Antibacterial hydrogel and its preparation method and application

Abstract

The present invention discloses an antibacterial hydrogel and a preparation method and application thereof, wherein the antibacterial hydrogel comprises an interpenetrating network structure of at least three polymer networks; the interpenetrating network structure comprises: a first network formed by crosslinking polydopamine and gelatin; a second network formed by crosslinking polydopamine and chitosan; a third network formed by crosslinking chitosan and gelatin; wherein the first network, the second network and the third network are entangled with each other. The hydrogel provided by the present invention not only has the characteristics of biodegradability and excellent biocompatibility, but also has good antibacterial properties without the introduction of metal ions and antibiotics.

Description

Technical Field

[0001] The present invention relates to the field of biological antibacterial materials, and more specifically, to an antibacterial hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogel is a soft material with a three-dimensional network structure formed by cross-linking hydrophilic polymers and absorbing a large amount of water. Hydrogels are widely used in tissue engineering, wound dressings, drug release and other fields because they have both the mechanical properties of solids and the diffusion behavior of liquids. However, traditional hydrogels have disadvantages such as low swelling rate and relatively poor gel strength. Recent studies have found that interpenetrating networks are one of the most effective ways to improve the strength of hydrogels. Interpenetrating network gels are hydrogels formed by polymer networks entangled together through persistent topological interactions. Its unique forcing effect can enable a variety of polymers with very different properties or different functions to form a stable combination, thereby achieving complementary performance between components.

[0003] The problem of drug resistance caused by the abuse of antibiotics has always troubled people's lives. The emergence of antibacterial hydrogels has opened up a new way to solve the problem of antibiotic resistance. At present, most antibacterial hydrogels are usually hydrogels encapsulated with antibacterial drugs or antibacterial metal nanoparticles. This type of antibacterial hydrogel is prone to cause drug resistance or cause lesions due to the accumulation of metal ions in the internal organs. Therefore, the development of green, environmentally friendly and biocompatible antibacterial hydrogels has been a research hotspot in recent years.

[0004] Dopamine is a biological neurotransmitter and a catechol derivative of L-DOPA. Dopamine can undergo oxidative polymerization under alkaline aerobic conditions, and its polymerization product has certain antibacterial properties because it contains a large amount of catechol. Therefore, dopamine is a pure natural antibacterial agent, and it also has the advantages of good biocompatibility and easy degradation. However, the antibacterial hydrogels formed by traditional dopamine through physical or chemical methods have weak mechanical properties and poor antibacterial ability, which makes it difficult to meet the requirements of medical materials. Therefore, it is of great significance to develop a dopamine-based hydrogel with good biocompatibility, high antibacterial rate and good mechanical properties. Summary of the invention

[0005] The first object of the present invention is to provide an antibacterial hydrogel.

[0006] The second object of the present invention is to provide a method for preparing an antibacterial hydrogel.

[0007] The third object of the present invention is to provide an application of an antibacterial hydrogel.

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

[0009] In a first aspect, the present invention provides an antibacterial hydrogel, wherein the antibacterial hydrogel comprises an interpenetrating network structure of at least three polymer networks; the interpenetrating network structure comprises:

[0010] The first network formed by cross-linking of polydopamine and gelatin;

[0011] The second network formed by cross-linking polydopamine and chitosan;

[0012] The third network formed by cross-linking chitosan and gelatin;

[0013] The first network, the second network and the third network are intertwined with each other.

[0014] Furthermore, the raw materials of the antibacterial hydrogel include: dopamine hydrochloride, gelatin and chitosan; the mass ratio of dopamine hydrochloride, gelatin and chitosan is 15-25:5-10:1-3.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned antibacterial hydrogel, comprising the following steps:

[0016] dissolving dopamine hydrochloride in an alkaline buffer solution to perform self-polymerization to prepare a polydopamine solution;

[0017] Mix the pre-cooled polydopamine solution and gelatin solution in an ice bath for 3 to 10 minutes;

[0018] Under ice bath condition, chitosan solution and catalyst solution were added in sequence;

[0019] Carry out freezing and thawing to obtain the product.

[0020] Further, the freezing process includes:

[0021] First freezing: Freeze at 0~-5℃ for 6~8h;

[0022] Secondary freezing: Freeze at -5 to -10°C for 8 to 12 hours;

[0023] Three-stage freezing: Freeze at -10 to -15°C for 10 to 16 hours.

