A sericin protein in-situ reduction silver-loaded PET fiber and its preparation method and application

Abstract

The present invention discloses a sericin protein in-situ reduced silver-loaded PET fiber and its preparation method and application, which belongs to the technical field of fiber materials. Among them, the preparation method of the sericin protein in-situ reduced silver-loaded PET fiber includes the following steps: subjecting the PET fiber to oxygen plasma treatment to obtain an activated PET fiber rich in carboxyl groups; impregnating the activated PET fiber in a sericin protein solution for modification to obtain a graft-modified PET fiber; placing the graft-modified PET fiber in a silver nitrate solution, chelating silver ions on the surface of the PET fiber by using sericin protein, and using the reducing amino acids contained therein as a reducing agent to reduce the silver ions into silver nanoparticles through an in-situ reduction reaction to obtain the sericin protein in-situ reduced silver-loaded PET fiber. The sericin protein in-situ reduced silver-loaded PET fiber has persistent and excellent antibacterial properties, remarkable wettability and skin-friendly properties.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber materials, and specifically to a sericin protein in-situ reduction silver-loaded PET fiber, its preparation method and application. Background Art

[0002] Polyethylene terephthalate (PET) fiber is a common synthetic fiber, which is widely used in fields such as textiles and packaging materials. However, PET fiber has significant deficiencies in skin-friendly property and antibacterial property, which limits its use in some applications. Due to the lack of polar groups, such as carboxylic acid groups or hydroxyl groups, in the PET molecular structure, its surface has strong hydrophobicity and low hygroscopicity, which results in poor skin-friendly property of PET fiber. At the same time, this low hygroscopicity makes it impossible for PET fiber to effectively absorb and evaporate sweat when directly contacting the skin, thus causing the wearer to feel stuffy and uncomfortable. In addition, due to the poor air permeability of PET fiber, it is easy to form a humid and hot environment on the skin surface, providing favorable conditions for bacterial growth. People with sensitive skin are particularly vulnerable to irritation, showing allergic reactions such as itching and redness. At the same time, the antibacterial property of PET fiber is also relatively weak. Although the antibacterial property of PET fiber can be improved by physical or chemical modification methods, there are many problems. For example, by adding antibacterial agents on the surface, but these methods are often costly and the effect persistence is limited; the surface coating method has weak binding force and the antibacterial persistence needs to be improved; while the physical mixing method is simple, but the selection and addition amount of antibacterial components are limited, and too high antibacterial components will affect the intrinsic mechanical properties of the fiber, which results in unsatisfactory antibacterial effect of the fiber. In addition, the physical mixing method usually requires a high-temperature and long-time blending process, and PET may degrade during the high-temperature processing, affecting its antibacterial property.

[0003] As a new type of antibacterial agent, silver nanoparticles are widely used in the preparation of antibacterial materials due to their unique physical and chemical properties, such as high specific surface area, high electron affinity, and good biocompatibility. In the field of PET antibacterial, the introduction of silver nanoparticles can significantly improve the antibacterial performance of materials, thus playing an important role in fields such as medicine, food packaging, and textiles. Currently, most reported studies directly blend silver nanoparticles with PET or graft them onto the surface of PET fibers after modification. However, the high activity and nano-size effect of silver nanoparticles can cause them to easily agglomerate and cannot be uniformly dispersed on the surface and inside of PET, thereby affecting the antibacterial performance of the fibers. At the same time, for antibacterial PET obtained by blending, coating, or physical adsorption, the large release of silver nanoparticles due to weak binding may cause silver poisoning, etc., which has an adverse impact on human health and the natural world. Therefore, to solve the problems of easy agglomeration of silver nanoparticles, poor binding, and poor skin-friendly properties of PET fibers when compounded with PET, there is an urgent need to develop a new method for preparing PET fiber materials with both skin-friendly properties and long-term antibacterial performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing sericin in-situ reduced silver-loaded PET fibers to solve the problems raised in the above background technology.

[0005] To achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

[0006] A method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0007] Perform oxygen plasma treatment on PET fibers to obtain activated PET fibers rich in carboxyl groups;

[0008] Immerse the activated PET fibers in a sericin solution for modification to obtain graft-modified PET fibers;

[0009] Place the graft-modified PET fibers in a silver nitrate solution, chelate silver ions on the surface of the PET fibers using sericin, and use the reducing amino acids contained therein as reducing agents to reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0010] Preferably, the power of the oxygen plasma treatment is 10 - 300 W, and the time is 5 - 60 min.

[0011] Preferably, the step of immersing the activated PET fibers in a sericin solution for modification to obtain graft-modified PET fibers specifically includes:

[0012] The activated PET fibers are impregnated in a sericin solution, and a composite catalyst is used to form a firm amide covalent bond between the activated PET fibers and sericin through a catalytic cross-linking reaction to obtain graft-modified PET fibers; the composite catalyst is a composite system of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide; the mass ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to N-hydroxysuccinimide is (1.8-2.2):1.

[0013] Preferably, the sericin solution is an ethanol aqueous solution of sericin; the mass concentration of sericin in the ethanol aqueous solution is 1%-10%; the ethanol aqueous solution is composed of absolute ethanol and deionized water, and the volume ratio of absolute ethanol to deionized water is (8.5-9.5):(0.5-1.5).

[0014] Preferably, the pH value of the reaction system for the catalytic cross-linking reaction is 3-6, the reaction temperature is 1-10 °C, and the reaction time is 24-72 h.

