A modified silk fiber and its preparation and application

Abstract

The present invention belongs to the technical field of fiber material preparation and specifically discloses a modified silk fiber, its preparation, and application. The modified silk fiber has modified sericin and modified fibroin fixed to its surface. The silk fiber is preliminarily trimmed with a sericin fixative solution, and then the preliminarily trimmed silk fiber is grafted onto the modified solution. The modified solution contains cecropin antimicrobial peptide, tyrosinase, and carbodiimide. The modified silk fiber produced by the present invention has excellent antibacterial, moisturizing, skin-friendly, and skin-protecting properties. Fabrics produced using the modified silk fiber provided by the present invention have antibacterial durability, are less likely to harden after long-term use, and have excellent warmth retention.

Description

Technical Field

[0001] The present application relates to the technical field of fiber material preparation, and in particular to a modified silk fiber and its preparation and application. Background Art

[0002] Silk, one of the earliest natural proteins used by humans, possesses high strength and excellent elasticity. Its excellent moisture absorption, soft feel, gorgeous appearance, and elegant luster make it a popular choice among consumers, earning it the nickname "the Queen of Fibers." Silk is primarily composed of two main proteins: fibroin (approximately 70-75% by weight) and sericin (approximately 25-30% by weight).

[0003] Since silk is a pure natural animal protein, the antibacterial effect of processed silk is poor. Therefore, in humid and high temperature conditions, textiles using silk as raw material or main material tend to rot quickly and emit odor, resulting in a poor user experience of silk textiles, limiting the scope of use of silk textiles and increasing the difficulty of maintaining silk textiles. Existing silk fabrics have limited antibacterial effects, and silk fabrics tend to harden after long-term use, which reduces the warmth retention effect.

[0004] Sericin is a naturally occurring macromolecular protein encapsulating the surface of silk fibers. Secreted primarily by the silk glands of silkworms, it is one of the primary proteins in the silk cocoon. Due to its excellent water solubility, its ability to promote cell adhesion and proliferation, its reduced immunogenicity, and its unique in situ fluorescence, antioxidant activity, and tyrosinase inhibition, sericin is widely used in textile finishing coatings, cosmetic additives, as well as in food, pharmaceuticals, and functional biomaterials.

[0005] Sericin has good affinity, as well as excellent moisture retention, antibacterial, mildew-proof, and antistatic properties. It can enhance the properties of textiles made from silk fibers. However, sericin is easily soluble in water. Therefore, if silk fiber products, especially silk quilts, are exposed to moisture and not dried in time, they are prone to hardening, resulting in a decrease in the warmth-retaining effect of the silk quilt. Taking all factors into consideration, in the prior art, the silk used to make silk textiles or quilts needs to undergo a degumming process to remove most of the sericin on the silk surface to ensure the normal use of the silk fibers. However, this process reduces the utilization rate of the silk cocoons and significantly reduces the moisture retention, antibacterial, and antistatic properties of the resulting textiles.

[0006] In the existing technology, it is necessary to process silk fibers to improve the antibacterial effect, strength and other properties of silk fibers so that the silk fibers can be used effectively for a long time. The improvement of the antibacterial properties of silk fibers mainly includes fixing the antibacterial agent on the surface of silk fibers through reactive resins, fixing the antibacterial agent on the surface of silk fibers through adsorption, and fixing the antibacterial agent through two components that react with each other. However, on the one hand, the commonly used antibacterial agents have problems such as poor washing resistance and poor safety. On the other hand, the effect of silk having good affinity with the human body is reduced.

[0007] Therefore, in order to solve the above problems, it is necessary to make full use of sericin to modify silk fibers and improve the antibacterial and moisturizing properties of silk fibers.

