A biodegradable medical dressing and its preparation method

Abstract

This invention discloses a biodegradable medical dressing and its preparation method, relating to the field of medical dressing technology. The preparation method includes the following steps: adding sodium carboxymethyl cellulose and hydroxypropyl cellulose to deionized water, stirring evenly, adding 10wt% hydrochloric acid solution and epichlorohydrin, adjusting the pH of the solution to 0.2-0.5 to obtain a porous foam fabric; adding a polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, adding diphenylmethane diisocyanate and dibutyltin dilaurate, heating and reacting under a nitrogen atmosphere, adding imidazolidinyl urea, keeping the reaction at a constant temperature, adding dihydroporphyrin E6 to obtain a hydrogel dressing; cutting the porous foam fabric, immersing part of the fabric in the hydrogel dressing, drying it, and then treating it with tannic acid-silicate to obtain the biodegradable medical dressing.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, specifically a biodegradable medical dressing and its preparation method. Background Technology

[0002] In treating burns caused by overheating or corrosive chemicals, the choice of wound dressing is crucial to the healing process. While traditional dressings can provide some protection in certain situations, their effectiveness may be limited when dealing with burn wounds. An ideal wound dressing should possess several key characteristics: First, it needs to be able to flexibly conform to the irregular shape of the burn wound; second, it should be able to absorb wound exudate while maintaining a suitable moist environment to promote the healing process; third, the dressing material should have good biocompatibility to effectively prevent wound infection; and finally, the dressing change process should minimize secondary damage to the wound and avoid the pain and discomfort caused by high adhesion.

[0003] Hydrogel dressings are widely used in modern medicine due to their superior physical and biological properties, especially in burn treatment. Hydrogels not only possess excellent wettability, maintaining ideal moisture levels on the wound surface during healing, but also exhibit superior softness and adhesion, adapting well to irregular wound shapes and reducing damage during dressing changes. Furthermore, the high water content and biocompatibility of hydrogel dressings effectively promote wound healing, reduce inflammation, and prevent secondary infections.

[0004] With the increasing demand for burn treatment, the problem of adhesion during dressing changes urgently needs to be solved. Therefore, inventing a biodegradable medical dressing is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a biodegradable medical dressing and its preparation method to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a biodegradable medical dressing includes the following steps: S1: Sodium carboxymethyl cellulose and hydroxypropyl cellulose are added to deionized water and stirred evenly. 10wt% hydrochloric acid solution and epichlorohydrin are added to adjust the pH of the solution to 0.2-0.5. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1-1.5 hours, then frozen to -20 to -18℃ for 20-22 hours. After thawing, the mixture is washed with deionized water and dried in an environment of 40-45℃ for 24 hours to obtain a porous foam fabric.

[0008] S2: Add the polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75-80℃, stir until homogeneous, rinse with nitrogen, add diphenylmethane diisocyanate and dibutyltin dilaurate N,N-dimethylformamide solution, heat to 75-80℃ under nitrogen atmosphere and react for 5-6 hours, add imidazolidinyl urea, keep warm and react for 4-4.5 hours, add dry N,N-dimethylformamide, stir until homogeneous, add dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0009] S3: After cutting the porous foam fabric, partially immerse it in the hydrogel dressing, dry it, and then treat it with tannic acid-silicate to obtain a biodegradable medical dressing.

[0010] Furthermore, in the preparation process of the porous foam fabric, the mass ratio of sodium carboxymethyl cellulose to hydroxypropyl cellulose is 0.6:(0.3-0.5).

[0011] Furthermore, in the preparation process of the hydrogel dressing, the molar ratio of polyethylene glycol precursor containing β-aminoacrylate bonds: diphenylmethane diisocyanate: imidazolidinyl urea: dihydroporphyrin E6 is (0.3-0.4):(2-3):(1.7-1.9):0.003.

[0012] Furthermore, the preparation method of the polyethylene glycol precursor containing β-aminoacrylate bonds includes the following steps: Step (1): polyethylene glycol, propynic acid, and p-toluenesulfonic acid hydrate are added to toluene, heated to reflux for 24 hours under a nitrogen atmosphere, concentrated under reduced pressure, and the product is added to diethyl ether to precipitate, thereby obtaining functionalized polyethylene glycol.

