Woven composite catheter and preparation method thereof

Abstract

The invention discloses a woven composite catheter and a preparation method thereof, and relates to the technical field of medical instruments, the catheter is sequentially and coaxially provided with an inner tube layer, an outer tube layer, an inner tube layer and an outer tube layer, the metal-polymer composite woven layer is formed by bidirectional interweaving of stainless steel wires and high-strength polyester fibers, and the metal-polymer composite woven layer is arranged at the pushing section and the bending section according to different weaving densities; the transition bonding layer is used for bonding the inner pipe layer and the woven layer through a hot melting polyamide copolymer PA11 / 12 co-extrusion process; the outer composite coating sequentially comprises a nano silicon dioxide reinforced polyurethane layer and a hydrophilic polyethylene glycol PEG modified coating; and platinum-iridium alloy imaging wires are pre-embedded at a preset number of turns of the woven layer, so that the integration of imaging and marking of the catheter is realized. By means of the variable-density metal-polymer composite woven layer, rigidity gradient adjustability is achieved, pushing force and flexibility are balanced, the problem that rigidity and flexibility of a single-density catheter are difficult to consider at the same time is solved, the turning passing rate is increased, and damage to the inner wall of a blood vessel is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, in particular to a braided composite catheter and a preparation method thereof. Background Art

[0002] With the increasing popularity of interventional therapies, minimally invasive catheters are placing higher demands on flexibility, thrust, imaging navigation, and functional integration. Traditional catheters lack adjustable stiffness, electromagnetic or metal markers, long-term lubrication, and multifunctional integration. These limitations make it difficult to balance precise navigation of complex vascular pathways with additional clinical demands, leading to the difficulty of achieving both stiffness and compliance with a single-density catheter.

[0003] Patent CN115227940B discloses a hybrid braiding method for composite catheter braids. By combining polymer materials with different types of metals, this patent not only improves the inherent structural properties of the medical composite catheter body, but also adds overall heating, local heating, electrical conductivity, indication, and magnetic guidance functions. This reduces the number of medical devices that need to enter the human body within limited cavities, providing a wider range of surgical options. This greatly facilitates medical personnel's operations and can also prevent medical accidents through the design of the catheter structure itself.

[0004] The composite catheter tube body described in the above patent is composed of an inner layer, a braided layer and an outer layer from the inside to the outside; the braided layer is mixed with braided wires of two different materials, and the two different mixed braided wire materials are easy-to-melt polymer material and high-resistance alloy material or easy-to-melt polymer material and enameled metal material or easy-to-melt polymer material and enameled alloy material or easy-to-melt polymer material and high-conductivity metal material or easy-to-melt polymer material and non-meltable developable polymer material / metal material; by mixed braiding of the braided wires of the above five groups of materials, different functions can be given to the catheter respectively, but the stiffness gradient cannot be adjusted, and the pushing force and flexibility requirements cannot be balanced.

[0005] To this end, the present application proposes a braided composite catheter and a preparation method thereof that can achieve adjustable stiffness gradient and balance the pushing force and flexibility requirements. Summary of the Invention

[0006] The object of the present invention is to provide a braided composite catheter and a method for preparing the same, so as to solve the technical problem in the above-mentioned background art that it is difficult to simultaneously achieve both stiffness and compliance in a single-density catheter.

[0007] To achieve the above object, the present invention provides the following technical solution: a braided composite catheter, wherein the catheter is coaxially provided with:

[0008] The inner tube layer is a polytetrafluoroethylene (PTFE) extruded lining;

[0009] The metal-polymer composite braided layer is formed by bidirectional interweaving of stainless steel wire and high-strength polyester fiber, and is set with different braiding densities in the pushing section and the bending section;

[0010] The transition bonding layer is used to bond the inner tube layer to the braided layer through the hot-melt polyamide copolymer PA11 / 12 co-extrusion process;

[0011] The outer composite coating comprises a nano-silica reinforced polyurethane layer and a hydrophilic polyethylene glycol (PEG) modified coating in sequence;

[0012] The braided layer is pre-embedded with platinum-iridium alloy imaging wires at predetermined turns to achieve integrated catheter imaging marking.

