Bacterial cellulose injectable gel and preparation method thereof

Abstract

The invention relates to the field of biomedicine, in particular to bacterial cellulose injectable gel and a preparation method thereof. The bacterial cellulose injectable gel comprises the following components: 1-5% of sulfonated bacterial cellulose dispersion liquid, 3-5% of sodium alginate, 1-3% of an ionic water-retaining agent, 0.1-1% of a cross-linking agent and the balance of water, the ion water-retaining agent comprises one or more of polylysine, chitosan and sodium carboxymethyl cellulose. In order to solve the problems of insufficient water-retaining property, controllable degradability and biocompatibility of the existing injectable gel, the prepared bacterial cellulose injectable gel is uniform and stable, so that the formed gel has the excellent effects of good supporting property, difficulty in flowing and controllable degradation. The prepared injectable gel has the advantages of high water binding capacity and strength, no foreign matters during degradation, good compatibility and no irritation, so that the prepared injectable gel is kept in a stable state within a relatively long time and is not degraded, and frequent injection is not needed.

Description

Technical Field

[0001] The present application relates to the biomedical field, and in particular to an injectable bacterial cellulose gel and a preparation method thereof. Background Art

[0002] With the deepening integration of biomedicine and aesthetic medicine, modern aesthetic medicine is placing higher demands on the biocompatibility, degradation controllability, and functionality of soft tissue support materials. Traditional soft tissue support materials, such as hyaluronic acid and botulinum toxin, can enhance skin elasticity and improve skin rejuvenation through minimally invasive injections. However, their short biodegradation cycle (typically less than three months) makes them difficult to meet the long-term requirements for soft tissue repair and skin rejuvenation interventions. Furthermore, frequent interventions increase the risks of clinical application. While synthetic polymer materials based on polylactic acid and polycaprolactone have been shown to extend their effectiveness to over a year through microsphere dispersion technology, the mismatch between the degradation cycle of synthetic polymers and the metabolic rate of human tissue leads to frequent biocompatibility issues such as chronic inflammatory reactions and foreign body granulomas, posing a serious challenge to the long-term safety of these materials. Achieving long-term soft tissue support while ensuring material biocompatibility has become a pressing issue in the field. Bacterial cellulose, a natural nanofiber material with a high degree of supramolecular homology to the human dermal matrix, possesses excellent tissue affinity and controlled degradability (degradation cycle of approximately 9 months). However, its mechanical properties in its natural state are insufficient to meet the viscoelastic requirements of an injectable gel. Furthermore, the three-dimensional nanostructure of the bacterial cellulose hydrogel itself lacks good water-repellent and water-retaining properties, and its high water vapor permeability makes it prone to water loss during use. These issues have hindered the application of bacterial cellulose injectable gels. There is an urgent need to develop a new soft tissue support material that combines biosafety, long-term tissue repair capabilities, and injectable operability. Summary of the Invention

[0003] In order to solve the problems of insufficient water retention, controllable degradability and biocompatibility of existing injectable gels, and their inability to achieve both biosafety, long-term tissue repair function and injectable operability, the present application provides a bacterial cellulose injectable gel and a preparation method thereof.

[0004] In a first aspect, the present application provides a bacterial cellulose injectable gel, which adopts the following technical solution: A bacterial cellulose injectable gel comprises the following components by weight: 1-5% sulfonated bacterial cellulose dispersion, 3-5% sodium alginate, 1-3% ionic water-retaining agent, 0.1-1% cross-linking agent, and the remainder water; the ionic water-retaining agent comprises one or more of polylysine, chitosan, and sodium carboxymethyl cellulose.

