Double network hydrogel and preparation method and application thereof

Abstract

The present application relates to the field of cosmetics, in particular to a double-network hydrogel, a preparation method and application thereof.The first network structure of the hydrogel disclosed by the present application is calcium ion cross-linked sodium alginate, and the second network structure is potassium ion cross-linked carrageenan.The preparation method provided by the present application can effectively overcome the defects of single-network structure hydrogel, such as low strength, large brittleness, easy to break, poor fatigue resistance and easy to over-swelling, and significantly improve the mechanical strength, tensile property, fracture toughness and crack propagation resistance.In addition, the hydrogel is composed of natural polymers, and is not easy to cause allergy and irritation, and is suitable for preparing cosmetics such as facial mask and eye mask.Meanwhile, the preparation method is simple and efficient, and various active ingredients can be loaded according to requirements.

Description

Technical Field

[0001] This invention relates to the field of cosmetics, and more particularly to dual-network hydrogels, their preparation methods, and applications. Background Technology

[0002] The core requirement for cosmetic eye masks is to adapt to the thin, sensitive, easily dehydrated, and contoured skin around the eyes, while ensuring the safe and efficient delivery of active ingredients. Hydrogels, with their structural properties highly compatible with this requirement, have gradually replaced traditional membrane fabrics such as non-woven fabrics and silk, becoming the core matrix for high-end functional eye masks. Hydrogels possess a three-dimensional network structure and high water content, resembling the extracellular matrix, making them an excellent eye mask matrix. Formed by cross-linking hydrophilic polymers, hydrogels can hold over 90% water, providing a jelly-like texture and continuously hydrating the skin. The network pores of hydrogels effectively hold water and hydrophilic active ingredients, achieving slow release and absorption by the skin through diffusion. Hydrogels, formed from natural polymers through physical cross-linking, effectively reduce irritation to sensitive skin around the eyes, making them suitable as a long-term or frequently used application material.

[0003] Hydrogels can be categorized into single-network and dual-network types based on their network structure. Currently, the core issue with single-network hydrogels is their unidirectional performance, failing to simultaneously meet the complex requirements of eye masks for softness, skin-friendliness, mechanical stability, long-lasting hydration, multi-drug delivery, dynamic adhesion, and low irritation. Dual-network hydrogels, through interpenetration and synergy, achieve a balance and optimization of all core properties, ultimately reaching the ideal state of the eye mask matrix: soft yet not mushy, adheres well without slipping, provides long-lasting hydration, enables multi-drug delivery, offers controlled release and gentle application, and is stable and low-irritation.

[0004] This comprehensive performance enhancement makes dual-network hydrogel the core matrix choice for high-end functional eye masks, especially suitable for multifunctional eye masks with anti-inflammatory, brightening, and soothing properties, and is also the main development direction for hydrogel eye masks in the future. Summary of the Invention

[0005] In view of this, the present invention provides a dual-network hydrogel, its preparation method, and its applications. The first network structure of the hydrogel disclosed in this invention is sodium alginate cross-linked with calcium ions, and the second network structure is carrageenan cross-linked with potassium ions. The preparation method provided by this invention effectively overcomes the defects of single-network hydrogels, such as low strength, high brittleness, easy fracture, poor fatigue resistance, and easy over-swelling, significantly improving mechanical strength, tensile properties, fracture toughness, and crack propagation resistance. Furthermore, this hydrogel is composed of natural polymers, is less likely to cause allergies or irritation, and is suitable for preparing cosmetics such as face masks and eye masks. At the same time, the preparation method is simple and efficient, and can load various active ingredients according to requirements.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a dual-network hydrogel, comprising: a first network and a second network;

[0008] The first network comprises a first anionic polymer crosslinked with a first metal ion, and the second network comprises a second anionic polymer crosslinked with a second metal ion;

[0009] The first anionic polymer and the second anionic polymer are independently selected from: sodium alginate and carrageenan;

[0010] The first metal ion and the second metal ion are independently selected from calcium ions and potassium ions;

[0011] The first anionic polymer and the second anionic polymer may be the same or different;

[0012] The first metal ion and the second metal ion can be the same or different.

[0013] In some embodiments of the present invention, the above-mentioned dual-network hydrogel further includes: a modifying component; the modifying component includes: gelatin and / or xanthan gum.

[0014] In some embodiments of the present invention, in the above-mentioned dual-network hydrogel, the first network contains: calcium ion crosslinked sodium alginate and gelatin; the second network contains: potassium ion crosslinked carrageenan and xanthan gum; the mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum is (10~30):(10~40):(4~8):(2~5).

[0015] In some embodiments of the present invention, the mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum in the above-mentioned dual-network hydrogel is 20:20:6:3 or 10:20:6:3 or 30:20:6:3.

[0016] The present invention also provides a method for preparing the above-mentioned dual-network hydrogel, wherein the gelatin, the sodium alginate, the carrageenan and the xanthan gum are dissolved in a solvent in sequence, and the hydrogel is obtained after pre-crosslinking, coagulation, secondary crosslinking and washing with water;

[0017] The pre-crosslinking uses potassium ions; the secondary crosslinking uses calcium ions.

[0018] In some embodiments of the present invention, in the above preparation method, the potassium ions crosslink the carrageenan; and the calcium ions crosslink the sodium alginate.

[0019] In some embodiments of the present invention, in the above preparation method, the mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum is (10~30):(10~40):(4~8):(2~5).

