Composite hydrogel dressing based on gradient freeze thawing as well as preparation method and application of composite hydrogel dressing
The composite hydrogel dressing prepared by the gradient freeze-thaw method solves the problems of adhesion, antibacterial properties and healing of traditional dressings, achieves efficient wound healing support, has excellent mechanical properties and biocompatibility, and is suitable for the repair of a variety of wounds.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JILIN UNIVERSITY
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-01
AI Technical Summary
Traditional wound dressings have problems such as easy adhesion to new tissue, limited antibacterial ability, and lack of ability to promote wound healing. Furthermore, hydrogels prepared by chemical cross-linking methods pose a risk of biotoxicity.
Composite hydrogels were prepared using a gradient freeze-thaw method. A ternary composite precursor solution was formed by mixing polyvinyl alcohol, polyvinylpyrrolidone, and sericin solution, followed by gradient freeze-thaw treatment, and finally impregnated with potassium guaiacol sulfonate solution to form a loaded composite hydrogel dressing.
A multifunctional hydrogel dressing with excellent mechanical properties, good biocompatibility, adhesion, drug release ability and antibacterial ability was prepared, which reduces secondary damage to newly formed tissues, adapts to different wound microenvironments, shortens the preparation cycle, and is simple to produce on a large scale.
Smart Images
Figure CN121944207A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biomedical materials technology, specifically to a composite hydrogel dressing based on gradient freeze-thaw cycles, its preparation method, and its application. Background Technology
[0002] Traditional wound dressings, such as gauze, suffer from problems such as easy adhesion to newly formed tissue, causing secondary damage, limited antibacterial ability, and lack of wound healing promotion. Hydrogels, however, have attracted significant attention in the wound dressing field due to their excellent biocompatibility, hydrophilicity, and moisturizing properties. Polyvinyl alcohol (PVA) is commonly used as a hydrogel substrate, exhibiting good biocompatibility and a water content similar to human tissue. However, single-particle PVA hydrogels suffer from poor mechanical strength and insufficient adhesion. Polyvinylpyrrolidone (PVP), with its excellent solubility and pore-forming ability, can improve the swelling properties and drug release capacity of hydrogel dressings. Sericin, as a natural biomolecule, is rich in amino acids and serine active sites, which can further improve the adhesion and mechanical properties of hydrogels, promote cell proliferation and differentiation, and enhance the bioactivity of hydrogel dressings. Potassium guaiacol sulfonate, a commonly used antitussive and expectorant drug in clinical practice, has recently been found to have certain antibacterial and anti-inflammatory effects.
[0003] Hydrogel wound dressings are often prepared using chemical cross-linking methods, but the introduced cross-linking agents pose a risk of residual biotoxicity, potentially causing inflammatory reactions or cell death, severely limiting their application in wound dressings. In contrast, hydrogels prepared using physical cross-linking methods do not require the introduction of small-molecule cross-linking agents, making them green, safe, and non-toxic.
[0004] Therefore, developing a multifunctional hydrogel wound dressing that combines excellent mechanical properties, good biocompatibility, adhesion, drug release capability, and antibacterial ability is of great clinical significance. Summary of the Invention
[0005] The purpose of this invention is to provide a composite hydrogel dressing based on gradient freeze-thaw cycles, 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:
[0007] A method for preparing a composite hydrogel dressing based on gradient freeze-thaw cycles includes the following steps:
[0008] A binary composite precursor solution was obtained by mixing a polyvinyl alcohol solution and a polyvinylpyrrolidone solution.
[0009] Sericin powder was mixed with a binary composite precursor solution to obtain a ternary composite precursor solution.
[0010] The ternary composite precursor solution was injected into a mold and prepared by gradient freeze-thaw method to obtain ternary composite hydrogel.
[0011] A ternary composite hydrogel was impregnated in a potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate.
[0012] Furthermore, the mass concentration of the polyvinyl alcohol solution is 15-25 wt%; the mass concentration of the polyvinylpyrrolidone solution is 15-25 wt%; and the volume ratio of the polyvinyl alcohol solution to the polyvinylpyrrolidone solution is 7-3:3-7.
[0013] Furthermore, the method for preparing the sericin powder is as follows: sericin is extracted from silkworm cocoons using a hot alkali degumming method, then freeze-dried and ground to obtain sericin powder.
