Conductive self-healing collagen-based composite hydrogel and preparation method thereof

Abstract

The invention discloses conductive self-healing collagen-based composite hydrogel and a preparation method thereof, and belongs to the technical field of collagen-based materials. Natural collagen with good biological activity and biocompatibility, oxidized polysaccharide, 1, 4-phenylenediboronic acid and a conductive material are used as main raw materials, and the conductive material is prepared by virtue of an imine bond formed by an aldehyde group of the oxidized polysaccharide and an amino group of the collagen and the 1, 4-phenylenediboronic acid. A dynamic reversible double-crosslinking bond system is constructed by boric acid ester bonds formed between 1, 4-benzene diboronic acid and oxidized polysaccharide hydroxyl groups, so that the collagen hydrogel is endowed with self-healing property; meanwhile, a conductive material is introduced to prepare the conductive self-healing collagen-based composite hydrogel. The problems that an existing preparation method for the self-healing property of collagen and polysaccharide composite hydrogel only depends on a single type of dynamic bonds, the self-healing property of the hydrogel is not high, the service life is shortened due to the fact that the hydrogel cannot be quickly self-healed after being damaged by the external environment, the conductivity is poor, and electric signals cannot be effectively conducted are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of collagen-based materials, and particularly relates to a conductive self-healing collagen-based composite hydrogel and a preparation method thereof. Background Art

[0002] Collagen hydrogel not only has excellent biocompatibility, biodegradability and cell proliferation promotion effects, but also contains a large number of hydrophilic groups in collagen and the three-dimensional network structure of the hydrogel. Since a large amount of water is filled in the hydrogel polymer network, the whole material has the property of a fluid. Its soft and wet surface greatly reduces the irritation of the material to the surrounding tissues, thereby endowing the hydrogel with good tissue affinity and biocompatibility, and is a potential raw material for preparing wound dressings.

[0003] However, the pure collagen hydrogel cannot self-heal after being damaged by the external environment, which easily leads to the disadvantage of shortened service life, and even has an adverse effect on other non-lesioned tissues. Therefore, it is necessary to modify it to endow the collagen hydrogel with self-healing properties. At present, the modification methods for pure collagen hydrogels mainly rely on dynamic chemical interactions, that is, reversible non-covalent bonds (such as hydrogen bond interactions and hydrophobic association interactions, etc.). However, in this modification method, the bond energy of the reversible non-covalent bond is relatively low, resulting in the weak strength of the prepared hydrogel, which is difficult to withstand large external forces or deformations. In addition, although the hydrogel has a certain self-healing ability, the self-healing speed is slow, and the strength recovery after self-healing is limited, making it difficult to effectively cope with the damage of the external environment.

[0004] In the existing modification methods of pure collagen hydrogels, polysaccharides are used as raw materials. As natural macromolecular compounds, polysaccharides are widely sourced and have good biocompatibility. Some polysaccharides also have certain biological properties. For example, hyaluronic acid can treat arthritis and accelerate wound healing; carboxymethyl cellulose has the functions of stabilizing blood sugar and reducing cholesterol, so it has a wide range of applications in the food and biomedical fields. At present, the preparation method for the self-healing property of the collagen-polysaccharide composite hydrogel is mainly to oxidize the polysaccharide to obtain an oxidized polysaccharide containing aldehyde groups, and construct dynamic cross-linked imine bonds between it and the collagen amino group; however, this preparation method only relies on a single type of dynamic bond, that is, the imine bond to endow the hydrogel with self-healing properties, and the self-healing property of the prepared composite hydrogel is not strong, and it cannot effectively cope with the damage of the external environment.

