Silk fibroin nano fibril with uniform size and preparation method thereof
By treating silkworm silk with a DMSO/water/strong alkali mixed solution, combined with microwave heating and centrifugation, uniform silk fibroin nanofibers were prepared. This method solves the problems of noise pollution and high energy consumption in the preparation process of existing technologies, and achieves high-efficiency preparation with low noise and low energy consumption.
Patent Information
- Application Number
- CN202511996469.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-02-06
AI Technical Summary
Existing technologies are difficult to prepare silk fibroin nanofibers with uniform diameter in an efficient and low-energy-consumption manner, and mechanical shearing methods have problems such as noise pollution and high energy consumption.
Degummed silk was treated with a DMSO/water/strong alkali mixed solution, and then chemically dissolved by microwave heating and constant temperature incubation, combined with centrifugation, to prepare silk fibroin nanofibers with uniform size.
This method enables the preparation of silk fibroin nanofibers with uniform diameters of 60-80 nm with low noise and low energy consumption, solving the problems of noise pollution and high energy consumption in the preparation process of existing technologies and improving the preparation efficiency.
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Figure CN121471540A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterial preparation technology, and relates to a uniform-sized silk fibroin nanofiber and its preparation method. Specifically, it is a method for preparing uniform-sized silk fibroin nanofiber by treating with a special chemical solution. Background Technology
[0002] Silk, a natural polymer fiber composed of sericin and fibroin, possesses high mechanical properties, is fine, soft, and lustrous, earning it the title of "Queen of Fibers." It was one of the earliest natural fibers used as a textile raw material. With the development of biotechnology and materials science, as well as interdisciplinary innovation, silk fiber is no longer limited to its use as a high-end textile raw material; it is increasingly being developed into various high-value-added functional materials with broad application prospects in biomedicine, tissue engineering, and optoelectronic sensing. However, previous reports on the preparation of various functional materials from fibroin generally involved dissolving fibroin fibers in a high-concentration salt solution to obtain a regenerated fibroin macromolecular precursor solution, which was then processed using various material processing techniques to obtain materials with different structures and properties. During the dissolution process, the multi-scale protofibrillary structure within the fibroin fiber is completely deconstructed, and the original crystalline structure that plays a crucial role in mechanical properties is destroyed, resulting in a sharp decline in the mechanical properties of the materials prepared from the regenerated fibroin solution. In light of this, in recent years, scholars both domestically and internationally have proposed using a combination of chemical pretreatment and mechanical shearing to open some hydrogen bonds in the crystalline regions of silk fibroin fibers, thereby obtaining silk fibroin micro / nanoscale fibers. Because this method preserves the internal crystalline structure of the silk fibroin fiber to the maximum extent, it exhibits excellent mechanical properties, making it a promising reinforcing phase for composite material preparation. However, most reported methods for obtaining silk fibroin micro / nanofibers currently involve chemical pretreatment and physical shearing, which suffers from high noise and energy consumption during the preparation process. Furthermore, the diameter of the obtained silk fibroin nanofibers is between the micrometer and nanometer scales, making it difficult to obtain uniformly sized silk fibroin nanofibers with diameters within 100 nm.
[0003] Patent CN118480931A discloses a method for preparing silk fibroin nanofibers from waste silk fabrics. The method uses a high-speed mixer, high-speed pulverizer, homogenizer, emulsifier or homogenizer for mechanical exfoliation to prepare silk fibroin nanofibers. The obtained silk fibroin nanofibers have a diameter of 70-180 nm and a length of 0.5-1 μm. The aspect ratio of the silk fibroin nanofibers prepared by this method is not uniform, which affects the performance of the materials or products subsequently produced.
[0004] Patent CN118480877A discloses a method for preparing silk fibroin nanofibers by recycling waste silk fabrics. The main steps in preparing silk fibroin nanofibers involve mechanical exfoliation using one or more of the following: a high-speed mixer, a high-speed pulverizer, a homogenizer, an emulsifier, or a homogenizer. This method belongs to the category of preparing silk fibroin nanofibers using mechanical shearing and exfoliation. However, the silk fibroin nanofibers obtained by this method have a diameter distribution between 70-180 nm, exhibiting non-uniform size and a relatively large diameter compared to traditional nanofibers.
[0005] Patent CN 114908433 A discloses a physical method for preparing silk fibroin nanofibers, the main steps of which include first subjecting the silk fibroin fibers to high-temperature and high-pressure pretreatment, and then subjecting them to ultrasonic crushing. The silk fibroin nanofibers prepared by this method have a diameter between 30-500 nm, exhibiting poor dimensional uniformity, and the method of high-temperature and high-pressure pretreatment followed by ultrasonic treatment consumes a large amount of energy.