[0014] Furthermore, the preparation method of the sericin protein powder specifically includes the following steps:
[0015] Several silkworm cocoons were cut into pieces, added to Na2CO3 solution and boiled for extraction, and then filtered while hot to obtain sericin extract.
[0016] The sericin extract was centrifuged to remove flocculent impurities, then mixed evenly with Tris-HCl buffer and dialyzed in deionized water to obtain a sericin protein source solution.
[0017] The original solution of sericin was freeze-dried under vacuum and then ground to obtain sericin powder.
[0018] Furthermore, the step of mixing the sericin powder with the binary composite precursor solution specifically includes: adding the sericin powder to the binary composite precursor solution, stirring at 35-45°C, then naturally cooling to room temperature, and degassing under a vacuum of 0.07-0.09 MPa.
[0019] Furthermore, the mass-to-volume ratio of the sericin powder to the binary composite precursor solution is (3-7) g: 100 mL.
[0020] Furthermore, the gradient freeze-thaw method specifically includes the following steps:
[0021] Gradient freezing: The first stage is to cool from room temperature to 3-5℃ and maintain the temperature for 1-2 hours; the second stage is to cool to -25~-15℃ and maintain the temperature for 2-4 hours; the third stage is to cool to -55~-45℃ and maintain the temperature for 1-3 hours.
[0022] Thawing process: After the gradient freezing is completed, place it at room temperature for static thawing for 4-6 hours to complete the gradient freeze-thaw preparation.
[0023] Furthermore, the method for preparing the potassium guaiacol sulfonate solution is as follows: potassium guaiacol sulfonate powder is dissolved in deionized water to obtain potassium guaiacol sulfonate solution; the mass-volume ratio of potassium guaiacol sulfonate powder to deionized water is (0.5-1.5) g: 100 mL.
[0024] Another object of the present invention is to provide a composite hydrogel dressing prepared by the above preparation method.
[0025] Another object of the present invention is to provide the application of the above-mentioned composite hydrogel dressing in the preparation of wound healing drugs.
[0026] The present invention provides a method for preparing a composite hydrogel dressing based on gradient freeze-thaw cycles. This method can produce a multifunctional composite hydrogel dressing that possesses excellent mechanical properties, good biocompatibility, adhesion, drug release capacity, and antibacterial ability. This composite hydrogel dressing can be used for wound healing. Compared with existing technologies, the present invention has the following advantages:
[0027] 1. This invention induces multiple hydrogen bond physical crosslinking through freeze-thaw cycles at different temperature gradients, which can prepare composite hydrogel dressings with both excellent mechanical properties and adhesiveness.
[0028] 2. This invention achieves a one-time freeze-thaw molding process through temperature control using a gradient freeze-thaw method. Compared with the ordinary freeze-thaw method, it significantly shortens the preparation cycle and forms a gradient porous structure with good stability and non-collapse of pores, making it suitable for different wound microenvironments.
[0029] 3. This invention prepares a ternary composite hydrogel dressing by gradient freeze-thaw method. The surface layer is highly cross-linked to resist external impact, while the interior is low cross-linked, highly flexible, and resistant to tensile fracture. It fits irregular wounds while reducing secondary damage to newly formed tissues.
[0030] 4. The sericin used in this invention is a natural bioactive macromolecule with inherent anti-inflammatory and wound-healing activities, while also synergistically enhancing the tensile strength and toughness of hydrogels.
[0031] 5. This invention achieves a synergistic effect of multiple components including polyvinyl alcohol, polyvinylpyrrolidone, sericin, and potassium guaiacol sulfonate. Polyvinyl alcohol serves as the main matrix material to construct a physical cross-linked network; polyvinylpyrrolidone enhances its hydrophilicity and adhesion, improving its swelling capacity and porosity; sericin imparts biocompatibility, promotes cell proliferation and wound healing through anti-inflammatory effects, and simultaneously improves its mechanical properties; potassium guaiacol sulfonate provides broad-spectrum antibacterial activity and reduces redness and swelling, resulting in a synergistic effect of multiple components.
[0032] 6. The preparation method used in this invention is simple, time-saving, requires low-end instruments, has low cost, is easy to implement, and can be mass-produced.
[0033] 7. The composite hydrogel dressing prepared by this invention has excellent performance and reasonable structure, meeting the needs of most clinical applications such as wound healing and wound repair. Attached Figure Description
[0034] Figure 1 This is a schematic flowchart illustrating the preparation method of the composite hydrogel dressing based on gradient freeze-thaw provided in an embodiment of the present invention.
