A multifunctional anti-stenosis drug-coated stent, its preparation method and application

Abstract

This invention discloses a multifunctional anti-stenosis drug-coated stent, comprising a nickel-titanium stent with a PLLA-TPU-based drug-loaded coating on its outer surface and a drug-loaded membrane attached to its inner surface. The multifunctional anti-stenosis drug-coated stent prepared by this invention has a nickel-titanium stent body with good biocompatibility. The outer surface of the stent is coated with a PLLA-TPU-based drug-loaded coating suspension, exhibiting good degradation performance and adjustable mechanical properties. Drug release effectively inhibits the excessive inward or outward growth of tumor cells. Simultaneously, the drug-loaded membrane in the inner layer of the nickel-titanium stent effectively inhibits tumor cells while also preventing the accumulation of biliary sludge, making it suitable for the treatment of biliary strictures. This invention also provides a method for preparing the above-mentioned multifunctional anti-stenosis drug-coated stent, which is prepared using liquid flame spraying technology and lamination, resulting in a simple preparation method and short preparation cycle.

Description

Technical Field

[0001] This invention relates to the field of functional coating technology, specifically to a multifunctional anti-stenosis drug-coated stent, its preparation method, and its application. Background Technology

[0002] Currently, hepatobiliary diseases are among the most prevalent and dangerous diseases threatening human life and health worldwide, characterized by high mortality and severe incidence. Biliary stricture, a common complication of hepatobiliary diseases, has diverse causes, including surgical trauma, inflammation, and tumor factors, and significantly impacts patients' quality of life. In recent years, advancements in endoscopic and minimally invasive techniques have driven research into early diagnosis and precision treatment, becoming a key focus in this field.

[0003] Biliary strictures are classified as benign or malignant. Bile duct cancer and pancreatic cancer are among the main causes of malignant biliary strictures. Stenotic bile ducts prevent bile from flowing from the liver and gallbladder into the duodenum, leading to digestive system abnormalities, cirrhosis, and jaundice.

[0004] Bile sludge is a mixture of cholesterol crystals, bilirubin calcium salts, proteins, and other substances precipitated from bile. The accumulation of bile sludge is accompanied by the formation of biofilms, which in turn exacerbates sludge accumulation. When bile sludge accumulates in the bile ducts for a long period, it can easily cause blockages within the ducts and may also accumulate on the surface of bile duct stents, leading to stent blockage. This blockage hinders normal bile drainage and can cause complications such as cholestasis, cholangitis, and even jaundice.

[0005] Biliary stent implantation can relieve biliary pressure and improve patency, serving as a palliative treatment for biliary strictures. Current clinical challenges include restenosis caused by biliary sludge accumulation and inward or excessive tumor growth after bare-metal stent implantation. Research on drug-eluting stents to address restenosis caused by tumor growth is urgently needed.

[0006] Plastic stents and metal stents are typical traditional biliary stents. With plastic stents, the occlusion can easily lead to the formation of bacterial biofilms. With metal stents, whether bare metal or covered, excessive inward or outward growth of the tumor can cause biofilm formation and biliary sludge accumulation, making the bile duct prone to restenosis. Therefore, modification of the stent surface is receiving increasing attention, especially research on anti-biofilm coatings and drug-eluting coatings.

[0007] The anti-biliary sludge drug-coated stent consists of four parts: a bare metal stent, a drug carrier, a drug, and a coating material. It uses the bare metal stent as the substrate for the coating material, and prepares a suspension by uniformly mixing the drug loaded by the drug carrier into the coating material for spraying and dipping coating.

[0008] There are many choices of coating polymer materials, such as polyvinyl alcohol (PVA), polycaprolactone (PCL), polylactic acid (PLA), polylactic acid-glycolic acid copolymer (PLGA), and polyglycolic acid lactide (PGA). These materials have good biocompatibility and are essentially non-toxic when degraded in vivo.

[0009] The coating polymer system consisted of poly-L-lactic acid (PLLA) and thermoplastic polyurethane (TPU). PLLA exhibits good degradation properties, while TPU offers excellent toughness and ductility. The addition of TPU not only ensures the coating's biodegradability but also provides it with elastic mechanical properties compatible with self-expanding metal scaffolds. Furthermore, both PLLA and TPU possess excellent biocompatibility and are widely used in drug delivery. The hydrophilic coating and the addition of antibacterial agents effectively prevent protein contact with the material, reducing protein adsorption and thus inhibiting biofilm formation and minimizing sludge accumulation.

[0010] Currently, research on biliary stents is quite mature with traditional non-degradable bare stents, but the disadvantages and drawbacks of bare stents are also obvious. Research on surface-modified biliary stents is receiving increasing attention, such as biodegradable biliary stents, functional coatings, tissue engineering, and 3D printed stents, including prospects for epithelialization-promoting coated stents, multifunctional coated stents, biodegradable shape memory stents, and 4D bioprinting.

[0011] Patent document CN109701092A discloses a biodegradable (P3 / 4HBPCL)PU medical biliary stent, the materials of which include: polytetrahydrofuran ether glycol (PTMG), hydroxyl-terminated polylactic acid (PLAOH), hexamethylene diisocyanate (HDI), poly(ε-caprolactone) (PCL), poly(3-hydroxybutyrate) / 4-hydroxybutyrate (P3 / 4HB), paclitaxel, lactic acid, a non-toxic catalyst, dichloromethane, a catalyst, and a chain extender. The method includes: (1) lactic acid impurity removal; (2) direct polycondensation synthesis of hydroxyl-terminated polylactic acid; (3) synthesis of biodegradable polyurethane medical elastomer; and (4) preparation of the biodegradable (P3 / 4HBPCL)PU medical biliary stent material. The biodegradable TAXOL (P3 / 4HBPCL)PU nano-biliary stent is formed by coaxial electrospinning process assisted by a special soluble mandrel. This stent has biocompatibility, safety, controlled drug release, and the effect of preventing benign biliary strictures. However, this invention mainly involves modifying and synthesizing materials and designing processes to form the scaffold, making the preparation process relatively complex.

