Preparation method of micro sleeve

Abstract

The invention relates to the technical field of biomedicine, in particular to a preparation method of a micro-cannula. The preparation method comprises the following steps: 1) melting a polymer, extruding the polymer from a hollow die head, and solidifying and forming the polymer in cold air or a water bath to form a continuous hollow fiber pipe, the outer diameter d1 of the hollow fiber pipe being 0.3-1.0 mm, and the inner diameter d2 of the hollow fiber pipe being 0.2-0.9 mm; (2) the hollow fiber pipe is fed into a clamp with threads, circumferential coating and radial extrusion are formed on the outer surface of the hollow fiber pipe, and the hollow fiber pipe with external thread lines is formed; (3) cutting the hollow fiber pipe with the external thread lines by using a cutter to obtain a micro sleeve; and 4) cleaning, drying, packaging and disinfecting the cut micro sleeve. By the adoption of the method, the casing pipe with the outer diameter not larger than 1 mm can be prepared.

Description

Technical Field

[0001] The present application relates to the field of biomedical technology, and in particular to a method for preparing a micro cannula. Background Art

[0002] With the development of modern medical technology, microsurgery has the advantages of precise surgical operation and minimal soft tissue trauma. It can successfully repair large defects that were previously unresolvable in one go. It is widely used in plastic surgery, neurosurgery, orthopedics, etc. Vascular anastomosis is the cornerstone of microsurgery, and the quality of vascular anastomosis is related to the success or failure of the entire operation.

[0003] For micro-vessels with a diameter of less than 2.0 mm, suturing is not suitable. Chemical bonding and stenting methods have safety risks due to the introduction of other substances. Laser and hot melting methods have the problem of insufficient initial strength. Mechanical anastomosis is a vascular anastomosis method that uses a special vascular anastomosis device to replace or partially replace sutures. According to its principle, it can be divided into staple method, sleeve method, magnetic tube method, needle ring method and anastomosis clip method. Among them, sleeve-type seamless suturing and ligation-type small vascular anastomosis have the advantages of simple sleeve structure, no need for adhesives, and good postoperative effect ([1] Robert D Foster, Tao Liu. Journal of Reconstructive Microsurgery, 2003, 19 (1), 49 (the material used is Teflon); [2] Robert SucH&Er, et al. al.Transplantation, 2010, 90(12), 1374 (the material used is polyamide), but there are certain requirements for the cannula: in addition to biological hygiene, the inner and outer diameters are required to be in the range of 0.1mm-1.0mm, and have certain support and surgical operability (soft materials cannot be used). Usually, stable polymer materials such as polytetrafluoroethylene, polyamide, polypropylene, polyester, and degradable polymer materials such as polylactic acid are selected.

[0004] To meet the above requirements, some information surrounding the design of the cannula structure has been disclosed. Patent (202021257595.6) and Patent (202122177402.7) disclose a structure of a vascular anastomosis cannula, including an outer tube and an inner core. The preparation method is not disclosed, and the inner core needs to be placed in the blood vessel, which poses a foreign body risk. Patent (202210502324.X) discloses a portal vein cannula structure with an outer diameter of 18-20G (1G = 0.254 mm). A groove is designed on the cannula, and it is fixed with silk thread during surgery, but no method for preparing the cannula is disclosed. Patent (201020292957.5) discloses a combined structure of an end tube and a cannula with barbs, but does not disclose the inner and outer diameters and the preparation method. Patent (202211599298.3) discloses a heat shrinkable sleeve and its preparation method, which replaces the silk thread ligation method during surgical operations. The patent does not disclose its use method in surgery. According to relevant papers (Luo Tingze et al., Journal of Medical Research, 2019, 48(2), 22), adhesives are required during surgery. Patent (200710035106.5) discloses a "degradable vascular anastomosis sleeve and its preparation method", which adopts the injection molding method and discloses the injection molding temperature conditions. Other conditions, especially the structure of the mold and the demoulding method, are not disclosed, making it difficult for professionals to reproduce this technology; the prepared sleeve has an outer diameter of 2.2mm, a wall thickness of 0.3mm, and a threaded outer wall, but other necessary structural dimensions are not disclosed. Patent (202011165848.1) discloses a polyimide sleeve structure suitable for vascular anastomosis with a diameter of less than 1.0mm, but does not disclose the preparation method.

[0005] In summary, the main problems with the cannulas currently used for sleeve-type seamless suture and ligation-type small vessel anastomosis are: first, the preparation technology of the cannulas is not public; second, the mold method makes it difficult to prepare cannulas with an outer diameter of less than 1 mm. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing a micro cannula with an outer diameter no greater than 1 mm suitable for sleeve-type sutureless and ligature-type small blood vessel anastomosis.

[0007] The technical solution of the present invention is:

[0008] A first aspect of the present invention provides a method for preparing a micro cannula, the method comprising the following steps:

[0009] 1) The polymer is melted and extruded from a hollow die, and solidified in cold air or a water bath to form a continuous hollow fiber tube, wherein the outer diameter d1 of the hollow fiber tube is 0.3 to 1.0 mm and the inner diameter d2 is 0.2 to 0.9 mm;

[0010] 2) feeding the hollow fiber tube into a fixture with threads, circumferentially coating and radially extruding the outer surface of the hollow fiber tube to form a hollow fiber tube with external thread patterns;

[0011] 3) Using a cutter to cut the hollow fiber tube with external thread lines to obtain a micro cannula;

[0012] 4) The cut micro cannula is cleaned, dried, packaged and sterilized.

[0013] A second aspect of the present invention provides a micro cannula, which is prepared using the method for preparing the micro cannula as described in the first aspect of the present invention.

[0014] A third aspect of the present invention provides a method for preparing a microcannula or application of the prepared microcannula in the biomedical field.

[0015] By adopting the above technical solution, the beneficial effects of the present invention are:

[0016] (1) The present invention selects polymer materials that meet the requirements of in vivo implantation and performs melt extrusion processing without involving solvents and other additives, which is beneficial for medical use scenarios;

[0017] (2) The melt extrusion equipment and process of the present invention are continuous and stable, and the outer and inner diameters of the obtained cannula are controllable and adjustable, with the outer diameter not exceeding 1 mm, making it suitable for repairing the femoral artery and femoral vein (or blood vessels with a diameter of 0.18 to 0.8 mm);

[0018] (3) The thread processing method of the outer surface of the present invention is uniform and controllable, suitable for batch production, and the pitch is slightly larger than the diameter of the tying wire (the pitch is 1.2-3.0 times the wire diameter), which is conducive to fixation;

[0019] (4) The present invention can be continuously engraved and cut, and is suitable for batch processing. The obtained hollow fiber tube has a pre-cut, and the user can easily peel it off manually to obtain the desired stepped tube;

[0020] (5) After packaging and disinfection, the present invention can be used directly in surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure shows the structure of the fixture used in the present invention, wherein: 1 - heating claw base, 2 - fixture base, 3 - heating claw, 4 - fixture guide rail, 5 - arc groove.

[0022] Figure 2 Shown is a partial enlarged view of the top of the heating jaws in the clamped state.

[0023] Figure 3Shown are the longitudinal section (left) and cross-section (right) structural views of the hollow fiber tube after being cut by the guillotine in the present invention.

[0024] Figure 4 Shown is a schematic diagram of the hollow fiber tube die of the present invention.

