Collagen-based absorbable oral repair membrane

Abstract

This invention belongs to the field of biomedical material preparation technology and provides an absorbable oral repair membrane based on collagen. This absorbable oral repair membrane achieves one-time molding of the loose and dense layers through graded pre-freezing, with the interface bonded by interpenetrating collagen fibers, resulting in no dissection, peeling, or adhesive residue. The process is simple, requiring no complex equipment, with widely available raw materials, controllable production costs, and promising industrialization prospects. This absorbable oral repair membrane guides osteoblast ingrowth and vascularization through the loose layer and penetrates soft tissue through the dense layer barrier. It uses riboflavin photocrosslinking instead of chemical crosslinking agents such as glutaraldehyde, leaving no cytotoxic residue and exhibiting excellent biocompatibility. The preparation process allows for flexible loading of active ingredients, expanding personalized therapeutic functions such as antibacterial and osteogenic induction. The oral membrane provided by this invention has excellent clinical application prospects.

Description

Technical Field

[0001] This invention belongs to the field of biomedical material preparation technology and relates to a collagen membrane. Background Technology

[0002] Oral repair membranes are biomaterials used to promote the regeneration of oral soft tissues and bone tissues, and are widely used in alveolar bone defect repair, post-extraction protection, and periodontal tissue regeneration. By surgically placing the oral repair membrane between the oral soft tissue and the bone defect, it can prevent rapidly growing fibroblasts and epithelial cells from invading the bone defect area, creating a preferential healing space for osteoblasts. Collagen, due to its excellent biocompatibility, biodegradability, and low immunogenicity, has been widely used in the biomedical field; and the preparation of absorbable repair membranes using collagen as a raw material has become a research hotspot in oral medicine.

[0003] Existing collagen-based oral repair membranes still face the following technical challenges: uncrosslinked collagen membranes exhibit low strength and rapid degradation; while chemical crosslinking can mitigate these issues, residual crosslinking agents may be toxic, potentially hindering tissue regeneration. An ideal guided bone regeneration membrane requires a dense layer to block fibroblasts and a loose, porous layer to guide osteoblast ingrowth. Most current bilayer membranes are composited using lamination or adhesive methods, resulting in weak bonding between the two layers and easy separation during use. Existing crosslinking methods, such as chemical crosslinking, pose risks of cytotoxicity and residue; dehydration thermal crosslinking requires temperatures exceeding 65°C, which can denature collagen; and while UV-riboflavin photocrosslinking offers higher safety, its mechanical strengthening effect on collagen membranes is limited.

[0004] Therefore, how to prepare an oral repair membrane with both good mechanical properties and an integrated double-layer structure without introducing chemical cross-linking agents or damaging the natural structure of collagen is a technical problem that needs to be solved in this field. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides an absorbable oral repair membrane made from type I collagen, which has an integrated double-layer structure with no interface defects between the dense barrier layer and the loose guiding layer, resulting in a strong bond; and no cytotoxic cross-linking reagent residue.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned absorbable oral repair membrane. This method employs a graded pre-freezing method, which achieves integrated molding of a double-layer structure by controlling the morphology and size of ice crystals. Combined with UV-riboflavin photocrosslinking, the mechanical properties are significantly improved without damaging the natural structure of collagen.

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

[0008] A method for preparing an absorbable oral repair membrane based on type I collagen includes the following steps: (1) The first type I collagen solution is pre-frozen at the first pre-freezing temperature T1, and then subjected to vacuum drying once, vacuum drying twice and vacuum drying three times to obtain a loose porous layer. (2) The second type I collagen solution is covered on the loose porous layer, pre-frozen at the second pre-freezing temperature T2, and then vacuum dried once, twice and three times to obtain a double-layer collagen membrane covered with a dense layer on the loose porous layer. (3) Immerse the double-layer collagen membrane in riboflavin solution until it is completely swollen, then crosslink it under ultraviolet light, and then remove the riboflavin from the crosslinked collagen membrane; (4) The cross-linked collagen membrane is pre-frozen at the third pre-freezing temperature T3, and then subjected to vacuum drying once, vacuum drying twice and vacuum drying three times to obtain an absorbable oral repair membrane.

