Oral ulcer gel dressing as well as preparation method and application thereof

Abstract

The invention belongs to the field of oral cavity medicines, and provides an oral ulcer gel dressing as well as a preparation method and application thereof. The characteristics of high-crosslinking granular sodium hyaluronate are utilized to reduce the water absorption and expansibility of the product, and meanwhile, the synergistic effect of micro-nano hyaluronic acid particles and macromolecules endows the gel with the shear thinning characteristic of non-Newtonian fluid: in a static state, the gel shows relatively high adhesiveness and can firmly cover the wound surface of oral mucosa; when an external force is applied or applied, the viscosity is obviously reduced, so that more convenient operability and distribution uniformity are realized; the polymer material further enhances the thickening performance and biological adhesiveness of the gel, so that the gel can be tightly combined with the surface of the oral mucosa, has multiple functions of resisting bacteria, preserving moisture, promoting healing and the like, and is suitable for treatment and nursing of mucosal lesions such as oral ulcer and the like.

Description

Technical Field

[0001] The invention belongs to the field of oral medical drugs and relates to an oral ulcer gel dressing and a preparation method and application thereof. Background Art

[0002] Oral ulcers, commonly known as "mouth sores," are common ulcerative lesions that occur in the oral mucosa. It is estimated that approximately 10% of the population in China experience recurrent oral ulcers. In addition to medication or vitamin supplements, gels made from hydrophilic polymer biomaterials such as chitosan, sodium hyaluronate, and carbomer are widely used clinically to relieve oral ulcer pain and accelerate healing. These polymers coat the lesions on the oral mucosa, forming a thin film that protects the wound and prevents bacterial infection. The stable polymer film also provides a biological scaffold for the growth of normal cells, thereby accelerating the directional proliferation of epithelial cells and shortening the ulcer healing process. However, the oral environment is complex and humid. Currently available products are highly absorbent and rapidly expand after absorbing saliva in the mouth, reducing their viscosity and making it difficult for them to remain in the ulcer site for a long time, thus significantly reducing their therapeutic effectiveness. Furthermore, given the diverse locations of ulcers, including the tongue, periodontal area, cheeks, and soft palate, gels require strong fluidity to facilitate application and coverage of wounds of varying shapes.

[0003] Existing drugs for treating oral ulcers or oral inflammation usually apply the drugs directly to the wound or apply them on a patch. Due to the moist environment of the oral cavity, there are problems such as short drug residence time and poor treatment effect. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide an oral ulcer gel dressing, a preparation method thereof, and an application thereof. The invention comprises the following steps: preparing sodium hyaluronate into nanoparticles, and then self-assembling the nanogel dressing with carboxymethyl chitosan and carbomer gel; the nanogel has a shear-thinning property, and its viscosity decreases when applied, so that the gel is evenly dispersed and covers the wound tissue; the viscosity recovers after application, thereby improving the adhesion time of the gel; the carboxymethyl chitosan and carbomer give the gel excellent thickening properties and bioadhesion, ensuring that it adheres to the wound surface for a long time in the moist environment of the oral cavity; the sodium hyaluronate and carboxymethyl chitosan carry a large number of carboxyl groups, amino groups, and hydroxyl groups, and can load a variety of antibacterial and anti-inflammatory drugs through electrostatic effects, hydrogen bonds, and the like; the thioether bonds in the carboxymethyl chitosan break when exposed to active oxygen, so that the drugs are gradually released, thereby prolonging the residence time of the drugs in the oral cavity and improving the therapeutic effect.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing an oral ulcer gel dressing, the preparation method comprising:

[0007] S1, mixing NaOH solution with 1,4-butanediol diglycidyl ether, then adding sodium hyaluronate powder, stirring evenly, cross-linking to obtain a gel, dialyzing, and then cyclic granulation and ultrasonication to obtain HA nanoparticles;

[0008] S2, mixing the carboxymethyl chitosan solution with 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, adding a catalyst, and reacting to obtain a carboxymethyl chitosan gel;

[0009] S3, adding carboxymethyl chitosan gel, carbomer and HA nanoparticles into normal saline and dispersing them evenly to obtain an oral ulcer gel dressing.

[0010] Specifically include:

[0011] S1, mixing NaOH solution with 1,4-butanediol diglycidyl ether, then adding sodium hyaluronate powder, stirring evenly, reacting and dialyzing to obtain a gel, pouring the gel into a gel granulator for extrusion to obtain HA nanoparticles;

[0012] S2, mixing the carboxymethyl chitosan solution with 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, adding a catalyst, and reacting to obtain a carboxymethyl chitosan gel;

[0013] S3, adding carboxymethyl chitosan gel, carbomer and HA nanoparticles into normal saline and dispersing them evenly to obtain an oral ulcer gel dressing.