[0005] Through this technical solution, bacterial cellulose is structurally homologous to the dermal matrix, avoiding foreign body reactions with synthetic polymers. Sulfonation partially hydrolyzes the β-1,4 glycosidic bonds of the bacterial cellulose, reducing fiber crystallinity and improving its dispersibility, thus preventing uneven mechanical properties caused by fiber aggregation after gel injection. Sulfonate groups also bind to enzyme active sites through hydrogen bonds, delaying cellulase hydrolysis of bacterial cellulose and enabling precise regulation of the degradation cycle. The crosslinker triggers the formation of sodium alginate gel, building a primary pre-crosslinked network that imparts gel-forming capabilities and uniform distribution, ensuring a stable morphology after injection, enhancing its mechanical properties, and providing a certain degree of water retention. Polylysine acts as an ionic water-retaining agent. Its amino groups cross-link with sodium alginate and sulfonated bacterial cellulose via amide bonds, forming a secondary network that significantly enhances the long-term mechanical stability of the gel and slows degradation. It also increases the degree of cross-linking in the hydrogel and prolongs its degradation cycle, allowing the resulting injectable gel to remain stable and undegraded for extended periods, significantly extending its useful life and eliminating the need for frequent injections. Furthermore, electrostatic attraction between its cationic amino groups and the anionic carboxyl groups of sodium carboxymethylcellulose enhances the stability of the gel network. Sodium carboxymethylcellulose forms a physical cross-linked network with other active hydroxyl groups through hydrogen bonding and electrostatic interactions, further enhancing the gel's water retention and prolonging its degradation cycle. Furthermore, the interaction of these components ensures uniform distribution of the gel, improving the support and viscosity of the injectable gel, resulting in a gel that exhibits excellent support, resistance to flow, and superior viscosity. To solve the problems of insufficient water retention, controlled degradability and biocompatibility of existing injectable gels, the injectable gel of the present application has high water retention, high tensile strength, good skin compatibility, and is non-irritating, and has both biosafety, long-term tissue repair function and injectable operability.

[0006] In a specific embodiment, the preparation method of sodium alginate includes: adding sodium alginate powder to MES buffer, adding EDC / NHS in an ice bath at 0-4°C, stirring and activating for 15-30 minutes, then adding ethylenediamine dropwise, adjusting the temperature to 25-30°C and reacting for 6-8 hours to obtain sodium alginate.

[0007] Preferably, the mass ratio of sodium alginate to ethylenediamine is 1:(0.4-0.5).

[0008] The mass ratio of the sulfonated bacterial cellulose dispersion, sodium alginate and ionic water-retaining agent is 1:(3-5):1.

[0009] Through the above technical solution, sodium alginate is modified with specific functional groups to form chemical bonds or interactions with amide bonds, forming active functional groups such as amino groups, and constructing a synergistic cross-linking network. This breaks through the limitations of low strength of traditional electrostatic interactions, allowing the compound to maintain structural integrity in blood and normal tissues, avoiding premature degradation or failure, improving compressive strength, and enhancing elasticity and stability. After injection into the human body, the gel is highly uniform, maintaining facial elasticity, remaining stable for a long time, and not being degraded, extending the degradation time of the injectable gel and eliminating the need for frequent injections. Excessive ethylenediamine content reduces the water retention of the gel. In addition, the sulfonated bacterial cellulose dispersion, sodium alginate, and ionic water-retaining agent within the scope of this application can further coordinate the interactions between the various components, achieving a better balance between the water retention, degradation cycle, and product viscosity of the gel. Excessive sodium alginate will affect the mechanical tensile strength of the injectable gel and reduce elasticity and other properties. Too little sodium alginate will reduce the adsorption and binding properties of water molecules, leading to excessive water loss and reduced water retention.

[0010] In a specific embodiment, the polylysine is modified polylysine, and its preparation method includes: dissolving dextran in water, stirring, slowly adding sodium periodate in the dark, stirring and reacting for 3-4 hours, adding ethylene glycol, continuing to stir, dialyzing with water to obtain oxidized dextran, adding water, stirring and adjusting the pH to 7-7.5, adding polylysine, stirring and letting stand, and freeze-drying to obtain modified polylysine.

[0011] The mass ratio of the oxidized dextran to polylysine is (2-3):1.

