Double-layer gelatin matrix hemostatic material and preparation method thereof

Abstract

The invention provides a double-layer gelatin matrix hemostatic material and a preparation method thereof. The material is composed of a rapid gel layer formed by high-concentration gelatin and a cross-linked gelatin particle composite layer. The high-concentration gelatin layer can quickly form a physical barrier to realize quick initial hemostasis; the cross-linked gelatin particle composite layer remarkably enhances the mechanical strength of the material through a multi-stage cross-linked structure, and meanwhile, the porous structure can efficiently absorb percolate to accelerate the hemostasis process. Due to the biocompatibility, biodegradability and histocompatibility of the natural gelatin, wound healing can be promoted, and the natural gelatin can be completely absorbed finally. The hemostatic material provided by the invention is rapid in hemostasis, excellent in mechanical property and good in biocompatibility, and has a wide application prospect in the fields of wound first aid, surgical hemostasis and the like.

Description

Technical Field

[0001] The invention relates to the field of absorbable hemostatic materials, and in particular to a double-layer gelatin matrix hemostatic material and a preparation method thereof. Background Art

[0002] In modern medicine, especially in surgical operations and battlefield emergency treatment, rapid and effective hemostasis is the key to saving lives. Traditional hemostasis methods, such as gauze packing, electrocoagulation and suturing, often have limitations, especially when dealing with extensive exudative bleeding or difficult-to-reach bleeding points. New hemostatic materials can not only provide more effective hemostasis, but also have multiple functions such as promoting wound healing and reducing the risk of infection.

[0003] The development of new hemostatic materials mainly focuses on the following aspects: 1. Innovative application of materials: such as cellulose, starch, collagen and gelatin, these natural materials have good biocompatibility and biodegradability. For example, porous gelatin sponge can promote blood coagulation by enhancing the adhesion and aggregation of platelets.

[0004] 2. Multifunctional integrated design: Hemostatic materials are not only required to have good hemostatic effects, but also to pursue multiple functions such as antibacterial and promoting tissue regeneration. For example, the hemostatic sponge based on gelatin and sodium alginate is 2+ The cross-linked and freeze-dried preparation not only has a good hemostatic effect, but also has the ability to promote wound healing.

[0005] 3. Bioabsorbability: Absorbable hemostatic materials can be naturally absorbed by the body after completing the hemostatic task, avoiding the risk of secondary surgery. For example, the cross-linked gelatin hemostatic sponge, which is easy to prepare, not only has a good hemostatic effect, but also has excellent properties such as good biocompatibility.

[0006] Research on hemostatic materials for clinical applications pays more attention to the biocompatibility, hemostatic efficiency and multifunctionality of the materials, in order to provide safer and more effective hemostatic solutions for clinical use. Summary of the invention

[0007] The present invention aims to provide a novel double-layer gelatin matrix hemostatic material, which significantly improves hemostatic efficiency, enhances biocompatibility and biodegradability, and has the additional function of promoting wound healing by optimizing structural design and material selection.

[0008] In view of the shortcomings of the prior art, the solutions provided by the present invention include: The double-layer gelatin matrix hemostatic material of the present invention comprises: a first layer is a matrix layer formed by air-drying a 5-10% high-concentration gelatin solution, with a thickness of 20-100 μm; a second layer is a foam layer formed by mixing a 0.5-1% gelatin solution with cross-linked gelatin particles; after the two layers of materials are compounded, freeze-dried and subjected to secondary thermal cross-linking to obtain a multi-level cross-linking structure.

[0009] A film made of 5-10% high-concentration gelatin solution dried in the shade is used as the first layer to quickly form a gel membrane barrier, effectively preventing blood loss; cross-linked gelatin particles that can absorb hemostatic fluid gelatin are dispersed in a low-concentration 0.5-1% gelatin solution, and after freeze-drying, a porous foam structure is formed, that is, the cross-linked gelatin particles are distributed in the porous foam structure, forming the second layer. The multi-level structural cross-linking technology is used to improve the mechanical strength and stability of the gelatin foam layer, and enhance the durability and practicality of the material. This multi-level structure not only ensures the stability of the structure, but also provides sufficient hemostatic reaction sites, which can effectively and quickly absorb blood, enrich platelets, and trigger the coagulation cascade process, achieving a rapid hemostatic effect. Through freeze-drying and secondary vacuum cross-linking drying technology, the moisture content is greatly reduced, and the storage stability and field applicability of the material are improved.

