Method for preparing oriented porous hydrogel by using crystalline salt template

Abstract

The invention provides a method for preparing oriented porous hydrogel by using a salt crystallization template, which comprises the following steps of: mixing salt and hydrogel monomers, cooling to obtain a supersaturated salt hydrogel solution, placing a crystal nucleus template in the solution to guide nucleation and growth of salt crystals, and finally curing and cleaning the hydrogel to obtain the oriented porous hydrogel. The prepared hydrogel is anisotropic, highly ordered, controllable in pore structure size and high in biocompatibility. The preparation method has the characteristics of simple equipment, low cost, simplicity, convenience and easiness in operation, and the hydrogel can be selected from a wide variety of preparation materials and has a wide application prospect in the field of tissue engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of tissue engineering and biomanufacturing under biomedical engineering, and specifically relates to a method for preparing directional porous hydrogel by using a crystal salt template. Background Art

[0002] Hydrogels are composed of a three-dimensional network of hydrophilic polymers, which swell but do not dissolve in water. Because of their structural composition and moist and soft texture similar to the extracellular matrix, hydrogels are widely used in drug delivery, biomedical engineering, and tissue engineering. However, due to the limitation of the diffusion distance of substances (usually limited to 200 microns), it is difficult for cells to exchange substances inside the hydrogel block, such as the acquisition of nutrients and the timely discharge of metabolic waste. This makes the application of hydrogel blocks in tissue engineering subject to certain restrictions. Porous hydrogels, especially directional porous structures, can enhance the fluid transport capacity inside the hydrogel, making it easier to transport nutrients, oxygen and metabolic waste in the gel, thereby supporting the culture of larger volumes of cell tissues.

[0003] At present, most methods for preparing directional porous hydrogels use directional freezing method, which applies unidirectional or multidirectional temperature gradient to hydrogel aqueous solution to make ice crystals grow in a directional manner, and finally removes ice crystals through a series of post-processing methods to obtain hydrogels with directional channels. Although this method has wide applicability, it requires extremely low temperature (-90℃ to -196℃) to provide the required temperature gradient, and can only prepare simple unidirectional directional hydrogels, which has the disadvantages of high energy consumption, long preparation cycle and small sample size.

[0004] Therefore, it is necessary to design a method to prepare oriented porous hydrogels by crystallization at room temperature. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for preparing oriented porous hydrogel using a crystal salt template, which has the characteristics of simple equipment, low cost, simple and easy operation, and a wide range of selectable hydrogel monomers and strong versatility. The method can realize the preparation of anisotropic, highly ordered, highly biocompatible, and pore structure size controllable oriented porous hydrogel.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:

[0007] A method for preparing directional porous hydrogel using a crystal salt template, comprising mixing salt and a hydrogel monomer into a salt-containing hydrogel precursor solution, cooling the salt-containing hydrogel precursor solution to reach supersaturation, placing a crystal nucleus template in the supersaturated solution to guide the nucleation and directional growth of salt crystals, and finally preparing a hydrogel with directional porosity by crosslinking and washing the hydrogel.

[0008] Specifically:

[0009] A method for preparing an oriented porous hydrogel using a crystal salt template comprises the following steps:

[0010] (1) mixing a hydrogel monomer, a photoinitiator and water to prepare a hydrogel solution; dissolving salt in water to prepare a salt solution; and mixing the hydrogel solution and the salt solution to prepare a salt-containing hydrogel precursor solution;

[0011] (2) cooling the salt-containing hydrogel precursor solution to below the crystallization temperature of the salt, so that the salt-containing hydrogel precursor solution is in a supersaturated state, and then placing a crystal nucleus template to allow it to completely crystallize;

[0012] (3) subjecting the completely crystallized salt-containing hydrogel precursor solution to light cross-linking, and then washing the solidified hydrogel with deionized water to remove the salt crystals, thereby obtaining the oriented porous hydrogel.