[0012] The above technical solution, prepared by oxidizing dextran, generates aldehyde groups that react rapidly with some amino groups of polylysine under neutral conditions to form dynamic, reversible Schiff base bonds, giving the gel self-healing ability. The three-dimensional structure of the Schiff base network can effectively lock in moisture. During injection, the material is subjected to shear force, temporarily breaking the dynamic cross-links. After injection, the shear force disappears, the cross-links reform, and the material returns to a solid or gel state, localized at the injection site to fill and support tissue. In addition, oxidized dextran and polylysine have low immunogenicity, and the aldehyde-amino reaction has no toxic byproducts, resulting in good biocompatibility. Therefore, the aldehyde content can regulate the degradation rate of the material, allowing the dynamic Schiff base bonds to be hydrolyzed more slowly by tissue fluid, thereby slowing the degradation rate, avoiding a sudden increase in the degradation rate, and reducing the probability of inflammation and other risks. Excessive oxidized dextran may lead to an overly compact gel structure, reduced elasticity, and unfavorable for controlled degradation. The excessive hydrophilic groups also increase water vapor permeability, which in turn reduces water retention. Excessive polylysine causes excessive local cross-linking of the gel, poor stability, reduced elasticity, and affects the degradation rate.

[0013] Preferably, the ionic water-retaining agent is modified polylysine and sodium carboxymethyl cellulose in a mass ratio of (3-5):1.

[0014] Through the above technical solution, modified polylysine provides compatibility and amino reaction sites; the hydroxyl groups of oxidized dextran form numerous hydrogen bonds with the carboxyl groups of sodium carboxymethylcellulose, creating electrostatic attraction between the cationic amino groups of polylysine and the anionic carboxyl groups of sodium carboxymethylcellulose, enhancing mechanical strength and water retention. Hydrogen bonds and electrostatic interactions form a physical cross-linked network that locks in moisture, improving water retention. The polymer chains of dextran can form an interpenetrating network through hydrogen bonds, enhancing the elastic modulus and deformation resistance of the gel. Dynamic Schiff base bonds can be slowly hydrolyzed by tissue fluid, enabling controlled degradation, and the aldehyde content can regulate the material's degradation rate. The hydrophilic groups of dextran can absorb water molecules, reducing the "graininess" of the injected gel and making the skin feel more natural after filling, making it particularly suitable for filling superficial fine lines. Sodium carboxymethylcellulose generates multiple charge interactions with the gel, enhancing the stability of the gel network. If the proportion of sodium carboxymethylcellulose is too high, the gel may become too rigid, reducing its elasticity and adaptability. If the proportion of sodium carboxymethylcellulose is too low, its effectiveness in enhancing the gel's mechanical strength and water retention decreases, affecting the regulation of the gel's degradation rate.

[0015] In a specific embodiment, the cross-linking agent is a calcium chloride solution.

[0016] In a second aspect, the present application provides a method for preparing an injectable bacterial cellulose gel, which adopts the following technical solution: A method for preparing a bacterial cellulose injectable gel comprises the following steps: S1: Add the bacterial cellulose dispersion into concentrated sulfuric acid pre-cooled to 0-5°C, stir in an ice-water bath for 1-2 hours, slowly heat to 50-60°C for reaction for 1-2 hours, and dialyze in water for 36-48 hours to obtain sulfonated bacterial cellulose solution; S2: dissolving sodium alginate in water to prepare a sodium alginate solution with a concentration of 6-11 wt%; S3: Add the ionic water retaining agent into water and stir for 10-15 minutes to obtain an ionic water retaining agent solution; S4: adding the sodium alginate solution obtained in step S2 and the ionic water-retaining agent solution to the sulfonated bacterial cellulose dispersion, and then adding the cross-linking agent, stirring and mixing, and storing at 4-5° C. to obtain a bacterial cellulose injectable gel.

[0017] In step S4, the stirring and mixing is carried out at a speed of 200-300 r / min for 25-30 min.

[0018] In summary, this application includes at least one of the following beneficial technical effects: 1. Enhanced mechanical properties and stability. The cross-linker triggers the rapid gelation of sodium alginate to form a primary network, which gives it instant molding ability. The polylysine plasma water-retaining agent and sodium alginate / sulfonated cross-linking construct a secondary covalent network to improve long-term mechanical stability. The polymer chain of the polylysine-modified dextran forms a network interpenetrating structure through hydrogen bonds to improve the elastic modulus and deformation resistance. The interaction between sodium alginate and sulfonated bacterial cellulose can improve the compressive strength. Polylysine produces multiple charge interactions with sodium alginate and sulfonated bacterial cellulose to enhance the stability of the gel network.