[0005] In addition, the repair of wounds also depends on the conduction of physiological electrical signals therein. Therefore, if a wound dressing has good conductivity, it can not only promote wound repair, but also be used for wound monitoring. However, the pure collagen hydrogel has poor conductivity and cannot effectively conduct electrical signals. Summary of the Invention

[0006] To overcome the above-mentioned drawbacks of the prior art, the object of the present invention is to provide a conductive self-healing collagen-based composite hydrogel and a preparation method thereof, so as to solve the technical problems that the existing preparation methods for the self-healing property of collagen and polysaccharide composite hydrogels only rely on a single type of dynamic bond, resulting in weak self-healing property of the prepared composite hydrogel, inability to effectively cope with the damage of the external environment, and poor conductivity, and inability to effectively conduct electrical signals.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a preparation method of a conductive self-healing collagen-based composite hydrogel, which includes dissolving a collagen sponge in a sodium salt solution to obtain a collagen solution; dissolving an oxidized polysaccharide and a reducing agent in a sodium salt solution at room temperature, adding a conductive material, and obtaining an oxidized polysaccharide conductive dispersion after stirring and ultrasonic treatment; dissolving 1,4-benzenediboronic acid in a sodium salt solution, and obtaining a 1,4-benzenediboronic acid solution after adjusting the pH value; adding the oxidized polysaccharide conductive dispersion to the collagen solution for reaction, then adding the 1,4-benzenediboronic acid solution, and obtaining a conductive self-healing collagen-based composite hydrogel after stirring and standing.

[0008] Preferably, the conductive material is MXene, and the reducing agent is sodium ascorbate.

[0009] Preferably, the specific steps of the above preparation method of the conductive self-healing collagen-based composite hydrogel include: S1: Dissolving a collagen sponge in a sodium salt solution to obtain a collagen solution, and controlling the temperature at 2-10 °C; S2: Dissolving an oxidized polysaccharide and sodium ascorbate in a sodium salt solution at room temperature, stirring until completely dissolved, adding MXene, stirring for 10-20 min and ultrasonic dispersing for 30-60 min to obtain an oxidized polysaccharide conductive dispersion; S3: Dissolving 1,4-benzenediboronic acid in a sodium salt solution, and adjusting the pH value to obtain a 1,4-benzenediboronic acid solution; S4: Adding the oxidized polysaccharide conductive dispersion to the collagen solution, stirring for 2-6 h, then adding the 1,4-benzenediboronic acid solution, stirring for 1-3 h, controlling the temperature at 2-10 °C, and controlling the pH value at 8-10; then standing to form a gel to obtain a conductive self-healing collagen-based composite hydrogel, controlling the standing time at 3-24 h, and controlling the temperature at 20-35 °C.

[0010] Further preferably, in steps S1, S2 and S3, the sodium salt solution is one or two of a sodium chloride solution or a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, and the more preferred sodium salt solution is a mixed solution of a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution and a sodium chloride solution.

[0011] Further preferably, in steps S1, S2 and S3, the total salt molar concentration in the sodium salt solution is 90 - 180 mmol / L, and more preferably 110 - 135 mmol / L. The sodium chloride solution and the disodium hydrogen phosphate - sodium dihydrogen phosphate buffer can adjust the ionic strength of the system and affect the solubility of collagen. An appropriate ionic strength can effectively promote the dissolution of collagen. However, when the salt solution concentration is too high, the high ionic strength will cause salting - out of collagen and reduce its solubility.

[0012] Further preferably, in step S1, the mass percentage concentration of the collagen solution is 0.7% - 2.0%, and more preferably 1.0% - 1.6%. If the collagen concentration is too low, the formed gel network is sparse and unstable, and it is impossible to form a hydrogel or the mechanical properties of the formed hydrogel are poor; while if the concentration is too high, the viscosity of the system is too high, and it is not easy to form a uniform cross - linked system. This concentration range can not only ensure that the collagen hydrogel has certain mechanical properties, but also prevent the system viscosity from being too high, effectively meeting the experimental requirements.

[0013] Further preferably, in step S2, the raw materials of the oxidized polysaccharides, namely oxidized carboxymethyl cellulose, oxidized sodium alginate and oxidized hyaluronic acid, are all natural biomaterials, which have good biocompatibility and biodegradability, and form dynamic reversible cross - link bonds with 1,4 - phenylenediboronic acid, endowing the hydrogel with self - healing properties.

