Functional coating, intravascular stent and preparation method and application thereof

Abstract

The invention discloses a functional coating, an intravascular stent and a preparation method and application of the intravascular stent. The functional coating comprises an endothelialization promoting active substance and an anti-proliferation drug; the endothelialization promoting active substance comprises at least one of polypeptide containing an RGD sequence, polypeptide containing a YIGSR sequence, polypeptide containing an REDV sequence, a beta-polypeptide polymer or a beta-polypeptide-polyester block copolymer. The functional coating disclosed by the invention can be used for surface functional modification of interventional medical devices, can selectively promote adhesion and proliferation of vascular endothelial cells at an implantation part, realizes rapid endothelialization, and can controllably release an anti-proliferation drug to inhibit excessive proliferation of vascular smooth muscle cells, so that the vascular endothelial cells are prevented from being damaged. Therefore, the risks of restenosis and advanced thrombus are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of biomedical device technology, specifically to a functional coating, a vascular stent, its preparation method, and its application. Background Technology

[0002] Vascular stents are widely used in the treatment of cardiovascular diseases, especially in percutaneous coronary intervention (PCI), to effectively dilate narrowed or blocked blood vessels and restore blood flow. Early stents were bare-metal stents, primarily made of 316L stainless steel or cobalt-chromium alloy. Compared to simple balloon angioplasty, stent implantation effectively reduces vascular elastic recoil and maintains longer-lasting luminal patency. However, the main drawback of bare-metal stents is the late-stage lumen loss and in-stent restenosis caused by postoperative intimal hyperplasia, with a relatively high restenosis rate. Therefore, they have been gradually replaced by drug-eluting stents. Drug-eluting stents typically use 316L stainless steel or cobalt-chromium alloy as a base, employing non-degradable polymers as drug carriers, loaded with anti-proliferative drugs such as rapamycin or paclitaxel. By inhibiting the migration and proliferation of vascular smooth muscle cells, they significantly reduce the incidence of in-stent restenosis. However, while these drugs inhibit smooth muscle cells, they inevitably delay the endothelial repair process. Combined with the potential for chronic inflammatory reactions caused by the non-degradable polymer coating, this increases the risk of late-stage in-stent thrombosis.

[0003] Functional interface modification strategies, which accelerate scaffold endothelialization by immobilizing bioactive molecules, have become an important direction for improving biocompatibility. For example, CD34 antibody-functionalized scaffolds can accelerate endothelial coverage of the scaffold surface by capturing endothelial progenitor cells in the blood; while coating the scaffold surface with a peptide coating containing the arginine-glycine-aspartic acid (RGD) sequence can directly promote the adhesion of vascular endothelial cells. However, the above-mentioned strategies for promoting endothelialization generally lack the ability to selectively inhibit smooth muscle cells.

[0004] Endothelial cell-specific peptides offer a better solution to address the lack of selectivity. However, to date, only a few proteins or peptides have been shown to possess endothelial cell selectivity, with the tyrosine-isoleucine-glycine-serine-arginine (YIGSR) and arginine-glutamic acid-aspartic acid-valine (REDV) sequences derived from the extracellular matrix being the most widely used. These peptides promote endothelial cell adhesion and proliferation by specifically binding to integrin receptors on the surface of endothelial cells. However, their clinical application remains limited by inherent constraints such as poor enzymatic stability, high synthesis costs, and difficulties in large-scale production.

[0005] To this end, Zhou Ruiyi and his team pioneered a new approach in the search for endothelial cell-selective biomaterials. They synthesized a series of β-peptide polymers via ring-opening polymerization of β-lactams and modulated the adhesion behavior of endothelial cells (ECs) and smooth muscle cells (SMCs) by adjusting the ratio of cationic to hydrophobic amino acid residues in the β-peptide polymers. The optimal β-peptide polymer was NM. 40 CH 60 It exhibits higher selectivity for ECs and SMCs in cell adhesion, proliferation, and migration than classic endothelial cell-selective peptides. The molecular mechanism of its selectivity is closely related to the interfacial competitive adsorption of serum proteins. Compared to REDV and RGD surfaces, NM... 40 CH 60 The surface is enriched with a higher density and uniform distribution of bovine serum albumin (BSA). BSA competitively weakens the binding sites of adhesion-promoting proteins such as fibronectin and hyalin through steric hindrance. Due to NM... 40 CH 60 The surface can accommodate more EC membrane proteins and adhesion-related molecules. The inhibitory effect of BSA has a weak effect on EC adhesion, but significantly hinders the adhesion of SMCs, thus endowing the material with excellent bicellular selectivity. Reference: Zhou, R., Wu, Y., Chen, K., Zhang, D., Chen, Q., Zhang, D., … Zhu, Y. (2022). APolymeric Strategy Empowering Vascular Cell Selectivity and Potential Application Superior to Extracellular Matrix Peptides. Advanced Materials, 34(42). https: / / doi.org / 10.1002 / adma.202200464. Furthermore, Chinese patent application CN105816921A discloses a biomimetic vascular stent, comprising a bare stent for support, a polymer coating containing phosphorylcholine (PC) groups, a polymer coating containing REDV peptides or other endothelial (progenitor) cell recognition molecules, and a drug-loaded biodegradable polymer coating. Specifically, it discloses that when the stent is applied to the vascular lesion site, the drug-loaded biodegradable polymer coating on the outer surface of the stent gradually degrades, releasing the loaded drug to inhibit restenosis caused by smooth muscle proliferation within the blood vessel. The REDV sequence in the coating on the inner surface of the stent lumen can specifically promote the adhesion and growth of endothelial cells, accelerating the endothelialization process on the stent surface. However, while this technology employs a partitioned coating design on the inner and outer surfaces of the stent, achieving the function of promoting endothelial cell adhesion and growth on the inner surface, the outer surface only possesses a drug release function and lacks the biological function of actively promoting endothelial cell adhesion and growth. Simultaneously, the anti-proliferative drug released from the outer surface may diffuse and affect the endothelialization process in adjacent areas of the stent (including the edge of the inner surface), posing a risk of insufficient synergy between the inner and outer surface functions, thus limiting its practical application.

