Composite crosslinked three-dimensional cellulose gel material, preparation method and application thereof

Abstract

The application discloses a kind of composite crosslinking three-dimensional cellulose gel materials and its preparation method and application, and the raw material of preparation gel material includes CMC-Na, PEG6000, malic acid, PVP K30, lactic acid, citric acid.Preparation method includes raw material pretreatment, add PEG and homogenization, malic acid first crosslinking, add PVP and homogenization, add lactic acid solution and mix, citric acid second crosslinking, pH adjustment, gradient ethanol washing, vacuum drying, crushing screening step.The application adopts multiple crosslinking technology, PEG participates in crosslinking, malic acid first crosslinking, citric acid second crosslinking, forms stable three-dimensional network structure, gives material excellent anti-glycation activity and antioxidant activity, AGEs inhibition rate reaches 85.6%, DPPH clearance rate reaches 78.5%.Preparation method condition is mild, process is simple, easy to industrial production.The obtained product can be widely used in anti-aging product.

Description

Technical Field

[0001] This application belongs to the field of functional cosmetic raw material technology, specifically relating to a composite cross-linked three-dimensional cellulose gel material, its preparation method, and its application in anti-glycation skin care products and antioxidant skin care products. Background Technology

[0002] With rising living standards and increased health awareness, the cosmetics industry has experienced rapid growth. Consumers are increasingly demanding higher standards for the safety, efficacy, and natural properties of cosmetics, leading to a significant increase in market demand for functional ingredients. Glycation refers to the nucleophilic addition reaction between proteins and the free carbonyl groups of reducing sugars, generating unstable Schiff bases. These Schiff bases then rearrange to form Amadori rearrangement products, and under a series of irreversible reactions such as oxidative stress and dehydration, they ultimately cross-link to form advanced glycation end products (AGEs). The accumulation of AGEs in the dermis leads to abnormal covalent cross-linking between collagen fibers, resulting in decreased skin elasticity, increased wrinkles, and a dull complexion due to pigment deposition. Therefore, inhibiting glycation has become a key focus in anti-aging skincare.

[0003] Existing anti-glycation raw materials mainly include chemically synthesized carbonyl-scavenging substances such as aminoguanidine, carnosine, and pyridoxine, as well as some plant extracts. Chemically synthesized raw materials competitively bind dicarbonyl intermediates with highly reactive amino groups, but face serious problems such as cytotoxicity and safety controversies. Plant extracts mainly rely on antioxidant pathways to indirectly inhibit the glycation process, but in cosmetic formulations, they often face industrial application challenges such as poor stability to light and heat, easy discoloration, high extraction costs, and large batch-to-batch activity fluctuations. Existing hydrogel materials mostly use a single crosslinking agent or simple physical mixing methods. The gel structure prepared by this conventional method is unstable and often requires temperatures exceeding 100 degrees Celsius to induce acid dehydration and form more reactive anhydride intermediates for chemical reactions, easily leading to thermal degradation and yellowing of macromolecular raw materials.

[0004] Sodium carboxymethyl cellulose (CMC) is a naturally derived, water-soluble polymer with good biocompatibility and safety. Free CMC macromolecules can inhibit the formation of some advanced glycation end products (AGEs) at specific concentrations. However, ordinary free CMC materials, lacking a specific three-dimensional physical structure, have limited anti-glycation activity and cannot effectively intercept small-molecule glycation intermediates in a liquid environment, thus failing to meet the needs of high-end skincare products. Therefore, developing a composite cross-linked gel material that can be prepared under mild conditions, possesses high anti-glycation activity, and has a stable structure is of significant value. Summary of the Invention

[0005] The first aspect of this application provides a composite cross-linked three-dimensional cellulose gel material. The gel material has a three-dimensional cross-linked gel network with sodium carboxymethyl cellulose as the main chain. Polyethylene glycol macromolecules and polyvinylpyrrolidone macromolecules are interwoven and physically bonded within the main chain. The main chain is sequentially subjected to malic acid through dicarboxyl dehydration esterification to form a primary linear cross-linked structure, and then subjected to citric acid through a ring-opening reaction to form an anhydride intermediate to construct a ternary carboxyl branched secondary cross-linked structure, thereby locking the polyethylene glycol macromolecules and polyvinylpyrrolidone macromolecules within the gel network. Lactic acid molecules for competitively capturing dicarbonyl compounds are bonded to the internal micropores of the gel network through hydrogen bonds or polar interactions. The gel material has an inhibition rate of not less than 80% for advanced glycation end products and a scavenging rate of not less than 75% for DPPH free radicals.

[0006] In some embodiments, the raw materials for preparing the gel material include, by weight, 2-5 parts sodium carboxymethyl cellulose, 0.3-1 parts polyethylene glycol, 0.5-2 parts malic acid, 0.5-2 parts polyvinylpyrrolidone, 0.3-1.5 parts lactic acid, and 0.5-2 parts citric acid.

[0007] In some embodiments, the water content of the gel material is less than 10%, and the particle size is 80-200 mesh.

[0008] In some embodiments, the gel material exhibits an inhibition rate of 83.8%-87.2% against advanced glycation end products (AGEs), a scavenging rate of 76.2%-80.5% against DPPH radicals, and a scavenging rate of 80.5%-84.1% against ABTS radicals.

[0009] A second aspect of this application provides a method for preparing a composite cross-linked three-dimensional cellulose gel material according to the first aspect of this application, comprising the following steps: Step 1: Dissolve sodium carboxymethyl cellulose in deionized water and allow it to swell at 40-60℃ for 1-3 hours to obtain a sodium carboxymethyl cellulose solution; Step 2: Add polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 40-60℃ for 10-30 minutes; Step 3: Add malic acid to the reaction system obtained in Step 2, adjust the pH to 3.0-4.5, and react at 50-70℃ for 1-3 hours to form a preliminary cross-linked gel network; Step 4: Add polyvinylpyrrolidone to the reaction system obtained in Step 3, and homogenize at 40-55℃ for 10-20 minutes to ensure that polyvinylpyrrolidone is uniformly dispersed in the gel network. Step 5: Add lactic acid to the reaction system obtained in Step 4, and stir and mix at 40-55℃ for 20-40 minutes to ensure that the lactic acid is evenly dispersed and combines with the gel network; Step 6: Add citric acid to the reaction system obtained in Step 5 and react at 50-70℃ for 1-2 hours to stabilize and strengthen the gel network; Step 7: Adjust the pH of the system to 5.5-6.5; Step 8: Wash, dry, pulverize, and sieve the reaction product to obtain the composite cross-linked three-dimensional cellulose gel material.

[0010] In some embodiments, washing the reaction product includes: first washing 2-3 times with a 50% ethanol solution at a solid-liquid ratio of 1:4, and then washing 2-3 times with a 90% ethanol solution at a solid-liquid ratio of 1:3.

[0011] In some embodiments, the ethanol washing process is carried out in conjunction with a stirring and vibration system, wherein the stirring speed is 10-30 rpm, and the stirring method is adopted, with a cycle of stirring for 5 minutes and letting stand for 2 minutes; the vibration frequency is 20-50 Hz, the amplitude is 1-3 mm, and the vibration method is adopted, with a cycle of vibrating for 3 minutes and letting stand for 2 minutes.

[0012] In some embodiments, the drying in step eight is vacuum drying, and the temperature of vacuum drying is 50-60°C.

[0013] In some embodiments, the sieving in step eight is sieving through an 80-200 mesh sieve.

[0014] The third aspect of this application provides the use of a composite cross-linked three-dimensional cellulose gel material as described in the first aspect of this application, or a composite cross-linked three-dimensional cellulose gel material prepared by the method of the second aspect of this application, in the preparation of anti-glycation skin care products or antioxidant skin care products. Attached Figure Description

[0015] Figure 1 The chemical structural formula of the composite cross-linked three-dimensional cellulose gel material in this application embodiment is shown below.

[0016] Figure 2 This is a schematic diagram of the molecular structure of the composite cross-linked three-dimensional cellulose gel material according to an embodiment of this application.

[0017] Figure 3 This is a photograph of the composite cross-linked three-dimensional cellulose gel material before swelling, according to an embodiment of this application.

[0018] Figure 4 This is a photograph of the composite cross-linked three-dimensional cellulose gel material before swelling, according to an embodiment of this application.

[0019] Figure 5 This is a schematic flowchart illustrating the preparation method of the composite cross-linked three-dimensional cellulose gel material according to an embodiment of this application. Detailed Implementation

[0020] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0021] This application provides a composite cross-linked three-dimensional cellulose gel material 100. The gel material 100 has a three-dimensional cross-linked gel network with sodium carboxymethyl cellulose as the main chain. Polyethylene glycol macromolecules and polyvinylpyrrolidone macromolecules are interwoven and physically bonded within the main chain. The main chain is sequentially dehydrated and esterified by malic acid through a dicarboxyl group to form a primary linear cross-linked structure, and then constructed by a ring-opening reaction with citric acid through the formation of an anhydride intermediate to construct a ternary carboxyl group branched secondary cross-linked structure, thereby locking the polyethylene glycol macromolecules and polyvinylpyrrolidone macromolecules within the gel network. Lactic acid molecules for competitively capturing dicarbonyl compounds are bonded to the internal micropores of the gel network through hydrogen bonds or polar interactions. The gel material 100 has an inhibition rate of not less than 80% for advanced glycation end products and a scavenging rate of not less than 75% for DPPH free radicals.

[0022] The molecular formula of the gel material 100 in this embodiment is: CMC O CO R CO O CMC. Its chemical structural formula and molecular structure diagram are as follows: Figure 1 and Figure 2 As shown. A physical image of the gel material 100 according to an embodiment of this application is shown below. Figure 3 and Figure 4 As shown. Among them. Figure 3 This is the state before swelling. Figure 4 This is the state after swelling.

