An antibacterial hydrogel dressing for the treatment of infectious chronic wounds and a preparation method thereof

Abstract

The present invention provides an antibacterial hydrogel dressing for the treatment of infectious chronic wounds and a preparation method thereof. The dressing is made by directly coating a hydrogel on an antibacterial nanofiber membrane layer. The hydrogel is prepared from oxidized polysaccharide, dopamine-modified oxidized polysaccharide and aminated polysaccharide through Schiff base reaction. The antibacterial nanofiber membrane layer is prepared by electrospinning after blending a quaternary ammonium salt antibacterial agent with a nanofiber membrane substrate. The method of the present invention has mild conditions, is easy for industrial production, has low energy consumption, does not involve organic solvents, and has no pollution. The prepared hydrogel dressing has good biocompatibility, is non-toxic to the human body, has good antibacterial properties, can promote angiogenesis, and is beneficial to wound repair.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and particularly relates to an antibacterial hydrogel dressing for the treatment of infectious chronic wounds and a preparation method thereof. Background Art

[0002] As the first natural barrier of the human body, the skin can not only resist the invasion of external bacteria, dust, etc., block the damage of ultraviolet rays to the human epidermis, but also avoid the reduction of water in human tissues and organs, so as to play a role in protecting the human body. However, in daily life, it is inevitable that the skin will be damaged due to some physical impacts, chemical erosions or bacterial infections. The healing of skin wounds is an extremely complex process, involving the interaction of multiple interrelated factors. According to its damaged mode and severity, it can be divided into the following types: surgical wounds, traumas, chronic wounds, etc.

[0003] With the aging of the population and the acceleration of the pace of life, problems such as obesity and "three highs" are becoming increasingly prominent. The harm and burden brought by chronic wounds to humans are getting greater and greater, and even hinder the global economic development to a certain extent. At present, the definition of chronic wounds has not been uniformly defined. The Wound Healing Society defines chronic wounds as wounds that cannot achieve anatomical and functional integrity through a normal, orderly and timely repair process. As a typical case in the field of skin wounds, chronic wounds have attracted extensive attention from researchers and medical staff. Debridement, antibiotics, and hyperbaric oxygen therapy are the main current clinical means, but there are often problems such as low treatment efficiency, strong recurrence, and difficult operation in the treatment process, bringing double physical and psychological pressures to patients, thus causing problems such as low compliance and poor treatment effect in the treatment process of patients. At the same time, too much irrelevant treatment will instead cause difficulties in the repair of chronic wounds and cause a series of complications, which will increase the treatment cost of patients and even endanger the life safety of patients in severe cases. The research and development of ideal wound dressings is an effective means to rapidly promote the healing of chronic wounds.

[0004] The bacterial biofilm mentioned in the pathology of chronic wounds is a major inducer leading to the delayed healing of chronic wounds. Bacterial biofilms are aggregates of bacteria bound by extracellular polymeric substances (EPS). Bacteria in the biofilm can avoid being attacked by antibiotics and host innate immune cells due to the protection of EPS. Bacterial biofilms may also cause an excessive inflammatory response, thereby prolonging the release of inflammatory cytokines and activating immune complexes, resulting in delayed wound healing. Therefore, an ideal wound dressing needs to have good antibacterial and anti-inflammatory effects, mechanical stability and biocompatibility, and effectively regulate the wound microenvironment to promote rapid wound healing.

[0005] Hydrogels are three-dimensional soft materials with an interconnected porous structure. Their high water content can meet the requirements of the physiological environment for wound healing, making them ideal dressings for wound repair. However, conventional hydrogel dressings often have problems such as a relatively simple structure, weak mechanical properties, a long gelation time, easy bacterial growth, and poor wound adhesion. The inability to promptly drain wound exudate for a long time may also exacerbate wound deterioration and hinder wound healing. Summary of the Invention

[0006] The object of the present invention is to provide an antibacterial hydrogel dressing for the treatment of infectious chronic wounds and its preparation method. This dressing combines the characteristics of hydrogels and electrospinning technology, fully integrating the advantages of both, and has good biocompatibility and antibacterial properties, which is beneficial to regulating the wound microenvironment and promoting rapid wound repair.

[0007] Based on the above object, the present invention provides an antibacterial hydrogel dressing for the treatment of infectious chronic wounds. This dressing is made by directly coating a hydrogel on an antibacterial nanofiber membrane layer; the hydrogel is prepared from oxidized polysaccharides, dopamine-modified oxidized polysaccharides, and aminated polysaccharides through Schiff base reaction; the antibacterial nanofiber membrane layer is prepared by electrospinning after blending a quaternary ammonium salt antibacterial agent with a nanofiber membrane substrate. A nanofiber membrane / hydrogel composite dressing is formed through the adhesion and hydrogen bond action of the hydrogel.

