Preparation method of astaxanthin nanoparticles

Abstract

The invention discloses a preparation method of astaxanthin nanoparticles, and belongs to the field of novel functional materials. The method comprises the following steps: (a) preparing an amphiphilic gamma-polyglutamic acid derivative; and (b) preparation of the astaxanthin nanoparticles. The astaxanthin nanoparticles are prepared by selecting hydrophilic biomacromolecule gamma-PGA as a carrier and utilizing a macromolecule self-assembly principle, so that the stability and the water solubility of the astaxanthin are effectively improved, the problems that the astaxanthin is easy to oxidize, unstable in property, poor in water solubility and the like are effectively solved, the utilization degree of the astaxanthin is greatly improved, and the astaxanthin nanoparticles are suitable for large-scale production. And the selected carrier material is gamma-PGA, has good biocompatibility and degradability, and is safe and non-toxic.

Description

Technical Field

[0001] The invention relates to a method for preparing astaxanthin nanoparticles, and belongs to the field of new functional materials. Background Art

[0002] Astaxanthin (AST), or 3,3'-dihydroxy-β,B'-carotene-4,4'-dione, is a fat-soluble carotenoid with multiple biological activities such as anti-aging, anti-inflammatory, antioxidant, and anti-cancer. It has broad application prospects in health products, medicine, cosmetics, food additives, and aquaculture. Although astaxanthin has attracted much attention due to its multiple biological functions, its poor water solubility, strong hydrophobicity, high melting point, and poor chemical stability have a significant impact on its transfer efficiency, resulting in low utilization and limiting its application. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing astaxanthin nanoparticles, which improves the stability and water solubility of astaxanthin. The prepared astaxanthin particles also have high permeability and sustained release, greatly improving the utilization of astaxanthin. In order to solve the above technical problems, the technical solution provided by the present invention is: A method for preparing astaxanthin nanoparticles comprises the following steps: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) dissolving γ-polyglutamic acid (γ-PGA) in a NaHCO3 aqueous solution and stirring until fully dissolved to obtain a γ-PGA aqueous solution; (a2) adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and a hydrophobic small molecule L-phenylalanine ethyl ester (L-phe) to the γ-PGA aqueous solution in sequence, stirring the solution until the solution becomes uniformly translucent, and then leaving it at room temperature for 24-48 hours to obtain a mixed solution; (a3) adding anhydrous ethanol to the mixed solution to obtain a precipitate, collecting the precipitate by centrifugation, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 24-72 hours to remove small molecules and obtain an aqueous solution of L-Phe-γ-PGA; (a5) freeze-drying the L-Phe-γ-PGA aqueous solution to obtain an L-Phe-γ-PGA amphiphilic derivative; (b) Preparation of astaxanthin nanoparticles: (b1) dissolving the L-Phe-γ-PGA amphiphilic derivative in deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) adding 10% astaxanthin oil to an aqueous solution of an amphiphilic derivative of L-Phe-γ-PGA, and then treating the solution with an ultrasonic probe in an ice bath for 3-5 minutes, and repeating the process 3-5 times to obtain a uniform colloidal particle dispersion; (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 24-72 hours to remove unloaded small molecular substances to obtain a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

[0004] The invention adopts the hydrophobic small molecule L-phe to modify γ-PGA to obtain the amphiphilic derivative L-phe-γ-PGA, and then uses a simple and feasible macromolecular self-assembly method to load astaxanthin on the amphiphilic derivative L-phe-γ-PGA under the hydrophilic and hydrophobic effects to form an astaxanthin nanoparticle with a hydrophobic core layer and a hydrophilic shell layer, and the carrier material γ-PGA has good biocompatibility and degradability.

[0005] Furthermore, in step (a1), the amount of γ-PGA added is 1-10% by mass of the NaHCO3 aqueous solution.

[0006] Furthermore, in step (a1), the molecular weight range of γ-PGA is (1×10 5 )-(5×10 5 )Da, the concentration of NaHCO3 aqueous solution is 0.1-0.5mol / L.

[0007] Furthermore, in step (a2), the amount of EDC added is 2-20% by mass of the γ-PGA aqueous solution, and the amount of L-phe added is 1.5-15% by mass of the γ-PGA aqueous solution; Furthermore, in step (a2), the stirring temperature is 0-4°C, the stirring time is 0.5-5h, and the stirring speed is 500-1000r / min.

[0008] Furthermore, in step (a3), the volume ratio of the mixed solution to anhydrous ethanol is 1:(3-4).

[0009] Furthermore, in step (a3), the centrifugal speed is 10000-15000 r / min, and the centrifugal time is 5-15 min.

