Nano-silver ion sustained-release antibacterial wound dressing

Abstract

This invention discloses a nano-silver ion sustained-release antibacterial wound dressing, relating to the field of medical materials technology, comprising the following formulation in parts by weight: polyvinyl alcohol, 30–80 parts; sodium carboxymethyl cellulose, 5–30 parts; sodium hyaluronate, 0.2–5 parts; glycerin, 2–20 parts; sodium alginate, 3–25 parts; calcium chloride, 0.2–6 parts; nano-silver, 0.05–2 parts; sodium citrate, 0.1–3 parts; purified water, 200–1200 parts. This invention achieves continuous and gradual release of silver ions by constructing a stable polymer film-forming structure and a sustained-release network formed by ion cross-linking within the dressing, thus confining the nano-silver distribution within the gel structure. While ensuring effective antibacterial performance, it significantly reduces the irritation risk associated with instantaneous release, prolongs the antibacterial effect time, and improves the stability and safety of the dressing during use, making it suitable for applications requiring long-term wound protection and infection control.

Description

Technical Field

[0001] This invention relates to the field of medical materials technology, specifically to a nano-silver ion sustained-release antibacterial wound dressing. Background Technology

[0002] Wound dressings are widely used for skin wound protection and infection control. Among them, silver-containing antibacterial dressings are widely used because they have a broad-spectrum inhibitory effect on a variety of bacteria.

[0003] In existing technologies, a common practice is to directly load silver ions or nano-silver into the dressing matrix, so that the antibacterial effect can be achieved by contacting wound exudate.

[0004] However, such dressings generally suffer from the problem of uncontrollable silver ion release rate. They often release rapidly in the early stages of use, resulting in a short duration of antibacterial effect and a significant decrease in antibacterial effect in the later stages. At the same time, the instantaneous high concentration of silver ions may also irritate newly formed tissue and affect wound healing.

[0005] In addition, the antibacterial components in some existing dressings are loosely integrated with the matrix structure and lack a stable spatial confinement structure, resulting in poor storage stability and consistency in use, making it difficult to meet the dual requirements of safety and long-lasting effect in clinical practice. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a nano-silver ion sustained-release antibacterial wound dressing to solve the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a nano-silver ion sustained-release antibacterial wound dressing, comprising the following formula in parts by weight:

[0009] Polyvinyl alcohol, 30–80 parts;

[0010] Sodium carboxymethyl cellulose, 5–30 parts;

[0011] Sodium hyaluronate, 0.2–5 parts;

[0012] Glycerin, 2–20 parts;

[0013] Sodium alginate, 3–25 parts;

[0014] Calcium chloride, 0.2–6 parts;

[0015] Nano silver, 0.05–2 parts;

[0016] Sodium citrate, 0.1–3 parts;

[0017] Purified water, 200–1200 parts.

[0018] To further optimize this technical solution, the nano-silver is obtained by a combination of wet physical dispersion and chemical reduction, including:

[0019] Deionized water was selected as the dispersion medium. Soluble silver salt was added to the dispersion medium at a temperature of 25–35℃ to control the silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring to obtain a primary dispersion of nano-silver.

[0020] After the obtained primary dispersion of silver nanoparticles was stirred at a constant speed for 30–60 min, a small amount of stabilizing auxiliary components were added to the system to form a stable adsorption layer on the surface of the silver nanoparticles, thereby controlling the particle size distribution within the range of 20–80 nm.

[0021] Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain a dispersion of nano-silver.

[0022] To further optimize this technical solution, the addition rate of the reducing agent is controlled at 0.5–2.0 mL / min, which is used to gradually reduce silver ions in the liquid phase to form nanoscale silver particles.

[0023] Meanwhile, the pH of the system was maintained at 6.5–7.5 during the reaction to inhibit the rapid growth and aggregation of silver nanoparticles.

[0024] To further optimize this technical solution, both sodium alginate and calcium chloride are gel-loaded with the nano-silver dispersion in the form of aqueous solutions:

[0025] The dispersion of nano-silver was mixed with sodium alginate aqueous solution at a volume ratio of 1:5–1:20, and stirred slowly at 20–30℃ for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution.

[0026] Subsequently, an aqueous solution of calcium chloride was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking and the formation of a microscopic gel network structure in the system.

[0027] To further optimize this technical solution, the sodium citrate is treated according to the requirements of the sustained-release antibacterial system, including:

[0028] Sodium citrate was added to deionized water and stirred at 20–25°C to dissolve it, controlling the mass concentration to 1–10% (w / v) to obtain a clear and homogeneous aqueous solution. During the dissolution process, the stirring speed was controlled at 200–600 r / min to avoid local high concentrations that could lead to crystal precipitation.

[0029] After dissolution, the sodium citrate solution was subjected to ion environment regulation treatment by adding a buffer aqueous phase to stabilize the pH of the system within the range of 6.8–7.6.

[0030] The sodium citrate solution was then filtered with a pore size controlled at 0.45–1.0 µm to remove any insoluble particles, resulting in a sodium citrate solution suitable for use in sustained-release antibacterial systems.

[0031] To further optimize this technical solution, the sodium citrate solution is pre-equilibrated before use according to the requirements of the sustained-release antibacterial system, namely:

[0032] Sodium citrate solution was contacted with a small amount of silver ion solution for a short time under low concentration conditions, with the contact time controlled between 5 and 20 minutes, so that its ion regulation ability was stabilized.

[0033] To further optimize this technical solution, the sodium hyaluronate used has a weight-average molecular weight of 5 × 10⁻⁶. 4 –8×10 5 Sodium hyaluronate at a concentration of g / mol exists in a low-concentration, uniformly dispersed state in the aqueous phase.

