A temperature-sensitive hydrogel carrier, a preparation method and application thereof

Abstract

The application discloses a temperature-sensitive hydrogel carrier, a preparation method and application thereof, relates to the technical field of biomedical materials, and comprises the following steps: S1, dissolving poloxamer and a solubilizing modifier in a PBS buffer solution with pH 7.4, performing first radiation crosslinking, and obtaining product A; S2, adding a biological adhesion material containing a catechol group into the product A, adjusting the pH value of the mixed system, and then performing second radiation crosslinking to obtain the temperature-sensitive hydrogel carrier; and the ionizing radiation of the first radiation crosslinking and the second radiation crosslinking is gamma rays or electron beams. The two-step ionizing radiation crosslinking method is adopted, the poloxamer network, the solubilizing modifier and the biological adhesion material containing the catechol group are tightly combined through chemical bonds, the mechanical strength and the structural stability of the gel are improved on the basis of retaining the temperature response characteristics of the temperature-sensitive hydrogel, and the burst release phenomenon after carrying functional components is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, and in particular to a thermosensitive hydrogel carrier, its preparation method, and its application. Background Technology

[0002] Thermosensitive hydrogels, due to their temperature-responsive sol-gel phase transition properties, have become an important research direction in biomedical fields such as drug delivery, tissue engineering, and wound dressings. Among them, poloxamer-based thermosensitive hydrogels are one of the core matrix materials in this field. These gels are in a fluid sol state at low temperatures, facilitating injection and coating operations. At body temperature, they can rapidly transform into a gel state, enabling local retention of functional components and possessing the potential for long-term local delivery, thus attracting widespread attention in the biomedical field.

[0003] However, existing poloxamer thermosensitive hydrogels still have many technical defects that need to be addressed in practical applications, and these defects directly limit their clinical application: First, the gel's mechanical strength is insufficient and the stability of its three-dimensional network structure is poor, making it prone to burst release after loading functional components, thus failing to achieve controlled sustained release of functional components and seriously affecting the accuracy and efficacy of local drug delivery; Second, it has poor wet adhesion, making it difficult to remain in the moist physiological environment of the human body, such as oral mucosa and moist wounds, and it is prone to detachment, failing to achieve local long-term delivery of functional components; Third, it has poor drug compatibility, only having a certain loading capacity for water-soluble functional components, and its loading efficiency for lipid-soluble functional components is extremely low, making it difficult to simultaneously and efficiently load both water-soluble and lipid-soluble active ingredients, thus limiting its application scenarios.

[0004] To address the aforementioned shortcomings, existing technologies have attempted relevant improvements. For example, Chinese invention patent CN111603441A discloses "An amphiphilic polyamino acid copolymer / poloxam thermosensitive hydrogel and its preparation method." This method introduces a synthetically produced amphiphilic polyamino acid copolymer into poloxamer and utilizes the intermolecular physical interactions between the copolymer's amide bonds, carboxyl groups, and other active groups and poloxamer to regulate the gel's phase transition behavior and three-dimensional network structure. This improves to some extent the problem of low phase transition temperature caused by concentration dependence in traditional poloxamer gels, while also slightly optimizing the gel's swelling and carrying capacity. However, this type of modification method is essentially still a physical blending and structural regulation method. The formation of its gel network relies on intermolecular physical interactions rather than chemical bonds. Therefore, it cannot solve the technical defects of existing poloxamer thermosensitive hydrogels, such as insufficient gel strength, poor wet adhesion, and poor drug loading compatibility. Moreover, due to the instability of physical interactions, the modified gel is prone to network structure relaxation and sudden release of internal functional components under long-term storage or complex application environments (such as temperature fluctuations and immersion in human body fluids). Its structural stability and delivery controllability still cannot meet the requirements of clinical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a temperature-sensitive hydrogel carrier, its preparation method, and its application, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a temperature-sensitive hydrogel carrier, comprising the following steps: S1: Poloxamer and a solubilizing modifier were dissolved in a PBS buffer solution at pH 7.4 and subjected to the first radiation crosslinking to obtain product A; S2: Add a bioadhesive material containing catechol groups to product A, adjust the pH of the mixture, and then perform a second radiation crosslinking to obtain the thermosensitive hydrogel carrier. The ionizing radiation used for both the first and second radiation crosslinking was gamma rays or electron beams.

