CN112376143A

CN112376143A - Implantable ligament substitute material based on oriented carbon nanotube fibers and preparation method thereof

Info

Publication number: CN112376143A
Application number: CN202011150217.2A
Authority: CN
Inventors: 陈培宁; 解松林; 徐一帆; 赵天成; 万方; 彭慧胜
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2021-02-19
Anticipated expiration: 2040-10-23
Also published as: CN112376143B

Abstract

The invention belongs to the field of medical materials, and particularly relates to an implantable ligament substitute material based on oriented carbon nanotube fibers and a preparation method thereof. The invention takes the oriented carbon nanotube fiber as the basis, and obtains the double-helix fiber as the ligament implantation material through multi-strand fiber multi-stage helix and stress release. The ligament material obtained by the invention has the tensile modulus of 1.4-4GPa and the elongation at break of 10-30 percent, and can meet the mechanical requirements of implanted ligaments; the density is 0.3-0.9g/cm³And has a large number of nano-scale and micro-scale oriented pores similar to the autologous ligament structure. ThroughAfter the anterior cruciate ligament reconstruction operation is implanted into a new Zealand rabbit ligament defect model for 4 weeks, the regenerated bone grows into the gap between the ligament and the bone pore canal, and after 13 weeks, the regenerated bone is fused between the multilevel fiber pore canals, so that the implanted ligament and the bone tissue are completely integrated. The implantable ligament material can be used for ligament substitute implantation of animals such as mice, rabbits, cats, dogs, sheep, pigs, human beings and the like.

Description

Implantable ligament substitute material based on oriented carbon nanotube fibers and preparation method thereof

Technical Field

The invention belongs to the technical field of medical materials, and particularly relates to an implantable ligament substitute material based on oriented carbon nanotube fibers and a preparation method thereof.

Background

Dense connective tissue is a key tissue for connecting bones with bones and between bones and muscles, and is a key for realizing motor functions of a human body. Taking the anterior cruciate ligament as an example, the human body relies on tens of thousands of bends in one day of movement of the anterior cruciate ligament. In the reciprocating motion, the ligament always keeps the stress state or the stretching state, and the motion injury is not fresh. Along with the development of comprehensive body-building exercises and the improvement of the exercise attention degree of the nations, the movement injuries related to ligaments are continuously increased. After ligament rupture, reconstructive surgery is the best option. Statistically, one person per 1250 persons per year needs to undergo anterior cruciate ligament reconstruction surgery. The graft for reconstruction has three choices of autologous tendon, allogeneic tendon and artificial ligament. However, the use of autologous tendons can cause damage to the donor area, and the donor area cannot be regenerated after being cut, so that the source is limited, and the operation time is prolonged; the use of allogeneic tendons is also limited in source, requires a longer recovery period, and risks of disease transmission and immunological rejection. Autologous and allogeneic tendons also undergo lengthy "ligamentization" processes such as necrosis of transplanted cells and ingrowth of autologous cells and collagen remodeling. Compared with autologous and allogeneic tendon grafts, the artificial ligament can not cause donor area damage and infectious diseases, has sufficient sources, and can not obviously reduce the mechanical strength after transplantation. And the patient using the artificial ligament has a short return exercise time. Therefore, artificial ligaments have gained increasing attention.

The most widely used artificial Ligament in clinical practice is the LARS artificial Ligament (growth Advanced repair System) designed and developed by french scholars JP Laboureau, the main material of which is polyethylene terephthalate (PET). The LARS ligament can satisfy the mechanical requirements of the ligament, but cannot induce the growth of autologous tissues due to lack of biological activity in the long-term use process, so as to realize the integration with the surrounding bone tissues. In contrast, the LARS ligament, during repeated long-term exercise, can cause the bone canal to gradually enlarge and the ligament to fall off due to abrasion with the surrounding bone tissue. Statistics show that over 30% of patients need to undergo revision surgery after surgery, and about 78% of implanted ligaments cannot continue to perform ligament functions 15 years after reconstructive surgery. How to further effectively promote the integration of the ligament with surrounding tissues while realizing the mechanical function of the ligament and realize the implantation of the ligament-bone interface similar to the natural ligament-bone interface is a research subject which needs to be solved and is difficult and serious.

Disclosure of Invention

The invention aims to meet the mechanical requirements of the current medical implanted ligament, solve the problems of bone tissue abrasion, difficult self-tissue regeneration, poor biological integration and the like of the current implanted ligament and provide an implantable ligament substitute material based on oriented carbon nanotube fiber and a preparation method thereof.

