Antibacterial hydrogel dressing and preparation method thereof

Abstract

The invention discloses an antibacterial hydrogel dressing and a preparation method thereof, relates to the technical field of biomedical materials, and belongs to the patent classification number A61L27 / 52. The preparation method of the antibacterial hydrogel dressing comprises the following steps: firstly, preparing nano-silver-hydroxyapatite composite particles; secondly, the nano silver-hydroxyapatite composite particles are mixed with a hydrogel solution, and a mixed hydrogel solution is obtained; finally, the mixed hydrogel solution is subjected to a cross-linking reaction under the action of a cross-linking agent, and the antibacterial hydrogel dressing is obtained. The antibacterial hydrogel dressing prepared by the invention has good antibacterial ion slow release performance and mechanical strength.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, belongs to patent classification number A61L27 / 52, and specifically relates to an antibacterial hydrogel dressing and a preparation method thereof. Background Art

[0002] In the field of wound care, antimicrobial hydrogel dressings have become an important clinical treatment option due to their ability to create a moist healing environment and promote tissue repair. Nanosilver, with its unique small size effect and high specific surface area, exhibits excellent broad-spectrum antimicrobial properties, significantly inhibiting Gram-positive and Gram-negative bacteria, as well as fungi, and is widely used in antimicrobial hydrogel dressings. For example, nanosilver can release silver ions to bind to bacterial biomacromolecules such as proteins and nucleic acids, disrupting their normal metabolism and reproduction, thereby achieving a sterilizing effect.

[0003] However, current antimicrobial hydrogel dressings using nanosilver as their antimicrobial material have significant drawbacks, particularly the lack of sustained-release properties, which urgently need to be addressed. In existing technologies, nanosilver is typically simply physically dispersed within the hydrogel's three-dimensional network structure. This dispersion method results in a weak interaction between the nanosilver and the hydrogel. When the hydrogel dressing comes into contact with wound exudate or is exposed to a moist environment, the nanosilver is rapidly released from the hydrogel, resulting in a "burst release phenomenon." This burst release phenomenon significantly shortens the effective duration of the nanosilver's action, making it difficult to maintain a stable antimicrobial effect throughout the wound healing cycle. Frequent dressing changes are not only painful for patients but can also cause secondary wound infections and increase the workload of medical staff. Furthermore, the high concentration of nanosilver released over a short period of time can be toxic to normal human cells, impacting the wound healing process. For example, excessively high silver ion concentrations can inhibit the proliferation and migration of fibroblasts, hinder collagen synthesis, and hinder the growth of granulation tissue. Moreover, the rapid release of nanosilver can easily induce bacterial resistance, reduce its antibacterial efficacy, and limit the clinical application effect and scope of antibacterial hydrogel dressings. Summary of the Invention

[0004] The present invention aims to provide an antibacterial hydrogel dressing and a method for preparing the same, in order to solve the technical problem of excessively rapid release of antibacterial silver ions raised in the above-mentioned background art. The antibacterial hydrogel dressing prepared by the present invention has good sustained release of antibacterial ions and mechanical strength.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0007] S1. Preparation of nano-silver-hydroxyapatite composite particles;

[0008] S2, mixing the nanosilver-hydroxyapatite composite particles with the hydrogel solution to obtain a mixed hydrogel solution;

[0009] S3. Cross-linking the mixed hydrogel solution under the action of a cross-linking agent to obtain an antibacterial hydrogel dressing.

[0010] In the technical solution of the present invention, nanosilver-hydroxyapatite composite particles are first prepared as an antibacterial agent, hydroxyapatite is used as a carrier to form a nanosilver storage structure, and then it is mixed with a hydrogel solution of sodium alginate and carboxymethyl chitosan, and finally cross-linked with a cross-linking agent to form a three-dimensional network. Figure 1 This is a SEM image of the antibacterial hydrogel dressing prepared in the present invention. The electron micrograph shows that the hydrogel exhibits a three-dimensional network porous structure. Leveraging the dual effects of hydroxyapatite's physical adsorption and the hydrogel's cross-linked network, the present invention constructs a sustained-release system for nanosilver, effectively slowing its release rate and preventing sudden release. This allows for long-term, stable release of the antibacterial component, significantly enhancing the sustained-release performance of the antibacterial hydrogel dressing.

[0011] Preferably, in step S2, the hydrogel solution is a mixed solution of sodium alginate and carboxymethyl chitosan.

[0012] Preferably, the mass ratio of sodium alginate to carboxymethyl chitosan is 7:1-3.

[0013] Preferably, in step S3, the cross-linking agent is glutaraldehyde and / or genipin cross-linking agent.

[0014] Preferably, the preparation method of the nano silver-hydroxyapatite composite particles comprises the following steps:

[0015] A1. Mixing silver nitrate solution, diammonium hydrogen phosphate solution and calcium nitrate solution to obtain a mixed solution;

[0016] A2. Add hydroxyapatite seed crystals and sodium borohydride reducing agent to the mixed solution, adjust the pH to 10-11, and heat to react to obtain a reaction solution;

[0017] A3. The reaction solution is filtered, washed and dried to obtain the product.