[0007] Preferably, the poloxamer is selected from one or more of P407, P188, P338, and P237.

[0008] Preferably, the solubilizing modifier comprises an amphiphilic polymer and / or a hydrophilic polymer; the amphiphilic polymer is selected from one or more of stearyl alcohol polyether, lauryl alcohol polyether, and cetyl alcohol polyether; the hydrophilic polymer is selected from one or more of sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid polymers, cellulose polymers, polyethylene oxide, carboxymethyl chitosan, and gelatin.

[0009] Preferably, the bioadhesive material containing catechol groups is selected from mussel adhesive proteins or their biomimetic polypeptides.

[0010] Preferably, in step S1, the amount of poloxamer added is 16-26 wt%, and the amount of the solubilizing modifier added is 1-8 wt% by mass percentage; in step S2, the amount of the bioadhesive material containing catechol groups added is 0.2-4 wt%.

[0011] Preferably, in step S1, the radiation dose for the first radiation crosslinking is 10-15 kGy; in step S2, the radiation dose for the second radiation crosslinking is 3-10 kGy.

[0012] Preferably, in step S2, the pH value of the mixed system is adjusted to 7.5-9.0 using 1M NaOH solution; in step S1, the first radiation crosslinking is carried out under oxygen-isolated conditions; in step S2, the second radiation crosslinking is carried out under controlled oxygen-containing conditions, which are nitrogen-oxygen mixed gas atmospheres containing 0.1%-5% volume fraction of oxygen introduced into the mixed system.

[0013] Preferably, in step S1, the amount of poloxamer added is 18-22 wt%, and the amount of the solubilizing modifier added is 2-6.5 wt% by mass percentage; in step S2, the amount of the bioadhesive material containing catechol groups added is 0.2-2 wt%. In step S1, the radiation dose for the first radiation crosslinking is 10-13 kGy; in step S2, the radiation dose for the second radiation crosslinking is 5-8 kGy, and the volume fraction of oxygen in the nitrogen-oxygen mixture is 2%. The gelation temperature of the prepared thermosensitive hydrogel carrier is 19℃-32℃.

[0014] A thermosensitive hydrogel carrier is prepared by a method for preparing thermosensitive hydrogel carriers. The thermosensitive hydrogel carrier is formed by chemical cross-linking of a poloxamer network, a solubilizing modifier, and a bioadhesive material containing catechol groups. The gelation temperature is 19℃-32℃.

[0015] An application of a thermosensitive hydrogel carrier, which is used in the fields of biomedicine, local drug delivery, and tissue engineering.