[0025] Figure 5 It is a schematic structural diagram of the double-layer hollow fiber tube of the present invention.

[0026] Figure 6 Schematic diagram showing the in vivo implantation steps of the microcannula according to Example 1 of the present invention.

[0027] Figure 7 Schematic diagram showing the in vivo implantation steps of the microcannula according to Example 2 of the present invention.

[0028] Figure 8 Shown are H&E staining comparisons of inflammatory cell infiltration in the pericannula tissue at 1 month and 6 months after surgery in Example 1 of the present invention and perivascular tissue in the positive control group.

[0029] Figure 9 The graph shows a comparison of the IL-2, IL-10, TNF-α and IFN-γ levels in the tissue surrounding the cannula at the 1st and 6th month after the operation in Example 1 of the present invention and those surrounding the blood vessels in the control group. There is no significant difference in the levels of inflammatory and rejection-related cytokines in the tissue surrounding the implanted PP cannula and those surrounding the blood vessels in the control group.

[0030] Figure 10 The figure shows a comparison of IL-2, IL-10, TNF-α and IFN-γ levels in the plasma of rats with cannula implantation at 1 month, 3 months and 6 months after surgery and those in the control group in Example 1 of the present invention. There was no significant difference in the levels of inflammatory and rejection-related cytokines in the plasma of rats in the experimental group and those in the control group.

[0031] Figure 11 The graph shows a comparison of liver and kidney function indicators in the plasma of rats implanted with cannulas at 1 month, 3 months and 6 months after surgery and those in the control group in Example 1 of the present invention. There is no significant difference in liver and kidney function indicators between the experimental group and the control group.

[0032] Figure 12 The graph shows the comparison of the average deposition density of IgG, IgM and C3c in the cannula perivascular tissue at 1 month and 6 months after surgery in Example 1 of the present invention and the perivascular tissue of the control group. There is no significant difference in the average deposition density of IgG, IgM and C3c in the implant perivascular tissue and the control group.

[0033] Figure 13The H&E staining of the liver and kidney tissues of rats implanted with cannula at 6 months after surgery in Example 1 of the present invention is compared with the liver and kidneys of rats in the control group. There is no significant difference in the H&E staining of the liver and kidney tissues of rats in the experimental group and the control group six months after surgery.

[0034] Figure 14 The figure shows the area comparison between the scratching with the extract in Example 1 of the present invention at 0 h and 24 h and the control group. The scratching with the extract shows that the PP sleeve has no effect on the cell migration ability.

[0035] Figure 15 The diagram shows the chromosome aberration observed and recorded under a microscope after the material extract in Example 1 of the present invention was applied to hamster lung cells. Figure 15 AD shows a normal chromosome under the microscope, with normal chromosome number, morphology and structure: Figure 15 A: -S9 solvent control group treatment; Figure 15 B: -S9 0.4g / ml PP extract treatment; Figure 15 C:-S9 0.2g / ml PP extract treatment; Figure 15 D: +S9 0.4g / ml PP extract treatment; Figure 15 EH is shown as abnormal chromosomes under the microscope: Figure 15 E:-S90.1g / ml extract treatment, Figure 15 The arrow E indicates the dicentric aberration of chromosomes after the extract of Example 1. Figure 15 F: -S9 treated with 0.1ug / ml mitomycin C, ring chromosomes appeared; Figure 15 G: +S9 20ug / m cyclophosphamide treatment, Figure 15 F, 15G arrow indicates the ring chromosome after the positive control group; Figure 15 H:-S9 treated with 0.1ug / ml mitomycin C, Figure 16 The arrowhead H indicates the chromosome defect after the positive control group was treated.

[0036] Figure 17 The figure shows the comparison of cell infiltration in the H&E staining of the tissue surrounding the cannula at 1 month and 3 months after surgery in Example 2 of the present invention and the perivascular tissue of the control group. The H&E staining of the tissue surrounding the PEI / PE cannula showed no significant difference in cell infiltration compared with the control group.

[0037] Figure 18 The graph shows a comparison of the IL-2, IL-10, TNF-α, and IFN-γ levels in the perivascular tissue of the cannula at 1 month and 3 months after surgery in Example 2 of the present invention and those in the perivascular tissue of the control group. There is no significant difference in the levels of inflammatory and rejection-related cytokines in the perivascular tissue of the implanted PEI / PE cannula and the perivascular tissue of the control group.

[0038] Figure 19 Figure 11 shows the comparison of IL-2, IL-10, TNF-a and IFN-g levels in the plasma of rats implanted with the cannula in Example 2 at 1 month and 3 months after surgery and the plasma of control rats. The levels of inflammatory and rejection-related cytokines in the plasma of the experimental rats were not significantly different from the control group.

[0039] Figure 20 Figure 12 shows the comparison of liver and kidney function indicators in the plasma of rats implanted with the cannula in Example 2 at 1 month and 3 months after surgery and the plasma of control rats. The liver and kidney function indicators of the experimental rats were not significantly different from the control group.

[0040] Figure 21 Figure 13 shows the comparison of the average deposition density of IgG, IgM and C3c in the tissue around the cannula in Example 2 at 1 month and 3 months after surgery and the tissue around the blood vessels of the control group. The average deposition density of IgG, IgM and C3c in the tissue around the implant was not significantly different from the tissue around the blood vessels of the control group.

[0041] Figure 22 Figure 14 shows the comparison of H&E staining of liver and kidney tissues of rats implanted with the cannula in Example 2 at 6 months after surgery and the histological staining of liver and kidney tissues of control rats. The H&E staining of liver and kidney tissues of the experimental rats at 3 months after surgery was not significantly different from the control group.

[0042] Figure 23 Figure 15 shows the comparison of the area of the scratch after 0h and 24h of the extract in Example 2 and the control group. The scratch of the extract showed that the PEI / PE cannula had no effect on cell migration.

[0043] Figure 23 Figure 16 shows the observation and recording of chromosomal aberration under a microscope after the extract of the material in Example 2 acted on hamster lung cells. Figure 23 A-D show normal chromosomal micrographs, with normal number, morphology and structure of chromosomes, Figure 23 A: -S9 solvent control group treatment; Figure 23 B: +S9 0.1g / ml extract treatment; Figure 23 C: +S9 0.2g / ml extract treatment; Figure 23 D: -S9 0.1g / ml extract treatment; Figure 23 E-H show abnormal chromosomal micrographs: Figure 23 E: -S9 0.1g / ml extract treatment, the arrow in Figure E, G shows the broken chromosomal monomer after the extract of Example 2 material acts; Figure 23 F: -S9 0.1ug / ml mitomycin C treatment, Figure 23 the arrow in Figure F shows the appearance of ring chromosomes after the positive control group acts;Figure 24 H: -S9

[0044] 0.1ug / ml mitomycin C treatment, Figure 25 The arrowhead H indicates the chromosome defect after the positive control group was treated.

[0045] Figure 26 Shown is a schematic structural diagram of the arc groove on the heating claw of the present invention.

[0046] Figure 1 Shown are schematic diagrams of the structure of the tool of the present invention; (a) a schematic diagram of the three-dimensional structure at a first angle; (b) a schematic diagram of the three-dimensional structure at a second angle.

[0047] Figure 24 Shown are finished products of the final micro cannula of the present invention, wherein: (a) is an axonometric view; (b) is a cross-sectional view; and (c) is an end view. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the method for preparing the microcannula provided by the present invention will be described in detail.

