Alginate chitosan composite hemostatic non-woven fabric and preparation method thereof

Abstract

The invention relates to the technical field of medical materials, and discloses an alginate and chitosan composite hemostatic non-woven fabric and a preparation method thereof.The preparation method comprises the steps that chitosan is converted into water-soluble carbamic acid esterified chitosan in a carbon dioxide environment with the pressure of 2.0-4.0 MPa, and the water-soluble carbamic acid esterified chitosan is mixed with alginate and an ion selective chelating agent to prepare a homogeneous spinning precursor solution; then, squeezing the precursor solution into an acidic coagulating bath with the pH value of 5.0-6.0 and containing Ca < 2 + > and Zn < 2 + > through wet spinning; in a coagulating bath, the carbamic acid esterified chitosan is decomposed and recovered into chitosan, the chitosan and the alginate form a polyelectrolyte compound, meanwhile, the alginate is cross-linked by Ca < 2 + > to form a fiber skeleton, through a reversible chemical modification method, the technical problem of direct mixing of the alginate and the chitosan is solved, the composite fiber with a uniform structure is obtained, and the preparation method is simple and easy to implement. And a stable zinc ion storage system is constructed in the fiber, so that the preparation process is simplified.

Description

Technical Field

[0001] This invention relates to the field of medical materials technology, specifically to an alginate-chitosan composite hemostatic nonwoven fabric and its preparation method. Background Technology

[0002] In the fields of trauma management and surgery, the application of medical hemostatic materials is crucial for controlling bleeding, preventing infection, and promoting wound healing. Alginate dressings, especially calcium alginate fiber dressings, are currently a widely used type of product in clinical practice. Their mechanism of action lies in the fact that when the dressing comes into contact with blood or exudate from the wound, calcium ions (CaO) in the fibers release oxygen. 2+ ) and sodium ions (Na) in the liquid + An exchange occurs, causing the fibers to swell and transform into a moist gel, which provides a moist healing environment for the wound. Simultaneously, the released calcium ions can act as coagulation factor IV, participating in and activating the intrinsic coagulation pathway.

[0003] Chitosan is another naturally derived cationic polysaccharide. Its hemostatic mechanism differs from alginate; it primarily relies on the positive charge of the protonated amino groups on its molecular chain. This allows it to directly adsorb and aggregate negatively charged red blood cells and platelets in the blood, forming a physical thrombus and achieving rapid hemostasis. Furthermore, chitosan itself possesses broad-spectrum antibacterial activity. Therefore, combining alginate and chitosan to obtain composite hemostatic materials that combine the functional properties of both is a promising technological development direction in this field.

[0004] However, there is an inherent technical challenge in preparing homogeneous composite fibers from these two materials. Alginate is an anionic polymer, while chitosan is a cationic polymer in the aqueous solution (typically weakly acidic) used for preparation. When the two are directly mixed in the aqueous phase, the electrostatic attraction between the positive and negative charges causes them to immediately form a water-insoluble polyelectrolyte complex precipitate. This precipitation makes it impossible to prepare a macroscopically and microscopically homogeneous spinning precursor solution for wet spinning, thus hindering the production of composite fibers with a homogeneous internal structure.

[0005] Furthermore, to further endow hemostatic materials with the function of promoting tissue repair, existing technologies often attempt to introduce functional metal ions, such as zinc ions (Zn). 2+ Zinc ions have been shown to participate in various enzymatic reactions and regulate cell proliferation and differentiation. Currently, the conventional method for introducing zinc ions into fibrous materials is post-treatment soaking, where the fibers are immersed in a zinc-containing solution after forming. This method results in weak binding forces, primarily through physical adsorption. Consequently, in practical applications, zinc ions are rapidly released initially, making it difficult to achieve a continuous and stable supply during the wound healing process, thus limiting the effective exertion of its functional effects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an alginate-chitosan composite hemostatic nonwoven fabric and its preparation method, which solves the problems of alginate and chitosan being unable to form a homogeneous spinning precursor solution due to electrostatic interaction, leading to difficulties in the preparation of composite fibers, and the difficulty in achieving controlled and sustained release of functional ions in existing materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an alginate-chitosan composite hemostatic nonwoven fabric and its preparation method, comprising: The first aspect of this invention provides an alginate-chitosan composite hemostatic nonwoven fabric, wherein the nonwoven fabric is composed of composite fibers, the composite fibers being made of the following components in parts by weight: alginate: 60-85 parts; chitosan: 15-40 parts; p-Zn 2+ With comparison Ca 2+ Ion-selective chelating agents with higher selective affinity: 0.1-2.0 parts.