[0016] The technical effects and advantages of this invention are as follows: (1) The present invention adopts a two-step ionizing radiation crosslinking method to make the poloxamer network, solubilizing modifier and bioadhesive material containing catechol group tightly bonded by chemical bonds. While retaining the temperature response characteristics of thermosensitive hydrogel, the mechanical strength and structural stability of the gel are improved. The gelation temperature of the prepared hydrogel carrier can be controlled between 19℃ and 32℃, which is adapted to the human body temperature to achieve rapid phase change of sol-gel. Moreover, the gel strength is improved at 37℃ and the degradation time is extended, which effectively avoids the burst release phenomenon after carrying functional components, and realizes the stable, controllable and long-term release of functional components, solving the core problem of poor controlled release effect of existing poloxamer hydrogels. (2) This invention introduces mussel adhesive protein containing catechol groups or its biomimetic polypeptide as a bioadhesive material. With the help of the biomimetic adhesion mechanism of catechol groups, the hydrogel carrier has excellent adhesion in the moist physiological environment of the human body, such as oral mucosa and moist wounds, and does not have the problem of easy detachment. The wet disintegration time of the gel is extended, which can realize the controllable residence and disintegration of the carrier in the wet environment, effectively prolonging the local sustained release period of the functional components, and solving the technical defects of existing poloxamer gels with poor wet adhesion and inability to achieve local long-term delivery. (3) By selecting amphiphilic polymers or hydrophilic polymers as solubilizing modifiers, this invention can achieve efficient encapsulation of lipid-soluble functional components and water-soluble functional components respectively, and can also load water-soluble and lipid-soluble mixed functional components at the same time, effectively solving the problem of poor drug compatibility of existing poloxamer gels and only suitable for water-soluble components; and the stable cross-linking network constructed by this invention has a high effective encapsulation rate of functional components, which can avoid the release of functional components. After 50 cycles of high and low temperature at 0℃ / 37℃, the hydrogel carrying functional components still maintains good temperature response and gel strength, and has excellent phase change stability, which can be adapted to the stable loading of various functional components such as borneol, vitamin E, chlorhexidine gluconate, and ginsenosides. (4) This invention avoids the toxic residue of chemical reagents by using gamma rays or electron beams for ionizing radiation crosslinking. The hydrogel carrier prepared by the invention has no obvious cytotoxicity and has good biocompatibility, which meets the safety requirements of biomedical materials in clinical applications. (5) The two-step ionizing radiation crosslinking process parameters of the present invention are independently adjustable. The radiation dose and reaction atmosphere of the first and second steps can be controlled separately. The ratio range of each raw material is wide. The composition of the raw materials can be flexibly adjusted according to the actual application requirements to control the temperature sensitivity, adhesion, carrying capacity and other properties of the gel. The preparation process does not require complicated equipment, and the operation is simple and efficient. At the same time, the hydrogel carrier obtained has excellent storage stability, is easy to transport and store, and has the industrial basis for large-scale production. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a comparison chart of the rheological test results of the thermosensitive hydrogel in Example 1 and Comparative Example 1 of the present invention; Figure 2 These are degradation test images of the thermosensitive hydrogel carrier in Example 1 and Comparative Example 1 of the present invention; Figure 3 This is a schematic diagram of the disintegration experiment of the thermosensitive hydrogel carrier of the present invention immersed in PBS buffer solution at 37°C. Figure 4 Cell compatibility test of the thermosensitive hydrogel carrier in Example 1 and Comparative Example 1 of the present invention; Figure 5 These are comparative photographs showing the salicylic acid-loaded thermosensitive hydrogels prepared in Example 5 and Comparative Example 4 of the present invention at 10°C and 37°C, respectively. Figure 6 The rheological test results of the salicylic acid-loaded thermosensitive hydrogels in Example 5 and Comparative Examples 2-4 of the present invention are shown below. Figure 7 The degradation time test graphs of the salicylic acid-loaded thermosensitive hydrogels in Example 5 and Comparative Examples 2-4 of the present invention are shown. Figure 8 The graphs show the release behavior of salicylic acid by the thermosensitive hydrogel in Example 5 and Comparative Examples 2-4. Figure 9 These are photographs of the gel state of the thermosensitive hydrogels carrying functional components in Examples 13-15 of the present invention after 50 high and low temperature cycles (0℃ / 37℃). Detailed Implementation

[0018] 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.

[0019] Example 1: Preparation of blank thermosensitive hydrogel carrier by a two-step radiation method S1: Poloxamer P407 (2.0 g, 20 wt%) and stearyl alcohol polyether-20 (0.4 g, 4 wt%) were weighed and dissolved in 6.3 g PBS buffer solution (pH 7.4, 4 °C). The solution was magnetically stirred until completely dissolved, then transferred to a glass bottle, sealed, and purged with nitrogen for 30 minutes to remove oxygen. The solution was then subjected to a 12 kGy radiation dose using an electron beam at room temperature. Product A was obtained after irradiation.

[0020] S2: Mussel adhesive protein (0.2 g, 2 wt%) was dissolved in 1.1 g of pre-cooled PBS buffer solution (4 °C). After dissolution, it was added to product A and stirred to disperse it evenly. The pH of the mixture was adjusted to 7.5 with 1 M NaOH solution. The mixture was transferred to a new container and a nitrogen-oxygen mixture containing 2% oxygen (volume fraction) was introduced for 10 minutes. A second electron beam irradiation was then performed at a dose of 7 kGy. The final blank thermosensitive hydrogel carrier was obtained.

[0021] Comparative Example 1: Physical blending method corresponding to Example 1 (physical blending control) To verify the effect of two-step radiation crosslinking on the structure and properties of the gel network, this comparative example was set up. Poloxamer P407 (2.0 g, 20 wt%), stearyl alcohol polyether-20 (0.4 g, 4 wt%), and mussel adhesive protein (0.2 g, 2 wt%), in the same proportions as in Example 1, were weighed and dissolved in 7.4 g of PBS buffer solution (pH 7.4). The solution was stirred at room temperature until homogeneous, yielding a blank physically thermosensitive hydrogel carrier. The difference between this comparative example and Example 1 is that no radiation crosslinking treatment was performed; the components were mixed solely through physical stirring.