[0019] 2. Modified polylysine provides compatibility and amino reaction sites; a large number of hydrogen bonds are formed between the hydroxyl groups of oxidized dextran and the carboxyl groups of sodium carboxymethyl cellulose, and there is electrostatic attraction between the cationic amino groups of polylysine and the anionic carboxyl groups of sodium carboxymethyl cellulose, which enhances the mechanical strength and water retention. A physical cross-linked network is formed through hydrogen bonds and electrostatic interactions to lock in moisture, thereby improving the water retention rate. The polymer chains of dextran can form a network interpenetrating structure through hydrogen bonds, thereby improving the elastic modulus and deformation resistance of the gel; the dynamic Schiff base bonds can be slowly hydrolyzed by tissue fluid to achieve controllable degradation, so that controlling the aldehyde content can adjust the degradation rate of the material; the hydrophilic groups of dextran can adsorb water molecules, avoiding the "graininess" of the injected gel, making the skin feel more natural after filling, especially suitable for filling superficial fine lines. DETAILED DESCRIPTION

[0020] Some of the raw materials used in the preparation examples and embodiments: Sodium alginate powder: Jiangsu Dongju Biotechnology Co., Ltd.; MES buffer product number: M885673, purchased from Maclean; bacterial cellulose dispersion TL-008: Nanjing Tianlu Nanotechnology Co., Ltd.; polylysine 99%: Maclean; dextran Mw, 10000: product number D992645; Maclean; calcium chloride solution: 1M calcium chloride solution, prepared by anhydrous calcium chloride and water.

[0021] The raw materials used in the examples and comparative examples that are not otherwise specified are all conventional products that can be purchased from the market.

[0022] Preparation Example 1 The preparation method of modified polylysine includes: dissolving 5g of dextran in 100ml of water, stirring for 15-20 minutes, slowly adding 3.2g of sodium periodate in the dark, stirring and reacting for 4h, adding 5ml of ethylene glycol, continuing to stir for 1h, dialyzing with water for 72h, changing the water every 8h, filtering, and freeze-drying to obtain oxidized dextran, taking 1g of oxidized dextran and adding 10ml of water, stirring, adjusting the pH to 7 with 0.1M NaOH, adding 0.5g of polylysine, adjusting the pH to 7 with 0.1M HCl, stirring, standing, and freeze-drying to obtain modified polylysine.

[0023] Preparation Example 2 The preparation method of modified polylysine includes: dissolving 5g of dextran in 100ml of water, stirring for 15-20 minutes, slowly adding 3.2g of sodium periodate in the dark, stirring and reacting for 4h, adding 5ml of ethylene glycol, continuing to stir for 1h, dialyzing with water for 72h, changing the water every 8h, filtering, and freeze-drying to obtain oxidized dextran, taking 1.2g of oxidized dextran and adding 10ml of water, stirring, adjusting the pH to 7 with 0.1M NaOH, adding 0.3g of polylysine, adjusting the pH to 7 with 0.1M HCl, stirring, standing, and freeze-drying to obtain modified polylysine.

[0024] Preparation Example 3 The preparation method of modified polylysine includes: dissolving 5g of dextran in 100ml of water, stirring for 15-20 minutes, slowly adding 3.2g of sodium periodate in the dark, stirring and reacting for 4 hours, adding 5ml of ethylene glycol, continuing to stir for 1 hour, dialyzing with water for 72 hours, changing the water every 8 hours, filtering, and freeze-drying to obtain oxidized dextran, taking 0.75g of oxidized dextran and adding it to 10ml of water, stirring, adjusting the pH to 7 with 0.1M NaOH, adding 0.75g of polylysine, adjusting the pH to 7 with 0.1M HCl, stirring, standing, and freeze-drying to obtain modified polylysine.