[0049] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to disclosing that the parameter is an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (1) and (2), which means that the method may include steps (1) and (2) performed sequentially, or may include steps (2) and (1) performed sequentially, or may include steps (2) and (3) performed synchronously. For example, the method may further include step (3), which means that step (3) may be added to the method in any order, for example, the method may include steps (1), (2) and (3), or may include steps (1), (3) and (2), or may include steps (3), (2) and (1), etc.

[0051] After extensive research, the inventors of this invention have developed a method for preparing a microcannula for sleeve-type sutureless and ligation-type small vascular anastomosis, achieving the production of a microcannula with an outer diameter of no more than 1 mm. The resulting microcannula has been used in sleeve-type sutureless and ligation-type small vascular anastomosis procedures and has met the requirements for in vivo and in vitro compatibility testing, including cytotoxicity, coagulation, hemolysis, scratch, bacterial reverse mutation, and in vitro mammalian cell chromosome aberration assays. Based on this, the present application has been completed.

[0052] Preparation method of micro cannula

[0053] The present invention provides a method for preparing a micro cannula, the method comprising the following steps:

[0054] 1) The polymer is melted and extruded from a hollow die, and solidified in cold air or a water bath to form a continuous hollow fiber tube, wherein the outer diameter d1 of the hollow fiber tube is 0.3 to 1.0 mm and the inner diameter d2 is 0.2 to 0.9 mm;

[0055] 2) feeding the hollow fiber tube into a fixture with threads, circumferentially coating and radially extruding the outer surface of the hollow fiber tube to form a hollow fiber tube with external thread patterns;

[0056] 3) Using a cutter to cut the hollow fiber tube with external thread patterns;

[0057] 4) The cut cannula is cleaned, dried, packaged and sterilized.

[0058] In the method for preparing the microcannula provided by the present invention, in step 1), the polymer is selected from a single-component polymer or a two-component polymer.

[0059] In step 1) of the present invention, the single-component polymer is selected from one of polypropylene, polyetheretherketone, polylactic acid, polyetherimide, polycaprolactone, polyglycolide, polylactic acid-glycolic acid copolymer, and polyethylene.

[0060] Among them, polypropylene (PP) has a melt index (MI) of 26 g / 10 min, a melting point of 176°C, and a moisture content of ≤500 ppm after drying. Polylactic acid (PLA) has a molecular weight of 5,000 to 70,000 g / mol and a melting point of 155 to 185°C. Polyetheretherketone (PEEK) has a molecular weight of 6,200 to 15,800 g / mol and a melting point of 330 to 350°C. Polyetherimide (PEI) has a molecular weight of 42,000 to 55,000 g / mol and a viscosity flow temperature of 280-300°C. Polycaprolactone (PCL) has a molecular weight of 5,000 to 40,000 g / mol and a melting point of 55 to 60°C. Polyglycolide PLGA (LA / GA = 90 / 10, 80 / 20, 75 / 25, 60 / 40, 50 / 50) has a molecular weight of 5,000 to 200,000 g / mol and a melting point of 50 to 70°C. Polyethylene (PE) has a molecular weight of 10,000 to 100,000 g / mol and a melting point of 105 to 110°C.

[0061] In step 1) of the present invention, the two-component polymer includes an inner layer component and an outer layer component, and the melting point of the inner layer component is higher than the melting point of the outer layer component. Optionally, the inner layer component is selected from polyetherimide or polyglycolide, and the outer layer component is selected from polyethylene or polylactic acid. Among them, in the inner layer component, polyetherimide (PEI) has a molecular weight of 42,000 to 55,000 g / mol and a viscosity flow temperature of 280-300°C. Polycaprolactone (PCL) has a molecular weight of 5,000 to 40,000 g / mol and a melting point of 55 to 60°C. Polyglycolide PLGA (LA / GA=90 / 10, 80 / 20, 75 / 25, 60 / 40, 50 / 50) has a molecular weight of 5,000 to 200,000 g / mol and a melting point of 50 to 70°C. The outer layer comprises polyethylene (PE) with a molecular weight of 10,000 to 100,000 g / mol and a melting point of 105-110°C, and polylactic acid (PLA) with a molecular weight of 5,000 to 70,000 g / mol and a melting point of 155 to 185°C.

[0062] In a specific embodiment, the inner layer component particles are first added to screw 1 and melted at a certain temperature, and the outer layer component particles are added to screw 2 and melted at a certain temperature, and then extruded through the die.

[0063] In step 1) of the present invention, the inner layer component accounts for 40% to 60% of the total mass of the inner layer component and the outer layer component, and can be optionally 40% to 50% or 50% to 60%.

[0064] In step 1) of the present invention, the radial thickness of the inner layer component is 0.04 to 0.48 mm, and can be 0.04 to 0.12 mm, 0.12 to 0.24 mm, 0.24 to 0.36 mm, or 0.36 to 0.48 mm. The radial thickness of the outer layer component is 0.04 to 0.48 mm, and can be 0.04 to 0.12 mm, 0.12 to 0.24 mm, 0.24 to 0.36 mm, or 0.36 to 0.48 mm.

[0065] The outer component has a low melting point, and the temperature for threading the hollow fiber is low. The inner component has a melting point higher than the threading temperature. During the threading process of the hollow fiber tube, no deformation occurs when heated, and it plays a good supporting role in the hollow structure. In addition, the depth of the thread is 0.02mm to 0.03mm, so the radial thickness of the outer component exceeds the thread depth. The above-mentioned radial thickness of the inner and outer layers is determined according to the size of the casing and the ratio of the inner and outer components.

[0066] In step 1) of the present invention, the outer diameter of the hollow die is 0.59 mm to 1.0 mm. It can be selected from 0.59 mm to 0.8 mm, 0.8 mm to 1.0 mm, 0.59 mm to 0.9 mm, 0.9 mm to 1.0 mm, 0.59 mm to 0.96 mm, or 0.96 mm to 1.0 mm. The inner diameter of the hollow die is 0.51 mm to 0.92 mm, and can be selected from 0.51 mm to 0.7 mm, 0.7 mm to 0.92 mm, 0.51 mm to 0.72 mm, 0.72 mm to 0.92 mm, 0.51 mm to 0.8 mm, 0.8 mm to 0.92 mm, 0.51 mm to 0.9 mm, 0.9 mm to 0.92 mm, 0.51 mm to 0.82 mm, or 0.82 mm to 0.92 mm. The opening spacing is 0.1 mm to 0.2 mm.

[0067] In step 1) of the present invention, the extrusion temperature is 110° C. to 380° C., and may be 110° C. to 140° C., 120° C. to 130° C., 120° C. to 240° C., 200° C. to 240° C., 245° C. to 255° C., 340° C. to 380° C., etc. The extrusion rate is 8 m / min to 10 m / min, and may be 8 m / min to 9 m / min or 9 m / min to 10 m / min, etc.

[0068] Specifically, the hollow die head can be, for example, a C-type, a double C-type, a triple C-type, etc.

[0069] In step 1) of the present invention, the cooling temperature in the cold air is 10°C to 20°C, which can be 10°C to 15°C, 15°C to 20°C, 15°C to 18°C, or 18°C ​​to 20°C.

[0070] In step 1) of the present invention, the water bath cooling temperature is 20°C to 80°C. It can be 20°C to 40°C, 40°C to 70°C, or 70°C to 80°C. In a specific embodiment, the water cooling is performed at a temperature of 70°C in the first stage and 20°C in the second stage.

