A medical degradable composite material dot array structure and a preparation method thereof

Abstract

The application discloses a kind of medical degradable composite lattice structure and preparation method thereof, the lattice structure is constituted by upper panel, lower panel and lattice core. Upper panel and lower panel are all used silk fabric reinforced degradable thermoplastic polymer matrix composite, lattice core is used unidirectional silk fiber bundle reinforced degradable thermoplastic polymer matrix composite. Lattice core is periodically arranged by multiple pyramid type unit cells, and each unit cell is the pyramid type integrated piece composed of four bars. The preparation of lattice core includes the preparation of silk grid fabric, fabric is over-slimed and dried, is punched into shape. The silk fiber used in the application has balanced elastic modulus, tensile strength and elongation at break, which can effectively improve the strength and toughness of the composite material, and the prepared lattice structure has excellent compression energy absorption characteristics. In addition, silk fiber has water absorption, cell affinity and bone tissue compatibility, which can adjust the in-vivo and in-vitro degradation rate of the composite material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of composite materials and structures, in particular to a composite material lattice structure applied to the biomedical field and a preparation method thereof. BACKGROUND

[0002] Biodegradable biomaterials and implants with ideal mechanical and biological properties are urgently needed in the biomedical field, especially in the field of tissue engineering. For young people's tissue damage such as trauma and sports injury, the tissue engineering strategy proposes to use biodegradable implants, which can not only meet the structural stability of the damaged part, but also completely degrade and realize tissue replacement within a certain period, avoiding secondary surgery, reducing patient pain and reducing medical costs. Biodegradable medical polymer materials such as polylactic acid (PLA) and polycaprolactone (PCL) have good biocompatibility and degradability, and have been widely used in biodegradable implant devices. However, these biodegradable polymer materials have obvious shortcomings in mechanical properties. For example, PLA materials have low toughness and are prone to fragmentation after implantation; PCL materials have low mechanical strength and are prone to deformation, making it difficult to meet the structural support requirements. In addition, implants need to resist impact loads during movement during use, so excellent energy absorption and impact resistance are also one of the necessary conditions.

[0003] Lattice structure is an ordered open-cell structure composed of periodic units, which has the characteristics of light weight and high strength. The pore size and pore density of the lattice structure have a wide range of changes, and the designability is strong. The internal pores are interconnected, which is beneficial to cell migration, blood penetration, and nutrient transport. Therefore, the lattice structure has broad application prospects in the field of tissue engineering. Through the design of the lattice structure, the apparent density and modulus of the traditional material can be adjusted, thereby increasing the mechanical adaptability of the implant and the surrounding tissue. The patent with the application number CN113231644A designs the apparent density and modulus of the Ti6Al4V alloy lattice material microstructure based on the Wolf law, which is mechanically compatible with human cortical bone, and relieves the stress shielding effect. The patent with the application number CN113304312A designs a Kagome-based micro-lattice skull repair material and adjusts its microstructure and mechanical properties to make it more compatible with real skull. Although the porous structure / lattice structure of medical metal materials such as titanium alloy can relieve the stress shielding in the bone tissue application scenario to a certain extent, its modulus is much higher than that of biological tissues and is not degradable, which may induce inflammation, so people expect to obtain a substitute material with lower modulus. On the other hand, although polymer-based composite lattice structures are widely used in engineering, there are related patents, but there are few reports on lattice structures based on biodegradable medical polymer materials.

[0004] In view of the above medical degradable material and implant body requirements, the application proposes to use natural silk to reinforce degradable polymer material to prepare a degradable polymer matrix composite material, and further prepare a dot matrix structure, so that the dot matrix structure of the composite material has degradability, excellent mechanical properties and energy absorption characteristics, and has application potential in medical degradable materials and implants. SUMMARY

[0005] The application provides a composite material dot matrix structure and a preparation method thereof for application in the field of biological medicine, which uses silk fibers to reinforce a degradable medical polymer matrix to improve the mechanical properties of the dot matrix structure of the composite material and make the dot matrix structure have excellent energy absorption performance.