[0012] Chinese patent document CN119524218A discloses a method for preparing a drug-coated stent, comprising: preparing a NiTi alloy shape memory stent; preparing a PMEA-based drug-loaded coating suspension slurry; and applying the prepared PMEA-based drug-loaded coating suspension slurry to the outer surface of the NiTi alloy shape memory stent using liquid flame spraying to obtain a drug-coated stent. The application of liquid flame spraying technology to stent surface modification results in a drug-coated stent with good anti-adsorption protein properties, which can be used for the treatment of hepatobiliary diseases in clinical practice.

[0013] With the rapid increase in biliary tract diseases, research on anti-biliary sludge drug-coated biliary stents is of great significance: it can improve the treatment effect of diseases such as cholangiocarcinoma, especially the control and treatment of tumor recurrence; alleviate patients' pain, prolong their survival, and improve their quality of life; promote the application of new drug-coated materials, and provide new directions for the development of stent technology. Summary of the Invention

[0014] To address the aforementioned technical problems, this invention provides a multifunctional anti-stenosis drug-coated stent, comprising a nickel-titanium stent, a PLLA-TPU-based drug-loaded coating on the outer surface of the stent, and a drug-loaded membrane on the inner surface of the stent. It can exert a dual effect of anti-tumor and anti-biliary sludge accumulation and is suitable for the treatment of biliary stricture.

[0015] A multifunctional anti-stenosis drug-coated stent includes a nickel-titanium stent, the outer surface of which is coated with a PLLA-TPU-based drug-loaded coating, and the inner surface of which is attached with a drug-loaded membrane, the drug-loaded membrane being an anti-tumor membrane, a TPU membrane, and an anti-biliary sludge membrane in sequence from the inner surface of the nickel-titanium stent.

[0016] The multifunctional anti-stenosis drug-coated stent prepared in this invention has a nickel-titanium stent body with good biocompatibility. The outer surface of the stent is coated with a PLLA-TPU-based drug-loaded coating suspension slurry, which has good degradation performance and adjustable mechanical properties. The release of the drug can effectively inhibit the excessive inward or outward growth of tumor cells. At the same time, the drug-loaded membrane of the inner layer of the nickel-titanium stent is divided into three layers, namely an anti-tumor membrane, a TPU membrane, and an anti-biliary sludge membrane, from the inner surface of the nickel-titanium stent. The anti-tumor membrane can inhibit tumor cells, while the anti-biliary sludge membrane can inhibit the formation of bacterial biofilm through antibacterial agents, thereby preventing biliary sludge accumulation and biliary restenosis. It can be used for the treatment of biliary stenosis.

[0017] Preferably, the PLLA-TPU-based drug-loaded coating is loaded with antitumor drug I, and the antitumor membrane is loaded with antitumor drug II. The antitumor drugs I and II are at least one of cisplatin, carboplatin, oxaliplatin, 5-fluorouracil, methotrexate, doxorubicin, paclitaxel, sorafenib, or gemcitabine.

[0018] In this invention, the outer surface of the nickel-titanium scaffold is coated with a PLLA-TPU-based drug-loaded coating containing antitumor drug I, which can effectively inhibit the excessive inward or outward growth of tumor cells through drug release. The inner surface is coated with an antitumor membrane loaded with antitumor drug II, which can also synergistically exert antitumor effects.

[0019] More preferably, the loading of antitumor drug I in the PLLA-TPU-based drug-loaded coating is 0.2-5%, and the loading of antitumor drug II in the antitumor membrane is 0.9-10%.

[0020] In specific embodiments of the present invention, antitumor drugs I and II are both 5-fluorouracil (5-FU). 5-FU is a pyrimidine antimetabolite whose active metabolite can inhibit thymidine synthase (TS) and block DNA synthesis; at the same time, it can also be incorporated into RNA to interfere with the normal function of RNA. This dual-attack mechanism enables it to effectively inhibit rapidly proliferating tumor cells, and it also has broad-spectrum anticancer activity. Its pharmacokinetic characteristics are suitable for local controlled release and its formulation development is mature, and it is inexpensive.

[0021] Preferably, the anti-biliary sludge membrane is loaded with an antibacterial agent, which is at least one of benzalkonium chloride, chlorhexidine, polymyxin B, vancomycin, gentamicin, erythromycin, or levofloxacin.

[0022] More preferably, the loading of antibacterial agent in the anti-sludge membrane is 0.9~10%.

[0023] In a specific embodiment of the present invention, the antibacterial agent is chlorhexidine. As a broad-spectrum antibacterial agent, chlorhexidine is widely used in medical devices, biomaterial surface modification and other fields due to its high efficiency, safety and long-lasting effect.

[0024] Preferably, the thickness of the anti-tumor membrane, TPU membrane, and anti-biliary sludge membrane is 10~30 μm.

[0025] This invention also provides a method for preparing the above-mentioned multifunctional anti-stenosis drug-coated stent, comprising the following steps:

[0026] (1) Preparation of drug-loaded membrane;

[0027] (2) Preparation of PLLA-TPU-based drug-loaded coating suspension slurry: Under the action of a catalyst, amine monomers, aldehyde monomers and antitumor drugs are placed in acetonitrile for Schiff base reaction to obtain drug-loaded COF suspension. After centrifugation, washing and drying, drug-loaded COF powder is obtained. The drug-loaded COF powder is dispersed in the oil phase and then added to a mixed solution of PLLA and TPU for ultrasonication to obtain PLLA-TPU-based drug-loaded coating suspension slurry.

[0028] (3) The PLLA-TPU-based drug-loaded coating suspension slurry obtained in step (2) is coated onto the outer surface of the nickel-titanium scaffold by liquid flame spraying to obtain a nickel-titanium scaffold loaded with PLLA-TPU-based drug-loaded coating.

