A method for preparing a magnetically controlled hydrogel blood flow guiding stent, a magnetically controlled hydrogel blood flow guiding stent and an application method

Abstract

The application belongs to the technical field of micro robots, and discloses a preparation method of a magnetic hydrogel blood flow guiding stent, the magnetic hydrogel blood flow guiding stent and an application method, and comprises the following steps: a surface-modified magnetic particle is prepared based on a synthesis method of a magnetic particle; the magnetic particle is an Fe3O4 magnetic particle which is surface-modified with SiO2; a precursor solution containing acrylonitrile, acrylamide, a photoinitiator and ethoxylated trimethylolpropane triacrylate is prepared; the precursor solution is mixed with the magnetic particle, magnetization direction orientation is performed under the action of a magnetic field, and light polymerization curing is performed; the cured product is placed in pure water to perform solvent exchange, and a magnetic hydrogel blood flow guiding stent is obtained; the magnetic hydrogel blood flow guiding stent prepared by the application has temperature response shape memory characteristics and is easy to deploy; meanwhile, the magnetic hydrogel blood flow guiding stent has ultralow bending stiffness and magnetic navigation capability, is highly adaptable and has independent controllability; after implantation, the magnetic hydrogel blood flow guiding stent can effectively improve the blood flow dynamics in an aneurysm.

Description

Technical Field

[0001] This invention relates to the field of microrobot technology, and in particular to a method for preparing a magnetically controlled hydrogel blood flow guiding stent, the magnetically controlled hydrogel blood flow guiding stent, and its application method. Background Technology

[0002] Intravascular flow shunts (FDDs) treat aneurysms by altering intravascular fluid dynamics to gradually form an intravascular thrombus. They have shown exceptional therapeutic potential in structurally complex unruptured aneurysms (such as hip aneurysms, wide-necked aneurysms, and collateral bifurcation aneurysms), and boast advantages such as high occlusion rates (70%-81%), low recurrence rates (4.8%), and low retreatment rates (3.1%). Over the past two decades, they have gradually emerged as an effective and durable treatment method. Currently, commercially available FDDs typically use a metal stent body. The rigidity of metal stents is far greater than that of human vascular tissue, which may lead to vascular damage or poor stent apposition after implantation, potentially causing endoleak or thrombus dislodgement, increasing the risk of complications. Furthermore, current FDDs rely on microcatheters for delivery. While precise intravascular delivery is possible in most cases, catheter advancement is difficult when navigating extremely tortuous cerebral vessels (especially the oblique segment of the terminal internal carotid artery (ICA), making the procedure challenging.

[0003] Therefore, existing technologies still need improvement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a magnetically controlled hydrogel blood flow guiding stent, a magnetically controlled hydrogel blood flow guiding stent and an application method, in order to solve the problem of poor adaptability of existing intravascular blood flow shunt devices.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows: In a first aspect, the present invention provides a method for preparing a magnetically controlled hydrogel blood flow guiding stent, comprising: Surface-modified magnetic particles were prepared using a method based on the synthesis of magnetic particles; the magnetic particles were Fe3O4 magnetic particles with SiO2 surface modification. Prepare a precursor solution containing acrylonitrile, acrylamide, a photoinitiator, and ethoxylated trimethylolpropane triacrylate; The precursor solution is mixed with the magnetic particles, and the magnetic orientation is achieved under the action of a magnetic field, followed by photopolymerization and solidification. The solidified material was placed in pure water for solvent exchange to obtain a magnetically controlled hydrogel blood flow guiding stent.

[0006] In one implementation, the solvent of the precursor solution is dimethyl sulfoxide; The preparation of the precursor solution containing acrylonitrile and acrylamide includes: The acrylonitrile, acrylamide, ethoxylated trimethylolpropane triacrylate, and photoinitiator are mixed to obtain a mixture; in the mixture, the molar ratio of acrylamide to acrylonitrile is 1:2.5 to 1:3.0, the acrylonitrile is 300 mg, and the corresponding solution volume of acrylamide is 868 μL; the volume of ethoxylated trimethylolpropane triacrylate is 107 μL; the photoinitiator is 60 mg, and the dimethyl sulfoxide is 3055 μL; The mixture is dissolved in dimethyl sulfoxide to prepare the precursor solution.

[0007] In one implementation, the step of mixing the precursor solution with the magnetic particles, magnetizing and orienting them under the influence of a magnetic field, and then curing them through photopolymerization includes: The magnetic particles are mixed with the precursor solution and then placed in a mold. A uniform magnetic field with an intensity of 1 mT to 10 mT is applied to align the magnetic particles along a predetermined direction. Maintaining the uniform magnetic field, the material is polymerized and cured by irradiation with an ultraviolet light source, and then shaped by curling after demolding.

[0008] In one implementation, when the solidified material is placed in pure water for solvent exchange, the magnetically controlled hydrogel blood flow guiding stent maintains a preset permanent shape, and the aqueous solution is replaced every preset time period throughout the solvent exchange process until the solvent exchange is completed.

[0009] In a second aspect, the present invention provides a magnetically controlled hydrogel blood flow guiding stent prepared based on the method for preparing a magnetically controlled hydrogel blood flow guiding stent as described in the first aspect, comprising: Shape memory hydrogel matrices with temperature-responsive properties; and Surface-modified Fe3O4 magnetic particles dispersed in the matrix; The support has a cylindrical structure with a grid-like surface.

