A drug coating and drug stent capable of in-situ controlled release of nitric oxide in vivo, and preparation method and application thereof

Abstract

The present invention relates to a drug coating and drug stent capable of in-situ controllable release of nitric oxide in vivo, and a preparation method and application thereof, wherein the drug coating comprises an intermediate layer, a polymer layer and a drug layer; wherein the polymer layer is located between the intermediate layer and the drug layer, the intermediate layer comprises polyparaxylene, and the polymer layer comprises a mesh copolymer capable of controllable release of nitric oxide in response to near-infrared light. The present invention initiates in-situ polymerization of a mesh copolymer layer on the surface of the intermediate layer by ultraviolet light, and the polymer layer has the function of controllable release of nitric oxide in response to near-infrared light, can be stably loaded on the surface of the intermediate layer, and will not cause sudden release of nitric oxide or loss of the coating due to shedding. The present invention uses fluorine-containing gas to perform patterned etching on the stress concentration area of ​​the stent, introduces fluorine ions to increase the hydrophobicity of the material surface, and further improves the binding force of the stent drug coating.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine, and in particular to a drug coating and a drug stent capable of in-situ controllable release of nitric oxide in vivo, as well as a preparation method and application thereof. Background Art

[0002] Nitric oxide (NO), as a typical therapeutic gas molecule, is closely related to physiological and pathological processes such as wound healing, cancer, diabetes, and especially cardiovascular disease. Studies have shown that the continuous release of NO by endothelial cells is the basis for maintaining cardiovascular homeostasis and regulating vascular tension. Efficient NO production can inhibit platelet activation and smooth muscle cell proliferation, thereby preventing thrombosis and neointimal hyperplasia. Therefore, it is an effective way to prepare functional stents by regulating the body's stimulation of NO to the diseased area and the in situ production of NO by the stent material, inhibiting coagulation and smooth muscle hyperplasia to promote endothelialization.

[0003] Although human blood contains a variety of endogenous NO donors S-nitrosothiols, which can release NO under the catalysis of glutathione peroxidase in the body, this spontaneous reaction in the body has a low efficiency in releasing NO, so the therapeutic effect is not good. On the other hand, it is a difficult technical problem to load S-nitrosothiol substances on the stent stably for a long time and release them continuously in the body. Therefore, the researchers proposed to modify the stent surface to accelerate the in situ catalytic release of NO, thereby inhibiting smooth muscle hyperplasia and accelerating endothelialization.

[0004] CN113599581A discloses a cardiovascular stent polymer coating with a controllable catalytic nitric oxide production function, a preparation method and an application thereof, wherein regenerated silk fibroin and chitosan are dissolved in a hexafluoroisopropanol solution respectively, mixed in a certain proportion and then coated on the inner side of the cardiovascular stent, and then dried and immersed in Cu 2+ The invention simplifies the preparation method, but it is difficult to avoid Cu 2+ The biological toxicity produced in the human body poses a higher risk.

[0005] CN104208761A discloses a method for preparing an anticoagulant material with the function of inducing catalytic release of endogenous NO, wherein a structure with disulfide bonds or diselenide bonds at both ends containing amine or thiol groups is constructed on the surface of the material, and NO molecules are continuously released by in-situ catalyzing NO donors in the blood, thereby inhibiting the activation and aggregation of platelets, inhibiting the proliferation of smooth muscle cells, and protecting the vascular endothelium. The reaction system of this method is complex, and it is difficult to ensure that the coating will not fall off during the pushing process of the device or when it is released.

[0006] Generally, an ideal drug-coated stent can not only promote the proliferation of active endothelial cells so that they can completely cover the stent surface, thereby avoiding the problem of late stent lumen loss caused by poor stent endothelial healing, but also release anti-proliferative drugs within a specific time after stent implantation to inhibit the short-term excessive proliferation of smooth muscle, thereby preventing the vascular restenosis rate from being too high. However, the current design concepts of new drug-eluting stents and the effects of the drugs they carry are mostly aimed at reducing intimal hyperplasia and restenosis, but at the same time these drugs also hinder the process of endothelialization, and some drugs are even more effective in inhibiting endothelial cells. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a drug coating, a drug stent and a preparation method and application thereof for in situ controllable release of nitric oxide in vivo. The present invention prepares a layer of polymer on the surface of the intermediate layer, and the polymer layer has a near-infrared light-responsive nitric oxide controllable release performance. The drug layer is patterned to stably release the drug, thereby optimizing the anti-proliferation and endothelial remodeling performance of the drug stent. In addition, the present invention modifies the interface of the stent drug coating, so that the drug coating is not easy to fall off and the stent has good biocompatibility and safety.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a drug coating for in situ controllable release of nitric oxide in vivo, the drug coating comprising an intermediate layer, a polymer layer and a drug layer; wherein the polymer layer is located between the intermediate layer and the drug layer, the intermediate layer contains polyparaxylene, and the polymer layer contains a mesh copolymer having the ability to release nitric oxide in response to near-infrared light.

[0010] The present invention coats a layer of polymer on the surface of the intermediate layer, and the polymer layer has the performance of controlled release of NO in response to near infrared light (NIR), and because it is in the form of a polymer, it can exist stably. The intermediate layer, the polymer layer and the drug layer are all hydrophobic coatings, and there is a strong hydrophobic interaction between the three layers, and they have good bonding strength. Among them, after the intermediate layer is treated with plasma, not only the surface hydrophobicity is enhanced, but also an in-situ polymerization reaction site is formed, which is combined with the polymer layer through chemical bonds, so the polymer layer and the intermediate layer have excellent bonding strength. Furthermore, the polymer layer of the present invention is a mesh copolymer, which has a hydrophobic and rough surface at the microscopic level, and also forms excellent bonding force with the subsequently sprayed drug layer; usually after the implant device is implanted in the human body, the protein adsorption occurring on its surface will directly affect or even determine the therapeutic effect of the device. After the drug layer is degraded, the internal hydrophobic polymer layer is exposed, which on the one hand promotes the adsorption of proteins such as albumin and fibronectin, facilitates the attachment of endothelial cells, and promotes endothelialization; more importantly, it can stimulate the polymer on the surface of the stent to continuously produce nitric oxide through NIR, which can controllably promote endothelial cell proliferation and inhibit smooth muscle cell proliferation.

[0011] Preferably, the thickness of the intermediate layer is 0.5-2 μm (for example, it may be 0.5 μm, 0.75 μm, 1 μm, 1.25 μm, 1.5 μm, 1.75 μm or 2 μm, etc.), the thickness of the polymer layer is 3-10 μm (for example, it may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc.), and the thickness of the drug layer is 5-10 μm (for example, it may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc.).

[0012] Preferably, the polyparaxylene includes any one of polyparaxylene C, polyparaxylene N, polyparaxylene D, polyparaxylene F or polyparaxylene HT, or a combination of at least two thereof.

[0013] Preferably, the weight average molecular weight of the polyparaxylene is 500-5000 kDa (for example, it may be 500 kDa, 1000 kDa, 1500 kDa, 2000 kDa, 2500 kDa, 3000 kDa, 3500 kDa, 4000 kDa, 4500 kDa or 5000 kDa, etc.).

[0014] Preferably, the drug layer contains a polymer and a drug.

[0015] Preferably, the polymer includes any one of PLA, PGA, PCL, PLGA, PCL-b-PDLLA, PCL-PDLLA-PGA or PCL-PGA-PDLLA, or a combination of at least two of them, and the drug includes one of anti-proliferative drugs, anti-coagulant drugs, anti-thrombotic drugs, anti-tumor drugs, anti-inflammatory drugs or gene therapy drugs, or a combination of at least two of them.

