Multifunctional composite pleural repair patch and methods of making

Abstract

The application discloses a multifunctional composite pleura repair patch which is composed of three functional layers from outside to inside, namely, a hydrogel layer, an electrospun fiber layer and a direct writing scaffold layer, the three functional layers are prepared by different materials and processing techniques, and each of the three functional layers bears a part of functions, 1) the hydrogel layer is formed by photo-crosslinking of a polymer solution with biological adhesion, has a compact structure and can provide good air tightness; 2) the electrospun fiber layer has a uniform and fine nanoscale pore structure, can simulate an extracellular matrix, intercept cells and provide a substrate for growth of the cells; and 3) the direct writing scaffold layer can promote adhesion and ingrowth of cells and guide the growth orientation of the cells.

Description

Technical Field

[0001] This invention relates to the field of tissue engineering materials technology, specifically a multifunctional composite pleural repair patch and its preparation method. Background Technology

[0002] The pleura is a serous membrane composed of mesothelium and a thin layer of connective tissue. The visceral pleura covers the outer surface of the lungs, while the parietal pleura covers the inner surface of the pleural cavity. The visceral and parietal pleura are connected only at the lung roots where the bronchi and pulmonary vessels enter the lungs, thus forming a completely closed cavity around each lung, called the pleural cavity. Under normal circumstances, the pleural cavity contains no gas, and the pressure is always lower than atmospheric pressure, which helps maintain the expansion of the lungs and trachea, ensuring lung ventilation. However, lung diseases, external trauma, and surgical procedures can all cause defects in the pleura, allowing gas or tissue fluid to enter the pleural cavity, leading to lung diseases such as pneumothorax, hemothorax, or empyema. The negative pressure environment of the pleural cavity is disrupted, causing difficulty breathing, prolonged recovery time, and in severe cases, even shock and suffocation, endangering life.

[0003] Traditional treatments for pleural defects involve using physical or chemical methods to fix the pleura at the defect site, causing adhesion between the visceral and parietal layers to re-close the pleural cavity, while simultaneously using closed pleural drainage to remove effusion or pneumothorax. However, chemical fixation methods often cause pain and infection, while physical methods such as burning and scraping can cause secondary damage to normal tissue. Furthermore, adhesions in the pleura increase the difficulty of subsequent surgeries and raise the risk of postoperative bleeding. Therefore, repair patches are now preferred for treating pleural defects.

[0004] Currently, patch materials used for pleural repair are mainly divided into two categories: one is synthetic biomaterial patches based on polymers, such as absorbable polyglycolic acid (PEG) repair materials. However, these patches lack bioactivity and have a single function, only providing mechanical reinforcement. Due to their large pore size, they cannot provide a seal when used alone and must be used in conjunction with other bio-adhesives to form a dense repair layer. The other category consists of biomaterial patches obtained by processing natural tissues. Currently, decellularized porcine and bovine pericardium and autologous temperature-responsive cell membrane patches are relatively mature applications. These materials have good biocompatibility, but their preparation process is complex, costly, and generally has weak mechanical strength. Therefore, how to prepare a composite patch that is low-cost, has suitable mechanical strength, good sealing properties, and good biocompatibility has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] One objective of this invention is to develop a low-cost patch with suitable mechanical strength, good sealing properties, and biocompatibility for pleural repair, overcoming the shortcomings of existing patches. To this end, this invention proposes and designs a multifunctional composite pleural repair patch composed of three functional layers: a hydrogel layer, an electrospun fiber layer, and a direct-write scaffold layer, from the outside to the inside. Figure 1 As shown. These three functional layers are made of different materials and processing techniques, and each performs a portion of the functions:

[0006] 1) The hydrogel layer is formed by photocrosslinking of a bioadhesive polymer solution, resulting in a dense structure that provides excellent airtightness. Simultaneously, it can be linked to proteins on the pleural tissue surface via hydrogen bonds or covalent bonds through grafted functional groups, thus fixing the entire patch to the affected area.

[0007] 2) The electrospun fiber layer is a nanofiber membrane made by electrospinning a spinning solution prepared from water-soluble polymers and their crosslinking agents. This layer has a uniform and fine nanoscale pore structure, which can simulate the extracellular matrix, trap cells and provide a substrate for their growth.

[0008] 3) The direct-write scaffold layer is printed from low-melting-point biopolymers using a melt near-field direct-write process. It has a controllable three-dimensional structure, micron-sized fiber diameter, and pores similar to those at the cell scale, which can promote cell adhesion and ingrowth and guide the orientation of their growth.

