Nanogel for astaxanthin delivery and preparation method thereof
The nanogel formed by combining lysozyme and carboxymethyl chitosan solves the problem of poor stability of astaxanthin in the gastrointestinal environment, achieves targeted release and high-efficiency antioxidant effect of astaxanthin, and improves bioavailability.
Patent Information
- Application Number
- CN202610290848.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-11
- Publication Date
- 2026-05-05
AI Technical Summary
Existing astaxanthin delivery systems have poor stability in the gastrointestinal environment, resulting in low bioavailability in vivo and making it difficult to achieve targeted release and fully exert antioxidant effects.
The nanogel formed by lysozyme and carboxymethyl chitosan utilizes its pH-responsive properties to maintain stability in the gastrointestinal environment and achieve targeted release in the intestinal environment. It also protects astaxanthin from the effects of light, heat and oxygen through encapsulation and composite network.
It significantly improved the stability and bioavailability of astaxanthin, enhanced its antioxidant effect in vivo, and achieved efficient delivery of nanogels through a simple and green preparation process.
Smart Images
Figure CN121971376A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to nanomedicine delivery systems, and more particularly to a nanogel for astaxanthin delivery and its preparation method. Background Technology
[0002] Astaxanthin is a natural carotenoid widely found in certain algae, shrimp, crabs, and fish. Its exceptional antioxidant properties have led to its widespread application in the health industry. Studies have shown that astaxanthin's antioxidant activity is 6000 times that of vitamin C and 110 times that of vitamin E. It effectively scavenge free radicals in the body, slows down the aging process, and has anti-cancer and neuroprotective effects. However, due to the multiple conjugated double bonds in its molecular structure, astaxanthin is susceptible to degradation by light, heat, and oxygen, resulting in reduced bioavailability. Furthermore, as a hydrophobic molecule, astaxanthin has low absorption efficiency in the body, and its bioavailability is easily affected by the gastrointestinal environment when administered orally.
[0003] Currently, various astaxanthin delivery systems have been studied, mainly including liposomes, microcapsules, and nanoparticles. However, although these carrier systems have played a role in enhancing the stability and bioavailability of astaxanthin, their targeting is still insufficient, making it difficult to fully realize the antioxidant effects of astaxanthin. Especially when taken orally, existing systems have poor stability in the gastrointestinal environment, resulting in ineffective release and absorption. Therefore, there is an urgent need for a new delivery system that can effectively protect astaxanthin and achieve targeted release in the gastrointestinal tract to improve its bioavailability. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a nanogel for astaxanthin delivery and its preparation method. This nanogel is formed using a composite of lysozyme and carboxymethyl chitosan, and utilizes its unique pH-responsive properties to exhibit good stability and release characteristics in the gastrointestinal environment. The preparation method of this invention not only effectively improves the stability of astaxanthin but also enables its targeted release in the gastrointestinal tract, thereby enhancing the bioavailability and antioxidant effects of astaxanthin.
[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:
[0006] This invention provides a nanogel for astaxanthin delivery and a method for preparing the same, comprising the following:
[0007] (1) A nanogel for astaxanthin delivery, the nanogel being composed of a lysozyme-carboxymethyl chitosan complex and loaded with astaxanthin, having pH responsiveness, and undergoing structural swelling or dissociation in the pH range of 5.0 to 7.4;
[0008] (2) A method for preparing nanogels for astaxanthin delivery, comprising the following steps: dissolving lysozyme and carboxymethyl chitosan in ultrapure water to obtain two solutions, and dissolving astaxanthin in ethanol to obtain an astaxanthin solution; adding the lysozyme solution to the carboxymethyl chitosan solution and mixing, adjusting the pH of the mixed solution with sodium hydroxide standard solution to form a lysozyme-carboxymethyl chitosan complex; adding the astaxanthin solution to the complex and mixing, heating to obtain a reaction mixture; homogenizing the reaction mixture, cooling and lyophilizing to obtain a lyophilized astaxanthin nanogel.