[0010] In this double-layer gelatin matrix hemostatic material, the two layers have different degrees of cross-linking, which affects their degradation rate and mechanical properties.

[0011] (1) Degradation of highly cross-linked layers The film formed by the high-concentration gelatin solution has a tighter molecular structure. After vacuum heat treatment, a high-crosslinking layer is formed. Since more chemical crosslinks are formed between gelatin molecules, these crosslinks increase the stability of the molecules and resist enzymatic hydrolysis in the body. The degradation rate of this layer is relatively slow because it is difficult for biological enzymes to penetrate the dense crosslinking network to cut off the gelatin molecular chain. The high-crosslinking layer maintains its structural integrity for a longer period of time during the degradation process, providing continuous support and protection for the wound.

[0012] (2) Degradation of low cross-linking layer The foam part formed by low-concentration gelatin forms a low-crosslinking layer. The chemical crosslinking bonds between gelatin molecules in the low-crosslinking layer are less, so it is easier for biological enzymes to approach and cut the molecular chains. The degradation rate of this layer is relatively fast, allowing the material to be absorbed and removed by the organism more quickly. The fast-degrading low-crosslinking layer helps reduce long-term foreign body reactions and promote early wound healing.

[0013] (3) Degradation characteristics of the double-layer structure There are also cross-linked gelatin particles with a high degree of cross-linking in the gelatin foam layer. After a secondary cross-linking process, these cross-linked gelatin particles can serve as structural support in the double-layer gelatin matrix hemostatic material, while the low-cross-linking layer provides initial hemostasis and biocompatibility. Over time, the low-cross-linking layer begins to degrade first and gradually loses its structural integrity, while the high-cross-linking layer maintains its structure and function for a longer period of time. This design allows the material to provide the necessary hemostasis and protection functions in the early stages, while ensuring that the material can be gradually absorbed by the organism in the long term, improving the compatibility of the material with tissue regeneration and reducing the risk of long-term complications.

[0014] Experimental data showed that the low cross-linking layer had a higher water absorption and swelling rate, which may be due to its rapid degradation leading to rapid changes in the material structure. The high cross-linking layer has relatively low water absorption and swelling rates due to its stability, which allows it to maintain structural integrity for a long time even after absorbing water. The degradation process of the double-layer gelatin matrix hemostatic material is jointly determined by two layers of gelatin with different cross-linking degrees. The highly cross-linked part provides long-lasting structural support, while the low cross-linking layer allows rapid bioabsorption and wound healing. This structural design enables the material to meet the needs of hemostasis and tissue repair over different time periods.

[0015] The preparation method of the double-layer gelatin matrix hemostatic material of the present invention comprises the following steps: (1) Preparation of gelatin solution Prepare 5~10% and 0.5~1% gelatin solutions, and dissolve by heating and stirring in a 50~60℃ water bath.

[0016] (2) Preparation of the bottom matrix A 5-10% gelatin solution was poured into a PTFE mold, which was treated to be hydrophilic and then dried in the shade to form the first layer of matrix.

[0017] (3) Preparation of cross-linked gelatin particles The freeze-dried gelatin sponge is cross-linked at high temperature in vacuum and then mechanically crushed and sieved to obtain particles with a particle size range of 50 to 300 mesh, namely cross-linked gelatin particles, which are also one of the main materials of absorbable hemostatic fluid gelatin. CN116251227B discloses a method for preparing an absorbable hemostatic fluid gelatin material, and the prepared fluid gelatin product has the advantage of low secondary liquid absorption expansion rate. The powder dosage form of fluid gelatin can be used as the above-mentioned cross-linked gelatin particles.

