A long-term implantable gel composite braided medical catheter and its forming method

Abstract

The present invention relates to a long-term implantable gel composite braided medical catheter and its molding method. The catheter comprises an inner membrane and a gel layer, arranged sequentially from the inside out, with a braided body embedded within the gel layer. Compared to existing technologies, the present invention offers the following advantages: by incorporating a PTFE inner layer, a reinforced braided layer, and a polymer gel outer layer, it achieves a perfect combination of internal lubrication, mechanical reinforcement, and external functionalization. The novel method of combining extraction, rapid cooling, and vacuum freeze-drying not only improves production efficiency but also imparts a unique microstructure to the catheter's outer layer, enhancing its drug-carrying capacity and biocompatibility.

Description

Technical Field

[0001] The present invention relates to the technical field of medical catheters, and in particular to a long-term implantable gel composite braided medical catheter and a molding method thereof. Background Art

[0002] With the development of modern medicine, long-term implantable catheters play an increasingly important role in clinical treatment, especially in the fields of cardiovascular disease, tumor chemotherapy, and chronic disease management. However, the related products currently on the market or that have been developed fail to fully meet the comprehensive performance requirements required for long-term implantable catheters: existing long-term implantable catheters often cannot have sufficient flexibility and high strength at the same time, and are prone to problems such as kinking and breaking, especially when used in complex anatomical structures; in order to achieve functions such as sustained drug release or cell adhesion and growth, the outer surface of the catheter needs to have a large specific surface area. Traditional catheters with smooth surfaces are difficult to meet this requirement, which limits their application potential in drug delivery and tissue engineering; for catheters that need to frequently deliver liquids or instruments, lubricity of the inner lumen is crucial. However, the selection of existing catheter inner layer materials is limited and cannot provide long-lasting and efficient lubrication, which increases the difficulty of operation and may cause complications.

[0003] Therefore, there is an urgent need for a new catheter design that can provide an outer layer structure with a high specific surface area while ensuring excellent mechanical properties and ensuring high lubrication of the internal channel to meet the growing clinical needs. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a long-term implantable gel composite braided medical catheter and a molding method thereof.

[0005] The above-mentioned problem of the present invention is solved by the following technical solutions:

[0006] A long-term implantable gel composite braided medical catheter comprises an inner membrane and a gel layer which are sequentially arranged from the inside to the outside, wherein a braided body is embedded in the gel layer.

[0007] The above technical solution is further configured as follows: the braided body is a mesh structure formed by weaving a metal material.

[0008] The above technical solution is further configured as follows: the gel material of the gel layer is wrapped around the outside of each metal material forming the braided body.

[0009] The present invention also provides a molding method for molding the above-mentioned long-term implantable gel composite braided medical catheter, comprising the following steps:

[0010] S1. Material preparation: Choose flexible metal material as the core shaft, PTFE as the inner membrane material, and memory alloy or polymer material, as well as polymer solution as the braid material;

[0011] S2. Pretreatment: cleaning, disinfection and surface treatment of the mandrel;

[0012] S3, inner film molding: evenly apply PTFE to the mandrel surface;

[0013] S4, braided body forming: select appropriate braiding density and braiding angle, and braid into shape through a braiding machine;

[0014] S5. Infiltration: Slowly immerse the braided semi-finished catheter into the pre-mixed polymer solution to ensure that the entire catheter surface is fully covered.

[0015] S6, gel layer formation: quickly transfer the extracted catheter into a cryogenic liquid to trigger the sol-gel transition;

[0016] S7, post-treatment of the gel layer: draining the solvent from the gel while maintaining the three-dimensional network structure of the gel layer;

[0017] S8, molding: pulling the core shaft out of the molded catheter.

[0018] The above technical solution is further configured as follows: the diameter of the core shaft ranges from 0.2 mm to 0.5 mm.

[0019] The above technical solution is further configured as follows: in step S3, PTEF is coated on the core shaft by electrostatic spraying, dipping or extrusion process.

[0020] The above technical solution is further configured as follows: in step S3, the coated mandrel is subjected to annealing treatment.

[0021] The above technical solution is further configured as follows: in steps S1 and S5, the polymer solution extract is a polymer solution extract containing polymer materials, and the solvent is a mixed solvent of chloroform and acetic acid in a ratio of 1:10-5:5.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. By introducing a PTFE inner layer, a reinforced braided layer, and a polymer gel outer layer, the present invention achieves a perfect combination of internal lubrication, mechanical reinforcement, and external functionalization of the catheter;

[0024] 2. The novel method of combining extraction-rapid cooling-vacuum freeze-drying not only improves production efficiency, but also gives the outer layer of the catheter a unique microstructure, enhancing its drug loading capacity and biocompatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural diagram of Example 1.

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of Example 1.

[0027] Figure 3 This is a flow chart of Example 2.

[0028] In the accompanying drawings, 100 is marked, inner membrane;

[0029] 200, braided body;

[0030] 300, gel layer;

[0031] 400. Mandrel. DETAILED DESCRIPTION

[0032] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0033] like Figure 1-Figure 3 As shown, the following embodiments disclose a long-term implantable gel composite braided medical catheter and a molding method thereof. Example 1

[0034] This embodiment discloses a long-term implantable gel composite braided medical catheter, which includes an inner membrane 100 and a gel layer 300 arranged sequentially from the inside to the outside, wherein a braided body 200 is embedded in the gel layer 300.

