Composite hydrogel dressing for chronic wound repair as well as preparation method and application of composite hydrogel dressing

Abstract

The invention belongs to the field of tissue engineering and wound repair, and relates to a composite hydrogel dressing for chronic wound repair and a preparation method and application thereof.The preparation method comprises the steps that S1, cinnamyl aldehyde is dispersed in a gelatin aqueous solution, and dialysis is conducted till the solution is clear after the reaction is sufficient; freeze-drying to obtain cinnamyl aldehyde grafted modified gelatin; s2, mixing mattress removing and tissue regeneration promoting powder, the cinnamyl aldehyde grafted modified gelatin obtained in the step S1, methacrylated gelatin and a photoinitiator in a PBS solution to obtain a mixed solution; s3, adding a Ga (NO3) 3.6 H2O solution into the mixed solution obtained in the step S2 to obtain a hydrogel precursor solution; s4, the hydrogel precursor solution obtained in S3 is used for 3D printing and photocuring, and the composite hydrogel dressing is obtained. According to the invention, the medicine powder is embedded and slowly released through a three-dimensional network formed by GelMA, CA-Gel and gallium ions, so that efficient antibiosis, healing promotion and structural support on chronic wounds are realized, and the treatment effect and the use safety are improved.

Description

Technical Field

[0001] This invention relates to the fields of tissue engineering and wound repair, specifically to a composite hydrogel dressing for chronic wound repair, its preparation method, and its application. Background Technology

[0002] Chronic wounds, such as pressure ulcers and skin lesions caused by diabetes, are often characterized by high incidence, long healing periods, and complex pathological features including bacterial infection, large exudates, and low tissue regeneration capacity. Research has found that current clinical treatments often utilize traditional Chinese medicine powder dressings such as "Pressure-Restoring and Tissue-Regenerating Powder." However, this powder is primarily composed of various plant-based medicinal materials that have been directly pulverized and mixed. Applied to the wound in dry powder form, it cannot effectively retain fluids in a moist, exudative environment, easily escaping with bodily fluids. This results in low utilization of the active ingredients, short duration of action, and frequent reapplication. Furthermore, like traditional dry dressings, the powder cannot provide the microenvironment necessary for moist healing. Excessive use can lead to over-absorption, scab formation, and bacterial growth, hindering wound healing. Additionally, the powder lacks a stable physical support structure and cannot form a three-dimensional scaffold conducive to tissue repair, limiting its ability to promote cell adhesion, proliferation, and collagen deposition. These shortcomings limit its clinical efficacy.

[0003] Patent CN202311592931.0 discloses a hydrogel / gauze composite dressing capable of scavenging reactive oxygen species and its preparation method. The method includes: mixing and stirring a methacrylamide-modified natural polymer solution, an aldehyde-modified natural polymer solution, and a photoinitiator to obtain a precursor solution; soaking gauze in the precursor solution; and then molding the hydrogel / gauze composite dressing in situ under ultraviolet light irradiation. Finally, an antioxidant hydrogel / gauze composite dressing is obtained by crosslinking gallic acid. In this invention, the carboxyl group of gallic acid undergoes an amide reaction with the amino group of the natural polymer, and the phenolic hydroxyl group of gallic acid forms hydrogen bonds with the polymer to improve mechanical properties. The phenolic hydroxyl group of gallic acid synergistically enhances adhesion properties with the aldehyde-modified natural polymer. Simultaneously, the slow release of gallic acid endows the hydrogel / gauze composite dressing with a long-lasting ability to scavenge reactive oxygen species, regulating the tissue microenvironment at the skin wound site and promoting wound healing. However, when the above-mentioned patents are applied to large-area or irregularly shaped wounds, traditional gauze-shaped sheet dressings are difficult to fit tightly to the wound, and the gaps can easily become hidden sites of infection. Summary of the Invention

