Chitosan-based antibacterial fiber and fabric as well as preparation method and application of chitosan-based antibacterial fiber and fabric

Abstract

The invention discloses a chitosan-based antibacterial fiber, a chitosan-based antibacterial fabric, a preparation method of the chitosan-based antibacterial fiber and application of the chitosan-based antibacterial fabric. The preparation method comprises the following steps: firstly, carrying out wet spinning to obtain chitosan fibers, and meanwhile, carrying out self-assembly on the surfaces of the chitosan fibers to form a nano-composite functional layer consisting of polydopamine, reduced graphene oxide and nano-silver; secondly, the chitosan composite fibers are immersed in a polyethylene glycol derivative solution containing aldehyde groups, chitosan amino groups on the surfaces of the fibers and the aldehyde groups in the acid solution are subjected to a cross-linking reaction, and a Schiff base cross-linked network is formed; and finally, carrying out surface coating on the cross-linked chitosan composite fiber by using a solution containing low-molecular-weight chitosan and a therapeutic drug to form a drug outer layer, so as to obtain the chitosan-based antibacterial fiber. The chitosan-based antibacterial fiber and fabric disclosed by the invention integrate multiple functions of long-acting antibiosis, pH-responsive drug release, anticoagulation, healing promotion and the like, and provides an artificial blood vessel and an intravascular stent membrane covering material which can simultaneously solve clinical problems of infection, thrombus, intimal hyperplasia and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological materials, and relates to a chitosan-based antibacterial fiber, a fabric and a preparation method and application thereof. BACKGROUND

[0002] Artificial blood vessels and vascular covered stents are key implants for the treatment of cardiovascular diseases, and the main materials thereof are usually polyethylene terephthalate (PET) or expanded polytetrafluoroethylene (ePTFE). Although this stent is widely used, such traditional materials still face many severe challenges in clinical practice. First, the blood compatibility thereof is poor, and the material surface easily causes platelet adhesion and thrombosis, affecting the long-term patency rate of the device. Second, the surface of the traditional material is not conducive to the adhesion and proliferation of vascular endothelial cells, and the endothelialization process is slow, and a physiological antithrombotic inner wall cannot be formed. Third, the inherent infection risk is extremely high, and the material itself does not have antibacterial properties, and once contaminated with bacteria, it is easy to form a biofilm that is difficult to remove with conventional antibiotics, leading to a catastrophic implant-related infection.

[0003] To solve the above problems, researchers have explored various surface modification strategies, among which graphene and its derivative coatings show great potential and can improve the blood compatibility, antibacterial properties and mechanical properties of the material to some extent. However, these strategies are essentially "surface coating" techniques that perform post-treatment on inert substrates, and have the following inherent limitations: 1) the interfacial bonding force between the coating and the substrate is a weak link in its long-term stability, and there is a risk of peeling off; 2) the function of the coating is usually continuous and non-selective, and lacks the "intelligence" of self-regulation according to the physiological state of the body, which may have a negative impact when not necessary; 3) it is extremely difficult to integrate multiple functions on one coating and achieve their time sequence synergy.

[0004] A Chinese patent with application number CN201810938556.3 discloses a preparation method of a multifunctional vascular stent and its application. The preparation method is as follows: first, a dopamine coating is prepared on the surface of the vascular stent through dopamine self-polymerization; then, heparin is loaded in chitosan-functionalized graphene oxide, and the heparin-loaded graphene oxide is further fixed on the surface of the vascular stent with the dopamine coating; finally, the vascular stent is immersed in a rapamycin solution to adsorb and load rapamycin, thereby obtaining a multifunctional vascular stent. The multifunctional vascular stent has good antibacterial properties, anticoagulant properties, anti-proliferative properties and pro-endothelial cell growth properties, and can inhibit clinical complications of stent implantation from multiple pathways, thereby improving the application effect of the vascular stent. However, in this patent, graphene and chitosan are fixed on the already formed polydopamine coating through subsequent steps, and the long-term antibacterial properties of chitosan and graphene may gradually weaken with the degradation of chitosan.