[0014] A NaOH solution was mixed with 1,4-butanediol diglycidyl ether. As a bifunctional epoxy compound, 1,4-butanediol diglycidyl ether contains reactive epoxy groups in its molecular structure. These groups readily undergo nucleophilic ring-opening reactions under alkaline conditions, leading to cross-linking reactions with nucleophilic groups in other molecules, such as hydroxyl and carboxyl groups. In this process, NaOH not only acts as a basic modifier for the solution but also enhances the electrophilicity of the epoxy groups, promoting reactivity. Subsequently, sodium hyaluronate powder was introduced into the reaction system. Sodium hyaluronate is a bioactive high-molecular-weight polysaccharide with numerous hydroxyl and carboxyl groups in its molecular chains. Under alkaline conditions, the carboxyl groups ionize to form carboxyl groups, while the hydroxyl groups act as the primary nucleophile, undergoing nucleophilic addition reactions with the epoxy groups of 1,4-butanediol diglycidyl ether. The cross-linking reaction results in the formation of a three-dimensional interpenetrating network structure between the sodium hyaluronate molecular chains through covalent bonds. This cross-linked structure significantly improves the mechanical strength, water absorption, and stability of the gel. The resulting crude gel product is extruded and ultrasonically treated multiple times in a gel granulator to produce nanoparticles. Due to their high specific surface area and excellent dispersibility, HA nanoparticles can significantly improve the uniformity and functionality of the material during subsequent preparation. Furthermore, HA nanoparticles retain the hygroscopicity and bioactivity of sodium hyaluronate, making them important in oral ulcer dressings, including promoting ulcer healing, improving material fluidity, and prolonging retention time at the lesion site.

[0015] Carboxymethyl chitosan reacts with 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid in the presence of EDC·HCl and NHS catalysts to produce a carboxymethyl chitosan gel containing thioether bonds. Carboxymethyl chitosan is a natural polymer with both negative and positive charges. Its molecules contain numerous hydroxyl (-OH), amino (-NH3), and carboxyl (-COOH) functional groups. In aqueous solution, it can form stable composites with other components through intermolecular hydrogen bonding and electrostatic interactions. Carbomer is a high-molecular-weight acrylic polymer with numerous carboxyl (-COOH) groups on its molecular chain. In aqueous solution, it ionizes to generate a negative charge, forming a network structure with excellent thickening and gelling abilities. HA nanoparticles are highly hydrophilic materials with hydroxyl (-OH) and carboxyl (-COOH) groups on their surface. In aqueous solution, they can form stable composites with other components through intermolecular hydrogen bonding and electrostatic interactions. However, if the component concentration is too low and the interparticle spacing is too large, non-covalent interactions (hydrogen bonding and electrostatics) are insufficient to drive self-assembly, resulting in a dispersed nanosuspension with no network structure. If the concentration is too high, the particles become overcrowded, prone to agglomeration due to local charge imbalance, resulting in a sudden increase in viscosity but poor uniformity. By adjusting the ratio and concentration of the three components, HA nanoparticles serve as crosslinking points, while carboxymethyl chitosan and carbomer serve as "bridges," creating a continuous three-dimensional network structure with multiple interactions. For example, electrostatic attraction between -COO- and -NH3+ occurs, while hydrogen bonds (e.g., -OH…O=C-) form between the -OH groups of HA nanoparticles, the -OH groups of carboxymethyl chitosan, and -NH2 and the -OH groups of carbomer, providing connectivity. These non-covalent interactions contribute to the formation of the gel system. Furthermore, by adjusting the ratio and concentration of the three components to maintain the zeta point within the range of ±30–±60 mV, agglomeration is avoided, improving the viscoelastic and rheological properties of the aqueous system.

