Medical gauze modified with enzyme-responsive antibacterial hydrogel coating and preparation method thereof

Abstract

The present invention provides a medical gauze modified with an enzyme-responsive antibacterial hydrogel coating and a preparation method thereof. The method comprises the following steps: pretreating the medical gauze with a polyisocyanate-based polyurethane to obtain a medical gauze modified with an isocyanate group; immersing the medical gauze in a coating liquid containing anionic polysaccharides, antibacterial antibiotic trimethoprim, bactericidal aminoglycoside antibiotics and a polyisocyanate-based polyurethane crosslinker, and preparing the medical gauze by crosslinking the polyisocyanate-based polyurethane under high temperature conditions. In the present invention, the medical gauze provides good physical and mechanical properties, and the highly hydrophilic hydrogel coating covalently loads urease-sensitive antibacterial and bactericidal antibiotics in the form of urea bonds, thereby realizing the intelligent and efficient antibacterial function of enzyme response, improving the bioavailability of antibiotics, and minimizing the risk of bacterial resistance. In addition, the hydrogel coating can effectively avoid adhesion between tissue and gauze, and reduce secondary damage when changing dressings.

Description

Technical Field

[0001] The invention belongs to the technical field of antibacterial medical dressings, and particularly relates to a medical gauze modified with an enzyme-responsive antibacterial hydrogel coating and a preparation method thereof. Background Art

[0002] Medical gauze made of cotton fiber has become the most widely used dry dressing in clinical practice due to its softness, breathability, low cost, ease of use and good physical and mechanical properties. Medical gauze keeps wounds dry by absorbing exudate, but lacks antibacterial properties. The absorbed exudate provides nutrients and moisture for the growth of pathogens, which can easily cause infection. Although antibiotics can be used to reduce the risk of infection, the problem of drug-resistant bacteria still exists. In addition, gauze easily adheres to the wound after absorbing exudate, which may cause secondary damage during dressing changes. These problems limit the application of gauze in chronic wound care. Therefore, ideal medical dressings need to have antibacterial and anti-adhesion functions.

[0003] In recent years, hydrogels have become effective materials for preventing postoperative adhesions due to their superior water retention, biocompatibility, and ability to promote cell proliferation and migration. More ideally, the three-dimensional network structure of hydrogels can achieve antibacterial function by physically loading antibiotics, so they have attracted much attention in the field of new wound dressings. However, the water absorption and swelling characteristics of hydrogels lead to poor mechanical properties, which limits their clinical application. At the same time, the imprecision and uncontrollability of the sustained release of physically loaded antibiotics still poses a risk of bacterial resistance. In addition, the concentration-dependent antibacterial behavior of a single type of antibiotic seriously affects the effectiveness of its release.

[0004] Therefore, how to develop a medical dressing with good physical and mechanical properties, intelligent and efficient antibacterial properties, and anti-wound adhesion has become a problem to be solved in the field of medical dressings. Summary of the invention

[0005] In view of the technical problems of medical gauze and hydrogel, the present invention provides a medical gauze modified with an enzyme-responsive antibacterial hydrogel coating and a preparation method thereof. By combining the advantages of medical gauze and hydrogel, the present invention modifies an intelligent enzyme-responsive antibacterial hydrogel coating on the surface of the gauze to prepare an antibacterial and anti-adhesion dressing with excellent physical and mechanical properties. In this design, the medical gauze provides good physical and mechanical properties, and the highly hydrophilic hydrogel coating covalently loads urease-sensitive antibacterial and bactericidal antibiotics in the form of urea bonds. In the absence of infection, the coating has good resistance to hydrolysis to prevent the ineffective release of antibiotics. When bacteria invade, the urease in the bacterial metabolites can effectively catalyze the hydrolysis of the urea bonds inside the coating, release antibiotics on demand to prevent bacterial infection, improve the bioavailability of the drug, and minimize the risk of bacterial resistance. In addition, the hydrogel coating has an anti-adhesion function, effectively prevents adhesion between the dressing and the wound, and reduces secondary damage when changing the dressing.

