An intracranial thrombus aspiration catheter and its preparation method

Abstract

The present invention discloses an intracranial thrombus aspiration catheter and its preparation method, belonging to the technical field of medical devices. The catheter includes a PTFE inner liner, a reinforcing layer (including a coil layer and a braided layer), a segmented outer plastic layer, a platinum-iridium alloy radiopaque ring, and a coating. The preparation method includes PTFE inner liner extrusion, coil winding, braided layer covering, segmented plastic layer forming, radiopaque ring embedding and fixing, as well as coating treatment and surface functionalization. Compared with the prior art, the present invention significantly improves the coating adhesion and prevents peeling by optimizing the coating formula and process. At the same time, it enhances the surface hydrophilicity, reduces thrombus adhesion, and improves blood compatibility and operational performance. In addition, the multi-layer structure design improves the flexibility, anti-kinking property and anti-collapse ability of the catheter, ensuring its stability and effectiveness in complex vascular environments.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to an intracranial thrombus aspiration catheter and a preparation method thereof. Background Art

[0002] An intracranial thrombus aspiration catheter is a key medical device for treating acute ischemic stroke. Acute ischemic stroke is caused by thrombosis or embolism in large intracranial blood vessels (such as the internal carotid artery, middle cerebral artery, basilar artery, and vertebral artery), leading to cerebral ischemia. In severe cases, it can cause permanent brain damage or even death. Timely restoration of blood flow is the key to treatment, and the intracranial thrombus aspiration catheter has become an important treatment means by removing thrombus through mechanical aspiration.

[0003] Although the existing intracranial thrombus aspiration catheters have achieved certain results in clinical applications, there are still some technical bottlenecks and deficiencies, which limit their further application and development. First, the coating adhesion of the existing catheters is insufficient and is prone to peeling off in a complex vascular environment. This not only affects the performance of the catheter but also may cause complications such as thrombus residue or vascular injury. Second, the hydrophilicity of the catheter surface is poor, making it difficult to effectively reduce thrombus adhesion and improve blood compatibility, resulting in increased thrombus adhesion, affecting the aspiration effect, and thus reducing the treatment success rate. In addition, the intracranial vascular structure is complex, and the flexibility and anti-kinking ability of the existing catheters are insufficient, making it difficult to ensure smooth passage through the blood vessels and reaching the target position, which may cause the catheter to get stuck or kink in the blood vessels, affecting the treatment effect. Finally, during the aspiration process, the catheter needs to withstand a certain negative pressure, and the anti-collapse ability of the existing catheters is insufficient, which may cause the catheter to deform or block, reducing the aspiration efficiency and increasing the pain and treatment risk of the patient.

[0004] Although some improvement measures in the prior art have solved the above problems to a certain extent, there are still obvious limitations. For example, although some coating technologies have improved the adhesion, they often sacrifice hydrophilicity or other properties, resulting in increased thrombus adhesion and instead affecting the use effect of the catheter. In addition, most of the existing catheters use single materials or simple composite materials, which are difficult to simultaneously meet the comprehensive requirements of flexibility, anti-kinking ability, and anti-collapse ability. This single or simple material combination limits the performance of the catheter in a complex vascular environment. Moreover, although some improvement measures have improved the catheter performance, the processes are complex and the costs are high, which is not conducive to large-scale production and clinical application, making these improvement measures difficult to be widely promoted in the actual medical environment and limiting their application scope and popularity.

[0005] Chinese Patent Application Publication No. CN118490306A discloses a thrombus aspiration catheter and an interventional medical device, including a catheter body, a thrombus aspiration channel, and a drug delivery channel. The thrombus aspiration channel extends from the distal end to the proximal end, and the drug delivery channel extends from the proximal end to the distal end, respectively provided with a suction port, a drug outlet, a suction outlet, and a drug inlet. Although this technology realizes the dual functions of thrombus aspiration and drug delivery, it does not solve the problems of insufficient coating adhesion and poor surface hydrophilicity, resulting in limited performance of the catheter in a complex vascular environment, which may affect the aspiration effect and blood compatibility.