The invention obtains highly oriented carbon nanotube material by vapor deposition method, and obtains first-stage spiral carbon nanotube fiber by dry spinning; then, a second-level spiral fiber is constructed by twisting one or more strands of first-level fibers; and finally, twisting one or more strands of secondary fibers to construct a structure, and releasing stress to obtain the three-stage double-spiral structure fiber. The fiber has excellent mechanical property and strong fatigue resistance, can meet the mechanical requirement of artificial ligaments, and has nanoscale oriented pore channels and micron-sized pore channels similar to natural ligaments, so that autologous tissue regeneration and osseous tissue integration can be effectively promoted.

The invention provides a preparation method of an implantable ligament substitute material based on oriented carbon nanotube fibers, which comprises the following specific steps:

(1) preparing primary spiral oriented carbon nanotube fibers; there are two different synthetic routes using vapor deposition and dry spinning methods:

firstly, synthesizing a carbon nano tube array by a chemical vapor deposition method, connecting pulled carbon nano tube belts by a spindle with a sharp head, and then rotating at a constant speed to spin a primary spiral orientation carbon nano tube fiber;

secondly, continuously preparing narrow carbon nanotube bands by a floating catalytic vapor deposition method, connecting the pulled narrow carbon nanotube bands by a spindle with a tip, and then rotating at a constant speed to spin a primary spiral oriented carbon nanotube fiber;

(2) preparing a secondary fiber with a spiral structure; arranging one or more strands of primary fibers in parallel, fixing one end of each strand of primary fibers, connecting the other end of each strand of primary fibers with an electric motor, and rotating the primary fibers at a constant speed through the electric motor to obtain multi-stage twisted secondary fibers with a spiral structure;

(3) preparing a three-stage carbon nanotube fiber with a double-spiral structure; and (2) fixing two ends of one or more strands of secondary fibers by maintaining stress at the two ends, arranging the two fibers in parallel, folding the fibers to overlap the two original fixed ends by taking the middle position as a symmetrical point, keeping the original fixed ends stable, and releasing the stress at the middle position to obtain the three-stage carbon nanotube fiber with the double-spiral structure.

The prepared tertiary carbon nanotube fiber can be used as a ligament implantation substitute material.

In the step (1), the controllable orientation spiral carbon nanotube fiber is obtained, the carbon nanotubes in the fiber are highly orderly arranged, and the fiber helix angle is 0-60 degrees, preferably 20-60 degrees; the fiber diameter is 10-150 mu m. The spiral angle and the fiber diameter can be regulated and controlled through the rotating speed of a motor, the width of a carbon nano tube belt and twisting time;

wherein the fiber type may be one of natural fiber, polymer fiber or carbon nanotube fiber.

In the step (2), the secondary fiber with the spiral structure is obtained, and the fiber has an ordered controllable spiral structure, wherein the number of the primary fibers is 1-100, and preferably the number of the primary fibers is 50-100; the diameter of the secondary fiber is 10-5000 mu m; the fiber helix angle is 0-60 degrees, preferably 20-60 degrees; the spiral angle and the fiber diameter can be regulated and controlled by the motor rotating speed, the primary fiber diameter, the primary fiber strand number and the twisting time.

In the step (3), a tertiary fiber with a double helix structure is obtained, wherein the number of secondary fibers is 1-100, and preferably the number of secondary fibers is 50-100; the diameter of the spiral structure is 20-10000μm, and the pitch is larger than 10μm (generally 10μm-30μm); the diameter and the pitch of the spiral structure can be regulated and controlled by the electrode rotating speed, the diameter of the secondary fiber, the number of strands of the secondary fiber and the twisting time.

The fiber prepared by the method has excellent mechanical property, the tensile modulus can reach 1.4-4GPa, the tensile elongation at break is 10-30%, the mechanical property can be effectively maintained after repeated bending for 1000000 times, and the mechanical requirement of ligaments can be effectively met. The density of the product is 0.3-0.9g/cm³And has a large number of nano-scale and micro-scale oriented pores similar to the autologous ligament structure. Therefore, the fiber can be used as ligament implantation material for animals such as mice, rabbits, cats, dogs, sheep, pigs, human beings, etc.

The positive progress effects of the invention are as follows:

(1) ordered nano-scale and micron-scale pore canals similar to autologous ligaments are introduced into the fibers in the preparation and assembly processes, so that autologous tissue regeneration and osseous tissue integration are effectively promoted;

(2) the fiber can realize simple and efficient adjustment of fiber diameter, spiral angle and thread pitch by controlling the number of primary fiber strands and secondary fiber strands and twisting conditions, so as to meet the requirements of different animals and different application scenes;

(3) the fiber can avoid introducing other bioactive substances such as growth factors, cells and the like in the preparation process, and a structural strategy is selected to realize biological integration, so that the preparation process is simple, the clinical application is easy, and the structural design of other implant materials can be expanded.

Drawings

FIG. 1 is a photograph and a scanning electron microscope of a first-order spirally-oriented carbon nanotube. Wherein, a is a photo of the oriented carbon nanotube ribbon pulled out from the spinnable carbon nanotube array, b is a photo of the preparation process of the primary spiral oriented carbon nanotube fiber, c is a scanning electron microscope picture, and d is a high-orientation arrangement display of the carbon nanotubes under high multiple.