[0016] As a preferred technical solution of the present invention, in S1, the mass fraction of the NaOH solution is 0.5-8wt.%, for example, it can be 0.5wt.%, 1.25wt.%, 2.0wt.%, 2.75wt.%, 3.5wt.%, 4.25wt.%, 5.0wt.%, 5.75wt.%, 6.5wt.%, 7.25wt.% or 8.0wt.%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0017] In some optional examples, the molecular weight of the sodium hyaluronate powder is 10-50KDa, for example, 10KDa, 14KDa, 18KDa, 22KDa, 26KDa, 30KDa, 34KDa, 38KDa, 42KDa, 46KDa or 50KDa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] In some optional examples, the volume mass ratio of the NaOH solution, 1,4-butanediol diglycidyl ether and sodium hyaluronate powder is (58-300) mL: (0.12-9.83) g: (14-57) g, for example, it can be (58, 82.2, 106.4, 130.6, 154.8, 179, 203.2, 227.4, 251.6, 275.8 or 300) mL: (0. 12, 1.091, 2.062, 3.033, 4.004, 4.975, 5.946, 6.917, 7.888, 8.859 or 9.83) g: (14, 18.3, 22.6, 26.9, 31.2, 35.5, 39.8, 44.1, 48.4, 52.7 or 57) g, but are not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0019] In some optional embodiments, the temperature of the water bath is 24-26°C, for example, it can be 24.0°C, 24.2°C, 24.4°C, 24.6°C, 24.8°C, 25.0°C, 25.2°C, 25.4°C, 25.6°C, 25.8°C or 26.0°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In some optional examples, the water bath reaction time is 16-17 hours, for example, it can be 16.0 hours, 16.1 hours, 16.2 hours, 16.3 hours, 16.4 hours, 16.5 hours, 16.6 hours, 16.7 hours, 16.8 hours, 16.9 hours or 17.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In some optional examples, the dialysis is performed 5 times, and the phosphate dialysis solution is replaced every 4 hours.

[0022] In some optional examples, the particle size range of the HA nanoparticles is 20 nm-870 nm, for example, it can be 20 nm, 105 nm, 190 nm, 275 nm, 360 nm, 445 nm, 530 nm, 615 nm, 700 nm, 785 nm or 870 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] As a preferred technical solution of the present invention, in S2, the mass fraction of the carboxymethyl chitosan solution is 0.5-4.2wt.%, for example, it can be 0.5wt.%, 0.87wt.%, 1.24wt.%, 1.61wt.%, 1.98wt.%, 2.35wt.%, 2.72wt.%, 3.09wt.%, 3.46wt.%, 3.83wt.% or 4.2wt.%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In some optional examples, the molecular weight of carboxymethyl chitosan in the carboxymethyl chitosan solution is 50-300 kDa, for example, it can be 50 kDa, 75 kDa, 100 kDa, 125 kDa, 150 kDa, 175 kDa, 200 kDa, 225 kDa, 250 kDa, 275 kDa or 300 kDa, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0025] In some optional examples, the mass ratio of the carboxymethyl chitosan solution, 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and the catalyst is 100:(0.5-0.6):(0.6-0.7), for example, it can be 100:(0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59 or 0.6):(0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69 or 0.7), but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] In some optional examples, the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of (1-5):1, for example, (1.0, 1.4, 1.8, 2.2, 2.6, 3.0, 3.4, 3.8, 4.2, 4.6 or 5.0):1, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0027] As a preferred technical solution of the present invention, in S3, the mass ratio of the carboxymethyl chitosan gel, carbomer, HA nanoparticles and physiological saline is (0.13-6.8): (0.4-8.4): (0.8-9.2): (50-136), for example, it can be (0.13, 0.797, 1.464, 2.131, 2.798, 3.465, 4.132, 4.799, 5.466, 6.133 or 6.8): (0.4, 1.2, 2.0, 2.8, 3.6, 4.4, 5.2, 6.0, 6.8, 7.6 or 8.4): (0.8, 1.64, 2.48, 3.32, 4.16, 5.0, 5.84, 6.68, 7.52, 8.36 or 9.2): (50, 58.6, 67.2, 75.8, 84.4, 93, 101.6, 110.2, 118.8, 127.4 or 136), but are not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0028] In some optional examples, the molecular weight of the carbomer is 10-100 kDa, for example, it can be 10 kDa, 19 kDa, 28 kDa, 37 kDa, 46 kDa, 55 kDa, 64 kDa, 73 kDa, 82 kDa, 91 kDa or 100 kDa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In a second aspect, the present invention provides an oral ulcer gel dressing prepared by the preparation method described in the first aspect.

[0030] In a third aspect, an oral ulcer gel dressing prepared by the preparation method described in the first aspect is used to load minocycline hydrochloride, chlorhexidine gluconate, clindamycin hydrochloride, diclofenac sodium and metronidazole drugs.