[0022] Comparison of effects: The phase transition temperature and gel strength of the material were tested using a rheometer. The results are as follows: Figure 1 As shown, the phase transition temperatures of Example 1 and Comparative Example 1 are 20.4℃ and 19.1℃, respectively, indicating that the radiation-modified poloxamer still exhibits good temperature responsiveness. Meanwhile, at 37℃, the gel strengths of Example 1 and Comparative Example 1 are 341 Pa and 77 Pa, respectively. The gel strength of Example 1 is approximately 4.4 times higher than that of Comparative Example 1, demonstrating that the chemical crosslinking network is significantly superior to the physical blending system.

[0023] The gel degradation experiment results showed that the degradation time of Comparative Example 1 was 1.7 h, while that of Example 1 was 3.2 h, proving that radiation crosslinking significantly improved the structural stability of the material.

[0024] Wet adhesion tests showed that the gel disintegration time of Example 1 was 175 min, while that of Comparative Example 1 was 55 min. During the experiment, the thermosensitive hydrogel of Example 1 did not detach from the pigskin, demonstrating that the chemically cross-linked mussel protein network endows the material with excellent wet adhesion properties.

[0025] Examples 2-4: Preparation of thermosensitive hydrogel carriers with different radiation types and doses The raw material composition in Examples 2-4 is exactly the same as that in Example 1. The radiation type and radiation dose are shown in Table 1. Table 1. Types of radiation and radiation doses used in Examples 2-4

[0026] Comparison of effects: The phase transition temperature and gel strength test results of the thermosensitive hydrogel supports prepared in Examples 2-4 are listed in Table 2. The phase transition temperatures of Examples 2-4 were 20.9℃, 20.4℃, and 20.3℃, respectively, indicating that different radiation types and doses have little effect on the temperature responsiveness of poloxamer. Meanwhile, at 37℃, the gel strengths of Examples 2-4 were 351 Pa, 304 Pa, and 325 Pa, respectively, indicating that different radiation types have no significant effect on gel strength. While higher or lower radiation doses may reduce gel strength to some extent, the gel strength remains above 300 Pa. Compared to Comparative Example 1, the cross-linked structure generated after stepwise irradiation with a specific dose significantly improves gel strength.

[0027] The gel degradation experiment results showed that the degradation times of Examples 2-4 were 3.2h, 2.9h and 3.0h, respectively, which were comparable to the degradation time of Example 1, and the material structure stability remained basically stable.

[0028] Wet adhesion tests showed that the gel disintegration times for Examples 2-4 were 177 min, 165 min, and 173 min, respectively. During the experiments, the thermosensitive hydrogels of Examples 2-4 did not detach from the pigskin, demonstrating that the materials exhibit excellent wet adhesion properties under different radiation types and corresponding radiation dose ranges.

[0029] Table 2. Data on phase transition temperature, gel strength, gel degradation time, and wet adhesion time of Examples 2-4

[0030] Example 5: Preparation of a salicylic acid-loaded thermosensitive hydrogel using a two-step radiation method S1: Weigh poloxamer P407 (2.0 g, 20 wt%) and stearyl alcohol polyether-20 (0.2 g, 2 wt%), dissolve them in 6.3 g PBS buffer solution (pH 7.4, 4 °C), stir magnetically until completely dissolved, then transfer to a glass bottle, seal, and purge with nitrogen for 30 minutes to remove oxygen. Perform electron beam irradiation at a dose of 12 kGy at room temperature. Product A is obtained after irradiation.

[0031] S2: Mussel adhesive protein (0.2 g, 2 wt%) was dissolved in 1.1 g of pre-cooled PBS buffer solution (4 °C). After dissolution, it was added to product A and stirred to disperse it evenly. The pH of the mixture was adjusted to 7.5 with 1 M NaOH solution. The mixture was transferred to a new container and a nitrogen-oxygen mixture containing 2% oxygen (volume fraction) was introduced for 10 minutes. A second electron beam irradiation was then performed at a dose of 7 kGy. The final thermosensitive hydrogel carrier was obtained.