[0015] Preferably, the mass-to-volume ratio of the activated PET fibers to the sericin solution is 1 kg:(30-100) L.

[0016] Preferably, the silver nitrate solution is an aqueous solution of silver nitrate, and its concentration is 50-100 mmol / L.

[0017] Preferably, the mass-to-volume ratio of the graft-modified PET fibers to the silver nitrate solution is 1 kg:(30-100) L.

[0018] Another object of the present invention is to provide a sericin in-situ reduction silver-loaded PET fiber prepared by the above preparation method, wherein the silver nanoparticles in the sericin in-situ reduction silver-loaded PET fiber are loaded on the surface of the graft-modified PET fiber through coordination chelation; the graft-modified PET fiber is a PET fiber in which sericin is combined by an amide covalent bond.

[0019] Another object of the present invention is to provide an application of the above sericin in-situ reduction silver-loaded PET fiber in the preparation of an antibacterial agent.

[0020] The preparation method of sericin in-situ reduced silver-loaded PET fiber provided by the present invention treats PET by oxygen plasma to obtain activated PET fiber rich in oxygen-containing active groups such as carboxyl groups, while improving the surface roughness and wettability of the fiber; then, the activated PET fiber is used as a carrier, and its surface microcavities and concave holes are used as anchor points, and through the action of a compound catalyst, sericin is modified onto the surface of the PET fiber to obtain a graft-modified PET fiber with covalent cross-linking of sericin; through coordination chelation, sericin binds silver ions in the silver nitrate solution to the PET fiber, and with the help of reducing amino acids such as tyrosine, aspartic acid, and glutamic acid contained in sericin as reducing agents, the silver ions are in-situ reduced to silver nanoparticles. The oxygen plasma-activated PET fiber has a large number of oxygen-containing polar groups such as carboxyl groups and hydroxyl groups. Sericin is firmly bound to the activated PET through amide covalent bonds, and silver nanoparticles are chelated, fixed, and green in-situ reduced and synthesized by using a three-dimensional porous structure. The preparation method provided by the present invention is green and environmentally friendly, and the sericin in-situ reduced silver-loaded PET fiber prepared by it has persistent and excellent antibacterial properties, remarkable wettability, and skin-friendly properties. Description of the Drawings

[0021] Figure 1 It is a scanning electron microscope image of the activated PET fiber treated by oxygen plasma; in the figure, (a). Scanning electron microscope image of the PET fiber before modification; (b). Scanning electron microscope image of the PET fiber treated by oxygen plasma.

[0022] Figure 2 It is a scanning electron microscope image of the sericin in-situ reduced silver-loaded PET fiber; in the figure, (a). Scanning electron microscope image of the sericin in-situ reduced silver-loaded PET fiber magnified 5000 times; (b). Scanning electron microscope image of the sericin in-situ reduced silver-loaded PET fiber magnified 10000 times.

[0023] Figure 3 It is the XRD pattern of the sericin in-situ reduced silver-loaded PET fiber.

[0024] Figure 4 It is the element distribution map of the sericin in-situ reduced silver-loaded PET fiber; in the figure, (a). Surface scanning electron microscope image of the element analysis of the sericin in-situ reduced silver-loaded PET fiber; (b). Element content distribution map of the sericin in-situ reduced silver-loaded PET fiber; (c). Distribution map of the elements contained in the sericin in-situ reduced silver-loaded PET fiber.

[0025] Figure 5 It is the infrared spectrum of the sericin in-situ reduced silver-loaded PET fiber.

[0026] Figure 6It is the antibacterial property qualitative test diagram of the sericin in-situ reduction silver-loaded PET fiber; in the figure, (a). The antibacterial property test diagram of the PET fiber before modification against Staphylococcus aureus; (b). The antibacterial property test diagram of the sericin in-situ reduction silver-loaded PET fiber against Staphylococcus aureus.

[0027] Figure 7 It is the moisture regain diagram of the sericin in-situ reduction silver-loaded PET fiber. Specific embodiments

[0028] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0029] In an embodiment of the present invention, a preparation method of a sericin in-situ reduction silver-loaded PET fiber is provided, which includes the following steps:

[0030] S1. Perform oxygen plasma treatment on the PET fiber to obtain an activated PET fiber rich in carboxyl groups;

[0031] S2. Immerse the activated PET fiber in a sericin solution for modification to obtain a graft-modified PET fiber;

[0032] S3. Place the graft-modified PET fiber in a silver nitrate solution, chelate silver ions on the surface of the PET fiber by sericin, and use the reducing amino acids contained therein as a reducing agent to reduce the silver ions into silver nanoparticles through an in-situ reduction reaction to obtain a sericin in-situ reduction silver-loaded PET fiber.

[0033] In the sericin in-situ reduction silver-loaded PET fiber prepared in the embodiment of the present invention, the silver nanoparticles are loaded on the surface of the graft-modified PET fiber through coordination chelation; the above graft-modified PET fiber is a PET fiber in which sericin is combined by an amide covalent bond.

[0034] In a preferred embodiment of the present invention, the power of the oxygen plasma treatment is 10 - 300 W, and the time is 5 - 60 min.

