A diabetic foot external dressing and preparation method thereof

Abstract

The present invention belongs to the field of topical biological preparations, and specifically relates to a diabetic foot topical dressing and a preparation method thereof. The composition of the topical dressing includes a hydrogel matrix and a liposome; the composition of the hydrogel matrix includes the following components: polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, honey, lactic acid, collagen and glycerol; the composition of the liposome includes the following components: polyvinyl alcohol, phosphatidylcholine, polyvinyl pyrrolidone, nanosilver particles, CeO2 nanozymes, vitamin E and active extracts. The present invention uses lactic acid to regulate the pH of the wound surface, so that CeO2 nanozymes and various active ingredients can play a role in the optimal environment, and the comprehensive performance of moisturizing, antibacterial and promoting tissue regeneration provided by the hydrogel constructed by polyacrylic acid, chitosan and hyaluronic acid, cooperates with CeO2 nanozymes, various plant extracts and nutrients to effectively inhibit bacteria and promote wound healing.

Description

Technical Field

[0001] The invention belongs to the field of external biological preparations, and particularly relates to an external dressing for diabetic foot and a preparation method thereof. Background Art

[0002] Diabetic foot is one of the common complications of diabetic patients, mainly manifested as foot infection, ulcer, gangrene, etc., which may lead to amputation in severe cases. The occurrence of diabetic foot is closely related to many factors, including diabetic neuropathy, vascular disease, immunodeficiency, trauma and infection. The wound healing ability of diabetic patients is poor, and the local microcirculation is poor, which makes the treatment of diabetic foot more complicated. The treatment of diabetic foot usually requires comprehensive intervention, especially early intervention is crucial. Therefore, the development of an external dressing that can not only promote wound healing, anti-infection, but also reduce inflammation and improve local blood circulation is of great significance for the effective treatment of diabetic foot. Traditional dressings, such as gauze and bandages, as the most common wound coverings, can absorb exudate and protect the wound from external contamination, but their absorption capacity is limited, especially in diabetic foot ulcers with high exudate, which are prone to saturation, so that the dressing needs to be changed frequently. Moreover, when changing the dressing, the new epithelial tissue may be torn, resulting in delayed wound healing. In addition, traditional dressings lack the function of regulating the wound microenvironment, which is not conducive to the continuous healing of the wound.

[0003] At present, there are some new types of diabetic foot dressings on the market. For example, transparent dressings can effectively cover the wound surface and maintain a local moist environment to promote wound healing. Its high transparency makes it easy to observe the wound surface. However, transparent dressings usually lack antibacterial function and deep penetration, and their effect is relatively limited for deeper ulcers or infected wounds in patients with diabetic foot. Another type of dressing is silver ion dressing. Silver ions have good antibacterial effects, can effectively reduce infection, and promote wound healing, so they are widely used in the treatment of diabetic foot. However, during long-term use, silver ion dressings may cause silver ion deposition, irritate the skin, and even cause allergic reactions, affecting their efficacy and safety. Therefore, based on the shortcomings of traditional dressings and the limitations of existing technologies, it is particularly necessary to develop a diabetic foot dressing that can be used for a long time and has strong antibacterial function and deep penetration effect. Summary of the invention

[0004] In view of the defects of the prior art, the object of the present invention is to provide a diabetic foot external dressing and a preparation method thereof.

[0005] The technical effect described in the present invention is achieved through the following technical scheme: a diabetic foot external dressing, which comprises a hydrogel matrix and liposomes; the composition of the hydrogel matrix comprises the following ingredients in parts by weight: 80 to 100 parts of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, 12 to 18 parts of honey, 3 to 4 parts of lactic acid, 8 to 12 parts of collagen and 5 to 10 parts of glycerol; the composition of the liposomes comprises the following ingredients in parts by weight: 5 to 8 parts of polyvinyl alcohol, 8 to 15 parts of phosphatidylcholine, 1 to 2 parts of polyvinyl pyrrolidone, 0.8 to 1.5 parts of nanosilver particles, 0.5 to 1 part of CeO2 nanoenzyme, 1 to 2 parts of vitamin E and 9 to 14 parts of active extracts.

[0006] Preferably, the composition of the active extract includes the following components by weight: 1-2 parts of Salvia miltiorrhiza extract, 1.5-2 parts of Carthamus tinctorius extract, 2-3 parts of Echinacea purpurea extract, 1-2 parts of capsaicin, 1.5-2 parts of Scutellaria baicalensis extract and 2-3 parts of Centella asiatica extract.

[0007] Preferably, the salvia miltiorrhiza extract, safflower extract, echinacea extract, capsaicin, scutellaria baicalensis extract and centella asiatica extract are all extracted and prepared by conventional technical means.

[0008] Preferably, the specific preparation steps of the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel are as follows:

[0009] A1: Add chitosan to 1wt% acetic acid solution, stir and dissolve evenly to obtain chitosan solution; add polyacrylic acid to deionized water, stir and dissolve evenly to obtain 1-3wt% polyacrylic acid solution; add hyaluronic acid to deionized water, stir and dissolve evenly to obtain 0.5-1wt% hyaluronic acid solution;

[0010] A2: The chitosan solution and the hyaluronic acid solution prepared in step A1 are mixed, and then slowly added to the polyacrylic acid solution, stirred evenly, and then 0.02-0.03% glutaraldehyde of the total volume of the solution is added, and stirred at 30-40° C. for 30-60 minutes to obtain a polyacrylic acid-chitosan-hyaluronic acid composite hydrogel;

[0011] Preferably, in step A1, the ratio of the amount of chitosan to the amount of acetic acid solution is 1-2 g:100 mL;

[0012] Preferably, in step A2, the volume ratio of the chitosan solution, the hyaluronic acid solution and the polyacrylic acid solution is 3-4:1:2-3.

