Small-caliber artificial blood vessel with three-layer structure and preparation method of small-caliber artificial blood vessel

Abstract

The invention discloses a small-caliber artificial blood vessel with a three-layer structure and a preparation method of the small-caliber artificial blood vessel. The artificial blood vessel is provided with three layers of tube walls, the inner layer is an ordered fiber layer, the middle layer is a disordered fiber layer, and the outer layer is an ordered fiber layer; the preparation method of the inner layer and the outer layer is melting near-field direct writing, and the preparation method of the middle layer is one of melting near-field direct writing or electrostatic spinning. The middle disordered fiber layer has fine fibers and a small aperture, the fiber diameter and the aperture of the fiber layer are adjustable, and the middle disordered fiber layer has good elasticity and compliance; the inner ordered fiber layer and the outer ordered fiber layer can realize ordered stacking of fibers at a specific angle, simulate the arrangement of human vascular collagen fibers, and quickly induce endothelialization and smooth muscle layer reconstruction, thereby effectively promoting vascular regeneration; the raw material is a synthetic or natural degradable high-molecular polymer, the biocompatibility is good, the preparation process is simple, and no organic solvent is added or only a small amount of organic solvent is used.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial blood vessel graft preparation, and particularly relates to a three-layer structured small-caliber artificial blood vessel and a preparation method thereof. Background Art

[0002] Cardiovascular disease is the leading cause of death in the world. The main cause of cardiovascular disease is arterial occlusion, which leads to reduced blood flow to the target organ. Vascular surgery, such as coronary artery bypass grafting and arteriovenous shunt surgery, requires biologically active vascular grafts. Autologous grafts, such as the saphenous vein and internal mammary artery, are the gold standard grafts for treating vascular occlusion. Usually two surgeries are required. The first surgery harvests the patient's own artery or vein, and the second surgery uses it as a graft to replace the original occluded artery to restore blood flow. The disadvantage of this type of graft is that it is easy to cause damage to the patient's donor site, and patients without available autologous grafts cannot be cured in this way. Vascular replacement and reconstruction surgery is widely performed worldwide to save many patients with cardiovascular and cerebrovascular diseases and victims of accidental injuries. Synthetic vascular grafts not only avoid the surgery of autologous blood vessel harvesting, but also provide patients with additional surgical opportunities. Although vascular grafts are widely used in the field of vascular surgery, patients and doctors often encounter challenges such as thrombosis, insufficient mechanical properties and compliance mismatch. These problems particularly significantly affect the success rate of small-diameter vascular graft replacement surgery and become the main source of surgical failure. For example, traditional synthetic grafts based on polyethylene terephthalate (PET) and expanded polytetrafluoroethylene (ePTFE) have been very successful in replacing large arteries (>6 mm) in clinical practice. However, the clinical application of such non-degradable synthetic artificial vascular grafts in small-caliber (<6 mm) vascular transplants such as coronary arteries is not ideal, mainly due to low long-term patency, easy formation of thrombosis and embolism, and severe intimal hyperplasia. Currently, the poor adaptability of vascular grafts has significantly aggravated the pain and economic burden of patients.

[0003] The natural blood vessels of healthy people, with their unique three-layer structure - the intima, the middle membrane and the adventitia, have excellent mechanical properties, hemodynamic efficiency and anti-thrombotic ability. Specifically, the proportion of collagen fibers in the adventitia is higher, so it has higher strength, which can inhibit excessive expansion and rupture under physiological pressure. The middle layer is mainly composed of smooth muscle cells, collagen and elastin, which can adapt to the contraction and relaxation of blood vessels under physiological pressure. The intima is mainly composed of endothelial cells and plays an important role in preventing thrombosis. Unfortunately, most of the existing vascular grafts on the market are single-layer structures, which are difficult to fully meet the comprehensive performance standards of natural blood vessels. In view of this, the development of a new type of vascular graft with high compliance and the ability to simulate the superior adaptability of natural blood vessels has become an urgent expectation of patients and doctors. In addition, if the growth microenvironment of endothelial cells is not ideal, the regenerated endothelial cells will gradually fall off, leading to thrombosis. The middle membrane can not only maintain a healthy endothelium, but also inhibit vascular stenosis. For example, studies have shown that contact-dependent communication between smooth muscle cells and endothelial cells can promote the proliferation of endothelial cells; conversely, damaged smooth muscle cells induce inflammation or their excessive proliferation causes restenosis. It can be seen that smooth muscle reconstruction plays a key role in the process of vascular regeneration. Accelerating the reconstruction of autologous smooth muscle is conducive to the rapid restoration of compliance, adapting to vascular pulsation, inducing spontaneous endothelialization, and ultimately ensuring its long-term patency.

