An oral ulcer gel dressing, its preparation method and application

Abstract

The application belongs to the field of oral medical drugs, and provides an oral ulcer gel dressing, a preparation method and application thereof; the characteristics of high cross-linking particle type sodium hyaluronate are used to reduce the water absorption and swelling of the product, and the synergistic effect of micro-nano level hyaluronic acid particles and high molecules endows the gel with the shear thinning characteristics of non-Newtonian fluid; in the static state, the gel shows high adhesion and can firmly cover the oral mucosa wound surface; when being applied or external force being applied, the viscosity is significantly reduced, so that more convenient operability and distribution uniformity are realized; the high molecular material further enhances the thickening performance and biological adhesion of the gel, so that the gel can be closely combined with the oral mucosa surface, and also provides multiple functions such as antibiosis, moisturizing and healing promotion, and is suitable for the treatment and nursing of oral ulcer and other mucosa injuries.

Description

TECHNICAL FIELD

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

[0002] Oral ulcer, commonly known as "apthous ulcer", is a common ulcerative injury disease occurring in oral mucosa. It is estimated that about 10% of the population in China will have recurrent oral ulcer. In addition to drug treatment or vitamin supplementation, gels made of hydrophilic polymer biomaterials such as chitosan, sodium hyaluronate and carbomer are widely used in clinical practice to relieve the pain of oral ulcer and accelerate the recovery of the lesion site. The high-molecular material covers the lesion area of the oral mucosa and forms a film, which can protect the wound and prevent bacterial infection. The stable polymer film can also provide a biological scaffold for the growth of normal cells, thereby accelerating the directional proliferation of epithelial cells and shortening the healing process of the ulcer. However, the currently marketed products have high water absorption, swell rapidly after absorbing saliva in the oral cavity, and the viscosity of the material decreases, making it difficult to stay in the ulcer site for a long time, thus greatly reducing the treatment effect. At the same time, considering the diversification of ulcer sites, including the tongue, periodontal, buccal, soft palate and other sites, the gel needs to have strong fluidity to be more easily applied to cover different shaped wounds.

[0003] The existing drugs for treating oral ulcer or oral inflammation are usually directly applied or pasted on the wound. Due to the humid environment in the oral cavity, the drug has a short residence time and poor treatment effect. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide an oral ulcer gel dressing and a preparation method and application thereof. The sodium hyaluronate is prepared into nanoparticles, and then self-assembled with carboxymethyl chitosan and carbomer gel to form a nanogel dressing. The nanogel has the characteristic of shear thinning, so that the viscosity decreases when applying, making the gel uniformly dispersed and covering the wound tissue. After application, the viscosity rises, improving the adhesion time of the gel. The carboxymethyl chitosan and carbomer endow the gel with excellent thickening performance and biological adhesion, ensuring that it can adhere to the wound surface for a long time in the humid environment of the oral cavity. The sodium hyaluronate and carboxymethyl chitosan have a large number of carboxyl, amino and hydroxyl groups, which can load a variety of antibacterial and anti-inflammatory drugs through electrostatic interaction, hydrogen bonding and other interactions. The thioether bond in carboxymethyl chitosan is broken when it contacts with active oxygen, so that the drug is gradually released, prolonging the residence time of the drug in the oral cavity and improving the treatment effect.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a preparation method of 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 uniformly, crosslinking to obtain a gel, dialysis, and obtaining HA nanoparticles through circulation granulation and ultrasonic treatment;

[0008] S2, mixing 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 the carboxymethyl chitosan gel, carbomer, and HA nanoparticles into physiological saline, and uniformly dispersing to obtain an oral ulcer gel dressing.

[0010] Specifically comprising:

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

[0012] S2, mixing 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 the carboxymethyl chitosan gel, carbomer, and HA nanoparticles into physiological saline, and uniformly dispersing to obtain an oral ulcer gel dressing.