[0008] Furthermore, the thickness of the antibacterial nanofiber membrane layer is 0.5 - 2 mm, preferably 1 mm; the coating amount of the hydrogel is 10 - 200 μL / cm 2 , preferably 100 μL / cm 2 .

[0009] Furthermore, the oxidized polysaccharide is one or more of oxidized carboxymethyl cellulose, oxidized dextran, and oxidized sodium alginate; the dopamine-modified oxidized polysaccharide is one or more of dopamine-modified oxidized carboxymethyl cellulose, dopamine-modified oxidized dextran, and dopamine-modified oxidized sodium alginate. The oxidized polysaccharide is prepared from polysaccharides as raw materials. After dissolving in water, an oxidizing agent is added for a light-avoiding reaction, and then purified by dialysis, centrifuged, and dried. The oxidizing agent used can be one or more of hydrogen peroxide, potassium permanganate, or sodium periodate. The mass ratio of polysaccharide to oxidizing agent is preferably 1:1 - 1.5; the oxidation reaction is a dark reaction, and the time is 6 - 24 h.

[0010] The dopamine-modified oxidized polysaccharide is obtained by dissolving the oxidized polysaccharide in water, adding dopamine for reaction under a nitrogen atmosphere, dialyzing, and drying; the mass ratio of oxidized polysaccharide to dopamine is 1 - 5:1 - 5.

[0011] Further, the amino polysaccharide is one or more of carboxymethyl chitosan, hyaluronic acid, chondroitin sulfate, heparin, chitosan, glucosamine, or other amino polysaccharide derivatives.

[0012] Further, the mass ratio of the oxidized polysaccharide, dopamine-modified oxidized polysaccharide, and aminated polysaccharide is 1-2:1-2:0.5-1.

[0013] Further, the antibacterial nanofiber membrane layer is at least a bilayer structure, and the spinning void size of the fiber membrane layer closer to the hydrogel side is larger than that of the fiber membrane layer farther from the hydrogel side. By the above setting, a bilayer electrospun nanofiber membrane with a void gradient is obtained, which realizes the unidirectional transfer of internal liquid to a certain extent and is more conducive to the effective healing of wounds.

[0014] Further, the quaternary ammonium salt antibacterial agent is one or more of cetyl dimethylethyl ammonium bromide, dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride, and dimethylhexadecyl [3-(trimethoxysilyl)propyl] ammonium chloride; the nanofiber membrane substrate is one or more of polyacrylonitrile, polycaprolactone, or polylactic acid.

[0015] Further, the nanofiber membrane substrate in the fiber membrane layer farther from the hydrogel side contains polycaprolactone and polylactic acid, and the mass ratio of the two is 2-5:1; the nanofiber membrane substrate in the fiber membrane layer closer to the hydrogel side is polyacrylonitrile.

[0016] The present invention also relates to a preparation method of the dressing, which is characterized by including the following steps:

[0017] S1. Prepare aqueous solutions of the oxidized polysaccharide, dopamine-modified oxidized polysaccharide, and amino polysaccharide respectively, mix them evenly in proportion, and then react at 20-37 °C for 1-10 min to obtain a hydrogel.

[0018] S2. Blend and graft the quaternary ammonium salt antibacterial agent and the nanofiber membrane substrate, add a solvent to prepare a spinning solution, and prepare an antibacterial nanofiber membrane through electrospinning.

[0019] S3. Coat the hydrogel obtained in S1 on the antibacterial nanofiber membrane obtained in S2 to obtain an antibacterial hydrogel dressing for the treatment of infectious chronic wounds.

[0020] Preferably, the concentrations of the oxidized polysaccharide and dopamine-modified oxidized polysaccharide are both 5-10% (w / v); the concentration of the amino polysaccharide aqueous solution is 3-8% (w / v), and the concentrations of the oxidized polysaccharide and dopamine-modified oxidized polysaccharide solutions are both 5-10% (w / v).

[0021] Preferably, when the quaternary ammonium salt antibacterial agent is blended and grafted with the nanofiber membrane substrate, the concentration of the quaternary ammonium salt antibacterial agent is 0.2-0.6 wt%.

[0022] The present invention also relates to the application of the dressing in the repair of infected chronic wounds.