[0004] The arrangement of collagen fibers in the natural extracellular matrix of human tissue plays an important role in maintaining tissue mechanics and function. In the three-layer structure of human blood vessels, the different orientations of collagen fibers in each layer can regulate the mechanical behavior of blood vessels and cell arrangement, and cell arrangement plays a vital role in the maturation and regeneration of functional tissues. The collagen fibers in the smooth muscle layer are arranged circumferentially at an angle of 65°, and the smooth muscle cells are also arranged circumferentially. It is worth noting that the directional growth of vascular smooth muscle cells along the circumferential direction of the vascular graft is crucial for the regeneration of small-diameter blood vessels, and its special arrangement plays a key role in the maturation and regeneration of natural blood vessels. Therefore, vascular grafts that can guide the circumferential arrangement of smooth muscle cells can effectively promote vascular regeneration. Electrospinning is currently the mainstream technology for manufacturing artificial vascular grafts. However, due to the deposition of micro-nano fibers, the pore size is small, and the fibers are stacked in disorder, the cell infiltration and tissue regeneration in the vascular graft are limited. With the extension of implantation time, the regenerated tissue inside the graft gradually degenerates, and the vascular wall calcifies, which can eventually lead to graft failure. Currently, there is no vascular graft specifically designed to effectively promote the regeneration of vascular endothelial cells and vascular smooth muscle cells.

[0005] When using traditional synthetic vascular grafts, doctors and patients often face multiple challenges, including thrombosis, insufficient mechanical properties, mismatched compliance, non-degradable materials, and significant intimal hyperplasia. Existing artificial blood vessels are mainly produced by electrospinning technology, and the deposition of micro-nano fibers easily forms small pores and disordered fibers, which limits the infiltration of cells inside the blood vessels and the ability of tissue regeneration. Summary of the invention

[0006] The purpose of the present invention is to provide a three-layer structured small-caliber artificial blood vessel and a preparation method thereof, so as to solve the problem that the current technology cannot accurately construct a microstructure that is conducive to the regeneration of vascular endothelial cells and vascular smooth muscle cells, thereby accelerating the natural regeneration process of blood vessels.

[0007] The invention discloses a small-caliber artificial blood vessel with a three-layer structure. The wall of the artificial blood vessel is composed of three layers, the inner layer is an ordered fiber layer, the middle layer is a disordered fiber layer, and the outer layer is an ordered fiber layer.

[0008] Both the inner and outer layers are ordered fiber layers, while the middle layer is a disordered fiber layer, which aims to simulate the complex structure of natural blood vessels and improve the biocompatibility and functionality of artificial blood vessels.

[0009] The three-layer structure design of the present invention, especially the combination of the ordered fiber layer of the inner and outer layers and the disordered fiber layer of the middle layer, can simulate the complex structure of blood vessels to a certain extent. In human tissue, the arrangement of collagen fibers in the natural extracellular matrix is ​​crucial to maintaining the mechanical properties and functions of tissues. Specifically, the delicate structure of blood vessels is composed of three layers, and the unique arrangement direction of collagen fibers in each layer accurately regulates the mechanical behavior of blood vessels and the cell distribution pattern. The orderly arrangement of cells is the core element in the process of functional tissue maturation and regeneration.

[0010] Preferably, the diameter of the inner fiber layer of the artificial blood vessel is 3 nm to 30 μm, the diameter of the middle fiber layer is 3 nm to 30 μm, and the diameter of the outer fiber layer is 3 nm to 30 μm; the distance between the inner and outer fiber layers is 5 μm to 300 μm.

[0011] Preferably, the number of fiber layers of the inner and outer ordered fiber layers of the artificial blood vessel is 2 to 50.

[0012] The present invention strictly controls the diameter and spacing of the inner and outer fibers, as well as the number of layers of the inner and outer ordered fiber layers, to ensure the accuracy and consistency of the artificial blood vessel structure; smaller fiber diameter, smaller pore size and ordered structure are conducive to cell adhesion and proliferation. By precisely controlling these parameters, it can be ensured that the artificial blood vessel has a similar structure and performance to the natural blood vessel at the microscopic level, thereby better simulating its physiological function. Consistency is not only conducive to product quality control, but also helps to improve its reliability and safety in clinical applications. Precise control of the diameter, spacing and number of layers of the fibers also helps to optimize the mechanical properties of the artificial blood vessels. By adjusting these parameters, accurate regulation of key performance indicators such as vascular tensile strength and elastic modulus can be achieved. When the diameter, spacing and number of layers of the fibers are optimized, the surface morphology and chemical properties of the blood vessels will also change accordingly, thereby affecting their interaction with surrounding tissues. By reducing unnecessary roughness and nonspecific adsorption sites, the risk of inflammatory and rejection reactions can be reduced, and the fusion and repair of blood vessels with surrounding tissues can be promoted.

[0013] Preferably, the fibers of the inner ordered fiber layer of the artificial blood vessel have a specific crossing angle of -20° to 80°; the fibers of the outer ordered fiber layer of the artificial blood vessel have a specific crossing or circumferential orientation distribution angle of -20° to 80°.

[0014] The inner and outer ordered fiber layers have specific cross or circumferential orientation distribution angles, which are designed to simulate the mechanical properties, blood flow characteristics and biological properties of natural blood vessels; in human tissue, the arrangement of collagen fibers in the natural extracellular matrix plays a key role in maintaining the mechanical properties and functions of tissues. In the complex structure of blood vessels, which are composed of three layers, the specific arrangement direction of collagen fibers in each layer can finely regulate the mechanical response and cell layout of blood vessels, and the orderly arrangement of cells is the core element of the development, maturation and regeneration of functional tissues.

[0015] Preferably, the crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 60° to 70°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is 60° to 70°.

[0016] Preferably, the crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 65°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is 65°.

