A dual crosslinking network material, and a preparation method and application thereof

Abstract

The application discloses a kind of double crosslinking network materials and its preparation method and application, the preparation method includes: (1) the contact, reaction of keratin solution and aldehyde group dextran aqueous solution, obtain preliminary crosslinking network;(2) preliminary crosslinking network and dopamine solution are mixed, and heat preservation, obtain double crosslinking network material.The application utilizes natural biomass raw material (keratin, dextran) and biocompatibility molecule (dopamine), by double crosslinking synergistic effect, the mechanical properties and biocompatibility of material are promoted, satisfy the demand in biological medical field.

Description

Technical Field

[0001] This invention belongs to the field of biomaterials technology, and more specifically, relates to a double cross-linked network material, its preparation method, and its application. Background Technology

[0002] With an aging population and rising prevalence of chronic diseases, the global wound care market is experiencing significant growth, particularly with an increasing demand for advanced functional dressings. Traditional wound dressings (such as gauze and sponges) suffer from poor moisture retention, easy adhesion to the wound leading to secondary damage, and the need for frequent changes. Hydrogel materials, due to their high water content, three-dimensional network structure, and excellent biocompatibility, are widely considered one of the ideal dressing candidates. They can provide a moist healing environment, absorb wound exudate, and promote cell migration and proliferation.

[0003] Keratin is a natural protein widely found in natural biomass such as hair and feathers, thus exhibiting extremely low immunogenicity and excellent biocompatibility, and does not induce severe immune rejection. Simultaneously, keratin scaffolds can mimic the structure of the natural extracellular matrix, providing physical support and biochemical signals to cells, guiding orderly cell growth and tissue remodeling. However, current hydrogel materials based on keratin and cross-linking agents suffer from insufficient mechanical properties and poor biocompatibility. Summary of the Invention

[0004] The purpose of this invention is to provide a double-crosslinked network material, its preparation method, and its application. This invention utilizes natural biomass raw materials (keratin, dextran) and biocompatible molecules (dopamine) to improve the mechanical properties and biocompatibility of the material through the synergistic effect of double crosslinking, thereby meeting the needs of the biomedical field.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a double-crosslinked network material, the method comprising: (1) Keratin solution was contacted and reacted with aldehyde-modified dextran aqueous solution to obtain a preliminary cross-linked network; (2) The preliminary cross-linked network and dopamine solution are mixed and kept warm to obtain a double cross-linked network material.

[0006] In this invention, the chemical cross-linking of keratin and aldehyde-modified dextran involves a Schiff base reaction to form an imine bond between the primary amino group of keratin and the aldehyde group of aldehyde-modified dextran, resulting in a preliminary cross-linking network. Specifically, the primary amino group (-NH2) of keratin undergoes a Schiff base reaction with the aldehyde group (-CHO) of aldehyde-modified dextran: -NH2 + -CHO → -N=CH- (imine bond), and the system gradually forms a gel-like preliminary cross-linking network.

[0007] Construction of double crosslinked networks: Dopamine is added to the preliminary crosslinked network system, and hydrogen bonds are formed between dopamine molecules and groups in the network to obtain double crosslinked network materials.

[0008] In this invention, the catechol groups of dopamine molecules form strong hydrogen bonds with the amino groups of keratin and the hydroxyl groups of aldehyde-modified dextran in the network. At the same time, hydrogen bonds can also be formed between dopamine molecules, ultimately resulting in a uniform and elastic double-crosslinked network material.

[0009] The core of this invention is to prepare double cross-linked network materials through a four-step process of "extraction-modification-chemical cross-linking-physical cross-linking".

[0010] According to the present invention, preferably, in step (1), the keratin solution is prepared by a method comprising: dissolving keratin powder in PBS buffer to obtain the keratin solution, wherein the ratio of keratin powder to PBS buffer is 1:(4-6) g / mL; The pH of the PBS buffer is 8-10, and the concentration is 0.01-0.02 mol / L; The mass concentration of the aldehyde-modified dextran aqueous solution is 4%-10%.

[0011] According to the present invention, preferably, in step (1), the keratin solution and the aldehyde-modified dextran aqueous solution are contacted and reacted at a mass ratio of 1:(1-5) of keratin and aldehyde-modified dextran; The reaction is carried out at a temperature of 25-40℃ for 2-5 hours.

[0012] According to the present invention, preferably, in step (1), the keratin is derived from hair, which is animal hair, preferably at least one of wool, human hair and feathers.

