Preparation method of flexible dressing for treating chronic ulcer wounds by compensating for damaging current

Abstract

The invention discloses a method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damage current. The method is characterized in that methacryloyl hyaluronic acid is first prepared and freeze-dried for standby use; then methacryloyl hyaluronic acid coupled with dopamine is prepared; then AgNO3 solution is added to the methacryloyl hyaluronic acid solution, and methacryloyl hyaluronic acid-dopamine hydrogel containing Ag nanoparticles is obtained by ultraviolet irradiation, i.e., conductive antibacterial hydrogel; then a silver-copper wire microcircuit flexible patch is prepared; finally, the conductive antibacterial hydrogel is coated on the flexible patch, and a wire is led out on the silver-copper wire microcircuit, and a power source is connected to obtain a flexible dressing for compensating for damage current; the method has the advantages that the flexible dressing is uniformly conductive, has good conductive performance, and is closely attached to the wound surface, so that the performance of the dressing including water retention, uniform electric field, antibacterial, cell growth promotion, etc., acts positively on the wound, thereby promoting rapid and perfect repair of the wound surface.

Description

Technical Field

[0001] The invention relates to the preparation of medical wound dressings, in particular to a method for preparing a flexible dressing for treating chronic ulcer wounds and used for compensating for damaging current. Background Art

[0002] Trauma caused by natural disasters, sudden accidents and immune diseases is one of the most common diseases in clinical practice. The incidence of chronic ulcer wounds represented by diabetic ulcers and lower extremity venous ulcers is also increasing year by year. Chronic diabetic ulcers are typical chronic non-healing wounds, which are a common disease worldwide and a serious threat to human health.

[0003] The structure of human skin includes the epidermis, dermis and subcutaneous tissue, among which the epidermis is divided into the stratum corneum, the clear layer, the granular layer, the spinous cell layer and the basal layer. Normal skin has an endogenous potential across the epidermis, like a battery with a potential difference of 10 to 60 mV, and the potential on the basal side is always higher than that on the apical side. After skin injury, the positive charge on the basal side of the epidermis at the wound surface is lost, forming a potential difference with the basement membrane of the surrounding normal skin, forming an "injury current". However, for chronic ulcer wounds caused by diabetes, the duration and peak value of the injury current are significantly lower than those of non-ulcer wounds. The weakening of the injury current is an important reason for hindering the healing of chronic ulcer wounds. Supplementing the "injury current" through exogenous electrical stimulation is one of the important strategies for treating such wounds. Exogenous electrical stimulation includes electrode attachment, electrode implantation, electroacupuncture therapy and other methods. However, traditional electrode patches are hard electronic devices made of dry, rigid or chemically inert materials. Not only do they not fit well with the skin, resulting in discontinuity of the electrodes and thus failure to form a complete stimulation electric field, but the biocompatibility of the material itself is also poor, which is extremely detrimental to wound healing. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current. The prepared flexible dressing has good electrical conductivity, good compensation effect on wound damaging current, and excellent biocompatibility, which is beneficial to promoting wound healing.

[0005] The technical solution adopted by the present invention to solve the above technical problem is: a method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current, comprising the following specific steps:

[0006] (1) In a weakly alkaline environment, methacrylic anhydride is reacted with a high molecular weight hyaluronic acid solution with a concentration of 0.5-2wt% for 24 hours, wherein the mass ratio of methacrylic anhydride to hyaluronic acid is 1:1-1:5, and then dialyzed for 2 days using a dialysis bag with a molecular weight cutoff of 8000-14000Da to obtain methacrylylated hyaluronic acid, which is freeze-dried for later use;

[0007] (2) In a weakly acidic environment and under nitrogen protection, the methacryloyl hyaluronic acid obtained in step (1) is dissolved in water to obtain an aqueous solution with a concentration of 10 to 50 mg / mL, a coupling agent is added and stirred evenly, wherein the mass ratio of the methacryloyl hyaluronic acid to the coupling agent is 0.5 to 2.0, dopamine is then added, and the mass ratio of dopamine to the methacryloyl hyaluronic acid is 1 to 1.5, and the mixture is reacted at room temperature for 12 to 24 hours, and then dialyzed for 3 days using a dialysis bag with a molecular weight cutoff of 8000 to 14000 Da to obtain methacryloyl hyaluronic acid coupled with dopamine;

