Composite hydrogel for medical auxiliary materials and preparation method thereof

Abstract

The invention belongs to the technical field of medical materials, and particularly relates to a composite hydrogel for medical dressings, the hydrogel is composed of carrageenan, locust bean gum, polyvinyl alcohol, polyvinylpyrrolidone, potassium chloride, diglycerol and water, and functional components such as dragon fruit powder and taurine can be selectively added. The preparation method comprises the following steps: dissolving PVA in hot water, adding mixed powder of carrageenan and locust bean gum, uniformly stirring and swelling, adding PVP, KCl, diglycerol and other functional components, heating to form uniform and clear composite sol, and cooling to obtain physical crosslinking gel with good adhesion and resilience; and inducing PVP and PVA in the gel to be further crosslinked by adopting 60Co gamma ray irradiation, so as to obtain a final product with higher mechanical strength and more stable structure. The hydrogel is high in transparency, can be tightly attached to skin or tissue, has excellent biocompatibility, moisturizing performance and structural stability, and is suitable for wound dressing.

Description

Technical Field

[0001] This invention belongs to the field of medical materials technology, specifically relating to a composite hydrogel for medical adjuvants and its preparation method. Background Technology

[0002] In wound care, medical dressings play a crucial role. An ideal high-performance wound dressing should actively promote healing, with core functions including: providing and maintaining a moist environment to accelerate epithelial regeneration; adhering closely to tissue to prevent exudate buildup and microbial invasion; possessing good mechanical flexibility to adapt to areas of body movement; and being both biosafety-resistant and easy to remove. Hydrogels, due to their high water content (typically >70%), excellent biocompatibility, and mechanical properties similar to soft tissue, are considered ideal matrix materials for achieving these functions.

[0003] Currently, common commercial hydrogel dressings are mainly based on single natural polymers (such as sodium alginate, carrageenan, and gelatin) or synthetic polymers (such as polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA)). However, single-material systems often have significant drawbacks. For example, κ-carrageenan can form a thermally reversible gel in the presence of K⁺, but its network structure is fragile, its water retention capacity is limited, and it is prone to dehydration and shrinkage after prolonged use, leading to adhesion between the dressing and the wound and causing secondary damage; locust bean gum alone has low gel strength and poor thermal stability; although synthetic polymer PVP hydrogels have excellent biocompatibility, their adhesion to moist tissues is generally insufficient, and the mechanical strength and toughness of pure PVP gels cannot simultaneously meet clinical needs.

[0004] To overcome the limitations of single materials, existing technologies mostly employ physical blending or chemical cross-linking methods for modification. While physical blending is simple to operate, the components are mainly bound by weak interactions such as hydrogen bonds, resulting in a gel network with poor stability. This network is prone to structural relaxation and performance degradation under immersion in body fluids or mechanical stress. Chemical cross-linking methods (such as using small molecule cross-linking agents like glutaraldehyde and genipin) can significantly improve mechanical properties, but residual cross-linking agents can introduce potential cytotoxicity and sensitization risks. Furthermore, the cross-linking process is difficult to control precisely, easily leading to unevenness within the gel network, affecting its swelling behavior and user comfort.

[0005] Crucially, existing hydrogel dressings struggle to strike a balance between two key clinical attributes: strong adhesion and easy removal. Insufficient adhesion can lead to dressing displacement, leaving the wound unprotected; while excessive adhesion (such as some acrylic pressure-sensitive adhesives) can easily damage newly formed epithelial tissue during removal.

[0006] Therefore, developing a composite hydrogel dressing that can be constructed using green processes, synergistically optimize adhesion, removability, mechanical strength, and biocompatibility, and is suitable for wound environments is a pressing technical problem in the field of medical materials. Summary of the Invention

[0007] This invention provides a composite hydrogel for medical dressings, its preparation method and application, which effectively solves the technical problems of poor mechanical properties, difficulty in achieving both adhesion and removability of existing single colloidal hydrogels, as well as the biosafety risks and complex process control of chemical crosslinking methods. At the same time, it provides a composite hydrogel with a uniform and stable network structure, strong adhesion, easy removal, high resilience and excellent biocompatibility.