[0004] In recent years, hydrogels have been considered ideal wound dressing materials due to their high water content, soft and conformable texture, controllable drug release, and ability to create a moist healing environment. Among them, photocrosslinked methacrylated gelatin (GelMA) can rapidly gel through the action of photoinitiators and possesses good cell compatibility; however, its mechanical properties are limited, and it lacks anti-inflammatory, antioxidant, and other bioactive functions, making it difficult to effectively address the complex repair environment of chronic wounds. Natural small-molecule cinnamaldehyde, on the other hand, possesses anti-inflammatory, antioxidant, and certain antibacterial activities. Grafting gelatin through a Schiff base reaction can endow hydrogels with additional biological functions. Furthermore, research has shown that gallium ions (Ga... 3+ Ga can mimic the binding of iron ions to bacterial enzyme systems, thereby interfering with microbial metabolism and exhibiting antibacterial effects. Meanwhile, Ga... 3+ As a multivalent cation, Ga can coordinate with the carboxyl and hydroxyl groups in gelatin or gelMA to form additional ionic cross-linking networks, thereby improving the mechanical strength and structural stability of the hydrogel. Therefore, Ga... 3+ Introducing it into hydrogel systems is expected to further enhance their antibacterial and mechanical properties.

[0005] 3D bioprinting places high demands on bio-inks. Addressing issues such as excessive reactive oxygen species and persistent inflammation in chronic wounds, traditional Chinese medicine powder is used as a solid filler to improve the system's viscosity and yield stress. This allows the ink to be easily extruded under high shear and rapidly recover its structure under low shear conditions, achieving excellent shear-thinning behavior and shape retention. Simultaneously, the weak interactions between the powder and gel components construct a stable particle-polymer composite network, effectively preventing printing collapse, sagging, and diffusion.

[0006] Addressing the shortcomings of powder dressings like those for treating dandruff and promoting tissue regeneration, as well as existing hydrogel dressings, such as the difficulty in fixing the powder, uneven application, caking due to liquid absorption, and difficulty in maintaining a moist healing environment, this invention proposes the development of a novel wound dressing material that simultaneously achieves stable utilization of traditional Chinese medicine components, construction of a moist microenvironment, sustained antibacterial action, and tissue regeneration support. The resulting hydrogel precursor solution is then used for 3D bioprinting to create personalized wound dressings suitable for various irregular wound shapes. In this invention, a three-dimensional network formed by GelMA, CA-Gel, and gallium ions encapsulates and sustains the release of the medicinal powder, achieving highly effective antibacterial action, promoting healing, and providing structural support for chronic wounds, thus improving treatment efficacy and safety.

[0007] The objective of this invention can be achieved through the following technical solutions: One objective of this invention is to provide a method for preparing a composite hydrogel dressing for chronic wound repair, comprising the following preparation method: S1. Cinnamaldehyde was dispersed in an aqueous gelatin solution, and after the reaction was complete, the solution was dialyzed until it became clear. After freeze-drying, cinnamaldehyde-grafted modified gelatin was obtained, denoted as CA-Gel. S2. Mix the bedwetting and muscle-regenerating powder, the cinnamaldehyde-grafted modified gelatin obtained in S1, the methacrylated gelatin, and the photoinitiator in PBS solution to obtain a mixed solution. S3. Add Ga(NO3)3·6H2O solution to the mixed solution obtained in S2 to obtain the hydrogel precursor solution; S4. Using the hydrogel precursor solution obtained in S3, perform 3D printing and photocuring to obtain a composite hydrogel dressing for chronic wound repair.

[0008] Furthermore, the gelatin aqueous solution is acidic, preferably with a pH of 5.8.

[0009] Furthermore, the ratio of the gelatin to the cinnamaldehyde is (3-7) g : (1-2) mL.

[0010] Furthermore, the reaction temperature is 30-40℃, and the reaction time is 12-36h.

[0011] Furthermore, the dialysate used in the dialysis is physiological saline, and the dialysis time is 24-72 hours.

