Silver-containing polyurethane foam dressing and preparation method thereof

Abstract

The invention discloses a silver-containing polyurethane foam dressing and a preparation method thereof, and relates to the technical field of dressings. The silver-containing polyurethane foam dressing is prepared by mixing a component A and a component B in a mass ratio of 1: (0.6-2), the component A is a waterborne polyurethane prepolymer; the component B comprises the following raw material components in parts by weight: 70-90 parts of deionized water, 5-10 parts of a surfactant, 5-10 parts of a hydrophilic agent, 2-5 parts of a thickening agent and 4-8 parts of a silver-containing antibacterial agent; wherein 4-8 parts of modified chitosan and 1-2 parts of plant polyphenol are further added into the component B. Finally, the silver-containing polyurethane foam dressing with excellent bacteriostasis and healing promotion performance is comprehensively prepared, and the silver-containing antibacterial agent contained in the silver-containing polyurethane foam dressing further has a slow-release effect, so that the silver-containing polyurethane foam dressing better meets the clinical wound nursing requirement.

Description

Technical Field

[0001] This invention relates to the field of dressing technology, specifically to a silver-containing polyurethane foam dressing and its preparation method. Background Technology

[0002] Silver-containing antibacterial foams are widely used in medical wound dressings due to their excellent antibacterial properties. However, existing technologies still have significant shortcomings: First, in terms of antibacterial performance, existing silver-containing foam dressings generally suffer from short-lasting antibacterial effects and uncontrollable release behavior. For example, although the immersion method for loading soluble silver salts (as described in CN104072798A) is simple to operate, the binding force between silver ions and the substrate is weak, resulting in severe initial burst release, leading to a short effective antibacterial period and a high risk of cytotoxicity. Second, in terms of promoting healing, existing silver-containing foam dressings are mostly passively applied, lacking sufficient biological activity. Traditional silver-containing dressings focus on antibacterial properties while neglecting the biological needs of wound repair, making it difficult to actively promote cell proliferation, migration, and granulation tissue formation. Furthermore, the rapid release of silver ions can easily cause toxicity to newly formed cells in the wound while inhibiting bacteria, triggering an inflammatory response and thus delaying the healing process.

[0003] Based on this, the present invention will provide a silver-containing polyurethane foam dressing with good antibacterial effect, stable release rate of antibacterial components, and the ability to promote healing, which is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a silver-containing polyurethane foam dressing and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A silver-containing polyurethane foam dressing is prepared by mixing component A and component B in a mass ratio of 1:0.6~2; Component A is an aqueous polyurethane prepolymer; Component B comprises the following raw material components in parts by weight: 70-90 parts deionized water, 5-10 parts surfactant, 5-10 parts hydrophilic agent, 2-5 parts thickener, and 4-8 parts silver-containing antibacterial agent.

[0006] Furthermore, the waterborne polyurethane prepolymer includes, but is not limited to, one or more combinations of WanSponge WDT, WanSponge WMD, WanSponge VT102, Baymedix FP520, and Baymedix FP504.

[0007] Furthermore, the surfactant is a nonionic surfactant, including but not limited to one or more combinations of Span 20, Span 60, Span 80, Tween 20, Tween 60, Tween 80, Pluronic PE6200, Pluronic PE6400, Pluronic PE6800, Poloxamer 407, Poloxamer 188, Brij S2, and BASF 1000NI.

[0008] Furthermore, the hydrophilic agent includes, but is not limited to, one or more combinations of PEG600, PEG1000, PEG2000, PEG4000, PEG8000, and PEG20000.

[0009] Furthermore, the thickener includes, but is not limited to, one or more combinations of hydroxyethyl cellulose, xanthan gum, guar gum, and hydroxymethyl ethyl cellulose.

[0010] Furthermore, the silver-containing antibacterial agent is either a soluble silver salt or nano-silver.

[0011] Furthermore, component B also includes: 4-8 parts of modified chitosan and 1-2 parts of plant polyphenols.