[0014] Further preferably, in step S2, the mass percentage concentration of the oxidized polysaccharide is 0.4% - 5.0%, and more preferably 1.0% - 3.0%.

[0015] Further preferably, in step S2, the mass percentage concentration of sodium ascorbate is 0.02% - 0.05%, and more preferably 0.03% - 0.04%; as a reducing agent, sodium ascorbate can effectively prevent the oxidation of MXene in aqueous solution and maintain its conductivity and stability.

[0016] Further preferably, in step S2, the mass percentage concentration of MXene is 0.4% - 5.0%, and more preferably 1.5% - 3.6%. A reasonable concentration range can not only ensure that the hydrogel has good conductivity, but also enable the conductive material to be evenly dispersed in the solution and avoid aggregation. When the MXene concentration is too low, it is not sufficient to endow the hydrogel with good conductive properties; when the concentration is too high, the conductive material cannot be evenly dispersed in the sodium salt solution, and the aggregation phenomenon will cause an increase in local stress of the hydrogel and a decrease in mechanical properties.

[0017] Further preferably, in step S3, the mass percentage concentration of 1,4-benzenediboronic acid is 1.0% - 3.0%, and more preferably, the mass percentage concentration of 1,4-benzenediboronic acid is 1.5% - 2.5%. If the concentration is too low, the concentration of collagen in the system will be reduced after addition, affecting the mechanical properties of the hydrogel; if the concentration is too high, 1,4-benzenediboronic acid cannot be dissolved in the sodium salt solution.

[0018] Further preferably, in step S3, the pH value of the 1,4-benzenediboronic acid solution is 9 - 11, and more preferably, the pH value of the solution is 9.5 - 10.5. When the pH value is too low, 1,4-benzenediboronic acid cannot be fully dissolved in the sodium salt solution; when the pH value is too high, collagen is prone to hydrolysis, losing its triple helix structure and resulting in a reduction in its biological function.

[0019] Further preferably, in step S4, the mass ratio of collagen, oxidized polysaccharide to 1,4-benzenediboronic acid in the conductive self-healing collagen-based composite hydrogel is 1:(0.8 - 2.5):(0.4 - 2.5), and more preferably, the mass ratio is 1:(1.0 - 2.0):(1.0 - 2.0). By controlling the mass ratio of each component, the hydrogel is ensured to have the best mechanical strength, self-healing property and conductivity. A reasonable mass ratio can ensure the formation of dynamic cross-linking bonds, improving the stability and durability of the hydrogel. When the dosages of oxidized polysaccharide and 1,4-benzenediboronic acid are too small, there are fewer dynamic covalent bonds in the system, making it difficult to endow the hydrogel with good self-healing property; when the dosages are too large, there will be a large amount of modifier residues, wasting materials and affecting the biocompatibility of the materials.

[0020] Further preferably, in step S4, the pH value is controlled at 8 - 10, and more preferably, the pH value is 8.5 - 9.5. In this pH value range, the reaction activity of 1,4-benzenediboronic acid is higher, and it can more effectively form cross-linking bonds with oxidized polysaccharide and collagen, thereby improving the self-healing property and mechanical properties of the hydrogel.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a conductive self-healing collagen-based composite hydrogel. Oxidized polysaccharide and 1,4-benzenediboronic acid are used to modify the collagen hydrogel, and a dynamic reversible double-crosslinking system is constructed to endow the collagen hydrogel with self-healing properties. First, dynamic crosslinking imine bonds are formed between the oxidized polysaccharide and the amino groups of the collagen solution. These bonds can quickly break and reform when damaged. At the same time, the polysaccharide contains a large number of ortho-hydroxy groups, which can form reversible borate ester bonds with the borate groups of the 1,4-benzenediboronic acid solution. These bonds also have the ability to quickly break and reform. Thus, a dynamic reversible double-crosslinking bond system is constructed, endowing the collagen-based composite hydrogel with excellent self-healing properties. The synergistic effect of imine bonds and borate ester bonds not only improves the mechanical strength of the hydrogel but also significantly enhances its self-healing performance. Compared with hydrogels that solely rely on non-covalent bonds, the dynamic reversible double-crosslinking bond system can quickly achieve self-healing, and the mechanical properties after self-healing are more significantly restored. Second, the preparation method of the present invention prepares the collagen composite hydrogel under low-temperature or room-temperature conditions, maintaining the triple-helix structure of natural collagen to fully exert its excellent biological properties. Finally, on the basis of realizing the self-healing property of the collagen hydrogel, powders with good conductivity are introduced to prepare a conductive self-healing collagen-based composite hydrogel, thereby endowing the collagen hydrogel with certain conductivity and improving the mechanical properties of the collagen hydrogel. Description of the Drawings