[0013] Step (2): Add functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30-32℃ and stir until homogeneous, add diethanolamine, keep warm for 1-1.5h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain polyethylene glycol precursor containing β-amino acrylate bonds.

[0014] Furthermore, in the preparation process of the functionalized polyethylene glycol, the mass ratio of polyethylene glycol:propynic acid:p-toluenesulfonic acid hydrate is 10:(3.57-3.76):(1.52-1.55).

[0015] Furthermore, in the preparation process of the polyethylene glycol precursor containing β-aminoacrylate bonds, the molar ratio of functionalized polyethylene glycol to diethanolamine is 1:3.

[0016] Furthermore, the specific process of the tannic acid-silicate treatment includes: adding tannic acid to deionized water, stirring evenly, immersing the portion of the dried porous foam fabric containing hydrogel dressing in it, adding a hyaluronic acid solution containing potassium silicate, stirring evenly, soaking for 3-4 days, and then drying.

[0017] Furthermore, in the tannic acid-silicate treatment process, the concentration of the tannic acid solution in deionized water is 10-30 wt%; in the hyaluronic acid solution containing potassium silicate, the solvent is a hyaluronic acid solution with a concentration of 4-5 mg / mL, and the amount of potassium silicate added is 0.04-0.05 g / mL.

[0018] Furthermore, the drying process includes any one of natural air drying, constant temperature drying, or vacuum drying.

[0019] Furthermore, the porous foam fabric is immersed in the hydrogel dressing for 0.5-2 hours, and the drying process takes 2-10 hours.

[0020] Furthermore, the biodegradable medical dressing structure includes: an upper part being a porous foam fabric with a porous foam structure, and a lower part being a hydrogel dressing containing tannic acid-silicate treated material.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention uses carboxymethyl cellulose through double crosslinking and pore-forming agent leaching to construct a porous foam fabric with a hierarchical pore structure. This not only disperses stress at multiple scales and gives the porous foam fabric super elasticity, but also allows it to deeply absorb biological fluids (blood and body fluids) through its hierarchical porous surface and strong wetting power from abundant hydrophilic groups (such as hydroxyl and carboxyl groups). It exhibits better absorbency than commercial elastic polyurethane foam, which is beneficial to improving the healing rate of patient wounds and can be completely degraded in the body and in soil.

[0023] 2. To alleviate the pain caused by cell adhesion dressings during burn wound dressing changes, and in addition to the porous foam fabric prepared above for absorbing continuously deep biological fluids in the wound, this invention prepares a polyethylene glycol containing a β-aminoacrylate structure. Using this as a raw material, an imidazolidinyl urea-reinforced polyurethane hydrogel dressing is further prepared. Finally, through various non-covalent interactions, tannic acid and silicate are loaded into the hydrogel dressing network. On the one hand, tannic acid and silicate can eliminate the overexpression of reactive oxygen species, combat infection, and create a microenvironment favorable to cells to accelerate in vitro wound healing. On the other hand, the hydrogel dressing continuously absorbs bodily fluids at the wound site. When the absorption of bodily fluids reaches saturation, the upper porous foam fabric will absorb the bodily fluids. When this occurs, it indicates that the dressing needs to be changed. Visible light can be used to irradiate the medical dressing, causing it to lose its mechanical strength and cell adhesion properties, allowing it to fall off naturally. This greatly reduces the pain of injured patients and significantly expands the application scenarios of medical dressings. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0025] In the following examples, the specifications of sodium carboxymethyl cellulose were: degree of substitution = 0.72, molecular weight = 85000; the specifications of hydroxypropyl cellulose were: degree of substitution = 0.52, molecular weight = 110000; the specifications of polyethylene glycol were: Mn = 4000 g / mol; the specifications of tannic acid were: Mw = 800 kDa; the specifications of hyaluronic acid were: Mw = 400 kDa; the commercially available PU foam fabric model was: 3M, 90619; and all other raw materials were commercially available.