[0008] (3) dissolving the dopamine-coupled methacryloyl hyaluronic acid obtained in step (2) in phosphate buffer (PBS) to obtain a mixed solution with a methacryloyl hyaluronic acid concentration of 2 wt%, then adding a photoinitiator to the mixed solution to control the concentration of the photoinitiator in the mixed solution to be 0.1-2 wt%, and adding AgNO3 solution to the mixed solution to control the concentration of AgNO3 in the mixed solution to be 1-2 mg / mL, and irradiating with ultraviolet light for 1 min to obtain a methacryloyl hyaluronic acid-dopamine hydrogel containing Ag nanoparticles, i.e., a conductive antibacterial hydrogel;

[0009] (4) preparing uniformly distributed microgrooves on a flexible substrate, and filling the microgrooves with a silver nanoparticle suspension, sintering the silver nanoparticles to form silver wires, and then electroplating copper on the surface of the silver wires in the microgrooves to form a silver-copper wire microcircuit flexible patch;

[0010] (5) The conductive antibacterial hydrogel prepared in step (3) is coated on the flexible patch obtained in step (4) to form a hydrogel-like flexible skin patch with good antibacterial properties, and a wire is led out from the silver-copper wire microcircuit and connected to a power supply with a weak current of 1 to 100 mA to obtain a flexible dressing for compensating for the damage current.

[0011] Furthermore, in the step (1), the molecular weight of the high molecular weight hyaluronic acid is 200-400 kDa, and the pH value of the weak alkaline environment is 8.5-10.

[0012] Furthermore, the coupling agent used in step (2) is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a molar ratio of 1:1, and the pH value of the weak acid environment is 5.0-6.0.

[0013] Furthermore, the photoinitiator used is photoinitiator I2959, the wavelength of ultraviolet light is 365nm, and the light irradiance is 300mW / cm 2 .

[0014] Furthermore, the microgrooves are composed of a plurality of polygons arranged in an array and connected to each other.

[0015] Furthermore, in the step (4), the sintering temperature of the silver nanoparticles is 140-180°C.

[0016] Furthermore, the material of the flexible substrate is a PET sheet or a PDMS sheet.

[0017] Compared with the prior art, the advantages of the present invention are that the silver-copper wire microcircuit is evenly distributed, and the conductive antibacterial hydrogel is coated on the microcircuit flexible patch, so that the entire flexible dressing is evenly conductive and has good conductive properties. The flexible dressing is not limited by factors such as the shape and depth of the wound surface when used, and is closely attached to the wound surface, so that the properties of the dressing, including water retention, uniform electric field, antibacterial, and cell growth promotion, act positively on the wound, thereby promoting the rapid and perfect repair of the wound surface. In addition, after the power is turned on, the microcurrent on the flexible dressing can compensate for the damage current of the chronic ulcer wound surface, so that the chronic ulcer wound surface can also be repaired quickly and efficiently, and the chronic ulcer wound surface is currently a stubborn disease that is difficult to cure clinically. In short, this flexible dressing contains a conductive antibacterial hydrogel, which, under the premise of protecting the wound surface from microbial invasion, provides the cells at the wound with a moist microenvironment for proliferation, regeneration and tissue reconstruction, and even the wound surface with irregular morphology and uneven depth can achieve the effect of perfect repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of microgrooves on a flexible substrate of the present invention;

[0019] Figure 2 This is a comparison chart of the wound recovery effects of three different treatment methods on mice;

[0020] Figure 3 The following are pathological sections of the three different treatment methods at 23 days. Implementation

[0021] The present invention is further described in detail below with reference to the accompanying drawings.