[0034] To further optimize this technical solution, the polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–99% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 g / mol, enabling it to form a continuous molecular chain entanglement structure in the aqueous phase.

[0035] To further optimize this technical solution, the degree of substitution of sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1500 mPa·s in a 2% aqueous solution at 25°C.

[0036] To further optimize this technical solution, the wound dressing includes the following preparation steps:

[0037] S1. Polyvinyl alcohol and sodium carboxymethyl cellulose are added to purified water and heated and stirred until fully dissolved and a homogeneous and stable film-forming matrix solution is formed;

[0038] S2. Add sodium hyaluronate and glycerin to the film-forming matrix solution and disperse them evenly in the system;

[0039] S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a sustained-release network precursor system;

[0040] S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release.

[0041] S5. By adding calcium chloride dropwise, sodium alginate undergoes ionic cross-linking to construct an internal gel network structure;

[0042] S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

[0043] Compared with the prior art, the present invention provides a nano-silver ion sustained-release antibacterial wound dressing, which has the following beneficial effects:

[0044] This nano-silver ion sustained-release antibacterial wound dressing achieves continuous and gradual release of silver ions by constructing a stable polymer film-forming structure and a sustained-release network formed by ion cross-linking within the dressing. This allows the nano-silver to be confined within the gel structure. While ensuring effective antibacterial performance, it significantly reduces the risk of irritation caused by instantaneous release, prolongs the antibacterial effect time, and improves the stability and safety of the dressing during use. It is suitable for applications requiring long-term wound protection and infection control. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the preparation process of a nano-silver ion sustained-release antibacterial wound dressing proposed in this invention. Detailed Implementation

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0049] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0050] A nano-silver ion sustained-release antibacterial wound dressing comprises the following formula in parts by weight:

[0051] Polyvinyl alcohol, 30–80 parts; Polyvinyl alcohol serves as the primary film-forming material in dressings, used to create a continuous, stable, flexible film structure, giving the dressing basic mechanical strength and integrity. Its good water solubility and film-forming properties facilitate the formation of a homogeneous system with other polymeric components, ensuring that the dressing is less prone to breakage or delamination during use.

[0052] Sodium carboxymethyl cellulose, 5–30 parts; Sodium carboxymethyl cellulose is used to improve the absorbency and gelling properties of dressings, allowing them to swell rapidly and remain moist upon contact with wound exudate. Its addition helps enhance the dressing's adherence to the wound surface and reduces interference with newly formed tissue during secondary removal.

[0053] Sodium hyaluronate, 0.2–5 parts; Sodium hyaluronate is used to improve the moisturizing properties of dressings, providing a stable, moist healing environment for wounds. This ingredient reduces moisture loss from the wound surface, improves patient comfort during use, and facilitates gentle contact of the dressing with the skin.

[0054] Glycerin, 2–20 parts; Glycerin acts as a plasticizer and moisturizer, reducing the brittleness of the dressing after film formation, keeping it soft and elastic. Its hygroscopic properties help prevent the dressing from cracking due to moisture loss during storage or use.

[0055] Sodium alginate, 3–25 parts; Sodium alginate is used to construct the gel structure of dressings, forming a gel layer with a certain strength while absorbing exudate. This gel structure can form physical barrier channels inside the dressing, providing a structural basis for the slow release of nano-silver ions.

[0056] Calcium chloride, 0.2–6 parts; calcium chloride is used to form a stable gel network structure through ionic cross-linking with sodium alginate. By adjusting the amount of calcium chloride, the density of the gel can be controlled, thereby regulating the release rate of silver ions in the dressing.

[0057] Nano silver, 0.05–2 parts; Nano silver, as an effective antibacterial ingredient, is used to continuously release silver ions during dressing application, inhibiting or killing common bacteria. Its low-dose dispersion in the dressing system ensures antibacterial efficacy while reducing the risk of skin irritation.

[0058] Sodium citrate, 0.1–3 parts; Sodium citrate is used to regulate the ionic environment and stability of the system, preventing the aggregation of nano-silver during preparation or storage. This component also buffers the release of silver ions, preventing a concentrated release of silver ions in a short period of time.

[0059] Purified water, 200–1200 parts; purified water is used as a solvent and dispersion medium to dissolve or disperse the components to form a uniform and stable dressing preparation system. The amount used can be adjusted according to the dressing forming method.

[0060] The nano-silver was obtained using a combination of wet physical dispersion and chemical reduction to ensure stable particle size and suitability for subsequent sustained-release systems. Specifically, this includes:

[0061] Deionized water was selected as the dispersion medium. Soluble silver salts were added to the dispersion medium at a temperature of 25–35℃ to maintain a silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring at a rate of 0.5–2.0 mL / min to gradually reduce silver ions in the liquid phase, forming nanoscale silver particles, thus obtaining a primary dispersion of silver nanoparticles. Simultaneously, the pH of the system was maintained at 6.5–7.5 during the reaction to inhibit the rapid growth and aggregation of the silver nanoparticles.

[0062] The obtained primary dispersion of silver nanoparticles was stirred at a constant speed for 30–60 min, and then proceeded to a stabilization treatment step. A small amount of stabilizing auxiliary components were added to the system to form a stable adsorption layer on the surface of the silver nanoparticles, thereby controlling the particle size distribution within the range of 20–80 nm. Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain the dispersion of silver nanoparticles.

[0063] To impart restricted release properties to the silver nanoparticles, a gel loading treatment was introduced. Both sodium alginate and calcium chloride were gel-loaded with the silver nanoparticle dispersion in aqueous solution form.

