CN117186058A - Lipoic acid nanoparticle and preparation method thereof - Google Patents

Abstract

The application relates to the technical field of lipoic acid, in particular to lipoic acid nano particles and a preparation method thereof, and the preparation method of the lipoic acid nano particles comprises the following steps: adding lipoic acid powder into an organic solvent, and stirring and dissolving to form lipoic acid solution; adding the nano particles into a solvent to enable the nano particles to be dispersed in the solvent, so as to obtain a nano carrier solution; dripping lipoic acid solution into nano carrier solution and stirring and mixing to form lipoic acid nano particles; the lipoic acid nano particles are subjected to curing treatment by adopting a heat treatment or chemical crosslinking method; and (3) centrifuging or filtering the solidified lipoic acid nano particles and washing to obtain the lipoic acid nano particles. According to the application, nanoparticles are used as the carrier of the lipoic acid, and the lipoic acid is adsorbed on the surfaces of the nanoparticles, so that lipoic acid molecules are protected by the nanoparticles, the influence of illumination and temperature on the lipoic acid molecules is effectively reduced, and the stability of the lipoic acid is improved.

Description

Lipoic acid nanoparticles and preparation method thereof

Technical field

The present application relates to the technical field of lipoic acid, and in particular to a lipoic acid nanoparticle and a preparation method thereof.

Background technique

Lipoic acid is a natural reducing agent. After being absorbed by the human body, it can be quickly converted into dihydrolipoic acid within the cells and excreted out of the cells. The combined action of lipoic acid and dihydrolipoic acid scavenges nearly all oxidative free radicals in the body. Lipoic acid has been widely researched and used in medicine, food, cosmetics and other fields due to its strong antioxidant capacity.

Because lipoic acid has strong antioxidant properties, lipoic acid exposed to the air is easily oxidized by light and temperature, forming oxidative free radicals of lipoic acid, which can actually reach the human body. The effective content is greatly reduced, and the oxidized lipoic acid emits a pungent smell.

Therefore, improving the stability of lipoic acid is of great significance for its application and development.

Contents of the invention

In order to improve the stability of lipoic acid, this application provides lipoic acid nanoparticles and a preparation method thereof.

In the first aspect, this application provides a method for preparing lipoic acid nanoparticles, adopting the following technical solution:

A preparation method of lipoic acid nanoparticles, including the following steps:

Prepare lipoic acid solution: Add lipoic acid powder to an organic solvent, stir and dissolve to form a 70-80g/L lipoic acid solution;

Preparing the nanocarrier solution: Add the nanoparticles to the solvent to disperse the nanoparticles in the solvent to obtain a nanocarrier solution of 6-10 mg/ml;

Preparing lipoic acid nanoparticles: Drop lipoic acid solution into the nanocarrier solution and stir and mix to form lipoic acid nanoparticles;

Curing lipoic acid nanoparticles: The lipoic acid nanoparticles are cured by heat treatment or chemical cross-linking;

Purification of lipoic acid nanoparticles: Separate the solidified lipoic acid nanoparticles by centrifugation or filtration to obtain lipoic acid nanoparticles and solvent, and then wash the separated lipoic acid nanoparticles to remove residual organic solvents and impurities.

By adopting the above technical solution, nanoparticles are used as the carrier of lipoic acid, and lipoic acid is adsorbed on the surface of the nanoparticles, so that the lipoic acid molecules are protected by the nanoparticles, effectively reducing the effects of light and temperature on them, and improving the efficiency of lipoic acid. The stability enables it to maintain activity and purity under large changes in the external environment; the preparation method of the present application is simple and efficient, suitable for industrial production, can be prepared on a large scale, and can be used to prepare stable lipoic acid pharmaceutical preparations, suitable for Pharmaceutical manufacturing, health care products and cosmetics and other fields.

In a specific embodiment, in the step of preparing lipoic acid solution, the organic solvent is a mixture of ethanol and dimethyl sulfoxide with a mass ratio of (5-15):1.

By adopting the above technical solution, due to the dimerization effect of ethanol and dimethyl sulfoxide on lipoic acid, a certain proportion of ethanol and dimethyl sulfoxide can reduce the polymerization between lipoic acid molecules and increase the concentration of lipoic acid molecules in nanometers. The coating rate of the particle surface improves the stability of lipoic acid.

In a specific embodiment, in the step of preparing the nanocarrier solution, the nanoparticles are one of nanosilica, nanotitanium oxide, nanostarch, and nanosalts.