[0029] (4) The drug-loaded membrane obtained in step (1) is laminated onto the inner surface of the nickel-titanium stent obtained in step (3) to obtain a multifunctional anti-stenosis drug-coated stent.

[0030] This invention utilizes liquid flame spraying technology for stent surface modification. A PLLA-TPU-based drug-loaded coating suspension is applied to the outer surface of a nickel-titanium stent using liquid flame spraying. Then, a drug-loaded membrane is laminated onto the inner surface of the nickel-titanium stent to prepare a multifunctional anti-stenosis drug-loaded stent. Compared to coatings prepared using traditional coating techniques, thermal spraying coatings offer advantages such as better coating uniformity, better coating adhesion, and simpler methods. Furthermore, the preparation method of this invention is simple and has a short preparation cycle, offering significant advantages for clinical applications.

[0031] Preferably, the method for preparing the drug-loaded membrane includes the following steps:

[0032] S1. TPU particles are prepared into TPU film using a casting machine;

[0033] S2. The mixed solution of antitumor drug II and organic substance I, and the mixed solution of antibacterial agent and organic substance II are respectively prepared into antitumor membrane and anti-biliary sludge membrane by casting machine.

[0034] More preferably, in step S1, the operating temperature of the casting machine is 180~200 ℃ and the pressure is 0.5~2 MPa.

[0035] More preferably, in step S2, the organic compound I is hydroxypropyl methylcellulose, polyethylene glycol or polyvinyl alcohol, and the organic compound II is thermoplastic polyurethane or polycaprolactone.

[0036] More preferably, in step S2, the mass ratio of antitumor drug II to organic matter I in the antitumor membrane is 1~10:100, and the mass ratio of antibacterial agent to organic matter II in the anti-biliary sludge membrane is 1~10:100.

[0037] More preferably, in step S2, the operating temperature of the casting machine is 40~80 ℃, the pressure is 0.5~2 MPa, and the time is 5~20 min.

[0038] Preferably, in step (2), the amine monomer and aldehyde monomer are dehydrated and dried before use.

[0039] In this invention, the amine monomer and aldehyde monomer need to be dehydrated and dried before use, otherwise it will affect the Schiff base reaction, reduce the yield of drug-loaded COF powder, and change the structure of drug-loaded COF powder.

[0040] Preferably, in step (2), the amine monomer is at least one of 1,3,5-tris(4-aminophenyl)benzene, p-phenylenediamine, 2,5-diaminop-benzoquinone, 1,3,5-triazine-2,4,6-triamine, 4,4'-diaminobiphenyl, 2,6-diaminopyridine, 2,5-diaminothiophene, 2,4-diaminoimidazolium, or 5,10,15,20-tetra(aminophenyl)porphyrin; and the aldehyde monomer is at least one of terephthalaldehyde, pyromellitic benzoaldehyde, 2,5-dihydroxy-1,4-benzoquinone, 1,3,5-trialdehyde-1,3,5-triazine, 1,2,4,5-tetraaldehyde-benzoquinone, 2,5-dicarboxythiophene, 2,6-dicarboxypyridine, or 9,9-dicarboxyfluorene.

[0041] In this invention, an amine monomer is used as a nucleophile. The nitrogen atom with a lone pair of electrons in the amine monomer attacks the carbonyl group with a positive charge in the aldehyde monomer, resulting in a nucleophilic addition reaction to form an intermediate α-hydroxyamine compound. Then, it is further dehydrated to form a Schiff base (i.e., COF powder), and at the same time, an antitumor drug I is loaded in situ onto the COF powder.

[0042] Preferably, in step (2), the molar ratio of the amine monomer, the aldehyde monomer and the antitumor drug I is 0.67~1:1:1~4.

[0043] Preferably, in step (2), the catalyst is acetic acid, and the volume of the acetic acid is 1% to 20% of the volume of acetonitrile.

[0044] More preferably, the catalyst is added at a rate of 0.1 to 5 mL / min.

[0045] Preferably, in step (2), the Schiff base reaction time is 1 to 24 h.

[0046] In this invention, if the reaction time is less than 1 hour, the yield is low and the crystallinity of the product is poor; if the reaction time is greater than 24 hours, the reactants are prone to agglomeration or reversible decomposition with increasing moisture content, thereby reducing the yield.

[0047] Preferably, in step (2), the centrifugation, washing and drying steps are as follows: after centrifuging the drug-loaded COF suspension to obtain drug-loaded COF colloid, detergent is added to the drug-loaded COF colloid to remove impurities, and the remaining substances are dried to obtain drug-loaded COF powder.

[0048] More preferably, the detergent is acetonitrile or ethanol, the volume ratio of the drug-loaded COF colloid to the detergent is 1:10~40, and the number of washing cycles is 5~10.

[0049] In this invention, since the residual amine monomer, aldehyde monomer and catalyst are all in the acetonitrile solution after the Schiff base reaction, it is necessary to add detergent to wash and remove impurities multiple times.

[0050] More preferably, the centrifugal speed is 8000~12000 r / min.

[0051] More preferably, the drying temperature is 80~120 ℃ and the time is 12~24 h.

[0052] Preferably, in step (2), the oil phase is at least one of petroleum ether, hexane, heptane, silicone oil, or mineral oil.

[0053] Preferably, in step (2), the mass ratio of the drug-loaded COF powder to the oil phase is 1:10~100.

[0054] Preferably, in step (2), the mass ratio of PLLA to TPU is 1~10:10.

[0055] Preferably, in step (3), the parameters of the liquid flame spraying process are: O2 as the combustion-supporting gas, pressure of 0.2~0.8 MPa, and flow rate of 1~4.0 Nm³. 3 / h; using C2H2 as fuel gas, pressure 0.05~0.3 MPa, flow rate 0.5~2 Nm³ / h. 3 / h.

[0056] Preferably, in step (3), during the liquid flame spraying process, the concentric rotation speed of the nickel-titanium support is 50~200 r / min, the spraying distance between the flame gun and the outer surface of the support is 200~500 mm, the moving speed is 300~1000 mm / s, the spraying angle is 45~135°, and the number of coating spraying passes is 5~20.