[0008] The present invention achieves the above-mentioned objective by adopting the following technical solution: a method for preparing a composite hydrogel for medical dressings, comprising the following steps:

[0009] (1) Add polyvinyl alcohol (PVA) to water and stir and heat at 90-98 °C until PVA is completely dissolved to obtain a clear and transparent PVA solution;

[0010] (2) Add the mixed powder of carrageenan and locust bean gum to the PVA solution obtained in step (1) while stirring, and continue stirring to fully disperse and swell the gum powder to obtain a swollen suspension;

[0011] (3) Heat the swollen suspension to boiling and maintain for 3 to 8 minutes until it is completely transformed into a homogeneous, transparent, viscous gel.

[0012] (4) Cool the transparent gel obtained in step (3) to 50-60 °C, and add 20% polyvinylpyrrolidone (PVP K90) aqueous solution, potassium chloride (KCl) and diglycerides in sequence while stirring. Continue stirring at this temperature until all additives are completely dissolved to obtain a uniformly mixed gel precursor.

[0013] (5) Inject the gel precursor into a mold of a predetermined shape, cool and stand at room temperature for 20 to 40 minutes to allow it to solidify and form a stable physical cross-linked gel;

[0014] (6) The formed physical cross-linked gel is vacuum degassed and sealed in packaging. 60 Irradiation with a Co γ-ray source at a dose of 10–20 kGy induces further free radical cross-linking reactions in the PVP and PVA molecular chains within the gel, resulting in a final composite hydrogel with higher mechanical strength and a more stable network structure.

[0015] Preferably, the components in the composite hydrogel are as follows by mass percentage: PVA: 2%–3%; carrageenan: 0.5%–2%; locust bean gum: 0.2%–0.5%; PVP K90: 1%–2%; KCl: 0.02%–0.05%; diglyceride: 0.2%–0.5%; with the balance being water.

[0016] Preferably, in step (3), one or both of dragon fruit powder and taurine may be added as needed.

[0017] Preferably, the amounts of dragon fruit powder and taurine are relatively independent, and their respective mass percentages are: 0.2% to 0.5% dragon fruit powder and 0.2% to 0.5% taurine.

[0018] Preferably, the carrageenan is κ-type carrageenan, which is pre-mixed with locust bean gum in dry powder form in a certain proportion.

[0019] Preferably, in step (1), the degree of alcoholysis of the PVA is 98% to 99%, the degree of polymerization is 1700 ± 100, and the dissolution temperature is preferably 95 °C.

[0020] Preferably, in step (2), the stirring time is 10 to 20 minutes, followed by standing and swelling for 15 to 25 minutes to ensure that the adhesive powder is fully hydrated.

[0021] Preferably, in step (3), the heating method is oil bath heating, the heating temperature is controlled at 120±5 ℃, and the boiling time is preferably 5 minutes.

[0022] Preferably, in step (4), the PVP is a commercial 20% concentration aqueous solution, or it can be prepared from pure PVP. The KCl, diglycerides and functional additives (dragon fruit powder, taurine) need to be pretreated to ensure rapid dissolution and dispersion.

[0023] Preferably, in step (5), the mold is made of polytetrafluoroethylene, silicone or polypropylene, and the cooling molding time is preferably 30 minutes.

[0024] Preferably, in step (6), the 60 The preferred irradiation dose of the Co γ-ray source is 15 kGy. Before irradiation, the sealed packaged gel needs to be vacuumed for 3-5 seconds to eliminate the inhibitory effect of oxygen on free radical reactions.

[0025] A composite hydrogel prepared by the above-described method for preparing a composite hydrogel for medical dressings has strong adhesion, easy removal, good resilience and high transparency.

[0026] An application of the above-mentioned composite hydrogel in the preparation of medical dressings, specifically for use in wound dressings.