[0006] Therefore, there is an urgent need to develop a novel stent coating that maintains good stent support performance while possessing excellent biocompatibility, specifically promoting the adhesion and growth of vascular endothelial cells, and effectively inhibiting the excessive proliferation of vascular smooth muscle cells. This is of vital importance for preventing in-stent thrombosis and restenosis. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, the present invention aims to provide a functional coating that can be used in vascular interventional devices. This coating can selectively promote the adhesion and proliferation of vascular endothelial cells at the implantation site, achieving rapid endothelialization, while controllably releasing anti-proliferative drugs to inhibit excessive proliferation of vascular smooth muscle cells. This reduces the risk of thrombosis, effectively prevents restenosis, and improves treatment outcomes.

[0008] This invention is achieved through the following technical solution: In one aspect, a functional coating comprises an endothelialization-promoting active substance and an antiproliferative drug.

[0009] The endothelialization-promoting active substance includes at least one of the following: a polypeptide containing an RGD sequence, a polypeptide containing a YIGSR sequence, a polypeptide containing a REDV sequence, a β-peptide polymer, or a β-peptide-polyester block copolymer.

[0010] Furthermore, the endothelialization-promoting active substance is preferably a β-peptide-polyester block copolymer.

[0011] The β-peptide-polyester block copolymer is a block copolymer formed by the reaction of a β-peptide polymer with a degradable polyester having an NHS ester terminus to form amide bonds.

[0012] The monomer for the β-peptide polymer is β-amino acid-N-thiocarboxylic anhydride; the structural formula of the β-amino acid-N-thiocarboxylic anhydride is as follows: ; R1 and R2 are each independently selected from any one of hydrogen, phenyl, n-butyl, benzyloxycarbonylamino, and benzyloxycarbonyl; Furthermore, the β-amino acid-N-thiocarboxylic anhydride (β-NTA) is selected from at least one of N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride.

[0013] The structural formula of the N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride is as follows: NHCbz represents benzyloxycarbonylamino; The structural formula of the 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride is as follows: .

[0014] The β-amino acid-N-thiocarboxylic anhydride of the present invention can be obtained commercially or prepared by existing publicly disclosed preparation methods.

[0015] Further, the β-peptide polymer is a random copolymer obtained by polymerizing N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride. Preferably, the molar ratio of structural units derived from N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride to structural units derived from 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride in the β-peptide polymer is 1:(0.2-5).

[0016] Furthermore, the β-peptide polymer has a number-average molecular weight (Mn) of 3000-6000 and a molecular weight distribution (PDI) of 1.0-2.0. The number-average molecular weight and molecular weight distribution are determined by gel permeation chromatography (GPC).

[0017] This invention provides a method for preparing a β-peptide polymer, comprising the following steps: Weigh an appropriate amount of β-NTA and dissolve it in anhydrous N,N-dimethylformamide (DMF) to prepare a monomer solution with a concentration of 0.1-10 mol / L. Similarly, weigh an appropriate amount of 4-(tert-butyl)benzylamine (tBuBz-NH2) and dissolve it in DMF to prepare an initiator solution with a concentration of 0.01-1 mol / L. Add the monomer solution to the initiator solution, with a molar ratio of β-NTA monomer to initiator tBuBz-NH2 of (10-20):1. Stir the reaction at room temperature and monitor the reaction by thin-layer chromatography (TLC). After the reaction is complete, wash to obtain a white solid product; dissolve in double-distilled water, dialyze to remove small molecule impurities, filter through a 0.45 μm filter membrane, and freeze-dry to prepare the β-peptide polymer.

