High-oil-loading pH-responsive biphase gel as well as preparation method and application thereof

Abstract

The invention discloses high-oil-loading pH-responsive biphase gel as well as a preparation method and application thereof, and belongs to the field of biological medicines and cosmetics. The gel is prepared from a long-chain alkyl grafted and modified polymer matrix and an inorganic cross-linking agent sodium borate decahydrate through ion coordination cross-linking. The preparation method comprises the following steps: reacting the component A with the component B in a solvent to obtain a hydrophobically modified polymer matrix; and mixing and cross-linking with sodium borate decahydrate in water to form gel. According to the method, the oil carrying capacity of the gel is remarkably improved, and the oil carrying capacity is larger than or equal to 20 wt%. Meanwhile, physical crosslinking points formed by alkyl hydrophobic aggregation can cooperate with boric acid ester bonds to improve the pH response performance of the gel, in an acid environment, the boric acid ester bonds are broken firstly, then the physical crosslinking points are destabilized and disintegrated, finally, a gel structure network is disintegrated, active ingredients carried in the gel are released, the lower the pH is, the faster the release is, and the gel system is endowed with the pH response characteristic.

Description

Technical Field

[0001] This invention relates to the fields of biomedicine and cosmetics, and more specifically to a high oil-loading pH-responsive biphasic gel, its preparation method, and its application. Background Technology

[0002] Biphasic gels, as functional materials capable of simultaneously and stably encapsulating both aqueous and oil phases, demonstrate significant application value in high-end cosmetics (such as serums and creams) and topical medical preparations (such as wound dressings and transdermal drug delivery systems) due to their excellent biocompatibility, unique sensory experience, and potential for co-loading hydrophilic and hydrophobic active ingredients. An ideal cosmetic or medical gel not only needs to be safe and gentle but should also efficiently carry and control the release of oil-soluble active ingredients, including vitamin E, phytosterols, and various lipid-soluble drugs, to achieve multiple benefits such as deep nourishment, antioxidant repair, or time-dependent therapeutic effects.

[0003] However, existing biphasic gels still face two interrelated core technological bottlenecks that limit their full performance and application expansion:

[0004] Firstly, the matrix is ​​highly hydrophilic, resulting in insufficient inherent oil-carrying capacity. Most current biphasic gels use hydrophilic polymer networks such as polyvinyl alcohol, sodium hyaluronate, and sodium alginate as their structural framework. While these matrices possess good hydration capabilities, their strongly hydrophilic molecular structure is inherently incompatible with the hydrophobic oil phase components, leading to limited space for the gel system to accommodate the oil phase and low loading efficiency. This "hydrophilic-hydrophobic" contradiction makes it difficult for gels to achieve a high proportion of oil phase encapsulation (typically, the oil loading is less than 10 wt%), severely restricting the effective addition of highly active oil-soluble ingredients, resulting in products with limited efficacy and failing to meet market demands for high-efficacy, multi-functional formulations.

[0005] Secondly, the release behavior is passive and simplistic, lacking intelligent responsiveness. Traditional gels rely heavily on simple diffusion mechanisms for drug or active ingredient release, with the release rate primarily driven by concentration gradients, making precise control difficult. This passive release mode cannot adapt to complex application scenarios: in cosmetics, it cannot achieve sequential release of different active ingredients to match the skin's absorption rhythm; in the medical field, it cannot respond to changes in the wound microenvironment (such as the acidic pH of infected sites) to achieve on-demand, intelligent drug release. Therefore, developing a "smart" gel capable of sensing external stimuli (such as pH changes) and adjusting its release behavior accordingly is crucial to enhancing its application value.

[0006] To address the above problems, those skilled in the art have attempted to introduce hydrophobic components through blending, physical encapsulation, and other methods. However, these methods often encounter new challenges such as uneven modification, severe phase separation, or deterioration of mechanical properties. Therefore, there is an urgent need for an innovative strategy that, starting from molecular design, can fundamentally improve the lipophilicity of the gel matrix while simultaneously endowing it with environmentally responsive properties. This strategy is crucial for preparing a new generation of biphasic gels that combine high oil-carrying capacity with intelligent release performance, and it is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0007] In view of this, the present invention provides a high oil-loading pH-responsive biphasic gel, its preparation method, and its application. This successfully increases its oil loading capacity and endows it with pH-responsive properties.