[0016] Preferably, the drug is selected from one or a combination of at least two of rapamycin, methylated rapamycin, everolimus, zotarolimus or paclitaxel.

[0017] Preferably, the network copolymer has the ability of controlled release of nitric oxide in response to near infrared light.

[0018] Preferably, the wavelength of the near-infrared light is 800-900 nm (for example, it may be 800 nm, 820 nm, 840 nm, 860 nm, 880 nm or 900 nm, etc.).

[0019] Preferably, the raw materials for preparing the network copolymer include acrylic ester monomers, a compound capable of releasing nitric oxide, a photoinitiator, a solvent and a cross-linking agent.

[0020] Preferably, the acrylic ester monomer includes any one or a combination of at least two of n-butyl methacrylate, 2-methacryloyloxyethyl phosphorylcholine, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, sulfobetaine methyl acrylate, 2-methacryloyloxyethyl sulfobetaine, acrylamidopropyl carboxybetaine or 2-methacryloyloxyethyl carboxybetaine.

[0021] Preferably, the structure of the compound capable of releasing nitric oxide is as shown in Formula I;

[0022] Formula Ⅰ.

[0023] Preferably, the photoinitiator includes any one of Michs ketone, benzophenone, 2,2-dimethoxy-2-acetophenone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 1-hydroxycyclohexylphenylpropiotone, 2-hydroxy-2methyl-1-phenylpropiotone, 2-methyl-1-[4-(methylthiophenyl)-2-morpholinyl-1-propanone] or 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, or a combination of at least two thereof.

[0024] Preferably, the solvent includes any one of dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide, or a combination of at least two thereof.

[0025] Preferably, the crosslinking agent includes any one or a combination of at least two of N,N-methylenebisacrylamide, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, hexanediol dimethacrylate or 1,4-butanediol dimethacrylate.

[0026] Preferably, the preparation method of the network copolymer comprises: using dichloromethane as a solvent, adding a compound as shown in formula I, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide in a molar ratio of (1-6):(2-10):(1-20):(0.1-1), and after completely dissolving in dichloromethane, adding benzophenone, wherein the amount of the initiator benzophenone is 0.1%-1% (for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%) of the total mass of the compound as shown in formula I, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide, and after forming a homogeneous solution, filtering with a filter membrane, and the solid content of the solution is 3 wt%-20wt% (for example, it can be 3 wt%, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, etc.). wt%, 15 wt%, 17 wt% or 20 wt%, etc.), using ultraviolet light to initiate polymerization of each monomer to obtain the network copolymer.

[0027] The specific point values ​​(1~6) above can be selected as 1, 2, 3, 4, 5 or 6, etc.

[0028] The specific point values ​​(2~10) above can be selected from 2, 3, 4, 5, 6, 7, 8, 9 or 10, etc.

[0029] The specific point values ​​(1~20) mentioned above can be selected as 1, 3, 5, 7, 10, 12, 14, 16, 18 or 20, etc.

[0030] The specific point values ​​of the above (0.1~1) can be selected as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.

[0031] Preferably, the preparation method of the network copolymer comprises: feeding in a molar ratio of (1-6):(2-10):(1-20):(0.1-1), dissolving the compound shown in formula I, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide in dichloromethane in sequence, adding a photoinitiator benzophenone after complete dissolution, wherein the amount of benzophenone is 0.1%-1% of the total mass of all monomers, the solid content of the solution is 3 wt%-20 wt%, and after forming a homogeneous solution, filtering once with a filter membrane with a pore size of 1 μm, and using ultraviolet light to initiate polymerization of each monomer to obtain the network copolymer.

[0032] The network copolymer structure obtained by the present invention is as follows Figure 1 As shown in Figure 2, the process of NO release from the copolymer under NIR light is as follows: Figure 2 shown.

[0033] In a second aspect, the present invention provides use of the drug coating as described in the first aspect in preparing a medical device with drug delivery function.

[0034] Preferably, the medical device includes a drug-eluting stent and / or a drug-eluting balloon.

[0035] In a third aspect, the present invention provides a drug stent, the surface of which is coated with the drug coating described in the first aspect, and the drug stent comprises a stent body, an intermediate layer, a polymer layer and a drug layer from the inside to the outside.

[0036] At present, the commonly used preparation method of drug-eluting stents is to prepare a mixed solution of polymer and drug, apply it to the surface of the stent, and after the solvent evaporates and completely dries, a layer of polymer drug coating is formed on the surface of the stent, wherein the polymer is mostly a homopolymer of D, L-lactide, glycolide, ε-caprolactide, or a copolymer of the two or the three. Such polymers have poor bonding strength with metal substrates, such as 316L stainless steel, nickel-titanium alloy, magnesium alloy, cobalt-based alloy, etc., and are prone to fall off during the sterilization, placement and long-term implantation of the stent.

[0037] In order to enhance the bonding force between the polymer drug coating and the metal stent, the present invention sets a polyparaxylene intermediate layer between the metal stent and the drug coating. Polyparaxylene has the advantages of chemical inertness, good biocompatibility, appropriate mechanical strength, easy deposition, and the ability to firmly adhere to the surface of the metal substrate in physiological media.

[0038] Preferably, the material of the stent body includes any one of stainless steel, nickel-titanium alloy or cobalt-chromium alloy.

[0039] In a fourth aspect, the present invention provides a method for preparing the drug stent as described in the third aspect, wherein the method for preparing the drug stent comprises sequentially preparing an intermediate layer, a polymer layer and a drug layer on the surface of the stent body.

[0040] Preferably, the preparation method of the drug stent specifically comprises the following steps:

[0041] S1. Immerse the stent in a silane solution, wash and dry, and deposit polyparaxylene on the surface of the stent;

[0042] S2. The stent prepared in step S1 is treated with plasma;

[0043] S3. The raw materials for preparing the polymer layer are mixed uniformly to obtain a polymer layer solution;

[0044] S4. Spraying the polymer layer solution onto the surface of the stent and curing it with ultraviolet light;

[0045] S5. The raw materials for preparing the drug layer are mixed uniformly to obtain a drug layer solution;

[0046] S6. Apply the drug layer solution to the surface of the stent prepared in step S4, and obtain the drug stent after drying.

[0047] Optionally, steps S4 and S7 may be coated by dipping, spraying or ultrasonic atomization spraying.

[0048] The intermediate layer of the present invention uses polyparaxylene. Since the surface of polyparaxylene itself is smooth, dense and pinhole-free, if a polymer layer is directly prepared on the surface of the intermediate layer and then the drug layer is sprayed, the polymer layer will easily fall off and the drug layer will be lost due to the weak bonding force between the polymer layer and the intermediate layer, resulting in a significant reduction in the therapeutic effect of the stent. Furthermore, during actual use, when the stent enters a catheter with different inner diameters or to adjust the implantation position, the stent may be contracted or expanded multiple times, and the stress concentration area of ​​the stent is frequently deformed. The drug coating there needs to be repeatedly stretched and compressed compared to the drug coating in other parts of the stent, and is very likely to crack, peel off or even fall off, posing a greater safety risk and affecting the therapeutic effect.