[0018] Further, the washing step is performed as follows: after the reaction is complete, tetrahydrofuran (THF) is added to rinse and the mixture is transferred to a centrifuge tube. Petroleum ether is added, and a white flocculent precipitate forms. The reaction solution is centrifuged, and the supernatant is discarded. Then, THF is added again to dissolve the precipitate, and petroleum ether is added. The mixture is centrifuged again, and the supernatant is discarded. This process is repeated 3-5 times to obtain a white solid. The white solid is dried in a vacuum drying oven for 1-3 days, then dissolved in trifluoroacetic acid. An equal volume of 33% hydrogen bromide-acetic acid solution (HBr·HOAc) is added, and the mixture is stirred at room temperature for 10-16 hours. The solvent is removed by rotary evaporation, methanol is added to dissolve the solid, and methyl tert-butyl ether pre-cooled at -20°C is added to precipitate the solid. The mixture is centrifuged, and the supernatant is discarded. This process is repeated 3-5 times, and the solid product is obtained by vacuum drying.

[0019] The biodegradable polyester with NHS ester ends described in this invention is a biodegradable polyester whose molecular chain ends are modified with active N-hydroxysuccinimide ester (NHS) groups; the biodegradable polyester includes, but is not limited to, polylactic acid (PLA), poly(lactic acid-glycolic acid) copolymer (PLGA), poly(ε-caprolactone) (PCL), poly(L-lactic acid-ε-caprolactone) copolymer (PLCL), and polyurethane (PU).

[0020] Further, the biodegradable polyester with NHS ester ends is selected from at least one of PLA-NHS, PLGA-NHS, PCL-NHS, PLCL-NHS, and PU-NHS. The PLA-NHS of this invention is a functionalized polylactic acid with active N-hydroxysuccinimide ester groups modified at the molecular chain ends; the PLGA-NHS is a functionalized poly(lactic acid-glycolic acid) copolymer with active N-hydroxysuccinimide ester groups modified at the molecular chain ends; the PCL-NHS is a functionalized poly(ε-caprolactone) with active N-hydroxysuccinimide ester groups modified at the molecular chain ends; the PLCL-NHS is a functionalized poly(L-lactic acid-ε-caprolactone) copolymer with active N-hydroxysuccinimide ester groups modified at the molecular chain ends; and the PU-NHS is a functionalized polyurethane with active N-hydroxysuccinimide ester groups modified at the molecular chain ends.

[0021] Furthermore, the intrinsic viscosity of the biodegradable polyester with NHS ester ends is 0.5-2.0 dL / g.

[0022] The biodegradable polyester with NHS ester ends described in this invention is commercially available.

[0023] Furthermore, the amino grafting rate of the β-peptide-polyester block copolymer is 0.3-0.7. The amino grafting rate is determined by the ortho-phthalaldehyde (OPA) method, as follows: (1) Preparation of o-phthalaldehyde (OPA) solution: Take 25 mL of 100 mmol / L sodium tetraborate, 2.5 mL of 20% SDS, 40 mg of o-phthalaldehyde, 1 mL of methanol, and 100 μL of β-mercaptoethanol into a 50 mL volumetric flask, and add ultrapure water to make up to 50 mL. Protect from light and prepare fresh before use.

[0024] (2) Sample preparation: Dissolve β-peptide polymer and β-peptide-polyester block copolymer in DMF to prepare 5 mmol / L solutions of β-peptide polymer (m) and β-peptide-polyester block copolymer (n) respectively and filter.

[0025] (3) Detection: Take 3 mL of OPA solution, add 0.7 mL of sample solution, shake, mix well, react for 2 min, transfer to a quartz cuvette, place in a UV spectrophotometer, and measure the absorbance of the mixture at 335 nm. Grafting rate (%) = (Am-An) / Am × 100%.

[0026] This invention provides a method for preparing a β-peptide-polyester block copolymer, comprising the following steps: S1. Weigh out the β-peptide polymer and dissolve it in a borate buffer solution with a pH of 7.4-8.5 to obtain a β-peptide polymer solution with a mass concentration of 2-20 mg / mL; S2. Weigh out the biodegradable polyester with NHS ester ends and dissolve it in N,N-dimethylformamide (DMF) to obtain a biodegradable polyester solution with a mass concentration of 0.1-0.5 g / mL; S3. Add the biodegradable polyester solution dropwise to the β-peptide polymer solution and react in a shaker at 4 ℃ for 4-12 h. After dialysis and filtration, the β-peptide-polyester block copolymer is obtained.

[0027] Furthermore, the antiproliferative drug is selected from at least one of rapamycin, paclitaxel, everolimus, zotamoxetine, and gemcitabine.

[0028] Secondly, the present invention provides the application of the aforementioned functional coating in the manufacture of vascular interventional medical devices or neurointerventional medical devices. The vascular interventional medical devices include vascular stents, balloon catheters, artificial blood vessels, etc.; the neurointerventional medical devices include nerve conduits, etc.

