Preparation method and application of high-efficiency emergency antibacterial dressing

Abstract

The application provides a preparation method and application of a high-efficiency emergency antibacterial dressing and belongs to the technical field of biomedical materials. The high-efficiency emergency antibacterial dressing is prepared through a systematic process of alcohol-free wet spinning, secondary traction stretching, vacuum freeze drying, semi-dry state rapid carboxymethylation and needle punching / water jetting into cloth. The high-efficiency emergency antibacterial dressing has high mechanical strength and strong liquid absorption capacity, can absorb a large amount of wound exudate and keep the wound moist, and realizes the synergistic effect of multiple functions such as emergency, anti-adhesion, strong stability, antibiosis and repair promotion.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a method for preparing and applying a highly efficient emergency antibacterial dressing. Background Technology

[0002] Skin wounds are injuries caused by accidents or trauma, which can severely impact an individual's daily activities and work capacity. Using appropriate wound dressings can accelerate healing and reduce the risk of infection. Ideal wound dressings should be non-toxic, have appropriate gas permeability, excellent mechanical properties, strong biocompatibility, and rapid wound healing, while also providing some pain relief, improving the patient's quality of life, and preventing secondary injuries.

[0003] Currently, commonly used wound dressings include traditional dressings, natural polysaccharide dressings, and synthetic dressings, all of which have a series of problems in application. Traditional dressings (such as gauze, cotton pads, and petroleum jelly gauze) are limited by the raw materials themselves, resulting in a simple structure and function. They rely solely on simple fiber stacking to achieve basic absorption and protection, failing to maintain a stable moist microenvironment on the wound surface. After drying, the fibers easily embed into the newly formed wound, causing adhesion and damage. Traditional dressings have large mesh pores, lack inherent antibacterial and anti-inflammatory capabilities, and have poor pore controllability, making it difficult to block the invasion of exogenous bacteria. Furthermore, traditional dressings have low absorbency and are prone to side leakage. While natural polysaccharide dressings (such as alginate) possess excellent moisture-absorbing gel properties, their original molecular chain cross-linking stability is insufficient, and their molding process is simple and crude, without modification, reinforcement, or structural optimization. In a wet state, the overall network is easily broken and disintegrates, resulting in poor support. While synthetic dressings (such as hydrocolloids, alginates, foams, and films) optimize absorbency and adhesion, their molecular structure design focuses only on single needs of breathability or liquid retention, lacking bioactive sites that promote cell proliferation and regulate inflammatory responses. They mostly rely on added silver ions and antibiotics to achieve antibacterial effects, which can easily lead to cytotoxicity and drug resistance. At the same time, the cross-linked structure of the polymer itself makes it difficult to balance wet mechanical strength and breathability after high absorbency. After absorbing liquid, they are prone to excessive water loss and hardening, expansion and compression of the wound, or local fluid accumulation and skin maceration. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a highly efficient emergency antibacterial dressing. This invention employs a semi-dry rapid carboxymethylation modification process to modify chitosan, introducing hydrophilic carboxyl and hydroxyl groups into its molecular chain. This effectively solves the defects of chitosan, such as poor water solubility, acidic solubility, and strong irritation, endowing the material with excellent water-soluble swelling and gelling properties. Upon contact with wound exudate, it rapidly forms a flexible, moisturizing gel layer, stably constructing a moist healing microenvironment, achieving self-dissolving debridement, and isolating external bacteria. Antibacterial properties are achieved through the charge adsorption of the inherent amino and carboxyl groups in the molecular chain, regulating the expression of inflammatory factors and promoting fibroblast proliferation and angiogenesis to accelerate wound repair and reduce scar formation. Combined with acupuncture and hydroentangling processes... The three-dimensional porous nonwoven fabric structure has highly porous channels that can quickly absorb and lock in exudate and prevent skin maceration. The fiber entanglement greatly improves wet strength, combining the advantages of soft and conformable hydroentanglement and strong support of needle punch. The gel isolation layer avoids dressing adhesion to the wound and secondary damage during dressing changes. It avoids the risks of drug resistance and cytotoxicity without the need to add antibacterial adjuvants. At the same time, the material is biocompatible and completely degradable. From the dual dimensions of molecular activity optimization and macroscopic structure regulation, it comprehensively solves various drawbacks of traditional gauze drying and adhesion, single function and mechanical and breathable imbalance of synthetic dressings, insufficient wet strength of conventional synthetic dressings, and difficulty in matching the dynamic healing needs of wounds.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a highly efficient emergency antibacterial dressing, comprising the following steps:

[0007] Step S1: Preparation of spinning solution:

[0008] Chitosan spinning solution was prepared using aqueous acetic acid solution as solvent.

[0009] Further, the preparation method of the chitosan spinning solution is as follows: Chitosan is dissolved in an aqueous acetic acid solution with a mass fraction of 0.5%-5%, stirred at 15-35 °C for 2-6 h until completely dissolved, and then degassed under vacuum (0.05-0.8 MPa) for 5-120 min to obtain a chitosan spinning solution with a mass fraction of 3%-6%. In the preparation process of the chitosan spinning solution, acetic acid provides H₂. + It can protonate the amino groups of chitosan, break the hydrogen bonds between molecules, and promote dissolution; degassing treatment can prevent filament breakage caused by air bubbles during spinning.