[0010] In one implementation, the magnetically controlled hydrogel blood flow guiding stent has a strength of 0.549 N·mm² at 37°C. 2 It exhibits ultra-low bending stiffness and a high radial support force of 12.68 mN / mm; the mechanical properties of the magnetically controlled hydrogel blood flow guiding stent vary with temperature.

[0011] In one implementation, the magnetically controlled hydrogel blood flow guiding stent is compressed into a temporary solid cylindrical shape at low temperature and inserted into a delivery catheter; when the target location is reached and the ambient temperature rises to body temperature, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter and returns from the temporary shape to the permanent shape of a hollow cylinder.

[0012] In a second aspect, the present invention provides a method for applying a magnetically controlled hydrogel blood flow guiding stent as described in the second aspect, comprising: Under the control of a magnetic field, the magnetically controlled hydrogel blood flow guiding stent is controlled to move in a straight tube, in a curved tube, and in both directions of flow, so as to deliver the magnetically controlled hydrogel blood flow guiding stent to the target position. By utilizing the shape memory function of the magnetically controlled hydrogel blood flow guiding stent, when it reaches the target position, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter using body temperature, restoring from a temporary shape to a permanent hollow cylinder shape, thereby achieving hemodynamic regulation at the aneurysm site.

[0013] In one implementation, the magnetically controlled hydrogel blood flow guiding stent is used to achieve anti-blood flow intravascular navigation under the guidance of a gradient magnetic field, adaptive passage through pipes of different diameters, detour through curved pipes, and magnetically controlled fine-tuning to improve the fit rate of aneurysm inlets.

[0014] In one implementation, the magnetically controlled hydrogel flow-guiding stent is used to slow the flow velocity of blood entering the sac of a saccular aneurysm and to regulate wall shear force and vascular pressure to improve hemodynamics at the aneurysm site.

[0015] The present invention, by employing the above technical solution, has the following effects: This invention achieves shape memory effect and magnetic response capability by adding surface-modified Fe3O4 magnetic particles to a temperature-responsive shape memory material. The magnetically controlled hydrogel blood flow guiding stent prepared by this invention can be compressed into a transient structure at low temperature, delivered to the target blood vessel segment through a microcatheter, and quickly recovers to the original stent shape after entering the body temperature environment. It can achieve active navigation and positioning under magnetic field control, and at the same time has extremely low bending stiffness and high radial support force. The magnetically controlled hydrogel blood flow guiding stent prepared by this invention is easy to deploy, highly adaptable and independently controllable, and suitable for vascular diversion in complex environments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the method for preparing the magnetically controlled hydrogel blood flow guiding stent in this invention.

[0018] Figure 2 This is the front view of the support mold modeled in Solidworks in this invention.

[0019] Figure 3 This is a schematic diagram of the stent fabrication process in this invention.

[0020] Figure 4 This is a schematic diagram of the tensile fixation rate test results in this invention.

[0021] Figure 5 This is a schematic diagram of the radial compression results of the support at 37°C and 10°C in this invention.

[0022] Figure 6 This is a schematic diagram showing the three-point bending results of the support at 37℃ and 10℃ in this invention.

[0023] Figure 7 This is a flowchart of the shape memory effect testing process in this invention.

[0024] Figure 8 This is a schematic diagram of the movement process of the stent in the in vitro model in this invention.

[0025] Figure 9 This is a diagram showing the shunt effect of the stent in an in vitro model in this invention.

[0026] Figure 10 This is a schematic diagram of the integrated modeling of rigid blood vessels and stents in this invention.

[0027] Figure 11 This is a hemodynamic simulation diagram of the flow velocity within an aneurysm without and with a stent in this invention.

[0028] Figure 12 This is a schematic diagram of hemodynamic simulation of intra-aneurysmal schizophrenia (WSS) with and without stent in this invention.

[0029] Figure 13 This is a schematic diagram of hemodynamic simulation of intra-aneurysm pressure with and without stent in this invention.

[0030] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] Exemplary Method (I) Intravascular flow shunts (FDDs) treat aneurysms by altering intravascular fluid dynamics to gradually form an intravascular thrombus. They have shown exceptional therapeutic potential in structurally complex unruptured aneurysms (such as hip aneurysms, wide-necked aneurysms, and collateral bifurcation aneurysms), and boast advantages such as high occlusion rates (70%-81%), low recurrence rates (4.8%), and low retreatment rates (3.1%). Over the past two decades, they have gradually emerged as an effective and durable treatment method. Currently, commercially available FDDs typically use a metal stent body. The rigidity of metal stents is far greater than that of human vascular tissue, which may lead to vascular damage or poor stent apposition after implantation, potentially causing endoleak or thrombus dislodgement, increasing the risk of complications. Furthermore, current FDDs rely on microcatheters for delivery. While precise intravascular delivery is possible in most cases, catheter advancement is difficult when navigating extremely tortuous cerebral vessels (especially the oblique segment of the terminal internal carotid artery (ICA), making the procedure challenging.

