A fully biodegradable hydrogel-coated coil and its preparation method

Abstract

The present invention discloses a fully degradable hydrogel-coated coil and a preparation method thereof. The fully degradable hydrogel-coated coil comprises a coil body, wherein a hydrogel drug-loading coating is coated on the surface of the coil body, an anti-unwinding wire is arranged inside the coil body, the coil body is a degradable body, and the material of the degradable body is a degradable substrate containing a developing material. The fully degradable hydrogel-coated coil and the preparation method thereof provided by the present invention have the characteristics of complete degradability, good biocompatibility, dense packing property, excellent developing performance, and safety and reliability.

Description

Technical Field

[0001] The present invention relates to a minimally invasive interventional medical device and a preparation method thereof, and particularly to a fully biodegradable hydrogel-coated coil and a preparation method thereof. Background Art

[0002] Aneurysms, gastrointestinal bleeding, tumors, hypervascular tumors, etc. are common hemorrhagic diseases of arteries. Taking aneurysms as an example, if the aneurysm ruptures, the patient's life may be endangered. In the past, the treatment of such diseases often required surgical methods, which had high risks and large traumas, especially for elderly patients. With the progress and development of medical technology, endovascular interventional treatment has become the preferred treatment option for such diseases. Among many options, coil embolization treatment stands out due to its advantages such as safety, reliability, stable implantation, and convenient delivery, and is favored by doctors and researchers.

[0003] Currently, coil embolization devices can be divided into bare metal coils and surface-modified coils according to materials and structures. The bare metal coil is the coil with the longest development history and the most commonly used clinically. Its coil body material is platinum-tungsten alloy, which has a self-metal imaging function and good biocompatibility. After being implanted into the lesion, it occludes the lesion site through the thrombus mechanism to achieve the treatment effect. The surface-modified coils are further divided into bioactive surface-coated coils, hydrogel coils, and coils with fiber tufts. The bioactive surface-coated coil refers to coating a drug coating with a thrombus-promoting effect on the surface of the bare metal coil, such as prothrombin complex, vitamin K, reptilase, and protamine sulfate, etc.; the hydrogel coil refers to having a hydrogel filament core in the coil or a hydrogel coating on the surface of the coil body. After contacting with blood, it expands, increasing the packing property of the device. At the same time, the additional expansion of the hydrogel volume increases the filling rate of the lesion, which can reduce the implantation amount of the coil, thereby reducing the economic burden of the patient and the perioperative time; the coil with fiber tufts refers to having high-molecular materials such as nylon, polypropylene, polytetrafluoroethylene, and poly(glycolide-lactide) copolymer (PGLA) embedded outside the coil body. It builds a dense network at the lesion site through the mechanical overlap of microfibers, changes the hemodynamics, and achieves the effect of rapid and stable thrombosis. Currently, the coil body materials of all coils used clinically are 100% platinum-tungsten alloy and do not have biodegradable properties. After the implant reaches the lesion, due to mechanical occlusion or thrombus mechanism, blood supply is inhibited, but the implant will remain in the body permanently. For aneurysms, the implantation of metal coils cannot shrink the aneurysm body, so it will continuously compress the nerve tissue outside the aneurysm and cannot eliminate the mass effect. The long-term implantation of metal materials may also produce metal toxicity, causing certain damage to the human body, and its long-term safety still needs to be investigated. In addition, the metal artifacts will also affect the imaging quality during the postoperative follow-up, bringing some inconvenience to clinicians.

[0004] At present, there are patent documents mentioning the use of magnesium-based alloys to prepare degradable spring coils, but the degradation rate of magnesium alloys in the body is too fast, and the lesions may have been completely degraded before the embolization treatment effect is achieved; there are also patent documents mentioning the use of poly-L-lactic acid (PLLA) suture thread to prepare degradable spring coils, but the physical strength of this coil needs to be investigated and whether it can have a good development effect is still unknown.