[0005] A Chinese patent with the application number CN202211106505.7 discloses a functional coating for the surface of a vascular medical device and a preparation method thereof. The preparation method is as follows: first, a polylysine (PLL) coating is prepared on the surface of a biomaterial, a polydopamine coating is formed through a dopamine self-polymerization reaction, and then the PLL coating is formed by reacting in a PLL solution; second, a reduced graphene oxide (rGO) solution is prepared and mixed with a heparin sodium solution, and after centrifugal drying, the heparin-loaded reduced graphene oxide solution (HerGO) is re-dispersed; third, the PLL coating material is adsorbed in the HerGO solution, and after drying, a single-layer heparin-loaded reduced graphene oxide coating is obtained; finally, the PLL and HerGO solutions are alternately immersed to obtain a multi-layer heparin-loaded reduced graphene oxide coating. The coating prepared by the present application has excellent anticoagulant properties, good biocompatibility, and certain antibacterial ability, and is suitable for surface modification of various biomaterials and medical devices. Although the patent significantly improves the anticoagulant properties and biocompatibility of the material, HerGO is fixed on the surface of the already formed polydopamine coating through subsequent steps, rather than inside the coating. In addition, PLL has good short-term antibacterial performance, but long-term antibacterial durability needs to be further verified, especially in complex biological environments.

[0006] Therefore, there is an urgent need in the art for a new design idea, i.e. no longer relying on surface modification of traditional materials, but directly designing and manufacturing a functional biological fiber material that has multiple biological functions and can intelligently respond to pathological microenvironments. This material can inherently and integrally combine structural support with biological functions, fundamentally solving the bottleneck problem of the prior art. SUMMARY

[0007] Due to the above-mentioned defects of the prior art, the present application provides a chitosan-based antibacterial fiber and fabric integrating long-acting antibacterial, pH-responsive drug release, anticoagulant, and wound healing functions, which is prepared by a "spinning-in-situ self-assembly" process and a two-step surface modification method, and provides a new generation of artificial blood vessels and vascular stent covering materials that can simultaneously solve key clinical problems such as infection, thrombosis, and intimal hyperplasia.

[0008] To achieve the above-mentioned purpose, in a first aspect, the present application provides a chitosan-based antibacterial fiber, comprising:

[0009] a fiber core composed of chitosan;

[0010] a functional inner layer, which is wrapped on the surface of the fiber core and is composed of a nanocomposite layer of polydopamine, reduced graphene oxide, and nano-silver;

[0011] Cross-linking network: pH-sensitive Schiff base cross-linking network formed by the reaction of chitosan and aldehyde group-containing polyethylene glycol derivative on the surface of the fiber core and the functional inner layer;

[0012] Drug outer layer: degradable capping layer composed of low molecular weight chitosan and therapeutic drugs loaded on the outermost surface of the fiber.

[0013] Further, the therapeutic drug is one or more of an anticoagulant, an anti-proliferative drug, and a vascular endothelial growth factor.

[0014] In a second aspect, the present application provides a preparation method of chitosan-based antibacterial fiber, which prepares the chitosan-based antibacterial fiber as described above, comprising the following steps:

[0015] S1, dissolving chitosan, graphene oxide, soluble silver salt and dopamine hydrochloride in an acidic solvent to form a spinning dope; extruding the spinning dope to an alkaline coagulation bath by wet spinning; under the alkaline environment of the coagulation bath, dopamine undergoes self-polymerization, and graphene oxide is reduced to reduced graphene oxide, and silver ions are reduced to nano-silver, obtaining chitosan fiber at the same time, and self-assembling a nano-composite functional layer composed of polydopamine, reduced graphene oxide and nano-silver on the surface of the chitosan fiber;

[0016] S2, immersing the chitosan composite fiber prepared in step S1 in an acidic solution containing an aldehyde group-containing polyethylene glycol derivative, and the amine groups on the surface of the fiber cross-link with the aldehyde groups in the acidic solution to form a Schiff base cross-linking network;

[0017] S3, coating the chitosan composite fiber cross-linked in step S2 with a solution containing low molecular weight chitosan and one or more therapeutic drugs, and forming a drug outer layer after drying to obtain the chitosan-based antibacterial fiber.

[0018] Further, in step S1, the pH value of the spinning dope is 3.5-4.5; the alkaline coagulation bath is a sodium hydroxide solution or a mixed solution of sodium hydroxide and ethanol; in step S2, the pH value of the acidic solution is 5-6.