FIG. 2 is a mechanical property test chart of the primary helical oriented carbon nanotube fiber. Wherein a is the tensile break curve of a primary fiber; b is the change in mechanical properties over 1000000 bending cycles.

Fig. 3 is a scanning electron microscope image of a three-stage carbon nanotube fiber, wherein a is the scanning electron microscope image, and b is the high-magnification micron-sized pore channel display.

Fig. 4a is a schematic view of the implantation and fixation of a multistage fiber through an anterior cruciate ligament reconstruction procedure. Fig. 4b is a model of a new zealand rabbit implanted with multilevel carbon nanotube fibers as a replacement ligament.

FIG. 5 is a Micro-CT three-dimensional reconstruction graph showing that the diameter of the bone canal gradually decreases with time after the multilevel carbon nanotube fiber is implanted as a substitute ligament into a New Zealand rabbit for 0 week, 4 weeks and 13 weeks.

FIG. 6 shows that the jumping function of the New Zealand rabbit is recovered 13 weeks after the multilevel carbon nanotube fiber is implanted into the New Zealand rabbit as a substitute ligament.

Detailed Description

Example 1 preparation of first-order spirally-oriented carbon nanotube fiber

(1) Chemical vapor deposition method for preparing first-order spiral oriented carbon nano tube fiber

Using a silicon wafer as a substrate, and depositing Al with the thickness of 10nm on the silicon wafer by an electron beam evaporation coating instrument in sequence₂O₃And Fe as a catalyst with a thickness of 1 nm. The catalyst was placed in a tube furnace with ethylene, argon and hydrogen as the carbon source, carrier gas and reducing gas, respectively, at flow rates of 90sccm, 400 sccm and 30sccm, respectively, at 740^oAnd C, reacting for 10 minutes to obtain the highly oriented carbon nanotube array on the substrate. The carbon nanotube ribbon is pulled out from the array by a blade, collected and fixed at the tail end of a spindle, and rotated at a constant speed to continuously obtain the oriented spiral carbon nanotube fiber (shown in figures 1a and b). Controlling the rotating speed of the motor to be 1000 revolutions per minute and the pulling speed to be 1cm/s, and obtaining the motor with the diameter of 10 mu mFirst-order helical oriented carbon nanotube fibers;

(2) preparation of first-order spiral oriented carbon nano tube fiber by floating catalytic vapor deposition method

In a floating catalytic reactor, 1 to 3 mass percent of thiophene and ferrocene are used as catalysts in percentage by mass>97% ethanol as carbon source, argon gas at a flow rate of 200sccm as carrier gas, and hydrogen gas at a flow rate of 1000sccm as reducing gas were continuously injected into the quartz tube at 1200 sccm^oC is reaction temperature, carbon nano tube aerogel can be continuously obtained, the oriented carbon nano tube belt can be obtained by sequentially shrinking water and ethanol, and the oriented carbon nano tube belt can be continuously collected on a PET tube. Fixing the carbon nanotube belt at the tail end of the spindle, and rotating at a constant speed to obtain the oriented spiral carbon nanotube fiber. The width of the carbon nano tube strip is controlled to be 1mm, the rotating speed of the electrode is 1000 r/min, and the primary spiral oriented carbon nano tube fiber with the diameter of 20 mu m can be obtained.

The carbon nanotube fibers in the primary helical oriented carbon nanotube fibers are highly oriented and arranged, and a large number of nanoscale oriented pore channels are introduced on the surfaces of the fibers (figures 1c and d). The mechanical property, modulus of rupture is 1.4N/tex, elongation at break is 19.9%, and the mechanical property is maintained after repeated stretching for 1000000 times (figure 2).

Example 2 preparation of two-stage spirally oriented carbon nanotube fiber

50 primary spiral carbon nanotube fibers with the lengths of 20cm and the diameters of 10μm are arranged in parallel, put together to one position, the two ends of the primary spiral carbon nanotube fibers are fixed, one end of the primary spiral carbon nanotube fibers is fixed on an electric rotating machine, the other end of the primary spiral carbon nanotube fibers is fixed, the primary spiral carbon nanotube fibers rotate at a constant speed for 30s at the rotating speed of 1000 revolutions per minute, and secondary fibers with the lengths of about 10 cm and the diameters of about 150μm are obtained.

Example 3 preparation of three-stage double helix carbon nanotube fiber

5 length are 20cm, and diameter is 150 mu m's second grade fibre parallel arrangement, puts together to a department, and both ends are fixed, gets one of them end and is fixed in the commentaries on classics machine, and the other end maintains to be fixed and does not understand, and at the uniform velocity rotatory 30 seconds of 1000 revolutions per minute, take off both ends simultaneously and keep length unchangeable, be fixed in on the paper, clip the fibre intermediate position with tweezers, fold the fibre, make two stiff ends coincide, fix together, loosen tweezers, make stress release, can obtain tertiary double helix structure fibre.

