阅读说明：本技术 一种高回弹丝素蛋白气凝胶 (High-resilience silk fibroin aerogel ) 是由 卢神州 温壮壮 吴峰 姜福建 于 2019-01-31 设计创作，主要内容包括：本发明公开了一种高回弹丝素蛋白气凝胶,通过如下步骤制备得到：将丝素蛋白水溶液和糖类小分子物质的水溶液混合得到混合溶液,将所述混合溶液进行剪切后冷冻干燥,得到所述高回弹丝素蛋白气凝胶。本发明中制备得到的丝素蛋白气凝胶具有三维气泡结构,内部含有大量封闭空气,不与外界连通,在压缩率为50％时的压缩回弹率高达50％～75％。此外,该气凝胶还具有低密度、高孔隙率、良好的生物相容性以及可降解性等特点,可用于医用敷料、组织修复等方面,可以为细胞生长、粘附和增殖提供良好的生物环境,该气凝胶也可用作组织培养支架。(The invention discloses a high-resilience silk fibroin aerogel which is prepared by the following steps: and mixing the silk fibroin aqueous solution and the aqueous solution of the sugar micromolecule substance to obtain a mixed solution, shearing the mixed solution, and freeze-drying to obtain the high-resilience silk fibroin aerogel. The silk fibroin aerogel prepared by the method has a three-dimensional bubble structure, contains a large amount of closed air inside, is not communicated with the outside, and has a compression rebound rate as high as 50-75% when the compression rate is 50%. In addition, the aerogel also has the characteristics of low density, high porosity, good biocompatibility, degradability and the like, can be used for medical dressing, tissue repair and the like, can provide a good biological environment for cell growth, adhesion and proliferation, and can also be used as a tissue culture scaffold.)

1. The high-resilience silk fibroin aerogel is characterized by being prepared by the following steps: and mixing the silk fibroin aqueous solution and the aqueous solution of the sugar micromolecule substance to obtain a mixed solution, shearing the mixed solution, and freeze-drying to obtain the high-resilience silk fibroin aerogel.

2. The high resilience silk fibroin aerogel according to claim 1, wherein the mass ratio of the sugar small molecules to the silk fibroin in the mixed solution is 1: 3-9.

3. The high resilience silk fibroin aerogel according to claim 2, wherein the mass ratio of the sugar-based small molecules to the silk fibroin in the mixed solution is 1:3.4, 1:4.5, 1:4.55, or 1: 8.4.

4. The high resilience silk fibroin aerogel according to claim 1, wherein the sugar-based small molecule substance is glucose, xylose or fructose.

5. The high resilience silk fibroin aerogel according to claim 1, wherein the high resilience silk fibroin aerogel has an apparent density of 0.02g/cm³～0.04g/cm³。

6. The high resilience silk fibroin aerogel according to claim 1, wherein the high resilience silk fibroin aerogel has a resilience against compression of 50% to 75% at a compression ratio of 50%.

7. The high resilience silk fibroin aerogel according to claim 1, wherein the strength of the high resilience silk fibroin aerogel is 45-55 kPa when the compressibility is 50%.

8. The high resilience silk fibroin aerogel according to claim 1, wherein the shearing speed during shearing is 500-1500 r/min, and the shearing time is 20-60 min.

9. The high resilience silk fibroin aerogel according to claim 1, wherein the container used in shearing is a hemispherical container or a bowl-shaped container.

10. The high resilience silk fibroin aerogel according to claim 1, wherein the stirrer used in shearing comprises at least one conical stirring rod with a lower dimension larger than an upper dimension.

Technical Field

The invention relates to the technical field of silk fibroin aerogel, and particularly relates to high-resilience silk fibroin aerogel with a three-dimensional bubble structure.

Background

Aerogel materials are a special type of gel that uses a gas to replace the liquid in the gel and has a stable three-dimensional network structure. The density of the aerogel is about 0.003 to 0.5g/cm³The density can be as low as 0.001g/cm³The smoke is the lightest solid material in the world at present and is called solid smoke. The nano-cavity structure in the aerogel endows the aerogel with the advantages of low thermal conductivity, low resistivity, low refractive index and the like, so that the aerogel has wide application prospects in the aspects of adsorption materials, heat insulation materials and high-performance capacitors.