[0009] The concentrations of the first and second type I collagen solutions are independently selected from any concentration between 0.5% and 3%. The solvents for the first and second type I collagen solutions are water or a 0.05 M to 1.0 M acetic acid solution.

[0010] The absorbable oral repair membrane may also contain an effective dose of active ingredients, such as hydroxyapatite, β-tricalcium phosphate, nano-silver, bioactive glass, bone morphogenetic protein-2 (BMP-2), and cell growth factors, in an amount of 1% to 20% of the dry weight of type I collagen. These active ingredients may be present in the loose porous layer and / or dense layer.

[0011] The mass ratio of collagen in the first type I collagen solution to collagen in the second type I collagen solution is 1:2 to 1:5.

[0012] The first pre-freezing temperature T1 is higher than the second pre-freezing temperature T2, and the temperature difference ΔT is 20℃~50℃. In some embodiments, the first pre-freezing temperature T1 is -30℃~-25℃, the second pre-freezing temperature T2 is -60℃~-55℃, and the temperature difference ΔT is 25℃~35℃. In step (1) or (2), the pre-freezing time is independently selected from any value of 4 to 8 hours.

[0013] The third pre-freezing temperature T3 is -40℃ to -35℃, and the pre-freezing time can be any value from 4 to 8 hours.

[0014] In some embodiments, in step (1), The primary drying temperature is -10℃ to 0℃, the vacuum degree is 15 to 30 Pa, and the drying time is 12 to 24 hours. Secondary drying temperature: 0℃~10℃, vacuum degree: 10~20 Pa, drying time: 12~24 hours; The drying process involves three stages: drying temperature 20℃~30℃, vacuum degree 5~15 Pa, and drying time 6~12 hours.

[0015] In step (2), The primary drying temperature is -20℃ to -10℃, the vacuum degree is 5 to 15 Pa, and the drying time is 12 to 24 hours. Secondary drying temperature -5℃~5℃, vacuum degree 5~10 Pa, drying time 12~24 hours; The drying process involves three stages: drying temperature (10℃~20℃), vacuum degree (3~8 Pa), and drying time (6~12 hours).

[0016] In step (4), The primary drying temperature is -20℃ to -10℃, the vacuum degree is 5 to 15 Pa, and the drying time is 12 to 24 hours. Secondary drying temperature -5℃~5℃, vacuum degree 5~10 Pa, drying time 12~24 hours; The drying process involves three stages: drying temperature (10℃~20℃), vacuum degree (3~8 Pa), and drying time (6~12 hours).

[0017] The riboflavin solution has a mass percentage concentration of 0.02% to 0.3%. Crosslinking aims to improve the mechanical strength of the membrane. Relevant parameters of the crosslinking process, such as the wavelength of ultraviolet light, irradiation time, irradiation distance, irradiation intensity, and irradiation energy, can be set according to the membrane thickness, the types of active ingredients contained, and the specific application. The selection is made by testing the final mechanical strength of the product, such as tensile strength. These parameters are determined reasonably through conventional process optimization experiments. In some embodiments, the ultraviolet light irradiation intensity is 2 to 5 mW / cm². 2 Irradiation time is 15-45 minutes; total energy density is 2.7-8.1 J / cm³. 2 .

[0018] An absorbable oral repair membrane obtained by the above preparation method.

[0019] In some embodiments, the oral repair membrane has a thickness of 0.30 mm to 0.70 mm and a tensile strength of 4 MPa to 6 MPa.

[0020] A medical device or drug prepared from the above-mentioned absorbable oral repair membrane.

[0021] The mechanism / synergistic effect of this invention is as follows: This invention employs a staged pre-freezing process to achieve integrated molding of a two-layer structure: the porous layer is pre-frozen at a higher temperature T1, resulting in low ice crystal nucleation density and sufficient growth, leading to a macroporous structure after sublimation, which facilitates cell ingrowth and vascularization; the dense layer is pre-frozen at a lower temperature T2, resulting in high supercooling and high nucleation density, forming fine ice crystals, which, after sublimation, have smaller pore sizes, effectively blocking soft tissue invasion. Riboflavin is used as a photosensitive crosslinking agent in this invention, generating reactive oxygen species under UVA excitation to induce covalent crosslinking between collagen molecules, significantly improving the mechanical strength and enzymatic resistance of the membrane material; after crosslinking, the thermal stability of the membrane material is improved, enabling it to withstand secondary drying temperatures without structural collapse, ensuring sufficient dehydration and fixation.