[0009] Another object of the present invention is to provide a method for preparing a multifunctional composite pleural repair patch, comprising the following steps:

[0010] 1) Using a mixed solution of polyvinyl alcohol, methacrylic anhydride gelatin and distilled water as the spinning solution, electrospinning was performed to obtain an uncrosslinked nanofiber membrane;

[0011] 2) The nanofiber membrane obtained in step 1) is subjected to glutaraldehyde crosslinking treatment to obtain a crosslinked electrospun fiber layer;

[0012] 3) Using molten polycaprolactone as the material, a direct-write scaffold is printed on any one side of the cross-linked nanofiber membrane in step 2) through near-field direct writing to obtain a bilayer composite patch;

[0013] 4) Weigh out acrylic acid, gelatin, N-hydroxysuccinimide acrylate, methacrylic anhydride gelatin, photoinitiator and sodium hydroxide, and add an appropriate amount of distilled water to prepare a hydrogel precursor solution;

[0014] 5) Pour the precursor solution from step 4) into a PDMS mold and perform photocuring. Then add the composite patch prepared in step 3), and combine the side with the nanofiber membrane with the hydrogel. After complete drying, a multifunctional composite pleural repair patch can be obtained. After sterilization, it is refrigerated for later use.

[0015] In step 1), the mass concentration of polyvinyl alcohol is 8-12%, and the mass of methacrylic anhydride gelatin is 1-10% of the mass of polyvinyl alcohol.

[0016] Preferably, in step 1), the liquid supply flow rate for electrospinning is 0.2–0.6 ml / h, the spinning voltage is 10–20 kV, the printing speed is 300–1500 mm / min, and the spinning height is 10–15 cm.

[0017] In step 2), the concentration of glutaraldehyde is 1% to 2.5%, the solvent is acetone, ethanol or other reagents that do not dissolve polyvinyl alcohol and methacrylic anhydride gelatin, and the crosslinking time is 4 to 24 hours.

[0018] Preferably, the polycaprolactone in step 3) has a molecular weight of 80,000 Da and a heating temperature of 70–120°C.

[0019] In step 3), the near-field direct writing feed air pressure is 0.02-0.1 MPa, the printing speed is 500-2000 mm / min, the direct writing voltage is 2-6 kV, and the distance from the printhead to the collection plate is 2-5 mm.

[0020] Ideally, the mass concentration of each component in the hydrogel precursor solution described in step 4) is 30% acrylic acid, 10% gelatin, 1% N-hydroxysuccinimide acrylate, 0.1% methacrylic anhydride gelatin, and 0.2-0.5% photoinitiator. The pH of the hydrogel precursor solution is adjusted to neutral with sodium hydroxide.

[0021] Preferably, the photoinitiator is lithium phenyl-2,4,6-trimethylbenzoyl phosphate (LAP).

[0022] The photocuring in step 5) is performed under ultraviolet light, and the energy of the ultraviolet light is 15-20 mW / cm². 2 .

[0023] The crosslinking time for photocuring in step 5) is 30 to 300 seconds.

[0024] The beneficial effects of this invention are as follows: The composite pleural repair patch prepared by this invention comprises a hydrogel layer, an electrospun fiber layer, and a direct-write scaffold layer. The hydrogel layer is formed by photocrosslinking of a bioadhesive polymer solution, resulting in a dense structure that provides excellent airtightness. Simultaneously, it can connect with proteins on the pleural tissue surface via hydrogen bonds or covalent bonds through grafted functional groups, thus fixing the entire patch to the affected area. The electrospun fiber layer is a nanofiber membrane made by electrospinning a spinning solution formulated with a water-soluble polymer and its crosslinking agent. This layer has a uniform and fine nanoscale porous structure, capable of mimicking the extracellular matrix, trapping cells, and providing a substrate for their growth. The direct-write scaffold layer is printed from low-melting-point biopolymers using a melt near-field direct-write process. It has a controllable three-dimensional structure, micron-sized fiber diameters, and pores similar to those at the cell scale, promoting cell adhesion and ingrowth, and guiding their growth orientation.