[0008] In the composite fiber, the carboxyl groups of the alginate and the protonated amino groups of the chitosan form a polyelectrolyte complex through electrostatic interaction; the ion-selective chelating agent chelates Zn. 2+ And it is uniformly distributed at the molecular level in the matrix of the composite fiber.

[0009] In one specific embodiment, the ion-selective chelating agent is ethylenediamine-N,N′-disuccinic acid.

[0010] A second aspect of the present invention provides a method for preparing the aforementioned alginate-chitosan composite hemostatic nonwoven fabric, the method comprising the following steps: S1: Preparation of homogeneous spinning precursor solution: First, chitosan powder is mixed with Zn 2+ With comparison Ca 2+ A more selective ion-selective chelating agent with higher selective affinity is dispersed in an aqueous medium; then, a reaction is carried out in a carbon dioxide environment at a pressure of 2.0-4.0 MPa, so that the amino groups on the chitosan molecular chain react with carbon dioxide to generate water-soluble carbamate-treated chitosan; then, the solution containing carbamate-treated chitosan and the ion-selective chelating agent is mixed with an aqueous solution of alginate to obtain a homogeneous spinning precursor solution.

[0011] S2: Wet spinning: The homogeneous spinning precursor solution obtained in S1 is extruded through a spinneret and fed into a coagulation bath to form composite fibers; the coagulation bath is an acidic aqueous solution with a pH of 5.0-6.0, and also contains Ca. 2+ and Zn 2+ In the coagulation bath, the following process occurs: The carbamate-esterified chitosan decomposes under acidic conditions, reverting to chitosan; The carboxyl groups of the alginate react with the Ca in the coagulation bath. 2+ Ionic cross-linking occurs, forming a fiber backbone; The amino groups of the restored chitosan are protonated in an acidic environment and form an in-situ polyelectrolyte complex with the carboxyl groups of the alginate. Zn in coagulation bath 2+ It diffuses into the fiber interior and is captured by pre-distributed ion-selective chelating agents.

[0012] S3: Post-processing molding: The composite fibers formed in S2 are sequentially washed, stretched and dried to obtain continuous filaments; then the continuous filaments are cut into short fibers, and the short fibers are entangled with each other by hydroentangling process to prepare nonwoven fabric.

[0013] In one specific embodiment, in S1, when preparing the homogeneous spinning precursor solution, the initial mass concentrations of each component are: the mass concentration of alginate is 2.0%-5.0% w / v, the mass concentration of chitosan is 1.0%-3.0% w / v, and the mass concentration of the ion-selective chelating agent is 0.05%-0.2% w / v.

[0014] In one specific implementation, in S1, the reaction is carried out in a carbon dioxide environment under the following conditions: at a temperature of 20-25°C, the reaction is carried out for 1.5-2.5 hours.

[0015] In one specific embodiment, the coagulation bath in S2 consists of an aqueous solution of calcium acetate, zinc sulfate or zinc acetate, and acetic acid. The calcium acetate has a mass concentration of 2.0%-5.0% w / v, and the zinc sulfate or zinc acetate has a mass concentration of 0.1%-0.5% w / v.

[0016] In one specific implementation, in step S3, the stretching ratio is 1.2-1.8 times.

