Lipoic acid nanoparticles and methods of making the same
By preparing lipoic acid nanoparticles with nanoparticle carriers, the problem of lipoic acid's easy oxidation in air was solved, and its stability and activity were maintained under changes in the external environment, making it suitable for pharmaceuticals and cosmetics.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU TOHOPE PHARMA
- Filing Date
- 2023-08-21
- Publication Date
- 2026-05-15
AI Technical Summary
Lipoic acid is easily oxidized by light and temperature when exposed to air, resulting in a reduction in its effective content and the production of a pungent odor, which affects its application stability.
Using nanoparticles as a carrier for lipoic acid, stable lipoic acid nanoparticles are formed by preparing lipoic acid nanoparticles and subjecting them to heat treatment or chemical cross-linking, combined with appropriate stirring, dropping speed and solution ratio.
It improves the stability of lipoic acid, reduces the effects of light and temperature, maintains its activity and purity, and is suitable for pharmaceutical formulations and cosmetics.
Smart Images
Figure BDA0004404888340000081 
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Abstract
Description
Technical Field
[0001] This application relates to the field of thioctic acid technology, and in particular to a thioctic acid nanoparticle and a method for preparing the same. Background Technology
[0002] Lipoic acid is a natural reducing agent. After being absorbed by the human body, it can be rapidly converted into dihydrolipoic acid within cells and then excreted from the cells. The combined action of lipoic acid and dihydrolipoic acid can eliminate almost all oxidative free radicals in the body. Due to its strong antioxidant capacity, lipoic acid has been widely studied and applied in the fields of medicine, food, and cosmetics.
[0003] Because lipoic acid has strong antioxidant properties, it is easily oxidized by light and temperature when exposed to air, forming lipoic acid free radicals. This results in a significant reduction in the effective amount of lipoic acid that can actually reach the human body. At the same time, oxidized lipoic acid emits a pungent odor.
[0004] Therefore, improving the stability of thioctic acid is of great significance for its application and development. Summary of the Invention
[0005] To improve the stability of lipoic acid, this application provides lipoic acid nanoparticles and a method for preparing the same.
[0006] In a first aspect, this application provides a method for preparing lipoic acid nanoparticles, employing the following technical solution:
[0007] A method for preparing lipoic acid nanoparticles includes the following steps:
[0008] Preparation of lipoic acid solution: Add lipoic acid powder to an organic solvent and stir to dissolve to form a 70-80 g / L lipoic acid solution;
[0009] Preparation of nanocarrier solution: Nanoparticles are added to a solvent to disperse the nanoparticles in the solvent, resulting in a nanocarrier solution with a concentration of 6-10 mg / ml.
[0010] Preparation of lipoic acid nanoparticles: Lipoic acid solution is added dropwise to nanocarrier solution and stirred to form lipoic acid nanoparticles;
[0011] Curing lipoic acid nanoparticles: Lipoic acid nanoparticles are cured by heat treatment or chemical cross-linking.
[0012] Purification of lipoic acid nanoparticles: The solidified lipoic acid nanoparticles are separated into lipoic acid nanoparticles and solvent by centrifugation or filtration. The separated lipoic acid nanoparticles are then washed to remove residual organic solvents and impurities.
[0013] By employing the above technical solution, nanoparticles are used as carriers for lipoic acid, which is adsorbed onto the surface of the nanoparticles. This protects the lipoic acid molecules, effectively reducing the influence of light and temperature, and improving the stability of lipoic acid. This allows it to maintain its activity and purity even under significant changes in the external environment. The preparation method of this application is simple and efficient, suitable for industrial production, and can be prepared on a large scale. It can be used to prepare stable lipoic acid drug formulations and is applicable to fields such as pharmaceutical manufacturing, health products, and cosmetics.
[0014] In one specific implementation, in the step of preparing the thioctic acid solution, the organic solvent is a mixture of ethanol and dimethyl sulfoxide in a mass ratio of (5-15):1.
[0015] By adopting the above technical solution, since ethanol and dimethyl sulfoxide have a dimerizing effect on lipoic acid, a certain proportion of ethanol and dimethyl sulfoxide can reduce the polymerization between lipoic acid molecules, increase the coating rate of lipoic acid molecules on the surface of nanoparticles, and thus improve the stability of lipoic acid.
[0016] In one specific implementation, in the step of preparing the nanocarrier solution, the nanoparticles are one of nano-silica, nano-titanium oxide, nano-starch, and nano-salts.