[0031] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention selects low molecular weight HA with short molecular chain, large free volume at the end, and small size of network unit formed after cross-linking; the granulation is repeated in a granulator and ultrasonic crushing is used to obtain uniform nanoparticles; (2) 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid is used to react with carboxymethyl chitosan amino groups to introduce sulfide bonds into the carboxymethyl chitosan gel, which can regulate drug release in the presence of active oxygen; (3) Hyaluronic acid nanoparticles carry a large number of hydroxyl groups and negatively charged carboxyl groups, and carboxymethyl chitosan gel carries a large number of amide groups and positively charged amino groups. Through the attraction of positive and negative charges and the action of hydrogen bonds, the nanoparticles act as "cross-linking points" and the carboxymethyl chitosan polymer chains act as "bridges" to self-assemble into a continuous three-dimensional network. (4) When applying the gel, the gel is subjected to shear stress, electrostatic attraction and hydrogen bonds are destroyed, the gel network structure temporarily disintegrates (cross-linking points separate), the viscosity decreases, the gel becomes thinner, and the gel is evenly dispersed on the wound surface. After the application is completed, the molecular thermal motion causes the electrostatic attraction and hydrogen bonds to reform, the three-dimensional network of the gel is restored, the viscosity increases, and the adhesion residence time of the gel in the mouth is increased; (5) When oral ulcers or inflammation occur, immune cells such as neutrophils and macrophages will be activated, and a large amount of reactive oxygen species (ROS) will be produced through the NADPH oxidase system. After the gel is loaded with antibacterial and anti-inflammatory drugs, the thioether bonds in the gel that contacts the wound surface are broken under the action of reactive oxygen species (ROS), causing the drug to be gradually released from the inside to the outside, achieving sustained drug release and targeted treatment, prolonging the drug residence time, and improving the treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a particle size distribution diagram of HA nanoparticles provided in Example 1 of the present invention;

[0033] Figure 2 This is a SEM image of HA nanoparticles provided in Example 1 of the present invention;

[0034] Figure 3 This is a SEM image of the oral ulcer gel dressing provided in Example 1 of the present invention;

[0035] Figure 4 This is a SEM image of the oral ulcer gel dressing provided in Comparative Example 1 of the present invention;

[0036] Figure 5 A comparison chart of adhesion time test results between Example 1 of the present invention and Comparative Example 1 (A is Comparative Example 1, B is Example 1);

[0037] Figure 6 1 is a comparison chart of the cohesion test results of Example 1 of the present invention and Comparative Example 1 (A is Comparative Example 1, B is Example 1). DETAILED DESCRIPTION

[0038] The technical solutions of the present application will be described in detail below with reference to specific embodiments and the accompanying drawings. The embodiments described herein are specific embodiments of the present application, which are used to illustrate the concept of the present application; all the descriptions are explanatory and exemplary, and should not be construed as limiting the embodiments of the present application and the protection scope of the present application. In addition to the embodiments described herein, those skilled in the art can also employ other technical solutions that are obvious based on the content disclosed in the claims and the description of the present application, which include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0039] The chemical reagents used in the embodiments and comparative examples of the present application are all commercially available and are not subjected to any further purification treatment.

[0040] Example 1

[0041] The present embodiment provides an oral ulcer gel dressing and a preparation method thereof, which specifically comprises the following steps:

[0042] S1, 58 mL of 0.5 wt.% NaOH solution is mixed with 0.12 g of 1,4-butanediol diglycidyl ether, and then 14 g of sodium hyaluronate powder is added and stirred uniformly. The mixture is reacted in a 24℃ water bath for 16 h and dialyzed for 5 times, and the phosphate dialysis solution is replaced every 4 hours. A gel is obtained, which is then poured into a gel granulator for cyclic extrusion and ultrasonic pulverization to obtain HA nanoparticles.

[0043] S2, 100 g of 0.5 wt.% carboxymethyl chitosan solution is mixed with 0.5 g of 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and 0.6 g of catalyst is added for reaction. The molecular weight of carboxymethyl chitosan in the carboxymethyl chitosan solution is 50 kDa, and the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide with a mass ratio of 1:1. A carboxymethyl chitosan gel is obtained.

[0044] S3, 0.13 g of carboxymethyl chitosan gel, 0.4 g of 10 kDa carbomer, and 0.8 g of HA nanoparticles are added to 50 g of physiological saline to obtain an oral ulcer gel dressing.

[0045] Figure 1 The figure is the particle size distribution graph of the HA nanoparticles of the present embodiment. The average particle size is 414.2 nm, and the distribution coefficient is 0.58, indicating that the particle size distribution of the HA nanoparticles is uniform. Figure 2 The figure is the SEM graph of the HA nanoparticles of the present embodiment, indicating that the HA nanoparticles are uniformly distributed. Figure 3 The figure is the SEM graph of the oral ulcer gel dressing, and the pore structure is relatively compact.