[0018] (4) Preparation of upper foam The cross-linked gelatin particles are mixed with 0.5-1% gelatin solution, mixed evenly by a syringe, squeezed into a mold, and injected into the mold to form a second layer of foam. The low-concentration gelatin solution acts as an adhesive, which can bond the cross-linked gelatin particles together and improve the stability of the double-layer gelatin structure. The mixing ratio of the cross-linked gelatin particles and the gelatin solution is preferably 1:4 to 1:10. The mixing method includes a foaming process, that is, the cross-linked gelatin particle powder is loaded into a syringe, excess air is discharged, and then a predetermined amount of gelatin solution is loaded into another syringe, and the two syringes are connected by a Luer connector, and pushed against each other to mix evenly to obtain a foamed gelatin paste; the foamed gelatin paste is squeezed into the mold, and the thickness of the paste is adjusted using a gasket and flattened.

[0019] (5) Freezing and freeze-drying The mold containing the double-layer gelatin structure is frozen at -20℃ or lower for more than 2 hours, and then freeze-dried for more than 24 hours. The freeze-drying temperature is set to -40~-20℃, and the vacuum degree is controlled to be less than 100Pa. The secondary sublimation temperature is set to 20~30℃, and the vacuum degree is controlled to be less than 10Pa. The water content of the sample will drop below 10%.

[0020] (6) Post-processing The freeze-dried sample is placed in a vacuum drying oven and vacuum dried at a temperature of 105~150℃. The vacuum drying time is preferably 6~24h, and the vacuum degree is set at 1~5Pa to further improve the stability and cross-linking degree of the material. Too low a temperature is not conducive to the removal of moisture, which triggers thermal cross-linking of the internal molecules of gelatin. Too high a temperature can easily lead to oxidation and degradation of gelatin. After packaging, the product can be irradiated and sterilized using Co60 gamma rays with a dose of 25~40 kGy to prepare sterile medical devices.

[0021] The finished product was tested for water absorption to evaluate its hemostatic properties. This double-layer gelatin matrix hemostatic material has excellent shape stability, with its shape remaining essentially unchanged after absorbing liquid, and its thickness changing by less than 60%.

[0022] This hemostatic material is specially designed for medical surgery, trauma treatment or military first aid. Generally, the preferred material thickness is 0.5~3mm to meet different hemostatic needs.

[0023] When the upper foam of the double-layer gelatin matrix hemostatic material contacts the wet tissue surface, the moisture on its surface is rapidly absorbed, similar to the effect of double-sided tape (DST). This rapid moisture absorption helps to form a close contact between the material and the tissue surface, thereby achieving rapid adhesion. The foaming structure of the upper foam in the double-layer gelatin structure contains cross-linked gelatin particles, which provide a certain mechanical stability, so that after absorbing water and contacting the tissue surface, the material can maintain its shape and position, and will not be easily displaced due to blood flow or pressure changes. After the cross-linked gelatin particles in the double-layer gelatin sponge come into contact with the bleeding wound, the close contact and rapid adhesion help activate platelets, prompting them to aggregate on the damaged blood vessel surface and quickly coagulate. At the same time, gelatin itself has the property of promoting blood coagulation, which can further accelerate the hemostasis process.

[0024] This foam structure containing gelatin particles is also more adaptable to different tissue surfaces. The foam structure is soft, porous and deformable, which enables it to adapt to different tissue surfaces, including irregular or wet surfaces, but it contains cross-linked gelatin particles, which helps to achieve effective hemostasis in various surgical environments. As the gelatin material degrades, its degradation products can provide necessary nutrients and signal molecules for wound healing, promoting tissue repair and regeneration.

[0025] The structure of the double-layer gelatin matrix hemostatic material achieves rapid water absorption, temporary cross-linking with blood components and tight tissue adhesion, thus providing effective hemostasis and adhesion advantages. This design not only improves hemostasis efficiency, but also helps promote wound healing and reduce postoperative complications.

