CN106479195A - A kind of nano-cellulose strengthens fibroin albumen composite material and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of polymer materials, in particular to a nanocellulose-reinforced silk fibroin composite material and a preparation method thereof. LiBr is used as a common solvent to dissolve silk fibers and cellulose, and by controlling the degree of dissolution of cellulose raw materials, the retention The nanostructure of cellulose; the dissolution temperature of cellulose is controlled at 80~150°C; the obtained silk fibroin/cellulose blend solution can quickly form a gel, avoiding the aggregation and uneven distribution of nanocellulose in the solution; the After the gel is further dried, membrane-forming and porous materials can be prepared to obtain nanocellulose-reinforced silk fibroin composites. The preparation process of the invention is simple and controllable; the obtained composite material contains uniformly distributed nano-cellulose, and its strength and elongation at break are significantly enhanced compared with regenerated silk fibroin materials.

Description

A kind of nano-cellulose reinforced silk fibroin composite material and preparation method thereof

technical field

The invention relates to the technical field of polymer materials, in particular to a nanocellulose-reinforced silk fibroin composite material and a preparation method thereof.

Background technique

Silk fibroin is a high-purity protein secreted by silk glands of silkworms. It does not contain organelles and other biological impurities, and has high biological safety. Silk fibroin is composed of 20 amino acids such as tyrosine, alanine, and serine, which can be biodegraded and the final degradation products are polypeptides and free amino acids, which are easily metabolized by the body. Silk fibroin has good biocompatibility. Silk fibers have been used in medical surgical sutures for decades, and the clinical effect has been proven. In vitro and in vivo results confirmed that the regenerated silk fibroin material can support the growth of a variety of cells, showing immunological inertness and lower inflammatory response. Therefore, silk fibroin is an ideal polymer raw material for preparing biomedical materials. At present, silk fibroin materials have been widely used in the research of skin, ligament, blood vessel and other tissue repair.

As a natural protein fiber, silk fiber has excellent mechanical properties. However, in order to obtain materials in different forms, such as membranes, porous scaffolds, tubular scaffolds, etc., it is necessary to dissolve silk fibroin fibers to form a regenerated silk fibroin solution. During the dissolution and regeneration process, the crystal structure of silk fiber was obviously destroyed, and the silk macromolecules were degraded, and the molecular weight decreased. Compared with natural silk fibers, the mechanical properties of materials prepared from regenerated silk fibroin are significantly lower, and it is difficult to meet the needs of some tissue engineering materials, such as bone tissue engineering scaffolds and artificial blood vessels.

Nanocellulose is a kind of rigid rod-shaped cellulose or cellulose nanofibrils extracted from natural cellulose with a diameter of 1-30 nm and a length of tens of nanometers to hundreds of microns. Nanocellulose has high degree of polymerization and crystallinity, high strength and high modulus, and nanocellulose is degradable, renewable and biocompatible, showing great application prospects in the field of high-performance biomaterials. Due to the high-performance mechanical characteristics, the use of nanocellulose dispersed phase to enhance regenerated silk fibroin materials can obtain composite materials with excellent mechanical properties. Moreover, cellulose contains a large amount of -OH, which can form a large number of hydrogen bonds with the -COOH and _-NH2 groups of silk fibroin. The increase of this intermolecular interaction can further improve the mechanical properties of the material. On the other hand, during the application of tissue engineering scaffolds, nanocellulose compounded into scaffold materials can provide guidance signals for cell adhesion and migration.

In order to obtain nanocellulose-reinforced composites, the current main method is to extract cellulose nanowhiskers or fibrils, and then blend them with polymers. This method is not only cumbersome, but it is difficult to uniformly disperse the obtained nanocellulose in the polymer solution, which greatly limits its application range. Therefore, it is of great significance to develop a simple and effective method to obtain stable cellulose nanofibrils and uniformly disperse them in the silk fibroin matrix for the preparation of high-performance silk fibroin composites. Before the present invention, a Chinese invention patent (CN103498210) prepared a high-strength silk fibroin fiber, blending cellulose nano-whiskers with concentrated silk fibroin solution for wet spinning to prepare composite fibers. However, this method first needs to extract the cellulose nano whiskers, and the process is complicated. Moreover, the cellulose nano whiskers are easy to agglomerate, and it is difficult to evenly disperse in the silk solution to form uniform fibers.

