A wet adhesion-enhanced vascular stent graft and method of making the same

Abstract

The present application belongs to the field of biomedical materials, and relates to the preparation of a vascular stent covering, in particular to a wet adhesion enhanced vascular stent covering and a preparation method thereof. The present application constructs a synergistic interface with silk fibroin or silk sericin and biomimetic adhesion functional molecules as the core, utilizes multiple non-covalent interactions such as hydrogen bonds, pi-pi stacking and coordination, and covalent interactions such as Schiff base / Michael addition, significantly reduces the risk of stent displacement after surgery, and at the same time endows the covering with excellent biocompatibility and anti-inflammatory properties. Combined with the film forming strategy of 3D direct writing combined with rotary drying, a continuous and uniform covering with adjustable thickness and soft matching with the stent is obtained, thereby effectively solving the technical problems of insufficient adhesion and easy displacement of the existing covering stent in a wet environment, and is expected to improve the long-term patency rate, and has a broad market application prospect.

Description

Technical Field

[0001] This invention relates to the preparation of vascular stent coatings, specifically to a wet adhesion-enhanced vascular stent coating and its preparation method. Background Technology

[0002] In current clinical treatment, covered stents are widely used in interventional treatment of aneurysms, aortic dissections and other vascular lesions. By forming a barrier layer outside the metal or polymer stent, the lesion segment is isolated and reconstructed. However, there is still a high proportion of stent migration problems after the operation. Once it occurs, it can induce serious complications such as distal tissue ischemia, aggravation of dissection, aneurysm enlargement or even rupture, which has become a key bottleneck restricting the efficacy and prognosis. Most of the existing covered materials are inert polymer materials such as polytetrafluoroethylene and polyester. Although these materials have excellent mechanical strength, they face the following limitations in the blood environment: (1) Insufficient adhesion at the wet interface. The hydration layer formed by blood and tissue fluid weakens the adhesion between the covered stent and the vascular intima, and stent migration is easy to occur under long-term shear flow; (2) Limited bioactivity and anti-inflammatory properties. The inert surface is not conducive to endothelial cell adhesion and proliferation, resulting in delayed endothelialization and inflammation, thereby increasing the risk of thrombosis and restenosis; (3) Poor wall conformability and flexibility, which easily forms blood turbulence and affects the long-term patency rate.

[0003] To enhance wet adhesion, biomimetic adhesive functional molecules have been explored in the field of tissue adhesives. Patent CN113368312A discloses a biodegradable self-adhesive hydrogel obtained through free radical polymerization of tea polyphenols and methacrylic anhydride-modified gelatin; patent CN114762737A reports the formation of a surface adhesion layer by soaking gelatin hydrogel in a tea polyphenol solution and then drying it; patent CN119564918A discloses a polyphenol-containing medical adhesive, which uses gelatin molecular chains as a backbone. First, gallic acid is used to deconstruct collagen and expose more active sites through hydrogen bonding, electrostatics, addition, and π–π stacking. Then, tea polyphenols are introduced and combined with gelatin chains through hydrogen bonding and hydrophobic interactions to form a polyphenol-protein network; patent CN120118335A discloses a highly adhesive enzymatic hydrogel with methacrylic anhydride-modified hyaluronic acid as a backbone grafted with dopamine and tyramine. However, existing reports mostly focus on soft tissue adhesion and planar substrate modification. In contrast, the tubular fabric substrate of the coated scaffold is hydrophobic, inert, and interwoven with fibers / yarns, lacking active groups on its surface that can be used for covalent coupling or strong interactions, making it difficult to construct a uniform, stable, and shear-resistant wet adhesion layer. Prior to the publication of this study, there were no publicly reported modifications to the surface of the coated tubular fabric of the scaffold to enhance wet adhesion.