[0025] Preparation Example 4 The preparation method of sodium alginate includes: adding 1 g of sodium alginate powder to 100 ml of 0.1 M MES buffer, stirring evenly, adding 0.12 g of EDC and 0.09 g of NHS in an ice bath at 4° C., stirring and activating for 30 minutes, then dropwise adding 0.5 g of ethylenediamine, adjusting the temperature to 30° C. to react for 8 hours, dialyzing for 72 hours, changing the water every 8 hours, and freeze-drying to obtain sodium alginate.

[0026] Preparation Example 5 The preparation method of sodium alginate includes: adding 1 g of sodium alginate powder to 100 ml of 0.8 M MES buffer, stirring evenly, adding 0.12 g of EDC and 0.09 g of NHS in an ice bath at 4° C., stirring and activating for 30 minutes, then dropwise adding 0.7 g of ethylenediamine, adjusting the temperature to 30° C. to react for 8 hours, dialyzing for 72 hours, changing the water every 8 hours, and freeze-drying to obtain sodium alginate. Example 1

[0027] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine obtained in Preparation Example 1; and the cross-linking agent is calcium chloride. The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 2

[0028] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine obtained in Preparation Example 1 and sodium carboxymethyl cellulose in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 3

[0029] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine and sodium carboxymethyl cellulose obtained in Preparation Example 1 in a mass ratio of 3:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 4

[0030] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine and sodium carboxymethyl cellulose obtained in Preparation Example 1 in a mass ratio of 3:3; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 5

[0031] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine and sodium carboxymethyl cellulose obtained in Preparation Example 2 in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 6

[0032] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is modified polylysine and sodium carboxymethyl cellulose obtained in Preparation Example 3 in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 7

[0033] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 5, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine and sodium carboxymethyl cellulose obtained in Preparation Example 1 in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid pre-cooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, and replacing water every 8 hours to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 5 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water and stirring for 15 minutes to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a cross-linking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain a bacterial cellulose injectable gel. Example 8

[0034] A bacterial cellulose injectable gel, comprising: 5 g of sulfonated bacterial cellulose dispersion, 40 g of sodium alginate obtained in Preparation Example 4, 5 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine obtained in Preparation Example 1 and sodium carboxymethyl cellulose in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 9

[0035] A bacterial cellulose injectable gel, comprising: 15 g of sulfonated bacterial cellulose dispersion, 20 g of sodium alginate obtained in Preparation Example 4, 15 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine obtained in Preparation Example 1 and sodium carboxymethyl cellulose in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 10

[0036] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine and sodium carboxymethyl cellulose prepared in Preparation Example 1 in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid pre-cooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving sodium alginate powder in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 into the sulfonated bacterial cellulose dispersion, then adding a cross-linking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 11

[0037] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is polylysine and sodium carboxymethyl cellulose in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel. Example 12

[0038] A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is polylysine with a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding an ionic water-retaining agent into 100 ml of water, stirring for 15 minutes, to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a crosslinking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain an injectable bacterial cellulose gel.

[0039] Comparative Example 1 A bacterial cellulose injectable gel, comprising: 10 g of bacterial cellulose dispersion, 30 g of sodium alginate obtained in Preparation Example 4, 10 g of an ionic water-retaining agent, 4 g of a cross-linking agent, and water to make up to 1000 g; the ionic water-retaining agent is the modified polylysine obtained in Preparation Example 1 and sodium carboxymethyl cellulose in a mass ratio of 5:1; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion liquid to 100 ml of water and mixing to obtain a bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8 wt%; S3: adding an ionic water-retaining agent to 100 ml of water and stirring for 15 minutes to obtain an ionic water-retaining agent solution; S4: adding the sodium alginate solution and the ionic water-retaining agent solution obtained in step S2 to the bacterial cellulose dispersion liquid, then adding a cross-linking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4°C to obtain a bacterial cellulose injectable gel.