[0008] Existing research provides antimicrobial modified silk fibers and a preparation method thereof. The preparation method includes preparing silk fibers, fixing sericin, preparing modified sericin, preparing an antimicrobial modifier, initially treating the silk fibers, and performing antimicrobial modification on the silk fibers. During the preparation process, urea is first used as an auxiliary agent and glutaraldehyde as a cross-linking agent to react with sericin, thereby reducing the degradation of sericin and thereby enhancing the antimicrobial ability of the silk protein. This reduces the water solubility of the sericin, thereby fixing the sericin on the surface of the silk fibers and preventing further dissolution and detachment of the sericin on the surface of the silk fibers during subsequent treatment. The silk fibers are then treated with an organosilicon emulsion containing emulsified sericin to enhance the hydrophobicity and softness of the silk fibers, and as a further protective agent, to impart good washability to the silk fibers. Finally, the silk fibers are treated with antimicrobial modification to impart good washability, hydrophilicity, and moisture retention to the antimicrobial modified fibers. However, this preparation method is complex and inefficient, and requires multiple components such as nanosilver. The process control is cumbersome and the economic cost is high, making it unsuitable for industrial production.

[0009] Currently, chemical modification is the most commonly used method for silk modification, but it is usually accompanied by problems such as harm to the human body or environmental pollution.

[0010] Enzymes are highly efficient, specific, and require mild reaction conditions for biocatalysts. Their processes are energy-efficient and environmentally friendly, making them widely used in the textile industry. Tyrosinase, a polyphenol oxidase, is widely present in nature. Because it effectively catalyzes the production of polyphenols and influences disease resistance and antioxidant properties, research is using tyrosinase as a precursor to modifying silk from a low-carbon and environmentally friendly perspective.

[0011] For example, existing research also provides an antibacterial temperature-controlling nanofiber, its preparation method, and application, belonging to the field of fiber material preparation technology. This invention uses tyrosinase and cecropin antimicrobial peptide to modify and graft sericin, which already has antimicrobial properties, further enhancing the sericin's antimicrobial properties. Tyrosinase and cecropin are biomaterials that are non-toxic, environmentally friendly, and highly compatible with sericin, allowing them to be well dispersed in a sericin solution to improve its antimicrobial properties. Furthermore, the modified sericin solution is mixed with N-isopropylacrylamide, N,N-methylenebisacrylamide, ammonium persulfate, N,N,N,N-tetramethylethylenediamine, and acetic acid, and subjected to free radical polymerization to produce nanofibers that also possess temperature-controlling properties. However, this method extracts sericin from silk fibers and modifies them to produce new fibers, without considering modifying the sericin while retaining it in the silk fibers.

[0012] Therefore, if a modified silk fiber and a preparation method thereof can be provided, which can fix sericin in the silk fiber and chemically modify the sericin and fibroin at the same time, and the method is simple and easy to control, it will be more conducive to the development of silk fiber, obtain antibacterial, moisturizing, skin care and other properties, and be conducive to large-scale industrial production. Summary of the Invention

[0013] In view of the above-mentioned shortcomings of the prior art, the present invention provides a modified silk fiber and its preparation and application to solve the problems in the prior art that the antibacterial effect of silk fabrics is limited, and the silk fabrics are prone to hardening after long-term use, resulting in a decrease in the warmth retention effect; the silk fiber modification method is complex, the process flow is cumbersome, and it is not conducive to industrial production.

[0014] To achieve the above-mentioned and related objectives, the present invention provides, in a first aspect, a modified silk fiber, wherein modified sericin and modified fibroin are fixed on the surface of the modified silk fiber. The silk fiber is preliminarily trimmed with a sericin fixing liquid, and then the preliminarily trimmed silk fiber is grafted onto the modifying liquid, wherein the modifying liquid contains cecropin antimicrobial peptide, tyrosinase and carbodiimide.

[0015] In one embodiment of the present application, the sericin fixing solution contains glutaraldehyde and urea.

[0016] A second aspect of the present invention provides a method for preparing modified silk fibers, the method comprising the following steps:

[0017] (1) Fixation of sericin: Glutaraldehyde and urea are prepared to obtain a sericin fixative, and the pretreated silk fibers are immersed in the sericin fixative;

[0018] (2) Preparation of a modified solution: tyrosinase, cecropin antimicrobial peptide, and carbodiimide are mixed to obtain a modified solution;

[0019] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 60 to 130 minutes, and a grafting reaction is performed for 1 to 2.5 hours to obtain a modified silk fiber.