[0017] By adopting the above technical solution, the hydroxyl groups on the surface of nano-silica can form hydrogen bonds with molecules and have strong adsorption properties, which can adsorb lipoic acid molecules onto its surface and improve the stability of lipoic acid.
[0018] The surface of nano-titanium oxide has active sites and many pores. These active sites and pores have a strong adsorption capacity for lipoic acid molecules, which will adsorb onto the surface of nano-titanium oxide to form stable lipoic acid nanoparticles.
[0019] Nano starch is a drug carrier that is inexpensive, biocompatible, and biodegradable. Due to its small particle size and large free surface area, nano starch has high colloidal stability and excellent adsorption properties, thus exhibiting strong adsorption of lipoic acid molecules.
[0020] During the vaporization process, nano-salts form a strongly adhering solid magnetic film layer covered with hundreds of millions of nano-sized needles, which can actively adsorb lipoic acid nanoparticles and have strong adsorption properties.
[0021] In one specific implementation, the nanoparticles have a particle size of 10-20 nm and a specific surface area of 200-300 m². 2 / g, wherein the nano-salt is nano-alumina.
[0022] By employing the above technical solution, as the particle size continuously decreases, the specific surface area of the nanoparticles increases dramatically. This high specific surface area leads to an increase in the number of atoms on the particle surface, resulting in a rapid increase in surface energy and surface binding energy. Due to the increased number of atoms on the particle surface, insufficient atomic coordination, and high surface energy, the surface atoms possess high chemical activity and are extremely unstable, readily combining with other atoms. Therefore, selecting appropriate nanoparticle size and specific surface area allows lipoic acid molecules to easily adsorb onto the surface, thereby improving the stability of lipoic acid.
[0023] The surface of nano-alumina has numerous active sites that can chemically react with lipoic acid. At the same time, its surface has a micro-nano structure, forming many channels and micropores of different sizes, which can further increase the surface area of alumina and enhance its adsorption capacity, adsorbing lipoic acid molecules onto its surface and improving the stability of lipoic acid.
[0024] In one specific implementation, in the step of preparing thioctic acid nanoparticles, the volume ratio of the thioctic acid solution to the nanocarrier solution is (70-80):(6-10).
[0025] By adopting the above technical solution and optimizing the mass ratio of thioctic acid solution to nanocarrier solution, the coating rate of thioctic acid molecules on the surface of nanoparticles can be increased, thereby improving the stability of thioctic acid.
[0026] In one specific implementation, in the step of preparing thioctic acid nanoparticles, the thioctic acid solution is added dropwise to the nanocarrier solution at a rate of 2-5 ml / min and stirred for 18-24 h.
[0027] By employing the above-described technical solution, the combination of dropping speed and stirring time can influence the contact time and frequency between lipoic acid and nanoparticles. Appropriate conditions help lipoic acid molecules interact with the nanoparticle surface within a suitable timeframe, thereby achieving better coating.
[0028] Appropriate stirring time can uniformly disperse lipoic acid molecules in nanoparticle suspension, thereby improving the uniformity of coating; stirring too fast or too slow may result in uneven dispersion of lipoic acid in the solution.
[0029] Meanwhile, appropriate stirring time can affect the adsorption and repulsion behavior of lipoic acid molecules on the surface of nanoparticles; appropriate stirring time helps to prevent excessive aggregation of lipoic acid molecules on the surface of nanoparticles, thereby achieving a better coating effect.
[0030] In one specific implementation, in the step of preparing the cured thioctic acid nanoparticles, the temperature during the heat treatment is 60-100℃ and the time is 10-30min.
[0031] By employing the above-mentioned technical solution, appropriate temperature can influence the reaction rate during the curing process; higher temperatures generally promote the reaction rate, helping to form a more stable coating structure in a relatively short time. Temperature can affect the conformation of the coating molecules, thereby affecting their adsorption and coating efficiency on the nanocarrier surface; different temperatures may result in different conformations of the coating, which may affect its distribution and interactions on the carrier surface. Appropriate curing temperatures can promote cross-linking, bonding, or other interactions between the coating and the nanocarrier; these chemical reactions help improve the stability of the coating on the carrier surface.