[0029] Thirdly, the present invention provides a vascular stent, comprising a bare metal stent and a coating applied to the surface of the stent; the coating is the functional coating described in the present invention.

[0030] Furthermore, the drug loading on the surface of the vascular stent is 2-4 μg / mm². 2 .

[0031] Fourthly, the present invention provides a method for preparing the aforementioned vascular stent, comprising the following steps: dissolving an antiproliferative drug and an endothelialization-promoting active substance in a solvent to prepare a coating solution; uniformly coating the coating solution onto the surface of a bare metal stent to form a functional coating.

[0032] Furthermore, the solvent includes, but is not limited to, dichloromethane, acetone, methanol, chloroform, or ethyl acetate.

[0033] Furthermore, the mass concentration of the drug in the coating solution is 3%-10%, and the mass concentration of the endothelialization-promoting active substance is 8%-20%.

[0034] The present invention has the following beneficial effects: The functional coating of this invention uses a β-peptide-polyester block copolymer, obtained by reacting a β-peptide polymer with a biodegradable polyester having an NHS ester terminus to form an amide bond, to load an anti-proliferative drug. Through the functional modification of the β-peptide polymer, the coating can specifically promote the adhesion and proliferation of vascular endothelial cells, achieving rapid endothelialization. At the same time, after hydration and swelling, the β-peptide-polyester block copolymer can form a stable diffusion channel, ensuring the continuous and stable release of the drug within the treatment time window, thereby effectively maintaining the local therapeutic concentration of the drug and achieving long-term inhibition of vascular smooth muscle cell proliferation. This reduces the risk of thrombosis, effectively prevents restenosis, and improves the treatment effect.

[0035] The functional coating of this invention can be used for the functional modification of bare metal vascular stent surfaces. Vascular stents coated with this functional coating can selectively promote endothelial cell adhesion and proliferation at the implantation site, achieving rapid endothelialization, while simultaneously releasing anti-proliferative drugs in a controllable manner to inhibit excessive proliferation of vascular smooth muscle cells. This selectivity creates the prerequisites for both "rapid endothelialization" and "inhibition of intimal hyperplasia," reducing the risk of restenosis and late thrombosis at the source.

[0036] The functional coating of this invention has good substrate adaptability and application versatility. It is not only suitable for surface modification of various metals and biodegradable stents, but can also be widely used in other interventional medical devices such as artificial blood vessels and drug-eluting balloons, showing broad clinical application prospects and translational potential. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the effect of the functional coating bracket in Example 1.

[0038] Figure 2 This is a top view of the functional coating bracket of Embodiment 1.

[0039] Figure 3 The results are from in vitro drug release tests of Examples 1-7 and Comparative Examples 1-3.

[0040] Figure 4 The results are from cell selectivity assays of Examples 1-7 and Comparative Examples 1-3. Detailed Implementation

[0041] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0042] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0043] Unless otherwise specified, the temperature in the embodiments of the present invention is room temperature or ambient temperature; room temperature or ambient temperature refers to 25±1℃.

[0044] The raw materials used in the embodiments and comparative examples of this invention are described below, but are not limited to the following materials: The monomers N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride (DAP) and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride (Ph) used in the embodiments and comparative examples of this invention were obtained in-house. The preparation method is based on existing published literature: Zhou, M., Xiao, X., Cong, Z., Wu, Y., Zhang, W., Ma, P., …Zhang, D. (2020). Water‐Insensitive Synthesis of Poly‐β‐Peptides with Defined Architecture. Angewandte Chemie International Edition, 59(18), 7240–7244. https: / / doi.org / 10.1002 / anie.202001697.

[0045] The stainless steel brackets used in the embodiments and comparative examples of this invention are 3mm×18mm laser-cut 304 stainless steel brackets customized by Shenzhen Shoute Steel Co., Ltd. Example

[0046] (1) Synthesis of β-peptide polymers: Weigh appropriate amounts of monomers N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride (DAP) and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride (Ph), and dissolve them separately in anhydrous N,N-dimethylformamide (DMF) to prepare monomer solutions with a concentration of 0.5 mol / L. Similarly, weigh appropriate amounts of 4-(tert-butyl)benzylamine (tBuBz-NH2) and dissolve them in DMF to prepare initiator solutions with a concentration of 0.1 mol / L. Slowly add 0.09 mL of DAP solution and 0.21 mL of Ph solution (DAP to Ph molar ratio of 3:7) dropwise to 0.1 mL of initiator solution, add a stir bar, and stir at 200 rpm at room temperature. Monitor the reaction by thin-layer chromatography (TLC). After the reaction was complete, 2 mL of tetrahydrofuran (THF) was added to rinse the solution and the mixture was transferred to a 50 mL centrifuge tube. 45 mL of petroleum ether was added, resulting in a white flocculent precipitate. The reaction solution was centrifuged at 4500 rpm for 2 minutes, and the supernatant was discarded. 2 mL of THF was added again to dissolve the precipitate, followed by centrifugation and discarding the supernatant. This process was repeated three times to obtain a white solid (protected polymer). The white solid was dried in a vacuum oven for 2 days, then dissolved in 3 mL of trifluoroacetic acid. An equal volume of 33% hydrogen bromide-acetic acid solution (HBr·HOAc) was added, and the mixture was stirred at room temperature for 12 h. The solvent was removed by rotary evaporation, and 3 mL of methanol was added to dissolve the solid. 45 mL of methyl tert-butyl ether pre-cooled to -20°C was added to precipitate the solid. The mixture was centrifuged, and the supernatant was discarded. This process was repeated three times, and the product was dried under vacuum to obtain a white solid. The white solid product was dissolved in double-distilled water, dialyzed for 2 h to remove small molecule impurities, filtered through a 0.45 μm filter membrane, and lyophilized to prepare the β-peptide polymer DAP7-Ph. 11 .