[0009] Based on the above technical solutions, the lysozyme-carboxymethyl chitosan composite nanogel system constructed in this invention has significant advantages and broad application prospects. This system effectively isolates external factors such as light, heat, and oxygen through encapsulation and a composite network, significantly improving and extending the stability and shelf life of astaxanthin. Simultaneously, it exhibits a clear pH response, maintaining structural stability in the gastric environment (pH≈2) while swelling and releasing the drug in the intestinal environment (pH≈7.4), meeting the targeted release requirements for oral administration. The synergistic effect of lysozyme and carboxymethyl chitosan not only improves the biocompatibility of the carrier but also enhances the antioxidant activity of the system, thereby more efficiently scavenging reactive oxygen species and protecting cells from oxidative damage. Furthermore, the preparation process of this invention is simple, green, and easily scaled up industrially. The resulting nanogel has good dispersibility and a complete structure, making it suitable not only for the protection and controlled release of astaxanthin but also for the delivery and long-term stable preservation of other hydrophobic drugs, nutrients, or cosmetic active ingredients. Attached Figure Description
[0010] Figure 1 Images of the scanning electron microscope (SEM) and transmission electron microscope (TEM) used for astaxanthin delivery nanogels;
[0011] Figure 2 The graph shows the changes in particle size, PDI, and potential of the nanogel used for astaxanthin delivery as a function of heating temperature, NaCl concentration, and storage time.
[0012] Figure 3 The graph shows the changes in particle size, polydispersity index (PDI), and zeta potential of the nanogel used for astaxanthin delivery during a simulated gastrointestinal digestion process.
[0013] Figure 4 This graph shows the change in the cumulative release rate of astaxanthin from the nanogel used for astaxanthin delivery during a simulated gastrointestinal digestion process.
[0014] Figure 5 The graph shows the scavenging rates of hydroxyl radicals and ABTS radicals for astaxanthin delivery nanogels.
[0015] Figure 6The figure shows the effect of astaxanthin delivery nanogels on the survival rate of cells with H2O2-induced oxidative damage. Detailed Implementation
[0016] The technical features, objectives, and beneficial effects of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.
[0017] The following is a description through specific embodiments.
[0018] Example 1
[0019] Lysozyme and carboxymethyl chitosan were dissolved separately in ultrapure water to prepare solutions of 1 mg / mL. The lysozyme and carboxymethyl chitosan were then mixed in a 1:1 ratio, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. An ethanol solution of astaxanthin (5.0 mg / mL) was added to the nano-mixture at a volume ratio of 1:25, and the mixture was heated at 80°C for 40 min. Following this, homogenization was performed at 12000 rpm for 5 min to form a nanogel encapsulating astaxanthin. Finally, the cooled nanogel was lyophilized to obtain the astaxanthin nanogel.
[0020] The astaxanthin nanogel prepared in Example 1 obtained above was characterized by a particle size of about 198 nm, a polydispersity index of about 0.47, and a zeta potential of about -30.16 mV by a laser particle size analyzer.
[0021] Example 2
[0022] Lysozyme and carboxymethyl chitosan were dissolved separately in ultrapure water to prepare solutions of 1 mg / mL. The lysozyme and carboxymethyl chitosan were then mixed at a ratio of 5:4, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. An ethanol solution of astaxanthin (concentration 5.0 mg / mL) was added to the nano-mixture at a volume ratio of 1:25, and the mixture was heated at 80°C for 40 min, followed by homogenization at 12000 rpm for 5 min to form a nanogel encapsulating astaxanthin. Finally, the cooled nanogel was lyophilized to obtain astaxanthin nanogel.
[0023] The astaxanthin nanogel prepared in Example 2 obtained above was characterized by a particle size of about 240 nm, a polydispersity index of about 0.36, and a zeta potential of about -30.38 mV by a laser particle size analyzer.