[0012] Further, the preparation method of the modified chitosan is as follows: (1) Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir and react at 60~80℃ for 3~6h, add excess ethanol, precipitate out, filter, wash and freeze dry to obtain quaternized chitosan; (2) Dissolve dextran in deionized water, then add sodium periodate, stir and react in the dark for 2~4h, purify by dialysis and freeze dry to obtain aldehyde-modified dextran; (3) Dissolve amino acids and quaternized chitosan in deionized water, then add aldehyde-modified dextran, stir and react for 30~60min, freeze dry to obtain modified chitosan.

[0013] Furthermore, the ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate, and deionized water is 2~4g:0.6~1g:0.01~0.02g:50~100mL.

[0014] Furthermore, the ratio of the dextran to deionized water is 10~15g:100mL.

[0015] Furthermore, the molar ratio of the dextran to sodium periodate is 1~2:1; wherein the molecular weight of the dextran is 10000~50000g / mol.

[0016] Furthermore, the ratio of the amino acid, quaternized chitosan, aldehyde-modified dextran, and deionized water is 1.5~2g:3~4g:0.08~0.12g:50~100mL.

[0017] Furthermore, the amino acids include, but are not limited to, one or more combinations of lysine, leucine, isoleucine, valine, and threonine.

[0018] This invention prepares quaternized chitosan by reacting the carboxyl group of carboxymethyl chitosan with the epoxy group of glycidyltrimethylammonium chloride; then, it aldehyde-modifies dextran to obtain aldehyde-modified dextran; finally, it uses aldehyde-modified dextran as a grafting bridge to graft amino acids and quaternized chitosan together through a Schiff base reaction to prepare modified chitosan.

[0019] Through grafting modification, quaternary ammonium salt structures, dextran segments, and small-molecule amino acids were introduced into the modified chitosan. The quaternary ammonium salt structure directly enhances the antibacterial and healing-promoting effects of carboxymethyl chitosan and also improves its dispersibility. However, the degree of quaternization should not be too high, as quaternary ammonium salts can irritate wounds and cause allergies. Since the pH of exudate from a normal wound is between 5.0 and 6.5, under this acidic pH environment, the Schiff base structure begins to slowly hydrolyze. Therefore, the Schiff base structure in the modified chitosan begins to hydrolyze and release small-molecule amino acids. The release of these amino acids further lowers the pH, thereby further promoting the hydrolysis of the Schiff base structure in the modified chitosan. The large amount of released amino acids is absorbed and utilized by the wound to reduce inflammation and promote wound healing. The dextran segments obtained from the hydrolysis have no toxic effect on cells and can also stimulate tissue growth and promote wound healing. Therefore, the modified chitosan can be uniformly dispersed in polyurethane foam, thus exerting antibacterial and healing-promoting effects. The reason for choosing to introduce amino acids into chitosan through the Schiff base reaction in the plan is that if amino acids are added directly to the raw material components, the amino acids will react with the waterborne polyurethane prepolymer, affecting the stability of foaming, and the amino acids are not easy to release.

[0020] Furthermore, because modified chitosan is uniformly dispersed in polyurethane foam and contains polar groups, it can form a three-dimensional network structure in polyurethane foam dressings, which can restrict the movement of silver-containing antibacterial agents and prevent their rapid release. When there is a lot of exudate from the wound, the Schiff base structure in the modified chitosan hydrolyzes faster, and the silver-containing antibacterial agent will dissociate and be released more quickly. When there is less exudate from the wound, the silver-containing antibacterial agent is released slowly. Combined with modified chitosan and plant polyphenols, it can also achieve a good antibacterial effect.

[0021] Furthermore, the plant polyphenols are tea polyphenols or chlorogenic acid.

[0022] This invention further incorporates plant polyphenols. On one hand, plant polyphenols possess antioxidant, anti-inflammatory, and antibacterial properties, which can alleviate wound inflammation and promote wound healing. On the other hand, plant polyphenols can form hydrogen bonds with polyurethane foam and modified chitosan, helping to improve the toughness of polyurethane foam and making its quality more stable. The plant polyphenols chosen are tea polyphenols or chlorogenic acid because: lower molecular weight allows for faster penetration through wound exudate and absorption; however, lower molecular weight also makes them more prone to loss with the exudate, reducing the amount of plant polyphenols actually absorbed and utilized; furthermore, higher molecular weight means more hydroxyl groups, leading to stronger hydrogen bonds. Excessive or overly dense hydrogen bonds can increase foam brittleness, causing polyurethane foam to break and reducing overall performance. Therefore, plant polyphenols with a medium molecular weight (300-600 g / mol) are more suitable.