[0013] In the above step (1):

[0014] The water used to prepare the hydrogel solution is preferably deionized water; the water used to prepare the salt solution is preferably purified water.

[0015] Preferably, the hydrogel monomer is one or more of acrylamide, acrylic acid, n-isopropyl acrylamide, polyether F127 diacrylate, polyethylene glycol, methacrylated gelatin, methacrylated hyaluronic acid, methacrylated chitosan, and methacrylated silk fibroin. More preferably, acrylamide is used.

[0016] As further preferred, when the hydrogel monomer is one or more of acrylamide, acrylic acid, n-isopropylacrylamide, polyether F127 diacrylate, and polyethylene glycol, a crosslinking agent is simultaneously added to the hydrogel solution.

[0017] As further preferred, the crosslinking agent is selected from one or both of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate. The crosslinking agent is preferably N,N'-methylenebisacrylamide.

[0018] As a further preferred ratio, the mass ratio of the hydrogel monomer to the crosslinking agent is (15-150): 1. More preferably, it is (20-40): 1. The mass ratio of the hydrogel monomer to the crosslinking agent is preferably 30:1.

[0019] Preferably, the photoinitiator is phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt.

[0020] Preferably, the mass ratio of the hydrogel monomer to the photoinitiator is (1-200):1.

[0021] As further preferred, when the hydrogel monomer is one or more of acrylamide, acrylic acid, n-isopropyl acrylamide, polyether F127 diacrylate, polyethylene glycol, the mass ratio of the hydrogel monomer to the photoinitiator is (100-150):1, and more preferably 120:1.

[0022] As further preferred, when the hydrogel monomer is selected from one or more of methacrylated gelatin, methacrylated hyaluronic acid, methacrylated chitosan, and methacrylated silk fibroin, the mass ratio of the hydrogel monomer to the photoinitiator is (3-10):1, and more preferably 8:1.

[0023] Preferably, in the hydrogel solution, the mass ratio of hydrogel monomer to water is (0.1-1.5):1.

[0024] As further preferred, when the hydrogel monomer is selected from one or more of acrylamide, acrylic acid, n-isopropylacrylamide, polyether F127 diacrylate, and polyethylene glycol, the mass ratio of the hydrogel monomer to water in the hydrogel solution is (0.8-1.2):1. More preferably, it is 1:1.

[0025] As further preferred, when the hydrogel monomer is selected from one or more of methacrylated gelatin, methacrylated hyaluronic acid, methacrylated chitosan, and methacrylated silk fibroin, the mass ratio of the hydrogel monomer to water in the hydrogel solution is (0.1-0.5):1. More preferably, it is 0.2:1.

[0026] Preferably, the salt is sodium acetate or a mixture of sodium acetate and one or more of carbonamide, sodium thiosulfate, sodium nitrate, sodium sulfate, potassium nitrate, sodium phosphate, and ammonium sulfate. More preferably, it is a mixture of sodium acetate or sodium acetate and carbonamide. Among them, sodium acetate is anhydrous sodium acetate. The above salts can form supersaturated solutions at 25°C, so the preparation of oriented porous hydrogels at room temperature can be achieved.

[0027] Preferably, in the salt solution, the mass ratio of sodium acetate to water is (0.5-1.7):1. More preferably, it is (0.8-1.3):1. More preferably, it is (1-1.1):1.

[0028] As further preferred, when the salt is a mixture of sodium acetate and carbonamide, the mass ratio of sodium acetate to carbonamide is (2-4):1.

[0029] Preferably, in the hydrogel precursor solution containing salt water, the volume ratio of the hydrogel solution to the salt solution is 1:35 to 10:1, more preferably 1:(1 to 8), and even more preferably 1:(2 to 4).