[0022] Figure 1 Continuous step strain sweep curve of the conductive self-healing collagen composite hydrogel prepared in Example 1; Figure 2 Self-healing photo of the conductive self-healing collagen composite hydrogel prepared in Example 2; Figure 3 Conductivities of the conductive self-healing collagen composite hydrogels prepared in Comparative Example 1, Example 3, and Example 5; Figure 4 Conductivity photo of the conductive self-healing collagen composite hydrogel prepared in Example 4; Figure 5 Remolding and adhesion photos of the conductive self-healing collagen composite hydrogel prepared in Example 1. Detailed Description of the Invention

[0023] To enable those skilled in the art to understand the features and effects of the present invention, the following provides only a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definition in this specification shall prevail.

[0024] The theories or mechanisms described and disclosed herein, whether right or wrong, shall not in any way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0025] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0026] In this document, unless otherwise specified, the terms "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0027] In this document, for the sake of brevity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as being within the scope described in this specification.

[0028] In the present invention, the collagen sponge is prepared by the following method: Fresh cowhide is pretreated by hair removal, degreasing, etc. and then chopped, and then placed in a 0.5 mol / L acetic acid solution containing 3% pepsin (EC 1:10000) for extraction. It is centrifuged for 10 min using a high-speed refrigerated centrifuge to separate the supernatant. The precipitate obtained after salting out with sodium chloride and centrifugation is dissolved again in a 0.5 mol / L acetic acid solution, and the dissolved collagen is dialyzed with a 0.1 mol / L acetic acid solution for three days, changing the dialysis solution every 12 h. Finally, the collagen solution is freeze-dried, and the obtained collagen sponge after freeze-drying is placed in a desiccator for storage and standby.

[0029] In the present invention, the conductive material MXene is prepared by the following method: First, 20 mL (12 mol / L) of hydrochloric acid solution is placed in a polytetrafluoroethylene container, and 1.6 g of lithium fluoride is slowly added until dissolved. Then, 1 g of aluminum titanium carbide is slowly added to the above solution and stirred at 42 °C for 24 h within 1 h. After the reaction, the product is washed repeatedly with deionized water until the pH of the supernatant is close to neutral. The product is centrifuged and collected, dispersed in deionized water, ultrasonically treated for 6 h under the protection of argon gas environment, centrifuged (3500 × g) for 10 min to obtain a dark green supernatant, and freeze-dried and then stored in a refrigerator for standby.

[0030] In the present invention, the oxidized polysaccharide is prepared by the following method: adding the polysaccharide into deionized water, adjusting the pH value to 2 with dilute sulfuric acid after stirring and completely dissolving, adding sodium periodate with the same mass as the polysaccharide, reacting at 35 °C in the dark for 5 h, and freeze-drying after purification by alternating washing with ethanol / water to obtain the oxidized polysaccharide.

[0031] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0032] Conventional instrument and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions indicated in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, “%” represents weight percentage, “parts” represents weight parts, and the ratio represents weight ratio.