[0057] Preferably, in step (4), the lamination process is carried out at a temperature of 80~120 ℃, a pressure of 0.5~2 MPa, and a time of 5~20 min.

[0058] Preferably, in step (4), the drug-loaded membrane is subjected to corona treatment with a voltage of 10~15 kV and a treatment time of 1~2 min; the nickel-titanium scaffold needs to be sandblasted with a sand particle size of 60~120 mesh.

[0059] This invention also provides the application of the aforementioned multifunctional anti-stenosis drug-coated stent in the treatment of biliary tract diseases. The drug-coated stent of this invention exhibits good biocompatibility, good degradation performance, and adjustable mechanical properties. Drug release effectively inhibits the excessive inward or outward growth of tumor cells. Simultaneously, the drug-loaded membrane in the inner layer of the nickel-titanium stent effectively inhibits tumor cells while also preventing the accumulation of biliary sludge. It can be used clinically for the treatment of biliary tract strictures and has promising application prospects and economic benefits in the treatment of biliary tract diseases.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] (1) The multifunctional anti-stenosis drug-coated stent prepared in this invention is a nickel-titanium stent with good biocompatibility, good degradation performance, and adjustable mechanical properties. The outer surface of the nickel-titanium stent is coated with a PLLA-TPU-based drug-loaded coating containing antitumor drugs, and the inner surface of the nickel-titanium stent is attached with a three-layer drug-loaded membrane system, which can simultaneously exert the dual effects of antitumor and anti-biliary sludge accumulation. The release of the antitumor drugs in the outer layer can effectively inhibit the excessive inward or outward growth of tumor cells. At the same time, the drug-loaded membrane in the inner layer of the nickel-titanium stent can effectively inhibit tumor cells and also effectively prevent the accumulation of biliary sludge. It can be used in the clinical treatment of biliary stricture diseases and has good application prospects and economic benefits in the treatment of biliary diseases.

[0062] (2) The COF powder prepared by the present invention has high specific surface area and porosity, adjustable pore size, controllable drug release, good biocompatibility and excellent stability. It can release drugs in a pH-responsive mechanism in a weakly acidic tumor microenvironment.

[0063] (3) The present invention uses liquid flame spraying technology to coat the prepared PLLA-TPU-based drug-loaded coating suspension slurry onto a nickel-titanium scaffold to prepare a drug-loaded coating scaffold. Compared with coatings prepared by traditional coating technology, it can ensure a high coating deposition efficiency, and the coating has good coating uniformity and improves the adhesion between the coating and the substrate, which can ensure that the drug can maintain its original efficacy after spraying. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the structure of the multifunctional anti-stenosis drug-coated stent prepared in Examples 1 and 2 of this invention.

[0065] Figure 2 The infrared spectrum of the 5-FU@RT-COF powder prepared in Example 1 is shown.

[0066] Figure 3 The image shows the XRD pattern of the 5-FU@RT-COF powder prepared in Example 1.

[0067] Figure 4 This is a microscopic morphology image of the 5-FU@RT-COF powder prepared in Example 1.

[0068] Figure 5 This is a standard curve of 5-FU concentration versus absorbance.

[0069] Figure 6 This is a graph showing the toxicity test of 5-FU@RT-COF powder prepared in Example 1 against human hepatobiliary cancer cells.

[0070] Figure 7 The images show the external surface microstructures of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, where a to c are the external surface microstructures of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, respectively.

[0071] Figure 8 The images show cross-sectional SEM images of the multifunctional anti-stenosis drug-coated stent prepared in Example 1 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, where a and b are cross-sectional SEM images of the multifunctional anti-stenosis drug-coated stent prepared in Example 1 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, respectively.

[0072] Figure 9 The release curves of 5-FU of the multifunctional anti-stenosis drug-coated stent prepared in Example 2 in PBS at pH 5.5 and pH 7.4 are shown.

[0073] Figure 10 The images show the inhibitory effects of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2, the drug-free nickel-titanium coated stent prepared in Comparative Example 1, and the bare nickel-titanium stent prepared in Comparative Example 2 on human hepatobiliary cancer cells.

[0074] Figure 11 The images show scanning electron microscope (SEM) images of the multifunctional anti-stenosis drug-coated stent prepared in Example 2, the drug-free nickel-titanium coated stent prepared in Comparative Example 1, and the bare nickel-titanium stent prepared in Comparative Example 2 after an adhesion experiment on human hepatobiliary cancer cells. In the images, a to c are, in order, the SEM images of the multifunctional anti-stenosis drug-coated stent prepared in Example 2, the drug-free nickel-titanium coated stent prepared in Comparative Example 1, and the bare nickel-titanium stent prepared in Comparative Example 2.

[0075] Figure 12The images show the antibacterial results of the multifunctional anti-stenosis drug-coated stent prepared in Example 1, the multifunctional anti-stenosis drug-coated stent prepared in Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3. In the images, a to c are the antibacterial results of the multifunctional anti-stenosis drug-coated stent prepared in Example 1, the multifunctional anti-stenosis drug-coated stent prepared in Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3, respectively. Detailed Implementation

[0076] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0077] All raw materials used in this invention are commercially available.

[0078] Example 1

[0079] (1) Preparation of TPU film: Weigh 50 g of TPU particles and use a casting machine to prepare a 20 μm thick TPU film at a temperature of 180 ℃ and a pressure of 1 MPa.

[0080] (2) Preparation of antitumor membrane and anticholesterol membrane: 5 g of polycaprolactone powder was dissolved in 50 mL of DMF, and then 0.5 g of 5-FU was added and dispersed evenly to prepare an antitumor solution; 5 g of polyvinyl alcohol powder was dissolved in 50 mL of water, and then 0.5 g of chlorhexidine was added and dispersed evenly to prepare an antibacterial solution; 20 μm thick antitumor membrane and anticholesterol membrane were prepared by casting machine at a temperature of 60 ℃ and a pressure of 1 MPa.