[0033] To address the above-mentioned technical problems, this invention provides a method for preparing a magnetically controlled hydrogel blood flow guiding stent, comprising: preparing surface-modified magnetic particles using a magnetic particle synthesis method; preparing a precursor solution containing acrylonitrile (AN), acrylamide (AAm), and a photoinitiator, and using dimethyl sulfoxide (DMSO) as a solvent to obtain the precursor solution; thoroughly mixing the precursor solution with the magnetic particles, aligning the particles under magnetic field assistance, and obtaining the magnetically controlled hydrogel blood flow guiding stent through photopolymerization curing and solvent exchange; the magnetically controlled hydrogel blood flow guiding stent prepared by this invention has temperature-responsive shape memory characteristics, is easy to deploy; simultaneously possesses ultra-low bending stiffness and magnetic navigation capability, is highly adaptable and independently controllable; can effectively reduce intra-aneurysmal flow velocity, and is suitable for interventional treatment of complex cerebrovascular diseases.

[0034] like Figure 1 As shown, this embodiment of the invention provides a method for fabricating a magnetically controlled hydrogel blood flow guiding stent, comprising the following steps: Step S100: Surface-modified magnetic particles are prepared based on the synthesis method of magnetic particles; the magnetic particles are Fe3O4 magnetic particles with SiO2 surface modification.

[0035] In this embodiment, a design scheme and preparation process of a body temperature-triggered magnetically controlled shape memory soft stent (MSMS) are proposed to solve the problems of existing intravascular blood flow shunt devices being difficult to deploy in complex vascular environments, having poor adaptability, and lacking independent controllability.

[0036] The method for fabricating a magnetically controlled hydrogel flow-directing stent provided in this embodiment achieves both shape memory effect and magnetic responsiveness by adding surface-modified Fe3O4 magnetic particles to a temperature-responsive shape memory material. The magnetically controlled hydrogel flow-directing stent fabricated using this method can be compressed into a transient structure at low temperatures, delivered to the target vascular segment via a microcatheter, and rapidly recovers its original stent shape upon entering the body temperature environment. It then achieves active navigation and positioning under magnetic field control, while also possessing extremely low bending stiffness and high radial support force. The magnetically controlled hydrogel flow-directing stent fabricated in this embodiment exhibits high flexibility, making it suitable for drainage scenarios involving high curvature and distal aneurysms.

[0037] The magnetically controlled hydrogel blood flow guiding scaffold prepared in this embodiment is a soft vascular scaffold with shape memory properties and magnetic response capability. This scaffold is mainly composed of temperature-responsive shape memory hydrogel combined with Fe3O4 magnetic particles, which can complete shape recovery under body temperature conditions, and achieve controllable navigation with the help of an external magnetic field.

[0038] As an example, the magnetically controlled hydrogel blood flow guiding stent includes: a temperature-responsive shape memory material and surface-modified Fe3O4 magnetic particles added to the temperature-responsive shape memory material; in the actual design process, the structural design of the magnetically controlled hydrogel blood flow guiding stent is as follows: the stent is initially in sheet form, and is rolled into a hollow cylinder by rolling it up, and this hollow cylinder is used as the permanent shape of the stent.

[0039] The Solidworks design of the magnetically controlled hydrogel blood flow guiding scaffold is shown below. Figure 2 As shown, the initial structure is a sheet-like structure, and rhomboid holes are opened on the surface of the sheet-like structure.

[0040] Specifically, in one implementation of this embodiment, step S100 includes the following steps: Step S101: Dissolve Fe3O4 nanoparticles in anhydrous ethanol, perform the first ultrasonic treatment to form a uniform dispersion, and add ultrapure water after adding ammonia dropwise. Step S102: Perform a second ultrasonic treatment by slowly adding tetraethoxysilane, and let the solution stand for several hours after the second ultrasonic treatment. Step S103: Perform a third ultrasonic treatment, wash the magnetic powder, and freeze-dry it to obtain surface-modified Fe3O4 magnetic particles.

[0041] In this embodiment, the fabrication process of the magnetically controlled hydrogel blood flow guiding stent is as follows: Figure 3 As shown, the specific synthesis steps are as follows: Based on the synthesis method of surface-modified Fe3O4 magnetic particles, 1 gram of Fe3O4 nanoparticles were dissolved in 80 mL of anhydrous ethanol and sonicated for 30 minutes to form a uniform dispersion. Then, 15 mL of ammonia water was added dropwise, followed by 100 mL of ultrapure water. Sonication was initiated, and 0.5 mL of TEOS (tetraethoxysilane) was slowly added dropwise. Sonication continued for 2 hours, followed by overnight standing. Sonication was continued for another 6 hours, and the magnetic powder was washed and lyophilized.

[0042] In this embodiment, the surface-modified Fe3O4 magnetic particles refer to Fe3O4 magnetic particles that have been treated with the above-mentioned tetraethoxysilane to obtain Fe3O4 magnetic particles with a surface-modified layer of SiO2.

[0043] like Figure 1 As shown, this embodiment of the invention provides a method for fabricating a magnetically controlled hydrogel blood flow guiding stent, comprising the following steps: Step S200: Prepare a precursor solution containing acrylonitrile, acrylamide, a photoinitiator, and ethoxylated trimethylolpropane triacrylate.