[0017] Preferably, the artificial blood vessel is biodegradable, and the material is selected from synthetic polymers (such as polylactic acid, polycaprolactone, lactide-caprolactone copolymer, polydioxanone, lactide-glycolide copolymer and polyurethane, etc.), natural polymers (such as chitosan, hyaluronic acid, alginate, cellulose, starch, chondroitin sulfate, gelatin, silk fibroin, collagen, fibrin, serum albumin and elastin, etc.) or a combination thereof.

[0018] The present invention uses biodegradable materials including synthetic polymers (such as polylactic acid, polycaprolactone, lactide-caprolactone copolymer, polydioxanone, lactide-glycolide copolymer and polyurethane, etc.), natural polymers (such as chitosan, hyaluronic acid, alginate, cellulose, starch, chondroitin sulfate, gelatin, silk fibroin, collagen, fibrin, serum albumin and elastin, etc.) or combinations thereof, so that the artificial blood vessels can be gradually absorbed by the body after completing their replacement function, thereby reducing long-term foreign body reactions.

[0019] The biodegradable properties allow artificial blood vessels made of these materials to naturally blend into the body environment after completing their function as vascular substitutes, avoiding the long-term foreign body reaction that may be caused by traditional non-degradable materials. As the material gradually degrades, the interface between the artificial blood vessel and the surrounding tissue gradually blurs, reducing foreign body stimulation and thus reducing the risk of long-term foreign body reaction. The selection of biodegradable materials not only improves the safety of artificial blood vessels, but also improves their effectiveness by promoting mechanisms such as vascular regeneration.

[0020] The artificial blood vessel can be surface-modified, and the modified materials include polymers (such as polyacrylonitrile, polydimethylsiloxane, polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone and polystyrene, etc.), inorganic nanomaterials (such as silicon dioxide, carbon nanotubes, titanium dioxide, graphene and silver nanoparticles, etc.), growth factors (such as epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, keratinocyte growth factor and insulin-like growth factor, etc.) and other substances (such as natural polyphenols, polydopamine, biological enzymes, surfactants, antibacterial agents and silane coupling agents, etc.).

[0021] The artificial blood vessels can be loaded with drugs or bioactive substances, including antibacterial agents (such as antibiotics and antimicrobial peptides), anti-inflammatory drugs (such as glucocorticoids and non-steroidal anti-inflammatory drugs), analgesics (such as ibuprofen and acetaminophen), antiviral drugs (such as acyclovir and oseltamivir), anti-tumor drugs (such as paclitaxel and doxorubicin), natural flavonoids or polyphenols (such as quercetin and tea polyphenols), growth factors (such as epidermal growth factor and vascular endothelial growth factor), antioxidants (such as vitamin C and vitamin E), polypeptides or proteins (such as insulin and growth hormone), and gene drugs (such as DNA and siRNA).

[0022] The invention provides a method for preparing a three-layer structured small-caliber artificial blood vessel: the inner and outer layers are prepared by melt near-field direct writing, and the middle layer is prepared by melt near-field direct writing or electrostatic spinning.

[0023] The inner and outer ordered fiber layers are prepared by melt near-field direct writing technology to ensure the precise arrangement of the fibers. The micro-nano fibers prepared by the near-field direct writing process are precisely controllable. This technology has shown great potential in the field of micro-nano manufacturing with its high precision, high resolution and strong controllability; the precisely arranged fiber structure is crucial for simulating the mechanical properties and biological functions of natural blood vessels. By optimizing the arrangement direction and density of the fibers, key parameters such as the tensile strength and elastic modulus of the blood vessels can be regulated to make them closer to the performance of natural blood vessels. The orderly arranged fiber structure can also provide a suitable attachment and growth environment for cells, promoting biological repair processes such as endothelialization.

[0024] The middle disordered fiber layer of the present invention can be prepared by melt near-field direct writing or electrospinning technology, providing flexible process options to meet different performance requirements; through the two preparation technologies of melt near-field direct writing and electrospinning, the present invention enables manufacturers to flexibly select the most suitable preparation process according to different performance requirements, thereby optimizing the overall performance of the product.

[0025] Preferably, the preparation method is one-piece molding or separate preparation of the inner, middle and outer layer structures and then assembling and heat-sealing them.

[0026] The present invention provides two manufacturing processes: one-piece molding and separate preparation followed by assembly and heat sealing; the one-piece molding ensures close bonding between the layers by continuously printing the three-layer structure in the same process; while separate preparation followed by assembly and heat sealing provides more processing flexibility and material selection space.

[0027] One-piece molding enhances the overall structural strength of the product, improves its durability and service life, shortens the production cycle, and improves production efficiency. Assembly heat sealing can adjust the size, shape and material of each part according to actual needs. You can freely choose the material that best suits the needs of each layer.

[0028] Preferably, the one-piece molding includes the following steps: using near-field direct writing 3D printing technology to print an inner ordered fiber layer on a metal receiving rod of a specific diameter, then using near-field direct writing 3D printing technology or electrospinning technology to prepare a middle disordered fiber layer on the inner layer, and finally using near-field direct writing 3D printing technology to print an outer ordered fiber layer on the middle layer.