[0020] In one embodiment of the present application, in step (1), the mass concentration of glutaraldehyde is 0.5% to 1%, the mass concentration of urea is 0.5% to 2%, the temperature of the sericin fixative is adjusted to 45 to 60° C., and the immersion treatment is performed for 6 to 24 hours.

[0021] In one embodiment of the present application, the concentration of tyrosinase in step (2) is 5-7 U / mL, and the mass concentration of cecropin is 5-8 g / L.

[0022] In one embodiment of the present application, the carbodiimide in step (2) is any one of N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0023] In one embodiment of the present application, the mass concentration of carbodiimide in step (2) is 1-5 g / L.

[0024] In one embodiment of the present application, the pH of the enzyme-catalyzed oxidation reaction and grafting reaction in step (3) is 6.5-8.5, and the reaction temperature is 25-45°C.

[0025] In one embodiment of the present application, the modification solution in step (2) further includes a phosphate buffer solution of N-hydroxysuccinimide.

[0026] In one embodiment of the present application, the pretreatment of the silk fibers in step (1) includes degreasing the silk fibers, and after degreasing, scouring the silk fibers once with a 5 g / L sodium carbonate solution.

[0027] The third aspect of the present invention provides the use of the modified silk fiber as described above or the modified silk fiber prepared by the method for preparing the modified silk fiber as described above in single yarn and fabric.

[0028] The beneficial technical effects of the present invention are:

[0029] Antimicrobial peptides are a class of small, antimicrobial peptides widely found in living organisms, forming part of their defense system. Most of these active peptides possess strong alkalinity, thermal stability, and broad-spectrum antibacterial and antiviral properties. Their mechanism of action differs from that of antibiotics. Some antimicrobial peptides bind to cell membranes through electrostatic interactions, altering the membrane structure. The amino acid residues interact with the negatively charged phospholipids in the cell membrane, forming transmembrane pores or transient cavities, which can cause cell death. Consequently, they exhibit selective toxicity, high efficacy, physical and chemical stability, and resistance to drug resistance. Attaching antimicrobial peptide molecules to biomaterials can prevent the development of drug resistance and ensure long-lasting, stable antimicrobial properties on the biomaterial surface.

[0030] Cecropins are a class of small molecule proteins with antibacterial properties produced by plants and animals. They are currently the best-studied and most effective antimicrobial peptides. Cecropins have strong inhibitory effects against both Gram-negative and Gram-positive bacteria, Escherichia coli, Salmonella, and Staphylococcus aureus. Cecropins have five structures: A, B, C, D, and E. Cecropin B has stronger antibacterial and antiviral effects. Therefore, the present invention uses cecropins for modification of silk fibers, with cecropin B being the preferred structure.

[0031] Because sericin is coated on the surface of fibroin, the present invention first pre-treats the silk fibers to remove impurities such as oil from the surface. The silk fibers are then scoured once with sodium carbonate to remove some of the sericin, exposing the fibroin for chemical reactions. By controlling the amount of sodium carbonate used and the number of scouring times, some sericin remains on the surface of the silk fibers.

[0032] The present invention uses glutaraldehyde as a cross-linking agent and urea as an auxiliary agent to fix sericin remaining on the surface of silk fibers, and after fixation, the glutaraldehyde and urea attached to the surface of the silk fibers are washed away.

[0033] The present invention uses tyrosinase, cecropin, and carbodiimide to prepare a modification solution that simultaneously grafts sericin and fibroin on the surface of silk fibers. When the silk fibers are immersed in the modification solution, the sericin on the surface undergoes an enzymatic oxidation reaction with the tyrosinase, generating sericin quinone, which is then grafted onto the cecropin, further enhancing the sericin's antimicrobial properties. Furthermore, tyrosinase and cecropin are biomaterials, non-toxic, and environmentally friendly, with good compatibility with sericin. They can be well dispersed in the sericin to improve its antimicrobial properties.