[0040] Comparative Example 2 A bacterial cellulose injectable gel, comprising: 10 g of sulfonated bacterial cellulose dispersion, 40 g of sodium alginate obtained in Preparation Example 4, 4 g of a cross-linking agent, and water to make up to 1000 g; the cross-linking agent is calcium chloride; The preparation method comprises the following steps: S1: adding a bacterial cellulose dispersion into 100 ml of 50% concentrated sulfuric acid precooled to 5° C., stirring for 1 hour in an ice-water bath, slowly heating to 60° C. for reaction for 2 hours, dialyzing in water for 48 hours, replacing water every 8 hours, to obtain a sulfonated bacterial cellulose liquid; S2: dissolving the sodium alginate obtained in Preparation Example 4 in water to obtain a sodium alginate solution with a concentration of 8wt%; S3: adding the sodium alginate solution obtained in step S2 to the sulfonated bacterial cellulose dispersion, then adding a cross-linking agent, supplementing water in proportion, stirring at a speed of 300 r / min for 30 minutes, and storing at 4° C. to obtain a bacterial cellulose injectable gel.

[0041] 1. Water retention rate: Place the bacterial cellulose injectable gel in a constant temperature and humidity environment at 25°C (room temperature) and 50% RH (relative humidity). Calculate the initial weight of the bacterial cellulose injectable gel by weighing, and record it as W0 and the weight after 36 hours as W. 1， The ratio of W1 / W0 was calculated as the water retention rate; 2. In vitro degradation performance: The bacterial cellulose injectable gel was freeze-dried and weighed as m0, and placed in an aqueous solution containing 0.5wt% hydrogen peroxide. Degradation test was performed at 37°C in an air bath shaker at a shaking speed of 150rpm. Every 30 days, the sample was taken out, freeze-dried, and weighed as m1 (the weight obtained at this time was the m1 at that time point, i.e., the weight of the freeze-dried sample remaining after degradation). Then, new degradation solution was replaced. The degradation rate at different times was calculated as (m0-m1) / m0×100%. When (m0-m1 / m0)>0.99, it was completely degraded, and the degradation time was recorded. 3. Tensile strength: The tensile properties of the bacterial cellulose injectable gel were tested at room temperature using a CMT4102 universal testing machine. The specimen used in the tensile test had a diameter of 5 mm, a length of 30 mm, and a tensile rate of 5 mm / min. The results are shown in Table 1 below.

[0042] Table 1 Performance test results

[0043] The bacterial cellulose injectable gel is uniform and stable, improving its support and viscosity. This results in a gel with excellent support, resistance to flow, and controlled degradation. The high water retention and strength, the absence of foreign matter upon degradation, and its excellent compatibility and non-irritation ensure that the resulting injectable gel remains stable for extended periods without degradation, eliminating the need for frequent injections.

[0044] From comparative examples 2-4, it can be seen that a large number of hydrogen bonds are formed between the hydroxyl groups of oxidized dextran and the carboxyl groups of sodium carboxymethyl cellulose, thereby enhancing the mechanical strength and water retention. A physical cross-linked network is formed through hydrogen bonds and electrostatic interactions to lock in moisture, thereby improving the water retention rate. The polymer chains of dextran can form a network interpenetrating structure through hydrogen bonds, thereby improving the elastic modulus and deformation resistance of the gel. The dynamic Schiff base bonds can be slowly hydrolyzed by tissue fluid to achieve controllable degradation. The hydrophilic groups of dextran can adsorb water molecules, reduce the "graininess" of the injected gel, and make the skin feel more natural after filling, which is especially suitable for filling superficial fine lines. If the proportion of sodium carboxymethyl cellulose is too high, the rigidity of the gel may be too strong. If the sodium carboxymethyl cellulose is too little, its effective enhancement of the mechanical strength and water retention of the gel decreases, affecting the regulation of the gel degradation rate.

[0045] By comparing Examples 1-2 with Examples 11-12 and Comparative Example 2, it can be seen that the aldehyde groups produced by oxidized dextran react rapidly with the amino groups of polylysine under neutral conditions to form dynamically reversible Schiff base bonds, which can effectively lock in moisture and locate at the injection site to fill and support tissues. The aldehyde-amino reaction has no toxic byproducts and good biocompatibility. It can be hydrolyzed more slowly by tissue fluid, thereby slowing down the degradation rate, avoiding a sudden increase in the degradation rate, and reducing the probability of risks such as inflammation. Excessive oxidized dextran may cause the gel structure to be too tight and not conducive to controlled degradation. It may also increase the water vapor permeability due to excessive hydrophilic groups, which in turn reduces the water retention. Excessive polylysine causes excessive local cross-linking of the gel, poor stability, reduced elasticity, and affects the degradation rate.