[0010] Step S2: Alcohol-free wet spinning and secondary traction stretching:

[0011] The chitosan spinning solution is extruded into a first coagulation bath for primary drawing; then placed in a second coagulation bath for secondary drawing to obtain nascent fibers; wherein, the first coagulation bath is a mixed solution of sodium hydroxide and sodium sulfate, and the second coagulation bath is a sodium sulfate solution; the present invention uses an alcohol-free system and significantly improves the orientation degree of fiber macromolecules through secondary drawing, significantly enhancing breaking strength and flexibility; specifically, the above-mentioned dual coagulation baths enable the outer layer of the fiber to first solidify to form a skin layer, while the inner layer continues to diffuse and solidify, and the drawing process causes the molecular chains to align along the axial direction, improving crystallinity and mechanical properties, and solving the problem that traditional alcohol coagulation baths easily produce solvent residues that affect biocompatibility. The sodium hydroxide in the first coagulation bath directly determines the coagulation rate and deprotonation degree from the fiber surface to the interior. Therefore, this invention controls the concentration of sodium hydroxide in the first coagulation bath to 1.5%-3.5%. Excessive sodium hydroxide concentration can easily lead to cracking of the fiber skin-core structure, while excessively low concentrations will result in insufficient coagulation and failure to form the desired shape. Sodium sulfate, as a neutral salt, mainly regulates the ionic strength and dehydration rate of the first coagulation bath through the salting-out effect. Appropriately increasing its concentration helps accelerate the aggregation and solidification of chitosan molecular chains, but excessive concentration will cause overly vigorous coagulation and surface defects in the fiber. The concentration of sodium sulfate in the second coagulation bath is significantly higher than that in the first coagulation bath. It can further enhance fiber dehydration and structural densification while ensuring the stability of the first coagulation bath, promoting the rearrangement of the hydrogen bond network and the perfection of the crystal regions.

[0012] Furthermore, the chitosan spinning solution is extruded through a spinneret with an aperture of 0.05-1.0 mm.

[0013] Furthermore, in the first coagulation bath, the mass fraction of sodium hydroxide is 1.5%-3.5%, and the mass fraction of sodium sulfate is 3%-4%.

[0014] Furthermore, the first-stage draw ratio is 1-1.3 times.

[0015] Furthermore, in the second coagulation bath, the mass fraction of sodium sulfate is 8%-15%.

[0016] Furthermore, the secondary draw ratio is 1.3-1.7 times.

[0017] Furthermore, the fineness of the nascent fibers is 0.8-1.5 dtex.

[0018] Step S3: Washing and drying:

[0019] The nascent fibers were washed until neutral and then freeze-dried under vacuum to obtain chitosan fiber bundles.

[0020] Further, the procedure for washing the nascent fibers to neutral is as follows: the fiber bundle is dynamically countercurrently washed with deionized water at 30-60 ℃ for 3-5 times, each time for 5-10 minutes, until neutral.

[0021] Further, the vacuum freeze-drying operation is as follows: the fiber bundle is pre-frozen at -30 to -10 °C for 1-3 h, with the vacuum controlled at 100-150 Pa; then, the temperature is gradually increased to 30-50 °C over 1-3 h, and then further increased to 60-80 °C over 0.5-2 h, while maintaining a vacuum of 50-300 Pa, until the fiber temperature reaches 10-25 °C and the pressure inside the chamber stabilizes at 10-50 Pa. This invention, through vacuum freezing combined with gradient temperature drying, allows ice crystals to sublimate, leaving continuous channels and forming a porous framework, which is beneficial for reagent molecule diffusion and the exposure of binding sites.

[0022] Step S4: Semi-dry rapid carboxymethylation modification:

[0023] The chitosan fiber bundles were immersed in a first sodium hydroxide solution for treatment, and then centrifuged to dry, resulting in alkalized fibers.

[0024] The alkalized fiber and sodium chloroacetate were mixed at a dry weight ratio of 1:(1.2-1.5), and isopropanol (the mass ratio of isopropanol to sodium chloroacetate was (1.5-3):1) was added to make a paste, thus obtaining a paste.

[0025] Add the second sodium hydroxide solution to the paste and mix quickly and evenly to obtain a semi-dry etherified product;

[0026] The semi-dry etherified compound was thoroughly kneaded and mixed, and then reacted at 65-85 °C for 4-6 h.

[0027] Wash and dry to obtain carboxymethyl chitosan fiber bundles.

[0028] Furthermore, the mass concentration of the first sodium hydroxide solution is 8%-12%; in the second sodium hydroxide solution, the mass ratio of sodium hydroxide to water is 1:2.

[0029] Step S5: Weaving into fabric:

[0030] The carboxymethyl chitosan fiber bundles are woven into fabric to obtain a highly efficient emergency antibacterial dressing.

[0031] Further, the operation of weaving the carboxymethyl chitosan fiber bundles into fabric is as follows: the carboxymethyl chitosan fiber bundles are cut into short fibers of 3-6 cm, combed into a web, and prepared into carboxymethyl chitosan nonwoven fabric (G-cloth), needle-punched fabric (Z-cloth) and hydroentangling fabric (W-cloth) by needle punching machine (forward punching + reverse punching) and hydroentangling machine (high pressure micro water jet).

[0032] This invention achieves structural regulation, chemical modification, and molding reinforcement of chitosan fiber bundles through the synergistic effects of two-stage traction stretching, semi-dry etherification modification, and needle punching / hydraulic composite reinforcement. Specifically, the two-stage traction stretching precisely controls the fiber orientation and crystallinity, creating a uniform and controllable reaction interface for the semi-dry etherification reaction, allowing carboxymethyl groups to be uniformly grafted along the fiber axis. Simultaneously, it avoids the damage to processing performance caused by excessive water solubility. The highly oriented fiber structure improves the mechanical strength and tear resistance of the nonwoven fabric in both dry and wet states, enabling the final dressing to maintain good structural integrity while absorbing a large amount of exudate and maintaining a moist healing environment. The principle of the semi-dry rapid carboxymethylation modification used in this invention is as follows: First, the chitosan fiber bundles are pretreated with a strong base (NaOH) to activate the reactive hydroxyl groups on their molecular chains. Then, in a solid or semi-solid medium, a nucleophilic substitution reaction occurs between the etherification reagent and the activated hydroxyl groups, thereby introducing highly hydrophilic carboxymethyl groups onto the macromolecular backbone of the chitosan fiber bundles. Compared to traditional carboxymethylation modification, the semi-dry rapid carboxymethylation modification process has the following advantages: the limited moisture environment effectively inhibits the hydrolysis side reaction of the etherifying agent, significantly improving the yield of the substitution reaction; on the other hand, this process avoids the irreversible damage to the fiber crystalline structure caused by excessive swelling or dissolution, while endowing nonwoven fabrics with functional characteristics such as high liquid absorption rate, excellent moisture retention and physiological environmental responsiveness, and maximally preserving the original morphological integrity and mechanical network structure of the fiber, thereby improving the structural uniformity, liquid absorption kinetics and macroscopic mechanical properties of the product.