[0008] To solve the above-mentioned technical problems, this application adopts the following technical solution: The primary objective of this application is to provide: a high oil-carrying pH-responsive biphase gel, prepared by coordination and crosslinking of a modified polymer matrix and an inorganic crosslinking agent; The modified polymer matrix is ​​sodium hyaluronate or polyvinyl alcohol grafted with long-chain alkyl groups; the inorganic crosslinking agent is sodium borate decahydrate. The mass ratio of the modified polymer matrix to the inorganic crosslinking agent is 0.1-2 g: 0.01-1 g.

[0009] As a preferred technical solution, the modified polymer matrix is ​​prepared by the following method: Components A and B, along with triethylamine, were added to N-methylpyrrolidone solvent, stirred, and freeze-dried to prepare sodium hyaluronate or polyvinyl alcohol grafted with long-chain alkyl groups. Component A is one or a combination of two of sodium hyaluronate and polyvinyl alcohol; component B is one or a combination of two of 1,2-epoxytetradecane and 1,2-epoxyeicosane. As a preferred technical solution, the mass-to-volume ratio of component A to N-methylpyrrolidone solvent is 0.1-2 g: 10 mL; the mass-to-volume ratio of component B to N-methylpyrrolidone solvent is 0.1-5 g: 10 mL; and the mass-to-volume ratio of triethylamine to N-methylpyrrolidone solvent is 1 g: 10 mL.

[0010] As a preferred technical solution, the reaction temperature of the stirring reaction is 25-200℃.

[0011] Another objective of this application is to provide a method for preparing the aforementioned high oil-loaded pH-responsive biphasic gel, comprising the following steps: S1. Preparation of modified polymer matrix: Component A, component B and triethylamine are added to N-methylpyrrolidone and stirred at a temperature of 25-200℃. Under the alkaline environment provided by triethylamine, the hydroxyl groups of component A react with the epoxy functional groups of component B to obtain a mixture. The mixture is freeze-dried to remove the solvent and obtain the modified polymer matrix. S2. Gelation: The modified polymer matrix and inorganic crosslinking agent obtained in step S1 are added to water and stirred to allow the inorganic crosslinking agent to release borate ions to form dynamic and reversible borate ester bonds with the hydroxyl groups on the molecular chain of the modified polymer matrix, thereby obtaining a high oil-carrying pH-responsive biphase gel.

[0012] As a preferred technical solution, in step S1, component A is one or a combination of two of sodium hyaluronate and polyvinyl alcohol; component B is one or a combination of two of 1,2-epoxytetradecane and 1,2-epoxyeicosane. The mass-to-volume ratio of component A to N-methylpyrrolidone solvent is 0.1-2 g: 10 mL; the mass-to-volume ratio of component B to N-methylpyrrolidone solvent is 0.1-5 g: 10 mL; and the mass-to-volume ratio of triethylamine to N-methylpyrrolidone solvent is 1 g: 10 mL.

[0013] As a preferred technical solution, in step S2, the mass-to-volume ratio of the modified polymer matrix to water is 0.1-2 g: 10 mL; the mass-to-volume ratio of the inorganic crosslinking agent to water is 0.01-1 g: 10 mL; and the inorganic crosslinking agent is sodium borate decahydrate.

[0014] Another object of this application is to provide: the oil loading of the high oil loading pH-responsive biphase gel or the high oil loading pH-responsive biphase gel prepared by the method is ≥20wt%.

[0015] Another object of this application is to provide the application of the high oil-loading pH-responsive biphasic gel or the high oil-loading pH-responsive biphasic gel prepared by the method in the preparation of medical products or cosmetics.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: (1) Significantly improves oil carrying capacity and compatibility By chemically grafting hydrophobic segments containing long-chain alkyl groups (derived from component B) onto a hydrophilic polymer backbone (component A), the hydrophilic-hydrophobic balance of the gel matrix is ​​fundamentally improved. The resulting modified polymer possesses both a hydrophilic backbone and hydrophobic side chains, significantly enhancing its affinity for oily components. This increases the oil loading capacity of the gel system to a high level of 20 wt%, overcoming the bottleneck of low oil loading efficiency in traditional hydrophilic gels and broadening the loading range for oil-soluble active ingredients.