[0023] Sodium carboxymethyl cellulose (CMC) is a naturally derived anionic cellulose ether derivative obtained by carboxymethylation modification of natural cellulose. Its molecular chain consists of β-D-glucose units linked by 1,4-glycosidic bonds, with the hydroxyl groups on each glucose unit replaced by carboxymethyl groups. The molecular chain backbone of CMC is relatively rigid and rich in hydroxyl and carboxymethyl groups. These hydrophilic groups provide the basic swelling force through electrostatic repulsion and hydrogen-bonded hydration. Simultaneously, the free hydroxyl groups on the molecular chain are the core binding sites for subsequent esterification and crosslinking reactions. In the embodiments of this application, CMC serves as the main chain backbone of a three-dimensional network, undertaking the structural function of supporting the entire gel structure and providing reaction sites for crosslinking reactions and the binding of functional molecules.

[0024] Polyethylene glycol (PEG) is a nonionic linear polyether with high chain flexibility, containing numerous ether-oxygen bonds in its molecular chain. For example, a medium molecular weight PEG6000 can be selected. The molecular weight of PEG6000 allows its molecular chains to interpenetrate multiple times between CMC molecular chains, forming numerous physical entanglement points. This physical crosslinking, synergistically with subsequent chemical crosslinking, constructs a more stable and flexible three-dimensional network; the PEG chain is key to forming the interpenetrating and entangled network structure. Simultaneously, PEG6000 dissolves well at reaction temperatures of 40-60°C while maintaining its molecular chain flexibility, facilitating uniform dispersion during homogenization. Excessively high molecular weight leads to excessively high solution viscosity, affecting the efficiency of subsequent crosslinking reactions. The physical crosslinking points formed by PEG6000 in the gel network can act as site-occupying points after material drying, contributing to the formation of microporous structures conducive to the loading and exchange of active ingredients (such as lactic acid).

[0025] Polyvinylpyrrolidone is a nonionic synthetic polymer containing a strongly polar lactam ring, whose lactam structure has strong polarity and hydrogen bond acceptance.

[0026] In the preparation of the gel material, polyethylene glycol (PEG) is added after sodium carboxymethyl cellulose (CCMC) has swollen, and binds to the CCMC molecular chains through hydrogen bonding. The long chains of PEG interweave between the rigid backbone of CCMC, increasing the free volume of the system, lowering the glass transition temperature, imparting flexibility to the hydrogel, and preventing dry-state cracking. The lactam structure of polyvinylpyrrolidone (PVP) can generate dipole-dipole interactions and physical entanglement with the CCMC network. Its uniform dispersion improves the density of the gel and enhances the smoothness and film adhesion of the final material on the skin surface. For example, PVP K30 is used as the PVP.

[0027] From a polymer thermodynamics perspective, under homogeneous shear force, polyethylene glycol and polyvinylpyrrolidone overcome the common phase separation tendency in polymer blends, forming a thermodynamically metastable homogeneous mixture. Although no chemical bonding occurs at this stage, a relatively elastic physical hydrogel network is formed through high-density hydrogen bonds, providing a spatial template for subsequent hierarchical chemical crosslinking.

[0028] The presence of polyethylene glycol and polyvinylpyrrolidone solves the technical problems of poor flexibility and insufficient film-forming properties in traditional sodium carboxymethyl cellulose gel. Through physical interpenetration and hydrogen bonding, the two significantly improve the mechanical properties and skin feel of the material without affecting subsequent chemical crosslinking.

[0029] Malic acid is a dicarboxylic acid containing two carboxyl groups and one hydroxyl group in its molecule. Under slightly acidic catalytic conditions, the free carboxyl groups at both ends of malic acid undergo a dehydration esterification reaction with the primary alcohol hydroxyl groups on the two adjacent sodium carboxymethyl cellulose molecular chains, forming intermolecular crosslinks. Its chemical bonding mode can be represented as: sodium carboxymethyl cellulose - oxygen - carbonyl - carbon chain - carbonyl - oxygen - sodium carboxymethyl cellulose.

[0030] Because malic acid molecules are relatively short and possess only two reactive end groups, they act as linear bridges at the molecular level. This crosslinking method initially connects the free sodium carboxymethyl cellulose molecules, forming a primary three-dimensional network framework with a large free volume and porous characteristics. At this stage, the crosslinking density is low, and the entire network maintains a high degree of swelling freedom. This relatively loose primary topology provides the necessary physical space for the subsequent deep penetration and uniform distribution of polyethylene glycol, polyvinylpyrrolidone, and lactic acid, avoiding internal spatial repulsion caused by premature network densification.

[0031] Malic acid crosslinking solves the problem of single crosslinking agents being unable to form a gradient crosslinking density. By first constructing a loose primary network, space is reserved for the interpenetration of functional macromolecules, which is a key prerequisite for achieving synergistic effects among multiple components.

[0032] Citric acid is a tricarboxylic acid containing three carboxyl groups and one hydroxyl group in its molecule. Under heating and slightly acidic conditions, adjacent carboxyl groups within the citric acid molecule first undergo intramolecular dehydration to form a highly reactive cyclic intermediate, citric anhydride. This cyclic anhydride has strong electrophilic properties and can rapidly attack the unreacted hydroxyl groups on the sodium carboxymethyl cellulose backbone, initiating a ring-opening esterification reaction.

[0033] Because citric acid possesses three functional groups capable of participating in reactions, it can act not only as a linear crosslinking agent but also as a branching crosslinking center in the system, simultaneously connecting three or more polymer chains. Based on the primary linear framework constructed by malic acid, the intervention of citric acid triggers numerous secondary esterification reactions, locking the microstructure. This two-step crosslinking mechanism, first linear and then branched, locks polyethylene glycol and polyvinylpyrrolidone, which were originally free or only physically bound, within a dense network through steric hindrance and the synergistic effect of chemical bonds.

[0034] Citric acid secondary crosslinking solves the technical problems of insufficient mechanical strength and loose structure of the primary network. By forming branched crosslinking centers, the crosslinking density and structural stability of the gel are greatly improved, while the interwoven functional macromolecules are permanently fixed inside the network.

[0035] Lactic acid is a short-chain α-hydroxy acid containing hydroxy and carboxyl groups. Lactic acid can be added under heating conditions and stirred to ensure uniform dispersion and binding with the gel network. The carboxyl groups of the lactic acid molecule interact polarly or form hydrogen bonds with the sodium carboxymethyl cellulose molecular chains, while its hydroxyl ends extend into the network channels.

[0036] The mechanism of lactic acid's anti-glycation effect is as follows. The key toxic intermediates in glycation are dicarbonyl compounds, including methylglyoxal and glyoxal. These dicarbonyl compounds are far more reactive than glucose; they react rapidly with large protein molecules, irreversibly forming advanced glycation end products (AGEs). The hydroxyl groups in lactic acid molecules can undergo nucleophilic addition reactions with dicarbonyl compounds in a slightly acidic environment, consuming these toxic intermediates and thus blocking their binding to skin structural proteins such as collagen and elastin.

[0037] In the three-dimensional network structure of this application, lactic acid is bound within the micropores of the gel network, significantly amplifying its effects. First, the network structure slows down the evaporation of bound water, creating localized high-concentration regions of lactic acid retained in the micropores. Second, the dicarbonyl compound, with its small molecular weight, can rapidly diffuse into the mesoporous structure of the gel through a concentration gradient. Third, within the confined space of the three-dimensional micropores, the local collision frequency between the dicarbonyl compound and lactic acid molecules is significantly increased, accelerating the reaction rate. Finally, the hydroxyl groups of lactic acid, combined with the slightly acidic environment, react with the dicarbonyl compound, consuming and neutralizing it, thus blocking the evolution of Schiff bases into irreversible late-stage glycosylation end products at the source.

[0038] The binding of lactic acid molecules resolves the technical issues of safety controversies and poor stability of existing anti-glycation raw materials. Lactic acid itself is an endogenous substance with good biocompatibility. By anchoring lactic acid within a three-dimensional network, the potential irritation caused by free lactic acid in the formulation is avoided, while simultaneously achieving the continuous release and amplification of the anti-glycation activity of lactic acid.

[0039] Through the synergistic effect of the above-mentioned structures, the composite cross-linked three-dimensional cellulose gel material provided in this application achieves quantifiable superior performance. The inhibition rate of advanced glycation end products (AGEs) is no less than 80%, specifically reaching 83.8% to 87.2%. The scavenging rate of DPPH (1,1-Diphenyl-2-picrylhydrazyl, 1,1-diphenyl-2-trinitrophenylhydrazine) radicals is no less than 75%, specifically reaching 76.2% to 80.5%. These performance parameters are the result of the synergistic effect of the above-mentioned multi-level structural design and a direct reflection of the overall technical effect of the material.

[0040] The aforementioned technical features form an interconnected and progressively layered organic whole. The sodium carboxymethyl cellulose backbone provides reaction sites and a basic framework. The physical interpenetration of polyethylene glycol and polyvinylpyrrolidone solves the problems of mechanical properties and film-forming properties, while reserving space for subsequent crosslinking. Primary crosslinking of malic acid constructs a loose primary network, allowing functional macromolecules to fully penetrate. Secondary crosslinking of citric acid locks the interpenetrated macromolecules within the network, achieving permanent structural fixation. Lactic acid molecules bind to the final microporous structure, utilizing the confined space effect to achieve highly efficient competitive capture of dicarbonyl compounds. This set of features works together to give the material high mechanical strength, good film-forming properties, excellent anti-glycation activity, and antioxidant activity, producing synergistic technical effects that cannot be achieved by a single component or simple combination.

