Preparation method of keratin bio-based temperature-sensitive polymer

Abstract

The invention provides a preparation method of a keratin bio-based temperature-sensitive material, which comprises the following steps: extracting keratin in hair by adopting a reduction method to obtain keratin molecules containing active groups; the keratin bio-based temperature-sensitive material is prepared from active keratin molecules and an N-isopropylacrylamide monomer (NIPAm) through a one-step polymerization method. Compared with an existing two-step method for preparing a temperature-sensitive polymer material, the method has the advantages that the bio-based temperature-sensitive material is prepared through a one-step method by means of the structural advantages of keratin macromolecules, and the method has the advantages of being simple in synthesis process step, free of an accelerant and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature-sensitive materials, and in particular to a keratin bio-based temperature-sensitive polymer material and a preparation method thereof. Background Art

[0002] Keratin, as a natural polymer material, is widely found in animal hair, nails, horns, and feathers. It is not only rich in sources and low in price, but also has good biocompatibility, biodegradability, and low immune rejection. At present, keratin and its products have broad development space and huge application value in the fields of biomedical materials, drug sustained-release materials, and daily materials. my country's wool textile industry and animal husbandry produce a large amount of discarded animal hair fibers every year, and the keratin content is as high as 90%. However, natural hair fibers are difficult to degrade under natural conditions due to their stable structure, and their arbitrary discarding will cause great environmental pollution. Therefore, if the discarded natural keratin fibers are developed and utilized, it can not only achieve the reuse of discarded protein resources, but also reduce environmental pollution, and have huge economic and social benefits.

[0003] In recent years, bio-based thermosensitive polymers have been widely used in biomedical fields such as controlled drug release, bioseparation, enzyme immobilization, and immunoassay. Bio-based thermosensitive polymers are usually prepared by a two-step method. The first step is to perform specific grouping during the NIPAm polymerization process, and the second step is to graft polymerize the reactive groups introduced in the first step with the natural polymer to achieve thermosensitive modification of the natural polymer material. The above two-step method for modifying natural polymer materials is relatively cumbersome. In comparison, keratin can be extracted by selecting a specific method to make the resulting keratin macromolecules have natural reactive groups, thereby providing feasibility for the one-step preparation of natural macromolecular bio-based thermosensitive polymers. Summary of the invention

[0004] The purpose of the present invention is to provide a one-step method for preparing a keratin bio-based thermosensitive polymer, which improves the complex process of first polymerization and then grafting to modify the thermosensitive biopolymer in a two-step method.

[0005] In order to achieve the above object, the present invention provides a method for preparing a keratin bio-based temperature-sensitive polymer, comprising the following steps:

[0006] S1. A keratin aqueous solution having a concentration of 1.5-2%, a potassium persulfate (KPS) aqueous solution having a concentration of 6-7%, and an N-isopropylacrylamide monomer (NIPAm) aqueous solution having a concentration of 20-25% are prepared respectively;

[0007] S2. The keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution were mixed in a volume ratio of 30:1-30:10, and stirred at 60° C. for 0.5-1 h to obtain a uniformly mixed keratin / N-isopropylacrylamide monomer (NIPAm) aqueous solution;

[0008] S3. Using a one-step synthesis method, a keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution and a potassium persulfate aqueous solution were mixed in a volume ratio of 5:1, and the mixture was stirred for 1-3 hours until the solution turned milky white to obtain a keratin bio-based thermosensitive polymer solution;

[0009] S4. The keratin bio-based thermosensitive polymer solution is dialyzed and freeze-dried for 16-24 hours to obtain keratin bio-based thermosensitive polymer powder.

[0010] The present invention adopts a one-step method to synthesize a keratin bio-based thermosensitive polymer, extracts keratin with a preferred reducing agent to obtain active keratin macromolecules, and in an aqueous phase system, uses the active thiol groups on the keratin molecules as a synthetic reaction promoter to participate in the polymerization reaction of thermosensitive monomers to achieve a one-step synthesis of a keratin bio-based thermosensitive polymer. Compared with the prior art method of modifying a natural polymer with a thermosensitive polymer by a two-step synthesis, the process flow is shortened by half, the efficiency is significantly improved, and the method has broad application prospects in the preparation field of keratin bio-based thermosensitive polymers.

[0011] Furthermore, the natural keratin fiber is human hair, wool, rabbit hair, cow hair, pig hair or camel hair.