[0035] Figure 2 The Fourier transform infrared spectra of the composite hydrogel dressings prepared in Examples 1-3 of this invention are shown.
[0036] Figure 3 This is a scanning electron microscope image of the composite hydrogel dressing prepared in Example 1 of the present invention.
[0037] Figure 4 The stress-strain curves are obtained from the tensile test of the composite hydrogel dressings prepared in Examples 1-3 of this invention.
[0038] Figure 5 The rheological properties of the composite hydrogel dressings prepared in Examples 1-3 of this invention are shown in the diagram.
[0039] Figure 6 This is a diagram showing the adhesion of the composite hydrogel dressing prepared in Example 1 of the present invention to different substrates.
[0040] Figure 7 The diagram shows the antibacterial properties of the composite hydrogel dressings prepared in Example 1 and Comparative Example 1 of this invention.
[0041] Figure 8 This is a cell compatibility diagram of the composite hydrogel dressing prepared in Example 1 of the present invention.
[0042] Figure 9 This is a comparison diagram of the blood compatibility of the composite hydrogel dressings prepared in Examples 1-3 of the present invention and Comparative Example 1. Detailed Implementation
[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0044] In one embodiment of the present invention, a composite hydrogel dressing based on gradient freeze-thaw is provided, the preparation method of which includes the following steps:
[0045] S1. Polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) are dissolved in deionized water to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution respectively; then the polyvinyl alcohol solution and polyvinylpyrrolidone solution are mixed to obtain PVA / PVP binary composite precursor solution;
[0046] S2. Add the sericin powder to the binary composite precursor solution, stir at 35-45℃, then let it cool naturally to room temperature, and degas under a vacuum of 0.07-0.09MPa to obtain the PVA / PVP / sericin ternary composite precursor solution.
[0047] S3. PVA / PVP / seric fibroin ternary composite precursor solution was injected into a mold and prepared by gradient freeze-thaw method to obtain PVA / PVP / seric fibroin ternary composite hydrogel.
[0048] S4. The PVA / PVP / sericin ternary composite hydrogel is impregnated in potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate.
[0049] In a preferred embodiment of the present invention, the mass concentration of the polyvinyl alcohol solution is 15-25 wt%; the mass concentration of the polyvinylpyrrolidone solution is 15-25 wt%; and the volume ratio of the polyvinyl alcohol solution to the polyvinylpyrrolidone solution is 7-3:3-7.
[0050] In a preferred embodiment of the present invention, the method for preparing sericin powder is as follows: sericin is extracted from silkworm cocoons using a hot alkaline degumming method, then freeze-dried and ground to obtain sericin powder. Specifically, the method includes the following steps: cutting several silkworm cocoons into fragments, adding 0.05-0.15M Na2CO3 solution for boiling and extraction, and filtering while hot to obtain sericin extract; centrifuging the sericin extract to remove flocculent impurities, then mixing it with 0.5-1.5M Tris-HCl buffer at a volume ratio of (3-5):1 in deionized water for dialyzing to obtain sericin stock solution; and then freeze-drying the sericin stock solution under vacuum and grinding to obtain sericin powder.
[0051] In a preferred embodiment of the present invention, the mass-to-volume ratio of sericin powder to binary composite precursor solution is (3-7) g: 100 mL.
[0052] In a preferred embodiment of the present invention, the gradient freeze-thaw method specifically includes the following steps:
[0053] Gradient freezing: The first stage is to cool from room temperature to 3-5℃ and maintain the temperature for 1-2 hours; the second stage is to cool to -25~-15℃ and maintain the temperature for 2-4 hours; the third stage is to cool to -55~-45℃ and maintain the temperature for 1-3 hours.
[0054] Thawing process: After the gradient freezing is completed, place it at room temperature for static thawing for 4-6 hours to complete the gradient freeze-thaw preparation.
[0055] In a preferred embodiment of the present invention, the method for preparing the potassium guaiacol sulfonate solution is as follows: potassium guaiacol sulfonate powder is dissolved in deionized water to obtain potassium guaiacol sulfonate solution; the mass-volume ratio of potassium guaiacol sulfonate powder to deionized water is (0.5-1.5) g: 100 mL.