[0081] (3) Preparation of PLLA-TPU-based drug-loaded coating suspension slurry: Weigh 1.125 g of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 0.5189 g of trimethylbenzenealdehyde (Tf) and place them in a beaker. Dry at 60 ℃ for 12 h. Then, add 200 mL of acetonitrile to dissolve them. After dissolving, mix evenly and add 2 g of 5-FU. Add 40 mL of acetic acid at a rate of 4 mL / min. React at room temperature and 800 r / min for 12 h to obtain 5-FU@RT-COF suspension. Centrifuge at 10000 r / min, wash 5 times by centrifugation at 10000 r / min with 20 mL of acetonitrile, and dry in an oven at 80 ℃ for 24 h to obtain 5-FU@RT-COF powder. Weigh 5 g of PLLA and dissolve it in 50 mL of THF. Weigh 5 g of TPU and dissolve it in 50 mL of DMF. Stir and mix evenly. Weigh 0.5 g of 5 g of TPU and dissolve it in 50 mL of DMF. Add g of 5-FU@RT-COF powder to the mixture, stir and mix evenly, add 10 g of petroleum ether, sonicate at 60 W for 10 min, and place in an ice bath to obtain a PLLA-TPU-based drug-loaded coating suspension slurry.

[0082] (4) The PLLA-TPU-based drug-loaded coating suspension obtained in step (3) is uniformly sprayed onto the outer surface of the support using liquid flame spraying. The flow rate of the spraying material is 40 mL / min, the compressed air pressure is 0.2 MPa, and O2 is used as the combustion-supporting gas with a pressure of 0.4 MPa and a flow rate of 3 Nm³. 3 / h; using C2H2 as fuel, pressure 0.07 MPa, flow rate 1 Nm 3 / h; the concentric rotation speed of the support is 100 r / min, the distance between the flame gun and the outer surface of the support is 300 mm, the moving speed is 500 mm / s, the spraying angle is 120°, and the number of coating passes is 20, to obtain a nickel-titanium support loaded with a PLLA-TPU-based drug-loaded coating.

[0083] (5) The TPU membrane obtained in step (1), the anti-tumor membrane and the anti-biliary sludge membrane obtained in step (2) were subjected to corona treatment at a voltage of 10 kV for 2 min; the nickel-titanium stent loaded with PLLA-TPU-based drug-loaded coating was subjected to sandblasting treatment with sand particles of 120 mesh; under the conditions of a temperature of 80 ℃, a pressure of 1 MPa and a pressing time of 10 min, the three membranes were pressed onto the inner surface of the nickel-titanium stent loaded with PLLA-TPU-based drug-loaded coating in the order of anti-tumor membrane, TPU membrane and anti-biliary sludge membrane to obtain a multifunctional anti-stenosis drug-coated stent, the structural schematic diagram of which is shown below. Figure 1 As shown.

[0084] Example 2

[0085] The preparation method is the same as in Example 1, except that in step (3), the amount of 5-FU@RT-COF powder added to the PLLA-TPU-based drug-loaded coating suspension slurry is 1 g.

[0086] Comparative Example 1

[0087] The preparation method is the same as in Example 1, except that no drug was added to either the inner or outer coating of the nickel-titanium scaffold. The specific steps are as follows:

[0088] (1) Weigh 50 g of TPU particles and use a casting machine to prepare a 20 μm thick TPU film at a temperature of 180 ℃ and a pressure of 1 MPa.

[0089] (2) Weigh 5 g of polycaprolactone powder and dissolve it in 50 mL of DMF to prepare a polycaprolactone solution; weigh 5 g of polyvinyl alcohol powder and dissolve it in 50 mL of water to prepare a polyvinyl alcohol solution; use a casting machine to prepare a 20 μm thick polycaprolactone film and a polyvinyl alcohol film at a temperature of 60 ℃ and a pressure of 1 MPa respectively.

[0090] (3) Weigh 5 g of PLLA and dissolve it in 50 mL of THF. Weigh 5 g of TPU and dissolve it in 50 mL of DMF. Stir and mix evenly. Add 10 g of petroleum ether. The ultrasonic power is 60 W and the ultrasonic time is 10 min. Place in an ice bath to obtain PLLA-TPU coating suspension slurry.

[0091] (4) The PLLA-TPU coating suspension was uniformly sprayed onto the outer surface of the support using liquid flame spraying. The flow rate of the spraying material was 40 mL / min, and the compressed air pressure was 0.2 MPa. O2 was used as the combustion-supporting gas, with a pressure of 0.4 MPa and a flow rate of 3 Nm³. 3 / h; using C2H2 as fuel, pressure 0.07 MPa, flow rate 1 Nm 3 / h; the concentric rotation speed of the bracket is 100 r / min, the distance between the flame gun and the outer surface of the bracket is 300 mm, the moving speed is 500 mm / s, the spraying angle is 120°, and the number of coating passes is 20, to obtain a nickel-titanium bracket loaded with PLLA-TPU coating.

[0092] (5) The TPU film, polyvinyl alcohol film and polycaprolactone film obtained in steps (1) and (2) were corona treated with a voltage of 10kV and a treatment time of 2 min; the nickel-titanium scaffold loaded with PLLA-TPU coating was sandblasted with sand particles of 120 mesh; under the conditions of a temperature of 80 ℃, a pressure of 1MPa and a pressing time of 10 min, the three films were pressed onto the inner surface of the sprayed nickel-titanium scaffold loaded with PLLA-TPU coating in the order of polycaprolactone film, TPU film and polyvinyl alcohol film to obtain a nickel-titanium coated scaffold without drug loading.

[0093] Comparative Example 2

[0094] Bare nickel-titanium support structure, without any treatment.

[0095] Comparative Example 3

[0096] The preparation method is the same as in Example 1, except that the drug is added only to the outer coating of the nickel-titanium scaffold. The specific steps are as follows:

[0097] (1) Weigh 50 g of TPU particles and use a casting machine to prepare a 20 μm thick TPU film at a temperature of 180 ℃ and a pressure of 1 MPa.