[0041] In some embodiments, the raw materials for preparing the gel material include, by weight parts: 2-5 parts sodium carboxymethyl cellulose, 0.3-1 parts polyethylene glycol 6000, 0.5-2 parts malic acid, 0.5-2 parts polyvinylpyrrolidone, 0.3-1.5 parts lactic acid, and 0.5-2 parts citric acid, and may also include water and ethanol. In the composite cross-linked three-dimensional cellulose gel material of this application, the proportions of each raw material are key factors affecting the formation of the gel network structure and the final properties. Through extensive experimental screening, this application has determined the preferred weight ranges for the following raw materials.

[0042] The dosage of sodium carboxymethyl cellulose (CMC-Na) is 2-5 parts by weight. Sodium carboxymethyl cellulose is the backbone material constituting the three-dimensional network of the gel, and its dosage directly affects the gel's network density, mechanical strength, and swelling properties. When the dosage of sodium carboxymethyl cellulose is less than 2 parts by weight, the backbone concentration is too low, making it difficult to form a continuous and complete three-dimensional network structure, resulting in insufficient mechanical strength and stability of the gel. When the dosage of sodium carboxymethyl cellulose is greater than 5 parts by weight, the system viscosity is too high, which is not conducive to the uniform dispersion of each component and the full progress of the cross-linking reaction. It also leads to an overly hard gel, affecting its application feel on the skin. Therefore, limiting the dosage of sodium carboxymethyl cellulose to 2-5 parts by weight ensures both the integrity of the network structure and the processing performance and skin feel.

[0043] The dosage of polyethylene glycol 6000 is 0.3-1 parts by weight. As a flexible macromolecule, polyethylene glycol 6000 binds to the main chain through intercalation and hydrogen bonding, improving the gel's flexibility and moisture retention. When the dosage of polyethylene glycol 6000 is less than 0.3 parts by weight, its toughening effect on the network is not significant, and the gel is prone to cracking after drying. When the dosage of polyethylene glycol 6000 is greater than 1 part by weight, excessive polyethylene glycol occupies too much network space, interfering with subsequent cross-linking reactions, resulting in a loose gel structure and decreased mechanical strength. Therefore, limiting the dosage of polyethylene glycol 6000 to 0.3-1 parts by weight achieves a balance between toughening effect and network stability.

[0044] The amount of malic acid used is 0.5-2 parts by weight. As a primary crosslinking agent, malic acid undergoes a dehydration esterification reaction with the hydroxyl groups on the sodium carboxymethyl cellulose backbone via a dicarboxyl group, forming a preliminary linear crosslinked network. When the amount of malic acid is less than 0.5 parts by weight, the degree of crosslinking is insufficient, failing to form a stable primary network framework, making it difficult for subsequent functional macromolecules to effectively penetrate. When the amount of malic acid is greater than 2 parts by weight, excessive initial crosslinking leads to premature network densification, blocking pore channels and affecting the subsequent penetration of polyvinylpyrrolidone and lactic acid. Simultaneously, unreacted free malic acid residue increases the washing burden. Therefore, limiting the amount of malic acid to 0.5-2 parts by weight allows for the construction of a loose yet stable primary network.

[0045] The dosage of polyvinylpyrrolidone (PVP) is 0.5-2 parts by weight. PPVP enhances the density and film-forming properties of the gel by generating dipole-dipole interactions and physical entanglement with the sodium carboxymethyl cellulose (CCBC) network through its lactam structure. When the dosage of PPVP is less than 0.5 parts by weight, its densifying effect on the network is not significant, and the improvement in film-forming properties is limited. When the dosage of PPVP is greater than 2 parts by weight, excessive PPVP will overfill the network pores, inhibiting the contact between lactic acid molecules and dicarbonyl compounds, and may also lead to an overly sticky gel surface, affecting the user experience. Therefore, limiting the dosage of PPVP to 0.5-2 parts by weight can maintain a suitable pore structure while improving film-forming properties.

[0046] The dosage of lactic acid is 0.3-1.5 parts by weight. As a functionalized molecule, lactic acid binds to the micropores within the gel network through hydrogen bonds or polar interactions, competitively capturing dicarbonyl compounds and endowing the gel with anti-glycation activity. When the dosage of lactic acid is less than 0.3 parts by weight, there are insufficient active sites within the network, resulting in low capture efficiency of dicarbonyl compounds and insignificant anti-glycation effect. When the dosage of lactic acid is greater than 1.5 parts by weight, excessive lactic acid can alter the microacidic environment within the network, potentially affecting the stability of cross-linked ester bonds. Furthermore, high concentrations of lactic acid may irritate the skin. Therefore, limiting the dosage of lactic acid to 0.3-1.5 parts by weight ensures both anti-glycation activity and network stability and skin safety.

[0047] The amount of citric acid used is 0.5-2 parts by weight. Citric acid acts as a secondary crosslinking agent, forming an anhydride intermediate that undergoes a ring-opening esterification reaction with the sodium carboxymethyl cellulose backbone to construct a ternary carboxyl-branched secondary crosslinked structure, locking in the functional macromolecules within the network. When the amount of citric acid is less than 0.5 parts by weight, the degree of secondary crosslinking is insufficient, the network structure is not firmly locked, and the intercalated polyethylene glycol and polyvinylpyrrolidone are easily dissolved during subsequent processing or use, reducing the long-term stability of the gel. When the amount of citric acid is greater than 2 parts by weight, excessive secondary crosslinking leads to an overly dense network, reduced porosity, affecting the contact between lactic acid molecules and dicarbonyl compounds, and increasing the amount of unreacted citric acid residue. Therefore, limiting the amount of citric acid to 0.5-2 parts by weight can maintain suitable functional porosity while stabilizing the network structure.

[0048] The weight proportions of the above-mentioned raw materials are interconnected and synergistic. The amount of sodium carboxymethyl cellulose backbone determines the basic framework size of the network, providing a spatial basis for the binding and interpenetration of other components. The primary crosslinking of malic acid constructs a loose primary network within the framework, reserving channels for the interpenetration of polyethylene glycol and polyvinylpyrrolidone macromolecules. The interpenetration of polyethylene glycol and polyvinylpyrrolidone further modulates the flexibility and density of the network. The binding of lactic acid imparts anti-glycation function. The secondary crosslinking of citric acid locks all the above components into the final network structure. The amounts of each component need to be synergistically matched within the above-mentioned limits to achieve optimal overall performance.

[0049] In some embodiments, the composite cross-linked three-dimensional cellulose gel material of this application has a water content of less than 10% and a particle size of 80-200 mesh in the finished product form.

[0050] The moisture content of gel materials can be controlled to below 10% through a drying process. The significance of controlling the moisture content to below 10% is twofold: firstly, low moisture content promotes long-term storage stability and prevents microbial growth and hydrolysis; secondly, the low-moisture powder form facilitates dispersion and addition in subsequent skincare formulations. Furthermore, suitable moisture content ensures that the material can quickly hydrate and rehydrate upon application, forming a uniform gel state.

[0051] After being pulverized and sieved, the particle size of the gel material can be controlled between 80-200 mesh. If the particle size is too coarse (below 80 mesh), the powder will not disperse evenly in the skincare product formulation, potentially creating a grainy texture and affecting the user experience. If the particle size is too fine (above 200 mesh), the powder's specific surface area is too large, making it prone to moisture absorption and clumping. Furthermore, it causes significant dust generation during production, which is detrimental to operation and yield. The 80-200 mesh particle size range ensures good dispersibility in the formulation while also balancing ease of production and product stability.

[0052] In some embodiments, the gel material exhibits an inhibition rate of 83.8%-87.2% against advanced glycation end products (AGEs), a scavenging rate of 76.2%-80.5% against DPPH radicals, and a scavenging rate of 80.5%-84.1% against ABTS radicals.

[0053] The composite cross-linked three-dimensional cellulose gel material of this application achieves quantifiable superior performance through the synergistic effect of the above-mentioned multi-level structural design.

[0054] Based on the competitive trapping effect of lactic acid molecules on dicarbonyl compounds in the three-dimensional network structure, and the physical barrier effect of network steric hindrance on the contact between proteins and carbohydrates, the gel network of this application embodiment exhibits an inhibition rate of 83.8%-87.2% for advanced glycation end products (AGEs). Benefiting from the ability of the hydroxyl groups in the lactic acid molecules in the network structure to donate hydrogen atoms and react with DPPH free radicals, reducing them to a stable non-radical form, the gel network of this application embodiment achieves a scavenging rate of 76.2%-80.5% for DPPH free radicals.

[0055] The ABTS (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) free radical scavenging assay is another commonly used method for evaluating antioxidant activity, complementing the DPPH method. The scavenging rates of 80.5%-84.1% further confirm the excellent antioxidant activity of the gel material in this application. Compared to the DPPH method, the ABTS method is applicable to both hydrophilic and lipophilic antioxidants; the material exhibits high scavenging rates in both methods, indicating that its antioxidant activity is broad-spectrum.

[0056] like Figure 5 As shown, another embodiment of this application provides a method 200 for preparing a composite cross-linked three-dimensional cellulose gel material, the method 200 including the following steps: Step 1: Dissolve sodium carboxymethyl cellulose in deionized water and allow it to swell at 40-60℃ for 1-3 hours to obtain a sodium carboxymethyl cellulose solution.

[0057] Sodium carboxymethyl cellulose is an anionic, water-soluble polymer containing numerous hydroxyl and carboxymethyl hydrophilic groups on its molecular chain. At room temperature, the sodium carboxymethyl cellulose molecular chain is in a coiled state. By heating to 40-60℃ and holding at this temperature for 1-3 hours to allow swelling, the molecular chain gains sufficient kinetic energy, gradually extending and untangling from its coiled state, exposing the hydroxyl reaction sites on the molecular chain. Simultaneously, water molecules enter between the molecular chains through hydrogen bonding, forming a homogeneous, transparent gel-like solution.