[0029] The present invention utilizes a combination of near-field direct writing 3D printing technology and electrospinning technology to achieve the precise construction of complex structures of small-caliber artificial blood vessels, demonstrating its advancement and innovation in the field of biomedical engineering. Near-field direct writing technology is known for its high precision and high resolution. It can accurately control the deposition position and shape of materials and is very suitable for manufacturing three-dimensional structures with fine features. Electrospun fibers have a high specific surface area, good flexibility and biocompatibility, and are very suitable for simulating the microstructure and function of natural blood vessel walls. This structure not only improves the mechanical properties of artificial blood vessels, but also enhances their compatibility with biological tissues and promotes cell adhesion and growth.

[0030] Preferably, the method of separately preparing the inner, middle and outer layer structures and then assembling and heat-sealing them comprises the following steps: respectively using near-field direct writing 3D printing technology to print the inner and outer ordered fiber layers, using near-field direct writing 3D printing technology or electrospinning technology to prepare the middle layer disordered fiber layer, and then socketing the three-layer structure and performing thermal bonding treatment.

[0031] The present invention provides a small-caliber artificial blood vessel with a three-layer structure. The inner and outer layers are constructed with ordered fiber layers. The fibers are stacked in an orderly manner at a specific angle (such as -20° to 80°, preferably 60° to 70°, and optimally 65°) to form a structure with a larger pore size and a higher porosity to promote cell infiltration and growth. The middle layer is designed as a disordered fiber layer. The fibers are randomly deposited to form a smaller pore size and a lower porosity, giving the blood vessel good elasticity and compliance.

[0032] The fiber crossing or circumferential orientation distribution angles of the inner and outer ordered fiber layers can be set independently. The same configuration or differentiated design can be selected to meet different biomechanical requirements.

[0033] The vascular material of the present invention is selected from synthetic polymers (such as polylactic acid, polycaprolactone, lactide-caprolactone copolymer, polydioxanone, lactide-glycolide copolymer and polyurethane, etc.), natural polymers (such as chitosan, hyaluronic acid, alginate, cellulose, starch, chondroitin sulfate, gelatin, silk fibroin, collagen, fibrin, serum albumin and elastin, etc.) or a combination thereof, which ensures the biocompatibility and degradation controllability of the product.

[0034] In terms of preparation methods, the inner and outer ordered fiber layers are precisely formed by melt near-field direct writing technology, while the middle disordered fiber layer can be prepared by melt near-field direct writing or electrospinning technology. The construction process can be carried out layer by layer, or it can be prepared separately and then assembled, that is, the inner, middle and outer three layers of fibers are combined under precise control and reinforced by heat sealing technology.

[0035] The inner diameter, layer thickness, fiber diameter and fiber spacing of the three-layer small-caliber blood vessels can be customized and manufactured according to clinical needs, thereby achieving precise control of the degradation time and meeting a variety of clinical medical application scenarios.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The three-layer structure of the small-caliber artificial blood vessel provided by the present invention has a middle layer of disordered fiber layer with finer fibers and smaller pores, and the fiber diameter and fiber layer pore size are adjustable, and has good elasticity and compliance.

[0038] 2. The three-layer structure of the small-caliber artificial blood vessel provided by the present invention can realize the orderly stacking of fibers at specific angles in the inner and outer ordered fiber layers, simulate the arrangement of collagen fibers in human blood vessels, and quickly induce endothelialization and reconstruction of the smooth muscle layer, thereby effectively promoting vascular regeneration.

[0039] 3. The raw materials of the product are synthetic or natural degradable polymers with good biocompatibility, simple preparation process, no organic solvents added or only a small amount of organic solvents used. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the three-layer small-caliber artificial blood vessel of the present invention;

[0041] Figure 2 The diagram is a cross-sectional view of the blood vessel wall after the three-layer structure of the small-caliber artificial blood vessel of the present invention is implanted into the human body.

[0042] In the figure: 1, outer layer, 2, middle layer, 3, inner layer, 4, endothelial cells, 5, smooth muscle cells. DETAILED DESCRIPTION

[0043] Example 1

[0044] like Figure 1 As shown, the present invention discloses a three-layer structure small-caliber artificial blood vessel, the tube wall has three layers, the inner layer 3 is an ordered fiber layer, the middle layer 2 is a disordered fiber layer, and the outer layer 1 is an ordered fiber layer.

[0045] The diameter of the inner fiber of the artificial blood vessel is 500nm, the diameter of the middle fiber is 30nm, and the diameter of the outer fiber is 500nm; the distance between the inner and outer fibers is 50μm.

[0046] The number of fiber layers of the inner and outer ordered fiber layers of the artificial blood vessel is 5.

[0047] The crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 65°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is 65°.

[0048] The material of artificial blood vessels is polylactic acid.

[0049] The inner and outer layers of the artificial blood vessel of the present invention are bionic, similar to the arrangement of natural blood vessel fibers, and are used to promote the adhesion, proliferation and differentiation of endothelial cells (inner layer) and smooth muscle cells (outer layer); while the middle layer is a disordered structure and is used to provide mechanical support.

[0050] Figure 2 4 is a cross-sectional view of the vascular wall after the artificial blood vessel is implanted into the human body, 4 is the vascular endothelial cells after implantation into the human body, and 5 is the vascular smooth muscle cells after implantation into the human body. Figure 2 Showing the growth of two types of cells on artificial blood vessels.

[0051] Example 2

[0052] A three-layer structured small-caliber artificial blood vessel, wherein the wall of the artificial blood vessel is composed of three layers, an inner layer 3 is an ordered fiber layer, a middle layer 2 is a disordered fiber layer, and an outer layer 1 is an ordered fiber layer.

