High-strength nanocomposite screw material based on concentric fiber barrel structure and preparation method thereof

Abstract

The application discloses a high-strength nanometer composite screw material based on a concentric fiber cylinder structure and a preparation method thereof. Specifically, 1) first, a PLGA fiber cylinder material with a diameter gradient is woven; 2) using an in-situ mineralization process, hydroxyapatite is mineralized on the surface of graphene oxide to obtain a GO / HA nanofiller, and a cold explosion method is used to prepare an alkali-dissolved chitosan / cellulose mixed solution which is compounded with the GO / HA, and the solution is defoamed through low-speed centrifugation; 3) the fiber cylinder is concentrically sleeved and fixed in an open cylinder mold, the above solution is cast on the wall of the mold, and the mold is transferred to a 60-80 DEG C condition for in-situ gelation; 4) after dialysis, the mold is transferred to a rotary drying device for drying and dehydration, and the required high-strength nanometer composite screw material is obtained after turning according to a drawing. The screw material adopts the GO / HA filler which has high dispersity and the concentric fiber cylinder structure for reinforcement, and the HA can promote osteogenesis, so that the screw strength and bioactivity requirements are met.

Description

Technical Field

[0001] The present invention relates to a preparation technology of a bone repair material, and in particular to a high-strength nano-composite screw material based on a concentric fiber tube structure and a preparation method thereof. Background Art

[0002] Screws are internal fixation devices that can be used to fix fracture sites. They are generally used alone or in combination with bone plates in clinical practice. Metal screws are currently the most commonly used materials, but due to stress shielding, the need for secondary surgery, and the susceptibility to inflammation, patients may experience discomfort or a huge physical / psychological burden during use. In response to the shortcomings of current metal materials, scientists have developed a variety of new degradable screw materials in recent years, such as hydroxyapatite screws and polylactic acid screws, which can be degraded in the body after implantation, effectively reducing the pain caused to patients by secondary surgery. Since the development of degradable screws is still in its early stages and related technologies are not yet mature, problems such as the brittle fracture of hydroxyapatite screws and the lack of biological activity of polylactic acid screws still need to be urgently addressed.

[0003] To address the above issues, the present invention is inspired by the tree ring structure: after a tree is felled, many concentric rings can be seen on the stump, which are called annual rings in botany. Annual rings are formed by the tree during its growth process, influenced by the seasons, with one ring produced each year. Due to the existence of the annual ring structure, the bending strength of the tree is very excellent, and it can withstand forces such as strong winds. Therefore, if this structure is introduced into the screw, can it be strengthened? Secondly, hydroxyapatite has a very good effect on promoting bone formation, but because it is prone to agglomeration and poor dispersion in the polymer matrix, the amount of its nanocomposite addition is limited. GO, as a new type of nanofiller with a large number of oxygen-containing functional groups on its surface, has good dispersion properties in water, and the large number of oxygen-containing functional groups can serve as nucleation sites for hydroxyapatite. Therefore, if GO can be used as the core and hydroxyapatite can be composited on its surface to prepare a new nanofiller with high dispersibility and osteogenic activity, it will have a huge driving force for the functional upgrading of screws.

[0004] Therefore, this paper proposes a high-strength nanocomposite screw material based on a concentric fiber cylinder structure and its preparation method. By preparing a concentric fiber cylinder to simulate the structure of concentric growth rings, and simultaneously preparing GO / HA nanofillers, the screw is reinforced and endowed with osteogenic activity, providing a new strategy for screw upgrades. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength nanocomposite screw material based on a concentric fiber tube structure and a preparation method thereof to address the problems of poor mechanical strength and insignificant osteogenic activity of traditional bone repair hydrogels.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure, comprising:

[0008] 1) First, weave a polylactic-co-glycolic acid (PLGA) fiber cylindrical material with different diameter gradients;

[0009] 2) Using an in situ mineralization process to mineralize hydroxyapatite on the surface of graphene oxide (GO) to obtain GO / HA nanofillers, and simultaneously using a freeze-blast method to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA, followed by low-speed centrifugation for degassing;

[0010] 3) Fiber cylinders of different diameters are concentrically arranged and fixed in an open cylindrical mold. The above solution is poured onto the wall and the mold is transferred to a temperature of 60-80°C for in-situ gelation.

