figure 5 The following is a surface elemental spectrum analysis of alginate nanoselenium. As can be seen from the figure, the weight percentage of selenium atoms in the alginate nanoselenium is 70.65%, carbon atoms are 25.50%, and oxygen atoms are 3.85%. This result demonstrates that selenium has been successfully incorporated into the polysaccharide matrix and that alginate nanoselenium has been successfully synthesized in the presence of sodium alginate. Furthermore, few significant absorption peaks for other elements were observed, demonstrating the purity of the alginate nanoselenium.

[0056] Figure 6 The X-ray diffraction pattern of alginate nano-selenium is shown in Figure 2. The trigonal structure of selenium has two strong and sharp reflection peaks at 2θ of 24° and 30°, which is crystalline selenium. Figure 6 In addition to showing a broad peak at 2θ=20-30°, alginate nano-selenium does not have a sharp Bragg reflection, indicating that the synthesized alginate nano-selenium is amorphous rather than a crystalline structure.

[0057] Figure 7 The infrared spectra of sodium alginate and alginate nano-selenium. Figure 7 As shown in Figure 2, the infrared spectrum of alginate nano-selenium is similar to that of sodium alginate, which confirms that the assembly between nano-selenium and sodium alginate is through intermolecular forces rather than the generation of new chemical bonds. The infrared spectrum of sodium alginate is at 3418.95 cm -1 The peak at 2932.13 cm represents the OH stretching vibration. -1 The peak at represents the stretching vibration of CH. In the infrared spectrum of alginate nanoselenium, the OH stretching vibration ranges from 3418.95 cm -1 Move to 3218.30cm -1 , indicating that there is a hydrogen bond between nano-selenium and the OH group of sodium alginate. The stretching vibration of CH is slightly shifted to 2932.23 cm -1 1609.51cm -1 The peak at is the CO2 in the infrared spectrum of sodium alginate - (Carboxylate ion) group stretching vibration, 1416.76 cm -1 The peaks around are attributed to the deformation vibration of hydroxyl groups, and the absorption peak at 1092.17cm-1 is the COC stretching vibration of the glycosidic bond. In the infrared spectrum of alginate nanoselenium, CO2 - The value is offset to 1596.21cm -1 , 1416.76cm -1 The peak shifted to 1413.57 cm -1 The results showed that the carboxyl and hydroxyl groups of sodium alginate participated in the synthesis and stabilization of nano-selenium, and nano-selenium may be combined with sodium alginate through hydrogen bonds (OH⋯Se).

[0058] Example 4: Determination of antioxidant activity of different samples

[0059] DPPH free radical scavenging experiment

[0060] DPPH (1,1-diphenyl-2-picrylhydrazyl) is a stable purple free radical that is reduced by antioxidant molecules by accepting electrons or hydrogen, resulting in a yellowish color after its solution is scavenged. Sodium alginate, ascorbic acid, sodium selenite, and alginate nanoselenium powder were weighed and dissolved in deionized water to prepare sample solutions with a concentration gradient (0.06, 0.13, 0.20, 0.26, and 0.33 mg / mL). 5 mg of DPPH solid was dissolved in 125 mL of methanol, wrapped in aluminum foil, and stored in the dark. Ultrasonication was performed for 5 minutes, followed by thorough shaking to homogenize the upper and lower portions. 1 mL of SA-SeNPs nanocomposite solutions of varying concentrations was mixed with 2 mL of DPPH methanol solution. The mixture was incubated in a 37°C oven for 30 minutes, and the absorbance at 519 nm was measured using a UV-visible spectrophotometer. An equal volume of deionized water was used in place of the sample solution as a blank control, and an equal volume of anhydrous ethanol solution was used in place of the DPPH solution as a sample control.

[0061] Figure 8 The DPPH free radical scavenging ability of sodium alginate, ascorbic acid, and alginate nanoselenium was demonstrated, using ascorbic acid as a positive control. The results showed that within the 0-0.33 mg / mL range, the DPPH scavenging rate of alginate nanoselenium increased linearly with concentration. At a concentration of 0.33 mg / mL, alginate nanoselenium's DPPH free radical scavenging ability reached 82.9%, but this was lower than that of ascorbic acid. The DPPH scavenging rates of sodium alginate and sodium selenite did not exceed 20% within the 0-0.33 mg / mL range, demonstrating relatively low DPPH free radical scavenging abilities.