[0017] (2) Achieving both pH response and excellent adhesion of the gel Using sodium borate decahydrate as a crosslinking agent, the released borate ions form dynamically reversible borate ester bonds with the hydroxyl groups on the modified polymer matrix molecular chains. Simultaneously, the hydrophobic aggregation of alkyl groups forms physical crosslinking points, synergistically constructing a pH-sensitive three-dimensional network. This gel is structurally stable under physiological pH conditions (e.g., pH 5.5-7.0 of healthy skin), allowing it to closely adhere to irregular skin surfaces or wound shapes, achieving gapless coverage. Upon contact with an acidic microenvironment, the borate ester bonds break first, triggering the instability and disintegration of the physical crosslinking points. The gel network gradually degrades, releasing the carried active ingredients as needed, with the release rate increasing at lower pH levels. This pH-responsive characteristic precisely adapts to changes in the wound microenvironment or skin physiological rhythms, significantly improving the local retention efficiency and targeted delivery effect of the active ingredients.

[0018] (3) Constructing a stable two-phase structure The aqueous and oil phases exhibit good stability within the gel. Verified by constant temperature and humidity aging tests at 40℃ and 70% humidity, the product can be stably retained for one month under these stringent conditions, effectively ensuring the consistency of product performance throughout its shelf life.

[0019] (4) The preparation method is simple and controllable. The preparation process is clear and the conditions are mild. It can be prepared efficiently in two steps (first chemical grafting modification, then ionic crosslinking), and has good process controllability and reproducibility.

[0020] (5) It has both biocompatibility and functional expandability The selected base materials (such as sodium hyaluronate and polyvinyl alcohol) have good biocompatibility, and no toxic reagents are introduced during the modification process. Furthermore, the platform boasts strong technological compatibility, facilitating the flexible integration of different functional active ingredients in aqueous or oil phases to meet the needs of various scenarios, including moisturizing and repairing in cosmetics and sustained-release drugs in the medical field.

[0021] In summary, this application has successfully prepared a biphasic gel with both high oil loading capacity and pH response through an innovative synergistic strategy of "hydrophobic grafting modification" and "pH response". This effectively solves the two core problems of traditional biphasic gels: poor oil loading capacity and passive and single release behavior. It has outstanding application advantages in the fields of cosmetics and medical dressings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 Here is a microscope image of the biphasic gel prepared in Example 1 of this invention.

[0024] Figure 2 Here is a microscope image of the biphasic gel prepared in Example 2 of this invention.

[0025] Figure 3 Here is a microscope image of the biphasic gel prepared in Example 3 of this invention.

[0026] Figure 4 Here is a microscope image of the biphasic gel prepared in Comparative Example 1 of this invention.

[0027] Figure 5 Here is a microscope image of the biphasic gel prepared in Comparative Example 2 of this invention.

[0028] Figure 6 Here is an optical photograph of the biphasic gel prepared in Example 1 of this invention.

[0029] Figure 7 Here is an optical photograph of the biphasic gel prepared in Example 2 of this invention.

[0030] Figure 8 Example 3 of the present invention: Optical photograph of the biphase gel prepared.

[0031] Figure 9 Here is an optical photograph of the biphase gel prepared in Comparative Example 1 of this invention.

[0032] Figure 10 Here is an optical photograph of the biphase gel prepared in Comparative Example 2 of this invention.

[0033] Figure 11 The figure shows the viscosity-shear rate curve of the biphase gel in Example 1 of this invention.

[0034] Figure 12 The figure shows the viscosity-shear rate curve of the biphase gel in Example 2 of this invention.

[0035] Figure 13 The figure shows the viscosity-shear rate curve of the biphase gel in Example 3 of this invention.

[0036] Figure 14 Here is the viscosity-shear rate curve of the biphase gel in Comparative Example 1 of this invention.

[0037] Figure 15 Here is the viscosity-shear rate curve of the biphase gel in Comparative Example 2 of this invention.

[0038] Figure 16 Here is the viscosity-shear rate curve of the biphase gel in Comparative Example 4 of this invention.

[0039] Figure 17 Example 1 of the present invention: drug release curve of biphasic gel.

[0040] Figure 18 Example 2 of the present invention: drug release curve of biphasic gel.

[0041] Figure 19 Example 3 of the present invention: drug release curve of biphasic gel.

[0042] Figure 20 Here is the drug release curve of the biphasic gel in Comparative Example 1 of this invention.