[0035] In a preferred embodiment of the present invention, the step of immersing the activated PET fiber in a sericin solution for modification to obtain a graft-modified PET fiber specifically includes:

[0036] The activated PET fibers are impregnated in a sericin solution, and a composite catalyst is used to form a firm amide covalent bond between the activated PET fibers and sericin through a catalytic cross-linking reaction, obtaining graft-modified PET fibers; the composite catalyst is a composite system of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide; the mass ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to N-hydroxysuccinimide is (1.8-2.2):1, preferably 2:1.

[0037] In a preferred embodiment of the present invention, the sericin solution is an ethanol aqueous solution of sericin; the mass concentration of sericin in the ethanol aqueous solution is 1%-10%; the ethanol aqueous solution is composed of absolute ethanol and deionized water, and the volume ratio of absolute ethanol to deionized water is (8.5-9.5):(0.5-1.5), preferably 9:1.

[0038] In a preferred embodiment of the present invention, the pH value of the reaction system for the catalytic cross-linking reaction is 3-6, the reaction temperature is 1-10 °C, and the reaction time is 24-72 h.

[0039] In a preferred embodiment of the present invention, the mass-volume ratio (bath ratio) of the activated PET fibers to the sericin solution is 1 kg:(30-100) L.

[0040] In a preferred embodiment of the present invention, the silver nitrate solution is an aqueous solution of silver nitrate, and its concentration is 50-100 mmol / L.

[0041] In a preferred embodiment of the present invention, the mass-volume ratio (bath ratio) of the graft-modified PET fibers to the silver nitrate solution is 1 kg:(30-100) L.

[0042] In another embodiment of the present invention, there is also provided an application of the above sericin in-situ reduction silver-loaded PET fibers in the antibacterial field; as a reducing agent and a dispersant, sericin in-situ reduces silver ions on the surface of PET fibers into silver nanoparticles and binds them to the surface of PET fibers through coordination chelation, which enables the silver nanoparticles to be uniformly and firmly bound to the surface of PET fibers, and the PET fibers have persistent antibacterial properties. At the same time, sericin has excellent skin-friendly and moisture-absorbing properties, endowing the PET fibers with high-efficiency and excellent antibacterial properties, remarkable wettability and skin-friendly properties. The sericin in-situ reduction silver-loaded PET fibers have excellent and long-lasting antibacterial effects and excellent antibacterial wash resistance.

[0043] Specifically, the technical solutions provided by the embodiments of the present invention have the following beneficial effects:

[0044] (1) Activated PET fibers were obtained by oxygen plasma treatment, which improved the surface roughness and wettability of the fibers. Sericin was firmly bound to the activated PET through amide covalent bonds. Utilizing the natural affinity and three-dimensional structure of sericin, it provided a stable carrier for silver nanoparticles, which not only helped prevent the aggregation of metal particles but also improved the efficiency of catalytic reduction. Finally, with the help of reducing amino acids such as tyrosine, aspartic acid, and glutamic acid contained in sericin as reducing agents, silver ions on the surface of PET fibers were in-situ reduced to silver nanoparticles. At the same time, sericin has excellent skin-friendly and hygroscopic properties, endowing PET fibers with high-efficiency and excellent antibacterial properties, remarkable wettability, and skin-friendly properties.

[0045] (2) As a reducing agent and dispersant, sericin in-situ reduced silver ions on the surface of PET fibers to silver nanoparticles and bound them to the surface of PET fibers through coordination chelation, which enabled the silver nanoparticles to be uniformly and firmly bound to the surface of PET fibers, and the PET fibers had persistent antibacterial properties.

[0046] (3) The sericin in-situ reduced silver-loaded PET fibers prepared in the examples of the present invention can be applied in the antibacterial field, and at the same time, the synthesis technology of the silver-containing antibacterial agent in PET fibers is green and environmentally friendly. The sericin in-situ reduced silver-loaded PET fibers have excellent and long-lasting antibacterial effects, excellent antibacterial wash resistance, and have great application prospects in the field of functional antibacterial textiles.

[0047] The following examples are some specific implementation cases of the present invention in actual applications, but are not limited thereto.

[0048] Example 1: This example provides a preparation method of sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0049] S1. The PET fibers were subjected to oxygen plasma treatment with a power of 100 W and a time of 15 min to obtain activated PET fibers rich in carboxyl groups;

[0050] S2. The obtained activated PET fibers were impregnated in an ethanol aqueous solution of sericin with a mass concentration of 5% at a bath ratio of 1 kg:50 L. The ethanol aqueous solution was composed of anhydrous ethanol and deionized water in a volume ratio of 9:1, and a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 2:1 was added for reaction. Through catalytic cross-linking reaction, the activated PET fibers and sericin formed firm amide covalent bonds to obtain graft-modified PET fibers; during the reaction process, the pH value of the reaction system was adjusted with morpholineethanesulfonic acid monohydrate, and the pH value of the reaction system for catalytic cross-linking reaction was 5, the reaction temperature was 4 °C, and the reaction time was 24 h;

[0051] S3. Immerse the graft-modified PET fibers in an aqueous solution of silver nitrate at 80 mmol / L according to a bath ratio of 1 kg:90 L for reaction. Chelate silver ions on the surface of PET fibers using sericin, and use the reducing amino acids contained therein as reducing agents. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 9, reaction temperature = 70 °C, and reaction time = 5 h. Reduce silver ions to silver nanoparticles through in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0052] Example 2: This example provides a method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0053] S1. Perform oxygen plasma treatment on PET fibers. The power of oxygen plasma treatment is 200 W and the time is 10 min to obtain activated PET fibers rich in carboxyl groups.