[0012] Furthermore, the mass ratio of the bedwetting and skin-regenerating powder, cinnamaldehyde-grafted modified gelatin, methacrylated gelatin, and photoinitiator is (20-70): (200-300): (200-300): (3-7), preferably 25: 250: 250: 5.

[0013] Furthermore, the mixing temperature in the mixed solution is 40-50℃.

[0014] Furthermore, the hydrogel precursor solution is neutral.

[0015] The second objective of this invention is to provide a composite hydrogel dressing for chronic wound repair, which is prepared using the method described above.

[0016] A third objective of this invention is the application of the composite hydrogel dressing for chronic wound repair as described above. Optionally, the chronic wound may be an irregularly shaped wound.

[0017] Compared with existing technologies, this invention provides a composite hydrogel dressing for chronic wound repair. The powder is embedded in a GelMA / CA-Gel network structure, achieving fixation and uniform dispersion of the wound healing powder, preventing loss or accumulation due to wound exudate. It also allows for drug release during gel degradation, resulting in a more lasting and uniform efficacy. Furthermore, it avoids the problems of irritation, hardening, and secondary damage caused by powder accumulation in traditional dry powder treatments. The addition of microparticles significantly increases the viscosity of the precursor solution, enhancing the material's printability and structural formability, resulting in straight, non-collapsed extruded lines, which is beneficial for printing precise, complex, and personalized wound structures. The resulting hydrogel dressing shows a DPPH clearance rate increased from 23.18% with pure GelMA to 76.73% with 1% powder within half an hour. Gallium ions provide broad-spectrum antibacterial function, and the wound healing powder and CA-Gel work together to promote granulation tissue formation, significantly improving overall antioxidant, antibacterial, and healing-promoting properties. Among them, the powder particles, as physical reinforcing fillers, improve the tensile strength of the hydrogel, enhance its mechanical properties, and significantly improve its structural support capacity, making the dressing more stable and durable in the wound environment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the preparation process of the present invention; Figure 2 The proton NMR spectrum of the hydrogel wound dressing prepared in an embodiment of the present invention; Figure 3 The ultraviolet absorption spectrum of the hydrogel wound dressing prepared in this embodiment of the invention; Figure 4 SEM images of traditional Chinese medicine powder added in embodiments of the present invention; Figure 5 The shear rate and viscosity curves of different hydrogel precursor solutions at 25°C are shown in the embodiments of the present invention. Figure 6 The tensile mechanical properties of the hydrogel prepared in the embodiments of the present invention are shown in the figure. Figure 7 The figure shows the DPPH clearance test results of the hydrogel wound dressing prepared in the embodiment of the present invention; Figure 8 This is a physical image of the 3D-printed hydrogel wound dressing prepared according to an embodiment of the present invention.

