CN109260524B

CN109260524B - Nano short fiber material for tissue repair and preparation method and application thereof

Info

Publication number: CN109260524B
Application number: CN201811095518.2A
Authority: CN
Inventors: 张海涛; 邓坤学; 袁玉宇
Original assignee: Medprin Regenerative Medical Technologies Co Ltd
Current assignee: Medprin Regenerative Medical Technologies Co Ltd
Priority date: 2018-09-19
Filing date: 2018-09-19
Publication date: 2021-07-16
Anticipated expiration: 2038-09-19
Also published as: CN109260524A

Abstract

The invention relates to a nano short fiber material for tissue repair and a preparation method and application thereof. The nano short fiber material comprises nano short fibers, the diameter of each nano short fiber is 200-800 nm, the length of each nano short fiber is 10-200 mu m, and the surface of at least one nano short fiber has a porous structure. The nano short fiber material provided by the invention shortens the length of nano fibers, has better dispersion performance, is prepared from degradable biological materials with good biocompatibility and tissue repair performance, does not need to be removed, does not need secondary operation, and is particularly suitable for tissue repair of small-area or deep defects. In addition, the nano short fiber material provided by the invention can be prepared into powder, injection and the like, can be independently applied in combination with minimally invasive, laparoscopic, injection and other operation modes, and can also be compounded with other materials for use.

Description

Nano short fiber material for tissue repair and preparation method and application thereof

Technical Field

The invention belongs to the field of tissue repair materials, and particularly relates to a nano short fiber material for tissue repair, and a preparation method and application thereof.

Background

Minimally invasive surgery is a new trend in surgical clinics. Compared with the traditional operation, the incision caused by the minimally invasive operation is small, the recovery of the patient is fast, and the incidence rate of complications such as infection and the like is also obviously reduced. With the popularization of minimally invasive surgery, the matching of corresponding minimally invasive medical instruments is also required. The tissue repair product is used as a high-end consumable in medical instruments, can provide necessary supporting and filling effects for the defect part, and meanwhile, the microstructure of the tissue repair product is favorable for adhesion, migration and proliferation of tissue cells, so that the repair of the defect part is greatly accelerated.

Among tissue repair products, the tissue engineering scaffold prepared by the electrostatic spinning technology is a more innovative tissue repair product at present. The electrostatic spinning (electrospinning) technology is an effective method for preparing nano-to micron-sized fibers, the equipment is simple and easy, the cost is low, and the prepared tissue engineering scaffold has the advantages of high specific surface area, controllable diameter and porosity of the nano-fibers, particularly capability of obtaining a three-dimensional network structure similar to a natural extracellular matrix and the like, and is widely used for preparing the tissue engineering scaffold.

The repairing mechanism of the electrospinning tissue repairing product is mainly that micro-nano fibers are used for forming a three-dimensional network structure to simulate natural extracellular matrix, so that the adhesion, migration and proliferation of cells are promoted. However, the currently prepared electrospun tissue repair products are mostly in the shape of sheets or blocks formed by continuous long fibers and cannot meet the requirements of minimally invasive surgery.

Therefore, the development of a nano short fiber material which can meet the requirements of minimally invasive surgery is of great significance.

Disclosure of Invention

The invention aims to overcome the defect that the conventional electrospun tissue repair product is mostly in a sheet or block shape consisting of continuous long fibers and cannot meet the requirement of minimally invasive surgery, and provides a nano short fiber material for tissue repair. The nano short fiber material provided by the invention shortens the length of the nano fiber, improves the dispersibility of the nano fiber and widens the application range of the nano short fiber material; can be prepared into blocks, powder or injection, is delivered to the defect part by an injector, an endoscope or an interventional catheter, meets the requirement of minimally invasive surgery, and keeps the tissue repair function of the nano-fiber.

Another object of the present invention is to provide a method for preparing the above-mentioned nano short fiber material for tissue repair.

It is another object of the present invention to provide an injectable tissue repair nano-staple fiber material.