[0006] Chinese Patent Application Publication No. CN117731363A discloses an embolism dredging device and a thrombus aspiration catheter, including a catheter, a Y-shaped hemostatic valve, and an embolism dredging device. The embolism dredging device includes a dredging element, a support element, and a limit locking element, which can crush and soften the thrombus blocked in the catheter without withdrawing the catheter for flushing. Although this technology solves the problem of thrombus blockage in the catheter, it does not involve the improvement of the flexibility, anti-kinking ability, and anti-collapse ability of the catheter, and does not optimize the coating performance. Therefore, the overall performance in a complex vascular environment still needs to be improved. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention proposes an improved intracranial thrombus aspiration catheter and its preparation method, aiming to solve the problems of insufficient coating adhesion, poor surface hydrophilicity, insufficient flexibility and anti-kinking ability, and insufficient anti-collapse ability existing in the prior art.

[0008] In order to achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0009] An intracranial thrombus aspiration catheter includes a multi-layer structure from the inside to the outside:

[0010] (a) PTFE liner: located in the innermost layer of the catheter, made of polytetrafluoroethylene (PTFE) material, used to reduce thrombus adhesion and provide a smooth lumen;

[0011] (b) Coil: located outside the PTFE liner, made of stainless steel or nitinol wire winding, providing anti-collapse ability;

[0012] (c) Braiding: woven into a mesh structure by stainless steel wires, partially covering the outside of the coil, used to enhance anti-kinking ability;

[0013] (d) Plastic layer: designed in sections, with high-hardness polyurethane at the proximal end and gradually changing to low-hardness polyurethane at the distal end, achieving a hardness gradient through co-extrusion or segmented injection molding process;

[0014] (e) Radiopaque ring: made of platinum-iridium alloy, embedded in the catheter;

[0015] (f)Coating: Located on the outermost layer of a part of the catheter, and is composed of at least one of glycerol polyacrylate, polyurethane or polyethylene glycol as the base material.

[0016] Furthermore, a method for preparing an intracranial thrombus aspiration catheter is as follows:

[0017] Step 1: Prepare a PTFE inner liner using an extruder to obtain the PTFE inner liner;

[0018] Step 2: Wind nitinol wire on the outer surface of the PTFE inner liner to obtain a coil;

[0019] Step 3: Weave stainless steel wires into a mesh using a braiding machine, partially cover the coil and heat it to obtain a braid;

[0020] Step 4: Coat polyurethane on the proximal high-hardness section, switch to soft polyurethane in the distal low-hardness section, and achieve a continuous decrease in hardness through a gradual transition zone to obtain a plastic layer;

[0021] Step 5: Embed a platinum-iridium alloy imaging ring in the middle section of the catheter and fix it using pulsed laser spot welding;

[0022] Step 6: Dissolve glycerol polyacrylate in acetone, add vinyltrimethoxysilane, stir and filter to obtain an inner layer solution; add a base material and a glycidyl ether compound to acetone, add a crosslinking agent and a photoinitiator, stir and filter to obtain a surface layer solution; coat the inner layer solution on the surface of a part of the catheter and dry it, then coat the surface layer solution and perform ultraviolet curing to obtain the intracranial thrombus aspiration catheter.

[0023] Preferably, the method for preparing the intracranial thrombus aspiration catheter is as follows:

[0024] Step 1: PTFE inner liner: Prepare a PTFE inner liner using an extruder, with an extrusion temperature of 380 - 400 °C and an inner diameter controlled to be 0.05 - 0.1 mm, to obtain the PTFE inner liner;

[0025] Step 2: Coil: Wind nitinol wire on the outer surface of the PTFE inner liner using a spring winding machine, with the diameter of the nitinol wire being 0.05 - 0.1 mm, the helical pitch being 0.3 - 0.5 mm, the winding speed being 200 - 300 rpm, and the tension controlled at 5 - 10 N;

[0026] Step 3: Braid: Use a 16-axis braiding machine to braid stainless steel wires with a diameter of 0.02 - 0.04 mm into a mesh at a density of 60 - 80 PPI, partially cover the coil layer, with a braiding angle of 30 - 45°, and heat at 280 - 300 °C for 5 - 15 seconds;

[0027] Step 4, Plastic layer: At the proximal high-hardness section, a polyurethane with a Shore D of 60 - 70 is coated using a twin-screw extruder, and the extrusion temperature is 200 - 220 °C; at the distal low-hardness section, it is switched to a soft polyurethane with a Shore A of 80 - 90, and the hardness is continuously reduced through a 5 - 10 cm gradual transition zone;

[0028] Step 5, Radiopaque ring: At a position 4 - 6 cm from the head end in the middle section of the catheter, a platinum-iridium alloy radiopaque ring is embedded and fixed by pulsed laser spot welding. The wavelength of the pulsed laser is 1000 - 1100 nm, and the power is 10 - 30 W to avoid thermal damage to the plastic layer;