[0013] Preferably, the specific preparation steps of the CeO2 nanozyme are as follows:

[0014] B1: adding cerium nitrate hexahydrate to deionized water, stirring and dissolving uniformly to obtain a 4-8wt% cerium nitrate solution; adding urea to deionized water, stirring and dissolving uniformly to obtain a 6-12wt% urea solution;

[0015] B2: Add the cerium nitrate solution prepared in step B1 to the urea solution, stir evenly, add PEG-400, stir at 300 rpm for 30 min, mix evenly, heat to 180-220°C, react for 8-12 h, naturally cool to room temperature, centrifuge at 8000 rpm for 10 min, filter, wash with deionized water 3 times, ultrasonically treat at 40-60 W for 10 min, and vacuum dry at 60°C to constant weight to obtain CeO2 nanozyme;

[0016] Preferably, in step B2, the volume ratio of the cerium nitrate solution to the urea solution is 1:1; and the added amount of PEG-400 is 0.5-1% of the total mass of the solution.

[0017] Preferably, another aspect of the present invention is to provide a method for preparing a diabetic foot external dressing, and the specific preparation steps are as follows:

[0018] S1: adding polyvinyl alcohol to 50-100 times by weight of deionized water, heating to 80-90°C, stirring and dissolving uniformly, cooling to room temperature, and ultrasonically treating at 60-100W for 30min to obtain a polyvinyl alcohol solution; adding phosphatidylcholine to 10-15 times by weight of chloroform, stirring and dissolving uniformly to obtain a phosphatidylcholine solution; adding nanosilver particles to deionized water to obtain a 0.1-0.2wt% nanosilver solution; adding polyvinyl pyrrolidone to deionized water, heating to 60-80°C, stirring and dissolving uniformly to obtain a 1-2wt% polyvinyl pyrrolidone solution;

[0019] S2: slowly adding the polyvinyl pyrrolidone solution prepared in step S1 to the nanosilver solution prepared in step S1, maintaining the temperature at 60-80° C., reacting for 1-2 hours, cooling to room temperature, centrifuging, repeatedly washing with deionized water for 3 times, and vacuum drying at 40° C. for 12 hours to obtain pretreated nanosilver;

[0020] S3: Dissolve vitamin E, capsaicin, salvia miltiorrhiza extract, safflower extract, echinacea extract, scutellaria baicalensis extract and centella asiatica extract in 10 parts by weight of chloroform, mix well, and obtain an active ingredient solution; stir and mix the phosphatidylcholine solution prepared in step S1 and the active ingredient solution well, perform ultrasonic treatment at 20-30W for 5 minutes, then perform rotary evaporation at 37°C to remove the solvent, and dry at 30-40°C for 2-4 hours under a nitrogen atmosphere to obtain a phosphatidylcholine film;

[0021] S4: Disperse the CeO2 nanozyme, the polyvinyl alcohol solution prepared in step S1, and the nanosilver particles prepared in step S2 into 20 times the weight of PBS buffer, and disperse them evenly by ultrasonic treatment at room temperature to obtain a hydrated solution; slowly add the hydrated solution to the phosphatidylcholine film prepared in step S3, ultrasonic treatment at 20-30W for 5min, dialysis at 10kDa for 12h, and repeat the dialysis treatment 3 times to obtain polyvinyl alcohol-phosphatidylcholine complex liposomes;

[0022] S5: adding honey, lactic acid, collagen and glycerol to the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel in sequence, stirring continuously during the addition process, and after the addition is completed, ultrasonic treatment is performed at 20-30W for 5-10min, and then the polyvinyl alcohol-phosphatidylcholine composite liposome prepared in step S4 is slowly injected, and the mixture is stirred at 60-80rpm to be uniformly mixed, and the mixture is allowed to stand at room temperature for 24h to obtain an external dressing;

[0023] Preferably, in step S3, the specific parameters of the rotary evaporation are a rotation speed of 200-300 rpm and a pressure of 500-700 mbar for evaporation for 2 hours, and then reducing the rotation speed to 100-150 rpm and evaporating at a pressure of 300-500 mbar for another 1-2 hours.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention uses a composite hydrogel carrier constructed of polyacrylic acid, chitosan and hyaluronic acid on the wound surface, and loads lactic acid and CeO2 nanozymes therein to achieve the regulation of wound pH and the sustained release of active extracts, thereby promoting wound healing. First, chitosan, polyacrylic acid and hyaluronic acid form a stable three-dimensional network structure through electrostatic action and hydrogen bonds, which improves the overall mechanical strength and elasticity of the hydrogel and provides an ideal biological scaffold for cell adhesion and proliferation. Then, the composite hydrogel is used to slowly release lactic acid to gradually adjust the wound surface, which is originally close to neutral or weakly alkaline, to a weakly acidic range. Compared with the direct release of strongly acidic substances, the gradual pH regulation helps to avoid stimulation to surrounding tissues and ensure that the active extracts play the best effect in a relatively stable acidic environment; under weakly acidic conditions, CeO2 nanozymes can efficiently catalyze the decomposition of hydrogen peroxide, produce free radicals to remove harmful pathogens and promote wound repair. The interaction between polyvinyl alcohol (PVA) and phosphatidylcholine (PC) can improve the stability and compatibility of liposomes in the hydrogel network, enhance the mechanical strength and hydrophilicity of the liposome membrane, and thus make the liposomes more evenly and firmly embedded in the hydrogel matrix to avoid early rupture or shedding. At the same time, liposomes act as carriers to encapsulate a variety of active extracts to achieve gradual release, and cooperate with lactic acid to dynamically regulate pH to ensure that each component works in the most suitable microenvironment.