[0026] Example 1: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0027] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0028] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0029] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0030] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 10wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 4 mg / mL, and the amount of potassium silicate added is 0.04 g / mL.

[0031] Example 2: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0032] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0033] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0034] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0035] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 30wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 5 mg / mL, and the amount of potassium silicate added is 0.05 g / mL.

[0036] Comparative Example 1: A method for preparing a biodegradable medical dressing, comprising the following steps: preparing functionalized polyethylene glycol using polyethylene glycol with a molecular weight of 1000;

[0037] The remaining steps are the same as in Example 1.

[0038] Comparative Example 2: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0039] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0040] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0041] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, and obtain hydrogel dressing;

[0042] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 10wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 4 mg / mL, and the amount of potassium silicate added is 0.04 g / mL.

[0043] Comparative Example 3: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0044] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under a nitrogen atmosphere, concentrate under reduced pressure, and precipitate the product in diethyl ether to obtain functionalized polyethylene glycol; wherein the molecular weight of polyethylene glycol is 1000.

[0045] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0046] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, and obtain hydrogel dressing;

[0047] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 10wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 4 mg / mL, and the amount of potassium silicate added is 0.04 g / mL.

[0048] Comparative Example 4: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0049] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0050] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0051] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0052] S5: After cutting the porous foam fabric, partially immerse it in the hydrogel dressing, and after drying, obtain a biodegradable medical dressing.

[0053] Comparative Example 5: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0054] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0055] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0056] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0057] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 5wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 4 mg / mL, and the amount of potassium silicate added is 0.04 g / mL.

[0058] Comparative Example 6: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 0.6g sodium carboxymethyl cellulose and 0.3g hydroxypropyl cellulose are added to 9.1g deionized water and stirred evenly. 3mL of 10wt% hydrochloric acid solution and 0.1mL epichlorohydrin are added to adjust the pH of the solution to 0.35. The solution is centrifuged to remove air bubbles, and the solution is transferred to a sealed mold. The mixture is reacted at room temperature for 1h, then frozen to -18℃ for 20h. After thawing, the mixture is washed with deionized water and freeze-dried at 40℃ for 24h to obtain a porous foam fabric.

[0059] S2: Add 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate to 150mL toluene, heat to reflux for 24h under nitrogen atmosphere, concentrate under reduced pressure, and add the product to diethyl ether to precipitate, thus obtaining functionalized polyethylene glycol.

[0060] S3: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0061] S4: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0062] S5: After cutting the porous foam fabric, a portion is immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 10wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 3 mg / mL, and the amount of potassium silicate added is 0.03 g / mL.

[0063] Comparative Example 7: A method for preparing a biodegradable medical dressing, comprising the following steps: S1: 10g polyethylene glycol, 3.57g propargyl acid, and 1.52g p-toluenesulfonic acid hydrate are added to 150mL toluene, heated to reflux under nitrogen atmosphere for 24h, concentrated under reduced pressure, and the product is added to diethyl ether to precipitate, thereby obtaining functionalized polyethylene glycol.

[0064] S2: Add 1 mmol of functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30°C and stir until homogeneous, add 3 mmol of diethanolamine, keep the reaction at this temperature for 1 h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain a polyethylene glycol precursor containing β-aminoacrylate bonds.

[0065] S3: Add 0.3 mol of polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75°C, stir until homogeneous, rinse with nitrogen to completely remove water, add 2.3 mol of diphenylmethane diisocyanate and 0.001 mol of dibutyltin dilaurate in N,N-dimethylformamide solution, heat to 75°C for 5 h under nitrogen atmosphere, add 1.52 mol of imidazolidinyl urea, keep warm for 4 h, add dry N,N-dimethylformamide, stir until homogeneous, add 0.003 mol of dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing;

[0066] S4: Commercially available PU foam fabric is cut and partially immersed in hydrogel dressing. After drying, the portion of the dried porous foam fabric containing the hydrogel dressing is immersed in a 10wt% deionized tannic acid aqueous solution. A hyaluronic acid solution containing potassium silicate is added, stirred evenly, and soaked for 4 days. After drying, a biodegradable medical dressing is obtained. The concentration of the hyaluronic acid solution is 4 mg / mL, and the amount of potassium silicate added is 0.04 g / mL.

