Microenvironment-adjustable 4D (four-dimensional) printed bone tissue scaffold as well as preparation method and application thereof

Abstract

The invention provides a microenvironment-adjustable 4D printed bone tissue scaffold as well as a preparation method and application thereof, and relates to the technical field of bone repair. The microenvironment-adjustable 4D printed bone tissue stent comprises a stent structure and a membrane covering the surface of the stent structure, and holes are formed in the stent structure; under the condition that the support structure is stressed and deformed under stimulation of ultrasonic waves, the holes are configured to be switched between the contact state and the separation state. In the stress deformation process of the stent structure, the holes can be switched between a contact state and a separation state, a triboelectric effect is generated, and then micro-current is generated, so that a physical microenvironment beneficial to cell growth is constructed, and regeneration of damaged bone tissues is further facilitated; ultrasonic waves are used as mechanical waves, extra mechanical stimulation is provided at the bone defect position, the scaffold structure can be stressed and deformed, the scaffold structure can also generate a piezoelectric effect and a triboelectric effect, the surface of the scaffold structure is induced to generate micro-current, and therefore a physical microenvironment beneficial to cell growth is constructed, and regeneration of damaged bone tissue is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of bone repair, and in particular to a 4D printed bone tissue scaffold capable of regulating a microenvironment, and a preparation method and application thereof. Background Art

[0002] Clinically, when bone defects are larger than the critical size of 2.5 cm due to trauma, infection debridement, tumor resection, congenital dysplasia, etc., the body cannot repair itself spontaneously, often causing severe incomplete healing. At this time, bone transplantation is the most commonly used treatment method in clinical practice, and autologous tissue transplantation or allogeneic tissue transplantation is often used. However, autologous tissue transplantation is often accompanied by new trauma or is limited by the conditions of the donor site, making it difficult to achieve a therapeutic effect. Allogeneic tissue transplantation has problems with donor sources and immune rejection. Especially for larger bone defects, traditional treatment methods can no longer meet medical needs.

[0003] The development of tissue engineering technology has provided another option for the repair and reconstruction of damaged tissues. Bioscaffolds are a key factor in tissue engineering technology research. Bioscaffolds can serve as templates to guide the regeneration of damaged tissues. However, existing bioscaffolds lack a physical microenvironment suitable for cell growth, making it difficult to achieve the function of regenerating damaged bone tissue. Summary of the invention

[0004] The problem solved by the present invention is how to solve the problem that the damaged bone tissue is difficult to regenerate due to the lack of a physical microenvironment suitable for cell growth in the existing biological scaffold.

[0005] In order to solve the above problems, the present invention provides a 4D printed bone tissue scaffold capable of adjusting the microenvironment, and a preparation method and application thereof.

[0006] In a first aspect, the present invention provides a 4D printed bone tissue scaffold capable of regulating a microenvironment, comprising a scaffold structure and a membrane covering the surface of the scaffold structure, wherein the scaffold structure is provided with holes;

[0007] The holes have a contact state in which the opposite edges are in contact with each other and a separation state in which the opposite edges are not in contact with each other. When the support structure is deformed by force under the stimulation of ultrasound, the holes are configured to switch between the contact state and the separation state.

[0008] Optionally, a surface of the membrane away from the support structure is provided with micro-pillars, the micro-pillars have a collapsed state and an upright state, and the micro-pillars are configured to switch between the collapsed state and the upright state under the stimulation of ultrasound.

[0009] Optionally, the ultrasound wave is 1-3 MHz wavelength and 30 mW / cm 2 -1000 mW / cm 2 Low-intensity pulsed ultrasound.

[0010] Optionally, the support structure includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

[0011] Optionally, the film includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

[0012] Optionally, the mass of the carbon nanotubes is 2-5wt% of the mass of the shape memory polymer, the mass of the barium titanate is 3-5wt% of the mass of the shape memory polymer, and the mass of the Fe3O4 nanoparticles is 10-15wt% of the mass of the shape memory polymer.

[0013] Optionally, the pore size is 200-500 micrometers, and the porosity of the pores in the support structure is 25-80%.

[0014] In a second aspect, the present invention provides a method for preparing a 4D printed bone tissue scaffold with an adjustable microenvironment, and preparing the 4D printed bone tissue scaffold with an adjustable microenvironment as described in any one of the above, comprising the following steps:

[0015] Design a structural model of the scaffold structure according to the condition of the bone defect, and use a fused deposition model or direct writing 4D printing method to print and shape it to obtain a scaffold structure with holes;

[0016] The film is printed using a light-curing printing method;

[0017] A film is attached to the surface of the support structure.