[0030] In the above step (2):

[0031] The supersaturated state refers to the concentration of salt dissolved in the solution being higher than the saturated solubility at that temperature, and the solution presents an unstable state. When the supersaturated solution is disturbed or a small amount of crystal nuclei are added, the solute (salt) will crystallize out of the solution. According to this principle, the nucleation and growth of salt crystals can be controlled by controlling the spatial distribution of the crystal nuclei (i.e., the support structure of the crystal nucleus template). The crystal nucleus template is placed in a supersaturated solution, and the salt crystals will first nucleate twice near the crystal nuclei. The salt crystals nucleate and grow according to the spatial distribution of the seed crystals (crystal nuclei) (the salt crystals grow vertically to the structure of the crystal nucleus template) until crystallization is completed.

[0032] Preferably, the temperature of the hydrogel precursor solution is lowered to 50 to -40°C, more preferably to 8 to 25°C, and even more preferably to 8°C.

[0033] Preferably, the crystal core template is prepared by the following method:

[0034] The scaffold is prepared by using fused deposition modeling or light-curing 3D printing, and then the crystal core is evenly applied on the scaffold to obtain a crystal core template.

[0035] The crystal nucleus (crystal seed) is a substance that can trigger the crystallization of a supersaturated salt solution.

[0036] As further preferred, the crystal nucleus is one or more of sodium acetate trihydrate powder, sodium acetate powder, sodium thiosulfate powder, sodium nitrate powder, sodium sulfate powder, potassium nitrate powder, sodium phosphate powder, and ammonium sulfate powder. Even more preferably, it is sodium acetate trihydrate powder.

[0037] Preferably, the support material can be selected from polymer materials, metal materials, ceramic materials, etc. More preferably, the support material is a polymer material. More preferably, the support material is polylactic acid or a light-curable resin material.

[0038] The material used for fused deposition modeling is preferably photocurable resin; the material used for photocurable 3D printing is preferably polylactic acid.

[0039] The template (scaffold) prepared by fused deposition modeling and photo-stereolithography 3D printing has natural layer textures, and the gaps in the layer textures can effectively adhere to the above-mentioned crystal seeds (nuclei).

[0040] Preferably, the structure of the support can be a combination of one or more of a one-dimensional single point, a row of dot matrix, a two-dimensional dot matrix, a straight line, a curve, a polygonal frame, a curve frame, and a three-dimensional solid model.

[0041] The complete crystallization in this step refers to waiting for 5 minutes after the surface of the salt-containing hydrogel precursor solution is completely covered with crystals to allow it to fully crystallize.

[0042] In the above step (3):

[0043] Preferably, the illumination wavelength is 380-500 nm, and the illumination time is 3-10 min. More preferably, the illumination wavelength is 405 nm, and the illumination time is 5 min.

[0044] Preferably, the specific process of washing with deionized water to remove salt crystals is as follows:

[0045] Soak the solidified hydrogel in water for 30 minutes and take it out; repeat the operation three times.

[0046] The photo-crosslinking of the completely crystallized salt-containing water gel precursor solution can be carried out by irradiating the entire salt-containing water gel precursor solution to achieve full curing at one time; or curing can be carried out in batches through a photomask.

[0047] The use of photomasks can achieve the diversity of hydrogel porous structures and enrich the internal porous structure of directional porous hydrogels by using crystal core templates of different structural supports or different placement angles of crystal core templates of the same structural support during each curing. The specific process of curing in batches through photomasks is as follows:

[0048] S10, adding lemon yellow powder to the salt-containing hydrogel precursor solution prepared in the above step (1), and using it as a precursor solution for subsequent operations;

[0049] S20, obtaining a completely crystallized precursor solution according to step (2), placing a photomask on the crystallized precursor solution (the area of ​​the photomask is smaller than the surface area of ​​the precursor solution), and irradiating with light for partial cross-linking;

[0050] S30, heating the partially cross-linked precursor solution to melt the uncross-linked precursor solution back into a solution state;

[0051] S40, then repeating steps S20 and S30 for the partially cross-linked precursor solution, and repeating the cycle until all the salt-containing hydrogel precursor solutions are completely cross-linked and solidified.