[0006] Firstly, the application provides a medical degradable composite material dot matrix structure, which is composed of an upper panel, a lower panel and a dot matrix core, and the dot matrix core is fixed between the parallel upper and lower panels;

[0007] The upper and lower panels of the composite material dot matrix structure are both degradable polymer composite materials reinforced by silk fabrics, and the dot matrix core is a degradable thermoplastic polymer composite material reinforced by unidirectional silk fiber bundles;

[0008] The silk fabric is a plain fabric knitted by orthogonal fiber bundles;

[0009] The dot matrix core is composed of periodically arranged pyramidal unit cells, and each unit cell is a pyramidal integral part composed of four rods;

[0010] The node of the dot matrix core is a plain knitted structure formed by interweaving unidirectional silk fiber bundles, and the silk fiber bundles in two directions form an angle of 90 degrees;

[0011] The unidirectional silk fiber bundles are subjected to degumming and twisting treatment, and the twist of the fibers is 500 twists to 1500 twists;

[0012] The degradable thermoplastic polymer has biocompatibility and degradability, and includes polylactic acid (PLA), polycaprolactone (PCL) and the like;

[0013] The volume ratio of the fiber bundles in the unidirectional silk fiber bundle reinforced degradable polymer composite material is 40% to 80%.

[0014] Secondly, the application provides a preparation method of a medical degradable composite material dot matrix structure, which includes the following steps:

[0015] (1) The unidirectional silk fiber bundles are knitted along two orthogonal directions to form a grid-shaped fabric, and the fibers at the nodes of the grid are densely interwoven, and the nodes are unidirectional fiber bundles;

[0016] (2) heating and melting the thermoplastic polymer, immersing the grid fabric obtained in step (1) in the polymer melt for sizing, taking out the fabric after the fabric is completely infiltrated and waiting for the melt to solidify, to obtain a flat grid structure of the fiber-reinforced polymer composite material;

[0017] (3) adjusting the sizing times according to the design requirements of the volume fraction of the silk in the composite material, and the volume fraction of the polymer will increase and the volume fraction of the silk will decrease accordingly with each additional sizing;

[0018] (4) designing a stamping die according to the node and connecting rod size of the grid fabric;

[0019] (5) locally heating the flat grid structure of the fiber-reinforced polymer composite material obtained in step (2) to soften the polymer, and stamping forming by using the stamping die to obtain a dot matrix core;

[0020] (6) alternately stacking and laying the silk fabric and the degradable polymer film, wherein the plain silk fabric is alternately laid along the 0° and 45° directions, and the upper and lower panels of the dot matrix structure are obtained by hot pressing;

[0021] (7) bonding the dot matrix core obtained in step (5) after heating with the upper and lower panels obtained in step (6) to obtain a dot matrix structure.

[0022] Finally, the application provides a medical degradable composite material dot matrix structure prepared according to the above preparation method.

[0023] Compared with the prior art, the application has the following advantages:

[0024] The application uses silk fiber to reinforce the degradable polymer-based composite material, and the three of the elastic modulus, tensile strength and elongation at break of the silk fiber are balanced, which can effectively improve the comprehensive mechanical properties of the composite material, and the energy absorption characteristics of the material are improved by combining the dot matrix structure design. In addition, the silk fiber has water absorption and biocompatibility, which can promote the in-vivo and in-vitro degradation of the composite material dot matrix structure and improve its application potential in the field of tissue engineering.

[0025] The application uses the grid weaving-stamping forming method to prepare the composite material dot matrix structure, on the one hand, the fibers are interwoven at the grid nodes to enhance the mechanical properties at the nodes, which can significantly reduce the delamination failure of the composite material in the pyramid dot matrix structure during loading; on the other hand, the weaving process of the silk fiber is mature and the stamping forming process is simple, which can realize the low-cost large-scale preparation of the dot matrix structure. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1The composite material lattice structure provided in one embodiment of the present invention includes 1-upper panel, 2-lower panel, 3-lattice core, and 4-lattice unit cell.

[0027] Figure 2 This is a schematic diagram of the design of a unidirectional silk fiber bundle mesh fabric in an embodiment of the present invention.

[0028] Figure 3 The diagram shown is a schematic diagram of the process of preparing the lattice core using a stamping die in an embodiment of the present invention.

[0029] Figure 4 The diagram shows (a) a schematic diagram of the preparation process of the upper and lower panels in an embodiment of the present invention and (b) the prepared panels.