[0010] Furthermore, in step (b1), the mass fraction of the L-Phe-γ-PGA amphiphilic derivative in the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative is 0.5-2%.

[0011] Furthermore, in step (b1), the mass fraction of the L-Phe-γ-PGA amphiphilic derivative in the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative is 1-2%.

[0012] Furthermore, in step (b2), the 10% astaxanthin oil is an oil mixture with an astaxanthin content of 10%.

[0013] Furthermore, in step (b2), the amount of astaxanthin oil added is 20-50% of the mass of the L-Phe-γ-PGA amphiphilic derivative.

[0014] Furthermore, in step (b2), the ultrasonic output power is 90-120 W, the pulse width is 2-5 s, and the intermittent time is 1-3 s.

[0015] Furthermore, in step (b3), the dialysis time is 48 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention selects the hydrophilic biomacromolecule γ-PGA as a carrier and utilizes the principle of macromolecular self-assembly to prepare an astaxanthin nanoparticle, which effectively improves the stability and water solubility of astaxanthin and greatly increases the utilization of astaxanthin.

[0017] (2) The astaxanthin nanoparticles prepared by the present invention have good stability and water solubility, which effectively solves the problems of astaxanthin being easily oxidized, unstable in nature, and poor in water solubility. They also have good permeability and sustained release, greatly improving the market utilization rate of astaxanthin.

[0018] (3) The carrier material selected in the present invention is γ-PGA, which has good biocompatibility and degradability, and is safe and non-toxic. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the effect of temperature on astaxanthin retention; Figure 2 is the effect of natural light on astaxanthin retention; Figure 3 is the effect of oxygen in air on astaxanthin retention; Figure 4 It is an in vitro release experiment of astaxanthin. DETAILED DESCRIPTION

[0020] Example 1 A method for preparing astaxanthin nanoparticles comprises the following steps: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) 1g of a substance with a molecular weight of 5×10 5Da of γ-polyglutamic acid (γ-PGA) was dissolved in 50 mL of 0.1 mol / L NaHCO3 aqueous solution and stirred until fully dissolved to obtain a γ-PGA aqueous solution; (a2) 2.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 1.8 g of a hydrophobic small molecule L-phenylalanine ethyl ester (L-phe) were added to the γ-PGA aqueous solution in sequence, and stirred at 0°C and 700 r / min for 5 h until the solution became uniformly translucent, and then allowed to stand at room temperature for 24 h to obtain a mixed solution; (a3) adding 3 times the volume of anhydrous ethanol to the mixed solution for precipitation, centrifuging at 12000 r / min for 15 min, collecting the precipitate, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 72 h to remove ethanol and obtain an aqueous solution of L-Phe-γ-PGA; (a5) freeze-drying the L-Phe-γ-PGA aqueous solution to obtain an L-Phe-γ-PGA amphiphilic derivative; (b) Preparation of astaxanthin nanoparticles: (b1) dissolving 0.5 g of L-Phe-γ-PGA amphiphilic derivative in 50 mL of deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) 0.15 g of astaxanthin oil (10%) was added to the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative, and then placed in an ice bath and treated with an ultrasonic probe for 3 min. The ultrasonic output power was 90 W, the pulse width was 3 s, and the interval time was 2 s. This was repeated 5 times to obtain a uniform colloidal particle dispersion. (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 48 h to remove unloaded small molecular substances, thereby obtaining a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

[0021] Example 2 A method for preparing astaxanthin nanoparticles comprises the following steps: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) 2 g of a substance with a molecular weight of 3 × 10 5 Da of γ-polyglutamic acid (γ-PGA) was dissolved in 50 mL of 0.3 mol / L NaHCO3 aqueous solution and stirred until fully dissolved to obtain a γ-PGA aqueous solution; (a2) 5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 4 g of a hydrophobic small molecule L-phenylalanine ethyl ester (L-phe) were added to the γ-PGA aqueous solution in sequence, and stirred at 4°C and 800 r / min for 4 h until the solution became uniformly translucent, and then allowed to stand at room temperature for 24 h to obtain a mixed solution; (a3) adding 4 times the volume of anhydrous ethanol to the mixed solution for precipitation, centrifuging at 15000 r / min for 10 min, collecting the precipitate, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 72 h to remove ethanol and obtain an aqueous solution of L-Phe-γ-PGA; (a5) preparing an aqueous solution of L-Phe-γ-PGA to obtain an amphiphilic derivative of L-Phe-γ-PGA; (b) Preparation of astaxanthin nanoparticles: (b1) dissolving 0.75 g of L-Phe-γ-PGA amphiphilic derivative in 50 mL of deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) 0.18 g of astaxanthin oil (10%) was added to the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative, and then placed in an ice bath and treated with an ultrasonic probe for 3 min. The ultrasonic output power was 120 W, the pulse width was 2 s, and the interval time was 1 s. This was repeated 3 times to obtain a uniform colloidal particle dispersion. (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 48 h to remove unloaded small molecular substances, thereby obtaining a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