[0014] NaOH solution was mixed with 1,4-butanediol diglycidyl ether, which is a bifunctional epoxy compound containing active epoxy groups in its molecular structure. Epoxy groups are prone to nucleophilic ring-opening reactions under basic conditions, thus crosslinking with nucleophilic groups (such as hydroxyl and carboxyl groups) in other molecules. NaOH not only acts as a basic regulator in the solution, but also promotes the reactivity by increasing the electrophilicity of the epoxy groups. Subsequently, sodium hyaluronate powder was introduced into the above reaction system. Sodium hyaluronate is a biologically active macromolecular polysaccharide containing a large number of hydroxyl and carboxyl groups in its molecular chain. In a basic environment, the carboxyl group ionizes to form a carboxylate, while the hydroxyl group acts as the main nucleophile and undergoes nucleophilic addition reaction with the epoxy group of 1,4-butanediol diglycidyl ether. The crosslinking reaction leads to the formation of a three-dimensional interpenetrating network structure between the molecular chains of sodium hyaluronate through covalent bonds. The formation of this crosslinked structure significantly improves the mechanical strength, water absorption and stability of the gel. The obtained gel crude product was subjected to multiple cycles of extrusion and ultrasonic treatment by a gel granulator to obtain nanoparticles. HA nanoparticles have high specific surface area and excellent dispersibility, which can significantly improve the uniformity and functionality of the material in subsequent preparation process. In addition, HA nanoparticles retain the hygroscopicity and biological activity of sodium hyaluronate, and can play an important role in oral ulcer dressings, including promoting ulcer healing, improving material flowability and prolonging residence time in the lesion site.

[0015] Carboxymethyl chitosan reacts with 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid in the presence of catalyst EDC·HCl and NHS to generate carboxymethyl chitosan gel containing a sulfide bond. Carboxymethyl chitosan is a natural polymer with both negative and positive charges, and its molecules contain a large number of hydroxyl (-OH), amino (-NH3) and carboxyl (-COOH) functional groups, which can form a stable complex system with other components in aqueous solution through intermolecular hydrogen bonding and electrostatic interaction. Carbomer is a high molecular weight acrylic polymer with a large number of carboxyl groups (-COOH) in its molecular chain, which can ionize to produce negative charges in aqueous solution to form a network structure with good thickening and gelling capacity. HA nanoparticles are a highly hydrophilic material with hydroxyl (-OH) and carboxyl (-COOH) groups on their surface, which can form a stable complex system with other components in aqueous solution through intermolecular hydrogen bonding and electrostatic interaction. However, if the concentration of the components is too low, the distance between the particles is too large, and the non-covalent interaction (hydrogen bonding, electrostatic) is not enough to drive self-assembly, the system is a dispersed nanosuspension without network structure; if the concentration is too high, the particles are too crowded, and local charge imbalance can easily lead to agglomeration, resulting in a sudden increase in viscosity but poor uniformity; by adjusting the proportion and concentration of the above three components, HA nanoparticles are used as crosslinking points, and carboxymethyl chitosan and carbomer are used as "bridges" to construct a continuous three-dimensional network structure formed by multiple forces, such as electrostatic attraction between -COO- and -NH3+, hydrogen bonding between -OH of HA nanoparticles, -OH and -NH2 of carboxymethyl chitosan, and -OH of carbomer (such as -OH…O=C-), which provides connection for the network; the non-covalent interaction between these components participates in the construction of the gel system. In addition, by adjusting the proportion of the three and the concentration of each component, the Zeta point of the system is controlled in the range of ±30~±60mV, which avoids agglomeration and improves the viscoelastic properties and rheological properties of the aqueous phase system.

[0016] As a preferred technical solution of the present application, 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 range are also applicable.

[0017] In some optional examples, the sodium hyaluronate powder has a molecular weight of 10-50 Kda, for example, can be 10 Kda, 14 Kda, 18 Kda, 22 Kda, 26 Kda, 30 Kda, 34 Kda, 38 Kda, 42 Kda, 46 Kda or 50 Kda, but not only limited to the listed values, other values not listed in the 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, 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 not only limited to the listed values, other values not listed in the range are also applicable.

[0019] In some optional examples, the temperature of the water bath is 24-26℃, for example, can be 24.0℃, 24.2℃, 24.4℃, 24.6℃, 24.8℃, 25.0℃, 25.2℃, 25.4℃, 25.6℃, 25.8℃ or 26.0℃, but not only limited to the listed values, other values not listed in the range are also applicable.