[0047] The number-average molecular weight (Mn) of the synthesized β-peptide polymer was determined to be 3670, and the molecular weight distribution (PDI) was 1.23, as determined by gel permeation chromatography. 1 H NMR spectroscopy characterization determined that the molar ratio of DAP units to Ph units in the polymer was 7:11, which is lower than the feed ratio (3:7). Analysis suggests that this may be due to the steric hindrance effect of the benzene ring side groups, which leads to a relative decrease in the reactivity of the monomer during the polymerization process.

[0048] (2) Preparation of β-peptide-polyester block copolymer: Weigh 100 mg of the β-peptide polymer (DAP7-Ph) obtained in step (1). 11The β-peptide polymer solution was obtained by dissolving 50 mg of PLGA-NHS (intrinsic viscosity 0.75-0.85 dL / g, purchased from Xi'an Qiyue Biotechnology) in 0.2 mL of DMF to obtain a PLGA-NHS solution, which was then added dropwise to the β-peptide polymer solution and reacted in a shaker at 4℃ for 12 h. The reaction solution was transferred to a dialysis bag and dialyzed for 3 days to remove unreacted impurities. After filtration through a 0.45 μm filter membrane, the solution was lyophilized to obtain the β-peptide-polyester block copolymer DAP7-Ph. 11 -PLGA.

[0049] The β-peptide-polyester block copolymer DAP7-Ph was determined by the ortho-phthalaldehyde (OPA) method. 11 -The amino grafting rate of PLGA is 0.4%.

[0050] (3) Preparation of functional coating scaffold: Weigh an appropriate amount of the β-peptide-polyester block copolymer (DAP7-Ph) obtained in step (2). 11 -PLGA) and rapamycin were dissolved in a dichloromethane-methanol solution (volume ratio 8:2) to prepare a coating solution. The mass concentration of rapamycin was 5%. DAP7-Ph 11 The PLGA concentration was 9%; the coating solution was then uniformly sprayed onto the surface of the stainless steel support, allowed to evaporate at room temperature for 60 seconds, and the spraying was repeated until the dosage reached 2 μg / mm². 2 A functional coated scaffold was prepared. Example

[0051] (1) Synthesis of β-peptide polymers: Weigh appropriate amounts of monomers N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride (DAP) and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride (Ph), and dissolve them separately in anhydrous N,N-dimethylformamide (DMF) to prepare monomer solutions with a concentration of 0.5 mol / L. Similarly, weigh appropriate amounts of 4-(tert-butyl)benzylamine (tBuBz-NH2) and dissolve them in DMF to prepare initiator solutions with a concentration of 0.1 mol / L. Slowly add 0.15 mL of DAP solution and 0.15 mL of Ph solution (DAP to Ph molar ratio of 1:1) dropwise to 0.1 mL of initiator solution, add a stir bar, and stir at 200 rpm at room temperature. Monitor the reaction by thin-layer chromatography (TLC). After the reaction was complete, 2 mL of tetrahydrofuran (THF) was added to rinse the solution and the mixture was transferred to a 50 mL centrifuge tube. 45 mL of petroleum ether was added, resulting in a white flocculent precipitate. The reaction solution was centrifuged at 4500 rpm for 2 minutes, and the supernatant was discarded. 2 mL of THF was added again to dissolve the precipitate, and the mixture was precipitated with petroleum ether. This process was repeated three times to obtain a white solid (protected polymer). The white solid was dried in a vacuum oven for 2 days, then dissolved in 3 mL of trifluoroacetic acid. An equal volume of 33% hydrogen bromide-acetic acid solution (HBr·HOAc) was added, and the mixture was stirred at room temperature for 12 h. The solvent was removed by rotary evaporation, and 3 mL of methanol was added to dissolve the solid. 45 mL of methyl tert-butyl ether pre-cooled to -20°C was added to precipitate the solid. The mixture was centrifuged, and the supernatant was discarded. This process was repeated three times, and the product was dried under vacuum to obtain a white solid. The white solid product was dissolved in double-distilled water, dialyzed for 2 h to remove small molecule impurities, filtered through a 0.45 μm filter membrane, and lyophilized to prepare the β-peptide polymer DAP. 10 -Ph8.

