An antibacterial hydrophilic fibrous dressing and a method of making the same

Abstract

The present application relates to the technical field of dressings, in particular to an antibacterial hydrophilic fiber dressing and a preparation method thereof. The preparation method comprises the following steps: firstly, TEMPO oxidized cellulose nanofiber, sodium alginate, polyethyleneimine and glycerol are dispersed and formed, and then freeze-drying is performed to obtain porous fibers containing carboxyl and amine sites; secondly, a first intrachain guanidination treatment is performed under acidic conditions to construct a guanidino network; thirdly, a surface adhesion layer is formed by dopamine self-polymerization in an alkaline Tris buffer, and 1-aminopropan-3-methyl imidazole chloride and 4-aminobenzoic acid are introduced to enhance hydrophilicity and dynamic moisture retention; fourthly, silver nitrate is immersed and reduced to load nanosilver in situ; fifthly, a second intrachain guanidination treatment is performed to strengthen antibacterial stability; and finally, drying and sterilization are performed. The obtained dressing has a high specific surface area, a low contact angle, excellent water vapor transmission rate and liquid absorption performance, and is particularly suitable for long-term nursing of high-exudation chronic wounds.

Description

Technical Field

[0001] This invention relates to the field of dressing technology, and in particular to an antibacterial hydrophilic fiber dressing and its preparation method. Background Technology

[0002] Chronic wounds, such as diabetic foot ulcers, place extremely high demands on dressing performance due to their high exudate levels, susceptibility to infection, and difficulty in healing. These wounds require dressings with highly efficient absorbency to manage excessive exudate while maintaining a moist environment to promote healing. However, currently used dressings often fall short in terms of absorbency and moisture retention. Silver-based antibacterial dressings, as a traditional choice, achieve their antibacterial effect by releasing silver ions. However, silver ions tend to migrate and burst-release rapidly in bodily fluids, leading not only to short-lived antibacterial effects but also the potential for cytotoxicity due to excessively high local concentrations, irritating wound tissue and delaying the healing process. Furthermore, the migration of silver ions often results in uneven distribution of antibacterial components within the dressing, making it difficult to provide sustained and effective protection to the wound.

[0003] While quaternary ammonium salt dressings possess cationic antibacterial properties, they also face similar problems: quaternary ammonium salt molecules readily dissolve from the dressing matrix, resulting in limited antibacterial durability, and their antibacterial effect rapidly diminishes under high exudate flushing. Furthermore, the charge properties of quaternary ammonium salts may interfere with the normal electrophysiological environment of the wound, increasing the risk of irritation. More importantly, existing silver halide or quaternary ammonium salt dressings primarily focus on antibacterial function, neglecting the synergistic design of absorbency and moisture maintenance. The absorbency of dressings depends on their pore structure and hydrophilicity, but traditional dressings have low porosity or insufficient hydrophilic groups, leading to slow absorption rates and limited absorbency, making it difficult to handle large amounts of exudate and easily causing wound maceration.

[0004] Furthermore, existing dressings perform poorly in terms of secondary absorption capacity, meaning they struggle to absorb newly generated exudate after the initial absorption, which is particularly pronounced in highly exudative wounds. Due to the lack of a dynamic moisturizing mechanism, dressings often dry rapidly or adhere to the wound surface after absorption, easily causing secondary damage during dressing changes. In addition, insufficient microbial barrier function allows bacteria to easily penetrate the dressing matrix, increasing the risk of infection. These problems collectively limit the application of existing dressings in chronic wounds, necessitating a novel dressing solution that balances long-lasting antibacterial action, rapid absorption, continuous moisturizing, and good breathability. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose an antibacterial hydrophilic fiber dressing and its preparation method, so as to solve the problems that existing antibacterial dressings have poor antibacterial durability due to the easy migration and rapid release of silver ions or quaternary ammonium salts, as well as slow absorption rate and weak moisture retention, which cannot meet the long-term treatment needs of high exudative chronic wounds such as diabetic foot.