[0022] Embodiment 1: A method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current, comprising the following specific steps:

[0023] (1) In a weakly alkaline environment with a pH value of 8.5, methacrylic anhydride is reacted with a hyaluronic acid solution with a concentration of 2wt% and a molecular weight of 200-400kDa for 24 hours, wherein the mass ratio of methacrylic anhydride to hyaluronic acid is 1:1, and then dialyzed for 2 days using a dialysis bag with a molecular weight cutoff of 10000Da to obtain methacrylylated hyaluronic acid, which is lyophilized for later use;

[0024] (2) In a weak acid environment with a pH value of 6.0 and under nitrogen protection, the methacryloyl hyaluronic acid obtained in step (1) is dissolved in water to obtain an aqueous solution with a concentration of 15 mg / mL, a coupling agent is added and stirred evenly, wherein the coupling agent is obtained by mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1, wherein the mass ratio of methacryloyl hyaluronic acid to the coupling agent is 0.8, and then dopamine is added, and the mass ratio of dopamine to methacryloyl hyaluronic acid is 1, and the reaction is carried out at room temperature for 12 hours, and then dialyzed for 3 days using a dialysis bag with a molecular weight cutoff of 10,000 Da to obtain methacryloyl hyaluronic acid coupled with dopamine;

[0025] (3) Dissolve the dopamine-coupled methacryloyl hyaluronic acid obtained in step (2) in phosphate buffer (PBS) to obtain a mixed solution with a concentration of 2 wt% of methacryloyl hyaluronic acid, then add photoinitiator I2959 to the mixed solution, and control the concentration of the photoinitiator in the mixed solution to be 0.5 wt%. At the same time, add AgNO3 solution to the mixed solution, and control the concentration of AgNO3 in the mixed solution to be 1 mg / mL. Irradiate with ultraviolet light with a wavelength of 365 nm for 1 min, and the light irradiance is 300 mW / cm 2 , obtaining a methacrylylated hyaluronic acid-dopamine hydrogel containing Ag nanoparticles, namely, a conductive antibacterial hydrogel;

[0026] (4) preparing uniformly distributed microgrooves on a flexible substrate, and filling the microgrooves with a silver nanoparticle suspension, sintering the silver nanoparticles to form silver wires at a sintering temperature of 140°C, and then electroplating copper on the surface of the silver wires in the microgrooves to form a silver-copper wire microcircuit flexible patch;

[0027] (5) The conductive antibacterial hydrogel prepared in step (3) is coated on the flexible patch obtained in step (4) to form a hydrogel-like flexible skin patch with good antibacterial properties, and a wire is led out from the silver-copper wire microcircuit and connected to a power supply with a weak current of 1 to 100 mA to obtain a flexible dressing for compensating for the damage current.

[0028] Embodiment 2: A method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current, comprising the following specific steps:

[0029] (1) In a weakly alkaline environment with a pH value of 9, methacrylic anhydride is reacted with a hyaluronic acid solution with a concentration of 1wt% and a molecular weight of 200-400kDa for 24 hours, wherein the mass ratio of methacrylic anhydride to hyaluronic acid is 1:3, and then dialyzed for 2 days using a dialysis bag with a molecular weight cutoff of 12000Da to obtain methacrylylated hyaluronic acid, which is freeze-dried for later use;

[0030] (2) In a weak acid environment with a pH value of 5.5 and under nitrogen protection, the methacryloyl hyaluronic acid obtained in step (1) was dissolved in water to obtain an aqueous solution with a concentration of 30 mg / mL, and a coupling agent was added and stirred evenly. The coupling agent was obtained by mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1, wherein the mass ratio of methacryloyl hyaluronic acid to the coupling agent was 1.2, and then dopamine was added, and the mass ratio of dopamine to methacryloyl hyaluronic acid was 1.3. The mixture was reacted at room temperature for 24 hours, and then dialyzed for 3 days using a dialysis bag with a molecular weight cutoff of 12000Da to obtain methacryloyl hyaluronic acid coupled with dopamine;

[0031] (3) Dissolve the dopamine-coupled methacryloyl hyaluronic acid obtained in step (2) in phosphate buffer (PBS) to obtain a mixed solution with a concentration of 2 wt% of methacryloyl hyaluronic acid, then add photoinitiator I2959 to the mixed solution to control the concentration of the photoinitiator in the mixed solution to 1 wt%, and simultaneously add AgNO3 solution to the mixed solution to control the concentration of AgNO3 in the mixed solution to 1.5 mg / mL, and irradiate with ultraviolet light of a wavelength of 365 nm for 1 min, with a light irradiance of 300 mW / cm 2 , obtaining a methacrylylated hyaluronic acid-dopamine hydrogel containing Ag nanoparticles, namely, a conductive antibacterial hydrogel;

[0032] (4) preparing uniformly distributed microgrooves on a flexible substrate, and filling the microgrooves with a silver nanoparticle suspension, sintering the silver nanoparticles to form silver wires at a sintering temperature of 160°C, and then electroplating copper on the surface of the silver wires in the microgrooves to form a silver-copper wire microcircuit flexible patch;

[0033] (5) The conductive antibacterial hydrogel prepared in step (3) is coated on the flexible patch obtained in step (4) to form a hydrogel-like flexible skin patch with good antibacterial properties, and a wire is led out from the silver-copper wire microcircuit and connected to a power supply with a weak current of 1 to 100 mA to obtain a flexible dressing for compensating for the damage current.

