Metal ion reinforced antibacterial silk protein fiber and preparation method thereof

Abstract

The invention discloses a metal ion enhanced antibacterial silk protein fiber and a preparation method thereof, comprising the following steps: S1: degumming silk in an alkaline salt solution, drying naturally and then drying to obtain degummed silk; S2: preparing a dissolving solution containing transition metal ions, calcium ions and an organic solvent, dissolving the degummed silk in the dissolving solution to obtain a spinning solution of a certain concentration; S3: squeezing or sucking the spinning solution into a multi-channel spinning chip through a metering device; S4: squeezing the spinning solution from an extrusion port through the chip into a coagulation bath containing a coagulant and a toughening agent of a certain concentration to form multiple strands of fiber fibrils; S5: after the multiple strands of fiber fibrils are out of the coagulation bath, they are subjected to differential stretching between stretching rollers, and finally a metal ion enhanced antibacterial silk protein fiber is obtained on a collecting roller. According to the invention, not only a high-performance regenerated fiber material is provided, but also an effective way for the resource utilization of waste silk is provided.

Description

Technical Field

[0001] The invention relates to the technical field of biological protein fiber preparation, and in particular to a metal ion-reinforced antibacterial silk protein fiber and a preparation method thereof. Background Art

[0002] Silk is a type of protein fiber formed by silkworms. It has excellent biocompatibility and degradability. It is widely used in biomedicine, industry and agriculture, such as surgical sutures, artificial ligaments, silk quilts, silk clothing and other fields. Silk can be mass-produced through artificial breeding. It can also be seen from the ancient Silk Road that silk and its subsequent processing are traditional textile technologies in my country and a manifestation of Chinese culture. However, as surgical sutures, the degradation rate of silk is far slower than that of regenerated silk, which undoubtedly limits its use in biomedicine. On the other hand, some waste silk will be produced in the weaving process and the disposal and recycling of waste silk clothing. If these waste silks are directly discarded, it will undoubtedly cause waste of resources and environmental damage. For this reason, how to optimize the rapid degradability of silk and the recycling of waste silk has become a scientific and technological problem that needs to be focused on research and development. Summary of the invention

[0003] The purpose of the present invention is to provide a metal ion antibacterial enhanced silk protein fiber and a preparation method thereof, so as to solve the problem in the prior art that silk cannot simultaneously meet the requirements of rapid degradation and waste silk recycling.

[0004] In order to achieve the above-mentioned invention object, the present invention adopts the following technical solutions: According to a first aspect of the present invention, a method for preparing metal ion-reinforced antibacterial silk protein fiber is provided, comprising the following steps: S1: degumming silk obtained by removing pupae from natural silkworm cocoons in an alkaline salt solution, drying naturally and obtaining degummed silk; S2: preparing a dissolving solution comprising transition metal ions, calcium ions and an organic solvent, dissolving the degummed silk in the dissolving solution to obtain a spinning solution of a certain concentration; the organic solvent is one or more of formic acid, hexafluoroisopropanol and trifluoroacetic acid, and the transition metal ion is Fe 3+ , Zn 2+ , Mn 2+ , Cu 2+ ,Mg 2+The concentration of transition metal ions is 0.1-1.0%, and the concentration of calcium ions is 1-10%; S3: the spinning solution is squeezed into or sucked into a multi-channel spinning chip through a metering device; S4: the spinning solution is squeezed from the extrusion port through the chip into a coagulation bath containing a certain concentration of coagulant and toughening agent to form a plurality of fiber fibrils; S5: after the plurality of fiber fibrils exit the coagulation bath, they are differentially stretched between stretching rollers, and finally a metal ion-reinforced antibacterial silk protein fiber is obtained on a collecting roller.

[0005] Preferably, in step S1, the solid-liquid mass ratio of the degumming is 1:10-1:1000, and the degumming lasts for 10-120 minutes.

[0006] Preferably, in step S2, the concentration of transition metal ions in the dissolving solution used is 0.5%, and the concentration of calcium ions is 5%.

[0007] Preferably, in step S2, the dissolving solution used contains 0.5% by mass of ferric chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

[0008] Preferably, in step S2, the dissolving solution used contains 0.5% by mass of manganese chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

[0009] Preferably, in step S4, the coagulation bath contains 50-60% ethanol and 3-5% glycerol by volume.

