Double-network hydrogel based on sodium alginate / gelatin, preparation method and dressing

Abstract

The invention belongs to the field of high polymer material chemistry, and particularly relates to double-network hydrogel based on sodium alginate / gelatin, a preparation method and dressing. A chemical method of grafting modification is adopted, grafting modification is carried out by designing abundant active groups on side chains of gelatin and sodium alginate, and based on traditional gelatin or sodium alginate hydrogel, not only is the thermal stability of gelatin improved, but also the biological activity of sodium alginate is improved, and the antibacterial property is achieved; the finally prepared SD / GelMA dual-network hydrogel wound dressing not only has excellent mechanical properties, but also has very high biocompatibility and antibacterial activity, and has huge application prospects and potential in the aspect of skin wound healing.

Description

Technical Field

[0001] The present invention belongs to the field of polymer material chemistry, and specifically relates to a double-network hydrogel based on sodium alginate / gelatin, a preparation method thereof, and a dressing. Background Art

[0002] The skin is an important tissue and organ covering the body surface and in direct contact with the external environment. It has the functions of sensing external stimuli, regulating body temperature, and protecting the body from external damage. Since it is in direct contact with the outside world, the skin has become one of the most vulnerable tissues. The main function of a wound dressing is to cover the wound, form a defense line to resist the invasion of external bacteria, and promote the rearrangement and fusion of skin cells, thereby playing a positive role in wound recovery.

[0003] Hydrogels are composed of a three-dimensional cross-linked hydrophilic polymer network and can retain a large amount of water. Due to their high water content and modulus similar to that of human skin, they can simulate the mechanical energy and chemical environment of biological tissues and show great application prospects in the field of wound dressings. At the same time, the graft modification material preparation technology is a material modification technology with simple operation, good modification effect, and wide application range. Grafted modified materials have been widely used in many fields due to their good mechanical properties and high thermal stability. The gel wound dressing prepared from grafted modified materials combines the advantages of hydrogels and has the characteristics of grafted modified materials, showing great prospects and potential in skin wound healing and becoming a research hotspot recently.

[0004] Chinese Patent CN201610915228.2 discloses a preparation method of a controllable-release antibiotic hydrogel composite material. This new composite material not only solves the problem of unreasonable antibiotic release rate but also endows the hydrogel with high-efficiency and broad-spectrum antibacterial properties, preparing a hydrogel dressing with good biocompatibility and high antibiotic utilization rate. However, at present, the research on antibiotic hydrogel dressings is relatively less, the preparation process is complex, and the antibiotic hydrogel dressings are prone to drug resistance problems, severely limiting their application.

[0005] Chinese Patent CN202110652606.3 discloses a preparation method of a hydrogel dressing containing a metal sulfide doped with foreign ions. This hydrogel dressing not only exhibits continuous activity but also has the potential to replace antibiotics in reducing drug abuse and the development of drug resistance. However, at present, the price of metal ion hydrogel dressings is high, and metal ion hydrogel dressings are toxic to normal cells, severely limiting their application.

[0006] Therefore, providing a hydrogel wound dressing with simple preparation, significantly improved mechanical properties, and high biocompatibility with biological tissues is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention discloses a double-network hydrogel based on sodium alginate / gelatin, a preparation method and a dressing. Gelatin and sodium alginate monomers with excellent biocompatibility are selected, and graft modification is carried out through the design of rich active groups on the side chains to synthesize a hydrogel dressing with an interpenetrating network, combining the advantages of natural polymers and synthetic polymers, retaining both the high mechanical properties of synthetic polymers and having good biocompatibility and excellent antibacterial properties.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The first technical object of the present invention is to provide a double-network hydrogel based on sodium alginate / gelatin. The hydrogel has a porous structure with a pore diameter of 10 - 20 μm. The porous structure endows it with a high specific surface area and good permeability, which is conducive to cell attachment and proliferation, and also helps the transport of nutrients and metabolic wastes. In addition, the moist environment of the hydrogel is also beneficial to wound repair and reduces the formation of wound scars; and in the hydrogel, the mass concentration of gelatin is 10wt% - 20wt%, and the mass concentration of sodium alginate is 1wt% - 2wt%.

[0010] The second technical object of the present invention is to provide a preparation method of the double-network hydrogel based on sodium alginate / gelatin as described above, including the following steps:

[0011] (1) Synthesize methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer;

[0012] (2) Synthesize dopamine hydrochloride (DA)-modified sodium alginate (SD) monomer;

[0013] (3) Carry out ultraviolet polymerization and ionic cross-linking on the graft-modified GelMA and SD monomers to prepare a wound dressing based on the SD / GelMA double-network hydrogel.

[0014] Further, in step (1), the specific operation of synthesizing methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer is as follows:

[0015] 1) Dissolve gelatin in PBS buffer solution (pH = 7.5) at 50 °C, stir (stirring rate: 500 - 800 rpm) for 2 h to obtain a gelatin aqueous solution;

[0016] 2) Add the methacryloyl anhydride (MA) solution to the gelatin aqueous solution prepared in step 1), and continue to stir at 500 - 800 rpm at room temperature for 3 h, and set aside;

[0017] 3) Add distilled water to the solution prepared in step 2) to quench the reaction to obtain a crude product;

[0018] 4) Purify the crude product using a dialysis bag (3500D) and dialyze it at 40 °C for 7 days, changing the water regularly, 3 times a day.