[0006] To achieve the above object, the present invention provides the following specific technical solutions:

[0007] A method for preparing medical gauze modified with an enzyme-responsive antibacterial hydrogel coating comprises the following steps:

[0008] (1) Immersing medical gauze in an acetone solution of a polyisocyanate-based polyurethane crosslinking agent, and obtaining isocyanate-modified medical gauze after high-temperature reaction, cooling, rinsing, and vacuum drying; wherein, preferably, the concentration of the acetone solution of the polyisocyanate-based polyurethane crosslinking agent is 20-25wt%, and the treatment process conditions are preferably: high-temperature reaction conditions are 100-120°C, time 3-5h; acetone rinsing 3-5 times; vacuum drying conditions are -1.0 to -1.5mPa, temperature 70-80°C, time 2-3h.

[0009] (2) anionic polysaccharide compound, antibacterial antibiotic trimethoprim, aminoglycoside antibiotic, polyisocyanate polyurethane crosslinking agent and deionized water are stirred to prepare a coating liquid; wherein, preferably, the coating liquid is composed of 10-20 parts of anionic polysaccharide compound, 5-10 parts of antibacterial antibiotic trimethoprim, 5-10 parts of aminoglycoside antibiotic, 1-5 parts of polyisocyanate polyurethane crosslinking agent and 65-79 parts of deionized water in terms of mass fraction;

[0010] (3) The medical gauze obtained by the pretreatment in step (1) is subjected to a dip-coating-thermal curing process and a deionized water rinsing step to prepare a medical gauze modified with a hydrogel coating. Preferably, the thermal curing temperature is 120-130° C., and the curing time is 1-2 h; the rinsing step is a deionized water rinse, preferably 5 times, and the rinsing water flow rate is 5 cm / s.

[0011] More preferably, the isocyanate value of the polyisocyanate-based polyurethane in steps (1) and (2) is 20 to 25 wt%.

[0012] Further preferably, the anionic polysaccharide compound is one or both of hyaluronic acid and sodium alginate with a molecular weight of 10 to 20 kDa.

[0013] More preferably, the aminoglycoside antibiotic is one or more of amikacin, tobramycin, and gentamicin.

[0014] The benefits of the present invention are as follows:

[0015] (1) Application function combination: Constructing a hydrogel coating on the surface of medical gauze with good physical and mechanical properties not only effectively avoids the problem of traditional medical gauze adhering to the wound during use, but also solves the defect of poor physical and mechanical properties of hydrogel dressings.

[0016] (2) Enzyme-responsive intelligent and efficient antibacterial behavior: Through the covalent reaction between the amino group of the antibiotic and the isocyanate group of the polyisocyanate crosslinker, the antibiotic is stably bound to the coating in the form of a urea bond. In the absence of infection, the coating has good resistance to hydrolysis, preventing the ineffective release of antibiotics. When bacteria invade, the bacterial metabolite urease can effectively catalyze the hydrolysis of the urea bonds inside the coating, releasing antibiotics on demand to kill bacteria. In addition, based on the synergistic antibacterial effect of bactericidal antibiotics aminoglycoside antibiotics and bacteriostatic antibiotic trimethoprim, the antibacterial performance of the released antibiotics is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Medical gauze modified with different drug-loaded hydrogel coatings and given drug concentrations within 48 hours in different urease solutions.

[0018] Figure 2 It is the cell survival rate after co-incubation of medical gauze modified with different drug-loaded hydrogel coatings with L929 cells.

[0019] Figure 3 These are images of supernatant cells after incubation of medical gauze modified with different drug-loaded hydrogel coatings with L929 cells.

[0020] Figure 4 It is the total amount of biofilm on the surface of medical gauze modified with different drug-loaded hydrogel coatings and bacteria after co-culture for 7 days.

[0021] Figure 5 It is the wound recovery rate after medical gauze modified with different drug-loaded hydrogel coatings is applied to mouse skin wounds.