[0004] Fibroin and sericin are natural animal proteins that have attracted attention due to their excellent biocompatibility and processability. However, effective strategies for constructing stable, wet, strong adhesive interfaces in a blood environment and achieving effective coupling with scaffold-coated tubular fabrics remain lacking. On the other hand, while conventional biomimetic adhesive functional molecules have the potential to construct biomimetic adhesion and anti-inflammatory properties, they struggle to achieve uniform and robust coupling with hydrophobic, inert, and fiber / yarn-interwoven tubular coating substrates, thus making it difficult to obtain erosion-resistant, long-term stable adhesive layers.

[0005] Therefore, it is necessary to develop a wet adhesion-enhanced modified vascular stent graft that can maintain high adhesion and long-term adhesion durability / fatigue resistance in high humidity and prolonged pulsatile blood flow shearing environments, in order to meet the clinical demand for strong wet adhesion and long-term positioning stability of the grafted stent. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to provide a vascular stent graft exhibiting strong wet adhesion and long-term positioning stability even under high humidity and prolonged blood shearing conditions, along with its preparation method. By constructing a synergistic interface centered on silk fibroin or sericin and biomimetic adhesion functional molecules, and utilizing multiple non-covalent interactions such as hydrogen bonding, π–π stacking, and coordination, as well as covalent interactions such as Schiff base / Michael addition, the risk of postoperative stent migration is significantly reduced, while simultaneously endowing the graft with excellent biocompatibility and anti-inflammatory properties. Combining a film-forming strategy of 3D direct writing with spin drying, a continuous, uniform, and thickness-adjustable graft that compliantly matches the stent is obtained, effectively solving the technical challenges of insufficient adhesion and easy migration of existing grafted stents in wet environments, and potentially improving long-term patency rates.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution;

[0008] A method for preparing a wet adhesion-enhanced vascular stent coating, comprising the following specific steps:

[0009] (1) Degumming of raw silkworm silk with boiling water, sodium carbonate, sodium bicarbonate or biological enzyme; after degumming, silkworm fibroin fiber is obtained, which is dissolved in lithium bromide solution or calcium chloride ternary solution to obtain fibroin protein solution. The fibroin protein solution is poured into a dialysis bag, dialyzed with deionized water and then evaporated and concentrated to obtain fibroin protein aqueous solution, which is then mixed with a hydrophilic and flexible crosslinking agent to obtain fibroin protein solution with a concentration of 10~200mg / mL.

[0010] Preferably, in step (1), during degumming, the solid-liquid ratio of raw silkworm silk to degumming solution is 1:50 g / mL, and the degumming solution is boiling water, sodium carbonate solution, sodium bicarbonate solution, or biological enzyme; the concentration of lithium bromide solution is 9.3 M, the calcium chloride ternary solution is a calcium chloride-ethanol-water ternary system with a molar ratio of 1:2:8; the dialysis bag is a semi-permeable membrane with a molecular weight cutoff of 3~50 kDa, and dialysis is performed with deionized water for 3 days at a temperature of 4°C; the mass ratio of silk fibroin to crosslinking agent is 1.0:(0.3~1.0), and the crosslinking agent is polyethylene glycol diglycidyl ether.

[0011] (2) Any one or more combinations of twisted yarn and polyester yarn are used to make tubular fabric by any one of the weaving methods of machine weaving, knitting and braiding; then the silk fibroin solution of step (1) is written on the surface of the tubular fabric by 3D direct writing method and rotated to dry. After drying, the direct writing is repeated several times in the same way to obtain vascular stent coating.

[0012] Preferably, in step (2), the direct writing conditions are: direct writing flow rate of 0.1~10mL / h, direct writing lateral movement speed of 0.1~10cm / min, rotation speed of 10~500rpm; drying temperature of 20~50℃; and the number of times the direct writing is repeated is 2~15 times.

[0013] (3) The raw silk of the silkworm is degummed by boiling water and then evaporated and concentrated to obtain an aqueous solution of sericin protein. This solution is then mixed with a hydrophilic and flexible crosslinking agent to obtain a sericin protein solution with a concentration of 1~40 mg / mL.