[0026] The beneficial effects of adopting the above technical solution of the present invention are: (1) Rapid hemostasis: The double-layer structure design enables the material to respond quickly to bleeding points and effectively stop blood loss. The rapid degradation of the low-crosslinked layer enables the material to be quickly absorbed by the organism, reducing long-term foreign body reactions while providing initial hemostasis. The slow degradation of the high-crosslinked layer ensures that the material provides continuous support and protection during the wound healing process.

[0027] (2) Good biocompatibility: The material has good biocompatibility, reduces the risk of postoperative infection, and accelerates wound healing. The double-layer structure design allows the material to provide good biocompatibility in the early stage and reduce inflammatory response. At the same time, by controlling the degradation rate in the later stage, it avoids excessive degradation that leads to insufficient wound support.

[0028] (3) Degradable and completely absorbed: Gelatin material can be naturally absorbed by the body and has high biocompatibility, thus avoiding the risk of secondary surgery.

[0029] (4) Easy to operate: It is particularly suitable for battlefield first aid and rapid hemostasis. It is easy to operate and stops bleeding quickly. Gelatin materials can be completely absorbed by the human body and are safe and reliable. This all-gelatin design allows surgeons to stop bleeding quickly during surgery without having to worry about the problems that may be caused by the material remaining in the patient's body for a long time. During battlefield first aid, the double-layer structure gelatin matrix material can be directly circled and inserted into the bleeding point of the bullet hole. The supporting performance of the high cross-linking matrix in the double-layer structure can effectively improve the hemostasis effect.

[0030] (5) Promote wound healing: After freeze-drying, low-concentration gelatin solution forms a porous structure, which further improves the hemostatic effect and provides an environment that promotes wound healing. The double-layer structure can adapt to the different stages of wound healing, providing hemostasis and protection in the early stage, and slowly degrading in the later stage to provide space for new tissue and promote complete healing of the wound. The presence of the high cross-linking layer enhances the overall mechanical properties of the material, ensuring that the material is not easy to break or deform during the hemostasis process, providing better operability and reliability. As the low cross-linking layer degrades, signal molecules that promote tissue regeneration can be released, promoting wound healing and tissue repair.

[0031] The design of this double-layer gelatin-matrix hemostatic material, by combining two layers with different degrees of cross-linking, provides an innovative solution that can both quickly stop bleeding and adapt to the wound healing process.

[0032] The design of a double-layer gelatin matrix hemostatic material can also bring significant advantages to cartilage repair and bone repair, especially in the field of tissue engineering and regenerative medicine. The double-layer structure can provide different microenvironments to promote the growth and differentiation of chondrocytes or osteocytes. The highly cross-linked layer can provide long-lasting support, while the low cross-linked layer can promote cell migration and proliferation. The two layers with different cross-linking degrees can be designed to degrade at different rates to match the natural healing process of cartilage or bone. This helps ensure that the repair material provides the necessary support throughout the healing process. The double-layer structure can be used as a drug sustained-release carrier. Before use, doctors can infiltrate the drug solution and load the drug for sustained release, allowing the continuous release of growth factors or other bioactive molecules during the cartilage or bone repair process to promote tissue regeneration. The double-layer structure can adapt to the needs of different stages in the cartilage and bone repair process, such as initial hemostasis and inflammation control, and later cell proliferation and matrix synthesis. As the low cross-linked layer degrades, the newly formed cartilage or bone tissue can better integrate with the surrounding healthy tissue, helping to restore the function of the joint or bone. By adjusting the composition and degree of cross-linking of the double-layer structure, customized treatment plans can be provided for different patients and injury types.

[0033] In summary, the design of this double-layer gelatin matrix hemostatic material not only performs well in hemostatic applications but also shows great potential in cartilage / bone repair, providing an effective solution to promote tissue repair and regeneration. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Example 1: Preparation of a double-layer gelatin matrix hemostatic material

[0035] 1. Prepare gelatin solution: Weigh 5.0 g of gelatin, measure deionized water, pour into a beaker, and stir to dissolve in a 55°C water bath to obtain a 5% gelatin solution.

[0036] Weigh another 1.0 g of gelatin and measure deionized water, pour into another beaker, and stir and dissolve in a 55°C water bath to obtain a 1% gelatin solution.

