Regenerated cellulose nonwoven fabric based on chitosan modification, and preparation method and application thereof

Abstract

The application discloses a regenerated cellulose non-woven fabric based on chitosan modification and a preparation method and application thereof, and comprises a non-woven fabric layer composed of regenerated cellulose fibers, wherein a gel layer formed by methacrylated chitosan and tannic acid is coated on any one side of the non-woven fabric layer, the content of the methacrylated chitosan in the gel layer is 10-30%, the content of the tannic acid is 1-30%, the grafting rate of the methacryl group in the methacrylated chitosan is 10-40%, the thickness of the gel layer is 0.1-5 mm, the antibacterial circle diameter is 1.1-1.4 cm, the equilibrium swelling rate is 110-220%, and the antioxidant rate is 60-90%. The water gel-like methacrylated chitosan coating layer is formed on the surface of the regenerated cellulose non-woven fabric, the antibacterial and antioxidant activities of the composite non-woven fabric are improved, meanwhile, the water gel-like coating layer contacts the skin wound, is beneficial to the moist healing of the wound, and can effectively inhibit the bacterial propagation and accelerate the skin wound healing. The modified non-woven fabric has excellent moisture absorption, moisture retention, antibacterial and antioxidant functions.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, and in particular to a chitosan-modified regenerated cellulose nonwoven fabric, its preparation method, and its application. Background Technology

[0002] Skin is the largest organ in the human body, and people inevitably encounter various wounds in their daily lives and work. Covering exposed wounds with dressings is a common clinical wound care method. Currently, the most widely used dressing is traditional cotton gauze, which only provides simple physical hemostasis and bandaging, leading to wounds that are prone to infection, slow to heal, and easily leave scars. However, with the development of technology and the improvement of living standards, people have placed higher demands on medical dressings. Traditional cotton gauze can no longer meet practical needs and is increasingly being replaced by new medical dressings, such as functional non-woven dressings containing antibacterial components such as chitosan and silver particles, which have been extensively studied. Because ordinary dressings tend to stick to the wound when it is changed after scabbing, causing secondary injury to the patient and slowing down the healing process. In 1962, the British scientist Winter pointed out that wounds heal more easily in a moist environment, the famous "moist wound healing theory," which has further advanced wound care techniques.

[0003] Regenerated cellulose nonwoven fabrics have significant applications in textiles, cosmetics, and medicine. In the pharmaceutical field, regenerated cellulose nonwoven fabrics, as traditional dressings, play a role in protecting wounds and absorbing wound exudate; however, they are prone to adhering to wounds, causing secondary skin damage, which limits their clinical application. Chitosan and its derivatives, with their biodegradability, good biocompatibility, antibacterial, and hemostatic properties, have attracted widespread attention in the field of medical tissue engineering. Currently, there is considerable research on chitosan / viscose spunlace nonwoven fabrics, but the moisture absorption, moisturizing, antibacterial, and antioxidant properties of these composite nonwoven fabrics are unsatisfactory.

[0004] CN 105079861 A describes a preparation process for a modified chitosan composite gel moisturizing adhesive bandage, wherein the adhesive bandage comprises, from bottom to top, a non-woven fabric layer, a moisturizing layer, and a protective layer, wherein the moisturizing layer is composed of a modified chitosan composite gel. The preparation process describes a method for preparing the adhesive bandage.

[0005] CN 109627462 A discloses a method for preparing a high-strength methacrylamide chitosan hydrogel, which is implemented according to the following steps: First, chitosan is dissolved in a solvent, methacrylic anhydride is added to obtain a methacrylamide chitosan solution, which is then dialyzed in a dialysis bag, freeze-dried, and refrigerated. After that, the methacrylamide chitosan is dissolved in water, acrylamide F127 is added, a photoinitiator is added to the mixture, and the mixture is stirred evenly. The hydrogel is prepared by crosslinking with 5-10W UV light to obtain a high-strength chitosan hydrogel.

