An antibacterial hydrogel dressing and a method of preparing the same

Abstract

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

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of biomedical materials, belongs to the patent classification A61L27 / 52, and particularly relates to an antibacterial hydrogel dressing and a preparation method thereof. BACKGROUND

[0002] In the field of wound care, antibacterial hydrogel dressings have become an important choice for clinical treatment because they can create a moist healing environment and promote tissue repair. Nano-silver has been widely used in antibacterial hydrogel dressings due to its unique small size effect and high specific surface area, which exhibit excellent broad-spectrum antibacterial performance. For example, nano-silver can inhibit the normal metabolism and reproduction of bacteria by combining with biological macromolecules such as proteins and nucleic acids of bacteria, thereby achieving the purpose of sterilization.

[0003] However, the current antibacterial hydrogel dressing using nano-silver as an antibacterial material has obvious defects, especially the problem of lack of sustained-release performance, which needs to be solved urgently. In the prior art, nano-silver is usually simply physically dispersed in the three-dimensional network structure of the hydrogel. This dispersion mode leads to weak interaction between nano-silver and the hydrogel. When the hydrogel dressing contacts wound exudate or is in a humid environment, nano-silver will be rapidly released from the hydrogel, forming a "burst release phenomenon". The burst release phenomenon greatly shortens the effective action time of nano-silver, making it difficult to continuously exert stable antibacterial effect in the entire wound healing cycle. Frequent dressing changes not only cause pain to patients, but also may cause secondary infection of the wound, increasing the workload of medical staff. In addition, the release of high-concentration nano-silver in a short time may also be toxic to normal cells in the human body, affecting the healing process of the wound. When the concentration of silver ions is too high, it will inhibit the proliferation and migration of fibroblasts and hinder the synthesis of collagen, which is not conducive to the growth of granulation tissue. Moreover, the rapid release of nano-silver can easily induce bacterial resistance, reducing its antibacterial efficacy and limiting the application effect and range of the antibacterial hydrogel dressing in clinical practice. SUMMARY

[0004] The application aims to provide an antibacterial hydrogel dressing and a preparation method thereof to solve the technical problem of rapid release of antibacterial silver ions in the background art. The antibacterial hydrogel dressing prepared by the application has good antibacterial ion sustained-release performance and mechanical strength.

[0005] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0006] A preparation method of an antibacterial hydrogel dressing, comprising the following steps:

[0007] S1, preparing nano-silver-hydroxyapatite composite particles;

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

[0009] S3, crosslinking the mixed hydrogel solution under the action of a crosslinking agent to obtain an antibacterial hydrogel dressing.

[0010] In the technical scheme of the present application, nano-silver-hydroxyapatite composite particles are prepared as an antibacterial agent, a nano-silver storage structure is formed with hydroxyapatite as a carrier, and then the nano-silver storage structure is mixed with a hydrogel solution of sodium alginate and carboxymethyl chitosan, and finally crosslinked by a crosslinking agent to form a three-dimensional network. Figure 1 The SEM image of the antibacterial hydrogel dressing prepared in the present application shows that the hydrogel presents a three-dimensional network porous structure. The present application constructs a slow-release system of nano-silver by means of the physical adsorption of hydroxyapatite and the dual action of the crosslinked network of hydrogel, effectively delays the release rate of nano-silver, avoids the burst release phenomenon, realizes the long-acting and stable release of the antibacterial component, and significantly improves the slow-release performance of the antibacterial hydrogel dressing.

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

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

[0013] As a preferred, in the step S3, the crosslinking agent is selected from glutaraldehyde and / or genipin crosslinking agent.

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

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

[0016] A2, adding hydroxyapatite seeds and sodium borohydride reducing agent to the mixed solution, adjusting the pH to 10-11, and heating to react to obtain a reaction liquid;

[0017] A3, filtering, washing and drying the reaction liquid to obtain the nano-silver-hydroxyapatite composite particles.

[0018] In the technical scheme of the present application, the silver nitrate solution and the diammonium hydrogen phosphate solution are mixed first, the preliminary reaction of silver ions and phosphate ions is carried out, so as to provide an ion environment for the in-situ generation of nano-silver on the surface of hydroxyapatite, then the hydroxyapatite crystal seeds are added and heated for reaction, the crystal seeds are used to promote the growth of hydroxyapatite crystals, and under the heating condition, the silver ions are reduced to nano-silver and uniformly loaded on the surface of the hydroxyapatite crystals, so as to form composite particles with a core-shell structure. In the present application, the in-situ synthesis and the crystal seed induction mechanism are used to uniformly embed the nano-silver in the network of hydroxyapatite crystals, so as to form composite particles with the biocompatibility of hydroxyapatite and the broad-spectrum antibacterial property of nano-silver, the three-dimensional crystal network structure of the composite particles can be used as a "slow-release reservoir" of nano-silver, the sustained and slow release of silver ions is realized through ion exchange and diffusion, the burst release problem of traditional nano-silver dressings is effectively solved, and the calcium and phosphorus ions released by the hydroxyapatite can promote the proliferation of osteoblasts and the deposition of collagen in a wound, so as to synergistically improve the antibacterial long-acting property and the healing-promoting performance of the dressing.