[0032] The curing time determines the degree of interaction between the coating and the nanocarrier; an appropriate curing time ensures sufficient reaction to form a stable coating layer. A suitable curing time allows for cross-linking between coating molecules or to the carrier surface, resulting in a denser structure and improved coating stability. Different curing times achieve different degrees of curing. Shorter curing times may result in unreacted coating molecules remaining, while longer curing times may lead to over-curing, affecting the dispersibility and stability of the coating.
[0033] In one specific implementation, in the step of preparing the cured thioctic acid nanoparticles, the chemical crosslinking method refers to modifying the thioctic acid nanoparticles with a chemical crosslinking agent, wherein the chemical crosslinking agent includes one of glutaraldehyde, carboxylic acid crosslinking agent, and dianhydride.
[0034] By adopting the above technical solution, the lipoic acid nanoparticles are linked by chemical bonds to form a cross-linked network, thereby preventing the lipoic acid molecules adsorbed on the surface of the nanoparticles from falling off and improving the adsorption effect of lipoic acid on the surface of the nanoparticles.
[0035] In one specific implementation, the purification and preparation step of the lipoic acid nanoparticles involves: separating the solidified lipoic acid nanoparticles from the solvent by centrifugation at a speed of 10,000-15,000 rpm; washing the separated lipoic acid nanoparticles with acetone 1-3 times; and then washing them with deionized water 3 times to remove residual organic solvents and impurities.
[0036] By adopting the above technical solution, the high-speed centrifugal separation method not only has a fast separation speed and high separation efficiency, but also removes the solvent more thoroughly, which can improve the purity of lipoic acid nanoparticles and increase the coating rate of lipoic acid on nanoparticles.
[0037] Secondly, this application provides lipoic acid nanoparticles, employing the following technical solution:
[0038] A lipoic acid nanoparticle was prepared using the method described above.
[0039] In summary, this application includes at least one of the following beneficial technical effects:
[0040] 1. This application uses nanoparticles as a carrier for lipoic acid, adsorbing lipoic acid onto the surface of the nanoparticles, thereby protecting the lipoic acid molecules and effectively reducing the influence of light and temperature on lipoic acid, thus improving the stability of lipoic acid.
[0041] 2. The optimized rate of lipoic acid solution being added to the nanocarrier solution and the stirring time in this application help to allow lipoic acid molecules to interact with the surface of nanoparticles within a suitable time, thereby achieving better coating;
[0042] 3. In the curing process, this application optimizes the temperature and time during heat treatment. Appropriate temperature can affect the reaction rate; higher temperature usually promotes the reaction rate, which helps to form a more stable coating structure in a relatively short time, improves the coating rate, and thus further improves the stability of thioctic acid. Detailed Implementation
[0043] The following embodiments provide a further detailed description of this application.
[0044] Example
[0045] Example 1
[0046] This embodiment discloses a method for preparing lipoic acid nanoparticles, specifically including the following steps:
[0047] S1, add 70g of lipoic acid powder to 1L of organic solution formed by mixing 833ml of ethanol and 167ml of dimethyl sulfoxide, stir to completely dissolve lipoic acid in organic solvent, and obtain 70g / L lipoic acid solution.
[0048] S2, with 6 mg particles having a diameter of 10 nm and a specific surface area of 300 m² 2 / g of nano-silica was added to 1ml of deionized water and stirred to disperse the nano-silica in the deionized water, resulting in a 6mg / ml nano-carrier solution.
[0049] S3, 70 ml of the above thioctic acid solution was added dropwise to the above 6 ml nanocarrier solution at a rate of 2 ml / min, and stirred for 24 h to form thioctic acid nanoparticles;
[0050] S4. The above-mentioned thioctic acid nanoparticles are heat-treated at a temperature of 60°C for 30 minutes to solidify thioctic acid molecules on the surface of the nanoparticles, forming solidified thioctic acid nanoparticles.
[0051] S5. Separate the cured 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 repeatedly wash them three times with deionized water.
[0052] Example 2
[0053] The difference between this embodiment and Embodiment 1 is that, in S1, 70g of lipoic acid powder is added to a 1L organic solution formed by mixing 818ml of ethanol and 182ml of dimethyl sulfoxide, and the mixture is stirred to completely dissolve the lipoic acid in the organic solvent, resulting in a 70g / L lipoic acid solution.
[0054] Example 3
[0055] The difference between this embodiment and Example 1 is that, in S1, 70g of lipoic acid powder is added to a 1L organic solution formed by mixing 937.5ml of ethanol and 62.5ml of dimethyl sulfoxide, and stirred to completely dissolve the lipoic acid in the organic solvent to obtain a 70g / L lipoic acid solution.