Aerogels are generally classified into three types, inorganic aerogels, organic polymer aerogels and cellulose aerogels, according to the source of the raw material. Inorganic aerogel and organic polymer aerogel are always concerned, the preparation method is continuously updated, the used raw materials are continuously optimized, and the inorganic aerogel and the organic polymer aerogel are widely applied. However, the inorganic aerogel and the organic polymer aerogel are difficult to biodegrade, have poor biocompatibility and limit the application and popularization of the inorganic aerogel and the organic polymer aerogel. On the other hand, since the cellulose aerogel has the advantages of abundant resources, no toxicity and reproducibility, the continuous temperature rise is studied in recent years.

At present, the preparation method of the cellulose aerogel mainly comprises the following two steps: firstly, preparing hydrogel, and then replacing water in the gel by supercritical drying or freeze drying and the like to obtain the aerogel. However, the aerogel obtained by this method has problems of low strength and easy collapse, so there is a need to research a high-strength aerogel material.

The silk fibroin is natural high molecular fiber protein extracted from silk, accounts for 70-80% of the silk, and contains 18 amino acids. The fibroin has good mechanical properties and physicochemical properties, such as good biocompatibility and degradability, low immunogenicity, slow release and the like, and can be processed into different forms, such as fibers, solutions, powders, films and gels, so that the fibroin can be widely applied to the field of biomaterials.

The research on the silk fibroin aerogel is relatively few at present, for example, the invention patent of Chinese patent application No. 201610199399.X, named as "a composite natural polymer gel material", discloses that cyclodextrin/reactive polymer supramolecular inclusion compound is used as a cross-linking agent, so that gel forms partial chemical cross-linking, and high-strength aerogel is obtained through supercritical drying. For example, the aerogel prepared in the invention patent of chinese patent application No. 201610526187.8, entitled "a method for preparing silk fibroin aerogel", is easily broken and has poor resilience when compressed, and greatly limits the application range of the silk fibroin aerogel.

Disclosure of Invention

In view of the above, in order to overcome the defects of the prior art, the present invention aims to provide a high resilience silk fibroin aerogel.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of high-resilience silk fibroin aerogel takes silkworm cocoon shells as raw materials and comprises the following steps: adding sugar micromolecular substances into the silk fibroin aqueous solution, and uniformly mixing to prepare a mixed solution; and after the mixed solution is poured into a container, a stirrer is used for shearing the mixed solution at a high speed, the mixed solution is converted into a foam shape, and the foam-shaped mixed solution is poured into a mould for freeze drying to obtain the silk fibroin aerogel.

In some embodiments, the method specifically comprises the following steps:

(1) placing the silkworm cocoons into a slightly-boiling (100 ℃) sodium bicarbonate/sodium carbonate buffer solution with the temperature of 0.01MpH being 9.5 for keeping for 30min, taking out the cocoon silks, cleaning the cocoon silks by deionized water, repeating the above experiment for three times to remove sericin in the cocoon shells, dissolving the sericin by lithium bromide, dialyzing to obtain a pure silk fibroin protein solution, and diluting the pure silk fibroin protein solution into the silk fibroin protein aqueous solution by using the deionized water; the concentration of the silk fibroin aqueous solution is 30 mg/mL-60 mg/mL;

(2) preparing 100mg/mL aqueous solution of a sugar micromolecule substance, and adding the aqueous solution of the sugar micromolecule substance into the silk fibroin aqueous solution to prepare a mixed solution, wherein the concentration of the sugar micromolecule substance in the mixed solution is 4 mg/mL-15 mg/mL, and the concentration of silk fibroin in the mixed solution is 30 mg/mL-65 mg/mL;

(3) heating the mixed solution to 20-30 ℃, then pouring the mixed solution into a container, and shearing the mixed solution at a high speed by using a stirrer at the temperature of 20-30 ℃ to enable the mixed solution to form a large amount of bubbles in the container, so that the mixed solution is converted into a foam shape; in some embodiments, the stirring temperature is preferably 25 ℃;

(4) and pouring the foamed mixed solution into a mold for freeze drying to obtain the high-resilience silk fibroin aerogel.

According to some preferred aspects of the invention, the sugar small molecule substance is glucose, xylose or fructose.

According to some preferred aspects of the invention, the container is a hemispherical container or a bowl-like container.

According to some preferred aspects of the invention, the agitator comprises at least one conical agitator bar having a lower dimension greater than an upper dimension.