[0023] The present invention has the following beneficial effects:

[0024] 1. The hydrogel prepared by the present invention using oxidized polysaccharide, dopamine-modified oxidized polysaccharide and amino polysaccharide as raw materials through Schiff base reaction gels rapidly, with mild reaction conditions, without the need for initiators and ultraviolet irradiation, and can react below 37°C. A large amount of oxidized polysaccharide and dopamine-modified oxidized polysaccharide coexist in the present invention, which can effectively avoid the situation where excessive aldehyde groups react with dopamine, resulting in insufficient mechanical properties or inability to form a hydrogel. The hydrogel can be in-situ transformed from a sol state to a gel state at the wound site, has excellent wound adaptability, can completely cover wounds with irregular shapes, and can follow the movement of the human body to achieve self-repair performance through the cleavage and reconstruction of Schiff base bonds, more closely adapting to the wound, especially chronic wounds with a deeper wound bed, thereby reducing the pain of patients.

[0025] 2. The hydrogel has good stability. When compounded with the nanofiber membrane, no other adhesives are required, and physical combination can be achieved by using the self-adhesion and hydrogen bond action of the hydrogel itself, forming a multiple and firm combination. The hydrogel has good moisture retention, liquid absorption and anti-adhesion effects, and the antibacterial nanofiber membrane has good mechanical properties, softness and antibacterial properties. The dressing has the common advantages of the hydrogel and the nanofiber membrane. The hydrogel layer is close to the skin, has good tissue affinity and wound fitting degree at the wound site, can maintain a moist environment at the wound and absorb wound exudate; the nanofiber layer is far from the skin, has advantages such as good mechanical properties, softness and antibacterial properties, provides certain mechanical strength, can reduce the damage and pulling of the gel layer due to external force, reduce the force transmission in the gel at the wound-fitting part, play a protective role in the wound site, and reduce the infection of the wound site by external bacteria. For slight activities at the wound site, the soft buffering, anti-adhesion and self-healing properties of the hydrogel layer can absorb the excess force and effectively avoid secondary damage to the wound surface.

[0026] 3. The quaternary ammonium salt antibacterial agent used in the present invention is grafted and blended with the nanofiber membrane substrate, endowing the membrane layer with good antibacterial properties and effectively blocking the influence of foreign bacteria on wound repair. However, due to the large amount of positive charges carried by the quaternary ammonium salt, higher requirements are put forward for the electrospinning process. In the present invention, the antibacterial nanofiber membrane is prepared by separately adjusting the spinning voltage of different substrates, controlling the electric field distribution, and the distance of the receiving roller (the spinning voltage is 10 - 20 kV, and the receiving distance is 5 - 20 cm); at the same time, a double-layer electrospun nanofiber membrane with a void gradient is obtained through the formulation of the substrate, realizing the unidirectional diversion and transfer of internal liquid to a certain extent, contributing to the effective export of excess exudate and promoting the effective healing of wounds. Description of the Drawings

[0027] Figure 1 Schematic diagram for the preparation of the antibacterial nanofiber / hydrogel composite dressing in Example 1-1.

[0028] Figure 2 Schematic diagram for the synthesis and morphology of the hydrogel in Example 1-1.

[0029] Figure 3 Schematic diagram for the morphology of nanofiber membranes with different parameters in Example 1-1. Detailed Embodiments

[0030] The following will describe the implementation schemes of the present invention in detail in combination with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0031] Example 1:

[0032] Example 1-1: This example provides an antibacterial hydrogel dressing, as Figure 1 shown, and the specific preparation steps are as follows:

[0033] Step 1: Preparation of oxidized carboxymethyl cellulose

[0034] Weigh 5 g of carboxymethyl cellulose (CMC) powder and add it to 100 mL of deionized water to prepare a 5% (w / v) aqueous solution. After complete dissolution, add 5 g of sodium periodate powder, and stir the mixed solution in the dark at room temperature. After reacting for 6 h, in order to remove the unreacted sodium periodate, add 5 mL of ethylene glycol to the mixed solution and continue stirring for 2 h. Dialyze the final product with deionized water for 5 days (the cut-off molecular weight is 14,000), change the water many times during this period, and then perform freeze-drying with a freeze dryer to obtain oxidized carboxymethyl cellulose (OCMC).

[0035] Step 2: Preparation of oxidized carboxymethyl cellulose - dopamine

[0036] Dissolve 5 g of oxidized carboxymethyl cellulose (OCMC) in 100 mL of deionized water. Add 5 g of dopamine (DA) under the protection of N₂ and react for 6 h. Dialyze the obtained product through a dialysis bag (MWCO: 8000) in deionized water for 48 h, and then freeze-dry it in a freeze dryer for three days to obtain the dopamine-oxidized carboxymethyl cellulose (OCMC-DA) product, which is sealed and stored at room temperature.