[0020] In some embodiments of the present invention, in the above preparation method, the mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum is 20:20:6:3 or 10:20:6:3 or 30:20:6:3.

[0021] In some embodiments of the present invention, the solvent in the above preparation method includes: water and / or plant polysaccharide extract.

[0022] In some embodiments of the present invention, the polysaccharide extract in the above preparation method includes one or more of the following: Dendrobium officinale polysaccharide extract (Shikong Xianzhu), Auricularia auricula-judae polysaccharide extract (Jintang), and Coix lacryma-jobi extract (Yiyan Yurun).

[0023] In some embodiments of the present invention, the temperature at which the solvent is dissolved is 50-60°C in the above preparation method.

[0024] The present invention also provides the application of the above-described dual-network hydrogel and / or the dual-network hydrogel obtained by the above preparation method in the preparation of topical skin dressings.

[0025] In some embodiments of the present invention, in the above applications, the topical skin patch has one or more of the following effects: anti-oxidation, whitening, anti-aging, and repair.

[0026] In some embodiments of the present invention, in the above applications, the topical skin dressing includes one or more of the following: face mask, eye mask, neck mask, lip mask, nose mask, and local skin care dressing.

[0027] The present invention also provides a topical skin dressing comprising: the above-described dual-network hydrogel and / or the dual-network hydrogel obtained by the above preparation method, and cosmetically acceptable adjuvants.

[0028] In some embodiments of the present invention, the adjuvant includes one or more of nicotinamide, glutathione, and astaxanthin liposomes.

[0029] The beneficial effects of this invention include:

[0030] The present invention has the following beneficial effects:

[0031] (1) The dual-network structure hydrogel eye mask of the present invention fundamentally solves the contradiction between mechanical strength and flexibility of traditional single-network hydrogel by constructing an interpenetrating structure of "rigid skeleton + flexible dissipation". As a result, it achieves a comprehensive leap in toughness, water retention, sustained release and skin fit. It is a high-performance, multifunctional and customizable ideal eye mask material.

[0032] (2) The dual-network structure hydrogel of the present invention has a rich and dense network structure, which can efficiently load various water-soluble active ingredients and create favorable conditions for the release and absorption of active ingredients. At the same time, the sustained release of the dual-network structure hydrogel can achieve a more stable and long-lasting release, prolong the action time of the active ingredients, and prevent skin allergies caused by violent release.

[0033] (3) The dual-network structure hydrogel of the present invention has a simple composition and is formed by physical cross-linking of natural macromolecules, which is not likely to cause adverse reactions such as allergies.

[0034] (4) The dual-network structure hydrogel of the present invention can be prepared into eye masks, face masks and other related products. Its preparation process is simple and suitable for large-scale production. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0036] Figure 1 Image showing hydrogel of Dendrobium officinale polysaccharide extract (Time-Space Dendrobium);

[0037] Figure 2 Image of hydrogel of Auricularia auricula polysaccharide extract (Auricularia auricula polysaccharide);

[0038] Figure 3 Image showing brown rice and Job's tears extract hydrogel (Job's Skin Nourishing);

[0039] Figure 4 Images showing hydrogels loaded with various active ingredients;

[0040] Figure 5 Image showing a hydrogel prepared using Maclean sodium alginate;

[0041] Figure 6 Images of hydrogels prepared from konjac glucomannan;

[0042] Figure 7 Image showing hydrogel prepared by gellan gel;

[0043] Figure 8 The results of short-term water retention tests for hydrogels with dual-network and single-network structures are shown.

[0044] Figure 9 The results of long-term water loss testing for hydrogels with dual-network and single-network structures are shown.

[0045] Figure 10 The results of skin moisturizing tests for hydrogels with dual-network and single-network structures are shown.

[0046] Figure 11 The swelling ratio test results of dual-network structure hydrogels and single-network structure hydrogels are shown.

[0047] Figure 12 The SEM results of the dual-network structure hydrogel and the single-network structure hydrogel are shown.

[0048] Figure 13 The tensile test results of hydrogels with dual-network structure and hydrogels with single-network structure are shown.

[0049] Figure 14 The compressibility test results of hydrogels with dual-network structure and hydrogels with single-network structure are shown.

[0050] Figure 15 The rheological test results of the dual-network structure hydrogel and the single-network structure hydrogel are shown.

[0051] Figure 16 The results of nicotinamide release rate detection for dual-network hydrogels and single-network hydrogels are shown.

[0052] Figure 17 The results of hemolysis rate detection for the dual-network structure hydrogel are shown. Detailed Implementation

[0053] This invention discloses a dual-network hydrogel, its preparation method, and its applications.

[0054] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0055] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0056] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0057] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0058] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0059] In a first aspect, the present invention provides a dual-network structure hydrogel, wherein the first network layer is sodium alginate cross-linked with calcium ions, and gelatin is added to enhance structural rigidity. The second network layer is carrageenan cross-linked with potassium ions, and xanthan gum is introduced to provide flexibility.

[0060] Secondly, the present invention provides a method for preparing the above-mentioned dual-network structure hydrogel, comprising:

[0061] Gelatin was dissolved in water and heated while stirring until dissolved. Sodium alginate was then added and stirred until homogeneous to obtain the first layer of the network structure. Carrageenan was dissolved in a sodium alginate-gelatin mixed solution, xanthan gum was added to swell and disperse, potassium chloride was added, and the mixture was heated and stirred until fully crosslinked to form the second layer of the network structure. The mixture was poured into molds while still hot and placed in a 4°C refrigerator to cool and solidify. A calcium chloride solution was then added dropwise at room temperature as a crosslinking agent. After crosslinking was complete, the mixture was rinsed with ultrapure water to obtain the double-network hydrogel.