[0067] Experiment: Photodegradation performance test: The biodegradable medical dressings prepared in Examples 1-2 and Comparative Examples 1-3 were tested using a visible light diode laser (16mW / cm²). 2 The hydrogels were subjected to photodegradation. The hydrogels were irradiated for 90 minutes. To ensure the films were fully expanded, they were soaked in water for 24 hours before irradiation.

[0068] The experimental data are shown in Table 1 below.

[0069] Table 1. Test data on the photodegradation performance of biodegradable medical dressings.

[0070] Tensile strength / kPa Fracture strain / % Young's modulus / MPa Example 1 21 31.2 0.09 Example 2 23 29.8 0.09 Comparative Example 1 478 22.9 2.58 Comparative Example 2 1233 81.2 2.49 Comparative Example 3 3679 41.8 16.13

[0071] Conclusion: The biodegradable medical dressing prepared in this invention has excellent photodegradation properties.

[0072] Comparative Example 1 used polyethylene glycol with a molecular weight of 1000, Comparative Example 2 did not add dihydroporphyrin E6, and Comparative Example 3 used polyethylene glycol with a molecular weight of 1000 without adding dihydroporphyrin E6. All of these resulted in a decrease in the photodegradability of the biodegradable medical dressing.

[0073] Free radical scavenging performance test: The free radical scavenging activity of the PTKH hydrogel was detected using the DPPH assay. Briefly, a stock solution (100 μM) of DPPH was prepared by dissolving DPPH in methanol, and then the biodegradable medical dressings from Examples 1-2 and Comparative Examples 4-6 were immersed in DPPH (50 mg / ml). After 30 minutes, the readings were taken at 517 nm using an enzyme-labeled assay.

[0074] Antibacterial performance test: Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were used as test bacteria. 1×10⁻⁶ bacteria were used. 5 A CFU / ml Luria-Bertani bacterial suspension was co-cultured with the biodegradable medical dressings of Examples 1-2 and Comparative Examples 4-6 for 24 hours. Bacterial viability was assessed by smear counting.

[0075] The experimental data are shown in Table 2 below.

[0076] Table 2. Test data on photoradical properties and antibacterial properties of biodegradable medical dressings.

[0077]

[0078] Conclusion: The biodegradable medical dressing prepared by this invention has excellent DPPH free radical scavenging and antibacterial properties.

[0079] Comparative Example 4, lacking tannic acid-silicate treatment, exhibited poor DPPH radical scavenging and no antibacterial properties, rendering its data meaningless and therefore not displayed in the table. In Comparative Example 5, the reduced tannic acid concentration, and in Comparative Example 6, the reduced silicate concentration, both resulted in decreased DPPH radical scavenging and antibacterial properties of the biodegradable medical dressing.

[0080] Blood / body fluid absorption performance test: Blood and body fluid absorption rates were tested according to the protocol described in the 1995 British Pharmacopoeia. A 5×5 cm porous foam fabric (W1) and a commercially available PU foam fabric (Example 1, Comparative Example 7) were placed in a petri dish. Blood heated to 37°C (40 times the weight of the dressing) was added. The petri dish was placed in an incubator and maintained at 37°C for 30 minutes. One corner of the test dressing was suspended with tweezers for 30 seconds, and then weighed again (W2).

[0081] Absorption rate calculation = W2 - W1 / 100cm 2

[0082] The experimental data are shown in Table 3 below.

[0083] Table 3. Blood / Body Fluid Absorption Performance Test Table for Porous Foam Fabrics

[0084] <![CDATA[Blood absorption rate / g / 100 cm 2 > <![CDATA[Humoral absorption rate / g / 100 cm 2 > Example 1 40.1 37.9 Comparative Example 7 38.7 33.6

[0085] Conclusion: The porous foam fabric prepared by this invention has excellent blood and body fluid absorption properties.

[0086] Comparative Example 7 used ordinary commercially available PU foam fabric, which lacked the hierarchical porous structure of the porous foam fabric prepared in this invention, resulting in reduced blood and body fluid absorption performance.