[0037] Step 3: Preparation of hydrogel

[0038] Prepare a 5% (w / v) carboxymethyl chitosan (CMCS), 10% (w / v) oxidized carboxymethyl cellulose (OCMC), and 10% (w / v) oxidized carboxymethyl cellulose-dopamine (OCMC-DA) solution. Mix them in a volume ratio of 1:1:1 and quickly stir to prepare the hydrogel. Figure 2 a shows the preparation process of the hydrogel. After the CMCS solution and the OCMC / OCMC-DA solution are blended, gelation can occur within 1 - 10 min. Figure 2 b shows the morphology of the hydrogel, which has a uniform porous structure inside.

[0039] Step 4: Preparation of antibacterial nanofiber membrane

[0040] Dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide to make a 12 wt% polyacrylonitrile solution, and dissolve polycaprolactone (PCL) and polylactic acid (PLA) in N,N-dimethylformamide to prepare a 12 wt% polycaprolactone / 4 wt% polylactic acid solution. Add 0.6% cetyl dimethyl ethyl ammonium bromide to the two solutions respectively, stir well until completely dissolved to prepare the spinning solution for the antibacterial nanofiber membrane, and finally make a double-layer composite antibacterial nanofiber membrane through the electrospinning process. The spinning parameters of the PAN layer are DC voltage: 12 kV, receiving distance: 12 cm, and feeding speed: 0.48 mL / h; the spinning parameters of the PCL / PLA layer are DC voltage: 20 kV, receiving distance: 15 cm, and feeding speed: 1 mL / h; each spinning solution is electrospun for 2 h. Figure 3 The scanning electron microscope images of the PLC / PLA (outer layer) and PAN (inner layer) antibacterial nanofiber membranes are shown respectively. The results show that PLC / PLA has finer fibers and smaller pores, while the fiber diameter of the PAN layer is thicker and the voids are significantly increased. The two-layer composite shows an obvious void gradient difference.

[0041] Step 5: Antibacterial nanofiber membrane / hydrogel composite dressing

[0042] Uniformly coat the hydrogel prepared in Step 3 on the antibacterial nanofiber membrane of Step 4 with the assistance of a homogenizer to obtain the antibacterial nanofiber / hydrogel composite dressing, and the volume of the hydrogel per unit area is 100 μL / cm 2 .

[0043] Examples 1-2:

[0044] This example is the same as Example 1-1, except that in step 3: when preparing the hydrogel, 5% (w / v) hyaluronic acid, 10% (w / v) oxidized carboxymethyl cellulose, and 10% (w / v) oxidized carboxymethyl cellulose-dopamine solution are mixed in a volume ratio of 1:1:1, and the hydrogel is prepared by rapid stirring.

[0045] Example 1-3:

[0046] This example is the same as Example 1-1, except that in step 3:

[0047] In the preparation of the hydrogel scaffold, 5% (w / v) heparin, 10% (w / v) oxidized carboxymethyl cellulose, and 10% (w / v) oxidized carboxymethyl cellulose-dopamine solution are mixed in a volume ratio of 1:1:1, and the hydrogel is prepared by rapid stirring.

[0048] Example 2:

[0049] Example 2-1:

[0050] This example is the same as Example 1-1, except that in steps 1 and 3:

[0051] Step 1: Preparation of oxidized dextran

[0052] Weigh 5 g of dextran powder and add it to 100 mL of deionized water to prepare a 5% (w / v) aqueous solution. After complete dissolution, add 5 g of sodium periodate powder, and stir the mixed solution in the dark at room temperature for 6 h. To remove the unreacted sodium periodate, add 5 mL of ethylene glycol to the mixed solution and continue stirring for 2 h. Dialyze the final product with deionized water for 5 days (cut-off molecular weight is 14,000), change the water several times during this period, and then freeze-dry it with a freeze dryer to obtain oxidized dextran.

[0053] Step 3: Preparation of hydrogel

[0054] Prepare a hydrogel by mixing 5% (w / v) carboxymethyl chitosan, 10% (w / v) oxidized dextran, and 10% (w / v) oxidized carboxymethyl cellulose-dopamine solution in a volume ratio of 1:1:1 and rapid stirring.