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

[0020] Preferably, the nano-silver-hydroxyapatite composite particles are subjected to a modification treatment, which comprises the following steps:

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

[0022] B2, 2-hydroxypropyltrimethylammonium chloride chitosan is grafted to the surface of the epoxy nano-silver-hydroxyapatite composite particles through the ring-opening reaction of the hydroxyl groups on the 2-hydroxypropyltrimethylammonium chloride chitosan and the epoxy groups on the epoxy nano-silver-hydroxyapatite composite particles, so as to obtain quaternary ammonium nano-silver-hydroxyapatite composite particles;

[0023] B3, hyperbranched polyethyleneimine is combined on the surface of the quaternary ammonium nano-silver-hydroxyapatite composite particles.

[0024] In the technical scheme of the present application, as described above, the nanometer silver-hydroxyapatite composite particles are added into the sodium alginate-carboxymethyl chitosan hydrogel matrix, but further problems encountered are that the mechanical strength of the nanometer hydrogel is greatly reduced. It is found by the present application team that this problem is closely related to the uneven dispersion of the nanometer silver-hydroxyapatite in the hydrogel material. The uneven dispersion of the nanometer silver-hydroxyapatite in the hydrogel material is easy to form micron-sized agglomerates, which occupy the gel network space, hinder the mutual entanglement of the carboxymethyl chitosan and the sodium alginate, cause uneven crosslinking density, and locally form a hollow structure, resulting in a decrease in the mechanical properties. In order to further solve this problem, the nanometer silver-hydroxyapatite composite particles are modified in the present application. The epoxy silane coupling agent is first grafted on the surface of the nanometer silver-hydroxyapatite composite particles to load the epoxy functional groups, and then the ring-opening reaction occurs between the epoxy functional groups and the hydroxyl groups on the positively charged 2-hydroxypropyl trimethyl ammonium chloride chitosan, so that the 2-hydroxypropyl trimethyl ammonium chloride chitosan is grafted on the nanometer silver-hydroxyapatite composite particles to make them positively charged. The nanometer silver-hydroxyapatite composite particles are highly dispersed in the hydrogel by using the mutual repulsion between the positively charged nanometer silver-hydroxyapatite composite particles and the mutual attraction between the nanometer silver-hydroxyapatite composite particles and the negatively charged sodium alginate in the hydrogel. In addition, the hyperbranched polyethyleneimine is introduced on the surface thereof on this basis, and the rich amino functional groups form a high-density hydrogen bond network with the hydroxyl groups and the amino groups in the hydrogel, greatly enhancing the interfacial bonding force between the nanometer silver-hydroxyapatite composite particles and the hydrogel matrix. Through the synergistic effect of the above two aspects, the hollow structure in the hydrogel is avoided, and the mechanical strength of the hydrogel is greatly improved.

[0025] Preferably, in step B1, the mass ratio of the nanometer 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 the epoxidized nanometer silver-hydroxyapatite to the 2-hydroxypropyl trimethyl ammonium chloride chitosan is 3:4-6.

[0027] An antibacterial hydrogel dressing is prepared by the method of the above claim.

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

[0029] 1. The hydroxyapatite is used as a carrier to form a nanometer silver storage structure, which combines the dual effects of the crosslinking network of the hydrogel to build a nanometer silver slow-release system, avoid the burst release phenomenon of the antibacterial silver ions released too fast, realize the long-acting and stable release of the antibacterial components, and significantly improve the slow-release performance of the antibacterial hydrogel dressing.

[0030] 2. By in-situ synthesis and seed induction mechanism, the nano-silver is uniformly embedded into the hydroxyapatite crystal network to form composite particles with both the biocompatibility of hydroxyapatite and the broad-spectrum antibacterial property of nano-silver. The calcium and phosphorus ions released by the hydroxyapatite can promote the proliferation of wound osteoblasts and collagen deposition, and synergistically improve the antibacterial long-acting property and healing performance of the dressing.