[0052] The number-average molecular weight (Mn) of the synthesized β-peptide polymer was 3534, and the molecular weight distribution (PDI) was 1.19, as determined by gel permeation chromatography. 1 Characterization by 1H NMR spectroscopy determined that the molar ratio of DAP units to Ph units in the polymer was 10:8.

[0053] The remaining steps are the same as in Example 1, and a functional coated scaffold is prepared. Example

[0054] (1) Synthesis of β-peptide polymers: Weigh appropriate amounts of monomers N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride (DAP) and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride (Ph), and dissolve them separately in anhydrous N,N-dimethylformamide (DMF) to prepare monomer solutions with a concentration of 0.5 mol / L. Similarly, weigh appropriate amounts of 4-(tert-butyl)benzylamine (tBuBz-NH2) and dissolve them in DMF to prepare initiator solutions with a concentration of 0.1 mol / L. Slowly add 0.21 mL of DAP solution and 0.09 mL of Ph solution (DAP to Ph molar ratio of 7:3) dropwise to 0.1 mL of initiator solution, add a stir bar, and stir at 200 rpm at room temperature. Monitor the reaction by thin-layer chromatography (TLC). After the reaction was complete, 2 mL of tetrahydrofuran (THF) was added to rinse the solution and the mixture was transferred to a 50 mL centrifuge tube. 45 mL of petroleum ether was added, resulting in a white flocculent precipitate. The reaction solution was centrifuged at 4500 rpm for 2 minutes, and the supernatant was discarded. 2 mL of THF was added again to dissolve the precipitate, and the mixture was precipitated with petroleum ether. This process was repeated three times to obtain a white solid (protected polymer). The white solid was dried in a vacuum oven for 2 days, then dissolved in 3 mL of trifluoroacetic acid. An equal volume of 33% hydrogen bromide-acetic acid solution (HBr·HOAc) was added, and the mixture was stirred at room temperature for 12 h. The solvent was removed by rotary evaporation, and 3 mL of methanol was added to dissolve the solid. 45 mL of methyl tert-butyl ether pre-cooled to -20°C was added to precipitate the solid. The mixture was centrifuged, and the supernatant was discarded. This process was repeated three times, and the product was dried under vacuum to obtain a white solid. The white solid product was dissolved in double-distilled water, dialyzed for 2 h to remove small molecule impurities, filtered through a 0.45 μm filter membrane, and lyophilized to prepare the β-peptide polymer DAP. 14 -Ph4.

[0055] The number-average molecular weight (Mn) of the synthesized β-peptide polymer was determined to be 3376, and the molecular weight distribution (PDI) was 1.25, as determined by gel permeation chromatography. 1 Characterization by 1H NMR spectroscopy determined that the molar ratio of DAP units to Ph units in the polymer was 14:4.

[0056] The remaining steps are the same as in Example 1, and a functional coated scaffold is prepared. Example

[0057] The difference between this embodiment and Example 1 is that the biodegradable polymer used in step (2) of the preparation of the β-peptide-polyester block copolymer is PCL-NHS (intrinsic viscosity of 1.0-1.1 dL / g, purchased from Xi'an Qiyue Biotechnology).

[0058] The remaining steps are the same as in Example 1, and a functional coated scaffold is prepared. Example

[0059] The difference between this embodiment and Embodiment 1 is that: The biodegradable polymer used in step (2) of the preparation of the β-peptide-polyester block copolymer is PLA-NHS (intrinsic viscosity of 0.5-0.6 dL / g, purchased from Xi'an Qiyue Biotechnology).

[0060] The remaining steps are the same as in Example 1, and a functional coated scaffold is prepared. Example

[0061] The difference between this embodiment and embodiment 1 is that in step (3), DAP7-Ph 11 The mass concentration of PLGA was 12%, and the remaining steps were the same as in Example 1 to prepare a functional coated scaffold. Example

[0062] The difference between this embodiment and embodiment 1 is that in step (3), DAP7-Ph 11 The mass concentration of PLGA was 20%. The remaining steps were the same as in Example 1, and a functional coated scaffold was prepared.

[0063] Comparative Example 1: Weigh appropriate amounts of PLGA (Jinan Daigang Biotechnology Co., Ltd., intrinsic viscosity 0.75-0.85 dL / g) and rapamycin, dissolve them in dichloromethane-methanol solution (volume ratio 8:2) to prepare a coating solution. The mass concentration of rapamycin is 5%, and the mass concentration of PLGA is 9%. Then, uniformly spray the coating solution onto the surface of the stainless steel support, allow it to evaporate at room temperature for 60 seconds, and repeat the spraying until the drug concentration reaches 2 μg / mm². 2 A functional coated scaffold was prepared.