[0055] Example 2-2

[0056] The preparation method of this case is similar to Example 1-1, except that in steps 1 and 3:

[0057] Step 1: Preparation of oxidized sodium alginate

[0058] Weigh 5 g of dextran powder and add it to 100 mL of deionized water to prepare a 5% (w / v) aqueous solution. After complete dissolution, add 5 g of sodium periodate powder and stir the mixed solution in the dark at room temperature for 6 h. To remove the unreacted sodium periodate, add 5 mL of ethylene glycol to the mixed solution and continue stirring for 2 h. Dialyze the final product with deionized water for 5 days (cut-off molecular weight: 14,000), changing the water several times during this period, and then freeze-dry it with a freeze dryer to obtain oxidized dextran).

[0059] Step 3: Preparation of hydrogel

[0060] Prepare a hydrogel by mixing 5% (w / v) carboxymethyl chitosan, 10% (w / v) oxidized sodium alginate, and 10% (w / v) oxidized carboxymethyl cellulose-dopamine solution in a volume ratio of 1:1:1 and stirring rapidly.

[0061] Example 2-3

[0062] This example is the same as Example 1-1, except for steps 2 and 3:

[0063] Step 2: Preparation of oxidized dextran-dopamine

[0064] Dissolve 5 g of oxidized dextran in 100 mL of deionized water, add 5 g of dopamine (DA) under the protection of N2 and react for 6 h. Dialyze the obtained product in deionized water through a dialysis bag (MWCO: 8000) for 48 h, and then freeze-dry it with a freeze dryer for three days to obtain a dopamine-oxidized dextran product, which is sealed and stored at room temperature.

[0065] Step 3: Preparation of hydrogel

[0066] Prepare a hydrogel by mixing 5% (w / v) carboxymethyl chitosan, 10% (w / v) oxidized carboxymethyl cellulose, and 10% (w / v) oxidized dextran-dopamine solution in a volume ratio of 1:1:1 and stirring rapidly.

[0067] Example 2-4

[0068] This example is the same as Example 2-1, except for steps 2 and 3:

[0069] The difference lies in steps 2 and 3:

[0070] Step 2: Preparation of oxidized dextran-dopamine

[0071] Dissolve 5 g of oxidized dextran in 100 mL of deionized water. Under the protection of N2, add 5 g of dopamine (DA) and react for 6 h. Dialyze the obtained product through a dialysis bag (MWCO: 8000) in deionized water for 48 h, and then freeze-dry it in a freeze dryer for three days to obtain the dopamine-oxidized dextran product, which is sealed and stored at room temperature.

[0072] Step 3: Preparation of hydrogel

[0073] Prepare a 5% (w / v) carboxymethyl chitosan, 10% (w / v) oxidized dextran, and 10% (w / v) oxidized dextran-dopamine solution, and mix them in a volume ratio of 1:1:1. Stir rapidly to prepare the hydrogel.

[0074] Example 3:

[0075] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in Step 1:

[0076] Step 1: Preparation of oxidized carboxymethyl cellulose

[0077] Weigh 5 g of carboxymethyl cellulose powder and add it to 100 mL of deionized water to prepare a 5% (w / v) aqueous solution. After complete dissolution, add 5 g of hydrogen peroxide, and stir the mixed solution in the dark at room temperature for 6 h. To remove the unreacted sodium periodate, add 5 mL of ethylene glycol to the mixed solution and continue stirring for 2 h. Dialyze the final product with deionized water for 5 days (cut-off molecular weight is 14000), change the water several times during this period, and then freeze-dry it with a freeze dryer to obtain oxidized carboxymethyl cellulose.

[0078] Example 4-1:

[0079] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in Step 4, the antibacterial agent is replaced with dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride.

[0080] Example 4-2:

[0081] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in Step 4:

[0082] Dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide to make a 12 wt% polyacrylonitrile solution, and dissolve polycaprolactone and polylactic acid in N,N-dimethylformamide to prepare a 12 wt% polycaprolactone (PLC) / 4 wt% polylactic acid (PLA) solution; a double-layer composite antibacterial nanofiber membrane is made by the electrospinning process. The spinning parameters of the PAN layer are: DC voltage: 12 kV, receiving distance: 12 cm, advancing speed: 0.48 mL / h; the spinning parameters of the PCL / PLA layer are: DC voltage: 20 kV, receiving distance: 15 cm, advancing speed: 1 mL / h; each spinning solution is spun for 2 h.

