A mussel-inspired multifunctional dual-network crosslinked hydrogel wound dressing

Abstract

The application discloses a mussel-inspired multifunctional double-network crosslinked hydrogel wound dressing. A hydrogel network formed by dynamic covalent crosslinking between carboxymethyl chitosan and oxidized sodium alginate is utilized; further, a natural antioxidant, gallic acid, with a catechol structure is introduced to enhance the tightness of the hydrogel network combination and endow the hydrogel with certain adhesion and antioxidant properties; finally, a mussel adhesive fluid containing catechol and iron is imitated to have strong tissue adhesion behavior under alkaline conditions, which is suitable for dynamic wound treatment, so as to prepare a mussel-inspired multifunctional double-network crosslinked hydrogel wound dressing. In addition, catechol-Fe 3+ Metal coordination also shows strong antibacterial effect, and under the irradiation of near-infrared light, light energy can be converted into heat energy for preventing and treating wound infection, shortening wound closure time and preventing scar formation.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical materials, and in particular relates to a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing and a preparation method thereof. Background Art

[0002] As the largest organ in the human body, the skin plays a vital role in protecting the body from pathogen invasion and maintaining biological functions. However, the skin barrier is easily damaged due to trauma or disease, especially full-thickness wounds involving dermal defects, which are still a major problem in clinical care. In addition, due to the frequent movement of the active wound area (such as frequent stretching of joint wounds), traditional non-stretchable and non-self-healing wound dressings are easily damaged or fall off due to frequent movement. Hydrogels are considered to be the most promising wound dressings because they are composed of hydrophilic three-dimensional networks that can absorb tissue exudates, provide a breathable and moist environment for the wound, and accelerate wound healing. Therefore, hydrogel dressings designed with good tissue adhesion, stretchability and self-healing properties, which can adhere to the moving surface of the wound and adapt to frequent movement have good application prospects.

[0003] The self-healing behavior of hydrogels is mainly achieved through reversible physical non-covalent interactions and chemical covalent bonds. Physical cross-linking forms weaker bonds, but the bond formation and reconstruction of dynamic equilibrium are faster. The mechanical strength of physically cross-linked hydrogels is weak and not suitable for dynamic winding. Chemical cross-linking can form stronger bonds, but the bond formation and reconstruction of dynamic equilibrium are slower. Introducing chemical cross-linking is a method to improve the mechanical strength of hydrogels. Reversible imine bonds are a dynamic chemical covalent bond that is often used to trigger the preparation of injectable self-healing hydrogels. Inspired by mussels, catechol-based wet adhesives have attracted widespread attention in the past few years. Mussels secrete catechol and iron (Fe) at low pH (pH < 5). 3+ ) weak monocomplex adhesive solution, and the monocomplex was further transferred to seawater (pH increased to ∼8) to form di- or tri-complexes to enhance underwater adhesion. In addition, the materials containing catechol groups showed good biocompatibility and free radical scavenging ability, as well as good adhesion to Fe 3+ After complexation, it has photothermal capacity to inactivate bacteria, which is crucial for wound healing. Therefore, the research goal of this invention is to design a physicochemical double-crosslinked injectable self-healing hydrogel that integrates multiple functions, including strong tissue adhesion, inherent antibacterial activity and hemostasis.

[0004] At present, wound dressings based on catechol structures have been widely studied. Zhou et al. grafted catechol groups into the skeleton of carboxymethyl chitosan and combined it with modified sodium alginate to prepare a hydrogel dressing with strong adhesion properties. In the rabbit liver injury model, it also showed excellent hemostatic properties, with a blood loss of 0.32 g, which was only 54.2% of fibrin glue. Li et al. designed an injectable self-dual dynamic Schiff base hydrogel composed of modified hyaluronic acid and benzaldehyde polymer based on the similar catechol structure of melanin nanoparticles derived from cuttlefish juice, which can adapt to the frequent movement of sports wounds. The hydrogel dressing significantly prevented wound infection in the full-thickness wound model of animals and promoted wound healing through milder inflammation, higher granulation tissue thickness and collagen tendency. Liang et al. used iron (Fe 3+ ), catechol- and aldehyde-containing protocatechol (PA) and quaternized chitosan (QCS) by double dynamic bond crosslinking, a series of adhesive antioxidant and antibacterial self-healing hydrogels with good properties were designed to promote wound healing of methicillin-resistant Staphylococcus aureus (MRSA) infection. In addition, Yang et al. used catechol-modified oxidized hyaluronic acid and gelatin to form dynamic Schiff base bonds and then coordinate crosslinking Fe 3+ A double-crosslinked hydrogel was prepared, exhibiting enhanced mechanical properties, adhesive strength, and injectable self-healing ability, as well as excellent shape adaptability. It also significantly shortened the closure time of burn wounds in rats. Yu et al., through multiple weak hydrogen bonds and metal ligand coordination, used chitosan, silk fibroin, tannic acid (with a catechol structure), and iron ions to prepare a highly porous cryogel that exhibited excellent hygroscopicity and hemostasis. Animal experiments also demonstrated that the cryogel effectively eradicated microorganisms from wounds and accelerated the wound healing process. In addition, numerous studies have reported that catechol / iron coordination chelation has excellent photothermal antibacterial and adhesive properties for accelerating wound healing.