[0006] Patent CN114249982A discloses a method for preparing high-strength, high-modulus silk materials and their applications. Although a chemical exfoliation method is used to prepare silk fibroin nanofibers, the purpose is to prepare high-modulus silk materials. The requirements for the diameter and fineness of the silk fibroin nanofibers are not high. The size of the nanofibers is between 200-300 nm, which is significantly larger and less uniform in the field of nanofibers.
[0007] In view of the above-mentioned technical problems, this invention is proposed. Summary of the Invention
[0008] To address the shortcomings of existing technologies, this invention provides a highly efficient and energy-saving method for preparing silk fibroin nanofibers by dissolving them in a specially formulated chemical solvent.
[0009] The first objective of this invention is to provide a method for preparing silk fibroin nanofibers with uniform size, comprising the following steps: S1: Cut the degummed silk into small segments of 5-15 mm; S2: Prepare a DMSO / water / strong alkali mixture; S3: Soak the shredded silk from step S1 in a DMSO (dimethyl sulfoxide) / water / strong alkali mixed solution to obtain a solution system soaked in silk. S4: Place the solution system impregnated with silk in a sealed container and heat it to obtain a solution system containing nanofibers; S5: Centrifuge the solution system containing nanofibers and take the supernatant to obtain silk fibroin nanofibers with uniform size.
[0010] Preferably, the mass ratio of silk to mixed solution in step S1 is 1:(5-1000).
[0011] Preferably, the mass ratio of DMSO, water and strong alkali in step S2 is (90-95):(3-5):(2-5).
[0012] Preferably, the strong alkali is one or more of NaOH, LiOH, KOH, Ca(OH)2, and Ba(OH)2.
[0013] Preferably, the water is deionized water or ultrapure water.
[0014] Preferably, the heating treatment in step S4 is as follows: first, microwave heating at 60-100℃ for 1-120 min, and then transferring to a heating device for continuous incubation at 40-80℃ for 12-24 h.
[0015] Preferably, the heating treatment in step S4 is as follows: placing the object in a heating device, setting the temperature to 40-80°C, and incubating it in the heating device for 12-24 hours.
[0016] Preferably, the heating device is an instrument capable of constant temperature heating, such as a water bath, oil bath, oven, or constant temperature oscillator.
[0017] Using the above technical solution, when the silk in the sealed container completely dissolves into a homogeneous solution without any other solids, a solution system containing nanofibers is obtained. Furthermore, higher heating temperatures and longer heating times result in a more complete reaction. However, considering safety, prolonged heating and incubation are not recommended; 12-24 hours is preferred.
[0018] Preferably, the centrifugation process in step S5 is centrifugation at 1000-10000 rpm for 1-30 min.
[0019] Preferably, the silk in step S1 is one or more of domesticated silkworm silk, tussah silk, and wild silkworm silk.
[0020] Preferably, the degummed silk in step S1 is cut into small segments of 5-10 mm.
[0021] Degummed silk fibroin is mainly composed of silk fibroin protein, whose molecular structure contains numerous intermolecular forces such as hydrogen bonds and van der Waals forces. These forces cause silk fibroin protein to form a stable aggregated structure (including crystalline and amorphous regions), which is difficult to dissolve under normal conditions and maintains a nanoscale fibril morphology. DMSO can penetrate and disrupt the amorphous regions in silk fibroin. At the same time, DMSO can form hydrogen bonds with silk fibroin protein, disrupting the original hydrogen bonds between silk fibroin proteins. A small amount of water can promote the ionization of strong bases to release OH-. - An appropriate amount of strong base ionizes to produce OH- -It can attack some peptide bonds in the peptide chain of silk fibroin. Only through the synergistic effect of DMSO, water and strong alkali mixed solution can a better fiber-breaking effect be achieved to obtain nanofibers. Since the present invention uses a chemical method to obtain nanofibers, the nanofibers obtained are more uniform in diameter compared with the traditional mechanical cutting and peeling method.
[0022] A second objective of the present invention is to provide uniformly sized silk fibroin nanofibers obtained by the above method, wherein the diameter of the silk fibroin nanofibers is 60-80 nm.