[0054] S2. Immerse the obtained activated PET fibers in an aqueous ethanol solution of sericin with a mass concentration of 8% according to a bath ratio of 1 kg:70 L. The aqueous ethanol solution is composed of absolute ethanol and deionized water according to a volume ratio of 9:1, and add a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide according to a mass ratio of 2:1 for reaction. Through catalytic cross-linking reaction, form amide covalent bonds between the activated PET fibers and sericin to firmly combine and obtain graft-modified PET fibers. During the reaction process, adjust the pH value of the reaction system with morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for catalytic cross-linking reaction is 3, the reaction temperature is 9 °C, and the reaction time is 36 h.

[0055] S3. Immerse the graft-modified PET fibers in an aqueous solution of silver nitrate at 60 mmol / L according to a bath ratio of 1 kg:60 L for reaction. Chelate silver ions on the surface of PET fibers using sericin, and use the reducing amino acids contained therein as reducing agents. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 8, reaction temperature = 80 °C, and reaction time = 8 h. Reduce silver ions to silver nanoparticles through in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0056] Example 3: This example provides a method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0057] S1. Perform oxygen plasma treatment on PET fibers. The power of oxygen plasma treatment is 300 W and the time is 5 min to obtain activated PET fibers rich in carboxyl groups.

[0058] S2. Immerse the obtained activated PET fibers in an aqueous ethanol solution of sericin protein with a mass concentration of 10% at a bath ratio of 1 kg:100 L. The aqueous ethanol solution is composed of absolute ethanol and deionized water at a volume ratio of 9:1, and a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide at a mass ratio of 2:1 is added for reaction. Through the catalytic cross-linking reaction, the activated PET fibers and sericin protein form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, the pH value of the reaction system is adjusted by morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for the catalytic cross-linking reaction is 6, the reaction temperature is 10 °C, and the reaction time is 72 h.

[0059] S3. Place the graft-modified PET fibers in an aqueous solution of 100 mmol / L silver nitrate at a bath ratio of 1 kg:100 L for reaction. Chelate silver ions on the surface of the PET fibers by sericin protein, and use the reducing amino acids contained in it as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 12, reaction temperature is 60 °C, and reaction time is 10 h. Reduce silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin protein in-situ reduced silver-loaded PET fibers.

[0060] Example 4: This example provides a preparation method of sericin protein in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0061] S1. Perform oxygen plasma treatment on PET fibers. The power of the oxygen plasma treatment is 10 W and the time is 60 min to obtain activated PET fibers rich in carboxyl groups.

[0062] S2. Immerse the obtained activated PET fibers in an aqueous ethanol solution of sericin protein with a mass concentration of 3% at a bath ratio of 1 kg:(50 - 100) L. The aqueous ethanol solution is composed of absolute ethanol and deionized water at a volume ratio of 9:1, and a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide at a mass ratio of 2:1 is added for reaction. Through the catalytic cross-linking reaction, the activated PET fibers and sericin protein form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, the pH value of the reaction system is adjusted by morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for the catalytic cross-linking reaction is 3, the reaction temperature is 2 °C, and the reaction time is 70 h.

[0063] S3. Place the graft-modified PET fibers in an aqueous solution of 90 mmol / L silver nitrate at a bath ratio of 1 kg:70 L for reaction. Use sericin to chelate silver ions on the surface of the PET fibers, and use the reducing amino acids it contains as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 11, reaction temperature = 65 °C, and reaction time = 9 h. Reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0064] Example 5: This example provides a method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0065] S1. Perform oxygen plasma treatment on the PET fibers. The power of the oxygen plasma treatment is 150 W and the time is 50 min to obtain activated PET fibers rich in carboxyl groups.

[0066] S2. Immerse the obtained activated PET fibers in an ethanol aqueous solution of sericin with a mass concentration of 7% at a bath ratio of 1 kg:80 L. The ethanol aqueous solution is composed of absolute ethanol and deionized water in a volume ratio of 9:1, and add a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 2:1 for reaction. Through catalytic cross-linking reaction, the activated PET fibers and sericin form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, use morpholineethanesulfonic acid monohydrate to adjust the pH value of the reaction system. The pH value of the reaction system for the catalytic cross-linking reaction is 5, the reaction temperature is 7 °C, and the reaction time is 30 h.

[0067] S3. Place the graft-modified PET fibers in an aqueous solution of 75 mmol / L silver nitrate at a bath ratio of 1 kg:30 L for reaction. Use sericin to chelate silver ions on the surface of the PET fibers, and use the reducing amino acids it contains as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 12, reaction temperature = 75 °C, and reaction time = 8.5 h. Reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0068] Example 6: This example provides a method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0069] S1. Perform oxygen plasma treatment on the PET fibers. The power of the oxygen plasma treatment is 90 W and the time is 52 min to obtain activated PET fibers rich in carboxyl groups.

[0070] S2. Immerse the obtained activated PET fibers in an aqueous ethanol solution of sericin protein with a mass concentration of 7.2 - 5% at a bath ratio of 1 kg:30 L. The aqueous ethanol solution is composed of absolute ethanol and deionized water in a volume ratio of 9:1, and a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 2:1 is added for reaction. Through the catalytic cross-linking reaction, the activated PET fibers and sericin protein form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, the pH value of the reaction system is adjusted with morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for the catalytic cross-linking reaction is 4, the reaction temperature is 7 °C, and the reaction time is 24 h.