[0024] Furthermore, the concentration of the polydopamine solution is 1 to 10 wt %.

[0025] Furthermore, the concentration of the gelatin solution is 0.5 to 5 wt %.

[0026] Furthermore, the concentration of the chitosan solution is 0.15-1.5 wt%.

[0027] Furthermore, the catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS).

[0028] Furthermore, the concentration of EDC in the catalyst solution is 0.75-7.5 wt %, and the concentration of NHS is 0.45-4.5 wt %.

[0029] Furthermore, the alkaline buffer is a Tris buffer with a pH value of 8.5-9.

[0030] Furthermore, the solvent of the gelatin solution or chitosan solution or catalyst solution is selected from one of PBS buffer, MOPS buffer and HEPES buffer.

[0031] Preferably, the solvent of the gelatin solution or chitosan solution or catalyst solution is PBS buffer with a pH of 7-8.

[0032] In a third aspect, the present invention provides an application of the above-mentioned antibacterial hydrogel in the fields of biological scaffolds, cell culture, drug controlled release or tissue engineering.

[0033] In addition, unless otherwise specified, the raw materials used in the present invention can be obtained from commercial sources, and any range recorded in the present invention includes the end value and any value between the end values ​​and any sub-range formed by the end value or any value between the end values. The percentages are all mass percentages unless otherwise specified, and the solutions are all aqueous solutions unless otherwise specified.

[0034] The beneficial effects of the present invention are as follows:

[0035] (1) The antibacterial hydrogel provided by the present invention is structurally characterized by forming an interpenetrating network structure containing at least three polymer networks by various cross-linking reactions between amino, carboxyl, hydroxyl and other groups on polydopamine, gelatin and chitosan, and the hydrogen bonding forces formed therebetween. The interpenetrating network structure can not only improve the cross-linking degree, mechanical properties and stability of the hydrogel, but also have good antibacterial properties, biocompatibility and biodegradability without introducing metal ions or using antibiotics.

[0036] (2) The antibacterial hydrogel provided by the present invention uses polydopamine as the main antibacterial active ingredient in terms of raw materials, and is combined with a certain amount of chitosan and gelatin to synergistically improve the antibacterial activity of the hydrogel, while also improving its mechanical properties and stability.

[0037] (3) In the preparation method of the antibacterial hydrogel provided by the present invention, polydopamine and gelatin are first mixed for a certain period of time to allow them to undergo a certain degree of pre-crosslinking, which not only ensures that the hydrogel has polydopamine as the main chain, but also further improves the degree and uniformity of crosslinking of the hydrogel, thereby improving the antibacterial activity and mechanical properties of the hydrogel. Secondly, the present invention uses a staged freeze polymerization method during the final crosslinking, which can also further improve the mechanical properties and stability of the hydrogel.

[0038] (4) The preparation method of the antibacterial hydrogel provided by the present invention has a simple process, low production cost, and is easy for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0040] Figure 1 A physical picture of the antibacterial hydrogel prepared in Example 1 is shown.

[0041] Figure 2 The scanning electron microscope image of the antibacterial hydrogel prepared in Example 1 after freeze-drying is shown.

[0042] Figure 3 The figure shows the comparison of cell survival rates of mouse fibroblast L929 cells cultured using different hydrogels. DETAILED DESCRIPTION

[0043] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0044] There is no particular limitation on the purity of all raw materials in the present invention, and analytically pure materials are preferably used in the present invention.

[0045] The sources and abbreviations of all raw materials in the present invention are conventional sources and abbreviations in the field, and are clear and definite in the field of their relevant uses. Those skilled in the art can purchase them from commercial sources or prepare them by conventional methods based on the abbreviations and corresponding uses.

[0046] As used herein, the term "hydrogel" refers to a cross-linked polymeric material that exhibits the ability to swell in water or aqueous solutions without dissolving and to retain a significant portion of water or aqueous solutions within its structure.

[0047] The term "interpenetrating network" used in the present invention refers to an interpenetrating polymer network, which is a combination of two or more polymers wherein each two polymers are cross-linked to form a network. There are entanglements and interactions between the networks.