[0014] Preferably, in step (3), the bath ratio of raw silkworm silk to water is 1:20 g / mL, the mass ratio of sericin to crosslinking agent is 1.0:(0.3~1.0), and the crosslinking agent is polyethylene glycol diglycidyl ether.

[0015] (4) Prepare an aqueous solution of biomimetic adhesion functional molecules with a concentration of 5-60 mg / mL; the biomimetic adhesion functional molecules are any one of tea polyphenols, gallic acid, epigallocatechin gallate, tannic acid or dopamine; under heating conditions, add hydrogen peroxide to the aqueous solution of biomimetic adhesion functional molecules to carry out an oxidation reaction, and after the reaction, obtain a solution of biomimetic adhesion functional molecules containing partial oxidation.

[0016] Preferably, in step (4), the heating conditions are 20~50℃, the molar ratio of biomimetic adhesion functional molecules to hydrogen peroxide is 1:0~1:30, and the oxidation reaction time is 1~6 hours;

[0017] Subsequently, the above-mentioned solution containing partially oxidized biomimetic adhesion functional molecules is mixed and reacted with the silk fibroin solution of step (1) or the sericin solution of step (3) to promote Schiff base condensation and Michael addition, so as to obtain a biomimetic adhesion functional molecule-silk fibroin composite solution or a biomimetic adhesion functional molecule-sericin composite solution.

[0018] Preferably, in step (4), the volume ratio of the partially oxidized biomimetic adhesion functional molecule solution to the silk fibroin solution or sericin solution is 1.0:(0.1~1.0); the temperature of the mixing reaction is 20~50℃, and the reaction time is 1~12 hours.

[0019] (5) Using the 3D direct writing method, a solution of partially oxidized biomimetic adhesion functional molecules, or a solution of biomimetic adhesion functional molecules-silk fibroin composite, or a solution of biomimetic adhesion functional molecules-sericin composite is directly written onto the outer surface of the vascular stent coating obtained in step (2), and then rotated to dry. After drying, it is immersed in sterile deionized water to remove unreacted substances, including cross-linking agents, silk fibroin, sericin and biomimetic adhesion functional molecules, and finally wet adhesion modified vascular stent coating is obtained.

[0020] Preferably, in step (5), the direct writing flow rate is 0.1~10mL / h, the direct writing lateral movement speed is 0.1~10cm / min, the rotation speed is 10~500rpm, and the drying temperature is 20~50℃; the temperature of the sterile deionized water is 4~37℃, and the soaking time is 1~3 days.

[0021] The wet-adhesion modified vascular stent coating prepared by the above method has excellent biocompatibility and anti-inflammatory properties, can effectively improve adhesion in wet environments, and can maintain high adhesion and long-term positioning stability in high humidity and long-term pulsating blood flow shearing environments. Beneficial effects

[0022] The wet adhesion-enhanced modified vascular stent coating prepared in this invention maintains significant interfacial adhesion and long-term positioning stability under high humidity and prolonged blood shearing conditions, reducing the risk of postoperative stent displacement from the source. The mechanism lies in the covalent anchoring achieved through Schiff base condensation and Michael addition of the amino or thiol groups on the macrochain of silk fibroin or sericin with partially oxidized biomimetic adhesion functional molecules (tea polyphenols, gallic acid, epigallocatechin gallate, tannic acid, dopamine). This is achieved by 3D direct writing and composite with the silk fibroin layer on tubular fabric to form a uniformly covered and stably coupled wet-state strong adhesion interface, thus providing high initial adhesion and excellent long-term positioning stability under prolonged pulsatile blood flow shearing forces. Meanwhile, the above-mentioned film-forming process can obtain a continuous, uniform, and thickness-controllable coating that is flexible and matches the blood vessel, reducing undulations and turbulence on the inner surface of the lumen and improving long-term fit and patency; natural polyphenols endow the material with benefits such as scavenging reactive oxygen species and inhibiting inflammatory signals, which are expected to improve the medium- and long-term patency rate and optimize clinical prognosis. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary. Example 1:

[0025] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. It was then taken out and thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14 kDa and dialyzed with deionized water at 4℃ for 3 days. After dialysis, it was evaporated and concentrated to obtain a silk fibroin protein aqueous solution. Finally, it was mixed with a hydrophilic flexible crosslinking agent, wherein the mass ratio of silk fibroin protein to crosslinking agent was 1:0.5 and the crosslinking agent was polyethylene glycol diglycidyl ether, to obtain a silk fibroin protein solution with a concentration of 60 mg / mL.

[0026] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique; then, a silk fibroin solution was directly written onto the surface of the tubular fabric using a 3D direct writing method and then dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. After drying, the dried material was obtained, and the direct writing and drying process was repeated 6 times on the surface of the dried material in the same manner to obtain a vascular stent coating.

[0027] (3) Prepare an aqueous solution of epigallocatechin gallate with a concentration of 15 mg / mL. At 37°C, add hydrogen peroxide to the aqueous solution of epigallocatechin gallate for oxidation reaction, wherein the molar ratio of the reaction is 1:6 (epigallocatechin gallate:hydrogen peroxide). After 2 hours of oxidation reaction, a solution of partially oxidized epigallocatechin gallate is obtained.

[0028] (4) A solution containing partially oxidized epigallocatechin gallate was directly written onto the outer surface of the vascular stent coating using the 3D direct writing method and then dried by rotation. The direct writing flow rate was 2 mL / h, the direct writing lateral movement speed was 1 cm / min, the rotation speed was 150 rpm, and the drying temperature was 37℃. Then, it was soaked in sterile deionized water at 37℃ for 1 day to remove unreacted crosslinking agents, silk fibroin, and epigallocatechin gallate molecules, thus obtaining a wet-adhesion modified vascular stent coating.

[0029] Testing revealed that the vascular stent graft prepared in this invention significantly outperformed the control group in terms of interfacial adhesion and long-term positioning stability: its wet adhesion strength was 3.1 times higher than that of Control Example 1; and under simulated pulsatile blood flow conditions for 30 consecutive days in vitro, the graft displacement was reduced by 28% compared to Control Example 1. RAW264.7 macrophages treated with lipopolysaccharide were cultured on its surface for 3 days, and the expression level of the pro-inflammatory factor TNF-α was reduced by 39% compared to Control Example 1. Example 2:

[0030] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. After taking it out, it was thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14 kDa and dialyzed with deionized water at 4℃ for 3 days. After dialysis, it was evaporated and concentrated to obtain a silk fibroin protein aqueous solution. Finally, it was mixed with a hydrophilic flexible crosslinking agent with a mass ratio of silk fibroin protein to crosslinking agent of 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether to obtain a silk fibroin protein solution with a concentration of 60 mg / mL.

[0031] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique. Then, silk fibroin solution was directly written onto the surface of the tubular fabric using a 3D direct writing method and dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. After drying, the dried material was obtained, and the direct writing and drying process was repeated 6 times on the surface of the dried material in the same manner to obtain a vascular stent coating.

[0032] (3) Prepare an aqueous solution of epigallocatechin gallate with a concentration of 15 mg / mL. At 37°C, add hydrogen peroxide to the epigallocatechin gallate aqueous solution for oxidation, with a molar ratio of 1:6 (epigallocatechin gallate:hydrogen peroxide). After 2 hours of oxidation, a partially oxidized epigallocatechin gallate solution is obtained. Subsequently, the partially oxidized epigallocatechin gallate solution is mixed with a silk fibroin solution at a volume ratio of 1.0:1.0 and reacted at 37°C for 6 hours to obtain a biomimetic adhesion functional molecule-silk fibroin composite solution, denoted as the wet adhesion modified solution.

