Coated structure biliary tract stent made of soft silica gel and hard plastic and manufacturing method of coated structure biliary tract stent

Abstract

The invention discloses a coating structure biliary stent made of soft silica gel and hard plastic, which comprises an anti-corrosion inner layer, a hard plastic inner core and a coating type biocompatible outer layer, and the anti-corrosion inner layer is tubular; the hard plastic inner core comprises a plurality of mechanical supporting structure rings, the mechanical supporting structure rings are sequentially and fixedly arranged on the outer side face of the anti-corrosion inner layer in a sleeving mode at intervals in the axial direction of the biliary tract stent in a sleeving mode, the wrapping type biocompatibility outer layer comprises a plurality of wrapping type silica gel pieces, and the outer surface of each mechanical supporting structure ring is wrapped with one wrapping type silica gel piece. And each coated silica gel piece is integrally formed on the anti-corrosion inner layer. The biliary tract stent can provide mechanical properties and biocompatibility matched with a native biliary tract, can reduce stimulation to biliary tract mucosa, bear bile corrosion and reduce bacterial adhesion, can be used for a long time and can be bent and twisted to meet the normal physiological activity requirement of a human body.

Description

Technical Field

[0001] The present invention relates to the technical field of medical implants, and in particular to a biliary stent with a coating structure composed of soft silicone and hard plastic. Background Art

[0002] Biliary stricture covers the lumen constriction in parts such as bile ducts and hilar bile ducts. Many factors such as biliary stones, chronic biliary inflammation, complications after cholecystectomy or liver transplantation, primary and secondary sclerosing cholangitis, chronic pancreatitis, gallbladder cancer, ampullary malignant tumors, and metastatic cancer invading or compressing the biliary tract can cause biliary stricture, seriously affecting the health and quality of life of patients.

[0003] The biliary tract undertakes key functions such as transporting bile in the human digestive system, and its patency is crucial for maintaining normal physiological activities. Once stenosis occurs, bile excretion is blocked, leading to a series of serious complications such as jaundice and infection, and ultimately resulting in liver function decompensation, bile duct sclerosis, pain, and suppurative cholangitis.

[0004] The implantation of biliary stents has the following advantages compared with traditional catheter drainage and balloon dilation treatment methods: definite curative effect, lasting and stable effect, conforming to the biliary physiological and anatomical structure, being able to effectively achieve biliary decompression, being applicable to various biliary strictures, having few complications, small trauma, and being able to relieve the pain of patients.

[0005] Up to now, there are various types of clinically commonly used biliary stents: high-molecular plastic stents have a low price, but poor biocompatibility, are prone to bacterial adhesion and biliary tract inflammation, have a small diameter, a high blockage rate, and need to be replaced regularly; metal stents have strong radial support, do not migrate, and have a long patency duration, but have a large difference in tissue modulus from the original biliary tract, cause irritation to the biliary mucosa leading to mucosal hyperplasia, poor biocompatibility, and are easily corroded by bile; biodegradable stents have good biocompatibility and can be degraded, but have poor mechanical properties, weak radial support for the stenotic biliary tract, and the stent fragments generated during the degradation process are prone to migrate and induce cholangitis.

[0006] Therefore, the most ideal solution to solve the above problems is to design a biliary stent that can balance mechanical properties, biocompatibility, antibacterial property, corrosion resistance, and long service life, and at the same time has certain bending and torsional properties to adapt to the normal physiological activities of the human body. Summary of the Invention

[0007] To solve the above problems existing in the prior art, the present invention provides a biliary stent with a coating structure composed of soft silicone and hard plastic, which provides sufficient radial support while avoiding problems such as mucosal irritation, corrosion, blockage, and bacterial adhesion after stent implantation, and does not affect the normal physiological activities of the human body.

[0008] The technical solution adopted by the present invention is:

[0009] The present invention includes an anti-corrosion inner layer, a hard plastic inner core, and a coated biocompatible outer layer. The anti-corrosion inner layer is tubular; the hard plastic inner core is fixedly sleeved on the outer side surface of the anti-corrosion inner layer, and the coated biocompatible outer layer is coated on the outer surface of the hard plastic inner core, and the coated biocompatible outer layer is integrally formed on the anti-corrosion inner layer.