In view of the above defects, the present inventor invented a method for preparing nanocellulose-reinforced silk fibroin composite material through active research and innovation, so that the silk fibroin material has more industrial utilization value.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a simple and effective method for preparing nanocellulose-reinforced silk fibroin composite materials.

The purpose of the present invention is achieved through the following technical solutions:

A preparation method of nano-cellulose reinforced silk fibroin composite material, comprising the following steps:

S1. Dissolve the degummed silk fibroin fiber in LiBr, mix and dissolve evenly, and the dissolving bath ratio is 1:4-20 to obtain a silk fibroin solution;

S2. Dissolving cellulose in LiBr, mixing and dissolving evenly, the dissolving bath ratio is 1:50-200, to obtain a uniform and transparent cellulose solution;

S3. Mixing the silk fibroin solution and the cellulose solution evenly, and performing a defoaming treatment to obtain a blend;

S4. Cool the blend to form a gel, then soak the gel in an alcohol solution with a mass concentration of 50-100% for 0.5-5 hours, and then rinse with water to obtain a purified silk fibroin/cellulose gel.

Further, in the steps S1 and S2, the concentration of LiBr is 5-10mol/L.

Further, in the step S1, the dissolving condition of the silk fibroin fiber is stirring and mixing at 40-70° C. for 0.5-4 hours, so as to avoid the reduction of the molecular weight of the silk fibroin due to excessive temperature and long time.

Further, in the step S2, the dissolving condition of the cellulose is stirring and mixing at 80-150° C. for 0.5-5 hours to avoid damage to the nanostructure of the cellulose by excessively high temperature and long time.

Further, in the step S3, the condition for mixing the silk fibroin solution and the cellulose solution is to stir and mix at 80-110° C. for 3-10 minutes.

Further, the cellulose described in the step S2 comes from at least one of the following cellulose raw materials: cotton, cotton linters, cotton pulp, wood pulp fibers, wood pulp, absorbent cotton, cellulose filter paper, micro Crystalline cellulose, wood, plant straw and its cellulose products.

Furthermore, the degree of polymerization of the cellulose is 150-1500.

Further, in the above step S3, the silk fibroin solution and the cellulose solution are blended at a mass ratio of silk fibroin to cellulose of 0.25-4:1.

Further, the alcohol solution in step S4 is at least one of methanol, ethanol, isopropanol, butanol, isobutanol and tert-butanol.

A nanocellulose-reinforced silk fibroin composite material is prepared by the above method.

The application of the nanocellulose-reinforced silk fibroin composite material includes drying to form a film, or freeze-drying to prepare a porous material.

The beneficial effects of the present invention are:

1. The present invention dissolves cellulose with LiBr, retains the nanostructure of natural cellulose during the dissolution process, and can directly obtain nanocellulose suspension by controlling the dissolution conditions;

2. In the preparation method of the present invention, the cellulose solution can quickly form a gel after cooling, so that the nano-cellulose is evenly dispersed in the silk fibroin/cellulose mixed gel, and the occurrence of nano-cellulose in the dried composite material is avoided. Cellulose aggregation and uneven distribution;

3. The present invention uses LiBr as a common solvent to dissolve silk fibroin and cellulose, does not require the joint use of various chemical reagents, and the preparation process is simple, controllable and safe.

Description of drawings

Fig. 1 is the electron micrograph of the surface of silk fibroin/cellulose blend film in the preparation process of embodiment 1;

Fig. 2 is the electron micrograph of the section of silk fibroin/cellulose blend film in the preparation process of embodiment 1;

Fig. 3 is the stress-strain curve of the silk fibroin/cellulose blend film that embodiment 1 obtains;

FIG. 4 is an electron micrograph of the silk fibroin/cellulose porous material obtained in Example 2.

detailed description

The present invention will be described in further detail below through specific implementation methods and drawings, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the above-mentioned method idea of the present invention, various replacements or changes made according to common technical knowledge and customary means in this field shall be included in the scope of the present invention.