[0071] In the method for preparing the micro cannula provided by the present invention, step 2) is to feed the hollow fiber tube into a fixture with threads, circumferentially wrap and radially extrude the outer surface of the hollow fiber tube to form a hollow fiber tube with external thread lines.

[0072] In step 2) of the present invention, Figure 2 The clamp includes a clamp base 2, a plurality of clamp guide rails 4 are provided on the clamp base 2, each of the clamp guide rails 4 is provided with a heating claw base 1 that can slide relative to the clamp guide rail 4, each heating claw base 1 is provided with a heating claw 3 converging toward the center of the circle, and the end of each heating claw 3 is provided with an arc groove 5 (such as Figure 25 ), when the clamp is in a clamping state, each of the arc grooves 5 is enclosed to form a circle, forming a circumferential coating and radial extrusion on the outer surface of the hollow fiber tube; the bottom of the arc groove 5 is provided with a single-line internal thread.

[0073] Among them, when the clamp is in the clamping state, in the single-line internal thread, the major diameter D1 of the thread is 0.3~1.0mm, which can be selected as 0.3~0.82mm, 0.82~1.0mm, 0.3~0.92mm, 0.92~1.0mm, 0.3~0.91mm, 0.91~1.0mm, 0.3~0.6mm, 0.6~1.0mm, etc. The thread diameter D2 is 0.27-0.98mm, and can be selected from 0.27-0.58mm, 0.58-0.98mm, 0.27-0.6mm, 0.6-0.98mm, 0.27-0.7mm, 0.7-0.98mm, 0.27-0.86mm, 0.86-0.98mm, 0.27-0.96mm, 0.96-0.98mm, 0.27-0.95mm, or 0.95-0.98mm. The pitch L1 is 0.1mm-0.2mm. The thread length L0 is 60-120mm. The length L of the heating claw along the axis of the fixture is 60-120mm, and can be selected from 60-65mm, 65-120mm, etc.

[0074] The thread diameter range is adjustable, which makes the pitch adjustable, and thus the depth of the thread formed on the surface when the hollow fiber tube is extruded can be controlled, which is convenient for fixing the binding wire during surgery. The pitch should be 1.2-3.0 times the diameter of the surgical binding wire, so that the binding wire can be better fixed during binding, which is safer and more reliable. The thread length is mainly determined by the length of the blood vessel during surgery, which can better fit.

[0075] In step 2) of the present invention, the number of heating claws is 3, and the arc groove is a 1 / 3 arc groove. The grooves on the top of the three heating claws form a complete circle, forming a circumferential coating and radial extrusion on the outer surface of the hollow fiber tube. Figure 3 Through the above process, the inner thread pattern of the groove is simultaneously engraved on the surface of the hollow fiber tube.

[0076] In step 2) of the present invention, the heating claws are heated to the processing temperature by the heating module. The heating temperature of the fixture is 90°C to 350°C, and can be 90°C to 160°C, 160°C to 350°C, 90°C to 200°C, 200°C to 350°C, 90°C to 250°C, 250°C to 350°C, 90°C to 300°C, or 300°C to 350°C. The dwell time is 0.1 to 0.3 seconds, and can be 0.1 to 0.2 seconds or 0.2 to 0.3 seconds.

[0077] In the method for preparing the micro cannula provided by the present invention, step 3) uses a cutter to cut the hollow fiber tube with external thread lines to obtain a micro cannula with external thread lines. Each cut section contains external thread lines.

[0078] In step 3) of the present invention, the tool comprises a cutting blade. Furthermore, the tool is provided with a plurality of grooves, and the cutting blades are distributed along the axial direction of the plurality of grooves, and the cutting blades are convex cutting blades. Figure 25 The cutting blade includes a double-edged horizontal blade, a three-edged horizontal blade, and multiple longitudinal blades. Each longitudinal blade is respectively arranged between the double-edged horizontal blade and the three-edged horizontal blade. The extension direction of the longitudinal blade is consistent with the axial extension direction of the tool. The double-edged horizontal blade and the three-edged horizontal blade are respectively arranged along the circumference of the tool and perpendicular to the axial direction of the tool. Preferably, the three-edged horizontal blade is arranged in three grooves, and the respective horizontal blades of the three-edged horizontal blade are evenly arranged along the circumference of the tool. The double-edged horizontal blade is arranged in two grooves, and the respective horizontal blades of the double-edged horizontal blade are arranged along the circumference of the tool. Optionally, two longitudinal blades are included, respectively arranged at the edges of the two grooves, and the distribution direction is parallel to the axial direction of the tool.

[0079] Furthermore, a plurality of cutouts are reserved on the hollow fiber tube; preferably, according to the target stepped sleeve shape, the reserved cutouts are cut on the surface of the hollow fiber tube, such as Figure 25 The figure shows a side view of a hollow fiber tube. The incisions include double-edged horizontal incisions, three-edged horizontal incisions, and vertical incisions. When cutting, the double-edged horizontal knife is aligned with the double-edged horizontal incision, the three-edged horizontal knife is aligned with the three-edged horizontal incision, and the vertical knife is aligned with the vertical incision.

[0080] Preferably, the thickness of the cutting blade is 90% to 98% of the wall thickness of the hollow fiber tube, the edge thickness of the cutting blade is 0.05 to 0.2 mm, and the spacing between the double-edged horizontal blade and the triple-edged horizontal blade is 2-3 mm.

[0081] During application, when the fixture is in the clamping state, the arc groove carves lines on the surface of the hollow tube, while the cutting blade in the tool cuts into the surface of the hollow fiber tube (not completely cut off), leaving a dividing edge to facilitate the subsequent separation of the continuous hollow fiber tube into several stepped tubes. The micro-cannula after cutting is several stepped tubes, such as Figure 4 As shown in a. Figure 6 b. The length of the long side can be, for example, 4-6 mm, and the length of the short side can be, for example, 3-5 mm.

[0082] The above-mentioned setting makes it easier to insert the cannula into the other end of the blood vessel. After the cannula is put on the first blood vessel, a vascular clamp is needed to clamp the blood vessel and the protruding part of the cannula to fix them. The protruding part is easier to clamp. If it is too short, the operation of connecting the cannula to the blood vessel will increase the difficulty, and the clamping difficulty will also increase.

[0083] In the method for preparing the micro cannula provided by the present invention, the cut cannula in step 4) is cleaned, dried, packaged, and sterilized.

[0084] In step 4) of the present invention, deionized water is used for washing. The washing temperature can be 55°C to 70°C, and can be 55°C to 60°C or 60°C to 70°C.

[0085] In step 4) of the present invention, the drying is performed by hot air or vacuum drying.

[0086] In step 4) of the present invention, the disinfection is one or more of ethylene oxide disinfection, electron beam radiation, and ultraviolet light.

[0087] Micro cannula

[0088] The present invention also provides a micro cannula, which is prepared by the method for preparing the micro cannula as described in the first aspect of the present invention.

[0089] The outer diameter of the prepared microtube is no greater than 1 mm. The microtube can be either a single-layer hollow fiber tube or a double-layer hollow fiber tube. The double-layer hollow fiber tube consists of two inner and outer layers. Its unique structure provides excellent support, allowing it to withstand greater pressure and stress without deformation or rupture.