[0018] In the technical solution of the present invention, a silver nitrate solution is first mixed with a diammonium hydrogen phosphate solution. Through the initial reaction of silver ions and phosphate ions, an ionic environment is provided for the subsequent in-situ generation of nanosilver on the surface of hydroxyapatite. Then, hydroxyapatite seeds are added and heated to react. The induction effect of the seeds is used to promote the growth of hydroxyapatite crystals. At the same time, under heating conditions, the silver ions are reduced to nanosilver and uniformly loaded on the surface of the hydroxyapatite crystals to form composite particles with a core-shell structure. The present invention uses in-situ synthesis and seed induction mechanisms to uniformly embed nanosilver into the hydroxyapatite crystal network. The composite particles formed have both the biocompatibility of hydroxyapatite and the broad-spectrum antibacterial properties of nanosilver. Its three-dimensional crystal network structure can serve as a "sustained release reservoir" for nanosilver, achieving a sustained and slow release of silver ions through ion exchange and diffusion, effectively solving the problem of sudden release of traditional nanosilver dressings. At the same time, the calcium and phosphate ions released by hydroxyapatite can promote the proliferation of osteoblasts and collagen deposition in the wound, synergistically improving the long-term antibacterial and healing properties of the dressing.

[0019] Preferably, in the A2, the heating reaction temperature is 50-60° C., and the reaction time is 5-9 h.

[0020] Preferably, the nano-silver-hydroxyapatite composite particles are modified, comprising the following steps:

[0021] B1, grafting an epoxy silane coupling agent onto the surface of the nano-silver-hydroxyapatite composite particles to obtain epoxidized nano-silver-hydroxyapatite composite particles;

[0022] B2, allowing the hydroxyl groups on the 2-hydroxypropyltrimethylammonium chloride chitosan to undergo a ring-opening reaction with the epoxy groups on the epoxidized nano-silver-hydroxyapatite composite particles, thereby grafting the 2-hydroxypropyltrimethylammonium chloride chitosan onto the surface of the epoxidized nano-silver-hydroxyapatite composite particles to obtain quaternized nano-silver-hydroxyapatite composite particles;

[0023] B3. Combining hyperbranched polyethyleneimine on the surface of quaternized nano silver-hydroxyapatite composite particles to obtain.

[0024] In the technical solution of the present invention, as mentioned above, nano silver-hydroxyapatite composite particles are added to the sodium alginate-carboxymethyl chitosan hydrogel matrix, but a further problem encountered is that the mechanical strength of the nano hydrogel decreases significantly. After research by the present invention team, it was found that this problem is closely related to the uneven dispersion of nano silver-hydroxyapatite in the hydrogel material. Nano silver-hydroxyapatite is unevenly dispersed in the hydrogel material and easily forms micron-sized aggregates. The aggregates occupy the gel network space, hindering the mutual entanglement of carboxymethyl chitosan and sodium alginate, resulting in uneven cross-linking density, local accumulation to form a void structure, and causing its mechanical properties to decrease. To further solve this problem, the present invention modifies nano silver-hydroxyapatite composite particles. An epoxy silane coupling agent is first grafted onto the surface of the nano silver-hydroxyapatite composite particles to load epoxy functional groups. The epoxy functional groups thereon are then utilized to generate a ring-opening reaction with the hydroxyl groups on the positively charged 2-hydroxypropyltrimethylammonium chloride chitosan. Thus, the 2-hydroxypropyltrimethylammonium chloride chitosan is grafted onto the nano silver-hydroxyapatite composite particles to make them positively charged. The positive charges between the nano silver-hydroxyapatite composite particles are mutually repelled, and the attraction between the nano silver-hydroxyapatite composite particles and the negatively charged sodium alginate in the hydrogel is utilized to achieve high dispersion in the hydrogel. In addition, on this basis, hyperbranched polyethyleneimine is introduced onto the surface of the nano silver-hydroxyapatite composite particles. The abundant amino functional groups thereof form a high-density hydrogen bond network with the hydroxyl groups and amino groups in the hydrogel, significantly enhancing the interfacial bonding force between the nano silver-hydroxyapatite composite particles and the hydrogel matrix. Through the synergistic effect of the above two aspects, the formation of a hollow structure inside the hydrogel is avoided, and the mechanical strength of the hydrogel is significantly improved.

[0025] Preferably, in step B1, the mass ratio of the nano-silver-hydroxyapatite composite particles to the epoxy silane coupling agent is 5:0.05-0.1.

[0026] Preferably, in step B2, the mass ratio of epoxidized nano-silver-hydroxyapatite to 2-hydroxypropyltrimethylammonium chloride chitosan is 3:4-6.