[0030] Figure 5 The figure shown is a microscopic cross-sectional view of a lattice rod made of unidirectional silk fiber composite material in an embodiment of the present invention.

[0031] Figure 6 The images show HE staining images of rat subcutaneous implantation models of silk fiber reinforced polycaprolactone composite material and polycaprolactone material control group, with (a) showing material and tissue staining images 14 days after implantation and (b) showing material and tissue staining images 28 days after implantation. Detailed Implementation

[0032] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0034] In the present application, when a numerical interval (i.e. a numerical range) is involved, the distribution of the optional values in the numerical interval is considered to be continuous and includes both numerical endpoints (i.e. the minimum value and the maximum value) of the numerical interval and each value between the two numerical endpoints, unless otherwise specified. When a numerical interval refers only to integers in the numerical interval, unless otherwise specified, it is equivalent to directly listing each integer, including both endpoint integers and each integer between the two endpoints. When multiple numerical ranges are provided to describe a feature or a characteristic, the numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in the present application should be understood to include any and all sub-ranges encompassed therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is intended to broadly include quantitative intervals such as percentage intervals, ratio intervals, and value intervals.

[0035] In the present application, "optionally", "optional", or "option" means that it can or can not be present, i.e. it is selected from either of the two parallel options "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "option" is independent of each other.

[0036] In the present application, the terms "first", "second", etc. in "first aspect", "second aspect", etc. are only for descriptive purposes and should not be understood as indicating or implying relative importance or quantity, nor should it be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and should be understood as not constituting a closed limitation on the quantity.

[0037] In the following examples and comparative examples, the raw materials not specifically mentioned are commercially available products; the operation steps and operation parameters not specifically mentioned are reasonably selected by the person skilled in the art based on experience.

[0038] The first aspect of the present application provides a composite material lattice structure.

[0039] In some embodiments, as shown in Figure 1 The composite material lattice structure comprises an upper panel 1, a lower panel 2, and a lattice core 3 fixed between the parallel upper panel and lower panel;

[0040] In some embodiments, the upper panel and the lower panel of the composite material lattice structure are both made of silk fabric reinforced degradable polymer composite material, and the lattice core is made of unidirectional silk fiber bundle reinforced degradable polymer composite material.

[0041] In some embodiments, the lattice core is made of a silk fabric reinforced degradable polymer composite material as shown in Figure 1The plurality of periodic pyramid lattice structure cells 4 shown are each composed of four rods forming a pyramid-shaped integral piece;

[0042] In some embodiments, the unidirectional silk fiber bundles at the lattice core node are interlaced and distributed in a plain weave structure;

[0043] In some embodiments, the silk fabric is a quadrature plain weave structure;

[0044] In some embodiments, the unidirectional silk fiber bundles are subjected to degumming and twisting treatment, and the twist of the fiber bundles is 500-1500, for example, 500 twists, which means that the fiber bundles are twisted 500 times per meter. If the fiber twist is less than 500, the fiber bundles will be divided into strands, affecting the fiber weaving process. If the twist is higher than 1500, the fiber bundles will be too rigid, which is not conducive to weaving and impregnation of the polymer melt.

[0045] The present application uses silk fiber to reinforce degradable thermoplastic polymers to prepare composite lattice structures. The three properties of the silk fiber used, i.e. elastic modulus, strength and elongation at break, are balanced, which can effectively enhance the mechanical properties of the degradable polymer and make the prepared lattice structure have excellent energy absorption characteristics.

[0046] In some embodiments, the degradable thermoplastic polymer has biocompatibility and degradability, and optionally, the degradable thermoplastic polymer includes at least one of polylactic acid (PLA), polycaprolactone (PCL), etc.

[0047] In some embodiments, the volume fraction of the unidirectional silk fiber bundles in the degradable thermoplastic polymer composite material is 40%-80%, for example, it can be 40%, 55%, 65%, or 75%.

[0048] The present application uses silk fiber, which has water absorption and cell affinity, to improve the in vivo and in vitro degradation rate of the prepared composite lattice structure, which is beneficial to its application in the field of tissue engineering.