The invention also aims to provide the application of the nano short fiber material for tissue repair in minimally invasive surgery.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

the nanometer short fiber material for tissue repair comprises nanometer short fibers, the diameter of the nanometer short fibers is 200-800 nm, the length of the nanometer short fibers is 10-200 mu m, and the surface of at least one nanometer short fiber has a porous structure.

Compared with the existing nanofiber material, the nanofiber material provided by the invention has the advantages that the length of the nanofiber is shortened, and the length is distributed between 10-200 mu m. The inventor of the invention proves that the nano short fiber is distributed in the interval, so that the nano short fiber material provided by the invention has better dispersion performance, and can promote infiltration of inflammatory cells such as macrophages and the like to an affected part, meanwhile, the nano short fiber is not phagocytized by the macrophages, so that the inflammatory cells are promoted to continuously improve the microenvironment of cells of the affected part, and a microenvironment foundation is provided for entry of histiocytes such as fibroblasts and the like.

The porous structure on the surface of the short fiber further increases the specific surface area of the short fiber. The porous structures play a role of 'hand grasping' when the short fibers are mixed with other products (such as physiological saline, biological ink or biological glue and the like), increase the dissociating difficulty of the short fibers, improve the dispersibility of the short fibers and be beneficial to the mixed products to exert the multiple functions. Meanwhile, the porous structure also enables the adhesion protein of the cells to be preferentially and greatly enriched at the porous structure when the short fibers and the cells are interacted, so that the adhesion of the cells on the short fibers is more abundant.

Preferably, the relative standard deviation of the distribution of the lengths of the nanofibrous fibers is not more than 40%.

Preferably, the length of the nano short fiber is 30-50 μm.

Preferably, the nano short fiber is obtained by hydrolyzing a fiber raw material, wherein the fiber raw material comprises a polylactic acid material, and the mass fraction of polylactic acid in the polylactic acid material is not less than 50%.

The polylactic acid material can undergo autocatalytic hydrolysis reaction, meanwhile, the polylactic acid is a semi-crystalline polymer, and the hydrolysis of the polylactic acid fiber occurs from an amorphous area to a crystalline area. Therefore, the amorphous area in the fiber is preferentially hydrolyzed, the nano fiber is basically cut off after the amorphous area is hydrolyzed, so that the nano short fiber can be obtained, the surface of the hydrolyzed nano short fiber can generate porous structures with different sizes, and the porous structures are formed by hydrolyzing the easily hydrolyzed part in the section (crystallization area) which is not easy to hydrolyze on the nano fiber in advance.

In order to ensure that the polylactic acid forms a continuous phase at the chain breaking site in the composite phase, the content of the polylactic acid is at least more than 50 percent. When the content is less than 50%, the polylactic acid can not form a continuous phase in the composite fiber, and during ammonolysis, the nano fiber can not be broken to form short fiber even if the polylactic acid is completely degraded.

Preferably, the polylactic acid material comprises one or more of polylactic acid, polylactic acid-polyglycolic acid copolymer, polylactic acid-polyethylene glycol copolymer or poly epsilon-caprolactone-polylactic acid copolymer.

The polylactic acid materials have good biocompatibility and tissue repair capability, simultaneously have good spinnability, and can be conveniently prepared into nano fibers by an electrostatic spinning technology; meanwhile, the material contains lactic acid groups and can be used as chain breaking sites for hydrolysis treatment.

Preferably, the fiber raw material further comprises a functional filler; the mass fraction of the functional filler in the fiber raw material is not more than 25%.

Preferably, the functional filler is one or more of polydioxanone, polyanhydride, gelatin, collagen, hyaluronic acid, chitosan, fibroin, fibrin, pectin, starch and derivatives thereof, cellulose and etherate thereof, polyoxyethylene, polyvinyl alcohol or polyethylene glycol.

The addition of the functional filler does not affect the crystallization performance and the hydrolysis performance of the main material, and the functional filler embedded into the unhydrolyzed part of the main material has a promoting effect on the tissue repair performance of the nano short fiber.