[0027] An antibacterial hydrogel dressing is prepared by the method described in the above claims.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Using hydroxyapatite as a carrier to form a nanosilver storage structure, combined with the dual effects of the hydrogel cross-linking network, a nanosilver sustained-release system is constructed to avoid the sudden release of antibacterial silver ions that is too fast, achieve long-term and stable release of antibacterial ingredients, and significantly improve the sustained-release performance of the antibacterial hydrogel dressing.

[0030] 2. Through in-situ synthesis and seed-induced mechanisms, silver nanoparticles are uniformly embedded within the hydroxyapatite crystal network, resulting in composite particles that combine the biocompatibility of hydroxyapatite with the broad-spectrum antimicrobial properties of silver nanoparticles. The calcium and phosphate ions released by hydroxyapatite promote osteoblast proliferation and collagen deposition in wounds, synergistically enhancing the long-term antimicrobial and healing properties of the dressing.

[0031] 3. The nanosilver-hydroxyapatite composite particles were modified by grafting 2-hydroxypropyltrimethylammonium chloride chitosan to make them positively charged, and the charge interaction was used to achieve high dispersion of the particles in the hydrogel; hyperbranched polyethyleneimine was introduced to form a high-density hydrogen bond network, which enhanced the interfacial bonding between the particles and the hydrogel matrix, avoided the formation of void structures inside the hydrogel, and significantly improved the mechanical strength of the hydrogel. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the SEM image of the antibacterial hydrogel dressing prepared in the present invention. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] Example 1

[0035] Preparation of nanosilver-hydroxyapatite composite particles:

[0036] Step 1: Weigh 4.25g of silver nitrate and dissolve it in 200mL of deionized water to obtain a silver nitrate solution; weigh 2.64g of diammonium hydrogen phosphate and dissolve it in 150mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00g of calcium nitrate and dissolve it in 300mL of deionized water to obtain a calcium nitrate solution. Pour the silver nitrate solution and calcium nitrate solution into a four-necked flask, start magnetic stirring (300rpm), and slowly add the diammonium hydrogen phosphate solution dropwise at a rate of 2mL / min through a constant pressure dropping funnel. Maintain the reaction temperature at 40°C during the addition to obtain a mixed solution.

[0037] Step 2: Add 0.5g of hydroxyapatite seed crystals and 0.5g of sodium borohydride to the mixed solution. Adjust the pH to 10-11 with 25% ammonia water. Heat the reaction system to 55°C and maintain this temperature with stirring for 8 hours. During the reaction, silver ions are reduced by sodium borohydride to nanosilver, which then deposits and grows on the surface of the hydroxyapatite seed crystals.

[0038] Step 3: After the reaction is complete, the reaction solution is cooled to room temperature and the solid product is collected by vacuum filtration. The solid product is washed three times with deionized water to remove unreacted ions and impurities. Finally, the product is dried in a vacuum drying oven at 60°C for 12 hours to obtain nanosilver-hydroxyapatite composite particles.

[0039] Modification of nanosilver-hydroxyapatite composite particles:

[0040] Step 1: Weigh 5.0 g of nanosilver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonic dispersion is performed at 300 W for 30 minutes. The dispersion is transferred to a four-necked flask, purged with nitrogen, and activated in a 70°C oil bath with stirring for 30 minutes. Then, 0.09 g of γ-glycidoxypropyltrimethoxysilane (KH-560) is slowly added dropwise. After the addition is complete, the reaction is continued for 12 hours. After the reaction is complete, the solution is centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, and the precipitate is washed three times with anhydrous ethanol and dried in a vacuum at 60°C for 24 hours to obtain epoxidized nanosilver-hydroxyapatite composite particles.

[0041] Step 2: Weigh 3.0 g of epoxidized nanosilver-hydroxyapatite composite particles and add them to 400 mL of ethanol-water solution (ethanol:water volume ratio = 1:1). Ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, and 5.5 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added. 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. The mixture was stirred in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo a ring-opening reaction with the epoxy groups on the composite particle surface. After the reaction, the solution was centrifuged at 10,000 rpm for 20 minutes. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain quaternized nanosilver-hydroxyapatite composite particles.

[0042] Step 3: Prepare 100 mL of a 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI) aqueous solution, add 2.0 g of quaternized nanosilver-hydroxyapatite composite particles, and react at 80°C and 200 rpm for 12 hours. After the reaction, centrifuge the solution, wash three times with deionized water, and freeze-dry for 48 hours.

[0043] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0044] Step 1: Weigh 7.0g of sodium alginate and 2.5g of carboxymethyl chitosan into 500mL of deionized water. Place in a 50°C water bath and stir at 300rpm for 2 hours until completely dissolved to form a homogeneous, transparent mixed solution. Adjust the pH of the solution to 6.0 with 1mol / L hydrochloric acid to obtain a hydrogel solution.