[0013] In this invention, the hair is further preferably wool, because it is abundant and has a high keratin content.

[0014] According to the present invention, preferably, keratin is obtained by a method comprising the following steps: pretreating the hair, and then extracting and purifying the pretreated hair by a reduction method to obtain the keratin.

[0015] According to the present invention, preferably, the pretreatment includes: soaking the hair in an aqueous solution of sodium dodecyl sulfate, then washing it with water until neutral, and finally drying and cutting it into pieces; wherein the mass fraction of the aqueous solution of sodium dodecyl sulfate is 1%-2%; the soaking time is 1-3 hours; and the hair is cut into pieces to 1-2 mm. The reduction extraction method includes: mixing and reacting pretreated hair, Tris-HCl buffer, and β-mercaptoethanol to obtain a reaction solution containing keratin; wherein, in the reduction extraction method, the pH of the Tris-HCl buffer is 7-9 and the concentration is 0.1-0.2 mol / L; the ratio of pretreated hair to Tris-HCl buffer is 1:(15-25) g / mL; the amount of β-mercaptoethanol added is 5%-10% of the mass of the pretreated hair; the reaction temperature is 50-60℃ and the time is 4-6 h; The purification process includes: centrifuging the reaction solution containing keratin and collecting the supernatant; then precipitating the supernatant with alcohol, centrifuging to collect the precipitate; redissolving the precipitate with water and dialyzing; finally, freeze-drying the dialysate to obtain keratin; wherein, the alcohol precipitation uses anhydrous ethanol, and the volume ratio of anhydrous ethanol to supernatant is 1:(2-4); the dialysis uses a dialysis bag, and the dialysis bag has a molecular weight cutoff of 8000-14000 Da.

[0016] In this invention, the hair is soaked in an aqueous solution of sodium dodecyl sulfate to remove surface grease and impurities.

[0017] In this invention, hair before pretreatment refers to hair that has not undergone the above pretreatment.

[0018] According to the present invention, preferably, the aldehyde-modified dextran is prepared by a method comprising the following steps: placing an aqueous dextran solution in a light-proof container, adding sodium periodate, and stirring the reaction; then adding ethylene glycol to the reaction solution to terminate the reaction; next, placing the mixture obtained after terminating the reaction into a dialysis bag and dialyzing with water; finally, freeze-drying the dialysate to obtain the aldehyde-modified dextran. The dextran aqueous solution has a mass concentration of 4%-10%; the molecular weight of the dextran used is 50,000-100,000 Da; the molar ratio of dextran to sodium periodate is 1:(0.5-2); and the stirring reaction time is 2-3 h.

[0019] In this invention, the synthesis mechanism of aldehyde-modified dextran is shown in the diagram below. Figure 2 As shown.

[0020] In this invention, the method for preparing aldehyde-modified dextran involves dialysis with water to remove unreacted sodium periodate and ethylene glycol.

[0021] In this invention, a light-proof container is used to prevent the decomposition of sodium periodate.

[0022] According to the present invention, preferably, in step (2), the dopamine solution is prepared by the following steps: dissolving dopamine hydrochloride in PBS buffer to obtain a dopamine solution; the pH of the PBS buffer is 7-9 and the concentration is 0.01-0.02 mol / L; The mass of dopamine hydrochloride added is 5%-20% of the total mass of keratin and aldehyde-modified dextran; Keep warm at 25-37℃ for 1-2 hours.

[0023] In this invention, preferably, in step (2), after heat preservation, the double cross-linked network material is rinsed.

[0024] A second aspect of the present invention provides a double cross-linked network material prepared by the above-described preparation method.

[0025] A third aspect of the present invention provides the application of the above-described dual cross-linked network material as a biomedical dressing or tissue engineering scaffold.

[0026] The technical solution of the present invention has the following beneficial effects: (1) Raw material advantages: Keratin comes from waste hair, and dextran is a natural polysaccharide. The raw materials are renewable and low in cost, which is in line with the concept of green environmental protection; dopamine has excellent biocompatibility and no cytotoxicity.

[0027] (2) Performance advantages: Chemical cross-linking (imine bond) ensures network stability, physical cross-linking (hydrogen bond) enhances material toughness, and the synergistic effect of dual cross-linking improves the tensile strength and swelling rate of the material.

[0028] (3) Process advantages: The reaction conditions are mild (room temperature / near body temperature, no toxic catalyst required), the operation is simple, and it is easy to scale up industrial production.