[0006] CN 115814149 A discloses a modified carboxymethyl chitosan hemostatic material and its preparation method. The preparation steps include: firstly, carboxymethylating chitosan fibers to obtain carboxymethyl chitosan fibers, and then modifying the carboxymethylated chitosan fibers by introducing kaolin and Ca2+, or a combination of the two, to prepare a kaolin and / or Ca2+ modified carboxymethyl chitosan hemostatic material.

[0007] CN 112891607A discloses an anti-infective and anti-adhesion modified chitosan hemostatic dressing, which consists of a rapid hemostatic layer, an antibacterial composite layer, and an outer protective layer, arranged sequentially from the wound surface. The rapid hemostatic layer is a modified chitosan gel film that adsorbs calcium ions. The antibacterial composite layer is an alginate / sweet potato starch composite film loaded with organo-attapulgite microspheres. The outer protective layer is made by grafting chitosan onto non-woven fabric or absorbent cotton. The rapid hemostatic layer, the antibacterial composite layer, and the outer protective layer are connected together through physicochemical reactions. This invention also provides a method for preparing the anti-infective and anti-adhesion modified chitosan hemostatic dressing.

[0008] As can be seen from the aforementioned patented technologies, chitosan derivatives with certain functional groups can be obtained through chemical modification. Chemically modified chitosan exhibits improved water solubility, moisturizing properties, and antibacterial properties compared to traditional chitosan, expanding its applications. However, simply modifying chitosan alone cannot achieve the moisture-absorbing, moisturizing, antibacterial, and antioxidant properties required for skin wounds. Other hemostatic, antibacterial, and healing-promoting components need to be added to realize these functions, increasing production costs. Furthermore, wound dressings primarily rely on non-woven fabrics as the substrate. While antibacterial drugs exert their effects, the relationship between the substrate and the antibacterial drug also affects wound healing. Drug exudation and its ability to concentrate on the skin wound are also crucial factors in wound repair and healing. Therefore, current medical hydrogels and dressings containing modified chitosan cannot truly achieve the goals of wound protection, absorption of wound exudate, prevention of wound adhesion, and avoidance of secondary skin damage, thus limiting their practical clinical application. In conclusion, how to make nonwoven fabrics possess antibacterial, moisture-absorbing, moisture-retaining, anti-adhesion, and antioxidant properties that promote wound healing has become a pressing problem for those skilled in the art. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide a chitosan-modified regenerated cellulose nonwoven fabric that improves the antibacterial and antioxidant activity of nonwoven fabrics, promotes moist wound healing, effectively inhibits bacterial growth, and accelerates skin wound healing, as well as its preparation method and application.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a chitosan-modified regenerated cellulose nonwoven fabric, comprising a nonwoven fabric layer composed of regenerated cellulose fibers, characterized in that: a gel layer formed by methacrylamide chitosan and tannic acid is coated on any side of the nonwoven fabric layer, wherein the content of methacrylamide chitosan in the gel layer is 10-30%, the content of tannic acid is 1-30%, the grafting rate of methacrylamide groups in the methacrylamide chitosan is 10-40%, the thickness of the gel layer is 0.1-5 mm, the antibacterial rate is 70-95%, the equilibrium swelling rate is 110-220%, and the antioxidant rate is 60-90%.

[0011] The above-mentioned chitosan-modified regenerated cellulose nonwoven fabric has a gel layer containing 30% methacrylated chitosan, 10% tannic acid, and a gel layer thickness of 5 mm.

[0012] The aforementioned chitosan-modified regenerated cellulose nonwoven fabric has a methacrylamide grafting rate of 30% in the methacrylamide chitosan.

[0013] The aforementioned chitosan-modified regenerated cellulose nonwoven fabric has a nonwoven layer thickness of 0.1-5 mm, an antibacterial rate of 95% against Staphylococcus aureus, an equilibrium swelling rate of 220%, and an antioxidant rate of 90%.

[0014] The aforementioned chitosan-modified regenerated cellulose nonwoven fabric includes any one or more of viscose fiber, modal fiber, lyocell fiber, cellulose fiber, and lyocell fiber.