[0052] Among them, in step S40, when the operation in step S20 is repeated on the salt-containing hydrogel precursor solution, a crystal nucleus template with the same structure as in the previous cycle can be used to change the channel direction by adjusting the placement angle of the crystal nucleus template or using a crystal nucleus template with a different structure from that in the previous cycle.

[0053] Preferably, the volume ratio of the added mass of the lemon yellow powder to the salt-containing hydrogel precursor solution is (0.5-5) mg / mL, and more preferably (0.5-2) mg / mL.

[0054] The method for preparing directional porous hydrogel using salt crystal template of the present invention comprises mixing salt with hydrogel monomer, cooling to form a supersaturated salt water gel solution, placing a crystal nucleus template in the solution to guide the nucleation and growth of salt crystals, and finally preparing anisotropic, highly ordered, controllable pore structure size and highly biocompatible hydrogel by means of hydrogel solidification and washing. The preparation method has the characteristics of simple equipment, low cost, simple and easy operation, and a wide range of materials can be selected for preparation of hydrogel, and has broad application prospects in the field of tissue engineering.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The method for preparing oriented porous hydrogel using a crystallized salt template of the present invention comprises the following steps: adding a salt solution into a hydrogel solution to prepare a salt-containing hydrogel precursor solution, cooling the solution to below the crystallization temperature of the salt to form a supersaturated solution, placing a crystal nucleus template to trigger crystallization, and finally performing photo-crosslinking to solidify the solution. The salt crystals are washed off with water to obtain the corresponding oriented porous hydrogel.

[0057] (1) The preparation method of the present invention is a supplement to the existing preparation method of oriented hydrogel, expands the existing preparation method of oriented hydrogel, and has the characteristics of simple equipment, low cost, and simple and easy operation.

[0058] (2) The preparation method of the present invention can prepare oriented porous hydrogel by crystallization at room temperature, and the crystallization process can be continuously conducted without continuous energy input, which has the characteristics of energy saving and green environmental protection.

[0059] (3) The preparation method of the present invention has the advantage of fast crystallization speed, which is as high as 1.335 mm / s, saving time and cost and shortening the manufacturing cycle. More importantly, there is no sample size limit, and large-sized samples can be prepared.

[0060] (4) The preparation method of the present invention can guide the nucleation and growth of salt crystals by 3D printing a personalized customized template (scaffold), thereby preparing a directional hydrogel with multiple pore orientations. In addition, by 3D printing a three-dimensional template, a three-dimensional directional pore hydrogel can also be prepared, which has never been reported.

[0061] (5) The salt (crystals) used in the preparation method of the present invention can be completely removed by washing with deionized water without any residue, and the obtained hydrogel has high biocompatibility.

[0062] (6) The preparation method of the present invention has a wide range of material selection and strong versatility. The hydrogel prepared by the preparation method of the present invention has the advantages of anisotropy, high order, and controllable pore structure size. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0064] Figure 1 This is a schematic diagram of the porous hydrogel preparation process of Example 1;

[0065] Figure 2 In the figure, a is the linear crystal nucleus template prepared in Example 1 and the triangular crystal nucleus template and the quadrilateral crystal nucleus template prepared in Example 2; b is the two-dimensional lattice crystal nucleus template prepared in Example 2;

[0066] Figure 3 In the figure, a is an optical microscope picture of the salt-containing hydrogel precursor solution prepared in Example 1 after crystallization; b is a real picture of the hydrogel prepared by the linear crystal core template prepared in Example 1 after the salt crystals are washed away; c is a scanning electron microscope picture of the internal microstructure of the hydrogel prepared by the linear crystal core template prepared in Example 1, in which the pore orientation can be clearly seen.