[0006] To achieve the above objectives, the present invention provides a method for preparing an antibacterial hydrophilic fiber dressing, comprising the following steps:

[0007] (1) TEMPO oxidized cellulose nanofibers, sodium alginate, polyethyleneimine and glycerol were dispersed in deionized water, extruded into a calcium chloride coagulation bath, washed, pre-frozen and freeze-dried to obtain porous hydrophilic fibers containing carboxyl and amine sites.

[0008] (2) The porous hydrophilic fiber is subjected to a first intrachain guanidine treatment with dicyandiamide under acidic conditions to obtain porous fiber with the first intrachain guanidine treatment.

[0009] (3) Dopamine hydrochloride was self-polymerized on the porous fibers after the first intrachain guanidine treatment in alkaline Tris buffer to form a surface adhesion layer, and 1-aminopropyl-3-methylimidazolium chloride and 4-aminophenylboronic acid were introduced to obtain surface-modified porous fibers.

[0010] (4) The surface-modified porous fiber is immersed in silver nitrate aqueous solution and then transferred to ascorbic acid aqueous solution for in-situ reduction to obtain in-situ loaded silver nanofibers.

[0011] (5) The in-situ loaded silver nanofibers were subjected to a second intrachain guanidine treatment with dicyandiamide under acidic conditions to obtain a fiber dressing intermediate.

[0012] (6) Dry and sterilize to obtain antibacterial hydrophilic fiber dressing.

[0013] Preferably, the formulation in step (1) is as follows: 800-1200g of TEMPO oxidized cellulose nanofiber dispersion containing 1wt% solids, 200-300g of sodium alginate, 60-150g of polyethyleneimine aqueous solution containing 10wt% solids and 8-15g of glycerol are added to every 8000g of deionized water.

[0014] Preferably, in step (1), the carboxyl density of the TEMPO oxidized cellulose nanofibers is 1.4 mmol / g; and in step (1), the polyethyleneimine is branched and has a number-average molecular weight of 25,000.

[0015] Preferably, in step (1), the coagulation bath is a calcium chloride aqueous solution with a mass fraction of 1.5wt%-3wt% and a draw ratio of 1.5-3.

[0016] Preferably, in step (1), the washing is performed 2-4 times, the pre-freezing temperature is -20℃ and the time is 3-6 hours, and the freeze-drying time is 20-30 hours.

[0017] Preferably, in step (2), the dicyandiamide feeding is 35-55g per 100g of porous hydrophilic fiber.

[0018] Preferably, in step (2), the acidic condition is an aqueous hydrochloric acid solution with a concentration of 0.5 mol / L, a reaction temperature of 85-95℃, and a reaction time of 3-5 h.

[0019] Preferably, in step (3), the concentration of Tris buffer is 10 mmol / L and the pH is 8.5.

[0020] Preferably, in step (3), the amount of dopamine hydrochloride, 1-aminopropyl-3-methylimidazolium chloride and 4-aminophenylboronic acid added is 1.0-2.0 g per 100 g of porous fiber that has undergone the first intrachain guanidine treatment.

[0021] Preferably, in step (4), the silver nitrate aqueous solution is prepared by adding 0.03-0.08g of silver nitrate to 300g of deionized water.

[0022] Preferably, in step (4), the bath ratio of the surface-modified porous fiber in the silver nitrate aqueous solution is 1:3.

[0023] Preferably, in step (5), the dicyandiamide feed is 15-28g per 100g of in-situ loaded nano-silver fiber.

[0024] Preferably, in step (5), the acidic condition is an aqueous hydrochloric acid solution with a concentration of 0.2 mol / L, a reaction temperature of 55-65℃, and a reaction time of 0.5-1.5 h.

[0025] Preferably, step (6) involves drying the product under hot air conditions at 60°C until the moisture content is 5.0wt%-6.5wt%.

[0026] Furthermore, the present invention also provides an antibacterial hydrophilic fiber dressing, which is prepared by the above-described preparation method.