[0046] Comparing Example 2 with Examples 5-7 and Examples 8-10 and Comparative Example 1, it can be seen that the crosslinker triggers sodium alginate to form a gel, constructing a primary pre-crosslinked network, ensuring stable morphology after injection and enhancing its mechanical properties. Polylysine, as an ionic water-retaining agent, is cross-linked with sodium alginate and sulfonated bacterial cellulose through amide bonds to construct a secondary network, significantly improving the long-term mechanical stability of the gel, so that the prepared injectable gel remains stable for a long time without degradation. Excessive ethylenediamine content reduces the water retention of the gel. Excessive sodium alginate will affect the mechanical tensile strength of the injectable gel, reduce elasticity and other properties. Too little sodium alginate will reduce the adsorption and binding properties of water molecules, thereby leading to excessive water loss and reduced water retention. Excessive polylysine significantly reduces tensile strength and shortens the complete degradation time, but the degradation rate is significantly accelerated over a period of time. The degradation rate is too slow at some times, and the degradation rate is unstable.

[0047] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

Claims

1. A bacterial cellulose injectable gel, characterized in that: The components include by weight: 1-5% sulfonated bacterial cellulose dispersion, 3-5% sodium alginate, 1-3% ionic water-retaining agent, 0.1-1% cross-linking agent, and the remainder is water; the ionic water-retaining agent includes one or more of polylysine, chitosan, and sodium carboxymethyl cellulose.

2. The bacterial cellulose injectable gel according to claim 1, characterized in that: The preparation method of sodium alginate comprises: adding sodium alginate powder into MES buffer, adding EDC / NHS in an ice bath at 0-4° C., stirring and activating for 15-30 minutes, then dropwise adding ethylenediamine, adjusting the temperature to 25-30° C., and reacting for 6-8 hours to obtain sodium alginate.

3. The bacterial cellulose injectable gel according to claim 1, characterized in that: The mass ratio of the sulfonated bacterial cellulose dispersion, sodium alginate and ionic water-retaining agent is 1:(3-5):

1.

4. The bacterial cellulose injectable gel according to claim 1, characterized in that: The polylysine is modified polylysine, and its preparation method includes: dissolving dextran in water, stirring, slowly adding sodium periodate in the dark, stirring and reacting for 3-4 hours, adding ethylene glycol, continuing stirring, dialyzing with water to obtain oxidized dextran, adding water, stirring, adjusting the pH to 7-7.5, adding polylysine, stirring, standing, and freeze-drying to obtain modified polylysine.

5. The bacterial cellulose injectable gel according to claim 4, characterized in that: The mass ratio of the oxidized dextran to polylysine is (2-3):

1.

6. The bacterial cellulose injectable gel according to claim 1, characterized in that: The cross-linking agent is calcium chloride solution.

7. The method for preparing a bacterial cellulose injectable gel according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Add the bacterial cellulose dispersion into concentrated sulfuric acid pre-cooled to 0-5°C, stir in an ice-water bath for 1-2 hours, slowly heat to 50-60°C for reaction for 1-2 hours, and dialyze in water for 36-48 hours to obtain sulfonated bacterial cellulose solution; S2: dissolving sodium alginate in water to prepare a sodium alginate solution with a concentration of 6-11 wt%; S3: Add the ionic water retaining agent into water and stir for 10-15 minutes to obtain an ionic water retaining agent solution; S4: adding the sodium alginate solution and ionic water-retaining agent solution obtained in step S2 and then adding a cross-linking agent to the sulfonated bacterial cellulose dispersion, stirring and mixing, and storing at 4-5° C. to obtain a bacterial cellulose injectable gel.

8. The method for preparing a bacterial cellulose injectable gel according to claim 7, characterized in that: In step S4, the stirring and mixing is carried out at a speed of 200-300 r / min for 25-30 min.

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