CN114053485A

CN114053485A - Single cell structure for biological stent and application thereof

Info

Publication number: CN114053485A
Application number: CN202010762924.0A
Authority: CN
Inventors: 宋波; 张磊; 史玉升
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2022-02-18
Anticipated expiration: 2040-07-31
Also published as: CN114053485B

Abstract

The invention belongs to the technical field related to biomass structures, and particularly relates to a single cell structure for a biological scaffold and application thereof. The single cell structure is formed by connecting a plurality of double-cone-shaped rod pieces to form a Diamond structure, wherein each double-cone-shaped rod piece comprises two circular truncated cones, the bottoms of the two circular truncated cones are overlapped to form a shape with two small ends and a large middle part, on one hand, the shape reduces the rigidity and the strength of the structure and avoids the stress shielding effect of the biological stent, on the other hand, when nutrient solution passes through a part with a protruding middle part, a turbulent flow phenomenon is formed, the substance flowing speed is high, and the metabolism is accelerated. The invention solves the technical problem that the traditional lattice structure design can not simultaneously meet the matching of the mechanical and mass transfer performance with the natural skeleton.

Description

Single cell structure for biological stent and application thereof

Technical Field

The invention belongs to the technical field related to biomass structures, and particularly relates to a single cell structure for a biological scaffold and application thereof.

Background

With the development of bioengineering techniques, physicians have placed stringent demands and requirements on the biological scaffolds for surgical bone implants. The lattice structure is a novel multifunctional metamaterial which appears along with the rapid development of additive manufacturing technology in the field of material processing in recent years, and has the advantage characteristic of realizing material-structure-function integration.

The lattice structure has high relative density, and the relative density, elastic modulus, yield strength, mass transfer performance and the like which are suitable for human bones are designed through the position, the size and the material distribution of the rods, so that the lattice structure has perfect matching with a bone missing part to promote the osteoblast propagation and repair of the implant biological scaffold. In addition, the skeleton of human body has non-uniform mechanical property distribution, and through the characteristic of periodic/aperiodic arrangement of lattice structure, the structural gradient can be designed to meet the mechanical property requirements of relative density, elastic modulus and strength, but the component of gradient design has uneven permeability distribution, thereby greatly reducing the mass transfer performance, especially greatly reducing the mass transfer performance of the gradient layer with the maximum relative density. This is not only detrimental to bone repair, but may also produce stress shielding effects, leading to implant failure and health risks.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a single-cell structure for a biological stent and application thereof, and solves the technical problem that the traditional lattice structure design cannot simultaneously meet the matching of mechanical and mass transfer performance and natural bones through the design of a double-cone-shaped rod piece structure of the single-cell structure and the design of the configuration of an integral single-cell structure.

In order to achieve the above object, according to one aspect of the present invention, there is provided a unit cell structure for a biological scaffold, wherein the unit cell structure is formed by connecting a plurality of double-cone-shaped rod members to form a Diamond structure configuration, wherein the double-cone-shaped rod members include two circular truncated cones, and bottoms of the two circular truncated cones are overlapped to form a shape with two small ends and a large middle part, and the shape reduces the rigidity and strength of the structure to avoid the stress shielding effect of the biological scaffold, and forms a turbulent flow phenomenon when a nutrient solution passes through a protruding part in the middle, so that the substance flow speed is high, and the metabolism is accelerated.

Further preferably, the diameter of the top surface of the circular truncated cone is D, the diameter of the bottom surface of the circular truncated cone is D, and the change of the diameter of the cross section between the bottom surface and the top surface is gradually reduced in a linear or quadratic function trend.

Further preferably, the unit cell structure forms a derivative configuration of a Diamond structure by adjusting the diameter of the top surface and the diameter of the bottom surface of the circular truncated cone of the biconical rod piece.

Further preferably, the lattice structure is formed by 3D printing.

According to another aspect of the invention, a biomass scaffold formed by using the unit cell structure in a periodic or non-periodic arrangement is provided.

Further preferably, the biomass structure is preferably arranged between bone and bone tissue, thereby reducing the stiffness at the interface between bone and bone tissue.

Further preferably, the biomass structure is applied to a human femoral stem, cancellous bone and cortical bone.