[0048] The antibacterial hydrogel provided by the present invention comprises an interpenetrating network structure of at least three polymer networks; the interpenetrating network structure comprises:

[0049] The first network formed by cross-linking of polydopamine and gelatin;

[0050] The second network formed by cross-linking polydopamine and chitosan;

[0051] The third network formed by cross-linking chitosan and gelatin;

[0052] The first network, the second network and the third network are intertwined with each other.

[0053] The antibacterial hydrogel of the present invention is mainly formed by crosslinking such as amidation reaction, Schiff base reaction, Michael addition reaction and hydrogen bond formation between amino groups, carboxyl groups and hydroxyl groups existing on polydopamine, gelatin and chitosan to form an interpenetrating and entangled network structure. The interpenetrating network structure has multiple crosslinking points, which not only improves the crosslinking degree, mechanical properties and stability of the hydrogel, but also the present invention unexpectedly finds that when polydopamine, chitosan and gelatin without antibacterial properties are crosslinked to form a gel, its antibacterial activity is much higher than the antibacterial activity of polydopamine and chitosan respectively crosslinked with gelatin to form a gel.

[0054] Furthermore, the raw materials of the antibacterial hydrogel include: dopamine hydrochloride, gelatin and chitosan; the mass ratio of dopamine hydrochloride, gelatin and chitosan is 15-25:5-10:1-3. Among them, the antibacterial hydrogel of the present invention uses dopamine as the main antibacterial component, and cooperates with a certain amount of chitosan and gelatin to synergistically improve the antibacterial activity of the hydrogel, while also improving its mechanical properties and stability. In addition, the present invention also found that if the amount of chitosan added is too high, it will affect the biocompatibility, elasticity and flexibility of the hydrogel. If the amount of chitosan added is too low, the antibacterial activity of the hydrogel will also decrease accordingly; and if the amount of gelatin added is too high, the gel is relatively viscous, and the gelatin fluidity and elasticity are not strong. If the amount of gelatin added is too low, it is difficult to gel.

[0055] Preferably, the raw materials of the antibacterial hydrogel include: dopamine hydrochloride, gelatin and chitosan; the mass ratio of dopamine hydrochloride, gelatin and chitosan is 15-18:7-9:1-2. The antibacterial performance of the antibacterial hydrogel of the present invention can be better when the proportion of each component is within the above range.

[0056] Preferably, the deacetylation of the chitosan is 80-95% and the viscosity is 50-800.

[0057] Furthermore, the present invention provides a method for preparing the above-mentioned antibacterial hydrogel, comprising the following steps:

[0058] dissolving dopamine hydrochloride in an alkaline buffer solution to perform self-polymerization to prepare a polydopamine solution;

[0059] Mix the pre-cooled polydopamine solution and gelatin solution in an ice bath for 3 to 10 minutes;

[0060] Under ice bath condition, chitosan solution and catalyst solution were added in sequence;

[0061] Carry out freezing and thawing to obtain the product.

[0062] Among them, polydopamine and gelatin are very easy to crosslink and form gel at room temperature. Therefore, the present invention mixes the precooled polydopamine solution and gelatin solution under ice bath conditions, preventing the large-scale gelation of polydopamine and gelatin, and by reasonably controlling the mixing time, regulating the pre-gelation degree of polydopamine and gelatin, ensuring the main chain structure of polydopamine in the hydrogel, the first network formed by the cross-linking of polydopamine and gelatin as the base, and reserving sufficient active sites for the cross-linking of chitosan and the remaining gelatin in the later stage. The preparation method of the present invention of sequential mixing and step-by-step gelation under specific conditions can also effectively improve the crosslinking degree and uniformity of the hydrogel, thereby helping to improve the mechanical properties and antibacterial properties of the final hydrogel.

[0063] Preferably, the precooling may be performed in an ice bath or in other refrigeration devices.

[0064] In addition, the cross-linking reaction that occurs during the freezing treatment uses polydopamine as a cross-linking agent and under the action of a catalyst, polydopamine reacts with the amino group and carboxyl group of gelatin to undergo a Schiff base reaction, a Michael addition reaction, and an amidation reaction to form a cross-linked network of polydopamine and gelatin with antibacterial effects. At the same time, the presence of a large number of hydroxyl groups and amino groups in chitosan molecules can further promote the cross-linking reaction and hydrogen bond formation in the system, thereby synergistically improving the stability and antibacterial activity of the antibacterial gel.