[0017] In one specific implementation, in S3, the hydroentangling pressure used in the hydroentangling process is 3.0-6.0 MPa.

[0018] In one specific embodiment, after step S3, the preparation method further includes a step of irradiating the prepared nonwoven fabric with radiation. The irradiation sterilization uses a cobalt-60 radiation source with an absorbed dose of 15-25 kGy.

[0019] This invention provides an alginate-chitosan composite hemostatic nonwoven fabric and its preparation method. It has the following beneficial effects: 1. This invention involves a reversible urethane esterification reaction of chitosan under carbon dioxide pressure, temporarily converting the amino groups on the chitosan molecular chain into carbamate groups, thereby altering the charge properties of chitosan. This technique enables chitosan to form a stable and homogeneous spinning precursor solution with negatively charged alginate in aqueous solution, fundamentally solving the problem of uneven mixing and precipitation caused by electrostatic attraction between the two polymers. This provides a technical basis for preparing composite fibers with homogeneous structure and stable performance.

[0020] 2. The preparation method employed in this invention integrates multiple physicochemical processes and completes them simultaneously in the coagulation bath step of wet spinning. Specifically, when the homogeneous spinning precursor solution enters the acidic coagulation bath, three key processes are triggered simultaneously: the decomposition of urethane-esterified chitosan, the calcium ion crosslinking of alginate, and the formation of a polyelectrolyte complex between the recovered chitosan and alginate. This "one-bath, multi-effect" in-situ reaction mechanism not only greatly simplifies the process flow but also ensures the formation of a dense interpenetrating network structure at the instant of fiber solidification, thereby endowing the final product with excellent structural integrity and wet strength.

[0021] 3. This invention achieves this by pre-uniformly dispersing Zn in the spinning precursor solution. 2+ Ion-selective chelating agents with high selective affinity, and in the presence of Zn 2+ Spinning was performed in a coagulation bath, enabling precise capture and uniform distribution of functional zinc ions within the fiber matrix. This pre-designed ion-loading method at the molecular level constructs a stable ion storage system. This system allows the final nonwoven fabric to release zinc ions sequentially in response to the external microenvironment, providing a structural basis for the material to achieve a functional transformation from initial antibacterial properties to later healing-promoting effects. Detailed Implementation

[0022] Example: Example 1 This embodiment provides a method for preparing an alginate-chitosan composite hemostatic nonwoven fabric.

[0023] (1) Preparation of homogeneous spinning precursor solution: First, weigh 2.0 g of chitosan powder and 0.125 g of ethylenediamine-N,N′-disuccinic acid powder, disperse them together in 80 mL of deionized water, and stir to form a uniform suspension. Adjust the pH value to 8.2 using 1.0 M sodium hydroxide aqueous solution. Transfer the solution to a high-pressure reactor, introduce high-purity carbon dioxide gas, and make the pressure inside the reactor reach and stabilize at 3.0 MPa. Stir and react at 22 °C for 2.0 hours to obtain a urethane-esterified chitosan / EDDS mixed mother liquor. Separately weigh 3.5 g of sodium alginate, dissolve it in 100 mL of deionized water, stir and degas under vacuum to obtain a sodium alginate solution. Under the condition of maintaining the pressure inside the reactor at 3.0 MPa, pump the sodium alginate solution into the reactor and mix it with the above mother liquor. Continue stirring for 45 minutes to obtain a homogeneous spinning precursor solution.

[0024] (2) Preparation of functionalized coagulation bath: Weigh 35.0g of calcium acetate and 3.0g of zinc sulfate and dissolve them in deionized water. Adjust the pH to 5.5 using glacial acetic acid, and finally bring the volume to 1L with deionized water.

[0025] (3) Wet spinning and fiber forming: The homogeneous spinning precursor solution prepared in step (1) is extruded through a spinneret with a pore size of 100 μm at a flow rate of 0.3 mL / min and enters the coagulation bath prepared in step (2). The nascent fibers are drawn out after traveling 80 cm in the coagulation bath, and then washed with water, and stretched by 1.5 times during the washing process. The stretched fiber bundles are dried in an oven at 70 °C to obtain continuous filaments.