[0090] use

[0091] The present invention also provides a method for preparing the aforementioned microcannula or its application in the biomedical field, specifically, for example, sleeve-type sutureless and ligature-type microvascular anastomosis surgeries.

[0092] In a specific application example, the hind limb of a donor Sprague Dawley (SD) rat is transplanted in situ to another recipient SD rat. The femoral artery and vein of the donor rat are carefully dissected, and the hind limb is cut off at the middle of the femur and flushed with heparinized saline (Sigma Aldrich, St. Louis, USA). The recipient hind limb is cut open at the 1 / 3 level, and the femoral vessels are dissected and clamped with two microvascular clips at the proximal end of the artery and vein. The vessels are cut after a certain length is reserved, and the hind limb is cut off at the middle of the femur. A 7-0 nylon thread is passed through the lateral wall of the femoral vein and knotted as a traction thread. The traction thread is passed through a sleeve, and the recipient femoral vein is pulled through the sleeve. The sleeve is held with a micro clamp, and the vein is turned over in a "sleeve" manner, with the intima turned outside and the adventitia covering the sleeve, and knotted and fixed with a 7-0 nylon thread. The femoral vein of the donor limb is pulled together in a horizontal direction in the form of intima-intima, and is knotted and fixed on the sleeve with a 7-0 nylon thread. The anastomosis of the femoral artery is the same as that of the femoral vein. The artery and vein clips are removed in turn, and the reperfusion of the vessels is confirmed. Finally, the donor limb is sutured to the muscle and skin of the recipient with 5-0 absorbable thread. After the operation, the rats are subcutaneously injected with 2 ml of sterile saline for fluid replacement, and are placed in a mouse cage with a heating pad for recovery. The health status of the recipient rats is monitored.

[0093] The beneficial effects of the present application are further illustrated in the following examples.

[0094] In order to make the inventive purpose, technical scheme and beneficial technical effects of the present application clearer, the present application is further described in detail in the following examples. However, it should be understood that the examples of the present application are only for the purpose of explanation, and are not intended to limit the present application, and the examples of the present application are not limited to the examples given in the specification. The specific experimental conditions or operation conditions in the examples are not specified, and are made according to the conventional conditions or the conditions recommended by the material suppliers.

[0095] In addition, it should be understood that the combination of one or more method steps mentioned in the present application does not exclude the presence of other method steps before and after the combination steps or the insertion of other method steps between the explicitly mentioned steps, unless otherwise stated; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present application does not exclude the presence of other devices / apparatuses before and after the combination devices / apparatuses or the insertion of other devices / apparatuses between the two explicitly mentioned devices / apparatuses, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the arrangement order of each method step or to limit the range of implementation of the present application, and the change or adjustment of the relative relationship without substantial change of the technical content is also regarded as the scope of implementation of the present application.

[0096] In the following examples, unless otherwise specified, various raw materials of the present invention can be purchased commercially or prepared according to conventional methods in the art.

[0097] Example 1:

[0098] Raw materials: polypropylene (PP), melt index MI = 26g / 10min, melting point 176°C, moisture content ≤ 500ppm after drying. Preparation steps:

[0099] 1. Add PP granules into the screw and melt at 250℃;

[0100] 2. The melt is extruded through a double C-shaped die at a temperature of 250°C. The micropores of the die are symmetrically double C-shaped, such as Figure 8 As shown, the outer diameter D3 = 0.59 mm, the inner diameter D4 = 0.51 mm, the opening spacing D5 = 0.1 mm, the extrusion rate is 10 m / min, and the melt stream after extrusion is cooled in air at 20°C to obtain a hollow fiber tube with an outer diameter of 0.6 mm and an inner diameter of 0.5 mm;

[0101] 3. Feed the hollow tube into the heated fixture with the major diameter of the fixture thread D1 = 0.6 mm, the minor diameter of the thread D2 = 0.58 mm, the length of the thread portion L0 = 65 mm, the pitch L1 = 0.1 mm, the fixture temperature 145 ° C, and the dwell time 1 s.

[0102] 4. Cutting: The long side length L2 of the sleeve is 6 mm and the short side length L3 is 3 mm.

[0103] 5. Cleaning and drying: Clean with deionized water at 95°C and dry in hot air at 120°C.

[0104] 6. Packaging and sterilization: Each set of 3 hollow fiber tubes is packaged and sterilized using ethylene oxide.

[0105] 7. The outer diameter d1 of the obtained PP sleeve is 0.6 mm, the inner diameter d2 is 0.5 mm, the long side length L2 is 6 mm, and the short side length L3 is 3 mm.

[0106] 8. The prepared microcannula of Example 1 was applied to rats, and the femoral artery and vein were anastomosed under microscope to construct an orthotopic transplantation model of rat lower limbs. At different time points, the changes in the levels of inflammatory factors and immune rejection-related cytokines in plasma and tissues surrounding the implant, changes in liver and kidney function indicators, and pathological histological changes in tissues surrounding the implant, liver, and kidneys were detected.

[0107] In vivo detection indicators:

[0108] 1) At 1 month and 6 months after surgery, the pericannula tissues were collected for H&E staining to observe the infiltration of lymphocytes, granulocytes, etc. and compared with the perivascular tissues of the control group.

[0109] 2) At 1 month and 6 months after surgery, the levels of IL-2, IL-10, TNF-α and IFN-γ in the tissue surrounding the cannula were measured and compared with those in the normal perivascular tissue.

[0110] 3) The levels of IL-2, IL-10, TNF-α and IFN-γ in the plasma of rats were compared with those in the control group at the 1st, 3rd and 6th month after surgery.

[0111] 4) At the first and sixth months after surgery, the rats' plasma was collected to measure liver function indicators such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and renal function indicators such as creatinine and urea. There was no significant difference in the liver and renal function indicators between the rats in the control group and the control group.

[0112] 5) At 1 month and 6 months after surgery, the average deposition density of IgG, IgM and C3c in the perivascular tissue of the cannula was measured and compared with that of the perivascular tissue of the control group.

[0113] 6) Six months after surgery, the liver and kidney tissues of the rats were collected for H&E staining and compared with those of the rats in the control group.

[0114] The microtubules were used in vivo to construct an orthotopic transplantation model in rat lower limbs. Figure 9 (Example 1 - Diagram of surgical steps for constructing an orthotopic transplantation model in SD rats using a PP cannula for in vivo implantation.) A. Isolate and expose the femoral vessels of the donor and recipient rats; B. Pass the traction line through the cannula; C. Flip the donor femoral vessel into a "cuff-like" position; D. Secure the cannula and insert the recipient femoral vessel; E. Anastomose the femoral vein; F. Complete femoral arteriovenous anastomosis.

[0115] After the experiment, the H&E staining of cell infiltration in the pericannula tissue at 1 month and 6 months after surgery showed no significant difference from that in the perivascular tissue of the control group. Figure 10 shown.

[0116] The levels of IL-2, IL-10, TNF-α, and IFN-γ in the perivascular tissues of the cannula at the 1st and 6th months after surgery were not significantly different from those in the perivascular tissues of the control group, as shown in Tables 1 and Figure 11 shown.

[0117] Table 1

[0118]

[0119]

[0120] There was no significant difference in the levels of IL-2, IL-10, TNF-α, and IFN-γ in the plasma of rats with cannula implantation and those of the control group at the 1st, 3rd, and 6th month after surgery, as shown in Table 2 andFigure 12 shown.