[0019] Further, in step S1, the acidic solvent is 2-5 vol% glacial acetic acid aqueous solution; the concentration of chitosan is 2-10% (w / v); the concentration of graphene oxide is 0.5-5 wt%; the silver salt is silver nitrate, and the concentration is 0.5-10 wt%; the concentration of dopamine hydrochloride is 5-20 wt%; the alkaline coagulation bath is 3-10 wt% sodium hydroxide dissolved in an ethanol / water mixed solvent, wherein the volume ratio of ethanol to water is (50-90):(50-10).

[0020] Further, in the step S2, first, the CHO-PEG-CHO with a molecular weight of 2-5 kDa is dissolved in an acetic acid-sodium acetate buffer to obtain a PEG-CHO crosslinking solution with a concentration of 0.5-5 wt%; then the dry chitosan composite fiber bundle is loosely immersed in the crosslinking solution and placed in a constant-temperature water bath shaker at 20-60°C, and the reaction is shaken at a low speed for 0.5-4 hours; after the reaction is completed, the fiber bundle is taken out and rinsed with the buffer and deionized water; and finally, the fiber bundle is freeze-dried.

[0021] Further, in the step S3, the drug-loaded solution is a uniform emulsion or suspension, which comprises a buffer with a pH of 5-6, 1000-5000 molecular weight chitosan with a concentration of 0.5-3.0 wt%, and a therapeutic drug.

[0022] Further, in the step S3, the surface coating method is spraying, dipping or spin coating.

[0023] In a third aspect, the application provides a chitosan-based antibacterial fabric, which is made by weaving, knitting or non-woven process of the chitosan-based antibacterial fiber as described above.

[0024] In a last aspect, the application provides an application of the chitosan-based antibacterial fabric, and the chitosan-based antibacterial fabric as described above is used as a covering material of an artificial blood vessel or a blood vessel covered stent.

[0025] The above technical solution is only one feasible technical solution of the application, and the protection scope of the application is not limited to this, and those skilled in the art can reasonably adjust the specific design according to actual needs.

[0026] Compared with the prior art, the application has the following advantages:

[0027] (1) The application constructs a nano functional layer on the surface of the fiber during the fiber forming process through an innovative "spinning-in-situ self-assembly" process, so that the long-term background function (such as antibacterial) and the intelligent drug release triggered by pathological signals (such as anticoagulation and anti-proliferation) are inherently and stably combined in a single fiber system.

[0028] (2) The intelligent biological fiber designed by the application has the advantages of a drug graded release mechanism triggered by pH value change. The mechanism realizes the transformation from "silent protection" to "intelligent attack" by time-coupling the controllable cleavage of chemical bonds with the physical form change of polymer chains. In a normal physiological environment (pH ≈ 7.4), the Schiff base (Imine bond) crosslinking network formed by the reaction of the chitosan amine group on the fiber surface and the aldehyde group-containing polyethylene glycol derivative is chemically stable. The Schiff base crosslinking network is used for enhancing the mechanical properties of the fiber and as an intelligent gate to realize the intelligent release of the targeted drug. The complete network is like a dense "chemical lock" that physically locks the therapeutic drugs loaded thereon and further inhibits the exudation of the silver nanoparticles in the functional inner layer below, and meanwhile, the polyethylene glycol segments in the network endow the fiber surface with excellent anti-biofouling properties, so that the fiber as a whole is in a stable "locking and protection" state.

[0029] When the implantation site is acidified (pH < 6.8) due to pathological reasons such as bacterial infection, ischemia or inflammation, the decrease of the pH value becomes the key signal to activate the whole system. First, the acid environment catalyzes the rapid hydrolysis of the Schiff base bond, leading to the destruction of the crosslinking network structure, and the "chemical lock" is opened. This process directly triggers the first stage response: the outer layer of the originally locked drug loses the restraint, so that the therapeutic drugs (such as heparin, rapamycin, etc.) loaded therein are released in an explosive manner in the lesion area, thereby forming a local high drug concentration in a short time and realizing the rapid intervention on the acute pathological state. Then, with the breaking of the Schiff base bond, the chitosan amine group in the fiber matrix is re-exposed and protonated into positively charged ammonium groups (~NH3 + ) in the acid environment. Strong electrostatic repulsion occurs between a large number of positive charges, driving the whole fiber core to swell significantly. The swelling of the fiber makes the internal network loose, which opens up a channel for the release of silver ions from the silver nanoparticles buried in the functional inner layer, thereby triggering the second stage response: the release rate of silver ions is significantly accelerated, providing the lesion with sustained and long-acting broad-spectrum antibacterial ability to eliminate residual pathogens.