[0067] Figure 4 The three hydrogels prepared in Example 2 are photos of the real objects; a is a hydrogel prepared by a triangular crystal core template; b is a hydrogel prepared by a quadrilateral crystal core template; c is a hydrogel prepared by a two-dimensional lattice crystal core template;

[0068] Figure 5 In the figure, a is a scanning electron micrograph of the internal microstructure of the hydrogel prepared by the triangular crystal core template in Example 2; b is a scanning electron micrograph of the internal microstructure of the hydrogel prepared by the quadrilateral crystal core template in Example 2; the pore orientation can be clearly seen; c is a scanning electron micrograph of the internal microstructure of the hydrogel prepared by the two-dimensional lattice crystal core template in Example 2; the multiple orientations of the pores can be clearly seen.

[0069] Figure 6In the figure, a is a schematic diagram of the process of preparing the oriented porous hydrogel by the photomask method in Example 3; b is an optical microscope picture of the oriented porous hydrogel prepared by the photomask method in Example 3. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0071] Specific implementation The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0072] In the following examples, polylactic acid was purchased from Shenzhen Tuozhu Technology Co., Ltd., and the product model is PLA-BASIC.

[0073] Embodiment 1:

[0074] like Figure 1 As shown, a method for preparing an oriented porous hydrogel using a crystallized salt template comprises the following steps:

[0075] (1) First, prepare a hydrogel solution: use an electronic balance to weigh 6 g of acrylamide, 0.2 g of N,N'-methylenebispropionamide, and 0.05 g of phenyl (2,4,6-trimethylbenzoyl) lithium phosphate, respectively, and put them into 6 mL of deionized water, and mix them by magnetic stirring to form a clear and transparent hydrogel solution; the hydrogel solution is subjected to a light-shielding treatment, and the purpose of the light-shielding treatment is to prevent external light from interfering with the solution.

[0076] (2) Preparation of salt solution: 22 g of anhydrous sodium acetate was weighed using an electronic balance, added to 20 mL of pure water, and mixed, and then heated in a water bath for one hour to completely dissolve the mixture into a clear and transparent solution, thereby obtaining a salt solution.

[0077] (3) The hydrogel solution and the salt solution are uniformly mixed to obtain a salt-containing hydrogel precursor solution, and the solution is stored in a dark place at 80° C. to prevent interference of external light on the solution.

[0078] (4) Using polylactic acid as the printing material, the following Figure 2 In the linear stent shown in a, sodium acetate trihydrate powdered crystal nuclei are evenly applied on the surface of the linear stent to prepare a linear crystal nucleus template.

[0079] (5) Use a pipette to take 1 mL of the salt-containing hydrogel precursor solution prepared in step (3) and place it in a clean culture dish, and gently shake it to make the thickness of the solution uniform. Then cool the culture dish in a refrigerator at 8° C. for 20 minutes to obtain a supersaturated precursor solution.

[0080] Then, the linear crystal core template was placed in the supersaturated precursor solution to trigger crystallization. After the upper surface of the solution in the culture dish was transformed into crystals, it was placed in the refrigerator for 5 minutes to allow it to fully crystallize. During this process, the crystallization process was recorded with a camera, and the time taken for crystallization was recorded. The crystallization distance was divided by the crystallization time to obtain the crystallization speed; the crystallization speed was 1.335 mm / s.

[0081] In the case of a linear core template, an optical micrograph of a fully crystallized supersaturated precursor solution is shown in FIG. Figure 3 As shown in a; Figure 3 As can be seen in a, the salt crystals in the supersaturated precursor solution after crystallization are straight and grow in parallel directions.

[0082] The completely crystallized supersaturated precursor solution was then irradiated with blue light (405 nm) for 5 min to crosslink and solidify the hydrogel therein.

[0083] (6) Soaking the cross-linked and cured hydrogel in deionized water for 30 minutes and then taking it out; repeating this process three times, dissolving the salt in the hydrogel with deionized water to obtain an oriented porous hydrogel.

[0084] The actual picture of the hydrogel prepared by the linear crystal core template is as follows: Figure 3 As shown in b. Figure 3 c is a scanning electron micrograph of the internal microstructure of the hydrogel prepared by the linear crystal core template; Figure 3 As can be clearly seen in middle c, the hydrogel has horizontally oriented pores.