[0029] Step 6, Coating: Dissolve 4 - 7 parts by weight of glycerol polyacrylate in 30 - 50 parts by weight of acetone, stir at room temperature for 20 - 40 minutes, then add 1.5 - 2 parts by weight of vinyltrimethoxysilane and continue stirring for 0.5 - 2 hours. Subsequently, filter through a 0.1 - 0.3 μm pore filter to obtain the inner layer solution; then, add 10 - 20 parts by weight of a base material and 2 - 4 parts by weight of a glycidyl ether compound to 80 - 100 parts by weight of acetone, stir at 40 - 60 °C for 30 - 50 minutes until completely dissolved, then add 1 - 2 parts by weight of a crosslinking agent and 1 - 2 parts by weight of a photoinitiator and stir for 20 - 40 minutes, and filter through a 0.1 - 0.3 μm pore filter to obtain the surface layer solution; uniformly coat the inner layer solution on part of the catheter surface, place it in an oven at 50 - 70 °C to dry, then coat the surface layer solution on it and cure it with ultraviolet light to obtain an intracranial thrombus aspiration catheter.

[0030] In step 6, the base material is at least one of polyurethane and polyethylene glycol.

[0031] In step 6, the glycidyl ether compound is at least one of 1,4-butanediol diglycidyl ether and trimethylolpropane triglycidyl ether.

[0032] In step 6, the crosslinking agent is at least one of trimethylolpropane trimethacrylate and pentaerythritol tetraacrylate.

[0033] In step 6, the photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenylpropanone and 1-hydroxycyclohexyl phenyl ketone.

[0034] In step 6, the thickness of the inner layer is 3 - 5 μm, and the thickness of the surface layer is 5 - 7 μm.

[0035] In step 6, the ultraviolet light curing is carried out by curing with ultraviolet light of 300 - 350 nm for 2 - 5 minutes.

[0036] Glycerol polyacrylate, as the main component of the inner layer coating, provides good substrate adhesion and biocompatibility.

[0037] Vinyltrimethoxysilane is used as a coupling agent to enhance the bonding force between the inner layer coating and the substrate, improving the adhesion and durability of the coating.

[0038] Polyurethane or polyethylene glycol serves as the substrate for the outer layer coating. Polyurethane provides good mechanical properties and flexibility, while polyethylene glycol imparts excellent hydrophilicity and biocompatibility to the coating.

[0039] Glycidyl ether compounds react with polyurethane or polyethylene glycol to form a network structure, enhancing the stability and hydrophilicity of the coating.

[0040] The crosslinking agent further strengthens the network structure of the coating, improving the mechanical properties and durability of the coating.

[0041] The photoinitiator initiates a crosslinking reaction under ultraviolet light irradiation, promoting the curing of the coating and ensuring the rapid forming and stability of the coating.

[0042] Compared with the prior art, it has the following beneficial effects:

[0043] 1) By optimizing the coating formulation and process, the present invention significantly improves the coating adhesion of the intracranial thrombus aspiration catheter, effectively preventing the coating from peeling off and ensuring the stability and durability of the catheter during use.

[0044] 2) The intracranial thrombus aspiration catheter of the present invention has good surface hydrophilicity, greatly reducing thrombus adhesion and enhancing blood compatibility and operating performance. Brief Description of the Drawings

[0045] Figure 1 It is a structural model diagram of the intracranial thrombus aspiration catheter of the present invention;

[0046] The multi-layer structure of the intracranial thrombus aspiration catheter is as follows from the inside to the outside:

[0047] 1. PTFE liner: This is the innermost layer of the catheter, made of polytetrafluoroethylene (PTFE) material. Its function is to reduce the adhesion of thrombus to the inner wall of the catheter and provide a smooth channel for the smooth passage of thrombus during aspiration;

[0048] 2. Coil: Located outside the PTFE liner, composed of a stainless steel or nitinol wire coil. The main function of this layer is to provide anti-collapse ability and ensure that the catheter can maintain its shape and structure during use;

[0049] 3. Braiding: A mesh structure woven from stainless steel wires, partially covering the outside of the coil layer. This layer is designed to enhance the anti-kinking property of the catheter, making its navigation in the blood vessel smoother;

[0050] 4. Plastic layer: This is the outer layer of the catheter, which is designed in segments. The proximal part is made of high-hardness polyurethane material to provide sufficient support; while the distal part is made of low-hardness polyurethane to increase the flexibility of the catheter. The hardness gradient change from the proximal end to the distal end is achieved through co-extrusion or segmented injection molding processes;