By adopting the above technical solution, the hydroxyl groups on the surface of nanosilica can form hydrogen bonds with molecules and have strong adsorption properties, which can adsorb lipoic acid molecules to its surface and improve the stability of lipoic acid.

The surface of nano-titanium oxide has active sites and many holes. These active sites and holes have strong adsorption properties for lipoic acid molecules. Lipoic acid molecules will be adsorbed on the surface of nano-titanium oxide to form stable lipoic acid nanoparticles.

Nanostarch is a drug carrier with low raw material price, good biocompatibility and biodegradability. Due to the small particle size of nanostarch and its huge free surface, nanostarch has high colloidal stability and excellent adsorption. performance, and therefore has strong adsorption to lipoic acid molecules.

During the gasification process, nano-salts will form a strongly adherent solid magnetic film layer, which is covered with hundreds of millions of nano-scale tiny needles, which can actively adsorb lipoic acid nanoparticles and has strong adsorption properties. .

In a specific embodiment, the particle size of the nanoparticles is 10-20 nm, the specific surface area is 200-300 m ² /g, and the nano-salt is nano-alumina.

By adopting the above technical solution, as the particle size continues to decrease, the specific surface area of the nanoparticles increases sharply. The high specific surface area increases the number of atoms on the surface of the particles, resulting in a rapid increase in surface energy and surface binding energy. Due to the increased number of original systems on the particle surface, insufficient atomic coordination and high surface energy, the atoms on the particle surface have high chemical activity, are extremely unstable, and can easily combine with other atoms. Therefore, the appropriate particle size and specific surface area of the nanoparticles should be selected so that lipoic acid molecules can be easily adsorbed on their surface to improve the stability of lipoic acid.

There are many active sites on the surface of nano-alumina, which can react chemically with lipoic acid; at the same time, its surface has a micro-nano structure, forming many channels and micropores. The sizes of these channels and micropores are different, which can further increase the strength of alumina. The surface area further improves its adsorption, adsorbs lipoic acid molecules on its surface, and improves the stability of lipoic acid.

In a specific embodiment, in the step of preparing lipoic acid nanoparticles, the volume ratio of the lipoic acid solution to the nanocarrier solution is (70-80): (6-10).

By adopting the above technical solution and optimizing the mass ratio of lipoic acid solution and nanocarrier solution, the coating rate of lipoic acid molecules on the surface of nanoparticles can be increased, thereby improving the stability of lipoic acid.

In a specific embodiment, in the step of preparing lipoic acid nanoparticles, the lipoic acid solution is dropped into the nanocarrier solution at a speed of 2-5 ml/min and stirred for 18-24 hours.

By adopting the above technical solution, the combination of dropping speed and stirring time can affect the contact time and frequency between lipoic acid and nanoparticles. Proper conditions help lipoic acid molecules interact with the nanoparticle surface in the right amount of time, resulting in better coating.

Appropriate stirring time can evenly disperse lipoic acid molecules in the nanoparticle suspension, thereby improving the uniformity of coating; stirring too fast or too slow may cause lipoic acid to be unevenly dispersed in the solution.

At the same time, appropriate stirring time can affect the adsorption and repulsion behavior of lipoic acid molecules on the surface of nanoparticles; appropriate stirring time can help prevent excessive aggregation of lipoic acid molecules on the surface of nanoparticles, thereby achieving better coating effects.

In a specific embodiment, in the preparation step of solidified lipoic acid nanoparticles, the temperature during the heat treatment is 60-100°C and the time is 10-30 minutes.

By adopting the above technical solution, during the curing process, appropriate temperature can affect the reaction rate; higher temperatures usually promote the reaction rate and help form a more stable coating structure in a relatively short time. Temperature can affect the conformation of coating molecules, thereby affecting its adsorption and coating rate on the surface of the nanocarrier; at different temperatures, the coating may have different conformations, which may affect its distribution and interaction on the surface of the carrier . Appropriate curing temperature can promote cross-linking, bonding or other interactions between the coating and the nanocarrier. These chemical reactions help to improve the stability of the coating on the carrier surface.

The curing time determines the degree of interaction between the coating and the nanocarrier; an appropriate curing time ensures that sufficient reaction occurs to form a stable coating. Appropriate curing time can allow cross-linking between coating molecules or to the surface of the carrier, thereby forming a tighter structure and improving the stability of the coating. Different curing times can achieve different degrees of curing. A shorter curing time may cause incompletely reacted coating molecules to still exist, while a longer curing time may result in over-curing, affecting the dispersion and stability of the coating.