[0044] In this embodiment, after the surface-modified Fe3O4 magnetic particles are prepared by the magnetic particle synthesis method, a precursor solution needs to be prepared. The precursor solution is used to mix with the surface-modified Fe3O4 magnetic particles prepared in step S100 and polymerize and solidify them to obtain the magnetically controlled hydrogel blood flow guiding stent.

[0045] Specifically, in one implementation of this embodiment, step S200 includes the following steps: Step S201: The acrylonitrile, the acrylamide, the ethoxylated trimethylolpropane triacrylate and the photoinitiator are mixed to obtain a mixture; Step S202: Dissolve the mixture in the dimethyl sulfoxide to obtain the precursor solution.

[0046] In this embodiment, in the mixture, the molar ratio of acrylamide (AAm) to acrylonitrile (AN) in the precursor solution is 1:2.5 to 1:3.0; preferably, the molar ratio of acrylamide (AAm) to acrylonitrile (AN) is 1:2.86.

[0047] Specifically, in the mixture, the acrylonitrile is 300 mg; the corresponding molar volume of the acrylamide solution is 868 μL; the volume of the ethoxylated trimethylolpropane triacrylate is 107 μL; the photoinitiator is 60 mg; and the dimethyl sulfoxide is 3055 μL.

[0048] As an example, in this embodiment, dimethyl sulfoxide is used as the dissolving liquid in the mixture, and the preparation method of the precursor solution is as follows: A mixture of 300 mg of AN (acrylonitrile), 868 μL of AAM (acrylamide), 107 μL of crosslinking agent ETPTA (trimethylolpropane ethoxylatetriacrylate), and 60 mg of photoinitiator 2959 (a highly efficient, non-yellowing ultraviolet photoinitiator) was prepared. This mixture was then dissolved in 3055 μL of DMSO (dimethyl sulfoxide) to obtain the precursor solution.

[0049] like Figure 1 As shown, this embodiment of the invention provides a method for fabricating a magnetically controlled hydrogel blood flow guiding stent, comprising the following steps: Step S300: The precursor solution is mixed with the magnetic particles, and the magnetic orientation is achieved under the action of a magnetic field and then solidified by photopolymerization. Step S400: The solidified material is placed in pure water for solvent exchange to obtain a magnetically controlled hydrogel blood flow guiding stent.

[0050] In this embodiment, after dissolving the obtained mixture in dimethyl sulfoxide to prepare the precursor solution, the precursor solution is aligned with the magnetization direction of the surface-modified Fe3O4 magnetic particles and then polymerized and solidified to obtain the magnetically controlled hydrogel blood flow guiding stent.

[0051] Specifically, in one implementation of this embodiment, step S300 includes the following steps: Step S301: Weigh a predetermined weight of Fe3O4 magnetic particles; Step S302: After mixing the magnetic particles with the precursor solution, place them in a mold; apply a uniform magnetic field with an intensity of 1mT~10mT (preferably 3mT) to align the magnetic particles along a preset direction; wherein, the magnetic field direction of the uniform magnetic field is perpendicular to the plane of the mold and upward. Step S303: Maintain the uniform magnetic field, use ultraviolet light source for polymerization and curing, demold, shape by curling, and place in water for solvent exchange. During solvent exchange in pure water, the magnetosensitive hydrogel blood flow guiding stent maintains a preset permanent shape, and the aqueous solution is replaced at preset intervals throughout the solvent exchange process until the exchange is complete.

[0052] As an example, in this embodiment, the specific method of scaffold synthesis and shaping is as follows: Weigh 100 mg of silica surface-modified magnetic powder (i.e., the surface-modified Fe3O4 magnetic particles), mix it thoroughly with 1 mL of precursor solution, spread it in a mold, and place it in a 3 mT uniform magnetic field to align the magnetization direction, wherein the magnetization direction is perpendicular to the plane of the mold and upward.

[0053] Turn on the ultraviolet lamp (UV lamp wavelength 365 nm, light intensity 1776 mW / cm²). 2 The solution in the mold is polymerized and solidified for 15 minutes. The resulting solid gel is demolded and shaped into a cylinder, then placed in pure water for solvent exchange. During this process, the aqueous solution is changed daily until solvent exchange is complete, which takes approximately seven days; that is, while placing the solution in the pure water for solvent exchange, the aqueous solution is changed daily until solvent exchange is complete.

[0054] Furthermore, after preparing the magnetically controlled hydrogel blood flow guiding stent, the mechanical properties of the magnetically controlled hydrogel blood flow guiding stent were verified in this embodiment using the following methods: In this embodiment, the tensile fixation rate of the magnetically controlled hydrogel blood flow guiding stent was tested to reflect its shape memory capability, and the mechanical properties of the stent were reflected by three-point bending and radial compression tests.

[0055] The deformation mechanism of the magnetically controlled hydrogel blood flow guiding stent is as follows: This is due to the response of the internal dipole-dipole bond and hydrogen bond network of the magneto-controlled hydrogel blood flow guiding stent to temperature changes. At low temperatures, hydrogen bonds preferentially form within the system, while dipole-dipole bonds are strengthened, thereby stabilizing the physically cross-linked structure to store stress and fix the temporary shape. Above 37°C, AAm forms hydrogen bonds with external water molecules, the internal physical cross-linking weakens, stress is released, and the material returns to its initial shape.