[0022] Figure 6The number of bacteria in wound tissue after medical gauze modified with different drug-loaded hydrogel coatings was applied to mouse skin wounds for 20 days. DETAILED DESCRIPTION

[0023] In order to more clearly show the technical solutions and advantages of the present invention, now detailed description is given in conjunction with the following specific embodiments. It should be noted that these embodiments are only used to explain and illustrate the present invention and do not constitute a limitation thereto. Non-essential improvements and adjustments made by those skilled in the art on this basis are still within the protection scope of the present invention.

[0024] Example 1

[0025] Preparation of hydrogel coating modified medical gauze:

[0026] (1) Medical gauze (GA) was immersed in a 20 wt% polyisocyanate polyurethane crosslinking agent acetone solution and reacted at 100°C for 3 hours. After cooling to room temperature, it was rinsed with acetone for 3 times and then dried under a vacuum environment of -1.01 mPa and 75°C for 2 hours to obtain isocyanate-modified medical gauze.

[0027] (2) 10 parts by mass of hyaluronic acid (CS), 5 parts by mass of antibacterial antibiotic trimethoprim (TMP), 5 parts by mass of amikacin (AMK), 2 parts by mass of a polyisocyanate-based polyurethane crosslinking agent, and 78 parts by mass of deionized water were stirred to prepare a coating liquid.

[0028] (3) The medical gauze obtained by the pretreatment in step (1) was immersed in the coating solution prepared in step (2) for 20 seconds, taken out and cured at 130° C. for 2 hours. It was then rinsed 5 times in deionized water at a flow rate of 5 cm / s to obtain a medical gauze modified with a hydrogel coating, which was named CS / TMP / AMK-GA.

[0029] Comparative Example 1

[0030] The coating solution was prepared by stirring 10 parts of hyaluronic acid (CS), 10 parts of antibacterial antibiotic trimethoprim (TMP), 2 parts of polyisocyanate polyurethane crosslinker, and 78 parts of deionized water according to mass fraction. The medical gauze modified with hydrogel coating containing only antibacterial antibiotic TMP was prepared by the same preparation method and named CS / TMP-GA.

[0031] Comparative Example 2

[0032] The coating solution was prepared by stirring 10 parts of CS, 10 parts of bactericidal antibiotic AMK, 2 parts of polyisocyanate-based polyurethane crosslinker and 78 parts of deionized water according to mass fraction. The same preparation method was used to prepare medical gauze modified with a hydrogel coating containing only bactericidal antibiotic AMK, named CS / AMK-GA.

[0033] Test Example 1

[0034] Enzyme stimulation response behavior of the coating: 5g of CS / TMP / AMK-GA prepared in Example 1, CS / TMP-GA prepared in Comparative Example 1, and CS / AMK-GA prepared in Comparative Example 2 were respectively immersed in a PBS solution containing urease, and a PBS solution without urease was used as a control (the response curves of the three samples in the PBS solution without urease overlapped, marked as control). Incubate at 37°C and 120rpm. The incubation solution was collected at 12h, 24h, 36h, and 48h, and the antibiotic content therein was measured and calculated by ultraviolet spectrophotometry. The results are shown in FIG. Figure 1 As shown in the figure, antibiotics were detected in the incubation solution containing urease, and the antibiotic content increased with the extension of incubation time. However, no antibiotics were detected in the control solution without urease. This indicates that urease can specifically hydrolyze the urea bond in the coating, thereby releasing antibiotics.

[0035] Test Example 2

[0036] Cytotoxicity evaluation: 200 mg of CS / TMP / AMK-GA in Example 1, CS / TMP-GA in Comparative Example 1, and CS / AMK-GA in Comparative Example 2 were co-cultured with 200 μL of L929 cell suspension (10^5 cells per well) in a 96-well plate. The test sample solution was obtained by culturing at 37°C and 5% CO2 for 1 day and 3 days. The cell viability was detected using a CCK-8 kit. The viability of L929 cells cultured in fresh culture medium was set to 100% (blank group), and the culture medium without L929 cells was set to the control group. The results are shown in the figure. Figure 2 As shown in the figure, there was no significant difference in cell survival rate between the three groups of hydrogel-coated gauze samples and the blank group. In addition, the cells in the supernatant were stained with calcein PBS solution, and the cell morphology was observed using a fluorescence microscope. Figure 3 As shown in the figure, there is no significant difference in cell morphology between the three groups of hydrogel-coated gauze samples and the blank group. The results show that the hydrogel-coated gauze has good biocompatibility.