[0046] Example 2

[0047] This embodiment provides an oral ulcer gel dressing and a preparation method thereof, wherein the preparation method specifically comprises the following steps:

[0048] S1: Mix 300 mL of 8 wt.% NaOH solution with 9.83 g of 1,4-butanediol diglycidyl ether, add 57 g of sodium hyaluronate powder, stir evenly, react in a 25°C water bath for 17 h, and dialyze five times, replacing the phosphate dialysis solution every four hours to obtain a gel. Pour the gel into a gel granulator for cyclic extrusion and ultrasonic crushing to obtain HA nanoparticles.

[0049] S2, mixing 100 g of a 4.2 wt.% carboxymethyl chitosan solution with 0.6 g of 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and adding 0.63 g of a catalyst for reaction, wherein the molecular weight of the carboxymethyl chitosan in the carboxymethyl chitosan solution is 300 kDa, and the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of 5:1, to obtain a carboxymethyl chitosan gel;

[0050] S3, 6.8 g of carboxymethyl chitosan gel, 8.4 g of 100 kDa carbomer and 9.2 g of HA nanoparticles were added to 136 g of normal saline and dispersed evenly to obtain an oral ulcer gel dressing.

[0051] Example 3

[0052] This embodiment provides an oral ulcer gel dressing and a preparation method thereof, wherein the preparation method specifically comprises the following steps:

[0053] S1: Mix 100 mL of 1 wt.% NaOH solution with 0.43 g of 1,4-butanediol diglycidyl ether, add 36.4 g of sodium hyaluronate powder, stir evenly, react in a 26°C water bath for 16.3 h, and dialyze five times, replacing the phosphate dialysis solution every four hours to obtain a gel. Pour the gel into a gel granulator for cyclic extrusion and ultrasonic crushing to obtain HA nanoparticles.

[0054] S2, mixing 100 g of a 2 wt.% carboxymethyl chitosan solution with 0.53 g of 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and adding 0.7 g of a catalyst for reaction, wherein the molecular weight of the carboxymethyl chitosan in the carboxymethyl chitosan solution is 300 kDa, and the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of 2:1, to obtain a carboxymethyl chitosan gel;

[0055] S3, 0.5 g of carboxymethyl chitosan gel, 0.5 g of 70 kDa carbomer and 1.9 g of HA nanoparticles were added to 96 g of normal saline and dispersed evenly to obtain an oral ulcer gel dressing.

[0056] Example 4

[0057] This embodiment provides an oral ulcer gel dressing and a preparation method thereof, wherein the preparation method specifically comprises the following steps:

[0058] S1: Mix 200 mL of 5 wt.% NaOH solution with 2.5 g of 1,4-butanediol diglycidyl ether, add 40 g of sodium hyaluronate powder, stir evenly, react in a 24°C water bath for 16.8 h, and dialyze five times, replacing the phosphate dialysis solution every four hours to obtain a gel. Pour the gel into a gel granulator for cyclic extrusion and ultrasonic crushing to obtain HA nanoparticles.

[0059] S2, mixing 100 g of a 3 wt.% carboxymethyl chitosan solution with 0.57 g of 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and adding 0.68 g of a catalyst for reaction, wherein the molecular weight of the carboxymethyl chitosan in the carboxymethyl chitosan solution is 200 kDa, and the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of 4:1, to obtain a carboxymethyl chitosan gel;

[0060] S3, 5 g of carboxymethyl chitosan gel, 4 g of 50 kDa carbomer and 6 g of HA nanoparticles were added to 80 g of normal saline and dispersed evenly to obtain an oral ulcer gel dressing.

[0061] Comparative Example 1

[0062] This comparative example provides an oral ulcer gel dressing and a preparation method thereof. The difference between the comparative example and Example 1 is that the mass of HA nanoparticles in S3 is 0, and the other process parameters and operating conditions are exactly the same as those in Example 1. Figure 4 This is the SEM image of the oral ulcer gel dressing in this comparative example, and the pore structure is relatively loose.

[0063] Comparative Example 2

[0064] This comparative example provides an oral ulcer gel dressing and a preparation method thereof. The difference between the comparative example and Example 1 is that the mass of carbomer in S3 is 0, and the other process parameters and operating conditions are exactly the same as those in Example 1.

[0065] Comparative Example 3

[0066] This comparative example provides an oral ulcer gel dressing and a preparation method thereof. The difference between the comparative example and Example 1 is that the mass of the carboxymethyl chitosan gel in S3 is 0, and the other process parameters and operating conditions are exactly the same as those in Example 1.