[0015] A method for preparing chitosan-modified regenerated cellulose nonwoven fabric includes the following steps:

[0016] I. Chitosan Modification:

[0017] (1) Dissolve a certain amount of chitosan in acetic acid solution to form a chitosan solution, and add a certain amount of methacrylic anhydride dropwise to the chitosan solution.

[0018] (2) Neutralize the chitosan solution with sodium bicarbonate solution and dilute it. Dialyze it with deionized water to remove unreacted reagents and obtain a chitosan solution with double bond modification.

[0019] (3) Freeze-dry the chitosan solution to obtain methacrylated chitosan with a methacrylyl grafting rate of 10-40%;

[0020] II. Crosslinking treatment:

[0021] (4) Prepare a tannic acid solution with a concentration of 0.5-5%, and immerse the regenerated cellulose nonwoven fabric in the solution for 1-10 minutes. After immersion, place it in a template.

[0022] (5) Prepare a mixed solution containing methacrylamide chitosan and Ig2959 photoinitiator, wherein the mass ratio of methacrylamide chitosan to Ig2959 photoinitiator is 20:(1-10);

[0023] (6) Quickly and evenly coat the surface of the regenerated cellulose nonwoven fabric with the mixed solution;

[0024] (7) Under ultraviolet light, the light intensity of the ultraviolet light is 10-200W and the light time is 1-10min. The mixed solution simultaneously undergoes photocrosslinking and tannic acid crosslinking reaction on the surface of the regenerated cellulose nonwoven fabric to form a gel layer, thereby obtaining the chitosan-modified regenerated cellulose nonwoven fabric.

[0025] In the above-mentioned method for preparing chitosan-modified regenerated cellulose nonwoven fabric, in step (4), the tannic acid solution is prepared by tannic acid and 75% ethanol solution with a concentration of 2%, and the treatment time for impregnating the regenerated cellulose nonwoven fabric is 5 min.

[0026] In the above-mentioned method for preparing regenerated cellulose nonwoven fabric based on chitosan modification, in step (5), the mass ratio of methacrylated chitosan to Ig2959 photoinitiator is 5:1.

[0027] In step (7) of the above-mentioned method for preparing chitosan-modified regenerated cellulose nonwoven fabric, the ultraviolet light intensity is 100W and the irradiation time is 2min.

[0028] Application of chitosan-modified regenerated cellulose nonwoven fabric in medical dressings for skin wounds.

[0029] The advantages of this invention, based on chitosan-modified regenerated cellulose nonwoven fabric, its preparation method, and its application, are as follows: Compared with existing technologies, this invention utilizes chemical and photocrosslinking technologies, combined with tannic acid crosslinking technology, to simultaneously crosslink the regenerated cellulose fiber nonwoven fabric. By combining the regenerated cellulose nonwoven fabric with a gel coating, and employing methacryloyl chitosan photocrosslinking and tannic acid crosslinking methods, a gel layer with a thickness of approximately 0.1-5.0 mm is formed. This creates a hydrogel-like methacryloyl chitosan coating on the surface of the regenerated cellulose nonwoven fabric, enhancing the antibacterial and antioxidant activity of the composite nonwoven fabric. Simultaneously, the hydrogel-like coating, upon contact with skin wounds, promotes moist wound healing and effectively inhibits bacterial growth and accelerates skin wound healing. The modified nonwoven fabric exhibits excellent moisture absorption, moisture retention, and antibacterial and antioxidant functions. The preparation method is simple and easy to implement. The prepared methacryloylchitosan-modified regenerated cellulose nonwoven fabric has an antibacterial rate of ≥90%, good biocompatibility, degradability, antibacterial properties, and mechanical properties. It has antibacterial and anti-inflammatory characteristics, does not adhere to wounds, and provides a moist environment for wounds, both absorbing and effectively moisturizing, thus accelerating wound healing. It can be applied in the field of wound dressing technology. Attached Figure Description

[0030] Figure 1 These are photographs of the actual product of the present invention;

[0031] Figure 2 SEM image of unmodified viscose fiber nonwoven fabric;

[0032] Figure 3 This is a SEM image of the methacryloyl chitosan-modified viscose fiber nonwoven fabric from Example 1 of the present invention.