[0035] The above is the basic solution of this embodiment.

[0036] Specific reference Figure 1 and Figure 2 As shown, the center of the inner layer membrane 100 is hollowed out for inserting the core shaft 400, which is used to form a catheter. During the forming process, the inner layer membrane 100 is wrapped around the outer periphery of the core shaft 400. After the forming is completed, the core shaft 400 is withdrawn to form a hollow tubular structure.

[0037] The core shaft 400 is preferably a silver-plated copper wire or other suitable metal wire material, which is flexible and can be bent arbitrarily to ensure the flexibility of the medical catheter after molding.

[0038] The inner membrane 100 is made of PTFE. Polytetrafluoroethylene (Teflon or PTFE), commonly known as the "King of Plastics," is a polymer compound derived from tetrafluoroethylene. It exhibits excellent chemical stability, corrosion resistance, sealing properties, high lubricity and non-stick properties, electrical insulation, and excellent aging resistance. Using this material as the inner layer of the catheter ensures a low coefficient of friction within the catheter, providing excellent lubricity and chemical stability, ensuring smooth flow of blood or instruments.

[0039] In this embodiment, the braided body 200 is composed of metal wires and polymer fibers, which are woven into a mesh or spiral shape by a braiding machine, and are wrapped around the outside of the inner layer membrane 100, surrounding the entire catheter body, forming a strong and flexible middle layer to provide the overall mechanical properties of the catheter and enhance the mechanical strength and flexibility of the catheter.

[0040] Based on the above arrangement, the braided body 200 provides additional support for the inner membrane 100, making the catheter soft and not prone to twisting, and able to adapt to the complex in vivo environment.

[0041] Preferably, in this embodiment, the gel material of the gel layer 300 is wrapped around the outside of each metal material forming the braided body 200 .

[0042] Specifically, in this embodiment, the gel layer 300 is initially in a sol state. The semi-finished catheter wrapped with the braided body 200 is immersed in the sol, and the sol wrapped outside the braided body 200 is frozen and converted into gel, thereby forming a gel layer 300 with a relatively stable shape.

[0043] The large specific surface area of the gel layer 300 allows for effective drug loading and promotes cell adhesion and proliferation on its surface, making it particularly suitable for long-term implantation therapy.

[0044] Preferably, in this embodiment, the gel layer 300 is made of a polymer material with a gel network, such as PEBAX and nylon. Example 2

[0045] This embodiment discloses a molding method for molding the long-term implantable gel composite braided medical catheter described in Example 1. The specific implementation method is as follows: Figure 3 As shown, the following steps are included:

[0046] S1. Material preparation: Select a flexible metal material as the core shaft 400, PTFE as the inner membrane 100, and memory alloy or polymer material or polymer solution as the braid 200;

[0047] S2, pretreatment: cleaning, disinfecting and surface treating the mandrel 400;

[0048] S3, inner layer film forming: applying PTFE evenly to the surface of the core shaft 400;

[0049] S4, braided body forming: select appropriate braiding density and braiding angle, and braid into shape through a braiding machine;

[0050] S5. Infiltration: Slowly immerse the semi-finished catheter with the braided body 200 into the pre-prepared polymer solution to ensure that the entire catheter surface is fully covered;

[0051] S6, gel layer formation: quickly transfer the extracted catheter into a cryogenic liquid to trigger the sol-gel transition;

[0052] S7, gel layer post-processing: draining the solvent in the gel while maintaining the three-dimensional network structure of the gel layer 300;

[0053] S8, molding: pulling the core shaft 400 out of the molded catheter.

[0054] The above is the basic solution of this embodiment.

[0055] Preferably, in this embodiment, in step S1, the shell uses silver-plated copper wire or other metal wire materials with good flexibility and rigidity as the core shaft 400, and the diameter range of the core shaft 400 is between 0.2mm-0.5mm to ensure that it will not deform or break during subsequent processing.

[0056] In step S2 , the core shaft 400 is cleaned, sterilized and surface treated in order to remove impurities and improve the adhesion of subsequent coatings.

[0057] In step S1 , the selected PTFE may be in the form of powder or granules, and its purity and uniformity must be ensured.

[0058] Preferably, the coating method in step S3 can adopt electrostatic spraying, dipping or extrusion process to evenly coat PTEF on the core shaft 400. Moreover, the extrusion process, as a more commonly used coating method, can ensure the consistency of the coating thickness and obtain a more uniform inner layer film 100 finished product.

[0059] Preferably, in this embodiment, during the coating process, the extrusion temperature is controlled to be about 370°C, the speed is 1-5 meters per minute, and the extrusion pressure is kept consistent to obtain the best coating effect.

[0060] In addition, in step S3 , the coated mandrel 400 is subjected to an annealing treatment, the purpose of which is to eliminate internal stress and enhance the stability of the PTFE inner layer film 100 .