[0030] (3) In order to solve the fundamental problems of poor interface stability, single function and lack of intelligent response of the substrate and functional coating of implantable medical devices (such as artificial blood vessels and covered stents) in the prior art, the chitosan-based antibacterial fiber and fabric provided by the present invention are advanced biomaterials whose mechanical properties and drug release kinetics can be precisely controlled. They integrate long-acting antibacterial (inner layer Ag / rGO), intelligent drug release (middle layer Schiff base lock), and targeted therapy (outer layer drug) into one, and can be used to prepare a new generation of artificial blood vessels and vascular covered stents that can solve key clinical problems such as infection, thrombosis and intimal hyperplasia at the same time.

[0031] (4) The preparation method of the present invention is ingenious, highly controllable and easy to scale up, and has good application prospects. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0033] The execution order of actions, steps, etc. in the apparatus and method shown in the claims can be implemented in any order, unless a specific order is explicitly specified, and as long as the output of the preceding processing is not used in the subsequent processing.

[0034] This invention first provides a method for preparing chitosan-based antibacterial fibers, comprising the following steps:

[0035] S1. Chitosan, graphene oxide, soluble silver salt, and dopamine hydrochloride are dissolved together in an acidic solvent to form a spinning solution; the spinning solution is extruded into an alkaline coagulation bath by wet spinning; under the alkaline environment of the coagulation bath, dopamine undergoes self-polymerization, and graphene oxide is reduced to reduced graphene oxide and silver ions are reduced to nano-silver, thereby obtaining chitosan fibers. At the same time, a nanocomposite functional layer composed of polydopamine, reduced graphene oxide, and nano-silver is self-assembled on its surface.

[0036] S2. The chitosan composite fiber obtained in step S1 is immersed in an acidic solution of polyethylene glycol derivative containing aldehyde groups. The chitosan amine groups on the fiber surface undergo a cross-linking reaction with the aldehyde groups in the acidic solution to form a Schiff base cross-linking network.

[0037] S3. The chitosan composite fiber cross-linked in step S2 is coated with a solution containing low molecular weight chitosan and one or more therapeutic drugs. After drying, a drug outer layer is formed, resulting in chitosan-based antibacterial fiber.

[0038] The prepared chitosan-based multifunctional antibacterial fiber has a structure including, from inside to outside, successively:

[0039] The fiber core is mainly composed of chitosan, providing basic mechanical support and biocompatibility.

[0040] The functional inner layer is a nanocomposite layer composed of polydopamine, reduced graphene oxide and nanosilver, wrapped on the surface of the fiber core, providing long-acting antibacterial, conductive and enhanced functions.

[0041] The cross-linking network is a pH-sensitive Schiff base cross-linking network formed by the reaction of chitosan and aldehyde group-containing polyethylene glycol derivatives, permeating on the surface layer of the fiber core and the functional inner layer, used for enhancing mechanical properties and as a smart gate.

[0042] The drug outer layer is a degradable capping layer composed of low molecular weight chitosan and therapeutic drugs, loaded on the outermost surface of the fiber, used to achieve burst release of targeted drugs.

[0043] The chitosan-based antibacterial fabric made by weaving, knitting or non-woven process of the above-mentioned chitosan-based antibacterial fiber can be used as a covering material for artificial blood vessels or covered stent.

[0044] In the following, the technical solutions of the present application are described in detail with specific examples.