[0011] 4) After dialysis, the product is transferred to a rotary drying device for drying and dehydration, and then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

[0012] Furthermore, in step 1), the diameter of the fiber cylinders is 3-49 mm, and they are arranged at equal intervals from small to large, and the number of fiber cylinders is 3-15.

[0013] Furthermore, in the step 2), the in-situ mineralization process is to add GO to a surface mineralization solution, wherein the diameter of the GO is about 3-6 microns and the concentration is 0.01-0.08 wt%; the surface mineralization solution formula is: sodium chloride 50-70 mM, disodium hydrogen phosphate 20-30 mM, potassium chloride 60-100 mM, potassium hydrogen phosphate 5-10 mM, magnesium sulfate 0.4-0.75 mM, magnesium chloride 0.8-1.2 mM, calcium chloride 4-6 mM, sodium bicarbonate 0.2-0.4 mM, dicalcium hydrogen phosphate 0.4-0.6 mM, sodium sulfate 0.025-0.05 mM, HEPES 13-25 mM, and the solvent is deionized water; the mineralization temperature is 35-37 ° C, the mineralization time is 1-7 days, and the stirring rate is 30-60 r / min;

[0014] Furthermore, the alkali-soluble chitosan / cellulose solution is formulated as follows: a total chitosan and cellulose concentration of 4-10wt%, GO / HA 0.5-10wt%, urea 5-7wt%, lithium hydroxide monohydrate 7-10wt%, and the remainder deionized water. The chitosan has a molecular weight of 1-2 million, a degree of deacetylation of 70-80%, and the cellulose has a molecular weight of 1-2 million. The freeze-blast method involves stirring and swelling the solution for 30-60 minutes, freezing it at -20-80°C, and then chipping the ice until it completely melts. This process is repeated 3-5 times to obtain a completely dissolved alkali-soluble chitosan / cellulose mixed solution. The low-speed centrifugal degassing process is performed at a speed of 1000-1500 rpm for 5-15 minutes.

[0015] Furthermore, in step 3), the diameter of the open cylindrical mold is 2-5 cm and the height is 5-10 cm. A hook is provided on the lower base for fixing the lower end of the fiber tube, and a bracket is provided on the upper end for fixing the upper end of the fiber tube. The in situ gelation time is 1-3 hours, and deionized water is added to the gel every 30 minutes during the gelation process.

[0016] Furthermore, the rotary drying equipment in step 4) is structured as follows: the heating and drying assembly comprises two parallel, counter-rotating heating screws, each of which is provided with a stainless steel cylinder having fine holes therein. The screw speed is 20-50 rpm, and the heating temperature is 50-80°C.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1) The present invention uses chitosan, cellulose, GO, HA, PLGA fibers, etc. as raw materials, and combines fiber weaving, in-situ casting, thermal gelation, nanocomposite, rotary drying and turning to produce a high-strength nanocomposite screw material based on a concentric fiber tube structure. The above raw material selection and process combination are original to the present invention.

[0019] 2) In the present invention, nanocomposite and wood-like concentric annual ring reinforcement strategies are introduced. Firstly, GO is used as the core to in-situ mineralize HA layer on its surface, obtaining GO / HA nanofiller, which retains the high dispersibility of GO in water; when GO / HA nanofiller is compounded into the interior of chitosan / cellulose matrix, the polymer matrix can be reinforced. On the other hand, a fiber cylinder with a concentric structure is used, and the fiber cylinder is uniformly fixed in the polymer matrix by in-situ pouring process to form a wood-like concentric annual ring structure for screw reinforcement; wherein the fiber cylinder with different radii is fixed in the mold to form a concentric structure similar to the annual ring, and when the pouring solution is poured, the solution penetrates into the interior of the fiber cylinder, and after gelation, good penetration and mechanical occlusion are formed. When the screw is subjected to bending stress, the nanocomposite filler reinforces the entire matrix, and the internal concentric fiber cylinder inhibits the development of cracks by fiber pull-out reinforcement mechanism when the polymer matrix begins to deform, thereby achieving the purpose of screw reinforcement. The above up-punch reinforcement strategy is the first of its kind.