[0026] (4) Preparation and final treatment of nonwoven fabric: The dried continuous filaments were cut into short fibers with a length of 45 mm. A certain amount of short fibers were taken, opened, and combed to form a fiber web with a basis weight of 45 g / m². The fiber web was reinforced using a hydroentangling machine with a hydroentangling pressure set to 4.5 MPa. The hydroentangled nonwoven fabric was dried, cut, and sealed in packaging. Finally, it was sterilized by radiation using a cobalt-60 radiation source with an absorbed dose of 20 kGy to obtain the final product.

[0027] Example 2 This embodiment provides a method for preparing an alginate-chitosan composite hemostatic nonwoven fabric.

[0028] (1) Preparation of homogeneous spinning precursor solution: First, weigh 1.0 g of chitosan powder and 0.05 g of ethylenediamine-N,N′-disuccinic acid powder, disperse them together in 80 mL of deionized water, and stir to form a uniform suspension. Adjust the pH value to 8.0 using 1.0 M sodium hydroxide aqueous solution. Transfer the solution to a high-pressure reactor, introduce high-purity carbon dioxide gas, and make the pressure inside the reactor reach and stabilize at 2.0 MPa. Stir and react at 20 °C for 1.5 hours to obtain a carbamate-esterified chitosan / EDDS mixed mother liquor. Separately weigh 2.0 g of sodium alginate, dissolve it in 100 mL of deionized water, stir and degas under vacuum to obtain a sodium alginate solution. Under the condition of maintaining the pressure inside the reactor at 2.0 MPa, pump the sodium alginate solution into the reactor, mix it with the above mother liquor, and continue stirring for 30 minutes to obtain a homogeneous spinning precursor solution.

[0029] (2) Preparation of functionalized coagulation bath: Weigh 20.0g of calcium acetate and 1.0g of zinc sulfate and dissolve them in deionized water. Adjust the pH to 6.0 using glacial acetic acid, and finally bring the volume to 1L with deionized water.

[0030] (3) Wet spinning and fiber forming: The homogeneous spinning precursor solution prepared in step (1) is extruded through a spinneret with an 80 μm aperture at a flow rate of 0.1 mL / min and enters the coagulation bath prepared in step (2). The nascent fibers are drawn out after traveling 50 cm in the coagulation bath, and then washed with water, and stretched by 1.2 times during the washing process. The stretched fiber bundles are dried in an oven at 60 °C to obtain continuous filaments.

[0031] (4) Preparation and final treatment of nonwoven fabric: The dried continuous filaments were cut into short fibers with a length of 38 mm. A certain amount of short fibers were taken, opened, and combed to form a fiber web with a basis weight of 30 g / m². The fiber web was reinforced using a hydroentangling machine with a hydroentangling pressure set to 3.0 MPa. The hydroentangled nonwoven fabric was dried, cut, and sealed in packaging. Finally, it was sterilized by radiation using a cobalt-60 radiation source with an absorbed dose of 15 kGy to obtain the final product.

[0032] Example 3 This embodiment provides a method for preparing an alginate-chitosan composite hemostatic nonwoven fabric.

[0033] (1) Preparation of homogeneous spinning precursor solution: First, weigh 3.0 g of chitosan powder and 0.2 g of ethylenediamine-N,N′-disuccinic acid powder, disperse them together in 80 mL of deionized water, and stir to form a uniform suspension. Adjust the pH value to 8.5 using 1.0 M sodium hydroxide aqueous solution. Transfer the solution to a high-pressure reactor, introduce high-purity carbon dioxide gas, and make the pressure inside the reactor reach and stabilize at 4.0 MPa. Stir and react at 25 °C for 2.5 hours to obtain a carbamate-esterified chitosan / EDDS mixed mother liquor. Separately weigh 5.0 g of sodium alginate, dissolve it in 100 mL of deionized water, stir and degas under vacuum to obtain a sodium alginate solution. Under the condition of maintaining the pressure inside the reactor at 4.0 MPa, pump the sodium alginate solution into the reactor, mix it with the above mother liquor, and continue stirring for 60 minutes to obtain a homogeneous spinning precursor solution.