[0024] Example 3
[0025] Lysozyme and carboxymethyl chitosan were dissolved separately in ultrapure water to prepare solutions of 1 mg / mL. The lysozyme and carboxymethyl chitosan were then mixed at a ratio of 5:3, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. An ethanol solution of astaxanthin (5.0 mg / mL) was added to the nano-mixture at a volume ratio of 1:25, and the mixture was heated at 80°C for 40 min, followed by homogenization at 12000 rpm for 5 min to form a nanogel encapsulating astaxanthin. Finally, the cooled nanogel was lyophilized to obtain astaxanthin nanogel.
[0026] The astaxanthin nanogel prepared in Example 3 above was characterized by a particle size of about 208 nm, a polydispersity index of about 0.27, and a zeta potential of about -26.73 mV by a laser particle size analyzer.
[0027] Example 4
[0028] Lysozyme and carboxymethyl chitosan were dissolved separately in ultrapure water to prepare solutions of 1 mg / mL. The lysozyme and carboxymethyl chitosan were then mixed at a ratio of 5:2, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. An ethanol solution of astaxanthin (5.0 mg / mL) was added to the nano-mixture at a volume ratio of 1:25, and the mixture was heated at 80°C for 40 min, followed by homogenization at 12000 rpm for 5 min to form a nanogel encapsulating astaxanthin. Finally, the cooled nanogel was lyophilized to obtain astaxanthin nanogel (NGs-Ast).
[0029] The astaxanthin nanogel prepared in Example 4 above was characterized by a particle size of about 179 nm, a polydispersity index of about 0.24, and a zeta potential of about -22.01 mV by a laser particle size analyzer.
[0030] Example 5
[0031] Lysozyme and carboxymethyl chitosan were dissolved separately in ultrapure water to prepare solutions of 1 mg / mL. The lysozyme and carboxymethyl chitosan were then mixed at a ratio of 5:1, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. An ethanol solution of astaxanthin (5.0 mg / mL) was added to the nano-mixture at a volume ratio of 1:25, and the mixture was heated at 80°C for 40 min. Homogenization was then performed at 12000 rpm for 5 min to form a nanogel encapsulating astaxanthin. Finally, the cooled nanogel was lyophilized to obtain astaxanthin nanogel.
[0032] The astaxanthin nanogel prepared in Example 5 obtained above was characterized by a particle size of about 314 nm, a polydispersity index of about 0.21, and a zeta potential of about -26.11 mV by a laser particle size analyzer.
[0033] Comparative Example 1: Free Astaxanthin (Ast)
[0034] Astaxanthin was dissolved in an ethanol solution to obtain a free astaxanthin solution.
[0035] Comparative Example 2: Nanogels (NGs) without astaxanthin loading
[0036] Lysozyme and carboxymethyl chitosan were separately dissolved in ultrapure water to prepare 1 mg / mL solutions. The lysozyme and carboxymethyl chitosan were then mixed in a 5:2 ratio, and the pH was adjusted to 8 using HCl standard solution to obtain a nano-mixture of lysozyme and carboxymethyl chitosan. This nano-mixture was heated at 80 °C for 40 min, followed by homogenization at 12000 r / min for 5 min. Finally, the cooled nanogel was lyophilized to obtain astaxanthin-free nanogels.
[0037] Comparative Example 3: Vitamin C (Vc)
[0038] Vitamin C is dissolved in the extract to obtain a vitamin C solution.
[0039] Product Characterization
[0040] The astaxanthin nanogels prepared in Example 4 were characterized using scanning electron microscopy and transmission electron microscopy.
[0041] like Figure 1 As shown, the astaxanthin nanogel is well dispersed, has a good particle size distribution, and is spherical in shape.
[0042] Performance testing
[0043] The astaxanthin nanogel prepared in Example 4 was evaluated for its stability under high temperature, NaCl concentration and storage conditions.
[0044] like Figure 2 As shown, the particle size, PDI, and potential of the astaxanthin nanogel did not change significantly at different temperatures (50–90 °C), different NaCl concentrations (50–200 mmol / L), and during a storage period of 25 days, indicating that the cross-linked structure within the nanogel was very stable.
[0045] The gastrointestinal stability of the astaxanthin nanogel prepared in Example 4 was evaluated, and the astaxanthin release of the astaxanthin nanogel prepared in Example 4 and the free astaxanthin in Comparative Example 1 was evaluated.