[0064] The dispersion of nano-silver was mixed with sodium alginate aqueous solution at a volume ratio of 1:5–1:20, and stirred slowly at 20–30℃ for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution.

[0065] Subsequently, calcium chloride aqueous solution was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking of the system and the formation of a micro-gel network structure, resulting in a gel-type raw material containing nano-silver. In this raw material, the nano-silver is physically confined within the cross-linked network, providing a stable and controllable sustained-release basis for subsequent dressing applications.

[0066] The sodium citrate is processed according to the requirements for use in sustained-release antibacterial systems, including:

[0067] Sodium citrate was added to deionized water and stirred at 20–25°C to dissolve it, with the mass concentration controlled at 1–10% (w / v) to obtain a clear and homogeneous aqueous solution. During the dissolution process, the stirring speed was controlled at 200–600 r / min to avoid excessive local concentration that could lead to crystallization.

[0068] After dissolution, the sodium citrate solution is subjected to ion environment regulation treatment. By adding a buffer aqueous phase, the pH of the system is stabilized in the range of 6.8–7.6, thereby ensuring that the raw material does not cause a sudden large release of silver ions when it comes into contact with the silver-containing system in the future.

[0069] The sodium citrate solution was then filtered with a pore size controlled between 0.45 and 1.0 µm to remove any insoluble particles, improve the stability and consistency of the system, and obtain a sodium citrate solution suitable for use in sustained-release antibacterial systems.

[0070] To enhance its regulatory effect in sustained-release systems, sodium citrate solution can be pre-equilibrated by contacting it with a small amount of silver ion solution at low concentrations for a short period, controlled within 5–20 minutes, to stabilize its ion regulation capabilities. The sodium citrate solution obtained after this treatment does not exhibit significant precipitation or performance drift under storage conditions, making it suitable as a functional auxiliary material for regulating the ionic environment and release rhythm in sustained-release antibacterial dressings.

[0071] The sodium hyaluronate used has a weight-average molecular weight of 5×10⁻⁶. 4 –8×10 5 Sodium hyaluronate (g / mol) exists in a low-concentration, uniformly dispersed state in the aqueous phase. By controlling the molecular weight and amount of sodium hyaluronate, it is prevented from forming an independent gel phase, but rather embedded in the polymer network as dispersed segments, thereby participating in the regulation of water distribution within the system and avoiding damage to the sustained-release structure of the silver nanoparticles.

[0072] The polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–99% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 By controlling the degree of alcoholysis and molecular weight range of polyvinyl alcohol, g / mol can be used to form a continuous molecular chain entanglement structure in the aqueous phase, thereby constructing a stable continuous polymer phase in the subsequent system. This continuous phase provides the basic support conditions for the confined distribution of silver nanoparticles and the stable existence of the gel network.

[0073] The degree of substitution of the sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1500 mPa·s in a 2% aqueous solution at 25°C. This selection of substitution degree and viscosity range allows the sodium carboxymethyl cellulose to form a swellable but not completely dissolved network structure in the system, thereby forming an interpenetrating polymer system with polyvinyl alcohol, providing additional steric confinement for the silver-containing gel structure.

[0074] After the glycerol is introduced into the aqueous system, it forms hydrogen bonds with the molecular chains of polyvinyl alcohol and sodium carboxymethyl cellulose. This adjusts the spacing between polymer chain segments, thereby reducing the glass transition tendency of the system and ensuring that the gel material maintains a stable and compliant state at room temperature, while not affecting the restricted distribution structure of the silver nanoparticles in the cross-linked network.

[0075] Reference Figure 1 The preparation steps for this wound dressing are as follows:

[0076] S1. Add polyvinyl alcohol and sodium carboxymethyl cellulose to purified water, heat and stir to fully dissolve them and form a homogeneous and stable film-forming matrix solution.

[0077] Specifically, purified water is added to a reaction vessel and heated at 25–40°C while maintaining stirring. Polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) are then added sequentially. The stirring speed is controlled at 300–800 rpm to allow the PVA to gradually swell and completely dissolve, while simultaneously ensuring the CMC is fully dispersed in the aqueous phase, forming a homogeneous polymeric mixture. This construction of a continuous and stable polymer matrix provides a foundational continuous phase for the subsequent formation of the sustained-release structure.

[0078] S2. Add sodium hyaluronate and glycerol to the film-forming matrix solution and disperse them evenly in the system.

[0079] Specifically, in the polymer mixture solution obtained in step S1, the system temperature is maintained within the range of 25–35℃, and sodium hyaluronate and glycerol are added sequentially. During the addition process, the stirring speed is maintained at 200–600 r / min, so that sodium hyaluronate is embedded into the polymer system in a dispersed chain state, while glycerol is evenly distributed in the interstices of the molecular chains, thereby adjusting the water content and flexibility of the system and avoiding embrittlement or structural inhomogeneity problems during subsequent molding.

[0080] S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a slow-release network precursor system.

[0081] Specifically, sodium alginate is added to the system obtained in step S2, and the system temperature is controlled within the range of 20–30℃ and stirred continuously for 30–60 min to allow the sodium alginate to fully expand in the polymer matrix and form a crosslinkable precursor network structure. By controlling the dispersion state of sodium alginate, it is prevented from forming independent gel blocks, but rather uniformly distributed in the continuous phase, providing a spatial basis for subsequent ionic crosslinking.

[0082] S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release.