[0061] In step S1, materials such as nickel-titanium alloy wire or polymer fibers (such as PEBAX or nylon) can be selected. Nickel-titanium alloy possesses shape memory properties, providing excellent flexibility and strength; polymer fibers offer additional wear resistance and chemical stability. Therefore, the appropriate material can be selected for molding based on the desired characteristics of the medical catheter.

[0062] In step S4 , the braiding density is preferably 40-60 strands / cm, the braiding angle is preferably 90 degrees, and the filamentous braiding material is braided into a spiral or mesh structure by a braiding machine to form a braided body 200 .

[0063] The braiding machine is preferably a multi-shuttle circular braiding machine or a multi-axial braiding machine to achieve precise braiding effects.

[0064] The braiding tension is preferably 5-10 Newtons, and the braiding speed is preferably 20-50 revolutions to ensure uniformity and tightness of the braid.

[0065] As a preferred mode of the polymer solution extracting solution, in steps S1 and S5, the polymer solution extracting solution is a polymer solution extracting solution containing polymer materials, and the solvent is a mixed solvent of chloroform and acetic acid in a ratio of 1:10-5:5.

[0066] Preferably, the polymer material may be PEBAX or nylon, etc., and the concentration of the polymer material in the solvent is controlled to be between 5% and 15% according to the desired performance of the gel layer 300.

[0067] In step S5 , the extraction time is preferably 1-5 minutes, and can be adjusted according to the concentration of the polymer solution and the size of the catheter so that the polymer solution covers the entire braided body 200 .

[0068] After the braided body 200 is soaked in the polymer solution, the polymer solution needs to be quickly converted into a gel to form a gel layer 300 with a relatively fixed shape. Therefore, in this embodiment, the soaked semi-finished catheter needs to be quickly transferred to a low-temperature liquid to trigger the sol-gel transition.

[0069] Preferably, the low-temperature solution shell is made of extremely low-temperature methanol or low-temperature water, and the temperature is preferably -80°C to -20°C. Since the freezing point of water is 0°C, the freezing point of liquid water can be changed by pressurizing the liquid water, so that it can be kept in a solution state at this low temperature.

[0070] Preferably, the cooling time is preferably 1-3 minutes to ensure that the outer layer material quickly forms a stable wet gel state.

[0071] After the gel is formed, the solvent in the gel needs to be drained to ensure the purity of the gel. In this embodiment, with the help of vacuum freeze-drying equipment, the solvent in the gel is gradually drained under low temperature and low pressure environment, while maintaining the three-dimensional network structure of the gel layer 300.

[0072] Preferably, the freezing temperature is set to -50°C to -70°C, the vacuum degree is set to about 10^-3 mbar, and the drying time is set to 12-24 hours to ensure that the solvent is completely removed without destroying the gel structure.

[0073] During the freezing process, the catheter needs to be lifted up to check its appearance and physical properties to ensure that it meets the expected design requirements.

[0074] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for forming a long-term implantable gel composite braided medical catheter, characterized by: It comprises an inner layer membrane (100) and a gel layer (300) arranged in sequence from the inside to the outside, wherein a braided body (200) is embedded in the gel layer (300); The gel material of the gel layer (300) is wrapped around the outside of each metal material forming the braided body (200); The following steps are also included: S1. Material preparation: Select a flexible metal material as the core shaft (400), select PTFE as the material of the inner layer membrane (100), and select a memory alloy or polymer material, as well as a polymer solution, as the material of the braid (200); S2, pretreatment: cleaning, disinfecting and surface treating the core shaft (400); S3, inner layer film forming: applying PTFE evenly to the surface of the core shaft (400); S4, braided body forming: select appropriate braiding density and braiding angle, and braid into shape through a braiding machine; S5, infiltration: slowly immersing the semi-finished catheter with the braided body (200) into the pre-prepared polymer solution to ensure that the entire catheter surface is fully covered; S6, gel layer formation: quickly transfer the extracted catheter into a cryogenic liquid to trigger the sol-gel transition; S7, gel layer post-processing: draining the solvent in the gel while maintaining the three-dimensional network structure of the gel layer (300); S8, molding: extracting the core shaft (400) from the molded conduit.

2. The method for forming a long-term implantable gel composite braided medical catheter according to claim 1, characterized in that: The braided body (200) is a mesh structure formed by weaving a metal material.

3. The method for forming a long-term implantable gel composite braided medical catheter according to claim 1, characterized in that: The diameter of the core shaft (400) ranges from 0.2 mm to 0.5 mm.

4. The method for forming a long-term implantable gel composite braided medical catheter according to claim 1, characterized in that: In step S3, PTEF is coated onto the core shaft (400) by electrostatic spraying, dipping or extrusion.

5. The method for forming a long-term implantable gel composite braided medical catheter according to claim 1, characterized in that: In step S3, the coated mandrel (400) is annealed.

6. The method for forming a long-term implantable gel composite braided medical catheter according to claim 1, characterized in that: In steps S1 and S5, the polymer solution extract is a polymer solution extract containing polymer materials, and the solvent is a mixed solvent of chloroform and acetic acid in a ratio of 1:10-5:5.

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