[0049] In a second aspect, the present application provides a preparation method of a composite lattice structure applied in the field of biomedical materials, which comprises:

[0050] The unidirectional silk fiber bundles are woven along two directions at an angle of 90° to form a grid-shaped fabric, including densely woven nodes and unidirectional fiber bundles connecting the nodes;

[0051] The unidirectional silk fiber bundles used in the present application have good flexibility, and the interlaced distribution of the fibers at the grid nodes enhances the mechanical properties of the nodes, effectively reducing the probability of delamination failure at the nodes in the pyramid lattice structure.

[0052] The thermoplastic polymer is heated and melted, the silk fiber mesh fabric is immersed in the polymer melt for sizing, the fabric is taken out after being completely impregnated and the melt is cooled and solidified to obtain a flat mesh structure of the fiber-reinforced polymer matrix composite; the sizing frequency is adjusted according to the design requirements of the volume fraction of the silk in the main load-bearing member of the dot matrix structure; the obtained flat mesh structure is locally heated to soften the polymer matrix, and is stamped by using a stamping die to obtain a dot matrix core.

[0053] In some embodiments, the polymer material comprises polycaprolactone (PCL), and the melt sizing method comprises the following steps:

[0054] a. heating PCL powder / particles above its melting point (for example, 100℃) to obtain liquid PCL;

[0055] b. immersing the mesh fabric in the liquid PCL, taking out the fabric after being completely impregnated, and cooling and solidifying the melt;

[0056] c. repeating step b.

[0057] The silk fabric and the polymer film are alternately stacked and laid, wherein the silk fiber cloth is alternately laid along the 0° and 45° directions, and hot pressing is performed to obtain upper and lower panels of the dot matrix structure.

[0058] The nodes of the dot matrix core are bonded with the upper and lower panels to obtain the dot matrix structure.

[0059] The silk fiber weaving process and the stamping process used in the present application are simple and mature, and the combination of the two can realize the low-cost and large-scale preparation of the dot matrix structure of the medical composite material.

[0060] Example 1

[0061] A preparation method of a medical degradable composite material dot matrix structure, comprising the following steps:

[0062] S1: preparing a mesh fabric

[0063] The silk fiber bundle with a specification of 19 denier and a single twist of 500 is selected for weaving, and the obtained mesh fabric is as shown in the schematic Figure 2 The fibers are interlaced at the nodes and form a plain weave structure, as shown in the local enlarged view.

[0064] S2: preparing a composite material flat mesh structure

[0065] a. weighing a certain amount of PCL with a molecular weight of 80000, heating to 120℃ and keeping warm until completely melted;

[0066] b. The grid fabric obtained in step S1 is dipped into a PCL melt for sizing, and after the fabric is completely impregnated, it is taken out and the PCL is allowed to cool and solidify at room temperature;

[0067] c. Step b is repeated twice for sizing, and the volume fraction of the fiber bundle in the obtained lattice core is 70%.

[0068] S3: Preparation of a lattice structure

[0069] a. As shown in Figure 3 , the stamping die and punch are heated to 60℃ and kept at this temperature, the nodes of the grid structure of the flat plate-shaped composite material obtained in S2 are placed directly below the punch of the stamping die, the length direction of the punch forms a 45° angle with the direction of the fiber bundle in the grid, after stamping, the grid structure is moved to the next node, and this process is repeated until all the rods are stamped, and a lattice core is obtained;

[0070] b. As shown in Figure 4 , the silk plain fabric and polymer film are alternately stacked and laid, and the silk fabric is alternately laid in the 0° and 45° directions, and then hot-pressed at 120℃ and 0.28MPa for 30 minutes, and after cooling, a composite material is obtained;

[0071] c. The upper and lower panels are cut according to the design size of the lattice sandwich structure, and the nodes of the lattice core are locally heated and then hot-melt bonded with the upper and lower panels to obtain a lattice structure.

[0072] The cross-sectional micro-morphology of the unidirectional composite material rod in the lattice core is shown in Figure 5 .

[0073] The in vivo biocompatibility of the silk fiber reinforced polycaprolactone composite material was verified by a rat subcutaneous implantation model, and the results are shown in Figure 6 . After 14 days of implantation, a thin layer of fibrous capsule was formed on the outer layer of the silk fiber reinforced polycaprolactone composite material, indicating that a foreign body inflammatory reaction occurred, but after 28 days of implantation, cells and blood vessels began to enter the material, indicating that the material had good biocompatibility and could degrade and induce tissue regeneration.