The preparation method of the nano short fiber material for tissue repair comprises the following steps:

s1: preparing a polylactic acid material into nano fibers by using an electrostatic spinning technology;

s2: and (5) putting the nano-fibers obtained in the step (S1) into an ammonia water solution for hydrolysis, cleaning, filtering, and freeze-drying to obtain the nano-short fibers.

Besides the axial length of the nano short fiber subjected to the ammonia hydrolysis treatment is obviously shortened, some porous structures are found on the surface of the nano fiber. These porous structures are produced by hydrolysis of PLA molecules distributed on the surface of the fibres during the hydrolysis process.

The preparation method provided by the invention can successfully prepare the nano short fiber with better dispersion performance, and the method utilizes the autocatalytic hydrolysis reaction to carry out rapid preparation, thereby maintaining the biocompatibility and tissue repair performance of the nano short fiber material.

Preferably, the mass fraction of the ammonia water solution is 5% -25%.

The inventor finds that the hydrolysis promoting effect of the ammonia water is the best in the test process, and the ammonia water has a relatively proper reaction rate when the concentration is 5% -25%, so that the normal preparation requirement can be met.

Preferably, the mass-to-liquid ratio (g/ml) of the nanofibers to the ammonia solution in S2 is 1: 5-1: 50.

More preferably, the mass-to-liquid ratio (g/ml) of the nanofibers to the ammonia solution in S2 is 1:5 to 1: 10.

The mass-to-liquid ratio (g/ml) referred to herein refers to the ratio of the mass of the nanofibers to the volume of the ammonia water.

Preferably, the hydrolysis reaction is terminated after the hydrolysis treatment in S2 by: adjusting the pH of the hydrolysis treatment =7, or adjusting the mass fraction of ammonia to less than 5%.

Preferably, the cleaning in S2 further comprises a step of deamination, wherein deamination is performed by rotary distillation.

More preferably, the temperature of the rotary distillation is 45 ℃ and the pressure is 0.5 atm.

The deamination treatment is used for removing unreacted ammonia gas, and the ammonia gas which is evaporated by rotary evaporation can be dissolved in water again to form ammonia water for the next preparation process.

Preferably, the cleaning liquid for cleaning in S3 is pure water.

Preferably, the filtering process is suction filtration, and the aperture of the filter paper during suction filtration is 10-30 μm.

The washing and filtering functions to remove hydrolysis products produced by the hydrolysis reaction and remove short nanofibers having a small length. The short nano-fiber with small length is easy to be phagocytized by macrophages, and has little effect on stimulating the body to repair.

The application of the nano short fiber material for tissue repair in minimally invasive surgery is also within the protection scope of the invention.

Preferably, the tissue repair nano-staple fiber material is supplied in the form of powder, bulk or injection and delivered using a catheter, endoscopic channel or injection.

Preferably, when the tissue repair nano-short fiber material is supplied in the form of an injection solution, the injection solution includes the tissue repair nano-short fiber material and a dispersion solution.

Compared with the prior art, the invention has the following beneficial effects:

the nano short fiber material provided by the invention shortens the length of nano fibers, has better dispersion performance, is prepared from degradable biological materials with good biocompatibility and tissue repair performance, does not need to be removed, does not need secondary operation, and is particularly suitable for tissue repair of small-area or deep defects. In addition, the nano short fiber material provided by the invention can be prepared into powder, injection and the like, can be independently applied in combination with minimally invasive, laparoscopic, injection and other operation modes, and can also be compounded with other materials for use. The preparation method of the nano short fiber material provided by the invention solves the technical problem that the agglomeration of the nano fiber film or the nano fiber is serious in the crushing process. The method utilizes autocatalytic hydrolysis reaction for rapid preparation, and maintains biocompatibility and tissue repair performance of the nano short fiber material.

Drawings

FIG. 1 is a topographical view of a tissue repair nano-staple fiber material provided in example 1;

FIG. 2 is a schematic view of a hydrolysis reaction for preparing a nano short fiber material for tissue repair in example 1;

FIG. 3 shows the length and distribution of the short nanofibers of the tissue repair nanofiber material provided in example 1;

fig. 4 is a formulation of nano-staple fibers: (a) powder preparation; (b) an injection solution;

fig. 5 is a graph showing the results of animal experiments on the tissue repair nanofiber material provided in example 1: (a) experimental group anatomical mapping; (b) a control anatomical map; (c) pathological result graphs of experimental groups; (d) pathological result chart of control group.