[0034] At the same time, the silk fibroin on the surface of the silk fiber undergoes a grafting reaction with the cecropin antimicrobial peptide under the action of carbodiimide, and the peptide bond can be connected to the surface of the silk fibroin, which improves the hydrophilicity of the silk fibroin, reduces the contact angle, and enhances the antibacterial property. Specifically, the silk fibroin molecule contains a certain amount of side chains, and the side chains contain amino acid residues with carboxyl groups. Carbodiimide, as a condensing agent, can react with the carboxyl groups on the side chains of the silk fibroin molecule to form an acylurea intermediate with amino-reactive activity. The addition of N-hydroxysuccinimide (NHS) phosphate buffer converts the intermediate into an NHS ester with amino-reactive activity, which can react with the amino group in the cecropin antimicrobial peptide molecule, thereby connecting the peptide bond to the surface of the silk fibroin. In addition, carbodiimide can also form a catalyst with 4-dimethylaminopyridine, which is conducive to catalyzing the grafting reaction between sericin and cecropin antimicrobial peptide.

[0035] In summary, the modified silk fibers produced by the present invention have excellent antibacterial, moisturizing, skin-friendly, and skin-protecting properties. Fabrics produced using the modified silk fibers provided by the present invention have antibacterial and durable properties, are not prone to hardening after long-term use, have good warmth retention, and have good antiviral effects. The preparation method of the modified silk fibers of the present invention is simple, easy to control, and suitable for industrial production. DETAILED DESCRIPTION

[0036] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as generally understood by those of ordinary skill in the art to which the present invention belongs. It should be understood that some features of the present invention (for clarity, described in the environment of separate embodiments) may also be provided in combination in a single embodiment. On the contrary, a plurality of features of the present invention (for brevity, described in the environment of a single embodiment) may also be provided separately or in any suitable combination or in any other described embodiment of the present invention when suitable. Some features described in the environment of various embodiments will not be considered as essential features of those embodiments, unless the embodiment is inoperable without those elements. The present invention will be further described below by specific specific examples, but it should be noted that the specific blending ratio, process conditions and results described in the embodiments of the present invention are only used to illustrate the present invention, and cannot limit the scope of protection of the present invention with this. All equivalent changes or modifications made according to the spirit and essence of the present invention should be included in the scope of protection of the present invention.

[0037] The present invention provides a method for preparing modified silk fiber, which comprises the following steps:

[0038] (1) Fixation of sericin: Glutaraldehyde with a mass concentration of 0.5% to 1% is used as a cross-linking agent, and urea with a mass concentration of 0.5% to 2% is used as an auxiliary agent to prepare a sericin fixative solution. The temperature of the sericin fixative solution is adjusted to 45 to 60°C, and the pretreated silk fibers are immersed in the sericin fixative solution for 6 to 24 hours. The pretreatment includes degreasing the silk fibers. After degreasing, the silk fibers are scoured once with a 5 g / L sodium carbonate solution.

[0039] After the impregnation is completed, the silk fibers are taken out and rinsed with 50°C deionized water to remove glutaraldehyde and urea attached to the surface of the silk fibers, and then dehydrated and dried to complete the fixation of the sericin.

[0040] (2) Preparation of the modification solution: tyrosinase with a concentration of 5 to 7 U / mL, cecropin antimicrobial peptide with a mass concentration of 5 to 8 g / L, and carbodiimide with a mass concentration of 1 to 5 g / L are mixed to obtain a modification solution, wherein the carbodiimide is any one of N,Nˊ-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; the modification solution also includes 4-dimethylaminopyridine with a mass concentration of 1 to 3 g / L and a phosphate buffer solution of N-hydroxysuccinimide, and the molar ratio of N-hydroxysuccinimide to carbodiimide is 1:1.

[0041] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 60 to 130 minutes, and a grafting reaction is performed for 1 to 2.5 hours. The pH of the enzyme-catalyzed oxidation reaction and the grafting reaction is 6.5 to 8.5, and the reaction temperature is 25 to 45° C. to obtain a modified silk fiber.

[0042] In the present invention, the phenolic hydroxyl groups of sericin are oxidized to quinones by tyrosinase to form a sericin quinone solution. The quinones in the sericin quinone solution undergo a grafting reaction with the amino groups in the cecropin antimicrobial peptide. During the reaction, the cecropin antimicrobial peptide is grafted onto the sericin molecules, thereby obtaining modified silk fibers.