[0062] Thirdly, the dual-network structure hydrogel provided by the present invention can load and release a variety of active ingredients to achieve anti-inflammatory, antioxidant, wrinkle-reducing, anti-aging, moisturizing and repairing effects.

[0063] This invention provides a dual-network structure hydrogel and its preparation method, comprising the following steps:

[0064] (1) Dissolve gelatin in water, heat and stir to dissolve, add sodium alginate and stir evenly to obtain the matrix of the first network structure;

[0065] In some embodiments, the concentration of sodium alginate may be 1-3%.

[0066] In some embodiments, the solvent can be replaced with Dendrobium officinale polysaccharide extract (Shikong Xianzhu), Auricularia auricula-judae polysaccharide extract (Jintang), or brown rice and Job's tears extract (Yiyan Yurun). This allows the plant extracts in these solutions to fully integrate with the hydrogel matrix, improving skin bioavailability.

[0067] In some embodiments, the heating temperature is between 50°C and 60°C. Specifically, it can be any temperature within this range, such as 50, 52, 54, 56, 58, or 60°C.

[0068] In some comparative examples, the mass ratio of sodium alginate to gelatin was 1:0.5, 1:1, 1:2, 1:4, and 1:8. Too little gelatin would result in poor mechanical properties of the hydrogel, while too much would result in high viscosity and low water content of the sol.

[0069] (2) Dissolve carrageenan in the sodium alginate-gelatin mixed solution in (1), add xanthan gum, add potassium chloride and heat and stir to fully crosslink and form a second network structure.

[0070] In some embodiments, active ingredients such as nicotinamide, glutathione, and astaxanthin liposomes are loaded to enable the dual-network structure hydrogel eye mask to have corresponding effects.

[0071] In some embodiments, the heating temperature is between 50°C and 60°C. Specifically, it can be any temperature within this range, such as 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, etc.

[0072] In some comparative examples, the mass ratio of carrageenan to xanthan gum was 1:0.5, 1:1, 1:2, 1:4, and 1:8. Too little xanthan gum will cause the hydrogel to harden and lack flexibility; too much xanthan gum will cause the sol viscosity to increase, resulting in an uneven surface of the hydrogel.

[0073] (3) While the sol in (2) is still hot, pour it into the mold and place it in a refrigerator at 4°C to cool and solidify.

[0074] In some embodiments, the refrigeration time is 5 min to 15 min. The purpose of refrigeration is to allow the sol to solidify, which facilitates subsequent cross-linking.

[0075] (4) Take out the gel that has been completely cooled in (3) and add calcium chloride solution as a crosslinking agent at room temperature. After the crosslinking is completed, rinse with ultrapure water to obtain a hydrogel with a double network structure.

[0076] In some embodiments, the concentration of calcium chloride is 1.5% to 2.5%, specifically 1.5%, 2%, 2.5%, or any concentration in between.

[0077] In some embodiments, the crosslinking time can be 15 min to 25 min. Specifically, it can be 15, 18, 21, or 25 min, or any number in between. If the crosslinking time is too short, the hydrogel will not crosslink completely; if the time is too long, the crosslinking will be excessive, resulting in overly dense pores, causing moisture loss and reduced flexibility.

[0078] (5) After (4) crosslinking is completed, rinse with ultrapure water to obtain a double network hydrogel.

[0079] A preferred preparation method is as follows: 2% gelatin is added to water and stirred at 50℃~60℃ to dissolve. After the gelatin is completely dissolved, 2% sodium alginate is added and stirred continuously at 50℃~60℃ to dissolve. 0.6% carrageenan and 0.3% xanthan gum are added to the sol and dissolved at 50℃~60℃. 0.2% potassium chloride is added and stirred continuously. Once the sol is completely dissolved, it is poured into a mold and refrigerated at 4℃ for 5 min~15 min. A 2% calcium chloride solution is then applied to the gel surface, and crosslinking is carried out for 15 min~25 min. After complete crosslinking, the gel is rinsed three times with ultrapure water to obtain a double-network hydrogel.

[0080] This invention, through the above preparation method, yields a dual-network structure hydrogel, a polymeric gel system formed by the interpenetration and synergistic effect of a rigid first network and a flexible second network. Its core advantages include significantly improved mechanical properties, structural stability, controllable swelling, and good biocompatibility. Furthermore, this hydrogel is composed of natural ingredients, contains no chemically synthesized components, and is less likely to cause allergic or irritating reactions. In cosmetics, this hydrogel can significantly improve skin feel, enhance moisturizing properties, active ingredient delivery, and product stability, and can be prepared in the form of eye masks, face masks, neck masks, hand masks, foot masks, etc.

[0081] Taking eye masks as an example, the preparation method is as follows: the prepared sol is poured into an eye mask mold, refrigerated and solidified, then cross-linked, and washed with ultrapure water to obtain a hydrogel eye mask with a double network structure.

[0082] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0083] The reagents used in the following examples were purchased from the following manufacturers:

[0084]

[0085] In Examples 1 to 7, Comparative Examples 1 to 11, and the Effect Examples of the present invention, the raw materials and reagents used can all be purchased from the market.