Example 1

Immerse 100 g of silkworm raw silk in 5 L of 0.05% NaCO ₃ solution, boil it at 98-100°C for 30 min, repeat 3 times to degumming the silk, wash and dry it thoroughly to obtain pure silk fibroin fiber; 10 g of degummed silk The fibroin fiber was added to 50 mL of 9.3 mol/L LiBr solution, stirred and dissolved at 60°C for 55 min to obtain a silk fibroin mixed solution;

Add 1 g of microcrystalline cellulose powder into 80 mL of 9.3 mol/L LiBr solution, stir and dissolve at 110°C for 55 min to obtain a cellulose solution;

Mix the silk fibroin solution and cellulose solution according to the mass ratio of silk fibroin and fiber 50:50, stir at 110°C for 5 minutes and mix evenly to obtain a silk fibroin/cellulose mixed solution, cool at room temperature to form a blended gel glue;

The above gel was soaked in 75% ethanol for 2 h, and then soaked in flowing deionized water for 48 h to remove LiBr;

The purified silk fibroin/cellulose gel was dried in a vacuum oven at 37 °C for 48 h to obtain a nanocellulose-reinforced silk film.

The silk fibroin membrane that the nanocellulose that obtains in the preparation process of embodiment 1 is strengthened is done electron microscope detection, and detection result is as shown in Figure 1 and Figure 2; The silk fibroin membrane that the nanocellulose that is obtained in embodiment 1 is strengthened carries out mechanical test, And compared with the pure silk film prepared from the regenerated silk fibroin solution obtained by LiBr dissolution and dialysis, the test results are shown in Figure 3.

Example 2

Add 20 g of degummed silk fibroin fibers to 100 mL of 10 mol/L LiBr solution, stir and dissolve at 60°C for 58 min to obtain a silk fibroin mixed solution;

Add 2 g of microcrystalline cellulose powder into 160 mL of 10 mol/L LiBr solution, stir and dissolve at 110°C for 58 min to obtain a cellulose solution;

Mix the silk fibroin solution and the cellulose solution according to the mass ratio of silk fibroin and fiber 20:80, stir at 110° C. for 3 minutes and mix evenly to obtain a silk fibroin/cellulose mixed solution. Cooling at room temperature to form a blended gel;

The above gel was soaked in 50% ethanol for 2 h, and then soaked in running water for 48 h to remove LiBr;

The purified silk fibroin/cellulose gel was dehydrated successively with 50%, 75% tert-butanol and anhydrous tert-butanol for 30 min, and then frozen at -20°C for 24 h to obtain frozen solids.

The above-mentioned frozen solid was freeze-dried for 48 h according to the conventional method to obtain a nanocellulose-reinforced silk fibroin porous material.

The nanocellulose-reinforced silk fibroin porous material obtained in the preparation process of Example 2 was subjected to electron microscope detection, and the detection results are shown in FIG. 4 .

Example 3

Add 10 g of degummed silk fibroin fibers to 40 mL of 8 mol/L LiBr solution, stir and dissolve at 60°C for 120 min to obtain a silk fibroin mixed solution;

Add 1 g of cellulose filter paper into 100 mL of 8 mol/L LiBr solution, stir and dissolve at 90 °C for 4 h to obtain a cellulose solution;

Mix the silk fibroin solution and cellulose solution according to the mass ratio of silk fibroin and fiber 80:20, stir at 90°C for 5 min and mix well to obtain a silk fibroin/cellulose mixed solution; cool at room temperature to form a blended gel;

Soak the above gel in 90% methanol for 1 h, then soak in running water for 72 h to remove LiBr;

The purified silk fibroin/cellulose gel was dried in a vacuum oven at 37 °C for 48 h to obtain a nanocellulose-reinforced silk film.