[0022] Example 3 A method for preparing astaxanthin nanoparticles comprises the following steps: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) 2.5 g of a substance with a molecular weight of 1×10 5 Da of γ-polyglutamic acid (γ-PGA) was dissolved in 50 mL of 0.2 mol / L NaHCO3 aqueous solution and stirred until fully dissolved to obtain a γ-PGA aqueous solution; (a2) 5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 2.5 g of a hydrophobic small molecule L-phenylalanine ethyl ester (L-phe) were added to the γ-PGA aqueous solution in sequence, and stirred at 2°C and 500 r / min for 5 h until the solution became uniformly translucent, and then allowed to stand at room temperature for 48 h to obtain a mixed solution; (a3) adding 3 times the volume of anhydrous ethanol to the mixed solution for precipitation, centrifuging at 15000 r / min for 10 min, collecting the precipitate, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 72 h to remove ethanol and obtain an aqueous solution of L-Phe-γ-PGA; (a5) freeze-drying the L-Phe-γ-PGA aqueous solution to obtain an L-Phe-γ-PGA amphiphilic derivative; (b) Preparation of astaxanthin nanoparticles: (b1) dissolving 1 g of L-Phe-γ-PGA amphiphilic derivative in 50 mL of deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) 0.2 g of astaxanthin oil (10%) was added to the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative, and then placed in an ice bath and treated with an ultrasonic probe for 5 min. The ultrasonic output power was 90 W, the pulse width was 3 s, and the interval time was 2 s. This was repeated 3 times to obtain a uniform colloidal particle dispersion. (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 48 h to remove unloaded small molecular substances, thereby obtaining a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

[0023] Example 4 A method for preparing astaxanthin nanoparticles comprises the following steps: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) 1.5 g of a substance with a molecular weight of 2.5×10 5 Da of γ-polyglutamic acid (γ-PGA) was dissolved in 50 mL of 0.2 mol / L NaHCO3 aqueous solution and stirred until fully dissolved to obtain a γ-PGA aqueous solution; (a2) 3.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 2.7 g of a hydrophobic small molecule L-phenylalanine ethyl ester (L-phe) were added to the γ-PGA aqueous solution in sequence, and the mixture was stirred at 3°C ​​and 1000 r / min for 5 h until the solution became uniformly translucent, and then allowed to stand at room temperature for 48 h to obtain a mixed solution; (a3) adding anhydrous ethanol to the mixed solution for precipitation, centrifuging at 10,000 r / min for 15 min, collecting the precipitate, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 72 h to remove ethanol and obtain an aqueous solution of L-Phe-γ-PGA; (a5) The L-Phe-γ-PGA aqueous solution is freeze-dried to obtain an L-Phe-γ-PGA amphiphilic derivative.

[0024] (b) Preparation of astaxanthin nanoparticles: (b1) dissolving 1 g of L-Phe-γ-PGA amphiphilic derivative in 50 mL of deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) 0.3 g of astaxanthin oil (10%) was added to the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative, and then placed in an ice bath and treated with an ultrasonic probe for 5 min. The ultrasonic output power was 100 W, the pulse width was 5 s, the interval time was 3 s, and repeated 4 times to obtain a uniform colloidal particle dispersion; (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 48 h to remove unloaded small molecular substances, thereby obtaining a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

[0025] Experimental Example 1 Determination of drug loading and loading rate of astaxanthin nanoparticles The drug loading and loading rate of the astaxanthin nanoparticles in Examples 1-4 were tested. The test results are listed in Table 1.

[0026] The astaxanthin content in astaxanthin nanoparticles was measured by ultraviolet spectrophotometry. 15.00 mg of astaxanthin analytical reference was accurately weighed into a 25 mL volumetric flask, dissolved with dimethyl sulfoxide, fixed to scale, and ultrasonically mixed; 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 5.0 mL of astaxanthin-dimethyl sulfoxide solution were respectively drawn into a 10 mL volumetric flask, fixed to scale with dimethyl sulfoxide, and shaken. Using dimethyl sulfoxide as a blank control, the absorbance of the astaxanthin reference was measured at 478 nm, and the regression equation y=0.0458x+0.0125 (y is absorbance, x is astaxanthin mass concentration) was obtained, and R=0.9991. A certain amount of astaxanthin nanoparticles was weighed and dissolved in dimethyl sulfoxide solution, the absorbance was measured at 478 nm, and the astaxanthin content in the nanoparticles was calculated according to the regression equation.