[0037] Test Example 3

[0038] Evaluation of antibacterial properties: 5g of medical gauze prepared in Example 1, Comparative Example 1 and Comparative Example 2 were co-cultured with 10mL of nutrient broth (0.2wt%) containing 6×10^5CFU / mL bacteria for 48h, and the antibacterial rates of the three hydrogel coating-modified medical gauze were calculated by plate counting method. In this test, the bacterial models selected were Proteus mirabilis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus. The results are shown in Table 1. Compared with the blank GA group, the three groups of hydrogel coating-modified CS / TMP / AMK-GA, CS / TMP-GA and CS / AMK-GA all showed bactericidal ability. This is because the urease produced by bacteria during proliferation hydrolyzes the urea bond in the coating and releases antibiotics. However, the antibacterial rates of CS / TMP / AMK-GA against the four bacteria were all over 99.9%, compared with the antibacterial rates of CS / TMP-GA and CS / AMK-GA below 75%, indicating that the synergistic effect of the bacteriostatic antibiotic TMP and the bactericidal antibiotic AMK significantly improved the antibacterial effect.

[0039] Table 1. Antibacterial rates of medical gauze modified with different hydrogel coatings and without coating

[0040]

[0041] Test Example 4

[0042] Evaluation of anti-biofilm performance: 5 g of medical gauze prepared in Example 1, Comparative Example 1 and Comparative Example 2 were co-cultured with 10 mL of nutrient broth (0.2 wt%) containing Pseudomonas aeruginosa (6×10^5 CFU / mL). Medical gauze samples were taken out every 24 hours and placed in new nutrient broth containing the same bacterial concentration for 7 days. The total amount of biofilm was quantitatively tested using crystal violet staining. The results are shown in Figure 2. Figure 4 As shown, it is obvious that the amount of biofilm on the surface of CS / TPM / AMK-GA prepared in Example 1 is significantly lower than that of the blank GA group, Comparative Example 1 (CS / TMP-GA group) and Comparative Example 2 (CS / AMK-GA group), proving that CS / TPM / AMK-GA loaded with multiple types of antibiotics has better anti-biofilm performance.

[0043] Test Example 5

[0044] Evaluation of the performance of promoting wound healing in mice: After SD male rats (200±15g) were anesthetized with chloral hydrate, their back hair was removed with a shaver. A deep grade II burn was caused by placing a metal iron rod in boiling water and heating it to 100°C for 10 minutes, and then pressing it against the shaved rat skin for 10 seconds. Two symmetrical wounds were created on both sides of the back of each rat, for a total of four wounds. After 24 hours, surgical debridement was simulated using scissors and tweezers to obtain a grade II burn model of consistent depth. After blank GA, GA prepared in Example 1, Comparative Example 1 and Comparative Example 2 were fixed to the wound surface, the rats were placed in a 25°C environment for breeding, with 5 rats in each group. Photos of the wound area were taken on days 0, 4, 8, 12 and 20 to calculate the wound closure at each time point. On the 20th day, 200 mg of skin tissue was taken from the wound of each rat, homogenized in 5 ml of PBS, and the number of bacteria in the wound tissue homogenate was quantitatively tested by plate counting. The wound closure rate and the number of bacteria in wound tissue were Figure 5 and Figure 6 As shown. Compared with the blank GA group, comparative example 1 (CS / TMP-GA group) and comparative example 2 (CS / AMK-GA group), the CS / TPM / AMK-GA group prepared in Example 1 showed a higher wound recovery rate and a better degree of recovery. This is mainly attributed to the fact that the CS / TPM / AMK-GA group has the best antibacterial properties. During the recovery process, the number of bacteria in the wound tissue of mice in this group is the lowest, thereby promoting rapid wound healing.