[0056] The test procedure for the tensile fixation rate of the magnetically controlled hydrogel blood flow guiding stent is as follows: The material was prepared into a strip, and the original length of the strip was measured as l0. The strip was then stretched in water at 37°C, and its fully extended length was recorded as l1. It was then fixed in water at 10°C for 5 seconds, and the fixed length was recorded as l2. Afterward, the stretched strip was placed back into water at 37°C for 10 seconds to restore its original shape; l3 represents the restored length. The shape retention rate (R) of the material is then recorded. f ) and shape recovery rate (R r It can be calculated according to formulas (1) and (2).

[0057] (1); (2); The calculation results are as follows Figure 4 As shown, the average value after five iterations is used to obtain R.f =83%, R r =96%.

[0058] The mechanical properties of a stent are generally measured through in vitro tests such as radial compression and three-point bending. The supporting force of the stent can be obtained by normalizing formula (1): (3); L c Represents the compressive load, F represents the actual measured compressive force, and L... deflated This represents the length of the stent after the balloon is unloaded; in this case, it could refer to the length of the stent during testing.

[0059] In this experiment, the maximum force on the linear segment can be approximated as the supporting force of the support frame, as follows: Figure 5 The force-displacement curve obtained by radial compression is shown. According to formula (1), the support force of the bracket is 12.68 mN / mm.

[0060] The flexibility of the stent can be characterized by a three-point bending test, and the bending stiffness of the stent can be obtained by formulas (2), (3), and (4): (4); (5); (6); According to formulas (2) and (3), the force-displacement curve obtained from the three-point bending test can be transformed into a mid-span curvature-mid-span bending moment curve, as follows: Figure 6 As shown, the slope of the linear segment of the curve is the bending stiffness of the support. Figure 6 The bending stiffness of the support was found to be 0.549 N·mm. 2 Furthermore, at 10°C, the radial stiffness and flexural stiffness of the stent are both higher than those at 37°C. This change in mechanical properties is due to the rearrangement within the polymer network: the hydrophobic cyano groups drive the interaction between the chains, breaking the hydrogen bonds between AAm and water while strengthening the internal hydrogen bonds, thereby increasing the stiffness and thus giving the stent temperature-dependent mechanical properties.

[0061] Effect verification: The effects of this stent can be divided into three aspects: shape memory effect, intravascular navigation effect, and blood flow shunting effect.

[0062] In this embodiment, the shape memory effect of the stent is verified by changing the temporary shape of the stent and the stent's recovery at 37°C. Figure 7As shown, the specific procedure involves compressing the temporary shape of the stent into a solid column at 37°C, applying stress to maintain this shape, fixing it in cold water at 10°C for 10 seconds, and then restoring its shape at 37°C. Experiments have verified that the stent has good shape memory under body temperature conditions. This characteristic facilitates the compression of the stent's diameter and its insertion into the catheter for delivery into the blood vessel, and also ensures that the stent can restore its shape after release at the target location, adhering closely to the aneurysm for drainage.

[0063] The magnetic particles in the stent material endow the stent with independent movement capabilities, thus enabling navigation within the blood vessel. To verify the stent's movement performance, a custom-designed extracorporeal aneurysm glass model was created. This model features three different inner diameters (5.5mm, 4.5mm, and 6.5mm) in the straight section and an average inner diameter of 5.5mm in the curved section, with three bends at different angles (α=95.83°, β=89.05°, γ=103.82). The model was connected to a flow pulsating pump, with a flow rate set at 0.3L / min and the flow direction as follows... Figure 8 As shown, a 5.2 mm diameter stent is started from a straight tube section and moved against the current using a 600 mT magnetic field. During the movement, the direction of the magnetic field is adjusted so that the stent can smoothly navigate bends and reach the aneurysm for deployment.

[0064] Figure 8 The study demonstrates the movement of the stent in an in vitro model, and experiments verify the stent's mobility in complex vascular environments. In real-world scenarios, catheters cannot reach some distal arteries; therefore, the stent's independent mobility compensates for this limitation in catheter delivery.

[0065] To test the shunt effect of the new stent, this embodiment uses both in vitro experiments and computational simulations for verification.

[0066] 1) In the in vitro model experiment, a wide-necked aneurysm glass model was used. The aneurysm's inner diameter was 6 mm, and the neck diameter was 4 mm. The aneurysm in the model was filled with methylene blue solution. When the red rhodamine blood flowed through the model, it gradually replaced the methylene blue solution in the aneurysm, thus visualizing the shunt effect. The experiment compared the color changes within the aneurysm with and without a stent at the same time point. The results are as follows: Figure 9 As shown in the figure. The results showed that the color change within the aneurysm was significantly slower in the group with stents than in the group without stents. This result indicates that stents can reduce the flow of blood into the aneurysm, thus achieving a shunt effect.