[0085] Embodiment 2:

[0086] First, according to step (4) in Example 1, a triangular bracket and a quadrilateral bracket (such as Figure 2 a) and two-dimensional lattice scaffolds (as shown in Figure 2 (as shown in b).

[0087] The oriented porous hydrogel is prepared according to the preparation process in Example 1, except that: in step (4), a triangular scaffold, a quadrilateral scaffold and a two-dimensional lattice scaffold are used to prepare a crystal core template, which is used in subsequent steps (5) and (6), and finally an oriented porous hydrogel corresponding to the triangular crystal core template, the quadrilateral crystal core template and the two-dimensional lattice crystal core template is obtained.

[0088] The actual pictures of the three hydrogels obtained above are as follows Figure 4 As shown, Figure 4 In the figure, a, b, and c are hydrogels prepared by triangular core template, quadrilateral core template, and two-dimensional lattice core template, respectively.

[0089] Figure 5 a and b are scanning electron microscope images of the internal microstructure of the hydrogels prepared by the triangular crystal core template and the quadrilateral crystal core template, respectively; Figure 5 As can be seen from a and b, the polygonal core template can obtain oriented porous hydrogels with multiple pore directions. Figure 5 Figure c is a scanning electron microscope image of the internal microstructure of the hydrogel prepared by the two-dimensional lattice core template, in which the multiple orientations of the pores can be clearly seen. Figure 5 It can be seen that there are pores ranging from tens to hundreds of microns inside the hydrogel, and the relative angles between the pores are controlled by the geometric structure of the crystal core template (the pores are perpendicular to the geometric structure of the crystal core template).

[0090] Embodiment 3:

[0091] (1) Preparation of hydrogel solution: 0.4 g of methacryloyl gelatin freeze-dried sample and 0.05 g of phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt powder were weighed using an electronic balance and placed in 2 mL of deionized water. The mixture was allowed to stand in a 37° C. water bath for one hour to obtain a uniform, clear and transparent hydrogel solution.

[0092] (2) Preparation of salt solution: 4 g of anhydrous sodium acetate and 1.6 g of carbon amide were weighed using an electronic balance, and then added to 4 mL of pure water and mixed. The mixture was heated in a water bath for one hour to completely dissolve the mixture into a clear and transparent solution, thereby obtaining a salt solution.

[0093] (3) The hydrogel solution and the salt solution are uniformly mixed to obtain a salt-containing hydrogel precursor solution, and the solution is stored in a light-shielded state at 60° C. The purpose of the light-shielding treatment is to prevent the solution from being disturbed by external light.

[0094] (4) According to steps (4) to (6) in Example 1, a directional porous methacrylated gelatin hydrogel scaffold with high biocompatibility was prepared.

[0095] Embodiment 4:

[0096] (1) According to steps (1)-(4) in Example 1, a salt-containing hydrogel precursor solution and a linear crystal core template were prepared respectively, and lemon yellow powder (the volume ratio of the added mass to the salt-containing hydrogel precursor solution was 1 mg / mL) was added thereto, and a light yellow clear solution (precursor solution) was obtained after uniform mixing. Among them, lemon yellow, as a light absorber, can prevent blue light scattering during the photocuring process and improve the photocuring accuracy.

[0097] (2) Use a pipette to take 1 mL of the light yellow clear solution and place it in a clean Petri dish. Gently shake the solution to make it uniform in thickness. Then place the Petri dish in a refrigerator at 8°C for 20 minutes to obtain a supersaturated precursor solution.

[0098] The linear crystal core template is then placed horizontally into the supersaturated precursor solution to trigger crystallization. After the upper surface of the solution in the culture dish is transformed into a crystal, it is placed in a refrigerator for 5 minutes to allow it to fully crystallize.