[0045] Step 2: Weigh 2.0 g of modified nanosilver-hydroxyapatite composite particles and add them to 400 mL of the hydrogel solution. Disperse the particles using a high-shear emulsifier at 10,000 rpm for 15 minutes. Then, ultrasonicate the mixture for 10 minutes (200 W) in an ultrasonic cleaner to evenly disperse the composite particles in the hydrogel solution, yielding a mixed hydrogel solution.

[0046] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare the crosslinker solution: Weigh 0.4 g of genipin, dissolve it in 20 mL of deionized water, and stir evenly. Slowly add the crosslinker solution dropwise to the surface of the mixed hydrogel solution in the culture dish, gently shaking the culture dish while adding to ensure even distribution of the crosslinker. Allow the crosslinking to stand at room temperature for 24 hours to fully solidify the hydrogel. After crosslinking is complete, remove the hydrogel from the culture dish and soak it in PBS buffer (pH = 7.4) for 24 hours to remove unreacted crosslinker and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0047] Example 2

[0048] Preparation of nanosilver-hydroxyapatite composite particles:

[0049] Step 1: Weigh 4.25g of silver nitrate and dissolve it in 200mL of deionized water to obtain a silver nitrate solution; weigh 2.64g of diammonium hydrogen phosphate and dissolve it in 150mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00g of calcium nitrate and dissolve it in 300mL of deionized water to obtain a calcium nitrate solution. Pour the silver nitrate solution and calcium nitrate solution into a four-necked flask, start magnetic stirring (300rpm), and slowly add the diammonium hydrogen phosphate solution dropwise at a rate of 2mL / min through a constant pressure dropping funnel. Maintain the reaction temperature at 40°C during the addition to obtain a mixed solution.

[0050] Step 2: Add 0.5g of hydroxyapatite seed crystals and 0.5g of sodium borohydride to the mixed solution. Adjust the pH to 10-11 with 25% ammonia water. Heat the reaction system to 55°C and maintain this temperature with stirring for 6 hours. During the reaction, silver ions are reduced by sodium borohydride to nanosilver, which then deposits and grows on the surface of the hydroxyapatite seed crystals.

[0051] Step 3: After the reaction is complete, the reaction solution is cooled to room temperature and the solid product is collected by vacuum filtration. The solid product is washed three times with deionized water to remove unreacted ions and impurities. Finally, the product is dried in a vacuum drying oven at 60°C for 12 hours to obtain nanosilver-hydroxyapatite composite particles.

[0052] Modification of nanosilver-hydroxyapatite composite particles:

[0053] Step 1: Weigh 5.0 g of nanosilver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonic dispersion is performed at 300 W for 30 minutes. The dispersion is transferred to a four-necked flask, purged with nitrogen, and activated in a 70°C oil bath with stirring for 30 minutes. Then, 0.06 g of γ-glycidoxypropyltrimethoxysilane (KH-560) is slowly added dropwise. After the addition is complete, the reaction is continued for 12 hours. After the reaction is complete, the solution is centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, and the precipitate is washed three times with anhydrous ethanol and dried in a vacuum at 60°C for 24 hours to obtain epoxidized nanosilver-hydroxyapatite composite particles.

[0054] Step 2: Weigh 3.0 g of epoxidized nanosilver-hydroxyapatite composite particles and add them to 400 mL of ethanol-water solution (ethanol:water volume ratio = 1:1). Ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, and 4.5 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added. 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. The mixture was stirred in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo a ring-opening reaction with the epoxy groups on the composite particle surface. After the reaction, the solution was centrifuged at 10,000 rpm for 20 minutes. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain quaternized nanosilver-hydroxyapatite composite particles.

[0055] Step 3: Prepare 100 mL of a 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI) aqueous solution, add 2.0 g of quaternized nanosilver-hydroxyapatite composite particles, and react at 80°C and 200 rpm for 12 hours. After the reaction, centrifuge the solution, wash three times with deionized water, and freeze-dry for 48 hours.

[0056] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0057] Step 1: Weigh 7.0g of sodium alginate and 1.5g of carboxymethyl chitosan into 500mL of deionized water. Place in a 50°C water bath and stir at 300rpm for 2 hours until completely dissolved, forming a homogeneous, transparent mixed solution. Adjust the pH of the solution to 6.0 with 1mol / L hydrochloric acid to obtain a hydrogel solution.

[0058] Step 2: Weigh 2.0 g of modified nanosilver-hydroxyapatite composite particles and add them to 400 mL of the hydrogel solution. Disperse the particles using a high-shear emulsifier at 10,000 rpm for 15 minutes. Then, ultrasonicate the mixture for 10 minutes (200 W) in an ultrasonic cleaner to evenly disperse the composite particles in the hydrogel solution, yielding a mixed hydrogel solution.