[0056] In this embodiment of the invention, a ternary composite hydrogel was successfully prepared in a single freeze-thaw cycle by controlling different temperature gradients. Compared to the conventional freeze-thaw cycle method, this method reduces the preparation cycle while creating a gradient porous structure that adapts to the microenvironment required by different wounds, achieving the necessary breathability and absorption of tissue exudate. Gradual freezing at different temperatures enhances pore formation and prevents collapse, ensuring high porosity and structural stability of the resulting composite hydrogel dressing. The composite hydrogel dressing prepared in this embodiment of the invention has a high degree of surface cross-linking and high mechanical strength, capable of withstanding external friction and impact, while preventing accidental detachment and providing a continuous physical barrier for the wound. Furthermore, the internal cross-linking degree of this composite hydrogel dressing is relatively low, resulting in good flexibility and allowing it to closely adhere to irregular wound surfaces, reducing secondary damage to newly formed tissue.
[0057] This invention employs a synergistic approach using PVA, PVP, and sericin as three components. Under specific ratios, the ternary system exhibits optimal synergistic effects during a gradient freeze-thaw process. Freezing and thawing at different gradient temperatures forms multiple hydrogen bonds, resulting in a composite hydrogel dressing with excellent mechanical properties and adhesion. These superior mechanical properties and adhesion endow the material with high tensile strength and toughness, making it resistant to breakage, firmly adhering to irregular skin wounds, maintaining dynamic adhesion, and providing a reliable physical barrier. The components in this invention interact and function differently in the hydrogel wound dressing: PVA, as the main matrix material, constructs a three-dimensional network structure. Containing numerous hydroxyl groups, it forms a physical cross-linked network through gradient freeze-thaw, imparting high moisture retention to the wound dressing and maintaining a moist microenvironment. PVP, as an auxiliary matrix material, improves the hydrophilicity, adhesion, and biocompatibility of the hydrogel. The pyrrolidone groups in its molecular chain exhibit strong hydrophilicity, increasing the swelling rate and water retention capacity of the wound dressing. Its film-forming properties enhance the adhesion between the dressing and the wound. The hydrogel exhibits excellent adhesion and maximizes the absorption of tissue exudate. Sericin, a bioactive macromolecule, endows the hydrogel with anti-inflammatory properties and promotes cell proliferation, accelerating wound healing. Simultaneously, the introduction of sericin provides both structural support and bioactivity, further enhancing its mechanical properties and enabling it to resist external friction and impact during the healing process. Potassium guaiacol sulfonate, a functional small-molecule antibacterial agent, endows the hydrogel with antibacterial and wound-healing activity, disrupting bacterial cell membrane integrity and inhibiting bacterial respiration to achieve a broad-spectrum antibacterial effect. It also inhibits the release of inflammatory factors, reducing local redness and swelling. This multi-effect synergistic mechanism of different components provides new insights into the preparation of wound dressings and wound healing.
[0058] Example 1: As Figure 1 As shown, this embodiment provides a composite hydrogel dressing A1P1S based on gradient freeze-thaw cycles, the preparation method of which includes the following steps:
[0059] S1. Dissolve 10g of polyvinyl alcohol (PVA) and 10g of polyvinylpyrrolidone (PVP) in 40g of deionized water, and heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 5mL of polyvinyl alcohol solution and 5mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution;
[0060] S2. Cut several silkworm cocoons into pieces, rinse with deionized water to remove surface dust, take 20g of the cleaned silkworm cocoon pieces, and add 200mL of 0.1M solution. The sericin extract was extracted by boiling and stirring in Na2CO3 solution at 100℃ for 1 hour, and then filtered while hot. The sericin extract was centrifuged at 10000 rpm for 15 minutes at low temperature to remove flocculent impurities. Then, it was mixed with 1M Tris-HCl buffer at a volume ratio of 4:1 and dialyzed in deionized water for 48 hours to obtain a relatively pure sericin protein stock solution. Next, the sericin protein stock solution was freeze-dried in vacuum at -80℃ for 3 days and ground to obtain a pure light yellow sericin protein powder. 0.5 g of sericin protein powder was added to 10 mL of the above PVA / PVP binary composite precursor solution and stirred in a water bath at 40℃ for 30 minutes. Then, it was naturally cooled to room temperature and transferred to a vacuum degassing chamber for degassing at a vacuum degree of 0.08 MPa for 40 minutes to obtain a PVA / PVP / serice protein ternary composite precursor solution.