[0013] Preferably, the weaving density of the pushing section is 24×24, and the weaving density of the bending section is 12×12.

[0014] Preferably, the platinum-iridium alloy imaging wire has a diameter of 0.08 mm to 0.12 mm and is respectively arranged at the 80th and 200th turns of the braided layer.

[0015] Preferably, the thickness of the nano-silica reinforced polyurethane layer is 20 μm-50 μm, and the mass fraction of silica is 3%-7%.

[0016] Preferably, the molecular weight of the hydrophilic polyethylene glycol (PEG) modified coating is 5 kDa-15 kDa, and the coating thickness is 3 μm-8 μm.

[0017] Preferably, the catheter further comprises a functionalized partitioned coating located on the surface of the outer composite coating for local controlled drug release, wherein the functionalized partitioned coating is formed by spraying a drug-containing polymer.

[0018] Preferably, the drug-containing polymer is poly(lactic-co-glycolic acid) copolymer (PLGA) and is loaded with anticoagulant or antibacterial drugs.

[0019] Preferably, the outer diameter of the inner tube layer is 0.7 mm-1.2 mm, and the inner diameter is 0.6 mm-1.0 mm.

[0020] Preferably, the preparation method comprises the following steps:

[0021] Inner tube preparation steps: PTFE raw materials are extruded, stretched and tempered to produce an inner liner tube with an outer diameter of 0.7mm-1.2mm and an inner diameter of 0.6mm-1.0mm;

[0022] Braiding steps: Stainless steel wire and high-strength polyester wire are fed into a CNC braiding machine and braided according to a density program of 24×24 for the push section and 12×12 for the bend section. Platinum-iridium alloy imaging wires with a diameter of 0.08mm-0.12mm are embedded at the 80th and 200th turns.

[0023] Composite bonding step: The inner tube layer and the braided layer are fed into the PA11 / 12 co-extruder at the same time, and the hot melt co-extrusion process is used to firmly bond the two;

[0024] Outer coating steps:

[0025] (a) extrusion coating of polyurethane containing 3%-7% nano-SiO2 and curing to a coating thickness of 20μm-50μm;

[0026] (b) spray coating of a PEG-modified coating with a molecular weight of 5 kDa to 15 kDa and curing to a thickness of 3 μm to 8 μm;

[0027] Functionalized zoned spraying step: using a template and a microinjection pump to spray a polymer containing PLGA and drugs on specific sections of the catheter;

[0028] Testing and sterilization steps: Testing of inner and outer diameters, bending stiffness, tensile strength, lubricity and X-ray imaging performance, followed by ethylene oxide sterilization and packaging.

[0029] Preferably, the inner tube stretching temperature is 350℃-380℃; the PA11 / 12 co-extrusion temperature is 240℃-280℃, and the extrusion pressure is 1.0MPa-2.0MPa; the polyurethane and SiO2 mixing ratio is 93:7-97:3, the extrusion coating curing temperature is 80℃-100℃, and the time is 1.5h-2.5h; the PEG coating curing temperature is 40℃-60℃, and the time is 0.5h-1.5h; the ethylene oxide sterilization conditions are temperature 37℃-55℃, and time 6h-12h.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention uses a variable-density metal-polymer composite braided layer to achieve adjustable stiffness gradient, balancing pushing force and compliance. This solves the problem of single-density catheters being difficult to achieve both stiffness and compliance, improves cornering efficiency, and reduces damage to the vascular lining.

[0032] 2. This invention uses pre-embedded platinum-iridium alloy integrated imaging markers to achieve high-contrast positioning under X-rays, eliminating the need for post-bonding and enabling real-time navigation. This solves the problem of marker rings falling off or requiring secondary bonding, enhances intraoperative navigation accuracy, and shortens surgical time.

[0033] 3. This invention uses a double-layer composite coating of nano-SiO2-PU and PEG to achieve both wear-resistant protection and long-lasting lubrication, significantly reducing the surface friction coefficient. This solves the problems of single-layer coatings easily falling off and short lubrication duration, extending the life of the catheter, reducing propulsion resistance, and lowering the risk of vascular damage.