Preferably, the conical stirring rod comprises a rotating rod positioned in the middle and a plurality of stirring paddles connected to the rotating rod, and the outer edges of the plurality of stirring paddles are positioned on the same virtual conical surface. In some embodiments, the stirring paddle is in a form similar to a triangle, a plurality of stirring paddles in the shape of a triangle form a virtual conical surface, the side edges of the stirring paddle are positioned on the side surface of the virtual conical surface, the bottom edge of the stirring paddle is positioned on the bottom surface of the virtual conical surface, and the rotating rod is connected to the vertex of the conical surface.

According to some preferred aspects of the present invention, the high speed shearing in step (3) has a shearing speed of 500r/min to 1500r/min and a shearing time of 20min to 60 min.

According to some preferred aspects of the invention, the freeze-drying in step (4) is performed under conditions of freezing at-40 ℃ to-80 ℃ for 4 to 8 hours, gradually raising the temperature and performing vacuum drying.

The invention also provides the high-resilience silk fibroin aerogel prepared by the preparation method, and the apparent density of the high-resilience silk fibroin aerogel is 0.02g/cm³～0.04g/cm³And when the compression ratio is 50%, the compression resilience of the high-resilience silk fibroin aerogel is 50% -75%.

The principle of the invention is as follows: the silk fibroin can form a large amount of bubbles during stirring, but after pure bubbles are stirred, small bubbles spontaneously aggregate into large bubbles due to the action of surface tension, so that the diameters of the bubbles of the aerogel obtained after freeze drying are too large, and the material cannot be recovered due to the fact that part of the bubble structures are damaged in the compression process. The sugar micromolecule substance can generate a compatible blending system with the silk fibroin, so that the surface tension of the bubbles is increased, small bubbles formed by high-speed shearing cannot be easily aggregated into large bubbles, and the energy storage capacity of the aerogel is improved. In addition, a large number of hydrogen bonds are formed between glucose, xylose or fructose and silk fibroin, so that the viscosity of the mixed solution is improved, and gas can stably exist in the aerogel and is not easy to break. The bubbles are easy to break in the early stage of stirring, and the adoption of the hemispherical container or the bowl-shaped container can enable the broken bubble residual liquid to be better gathered at the bottom of the container to form more small bubbles so as to improve the compression strength of the aerogel. And the shape of the conical stirring rod is that the upper part is small and the lower part is large, so that liquid without bubbles formed at the bottom can be sheared more sufficiently, and the high-resilience silk fibroin aerogel is obtained.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following benefits:

(1) according to the invention, the shearing treatment is carried out on the mixed solution formed by the fibroin and the sugar micromolecules, and the aerogel obtained after freeze drying has a unique three-dimensional bubble structure, low density and high porosity;

(2) the silk fibroin aerogel prepared by the method cannot crack in the compression process, and has excellent energy storage capacity;

(3) the aerogel prepared based on silk fibroin has the advantages of good biocompatibility, degradability and the like, can be used for medical dressing, tissue repair and the like, can provide good biological environment for cell growth, adhesion and proliferation, and can also be used as a tissue culture scaffold;

(4) compared with pure silk element aerogel, the aerogel prepared by the invention has the compression rebound rate of 50-75% when the compression rate is 50%, and has good compression rebound performance.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a photograph of a high resilience silk fibroin aerogel prepared in the preferred embodiment 2 of the present invention;

fig. 2 is a schematic structural diagram of a high resilience silk fibroin aerogel in preferred embodiment 2 of the present invention;

FIG. 3 is a schematic view of a stirring rod in the preferred embodiment 2 of the present invention;

FIG. 4 is a schematic view of a bowl-shaped container according to the preferred embodiment 2 of the present invention;

in the attached drawing, high-resilience silk fibroin aerogel-1, closed air-2, free air-3, a conical stirring rod-4, a rotating rod-5, a stirring paddle-6 and a container-7.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not a whole embodiment. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1 preparation of aqueous solution of silk fibroin

Weighing 80g of silkworm cocoon shells by using a precision balance, preparing 4000mL of sodium bicarbonate/sodium carbonate aqueous solution with the mass fraction of 0.01M and the pH value of 9.5, heating the solution to boiling by using an induction cooker, adding the cocoon shells, adjusting the power of the induction cooker, keeping the aqueous solution to be boiled for 30min continuously, taking out cocoon silks, and cleaning the cocoon silks by using deionized water.