[0045] Examples

[0046] Experimental materials and equipment:

[0047] Chemical reagents: chitosan (degree of deacetylation 92%, viscosity average molecular weight 160 kDa), analytical grade glacial acetic acid, graphene oxide (GO) aqueous dispersion (concentration 4 mg / mL, flake diameter 0.5-3 μm), silver nitrate (AgNO3, AR grade), dopamine hydrochloride (DA·HCl, 98%), sodium hydroxide (NaOH, AR grade), anhydrous ethanol (AR grade), aldehyde-polyethylene glycol-aldehyde (CHO-PEG-CHO, molecular weight 2000 Da), sodium acetate (anhydrous, AR grade), low molecular weight water-soluble chitosan (Mw 15 kDa), sirolimus (>99%), acetone (AR grade), phosphate buffered saline (PBS), deionized water (resistivity 18.2 MΩ·cm).

[0048] Main equipment: wet spinning device (including precision syringe pump, stirring liquid storage tank, spinneret (pore diameter 100 μm), coagulation bath tank, guide and traction roller, winding device), magnetic stirrer, ultrasonic cleaner, freeze dryer, digital constant temperature water bath, high precision electronic balance, pH meter, spraying device (such as laboratory pneumatic spray gun).

[0049] Step 1: Precise preparation of acidic spinning dope (100 mL system)

[0050] Chitosan-based solution preparation: In a 250 mL clean beaker, add 80 mL of deionized water. Under continuous magnetic stirring, slowly add 2.0 mL of glacial acetic acid. After the acetic acid is completely dispersed, slowly add 3.0 g of chitosan powder in batches. Continue stirring for about 12 hours until a clear, yellowish viscous solution without insoluble particles is formed.

[0051] Functional component addition:

[0052] Graphene oxide (GO) dispersion: To the above chitosan-based solution, slowly add 10 mL of GO water dispersion (4 mg / mL, i.e. add 40 mg of GO). After the addition is complete, place the mixture in an ice water bath and use a probe-type ultrasonic instrument to treat it for 30 minutes (power 200 W, work 5 seconds, intermittent 3 seconds) to ensure uniform dispersion of GO in the viscous chitosan matrix, forming a stable black suspension.

[0053] Silver salt and dopamine dissolution: Place the beaker in a light-proof environment (such as wrapped with aluminum foil), and add 0.2 g of silver nitrate (AgNO3) and 0.5 g of dopamine hydrochloride (DA·HCl) in sequence. Continue to stir in the dark for 2 hours to ensure complete dissolution of all solids. At this time, the solution should remain dark brown-black and have no precipitate.

[0054] Defoaming and maturation: Seal the finally prepared spinning dope and place it in a 4°C refrigerator for 24 hours for defoaming and maturation to improve the stability of the spinning process. The final determination of the dope pH value should be between 3.5~4.0. It was found that a similar spinning effect could be obtained when the pH value of the dope was between 3.5~4.5.

[0055] Step 2: Wet spinning and in-situ surface self-assembly

[0056] Coagulation bath preparation: In the coagulation bath tank of the spinning device, prepare 10 L of coagulation bath. The composition of the coagulation bath is: 50 g / L of sodium hydroxide (5 wt%) dissolved in a mixed solvent of ethanol / water (volume ratio 70:30). Maintain the coagulation bath temperature at 25°C.

[0057] Spinning process parameter setting:

[0058] Load the matured spinning dope into the liquid storage tank of the spinning device.

[0059] Injection pump push rate: 15 mL / h.

[0060] Spinneret and coagulation bath liquid surface distance: 2 cm.

[0061] Distance between the first guide roller and the spinneret: 40 cm.

[0062] Traction rate (winding rate): 12 m / min.

[0063] Spinning and In-situ Reaction: The spinning device is started. The acidic spinning solution is forced through the spinneret into the alkaline coagulation bath. At the moment of contact, the following concerted reaction occurs:

[0064] Chitosan loses its protons as the pH increases, and quickly solidifies to form a fibrous core.

[0065] Dopamine undergoes rapid oxidative polymerization under alkaline conditions to form polydopamine (PDA).

[0066] During polymerization, the PDA synchronously reduces GO to rGO with better conductivity and converts Ag... + In-situ restoration to Ag 0 Nanoparticles (AgNPs).

[0067] The resulting PDA / rGO / AgNPs complex firmly "grows" on the surface of the nascent chitosan fibers through the strong adhesion of PDA, forming a black functional inner layer with a thickness of about 30~50 nm.