[0018] Optionally, the step of designing a structural model of the scaffold structure according to the condition of the bone defect, and printing and molding the scaffold structure by a fused deposition model or direct writing 4D printing method to obtain the scaffold structure with holes includes:

[0019] Based on CT scanning and reconstruction software, a 3D printing model of a scaffold structure with holes was designed using 3D design software according to the shape and anatomical structure of the bone defect;

[0020] The 3D printed model is imported into a 3D printer, and the support structure is prepared using a fused deposition or direct writing 4D printing method.

[0021] In a third aspect, the present invention provides an application of a 4D printed bone tissue scaffold with adjustable microenvironment as described in any of the above items in the field of filling bone defects and inducing osteogenesis.

[0022] The beneficial effects of the 4D printed bone tissue scaffold with adjustable microenvironment and its preparation method and application of the present invention are: first, holes are provided on the scaffold structure. During the deformation process of the scaffold structure under stress, the holes can switch between a contact state and a separation state, and the distance between the holes changes. The change in distance will produce a triboelectric effect, and then generate a microcurrent. Along with the generation of the microcurrent, a physical microenvironment conducive to cell growth is constructed, which is conducive to the regeneration of damaged bone tissue; secondly, ultrasound, as a mechanical wave, provides additional mechanical stimulation at the bone defect, which can cause the scaffold structure to be slightly deformed under stress, and can also cause the scaffold structure to produce piezoelectric effect and triboelectric effect, inducing the generation of microcurrent on the surface of the scaffold structure, thereby constructing a physical microenvironment conducive to cell growth, and then facilitating the regeneration of damaged bone tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a microcolumn on a membrane in a collapsed state according to an embodiment of the present invention;

[0024] Figure 2 It is a schematic structural diagram of the micro-pillars on the membrane in an upright state according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0027] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0028] In the related technologies, the mechanical microenvironment around cells plays an important role in the growth, development and differentiation of cells. The mechanical microenvironment includes mechanical pressure, microgravity, magnetic field force, electric field force and extracellular matrix stiffness, which can affect the biological functions of cells by regulating the signal pathways in cells. For example, natural bone has piezoelectric behavior of induced potential under mechanical stress, and the piezoelectric constant is 0.7pC / N-2.3pC / N, which is closely related to the movement of asymmetric collagen molecules and ionic liquids generated by the sliding of collagen fibers. Piezoelectric and triboelectric biomaterials will generate surface charges similar to those on the surface of bones under external stress. Piezoelectric bioscaffold materials are implanted in the site of bone defects to generate stress through physiological loads, thereby generating electrical stimulation and promoting bone tissue generation.

[0029] Low-intensity pulsed ultrasound (LIPUS) is a non-invasive physical therapy used to accelerate bone repair and promote bone healing. As a mechanical wave, LIPUS can provide additional mechanical stimulation at the bone defect site, which can not only activate kinase pathways and upregulate osteogenic protein expression to promote osteogenesis, but also act on piezoelectric and triboelectric biomaterials to produce piezoelectric and triboelectric effects, further promoting bone regeneration. Studies have shown that when LIPUS and piezoelectric biomaterials are used simultaneously in bone tissue engineering, cell proliferation and osteogenic differentiation in vitro and osteogenesis in animal models in vivo are better than using LIPUS or piezoelectric biomaterials alone. Therefore, the introduction of LIPUS, a biophysical stimulus, in bone tissue engineering can not only induce microcurrents on the surface of piezoelectric and triboelectric materials, but also serve as a mechanical stimulus to further promote bone tissue generation. In addition, low-frequency ultrasound can also drive the microstructure on the surface of the scaffold to swing back and forth, thereby constructing a biomechanical microenvironment required for cell growth.

[0030] In view of the problems existing in the above-mentioned related technologies, this embodiment provides a 4D printed bone tissue scaffold with adjustable microenvironment and a preparation method and application thereof.

[0031] A 4D printed bone tissue scaffold capable of adjusting a microenvironment provided in an embodiment of the present invention comprises a scaffold structure and a membrane covering the surface of the scaffold structure, wherein the scaffold structure is provided with holes;

[0032] The holes have a contact state in which the opposite edges are in contact with each other and a separation state in which the opposite edges are not in contact with each other. When the support structure is deformed by force under the stimulation of ultrasound, the holes are configured to switch between the contact state and the separation state.

[0033] In this embodiment, firstly, holes are provided on the support structure. During the deformation process of the support structure under stress, the holes can switch between a contact state and a separation state, and the distance between the holes changes. The change in distance will produce a triboelectric effect, accompanied by the generation of microcurrent, thereby constructing a physical microenvironment conducive to cell growth, and further facilitating the regeneration of damaged bone tissue; secondly, ultrasound, as a mechanical wave, provides additional mechanical stimulation at the bone defect, which can cause the support structure to undergo micro-deformation under stress, and can also cause the support structure to produce piezoelectric effect and triboelectric effect, inducing the generation of microcurrent on the surface of the support structure, thereby constructing a physical microenvironment conducive to cell growth, and further facilitating the regeneration of damaged bone tissue.