The tertiary fiber with double helix structure is shown in the electron micrograph of FIG. 3. The nanometer pore structure of the primary fiber is preserved in the tertiary fiber, and a large amount of micron pore structures among the primary fibers and among the document fibers are introduced.

Example 4, a three-stage duplex carbon nanotube fiber was implanted as a ligament replacement material on a new zealand rabbit model.

The carbon nanotube fiber shows good biocompatibility in a living body, can be highly integrated with compact bone tissues, skeletal muscles, bone mucosa tissues and the like after being implanted into tissues for three months, and does not show the accumulation of the carbon nanotubes in other metabolism-related kidneys. Therefore, the multistage double-helix carbon nanotube fiber is used as a ligament substitute material, and a new Zealand rabbit model with the weight of 3kg is implanted through an anterior cruciate ligament reconstruction operation. The specific operation is that a drilling machine is used for manufacturing a cylindrical defect with the diameter of 2mm on the femur and the tibia of the hind leg of a rabbit, a tertiary fiber with the diameter of 1.5mm is implanted into the defect part through the standard operation flow of the anterior cruciate ligament reconstruction operation, and the tail end is knotted for fixing, as shown in figure 4.

After the implantation, the change of the bone channel is observed in real time through Micro-CT, and the bone channel width is 1.51mm at 4 weeks and 1.21mm at 13 weeks, at which time the bone channel width is smaller than the diameter of the implanted multi-stage carbon nanotube fiber (figure 5), so that the bone tissue can be presumed to grow into the Micro-pores of the carbon nanotube. And (3) respectively taking the femur and the tibia for tissue section staining at 4 weeks and 13 weeks, finding new bones between the defective bones and the implanted fibers at 4 weeks, and growing the new bones into multi-stage fiber micron pore canals at 13 weeks to be consistent with the diameter change of the micron-CT bone canals. The jumping function was also restored in new zealand rabbits implanted with carbon nanotube ligament replacement material (fig. 6).

Claims

1. A preparation method of an implantable ligament substitute material based on oriented carbon nanotube fibers is characterized by comprising the following specific steps:

(3) preparing a three-stage carbon nanotube fiber with a double-spiral structure; one strand or a plurality of strands of secondary fibers are fixed by keeping the stress at two ends, are arranged in parallel, take the middle position as a symmetrical point, are folded until the two original fixed ends are overlapped, keep the original fixed ends stable, and release the stress at the middle position to obtain the three-stage carbon nanotube fiber with a double-spiral structure; the tertiary carbon nanotube fiber is the implantable ligament substitute material.

2. The method according to claim 1, wherein the fiber type in step (1) is one of natural fiber, polymer fiber or carbon nanotube fiber.

3. The preparation method according to claim 1, wherein the controllable orientation helical carbon nanotube fiber obtained in step (1) has a fiber helix angle of 20 to 60 degrees; the fiber diameter is 10-150 mu m; the spiral angle and the fiber diameter are regulated and controlled by the rotating speed of the motor, the width of the carbon nano tube belt and the twisting time.

4. The production method according to claim 1, wherein the secondary fiber having a helical structure obtained in the step (2), wherein the number of the primary fibers is 1 to 100; the diameter of the secondary fiber is 10-5000 mu m, and the helix angle of the fiber is 20-60 degrees; the spiral angle and the fiber diameter are regulated and controlled by the motor rotating speed, the primary fiber diameter, the primary fiber strand number and the twisting time.

5. The production method according to claim 1, wherein the tertiary fiber having a double helix structure obtained in the step (3), wherein the number of the secondary fibers is 1 to 100; the diameter of the spiral structure is 20-10000 mu m, and the pitch is larger than 10 mu m; the diameter and the pitch of the spiral structure are regulated and controlled by the electrode rotating speed, the diameter of the secondary fiber, the number of strands of the secondary fiber and the twisting time.

6. An implantable ligament substitute material based on oriented carbon nanotube fibers, obtained by the preparation method of any one of claims 1 to 5, having a tensile modulus of 1.4-4GPa and a tensile elongation at break of 10-30%, wherein the mechanical properties are effectively maintained after repeated bending of 1000000 times; the density of the product is 0.3-0.9g/cm³And has a large number of nano-scale and micro-scale oriented pores similar to the autologous ligament structure.

7. Use of an implantable ligament replacement material based on oriented carbon nanotube fibers of claim 6 as a ligament implant material in an animal.

8. The use of claim 7, wherein the animal is a mouse, rabbit, cat, dog, sheep, pig or human.