[0005] Therefore, in order to solve the above problems, it is of great significance to develop a medical spring coil that is degradable, biocompatible, densely packed, has good development performance, and is safe and reliable. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a fully degradable hydrogel coated spring coil and a preparation method thereof, which has degradable properties, good biocompatibility, dense filling properties, good developing properties and is safe and reliable.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a fully degradable hydrogel coated spring coil, including a spring coil body, wherein the surface of the spring coil body is coated with a hydrogel drug-loaded coating, and anti-untwisting wire is arranged inside the spring coil body. The spring coil body is a degradable coil body, and the material of the degradable coil body is a degradable substrate containing a developing material.

[0008] Furthermore, the degradable substrate is any one or more combinations of polylactic acid, poly-L-lactic acid, polyglycolic acid, polyglycolide-lactide copolymer, polyethylene glycol, polydioxanone, and polycaprolactone.

[0009] Furthermore, the developing material is any one or more combinations of barium sulfate, tungsten powder, tantalum powder, bismuth phosphate, hydroxyapatite, triiodophenol or other iodine-containing substances.

[0010] Furthermore, the wire diameter of the degradable coil body ranges from 0.02 to 0.2 mm, the diameter of the primary coil is between 0.05 and 1 mm, the diameter of the secondary spiral coil is between 0.2 and 5 mm, and the molecular weight is 10,000 to 66,000.

[0011] Furthermore, the degradable substrate is a polyglycolide-lactide copolymer, and the K value ranges between 0.12-0.18.

[0012] Further, the material of the anti-unwinding wire is any one of polypropylene, polyethylene, polyisoprene, nitinol alloy, magnesium alloy, and poly(p-dioxanone); the thickness of the hydrogel drug-loading coating is 0.01-1 mm; the hydrogel drug-loading coating is any one of polyacrylic acid gel coatings, polyacrylamide gel coatings, polycarbonate gel coatings, polyurethane gel coatings, amphiphilic block copolymer gel coatings, transparent acetate gel coatings, chitosan gel coatings, alginate gel coatings, polyethylene glycol gel coatings, polyvinyl alcohol gel coatings, and carrageenan gel coatings.

[0013] The present invention also provides a preparation method of the above-mentioned fully degradable hydrogel-coated coil for solving the above technical problems, which includes the following steps: Step S1: Directly blend, graft or deposit the degradable substrate and the imaging material, and then make fine filaments through the electrospinning technology. Then wind and entangle the fine filaments through a mandrel die, and finally put the mandrel and the fine filaments as a whole into a precision temperature-controlled heat-setting oven for heat setting; anneal at room temperature to prepare a degradable coil with imaging performance; Step S2: Place the head and tail ends of the anti-unwinding wire into the degradable coil, and connect them with the head and tail ends of the coil by welding or gluing to form a whole; Step S3: Prepare a hydrogel drug-loading solution, coat the hydrogel drug-loading solution on the surface of the coil body, dry to form a film, and form a hydrogel drug-loading coating on the surface of the coil body.

[0014] Further, in the step S1, the mandrel is a stainless steel rod with a diameter between 0.1-0.5 mm; when winding the fine filaments, the gap width between the coils is 0.0008 inches - 0.008 inches, and the winding angle is 65°-80°; the range of the heat-setting temperature is 120°C-250°C, and the heat-setting time is 5-45 minutes.

[0015] Further, the adhesive used in the step S2 is any one or more of adhesives such as polyester, polyurethane, polyamide, and α-cyanoacrylate.

[0016] Further, the step S3 includes: dissolving a certain mass of sodium alginate in physiological saline to obtain solution A; dissolving a certain mass of acrylamide-based substances in deionized water, and then sequentially adding a certain mass of calcium carbonate and a thrombus-promoting drug for uniform mixing to obtain solution B; mixing solution A and solution B, stirring and heating uniformly, and then adding an initiator for polymerization reaction to obtain solution C; the hydrogel solution can be obtained after the solution C is naturally cooled.