[0025] This invention combines two electrohydrodynamic printing processes, electrospinning and near-field direct writing, to fabricate two tissue engineering scaffolds with different scales and microstructures. The electrospun fiber layer has an isotropic fiber structure and nanoscale pores that cells cannot penetrate, thus trapping settled cells and providing a substrate for their growth. In contrast, the direct-written scaffold layer has coarser fibers with pore sizes similar to those of cells, providing three-dimensional space for adhesion and spread on the scaffold.

[0026] The electrospinning solution uses water-soluble polymers, and the near-field direct writing uses molten materials, avoiding the introduction of toxic solvents. This not only makes the preparation process simple, safe, and environmentally friendly, but also ensures that the product is non-biologically toxic.

[0027] The hydrogel layer, composed of gelatin and polyacrylic acid forming a double cross-linked network, exhibits excellent water absorption. Furthermore, the grafted NHS groups can react with primary amines under physiological conditions to form stable amide bonds, allowing the patch to be fixed to the affected area without sutures. In summary, the composite pleural repair patch prepared by this invention is characterized by low cost, suitable mechanical strength, good sealing properties, and biocompatibility. Attached Figure Description

[0028] Figure 1 This is a design concept diagram of the present invention.

[0029] From top to bottom, they are a hydrogel layer, an electrospun fiber layer, and a direct-write scaffold layer.

[0030] Figure 2 This is a flowchart illustrating the preparation process of the present invention.

[0031] Figure 3 The chemical equation for the bioadhesive properties of the gel layer.

[0032] Figure 4 SEM images of the direct-write scaffold layer, electrospun fiber layer, and composite patch.

[0033] (a) Direct writing scaffold layer, (b) Electrospun fiber layer, (c) Two-layer composite with electrospun fiber layer on top, (d) Two-layer composite with electrospun fiber layer on the bottom, (e) Three-layer composite with the junction of electrospun fiber layer and hydrogel layer, (f) Cross-sectional view of three-layer composite.

[0034] Figure 5 The images are photographs of the actual product of this invention. The left image shows the product pasted on a collagen casing, and the right image shows it pasted on the back of a normal person's hand. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following specific embodiments.

[0036] Example 1

[0037] (1) Dissolve 1g of polyvinyl alcohol and 0.5g of methacrylic anhydride gelatin in 10ml of distilled water and stir for 8h. Pour the completely dispersed spinning solution into a 10ml syringe and perform electrospinning. The spinning voltage is 13kV, the spinning height is 15cm, the liquid supply flow rate is 0.4ml / h, and the uncrosslinked nanofiber membrane is obtained after spinning for 2h.

[0038] (2) Remove the nanofiber membrane obtained in step (1) from the collection plate, immerse it in a pre-prepared acetone solution containing 1% glutaraldehyde and 0.01% hydrochloric acid, seal the container, and take it out after 4 hours to obtain the electrospun fiber layer after liquid crosslinking.

[0039] (3) Heat polycaprolactone to 90°C and print a direct-write template on any single side of the cross-linked nanofiber membrane in step (2) using near-field direct writing. The feed pressure is 0.06 MPa, the printing speed is 2000 mm / min, the direct-write voltage is 5 kV, the distance from the nozzle to the collection plate is 4 mm, and the printing spacing is 100 μm for a grid pattern, repeated 20 times.

[0040] (4) Take 1.5g acrylic acid, 0.5g gelatin, 0.05g N-hydroxysuccinimide acrylate, 0.005g methacrylic anhydride gelatin, 0.02g photoinitiator and 0.8g sodium hydroxide and dissolve them in 5ml distilled water. Stir for 8h to prepare a hydrogel precursor solution.

[0041] (5) Pour the precursor solution from step (4) into a PDMS mold and perform photocuring for 2 minutes. Then add the composite patch prepared in step (3), combine the side with the nanofiber membrane with the hydrogel, and allow it to dry naturally for 12 hours to obtain a multifunctional composite pleural repair patch.

[0042] Example 2

[0043] (1) Dissolve 0.5g of polyvinyl alcohol and 0.5g of methacrylic anhydride gelatin in 5ml of distilled water and stir for 8h. Pour the completely dispersed spinning solution into a 10ml syringe and perform electrospinning. The spinning voltage is 16kV, the spinning height is 10cm, the liquid supply flow rate is 0.5ml / h, and the uncrosslinked nanofiber membrane is obtained after spinning for 0.5h.