[0058] The reason for controlling the temperature at 40-60℃ is that below 40℃, sodium carboxymethyl cellulose dissolves slowly, swelling is insufficient, and the entangled molecular chains are difficult to fully untangle, affecting the uniformity and efficiency of subsequent cross-linking reactions. Above 60℃, although the dissolution rate increases, prolonged heating may lead to localized degradation of the sodium carboxymethyl cellulose molecular chains and increase energy consumption. Controlling the swelling time to 1-3 hours ensures that sodium carboxymethyl cellulose dissolves fully and reaches swelling equilibrium; too short a time results in insufficient swelling, while too long a time reduces production efficiency.

[0059] Step 2: Add polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 40-60℃ for 10-30 minutes.

[0060] For example, polyethylene glycol is polyethylene glycol 6000, which is a nonionic linear polyether with high chain flexibility. During the homogenization process, high shear forces disperse the polyethylene glycol macromolecules into the interstices of the sodium carboxymethyl cellulose molecular chains. The ether oxygen bonds on the polyethylene glycol molecular chains form hydrogen bonds with the hydroxyl groups on the sodium carboxymethyl cellulose molecular chains, allowing the polyethylene glycol to interpenetrate between the sodium carboxymethyl cellulose backbone through physical interactions.

[0061] The key role of homogenization is to overcome the phase separation tendency commonly found in polymer blends. At temperatures of 40-60℃, the system viscosity is moderate, and the homogenizing shear force effectively mixes the two polymer chains uniformly, forming a thermodynamically metastable homogeneous mixture. At this point, although no chemical cross-linking has occurred, a relatively elastic physical hydrogel network has been formed through high-density hydrogen bonding interactions. This pre-construction of the physical network provides a spatial template for subsequent hierarchical chemical cross-linking. The homogenization time should be controlled between 10-30 minutes; too short a time results in uneven mixing, while too long a time may introduce excessive air bubbles or cause unnecessary mechanical shear degradation.

[0062] Step 3: Add malic acid to the reaction system obtained in Step 2, adjust the pH to 3.0-4.5, and react at 50-70℃ for 1-3 hours to form a preliminary cross-linked gel network.

[0063] Malic acid is a dicarboxylic acid containing two carboxyl groups in its molecule. After adding malic acid, the pH of the system is adjusted to a slightly acidic range of 3.0-4.5. Under these pH conditions, the carboxymethyl moiety on the sodium carboxymethyl cellulose molecular chain exists in the form of a free carboxylic acid, which is conducive to esterification with malic acid. Simultaneously, the slightly acidic environment also catalyzes the esterification reaction.

[0064] Under heating conditions of 50-70℃, the free carboxyl groups at both ends of malic acid undergo a dehydration esterification reaction with the primary alcohol hydroxyl groups on two adjacent sodium carboxymethyl cellulose molecular chains, forming intermolecular crosslinks. The chemical bonding mode can be represented as: sodium carboxymethyl cellulose - oxygen - carbonyl - carbon chain - carbonyl - oxygen - sodium carboxymethyl cellulose.

[0065] Because malic acid molecules are relatively short and possess only two reactive end groups, they act as linear bridges at the molecular level. This crosslinking method initially connects the free sodium carboxymethyl cellulose molecules, forming a primary three-dimensional network framework with a large free volume and porous characteristics. At this stage, the crosslinking density is low, and the entire network maintains a high degree of swelling freedom. This relatively loose primary topology provides the necessary physical space for the deep penetration and uniform distribution of polyvinylpyrrolidone and lactic acid in subsequent steps, avoiding internal spatial repulsion caused by premature network densification.

[0066] The reaction temperature is controlled at 50-70℃ and the reaction time at 1-3 hours because: below 50℃, the esterification reaction rate is too low, resulting in insufficient cross-linking; above 70℃, it may cause yellowing or degradation of sodium carboxymethyl cellulose. Too short a reaction time leads to insufficient cross-linking, while too long a time may result in over-cross-linking and an overly dense network. The pH is controlled at 3.0-4.5 because: too low a pH may cause acid-catalyzed hydrolysis of sodium carboxymethyl cellulose, destroying the main chain structure; too high a pH is detrimental to the esterification reaction.

[0067] Step 4: Add polyvinylpyrrolidone to the reaction system obtained in Step 3, and homogenize at 40-55℃ for 10-20 minutes to ensure that polyvinylpyrrolidone is uniformly dispersed in the gel network.

[0068] Polyvinylpyrrolidone (PVP) is a nonionic synthetic polymer containing a strongly polar lactam ring. During the homogenization process, PPVP molecules permeate into the pores of the primary gel network formed in step three. Its lactam structure enables dipole-dipole interactions and physical entanglement with the sodium carboxymethyl cellulose network, resulting in uniform dispersion and stable presence of PPVP within the network.

[0069] The addition of polyvinylpyrrolidone (PVP) imparts two functions to the gel. First, through the strong interaction between the lactam structure and the network, it improves the gel's density and reduces defects in the network. Second, PPVP exhibits excellent film-forming properties; its uniform dispersion significantly enhances the smoothness and film adhesion of the final material when applied to the skin surface.

[0070] The reason for controlling the homogenization temperature at 40-55℃ and the time at 10-20 minutes is that: too high a temperature or too long a time may cause structural changes or degradation of polyvinylpyrrolidone, while too low a temperature is not conducive to its uniform dispersion.

[0071] Step 5: Add lactic acid to the reaction system obtained in Step 4, and stir and mix at 40-55℃ for 20-40 minutes to ensure that the lactic acid is evenly dispersed and combines with the gel network.

[0072] Lactic acid is a short-chain α-hydroxy acid containing hydroxy and carboxyl groups. Upon addition of lactic acid, during mixing, the lactic acid molecules interact with the sodium carboxymethyl cellulose molecular chain via polar interactions or hydrogen bonds through their carboxyl groups, resulting in uniform dispersion and anchorage within the micropores of the gel network. The hydroxyl terminus of the lactic acid extends into the pores, providing active sites for the subsequent competitive capture of dicarbonyl compounds.

[0073] The mechanism of lactic acid's role in anti-glycation is as follows. Key toxic intermediates in glycation are dicarbonyl compounds, including methylglyoxal and glyoxal. These dicarbonyl compounds are far more reactive than glucose, reacting rapidly with large protein molecules to irreversibly form advanced glycation end products (AGEs). The hydroxyl groups in lactic acid molecules can undergo nucleophilic addition reactions with dicarbonyl compounds in a slightly acidic environment, consuming these toxic intermediates and thus blocking their binding to skin structural proteins.

[0074] In the preparation method of this application, lactic acid is added after polyvinylpyrrolidone dispersion and before secondary crosslinking of citric acid. This specific timing of addition has non-obvious technical significance. If lactic acid is added too early (e.g., before or simultaneously with primary crosslinking of malic acid), the carboxyl groups in the lactic acid will participate in the esterification reaction and be consumed, thus losing its functional activity. If lactic acid is added too late (e.g., after secondary crosslinking of citric acid), the network has already become dense, making it difficult for lactic acid to effectively penetrate into the internal micropores, resulting in insufficient binding. Adding lactic acid during this window period after polyvinylpyrrolidone dispersion and before secondary crosslinking of citric acid ensures that lactic acid can fully penetrate into the loose primary network while avoiding deactivation due to participation in the crosslinking reaction.

[0075] The reason for controlling the mixing temperature at 40-55℃ and the time at 20-40 minutes is that if the temperature is too low, the lactic acid will not dissolve and disperse evenly, while if the temperature is too high, the lactic acid may volatilize or decompose. If the mixing time is too short, the lactic acid will not be distributed evenly, and if the time is too long, the production efficiency will be reduced.

[0076] Step 6: Add citric acid to the reaction system obtained in Step 5 and react at 50-70℃ for 1-2 hours to stabilize and strengthen the gel network.

[0077] Citric acid is a tricarboxylic acid containing three carboxyl groups and one hydroxyl group in its molecule. Under heating conditions of 50-70℃, adjacent carboxyl groups within the citric acid molecule first undergo intramolecular dehydration, forming a highly reactive cyclic intermediate, citric anhydride. This cyclic anhydride exhibits strong electrophilicity and can rapidly attack unreacted hydroxyl groups on the sodium carboxymethyl cellulose backbone, initiating a ring-opening esterification reaction. Because citric acid possesses three reactive functional groups, it can act not only as a linear crosslinking agent but also as a branching crosslinking center, simultaneously connecting three or more polymer chains.

[0078] Based on the primary linear framework constructed by malic acid in step three, the intervention of citric acid triggers numerous secondary esterification reactions. These reactions form multiple branched crosslinking sites, locking polyethylene glycol and polyvinylpyrrolidone, which were originally only physically interspersed in the network, as well as lactic acid bound to the micropores through hydrogen bonds, into a dense network through steric hindrance and the synergistic effect of chemical bonds. This two-step crosslinking mechanism, first linear and then branched, endows the final gel material with high mechanical strength and degradation resistance.

[0079] The reason for controlling the reaction temperature at 50-70℃ and the reaction time at 1-2 hours is that: below 50℃, citric anhydride formation is difficult, making the cross-linking reaction difficult to proceed; above 70℃, hydrolysis of already formed ester bonds or degradation of the polymer may occur. If the reaction time is too short, the cross-linking will be insufficient; if the time is too long, it may lead to over-cross-linking, making the network too dense and reducing the porosity.

[0080] The primary crosslinking of malic acid in step three and the secondary crosslinking of citric acid in step six constitute the two-step hierarchical crosslinking system of this application. The selection and addition sequence of the two crosslinking agents have a clear synergistic effect. As a dicarboxylic acid, malic acid has a mild crosslinking ability, and the primary network it constructs is relatively loose, leaving room for the insertion of functional macromolecules. As a tricarboxylic acid, citric acid has a strong crosslinking ability, and the secondary network it constructs is dense and has a branched structure, locking the functional components inside the network. The combined use of the two crosslinking agents avoids the problem of excessively rapid initial network contraction when using citric acid alone, which makes it difficult to wash away impurities and for functional molecules to penetrate, and also makes up for the lack of network stability when using malic acid alone.