[0029] (4) Application advantages: The material has both biocompatibility and water absorption, and can be used as a biomedical dressing (to promote wound healing) and tissue engineering scaffold (such as skin tissue repair), with broad application prospects.

[0030] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0031] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0032] Figure 1 A process diagram of keratin extraction according to an embodiment of the present invention is shown.

[0033] Figure 2A schematic diagram illustrating the synthesis mechanism of aldehyde-modified dextran according to the present invention is shown.

[0034] Figure 3 A physical image of the double cross-linked network hydrogel material prepared according to Example 1 of the present invention is shown.

[0035] Figure 4 An electron micrograph of a gel-like preliminary cross-linked network prepared by chemical cross-linking only according to Example 1 of the present invention is shown.

[0036] Figure 5 The electron micrograph of the double cross-linked network hydrogel material prepared according to Example 1 of the present invention is shown.

[0037] Figures 6-8 The swelling rate test results of the preliminary cross-linked network and double cross-linked network materials prepared according to embodiments of the present invention are shown in the figure. Figures 6-8 In this context, Time represents time, and Swelling ratio represents the swelling rate.

[0038] Figures 9-11 The tensile stress-strain results of preliminary cross-linked network and double cross-linked network materials prepared according to embodiments of the present invention are shown respectively. Figures 9-11 In this context, stress refers to stress, and strain refers to strain.

[0039] Figure 12 A schematic diagram of the specimen configuration for the tensile test according to Test Example 3 of the present invention is shown.

[0040] in, Figures 6-11 In this context, CPS1, CPS2, and CPS3 represent the double crosslinked network materials prepared in Examples 1-3, respectively; CS1, CS2, and CS3 represent the preliminary crosslinked network materials prepared by chemical crosslinking only in Examples 1-3, respectively. Detailed Implementation

[0041] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0042] The present invention is further illustrated by the following examples: In the following examples: the dopamine hydrochloride used was provided by Aladdin, with CAS number 62-31-7 and purity of 98%.

[0043] Example 1

[0044] A. Hair pretreatment and keratin extraction: such as Figure 1 As shown, (1) Hair pretreatment: Take 15 g of wool (the fiber diameter is finer and the keratin extraction rate is higher), soak it in 2% sodium dodecyl sulfate aqueous solution for 2 h, rinse with deionized water until neutral, dry at 60℃ and cut into 1.5 mm. (2) Keratin extraction: Add 300 mL of Tris-HCl buffer (pH=8.5, 0.1 mol / L) at a material-to-liquid ratio of 1:20 g / mL of wool (i.e., wool that has not undergone the above pretreatment) and Tris-HCl buffer, add 1.2 g of β-mercaptoethanol (the amount added is 8% of the mass of wool that has not undergone the above pretreatment), stir in a constant temperature water bath at 60℃ for 6 h; centrifuge at 4000 r / min for 15 min, take the supernatant and add 3 times the volume of anhydrous ethanol, let stand for 2 h and then centrifuge to collect the precipitate; reconstitute the precipitate with water and dialyze it with a dialysis bag with a molecular weight cutoff of 10000 Da for 3 days, changing the water 3 times a day, freeze-dry the dialysate to obtain 3.5 g of keratin powder.

[0045] B. Preparation of aldehyde-modified dextran: Weigh 8 g of dextran (molecular weight 100,000 Da, high molecular weight improves network rigidity) and dissolve it in 80 mL of deionized water. Add the solution to a light-protected container and then add 5.5 g of sodium periodate (molar ratio of dextran to sodium periodate 1:1.5). Stir magnetically at 25°C in the dark for 3 h. Add 1.2 mL of ethylene glycol to terminate the reaction. Put the mixture obtained after the termination reaction into a dialysis bag (molecular weight cutoff 10,000 Da) and dialyze with water for 3 days. Freeze-dry the dialysate to obtain 6.8 g of aldehyde-modified dextran.

[0046] C. Chemical cross-linking: 0.3 g of keratin powder was dissolved in 15 mL of PBS buffer (pH=10, concentration 0.01 mol / L, alkaline environment accelerates Schiff base reaction) to obtain a keratin solution; 1.5 g of aldehyde-modified dextran was dissolved in 15 mL of deionized water to obtain an aldehyde-modified dextran solution; the keratin solution was slowly injected into the aldehyde-modified dextran solution (keratin to aldehyde-modified dextran mass ratio 1:5), and the reaction was carried out at 37℃ with magnetic stirring for 4 h to form a dense gel-like preliminary cross-linked network.