[0027] The beneficial effects of this invention are:

[0028] This invention provides a method for preparing a composite hydrogel for medical dressings, which involves optimizing the compounding of biocompatible natural polysaccharides (carrageenan, locust bean gum) with synthetic polymers (PVA, PVP), and innovatively introducing... 60 Co-γ-ray irradiation crosslinking technology. This method first constructs a physically crosslinked gel framework based on a carrageenan / locust bean gum ionic-hydrogen bond network and a PVA physical entanglement network through a heating and dissolution process. This framework already possesses certain adhesion and resilience. Subsequently, utilizing the high penetration and energy of γ-rays, free radicals are generated in situ within the gel from PVP and PVA molecular chains without the introduction of any chemical crosslinking agents, leading to intermolecular or intramolecular grafting and crosslinking reactions. This process superimposes a uniform and stable covalently crosslinked network onto the primary physical network, thus forming a unique physical-chemical interpenetrating dual network structure.

[0029] The method for preparing the composite hydrogel provided by this invention has the following outstanding advantages:

[0030] Green and safe: No small molecule chemical cross-linking agents such as glutaraldehyde are added throughout the entire process, which fundamentally eliminates the risk of toxic residues and ensures extremely high biological safety.

[0031] Synergistic performance enhancement: Natural polysaccharides provide good biocompatibility, adhesion and resilience framework; synthetic polymers PVA and PVP contribute excellent film-forming properties and mechanical enhancement potential; γ-irradiation crosslinking firmly binds the components together, simultaneously and significantly improving the adhesion and compression / stretch mechanical properties of the gel, overcoming the instability of pure physical gels.

[0032] Process advantages: The irradiation crosslinking process can be carried out at room temperature, is easy to control, and the degree of crosslinking can be precisely adjusted by the irradiation dose. It also has sterilization and disinfection functions, making it particularly suitable for the production of medical products.

[0033] Functional Integration: The addition of diglycerides as a moisturizer enhances dressing comfort; dragon fruit powder provides natural color and potential antioxidant benefits; taurine, a known skin conditioner and antioxidant, helps improve the dressing's biocompatibility and comfort. This invention successfully integrates multiple properties and functions, providing an innovative and reliable solution for developing high-end, multifunctional wound dressings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 These are images of the composite hydrogel prepared in Example 1 of the present invention. Part A shows the composite hydrogel in the mold after preparation, and Part B shows the composite hydrogel taken out of the mold and applied to the arm.

[0036] Figure 2 The image shows the composite hydrogel prepared in Example 1 of this invention adhering to a No. 3 steel ball (2.381 mm in diameter) at a 15° angle on an initial tack tester.

[0037] Figure 3 To demonstrate that the composite hydrogel prepared in Example 1 of the present invention is completely adhered to the iron plate and then peeled off without leaving any adhesive residue, part A is an image of the iron plate before the composite hydrogel is adhered, part B is an image of the iron plate when the composite hydrogel is adhered, and part C is an image of the iron plate after the composite hydrogel is peeled off.

[0038] Figure 4 The images show the composite hydrogel prepared in Example 1 of this invention cut into 1cm*1cm cubes and subjected to approximately 6.3kg of pressure without breaking. Part A shows the weight of the empty beaker and iron plate; Part B shows the beaker filled with 5L of water and the iron plate pressing on the 1cm*1cm composite hydrogel; Part C shows the composite hydrogel on the table after the beaker and iron plate have been placed down; and Part D shows the side view of the composite hydrogel after being subjected to the pressure.

[0039] Figure 5 The images show the composite hydrogels prepared in Example 1 and Comparative Example 1 of this invention. Part A shows the composite hydrogel prepared in Comparative Example 1 after being placed at room temperature for 3 days, and Part B shows the composite hydrogel prepared in Example 1 after being placed at room temperature for 6 months.