[0049] In order to solve the above technical problems, the present invention performs plasma treatment on the intermediate layer, and the entire surface of the intermediate layer is treated with inert gas to introduce free radicals, thereby providing more active sites for subsequent polymerization reactions, and the surface roughness of the intermediate layer is increased, and the hydrophobicity is increased. Thereafter, the polymer layer solution is sprayed on the surface of the intermediate layer, and polymerization is initiated by ultraviolet light to form a polymer layer in situ on the surface of the intermediate layer. At this time, the polymer layer and the intermediate layer are connected by covalent bonds. At the same time, the increase in interface roughness gives it a stronger hydrophobic interaction, and the interlayer bonding force between the two is also enhanced accordingly.

[0050] Preferably, before step S1, the surface of the stent is also cleaned by ultrasonic cleaning in acetone for 2 to 5 min (for example, 2 min, 3 min, 4 min or 5 min, etc.), then ultrasonic cleaning in anhydrous ethanol for 5 to 10 min (for example, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc.), and then taking out and drying naturally.

[0051] Preferably, the silane in the silane solution in step S1 includes any one of γ-methacryloxypropyltrimethoxysilane (KH570), 3-glycidyloxypropyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), vinyltrimethoxysilane (A-171), vinyltri(β-methoxyethoxy)silane (A-172), vinyltriethoxysilane (A-151), bis-[γ-(triethoxysilyl)propyl]-tetrasulfide (BTSPS), 1,2-bis(triethoxysilyl)ethane (BTESE) or bis[3-(trimethoxysilyl)propyl]amine (BTMSPA) or a combination of at least two thereof.

[0052] Preferably, the solvent in the silane solution in step S1 is any one of methanol, ethanol, propanol, isopropanol or ultrapure water, or a combination of at least two of them.

[0053] Preferably, the concentration of the silane solution in step S1 is 1-3 wt % (for example, 1 wt %, 1.5 wt %, 2wt %, 2.5 wt % or 3 wt %, etc.).

[0054] Preferably, the pH value of the silane solution in step S1 is 3-10 (for example, 3, 4, 5, 6, 7, 8, 9 or 10, etc.), and the reagent for adjusting the pH is any one of acetic acid, hydrochloric acid, ammonia water or sodium hydroxide.

[0055] Preferably, the preparation method of the silane solution in step S1 comprises: dissolving silane in a solvent, adjusting the pH and vigorously stirring for 30 to 120 min (for example, 30 min, 50 min, 70 min, 90 min or 120 min, etc.).

[0056] Preferably, the immersion time of immersing the stent in the silane solution in step S1 is 30 to 120 min (for example, 30 min, 50 min, 70 min, 90 min or 120 min, etc.).

[0057] Preferably, the drying temperature in step S1 is 40-65°C (for example, 40°C, 45°C, 50°C, 55°C, 60°C or 65°C, etc.), and the drying time is 30-120 min (for example, 30 min, 50 min, 70 min, 90 min or 120 min, etc.).

[0058] Preferably, the gas source for the plasma treatment in step S2 is an inert gas.

[0059] Preferably, the inert gas includes helium (He) and / or argon (Ar).

[0060] Preferably, the power of the plasma treatment in step S2 is 40-60 W (for example, 40, 45, 50, 55 or 60, etc.), and the time is 30-60 min (for example, 30 min, 40 min, 45 min, 50 min or 60 min, etc.).

[0061] Preferably, the UV light density of the UV curing in step S4 is 30-50 mW / cm 2 (For example, it can be 30mW / cm 2 、35 mW / cm 2 、38 mW / cm 2 , 40 mW / cm 2 , 42 mW / cm 2 , 45 mW / cm 2 or 50 mW / cm 2 The curing time is 30 to 60 min (for example, 30 min, 40 min, 45 min, 50 min or 60 min, etc.).

[0062] Preferably, step S4 comprises: spraying the polymer layer solution onto the surface of the stent, curing with ultraviolet light, and plasma etching and patterning the surface of the stress concentration area during the contraction and / or expansion process of the prepared stent.

[0063] Preferably, the stress concentration area during the contraction and / or expansion of the stent includes the intersection of the stent beams of the drug stent.

[0064] Preferably, the plasma etching gas source is a fluorine-containing gas, and the fluorine-containing gas includes sulfur hexafluoride (SF 6 ), tetrafluoromethane (CF 4 ), tetrafluoroethylene (C 2 F 4 ), hexafluoroethane (C 2 F 6 ), hexafluoropropylene (C 3 F6 ) or octafluorocyclobutane (C 4 F 8 ) or a combination of at least two of them.

[0065] The present invention performs a fluorine-containing gas patterned etching treatment on the stress concentration area of ​​the stent, introduces a fluorine-containing group on the surface of the polymer layer in the stress concentration area, and enhances its surface hydrophobicity, thereby having a stronger hydrophobic interaction between the polymer layer in the area and the hydrophobic drug layer, thereby having a stronger bonding force. Combined with the patterned etching treatment, the rough surface of the polymer layer contributes a larger specific surface area and more mechanical cross-linking, thereby improving the interface shear strength of the composite system of the polymer layer and the drug layer, and further improving the bonding force between the two to cope with the mechanical stripping force caused by repeated stretching and compression in the area. Thereby preventing the drug layer from cracking, peeling or falling off during the contraction or expansion of the drug stent.

[0066] Preferably, step S6 comprises: coating the drug layer solution onto the surface of the stent prepared in step S4, drying, and performing plasma etching patterning on the surface of the drug layer to obtain the drug stent.

[0067] Preferably, the gas source for the plasma etching is an inert gas.

[0068] Preferably, after the plasma etching patterning, the drug content ratio of the etched area to the unetched area is (0.7~0.9):1.

[0069] The specific point values ​​of the above (0.7~0.9) can be selected as 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88 or 0.9, etc.

[0070] Most existing coronary stent drugs are coated with one or more layers of drug-containing polymer coatings on the stent surface. The active drugs currently used have been proven to not only inhibit smooth muscle proliferation, but also inhibit the proliferation and coverage of endothelial cells.

[0071] In order to solve the above technical problems, the present invention promotes endothelial remodeling by controlling the release of NO by the polymer layer. Furthermore, inert gas etching is performed on the surface of the drug layer, so that there are blank or low-dose areas in the drug coating of the microscopic area of ​​the stent. Due to this concentration difference, the drug release can present a relatively stable curve, that is, concentration balance, thereby improving the overall utilization of the drug, thereby avoiding the adverse effects of local drug accumulation on the endothelialization process. On the contrary, if no patterning treatment is performed, the thickness of the drug coating in the microscopic area is uniform, and the simultaneous release of drugs will cause the drug concentration in the microscopic area to accumulate, and the drug concentration will present a peak-shaped curve. In this case, the effective utilization rate of the drug is low, not only will part of the drug be lost, but the high concentration of the drug will also inhibit the endothelialization process.

[0072] Preferably, the plasma etching patterning in step S4 and the plasma etching patterning in step S6 are each independently any one of the following patterning methods (I), (II) or (III):

[0073] (I) at least two polygonal depressions or circular depressions arranged in an array;

[0074] (II) at least two parallel first grooves and at least two parallel second grooves, the first grooves and the second grooves intersecting each other;

[0075] (III) Based on the patterning method (II), in the closed area surrounded by any two adjacent first grooves and any two adjacent second grooves, there is a polygonal depression or a circular depression as described in the patterning method (I).

[0076] Preferably, the etching depth of the polygonal recess, the circular recess, the first groove and the second groove is each independently 100~6000 nm (for example, it can be 100 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, 5500 nm or 6000 nm, etc.).