[0034] (2) Preparation of functionalized coagulation bath: Weigh 50.0g of calcium acetate and 5.0g of zinc acetate and dissolve them in deionized water. Adjust the pH to 5.0 using glacial acetic acid, and finally bring the volume to 1L with deionized water.

[0035] (3) Wet spinning and fiber forming: The homogeneous spinning precursor solution prepared in step (1) is extruded through a spinneret with a pore size of 120 μm at a flow rate of 0.5 mL / min and enters the coagulation bath prepared in step (2). The nascent fibers are drawn out after traveling 100 cm in the coagulation bath, and then washed with water, and stretched by 1.8 times during the washing process. The stretched fiber bundles are dried in an oven at 80 °C to obtain continuous filaments.

[0036] (4) Preparation and final treatment of nonwoven fabric: The dried continuous filaments were cut into short fibers with a length of 51 mm. A certain amount of short fibers were taken, opened, and combed to form a fiber web with a basis weight of 60 g / m². The fiber web was reinforced using a hydroentangling machine with a hydroentangling pressure set to 6.0 MPa. The hydroentangled nonwoven fabric was dried, cut, and sealed in packaging. Finally, it was sterilized by radiation using a cobalt-60 radiation source with an absorbed dose of 25 kGy to obtain the final product.

[0037] Comparative Example The difference between Comparative Example 1 and Example 1 is that in step (1), carbon dioxide gas was not introduced for pressurization during the preparation of the homogeneous spinning precursor solution. Instead, the chitosan / EDDS dispersion with a pH adjusted to 8.2 was directly mixed with the sodium alginate solution. The remaining steps and parameters were the same as in Example 1.

[0038] The difference between Comparative Example 2 and Example 1 is that the functionalized coagulation bath in step (2) does not use glacial acetic acid to adjust the pH to 5.5, but instead uses a neutral aqueous solution containing only 35.0 g / L calcium acetate and 3.0 g / L zinc sulfate (pH value of approximately 7.0). The remaining steps and parameters are the same as in Example 1.

[0039] The difference between Comparative Example 3 and Example 1 is that, in step (1), ethylenediamine-N,N′-disuccinic acid was not added when preparing the homogeneous spinning precursor solution. The remaining steps and parameters were the same as in Example 1.

[0040] The difference between Comparative Example 4 and Example 1 is that the functionalized coagulation bath in step (2) does not contain zinc sulfate. That is, the coagulation bath is an aqueous solution containing only 35.0 g / L calcium acetate, with the pH adjusted to 5.5 using glacial acetic acid. The remaining steps and parameters are the same as in Example 1.

[0041] Test Example 1: Evaluation of the homogeneity and stability of spinning precursor solutions Experimental steps Sample acquisition: 100 mL of liquid obtained from each of Examples 1, 2, and 3 after their respective S1 steps, and 100 mL of liquid obtained from Comparative Example 1 after the mixing step, were taken as the test samples.

[0042] Initial status evaluation: Within 5 minutes of sample preparation completion, immediately perform the following operations: (a) Visual observation: Place the sample in a transparent glass beaker and observe and record its macroscopic appearance against a white background, including clarity, color, and the presence of visible flocculent matter, gel particles, or precipitates.

[0043] (b) Turbidity measurement: Using a WGZ-200S turbidimeter, take an appropriate amount of sample and inject it into a standard cuvette, measure and record its initial turbidity value. Each sample is measured three times, and the average value is taken.

[0044] Stability test: Seal the remaining samples in glass bottles with caps and let them stand for 2 hours at room temperature of 20-25℃.