[0027] The calculation formula of astaxanthin nanoparticle drug loading and loading rate is as follows: Where: W1: astaxanthin content in nanoparticles, W2: total mass of nanoparticles; Wherein: W1: the content of astaxanthin in the nanoparticles, W3: the dosage of all astaxanthin.

[0028] Table 1. Drug loading and loading rate of astaxanthin nanoparticles As can be seen from Table 1, the drug loading of the astaxanthin nanoparticles prepared by the present invention is as high as 11.08%, and the average drug loading is 10.43%; the loading rate is as high as 96.31%, and the average loading rate is 95.46%, indicating that the astaxanthin nanoparticles prepared by the method of the present invention have a high utilization rate of astaxanthin.

[0029] Experimental Example 2 Determination of water solubility of astaxanthin nanoparticles The solubility of the astaxanthin nanoparticles and astaxanthin oil of Examples 1-4 was tested. The test results are listed in Table 2.

[0030] 200 mg of astaxanthin nanoparticles and astaxanthin oil (10% astaxanthin content) were weighed and added to 4 mL of water, and dissolved under ultrasound at 20°C in the dark for 1 hour to form a supersaturated solution of the two. The solution was filtered with a 0.45 µm disposable syringe filter, and the filtrate was appropriately diluted and analyzed according to the astaxanthin content detection method in Example 1, and the change in the solubility of astaxanthin in water before and after loading was calculated.

[0031] Table 2. Solubility of astaxanthin nanoparticles It can be seen from Table 2 that the solubility of astaxanthin oil is 0, and the solubility of the astaxanthin nanoparticles of Examples 1-4 is as low as 96.57%, indicating that the astaxanthin nanoparticles prepared by the present invention have good water solubility, which effectively solves the problem of poor water solubility of astaxanthin.

[0032] Experimental Example 3 Determination of the stability of astaxanthin nanoparticles Effect of temperature on astaxanthin nanoparticles: Take appropriate amounts of astaxanthin nanoparticles prepared by the present invention and astaxanthin oil (astaxanthin content is 10%), place them at 4°C, 20°C, 40°C, 60°C and 80°C respectively, take samples after 24 hours to measure astaxanthin retention rate, and investigate the effect of temperature on stability. The test results are shown in the attached Figure 1 .

[0033] Effect of natural light on astaxanthin nanoparticles: Take appropriate amount of astaxanthin nanoparticles prepared by the present invention and astaxanthin oil (astaxanthin content is 10%), seal at room temperature 25°C, store under natural light for 30 days, take samples regularly to measure astaxanthin retention rate, and investigate the effect of natural light on stability. The test results are shown in the attached Figure 2 .

[0034] Effect of oxygen in the air on astaxanthin nanoparticles: Take appropriate amounts of astaxanthin nanoparticles prepared by the present invention and astaxanthin oil (astaxanthin content is 10%), place them in a watch dish, store them at room temperature at 25°C in the dark for 30 days, take samples regularly to determine the astaxanthin retention rate, and investigate the effect of oxygen in the air on stability. The test results are shown in the attached Figure 3 .

[0035] The astaxanthin retention rate was calculated according to the following formula: The results are attached Figure 1-3 As shown, the astaxanthin nanoparticles prepared by the present invention can significantly improve the sensitivity of astaxanthin to light, heat and oxygen, and improve the stability of astaxanthin.

[0036] Experimental Example 4 Determination of in vitro release of astaxanthin nanoparticles Weigh 100 mg of astaxanthin-loaded nanoparticles and add them to a dialysis bag. Add 3 mL of PBS solution (pH 7.4) containing 10% acetone to disperse the nanoparticles. Clamp the two ends of the dialysis bag with clamps and immerse it in 150 mL of PBS solution (pH 7.4) containing 10% acetone. Gently shake it at 37°C and 50 rpm. Take 5 mL of samples at 0, 1, 2, 4, 6, 8, 12, 18 and 24 h, and replenish it with 5 mL of fresh dissolution medium. Continue sampling for 24 h. Repeat the experiment 3 times. Take the average value of the results to calculate the cumulative release rate of the nanoparticles. Use an ultraviolet spectrophotometer to measure the absorbance value of the supernatant, and calculate the concentration of astaxanthin to obtain the release rate of astaxanthin. Weigh 100 mg of astaxanthin oil (astaxanthin content is 10%) as a control, and determine the in vitro release rate of astaxanthin oil using the above method. See the attached test results. Figure 4 .