[0051] 5. Radiopaque ring: The radiopaque ring made of platinum-iridium alloy is embedded in the catheter. This ring plays a role in radiography during medical imaging procedures, helping doctors to monitor the position of the catheter in real time;

[0052] 6. Coating: Located on the outermost layer of part of the catheter, its base material includes at least one of glycerol polyacrylate, polyurethane, or polyethylene glycol. The function of the coating is to further improve the surface properties of the catheter, such as hydrophilicity, biocompatibility, etc., to enhance its performance and safety during medical operations;

[0053] This multi-layer structure design aims to improve the operating performance of the intracranial thrombus aspiration catheter in complex vascular environments, while ensuring its stability and effectiveness. Detailed implementation mode

[0054] Main sources of substances:

[0055] Polyurethane with Shore D 65, origin: Germany, model: D64P477, brand: Huntsman.

[0056] Soft polyurethane with Shore A 85, origin: Germany, model: TPU A 85 P 4394, brand: Huntsman.

[0057] Glycerol polyacrylate, product number: k25, Guangdong Yuemei Chemical Co., Ltd.

[0058] Polyurethane, grade: s95A, manufacturer (origin): BASF, Germany.

[0059] Polyethylene glycol, PEG-600, brand: Lotte, Korea.

[0060] The remaining raw materials in the examples and comparative examples of the present invention are all commercially available products.

[0061] The structural model diagrams of the intracranial thrombus aspiration catheters prepared in the examples and comparative examples of the present invention are as Figure 1 shown.

[0062] Example 1

[0063] A preparation method of an intracranial thrombus aspiration catheter is as follows:

[0064] Step 1, PTFE liner: Prepare the PTFE liner using an extruder, with an extrusion temperature of 380 °C and the inner diameter controlled at 0.08 mm to obtain the PTFE liner;

[0065] Step 2, Coil: Wind a nitinol wire on the outer surface of the PTFE liner with a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the helix pitch is 0.4 mm, the winding speed is 260 rpm, and the tension control is 8 N;

[0066] Step 3, Braiding: Use a 16-axis braiding machine to braid a 0.03 mm diameter stainless steel wire into a mesh at a density of 70 PPI, partially covering the coil layer, with a braiding angle of 40°; Heat it at 300 °C for 10 seconds to fuse the braiding and the coil, ensuring no delamination;

[0067] Step 4, Plastic layer: Coating with Shore D 65 polyurethane on the proximal high-hardness section using a twin-screw extruder, with an extrusion temperature of 210 °C; Switch to soft polyurethane of Shore A 85 on the distal low-hardness section, and achieve a continuous reduction in hardness through an 8 cm gradual transition zone;

[0068] Step 5, Marking ring: Embed a platinum-iridium alloy marking ring (containing 90 wt% platinum + 10 wt% iridium) at 5 cm from the head end in the middle section of the catheter, and fix it by pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W to avoid thermal damage to the plastic layer;

[0069] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour, and then filter through a 0.2 μm pore to obtain the inner layer solution; Then, add 15 parts by weight of polyurethane and 3 parts by weight of trimethylolpropane triglycidyl ether to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, then add 1.5 parts by weight of pentaerythritol tetraacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes, and also filter through a 0.2 μm pore to obtain the surface layer solution; Uniformly coat the inner layer solution on the surface of part of the catheter, put it in an oven at 60 °C to dry, the inner layer thickness is 4 μm, then coat the surface layer solution on it, and cure it with 310 nm ultraviolet light for 3 minutes, the surface layer thickness is 6 μm, to obtain an intracranial thrombus aspiration catheter.

[0070] Example 2

[0071] A method for preparing an intracranial thrombus aspiration catheter is as follows:

[0072] Step 1, PTFE liner: Prepare a PTFE liner with an extruder, the extrusion temperature is 380 °C, and the inner diameter is controlled to be 0.08 mm to obtain the PTFE liner;

[0073] Step 2, Coil: Wind a nitinol wire on the outer surface of the PTFE liner with a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the helix pitch is 0.4 mm, the winding speed is 260 rpm, and the tension control is 8 N;

[0074] Step 3, Braiding: Use a 16-axis braiding machine to braid a 0.03 mm diameter stainless steel wire into a mesh at a density of 70 PPI, partially covering the coil layer, with a braiding angle of 40°; Heat it at 300 °C for 10 seconds to fuse the braiding and the coil, ensuring no delamination;