[0033] Example 1 The collagen sponge was dissolved in a mixed solution of 10 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution and 100 mmol / L sodium chloride solution at 8 °C to prepare a 0.7% collagen solution. The oxidized hyaluronic acid and sodium ascorbate were dissolved in a mixed solution of 10 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution and 100 mmol / L sodium chloride solution, wherein the mass concentration of oxidized hyaluronic acid was 2.0% and the mass concentration of sodium ascorbate was 0.02%; then MXene was added to the above solution, stirred for 15 min and ultrasonically dispersed for 40 min to prepare an oxidized hyaluronic acid conductive dispersion, wherein the MXene concentration was 1.0%; 1,4-benzenediboronic acid was dissolved in a mixed solution of 10 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution and 100 mmol / L sodium chloride solution, and the pH value was adjusted to 9 to obtain a 1,4-benzenediboronic acid solution, wherein the mass concentration of 1,4-benzenediboronic acid was 1.5%. The oxidized hyaluronic acid conductive dispersion was added to the collagen solution, stirred for 2 h, then the 1,4-benzenediboronic acid solution was added, and stirred for 2 h, the temperature was controlled at 8 °C, and the pH value was controlled at 8; the mass ratio of collagen, oxidized hyaluronic acid and 1,4-benzenediboronic acid in the mixed solution was 1:1.8:0.8. Subsequently, it was left to gel to obtain a conductive self-healing collagen-based composite hydrogel, and the standing time was controlled at 3 h and the temperature was controlled at 30 °C.

[0034] Example 2 Dissolve the collagen sponge in 180 mmol / L sodium chloride solution at 6 °C to prepare a 1.3% collagen solution. Dissolve oxidized sodium alginate and sodium ascorbate in 180 mmol / L sodium chloride solution, where the mass concentration of oxidized sodium alginate is 2.7%; the mass concentration of sodium ascorbate is 0.03%; then add MXene to the above solution, stir for 10 min and ultrasonically disperse for 30 min to obtain an oxidized sodium alginate conductive dispersion, where the MXene concentration is 0.4%; dissolve 1,4-phenylenediboronic acid in 180 mmol / L sodium chloride solution, and adjust the pH value to 10 to obtain a 1,4-phenylenediboronic acid solution. The mass concentration of 1,4-phenylenediboronic acid is 2.0%. Add the oxidized sodium alginate conductive dispersion to the collagen solution, stir for 3 h, then add the 1,4-phenylenediboronic acid solution, stir for 1 h, control the temperature at 6 °C and the pH value at 9; the mass ratio of collagen, oxidized sodium alginate and 1,4-phenylenediboronic acid in the mixture is 1:2.1:1.3. Then let it stand to form a gel to obtain a conductive self-healing collagen-based composite hydrogel, and control the standing time at 5 h and the temperature at 25 °C.

[0035] Example 3 Dissolve the collagen sponge in 100 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution at 4 °C to prepare a 2.0% collagen solution. Dissolve oxidized carboxymethyl cellulose and sodium ascorbate in 100 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, where the mass concentration of oxidized carboxymethyl cellulose is 0.6%; the mass concentration of sodium ascorbate is 0.04%; then add MXene to the above solution, stir for 12 min and ultrasonically disperse for 45 min to obtain an oxidized carboxymethyl cellulose conductive dispersion, where the MXene concentration is 2.7%; dissolve 1,4-phenylenediboronic acid in sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution, and adjust the pH value to 11 to obtain a 1,4-phenylenediboronic acid solution. The mass concentration of 1,4-phenylenediboronic acid is 1.0%. Add the oxidized carboxymethyl cellulose conductive dispersion to the collagen solution, stir for 4 h, then add the 1,4-phenylenediboronic acid solution, stir for 2 h, control the temperature at 4 °C and the pH value at 10; the mass ratio of collagen, oxidized carboxymethyl cellulose and 1,4-phenylenediboronic acid in the mixture is 1:0.8:0.4. Then let it stand to form a gel to obtain a conductive self-healing collagen-based composite hydrogel, and control the standing time at 10 h and the temperature at 20 °C.