[0017] Furthermore, in the mixed solution C, the mass concentration of the sodium alginate is 0.1-3%; the mass concentration of the acrylamide substance is 5-40%; the mass concentration of the calcium carbonate is 2-6%; the mass concentration of the thrombogenic drug is 0.1-1.5%; the mass concentration of the initiator is 2-8%; the acrylamide substance is any one of N-isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid; the thrombogenic drug is any one or more of vitamin K, aminomethylbenzoic acid, snake venom thrombin, prothrombin complex, aminocaproic acid, thrombin and freeze-dried human fibrinogen, anloxin, phenolsulfonamide, banifen, alpha 9SD coagulation factor; the initiator is any one of ammonium persulfate, hydrogen peroxide, potassium persulfate, benzoyl peroxide, methyl ethyl ketone peroxide, and tert-butyl benzoyl peroxide; the temperature range of the heating reaction is 30-80°C, and the polymerization reaction time is 1-5h.

[0018] Furthermore, in step S3, the coating method is spraying, brushing, electrostatic coating, dipping, spin coating or cast coating; after coating, the drying temperature range is 20-230° C., the pressure range is 0.001-3 bar, and the drying time is 2-256 h.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the fully degradable hydrogel-coated spring coil provided by the present invention has high embolic density, good biocompatibility, excellent development performance and is fully degradable, thereby solving the current problems of low spring coil embolic filling rate, non-degradable metal implants and the resulting space-occupying effect, while satisfying the development function of the spring coil during the pushing process. The specific advantages are as follows:

[0020] 1. The coil of the present invention will eventually degrade completely in the human body. For aneurysms, the space-occupying effect caused by non-degradable materials can be completely eliminated, alleviating the pain of patients;

[0021] 2. The spring coil of the present invention is made of a mixture of one or more degradable materials, and the physical strength, degradation time and other properties of the spring coil can be adjusted by adjusting the components of the raw materials.

[0022] 3. The non-metallic developing substances such as barium sulfate or iodine in the spring coil of the present invention will not produce metal artifacts in the patient's body, which is convenient for doctors to observe during or after surgery.

[0023] 4. The hydrogel drug-loaded coating on the surface of the spring coil of the present invention can expand rapidly when it comes into contact with water or blood, and the final volume can reach 3-5 times that before expansion, which greatly increases the embolization density and reduces the number of coils implanted, thereby reducing the economic burden on patients and the perioperative time of doctors.

[0024] 5. The hydrogel drug-loading coating on the surface of the coil of the present invention contains a thrombus-promoting drug, which can react with blood after being implanted into the lesion area, quickly form a thrombus, and increase the embolization density and occlusion success rate.

[0025] 6. The coil with a hydrogel drug-loading coating of the present invention is not restricted within the coil body during expansion compared with the coil with a gel inner core, so it has a larger expansion volume, and the thrombus-promoting drug in the coating can also respond more quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the coil of the embodiment of the present invention;

[0027] Figure 2 is Figure 1 the cross-sectional structural diagram of;

[0028] Figure 3 is a schematic diagram of treating an aneurysm with the coil of the present invention;

[0029] Figure 4 is a schematic cross-sectional structural diagram of the coil of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be further described below with reference to the drawings and embodiments.

[0031] Figure 1 is a schematic structural diagram of the coil of the embodiment of the present invention; Figure 2 is Figure 1 the cross-sectional structural diagram of; Figure 4 is a schematic cross-sectional structural diagram of the coil of the present invention.

[0032] Please refer to Figure 1 、 Figure 2 and Figure 4 , the fully biodegradable hydrogel coating coil provided by the present invention mainly consists of a coil body 10, a hydrogel drug-loading coating 55 and an anti-unwinding wire 20, wherein the coil body 10 is a completely biodegradable coil body and has a radiopaque particle 30.