[0061] S3. Inject the above PVA / PVP / sericin ternary composite precursor solution into the mold, control the liquid level to ensure uniform spreading of the solution without overflow, and begin the gradient freeze-thaw preparation: First, cool from room temperature to 4℃ and maintain the temperature for 1.5h to complete the first stage of cooling induction and preliminary pre-nucleation; Second, cool from 4℃ to -20℃ and maintain the temperature for 3h to promote crystal nucleation and growth; Third, transfer to a cold trap and cool to -50℃ and maintain the temperature for 2h to strengthen molecular chain cross-linking and pore structure formation; After the gradient freezing is completed, remove the mold and place it at room temperature for 5h to thaw, completing the gradient freeze-thaw preparation. Take out the hydrogel sample, rinse the surface with deionized water 3 times to remove surface impurities, and obtain the PVA / PVP / sericin ternary composite hydrogel.
[0062] S4. Dissolve 0.1g of potassium guaiacol sulfonate powder in 10mL of deionized water to obtain a potassium guaiacol sulfonate solution; then, immerse the above PVA / PVP / sericin ternary composite hydrogel in the potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate, denoted as A1P1S.
[0063] Example 2: This example provides a composite hydrogel dressing A7P3S based on gradient freeze-thaw. The preparation method of this dressing differs from that of Example 1 only in step S1, while the other steps are the same.
[0064] S1: Dissolve 10g of polyvinyl alcohol (PVA) and 10g of polyvinylpyrrolidone (PVP) in 40g of deionized water, heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 7mL of polyvinyl alcohol solution and 3mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution.
[0065] Example 3: This example provides a composite hydrogel dressing A3P7S based on gradient freeze-thaw. The preparation method of this dressing differs from that of Example 1 only in step S1, while the other steps are the same.
[0066] S1: Dissolve 10g of polyvinyl alcohol (PVA) and 10g of polyvinylpyrrolidone (PVP) in 40g of deionized water, heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 3mL of polyvinyl alcohol solution and 7mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution.
[0067] Example 4: This example provides a composite hydrogel dressing based on gradient freeze-thaw cycles, the preparation method of which includes the following steps:
[0068] S1: Dissolve 7.5g of polyvinyl alcohol (PVA) and 7.5g of polyvinylpyrrolidone (PVP) in 42.5g of deionized water, heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 4mL of polyvinyl alcohol solution and 6mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution;
[0069] S2. Cut several silkworm cocoons into pieces, rinse with deionized water to remove surface dust, take 15g of the cleaned silkworm cocoon pieces, and add 200mL of 0.05M solution. The sericin extract was extracted by boiling and stirring in Na2CO3 solution at 100℃ for 1 hour, and then filtered while hot. The sericin extract was centrifuged at 10000 rpm for 15 minutes at low temperature to remove flocculent impurities. Then, it was mixed with 0.5M Tris-HCl buffer at a volume ratio of 3:1 and dialyzed in deionized water for 48 hours to obtain a relatively pure sericin protein stock solution. Next, the sericin protein stock solution was freeze-dried in vacuum at -80℃ for 3 days and ground to obtain a pure light yellow sericin protein powder. 0.3 g of sericin protein powder was added to 10 mL of the above PVA / PVP binary composite precursor solution and stirred in a water bath at 35℃ for 30 minutes. Then, it was naturally cooled to room temperature and transferred to a vacuum degassing chamber for degassing at a vacuum degree of 0.07 MPa for 40 minutes to obtain a PVA / PVP / serice protein ternary composite precursor solution.
[0070] S3. Inject the above PVA / PVP / sericin ternary composite precursor solution into the mold, control the liquid level to ensure uniform spreading of the solution without overflow, and begin the gradient freeze-thaw preparation: First, cool from room temperature to 3°C and maintain the temperature for 1 hour to complete the first stage of cooling induction and preliminary pre-nucleation; Second, cool from 3°C to -25°C and maintain the temperature for 2 hours to promote crystal nucleation and growth; Third, transfer to a cold trap and cool to -55°C and maintain the temperature for 1 hour to strengthen molecular chain cross-linking and pore structure formation; After the gradient freezing is completed, remove the mold and place it at room temperature for 5 hours to thaw, completing the gradient freeze-thaw preparation. Take out the hydrogel sample, rinse the surface with deionized water 4 times to remove surface impurities, and obtain the PVA / PVP / sericin ternary composite hydrogel.