[0022] The present invention has the following advantages: The preparation method provided by this invention achieves one-time molding of the loose and dense layers through graded pre-freezing. The interface is bonded by interpenetrating collagen fibers, resulting in no dissection, peeling, or adhesive residue. The process is simple, requires no complex equipment, uses widely available raw materials, has controllable production costs, and shows good industrialization prospects. The absorbable oral repair membrane provided by this invention guides osteoblast ingrowth and vascularization through the loose layer and penetrates soft tissue through the dense layer barrier, achieving a dual function of guiding bone regeneration and tissue regeneration. Riboflavin photocrosslinking is used instead of chemical crosslinking agents such as glutaraldehyde, resulting in no cytotoxic residues and excellent biocompatibility. The preparation process allows for flexible loading of active ingredients, such as hydroxyapatite, β-tricalcium phosphate, and bone morphogenetic protein-2. Adding 1% to 20% of the collagen dry weight has no significant impact on performance, expanding personalized therapeutic functions such as antibacterial and osteogenic induction. The oral membrane provided by this invention has good clinical application prospects. Attached Figure Description

[0023] Figure 1 Images of the porous layer (A) and dense layer (B) of the absorbable oral repair membrane prepared in Example 1; Figure 2 This is a SEM electron microscope image of the absorbable oral repair membrane prepared in Example 1. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.

[0025] Example 1: Preparation of an absorbable oral repair membrane (1) Dissolve 2.5 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 0.5% collagen solution; after standing to remove bubbles or vacuum degassing, use it as the first collagen solution; (2) Dissolve 10.0 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 2% collagen solution; allow to stand to remove bubbles or vacuum remove bubbles to obtain the second collagen solution; (3) First-stage freeze drying: The first collagen solution is injected into a circular mold with a diameter of 15 cm. The pre-freezing temperature is -30℃ and the pre-freezing time is 6 hours. The first drying temperature is -5℃ and the drying time is 12 hours with a vacuum degree of 15~30 Pa. The second drying temperature is 5℃ and the drying time is 20 hours with a vacuum degree of 10~20 Pa. The third drying temperature is 25℃ and the drying time is 8 hours with a vacuum degree of 5~15 Pa. A loose porous layer is obtained. (4) Second-stage freeze drying: The second collagen solution is injected into the surface of the loose porous layer. The pre-freezing temperature is -60℃ and the pre-freezing time is 6 hours. The first drying temperature is -15℃ and the drying time is 16 hours with a vacuum degree of 5~15 Pa. The second drying temperature is 0℃ and the drying time is 16 hours with a vacuum degree of 5~10 Pa. The third drying temperature is 15℃ and the vacuum degree is 3~8 Pa with a drying time of 10 hours to obtain a double-layer collagen membrane with a dense layer covering the loose porous layer. (5) Prepare a 0.1% riboflavin sodium phosphate solution (solvent is PBS buffer at pH 7.0); completely immerse the bilayer collagen membrane in the solution and soak at room temperature in the dark for 30 minutes; after removal, place it under 365 nm ultraviolet light with an irradiation intensity of 3 mW / cm. 2 The irradiation time was 30 minutes, resulting in a total energy of 5.4 J / cm². 2 Keep the membrane surface moist during irradiation; (6) Transfer the cross-linked collagen membrane to a cleaning container, add sufficient purified water, and wash repeatedly 5 times for 10 minutes each time until the cleaning solution shows no characteristic absorption peaks of riboflavin under UV spectrophotometer (no obvious characteristic absorption peaks at 240, 267, 372 and 444 nm, etc.); then freeze-dry again with the following drying parameters: pre-freeze at -40℃ for 6 hours, dry at -15℃ for 24 hours with a vacuum of 5~15 Pa; dry at 0℃ for 10 hours with a vacuum of 5~10 Pa; and dry at 20℃ for 8 hours with a vacuum of 3~8 Pa.

[0026] The obtained absorbable oral repair membrane appears as follows Figure 1 As shown in the images, A represents the loose, porous layer, and B represents the dense layer. The images demonstrate that the obtained absorbable oral repair membrane has a uniform texture and no obvious structural defects.