[0083] Example 5-1

[0084] The preparation method of the dressing in this example is similar to that of Example 1-1, the difference lies in step 4:

[0085] Step 4: Preparation of the antibacterial nanofiber membrane

[0086] Dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide to make a 12 wt% polyacrylonitrile solution, and dissolve polycaprolactone in N,N-dimethylformamide to prepare a 16 wt% polycaprolactone (PLC) solution; add 0.6% cetyl dimethyl ethyl ammonium bromide respectively, stir well until completely dissolved to make two spinning solutions, and finally make a double-layer composite antibacterial nanofiber membrane by the electrospinning process. The spinning parameters of the PAN layer are: DC voltage: 12 kV, receiving distance: 12 cm, advancing speed: 0.48 mL / h; the spinning parameters of the PCL / PLA layer are: DC voltage: 20 kV, receiving distance: 15 cm, advancing speed: 1 mL / h; each spinning solution is spun for 2 h.

[0087] Example 5-2

[0088] The preparation method of the composite dressing in this example is similar to that of Example 1-1, the difference lies in step 4:

[0089] Step 4: Preparation of the antibacterial nanofiber membrane

[0090] Dissolve polyacrylonitrile (PAN) and polylactic acid (PLA) in N,N-dimethylformamide to make an 8 wt% polyacrylonitrile / 4 wt% polylactic acid mixed solution, and dissolve polycaprolactone and polylactic acid in N,N-dimethylformamide to prepare a 12 wt% polycaprolactone (PLC) / 4 wt% polylactic acid (PLA) solution; add 0.6% cetyl dimethyl ethyl ammonium bromide to the two solutions respectively, stir well until completely dissolved to prepare a spinning solution for antibacterial nanofiber membranes, and finally make a double-layer composite antibacterial nanofiber membrane through the electrospinning process. The spinning parameters of the PAN layer are DC voltage: 12 kV, receiving distance: 12 cm, and advancing speed: 0.48 mL / h; the spinning parameters of the PCL / PLA layer are DC voltage: 20 kV, receiving distance: 15 cm, and advancing speed: 1 mL / h; each spinning solution is spun for 2 h. Example 5-3

[0091] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in step 4:

[0092] Step 4: Preparation of antibacterial nanofiber membrane

[0093] Dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide solution to make a 12 wt% polyacrylonitrile solution, add 0.6% cetyl dimethyl ethyl ammonium bromide, stir well until completely dissolved, and finally make a single-layer composite antibacterial nanofiber membrane through the electrospinning process. The electrospinning parameters are DC voltage: 12 kV, receiving distance: 12 cm, advancing speed: 0.48 mL / h, and spinning time is 4 h.

[0094] Example 5-4

[0095] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in step 4:

[0096] Step 4: Preparation of antibacterial nanofiber membrane

[0097] Dissolve polycaprolactone and polylactic acid in N,N-dimethylformamide to prepare a 12 wt% polycaprolactone / 4 wt% polylactic acid mixed solution, add 0.6% cetyl dimethyl ethyl ammonium bromide, stir well until completely dissolved, and finally make a single-layer antibacterial nanofiber membrane through the electrospinning process. The electrospinning parameters are DC voltage: 20 kV, receiving distance: 15 cm, advancing speed: 1 mL / h, and spinning time is 4 h.

[0098] Example 6

[0099] The preparation method of the dressing in this example is similar to that of Example 1-1, except that in step 3:

[0100] Prepare a 5% (w / v) carboxymethyl chitosan solution and a 10% (w / v) oxidized carboxymethyl cellulose-dopamine solution, mix them in a volume ratio of 1:1, and rapidly stir to prepare a hydrogel.

[0101] Example 7

[0102] The preparation method of the dressing in this example is similar to that of Examples 1-1, except that in step 3:

[0103] Prepare a 5% (w / v) carboxymethyl chitosan solution and a 10% (w / v) oxidized carboxymethyl cellulose solution, mix them in a volume ratio of 1:1, and rapidly stir to prepare a hydrogel.

[0104] Example 8

[0105] The preparation method of the dressing in this example is similar to that of Examples 1-1, except that in step 5:

[0106] The hydrogel prepared in step 3 is evenly coated on the antibacterial nanofiber membrane in step 4 with the assistance of a homogenizer to obtain an antibacterial nanofiber / hydrogel composite dressing, and the volume of the hydrogel per unit area is 50 μL / cm 2 .

[0107] Example 9

[0108] The preparation method of the dressing in this example is similar to that of Examples 1-1, except that in step 5:

[0109] The hydrogel prepared in step 3 is evenly coated on the antibacterial nanofiber membrane in step 4 with the assistance of a homogenizer to obtain an antibacterial nanofiber / hydrogel composite dressing, and the volume of the hydrogel per unit area is 150 μL / cm 2 .