[0083] Specifically, in the precursor system obtained in step S3, nano-silver is added, and sodium citrate is added simultaneously. The order of addition is to add the nano-silver first, followed by the sodium citrate. During the addition process, the system is slowly stirred (100–400 r / min) to ensure that the nano-silver is uniformly dispersed within the system. Sodium citrate is used to regulate the ionic environment in the system, inhibit the aggregation behavior of the nano-silver in the system, and prevent the instantaneous release of silver ions in subsequent processes.

[0084] S5. Sodium alginate undergoes ionic cross-linking by adding calcium chloride dropwise, thus constructing an internal gel network structure.

[0085] Specifically, in the system obtained in step S4, calcium chloride aqueous solution is added dropwise at a rate controlled at 0.5–3 mL / min. Calcium chloride undergoes ionic cross-linking with sodium alginate, gradually forming a gel network structure within the system. This confines the silver nanoparticles within the cross-linked spatial structure, thereby constructing a slow-release basic structure with restricted silver ion migration. This cross-linking process is carried out at room temperature, and stirring continues for 10–30 min after cross-linking to ensure structural uniformity.

[0086] S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

[0087] Specifically, the homogeneous system obtained in step S5 is spread and shaped, with the spreading thickness controlled within the range of 0.2–3 mm. It is then subjected to natural drying or low-temperature drying at 20–40°C until the moisture content stabilizes. After drying, a nano-silver ion sustained-release antibacterial wound dressing is obtained. Its internal structure retains a sustained-release structure composed of a polymer matrix and an ion-crosslinked gel, enabling the continuous release of antibacterial components.

[0088] Example 1:

[0089] A nano-silver ion sustained-release antibacterial wound dressing includes the following formulation:

[0090] Polyvinyl alcohol, 30 parts;

[0091] Sodium carboxymethyl cellulose, 5 parts;

[0092] Sodium hyaluronate, 0.2 parts;

[0093] Glycerin, 2 parts;

[0094] Sodium alginate, 3 parts;

[0095] Calcium chloride, 0.2 parts;

[0096] Nano silver, 0.05 parts;

[0097] Sodium citrate, 0.1 parts;

[0098] Purified water, 200 portions.

[0099] The nano-silver was obtained using a combination of wet physical dispersion and chemical reduction to ensure stable particle size and suitability for subsequent sustained-release systems. Specifically, this includes:

[0100] Deionized water was selected as the dispersion medium. Soluble silver salt was added to the dispersion medium at 25°C to maintain the silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring at a rate of 0.5–2.0 mL / min to gradually reduce silver ions in the liquid phase, forming nanoscale silver particles, thus obtaining a primary dispersion of nano-silver. Simultaneously, the pH of the system was maintained at 6.5–7.5 during the reaction.

[0101] After stirring the obtained primary dispersion of silver nanoparticles at a constant speed for 30 minutes, a small amount of stabilizing auxiliary components were added to the system to control the particle size distribution within the range of 20–80 nm. Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain the dispersion of silver nanoparticles.

[0102] Sodium alginate and calcium chloride were both gel-loaded with the nano-silver dispersion in aqueous solution:

[0103] The dispersion of nano-silver was mixed with an aqueous solution of sodium alginate and stirred slowly at 20°C for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution.

[0104] Subsequently, an aqueous solution of calcium chloride was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking and the formation of a microscopic gel network structure in the system.

[0105] The sodium citrate is processed according to the requirements for use in sustained-release antibacterial systems, including:

[0106] Sodium citrate was added to deionized water and stirred at 20°C to dissolve it, with the mass concentration controlled at 5% (w / v) to obtain a clear and homogeneous aqueous solution; the stirring speed was controlled at 200 r / min during the dissolution process.

[0107] After dissolution, the sodium citrate solution was subjected to ion environment regulation treatment by adding a buffer aqueous phase to stabilize the pH of the system within the range of 6.8–7.6.

[0108] The sodium citrate solution was then filtered with a pore size controlled at 0.45–1.0 µm to remove any insoluble particles, resulting in a sodium citrate solution suitable for use in sustained-release antibacterial systems.

[0109] The sodium citrate solution was pre-equilibrated by briefly contacting it with a small amount of silver ion solution at low concentrations for 5 minutes to stabilize its ion-regulating ability.

[0110] The sodium hyaluronate used has a weight-average molecular weight of 5×10⁻⁶. 4 –8×10 5 Sodium hyaluronate at a concentration of g / mol exists in a low-concentration, uniformly dispersed state in the aqueous phase.

[0111] The polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–90% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 g / mol.

[0112] The degree of substitution of the sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1000 mPa·s in a 2% aqueous solution at 25°C.

[0113] The preparation steps for this wound dressing are as follows:

[0114] S1. Add polyvinyl alcohol and sodium carboxymethyl cellulose to purified water, heat and stir to fully dissolve them and form a homogeneous and stable film-forming matrix solution.

[0115] Specifically, purified water is added to the reaction vessel and heated at 25°C while maintaining stirring. Then, polyvinyl alcohol and sodium carboxymethyl cellulose are added sequentially. The stirring speed is controlled at 300 r / min to allow the polyvinyl alcohol to gradually swell and completely dissolve, while simultaneously ensuring that the sodium carboxymethyl cellulose is fully dispersed in the aqueous phase, forming a homogeneous polymeric mixture solution.

[0116] S2. Add sodium hyaluronate and glycerol to the film-forming matrix solution and disperse them evenly in the system.

[0117] Specifically, in the polymer mixture solution obtained in step S1, the system temperature is maintained at 25°C, and sodium hyaluronate and glycerol are added sequentially. During the addition process, the stirring speed is maintained at 200 r / min, so that sodium hyaluronate is embedded into the polymer system in a dispersed chain state, while glycerol is uniformly distributed in the interstices of the molecular chains.