[0043] Figure 21 Here is the drug release curve of the biphasic gel in Comparative Example 2 of this invention.

[0044] Figure 22 Here is an optical photograph of the biphase gel prepared in Comparative Example 3 of this invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1 A high oil-carrying pH-responsive biphase gel was prepared by coordination and crosslinking of polyvinyl alcohol grafted with long-chain alkyl groups and sodium borate decahydrate. The specific preparation process is as follows: S1. Preparation of modified polymer matrix: 0.25 g polyvinyl alcohol, 2.5 g 1,2-epoxyeicosane, and 1 g triethylamine were added to 10 mL N-methylpyrrolidone and stirred at 100 °C for 24 h to allow the hydroxyl groups of polyvinyl alcohol to react with the epoxy functional groups of 1,2-epoxyeicosane, resulting in a mixture; the mixture was freeze-dried to remove the solvent, yielding the modified polymer matrix; S2. Gelation: Take 0.5 g of the modified polymer matrix obtained in step S1 and 0.04 g of sodium borate decahydrate. To verify its oil carrying capacity, take 2.635 g of MCT oil. Add all three to 10 mL of water and stir at 30°C for 1 h. This allows the borate ions released by the sodium borate decahydrate to form dynamic and reversible borate ester bonds with the hydroxyl groups on the molecular chain of the modified polymer matrix, thus obtaining a high oil carrying capacity pH-responsive biphase gel.

[0047] Example 2 A high oil-carrying pH-responsive biphase gel was prepared by coordination and crosslinking of polyvinyl alcohol grafted with long-chain alkyl groups and sodium borate decahydrate. The specific preparation process is as follows: S1. Preparation of modified polymer matrix: 0.1 g of polyvinyl alcohol, 0.1 g of 1,2-epoxyeicosane, and 1 g of triethylamine were added to 10 mL of N-methylpyrrolidone and stirred at 25 °C for 24 h to allow the hydroxyl groups of polyvinyl alcohol to react with the epoxy functional groups of 1,2-epoxyeicosane to obtain a mixture; freeze-drying was performed to remove the solvent and obtain the modified polymer matrix; S2. Gelation: Take 0.1 g of the modified polymer matrix obtained in step S1 and 0.01 g of sodium borate decahydrate. To verify its oil carrying capacity, also take 2.5275 g of vitamin E. Add all three to 10 mL of water and stir at 30°C for 1 h. This allows the borate ions released by the sodium borate decahydrate to form dynamic and reversible borate ester bonds with the hydroxyl groups on the molecular chain of the modified polymer matrix, thus obtaining a high oil carrying capacity pH-responsive biphase gel.

[0048] Example 3 A high oil-carrying pH-responsive biphase gel was prepared by coordination and crosslinking of polyvinyl alcohol grafted with long-chain alkyl groups and sodium borate decahydrate. The specific preparation process is as follows: S1. Preparation of modified polymer matrix: 2 g of sodium hyaluronate, 5 g of 1,2-epoxytetradecane, and 1 g of triethylamine were added to 10 mL of N-methylpyrrolidone and stirred at 200 °C for 24 h to allow the hydroxyl groups of sodium hyaluronate to react with the epoxy functional groups of 1,2-epoxytetradecane to obtain a mixture; freeze-drying was performed to remove the solvent and obtain the modified polymer matrix; S2. Gelation: Take 2 g of the modified polymer matrix obtained in step S1 and 1 g of sodium borate decahydrate. To verify its oil carrying capacity, also take 3.25 g of phytosterol. Add all three to 10 mL of water and stir at 30°C for 1 h. This allows the borate ions released by the sodium borate decahydrate to form dynamic and reversible borate ester bonds with the hydroxyl groups on the molecular chain of the modified polymer matrix, thus obtaining a high oil carrying capacity pH-responsive biphase gel.

[0049] Comparative Example 1 The difference from Example 1 is that the mass of component B is 0 g. Without the addition of component B, it is impossible to graft alkyl chains onto component A; therefore, this serves as a control experiment.

[0050] Comparative Example 2 The difference from Example 1 is that component B is replaced with another substance having alkyl and epoxy groups, namely 1,2-epoxyoctane. This demonstrates that the gel can only be obtained with the aforementioned component B.