[0023] The beneficial effects of this invention are: (1) The preparation method of the present invention uses degummed silk to remove sericin impurities. The degummed fibroin is subjected to swelling treatment to initially destroy the intermolecular forces and hydrogen bonds of the fibroin macromolecules. Cutting the degummed silk into small segments makes it easier to dissolve in a specially prepared chemical solution (i.e., a mixture of DMSO / water / strong alkali) and can make the obtained fibroin nanofibers more uniform in diameter. During the chemical dissolution process, microwave heating followed by heating and incubation in an oven can accelerate the dissolution rate, which is related to the more intense movement between molecules during heating. Finally, centrifuging the dissolved fibroin nanofiber solution yields a fibroin nanofiber suspension with uniform diameter.
[0024] (2) Compared with existing technologies, the present invention obtains silk fibroin nanofibers by dissolving silk fibroin in a chemical solution. Current methods for preparing silk fibroin nanofibers almost all employ physical fragmentation methods to subject the silk fibroin to severe mechanical shearing. These physical fragmentation methods utilize various mechanical shearing actions, resulting in noise pollution during the preparation process. Furthermore, to obtain smaller-sized silk fibroin nanofibers, multiple shearing operations are typically required, leading to long processing times, high energy consumption, and low efficiency, which does not align with the concept of sustainable development. The present invention obtains silk fibroin nanofibers without mechanical shearing, resulting in low energy consumption, high efficiency, and no noise pollution. The yield of the obtained silk fibroin nanofibers is high, with a diameter between 60-80 nm and uniform size. Attached Figure Description
[0025] Figure 1 This is a physical image of the silk fibroin nanofiber solution in Example 1 of the present invention.
[0026] Figure 2 This is a scanning electron microscope image of silk fibroin nanofibers in Example 1 of the present invention.
[0027] Figure 3 This is a statistical diagram showing the diameter distribution of silk fibroin nanofibers in Example 1 of the present invention. Detailed Implementation
[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.
[0029] The technical solution of this invention is as follows: A method for preparing uniformly sized silk fibroin nanofibers includes the following steps: S1: Cut the degummed silk into small segments of 5-15 mm; S2: Prepare a DMSO / water / strong alkali mixture; S3: Soak the shredded silk from step S1 in a mixed solution of DMSO / water / strong alkali to obtain a solution system containing silk. S4: Place the solution system soaked in silk in a sealed container, first microwave heat treatment, and then heat incubate in a heating device to obtain a solution system containing nanofibers; S5: Centrifuge the solution system containing nanofibers and take the supernatant to obtain silk fibroin nanofibers with uniform size.
[0030] In some embodiments, the mass ratio of silk to mixed solution in step S1 is 1:(5-1000) (non-limiting examples, such as 1:5, 1:100, 1:300, 1:500, 1:700, 1:1000, etc.).
[0031] In some embodiments, the mass ratio of DMSO, water, and strong alkali in step S2 is (90-95):(3-5):(2-5) (non-limiting examples, such as 95:3:2, 50:1:1, 92:5:2, 93:4:3, etc.).
[0032] In some embodiments, the strong base is one or more of NaOH, LiOH, KOH, Ca(OH)2, and Ba(OH)2.
[0033] In some embodiments, the water is deionized water or ultrapure water.
[0034] In some embodiments, the heating treatment in step S4 is as follows: first, microwave heating is performed at 60-100°C (non-limiting examples, such as 60°C, 70°C, 80°C, 90°C, 100°C, etc.) for 1-120 min (non-limiting examples, such as 20 min, 50 min, 80 min, 100 min, 120 min, etc.), and then the mixture is transferred to a heating device and incubated at 40-80°C (non-limiting examples, such as 40°C, 50°C, 60°C, 70°C, 80°C, etc.) for 2-10 h (non-limiting examples, such as 2 h, 3 h, 5 h, 8 h, 9 h, 10 h, etc.).
[0035] In some embodiments, the heating treatment in step S4 is: placing the device in a heating apparatus, setting the temperature to 40-80°C (non-limiting examples, such as 40°C, 50°C, 60°C, 70°C, 80°C, etc.), and incubating in the heating apparatus for 5-15 h (non-limiting examples, such as 5 h, 8 h, 10 h, 12 h, 15 h, etc.).
[0036] In some embodiments, the heating device is an instrument capable of constant temperature heating, such as a water bath, oil bath, oven, or constant temperature shaker.
[0037] In some embodiments, the centrifugation process in step S5 is centrifugation at 1000-10000 rpm for 2-10 min.
[0038] In some embodiments, the silk in step S1 is one or more of domesticated silkworm silk, tussah silk, and wild silkworm silk.
[0039] In some embodiments, the degummed silk in step S1 is cut into small segments of 5-10 mm (non-limiting examples, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.).