[0027] The beneficial effects of this invention are:

[0028] This invention achieves highly efficient liquid absorption and long-lasting antibacterial properties in dressings through the synergistic effect of a porous hydrophilic fiber framework and multiple modification processes. The porous structure, based on TEMPO oxidized cellulose nanofibers and sodium alginate, possesses a high specific surface area and interconnected pores, enabling rapid absorption and locking of large amounts of exudate. Simultaneously, the open channels formed through freeze-drying promote water vapor permeation, maintaining appropriate wound humidity. The introduction of polyethyleneimine further enhances the amino groups on the fibers, providing an active basis for subsequent modification.

[0029] Through two intrachain guanidineization processes, dicyandiamide reacts with carboxyl and amine groups in the fiber under acidic conditions to form a stable guanidine network. This network endows the dressing with a long-lasting positive charge, enabling it to adsorb and disrupt bacterial cell membranes through electrostatic interactions, achieving long-lasting antibacterial effects. The first guanidineization establishes a basic charge framework within the fiber, while the second guanidineization, after loading with silver nanoparticles, enhances the surface charge density, preventing premature loss of antibacterial components and thus improving antibacterial durability.

[0030] In the surface modification stage, dopamine hydrochloride undergoes a self-polymerization reaction in Tris buffer to form a polydopamine adhesion layer on the fiber surface, which exhibits excellent hydrophilicity and biocompatibility. The addition of 1-aminopropyl-3-methylimidazolium chloride introduces cationic imidazolium groups, enhancing the surface positive charge and hydration capacity, while 4-aminophenylboronic acid forms a dynamic moisturizing network through reversible coordination. The synergistic effect of these three components not only improves the dressing's instantaneous hydrophilicity but also achieves anti-adhesion and moisture maintenance, reducing tissue damage during dressing changes.

[0031] The time-series design of in-situ loaded silver nanoparticles optimizes the silver release behavior. Surface-modified fibers first adsorb silver ions, which are then reduced by ascorbic acid to generate silver nanoparticles. This process is confined within the fiber channels, preventing silver particle aggregation. The synergistic effect of the silver nanoparticles and the guanidine network prolongs the antibacterial time through a sustained-release mechanism, while reducing the risk of irritation from the sudden release of silver ions.

[0032] Overall, this invention achieves a balance in dressings regarding absorbency, moisture permeability, antibacterial efficiency, and barrier function through the integrated design and modification process. Porous hydrophilic fibers, acting as a carrier, combined with a surface modification layer and an internal guanidine network, collectively construct a multifunctional platform that can rapidly manage exudate while continuously inhibiting microbial growth, making it particularly suitable for long-term care of highly exudative chronic wounds. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0034] Figure 1 The infrared spectra of the porous hydrophilic fiber containing carboxyl and amine sites, the porous fiber with the first intrachain guanidine treatment, the surface-modified porous fiber, and the antibacterial hydrophilic fiber dressing in Example 2 of the present invention are shown.

[0035] Figure 2 This is a scanning electron microscope image of the antibacterial hydrophilic fiber dressing in Example 2 of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Example 1:

[0037] (1) Add 8000g of deionized water, 800g of TEMPO oxidized cellulose nanofiber aqueous dispersion (purchased from Novarials, catalog NovaWire-CNF-T, solid content 1wt%, carboxyl density 1.4mmol / g), 200g of sodium alginate powder (model PRONOVA® UP MVG), 60g of polyethyleneimine aqueous solution (purchased from ALADDIN, catalog P434400, branched type, number average molecular weight 25000, solid content 10wt%), and 8g of glycerol to a mixing tank, stir evenly and degas under vacuum for 30min, then extrude the spinning solution into a 30000g calcium chloride coagulation bath with a mass fraction of 1.5wt% and a draw ratio of 1.5, take out the fiber bundle and wash it twice with deionized water, pre-freeze at -20℃ for 3h, and then freeze-dry for 20h to obtain porous hydrophilic fibers containing carboxyl and amine sites;

[0038] (2) In an acid-resistant reactor, add 200g of deionized water, 35g of dicyandiamide, and 3.0mL of hydrochloric acid (concentration 0.5mol / L), heat to 85℃, add 100g of porous hydrophilic fiber containing carboxyl and amine sites, stir and keep warm for 3h, take out the fiber and wash it repeatedly with deionized water until neutral to obtain porous fiber with the first intrachain guanidine treatment;