[0034] Optionally, a surface of the membrane away from the support structure is provided with micro-pillars, the micro-pillars have a collapsed state and an upright state, and the micro-pillars are configured to switch between the collapsed state and the upright state under the stimulation of ultrasound.

[0035] In this optional embodiment, if Figure 1 and Figure 2 As shown, the surface of the scaffold structure is covered with a membrane having microcolumns. Under the stimulation of ultrasound, the microcolumns on the surface of the membrane will deform. During the repeated uprighting-collapse process, the microcolumns will exert mechanical stimulation on the cells, constructing a physical microenvironment that is conducive to cell growth, thereby inducing bone tissue regeneration.

[0036] Optionally, the ultrasound wave is 1-3 MHz wavelength and 30 mW / cm 2 -1000 mW / cm 2 Low-intensity pulsed ultrasound.

[0037] In this optional embodiment, 1-3 MHz wavelength and 30 mW / cm 2 -1000 mW / cm 2Low-intensity pulsed ultrasound (LIPUS) is a non-invasive physical therapy used to accelerate bone repair and promote bone healing. As a mechanical wave, it provides additional mechanical stimulation at the bone defect, which can not only activate the kinase pathway and upregulate the expression of osteogenic proteins to promote osteogenesis, but also act on the scaffold structure of piezoelectric and triboelectric biomaterials to produce piezoelectric and triboelectric effects, inducing microcurrents on the surface of the scaffold structure, thereby constructing a physical microenvironment that is conducive to cell growth, and then facilitating the regeneration of damaged bone tissue.

[0038] Specifically, low-intensity pulsed ultrasound stimulation is performed for 5-30 minutes. Under the stimulation of ultrasound, the support structure can generate microcurrent, and the microcolumns on the surface of the membrane can vibrate under the stimulation of ultrasound, completing the collapse-upright conversion action.

[0039] Optionally, the support structure includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

[0040] In this optional embodiment, a melt deposition or direct writing 4D printing method is used, with shape memory polymers, carbon nanotubes, barium titanate, and Fe3O4 nanoparticles as the main raw materials. After blending, a printing line for 4D printing is obtained. By utilizing its variable stiffness properties, the bone tissue engineering scaffold structure obtained has a good retention ability. The scaffold structure can be implanted into the body through minimally invasive surgery and unfolded under the stimulation of a magnetic field, etc. The bone tissue scaffold can also be implanted in a state where the shape of the bone defect is uncertain. By utilizing its shape memory effect, the scaffold structure material is in a relatively soft state above the glass transition temperature, in which the bone tissue scaffold can fill the irregular bone defect by itself. Among them, the scaffold structure of triboelectric / piezoelectric materials made of carbon nanotubes can significantly improve its output performance, mainly because of the excellent electrical conductivity and mechanical strength of carbon nanotubes, which helps to improve the generation of triboelectric charges and the efficiency of charge transfer.

[0041] Specifically, the shape memory polymer is one or more of shape memory polylactic acid, shape memory polyurethane, shape memory polycaprolactone, shape memory chitosan, and composites and derivatives thereof.

[0042] Specifically, the particle size of barium titanate is 200-800 nm, the particle size of carbon nanotubes is 20-50 nm, and the particle size of Fe3O4 nanoparticles is 20-50 nm.

[0043] Optionally, the film includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

[0044] In this optional embodiment, the membrane has high precision and is prepared using a photocuring printing method, and is perfectly attached to the surface of the bone tissue scaffold structure under thermal stimulation.

[0045] Optionally, the mass of the carbon nanotubes is 2-5wt% of the mass of the shape memory polymer, the mass of the barium titanate is 3-5wt% of the mass of the shape memory polymer, and the mass of the Fe3O4 nanoparticles is 10-15wt% of the mass of the shape memory polymer.

[0046] In this optional embodiment, after the raw materials in this ratio are blended, the printing wire for 4D printing is prepared, and its variable stiffness property is better, so that the bone tissue engineering scaffold structure retention ability obtained is better.

[0047] Optionally, the pore size is 200-500 micrometers, and the porosity of the pores in the support structure is 25-80%.

[0048] In this optional embodiment, when the support structure is under pressure, the distance between the holes changes, and the distance change will produce a triboelectric effect, thereby generating a microcurrent.

[0049] In a second aspect, the present invention provides a method for preparing a 4D printed bone tissue scaffold with an adjustable microenvironment, and preparing the 4D printed bone tissue scaffold with an adjustable microenvironment as described in any one of the above, comprising the following steps:

[0050] Design a structural model of the scaffold structure according to the condition of the bone defect, and use a fused deposition model or direct writing 4D printing method to print and shape it to obtain a scaffold structure with holes;

[0051] The film is printed using a light-curing printing method;

[0052] A film is attached to the surface of the support structure.