[0033] The biodegradable coil body material is a fully biodegradable medical polymer material, which can be any one or a mixture of several of polylactic acid (PLA), poly-L-lactic acid (PLLA), polyglycolic acid (PGA), polyglycolide-lactide copolymer (PGLA), polyethylene glycol (PEG), polydioxanone (PDO), polycaprolactone (PCL), etc. After directly blending, grafting or depositing a developing material in the biodegradable material, the coil can have a developing function under X-rays. The developing material can be any one or more of barium sulfate (BaSO4), tungsten powder (W), tantalum powder (Ta), bismuth phosphate (BiPO4), hydroxyapatite (HAP), triiodophenol or other iodine-containing substances, etc. Iodine-containing substances are preferred, such as iohexol, iodized oil, etc. The composite material is made into filaments by electrospinning technology, and then the filaments are wound and entangled through a mandrel mold. Finally, the mandrel and the filaments are placed as a whole in a precision temperature-controlled heat-setting oven for heat setting. The mandrel can be a stainless steel rod with a diameter between 0.05 - 1 mm, and the preferred diameter range is 0.1 - 0.5 mm; when winding the filaments, the gap width between the coils can be 0.0005 inches - 0.01 inches, and the winding angle can be 60° - 90°. The preferred gap width range is 0.0008 inches - 0.008 inches, and the preferred winding angle range is 65° - 80°; the heat-setting temperature range can be 60°C - 800°C, and the preferred temperature range is 120°C - 250°C; the heat-setting time range can be 3 - 60 minutes, and the preferred time range is 5 - 45 minutes. After completion, the equipment is taken out and annealed at room temperature to prepare a biodegradable coil with developing performance. The wire diameter of the coil ranges between 0.02 - 0.2 mm, the diameter of the first-level coil ranges between 0.05 - 1 mm, and the diameter of the second-level spiral coil ranges between 0.2 - 5 mm. By adjusting the molecular weight or components of the biodegradable material, properties such as the hardness, physical properties, and degradation period of the coil can be adjusted.

[0034] The softness or flexibility of the coil is determined by the K factor of the spring, and the K factor is proportional to the thickness of the primary wire of the spring and the tightness of the winding. The smaller the K value, the better the flexibility of the coil. By adjusting the formula or proportion of the degradable polymer material, filaments with different wire diameters and physical strengths can be spun, and thus coils with different flexibilities can be prepared. Generally, the K value of the coil ranges between 0.1 and 0.35. Generally, the K value of the coil does not exceed 0.5. If it exceeds 0.5, its flexibility may deteriorate, and it may not be suitable for the treatment of diseases such as aneurysms, and it is likely to cause rupture at the lesion site. Generally, the K value of the coil does not fall below 0.1. If it is lower than 0.1, it may be too soft and its physical strength may not be sufficient to achieve the therapeutic effect. In this solution, for example, a certain amount of PLA and PGA are copolymerized to obtain a PGLA copolymer with a K value of about 0.12 - 0.18, which has good flexibility, and then its degradation performance and mechanical properties are changed by adjusting the molecular weight.

[0035] The material of the anti-unwinding wire can be any one of polypropylene (PP), polyethylene (PE), polyisoprene (PI), nitinol, magnesium alloy, etc. The anti-unwinding wire is preferably made of poly(p-dioxanone) (PDO). The ether bond in the PDO material endows it with good flexibility and tensile strength, and it has good anti-bending fatigue performance. It can be bent multiple times at room temperature without deformation or damage. When using high molecular weight PDO as the anti-unwinding wire, the tensile force it can withstand is greater than 1N, and it is less likely to unwind during the operation. The PDO material also has good biocompatibility and biodegradability, can be naturally degraded in the body, and the PDO material is stable and will not react incompatibly with other component materials of the coil. The overall length of the anti-unwinding wire does not exceed the length of the coil, and its diameter is between 0.01 and 0.3 mm. The head and tail ends of the anti-unwinding wire are connected to the head and tail ends of the coil in a welded form or using an adhesive to form a whole. The adhesive can be any one or more of polyester, polyurethane, polyamide, α-cyanoacrylate adhesives, etc.