[0031] 3. The nano-silver-hydroxyapatite composite particles are modified, the 2-hydroxypropyltrimethylammonium chloride chitosan is grafted to make the particles positively charged, the high dispersion of the particles in the hydrogel is realized by using the charge interaction, the hyperbranched polyethyleneimine is introduced to form a high-density hydrogen bond network, the interfacial bonding force between the particles and the hydrogel matrix is enhanced, the hollow structure in the hydrogel is avoided, and the mechanical strength of the hydrogel is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

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

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] Embodiment 1

[0035] Preparation of nano-silver-hydroxyapatite composite particles:

[0036] Step 1: 4.25 g of silver nitrate was weighed and dissolved in 200 mL of deionized water to obtain a silver nitrate solution; 2.64 g of diammonium hydrogen phosphate was weighed and dissolved in 150 mL of deionized water to obtain a diammonium hydrogen phosphate solution; 5.00 g of calcium nitrate was weighed and dissolved in 300 mL of deionized water to obtain a calcium nitrate solution. The silver nitrate solution and the calcium nitrate solution were poured into a four-necked flask, and magnetic stirring (speed 300 rpm) was started. The diammonium hydrogen phosphate solution was slowly added at a rate of 2 mL / min through a constant-pressure dropping funnel, and the reaction temperature was maintained at 40℃ during the addition process. A mixed solution was obtained.

[0037] Step 2: 0.5 g of hydroxyapatite seed and 0.5 g of sodium borohydride were added to the mixed solution, and the pH was adjusted to 10-11 with 25% ammonia water. The reaction system was heated to 55℃, and the temperature was maintained for 8 hours of stirring reaction. During the reaction process, the silver ions were reduced to nano-silver by sodium borohydride and deposited and grew on the surface of the hydroxyapatite seed.

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

[0039] Nano-silver-hydroxyapatite composite particle modification treatment:

[0040] Step 1: Weigh 5.0 g of nano-silver-hydroxyapatite composite particles and add them to 200 mL of anhydrous ethanol. Ultrasonically disperse for 30 minutes (power 300 W). Transfer the dispersion to a four-necked flask, protect with nitrogen, and stir in a 70°C oil bath for 30 minutes. Then slowly add 0.09 g of γ-glycidoxypropyltrimethoxysilane (KH-560). After the addition is complete, continue to react for 12 hours. After the reaction is completed, centrifuge the solution at 8000 rpm for 15 minutes, discard the supernatant, and wash the precipitate with anhydrous ethanol 3 times. Dry at 60°C in a vacuum drying oven for 24 hours to obtain epoxy- modified nano-silver-hydroxyapatite composite particles.

[0041] Step 2: Weigh 3.0 g of epoxy-modified nano-silver-hydroxyapatite composite particles and add them to 400 mL of an ethanol-water solution (ethanol to water volume ratio = 1:1). Ultrasonically disperse for 20 minutes. Transfer the dispersion to a four-necked flask, add 5.5 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC), and add 0.5 g of triethylamine as a catalyst. Adjust the pH to 11 with 1 mol / L sodium hydroxide. Stir in an 80°C oil bath for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo ring-opening reaction with the epoxy groups on the surface of the composite particles. After the reaction is completed, centrifuge the solution at 10000 rpm for 20 minutes, wash the precipitate with anhydrous ethanol 3 times, and dry at 60°C in a vacuum drying oven for 24 hours to obtain quaternary ammonium-modified nano-silver-hydroxyapatite composite particles.

[0042] Step 3: Prepare a 100 mL aqueous solution of 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI), and add 2.0 g of quaternary ammonium-modified nano-silver-hydroxyapatite composite particles. React at 80°C with a stirring speed of 200 rpm for 12 hours. After the reaction is completed, centrifuge the solution, then wash it with deionized water 3 times, and finally freeze-dry for 48 hours to obtain the product.

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

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

[0045] Step 2: Take 2.0 g of modified nano-silver-hydroxyapatite composite particles and add them to 400 mL of hydrogel solution. First, use a high-shear emulsifier to disperse at a speed of 10,000 rpm for 15 minutes, then use an ultrasonic cleaner to ultrasonically treat for 10 minutes (power 200 W) to uniformly disperse the composite particles in the hydrogel solution, obtaining a mixed hydrogel solution.

[0046] Step 3: Pour the mixed hydrogel solution into a 5 cm diameter culture dish. Prepare a crosslinking agent solution: take 0.4 g of genipin and dissolve it in 20 mL of deionized water, stirring until uniform. Slowly add the crosslinking agent solution to the surface of the mixed hydrogel solution in the culture dish, gently shaking the dish while adding to ensure uniform distribution. Let it stand at room temperature for 24 hours to allow the hydrogel to fully solidify. 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 crosslinking agent and impurities. Finally, place the hydrogel in a freeze dryer and freeze dry at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0047] Example 2

[0048] Nano-silver-hydroxyapatite composite particle preparation:

[0049] Step 1: Take 4.25 g of silver nitrate and dissolve it in 200 mL of deionized water to obtain a silver nitrate solution; take 2.64 g of diammonium hydrogen phosphate and dissolve it in 150 mL of deionized water to obtain a diammonium hydrogen phosphate solution; take 5.00 g of calcium nitrate and dissolve it in 300 mL 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 (speed 300 rpm), and slowly add the diammonium hydrogen phosphate solution at a rate of 2 mL / min through a constant pressure dropping funnel, maintaining the reaction temperature at 40°C during the process, obtaining a mixed solution.