[0012] Furthermore, the keratin is prepared by the following steps:

[0013] S11. The natural keratin fibers were opened and cut into 5-10 mm long fiber segments after impurities were removed, and then washed with petroleum ether solvent for about 40 min to remove impurities, and then washed with distilled water 4-5 times and dried naturally at room temperature;

[0014] S12. The natural keratin fiber is immersed in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 8-12g / 120ml, stirred at a temperature of 60-70°C for 4-6h, and the stirrer speed is 150-300r / min;

[0015] S13. The mixture obtained after stirring was filtered through a 100-150 mesh sieve to remove undissolved natural keratin fibers, and the filtered keratin salt solution was dialyzed at room temperature using a dialysis bag with a molecular weight cutoff of 8000-14000Da to remove salt and small molecules in the solution. The dialysis time was 36-72h, and the distilled water was changed every 12h;

[0016] S14. The dialyzed keratin was centrifuged to remove the precipitate in the dialysate at a centrifugal speed of 5000-7000 rpm for 0.25 hO.5 h, and then the supernatant was taken;

[0017] S15. The supernatant is concentrated to obtain a keratin concentrated solution having a keratin concentration of 10-14% by mass;

[0018] S16. freeze-dry the keratin concentrated solution for 24-36 hours to obtain keratin powder.

[0019] Furthermore, the reducing agent is 2-mercaptoethanol (also known as β-mercaptoethanol), tri(2-carboxyethyl)phosphine (TCEP), dithiothreitol, thioglycolic acid, sodium sulfide, etc., and the mass percentage concentration of the reducing agent is 1%-3%. The surfactant is sodium dodecyl sulfate, and the mass percentage concentration of the surfactant is 2%-4%.

[0020] Furthermore, the one-step synthesis method is an aqueous phase organic synthesis, and the reactants include active keratin molecules, an initiator and N-isopropylacrylamide monomers. In the aqueous phase system, the active thiol groups on the keratin molecules act as synthesis reaction promoters, and participate in the polymerization reaction of the thermosensitive monomers to achieve the one-step synthesis of keratin bio-based thermosensitive polymers.

[0021] By adopting the above technical solution, the present invention has the following beneficial effects:

[0022] The present invention provides a method for preparing a keratin-based thermosensitive polymer, which adopts a one-step synthesis method, obtains active keratin macromolecules by preferably adding a reducing agent in an aqueous phase system, and uses the active thiol groups on the macromolecules as a synthetic reaction promoter to participate in the polymerization reaction of the thermosensitive monomer, thereby realizing the one-step synthesis of keratin bio-based thermosensitive polymers. Compared with the prior art method of modifying natural polymers with thermosensitive polymers by two-step synthesis, the process flow is shortened by half, the efficiency is significantly improved, and it has broad application prospects in the preparation field of keratin bio-based thermosensitive polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is the nuclear magnetic resonance hydrogen spectrum of active keratin RFK.

[0025] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of isopropylacrylamide NIPAm.

[0026] Figure 3 This is the nuclear magnetic resonance hydrogen spectrum of keratin bio-based thermosensitive polymer P (NIPAm-RFK).

[0027] Figure 4 Fourier infrared spectra of active keratin RFK, isopropyl acrylamide PNIPAm and keratin bio-based thermosensitive polymer P (NIPAm-RFK).

[0028] Figure 5 This is the LCST value diagram of keratin bio-based thermosensitive polymer P (NIPAm-RFK).

[0029] Figure 6 This is the effect diagram of keratin bio-based thermosensitive polymer P (NIPAm-RFK) before and after phase change. DETAILED DESCRIPTION

[0030] The present invention is further explained below in conjunction with specific implementation methods; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment discloses a method for preparing a human hair keratin bio-based temperature-sensitive polymer, comprising the following steps:

[0033] (1) The human hair fibers were opened and cleaned, and then cut into fiber segments of 5-10 mm in length, and then washed with petroleum ether solvent for about 40 minutes to remove impurities, and then repeatedly washed with distilled water for 4-5 times, and then naturally dried at room temperature;

[0034] (2) immersing in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 8 g / 120 ml, stirring at 65° C. for 4 h, with a stirrer speed of 160 r / min;

[0035] The reducing agent is 2-mercaptoethanol (also known as β-mercaptoethanol), and its mass percentage concentration is 1.8% of the mixed solution; the surfactant is sodium dodecyl sulfate, and its mass percentage concentration is 2.5% of the mixed solution.