In a specific embodiment, in the preparation step of solidified lipoic acid nanoparticles, the chemical cross-linking method refers to modifying lipoic acid nanoparticles with a chemical cross-linking agent, and the chemical cross-linking agent includes One of glutaraldehyde, carboxylic acid cross-linking agent, and carbonic dianhydride.

By adopting the above technical solution and using a chemical cross-linking method to connect lipoic acid nanoparticles through chemical bonds to form a cross-linked network, it is possible to prevent the lipoic acid molecules adsorbed on the surface of the nanoparticles from falling off and improve the adhesion of lipoic acid on the surface of the nanoparticles. adsorption effect.

In a specific embodiment, in the purification and preparation step of lipoic acid nanoparticles: the solidified lipoic acid nanoparticles are centrifuged from the solvent at a rotation speed of 10,000-15,000 rpm, and then separated to obtain The lipoic acid nanoparticles were washed 1-3 times with acetone and then 3 times with deionized water to remove residual organic solvents and impurities.

By adopting the above technical solution, the high-speed centrifugal separation method not only has fast separation speed and high separation efficiency, but also removes the solvent more thoroughly, which can improve the purity of lipoic acid nanoparticles and improve the coating rate of lipoic acid on the nanoparticles.

In the second aspect, this application provides lipoic acid nanoparticles, adopting the following technical solution:

A lipoic acid nanoparticle is prepared using the above preparation method.

To sum up, this application includes at least one of the following beneficial technical effects:

1. This application uses nanoparticles as the carrier of lipoic acid, and adsorbs lipoic acid on the surface of the nanoparticles, so that the lipoic acid molecules are protected by the nanoparticles, effectively reducing the effects of light and temperature on lipoic acid, and improving the stability of lipoic acid. sex;

2. In this application, the speed and stirring time of lipoic acid solution dripping into the nanocarrier solution are optimized, which will help the lipoic acid molecules interact with the surface of the nanoparticles within a suitable time, thereby achieving better coating;

3. During the curing process of this application, the temperature and time of the heat treatment are optimized. Appropriate temperature can affect the reaction rate; higher temperature usually promotes the reaction rate and helps to form a more stable coating in a relatively short time. structure, improve the coating rate, thereby further improving the stability of lipoic acid.

Detailed ways

The following examples further illustrate this application in detail.

Example

Example 1

This embodiment discloses a method for preparing lipoic acid nanoparticles, which specifically includes the following steps:

S1, add 70g lipoic acid powder to 1L organic solution formed by mixing 833ml ethanol and 167ml dimethyl sulfoxide, stir to completely dissolve lipoic acid in the organic solvent, and obtain a 70g/L lipoic acid solution;

S2, add 6㎎ of nano-silica with a particle size of 10 nm and a specific surface area of 300 m ² /g into 1 ml of deionized water, and stir to disperse the nano-silica in the deionized water to obtain a 6㎎/ml nano-carrier solution;

S3, add 70 ml of the above-mentioned lipoic acid solution dropwise into the above-mentioned 6 ml nanocarrier solution at a speed of 2 ml/min, and stir for 24 hours to form lipoic acid nanoparticles;

S4, heat-treat the above-mentioned lipoic acid nanoparticles at a temperature of 60°C for 30 minutes to solidify lipoic acid molecules on the surface of the nanoparticles to form solidified lipoic acid nanoparticles;

S5, separate the solidified lipoic acid nanoparticles from the solvent at a rotation speed of 10,000 rpm; then wash the separated lipoic acid nanoparticles once with acetone and then wash them three times with deionized water. .

Example 2

The difference between this example and Example 1 is that in S1, 70g lipoic acid powder is added to 1L organic solution formed by mixing 818ml ethanol and 182ml dimethyl sulfoxide, and stirred to completely dissolve lipoic acid in the organic solvent to obtain 70g/ L lipoic acid solution.

Example 3

The difference between this example and Example 1 is that, in S1, 70g lipoic acid powder is added to 1L organic solution formed by mixing 937.5ml ethanol and 62.5ml dimethyl sulfoxide, and stirred to completely dissolve lipoic acid in the organic solvent. Obtain 70g/L lipoic acid solution.