[0059] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare the crosslinker solution: Weigh 0.4 g of genipin, dissolve it in 20 mL of deionized water, and stir evenly. Slowly add the crosslinker solution dropwise to the surface of the mixed hydrogel solution in the culture dish, gently shaking the culture dish while adding to ensure even distribution of the crosslinker. Allow the crosslinking to stand at room temperature for 24 hours to fully solidify the hydrogel. After crosslinking is complete, remove the hydrogel from the culture dish and soak it in PBS buffer (pH = 7.4) for 24 hours to remove unreacted crosslinker and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0060] Example 3

[0061] Preparation of nanosilver-hydroxyapatite composite particles:

[0062] Step 1: Weigh 4.25g of silver nitrate and dissolve it in 200mL of deionized water to obtain a silver nitrate solution; weigh 2.64g of diammonium hydrogen phosphate and dissolve it in 150mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00g of calcium nitrate and dissolve it in 300mL of deionized water to obtain a calcium nitrate solution. Pour the silver nitrate solution and calcium nitrate solution into a four-necked flask, start magnetic stirring (300rpm), and slowly add the diammonium hydrogen phosphate solution dropwise at a rate of 2mL / min through a constant pressure dropping funnel. Maintain the reaction temperature at 40°C during the addition to obtain a mixed solution.

[0063] Step 2: Add 0.5g of hydroxyapatite seed crystals and 0.5g of sodium borohydride to the mixed solution. Adjust the pH to 10-11 with 25% ammonia water. Heat the reaction system to 55°C and maintain this temperature with stirring for 7 hours. During the reaction, silver ions are reduced by sodium borohydride to nanosilver, which then deposits and grows on the surface of the hydroxyapatite seed crystals.

[0064] Step 3: After the reaction is complete, the reaction solution is cooled to room temperature and the solid product is collected by vacuum filtration. The solid product is washed three times with deionized water to remove unreacted ions and impurities. Finally, the product is dried in a vacuum drying oven at 60°C for 12 hours to obtain nanosilver-hydroxyapatite composite particles.

[0065] Modification of nanosilver-hydroxyapatite composite particles:

[0066] Step 1: Weigh 5.0 g of nanosilver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonic dispersion is performed at 300 W for 30 minutes. The dispersion is transferred to a four-necked flask, purged with nitrogen, and activated in a 70°C oil bath with stirring for 30 minutes. Then, 0.07 g of γ-glycidoxypropyltrimethoxysilane (KH-560) is slowly added dropwise. After the addition is complete, the reaction is continued for 12 hours. After the reaction is complete, the solution is centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, and the precipitate is washed three times with anhydrous ethanol and dried in a vacuum at 60°C for 24 hours to obtain epoxidized nanosilver-hydroxyapatite composite particles.

[0067] Step 2: Weigh 3.0 g of epoxidized nanosilver-hydroxyapatite composite particles and add them to 400 mL of ethanol-water solution (ethanol:water volume ratio = 1:1). Ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, and 5.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added. 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. The mixture was stirred in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo a ring-opening reaction with the epoxy groups on the composite particle surface. After the reaction, the solution was centrifuged at 10,000 rpm for 20 minutes. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain quaternized nanosilver-hydroxyapatite composite particles.

[0068] Step 3: Prepare 100 mL of a 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI) aqueous solution, add 2.0 g of quaternized nanosilver-hydroxyapatite composite particles, and react at 80°C and 200 rpm for 12 hours. After the reaction, centrifuge the solution, wash three times with deionized water, and freeze-dry for 48 hours.

[0069] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0070] Step 1: Weigh 7.0 g of sodium alginate and 2.0 g of carboxymethyl chitosan into 500 mL of deionized water. Place in a 50°C water bath and stir at 300 rpm for 2 hours until completely dissolved, forming a homogeneous, transparent mixed solution. Adjust the pH of the solution to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0071] Step 2: Weigh 2.0 g of modified nanosilver-hydroxyapatite composite particles and add them to 400 mL of the hydrogel solution. Disperse the particles using a high-shear emulsifier at 10,000 rpm for 15 minutes. Then, ultrasonicate the mixture for 10 minutes (200 W) in an ultrasonic cleaner to evenly disperse the composite particles in the hydrogel solution, yielding a mixed hydrogel solution.

[0072] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare the crosslinker solution: Weigh 0.4 g of genipin, dissolve it in 20 mL of deionized water, and stir evenly. Slowly add the crosslinker solution dropwise to the surface of the mixed hydrogel solution in the culture dish, gently shaking the culture dish while adding to ensure even distribution of the crosslinker. Allow the crosslinking to stand at room temperature for 24 hours to fully solidify the hydrogel. After crosslinking is complete, remove the hydrogel from the culture dish and soak it in PBS buffer (pH = 7.4) for 24 hours to remove unreacted crosslinker and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0073] Example 4

[0074] Preparation of nanosilver-hydroxyapatite composite particles:

[0075] Step 1: Weigh 4.25g of silver nitrate and dissolve it in 200mL of deionized water to obtain a silver nitrate solution; weigh 2.64g of diammonium hydrogen phosphate and dissolve it in 150mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00g of calcium nitrate and dissolve it in 300mL of deionized water to obtain a calcium nitrate solution. Pour the silver nitrate solution and calcium nitrate solution into a four-necked flask, start magnetic stirring (300rpm), and slowly add the diammonium hydrogen phosphate solution dropwise at a rate of 2mL / min through a constant pressure dropping funnel. Maintain the reaction temperature at 40°C during the addition to obtain a mixed solution.