[0033] Secondly, the present invention provides a highly efficient emergency antibacterial dressing prepared using the aforementioned preparation method.

[0034] Thirdly, the present invention provides the application of the aforementioned high-efficiency emergency antibacterial dressing in the preparation of medical materials.

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] The high-efficiency emergency antibacterial dressing of this invention is significantly different from existing technologies through a systematic process of "alcohol-free wet spinning—two-stage traction stretching—vacuum freeze-drying—semi-dry rapid carboxymethylation—needle punching / hydroentangling fabric formation": First, alcohol-free wet spinning avoids the use of organic solvents, making it environmentally friendly; second, two-stage traction stretching in a specific coagulation bath achieves a total fiber draw of 2.0 times, giving the fibers excellent mechanical strength and uniform diameter; third, vacuum freeze-drying preserves the porous structure inside the fibers, enhancing the breathability of the nonwoven fabric. The invention emphasizes the properties of chitosan and its adsorption capacity. Crucially, it employs a semi-dry, rapid carboxymethylation modification process to modify chitosan, significantly reducing solvent usage and side reactions. This achieves uniform and efficient carboxymethyl grafting, endowing the product with excellent hydrophilicity and antibacterial activity. Finally, the needle-punching and hydroentangling composite reinforcement eliminates the need for chemical adhesives, ensuring the material's biocompatibility. The resulting high-efficiency emergency antibacterial dressing possesses outstanding effects such as high moisture absorption and breathability, excellent mechanical strength, broad-spectrum antibacterial properties, and biodegradability, demonstrating significant application potential in medical materials. Attached Figure Description

[0037] Figure 1 Tensile stress-strain curves of four samples (S-cloth, Z-cloth, W-cloth, and G-cloth) in dry (A) and wet (B) conditions at room temperature;

[0038] Figure 2 Tensile stress-strain curves of four samples (S-cloth, Z-cloth, W-cloth, and G-cloth) in dry (A) and wet (B) states under humid heat aging conditions;

[0039] Figure 3 The bursting properties of four types of samples—S-cloth, Z-cloth, W-cloth, and G-cloth—were tested in both dry and wet states.

[0040] Figure 4 The tear strength properties of four types of samples—S-cloth, Z-cloth, W-cloth, and G-cloth—are presented in both dry and wet states.

[0041] Figure 5 The antibacterial rates of four types of samples: S-cloth, Z-cloth, W-cloth, and G-cloth.

[0042] Figure 6 WVTR and APR for four types of samples: S-cloth, Z-cloth, W-cloth, and G-cloth;

[0043] Figure 7The liquid absorption capacity of four types of samples: S-cloth, Z-cloth, W-cloth, and G-cloth.

[0044] Figure 8 The sensory evaluation results are for four types of samples: S-cloth, Z-cloth, W-cloth, and G-cloth. Detailed Implementation

[0045] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments. Obviously, the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in the art.

[0047] This invention provides a method for preparing a highly efficient emergency antibacterial dressing, comprising the following steps:

[0048] Step S1: Prepare chitosan spinning solution using acetic acid aqueous solution as solvent;

[0049] Step S2: The chitosan spinning solution is extruded into the first coagulation bath for primary drawing; then placed in the second coagulation bath for secondary drawing to obtain nascent fibers; wherein, the first coagulation bath is a mixed solution of sodium hydroxide and sodium sulfate, and the second coagulation bath is a sodium sulfate solution;

[0050] Step S3: Wash the nascent fibers until neutral, and freeze-dry them under vacuum to obtain chitosan fiber bundles;

[0051] Step S4: Immerse the chitosan fiber bundles in a first sodium hydroxide solution for treatment, centrifuge and dry to obtain alkalized fibers; mix the alkalized fibers with sodium chloroacetate at a dry weight ratio of 1:(1.2-1.5), add isopropanol (isopropanol:sodium chloroacetate mass ratio of (1.5-3):1) to form a paste, and obtain a paste; add a second sodium hydroxide solution to the paste and mix quickly and evenly to obtain a semi-dry etherified product; thoroughly knead and mix the semi-dry etherified product, and then react at 65-85 ℃ for 4-6 h; after washing and drying, obtain carboxymethyl chitosan fiber bundles;

[0052] Step S5: The carboxymethyl chitosan fiber bundles are woven into fabric to obtain a highly efficient emergency antibacterial dressing.

[0053] In some embodiments, the chitosan spinning solution is prepared as follows: chitosan is dissolved in an aqueous acetic acid solution with a mass fraction of 0.5%-5%, stirred at 15-35 °C for 2-6 h until completely dissolved, and then degassed under vacuum (0.05-0.8 MPa) for 5-120 min to obtain a chitosan spinning solution with a mass fraction of 3%-6%. During the preparation of the chitosan spinning solution, acetic acid provides H₂O. + It can protonate the amino groups of chitosan, break the hydrogen bonds between molecules, and promote dissolution; degassing treatment can prevent filament breakage caused by air bubbles during spinning.

[0054] In some embodiments, the chitosan spinning solution is extruded through a spinneret with an aperture of 0.05-1.0 mm.

[0055] In some embodiments, the first coagulation bath contains 1.5%-3.5% sodium hydroxide and 3%-4% sodium sulfate by mass; the first-stage draw ratio is 1-1.3 times. The second coagulation bath contains 8%-15% sodium sulfate by mass; the second-stage draw ratio is 1.3-1.7 times.

[0056] In some embodiments, the fineness of the nascent fibers is 0.8-1.5 dtex.

[0057] In some embodiments, the nascent fibers are washed to neutral as follows: the fiber bundle is dynamically countercurrently washed with deionized water at 30-60 °C 3-5 times, each time for 5-10 minutes, until neutral.