[0047] D. Construction of dual crosslinks: Weigh 0.36 g of dopamine hydrochloride and dissolve it in 2 mL of PBS buffer (pH=8.5, concentration 0.01 mol / L) to obtain a dopamine solution. Slowly add the dopamine solution dropwise into the preliminary crosslinked network (the added mass of dopamine hydrochloride is 20% of the total mass of keratin and aldehyde-modified dextran; higher addition increases hydrogen bond density). Stir gently for 5 min; incubate at 37℃ for 2 h, during which time the dopamine catechol groups form dense hydrogen bonds with the amino and hydroxyl groups in the network; rinse three times with deionized water to remove unreacted dopamine hydrochloride and small molecule impurities, obtaining an elastic blocky material (dual crosslinked network material, such as...). Figure 3 (As shown).

[0048] Example 2

[0049] A. Hair pretreatment and keratin extraction: such as Figure 1 As shown, (1) Hair pretreatment: Take 12 g of human hair (from readily available sources), soak it in a 1.5% sodium dodecyl sulfate aqueous solution for 2 h, rinse with deionized water until neutral, dry at 60°C and then cut into 1 mm pieces. (2) Keratin extraction: Add 240 mL of Tris-HCl buffer (pH=8.5, 0.1 mol / L) at a ratio of 1:20 g / mL of hair (i.e., hair that has not undergone the above pretreatment) to Tris-HCl buffer. Add 0.6 g of β-mercaptoethanol (the amount added is 5% of the mass of the hair that has not undergone the above pretreatment, and the amount of low reducing agent is used to retain some disulfide bonds). Stir the reaction in a constant temperature water bath at 50℃ for 4 h. Centrifuge at 4000 r / min for 15 min. Add 3 times the volume of anhydrous ethanol to the supernatant. After standing for 2 h, centrifuge to collect the precipitate. Redissolve the precipitate in water and dialyze it through a dialysis bag with a molecular weight cutoff of 10000 Da for 3 days, changing the water 3 times a day. Freeze-dry the dialysate to obtain 2.3 g of keratin powder.

[0050] B. Preparation of aldehyde-modified dextran: Weigh 6 g of dextran (molecular weight 50,000 Da, lower molecular weight improves hydrophilicity) and dissolve it in 120 mL of deionized water. Add the solution to a light-protected container and then add 2.1 g of sodium periodate (molar ratio of dextran to sodium periodate 1:0.5). Stir at 25°C in the dark for 2 h. Add 0.5 mL of ethylene glycol to terminate the reaction. Put the mixture obtained after the reaction termination into a dialysis bag (molecular weight cutoff 10,000 Da) and dialyze with water for 3 days. Freeze-dry the dialysate to obtain 5.1 g of aldehyde-modified dextran.

[0051] C. Chemical cross-linking: 0.2 g of keratin powder was dissolved in 10 mL of PBS buffer (pH=8, concentration 0.01 mol / L, weak alkalinity slows down the reaction rate) to obtain a keratin solution; 0.2 g of aldehyde-modified dextran was dissolved in 4 mL of deionized water to obtain an aldehyde-modified dextran solution; the keratin solution was slowly injected into the aldehyde-modified dextran solution (keratin to aldehyde-modified dextran mass ratio 1:1), and the mixture was stirred at 25℃ for 2 h to form a loose and porous preliminary cross-linking network.

[0052] D. Construction of double crosslinking: Weigh 0.04 g of dopamine hydrochloride and dissolve it in 1 mL of PBS buffer (pH=8.5, concentration 0.01 mol / L) to obtain a dopamine solution. Slowly add the dopamine solution dropwise into the preliminary crosslinking network (the added mass of dopamine hydrochloride is 10% of the total mass of keratin and aldehyde-modified dextran), and stir gently for 5 min. Keep it at 25℃ for 1 h to reduce excessive hydrogen bond density. Rinse three times with deionized water to remove unreacted dopamine hydrochloride and small molecule impurities to obtain an elastic block material (double crosslinking network material).