[0051] Comparative Example 3 The difference from Example 1 is that component A is replaced with another polymeric material with a large number of hydroxyl groups, namely polyethylene glycol. This demonstrates that the gel can only be obtained with the aforementioned component A.

[0052] Comparative Example 4 The difference from Example 1 is that the MCT mass is 3 g, i.e., the oil phase content is 22%, in order to determine the upper limit of oil loading in the gel of the present invention.

[0053] To verify the performance of the gels prepared in Examples 1-3 and Comparative Examples 1-4 of this application, the following experiments were conducted: The samples from Examples 1-3 and Comparative Examples 1-2 were stored in a constant temperature and humidity chamber at 40°C and 70% humidity for one month. Subsequently, their microstructure, optical morphology photographs, and rheological behavior (viscosity-shear rate) were tested. The experimental results are as follows: Figures 1-15 As shown.

[0054] Microscopic morphology characterization results (Figures 1-3) show that the oil droplets in all samples were uniformly dispersed in the initial state. After a month of wet heat aging treatment, the oil droplets in the samples of each example remained uniformly distributed, and the morphology did not change significantly. This result confirms that this type of gel has excellent stability under a high oil loading of 20 wt%. The reason for this is that the grafting modification of long-chain alkyl groups constructs hydrophobic microdomains in the gel, which can effectively contain the oil phase, thereby significantly improving the oil loading capacity of the gel. However, after the same aging treatment, the oil droplets in the samples of Comparative Examples 1-2 showed obvious aggregation, accompanied by the precipitation of the oil phase. It was no longer possible to observe the uniform dispersion of oil droplets in the gel matrix, indicating that gels without alkyl grafting or grafted with other long-chain alkyl groups are difficult to stably maintain a high oil loading state.

[0055] Optical photographic observations (Figures 6-10) show that all samples were initially pale yellow, homogeneous, creamy solids. Among them, the samples of each embodiment maintained the morphological characteristics of a pale yellow, homogeneous cream after the aforementioned hydrothermal aging treatment (Figures 6-8), further confirming their structural stability under a high oil loading of 20 wt%. In contrast, the samples of Comparative Examples 1-2 showed obvious phase separation after the same aging process, with a large amount of oil droplets agglomerated and the oil phase floating to the surface (Figures 9-10), consistent with the microscopic morphology characterization results. This again demonstrates that gels without alkyl grafts or with non-long-chain alkyl grafts cannot stably maintain a high oil loading state.

[0056] The rheological behavior of the gel also reflects its oil-carrying stability. For example... Figures 11-15 As shown, in the initial state, the viscosity of the sample decreased continuously and regularly with increasing shear rate, without random fluctuations or any abnormal points deviating from the pattern, indicating that the internal structure of the gel was uniform and homogeneous. After one month of storage in a humid and hot environment, the viscosity-shear rate curves of each embodiment were basically consistent with the initial state, further proving that each embodiment had excellent long-term stability at a high oil loading of 20wt%. In contrast, the gels of Comparative Examples 1-2 showed irregular viscosity fluctuations with changes in shear rate, indicating that their internal homogeneity had been destroyed, the oil phase had precipitated, and their oil loading stability was poor. This experiment demonstrates that the biphase gel constructed in this invention can solve the problem of low oil loading in biphase gels.

[0057] Figure 16 This indicates that when the oil loading of the gel exceeds 20%, abnormal rheological fluctuations occur, indicating internal heterogeneity. Therefore, the upper limit of the oil loading of the gel in this invention is 20%.

[0058] To verify the pH response performance of the gel, samples of Examples 1-3 and Comparative Examples 1-2 of equal volume were placed in solutions with different pH values. After soaking for 0.5 hours, the amount of drug released in the supernatant of each sample was determined using a UV spectrophotometer.

[0059] The results are as follows Figure 17-21 As shown, under different pH conditions, the drug release of the samples in each example increased significantly as the pH decreased, indicating that the gel has obvious pH-responsive characteristics. This is because after alkyl groups are grafted onto component A, the physical cross-linking points formed by the hydrophobic aggregation of alkyl groups in the gel can synergistically enhance the pH-responsive performance of the gel with the borate ester bonds. In acidic environments, the borate ester bonds break first, leading to the instability and disintegration of the physical cross-linking points, ultimately causing the gel structure network to disintegrate and releasing the active ingredient carried in the gel. The lower the pH, the faster the release, thus giving the gel system its pH-responsive characteristics. In contrast, the release amounts of samples in Comparative Examples 1-2 were basically consistent in solutions with different pH values, showing no pH dependence. Therefore, the synergistic effect of components A, B, and sodium borate decahydrate is a key structural factor in achieving pH-controlled release of the gel. Furthermore, as... Figure 22 As shown, control group 3 could not obtain a gel, and the prepared sample was in a solution state, indicating that the present invention can only obtain the gel under the condition of component A.