[0010] The hard plastic inner core includes a plurality of mechanical support structure rings, and each mechanical support structure ring is fixedly sleeved on the outer side surface of the anti-corrosion inner layer at intervals in the axial direction of the biliary stent. The coated biocompatible outer layer includes a plurality of coated silicone parts, and the outer surface of each mechanical support structure ring is coated with a coated silicone part, and each coated silicone part is integrally formed on the anti-corrosion inner layer.

[0011] Each coated silicone part in the anti-corrosion inner layer and the coated biocompatible outer layer is made of a medical silicone rubber material with a Shore A hardness of less than 30°, an elongation rate in the range of 500%-1500%, and a modulus of elasticity of less than 1 Mpa.

[0012] Each mechanical support structure ring in the hard plastic inner core is made of a medical-grade plastic material with a Shore A hardness greater than or equal to 80°.

[0013] The inner diameter of the tube of the anti-corrosion inner layer is 1-80 mm, and the wall thickness of the anti-corrosion inner layer is 0.1-2 mm; the wall thickness of each mechanical support structure ring in the hard plastic inner core is 0.1-3 mm; the wall thickness of each coated silicone part in the coated biocompatible outer layer is 0.1-2 mm.

[0014] A manufacturing method of a biliary stent with a coated structure composed of soft silicone and hard plastic includes the following steps:

[0015] S1. Add the medical silicone rubber material to the inkjet direct writing nozzle of the dual-nozzle four-axis printing platform, heat the rotating shaft to a constant temperature, cool the inkjet direct writing nozzle by water cooling, and then the inkjet direct writing nozzle prints the medical silicone rubber material on the outer circumferential surface of the rotating shaft by inkjet direct writing four-axis printing to form a tubular anti-corrosion inner layer;

[0016] S2. Add the medical-grade plastic material to the fused deposition nozzle of the dual-nozzle four-axis printing platform, stop heating the rotating shaft, and then the fused deposition nozzle prints the medical-grade plastic material on the outer circumferential surface of the anti-corrosion inner layer by fused deposition four-axis printing to form a plurality of mechanical support structure rings evenly spaced along the tube length direction of the biliary stent, and each mechanical support structure ring together constitutes the hard plastic inner core;

[0017] S3. When the anti-corrosion inner layer has not reached the gel point, perform the following operations:

[0018] Heat the rotating shaft to a constant temperature, and then the inkjet printer head prints the medical silicone rubber material on the outer surface of the hard plastic inner core in a four-axis inkjet printing manner to form a number of coated silicone parts covering the outer surface of the mechanical support structure ring. Each coated silicone part covers the outer surface of a mechanical support structure ring, and the coated silicone parts together constitute a coated biocompatible outer layer;

[0019] After printing is completed, cool the rotating shaft to room temperature, and then remove the final biliary stent from the rotating shaft to finally obtain a biliary stent with a coated structure composed of soft silicone and hard plastic.

[0020] In step S2, the medical-grade plastic material is specifically a medical-grade plastic wire made from medical-grade plastic particles.

[0021] In step S1, heating the rotating shaft to a constant temperature means heating it to a constant temperature of 40°C - 80°C;

[0022] In step S3, heating the rotating shaft to a constant temperature means heating it to a constant temperature of 30°C - 100°C.

[0023] The beneficial effects of the present invention are:

[0024] A biliary stent with a coated structure composed of soft silicone and hard plastic according to the present invention. The anti-corrosion inner layer structure forms a soft silicone-hard plastic hinge-like structure between the equally spaced hard plastic inner cores, providing the stent with bendable and foldable properties and serving as the most crucial part for the extension characteristics of the biliary stent to fit the stretching and displacement of the bile duct during body position changes and abdominal muscle contraction and relaxation in daily activities of the human body, meeting the normal physiological activity requirements of the human body. At the same time, the anti-corrosion inner layer is made of silicone, which is not easily adhered to or decomposed by bacteria and has good antibacterial properties; silicone has stable properties and is not corroded by bile. The middle layer of hard plastic inner cores uses materials with high hardness and flexible characteristics to provide good radial support performance for the stent and ensure the patency of the bile duct. The coated biocompatible outer layer structure is made of silicone, providing good biocompatibility and compliance for the stent. The seamless connection with the anti-corrosion inner layer realizes the coating of the hard plastic inner cores, taking into account both the biocompatibility and radial support performance of the stent. Description of the Drawings