[0053] Example 3

[0054] A. Hair pretreatment and keratin extraction: such as Figure 1 As shown, (1) Hair pretreatment: Take 10 g of wool and mix it with human hair (mass ratio 1:1, combining the advantages of high wool extraction rate and high hair purity), soak it in 2% sodium dodecyl sulfate aqueous solution for 2 h, rinse it with deionized water until neutral, dry it at 60℃ and cut it into 1.2 mm. (2) Keratin extraction: Add 200 mL of Tris-HCl buffer (pH=8.5, 0.1 mol / L) at a ratio of 1:20 g / mL of hair (i.e., hair that has not undergone the above pretreatment) to Tris-HCl buffer. Add 1.0 g of β-mercaptoethanol (the amount added is 10% of the mass of the hair that has not undergone the above pretreatment; a higher amount of reducing agent will break more disulfide bonds and reduce intermolecular forces). Stir the reaction in a constant temperature water bath at 60℃ for 6 h. Centrifuge at 4000 r / min for 15 min, take the supernatant, add 3 times the volume of anhydrous ethanol, let stand for 2 h, and then centrifuge to collect the precipitate. Redissolve the precipitate in water and dialyze it with a dialysis bag with a molecular weight cutoff of 10000 Da for 3 days, changing the water 3 times a day. Freeze-dry the dialysate to obtain 2.2 g of keratin powder.

[0055] B. Preparation of aldehyde-modified dextran: Weigh 5 g of dextran (molecular weight 50,000 Da) and dissolve it in 50 mL of deionized water. Add the solution to a light-protected container and then add 3.7 g of sodium periodate (molar ratio of dextran to sodium periodate 1:1.2). Stir at 25°C in the dark for 2.5 h. Add 0.8 mL of ethylene glycol to terminate the reaction. Put the mixture obtained after the reaction termination into a dialysis bag (molecular weight cutoff 10,000 Da) and dialyze with water for 3 days. Freeze-dry the dialysate to obtain 4.1 g of aldehyde-modified dextran.

[0056] C. Chemical cross-linking: 0.2 g of keratin powder was dissolved in 10 mL of PBS buffer (pH=8.5, concentration 0.01 mol / L) to obtain a keratin solution; 0.4 g of aldehyde-modified dextran was dissolved in 4 mL of deionized water to obtain an aldehyde-modified dextran solution; the keratin solution was slowly injected into the aldehyde-modified dextran solution (keratin to aldehyde-modified dextran mass ratio 1:2), and the reaction was stirred at 25℃ for 2.5 h. Shortening the reaction time reduced the density of cross-linking points, and a preliminary cross-linked network was obtained.

[0057] D. Construction of double crosslinking: Weigh 0.06 g of dopamine hydrochloride and dissolve it in 1 mL of PBS buffer (pH=8.5, concentration 0.01 mol / L) to obtain a dopamine solution. Slowly add the dopamine solution dropwise into the preliminary crosslinking network (the added mass of dopamine hydrochloride is 10% of the total mass of keratin and aldehyde-modified dextran), and stir gently for 5 min; incubate at 25℃ for 1 h to shorten the hydrogen bond formation time; rinse 3 times with deionized water to remove unreacted dopamine hydrochloride and small molecule impurities to obtain an elastic block material (double crosslinking network material).

[0058] Test Example 1

[0059] Electron microscopy was performed on the gel-like preliminary cross-linked network prepared by chemical cross-linking only in step C of Example 1 and the elastic block material prepared in step D. The results showed that... Figure 4 and Figure 5 As shown.

[0060] Test Example 2

[0061] The swelling rate of the preliminary cross-linked network prepared by chemical cross-linking only in step C of the above embodiments and the elastic block material prepared in step D were measured respectively. The specific test methods are as follows, and the test results are shown in [the table below]. Figures 6-8 .

[0062] Swelling rate test method: Sample preparation: The hydrogel was vacuum dried at 60℃ and then prepared into standard-sized cubes (10×10×2mm). Its mass W was recorded. o .

[0063] Swelling process: Immerse the sample in a container with a sufficient amount of deionized water and soak it at a constant temperature of 37°C.

[0064] Data measurement: Mass method: Samples were taken at predetermined time points (10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 70 min, 100 min, 130 min), excess liquid was gently blotted off with filter paper, and the samples were quickly weighed (wet weight W). t ).

[0065] Result calculation: Swelling Ratio (SR): SR = (W t - W o ) / W o × 100%.

[0066] Test Example 3

[0067] Tensile tests were performed on the preliminary cross-linked network prepared by chemical cross-linking only in step C of the above embodiments and the elastic block material prepared in step D. The specific test methods are as follows, and the test results are shown in [the table below]. Figures 9-11 .