[0036] (3) filtering the mixture obtained after stirring through a 100-mesh sieve to remove undissolved human hair fibers, and dialyzing the filtered keratin salt solution using a dialysis bag with a molecular weight cutoff of 8000-14000Da at room temperature to remove salt and small molecules in the solution. The dialysis time is 48 hours, and the distilled water is replaced every 12 hours;

[0037] (4) centrifuging the dialyzed human hair keratin to remove the precipitate in the dialysate at a centrifugal speed of 6000 rpm for 0.3 h, and then taking the supernatant;

[0038] (5) concentrating the supernatant to obtain a human hair keratin concentrated solution having a keratin mass percentage concentration of 12%;

[0039] (6) freeze-drying the concentrated human hair keratin solution for 24 hours to obtain human hair keratin powder.

[0040] (7) preparing a 1.8% aqueous solution of human keratin, a 6.6% aqueous solution of potassium persulfate (KPS), and a 24% aqueous solution of N-isopropylacrylamide monomer (NIPAm);

[0041] (8) Mixing the human hair keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution in a volume ratio of 30:6, stirring at 60° C. for 0.5-1 h, and obtaining a uniformly mixed human hair keratin solution.

[0042] / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution;

[0043] (9) A one-step synthesis method was used to mix a human hair keratin / N-isopropylacrylamide monomer (NIPAm) aqueous solution with a potassium persulfate aqueous solution in a volume ratio of 5:1, and the mixture was stirred for 1-3 hours until the solution turned milky white to obtain a keratin bio-based thermosensitive polymer solution;

[0044] (10) The human hair keratin bio-based thermosensitive polymer solution is dialyzed and then freeze-dried for 16-24 hours to obtain a human hair keratin bio-based thermosensitive polymer powder.

[0045] Example 2

[0046] This embodiment discloses a method for preparing a wool keratin bio-based temperature-sensitive polymer, comprising the following steps:

[0047] (1) The wool fibers are opened and cleaned, and then cut into fiber segments of 5-10 mm in length, and then washed with acetone solvent for about 40 minutes to remove impurities, and then repeatedly washed with distilled water for 4-5 times, and then dried naturally at room temperature;

[0048] (2) immersing in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 12 g / 120 ml, stirring at 60° C. for 5 h, with a stirrer speed of 180 r / min;

[0049] The reducing agent is dithiothreitol, and the mass percentage concentration is 1.5% of the mixed solution; the surfactant is sodium dodecyl sulfate, and the mass percentage concentration is 2% of the mixed solution.

[0050] (3) filtering the mixture obtained after stirring through a 120-mesh sieve to remove undissolved human hair fibers, and dialyzing the filtered keratin salt solution using a dialysis bag with a molecular weight cutoff of 8000-14000Da at room temperature to remove salt and small molecules in the solution. The dialysis time is 36 hours, and the distilled water is replaced every 12 hours;

[0051] (4) centrifuging the dialyzed wool keratin to remove the precipitate in the dialysate at a centrifugal speed of 5000 rpm for 0.4 h, and then taking the supernatant;

[0052] (5) concentrating the supernatant to obtain a wool keratin concentrated solution having a keratin mass percentage concentration of 14%;

[0053] (6) Freeze-drying the wool keratin concentrated solution for 36 hours to obtain wool keratin powder.

[0054] (7) preparing a 1.7% wool keratin aqueous solution, a 6.2% potassium persulfate (KPS) aqueous solution, and a 22% N-isopropylacrylamide monomer (NIPAm) aqueous solution respectively;

[0055] (8) mixing the wool keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution in a volume ratio of 30:3, stirring at 60° C. for 0.5-1 h to obtain a uniformly mixed wool keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution;

[0056] (9) A one-step synthesis method was used to mix a wool keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution with a potassium persulfate aqueous solution in a volume ratio of 5:1, and the mixture was stirred for 1-3 hours until the solution turned milky white to obtain a wool keratin bio-based thermosensitive polymer solution;

[0057] (10) The human hair keratin bio-based thermosensitive polymer solution is dialyzed and then freeze-dried for 16-24 hours to obtain a human hair keratin bio-based thermosensitive polymer powder.