[0040] A second objective of the present invention is to provide uniformly sized silk fibroin nanofibers obtained by the above method, wherein the diameter of the silk fibroin nanofibers is 60-80 nm.
[0041] Example 1 S1: After degumming the silkworm silk, degummed silk is obtained. The degummed silk is then cut into 5 mm pieces with scissors.
[0042] S2: Prepare a mixed solution of DMSO / strong base. The strong base is NaOH. Weigh 3 g of NaOH, 246 g of DMSO, and 1 g of deionized water. First, dissolve NaOH in deionized water and mix well. Then pour the mixture into DMSO. Stir the mixed solution with a magnetic stirrer at 500 rpm for 5 min and then pour it into a capped reagent bottle.
[0043] S3: Soak the shredded degummed silk in the prepared mixed solution, heat the reagent bottle in a microwave at 80℃ for 60 min, and then incubate it in an oil bath at 60℃ for 16 h to obtain the silk fibroin nanofiber solution.
[0044] S4: Centrifuge the above silk fibroin nanofiber solution at 5000 rpm for 5 min, take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size and a mass fraction of 2%.
[0045] Figure 1 The image shows the actual silk fibroin nanofiber solution in Example 1, indicating that the silk is completely dissolved and presents a homogeneous solution without any other solids.
[0046] Figure 2 This is a scanning electron microscope image of the silk fibroin nanofibers in Example 1.
[0047] Figure 3 The figure shows the diameter distribution of silk fibroin nanofibers in Example 1, indicating that the diameter of most silk fibroin nanofibers is between 60-80 nm.
[0048] Example 2 S1: After degumming the tussah silk, degummed silk is obtained. The degummed silk is then cut into 5 mm segments with scissors.
[0049] S2: Prepare a mixed solution of DMSO and a strong base, using KOH as the strong base. Weigh out 3 g of KOH, 195 g of DMSO, and 2 g of ultrapure water. First, dissolve the KOH in the ultrapure water and mix thoroughly. Then, pour the KOH into the DMSO. Stir the mixture at 500 rpm for 6 minutes using a magnetic stirrer, and then pour it into a capped reagent bottle.
[0050] S3: Then, soak the shredded degummed silk in the prepared mixed solution, microwave the reagent bottle at 70℃ for 120 min, and then place the reagent bottle in a 70℃ oven for 12 h to obtain the silk fibroin nanofiber solution.
[0051] S4: Centrifuge the above silk fibroin nanofiber solution at 6000 rpm for 5 min, and take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size and a mass fraction of 2.5%.
[0052] Example 3 S1: After degumming the wild silk, degummed silk is obtained. The degummed silk is then cut into 5 mm pieces with scissors.
[0053] S2: Prepare a mixed solution of DMSO / strong base. The strong base is LiOH. Weigh 2 g of LiOH, 195 g of DMSO, and 3 g of deionized water. First, dissolve LiOH in deionized water and mix well. Then pour it into DMSO. Stir the mixed solution at 800 rpm for 4 min on a magnetic stirrer and pour it into a capped reagent bottle.
[0054] S3: Then, the shredded degummed silk is soaked in the prepared mixed solution. The reagent bottle is microwave-treated at 100℃ for 40 min. Then, the reagent bottle is placed in a 70℃ oven and incubated for 14 h to obtain silk fibroin nanofiber solution.
[0055] S4: Centrifuge the above silk fibroin nanofiber solution at 8000 rpm for 6 min, take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size and a mass fraction of 2.5%.
[0056] Example 4 S1: After degumming the silkworm silk, degummed silk is obtained. The degummed silk is then cut into 15 mm segments with scissors.
[0057] S2: Prepare a mixed solution of DMSO / strong base. The strong base is Ca(OH)2. Weigh 3 g of Ca(OH)2, 246 g of DMSO, and 1 g of deionized water. First, dissolve Ca(OH)2 in deionized water and mix well. Then pour the mixture into DMSO. Stir the mixed solution with a magnetic stirrer at 500 rpm for 5 min and then pour it into a capped reagent bottle.
[0058] S3: Soak the shredded degummed silk in the prepared mixed solution, microwave the reagent bottle at 70℃ for 50 min, cover the reagent bottle and incubate it in an 80℃ oven for 12 h to obtain silk fibroin nanofiber solution.
[0059] S4: Centrifuge the above silk fibroin nanofiber solution at 8000 rpm for 2 min, and take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size.
[0060] Example 5 S1: After degumming the silkworm silk, degummed silk is obtained. The degummed silk is then cut into 10 mm segments with scissors.