[0045] Final status evaluation: After standing for 2 hours, perform step 2 (a) appearance observation and (b) turbidity measurement on each sample again, and record the results.

[0046] The experimental data are shown in Table 1. Table 1 Results of tests on the homogeneity and stability of the spinning precursor solution Experimental results show that the spinning precursor solutions prepared in Examples 1-3 maintained a transparent and uniform appearance in the initial state and after standing for 2 hours, with their turbidity values ​​remaining at a low level and showing little variation. In contrast, the mixture prepared in Comparative Example 1 showed flocculent matter immediately after mixing and produced a large amount of precipitate after standing, with its turbidity value being significantly higher than that of the samples in Examples 1-3.

[0047] The differences in the above test results stem from whether carbon dioxide was used for chemical modification in the preparation method. In the preparation methods of Examples 1-3, chitosan first reacts in a pressurized carbon dioxide environment. Under these conditions, carbon dioxide molecules react chemically with the amino groups on the chitosan molecular chain to generate water-soluble carbamate groups. This chemical structural transformation causes the amino groups, which may have been protonated and positively charged in aqueous solution, to temporarily transform into negatively charged groups, thereby eliminating the electrostatic attraction between chitosan and the similarly negatively charged alginate. Therefore, the two polymers can be uniformly mixed at the molecular level to form a macroscopically transparent, homogeneous, and stable solution system.

[0048] In contrast, the preparation method of Comparative Example 1 did not include a carbon dioxide reaction step. In this case, the amino groups on the chitosan molecular chain retain their original chemical structure and charge properties. When directly mixed with a negatively charged alginate solution, a strong electrostatic interaction occurs between the positive and negative charges, instantly forming a water-insoluble polyelectrolyte complex, which precipitates from the solution as a large amount of flocculent material and precipitate. This phenomenon corresponds to the high turbidity and solution heterogeneity observed in Test Example 1, confirming that a homogeneous precursor solution for subsequent spinning cannot be obtained without the specific chemical reaction steps proposed in this invention.

[0049] Test Example 2: Wet Structural Integrity Test of Composite Nonwoven Fabrics Experimental steps Sample preparation: Rectangular strips with dimensions of 50mm × 10mm were cut from the final nonwoven fabrics prepared in Examples 1, 2, 3 and Comparative Example 2, respectively, along the same direction.

[0050] Sample wetting: Immerse each group of sample strips in a petri dish containing phosphate buffer solution (PBS, pH=7.4) and place them in a constant temperature water bath at 37°C for 30 minutes to wet them.

[0051] Qualitative observation: After wetting, carefully hold one end of each sample strip in the solution with tweezers and lift it vertically. Visually observe and record whether it breaks, disintegrates or deforms significantly.

[0052] Mechanical property testing: Unbroken wetted specimens were clamped in a universal testing machine equipped with a 10N sensor at a clamping distance of 20mm. The specimens were stretched at a tensile rate of 20mm / min until fracture. The tensile strength at break and elongation at break (%) were recorded. For samples that fractured in step 3, their wet strength was recorded as unmeasurable.

[0053] Data processing: Five samples were tested for each sample group, and the average value of the results was taken.

[0054] The experimental data are shown in Table 2. Table 2. Test results of wet mechanical properties of composite nonwoven fabric Experimental data show that the nonwoven fabric samples prepared in Examples 1, 2, and 3 all maintained their complete structural morphology after wetting, and their wet tensile breaking strength values ​​ranged from 0.67 MPa to 0.96 MPa. In contrast, the sample prepared in Comparative Example 2 disintegrated upon being lifted from the solution, and its measured wet tensile breaking strength value was significantly lower than that of the example samples.