[0071] S4. Dissolve 0.05g of potassium guaiacol sulfonate powder in 10mL of deionized water to obtain a potassium guaiacol sulfonate solution; then, immerse the above PVA / PVP / sericin ternary composite hydrogel in the potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate.
[0072] Example 5: This example provides a composite hydrogel dressing based on gradient freeze-thaw cycles, the preparation method of which includes the following steps:
[0073] S1: Dissolve 12.5g of polyvinyl alcohol (PVA) and 12.5g of polyvinylpyrrolidone (PVP) in 37.5g of deionized water, heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 6mL of polyvinyl alcohol solution and 4mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution;
[0074] S2. Cut several silkworm cocoons into pieces, rinse with deionized water to remove surface dust, take 25g of the cleaned silkworm cocoon pieces, and add 200mL of 0.15M solution. The sericin extract was extracted by boiling and stirring in Na2CO3 solution at 100℃ for 1 hour, and then filtered while hot. The sericin extract was centrifuged at 10000 rpm for 15 minutes at low temperature to remove flocculent impurities. Then, it was mixed with 1.5M Tris-HCl buffer at a volume ratio of 5:1 and dialyzed in deionized water for 48 hours to obtain a relatively pure sericin protein stock solution. Next, the sericin protein stock solution was freeze-dried in vacuum at -80℃ for 3 days and ground to obtain a pure light yellow sericin protein powder. 0.7 g of sericin protein powder was added to 10 mL of the above PVA / PVP binary composite precursor solution and stirred in a water bath at 45℃ for 30 minutes. Then, it was naturally cooled to room temperature and transferred to a vacuum degassing chamber for degassing at a vacuum degree of 0.09 MPa for 40 minutes to obtain a PVA / PVP / serice protein ternary composite precursor solution.
[0075] S3. Inject the above PVA / PVP / sericin ternary composite precursor solution into the mold, control the liquid level to ensure uniform spreading of the solution without overflow, and begin the gradient freeze-thaw preparation: First, cool from room temperature to 5°C and maintain the temperature for 2 hours to complete the first stage of cooling induction and preliminary pre-nucleation; Second, cool from 5°C to -15°C and maintain the temperature for 3 hours to promote crystal nucleation and growth; Third, transfer to a cold trap and cool to -45°C and maintain the temperature for 3 hours to strengthen molecular chain cross-linking and pore structure formation; After the gradient freezing is completed, remove the mold and place it at room temperature for 5 hours to thaw, completing the gradient freeze-thaw preparation. Take out the hydrogel sample, rinse the surface with deionized water 3 times to remove surface impurities, and obtain the PVA / PVP / sericin ternary composite hydrogel.
[0076] S4. Dissolve 0.15g of potassium guaiacol sulfonate powder in 10mL of deionized water to obtain a potassium guaiacol sulfonate solution; then, immerse the above PVA / PVP / sericin ternary composite hydrogel in the potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate.
[0077] Comparative Example 1: This comparative example provides a composite hydrogel dressing A1P1 based on gradient freeze-thaw cycles. Its preparation method differs from Example 1 in that it does not contain sericin and potassium guaiacol sulfonate. Specifically, it includes the following steps:
[0078] S1. Dissolve 10g of polyvinyl alcohol (PVA) and 10g of polyvinylpyrrolidone (PVP) in 40g of deionized water, and heat in a water bath to 90℃ for 1.5h until the polyvinyl alcohol and polyvinylpyrrolidone are completely dissolved to obtain polyvinyl alcohol solution and polyvinylpyrrolidone solution; then take 5mL of polyvinyl alcohol solution and 5mL of polyvinylpyrrolidone solution and mix them, and stir magnetically at 25℃ for 30min to obtain PVA / PVP binary composite precursor solution;
[0079] S2. The above PVA / PVP binary composite precursor solution is injected into the mold. The liquid level is controlled to ensure uniform spreading of the solution without overflow. Gradient freeze-thaw preparation begins: First, the temperature is lowered from room temperature to 4°C and held at a constant temperature for 1.5 hours to complete the first stage of cooling induction and preliminary pre-nucleation. Second, the temperature is lowered from 4°C to -20°C and held at a constant temperature for 3 hours to promote crystal nucleation and growth. Third, the temperature is transferred to a cold trap and lowered to -50°C and held at a constant temperature for 2 hours to strengthen molecular chain crosslinking and pore structure formation. After the gradient freezing is completed, the mold is removed and placed at room temperature for 5 hours to complete the gradient freeze-thaw preparation. The hydrogel sample is taken out and the surface is rinsed three times with deionized water to remove surface impurities, resulting in a PVA / PVP binary composite hydrogel, denoted as A1P1.