[0039] (3) In a polypropylene tank, add 800g Tris buffer (concentration 10mmol / L, pH 8.5) and 1.0g dopamine hydrochloride, stir to dissolve, then add 1.0g 1-aminopropyl-3-methylimidazolium chloride, 1.0g 4-aminophenylboronic acid and 100g porous fibers that have undergone the first intrachain guanidine treatment, stir at room temperature for 1.5h, take out the fibers and wash them 3 times with deionized water to obtain surface-modified porous fibers;

[0040] (4) In a glass bath, add 300g of deionized water and 0.03g of silver nitrate, stir to dissolve, add 100g of surface-modified porous fiber, soak for 20min, take it out and soak it in 0.3mmol / L ascorbic acid aqueous solution, react at 35℃ for 20min, take out the fiber and wash it with deionized water 3 times to obtain in-situ loaded silver nanofibers.

[0041] (5) In an acid-resistant reactor, add 200g of deionized water, 15g of dicyandiamide and 10mL of hydrochloric acid (concentration 0.2mol / L), heat to 55℃ and add 100g of in-situ loaded nano-silver fiber, stir and react for 0.5h, wash with deionized water until neutral, and obtain fiber dressing intermediate with second intrachain guanidine treatment.

[0042] (6) The fiber dressing intermediates with the second intrachain guanidine treatment were dried with hot air at 60°C to a water content of 6.5wt%, cut into fiber dressings with a size of 10cm×10cm, sterilized by 25kGy gamma irradiation, and individually sealed in medical paper-plastic bags to obtain antibacterial hydrophilic fiber dressings. Example 2:

[0043] (1) Add 8000g of deionized water, 1000g of TEMPO oxidized cellulose nanofiber aqueous dispersion (purchased from Novarials, catalog NovaWire-CNF-T, solid content 1wt%, carboxyl density 1.4mmol / g), 250g of sodium alginate powder (model PRONOVA® UP MVG), 100g of polyethyleneimine aqueous solution (purchased from ALADDIN, catalog P434400, branched type, number average molecular weight 25000, solid content 10wt%), and 10g of glycerol to a mixing tank, stir evenly and degas under vacuum for 30min, then extrude the spinning solution into a 30000g calcium chloride coagulation bath with a mass fraction of 2wt%, with a draw ratio of 2, take out the fiber bundle and wash it 3 times with deionized water, pre-freeze at -20℃ for 4h, and then freeze-dry for 24h to obtain porous hydrophilic fibers containing carboxyl and amine sites;

[0044] (2) In an acid-resistant reactor, add 200g of deionized water, 42g of dicyandiamide, and 3.7mL of hydrochloric acid (concentration 0.5mol / L), heat to 90°C, add 100g of porous hydrophilic fiber containing carboxyl and amine sites, stir and keep warm for 4h, take out the fiber and wash it repeatedly with deionized water until neutral to obtain porous fiber with the first intrachain guanidine treatment;

[0045] (3) In a polypropylene tank, add 800g Tris buffer (concentration 10mmol / L, pH 8.5) and 1.6g dopamine hydrochloride, stir to dissolve, then add 1.6g 1-aminopropyl-3-methylimidazolium chloride, 1.6g 4-aminophenylboronic acid and 100g porous fibers that have undergone the first intrachain guanidine treatment, stir at room temperature for 2h, take out the fibers and wash them 3 times with deionized water to obtain surface-modified porous fibers;

[0046] (4) In a glass bath, add 300g of deionized water and 0.05g of silver nitrate, stir to dissolve, add 100g of surface-modified porous fiber, soak for 30min, take it out and soak it in 0.5mmol / L ascorbic acid aqueous solution, react at 40℃ for 30min, take out the fiber and wash it with deionized water 3 times to obtain in-situ loaded silver nanofibers.