[0023] Furthermore, the preparation method of the silver-containing polyurethane foam dressing includes the following steps: Step 1: According to the formula ratio, first stir and mix the raw materials of component B at a speed of 30~50 rpm for 30~40 minutes; then stir and mix component A with it at a speed of 2000~8000 rpm for 1~3 minutes to obtain component C; Step 2: Quickly extrude component C between two release papers to form foam. Adjust the foam thickness to 1.5~8mm, keep it at 40~90℃ for 10~20min, then dry it at 100~105℃ for 4~10min, and finally sterilize it by irradiation to obtain silver-containing polyurethane foam dressing.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) The silver-containing polyurethane foam dressing prepared by the present invention encapsulates the silver-containing antibacterial agent in the foam. Taking advantage of the porous structure and large contact surface area of ​​polyurethane foam, it can stably and continuously release silver ions after absorbing a large amount of wound exudate, and the antibacterial performance is long-lasting. At the same time, the encapsulation effect of the foam can effectively reduce the risk of large accumulation of silver-containing antibacterial agent in skin tissue, avoid excessive local concentration, and also greatly alleviate the toxicity risk caused by silver-containing antibacterial agent directly entering the blood.

[0025] (2) In this invention, modified chitosan and plant polyphenols are further added to the silver-containing polyurethane foam dressing. Both have good biocompatibility and are not irritating to the skin. They can work together with the silver-containing antibacterial agent to form an enhanced antibacterial system, which significantly enhances the antibacterial performance of the polyurethane foam dressing.

[0026] (3) The silver-containing polyurethane foam dressing prepared by the present invention has a significant healing-promoting effect; under the action of acidic exudate in the wound, the modified chitosan releases small molecule amino acids and dextran segments, which can promote healing; plant polyphenols can further promote healing; the two work together to achieve a highly efficient healing-promoting effect.

[0027] (4) The silver-containing polyurethane foam dressing prepared by the present invention has the effect of slow release of silver-containing antibacterial agent; the modified chitosan forms a uniform three-dimensional network structure in the polyurethane foam dressing, which has a certain restriction effect on the movement path of silver-containing antibacterial agent and avoids the rapid release of silver-containing antibacterial agent; when the wound is severely injured and there is a lot of exudate, the Schiff base structure in the modified chitosan hydrolyzes faster, and the silver-containing antibacterial agent will dissociate and be released faster, which enhances the antibacterial performance; when the wound is less injured and there is less exudate, the silver-containing antibacterial agent is released slowly, and the combination of modified chitosan and plant polyphenols can also achieve a good antibacterial effect.

[0028] (5) The silver-containing polyurethane foam dressing prepared by the present invention has a uniform and stable content of silver antibacterial agent in the foam, which can ensure that the antibacterial performance of the product remains consistent.

[0029] (6) The silver-containing polyurethane foam dressing prepared by the present invention has a long-lasting antibacterial ability, which can avoid frequent replacement during the use of the wound, saving medical expenses for patients and saving a lot of medical resources.

[0030] (7) The silver-containing polyurethane foam dressing prepared by the present invention has a simple preparation process. The silver-containing antibacterial agent is added before the polyurethane material is foamed, and there is no need to add antibacterial components to the polyurethane foam material that has been foamed. The process of adding antibacterial components by means of impregnation, spraying, cross-linking, etc. is eliminated, which greatly improves production efficiency and saves energy. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplarily, they include: WanSponge WDT waterborne polyurethane prepolymer; Span 20; PEG600; silver nitrate; xanthan gum (CAS No. 109898-97-7); carboxymethyl chitosan (degree of deacetylation 85-90%, degree of carboxylation ≥80%); glycidyltrimethylammonium chloride; ferric chloride hexahydrate; sodium periodate; dextran (molecular weight 30000 g / mol); lysine (CAS No. 56-87-1); leucine (CAS No. 26782-71-8); isoleucine (CAS No. 26782-71-8); and isoleucine (CAS No. 26782-71-8). The ingredients are: 131598-62-4; valine, CAS number 7004-03-7; threonine, CAS number 72-19-5; gallic acid, CAS number 149-91-7; catechin, CAS number 130405-40-2; tea polyphenols, CAS number 84650-60-2; chlorogenic acid, CAS number 327-97-9; tannic acid, CAS number 1401-55-4; all raw materials are commercially available; each part by weight is 100g.