[0076] Step 2: Add 0.5g of hydroxyapatite seed crystals and 0.5g of sodium borohydride to the mixed solution. Adjust the pH to 10-11 with 25% ammonia water. Raise the temperature of the reaction system to 60°C and maintain the temperature with stirring for 9 hours. During the reaction, the silver ions are reduced by the sodium borohydride to nanosilver, which then deposits and grows on the surface of the hydroxyapatite seed crystals.

[0077] Step 3: After the reaction is complete, the reaction solution is cooled to room temperature and the solid product is collected by vacuum filtration. The solid product is washed three times with deionized water to remove unreacted ions and impurities. Finally, the product is dried in a vacuum drying oven at 60°C for 12 hours to obtain nanosilver-hydroxyapatite composite particles.

[0078] Modification of nanosilver-hydroxyapatite composite particles:

[0079] Step 1: Weigh 5.0 g of nanosilver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonic dispersion is performed at 300 W for 30 minutes. The dispersion is transferred to a four-necked flask, purged with nitrogen, and activated in a 70°C oil bath with stirring for 30 minutes. Then, 0.1 g of γ-glycidoxypropyltrimethoxysilane (KH-560) is slowly added dropwise. After the addition is complete, the reaction is continued for 12 hours. After the reaction is complete, the solution is centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, and the precipitate is washed three times with anhydrous ethanol and dried in a vacuum at 60°C for 24 hours to obtain epoxidized nanosilver-hydroxyapatite composite particles.

[0080] Step 2: Weigh 3.0 g of epoxidized nanosilver-hydroxyapatite composite particles and add them to 400 mL of ethanol-water solution (ethanol:water volume ratio = 1:1). Ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, and 6.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added. 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. The mixture was stirred in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo a ring-opening reaction with the epoxy groups on the composite particle surface. After the reaction, the solution was centrifuged at 10,000 rpm for 20 minutes. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain quaternized nanosilver-hydroxyapatite composite particles.

[0081] Step 3: Prepare 100 mL of a 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI) aqueous solution, add 2.0 g of quaternized nanosilver-hydroxyapatite composite particles, and react at 80°C and 200 rpm for 12 hours. After the reaction, centrifuge the solution, wash three times with deionized water, and freeze-dry for 48 hours.

[0082] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0083] Step 1: Weigh 7.0 g of sodium alginate and 3.0 g of carboxymethyl chitosan into 500 mL of deionized water. Place in a 50°C water bath and stir at 300 rpm for 2 hours until completely dissolved, forming a homogeneous, transparent mixed solution. Adjust the pH of the solution to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0084] Step 2: Weigh 2.0 g of modified nanosilver-hydroxyapatite composite particles and add them to 400 mL of the hydrogel solution. Disperse the particles using a high-shear emulsifier at 10,000 rpm for 15 minutes. Then, ultrasonicate the mixture for 10 minutes (200 W) in an ultrasonic cleaner to evenly disperse the composite particles in the hydrogel solution, yielding a mixed hydrogel solution.

[0085] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare the crosslinker solution: Weigh 0.4 g of genipin, dissolve it in 20 mL of deionized water, and stir evenly. Slowly add the crosslinker solution dropwise to the surface of the mixed hydrogel solution in the culture dish, gently shaking the culture dish while adding to ensure even distribution of the crosslinker. Allow the crosslinking to stand at room temperature for 24 hours to fully solidify the hydrogel. After crosslinking is complete, remove the hydrogel from the culture dish and soak it in PBS buffer (pH = 7.4) for 24 hours to remove unreacted crosslinker and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0086] Example 5

[0087] Preparation of nanosilver-hydroxyapatite composite particles:

[0088] Step 1: Weigh 4.25g of silver nitrate and dissolve it in 200mL of deionized water to obtain a silver nitrate solution; weigh 2.64g of diammonium hydrogen phosphate and dissolve it in 150mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00g of calcium nitrate and dissolve it in 300mL of deionized water to obtain a calcium nitrate solution. Pour the silver nitrate solution and calcium nitrate solution into a four-necked flask, start magnetic stirring (300rpm), and slowly add the diammonium hydrogen phosphate solution dropwise at a rate of 2mL / min through a constant pressure dropping funnel. Maintain the reaction temperature at 40°C during the addition to obtain a mixed solution.