[0086] The present invention will be further illustrated below with reference to the embodiments:

[0087] Example 1

[0088] This embodiment describes a method for preparing a double-network structure hydrogel formed by the interpenetration of 2% sodium alginate and carrageenan, comprising the following steps:

[0089] (1) Add 1.2 g of gelatin to 56.94 g of water and stir at 50℃~60℃ to dissolve;

[0090] (2) After the gelatin is completely dissolved, add 1.2 g of sodium alginate and stir continuously;

[0091] (3) Add 0.36 g of carrageenan and stir until dissolved.

[0092] (4) After the above sol has been fully dissolved by stirring, stop stirring and add 0.18 g of xanthan gum at a high temperature of 50℃~60℃. After the xanthan gum has completely settled, start stirring.

[0093] (5) Add 0.12 g of potassium chloride and stir thoroughly to crosslink the carrageenan gel network;

[0094] (6) Pour the fully dissolved sol into a mold and place it in a 4°C refrigerator to cool and solidify for 5 min to 15 min;

[0095] (7) Add 2% calcium chloride to the mold and soak for 15 min to 25 min to crosslink sodium alginate to form a three-dimensional network structure. Wash with ultrapure water 3 times to remove excess calcium chloride solution and obtain a double network structure hydrogel.

[0096] Example 2

[0097] This embodiment describes a method for preparing a double-network structure hydrogel formed by the interpenetration of 1% sodium alginate and carrageenan, comprising the following steps:

[0098] (1) Add 1.2 g of gelatin to 57.54 g of water and stir at 50℃~60℃ to dissolve;

[0099] (2) After the gelatin is completely dissolved, add 0.6 g of sodium alginate and stir continuously;

[0100] (3) Add 0.36 g of carrageenan and stir until dissolved.

[0101] (4) After the above sol has been fully dissolved by stirring, stop stirring and add 0.18 g of xanthan gum at a high temperature of 50℃~60℃. After the xanthan gum has completely settled, start stirring.

[0102] (5) Add 0.12 g of potassium chloride and stir thoroughly to crosslink the carrageenan gel network;

[0103] (6) Pour the fully dissolved sol into a mold and place it in a 4°C refrigerator to cool and solidify for 5 min to 15 min;

[0104] (7) Add 2% calcium chloride to the mold and soak for 15 min to 25 min to crosslink sodium alginate to form a three-dimensional network structure. Wash with ultrapure water 3 times to remove excess calcium chloride solution and obtain a double network structure hydrogel.

[0105] Example 3

[0106] This embodiment describes a method for preparing a double-network structure hydrogel formed by the interpenetration of 3% sodium alginate and carrageenan, comprising the following steps:

[0107] (1) Add 1.2 g of gelatin to 56.34 g of water and stir at 50℃~60℃ to dissolve;

[0108] (2) After the gelatin is completely dissolved, add 1.8 g of sodium alginate and stir continuously;

[0109] (3) Add 0.36 g of carrageenan and stir until dissolved.

[0110] (4) After the above sol has been fully dissolved by stirring, stop stirring and add 0.18 g of xanthan gum at a high temperature of 50℃~60℃. After the xanthan gum has completely settled, start stirring.

[0111] (5) Add 0.12 g of potassium chloride and stir thoroughly to crosslink the carrageenan gel network;

[0112] (6) Pour the fully dissolved sol into a mold and place it in a 4°C refrigerator to cool and solidify for 5 min to 15 min;

[0113] (7) Add 2% calcium chloride to the mold and soak for 15 min to 25 min to crosslink sodium alginate to form a three-dimensional network structure. Wash with ultrapure water 3 times to remove excess calcium chloride solution and obtain a double network structure hydrogel.

[0114] Example 4

[0115] The only difference from Example 1 is that the solvent is replaced with Dendrobium officinale polysaccharide extract (Shikongxianzhu), while the other steps are the same as in Example 1. The resulting eye mask is uniform, soft, and conforms well to the skin, exhibiting excellent adhesion. A sample image is shown below. Figure 1 As shown.

[0116] Example 5

[0117] The only difference from Example 1 is that the solvent is replaced with *Auricularia auricula-judae* polysaccharide extract (*Auricularia auricula-judae*), while the other steps are the same as in Example 1. The resulting eye mask is uniform, soft, and conforms well to the skin, exhibiting excellent adhesion. A sample image is shown below. Figure 2 As shown.

[0118] Example 6

[0119] The only difference from Example 1 is that the solvent is replaced with brown rice and Job's tears extract (Yi Yan Yu Run); all other steps are the same as in Example 1. The eye mask obtained by this method is uniform, soft, and conforms well to the skin, exhibiting excellent adhesion. A sample image is shown below. Figure 3 As shown.

[0120] Example 7

[0121] Based on Example 1, 4% niacinamide, 0.5% glutathione, and 0.5% astaxanthin liposomes were added to achieve antioxidant, whitening, anti-aging, and skin-repairing effects. The resulting eye mask is uniform, soft, and adheres well to the skin, as shown in the image. Figure 4 As shown.

[0122] Comparative Example 1

[0123] This experiment describes a method for preparing a single-network hydrogel using 2% sodium alginate and gelatin as a matrix, including the following steps:

[0124] (1) Add 1.2 g of gelatin to 57.6 g of water and stir to dissolve at 50℃~60℃;

[0125] (2) After the gelatin is completely dissolved, add 1.2 g of sodium alginate and continue stirring to dissolve at a temperature of 50℃~60℃;

[0126] (3) After the sodium alginate is completely dissolved, pour the sol into the mold and refrigerate it for 5 min to 15 min.