[0067] 2) Simulation calculations were performed using the fluid dynamics simulation software Ansys Fluent 2024. Rigid aneurysm models and stented aneurysm models were created in Solidworks (e.g., Figure 10(As shown). This model consists of a spherical sac attached to the sidewall of the parent vessel. The aneurysm has an intraluminal diameter of 10 mm, a neck width of 8 mm, and an inner vessel diameter of 5 mm. The two models were imported into Ansys Fluent for calculation and comparison. The specific steps are as follows: The model was meshed using tetrahedral elements, with a maximum of 5 layers and an element size of 0.5 mm. The number of elements in the model ranged from 300,000 to 500,000, and the average orthogonal mass of the mesh was 0.78. The inlet velocity was set to 0.70 m / s. The steady-state incompressible Navier-Stokes equations were solved using the flow velocity. Based on the Reynolds number, the flow was treated as laminar. Hemodynamic parameters, including flow velocity, wall shear stress, and pressure, were compared between stented and stentless aneurysms to quantitatively evaluate computational fluid dynamics.

[0068] like Figure 11 As shown, according to Figure 11 The flow velocity comparison diagram shows that the addition of the stent reduces the inlet flow velocity, the blood flow into the aneurysm, and changes the direction of blood flow, thus playing a role in diversion.

[0069] like Figure 12 As shown, Figure 12 The WSS (wall shear stress) distribution in the data illustrates that stent implantation can prevent both excessively low WSS within the aneurysm lumen and excessively high WSS at the aneurysm neck, thereby mitigating the potential impact of excessively high or low shear stress on aneurysm progression.

[0070] like Figure 13 As shown, Figure 13 The pressure distribution in the data indicates that the stent reduced the pressure at the aneurysm site.

[0071] This embodiment presents for the first time a FDD robot with both whole-body shape memory and magnetic control. By fusing and integrating temperature-triggered shape memory hydrogel with magnetically responsive Fe3O4 particles, the FDD combines temperature-triggered shape recovery with magnetic field-controlled vascular navigation. It retains the shape memory effect of traditional FDDs while also giving it the ability to be independently controlled without a catheter, enabling active "reverse flow" movement and precise deployment of the stent, breaking through the limitations of traditional catheter delivery.

[0072] This embodiment achieves superior mechanical properties by adjusting the material ratio and optimizing the support structure, resulting in an ultra-low bending stiffness (0.549 N·mm). 2 While possessing high radial support (12.68 mN / mm), it solves the current problem of FDD being unable to balance compliance and support. This performance makes the stent release and movement in the blood vessel less damaging to the vessel, better adaptable to the complex vascular environment, and better able to adhere to and support the vessel wall.

[0073] This embodiment achieves the following technical effects through the above technical solution: This embodiment achieves both shape memory effect and magnetic response capability by adding surface-modified Fe3O4 magnetic particles to a temperature-responsive shape memory material. The magnetically controlled hydrogel blood flow guiding stent prepared in this embodiment can be compressed into a transient structure at low temperatures, delivered to the target blood vessel segment through a microcatheter, and quickly recovers to its original stent shape after entering the body temperature environment. It achieves active navigation and positioning under magnetic field control, while also possessing extremely low bending stiffness and high radial support force. The magnetically controlled hydrogel blood flow guiding stent prepared in this embodiment is easy to deploy, highly adaptable, and independently controllable, making it suitable for vascular diversion in complex environments.

[0074] Exemplary device Based on the above-described method for fabricating a magnetically controlled hydrogel blood flow guiding stent, this invention also provides a magnetically controlled hydrogel blood flow guiding stent, comprising: Shape memory hydrogel matrices with temperature-responsive properties; and Surface-modified Fe3O4 magnetic particles dispersed in the matrix; The support has a cylindrical structure with a grid-like surface.

[0075] The temperature-responsive shape memory material is molded into a temporary shape at a first temperature state, and when the ambient temperature rises to a second temperature, the temperature-responsive shape memory material recovers from the temporary shape to a permanent shape.

[0076] Furthermore, in this embodiment, based on the above preparation method and corresponding experimental results, it can be determined that the magnetically controlled hydrogel blood flow guiding stent has a strength of 0.549 N·mm² at 37°C. 2 It exhibits ultra-low bending stiffness and a high radial support force of 12.68 mN / mm; the mechanical properties of the magnetically controlled hydrogel blood flow guiding stent vary with temperature.

[0077] In the actual application scenario of this embodiment, the magnetically controlled hydrogel blood flow guiding stent is compressed into a temporary solid cylindrical shape at low temperature and inserted into the delivery catheter; when the target location is reached and the ambient temperature rises to body temperature, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter and returns to the permanent shape of a hollow cylinder from the temporary shape.

[0078] This embodiment achieves the following technical effects through the above technical solution: The magnetically controlled hydrogel blood flow guiding stent provided in this embodiment can be compressed into a transient structure at low temperature, delivered to the target blood vessel segment through a microcatheter, and quickly recovers to the original stent shape after entering the body temperature environment. It achieves active navigation and positioning under magnetic field control, and has extremely low bending stiffness and high radial support force. The magnetically controlled hydrogel blood flow guiding stent provided in this embodiment is easy to deploy, highly adaptable, and independently controllable, making it suitable for vascular diversion in complex environments.