[0019] 5) Place the solution after dialysis in step 4) into a freeze dryer and freeze-dry it at -60 °C to obtain the methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer.

[0020] Furthermore, the mass ratio of gelatin to PBS buffer solution is 1:9, and the mass ratio of gelatin aqueous solution to MA solution is 20:1.

[0021] It should be noted that in the technical solution of the present invention, the mass ratio of gelatin to PBS buffer solution is 1:9, and the mass ratio of gelatin aqueous solution to MA solution is 20:1. The methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer synthesized thereby has a high yield, good concentration, and good thermal stability, and is suitable for subsequent applications.

[0022] Moreover, the reaction in step 1) is carried out at 50 °C to improve the experimental efficiency and accelerate dissolution; the reaction in step 2) is carried out at room temperature to prevent the decomposition of methacryloyl anhydride (MA) by heat and ensure the experimental efficiency and effect; in step 1), stir at 500 - 800 rpm for 2 h at 50 °C to make the reaction more complete and increase its yield; in step 2), stir at 500 - 800 rpm for 3 h at room temperature to make the reaction more complete and increase its yield; in step 5), purify using a dialysis bag (3500D), dialyze at 40 °C for 7 days, change the water regularly, 3 times a day, to further wash and purify the crude product, and the concentration of the methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer prepared thereby is higher; in step 6), freeze-dry the solution at -60 °C to remove water, which is beneficial for preservation.

[0023] Further, in step (2), the specific operation for synthesizing the dopamine hydrochloride (DA)-modified sodium alginate (SD) monomer is as follows:

[0024] 1) Dissolve sodium alginate in pure water at 25 °C and stir (stirring rate: 500 - 800 rpm) for 12 h to obtain a sodium alginate aqueous solution.

[0025] 2) Add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the sodium alginate aqueous solution, then adjust the pH to 5 - 6, and continue to stir at 500 - 800 rpm at room temperature for 1 h for standby.

[0026] 3) Add dopamine hydrochloride (DA) to the solution prepared in step 2), and stir at room temperature (stirring rate: 500 - 800 rpm) for 24 h to obtain a crude product;

[0027] 4) Purify the crude product with a dialysis bag (3500D) and dialyze at room temperature for 3 days;

[0028] 5) Put the solution completed in step 4) into a freeze dryer and freeze-dry at -60 °C to finally obtain the dopamine (DA)-modified sodium alginate (SD) monomer.

[0029] Furthermore, the mass ratio of sodium alginate to pure water is 1:49, and the molar ratio of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) to dopamine hydrochloride (DA) is 1:1:1.

[0030] It should be noted that in the technical solution of the present invention, the mass ratio of sodium alginate to water is 1:49, and the molar ratio of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) to dopamine hydrochloride (DA) is 1:1:1, which is the optimal molar ratio for the experiment. The dopamine (DA)-modified sodium alginate (SD) monomer synthesized therefrom has a high yield, good concentration and excellent performance, and is suitable for subsequent applications.

[0031] Moreover, the reaction in step 1) is carried out at 25 °C to improve the experimental efficiency and accelerate dissolution; the reactions in steps 2), 3) and 4) are carried out at room temperature, which is easy to operate and control; in step 3), stirring at 500 - 800 rpm at room temperature for 24 h makes the reaction more complete and increases its yield; in step 2), the pH is adjusted to 5 - 6 to promote the chemical reaction between sodium alginate and dopamine and form a stable structure to ensure the effect of the reaction; in step 4), purification with a dialysis bag (3500D) and dialysis at room temperature for 3 days results in a higher concentration of the dopamine (DA)-modified sodium alginate (SD) monomer; in step 5), the solution is freeze-dried at -60 °C to remove moisture, which is beneficial for storage.

[0032] Further, in step (3), the specific operation for preparing the SD / GelMA double-network hydrogel dressing is as follows:

[0033] 1) Dissolve the synthesized methacrylated gelatin GelMA monomer and I-184 photoinitiator in pure water and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0034] 2) Add the synthesized sodium alginate SD monomer modified by dopamine hydrochloride (DA) to the solution in step 1), and continue to stir and dissolve it at 50 °C at 500 - 800 rpm for 1 h until the solution is completely dissolved;

[0035] 3) Remove the microbubbles from the solution in step 2) by ultrasound (ultrasonic power is 100%) to obtain a prepolymer solution;

[0036] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4 × 4 × 0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0037] 5) Transfer the mold in step 4) to an ultraviolet lamp with a wavelength of 365 nm and irradiate it for 1 h. Through the photopolymerization reaction, form the first network gel of hydrogen bond cross-linking of GelMA polymerization;

[0038] 6) Immerse the gel in step 5) in a CaCl2 solution for ionic cross-linking at room temperature for 30 min to form the second network of ionic cross-linking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from the graft-modified material, which is named SD-GelMA hydrogel wound dressing, that is, the hydrogel wound dressing based on sodium alginate / gelatin described above.

[0039] Furthermore, the mass ratio of GelMA monomer, I-184 photoinitiator, and SD monomer is 10 - 20:1:1 - 4.

[0040] It should be noted that in the technical solution of the present invention, the mass concentration of GelMA for preparing SD-GelMA hydrogel is 10 wt% - 20 wt%, and the mass concentration of SD is 1 wt% - 2 wt%. The prepared hydrogel has good mechanical properties and excellent biocompatibility, providing a solution to the shortcomings of weak mechanical properties and poor biocompatibility of current hydrogel dressings.