[0077] When patterning is performed on the surface of the polymer layer, in order to enhance the binding force of the drug layer, the etching depths of the polygonal depression, the circular depression, the first groove and the second groove are each independently 100-1500 nm (for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 700 nm, 1000 nm, 1200 nm or 1500 nm, etc.); when patterning is performed on the surface of the drug layer, in order to balance the regional drug concentration, the etching depths of the polygonal depression, the circular depression, the first groove and the second groove are each independently 2500-6000 nm (for example, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, 5500 nm or 6000 nm, etc.), that is, the thickness of the drug layer in the etched area is 70%-90% of the thickness of the drug coating in the unetched area of ​​the stent, and accordingly, in any microscopic area, the drug content in the etched area and the drug content in the unetched area of ​​the stent also present this proportional relationship.

[0078] Preferably, the cross-sectional area of ​​the polygonal depression and the circular depression is independently 100-5000 μm 2 (For example, it can be 100 μm 2 , 500 μm 2 , 1000 μm 2 , 2000 μm 2 , 3000 μm 2 , 4000 μm 2 or 5000 μm 2 wait).

[0079] Preferably, the center distance between any two adjacent polygonal recesses and any two adjacent circular recesses is independently 50-200 μm (eg, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm or 200 μm, etc.).

[0080] Preferably, the width of the first groove and the second groove is independently 10-100 μm (for example, 10 μm, 20 μm, 40 μm, 50 μm, 60 μm, 80 μm or 100 μm, etc.).

[0081] Preferably, the distance between any two adjacent first grooves and any two adjacent second grooves is independently 10-100 μm (eg, 10 μm, 20 μm, 40 μm, 50 μm, 60 μm, 80 μm or 100 μm, etc.).

[0082] In a fifth aspect, the present invention provides a stent with stable drug release, wherein the stent with stable drug release is prepared using the preparation method of the drug stent described in the fourth aspect.

[0083] In a sixth aspect, the present invention provides a method for balancing drug concentration, the method for balancing drug concentration comprising delivering the drug using the drug stent described in the third aspect or the drug-stable release stent described in the fifth aspect.

[0084] Other specific point values ​​within the above numerical ranges can be selected and will not be described in detail here.

[0085] Compared with the prior art, the present invention has the following beneficial effects:

[0086] (1) The present invention provides a drug coating that can controllably release NO in situ in vivo, wherein the polymer layer contains a mesh copolymer that can controllably release NO in response to NIR, and because it is in the form of a polymer, it can exist stably. The intermediate layer, the polymer layer and the drug layer are all hydrophobic coatings, and the three layers have strong hydrophobic interactions and good bonding strength. The hydrophobic surface is more conducive to the adhesion of proteins and cells, and is conducive to the crawling of endothelial cells, thereby promoting endothelialization. After the drug layer is completely degraded, the rough hydrophobic polymer surface will be more conducive to the adsorption of proteins such as albumin and fibronectin, thereby promoting cell adhesion and endothelialization. After the drug layer is degraded, the internal polymer layer is exposed, and NIR can be used to excite the polymer layer to release NO, thereby promoting endothelialization. The present invention further optimizes the components of the polymer layer, and the structure of the polymer layer contains phosphorylcholine groups, which can improve the blood compatibility and biocompatibility of the stent and have an anti-coagulation function.

[0087] (2) The present invention provides a drug-eluting stent, which uses plasma etching technology to micro-etch the surface of the polymer layer on the surface of the stress concentration area during the contraction or expansion of the metal stent, forming a surface with a certain roughness, thereby causing the interface area between the polymer layer and the drug coating to be enlarged, thereby improving the bonding strength between the two. The rough surface contributes more mechanical cross-linking, thereby improving the interface shear strength between the polymer layer and the drug layer, further improving the bonding strength between the two, and achieving the effect of preventing the polymer drug coating on the surface of the stress concentration area during the contraction or expansion of the drug stent from cracking, peeling or falling off.

[0088] The present invention further optimizes the plasma etching method, by using fluorine-containing gas for plasma etching, introducing fluorine-containing groups on the surface of the polymer layer on the surface of the stress concentration area, and enhancing the surface hydrophobicity, so that the polymer layer at these positions and the hydrophobic polymer drug coating will have a stronger hydrophobic interaction, thereby having a stronger bonding force to cope with the mechanical stripping force caused by repeated stretching and compression of the area, thereby preventing the drug layer from cracking, peeling or falling off during the contraction or expansion of the drug stent.

[0089] In order to improve the bonding strength between the intermediate layer and the polymer layer, the present invention performs plasma treatment on the intermediate layer, performs inert gas treatment on the entire surface of the intermediate layer, introduces free radicals, and thus provides more active sites for subsequent polymerization reactions. The polymer layer solution is then sprayed on the surface of the intermediate layer, polymerization is initiated by ultraviolet light, and in-situ polymerization is performed to form a polymer layer.

[0090] (3) The present invention provides a stent with stable drug release. By etching the drug layer with inert gas, blank or low-dose areas exist in the drug coating in the microscopic area. Due to this concentration difference, the drug can be released in a relatively smooth straight line, that is, concentration balance, thereby improving the overall utilization rate of the drug. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 is the structural diagram of the network copolymer;

[0092] Figure 2 The schematic diagram of compound g releasing NO under NIR excitation;

[0093] Figure 3 is the synthetic route of compound g;

[0094] Figure 4 This is a graph showing the cytotoxicity test results for compound g;

[0095] Figure 5 This is a graph of NO release concentration of the drug stent in Example 2-6;

[0096] Figure 6 It is a structural diagram of the drug-eluting stent, where 1 is the intersection of the stent beams;

[0097] Figure 7 It is a cross-sectional view of the stress concentration area of ​​the stent, wherein 2 is the stent body, 3 is the intermediate layer, 4 is the polymer layer, and 5 is the drug layer;

[0098] Figure 8 is a schematic diagram of the surface pattern after etching, wherein the light-colored area 41 is the etched area;

[0099] Fig. 9It is a cross-sectional view of the stress concentration area of ​​the stent, wherein 2 is the stent body, 3 is the intermediate layer, 4 is the polymer layer, and 5 is the drug layer;

[0100] Fig.10 is a schematic diagram of the surface pattern after etching, wherein the light-colored area 41 is the etched area;

[0101] Fig.11 It is a cross-sectional view of the stress concentration area of ​​the stent, wherein 2 is the stent body, 3 is the intermediate layer, 4 is the polymer layer, and 5 is the drug layer;

[0102] Fig.12 is a schematic diagram of the surface pattern after etching, wherein the light-colored area 41 is the etched area;

[0103] Fig.13 The stent morphology of Example 8-15 drug-eluting stent before and after simulated body fluid flushing;

[0104] Fig.14 The stent morphology of Example 8-15 after drug stent release and simulated body fluid flushing;

[0105] Fig.15 The drug release curves of the drug stents of Examples 8 and 16-18 are shown. DETAILED DESCRIPTION

[0106] To further illustrate the technical means and effects of the present invention, the present invention is further described below in conjunction with the embodiments and drawings. It should be understood that the specific implementation methods described herein are only used to explain the present invention, rather than to limit the present invention.

[0107] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0108] Example 1

[0109] This example prepares a compound with NIR-responsive NO controllable release performance. The synthesis route is as follows: Figure 3 As shown, the following steps are included:

[0110] (1) Compound a and di-tert-butyl dicarbonate (Boc 2 O) was added in a molar ratio of 1:(1.05-1.30), 1,4-dioxane was used as solvent, the reaction was carried out at 90-110°C for 8-10 h, and the reaction was cooled with ice water after completion of the reaction. Compound b was obtained after purification.