[0033] (4) The wet adhesion modified solution was directly written onto the outer surface of the vascular stent coating using the 3D direct writing method and then dried by rotation. The direct writing flow rate was 2 mL / h, the direct writing lateral movement speed was 1 cm / min, the rotation speed was 150 rpm, and the drying temperature was 37℃. After drying, the vascular stent coating was immersed in sterile deionized water at 37℃ for 1 day to remove unreacted cross-linking agents, silk fibroin, and epigallocatechin gallate molecules, thus obtaining the wet adhesion modified vascular stent coating.

[0034] Testing revealed that the vascular stent graft prepared in this invention significantly outperformed the control in terms of interfacial adhesion and long-term positioning stability: its wet adhesion strength was 18 times higher than that of control Example 1; and under simulated pulsatile blood flow conditions for 30 consecutive days in vitro, the graft displacement was reduced by 53% compared to control Example 1. RAW264.7 macrophages treated with lipopolysaccharide were cultured on its surface for 3 days, and the expression level of the pro-inflammatory factor TNF-α was reduced by 64% compared to control Example 1. Example 3:

[0035] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. After taking it out, it was thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14 kDa and dialyzed with deionized water at 4℃ for 3 days. After dialysis, it was evaporated and concentrated to obtain a silk fibroin protein aqueous solution. Finally, it was mixed with a hydrophilic flexible crosslinking agent with a mass ratio of silk fibroin protein to crosslinking agent of 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether to obtain a silk fibroin protein solution with a concentration of 60 mg / mL.

[0036] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique. Then, silk fibroin solution was directly written onto the surface of the tubular fabric using a 3D direct writing method and dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. After drying, the dried material was obtained, and the direct writing and drying process was repeated 6 times on the surface of the dried material in the same manner to obtain a vascular stent coating.

[0037] (3) Prepare an aqueous solution of epigallocatechin gallate with a concentration of 30 mg / mL. At 37°C, add hydrogen peroxide to the epigallocatechin gallate aqueous solution for oxidation, with a molar ratio of 1:6 (epigallocatechin gallate:hydrogen peroxide). After 2 hours of oxidation, a partially oxidized epigallocatechin gallate solution is obtained. Subsequently, the partially oxidized epigallocatechin gallate solution is mixed with a silk fibroin solution at a volume ratio of 1.0:1.0 and reacted at 37°C for 6 hours to obtain a biomimetic adhesion functional molecule-silk fibroin composite solution, denoted as the wet adhesion modified solution.

[0038] (4) The wet adhesion modified solution was directly written on the outer surface of the vascular stent coating using the 3D direct writing method and then rotated to dry. The direct writing flow rate was 2 mL / h, the direct writing lateral movement speed was 1 cm / min, the rotation speed was 150 rpm, and the drying temperature was 37℃. Then, it was soaked in sterile deionized water at 37℃ for 1 day to remove unreacted cross-linking agents, silk fibroin, and epigallocatechin gallate molecules, thus obtaining the wet adhesion modified vascular stent coating.

[0039] Testing revealed that the vascular stent graft prepared in this invention significantly outperformed the control in terms of interfacial adhesion and long-term positioning stability: its wet adhesion strength was 39 times higher than that of control Example 1; and under simulated pulsatile blood flow conditions in vitro for 30 consecutive days, the graft displacement was reduced by 83% compared to control Example 1. RAW264.7 macrophages treated with lipopolysaccharide were cultured on its surface for 3 days, and the expression level of the pro-inflammatory factor TNF-α was reduced by 84% compared to control Example 1.

[0040] Implementation: 4:

[0041] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. After taking it out, it was thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14 kDa and dialyzed with deionized water at 4℃ for 3 days. After dialysis, it was evaporated and concentrated to obtain a silk fibroin protein aqueous solution. Finally, it was mixed with a hydrophilic flexible crosslinking agent with a mass ratio of silk fibroin protein to crosslinking agent of 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether to obtain a silk fibroin protein solution with a concentration of 60 mg / mL.