[0047] (5) In an acid-resistant reactor, add 200g of deionized water, 21g of dicyandiamide, and 14.5mL of hydrochloric acid (concentration 0.2mol / L). After heating to 60°C, add 100g of in-situ loaded nano-silver fibers, stir and react for 1h, and wash with deionized water until neutral to obtain the fiber dressing intermediate with the second intrachain guanidine treatment.

[0048] (6) The fiber dressing intermediates with the second intrachain guanidine treatment were dried in hot air at 60°C to a water content of 5.8wt%, cut into fiber dressings with a size of 10cm×10cm, sterilized by 25kGy gamma irradiation, and individually sealed in medical paper-plastic bags to obtain antibacterial hydrophilic fiber dressings. Example 3:

[0049] (1) Add 8000g of deionized water, 1200g of TEMPO oxidized cellulose nanofiber aqueous dispersion (purchased from Novarials, catalog NovaWire-CNF-T, solid content 1wt%, carboxyl density 1.4mmol / g), 300g of sodium alginate powder (model PRONOVA® UP MVG), 150g of polyethyleneimine aqueous solution (purchased from ALADDIN, catalog P434400, branched type, number average molecular weight 25000, solid content 10wt%), and 15g of glycerol to a mixing tank, stir evenly and degas under vacuum for 30min, then extrude the spinning solution into a 40000g calcium chloride coagulation bath with a mass fraction of 3wt%, the draw ratio is 3, take out the fiber bundle and wash it 4 times with deionized water, pre-freeze at -20℃ for 6h, and then freeze-dry for 30h to obtain porous hydrophilic fibers containing carboxyl and amine sites;

[0050] (2) In an acid-resistant reactor, add 200g of deionized water, 55g of dicyandiamide, and 5.5mL of hydrochloric acid (concentration 0.5mol / L), heat to 95℃, add 100g of porous hydrophilic fiber containing carboxyl and amine sites, stir and keep warm for 5h, take out the fiber and wash it repeatedly with deionized water until neutral to obtain porous fiber with the first intrachain guanidine treatment;

[0051] (3) In a polypropylene tank, add 800g Tris buffer (concentration 10mmol / L, pH 8.5) and 2.0g dopamine hydrochloride, stir to dissolve, then add 2.0g 1-aminopropyl-3-methylimidazolium chloride, 2.0g 4-aminophenylboronic acid and 100g porous fibers that have undergone the first intrachain guanidine treatment, stir at room temperature for 3h, take out the fibers and wash them 3 times with deionized water to obtain surface-modified porous fibers;

[0052] (4) In a glass bath, add 300g of deionized water and 0.08g of silver nitrate, stir to dissolve, add 100g of surface-modified porous fiber, soak for 40min, take it out and soak it in 0.8mmol / L ascorbic acid aqueous solution, react at 45℃ for 40min, take out the fiber and wash it with deionized water 3 times to obtain in-situ loaded silver nanofibers.

[0053] (5) In an acid-resistant reactor, add 200g of deionized water, 28g of dicyandiamide and 20mL of hydrochloric acid (concentration 0.2mol / L), heat to 65℃ and add 100g of in-situ loaded nano-silver fiber, stir and react for 1.5h, wash with deionized water until neutral, and obtain fiber dressing intermediate with second intrachain guanidine treatment.

[0054] (6) The fiber dressing intermediates with the second intrachain guanidine treatment were dried with hot air at 60°C to a water content of 5.0 wt%, cut into fiber dressings with a size of 10 cm × 10 cm, sterilized by 25 kGy gamma irradiation, and individually sealed in medical paper-plastic bags to obtain antibacterial hydrophilic fiber dressings.

[0055] Comparative Example 1:

[0056] The difference between Comparative Example 1 and Example 2 is that the second intrachain guanidine treatment in step (5) is not performed, and step (6) is performed directly after step (4); the other conditions are the same as in Example 2.

[0057] Comparative Example 2:

[0058] The difference between Comparative Example 2 and Example 2 is that the surface modification of polydopamine, 1-aminopropyl-3-methylimidazolium chloride and 4-aminophenylboronic acid in step (3) is not performed, and the process proceeds directly to step (4) after step (2); the other conditions are the same as in Example 2.