[0010] Preferably, in step S5, the number of strands of the plurality of fiber fibrils is 2-500.

[0011] Preferably, in step S1, the silk raw material is silk obtained from natural silk cocoons after pupation or waste silk.

[0012] Preferably, in step S5, the stretching ratio of the differential stretching is 4-10.

[0013] Preferably, the natural silk cocoons in step S1 are one or more of mulberry silk cocoons, tussah silk cocoons, etc., and mulberry silk cocoons are most preferred.

[0014] Preferably, the solute of the alkaline salt solution is one or more of sodium carbonate and sodium bicarbonate, and sodium carbonate is most preferred; the concentration of the alkaline salt solution is 0.01%-1.00%, and 0.05% is most preferred.

[0015] Preferably, the degumming lasts for a period of 10-120 min, most preferably 30 min.

[0016] Preferably, the degummed silk fibroin fibers in step S2 are dry degummed silk after natural drying; the degumming rate of the degummed silk fibroin fibers is 20%-35%, more preferably 25%-30%.

[0017] The organic solvent is one or more of formic acid, hexafluoroisopropanol, and trifluoroacetic acid, and formic acid is most preferred.

[0018] Preferably, the metering device in step S3 is a microinjection pump, a plunger pump, a metering pump or the like, and is most preferably a plunger pump; the multi-channel spinning chip is a microfluidic device containing a main channel and multiple branch channels; the chip is made of stainless steel or aluminum alloy resistant to organic solvents.

[0019] Preferably, the stretching rollers for the differential stretching in step S5 are stainless steel rollers with the same diameter but different rotation speeds; the stretching multiple of the differential stretching is 1-20, more preferably 4-10; the regenerated silk fibroin multifilament filaments are composed of a plurality of regenerated silk fibroin fiber filaments; the number of strands of the multi-strand fiber fibrils is 2-500, more preferably 5-50; the filaments are regenerated silk fibroin fibers with a length greater than 1000m.

[0020] According to a preferred embodiment of the present invention, a dissolving solution is prepared with a mass fraction of 0.5% ferric chloride and a mass fraction of 5% calcium chloride in the solvent. A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% is prepared by volume. After being fully stretched between differential stretching rollers with a total stretching multiple of 4 times, metal ion-enhanced antibacterial silk protein fibers are collected on a collecting roller 6, and mechanical properties are tested, with a stress of up to 686.4±33.4MPa and a strain of 28.3±4.6%.

[0021] According to the second aspect of the present invention, there is provided a metal ion enhanced antibacterial silk protein fiber prepared by the above method, wherein the metal ion enhanced antibacterial silk protein fiber has certain antibacterial properties and can effectively inhibit the growth and reproduction of microorganisms, wherein the microorganisms include: Escherichia coli and Staphylococcus aureus, and the antibacterial rate is ≥99.99%.

[0022] The metal ion reinforced antibacterial silk protein fiber prepared by the method of the present invention has a mechanical property stress of 50-1000MPa, more preferably 100-800MPa, and a strain of 5%-100%, more preferably 10%-80%.

[0023] It should be understood that, in addition to fibers directly derived from plants and animals, the methods for artificially preparing fibers can be roughly divided into melt spinning, dry spinning and wet spinning. Since protein fibers such as silk are not resistant to high temperatures, wet spinning is undoubtedly the only choice for preparing regenerated silk. The present invention dissolves silk in a specific solvent, and then extrude the spinning solution into a coagulation bath. After the fibers are out of the coagulation bath, they are oriented and shaped by post-stretching to obtain regenerated silk fibers with certain mechanical properties. In particular, by optimizing the process parameters of the spinning solution and the coagulation bath and steps such as doping with metal ions, regenerated silk protein fibers comparable to natural silk are obtained, which optimizes the degradation performance while also having a positive impact on resource recycling and environmental protection.