[0053] The diameter of the inner fiber of the artificial blood vessel is 30 μm, the diameter of the middle fiber is 30 μm, and the diameter of the outer fiber is 30 μm; the distance between the inner and outer fibers is 300 μm.

[0054] The number of fiber layers of the inner and outer ordered fiber layers of the artificial blood vessel is 25.

[0055] The crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 60°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is 60°.

[0056] The material of the artificial blood vessel is a combination of polycaprolactone and lactide-caprolactone copolymer.

[0057] Example 3

[0058] A three-layer structured small-caliber artificial blood vessel, wherein the wall of the artificial blood vessel is composed of three layers, an inner layer 3 is an ordered fiber layer, a middle layer 2 is a disordered fiber layer, and an outer layer 1 is an ordered fiber layer.

[0059] The diameter of the inner fiber of the artificial blood vessel is 1 μm, the diameter of the middle fiber is 1 μm, and the diameter of the outer fiber is 1 μm; the distance between the inner and outer fibers is 250 μm.

[0060] The number of fiber layers of the inner and outer ordered fiber layers of the artificial blood vessel is 15.

[0061] The crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 60°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is 70°.

[0062] The artificial blood vessel material is a combination of lactide-caprolactone copolymer and polyurethane.

[0063] Example 4

[0064] The invention discloses a small-caliber artificial blood vessel with a three-layer structure. The wall of the artificial blood vessel is composed of three layers, the inner layer is an ordered fiber layer, the middle layer is a disordered fiber layer, and the outer layer is an ordered fiber layer.

[0065] The diameter of the inner fiber of the artificial blood vessel is 900nm, the diameter of the middle fiber is 150nm, and the diameter of the outer fiber is 800nm; the distance between the inner and outer fibers is 80μm.

[0066] The number of fiber layers of the inner and outer ordered fiber layers of the artificial blood vessel is 50.

[0067] The crossing angle of the fibers in the inner ordered fiber layer of the artificial blood vessel is 80°, and the crossing or circumferential orientation distribution angle of the fibers in the outer ordered fiber layer of the artificial blood vessel is -20°.

[0068] The material of the artificial blood vessel is lactide-caprolactone copolymer.

[0069] Example 5

[0070] A method for preparing a three-layer structured small-caliber artificial blood vessel is as follows: inner layer cross-distribution ordered near-field direct writing + middle layer disordered electrospinning + outer layer cross-distribution ordered near-field direct writing, specifically comprising the following steps:

[0071] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0072] 2) Preparation of the middle layer disordered electrospun fiber layer: dissolve the selected polymer material in a solvent to prepare an electrospinning solution, load it into a syringe, install it in an electrospinning device, select the inner diameter of the spinning nozzle, and set the spinning parameters (flow rate, voltage, receiving rod speed and distance from the needle to the receiving rod). Electrospinning is performed on the inner layer ordered fiber layer prepared in step 1) to finally obtain a middle layer disordered electrospun fiber layer.

[0073] 3) Preparation of outer cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the outer cross-distributed ordered fiber layer on the middle layer disordered fiber layer prepared in step 2).

[0074] 4) Demolding: The sample prepared in the above three steps is removed from the receiving rod to obtain the three-layer structure small-caliber artificial blood vessel.

[0075] The present invention introduces near-field direct writing technology to accurately construct an orderly stacked fiber structure of inner and outer layers, significantly promoting the infiltration and proliferation of vascular endothelial cells and vascular smooth muscle cells, thereby overcoming the limitations of traditional technology.

[0076] Advantages of the present invention:

[0077] 1. Enhanced structural performance: The middle random fiber layer of the present invention adopts finer fibers and an adjustable diameter / pore size design, which not only gives the artificial blood vessel good elasticity and compliance, making it more adaptable to complex physiological environments, but also improves its stability and durability in vivo.

[0078] 2. Promote blood vessel regeneration: The inner and outer layers of ordered fibers are stacked in an orderly manner at a specific angle, simulating the arrangement of collagen fibers in natural blood vessels of the human body. This design can accelerate the reconstruction and endothelialization of the smooth muscle layer, thereby effectively promoting the regeneration and repair of vascular tissue and improving the biocompatibility and functionality of artificial blood vessels.

[0079] 3. Safe material selection and simple preparation process: This product uses synthetic or natural degradable polymers as raw materials, which have good biocompatibility and ensure the safety and reliability of the product. At the same time, the preparation process is relatively simple, and no or only a small amount of organic solvent is required, which is environmentally friendly, reduces production costs, and improves production efficiency.

[0080] Example 6

[0081] like Figure 1 As shown, a method for preparing a three-layer structured small-caliber artificial blood vessel is as follows: inner layer cross-distribution ordered near-field direct writing + middle layer disordered electrospinning + outer layer circumferential orientation distribution ordered near-field direct writing.

[0082] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0083] 2) Preparation of the middle layer disordered electrospun fiber layer: dissolve the selected polymer material in a solvent to prepare an electrospinning solution, load it into a syringe, install it in an electrospinning device, select the inner diameter of the spinning nozzle, and set the spinning parameters (flow rate, voltage, receiving rod speed and distance from the needle to the receiving rod). Electrospinning is performed on the inner layer ordered fiber layer prepared in step 1) to finally obtain a middle layer disordered electrospun fiber layer.