[0111] (2) Compound b first reacts with N 2Under the protection of , dispersed in anhydrous tetrahydrofuran (THF), sodium hydride (NaH) (60 wt%, dispersed in mineral oil) was added in batches under ice-water bath conditions, and after reacting for 20 min, iodomethane (MeI) was added, and stirring was continued for 30-60 min. The molar ratio of compound b, NaH and MeI was 1: (1.1-1.3): (2.2-2.6). After purification, it was stirred evenly with benzaldehyde (PhCHO), potassium hydroxide (KOH) and ethanol (EtOH), and nitromethane (MeNO 2 ), purified product, PhCHO, KOH, EtOH and MeNO 2 The molar ratio is 1: (1.0~1.1): (3.0~3.2): (1.0~1.1): (15.0~16.0). The reaction was carried out at room temperature for 10~12 h. After the reaction was completed, the product was purified. The product was dissolved in dichloromethane (DCM), and an excess of trifluoroacetic acid (TFA) was added. The reaction was carried out at room temperature for 1~2 h, cooled to 0°C, and the reaction was quenched with a saturated sodium bicarbonate solution. Compound c was obtained after purification.

[0112] (3) After compound c and compound d were completely dissolved in n-butanol at 110°C, ammonium acetate (NH 4 OAc), and the reaction was continued at this temperature for 8-10 h. After purification, compound e was obtained. 4 OAc was added in a molar ratio of 1: (2.0~2.2): (15.0~16.0).

[0113] (4) Using DCM as solvent, compound e, triethylamine (Et 3 N) and boron trifluoride etherate complex (BF 3 OE 2 ) half of the total amount, stirred at room temperature for 2-3 h, and then added the other half of BF 3 OE 2 The reaction was continued at room temperature for 20 to 24 hours. 3 N and BF 3 OE 2 The materials are added in a molar ratio of 1: (100-110): (300-320). After the reaction is completed, compound f can be obtained through purification.

[0114] (5) Product f was dissolved in a mixed solution of anhydrous glacial acetic acid (AcOH), THF, and DCM (the volume ratio of the three was 0.51:1:1), cooled to 0°C, and NaNO 2 , product f and NaNO 2The materials are added in a molar ratio of 1:(5.0~5.4), and then the reaction is continued with stirring for 1~2 hours. After washing and purification, compound g is obtained.

[0115] The obtained compound g was subjected to NMR analysis, and the results were as follows:

[0116] 1 H NMR (500 MHz, CDCl 3 ) δ 8.15-8.10 (m, 2H), 8.06 (dt, J = 8.3, 6.0Hz, 6H), 7.50-7.39 (m, 5H), 7.37 (t, J = 7.3 Hz, 1H), 7.18 (d, J = 3.6 Hz, 1H), 7.10-7.05 (m, 3H), 6.93 (s, 1H), 6.63 (t, J = 8.0 Hz, 2H), 6.10 (s, 1H), 5.45-5.30 (m, 2H), 4.75 (t, J = 2.2 Hz, 2H), 2.93-2.82 (m, 3H); 13 C NMR (125MHz, CDCl 3 ) δ 164.6, 160.8, 160.4, 142.5, 136.8, 136.4, 133.5, 132.5, 131.8, 131.6, 131.6, 130.2, 129.2, 128.9 , 128.7, 128.6, 128.3, 127.9, 127.5, 125.4, 124.0, 120.7, 118.2, 115.2, 114.4, 104.9, 70.2, 32.5; 11 B NMR (161 MHz, CDCl 3 ) δ 1.32; 19 F NMR (471MHz, CDCl 3 )δ -132.09.

[0117] Elemental Analysis:

[0118] Calculated values ​​are: C, 70.72%; H, 4.62%; B, 1.77%; F, 6.21%; N, 11.45%; O, 5.23%.

[0119] The test values ​​are: C, 70.65%; H, 4.65%; B, 1.79%; F, 6.16%; N, 11.39%; O, 5.36%.

[0120] The cytotoxicity test of compound g prepared in this example was carried out using L929 cells. The concentrations of compound g were 0.025 mg / mL, 0.05 mg / mL, 0.1 mg / mL and 0.2 mg / mL, respectively. The PBS group was used as a negative control. The cell viability after treatment was as follows: Figure 4 shown.

[0121] Example 2

[0122] This embodiment prepares a drug-eluting stent, comprising the following steps:

[0123] (1) Cleaning the bracket and preparing the silane solution

[0124] The nickel-titanium stent was ultrasonically cleaned in acetone for 3 min, then ultrasonically cleaned in anhydrous ethanol for 8 min, and then taken out and dried naturally.

[0125] Vinyltrimethoxysilane was dissolved in ethanol, the pH was adjusted to 6.0 and then vigorously stirred for 30 min to prepare a 1.0 wt % vinyltrimethoxysilane isopropanol solution.

[0126] (2) Coating the intermediate layer on the stent surface

[0127] The cleaned nickel-titanium stent was immersed in a silane solution for 60 min, washed, and dried at 55°C for 40 min. A layer of polyparaxylene C film with a thickness of 1 μm was deposited on the surface of the stent using chemical vapor deposition.

[0128] (3) Formation of a polymer layer on the surface of the intermediate layer

[0129] Using DCM as solvent, compound g, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide were mixed in a molar ratio of 2:2.5:10:0.35, and after being completely dissolved in DCM, benzophenone was added, and the amount of initiator benzophenone was 0.5% of the total mass of the monomers to form a homogeneous solution, i.e., a polymer layer solution, and the solid content of the solution was 11 wt%. Finally, it was filtered once using a filter membrane with a pore size of 1 μm.

[0130] The above solution was sprayed onto the surface of the stent obtained in step (2) and cured using ultraviolet light (curing conditions: UV light density 40 mW / cm 2 , curing for 45 min), the polymer layer thickness was 6 μm.

[0131] Example 3

[0132] This embodiment prepares a drug-eluting stent, comprising the following steps:

[0133] (1) Cleaning the bracket and preparing the silane solution

[0134] The nickel-titanium stent was ultrasonically cleaned in acetone for 2 min, then ultrasonically cleaned in anhydrous ethanol for 10 min, and then taken out and dried naturally.

[0135] γ-methacryloxypropyltrimethoxysilane was dissolved in anhydrous ethanol, and the pH was adjusted to 3.0 and then vigorously stirred for 120 min to prepare a 3.0 wt% γ-methacryloxypropyltrimethoxysilane ethanol solution.

[0136] (2) Coating the intermediate layer on the stent surface

[0137] The cleaned nickel-titanium stent was immersed in a silane solution for 30 min, washed, and dried at 65°C for 30 min. A layer of polyparaxylene C film with a thickness of 0.5 μm was deposited on the surface of the stent using chemical vapor deposition.

[0138] (3) Formation of a polymer layer on the surface of the intermediate layer

[0139] Using DCM as solvent, compound g, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide were mixed in a molar ratio of 6:10:20:1, and after being completely dissolved in DCM, benzophenone was added. The amount of initiator benzophenone was 1% of the total mass of the monomers to form a homogeneous solution with a solid content of 20 wt%. Finally, it was filtered once using a filter membrane with a pore size of 0.45 μm.

[0140] The above solution was sprayed onto the surface of the stent obtained in step (2) and cured using ultraviolet light (curing conditions: UV light density 30 mW / cm 2 , cured for 60 min) with a thickness of 10 μm.