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

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

[0022] In some optional examples, the HA nanoparticles have a particle size ranging from 20 nm to 870 nm, such as 20 nm, 105 nm, 190 nm, 275 nm, 360 nm, 445 nm, 530 nm, 615 nm, 700 nm, 785 nm or 870 nm, but not limited to the listed values, and other values not listed within the range are also applicable.

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

[0024] In some optional examples, the carboxymethyl chitosan in the carboxymethyl chitosan solution has a molecular weight of 50-300 kDa, such as 50 kDa, 75 kDa, 100 kDa, 125 kDa, 150 kDa, 175 kDa, 200 kDa, 225 kDa, 250 kDa, 275 kDa or 300 kDa, but not limited to the listed values, and other values not listed within the 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), such as 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 not limited to the listed values, and other values not listed within the range are also applicable.

[0026] In some optional examples, the catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, and the mass ratio is (1-5): 1, such as (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 not limited to the listed values, and other values not listed within the range are also applicable.

[0027] As a preferred technical solution of the present application, 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 not limited to the listed values, other values not listed in the 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 not limited to the listed values, other values not listed in the range are also applicable.

[0029] In the second aspect, the present application provides an oral ulcer gel dressing prepared by the preparation method of the first aspect.

[0030] In the third aspect, the application of the oral ulcer gel dressing prepared by the preparation method of the first aspect to load minocycline hydrochloride, chlorhexidine gluconate, clindamycin hydrochloride, diclofenac sodium and metronidazole drugs.

[0031] Compared with the prior art, the application has the following beneficial effects: (1) the application selects low molecular weight HA, the molecular chain is short, the terminal free volume is large, and the network unit size formed after crosslinking is small; uniform nanoparticles are obtained through multiple cycle granulation of a granulator and ultrasonic crushing; (2) 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid is used for condensation reaction with the carboxymethyl chitosan amino, a thioether bond is introduced into the carboxymethyl chitosan gel, and the drug release can be regulated in the presence of active oxygen; (3) the hyaluronic acid nanoparticles have a large number of hydroxyl groups and negative charge carboxyl groups, the carboxymethyl chitosan gel has a large number of amide groups and positive charge amino groups, through the attraction of positive and negative charges and the hydrogen bond effect, the nanoparticles serve as the “crosslinking point”, the carboxymethyl chitosan polymer chain serves as the “bridge”, and a continuous three-dimensional network gel with shear thinning characteristics is self-assembled; (4) when the gel is applied, the gel is subjected to shear stress, the electrostatic attraction and the hydrogen bond are destroyed, the gel network structure is temporarily disintegrated (the crosslinking points are separated), the viscosity is reduced, and the gel is thinned, so that the gel is uniformly dispersed on the wound surface, after the application is completed, the electrostatic attraction and the hydrogen bond are reformed due to molecular thermal motion, the three-dimensional network of the gel is restored, the viscosity is increased, and the adhesion residence time of the gel in the oral cavity is improved; (5) when oral ulcer or inflammation occurs, immune cells such as neutrophils and macrophages are activated, a large amount of active oxygen ROS is generated through the NADPH oxidase system, after the gel is loaded with antibacterial and anti-inflammatory drugs, the thioether bond in the gel contacting the wound is broken under the action of active oxygen ROS, so that the drugs are gradually released from the inside to the outside, the drug sustained release and targeted treatment are realized, the drug residence time is prolonged, and the treatment effect is improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The HA nanoparticle particle size distribution diagram provided for the embodiment 1 of the application;

[0033] Figure 2 The HA nanoparticle SEM diagram provided for the embodiment 1 of the application;

[0034] Figure 3 The oral ulcer gel dressing SEM diagram provided for the embodiment 1 of the application;

[0035] Figure 4 The oral ulcer gel dressing SEM diagram provided for the comparative example 1 of the application;

[0036] Figure 5 The adhesion time test effect comparison diagram of the embodiment 1 and the comparative example 1 of the application (A is the comparative example 1, and B is the embodiment 1);

[0037] Figure 6 The cohesion test effect comparison diagram of the embodiment 1 and the comparative example 1 of the application (A is the comparative example 1, and B is the embodiment 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 specification 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, with the phosphate dialysis solution being 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 then 0.6 g of catalyst is added for reaction. The carboxymethyl chitosan in the carboxymethyl chitosan solution has a molecular weight of 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 a dispersion, thereby obtaining an oral ulcer gel dressing.