[0074] Example 2

[0075] The unidirectional silk fiber bundle described in the application is twisted, and the twist of the fiber is 500-1500, for example, it can be 500 twists, 800 twists, 1000 twists, 1200 twists, or 1500 twists.

[0076] The lattice structure of the composite material is prepared according to the method of Example 1, except that the twist of the unidirectional silk fiber bundle is 1500 twists, and the volume fraction of the silk fiber in the rod of the grid structure of the composite material is 65%.

[0077] A preparation method of a medical degradable composite material lattice structure, comprising the following steps:

[0078] S1: preparing a grid-shaped fabric

[0079] The obtained fabric is knitted by selecting a silk fiber bundle with a specification of 19 denier and a single twist of 1500, and the fibers at the nodes of the fabric are densely interwoven and distributed to form a plain weave grid structure.

[0080] S2: preparing a composite material plate-shaped grid structure

[0081] a. A PCL with a molecular weight of 80000 is weighed, heated to 120 DEG C and kept at 120 DEG C until completely melted;

[0082] b. The grid-shaped fabric obtained in step S1 is immersed in the PCL melt for sizing, and after the fabric is completely immersed, it is taken out and the PCL is cooled and solidified at room temperature;

[0083] c. Repeat step b, size 2 times, and the volume fraction of silk fibers in the obtained lattice core is 65%.

[0084] S3: preparing a lattice structure

[0085] a. As shown in Figure 3 , the stamping die and punch are heated to 60 DEG C and kept at 60 DEG C, the nodes of the plate-shaped composite material grid structure obtained in S2 are placed directly below the punch of the stamping die, the length direction of the punch forms a 45 DEG angle with the fiber bundle direction in the grid, and after stamping, the grid structure is moved to the next node, and the process is repeated until all the rods are stamped, and the lattice core is obtained;

[0086] b. As shown in Figure 4 , the silk plain fabric and the polymer film are alternately stacked and laid, wherein the silk fabric is alternately laid along 0 DEG and 45 DEG directions, and hot pressing is carried out at 120 DEG C and 0.28 MPa for 30 minutes, and the composite material is obtained after cooling;

[0087] c. The upper and lower panels are cut according to the design size of the lattice sandwich structure, and the nodes of the lattice core are locally heated and hot-melt bonded with the upper and lower panels to obtain the lattice structure.

[0088] Example 3

[0089] The grid-shaped fabric is sized in the polymer melt, and the sizing times can determine the proportion of the polymer matrix in the composite material, and also conveniently adjust the volume fraction of the silk fibers in the composite material.

[0090] The composite material lattice structure is prepared according to the method of Example 1, and the difference is that the silk grid-shaped fabric is sized in the polymer melt for 5 times, and the volume fraction of the silk fibers in the composite material is reduced to 45%.

[0091] A method for preparing a medical degradable composite lattice structure, comprising the following steps:

[0092] S1: preparing a grid-shaped fabric

[0093] A silk fiber bundle with a specification of 19 denier and a single twist of 500 is selected for weaving. The fibers at the nodes of the obtained fabric are densely interwoven and distributed to form a plain weave grid structure.

[0094] S2: preparing a composite flat lattice structure

[0095] a. A certain amount of PCL with a molecular weight of 80000 is weighed, heated to 120°C and kept at this temperature until completely melted;

[0096] b. The grid-shaped fabric obtained in step S1 is immersed in the PCL melt for sizing. After the fabric is completely infiltrated, it is taken out and the PCL is cooled and solidified at room temperature;

[0097] c. Repeat step b for 5 times. The volume fraction of silk fibers in the obtained lattice core is 45%.

[0098] S3: preparing a lattice structure

[0099] a. As shown in Figure 3 , the stamping die and punch are heated to 60°C and kept at this temperature. The nodes of the flat lattice structure obtained in S2 are placed directly below the punch of the stamping die. The length direction of the punch forms a 45° angle with the direction of the fiber bundle in the lattice. After stamping, the lattice structure is moved to the next node. This process is repeated until all the rods are stamped. The lattice core is obtained;

[0100] b. As shown in Figure 4 , the silk plain fabric and polymer film are alternately stacked and laid. The silk fabric is alternately laid along 0° and 45° directions. Hot pressing is carried out at 120°C and 0.28MPa for 30 minutes. After cooling, the composite material is obtained;

[0101] c. The upper and lower panels are cut according to the design size of the lattice sandwich structure. The nodes of the lattice core are partially heated and then hot melt bonded with the upper and lower panels to obtain the lattice structure.