[0026] In a weakly acidic microenvironment, other plant extracts and nutrients used in combination can also play a more effective role. Centella asiatica has the ability to promote collagen production, cell migration and angiogenesis. Under weakly acidic conditions, its triterpenoid compounds are more efficient in accelerating granulation tissue formation and promoting wound convergence, and constructing a matrix environment based on collagen, hyaluronic acid and chitosan that is conducive to tissue repair. Vitamin E, as a fat-soluble antioxidant, can produce free radicals to eliminate pathogens while CeO2 nanoenzymes produce free radicals, and cooperate with plant extracts such as Salvia miltiorrhiza and Scutellaria baicalensis that have anti-inflammatory and antioxidant properties to reduce excessive oxidative stress and inflammatory response in local tissues, making the wound healing process more balanced and orderly. Salvia miltiorrhiza and safflower extracts also show more stable performance in a slightly acidic environment. Their active ingredients help improve local microcirculation, promote blood supply and nutrient delivery, and play an anti-inflammatory role; they work together with the natural antibacterial and tissue regeneration properties of chitosan to accelerate wound healing. The high osmotic pressure and rich nutrients of honey can maintain the moisture and nutrient supply of the wound surface, and form a superimposed effect with the hydration environment of hyaluronic acid to promote the growth of granulation tissue. In addition, Echinacea extract is easier to maintain the stability and bioavailability of the active ingredients under weakly acidic conditions, and its immunomodulatory and anti-inflammatory properties can be fully exerted; in synergy with lactic acid and CeO2 nanozymes, Echinacea helps to improve the local immune microenvironment, reduce excessive inflammatory reactions, and thus promote tissue regeneration and wound closure.

[0027] In summary, the present invention utilizes lactic acid to regulate the pH of the wound surface, so that the CeO2 nanozyme and various active extracts can function under the optimal environment. Through the comprehensive properties of moisturizing, antibacterial and promoting tissue regeneration provided by the hydrogel constructed by polyacrylic acid, chitosan and hyaluronic acid, the CeO2 nanozyme, various plant extracts and nutrients can synergistically effectively inhibit bacteria and promote wound healing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a biocompatibility test diagram of the external dressings prepared in Examples 1 to 3 of the present invention and Comparative Example 4;

[0030] Figure 2 It is a test chart of the antibacterial property of the external dressings prepared in Example 2 of the present invention and Comparative Examples 1 to 4;

[0031] Figure 3 is a SEM scanning electron microscope image of the external dressing prepared in Example 2 of the present invention;

[0032] Figure 4 It is a sustained-release test chart of the external dressings prepared in Example 2 of the present invention and Comparative Examples 1 and 4;

[0033] Figure 5 It is a stability test chart of the external dressings prepared in Example 2 of the present invention and Comparative Example 4. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the raw materials involved in the present invention are purchased through conventional commercial channels.

[0035] Example 1: A diabetic foot external dressing, comprising a hydrogel matrix and liposomes; the hydrogel matrix comprises the following ingredients in parts by weight: 80 parts of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, 12 parts of honey, 3 parts of lactic acid, 8 parts of collagen and 5 parts of glycerol; the liposomes comprise the following ingredients in parts by weight: 5 parts of polyvinyl alcohol, 8 parts of phosphatidylcholine, 1 part of polyvinyl pyrrolidone, 0.8 parts of nanosilver particles, 0.5 parts of CeO2 nanoenzymes, 1 part of vitamin E and 9 parts of active extracts.

[0036] The composition of the active extract includes the following components by weight: 1 part of salvia miltiorrhiza extract, 1.5 parts of safflower extract, 2 parts of echinacea extract, 1 part of capsaicin, 1.5 parts of scutellaria baicalensis extract and 2 parts of centella asiatica extract.

[0037] Salvia miltiorrhiza extract, safflower extract, echinacea extract, capsaicin, scutellaria baicalensis extract and Centella asiatica extract are all extracted and prepared by conventional technical means.

[0038] The specific preparation steps of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel are as follows:

[0039] A1: Add 5g chitosan to 500mL 1wt% acetic acid solution, stir and dissolve evenly to obtain a chitosan solution; add 2g polyacrylic acid to 200mL deionized water, stir and dissolve evenly to obtain a 1wt% polyacrylic acid solution; add 0.5g hyaluronic acid to 100mL deionized water, stir and dissolve evenly to obtain a 0.5wt% hyaluronic acid solution;

[0040] A2: 300 mL of chitosan solution and 100 mL of hyaluronic acid solution prepared in step A1 were mixed, and then slowly added to 200 mL of polyacrylic acid solution, stirred evenly, and then 0.12 mL of glutaraldehyde was added, and stirred for reaction at 30°C for 60 min to obtain a polyacrylic acid-chitosan-hyaluronic acid composite hydrogel;

[0041] The specific preparation steps of CeO2 nanozyme are as follows:

[0042] B1: Add 8 g of cerium nitrate hexahydrate to 200 mL of deionized water, stir and dissolve evenly to obtain a 4 wt% cerium nitrate solution; add 12 g of urea to 200 mL of deionized water, stir and dissolve evenly to obtain a 6 wt% urea solution;