[0065] Preferably, the freezing treatment of the present invention adopts a staged polymerization method with gradually lowering the temperature. This method not only ensures a high degree of cross-linking of the hydrogel, but the present invention also unexpectedly finds that the staged polymerization can significantly improve the mechanical properties of the hydrogel compared to one-step polymerization within the same or even shorter reaction time.

[0066] Furthermore, in the above preparation method, the concentration of the polydopamine solution is 1 to 10 wt %.

[0067] The concentration of the gelatin solution is 0.5-5wt%.

[0068] The concentration of the chitosan solution is 0.15-1.5 wt %.

[0069] The catalysts are EDC and NHS.

[0070] The concentration of EDC in the catalyst solution is 0.75-7.5 wt %, and the concentration of NHS is 0.45-4.5 wt %.

[0071] Among them, the present invention has found that by configuring various raw material solutions within a specific concentration range and then mixing them in sequence for cross-linking, the gelling property and cross-linking uniformity of the hydrogel can be controlled, which is beneficial to improving the mechanical properties of the hydrogel.

[0072] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0073] Example 1

[0074] An antibacterial hydrogel and a preparation method thereof, comprising the following steps:

[0075] 1) 10 mmol of tris(hydroxymethyl)aminomethane was taken to prepare 30 mL of Tris buffer with a pH value of 8.5, and then 1.5 g of dopamine hydrochloride solid was added to the obtained Tris buffer, and stirred at room temperature for 48 h to obtain a Tris buffer of polydopamine;

[0076] 2) Take 0.75 g of gelatin, add it to 15 mL of PBS buffer (pH 7.4), and stir for 24 h to obtain gelatin PBS buffer;

[0077] 3) precooling the Tris buffer of polydopamine in step 1) in an ice bath, and then mixing and stirring with the PBS buffer of gelatin in step 2) in an ice bath for 5 minutes to obtain a clear prepolymer solution A; 4) weighing 0.12 g of chitosan (deacetylation is 80-95%), 2.25 g of EDC and 1.35 g of NHS, respectively adding them to 60 mL of PBS buffer (pH 7.4) and stirring evenly, then taking 5 mL of each of the three solutions in turn and adding them to the prepolymer solution A obtained in step 3), stirring in an ice bath to obtain a mixed solution B;

[0078] 5) The mixed solution B was transferred to a mold, polymerized at 0°C for 6 h, then at -5°C for 8 h, and finally at -10°C for 10 h. After thawing, the antibacterial hydrogel (such as Figure 1 The electron micrograph of the hydrogel after freeze-drying is shown in Figure 2 .

[0079] Example 2

[0080] An antibacterial hydrogel and a preparation method thereof, comprising the following steps:

[0081] 1) 10 mmol of tris(hydroxymethyl)aminomethane was taken to prepare 30 mL of Tris buffer with a pH value of 8.5, and then 1.8 g of dopamine hydrochloride solid was added to the obtained Tris buffer, and stirred at room temperature for 48 h to obtain a Tris buffer of polydopamine;

[0082] 2) Take 0.9 g of gelatin, add it to 18 mL of PBS buffer (pH 7.4), and stir for 24 h to obtain gelatin PBS buffer;

[0083] 3) precooling the Tris buffer of polydopamine in step 1) in an ice bath, and then mixing and stirring with the PBS buffer of gelatin in step 2) in an ice bath for 5 minutes to obtain a clear prepolymer solution A;

[0084] 4) Weigh 0.144 g of chitosan (80-95% deacetylation), 2.7 g of EDC and 1.62 g of NHS, add them to 60 mL of PBS buffer (pH 7.4) and stir evenly. Then take 5 mL of each of the three solutions and add them to the prepolymer solution A obtained in step 3), stir in an ice bath to obtain a mixed solution B;

[0085] 5) The mixed solution B was transferred to a mold, polymerized at -5°C for 8 h, then at -10°C for 12 h, and finally at -15°C for 16 h. The antibacterial hydrogel was obtained after thawing.