[0041] Moreover, the solution in step 3) removes the microbubbles by ultrasound (ultrasonic power is 100%) to ensure the stability and mechanical properties of the hydrogel; in step 5), an ultraviolet lamp with a wavelength of 365 nm is selected, and the energy of ultraviolet is used to accelerate the formation of the gel network. The polymerization time is 1 h, so that the chains of the hydrogel network are in full contact, and the complete network is more stable and has stronger mechanical properties.

[0042] The third technical object of the present invention is to provide an application of the double-network hydrogel based on sodium alginate / gelatin prepared by the above method in the medical field.

[0043] Furthermore, the double-network hydrogel based on sodium alginate / gelatin is a medical-grade hydrogel and can be used as a medical dressing.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] The present invention provides a graft modification chemical method. By designing the side chain group structures of gelatin and sodium alginate, graft modification is carried out, which not only improves the thermal stability of gelatin, but also improves the biological activity of sodium alginate and endows it with antibacterial properties. Finally, the prepared SD / GelMA double-network hydrogel wound dressing not only has excellent mechanical properties, but also has high biocompatibility and antibacterial properties, and has great prospects and potential in skin wound healing. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0047] Figure 1 It is the preparation diagram of the modified gelatin (GelMA) monomer in the present invention;

[0048] Figure 2 It is the preparation diagram of the modified sodium alginate (SD) monomer in the present invention;

[0049] Figure 3 It is the synthesis schematic diagram of the SD / GelMA double-network hydrogel wound dressing in the present invention;

[0050] Figure 4 It is the nuclear magnetic resonance hydrogen spectrum analysis of the SD / GelMA double-network hydrogel wound dressing in the present invention;

[0051] Figure 5 It is the infrared characterization diagram of SD and GelMA prepared in Example 3;

[0052] Figure 6 It is the mechanical property comparison diagram of the hydrogels prepared in Examples 1-6, Comparative Example 1, Comparative Example 2 and Example 3;

[0053] Figure 7 It is the antibacterial experiment diagram of the SD / GelMA double-network hydrogel wound dressing prepared in Example 3;

[0054] Figure 8 It is the cytotoxicity experiment diagram of the SD / GelMA double-network hydrogel wound dressing prepared in Example 3;

[0055] Figure 9 It is the wound healing experiment diagram of the SD / GelMA double-network hydrogel wound dressing prepared in Example 3 for mouse wounds. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Here, the special term "embodiment", any embodiment described as "exemplary" does not have to be construed as superior to or better than other embodiments. For the performance index tests in the embodiments of the present application, unless otherwise specified, the conventional test methods in the art are adopted. It should be understood that the terms described in the present application are only for describing specific embodiments and are not used to limit the content disclosed in the present application.

[0058] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present application belongs; other test methods and technical means not specifically noted in the present application refer to the experimental methods and technical means commonly adopted by those of ordinary skill in the art.

[0059] To better illustrate the content of the present application, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present application can be implemented without some specific details. In the embodiments, some methods, means, instruments, devices, etc. well-known to those skilled in the art are not described in detail to highlight the gist of the present application.

[0060] On the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the obtained technical solutions belong to the content disclosed in the embodiments of the present application.

[0061] The present invention discloses a double-network hydrogel based on sodium alginate / gelatin, a preparation method and a dressing.

[0062] To better understand the present invention, the following embodiments are used to further specifically illustrate the present invention, but it should not be understood as a limitation of the present invention. For some non-essential improvements and adjustments made by those skilled in the art according to the above-mentioned invention content, they are also considered to fall within the protection scope of the present invention.

[0063] Example 1:

[0064] A preparation method of a hydrogel wound dressing prepared from a graft-modified material, comprising the following steps:

[0065] (1) Synthesize gelatin (GelMA) monomers modified with methacrylic anhydride (MA)

[0066] 1) Dissolve gelatin (10 g, 0.2 mmol) in PBS buffer solution (pH = 7.5) at 50 °C, stir (stirring rate: 500 - 800 rpm) for 2 h to obtain a 10% gelatin aqueous solution;

[0067] 2) Add analytical pure MA (0.5 g, 3.24 mmol) to the solution in step 1). The mass ratio of MA to the solution in step 1) is 1:20, and continue to stir at 500 - 800 rpm at room temperature for 3 h;

[0068] 3) Add distilled water to the solution in step 2) to quench the reaction and obtain a crude product;

[0069] 4) Purify the crude product with a dialysis bag (3500D), collect the product and dialyze it at 40 °C for 7 days, changing water regularly, 3 times a day;

[0070] 5) Put the solution after dialysis in step 4) into a freeze dryer and freeze-dry it at -60 °C to obtain a methacryloyl anhydride (MA)-modified gelatin (GelMA) monomer.