[0046] like Figure 3 and Figure 4 As shown, free astaxanthin is rapidly released in gastric juice, while the release of astaxanthin nanogels increases in intestinal juice. The release rate of astaxanthin nanogels in digestive juices is significantly higher than that of free astaxanthin. During simulated gastrointestinal digestion, the particle size of the astaxanthin nanogels initially increases and then decreases, while the zeta potential initially decreases and then increases. This indicates that the astaxanthin nanogels protect astaxanthin from degradation in the gastric environment and release it in the intestinal environment, demonstrating good targeting properties.
[0047] The astaxanthin nanogel prepared in Example 4, the free astaxanthin in Comparative Example 1, the unloaded astaxanthin nanogel in Comparative Example 2, and the vitamin C in Comparative Example 3 were evaluated for hydroxyl radical and ABTS radical scavenging.
[0048] like Figure 5 As shown, the astaxanthin nanogel exhibits a hydroxyl radical scavenging rate of 91.53% and an ABTS radical scavenging rate of 94.17%, which is significantly higher than that of free astaxanthin in Comparative Example 1 (28.59%, 25.45%) and the unloaded astaxanthin nanogel in Comparative Example 2 (43.99%, 71.17%). Its scavenging rate is similar to that of vitamin C (94.58%, 99.1%), confirming that the astaxanthin nanogel possesses enhanced hydroxyl radical and ABTS radical scavenging capabilities compared to free astaxanthin.
[0049] The protective effect of astaxanthin nanogels against H2O2-induced oxidative damage was evaluated in Example 4.
[0050] like Figure 6 As shown, at different concentrations ranging from 0.0625 to 1 mg / mL, astaxanthin nanogels can improve the survival rate of cells damaged by H2O2-induced oxidative stress and alleviate the damage caused by H2O2 to cells.
[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A nanogel for astaxanthin delivery, characterized in that, The nanogel is composed of a lysozyme-carboxymethyl chitosan complex and loaded with astaxanthin. It is pH responsive and undergoes structural swelling or dissociation in the pH range of 5.0 to 7.
4.
2. The nanogel according to claim 1, characterized in that, The lysozyme has an enzyme activity of ≥2000 U / mg and the concentration of the lysozyme solution is 1 mg / mL.
3. The nanogel according to claim 2, characterized in that, The degree of substitution of the carboxymethyl chitosan is ≥80%, and the concentration of the carboxymethyl chitosan solution is 1 mg / mL.
4. The nanogel according to claim 3, characterized in that, The purity of the astaxanthin was 96%, and the concentration of the astaxanthin solution was 5.0 mg / mL.
5. A method for preparing nanogels for astaxanthin delivery, characterized in that, Includes the following steps: (1) Lysozyme and carboxymethyl chitosan were dissolved in ultrapure water to prepare two solutions, and astaxanthin was dissolved in ethanol to prepare an astaxanthin solution. (2) Add lysozyme solution to carboxymethyl chitosan solution and mix. Use sodium hydroxide standard solution to adjust the pH of the mixed solution to form lysozyme-carboxymethyl chitosan complex. (3) Add the astaxanthin solution to the complex, mix, and heat to obtain the reaction mixture; (4) The reaction mixture was homogenized, cooled and then freeze-dried to obtain astaxanthin nanogel freeze-dried product.
6. The nanogel according to claim 5, characterized in that, The volume ratio of the lysozyme solution to the carboxymethyl chitosan solution in step (1) is 5:
2.
7. The nanogel according to claim 6, characterized in that, The sodium hydroxide standard solution used in step (2) makes the pH of the mixed solution 8.
0.
8. The nanogel according to claim 7, characterized in that, In step (3), the volume ratio of astaxanthin solution to complex is 1:25, the heating temperature is 80 ℃, and the heating time is 40 min.
9. The nanogel according to claim 8, characterized in that, In step (4), the homogenization speed is 12000 r / min and the homogenization time is 5 min.