Example 4

The difference between this example and Example 2 is that in S1, 75g lipoic acid powder is added to 1L organic solution formed by mixing 818ml ethanol and 182ml dimethyl sulfoxide, and stirred to completely dissolve lipoic acid in the organic solvent to obtain 75g /L lipoic acid solution.

Example 5

The difference between this example and Example 2 is that in S1, 80g lipoic acid powder is added to 1L organic solution formed by mixing 818ml ethanol and 182ml dimethyl sulfoxide, and stirred to completely dissolve lipoic acid in the organic solvent to obtain 80g /L lipoic acid solution.

Example 6

The difference between this example and Example 4 is that in S2, 8 mg of nano-silica with a particle size of 10 nm and a specific surface area of 300 m ² /g is added to 1 ml of deionized water, and stirred to disperse the nano-silica in the deionized water. , to obtain 8㎎/ml nanocarrier solution.

Example 7

The difference between this example and Example 4 is that in S2, 10 mg of nano-silica with a particle size of 10 nm and a specific surface area of 300 m ² /g is added to 1 ml of deionized water, and stirred to disperse the nano-silica in the deionized water. , to obtain a 10㎎/ml nanocarrier solution.

Example 8

The difference between this example and Example 6 is that, in S2, 8 mg of nano-silica with a particle size of 10 nm and a specific surface area of 300 m ² /g is added to 1 ml of deionized water, and the nano-silica is dispersed in deionized water through ultrasonic treatment. In water, an 8㎎/ml nanocarrier solution was obtained.

Example 9

The difference between this example and Example 6 is that in S2, 8 mg of nano-titanium oxide with a particle size of 10 nm and a specific surface area of 300 m ² /g is added to 1 ml of deionized water, and stirred to disperse the nano-titanium oxide in the deionized water to obtain 8㎎/ml nanocarrier solution.

Example 10

The difference between this example and Example 6 is that, in S2, 8 mg of nano-alumina with a particle size of 10 nm and a specific surface area of 300 m ² /g is added to 1 ml of deionized water, and stirred to disperse the nano-alumina in the deionized water to obtain 8㎎/ml nanocarrier solution.

Example 11

The difference between this example and Example 6 is that in S2, 8㎎ of nanostarch with a particle size of 10nm and a specific surface area of 300m ² /g is added to 1 ml of deionized water, and stirred to disperse the nanostarch in the deionized water to obtain 8㎎ /ml nanocarrier solution.

Example 12

The difference between this example and Example 6 is that in S2, 8 mg of nano-silica with a particle size of 20 nm and a specific surface area of 200 m ² /g is added to 1 ml of deionized water, and stirred to disperse the nano-silica in the deionized water. , to obtain 8㎎/ml nanocarrier solution.

Example 13

The difference between this embodiment and Example 6 is that in S3, 75 ml of the above-mentioned lipoic acid solution was dropped into the above-mentioned 8 ml nanocarrier solution at a speed of 2 ml/min, and stirred for 24 hours to form lipoic acid nanoparticles.

Example 14

The difference between this embodiment and Example 6 is that in S3, 80 ml of the above-mentioned lipoic acid solution was dropped into the above-mentioned 10 ml nanocarrier solution at a speed of 2 ml/min, and stirred for 24 hours to form lipoic acid nanoparticles.

Example 15

The difference between this embodiment and Example 13 is that in S3, 75 ml of the above-mentioned lipoic acid solution was dropped into the above-mentioned 8 ml nanocarrier solution at a speed of 5 ml/min, and stirred for 18 hours to form lipoic acid nanoparticles.

Example 16

The difference between this embodiment and Example 13 is that in S4, the above-mentioned lipoic acid nanoparticles are heat-treated at a temperature of 100°C for 10 minutes to solidify lipoic acid molecules on the surface of the nanoparticles to form solidified lipoic acid nanoparticles.

Example 17

The difference between this embodiment and Example 13 is that in S4, 10 g of glutaraldehyde is added to the above 100 g of lipoic acid nanoparticles for modification treatment to obtain solidified lipoic acid nanoparticles.

Example 18

The difference between this embodiment and Example 17 is that in S4, 10g N-hydroxysuccinimide (carboxylic acid cross-linking agent) is added to the above 100g lipoic acid nanoparticles for modification treatment to obtain solidified lipoic acid nanoparticles. .