[0098] (2) Weigh 5 g of polycaprolactone powder and dissolve it in 50 mL of DMF to prepare a polycaprolactone solution; weigh 5 g of polyvinyl alcohol powder and dissolve it in 50 mL of water to prepare a polyvinyl alcohol solution; use a casting machine to prepare a 20 μm thick polycaprolactone film and a polyvinyl alcohol film at a temperature of 60 ℃ and a pressure of 1 MPa respectively.

[0099] (3) Preparation of PLLA-TPU-based drug-loaded coating suspension slurry: Weigh 1.125 g of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 0.5189 g of tris(tf) and place them in a beaker. Dry at 60 ℃ for 12 h. Then, add 200 mL of acetonitrile to dissolve them. After dissolving, mix evenly and add 2 g of 5-FU. Add 40 mL of acetic acid at a rate of 4 mL / min. React at room temperature and 800 r / min for 12 h to obtain 5-FU@RT-COF suspension. Centrifuge at 10000 r / min, wash 5 times by centrifugation at 10000 r / min with 20 mL of acetonitrile, and dry in an oven at 80 ℃ for 24 h to obtain 5-FU@RT-COF powder. Weigh 5 g of PLLA and dissolve it in 50 mL of THF. Weigh 5 g of TPU and dissolve it in 50 mL of DMF. Stir and mix evenly. Weigh 0.5 g of 5 g of TPF. Add g of 5-FU@RT-COF powder to the mixture, stir and mix evenly, add 10 g of petroleum ether, sonicate at 60 W for 10 min, and place in an ice bath to obtain a PLLA-TPU-based drug-loaded coating suspension slurry.

[0100] (4) The PLLA-TPU coating suspension was uniformly sprayed onto the outer surface of the support using liquid flame spraying. The flow rate of the spraying material was 40 mL / min, and the compressed air pressure was 0.2 MPa. O2 was used as the combustion-supporting gas, with a pressure of 0.4 MPa and a flow rate of 3 Nm³. 3 / h; using C2H2 as fuel, pressure 0.07 MPa, flow rate 1 Nm 3 / h; the concentric rotation speed of the bracket is 100 r / min, the distance between the flame gun and the outer surface of the bracket is 300 mm, the moving speed is 500 mm / s, the spraying angle is 120°, and the number of coating passes is 20, to obtain a nickel-titanium bracket loaded with PLLA-TPU coating.

[0101] (5) The TPU film, polyvinyl alcohol film and polycaprolactone film obtained in steps (1) and (2) were corona treated with a voltage of 10kV and a treatment time of 2 min; the nickel-titanium scaffold loaded with PLLA-TPU coating was sandblasted with sand particles of 120 mesh; under the conditions of a temperature of 80 ℃, a pressure of 1MPa and a pressing time of 10 min, the three films were pressed onto the inner surface of the sprayed nickel-titanium scaffold loaded with PLLA-TPU coating in the order of polycaprolactone film, TPU film and polyvinyl alcohol film to obtain a nickel-titanium coated scaffold without drug-loaded film.

[0102] Sample Analysis

[0103] I. Detection and Analysis of 5-FU@RT-COF and RT-COF

[0104] (1) Infrared and XRD detection

[0105] The 5-FU@RT-COF powder, COF powder, and 5-FU powder synthesized in Example 1 were mixed with potassium bromide at a ratio of 1:100, ground, dried, and compressed into tablets. FT-IR analysis was performed to verify the successful synthesis of 5-FU@RT-COF and COF, and XRD was used to verify the successful synthesis and crystallinity of COF.

[0106] Figure 2 and Figure 3 The images show the infrared spectra of 5-FU@RT-COF powder, COF powder, and 5-FU powder prepared in Example 1, and the XRD pattern of COF. FT-IR spectroscopy confirms the successful synthesis of COF, with the C=N bond at 1623 cm⁻¹. -1 Expansion and contraction vibration at 1505cm -1 The C=C bond at this point originates from vibrations of the aromatic ring skeleton. Furthermore, the XRD spectrum shows a characteristic crystalline peak at 2θ = 5.7°, corresponding to the (100) crystal plane, further validating the effectiveness of the synthesis. The CF bond at 1223 cm⁻¹... -1 The discovery of this evidence proves the successful preparation of 5-FU@RT-COF powder.

[0107] (2) Microscopic morphological observation

[0108] The COF powder obtained in Example 1 was spread on conductive adhesive and sputtered with gold. The surface microstructure was observed using SEM.

[0109] Figure 4 The image shows the microstructure of the COF powder prepared in Example 1. The COF powder has a size of about 1 micrometer, a relatively uniform size distribution, and good monodispersity.

[0110] (3) 5-FU loading in 5-FU@RT-COF powder

[0111] By plotting the standard curve of 5-FU (e.g.) Figure 5 As shown in the figure, the concentration of 5-FU in the supernatant was measured using a UV spectrophotometer to calculate the 5-FU loading in the 5-FU@RT-COF powder. The formula for calculating the loading (in g / g) is as follows:

[0112]

[0113] The test showed that the concentration of 5-FU in the supernatant was 9.8426 mg / mL. Calculations showed that the 5-FU loading in the 5-FU@RT-COF powder prepared in Example 1 was 0.431 g / g.

[0114] (4) Cytotoxicity assessment of RT-COF powder

[0115] The toxicity of 5-FU@RT-COF powder on human hepatobiliary carcinoma cells (RBE cells, purchased from Wuhan Pronosai Life Science Technology Co., Ltd., catalog number CL-0191) was evaluated using a CCK8 assay kit.

[0116] Figure 6 The figure shows the toxicity test results of the RT-COF powder prepared in Example 1 on human hepatobiliary cancer cells. As shown in the figure, the RT-COF powder prepared in Example 1 has good biocompatibility. When the concentration of RT-COF powder reaches 1 mg / mL, the inhibition rate of RT-COF powder on cholangiocarcinoma cells is only 20%.