[0056] Example 4
[0057] The difference between this embodiment and embodiment 2 is that, in S1, 75g of lipoic acid powder is added to a 1L organic solution formed by mixing 818ml of ethanol and 182ml of dimethyl sulfoxide, and stirred to completely dissolve the lipoic acid in the organic solvent to obtain a 75g / L lipoic acid solution.
[0058] Example 5
[0059] The difference between this embodiment and embodiment 2 is that, in S1, 80g of lipoic acid powder is added to a 1L organic solution formed by mixing 818ml of ethanol and 182ml of dimethyl sulfoxide, and stirred to completely dissolve the lipoic acid in the organic solvent to obtain an 80g / L lipoic acid solution.
[0060] Example 6
[0061] The difference between this embodiment and embodiment 4 is that, in S2, 8 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano-silica was added to 1ml of deionized water and stirred to disperse the nano-silica in the deionized water, resulting in an 8mg / ml nano-carrier solution.
[0062] Example 7
[0063] The difference between this embodiment and Embodiment 4 is that, in S2, 10 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano-silica was added to 1ml of deionized water and stirred to disperse the nano-silica in the deionized water, resulting in a 10mg / ml nano-carrier solution.
[0064] Example 8
[0065] The difference between this embodiment and Embodiment 6 is that, in S2, 8 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano-silica was added to 1ml of deionized water, and ultrasonic treatment was performed to disperse the nano-silica in the deionized water, resulting in an 8mg / ml nano-carrier solution.
[0066] Example 9
[0067] The difference between this embodiment and embodiment 6 is that, in S2, 8 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano-titanium oxide was added to 1ml of deionized water and stirred to disperse the nano-titanium oxide in the deionized water, resulting in an 8mg / ml nano-carrier solution.
[0068] Example 10
[0069] The difference between this embodiment and Embodiment 6 is that, in S2, 8 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano-alumina was added to 1ml of deionized water and stirred to disperse the nano-alumina in the deionized water, resulting in an 8mg / ml nano-carrier solution.
[0070] Example 11
[0071] The difference between this embodiment and Embodiment 6 is that, in S2, 8 mg particles with a diameter of 10 nm and a specific surface area of 300 m² are used. 2 / g of nano starch was added to 1ml of deionized water and stirred to disperse the nano starch in the deionized water, resulting in an 8mg / ml nano carrier solution.
[0072] Example 12
[0073] The difference between this embodiment and embodiment 6 is that, in S2, 8 mg particles with a diameter of 20 nm and a specific surface area of 200 m² are used. 2 / g of nano-silica was added to 1ml of deionized water and stirred to disperse the nano-silica in the deionized water, resulting in an 8mg / ml nano-carrier solution.
[0074] Example 13
[0075] The difference between this embodiment and embodiment 6 is that, in step S3, 75 ml of the above-mentioned thioctic acid solution is added dropwise to the above-mentioned 8 ml nanocarrier solution at a rate of 2 ml / min, and stirred for 24 h to form thioctic acid nanoparticles.
[0076] Example 14
[0077] The difference between this embodiment and embodiment 6 is that, in step S3, 80 ml of the above-mentioned thioctic acid solution is added dropwise to the above-mentioned 10 ml nanocarrier solution at a rate of 2 ml / min, and stirred for 24 h to form thioctic acid nanoparticles.
[0078] Example 15
[0079] The difference between this embodiment and Embodiment 13 is that, in S3, 75 ml of the above-mentioned thioctic acid solution is added dropwise to the above-mentioned 8 ml nanocarrier solution at a rate of 5 ml / min, and stirred for 18 h to form thioctic acid nanoparticles.
[0080] Example 16
[0081] The difference between this embodiment and embodiment 13 is that, in S4, the above-mentioned thioctic acid nanoparticles are heat-treated at a temperature of 100°C for 10 minutes to solidify the thioctic acid molecules on the surface of the nanoparticles, forming solidified thioctic acid nanoparticles.
[0082] Example 17
[0083] The difference between this embodiment and embodiment 13 is that, in step S4, 10g of glutaraldehyde is added to the above 100g of thioctic acid nanoparticles for modification treatment to obtain solidified thioctic acid nanoparticles.