[0020] 3) In the present invention, open cylinder mold + fiber cylinder fixed arrangement technology + in-situ pouring and curing process are used to realize nanocomposite screw materials with concentric fiber cylinder structure. Since the concentric fiber cylinder structure is designed in the present invention, an open cylinder mold is introduced to fix the upper and lower ends of the fiber cylinder, so that it can be fixed and arranged according to the diameter size, laying the foundation for the subsequent formation of wood-like concentric annual ring structure; then, through the in-situ pouring process, the chitosan / cellulose solution is poured into the mold by adhesion, and the mold is completely filled through the flow and penetration of the solution, and at the same time the fiber cylinder is wrapped by the polymer solution, and the fixed arrangement of the fiber cylinder is not damaged; finally, under the action of the heating in-situ curing process, the polymer solution is successfully gelled, obtaining the first stage form of the screw. According to the structure of the composite screw and the actual preparation needs, the above combined process is carefully designed, realizing the new application of the old process, so as to finally obtain the required composite screw.

[0021] 4) The present invention combines the combined processes of in-situ pouring gelation + rotary drying + turning, so that the screw undergoes three forms of hydrogel-rod-screw in sequence, and finally obtains the required high-strength nano-composite screw material based on the concentric fiber tube structure. First, through the in-situ pouring gelation process, a composite hydrogel material with a fixedly arranged fiber cylinder embedded inside is obtained; through rotary drying, the moisture inside the gel is gradually removed. At the same time, the special rotary drying device of the present invention can ensure that the moisture on the surface of the hydrogel is evenly removed, so that the obtained composite rod remains straight. If the hydrogel is directly dried, a curved rod will be obtained, which cannot be subsequently turned; finally, the present invention combines the traditional turning process to form the required thread structure on the surface of the straight rod, and finally forms the required composite screw material. It is the organic synergy of the above-mentioned combined processes that makes it possible to successfully prepare the screws required by the present invention. Behind the seemingly simple process is the applicant's careful coordination and cooperation of the material structure and the preparation process, realizing a new application of the combination of traditional processes.

[0022] 5) The screws in the present invention have high biocompatibility, biodegradability, high bending strength, and osteopromoting properties, meeting the complex use requirements of the screws. The raw materials used in the present invention are all highly biocompatible and biodegradable, so the composite screws are non-toxic during subsequent use and can be degraded in the body, thereby helping patients get rid of the trouble of secondary surgery; the nano-composite and the wood-like concentric annual ring structure constructed using fiber cylinders are used to enhance the screws, so that the screws have excellent bending strength and meet the mechanical requirements of the screws when used in the body; and in the present invention, GO is used as the core and an HA coating is in situ mineralized on its surface to form a GO / HA nanofiller. Due to the high dispersibility of GO in water, the amount of GO / HA added can be significantly increased compared to HA, which is closer to the HA content of natural bone, thereby showing excellent osteopromoting properties. It is precisely because of the organic synergistic effect between the above functions that the composite screws can meet complex usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the preparation process of high-strength nanocomposite screw materials based on concentric fiber tube structure. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific examples. Figure 1The figure shows a schematic diagram of the preparation process of the screw material of the present invention. In a specific embodiment, the working process of the rotary drying device is as follows: two heated screws are at the bottom and the screws can rotate; then a stainless steel cylinder with fine holes is placed above the two screws and parallel to the screws, and the sample is placed inside the stainless steel cylinder parallel to the direction of the stainless steel cylinder. The stainless steel cylinder is driven by the rotation of the screws, and the fine holes on the stainless steel cylinder are used to discharge water vapor.

[0025] Comparative Example 1:

[0026] 1) GO / HA nanofillers were obtained by mineralizing hydroxyapatite on the surface of GO using an in situ mineralization process. The mineralization solution was as follows: 50 mM sodium chloride, 30 mM disodium hydrogen phosphate, 100 mM potassium chloride, 5 mM potassium hydrogen phosphate, 0.6 mM magnesium sulfate, 0.9 mM magnesium chloride, 5 mM calcium chloride, 0.2 mM sodium bicarbonate, 0.4 mM dicalcium hydrogen phosphate, 0.05 mM sodium sulfate, and 18 mM HEPES. The solvent was deionized water. The mineralization temperature was 37°C, the mineralization time was 3 days, and the stirring rate was 30 r / min. At the same time, a freeze-blast method (the solution was stirred and swollen for 30 minutes, then frozen at -20°C, and then ice was chipped until the ice was completely melted, and the above process was repeated 4 times) was used to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA (the solution contained 4 wt% chitosan, 4 wt% cellulose, 0.8 wt% GO / HA, 6 wt% urea, 8 wt% lithium hydroxide monohydrate, and the remainder was deionized water, wherein the chitosan had a molecular weight of 1 million and a degree of deacetylation of 80%, and the cellulose had a molecular weight of 1.8 million). The solution was degassed by low-speed centrifugation (1000 rpm for 5 minutes).