[0068] Post-processing: The continuously spun fibers are fully reacted and solidified in a coagulation bath through multiple guide rollers, and then drawn out of the liquid surface. The fibers are then cleaned online using a deionized water spray system to remove residual alkali and byproducts. Finally, the cleaned fibers are evenly wound onto a spool. The entire spool is soaked in deionized water for 24 hours (with water changes three times), then pre-frozen in a ~80°C freezer, and finally transferred to a freeze dryer for 48 hours to obtain a dried functional fiber bundle.

[0069] Step 3: Construction of Schiff base crosslinking network

[0070] Preparation of cross-linking solution: Prepare an acetate-sodium acetate buffer (0.1 M) with a pH of 5.5. Weigh 2.0 g of CHO-PEG-CHO (Mw 2 kDa) and dissolve it in 100 mL of this buffer to obtain a 2 wt% PEG-CHO cross-linking solution.

[0071] Crosslinking reaction: Loosely immerse the dried functional fiber bundles in the above crosslinking solution, ensuring that all fibers are fully wetted. Place the container in a constant temperature water bath shaker at 37°C and shake at a low speed of 30 rpm for 2 hours.

[0072] Cleaning and Drying: After the reaction, the fiber bundles were removed and rinsed three times with a large amount of pH 5.5 buffer solution to remove unreacted PEG~CHO. Subsequently, they were rapidly rinsed with deionized water to remove buffer salts. Finally, the fibers were freeze-dried again. At this point, the fibers showed a significant improvement in mechanical properties (such as wet strength).

[0073] Step 4: Spraying and constructing the drug-loaded outer layer

[0074] Drug loading solution preparation: Prepare a buffer solution with a pH of 5.5. In this buffer solution, first dissolve 1.0 wt% of low molecular weight water-soluble chitosan (Mw 15 kDa). After complete dissolution, add 0.2 wt% of rapamycin (which can be pre-dissolved with a small amount of acetone before addition) and continue stirring to form a homogeneous emulsion or suspension. Rapamycin is used as an example of the loaded drug here, but it is not limited to this single drug component. The loaded therapeutic drugs can be flexibly combined with anticoagulants, antiproliferative agents, or healing-promoting drugs according to clinical needs to achieve personalized and precise treatment strategies.

[0075] Spray coating process: The cross-linked, dried fiber bundle is fixed on a rotatable cylindrical fixture. The fixture is started and slowly rotated at a rate of 10 rpm. Using a laboratory pneumatic spray gun, the drug-loaded solution is uniformly sprayed onto the surface of the rotating fiber bundle. The spraying distance is approximately 15 cm, and the air pressure is 0.1 MPa. A "multi-layer thin spraying" strategy is adopted, after each layer is sprayed, it is dried with cold air for about 1 minute before the next layer is sprayed, until a uniform white drug film with a thickness of approximately 300 nm is formed on the fiber surface. Of course, in addition to spraying, other coating methods such as dip coating or spin coating can also be used for surface coating.

[0076] Final drying: After spraying, the fiber bundles with the drug outer layer are dried in a vacuum drying oven at 30°C for 24 hours to completely remove the solvent and ensure the stability of the drug layer.

[0077] Under normal physiological conditions (pH≈7.4), the Schiff base cross-linking network formed by the reaction of chitosan amino groups on the fiber surface with aldehyde-containing polyethylene glycol derivatives remains chemically stable, keeping the fiber as a whole in a stable "locked-in and protected" state. When the implantation site becomes acidic (pH<6.8) due to pathological reasons such as bacterial infection, ischemia, or inflammation, the acidic environment first catalyzes the rapid hydrolysis of Schiff base bonds, leading to the destruction of the cross-linking network structure and the "chemical lock" being opened. This process directly triggers the first stage of response: the previously locked outer layer of the drug loses its restraint, causing the loaded therapeutic drugs (such as heparin, rapamycin, etc.) to be released explosively in the lesion area, thereby forming a high local drug concentration in a short time and achieving rapid intervention in the acute pathological state. Subsequently, with the breakage of the Schiff base bonds, the chitosan amino groups in the fiber matrix are re-exposed and protonated into positively charged ammonium groups in the acidic environment. The strong electrostatic repulsion between the large number of positive charges drives the entire fiber core to undergo significant physical swelling. The swelling of the fibers loosens their internal network, which opens up channels for the release of silver ions from the nanosilver nanoparticles embedded deep within the functional inner layer, thereby triggering a second-stage response: the release rate of silver ions is significantly accelerated, providing the lesion with continuous, long-lasting, broad-spectrum antibacterial ability to eliminate residual pathogens.