[0058] In some embodiments, the vacuum freeze-drying process is as follows: the fiber bundle is pre-frozen at -30 to -10 °C for 1-3 h, with the vacuum controlled at 100-150 Pa; then, the temperature is gradually increased to 30-50 °C over 1-3 h, and then further increased to 60-80 °C over 0.5-2 h, while maintaining a vacuum of 50-300 Pa, until the fiber temperature reaches 10-25 °C and the pressure inside the chamber stabilizes at 10-50 Pa. This invention, through vacuum freezing combined with gradient temperature drying, allows ice crystals to sublimate, leaving continuous channels and forming a porous framework, which facilitates the diffusion of reagent molecules and the exposure of binding sites. The inventors discovered in their research that if a conventional heating procedure is used after pre-freezing, the fiber structure will be damaged, leading to a decrease in the overall performance of the high-efficiency emergency antibacterial dressing.

[0059] In some embodiments, the mass concentration of the first sodium hydroxide solution is 8%-12%; in the second sodium hydroxide solution, the mass ratio of sodium hydroxide to water is 1:2.

[0060] In some embodiments, the operation of weaving the carboxymethyl chitosan fiber bundles into fabric is as follows: the carboxymethyl chitosan fiber bundles are cut into short fibers of 3-6 cm, combed into a web, and prepared into carboxymethyl chitosan nonwoven fabric (G-cloth), needle-punched fabric (Z-cloth) and hydroentangling fabric (W-cloth) using a needle punching machine (forward punching + reverse punching) and a hydroentangling machine (high pressure micro water jet).

[0061] Example 1

[0062] A highly effective emergency antibacterial dressing is prepared using the following steps:

[0063] (1) Preparation of spinning solution:

[0064] Chitosan was dissolved in a 3% aqueous acetic acid solution and mechanically stirred at 20 °C for 4 h until completely dissolved. Then, it was degassed under vacuum at 0.1 MPa for 40 min to obtain a chitosan spinning solution with a mass fraction of 4%.

[0065] (2) Alcohol-free wet spinning and two-stage traction stretching:

[0066] The chitosan spinning solution is extruded through a spinneret with a 0.10 mm aperture into a first coagulation bath for primary drawing, with a primary drawing ratio of 1.3 times; subsequently, it is placed in a second coagulation bath for secondary drawing, with a secondary drawing ratio of 1.5 times, resulting in a total drawing of approximately 2.0 times, to obtain nascent fibers; wherein, the first coagulation bath is a mixed solution of sodium hydroxide and sodium sulfate, with a sodium hydroxide mass fraction of 1.5% and a sodium sulfate mass fraction of 3.5%; the second coagulation bath is a sodium sulfate solution with a sodium sulfate mass fraction of 10%; the fineness of the nascent fibers is controlled at 1.0-1.2 dtex.

[0067] (3) Washing with water:

[0068] The fiber bundles were dynamically countercurrently washed three times with 40 ℃ deionized water for 5 minutes each time until neutral.

[0069] (4) Vacuum freezing + gradient temperature drying: Pre-freeze the fiber bundle at -20 ℃ for 1 h and control the vacuum to 100 Pa; then gradually increase the temperature to 40 ℃ within 2 h, and then increase the temperature from 40 ℃ to 70 ℃ within 1 h, while maintaining the vacuum at 50~300 Pa, until the fiber temperature reaches 15 ℃ and the pressure inside the chamber stabilizes at 20 Pa.

[0070] (5) Rapid carboxymethylation modification:

[0071] a. Immerse the fiber bundle in a 10% NaOH aqueous solution (room temperature) for 30 min, then centrifuge (3000 rpm, 10 min) to obtain alkalized fiber;

[0072] b. Mix alkalized fiber and sodium chloroacetate at a dry weight ratio of 1:1.2, and add isopropanol (the mass ratio of isopropanol to sodium chloroacetate is 2:1) to make a paste.

[0073] c. Take the second NaOH aqueous solution (the mass ratio of NaOH to water is 1:2) and add it to the paste (the dry weight mass ratio of the paste to NaOH is 1:0.8). Mix quickly and evenly to obtain a semi-dry etherified product.

[0074] d. Thoroughly knead and mix the semi-dry etherified compound, then place it in a constant temperature oven and react at 65 °C for 4 h;

[0075] e. Wash three times with 70% methanol aqueous solution, then rinse three to five times with deionized water until neutral;

[0076] f. Dry in a vacuum drying oven at 40℃ for 2 h to obtain carboxymethyl chitosan fiber bundles.

[0077] (6) Textile making:

[0078] Carboxymethyl chitosan fiber bundles were cut into short fibers of 3-6 cm, combed into a web, and then processed into carboxymethyl chitosan nonwoven fabrics (G-cloth), needle-punched fabrics (Z-cloth), and hydroentangling fabrics (W-cloth) using a needle punching machine (forward and reverse punching) and a hydroentangling machine (high-pressure micro water jet).

[0079] The performance of the carboxymethyl chitosan nonwoven fabric (G-cloth), needle-punched fabric (Z-cloth), and spunlace fabric (W-cloth) prepared in Example 1 was tested, and a commercial nonwoven fabric (S-cloth) was used as a control group to demonstrate the effectiveness of the method of the present invention compared with the conventional method.

[0080] 1. Tensile properties

[0081] Test method: As a medical wound dressing, it should have a certain mechanical strength to meet the function of support and protection and the toughness required for bandaging. Therefore, the mechanical properties of the three samples prepared in Example 1 were tested. According to the previous research method [1], with slight modifications, the samples were cut into strips with a length of 8 cm and a width of 2 cm. The strain height was set to 1 cm and the tensile speed was 10 mm / min for tensile fracture test. The tensile stress (MPa) and strain (%) were recorded. Each group of samples was tested at least 5 times and the average value was taken.