[0075] Step 4, Plastic layer: Use a twin-screw extruder to coat the proximal high-hardness section with polyurethane of Shore D 65, with an extrusion temperature of 210 °C; Switch to soft polyurethane of Shore A 85 in the distal low-hardness section, and achieve a continuous reduction in hardness through an 8 cm gradual transition zone;

[0076] Step 5, Radiopaque ring: Embed a platinum-iridium alloy radiopaque ring (containing 90 wt% platinum + 10 wt% iridium) at a position 5 cm from the head end in the middle section of the catheter, and fix it by pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W, avoiding thermal damage to the plastic layer;

[0077] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour, and then filter through a 0.2 μm pore size to obtain the inner layer solution; Then, add 15 parts by weight of polyurethane and 3 parts by weight of 1,4-butanediol diglycidyl ether to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, then add 1.5 parts by weight of pentaerythritol tetraacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes, and also filter through a 0.2 μm pore size to obtain the surface layer solution; Uniformly coat the inner layer solution on part of the catheter surface, put it in an oven at 60 °C to dry, the inner layer thickness is 4 μm, then coat the surface layer solution on it, and cure it with 310 nm ultraviolet light for 3 minutes, the surface layer thickness is 6 μm, to obtain an intracranial thrombus aspiration catheter.

[0078] Example 3

[0079] A preparation method of an intracranial thrombus aspiration catheter is as follows:

[0080] Step 1, PTFE liner: Prepare a PTFE liner with an extruder, with an extrusion temperature of 380 °C and an inner diameter controlled to be 0.08 mm to obtain the PTFE liner;

[0081] Step 2, Coil: Wind a nitinol wire on the outer surface of the PTFE liner with a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the helix pitch is 0.4 mm, the winding speed is 260 rpm, and the tension control is 8 N;

[0082] Step 3, Weaving: Using a 16-axis braiding machine, stainless steel wires with a diameter of 0.03 mm are braided into a mesh at a density of 70 PPI, partially covering the coil layer, with a braiding angle of 40°; heat at 300 °C for 10 seconds to fuse the braiding with the coil and ensure no delamination;

[0083] Step 4, Plastic layer: At the proximal high-hardness section, use a twin-screw extruder to coat polyurethane with Shore D 65, with an extrusion temperature of 210 °C; at the distal low-hardness section, switch to soft polyurethane with Shore A 85, and achieve a continuous reduction in hardness through an 8-cm gradual transition zone;

[0084] Step 5, Radiopaque ring: Embed a platinum-iridium alloy radiopaque ring (containing 90 wt% platinum + 10 wt% iridium) at a position 5 cm from the head end in the middle section of the catheter, and fix it using pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W to avoid thermal damage to the plastic layer;

[0085] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour. Subsequently, filter through a 0.2-μm pore filter to obtain the inner layer solution; then, add 15 parts by weight of polyurethane and 3 parts by weight of trimethylolpropane triglycidyl ether to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, then add 1.5 parts by weight of trimethylolpropane trimethacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes. Similarly, filter through a 0.2-μm pore filter to obtain the surface layer solution; uniformly coat the inner layer solution on part of the catheter surface, place it in an oven at 60 °C to dry, with the inner layer thickness of 4 μm, then coat the surface layer solution on it, and cure it with 310-nm ultraviolet light for 3 minutes, with the surface layer thickness of 6 μm, to obtain an intracranial thrombus aspiration catheter.

[0086] Example 4

[0087] A method for preparing an intracranial thrombus aspiration catheter is as follows:

[0088] Step 1, PTFE liner: Prepare a PTFE liner using an extruder, with an extrusion temperature of 380 °C and an inner diameter controlled to be 0.08 mm to obtain the PTFE liner;

[0089] Step 2, Coil: Wind nitinol wires on the outer surface of the PTFE liner using a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the spiral pitch is 0.4 mm, the winding speed is 260 rpm, and the tension is controlled at 8 N;

[0090] Step 3, Weaving: Using a 16-axis weaving machine, stainless steel wires with a diameter of 0.03 mm are woven into a mesh at a density of 70 PPI, partially covering the coil layer, with a weaving angle of 40°; heat at 300 °C for 10 seconds to fuse the weaving with the coil and ensure no delamination;

[0091] Step 4, Plastic layer: At the proximal high-hardness section, a twin-screw extruder is used to coat polyurethane with Shore D 65, and the extrusion temperature is 210 °C; at the distal low-hardness section, it is switched to soft polyurethane with Shore A 85, and the hardness is continuously reduced through an 8-cm gradual transition zone;