[0121] Table 2

[0122]

[0123] There was no significant difference in the liver and kidney function indicators between the plasma of the rats with cannula implantation and the control group at the 1st, 3rd and 6th month after surgery, as shown in Table 3. Figure 13 shown.

[0124] Table 3

[0125]

[0126]

[0127] The average deposition density of IgG, IgM and C3c in the perivascular tissue of the cannula at 1 month and 6 months after surgery was not significantly different from that in the perivascular tissue of the control group, as shown in Table 4. Figure 14 shown.

[0128] Table 4

[0129]

[0130] Six months after surgery, H&E staining of the liver and kidney tissues of the cannula-implanted rats showed no significant difference from those of the control rats. Figure 15 shown.

[0131] 9. Perform biocompatibility testing on the PP sleeve, including cytotoxicity test, coagulation test, hemolysis test, scratch test, bacterial reverse mutation test and in vitro mammalian cell chromosome aberration test.

[0132] (1) Preparation of PP casing extract

[0133] The cannula obtained in Example 1 of the present invention was chopped up in a clean bench. 0.9% sodium chloride injection was used as the extraction medium (RPMI-1640 culture medium was used for cell experiments). The cannula particles were extracted at a ratio of 0.2 g / ml in a 37°C constant temperature shaker for 72 hours. The resulting extract was filtered through a 0.22 μm bacterial filter and stored at 4°C until further use.

[0134] (2) Cytotoxicity test

[0135] The CCK-8 assay was used to measure the cytotoxicity of the extracts against exponentially growing L929 mouse fibroblasts. A negative control (normal culture medium), experimental groups (different concentrations of the cannula extract), and a positive control (1% phenol) were set up. Samples were removed after 1, 2, 3, and 4 days of culture and the absorbance (OD) values ​​of each group were measured using a microplate reader at 450 nm. The relative growth rate (RGR) was calculated based on the OD values ​​using the formula: RGR = sample OD value / negative control OD value. The cannulae were then assigned a cytotoxicity stage (CTS) based on the RGR values.

[0136] Observation of the OD values ​​of each group at 1, 2, 3, and 4 days revealed that, with the exception of the positive control group, the OD values ​​of all other groups gradually increased with prolonged incubation. The extracts of each concentration showed no significant differences compared to the negative control group over the same period (p>0.05), but showed significant differences compared to the positive control group (p<0.05), as shown in Table 5. Furthermore, the cytotoxicity of the extracts at all concentrations was below level 1, as shown in Table 6, meeting safety standards.

[0137] Table 5 Changes in OD values ​​of L929 cells in various concentrations of extracts, positive and negative controls

[0138]

[0139] Table 6 RGR and CTS of L929 cells in various concentrations of extracts, positive and negative controls

[0140]

[0141] (3) Coagulation test

[0142] 50, 100, and 200 mg of the cannula particles were added to normal mixed plasma, and the prothrombin time (PT), partial thromboplastin time (APTT), thrombin clotting time (TT), and fibrinogen were measured (Fig).

[0143] After adding different doses of PP cannula granular material, the plasma coagulation function indicators were normal, as shown in Table 7.

[0144] Table 7 Coagulation function after different doses of sheath granules

[0145]

[0146] (4) Hemolysis test

[0147] 5 mL each of normal saline (negative control group), distilled water (positive control group), and standard concentration extract (experimental group) were placed in a centrifuge tube. Three parallel controls were set up for each group and preheated in a 37°C constant temperature water bath for 30 minutes. 0.2 mL of diluted anticoagulated rabbit blood was added, shaken thoroughly, and incubated in a 37°C water bath for another 50 minutes before centrifugation. The supernatant was collected and the OD value was measured at a wavelength of 545 nm using a microplate reader. The hemolysis rate was calculated using the following formula: (mean OD value of the sample - mean OD value of the negative control) / (mean OD value of the positive control - mean OD value of the negative control).

[0148] After adding rabbit blood, the experimental and negative control groups showed a turbid red color, indicating no hemolysis. The positive control group showed a transparent red color, indicating hemolysis. The hemolysis rate of the PP cannula granules was 0.48%, lower than 5%, as shown in Table 8, meeting safety standards.

[0149] Table 8 OD value and hemolysis rate of the extract

[0150]

[0151] (5) Scratch test

[0152] Exponentially dividing L929 mouse fibroblasts were seeded in 6-well plates and cultured until the cells reached contact inhibition. A vertical streak was made with a pipette tip, and detached cells were washed off with phosphate buffer. The culture was continued for 24 hours. A negative control group (normal culture medium) and an experimental group (standard concentration cannula extract) were set up, with three replicates per group. Images of the scratch area in each group were taken at 0 and 24 hours using an inverted microscope, and the scratch area was statistically analyzed using Image J software.

[0153] The percentage of the remaining scratch area after 24 hours of scratching with the extract was not significantly different from that of the control group (p>0.05), and the cannula had no effect on the cell migration ability. Figure 7 shown.

[0154] Table 9 Percentage of remaining scratch area and migration rate

[0155]

[0156] (6) Bacterial reverse mutation test

[0157] Take the qualified TA98 and TA100 strains, add the growth culture medium in proportion and mix well to make a bacterial liquid growth mixture. Set up different concentration experimental groups (extracts), solvent control groups (sterile water) and positive control groups. Each group includes the use of metabolic activation system (+S9) and no metabolic activation system (-S9). Add samples according to the addition method shown in Table 10. After mixing each group, add it to a 96-well plate and culture it in a constant temperature incubator at 37°C. Add growth indicator after 24 hours, continue to culture for 48 hours, and observe the number of reverted colonies in each group.

[0158] Table 10 Bacterial reverse mutation test sample addition method

[0159]

[0160]

[0161] The number of revertant colonies of TA98 and TA100 strains with and without the metabolic activation system was less than 2 times that of the negative control group, indicating that the bacterial revert mutation test of PP material was negative, as shown in Table 11.

[0162] Table 11 Effect of PP materials on reverse mutation of mouse Escherichia coli

[0163]

[0164] Note: Positive control: -S9: TA98 is diphenhydramine, TA100 is sodium azide; +S9: TA98 is 2-aminofluorene, TA100 is cyclophosphamide

[0165] (7) In vitro mammalian cell chromosome aberration test

[0166] Take CHL cells that are in the exponential division phase and grow well on the wall and adjust the density to 1×10 6 Cells were cultured at 4% CO₂O / ml for 24 h. Experimental groups (extracts) with different concentrations, a solvent control group (sterile water), and a positive control group were set up. Each group included those using the metabolic activation system (+S9) and those not using the metabolic activation system (-S9). The samples were exposed to the poison according to the addition method shown in Table 12. Colchicine was added to each group 4 h before terminating the culture. After completion, cells were collected and counted, and chromosomal aberrations were observed and recorded under a microscope.

[0167] Table 12 Contamination treatment

[0168]

[0169]

[0170] As shown in Figure 13 and Figure 16As shown, the leaching liquor was contacted with CHL cells for 3 h with and without S9, and for 24 h without S9. The chromosomal aberration rate of the leaching liquor was not significantly different from that of the negative control group (p>0.05), but was significantly different from that of the positive control group (p<0.05), indicating that the material had no chromosomal aberration effect, as shown in Table 13.