[0019] The numbers in the diagram indicate: 1 - 3D printing syringe; 2 - UV lamp; 3 - 3D printing hydrogel. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0021] Example 1 This embodiment provides a GelMA / CA-Gel / Ga 3+ (referred to as GMGCA / Ga) 3+ The preparation method of adding 0.5% drug hydrogel includes the following steps: S1. Dissolve 5 g of gelatin in 100 mL of pure water, stir and heat to 40 °C until the gelatin is completely dissolved and a homogeneous solution is formed. Then adjust the pH to 5.8 with phosphate buffer, and then slowly add 1.89 mL of cinnamaldehyde to the solution while stirring constantly to ensure that the cinnamaldehyde is evenly distributed in the solution. React at 35 °C for 24 h, keeping the pH in a slightly acidic range during the reaction. Place the resulting solution in a dialysis bag and dialyze with physiological saline for 48 h until the solution is clear. Then obtain cinnamaldehyde-grafted modified gelatin (CA-Gel) by freeze-drying. S2. Take 25 mg of bedwetting and muscle-regenerating powder (the bedwetting and muscle-regenerating powder used in this example is a commercially available product, purchased from Tonghe Zhencheng Health Flagship Store, whose main ingredients include chicken blood vine, angelica dahurica, blood scorpion, coptis chinensis, calamine, borneol, etc.) and evenly disperse it in PBS (4 mL). Dissolve the CA-Gel (250 mg) and GelMA (250 mg) obtained in S1 and the photoinitiator (LAP, 5 mg) in 4 mL of PBS respectively. Stir at 40-50℃ until all the added materials are dissolved to obtain a mixed solution. S3. Dissolve 40 mg of Ga(NO3)3·6H2O in 1 mL of PBS, add the mixture obtained in S2 dropwise, adjust the pH of the mixture to neutral, stir and mix evenly to obtain the hydrogel precursor solution. S4. Using an extrusion 3D bioprinter, the hydrogel precursor solution obtained in S3 is printed into a preset shape, and then cured by ultraviolet light to obtain GMGCA / Ga 3+ Add 0.5% hydrogel. Specifically, from Figure 1 As can be seen, the obtained hydrogel precursor solution was used to obtain a hydrogel scaffold using a 3D printing syringe 1. The scaffold was then placed under a UV lamp 2 for photocuring to form a 3D printed hydrogel 3.

[0022] from Figure 2 and Figure 3It can be seen that the modified gelatin exhibits a new allyl peak (approximately 6.2–7.7 ppm) in its 1H NMR spectrum, and also shows a π→π* transition between the aromatic ring and the conjugated C=C / C=N ring at a wavelength of 279 nm. These results indicate that the cinnamaldehyde structure has been successfully grafted onto gelatin, and this method can yield cinnamaldehyde-grafted modified gelatin.

[0023] according to Figure 4 As shown in the SEM images, the anti-bedsore skin-regenerating powder appears as irregular flake / granular solid particles (1–20 μm) with a large specific surface area and a rough surface. These solid microparticles can form a particle skeletal network in the hydrogel precursor solution, improving the structural stability of the system under low shear conditions. Therefore, in Figure 5 In the middle, at 25℃, through GMGCA / Ga 3+ The system incorporates micron-sized traditional Chinese medicine powder to form a "polymer-particle composite network." Even without changing the concentrations of GelMA and CA-Gel, their addition significantly improves the yield stress and viscoelasticity of the precursor solution, making the material easy to extrude under high shear and quickly recover viscosity under low shear, thereby achieving high-precision and high-stability forming of the printed structure.

[0024] from Figure 6 The mechanical tensile diagram shows that, through GMGCA / Ga 3+ By introducing micron-sized tissue-regenerating and wound-healing powder into the system, this invention significantly improves the tensile strength and toughness of the hydrogel dressing while maintaining printability. The powder, acting as a microfiller, interacts with the polymer network at the interface, enhancing mechanical load-bearing capacity and delaying crack propagation through interfacial dissipation mechanisms. This results in significantly enhanced tensile strength, tear resistance, and conformability of the final printed dressing during use.

[0025] from Figure 7 It can be seen that by combining cinnamaldehyde-grafted gelatin with GelMA and further introducing wound healing and tissue regeneration powder, significant antioxidant properties that cannot be obtained by traditional gelatin hydrogels are achieved. Its antioxidant capacity is not only several times higher than that of GelMA hydrogel, but the scavenging rate of the 1% drug group reached 76.73%, which is slightly higher than that of 0.5% (62.61%), showing its dose-dependent and synergistic effect. This indicates that this composite strategy can effectively scavenge free radicals in a short time and significantly improve the wound microenvironment.