[0086] Comparative Example 1

[0087] A gelatin hydrogel, the preparation method of which comprises the following steps:

[0088] Take 1.0 g of gelatin, add it to 15 mL of PBS buffer (pH 7.4), stir for 24 hours, and let it stand until a gel is formed.

[0089] Comparative Example 2

[0090] A gelatin-polydopamine hydrogel, the preparation method of which comprises the following steps:

[0091] 1) 10 mmol of tris(hydroxymethyl)aminomethane was taken to prepare 30 mL of Tris buffer with a pH value of 8.5, and then 2 g of dopamine hydrochloride solid was added to the obtained Tris buffer, and stirred at room temperature for 48 h to obtain a Tris buffer of polydopamine;

[0092] 2) Take 1.0 g of gelatin, add it to 15 mL of PBS buffer (pH 7.4), and stir for 24 h to obtain gelatin PBS buffer;

[0093] 3) Mix the PBS buffer solution and gelatin in step 2) with the pre-cooled Tris buffer solution of polydopamine in step 1), stir evenly to obtain a clear solution, and let stand at room temperature until a gel is formed.

[0094] Comparative Example 3

[0095] A gelatin-chitosan hydrogel, the preparation method of which comprises the following steps:

[0096] 1) Take 1.0 ml of gelatin and add it to 15 mL of PBS buffer (pH 7.4), stir for 24 h to obtain gelatin phosphate buffer;

[0097] 2) Weigh 0.16 g of chitosan (deacetylation is 80-95%), add it to 60 mL of PBS buffer (pH 7.4), stir evenly, then take 5 mL and add it to the PBS buffer of gelatin in step 1), stir evenly, and let it stand until a gel is formed.

[0098] Comparative Example 4

[0099] An antibacterial hydrogel is prepared by the same method as in Example 1, except that, in step 5), the mixed solution B is transferred to a mold, polymerized at 0° C. for 6 hours, and then thawed to obtain the antibacterial hydrogel.

[0100] Comparative Example 5

[0101] An antibacterial hydrogel is prepared by the same method as in Example 1, except that, in step 5), the mixed solution B is transferred to a mold, polymerized at 0° C. for 6 h, then polymerized at -5° C. for 8 h, and then thawed to obtain the hydrogel.

[0102] Comparative Example 6

[0103] An antibacterial hydrogel is prepared by the same method as in Example 1, except that, in step 5), the mixed solution B is transferred to a mold, polymerized at -10°C for 24 hours, and then thawed to obtain the antibacterial hydrogel.

[0104] Comparative Example 7

[0105] An antibacterial hydrogel is prepared by the same method as in Example 2, except that, in step 5), the mixed solution B is transferred to a mold, polymerized at -5°C for 8 hours, and then thawed to obtain the antibacterial hydrogel.

[0106] Comparative Example 8

[0107] An antibacterial hydrogel, the preparation method of which is the same as that of Example 2, except that, in step 5), the mixed solution B is transferred to a mold, polymerized at -5°C for 8 hours, and then polymerized at -10°C for 12 hours, and the hydrogel is obtained after thawing.

[0108] Comparative Example 9

[0109] An antibacterial hydrogel, the preparation method of which is the same as that of Example 2, except that in step 5), the mixed solution B is transferred to a mold, polymerized at -15°C for 36 hours, and then thawed to obtain the antibacterial hydrogel.

[0110] Comparative Example 10

[0111] An antibacterial hydrogel and a preparation method thereof, comprising the following steps:

[0112] 1) 10 mmol of tris(hydroxymethyl)aminomethane was taken to prepare 30 mL of Tris buffer with a pH value of 8.5, and then 1.5 g of dopamine hydrochloride solid was added to the obtained Tris buffer, and stirred at room temperature for 48 h to obtain a Tris buffer of polydopamine;

[0113] 2) Take 0.75 g of gelatin, add it to 15 mL of PBS buffer (pH 7.4), and stir for 24 h to obtain gelatin PBS buffer;

[0114] 3) Weigh 0.12 g of chitosan (deacetylation is 80-95%), 2.25 g of EDC and 1.35 g of NHS, add them into 60 mL of PBS buffer (pH 7.4) respectively and stir evenly to obtain three solutions; mix the Tris buffer of polydopamine obtained in step 1) and the PBS buffer of gelatin obtained in step 2) with the three solutions obtained in this step and stir them in an ice bath until uniform, then transfer them to a mold, polymerize at 0°C for 6 h, then at -5°C for 8 h, and finally at -10°C for 10 h, and obtain the antibacterial hydrogel after thawing.