[0141] Example 4

[0142] This embodiment prepares a drug-eluting stent, comprising the following steps:

[0143] (1) Cleaning the bracket and preparing the silane solution

[0144] The nickel-titanium stent was ultrasonically cleaned in acetone for 5 min, then ultrasonically cleaned in anhydrous ethanol for 5 min, and then taken out and dried naturally.

[0145] 3-Glycidyloxypropyltrimethoxysilane was dissolved in propanol, and the pH was adjusted to 10 and then vigorously stirred for 30 minutes to prepare a 1.0 wt% propanol solution of 3-glycidyloxypropyltrimethoxysilane.

[0146] (2) Coating the intermediate layer on the stent surface

[0147] The cleaned nickel-titanium stent was immersed in a silane solution for 120 min, washed, and dried at 40°C for 120 min. A layer of polyparaxylene C film with a thickness of 2 μm was deposited on the surface of the stent using chemical vapor deposition.

[0148] (3) Formation of a polymer layer on the surface of the intermediate layer

[0149] Using DCM as solvent, compound g, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide were mixed in a molar ratio of 1:2:1:0.1, and benzophenone was added after being completely dissolved in DCM. The amount of initiator benzophenone was 0.1% of the total mass of the monomers to form a homogeneous solution with a solid content of 3 wt%. Finally, it was filtered once using a filter membrane with a pore size of 0.22 μm.

[0150] The above solution was sprayed on the surface of the stent and cured using ultraviolet light (curing conditions: UV light density 50 mW / cm 2 , curing for 30 min) with a thickness of 3 μm.

[0151] Example 5

[0152] This example prepares a drug-eluting stent, which is different from Example 2 only in that compound g, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide are mixed in a molar ratio of 8:2.5:10:0.05.

[0153] Example 6

[0154] This example prepares a drug-eluting stent, which is different from Example 2 only in that compound g, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide are mixed at a molar ratio of 0.5:10:20:1.

[0155] Results and Discussion

[0156] The drug stent prepared in Example 2-6 was illuminated in the dark using a near-infrared light source (808 nm, 40 mW / cm 2 ) were irradiated for 180 min, and the concentration of nitric oxide was measured using a Griess kit at 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 80 min, 100 min, 120 min and 180 min, respectively. The release medium was a pH 7.4 phosphate buffer containing 0.4% sodium dodecyl sulfate. The results are shown in Figure 5 shown.

[0157] As shown in the figure, in Examples 2, 3, and 4, the NO release of the stents of Examples 2-4 under near-infrared light showed a relatively stable increase with time, and the total NO release under 3 h of continuous irradiation could reach 131.03, 112.71, and 165.45 μM, respectively. It can be seen that the present invention can achieve the regulation of NO release rate and total release by controlling the thickness of the stent polymer layer and the ratio of the polymer solution raw materials, thereby preventing excessive NO from causing damage in the body; on the contrary, there was a burst release in Example 5, which almost reached the peak at 30 min, and then only a small amount of NO was released, which may be due to the fact that compound g did not fully participate in the copolymerization reaction; and the NO release amount of Example 6 was too low, and the NO concentration only reached 28.33 μM after continuous illumination for 3 h, which may be due to the fact that too little compound g was added, resulting in a small content of compound g units in the polymer layer and a low total amount of NO that can be released.

[0158] Samples prepared in Example 2-6 (the material and treatment method are consistent with those of the bracket) were tested for water contact angle using a contact angle meter. The results are shown in Table 1.

[0159] Table 1

[0160]

[0161] As shown in Table 1, the scaffold polymer layer exhibits different hydrophobic properties. This is because in the structural composition of the copolymer, the 2-methacryloyloxyethyl phosphorylcholine (MPC) unit is hydrophilic, and the compound g unit and the n-butyl methacrylate unit are both hydrophobic. The higher the proportion of the MPC unit, the lower the contact angle of the obtained polymer layer.

[0162] Since the residual solvent may be removed by heating after the stent is sprayed with the drug layer, the stent carrier needs to have low thermal sensitivity. By testing the thermal stability of the stents of Examples 2, 3, and 4 under nitrogen protection, it was found that Examples 2-4 all had quality fluctuations around 162.3°C, indicating that the polymer layer of the present invention can remain thermally stable at this temperature.

[0163] The samples were placed in a phosphate buffer solution at pH 7.4 (containing 0.4% sodium dodecyl sulfate, 37°C). Samples were taken out regularly to detect the NO release and sample weight changes. After the test, the samples were continued to be placed in the buffer solution. The number of samples was 4 pcs, and the results were averaged. The results are shown in Table 2.

[0164] Table 2

[0165]

[0166] As shown in Table 2, the stent samples of Examples 2-6 were placed in a phosphate buffer solution of pH 7.4 (containing 0.4% sodium dodecyl sulfate, 37°C), and the NO concentration in the buffer solution was regularly tested for 90 days, and no NO was detected, indicating that the polymer coating would not release any NO when not stimulated by NIR light; at the same time, the stent was weighed to determine its mass change and to determine whether the coating was degraded. The mass of the stents of Examples 2-4 and 6 did not change significantly, while the mass of the stent of Example 5 decreased by 0.13 mg, which may be due to the dissolution of the unreacted compound g monomer contained in the polymer layer.

[0167] Example 7

[0168] This embodiment prepares a drug-eluting stent, which is different from embodiment 2 in that the following steps are included before step (3):

[0169] The stent prepared in step (2) was treated with plasma (Ar as gas source) (plasma treatment parameters: 50 W, treatment for 45 min), and the polymer layer was immediately prepared according to step (3) after the treatment.

[0170] Example 8

[0171] This embodiment prepares a drug-eluting stent, which differs from embodiment 7 only in that after spraying the polymer layer solution in step (3), the surface of the stress concentration area (such as Figure 6 The cross section of the support beams shown in Figure 1 is patterned using sulfur hexafluoride plasma etching. Figure 7 As shown, the schematic diagram of the surface pattern after etching is as follows Figure 8 The etching pattern is circular depressions arranged in an array, with an etching depth of 300 nm and a cross-sectional area of ​​approximately 2000 μm 2 , the center distance between any two adjacent circular depressions is 100 μm.

[0172] The above process further includes the following steps:

[0173] (4) Preparation of drug coating solution: Dissolve 0.5 g paclitaxel and 2.5 g PLGA in 500 mL dichloromethane and stir for 120 min to dissolve to obtain a drug coating solution.

[0174] (5) Forming a drug layer on the surface of the polymer layer: The above solution is placed in a sprayer, and the polymer-coated stent obtained in step (3) is fixed on the support shaft under the nozzle. The support shaft is rotated so that the stent is sprayed with the drug coating solution in all directions, and the thickness of the drug coating on all parts of the stent is uniform; the solution inlet rate is 0.05 mL / min, the carrier gas is high-purity nitrogen, and the rotation speed is 2000 rpm. After the solvent evaporates and completely dries, a drug layer is formed, and the drug coating thickness is 8 μm.

[0175] Example 9

[0176] This embodiment prepares a drug-eluting stent, which differs from embodiment 7 only in that after spraying the polymer layer solution in step (3), the surface of the stress concentration area (such as Figure 6 The cross section of the support beams shown in 1) is patterned using tetrafluoromethane plasma etching. The cross-sectional view of the stress concentration area of ​​the support is shown in Fig. 9 As shown, the schematic diagram of the surface pattern after etching is as follows Fig.10 The etching method is parallel first grooves and parallel second grooves, the first grooves and the second grooves are perpendicular to each other, the etching depth is 300 nm, the width of the first groove and the second groove are both 50 μm, and the spacing between adjacent first grooves and adjacent second grooves is 50 μm.