[0032] S3: Dissolve 10 mg of salicylic acid and stearyl alcohol polyether-20 (0.2 g, 2 wt%) at 50 °C to form a homogeneous solution, add it to the thermosensitive hydrogel carrier obtained in step S2, stir for 2 min, and then sonicate for 5 min at a frequency of 20 kHz to obtain the thermosensitive hydrogel loaded with salicylic acid.

[0033] Comparative Example 2: One-step radiation method corresponding to Example 5 (radiation process comparison) To verify the necessity of stepwise crosslinking in the two-step radiation process, this comparative example was set up. Poloxamer P407 (2.0 g, 20 wt%), stearyl alcohol polyether-20 (0.2 g, 2 wt%), and mussel adhesive protein (0.2 g, 2 wt%), in the same proportions as in Example 5, were weighed and dissolved in 7.4 g PBS buffer solution (pH 7.4). After sealing, nitrogen gas was purged for 30 minutes to remove oxygen, followed by electron beam irradiation. The total radiation dose was 19 kGy (i.e., the sum of the two radiation doses in Example 5), completing the crosslinking in one step. 10 mg of salicylic acid was mixed with 0.2 g of stearyl alcohol polyether-20 and added to the resulting carrier. The mixture was stirred for 2 min, followed by ultrasonic treatment for 5 min at a frequency of 20 kHz, to obtain a salicylic acid-loaded thermosensitive hydrogel.

[0034] Comparative Example 3: Default second radiation corresponding to Example 5 (adhesion network missing control) To verify the necessity of constructing the mussel protein adhesion network through a second radiation crosslinking, this comparative example was set up. Poloxamer P407 (2.0 g, 20 wt%) and stearyl alcohol polyether-20 (0.2 g, 2 wt%) were weighed and dissolved in 6.3 g of PBS buffer solution (pH 7.4). After sealing, nitrogen gas was purged for 30 minutes to remove oxygen, followed by electron beam irradiation at a dose of 12 kGy (same as the first irradiation in Example 5), yielding product A. At 4°C, mussel adhesion protein (0.2 g, 2 wt%) was dissolved evenly in 1.1 g of PBS buffer solution and then added to product A and stirred until homogeneous (i.e., without a second irradiation). 10 mg of salicylic acid was mixed with stearyl alcohol polyether-20 (0.2 g, 2 wt%) and added to the resulting carrier. The mixture was stirred for 2 min and then sonicated for 5 min at a frequency of 20 kHz to obtain a temperature-sensitive hydrogel loaded with salicylic acid.

[0035] Comparative Example 4: Physical blending method corresponding to Example 5 (drug loading method comparison) To verify the advantages of the two-step radiation method in drug loading performance, this comparative example was set up. Poloxamer P407 (2.0 g, 20 wt%), stearyl alcohol polyether-20 (0.2 g, 2 wt%), and mussel adhesive protein (0.2 g, 2 wt%), in the same proportions as in Example 5, were weighed and dissolved in 7.4 g PBS buffer solution (pH 7.4). The solution was stirred until homogeneous to obtain a thermosensitive hydrogel carrier. 10 mg of salicylic acid was mixed with stearyl alcohol polyether-20 (0.2 g, 2 wt%) and added to the thermosensitive hydrogel carrier. The mixture was then stirred for 2 min and sonicated for 5 min at a frequency of 20 kHz to obtain a thermosensitive hydrogel loaded with salicylic acid.

[0036] Comparison of effects: Figure 5 The gel states of Example 5 and Comparative Example 4 after loading salicylic acid are shown. Comparative Example 4 showed significant drug precipitation and turbidity, indicating that the salicylic acid loaded in the physically blended system failed to achieve stable binding with the gel network. Example 5 produced a clear and transparent gel, demonstrating that radiation modification can significantly improve the gel's ability to hold lipid-soluble components.

[0037] The results of the basic performance tests are shown in Table 3. Example 5 maintained the phase transition point (20.1℃), high gel strength (377Pa), long gel degradation time (3.4h), and wet disintegration time (187min). Due to differences in radiation conditions, the hydrogels prepared in Comparative Examples 2-3 did not form a dense three-dimensional network structure, and therefore their gel strength and wet adhesion were relatively poor.