[0071] (2) Synthesize dopamine hydrochloride (DA)-modified sodium alginate (SD) monomer:

[0072] 1) Dissolve sodium alginate with a purity of 98% (0.5 g, 2.31 mmol) in pure water at 25 °C, stir (stirring rate: 500 - 800 rpm) for 12 h to obtain a 2% sodium alginate aqueous solution;

[0073] 2) Add 5 mmol of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) with a purity of 98% and 5 mmol of N-hydroxysuccinimide (NHS) with a purity of 98% to the solution in step 1), then adjust the pH to 5 - 6, and continue to stir at 500 - 800 rpm at room temperature for 1 h;

[0074] 3) Add 5 mmol of dopamine hydrochloride (DA) with a purity of 98% to the solution in step 2), stir (stirring rate: 500 - 800 rpm) at room temperature for 24 h to obtain a crude product;

[0075] 4) Purify the crude product with a dialysis bag (3500D) and dialyze it at room temperature for 3 days;

[0076] 5) Put the solution after dialysis in step 4) into a freeze dryer and freeze-dry it at -60 °C to obtain the SD monomer.

[0077] Example 2:

[0078] Preparation of 10wt% GelMA and 1wt% SD SD / GelMA double-network hydrogel wound dressing:

[0079] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.05 g, 0.02 mmol) in 4.4 g of pure water, and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0080] 2) Add SD (0.05 g, 0.23 mmol) to the solution in step 1), and continue to stir and dissolve at 500 - 800 rpm at 50 °C for 1 h until the solution is completely dissolved;

[0081] 3) Remove the microbubbles from the solution in step 2) by ultrasound (ultrasound power is 100%) to obtain a prepolymer solution;

[0082] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4×4×0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0083] 5) Transfer the mold in step 4) to a UV lamp with a wavelength of 365 nm and irradiate for 1 h. Through a photoinitiated polymerization reaction, form a hydrogen bond-crosslinked first network gel of GelMA polymerization;

[0084] 6) Place the gel in step 5) in a saturated CaCl2 solution with a purity of 98% and perform ionic crosslinking at room temperature for 30 min to form a second network of ionic crosslinking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from a graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0085] In this example, the concentration of GelMA is 10wt% of the total mass of the prepolymer solution, and the concentration of SD is 1wt% of the total mass of the prepolymer solution. Through tensile testing, the mechanical properties of the hydrogel wound dressing are tested. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 32.75 KPa, and the tensile strain is 91.85 times.

[0086] Example 3:

[0087] Preparation of 10wt% GelMA and 2wt% SD SD / GelMA double-network hydrogel wound dressing:

[0088] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.025 g, 0.02 mmol) in 4.375 g of pure water, and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0089] 2) Add SD (0.10 g, 0.46 mmol) to the solution obtained in step 1), and continue to stir and dissolve at 50 °C at 500 - 800 rpm for 1 h until the solution is completely dissolved;

[0090] 3) Remove the minute bubbles from the solution in step 2) by ultrasonic treatment (ultrasonic power: 100%) to obtain a prepolymer solution;

[0091] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4×4×0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0092] 5) Transfer the mold in step 4) to an ultraviolet lamp with a wavelength of 365 nm and irradiate for 1 h. Through the photoinitiated polymerization reaction, a hydrogen bond-crosslinked first network gel of GelMA polymerization is formed;

[0093] 6) Place the gel in step 5) in a saturated CaCl₂ solution with a purity of 98% for ionic crosslinking at room temperature for 30 min to form a second network of ionic crosslinking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from the graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0094] In this example, the concentration of GelMA is 10 wt% of the total mass of the prepolymer solution, and the concentration of SD is 2 wt% of the total mass of the prepolymer solution. Through tensile testing, the mechanical properties of the hydrogel wound dressing are tested. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 75.12 KPa, and the tensile strain is 116.87 times.

[0095] Example 4:

[0096] Prepare an SD / GelMA double-network hydrogel wound dressing with 10 wt% GelMA and 3 wt% SD:

[0097] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.05 g, 0.02 mmol) in 4.3 g of pure water, and stir (stirring rate: 500 - 800 rpm) and dissolve at 50 °C for 45 min;

[0098] 2) Add SD (0.15 g, 0.69 mmol) to the solution in step 1), and continue to stir and dissolve at 50 °C at 500 - 800 rpm for 1 h until the solution is completely dissolved;

[0099] 3) Remove the minute bubbles from the solution in step 2) by ultrasonic treatment (ultrasonic power: 100%) to obtain a prepolymer solution;

[0100] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4×4×0.1 cm in length, width, and height through an injector, and naturally cool it to room temperature;

[0101] 5) Transfer the mold from step 4) to a UV lamp with a wavelength of 365 nm and irradiate it for 1 h. Through the polymerization reaction initiated by light, a hydrogen bond-crosslinked first network gel of GelMA polymerization is formed;

[0102] 6) Place the gel from step 5) in a saturated CaCl2 solution with a purity of 98% and perform ionic crosslinking at room temperature for 30 min to form a second network of ionic crosslinking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from a graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0103] In this example, the concentration of GelMA is 10 wt% of the total mass of the prepolymer solution, and the concentration of SD is 3 wt% of the total mass of the prepolymer solution. Through tensile testing, the mechanical properties of the hydrogel wound dressing are tested. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 121.70 KPa, and the tensile strain is 114.84 times.

[0104] From the above Examples 2 - 4, it can be seen that the strain first increases and then decreases. This is because when the concentration of SD increases, the number of polymer chains in the solution increases, and the number of ionic crosslinking points formed with Ca 2+ increases, which can more effectively disperse and transfer the externally applied force, thus improving the stress of the hydrogel. However, it will also increase the rigidity of the gel, resulting in a decrease in the overall ductility of the hydrogel. The SD concentration of 2 wt% is selected as the ratio for subsequent experiments.