[0110] The dressings obtained in the above examples and comparative examples were respectively subjected to performance tests:

[0111] 1. Surface morphology characterization of the antibacterial nanofiber membrane:

[0112] The surface morphological structure of the antibacterial nanofiber membrane was characterized using a field emission scanning electron microscope (S-4800). The dried sample was fixed on the electron microscope stage using conductive glue, and the sample morphology was observed after sputtering with gold. The Image J software was used to estimate the pore size and void distribution of the nanofiber membrane sample and calculate the average value. The specific data are shown in the following table.

[0113] In theory, the directional movement of liquid in the capillary channels can be achieved by changing the pore structure or surface properties. According to the Laplace equation, the capillary force can be enhanced with the narrowing of pores and a higher degree of wettability, driving the movement of water in the capillary pores and causing the liquid in the porous material with a gradient pore size change to transfer from the large pores to the small pores. The diameter and pore size data of the antibacterial electrospun membrane in the above examples are specifically shown in Table 1. Among them, the inner and outer layer fiber diameters and pore size results in Examples 1, 2, 3, 4-1, 6, 7, 8, and 9 are equivalent to those in Example 1-1, so only the data of Example 1-1 are listed.

[0114] Table 1

[0115]

[0116]

[0117] 2. Mechanical property test of hydrogel

[0118] The mechanical properties of the hydrogel were tested using a universal testing machine. Hydrogel cylinders with uniform shape and size were prepared through a mold, with a compression speed of 1 mm / min and a compression strain of 60%. The mechanical property data of the hydrogel layer in the preparation process of the above examples are specifically shown in Table 2. In addition, the mechanical properties of the hydrogels in Examples 4, 5, 8, and 9 are the same as those in Example 1-1, so only the data of Example 1-1 are listed.

[0119] Table 2

[0120]

[0121] 3. Antibacterial test:

[0122] The antibacterial test refers to "GB / T 20944.1-2007 Textiles - Evaluation of antibacterial properties - Part 1: Agar plate diffusion method", "GB / T 20944.2-2007 Textiles - Evaluation of antibacterial properties - Part 2: Absorption method" and "GB / T 20944.3-2008 Textiles - Evaluation of antibacterial properties - Part 3: Oscillation method"

[0123] Using the plate diffusion method, the antibacterial rates of various bacteria of the dressing samples obtained in the examples were estimated. The specific method is as follows: Dilute the bacterial liquid to a bacterial concentration of 1×10 5cfu / mL, and then place the disinfected sample into the diluted bacterial suspension. Shake the bacterial suspensions containing different hydrogel samples in a constant temperature shaker at 150 rpm at 37 °C for 24 h. After culturing for 24 h, spread the bacterial suspensions diluted to different concentrations onto agar plates. After culturing for 18 - 24 h (at a temperature of 37 °C), visible colonies can be formed on the agar plates. Set the original bacterial solution without the dressing sample as the control group. The antibacterial rate can be quantitatively estimated by counting the colonies. The antibacterial performance of the sample can be characterized by the logarithm of colony reduction and the antibacterial rate, and the specific calculation method is shown in the following formula.

[0124]

[0125] The specific antibacterial data obtained from the above examples are shown in Table 3. Among them, the effects in Examples 2, 3, and 5 - 9 are equivalent to those in Example 1 - 1, all above 99.5%, without significant differences. Therefore, only the antibacterial rates of Example 1 - 1 are listed. In addition, carboxymethyl chitosan also has a certain antibacterial effect.

[0126] Table 3

[0127] Group Bacteriostatic rate / % Example 1-1 99.8 Example 1-2 95.5 Example 1-3 95.6 Example 4-1 99.1 Example 4-2 20.3

[0128] Note:

[0129] 4. In vivo wound healing test

[0130] Evaluate the effect of the hydrogel sample on wound healing through a mouse diabetic wound healing model. All mice were intraperitoneally injected with STZ (streptozotocin) solution at a dose of 70 mg / kg before the experiment to induce diabetes. Mice with BGL (blood glucose level) maintained above 300 mg / dL for 6 consecutive days were rated as diabetic mice. Mice with successful diabetes induction can proceed to the next stage of the full-thickness defect model experiment. Before the experiment, first anesthetize the mice, and then use an animal electric shaver to remove the hair on the back of the mice. Disinfect the surgical area on the back of the mice with a 75% alcohol solution, and then create a circular wound with a diameter of about 7 mm on the back of each mouse. Subsequently, drop the pre-prepared hydrogel precursor mixed solution onto the wound site so that the in-situ crosslinked hydrogel can cover the entire wound. At the same time, use the wound treated with medical gauze as the control group. Use Image J software to measure and calculate the area of each wound (the wound area is A t ) treated with different hydrogel samples at 0, 3, 5, 7, and 14 d. The initial wound area is A o . The calculation formula for the wound area is shown in the following table.