[0034] 4. The present invention realizes localized efficient drug delivery and customized antibacterial hemostasis through functional partitioned drug loading and modular spraying of antibacterial and hemostatic coatings, solves the problem of difficulty in integrating functional drug delivery or antibacterial hemostasis into catheters, meets personalized clinical needs, reduces postoperative complications, and improves treatment effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the catheter hierarchical distribution of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Example 1, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0038] Inner tube preparation:

[0039] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0040] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0041] Preparation process:

[0042] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: 24×24 bidirectional weaving density at 150mm in the push section, 12×12 density at 50mm in the bend section;

[0043] Tension control: Initial tension of stainless steel wire is 0.5N, tension of polyester wire is 0.2N; Density switching: The braiding machine is preset with programs A (24×24) and B (12×12), which are automatically switched by PLC, with a transition section length of 10mm;

[0044] Co-extrusion compounding:

[0045] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0046] PA11 / 12 barrel temperature zone: 260°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braided layer;

[0047] Control group 1: commercially available PTFE-lined catheter (0.9 mm outer diameter, 0.8 mm inner diameter), no braided layer, and single-layer PU coating.

[0048] Test items:

[0049] 1. Bending stiffness (N·mm): using a three-point bending tester, span 30mm, loading rate 10mm / min;

[0050] 2. Pushing force (N): Push the catheter in a curved path (radius 20 mm) that simulates a blood vessel at a speed of 20 mm / s, and record the peak pushing force.

[0051] The results are shown in Table 1: Test table of the effect of variable braiding density on bending stiffness and pushing force:

[0052] Table 1 Test table of the effect of variable braiding density on bending stiffness and pushing force

[0053] Group Bending stiffness Peak pushing force Blank control group 1 0.6±0.05 2.0±0.1 Example 1 Experimental Group 1.25±0.08 3.2±0.15

[0054] Analysis: Due to the variable braiding density, the pushing section of the implementation group has improved rigidity and the bending section has maintained flexibility, making the pushing smoother and the turning more stable than the control group.

[0055] Example 2, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0056] Inner tube preparation:

[0057] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0058] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0059] Preparation process:

[0060] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: Bidirectional weaving with a density of 24×24 at the 150mm push section and a density of 12×12 at the 50mm bend section; A ψ0.10mm platinum-iridium alloy wire is embedded in the 80th and 200th turns;

[0061] Tension control: Initial tension for stainless steel wire is 0.5N, and for polyester wire is 0.2N. Density switching: The braiding machine is pre-set to programs A (24×24) and B (12×12), with automatic switching via the PLC. The transition length is 10mm. Implantation of the imaging wire: The PLC automatically pauses for 5 seconds at the 80th and 200th turns. The platinum-iridium wire is inserted manually or with the automatic wire swing device, firmly bonding it to the braid.

[0062] Co-extrusion compounding:

[0063] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0064] PA11 / 12 barrel temperature zone: 260°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braided layer;

[0065] Control group 2: commercially available PTFE-lined catheter (0.9 mm outer diameter, 0.8 mm inner diameter), no braided layer, single-layer PU coating;

[0066] Test items:

[0067] 1. X-ray imaging contrast: Take photos under the X-ray C-arm and evaluate the image clarity according to ISO 10993 standard (level 1-5);

[0068] 2. Marking position accuracy: Measure the deviation of the marking wire in the axial position of the catheter (mm), n = 10.

[0069] The results are shown in Table 2: X-ray visibility comparison test of integrated imaging markers:

[0070] Table 2 X-ray visibility comparison test table of integrated imaging markers

[0071] Group Imaging contrast level Position deviation Blank control group 2 - - Example 2 Experimental Group 4.2±0.3 0.5±0.1

[0072] Analysis: The integrated group marking method eliminates the need for post-bonding, resulting in clear and reliable imaging with a positional deviation of less than 1 mm.