[0037] 2. Prepare the bottom matrix: 6.0 ml of 5% gelatin solution was drawn up by a syringe and injected into a PTFE mold with a diameter of 6 cm. The mold was treated to be hydrophilic, placed in a forced air drying oven, the temperature was set to 26°C, and dried in the shade.

[0038] 3. Preparation of cross-linked gelatin particles: Weigh 100.0g of gelatin, add 900ml of deionized water, keep warm at 55℃ and stir to dissolve, put into a freeze drying plate, after it becomes gel at 4℃, transfer to -20℃ for pre-freezing treatment, and obtain gelatin sponge after freeze drying. It is vacuum heat cross-linked at 150℃ for 24h, crushed by air flow mill, and sieved into particles in the range of 50-100 mesh to obtain cross-linked gelatin particle powder.

[0039] 4. Prepare the upper foam: Weigh 1.0g of thermally cross-linked gelatin powder and put it into a syringe (volume 3.1ml). Use another syringe to draw 5.0ml of 1% gelatin solution. Connect the two syringes and push the syringes against each other for more than 20 times until they are completely mixed. Then squeeze them into the bottom matrix mold and vibrate and knock until the foam completely covers the bottom of the culture dish.

[0040] 5. Freezing and freeze-drying: Freeze in a -20℃ refrigerator and then freeze-dry in a freeze dryer.

[0041] 6. Post-processing: The freeze-dried samples were placed in a vacuum drying oven and subjected to vacuum heat treatment at 150°C for 6 h.

[0042] 7. Water absorption test: The samples were cut into standard sizes, subjected to water absorption tests, and the weight and size changes after water absorption were recorded.

[0043] Table 1 Water absorption test results of double-layer gelatin matrix hemostatic material Water absorption time (min) Weight (g) Thickness(mm) Diameter(mm) 0 0.8188 2.0 55.4 1 1.3567 2.0 55.6 5 1.9665 2.2 55.7 10 2.6783 2.2 55.9 30 3.7484 2.4 56.1 The double-layer gelatin matrix hemostatic material can absorb more than twice the liquid in 10 minutes. After absorbing the liquid, the size does not increase significantly, the thickness increases by 20%, and the structure is stable. This dimensional stability exerts little pressure on surrounding tissues in practical applications.

[0044] Example 2: Effects of cross-linked gelatin particles of different sizes on the performance of hemostatic membranes 1. Preparation of cross-linked gelatin particles of different sizes: Weigh 20.07 g of vacuum heat-crosslinked gelatin granule powder, and sieve it through 50 mesh, 100 mesh, 150 mesh, and 300 mesh stainless steel sieves respectively to collect heat-crosslinked gelatin powders of different particle sizes, including powders in three particle size ranges of 50-100 mesh, 100-150 mesh, and 150-300 mesh.

[0045] 2. Prepare gelatin solution: Weigh 5.0 g of gelatin and add deionized water to prepare a 5% gelatin solution.

[0046] 3. Preparation of double-layer structure: 5% gelatin solution was injected into the mold and after air drying, gelatin thermal cross-linking powders of different particle sizes were mixed with 1% gelatin solution, poured into the mold, and freeze-dried after freezing.

[0047] 4. Post-processing: The freeze-dried samples were placed in a vacuum drying oven and subjected to vacuum heat treatment at 150°C for 24 h.

[0048] 5. Water absorption test: The water absorption of hemostatic materials prepared with cross-linked gelatin particles of different particle sizes was tested and the swelling was recorded.

[0049] Table 2 Effects of cross-linked gelatin particles of different sizes on the water absorption properties of hemostatic materials

[0050] Cross-linked gelatin particles with a particle size range of 50-100 mesh have the fastest water absorption rate, absorbing 1.5 times the amount of water in 1 minute and more than 5.5 times in 10 minutes. The rapid water absorption rate is beneficial to intraoperative hemostasis and can induce coagulation faster. Example 3: Effect of Foam Layer Thickness and Foaming Gelatin

[0051] As in Example 2, 100-150 mesh thermally cross-linked gelatin particle powder was selected, and the foam thickness in the casting mold was adjusted to 2mm and 3mm. In addition, thermally cross-linked gelatin particle powder without adding air for foaming was used, with a thickness of 2mm. The effects of foam layer thickness and foaming conditions were compared.