[0061] S2: Prepare a mixed solution of DMSO / strong base. The strong base is Ba(OH)2. Weigh 2 g of Ba(OH)2, 195 g of DMSO, and 3 g of deionized water. First, dissolve Ba(OH)2 in deionized water and mix well. Then pour the mixture into DMSO. Stir the mixed solution with a magnetic stirrer at 500 rpm for 5 min and then pour it into a capped reagent bottle.
[0062] S3: Soak the shredded degummed silk in the prepared mixed solution, microwave the reagent bottle at 70℃ for 50 min, and then incubate the reagent bottle in a 40℃ oven for 15 h to obtain the silk fibroin nanofiber solution.
[0063] S4: Centrifuge the above silk fibroin nanofiber solution at 3000 rpm for 10 min, take the supernatant, and obtain a silk fibroin nanofiber suspension with uniform size.
[0064] Example 6 S1: Degumming the tussah silk yields degummed silk. The degummed silk is then cut into 10 mm segments with scissors.
[0065] S2: Prepare a mixed solution of DMSO and a strong base, using LiOH as the strong base. Weigh out 3 g of LiOH, 195 g of DMSO, and 2 g of ultrapure water. First, dissolve the LiOH in the ultrapure water and mix thoroughly. Then, pour the mixture into the DMSO. Stir the mixture at 500 rpm for 6 minutes using a magnetic stirrer, and then pour it into a capped reagent bottle.
[0066] S3: Then, the shredded degummed silk is soaked in the prepared mixed solution, the reagent bottle is microwaved at 90℃ for 100 min, and then the reagent bottle is placed in an oil bath at 70℃ for 16 h to obtain silk fibroin nanofiber solution.
[0067] S4: Centrifuge the above silk fibroin nanofiber solution at 6000 rpm for 5 min, and take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size.
[0068] Example 7 S1: After degumming the wild silk, degummed silk is obtained. The degummed silk is then cut into 12 mm segments with scissors.
[0069] S2: Prepare a mixed solution of DMSO and a strong base, using Ca(OH)₂. Weigh out 3 g of Ca(OH)₂, 195 g of DMSO, and 2 g of ultrapure water. First, dissolve Ca(OH)₂ in ultrapure water and mix thoroughly. Then, pour the solution into the DMSO. Stir the mixture at 500 rpm for 6 minutes using a magnetic stirrer, and then pour it into a capped reagent bottle.
[0070] S3: Then, the shredded degummed silk is soaked in the prepared mixed solution, the reagent bottle is microwaved at 60℃ for 120 min, and then the reagent bottle is placed in an oil bath at 80℃ for 12 h to obtain silk fibroin nanofiber solution.
[0071] S4: Centrifuge the above silk fibroin nanofiber solution at 10000 rpm for 2 min, and take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size.
[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0073] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing silk fibroin nanofibers with uniform size, characterized in that, Includes the following steps: S1: Cut the degummed silk into small segments of 5-15 mm; S2: Prepare a DMSO / water / strong alkali mixture; S3: Soak the shredded silk from step S1 in a mixed solution of DMSO / water / strong alkali to obtain a solution system containing silk. S4: Place the solution system containing silk described in step S3 into a sealed container, heat it with microwave for 1-120 min, and then incubate it at a certain temperature for 12-24 h to obtain a solution system containing silk fibroin nanofibers. S5: Centrifuge the solution system containing silk fibroin nanofibers described in step S4, and take the supernatant to obtain a silk fibroin nanofiber suspension with uniform size.
2. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 1, characterized in that, In step S2, the mass ratio of DMSO, water, and strong alkali is (90-95):(3-5):(2-5).
3. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 2, characterized in that, The strong base is one or more of NaOH, LiOH, KOH, Ca(OH)2, and Ba(OH)2.
4. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 2, characterized in that, The water is deionized water or ultrapure water.
5. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 1, characterized in that, The heating treatment in step S4 is as follows: first, microwave heating at 60-100℃ for 1-120 min, then transfer to a heating device and incubate at 40-80℃ for 12-24 h.
6. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 1, characterized in that, The centrifugation process in step S5 is centrifugation at 1000-10000 rpm for 1-30 min.
7. The method for preparing uniformly sized silk fibroin nanofibers as described in claim 1, characterized in that, The silk in step S1 is one or more of the following: domesticated silkworm silk, tussah silk, and wild silkworm silk.
8. The silk fibroin nanofibers with uniform size obtained by the method according to any one of claims 1-7, characterized in that, The diameter of the silk fibroin nanofibers is 60-80 nm.