[0038] Table 3. Disintegration times of salicylic acid-loaded thermosensitive hydrogels in Example 5 and Comparative Examples 2-4

[0039] Table 4 lists the effective encapsulation rates of salicylic acid by the thermosensitive hydrogels in Example 5 and Comparative Examples 2-4. The effective encapsulation rates of Comparative Examples 2-4 were significantly lower than those of Example 5, indicating that the uniform and stable cross-linked network constructed by two-step ionizing radiation can significantly improve the gel's ability to hold functional components.

[0040] Table 4. Effective encapsulation efficiency (%) of salicylic acid by the thermosensitive hydrogel in Example 5 and Comparative Examples 2-4

[0041] Figure 8The release curves shown reflect the release characteristics of salicylic acid in different examples and comparative examples. Example 5 exhibits a clear sustained-release behavior, with stable drug release and no burst release. In contrast, Comparative Example 4 (physical mixture system) shows severe initial burst release of the drug. Comparative Examples 2 and 3, due to their irregular and incomplete gel radiation crosslinking network structure, still exhibit some degree of burst release of salicylic acid, resulting in poor sustained-release effects.

[0042] Examples 6-8: Preparation of hydrogels formulated with different concentrations and types of poloxamer Based on the above technical solutions, temperature-sensitive hydrogels that meet the beneficial effects of this invention can be prepared by adjusting the concentration of poloxamer and the compounding conditions of different types. The specific raw material ratios of Examples 6-8 are shown in Table 5, and the preparation methods are the same as those in Example 5.

[0043] Table 5. Thermosensitive hydrogel formulations for salicylic acid-loaded hydrogels in Examples 6-8.

[0044] Table 6 lists the phase transition temperature and gel strength data of the thermosensitive hydrogels of Examples 6-8. The results show that Examples 6-8 all have good temperature responsiveness and gel strength. The phase transition temperature of this series of thermosensitive hydrogels can be controllably adjusted within the range of 19-32℃.

[0045] Table 6. Phase transition temperature and gel strength data of salicylic acid-loaded thermosensitive hydrogels in Examples 6-8.

[0046] Examples 9-10: Optimization of stearyl alcohol polyether concentration and verification of critical values Examples 9 and 10 show variations in the concentration of stearyl alcohol polyether, corresponding to adjustments in the carrying capacity of the thermosensitive hydrogel for lipid-soluble functional components. The preparation method is the same as in Example 5, and the specific raw material ratios are shown in Table 7.

[0047] Table 7 Formulations of Examples 9-10

[0048] Comparative Example 5: Extremely low solubilizer concentrations corresponding to Examples 9-10 (drug loading threshold control) To verify the minimum effective concentration of the solubilizing modifier in carrying lipophilic components, this comparative example was set up. Poloxamer P407 (2.0 g, 20 wt%), stearyl alcohol polyether-20 (0.08 g, 0.8 wt%), and mussel protein (0.2 g, 2 wt%), along with 7.72 g of PBS buffer solution and 0.01 g of salicylic acid, were weighed. The preparation method was the same as in Example 5.

[0049] Comparison of effects: Table 8 lists the effective encapsulation efficiency of salicylic acid in the thermosensitive hydrogels of Examples 5, 9, 10 and Comparative Example 5. The results show that the effective encapsulation efficiency of salicylic acid in Examples 5, 9, and 10 is positively correlated with the amount of stearyl alcohol polyether added to the system. As shown in Comparative Example 5, when the stearyl alcohol polyether content is less than 1 wt%, it is insufficient to fully load the added 1 wt% lipid-soluble drug, resulting in salicylic acid precipitation. When the content exceeds 4 wt% (Examples 5 and 10), the increase in encapsulation efficiency tends to level off, indicating that the carrying capacity of the hydrophobic microdomains in the gel is close to saturation.

[0050] Table 8. Effective encapsulation efficiency (%) of salicylic acid by the thermosensitive hydrogels of Examples 5, 9, 10 and Comparative Example 5.

[0051] Examples 11-12: Regulation of Mussel Protein Content on Wet Adhesion Examples 11 and 12 show different amounts of mussel protein in the system, used to adjust the wet adhesion of the thermosensitive hydrogel. The preparation method is the same as in Example 5, and the specific raw material ratios are shown in Table 9.