[0105] Example 5:

[0106] Prepare an SD / GelMA double-network hydrogel dressing with 15 wt% GelMA and 2 wt% SD:

[0107] 1) Dissolve GelMA (0.75 g, 0.015 mmol) and I-184 photoinitiator (0.075 g, 0.03 mmol) in 4.075 g of pure water, and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0108] 2) Add SD (0.10 g, 0.46 mmol) to the solution from step 1), and continue to stir and dissolve at 500 - 800 rpm at 50 °C for 1 h until the solution is completely dissolved;

[0109] 3) Remove the minute bubbles from the solution in step 2) by ultrasonic (ultrasonic power is 100%) to obtain the prepolymer solution;

[0110] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4×4×0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0111] 5) Transfer the mold from step 4) to a UV lamp with a wavelength of 365 nm and irradiate it for 1 h. Through the photo-induced polymerization reaction, a hydrogen-bond cross-linked first network gel of GelMA polymerization is formed;

[0112] 6) Place the gel from step 5) in a saturated CaCl2 solution with a purity of 98% and perform ionic cross-linking at room temperature for 30 min to form a second network of ionic cross-linking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from a graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0113] In this example, the concentration of GelMA is 15 wt% of the total mass of the prepolymer solution, and the concentration of SD is 2 wt% of the total mass of the prepolymer solution. Through tensile testing, the mechanical properties of the hydrogel wound dressing are tested. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 89.84 KPa, and the tensile strain is 75.10 times.

[0114] Example 6:

[0115] Prepare an SD / GelMA double-network hydrogel dressing with 20 wt% GelMA and 2 wt% SD:

[0116] 1) Dissolve GelMA (1 g, 0.02 mmol) and I-184 photoinitiator (0.1 g, 0.04 mmol) in 3.8 g of pure water, and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0117] 2) Add SD (0.10 g, 0.46 mmol) to the solution from step 1), and continue to stir and dissolve at 50 °C at 500 - 800 rpm for 1 h until the solution is completely dissolved;

[0118] 3) Remove the minute bubbles from the solution in step 2) by ultrasonic (ultrasonic power is 100%) to obtain the prepolymer solution;

[0119] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4×4×0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0120] 5) Transfer the mold from step 4) to a UV lamp with a wavelength of 365 nm and irradiate it for 1 h. Through the photo-induced polymerization reaction, a hydrogen-bond cross-linked first network gel of GelMA polymerization is formed;

[0121] 6) Place the gel from step 5) in a saturated CaCl2 solution with a purity of 98% and perform ionic crosslinking at room temperature for 30 min to form a second network of ionic crosslinking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from the graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0122] In this example, the concentration of GelMA is 20 wt% of the total mass of the prepolymer solution, and the concentration of SD is 2 wt% of the total mass of the prepolymer solution. The mechanical properties of the hydrogel wound dressing are tested by tensile testing. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 76.12 KPa, and the tensile strain is 53.45 times.

[0123] In summary of Examples 5 and 6, as the concentration of GelMA monomer increases, the strain decreases and the stress increases. This is because the increase in the concentration of GelMA monomer leads to an increase in crosslinking density, an increase in the rigidity of the network structure, a change in intermolecular forces, and a restriction of polymer chain movement. The combined effect of these factors results in an increase in stress and a decrease in strain of the hydrogel.

[0124] In summary of the results of the above examples, Example 3 with a GelMA concentration of 10 wt% and an SD concentration of 2 wt% is selected as the subsequent ratio for the experiment.

[0125] Example 7:

[0126] Prepare an SD / GelMA double-network hydrogel dressing crosslinked at a wavelength of 289 nm with 10 wt% GelMA and 2 wt% SD:

[0127] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.05 g, 0.02 mmol) in 4.35 g of pure water and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve.

[0128] 2) Add SD (0.10 g, 0.46 mmol) to the solution from step 1) and continue to stir and dissolve at 50 °C at 500 - 800 rpm for 1 h until the solution is completely dissolved.

[0129] 3) Remove the microbubbles from the solution in step 2) by ultrasound (ultrasound power is 100%) to obtain a prepolymer solution.

[0130] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4 × 4 × 0.1 cm in length, width, and height through an injector and let it cool naturally to room temperature.

[0131] 5) Transfer the mold in step 4) to be irradiated under an ultraviolet lamp with a wavelength of 280 nm for 1 h. Through the photo-initiated polymerization reaction, a hydrogen-bond cross-linked first network gel of GelMA polymerization is formed;

[0132] 6) Place the gel in step 5) in a saturated CaCl2 solution with a purity of 98% for ionic cross-linking at room temperature for 30 min to form a second network of ionic cross-linking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from the graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0133] In this example, the concentration of GelMA is 10 wt% of the total mass of the prepolymer solution, the concentration of SD is 2 wt% of the total mass of the prepolymer solution, the ultraviolet wavelength for cross-linking is 280 nm, and the mechanical properties of the hydrogel wound dressing are tested through a tensile test. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 118.21 KPa, and the tensile strain is 49.45 times.