Detailed Description

The present invention will be further described with reference to the following examples. These examples are merely representative descriptions of the present invention, but the present invention is not limited thereto. The test methods used in the following examples are, unless otherwise specified, all conventional methods, and the raw materials, reagents and the like used are, unless otherwise specified, all commercially available raw materials and reagents.

In the invention, the length of the nano short fiber material is measured by the following specific steps:

1. dispersing the nano short fiber material in a proper amount of water, dropwise adding the nano short fiber material on a glass slide, covering a cover glass, and removing water in a 37 ℃ oven;

2. observing the nano short fiber by using an optical microscope, wherein the magnification is 400X, and randomly taking 3 visual fields for photographing;

3. measuring the length of the nano short fiber in the photos by using Image Pro software, and randomly measuring 50 points in each photo;

4. 3 different batches of the nano short fiber material made of the same material are selected, 3 samples are randomly taken from each batch, 3 visual fields are randomly taken from each sample for photographing, and 50 points are randomly taken from each visual field for measurement, so that the nano short fiber material made of each material can obtain 1350 data, and has statistical significance; and the 1350 data are analyzed statistically to obtain the length and distribution of the nano short fiber.

For the set of discrete data of the length of the nano-short fiber, the standard deviation can be used to characterize the discrete degree of the length distribution. However, the arithmetic mean values of different groups are different, and the standard deviation cannot be compared transversely, so that the invention supplements the discrete degree of the length distribution of the characterization nano-short fiber by using Relative Standard Deviation (RSD). The relative standard deviation means: the ratio of the standard deviation to the arithmetic mean of the calculated results.

Relative standard deviation calculation formula:

relative Standard Deviation (RSD) = Standard Deviation (SD)/arithmetic mean (X) of calculation result by 100%.

Example 1 preparation of polylactic acid nano staple fiber material

This example provides a polylactic acid staple nanofiber material, which is prepared as follows.

S1, adding 0.8g of polylactic acid into 10ml of hexafluoroisopropanol solution, and stirring at normal temperature until the polylactic acid is dissolved to prepare 8% (w/v) spinning solution;

s2, adding the spinning solution into an injector, adding an extension tube at the front end of the injector and connecting with a 20G needle, placing the injector on a micro-injection pump, wherein the needle is vertical to a receiving flat plate, and the lower part of the receiving plate is grounded; setting the injection rate to be 6ml/h, and loading a voltage of 22kv on the needle point when the needle point is extruded with the solution; at the moment, the nano-fibers are sprayed out and collected on a receiving plate to form a nano-fiber film;

s3, drying the nanofiber membrane in vacuum for 48 hours to remove hexafluoroisopropanol, transferring the nanofiber membrane into 15% ammonia water according to the mass-to-liquid ratio of 1:5, standing for 10 minutes to be pasty, loading the nanofiber membrane into a stirrer with a speed of 300rpm, and then processing the nanofiber membrane for 10 minutes to obtain uniform suspension;

s4 neutralizing the suspension by adding a quantity of hydrochloric acid until pH = 7; transferring to a rotary steaming bottle, and performing deamination treatment by using a rotary steaming instrument, wherein the rotary steaming temperature is 45 ℃, and the air pressure is 0.5 atm;

s5, adding a large amount of pure water into the deaminated suspension, filtering the deaminated suspension through 10-30 mu m filter paper, collecting a filter cake, adding water again, performing suction filtration, and repeating the steps for 3 times;

and S6, adding a small amount of pure water into the filter cake after cleaning and filtering to prepare suspension, freezing and curing in a low-temperature refrigerator at (-80 ℃), and then freezing and drying to obtain the polylactic acid nano short fiber.