[0081] Step 7: Adjust the pH of the system to 5.5-6.5.

[0082] After the aforementioned cross-linking reaction, unreacted free acid may remain in the system, placing the gel in an acidic environment. The pH of healthy human skin is typically between 5.5 and 6.5. Adjusting the pH of the gel material to this range can prevent skin irritation during product use. Simultaneously, a slightly acidic to neutral pH environment is beneficial for the long-term stability of the cross-linked ester bonds, preventing hydrolysis under excessively acidic or alkaline conditions.

[0083] Step 8: Wash, dry, pulverize, and sieve the reaction product to obtain the composite cross-linked three-dimensional cellulose gel material.

[0084] Steps one through eight constitute a complete preparation process, and the sequence of each step is strictly sequential and cannot be arbitrarily changed. Step one, swelling, allows the sodium carboxymethyl cellulose molecular chains to fully extend. Step two, polyethylene glycol homogenization, allows flexible macromolecules to interweave between the main chains. Step three, primary cross-linking with malic acid, constructs a loose primary network. Step four, homogenization with polyvinylpyrrolidone, allows film-forming macromolecules to penetrate into the network pores. Step five, lactic acid mixing, anchors functional molecules within the micropores. Step six, secondary cross-linking with citric acid, locks all the above components within a dense network. Step seven, pH adjustment, ensures the product's skin safety. Step eight, post-processing, yields the finished product. This specific sequential arrangement is one of the core technical features of the preparation method in this application and is key to achieving the synergistic effect of multiple components.

[0085] The gel material of this application forms a stable internal network through unconventional two-stage continuous chemical cross-linking and the interpenetration of physical macromolecules. This specific physical topology greatly enriches active reaction sites such as lactic acid, and through a synergistic mechanism of concentration accumulation effect and chemical competitive inhibition, it increases the local collision frequency of free dicarbonyl compounds that cause glycation reactions, effectively intercepting and consuming toxic glycation intermediates.

[0086] Compared with the prior art, this application has the following beneficial effects.

[0087] First, the gel material of this application exhibits excellent anti-glycation and antioxidant activity. Its inhibition rate of advanced glycation end products (AGEs) is no less than 80%, significantly superior to the 32.5% of ordinary sodium carboxymethyl cellulose gel and the 62.8% of commercially available anti-glycation products. This activity originates from the steric hindrance effect of the three-dimensional network, the competitive capture of dicarbonyl compounds by lactic acid, and the amplification effect of the microporous confinement space on the capture efficiency. The material of this application also exhibits a DPPH radical scavenging rate of no less than 75%, this activity stemming from the hydrogen atom donation capability provided by the hydroxyl groups in the lactic acid molecule.

[0088] Second, this application employs a multi-component composite crosslinking technology involving polyethylene glycol (PEG) intercalation, primary crosslinking with malic acid, dispersion with polyvinylpyrrolidone (PVP), and secondary crosslinking with citric acid. PEG imparts flexibility and moisturizing properties to the gel; malic acid constructs a loose primary network, reserving space for the penetration of functional molecules; PVP enhances film-forming properties and skin feel; and citric acid forms branched crosslinking centers, locking each component within the network. This two-step crosslinking mechanism, first linear and then branched, achieves spatial anchoring and functional integration of the multi-component components.

[0089] Third, the preparation conditions in this application are mild, with the reaction temperature not exceeding 70°C throughout the process, and there is no need to use toxic crosslinking agents such as glutaraldehyde. By achieving low-temperature esterification crosslinking under slightly acidic conditions of pH 3.0-4.5, the thermal degradation and yellowing of natural polymers caused by high-temperature treatment are avoided, thus reducing energy consumption and equipment requirements.

[0090] Fourth, all raw materials used in this application are food-grade or cosmetic-grade safe substances with good safety and biocompatibility. Lactic acid is an endogenous α-hydroxy acid, bound within the three-dimensional network rather than added in free form, thus avoiding skin irritation that may be caused by high concentrations of lactic acid.

[0091] Fifth, through the dispersion and anchoring of polyvinylpyrrolidone, the material exhibits good spreadability and film-forming properties on the skin. The interpenetration of polyethylene glycol imparts flexibility to the material, and the dry powder can quickly hydrate and revert to form a uniform gel upon use, giving the gel material of this application excellent performance and skin feel.

[0092] In some embodiments, step eight, washing the reaction product includes: first washing 2-3 times with 50% ethanol solution at a solid-liquid ratio of 1:4, and then washing 2-3 times with 90% ethanol solution at a solid-liquid ratio of 1:3.

[0093] In this embodiment, a gradient ethanol washing method is used to remove unreacted raw materials and impurities. High-concentration ethanol is a poor solvent, which can induce mild volume shrinkage and dehydration in the water-rich sodium carboxymethyl cellulose crosslinked network. Gradual dehydration prevents the network from collapsing abruptly due to sudden changes in osmotic pressure. In a static or slowly flowing solution, a stable hydrodynamic boundary layer forms on the surface of the gel micropores, which severely hinders the diffusion of internal impurities to the external solvent.

[0094] In some embodiments, the ethanol washing process is carried out in conjunction with a stirring and vibration system, wherein the stirring speed is 10-30 rpm, and the stirring method is adopted, with a cycle of stirring for 5 minutes and letting stand for 2 minutes; the vibration frequency is 20-50 Hz, the amplitude is 1-3 mm, and the vibration method is adopted, with a cycle of vibrating for 3 minutes and letting stand for 2 minutes.

[0095] In this embodiment, during the gradient ethanol washing process, low-frequency vibrations of 20-50 Hz are applied. These mechanical vibrations transfer low-frequency kinetic energy to the fluid phase, inducing microscopic fluid disturbances at the gel-solvent interface and within the capillary channels, resulting in localized acoustic cavitation in the microporous region. This microscopic fluid disturbance directly disrupts the mass transfer resistance layer, increasing the convective mass transfer coefficient and allowing impurity molecules deep within the pores to be rapidly expelled from the gel under the drive of the concentration gradient. Simultaneously, the macroscopic displacement of the vibration, combined with low-speed stirring, avoids macroscopic shear tearing caused by turbine stirrers. The intermittent mode of 3 minutes of vibration followed by 2 minutes of rest allows sufficient time for the fluid to achieve solute reequilibrium, preventing polymer chain mechanical fatigue fracture that might be caused by continuous vibration.

[0096] In some embodiments, the drying in step eight includes transferring the washed gel to a vacuum rake dryer and drying it under vacuum conditions at 50-60°C until the moisture content is less than 10%. Vacuum drying is carried out at a lower temperature, avoiding yellowing or degradation that may be caused by high-temperature drying, while improving drying efficiency.

[0097] In some embodiments, the pulverization and sieving in step eight includes: pulverizing the dried gel and passing it through an 80-200 mesh sieve to obtain the finished composite cross-linked three-dimensional cellulose gel material. Controlling the particle size within the 80-200 mesh range ensures good dispersion of the powder in skincare product formulations while also taking into account the convenience of production operations and the stability of the product.

[0098] This application also provides the application of the above-mentioned composite cross-linked three-dimensional cellulose gel material in the preparation of anti-glycation skin care products or antioxidant skin care products.

[0099] The composite cross-linked three-dimensional cellulose gel material of this application exhibits excellent anti-glycation and antioxidant activities, and can be directly added to various skin care product formulations as a functional ingredient. This material itself combines the physical excipient function of a hydrogel matrix with the bioactive functions of anti-glycation and anti-oxidation, making it a novel cosmetic functional ingredient that integrates carrier and active ingredient.

[0100] This material is applicable to skincare products containing, but is not limited to, serums, masks, creams, eye creams, lotions, toners, and skincare gels. In these formulations, the material can simultaneously act as a thickener, film-forming agent, or moisturizing matrix, achieving anti-glycation and antioxidant effects without the need for additional multifunctional ingredients.

[0101] The recommended addition level of this material in skincare formulations is 0.5% to 5% (by weight), with the specific amount adjustable based on product positioning and expected efficacy. Adding levels below 0.5% will not have a significant anti-glycation effect, while adding levels above 5% may affect the formula's fluidity and texture.

[0102] The method of using this material is as follows: The composite cross-linked three-dimensional cellulose gel material powder is directly added to the aqueous phase of the skincare product formulation, and stirred and dispersed at room temperature or under heating conditions until completely dissolved. Subsequent formulation is then carried out according to conventional processes. This material exhibits good compatibility with commonly used excipients in the cosmetics field, such as moisturizers, emulsifiers, oils, and preservatives, requiring no special processing.

[0103] The technical solutions, process details, and beneficial effects of this application are further illustrated below with reference to specific embodiments and comparative examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application.

[0104] The performance indicators of the products obtained in the following embodiments and comparative examples were all measured using the methods described below.

[0105] The inhibition rate of advanced glycation end products (AGEs) in the samples was determined using a bovine serum albumin-glucose in vitro glycation model.

[0106] Test Method: Bovine serum albumin (BSA) was dissolved in 0.2 mol / L phosphate buffer to prepare a 10 mg / mL BSA solution. Glucose was dissolved in the same phosphate buffer to prepare a 50 mmol / L glucose solution. The test sample was prepared into a 1 mg / mL test solution using phosphate buffer. In a 96-well plate, 50 μL of BSA solution, 50 μL of glucose solution, and 50 μL of test solution were added to each well and mixed thoroughly. Wells containing an equal volume of phosphate buffer without the test sample served as blank controls, and wells without glucose served as background controls. The 96-well plate was incubated at 37°C in the dark for 72 hours. After incubation, the fluorescence intensity of each well was measured using a fluorescence microplate reader at an excitation wavelength of 370 nm and an emission wavelength of 440 nm. The inhibition rate of advanced glycosylation products (AGEs) was calculated using the following formula: Inhibition rate (%) = (Fluorescence intensity of blank control group - Fluorescence intensity of sample group) / (Fluorescence intensity of blank control group - Fluorescence intensity of background control group) × 100%. Each sample was measured in triplicate, and the average value was taken.