[0045] Test Example 6

[0046] Evaluation of the performance of preventing postoperative tissue adhesion: After SD male rats (200 ± 15g) were anesthetized with chloral hydrate, the abdominal hair was removed and disinfected with medical iodine tincture. A 5 cm long incision was made along the white line of the abdominal wall using surgical scissors, and the cecal mucosal surface and the right abdominal wall were gently rubbed to cause bleeding damage. The rats in Group 1 were not treated in any way, and the cecum was directly fixed on the abdominal wall wound with 3-0 sutures to ensure full contact between the cecum and the abdominal wall as a positive control. Group 2 used blank GA, and Group 3 used CS / TMP / AMK-GA prepared in Example 1 to fit the damaged part of the cecum, and the suture operation was the same as that of Group 1. Each group contained 5 rats, and all operations were performed under sterile conditions, and antibiotics were given after surgery to prevent infection. On the 14th day after surgery, the rats were euthanized and the abdomen was cut open to observe the degree of adhesion. The standard adhesion scoring system was used for scoring: 0 points indicated no adhesion, 1 point indicated mild adhesion and easy separation, 2 points indicated moderate adhesion and can be separated by blunt peeling, and 3 points indicated severe adhesion and required sharp peeling. The scoring results are shown in Table 2. The average adhesion scores of the positive control group, blank GA group, and CS / TMP / AMK-GA group were 2.8, 2, and 0, respectively. The results showed that the CS / TMP / AMK-GA gauze modified with hydrogel coating can significantly prevent postoperative wound tissue adhesion and effectively avoid secondary injury to patients when removing the gauze.

[0047] Table 2 Postoperative adhesion scores of rats in different groups

[0048]

[0049] The above description is only part of the preferred embodiments of the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Claims

1. A method for preparing medical gauze modified with enzyme-responsive antibacterial hydrogel coating, characterized in that: The following steps are involved: (1) Immersing medical gauze in an acetone solution of a polyisocyanate-based polyurethane crosslinking agent, and obtaining isocyanate-modified medical gauze after high-temperature reaction, cooling, rinsing, and vacuum drying; the concentration of the acetone solution of the polyisocyanate-based polyurethane crosslinking agent is 20-25 wt%, and the high-temperature reaction is 100-120°C for 3-5 h; (2) Anionic polysaccharide compound, antibacterial antibiotic trimethoprim, aminoglycoside antibiotic, polyisocyanate polyurethane crosslinking agent and deionized water are stirred to prepare a coating liquid, wherein the coating liquid comprises 10-20 parts by weight of anionic polysaccharide compound, 5-10 parts by weight of antibacterial antibiotic trimethoprim, 5-10 parts by weight of aminoglycoside antibiotic, 1-5 parts by weight of polyisocyanate polyurethane crosslinking agent and 65-79 parts by weight of deionized water; the anionic polysaccharide compound is hyaluronic acid having a molecular weight of 10-20 kDa; (3) The medical gauze obtained by the pretreatment in step (1) is subjected to a dipping-heat curing process and a deionized water rinsing step to prepare a medical gauze modified with a hydrogel coating, wherein the temperature of the heat curing process is 120-130° C. and the curing time is 1-2 hours.

2. The method for preparing the enzyme-responsive antibacterial hydrogel coating-modified medical gauze according to claim 1, characterized in that: The isocyanate value of the polyisocyanate-based polyurethane in the polyisocyanate-based polyurethane crosslinking agent acetone solution is 20-25 wt%.

3. The method for preparing the enzyme-responsive antibacterial hydrogel coating modified medical gauze according to claim 1, characterized in that: The rinsing in step (1) is rinsing with acetone 3-5 times; the vacuum drying conditions are -1.0~-1.5mPa, temperature 70-80°C, and time 2-3 hours.

4. The method for preparing the medical gauze modified with the enzyme-responsive antibacterial hydrogel coating according to claim 1, characterized in that: The aminoglycoside antibiotics are one or more of amikacin, tobramycin and gentamicin.

5. A medical gauze modified with an enzyme-responsive antibacterial hydrogel coating, characterized in that: The enzyme-responsive antibacterial hydrogel coating-modified medical gauze is prepared by the method according to any one of claims 1 to 4.

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