[0084] 3) Preparation of outer layer circumferentially oriented ordered fiber layer with near-field direct writing: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and circumferential orientation distribution angle), start the program to complete the printing of the outer layer circumferentially oriented ordered fiber layer on the middle layer disordered fiber layer prepared in step 2).

[0085] 4) Demolding: The sample prepared in the above three steps is removed from the receiving rod to obtain the three-layer structure small-caliber artificial blood vessel.

[0086] Example 7

[0087] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises: inner layer cross-distribution ordered near-field direct writing + middle layer disordered near-field direct writing + outer layer cross-distribution ordered near-field direct writing.

[0088] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0089] 2) Preparation of middle-layer disordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, the distance between the needle and the receiving rod, the printing voltage and air pressure, write the printing path, start the program, and print on the inner ordered fiber layer prepared in step 1) to finally obtain the middle-layer disordered near-field direct writing fiber layer.

[0090] 3) Preparation of outer cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the outer cross-distributed ordered fiber layer on the middle layer disordered fiber layer prepared in step 2).

[0091] 4) Demolding: The sample prepared in the above three steps is removed from the receiving rod to obtain the three-layer structure small-caliber artificial blood vessel.

[0092] Example 8

[0093] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises: inner layer cross-distribution ordered near-field direct writing + middle layer disordered near-field direct writing + outer layer circumferential orientation distribution ordered near-field direct writing.

[0094] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0095] 2) Preparation of middle-layer disordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, the distance between the needle and the receiving rod, the printing voltage and air pressure, write the printing path, start the program, and print on the inner ordered fiber layer prepared in step 1) to finally obtain the middle-layer disordered near-field direct writing fiber layer.

[0096] 3) Preparation of outer layer circumferentially oriented ordered fiber layer with near-field direct writing: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and circumferential orientation distribution angle), start the program to complete the printing of the outer layer circumferentially oriented ordered fiber layer on the middle layer disordered fiber layer prepared in step 2).

[0097] 4) Demolding: The sample prepared in the above three steps is removed from the receiving rod to obtain the three-layer structure small-caliber artificial blood vessel.

[0098] Example 9

[0099] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises the following steps: preparing and heat-sealing an inner layer with cross-distribution and orderly near-field direct writing, a middle layer with disordered electrospinning, and an outer layer with cross-distribution and orderly near-field direct writing.

[0100] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0101] 2) Preparation of the middle layer disordered electrospinning fiber layer: The selected polymer material is dissolved in a solvent to prepare an electrospinning solution, which is loaded into a syringe and installed in an electrospinning device. The inner diameter of the spinning nozzle is selected, and the spinning parameters (flow rate, voltage, receiving rod speed and distance from the needle to the receiving rod) are set. Electrospinning is performed on the receiving rod to finally obtain a middle layer disordered electrospinning fiber layer.

[0102] 3) Preparation of outer cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the outer cross-distributed ordered fiber layer.

[0103] 4) Assembling and heat sealing: The disordered electrospun fiber layer obtained in step 2) is demolded from the receiving rod and placed on the ordered near-field direct writing fiber layer in step 1). Subsequently, the ordered near-field direct writing fiber layer obtained in step 3) is demolded from the receiving rod and placed on the disordered electrospun fiber layer in step 2). Finally, the three-layer structure is kept at 65°C for a period of time, and then demolded and removed after cooling to room temperature to obtain the small-caliber artificial blood vessel.

[0104] Example 10

[0105] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises the following steps: preparing and heat-sealing the inner layer by cross-distribution ordered near-field direct writing, the middle layer by disordered electrospinning, and the outer layer by circumferential orientation ordered near-field direct writing.

[0106] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0107] 2) Preparation of the middle layer disordered electrospinning fiber layer: The selected polymer material is dissolved in a solvent to prepare an electrospinning solution, which is loaded into a syringe and installed in an electrospinning device. The inner diameter of the spinning nozzle is selected, and the spinning parameters (flow rate, voltage, receiving rod speed and distance from the needle to the receiving rod) are set. Electrospinning is performed on the receiving rod to finally obtain a middle layer disordered electrospinning fiber layer.

[0108] 3) Preparation of outer layer circumferentially oriented ordered fiber layer by near-field direct writing: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and circumferential orientation distribution angle), and start the program to complete the printing of the outer layer circumferentially oriented ordered fiber layer.

[0109] 4) Assembling and heat sealing: The disordered electrospun fiber layer obtained in step 2) is demolded from the receiving rod and placed on the ordered near-field direct writing fiber layer in step 1). Subsequently, the ordered near-field direct writing fiber layer obtained in step 3) is demolded from the receiving rod and placed on the disordered electrospun fiber layer in step 2). Finally, the three-layer structure is kept at 65°C for a period of time, and then demolded and removed after cooling to room temperature to obtain the small-caliber artificial blood vessel.

[0110] Embodiment 11

[0111] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises the following steps: preparing and heat-sealing an inner layer with cross-distribution ordered near-field direct writing, a middle layer with disordered near-field direct writing, and an outer layer with cross-distribution ordered near-field direct writing respectively.