[0067] Zeta potential test method: Take oral ulcer gel dressing, dilute it 10 times with normal saline, turn on the Zeta potential instrument (Malvern Zetasizer Nano ZS), and add the oral ulcer gel dressing dispersed with a pipette into the measuring cell.

[0068] Adhesion strength test method: The adhesion performance of the hydrogel was tested using a pigskin shear tensile test. Fresh pigskin was selected, the fat inside the pigskin was cleaned, and then it was cut into 2.5×15 cm strips for later use. An appropriate amount of hydrogel was applied to the pigskin, and then another piece of pigskin was used to cover the pigskin coated with hydrogel, with a contact area of ​​2.5×2.5 cm. The sample was pulled at a speed of 5 mm / min using a tensile tester until the hydrogel separated from the pigskin. The maximum load at the time of separation was measured, and the shear adhesion strength (KPa) was obtained by dividing the maximum load by the contact area. Each sample was tested 5 times, and the average value was taken.

[0069] Washout resistance test method: Human skin is used for testing the adhesion of oral ulcer gel dressings to human skin. The oral ulcer gel dressing is applied to the surface of the human skin. Rapid water flow at different angles is used to vigorously impact the hydrogel on the human skin surface until all the gel is washed away. The adhesion time is recorded.

[0070] Antibacterial test method: Use a sterile cotton swab to apply the prepared Streptococcus mutans solution to an agar plate and spread evenly. Use a sterile pipette to draw up 50-100 μL of gel and drop it directly onto the center of the agar surface, forming a circular area. Each sample is tested three times for each bacterium. Each plate is incubated at 37°C for 48 hours. The diameter of the inhibition zone on each plate is measured using a vernier caliper. To eliminate bias, a normal saline solution control is used as a blank.

[0071] Cohesion test method: Dye the oral ulcer gel dressing and inject it into water. Then observe the changes in its morphology after it swells with water flow and is flushed by the water column.

[0072] The results of Zeta potential, adhesion strength, scour resistance and antibacterial tests are shown in Table 1.

[0073] Table 1 Test results of a gel dressing for oral ulcers in Examples 1-4, Comparative Examples 1-3 and a blank group (normal saline)

[0074]

[0075] As shown in Table 1, compared to Example 1, the adhesion strength and adhesion time of Comparative Example 1 were both reduced; the adhesion strength and adhesion time of Comparative Example 2 were both reduced; and the adhesion strength, adhesion time, and antibacterial effect of Comparative Example 3 were all reduced. Sodium hyaluronate is a highly hydrophilic and high-molecular-weight polysaccharide. Its molecular chains contain a large number of hydroxyl and carboxyl groups, which can enhance the three-dimensional network structure of the gel through hydrogen bonding and electrostatic interactions. In Comparative Example 1, the mass of the HA nanoparticles was zero, resulting in reduced adhesion strength and adhesion time. Figure 4 This is the SEM image of the oral ulcer gel dressing of comparative example 1, compared with the SEM image of the oral ulcer gel dressing of example 1 ( Figure 3 ), the three-dimensional structure is relatively loose. Figure 5 This is a comparison chart of the adhesion time test results of Example 1 and Comparative Example 1 (A is Comparative Example 1, B is Example 1). It can be clearly seen that under the impact of water flow, the gel of Comparative Example 1 has been separated from the skin surface, but the gel of Example 1 still has a good adhesion effect. Figure 6 This is a comparison chart of the cohesion test results of Example 1 of the present invention and Comparative Example 1 (A is Comparative Example 1, B is Example 1). Comparative Example 1 lacks HA nanoparticles and has poor cohesion. It disintegrates and disperses after being flushed by a water column in water. Example 1 still retains its shape after being flushed in water and has better cohesion.

[0076] Carbomer has abundant carboxyl functional groups. The lack of carbomer will lead to a significant decrease in the viscoelasticity and thickening ability of the gel, and the cross-linking density of the three-dimensional network structure will be weakened. Therefore, the adhesion strength and adhesion time of Comparative Example 2 are both reduced. The mass of carboxymethyl chitosan in Comparative Example 3 is 0. Carboxymethyl chitosan can interact with glycoproteins on the surface of the oral mucosa through hydrogen bonds and electrostatic effects, thereby enhancing the adhesion of the gel to the mucosa. At the same time, carboxymethyl chitosan has natural antibacterial activity and a broad antibacterial spectrum. It has an antibacterial effect on dental plaque bacteria such as oral mutans Streptococcus, resulting in a decrease in the adhesion strength, adhesion time and antibacterial effect of Comparative Example 3.