[0053] In this embodiment, the 4D printed bone tissue scaffold with adjustable microenvironment prepared by direct writing 4D printing technology based on three-dimensional laser can well maintain cell activity.

[0054] Optionally, the steps of designing a structural model of the scaffold structure according to the condition of the bone defect, and printing and molding the scaffold structure by a fused deposition model or direct writing 4D printing method to obtain the scaffold structure with holes specifically include:

[0055] Based on CT scanning and reconstruction software, a 3D printing model of a scaffold structure with holes was designed using 3D design software according to the shape and anatomical structure of the bone defect;

[0056] The 3D printed model is imported into a 3D printer, and the support structure is prepared using a fused deposition or direct writing 4D printing method.

[0057] In a third aspect, the present invention provides an application of a 4D printed bone tissue scaffold capable of adjusting the microenvironment as described in any one of the above items in the field of filling bone defects and inducing osteogenesis.

[0058] The present invention is further described below in conjunction with specific embodiments.

[0059] Example 1, the preparation of a 4D printed bone tissue scaffold capable of adjusting the microenvironment comprises the following steps:

[0060] 1. Prepare a 50wt% shape memory polylactic acid solution, add 2wt% of carbon nanotubes, 5wt% of barium titanate, and 15wt% of Fe3O4 nanoparticles, and mix them evenly to obtain solution A.

[0061] 2. Place the solution A obtained in step 1 in a watch glass and evaporate it completely to obtain a block-like solid, which is then crushed.

[0062] 3. Use the crushed material in step 2 to prepare wire for 4D printing, and use 4D printing technology to prepare the support structure.

[0063] Fourth, the crushed material in step 2 is used to prepare a film with microcolumns using photocuring printing technology, and the variable stiffness characteristics of the film are used to perfectly adhere it to the surface of the scaffold structure to obtain a 4D printed bone tissue scaffold with adjustable microenvironment.

[0064] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A 4D printed bone tissue scaffold capable of regulating microenvironment, characterized in that: It comprises a support structure and a film covering the surface of the support structure, wherein the support structure is provided with holes; The hole has a contact state in which the relative edges are in contact with each other and a separation state in which the relative edges are not in contact with each other. When the support structure is deformed by force under the stimulation of ultrasound, the hole is configured to switch between the contact state and the separation state.

2. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 1, characterized in that: A surface of the membrane away from the support structure is provided with micro-pillars, the micro-pillars having a collapsed state and an upright state, and the micro-pillars are configured to switch between the collapsed state and the upright state under the stimulation of ultrasound.

3. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 2, characterized in that: The ultrasonic wave has a wavelength of 1-3 MHz and a power of 30 mW / cm 2 -1000 mW / cm 2 Low-intensity pulsed ultrasound.

4. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 1, characterized in that: The support structure includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

5. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 1, characterized in that: The film includes shape memory polymer, carbon nanotubes, barium titanate and Fe3O4 nanoparticles.

6. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 4 or 5, characterized in that: The mass of the carbon nanotubes is 2-5wt% of the mass of the shape memory polymer, the mass of the barium titanate is 3-5wt% of the mass of the shape memory polymer, and the mass of the Fe3O4 nanoparticles is 10-15wt% of the mass of the shape memory polymer.

7. The 4D printed bone tissue scaffold with adjustable microenvironment according to claim 1, characterized in that: The pore diameter is 200-500 micrometers, and the porosity of the pores on the support structure is 25-80%.

8. A method for preparing a 4D printed bone tissue scaffold capable of adjusting microenvironment, characterized in that: The preparation of the 4D printed bone tissue scaffold with adjustable microenvironment as described in any one of claims 1 to 7 comprises the following steps: Designing a structural model of the scaffold structure according to the condition of the bone defect, and printing and molding it by a fused deposition model or a direct writing 4D printing method to obtain the scaffold structure with holes; The film is printed using a light-curing printing method; A film is attached to the surface of the support structure.

9. The method for preparing a 4D printed bone tissue scaffold with adjustable microenvironment according to claim 8, characterized in that: The step of designing a structural model of the scaffold structure according to the condition of the bone defect, and printing and molding the scaffold structure by a fused deposition or direct writing 4D printing method to obtain the scaffold structure with holes comprises: Based on CT scanning and reconstruction software, a 3D printing model of the scaffold structure with holes is designed using 3D design software according to the shape and anatomical structure of the bone defect; The 3D printed model is introduced into a 3D printer, and the support structure is prepared by a fused deposition or direct writing 4D printing method.

10. Use of a 4D printed bone tissue scaffold with adjustable microenvironment as described in any one of claims 1 to 7 in the field of filling bone defects and inducing osteogenesis.

Images