[0059] Comparative Example 3:

[0060] The difference between Comparative Example 3 and Example 2 is that 1-aminopropyl-3-methylimidazolium chloride is not added in step (3); the other conditions are the same as in Example 2.

[0061] Comparative Example 4:

[0062] The difference between Comparative Example 4 and Example 2 is that 4-aminophenylboronic acid is not added in step (3); the other conditions are the same as in Example 2.

[0063] Comparative Example 5:

[0064] The difference between Comparative Example 5 and Example 2 is that the in-situ loading of nano-silver in step (4) is adjusted to be performed after step (5), that is, the order becomes "first intrachain guanidineization, surface modification, second intrachain guanidineization, in-situ loading of nano-silver, drying and sterilization"; the other conditions are the same as in Example 2.

[0065] Comparative Example 6:

[0066] The difference between Comparative Example 6 and Example 2 is that the mass of dicyandiamide in step (2) was adjusted from 42g to 21g, while the volume of hydrochloric acid, reaction temperature and time remained unchanged; the other conditions were the same as in Example 2.

[0067] Performance testing:

[0068] Infrared spectroscopy: scanning range 4000-400cm -1 4cm resolution -1 The result is as follows Figure 1 As shown.

[0069] Scanning electron microscope: 100x magnification, results as follows Figure 2 As shown.

[0070] Specific surface area: 100 mg of sample was degassed under vacuum at 120℃ for 6 h and then subjected to nitrogen adsorption at liquid nitrogen temperature. The specific surface area was determined by the BET method. The results are shown in Table 1.

[0071] Surface hydrophilicity: Referring to GB / T 30693-2014, the sample was pressed into a flat surface under 10MPa, and 5μL of deionized water was added. After 5s, the static contact angle was measured by taking a picture. The average of the left and right sides was taken as one result, n=5. The contact angle was reported, and the results are shown in Table 1.

[0072] Water vapor transmission rate: The water vapor transmission rate was tested according to YY / T 0471.2-2004 at 21℃ and 60%RH, using the standard cup method. The mass change over 24 hours was recorded and converted to WVTR (g·m³). -2 24h -1 The results are shown in Table 1.

[0073] Liquid absorbency: Prepare a standard electrolyte solution according to YY / T 0471.1-2004, freely absorb the liquid at 37℃ and record the amount of liquid absorbed per unit area (g / 100cm²). 2 ), aspiration rate (g / 10min) and secondary aspiration (g / 100cm) 2 Sample size 10cm × 10cm, n = 3; report the test temperature, time, absorbance volume, and calculation formula. This method evaluates the dressing's ability to treat exudate.

[0074] Antibacterial properties: Escherichia coli, Staphylococcus aureus and Candida albicans standard strains were selected according to GB / T 20944.3-2008 to prepare inoculum. The samples were placed in Erlenmeyer flasks and shaken at 37℃ for 18 hours. The viable bacteria count was then measured and the inhibition rate was calculated. The results are shown in Table 1.

[0075] Bacterial barrier: The antibacterial performance was evaluated according to YY / T 0471.5-2017, and the barrier efficiency (%) was recorded. The challenge bacteria was Staphylococcus aureus aerosol, and the differential pressure and exposure time were set according to the standard.

[0076] Table 1 Performance Test Results

[0077]

[0078] Data Analysis:

[0079] As can be seen from the data in Examples 1-3 in Table 1, the fiber dressing prepared by this invention achieves a synergistic improvement in liquid absorption capacity, moisture permeability, and microbial barrier function under the dual regulation of the hydrophilic interface and porous framework, while maintaining high-efficiency inhibition against common pathogens and fungi. The underlying mechanism lies in the fact that intrachain guanidine provides a stable positive charge network, which works together with the strong hydration layer formed by the surface ternary components. This facilitates the rapid absorption and reabsorption of exudate in the pores, while also reducing the initial burst release of silver and enhancing its destructive effect on the bacterial biofilm.