[0068] Tensile tests were performed on the samples using an electronic universal testing machine manufactured by Instron Corporation, USA. Tensile tests were conducted on both double-crosslinked and chemically crosslinked samples to compare their mechanical properties. The clamp spacing was 10 mm, the tensile rate was 10 mm / min, and the specimen shape was dumbbell-shaped. Figure 12 As shown, A has a total length of 50mm, B has an end width of 8.5mm, C has a narrow section length of 16mm, D has a narrow section width of 4mm, E has an outer transition edge radius of 7.5mm, and F has an inner transition edge radius of 10mm.

[0069] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a double-crosslinked network material, characterized in that, The preparation method includes: (1) Keratin solution was contacted and reacted with aldehyde-modified dextran aqueous solution to obtain a preliminary cross-linked network; (2) The preliminary cross-linked network and dopamine solution are mixed and kept warm to obtain a double cross-linked network material.

2. The preparation method according to claim 1, wherein, In step (1), the keratin solution is prepared by the following method: dissolving keratin powder in PBS buffer to obtain the keratin solution, wherein the ratio of keratin powder to PBS buffer is 1:(4-6) g / mL; The pH of the PBS buffer is 8-10, and the concentration is 0.01-0.02 mol / L; The mass concentration of the aldehyde-modified dextran aqueous solution is 4%-10%.

3. The preparation method according to claim 1, wherein, In step (1), the keratin solution and the aldehyde-modified dextran aqueous solution are contacted and reacted at a mass ratio of 1:(1-5). The reaction is carried out at a temperature of 25-40℃ for 2-5 hours.

4. The preparation method according to claim 1, wherein, In step (1), the keratin is derived from hair, which is animal hair, preferably at least one of wool, human hair and feathers.

5. The preparation method according to claim 4, wherein, Keratin is obtained by a method comprising the following steps: pretreating the hair, and then extracting and purifying the pretreated hair by a reduction method to obtain the keratin.

6. The preparation method according to claim 5, wherein, The pretreatment includes: soaking the hair in an aqueous solution of sodium dodecyl sulfate, then washing it with water until neutral, and finally drying and cutting it into pieces; wherein the mass fraction of the aqueous solution of sodium dodecyl sulfate is 1%-2%; the soaking time is 1-3 hours; and the hair is cut into pieces to 1-2 mm. The reduction extraction method includes: mixing pretreated hair, Tris-HCl buffer, and β-mercaptoethanol, and reacting them to obtain a reaction solution containing keratin; wherein, in the reduction extraction method, the pH of the Tris-HCl buffer is 7-9, and the concentration is 0.1-0.2 mol / L; the ratio of pretreated hair to Tris-HCl buffer is 1:(15-25) g / mL; the amount of β-mercaptoethanol added is 5%-10% of the mass of the pretreated hair; the reaction temperature is 50-60℃, and the time is 4-6 h; The purification process includes: centrifuging the reaction solution containing keratin and collecting the supernatant; then precipitating the supernatant with alcohol, centrifuging to collect the precipitate; redissolving the precipitate with water and dialyzing; finally, freeze-drying the dialysate to obtain keratin; wherein, the alcohol precipitation uses anhydrous ethanol, and the volume ratio of anhydrous ethanol to supernatant is 1:(2-4); the dialysis uses a dialysis bag, and the dialysis bag has a molecular weight cutoff of 8000-14000 Da.

7. The preparation method according to claim 1, wherein, Aldehyde-modified dextran is prepared by a method comprising the following steps: placing an aqueous dextran solution in a light-proof container, adding sodium periodate, and stirring the reaction; then adding ethylene glycol to the reaction solution to terminate the reaction; next, placing the mixture obtained after terminating the reaction into a dialysis bag and dialyzing with water; finally, freeze-drying the dialysate to obtain the aldehyde-modified dextran. The dextran aqueous solution has a mass concentration of 4%-10%; the molecular weight of the dextran used is 50,000-100,000 Da; the molar ratio of dextran to sodium periodate is 1:(0.5-2); and the stirring reaction time is 2-3 h.

8. The preparation method according to claim 1, wherein, In step (2), the dopamine solution is prepared by the following steps: dissolving dopamine hydrochloride in PBS buffer to obtain a dopamine solution; the pH of the PBS buffer is 7-9 and the concentration is 0.01-0.02 mol / L; The mass of dopamine hydrochloride added is 5%-20% of the total mass of keratin and aldehyde-modified dextran; Keep warm at 25-37℃ for 1-2 hours.

9. A double cross-linked network material prepared by the preparation method according to any one of claims 1-8.

10. The application of the double cross-linked network material of claim 9 as a biomedical dressing or tissue engineering scaffold.

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