[0037] The cumulative release percentage formula is: Wherein: Ci: the concentration of astaxanthin in the release medium at time point i; Ct: the concentration of astaxanthin in the release medium at time point n; Vi: sampling volume; V: the total volume of the release medium.

[0038] The results are as follows Figure 4 As shown, the astaxanthin nanoparticles prepared by the present invention have good sustained release properties compared with astaxanthin oil.

Claims

1. A method for preparing astaxanthin nanoparticles, characterized in that: The steps include: (a) Preparation of amphiphilic γ-polyglutamic acid derivatives: (a1) dissolving γ-polyglutamic acid (γ-PGA) in a NaHCO3 aqueous solution and stirring until fully dissolved to obtain a γ-PGA aqueous solution; (a2) adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and L-phenylalanine ethyl ester (L-phe) to the γ-PGA aqueous solution in sequence, stirring the solution until the solution becomes uniformly translucent, and then leaving it at room temperature for 24-48 hours to obtain a mixed solution; (a3) adding anhydrous ethanol to the mixed solution to obtain a precipitate, collecting the precipitate by centrifugation, and re-dissolving it with an equal volume of deionized water to obtain a re-dissolved solution; (a4) dialyzing the reconstituted solution in a dialysis bag with a molecular weight of 3500 Da for 24-72 hours to remove small molecules and obtain an L-Phe-γ-PGA aqueous solution; (a5) freeze-drying the L-Phe-γ-PGA aqueous solution to obtain an L-Phe-γ-PGA amphiphilic derivative; (b) Preparation of astaxanthin nanoparticles: (b1) dissolving the L-Phe-γ-PGA amphiphilic derivative in deionized water and stirring until fully dissolved to obtain an aqueous solution of the L-Phe-γ-PGA amphiphilic derivative; (b2) adding 10% astaxanthin oil to an aqueous solution of an amphiphilic derivative of L-Phe-γ-PGA, and then treating the solution with an ultrasonic probe in an ice bath for 3-5 minutes, and repeating the process 3-5 times to obtain a uniform colloidal particle dispersion; (b3) dialyzing the uniform colloidal particle dispersion in a dialysis bag with a molecular weight of 3500 Da for 24-72 hours to remove unloaded small molecular substances to obtain a colloidal particle dispersion; (b4) freeze-drying the colloidal particle dispersion to obtain astaxanthin nanoparticles.

2. The method for preparing astaxanthin nanoparticles according to claim 1, characterized in that: In step (a1), the amount of γ-PGA added is 1-10% of the mass of the NaHCO3 aqueous solution; the molecular weight range of γ-PGA is (1×10 5 )-(5×10 5 )Da, the concentration of NaHCO3 aqueous solution is 0.1-0.5mol / L.

3. The method for preparing astaxanthin nanoparticles according to claim 1, characterized in that: In step (a2), the amount of EDC added is 2-20% by mass of the γ-PGA aqueous solution, and the amount of L-phe added is 1.5-15% by mass of the γ-PGA aqueous solution.

4. The method for preparing astaxanthin nanoparticles according to any one of claims 1 to 3, characterized in that: In step (a2), the stirring temperature is 0-4°C, the stirring time is 0.5-5h, and the stirring speed is 500-1000r / min.

5. The method for preparing astaxanthin nanoparticles according to claim 4, characterized in that: In step (a3), the volume ratio of the mixed solution to anhydrous ethanol is 1:(3-4).

6. The method for preparing astaxanthin nanoparticles according to claim 1, characterized in that: In step (a3), the centrifugal speed is 10000-15000 r / min, and the centrifugal time is 5-15 min.

7. The method for preparing astaxanthin nanoparticles according to claim 1, characterized in that: In step (b1), the mass fraction of the L-Phe-γ-PGA amphiphilic derivative in the aqueous solution of the L-Phe-γ-PGA amphiphilic derivative is 0.5-2%.

8. The method for preparing astaxanthin nanoparticles according to claim 6 or 7, characterized in that: In step (b2), the amount of astaxanthin oil added is 20-50% of the mass of the L-Phe-γ-PGA amphiphilic derivative.

9. The method for preparing astaxanthin nanoparticles according to claim 8, characterized in that: In step (b2), the ultrasonic output power is 90-120 W, the pulse width is 2-5 s, and the intermittent time is 1-3 s.

10. The method for preparing astaxanthin nanoparticles according to claim 1, characterized in that: In step (b3), the dialysis time is 48 hours.

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