[0079] Exemplary Method (II) Based on the above-described method for fabricating a magnetically controlled hydrogel blood flow guiding stent and the magnetically controlled hydrogel blood flow guiding stent itself, this embodiment also provides a method for applying the magnetically controlled hydrogel blood flow guiding stent, including: Under the control of a magnetic field, the magnetically controlled hydrogel blood flow guiding stent is controlled to move in a straight tube, in a curved tube, and in both directions of flow, so as to deliver the magnetically controlled hydrogel blood flow guiding stent to the target position. By utilizing the shape memory function of the magnetically controlled hydrogel blood flow guiding stent, when it reaches the target position, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter using body temperature, restoring from a temporary shape to a permanent hollow cylinder shape, thereby achieving hemodynamic regulation at the aneurysm site.

[0080] Specifically, the magnetically controlled hydrogel blood flow guiding stent is used to achieve anti-blood flow intravascular navigation under the guidance of a gradient magnetic field, adaptive passage through pipes of different diameters, turning of curved pipes, and magnetically controlled fine-tuning to improve the fit rate of aneurysm inlet.

[0081] Specifically, the magnetically controlled hydrogel blood flow guiding stent is used to slow down the flow rate of blood entering the sac of a saccular aneurysm, and to regulate wall shear force and vascular pressure to improve hemodynamics at the aneurysm site.

[0082] Because the magnetic powder in the magnetically controlled hydrogel flow-guiding stent in this embodiment enables the stent to move independently, it can navigate within the blood vessel. To verify the stent's motion effect, a custom-designed extracorporeal aneurysm glass model was created. This model has three different inner diameters (5.5mm, 4.5mm, and 6.5mm) in the straight section and an average inner diameter of 5.5mm in the curved section, with three bends at different angles (α=95.83°, β=89.05°, γ=103.82). The model was connected to a flow pulsating pump, with a flow rate set at 0.3L / min and a flow direction as shown... Figure 8 As shown, a 5.2 mm diameter stent is started from a straight tube section and moved against the current using a 600 mT magnetic field. During the movement, the direction of the magnetic field is adjusted so that the stent can smoothly navigate bends and reach the aneurysm for deployment.

[0083] Figure 8The study demonstrates the movement of the stent in an in vitro model, and experiments verify the stent's mobility in complex vascular environments. In real-world scenarios, catheters cannot reach some distal arteries; therefore, the stent's independent mobility compensates for this limitation in catheter delivery.

[0084] To test the shunt effect of the new stent, this embodiment uses both in vitro experiments and computational simulations for verification.

[0085] 1) In the in vitro model experiment, a wide-necked aneurysm glass model was used. The aneurysm's inner diameter was 6 mm, and the neck diameter was 4 mm. The aneurysm in the model was filled with methylene blue solution. When the red rhodamine blood flowed through the model, it gradually replaced the methylene blue solution in the aneurysm, thus visualizing the shunt effect. The experiment compared the color changes within the aneurysm with and without a stent at the same time point. The results are as follows: Figure 9 As shown in the figure. The results showed that the color change within the aneurysm was significantly slower in the group with stents than in the group without stents. This result indicates that stents can reduce the flow of blood into the aneurysm, thus achieving a shunt effect.

[0086] 2) Simulation calculations were performed using the fluid dynamics simulation software Ansys Fluent 2024. Rigid aneurysm models and stented aneurysm models were created in Solidworks (e.g., Figure 10 (As shown). This model consists of a spherical sac attached to the sidewall of the parent vessel. The aneurysm has an intraluminal diameter of 10 mm, a neck width of 8 mm, and an inner vessel diameter of 5 mm. The two models were imported into Ansys Fluent for calculation and comparison. The specific steps are as follows: The model was meshed using tetrahedral elements, with a maximum of 5 layers and an element size of 0.5 mm. The number of elements in the model ranged from 300,000 to 500,000, and the average orthogonal mass of the mesh was 0.78. The inlet velocity was set to 0.70 m / s. The steady-state incompressible Navier-Stokes equations were solved using the flow velocity. Based on the Reynolds number, the flow was treated as laminar. Hemodynamic parameters, including flow velocity, wall shear stress, and pressure, were compared between stented and stentless aneurysms to quantitatively evaluate computational fluid dynamics.

[0087] like Figure 11 As shown, according to Figure 11 The flow velocity comparison diagram shows that the addition of the stent reduces the inlet flow velocity, the blood flow into the aneurysm, and changes the direction of blood flow, thus playing a role in diversion.

[0088] like Figure 12 As shown, Figure 12The WSS (wall shear stress) distribution in the data illustrates that stent implantation can prevent both excessively low WSS within the aneurysm lumen and excessively high WSS at the aneurysm neck, thereby mitigating the potential impact of excessively high or low shear stress on aneurysm progression.

[0089] like Figure 13 As shown, Figure 13 The pressure distribution in the data indicates that the stent reduced the pressure at the aneurysm site.

[0090] In summary, this invention provides a method for preparing a magnetically controlled hydrogel blood flow guiding stent, the stent itself, and its application method. The method includes: preparing surface-modified magnetic particles using a magnetic particle synthesis method; preparing a precursor solution containing acrylonitrile (AN), acrylamide (AAm), and a photoinitiator, using dimethyl sulfoxide (DMSO) as a solvent; thoroughly mixing the precursor solution with the magnetic particles, aligning the particles under magnetic field assistance, and obtaining the magnetically controlled hydrogel blood flow guiding stent through photopolymerization curing and solvent exchange. The magnetically controlled hydrogel blood flow guiding stent prepared by this invention exhibits temperature-responsive shape memory characteristics, making it easy to deploy; it also possesses ultra-low bending stiffness and magnetic navigation capabilities, exhibiting strong adaptability and independent controllability; it can effectively reduce intra-aneurysmal flow velocity and is suitable for interventional treatment of complex cerebrovascular diseases.