[0025] Attached Figure 1 is a schematic structural diagram of the biliary stent with a coated structure composed of soft silicone and hard plastic according to the present invention;

[0026] Attached Figure 2 is a cross-sectional view of the biliary stent with a coated structure composed of soft silicone and hard plastic according to the present invention and the rotating shaft;

[0027] Attached Figure 3are the radial sectional view, axial sectional view, radial view, and axial view of the biliary stent with a coating structure composed of soft silicone and hard plastic according to the present invention;

[0028] Appendix Figure 4 are the radial sectional view, axial sectional view, radial view, and axial view of the biliary stent in which the anti-corrosion inner layer and the coated biocompatible outer layer of the present invention fail to connect before reaching the gel point;

[0029] Appendix Figure 5 is a schematic diagram of the dual-nozzle four-axis printing platform of the present invention;

[0030] Appendix Figure 6 is a graph showing the relationship between the elastic modulus, viscous modulus, and phase angle of the two-component silicone used in the present invention and the curing time;

[0031] In the figure: 1. Anti-corrosion inner layer, 2. Hard plastic inner core, 3. Coated biocompatible outer layer, 4. Rotating shaft, 5. High-temperature power cord, 6. Thermocouple wire, 7. Wire material, 8. Wire feeder, 9. Heating copper block nozzle, 10. Water-cooled radiator, 11. Water-cooled digital display, 12. Medical silicone rubber material, 13. Silicone mixing tube, 14. Shut-off tube, 15. Water-cooled copper block nozzle and dispensing needle tip. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] A biliary stent with a coating structure composed of soft silicone and hard plastic is as Figure 1 shown. It includes an anti-corrosion inner layer 1, a hard plastic inner core 2, and a coated biocompatible outer layer 3. The anti-corrosion inner layer 1 is tubular; the hard plastic inner core 2 is fixedly sleeved on the outer surface of the anti-corrosion inner layer 1 except for the top and bottom surfaces by hot melt deposition at equal intervals. The coated biocompatible outer layer 3 completely covers the outer surface of the hard plastic inner core 2 including the top and bottom surfaces, and the coated biocompatible outer layer 3 is cured and integrally formed together with the anti-corrosion inner layer 1.

[0034] As Figure 2 and Figure 3 shown, the hard plastic inner core 2 includes several mechanical support structure rings made of hard plastic. The hard plastic inner core 2 is annular. Each hard plastic inner core 2 is fixedly sleeved on the outer side surface of the anti-corrosion inner layer 1 at equal intervals along the axial direction of the biliary stent. The central axes of each hard plastic inner core 2 and the biliary stent are coaxially arranged. The coated biocompatible outer layer 3 includes several coated silicone parts. The outer surface of each hard plastic inner core 2 is covered with a coated silicone part, and each coated silicone part is integrally formed on the anti-corrosion inner layer 1. By this coating method, the problem that it is difficult to connect silicone and plastic is solved. The biliary stent with a coating structure will combine the advantages of soft silicone and hard plastic.

[0035] Each coated silicone part in the anti-corrosion inner layer 1 and the coated biocompatible outer layer 3 is made of medical silicone rubber material 12, which has a Shore A hardness of less than 30°, an elongation rate in the range of 500%-1500%, and an elastic modulus of less than 1 Mpa. Its elastic modulus ensures a high degree of matching with the elastic modulus of the human biliary tract, thereby ensuring good compliance.

[0036] In order to ensure matching with the elastic modulus of the human biliary tract and compliance, the anti-corrosion inner layer 1 selects low-hardness silicone with good biocompatibility.