[0005] In summary, the present invention utilizes natural polysaccharide materials with excellent biocompatibility, biodegradability, inherent antibacterial properties, healing effects, low cost and easy chemical modification, and designs a series of hydrogel networks with different degrees of cross-linking by in situ cross-linking. Carboxymethyl chitosan not only has better water solubility than chitosan, but also retains amino groups that can form reversible dynamic cross-links with aldehyde groups. Secondly, sodium alginate can form corresponding aldehyde groups through oxidation with periodic acid, which can form injectable self-healing hydrogels in situ by shaking. It has shape adaptability and is suitable for wound repair of various shapes. Secondly, the excessive production of reactive oxygen species during wound repair triggers a long-term inflammatory response, delaying the healing rate of the wound. Therefore, the introduction of gallic acid, an antioxidant from a natural source, increases the functional properties of the hydrogel, namely enhanced mechanical properties, tissue adhesion and antioxidant activity. Finally, the metal coordination combination with iron ions also gives the hydrogel a powerful photothermal antibacterial effect. The properties of CMC / OSA / GA-Fe hydrogel described above will be comprehensively evaluated through physical and chemical experiments, cell and bacterial experiments, antioxidant experiments, and animal full-thickness wound models. Summary of the Invention

[0006] The present invention utilizes a hydrogel network formed by dynamic covalent crosslinking between carboxymethyl chitosan and oxidized sodium alginate (alginate aldehyde); further introduces gallic acid, a natural antioxidant with a catechol structure, to enhance the tightness of the hydrogel network and give the hydrogel certain adhesion and antioxidant properties; finally, the biomimetic mussel adhesive containing catechol and iron has strong tissue adhesion behavior under alkaline conditions and is suitable for dynamic wound treatment, thereby preparing a mussel-inspired multifunctional double-network crosslinked hydrogel wound dressing. In addition, catechol-Fe 3+ The metal coordination also exhibits a powerful antibacterial effect. Under near-infrared light irradiation, it can convert light energy into heat energy, which can be used to prevent and treat wound infections, shorten wound closure time, and prevent scar formation. The present invention has a simple preparation process and low cost, making it a medical material that promotes wound healing.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] Inspired by the adhesive behavior of marine mussels, and utilizing materials preparation techniques and methods, a multifunctional hydrogel adhesive was designed that combines injectability, self-healing properties, adhesion, hemostasis, photothermal antibacterial properties, antioxidant properties, and angiogenesis-promoting properties for accelerating the healing of full-thickness skin wounds. A dynamic covalently cross-linked hydrogel network was formed between carboxymethyl chitosan and oxidized sodium alginate. Gallic acid, a natural antioxidant with a catechol structure, was further introduced to enhance the tightness of the hydrogel network and impart certain adhesive and antioxidant properties to the hydrogel. Finally, the biomimetic mussel adhesive containing catechol and iron exhibited strong tissue adhesion under alkaline conditions, making it suitable for dynamic wound treatment. This resulted in the preparation of a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing.

[0009] A method for preparing a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing: natural materials such as carboxymethyl chitosan, alginate aldehyde, and gallic acid are selected to prepare a physicochemical double-cross-linked hydrogel network through imine bonds, metal coordination bonds, and weak hydrogen bonds; different -NH2 / -CHO ratios are used to prepare hydrogels with different degrees of cross-linking, and the catechol structure serves as a bridge to connect iron ions and the polymer network, enhancing the mechanical properties of the hydrogel. A series of multifunctional hydrogel dressings are prepared by combining the excellent biological properties of natural materials with dynamically cross-linked hydrogel networks.