[0040] Figure 6 The images shown are of the composite hydrogels prepared in Example 1 and Comparative Example 2 of this invention before and after being placed in a 50 °C oven. Part A is the image before being placed in the oven, and Part B is the image after being placed in the oven for 30 minutes. Detailed Implementation

[0041] 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. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0042] It should be noted that, in specific embodiments of the present invention, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the use of phrases such as "comprising one" to define an element does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Those skilled in the art will understand the specific meaning of the above terms in the present invention through the specific circumstances.

[0043] Further analysis: The raw materials used in the experiments of the embodiments and comparative examples of the present invention are as follows, but are not limited to the following raw materials. The present invention only uses the following raw materials as specific examples to further illustrate the effect of the composite hydrogel for medical dressings described in the present invention.

[0044] Existing hydrogels for medical dressings still face several key bottlenecks in their clinical application: First, the gel network based on physical interactions is prone to structural relaxation under complex bodily fluid environments and mechanical friction, leading to decreased adhesion; second, the cytotoxic risks posed by the residues of chemical cross-linking agents introduced to enhance performance cannot be ignored; third, the material's adhesion, removability, resilience, mechanical strength, and biocompatibility are often mutually restrictive, making it difficult to simultaneously achieve ideal levels. Based on these technical problems, this invention provides a composite hydrogel for medical dressings, its preparation method, and its application.

[0045] The technical solution of the present invention will be described in detail below.

[0046] This invention provides a method for preparing a composite hydrogel for medical dressings, comprising the following steps:

[0047] S1, using polyvinyl alcohol (PVA) as the first matrix raw material, is heated and stirred at 90-98 °C to obtain a clear PVA solution; using a mixture of carrageenan and locust bean gum as the second gelling raw material, it is added to the PVA solution under stirring, and after dispersion and swelling, it is heated to boiling at 115-125 °C and maintained for a period of time to form a uniform and transparent primary composite gel liquid.

[0048] S2, the primary composite gel solution is cooled to 50-60 °C, and a 20% aqueous solution of polyvinylpyrrolidone (PVP K90), potassium chloride (KCl), diglycerides, and optional functional additives (such as dragon fruit powder and taurine) are added sequentially under stirring. The temperature is maintained and the mixture is stirred until completely dissolved and mixed to obtain a homogeneous gel precursor. The gel precursor is injected into a mold and allowed to stand and cool at room temperature to form a physically cross-linked gel.

[0049] S3, the physically cross-linked gel is vacuum degassed and sealed, using... 60 Irradiation treatment with a Co γ-ray source at a dose of 10–20 kGy induces the generation of free radicals and cross-linking reactions of PVA and PVP molecular chains inside the gel, thereby obtaining a final product composite hydrogel with a stable three-dimensional network structure.

[0050] In the aforementioned technical solution, based on the thermally reversible gelation properties of carrageenan in the presence of potassium ions (K⁺) and its synergistic effect with locust bean gum, a physical gel network framework mainly composed of ionic crosslinking and hydrogen bonding was first constructed through a thermal process. The addition of PVA further enhanced the toughness of this physical network through molecular chain entanglement. Subsequently, using... 60 Co-γ-ray irradiation, a green physical method, initiates the generation of free radicals at the active sites of PVA and PVP within the gel in situ without the need for any chemical cross-linking agents, leading to intermolecular grafting and covalent cross-linking. This process superimposes a uniform and stable chemical cross-linking network onto the original physical network, forming a unique physical-chemical interpenetrating network structure. This structure fundamentally enhances the integrity of the gel, enabling it to maintain high water content and biocompatibility while achieving excellent adhesion, easy removal, high resilience, significant mechanical strength, and shape stability. The composite hydrogel prepared by this invention can adhere closely and comfortably to human skin or wounds, effectively maintaining a moist healing environment, and is easy to remove, making it suitable as a high-end wound dressing.

[0051] To ensure that the gel has suitable initial viscosity and film-forming properties, the mass concentration of the PVA aqueous solution is 2% to 3%, and the dissolution temperature is preferably 95 °C.

[0052] To obtain optimal gel strength and elasticity, and to ensure full integration of functional additives, the mixing temperature of the gel precursor in step S2 should be controlled at 50–60 °C, preferably 55 °C.