[0082] Figure 1The tensile stress-strain curves of dry (A) and wet (B) samples at room temperature are shown. The figure shows that the tensile stresses of the four samples in the dry state are 0.41 MPa (S-cloth), 5.10 MPa (Z-cloth), 1.91 MPa (W-cloth), and 0.62 MPa (G-cloth), with tensile strains of 41.39% (S-cloth), 24.23% (Z-cloth), 42.74% (W-cloth), and 29.75% (G-cloth), respectively. The tensile stresses of the four samples in the wet state are 0.19 MPa (S-cloth), 2.87 MPa (Z-cloth), 1.20 MPa (W-cloth), and 0.30 MPa (G-cloth), with tensile strains of 70.28% (S-cloth), 46.34% (Z-cloth), 45.25% (W-cloth), and 71.97% (G-cloth), respectively. Under both dry and wet conditions, Z-cloth and W-cloth significantly outperformed G-cloth. This may be attributed to the three-dimensional mechanical interlocking and ion-synergistic strengthening effect of Z-cloth, which improved the bonding force between fibers. The strong mechanical entanglement limited excessive fiber slippage and maintained the structural rigidity of the material. W-cloth's planar flexible entanglement and ion toughening effect maintained high flexibility, a loose structure, and good toughness. Furthermore, under wet conditions, the three samples prepared in Example 1 still maintained tensile stress values ​​of 37%-52%, with tensile strains increasing by 0.06, 0.91, and 1.42 times, respectively. This may be attributed to the fact that under wet conditions, some water molecules penetrated into the internal network of the material, disrupting some interchain hydrogen bonds and producing a plasticizing effect; in addition, Ca... 2+ Ionic crosslinking bridges formed with carboxyl groups on the polymer chain and Na + The synergistic effect of the generated ion-shielding electrostatic repulsion maintains a certain level of mechanical strength and structural integrity, reflecting the combined influence of polymer ion interactions, fiber network structure, and plasticization on controlling wet mechanical behavior.

[0083] 2. Tensile properties under damp heat aging

[0084] Test Method: The tensile properties of samples under accelerated aging conditions were determined using the constant damp heat method. Tensile property testing under damp heat aging conditions can accurately reflect the mechanical stability and structural durability of materials during long-term service in physiological temperature and humidity environments, providing crucial support for their reliability in practical applications as wound dressings. Previous methods... [1]Based on the previous method, slight modifications were made. The samples were cut into strips 8 cm long and 2 cm wide, and then placed in a constant temperature and humidity chamber (70 ℃, 80%RH) for accelerated aging for 7 days. After being removed, they were placed in a standard environment (25 ℃, 50%RH) for 24 h to equilibrate. Then, their tensile properties were measured. The strain height was set to 1 cm and the tensile speed was 10 mm / min. The tensile stress (MPa) and strain (%) were recorded. Each group of samples was tested at least 5 times, and the average value was taken.

[0085] Figure 2 The tensile stress-strain curves of dry (A) and wet (B) samples under hygrothermal aging conditions are shown. The figure shows that the tensile stresses of the four samples in the dry state are 0.32 MPa (S-cloth), 4.07 MPa (Z-cloth), 1.56 MPa (W-cloth), and 0.55 MPa (G-cloth), with tensile strains of 39.69% (S-cloth), 17.06% (Z-cloth), 51.77% (W-cloth), and 37.91% (G-cloth), respectively. The tensile stresses of the four samples in the wet state are 0.16 MPa (S-cloth), 2.33 MPa (Z-cloth), 1.17 MPa (W-cloth), and 0.20 MPa (G-cloth), with tensile strains of 6.46% (S-cloth), 3.73% (Z-cloth), 6.37% (W-cloth), and 6.12% (G-cloth), respectively. The above results may be attributed to the synergistic effect of water plasticization, ionic crosslinking, and fiber network structure evolution. The dense three-dimensional mechanically interlocked structure of Z-cloth effectively resists molecular chain relaxation and structural damage caused by hygrothermal aging. However, irreversible molecular chain breakage, hydrogen bond reconstruction, and partial ionic crosslinking failure occur under wet conditions, leading to a relative decrease in stress and strain. The planar fiber entanglement of W-cloth is affected by Ca... 2+ The ionic crosslinking part is strengthened, but the network depolymerization under wet conditions is significantly weakened. The G-cloth fiber entanglement is weak, and the molecular chain network is affected by long-term hydration, resulting in the most significant reduction in overall mechanical properties.

[0086] 3. Bursting performance

[0087] Test method: The bursting performance of the samples was determined by the steel ball bursting method, according to the standard method of GB / T 24218.5-2016 and previous research methods. [2]To conduct the test, the sample was equilibrated in a predetermined environment (25 ℃, 65% RH) for 24 h. A steel ball with a specification of 38 mm was used to clamp the sample evenly in the holder. The bursting speed was set to 10 mm / min. The bursting force (N) and bursting displacement (mm) were recorded. Five valid data were collected for each sample, and the average value and standard deviation were taken.

[0088] Bursting performance directly reflects a material's ability to resist localized external force penetration in practical applications. For example... Figure 3 As shown, compared to the control group S-cloth (16.3 N in dry state and 10.2 N in wet state), the W-cloth prepared in Example 1 achieved the highest breaking strength in both states: 106.84 N in dry state and 62.45 N in wet state, followed by Z-cloth (39.01 N / 24.47 N) and G-cloth (19.39 N / 11.51 N). This performance difference stems from the synergistic effect of process-induced three-dimensional fiber network structure, intermolecular interactions, and structural evolution caused by hydration. In the dry state, W-cloth forms a highly interlocked fiber network with maximum mechanical entanglement and ionic cross-linking, effectively dispersing stress and exhibiting ultra-high breaking strength. In the wet state, despite molecular chain expansion and partial hydrogen bond dissociation, the dense network maintains structural integrity, retaining approximately 58.5% of the dry state strength, demonstrating excellent wet mechanical stability. In contrast, Z-cloth and G-cloth exhibit relatively low entanglement and weak intermolecular forces, resulting in a significant decrease in strength upon hydration. These results provide a reasonable design strategy for high-performance medical dressings with excellent puncture resistance in moist wound environments.

[0089] 4. Tear resistance

[0090] Test method: The tear resistance of the samples was determined using the trapezoidal method. This was based on the standard method and research method of GB / T 3917.3-2025. [3] With slight modifications, the sample was equilibrated for 24 h in a predetermined environment (25 ℃, 65% RH), and cut into an isosceles trapezoid with an upper base of 75 mm, a lower base of 150 mm, and a height of 100 mm. A 20 mm slit was cut in the center of the short side, and the sample was stretched at a uniform speed of 100 mm / min to allow the tear to extend stably along the slit. The maximum force value and force-displacement curve during the effective tearing process were recorded. Five effective data points were tested in both the longitudinal and transverse directions, and the average value and standard deviation were taken.