The obtained polylactic acid nano short fiber material is powder, and the microstructure is shown in figure 1. The diameter of the nano short fiber is 300-600 nm, the length is not more than 160 mu m, the surface of the nano short fiber has a porous structure, the relative standard deviation of length distribution data is 28.45%, and the length and the distribution diagram are shown in figure 3. The hydrolysis process is shown in fig. 2, wherein the dark color part is a section (generally a crystalline region) which is not easy to hydrolyze in the nanofiber, the light color part is a section (generally an amorphous region) which is easy to hydrolyze, and the short fiber can be obtained by starting hydrolysis from the amorphous region and controlling the hydrolysis time and conditions; the porous structure is formed by pre-hydrolysis of the easily hydrolyzed part in the non-easily hydrolyzed section (crystallization area).

EXAMPLE 2 preparation of PLGA/gelatin Nanofibre Material

This example provides a PLGA/gelatin staple nanofiber material prepared as follows.

S1, adding 1g of PLGA into 10ml of hexafluoroisopropanol solution, stirring at normal temperature until the solution is dissolved, adding 0.2g of gelatin, and preparing 10% (w/v) spinning solution after the gelatin is dissolved;

s2, adding the spinning solution into an injector, adding an extension tube at the front end of the injector and connecting with a 23G needle, placing the injector on a micro-injection pump, wherein the needle is vertical to a receiving flat plate, and the lower part of the receiving flat plate is grounded; setting the injection rate to be 2ml/h, and loading a voltage of 30kv on the needle point when the needle point is extruded with the solution; at the moment, the nano-fibers are sprayed out and collected on a receiving plate to form a nano-fiber film;

s3, drying the nanofiber membrane in vacuum for 48h to remove hexafluoroisopropanol, transferring the nanofiber membrane into 10% ammonia water according to the mass-to-liquid ratio of 1:10, standing for 10min to be pasty, loading the nanofiber membrane into a stirrer with a speed of 300rpm, and then processing the nanofiber membrane for 10min to obtain uniform suspension;

s4, adding a large amount of pure water into the suspension to dilute ammonia water; transferring to a rotary steaming bottle, and performing deamination treatment by using a rotary steaming instrument, wherein the rotary steaming temperature is 45 ℃, and the air pressure is 0.5 atm;

The obtained polylactic acid nano short fiber material is powder, and the microstructure is shown in figure 2. The diameter of the nano short fiber is 200-800 nm, the length is not more than 200 mu m, and the relative standard deviation of the length distribution data is 35.11%.

Example 3

s3, drying the nanofiber membrane in vacuum for 48h to remove hexafluoroisopropanol, transferring the nanofiber membrane into 25% ammonia water according to the mass-to-liquid ratio of 1:50, standing for 10min to be pasty, loading the nanofiber membrane into a stirrer with a speed of 300rpm, and then processing the nanofiber membrane for 10min to obtain uniform suspension;

and S6, adding a small amount of pure water into the filter cake after cleaning and filtering to prepare suspension, freezing and curing in a low-temperature refrigerator at (-80 ℃), and then freezing and drying to obtain the polylactic acid nano short fiber. The diameter of the nano short fiber is 300-600 nm, the length is not more than 100 mu m, and the relative standard deviation of length distribution data is 12.39%.

Example 4

The embodiment provides a polylactic acid-polycaprolactone copolymer nano short fiber material, which is prepared by the following method.

S1, adding 1g of polylactic acid-polycaprolactone copolymer into 10ml of trifluoroacetic acid solution, and stirring at normal temperature until the polylactic acid-polycaprolactone copolymer is dissolved to prepare 10% (w/v) spinning solution;

s2, adding the spinning solution into an injector, adding an extension tube at the front end of the injector and connecting with a 23G needle, placing the injector on a micro-injection pump, wherein the needle is vertical to a receiving flat plate, and the lower part of the receiving flat plate is grounded; setting the injection rate to be 2ml/h, and loading 18kv of voltage on the needle tip when the needle tip is extruded with the solution; at the moment, the nano-fibers are sprayed out and collected on a receiving plate to form a nano-fiber film;