[0077] The following is a biocompatibility test of the oral ulcer gel dressing prepared in Example 1.

[0078] Biocompatibility is generally evaluated through in vitro and in vivo testing methods and approaches, such as cytology, histology, and immunology, to study the interaction between medical materials and organisms, thereby evaluating the safety of the final product and minimizing clinical risks. Based on the product's characteristics and intended site of use, and in accordance with the GB / T 16886 "Biological Evaluation of Medical Devices" standard, the oral ulcer gel dressing prepared in Example 1 was subjected to biosafety evaluation using cytotoxicity, skin sensitization, and skin irritation tests.

[0079] Cytotoxicity assay:

[0080] Sample Extraction: A sample of the oral ulcer gel dressing prepared in Example 1 was collected under sterile conditions and extracted by shaking in a sealed inert container according to the extraction ratio (sample: extraction medium) specified in Table 2 below. The extraction medium was MEM culture medium containing 10% fetal bovine serum. No significant changes were observed between the test sample (the oral ulcer gel dressing prepared in Example 1) and the extract before and after the extraction. The extract was not pH-adjusted and was not filtered, centrifuged, or diluted.

[0081] Table 2 Extraction conditions

[0082]

[0083] Experimental Procedure: Aseptic manipulation was performed during the experiment. L929 cells were cultured in MEM medium containing 1% fetal bovine serum and antibiotics (penicillin 100 U / mL, streptomycin 100 μg / L) in a 37°C, 5% CO2 incubator. The cells were digested with 0.25% trypsin (containing EDTA) to prepare a single-cell suspension. The cell suspension was centrifuged (200g, 3 minutes) and the cells were redispersed in the culture medium. The cell concentration was adjusted to 1x10 5 100 μL of the cell suspension was inoculated into a 96-well culture plate, and the plates were incubated in a 37°C incubator (5% CO2, >90% humidity) for 24 hours. After the cells grew into a monolayer after 24 hours of culture, the cell growth status in the 96-well culture plate was observed under a microscope to ensure that the cell proliferation in each well was relatively equal. The original culture medium was then aspirated, and 100 μL of different concentrations of test sample extracts (100%, 50%, 25%, 12.5%), blank control solution, positive control (100%), and negative control solution (100%) were added, and the plates were then incubated in a 37°C incubator (5% CO2, 37°C, >90% humidity) for 24 hours. Five replicates were prepared for each group. After 24 hours of culture, the 96-well plates were removed and cell morphology was observed under a microscope. The original culture medium was then aspirated, and 50 μL of MTT (1 mg / mL) was added to each well. The cells were incubated in a 37°C incubator (5% CO2, 37°C, >90% humidity) for 2 hours. The supernatant was discarded, and 100 μL of 99.9% pure isopropanol was added to dissolve the crystals. The absorbance was measured on a microplate reader at a primary absorption wavelength of 570 nm and a reference wavelength of 650 nm. Cell viability was calculated using the following formula: Cell viability (%) = 100 * (OD570 of the test sample group / OD570 of the blank group)

[0084] Results: The cell viability of the 100% extract group of the test sample was 97.1%, with no cytotoxicity. Detailed results are shown in Tables 3 and 4.

[0085] Table 3 Cell morphology observation

[0086]

[0087] Table 4 Cell viability

[0088]

[0089] Skin sensitization test:

[0090] Experimental Procedure: Fifteen healthy male albino guinea pigs, weighing 300-500g, were randomly divided into a test group of 10 and a control group of 5. The test sample (the oral ulcer gel dressing prepared in Example 1) was applied topically to induce a skin sensitization reaction. The control group also underwent a similar local induction procedure. After induction, the test and control groups were challenged with the corresponding sample. Skin reactions at the challenged sites in the test and control groups were observed 24 and 48 hours after removal of the test sample (the oral ulcer gel dressing prepared in Example 1). Skin erythema and edema reactions were scored at each challenge site and at each observation time according to the Magnusson and Kligman grading system listed in Table 5.

[0091] Table 5 Magnusson and Kligman classification

[0092]

[0093] Observation Results: 24 ± 2 hours and 48 ± 2 hours after removal of the test sample (the oral ulcer gel dressing prepared in Example 1) from the test sample group and the control group, the skin conditions at the provocation site were observed under full-spectrum light. Guinea pigs were weighed and recorded within 48 hours of the final observation. Skin erythema and edema reactions at each provocation site and observation time were described and graded according to the Magnusson and Kligman grading scale in the table below.