[0033] Example 1: A method for preparing a silver-containing polyurethane foam dressing: Step 1: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, and 6 parts silver nitrate at 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at 5000 rpm for 2 min to obtain component C; Step 2: Quickly extrude component C between two release papers to form foam. Adjust the foam thickness to 3 mm, keep it at 60°C for 15 minutes, and finally dry it at 105°C for 7 minutes to obtain silver-containing polyurethane foam dressing.

[0034] Performance Test 1: The silver-containing polyurethane foam dressing prepared in Example 1 was subjected to the following performance tests: 1. Silver ion release performance test: The silver-containing polyurethane foam dressing was cut into 10cm×10cm samples and immersed in physiological saline at 37℃ with pH=5.0 and pH=7.0 for 12h, 24h, 36h, 48h, 60h and 72h respectively. The samples were then removed and the silver ion content in the immersion solution was tested using an inductively coupled plasma atomic emission spectrometer. The average value of the 5 samples was taken as the silver ion release amount. 2. Antibacterial performance test: The silver-containing polyurethane foam dressing was cut into 10cm × 10cm samples, placed in an Erlenmeyer flask, and inoculated with 1mL of Staphylococcus aureus solution (1.5 × 10⁻⁶). 5 ~3×105 The culture was carried out at 37℃ with an oscillation speed of 200 r / min for 1 day and 2 days. The absorbance of the eluent in each flask after 1 day and 2 days of culture was measured at 570 nm using a spectrophotometer. The antibacterial rate was calculated according to the formula: (AB) / A×100%=antibacterial rate, where A is the absorbance value of the bacterial solution in the control group and B is the absorbance value of the corresponding cell solution in the experimental group.

[0035] 3. Liquid absorption performance test: The liquid absorption performance was tested according to the standards YY / T 1293.2-2022 and YY / T 0471.1-2004, with an absorption time of 30 minutes.

[0036] The specific test data results are shown in Table 1: Table 1

[0037] Based on Example 1, modified chitosan and tea polyphenols were further added to create Example 2, as detailed below: Example 2: A method for preparing a silver-containing polyurethane foam dressing: Step 1: Preparation of modified chitosan: (1) Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir at 70°C for 5 h, add excess ethanol, precipitate out, filter, wash, and freeze dry to obtain quaternized chitosan, wherein the ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate and deionized water is 3g:0.8g:0.015g:75mL; (2) Dissolve dextran in deionized water, then add sodium periodate, stir in the dark for 3 h, purify by dialysis, freeze dry to obtain Aldehyde-modified dextran, wherein the ratio of dextran to deionized water is 12.5g:100mL, and the molar ratio of dextran to sodium periodate is 1.5:1; (3) Amino acids (lysine, leucine, isoleucine, valine, and threonine are mixed in a mass ratio of 1:1:1:1:1) and quaternized chitosan are dissolved in deionized water, and then aldehyde-modified dextran is added. The mixture is stirred for 45 minutes and then freeze-dried to obtain modified chitosan, wherein the ratio of amino acids, quaternized chitosan, aldehyde-modified dextran, and deionized water is 1.75g:3.5g:0.1g:75mL; Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 1.5 parts tea polyphenols at 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at 5000 rpm for 2 min to obtain component C; Step 3: Quickly extrude component C between two release papers to form foam. Adjust the foam thickness to 3 mm, keep it at 60°C for 15 minutes, and finally dry it at 105°C for 7 minutes to obtain silver-containing polyurethane foam dressing.