[0134] Example 8:

[0135] Prepare an SD / GelMA double-network hydrogel dressing with 10 wt% GelMA and 2 wt% SD cross-linked at a wavelength of 420 nm:

[0136] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.05 g, 0.02 mmol) in 4.35 g of pure water and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0137] 2) Add SD (0.10 g, 0.46 mmol) to the solution in step 1) and continue to stir and dissolve at 500 - 800 rpm at 50 °C for 1 h until the solution is completely dissolved;

[0138] 3) Remove the minute bubbles from the solution in step 2) by ultrasound (ultrasound power is 100%) to obtain a prepolymer solution;

[0139] 4) Inject the prepolymer solution into a self-made glass mold with dimensions of 4 × 4 × 0.1 cm in length, width, and height through an injector and let it cool naturally to room temperature;

[0140] 5) Transfer the mold in step 4) to be irradiated under an ultraviolet lamp with a wavelength of 420 nm for 1 h. Through the photo-initiated polymerization reaction, a hydrogen-bond cross-linked first network gel of GelMA polymerization is formed;

[0141] 6) Place the gel in step 5) in a saturated CaCl2 solution with a purity of 98% and perform ionic crosslinking at room temperature for 30 min to form a second network of ionic crosslinking between sodium alginate and calcium ions, so as to finally obtain a hydrogel dressing prepared from the graft-modified material, which is named SD-GelMA double-network hydrogel wound dressing.

[0142] In this example, the concentration of GelMA is 10 wt% of the total mass of the prepolymer solution, the concentration of SD is 2 wt% of the total mass of the prepolymer solution, and the crosslinking ultraviolet wavelength is 420 nm. The mechanical properties of the hydrogel wound dressing are tested by tensile testing. The tensile strength of the SD-GelMA hydrogel wound dressing prepared in this example is 97.67 KPa, and the tensile strain is 75.11 times.

[0143] In summary of Examples 7 and 8, as the ultraviolet crosslinking wavelength increases, the strain increases and the stress decreases. This is because as the long wavelength increases, the crosslinking degree of the hydrogel crosslinked by ultraviolet light is relatively low, and the network structure is relatively loose, making it easier to deform under external force. Therefore, when the wavelength is too long, the energy of the ultraviolet light is not sufficient to stimulate an effective crosslinking reaction, resulting in a loose internal network structure of the hydrogel and a decrease in strength and stiffness. The combined effect of these factors leads to a decrease in the stress and an increase in the strain of the hydrogel.

[0144] In summary of the results of the above examples, Example 3 with a GelMA concentration of 10 wt%, an SD concentration of 2 wt%, and an ultraviolet crosslinking wavelength of 365 nm is selected as the subsequent ratio for the experiment.

[0145] To further prove the beneficial effects of the present invention and better understand the present invention, the following comparative examples and experiments are used to further clarify the technical features disclosed in the present invention, but it should not be construed as a limitation of the present invention. For other improvements made by those skilled in the art based on the above-mentioned inventive content without creative work, they are also considered to fall within the protection scope of the present invention.

[0146] Comparative Example 1: Preparation of GelMA single-network hydrogel

[0147] (1) Synthesis of gelatin (GelMA) monomer modified with methacrylic anhydride (MA):

[0148] 1) Dissolve gelatin (10 g, 0.2 mmol) in PBS buffer solution (pH 7.5) at 50 °C and stir (stirring rate: 500 - 800 rpm) for 2 h to obtain a 10% gelatin aqueous solution;

[0149] 2) Add analytically pure MA (0.5 g, 3.24 mmol) to the solution in step 1), and the mass ratio of MA to the solution in step 1) is 1:20. Continue to stir at 500 - 800 rpm at room temperature for 3 h;

[0150] 3) Add distilled water to the solution in step 2) to quench the reaction, obtaining a crude product;

[0151] 4) Purify the crude product using a dialysis bag (3500D), collect the product, and dialyze it for 7 days at 40 °C, changing the water regularly, 3 times a day;

[0152] 5) Place the solution in step 4) into a freeze dryer and freeze-dry it at -60 °C to obtain GelMA monomer. (2) Preparation of GelMA single-network hydrogel:

[0153] 1) Dissolve GelMA (0.5 g, 0.01 mmol) and I-184 photoinitiator (0.05 g, 0.02 mmol) in 4.45 g of pure water, and stir (stirring rate: 500 - 800 rpm) at 50 °C for 45 min to dissolve;

[0154] 2) Inject the prepolymer solution into a self-made glass mold with dimensions of 4 × 4 × 0.1 cm in length, width, and height through an injector, and let it cool naturally to room temperature;

[0155] 3) Transfer the mold in step 2) to an ultraviolet lamp with a wavelength of 365 nm and irradiate it for 1 h. Through the photoinitiated polymerization reaction, a hydrogen-bond crosslinked first-network gel of GelMA polymerization is formed.

[0156] The tensile strength of the GelMA single-network hydrogel prepared in this comparative example is 11.76 Kpa, and the tensile strain is 70.69%.