[0084] Example 18
[0085] The difference between this embodiment and Example 17 is that, in S4, 10g of N-hydroxysuccinimide (carboxylic acid crosslinking agent) is added to the above 100g of thioctic acid nanoparticles for modification treatment to obtain cured thioctic acid nanoparticles.
[0086] Example 19
[0087] The difference between this embodiment and Example 17 is that, in S4, 10g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (carbonic dianhydride) is added to the above 100g of thioctic acid nanoparticles for modification treatment to obtain solidified thioctic acid nanoparticles.
[0088] Example 20
[0089] The difference between this embodiment and embodiment 17 is that, in step S5, the cured lipoic acid nanoparticles are separated from the solvent at a rotation speed of 15000 rpm; then the separated lipoic acid nanoparticles are washed with acetone three times and then repeatedly washed with deionized water three times.
[0090] Example 21
[0091] The difference between this embodiment and embodiment 17 is that, in step S5, the cured thioctic acid nanoparticles are filtered and dried at 120°C to separate the thioctic acid nanoparticles from the solvent; then the separated thioctic acid nanoparticles are washed three times with acetone and then repeatedly washed three times with deionized water.
[0092] Comparative Example
[0093] Comparative Example 1
[0094] The difference between this comparative example and Example 1 is that the lipoic acid CAS number is 62-46-4.
[0095] Comparative Example 2
[0096] The difference between this comparative example and Example 13 is that, in S3, 70 ml of the above-mentioned thioctic acid solution was added dropwise to the above-mentioned 6 ml nanocarrier solution at a rate of 1 ml / min, and stirred for 30 h to form thioctic acid nanoparticles.
[0097] Comparative Example 3
[0098] The difference between this comparative example and comparative example 13 is that, in S3, 70 ml of the above thioctic acid solution was added dropwise to the above 6 ml nanocarrier solution at a rate of 6 ml / min, and stirred for 17 h to form thioctic acid nanoparticles.
[0099] Comparative Example 4
[0100] The difference between this comparative example and comparative example 13 is that, in S4, the above-mentioned thioctic acid nanoparticles are heat-treated at a temperature of 50°C for 40 minutes to solidify the thioctic acid molecules on the surface of the nanoparticles, forming solidified thioctic acid nanoparticles.
[0101] Comparative Example 5
[0102] The difference between this comparative example and comparative example 13 is that, in S4, the above-mentioned thioctic acid nanoparticles are heat-treated at a temperature of 110°C for 5 minutes to solidify the thioctic acid molecules on the surface of the nanoparticles, forming solidified thioctic acid nanoparticles.
[0103] Performance testing
[0104] 1. Stability
[0105] Stability testing was conducted in accordance with the guidelines for stability testing and methodological validation in Part IV of the 2022 edition of the Chinese Pharmacopoeia.
[0106] The thioctic acid particles prepared in Examples 1-21 and Comparative Examples 1-5 were placed in suitable open containers and spread into a thin layer. The loose raw material drug was spread into a thin layer of 10 mm thickness. The following experiment was carried out: the open containers were placed in a light box equipped with fluorescent lamps (40-50℃) and placed under an illuminance of 4500±500 lx for 10 days. Samples were taken on the 10th day to observe whether the thioctic acid emitted a pungent odor. The results are recorded in Table 1.
[0107] 2. Coverage rate
[0108] The coating efficiency of the lipoic acid nanoparticles prepared in Examples 1-21 and Comparative Examples 2-5 was calculated as follows: coating efficiency = (mass of lipoic acid nanoparticles - mass of nanoparticles used) / lipoic acid powder used × 100%. The results are recorded in Table 1.
[0109] Table 1 Performance test data of Examples 1-21 and Comparative Examples 1-5
[0110]
[0111]
[0112] Referring to Table 1, and in conjunction with Example 1 and Comparative Example 1, it can be seen that the lipoic acid nanoparticles prepared by the method of this application produce lipoic acid with significantly better stability compared to ordinary lipoic acid. The preparation method of this application uses nanoparticles as a carrier for lipoic acid, adsorbing the lipoic acid onto the surface of the nanoparticles. This protects the lipoic acid molecules from the nanoparticles, effectively reducing the impact of light and improving the stability of lipoic acid.