[0127] (4) After refrigeration, 2% calcium chloride solution was completely covered on the surface of the sol. After crosslinking for 15 min to 25 min, the hydrogel was washed three times with ultrapure water to remove excess calcium chloride solution and obtain a single network structure hydrogel.

[0128] Comparative Example 2

[0129] This experiment describes a method for preparing a single-network hydrogel using 1% sodium alginate and gelatin as a matrix, including the following steps:

[0130] (1) Add 1.2 g of gelatin to 58.2 g of water and stir to dissolve at 50℃~60℃;

[0131] (2) After the gelatin is completely dissolved, add 0.6 g of sodium alginate and continue stirring to dissolve at a temperature of 50℃~60℃;

[0132] (3) After the sodium alginate is completely dissolved, pour the sol into the mold and refrigerate it for 5 min to 15 min.

[0133] (4) After refrigeration, 2% calcium chloride solution was completely covered on the surface of the sol. After crosslinking for 15 min to 25 min, the hydrogel was washed three times with ultrapure water to remove excess calcium chloride solution and obtain a single network structure hydrogel.

[0134] Comparative Example 3

[0135] This experiment describes a method for preparing a single-network hydrogel using 3% sodium alginate and gelatin as a matrix, including the following steps:

[0136] (1) Add 1.2 g of gelatin to 57 g of water and stir to dissolve at 50℃~60℃;

[0137] (2) After the gelatin is completely dissolved, add 1.8 g of sodium alginate and continue stirring to dissolve at 50℃~60℃.

[0138] (3) After the sodium alginate is completely dissolved, pour the sol into the mold and refrigerate it for 5 min to 15 min.

[0139] (4) After refrigeration, 2% calcium chloride solution was completely covered on the surface of the sol. After crosslinking for 15 min to 25 min, the hydrogel was washed three times with ultrapure water to remove excess calcium chloride solution and obtain a single network structure hydrogel.

[0140] Comparative Example 4

[0141] This experiment demonstrates a method for preparing a single-network structure hydrogel based on carrageenan, comprising the following steps:

[0142] (1) Add 0.18 g xanthan gum to 59.34 g water, and after it swells completely, stir to dissolve at a temperature of 50℃~60℃;

[0143] (2) Add 0.36 g of carrageenan and stir continuously at 50℃~60℃ to dissolve;

[0144] (3) After a uniform sol is formed, add 0.12 g of potassium chloride and stir continuously at 50℃~60℃ to dissolve it;

[0145] (4) While the sol is still hot, pour it into the mold and refrigerate it for 5 min to 15 min to obtain a single network structure hydrogel with carrageenan as the matrix.

[0146] Comparative Example 5

[0147] The only difference from Example 1 is that the amount of gelatin added is 0.5%, while the other steps are the same as in Example 1. The sol obtained by this method has a low viscosity, only 259 mPa·s.

[0148] Comparative Example 6

[0149] The only difference from Example 1 is that the amount of gelatin added is 8%, while the other steps are the same as in Example 1. The sol viscosity obtained by this method is too high, at 2026 mPa·s, which will affect the uniformity of the eye mask formation.

[0150] Comparative Example 7

[0151] The only difference from Example 1 is that the amount of xanthan gum added is 0.15%, while the other steps are the same as in Example 1. The sol obtained by this method has a low viscosity, only 382 mPa·s.

[0152] Comparative Example 8

[0153] The only difference from Example 1 is that the amount of xanthan gum added is 1.2%, while the other steps are the same as in Example 1. The sol viscosity obtained by this method is too high, at 4008 mPa·s, which will affect the uniformity of the eye mask formation.

[0154] Comparative Example 9

[0155] The only difference from Example 1 is that the low-viscosity sodium alginate is replaced with high-viscosity sodium alginate from Maclean's. Too high a viscosity sodium alginate will cause excessive cross-linking, resulting in a dense network structure, and the colloid will shrink due to water loss. (See the attached image.) Figure 5 As shown.

[0156] Comparative Example 10

[0157] The only difference from Example 1 is that xanthan gum is replaced with 0.6% konjac glucomannan, and water is used to bring the content to 100%. All other steps are the same as in Example 1. The hydrogel prepared by this method exhibits severe clumping, an uneven surface, high viscosity, and a tendency to form air bubbles. A picture of the actual product is shown below. Figure 6 As shown.

[0158] Comparative Example 11

[0159] The only difference from Example 1 is that xanthan gum is replaced with 0.3% gellan gum; all other steps are the same as in Example 1. The hydrogel prepared by this method has poor mechanical properties and is easily broken. A physical image is shown below. Figure 7 As shown.

[0160] Example of effect

[0161] 1. The determination of the water retention properties of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1 includes the following steps:

[0162] (1) Determination of water content of the double-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0163] Three pieces of the prepared hydrogel were weighed, frozen overnight at -80℃, and then freeze-dried for 48 hours. Afterward, they were weighed again, and the water content of the hydrogels was calculated and averaged. The water content of the hydrogels was calculated using the following formula:

[0164] ;

[0165] The water content of the dual-network structure hydrogel was 92.0%, and the water content of the single-network structure hydrogel was 94.3%. Both hydrogels have a water content of over 90%, which is much higher than that of other hydrogel skincare products on the market, giving them a significant advantage in hydration and moisturizing.