[0034] Embodiment 3: A method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current, comprising the following specific steps:

[0035] (1) In a weakly alkaline environment with a pH value of 10, methacrylic anhydride is reacted with a hyaluronic acid solution with a concentration of 0.5wt% and a molecular weight of 200-400kDa for 24 hours, wherein the mass ratio of methacrylic anhydride to hyaluronic acid is 1:5, and then dialyzed for 2 days using a dialysis bag with a molecular weight cutoff of 14000Da to obtain methacrylylated hyaluronic acid, which is lyophilized for later use;

[0036] (2) In a weak acid environment with a pH value of 5.0 and under nitrogen protection, the methacryloyl hyaluronic acid obtained in step (1) is dissolved in water to obtain an aqueous solution with a concentration of 50 mg / mL, a coupling agent is added and stirred evenly, wherein the coupling agent is obtained by mixing 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in a molar ratio of 1:1, wherein the mass ratio of methacryloyl hyaluronic acid to the coupling agent is 2.0, and then dopamine is added, and the mass ratio of dopamine to methacryloyl hyaluronic acid is 1.5. The mixture is reacted at room temperature for 24 hours, and then dialyzed for 3 days using a dialysis bag with a molecular weight cutoff of 14,000 Da to obtain methacryloyl hyaluronic acid coupled with dopamine;

[0037] (3) Dissolve the dopamine-coupled methacryloyl hyaluronic acid obtained in step (2) in phosphate buffer (PBS) to obtain a mixed solution with a concentration of 2 wt% of methacryloyl hyaluronic acid, then add photoinitiator I2959 to the mixed solution to control the concentration of the photoinitiator in the mixed solution to 2 wt%, and simultaneously add AgNO3 solution to the mixed solution to control the concentration of AgNO3 in the mixed solution to 2 mg / mL, and irradiate with ultraviolet light with a wavelength of 365 nm for 1 min, with a light irradiance of 300 mW / cm 2 , obtaining a methacrylylated hyaluronic acid-dopamine hydrogel containing Ag nanoparticles, namely, a conductive antibacterial hydrogel;

[0038] (4) preparing uniformly distributed microgrooves on a flexible substrate, and filling the microgrooves with a silver nanoparticle suspension, sintering the silver nanoparticles to form silver wires at a sintering temperature of 180°C, and then electroplating copper on the surface of the silver wires in the microgrooves to form a silver-copper wire microcircuit flexible patch;

[0039] (5) The conductive antibacterial hydrogel prepared in step (3) is coated on the flexible patch obtained in step (4) to form a hydrogel-like flexible skin patch with good antibacterial properties, and a wire is led out from the silver-copper wire microcircuit and connected to a power supply with a weak current of 1 to 100 mA to obtain a flexible dressing for compensating for the damage current.

[0040] In the above embodiment, the microgrooves on the flexible substrate are composed of a plurality of polygons arranged in an array and connected to each other. The polygons may be hexagons, pentagons or quadrilaterals, for example. Figure 1 As shown; in addition, the material of the flexible substrate can be a PET sheet or a PDMS (polydimethylsiloxane) sheet, or other non-toxic flexible sheet materials.

[0041] The flexible dressing prepared by the present invention was used to repair full-thickness skin defects in diabetic mice to verify the effect, specifically:

[0042] First, multiple diabetic mice were constructed by using drugs or high-sugar feeding, and then the diabetic mice were anesthetized one by one, the hair on the back was shaved and disinfected, and then a full-thickness skin defect wound was constructed on the back of each mouse with surgical scissors. The wound shape was round or square, and Staphylococcus aureus, which is most easily infected in clinical chronic wounds, was added to the wound to simulate chronic ulcerative wounds. Then, the flexible dressing of the present invention, the traditional electrode patch and the conventional gauze were respectively covered on the defect wound of each mouse to compare the effects. The flexible dressing and the electrode patch were continuously powered for 1 to 3 hours every day, and the weak current was controlled to be 0.5 to 100 mA. The mice using the flexible dressing of the present invention had wounds healed after 28 days, while the wounds of the mice covered only with gauze and not treated were still large, and the mice using the electrode patch were second. See the attached for details. Figure 2 Comparison photos of the effects and pathological sections at 23 days.