[0050] Step 2: Add 0.5 g of hydroxyapatite seed crystals and 0.5 g of sodium borohydride to the mixed solution, adjust the pH to 10-11 with 25% ammonia water, and heat the reaction system to 55°C, maintaining this temperature for 6 hours of stirring reaction. During the reaction, silver ions are reduced to nano-silver by sodium borohydride and deposited and grown on the surface of the hydroxyapatite seed crystals.

[0051] Step 3: After the reaction is complete, cool the reaction liquid to room temperature, collect the solid product by vacuum filtration, and wash the solid with deionized water three times to remove unreacted ions and impurities. Finally, dry the product in a 60°C vacuum drying oven for 12 hours to obtain nano-silver-hydroxyapatite composite particles.

[0052] Nano-silver-hydroxyapatite composite particle modification treatment:

[0053] Step 1: 5.0 g of nano-silver-hydroxyapatite composite particles were weighed and added to 200 mL of anhydrous ethanol, and ultrasonically dispersed for 30 minutes (power 300 W). The dispersion was transferred to a four-necked flask, protected by nitrogen, and stirred in an oil bath at 70°C for 30 minutes of activation. Then 0.06 g of γ-glycidoxypropyltrimethoxysilane (KH-560) was slowly added dropwise, and after the addition was completed, the reaction was continued for 12 hours. After the reaction was completed, the solution was centrifuged at 8000 rpm for 15 minutes, the supernatant was discarded, the precipitate was washed with anhydrous ethanol three times, and vacuum dried at 60°C for 24 hours to obtain epoxidized nano-silver-hydroxyapatite composite particles.

[0054] Step 2: 3.0 g of epoxidized nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of an ethanol-water solution (ethanol to water volume ratio = 1:1) and ultrasonically dispersed for 20 minutes. The dispersion was transferred to a four-necked flask, 4.5 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added, and 0.5 g of triethylamine was added as a catalyst, and the pH was adjusted to 11 with 1 mol / L sodium hydroxide. Stirring at 80°C oil bath for 24 hours allows the hydroxyl groups on the HTCC molecules to undergo ring-opening reaction with the epoxy groups on the surface of the composite particles. After the reaction was completed, the solution was centrifuged at 10000 rpm for 20 minutes, the precipitate was washed with anhydrous ethanol three times, and vacuum dried at 60°C for 24 hours to obtain quaternized nano-silver-hydroxyapatite composite particles.

[0055] Step 3: Prepare a 100 mL aqueous solution of 1.0% (w / v) hyperbranched polyethyleneimine (HBPEI), and add 2.0 g of quaternized nano-silver-hydroxyapatite composite particles, and react at 80°C with a stirring speed of 200 rpm for 12 hours. After the reaction was completed, the solution was centrifuged, then washed with deionized water three times, and finally freeze-dried for 48 hours to obtain the product.

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

[0057] Step 1: 7.0 g of sodium alginate and 1.5 g of carboxymethyl chitosan were weighed and added to 500 mL of deionized water, and stirred at 300 rpm in a 50°C water bath for 2 hours until completely dissolved to form a uniform transparent mixed solution. The pH of the solution was adjusted to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0058] Step 2: Take 2.0 g of modified nano-silver-hydroxyapatite composite particles and add them to 400 mL of hydrogel solution. First, use a high-shear emulsifier to disperse at a speed of 10,000 rpm for 15 minutes, then use an ultrasonic cleaner to ultrasonically treat for 10 minutes (power 200 W) to uniformly disperse the composite particles in the hydrogel solution, obtaining a mixed hydrogel solution.

[0059] Step 3: Pour the mixed hydrogel solution into a culture dish with a diameter of 5 cm. Prepare a crosslinking agent solution: take 0.4 g of genipin and dissolve it in 20 mL of deionized water, stirring until uniform. Slowly add the crosslinking agent solution to the surface of the mixed hydrogel solution in the culture dish, gently shaking the dish while adding to ensure uniform distribution. Let it stand at room temperature for 24 hours to allow the hydrogel to fully solidify. 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 crosslinking agent and impurities. Finally, place the hydrogel in a freeze dryer and freeze dry at -50°C and 0.1 Pa for 24 hours to obtain an antibacterial hydrogel dressing.