[0107] The antioxidant activity of the samples was determined using a DPPH free radical scavenging assay.

[0108] Test Method: Accurately weigh DPPH, dissolve and dilute with anhydrous ethanol to a 0.1 mmol / L DPPH working solution, and store protected from light. Prepare a 1 mg / mL test solution from the sample using deionized water. Add 100 μL of DPPH working solution and 100 μL of test solution to each well of a 96-well plate and mix thoroughly. Use wells containing 100 μL of DPPH working solution and 100 μL of anhydrous ethanol as blank controls, and wells containing 100 μL of test solution and 100 μL of anhydrous ethanol as sample background controls. Incubate the 96-well plate at room temperature in the dark for 30 minutes. After the reaction, measure the absorbance of each well at 517 nm using a microplate reader. The DPPH free radical scavenging rate is calculated using the following formula: Scavenging rate (%) = (1 - (Absorbance of sample group - Absorbance of sample background group) / Absorbance of blank control group) × 100%. Each sample is measured in triplicate, and the average value is taken.

[0109] The antioxidant activity of the samples was determined using the ABTS free radical scavenging assay.

[0110] Test Method: Prepare a 7 mmol / L ABTS stock solution by dissolving ABTS in deionized water. Prepare a 2.45 mmol / L potassium persulfate solution by dissolving potassium persulfate in deionized water. Mix equal volumes of the ABTS stock solution and potassium persulfate solution and react at room temperature in the dark for 12 to 16 hours to generate the ABTS cationic radical working solution. Before use, dilute the ABTS cationic radical working solution with anhydrous ethanol to a working solution with an absorbance of 0.70 ± 0.02 at 734 nm. Prepare a 1 mg / mL test solution from the sample to be tested using deionized water. Add 180 μL of ABTS working solution and 20 μL of test solution to each well of a 96-well plate and mix thoroughly. Use wells containing 180 μL of ABTS working solution and 20 μL of deionized water as blank controls. Incubate the 96-well plate at room temperature in the dark for 6 minutes. After the reaction, measure the absorbance of each well at 734 nm using a microplate reader. The ABTS free radical scavenging rate was calculated using the following formula: Scavenging rate (%) = (Absorbance of blank control group - Absorbance of sample group) / Absorbance of blank control group × 100%. Each sample was measured in triplicate, and the average value was taken.

[0111] Example 1 A method for preparing a composite cross-linked three-dimensional cellulose gel material includes the following steps.

[0112] Step 1: Raw material pretreatment: Weigh 3g of sodium carboxymethyl cellulose, dissolve it in 200mL of deionized water, and swell at 50℃ for 2 hours to obtain a uniform sodium carboxymethyl cellulose solution.

[0113] Step 2: Add polyethylene glycol and homogenize: Add 60000.5g of polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 50°C for 20 minutes.

[0114] Step 3: Primary cross-linking of malic acid: Add 1g of malic acid to the reaction system, adjust the pH to 3.5, and react at 60℃ for 2 hours.

[0115] Step 4: Add polyvinylpyrrolidone and homogenize: Add 1g of polyvinylpyrrolidone to the reaction system and homogenize at 45°C for 15 minutes.

[0116] Step 5: Add lactic acid to dissolve and mix: Add 0.8g of lactic acid to the reaction system and stir and mix at 45℃ for 30 minutes.

[0117] Step 6: Secondary cross-linking of citric acid: Add 1g of citric acid to the reaction system and react at 60℃ for 1.5 hours.

[0118] Step 7: pH adjustment: Adjust the pH of the system to 6.0.

[0119] Step 8: Transfer the gel to a washing tank, add 400 mL of 50% ethanol solution, start stirring at 20 rpm and vibrating at 30 Hz, wash for 15 minutes, let stand for 5 minutes, then drain the waste liquid. Repeat the above operation twice. Then add 300 mL of 90% ethanol solution, start stirring at 15 rpm and vibrating at 25 Hz, wash for 15 minutes, let stand for 5 minutes, then drain the waste liquid. Repeat the above operation twice. Transfer the washed gel to a vacuum rake dryer and dry at 55℃ under vacuum for 8 hours until the moisture content is less than 10%. Pulverize the dried gel and pass it through a 100-mesh sieve to obtain the composite cross-linked three-dimensional cellulose gel material.

[0120] The performance indicators of the obtained product are as follows: appearance is white to light yellow powder, particle size is 100 mesh, moisture content is 8.5%, late glycosylation advanced product inhibition rate is 85.6%, DPPH free radical scavenging rate is 78.5%, and ABTS free radical scavenging rate is 82.3%.

[0121] Example 2 A method for preparing a composite cross-linked three-dimensional cellulose gel material includes the following steps.

[0122] Step 1: Raw material pretreatment: Weigh 4g of sodium carboxymethyl cellulose, dissolve it in 250mL of deionized water, and allow it to swell at 55℃ for 2.5 hours.

[0123] Step 2: Add polyethylene glycol and homogenize: Add 60000.6g of polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 55°C for 25 minutes.

[0124] Step 3: Primary cross-linking of malic acid: Add 1.5g of malic acid to the reaction system, adjust the pH to 3.8, and react at 65℃ for 2.5 hours.

[0125] Step 4: Add polyvinylpyrrolidone and homogenize: Add 1.2g of polyvinylpyrrolidone to the reaction system and homogenize at 48℃ for 18 minutes.

[0126] Step 5: Add lactic acid to dissolve and mix: Add 1g of lactic acid to the reaction system and stir and mix at 48℃ for 35 minutes.

[0127] Step 6: Secondary cross-linking of citric acid: Add 1.2g of citric acid to the reaction system and react at 65℃ for 1.8 hours.

[0128] Step 7: pH adjustment: Adjust the pH of the system to 5.8.

[0129] Step 8: Use the same washing process as in Example 1. Dry at 58°C under vacuum for 7 hours. After pulverizing, pass through a 150-mesh sieve.

[0130] The performance indicators of the obtained product are as follows: inhibition rate of advanced glycation end products 87.2%, DPPH radical scavenging rate 80.5%, and ABTS radical scavenging rate 84.1%.

[0131] Example 3 A method for preparing a composite cross-linked three-dimensional cellulose gel material includes the following steps.

[0132] Step 1: Raw material pretreatment: Weigh 2.5g of sodium carboxymethyl cellulose, dissolve it in 180mL of deionized water, and allow it to swell at 45℃ for 1.5 hours.

[0133] Step 2: Add polyethylene glycol and homogenize: Add 60000.4g of polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 45°C for 15 minutes.

[0134] Step 3: Primary cross-linking of malic acid: Add 0.8g of malic acid to the reaction system, adjust the pH to 3.2, and react at 55℃ for 1.5 hours.

[0135] Step 4: Add polyvinylpyrrolidone and homogenize: Add 0.8 g of polyvinylpyrrolidone to the reaction system and homogenize at 42 °C for 12 minutes.

[0136] Step 5: Add lactic acid to dissolve and mix: Add 0.6g of lactic acid to the reaction system and stir and mix at 42℃ for 25 minutes.

[0137] Step 6: Secondary cross-linking of citric acid: Add 0.8g of citric acid to the reaction system and react at 55℃ for 1.2 hours.

[0138] Step 7: pH adjustment: Adjust the pH of the system to 5.6.

[0139] Step 8: Use the same washing process as in Example 1. Dry at 52°C under vacuum for 9 hours. After pulverizing, pass through an 80-mesh sieve.

[0140] The performance indicators of the obtained products are as follows: 83.8% inhibition rate of advanced glycation end products, 76.2% DPPH radical scavenging rate, and 80.5% ABTS radical scavenging rate.

[0141] Comparative Example 1 Ordinary sodium carboxymethyl cellulose gel: Sodium carboxymethyl cellulose is dissolved in deionized water, dried and pulverized directly without cross-linking treatment.

[0142] The test results showed that the inhibition rate of advanced glycation end products was 32.5%, and the DPPH radical scavenging rate was 25.8%.

[0143] Comparative Example 2 Single crosslinked gel: Crosslinking is performed using only malic acid, without the addition of polyethylene glycol, polyvinylpyrrolidone, lactic acid, and citric acid, and other conditions are the same as in Example 1.

[0144] The test results showed that the inhibition rate of advanced glycation end products was 52.6%, and the DPPH radical scavenging rate was 45.2%.

[0145] Comparative Example 3 Polyethylene glycol-free crosslinking gel: without the addition of polyethylene glycol 6000, other conditions are the same as in Example 1.

[0146] The test results showed that the inhibition rate of advanced glycation end products was 72.5%, the DPPH free radical scavenging rate was 65.8%, and the moisturizing effect decreased.

[0147] Comparative Example 4 Citric acid-free secondary crosslinking gel: No secondary crosslinking with citric acid is performed, and other conditions are the same as in Example 1.

[0148] The test results showed that the inhibition rate of advanced glycation end products was 68.5%, the DPPH radical scavenging rate was 62.3%, and the stability decreased.

[0149] Comparative Example 5 Commercially available anti-glycation product A.

[0150] The test results showed that the inhibition rate of advanced glycation end products was 62.8%, and the DPPH radical scavenging rate was 58.2%.

[0151] Comparative Example 6 The preparation method for a gel material in which the crosslinking order of malic acid and citric acid is reversed during the preparation process includes: (1) Raw material pretreatment: Weigh 3g of sodium carboxymethyl cellulose, dissolve it in 200mL of deionized water, and swell at 50℃ for 2 hours to obtain a uniform sodium carboxymethyl cellulose solution.