Example 19

The difference between this embodiment and Example 17 is that in S4, 10g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (carbonic dianhydride) was added to the above 100g of lipoic acid nanoparticles. Modification treatment is performed to obtain solidified lipoic acid nanoparticles.

Example 20

The difference between this embodiment and Example 17 is that in S5, the solidified lipoic acid nanoparticles are separated from the solvent at a rotation speed of 15,000 rpm; and then the separated lipoic acid nanoparticles are washed three times with acetone. Then wash it 3 times with deionized water.

Example 21

The difference between this embodiment and Example 17 is that in S5, the solidified lipoic acid nanoparticles are filtered and dried at 120°C to separate the lipoic acid nanoparticles from the solvent; and then the separated lipoic acid nanoparticles are washed with acetone. After 3 times, wash it again with deionized water 3 times.

Comparative ratio

Comparative example 1

The difference between this comparative example and Example 1 is that lipoic acid CAS: 62-46-4.

Comparative example 2

The difference between this comparative example and Example 13 is that in S3, 70 ml of the above-mentioned lipoic acid solution was dropped into the above-mentioned 6 ml nanocarrier solution at a speed of 1 ml/min, and stirred for 30 hours to form lipoic acid nanoparticles.

Comparative example 3

The difference between this comparative example and Comparative Example 13 is that in S3, 70 ml of the above-mentioned lipoic acid solution was dropped into the above-mentioned 6 ml nanocarrier solution at a speed of 6 ml/min, and stirred for 17 hours to form lipoic acid nanoparticles.

Comparative example 4

The difference between this comparative example and Comparative Example 13 is that in S4, the above-mentioned lipoic acid nanoparticles are heat-treated at a temperature of 50°C for 40 minutes to solidify lipoic acid molecules on the surface of the nanoparticles to form solidified lipoic acid nanoparticles.

Comparative example 5

The difference between this comparative example and Comparative Example 13 is that in S4, the above-mentioned lipoic acid nanoparticles are heat-treated at a temperature of 110°C for 5 minutes to solidify lipoic acid molecules on the surface of the nanoparticles to form solidified lipoic acid nanoparticles.

Performance testing

1. Stability

Stability testing was conducted in accordance with the 2022 Edition of the Chinese Pharmacopoeia, Part 4 - Stability Test + Methodological Verification Guiding Principles.

The lipoic acid particles prepared in Examples 1-21 and Comparative Examples 1-5 are placed in a suitable open container and spread into a thick thin layer. The loose raw materials are spread into a 10mm thick thin layer. The following tests are carried out, specifically: Place the open container in a light box equipped with a fluorescent lamp (40-50°C) and place it for 10 days at an illumination of 4500±500lx. Take a sample on the 10th day to observe whether lipoic acid emits a pungent smell and record the results. in Table 1.

2. Covering rate

Calculate the coating rate of lipoic acid nanoparticles prepared in Examples 1-21 and Comparative Examples 2-5. Covering rate = (mass of lipoic acid nanoparticles - mass of used nanoparticles)/used lipoic acid powder × 100% , the results are recorded in Table 1.

Table 1 Performance testing data table of Examples 1-21 and Comparative Examples 1-5

Referring to Table 1, combined with Example 1 and Comparative Example 1, it can be seen that the lipoic acid nanoparticles prepared by the preparation method of the present application have better stability than ordinary lipoic acid. The preparation method of this application uses nanoparticles as the carrier of lipoic acid, and adsorbs lipoic acid on the surface of the nanoparticles, so that the lipoic acid molecules are protected by the nanoparticles, effectively reducing the impact of light on them, and improving the stability of lipoic acid.

Referring to Table 1, combined with Examples 13, 15 and Comparative Examples 2-3, it can be seen that when preparing lipoic acid nanoparticles, optimizing the speed and stirring time of lipoic acid solution dripping into the nanocarrier solution can improve lipoic acid nanoparticles. The coating rate and the stability of the prepared lipoic acid nanoparticles; the combination of dropping speed and stirring time can affect the contact time and frequency between lipoic acid and nanoparticles. Appropriate conditions help lipoic acid molecules interact with the nanoparticle surface within the right time, thereby achieving a high coating rate. Proper stirring can evenly disperse lipoic acid molecules in the nanoparticle suspension, thereby improving the uniformity of coating; stirring too fast or too slow may cause lipoic acid to be unevenly dispersed in the solution. At the same time, stirring can affect the adsorption and repulsion behavior of lipoic acid molecules on the surface of nanoparticles; appropriate stirring can help prevent excessive aggregation of lipoic acid molecules on the surface of nanoparticles, thereby achieving a better coating effect, thereby improving the performance of lipoic acid nanoparticles. stability.