[0062] ABTS free radical scavenging assay

[0063] Sodium alginate, ascorbic acid, sodium selenite, and alginate nanoselenium powder were weighed and dissolved in deionized water to prepare sample solutions with a concentration gradient (0.06, 0.13, 0.20, 0.26, and 0.33 mg / mL). A 7.4 mM ABTS stock solution and a 2.6 mM K2S2O8 solution were prepared, and 2 mL of each solution was mixed in equal volumes. The mixture was then incubated in the dark for 12 hours to obtain a stable ABTS working solution. Prior to working, the working solution was diluted with deionized water to an absorbance of 0.700 ± 0.002 at 734 nm. Then, 1 mL of the alginate nanoselenium solution of varying concentrations (0.06-0.33 mg / mL) was mixed with 2 mL of the diluted ABTS solution. After mixing thoroughly, the mixture was incubated in the dark for 6 minutes. The absorbance at 734 nm was measured using a UV-visible spectrophotometer. An equal volume of deionized water was used to replace the sample solution as a blank control, and an equal volume of deionized water was used to replace the ABTS solution as a sample control.

[0064] The scavenging of DPPH radicals involves hydrogen atom transfer, while the scavenging of ABTS radicals involves electron transfer process and has higher reactivity. Figure 9 The results show that sodium alginate, sodium selenite and alginate nano-selenium have the ability to scavenge ABTS free radicals, with ascorbic acid as the positive control. Compared with DPPH, alginate nano-selenium has a stronger scavenging effect on ABTS free radicals. The scavenging rate of alginate nano-selenium gradually increases with the increase of concentration. When the concentration is 0.33 mg / mL, the scavenging rate reaches 92.3%, which is significantly stronger than sodium alginate and sodium selenite, but lower than ascorbic acid. Sodium alginate has a strong scavenging effect on ABTS- + Almost no impact.

[0065] In summary, the present invention uses the dual-wavelength method to optimize the reaction conditions. The synthesis method is simple and the raw material sources are abundant. The prepared polysaccharide nano-selenium has the characteristics of good stability, high selenium content and good dispersibility.

[0066] The descriptions and practices disclosed in this invention are easy to understand and comprehend for those skilled in the art, and modifications and refinements may be made without departing from the principles of the invention. Therefore, modifications and improvements made without departing from the spirit of the invention should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing sodium alginate functionalized nano-selenium, characterized in that: The steps include: Step 1: Mix sodium selenite and sodium alginate solution evenly, then slowly add ascorbic acid solution to form a reaction system; stir with a magnetic stirrer at a constant temperature, timing and speed, and react for a period of time to obtain an alginate nano-selenium solution; Step 2: Optimizing the reaction conditions of the experiment in step 1 by using a dual-wavelength method, determining the optimal reaction conditions by changing the solubility of the sodium alginate solution, the concentration ratio of ascorbic acid to sodium selenite, and the reaction time, and obtaining a reaction solution; Step 3: The reaction solution in step 2 is dialyzed and freeze-dried to obtain alginate nano-selenium.

2. The method for preparing nano-selenium alginate according to claim 1, wherein: In step 2, the concentration of sodium selenite is 0.05 mol / L.

3. The method for preparing sodium alginate functionalized nano-selenium according to claim 1, wherein: In step 2, the solubility of the sodium alginate solution is 0-400 mg / L.

4. The method for preparing sodium alginate functionalized nano-selenium according to claim 1, wherein: In step 2, the solubility of the ascorbic acid solution is 0-0.4 mol / L.

5. The method for preparing sodium alginate functionalized nano-selenium according to claim 1, wherein: In step 2, the concentration ratio of ascorbic acid to sodium selenite is 1-8:

1.

6. The method for preparing sodium alginate functionalized nano-selenium according to claim 1, wherein: In step 2, the reaction time is 30-150 min.

7. The method for preparing sodium alginate functionalized nano-selenium according to claim 1, characterized in that: In step 3, the dialysis bag used for dialysis treatment has a molecular weight cut-off of 14000D, and the dialysis treatment time is 48-72h.

8. Alginate nano-selenium obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The alginate nano-selenium is a spherical amorphous material with a particle size of 75 nm, and the selenium content of the alginate nano-selenium is 70-80%.

9. Use of alginate nano-selenium obtained by the preparation method according to any one of claims 1 to 7 in in vitro antioxidant performance determination.

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