[0045] Figure 1 The figure is a 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 a SEM graph of the HA nanoparticles of the present embodiment, indicating that the HA nanoparticles are uniformly distributed. Figure 3 The figure is a SEM graph of the oral ulcer gel dressing, and the pore structure is relatively compact.

[0046] Example 2

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

[0048] S1, 300 mL, 8 wt.% NaOH solution was mixed with 9.83 g of 1,4-butanediol diglycidyl ether, then 57 g of sodium hyaluronate powder was added and stirred uniformly, reacted in a water bath at 25°C for 17 h and dialyzed for 5 times, and the phosphate dialysis solution was replaced every 4 hours to obtain a gel, which was poured into a gel granulator for cyclic extrusion and then ultrasonic pulverization to obtain HA nanoparticles;

[0049] S2, 100 g, 4.2 wt.% carboxymethyl chitosan solution was mixed with 0.6 g of 3,3'-(propane-2,2-diylbis(sulfanediyl))dipropionic acid, and 0.63 g of catalyst was added for reaction, the molecular weight of carboxymethyl chitosan in the carboxymethyl chitosan solution was 300 kDa, and the catalyst was a mixture of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide with 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 uniformly dispersed to obtain an oral ulcer gel dressing.

[0051] Example 3

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

[0053] S1, 100 mL, 1 wt.% NaOH solution was mixed with 0.43 g of 1,4-butanediol diglycidyl ether, then 36.4 g of sodium hyaluronate powder was added and stirred uniformly, reacted in a water bath at 26°C for 16.3 h and dialyzed for 5 times, and the phosphate dialysis solution was replaced every 4 hours to obtain a gel, which was poured into a gel granulator for cyclic extrusion and then ultrasonic pulverization to obtain HA nanoparticles;

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

[0055] S3, 0.5 g carboxymethyl chitosan gel, 0.5 g, 70 kDa carbomer and 1.9 g HA nanoparticles were added into 96 g normal saline, and a mouth ulcer gel dressing was obtained after uniform dispersion.

[0056] Example 4

[0057] The present example provides a mouth ulcer gel dressing and a preparation method thereof, and the preparation method specifically comprises the following steps:

[0058] S1, 200 mL of 5 wt.% NaOH solution was mixed with 2.5 g of 1,4-butanediol diglycidyl ether, and then 40 g of sodium hyaluronate powder was added and stirred uniformly. The mixture was reacted in a water bath at 24°C for 16.8 h and dialyzed for 5 times, and the phosphate dialysis solution was replaced every 4 hours. A gel was obtained, which was then poured into a gel granulator for cyclic extrusion and ultrasonic crushing to obtain HA nanoparticles;

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

[0060] S3, 5 g of carboxymethyl chitosan gel, 4 g of 50 kDa carbomer and 6 g of HA nanoparticles were added into 80 g of normal saline, and a mouth ulcer gel dressing was obtained after uniform dispersion.

[0061] Comparative Example 1

[0062] The present comparative example provides a mouth ulcer gel dressing and a preparation method thereof, which is different from Example 1 in that the mass of HA nanoparticles in S3 is 0, and the other process parameters and operating conditions are exactly the same as those of Example 1. Figure 4 The SEM image of the mouth ulcer gel dressing of the present comparative example shows a relatively loose pore structure.

[0063] Comparative Example 2

[0064] The present comparative example provides a mouth ulcer gel dressing and a preparation method thereof, which is different from Example 1 in that the mass of carbomer in S3 is 0, and the other process parameters and operating conditions are exactly the same as those of Example 1.