[0071] S3. Place the graft-modified PET fibers in an aqueous solution of 95 mmol / L silver nitrate at a bath ratio of 1 kg:85 L for reaction. Chelate silver ions on the surface of the PET fibers with sericin protein, and use the reducing amino acids contained in it as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 10, the reaction temperature is 64 °C, and the reaction time is 9.5 h. Reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin protein in-situ reduced silver-loaded PET fibers.

[0072] Example 7: This example provides a method for preparing sericin protein in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0073] S1. Perform oxygen plasma treatment on the PET fibers. The power of the oxygen plasma treatment is 10 W and the time is 60 min to obtain activated PET fibers rich in carboxyl groups.

[0074] S2. Immerse the obtained activated PET fibers in an aqueous ethanol solution of sericin protein with a mass concentration of 1% at a bath ratio of 1 kg:50 L. The aqueous ethanol solution is composed of absolute ethanol and deionized water in a volume ratio of 8.5:1.5, and a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 1.8:1 is added for reaction. Through the catalytic cross-linking reaction, the activated PET fibers and sericin protein form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, the pH value of the reaction system is adjusted with morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for the catalytic cross-linking reaction is 3, the reaction temperature is 1 °C, and the reaction time is 24 h.

[0075] S3. Place the graft-modified PET fibers in an aqueous solution of 50 mmol / L silver nitrate at a bath ratio of 1 kg:50 L for reaction. Chelate silver ions on the surface of the PET fibers using sericin, and use the reducing amino acids contained therein as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 9, reaction temperature = 70 °C, and reaction time = 5 h. Reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0076] Example 8: This example provides a method for preparing sericin in-situ reduced silver-loaded PET fibers, which includes the following steps:

[0077] S1. Perform oxygen plasma treatment on the PET fibers. The power of the oxygen plasma treatment is 300 W and the time is 5 min to obtain activated PET fibers rich in carboxyl groups.

[0078] S2. Immerse the obtained activated PET fibers in an ethanol aqueous solution of 10% sericin at a bath ratio of 1 kg:100 L. The ethanol aqueous solution is composed of absolute ethanol and deionized water at a volume ratio of 9.5:0.5, and add a compound catalyst composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide at a mass ratio of 2.2:1 for reaction. Through catalytic cross-linking reaction, the activated PET fibers and sericin form a firm amide covalent bond to obtain graft-modified PET fibers. During the reaction process, adjust the pH value of the reaction system with morpholineethanesulfonic acid monohydrate. The pH value of the reaction system for the catalytic cross-linking reaction is 6, the reaction temperature is 10 °C, and the reaction time is 72 h.

[0079] S3. Place the graft-modified PET fibers in an aqueous solution of 100 mmol / L silver nitrate at a bath ratio of 1 kg:100 L for reaction. Chelate silver ions on the surface of the PET fibers using sericin, and use the reducing amino acids contained therein as a reducing agent. Adjust the pH value of the solution with sodium hydroxide. The reaction conditions are pH = 9, reaction temperature = 70 °C, and reaction time = 5 h. Reduce the silver ions to silver nanoparticles through an in-situ reduction reaction to obtain sericin in-situ reduced silver-loaded PET fibers.

[0080] Performance test: Taking the sericin in-situ reduced silver-loaded PET fibers prepared in Example 1 above as an example, conduct relevant performance research and analysis, and the results are as Figures 1 - 7 and Table 1 shows.

[0081] Among them, Figure 1 is the scanning electron microscope image of the activated PET fibers treated by oxygen plasma. From Figure 1As can be seen from (a), the surface of the untreated PET fiber sample is relatively smooth; while Figure 1 (b) shows that obvious concave holes and microcavities appear on the surface of the polyester fiber after plasma treatment, and the surface roughness increases significantly. This change is attributed to the impact of high-energy particles in the plasma, including the etching effect caused by the bombardment of positive and negative ions and neutral particles. During this process, the macromolecular chemical bonds on the fiber surface are broken, and then react with free radicals in the plasma to generate oxygen-containing groups, thereby changing the chemical properties and morphological characteristics of the fiber surface. In order to confirm the successful synthesis of sericin in-situ reduced silver-loaded PET fibers, scanning electron microscopy was used to analyze the microscopic morphology of the fibers.

[0082] Figure 2 It is the scanning electron microscopy image of sericin in-situ reduced silver-loaded PET fibers, Figure 2 (a) and (b) are scanning electron microscopy images at different magnifications. Sericin is firmly bound to the activated PET through amide covalent bonds. Using the natural affinity and three-dimensional structure of sericin, it provides a stable carrier for silver nanoparticles, which not only helps to prevent the aggregation of metal particles, but also improves the efficiency of catalytic reduction. Finally, with the help of reducing amino acids such as tyrosine, aspartic acid and glutamic acid contained in sericin as reducing agents, silver ions on the surface of PET fibers are in-situ reduced to silver nanoparticles. The silver nanoparticles have regular morphology and uniform size. At the same time, it can be seen that the silver nanoparticles are evenly and firmly bound to the surface of PET fibers. This is mainly because the coordination chelation of oxygen-containing groups in sericin binds to Ag + Combined, as a reducing agent and dispersant, sericin can in-situ reduce silver ions on the surface of PET fibers to silver nanoparticles and bind them to the surface of PET fibers through coordination chelation, which enables the silver nanoparticles to be evenly and firmly bound to the surface of PET fibers, providing a basis for the high-performance and long-lasting antibacterial properties of PET fibers.