[0073] Example 3, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0074] Inner tube preparation:

[0075] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0076] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0077] Preparation process:

[0078] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: 24×24 bidirectional braiding density at 150mm in the push section, 12×12 density at 50mm in the bend section; Tension control: Initial tension of stainless steel wire 0.5N, polyester yarn tension 0.2N; Density switching: The braiding machine has preset programs A (24×24) and B (12×12), which are automatically switched via the PLC; the transition section length is 10mm;

[0079] Co-extrusion compounding:

[0080] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0081] PA11 / 12 barrel temperature zone: 260°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braided layer;

[0082] Outer coating:

[0083] Layer A (nano-SiO2-PU): Add 5% mass fraction of nano-SiO2 to the polyurethane base liquid, extrusion coating thickness 35μm, and cure at 80℃×2h;

[0084] Layer B (PEG hydrophilic coating): PEG (molecular weight 10 kDa) was dissolved in ethanol-water solution, sprayed to a thickness of 6 μm, and low-temperature cured at 40°C for 1 h;

[0085] The distance between the extrusion head and the catheter for layer A was 2 mm, and the extrusion flow rate was controlled at 0.02 mL / min. The curing oven program was as follows: heating to 80°C (10 min), holding for 2 h, and cooling naturally to room temperature. The spraying pressure for layer B was 1.5 bar, the spray distance was 150 mm, the blade speed was 20 mm / s, and the number of spray cycles was 3. The curing was carried out at 40°C for 1 h.

[0086] Control group 3: commercially available PTFE-lined catheter (0.9 mm outer diameter, 0.8 mm inner diameter), no braided layer, single-layer PU coating.

[0087] Test items:

[0088] Surface friction coefficient (μ), using saline lubrication, the metal wire slides in the lumen test, the tensile speed is 5mm / s;

[0089] The results are shown in Table 3: Test table of the influence of double-layer composite coating on friction coefficient:

[0090] Table 3 Test table of the influence of double-layer composite coating on friction coefficient

[0091] Group Friction coefficient Blank control group 3 0.065±0.005 Example 3 Experimental Group 0.028±0.003

[0092] Analysis: The double-layer coating significantly reduces the friction coefficient, improves lubricity by >2 times, and reduces the risk of vascular wall damage.

[0093] Example 4, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0094] Inner tube preparation:

[0095] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0096] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0097] Preparation process:

[0098] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: Bidirectional weaving with a density of 24×24 at the 150mm push section and a density of 12×12 at the 50mm bend section; A ψ0.10mm platinum-iridium alloy wire is embedded in the 80th and 200th turns;

[0099] Tension control: Initial tension for stainless steel wire is 0.5N, and for polyester wire is 0.2N. Density switching: The braiding machine is pre-set to programs A (24×24) and B (12×12), with automatic switching via the PLC. The transition length is 10mm. Implantation of the imaging wire: The PLC automatically pauses for 5 seconds at the 80th and 200th turns. The platinum-iridium wire is inserted manually or with the automatic wire swing device, firmly bonding it to the braid.

[0100] Co-extrusion compounding:

[0101] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0102] PA11 / 12 barrel temperature zone: 260°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braided layer;

[0103] PLGA loaded with camptothecin was sprayed on the 100-120 mm section of the outer composite coating, with a drug loading of 100 μg / cm 2 ;

[0104] Control group 4: the catheter of Example 1, without a drug layer.

[0105] Test items: In vitro release curve: Place in PBS (pH 7.4) at 37°C, take samples continuously for 72 hours, and measure the camptothecin concentration (UV absorption method);

[0106] result:

[0107] The cumulative release rate of the experimental group of Example 4 over 72 hours was 68.5%±3.2%; the initial 24-hour release rate was 32.1%±2.5%.

[0108] Analysis: The zonal release in the implementation group was well controlled, meeting the needs of short-range local administration; there was no drug release in the control group.

[0109] Example 5, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0110] Inner tube preparation:

[0111] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0112] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0113] Preparation process:

[0114] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: 24×24 bidirectional braiding density at 150mm in the push section, 12×12 density at 50mm in the bend section; Tension control: Initial tension of stainless steel wire 0.5N, polyester yarn tension 0.2N; Density switching: The braiding machine has preset programs A (24×24) and B (12×12), which are automatically switched via the PLC; the transition section length is 10mm;

[0115] Co-extrusion compounding:

[0116] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0117] PA11 / 12 barrel temperature zone: Group A 240°C / Group B 260°C / Group C 280°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braid layer;

[0118] Control group 5: the catheter of Example 1, without PA co-extrusion test.