[0036] Example 4 The collagen sponge was dissolved in 90 mmol / L sodium chloride solution at 2 °C to prepare a 1.5% collagen solution. Sodium alginate oxide and sodium ascorbate were dissolved in 90 mmol / L sodium chloride solution, where the mass concentration of sodium alginate oxide was 5.0% and the mass concentration of sodium ascorbate was 0.03%. Subsequently, MXene was added to the above solution, stirred for 18 min and ultrasonically dispersed for 50 min to obtain a sodium alginate oxide conductive dispersion with an MXene concentration of 4.0%. 1,4-Phenylenediboronic acid was dissolved in sodium chloride solution, and the pH value was adjusted to 9.5 to obtain a 1,4-phenylenediboronic acid solution. The mass concentration of 1,4-phenylenediboronic acid was 3.0%. The sodium alginate oxide conductive dispersion was added to the collagen solution, stirred for 5 h, then the 1,4-phenylenediboronic acid solution was added, and stirred for 2 h. The temperature was controlled at 2 °C and the pH value was controlled at 8.5. The mass ratio of collagen, sodium alginate oxide to 1,4-phenylenediboronic acid in the mixture was 1:2.5:2.5. Subsequently, it was allowed to stand to form a gel to obtain a conductive self-healing collagen-based composite hydrogel, and the standing time was controlled at 15 h and the temperature was controlled at 32 °C.

[0037] Example 5 The collagen sponge was dissolved in a mixed solution of 10 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution and 125 mmol / L sodium chloride solution at 10 °C to prepare a 1.8% collagen solution. Oxidized carboxymethyl cellulose and sodium ascorbate were dissolved in a mixed solution of 10 mmol / L sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution and 125 mmol / L sodium chloride solution, where the mass concentration of oxidized carboxymethyl cellulose was 1.5%; the mass concentration of sodium ascorbate was 0.05%. Subsequently, MXene was added to the above solution, stirred for 20 min and ultrasonically dispersed for 60 min with an MXene concentration of 5.0% to obtain an oxidized carboxymethyl cellulose conductive dispersion. 1,4-Phenylenediboronic acid was dissolved in a sodium salt solution, and the pH value was adjusted to 10.5 to obtain a 1,4-phenylenediboronic acid solution. The mass concentration of 1,4-phenylenediboronic acid was 2.5%. The oxidized carboxymethyl cellulose conductive dispersion was added to the collagen solution, stirred for 6 h, then the 1,4-phenylenediboronic acid solution was added, and stirred for 3 h. The temperature was controlled at 10 °C and the pH value was controlled at 9.5. The mass ratio of collagen, oxidized carboxymethyl cellulose to 1,4-phenylenediboronic acid in the mixture was 1:1:1.2. Subsequently, it was allowed to stand to form a gel to obtain a conductive self-healing collagen-based composite hydrogel, and the standing time was controlled at 24 h and the temperature was controlled at 35 °C.

[0038] Comparative Example 1: The difference from Example 1 was that a collagen hydrogel was prepared without introducing MXene.

[0039] Figure 1Step strain sweep curves of the conductive self-healing collagen composite hydrogel prepared in Example 1. After three different strain alternations, the storage modulus of the collagen composite hydrogel can still return to the initial level. The results show that the prepared collagen composite hydrogel has the ability to quickly restore its original structural integrity and mechanical stability, showing good self-healing performance.

[0040] Figure 2 Self-healing photo of the conductive self-healing collagen composite hydrogel prepared in Example 2. The prepared collagen composite hydrogel was cut in the middle, and then the cut hydrogels were spliced together. The self-healing situation of the composite hydrogel was observed by standing at room temperature. After standing for a period of time, the hydrogel healed completely.

[0041] Figure 3 Conductivities of the conductive self-healing collagen composite hydrogels prepared in Comparative Example 1, Example 3 and Example 5. The conductivity of the collagen composite hydrogel shows a trend of first increasing and then gradually stabilizing with the increase of the MXene concentration, indicating that the introduction of MXene endows the hydrogel with good conductivity.

