Rare earth ion reinforced silk protein fiber and preparation method thereof

Abstract

The invention discloses a rare earth ion reinforced silk protein fiber and a preparation method thereof. The preparation method comprises the following steps: S1, degumming silk in an alkaline salt solution to obtain degummed silk; s2, preparing a dissolving solution containing rare earth ions, calcium ions and an organic solvent, and dissolving the degummed silk in the dissolving solution to obtain a spinning solution with a certain concentration; s3, the spinning solution is squeezed into or sucked into a multi-channel spinning chip; s4, after the spinning solution is extruded through the chip, the spinning solution enters a coagulating bath to form multiple strands of fiber fibrils; s5, after the multiple strands of fibrils come out of the coagulating bath, differential stretching treatment is conducted through a stretching roller, and finally the rare earth ion reinforced silk protein fibers are obtained on a collecting roller. The rare earth ion reinforced silk protein fiber prepared according to the invention has excellent mechanical properties, excellent biocompatibility and degradability, and has a wide application prospect in the field of medicines.

Description

Technical Field

[0001] The invention relates to the technical field of biological protein fiber preparation, and in particular to a rare earth ion reinforced 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. 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 during 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 rare earth ion reinforced 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 object of the invention, the present invention provides the following technical solutions: According to a first aspect of the present invention, a method for preparing rare earth metal ion reinforced silk protein fiber is provided, comprising the following steps: S1: degumming silk in an alkaline salt solution to remove sericin to obtain pure silk fibroin fiber; S2: preparing a dissolving solution comprising rare earth 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; the source of the rare earth metal ions is chloride of the rare earth metal ions, and the rare earth The concentration of the chloride of the metal ion is 1.0-6.0%, and the source of the calcium ion is calcium chloride, and the concentration of the calcium chloride is 1-10%; S3: Use a metering device to squeeze or suck the spinning solution into a multi-channel spinning chip to ensure the uniform distribution of the spinning solution; S4: After the spinning solution is extruded through the chip, it enters a coagulation bath containing a certain concentration of coagulant and toughening agent to form multiple fiber fibrils; S5: After the multiple fiber fibrils come out of the coagulation bath, they are subjected to differential stretching treatment through a stretching roller, and finally a rare earth metal ion reinforced silk protein fiber is obtained on a collecting roller.

[0005] Preferably, in step S1, the silk raw material is natural silk obtained from natural silk cocoons or waste silk obtained after pupation, and the natural silk cocoons are one or both of mulberry silk cocoons and tussah silk cocoons, and mulberry silk cocoons are most preferred.

[0006] Preferably, in step S1, the solute of the alkaline salt solution is one or more of sodium carbonate and sodium bicarbonate, and the concentration of the alkaline salt solution is 0.01%-1.00%, and most preferably 0.05%.

[0007] In step S2, the rare earth metal ions include lanthanide elements (lanthanum, cerium, praseodymium, neodymium, etc.) and scandium and yttrium, a total of 16 elements (except the radioactive element promethium). It should be understood that according to the method provided by the present invention, the rare earth metal ion is any one of the 16 rare earth elements.

[0008] Preferably, in step S2, the source of the rare earth metal ions is chloride containing crystal water or chloride not containing crystal water.

[0009] Preferably, in step S2, the rare earth metal ions are in a dissolved state of being completely dissolved or incompletely dissolved.

[0010] Preferably, in step S2, the concentration of chloride of rare earth metal ions in the dissolving solution used is 1.0-3.0%, and the concentration of calcium chloride is 3.0-5.0%.

[0011] Preferably, in step S2, the dissolving solution used contains 1.0% by mass of lanthanum chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

[0012] Preferably, in step S4, the coagulation bath contains 50-60% ethanol and 2-5% glycerol by volume. Also preferably, the coagulation bath contains 50-60% isopropanol and 2-5% glycerol by volume.

[0013] Preferably, in step S5, the stretching ratio of the differential stretching is 4-10.

[0014] Preferably, the degumming lasts for a period of 10-120 min, most preferably 30 min.

[0015] Preferably, in step S2, the degummed silk fibroin fibers are dry degummed silk after natural drying; the degumming rate of the degummed silk fibroin fibers is 20%-35%, more preferably 25%-30%.