[0026] Example 2 This embodiment provides a GelMA / CA-Gel / Ga 3+ (referred to as GMGCA / Ga) 3+ The preparation method of the 1% drug-coated hydrogel includes the following steps: S1. Dissolve 5 g of gelatin in 100 mL of pure water, stir and heat to 40 °C until the gelatin is completely dissolved and a homogeneous solution is formed. Then adjust the pH to 5.8 with phosphate buffer, and then slowly add 1.89 mL of cinnamaldehyde to the solution while stirring constantly to ensure that the cinnamaldehyde is evenly distributed in the solution. React at 35 °C for 24 h, keeping the pH in a slightly acidic range during the reaction. Place the resulting solution in a dialysis bag and dialyze with physiological saline for 48 h until the solution is clear. Then obtain cinnamaldehyde-grafted modified gelatin (CA-Gel) by freeze-drying. S2. Take 50 mg of bedwetting and muscle-regenerating powder (the bedwetting and muscle-regenerating powder used in this example is a commercially available product, purchased from Tonghe Zhencheng Health Flagship Store, whose main ingredients include chicken blood vine, angelica dahurica, blood scorpion, coptis chinensis, calamine, borneol, etc.) and evenly disperse it in PBS (4 mL). Dissolve the CA-Gel (250 mg) and GelMA (250 mg) obtained in S1 and the photoinitiator (LAP, 5 mg) in 4 mL of PBS respectively. Stir at 40-50℃ until all the added materials are dissolved to obtain a mixed solution. S3. Dissolve 40 mg of Ga(NO3)3·6H2O in 1 mL of PBS, add the mixture obtained in S2 dropwise, adjust the pH of the mixture to neutral, stir and mix evenly to obtain the hydrogel precursor solution. S4. Using an extrusion 3D bioprinter, the hydrogel precursor solution obtained in S3 is printed into a preset shape, and then cured by ultraviolet light to obtain GMGCA / Ga 3+ Add 1% medicated gel.

[0027] Comparative Example 1 This embodiment provides a GMGCA / Ga 3+ The preparation method of hydrogel includes the following steps: S1. Dissolve 5 g of gelatin in 100 mL of pure water, stir and heat to 40 °C until the gelatin is completely dissolved and a homogeneous solution is formed. Then adjust the pH to 5.8 with phosphate buffer, and then slowly add 1.89 mL of cinnamaldehyde to the solution while stirring constantly to ensure that the cinnamaldehyde is evenly distributed in the solution. React at 35 °C for 24 h, keeping the pH in a slightly acidic range during the reaction. Place the resulting solution in a dialysis bag and dialyze with physiological saline for 48 h until the solution is clear. Then obtain cinnamaldehyde-grafted modified gelatin (CA-Gel) by freeze-drying. S2. Dissolve the CA-Gel (250 mg), GelMA (250 mg), and photoinitiator (LAP, 5 mg) obtained in S1 in 4 mL of PBS, and stir at 40-50℃ until all the added materials are dissolved to obtain a mixed solution. S3. Dissolve 40 mg of Ga(NO3)3·6H2O in 1 mL of PBS, add the mixture obtained in S2 dropwise, adjust the pH of the mixture to neutral, stir and mix evenly to obtain the hydrogel precursor solution. S4. Using an extrusion 3D bioprinter, the hydrogel precursor solution obtained in S3 is printed into a preset shape, and then cured by ultraviolet light to obtain GMGCA / Ga 3+ Hydrogel dressing.

[0028] The difference between Examples 1 and 2 and Comparative Example 1 lies in whether or not bedwetting-regenerating powder was added and the dosage, which directly leads to significant differences in the microstructure and core properties of the hydrogel. Comparative Example 1 did not add any bedwetting-regenerating powder; Example 1, with the same basic components and dosage as Comparative Example 1, added an additional 25 mg of bedwetting-regenerating powder (corresponding to a 0.5% drug concentration) and evenly dispersed it in 4 mL of PBS; Example 2, with the same basic system, added 50 mg of bedwetting-regenerating powder (corresponding to a 1% drug concentration), and the remaining components and dosages were completely consistent with Comparative Example 1 and Example 1.