[0024] The key invention of the present invention is mainly that, by using organic solvents such as formic acid to dissolve silk, calcium ions are added as a dissolution promoter, and in particular, a certain amount of transition metal ions are added as a structural reinforcing agent to dissolve silk well and obtain a spinning solution with a certain viscosity. Then the spinning solution is extruded into a coagulation bath through a microfluidic device containing a main channel and multiple branch channels to obtain regenerated silk fibroin multifilament fibrils, and the number of monofilaments in the multifilament is determined by the number of branch channels of the microfluidic device, and the number of monofilaments is determined by the number of branches. The multifilament fibrils are coagulated into primary fibers with a certain solid morphology after solvent exchange in the coagulation bath, and the primary fibers are differentially stretched between differential stretching rollers, and the solvent volatilizes during the stretching process, and finally the regenerated silk fibroin multifilament long fibers with certain mechanical properties and antibacterial properties are collected on the collecting roller. When the spinning solution is sufficient, the fiber can be stretched continuously for more than 24 hours, and the purpose of continuous mass production can be achieved.

[0025] In summary, the present invention uses organic solvents such as formic acid and combines the dissolution-promoting and coordination-enhancing effects of metal ions to dissolve and spin silk in a one-step method, and winds to obtain regenerated silk fibroin fibers. The process is simple and convenient, and the mechanical properties of the obtained regenerated silk fibroin fibers are close to those of natural silk, providing a new technical method for the reuse of waste silk. The prepared regenerated silk fibroin fibers have good degradability, excellent mechanical properties and antibacterial properties, and can be further applied in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the experimental device, where 1-spinning solution inlet; 2-multi-channel chip; 3-coagulation bath; 4-first stretching roller; 5-second stretching roller; 6-collecting roller; Figure 2 is a scanning electron microscope cross-sectional view of the regenerated silk fibroin multifilament long fiber of the present invention (Example 4); Figure 3 is a fiber stress-strain curve diagram of Example 1 of the present invention; Figure 4 is a fiber stress-strain curve diagram of Example 2 of the present invention; Figure 5 is a fiber stress-strain curve diagram of Example 3 of the present invention; Figure 6 is a fiber stress-strain curve diagram of Example 4 of the present invention; Figure 7 This is a fiber stress-strain curve diagram of Example 5 of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0028] Example 1 According to this embodiment, a preparation process of metal ion reinforced antibacterial silk protein fiber is provided, combining Figure 1 The preparation process is described as follows: 1) Silk degumming The silk was cut into pieces after the pupae were removed, and the silk was placed in a 0.05% sodium carbonate solution, and the degummed silk was rinsed with purified water and dried. After drying, the mass of the degummed silk was weighed, and the degumming rate was calculated to be 27.6%.

[0029] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 0.5% ferric chloride mass fraction and 5% calcium chloride mass fraction in the solvent. The specific data are as follows: 0.225g ferric chloride, 2.0g calcium chloride, 37.9g ​​formic acid were weighed and stirred thoroughly to obtain a clear and transparent dissolving solution. 6g degummed silk was added to the dissolving solution and a spinning solution with a concentration of 13% was obtained after sufficient dissolution.

[0030] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0031] 4) Spinning like Figure 1 As shown, a 10-channel multi-channel chip 2 is used, and a plunger pump is used as a power source to suck the spinning liquid from the spinning liquid inlet 1 into the chip. After passing through the fine needle at the rear end of the chip, the spinning liquid is squeezed into the coagulation bath 3 to form nascent fibers. After solvent exchange in the coagulation bath, multiple nascent fibers are stretched onto the first stretching roller 4, pass through the second stretching roller 5, and are fully stretched between differential stretching rollers with a total stretching multiple of 4 times, and then regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller 6.

[0032] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fiber were tested, and the test results are as follows: Figure 3 As shown, the stress is 686.4±33.4MPa and the strain is 28.3±4.6%. The antibacterial performance of the material reaches more than 70%.

[0033] Example 2 1) Silk degumming The silk was cut into pieces after the pupae were removed, and the silk was put into a 0.05% sodium carbonate solution, and the degummed silk was rinsed with purified water and dried. After drying, the mass of the degummed silk was weighed, and the degumming rate was calculated to be 28.9%.