[0157] Comparative Example 2: Preparation of SD single-network hydrogel

[0158] (1) Synthesis of sodium alginate (SD) monomer modified with dopamine hydrochloride (DA):

[0159] 1) Dissolve sodium alginate (0.5 g, 2.31 mmol) in pure water at 25 °C, and stir (stirring rate: 500 - 800 rpm) for 12 h to obtain a 2% aqueous sodium alginate solution;

[0160] 2) Add 5 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) with a purity of 98% and 5 mmol of N-hydroxysuccinimide (NHS) with a purity of 98% to the solution in step 1), then adjust the pH to 5 - 6, and continue to stir at 500 - 800 rpm at room temperature for 1 h;

[0161] 3) Add 5 mmol of dopamine hydrochloride (DA) with a purity of 98% to the solution in step 2), and stir (stirring rate: 500 - 800 rpm) at room temperature for 24 h to obtain a crude product;

[0162] 4) Purify the crude product using a dialysis bag (3500D) and dialyze for 3 days at room temperature;

[0163] 5) Place the solution from step 4) after dialysis into a freeze dryer and freeze-dry at -60 °C to obtain the SD monomer modified with dopamine hydrochloride (DA).

[0164] (2) Preparation of SD single-network hydrogel:

[0165] Thoroughly mix SD (0.10 g, 0.46 mmol) with a saturated solution of CaCl2 with a purity of 98% and perform ionic crosslinking at room temperature for 30 min to form a network of ionic crosslinking between sodium alginate and calcium ions. Finally, obtain the SD single-network hydrogel.

[0166] The tensile strength of the SD single-network hydrogel prepared in this comparative example was 139.13 KPa, and the tensile strain was 99.82%.

[0167] Determination experiment:

[0168] To verify the successful graft modification of SD and GelMA, a nuclear magnetic resonance spectrometer (Bruker Avance NEO 600) was used to characterize sodium alginate and gelatin before and after modification. As Figure 4 shown, compared with SA, new peaks appeared in SD prepared by graft modification. This can be attributed to the vibration peaks of protons on the aromatic ring (6.6 - 6.7 ppm) of dopamine introduced into SD and the vibration peaks of protons on the amide bond (-HC=N-) formed by the dehydration condensation of the amino group of DA and the carboxyl group of SA (6.79 ppm). The above results indicate that dopamine hydrochloride was successfully grafted onto the SA molecular chain. Gel modification is the acylation reaction of MA with the amino group of Gel to form an amide bond, thereby obtaining GelMA. In Figure 4 GelMA, compared with Gel, obvious proton vibrations appeared at 5.33 ppm and 5.56 ppm, which can be attributed to the two proton peaks on the carbon-carbon double bond of MA, indicating that MA was successfully grafted onto the gelatin molecular chain.

[0169] To further verify the successful graft modification of SD and GelMA, as Figure 5 shown, a Fourier transform infrared spectrometer (BRUKE, VERTEX 70, Germany) was used to further verify the successful graft modification of SD and GelMA. The results are as Figure 5 (a) shown, the amide characteristic peak is at 1740 cm -1 and the stretching vibration peak of the -OH group is at 3410 cm -1 , which is also due to the stretching vibration of N-H. The peak at 1610 cm -1 is the bending vibration of N-H, and the peak at 1420 cm -1The peak at [location] is the bending vibration of C-H. According to the molecular formula of SD, the absorption peaks appearing in the FTIR spectrum correspond to the characteristic functional groups of SD, indicating the successful modification of SA. As Figure 5 (b) shows, at 1640 cm -1 , it is the characteristic peak of amide, and at the same time, it also corresponds to the characteristic peak of C=C; at 3400 cm -1 , the stretching vibration peaks of O-H and N-H are observed; at 2950 cm -1 , the peak is the stretching vibration of C-H, at 1540 cm -1 , the peak is the bending vibration of N-H, and at 1440 cm -1 , the peak is the bending vibration of C-H. According to the molecular formula of GelMA hydrogel, the absorption peaks appearing in the FTIR spectrum correspond to the characteristic functional groups of GelMA, indicating the successful synthesis of GelMA.

[0170] The SD-GelMA hydrogel wound dressing prepared in Example 3 was subjected to a tensile mechanical experiment, and the tensile stress and strain of the SD-GelMA hydrogel were measured to be 90.02 KPa and 120.67% respectively, indicating that the hydrogel dressing has good mechanical properties.

[0171] As Figure 6 shown, the fracture stress of the SD-GelMA double-network hydrogel wound dressing is generally higher than that of the GelMA single-network gel and the SD single-network hydrogel. This result shows that by introducing a double-network gel through graft modification, the mechanical properties of the hydrogel can be effectively improved. At the same time, the hydrogel dressing prepared by this method also has high biocompatibility and antibacterial properties, and has great prospects and potential in skin wound healing.

[0172] The SD-GelMA double-network hydrogel wound dressing prepared in Example 3 was subjected to an in vitro bacteria experiment. The antibacterial zone experiment was carried out using E. coli and S. aureus. After culturing for 12 h, antibacterial zones were formed around the samples, and the diameters of the antibacterial zones were 2 cm and 1 cm respectively, indicating that the hydrogel has good antibacterial effects on S. aureus and E. coli.

[0173] The SD-GelMA double-network hydrogel wound dressing prepared in Example 3 was subjected to a cell cytotoxicity experiment. According to GB / T16886.12-2017, the cell cytotoxicity was measured by the CCK-8 method. After culturing for 24 h, the cell survival rate was as high as 88%, indicating that the hydrogel dressing has no cell cytotoxicity.

[0174] The effect of the SD-GelMA double-network hydrogel dressing prepared in Example 3 on wound healing was evaluated. A skin wound model was constructed using balb / c mice to determine the efficacy of the SD-GelMA hydrogel dressing. Photos of the wound were taken at regular intervals to observe the wound healing process. The experimental results showed that the SD / GelMA hydrogel dressing had a promoting effect on wound healing and could promote the formation of blood vessels and hair follicles.