[0016] Preferably, the sources of the rare earth metal ions include chlorides containing water of crystallization and chlorides without water of crystallization, and more preferably anhydrous chlorides; the dissolution process is divided into two modes: complete dissolution and incomplete dissolution, and incomplete dissolution is preferred.

[0017] Preferably, in step S3, the metering device 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.

[0018] Preferably, in step S4, the coagulant of the coagulation bath is an alcohol substance such as ethanol, methanol, isopropanol, etc.; the concentration of the coagulant is 10%-90%, more preferably 50%-60%; the toughening agent of the coagulation bath is one or more of glycerol, ethyl acetate, ectoine, dioctyl phthalate, most preferably glycerol; the concentration of the toughening agent is 1%-10%, more preferably 2%-5%.

[0019] According to the present invention, in step S4 and step S5, 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 evaporates during the stretching process, and finally regenerated silk fibroin multifilament long fibers with certain mechanical properties are collected on the collecting roller.

[0020] According to a preferred embodiment of the present invention, a dissolving solution is prepared in which the mass fraction of cerium chloride in the solvent is 1% and the mass fraction of calcium chloride is 5%; a coagulation bath with a volume ratio of 60% isopropanol and 2% glycerol is prepared; after being fully stretched between differential stretching rollers with a total stretching ratio of 6.5 times, rare earth metal ion-reinforced silk protein fibers are collected on a collecting roller and mechanical properties are tested, and the stress is as high as 720.2±4.3MPa and the strain is 14.4±3.5%.

[0021] According to a most preferred embodiment of the present invention, a dissolving solution is prepared with a mass fraction of 1% lanthanum chloride and a mass fraction of 5% calcium chloride in the solvent, and a coagulation bath with a volume ratio of 50% ethanol concentration and 5% glycerol concentration is prepared. After being fully stretched between differential stretching rollers with a total stretching multiple of 6.5 times, rare earth metal ion-reinforced silk protein fibers are collected on a collection roller, and mechanical properties are tested, with a stress of up to 748.4±18.5MPa and a strain of 25.9±4.7%.

[0022] According to a second aspect of the present invention, there is provided a rare earth metal ion reinforced silk protein fiber prepared by the above method.

[0023] Preferably, the rare earth metal ion reinforced silk protein fiber is composed of a plurality of regenerated silk fibroin fiber monofilaments; the number of strands of the plurality of fiber fibrils is 2-500, more preferably 5-50; and the long fiber is a regenerated silk fibroin fiber with a length greater than 1000 m.

[0024] Preferably, the rare earth metal ion reinforced silk protein fiber prepared according to 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%.

[0025] It should be understood that in addition to fibers directly derived from animals and plants, the methods of 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 team of Zhang Yingying of Tsinghua University reported a method of preparing silk fibers with significantly improved strength and toughness by feeding silkworms with rare earth ions. Since this method is to feed silkworms with rare earth ions and synthesize silk through silkworm organisms, there is currently no evidence that most of the rare earth ions enter the silk or other parts of the silkworm's body. If there are rare earth ions in the silk, the content of rare earth ions in the silk is obviously uncontrollable, and the production of silk by silkworms alone has obvious defects of low yield and low efficiency, and it is impossible to achieve continuous preparation of silk. Therefore, this method has the disadvantages of low synthesis efficiency, poor controllability and inability to prepare continuously.

[0026] However, the present invention dissolves silk in a solution containing rare earth metal ions, calcium ions, and an organic solvent, and then extrude the spinning solution into a coagulation bath. After the fibers come out of the coagulation bath, they are oriented and shaped by post-stretching to obtain regenerated silk fibers with certain mechanical properties. By optimizing the process parameters of the spinning solution and the coagulation bath and doping with rare earth metal ions, regenerated silk protein fibers comparable to natural silk can be obtained. While optimizing the degradation performance, it also has positive significance for resource recycling and environmental protection.

[0027] The key invention of the present invention is mainly to dissolve silk by using organic solvents such as formic acid, and add calcium ions as a dissolution promoter, especially adding a certain amount of rare earth metal ions 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, which are coagulated into primary fibers with a certain solid morphology after solvent exchange in the coagulation bath. The primary fibers are differentially stretched between differential stretching rollers, and the solvent evaporates during the stretching process, and finally regenerated silk fibroin multifilament long fibers with certain mechanical properties are collected on a 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.