[0036] The material of the hydrogel drug-loading coating can be any one of polyacrylic acid gel coatings, polyacrylamide gel coatings, polycarbonate gel coatings, polyurethane gel coatings, amphiphilic block copolymer gel coatings, transparent acetate gel coatings, chitosan gel coatings, alginate gel coatings, polyethylene glycol gel coatings, polyvinyl alcohol gel coatings, carrageenan gel coatings, etc. Any raw material that can make the hydrogel have water swelling and drug-loading properties can be applicable here. The raw material of the hydrogel coating is preferably an acrylamide-based raw material because its structural unit contains an amide group, which is easy to form hydrogen bonds, thus having better water solubility and chemical activity. Dissolve a certain mass of sodium alginate in physiological saline to obtain solution A; dissolve a certain mass of acrylamide-based substance in deionized water, and then sequentially add a certain mass of calcium carbonate and thrombus-promoting drugs for uniform mixing to obtain solution B. Mix solution A and solution B, stir and heat evenly, and then add an initiator for polymerization reaction to obtain solution C. The hydrogel solution can be obtained after solution C is naturally cooled. In the overall mixed solution, the mass concentration of sodium alginate is 0.1-3%, preferably 0.1-1.5%; the mass concentration of acrylamide-based substance is 5-40%, preferably 10-30%; the mass concentration of calcium carbonate is 2-6%, preferably 3.5-5%; the mass concentration of thrombus-promoting drug is 0.1-1.5%, preferably 0.5-1%; the mass concentration of initiator is 2-8%, preferably 3-5%. The acrylamide-based substance can be any one of N-isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid. The thrombus-promoting drug can be any one or more of vitamin K, aminomethylbenzoic acid, reptilase, prothrombin complex, aminocaproic acid, thrombin and freeze-dried human fibrinogen, adrenergic, etamsylate, benyfen, alpha 9SD coagulation factor, etc. The initiator can be any one of ammonium persulfate, hydrogen peroxide, potassium persulfate, benzoyl peroxide, methyl ethyl ketone peroxide, tert-butyl benzoyl peroxide, etc. The temperature range of the heating reaction is 30-80°C, preferably 40-55°C; the polymerization reaction time is 1-5h, preferably 1.5-3h.

[0037] Place the head and tail ends of the anti-unwinding wire into the spring coil body, and connect them to the head and tail ends of the spring coil through welding process or adhesive technology to form an integral body. Specifically, the anti-unwinding wire is at the central position of the spring coil, so that the force is more uniform during the delivery stage. Then, coat the surface of the spring coil body with the hydrogel drug-loading solution. The coating method can be spraying, brushing, electrostatic coating, dip coating, spin coating or flow coating, etc., and the spraying method is preferred because the coating is more uniform and the thickness is controllable in this way. The thickness range of the coating is between 0.01 - 1 mm, preferably 0.01 - 0.5 mm, and more preferably 0.01 - 0.1 mm. After coating, dry the coating to form a film, the temperature range is 20 - 230 °C, preferably 30 - 120 °C; the pressure range is 0.001 - 3 bar, preferably 0.002 - 1 bar; the drying time is 2 - 256 h, preferably 6 - 96 h. After the film formation is completed, cool it naturally to obtain the final spring coil product. As Figure 3 shown, 15 is the aneurysm body, 25 is the spring coil, 35 is the blood vessel, and the expanded spring coil 25 almost fills the aneurysm body 15; Figure 4 in which 45 is the spring coil body and 55 is the hydrogel drug-loading coating.