[0033] Figure 4 This is a comparison photo of Embodiment 2 of the present invention and the antibacterial ring of unmodified viscose fiber nonwoven fabric. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] (1) Preparation of methacrylamide chitosan: Take 1g of chitosan (molecular weight 200,000, degree of deacetylation 85%), dissolve it in 100mL of 2% acetic acid solution, add 3mL of methacrylic anhydride dropwise to the above chitosan solution, and react at 60℃ for 6 hours. The resulting solution is neutralized with sodium bicarbonate solution and diluted to terminate the reaction. Dialyze with deionized water to remove unreacted reagents. After freeze-drying, methacrylamide chitosan is obtained with a methacrylamide grafting rate of 30%.

[0037] (2) Take 0.25g of tannic acid and dissolve it in 50mL of 75% ethanol solution to obtain a 0.5% tannic acid solution. Use the above solution to impregnate the viscose nonwoven fabric, soak it for 2 minutes, and then place it in the template.

[0038] (3) Take 1g of the prepared methacrylamide chitosan and dissolve it in 100mL of deionized water to obtain a 1% methacrylamide chitosan solution. Add 0.05g of Ig2959 photoinitiator to the methacrylamide chitosan solution and stir evenly. Coat the mixed solution evenly on the surface of the nonwoven fabric, with a gel layer thickness of about 0.1mm. Irradiate under 50W ultraviolet light for 1min to obtain methacrylamide chitosan modified viscose nonwoven fabric. Figure 1 As shown, its SEM morphology is as follows Figure 3 As shown in the figure. Measurements revealed that the nonwoven fabric contained approximately 1% tannic acid and 10% methacrylamide chitosan. The modified nonwoven fabric had an equilibrium swelling rate of approximately 120%; an inhibition zone diameter of 1.1 cm; and an inhibition rate of 75% against Staphylococcus aureus. The antioxidant rate of the modified nonwoven fabric, determined by the DPPH method, was 65%. The relative molecular weight of chitosan in the methacrylamide chitosan was 200,000-2,000,000, and the degree of deacetylation was 85%.

[0039] Example 2:

[0040] (1) Preparation of methacrylated chitosan: Same as step (1) in Example 1.

[0041] (2) Take 1g of tannic acid and dissolve it in 50mL of 75% ethanol solution to obtain a 2% tannic acid solution. Use the above solution to impregnate the viscose nonwoven fabric, soak it for 5 minutes, and then place it in the template.

[0042] (3) Take 1g of methacrylated chitosan and dissolve it in 100mL of deionized water to obtain a 1% methacrylated chitosan solution. Add 0.2g of Ig2959 photoinitiator and stir evenly. Coat the mixed solution evenly on the surface of the nonwoven fabric, with a gel thickness of about 5mm. Irradiate under 100W ultraviolet light for 2min to obtain methacrylated chitosan modified viscose nonwoven fabric. Its SEM morphology is as follows: Figure 4 As shown in the figure. The tannic acid content was determined to be approximately 10%, and the methacrylamide chitosan content was 30%. The modified nonwoven fabric had an equilibrium swelling rate of 220%, an inhibition zone diameter of 1.4 cm, an inhibition rate of 95% against Staphylococcus aureus, and an antioxidant rate of 90% as determined by the DPPH method.

[0043] Example 3:

[0044] (1) Preparation of methacrylated chitosan: Same as step (1) in Example 1.

[0045] (2) Take 5g of tannic acid and dissolve it in 50mL of 75% ethanol solution to obtain a 5% tannic acid solution. Use the above solution to impregnate the modal nonwoven fabric. After soaking for 5 minutes, place it in a template.

[0046] (3) Take 1g of methacrylamide chitosan and dissolve it in 100mL of deionized water to obtain a 1% methacrylamide chitosan solution. Add 0.5g of Ig2959 photoinitiator and stir evenly. Quickly and evenly coat the mixed solution onto the surface of the nonwoven fabric and irradiate it under 100W ultraviolet light for 10min to obtain methacrylamide chitosan modified modal nonwoven fabric with a gel thickness of about 2.5mm. The content of tannic acid in the fabric is about 30%, and the content of methacrylamide chitosan is about 20%. The equilibrium swelling rate of the modified nonwoven fabric is 150%, the diameter of the inhibition zone is 1.2cm, the inhibition rate against Staphylococcus aureus is 95%, and the antioxidant rate of the modified nonwoven fabric is 90% as determined by the DPPH method.