[0052] Table 9 Formulations of Examples 11-12

[0053] Table 10 lists the phase transition temperature and gel strength data of Examples 11-12. The results show that Examples 11-12 all have good temperature response and gel strength. Moreover, with the increase of mussel protein content, the wet disintegration time is correspondingly extended (142 min for Example 11 and 210 min for Example 12), and the adhesion performance is enhanced.

[0054] Table 10 shows the phase transition temperature and gel strength data of the salicylic acid-loaded thermosensitive hydrogels in Examples 11-12.

[0055]

[0056] Examples 13-15: Verification of Broadband Loading Capability The aforementioned thermosensitive hydrogel carrier possesses broad-spectrum loading capacity and can be applied in biomedicine, local drug delivery, and tissue engineering. Examples 13-15 were designed to support different functional components, including lipid-soluble functional components such as borneol and vitamin E, and water-soluble functional components such as chlorhexidine gluconate and ginsenosides. The proportions of each raw material are shown in Table 11, and the preparation method is the same as in Example 5.

[0057] Table 11. Formulations of thermosensitive hydrogels in Examples 13-15

[0058] Thermosensitive hydrogels carrying functional components prepared in Examples 13-15 were tested for their thermosensitive phase transition stability, and the test results are shown in Table 12. The results show that the thermosensitive hydrogels in Examples 13-15 maintained good temperature responsiveness and gel strength after multiple high and low temperature cycling treatments, proving that the thermosensitive hydrogel carrier of the present invention has a broad-spectrum carrying capacity and can achieve stable loading of functional components within the gel system.

[0059] Table 12 shows the changes in gel phase transition temperature and gel strength of the thermosensitive hydrogels in Examples 13-15 before and after 50 high-low temperature cycles.

[0060] Figure 9 The diagrams show the gel phase transition of the thermosensitive hydrogels carrying functional components in Examples 13-15 after 50 high and low temperature cycles, confirming that the carrier has good temperature cycling stability.

[0061] Detailed explanation of performance testing methods Phase transition temperature (Tgel) determination: Temperature scanning tests were performed using a rheometer to conduct dynamic rheological analysis of the hydrogel. The storage modulus G' can be obtained through dynamic rheological analysis. The temperature at which the storage modulus increases sharply with temperature is the phase transition temperature of the gel.

[0062] Gel strength determination: This test measures the thermosensitive hydrogel's ability to maintain its three-dimensional network structure and resist external force damage at 37°C, expressed as storage modulus (G'). This property was measured using a rheometer to determine the storage modulus (G') of the thermosensitive hydrogel at 37°C.

[0063] Gel degradation experiment: After staining the hydrogel with toluidine blue, 0.3g of the gel was placed in a transparent glass bottle, and 2ml of PBS buffer solution (pH 7.4) was added. The bottle was incubated at 37℃, and the PBS buffer solution (pH 7.4) was replaced every 1h. The sample was weighed to examine the degradation of the gel and the degradation time was recorded.

[0064] Wet bioadhesion simulation experiment: Using pigskin from Bama miniature pigs with a thickness of 0.8-1 mm to simulate skin, 0.3 g of gel was in situ formed into cylinders with a diameter of 1.0 mm, utilizing the gel's thermosensitive properties. The gel adhered to the pigskin surface through its adhesive properties. The pigskin with the gel was then immersed in PBS buffer solution (pH 7.4) at 37°C, and the disintegration time of the gel under wet conditions was examined to evaluate the wet adhesion performance of the material.

[0065] Cell compatibility test: Thermosensitive hydrogel was immersed in culture medium at 0.1 g / mL and extracted at 37℃ for 24 h to obtain the extract. L929 cells were seeded in 96-well plates, and after culturing for 24 h with the extract added, the OD value was measured at 490 nm using the MTT assay. Branched polyethyleneimine (PEI25K, Sigma-Aldrich) with a molecular weight of 25 kDa was used as a positive control to determine the cell compatibility of the thermosensitive hydrogel.

[0066] Effective encapsulation efficiency (EE%) determination of functional components: The effective encapsulation efficiency is used to characterize the encapsulation ability of the carrier material for functional components. Specifically, it represents the proportion of functional components remaining in the thermosensitive hydrogel after excluding those that rapidly dissipate within 20 minutes of initial contact with the release medium. In the examples and comparative examples, salicylic acid was used as a representative lipid-soluble substance and loaded into a thermosensitive hydrogel carrier to prepare a salicylic acid-loaded thermosensitive hydrogel. The amount of salicylic acid was measured using a UV spectrophotometer.