[0099] (3) Figure 6 As shown in a, a rectangular photomask is used to selectively crosslink and cure (405 nm irradiation for 5 min) one of the areas. After the first photocuring crosslinking, the culture dish is heated to melt the area that has not been cured by light irradiation back into a solution.

[0100] The partially solidified solution is then cooled to 8°C again, the angle of the linear crystal core template is switched to 45° with the horizontal line, and a certain area is selectively solidified using a photomask to complete the second solidification.

[0101] according to Figure 6 As shown in a, the placement angle of the linear core template is adjusted and this step is repeated until the entire hydrogel is completely solidified.

[0102] (4) The fully cured hydrogel is treated according to step (6) in Example 1 to finally obtain a porous hydrogel with anisotropic pores.

[0103] The optical micrograph of the porous hydrogel prepared in this embodiment is shown in the attached figure. Figure 6 As shown in b, horizontal channels are obtained in the hydrogel for the first time, and channels with an angle of 45° are obtained by the second solidification.

[0104] The above experimental results show that the pore structure and relative pore angle of the porous hydrogel prepared in this embodiment can be precisely controlled by placing the linear crystal core template.

[0105] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0106] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. 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 application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing oriented porous hydrogel using a crystal salt template, characterized in that: The following steps are involved: (1) mixing a hydrogel monomer, a photoinitiator and water to prepare a hydrogel solution; dissolving salt in water to prepare a salt solution; and mixing the hydrogel solution and the salt solution to prepare a salt-containing hydrogel precursor solution; (2) cooling the salt-containing hydrogel precursor solution to below the crystallization temperature of the salt, so that the salt-containing hydrogel precursor solution is in a supersaturated state, and then placing a crystal nucleus template to allow it to completely crystallize; (3) subjecting the completely crystallized salt-containing hydrogel precursor solution to light cross-linking, and then washing the solidified hydrogel with deionized water to remove the salt crystals, thereby obtaining the oriented porous hydrogel.

2. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The hydrogel monomer is one or more of acrylamide, acrylic acid, n-isopropyl acrylamide, polyether F127 diacrylate, polyethylene glycol, methacrylylated gelatin, methacrylylated hyaluronic acid, methacrylylated chitosan, and methacrylylated silk fibroin; Wherein, when the hydrogel monomer is one or more of acrylamide, acrylic acid, n-isopropyl acrylamide, polyether F127 diacrylate, and polyethylene glycol, a crosslinking agent is simultaneously added to the hydrogel solution; The cross-linking agent is selected from one or both of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate.

3. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The photoinitiator is phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt.

4. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: In the hydrogel solution, the mass ratio of hydrogel monomer to water is (0.1-1.5):

1.

5. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The salt is sodium acetate or a mixture of sodium acetate and one or more of carbonamide, sodium thiosulfate, sodium nitrate, sodium sulfate, potassium nitrate, sodium phosphate, and ammonium sulfate.

6. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 5, characterized in that: In the salt solution, the mass ratio of sodium acetate to water is (0.5-1.7):

1.

7. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: In the hydrogel precursor solution containing salt water, the volume ratio of the hydrogel solution to the salt solution is 1:35 to 10:

1.

8. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The crystal core template is prepared by the following method: The scaffold is prepared by using a fused deposition modeling or a light-curing 3D printing method, and then the crystal core is evenly applied on the scaffold to obtain a crystal core template; Wherein, the crystal nucleus is one or more of sodium acetate trihydrate powder, sodium acetate powder, sodium thiosulfate powder, sodium nitrate powder, sodium sulfate powder, potassium nitrate powder, sodium phosphate powder, and ammonium sulfate powder.

9. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The illumination wavelength is 380-500nm, and the illumination time is 3-10min.

10. The method for preparing oriented porous hydrogel using a crystal salt template according to claim 1, characterized in that: The specific process of washing with deionized water to remove salt crystals is as follows: Soak the solidified hydrogel in water for 30 minutes and take it out; repeat the operation three times.

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