[0080] As can be seen from the data in Example 2 and Comparative Example 1 in Table 1, without secondary intrachain guanidineization, the coating's sustained hydrophilicity and barrier properties decreased, and the antibacterial rate was also slightly lower. The main reason is that secondary guanidineization resulted in insufficient compensation and fixation of the surface positive charge after the formation of silver nanoparticles, leading to weakened stability of the interfacial hydration layer and silver release closer to the initial burst release. Therefore, two-stage guanidineization can significantly improve the coupling effect of durable antibacterial properties and barrier performance without sacrificing liquid absorption and moisture permeability.

[0081] As can be seen from the data in Example 2 and Comparative Example 2 in Table 1, after removing the synergistic interface of dopamine, 1-aminopropyl-3-methylimidazolium chloride, and 4-aminophenylboronic acid, the hydrophilicity and WVTR significantly decreased, and the liquid absorption-related indicators were also limited. The main reason is the lack of catechol-amine-dominated adhesion and hydration, resulting in the loss of confinement for silver nucleation, leading to larger and unevenly distributed particles, and partial blockage of pores. Therefore, it is evident that the ternary surface layer exhibits synergy in hydrophilicity, confinement, and silver stabilization, which is far more than a simple additive process.

[0082] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, the removal of 1-aminopropyl-3-methylimidazolium chloride weakened surface charge and wetting, resulting in a lower contact angle and WVTR compared to Example 2, and a decrease in antibacterial rate. The main reason for this is the reduced charge density and surface activity provided by 1-aminopropyl-3-methylimidazolium chloride, leading to poorer nucleation and dispersibility of silver nanoparticles and a thinner interfacial hydration layer. These results suggest that 1-aminopropyl-3-methylimidazolium chloride, dopamine, and 4-aminophenylboronic acid have a synergistic amplification effect in interfacial regulation.

[0083] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, the removal of the 4-aminophenylboronic acid component resulted in a decrease in hydrophilicity retention and secondary liquid absorption. The main reason is that the reversible coordination of the borate group of 4-aminophenylboronic acid with the polyol facilitates the formation of a dynamic hydration network and interacts with catechols to stabilize the surface layer; its absence worsens interfacial water retention and wetting recovery capabilities. This demonstrates that 4-aminophenylboronic acid synergizes with other components in dynamic moisturizing, anti-adhesion, and confined nucleation.

[0084] As can be seen from the data of Example 2 and Comparative Example 5 in Table 1, shifting the silver loading order to the later stage will cause an abnormal decrease in the WVTR and Candida albicans inhibition rate. The main reason is the lack of interfacial fixation and secondary guanidine reinforcement before silver formation. Silver is prone to agglomeration and is released too quickly in the early stage, which reduces the continuous inhibition of fungi and weakens the moisture permeability due to the pore-blocking effect.

[0085] As can be seen from the data in Example 2 and Comparative Example 6 in Table 1, while reducing the initial guanidineization intensity leads to an increase in the liquid absorption rate and volume, it also reduces the antimicrobial rate and barrier performance. The main reason is that the reduction in positively charged sites makes the network looser, resulting in faster short-term liquid absorption; however, the density of active sites and the interfacial stability of silver are insufficient, leading to a weakened ability to control microorganisms. This indicates that moderate intrachain guanidineization is the key balance point for achieving both liquid absorption and antimicrobial activity.

[0086] from Figure 1 It can be seen that with the evolution of porous fibers containing carboxyl / amine groups, first guanidineization, surface modification, and final dressing, the 3200-3500cm... -1 Broadband is gradually being enhanced and widened, to 1650±10cm -1 With approximately 1540cm -1 The guanidinium-related band was significantly increased, while the 1600 / 1410 cm band was significantly larger. -1 The absorption of a pair of carboxyl groups initially decreased and then stabilized; after surface modification, 1335 / 1190 cm⁻¹ appeared. -1 (BO) and 1510cm -1 Characteristic peaks such as (aromatic ring C=C) were observed; the final sample retained these surface marker peaks and the guanidine band was further enhanced.