[0027] Microscopic cross-sectional image of absorbable oral repair membrane as shown below Figure 2 As shown, the upper layer is a dense layer and the lower layer is a loose porous layer. The pore size and porosity of the two are quite different, but there is no obvious sealing boundary between the two layers.

[0028] Example 2: Preparation of absorbable oral repair membrane (1) Dissolve 2.5 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4 °C for 6 hours until completely dissolved to obtain a 0.5% collagen solution; add 0.75 g of nano hydroxyapatite (nHA, particle size 20~50 nm), ultrasonically disperse at 200 W for 10 minutes, and then perform degassing treatment. After static degassing or vacuum degassing, it is used as the first collagen solution. (2) Dissolve 10.0 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 2% collagen solution; allow to stand to remove bubbles or vacuum remove bubbles to obtain the second collagen solution; (3) First-stage freeze drying: The first collagen solution is injected into a circular mold with a diameter of 15 cm. The pre-freezing temperature is -30℃ and the pre-freezing time is 6 hours. The first drying temperature is -5℃ and the drying time is 12 hours with a vacuum degree of 15~30 Pa. The second drying temperature is 5℃ and the drying time is 20 hours with a vacuum degree of 10~20 Pa. The third drying temperature is 25℃ and the drying time is 8 hours with a vacuum degree of 5~15 Pa. A loose porous layer is obtained. (4) Second-stage freeze drying: The second collagen solution is injected into the surface of the loose porous layer. The pre-freezing temperature is -60℃ and the pre-freezing time is 6 hours. The first drying temperature is -15℃ and the drying time is 16 hours with a vacuum degree of 5~15 Pa. The second drying temperature is 0℃ and the drying time is 16 hours with a vacuum degree of 5~10 Pa. The third drying temperature is 15℃ and the drying time is 10 hours with a vacuum degree of 3~8 Pa, to obtain a double-layer collagen membrane with a dense layer covering the loose porous layer. (5) Prepare a 0.1% riboflavin sodium phosphate solution (solvent is PBS buffer at pH 7.0); completely immerse the bilayer collagen membrane in the solution and soak it at room temperature in the dark for 30 minutes; after removing it, place it under 365 nm ultraviolet light with an irradiation intensity of 3 mW / cm. 2 The irradiation time was 30 minutes, resulting in a total energy of 5.4 J / cm². 2 Keep the membrane surface moist during irradiation; (6) Transfer the cross-linked collagen membrane to a cleaning container, add sufficient purified water, and wash repeatedly 5 times for 10 minutes each time until the cleaning solution shows no characteristic absorption peak of riboflavin under UV spectrophotometer; then freeze-dry again with the following drying parameters: pre-freeze at -40℃ for 6 hours, dry at -15℃ for 24 hours with a vacuum of 5~15 Pa; dry at 0℃ for 10 hours with a vacuum of 5~10 Pa; and dry at 20℃ for 8 hours with a vacuum of 3~8 Pa.

[0029] Example 3: Preparation of absorbable oral repair membrane Difference from Example 1: 0.01% nano silver (w / v) was added to the riboflavin solution in step (5) and ultrasonically dispersed evenly. The rest was the same as in Example 1.