[0115] Test Example 1

[0116] The antibacterial zone test was carried out according to the standards set by the Clinical and Laboratory Standards Institute (CLSI) of the United States, and the antibacterial properties of the hydrogels prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were tested respectively. The antibacterial zone test specifically includes the following steps: sterilizing by ultraviolet irradiation for 30 minutes on a clean bench, and then dropping 100 μL of Escherichia coli and Staphylococcus aureus suspensions (1×10 8 CFU / mL) onto solid LB medium and spread it evenly with a spreading rod. Then, 0.3 g of hydrogel material (8 mm in diameter) was attached to the medium. After 15 min, the medium was returned to the 37°C biochemical incubator for inverted culture. After 24 h of culture, the medium was taken out to observe the bacterial growth on the medium and the diameter of the inhibition zone (D) was recorded. The results are shown in Table 1.

[0117] Table 1:

[0118]

[0119] Conclusion: It can be seen from Table 1 that the antibacterial activity of the antibacterial hydrogel prepared in the experimental example is significantly better than that of the hydrogel in the comparative example, and the gelatin hydrogel in comparative example 1 has no antibacterial activity, and the antibacterial activity of the gelatin-polydopamine hydrogel in comparative example 3 is slightly higher than that of the gelatin-chitosan hydrogel in comparative example 2, and the diameters of their inhibition zones are all between 3 and 5.5 mm. The antibacterial zone diameter of the antibacterial hydrogel obtained by cross-linking gelatin, chitosan and polydopamine in the experimental example is 11 to 13 mm. The results show that gelatin, chitosan and polydopamine can synergistically inhibit bacteria after cross-linking with each other.

[0120] Test Example 2

[0121] The biocompatibility of the antibacterial hydrogels prepared in Experimental Examples 1 and 2 was tested, and the testing method included the following steps:

[0122] 100uL mouse fibroblast L929 (1×10 4 / mL) of culture medium was inoculated in a 96-well plate. After the cells attached to the well plate, the antibacterial hydrogels (5 mm in diameter) prepared in Example 1 and Example 2 were transferred to the 96-well plate respectively, and the culture medium without hydrogel was used as the blank control group, and the culture medium was replaced every two days. After the cells were cultured for 3 days, the hydrogel was removed and the cells were washed twice with PBS. After that, 50uL of CCK8 solution was added to each well, and a negative control (blank culture medium) was set, and cultured in a cell culture incubator for 1 to 2 hours. Finally, the absorbance value (OD value) was detected at a wavelength of 450nm under an enzyme marker, and the cell survival rate was recorded and calculated (the results are shown in Figure 3 shown).

[0123] Conclusion: Figure 3 It can be seen that the cell survival rate of mouse fibroblasts cultured with the antibacterial hydrogel prepared in Example 1 can reach 94% to 98%, and the cell survival rate of mouse fibroblasts cultured with the antibacterial hydrogel prepared in Example 2 can reach 91% to 96%. The above results all show that the antibacterial hydrogels prepared in the examples have good biocompatibility.

[0124] Test Example 3

[0125] The elastic modulus of the antibacterial hydrogels of Experimental Examples 1 to 2 and Comparative Examples 4 to 10 was tested, and the testing method included the following steps:

[0126] Tensile tests were performed on different antibacterial hydrogel samples using a universal tensile testing machine at room temperature. Each hydrogel was cut into dumbbell-shaped samples with a width of 4 mm, a thickness of 3 mm, and a gauge length of 30 mm. The experimental tensile speed was set to 100 mm / min. Each antibacterial hydrogel was tested three times, and the average value was taken. The elastic modulus of the antibacterial hydrogel sample was obtained through the stress-strain curve. The specific results are shown in Table 2.