[0034] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 0.5% zinc chloride mass fraction and 5% calcium chloride mass fraction in the solvent. The specific data are as follows: 0.188g zinc chloride, 2.0g calcium chloride, 38.0g formic acid were weighed and stirred thoroughly to obtain a clear and transparent dissolving solution. 6g degummed silk was added to the dissolving solution and a spinning solution with a concentration of 13% was obtained after sufficient dissolution.

[0035] 3) Preparation of coagulation bath Prepare a coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% by volume, and fill a coagulation bath tank with a volume of 7 L and a length of 40 cm.

[0036] 4) Spinning A 10-channel aluminum alloy chip is used, and a plunger pump is used as the power source to suck the spinning into the chip. After passing through the fine needle at the rear end of the chip, the spinning solution is squeezed into the coagulation bath to form primary fibers. After solvent exchange in the coagulation bath, multiple primary fibers are stretched onto the first stretching roller. After being fully stretched between differential stretching rollers with a total stretching multiple of 4 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0037] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fiber were tested, and the test results are as follows: Figure 4 As shown, the stress is 401.1±26.5MPa and the strain is 41.3±8.5%. The antibacterial performance of the material reaches more than 50%.

[0038] Example 3 1) Silk degumming The silk was cut into sheets after the pupae were removed, and the silk was placed in a 0.05% sodium carbonate solution, and the degummed silk was rinsed with purified water and dried. After drying, the mass of the degummed silk was weighed, and the degumming rate was calculated to be 28.1%.

[0039] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 0.5% manganese chloride mass fraction and 5% calcium chloride mass fraction in the solvent. The specific data are as follows: 0.174g manganese chloride, 2.0g calcium chloride, 38.0g formic acid were weighed and stirred thoroughly to obtain a clear and transparent dissolving solution. 6g degummed silk was added to the dissolving solution and a spinning solution with a concentration of 13% was obtained after sufficient dissolution.

[0040] 3) Preparation of coagulation bath A coagulation bath with a volume ratio of 60% isopropanol and 2% glycerol was prepared.

[0041] 4) Spinning A 10-channel aluminum alloy chip is used, and a plunger pump is used as the power source to squeeze the spinning into the chip. After passing through the fine needle at the rear end of the chip, the spinning solution is squeezed into the coagulation bath to form primary fibers. After solvent exchange in the coagulation bath, multiple primary fibers are stretched onto the first stretching roller. After being fully stretched between differential stretching rollers with a total stretching multiple of 4.5 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0042] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fiber were tested, and the test results are as follows: Figure 5 As shown, the stress is 503.5±53.0MPa and the strain is 25.5±7.0%. The antibacterial performance of the material reaches more than 20%.

[0043] Example 4 1) Silk degumming The silk was cut into sheets after the pupae were removed, and the silk was placed in a 0.05% sodium carbonate solution, and the degummed silk was rinsed with purified water and dried. After drying, the mass of the degummed silk was weighed, and the degumming rate was calculated to be 28.3%.

[0044] 2) Spinning solution preparation The dissolving solution was prepared according to the proportion of 0.5% copper chloride mass fraction and 5% calcium chloride mass fraction in the solvent. The specific data are as follows: 0.186g of copper chloride, 1.7g of calcium chloride, and 32.1g of formic acid were weighed and stirred thoroughly to obtain a clear and transparent dissolving solution. 6g of degummed silk was added to the dissolving solution and a spinning solution with a concentration of 15% was obtained after sufficient dissolution.

[0045] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 60% and a glycerol concentration of 3% was prepared by volume.

[0046] 4) Spinning Using a 7-channel aluminum alloy chip and a microinjection pump as the power source, the spinning is squeezed into the chip. After passing through the fine needle at the rear end of the chip, the spinning solution is squeezed into the coagulation bath to form primary fibers. After the primary fibers are solvent exchanged in the coagulation bath, they are drawn onto the first stretching roller. After being fully stretched between differential stretching rollers with a total stretching multiple of 8.3 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller. The scanning electron microscope cross-section of the regenerated silk fibroin multifilament long fibers is shown in FIG. Figure 2 shown.

[0047] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fiber were tested, and the test results are as follows: Figure 6 As shown, the stress is 494.7±32.3MPa and the strain is 24.1±3.6%. The antibacterial property of the material reaches more than 99.99%.