[0030] (1) Dissolve 2.5 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 0.5% collagen solution. After standing to remove bubbles or vacuum degassing, use it as the first collagen solution. (2) Dissolve 10.0 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 2% collagen solution; allow to stand to remove bubbles or vacuum remove bubbles to obtain the second collagen solution; (3) First-stage freeze drying: The first collagen solution is injected into a circular mold with a diameter of 15 cm. The pre-freezing temperature is -30℃ and the pre-freezing time is 6 hours. The first drying temperature is -5℃ and the drying time is 12 hours with a vacuum degree of 15~30 Pa. The second drying temperature is 5℃ and the drying time is 20 hours with a vacuum degree of 10~20 Pa. The third drying temperature is 25℃ and the drying time is 8 hours with a vacuum degree of 5~15 Pa. A loose porous layer is obtained. (4) Second-stage freeze drying: The second collagen solution is injected into the surface of the loose porous layer. The pre-freezing temperature is -60℃ and the pre-freezing time is 6 hours. The first drying temperature is -15℃ and the drying time is 16 hours with a vacuum degree of 5~15 Pa. The second drying temperature is 0℃ and the drying time is 16 hours with a vacuum degree of 5~10 Pa. The third drying temperature is 15℃ and the drying time is 10 hours with a vacuum degree of 3~8 Pa, to obtain a double-layer collagen membrane with a dense layer covering the loose porous layer. (5) Add the nano-silver to a 0.1% riboflavin sodium phosphate solution (solvent is PBS buffer at pH 7.0) to a final concentration of 0.01% (g / L), disperse evenly by ultrasonication, then completely immerse the double-layer collagen membrane in the solution and soak at room temperature in the dark for 30 minutes; after removal, place it under 365 nm ultraviolet light with an irradiation intensity of 3 mW / cm 2 The irradiation time was 30 minutes, resulting in a total energy of 5.4 J / cm². 2 Keep the membrane surface moist during irradiation; (6) Transfer the cross-linked collagen membrane to a cleaning container, add sufficient purified water, and wash repeatedly 5 times for 10 minutes each time until the cleaning solution shows no characteristic absorption peak of riboflavin under UV spectrophotometer; then freeze-dry again with the following drying parameters: pre-freeze at -40℃ for 6 hours, dry at -15℃ for 24 hours with a vacuum of 5~15 Pa; dry at 0℃ for 10 hours with a vacuum of 5~10 Pa; and dry at 20℃ for 8 hours with a vacuum of 3~8 Pa.

[0031] Comparative Example 1: Preparation of an absorbable oral repair membrane (1) Dissolve 10.0 g of bovine type I lyophilized collagen in 500 mL of 0.5 M acetic acid solution and stir at 4°C for 6 hours until completely dissolved to obtain a 2.0% collagen solution. The collagen solution is then degassed. (2) Inject the degassed collagen solution into the mold, pre-freeze at -30℃ for 6 hours; first drying at -5℃ for 12 hours, vacuum at 15~30 Pa; second drying at 5℃ for 20 hours, vacuum at 10~20 Pa; third drying at 25℃ for 8 hours, vacuum at 5~15 Pa. (3) Prepare a 0.1% riboflavin sodium phosphate solution (solvent is PBS buffer at pH 7.0); completely immerse the collagen membrane in the solution and soak it at room temperature in the dark for 30 minutes; after removing it, place it under 365nm ultraviolet light with an irradiation intensity of 3 mW / cm. 2 Irradiation time: 30 minutes (total energy: 5.4 J / cm²); keep the membrane surface moist during irradiation.

[0032] (4) Transfer the cross-linked collagen membrane to a cleaning container, add sufficient purified water, and wash repeatedly 5 times for 10 minutes each time until the cleaning solution shows no characteristic absorption peak of riboflavin under UV spectrophotometer; then freeze-dry again with the following drying parameters: pre-freeze at -40℃ for 6 hours, dry at -15℃ for 24 hours with a vacuum of 5~15 Pa; dry at 0℃ for 10 hours with a vacuum of 5~10 Pa; and dry at 20℃ for 8 hours with a vacuum of 3~8 Pa.

[0033] Example 4: Physicochemical Properties of Absorbable Oral Repair Membrane 1. Thickness test Thickness tests were conducted on the absorbable oral repair membranes prepared in Examples 1-3 and Comparative Example 1. A vernier caliper with a graduation of 0.02 mm was used for measurement. Five measurement points (four corners and the center) were evenly selected on the absorbable oral repair membrane sample. The sample was placed flat between the measuring jaws, and the vernier caliper was pushed until the two measuring surfaces were just in contact with the membrane surface, avoiding excessive pressure that could deform the membrane. The thickness value at each point was read, with results accurate to 0.01 mm.

[0034] Table 1 2. Water Absorption Test The absorbable oral repair membranes prepared in Examples 1-3 and Comparative Example 1 were subjected to water absorption tests.

[0035] Accurately weigh (to the nearest 0.001 g) a sample of approximately 0.1 g, and record it as m1. Immerse the sample in a beaker containing purified water at 37°C±2℃ until it is completely soaked and saturated with water. Use tweezers to hold one corner of the sample and remove it from the water. Hold the tweezers and suspend the sample on the water surface for 1 min to drain excess water. Weigh it again and record it as m2. Calculate the water absorption ratio according to formula (1).