[0083] In order to confirm the existence of silver nanoparticles, X-ray diffractometer was used to analyze the crystal types of the PET fibers before modification and the sericin in-situ reduced silver-loaded PET fibers. The results are as Figure 3 shown. By analyzing the XRD pattern of the PET fibers before modification, it was found that the broad peak at 2θ = 22.09° belongs to the original PET fibers. After modifying the PET fibers with AgNPs, in the XRD pattern, four diffraction peaks were observed at 2θ = 34.76°, 44.17°, 65.53°, 77.07°, corresponding to the (111), (200), (220), (311) reflections of the face-centered cubic (fcc) structure of metallic silver, respectively. Therefore, it can be clearly seen that the silver nanoparticles on the surface of PET fibers are crystalline.

[0084] To illustrate that silver nanoparticles are uniformly and firmly loaded on the PET surface, the experiment used an energy dispersive spectrometer to analyze the element distribution and content of the fiber, and the results are as Figure 4 shown. Figure 4 It is the element distribution map of the sericin in-situ reduced silver-loaded PET fiber. Figure 4 (a) in Figure 4 is the surface scanning electron microscope image of the element analysis of the sericin in-situ reduced silver-loaded PET fiber. It can be seen from the figure that silver nanoparticles are uniformly and firmly loaded on the surface of the PET fiber. Figure 4 (b) in Figure 4 is the element content distribution map of the fiber. It can be seen from the figure that the Ag content can reach 16 Wt%, which indicates that the sericin in-situ reduced silver-loaded PET fiber contains a large number of silver nanoparticles, providing a theoretical basis for the antibacterial property of the fiber. Figure 4 (c) in Figure 4 is the distribution map of the elements contained in the sericin in-situ reduced silver-loaded PET fiber. It can be seen from the figure that silver nanoparticles are uniformly distributed on the surface of the PET fiber, which is attributed to the chelation coordination and in-situ reduction of sericin. Sericin, as a dispersant and reducing agent, can chelate Ag + uniformly on the surface of the PET fiber and reduce it to silver nanoparticles, which are firmly bound to the surface of the PET fiber. This further confirms that the preparation method of the sericin in-situ reduced silver-loaded PET fiber can solve the problem of poor dispersion of the antibacterial agent silver nanoparticles on the PET surface.

[0085] To further confirm that the in-situ reduction reaction occurred on the surface of the PET fiber, the experiment characterized the chemical structure changes of the PET fiber before and after modification by infrared spectroscopy, and the results are as Figure 5 shown. Figure 5 It is the infrared spectrum of the sericin in-situ reduced silver-loaded PET fiber. It can be seen from the figure that the infrared spectrum of polyethylene terephthalate fiber (PET fiber) has the following characteristic absorption bands: the stretching vibration of the carbonyl group (C=O) at 1709 cm -1 , and the C-O-C stretching vibrations at 1240 cm -1 and 1088 cm -1 . These absorption peaks together indicate the presence of ester groups in the molecule. Among them, the two strong absorption peaks with similar intensities at 1240 cm -1 and 1088 cm -1 are the characteristic absorption peaks of the terephthalic acid group. In addition, rich absorption peaks appear in the range of 700 - 900 cm -1 , indicating that the molecule contains a benzene ring structure. The absorption peak at 718 cm -1 is attributed to the out-of-plane bending vibration of the hydrogen atoms on the para-disubstituted benzene ring. Although not very typical, it can still be used as one of the evidences for the presence of the terephthalic acid group. The absorption peak at 865 cm -1The absorption peak at this position is attributed to the out-of-plane bending vibration of two adjacent C-H bonds on the aromatic ring. ~2920 cm -1 The absorption peak corresponds to the stretching vibration of the C-H bond of the benzene ring. In addition, there should be multiple absorption peaks related to the benzene ring skeleton vibration in the range of 1450 - 1620 cm -1 However, due to the high molecular symmetry, the intensities of these absorption peaks are weak and not very prominent. At the same time, as Figure 5 shows, the absorption peaks of sericin protein molecules near 1585, 1505 cm and 1405 cm -1 represent the absorption bands of amide I band, amide II band and amide III band respectively. Amide I is mainly caused by the stretching vibration of the C=O group, indicating the presence of β-turn structure in sericin protein. The absorption band of amide II represents the simultaneous N-H bending and C-N stretching vibrations. At the same time, the generation of amide III is caused by the combination of C-N stretching vibration and in-plane N-H bending vibration, which indicates that there are a large number of random coils in the secondary structure of sericin protein. In addition, the absorption peaks of sericin protein at 1505, 1075 cm -1 are caused by the bending vibrations of C-H and -OH and the C-C stretching vibration in the side chain of sericin protein respectively. There is an obvious single peak at 3057 cm -1 in the sericin protein molecule, which is a characteristic absorption peak formed by the superposition of N-H stretching vibration and O-H stretching vibration. As can be seen from Figure 5 , no new signal peaks appear in the molecular structure of the PET fiber after oxygen plasma treatment, indicating that the oxygen plasma treatment does not damage the PET macromolecular chain structure and retains the complete structure and excellent physical and chemical properties of PET. The PET fiber treated with oxygen plasma can undergo the following reactions:

[0086] RH → R· + H·

[0087] R· + O 2 → ROO·

[0088] ROO· + R 1 H → ROOH + R 1 ·

[0089] R· + O· → RO·

[0090] This reaction shows that the C—C bond in the PET molecule is broken during the plasma treatment and then recombines with oxygen atoms to form oxygen-containing polar groups. Therefore, the oxygen plasma treatment can not only increase the surface roughness of the fiber, but also introduce hydrophilic polar groups such as hydroxyl, carboxyl and aldehyde groups on the surface of the PET fiber, thus significantly improving the hydrophilicity of the PET fiber. This surface modification provides favorable conditions for the subsequent plasma grafting of sericin protein.