Referring to Table 2, combined with Examples 13, 16 and Comparative Examples 4-5, it can be seen that by optimizing the temperature and time during heat treatment, the coating and stability of lipoic acid nanoparticles can be improved. During the curing process, appropriate temperature can affect the reaction rate; higher temperatures generally promote the reaction rate and help form a more stable coating structure in a relatively short time. Temperature can affect the conformation of coating molecules, thereby affecting its adsorption and coating rate on the surface of the nanocarrier; at different temperatures, the coating may have different conformations, which may affect its distribution and interaction on the surface of the carrier . Appropriate curing temperature can promote cross-linking, bonding or other interactions between the coating and the nanocarrier. These chemical reactions help to improve the stability of the coating on the carrier surface.

The curing time determines the degree of interaction between the coating and the nanocarrier; an appropriate curing time ensures that sufficient reaction occurs to form a stable coating. Appropriate curing time can allow cross-linking between coating molecules or to the surface of the carrier, thereby forming a tighter structure and improving the stability of the coating. Different curing times can achieve different degrees of curing. A shorter curing time may cause incompletely reacted coating molecules to still exist, while a longer curing time may result in over-curing, affecting the dispersion and stability of the coating.

This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contribution as needed, but as long as the rights of this application are All requirements are protected by patent law.

Claims (10)

1. A method for preparing lipoic acid nano particles, which is characterized by comprising the following steps: the method comprises the following steps:

preparation of lipoic acid solution: adding lipoic acid powder into an organic solvent, stirring and dissolving to form 70-80g/L lipoic acid solution;

preparing a nano carrier solution: adding the nano particles into a solvent to enable the nano particles to be dispersed in the solvent, so as to obtain a nano carrier solution with the concentration of 6-10 mg/ml;

preparation of lipoic acid nanoparticles: dripping lipoic acid solution into nano carrier solution and stirring and mixing to form lipoic acid nano particles;

curing lipoic acid nanoparticles: curing the lipoic acid nano particles by adopting a heat treatment or chemical crosslinking method;

purification of lipoic acid nano particles: and separating the solidified lipoic acid nano particles by a centrifugal or filtering method to obtain lipoic acid nano particles and a solvent, and washing the separated lipoic acid nano particles to remove residual organic solvent and impurities.

2. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: in the preparation step of the lipoic acid solution, the organic solvent is prepared from the following components in percentage by mass (5-15): 1 and dimethyl sulfoxide.

3. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: in the preparation step of the nano-carrier solution, the nano-particles are one of nano-silicon dioxide, nano-titanium oxide, nano-starch and nano-salts.

4. A method for preparing lipoic acid nanoparticles according to claim 3, characterized in that: the particle diameter of the nano particles is 10-20nm, and the specific surface area is 200-300m ² /g。

5. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: in the preparation step of the lipoic acid nanoparticle, the volume ratio of the lipoic acid solution to the nano-carrier solution is (70-80): (6-10).

6. The method for preparing lipoic acid nanoparticles according to claim 5, wherein the steps of: in the preparation step of the lipoic acid nanoparticle, the lipoic acid solution is dripped into the nano-carrier solution at the speed of 2-5ml/min and stirred for 18-24h.

7. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: in the preparation step of the solidified lipoic acid nano particles, the temperature during the heat treatment is 60-100 ℃ and the time is 10-30min.

8. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: in the preparation step of the solidified lipoic acid nano particles, the chemical crosslinking method is to modify the lipoic acid nano particles by using a chemical crosslinking agent, wherein the chemical crosslinking agent comprises one of glutaraldehyde, a carboxylic acid crosslinking agent and carbonic acid dianhydride.

9. The method for preparing lipoic acid nanoparticles according to claim 1, wherein the method comprises the steps of: the lipoic acid nanoparticle purification preparation steps are as follows: centrifuging the solidified lipoic acid nano particles at the rotating speed of 10000-15000rpm to obtain lipoic acid nano particles and solvent, washing the separated lipoic acid nano particles with acetone for 1-3 times, and washing with deionized water for 3 times to remove residual organic solvent and impurities.

10. A lipoic acid nanoparticle characterized by: the lipoic acid nanoparticle according to any one of claims 1 to 9.