[0087] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a biodegradable medical dressing, characterized in that: Includes the following steps: S1: Add sodium carboxymethyl cellulose and hydroxypropyl cellulose to deionized water, stir evenly, add 10wt% hydrochloric acid solution and epichlorohydrin, adjust the pH of the solution to 0.2-0.5, centrifuge to remove air bubbles, transfer the solution to a sealed mold, react at room temperature for 1-1.5h, freeze to -20-18℃ and react for 20-22h, thaw, wash with deionized water, and dry in an environment of 40-45℃ for 24h to obtain porous foam fabric; S2: Add the polyethylene glycol precursor containing β-aminoacrylate bonds to N,N-dimethylformamide, heat to 75-80℃, stir until homogeneous, rinse with nitrogen, add diphenylmethane diisocyanate and dibutyltin dilaurate N,N-dimethylformamide solution, heat to 75-80℃ under nitrogen atmosphere and react for 5-6 hours, add imidazolidinyl urea, keep warm and react for 4-4.5 hours, add dry N,N-dimethylformamide, stir until homogeneous, add dihydroporphyrin E6, stir until homogeneous, and obtain hydrogel dressing; S3: After cutting the porous foam fabric, the fabric part is immersed in the hydrogel dressing. After drying, it is then treated with tannic acid-silicate to obtain a biodegradable medical dressing. A method for preparing a polyethylene glycol precursor containing β-aminoacrylate bonds includes the following steps: Step (1): polyethylene glycol, propargyl acid, and p-toluenesulfonic acid hydrate are added to toluene, heated to reflux for 24 hours under a nitrogen atmosphere, concentrated under reduced pressure, and the product is added to diethyl ether to precipitate, thereby obtaining functionalized polyethylene glycol. Step (2): Add functionalized polyethylene glycol to anhydrous dichloromethane, heat to 30-32℃ and stir until homogeneous, add diethanolamine, keep warm for 1-1.5h, concentrate under reduced pressure, add the product to diethyl ether to precipitate, and obtain polyethylene glycol precursor containing β-amino acrylate bonds.

2. The method for preparing a biodegradable medical dressing according to claim 1, characterized in that: In the preparation of porous foam fabric, the mass ratio of sodium carboxymethyl cellulose to hydroxypropyl cellulose is 0.6:(0.3-0.5).

3. The method for preparing a biodegradable medical dressing according to claim 1, characterized in that: In the preparation of hydrogel dressings, the molar ratio of polyethylene glycol precursor containing β-aminoacrylate bonds: diphenylmethane diisocyanate: imidazolidinyl urea: dihydroporphyrin E6 is (0.3-0.4):(2-3):(1.7-1.9):0.

003.

4. The method for preparing a biodegradable medical dressing according to claim 1, characterized in that: In the preparation of functionalized polyethylene glycol, the mass ratio of polyethylene glycol:propynic acid: p-toluenesulfonic acid hydrate is 10:(3.57-3.76):(1.52-1.55).

5. The method for preparing a biodegradable medical dressing according to claim 1, characterized in that: In the preparation of polyethylene glycol precursors containing β-aminoacrylate bonds, the molar ratio of functionalized polyethylene glycol to diethanolamine is 1:

3.

6. The method for preparing a biodegradable medical dressing according to claim 1, characterized in that: The specific process of the tannic acid-silicate treatment includes: adding tannic acid to deionized water, stirring evenly, immersing the portion of the dried porous foam fabric containing hydrogel dressing in it, adding a hyaluronic acid solution containing potassium silicate, stirring evenly, soaking for 3-4 days, and then drying.

7. The method for preparing a biodegradable medical dressing according to claim 6, characterized in that: In the tannic acid-silicate treatment process, the concentration of tannic acid added to deionized water to form a solution is 10-30 wt%; in the hyaluronic acid solution containing potassium silicate, the solvent is a hyaluronic acid solution with a concentration of 4-5 mg / mL, and the amount of potassium silicate added is 0.04-0.05 g / mL.

8. The biodegradable medical dressing prepared by the method of preparing a biodegradable medical dressing according to any one of claims 1-7.

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