[0118] S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a slow-release network precursor system.

[0119] Specifically, sodium alginate is added to the system obtained in step S2, and the system temperature is controlled at 20°C and stirred continuously for 30 minutes to allow sodium alginate to fully expand in the polymer matrix and form a crosslinkable precursor network structure.

[0120] S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release.

[0121] Specifically, in the precursor system obtained in step S3, nano-silver is added, and sodium citrate is added simultaneously. The order of addition is to add nano-silver first and then sodium citrate, and the system is slowly stirred (100 r / min) during the addition process to ensure that the nano-silver is uniformly dispersed in the system.

[0122] S5. Sodium alginate undergoes ionic cross-linking by adding calcium chloride dropwise, thus constructing an internal gel network structure.

[0123] Specifically, in the system obtained in step S4, calcium chloride aqueous solution is added dropwise at a rate controlled at 0.5–3 mL / min. Calcium chloride undergoes ionic cross-linking with sodium alginate, gradually forming a gel network structure within the system. This cross-linking process is carried out at room temperature, and stirring continues for 10 min after cross-linking is complete to ensure structural uniformity.

[0124] S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

[0125] Specifically, the homogeneous system obtained in step S5 is spread and shaped, with the spreading thickness controlled within the range of 0.2–3 mm. It is then subjected to natural drying or low-temperature drying at 20°C until the moisture content stabilizes. After drying, the finished nano-silver ion sustained-release antibacterial wound dressing is obtained.

[0126] Example 2:

[0127] A nano-silver ion sustained-release antibacterial wound dressing includes the following formulation:

[0128] Polyvinyl alcohol, 55 parts;

[0129] Sodium carboxymethyl cellulose, 17.5 parts;

[0130] Sodium hyaluronate, 2.6 parts;

[0131] Glycerin, 11 parts;

[0132] Sodium alginate, 14 parts;

[0133] Calcium chloride, 3.1 parts;

[0134] Nano silver, 1.025 parts;

[0135] Sodium citrate, 1.55 parts;

[0136] Purified water, 700 parts.

[0137] The nano-silver was obtained using a combination of wet physical dispersion and chemical reduction to ensure stable particle size and suitability for subsequent sustained-release systems. Specifically, this includes:

[0138] Deionized water was selected as the dispersion medium. Soluble silver salt was added to the dispersion medium at 25°C to maintain the silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring at a rate of 0.5–2.0 mL / min to gradually reduce silver ions in the liquid phase, forming nanoscale silver particles, thus obtaining a primary dispersion of nano-silver. Simultaneously, the pH of the system was maintained at 6.5–7.5 during the reaction.

[0139] After stirring the obtained primary dispersion of silver nanoparticles at a constant speed for 30 minutes, a small amount of stabilizing auxiliary components were added to the system to control the particle size distribution within the range of 20–80 nm. Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain the dispersion of silver nanoparticles.

[0140] Sodium alginate and calcium chloride were both gel-loaded with the nano-silver dispersion in aqueous solution:

[0141] The dispersion of nano-silver was mixed with an aqueous solution of sodium alginate and stirred slowly at 20°C for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution.

[0142] Subsequently, an aqueous solution of calcium chloride was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking and the formation of a microscopic gel network structure in the system.

[0143] The sodium citrate is processed according to the requirements for use in sustained-release antibacterial systems, including:

[0144] Sodium citrate was added to deionized water and stirred at 20°C to dissolve it, with the mass concentration controlled at 5% (w / v) to obtain a clear and homogeneous aqueous solution; the stirring speed was controlled at 200 r / min during the dissolution process.

[0145] After dissolution, the sodium citrate solution was subjected to ion environment regulation treatment by adding a buffer aqueous phase to stabilize the pH of the system within the range of 6.8–7.6.

[0146] The sodium citrate solution was then filtered with a pore size controlled at 0.45–1.0 µm to remove any insoluble particles, resulting in a sodium citrate solution suitable for use in sustained-release antibacterial systems.

[0147] The sodium citrate solution was pre-equilibrated by briefly contacting it with a small amount of silver ion solution at low concentrations for 5 minutes to stabilize its ion-regulating ability.

[0148] The sodium hyaluronate used has a weight-average molecular weight of 5×10⁻⁶. 4 –8×10 5 Sodium hyaluronate at a concentration of g / mol exists in a low-concentration, uniformly dispersed state in the aqueous phase.

[0149] The polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–90% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 g / mol.

[0150] The degree of substitution of the sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1000 mPa·s in a 2% aqueous solution at 25°C.

[0151] The preparation steps for this wound dressing are as follows:

[0152] S1. Add polyvinyl alcohol and sodium carboxymethyl cellulose to purified water, heat and stir to fully dissolve them and form a homogeneous and stable film-forming matrix solution.

[0153] Specifically, purified water is added to the reaction vessel and heated at 25°C while maintaining stirring. Then, polyvinyl alcohol and sodium carboxymethyl cellulose are added sequentially. The stirring speed is controlled at 300 r / min to allow the polyvinyl alcohol to gradually swell and completely dissolve, while simultaneously ensuring that the sodium carboxymethyl cellulose is fully dispersed in the aqueous phase, forming a homogeneous polymeric mixture solution.

[0154] S2. Add sodium hyaluronate and glycerol to the film-forming matrix solution and disperse them evenly in the system.

[0155] Specifically, in the polymer mixture solution obtained in step S1, the system temperature is maintained at 25°C, and sodium hyaluronate and glycerol are added sequentially. During the addition process, the stirring speed is maintained at 200 r / min, so that sodium hyaluronate is embedded into the polymer system in a dispersed chain state, while glycerol is uniformly distributed in the interstices of the molecular chains.