[0010] The specific steps include:

[0011] (1) Sodium alginate is dissolved in deionized water and an oxidant, sodium periodate, is added to generate alginate aldehyde (OSA).

[0012] (2) terminating the oxidation of the alginate-aldehyde solution obtained in step (1) with ethylene glycol;

[0013] (3) placing the alginate aldehyde solution obtained in step (2) in a cellulose dialysis bag and dialysis purification;

[0014] (4) freeze-drying the purified alginate aldehyde solution obtained in step (3);

[0015] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) and dissolve it in PBS buffer under constant temperature and magnetic stirring;

[0016] (6) Dissolve carboxymethyl chitosan in PBS buffer under constant temperature and magnetic stirring;

[0017] (7) Weigh gallic acid and place it in alkaline PBS buffer, stirring thoroughly until dissolved;

[0018] (8) Adding ferric chloride hexahydrate powder to the solution obtained in step (7) under magnetic stirring conditions, stirring thoroughly to mix the mixture evenly, thereby obtaining a mixed solution of gallic acid chelated iron ions;

[0019] (9) Vortexing the mixed solution obtained in step (8) and the alginate aldehyde solution obtained in step (5) to obtain a hydrogel precursor solution;

[0020] (10) The carboxymethyl chitosan solution obtained in step (6) and the hydrogel precursor solution obtained in step (9) are vortex-dispersed evenly, and allowed to stand to obtain a double-network cross-linked adhesive hydrogel dressing based on carboxymethyl chitosan / alginate aldehyde / gallic acid-iron.

[0021] Furthermore, in step (1), the concentration of the sodium alginate solution is 2 wt %, the dissolution temperature is 50° C., the molar ratio of sodium alginate to sodium periodate is 1:1, and the oxidation time in the dark is 6 h.

[0022] Furthermore, in step (2), the mass ratio of the added amount of ethylene glycol to the sodium alginate is 1.5:1, and the termination reaction time is 1 hour.

[0023] Furthermore, in step (3), the cutoff capacity of the cellulose dialysis bag is 3500Da, the dialysis purification time is 3 days, and the water is changed every 6 hours.

[0024] Furthermore, in step (4), the freeze dryer temperature is -80°C and the drying time is 72 hours.

[0025] Furthermore, the concentration of the alginate aldehyde solution prepared in step (5) is 10 wt %, and the pH value of the PBS buffer solution is 7.0-7.4.

[0026] Furthermore, in step (6), the mass-to-volume ratio of carboxymethyl chitosan and PBS buffer is 0.05 g:1 ml, the constant temperature is 55° C., and the magnetic stirring time is 2-4 h.

[0027] Furthermore, in step (7), the gallic acid solution prepared has a PBS buffer concentration of 0.2 mol / L, a pH value of 8.5, and a gallic acid solution concentration of 1 wt%.

[0028] Furthermore, in step (8), the molar ratio of ferric chloride hexahydrate to gallic acid is 1:6, 1:3 or 2:3.

[0029] Furthermore, in step (9), in the obtained hydrogel precursor solution, the volume ratio of the mixed solution of gallic acid chelated iron ions to the alginate aldehyde solution is 3:5.

[0030] Furthermore, in step (10), in the obtained physicochemical double cross-linked adhesive hydrogel, the volume ratio of gallic acid-iron solution to alginate aldehyde solution to carboxymethyl chitosan solution is 3:5:10, and the vortex time is about 15 seconds.

[0031] A mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared by the above method.

[0032] The significant advantages of the present invention are:

[0033] (1) The present invention is based on the adhesion behavior of marine organisms such as mussels and is a multifunctional hydrogel dressing suitable for dynamic wounds.

[0034] (2) The present invention uses green and renewable marine polysaccharides to form dynamic covalent bonds, and then combines them with natural antioxidants and metal coordination bonds of iron ions to prepare a physicochemical double-crosslinked injectable self-healing hydrogel adhesive that can be used to repair wounds of various shapes.

[0035] (3) The prepared hydrogel has good biocompatibility and in vivo degradability, which can avoid secondary damage caused by changing dressings.