[0091] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for fabricating a magnetically controlled hydrogel blood flow guiding stent, characterized in that, include: Surface-modified magnetic particles were prepared using a method based on the synthesis of magnetic particles; the magnetic particles were Fe3O4 magnetic particles with SiO2 surface modification. Prepare a precursor solution containing acrylonitrile, acrylamide, a photoinitiator, and ethoxylated trimethylolpropane triacrylate; The precursor solution is mixed with the magnetic particles, and the magnetic orientation is achieved under the action of a magnetic field, followed by photopolymerization and solidification. The solidified material was placed in pure water for solvent exchange to obtain a magnetically controlled hydrogel blood flow guiding stent.

2. The method for preparing a magnetically controlled hydrogel blood flow guiding stent according to claim 1, characterized in that, The solvent for the precursor solution is dimethyl sulfoxide; The preparation of the precursor solution containing acrylonitrile and acrylamide includes: The acrylonitrile, acrylamide, ethoxylated trimethylolpropane triacrylate, and photoinitiator are mixed to obtain a mixture; in the mixture, the molar ratio of acrylamide to acrylonitrile is 1:2.5 to 1:3.0, the acrylonitrile is 300 mg, and the corresponding solution volume of acrylamide is 868 μL; the volume of ethoxylated trimethylolpropane triacrylate is 107 μL; the photoinitiator is 60 mg, and the dimethyl sulfoxide is 3055 μL; The mixture is dissolved in dimethyl sulfoxide to prepare the precursor solution.

3. The method for preparing a magnetically controlled hydrogel blood flow guiding stent according to claim 1, characterized in that, The process of mixing the precursor solution with the magnetic particles, orienting them under a magnetic field, and then curing them through photopolymerization includes: The magnetic particles are mixed with the precursor solution and then placed in a mold. A uniform magnetic field with an intensity of 1 mT to 10 mT is applied to align the magnetic particles along a predetermined direction. Maintaining the uniform magnetic field, the material is polymerized and cured by irradiation with an ultraviolet light source, and then shaped by curling after demolding.

4. The method for preparing a magnetically controlled hydrogel blood flow guiding stent according to claim 3, characterized in that, When the solidified material is placed in pure water for solvent exchange, the magnetically controlled hydrogel blood flow guiding stent maintains a preset permanent shape, and the aqueous solution is replaced every preset time during the entire solvent exchange process until the solvent exchange is completed.

5. A magnetically controlled hydrogel blood flow guiding stent prepared according to the preparation method of the magnetically controlled hydrogel blood flow guiding stent according to claims 1-4, characterized in that, include: Shape memory hydrogel matrix with temperature-responsive properties; as well as Surface-modified Fe3O4 magnetic particles dispersed in the matrix; The support has a cylindrical structure with a grid-like surface.

6. The magnetically controlled hydrogel blood flow guiding stent according to claim 5, characterized in that, The magnetically controlled hydrogel blood flow guiding stent exhibits 0.549 N·mm² at 37°C. 2 It exhibits ultra-low bending stiffness and a high radial support force of 12.68 mN / mm; the mechanical properties of the magnetically controlled hydrogel blood flow guiding stent vary with temperature.

7. The magnetically controlled hydrogel blood flow guiding stent according to claim 6, characterized in that, The magnetically controlled hydrogel blood flow guiding stent is compressed into a temporary solid cylindrical shape at low temperature and inserted into the delivery catheter; when the target location is reached and the ambient temperature rises to body temperature, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter and returns to the permanent shape of a hollow cylinder from the temporary shape.

8. A method for applying the magnetically controlled hydrogel blood flow guiding stent according to claims 5-7, characterized in that, include: Under the control of a magnetic field, the magnetically controlled hydrogel blood flow guiding stent is controlled to move in a straight tube, in a curved tube, and in both directions of flow, so as to deliver the magnetically controlled hydrogel blood flow guiding stent to the target position. By utilizing the shape memory function of the magnetically controlled hydrogel blood flow guiding stent, when it reaches the target position, the magnetically controlled hydrogel blood flow guiding stent is released from the catheter using body temperature, restoring from a temporary shape to a permanent hollow cylinder shape, thereby achieving hemodynamic regulation at the aneurysm site.

9. The application method of the magnetically controlled hydrogel blood flow guiding stent according to claim 8, characterized in that, The magnetically controlled hydrogel blood flow guiding stent is used to achieve anti-blood flow intravascular navigation under the guidance of a gradient magnetic field, adaptive passage through tubes of different diameters, turning of curved tubes, and magnetically controlled fine-tuning to improve the fit rate of aneurysm inlet.

10. The method of applying the magnetically controlled hydrogel blood flow guiding stent according to claim 8 is characterized in that, The magnetically controlled hydrogel flow guiding stent is used to slow the flow velocity of blood entering the sac of a saccular aneurysm, and to regulate wall shear force and vascular pressure to improve hemodynamics at the aneurysm site.

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