[0089] Step 2: Add 0.5g of hydroxyapatite seed crystals and 0.5g of sodium borohydride to the mixed solution. Adjust the pH to 10-11 with 25% ammonia water. Heat the reaction system to 50°C and maintain this temperature with stirring for 5 hours. During the reaction, silver ions are reduced by sodium borohydride to nanosilver, which then deposits and grows on the surface of the hydroxyapatite seed crystals.

[0090] Step 3: After the reaction is complete, the reaction solution is cooled to room temperature and the solid product is collected by vacuum filtration. The solid product is washed three times with deionized water to remove unreacted ions and impurities. Finally, the product is dried in a vacuum drying oven at 60°C for 12 hours to obtain nanosilver-hydroxyapatite composite particles.

[0091] Modification of nanosilver-hydroxyapatite composite particles:

[0092] Step 1: Weigh 5.0 g of nanosilver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonic dispersion is performed at 300 W for 30 minutes. The dispersion is transferred to a four-necked flask, purged with nitrogen, and activated in a 70°C oil bath with stirring for 30 minutes. Then, 0.05 g of γ-glycidoxypropyltrimethoxysilane (KH-560) is slowly added dropwise. After the addition is complete, the reaction is continued for 12 hours. After the reaction is complete, the solution is centrifuged at 8000 rpm for 15 minutes, the supernatant is discarded, and the precipitate is washed three times with anhydrous ethanol and dried in a vacuum at 60°C for 24 hours to obtain epoxidized nanosilver-hydroxyapatite composite particles.

[0093] Step 2: Weigh 3.0 g of epoxidized nanosilver-hydroxyapatite composite particles and add them to 400 mL of ethanol-water solution (ethanol:water volume ratio = 1:1). Ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, and 4.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added. 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. The mixture was stirred in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo a ring-opening reaction with the epoxy groups on the composite particle surface. After the reaction, the solution was centrifuged at 10,000 rpm for 20 minutes. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain quaternized nanosilver-hydroxyapatite composite particles.

[0094] Step 3: Prepare 100 mL of a 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI) aqueous solution, add 2.0 g of quaternized nanosilver-hydroxyapatite composite particles, and react at 80°C and 200 rpm for 12 hours. After the reaction, centrifuge the solution, wash three times with deionized water, and freeze-dry for 48 hours.

[0095] A method for preparing an antibacterial hydrogel dressing comprises the following steps:

[0096] Step 1: Weigh 7.0 g of sodium alginate and 1.0 g of carboxymethyl chitosan into 500 mL of deionized water. Place in a 50°C water bath and stir at 300 rpm for 2 hours until completely dissolved, forming a homogeneous, transparent mixed solution. Adjust the pH of the solution to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0097] Step 2: Weigh 2.0 g of modified nanosilver-hydroxyapatite composite particles and add them to 400 mL of the hydrogel solution. Disperse the particles using a high-shear emulsifier at 10,000 rpm for 15 minutes. Then, ultrasonicate the mixture for 10 minutes (200 W) in an ultrasonic cleaner to evenly disperse the composite particles in the hydrogel solution, yielding a mixed hydrogel solution.

[0098] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare the crosslinker solution: Weigh 0.4 g of genipin, dissolve it in 20 mL of deionized water, and stir evenly. Slowly add the crosslinker solution dropwise to the surface of the mixed hydrogel solution in the culture dish, gently shaking the culture dish while adding to ensure even distribution of the crosslinker. Allow the crosslinking to stand at room temperature for 24 hours to fully solidify the hydrogel. After crosslinking is complete, remove the hydrogel from the culture dish and soak it in PBS buffer (pH = 7.4) for 24 hours to remove unreacted crosslinker and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0099] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that during the preparation of the antibacterial hydrogel dressing, the modified nanosilver-hydroxyapatite composite particles are replaced with nanosilver of equal mass.

[0100] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that during the preparation of the antibacterial hydrogel dressing, the modified nano-silver-hydroxyapatite composite particles are replaced with unmodified nano-silver-hydroxyapatite composite particles of equal mass.

[0101] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that step 3 is omitted during the modification process of the nano-silver-hydroxyapatite composite particles, that is, the outer surface of the nano-silver-hydroxyapatite is not coated with hyperbranched polyethyleneimine (HBPEI).

[0102] Performance testing:

[0103] 1. Sustained-release performance testing: A dialysis bag method was used to simulate release behavior in a physiological environment. 1 g of hydrogel dressing was cut into pieces, placed in a dialysis bag with a molecular weight cutoff of 3500 Da, sealed, and placed in 50 mL of PBS buffer (pH 7.4, 0.1 M). The bag was shaken at 100 rpm in a 37°C constant-temperature shaking incubator. 1 mL of the release solution was removed after 24 hours and 7 days, filtered through a 0.22 μm filter, and the silver ion concentration was determined using an inductively coupled plasma-mass spectrometer. Simultaneously, 1 mL of fresh PBS buffer preheated to 37°C was added to the system. The cumulative release rate was calculated as follows: Cumulative release rate (%) = (Total amount of silver ions released at each time point / Total silver ion loading in the dressing) × 100%. Three replicates were set up for each test, and the average value was calculated. The test results are shown in Table 1.