[0038] Example 1

[0039] The raw material of the fully degradable hydrogel-coated coil in this embodiment is poly(p-dioxanone) (PDO) with a high molecular weight. PDO is commonly used as a medical suture in the medical field. It has good biocompatibility, can be completely degraded in the body, and the degradation period of high-molecular-weight PDO is about 6 - 12 months, avoiding the risk of premature degradation before the device reaches the embolization treatment effect. After reacting and mixing PDO with non-metallic imaging materials such as barium sulfate (BaSO4), bismuth phosphate (BiPO4), or iodine-containing substances, it can have imaging properties under X-rays and will not produce metal artifacts. The material is made into a coil through precision processes such as spinning, winding, and heat setting. An anti-unwinding wire is placed into the coil body of the coil, and its head and tail ends are connected to the head and tail ends of the coil in the form of welding or gluing. Finally, a hydrogel drug-loaded solution is coated on the surface of the coil body. The material of the anti-unwinding wire is PDO with an even higher molecular weight. The hydrogel drug-coated layer is a material based on acrylamide. A certain amount of sodium alginate is dissolved in physiological saline to obtain solution A; a certain amount of acrylamide-based substance is dissolved in deionized water, and then a certain amount of calcium carbonate and a thrombus-promoting drug are added in sequence for uniform mixing to obtain solution B. Solution A and solution B are mixed, stirred evenly and heated, and then an initiator is added for a polymerization reaction to obtain solution C. The hydrogel solution can be obtained after solution C is naturally cooled. In the overall mixed solution, the mass concentration of sodium alginate is 0.5%; the mass concentration of acrylamide-based substance is 20%; the mass concentration of calcium carbonate is 4%; the mass concentration of thrombus-promoting drug is 0.5%; the mass concentration of initiator is 4%. The acrylamide-based substance can be any one of N-isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid. The thrombus-promoting drug can be any one or more of vitamin K, aminomethylbenzoic acid, hemocoagulase, prothrombin complex, aminocaproic acid, thrombin, freeze-dried human fibrinogen, adoniside, etamsylate, banifen, alpha 9SD coagulation factor, etc. The initiator can be any one of ammonium persulfate, hydrogen peroxide, potassium persulfate, benzoyl peroxide, methyl ethyl ketone peroxide, tert-butyl benzoyl peroxide, etc. The temperature range of the heating reaction is 50°C; the polymerization reaction time is 2 h. After the hydrogel solution is prepared, it is coated on the surface of the coil body by spraying, with a thickness of 0.05 mm, a drying temperature of 70°C, a pressure of 0.5 bar, and a drying time of 24 h.

[0040] Example 2

[0041] The overall implementation process of this example is generally the same as that of Example 1, and the difference from Example 1 is the different components of the coil raw material. The raw material of this coil is a copolymer of polycaprolactone (PCL) and polylactic acid (PLA). Both PCL and PLA have certain shape memory functions and can prepare coils with better coil-forming ability; the degradation period of PCL is relatively long, and the degradation period of PLA is relatively short, and their copolymer combines their degradation times.

[0042] Although the present invention has been disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the claims.

Claims

1. A fully biodegradable hydrogel-coated coil, comprising a coil body, characterized in that, The surface of the spring coil body is coated with a hydrogel drug-loading coating. An anti-unwinding wire is arranged inside the spring coil body. The spring coil body is a degradable coil body, and the material of the degradable coil body is a degradable substrate containing a developing material; The degradable substrate is a polyglycolide-lactide copolymer with a molecular weight ranging from 10,000 to 66,000; The material of the anti-unwinding wire is any one of polypropylene, polyethylene, polyisoprene, nitinol alloy, magnesium alloy, and poly(p-dioxanone); The thickness of the hydrogel drug-loading coating is 0.01 - 1 mm; the hydrogel drug-loading coating is any one of polyacrylic acid gel coatings, polyacrylamide gel coatings, polycarbonate gel coatings, polyurethane gel coatings, amphiphilic block copolymer gel coatings, hyaluronic acid gel coatings, chitosan gel coatings, alginate gel coatings, polyethylene glycol gel coatings, polyvinyl alcohol gel coatings, and carrageenan gel coatings.