[0027] 2) The above solution was poured into the mold and transferred together with the mold to 60°C for in-situ gelation (the in-situ gelation time was 2 hours, and deionized water was added to the gel every 30 minutes during the gelation process);

[0028] 4) After complete dialysis with deionized water, the product was transferred to a rotary drying apparatus (the heating and drying assembly of which consisted of two parallel, counter-rotating heating screws, each of which contained a stainless steel cylinder with fine pores) for drying and dehydration (screw speed: 30 r / min, heating temperature: 60°C). The product was then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

[0029] First, an extract of the aforementioned material was prepared and co-cultured with bone marrow mesenchymal stem cells (BMSCs) for 7 days. CCK-8 assays demonstrated a cell survival rate of approximately 92.8% and a flexural strength of approximately 224.6 MPa. ALP activity was measured after 14 days of co-culture with BMSCs, revealing an ALP activity of approximately 375.8 u / g protein.

[0030] Example 1:

[0031] 1) First, weave PLGA fiber cylinder materials with different diameter gradients (minimum diameter 3 mm, maximum diameter 19 mm, interval 4 mm, number of 5);

[0032] 2) GO / HA nanofillers were obtained by mineralizing hydroxyapatite on the GO surface using an in situ mineralization process. The mineralization solution was as follows: 50 mM sodium chloride, 30 mM disodium hydrogen phosphate, 100 mM potassium chloride, 5 mM potassium hydrogen phosphate, 0.6 mM magnesium sulfate, 0.9 mM magnesium chloride, 5 mM calcium chloride, 0.2 mM sodium bicarbonate, 0.4 mM dicalcium hydrogen phosphate, 0.05 mM sodium sulfate, and 18 mM HEPES. The solvent was deionized water. The mineralization temperature was 37°C, the mineralization time was 3 days, and the stirring rate was 30 r / min. At the same time, a freeze-blast method (the solution was stirred and swollen for 30 minutes, then frozen at -20°C, and then ice-chipped until the ice was completely melted, and the above process was repeated 4 times) was used to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA (chitosan 4wt%, cellulose 4wt%, GO / HA 0.8wt%, urea 6wt%, lithium hydroxide monohydrate 8wt%, and the remainder was deionized water, wherein the chitosan had a molecular weight of 1 million and a degree of deacetylation of 80%, and the cellulose had a molecular weight of 1.8 million). The solution was degassed by low-speed centrifugation (1000 rpm for 5 minutes).

[0033] 3) The upper and lower ends of the fiber cylinder were fixed to an open cylindrical mold (2 cm in diameter and 10 cm in height, with a hook on the lower base for fixing the lower end of the fiber cylinder and a bracket on the upper base for fixing the upper end of the fiber cylinder). The above solution was poured onto the bracket and the hook on the base. The mold was transferred to an in situ gelation at 60°C (the in situ gelation time was 2 hours, and the gel was supplemented with deionized water every 30 minutes during the gelation process).

[0034] 4) After complete dialysis with deionized water, the product was transferred to a rotary drying apparatus (the heating and drying assembly consisted of two parallel, counter-rotating heating screws, each of which was fitted with a stainless steel cylinder with fine pores) for drying and dehydration (screw speed: 30 r / min, heating temperature: 60°C). The product was then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

[0035] Compared to Comparative Example 1, this example incorporates a concentric fiber tube structure. First, an extract of the aforementioned material was prepared. After co-culturing with BMSCs for 7 days, CCK-8 assay results indicated a cell survival rate of approximately 92.3% and a flexural strength of approximately 426.5 MPa. ALP activity was measured after 14 days of co-culturing with BMSCs, revealing an ALP activity of approximately 358.1 u / g protein.