[0043] B2: Add 200 mL of cerium nitrate solution prepared in step B1 to 200 mL of urea solution, stir evenly, add 2 g of PEG-400, stir at 300 rpm for 30 min, mix evenly, heat to 180 ° C, react for 12 h, naturally cool to room temperature, centrifuge at 8000 rpm for 10 min, filter, wash with deionized water 3 times, ultrasonically treat at 40 W for 10 min, and vacuum dry at 60 ° C to constant weight to obtain CeO2 nanozyme;

[0044] The specific preparation steps of diabetic foot dressing are as follows:

[0045] S1: Add polyvinyl alcohol to 100 parts by weight of deionized water, heat to 80°C, stir and dissolve evenly, cool to room temperature, and perform ultrasonic treatment at 60W for 30 minutes to obtain a polyvinyl alcohol solution; add phosphatidylcholine to 10 parts by weight of chloroform, stir and dissolve evenly to obtain a phosphatidylcholine solution; add nanosilver particles to deionized water to obtain a 0.1wt% nanosilver solution; add polyvinyl pyrrolidone to deionized water, heat to 60°C, stir and dissolve evenly to obtain a 1wt% polyvinyl pyrrolidone solution;

[0046] S2: slowly adding the polyvinyl pyrrolidone solution prepared in step S1 to the nanosilver solution prepared in step S1, maintaining the temperature at 60°C, reacting for 2 hours, cooling to room temperature, centrifuging, repeatedly washing with deionized water for 3 times, and vacuum drying at 40°C for 12 hours to obtain pretreated nanosilver;

[0047] S3: Dissolve vitamin E, capsaicin, salvia miltiorrhiza extract, safflower extract, echinacea extract, scutellaria baicalensis extract and centella asiatica extract in 10 times the weight of chloroform, mix well, and obtain an active ingredient solution; stir and mix the phosphatidylcholine solution prepared in step S1 and the active ingredient solution well, perform ultrasonic treatment at 20W for 5 minutes, and then perform rotary evaporation at 37°C to remove the solvent, with specific parameters of evaporation at a speed of 200 rpm and a pressure of 500 mbar for 2 hours, then reduce the speed to 100 rpm, evaporate at a pressure of 300 mbar for another 2 hours, and dry at 30°C for 4 hours under a nitrogen atmosphere to obtain a phosphatidylcholine film;

[0048] S4: Disperse the CeO2 nanozyme, the polyvinyl alcohol solution prepared in step S1, and the nanosilver particles prepared in step S2 into 20 times the weight of PBS buffer, and disperse them evenly by ultrasonic treatment at room temperature to obtain a hydrated solution; slowly add the hydrated solution to the phosphatidylcholine film prepared in step S3, ultrasonic treatment at 20W for 5 minutes, and dialysis at 10kDa for 12 hours, and repeat the dialysis treatment for 3 times to obtain polyvinyl alcohol-phosphatidylcholine complex liposomes;

[0049] S5: Add honey, lactic acid, collagen and glycerol to the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel in sequence, and continue stirring during the addition process. After the addition is completed, ultrasonic treatment is performed at 20W for 10 minutes, and then the polyvinyl alcohol-phosphatidylcholine composite liposome prepared in step S4 is slowly injected, and the mixture is stirred at 70rpm to be evenly mixed. The mixture is allowed to stand at room temperature for 24 hours to obtain an external dressing.

[0050] Example 2: A diabetic foot external dressing, comprising a hydrogel matrix and liposomes; the hydrogel matrix comprises the following ingredients in parts by weight: 95 parts of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, 15 parts of honey, 4 parts of lactic acid, 10 parts of collagen and 8 parts of glycerol; the liposomes comprise the following ingredients in parts by weight: 7 parts of polyvinyl alcohol, 12 parts of phosphatidylcholine, 1.5 parts of polyvinyl pyrrolidone, 1 part of nanosilver particles, 1 part of CeO2 nanozyme, 1.5 parts of vitamin E and 14 parts of active extracts.

[0051] The composition of the active extract includes the following components by weight: 2 parts of salvia miltiorrhiza extract, 2 parts of safflower extract, 3 parts of echinacea extract, 2 parts of capsaicin, 2 parts of scutellaria baicalensis extract and 3 parts of centella asiatica extract.

[0052] Salvia miltiorrhiza extract, safflower extract, echinacea extract, capsaicin, scutellaria baicalensis extract and Centella asiatica extract are all extracted and prepared by conventional technical means.

[0053] The specific preparation steps of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel are as follows:

[0054] A1: Add 10g chitosan to 500mL 1wt% acetic acid solution, stir and dissolve evenly to obtain a chitosan solution; add 9g polyacrylic acid to 300mL deionized water, stir and dissolve evenly to obtain a 3wt% polyacrylic acid solution; add 1g hyaluronic acid to 100mL deionized water, stir and dissolve evenly to obtain a 1wt% hyaluronic acid solution;

[0055] A2: 400 mL of chitosan solution and 100 mL of hyaluronic acid solution prepared in step A1 were mixed, and then slowly added to 300 mL of polyacrylic acid solution, stirred evenly, and then 0.2 mL of glutaraldehyde was added to the total volume of the solution, and stirred for reaction at 38°C for 45 minutes to obtain a polyacrylic acid-chitosan-hyaluronic acid composite hydrogel;

[0056] The specific preparation steps of CeO2 nanozyme are as follows:

[0057] B1: Add 16 g of cerium nitrate hexahydrate to 200 mL of deionized water, stir and dissolve evenly to obtain an 8 wt % cerium nitrate solution; add 24 g of urea to 200 mL of deionized water, stir and dissolve evenly to obtain a 12 wt % urea solution;

[0058] B2: Add 200 mL of cerium nitrate solution prepared in step B1 to 200 mL of urea solution, stir evenly, add 4 g of PEG-400, stir at 300 rpm for 30 min, mix evenly, heat to 200 ° C, react for 10 h, naturally cool to room temperature, centrifuge at 8000 rpm for 10 min, filter, wash with deionized water for 3 times, ultrasonically treat at 50 W for 10 min, and vacuum dry at 60 ° C to constant weight to obtain CeO2 nanozyme;

[0059] The specific preparation steps of diabetic foot dressing are as follows:

[0060] S1: Add polyvinyl alcohol to 80 parts by weight of deionized water, heat to 85°C, stir and dissolve evenly, cool to room temperature, and perform ultrasonic treatment at 80W for 30min to obtain a polyvinyl alcohol solution; add phosphatidylcholine to 12 parts by weight of chloroform, stir and dissolve evenly to obtain a phosphatidylcholine solution; add nanosilver particles to deionized water to obtain a 0.15wt% nanosilver solution; add polyvinyl pyrrolidone to deionized water, heat to 70°C, stir and dissolve evenly to obtain a 1.5wt% polyvinyl pyrrolidone solution;

[0061] S2: slowly adding the polyvinyl pyrrolidone solution prepared in step S1 to the nanosilver solution prepared in step S1, maintaining the temperature at 70°C, reacting for 1.5 hours, cooling to room temperature, centrifuging, repeatedly washing with deionized water for 3 times, and vacuum drying at 40°C for 12 hours to obtain pretreated nanosilver;

[0062] S3: Dissolve vitamin E, capsaicin, salvia miltiorrhiza extract, safflower extract, echinacea extract, scutellaria baicalensis extract and centella asiatica extract in 10 times the weight of chloroform, mix well, and obtain an active ingredient solution; stir and mix the phosphatidylcholine solution prepared in step S1 and the active ingredient solution well, perform ultrasonic treatment at 30W for 5 minutes, and then perform rotary evaporation at 37°C to remove the solvent, with specific parameters of evaporation at a speed of 250 rpm and a pressure of 700 mbar for 2 hours, then reduce the speed to 150 rpm, and evaporate at a pressure of 500 mbar for another hour, and dry at 35°C for 3 hours under a nitrogen atmosphere to obtain a phosphatidylcholine film;

[0063] S4: Disperse the CeO2 nanozyme, the polyvinyl alcohol solution prepared in step S1, and the nanosilver particles prepared in step S2 into 20 times the weight of PBS buffer, and disperse them evenly by ultrasonic treatment at room temperature to obtain a hydrated solution; slowly add the hydrated solution to the phosphatidylcholine film prepared in step S3, ultrasonic treatment at 30W for 5 minutes, and dialyze at 10kDa for 12 hours, repeat the dialysis treatment 3 times, and obtain polyvinyl alcohol-phosphatidylcholine composite liposomes;

[0064] S5: Add honey, lactic acid, collagen and glycerol to the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel in sequence, and continue stirring during the addition process. After the addition is completed, ultrasonic treatment is performed at 30W for 5 minutes, and then the polyvinyl alcohol-phosphatidylcholine composite liposome prepared in step S4 is slowly injected, and the mixture is stirred at 60rpm to be evenly mixed. The mixture is allowed to stand at room temperature for 24 hours to obtain an external dressing.

[0065] Example 3: A diabetic foot external dressing, comprising a hydrogel matrix and liposomes; the hydrogel matrix comprises the following ingredients in parts by weight: 100 parts of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, 18 parts of honey, 3.5 parts of lactic acid, 12 parts of collagen and 10 parts of glycerol; the liposomes comprise the following ingredients in parts by weight: 8 parts of polyvinyl alcohol, 15 parts of phosphatidylcholine, 2 parts of polyvinyl pyrrolidone, 1.5 parts of nanosilver particles, 0.8 parts of CeO2 nanoenzymes, 2 parts of vitamin E and 11 parts of active extracts.

[0066] The composition of the active extract includes the following components by weight: 1.5 parts of salvia miltiorrhiza extract, 1.7 parts of safflower extract, 2.5 parts of echinacea extract, 1.5 parts of capsaicin, 1.8 parts of scutellaria baicalensis extract and 2.5 parts of centella asiatica extract.

[0067] Salvia miltiorrhiza extract, safflower extract, echinacea extract, capsaicin, scutellaria baicalensis extract and Centella asiatica extract are all extracted and prepared by conventional technical means.