[0117] II. Testing of Multifunctional Anti-Stenosis Drug-Coated Stents

[0118] (1) Microstructure test of PLLA-TPU-based drug-loaded coating

[0119] The multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1 were subjected to gold sputtering treatment, and their outer surface micromorphology was observed using SEM.

[0120] Figure 7 The figures show the external surface microstructures of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 1. Figures a through c show the external surface microstructures of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, respectively. As shown in the figures, the external surface of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2 exhibits good melting state, and the uniform distribution of 5-FU@RT-COF powder on the coating surface can be observed.

[0121] (2) PLLA-TPU-based drug-loaded coating thickness test

[0122] The multifunctional anti-stenosis drug-coated stent prepared in Example 1 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1 were cut, inlaid and polished, and then sputter-coated with gold. The coating thickness on their outer surfaces was measured by SEM.

[0123] Figure 8The figures show cross-sectional SEM images of the multifunctional anti-stenosis drug-coated stent prepared in Example 1 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, where a and b are cross-sectional SEM images of the multifunctional anti-stenosis drug-coated stent prepared in Example 1 and the drug-free nickel-titanium coated stent prepared in Comparative Example 1, respectively. As shown in the figures, Example 1 and Comparative Example 1 prepared relatively uniform coatings by suspension flame spraying. The coatings were relatively dense with a small number of pores, and the thickness was about 100 μm.

[0124] (3) Drug release assay of multifunctional anti-stenosis drug-coated stent

[0125] Drug release experiments were conducted on the multifunctional anti-stenosis drug-coated stent prepared in Example 2 in PBS at pH 5.5 and pH 7.4.

[0126] Figure 9 The figure shows the release curves of 5-FU of the multifunctional anti-stenosis drug-coated stent prepared in Example 2 in PBS at pH 5.5 and pH 7.4. As shown in the figure, the multifunctional anti-stenosis drug-coated stent prepared in Example 2 releases 5-FU faster in PBS at pH 5.5 than at pH 7.4, and the overall release is faster over a period of 14 days. This is related to the positively charged protonation of COF and 5-FU in the acidic environment, which accelerates the release of 5-FU, as well as the rapid degradation and molecular conformational unfolding of the organic polymer matrix in the acidic environment. This indicates that the pH response mechanism of the present invention is successfully effective.

[0127] (4) Evaluation of the tumor cell inhibition effect of multifunctional anti-stenosis drug-coated stents

[0128] The multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2, the drug-free nickel-titanium coated stent prepared in Comparative Example 1, the bare nickel-titanium stent prepared in Comparative Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3 were co-cultured with human hepatobiliary cancer cells for three days and detected by CCK8 assay kit.

[0129] Figure 10Figure 1 shows the inhibitory effects of the multifunctional anti-stenosis drug-coated stents prepared in Examples 1 and 2, the drug-free nickel-titanium coated stent prepared in Comparative Example 1, the bare nickel-titanium stent prepared in Comparative Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3 on human hepatobiliary cholangiocarcinoma cells. As shown in the figure, the inhibition rates of human hepatobiliary cholangiocarcinoma cells in Example 1 during co-culture for 1 day, 2 days, and 3 days were 51.5%, 75.5%, and 90.6%, respectively. The inhibition rates of human hepatobiliary cholangiocarcinoma cells in Example 2 during co-culture for 1 day, 2 days, and 3 days were 58.4%, 84.1%, and 94.4%, respectively, showing a better inhibitory effect on human hepatobiliary cholangiocarcinoma cells than that in Example 1. This is attributed to the increased drug content. Comparative Example 1 showed inhibition rates of 6.6%, 5.2%, and 3.3% against human hepatobiliary cholangiocarcinoma cells during co-culture for 1, 2, and 3 days, respectively. Comparative Example 3 showed inhibition rates of 28.3%, 46.5%, and 68.4% against human hepatobiliary cholangiocarcinoma cells during co-culture for 1, 2, and 3 days, respectively. The coating of Comparative Example 1 showed a slightly better inhibitory effect on human hepatobiliary cholangiocarcinoma cells than the bare nickel-titanium scaffold of Comparative Example 2. This may be related to the fact that the degradation products of the coating polymer have a certain inhibitory effect on human hepatobiliary cholangiocarcinoma cells. Comparative Example 3 showed a lower inhibitory effect on human hepatobiliary cholangiocarcinoma cells than Example 1, which indicates that the antitumor effect of the inner drug-loaded membrane is very important.

[0130] (5) Observation on the adhesion of multifunctional anti-stenosis drug-coated stents to human hepatobiliary cancer cells

[0131] The growth of cells attached to the coating surface was detected using SEM. The specific steps were as follows: Example 2, Comparative Example 1, and Comparative Example 2 were sterilized with UV light for 2 hours, and cells were inoculated onto the material surface at a density of 2000 cells / cm². 2 Human hepatobiliary cancer cells were grown in a cell culture chamber at 37 ℃, 100% humidity, and 5% carbon dioxide. After growing on the coating surface for 3 days, the human hepatobiliary cancer cells were washed three times with PBS, dehydrated with 25% ethanol solution for 5 minutes, 50% ethanol solution for 5 minutes, 75% ethanol solution for 5 minutes, 90% ethanol solution for 5 minutes, and 100% ethanol solution for 10 minutes, then fixed with 4% paraformaldehyde for 4 hours, and finally dried at 37 ℃ for 12 hours.