[0119] Test items:

[0120] Interlayer peel strength (N / cm), measured according to ASTM D1876;

[0121] The results are shown in Table 5. Test table of the effect of PA co-extrusion temperature on bonding strength:

[0122] Table 5 Test table of the effect of PA co-extrusion temperature on bonding strength

[0123]

[0124]

[0125] Analysis: The strongest bonding occurs at 260°C; too low or too high a temperature will reduce the interlayer bonding performance.

[0126] Example 6, please refer to Figure 1 : A method for preparing a braided composite catheter, used for preparing a braided composite catheter:

[0127] Inner tube preparation:

[0128] Materials: Commercial medical-grade PTFE pellets (melt index 5 g / 10 min). Process: Extruded in an extruder at 380°C and 5 MPa screw pressure to produce a PTFE tube with an outer diameter of 1.0 mm and an inner diameter of 0.8 mm. This tube was then cold-stretched in a stretcher at a speed of 4 mm / s and a draw ratio of 3:1, followed by tempering at 200°C for 2 h to eliminate internal stresses.

[0129] Extrusion temperature range: The barrel heating zones from the feed port to the die were set at 370°C, 380°C, and 390°C, respectively; the screw speed was 45 rpm; cooling: the inner tube was maintained at 25°C in a water bath with a water flow rate of 0.8 m / s; stretching: the stretch ratio was 3:1, the stretching speed was 4 mm / s, and after stretching, the tube was placed in a tempering furnace at 200°C for 2 hours.

[0130] Preparation process:

[0131] Wire material: 316L stainless steel wire ψ0.10mm and high-strength polyester fiber ψ0.08mm; Braiding machine: Six-axis CNC braiding machine; Parameters: Bidirectional weaving with a density of 24×24 at the 150mm push section and a density of 12×12 at the 50mm bend section; A ψ0.10mm platinum-iridium alloy wire is embedded in the 80th and 200th turns;

[0132] Tension control: Initial tension for stainless steel wire is 0.5N, and for polyester wire is 0.2N. Density switching: The braiding machine is pre-set to programs A (24×24) and B (12×12), with automatic switching via the PLC. The transition length is 10mm. Implantation of the imaging wire: The PLC automatically pauses for 5 seconds at the 80th and 200th turns. The platinum-iridium wire is inserted manually or with the automatic wire swing device, firmly bonding it to the braid.

[0133] Co-extrusion compounding:

[0134] Adhesive: PA11 / 12 copolymer, melt index 12g / 10min; Process: The inner tube and braided layer are fed into a co-extruder at 260°C, 1.5MPa, and 0.5m / min, forming a three-layer structure in one step.

[0135] PA11 / 12 barrel temperature zone: 260°C, pressure in the mold front holding zone 1.5MPa, back pressure 0.3MPa; due to the line speed of 0.5m / min, the melt residence time must be ≈8s to fully penetrate the inner tube and braided layer;

[0136] Sterilization:

[0137] Ethylene oxide at 37°C for 6 hours, residual gas <10ppm;

[0138] Control group 6: catheter according to Example 1, not sterilized.

[0139] Test items:

[0140] 1. Bending stiffness and pushing force (same as Example 1);

[0141] 2. Coating integrity inspection: surface SEM observation;

[0142] 3. Cytocompatibility: L929 fibroblasts were used to determine the 24-hour survival rate using the MTT assay.

[0143] The results are shown in Table 6, which shows the comprehensive evaluation test table of the effect of ethylene oxide sterilization on the performance of the catheter:

[0144] Table 6 Comprehensive evaluation test table of ethylene oxide sterilization on catheter performance

[0145]

[0146]

[0147] Analysis: Ethylene oxide sterilization has minimal effect on the mechanical and coating properties of the catheter, and has good biocompatibility, meeting the requirements of medical devices.