The above experiment is repeated for three times to remove sericin, and then cocoon filaments are taken out and placed in an oven at 60 ℃ to be dried to obtain pure silk fibroin fibers. Dissolving pure silk fibroin fiber in a lithium bromide solution with the concentration of 9.3mol/L according to the bath ratio of 20:150, and dissolving in a constant-temperature magnetic stirrer at the temperature of 60 +/-2 ℃ for about 1 h. Cooling, taking out, filling into a dialysis bag, sealing, dialyzing in deionized water for 3-4d, filtering with absorbent cotton to obtain pure silk fibroin solution, drying, weighing to obtain mass fraction of pure silk fibroin solution, and placing in a refrigerator at 4 deg.C for use.

Example 2 preparation of high resilience silk fibroin aerogel

(1) The concentration of the pure silk fibroin solution in example 1 was adjusted to 35mg/mL with deionized water to obtain an aqueous silk fibroin solution.

(2) Preparing 100mg/mL glucose aqueous solution, taking 200mL prepared silk fibroin aqueous solution, and adding the glucose aqueous solution into the silk fibroin aqueous solution to prepare mixed solution, wherein the concentration of glucose in the mixed solution is 4 mg/mL.

(3) Heating the mixed solution to 25 ℃, then pouring the mixed solution into a container 7, and carrying out high-speed shearing on the mixed solution at the temperature of 25 ℃ for 40min by using a stirrer, wherein the stirring speed is 1200r/min, so that the mixed solution forms a large amount of bubbles in the container 7, and the mixed solution is converted into a foam shape.

The container 7 in this embodiment is a hemispherical container or a bowl-shaped container, and the bowl-shaped container is shown in fig. 4, so that the broken bubble residual liquid can be better gathered at the bottom of the container 7.

The stirrer in this embodiment includes two conical stirring rods 4, and the conical stirring rods 4 are shaped such that the upper portion is smaller and the lower portion is larger, as shown in fig. 3, the conical stirring rods 4 in this embodiment include a rotating rod 5 located in the middle and a plurality of triangular stirring paddles 6 connected to the rotating rod 5, and the outer edges of the plurality of triangular stirring paddles 6 are located on a virtual conical surface. Specifically, the stirring paddles 6 are in a form similar to a triangle, a plurality of triangular stirring paddles 6 form a virtual conical surface, the side edges of the stirring paddles 6 are located on the side surface of the virtual conical surface, the bottom edge of the stirring paddles 6 is located on the bottom surface of the virtual conical surface, and the rotating rod 5 is connected to the vertex of the virtual conical surface, that is, the size of the stirring rod in the embodiment is gradually reduced from the bottom end to the top. Through the conical stirring rod 4 with the shape of big end down and small end up, liquid without bubbles at the bottom can be sheared more sufficiently, so that the high-resilience silk fibroin aerogel is obtained.

(4) Pouring the foamed mixed solution into a mold, and freeze-drying to obtain the silk fibroin aerogel, as shown in figure 1-2. The high-resilience silk fibroin aerogel 1 has a three-dimensional bubble structure of closed gas 2 and free gas 3, and the three-dimensional bubble structure is a structure formed by sealing a plurality of small bubbles in a solid material.

In the present embodiment, the conditions of freeze-drying are freezing at-45 ℃ for 6h, then gradually raising the temperature and vacuum-drying.

Example 3 preparation of high resilience silk fibroin aerogel

(1) The concentration of the pure silk fibroin solution in example 1 was adjusted to 45mg/mL with deionized water to obtain an aqueous silk fibroin solution.

(2) Preparing 100mg/mL xylose aqueous solution, taking 100mL prepared silk fibroin aqueous solution, and adding the xylose aqueous solution into the silk fibroin aqueous solution to prepare mixed solution, wherein the concentration of xylose in the mixed solution is 9 mg/mL.

(3) Heating the mixed solution to 28 ℃, then pouring the mixed solution into a container 7, and carrying out high-speed shearing on the mixed solution at the temperature of 25 ℃ for 25min by using a stirrer, wherein the stirring speed is 1000r/min, so that the mixed solution forms a large amount of bubbles in the container 7, and the mixed solution is converted into a foam shape.

The vessel 7 and stirrer in this example were the same as in example 2.

(4) Pouring the foamed mixed solution into a mold, and freeze-drying to obtain the silk fibroin aerogel, as shown in figure 1-2. The high-resilience silk fibroin aerogel 1 has a three-dimensional bubble structure of closed gas 2 and free gas 3, and the three-dimensional bubble structure is a structure formed by sealing a plurality of small bubbles in a solid material.