[0177] The above process further includes the following steps:

[0178] (4) Preparation of drug coating solution: Dissolve 0.6 g rapamycin and 1.8 g PLA in 500 mL dichloromethane and stir for 120 min to dissolve to obtain a drug coating solution.

[0179] (5) Forming a drug layer on the surface of the polymer layer: The drug-containing PLA solution is applied to the surface of the polymer layer by spraying. After the solvent evaporates and dries completely, a drug layer with a thickness of 5 μm is formed.

[0180] Example 10

[0181] This embodiment prepares a drug-eluting stent, which differs from embodiment 7 only in that after spraying the polymer layer solution in step (3), the surface of the stress concentration area (such as Figure 6 The cross section of the support beam shown in 1) is patterned using tetrafluoroethylene plasma etching. The cross-sectional view of the stress concentration area of ​​the support is shown in Fig.11 As shown, the schematic diagram of the surface pattern after etching is as follows Fig.12The etching method is parallel first grooves and parallel second grooves. The first grooves and the second grooves are perpendicular to each other. The etching depth is 300 nm. The width of the first groove and the second groove is 50 μm. The spacing between adjacent first grooves and adjacent second grooves is 50 μm. There is a circular depression in the closed area surrounded by two adjacent first grooves and two adjacent second grooves. The etching depth of the circular depression is 300 nm and the cross-sectional area is about 1300 μm. 2 .

[0182] The above process further includes the following steps:

[0183] (4) Preparation of drug coating solution: Dissolve 0.3 g everolimus and 3.0 g PGA in 500 mL dichloromethane and stir for 120 min to dissolve to obtain a drug coating solution.

[0184] (5) Forming a drug layer on the surface of the polymer layer: The drug-containing PGA solution is applied to the surface of the polymer layer by spraying. After the solvent evaporates and dries completely, a drug layer with a thickness of 10 μm is formed.

[0185] Embodiment 11

[0186] This example prepares a drug stent, which is different from Example 8 only in that the etching depth of the circular depression is 50 nm.

[0187] Example 12

[0188] This example prepares a drug stent, which is different from Example 8 only in that the etching depth of the circular depression is 1500 nm.

[0189] Embodiment 13

[0190] This embodiment prepares a drug-eluting stent, which is different from Embodiment 8 only in that after spraying the polymer layer solution in step (3), no treatment is performed on the surface of the stress concentration area during the contraction or expansion process of the stent.

[0191] Embodiment 14

[0192] This embodiment prepares a drug-eluting stent, which is different from Embodiment 9 only in that after spraying the polymer layer solution in step (3), no treatment is performed on the surface of the stress concentration area during the contraction or expansion process of the stent.

[0193] Embodiment 15

[0194] This embodiment prepares a drug-eluting stent, which is different from Embodiment 10 only in that after spraying the polymer layer solution in step (3), no treatment is performed on the surface of the stress concentration area during the contraction or expansion process of the stent.

[0195] Results and Discussion

[0196] Group 1: The stents prepared in Examples 8-15 were circulated in simulated body fluid (37°C) for 30 days, and the drug coating morphology was observed to test the integrity of the stent drug coating. The stent morphology photos are shown in Fig.13 The drug coating morphology of the stent in Group 1 was observed, and it was found that no obvious coating shedding was found in Examples 8-15 before and after flushing.

[0197] Group 2: The stents prepared in Examples 8-15 were released 30 times in simulated body fluid (37°C) into a blood vessel model with a nominal outer diameter, and then washed for 30 days. The morphology of the stent drug coating was observed and the integrity of the stent drug coating was tested. The stent morphology photos are shown in Fig.14 As shown. No cracks or shedding were found in the coating of the stents of Examples 8-10 and 12, and no cracks or damage were found in the coating of the stents of Examples 13-15 in stress concentration areas such as intersections. After the stent was subjected to cyclic flushing for 30 days, it was found that the coating of the stents of Examples 8-10 and 12 was still not found to fall off, while the coating of the stents of Examples 13-15 was found to be damaged to varying degrees, or even fell off, in stress concentration areas such as intersections. It can be seen that in the process of simulating actual use of the stent, the multiple releases caused by transportation and position adjustment and the long-term flushing of blood jointly caused the coating in the stress concentration area of ​​the stent to break and fall off. Since the etching depth of Example 11 is only 50 nm, the integrity of the stent drug coating is close to that of Examples 13-15. Although Example 12 shows relatively excellent drug coating integrity, due to the etching depth of 1500 nm, the residual amount of dichloromethane is significantly higher under the same preparation process, and additional steps are required to reduce the residual amount of dichloromethane.

[0198] Example 16

[0199] This embodiment prepares a drug-eluting stent. The only difference from embodiment 8 is that after step (5), an inert gas (Ar as a gas source) plasma etching patterning treatment is used. The etching pattern is referred to as Figure 8 The etching method is circular depressions arranged in an array, with an etching depth of 2500 nm and a cross-sectional area of ​​about 2000 μm 2 , the center distance between any two adjacent circular depressions is 100 μm.

[0200] Embodiment 17

[0201] This embodiment prepares a drug stent, which differs from the embodiment 16 only in that the etching depth is 4000 nm and the cross-sectional area is about 3200 μm 2 , the center distance between any two adjacent circular depressions is 80 μm.

[0202] Embodiment 18

[0203] This embodiment prepares a drug stent, which differs from the embodiment 16 only in that the etching depth is 6000 nm and the cross-sectional area is about 4800 μm 2 , the center distance between any two adjacent circular depressions is 50 μm.

[0204] Results and Discussion

[0205] The etching depths of Examples 16-18 were 2500 nm, 4000 nm, and 6000 nm, respectively, and the drug content ratios of the etched portion and the unetched portion in a corresponding microscopic region were 90%, 80%, and 70%. The drug release curve for 120 days was tested (drug release medium: pH 7.4 phosphate buffer containing 0.4% sodium dodecyl sulfate). Fig.15 As shown, the release rate of Example 8 without etching is significantly higher than that of Examples 16-18 with surface etching, and the cumulative drug release reaches about 85% at about 35 days, and exceeds 90% at about 40 days; the drug release rate of Examples 16-18 is slower in the early stage, and there is still continuous drug release in the later stage, and the cumulative drug release reaches about 85% at about 60 days, and exceeds 90% at about 90 days.

[0206] Comparative Example 1

[0207] This comparative example prepares a drug-eluting stent, comprising the following steps:

[0208] (1) Cleaning the bracket and preparing the silane solution according to step (1) of Example 2;

[0209] (2) coating an intermediate layer on the surface of the stent according to step (2) of Example 2;

[0210] (3) According to steps (4) and (5) of Example 8, a drug layer is formed on the surface of the stent. The thickness of the drug coating is 8 μm.

[0211] Comparative Example 2

[0212] This comparative example prepares a drug-eluting stent, comprising the following steps:

[0213] (1) Cleaning the bracket and preparing the silane solution according to step (1) of Example 2;

[0214] (2) coating an intermediate layer on the surface of the stent according to step (2) of Example 2;

[0215] (3) According to steps (4) and (5) of Example 9, a drug layer is formed on the surface of the stent. The thickness of the drug coating is 5 μm.

[0216] Comparative Example 3

[0217] This comparative example prepares a drug-eluting stent, comprising the following steps:

[0218] (1) Cleaning the bracket and preparing the silane solution according to step (1) of Example 2;

[0219] (2) coating an intermediate layer on the surface of the stent according to step (2) of Example 2;

[0220] (3) According to steps (4) and (5) of Example 10, a drug layer is formed on the surface of the stent. The thickness of the drug coating is 10 μm.