[0091] Tear resistance is used to evaluate a material's ability to resist localized stress concentration and crack propagation during practical applications. For example... Figure 4As shown, the three samples prepared in Example 1 exhibited excellent tear resistance in both dry and wet conditions. Compared to the control group S-cloth (1.21N / 0.68N), the dry tear strengths of the three samples in Example 1 reached 3.12 N (Z-cloth), 7.89 N (W-cloth), and 2.87 N (G-cloth), respectively; the wet tear strengths were 1.14 N (Z-cloth), 4.24 N (W-cloth), and 1.31 N (G-cloth), respectively, indicating their excellent tear resistance. Compared to the control group S-cloth, the tear strength of the samples prepared in Example 1 increased by 2.37-6.52 times (dry state) and 1.92-6.24 times (wet state). This excellent mechanical property stems from the synergistic enhancement of multi-scale structural effects: at the molecular level, a high degree of substitution and uniform distribution of carboxymethyl groups were achieved. Compared to conventional processes (low degree of substitution and uneven distribution), the hydrogen bond and ionic crosslinking network constructed in this invention is denser and more ordered, significantly enhancing the tear resistance. Intermolecular cohesion effectively resists the plasticizing damage of interchain bonds by water molecules; at the same time, the uniformly distributed ionic groups endow the fiber with a stable charge repulsion balance in the wet state, avoiding local excessive swelling, thus maintaining excellent molecular chain segment stiffness and toughness in the wet state; at the grid level, the needle punching / hydroentanglement process constructs a highly interwoven three-dimensional fiber network, which dissipates a large amount of tearing energy through fiber slippage, pull-out and breakage, and maintains mechanical interlocking in the wet state. The combination of covalent / ionic crosslinking and hydrogen bonding, along with the three-dimensional fiber entanglement, endows it with excellent dry / wet mechanical stability.

[0092] 5. Antibacterial properties

[0093] Test method: The antibacterial properties of the samples were determined using the plate colony counting method. Based on previous methods... [4] Slight modifications were made, the sample was cut into small pieces and sterilized under ultraviolet light for 12 h; suspensions of Escherichia coli, Staphylococcus aureus and Candida albicans were prepared respectively; 20 mL of bacterial suspension was taken into centrifuge tube, 0.7 g of sample fragments were added, and the centrifuge tube was incubated in a shaking incubator at 37 ℃ and 140 r / min for 8 h. Then 100 µL was taken onto a solid agar plate, spread evenly, and incubated in a 37 ℃ incubator for 24 h. The antibacterial rate (AR) was calculated by formula (1). The blank control group was without sample fragments.

[0094] AR(%)=(A0-A1) / A0×100%(1);

[0095] Where A0 is the total number of colonies in the blank control group and A1 is the total number of colonies in the experimental group.

[0096] like Figure 5As shown, the three samples prepared in Example 1 exhibited broad-spectrum and highly effective antibacterial properties against three typical pathogenic bacteria (Candida albicans, Escherichia coli, and Staphylococcus aureus). Compared with the control group (70.43%-75.42%), their antibacterial rates were consistently maintained at a high level of over 80%. Among them, W-cloth achieved an antibacterial rate of up to 92% against Escherichia coli, demonstrating the excellent versatility and structural advantages of the three samples in antibacterial applications. This superior antibacterial performance is attributed to the multi-scale synergistic effect of molecular structure design, interfacial interactions, and microstructure regulation: at the molecular level, firstly, through selective substitution and amino protection—precisely controlling the reaction conditions—carboxymethyl groups were preferentially and densely substituted at the C6 hydroxyl group of chitosan, and the positively charged amino group (-NH3) was... + The surface density of the fiber is maintained at several times higher than that of ordinary samples, providing ample active sites for electrostatic sterilization. Secondly, uniform substitution and conformational extension—a mild, segmented etherification process ensures the gradual and highly uniform introduction of carboxymethyl groups along the molecular chain, avoiding "cluster aggregation" or molecular chain curling caused by excessive local reactions, maximizing the exposure of amino active groups to the outside, and improving the collision efficiency with the bacterial membrane surface. Finally, wet-state structure locking—a high-density ionic cross-linked network effectively inhibits excessive swelling of the fiber in the body fluid environment, ensuring that the surface amino areal density remains high even after long-term contact with liquid, thus ensuring the durability of antibacterial activity. At the structural level, the hydroentangling / needle-punching process constructs a highly cross-linked three-dimensional fiber network with a large specific surface area, increasing the contact efficiency with bacteria, physically capturing pathogens, and prolonging the antibacterial duration, thereby maximizing the antibacterial rate. Its porous structure ensures the permeable exchange of liquids (such as body fluids and environmental media) while inhibiting bacterial adhesion and proliferation through physical barrier action, thus constructing an antibacterial protection system from the dual dimensions of "chemical antibacterial" and "physical barrier".

[0097] 6. Water vapor transmission rate (WVTR) and liquid transmission rate (APR)

[0098] Test method: Based on the previous method [5-6] Slight modifications were made to determine the water vapor transmission rate (WVTR) and liquid transmission rate (APR) of the three samples. WVTR test: The sample was cut into a disc shape and placed on top of a cylindrical cup containing 2.5 mmol / L CaCl2·2H2O and 142 mmol / L NaCl. The cup was placed in an environment of 37 °C. The sample and the cylindrical cup were weighed periodically over 3 days. The water vapor transmission rate was calculated using formula (2). Five time measurements were performed on all samples, and the average value and its error were taken.

[0099] WVTR (g·m) -2 ·day -1)=(M1-M2) / (A×T)×24×106(2);

[0100] Where M1(g) and M2(g) are the masses of the permeable cup before and after the test, respectively, A is the effective area of ​​the permeable cylindrical cup with an inner radius of 25 mm, and T is the test time.