[0080] Performance Analysis and Testing: I. Total reflectance Fourier transform infrared spectroscopy (TFT) was performed on the composite hydrogel dressings A1P1S, A7P3S, and A3P7S prepared in Examples 1-3. The results are as follows: Figure 2 As shown: at 3350cm -1 A relatively broad absorption band was observed nearby, indicating the presence of stretching vibrations of OH and NH in the composite gel. At 2918 cm⁻¹... -1 The absorption peak is attributed to the stretching vibration of the methylene group. Meanwhile, at 1650 cm⁻¹... -1 The strong absorption peak is attributed to the C=O stretching vibration of the amide I band in PVP and the third component, sericin. Furthermore, the spectrum is located at 1480 cm⁻¹. -1 The peak also appears at 1290 cm⁻¹, which is due to the combined effect of the in-plane bending vibration of NH and the stretching vibration of CN in the amide II band of sericin. The amide III band is located at 1290 cm⁻¹. -1 The peaks are attributed to the asymmetric stretching vibrations of CN. The above spectral analyses all demonstrate that the introduction of the third component, sericin, successfully synthesized a ternary composite hydrogel.
[0081] II. Field emission electron microscopy analysis was performed on the composite hydrogel dressing A1P1S prepared in Example 1, and the results are as follows: Figure 3 As shown, the composite hydrogel dressing exhibits a gradient porous microstructure with pore sizes ranging from 2 to 20 µm. This indicates that the composite hydrogel dressing has successfully formed a three-dimensional spatial network through physical cross-linking, laying the foundation for the wound dressing to absorb tissue exudate and release drugs.
[0082] III. Tensile strength stress-strain tests were performed on the composite hydrogel dressings A1P1S, A7P3S, and A3P7S prepared in Examples 1-3. The results are as follows: Figure 4 As shown, the elongation at break of the A1P1S group reached nearly 220%. This is because the introduction of the PVP component reduced the self-crosslinking density of the pure PVA hydrogel, causing its internal structure to gradually loosen from tight to loose, increasing the space for movement and enhancing its ability to deform. The introduction of sericin further enhanced the elastic modulus and elongation at break of the hydrogel, improving its mechanical properties and making it better suited for wound repair in different scenarios. This prevents the dressing from tearing and breaking during use, maintaining its integrity and fit.
[0083] IV. Rheological properties of the composite hydrogel dressings A1P1S, A7P3S, and A3P7S prepared in Examples 1-3 were tested. Frequency scanning was performed at a strain of 1% to obtain the changes in storage modulus (G') and loss modulus (G'') within the frequency range of 0.1-100 rad / s. Figure 5 As shown in the figure. The results show that the storage modulus of the composite hydrogel dressings A1P1S, A7P3S, and A3P7S are consistently higher than their loss modulus, indicating the successful synthesis of the hydrogel and its good elasticity. Simultaneously, the results indicate that the storage modulus of composite hydrogel dressing A1P1S is significantly higher than that of other composite hydrogel dressings, suggesting higher rigidity and strength, and improved mechanical properties.
[0084] V. The adhesion properties of the composite hydrogel dressing A1P1S prepared in Example 1 were tested, and the results are as follows: Figure 6 As shown, the composite hydrogel dressing A1P1S exhibits excellent adhesion to different substrates. Even when inverted, the hydrogel does not fall off, which maintains the stability and fit of the wound dressing on the wound surface, ensuring a close fit and preventing displacement or detachment.
[0085] VI. In vitro antibacterial experiments were conducted on the composite hydrogel dressing A1P1S prepared in Example 1 and the composite hydrogel dressing A1P1 prepared in Comparative Example 1. The antibacterial effects of composite hydrogel dressings A1P1S and A1P1 against Pseudomonas aeruginosa and Staphylococcus aureus within 24 hours were evaluated using the plate coating method. The results are as follows: Figure 7As shown, compared with the control group A1P1, A1P1S exhibited a significant antibacterial effect, enabling its dressing to reduce the risk of infection, prevent the aggravation of inflammation, and create an optimized healing microenvironment.
[0086] VII. The composite hydrogel dressing A1P1S prepared in Example 1 was tested for 24-hour cell compatibility. The results are as follows: Figure 8 As shown, the composite hydrogel dressing A1P1S has no obvious toxicity to cells and has good biocompatibility.