[0053] In order to achieve smooth injection and demolding of the gel liquid at room temperature, the static cooling time of the gel precursor after injection into the mold is controlled at 20 to 40 minutes, preferably 30 minutes.

[0054] To obtain a stable and non-dense cross-linked network, thereby balancing adhesion and resilience, the 60 The irradiation dose of the Co gamma-ray source needs to be strictly controlled between 10 kGy and 20 kGy. A dose below this range may lead to insufficient cross-linking, inadequate network strength, and insufficient resilience; a dose that is too high may cause polymer chain degradation or an overly dense network, affecting its flexibility and adhesion. The preferred irradiation dose is 15 kGy.

[0055] To prevent oxygen from quenching free radicals during the irradiation crosslinking process and to ensure efficient crosslinking reaction, vacuum degassing and sealing of the packaging containing the physical crosslinking gel before irradiation is a crucial step. The vacuum level should be controlled between -0.08 MPa and -0.1 MPa.

[0056] To impart additional functionality to the hydrogel to improve patient comfort or aid wound healing, finely pulverized functional ingredients can be added in step S2. For example, the dragon fruit powder, added at 0.2%–0.5% of the total gel mass, not only provides natural color but also contains betalains, which may have antioxidant properties. Taurine, added at 0.2%–0.5% of the total gel mass, is a known skin conditioning agent and antioxidant, contributing to improved biocompatibility and comfort of the dressing. All additives must be ensured to completely dissolve and uniformly disperse within the gel network at 60 °C.

[0057] The invention will now be described in detail through the following embodiments and comparative examples.

[0058] Example 1

[0059] A method for preparing a composite hydrogel for medical dressings includes the following steps:

[0060] S1, weigh 2.5 g of polyvinyl alcohol (PVA, degree of alcoholysis 98%–99%, degree of polymerization 1700±100), add to 88.1 g of deionized water, and magnetically stir in a 95 ℃ oil bath for 2 hours until completely dissolved to obtain a clear and transparent PVA solution. Pre-mix 1.0 g of κ-carrageenan and 0.3 g of locust bean gum evenly, and slowly add to the PVA solution under high-speed stirring, continuing to stir for 30 minutes, and allowing to stand for swelling for 20 minutes. Then transfer the suspension to a 120 ℃ oil bath, heat to a gentle boil and maintain for 5 minutes to obtain a homogeneous, transparent, viscous gel.

[0061] S2, remove the above viscous gel solution and allow it to cool naturally to 55 °C. While stirring at a constant temperature, add sequentially 7.5 g of a 20% PVP K90 aqueous solution (containing 1.5 g of PVP solid and 6.0 g of water), 0.03 g of potassium chloride (KCl), 0.3 g of diglyceride, and 0.3 g of taurine. Maintain a 55 °C water bath and continue stirring for 1.5 hours until all additives are completely dissolved, resulting in a homogeneous and transparent gel precursor.

[0062] S3. The obtained gel precursor was allowed to stand to degas and was injected into a smooth polytetrafluoroethylene flat mold (size: 10cm×10cm×0.2cm). It was then placed horizontally at room temperature of 25 ℃ for 30 minutes to cool and solidify into a self-supporting physically cross-linked gel sheet.

[0063] S4. Place the gel sheet in a medical aluminum foil composite packaging bag, vacuum-pack it to -0.09 MPa using a vacuum packaging machine, and immediately heat-seal it. Place the sealed sample in... 60 The product was irradiated in a Co gamma-ray field with a total absorbed dose of 15 kGy. After irradiation, the final composite hydrogel product was obtained and labeled Gel-1.

[0064] Example 2

[0065] A method for preparing a composite hydrogel for medical dressings includes the following steps:

[0066] S1: Weigh 3.0 g PVA and add it to 84.4 g deionized water, then dissolve at 95 ℃. Add 1.5 g κ-carrageenan and 0.4 g locust bean gum (dry mixed) to the solution, stir, let stand, and then heat in an oil bath at 120 ℃ for 5 minutes until it boils gently to obtain a viscous gel solution.