[0055] In the preparation methods of Examples 1-3, an acidic coagulation bath with a pH of 5.0-6.0 was used during the spinning process. This acidic environment promotes the chemical decomposition of the carbamate-esterified chitosan entering the coagulation bath, restoring its original amino (-NH2) structure. Simultaneously, the restored amino group is protonated to a positively charged -NH3 group under acidic conditions. + Groups. These in-situ generated -NH3 + The group then reacts with the carboxyl group (-COO) on the adjacent, negatively charged alginate molecular chain. - Strong electrostatic interactions occur, forming a dense polyelectrolyte complex network within the calcium alginate gel network. This dual-network interpenetrating structure endows the composite fibers with a robust internal structure, enabling the final nonwoven fabric to maintain its structural integrity and mechanical strength in a wet state.

[0056] In the preparation method of Comparative Example 2, a neutral coagulation bath was used. Under neutral conditions, the decomposition rate of urethane-esterified chitosan is extremely low or nonexistent, thus the amino groups of chitosan cannot be effectively restored and protonated. This results in the failure to form the expected polyelectrolyte complex network between alginate and chitosan. The fiber structure mainly relies on a single gel network formed by alginate and calcium ions, which is relatively loose with weak intermolecular forces. Therefore, when the sample of Comparative Example 2 is wetted in an aqueous environment, due to the lack of a dense internal electrostatic complex network support, its structure cannot resist external stress, exhibiting extremely low wet strength and easy disintegration.

[0057] Test Example 3: Zinc Ion Sequential Release Performance Test of Composite Nonwoven Fabric Experimental steps Sample preparation and grouping: 0.1g of sample was accurately weighed from the final nonwoven fabrics prepared in Examples 1, 2, 3, and Comparative Examples 3 and 4, respectively, and 3 parallel samples were set up in each group.

[0058] Preparation of release medium: Prepare a phosphate buffer solution with a pH of 7.4 as the release medium.

[0059] In vitro release experiment: Each weighed sample was placed in a sterile Erlenmeyer flask containing 50 mL of PBS solution. After sealing all the flasks, they were placed in a constant temperature shaking incubator at 37°C and 100 rpm for shaking.

[0060] Sample collection: At preset time points (1, 8, 24, 48, 72 hours), 1.0 mL of supernatant was taken from each conical flask as the sample to be tested, and 1.0 mL of fresh PBS solution preheated to 37°C was immediately added to the conical flask to maintain a constant release volume.

[0061] Concentration determination: All collected samples were analyzed using inductively coupled plasma mass spectrometry to determine the mass concentration of zinc ions.

[0062] Data calculation: Based on the measured concentration, calculate the cumulative release rate (%) of zinc ions at each time point.

[0063] The experimental data are shown in Table 3. Table 3. Cumulative release rate test results of zinc ions in composite nonwoven fabrics (%) According to the test data in Table 3, the nonwoven fabric samples prepared in Examples 1, 2, and 3 exhibited similar zinc ion release patterns: approximately 20%-30% of the total load was released within the initial 8 hours, followed by a slower release rate, resulting in a continuous and slow release process over 72 hours. In contrast, the sample prepared in Comparative Example 3 released over 68% of the zinc ions within 1 hour and over 85% within 8 hours, demonstrating an explosive release. Comparative Example 4 served as a blank control, and no zinc ion release was detected throughout the entire test period.

[0064] In the preparation methods of Examples 1-3, ethylenediamine-N,N′-disuccinic acid, a type of Zn, was pre-uniformly dispersed in the homogeneous spinning precursor solution. 2+ An ion-selective chelating agent with high selective affinity. During wet spinning, when the fiber enters a Zn-containing... 2+During the coagulation bath, these EDDS molecules, pre-distributed in the polymer matrix, can efficiently capture and react with Zn. 2+ This forms chemically stable chelates. Therefore, the vast majority of zinc ions are fixed within the fiber in a chelated state, rather than through simple physical adsorption. This chemical bonding inhibits the diffusion of zinc ions from the fiber matrix to the external medium, reducing the release rate compared to Zn. 2+ The dissociation equilibrium of the -EDDS chelate controls the long-term, sustained release of zinc ions.