Generally, compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the lattice structure comprises a plurality of unit cells which are uniformly and repeatedly or repeatedly arranged in a gradient manner, each unit cell of the lattice structure is formed by connecting a plurality of biconical rod pieces and nodes between a plurality of adjacent rod pieces, and the rigidity and the strength of the structure can be reduced, so that the stress shielding effect of a biological support is avoided, and the osteoblast reproduction at the skeleton is promoted; the protruding volume part of the middle area of the double-cone rod can form a turbulent flow phenomenon when nutrient solution passes through, so that the metabolism of osteoblasts and the recovery of a bone defect part are accelerated;

2. the structural mechanical property and the mass transfer property of the component of the biological scaffold lattice structure have good matching performance with natural bones, the component has stress consistency with peripheral bone tissues of a transplanted part, and the reliability and the safety of an implant are improved due to the mechanical and mass transfer properties of the component which are cooperatively regulated;

3. compared with a cylindrical rod piece, the diameter of the top surface of the double-cone rod piece provided by the invention is reduced and adjustable, so that the mechanical property of the double-cone rod piece can be adjusted and controlled, and the diameter of the bottom surface of the double-cone rod piece can be adjusted and controlled, so that the mass transfer property of the double-cone rod piece can be adjusted and controlled;

4. the single cell structure adopts a Diamond configuration, is used as a lattice structure mainly subjected to bending deformation, has mechanical properties close to those of human bones, and has orthogonal isotropy; in addition, the rods in the Diamond configuration are all inclined rods which are inclined to the bottom surface by an included angle of 54.5 degrees, and the lattice structure formed by the inclined rods is convenient for 3D printing and forming.

Drawings

FIG. 1 is a schematic representation of a biconical Diamond Unit cell constructed in accordance with a preferred embodiment of the invention;

FIG. 2 is a schematic diagram of the structure of a biconical Diamon cell constructed in accordance with a preferred embodiment of the present invention;

FIG. 3 is a schematic illustration of a different taper rod constructed in accordance with a preferred embodiment of the present invention;

FIG. 4 is a schematic diagram of a Diamond unit cell of varying taper constructed in accordance with a preferred embodiment of the present invention;

FIG. 5 is a biological scaffold structure composed of bipyramidal Diamond unicellular cells constructed in accordance with a preferred embodiment of the invention;

FIG. 6 is a comparison of mass transfer permeability of different biconical Diamond bioscaffold members constructed in accordance with a preferred embodiment of the present invention;

FIG. 7 is a schematic illustration of a double-tapered rod member constructed in accordance with a preferred embodiment of the present invention;

FIG. 8 is a Diamond bioscaffold component with stress shielding effect constructed in accordance with a preferred embodiment of the present invention.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

1-lattice multi-cell structure, 2-single-cell structure, 3-double-cone-shaped rod piece, 4-node and 11-traditional homogeneous structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1 to 5, the present invention provides a unit cell structure 2 including a plurality of double-cone rods 3, as shown in fig. 2, arranged in an array in three crystal directions [001], [100] and [010] (corresponding to X, Y and Z of a cartesian coordinate system); on the other hand, it is also possible to form a plurality of different topologically shaped Diamond unit cell configurations and corresponding rod unit cells by changing the diameter ratio of D to D in the rod elements 3 of the unit cell, wherein their diameter ratios are 1/2, 1/3, 1/4, 1/5, 1/6, 1/10, respectively. In the design process of the different topology rod pieces, the relative positions of the rod pieces in the original type unit cell are not changed, namely the spatial position of the node 4 is not changed. But as the convex degree of the middle of the rod piece is higher and higher, the structural complexity of the unit cell is increased, the mass transfer performance of the bracket is improved, and the permeability is higher; secondly, the node 4 serves as a stress concentration site, and the reduction in volume inevitably reduces the stress intensity, facilitating the matching with the intensity of the bone where the implant is located.

The plurality of unit cell structures 2 are arranged periodically/non-periodically to form a lattice multi-cell structure 1, namely a biological scaffold.

The double-cone diamondoid biological scaffold structure of the embodiment and the existing homogeneous rod diamondoid biological scaffold structure with the same node spatial position and different rod member diameters are respectively subjected to permeability flow performance test. Specifically, 7 groups of dot matrix structures are selected for flow performance test, the diameter ratios (D/D) of the rod pieces 3 are respectively 1, 1/2, 1/3, 1/4, 1/5, 1/6 and 1/10, and the diameter of the corresponding homogeneous rod piece 3 is 0.3mm in detail; the diameter D of the double-cone rod 3 is 0.3mm, and the diameters D are respectively 0.15mm, 0.10mm, 0.075mm, 0.06mm, 0.05mm and 0.03 mm. The flow performance simulation test was performed on the 7 dot matrix structures of the 7 groups, and the permeability values obtained after the test are shown in fig. 6, where: the abscissa is the ratio of different diameters, and the ordinate is the permeability. From the simulation test results, the permeability of the lattice structure of the embodiment is greatly improved under the same condition, and from the flowing mass transfer cloud chart, the lattice structure of the invention has better flowing speed at the pore, which means more efficient mass transfer capability, the problems of lower mass transfer capability and incapability of satisfying the rapid repair of human skeletal cells of the homogeneous rod Diamond biological scaffold structure are basically overcome, and the mass transfer capability of the biological scaffold structure can be fully exerted.