[0036] A = (m2 - m1) / m1 In the formula: A -- Sample water absorption ratio; m2 -- Mass of the sample after immersion in water, in grams (g). m1 -- The mass of the sample before immersion in water, in grams (g).

[0037] Table 2 The results showed that the absorbable oral repair membranes prepared in Examples 1-3 had a water absorption capacity of 30-40 times their own weight, compared to 20-30 times in the comparative example. Although both met the basic requirement of more than 20 times, the absorbency of the examples was superior to that of the comparative example, enabling them to more effectively absorb tissue fluid, stabilize blood clots, and create a more ideal healing microenvironment.

[0038] 3. Tensile strength test Tensile strength tests were conducted on the absorbable oral repair membranes prepared in Examples 1-3 and Comparative Example 1. The oral repair membranes were cut into strips 10 mm wide and 150 mm long. With a gauge length of 50 mm, the samples were placed in the universal testing machine fixture, ensuring the long axis of the sample coincided with the axis of the testing machine, and clamped securely to prevent slippage. The samples were stretched uniformly at a rate of 50 mm / min until fracture, and the maximum load (F) during the test was recorded. max ).

[0039] Table 3 The results showed that the tensile strengths of the absorbable oral repair membranes prepared in Examples 1-3 were 4.82 MPa, 5.16 MPa, and 5.03 MPa, respectively, while the tensile strength of Comparative Example 1 was 2.45 MPa. The tensile strength of the examples was superior to that of the comparative example, indicating that the present invention, through graded pre-freezing combined with UV-riboflavin photocrosslinking, improves the mechanical properties of the oral repair membrane, better meeting the requirements for barrier membrane space maintenance during oral repair surgery.

[0040] 4. Tear strength test Cut the sample into a 10 mm × 2 mm strip. Thread a 4-0 gauge suture through the sample 3 mm from the short edge. Fold the suture in half and tie a knot approximately 5 cm from the perforation to prevent it from coming loose. After saturating the sample with purified water, fix the unthreaded end and the sutured end of the sample separately on a mechanical testing machine. Tensile test at 100 mm / min until the sample tears. The maximum tensile load is taken as the tear force of this product.

[0041] Table 4 The results showed that the tear forces of the absorbable oral repair membranes prepared in Examples 1-3 were 0.48 N, 0.51 N and 0.42 N, respectively, while the tear force of Comparative Example 1 was 0.21 N. This indicates that the oral repair membrane prepared by the present invention has a certain tear resistance and can maintain structural integrity well during clinical suturing operations and when resisting soft tissue compression after implantation.

[0042] Example 5: Preparation of an absorbable oral repair membrane The difference between this embodiment and Embodiment 1 is that the temperature difference ΔT between the first pre-freezing temperature T1 (-30℃) and the second pre-freezing temperature T2 (-55℃) is 25℃. An absorbable oral repair membrane was prepared according to the method of Embodiment 1, and its physicochemical properties were tested according to the method of Embodiment 4.

[0043] The absorbable oral repair membrane prepared in this embodiment was measured to have a thickness of 0.64 mm, a water absorption ratio of 32.18, a tensile strength of 4.07 MPa, and a tear strength of 0.32 N. The results indicate that even with a relatively low temperature difference ΔT between the first pre-freezing temperature T1 and the second pre-freezing temperature T2, the prepared membrane still meets the basic mechanical performance requirements for oral repair membranes.

[0044] Example 6: Physicochemical Properties of Absorbable Oral Repair Membrane The difference between this embodiment and Embodiment 1 is that the temperature difference ΔT between the first pre-freezing temperature T1 (-25℃) and the second pre-freezing temperature T2 (-60℃) is 35℃. An absorbable oral repair membrane was prepared according to the method of Embodiment 1, and its physicochemical properties were tested according to the method of Embodiment 4.

[0045] The absorbable oral repair membrane prepared in this embodiment was measured to have a thickness of 0.54 mm, a water absorption ratio of 37.34, a tensile strength of 5.28 MPa, and a tear strength of 0.55 N. The results indicate that a higher temperature difference ΔT between the first pre-freezing temperature T1 and the second pre-freezing temperature T2 improves the mechanical properties of the membrane, demonstrating the technical advantages of this invention.