[0038] Performance Test 2: The silver-containing polyurethane foam dressing prepared in Example 2 was also subjected to silver ion release performance test, antibacterial performance test, and liquid absorption performance test in sequence. The specific test results are shown in Table 2 below: Table 2

[0039] Result Analysis 1: Comparing the data in Table 1 and Table 2 above, we can see that: (1) In terms of the amount of silver ions released, the silver-containing polyurethane foam dressing prepared in Example 1 showed a relatively fast silver ion release rate under pH=5.0 and 7.0 conditions, and was almost completely released in about 36 hours. The silver-containing polyurethane foam dressing prepared in Example 2 maintained a stable silver ion release rate within 72 hours under pH=7.0 conditions, showing excellent slow-release stability; while under pH=5.0 conditions, the silver ion release rate was significantly accelerated. The reason is that this pH condition is to simulate the pH of wound exudate. Under this pH condition, the Schiff base structure in the modified chitosan will be hydrolyzed, and the silver ions will be released more quickly. In practical applications, the wound initially releases a lot of exudate, but as it begins to heal over time, the exudate gradually decreases. At this time, the release rate of silver ions gradually slows down. Therefore, it will not release silver ions at a fast rate as in the experiment, but will gradually become a slow release. After the wound begins to heal, the amount of silver ions released will gradually decrease. Of course, there is no need to worry about the antibacterial properties of the polyurethane foam dressing decreasing. With the synergistic effect of modified chitosan and plant polyphenols, the antibacterial properties of the polyurethane foam dressing can still be guaranteed. (2) In terms of antibacterial rate, the silver-containing polyurethane foam dressing prepared in Example 2 shows better antibacterial properties under the synergistic effect of silver-containing antibacterial agent, modified chitosan and plant polyphenols. (3) In terms of liquid absorption, the silver-containing polyurethane foam dressing prepared in Example 2 can absorb more exudate, which is more in line with the clinical wound care needs. In addition, in Example 2, the amount of silver ion release can be dynamically adjusted according to the amount of exudate from the wound, which can play a role in enhancing the antibacterial properties in real time.

[0040] Therefore, the silver-containing polyurethane foam dressing prepared in Example 2 has superior performance.

[0041] Based on this, the following examples, 3-7 and 1-11, are set up according to Example 2, as follows: Example 3: A method for preparing a silver-containing polyurethane foam dressing: Example 3 is based on Example 2, but with the following adjustment: the amount of glycidyl trimethylammonium chloride in the quaternized chitosan modified raw material remains unchanged. Specifically: Step 1: Preparation of modified chitosan: (1) Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir and react at 70°C for 5 hours, add excess ethanol, precipitate out, filter, wash and freeze dry to obtain quaternized chitosan, wherein the ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate and deionized water is 3g:1g:0.015g:75mL.

[0042] Example 4: A method for preparing a silver-containing polyurethane foam dressing: Example 4 is based on Example 2, but with the following adjustment: the amount of glycidyl trimethylammonium chloride in the quaternized chitosan modified raw material remains unchanged. Specifically: Step 1: Preparation of modified chitosan: (1) Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir and react at 70°C for 5 hours, add excess ethanol, precipitate out, filter, wash and freeze dry to obtain quaternized chitosan, wherein the ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate and deionized water is 3g:0.6g:0.015g:75mL.