[0042] Figure 4 Conductivity photo of the conductive self-healing collagen composite hydrogel in Example 4. The prepared collagen hydrogel was connected to a closed circuit with a diode, and it was found that the diode could emit light stably, indicating that the hydrogel has excellent conductivity after adding MXene.

[0043] Figure 5 Remolding and adhesion of the conductive self-healing collagen composite hydrogel in Example 1. The prepared collagen composite hydrogel was adhered to leather and metal to observe its adhesion ability. It was found that the composite hydrogel had good adhesion on these materials and there was no residue after peeling, indicating that the hydrogel has good adhesion.

[0044] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a conductive self-healing collagen-based composite hydrogel, characterized in that: The method comprises dissolving a collagen sponge in a sodium salt solution to obtain a collagen solution; dissolving an oxidized polysaccharide and a reducing agent in a sodium salt solution at room temperature, adding a conductive material, stirring and ultrasonically treating, to obtain an oxidized polysaccharide conductive dispersion; dissolving 1, 4-phenylenediboric acid in a sodium salt solution, adjusting the pH value to obtain a 1, 4-phenylenediboric acid solution; adding the oxidized polysaccharide conductive dispersion to the collagen solution for reaction, then adding the 1, 4-phenylenediboric acid solution, stirring, and then standing to obtain a conductive self-healing collagen-based composite hydrogel.

2. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The specific steps are as follows: S1: dissolving the collagen sponge in a sodium salt solution to obtain a collagen solution with a mass percentage concentration of 0.7% to 2.0%, and controlling the temperature at 2 to 10°C; S2: dissolving the oxidized polysaccharide and the reducing agent in a sodium salt solution at room temperature, stirring until completely dissolved, adding the conductive material, stirring for 10 to 20 min and ultrasonically dispersing for 30 to 60 min to obtain an oxidized polysaccharide conductive dispersion; S3: dissolving 1, 4-phenyldiboric acid in a sodium salt solution, and adjusting the pH value to 9 to 11 to obtain a 1, 4-phenyldiboric acid solution; S4: Add the oxidized polysaccharide conductive dispersion to the collagen solution, stir and react for 2 to 6 hours, then add the 1, 4-phenyldiboric acid solution, stir and react for 1 to 3 hours, control the temperature at 2 to 10°C, and control the pH value at 8 to 10; then stand at 20 to 35°C for 3 to 24 hours to obtain a conductive self-healing collagen-based composite hydrogel.

3. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The reducing agent is sodium ascorbate; and the conductive material is MXene.

4. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The sodium salt solution includes one or two of a sodium chloride solution and a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution; the total salt molar concentration in the sodium salt solution is 90 mmol / L to 180 mmol / L.

5. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The oxidized polysaccharide is one of oxidized carboxymethyl cellulose, oxidized sodium alginate and oxidized hyaluronic acid.

6. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The mass percentage concentration of the collagen solution is 0.7% to 2.0%.

7. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The mass percentage concentration of the oxidized polysaccharide in the oxidized polysaccharide conductive dispersion is 0.6% to 5.0%; the mass percentage concentration of the reducing agent is 0.02% to 0.05%; and the mass percentage concentration of the conductive material is 0.4% to 5.0%.

8. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The mass percentage concentration of 1, 4-phenyldiboric acid is 1.0% ~ 3.0%.

9. The method for preparing a conductive self-healing collagen-based composite hydrogel according to claim 1, characterized in that: The mass ratio of collagen, oxidized polysaccharide and 1,4-phenylenediboronic acid in the conductive self-healing collagen-based composite hydrogel is 1:(0.8-2.5):(0.4-2.5).

10. The conductive self-healing collagen-based composite hydrogel prepared by the method for preparing a conductive self-healing collagen-based composite hydrogel according to any one of claims 1 to 9.

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