[0166] (2) Short-term water retention determination of the double-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0167] Three hydrogel samples were weighed and then exposed to air at room temperature. They were weighed every 10 minutes for 2 hours. The water retention rate of the hydrogels was calculated using the following formula:

[0168] ;

[0169] like Figure 8 As shown, the water retention rate of the dual-network hydrogel after being exposed to air at room temperature for 2 hours was 93.83%, while that of the single-network hydrogel after being exposed to air at room temperature for 2 hours was 83.35%. This indicates that the dual-network hydrogel significantly improves its water retention capacity through its interpenetrating network structure.

[0170] (3) Long-term water loss determination of the double-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0171] Three hydrogel samples were weighed and then exposed to air at room temperature. They were weighed every hour on the first day, and then weighed and photographed every 1, 3, 7, 14, and 28 days thereafter. The experiment lasted a total of 28 days. The water loss rate of the hydrogels was calculated using the following formula:

[0172] ;

[0173] like Figure 9As shown, after being exposed to air at room temperature for one day, the water loss rate of the dual-network hydrogel was consistently much lower than that of the single-network hydrogel. The water loss rate of the single-network hydrogel was 51.81%, while that of the dual-network hydrogel was only 37.08%, indicating that the dual network has a stronger ability to bind free water. In the middle stage (3-7 days), the water loss rate gradually decreased, entering a slow release phase of bound water. The rate difference between the dual and single networks narrowed, but the water retention advantage of the dual network remained. In the later stage (7-28 days), almost all the water was lost.

[0174] 2. The skin moisturizing properties of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1 were determined, including the following steps:

[0175] The method for determining the skin moisture content after applying the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1 to the skin is as follows:

[0176] Three volunteers were selected. Their forearms were washed, and the skin hydration level was measured. Four patches of double-network hydrogel were applied to the left forearm of each volunteer, and four patches of single-network hydrogel were applied to the right forearm. After 15 minutes, one hydrogel was removed to measure the hydration level of the skin covered by the hydrogel. After 30 minutes, another hydrogel was removed to measure the hydration level of the skin covered by the hydrogel. After 45 minutes, another hydrogel was removed to measure the hydration level of the skin covered by the hydrogel. After 60 minutes, another hydrogel was removed to measure the hydration level of the skin covered by the hydrogel. The average data from the three volunteers was plotted.

[0177] Depend on Figure 10 The results showed that when the dual-network structure hydrogel was applied to the skin for 15 minutes, the skin water content increased significantly, indicating that it has excellent skin moisturizing properties.

[0178] 3. The swelling properties of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1 are determined by the following steps:

[0179] (1) Lyophilization treatment of the double-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0180] Three pieces of the prepared dual-network structure hydrogel and single-network structure hydrogel were taken and frozen overnight in a -80℃ freezer. After the hydrogels were completely frozen, they were placed in a freeze dryer for freeze drying. After freeze drying for 48 hours, they were taken out and weighed.

[0181] (2) Swelling properties of the double-network hydrogel obtained in Example 1 and the single-network hydrogel obtained in Comparative Example 1:

[0182] The freeze-dried hydrogels were placed in ultrapure water and weighed periodically. The experiment lasted for 24 hours, and the average data from three hydrogel samples were plotted. The swelling ratio was calculated using the following formula:

[0183] ;

[0184] Figure 11 The experimental results show that the equilibrium swelling rate of the dual-network hydrogel is 517.2%, which is significantly lower than that of the single-network hydrogel (1181.2%). This is because the dual-network structure can effectively limit the swelling of the hydrogel, ensuring sufficient water absorption capacity while preventing excessive swelling and deformation.

[0185] 4. SEM morphology comparison of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1, including the following steps:

[0186] Samples for SEM observation were prepared using a freeze-drying method to maintain the three-dimensional network structure of the hydrogel.

[0187] (1) Place the fully swollen and balanced hydrogel sample at -80℃ for rapid freezing overnight to allow the water inside the sample to form fine ice crystals. Quickly transfer the frozen sample to a vacuum freeze dryer and dry it at -50℃ and 0.1 mbar for 48 hours to allow the ice crystals to sublimate directly;

[0188] (2) Use a blade to fracture the sample in liquid nitrogen to obtain a fresh fracture surface;

[0189] (3) After drying, the sample is pasted onto conductive tape with the cross-section facing up. A gold layer is then deposited using an ion sputtering instrument to enhance the conductivity of the sample. The sample is then photographed.

[0190] Depend on Figure 12 It can be seen that, compared with single-network hydrogels, dual-network hydrogels have a denser three-dimensional network structure, which provides the hydrogel with better mechanical support and water binding ability.

[0191] 5. A comparison of the mechanical properties of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1, including the following steps:

[0192] (1) Comparison of tensile properties of the double-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0193] Double-network and single-network hydrogels were prepared according to Example 1 and Comparative Example 1, respectively, and tested using an electronic universal testing machine. Figure 13As can be seen, the fracture load of the dual-network hydrogel is 0.4 N, and the elongation at break is 45.46%. In contrast, the fracture load of the single-network structure is 0.19 N, and the elongation at break is 17.2%. This fully demonstrates that the dual-network hydrogel is superior to the single-network hydrogel in terms of tensile mechanical properties, possessing high toughness, tear resistance, and deformation resistance.