[0036] (4) Bacterial infection at the wound site is the main reason why wounds are difficult to heal. Traditional antibiotic treatments can easily cause bacteria to develop drug resistance. The photothermal therapy used in the present invention has the advantages of spectral antibacterial properties, remote control, and the ability to avoid drug resistance.

[0037] (5) The present invention has low synthesis cost, simple method, outstanding effect, and can be produced in batches and on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a SEM image (400×) of the hydrogel wound dressing prepared in Example 1;

[0039] Figure 2 is a SEM image (400×) of the hydrogel wound dressing prepared in Example 2;

[0040] Figure 3 is a SEM image (400×) of a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 3;

[0041] Figure 4 is a SEM image (400×) of a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 4;

[0042] Figure 5 is a SEM image (400×) of a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 5;

[0043] Figure 6 The mechanical properties test of the hydrogel wound dressing prepared in Examples 1-5;

[0044] Figure 7 This is a compression cycle unloading experiment of the hydrogel wound dressing prepared in Examples 1-5;

[0045] Figure 8 The macroscopic deformation recovery ability of the mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 4;

[0046] Figure 9 , 10 points are the macroscopic and microscopic adhesion effects of different materials for the preparation of mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing in Example 4;

[0047] Figure 11 The hydrogel wound dressing prepared in Example 1-5 was detected by NIR (808 nm, 1 w / cm 2 ) Temperature response data under stimulation;

[0048] Figure 12 This is an infrared imaging picture of the temperature change of the mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 4 at different powers;

[0049] Figure 13 The real-time temperature change monitoring after cycling the NIR after preparing the mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing in Example 4;

[0050] Figure 14 The microscopic evaluation of the bactericidal effect of the mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing prepared in Example 4 on Escherichia coli and Staphylococcus aureus under NIR response;

[0051] Figure 15 The hydrogel wound dressings prepared in Examples 1-5 were tested for scavenging DPPH free radicals, ABTS free radicals, and hydroxyl free radicals. DETAILED DESCRIPTION

[0052] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods. However, the following examples are merely examples of the present invention and do not represent the scope of protection of the rights defined by the present invention. The scope of protection of the rights of the present invention shall be subject to the claims.

[0053] Example 1

[0054] The preparation method of carboxymethyl chitosan / alginate aldehyde adhesive hydrogel (CMC / OSA) comprises the following steps:

[0055] (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added as an oxidant at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h.

[0056] (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour;

[0057] (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours;

[0058] (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours;

[0059] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS buffer (pH = 7.0-7.4) under constant temperature and magnetic stirring to dissolve it to prepare a 10 wt% alginate aldehyde solution;

[0060] (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h.

[0061] (7) Vortex mix the alkaline (pH = 8.5) 0.2 mol / L PBS buffer and the alginate solution obtained in step (5) at a volume ratio of 3:5;

[0062] (8) The carboxymethyl chitosan solution obtained in step (6) and the mixed solution obtained in step (7) were vortex-dispersed, wherein the volume ratio of the alkaline PBS buffer solution to the alginate aldehyde solution to the carboxymethyl chitosan solution was 3:5:10. The mixture was vortexed for about 15 seconds and allowed to stand to obtain a carboxymethyl chitosan / alginate aldehyde adhesive hydrogel.

[0063] Example 2

[0064] The preparation method of gallic acid modified carboxymethyl chitosan / alginate aldehyde adhesive hydrogel (CMC / OSA / GA) comprises the following steps:

[0065] (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added as an oxidant at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h.

[0066] (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour;

[0067] (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours;

[0068] (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours;

[0069] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS solution (pH = 7.0-7.4) under constant temperature and magnetic stirring to dissolve it, and prepare a 10 wt% alginate aldehyde solution;

[0070] (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h.

[0071] (7) Weigh gallic acid and place it in alkaline (pH = 8.5) 0.2 mol / L PBS buffer and stir thoroughly until dissolved to prepare a 1 wt% gallic acid solution;

[0072] (8) Vortex-mix the solution obtained in step (7) and the alginate aldehyde solution obtained in step (5) at a volume ratio of 3:5;

[0073] (9) The carboxymethyl chitosan solution obtained in step (6) and the mixed solution obtained in step (8) were vortex-dispersed, wherein the mass ratio of gallic acid, alginate aldehyde and carboxymethyl chitosan was 0.17:2.78:2.78, and the mixture was vortexed for about 15 seconds and allowed to stand to obtain a gallic acid-modified carboxymethyl chitosan / alginate aldehyde adhesive hydrogel.