[0048] Example 5 1) Silk degumming The silk was cut into sheets after the pupae were removed, and the silk was placed in a 0.05% sodium carbonate solution, and the degummed silk was rinsed with purified water and dried. After drying, the mass of the degummed silk was weighed, and the degumming rate was calculated to be 28.3%.

[0049] 2) Spinning solution preparation The dissolving solution is prepared according to the ratio of 0.5% mass fraction of magnesium chloride and 5% mass fraction of calcium chloride in the solvent, and a clear and transparent dissolving solution is obtained after sufficient stirring. The degummed silk is added to the dissolving solution, and a spinning solution with a concentration of 15% is obtained after sufficient dissolution.

[0050] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 60% and a glycerol concentration of 3% was prepared by volume.

[0051] 4) Spinning A 7-channel aluminum alloy chip is used, and a microinjection pump is used as the power source to squeeze the spinning into the chip. After passing through the fine needle at the rear end of the chip, the spinning solution is squeezed into the coagulation bath to form primary fibers. After solvent exchange in the coagulation bath, multiple primary fibers are stretched onto the first stretching roller. After being fully stretched between differential stretching rollers with a total stretching multiple of 6.5 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0052] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fiber were tested, and the test results are as follows: Figure 7 As shown, the stress is 598.9±29.7MPa and the strain is 27.8±6.7%.

[0053] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiments of the present invention can also be modified in various ways. All simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A method for preparing metal ion-reinforced antibacterial silk protein fiber, characterized in that: The following steps are involved: S1: degumming the silk in an alkaline salt solution, drying it naturally, and obtaining degummed silk; S2: preparing a dissolving solution containing transition metal ions, calcium ions and an organic solvent, dissolving the degummed silk in the dissolving solution to obtain a spinning solution of a certain concentration; the organic solvent is one or more of formic acid, hexafluoroisopropanol and trifluoroacetic acid, and the transition metal ions are Fe 3+ , Zn 2+ , Mn 2+ , Cu 2+ ,Mg 2+ One of the following; the concentration of the transition metal ion is 0.1-1.0%, and the concentration of the calcium ion is 1-10%; S3: The spinning solution is squeezed or sucked into the multi-channel spinning chip through a metering device; S4: The spinning solution is squeezed from the extrusion port through the chip into a coagulation bath containing a certain concentration of coagulant and toughening agent to form multiple strands of fiber fibrils; S5: After the multi-strand fiber fibrils come out of the coagulation bath, they are subjected to differential stretching between stretching rollers, and finally a metal ion-reinforced antibacterial silk protein fiber is obtained on a collecting roller.

2. The preparation method according to claim 1, characterized in that: In step S1, the concentration of the alkaline salt solution is 0.01%-1.00%.

3. The preparation method according to claim 1, characterized in that: In step S1, the solid-liquid mass ratio of the degumming is 1:10-1:1000, and the degumming lasts for 10-120 minutes.

4. The preparation method according to claim 1, characterized in that: In step S2, the concentration of transition metal ions in the used dissolving solution is 0.5%, and the concentration of calcium ions is 5%.

5. The preparation method according to claim 1, characterized in that: In step S2, the dissolving solution used contains 0.5% by mass of ferric chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

6. The preparation method according to claim 1, characterized in that: In step S2, the dissolving solution used contains 0.5% by mass of manganese chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

7. The preparation method according to claim 1, characterized in that: In step S4, the coagulation bath contains 50-60% ethanol and 3-5% glycerol by volume.

8. The preparation method according to claim 1, characterized in that: In step S5, the stretching multiple of the differential stretching is 4-10.

9. The preparation method according to claim 1, characterized in that: In step S1, the silk raw material is natural silk or waste silk obtained after natural silk cocoons are de-pupaed, and the natural silk cocoons are one or both of mulberry silk cocoons and tussah silk cocoons.

10. A metal ion-reinforced antibacterial silk protein fiber prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The metal ion enhanced antibacterial silk protein fiber has certain antibacterial properties and can effectively inhibit the growth and reproduction of microorganisms, including Escherichia coli and Staphylococcus aureus, with an antibacterial rate of ≥99.99%.

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