In the present embodiment, the conditions of freeze-drying are freezing at-60 ℃ for 5h, then gradually raising the temperature and vacuum-drying.

Example 4 preparation of high resilience silk fibroin aerogel

(1) Deionized water was used to adjust the concentration of the pure silk fibroin solution of example 1 to 60mg/mL, to obtain an aqueous silk fibroin solution.

(2) Preparing 100mg/mL fructose aqueous solution, taking 200mL prepared silk fibroin aqueous solution, and adding fructose aqueous solution into the silk fibroin aqueous solution to prepare mixed solution, wherein the concentration of fructose in the mixed solution is 15 mg/mL.

(3) Heating the mixed solution to 23 ℃, then pouring the mixed solution into a container 7, and carrying out high-speed shearing on the mixed solution at the temperature of 25 ℃ for 60min by using a stirrer, wherein the stirring speed is 800r/min, so that the mixed solution forms a large amount of bubbles in the container 7, and the mixed solution is converted into a foam shape.

The vessel 7 and stirrer in this example were the same as in example 2.

(4) Pouring the foamed mixed solution into a mold, and freeze-drying to obtain the silk fibroin aerogel, as shown in figure 1-2. The high-resilience silk fibroin aerogel 1 has a three-dimensional bubble structure of closed gas 2 and free gas 3, and the three-dimensional bubble structure is a structure formed by sealing a plurality of small bubbles in a solid material.

In the present embodiment, the conditions of freeze-drying are freezing at-70 ℃ for 6h, then gradually raising the temperature and vacuum-drying.

Example 5 preparation of high resilience silk fibroin aerogel

(1) Deionized water was used to adjust the concentration of the pure silk fibroin solution of example 1 to 50mg/mL, to obtain an aqueous silk fibroin solution.

(2) Preparing 100mg/mL glucose aqueous solution, taking 200mL prepared silk fibroin aqueous solution, and adding the glucose aqueous solution into the silk fibroin aqueous solution to prepare mixed solution, wherein the concentration of glucose in the mixed solution is 10 mg/mL.

(3) Heating the mixed solution to 26 ℃, then pouring the mixed solution into a container 7, and carrying out high-speed shearing on the mixed solution at the temperature of 25 ℃ for 50min by using a stirrer, wherein the stirring speed is 1300r/min, so that the mixed solution forms a large amount of bubbles in the container 7, and the mixed solution is converted into a foam shape.

The vessel 7 and stirrer in this example were the same as in example 2.

(4) Pouring the foamed mixed solution into a mold, and freeze-drying to obtain the silk fibroin aerogel, as shown in figure 1-2. The high-resilience silk fibroin aerogel 1 has a three-dimensional bubble structure of closed gas 2 and free gas 3, and the three-dimensional bubble structure is a structure formed by sealing a plurality of small bubbles in a solid material.

In the present embodiment, the conditions of freeze-drying are freezing at-50 ℃ for 8h, then gradually raising the temperature and vacuum-drying.

Comparative example 1 pure fibroin aerogel

The comparative example did not add carbohydrate when preparing pure silk fibroin aerogel. The specific preparation process can be seen in Chinese patent application No. 201610526187.8, namely the preparation process in the invention patent of 'a preparation method of silk fibroin aerogel'.

Example 6 testing and analysis

The silk fibroin aerogels prepared in examples 2 to 5 and comparative example 1 were tested for apparent density, compressive strength, and compression resilience, and the results are shown in table 1.

TABLE 1 test results

It can be seen from table 1 that compared with the pure silk fibroin aerogel of comparative example 1, the silk fibroin aerogel prepared in examples 2-5 has significantly improved compression resilience after being modified by adding saccharides in examples 2-5 under the premise of maintaining lower density and good compression strength.

The silk fibroin aerogel prepared by the method has a three-dimensional bubble structure, contains a large amount of closed air inside, is not communicated with the outside, and has a compression rebound rate as high as 50-75% when the compression rate is 50%. In addition, the aerogel also has the characteristics of low density, high porosity, good biocompatibility, degradability and the like, can be used for medical dressing, tissue repair and the like, can provide a good biological environment for cell growth, adhesion and proliferation, and can also be used as a tissue culture scaffold.

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the content of the present invention and implement the invention, and not to limit the scope of the invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the scope of the present invention.