[0047] Example 4:

[0048] (1) Preparation of methacrylamide chitosan: Take 1g of chitosan (molecular weight 200,000, degree of deacetylation 85%), dissolve it in 100mL of 2% acetic acid solution, add 4mL of methacrylic anhydride dropwise to the above chitosan solution, and react at 60℃ for 8 hours. The resulting solution is neutralized with sodium bicarbonate solution to terminate the reaction. Dialyze with deionized water to remove unreacted reagents. After freeze-drying, methacrylamide chitosan is obtained with a methacrylamide grafting rate of 40%.

[0049] (2) Take 0.25g of tannic acid and dissolve it in 50mL of 75% ethanol solution to obtain a 0.5% tannic acid solution. Use the above solution to impregnate the modal nonwoven fabric, soak it for 10min and then place it in the template.

[0050] (3) Take 1g of methacrylamide chitosan, dissolve it in 100mL of deionized water to prepare a 1% methacrylamide chitosan solution, add 0.05g of Ig2959 photoinitiator, stir evenly, and quickly and evenly coat the mixed solution onto the surface of the nonwoven fabric. The gel thickness is about 0.1mm. Irradiate under 10W ultraviolet light for 10min to obtain methacrylamide chitosan modified modal nonwoven fabric. It was determined that the tannic acid content in the nonwoven fabric was about 3%, and the methacrylamide chitosan content was 15%. The equilibrium swelling rate of the modified nonwoven fabric was 130%, the diameter of the inhibition zone was 1.1cm, the inhibition rate against Staphylococcus aureus was 85%, and the antioxidant rate after DPPH solution testing was 88%.

[0051] Example 5:

[0052] (1) Preparation of methacrylated chitosan: Same as step (1) in Example 1.

[0053] (2) Take 2g of tannic acid and dissolve it in 100mL of 75% ethanol to obtain a 2% tannic acid solution. Use the above solution to impregnate Lyocell nonwoven fabric, soak for 10 minutes, and then place it in a template.

[0054] (3) Take 1g of methacrylamide chitosan and dissolve it in 100mL of deionized water to obtain a 1% methacrylamide chitosan solution. Add 0.1g of Ig2959 photoinitiator and stir evenly. Quickly and evenly coat the mixed solution onto the surface of the nonwoven fabric, with a gel thickness of about 2mm. Irradiate under 200W ultraviolet light for 1min to obtain methacrylamide chitosan modified lyocell nonwoven fabric. The tannic acid content was determined to be about 30%, and the methacrylamide chitosan content was 25%. The equilibrium swelling rate of the modified nonwoven fabric was 150%, the diameter of the inhibition zone was 1.2cm, the inhibition rate against Staphylococcus aureus was 90%, and the antioxidant rate after DPPH solution testing was 90%.

[0055] Example 6:

[0056] (1) Preparation of methacrylated chitosan: Take 1g of chitosan (molecular weight 2 million), dissolve it in 10mL of 0.5% acetic acid solution, add 3mL of methacrylic anhydride dropwise to the above chitosan solution, and react at 60℃ for 3 hours. After post-treatment, the grafting rate of methacryl groups is 10%.

[0057] (2) Take 2g of tannic acid and dissolve it in 100mL of 75% ethanol to obtain a 2% tannic acid solution. Use the above solution to impregnate the viscose nonwoven fabric, soak it for 1 minute, and then place it in the template.