[0037] Each mechanical support structure ring inner core in the hard plastic inner core 2 is made of medical-grade plastic material, which has a Shore A hardness greater than or equal to 80° and an elongation rate meeting the condition of more than 200%, that is, medical-grade high-hardness TPU is used, which has sufficient elastic modulus and can provide radial support force similar to that of the bile duct, enabling the hard plastic inner core 2 to have both flexibility and stretchability as the framework of the stent.

[0038] The hard plastic inner core 2 with a large enough elastic modulus provides a radial support force similar to that of the bile duct, and at the same time has flexibility and stretchability as the framework, and its structure is multiple annular structures at equal distances.

[0039] The inner diameter of the anti-corrosion inner layer 1 is 1-80 mm, and the wall thickness is 0.1-2 mm; the wall thickness of each mechanical support structure ring inner core in the hard plastic inner core 2 is 0.1-3 mm; the wall thickness of each coated silicone part in the coated biocompatible outer layer 3 is 0.1-2 mm.

[0040] A manufacturing method of a bile duct stent with a coated structure composed of soft silicone and hard plastic includes the following steps:

[0041] As Figure 5 shown, the dual-nozzle four-axis printing platform is a traditional three-axis printing platform with a fused deposition and inkjet direct writing dual-nozzle added to move with the three-axis moving platform, and a small-diameter heating rotating shaft with a thermal sensor is linked as the printing platform.

[0042] S1. Add the medical silicone rubber material 12 to the inkjet direct writing nozzle of the dual-nozzle four-axis printing platform, heat the rotatable rotating shaft 4 to a constant temperature, cool the inkjet direct writing nozzle by water cooling, and then the inkjet direct writing nozzle extrudes the medical silicone rubber material 12 by air pressure or a push rod in the inkjet direct writing four-axis printing method to print a tubular anti-corrosion inner layer 1 on the outer circumferential surface of the rotating shaft 4;

[0043] The heating rotating shaft is to ensure that the two-component silicone can be smoothly directly written onto the rotating shaft 4 while not completely curing too quickly; the ink direct-writing nozzle is cooled by the water-cooled radiator 10 to ensure that the silicone will not block the dispensing needle due to the high temperature curing of the heating rotating shaft. At the same time, the air pressure input makes the shut-off tube 14 open, and the silicone is smoothly extruded from the dispensing needle 15 and directly written with ink on the rotating shaft heated to 45 °C to prepare the base silicone layer. Stop the air pressure input, close the shut-off tube, so that the ink direct writing can be started and stopped at any time.

[0044] S2. Install the medical-grade plastic material into the fused deposition nozzle of the dual-nozzle four-axis printing platform, stop heating the rotating shaft 4, and use the residual heat to slow down the curing progress of the anti-corrosion inner layer 1 at the same time. Then the fused deposition nozzle prints the medical-grade plastic material on the outer circumferential surface of the anti-corrosion inner layer 1 in a fused deposition four-axis printing manner to form several mechanical support structure rings evenly spaced along the tube length direction of the bile duct stent. The inner cores of each mechanical support structure ring together form the mechanical hard plastic inner core 2;

[0045] Specifically, when printing the TPU mechanical support structure ring, the medical TPU particles are made into filaments and loaded into the nozzle. The filaments are fed by the gear of the wire feeder. After the filament is melted at high temperature by the heating component of the nozzle, it is deposited on the base silicone layer. The fused deposition four-axis printing is to make the medical plastic particles into filaments 7 and load them into the nozzle. The filaments 7 are fed by the gear of the wire feeder 8. After the filament 7 is melted at high temperature by the heating component of the nozzle, it is deposited on the anti-corrosion inner layer 1. Since the silicone itself has viscosity and to prevent the anti-corrosion inner layer 1 from completely curing, the rotating shaft does not need to be heated in this step.