[0091] It should be noted that the silver-loaded PET fiber shows obvious carbonyl (C=O) stretching vibration at 1710 cm -1 and the intensity is significantly higher than that of the oxygen plasma-treated PET fiber. This indicates that under the catalysis of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide / N-hydroxysuccinimide, the carboxyl group (COOH) on the surface of the PET fiber obtained by oxygen plasma reacts with the free amino group in sericin to form an amide bond, and the carbonyl (C=O) in the amide bond significantly increases the peak intensity at 1710 cm -1 . The reaction process is mainly that 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide first reacts with the free carboxyl group on the PET surface to form an O-acylurea intermediate with amino-reactive activity. This intermediate reacts with the amino group in sericin to form a bond between the two compounds through an amide bond. However, this intermediate is very unstable in aqueous solution and is prone to hydrolysis. By adding N-hydroxysuccinimide, this intermediate can be converted into an N-hydroxysuccinimide ester with amino-reactive activity, thus greatly improving the efficiency of the condensation reaction mediated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. At the same time, at 1565 cm -1 , 1500 cm -1 , 1408 cm -1 , the absorption peak signals of the amide I band, amide II band, and amide III band appear, but the peak intensities at these three places decrease significantly. This is because of the amide cross-linking between the oxygen plasma-treated PET and sericin molecules by the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide / N-hydroxysuccinimide catalytic cross-linking mechanism, which reduces the corresponding primary amino group number and increases the amide bond. In the Fourier transform infrared spectrum of the silver-loaded PET fiber after catalytic cross-linking, it is mainly manifested as a decrease in the ratio of the peak intensities of the amide I band, amide II band, and amide III band, that is, the absorption peak area ratio at 1565 cm -1 , 1500 cm-cm -1 , and 1408 cm -1 decreases. The changes in these absorption peak intensities further confirm that the oxygen plasma-treated PET and sericin molecules have undergone a cross-linking reaction through catalysis. At 3357 cm -1 , an obvious stretching vibration peak of -OH appears on the PET surface, indicating that the hydrophilicity of the silver-loaded PET fiber grafted with sericin is significantly improved, which will be beneficial to the expansion of the application fields of silver-loaded PET. And these cross-linked sericin proteins, as chelating agents, can bind Ag 3 in the AgNO +It is firmly bound to the surface of PET fibers through coordination. At the same time, sericin also has natural affinity and three-dimensional structure, which provides a stable carrier for metal nanoparticles. This structure not only helps to prevent the aggregation of metal particles, but also improves the efficiency of catalytic reduction. Finally, tyrosine, aspartic acid, glutamic acid, etc. rich in sericin have reducing ability. As a reducing agent, it can reduce the Ag + chelated on the surface of PET fibers in-situ to silver nanoparticles and firmly bind them to the surface of PET fibers.

[0092] Figure 6 It is a diagram for qualitative test of the antibacterial property of sericin in-situ reduced silver-loaded PET fibers. Figure 6 (a) is the antibacterial test diagram of PET fibers before modification against Staphylococcus aureus. It can be seen that there is no inhibition zone, indicating that unmodified PET fibers do not have antibacterial property. Figure 6 (b) is the antibacterial picture of PET fibers after modification. It can be seen that there is an obvious inhibition zone, indicating that sericin in-situ reduced silver-loaded PET fibers have excellent antibacterial property against Staphylococcus aureus. This is attributed to the high antibacterial effect of the silver nanoparticle antibacterial agent on the surface of PET fibers.