[0067] S2, cool the viscous gel to 55 ℃, and add 10.0 g of 20% PVP K90 aqueous solution (containing 2.0 g of PVP solid and 8.0 g of water), 0.04 g of KCl, 0.4 g of diglyceride and 0.4 g of dragon fruit powder in sequence, and stir for 1.5 hours until completely dissolved and homogeneous.

[0068] S3. Pour the gel liquid into the mold and let it stand at room temperature for 30 minutes to solidify.

[0069] S4, after vacuum sealing, uses 60 Irradiated with Co gamma rays at a dose of 18 kGy. The resulting product was labeled Gel-2.

[0070] Example 3

[0071] A method for preparing a composite hydrogel for medical dressings includes the following steps:

[0072] S1: Weigh 2.2 g PVA and add it to 88.5 g deionized water, then dissolve at 95 ℃. Add 0.8 g κ-carrageenan and 0.25 g locust bean gum (dry mixed), stir, let stand, and then heat in an oil bath at 120 ℃ for 5 minutes until a viscous gel is obtained.

[0073] S2, cool the viscous gel solution to 55 ℃, and add 7.5 g of 20% PVP K90 aqueous solution (containing 1.5 g of PVP solid and 6.0 g of water), 0.025 g of KCl, 0.25 g of diglyceride, 0.25 g of dragon fruit powder and 0.25 g of taurine in sequence, and stir for 1.5 hours until completely dissolved and homogeneous.

[0074] S3. Pour the gel liquid into the mold and let it stand at room temperature for 30 minutes to solidify.

[0075] S4, after vacuum sealing, uses 60 Irradiated with Co gamma rays at a dose of 10 kGy. The resulting product was labeled Gel-3.

[0076] Example 4

[0077] A method for preparing a composite hydrogel for medical dressings:

[0078] The formulation was adjusted to increase the proportion of carrageenan to enhance initial gel strength. Specifically: PVA 2.8 g, κ-carrageenan 1.8 g, locust bean gum 0.3 g, 20% PVP K90 aqueous solution 9.0 g (containing 1.8 g PVP solids and 7.2 g water), KCl 0.04 g, diglyceride 0.4 g, taurine 0.2 g, and deionized water to a final volume of 100 g. The preparation steps were the same as in Example 1, with an irradiation dose of 15 kGy. The resulting product was labeled Gel-4.

[0079] Example 5

[0080] A method for preparing a composite hydrogel for medical dressings:

[0081] The formula was adjusted to focus on moisturizing and a soft touch. Specifically: PVA 2.5 g, κ-carrageenan 1.0 g, locust bean gum 0.5 g, 20% PVP K90 aqueous solution 6.0 g (containing 1.2 g PVP solids and 4.8 g water), KCl 0.03 g, diglyceride 0.5 g, dragon fruit powder 0.2 g, taurine 0.2 g, and deionized water to a final volume of 100 g. The preparation steps were the same as in Example 1, with an irradiation dose of 12 kGy. The resulting product was labeled Gel-5.

[0082] Comparative Example 1

[0083] The same formula and steps S1 to S3 as in Example 1 are used, but step S4 is omitted. 60 Co γ-ray irradiation crosslinking treatment was used to prepare physically crosslinked gel sheets, which were then directly used as samples. The resulting samples were labeled CG-1 and used to compare and verify the key role of irradiation crosslinking.

[0084] Comparative Example 2

[0085] The same formulation and steps S1 to S4 as in Example 1 were used, but PVA was not added, and the amount of deionized water was adjusted accordingly to maintain a consistent total mass. The resulting sample was labeled CG-2 and used to compare and verify the key role of PVA.