[0171] Table 13 Effect of PP material on chromosomal aberration of mammalian cells in vitro

[0172]

[0173] Example 2:

[0174] For polymers with a high softening point, the surface grooving temperature is high, which affects the structure and performance of the sleeve. Therefore, a bicomponent hollow fiber tube is designed, which utilizes the different melting points of the two components. The outer layer has a low melting point, which is beneficial for surface grooving, and the inner layer has a high melting point, which is beneficial for supporting during grooving.

[0175] Raw materials: the inner layer component A is polyetherimide (PEI) with a molecular weight of 42000 g / mol, a viscous flow temperature of 280°C, and a water content of 0.01%-0.02%; the outer layer component B is PE with a molecular weight of 100000 g / mol, a melting point of 105°C, and a water content of <0.01%.

[0176] Preparation steps:

[0177] 1. Add component A particles to screw 1 and melt at a temperature of 300°C; add component B particles to screw 2 and melt at a temperature of 250°C;

[0178] 2. Extrude the melt through a C-shaped die with a die temperature of 28°C, a C-shaped die hole shape, an outer diameter size D3=0.90 mm, an inner diameter D4=0.60 mm, an opening distance D5=0.2 mm, an extrusion rate of 8 m / min, a mass ratio of component A to component B of 6:4, and cool the extruded stream in 15°C air to obtain a hollow tube with an outer diameter d1 of 0.99 mm and an inner diameter d2 of 0.55 mm, a radial thickness T1 of component A of 0.176 mm, and a radial thickness T2 of component B of 0.264 mm;

[0179] 3. Feed the hollow fiber tube into a clamp with a major diameter D1 of 0.99 mm, a minor diameter D2 of 0.92 mm, a threaded portion length L0 of 65 mm, a thread pitch L1 of 0.1 mm, a clamp temperature of 150°C, and a residence time of 0.5 s;

[0180] 4. Cutting: obtain a sleeve with a long side length L2 of 6 mm and a short side length L3 of 3 mm;

[0181] 5. Cleaning: Clean with ethanol at room temperature and vacuum dry at 50°C;

[0182] 6. Disinfection: 3 hollow fiber tubes are sealed as a set and sterilized by ultraviolet light;

[0183] 7. The outer diameter d1 of the obtained sleeve is 0.99 mm, the inner diameter d2 is 0.55 mm, the long side length L2 is 6 mm, and the short side length L3 is 3 mm.

[0184] 8. The PEI / PE cannula prepared in Example 2 was applied to rats, and the femoral artery and vein were anastomosed under microscope to construct an orthotopic rat lower limb transplantation model. The operation process was the same as in Example 1. At different time points, the levels of inflammatory factors and immune rejection-related cytokines in plasma and tissue surrounding the implant, changes in liver and kidney function indicators, and pathological changes in tissue surrounding the cannula and liver and kidney tissues were detected.

[0185] In vivo detection indicators:

[0186] 1) At 1 month and 3 months after surgery, the perivascular tissues of the cannula were collected for H&E staining to observe the infiltration of lymphocytes and granulocytes, and compared with the perivascular tissues of the control group.

[0187] 2) At 1 month and 3 months after surgery, the levels of IL-2, IL-10, TNF-α and IFN-γ in the perivascular tissue of the cannula were measured and compared with those in the perivascular tissue of the control group.

[0188] 3) The levels of IL-2, IL-10, TNF-α and IFN-γ in the peripheral plasma of rats were compared with those in the control group at the first and third months after surgery.

[0189] 4) At the first and third month after surgery, peripheral plasma of rats was collected to measure liver function indicators such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and renal function indicators such as creatinine and urea. There was no significant difference in the liver and renal function indicators between the rats in the control group and those in the control group.

[0190] 5) At the first and third month after surgery, the average deposition density of IgG, IgM, and C3c in the perivascular tissue of the cannula was measured and compared with that of the perivascular tissue of the control group.

[0191] 6) At 3 months after surgery, liver and kidney tissues of the rats were collected for H&E staining and histopathological comparison with those of the liver and kidney tissues of the rats in the control group.

[0192] After experiments, microtubes were used in vivo to construct an orthotopic transplantation model of rat lower limbs. Figure 17(Example 2 - Diagram of surgical steps for constructing an orthotopic transplant model in the lower limb of an SD rat using PEI / PE cannula implantation.) A. Dissection of the femoral artery and vein of the donor SD rat's lower limb; B. Dissection of the vessels along the dotted lines; C. Exposure of the donor and recipient femoral vessels; D. Cannula implantation in the femoral artery; E. Completion of femoral artery and vein anastomosis; F. Reperfusion of the graft.

[0193] There was no significant difference in cell infiltration between the pericannula tissue and the perivascular tissue of the control group in H&E staining at the 1st and 3rd month after surgery. Figure 18 shown.

[0194] The levels of IL-2, IL-10, TNF-α, and IFN-γ in the perivascular tissues of the cannula at the 1st and 3rd months after surgery were not significantly different from those in the perivascular tissues of the control group, as shown in Table 14. Figure 19 shown.

[0195] Table 14

[0196]

[0197] There was no significant difference in the levels of IL-2, IL-10, TNF-α and IFN-γ in the plasma of rats with implanted cannula and those of the control group at the 1st and 3rd month after surgery: as shown in Table 15, Figure 20 shown.

[0198] Table 15

[0199]

[0200] There was no significant difference in the liver and kidney function indicators between the plasma of the rats with implanted cannula and the control group at the 1st and 3rd month after surgery: as shown in Table 16 and Figure 21 shown.

[0201] Table 16

[0202]

[0203]

[0204] The average deposition density of IgG, IgM and C3c in the perivascular tissue of the cannula at the 1st and 3rd month after surgery was not significantly different from that in the perivascular tissue of the control group: as shown in Table 17 and Figure 22 shown.

[0205] Table 17

[0206]

[0207] Six months after surgery, H&E staining of the liver and kidney tissues of the cannula-implanted rats showed no significant difference from those of the control rats. Figure 23 shown.

[0208] 9. The obtained PEI / PE sleeve was subjected to in vitro compatibility testing, including cytotoxicity test, coagulation test, hemolysis test, scratch test, bacterial reverse mutation test, and in vitro mammalian cell chromosome aberration test. The experimental steps were the same as those in Example 1.

[0209] (1) CCK8 test

[0210] With the exception of the positive control group, the OD values ​​of all other groups gradually increased with prolonged incubation. The PEI / PE material extracts at all concentrations showed no significant differences compared to the negative control group (p>0.05) over the same period, but showed significant differences compared to the positive control group (p<0.05), as shown in Table 18. The cytotoxicity of the extracts was below level 1, as shown in Table 19.

[0211] Table 18 Changes in OD values ​​of L929 cells in various concentrations of PEI / PE extracts, positive and negative control solutions

[0212]

[0213] Table 19 RGR and CTS of L929 cells in various concentrations of PEI / PE extracts and positive control solutions

[0214]

[0215] (2) Hemolysis test

[0216] The PEI / PE test material and the negative control group were visibly red and turbid, indicating no hemolysis. The positive control group was transparent red, indicating hemolysis. The cannula granules had a hemolysis rate of 0.96%, which is lower than 5%, as shown in Table 20, meeting safety standards.

[0217] Table 20 Absorbance values ​​and hemolysis rates of cannula particles in each group

[0218]

[0219] (3) Coagulation test

[0220] After adding different doses of PEI / PE sleeve particle materials, the plasma coagulation function indicators were normal, as shown in Table 21.