[0093] Table 1 is a quantitative analysis table of the antibacterial property of sericin in-situ reduced silver-loaded PET fibers against Staphylococcus aureus and Escherichia coli. Two representative Gram-negative and positive bacteria (Staphylococcus aureus, S. aureus and Escherichia coli, E. coli ) were selected for the antibacterial experiment to simulate and verify the antibacterial property of sericin in-situ reduced silver-loaded PET fibers in practical applications. For the convenience of the operation of the antibacterial experiment, the aerogel was compressed into a sheet before the test. According to "GB / T20944.3-2008 Textiles - Evaluation of antibacterial properties - Part 3: Oscillation method", the samples of sericin in-situ reduced silver-loaded PET fibers were cut into pieces and put into a flask, and then 70 mL of phosphate buffer solution (PBS, pH≈7.2) and 5 mL of bacterial solution (3×10 5 -4×10 5cfu / mL), and then the flask was shaken at 24 °C for 18 h; 1 mL of the culture solution was taken out, diluted, and evenly dispersed in an agar plate, incubated at 37 °C for 24 - 48 h, and then the number of colonies grown was counted. The antibacterial rate was calculated by the formula, and the results are shown in Table 1 (the unit of each data in Table 1 is %). It can be seen from Table 1 that the unmodified PET fiber has basically no antibacterial effect on Staphylococcus aureus and Escherichia coli, which is attributed to the structural stability and chemical inertness. The antibacterial rates of the PET fiber before modification against Staphylococcus aureus and Escherichia coli were 2.14% and 1.47% respectively, and after 30 washes, the antibacterial rates were 0.92% and 0.43% respectively. The antibacterial rates of the sericin in-situ reduced silver-loaded PET fiber against Staphylococcus aureus and Escherichia coli were 99.95% and 97.38% respectively. This is mainly because silver nanoparticles will release silver ions (Ag + ), and these silver ions can directly damage the cell membrane structure of bacteria, resulting in the rupture of the cell membrane and the leakage of the contents, thus inhibiting the growth and reproduction of bacteria. At the same time, silver nanoparticles can induce bacteria to produce a large number of reactive oxygen species (ROS), and these free radicals will attack the cell components of bacteria, such as proteins, DNA, and lipids, thus interfering with the normal metabolism and physiological functions of bacteria. Silver nanoparticles can penetrate the cell membrane of bacteria, resulting in a change in the cell membrane permeability, causing the substances inside the cell to flow out, and ultimately leading to the death of bacteria. At the same time, it can be seen that after 30 washes, the antibacterial rates of the sericin in-situ reduced silver-loaded PET fiber against Staphylococcus aureus and Escherichia coli still reach more than 90% and 85% respectively, indicating that its antibacterial effect is persistent, and the sericin in-situ reduced silver-loaded PET fiber has antibacterial and wash-resistant properties. In summary, the different antibacterial effects verify the antibacterial effect of the sericin in-situ reduced silver-loaded PET fiber, which also provides theoretical support and potential for the sericin in-situ reduced silver-loaded PET fiber in practical antibacterial applications.

[0094] Table 1

[0095]

[0096] Figure 7 is the moisture regain rate diagram of the sericin in-situ reduced silver-loaded PET fiber. Activated PET fiber rich in oxygen-containing active groups such as carboxyl groups was obtained by treating PET with oxygen plasma, while at the same time increasing the surface roughness and wettability of the fiber. Further. Sericin was firmly grafted onto the surface of the PET fiber in the form of covalent bonding, endowing the PET fiber with the biocompatibility, skin-friendly property, and functionality of sericin. Such as Figure 7As shown, compared with the 0.4% official regain of recycled PET, the regain of the fibers prepared by this technology reaches 2.5%, which is more than 6 times higher. This makes the PET fibers approach the regain of natural cotton fibers, significantly improving hydrophilicity. The sericin protein in-situ reduced silver-loaded PET fibers have excellent skin-friendly and wettability properties.

[0097] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification.

Claims

1. A method for preparing silver-loaded PET fiber by in-situ reduction of sericin, characterized in that: The following steps are involved: The PET fibers are treated with oxygen plasma to obtain activated PET fibers rich in carboxyl groups; The activated PET fiber is immersed in a sericin solution for modification to obtain a grafted modified PET fiber; The grafted modified PET fiber is placed in a silver nitrate solution, the silver ions are chelated on the surface of the PET fiber by using sericin, and the reducing amino acid contained in the sericin is used as a reducing agent to reduce the silver ions into silver nanoparticles through an in-situ reduction reaction, thereby obtaining sericin in-situ reduced silver-loaded PET fiber; The step of immersing the activated PET fiber in a sericin solution for modification to obtain the grafted modified PET fiber specifically comprises: The activated PET fiber is immersed in a sericin solution, and a composite catalyst is used to catalyze a cross-linking reaction so that the activated PET fiber and the sericin are firmly bonded to form an amide covalent bond to obtain a grafted modified PET fiber; the composite catalyst is a composite system of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide; the mass ratio of the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide to N-hydroxysuccinimide is (1.8-2.2):1; The sericin solution is an ethanol-water solution of sericin; the mass concentration of sericin in the ethanol-water solution is 1%-10%; the ethanol-water solution is composed of anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is (8.5-9.5):(0.5-1.5).

2. The method for preparing silver-loaded PET fiber by in-situ reduction of sericin according to claim 1, characterized in that: The power of oxygen plasma treatment is 10-300 W, and the time is 5-60 min.

3. The method for preparing silver-loaded PET fiber by in-situ reduction of sericin according to claim 1, characterized in that: The pH value of the reaction system for the catalytic cross-linking reaction is 3-6, the reaction temperature is 1-10°C, and the reaction time is 24-72 h.

4. The method for preparing silver-loaded PET fiber by in-situ reduction of sericin according to claim 1, characterized in that: The mass volume ratio of the activated PET fiber to the sericin solution is 1kg:(30-100)L.

5. The method for preparing silver-loaded PET fiber by in-situ reduction of sericin according to claim 1, characterized in that: The silver nitrate solution is an aqueous solution of silver nitrate, and its concentration is 50-100 mmol / L.

6. The method for preparing silver-loaded PET fiber by in-situ reduction of sericin according to claim 1 or 5, characterized in that: The mass volume ratio of the grafted modified PET fiber to the silver nitrate solution is 1kg:(30-100)L.

7. A PET fiber loaded with silver by in-situ reduction of sericin prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The silver nanoparticles in the sericin in-situ reduced silver-loaded PET fiber are loaded on the surface of the grafted modified PET fiber through coordination chelation; the grafted modified PET fiber is a PET fiber bonded with sericin through amide covalent bonds.

8. Use of the sericin in-situ reduced silver-loaded PET fiber as claimed in claim 7 in the preparation of an antibacterial agent.

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