[0086] To further illustrate the effects of the present invention, the composite hydrogel prepared by the present invention was subjected to the following performance tests and evaluations:

[0087] 1. Appearance, transparency, and formability

[0088] like Figure 1 As shown, the composite hydrogel (Gel-1) prepared in Example 1 of this invention presents a uniform and complete sheet shape in the mold, with a smooth surface and no obvious bubbles or defects. After being removed from the mold, the gel sheet exhibits good self-support and flexibility, easily adhering to human skin (such as the arm) and fitting tightly, demonstrating its excellent molding process applicability and initial adhesion performance. More importantly, the hydrogel exhibits extremely high transparency, allowing for direct and clear observation of the wound healing status and exudation without removal when used as a wound dressing. This facilitates non-invasive clinical monitoring and effectively avoids secondary damage caused by wound examination.

[0089] 2. Adhesion performance test

[0090] Adhesion is one of the key performance characteristics of medical dressings. Qualitative evaluation is performed through initial tack testing: such as... Figure 2As shown, when the Gel-1 sample is placed on the initial tack tester and the angle of the initial tack tester is kept at 15°, its surface can firmly adhere to a standard No. 3 steel ball (diameter 2.381 mm). This indicates that the hydrogel has excellent immediate adhesion (initial tack) and can quickly form an effective bond with the contact surface, which is beneficial for the initial fixation of the dressing.

[0091] In addition, the gel removal performance was investigated. For example... Figure 3 As shown, the Gel-1 sample was completely adhered to the surface of a clean iron plate and then removed. The results showed that the gel could be completely removed, and no obvious gel residue was observed on the iron plate surface. This demonstrates that the hydrogel provided by this invention achieves both strong adhesion and easy removal, avoiding the risk of residual gel causing damage to new tissue or skin during removal, thus balancing a key contradiction in the clinical use of dressings.

[0092] 3. Mechanical strength and durability testing

[0093] Hydrogels need to possess sufficient mechanical strength to withstand external forces during use. Load-bearing tests were conducted on the Gel-1 samples: (e.g., ...) Figure 4 As shown, the sample was cut into 1cm × 1cm cubes and placed on a flat table. A weight of approximately 6.3kg (approximately 1.3kg of iron plate, an empty beaker, and 5L of water inside the beaker) was applied on top. After the pressure was applied, the hydrogel cubes deformed to some extent (as can be seen from the residual watermarks), but they completely recovered after the pressure was removed. They did not crack or permanently collapse, and no gel residue remained on the table. This demonstrates that its network structure has excellent compressive strength and resilience, sufficient to withstand the pressure and friction generated by daily activities, and can provide effective physical protection for the wound.

[0094] 4. Sterility test

[0095] To verify the crucial role of irradiation crosslinking in the stability of the gel network, the long-term performance of the irradiated crosslinked sample of Example 1 (Gel-1) was compared with that of the unirradiated Comparative Example 1 sample (CG-1). Figure 5 As shown, CG-1 samples exhibited significant mold growth after only 3 days at room temperature. In contrast, Gel-1 samples maintained their integrity, elasticity, and transparency after 6 months at room temperature, without any mold growth. This comparative result fully demonstrates... 60 Co-γ ray irradiation not only induces the formation of covalent cross-linked networks, enhancing the structural stability of the hydrogel, but also effectively sterilizes the hydrogel, avoiding the need to add additional chemical antibacterial agents during production. This demonstrates the product's excellent long-term storage stability and hygienic safety.

[0096] 5. Verification of heat resistance and component functions

[0097] To investigate the performance stability of the gel under warm and hot conditions and to verify the role of the PVA component, a heat resistance test was designed. For example... Figure 6 As shown, the Gel-1 sample and the PVA-free comparative sample CG-2 were placed simultaneously in a 50 °C oven. After 30 minutes, it was observed that the CG-2 sample underwent severe melting, deformation, and flow, completely losing its gel morphology. In contrast, the Gel-1 sample, under the same conditions, maintained its intact solid gel morphology and dimensional stability. This result clearly demonstrates that the presence of the PVA component and its cross-linked network with PVP formed by irradiation jointly endow the hydrogel with excellent thermal stability, ensuring its reliability for use in environments below 50 °C.