[0104] 2. Mechanical Properties: The mechanical properties of the gel material were tested using a universal materials testing machine. After freeze-drying the hydrogel dressing, a dumbbell-shaped die was used to cut the specimens into sections measuring 5 mm × 2 mm × 1 mm. Prior to testing, the specimens were immersed in PBS buffer for 24 hours until swelling equilibrium was achieved. After absorbing surface moisture with filter paper, the specimens were secured to the testing machine fixtures with a 10 mm spacing between the fixtures. Testing was performed at a tensile rate of 5 mm / min, and the tensile strength of the specimens was calculated based on the maximum breaking load. The test results are shown in Table 1.

[0105] Table 1:

[0106]

[0107] 3. Antibacterial performance test: Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) were inoculated into LB broth and cultured at 37°C with shaking until the logarithmic growth phase (OD600 = 0.5, about 1 × 10 8 CFU / mL), diluted with 0.85% saline to 1 × 10 6 CFU / mL. Spread 100 μL of bacterial solution evenly on an LB agar plate. Place a 6 mm diameter hydrogel disc in the center of the plate. Incubate at 37°C for 24 hours. Measure the diameter of the inhibition zone (accurate to 0.1 mm) using a vernier caliper. Test three replicates per group and calculate the average value. See Table 2 for test results.

[0108] Table 2:

[0109]

[0110] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an antibacterial hydrogel dressing, characterized in that: The following steps are involved: S1. Preparation of nano-silver-hydroxyapatite composite particles; S2, mixing the nanosilver-hydroxyapatite composite particles with the hydrogel solution to obtain a mixed hydrogel solution; S3. Cross-linking the mixed hydrogel solution under the action of a cross-linking agent to obtain an antibacterial hydrogel dressing.

2. The method for preparing an antibacterial hydrogel dressing according to claim 1, characterized in that: In step S2, the hydrogel solution is a mixed solution of sodium alginate and carboxymethyl chitosan.

3. The method for preparing an antibacterial hydrogel dressing according to claim 2, characterized in that: The mass ratio of the sodium alginate to carboxymethyl chitosan is 7:1-3.

4. The method for preparing an antibacterial hydrogel dressing according to claim 1, characterized in that: In step S3, the cross-linking agent is glutaraldehyde and / or genipin cross-linking agent.

5. The method for preparing an antibacterial hydrogel dressing according to claim 1, characterized in that: The preparation method of the nano silver-hydroxyapatite composite particles comprises the following steps: A1. Mixing a silver nitrate solution, a diammonium hydrogen phosphate solution, and a calcium nitrate solution to obtain a mixed solution; A2. Add hydroxyapatite seed crystals and sodium borohydride reducing agent to the mixed solution, adjust the pH to 10-11, and heat to react to obtain a reaction solution; A3. The reaction solution is filtered, washed and dried to obtain the product.

6. The method for preparing an antibacterial hydrogel dressing according to claim 5, characterized in that: In the above-mentioned A2, the heating reaction temperature is 50-60° C., and the reaction time is 5-9 h.

7. The method for preparing an antibacterial hydrogel dressing according to claim 5, characterized in that: The nano silver-hydroxyapatite composite particles are modified, comprising the following steps: B1, grafting an epoxy silane coupling agent onto the surface of the nano-silver-hydroxyapatite composite particles to obtain epoxidized nano-silver-hydroxyapatite composite particles; B2, allowing the hydroxyl groups on the 2-hydroxypropyltrimethylammonium chloride chitosan to undergo a ring-opening reaction with the epoxy groups on the epoxidized nano-silver-hydroxyapatite composite particles, thereby grafting the 2-hydroxypropyltrimethylammonium chloride chitosan onto the surface of the epoxidized nano-silver-hydroxyapatite composite particles to obtain quaternized nano-silver-hydroxyapatite composite particles; B3. Combining hyperbranched polyethyleneimine on the surface of quaternized nano silver-hydroxyapatite composite particles to obtain.

8. The method for preparing an antibacterial hydrogel dressing according to claim 7, characterized in that: In the step B1, the mass ratio of the nano silver-hydroxyapatite composite particles to the epoxy silane coupling agent is 5:0.05-0.

1.

9. The method for preparing an antibacterial hydrogel dressing according to claim 7, characterized in that: In the step B2, the mass ratio of epoxidized nano-silver-hydroxyapatite to 2-hydroxypropyltrimethylammonium chloride chitosan is 3:4-6.

10. An antibacterial hydrogel dressing, characterized in that: The product is prepared by the method described in any one of claims 1 to 9 above.

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