[0065] Comparative Example 3

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

[0067] Zeta potential test method: take the oral ulcer gel dressing, use physiological saline to dilute 10 times, open the Zeta potential instrument (Malvern Zetasizer Nano ZS), and use the dispensing pipette to add the prepared oral ulcer gel dressing into the measuring pool.

[0068] Adhesion strength test method: the adhesion performance of the hydrogel is tested by using pig skin shear tensile test. Fresh pig skin is selected, the fat in the inner layer of the pig skin is cleaned, and then the pig skin is cut into 2.5*15 cm strips for standby. A proper amount of hydrogel is applied on the pig skin, and then another piece of pig skin is covered on the pig skin with hydrogel, the contact area is 2.5*2.5 cm. A tensile tester is used to pull the sample at a speed of 5 mm / min until the hydrogel separates from the pig skin. The maximum load at the time of separation is measured, and the shear adhesion strength (KPa) is obtained by dividing the maximum load by the contact area. Each sample is tested 5 times, and the average value is taken.

[0069] Erosion resistance test method: human skin is selected for testing, which is used to test the adhesion of the oral ulcer gel dressing on human skin. The oral ulcer gel dressing is applied to the surface of human skin, and a rapid water flow at different angles is used to impact the hydrogel on the surface of human skin until all the gel is washed away. The adhesion time is recorded.

[0070] Bacteriostatic test method: a sterile cotton swab is used to dip the prepared Streptococcus mutans liquid, and the agar plate is evenly dried. 50-100 μL of gel is sucked with a sterile pipette, and is directly dropped on the center of the agar surface to form a circular area. Each sample is repeated 3 times for each bacterium. Each plate is placed in a 37℃ incubator for 48h, and the diameter of the bacteriostatic ring on each plate is measured with a vernier caliper. To eliminate errors, physiological saline is used as a blank group.

[0071] Cohesiveness test method: the oral ulcer gel dressing is dyed and then injected into water, and then the swelling and water column flushing of the water flow are observed to observe the morphological changes.

[0072] The results of Zeta potential, adhesion strength, erosion resistance and bacteriostatic test are shown in Table 1.

[0073] Table 1: Test results of oral ulcer gel dressing of examples 1-4, comparative examples 1-3 and blank group (physiological saline)

[0074]

[0075] From Table 1, compared with Example 1, the adhesion strength and adhesion time of Comparative Example 1 are reduced; the adhesion strength and adhesion time of Comparative Example 2 are reduced; the adhesion strength, adhesion time and antibacterial effect of Comparative Example 3 are reduced. Sodium hyaluronate is a polysaccharide with strong hydrophilicity and high molecular weight, which contains a large number of hydroxyl and carboxyl groups in the molecular chain, and can enhance the three-dimensional network structure of the gel through hydrogen bond and electrostatic interaction. In Comparative Example 1, the mass of HA nanoparticles is 0, and the adhesion strength and adhesion time are reduced. Figure 4 The SEM image of the oral ulcer gel dressing of Comparative Example 1 is shown in the figure, compared with the SEM image of the oral ulcer gel dressing of Example 1 (Figure Figure 3 ), the three-dimensional structure is relatively loose. Figure 5 The adhesion time test effect comparison chart of Example 1 and Comparative Example 1 (A is Comparative Example 1, B is Example 1) can clearly see 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 good adhesion effect. Figure 6 The cohesion test effect comparison chart of Example 1 and Comparative Example 1 (A is Comparative Example 1, B is Example 1) is shown in the figure, Comparative Example 1 lacks HA nanoparticles, and the cohesion is poor. After being washed by the water column in water, it is disintegrated and dispersed. Example 1 still retains its shape after being washed in water, and has good cohesion.

[0076] Carbomer has rich carboxyl functional groups, and the lack of carbomer will cause the viscoelasticity and thickening ability of the gel to decrease significantly, and the crosslinking density of the three-dimensional network structure to weaken, so the adhesion strength and adhesion time of Comparative Example 2 are reduced. In Comparative Example 3, the mass of carboxymethyl chitosan is 0. Carboxymethyl chitosan can interact with the glycoprotein on the surface of oral mucosa through hydrogen bond and electrostatic interaction, and enhance the adhesion between the gel and the mucosa. At the same time, carboxymethyl chitosan has natural antibacterial activity, and has a broad antibacterial spectrum, which has an antibacterial effect on dental plaque bacteria such as Streptococcus mutans, resulting in a decrease in the adhesion strength, adhesion time and antibacterial effect of Comparative Example 3.