[0042] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique. The surface of the fabric was then directly written with silk fibroin solution using a 3D direct writing method and dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. After drying, the dried material was obtained, and the direct writing and drying process was repeated 6 times on the surface of the dried material in the same manner to obtain a vascular stent coating.

[0043] (3) Prepare an aqueous solution of tea polyphenols with a concentration of 30 mg / mL. At 37°C, add hydrogen peroxide to the aqueous solution of tea polyphenols for oxidation, with a molar ratio of 1:6 (tea polyphenols: hydrogen peroxide). After 2 hours of oxidation, a partially oxidized tea polyphenol solution is obtained. Then, mix the partially oxidized tea polyphenol solution with a silk fibroin solution at a volume ratio of 1.0:1.0 and react at 37°C for 6 hours to obtain a biomimetic adhesion functional molecule-silk fibroin composite solution, denoted as the wet adhesion modified solution.

[0044] (4) The wet adhesion modified solution was directly written on the outer surface of the vascular stent coating using the 3D direct writing method and then rotated to dry. The direct writing flow rate was 2 mL / h, the direct writing lateral movement speed was 1 cm / min, the rotation speed was 150 rpm, and the drying temperature was 37℃. Then, it was soaked in sterile deionized water at 37℃ for 1 day to remove unreacted cross-linking agents, silk fibroin, and tea polyphenol molecules, thus obtaining the wet adhesion modified vascular stent coating.

[0045] Testing revealed that the vascular stent graft prepared in this invention significantly outperformed the control in terms of interfacial adhesion and long-term positioning stability: its wet adhesion strength was 32 times higher than that of control Example 1; and under simulated pulsatile blood flow conditions in vitro for 30 consecutive days, the graft displacement was reduced by 75% compared to control Example 1. RAW264.7 macrophages treated with lipopolysaccharide were cultured on its surface for 3 days, and the expression level of the pro-inflammatory factor TNF-α was reduced by 77% compared to control Example 1. Example 5:

[0046] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. After taking it out, it was thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14 kDa and dialyzed with deionized water at 4℃ for 3 days. After dialysis, it was evaporated and concentrated to obtain a silk fibroin protein aqueous solution. Finally, it was mixed with a hydrophilic flexible crosslinking agent with a mass ratio of silk fibroin protein to crosslinking agent of 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether to obtain a silk fibroin protein solution with a concentration of 60 mg / mL.

[0047] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique. The surface of the fabric was then directly written with silk fibroin solution using a 3D direct writing method and dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. After drying, the dried material was obtained, and the direct writing and drying process was repeated 6 times on the surface of the dried material in the same manner to obtain a vascular stent coating.

[0048] (3) The raw silk of the silkworm was dissolved and degummed in boiling water at 100℃ for 4 hours at a bath ratio of 1:20 g / mL. After evaporation and concentration, an aqueous solution of sericin was obtained. Finally, it was mixed with a hydrophilic and flexible crosslinking agent. The mass ratio of sericin to crosslinking agent was 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether, and a sericin solution with a concentration of 15 mg / mL was obtained.

[0049] (4) Prepare an aqueous solution of epigallocatechin gallate with a concentration of 30 mg / mL. At 37°C, add hydrogen peroxide to the epigallocatechin gallate aqueous solution for oxidation, wherein the molar ratio of epigallocatechin gallate to hydrogen peroxide is 1:6. After 2 hours of oxidation, a partially oxidized epigallocatechin gallate solution is obtained. Subsequently, the partially oxidized epigallocatechin gallate solution is mixed with a sericin solution at a volume ratio of 1.0:1.0, and reacted at 37°C for 6 hours to obtain a biomimetic adhesion functional molecule-sericein composite solution, denoted as the wet adhesion modified solution.