[0074] Example 3

[0075] A method for preparing a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing (CMC / OSA / GA-Fe2.5) comprises the following steps:

[0076] (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added as an oxidant at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h.

[0077] (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour;

[0078] (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours;

[0079] (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours;

[0080] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS solution (pH = 7.0-7.4) under constant temperature and magnetic stirring to dissolve it, and prepare a 10 wt% alginate aldehyde solution;

[0081] (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h.

[0082] (7) Weigh gallic acid and place it in alkaline (pH = 8.5) 0.2 mol / L PBS buffer, stir thoroughly until dissolved, and prepare a 1 wt% gallic acid solution;

[0083] (8) Under magnetic stirring conditions, add ferric chloride hexahydrate powder to the solution obtained in step (7), stir thoroughly to mix thoroughly, and obtain a mixture of gallic acid chelated iron ions, wherein the molar ratio of ferric chloride hexahydrate to gallic acid is 1:6;

[0084] (9) Vortex-mixing the mixed solution obtained in step (8) and the alginate aldehyde solution obtained in step (5) at a volume ratio of 3:5 to obtain a hydrogel precursor solution;

[0085] (10) The carboxymethyl chitosan solution obtained in step (6) and the hydrogel precursor solution obtained in step (9) were vortexed and dispersed uniformly, with the volume ratio of gallic acid-iron solution to alginate aldehyde solution to carboxymethyl chitosan solution being 3:5:10. The solution was vortexed for about 15 seconds and allowed to stand to obtain a double-network cross-linked adhesive hydrogel dressing based on carboxymethyl chitosan / alginate aldehyde / gallic acid-iron.

[0086] Example 4

[0087] A method for preparing a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing (CMC / OSA / GA-Fe5) comprises the following steps:

[0088] (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added as an oxidant at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h.

[0089] (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour;

[0090] (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours;

[0091] (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours;

[0092] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS solution (pH = 7.0-7.4) under constant temperature and magnetic stirring to dissolve it, and prepare a 10 wt% alginate aldehyde solution;

[0093] (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h.

[0094] (7) Weigh gallic acid and place it in alkaline (pH = 8.5) 0.2 mol / L PBS buffer and stir thoroughly until dissolved to prepare a 1 wt% gallic acid solution;

[0095] (8) Under magnetic stirring conditions, add ferric chloride hexahydrate powder to the solution obtained in step (7), stir thoroughly to mix thoroughly, and obtain a mixture of gallic acid chelated iron ions, wherein the molar ratio of ferric chloride hexahydrate to gallic acid is 1:3;

[0096] (9) Vortex-mixing the mixed solution obtained in step (8) and the alginate aldehyde solution obtained in step (5) at a volume ratio of 3:5 to obtain a hydrogel precursor solution;

[0097] (10) The carboxymethyl chitosan solution obtained in step (6) and the hydrogel precursor solution obtained in step (9) were vortexed and dispersed uniformly, with the volume ratio of gallic acid-iron solution to alginate aldehyde solution to carboxymethyl chitosan solution being 3:5:10. The solution was vortexed for about 15 seconds and allowed to stand to obtain a double-network cross-linked adhesive hydrogel dressing based on carboxymethyl chitosan / alginate aldehyde / gallic acid-iron.

[0098] Example 5

[0099] A preparation method of a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing (CMC / OSA / GA-Fe10) comprises the following steps:

[0100] (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added as an oxidant at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h.

[0101] (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour;

[0102] (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours;

[0103] (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours;

[0104] (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS solution (pH = 7.0-7.4) under constant temperature and magnetic stirring to dissolve it, and prepare a 10 wt% alginate aldehyde solution;

[0105] (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h.