[0058] Example 3

[0059] This embodiment discloses a method for preparing a rabbit hair keratin bio-based temperature-sensitive polymer, comprising the following steps:

[0060] (1) The rabbit hair fibers are opened and cleaned, and then cut into fiber segments of 5-10 mm in length, and then washed with anhydrous ethanol solvent for about 40 minutes to remove impurities, and then repeatedly washed with distilled water for 4-5 times, and then naturally dried at room temperature;

[0061] (2) immersing in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 10 g / 120 ml, stirring at 70° C. for 4 h, with a stirrer speed of 200 r / min;

[0062] The reducing agent is tri(2-carboxyethyl)phosphine (TCEP), and its mass percentage concentration is 2% of the mixed solution; the surfactant is sodium dodecyl sulfate, and its mass percentage concentration is 3.5% of the mixed solution.

[0063] (3) The mixture obtained after stirring was filtered through a 150-mesh sieve to remove undissolved human hair fibers, and the filtered keratin salt solution was dialyzed using a dialysis bag with a molecular weight cutoff of 8000-14000Da at room temperature to remove salt and small molecules in the solution. The dialysis time was 72 hours, and the distilled water was replaced every 12 hours:

[0064] (4) centrifuging the dialyzed rabbit hair keratin to remove the precipitate in the dialysate at a centrifugal speed of 6500 rpm for 0.25 h, and then taking the supernatant;

[0065] (5) concentrating the supernatant to obtain a rabbit hair keratin concentrated solution having a keratin mass percentage concentration of 10%;

[0066] (6) freeze-drying the rabbit hair keratin concentrated solution for 30 hours to obtain rabbit hair keratin powder.

[0067] (7) preparing a 1.5% rabbit hair keratin aqueous solution, a 6% potassium persulfate (KPS) aqueous solution, and a 20% N-isopropylacrylamide monomer (NIPAm) aqueous solution respectively;

[0068] (8) mixing the rabbit hair keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution in a volume ratio of 30:1, stirring at 60° C. for 0.5-1 h to obtain a uniformly mixed keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution;

[0069] (9) Using a one-step synthesis method, a rabbit hair keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution was mixed with a potassium persulfate aqueous solution in a volume ratio of 5:1, and stirring was continued for 1-3 hours until the solution turned milky white to obtain a rabbit hair keratin bio-based thermosensitive polymer solution;

[0070] (10) The rabbit hair keratin bio-based thermosensitive polymer solution is dialyzed and then freeze-dried for 16-24 hours to obtain rabbit hair keratin bio-based thermosensitive polymer powder.

[0071] Example 4

[0072] This embodiment discloses a method for preparing a porcine keratin bio-based temperature-sensitive polymer, comprising the following steps:

[0073] (1) Opening and removing impurities from pig hair fibers, cutting them into fiber segments of 5-10 mm in length, then washing them with petroleum ether solvent for about 40 minutes to remove impurities, repeatedly washing them with distilled water for 4-5 times, and then drying them naturally at room temperature;

[0074] (2) immersing in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 10 g / 120 ml, stirring at 60° C. for 6 h, with a stirrer speed of 300 r / min;

[0075] The reducing agent is sodium sulfide, and its mass percentage concentration is 3% of the mixed solution; the surfactant is sodium dodecyl sulfate, and its mass percentage concentration is 4% of the mixed solution.

[0076] (3) filtering the mixture obtained after stirring through a 140-mesh sieve to remove undissolved human hair fibers, and dialyzing the filtered keratin salt solution using a dialysis bag with a molecular weight cutoff of 8000-14000Da at room temperature to remove salt and small molecules in the solution. The dialysis time is 60 hours, and the distilled water is replaced every 12 hours;

[0077] (4) centrifuging the dialyzed porcine keratin to remove the precipitate in the dialysate at a centrifugal speed of 7000 rpm for 0.5 h, and then taking the supernatant;

[0078] (5) concentrating the supernatant to obtain a pig hair keratin concentrated solution having a keratin mass percentage concentration of 14%;

[0079] (6) Freeze-drying the pig hair keratin concentrated solution for 30 hours to obtain pig hair keratin powder.