[0098] in conclusion

[0099] The above series of test results and accompanying figures visually demonstrate the superior comprehensive performance of the composite hydrogel provided by this invention. Tests show that the hydrogel (Gel-1) of this invention possesses excellent immediate adhesion, firmly adhering to a standard steel ball; it leaves no residue after removal, achieving a balance between strong adhesion and easy removal; it recovers its original shape after withstanding approximately 6.3 kg of pressure, exhibiting good resilience; irradiated samples remain stable after being placed at room temperature for 6 months, and the irradiation process also has a sterilization effect, eliminating the need for additional antibacterial agents. In summary, this invention, through a unique physical-chemical dual-network construction strategy, provides a composite hydrogel with superior comprehensive performance. This hydrogel fully meets the high standards of safety, effectiveness, and user experience required for high-end wound dressings, functional skin patches, and other medical dressings, and has broad clinical application prospects.

[0100] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite hydrogel for medical dressings, characterized in that, Includes the following steps: (1) Add polyvinyl alcohol to water and stir and heat at 90-98 °C until PVA is completely dissolved to obtain a clear and transparent solution; (2) Add the mixed powder of carrageenan and locust bean gum to the solution obtained in step (1) while stirring until the gum powder is fully dispersed and swollen to obtain a swollen suspension; (3) Heat the swollen suspension to boiling and maintain for 3 to 8 minutes until it is completely transformed into a homogeneous, transparent, viscous gel. (4) Cool the transparent gel obtained in step (3) to 50-60 °C, and add 20% polyvinylpyrrolidone aqueous solution, potassium chloride and diglyceride in sequence while stirring. Continue stirring at this temperature until all additives are completely dissolved to obtain a uniformly mixed gel precursor. (5) The gel precursor is injected into a mold of a predetermined shape and cooled at room temperature for 20 to 40 minutes to form a physically cross-linked gel. (6) The physically cross-linked gel obtained in step (5) is vacuum degassed and sealed in packaging. 60 The composite hydrogel was obtained by irradiation treatment with a Co γ-ray source at a dose of 10–20 kGy to obtain a cross-linked enhanced hydrogel.

2. The method for preparing the composite hydrogel for medical dressings according to claim 1, characterized in that, The components, by mass percentage, are: PVA 2%–3%, carrageenan 0.5%–2%, locust bean gum 0.2%–0.5%, 20% polyvinylpyrrolidone aqueous solution 1%–2%, KCl 0.02%–0.05%, diglyceride 0.2%–0.5%, and the balance being water.

3. The method for preparing the composite hydrogel for medical dressings according to claim 2, characterized in that, In step (4), one or both of dragon fruit powder and taurine may be added as needed.

4. The method for preparing the composite hydrogel for medical dressings according to claim 3, characterized in that, The amounts of dragon fruit powder and taurine are relatively independent, and their respective mass percentages are: dragon fruit powder 0.2% to 0.5% and taurine 0.2% to 0.5%.

5. The method for preparing the composite hydrogel for medical dressings according to claim 1, characterized in that, In step (1), the degree of alcoholysis of PVA is 98%–99%, the degree of polymerization is 1700±100, and the dissolution temperature is 95 ℃.

6. The method for preparing the composite hydrogel for medical dressings according to claim 1, characterized in that, In step (2), the stirring time is 10 to 20 minutes, and the mixture is allowed to stand and swell for 15 to 25 minutes.

7. The method for preparing the composite hydrogel for medical dressings according to claim 1, characterized in that, In step (3), an oil bath is used for heating at a temperature of 120±5 ℃, and boiling is maintained for 5 minutes.

8. The method for preparing the composite hydrogel for medical dressings according to claim 1, characterized in that, The mold used in step (5) is made of polytetrafluoroethylene, silicone or polypropylene.

9. A composite hydrogel prepared by the method for preparing a composite hydrogel for medical dressings according to any one of claims 1 to 8, characterized in that, It has strong adhesion, is easy to remove, has good resilience and high transparency.

10. An application of the composite hydrogel according to claim 9 in the preparation of medical dressings, specifically for use in wound dressings.

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