[0106] (7) Weigh gallic acid and place it in alkaline (pH = 8.5) 0.2 mol / L PBS buffer, stir thoroughly until dissolved, and prepare a 1 wt% gallic acid solution;

[0107] (8) Under magnetic stirring conditions, add ferric chloride hexahydrate powder to the solution obtained in step (7), stir thoroughly to mix thoroughly, and obtain a mixture of gallic acid chelated iron ions, wherein the molar ratio of ferric chloride hexahydrate to gallic acid is 2:3;

[0108] (9) Vortex-mixing the mixed solution obtained in step (8) and the alginate aldehyde solution obtained in step (5) at a volume ratio of 3:5 to obtain a hydrogel precursor solution;

[0109] (10) The carboxymethyl chitosan solution obtained in step (6) and the hydrogel precursor solution obtained in step (9) were vortexed and dispersed uniformly, with the volume ratio of gallic acid-iron solution to alginate aldehyde solution to carboxymethyl chitosan solution being 3:5:10. The solution was vortexed for about 15 seconds and allowed to stand to obtain a double-network cross-linked adhesive hydrogel dressing based on carboxymethyl chitosan / alginate aldehyde / gallic acid-iron.

[0110] The SEM images of the hydrogel (CMC / OSA) wound dressing prepared in Example 1 are shown in FIG. Figure 1 .

[0111] The SEM images of the hydrogel (CMC / OSA / GA) wound dressing prepared in Example 2 are shown in FIG. Figure 2 .

[0112] The SEM images of the mussel-inspired multifunctional double-network cross-linked hydrogel (CMC / OSA / GA-Fe2.5) wound dressing prepared in Example 3 are shown in FIG. Figure 3 .

[0113] The SEM images of the mussel-inspired multifunctional double-network cross-linked hydrogel (CMC / OSA / GA-Fe5) wound dressing prepared in Example 4 are shown in FIG. Figure 4 .

[0114] The SEM images of the mussel-inspired multifunctional double-network cross-linked hydrogel (CMC / OSA / GA-Fe10) wound dressing prepared in Example 5 are shown in FIG. Figure 5 .

[0115] Microscopic observation of the prepared hydrogels revealed that as the concentration of the gallic acid-iron precursor solution increased, the hydrogels in Examples 3, 4, and 5 exhibited a denser network structure. In particular, the gel prepared in Example 4 exhibited a more uniform network, without the network collapse that can occur with overly rapid cross-linking. Calculated porosity of the hydrogels exceeded 70%, facilitating wound fluid exudation and gas exchange.

[0116] Mechanical properties testing of mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing:

[0117] The hydrogel was prepared into a cylindrical sample with a diameter of 10 mm and a height of 10 mm. The hydrogel material was subjected to compression test in the axial direction using a universal testing machine. The compression rate during the test was 5 mm / min. The maximum compression strength that the hydrogel could withstand was measured. The results are shown in Figure 6 Through compression testing, all groups of hydrogels showed good mechanical strength. The hydrogel group of Example 4 had the best mechanical strength. This was because the incorporation of gallic acid and iron ions increased the tightness of the internal network of the hydrogel. In addition, each group of hydrogels was subjected to a 50% deformation compression cycle. The results were as follows: Figure 7 (From left to right: CMC / OSA, CMC / OSA / GA, CMC / OSA / GA-Fe2.5, CMC / OSA / GA-Fe5, CMC / OSA / GA-Fe10). Through deformation recovery ability, we can find that compared with the CMC / OSA hydrogel group composed only of simple imine bonds, the CMC / OSA / GA and CMC / OSA / GA-Fe hydrogels have good energy dissipation effects due to the presence of multiple hydrogen bonds and metal coordination bonds. This shows that the hydrogels in Example 4 have both rigid networks and flexible structures, and can well adapt to the recovery ability of wounds after multiple deformations caused by exercise. The results are shown in Figure 2. Figure 8 .

[0118] Adhesion ability of mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing:

[0119] Example 4 Macroscopic effect of hydrogel adhesion to different materials such as metal, plastic, glass, skin and rat viscera. Figure 9 Subsequently, the microstructure of the hydrogel adhesion sample interface was observed using a scanning electron microscope. Figure 10Hydrogels have a certain adhesion effect on various types of materials. This is because the polymerized aldehyde groups, quinone groups and phenolic hydroxyl groups in the hydrogels can form corresponding physical and chemical bonds with the surface of the material, so that the hydrogel dressing can adhere well to the wound surface without falling off.