[0131]

[0132] Table 4

[0133] Group Wound healing rate after 14d / % Example 1-1 95.83 Example 1-2 90.78 Example 1-3 90.45 Example 2-1 94.62 Example 2-2 94.12 Example 2-3 94.51 Example 2-4 94.21 Example 3 94.02 Example 4-1 94.73 Example 4-2 85.70 Example 5-1 94.15 Example 5-2 94.56 Example 5-3 91.79 Example 5-4 91.81 Example 6 92.99 Example 7 93.01 Example 8 95.02 Example 9 95.75

[0134] Chronic wounds, clinically, generally refer to wounds formed for various reasons that have not healed after more than 1 month of treatment and show no tendency to heal. The limitation of "1 month" is not absolute. It results from various factors such as wound size, etiology, and the general health status of the individual. Therefore, it cannot be simply divided by time limit. Chronic wounds are generally divided into 5 common types: venous ulcers, arterial ulcers, diabetic ulcers, traumatic ulcers, and pressure ulcers. There are also other wounds caused by tumors and connective tissue diseases such as leprosy. The application conditions of chronic wounds in conventional wounds are the most demanding and are also a major problem restricting clinical development. Their treatment methods require new requirements based on general wound care. The present invention selects chronic wounds for experiments, and the effect is good, and it is also applicable to other conventional wounds.

[0135] The specific application field of the present invention is only a preferred embodiment of the present invention, but the application scope of the present invention is not limited thereto. The above embodiments are only for illustrating the technical ideas and features of the present invention. The content described is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Within the technical scope disclosed by the present invention, equivalent changes or improvements made according to the technical solution and inventive concept of the present invention should all be covered within the protection scope of the present invention.

Claims

1. An antibacterial hydrogel dressing for the treatment of infectious chronic wounds, characterized in that: This dressing is made by directly coating a hydrogel on an antibacterial nanofiber membrane layer; the hydrogel is prepared from oxidized polysaccharide, dopamine-modified oxidized polysaccharide, and carboxymethyl chitosan through Schiff base reaction, where the oxidized polysaccharide is one or more of oxidized carboxymethyl cellulose, oxidized dextran, and oxidized sodium alginate; the dopamine-modified oxidized polysaccharide is one or more of dopamine-modified oxidized carboxymethyl cellulose, dopamine-modified oxidized dextran, and dopamine-modified oxidized sodium alginate; the antibacterial nanofiber membrane layer is prepared by blending a quaternary ammonium salt antibacterial agent with a nanofiber membrane substrate and then through electrospinning process; the antibacterial nanofiber membrane layer is at least a bilayer structure, the spinning void size of the fiber membrane layer close to the hydrogel side is larger than that of the fiber membrane layer far from the hydrogel side, and the nanofiber membrane substrate in the fiber membrane layer close to the hydrogel side is polyacrylonitrile, and the nanofiber membrane substrate in the fiber membrane layer far from the hydrogel side contains polycaprolactone and polylactic acid, and the mass ratio of the two is 2 - 5:

1.

2. The dressing according to claim 1, wherein: The thickness of the antibacterial nanofiber membrane layer is 0.5 - 2 mm; the coating amount of the hydrogel is 10 - 200 μL / cm 2 .

3. The dressing according to claim 1, characterized in that: The mass ratio of oxidized polysaccharide, dopamine-modified oxidized polysaccharide, and carboxymethyl chitosan is 1 - 2:1 - 2:0.5 - 1.

4. The dressing according to any one of claims 1 to 3, characterized in that: The quaternary ammonium salt antibacterial agent is one or more of cetyl dimethyl ethyl ammonium bromide, dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride, and dimethylhexadecyl [3-(trimethoxysilyl)propyl] ammonium chloride.

5. The preparation method of the dressing according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1. Prepare aqueous solutions of oxidized polysaccharide, dopamine-modified oxidized polysaccharide, and carboxymethyl chitosan respectively, mix them evenly in proportion, and then react for 1 - 10 min under the condition of 20 - 37 °C to obtain the hydrogel. S2. Blend and graft the quaternary ammonium salt antibacterial agent with the nanofiber membrane substrate, add a solvent to prepare a spinning solution, and obtain an antibacterial nanofiber membrane through electrospinning. S3. Coat the hydrogel obtained in S1 on the antibacterial nanofiber membrane obtained in S2 to obtain the antibacterial hydrogel dressing for the treatment of infectious chronic wounds.

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