[0028] The rare earth metal ion reinforced silk protein fiber prepared according to the method of the present invention has excellent mechanical properties. The protein fiber has broad application prospects in the medical field due to its excellent biocompatibility and degradability, especially as an absorbable surgical suture, which can be gradually absorbed by the human body after the wound heals, without the need for secondary surgery to remove, thereby reducing the patient's pain and medical costs. In addition to surgical sutures, regenerated silk protein fibers can also be used to prepare other biomaterials, such as tissue engineering scaffolds, drug carriers, etc., providing more innovative options for the biomedical field. With the deepening of research on regenerated silk protein fibers, it is expected that more fiber materials with special properties and application value will be developed in the future. Since regenerated silk protein fibers have broad application prospects in many fields, their market potential is huge.

[0029] In summary, the present invention uses organic solvents such as formic acid, combines the dissolution-promoting and coordination-enhancing effects of calcium ions, and the structural-enhancing effects of rare earth metal ions, and can dissolve and spin silk in a one-step method, and wind up 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 both excellent mechanical properties and good degradability, and can be further applied in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 fiber stress-strain curve diagram of Example 1 of the present invention; Figure 3 is a fiber stress-strain curve diagram of Example 2 of the present invention; Figure 4 is a fiber stress-strain curve diagram of Example 3 of the present invention; Figure 5 is a fiber stress-strain curve diagram of Example 4 of the present invention; Figure 6 is a fiber stress-strain curve diagram of Example 5 of the present invention; Figure 7 This is a fiber stress-strain curve diagram of Example 6 of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] Example 1 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 26.9%.

[0033] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 0.5% mass fraction of lanthanum chloride and 5% mass fraction of calcium chloride in the solvent, and after being fully stirred for half an hour, an incompletely dissolved suspension was obtained. The degummed silk was added to the suspension, and after being fully dissolved, a spinning solution with a concentration of 13% was obtained.

[0034] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0035] 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 6.5 times, and then regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0036] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 2 As shown, each line of different colors represents a different sample, where the stress is 687.1±4.5MPa and the strain is 18.9±1.9%.

[0037] Example 2 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 25.7%.

[0038] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 1% by mass of lanthanum chloride and 5% by mass of calcium chloride in the solvent, and after being fully stirred for half an hour, an incompletely dissolved suspension was obtained. The degummed silk was added to the suspension, and after being fully dissolved, a spinning solution with a concentration of 13% was obtained.

[0039] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0040] 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 6.5 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0041] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 3 As shown, each line of different colors represents a different sample, where the stress is 748.4±18.5MPa and the strain is 25.9±4.7%.

[0042] 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 26.3%.

[0043] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 2% by mass of lanthanum chloride and 5% by mass of calcium chloride in the solvent, and after being fully stirred for half an hour, an incompletely dissolved suspension was obtained. The degummed silk was added to the suspension, and after being fully dissolved, a spinning solution with a concentration of 13% was obtained.

[0044] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0045] 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 6.5 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0046] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 4 As shown, each line of different colors represents a different sample, where the stress is 640.8±9.4MPa and the strain is 17.7±0.8%.

[0047] 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 27.5%.

[0048] 2) Spinning solution preparation The dissolving solution is prepared according to the ratio of 1% mass fraction of lanthanum chloride and 5% mass fraction of calcium chloride in the solvent, and a completely dissolved dissolving solution is obtained after sufficient stirring. The degummed silk is added to the clear and transparent dissolving solution, and a spinning solution with a concentration of 13% is obtained after sufficient dissolution.

[0049] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0050] 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 6 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0051] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 5 As shown, each line of different colors represents a different sample, where the stress is 576.6±18.6MPa and the strain is 24.3±5.6%.

[0052] Example 5 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 26.6%.

[0053] 2) Spinning solution preparation The dissolving solution was prepared according to the ratio of 1% cerium chloride mass fraction and 5% calcium chloride mass fraction in the solvent, and the suspension solution which was not completely dissolved was obtained after stirring for half an hour. The degummed silk was added to the suspension solution, and the spinning solution with a concentration of 15% was obtained after the degummed silk was fully dissolved.