[0112] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0113] 2) Preparation of the middle layer disordered near-field direct writing fiber layer: The selected polymer material is loaded into the barrel of the extrusion 3D printer, the inner diameter of the needle is selected, the barrel temperature, the needle temperature, the distance between the needle and the receiving rod, the printing voltage and air pressure are set, the printing path is written, the program is started, and printing is performed on the receiving rod to finally obtain the middle layer disordered near-field direct writing fiber layer.

[0114] 3) Preparation of outer cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the outer cross-distributed ordered fiber layer.

[0115] 4) Assembling and heat sealing: demoulding the disordered near-field direct writing fiber layer obtained in step 2) from the receiving rod, and putting it on the ordered near-field direct writing fiber layer in step 1). Subsequently, demoulding the ordered near-field direct writing fiber layer obtained in step 3) from the receiving rod, and putting it on the disordered near-field direct writing fiber layer in step 2). Finally, keep the temperature at 65°C for a period of time, cool to room temperature, demould and remove to obtain the three-layer structure small-caliber artificial blood vessel.

[0116] Example 12

[0117] A method for preparing a three-layer structured small-caliber artificial blood vessel comprises the following steps: preparing and heat-sealing an inner layer with cross-distribution ordered near-field direct writing, a middle layer with disordered near-field direct writing, and an outer layer with circumferential orientation ordered near-field direct writing respectively.

[0118] 1) Preparation of inner cross-distributed ordered near-field direct writing fiber layer: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and crossing angle), and start the program to complete the printing of the inner cross-distributed ordered fiber layer.

[0119] 2) Preparation of the middle layer disordered near-field direct writing fiber layer: The selected polymer material is loaded into the barrel of the extrusion 3D printer, the inner diameter of the needle is selected, the barrel temperature, the needle temperature, the distance between the needle and the receiving rod, the printing voltage and air pressure are set, the printing path is written, the program is started, and printing is performed on the receiving rod to finally obtain the middle layer disordered near-field direct writing fiber layer.

[0120] 3) Preparation of outer layer circumferentially oriented ordered fiber layer by near-field direct writing: Load the selected polymer material into the barrel of the extrusion 3D printer, select the inner diameter of the needle used, set the barrel temperature, needle temperature, distance between the needle and the receiving rod, printing voltage and air pressure, write the printing path according to the ordered layer design requirements (determine the fiber diameter, fiber spacing and circumferential orientation distribution angle), and start the program to complete the printing of the outer layer circumferentially oriented ordered fiber layer.

[0121] 4) Assembling and heat sealing: demoulding the disordered near-field direct writing fiber layer obtained in step 2) from the receiving rod, and putting it on the ordered near-field direct writing fiber layer in step 1). Subsequently, demoulding the ordered near-field direct writing fiber layer obtained in step 3) from the receiving rod, and putting it on the disordered near-field direct writing fiber layer in step 2). Finally, keep the temperature at 65°C for a period of time, cool to room temperature, demould and remove to obtain the three-layer structure small-caliber artificial blood vessel.

[0122] The three-layer structure of the present invention is a small-caliber artificial blood vessel and its preparation method:

[0123] 1. Design of a novel three-layer structure with small caliber artificial blood vessels

[0124] The invention provides a small-caliber artificial blood vessel with a unique three-layer structure, in which the inner and outer layers are ordered fiber layers, and the middle layer is a disordered fiber layer. This design is intended to simulate the complex structure of natural blood vessels and improve the biocompatibility and functionality of artificial blood vessels.

[0125] 2. Diversity of preparation methods

[0126] The inner and outer ordered fiber layers are prepared by melt near-field direct writing technology, which ensures the precise arrangement of the fibers; the middle disordered fiber layer can be prepared by melt near-field direct writing or electrospinning technology, providing flexible process options to meet different performance requirements.

[0127] 3. Accurate fiber size and precise control

[0128] The diameter and spacing of the inner and outer fibers, as well as the number of inner and outer ordered fiber layers, are strictly controlled to ensure the accuracy and consistency of the artificial blood vessel structure.

[0129] 4. Specific fiber orientation

[0130] The inner and outer ordered fiber layers have specific cross- or circumferential orientation distribution angles designed to mimic the mechanical properties, blood flow characteristics, and biological properties of natural blood vessels.

[0131] 5. Selection of biodegradable materials

[0132] Biodegradable materials including synthetic polymers (such as polylactic acid, polycaprolactone, lactide-caprolactone copolymer, polydioxanone, lactide-glycolide copolymer and polyurethane, etc.), natural polymers (such as chitosan, hyaluronic acid, alginate, cellulose, starch, chondroitin sulfate, gelatin, silk fibroin, collagen, fibrin, serum albumin and elastin, etc.) or combinations thereof are used, so that the artificial blood vessels can be gradually absorbed by the body after completing their replacement function, thereby reducing long-term foreign body reactions.

[0133] 6. Flexible manufacturing process

[0134] Two manufacturing processes are provided: one-piece molding and separate preparation followed by assembly and heat sealing. One-piece molding ensures close bonding between layers by continuously printing three layers in the same process, while separate preparation followed by assembly and heat sealing provides more processing flexibility and material selection space.

[0135] The present invention utilizes a combination of near-field direct writing 3D printing technology and electrospinning technology to achieve precise construction of complex structures of small-caliber artificial blood vessels.