[0044] (2) Remove the nanofiber membrane obtained in step (1) from the collection plate, prepare an acetone solution containing 2% glutaraldehyde and 0.01% hydrochloric acid in advance, place a platform in the container with the upper surface above the liquid surface for placing the fiber membrane, seal the container, and take it out after 12 hours to obtain the electrospun fiber layer after steam crosslinking.

[0045] (3) Heat polycaprolactone to 90°C and print a direct-write template on any single side of the cross-linked nanofiber membrane in step (2) using near-field direct writing. The feed gas pressure is 0.06 MPa, the printing speed is 500 mm / min, the direct-write voltage is 4 kV, the distance from the nozzle to the collection plate is 3 mm, and the printing spacing is a grid pattern of 50 μm, repeated 20 times.

[0046] (4) Take 1.5g acrylic acid, 0.5g gelatin, 0.05g N-hydroxysuccinimide acrylate, 0.005g methacrylic anhydride gelatin, 0.02g photoinitiator and 0.8g sodium hydroxide and dissolve them in 5ml distilled water. Stir for 8h to prepare a hydrogel precursor solution.

[0047] (5) Pour the precursor solution from step (4) into a PDMS mold and perform photocuring for 30 seconds. Then add the composite patch prepared in step (3), combine the side with the nanofiber membrane with the hydrogel, and allow it to dry naturally for 12 hours to obtain a multifunctional composite pleural repair patch.

[0048] The above are merely exemplary embodiments of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent exchange or substitution fall within the scope of protection of the present invention.

Claims

1. A method for preparing a multifunctional composite pleural repair patch, characterized in that, Includes the following steps: 1) Using a mixed solution of polyvinyl alcohol, methacrylic anhydride gelatin and distilled water as the spinning solution, electrospinning was performed to obtain an uncrosslinked nanofiber membrane; 2) The nanofiber membrane obtained in step 1) is subjected to glutaraldehyde crosslinking treatment to obtain a crosslinked electrospun fiber layer; 3) Using molten polycaprolactone as the material, a direct-write scaffold is printed on any one side of the cross-linked nanofiber membrane in step 2) through near-field direct writing to obtain a bilayer composite patch; 4) Weigh out acrylic acid, gelatin, N-hydroxysuccinimide acrylate, methacrylic anhydride gelatin, photoinitiator, and sodium hydroxide, and add an appropriate amount of distilled water to prepare a hydrogel precursor solution; the mass concentration of each component in the hydrogel precursor solution is 30% acrylic acid, 10% gelatin, 1% N-hydroxysuccinimide acrylate, 0.1% methacrylic anhydride gelatin, and 0.2-0.5% photoinitiator; adjust the pH of the hydrogel precursor solution to neutral with sodium hydroxide; 5) Pour the precursor solution from step 4) into a PDMS mold and perform photocuring. Then add the composite patch prepared in step 3) and combine the side with the nanofiber membrane with the hydrogel. After it is completely dried, a multifunctional composite pleural repair patch can be obtained. After sterilization, it is refrigerated for later use. In step 1), the mass concentration of polyvinyl alcohol is 8-12%, and the mass of methacrylic anhydride gelatin is 1-10% of the mass of polyvinyl alcohol. In step 2), the concentration of glutaraldehyde is 1% to 2.5%, the solvent is acetone, ethanol or other reagents that do not dissolve polyvinyl alcohol and methacrylic anhydride gelatin, and the crosslinking time is 4 to 24 hours. In step 3), the near-field direct writing feed air pressure is 0.02-0.1MPa, the printing speed is 500-2000mm / min, the direct writing voltage is 2-6kV, and the distance from the nozzle to the collection plate is 2-5mm. The photocuring in step 5) is performed under ultraviolet light, and the energy of the ultraviolet light is 15-20 mW / cm². 2 In step 5), the crosslinking time for photocuring is 30 to 300 seconds.

2. The preparation method of the multifunctional composite pleural repair patch according to claim 1, characterized in that, In step 1), the electrospinning liquid flow rate is 0.2–0.6 ml / h, the spinning voltage is 10–20 kV, the printing speed is 300–1500 mm / min, and the spinning height is 10–15 cm.

3. The preparation method of the multifunctional composite pleural repair patch according to claim 2, characterized in that, In step 3), the polycaprolactone has a molecular weight of 80,000 Da and a heating temperature of 70–120°C.

4. The preparation method of the multifunctional composite pleural repair patch according to claim 3, characterized in that, The photoinitiator is lithium phenyl-2,4,6-trimethylbenzoyl phosphate (LAP).

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