[0087] from Figure 2It can be seen that the antibacterial hydrophilic fiber dressing is formed by continuous fibers with a diameter of about 5-10 μm interwoven to form a three-dimensional interconnected network. A large number of bright particles are uniformly anchored on the fiber surface with little obvious aggregation. The channels between fibers remain interconnected, proving that the nano-silver grows in a confined space and is firmly fixed by the guanidine network and the polydopamine adhesion layer.

[0088] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

Claims

1. A method for preparing an antibacterial hydrophilic fibrous dressing, characterized by, It comprises the following steps: (1) TEMPO-oxidized cellulose nanofiber, sodium alginate, polyethyleneimine and glycerol are dispersed in deionized water, extruded into a calcium chloride coagulation bath to form, washed, pre-frozen and freeze-dried to obtain a porous hydrophilic fiber containing carboxyl and amine sites; (2) The porous hydrophilic fiber is treated with dicyandiamide for the first intrachain guanidination under acidic conditions to obtain a first intrachain guanidination treated porous fiber; (3) The dopamine hydrochloride is self-polymerized on the first intrachain guanidination treated porous fiber in a Tris buffer solution to construct a surface adhesion layer, and 1-aminopropyl-3-methyl imidazole chloride and 4-aminobenzoic acid are introduced to obtain a surface modified porous fiber; (4) The surface modified porous fiber is immersed in an aqueous silver nitrate solution and then transferred to an aqueous ascorbic acid solution for in-situ reduction to obtain a fiber loaded with nano-silver in-situ; (5) The fiber loaded with nano-silver in-situ is treated with dicyandiamide for the second intrachain guanidination under acidic conditions to obtain a fiber dressing intermediate; (6) Drying and sterilization to obtain an antibacterial hydrophilic fiber dressing; The formula in step (1) is: 800-1200 g of TEMPO-oxidized cellulose nanofiber dispersion with a solid content of 1 wt% is added to 8000 g of deionized water, 200-300 g of sodium alginate, 60-150 g of polyethyleneimine aqueous solution with a solid content of 10 wt%, and 8-15 g of glycerol; The dicyandiamide dosage in step (2) is 35-55 g per 100 g of porous hydrophilic fiber; The addition amount of dopamine hydrochloride, 1-aminopropyl-3-methyl imidazole chloride and 4-aminobenzoic acid in step (3) is 1.0-2.0 g per 100 g of first intrachain guanidination treated porous fiber; The dicyandiamide dosage in step (5) is 15-28 g per 100 g of fiber loaded with nano-silver in-situ.

2. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The carboxyl density of TEMPO-oxidized cellulose nanofiber in step (1) is 1.4 mmol / g; The polyethyleneimine in step (1) is branched with a number average molecular weight of 25000.

3. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The coagulation bath in step (1) is a calcium chloride aqueous solution with a mass fraction of 1.5 wt%-3 wt%, and the draw ratio is 1.5-3.

4. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The washing in step (1) is 2-4 times, the pre-freezing temperature is-20℃, the time is 3-6 h, and the freeze-drying time is 20-30 h.

5. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The acidic condition in step (2) is an aqueous hydrochloric acid solution with a concentration of 0.5 mol / L, the reaction temperature is 85-95℃, and the time is 3-5 h.

6. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The Tris buffer solution concentration in step (3) is 10 mmol / L, and the pH is 8.

5.

7. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The silver nitrate aqueous solution in step (4) is prepared by adding 0.03-0.08 g of silver nitrate to 300 g of deionized water.

8. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The bath ratio of the surface modified porous fiber in the silver nitrate aqueous solution in step (4) is 1:

3.

9. The method of making an antimicrobial hydrophilic fibrous dressing according to claim 1, wherein, The acidic condition in step (5) is an aqueous hydrochloric acid solution with a concentration of 0.2 mol / L, the reaction temperature is 55-65℃, and the time is 0.5-1.5 h.

10. An antimicrobial hydrophilic fibrous dressing, characterized by, The antibacterial hydrophilic fiber dressing is prepared by the method of any one of claims 1-9. The antibacterial hydrophilic fiber dressing is prepared by the method of any one of claims 1-9.

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