[0175] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A double network hydrogel based on sodium alginate / gelatin, characterized in that: The hydrogel has a porous structure with a pore diameter of 10-30 μm; and in the hydrogel, the mass concentration of gelatin is 10wt% to 20wt%, and the mass concentration of sodium alginate is 1wt% to 2wt%.

2. A method for preparing a double network hydrogel based on sodium alginate / gelatin as claimed in claim 1, characterized in that: The following steps are involved: (1) Synthesis of methacrylic anhydride (MA)-modified gelatin (GelMA) monomer; (2) Synthesizing sodium alginate (SD) monomer modified with dopamine hydrochloride (DA); (3) The grafted modified GelMA monomer and SD monomer are subjected to UV photopolymerization and ionic crosslinking to prepare a hydrogel dressing based on the SD / GelMA double network.

3. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 2, characterized in that: In step (1), the specific operation of synthesizing methacrylic anhydride (MA)-modified gelatin (GelMA) monomer is as follows: 1) dissolving gelatin in a PBS buffer solution with a pH of 4-9 at 30-70° C., stirring at a rate of 500-800 rpm for 2 h to obtain a gelatin aqueous solution; 2) adding the methacrylic anhydride (MA) solution to the gelatin aqueous solution prepared in step 1), and continuing to stir at 500-800 rpm for 3 h at room temperature for later use; 3) adding distilled water to the solution prepared in step 2) to quench the reaction to obtain a crude product; 4) Purify the crude product with a dialysis bag (2000-7000D) and dialyze at 20-50°C for 3-10 days, changing the water regularly, 2-5 times a day; 5) placing the dialyzed solution in step 4) into a freeze dryer and freeze drying it at -80 to -40°C to finally obtain the methacrylic anhydride (MA)-modified gelatin (GelMA) monomer.

4. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 3, characterized in that: The mass ratio of gelatin to PBS buffer solution was 1:9, and the mass ratio of gelatin aqueous solution to MA solution was 20:

1.

5. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 2, characterized in that: In step (2), the specific operation of synthesizing the sodium alginate (SD) monomer modified by dopamine hydrochloride (DA) is as follows: 1) dissolving sodium alginate in pure water at 20-30° C., stirring (stirring rate: 500-800 rpm) for 6-24 hours to obtain a sodium alginate aqueous solution; 2) Add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to the sodium alginate aqueous solution, then adjust the pH to 5-6, continue stirring at 500-800 rpm for 0.5-4 h at room temperature, and set aside; 3) adding dopamine hydrochloride (DA) to the solution prepared in step 2), stirring at 500-800 rpm for 12-48 hours at room temperature to obtain a crude product; 4) Purify the crude product using a dialysis bag (2000-7000D) and dialyze at room temperature for 3-10 days; 5) placing the dialyzed solution in step 4) into a freeze dryer and freeze drying it at -80 to -40°C to finally obtain sodium alginate (SD) monomer modified with dopamine hydrochloride (DA).

6. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 5, characterized in that: The mass ratio of sodium alginate to pure water is 1:49, and the molar ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and dopamine hydrochloride (DA) is 1:1:

1.

7. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 2, characterized in that: In step (3), the specific operation of preparing the hydrogel dressing based on the SD / GelMA double network is as follows: 1) Dissolve the synthesized methacrylic anhydride (MA)-modified gelatin GelMA monomer and I-184 photoinitiator in pure water, and stir and dissolve at 500-800 rpm for 30-120 min at 30-70° C.; 2) adding the synthesized dopamine hydrochloride (DA)-modified sodium alginate SD monomer to the solution of step 1), and continuing to stir and dissolve at 500-800 rpm at 30-70° C. for 1-6 hours until the solution is completely dissolved; 3) removing tiny bubbles from the solution in step 2) by ultrasound (ultrasonic power is 100%) to obtain a prepolymer solution; 4) The prepolymer solution was injected into a homemade glass mold with a length, width and height of 4×4×0.1 cm and cooled naturally to room temperature; 5) transferring the mold of step 4) to an ultraviolet lamp with a wavelength of 280-420 nm and irradiating it for 0.5-2 h to form a first network gel of hydrogen-bonded cross-linked GelMA polymerization through a photo-induced polymerization reaction; 6) placing the gel from step 5) in a CaCl2 solution for ion cross-linking at room temperature for 10 to 120 minutes to form a second network of sodium alginate and calcium ions cross-linked, so as to finally obtain a hydrogel dressing prepared by a grafted modified material, which is named SD-GelMA double network hydrogel, that is, the double network hydrogel based on sodium alginate / gelatin.

8. The method for preparing a double network hydrogel based on sodium alginate / gelatin according to claim 7, characterized in that: The mass ratio of GelMA monomer, I-184 photoinitiator and SD monomer is 10-20:1:1-4.

9. Use of the sodium alginate / gelatin based double network hydrogel according to claim 1 or the sodium alginate / gelatin based double network hydrogel prepared by the method according to claim 2 in the medical field.

10. The use according to claim 9, characterized in that: The sodium alginate / gelatin-based double-network hydrogel is a medical-grade hydrogel and can be used as a medical dressing.

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