[0127] Table 2:

[0128] sample Elastic modulus (kpa) Example 1 87.0 Example 2 92.4 Comparative Example 4 20.2 Comparative Example 5 50.9 Comparative Example 6 72.3 Comparative Example 7 25.4 Comparative Example 8 57.8 Comparative Example 9 74.5 Comparative Example 10 54.7

[0129] Conclusion: As shown in Table 2, the elastic modulus of the antibacterial hydrogel obtained by three freezing stage polymerization in Example 1 and Example 2 is the highest, which is 87.0 and 92.4 kPa respectively; the freezing polymerization time of Comparative Example 6 and Comparative Example 9 is the same as that of Examples 1 and 2 respectively, but due to the conventional one-step freezing polymerization method adopted, the elastic modulus of the antibacterial hydrogel obtained is lower than that of Examples 1 and 2, and the freezing polymerization time of Comparative Example 6 and Comparative Example 9 is quite different, which is 24 hours and 36 hours respectively, but the elastic modulus of the antibacterial hydrogel finally obtained is not much different, indicating that the crosslinking process of the antibacterial hydrogels in the two comparative examples is The degree of crosslinking of the antibacterial hydrogels in Comparative Examples 4 and 7 is not much different; the freezing treatment time of Comparative Examples 4 and 7 is too short, and the crosslinking degree of the antibacterial hydrogel is too low, so their elastic modulus is the lowest; although Comparative Examples 5 and 6 adopt a staged freezing polymerization method, the total freezing time is insufficient, resulting in a low degree of crosslinking of the antibacterial hydrogel and a low elastic modulus; Comparative Example 10 adopts an antibacterial hydrogel prepared by a traditional one-step crosslinking method, and its elastic modulus is lower than that of the antibacterial hydrogel in the embodiment. It can be seen that the preparation method of the embodiment of the present invention can effectively improve the crosslinking uniformity of the hydrogel by controlling the pre-crosslinking degree of polydopamine and gelatin and then uniformly crosslinking with chitosan, thereby improving its mechanical properties.

[0130] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial hydrogel, characterized in that: The antibacterial hydrogel comprises an interpenetrating network structure of at least three polymer networks; the interpenetrating network structure comprises: The first network formed by cross-linking of polydopamine and gelatin; The second network formed by cross-linking polydopamine and chitosan; The third network formed by cross-linking chitosan and gelatin; Wherein, the first network, the second network and the third network are entangled with each other; The raw materials of the antibacterial hydrogel include: dopamine hydrochloride, gelatin and chitosan; the mass ratio of dopamine hydrochloride, gelatin and chitosan is 15-25:5-10:1-3; The preparation method comprises the following steps: dissolving dopamine hydrochloride in an alkaline buffer solution to perform self-polymerization to prepare a polydopamine solution; Mix the pre-cooled polydopamine solution and gelatin solution in an ice bath for 3 to 10 minutes; Under ice bath condition, chitosan solution and catalyst solution were added in sequence; The method comprises freezing treatment and thawing treatment to obtain the product; Wherein, the freezing process includes: First freezing: Freeze at 0~-5℃ for 6~8h; Secondary freezing: Freeze at -5 to -10°C for 8 to 12 hours; Three-stage freezing: Freeze at -10 to -15°C for 10 to 16 hours.

2. The preparation method according to claim 1, characterized in that: The concentration of the polydopamine solution is 1-10 wt %.

3. The preparation method according to claim 1, characterized in that: The concentration of the gelatin solution is 0.5-5wt%.

4. The preparation method according to claim 1, characterized in that: The concentration of the chitosan solution is 0.15-1.5 wt %.

5. The preparation method according to claim 1, characterized in that: The catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide.

6. The preparation method according to claim 1, characterized in that: The concentration of 1-ethyl-(3-dimethylaminopropyl)carbodiimide in the catalyst solution is 0.75-7.5 wt %, and the concentration of N-hydroxysuccinimide is 0.45-4.5 wt %.

7. The preparation method according to claim 1, characterized in that: The alkaline buffer is a Tris buffer with a pH value of 8.5 to 9; The solvent of the gelatin solution, chitosan solution or catalyst solution is selected from one of PBS buffer, MOPS buffer and HEPES buffer; The solvent of the gelatin solution or chitosan solution or catalyst solution is PBS buffer solution with a pH value of 7-8.

8. An antibacterial hydrogel prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the antibacterial hydrogel according to claim 8 in preparing biological scaffolds, cell culture materials, drug controlled release materials or tissue engineering materials.

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