[0050] (5) The wet adhesion modified solution was directly written on the outer surface of the vascular stent coating using the 3D direct writing method and then dried by rotation. The direct writing flow rate was 2 mL / h, the direct writing lateral movement speed was 1 cm / min, the rotation speed was 150 rpm, and the drying temperature was 37℃. Then, it was soaked in sterile deionized water at 37℃ for 1 day to remove unreacted cross-linking agents, silk fibroin, sericin, and epigallocatechin gallate molecules, thus obtaining the wet adhesion modified vascular stent coating.

[0051] Testing revealed that the vascular stent graft prepared in this invention significantly outperformed the control in terms of interfacial adhesion and long-term positioning stability: its wet adhesion strength was 43 times higher than that of control Example 1; and under simulated pulsatile blood flow conditions for 30 consecutive days in vitro, the graft displacement was reduced by 98% compared to control Example 1. RAW264.7 macrophages treated with lipopolysaccharide were cultured on its surface for 3 days, and the expression level of the pro-inflammatory factor TNF-α was reduced by 83% compared to control Example 1.

[0052] Comparative Example 1:

[0053] (1) The raw silk of the silkworm was placed in a sodium carbonate aqueous solution with a concentration of 1 g / mL at a solid-liquid ratio of 1:50 g / mL and treated at 98~100℃ for 30 minutes. After taking it out, it was thoroughly washed with deionized water to complete one heating treatment. The washed material was heated again in the same way, and this was repeated 3 times to obtain degummed silk fibroin. Then, it was placed in a 9.3M lithium bromide solution with a solid-liquid ratio of 1:10 g / mL and treated at 65℃ until completely dissolved to obtain silk fibroin protein solution. It was poured into a dialysis bag with a molecular weight cutoff of 14kDa and dialyzed with deionized water at 4℃ for 3 days. After evaporation and concentration, an aqueous solution of silk fibroin protein was obtained. Finally, it was mixed with a hydrophilic flexible crosslinking agent with a mass ratio of silk fibroin protein to crosslinking agent of 1:0.5. The crosslinking agent was polyethylene glycol diglycidyl ether, and a silk fibroin protein solution with a concentration of 60mg / mL was obtained.

[0054] (2) 40D polyester yarn was woven into a tubular fabric on a stainless steel rod (3mm in diameter) using a weaving technique. The surface of the fabric was then directly written with silk fibroin solution using a 3D direct writing method and dried by rotation. The direct writing flow rate was 2mL / h, the direct writing lateral movement speed was 1cm / min, the rotation speed was 150rpm, and the drying temperature was 37℃. The direct writing and drying were repeated 6 times. The fabric was then soaked in sterile deionized water at 37℃ for 1 day to remove unreacted crosslinking agent and silk fibroin, thus obtaining a vascular stent coating.