[0148] The list of public equipment and materials to be prepared includes:

[0149] Extrusion equipment: twin-screw extruder (model: JSW ZSE-27); stretching machine (model: GT-701); co-extruder (model: KraussMaffei ZE20 / 40);

[0150] Braiding machine: six-axis CNC braiding machine (model: AGRU TK-6);

[0151] Coating system: High-precision sprayer (model: Nordson EFD Ultimus V) and extrusion coating head (diameter 0.5mm);

[0152] Curing oven: programmable box oven (model: Memmert UFP800);

[0153] Testing instruments: digital universal tensile testing machine (INSTRON 5944), three-point bending test fixture, optical microscope (Olympus BX53), scanning electron microscope (SEM, Hitachi S-4800), X-ray visualization device (Siemens Artis Q);

[0154] Raw materials: medical-grade PTFE, UHMWPE, PVDF and other inner tube materials; 316L, Nitinol, cobalt-chromium alloy wire; high-strength polyester, aramid, Kevlar fiber; PA11 / 12, PEBA copolymer; medical-grade polyurethane and nano-SiO2; PEG (molecular weight 5k-15kDa); PLGA (50:50); various active drug molecules.

[0155] Conduct performance testing and quality inspection on batch-produced composite pipes;

[0156] The performance test methods and results are as follows:

[0157] 1. Geometric dimension measurement

[0158] Instrument: three-point contact caliper;

[0159] Method: Take 5 samples from each example, measure the outer diameter and inner diameter at room temperature, and take the average value.

[0160] 2. Bending stiffness test

[0161] Instrument: INSTRON 5944 digital tensile testing machine with three-point bending fixture;

[0162] Methods: A vertical force was applied to the middle section of the catheter at a loading speed of 1 mm / min, and the torque corresponding to 1.0 mm displacement was recorded.

[0163] 3. Pull-out force test

[0164] Instrument: Same as above testing machine;

[0165] Method: Clamp the inner tube and the braided layer separately, stretch them at a rate of 50 mm / min, and record the peak force when delamination occurs.

[0166] 4. Lubrication continuity

[0167] Equipment: Bionic vascular propulsion gantry;

[0168] Methods: The catheter was pushed back and forth in PBS lubricant for 3 times and then stopped. The maximum time that the pushing force remained below 1N was recorded.

[0169] 5. X-ray imaging contrast

[0170] Equipment: Siemens Artis Q digital subtraction angiography system

[0171] Methods: Films were taken at 50 kV / 200 mA and graded using a standard grayscale card (1-5).

[0172] 6. Drug release test

[0173] Method: The drug-coated section was immersed in a 37°C PBS shaker (50 rpm). Samples were taken after 30 minutes. The drug concentration was determined by HPLC and the cumulative release percentage was calculated.

[0174] 7. Antibacterial test

[0175] Methods: Plate diffusion method was used to test the diameter of the inhibition zone of Escherichia coli and calculate the inhibition rate.

[0176] 8. Hemostatic performance test (Example 6)

[0177] Model: Isolated porcine artery model;

[0178] Methods: The tip of the catheter was brought into contact with the perforated blood vessel, and the time required for hemostasis was recorded.

[0179] Table 7 Performance test results

[0180]

[0181] Note: “-” indicates that the corresponding functional test is not designed for this embodiment; each data is the mean + standard deviation.

[0182] Working Principle: This catheter utilizes a polytetrafluoroethylene (PTFE) inner tube to provide a base flow channel. The metal-polymer composite braided layer, with varying braid densities in the push and bend sections, creates a stiffness gradient. The outermost composite coating achieves a balance between lubrication and structural protection. The inner, braided, and outer layers work in close coordination, ensuring smooth catheter advancement during surgery while maintaining excellent flexibility and fatigue resistance.

[0183] Platinum-iridium alloy wires are embedded in the braid layer, allowing imaging markers to be braided and fixed to the structural layer simultaneously, eliminating the need for post-bonding. When exposed to X-rays, the platinum-iridium wires present high-contrast images, providing real-time indication of the catheter's position and bend boundaries, improving navigation accuracy and reducing the risk of secondary positioning operations.

[0184] The outer layer, a nano-SiO2-PU reinforced coating, provides wear resistance and structural support, while the second layer, a hydrophilic PEG coating, maintains long-lasting lubrication. The two coatings complement each other through the affinity of their different materials, achieving a combination of scratch resistance and low friction, minimizing damage to the blood vessel wall and extending lubrication duration.