[0102] Example 4

[0103] In some embodiments, the degradable thermoplastic polymer has biocompatibility and degradability. Optionally, the degradable thermoplastic polymer includes at least one of polylactic acid (PLA), polycaprolactone (PCL), etc.

[0104] Prepare the composite lattice structure according to the method of Example 1, except that the type of degradable thermoplastic polymer is adjusted, and the degradable thermoplastic polymer used is polylactic acid (PLA), the melting temperature is 230℃, and the heating temperature of the punch die and punch is 100℃.

[0105] A method for preparing a medical degradable composite lattice structure, comprising the following steps:

[0106] S1: Prepare a mesh fabric

[0107] Select a silk fiber bundle with a specification of 19 denier and a single twist of 500 for weaving, and the resulting fabric has dense interwoven fibers at the nodes and forms a plain weave grid structure.

[0108] S2: Prepare a composite flat lattice structure

[0109] a. Weigh a certain amount of PLA with a molecular weight of 50000, heat to 230℃ and keep warm until completely melted;

[0110] b. Dip the mesh fabric obtained in step S1 into the PLA melt for sizing, and take it out after the fabric is completely infiltrated and cool the PLA at room temperature to solidify;

[0111] c. Repeat step b for 2 times, and the volume fraction of silk fiber in the lattice core obtained is 58%.

[0112] S3: Prepare a lattice structure

[0113] a. As shown in Figure 3 , heat the punch die and punch to 100℃ and keep warm, place the nodes of the flat composite lattice structure obtained in S2 directly below the punch of the punch die, and the length direction of the punch forms a 45° angle with the direction of the fiber bundle in the lattice. After forming, move the lattice structure to the next node and repeat the process until all the rods are punched, obtaining a lattice core;

[0114] b. As shown in Figure 4 , stack and lay the silk plain fabric and polymer film alternately, where the silk fabric is laid alternately along 0° and 45° directions, and hot-press at 230℃, 0.28MPa for 30 minutes, and obtain the composite material after cooling;

[0115] c. Cut the upper and lower panels according to the design size of the lattice sandwich structure, and heat the nodes of the lattice core locally and then hot-melt bond with the upper and lower panels to obtain the lattice structure.

[0116] Comparative Example 1

[0117] The composite lattice structure was prepared according to the method of Example 1, except that the twist of the unidirectional silk fiber bundle was 1500 twists, high twist was not conducive to sizing, and the silk fiber volume fraction was increased to 80% after sizing once.

[0118] Comparative Example 2

[0119] The composite lattice structure was prepared according to the method of Example 1, except that the twist of the unidirectional silk fiber bundle was 1500 twists, high twist was not conducive to sizing, and the silk fiber volume fraction was increased to 80% after sizing once.

[0120] Test Example 1

[0121] In order to reflect the mechanical and biodegradation performance advantages of the composite material prepared according to the present application, the performance of each example and comparative example was compared, and the test method was as follows:

[0122] The compression mechanical test of the composite lattice structure was carried out on the SANS screw-driven testing machine according to the method of ASTM C365 / C 364M-05, and the compression displacement rate was set to 0.01 mm / s. The lattice structure contained 3x3 unit cells and upper and lower panels, and the size of the unit cell was 10 mm x 10 mm x 5 mm (length x width x

[0123] height), and the size of the upper and lower panels was 30 mm x 30 mm x 1 mm (length x width x height). Three samples of each composite lattice structure were repeated, the compression force-displacement curve was recorded, the compression energy absorption was calculated by area integration of the curve, and the results were averaged for three times.

[0124] The in vitro degradation performance of the composite lattice structure was tested by using the unit cell, and the size was 10 mm x 10 mm x 5 mm (length x width x height). After weighing, it was immersed in a 37℃ degradation solution, the degradation solution was replaced every week, and after 6 months, it was taken out, dried and weighed, the weight loss percentage was recorded, and each sample was repeated for three times. The degradation solution was PBS phosphate buffer solution with pH = 7.4, and 1 U / mL XIV protease and 1 U / mL lipase were added.