[0055] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a wet adhesion-enhanced vascular stent coating, characterized in that, Includes the following steps: (1) Degumming of raw silkworm silk with boiling water, sodium carbonate, sodium bicarbonate or biological enzyme; after degumming, silkworm fibroin fiber is obtained, which is dissolved in lithium bromide solution or calcium chloride ternary solution to obtain fibroin protein solution. The fibroin protein solution is poured into a dialysis bag, dialyzed with deionized water and then evaporated and concentrated to obtain fibroin protein aqueous solution, which is then mixed with a hydrophilic and flexible crosslinking agent to obtain fibroin protein solution with a concentration of 10~200mg / mL. (2) Any one or more combinations of twisted yarn and polyester yarn are used to make tubular fabric by any one of the weaving methods of machine weaving, knitting and braiding; then the silk fibroin solution of step (1) is written on the surface of the tubular fabric by 3D direct writing method and rotated to dry. After drying, the direct writing is repeated several times in the same way to obtain vascular stent coating. (3) The raw silk of the silkworm is degummed by boiling water and then evaporated and concentrated to obtain an aqueous solution of sericin protein, which is then mixed with a hydrophilic and flexible crosslinking agent to obtain a sericin protein solution with a concentration of 1~40 mg / mL. (4) Prepare an aqueous solution of biomimetic adhesion functional molecules with a concentration of 5-60 mg / mL; the biomimetic adhesion functional molecules are any one of tea polyphenols, gallic acid, epigallocatechin gallate, tannic acid or dopamine; under heating conditions, add hydrogen peroxide to the aqueous solution of biomimetic adhesion functional molecules to carry out an oxidation reaction, and after the reaction, obtain a solution containing partially oxidized biomimetic adhesion functional molecules; The above-mentioned solution of partially oxidized biomimetic adhesion functional molecules is then mixed and reacted with the silk fibroin solution of step (1) or the sericin solution of step (3) to obtain a biomimetic adhesion functional molecule-silk fibroin composite solution or a biomimetic adhesion functional molecule-sericin composite solution. (5) Using the 3D direct writing method, a solution of partially oxidized biomimetic adhesion functional molecules, or a solution of biomimetic adhesion functional molecules-silk fibroin composite, or a solution of biomimetic adhesion functional molecules-sericin composite is directly written onto the outer surface of the vascular stent coating obtained in step (2), and then rotated to dry. After drying, it is immersed in sterile deionized water to remove unreacted substances, including cross-linking agents, silk fibroin, sericin and biomimetic adhesion functional molecules, and finally wet adhesion modified vascular stent coating is obtained.

2. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (1), during degumming, the solid-liquid ratio of raw silkworm silk to degumming solution is 1:50 g / mL. The degumming solution is boiling water, sodium carbonate solution, sodium bicarbonate solution, or biological enzyme. The concentration of lithium bromide solution is 9.3 M. The calcium chloride ternary solution is a calcium chloride-ethanol-water ternary system with a molar ratio of 1:2:

8. The dialysis bag is a semi-permeable membrane with a molecular weight cutoff of 3~50 kDa. Dialysis is performed with deionized water for 3 days at a temperature of 4℃. The mass ratio of silk fibroin to crosslinking agent is 1.0:(0.3~1.0). The crosslinking agent is polyethylene glycol diglycidyl ether.

3. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (2), the conditions for direct writing are: direct writing flow rate of 0.1~10mL / h, direct writing lateral movement speed of 0.1~10cm / min, rotation speed of 10~500rpm; drying temperature of 20~50℃; and the number of times the direct writing is repeated is 2~15 times.

4. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (3), the bath ratio of raw silkworm silk to water is 1:20 g / mL, the mass ratio of sericin to crosslinking agent is 1.0:(0.3~1.0), and the crosslinking agent is polyethylene glycol diglycidyl ether.

5. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (4), the heating conditions are 20~50℃, the molar ratio of biomimetic adhesion functional molecules to hydrogen peroxide is 1:0~1:30, and the oxidation reaction time is 1~6 hours.

6. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (4), the volume ratio of the partially oxidized biomimetic adhesion functional molecule solution to the silk fibroin solution or sericin solution is 1.0:(0.1~1.0); the mixing reaction temperature is 20~50℃ and the time is 1-12h.

7. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, In step (5), the direct writing flow rate is 0.1~10mL / h, the direct writing lateral movement speed is 0.1~10cm / min, the rotation speed is 10~500rpm, and the drying temperature is 20~50℃.

8. The method for preparing a wet adhesion-enhanced vascular stent coating according to claim 1, characterized in that, The temperature of the sterile deionized water in step (5) is 4~37℃, and the soaking time is 1~3 days.

9. A wet adhesion-enhanced vascular stent coating prepared by any one of the methods described in claims 1-8.

10. The wet adhesion-enhanced vascular stent coating according to claim 9, characterized in that, The wet adhesion modified vascular stent coating has excellent biocompatibility and anti-inflammatory properties, which can improve adhesion in wet environments and maintain high adhesion and positioning stability in high humidity and long-term pulsatile blood flow shearing environments.