[0156] S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a slow-release network precursor system.

[0157] Specifically, sodium alginate is added to the system obtained in step S2, and the system temperature is controlled at 20°C and stirred continuously for 30 minutes to allow sodium alginate to fully expand in the polymer matrix and form a crosslinkable precursor network structure.

[0158] S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release.

[0159] Specifically, in the precursor system obtained in step S3, nano-silver is added, and sodium citrate is added simultaneously. The order of addition is to add nano-silver first and then sodium citrate, and the system is slowly stirred (100 r / min) during the addition process to ensure that the nano-silver is uniformly dispersed in the system.

[0160] S5. Sodium alginate undergoes ionic cross-linking by adding calcium chloride dropwise, thus constructing an internal gel network structure.

[0161] Specifically, in the system obtained in step S4, calcium chloride aqueous solution is added dropwise at a rate controlled at 0.5–3 mL / min. Calcium chloride undergoes ionic cross-linking with sodium alginate, gradually forming a gel network structure within the system. This cross-linking process is carried out at room temperature, and stirring continues for 10 min after cross-linking is complete to ensure structural uniformity.

[0162] S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

[0163] Specifically, the homogeneous system obtained in step S5 is spread and shaped, with the spreading thickness controlled within the range of 0.2–3 mm. It is then subjected to natural drying or low-temperature drying at 20°C until the moisture content stabilizes. After drying, the finished nano-silver ion sustained-release antibacterial wound dressing is obtained.

[0164] Example 3:

[0165] A nano-silver ion sustained-release antibacterial wound dressing includes the following formulation:

[0166] Polyvinyl alcohol, 80 parts;

[0167] Sodium carboxymethyl cellulose, 30 parts;

[0168] Sodium hyaluronate, 5 parts;

[0169] Glycerin, 20 parts;

[0170] Sodium alginate, 25 parts;

[0171] Calcium chloride, 6 parts;

[0172] Nano silver, 2 parts;

[0173] Sodium citrate, 3 parts;

[0174] Purified water, 1200 portions.

[0175] The nano-silver was obtained using a combination of wet physical dispersion and chemical reduction to ensure stable particle size and suitability for subsequent sustained-release systems. Specifically, this includes:

[0176] Deionized water was selected as the dispersion medium. Soluble silver salt was added to the dispersion medium at 25°C to maintain the silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring at a rate of 0.5–2.0 mL / min to gradually reduce silver ions in the liquid phase, forming nanoscale silver particles, thus obtaining a primary dispersion of nano-silver. Simultaneously, the pH of the system was maintained at 6.5–7.5 during the reaction.

[0177] After stirring the obtained primary dispersion of silver nanoparticles at a constant speed for 30 minutes, a small amount of stabilizing auxiliary components were added to the system to control the particle size distribution within the range of 20–80 nm. Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain the dispersion of silver nanoparticles.

[0178] Sodium alginate and calcium chloride were both gel-loaded with the nano-silver dispersion in aqueous solution:

[0179] The dispersion of nano-silver was mixed with an aqueous solution of sodium alginate and stirred slowly at 20°C for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution.

[0180] Subsequently, an aqueous solution of calcium chloride was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking and the formation of a microscopic gel network structure in the system.

[0181] The sodium citrate is processed according to the requirements for use in sustained-release antibacterial systems, including:

[0182] Sodium citrate was added to deionized water and stirred at 20°C to dissolve it, with the mass concentration controlled at 5% (w / v) to obtain a clear and homogeneous aqueous solution; the stirring speed was controlled at 200 r / min during the dissolution process.

[0183] After dissolution, the sodium citrate solution was subjected to ion environment regulation treatment by adding a buffer aqueous phase to stabilize the pH of the system within the range of 6.8–7.6.

[0184] The sodium citrate solution was then filtered with a pore size controlled at 0.45–1.0 µm to remove any insoluble particles, resulting in a sodium citrate solution suitable for use in sustained-release antibacterial systems.

[0185] The sodium citrate solution was pre-equilibrated by briefly contacting it with a small amount of silver ion solution at low concentrations for 5 minutes to stabilize its ion-regulating ability.

[0186] The sodium hyaluronate used has a weight-average molecular weight of 5×10⁻⁶. 4 –8×10 5Sodium hyaluronate at a concentration of g / mol exists in a low-concentration, uniformly dispersed state in the aqueous phase.

[0187] The polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–90% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 g / mol.

[0188] The degree of substitution of the sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1000 mPa·s in a 2% aqueous solution at 25°C.

[0189] The preparation steps for this wound dressing are as follows:

[0190] S1. Add polyvinyl alcohol and sodium carboxymethyl cellulose to purified water, heat and stir to fully dissolve them and form a homogeneous and stable film-forming matrix solution.

[0191] Specifically, purified water is added to the reaction vessel and heated at 25°C while maintaining stirring. Then, polyvinyl alcohol and sodium carboxymethyl cellulose are added sequentially. The stirring speed is controlled at 300 r / min to allow the polyvinyl alcohol to gradually swell and completely dissolve, while simultaneously ensuring that the sodium carboxymethyl cellulose is fully dispersed in the aqueous phase, forming a homogeneous polymeric mixture solution.

[0192] S2. Add sodium hyaluronate and glycerol to the film-forming matrix solution and disperse them evenly in the system.