[0058] (3) Take 1g of methacrylamide chitosan and dissolve it in 100mL of deionized water to obtain a 1% methacrylamide chitosan solution. Add 0.1g of Ig2959 photoinitiator, stir evenly, and coat the mixed solution evenly on the surface of the nonwoven fabric. The gel thickness is about 1mm. Irradiate under 200W ultraviolet light for 1min to obtain methacrylamide chitosan modified viscose nonwoven fabric. It was determined that its tannic acid content is about 1% and its methacrylamide chitosan content is about 10%. The equilibrium swelling rate of the modified nonwoven fabric is 110%, the diameter of the inhibition zone is 1.1cm, the inhibition rate against Staphylococcus aureus is 60%, and the antioxidant rate after DPPH solution testing is 70%.

[0059] Depend on Figure 2 , 3 The comparison shows that, Figure 2 This is an unmodified viscose fiber nonwoven fabric; the fiber surface before modification has obvious grooves. Figure 3 The modified fiber surface became smooth and the fiber diameter became thicker, indicating the formation of a gel layer on the surface of the nonwoven fabric.

[0060] Depend on Figure 4 It can be seen that the diameter of the antibacterial ring of the unmodified viscose fiber nonwoven fabric is basically 0, while the diameter of the antibacterial ring after modification in Example 2 of this invention is about 1.4 cm, indicating that the modified regenerated cellulose nonwoven fabric has excellent antibacterial properties.

[0061] Performance test results of the methacryloylchitosan-modified regenerated cellulose nonwoven fabric of this invention:

[0062]

[0063] illustrate:

[0064] MA stands for methyl methacryloyl group;

[0065] TA is tannic acid;

[0066] CSMA is methacrylamide chitosan.

[0067] As shown in the table above, the methacrylyl grafting rate, tannic acid content, methacrylated chitosan content, and swelling rate play important roles in antibacterial properties, hygroscopicity, moisturizing, anti-adhesion, and antioxidant properties, promoting wound healing. A high methacrylyl grafting rate affects the tannic acid content, leading to poor antibacterial effects. Conversely, a low methacrylyl grafting rate results in insufficient acrylate double bonds grafted onto the chitosan molecules, affecting the stability of the three-dimensional network structure during photocrosslinking, leading to poor wet stability of the hydrogel, poor water absorption and release, and easy loss of chitosan components. Low photoinitiator and methacrylated chitosan content also easily lead to poor photocrosslinking hydrogel effects. Therefore, an optimal ratio of methacrylyl grafting rate, tannic acid content, photoinitiator ratio, and methacrylated chitosan content is required. Therefore, Example 2 of this invention represents the best results.

[0068] A comparison of Examples 1, 2, and 3 shows that, with the same percentage of methacryloyl grafting, the higher the proportion of photoinitiator, the higher the percentage of methacryloyl chitosan, and the higher the swelling rate, antioxidant rate, inhibition zone diameter, and antibacterial rate.

[0069] As can be seen from the comparison of Examples 4 and 5, when the percentage of methacryloyl grafting is the same, the higher the tannic acid content, the higher the antioxidant rate, the diameter of the inhibition zone and the antibacterial rate. Therefore, the tannic acid content determines the antibacterial effect of the hydrogel.

[0070] A comparison of Examples 1 and 2 shows that, with the same percentage of methacrylamide grafting, higher tannic acid content, photoinitiator ratio, and methacrylamide chitosan content result in higher swelling rate, antioxidant rate, inhibition zone diameter, and antibacterial rate. The antioxidant rate is related to tannic acid concentration, tannic acid soaking time, tannic acid content, UV irradiation time (crosslinking time), photoinitiator ratio, methacrylamide chitosan content, and gel layer thickness.

[0071] As can be seen from the comparison of Examples 3 and 5, when the tannic acid content is the same, the methacryloyl grafting rate is 30-40%, and the photoinitiator ratio has little effect on the final effect. It can be seen that the tannic acid content and the methacryloyl grafting rate play a key role in the present invention.

[0072] As can be seen from the comparison of Examples 2 and 3, the swelling rate is directly related to the thickness of the gel layer, and has little to do with other factors.

[0073] In the chitosan modification process of this invention, glycidyl methacrylate can also be used instead of methacrylic anhydride. Glycidyl methacrylate or methacrylic anhydride can undergo a substitution reaction with the amino groups on chitosan, grafting acrylate double bonds into the chitosan molecule. Under the action of a photoinitiator, a photocrosslinking reaction is carried out by ultraviolet light irradiation. The carbon-carbon double bonds in the polymer network are further crosslinked to form a hydrogel. The hydrogel has a stable three-dimensional network structure, which improves the mechanical strength of the gel layer.