[0064] Comparative Example 2 This comparative example demonstrates the fabrication of a double-sided coated scaffold: (1) β-peptide polymer DAP7-Ph 11 The synthesis is the same as in Example 1; (2) Preparation of functional coated scaffolds: Inner surface drop coating: Weigh an appropriate amount of DAP7-Ph 11 The coating solution was prepared by dissolving the substance in a dichloromethane-methanol solution (volume ratio 8:2), DAP7-Ph 11 The mass concentration was 9%; then the coating solution was uniformly drop-coated onto the inner surface of the stainless steel support, allowed to evaporate at room temperature for 60 s, and the drop-coating was repeated until the mass of the β-peptide polymer reached 1 μg / mm. 2 .

[0065] External surface coating: Weigh appropriate amounts of PLGA (Jinan Daigang Biotechnology Co., Ltd., intrinsic viscosity 0.75-0.85 dL / g) and rapamycin, dissolve them in dichloromethane-methanol solution (volume ratio 8:2) to prepare a coating solution. The mass concentration of rapamycin is 5%, and the mass concentration of PLGA is 9%. Then, uniformly spray the coating solution onto the surface of the stainless steel support, allow it to evaporate at room temperature for 60 seconds, and repeat the spraying until the drug concentration reaches 2 μg / mm². 2 .

[0066] Comparative Example 3 Physically mixed coating: Weigh appropriate amounts of PLGA (Jinan Daigang Biotechnology Co., Ltd., intrinsic viscosity 0.75-0.85 dL / g) and DAP7-Ph 11 A coating solution was prepared by dissolving rapamycin in a dichloromethane-methanol solution (volume ratio 8:2). The mass concentration of rapamycin was 5%. (DAP7-Ph) 11 The mass concentration of both PLGA and the coating solution was 9%; then the coating solution was uniformly sprayed onto the surface of the stainless steel support, allowed to evaporate at room temperature for 60 seconds, and the spraying was repeated until the dosage reached 2 μg / mm². 2 A functional coated scaffold was prepared.

[0067] Performance testing: 1. In vitro drug release test: The functionally coated scaffolds of the examples and comparative examples were placed in test tubes, and 15 mL of phosphate buffer (0.1 mol / L, pH 7.4) containing 4% fetal bovine serum was added as the release medium. The test tubes were placed in a 37 °C water bath shaker and shaken at 100 rpm. The release medium was changed every week. The scaffolds were removed at 1, 3, 7, 14, 30, 60, 90, and 120 days, and the residual drug in the scaffolds was quantitatively analyzed by high-performance liquid chromatography (HPLC). The experimental results of the examples and comparative examples are as follows: Figure 3 As shown.

[0068] Experimental results showed that Examples 1-7 could controllably release the antiproliferative drug. The amino acid composition (DAP to Ph ratio) of the β-peptide polymer had little effect on the drug release rate. Examples 1, 2, and 3 showed rapid initial release on the first day, with a cumulative release rate exceeding 40%, followed by a sustained slow release, reaching a cumulative release rate exceeding 80% by day 90. The type and properties of the polyester block significantly affected the release kinetics. Compared to Example 1, with the same β-peptide composition, Example 4 (using PCL-NHS with higher intrinsic viscosity) had the flattest release curve; while Example 5 (using PLA-NHS with lower intrinsic viscosity) had the fastest release rate. This indicates that the release behavior can be controlled by selecting the polyester type. The concentration of the β-peptide-polyester block copolymer in the coating affected drug release. In Examples 6 and 7 (β-peptide-polyester block copolymer concentrations of 12% and 20%, respectively), compared to Example 1 (9%), the drug release rate decreased with increasing copolymer concentration.

[0069] The comparative examples highlight the advantages of the functional coatings of this invention. The release curves of Comparative Example 1 (pure PLGA coating) and Comparative Example 2 (double-sided coating) are similar to those of Examples 1-7; however, Comparative Example 3 (physically mixed coating) exhibited a rapid burst release of up to 54.6% on the first day, and the cumulative release rate exceeded 80% by day 30, indicating poor controllability of drug release. This contrasts sharply with the stable and controllable release system formed by the covalently linked block copolymers in the embodiments of this invention.

[0070] 2. Cell selectivity assay: Experiments were conducted using primary human umbilical vein endothelial cells (HUVECs) and primary human umbilical artery smooth muscle cells (HUASMCs). Functionally coated scaffolds were cut into circular pieces with the same diameter as the 24-well plate using a punch, and both sides were sterilized by UV irradiation for 2 hours each. Uncoated plates served as controls. HUVECs and HUASMCs were added at 5 × 10⁶ cells per well. 4 Cells were seeded at a density of [number] cells per well, either coated or uncoated. After 24 h of culture, the old culture medium was discarded, and 10% CCK-8 solution was added. The cells were incubated at 37°C in the dark for 2 h, and the OD value at 450 nm was read using a microplate reader. Cell adhesion was calculated using the formula: Relative cell adhesion rate (%) = (OD experimental group - OD blank group) / (OD control group - OD blank group) × 100%. The experimental results of the examples and comparative examples are as follows... Figure 4 As shown.