[0194] (2) Comparison of compressibility test between the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1:

[0195] Double-network and single-network hydrogels were prepared according to Example 1 and Comparative Example 1, respectively, and tested using an electronic universal testing machine. Figure 14 As can be seen, the maximum load of the single-network structure hydrogel is 147.89 N. The maximum load of the double-network structure hydrogel is 151.95 N, and the overall curve performance is also better, exhibiting high compressive strength, high compressive toughness, and resistance to compression cracking.

[0196] 6. A comparison of the rheological properties of the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1, including the following steps:

[0197] Samples were prepared according to Example 1 and Comparative Example 1, and tested using a rheometer. Figure 15 As the angular frequency increases, the loss modulus G'' of the single-network hydrogel exceeds the storage modulus G', and the gel network structure begins to collapse. In contrast, the storage modulus of the double-network hydrogel exceeds the loss modulus, indicating that it possesses superior mechanical properties and can maintain its elastic gel structure.

[0198] 7. A comparison of the release rates of the active ingredient by the dual-network structure hydrogel obtained in Example 1 and the single-network structure hydrogel obtained in Comparative Example 1, including the following steps:

[0199] Nicotinamide was selected as an example of an active ingredient.

[0200] Plotting the standard curve:

[0201] Accurately weigh 20 mg of nicotinamide standard into a 10 mL volumetric flask. Dissolve in 0.01 M hydrochloric acid solution and dilute to the mark to obtain a 2 mg / mL stock solution. Precisely draw up the stock solution. Transfer 1.0 mL to a 10 mL volumetric flask, dilute to volume with PBS, and obtain a stock solution of 200 μg / mL. From the stock solution Accurately pipette different volumes and dilute them with PBS into 10 mL volumetric flasks to prepare the following concentration series: 5, 10, 20, 40, 60, 80, 100 μg / mL.

[0202] Using PBS as a blank control, the absorbance of solutions at each concentration was measured at 261 nm, with each concentration measured in triplicate. A linear regression was performed with nicotinamide concentration (x, μg / mL) on the x-axis and absorbance (y) on the y-axis to obtain the standard curve equation:

[0203] ;

[0204] (2) Determination of nicotinamide release from hydrogels:

[0205] Double-network hydrogels (Example 1) and single-network hydrogels (Comparative Example 1) of the same size were prepared, with three replicates for each sample. Hydrogel sheets were immersed in nicotinamide solution (10 mg / mL) and loaded at 4°C for 24 h. After removal, the surface moisture was blotted dry with filter paper, and the loading was measured. The average loading of the double-network hydrogel was 5.82 mg / sheet, and the average loading of the single-network hydrogel was 5.73 mg / sheet. Hydrogels were immersed in PBS solution and placed in a shaker at 32°C and 300 rpm. 2 mL samples were taken every 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 hours, with an equal volume and temperature of fresh PBS added immediately after each sampling. The sample solution was filtered through a 0.45 μm filter membrane, and the absorbance at 261 nm was measured. The cumulative release rate at each time point was calculated using the following formula:

[0206] ;

[0207] Among them: Q n : Cumulative release rate (%) at the nth time point; C n : Concentration measured in the nth sample (μg / mL); V0: Total volume of PBS solution in the tube (7 mL); V: Volume of each sample (2 mL); W0: Initial loading of nicotinamide in the hydrogel (μg).

[0208] Depend on Figure 16As can be seen, throughout the entire nicotinamide release cycle, the cumulative release rate of the dual-network hydrogel was consistently higher than that of the single-network hydrogel at any given time, and the difference continued to widen over time. At 0.5 h, the dual-network hydrogel released 8.28%, while the single-network hydrogel released 3.54%; at 24 h, the dual-network hydrogel released a cumulative 92.7% of nicotinamide, while the single-network hydrogel released only 71.2%. This is because the interpenetrating framework of the dual networks can form a stable and interconnected multi-level porous structure. During water absorption and swelling, the two networks support each other, preventing pore collapse and channel blockage. This indicates that the dual-network hydrogel can effectively load and release active ingredients, making it a suitable carrier for ocular membranes.

[0209] 8. The hemolysis experiment of the dual-network structure hydrogel obtained in Example 1 includes the following steps:

[0210] First, 1 mL of rabbit blood was centrifuged, the supernatant and middle layer were discarded, and the lower layer of blood cell pellet was taken and mixed with physiological saline to prepare a 2% erythrocyte solution. 1 mL of 2% erythrocyte solution was mixed with 20 μL of physiological saline as a negative control group, and 1 mL of 2% erythrocyte solution was mixed with 20 μL of SDS as a positive control group. 1.02 mL of 2% erythrocytes was added to a hydrogel centrifuge tube containing 1 g of the solution from Example 1 as the experimental group. Three groups were prepared for each of the experimental group, negative control group, and positive control group. After mixing and standing for 3 h, the supernatant was taken after centrifugation and the absorbance at 541 nm was measured.

[0211] according to Figure 17 The experimental results show that the hemolysis rate of the hydrogel is 0.16%, which is much less than 5%, indicating good blood compatibility.

[0212] 9. The calculation of the synergistic effect of the dual-network structure hydrogel obtained in Example 1 includes the following steps:

[0213] The calcium-crosslinked sodium alginate + gelatin from Comparative Example 1 was designated as Group A1; the potassium-crosslinked carrageenan + xanthan gum from Comparative Example 4 was designated as Group B; and Example 1 was a combination of Group A1 and Group B. The water retention rate of these groups after 24 hours of exposure to air was tested. The water retention rate was calculated according to the formula in Example 1, and the synergistic index of the water retention rate was calculated according to the following formula:

[0214] ;

[0215] Among them, E A E represents the average water retention rate of group A. B E represents the average water retention rate of group B. AB The average water retention rate of Group A and Group B is the combined average of Example 1. SI > 1 indicates a synergistic effect; SI = 1 indicates an additive effect; SI < 1 indicates an antagonistic effect.