[0101] APR test: The sample is cut into a strip of length × width = 6 cm × 2 cm, vertically fixed on a support, and the lower end is immersed in deionized water or physiological saline. The immersion depth is constant and the liquid level is constant. Capillary action drives the liquid to rise spontaneously along the thickness of the sample. The height of the liquid rise is recorded at fixed time intervals, and the rise height-time relationship curve is plotted. The slope of the initial linear segment of the curve is taken as the capillary rise rate, and the unit is expressed in mm / s.

[0102] like Figure 6 As shown, the four samples exhibit distinct WVTR and APR characteristics, with the control sample S-cloth showing a WVTR and APR of 2279.14 g·m⁻¹. 2 ·day -1 With a velocity-to-weight ratio (WVTR) of 1569.36 mm / s, the W-cloth prepared in Example 1 outperformed Z-cloth, G-cloth, and the control sample S-cloth in both of these metrics. The WVTR of W-cloth was approximately 7000 g·m⁻¹. 2 ·day -1 Its APR peaks at approximately 2600 mm / s, reflecting its excellent water management capabilities. This performance is attributed to the synergistic effect of multi-scale structural design and molecular-level hydrophilic modulation: at the structural level, W-cloth constructs a three-dimensional fiber network with hierarchical porosity and excellent connectivity, acting as an efficient transport channel for water vapor and liquid; in contrast, the fiber networks formed by Z-cloth and G-cloth have relatively poor connectivity, resulting in lower mass transfer efficiency; at the molecular level, hydrophilic groups (-OH, -COO) are achieved. - The uniform and orderly grafting on the molecular chain constructs continuous and interconnected molecular-level hydrophilic channels, providing a low-energy-barrier adsorption-diffusion pathway for water molecules. In addition, the regular and orderly cross-linked network effectively inhibits excessive swelling of the fiber in a wet state, enhances surface wettability, and reduces the energy barrier for water molecule adsorption and diffusion. The combination of the hydrophilic molecular microenvironment and the hierarchical porous structure channels enables it to achieve rapid liquid absorption and efficient water vapor dissipation, which further demonstrates its great potential in high-humidity applications.

[0103] 7. Liquid absorption capacity

[0104] Test method: Based on the previous method[7] Slight modifications were made to determine the liquid absorption capacity of the samples. The samples were cut into squares of approximately 5 cm × 5 cm and dried in a vacuum oven at 40 ℃ for 4 h. The samples were then wrapped in nylon 66 fabric and immersed in a solution containing 2.5 mmol / L CaCl2·2H2O and 142 mmol / L NaCl at 37 ℃ for 8 h. The liquid absorption rate (R) was calculated using formula (3). All samples were tested five times, and the reported results are the average value and its error.

[0105] R(g·g) -1 )=(W2-W1) / W0×100%(3);

[0106] Wherein, W0 is the original weight of the sample, W1 is the weight of the sample with nylon 66 fabric, and W2 is the weight of the sample with nylon 66 fabric after 8 hours of soaking.

[0107] like Figure 7 As shown, all three samples prepared in Example 1 exhibited significant liquid absorption capacity, with G-cloth showing the highest absorption capacity at 31.07 g·g⁻¹. -1 The next best were Z-cloth and W-cloth, with absorbency of 18.54 g·g⁻¹, respectively. -1 and 10.76 g·g -1 The control group S-cloth had an absorbency of only 8.79 g·g. -1 This performance difference is attributed to the synergistic effect of molecular hydration and microstructure regulation: at the molecular level, ① a continuous array of hydrophilic groups constructs a complete hydration layer network, ensuring unobstructed diffusion paths for water molecules, whereas in conventional processes, water molecules frequently need to traverse hydrophobic water zones due to isolated hydrophilic sites, resulting in low transport efficiency; ② uniformly distributed -COO -The formation of a strong electrostatic repulsion force with consistent direction drives the coordinated swelling of molecular chains, exposing more internal hydrophilic sites and creating a positive feedback amplification of water absorption capacity. In contrast, conventional processes result in sluggish and uneven swelling response due to the mutual cancellation of repulsion forces. Furthermore, the high-density ionic cross-linking points and hydrogen bond network constitute a dynamically balanced "elastic" molecular framework, ensuring that the network swells without collapsing after water absorption, maintaining a stable nano-water storage space. In contrast, conventional processes result in sparse cross-linking, which easily loosens and collapses after water absorption, leading to a sharp drop in water storage capacity. At the network structure level, G-cloth constructs a highly fluffy three-dimensional fiber network with ample water storage space, maximizing the hydration effect and achieving a high water molecule absorption capacity. In comparison, W-cloth and Z-cloth, due to the dense entanglement of internal fibers, significantly compress the pore volume, limiting physical water storage capacity and resulting in lower absorption capacity. These data indicate that precisely controlling the liquid absorption performance of materials based on molding processes is a reasonable and effective approach.

[0108] 8. Sensory evaluation

[0109] Test method: Based on the previous method [8] The samples were then slightly modified to determine their sensory characteristics. Twenty members (10 males and 10 females) were recruited from different majors. The samples were subjectively and quantitatively scored based on eight indicators, including color uniformity, surface smoothness, odor, and gloss, using a 1-10 scoring system. Each group of samples was tested in parallel at least 10 times. After removing outliers, the average value was taken as the final sensory score to comprehensively evaluate the material's appearance quality and skin compatibility.

[0110] Sensory evaluation is used to systematically quantify the multi-dimensional user experience of materials, including color, touch, and surface smoothness, providing core evaluation criteria for their clinical suitability, wearing comfort, and user acceptance. For example... Figure 8 As shown, the four samples exhibited significant sensory performance characteristics across eight key evaluation indicators (color, uniformity, odor, surface condition, scratch resistance, smoothness, elasticity, and skin irritation) (specific scoring criteria are shown in Table 1). Compared to the control group S-cloth, the W-cloth prepared in Example 1 demonstrated superior color uniformity, surface smoothness, and elasticity, which is related to the synergistic effect of microstructural evolution, multi-scale mechanical response, and interfacial biocompatibility during the process. Z-cloth formed a moderately interwoven network structure, achieving a good balance between tactile comfort and mechanical strength. G-cloth's highly porous and fluffy surface structure provided excellent skin biocompatibility. Overall, all three samples prepared in the examples possessed high sensory properties.