[0060] Example 3

[0061] Nano-silver-hydroxyapatite composite particle preparation:

[0062] Step 1: Take 4.25 g of silver nitrate and dissolve it in 200 mL of deionized water to obtain a silver nitrate solution; take 2.64 g of diammonium hydrogen phosphate and dissolve it in 150 mL of deionized water to obtain a diammonium hydrogen phosphate solution; take 5.00 g of calcium nitrate and dissolve it in 300 mL 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 (speed 300 rpm), and slowly add the diammonium hydrogen phosphate solution at a rate of 2 mL / min through a constant-pressure dropping funnel, maintaining the reaction temperature at 40°C during the process, obtaining a mixed solution.

[0063] Step 2: Add 0.5 g of hydroxyapatite seed crystals and 0.5 g of sodium borohydride to the mixed solution, adjust the pH to 10-11 with 25% ammonia water, and heat the reaction system to 55°C, maintaining this temperature for 7 hours of stirring reaction. During the reaction, silver ions are reduced to nano-silver by sodium borohydride and deposited and grown on the surface of the hydroxyapatite seed crystals.

[0064] Step 3: After the reaction is complete, cool the reaction liquid to room temperature, collect the solid product by vacuum filtration, and wash the solid with deionized water three times to remove unreacted ions and impurities. Finally, dry the product in a vacuum drying oven at 60°C for 12 hours to obtain nano-silver-hydroxyapatite composite particles.

[0065] Nano-silver-hydroxyapatite composite particle modification:

[0066] Step 1: 5.0 g of nano-silver-hydroxyapatite composite particles were weighed and added to 200 mL of anhydrous ethanol, and ultrasonic dispersion was performed for 30 minutes (power 300 W). The dispersion was transferred to a four-necked flask, and nitrogen was introduced for protection. The solution was stirred in an oil bath at 70°C for 30 minutes to activate. Then, 0.07 g of γ-glycidoxypropyltrimethoxysilane (KH-560) was slowly added dropwise, and after the addition was completed, the reaction was continued for 12 hours. After the reaction was completed, the solution was centrifuged at 8000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed with anhydrous ethanol three times, and vacuum dried at 60°C for 24 hours to obtain epoxy-modified nano-silver-hydroxyapatite composite particles.

[0067] Step 2: 3.0 g of epoxy-modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of an ethanol-water solution (ethanol to water volume ratio = 1:1), and ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, 5.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added, and 0.5 g of triethylamine was added as a catalyst. The pH was adjusted to 11 with 1 mol / L sodium hydroxide. The solution was stirred in an oil bath at 80°C for 24 hours to allow the hydroxyl groups on the HTCC molecules to undergo ring-opening reaction with the epoxy groups on the surface of the composite particles. After the reaction was completed, the solution was centrifuged at 10000 rpm for 20 minutes, and the precipitate was washed with anhydrous ethanol three times. The solution was vacuum dried at 60°C for 24 hours to obtain quaternary ammonium-modified nano-silver-hydroxyapatite composite particles.

[0068] Step 3: A 1.0% (w / v) aqueous solution of hyperbranched polyethyleneimine (HBPEI) was prepared, and 2.0 g of quaternary ammonium-modified nano-silver-hydroxyapatite composite particles were added. The solution was stirred at 80°C and a stirring speed of 200 rpm for 12 hours. After the reaction was completed, the solution was centrifuged, then washed with deionized water three times, and finally freeze-dried for 48 hours to obtain the product.

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

[0070] Step 1: 7.0 g of sodium alginate and 2.0 g of carboxymethyl chitosan were weighed and added to 500 mL of deionized water. The solution was stirred in a water bath at 50°C at a speed of 300 rpm for 2 hours until it was completely dissolved to form a uniform transparent mixed solution. The pH of the solution was adjusted to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0071] Step 2: 2.0 g of modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of the hydrogel solution. A high-shear emulsifier was used to disperse the solution at a speed of 10000 rpm for 15 minutes, and then an ultrasonic cleaner was used to ultrasonically treat the solution for 10 minutes (power 200 W) to uniformly disperse the composite particles in the hydrogel solution, thereby obtaining a mixed hydrogel solution.

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

[0073] Example 4

[0074] Preparation of silver nanoparticle-hydroxyapatite composite particles:

[0075] Step 1: Weigh 4.25 g of silver nitrate and dissolve in 200 mL of deionized water to obtain a silver nitrate solution; weigh 2.64 g of diammonium hydrogen phosphate and dissolve in 150 mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00 g of calcium nitrate and dissolve in 300 mL 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 (speed 300 rpm), slowly add the diammonium hydrogen phosphate solution at a rate of 2 mL / min through a constant pressure dropping funnel, and maintain the reaction temperature at 40°C during the addition process to obtain a mixed solution.