[0046] S3. As Figure 4 shown, when the anti-corrosion inner layer 1 has not reached the gel point, perform the following operations:

[0047] Heat the rotating shaft 4 to a constant temperature, and then the ink direct-writing nozzle pneumatically extrudes or extrudes with a pressure rod the medical silicone rubber material 12 in an ink direct-writing four-axis printing manner and prints it on the outer surface of the hard plastic inner core 2 to form several coated silicone parts covering the outer surface of the inner core of the mechanical support structure ring. Each coated silicone part covers the outer surface of a hard plastic inner core 2. The coated silicone parts together form the coated biocompatible outer layer 3. The coated biocompatible outer layer 3 and the anti-corrosion inner layer 1 jointly realize the combined coating of the hard plastic inner core 2;

[0048] After printing is completed, cool the rotating shaft 4 to room temperature, and then remove the final bile duct stent from the rotating shaft 4 to finally obtain a bile duct stent with a coated structure composed of soft silicone and hard plastic.

[0049] The covering structure biliary stent composed of soft silicone and hard plastic realizes the covering structure. The key to achieving the seamless connection of the anti-corrosion inner layer 1 and the covering biocompatible outer layer 3 is to control the heating time and temperature of the rotating shaft and the printing time at each stage. Different silicones are selected with different temperatures according to different structures and paths, and the anti-corrosion inner layer 1 and the covering biocompatible outer layer 3 must be fused before the gel point.

[0050] When printing the covering biocompatible outer layer 3 in S3, it is necessary to ensure that the anti-corrosion inner layer 1 has not reached the gel point to achieve the seamless connection between the two. Then, use the inkjet direct writing four-axis printing method to print on the mechanical support structure ring and connect it with the base silicone layer to jointly achieve the covering of the mechanical support structure ring. At this time, the rotating shaft can be heated to accelerate the connection between the covering biocompatible outer layer 3 and the anti-corrosion inner layer 1.

[0051] In steps S1 and S3, the medical silicone rubber material 12 is specifically the precursor and cross-linking agent, that is, component A silicone and component B silicone; in step S2, the medical-grade plastic material is specifically the medical-grade plastic wire prepared from medical-grade plastic particles.

[0052] When printing the anti-corrosion inner layer 1 and the covering biocompatible outer layer 3, use the inkjet direct writing four-axis printing method to press the lever through the action of air pressure input, so that component A and component B silicones enter the mixing tube at the same rate and are evenly mixed. The component A silicone and component B silicone are evenly mixed to obtain good printability and appropriate curing rate. The curing rate is as Figure 6 shown, and then use the inkjet direct writing four-axis printing method to print on the linked rotating shaft.

[0053] In this embodiment, the medical-grade plastic material is specifically medical polyurethane TPU material.

[0054] The mass fraction ratio of component A silicone and component B silicone in the medical silicone rubber material 12 is 1:1. When printing the base silicone layer, component A silicone and component B silicone are evenly mixed at a ratio of 1:1 to obtain good printability and appropriate curing rate. The curing rate is as Figure 6 shown; Figure 6 represents the changes of storage modulus, loss modulus, and hysteresis angle with time, Figure 6 in which G' refers to the storage modulus, G" refers to the loss modulus, t is time, and δ is the hysteresis angle.

[0055] In step S1, the rotating shaft 4 is heated to a constant temperature of 40°C - 80°C; in step S3, the rotating shaft 4 is heated to a constant temperature of 30°C - 100°C.

[0056] The above embodiments have elaborated in detail the technical solutions and beneficial effects of the present invention. It should be clear that they are only specific examples and do not constitute a limitation to the present invention. Any modification, supplementation, and equivalent replacement within the scope of the principles of the present invention fall within the scope of protection.

Claims

1. A biliary stent with a coating structure composed of soft silicone and hard plastic, characterized in that: It includes an anti-corrosion inner layer (1), a hard plastic inner core (2) and a wrapped biocompatible outer layer (3). The anti-corrosion inner layer (1) is tubular; the hard plastic inner core (2) is fixedly sleeved on the outer side of the anti-corrosion inner layer (1), and the wrapped biocompatible outer layer (3) covers the outer surface of the hard plastic inner core (2), and the wrapped biocompatible outer layer (3) is integrally formed on the anti-corrosion inner layer (1).