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

[0078] Biocompatibility is generally studied by in vitro and in vivo test methods and means such as cytology, histology and immunology to study the interaction between medical materials and organisms, so as to evaluate the safety of the final product and minimize the clinical risk. According to the product characteristics and the use site, the cytotoxicity, skin sensitization and skin irritation tests are selected according to the GB / T 16886 series standards for biological evaluation of medical devices to evaluate the biological safety of the oral ulcer gel dressing prepared in Example 1.

[0079] Cytotoxicity test:

[0080] Sample extraction: The oral ulcer gel dressing prepared in Example 1 was sampled under sterile conditions and extracted in a closed inert container with shaking at the extraction ratios (sample: extraction medium) shown in Table 2 below using MEM medium containing 10% fetal bovine serum as the extraction medium. The test sample (oral ulcer gel dressing prepared in Example 1) and the extraction medium were not significantly changed before and after extraction. The extraction medium was not adjusted in pH, and was not filtered, centrifuged or diluted.

[0081] Table 2 Extraction conditions

[0082]

[0083] Test procedure: The 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, which was centrifuged (200 G, 3 min) and then the cells were redispersed in culture medium to adjust the cell concentration to 1x10 5 The cell suspension was inoculated into a 96-well culture plate at 100 μL per well, and incubated in a 37°C incubator (5% CO2, >90% humidity) for 24 h. After the cells had grown into a monolayer, the growth of the cells in the 96-well culture plate was observed under a microscope to ensure that the cells in each well had proliferated relatively equally. The original culture medium was then removed, and 100 μL of different concentrations of test sample extraction liquid (100%, 50%, 25%, 12.5%), blank control liquid, positive control (100%) and negative control liquid (100%) were added, respectively, and then incubated in a 37°C incubator (5% CO2, 37°C, >90% humidity) for 24 h. Five parallel samples were prepared for each group. After 24 h of incubation, the 96-well plate was removed and the cell morphology was observed under a microscope. The original culture medium was then removed, and 50 μL of MTT (1 mg / mL) was added to each well, which was then incubated in a 37°C incubator (5% CO2, 37°C, >90% humidity) for 2 h. The supernatant was then removed, and 100 μL of 99.9% pure isopropyl alcohol was added to dissolve the crystals. The absorbance value was measured on an enzyme marker instrument at a main absorption wavelength of 570 nm and a reference wavelength of 650 nm. The cell viability value was calculated according to the following formula: cell viability (%) = 100 * (OD570 test sample group / OD570 blank group)

[0084] Results: The cell viability value of the 100% extraction liquid of the test sample was 97.1%, and there was no cytotoxicity. The specific 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] Test Procedure: 15 healthy male albino guinea pigs, weighing 300-500 g, were selected and randomly divided into groups. 10 in the test group and 5 in the control group. The test sample (oral ulcer gel dressing prepared in Example 1) was respectively closed for local induction to produce skin sensitization reaction. The control group was also locally induced in the same way. After induction, the test group and the control group were applied with the corresponding sample for challenge. 24 h and 48 h after removing the test sample (oral ulcer gel dressing prepared in Example 1), the skin reaction at the challenge site of the test group and the control group was observed, and the skin erythema and edema reaction at each challenge site and each observation time were scored according to the Magnusson and Kligman grading standard.

[0091] Table 5 Magnusson and Kligman Grading

[0092]

[0093] Observation of Results: (24±2) h and (48±2) h after removing the test sample (oral ulcer gel dressing prepared in Example 1), the skin condition at the challenge site of the test sample group (oral ulcer gel dressing prepared in Example 1) and the control group was observed, the skin reaction was observed under full spectrum light, and the guinea pigs were weighed and recorded within 48 hours after the last observation. The skin erythema and edema reaction at each challenge site and each observation time were described and graded according to the Magnusson and Kligman grading standard as shown in the table below.