[0043] The present invention selects the reaction conditions of tyrosinase by the following determination method:

[0044] Take a certain amount of 90fxg / mL L-tyrosine and add it to 0.1M phosphate buffer with a pH of 6.5. After keeping the temperature in a 35℃ water bath for 10 minutes, add tyrosinase solution, mix well, incubate at 35℃ for 30 minutes, quickly transfer to a cuvette, and measure the absorbance at 475nm.

[0045] Positive control: Take 0.01 g of arbutin powder and dissolve it in 20 ml of methanol solution to obtain a 0.5 mg / mL reference solution. Quickly transfer it to a cuvette and measure the absorbance at 475 nm.

[0046] According to the measured structure, the optimal reaction conditions of tyrosinase were selected as follows: tyrosinase concentration of 5-7 U / mL, the reaction conditions of enzyme-catalyzed oxidation reaction and grafting reaction were consistent, reaction temperature of 25-45°C, pH of 6.5-8.5, more preferably, tyrosinase concentration of 6 U / mL, reaction temperature of enzyme-catalyzed oxidation reaction and grafting reaction of 35°C, pH of 6.8.

[0047] The present invention also provides a modified silk fiber, wherein modified sericin and modified fibroin are fixed on the surface of the modified silk fiber. The silk fiber is preliminarily trimmed with a sericin fixing liquid, and then the preliminarily trimmed silk fiber is grafted with the modifying liquid to obtain the modified silk fiber. The modifying liquid contains cecropin antimicrobial peptide, tyrosinase and carbodiimide.

[0048] The present invention also provides the use of the modified silk fiber as described above or the modified silk fiber prepared by the preparation method of the modified silk fiber as described above in single yarn and fabric.

[0049] The present invention is described in detail below by way of specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not to be limited to the specific numerical values ​​exemplified below.

[0050] Example 1

[0051] (1) Fixation of sericin: Glutaraldehyde with a mass concentration of 0.5% was used as a cross-linking agent, and urea with a mass concentration of 0.5% was used as an auxiliary agent to prepare a sericin fixative. The temperature of the sericin fixative was adjusted to 45°C, and the pretreated silk fibers were immersed in the sericin fixative for 16 hours. The pretreatment included degreasing the silk fibers. After degreasing, the silk fibers were scoured once with a 5 g / L sodium carbonate solution.

[0052] After the impregnation is completed, the silk fibers are taken out and rinsed with 50°C deionized water to remove glutaraldehyde and urea attached to the surface of the silk fibers, and then dehydrated and dried to complete the fixation of the sericin.

[0053] (2) Preparation of modification solution: tyrosinase with a concentration of 5 U / mL, cecropin antimicrobial peptide B with a mass concentration of 5 g / L, N,N'-dicyclohexylcarbodiimide with a mass concentration of 2 g / L, 4-dimethylaminopyridine with a mass concentration of 1 g / L, and N-hydroxysuccinimide phosphate buffer with a molar ratio of N-hydroxysuccinimide to carbodiimide of 1:1 were mixed to obtain a modification solution;

[0054] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 120 minutes, and a grafting reaction is performed for 2 hours. The pH of the enzyme-catalyzed oxidation reaction and the grafting reaction is 6.5, and the reaction temperature is 25° C., to obtain a modified silk fiber.

[0055] Example 2

[0056] (1) Fixation of sericin: Glutaraldehyde with a mass concentration of 0.8% was used as a cross-linking agent, and urea with a mass concentration of 1% was used as an auxiliary agent to prepare a sericin fixative. The temperature of the sericin fixative was adjusted to 50°C, and the pretreated silk fibers were immersed in the sericin fixative for 12 hours. The pretreatment included degreasing the silk fibers. After degreasing, the silk fibers were scoured once with a 5 g / L sodium carbonate solution.

[0057] After the impregnation is completed, the silk fibers are taken out and rinsed with 50°C deionized water to remove glutaraldehyde and urea attached to the surface of the silk fibers, and then dehydrated and dried to complete the fixation of the sericin.