[0132] Figure 11The images show scanning electron microscope (SEM) images of the multifunctional anti-stenosis drug-coated scaffold prepared in Example 2, the drug-free nickel-titanium coated scaffold prepared in Comparative Example 1, and the bare nickel-titanium scaffold prepared in Comparative Example 2 after adhesion experiments to human hepatobiliary cancer cells. Figures a through c show the SEM images of the multifunctional anti-stenosis drug-coated scaffold prepared in Example 2, the drug-free nickel-titanium coated scaffold prepared in Comparative Example 1, and the bare nickel-titanium scaffold prepared in Comparative Example 2, respectively. As shown in the figures, the surface of Example 2 showed virtually no cell adhesion, exhibiting good anti-cell adhesion properties. Figure 11 (a) In comparison examples 1 and 2, the surfaces also showed virtually no cell adhesion, exhibiting good anti-cell adhesion properties. Figure 11 The anti-adhesion properties of b and c in the comparison with those of 2 may be due to the fact that cells cannot adhere well to this surface.

[0133] (6) Evaluation of the antibacterial effect of multifunctional anti-stenosis drug-coated stents

[0134] The antibacterial properties of the stents were determined using the standard plate count method. The specific steps are as follows: Nickel-titanium stents from Examples 1, 2, and Comparative Example 3 were placed in 6-well plates and sterilized under UV light for 30 minutes. 3 ml of a 1×10⁻⁶ solution was added. 6 CFU / mL Escherichia coli culture was co-cultured in a 37 ℃ incubator for 24 hours. 100 μL of the culture was then spread on a solid culture medium and cultured for 16 hours. Data was then recorded by taking pictures.

[0135] Figure 12 Figures show the antibacterial results of the multifunctional anti-stenosis drug-coated stent prepared in Example 1, the multifunctional anti-stenosis drug-coated stent prepared in Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3. Figures a through c show the antibacterial results of the multifunctional anti-stenosis drug-coated stent prepared in Example 1, the multifunctional anti-stenosis drug-coated stent prepared in Example 2, and the drug-free nickel-titanium coated stent prepared in Comparative Example 3, respectively. As shown in the figures, the antibacterial results of Examples 1 and 2 are excellent, while Comparative Example 3, which lacks an inner antibacterial layer, exhibits poor antibacterial performance, highlighting the necessity of an inner antibacterial layer.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional anti-stenosis drug-eluting stent, comprising a nickel-titanium stent, wherein the outer surface of the nickel-titanium stent is coated with a PLLA-TPU-based drug-loaded coating, characterized in that, The PLLA-TPU-based drug-loaded coating includes a COF powder containing a Schiff base structure loaded with an antitumor drug I. The antitumor drug I is at least one of cisplatin, carboplatin, oxaliplatin, 5-fluorouracil, methotrexate, doxorubicin, paclitaxel, sorafenib, or gemcitabine. The COF powder containing the Schiff base structure is obtained by a nucleophilic addition reaction between an amine monomer and an aldehyde monomer, followed by further dehydration. The inner surface of the nickel-titanium stent is coated with a drug-loaded membrane, which consists of an anti-tumor membrane, a TPU membrane, and an anti-biliary sludge membrane, starting from the inner surface of the nickel-titanium stent.

2. The multifunctional anti-stenosis drug-coated stent according to claim 1, characterized in that, The antitumor membrane is loaded with antitumor drug II, which is at least one of cisplatin, carboplatin, oxaliplatin, 5-fluorouracil, methotrexate, doxorubicin, paclitaxel, sorafenib, or gemcitabine.

3. The multifunctional anti-stenosis drug-coated stent according to claim 2, characterized in that, The loading amount of antitumor drug I in the PLLA-TPU-based drug-loaded coating is 0.2-5%; the loading amount of antitumor drug II in the antitumor membrane is 0.9-10%.

4. The multifunctional anti-stenosis drug-coated stent according to claim 1, characterized in that, The anti-biliary sludge membrane is loaded with an antibacterial agent, which is at least one of benzalkonium chloride, chlorhexidine, polymyxin B, vancomycin, gentamicin, erythromycin, or levofloxacin.

5. The multifunctional anti-stenosis drug-coated stent according to claim 4, characterized in that, The loading of antibacterial agent in the anti-sludge membrane is 0.9~10%.

6. The method for preparing the multifunctional anti-stenosis drug-coated stent according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Preparation of drug-loaded membrane; (2) Preparation of PLLA-TPU-based drug-loaded coating suspension slurry: Under the action of a catalyst, amine monomers, aldehyde monomers and antitumor drugs are placed in acetonitrile for Schiff base reaction to obtain drug-loaded COF suspension. After centrifugation, washing and drying, drug-loaded COF powder is obtained. The drug-loaded COF powder is dispersed in the oil phase and then added to a mixed solution of PLLA and TPU for ultrasonication to obtain PLLA-TPU-based drug-loaded coating suspension slurry. (3) The PLLA-TPU-based drug-loaded coating suspension slurry obtained in step (2) is coated onto the outer surface of the nickel-titanium scaffold by liquid flame spraying to obtain a nickel-titanium scaffold loaded with PLLA-TPU-based drug-loaded coating. (4) The drug-loaded membrane obtained in step (1) is laminated onto the inner surface of the nickel-titanium stent obtained in step (3) to obtain a multifunctional anti-stenosis drug-coated stent.

7. The method for preparing the multifunctional anti-stenosis drug-coated stent according to claim 6, characterized in that, In step (1), the method for preparing the drug-loaded membrane includes the following steps: S1. TPU particles are prepared into TPU film using a casting machine; S2. The mixed solution of antitumor drug II and organic substance I, and the mixed solution of antibacterial agent and organic substance II are respectively prepared into antitumor membrane and anti-biliary sludge membrane by casting machine.

8. The multifunctional anti-stenosis drug-coated stent according to claim 7, characterized in that, In step S2, the mass ratio of antitumor drug II to organic matter I in the antitumor membrane is 1~10:100, and the mass ratio of antibacterial agent to organic matter II in the anti-biliary sludge membrane is 1~10:

100.

9. The method for preparing the multifunctional anti-stenosis drug-coated stent according to claim 6, characterized in that, In step (4), the drug-loaded membrane is subjected to corona treatment with a voltage of 10~15 kV and a treatment time of 1~2 min; the nickel-titanium scaffold needs to be sandblasted with a sand particle size of 60~120 mesh.

Images