2. The covered structure biliary stent composed of soft silicone and hard plastic according to claim 1, characterized in that: The described hard plastic inner core (2) includes several mechanical support structure rings, and each mechanical support structure ring is fixedly sleeved on the outer side of the anti-corrosion inner layer (1) at intervals in the axial direction of the biliary stent. The wrapped biocompatible outer layer (3) includes several wrapped silicone parts, and the outer surface of each mechanical support structure ring is covered with a wrapped silicone part, and each wrapped silicone part is integrally formed on the anti-corrosion inner layer (1).

3. The covered structure biliary stent composed of soft silicone and hard plastic according to claim 2, characterized in that: Each wrapped silicone part in the anti-corrosion inner layer (1) and the wrapped biocompatible outer layer (3) is made of a medical silicone rubber material (12) with a Shore A hardness of less than 30°, an elongation rate in the range of 500%-1500%, and an elastic modulus of less than 1 Mpa.

4. The covered structure biliary stent composed of soft silicone and hard plastic according to claim 2, characterized in that: Each mechanical support structure ring in the hard plastic inner core (2) is made of a medical-grade plastic material with a Shore A hardness greater than or equal to 80°.

5. The covered structure biliary stent composed of soft silicone and hard plastic according to claim 1, characterized in that: The inner diameter of the tube of the anti-corrosion inner layer (1) is 1-80 mm, and the wall thickness of the anti-corrosion inner layer (1) is 0.1-2 mm; the wall thickness of each mechanical support structure ring in the hard plastic inner core (2) is 0.1-3 mm; the wall thickness of each wrapped silicone part in the wrapped biocompatible outer layer (3) is 0.1-2 mm.

6. The manufacturing method of a covered structure biliary stent composed of soft silicone and hard plastic according to any one of claims 1-4, characterized in that: The method includes the following steps: S1. Add the medical silicone rubber material (12) to the ink direct writing nozzle of the dual-nozzle four-axis printing platform, heat the rotating shaft (4) to a constant temperature, cool the ink direct writing nozzle by water cooling, and then the ink direct writing nozzle prints the medical silicone rubber material (12) on the outer circumferential surface of the rotating shaft (4) by ink direct writing four-axis printing to form a tubular anti-corrosion inner layer (1); S2. Add the medical-grade plastic material to the fused deposition nozzle of the dual-nozzle four-axis printing platform, stop heating the rotating shaft (4), and then the fused deposition nozzle prints the medical-grade plastic material on the outer circumferential surface of the anti-corrosion inner layer (1) by fused deposition four-axis printing to form several mechanical support structure rings evenly spaced along the tube length direction of the biliary stent, and each mechanical support structure ring together constitutes the hard plastic inner core (2); S3. When the anti-corrosion inner layer (1) has not reached the gel point, perform the following operations: Heat the rotating shaft (4) to a constant temperature, and then the ink direct writing nozzle prints the medical silicone rubber material (12) on the outer surface of the hard plastic inner core (2) by ink direct writing four-axis printing to form several wrapped silicone parts covering the outer surface of the mechanical support structure rings. Each wrapped silicone part covers the outer surface of a mechanical support structure ring, and each wrapped silicone part together constitutes the wrapped biocompatible outer layer (3); After printing is completed, cool the rotating shaft (4) to room temperature, and then remove the final biliary stent from the rotating shaft (4) to finally obtain a biliary stent with a coating structure composed of soft silicone and hard plastic.

7. The manufacturing method of a covered structure biliary stent composed of soft silicone and hard plastic according to claim 5, characterized in that: In the step S2, the medical-grade plastic material is specifically a medical-grade plastic wire prepared from medical-grade plastic particles.

8. The manufacturing method of a covered structure biliary stent composed of soft silicone and hard plastic according to claim 5, characterized in that: In the step S1, heating the rotating shaft (4) to a constant temperature means heating it to a constant temperature of 40°C - 80°C; 9. The manufacturing method of a covered structure biliary stent composed of soft silicone and hard plastic according to claim 5, characterized in that: In the step S3, heating the rotating shaft (4) to a constant temperature means heating it to a constant temperature of 30°C - 100°C.

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