2. The fully biodegradable hydrogel-coated coil according to claim 1, wherein The developing material is any one or a combination of barium sulfate, tungsten powder, tantalum powder, bismuth phosphate, hydroxyapatite, triiodophenol, or other iodine-containing substances.

3. The fully biodegradable hydrogel-coated coil according to claim 1, characterized in that, The wire diameter range of the degradable coil body is between 0.02 - 0.2 mm, the diameter of the first-level coil is between 0.05 - 1 mm, the diameter of the second-level spiral coil is between 0.2 - 5 mm, and the K value range is between 0.12 - 0.

18.

4. A preparation method of the fully biodegradable hydrogel-coated coil according to any one of claims 1-3, characterized in that, It includes the following steps: Step S1: After directly blending, grafting, or depositing the degradable substrate and the developing material, make fine filaments through electrospinning technology, then wind and entangle the fine filaments through a mandrel die, and finally put the mandrel and the fine filaments as a whole into a precision temperature-controlled heat-setting oven for heat setting; anneal at room temperature to prepare a degradable spring coil with developing performance; Step S2: Place the head and tail ends of the anti-unwinding wire into the degradable spring coil, and connect them with the head and tail ends of the spring coil into one body through a welding process or an adhesive method; Step S3: Prepare a hydrogel drug-loading solution, coat the hydrogel drug-loading solution on the surface of the spring coil body, dry to form a film, and form a hydrogel drug-loading coating on the surface of the spring coil body.

5. The preparation method of the fully biodegradable hydrogel-coated coil according to claim 4, characterized in that, In step S1, the mandrel is a stainless steel rod with a diameter between 0.1 - 0.5 mm; when winding the fine filaments, the gap width between the coils is 0.0008 inches - 0.008 inches, and the winding angle is 65° - 80°; the heat-setting temperature range is 120°C - 250°C, and the heat-setting time is 5 - 45 minutes.

6. The preparation method of the fully biodegradable hydrogel-coated coil according to claim 4, characterized in that, The adhesives used in step S2 are any one or more of polyester, polyurethane, polyamide, and α-cyanoacrylate adhesives.

7. The preparation method of the fully biodegradable hydrogel-coated coil according to claim 4, wherein, Step S3 includes: Dissolve a certain mass of sodium alginate in physiological saline to obtain solution A; Dissolve a certain mass of acrylamide substances in deionized water, and then sequentially add a certain mass of calcium carbonate and a thrombus-promoting drug and mix evenly to obtain solution B; Mix solution A and solution B, stir and heat evenly, and then add an initiator for polymerization reaction to obtain solution C; After the solution C is naturally cooled, a hydrogel solution can be obtained.

8. The preparation method of the fully biodegradable hydrogel-coated coil according to claim 7, wherein, In the mixed solution C, the mass concentration of sodium alginate is 0.1-3%; the mass concentration of acrylamide substances is 5-40%; the mass concentration of calcium carbonate is 2-6%; the mass concentration of thrombus-promoting drugs is 0.1-1.5%; the mass concentration of initiators is 2-8%; the acrylamide substances are any one of N-isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid; the thrombus-promoting drugs are any one or more of vitamin K, aminomethylbenzoic acid, hemocoagulase, prothrombin complex, aminocaproic acid, thrombin, freeze-dried human fibrinogen, adoniside, etamsylate, benyfen, and alpha 9SD coagulation factor; the initiators are any one of ammonium persulfate, hydrogen peroxide, potassium persulfate, benzoyl peroxide, methyl ethyl ketone peroxide, and tert-butyl benzoyl peroxide; the temperature range of the heating reaction is 30-80°C, and the polymerization reaction time is 1-5 h.

9. The preparation method of the fully biodegradable hydrogel-coated coil according to claim 4, characterized in that, In the step S3, the coating method is spraying, brushing, electrostatic coating, dip coating, spin coating or flowing; after the coating is completed, the drying temperature range is 20-230°C, the pressure range is 0.001-3 bar, and the drying time is 2-256 h.

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