[0058] (2) Preparation of modification solution: tyrosinase with a tyrosinase concentration of 6 U / mL, cecropin antimicrobial peptide B with a mass concentration of 6 g / L, N,N'-dicyclohexylcarbodiimide with a mass concentration of 2 g / L, 4-dimethylaminopyridine with a mass concentration of 1 g / L, and N-hydroxysuccinimide phosphate buffer with a molar ratio of N-hydroxysuccinimide to carbodiimide of 1:1 were mixed to obtain a modification solution;

[0059] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 60 minutes, and a grafting reaction is performed for 1 hour. The pH of the enzyme-catalyzed oxidation reaction and the grafting reaction is 6.8, and the reaction temperature is 35° C., to obtain a modified silk fiber.

[0060] Example 3

[0061] (1) Fixation of sericin: Glutaraldehyde with a mass concentration of 1% was used as a cross-linking agent, and urea with a mass concentration of 1.5% was used as an auxiliary agent to prepare a sericin fixative. The temperature of the sericin fixative was adjusted to 55°C, and the pretreated silk fibers were immersed in the sericin fixative for 10 hours. The pretreatment included degreasing the silk fibers. After degreasing, the silk fibers were scoured once with a 5g / L sodium carbonate solution.

[0062] After the impregnation is completed, the silk fibers are taken out and rinsed with 50°C deionized water to remove glutaraldehyde and urea attached to the surface of the silk fibers, and then dehydrated and dried to complete the fixation of the sericin.

[0063] (2) Preparation of modification solution: tyrosinase with a tyrosinase concentration of 6 U / mL, cecropin antimicrobial peptide B with a mass concentration of 8 g / L, N,N'-dicyclohexylcarbodiimide with a mass concentration of 2 g / L, 4-dimethylaminopyridine with a mass concentration of 1 g / L, and N-hydroxysuccinimide phosphate buffer with a molar ratio of N-hydroxysuccinimide to carbodiimide of 1:1 were mixed to obtain a modification solution;

[0064] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 90 minutes, and a grafting reaction is performed for 1.5 hours. The pH of the enzyme-catalyzed oxidation reaction and the grafting reaction is 7.5, and the reaction temperature is 30° C. to obtain a modified silk fiber.

[0065] Example 4

[0066] (1) Fixation of sericin: Glutaraldehyde with a mass concentration of 1% was used as a cross-linking agent, and urea with a mass concentration of 2% was used as an auxiliary agent to prepare a sericin fixative. The temperature of the sericin fixative was adjusted to 60°C, and the pretreated silk fibers were immersed in the sericin fixative for 12 hours. The pretreatment included degreasing the silk fibers. After degreasing, the silk fibers were scoured once with a 5 g / L sodium carbonate solution.

[0067] After the impregnation is completed, the silk fibers are taken out and rinsed with 50°C deionized water to remove glutaraldehyde and urea attached to the surface of the silk fibers, and then dehydrated and dried to complete the fixation of the sericin.

[0068] (2) Preparation of modification solution: 8 U / mL tyrosinase, 8 g / L cecropin antimicrobial peptide B, 2 g / L N,N'-dicyclohexylcarbodiimide, 1 g / L 4-dimethylaminopyridine, and a phosphate buffered saline solution containing N-hydroxysuccinimide and carbodiimide at a molar ratio of 1:1 were mixed to obtain a modification solution;

[0069] (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 130 minutes, and a grafting reaction is performed for 2 hours. The pH of the enzyme-catalyzed oxidation reaction and the grafting reaction is 8, and the reaction temperature is 40° C., to obtain a modified silk fiber.

[0070] Comparative Example 1

[0071] The raw silk is immersed in warm water at 60° C. for 24 hours, the moisture of the raw silk is gently shaken off, and then immersed in a medical-grade acidic glutaraldehyde solution with a mass concentration of 1.5% at a bath ratio of 1 g:100 mL for 3 hours, the immersed raw silk is dehydrated, washed with tap water, and soaked for 24 hours, wherein the tap water is changed three times, and then dehydrated, dried, or air-dried to obtain the treated silk;

[0072] The silk was sequentially placed in a sodium carbonate aqueous solution with a mass concentration of 0.3% at a bath ratio of 1g:50mL, and treated three times at 98-100°C, with the first two treatments lasting 30min and the third treatment lasting 45min. After treatment, the silk was soaked in tap water, washed, and dried to obtain modified silk fibers.