[0068] The specific preparation steps of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel are as follows:

[0069] A1: Add 8g chitosan to 500mL 1wt% acetic acid solution, stir and dissolve evenly to obtain a chitosan solution; add 6g polyacrylic acid to 300mL deionized water, stir and dissolve evenly to obtain a 2wt% polyacrylic acid solution; add 0.8g hyaluronic acid to 100mL deionized water, stir and dissolve evenly to obtain a 0.8wt% hyaluronic acid solution;

[0070] A2: 350 mL of chitosan solution and 100 mL of hyaluronic acid solution prepared in step A1 were mixed, and then slowly added to 250 mL of polyacrylic acid solution, stirred evenly, and then 0.21 mL of glutaraldehyde was added to the total volume of the solution, and stirred for reaction at 40°C for 30 minutes to obtain a polyacrylic acid-chitosan-hyaluronic acid composite hydrogel;

[0071] The specific preparation steps of CeO2 nanozyme are as follows:

[0072] B1: Add 12 g of cerium nitrate hexahydrate to 200 mL of deionized water, stir and dissolve evenly to obtain a 6 wt % cerium nitrate solution; add 18 g of urea to 200 mL of deionized water, stir and dissolve evenly to obtain a 9 wt % urea solution;

[0073] B2: Add 200 mL of cerium nitrate solution prepared in step B1 to 200 mL of urea solution, stir evenly, add 3 g of PEG-400, stir at 300 rpm for 30 min, mix evenly, heat to 220 ° C, react for 8 h, naturally cool to room temperature, centrifuge at 8000 rpm for 10 min, filter, wash with deionized water for 3 times, ultrasonically treat at 60 W for 10 min, and vacuum dry at 60 ° C to constant weight to obtain CeO2 nanozyme;

[0074] The specific preparation steps of diabetic foot dressing are as follows:

[0075] S1: Add polyvinyl alcohol to 100 parts by weight of deionized water, heat to 90°C, stir and dissolve evenly, cool to room temperature, and ultrasonically treat at 100W for 30 minutes to obtain a polyvinyl alcohol solution; add phosphatidylcholine to 15 parts by weight of chloroform, stir and dissolve evenly to obtain a phosphatidylcholine solution; add nanosilver particles to deionized water to obtain a 0.2wt% nanosilver solution; add polyvinyl pyrrolidone to deionized water, heat to 80°C, stir and dissolve evenly to obtain a 2wt% polyvinyl pyrrolidone solution;

[0076] S2: slowly adding the polyvinyl pyrrolidone solution prepared in step S1 to the nanosilver solution prepared in step S1, maintaining the temperature at 80°C, reacting for 1 hour, cooling to room temperature, centrifuging, repeatedly washing with deionized water for 3 times, and vacuum drying at 40°C for 12 hours to obtain pretreated nanosilver;

[0077] S3: Dissolve vitamin E, capsaicin, salvia miltiorrhiza extract, safflower extract, echinacea extract, scutellaria baicalensis extract and centella asiatica extract in 10 times the weight of chloroform, mix well, and obtain an active ingredient solution; stir and mix the phosphatidylcholine solution prepared in step S1 and the active ingredient solution well, perform ultrasonic treatment at 25W for 5 minutes, and then perform rotary evaporation at 37°C to remove the solvent, with specific parameters of evaporation at a speed of 250 rpm and a pressure of 600 mbar for 2 hours, then reduce the speed to 120 rpm, evaporate at a pressure of 400 mbar for another 1.5 hours, and dry at 40°C for 2 hours under a nitrogen atmosphere to obtain a phosphatidylcholine film;

[0078] S4: Disperse the CeO2 nanozyme, the polyvinyl alcohol solution prepared in step S1, and the nanosilver particles prepared in step S2 into 20 times the weight of PBS buffer, and disperse them evenly by ultrasonic treatment at room temperature to obtain a hydrated solution; slowly add the hydrated solution to the phosphatidylcholine film prepared in step S3, ultrasonic treatment at 25W for 5 minutes, and dialysis at 10kDa for 12 hours, and repeat the dialysis treatment 3 times to obtain polyvinyl alcohol-phosphatidylcholine complex liposomes;

[0079] S5: Add honey, lactic acid, collagen and glycerol to the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel in sequence, and continue stirring during the addition process. After the addition is completed, ultrasonic treatment is performed at 25W for 6 minutes, and then the polyvinyl alcohol-phosphatidylcholine composite liposome prepared in step S4 is slowly injected, and the mixture is stirred at 80rpm to be evenly mixed. The mixture is allowed to stand at room temperature for 24 hours to obtain an external dressing.

[0080] Comparative Example 1: The operation of Comparative Example 1 is substantially the same as that of Example 2, except that lactic acid is not added in Comparative Example 1.

[0081] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 2, except that CeO2 nanozyme is not added in Comparative Example 2.

[0082] Comparative Example 3: The operation of Comparative Example 3 is basically the same as that of Example 2, except that no active extracts (Salvia miltiorrhiza extract, Carthamus tinctorius extract, Echinacea purpurea extract, capsaicin, Scutellaria baicalensis extract and Centella asiatica extract) are added in Comparative Example 3.

[0083] Comparative Example 4: The operation of Comparative Example 4 is basically the same as that of Example 2, except that chitosan hydrogel is used in Comparative Example 4 to replace the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel.

[0084] Performance Test:

[0085] Biocompatibility test: The external dressing samples prepared in Examples 1 to 3 and Comparative Example 4 were placed at the bottom of the culture plate, and 8 wells of each sample group were evenly distributed in a 96-well plate. 50 μL of DMEM medium was added to each well, and then Fibroblasts were diluted to 1×10 4 After 50 μL of 5 mg / mL of MTT solution was added to the wells, the temperature was set to 37°C and the CO2 concentration was 5%. After 24 hours of incubation, 5 μL of 5 mg / mL MTT solution was added. After further incubation for 4 hours, the culture medium in the wells was aspirated, and then 50 μL of dimethyl sulfoxide was added to the wells. The absorbance (OD value) was measured at 490 nm using a microplate reader, and the activity percentage was calculated [biocompatibility (%) = (OD value of the embodiment - OD value of the negative control group) / (OD value of the positive control group - OD value of the negative control group) × 100%], the positive control group: treated with 10wt% dimethyl sulfoxide solution; the negative control group: untreated cells were used as the control; the cell survival rate results are shown in FIG. Figure 1 shown.