[0076] Step 2: Add 0.5 g of hydroxyapatite seed crystals and 0.5 g of sodium borohydride to the mixed solution, adjust the pH to 10-11 with 25% ammonia water, and heat the reaction system to 60°C, maintaining the temperature for 9 hours of stirring reaction. During the reaction, silver ions are reduced to silver nanoparticles by sodium borohydride and deposited and grown on the surface of the hydroxyapatite seed crystals.

[0077] Step 3: After the reaction is complete, cool the reaction solution to room temperature, and collect the solid product by vacuum filtration. Wash the solid with deionized water 3 times to remove unreacted ions and impurities. Finally, dry the product in a vacuum drying oven at 60°C for 12 hours to obtain silver nanoparticle-hydroxyapatite composite particles.

[0078] Modification of silver nanoparticle-hydroxyapatite composite particles:

[0079] Step 1: 5.0 g of nano-silver-hydroxyapatite composite particles were weighed and added to 200 mL of anhydrous ethanol, and ultrasonic dispersion was performed for 30 minutes (power 300 W). The dispersion was transferred to a four-necked flask, and nitrogen was introduced for protection. The solution was stirred in an oil bath at 70°C for 30 minutes to activate. Then, 0.1 g of γ-glycidoxypropyltrimethoxysilane (KH-560) was slowly added dropwise. After the addition was completed, the reaction was continued for 12 hours. After the reaction was completed, the solution was centrifuged at 8000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed with anhydrous ethanol three times, and vacuum drying was performed at 60°C for 24 hours to obtain epoxy-modified nano-silver-hydroxyapatite composite particles.

[0080] Step 2: 3.0 g of epoxy-modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of an ethanol-water solution (ethanol to water volume ratio = 1:1), and ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, 6.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added, and 0.5 g of triethylamine was added as a catalyst. The pH was adjusted to 11 with 1 mol / L sodium hydroxide. The solution was stirred in an oil bath at 80°C for 24 hours to allow the ring-opening reaction of the hydroxyl groups on the HTCC molecules and the epoxy groups on the surface of the composite particles. After the reaction was completed, the solution was centrifuged at 10000 rpm for 20 minutes, and the precipitate was washed with anhydrous ethanol three times. Vacuum drying was performed at 60°C for 24 hours to obtain quaternary ammonium-modified nano-silver-hydroxyapatite composite particles.

[0081] Step 3: A 1.0% (w / v) aqueous solution of hyperbranched polyethyleneimine (HBPEI) was prepared in 100 mL, and 2.0 g of quaternary ammonium-modified nano-silver-hydroxyapatite composite particles were added. The solution was stirred at 80°C and 200 rpm for 12 hours. After the reaction was completed, the solution was centrifuged, then washed with deionized water three times, and finally freeze-dried for 48 hours to obtain the product.

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

[0083] Step 1: 7.0 g of sodium alginate and 3.0 g of carboxymethyl chitosan were weighed and added to 500 mL of deionized water. The solution was stirred in a 50°C water bath at a speed of 300 rpm for 2 hours until it was completely dissolved to form a uniform transparent mixed solution. The pH of the solution was adjusted to 6.0 with 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0084] Step 2: 2.0 g of modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of the hydrogel solution. A high-shear emulsifier was used to disperse the solution at a speed of 10000 rpm for 15 minutes, and then an ultrasonic cleaner was used to ultrasonically treat the solution for 10 minutes (power 200 W) to uniformly disperse the composite particles in the hydrogel solution, obtaining a mixed hydrogel solution.

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

[0086] Example 5

[0087] Preparation of silver nanoparticle-hydroxyapatite composite particles:

[0088] Step 1: Weigh 4.25 g of silver nitrate and dissolve in 200 mL of deionized water to obtain a silver nitrate solution; weigh 2.64 g of diammonium hydrogen phosphate and dissolve in 150 mL of deionized water to obtain a diammonium hydrogen phosphate solution; weigh 5.00 g of calcium nitrate and dissolve in 300 mL 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 (speed 300 rpm), slowly add the diammonium hydrogen phosphate solution at a rate of 2 mL / min through a constant pressure dropping funnel, and maintain the reaction temperature at 40°C during the addition process to obtain a mixed solution.