[0043] The protection scope of the present invention includes but is not limited to the above embodiments, and its protection scope is subject to the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by technicians in this field shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a flexible dressing for treating chronic ulcer wounds for compensating for damaging current, characterized in that The specific steps include: (1) In a weakly alkaline environment, methacrylic anhydride is reacted with a high molecular weight hyaluronic acid solution with a concentration of 0.5-2wt% for 24 hours, wherein the mass ratio of methacrylic anhydride to hyaluronic acid is 1:1-1:5, and then dialyzed for 2 days using a dialysis bag with a molecular weight cutoff of 8000-14000Da to obtain methacrylylated hyaluronic acid, which is freeze-dried for later use; (2) In a weakly acidic environment and under nitrogen protection, the methacryloyl hyaluronic acid obtained in step (1) is dissolved in water to obtain an aqueous solution with a concentration of 10 to 50 mg / mL, a coupling agent is added and stirred evenly, wherein the mass ratio of the methacryloyl hyaluronic acid to the coupling agent is 0.5 to 2.0, dopamine is then added, and the mass ratio of dopamine to the methacryloyl hyaluronic acid is 1 to 1.5, and the mixture is reacted at room temperature for 12 to 24 hours, and then dialyzed for 3 days using a dialysis bag with a molecular weight cutoff of 8000 to 14000 Da to obtain methacryloyl hyaluronic acid coupled with dopamine; (3) dissolving the dopamine-coupled methacryloyl hyaluronic acid obtained in step (2) in phosphate buffer (PBS) to obtain a mixed solution with a methacryloyl hyaluronic acid concentration of 2 wt%, then adding a photoinitiator to the mixed solution to control the concentration of the photoinitiator in the mixed solution to be 0.1-2 wt%, and adding AgNO3 solution to the mixed solution to control the concentration of AgNO3 in the mixed solution to be 1-2 mg / mL, and irradiating with ultraviolet light for 1 min to obtain a methacryloyl hyaluronic acid-dopamine hydrogel containing Ag nanoparticles, i.e., a conductive antibacterial hydrogel; (4) preparing uniformly distributed microgrooves on a flexible substrate, and filling the microgrooves with a silver nanoparticle suspension, sintering the silver nanoparticles to form silver wires, and then electroplating copper on the surface of the silver wires in the microgrooves to form a silver-copper wire microcircuit flexible patch; (5) The conductive antibacterial hydrogel prepared in step (3) is coated on the flexible patch obtained in step (4) to form a hydrogel-like flexible skin patch with good antibacterial properties, and a wire is led out from the silver-copper wire microcircuit and connected to a power supply with a weak current of 1 to 100 mA to obtain a flexible dressing for compensating for the damage current.

2. The method for preparing the flexible dressing according to claim 1, characterized in that: In the step (1), the molecular weight of the high molecular weight hyaluronic acid is 200-400 kDa, and the pH value of the weak alkaline environment is 8.5-10.

3. The method for preparing the flexible dressing according to claim 1, characterized in that: The coupling agent used in step (2) is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a molar ratio of 1:1, and the pH value of the weak acid environment is 5.0-6.

0.

4. The method for preparing the flexible dressing according to claim 1, characterized in that: The photoinitiator used is photoinitiator I2959, the wavelength of ultraviolet light is 365nm, and the light irradiance is 300mW / cm 2 .

5. The method for preparing the flexible dressing according to claim 1, characterized in that: The microgrooves are composed of a plurality of polygons arranged in an array and connected to each other.

6. The method for preparing the flexible dressing according to claim 1, characterized in that: In the step (4), the sintering temperature of the silver nanoparticles is 140-180°C.

7. The method for preparing the flexible dressing according to claim 1, characterized in that: The material of the flexible substrate is a PET sheet or a PDMS sheet.

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