[0125] The specific results are shown in Table 1. The results show that when the volume fraction of silk is 80% or more, the compression energy absorption of the lattice structure of the composite material is lower than that of the lattice structure of 70%, because the content of resin in the composite material is too low, and the bonding and stress transfer effect between the fibers are poor. When the volume fraction of silk is 30% (lower than 40%), the compression energy absorption of the lattice structure of the composite material is low, and the low content of silk leads to poor compression resistance. In the degradation experiment, the silk degrades more slowly than the matrix resin due to its highly ordered molecular structure. The weight loss of Comparative Example 1 is 25.2% in 6 months, which is too slow and is not conducive to bone repair. The weight loss of Comparative Example 2 is too much, and the degradation is too fast to maintain the mechanical microenvironment required for bone repair. Therefore, the prepared composite material lattice structure meets the mechanical properties and degradation rate required for bone repair.

[0126] Silk volume fraction Composite lattice structure compression energy absorption In vitro degradation 6 months weight loss percentage Example 1 70％ 8.5 x 10 5 J]] 35.6％ Example 2 65％ 7.2 x 10 5 J]] 42.3％ Example 3 45％ 5.1 x 10 5 J]] 57.2％ Example 4 58％ 5.8 x 10 5 J]] 48.9％ Comparative Example 1 80％ 4.2 x 10 5 J]] 25.2％ Comparative Example 2 30％ 2.1 x 10 5 J]] > 80% (material shatters)

[0127] The above description of the present application is illustrative rather than limiting and many modifications, changes, and equivalents will become apparent to those skilled in the art based on the above description, which is intended to be within the spirit and scope of the claims.

Claims

1. A biodegradable composite lattice structure for medical use, the lattice structure comprising an upper panel, a lower panel, and a lattice core, wherein the lattice core is fixedly disposed between the parallel upper and lower panels; wherein: Both the upper and lower panels are made of biodegradable thermoplastic polymer composite material reinforced with silk fiber cloth, and the lattice core is made of biodegradable thermoplastic polymer composite material reinforced with unidirectional silk fiber bundles. The volume ratio of the fiber bundles in the biodegradable thermoplastic polymer composite material reinforced with unidirectional silk fiber bundles is 40% to 75%. The lattice core is composed of multiple periodic pyramid-shaped lattice structure units, and each unit is a pyramid-shaped integral piece composed of four rods. The unidirectional silk fiber bundles at the core nodes of the lattice are alternately distributed to form a plain weave structure.

2. The medical biodegradable composite lattice structure according to claim 1, wherein: The silk fiber cloth is plain woven, including two silk fiber directions at a 90° angle; The unidirectional silk fiber bundles are degummed and twisted, with a fiber twist of 500~1500 turns / meter.

3. The medical biodegradable composite lattice structure according to claim 1, wherein: The biodegradable thermoplastic polymer is selected from polylactic acid, polycaprolactone, and other biodegradable polyester polymers.

4. A method for preparing a medical biodegradable composite lattice structure according to any one of claims 1 to 3, comprising: (1) The unidirectional silk fiber bundles are woven to form a mesh fabric. The fabric includes two silk fiber directions at a 90° angle, and the fibers at the mesh nodes interweave to form a plain weave structure. (2) Melt the thermoplastic polymer, slurry the mesh fabric in the polymer melt, take it out after the fabric is completely wetted, and wait for the melt to cool and solidify to obtain a flat mesh fabric with polymer coating on the surface. (3) Adjust the number of sizing cycles according to the design requirements for the volume fraction of unidirectional silk fibers; (4) Design the stamping die according to the size of the nodes and connecting rods of the mesh fabric; (5) The flat mesh fabric obtained in step (3) is stamped and formed step by step using a stamping die according to the shortest periodic length at a 45° angle to obtain the dot matrix core; (6) The plain silk fabric and polymer film are stacked alternately, wherein the silk fabric is laid alternately along the 0° and 45° directions, and hot-pressed to obtain the upper and lower panels with a dot matrix structure; (7) After heating the lattice core obtained in step (5), it is bonded to the upper and lower panels obtained in step (6) to obtain a medical biodegradable composite material lattice structure.

5. A medical biodegradable composite lattice structure prepared by the preparation method according to claim 4.

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