[0073] Comparative Example 2

[0074] Silk fibers were scoured three times with 5 g / L sodium carbonate solution to remove sericin and other impurities on the surface of the silk fibers, each time for 30 min at 98°C and a bath ratio of 1:100. The fibers were then washed and dried, immersed in phosphate buffer (0.1 mol / L Na2HPO4, 0.5 mol / L NaCl, pH 6.5) for 30 min, and then immersed in 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) / N-hydroxysuccinimide (NHS) solution (0.5 mg / mL EDC, 0.7 mg / mL NHS in phosphate buffer) at room temperature for 15 min. The silk fibers were rinsed with phosphate buffer and then reacted with antimicrobial peptide (0.1 mg / mL) dissolved in phosphate buffer at room temperature for 2 h. The reacted silk fibers were then immersed in phosphate buffer for 5 min, rinsed twice with phosphate buffer, and rinsed once with deionized water, and dried to obtain modified silk fibers.

[0075] Performance Testing

[0076] Antibacterial property: According to GB / T20944.3-2008 “Evaluation of antibacterial properties of textiles - Part 3: Oscillation method”, the antibacterial properties of modified silk fibers against Staphylococcus aureus ATCC6538, Escherichia coli 8099 and Candida albicans ATCC10231 before and after treatment were determined by the oscillation flask method.

[0077] The silk fibers modified in Examples 1-4 and Comparative Examples 1-2 were tested for antibacterial activity, with the results recorded as the initial inhibition rate. The modified silk fibers were then washed as follows: soaked in a 20% sodium stearate solution at 25°C for 5 minutes, rinsed five times with clean water, and dried. The modified silk fibers were washed 10 and 20 times. The antibacterial test results are shown in Tables 1 and 2.

[0078] Antiviral effect: Referring to ISO 18184-2019 Determination of antiviral activity of textiles, the modified silk fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were washed 20 times and the antiviral test results are shown in Table 3.

[0079] Table 1 Antibacterial test results of modified silk fibers in various embodiments and comparative examples

[0080]

[0081]

[0082] Table 2 Antibacterial test results of modified silk fibers in various embodiments and comparative examples

[0083]

[0084] (Note: The antibacterial rate against Staphylococcus aureus and Escherichia coli is ≥70%, and the antibacterial rate against Candida albicans is ≥60%. The sample has antibacterial effect)

[0085] As shown in Table 1, after 20 washes, the antibacterial rates of the modified silk fiber in Example 2 were 92.41% (Staphylococcus aureus) and 93.76% (Escherichia coli), respectively. Compared with their initial antibacterial rates, the antibacterial rates decreased by 5.46% and 5.07%, respectively. After 20 washes, the antibacterial rates of the modified silk fiber in Comparative Example 1 decreased by 11.36% and 11.44%, respectively, compared with their initial antibacterial rates. After 20 washes, the antibacterial rates of the modified silk fiber in Comparative Example 2 decreased by 10.04% and 9.25%, respectively, compared with their initial antibacterial rates.

[0086] As shown in Table 2, after 20 washes, the antibacterial rate of the modified silk fiber in Example 2 against Candida albicans was 91.64%, which was 5.96% lower than its initial antibacterial rate. However, after 20 washes, the antibacterial rate of the modified silk fiber in Comparative Example 1 was 13.18% lower than its initial antibacterial rate, and after 20 washes, the antibacterial rate of the modified silk fiber in Comparative Example 2 was 10.71% lower than its initial antibacterial rate.