[0086] Depend on Figure 1 The results show that the topical dressing prepared by the present invention has excellent biocompatibility, does not cause obvious toxicological damage to cells, and can be used safely and effectively; from the results of Comparative Example 4 and Example 2, it can be seen that the composite hydrogel prepared by a special ratio has better biocompatibility than chitosan hydrogel, and the stability of chitosan hydrogel is poor, which may lead to the rapid release of active substances such as lactic acid, collagen and honey, resulting in a significant impact on cell activity.

[0087] Antibacterial test: fresh bacterial suspensions of Staphylococcus aureus, Escherichia coli and Candida albicans were prepared at a concentration of 1×10 8 CFU / mL, add the external dressing samples (50 mg + 10 mL pH 7.4 PBS buffer) prepared in Example 2 of the present invention and Comparative Examples 1 to 4 respectively, place the mixed bacterial solution in a constant temperature oscillator at 37°C for 48 h, record the total number of colonies by plate colony counting method, use the bacterial solution without sample as control (the strains used in this experiment were all purchased from the market), and calculate the antibacterial rate [inhibition rate (%) = (1-the number of bacteria in the control sample / the number of bacteria in the experimental sample) × 100%], the results are as follows Figure 2 shown.

[0088] Depend on Figure 2The results show that the topical dressing prepared by the present invention can effectively inhibit the growth of Staphylococcus aureus, Escherichia coli and Candida albicans, and has excellent antibacterial properties; from the results of Comparative Example 1 and Example 2, it can be seen that the lack of the synergistic regulatory effect of lactic acid has affected the effects of CeO2 nanozymes and various active extracts. In addition, the lack of inhibition of bacteria by the acidic environment also affects the antibacterial performance; from the results of Comparative Example 2 and Example 2, it can be seen that the lack of the oxidizing effect of CeO2 nanozymes has significantly affected the inhibitory effect on the fungus Candida albicans; from the results of Comparative Example 3 and Example 2, it can be seen that the lack of the synergistic effect of active extracts has significantly affected the overall inhibitory effect on bacteria; from the results of Comparative Example 4 and Example 2, it can be seen that the lack of the synergistic effect of hydrogel has also affected the inhibitory performance on bacteria to a certain extent.

[0089] Spectrum test: Scanning electron microscope was used to observe the microstructure of the external dressing sample prepared in Example 2 of the present invention, and a SEM scanning electron microscope image was obtained. The results are as follows: Figure 3 shown.

[0090] Depend on Figure 3 The results show that the image has a large number of pores and an obvious porous network structure, and the high surface roughness is extremely conducive to the storage and release of lactic acid. The overall structure of the composite gel and the loaded material is complete.

[0091] Sustained release test: 1 g of the external dressing samples prepared in Example 2 and Comparative Examples 1 and 4 were added to 50 mL of normal saline (pH 7), and the samples were placed in a constant temperature shaker at 37°C and slowly stirred at 60 rpm. 0.5 mL of samples were taken at 0 h, 1 h, 2 h, 4 h, 8 h, 12 h, 18 h and 24 h to measure the pH. After each sampling, an equal volume of PBS buffer was added and the pH changes were recorded. The results are shown in the figure. Figure 4 shown.

[0092] Depend on Figure 4 As can be seen from the results, the topical dressing prepared by the present invention can effectively and slowly lower the pH, achieve the sustained release of lactic acid, and effectively avoid the stress caused by rapid release leading to too rapid a decrease in acidity; from the results of Comparative Example 1 and Example 2, it can be seen that the lack of pH regulation for sustained release of lactic acid, the weak acid release of chitosan and the buffering capacity of the hydrogel matrix slightly reduce the pH in the early stage, but the overall pH decrease in the middle and late stages remains stable; from the results of Comparative Example 4 and Example 2, it can be seen that due to the lack of network synergy of polyacrylic acid and hyaluronic acid, the release of lactic acid is not stable enough, and the loose structure of chitosan will cause lactic acid to be quickly released in the early stage, resulting in too rapid a decrease in pH in the early stage, followed by a rapid decrease in the release rate, and the pH regulation performance is significantly affected.

[0093] Stability test: The external dressing samples prepared in Example 2 of the present invention and Comparative Example 4 were sealed in commercial packaging and placed at a temperature of 35°C and a relative humidity of 75% for 6 months. Samples were taken once in the first, second, third and sixth months of the test period to test the pH value. The results were as follows: Figure 5 shown.

[0094] Depend on Figure 5 The results show that the topical gel prepared by the present invention can be effectively preserved for a long time, and its active substances (lactic acid, collagen, honey, vitamin E and active extracts) are effectively loaded and encapsulated, and the preparation of the topical dressing is reliable and effective, showing excellent stability; from the results of Comparative Example 4 and Example 2, it can be seen that when chitosan hydrogel is used to replace the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, the mechanical properties of the hydrogel itself are seriously affected, it is easy to disintegrate in long-term tests, and its compatibility with liposomes is significantly reduced, and the stability is poor.