s3, drying the nanofiber membrane in vacuum for 48h to remove trifluoroacetic acid, transferring the nanofiber membrane into 20% ammonia water according to the mass-to-liquid ratio of 1:40, standing for 15min to be pasty, loading the nanofiber membrane into the ammonia water, stirring the nanofiber membrane gently at 100rpm, and treating the nanofiber membrane for 10min to obtain uniform suspension;

and S6, adding a small amount of pure water into the filter cake after cleaning and filtering to prepare suspension, freezing and curing in a low-temperature refrigerator (minus 80 ℃), and then freezing and drying to obtain the polylactic acid-polycaprolactone copolymer nano short fiber. The diameter of the nano short fiber is 100-500 nm, the length is not more than 150 mu m, and the relative standard deviation of length distribution data is 18.94%.

Example 5 mode of application of the NanoFibre Material obtained in examples 1 and 2

To illustrate the application of the nano-staple fibers made in the present invention, the following are specifically exemplified:

a1: the polylactic acid nano short fiber powder prepared in example 1 is taken, as shown in fig. 4 (a); directly filling the wound with the dressing, smearing the dressing on the tissue defect until the tissue defect is filled with the dressing, and suturing the wound or directly covering the wound with gauze.

A2: taking 0.5g of the PLGA/gelatin nano short fiber material prepared in the example 2, adding 10ml of 1% (w/v) hyaluronic acid aqueous solution to prepare a nano short fiber-hyaluronic acid injection, as shown in fig. 4 (b); the injection is slowly injected to the tissue defect, and the peripheral tissues of the defect are kneaded while injecting to uniformly distribute the injection until the defect is filled with the injection.

Example 6 animal experiments

In order to verify the actual tissue repair effect of the nano short fiber material, a muscle implantation mode is selected for animal experiments, and the method is characterized by referring to the 6 th part of the national standard GB/T16886.6-1997 medical instrument biological evaluation: local reaction test after implantation, using the nano-short fiber material prepared in example 1 as an experimental sample and a commercially available tissue repair membrane as a control sample, the specific process is as follows:

1. taking 6 healthy SD rats, anaesthetizing, preparing skin, and fixing in prone position;

2. disinfecting the buttocks of a rat by using iodophor alcohol, and respectively making a defect with the length of 3cm, the width of 1cm and the depth of 2cm on the gluteus muscles on two sides of the rat;

3. implanting a proper amount of nano short fiber material into one side defect, and implanting a control sample into the other side defect;

4. suturing muscles and skin;

5. normally feeding, and optionally administering a certain amount of antibiotics; after 2 weeks, the rat was sacrificed and observed by dissection, and the implanted site and its surrounding tissues of one of the rats were randomly selected and subjected to pathological analysis by HE staining.

The results of the dissection observation are shown in fig. 5 (a) and 5 (b), in which fig. 5 (a) is a dissected photograph of an experimental group (a nano-staple fiber material), and fig. 5 (b) is a dissected photograph of a control group (a commercially available tissue repair membrane). After dissection, the experimental group and the control group can see obvious cell infiltration, wherein the experimental group has obvious new capillary vessel structure, as shown in fig. 5 (a); both had some deformation in the muscle direction, and the control group had significantly greater deformation than the experimental group, as shown in fig. 5 (b).

The pathological test results are shown in fig. 5 (c) and 5 (d), in which fig. 5 (c) is the pathological test result of the experimental group (nano short fiber material), and fig. 5 (d) is the pathological test result of the control group (commercially available tissue repair membrane). The pathological results are similar, and both pathological results show that: 1. the implanted material is in a filament shape, the inside is loose, and a small amount of fibroblasts can be seen to grow into the material. The percentage of residual material area is about: 40-50% and no obvious gap is found between the particles and the surrounding tissues. 2. More fibrous tissue hyperplasia can be seen around the implant material, and a small amount of lymphocyte infiltration (less than or equal to 25 per HPF), a small amount of plasma cell infiltration (less than or equal to 25 per HPF), a small amount of macrophage infiltration (1-4 per HPF) and a large amount of multinuclear giant cell infiltration (> 5 per HPF) can be seen in the process. Of these, the experimental group was associated with massive capillary hyperplasia (8-20 per HPF), the control group with capillary hyperplasia (4-7 per HPF), and the control group with local adipocyte infiltration (< 20%).