[0067] Release curve determination of functional components: In a simulated physiological environment (PBS, 37℃), the cumulative release rate of salicylic acid was continuously monitored at multiple time points to characterize the sustained-release behavior of the material and to plot the release curve. The salicylic acid content was measured using a UV spectrophotometer, and the release curve of the temperature-sensitive hydrogel carrying salicylic acid over time was plotted.

[0068] Thermosensitive phase transition stability test: After subjecting the thermosensitive hydrogel carrying the functional components to 50 high and low temperature cycles (0℃ / 37℃), the gel phase transition and gel state were observed.

[0069] In summary, this invention constructs a thermosensitive hydrogel carrier with a chemically cross-linked dual-network structure, which significantly reduces the burst release rate of drugs while improving the mechanical strength, wet adhesion, and drug loading capacity of the gel. It has broad application prospects in the fields of local drug delivery, tissue engineering, and cosmetics.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a temperature-sensitive hydrogel carrier, characterized in that, Includes the following steps: S1: Poloxamer and a solubilizing modifier were dissolved in a PBS buffer solution at pH 7.4 and subjected to the first radiation crosslinking to obtain product A; S2: Add a bioadhesive material containing catechol groups to product A, adjust the pH of the mixture, and then perform a second radiation crosslinking to obtain the thermosensitive hydrogel carrier. The ionizing radiation used for both the first and second radiation crosslinking was gamma rays or electron beams.

2. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, The poloxamer is selected from one or more of P407, P188, P338, and P237.

3. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, The solubilizing modifier includes amphiphilic polymers and / or hydrophilic polymers; The amphiphilic polymer is selected from one or more of stearyl alcohol polyether, lauryl alcohol polyether, and cetyl alcohol polyether; The hydrophilic polymer is selected from one or more of sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid polymers, cellulose polymers, polyethylene oxide, carboxymethyl chitosan, and gelatin.

4. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, The bioadhesive material containing catechol groups is selected from mussel adhesive proteins or their biomimetic polypeptides.

5. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, In step S1, by mass percentage, the amount of poloxamer added is 16-26 wt%, and the amount of the solubilizing modifier added is 1-8 wt%. In step S2, the amount of the bioadhesive material containing catechol groups added is 0.2-4 wt%.

6. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, In step S1, the radiation dose for the first radiation crosslinking is 10-15 kGy; In step S2, the radiation dose for the second radiation crosslinking is 3-10 kGy.

7. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, In step S2, the pH of the mixed system is adjusted to 7.5-9.0 using 1M NaOH solution; In step S1, the first radiation crosslinking is carried out under oxygen-isolated conditions; in step S2, the second radiation crosslinking is carried out under controlled oxygen-containing conditions, which are nitrogen-oxygen mixed gas atmospheres containing 0.1% to 5% volume fraction of oxygen introduced into the mixed system.

8. The method for preparing a thermosensitive hydrogel carrier according to claim 1, characterized in that, In step S1, by mass percentage, the amount of poloxamer added is 18-22 wt%, and the amount of the solubilizing modifier added is 2-6.5 wt%. In step S2, the amount of the bioadhesive material containing catechol groups added is 0.2-2 wt%. In step S1, the radiation dose for the first radiation crosslinking is 10-13 kGy; In step S2, the radiation dose for the second radiation crosslinking is 5-8 kGy, and the volume fraction of oxygen in the nitrogen-oxygen mixture is 2%. The gelation temperature of the prepared thermosensitive hydrogel carrier is 19℃-32℃.

9. A temperature-sensitive hydrogel carrier, characterized in that, The thermosensitive hydrogel carrier is prepared by any one of claims 1-8, wherein the thermosensitive hydrogel carrier is formed by chemical cross-linking of a poloxamer network, a solubilizing modifier, and a bioadhesive material containing catechol groups, and the gelation temperature is 19℃-32℃.

10. An application of the thermosensitive hydrogel carrier as described in claim 9, characterized in that, The thermosensitive hydrogel carrier can be applied to the fields of biomedicine, local drug delivery, and tissue engineering.

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