[0120] Photothermal capability and antibacterial effect of mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing:

[0121] The photothermal conversion performance of the hydrogel was evaluated by NIR irradiation. The same volume of hydrogel was placed in a 5 ml EP tube and irradiated with 1 w / cm 2 The 808 nm laser was irradiated continuously for 10 min, and the temperature change was recorded in real time using a thermal infrared imager (UTi160D, China). Figure 11 As shown. The hydrogel has a good ability to convert light energy into temperature through the metal coordination bond between catechol and iron ions. In addition, by increasing the power density of NIR from 1w / cm 2 Change to 2.5 w / cm 2 The photothermal tunability of the hydrogel in Example 4 was studied. Figure 12 The temperature change of the photothermal imager shows that the hydrogel of Example 4 has a good thermal response ability to light sources of different intensities. The photothermal stability of the hydrogel of Example 4 was tested by measuring the temperature change of the hydrogel under three on / off irradiation cycles. The results are shown in Figure 13 In addition, we determined the interaction between the hydrogel of Example 4 and Gram-positive bacteria ( S.aures ) and Gram-negative bacteria ( E. coli ) were cultured together, and the bacterial survival after NIR treatment was observed. The corresponding bacterial micromorphology was observed by scanning electron microscopy. The results are as follows Figure 14 As shown in the figure, heating can destroy the cell membrane structure of bacteria and thus play a good bactericidal role.

[0122] Free radical scavenging ability of mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing:

[0123] Excessive free radicals at the wound site usually lead to strong oxidative stress, causing enzyme inactivation, lipid peroxidation and DNA damage in normal cells, thereby delaying wound healing. Therefore, wound dressings with free radical scavenging properties are beneficial to wound healing. The antioxidant capacity of hydrogel dressings was evaluated by simulating free radical generation in vitro and then changing the corresponding free radical content after material treatment. Figure 15 As shown, we found that it has a good scavenging effect on both nitrogen free radicals (DPPH or ABTS) and hydroxyl free radicals, especially the hydrogel group containing plant polyphenol gallic acid can achieve a scavenging rate of more than 80%, which can accelerate the transition from the inflammatory phase to the proliferative phase at the wound and thus accelerate the wound healing time.

[0124] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a mussel-inspired multifunctional double-network cross-linked hydrogel wound dressing, characterized by: The following steps are involved: (1) Sodium alginate was dissolved in deionized water, and sodium periodate was added at a molar ratio of 1:1 to generate alginate aldehyde (OSA), which was then oxidized in the dark for 6 h. (2) The alginate aldehyde solution obtained in step (1) was oxidized by terminating the oxidation with ethylene glycol, wherein the mass ratio of ethylene glycol to sodium alginate was 1.5:1, and the oxidation was terminated for 1 hour; (3) The alginate aldehyde solution obtained in step (2) was placed in a cellulose dialysis bag with a cutoff of 3500 Da, and dialyzed for purification for 3 days, with the water being changed every 6 hours; (4) The purified alginate aldehyde solution obtained in step (3) was placed in a freeze dryer at -80°C and freeze-dried for 72 hours; (5) Weigh the freeze-dried alginate aldehyde powder obtained in step (4) into a beaker, add PBS solution with pH = 7.0-7.4 under constant temperature and magnetic stirring to dissolve it, and prepare a 10 wt% alginate aldehyde solution; (6) Dissolve carboxymethyl chitosan in PBS buffer at a mass to volume ratio of 0.05 g:1 ml under constant temperature magnetic stirring conditions and stir at 55°C for 2-4 h. (7) Weigh gallic acid and place it in 0.2 mol / L PBS buffer at pH 8.

5. Stir thoroughly until dissolved to prepare a 1 wt% gallic acid solution. (8) Under magnetic stirring conditions, add ferric chloride hexahydrate powder to the solution obtained in step (7), stir thoroughly to mix thoroughly, and obtain a mixture of gallic acid chelated iron ions, wherein the molar ratio of ferric chloride hexahydrate to gallic acid is 1:3; (9) Vortex-mixing the mixed solution obtained in step (8) and the alginate aldehyde solution obtained in step (5) at a volume ratio of 3:5 to obtain a hydrogel precursor solution; (10) The carboxymethyl chitosan solution obtained in step (6) and the hydrogel precursor solution obtained in step (9) were vortexed and dispersed uniformly. The volume ratio of the mixed solution of gallic acid chelated iron ions, 10 wt% alginate aldehyde solution and carboxymethyl chitosan solution was 3:5:

10. The mixture was vortexed for 15 seconds and allowed to stand to obtain a double-network cross-linked adhesive hydrogel dressing based on carboxymethyl chitosan / alginate aldehyde / gallic acid-iron.

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