[0065] In Comparative Example 3, the ion-selective chelating agent EDDS was not added. Therefore, during the coagulation process, Zn entered the fiber interior... 2+ The zinc ions are temporarily immobilized only through physical adsorption or by forming weak ionic bonds with functional groups (such as carboxyl groups) on the polymer chain. This non-specific and unstable binding mechanism cannot effectively bind zinc ions. When the sample is immersed in the release medium, due to the huge concentration gradient inside and outside, these physically trapped zinc ions can rapidly and unimpededly diffuse into the solution, resulting in a large-scale explosive release in the early stages of the experiment. This result confirms that the ion-selective chelating agent plays a decisive role in the ion-release system proposed in this invention.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An alginate chitosan composite hemostatic nonwoven fabric, characterized by, The non-woven fabric is composed of composite fibers, which are made of the following components by weight: alginate: 60-85 parts; Chitosan: 15-40 parts; to Zn 2+ ions with a higher selectivity affinity than to Ca 2+ ions with a higher selectivity affinity than to Ca chelating agent: 0.1-2.0 parts; wherein the alginate and the chitosan are present in the form of a polyelectrolyte complex, and the ion-selective chelator chelates Zn 2+ and are uniformly distributed in the composite fiber.

2. The alginate chitosan composite hemostatic nonwoven fabric according to claim 1, characterized by, The ion-selective chelating agent is ethylenediamine-N,N'-disuccinic acid.

3. A method for preparing the alginate chitosan composite hemostatic nonwoven fabric according to claim 1 or 2, characterized by, The method comprises the following steps: S1: preparing a homogeneous spinning precursor solution: dissolving chitosan, and Zn 2+ ions with higher selectivity affinity than Ca 2+ ions, in water, and then reacting in a carbon dioxide environment with a pressure of 2.0-4.0 MPa to generate carbamate chitosan; and mixing the carbamate chitosan with an aqueous alginate solution; S2: wet spinning is performed: the homogeneous spinning precursor solution is extruded through a spinneret into a coagulation bath having a pH of 5.0-6.0 and containing Ca 2+ and Zn 2+ , which causes the urethanized chitosan to decompose and revert to chitosan, while the alginate crosslinks with Ca 2+ , the chitosan and the alginate form a polyelectrolyte complex, and the ion-selective chelating agent traps Zn 2+ inside the fiber; S3: post-processing forming: washing, stretching and drying the composite fibers to obtain continuous filaments; then cutting the continuous filaments into short fibers and preparing a non-woven fabric by a water jet method.

4. The method of claim 3, wherein, In the S1, when preparing the homogeneous spinning precursor solution, the mass concentrations of the components are as follows: the mass concentration of alginate is 2.0%-5.0% w / v, the mass concentration of chitosan is 1.0%-3.0% w / v, and the mass concentration of the ion-selective chelating agent is 0.05%-0.2% w / v.

5. The method according to claim 3 or 4, characterized in that, In the S1, the reaction in the carbon dioxide environment is carried out under the following conditions: reaction at 20-25℃ for 1.5-2.5 hours.

6. The method of claim 3, wherein, The coagulation bath in the S2 is composed of an aqueous solution of calcium acetate, zinc sulfate or zinc acetate, and acetic acid.

7. The method of claim 6, wherein, In the coagulation bath, the mass concentration of calcium acetate is 2.0%-5.0% w / v, and the mass concentration of zinc sulfate or zinc acetate is 0.1%-0.5% w / v.

8. The method of claim 3, wherein, In the S3, the stretching ratio of the stretching is 1.2-1.8 times.

9. The method of claim 3, wherein, In the S3, the water jet pressure used in the water jet method is 3.0-6.0 MPa.

10. The method of claim 3, wherein, The preparation method further comprises a final sterilization step, which adopts cobalt-60 radiation sterilization with an absorbed dose of 15-25 kGy.

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