[0221] Results and Discussion

[0222] Comparison between comparative examples 1, 2, and 3 and examples 8, 9, and 10 shows that since examples 8 to 10 all contain a polymer layer, while comparative examples 1 to 3 do not contain a polymer layer, the incidence of late lumen loss in the stents of examples 8 to 10 9 months after implantation is significantly reduced.

[0223] Comparison between the tests of Examples 16, 17, and 18 and Examples 8, 9, and 10 shows that the incidence of restenosis is significantly reduced 9 months after stent implantation.

[0224] In summary, the present invention provides a drug coating and drug stent capable of in-situ controllable release of nitric oxide in vivo, wherein a layer of polymer is prepared on the surface of the intermediate layer, the polymer layer has a near-infrared light-responsive nitric oxide controllable release performance, and the drug layer is patterned to stably release the drug, thereby optimizing the anti-proliferation and endothelial remodeling performance of the drug stent. In addition, the present invention modifies the interface of the stent drug coating, so that the drug coating is not easy to fall off and lose, and the stent has good biocompatibility and safety.

[0225] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A drug coating for in situ controlled release of nitric oxide in vivo, characterized in that: The drug coating comprises an intermediate layer, a polymer layer and a drug layer; Wherein, the polymer layer is located between the intermediate layer and the drug layer, the intermediate layer contains polyparaxylene, and the polymer layer contains a mesh copolymer capable of releasing nitric oxide; The preparation method of the network copolymer comprises: using dichloromethane as a solvent, adding a compound as shown in formula I, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide in a molar ratio of (1-6):(2-10):(1-20):(0.1-1), and after the mixture is completely dissolved in dichloromethane, adding benzophenone, wherein the amount of the initiator benzophenone is 0.1%-1% of the total mass of the compound as shown in formula I, 2-methacryloyloxyethyl phosphorylcholine, n-butyl methacrylate and N,N-methylenebisacrylamide, after forming a homogeneous solution, filtering with a filter membrane, wherein the solid content of the solution is 3 wt%-20 wt%, and using ultraviolet light to initiate polymerization of each monomer to obtain the network copolymer; Formula I is shown below: Formula I The drug layer contains a polymer and a drug, wherein the polymer includes any one of PLA, PGA, PCL, PLGA, PCL-b-PDLLA, PCL-PDLLA-PGA or PCL-PGA-PDLLA or a combination of at least two thereof, and the drug includes one of anti-proliferative drugs, anti-coagulant drugs, anti-thrombotic drugs, anti-tumor drugs, anti-inflammatory drugs or gene therapy drugs or a combination of at least two thereof.

2. The drug coating according to claim 1, characterized in that The thickness of the intermediate layer is 0.5-2 μm, the thickness of the polymer layer is 3-10 μm, and the thickness of the drug layer is 5-10 μm; The polyparaxylene includes any one of polyparaxylene C, polyparaxylene N, polyparaxylene D, polyparaxylene F or polyparaxylene HT, or a combination of at least two thereof; The weight average molecular weight of the polyparaxylene is 500-5000 kDa; The network copolymer has the ability of controlled release of nitric oxide in response to near infrared light.

3. A drug-eluting stent, characterized in that: The surface of the drug stent is coated with the drug coating according to claim 1 or 2, and the drug stent comprises, from the inside to the outside, a stent body (2), an intermediate layer (3), a polymer layer (4) and a drug layer (5).

4. A method for preparing a drug-eluting stent as claimed in claim 3, characterized in that: The method for preparing the drug stent comprises sequentially preparing an intermediate layer (3), a polymer layer (4) and a drug layer (5) on the surface of a stent body (2).

5. The method for preparing a drug-eluting stent according to claim 4, characterized in that: The preparation method of the drug stent specifically comprises the following steps: S1. Immerse the stent in a silane solution, wash and dry, and deposit polyparaxylene on the surface of the stent; S2. The stent prepared in step S1 is treated with plasma; S3. The raw materials for preparing the polymer layer are mixed uniformly to obtain a polymer layer solution; S4. Spraying the polymer layer solution onto the surface of the stent and curing it with ultraviolet light; S5. The raw materials for preparing the drug layer are mixed uniformly to obtain a drug layer solution; S6. Apply the drug layer solution to the surface of the stent prepared in step S4, and obtain the drug stent after drying.

6. The method for preparing a drug-eluting stent according to claim 5, characterized in that: The silane in the silane solution in step S1 includes any one of γ-methacryloxypropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane, bis-[γ-(triethoxysilyl)propyl]-tetrasulfide, 1,2-bis(triethoxysilyl)ethane or bis[3-(trimethoxysilyl)propyl]amine, or a combination of at least two thereof; The solvent in the silane solution in step S1 is any one of methanol, ethanol, propanol, isopropanol or ultrapure water, or a combination of at least two thereof; The concentration of the silane solution in step S1 is 1-3 wt %; The pH value of the silane solution in step S1 is 3-10; The gas source for the plasma treatment in step S2 is an inert gas, and the inert gas includes helium and / or argon.

7. The method for preparing a drug-eluting stent according to claim 5, characterized in that: Step S4 comprises: spraying the polymer layer solution on the surface of the stent, curing with ultraviolet light, and plasma etching and patterning the surface of the stress concentration area during the contraction and / or expansion process of the prepared stent; The stress concentration area during the contraction and / or expansion of the stent includes the intersection of the stent beams of the drug stent; The gas source of the plasma etching is a fluorine-containing gas, and the fluorine-containing gas includes any one of sulfur hexafluoride, tetrafluoromethane, tetrafluoroethylene, hexafluoroethane, hexafluoropropylene or octafluorocyclobutane, or a combination of at least two thereof.

8. The method for preparing a drug-eluting stent according to claim 5, characterized in that: Step S6 comprises: coating the drug layer solution onto the surface of the stent prepared in step S4, drying, and performing plasma etching patterning on the surface of the drug layer to obtain the drug stent; The gas source of the plasma etching is an inert gas; After the plasma etching patterning, the drug content ratio between the etched area and the unetched area is (0.7-0.9):

1.

9. The method for preparing the drug stent according to claim 7 or 8, characterized in that: The plasma etching patterning in step S4 and the plasma etching patterning in step S6 are each independently any one of the following patterning methods (I), (II) or (III): (I) at least two polygonal depressions or circular depressions arranged in an array; (II) at least two parallel first grooves and at least two parallel second grooves, the first grooves and the second grooves intersecting each other; (III) Based on the patterning method (II), in the closed area enclosed by any two adjacent first grooves and any two adjacent second grooves, there is a polygonal depression or a circular depression as described in the patterning method (I); The etching depths of the polygonal depression, the circular depression, the first groove and the second groove are each independently 100 to 6000 nm; The cross-sectional areas of the polygonal depression and the circular depression are independently 100 to 5000 μm 2 ; The center distance between any two adjacent polygonal depressions and any two adjacent circular depressions is independently 50-200 μm; The widths of the first groove and the second groove are independently 10 to 100 μm; The distance between any two adjacent first grooves and any two adjacent second grooves is independently 10-100 μm.

10. A stent for stable drug release, characterized in that: The stent with stable drug release is prepared using the preparation method of the drug stent according to any one of claims 4 to 9.

11. A method for balancing drug concentration, characterized in that: The method for balancing drug concentration comprises delivering the drug using the drug stent of claim 3 or the stent for stable drug release of claim 10.

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