[0089] Step 2: Add 0.5 g of hydroxyapatite seed crystals and 0.5 g of sodium borohydride to the mixed solution, adjust the pH to 10-11 with 25% ammonia water, and heat the reaction system to 50°C, maintaining this temperature for 5 hours of stirring reaction. During the reaction, silver ions are reduced to silver nanoparticles by sodium borohydride and deposited and grown on the surface of the hydroxyapatite seed crystals.

[0090] Step 3: After the reaction is complete, cool the reaction solution to room temperature, and collect the solid product by vacuum filtration. Wash the solid with deionized water 3 times to remove unreacted ions and impurities. Finally, dry the product in a vacuum drying oven at 60°C for 12 hours to obtain silver nanoparticle-hydroxyapatite composite particles.

[0091] Modification of silver nanoparticle-hydroxyapatite composite particles:

[0092] Step 1: 5.0 g of nano-silver-hydroxyapatite composite particles were weighed and added to 200 mL of anhydrous ethanol, and ultrasonic dispersion was performed for 30 minutes (power 300 W). The dispersion was transferred to a four-necked flask, and nitrogen was introduced for protection. The solution was stirred in an oil bath at 70°C for 30 minutes to activate. Then, 0.05 g of γ-glycidoxypropyltrimethoxysilane (KH-560) was slowly added dropwise. After the addition was completed, the reaction was continued for 12 hours. After the reaction was completed, the solution was centrifuged at 8000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed with anhydrous ethanol three times, and vacuum drying was performed at 60°C for 24 hours to obtain epoxy-modified nano-silver-hydroxyapatite composite particles.

[0093] Step 2: 3.0 g of epoxy-modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of an ethanol-water solution (volume ratio of ethanol to water = 1:1), and ultrasonic dispersion was performed for 20 minutes. The dispersion was transferred to a four-necked flask, 4.0 g of 2-hydroxypropyltrimethylammonium chloride chitosan (HTCC) was added, and 0.5 g of triethylamine was added as a catalyst. The pH was adjusted to 11 using 1 mol / L sodium hydroxide. The solution was stirred in an oil bath at 80°C for 24 hours to allow the ring-opening reaction of the hydroxyl groups on the HTCC molecules and the epoxy groups on the surface of the composite particles. After the reaction was completed, the solution was centrifuged at 10000 rpm for 20 minutes, and the precipitate was washed with anhydrous ethanol three times. Vacuum drying was performed at 60°C for 24 hours to obtain quaternary ammonium-modified nano-silver-hydroxyapatite composite particles.

[0094] Step 3: A 1.0% (w / v) aqueous solution of hyperbranched polyethyleneimine (HBPEI) was prepared in 100 mL, and 2.0 g of quaternary ammonium-modified nano-silver-hydroxyapatite composite particles were added. The solution was stirred at 80°C and a stirring speed of 200 rpm for 12 hours. After the reaction was completed, the solution was centrifuged, then washed three times with deionized water, and finally freeze-dried for 48 hours to obtain the product.

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

[0096] Step 1: 7.0 g of sodium alginate and 1.0 g of carboxymethyl chitosan were weighed and added to 500 mL of deionized water. The solution was stirred in a water bath at 50°C at a speed of 300 rpm for 2 hours until it was completely dissolved to form a uniform transparent mixed solution. The pH of the solution was adjusted to 6.0 using 1 mol / L hydrochloric acid to obtain a hydrogel solution.

[0097] Step 2: 2.0 g of modified nano-silver-hydroxyapatite composite particles were weighed and added to 400 mL of the hydrogel solution. A high-shear emulsifier was used to disperse the solution at a speed of 10000 rpm for 15 minutes, and then an ultrasonic cleaner was used for ultrasonic treatment at a power of 200 W for 10 minutes to uniformly disperse the composite particles in the hydrogel solution, obtaining a mixed hydrogel solution.

[0098] Step 3: Pour the mixed hydrogel solution into a 5cm diameter petri dish. Prepare the cross-linking agent solution: Weigh 0.4g genipin and dissolve it in 20mL of deionized water, stirring until homogeneous. Slowly add the cross-linking agent solution dropwise to the surface of the mixed hydrogel solution in the petri dish, gently shaking the dish while adding to ensure even distribution of the cross-linking agent. Allow the hydrogel to stand at room temperature for 24 hours to allow it to fully solidify. After cross-linking, remove the hydrogel from the petri dish and immerse it in PBS buffer (pH=7.4) for 24 hours to remove unreacted cross-linking agent and impurities. Finally, place the hydrogel in a freeze dryer and freeze-dry it at -50℃ and 0.1Pa for 24 hours to obtain the antibacterial hydrogel dressing.

[0099] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that in the preparation process of the antibacterial hydrogel dressing, the modified nano-silver-hydroxyapatite composite particles were replaced with an equal mass of nano-silver.