[0074] This invention employs a "dual-network crosslinking" concept: simultaneously with photocrosslinking to form a hydrogel, tannic acid undergoes a substitution reaction with the active amino and hydroxyl groups in the modified chitosan molecules, resulting in the grafting of a certain amount of tannic acid into the modified chitosan molecules, forming a "composite" modified chitosan molecular structure. Several "composite" modified chitosan molecules crosslink to form a three-dimensional network structure hydrogel. This "composite" modified chitosan molecule structure allows tannic acid to exist stably within the three-dimensional network gel, achieving a long-lasting antibacterial effect. Simultaneously, the high antioxidant rate of tannic acid effectively inhibits free radicals in the wound, accelerating wound healing. A high equilibrium swelling rate enables the gel layer to provide long-lasting moisture absorption and hydration to the wound, while also preventing adhesion.

[0075] As another innovation of this invention, while photocrosslinking and tannic acid crosslinking occur, the active groups in tannic acid and modified chitosan molecules, such as amino and hydroxyl groups, can further combine with the cellulose fibers in the nonwoven fabric layer through hydrogen bonding, thereby enhancing the interaction between the gel layer and the nonwoven fabric layer and improving the stability of the gel layer's adhesion to the surface of the nonwoven fabric layer. This results in excellent performance in terms of antibacterial properties, moisture absorption, moisturizing, anti-adhesion, and antioxidant properties that promote wound healing.

[0076] 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 its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of protection of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0077] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A chitosan-modified regenerated cellulose nonwoven fabric, comprising a nonwoven layer composed of regenerated cellulose fibers, characterized in that: A gel layer formed by methacrylamide chitosan and tannic acid is coated on any side of a nonwoven fabric layer. The gel layer contains 30% methacrylamide chitosan and 10% tannic acid. The grafting rate of methacrylamide groups in the methacrylamide chitosan is 30%. The thickness of the gel layer is 5 mm. It exhibits a 95% inhibition rate against Staphylococcus aureus, a 220% equilibrium swelling rate, and a 90% antioxidant rate. The preparation method includes the following steps: I. Chitosan Modification: (1) Dissolve a certain amount of chitosan in acetic acid solution to form a chitosan solution, and add a certain amount of methacrylic anhydride dropwise to the chitosan solution; (2) Neutralize the chitosan solution with sodium bicarbonate solution and dilute it. Dialyze it with deionized water to remove unreacted reagents and obtain a chitosan solution with double bond modification. (3) Freeze-dry the chitosan solution to obtain methacrylated chitosan with a methacrylyl grafting rate of 10-40%; II. Crosslinking treatment: (4) Prepare a 2% tannic acid solution by mixing tannic acid with 75% ethanol solution. Take regenerated cellulose nonwoven fabric and immerse it in the solution for 5 minutes. After immersion, place it in a template. (5) Prepare a mixed solution containing methacrylamide chitosan and Ig2959 photoinitiator, wherein the mass ratio of methacrylamide chitosan to Ig2959 photoinitiator is 5:1; (6) Quickly and evenly coat the surface of the regenerated cellulose nonwoven fabric with the mixed solution; (7) Under ultraviolet light, the light intensity is 100W and the light time is 2min. The mixed solution simultaneously undergoes photocrosslinking and tannic acid crosslinking reaction on the surface of the regenerated cellulose nonwoven fabric to form a gel layer, thereby obtaining the chitosan-modified regenerated cellulose nonwoven fabric.

2. The chitosan-modified regenerated cellulose nonwoven fabric according to claim 1, characterized in that: The regenerated cellulose fiber includes any one or more of viscose fiber, modal fiber, lyocell fiber, cellulose fiber, and lyocell fiber.

3. The application of chitosan-modified regenerated cellulose nonwoven fabric as described in any one of claims 1-2 in the preparation of medical dressings for skin wounds.

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