[0152] (2) Add polyethylene glycol and homogenize: Add 0.5 g of polyethylene glycol 6000 to the sodium carboxymethyl cellulose solution and homogenize at 50°C for 20 minutes.

[0153] (3) Citric acid crosslinking: Add 1g of citric acid to the reaction system, adjust the pH to 3.5, and react at 60℃ for 1.5 hours.

[0154] (4) Add polyvinylpyrrolidone and homogenize: Add 1g of polyvinylpyrrolidone to the reaction system and homogenize at 45°C for 15 minutes.

[0155] (5) Add lactic acid to dissolve and mix: Add 0.8g of lactic acid to the reaction system and stir and mix at 45°C for 30 minutes.

[0156] (6) Secondary crosslinking of malic acid: Add 1g of malic acid to the reaction system and react at 60℃ for 2 hours.

[0157] (7) pH adjustment: Adjust the pH of the system to 6.0.

[0158] Step 8: Use the same gradient ethanol washing process as in Example 1. Dry at 55°C under vacuum for 8 hours, then pulverize and pass through a 100-mesh sieve.

[0159] In this comparative example, the crosslinking order was reversed. Citric acid was added first for primary crosslinking, and malic acid was added for secondary crosslinking. All other conditions were exactly the same as in Example 1.

[0160] The test results showed that the inhibition rate of advanced glycation end products (AGEs) was 68%, the DPPH radical scavenging rate was 61%, and the ABTS radical scavenging rate was 66%. Comparative Example 7 Gel materials that are not washed with gradient ethanol Steps one through seven of the preparation method are the same as in Example 1. In the washing step of step eight, 400 mL of 90% ethanol solution is added, the stirring speed is started at 20 rpm and the vibration frequency at 30 Hz, and the mixture is washed for 15 minutes. After standing for 5 minutes, the waste liquid is drained. This operation is repeated twice. Then, 300 mL of 90% ethanol solution is added, the stirring speed is started at 15 rpm and the vibration frequency at 25 Hz, and the mixture is washed for 15 minutes. After standing for 5 minutes, the waste liquid is drained. This operation is repeated twice. The remaining steps of step eight are the same as in Example 1.

[0161] The test results showed that the inhibition rate of advanced glycation end products was 76%, the DPPH radical scavenging rate was 69%, and the ABTS radical scavenging rate was 74%.

[0162] Comparative Example 8: Gel material without lactic acid The difference between this comparative example and Example 1 is that lactic acid is not added, that is, step five in Example 1 is omitted, while the remaining steps are the same as in Example 1.

[0163] The test results showed that the inhibition rate of advanced glycation end products was 72%, the DPPH radical scavenging rate was 55%, and the ABTS radical scavenging rate was 60%.

[0164] Comparative Example 9: Gel material without polyethylene glycol and polyvinylpyrrolidone The difference between this comparative example and Example 1 is that polyethylene glycol and polyvinylpyrrolidone are not added, that is, steps two and four in Example 1 are omitted, while the remaining steps are the same as in Example 1.

[0165] The test results showed that the inhibition rate of advanced glycation end products was 77%, the DPPH radical scavenging rate was 72%, and the ABTS radical scavenging rate was 76%.

[0166] The test results from the above examples and comparative examples show that the anti-glycation activity and antioxidant activity of the composite cross-linked three-dimensional cellulose gel material prepared in this application are significantly better than those of the comparative products, demonstrating the synergistic effect of the multi-component cross-linking technology. Specifically, the inhibition rate of advanced glycation end products (AGEs) of ordinary sodium carboxymethyl cellulose gel is only 32.5%, while that of single malic acid cross-linked gel is increased to 52.6%, that of polyethylene glycol-free cross-linked gel is increased to 72.5%, and that of citric acid-free secondary cross-linked gel is 68.5%, while the complete formulation product of this application reaches 83.8% to 87.2%. This indicates that only in composite materials that have fully realized interpenetrating networks, dual hierarchical cross-linking, and lactic acid micropool modification does the inhibition rate of AGEs exhibit a sudden leap, while the antioxidant activity is also significantly improved simultaneously. This increase in bioactivity is not a simple summation of the properties of each component, but rather due to the amplification effect of the specific network physical topology on the retention efficiency of chemical reactions.

[0167] As can be seen from the comparison between Comparative Example 6 and the Examples, the reversal of the crosslinking sequence disrupts the core design logic of first constructing a loose network for macromolecules to penetrate, and then densifying and locking them in place. This results in the inability of functional molecules to be effectively loaded, and a significant decrease in anti-glycation and antioxidant properties. Specifically, citric acid is a tricarboxylic acid with higher reactivity than malic acid. When citric acid is added in the first step, its three carboxyl groups rapidly undergo multi-point crosslinking with the sodium carboxymethyl cellulose backbone, forming a dense network structure. This premature densification causes the following problems: First, the network becomes dense in the early stages, with a significant reduction in porosity and pore size. The subsequently added polyvinylpyrrolidone and lactic acid cannot effectively penetrate into the network, resulting in uneven dispersion of polyvinylpyrrolidone and a reduced binding amount of lactic acid. Second, because polyvinylpyrrolidone and lactic acid cannot fully penetrate into the network, the subsequently added malic acid can only undergo further crosslinking reactions on the network surface or in the shallow layer, failing to achieve uniform locking within the network. Third, the secondary crosslinking effect of malic acid is weakened because most of the reaction sites have already been consumed in the primary crosslinking of citric acid.

[0168] Comparative Example 7 was washed directly with 90% ethanol. When the gel comes into direct contact with 90% high-concentration ethanol, the gel network surface undergoes severe and non-uniform volume shrinkage due to strong dehydration, forming a dense surface layer, because high-concentration ethanol is a poor solvent for sodium carboxymethyl cellulose. This dense layer rapidly blocks the pore channels inside the gel. Although this comparative example also used a vibration system, with the network surface already blocked, the micro-perturbations generated by vibration were difficult to effectively transmit to the gel core region, and could not open the closed mass transfer channels. In this case, the first wash (400 mL, 90% ethanol) mainly acted on the gel surface, which could wash away free impurities on the surface, but could not effectively penetrate into the gel interior. The two repeated operations after the first wash showed a rapid decrease in washing efficiency due to the collapsed and dense network surface. Although vibration was still used in the second wash (300 mL, 90% ethanol), the ethanol solvent could only circulate on the periphery at this time, and could not remove unreacted malic acid, citric acid, and unanchored lactic acid molecules from the gel core region. This uneven washing effect leads to two problems. First, the free acids remaining inside the gel may catalyze localized transesterification or degradation reactions during subsequent vacuum drying. Simultaneously, residual lactic acid and other organic matter may undergo Maillard reactions under heating conditions, resulting in an uneven pale yellow product color. Second, due to the drastic shrinkage of the gel surface during washing, some lactic acid molecules that should have been evenly distributed within the network are physically squeezed to the gel surface and lost with the washing solution. This results in an uneven distribution of lactic acid within the gel, with less on the surface and more in the interior, and a decrease in the total loading. This loss and uneven distribution of lactic acid is the main reason why the anti-glycation activity of Comparative Example 7 is lower than that of Example 1. In contrast, the gradient ethanol washing method used in Example 1 (50% ethanol first, then 90% ethanol) allows the gel to undergo a gentle, gradual dehydration process. The osmotic pressure of 50% ethanol is closer to the internal environment of the gel. During this stage, the gel network remains open, and the vibration system can effectively remove impurities deep within the micropores. After most of the free impurities are removed, the final dehydration is carried out with 90% ethanol. At this point, since the core impurities have been largely removed, the impact of network shrinkage on the distribution of functional components is also greatly reduced. As can be seen from Comparative Example 7 and the Examples, the specific concentration gradient design of first washing with a low concentration (50%) to keep the network open, followed by dehydration and shrinkage with a high concentration (90%), protects the integrity of the three-dimensional network structure and the uniform distribution of lactic acid molecules. This is a hidden but crucial contributing factor to achieving excellent anti-glycation performance.

[0169] Comparative Example 8 maintained a certain level of anti-glycation activity because the steric hindrance effect of the gel three-dimensional network itself physically blocked the contact between proteins and carbohydrates. Simultaneously, the free carboxyl groups remaining in the network after the crosslinking of malic acid and citric acid may also produce a small amount of non-specific adsorption of dicarbonyl compounds. However, due to the lack of hydroxyl active sites provided by lactic acid molecules, efficient competitive capture of dicarbonyl compounds could not be achieved, thus the anti-glycation activity of Comparative Example 8 decreased. Regarding antioxidant activity, the DPPH scavenging rate of Comparative Example 8 decreased significantly, from 78.5% in Example 1 to approximately 55%. This is because lactic acid is the main contributor to the antioxidant activity in this system. The hydroxyl groups in the lactic acid molecule can provide hydrogen atoms to react with free radicals, reducing them to a stable form. Without lactic acid, the antioxidant capacity of sodium carboxymethyl cellulose, polyethylene glycol, and polyvinylpyrrolidone was weak, and they could not effectively scavenge DPPH free radicals. Regarding the synergistic effect, the performance difference between Comparative Example 8 and Example 1 demonstrates that lactic acid is a key functional molecule that synergizes with the three-dimensional network structure. The micropores of the network anchor lactic acid, enabling it to form high-concentration active regions locally, thus achieving efficient capture of dicarbonyl compounds. Without lactic acid, although the network structure itself exists, it lacks functional active centers, and its anti-glycation and antioxidant properties cannot reach optimal levels. Furthermore, the absence of lactic acid also affects the pH adjustment and skin safety of the material. The addition of lactic acid helps adjust the system pH to a skin-friendly range of 5.5-6.5; without lactic acid, an additional amount of acidity regulator is required. Comparative Example 8 demonstrates that lactic acid is an essential component of this application, and its presence or absence has a decisive impact on the anti-glycation and antioxidant properties of the material.