[0087] Comparison of Examples 1-4 with Comparative Examples 1-2 demonstrates that the silk fibers modified using the present invention exhibit excellent wash fastness and antimicrobial durability. The modified silk fibers of Comparative Example 1 merely have sericin fixed to the surface of the silk fibers without further antimicrobial treatment. Therefore, while they exhibit good water absorption and retention, their antimicrobial durability is poor. The modified silk fibers of Comparative Example 2 undergo degumming, where only the fibroin is modified with antimicrobial peptides without further enhancing its antimicrobial durability using sericin. Furthermore, the modified silk fibers of Comparative Example 2 exhibit poor moisture retention. The modification method of the present invention effectively fixes sericin on the surface of silk fibers, imparting excellent water absorption and moisture retention to the silk fibers. Furthermore, the modification solution simultaneously modifies sericin and fibroin, allowing the grafting of cecropin B, further enhancing the antimicrobial durability of the silk fibers. Cecropin B exhibits excellent thermal stability and strong antimicrobial activity, effectively inhibiting the growth of both Gram-negative and Gram-positive bacteria, and can also inhibit and kill Candida albicans, while remaining non-toxic to human cell lines. Consequently, when fabrics are made from the modified silk fibers prepared by the modification method of the present invention, the sericin, under the action of the fabric, exhibits skin-friendly, skin-protecting, and moisturizing properties. The fabrics are less likely to become clumped after prolonged use, exhibiting excellent warmth retention, and, through the combined action of cecropin B, exhibit excellent antimicrobial durability, safety, and environmental protection.

[0088] Table 3 Antiviral activity values ​​of modified silk fibers in various examples and comparative examples

[0089] Initial antiviral activity value Antiviral activity value after 20 washes Example 1 3.45 3.40 Example 2 3.62 3.59 Example 3 3.55 3.51 Example 4 3.37 3.32 Comparative Example 1 2.32 1.77 Comparative Example 2 3.18 2.88

[0090] As shown in Table 3, the antiviral effect of the modified silk fibers prepared in Examples 1 to 4 of the present invention after 20 washes is not much different from the initial antiviral effect, with the maximum decrease being only 1.44%. However, the antiviral effect of the modified silk fibers prepared in Comparative Examples 1 and 2 decreased significantly after 20 washes, with Comparative Example 1 decreasing by 23.71% and Comparative Example 2 decreasing by 9.43%. This shows that the modified silk fibers prepared in the present invention have the best antiviral effect during long-term use.

[0091] In summary, the modified silk fibers prepared by the modification method of the present invention exhibit excellent antibacterial, moisturizing, skin-friendly, and skin-protecting properties. Fabrics made using the modified silk fibers provided by the present invention exhibit antibacterial and durable properties, are less susceptible to hardening after long-term use, and exhibit excellent warmth retention and antiviral effects. The preparation method of the modified silk fibers of the present invention is simple, easy to control, and suitable for industrial production.

[0092] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing modified silk fiber, characterized in that: The method comprises the following steps: (1) Fixation of sericin: glutaraldehyde and urea are prepared to obtain a sericin fixative, and the pretreated silk fibers are immersed in the sericin fixative; (2) Preparation of a modification solution: tyrosinase, cecropin antimicrobial peptide, and carbodiimide are mixed to obtain a modification solution, wherein the concentration of tyrosinase in the modification solution is 5-7 U / mL, the mass concentration of cecropin antimicrobial peptide is 5-8 g / L, and the mass concentration of carbodiimide is 1-5 g / L. The carbodiimide is any one of N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride. The modification solution also includes a phosphate buffer solution of N-hydroxysuccinimide. (3) Under the protection of an oxygen atmosphere, the silk fiber immobilized with sericin in step (1) is immersed in the modification solution in step (2), and an enzyme-catalyzed oxidation reaction is performed for 60 to 130 minutes, and a grafting reaction is performed for 1 to 2.5 hours to obtain a modified silk fiber.

2. The method for preparing modified silk fiber according to claim 1, wherein: In step (1), the mass concentration of glutaraldehyde is 0.5% to 1%, the mass concentration of urea is 0.5% to 2%, the temperature of the sericin fixative is adjusted to 45 to 60° C., and the immersion treatment is performed for 6 to 24 hours.

3. The method for preparing modified silk fiber according to claim 1, wherein: The pH of the enzyme-catalyzed oxidation reaction and grafting reaction in step (3) is 6.5-8.5, and the reaction temperature is 25-45°C.

4. The method for preparing modified silk fiber according to claim 1, wherein: The pretreatment of the silk fibers in step (1) includes degreasing the silk fibers, and after degreasing, scouring the silk fibers once with a 5 g / L sodium carbonate solution.

5. A modified silk fiber prepared according to the method according to any one of claims 1 to 4.

6. Use of the modified silk fiber prepared by the method for preparing the modified silk fiber according to any one of claims 1 to 4 in textiles.

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