[0193] Specifically, in the polymer mixture solution obtained in step S1, the system temperature is maintained at 25°C, and sodium hyaluronate and glycerol are added sequentially. During the addition process, the stirring speed is maintained at 200 r / min, so that sodium hyaluronate is embedded into the polymer system in a dispersed chain state, while glycerol is uniformly distributed in the interstices of the molecular chains.

[0194] S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a slow-release network precursor system.

[0195] Specifically, sodium alginate is added to the system obtained in step S2, and the system temperature is controlled at 20°C and stirred continuously for 30 minutes to allow sodium alginate to fully expand in the polymer matrix and form a crosslinkable precursor network structure.

[0196] S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release.

[0197] Specifically, in the precursor system obtained in step S3, nano-silver is added, and sodium citrate is added simultaneously. The order of addition is to add nano-silver first and then sodium citrate, and the system is slowly stirred (100 r / min) during the addition process to ensure that the nano-silver is uniformly dispersed in the system.

[0198] S5. Sodium alginate undergoes ionic cross-linking by adding calcium chloride dropwise, thus constructing an internal gel network structure.

[0199] Specifically, in the system obtained in step S4, calcium chloride aqueous solution is added dropwise at a rate controlled at 0.5–3 mL / min. Calcium chloride undergoes ionic cross-linking with sodium alginate, gradually forming a gel network structure within the system. This cross-linking process is carried out at room temperature, and stirring continues for 10 min after cross-linking is complete to ensure structural uniformity.

[0200] S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

[0201] Specifically, the homogeneous system obtained in step S5 is spread and shaped, with the spreading thickness controlled within the range of 0.2–3 mm. It is then subjected to natural drying or low-temperature drying at 20°C until the moisture content stabilizes. After drying, the finished nano-silver ion sustained-release antibacterial wound dressing is obtained.

[0202] Comparative Example 1 (lacking key antibacterial component: nano-silver is 0):

[0203] A nano-silver ion sustained-release antibacterial wound dressing includes the following formulation:

[0204] Polyvinyl alcohol, 55 parts;

[0205] Sodium carboxymethyl cellulose, 17.5 parts;

[0206] Sodium hyaluronate, 2.6 parts;

[0207] Glycerin, 11 parts;

[0208] Sodium alginate, 14 parts;

[0209] Calcium chloride, 3.1 parts;

[0210] Sodium citrate, 1.55 parts;

[0211] Purified water, 700 parts.

[0212] The methods for obtaining each formulation and the preparation process of the wound dressing (the relevant steps for removing nano-silver) are the same as those in Examples 1-3.

[0213] Comparative Example 2 (lacking the key component for sustained-release cross-linking: calcium chloride is 0):

[0214] A nano-silver ion sustained-release antibacterial wound dressing includes the following formulation:

[0215] Polyvinyl alcohol, 55 parts;

[0216] Sodium carboxymethyl cellulose, 17.5 parts;

[0217] Sodium hyaluronate, 2.6 parts;

[0218] Glycerin, 11 parts;

[0219] Sodium alginate, 14 parts;

[0220] Sodium citrate, 1.55 parts;

[0221] Purified water, 700 parts.

[0222] The methods for obtaining each formula and the preparation process of the wound dressing (the relevant steps for removing calcium chloride) are the same as those in Examples 1-3.

[0223] Based on the above embodiments and comparative examples, the prepared nano-silver ion sustained-release antibacterial wound dressing was tested as shown in Table 1 below:

[0224] Table 1

[0225]

[0226] Based on the test content in Table 1, tests were conducted. All three examples (Examples 1, 2, and 3) demonstrated stable and sustained antibacterial performance during dressing use. Specifically, Example 1, with its relatively low levels of nano-silver, sodium alginate, and calcium chloride, exhibited a gentler initiation of antibacterial effect, but with a smooth release process, making it suitable for wound scenarios with high irritation requirements and low exudation. Example 3, with its near-maximum levels of functional components, showed a more significant antibacterial effect, higher absorbency, and stronger structural strength, making it suitable for wound environments with high exudation or infection risk. Example 2, as an intermediate formulation, demonstrated a relatively balanced overall effect in terms of antibacterial performance, silver ion release stability, absorbency, softness, and application comfort.

[0227] In the silver ion release behavior test, none of the three examples showed obvious initial burst release. The release curves showed a gradual increase and then leveling off over time, indicating that the cross-linked structure formed by sodium alginate and calcium chloride can effectively limit the migration rate of nano-silver and achieve continuous release. In the material performance test, the dressings in the examples had an intact overall structure and good flexibility. No obvious cracking or pulverization occurred during spreading and peeling, indicating a good structural synergy among the components.

[0228] Comparative Example 1, which did not contain nano-silver, did not show significant antibacterial activity in antibacterial performance tests, indicating that the dressing matrix itself does not possess effective antibacterial capabilities, and nano-silver is a key technical feature for achieving antibacterial effects. Although this comparative example is similar to the embodiment in terms of absorbency and softness, it is significantly inferior in terms of bacterial control capabilities and cannot meet the application requirements of antibacterial wound dressings.

[0229] Although Comparative Example 2 contained silver nanoparticles, it did not include calcium chloride to form a stable cross-linked structure. During the test, this comparative example showed a rapid silver ion release trend in the initial stage, with the antibacterial effect concentrated in a short period of time, followed by a rapid decline in antibacterial ability. Furthermore, its silver ion release stability was poor, and the system was more prone to fluctuations during storage or use, indicating that without the slow-release network formed by ion cross-linking, it is difficult to achieve continuous and controllable release of silver nanoparticles.