[0043] Example 5: A method for preparing a silver-containing polyurethane foam dressing: Example 5 is based on Example 2, but with adjustments made to the amount of raw material components in the silver-containing polyurethane foam dressing, while keeping other processes unchanged. Specifically: Step 2: (1) Mix 70 parts deionized water, 5 parts Span 20, 5 parts PEG600, 2 parts xanthan gum, 4 parts silver nitrate, 4 parts modified chitosan, and 1 part tea polyphenol at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0044] Example 6: A method for preparing a silver-containing polyurethane foam dressing: Example 6 is based on Example 2, but with the following adjustment: the amount of glycidyl trimethylammonium chloride in the quaternized chitosan modified raw material remains unchanged. Specifically: Step 2: (1) Mix 90 parts deionized water, 10 parts Span 20, 10 parts PEG600, 5 parts xanthan gum, 8 parts silver nitrate, 8 parts modified chitosan, and 2 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0045] Example 7: A method for preparing a silver-containing polyurethane foam dressing: Example 7 is based on Example 2, with the following adjustment: chlorogenic acid was used instead of plant polyphenols, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 1.5 parts chlorogenic acid at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0046] Comparative Example 1: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 1 is based on Example 2, with the following adjustment: the amount of modified chitosan was adjusted, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 3 parts modified chitosan, and 1.5 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0047] Comparative Example 2: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 2 is based on Example 2, but with the following adjustment: the amount of modified chitosan was adjusted, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 9 parts modified chitosan, and 1.5 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0048] Comparative Example 3: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 3 is based on Example 2, but with the following adjustment: the amount of tea polyphenols was adjusted, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 0.9 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0049] Comparative Example 4: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 4 is based on Example 2, but with the following adjustment: the amount of tea polyphenols was adjusted, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 2.1 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0050] Comparative Example 5: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 5 is based on Example 2, with the following adjustment: the carboxymethyl chitosan was not modified, while other processes remained unchanged. Specifically: Step 1: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts carboxymethyl chitosan, and 1.5 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0051] Comparative Example 6: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 6 is based on Example 2, with the following adjustments: the amino acids are not grafted with quaternized chitosan, while other processes remain unchanged. Specifically: Step 1: 1. Preparation of quaternized chitosan: Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir and react at 70℃ for 5h, add excess ethanol, precipitate out, filter, wash, and freeze dry to obtain quaternized chitosan. The ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate and deionized water is 3g:0.8g:0.015g:75mL. 2. Preparation of aldehyde-modified dextran: Dextran was dissolved in deionized water, and sodium periodate was added. The mixture was stirred in the dark for 3 hours. After purification by dialysis and freeze-drying, aldehyde-modified dextran was obtained. The ratio of dextran to deionized water was 12.5 g: 100 mL, and the molar ratio of dextran to sodium periodate was 1.5: 1. 3. Preparation of amino acids: Lysine, leucine, isoleucine, valine, and threonine are mixed in a mass ratio of 1:1:1:1:1 to obtain amino acids; Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 3.95 parts quaternized chitosan, 0.112 parts aldehyde-modified dextran, 1.96 parts amino acids, and 1.5 parts tea polyphenols at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0052] Comparative Example 7: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 7 is based on Example 2, but with the following adjustment: the amount of glycidyl trimethylammonium chloride in the quaternized chitosan modified raw material remains unchanged, specifically: Step 1: Preparation of modified chitosan: (1) Dissolve carboxymethyl chitosan and glycidyltrimethylammonium chloride in deionized water, then add ferric chloride hexahydrate, stir and react at 70°C for 5 h, add excess ethanol, precipitate out, filter, wash, and freeze dry to obtain quaternized chitosan, wherein the ratio of carboxymethyl chitosan, glycidyltrimethylammonium chloride, ferric chloride hexahydrate and deionized water is 3g:1.1g:0.015g:75mL; (2) Dissolve dextran in deionized water, then add sodium periodate, stir and react in the dark for 3 h, purify by dialysis and freeze dry to obtain Aldehyde-modified dextran, wherein the ratio of dextran to deionized water is 12.5g:100mL, and the molar ratio of dextran to sodium periodate is 1.5:1; (3) Amino acids (lysine, leucine, isoleucine, valine, and threonine are mixed in a mass ratio of 1:1:1:1:1) and quaternized chitosan are dissolved in deionized water, and then aldehyde-modified dextran is added. The mixture is stirred for 45 minutes and then freeze-dried to obtain modified chitosan, wherein the ratio of amino acids, quaternized chitosan, aldehyde-modified dextran, and deionized water is 1.75g:3.5g:0.1g:75mL.

[0053] Comparative Example 8: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 8 is based on Example 2, with the following adjustment: no plant polyphenols were added, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, and 6 parts modified chitosan at a speed of 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at a speed of 5000 rpm for 2 min to obtain component C.