[0111] Table 1: Sensory Evaluation Criteria

[0112]

[0113] In summary, the highly efficient emergency antibacterial dressing prepared by this invention through a systematic process of alcohol-free wet spinning, two-stage traction stretching, vacuum freeze-drying, semi-dry rapid carboxymethylation, and needle punching / hydroentanglement fabrication possesses both high mechanical strength and strong liquid absorption capacity. It can absorb a large amount of wound exudate and keep the wound moist, achieving a synergistic effect of multiple functions such as emergency response, anti-adhesion, strong stability, antibacterial properties, and wound healing promotion, and has good application prospects.

[0114] References:

[0115] [1] ZJ Jiang, LL Li, H. Li, LX Xia, HW Hu, S. Wang, CQ Liu,JH Chi, Y. Yang, FL Song, WS Liu, BQ Han, Preparation, biocompatibility, and wound healing effects of O-carboxymethyl chitosannonwoven fabrics in partial-thickness burn model, Carbohydrate Polymers, 280,15,119032, doi:10.1016 / j.carbpol.2021.119032.

[0116] [2] SNH Husain, AHA Rashid, MF Shaari, MNR, NNM Hassan, M RAAhmad, RA Rashid, Mechanical properties evaluation of nonwoven industrialcotton waste produced by needle punching method, IOP Conference SeriesMaterials Science and Engineering, 670 012035, doi:10.1088 / 1757-899X / 670 / 1 / 012035.

[0117] [3] J. H. Lin , Y.L. Hsing , W.H. Hsing , Y.J. Pan , C.T. Hsieh &C.W. Lou, Feasibility Assessments of the Use of Recycled Fibers in NonwovenFabrics, Applied Sciences, 7 (1), doi:10.3390 / app7010058.

[0118] [4] Y. J. Xu, L. M. Zou, H. W. Lu & T. J. Kang. Effect of differentsolvent systems on PHBV / PEO electrospun fibers, RSC Advances, 7 (2017), doi:10.1039 / c6ra26783a.

[0119] [5] J. C. Xu, C. Y. Zhang, T. S. Ge, Y. J. Dai & R. Z. Wang,Performance study of sodium alginate-nonwoven fabric composite membranes fordehumidification, Applied Thermal Engineering, 128, 214-224, doi: 10.1016 / j.applthermaleng.2017.09.020.

[0120] [6] Y.Y. Huang, H.M. Zhao, S.J. Chen, G. Wan & D.G. Miao, Preparationof multifunctional wound dressings with composite PVA / PE films, Journal ofMaterials Science, 57, 2115-2130, doi:10.1007 / s10853-021-06658-8.

[0121] [7] C. Li, Y. Huang, RH Li, Y. Wang, doi:10.1016 / j.carbpol.2020.117037.

[0122] [8] W. Song, J. Xu, LL Ren, L. Guo, J. Tong, LY Wang & ZYChang, Traditional Sensory Evaluation and Bionic Electronic Nose as Innovative Tools for the Packaging Performance Evaluation of Chitosan Film, 12 (10), doi:10.3390 / polym12102310.

[0123] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing a highly efficient emergency antibacterial dressing, characterized in that, Includes the following steps: A chitosan spinning solution was prepared using an aqueous acetic acid solution as a solvent. The chitosan spinning solution is extruded into a first coagulation bath for primary drawing; then placed in a second coagulation bath for secondary drawing to obtain nascent fibers; wherein, the first coagulation bath is a mixed solution of sodium hydroxide and sodium sulfate, and the second coagulation bath is a sodium sulfate solution; The nascent fibers were washed to neutral and then freeze-dried under vacuum to obtain chitosan fiber bundles. The chitosan fiber bundles were immersed in a first sodium hydroxide solution for treatment, centrifuged and dried to obtain alkalized fibers; the alkalized fibers were mixed with sodium chloroacetate at a dry weight ratio of 1:(1.2-1.5), and isopropanol was added to form a paste to obtain a paste; a second sodium hydroxide solution was added to the paste and quickly mixed evenly to obtain a semi-dry etherified product; the semi-dry etherified product was thoroughly kneaded and mixed, and then reacted at 65-85 ℃ for 4-6 h; after washing and drying, carboxymethyl chitosan fiber bundles were obtained. The carboxymethyl chitosan fiber bundles are woven into fabric to obtain a highly efficient emergency antibacterial dressing.

2. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 1, characterized in that, In the first coagulation bath, the mass fraction of sodium hydroxide is 1.5%-3.5%, and the mass fraction of sodium sulfate is 3%-4%.

3. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 2, characterized in that, In the second coagulation bath, the mass fraction of sodium sulfate is 8%-15%.

4. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 3, characterized in that, The first-stage draw ratio is 1-1.3 times, and the second-stage draw ratio is 1.3-1.7 times.

5. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 1, characterized in that, The vacuum freeze-drying process is as follows: the fiber bundle is pre-frozen at -30 to -10 ℃ for 1-3 h, and the vacuum is controlled to 100-150 Pa; then the temperature is gradually increased to 30-50 ℃ within 1-3 h, and then the temperature is increased from 30-50 ℃ to 60-80 ℃ within 0.5-2 h, while maintaining the vacuum at 50-300 Pa, until the fiber temperature reaches 10-25 ℃ and the pressure inside the chamber is stabilized at 10-50 Pa.

6. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 1, characterized in that, The preparation method of the chitosan spinning solution is as follows: dissolve chitosan in a 0.5%-5% acetic acid aqueous solution, stir at 15-35 ℃ for 2-6 h until completely dissolved, and then degas under vacuum for 5-120 min to obtain a chitosan spinning solution with a mass fraction of 3%-6%.

7. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 1, characterized in that, The chitosan spinning solution is extruded through a spinneret with an aperture of 0.05-1.0 mm.

8. The method for preparing a high-efficiency emergency antibacterial dressing according to claim 1, characterized in that, The fineness of the nascent fibers is 0.8-1.5 dtex.

9. A high-efficiency emergency antibacterial dressing prepared by the preparation method according to any one of claims 1-8.

10. The application of the high-efficiency emergency antibacterial dressing according to claim 9 in the preparation of medical materials.

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