[0029] Comparative Example 1 consists only of GelMA and CA-Gel, forming a pure polymer network structure. This structure mainly relies on chemical cross-linking to maintain overall stability. Under low shear conditions, the structural support capacity is limited and it is prone to collapse. Examples 1 and 2 introduce microparticles of the anti-bedsore and muscle-regenerating powder. The system further constructs a composite network structure in which the polymer network and solid particles work together. The powder microparticles are uniformly dispersed in the three-dimensional polymer network, playing a role in physical support and structural reinforcement under low shear rates, which is beneficial to improving the structural stability and yield behavior of the precursor system. Compared to the pure polymer network hydrogel of Comparative Example 1, the hydrogels of Examples 1 and 2, while maintaining good shear-thinning properties and printability, also showed significantly improved yield stress and viscoelasticity, which is beneficial for achieving high-precision and high-stability molding of printed structures. The composite hydrogels obtained after curing exhibited higher fracture strength and toughness in tensile tests. This is because the powder particles, acting as microscale fillers, form interfacial interactions with the polymer chains, sharing the external load, inhibiting crack initiation, and delaying crack propagation during stress, thus significantly improving the overall mechanical strength. The anti-wound healing powder contains various natural active ingredients that synergistically work with CA-Gel, greatly enhancing the antioxidant properties of the composite hydrogel, exhibiting a certain dose-dependent effect. The clearance rate in Example 1 was 62.61%, and in Example 2, it increased to 76.73%, a 30%-65% improvement compared to 46.79% in Comparative Example 1. Therefore, the introduction of anti-wound healing powder not only improves the rheological and mechanical properties of the material but also significantly expands the functional advantages of hydrogels in chronic wound repair.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite hydrogel dressing for chronic wound repair, characterized by, The preparation method comprises the following steps: S1, dispersing cinnamyl aldehyde in gelatin aqueous solution, dialyzing until the solution is clear after sufficient reaction, and obtaining cinnamyl aldehyde grafted modified gelatin by freeze-drying; S2, mixing Qudux Shengji powder, cinnamyl aldehyde grafted modified gelatin obtained in S1, methacrylated gelatin and photoinitiator in PBS solution to obtain a mixed solution; S3, adding Ga(NO3)3·6H2O solution to the mixed solution obtained in S2 to obtain a hydrogel precursor solution; S4, using the hydrogel precursor solution obtained in S3 to perform 3D printing and photocuring to obtain a composite hydrogel dressing for chronic wound repair.

2. The method of claim 1, wherein the method is for preparing a composite hydrogel dressing for chronic wound repair. The gelatin aqueous solution is acidic.

3. The method of claim 1, wherein the method is characterized by: The ratio of the gelatin to the cinnamyl aldehyde is (3-7) g :(1-2) mL.

4. The method of claim 1, wherein the method is characterized by: The reaction temperature in S1 is 30-40℃, and the reaction time is 12-36 h.

5. The method of claim 1, wherein the method is characterized by: The dialysis liquid in the dialysis in S1 is normal saline, and the dialysis time is 24-72 h.

6. The method of claim 1, wherein the method is for preparing a composite hydrogel dressing for chronic wound repair. The mass ratio of the Qudux Shengji powder, cinnamyl aldehyde grafted modified gelatin, methacrylated gelatin and photoinitiator is (20-70):(200-300):(200-300):(3-7).

7. The method of claim 1, wherein the method is for preparing a composite hydrogel dressing for chronic wound repair. The mixing temperature in the mixed solution is 40-50℃.

8. The method of claim 1, wherein the method is for preparing a composite hydrogel dressing for chronic wound repair. The hydrogel precursor solution is neutral.

9. A composite hydrogel dressing for chronic wound repair, characterized by, It is prepared by the preparation method in any one of claims 1-8.

10. Use of a composite hydrogel dressing for chronic wound repair according to claim 9, wherein, It is applied in chronic wound repair.

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