[0080] (7) respectively preparing a 2% aqueous solution of pig hair keratin, a 7% aqueous solution of potassium persulfate (KPS), and a 25% aqueous solution of N-isopropylacrylamide monomer (NIPAm);

[0081] (8) mixing the pig hair keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution in a volume ratio of 30:10, stirring at 60° C. for 0.5-1 h to obtain a uniformly mixed pig hair keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution;

[0082] (9) Using a one-step synthesis method, a pig hair keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution was mixed with a potassium persulfate aqueous solution in a volume ratio of 5:1, and stirring was continued for 1-3 hours until the solution turned milky white to obtain a pig hair keratin bio-based thermosensitive polymer solution;

[0083] (10) The pig hair keratin bio-based thermosensitive polymer solution is dialyzed and then freeze-dried for 16-24 hours to obtain a pig hair keratin bio-based thermosensitive polymer powder.

Claims

1. A method for preparing a keratin bio-based thermosensitive polymer, characterized in that: The steps include: S1. A keratin aqueous solution having a concentration of 1.5-2%, a potassium persulfate (KPS) aqueous solution having a concentration of 6-7%, and an N-isopropylacrylamide monomer (NIPAm) aqueous solution having a concentration of 20-25% are prepared respectively; S2. The keratin aqueous solution and the N-isopropylacrylamide monomer (NIPAm) aqueous solution were mixed in a volume ratio of 30:1-30:10, and stirred at 60° C. for 0.5-1 h to obtain a uniformly mixed keratin / N-isopropylacrylamide monomer (NIPAm) aqueous solution; S3. Using a one-step synthesis method, a keratin / N-isopropylacrylamide monomer (NIPAm) blended aqueous solution and a potassium persulfate aqueous solution were mixed in a volume ratio of 5:1, and the mixture was stirred for 1-3 hours until the solution turned milky white to obtain a keratin bio-based thermosensitive polymer solution; S4. The keratin bio-based thermosensitive polymer solution is dialyzed and freeze-dried for 16-24 hours to obtain keratin bio-based thermosensitive polymer powder.

2. The method for preparing a keratin bio-based thermosensitive polymer according to claim 1, characterized in that: The natural keratin fiber is human hair, wool, rabbit hair, cow hair, pig hair or camel hair.

3. The method for preparing a keratin bio-based thermosensitive polymer according to claim 1, characterized in that: The keratin is prepared by the following steps: S11. The natural keratin fibers were opened and cut into 5-10 mm long fiber segments after impurities were removed, and then washed with petroleum ether solvent for about 40 min to remove impurities, and then washed with distilled water 4-5 times and dried naturally at room temperature; S12. The natural keratin fiber is immersed in a mixed solution containing a reducing agent and a surfactant at a solid-liquid ratio of 8-12g / 120ml, stirred at a temperature of 60-70°C for 4-6h, and the stirrer speed is 150-300r / min; S13. The mixture obtained after stirring was filtered through a 100-150 mesh sieve to remove undissolved natural keratin fibers, and the filtered keratin salt solution was dialyzed at room temperature using a dialysis bag with a molecular weight cutoff of 8000-14000Da to remove salt and small molecules in the solution. The dialysis time was 36-72h, and the distilled water was changed every 12h; S14. The dialyzed keratin was centrifuged to remove the precipitate in the dialysate at a centrifugal speed of 5000-7000 rpm for 0.25 hO.5 h, and then the supernatant was taken; S15. The supernatant is concentrated to obtain a keratin concentrated solution having a keratin concentration of 10-14% by mass; S16. Freeze-dry the keratin concentrated solution for 24-36 hours to obtain keratin powder.

4. The method for preparing the keratin bio-based thermosensitive polymer according to claim 1, characterized in that The reducing agent is 2-mercaptoethanol (also known as β-mercaptoethanol), tri(2-carboxyethyl)phosphine (TCEP), dithiothreitol, thioglycolic acid, sodium sulfide, etc., and the mass percentage concentration of the reducing agent is 1%-3%. The surfactant is sodium dodecyl sulfate, and the mass percentage concentration of the surfactant is 2%-4%.

5. The method for preparing the keratin bio-based thermosensitive polymer according to claim 1, characterized in that: The one-step synthesis method is an aqueous phase organic synthesis, and the reactants include active keratin molecules, an initiator and N-isopropylacrylamide monomers. In the aqueous phase system, the active thiol groups on the keratin molecules act as a synthesis reaction accelerator, and participate in the polymerization reaction of the thermosensitive monomers to achieve a one-step synthesis of keratin bio-based thermosensitive polymers.

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