[0087] 8. In vitro blood compatibility tests were conducted on the composite hydrogel dressings A1P1S, A7P3S, and A3P7S prepared in Examples 1-3, and the composite hydrogel dressing A1P1 prepared in Comparative Example 1. The negative control group consisted of PBS and 2% red blood cell suspension, the positive control group consisted of deionized water and 2% red blood cell suspension, and the experimental groups consisted of A1P1, A1P1S, A7P3S, and A3P7S co-incubated with red blood cell suspension. The results are as follows: Figure 9 As shown, all composite hydrogel dressings showed no obvious hemolysis and had good blood compatibility.
[0088] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.
Claims
1. A method for preparing a composite hydrogel dressing based on gradient freeze-thaw cycles, characterized in that, Includes the following steps: A binary composite precursor solution was obtained by mixing a polyvinyl alcohol solution and a polyvinylpyrrolidone solution. Sericin powder was mixed with a binary composite precursor solution to obtain a ternary composite precursor solution. The ternary composite precursor solution was injected into a mold and prepared by gradient freeze-thaw method to obtain ternary composite hydrogel. A ternary composite hydrogel was impregnated in a potassium guaiacol sulfonate solution to form a composite hydrogel dressing loaded with potassium guaiacol sulfonate.
2. The method for preparing the composite hydrogel dressing based on gradient freeze-thaw as described in claim 1, characterized in that, The polyvinyl alcohol solution has a mass concentration of 15-25 wt%; the polyvinylpyrrolidone solution has a mass concentration of 15-25 wt%; and the volume ratio of the polyvinyl alcohol solution to the polyvinylpyrrolidone solution is 7-3:3-7.
3. The method for preparing the composite hydrogel dressing based on gradient freeze-thaw as described in claim 1, characterized in that, The method for preparing the sericin powder is as follows: sericin is extracted from silkworm cocoons using a hot alkali degumming method, then freeze-dried and ground to obtain sericin powder.
4. The method for preparing the composite hydrogel dressing based on gradient freeze-thaw as described in claim 3, characterized in that, The preparation method of the sericin protein powder specifically includes the following steps: Several silkworm cocoons were cut into pieces, added to Na2CO3 solution and boiled for extraction, and then filtered while hot to obtain sericin extract. The sericin extract was centrifuged to remove flocculent impurities, then mixed evenly with Tris-HCl buffer and dialyzed in deionized water to obtain a sericin protein source solution. The original solution of sericin was freeze-dried under vacuum and then ground to obtain sericin powder.
5. The method for preparing a gradient freeze-thaw based composite hydrogel dressing according to claim 1, 3, or 4, characterized in that, The step of mixing sericin powder with the binary composite precursor solution specifically includes: adding sericin powder to the binary composite precursor solution, stirring at 35-45℃, then naturally cooling to room temperature, and degassing under a vacuum of 0.07-0.09MPa.
6. The method for preparing the composite hydrogel dressing based on gradient freeze-thaw as described in claim 5, characterized in that, The mass-to-volume ratio of the sericin powder to the binary composite precursor solution is (3-7) g: 100 mL.
7. The method for preparing a composite hydrogel dressing based on gradient freeze-thaw as described in claim 1, characterized in that, The gradient freeze-thaw method specifically includes the following steps: Gradient freezing: The first stage is to cool from room temperature to 3-5℃ and maintain the temperature for 1-2 hours; the second stage is to cool to -25~-15℃ and maintain the temperature for 2-4 hours; the third stage is to cool to -55~-45℃ and maintain the temperature for 1-3 hours. Thawing process: After the gradient freezing is completed, place it at room temperature for static thawing for 4-6 hours to complete the gradient freeze-thaw preparation.
8. The method for preparing the composite hydrogel dressing based on gradient freeze-thaw as described in claim 1, characterized in that, The method for preparing the potassium guaiacol sulfonate solution is as follows: potassium guaiacol sulfonate powder is dissolved in deionized water to obtain potassium guaiacol sulfonate solution; the mass-volume ratio of potassium guaiacol sulfonate powder to deionized water is (0.5-1.5) g: 100 mL.
9. A composite hydrogel dressing prepared by any one of the preparation methods described in claims 1-8.
10. The use of the composite hydrogel dressing as described in claim 9 in the preparation of wound healing drugs.