[0060] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high oil-loading pH-responsive biphase gel, characterized in that, It was prepared by coordination and crosslinking of a modified polymer matrix and an inorganic crosslinking agent; The modified polymer matrix is ​​sodium hyaluronate or polyvinyl alcohol grafted with long-chain alkyl groups; the inorganic crosslinking agent is sodium borate decahydrate. The mass ratio of the modified polymer matrix to the inorganic crosslinking agent is 0.1-2 g: 0.01-1 g.

2. The high oil-loading pH-responsive biphase gel according to claim 1, characterized in that, The modified polymer matrix was prepared using the following method: Components A and B, along with triethylamine, were added to N-methylpyrrolidone solvent, stirred, and freeze-dried to prepare sodium hyaluronate or polyvinyl alcohol grafted with long-chain alkyl groups. Component A is one or a combination of two of sodium hyaluronate and polyvinyl alcohol; component B is one or a combination of two of 1,2-epoxytetradecane and 1,2-epoxyeicosane.

3. The high oil-loading pH-responsive biphase gel according to claim 2, characterized in that, The mass-to-volume ratio of component A to N-methylpyrrolidone solvent is 0.1-2 g: 10 mL; the mass-to-volume ratio of component B to N-methylpyrrolidone solvent is 0.1-5 g: 10 mL; and the mass-to-volume ratio of triethylamine to N-methylpyrrolidone solvent is 1 g: 10 mL.

4. The high oil-loading pH-responsive biphase gel according to claim 2, characterized in that, The reaction temperature of the stirring reaction is 25-200℃.

5. A method for preparing a high oil-loading pH-responsive biphase gel as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of modified polymer matrix: Component A, component B and triethylamine are added to N-methylpyrrolidone and stirred at a temperature of 25-200℃. Under the alkaline environment provided by triethylamine, the hydroxyl groups of component A react with the epoxy functional groups of component B to obtain a mixture. The mixture is freeze-dried to remove the solvent and obtain the modified polymer matrix. S2. Gelation: The modified polymer matrix and inorganic crosslinking agent obtained in step S1 are added to water and stirred to allow the borate ions released by the inorganic crosslinking agent to form dynamic and reversible borate ester bonds with the hydroxyl groups on the molecular chain of the modified polymer matrix, thus obtaining a high oil-carrying pH-responsive biphase gel.

6. The preparation method according to claim 5, characterized in that, In step S1, component A is one or a combination of two of sodium hyaluronate and polyvinyl alcohol; component B is one or a combination of two of 1,2-epoxytetradecane and 1,2-epoxyeicosane. The mass-to-volume ratio of component A to N-methylpyrrolidone solvent is 0.1-2 g: 10 mL; the mass-to-volume ratio of component B to N-methylpyrrolidone solvent is 0.1-5 g: 10 mL; and the mass-to-volume ratio of triethylamine to N-methylpyrrolidone solvent is 1 g: 10 mL.

7. The preparation method according to claim 5, characterized in that, In step S2, the mass-to-volume ratio of the modified polymer matrix to water is 0.1-2 g: 10 mL; the mass-to-volume ratio of the inorganic crosslinking agent to water is 0.01-1 g: 10 mL; and the inorganic crosslinking agent is sodium borate decahydrate.

8. The high oil-loading pH-responsive biphase gel according to any one of claims 1-4 or the high oil-loading pH-responsive biphase gel prepared by the method according to any one of claims 5-7, characterized in that, The oil loading capacity of the high oil-loading pH-responsive biphasic gel is ≥20wt%.

9. The use of the high oil-loading pH-responsive biphasic gel according to any one of claims 1-4 or the high oil-loading pH-responsive biphasic gel prepared by the method according to any one of claims 5-7 in the preparation of medical products or cosmetics.

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