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

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

[0102] Performance testing:

[0103] 1. Sustained-release performance test: The release behavior under physiological conditions was simulated using the dialysis bag method. 1g of hydrogel dressing was cut into small pieces, placed in a dialysis bag with a molecular weight cutoff of 3500 Da, sealed, and then placed in 50mL of PBS buffer (pH 7.4, 0.1M). The bag was shaken at 100rpm in a 37℃ constant-temperature shaking incubator. 1mL of the release solution was collected after 24h and 7d, filtered through a 0.22μm filter, and the silver ion concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS). Simultaneously, 1mL of freshly warmed PBS buffer (preheated to 37℃) was added to the system. The cumulative release rate was calculated as follows: Cumulative release rate (%) = (Total silver ions released at each time point / Total silver ion load in the dressing) × 100%. Three parallel samples were used for each test, and the average value was taken. The test results are shown in Table 1.

[0104] 2. Mechanical Property Testing: The mechanical properties of the gel material were tested using a universal testing machine. After freeze-drying the hydrogel dressing, it was cut into specimens with gauge lengths of 5 mm × 2 mm × 1 mm using a dumbbell-shaped die. Before testing, the specimens were soaked in PBS buffer for 24 hours until swelling equilibrium was reached. After blotting the surface moisture with filter paper, they were fixed in the testing machine fixtures with a fixture spacing of 10 mm. The test was conducted 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, approximately 1×10⁻⁶). 8 (CFU / mL), diluted to 1×10 with 0.85% physiological saline. 6 CFU / mL. Spread 100 μL of bacterial suspension evenly onto an LB agar plate. Place a 6 mm diameter hydrogel disc in the center of the plate. Incubate at 37°C for 24 h. Measure the diameter of the inhibition zone using calipers (accurate to 0.1 mm). Perform three parallel tests per group and calculate the average value. The results are shown in Table 2.

[0108] Table 2:

[0109]

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

Claims

1. A method of preparing an antibacterial hydrogel dressing, characterized by, The method comprises the following steps: S1, preparing nano-silver-hydroxyapatite composite particles: A1, mixing silver nitrate solution, diammonium hydrogen phosphate solution and calcium nitrate solution to obtain a mixed solution; A2, adding hydroxyapatite crystal seeds and sodium borohydride reducing agent to the mixed solution, adjusting pH to 10-11, heating and reacting to obtain a reaction solution; A3, filtering, washing and drying the reaction solution to obtain the nano-silver-hydroxyapatite composite particles; The nano-silver-hydroxyapatite composite particles are modified by the following steps: B1, grafting an epoxy silane coupling agent onto the surface of the nano-silver-hydroxyapatite composite particles to obtain epoxy nano-silver-hydroxyapatite composite particles; B2, grafting 2-hydroxypropyltrimethylammonium chloride chitosan onto the surface of the epoxy nano-silver-hydroxyapatite composite particles by ring-opening reaction of the hydroxyl groups on the 2-hydroxypropyltrimethylammonium chloride chitosan and the epoxy groups on the epoxy nano-silver-hydroxyapatite composite particles to obtain quaternary ammonium nano-silver-hydroxyapatite composite particles; B3, combining hyperbranched polyethyleneimine on the surface of the quaternary ammonium nano-silver-hydroxyapatite composite particles to obtain the modified nano-silver-hydroxyapatite composite particles; S2, mixing the modified nano-silver-hydroxyapatite composite particles with a hydrogel solution to obtain a mixed hydrogel solution; the hydrogel solution is a mixed solution of sodium alginate and carboxymethyl chitosan; S3, crosslinking the mixed hydrogel solution under the action of a crosslinking agent to obtain an antibacterial hydrogel dressing.

2. A method of preparing an antimicrobial hydrogel dressing according to claim 1, wherein, The mass ratio of the sodium alginate to the carboxymethyl chitosan is 7:1-3.

3. A method of preparing an antimicrobial hydrogel dressing according to claim 1, wherein, In step S3, the crosslinking agent is selected from glutaraldehyde and / or genipin crosslinking agent.

4. The method of claim 1, wherein the antimicrobial hydrogel dressing is prepared by the steps of: In A2, the heating reaction temperature is 50-60℃, and the reaction time is 5-9h.

5. The method of claim 1, wherein the antimicrobial hydrogel dressing is prepared by the steps of: 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.

6. The method of claim 1, wherein the antimicrobial hydrogel dressing is prepared by the steps of: In step B2, the mass ratio of the epoxy nano-silver-hydroxyapatite to the 2-hydroxypropyltrimethylammonium chloride chitosan is 3:4-6.

7. An antimicrobial hydrogel dressing, characterized in that, The method is prepared by the method of any one of claims 1-6.

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