[0216] ;

[0217] The water retention rate of the dual-network hydrogel prepared by combining group A1 and group B (Example 1) was 71.11%, which was higher than the expected value of the sum of group A1 (37.44%) and group B (25.82%) (63.25%). The synergy coefficient SI = 1.12, indicating that there is a significant synergistic enhancement effect between the two network components.

[0218] 10. The calculation of the synergistic effect of water retention of the dual-network structure hydrogel obtained in Example 2 includes the following steps:

[0219] The calcium-crosslinked sodium alginate and gelatin from Comparative Example 2 were designated as Group A2; the potassium-crosslinked carrageenan and xanthan gum from Comparative Example 4 were designated as Group B; and Example 2 was a combination of Group A2 and Group B. The water retention rate of these groups after 24 hours of exposure to air was tested. The water retention rate was calculated according to the formula in Experimental Example 1, and the synergistic index of the water retention rate was calculated according to the formula in Experimental Example 9.

[0220] The water retention rate of the dual-network hydrogel prepared by combining group A2 and group B (Example 2) was 69.18%, which was higher than the expected value of the sum of group A2 (36.92%) and group B (25.82%) (62.73%). The synergy coefficient SI = 1.10, indicating that there is a significant synergistic enhancement effect between the two network components.

[0221] 11. The calculation of the synergistic effect of water retention of the dual-network structure hydrogel obtained in Example 3 includes the following steps:

[0222] The calcium-crosslinked sodium alginate and gelatin from Comparative Example 3 were designated as Group A3; the potassium-crosslinked carrageenan and xanthan gum from Comparative Example 4 were designated as Group B; and Example 3 was a combination of Group A3 and Group B. The water retention rate of these groups after 24 hours of exposure to air was tested. The water retention rate was calculated according to the formula in Experimental Example 1, and the synergistic index of the water retention rate was calculated according to the formula in Experimental Example 9.

[0223] The water retention rate of the dual-network hydrogel prepared by combining group A3 and group B (Example 3) was 72.90%, which was higher than the expected value of the sum of group A3 (39.78%) and group B (25.82%) (65.60%). The synergy coefficient SI = 1.11, indicating that there is a significant synergistic enhancement effect between the two network components.

[0224] The above results demonstrate that, compared with single-network hydrogel, the dual-network hydrogel eye mask prepared by the present invention with a specific ratio has significantly improved mechanical strength and toughness, is less prone to breakage, adheres better and is less likely to deform or fall off, while also having longer-lasting water retention and a more uniform pore structure, enabling stable loading and gentle slow release of active ingredients, and having stronger structural stability, making it less prone to swelling and disintegration during use, thus meeting the care needs of the delicate skin around the eyes.

[0225] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-network hydrogel, characterized in that, include: First network and second network; The first network comprises a first anionic polymer crosslinked with a first metal ion, and the second network comprises a second anionic polymer crosslinked with a second metal ion; The first anionic polymer and the second anionic polymer are independently selected from: sodium alginate and carrageenan; The first metal ion and the second metal ion are independently selected from calcium ions and potassium ions; The first anionic polymer and the second anionic polymer may be the same or different; The first metal ion and the second metal ion can be the same or different.

2. The dual-network hydrogel as described in claim 1, characterized in that, Also includes: Modified components; The modified components include gelatin and / or xanthan gum.

3. The dual-network hydrogel as described in claim 2, characterized in that, The first network contains: calcium ion crosslinked sodium alginate and gelatin; the second network contains: potassium ion crosslinked carrageenan and xanthan gum; the mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum is (10~30):(10~40):(4~8):(2~5).

4. The method for preparing the dual-network hydrogel as described in claim 3, characterized in that, The gelatin, sodium alginate, carrageenan and xanthan gum were dissolved in a solvent in sequence, and the mixture was pre-crosslinked, solidified, crosslinked again and washed with water to obtain the hydrogel. The pre-crosslinking uses potassium ions; the secondary crosslinking uses calcium ions.

5. The preparation method according to claim 4, characterized in that, The mass ratio of sodium alginate, gelatin, carrageenan and xanthan gum is (10~30): (10~40): (4~8): (2~5).

6. The preparation method according to claim 4 or 5, characterized in that, The solvent includes: water and / or plant polysaccharide extract.

7. The use of the dual-network hydrogel according to any one of claims 1 to 3 and / or the dual-network hydrogel obtained by the preparation method according to any one of claims 4 to 6 in the preparation of topical skin dressings.

8. The application as described in claim 7, characterized in that, The topical skin patch has one or more of the following effects: anti-oxidation, whitening, anti-aging, and repair.

9. The application as described in claim 7 or 8, characterized in that, The topical skin dressings include one or more of the following: face masks, eye masks, neck masks, lip masks, nose masks, and local skin care dressings.

10. A topical skin dressing, characterized in that, include: The dual-network hydrogel as described in any one of claims 1 to 3 and / or the dual-network hydrogel obtained by the preparation method as described in any one of claims 4 to 6, as well as cosmetic-acceptable adjuvants.

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