As shown in fig. 7, on the basis of the above-mentioned solution, in some preferred embodiments, the diameter of the double-cone rod member 3 is smallest at both ends and largest at a position midway between the ends.

Preferably, the diameter of the double-cone rod 3 changes from the middle position to the end parts at both sides, and the diameter of the middle position is the largest, and the diameters of the two end parts are the smallest, that is, the diameter of the middle area at any position is larger than the diameters of the two end parts and smaller than or equal to the diameter of the middle part.

The variation trend of the reduction of the straight radial end part in the middle of the rod piece can be linear, quadratic function and the like, and the variation trend is based on the requirements of mechanical property and mass transfer performance. Preferably, the trend is a linear function.

It should be noted that the double-cone rod member in the present invention has a diameter size that gradually changes in diameter in a direction perpendicular to the cross section, and the diameter of both ends between the rod members is smaller than the diameter in the region from the middle to both ends.

In the above-mentioned Diamond unit cell, a plurality of lattice unit cells 2 are arranged in a space cartesian coordinate system array, adjacent unit cells have a connection characteristic, and the connection mode between adjacent unit cells is a common node 4, and this periodic array arrangement mode is a lattice structure prior art, and will not be described herein.

The unit cell structure and the array mode thereof are applied to different biological scaffold parts, such as human femoral stems, cancellous bones, cortical bones and the like.

As shown in FIG. 8, a biological scaffold component comprising an example lattice structure, the internal area of the component is a conventional homogeneous structure 11, the biological scaffold of the example lattice structure is adopted for the interface of a 'hard' bone and a 'soft' bone tissue, and a biconical structure is designed between the bone tissue and the bone due to the lower rigidity of the biconical lattice structure, so that the scaffold rigidity at the interface is reduced, the stress shielding effect is weakened, and the safety and reliability of the biological scaffold structure are improved.

Preferably, the lattice-structured unit cell in this embodiment is selected as a Diamond structure.

In addition, the components of all the biological scaffold component parts can be manufactured by a 3D printing technology, and the main process is as follows:

designing a biological stent component model matched with the implantation position, dispersing the model into layers by using Materialise Magics software, and importing the dispersed files into a 3D printing device.

The 3D printing equipment carries out layer-by-layer printing processing, after each layer is finished, the substrate descends by one layer, and then the printing of the second layer is continuously finished, so that the printing is sequentially carried out layer by layer and overlapped layer by layer until all discrete layers of the parts are printed.

The parts are removed from the substrate and, if necessary, post-treatments such as shot blasting and grinding are used to improve the surface quality of the component and to improve the internal texture of the printed material.

In conclusion, the double-cone Diamond structure design adopted by the invention has the characteristic of continuous diameter change, and the complexity of the internal structure is increased, so that the mass transfer capacity of the biological scaffold structure is improved; in addition, because the node has a smaller diameter, the common stress shielding effect in the biological scaffold is overcome, and the interface physical properties of the bone tissue and the bone can be perfectly matched.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The unit cell structure for the biological stent is characterized in that the unit cell structure is formed by connecting a plurality of double-cone-shaped rod pieces to form a Diamond structure, wherein each double-cone-shaped rod piece comprises two round tables, the bottoms of the two round tables are overlapped to form a form with two small ends and a large middle part, the form reduces the rigidity and the strength of the structure on one hand and avoids the stress shielding effect of the biological stent on the other hand, when nutrient solution passes through a part protruding from the middle part, a turbulent flow phenomenon is formed, the material flow speed is high, and the metabolism is accelerated.

2. The unit cell structure according to claim 1, wherein said circular truncated cone has a top diameter D and a bottom diameter D, and the diameter of said circular truncated cone gradually decreases in a linear or quadratic trend in a cross section between said bottom and top surfaces.

3. The unit cell structure for a biological stent of claim 1, wherein the unit cell structure is derived from a Diamond structure by adjusting the diameter of the top surface and the diameter of the bottom surface of the truncated cone of a biconical rod.

4. The unit cell structure for a biological scaffold of claim 1, wherein the lattice structure is formed by 3D printing.

5. A biomass scaffold formed using the unit cell structure of any of claims 1-4 in a periodic or aperiodic arrangement.

6. Bioscaffold according to claim 5, wherein said biomass structure is preferably arranged between bone and bone tissue, whereby the stiffness at the interface between bone and bone tissue is reduced.

7. The bioscaffold of claim 5, wherein the biomass structure is used in human femoral stem, cancellous bone and cortical bone.