[0092] Step 5, Marking ring: At a position 5 cm from the head end in the middle section of the catheter, a platinum-iridium alloy marking ring (containing 90 wt% platinum + 10 wt% iridium) is embedded and fixed by pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W to avoid thermal damage to the plastic layer;

[0093] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour, and then filter through a 0.2-μm pore to obtain the inner layer solution; then, add 15 parts by weight of polyethylene glycol and 3 parts by weight of trimethylolpropane triglycidyl ether to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, then add 1.5 parts by weight of pentaerythritol tetraacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes, and also filter through a 0.2-μm pore to obtain the surface layer solution; uniformly coat the inner layer solution on the surface of part of the catheter, place it in an oven at 60 °C to dry, the inner layer thickness is 4 μm, then coat the surface layer solution on it, and cure it with 310-nm ultraviolet light for 3 minutes, the surface layer thickness is 6 μm, to obtain an intracranial thrombus aspiration catheter.

[0094] Comparative Example 1

[0095] A preparation method of an intracranial thrombus aspiration catheter is as follows:

[0096] Step 1, PTFE liner: Prepare a PTFE liner using an extruder, with an extrusion temperature of 380 °C and the inner diameter controlled to be 0.08 mm to obtain the PTFE liner;

[0097] Step 2, Coil: Wind nitinol wires on the outer surface of the PTFE liner using a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the spiral pitch is 0.4 mm, the winding speed is 260 rpm, and the tension is controlled at 8 N;

[0098] Step 3, Weaving: Using a 16-axis weaving machine, stainless steel wires with a diameter of 0.03 mm are woven into a mesh at a density of 70 PPI, partially covering the coil layer, with a weaving angle of 40°; heat at 300 °C for 10 seconds to fuse the weaving with the coil and ensure no delamination;

[0099] Step 4, Plastic layer: At the proximal high-hardness section, a twin-screw extruder is used to coat polyurethane with Shore D 65, and the extrusion temperature is 210 °C; at the distal low-hardness section, it is switched to soft polyurethane with Shore A 85, and the hardness is continuously reduced through an 8-cm gradual transition zone;

[0100] Step 5, Radiopaque ring: Embed a platinum-iridium alloy radiopaque ring (containing 90 wt% platinum + 10 wt% iridium) at 5 cm from the head end in the middle section of the catheter, and fix it by pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W to avoid thermal damage to the plastic layer;

[0101] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour. Subsequently, filter through a 0.2-μm pore filter to obtain the inner layer solution; then, add 15 parts by weight of polyurethane and 3 parts by weight of 1,3-propylene glycol cyclic sulfate to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, and then add 1.5 parts by weight of pentaerythritol tetraacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes. Similarly, filter through a 0.2-μm pore filter to obtain the surface layer solution; uniformly coat the inner layer solution on the surface of part of the catheter, place it in an oven at 60 °C to dry, the inner layer thickness is 4 μm, then coat the surface layer solution on it, and cure it with 310-nm ultraviolet light for 3 minutes, the surface layer thickness is 6 μm, to obtain an intracranial thrombus aspiration catheter.

[0102] Comparative Example 2

[0103] A method for preparing an intracranial thrombus aspiration catheter is as follows:

[0104] Step 1, PTFE liner: Prepare a PTFE liner using an extruder, with an extrusion temperature of 380 °C and an inner diameter controlled to be 0.08 mm to obtain the PTFE liner;

[0105] Step 2, Coil: Wind nitinol wires on the outer surface of the PTFE liner using a spring winding machine. The diameter of the nitinol wire is 0.06 mm, the helix pitch is 0.4 mm, the winding speed is 260 rpm, and the tension is controlled at 8 N;

[0106] Step 3, Weaving: Using a 16-axis braiding machine, braid stainless steel wires with a diameter of 0.03 mm into a mesh at a density of 70 PPI, partially covering the coil layer, with a braiding angle of 40°; heat at 300 °C for 10 seconds to fuse the braiding with the coil and ensure no delamination;

[0107] Step 4, Plastic layer: At the proximal high-hardness section, use a twin-screw extruder to coat polyurethane with Shore D 65, with an extrusion temperature of 210 °C; at the distal low-hardness section, switch to soft polyurethane with Shore A 85, and achieve a continuous reduction in hardness through an 8-cm gradual transition zone;