[0071] Experimental results show that the functional coatings prepared in Examples 1-7 can selectively promote endothelial cell adhesion while effectively inhibiting smooth muscle cell adhesion. The amino acid composition of the β-peptide polymer (the ratio of DAP to Ph) affects the adhesion effect of endothelial cells. Example 1 (DAP7-Ph) 11 The endothelial cell adhesion rate of PLGA was higher than that of DAP in Example 2. 10 -Ph8-PLGA), Example 3 (DAP) 14 -Ph4-PLGA).

[0072] The experimental results of Comparative Example 1 show that, compared with the control group, the functional coating prepared therein exhibits a significant inhibitory effect on the adhesion of both endothelial cells and smooth muscle cells.

[0073] In the cell selectivity assay of Comparative Example 2, only the inner surface (β-peptide coating) exhibited a selective endothelial / smooth muscle cell adhesion-promoting effect similar to that of the present invention; while the outer surface (PLGA-rapamycin coating) showed an inhibitory effect on the adhesion of both types of cells, similar to Comparative Example 1. Compared to the unified β-peptide-polyester block copolymer coating in the examples, which combines drug release and endothelial promotion functions, the double-sided coating of Comparative Example 2 has significant limitations in promoting endothelialization of the scaffold's outer surface.

[0074] The physical hybrid coating of Comparative Example 3 showed a significant inhibitory effect on the adhesion of vascular smooth muscle cells, but its effect on promoting the adhesion of vascular endothelial cells was lower than that of Example 1 of the present invention.

[0075] In summary, this invention successfully prepared a coating that simultaneously achieves the dual functions of "selectively promoting endothelial cell adhesion" and "loading and controlling the release of antiproliferative drugs" within a single coating by forming a block copolymer with β-peptide polymer and biodegradable polyester through covalent bonding. This overcomes the defects of functional separation of double-sided coatings or functional imbalance of physically mixed coatings in the comparative example.

[0076] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A functional coating, characterized in that, It includes endothelialization-promoting active substances and antiproliferative drugs; the endothelialization-promoting active substances include at least one of the following: polypeptides containing RGD sequence, polypeptides containing YIGSR sequence, polypeptides containing REDV sequence, β-peptide polymers, or β-peptide-polyester block copolymers; The β-peptide-polyester block copolymer is a block copolymer formed by the reaction of a β-peptide polymer with a degradable polyester having an NHS ester terminus to form amide bonds. The monomer for the β-peptide polymer is β-amino acid-N-thiocarboxylic anhydride; the structural formula of the β-amino acid-N-thiocarboxylic anhydride is as follows: R1 and R2 are each independently selected from any one of hydrogen, phenyl, n-butyl, benzyloxycarbonylamino, and benzyloxycarbonyl.

2. The functional coating according to claim 1, characterized in that, The endothelialization-promoting active substance is a β-peptide-polyester block copolymer; the antiproliferative drug is selected from at least one of rapamycin, paclitaxel, everolimus, zotamoxetine, and gemcitabine.

3. The functional coating according to claim 1, characterized in that, The β-amino acid-N-thiocarboxylic anhydride is selected from at least one of N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride.

4. The functional coating according to claim 1, characterized in that, The β-peptide polymer is a random copolymer obtained by the polymerization reaction of N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride and 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride; the molar ratio of structural units derived from N(α)-benzyloxycarbonyl-DL-2,3-diaminopropionic acid N-thiocarboxylic anhydride to structural units derived from 3-amino-2-(phenyl)propionic acid N-thiocarboxylic anhydride in the β-peptide polymer is 1:(0.2-5).

5. The functional coating according to claim 1, characterized in that, The β-peptide polymer has a number-average molecular weight of 3000-6000 and a molecular weight distribution of 1.0-2.

0.

6. The functional coating according to claim 1, characterized in that, The biodegradable polyester with NHS ester ends is selected from at least one of PLA-NHS, PLGA-NHS, PCL-NHS, PLCL-NHS, and PU-NHS.

7. The functional coating according to claim 1, characterized in that, The amino grafting rate of the β-peptide-polyester block copolymer is 0.3-0.

7.

8. The use of the functional coating according to any one of claims 1-7 in the preparation of vascular interventional medical devices or neurointerventional medical devices.

9. A vascular stent, characterized in that, It includes a bare metal support and a coating applied to the surface of the support; the coating is the functional coating as described in any one of claims 1-7.

10. The method for preparing a vascular stent according to claim 9, characterized in that, The process includes the following steps: dissolving antiproliferative drugs and endothelialization-promoting active substances in a solvent to prepare a coating solution; uniformly coating the coating solution onto the surface of a bare metal scaffold to form a functional coating.

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