[0054] 3) Preparation of coagulation bath A coagulation bath with a volume ratio of 60% isopropanol and 2% glycerol was prepared.

[0055] 4) Spinning A 10-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.

[0056] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 6 As shown, each line of different colors represents a different sample, where the stress is 720.2±4.3MPa and the strain is 14.4±3.5%.

[0057] Example 6 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 27.7%.

[0058] 2) Spinning solution preparation The dissolving solution is prepared according to the ratio of 1% praseodymium chloride mass fraction and 5% calcium chloride mass fraction 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.

[0059] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 60% and a glycerol concentration of 3% was prepared by volume.

[0060] 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 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0061] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament were tested, and the results were as follows: Figure 7 As shown, each line of different colors represents a different sample, where the stress is 495.1±17.8MPa and the strain is 23.4±5.4%.

[0062] Example 7 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 27.5%.

[0063] 2) Spinning solution preparation The dissolving solution was prepared according to the mass fraction of lanthanum chloride and calcium chloride in the solvent, which were 0%, 6%; 1%, 5%; 2%, 4%; 3%, 3%; 6%, 0%, respectively, and a completely dissolved dissolving solution was obtained after sufficient stirring. The degummed silk was added to the clear and transparent dissolving solution, and a spinning solution with a concentration of 13% was obtained after sufficient dissolution.

[0064] 3) Preparation of coagulation bath A coagulation bath with an ethanol concentration of 50% and a glycerol concentration of 5% was prepared by volume.

[0065] 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 6 times, regenerated silk fibroin multifilament long fibers with a certain stress strain are obtained on the collecting roller.

[0066] 5) Test characterization The mechanical properties of the obtained regenerated silk fibroin multifilament fibers were tested, and the stress was shown in Table 1.

[0067] Table 1 Different rare earth La 3+ With Ca 2+ Mechanical properties of fibers prepared by ratio .

[0068] 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 rare earth ion reinforced silk protein fiber, characterized in that: The following steps are involved: S1: degumming the silk in an alkaline salt solution to remove sericin to obtain degummed silk; S2: preparing a dissolving solution containing rare earth ions, calcium ions and an organic solvent, and 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; the source of the rare earth ions is chloride of rare earth ions, the concentration of the chloride of rare earth ions is 1.0-6.0%, the source of the calcium ions is calcium chloride, the concentration of the calcium chloride is 1-10%; S3: using a metering device to squeeze or suck the spinning solution into the multi-channel spinning chip to ensure uniform distribution of the spinning solution; S4: After the spinning solution is extruded through the chip, it enters a coagulation bath containing a certain concentration of coagulant and toughening agent to form multiple strands of fiber fibrils; S5: After the plurality of fiber fibrils come out of the coagulation bath, they are subjected to differential stretching treatment by stretching rollers, and finally a rare earth ion reinforced silk protein fiber is obtained on a collecting roller.

2. 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.

3. The preparation method according to claim 1, characterized in that: In step S1, the solute of the alkaline salt solution is one or more of sodium carbonate and sodium bicarbonate, and the concentration of the alkaline salt solution is 0.01%-1.00%.

4. The preparation method according to claim 1, characterized in that: In step S2, the source of the rare earth ions is chloride containing crystal water or chloride not containing crystal water.

5. The preparation method according to claim 1, characterized in that: In step S2, the rare earth ions are in a dissolved state of being completely dissolved or incompletely dissolved.

6. The preparation method according to claim 1, characterized in that: In step S2, the concentration of chloride of rare earth ions in the dissolving solution used is 1.0-3.0%, and the concentration of calcium chloride is 3.0-5.0%.

7. The preparation method according to claim 1, characterized in that: In step S2, the dissolving solution used contains 1.0% by mass of lanthanum chloride, 5% by mass of calcium chloride, and the organic solvent is formic acid.

8. The preparation method according to claim 1, characterized in that: In step S4, the coagulation bath contains 50-60% ethanol and 2-5% glycerol by volume.

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

10. A rare earth ion reinforced silk protein fiber prepared by the preparation method according to any one of claims 1 to 9.

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