[0046] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for preparing an absorbable oral repair membrane based on type I collagen, characterized in that, Includes the following steps: (1) The first type I collagen solution is pre-frozen at the first pre-freezing temperature T1, and then subjected to vacuum drying once, vacuum drying twice and vacuum drying three times to obtain a loose porous layer. (2) The second type I collagen solution is covered on the loose porous layer, pre-frozen at the second pre-freezing temperature T2, and then vacuum dried once, twice and three times to obtain a double-layer collagen membrane covered with a dense layer on the loose porous layer. (3) Immerse the double-layer collagen membrane in riboflavin solution until it is completely swollen, then crosslink it under ultraviolet light, and then remove the riboflavin from the crosslinked collagen membrane; (4) The cross-linked collagen membrane is pre-frozen at the third pre-freezing temperature T3, and then subjected to vacuum drying once, vacuum drying twice and vacuum drying three times; The first pre-freezing temperature T1 is higher than the second pre-freezing temperature T2, and the temperature difference ΔT is 20℃~50℃; the first pre-freezing temperature T1 is -30℃~-25℃, the second pre-freezing temperature T2 is -60℃~-55℃; the third pre-freezing temperature T3 is -40℃~-35℃.

2. The preparation method according to claim 1, characterized in that, The temperature difference ΔT between the first pre-freezing temperature T1 and the second pre-freezing temperature T2 is 25℃~35℃; in steps (1), (2) and (4), the pre-freezing time can be independently selected from any value of 4 to 8 hours.

3. The preparation method according to claim 2, characterized in that, In step (1), the first drying temperature is -10℃~0℃, the vacuum degree is 15~30 Pa, and the drying time is 12~24 hours; the second drying temperature is 0℃~10℃, the vacuum degree is 10~20 Pa, and the drying time is 12~24 hours; the third drying temperature is 20℃~30℃, the vacuum degree is 5~15 Pa, and the drying time is 6~12 hours. In step (2), the first drying temperature is -20℃ to -10℃, the vacuum degree is 5 to 15 Pa, and the drying time is 12 to 24 hours; the second drying temperature is -5℃ to 5℃, the vacuum degree is 5 to 10 Pa, and the drying time is 12 to 24 hours; the third drying temperature is 10℃ to 20℃, the vacuum degree is 3 to 8 Pa, and the drying time is 6 to 12 hours. In step (4), the first drying temperature is -20℃ to -10℃, the vacuum degree is 5 to 15 Pa, and the drying time is 12 to 24 hours; the second drying temperature is -5℃ to 5℃, the vacuum degree is 5 to 10 Pa, and the drying time is 12 to 24 hours; the third drying temperature is 10℃ to 20℃, the vacuum degree is 3 to 8 Pa, and the drying time is 6 to 12 hours.

4. The preparation method according to claim 1, characterized in that, The concentrations of the first type I collagen solution and the second type I collagen solution are independently selected from any concentration of 0.5% to 3%; the mass percentage concentration of the riboflavin solution is 0.02% to 0.3%.

5. The preparation method according to claim 4, characterized in that, The mass ratio of collagen in the first type I collagen solution to collagen in the second type I collagen solution is 1:2 to 1:

5.

6. The preparation method according to claim 1, characterized in that, The solvent for the first type I collagen solution and the second type I collagen solution is water or a 0.05 M-1.0 M acetic acid solution.

7. The preparation method according to claim 1, characterized in that, The absorbable oral repair membrane also contains an effective dose of active ingredients; the active ingredients are present in the loose porous layer and / or dense layer; The active ingredient is preferably one or more of hydroxyapatite, β-tricalcium phosphate, nano-silver, bioactive glass, bone morphogenetic protein-2, and cell growth factor; the amount added is 1% to 20% of the dry weight of type I collagen.

8. The preparation method according to claim 1, characterized in that, The ultraviolet light irradiation intensity is 2~5 mW / cm². 2 Irradiation time is 15-45 minutes; total energy density is 2.7-8.1 J / cm³. 2 .

9. An absorbable oral repair membrane obtained by any one of the preparation methods described in claims 1-8, and a medical device or drug thereof prepared therefrom.

10. The absorbable oral repair membrane according to claim 9, characterized in that, The thickness is 0.30 mm to 0.70 mm, and the tensile strength is 4 MPa to 6 MPa.

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