[0108] Step 5, Radiopaque ring: Embed a platinum-iridium alloy radiopaque ring (containing 90 wt% platinum + 10 wt% iridium) at a position 5 cm from the head end in the middle section of the catheter, and fix it using pulsed laser spot welding. The wavelength of the pulsed laser is 1064 nm, and the power is 20 W to avoid thermal damage to the plastic layer;

[0109] Step 6, Coating: Dissolve 6 parts by weight of glycerol polyacrylate in 40 parts by weight of acetone, stir at room temperature for 30 minutes, then add 1.8 parts by weight of vinyltrimethoxysilane and continue stirring for 1 hour. Subsequently, filter through a 0.2-μm pore filter to obtain the inner layer solution; then, add 15 parts by weight of polyurethane and 3 parts by weight of trimethylolpropane triglycidyl ether to 90 parts by weight of acetone, stir at 50 °C for 40 minutes until completely dissolved, then add 1.5 parts by weight of glycerol triacrylate and 1.5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropanone and stir for 30 minutes. Similarly, filter through a 0.2-μm pore filter to obtain the surface layer solution; uniformly coat the inner layer solution on the surface of part of the catheter, place it in an oven at 60 °C to dry, with the inner layer thickness of 4 μm. Then, coat the surface layer solution on it and cure it with 310-nm ultraviolet light for 3 minutes, with the surface layer thickness of 6 μm to obtain an intracranial thrombus aspiration catheter.

[0110] Test Example 1

[0111] Adhesion performance test:

[0112] Use the cross-cut method to test the adhesion, and the specific operation is as follows:

[0113] For the intracranial thrombus aspiration catheters prepared in each example and comparative example, use a cross-cut knife to draw a 6×6 cross grid with a spacing of 1 mm on the surface of the coating. Smoothly attach a 3M tape to the drawn grid surface to ensure that the tape completely covers the grid area. Then, quickly tear off the tape and observe the situation of the coating peeling off from the substrate. Grade and evaluate according to the number of grids where the coating peels off. The grades are 0, 1, 2, 3, 4, and 5 in sequence, where grade 0 represents no coating peeling off, and grade 5 indicates a large amount of coating peeling off. The test results are shown in Table 1.

[0114] Table 1

[0115]

[0116] As can be seen from the data of Test Example 1, the intracranial thrombus aspiration catheter prepared in Example 1 has good adhesion, and the detachment grade is only 0. This advantage may lie in the use of a combination of polyurethane and trimethylolpropane triglycidyl ether in its surface solution. Polyurethane has excellent mechanical properties and flexibility, and can form a strong adhesion with the substrate, while trimethylolpropane triglycidyl ether can further enhance the network structure and adhesion of the coating. In contrast, although Example 2 also uses a similar material system, the material selection is different, resulting in slightly worse adhesion. In Comparative Examples 1 and 2, 1,3-propylene glycol cyclic sulfate and glycerol triacrylate are used respectively, and the adhesion enhancement effect of these substances is relatively weak, resulting in poor coating adhesion.

[0117] Test Example 2

[0118] Contact angle test:

[0119] Using a micro syringe, 2 μL of water droplets were dropped on the surface of the intracranial thrombus aspiration catheter prepared in each example and comparative example. At the moment when the liquid droplet contacted the catheter surface, the side image of the liquid droplet was immediately captured by a video optical contact angle tensiometer (LAUDA Scientific Company, model LSA100). Subsequently, with the help of contact angle measurement software, the droplet profile was analyzed, and then the contact angle value was calculated. The size of the contact angle is inversely proportional to the surface hydrophilicity, that is, the smaller the contact angle, the stronger the surface hydrophilicity. The relevant test data are shown in Table 2.

[0120] Table 2

[0121]

[0122] The hydrophilicity of the intracranial thrombus aspiration catheter prepared in Example 4 of Test Example 2 is stronger, and the contact angle is only 18°. The possible reason lies in the polyethylene glycol used in its surface solution. Polyethylene glycol is a highly hydrophilic polymer, and its molecular chain contains a large number of hydrophilic groups, which can form hydrogen bonds with water molecules, thus significantly enhancing the hydrophilicity of the surface. Moreover, the molecular structure of polyethylene glycol is relatively uniform, which can form a stable hydrophilic coating. In addition, trimethylolpropane triglycidyl ether can form a stable network structure, further enhancing the hydrophilic performance of the coating. The pentaerythritol tetraacrylate molecule contains four acrylate groups, and these groups are more numerous and evenly distributed, which can form more hydrogen bonds with water molecules, thus significantly enhancing the hydrophilicity. In contrast, the number of polar groups of trimethylolpropane trimethacrylate and glycerol triacrylate is less and their distribution is not uniform enough, resulting in relatively weak hydrophilicity. Although the polyurethane used in other examples and comparative examples has good adhesion, its hydrophilicity is relatively weak. The hydrophilicity of 1,3-propylene glycol cyclic sulfate and glycerol triacrylate used in Comparative Examples 1 and 2 is not good, resulting in a large contact angle. Therefore, Example 4 achieved excellent hydrophilic performance by optimizing the material combination, which is of great significance for the blood compatibility and operating performance of the intracranial thrombus aspiration catheter in clinical applications.