Example 4

Add 10 g of degummed silk fibroin fibers to 40 mL of 5 mol/L LiBr solution, stir and dissolve at 60°C for 120 min to obtain a silk fibroin mixed solution;

Add 1 g of cellulose filter paper into 100 mL of 5 mol/L LiBr solution, stir and dissolve at 90 °C for 4 h to obtain a cellulose solution;

Mix the silk fibroin solution and cellulose solution according to the mass ratio of silk fibroin and fiber 80:20, stir at 90°C for 10 minutes and mix evenly to obtain a silk fibroin/cellulose mixed solution; cool at room temperature to form a blended gel glue;

Soak the above gel in 100% methanol for 1 h, then soak in running water for 72 h to remove LiBr;

The purified silk fibroin/cellulose gel was dried in a vacuum oven at 37 °C for 48 h to obtain a nanocellulose-reinforced silk film.

The above descriptions are only preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and Modifications can be made within the scope of the ideas described herein, by virtue of the above teachings or skill or knowledge in the relevant art. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (10)

1. A preparation method of nano-cellulose reinforced silk fibroin composite material, characterized in that, comprising the following steps: S1. Dissolve the degummed silk fibroin fiber in LiBr, mix and dissolve evenly, and the dissolving bath ratio is 1:4-20 to obtain a silk fibroin solution; S2. Dissolving cellulose in LiBr, mixing and dissolving evenly, the dissolving bath ratio is 1:50-200, to obtain a uniform and transparent cellulose solution; S3. Mixing the silk fibroin solution and the cellulose solution evenly, and performing a defoaming treatment to obtain a blend; S4. Cool the blend to form a gel, then soak the gel in an alcohol solution with a mass concentration of 50-100% for 0.5-5 hours, and then rinse with water to obtain a purified silk fibroin/cellulose gel. 2. The method for preparing a nanocellulose-reinforced silk fibroin composite material according to claim 1, characterized in that, in the steps S1 and S2, the concentration of LiBr is 5-10mol/L. 3. A method for preparing a nanocellulose-reinforced silk fibroin composite material according to claim 1, characterized in that, in the step S1, the dissolving condition of the silk fiber is stirring and mixing at 40-70°C 0.5-4h; in the step S2, the dissolution condition of cellulose is stirring and mixing at 80-150°C for 0.5-5h. 4. the preparation method of a kind of nano-cellulose reinforced silk fibroin composite material according to claim 1, is characterized in that, in described step S3, the condition that silk fibroin solution and cellulose solution mix is, at 80- Stir and mix at 110°C for 3-10min. 5. the preparation method of a kind of nano-cellulose reinforced silk fibroin composite material according to claim 1, is characterized in that, the cellulose described in the described step S2 is from at least one in the following cellulose raw materials: Cotton, cotton linters, cotton pulp, wood pulp fiber, wood pulp, absorbent cotton, cellulose filter paper, microcrystalline cellulose, wood, plant straw and its cellulose products. 6 . The method for preparing a nanocellulose-reinforced silk fibroin composite material according to claim 5 , wherein the degree of polymerization of the cellulose is 150-1500. 7. The preparation method of a kind of nano-cellulose reinforced silk fibroin composite material according to claim 1, characterized in that, in the described step S3, the mass ratio of silk fibroin to cellulose is 0.25-4: 1 to blend the silk fibroin solution and the cellulose solution. 8. the preparation method of a kind of nano-cellulose reinforced silk fibroin composite material according to claim 1, is characterized in that, in described step S4, alcohol solution is methanol, ethanol, isopropanol, butanol, isobutanol , at least one of tert-butanol. 9. A nanocellulose-reinforced silk fibroin composite material, characterized in that it is prepared by the method described in any one of claims 1-8. 10. The application of a nanocellulose-reinforced silk fibroin composite material, characterized in that it comprises drying to form a film, or freeze-drying to prepare a porous material.