[0036] Example 2:

[0037] 1) First, weave PLGA fiber cylinder materials with different diameter gradients (minimum diameter 3 mm, maximum diameter 17 mm, interval 7 mm, number of 3);

[0038] 2) GO / HA nanofillers were obtained by mineralizing hydroxyapatite on the GO surface using an in situ mineralization process. The mineralization solution was as follows: 50 mM sodium chloride, 30 mM disodium hydrogen phosphate, 100 mM potassium chloride, 5 mM potassium hydrogen phosphate, 0.6 mM magnesium sulfate, 0.9 mM magnesium chloride, 5 mM calcium chloride, 0.2 mM sodium bicarbonate, 0.4 mM dicalcium hydrogen phosphate, 0.05 mM sodium sulfate, and 18 mM HEPES. The solvent was deionized water. The mineralization temperature was 37°C, the mineralization time was 3 days, and the stirring rate was 30 r / min. At the same time, a freeze-blast method (the solution was stirred and swollen for 30 minutes, then frozen at -20°C, and then ice-chipped until the ice was completely melted, and the above process was repeated 4 times) was used to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA (chitosan 4wt%, cellulose 4wt%, GO / HA 0.8wt%, urea 6wt%, lithium hydroxide monohydrate 8wt%, and the remainder was deionized water, wherein the chitosan had a molecular weight of 1 million and a degree of deacetylation of 80%, and the cellulose had a molecular weight of 1.8 million). The solution was degassed by low-speed centrifugation (1000 rpm for 5 minutes).

[0039] 3) The upper and lower ends of the fiber cylinder were fixed to an open cylindrical mold (2 cm in diameter and 10 cm in height, with a hook on the lower base for fixing the lower end of the fiber cylinder and a bracket on the upper base for fixing the upper end of the fiber cylinder). The above solution was poured onto the bracket and the hook on the base. The mold was transferred to an in situ gelation at 60°C (the in situ gelation time was 2 hours, and the gel was supplemented with deionized water every 30 minutes during the gelation process).

[0040] 4) After complete dialysis with deionized water, the product was transferred to a rotary drying apparatus (the heating and drying assembly consisted of two parallel, counter-rotating heating screws, each of which was fitted with a stainless steel cylinder with fine pores) for drying and dehydration (screw speed: 30 r / min, heating temperature: 60°C). The product was then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

[0041] Compared to Example 1, this example reduced the number and density of PLGA fiber tubes. First, an extract of the aforementioned material was prepared and co-cultured with BMSCs for 7 days. CCK-8 assay results indicated a cell viability of approximately 90.6% and a flexural strength of approximately 341.1 MPa. ALP activity was measured after 14 days of co-culture with BMSCs, revealing an ALP activity of approximately 325.6 u / g protein.

[0042] Example 3:

[0043] 1) First, weave PLGA fiber cylinder materials with different diameter gradients (minimum diameter 3 mm, maximum diameter 19 mm, interval 4 mm, number of 5);

[0044] 2) GO / HA nanofillers were obtained by mineralizing hydroxyapatite on the GO surface using an in situ mineralization process. The mineralization solution was as follows: 50 mM sodium chloride, 30 mM disodium hydrogen phosphate, 100 mM potassium chloride, 5 mM potassium hydrogen phosphate, 0.6 mM magnesium sulfate, 0.9 mM magnesium chloride, 5 mM calcium chloride, 0.2 mM sodium bicarbonate, 0.4 mM dicalcium hydrogen phosphate, 0.05 mM sodium sulfate, and 18 mM HEPES. The solvent was deionized water. The mineralization temperature was 37°C, the mineralization time was 7 days, and the stirring rate was 30 r / min. At the same time, a freeze-blast method (the solution was stirred and swollen for 30 minutes, then frozen at -20°C, and then ice-chipped until the ice was completely melted, and the above process was repeated 4 times) was used to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA (chitosan 4wt%, cellulose 4wt%, GO / HA 8wt%, urea 6wt%, lithium hydroxide monohydrate 8wt%, and the remainder was deionized water, wherein the chitosan had a molecular weight of 1 million and a degree of deacetylation of 80%, and the cellulose had a molecular weight of 1.8 million). The solution was degassed by low-speed centrifugation (1000 rpm for 5 minutes).

[0045] 3) The upper and lower ends of the fiber cylinder were fixed to an open cylindrical mold (2 cm in diameter and 10 cm in height, with a hook on the lower base for fixing the lower end of the fiber cylinder and a bracket on the upper base for fixing the upper end of the fiber cylinder). The above solution was poured onto the bracket and the hook on the base. The mold was transferred to an in situ gelation at 60°C (the in situ gelation time was 2 hours, and the gel was supplemented with deionized water every 30 minutes during the gelation process).