[0078] In summary, this invention provides a chitosan-based antibacterial fiber and fabric that integrates multiple functions such as long-lasting antibacterial properties, pH-responsive drug release, anticoagulation, and healing promotion. It is prepared through a "spinning-in-situ self-assembly" process and a two-step surface modification method, providing a new generation of artificial blood vessels and vascular stent coating materials that can simultaneously solve key clinical problems such as infection, thrombosis, and intimal hyperplasia.

[0079] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0080] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A chitosan-based antibacterial fiber, characterized by, The application relates to a chitosan-based antibacterial fiber, which comprises the following parts: a fiber core composed of chitosan; a functional inner layer composed of a nanocomposite layer of polydopamine, reduced graphene oxide and nano-silver, which is wrapped on the surface of the fiber core; a cross-linking network composed of a pH-sensitive Schiff base cross-linking network formed by the reaction of chitosan and an aldehyde group-containing polyethylene glycol derivative, which penetrates the surface layer of the fiber core and the functional inner layer; and a drug outer layer composed of a degradable capping layer of low-molecular-weight chitosan and therapeutic drugs, which is loaded on the outermost surface of the fiber. The therapeutic drugs are one or more of an anticoagulant, an anti-proliferative drug and a vascular endothelial growth factor. The application further discloses a preparation method of the chitosan-based antibacterial fiber. In step S1, the pH value of the spinning dope is 3.5-4.5; the alkaline coagulation bath is a sodium hydroxide solution or a mixed solution of sodium hydroxide and ethanol; and in step S2, the pH value of the acid solution is 5-6. In step S1, the acid solvent is a 2-5vol% acetic acid aqueous solution; the concentration of the chitosan is 2-10% (w / v); the concentration of the graphene oxide is 0.5-5 wt%; the silver salt is silver nitrate, and the concentration is 0.5-10 wt%; the concentration of the dopamine hydrochloride is 5-20 wt%; and the alkaline coagulation bath is prepared by dissolving 3-10 wt% sodium hydroxide in an ethanol / water mixed solvent, wherein the volume ratio of ethanol to water is (50-90):(50-10).

2. The chitosan-based antibacterial fiber of claim 1, wherein the chitosan-based antibacterial fiber is characterized by, In step S2, CHO-PEG-CHO with a molecular weight of 2-5kDa is first dissolved in an acetic acid / sodium acetate buffer to obtain a PEG-CHO cross-linking solution with a concentration of 0.5-5 wt%; 3. A method for preparing a chitosan-based antibacterial fiber, characterized by, Then, the dry chitosan composite fiber bundle is immersed in the cross-linking solution and placed in a constant-temperature water bath shaker at 20-60 DEG C, and the reaction is carried out at a low speed for 0.5-4 hours; after the reaction is completed, the fiber bundle is taken out and rinsed with the buffer and deionized water; and finally, the fiber bundle is freeze-dried. ​ ​ ​ 4. The method for preparing chitosan-based antibacterial fibers according to claim 3, characterized in that, ​ 5. The method for preparing chitosan-based antibacterial fibers according to claim 4, characterized in that, ​ 6. The method for preparing chitosan-based antibacterial fibers according to claim 4, characterized in that, ​ ​ 7. A method for preparing chitosan-based antibacterial fibers according to claim 3 or 4, characterized in that, The drug-loaded solution in the step S3 is a uniform emulsion or suspension, including a buffer solution with pH 5-6, 1000-5000 molecular weight chitosan with a concentration of 0.5-3.0 wt%, and a therapeutic drug.

8. A method for preparing chitosan-based antibacterial fibers according to claim 3 or 4, characterized in that, The surface coating method in the step S3 is spraying, dipping or spin coating.

9. A chitosan-based antibacterial fabric, characterized by, The chitosan-based antibacterial fiber is made by weaving, knitting or non-woven process.

10. Use of a chitosan-based antibacterial fabric, characterized in that, The chitosan-based antibacterial fabric in claim 9 is used as a coating material of artificial blood vessels or vascular covered stents.