[0052] Table 3 Effects of different foam thickness and foaming on water absorption properties of hemostatic materials

[0053] Under the same thickness conditions, the swelling rate of the foamed hemostatic patch is lower than that of the unfoamed one, and the water absorption rate is higher. The main reason for this is that air is mixed into the foaming process, and there is less material at the same thickness, so the porosity is larger and the water absorption rate is higher. Under the same foaming conditions, the thicker the thickness, the greater the swelling rate and the greater the water absorption rate. In clinical applications, the preferred thickness of this type of hemostatic material is 2 mm.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-layer gelatin matrix hemostatic material, characterized in that It consists of the following two layers: the first layer is a matrix layer formed by air-drying a 5-10% high-concentration gelatin solution, with a thickness of 20-100 μm; the second layer is a foam layer formed by mixing a 0.5-1% gelatin solution with cross-linked gelatin particles; after the two layers of materials are compounded, they are freeze-dried and subjected to secondary thermal cross-linking to obtain a multi-level cross-linked structure.

2. The double-layer gelatin matrix hemostatic material according to claim 1, characterized in that The cross-linked gelatin particles are obtained by cross-linking freeze-dried gelatin sponge at high temperature under vacuum and then mechanically crushing and sieving, and the particle size ranges from 50 to 300 meshes.

3. The double-layer gelatin matrix hemostatic material according to claim 1, characterized in that The gelatin is selected from type A gelatin derived from pig skin, and has a gel strength greater than 240 bloom g.

4. A method for preparing a double-layer gelatin matrix hemostatic material, characterized in that The following steps are involved: (1) Pour 5-10% gelatin solution into a hydrophilically treated PTFE mold and dry in the shade to form the first matrix layer with a thickness of 20-100 μm; (2) Mix 0.5-1% gelatin solution with cross-linked gelatin particles and inject them into the mold to form the second foam layer; (3) freezing the mold containing the double-layer gelatin structure at -20°C or lower; (4) Place the frozen sample into a freeze dryer for freeze drying; (5) Place the freeze-dried sample in a vacuum drying oven and perform vacuum drying at a temperature of 105-150°C; (6) After packaging, radiation sterilization is performed.

5. The method according to claim 4, characterized in that In step 2, the mixing ratio of the cross-linked gelatin particles and the gelatin solution is 1:4 to 1:10, and the mixing method includes a foaming process, that is, the cross-linked gelatin particle powder is loaded into a syringe, excess air is discharged, and then a predetermined amount of gelatin solution is loaded into another syringe, and the two syringes are connected by a Luer connector, and pushed against each other to mix evenly to obtain a foamed gelatin paste; the foamed gelatin paste is squeezed into a mold, the thickness of the paste is adjusted using a gasket, and it is flattened.

6. The method according to claim 4, characterized in that In step 3, the freezing time is more than 2 hours.

7. The method according to claim 4, characterized in that In step 4, the freeze-drying treatment time is more than 24 hours, the freeze-drying temperature is set to -40~-20°C, the vacuum degree is controlled to be less than 100Pa, the secondary sublimation temperature is set to 20~30°C, and the vacuum degree is controlled to be less than 10Pa.

8. The method according to claim 4, characterized in that In step 5, the vacuum drying time is 6 to 24 hours, and the vacuum degree is set at 1 to 5 Pa.

9. The method according to claim 4, characterized in that In step 6, radiation sterilization is performed using Co60 gamma rays with a dose of 25-40 kGy.

10. A hemostatic material for medical surgery, trauma treatment or military emergency treatment, characterized in that The double-layer gelatin matrix hemostatic material according to any one of claims 1 to 8 has excellent shape stability, and its appearance remains basically unchanged after absorbing liquid, and its thickness changes by less than 60%.

11. The hemostatic material according to claim 10, characterized in that The thickness of the material is 0.5-3 mm to meet different hemostasis requirements.

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