[0046] 4) After complete dialysis with deionized water, the product was transferred to a rotary drying apparatus (the heating and drying assembly consisted of two parallel, counter-rotating heating screws, each of which was fitted with a stainless steel cylinder with fine pores) for drying and dehydration (screw speed: 30 r / min, heating temperature: 60°C). The product was then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

[0047] Compared to Example 1, this example increased the mineralization time of GO / HA and the amount added to the polymer solution. First, an extract of the aforementioned material was prepared and co-cultured with BMSCs for 7 days. CCK-8 assay results showed a cell viability of approximately 88.6% and a screw bending strength of approximately 453.5 MPa. ALP activity was measured after 14 days of co-culture with BMSCs, revealing an ALP activity of approximately 424.2 u / g protein.

Claims

1. A method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure, characterized by: The following steps are involved: 1) First, weave a polylactic-co-glycolic acid (PLGA) fiber cylindrical material with different diameter gradients; 2) Using an in situ mineralization process to mineralize hydroxyapatite on the surface of graphene oxide (GO) to obtain GO / HA nanofillers, and simultaneously using a freeze-blast method to prepare an alkali-soluble chitosan / cellulose mixed solution composited with GO / HA, followed by low-speed centrifugation for degassing; 3) Concentrically nesting fiber cylinders of different diameters, each fixed in an open cylindrical mold, pouring the above solution onto the wall, and transferring the mold together to 60-80°C for in-situ gelation; 4) After dialysis, the product is transferred to a rotary drying device for drying and dehydration, and then turned according to the drawing to obtain the desired high-strength nanocomposite screw material.

2. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: In step 1), the diameter of the fiber cylinders is 3-49 mm, and they are arranged at equal intervals from small to large. The number of fiber cylinders is 3-15.

3. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: The in-situ mineralization process in step 2) is to add GO to the surface mineralization solution, wherein the diameter of GO is 3-6 microns and the concentration is 0.01-0.08wt%; the mineralization temperature is 35-37°C, the mineralization time is 1-7 days, and the stirring rate is 30-60r / min.

4. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 3, characterized in that: The surface mineralization solution has the following formula: sodium chloride 50-70mM, disodium hydrogen phosphate 20-30mM, potassium chloride 60-100mM, potassium hydrogen phosphate 5-10mM, magnesium sulfate 0.4-0.75mM, magnesium chloride 0.8-1.2mM, calcium chloride 4-6mM, sodium bicarbonate 0.2-0.4mM, dicalcium hydrogen phosphate 0.4-0.6mM, sodium sulfate 0.025-0.05mM, HEPES 13-25mM, and the solvent is deionized water.

5. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: The freeze-blasting method comprises stirring and swelling an alkali-soluble chitosan / cellulose solution containing GO / HA nanofillers for 30-60 minutes, freezing it at -20-80°C, and then chilling it until the ice is completely melted. The above process is repeated 3-5 times to obtain a completely dissolved alkali-soluble chitosan / cellulose mixed solution.

6. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 5, characterized in that: The alkali-soluble chitosan / cellulose solution has a formula of: a total concentration of chitosan and cellulose of 4-10wt%, GO / HA of 0.5-10wt%, urea of ​​5-7wt%, lithium hydroxide monohydrate of 7-10wt%, and the remainder of deionized water. The chitosan has a molecular weight of 1-2 million, a degree of deacetylation of 70-80%, and the cellulose has a molecular weight of 1-2 million.

7. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: The low-speed centrifugal degassing process is: the speed is 1000-1500rpm, and the time is 5-15min.

8. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: In step 3), the diameter of the open cylindrical mold is 2-5 cm and the height is 5-10 cm; the in-situ gelation time is 1-3 hours, and deionized water is added to the gel every 30 minutes during the gelation process.

9. The method for preparing a high-strength nanocomposite screw material based on a concentric fiber tube structure according to claim 1, characterized in that: The structure of the rotary drying equipment in step 4) is as follows: the heating and drying component is two parallel heating screws arranged side by side and capable of rotating in opposite directions. A stainless steel cylinder with fine holes is placed above the two screws for placing the sample to be dried. The screw speed is 20-50 r / min and the heating temperature is 50-80°C.

10. A high-strength nanocomposite screw material based on a concentric fiber tube structure, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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