[0185] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A braided composite catheter, characterized by: The conduit is coaxially provided with: The inner tube layer is a polytetrafluoroethylene (PTFE) extruded lining; The metal-polymer composite braided layer is formed by bidirectional interweaving of stainless steel wire and high-strength polyester fiber, and is set with different braiding densities in the pushing section and the bending section; The transition bonding layer is used to bond the inner tube layer to the braided layer through the hot-melt polyamide copolymer PA11 / 12 co-extrusion process; The outer composite coating comprises a nano-silica reinforced polyurethane layer and a hydrophilic polyethylene glycol (PEG) modified coating in sequence; The braided layer is pre-embedded with platinum-iridium alloy imaging wires at predetermined turns to achieve integrated catheter imaging marking.

2. The braided composite catheter according to claim 1, characterized in that: The weaving density of the pushing section is 24×24, and the weaving density of the bending section is 12×12.

3. The braided composite catheter according to claim 1, characterized in that: The platinum-iridium alloy imaging wire has a diameter of 0.08 mm to 0.12 mm and is respectively arranged at the 80th and 200th turns of the braided layer.

4. The braided composite catheter according to claim 1, characterized in that: The thickness of the nano-silicon dioxide reinforced polyurethane layer is 20 μm-50 μm, and the mass fraction of silicon dioxide is 3%-7%.

5. The braided composite catheter according to claim 1, characterized in that: The molecular weight of the hydrophilic polyethylene glycol (PEG) modified coating is 5 kDa-15 kDa, and the coating thickness is 3 μm-8 μm.

6. The braided composite catheter according to claim 1, characterized in that: The catheter further comprises a functionalized partitioned coating located on the surface of the outer composite coating for local controlled drug release, wherein the functionalized partitioned coating is formed by spraying a drug-containing polymer.

7. The braided composite catheter according to claim 6, characterized in that: The drug-containing polymer is polylactic acid-glycolic acid copolymer PLGA and is loaded with anticoagulant or antibacterial drugs.

8. The braided composite catheter according to claim 1, characterized in that: The outer diameter of the inner tube layer is 0.7 mm-1.2 mm, and the inner diameter is 0.6 mm-1.0 mm.

9. A method for preparing a braided composite catheter, applicable to the braided composite catheter according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: Inner tube preparation steps: PTFE raw materials are extruded, stretched and tempered to produce an inner liner tube with an outer diameter of 0.7mm-1.2mm and an inner diameter of 0.6mm-1.0mm; Braiding steps: Stainless steel wire and high-strength polyester wire are fed into a CNC braiding machine and braided according to a density program of 24×24 for the push section and 12×12 for the bend section. Platinum-iridium alloy imaging wires with a diameter of 0.08mm-0.12mm are embedded at the 80th and 200th turns. Composite bonding step: The inner tube layer and the braided layer are fed into the PA11 / 12 co-extruder at the same time, and the hot melt co-extrusion process is used to firmly bond the two; Outer coating steps: (a) Extrusion coating of polyurethane containing 3%-7% nano-SiO2 and curing to a coating thickness of 20μm-50μm; (b) Spray coating of PEG-modified coating with molecular weight of 5 kDa-15 kDa and curing to a thickness of 3 μm-8 μm; Functionalized zoned spraying step: using a template and a microinjection pump to spray a polymer containing PLGA and drugs on specific sections of the catheter; Testing and sterilization steps: Testing of inner and outer diameters, bending stiffness, tensile strength, lubricity and X-ray imaging performance, followed by ethylene oxide sterilization and packaging.

10. The method for preparing a braided composite catheter according to claim 9, characterized in that: The inner tube stretching temperature is 350℃-380℃; the PA11 / 12 co-extrusion temperature is 240℃-280℃, and the extrusion pressure is 1.0MPa-2.0MPa; the polyurethane and SiO2 mixing ratio is 93:7-97:3, the extrusion coating curing temperature is 80℃-100℃, and the time is 1.5h-2.5h; the PEG coating curing temperature is 40℃-60℃, and the time is 0.5h-1.5h; the ethylene oxide sterilization conditions are a temperature of 37℃-55℃ and a time of 6h-12h.

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