[0094] Experimental Results: The results of post-challenge skin reactions are listed in Table 6. The test sample (the oral ulcer gel dressing prepared in Example 1) did not induce skin sensitization in guinea pigs, with a positive sensitization rate of 0%. The positive control group had a sensitization rate of 100%. Under these experimental conditions, the test sample (the oral ulcer gel dressing prepared in Example 1) showed no evidence of skin sensitization in guinea pigs.

[0095] Table 6 Guinea pig skin sensitization reaction of the test sample (oral ulcer gel dressing prepared in Example 1)

[0096]

[0097] Skin irritation test:

[0098] Test Procedure: Three healthy female New Zealand albino rabbits weighing >2.0 kg were selected. A test sample (the oral ulcer gel dressing prepared in Example 1) was applied to both sides of the back of the healthy animals, measuring 2.5 cm x 2.5 cm and no more than 0.5 cm thick. A similarly sized medical gauze patch soaked in 0.9% sodium chloride injection was applied to the control area. Skin reactions at each contact site were observed 1 hour, 24 hours, 48 ​​hours, and 72 hours after removal of the dressing. Skin erythema and edema reactions at each contact site during each specified time period were scored according to the scoring system in Table 7, and the primary irritation index was calculated.

[0099] Table 7 Intradermal irritation response scoring system

[0100]

[0101] Result evaluation: Only observation data from (24 ± 2) h, (48 ± 2) h, and (72 + 2) h were used for calculation. The erythema and edema irritation scores for each animal at each specified time were added together and divided by the total number of observations, 15 (3 observation times x 5 injection points), to obtain the score for each animal. The average score of the three test animals was the mean score. Calculate the mean control score and subtract this score from the mean score of the test sample to obtain the difference in the mean scores. This value is the final score of the test sample. If the final score of the test sample is no greater than 1.0, it meets the test requirements.

[0102] Test results: No animals showed abnormal symptoms or died during the experiment. It was observed that the intradermal reactions of the test sample (the oral ulcer gel dressing prepared in Example 1) did not exceed those of the control group, and the final scores were all 0. See Table 8.

[0103] Table 8 Observation of intradermal irritation reaction results

[0104]

[0105] The drug loading and encapsulation efficiency are shown in Table 9.

[0106] Table 9 Encapsulation efficiency and loading rate of each drug in oral ulcer gel dressing

[0107]

[0108] The calculation formula of loading rate and encapsulation rate: loading rate = 100%,

[0109] Encapsulation efficiency = 100.

[0110] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an oral ulcer gel dressing, characterized in that: The preparation method comprises: S1, mixing NaOH solution with 1,4-butanediol diglycidyl ether, then adding sodium hyaluronate powder, stirring evenly, cross-linking to obtain a gel, dialyzing, and then cyclic granulation and ultrasonication to obtain HA nanoparticles; S2, mixing the carboxymethyl chitosan solution with 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, adding a catalyst, and reacting to obtain a carboxymethyl chitosan gel; S3, adding the carboxymethyl chitosan gel, carbomer and the HA nanoparticles into normal saline and dispersing them evenly to obtain an oral ulcer gel dressing; The catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, with a mass ratio of (1-5):

1.

2. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S1: The mass fraction of the NaOH solution is 0.5-8wt.%; The molecular weight of the sodium hyaluronate powder is 10-50Kda.

3. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S1: The volume-to-mass ratio of the NaOH solution, 1,4-butanediol diglycidyl ether, and sodium hyaluronate powder is (58-300) mL: (0.12-9.83) g: (14-57) g.

4. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S1: The dialysis was performed 5 times, with the phosphate dialysis solution being replaced every 4 hours.

5. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S1: The particle size of the HA nanoparticles ranges from 20 nm to 870 nm.

6. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S2: The mass fraction of the carboxymethyl chitosan solution is 0.5-4.2wt.%; The molecular weight of the carboxymethyl chitosan in the carboxymethyl chitosan solution is 50-300 kDa.

7. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S2: The mass ratio of the carboxymethyl chitosan solution, 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and the catalyst is 100:(0.5-0.6):(0.6-0.7); The catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, with a mass ratio of (1-5):

1.

8. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that: In S3: The mass ratio of the carboxymethyl chitosan gel, carbomer, HA nanoparticles and normal saline is (0.13-6.8): (0.4-8.4): (0.8-9.2): (50-136); The molecular weight of the carbomer is 10-100 kDa.

9. An oral ulcer gel dressing, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of an oral ulcer gel dressing obtained by the preparation method according to any one of claims 1 to 8 in loading minocycline hydrochloride, chlorhexidine gluconate, clindamycin hydrochloride, diclofenac sodium and metronidazole.

Images