[0136] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-layer structured small-caliber artificial blood vessel, characterized in that: The wall of the artificial blood vessel is composed of three layers, the inner layer (3) is an ordered fiber layer, the middle layer (2) is a disordered fiber layer, and the outer layer (1) is an ordered fiber layer.

2. The three-layer small-caliber artificial blood vessel according to claim 1, characterized in that: The fiber diameter of the inner layer (3) is 3nm-30μm, the fiber diameter of the middle layer (2) is 3nm-30μm, and the fiber diameter of the outer layer (1) is 3nm-30μm; the fiber spacing between the inner layer (3) and the outer layer (1) is 5μm-300μm.

3. The three-layer small-caliber artificial blood vessel according to claim 1 or 2, characterized in that: The number of fiber layers of the inner layer (3) and the outer layer (1) of the artificial blood vessel is 2 to 50.

4. The three-layer small-caliber artificial blood vessel according to claim 1 or 2, characterized in that: The fibers of the ordered fiber layer of the inner layer (3) of the artificial blood vessel have a specific crossing angle of -20° to 80°; the fibers of the ordered fiber layer of the outer layer (1) of the artificial blood vessel have a specific crossing or circumferential orientation distribution angle of -20° to 80°.

5. The three-layer small-caliber artificial blood vessel according to claim 4, characterized in that: The crossing angle of the fibers in the inner layer (3) of the artificial blood vessel is 65°, and the crossing or circumferential orientation distribution angle of the fibers in the outer layer (1) of the artificial blood vessel is 65°.

6. The three-layer small-caliber artificial blood vessel according to claim 1, characterized in that: The artificial blood vessel is biodegradable, and the material is selected from synthetic polymers, natural polymers or a combination thereof; The synthetic polymers include, but are not limited to, polylactic acid, polycaprolactone, lactide-caprolactone copolymer, polydioxanone, lactide-glycolide copolymer, and polyurethane; The natural polymers include, but are not limited to, chitosan, hyaluronic acid, alginate, cellulose, starch, chondroitin sulfate, gelatin, silk fibroin, collagen, fibrin, serum albumin, and elastin.

7. The three-layer small-caliber artificial blood vessel according to claim 1, characterized in that: The artificial blood vessel may be surface-modified, and the modification materials include polymers, inorganic nanomaterials, growth factors and other substances; Polymers include, but are not limited to, polyacrylonitrile, polydimethylsiloxane, polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone, and polystyrene; Inorganic nanomaterials include, but are not limited to, silicon dioxide, carbon nanotubes, titanium dioxide, graphene, and silver nanoparticles; Growth factors include, but are not limited to, epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, keratinocyte growth factor, and insulin-like growth factor; Other substances include, but are not limited to, natural polyphenols, polydopamine, biological enzymes, surfactants, antimicrobial agents and silane coupling agents.

8. The three-layer small-caliber artificial blood vessel according to claim 1, characterized in that: The artificial blood vessels can be loaded with drugs or bioactive substances, including antibacterial agents, anti-inflammatory drugs, analgesics, antiviral drugs, anti-tumor drugs, natural flavonoids or polyphenols, growth factors, antioxidants, polypeptides or proteins, and gene drugs; Antimicrobial agents include but are not limited to antibiotics and antimicrobial peptides; anti-inflammatory drugs include but are not limited to glucocorticoids and non-steroidal anti-inflammatory drugs; analgesics include but are not limited to ibuprofen and acetaminophen; antiviral drugs include but are not limited to acyclovir and oseltamivir; anti-tumor drugs include but are not limited to paclitaxel and doxorubicin; natural flavonoids or polyphenols include but are not limited to quercetin and tea polyphenols; growth factors include but are not limited to epidermal growth factor and vascular endothelial growth factor; antioxidants include but are not limited to vitamin C and vitamin E; polypeptides or proteins include but are not limited to insulin and growth hormone; gene drugs include but are not limited to DNA and siRNA.

9. A method for preparing a three-layer small-caliber artificial blood vessel according to any one of claims 1 to 8, characterized in that: The inner layer (3) and the outer layer (1) are prepared by melt near-field direct writing, and the middle layer (2) is prepared by melt near-field direct writing or electrostatic spinning.

10. The preparation method according to claim 9, characterized in that: The preparation method comprises integral molding or separate preparation of the inner layer (3), the middle layer (2), and the outer layer (1) structures and then assembling and heat-sealing them.

11. The preparation method according to claim 10, characterized in that: The one-piece forming comprises the following steps: using near-field direct writing 3D printing technology to print an inner layer (3) of ordered fiber layer on a metal receiving rod of a specific diameter, then using near-field direct writing 3D printing technology or electrostatic spinning technology to prepare a middle layer (2) of disordered fiber layer on the inner layer (3), and finally using near-field direct writing 3D printing technology to print an outer layer (1) of ordered fiber layer on the middle layer (2).

12. The preparation method according to claim 10, characterized in that: The method for separately preparing the inner layer (3), the middle layer (2), and the outer layer (1) structures and then assembling and heat-sealing them comprises the following steps: using near-field direct writing 3D printing technology to print the inner layer (3) and the outer layer (1) ordered fiber layer respectively, using near-field direct writing 3D printing technology or electrostatic spinning technology to prepare the middle layer (2) disordered fiber layer, and then sleeve-jointing the three-layer structure and performing a heat bonding treatment.

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