[0113] Referring to Table 1, and in conjunction with Examples 13 and 15 and Comparative Examples 2-3, it can be seen that optimizing the rate of lipoic acid solution dropwise addition to the nanoparticle carrier solution and the stirring time during the preparation of lipoic acid nanoparticles can improve the coating efficiency of lipoic acid and the stability of the prepared lipoic acid nanoparticles. The combination of dropwise addition rate and stirring time can affect the contact time and frequency between lipoic acid and nanoparticles. Appropriate conditions help to enable lipoic acid molecules to interact with the nanoparticle surface within a suitable time, thereby achieving a higher coating efficiency. Appropriate stirring can uniformly disperse lipoic acid molecules in the nanoparticle suspension, thereby improving the uniformity of coating; stirring too fast or too slow may lead to uneven dispersion of lipoic acid in the solution. At the same time, stirring can affect the adsorption and repulsion behavior of lipoic acid molecules on the nanoparticle surface; appropriate stirring helps to prevent excessive aggregation of lipoic acid molecules on the nanoparticle surface, thereby achieving a better coating effect and improving the stability of lipoic acid nanoparticles.
[0114] Referring to Table 2, and in conjunction with Examples 13 and 16 and Comparative Examples 4-5, it can be seen that this application can improve the coating properties and stability of the prepared thioctic acid nanoparticles by optimizing the temperature and time during heat treatment. During the curing process, appropriate temperature can affect the reaction rate; higher temperatures generally promote the reaction rate, helping to form a more stable coating structure in a relatively short time. Temperature can affect the conformation of the coating molecules, thereby affecting their adsorption and coating rate on the nanocarrier surface; different temperatures may result in different conformations of the coating, which may affect its distribution and interaction on the carrier surface. Appropriate curing temperature can promote crosslinking, bonding, or other interactions between the coating and the nanocarrier; these chemical reactions help improve the stability of the coating on the carrier surface.
[0115] The curing time determines the degree of interaction between the coating and the nanocarrier; an appropriate curing time ensures sufficient reaction to form a stable coating layer. A suitable curing time allows for cross-linking between coating molecules or to the carrier surface, resulting in a denser structure and improved coating stability. Different curing times achieve different degrees of curing. Shorter curing times may result in unreacted coating molecules remaining, while longer curing times may lead to over-curing, affecting the dispersibility and stability of the coating.
[0116] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A method for preparing lipoic acid nanoparticles, characterized in that: Includes the following steps: Preparation of lipoic acid solution: Add lipoic acid powder to an organic solvent and stir to dissolve to form a 70-80 g / L lipoic acid solution; Preparation of nanocarrier solution: Nanoparticles are added to a solvent to disperse the nanoparticles in the solvent, resulting in a nanocarrier solution with a concentration of 6-10 mg / ml. Preparation of lipoic acid nanoparticles: Lipoic acid solution is added dropwise to nanocarrier solution and stirred to form lipoic acid nanoparticles; Curing lipoic acid nanoparticles: The lipoic acid nanoparticles are cured by heat treatment; Purification of lipoic acid nanoparticles: The solidified lipoic acid nanoparticles are separated into lipoic acid nanoparticles and solvent by centrifugation or filtration. The separated lipoic acid nanoparticles are then washed to remove residual organic solvents and impurities. In the step of preparing the thioctic acid solution, the organic solvent is a mixture of ethanol and dimethyl sulfoxide in a mass ratio of (5-15):1; In the step of preparing lipoic acid nanoparticles, the lipoic acid solution is added dropwise to the nanocarrier solution at a rate of 2-5 ml / min and stirred for 18-24 h. In the step of preparing the nanocarrier solution, the nanoparticles are either nano-silica or nano-titanium oxide. In the preparation step of the solidified thioctic acid nanoparticles, the temperature during the heat treatment is 60-100℃ and the time is 10-30min.
2. The method for preparing lipoic acid nanoparticles according to claim 1, characterized in that: The nanoparticles have a particle size of 10-20 nm and a specific surface area of 200-300 m². 2 / g.
3. The method for preparing lipoic acid nanoparticles according to claim 1, characterized in that: In the step of preparing thioctic acid nanoparticles, the volume ratio of the thioctic acid solution to the nanocarrier solution is (70-80):(6-10).
4. The method for preparing lipoic acid nanoparticles according to claim 1, characterized in that: In the purification and preparation steps of the lipoic acid nanoparticles: the solidified lipoic acid nanoparticles are centrifuged at a speed of 10000-15000 rpm to separate the lipoic acid nanoparticles and solvent. The separated lipoic acid nanoparticles are then washed with acetone 1-3 times and then washed with deionized water 3 times to remove residual organic solvents and impurities.