[0221] Table 21 Coagulation function after different doses of cannula particles

[0222]

[0223] (4) Scratch test

[0224] The percentage of the remaining scratch area after 24 hours of scratching with PEI / PE extract was not significantly different from that of the control group (p>0.05), and the PEI / PE sleeve had no effect on the cell migration ability. ​ shown.

[0225] Table 22 Percentage of remaining scratch area and migration rate of extract

[0226]

[0227] (5) Bacterial reverse mutation test

[0228] As shown in Table 23, the number of revertant colonies of TA98 and TA100 strains with and without the metabolic activation system was less than 2 times the count of the negative control group, indicating that the bacterial revert mutation test of PEI / PE sleeve particles was negative, as shown in Table 23.

[0229] Table 23 Effect of PEI / PE sleeve particles on reverse mutation of mouse Escherichia coli

[0230]

[0231] (6) In vitro mammalian chromosome aberration test

[0232] As shown in Table 24 and ​ As shown in Table 24, the chromosome aberration rate of the PEI / PE extract in contact with CHL cells for 3 h with or without S9, and in contact with CHL cells for 24 h without S9, was not significantly different from that of the negative control group (p>0.05), but was significantly different from that of the positive control group (p<0.05), indicating that the cannula of Example 2 had no chromosome aberration-inducing effect, as shown in Table 24.

[0233] Table 24 Effects of PEI / PE sleeve particles on chromosome aberrations in mammalian cells in vitro

[0234]

[0235] Other examples are shown in Table 25.

[0236] Table 25 Examples of process parameters of other embodiments

[0237]

[0238]

[0239]

[0240]

[0241] Table 26 Summary of symbols in the full text

[0242]

[0243]

[0244] In summary, the present application effectively overcomes the shortcomings of the prior art and has a high industrial utilization value.

[0245] The above description is only the preferred embodiment of the present application, and is not any form of and substantial limitation on the present application. It should be noted that, for ordinary skilled in the art, without departing from the method of the present application, a number of improvements and supplements can also be made, which should be considered as the protection scope of the present application. For those skilled in the art, without departing from the spirit and scope of the present application, some changes, modifications and equivalent changes made by using the above disclosed technical content are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above-mentioned embodiments according to the essential technology of the present application are still within the scope of the technical solutions of the present application.

Claims

1. A method for preparing a micro cannula, characterized in that: The preparation method comprises the following steps: 1) The polymer is melted and extruded from a hollow die, and solidified in cold air or a water bath to form a continuous hollow fiber tube, wherein the outer diameter d1 of the hollow fiber tube is 0.3 to 1.0 mm and the inner diameter d2 is 0.2 to 0.9 mm; 2) feeding the hollow fiber tube into a fixture with threads, circumferentially coating and radially extruding the outer surface of the hollow fiber tube to form a hollow fiber tube with external thread patterns; 3) Using a cutter to cut the hollow fiber tube with external thread lines to obtain a micro cannula; 4) The cut micro cannula is cleaned, dried, packaged and sterilized.

2. The method for preparing the micro cannula according to claim 1, wherein: In step 1), the polymer is selected from a single-component polymer or a two-component polymer.

3. The method for preparing the micro cannula according to claim 2, wherein: Step 1) also includes any one or more of the following features: A1) the single-component polymer is selected from one of polypropylene, polyetheretherketone, polylactic acid, polyetherimide, polycaprolactone, polyglycolide, polylactic acid-co-glycolic acid, and polyethylene; A2) The two-component polymer comprises an inner layer component and an outer layer component, wherein the melting point of the inner layer component is higher than the melting point of the outer layer component.

4. The method for preparing the micro cannula according to claim 3, wherein: Step 1) also includes any one or more of the following features: A21) In feature A2), the inner layer component is selected from polyetherimide or polyglycolide, and the outer layer component is selected from polyethylene or polylactic acid; A22) In feature A2), the inner layer component accounts for 40% to 60% of the total mass of the inner layer component and the outer layer component; A23) In feature A2), the radial thickness of the inner layer component is 0.04 to 0.48 mm; the radial thickness of the outer layer component is 0.04 to 0.48 mm.

5. The method for preparing the micro cannula according to claim 1, wherein: Step 1) also includes any one or more of the following features: B1) In step 1), the outer diameter of the hollow die is 0.59 mm to 1.0 mm, the inner diameter is 0.51 mm to 0.92 mm, and the opening spacing is 0.1 mm to 0.2 mm; B2) in step 1), the extrusion temperature is 110° C. to 380° C.; B3) in step 1), the extrusion rate is 8 m / min to 10 m / min; B4) cooling in the cold air to a temperature of 10° C. to 20° C.; B5) The temperature of the water bath cooling is 20℃~80℃.

6. The method for preparing the micro cannula according to claim 1, wherein: In step 2), any one or more of the following features are also included: C1) The clamp comprises a clamp base (2), a plurality of clamp guide rails (4) are provided on the clamp base, each of the clamp guide rails (4) is provided with a heating claw base (1) that can slide relative to the clamp guide rail (4), each of the heating claw bases (1) is provided with a heating claw (3) that converges toward the center of a circle, and an arc groove (5) is provided at the end of each of the heating claws (3). When the clamp is in a clamped state, each of the arc grooves (5) encloses and forms a circle, forming a circumferential covering and radial extrusion on the outer surface of the hollow fiber tube; the bottom of the arc groove (5) is provided with a single-line internal thread; C2) The heating temperature of the fixture is 90° C. to 350° C., and the dwell time is 0.1 to 0.3 s.

7. The method for preparing the micro cannula according to claim 6, wherein: In step 2), when the fixture is in a clamped state, in the single-line internal thread, the major diameter D1 of the thread is 0.3-1.0 mm, the minor diameter D2 of the thread is 0.27-0.98 mm, the pitch L1 is 0.1 mm-0.2 mm; and the thread length is 60-120 mm.

8. The method for preparing a micro cannula according to claim 1, wherein: The method further comprises any one or more of the following features: D1) in step 3), the cutting tool comprises a cutting blade, wherein the cutting blade comprises a double-edged horizontal blade, a three-edged horizontal blade, and a plurality of longitudinal blades, each of the longitudinal blades being respectively disposed between the double-edged horizontal blade and the three-edged horizontal blade, the extension direction of the longitudinal blade being consistent with the axial extension direction of the tool, and the double-edged horizontal blade and the three-edged horizontal blade being respectively disposed along the circumference of the tool; preferably, the thickness of the cutting blade is 90% to 98% of the wall thickness of the hollow fiber tube, the blade thickness of the cutting blade is 0.05 to 0.2 mm, and the spacing between the double-edged horizontal blade and the three-edged horizontal blade is 2 to 3 mm; D2) In step 3), a plurality of incisions are reserved on the hollow fiber tube; preferably, the incisions include a double-edged horizontal incision, a three-edged horizontal incision and a longitudinal incision. D3) in step 4), washing with deionized water; D4) in step 4), the drying is hot air or vacuum drying; D5) In step 4), the sterilization is one or more of ethylene oxide sterilization, electron beam radiation, and ultraviolet light.

9. A micro cannula, characterized in that: The micro cannula is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the microcannula prepared by the method for preparing a microcannula according to any one of claims 1 to 8 or the microcannula according to claim 9 in the biomedical field.

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