[0094] Experimental Results: The skin reaction results after challenge are shown in Table 6. No skin sensitization reaction was found in the test sample (oral ulcer gel dressing prepared in Example 1) in guinea pigs, and the sensitization positive rate was 0%. The sensitization positive rate of the positive control group was 100%. Under the conditions of this test, there was no evidence that the test sample (oral ulcer gel dressing prepared in Example 1) caused skin sensitization reaction in guinea pigs.

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

[0096]

[0097] Skin Irritation Test:

[0098] Test procedure: 3 healthy female New Zealand white rabbits, body weight > 2.0 kg, were selected. The test sample (oral ulcer gel dressing prepared in Example 1) was applied to the back of the healthy animals on both sides, with a size of 2.5 cm*2.5 cm and a thickness of not more than 0.5 cm. The same size of medical gauze soaked with 0.9% sodium chloride injection was applied to the control site. After removing the application, the skin reaction of each contact site was observed at 1 h and 24 h, 48 h, 72 h, and the skin erythema and edema reaction of each contact site at each specified time was described and scored according to the scoring system in Table 7, and the primary irritation index was calculated.

[0099] Table 7 Scoring system for intracutaneous irritation reaction

[0100]

[0101] Result evaluation: Only the observation data at (24±2) h, (48±2) h and (72±2) h were used for calculation. The sum of the erythema and edema irritation scores of each animal at each specified time was divided by the total number of observations, 15 (3 observation times x 5 injection points), to obtain the score of each animal. The average of the scores of the three test animals was the average score. The average score of the control was subtracted from the average score of the test sample to obtain the difference in average score. This value was the final score of the test sample. If the final score of the test sample was not greater than 1.0, it met the test requirements.

[0102] Test results: During the experiment, the animals showed no abnormal symptoms or death, and it was observed that the intracutaneous reaction of the test sample (oral ulcer gel dressing prepared in Example 1) did not exceed that of the control group, and the final score was 0. See Table 8.

[0103] Table 8 Results of intracutaneous irritation reaction observation

[0104]

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

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

[0107]

[0108] The formula for calculating the loading rate and the encapsulation rate is: loading rate = 100%,

[0109] encapsulation rate = 100.

[0110] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and all such changes and replacements fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing an oral ulcer gel dressing, characterized in that, The preparation method includes: S1, NaOH solution is mixed with 1,4-butanediol diglycidyl ether, and sodium hyaluronate powder is added. The mixture is stirred evenly, crosslinked to obtain a gel, dialyzed, and then granulated by circulation and sonicated to obtain HA nanoparticles. S2, a carboxymethyl chitosan solution is mixed with 3,3'-(propane-2,2-diylbis(thioalkyldiyl))dipropionic acid, a catalyst is added, and the reaction is carried out to obtain carboxymethyl chitosan gel; S3, the carboxymethyl chitosan gel, carbomer and HA nanoparticles are added to physiological saline and dispersed evenly to obtain an oral ulcer gel dressing; The catalyst is a mixture of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide in 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 NaOH solution has a mass fraction of 0.5-8 wt.%. The molecular weight of the sodium hyaluronate powder is 10-50 kDa.

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 procedure consisted of 5 dialysis sessions, with the phosphate dialysis solution being changed 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 range of the HA nanoparticles is 20nm-870nm.

6. The method for preparing an oral ulcer gel dressing according to claim 1, characterized in that, In S2: The carboxymethyl chitosan solution has a mass fraction of 0.5-4.2 wt.%. The molecular weight of 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(thionidyl))dipropionic acid, and 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 in 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 to physiological 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. A gel dressing for oral ulcers, characterized in that, Obtained by the preparation method according to any one of claims 1-8.

10. The use of an oral ulcer gel dressing obtained by the preparation method according to any one of claims 1-8 in a drug loaded with minocycline hydrochloride, chlorhexidine gluconate, clindamycin hydrochloride, diclofenac sodium and metronidazole.

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