[0230] A comparison of the examples and comparative examples confirms that simply introducing nano-silver is insufficient to achieve a stable and long-lasting antibacterial effect. It is necessary to combine it with a cross-linked sustained-release structure constructed from sodium alginate and calcium chloride to effectively control the silver ion release rate while ensuring antibacterial performance. The synergistic effect of the components in this technical solution in terms of structure and function enables the dressing to possess continuous antibacterial properties, good absorbency, and safe use. This overcomes the shortcomings of existing antibacterial dressings, such as short-lived antibacterial effects or uncontrolled release, and has clear and verifiable technical advantages.

[0231] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A nano-silver ion sustained-release antibacterial wound dressing, characterized in that, The formula includes the following mass fractions: Polyvinyl alcohol, 30–80 parts; Sodium carboxymethyl cellulose, 5–30 parts; Sodium hyaluronate, 0.2–5 parts; Glycerin, 2–20 parts; Sodium alginate, 3–25 parts; Calcium chloride, 0.2–6 parts; Nano silver, 0.05–2 parts; Sodium citrate, 0.1–3 parts; Purified water, 200–1200 parts.

2. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The nano-silver was obtained using a combination of wet physical dispersion and chemical reduction, including: Deionized water was selected as the dispersion medium. Soluble silver salt was added to the dispersion medium at a temperature of 25–35℃ to control the silver ion concentration within the range of 0.01–0.1 mol / L. Subsequently, a reducing agent was introduced under continuous stirring to obtain a primary dispersion of nano-silver. After the obtained primary dispersion of silver nanoparticles was stirred at a constant speed for 30–60 min, a small amount of stabilizing auxiliary components were added to the system to form a stable adsorption layer on the surface of the silver nanoparticles, thereby controlling the particle size distribution within the range of 20–80 nm. Unreacted impurities were removed by low-speed centrifugation or static sedimentation to obtain a dispersion of nano-silver.

3. The nano-silver ion sustained-release antibacterial wound dressing according to claim 2, characterized in that, The addition rate of the reducing agent is controlled at 0.5–2.0 mL / min, which is used to gradually reduce silver ions in the liquid phase to form nanoscale silver particles. Meanwhile, the pH of the system was maintained at 6.5–7.5 during the reaction to inhibit the rapid growth and aggregation of silver nanoparticles.

4. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, Sodium alginate and calcium chloride were both gel-loaded with the nano-silver dispersion in aqueous solution: The dispersion of nano-silver was mixed with sodium alginate aqueous solution at a volume ratio of 1:5–1:20, and stirred slowly at 20–30℃ for 30–90 min to allow the nano-silver to be uniformly embedded in the polymer solution. Subsequently, an aqueous solution of calcium chloride was added dropwise, with the concentration controlled at 0.05–0.3 mol / L, to induce ionic cross-linking and the formation of a microscopic gel network structure in the system.

5. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The sodium citrate is processed according to the requirements for use in sustained-release antibacterial systems, including: Sodium citrate was added to deionized water and stirred at 20–25°C to dissolve it, controlling the mass concentration to 1–10% (w / v) to obtain a clear and homogeneous aqueous solution. During the dissolution process, the stirring speed was controlled at 200–600 r / min to avoid local high concentrations that could lead to crystal precipitation. After dissolution, the sodium citrate solution was subjected to ion environment regulation treatment by adding a buffer aqueous phase to stabilize the pH of the system within the range of 6.8–7.

6. The sodium citrate solution was then filtered with a pore size controlled at 0.45–1.0 µm to remove any insoluble particles, resulting in a sodium citrate solution suitable for use in sustained-release antibacterial systems.

6. The nano-silver ion sustained-release antibacterial wound dressing according to claim 5, characterized in that, The sodium citrate solution is pre-equilibrated before use according to the requirements of a sustained-release antibacterial system, namely: Sodium citrate solution was briefly contacted with a small amount of silver ion solution under low concentration conditions, with the contact time controlled between 5 and 20 minutes, so that its ion regulation ability was stabilized.

7. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The sodium hyaluronate used has a weight-average molecular weight of 5×10⁻⁶. 4 –8×10 5 Sodium hyaluronate at a concentration of g / mol exists in a low-concentration, uniformly dispersed state in the aqueous phase.

8. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The polyvinyl alcohol used is water-soluble polyvinyl alcohol, with its degree of alcoholysis controlled at 85–99% and its number-average molecular weight controlled at 3 × 10⁻⁶. 4 –1.2×10 5 g / mol, enabling it to form a continuous molecular chain entanglement structure in the aqueous phase.

9. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The degree of substitution of the sodium carboxymethyl cellulose is controlled at 0.6–1.2, and the viscosity is controlled at 300–1500 mPa·s in a 2% aqueous solution at 25°C.

10. The nano-silver ion sustained-release antibacterial wound dressing according to claim 1, characterized in that, The preparation steps for this wound dressing are as follows: S1. Polyvinyl alcohol and sodium carboxymethyl cellulose are added to purified water and heated and stirred to fully dissolve them and form a homogeneous and stable film-forming matrix solution; S2. Add sodium hyaluronate and glycerin to the film-forming matrix solution to ensure uniform dispersion within the system; S3. Add sodium alginate to the above system and stir continuously to allow it to fully expand in the polymer matrix and form a sustained-release network precursor system; S4. Add nano-silver and sodium citrate sequentially to the sustained-release network precursor system to ensure uniform dispersion of nano-silver and regulate the ionic environment of the system to avoid instantaneous release. S5. By adding calcium chloride dropwise, sodium alginate undergoes ionic cross-linking to construct an internal gel network structure; S6. Spread and dry the cross-linked system to obtain a finished wound dressing with sustained-release antibacterial effect of nano silver ions.

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