[0095] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A diabetic foot external dressing, characterized in that: The composition includes a hydrogel matrix and a liposome; the composition of the hydrogel matrix includes the following components in parts by weight: 80 to 100 parts of polyacrylic acid-chitosan-hyaluronic acid composite hydrogel, 12 to 18 parts of honey, 3 to 4 parts of lactic acid, 8 to 12 parts of collagen and 5 to 10 parts of glycerol; the composition of the liposome includes the following components in parts by weight: 5 to 8 parts of polyvinyl alcohol, 8 to 15 parts of phosphatidylcholine, 1 to 2 parts of polyvinyl pyrrolidone, 0.8 to 1.5 parts of nano silver particles, 0.5 to 1 part of CeO2 nano enzymes, 1 to 2 parts of vitamin E and 9 to 14 parts of active extracts; The specific preparation steps of the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel are as follows: A1: Add chitosan to acetic acid solution, stir and dissolve evenly to obtain chitosan solution; add polyacrylic acid to deionized water, stir and dissolve evenly to obtain polyacrylic acid solution; add hyaluronic acid to deionized water, stir and dissolve evenly to obtain hyaluronic acid solution; A2: The chitosan solution and hyaluronic acid solution prepared in step A1 are mixed, and then slowly added into the polyacrylic acid solution, stirred evenly, and then glutaraldehyde is added, stirred and reacted to obtain a polyacrylic acid-chitosan-hyaluronic acid composite hydrogel.

2. A diabetic foot external dressing according to claim 1, characterized in that: The active extract comprises the following components by weight: 1-2 parts of salvia miltiorrhiza extract, 1.5-2 parts of safflower extract, 2-3 parts of echinacea extract, 1-2 parts of capsaicin, 1.5-2 parts of scutellaria baicalensis extract and 2-3 parts of centella asiatica extract.

3. A diabetic foot external dressing according to claim 2, characterized in that: In step A1, the ratio of the chitosan to the acetic acid solution is 1-2 g:100 mL.

4. A diabetic foot external dressing according to claim 3, characterized in that: In step A2, the volume ratio of the chitosan solution, the hyaluronic acid solution and the polyacrylic acid solution is 3-4:1:2-3.

5. The diabetic foot external dressing according to claim 4, characterized in that: The specific preparation steps of the CeO2 nanozyme are as follows: B1: adding cerium nitrate hexahydrate to deionized water, stirring and dissolving uniformly to obtain a cerium nitrate solution; adding urea to deionized water, stirring and dissolving uniformly to obtain a urea solution; B2: Add the cerium nitrate solution prepared in step B1 to the urea solution, stir evenly, add PEG-400, stir, mix evenly, heat, and after the reaction is completed, naturally cool to room temperature, centrifuge, filter, repeatedly wash with deionized water, ultrasonically treat, and vacuum dry to constant weight to obtain CeO2 nanozyme.

6. A diabetic foot external dressing according to claim 5, characterized in that: In step B2, the volume ratio of the cerium nitrate solution to the urea solution is 1:1; the added amount of the PEG-400 is 0.5-1% of the total mass of the solution.

7. A method for preparing the diabetic foot external dressing according to any one of claims 1 to 6, characterized in that: The specific preparation steps are as follows: S1: adding polyvinyl alcohol to deionized water, heating, stirring and dissolving uniformly, cooling to room temperature, and ultrasonic treatment to obtain a polyvinyl alcohol solution; adding phosphatidylcholine to chloroform, stirring and dissolving uniformly, and obtaining a phosphatidylcholine solution; adding nanosilver particles to deionized water to obtain a nanosilver solution; adding polyvinyl pyrrolidone to deionized water, heating, stirring and dissolving uniformly, and obtaining a polyvinyl pyrrolidone solution; S2: slowly adding the polyvinyl pyrrolidone solution prepared in step S1 to the nanosilver solution prepared in step S1, maintaining the temperature for reaction, cooling to room temperature, centrifuging, repeatedly washing with deionized water, and vacuum drying to obtain pretreated nanosilver; S3: dissolving vitamin E, capsaicin, salvia miltiorrhiza extract, safflower extract, echinacea extract, scutellaria baicalensis extract and centella asiatica extract in chloroform, and mixing them evenly to obtain an active ingredient solution; stirring and mixing the phosphatidylcholine solution prepared in step S1 and the active ingredient solution evenly, ultrasonically treating, and then rotary evaporating to remove the solvent, and drying under a nitrogen atmosphere to obtain a phosphatidylcholine film; S4: dispersing the CeO2 nanozyme, the polyvinyl alcohol solution prepared in step S1, and the nanosilver particles prepared in step S2 into a PBS buffer solution, and dispersing them uniformly by ultrasonic treatment at room temperature to obtain a hydrated solution; slowly adding the hydrated solution into the phosphatidylcholine film prepared in step S3, ultrasonic treatment, dialyzing, and repeating the dialysis treatment to obtain polyvinyl alcohol-phosphatidylcholine composite liposomes; S5: Add honey, lactic acid, collagen and glycerol to the polyacrylic acid-chitosan-hyaluronic acid composite hydrogel in sequence, and continue stirring during the addition process. After the addition is completed, ultrasonic treatment is performed, and then the polyvinyl alcohol-phosphatidylcholine composite liposome prepared in step S4 is slowly injected, and the mixture is stirred to mix evenly, and allowed to stand at room temperature to obtain an external dressing.

8. The method for preparing a diabetic foot external dressing according to claim 7, characterized in that: In step S3, the specific parameters of the rotary evaporation are a rotation speed of 200-300 rpm, a pressure of 500-700 mbar, and evaporation for 2 hours, and then reducing the rotation speed to 100-150 rpm and evaporating at a pressure of 300-500 mbar for another 1-2 hours.

Images