[0054] Comparative Example 9: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 9 is based on Example 2, with the following adjustments: gallic acid was used instead of plant polyphenols, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 1.5 parts gallic acid at 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at 5000 rpm for 2 min to obtain component C.

[0055] Comparative Example 10: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 10 is based on Example 2, with the following adjustments: catechins were used instead of plant polyphenols, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 1.5 parts catechin at 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at 5000 rpm for 2 min to obtain component C.

[0056] Comparative Example 11: A method for preparing a silver-containing polyurethane foam dressing: Comparative Example 11 is based on Example 2, with the following adjustments: tannic acid was used instead of plant polyphenols, while other processes remained unchanged. Specifically: Step 2: (1) Mix 80 parts deionized water, 7.5 parts Span 20, 7.5 parts PEG600, 3.5 parts xanthan gum, 6 parts silver nitrate, 6 parts modified chitosan, and 1.5 parts tannic acid at 40 rpm for 35 min to obtain component B; (2) Mix component A and component B at a mass ratio of 1:1 and mix at 5000 rpm for 2 min to obtain component C.

[0057] Performance Test 3: Animal wound healing experiments were conducted on the silver-containing polyurethane foam dressings prepared in Examples 1-7 and Comparative Examples 1-11. The specific experimental methods are as follows: (1) Take 19 groups of mice (7-8 weeks old, 20±2g weight), corresponding to Example 1, Example 2...Example 10, Comparative Example 1, Comparative Example 2...Comparative Example 8, and control group, with 6 mice in each group. The mice were anesthetized by abdominal injection of 1% sodium pentobarbital. (2) Shave the hair off the back of the mouse and make a hole in the skin on its back to form a full-thickness skin defect with a diameter of 6 mm; (3) Add 1 mL of Staphylococcus aureus solution (1.5 × 10⁻⁶) 5 ~3×10 5 A drop of CFU / mL was placed in the center of the wound, and the bacterial solution was gently spread over the entire wound. Then, the silver-containing polyurethane foam dressing prepared in each example was applied to the wound and fixed with a 3M transparent and breathable dressing. The control group was bandaged with Vaseline gauze. After 7 days, the silver-containing polyurethane foam dressing was removed and the wound area was measured. (4) The wound area ratio of each case was calculated according to the formula: Wound area ratio (%) = (Wound area after 7 days / Initial wound area) × 100%, and the antibacterial and healing-promoting properties of silver-containing polyurethane foam dressing were evaluated.

[0058] The specific test results are shown in Table 3 below: Table 3

[0059] Results Analysis 2: From the data in Table 3 above, we can see that: (1) By comparing Example 2 with Example 1, Examples 5-6, and Comparative Examples 1-4, we can see that under the synergistic effect of modified chitosan and plant polyphenols, silver-containing polyurethane foam dressings exhibit superior antibacterial and healing-promoting effects, and both are indispensable; (2) By comparing Example 2 with Example 3-4 and Comparative Example 7, we can see that the degree of quaternization of carboxymethyl chitosan has a significant impact on the performance of silver-containing polyurethane foam dressings. If the degree of quaternization is too high, the wound will be stimulated, which will lead to a significant decrease in antibacterial and healing-promoting performance; (3) By comparing Example 2 with Example 7 and Comparative Examples 8-11, we can see that plant polyphenols and their molecular weight have a significant impact on the performance of silver-containing polyurethane foam dressings. The performance of the dressing is significantly affected. Among them, tea polyphenols and chlorogenic acid, as plant polyphenols, show better antibacterial and healing-promoting effects. (4) By comparing Example 2 and Comparative Example 5, it can be seen that the carboxymethyl chitosan was not modified and no quaternary ammonium salt structure, dextran chain segment, amino acid molecules, etc. were introduced. Therefore, the silver-containing polyurethane foam dressing showed a significant decrease in antibacterial and healing-promoting effects. (5) By comparing Example 2 and Comparative Example 6, it can be seen that if aldehyde-modified dextran is not used to crosslink and modify amino acids and quaternized chitosan, amino acids will participate in the reaction with waterborne polyurethane prepolymer, which will affect the foaming of polyurethane foam dressing to a certain extent and make it difficult for amino acids to be released. Therefore, the antibacterial and healing-promoting effects are also significantly reduced.