From the above results, in the initial stage of implantation, the experimental group and the control group both exhibit good biological activity, show tissue irritation, promote inflammatory cell infiltration material, establish related cell environment, promote fibroblast to grow in, and cause fibrous tissue hyperplasia and capillary hyperplasia, and it can be seen that the tissue repair process has been started, and it can be predicted that the final material can complete the tissue repair process, and the experimental group results are slightly better than the control group. Meanwhile, the anatomical photographs show that the experimental group has better deformation resistance and support performance compared with the control group.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The nanometer short fiber material for tissue repair comprises nanometer short fibers, and is characterized in that the diameter of the nanometer short fibers is 200-800 nm, the length of the nanometer short fibers is 10-200 mu m, and the surface of at least one nanometer short fiber has a porous structure; the nano short fiber is obtained by hydrolyzing a fiber raw material with ammonia water, wherein the fiber raw material comprises a polylactic acid material, and the mass fraction of polylactic acid in the polylactic acid material is not less than 50%.

2. The tissue repair nano-staple fiber material of claim 1, wherein the relative standard deviation of the distribution of the nano-staple fiber lengths is no greater than 40%.

3. The tissue repair nanofiber material as claimed in claim 1, wherein the length of the nanofiber is 30 to 50 μm.

4. The tissue repair nanofiber material as claimed in claim 1, wherein the polylactic acid-based material includes one or more of polylactic acid, polylactic acid-polyglycolic acid copolymer, polylactic acid-polyethylene glycol copolymer, and poly-epsilon-caprolactone-polylactic acid copolymer.

5. The tissue repair nano-staple fiber material of claim 1, wherein the fiber raw material further comprises a functional filler; the mass fraction of the functional filler in the fiber raw material is not more than 25%.

6. The tissue repair nanofiber material as claimed in claim 5, wherein the functional filler is one or more of polydioxanone, polyanhydride, gelatin, collagen, hyaluronic acid, chitosan, fibroin, fibrin, pectin, starch and its derivatives, cellulose and its etherate, polyoxyethylene, polyvinyl alcohol, and polyethylene glycol.

7. A method for preparing the nano short fiber material for tissue repair according to any one of claims 1 to 6, characterized by comprising the following steps:

8. The method according to claim 7, wherein the aqueous ammonia solution is present in an amount of 5 to 25% by mass.

9. The preparation method of claim 7, wherein the mass-to-liquid ratio of the nanofibers to the ammonia solution in S2 is 1:5 to 1:50 g/ml.

10. The preparation method of claim 9, wherein the mass-to-liquid ratio of the nanofibers to the ammonia solution in S2 is 1:5 to 1:10 g/ml.

11. The method according to claim 7, wherein the hydrolysis reaction is terminated after the hydrolysis treatment in S2 by: adjusting the pH value of hydrolysis treatment to be 7, or adjusting the mass fraction of ammonia water to be less than 5%.

12. The method of claim 7, further comprising a step of deamination before washing in S2, wherein deamination is performed by rotary distillation.

13. The method of claim 12, wherein the rotary distillation temperature is 45 ℃ and the pressure is 0.5 atm.

14. The production method according to claim 7, wherein the cleaning liquid for cleaning in S2 is pure water; the filtering process is suction filtration, and the aperture of the filter paper during suction filtration is 10-30 mu m.

15. Use of the tissue repair nano-staple fiber material of any one of claims 1 to 6 in the preparation of minimally invasive surgical products.

16. The use according to claim 15, wherein the tissue repair nano-staple material is supplied in the form of a powder, a block or an injection solution and delivered by means of a catheter, endoscopic channel or injection.

17. The use according to claim 16, wherein when the tissue repair nano-staple fiber material is supplied in the form of an injection solution, the injection solution comprises the tissue repair nano-staple fiber material and a dispersion solution.