[0170] The gel material without polyethylene glycol and polyvinylpyrrolidone showed a slight decrease in anti-glycation and antioxidant activity compared to Example 1, but the difference was not significant. However, it exhibited a significant deterioration in physical properties and user experience. The anti-glycation activity of Comparative Example 9 was slightly lower than that of Example 1. This is because polyethylene glycol and polyvinylpyrrolidone have limited direct contributions to the AGEs inhibition rate, but they optimize the network's pore structure through interpenetration and dispersion, indirectly providing a more favorable loading microenvironment for lactic acid. Without these two macromolecules, the network structure is relatively simple, and the uniformity and spatial distribution of lactic acid loading may be affected, leading to a slight decrease in anti-glycation efficiency. The antioxidant activity of Comparative Example 9 also decreased slightly. While polyethylene glycol and polyvinylpyrrolidone are not potent antioxidants themselves, their absence has a relatively small direct impact on antioxidant activity. However, the lack of their optimization effect on the network structure may cause local aggregation or uneven distribution of lactic acid during drying and rehydration, affecting the stable performance of antioxidant activity. In terms of material physical properties, the most prominent problems resulting from the absence of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) are in the mechanical properties and actual user experience. The lack of PEG results in a lack of the toughening effect of the flexible components in the gel, leading to a harder powder texture after drying, which easily produces fine powder during pulverization and reduces the yield after sieving. More importantly, when the powder is rehydrated to form a gel, the lack of film-forming properties provided by PPV is insufficient, resulting in an uneven gel texture, poor spreadability when applied to the skin, and a discontinuous and flaky film after drying. The absence of PEG also reduces the material's moisturizing properties; the rehydrated gel has weak water retention capacity, and the gel dries and hardens rapidly after water evaporation. Regarding process operability, without PPV, the viscosity of the system after the first crosslinking of malic acid in step three is low, which is not conducive to the uniform dispersion of subsequent lactic acid and citric acid. The presence of PEG and PPV increases the initial viscosity of the system, helping to maintain the uniform suspension of each component. Comparative Example 9 demonstrates that while polyethylene glycol and polyvinylpyrrolidone (PVP) have limited direct contributions to anti-glycation activity, they play an irreplaceable role in improving the material's flexibility, film-forming properties, moisturizing properties, and user experience. Without these two macromolecules, the material retains some anti-glycation activity but loses the desirable skin feel and performance characteristics necessary for its efficacy as a cosmetic ingredient, making it difficult to meet the application requirements of high-end skincare products. Therefore, polyethylene glycol and PPV are essential components of this application.

[0171] Application Example 1: Anti-glycation serum Take 2g of the composite cross-linked three-dimensional cellulose gel material prepared in Example 1, add 80g of deionized water, and stir at room temperature until completely dissolved to form a uniform gel-like base solution. Add 5g of glycerin, 3g of butylene glycol, 0.1g of sodium hyaluronate, and an appropriate amount of preservative to the above base solution, and continue stirring to mix evenly. Adjust the pH to 5.8-6.2 with citric acid or sodium hydroxide, and add water to 100g to obtain an anti-glycation essence.

[0172] The resulting serum is a colorless to slightly yellow transparent gel-like liquid that spreads well and forms a film on the skin. In vitro anti-glycation activity tests showed that the serum containing 2% of the material described in this application exhibited an inhibition rate of over 75% against advanced glycation end products (AGEs).

[0173] Application Example 2: Antioxidant Repairing Facial Mask Liquid Take 3g of the composite cross-linked three-dimensional cellulose gel material prepared in Example 2, add 75g of deionized water, and stir to disperse until completely dissolved at room temperature. Add 5g of propylene glycol, 2g of trehalose, 0.2g of allantoin, and an appropriate amount of preservative to the above solution, and stir to mix evenly. Adjust the pH to 5.5-6.5 with citric acid or sodium hydroxide, and add water to 100g to obtain an antioxidant repairing mask liquid.

[0174] The resulting mask liquid can be used as an impregnation solution for non-woven fabric masks or applied directly to the face. In vitro antioxidant activity tests showed that the mask liquid containing 3% of the material described in this application achieved a scavenging rate of over 70% for DPPH free radicals and over 75% for ABTS free radicals.

[0175] To further illustrate the application effect of the materials in skin care products, the anti-glycation essence prepared in accordance with Case 1 was subjected to human efficacy evaluation test.

[0176] Test Method: Thirty healthy female volunteers aged 35-55 with fine lines around the eyes and dull skin were selected. They applied the anti-glycation serum prepared in Example 1 to their faces twice daily, morning and evening, for 8 consecutive weeks. Changes in skin elasticity and skin tone brightness before and after use were measured using a skin elasticity tester and a skin color tester, respectively.

[0177] Test results: After 4 weeks of use, subjects' skin elasticity improved by an average of 12.3%, and skin tone brightness improved by an average of 8.7%. After 8 weeks of use, skin elasticity improved by an average of 21.6%, and skin tone brightness improved by an average of 15.4%. More than 95% of subjects reported that fine lines around the eyes were reduced, and overall skin condition improved.

[0178] It is evident that the composite cross-linked three-dimensional cellulose gel material of this application, when added to skin care products as a functional ingredient, can effectively exert anti-glycation and antioxidant effects, and improve skin elasticity and dull skin tone.

[0179] Principles and steps not explicitly described in this application are all obtainable by those skilled in the art through conventional technical means, and therefore will not be elaborated upon. Obviously, those skilled in the art can make various modifications and variations to this application without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A composite cross-linked three-dimensional cellulose gel material, characterized in that, The gel material has a three-dimensional cross-linked gel network with sodium carboxymethyl cellulose as the main chain. Polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) macromolecules are interwoven and physically bonded within the main chain. The main chain is sequentially subjected to malic acid via dicarboxyl dehydration esterification to form a primary linear cross-linked structure, followed by citric acid via a ring-opening reaction to form an anhydride intermediate, constructing a ternary carboxyl branched secondary cross-linked structure. This locks the PEG and PPVP macromolecules within the gel network. Lactic acid molecules, which competitively capture dicarbonyl compounds, are bonded to the micropores within the gel network via hydrogen bonds or polar interactions. The gel material exhibits an inhibition rate of at least 80% for advanced glycation end products (AGEs) and a scavenging rate of at least 75% for DPPH free radicals.

2. The composite cross-linked three-dimensional cellulose gel material according to claim 1, characterized in that, The raw materials for preparing the gel material include, by weight, 2-5 parts sodium carboxymethyl cellulose, 0.3-1 parts polyethylene glycol, 0.5-2 parts malic acid, 0.5-2 parts polyvinylpyrrolidone, 0.3-1.5 parts lactic acid, and 0.5-2 parts citric acid.

3. The composite cross-linked three-dimensional cellulose gel material according to claim 1 or 2, characterized in that, The gel material has a water content of less than 10% and a particle size of 80-200 mesh.

4. The composite cross-linked three-dimensional cellulose gel material according to claim 1 or 2, characterized in that, The gel material exhibits an inhibition rate of 83.8%-87.2% against advanced glycation end products (AGEs), a scavenging rate of 76.2%-80.5% against DPPH radicals, and a scavenging rate of 80.5%-84.1% against ABTS radicals.

5. A method for preparing a composite cross-linked three-dimensional cellulose gel material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Dissolve sodium carboxymethyl cellulose in deionized water and allow it to swell at 40-60℃ for 1-3 hours to obtain a sodium carboxymethyl cellulose solution; Step 2: Add polyethylene glycol to the sodium carboxymethyl cellulose solution and homogenize at 40-60°C for 10-30 minutes; Step 3: Add malic acid to the reaction system obtained in Step 2, adjust the pH to 3.0-4.5, and react at 50-70℃ for 1-3 hours to form a preliminary cross-linked gel network; Step 4: Add polyvinylpyrrolidone to the reaction system obtained in Step 3, and homogenize at 40-55℃ for 10-20 minutes to ensure that polyvinylpyrrolidone is uniformly dispersed in the gel network. Step 5: Add lactic acid to the reaction system obtained in Step 4, and stir and mix at 40-55℃ for 20-40 minutes to ensure that the lactic acid is evenly dispersed and combines with the gel network; Step 6: Add citric acid to the reaction system obtained in Step 5 and react at 50-70℃ for 1-2 hours to stabilize and strengthen the gel network; Step 7: Adjust the pH of the system to 5.5-6.5; Step 8: Wash, dry, pulverize, and sieve the reaction product to obtain the composite cross-linked three-dimensional cellulose gel material.

6. The preparation method according to claim 5, characterized in that, Washing the reaction products includes: first washing 2-3 times with 50% ethanol solution at a solid-liquid ratio of 1:4, and then washing 2-3 times with 90% ethanol solution at a solid-liquid ratio of 1:

3.

7. The preparation method according to claim 6, characterized in that, The washing process with ethanol is carried out in conjunction with a stirring and vibration system. The stirring speed is 10-30 rpm, and the stirring method is used in an intermittent manner, stirring for 5 minutes and letting it stand for 2 minutes in a cycle. The vibration frequency is 20-50 Hz, the amplitude is 1-3 mm, and the vibration method is used in an intermittent manner, vibrating for 3 minutes and letting it stand for 2 minutes in a cycle.

8. The preparation method according to claim 5, characterized in that, The drying in step eight is vacuum drying, and the temperature of the vacuum drying is 50-60℃.

9. The preparation method according to claim 5, characterized in that, The sieving mentioned in step eight is sieving through an 80-200 mesh sieve.

10. The use of the composite cross-linked three-dimensional cellulose gel material according to any one of claims 1 to 4, or the composite cross-linked three-dimensional cellulose gel material prepared by the method according to any one of claims 5 to 9, in the preparation of anti-glycation skin care products or antioxidant skin care products.

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