Claims

1. A preparation method of an intracranial thrombus aspiration catheter, characterized in that The method is as follows: Step 1, PTFE liner: Prepare the PTFE liner using an extruder, with an extrusion temperature of 380 - 400 °C and an inner diameter controlled to be 0.05 - 0.1 mm to obtain the PTFE liner; Step 2, coil: Wind a nitinol wire on the outer surface of the PTFE liner using a spring winding machine. The diameter of the nitinol wire is 0.05 - 0.1 mm, the helix pitch is 0.3 - 0.5 mm, the winding speed is 200 - 300 rpm, and the tension is controlled at 5 - 10 N; Step 3, braiding: Use a 16 - axis braiding machine to braid stainless steel wires with a diameter of 0.02 - 0.04 mm into a mesh at a density of 60 - 80 PPI, partially covering the coil layer. The braiding angle is 30 - 45°, and it is heated at 280 - 300 °C for 5 - 15 seconds; Step 4, plastic layer: At the proximal high - hardness section, use a twin - screw extruder to coat polyurethane with Shore D 60 - 70, with an extrusion temperature of 200 - 220 °C; at the distal low - hardness section, switch to soft polyurethane with Shore A 80 - 90, and the hardness is continuously reduced through a 5 - 10 cm gradual transition zone; Step 5, radiopaque ring: Embed a platinum - iridium alloy radiopaque ring at a position 4 - 6 cm from the head end in the middle section of the catheter, and fix it using pulsed laser spot welding. The wavelength of the pulsed laser is 1000 - 1100 nm, and the power is 10 - 30 W to avoid thermal damage to the plastic layer; Step 6, coating: Dissolve 4 - 7 parts by weight of glycerol polyacrylate in 30 - 50 parts by weight of acetone, stir at room temperature for 20 - 40 minutes, then add 1.5 - 2 parts by weight of vinyltrimethoxysilane and continue stirring for 0.5 - 2 hours. Subsequently, filter through a 0.1 - 0.3 μm pore filter to obtain the inner layer solution; then, add 10 - 20 parts by weight of a base material and 2 - 4 parts by weight of a glycidyl ether compound to 80 - 100 parts by weight of acetone, stir at 40 - 60 °C for 30 - 50 minutes until completely dissolved, then add 1 - 2 parts by weight of a cross - linker and 1 - 2 parts by weight of a photo - initiator and stir for 20 - 40 minutes, and filter through a 0.1 - 0.3 μm pore filter to obtain the surface layer solution; uniformly coat the inner layer solution on part of the catheter surface, place it in an oven at 50 - 70 °C to dry, then coat the surface layer solution on it and cure it with ultraviolet light to obtain an intracranial thrombus aspiration catheter.

2. The method according to claim 1, wherein In step 6, the base material is at least one of polyurethane and polyethylene glycol.

3. The method according to claim 1, characterized in that In step 6, the glycidyl ether compound is at least one of 1,4 - butanediol diglycidyl ether and trimethylolpropane triglycidyl ether.

4. The method according to claim 1, wherein In step 6, the cross - linker is at least one of trimethylolpropane trimethacrylate and pentaerythritol tetraacrylate.

5. The method according to claim 1, wherein In step 6, the photo - initiator is at least one of 2 - hydroxy - 2 - methyl - 1 - phenylpropanone and 1 - hydroxycyclohexyl phenyl ketone.

6. The method according to claim 1, wherein In step 6, the thickness of the inner layer is 3 - 5 μm, and the thickness of the surface layer is 5 - 7 μm.

7. The method according to claim 1, characterized in that, In step 6, the ultraviolet light curing is to cure with ultraviolet light of 300 - 350 nm for 2 - 5 minutes.

8. An intracranial thrombus aspiration catheter, characterized in that, Prepared by the preparation method according to any one of claims 1 - 7.

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