[0060] In summary, this invention has comprehensively prepared a silver-containing polyurethane foam dressing with excellent antibacterial and healing-promoting properties. The silver-containing antibacterial agent it contains also has a sustained-release effect, which better meets the needs of clinical wound care.

[0061] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. 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 silver-containing polyurethane foam dressing, characterized in that: It is prepared by mixing component A and component B in a mass ratio of 1:0.6~2; Component A is an aqueous polyurethane prepolymer; Component B comprises the following raw material components in parts by weight: 70-90 parts deionized water, 5-10 parts surfactant, 5-10 parts hydrophilic agent, 2-5 parts thickener, and 4-8 parts silver-containing antibacterial agent; The silver-containing antibacterial agent is a soluble silver salt or nano-silver; Component B further includes: 4-8 parts of modified chitosan and 1-2 parts of plant polyphenols; The modified chitosan is prepared by: (1) adding carboxymethyl chitosan, glycidyltrimethylammonium chloride and ferric chloride hexahydrate to deionized water, stirring and reacting at 60~80℃, adding excess ethanol, precipitating the precipitate, filtering, washing and freeze-drying to obtain quaternized chitosan; (2) adding dextran and sodium periodate to deionized water, stirring and reacting in the dark, purifying by dialysis and freeze-drying to obtain aldehyde-modified dextran; (3) adding amino acids, quaternized chitosan and aldehyde-modified dextran to deionized water, stirring and reacting, and freeze-drying to obtain modified chitosan; The plant polyphenols are either tea polyphenols or chlorogenic acid.

2. The silver-containing polyurethane foam dressing according to claim 1, characterized in that: The waterborne polyurethane prepolymer includes one or more combinations of WanSponge WDT, WanSponge WMD, WanSponge VT102, Baymedix FP520, and Baymedix FP504.

3. The silver-containing polyurethane foam dressing according to claim 1, characterized in that: The surfactant is a nonionic surfactant, including one or more of Span 20, Span 60, Span 80, Tween 20, Tween 60, Tween 80, Pluronic PE6200, Pluronic PE6400, Pluronic PE6800, Poloxamer 407, Poloxamer 188, Brij S2, and BASF 1000NI; The hydrophilic agent includes one or more combinations of PEG600, PEG1000, PEG2000, PEG4000, PEG8000, and PEG20000; The thickener includes one or more of hydroxyethyl cellulose, xanthan gum, guar gum, and hydroxymethyl ethyl cellulose.

4. The silver-containing polyurethane foam dressing according to claim 1, characterized in that: In the raw materials of the quaternized chitosan, the ratio of carboxymethyl chitosan, glycidyl trimethylammonium chloride, ferric chloride hexahydrate, and deionized water is 2~4g:0.6~1g:0.01~0.02g:50~100mL.

5. The silver-containing polyurethane foam dressing according to claim 1, characterized in that: In the raw materials of the aldehyde-modified dextran, the molar ratio of dextran to sodium periodate is 1~2:1; the ratio of dextran to deionized water is 10~15g:100mL; and the molecular weight of dextran is 10000~50000g / mol.

6. The silver-containing polyurethane foam dressing according to claim 1, characterized in that: In the raw materials for modified chitosan, the ratio of amino acids, quaternized chitosan, aldehyde-modified dextran, and deionized water is 1.5~2g:3~4g:0.08~0.12g:50~100mL. The amino acids include one or more combinations of lysine, leucine, isoleucine, valine, and threonine.

7. A method for preparing a silver-containing polyurethane foam dressing according to any one of claims 1 to 6, characterized in that: Includes the following steps: Step 1: First, mix the raw materials of component B according to the formula ratio, and then mix component A with it to obtain component C; Step 2: Quickly extrude component C between two release papers to form foam. Adjust the thickness of the foam, and then insulate, dry, and sterilize by irradiation to obtain silver-containing polyurethane foam dressing.

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