Lantern-like deployment-locked and self-powered coating of bone implants and methods of making same

Abstract

The application discloses a bone implant with a lampshade-expanding locking and self-energy-supplying coating and a preparation method thereof, and belongs to the medical implant field. The bone implant is designed according to the contraction structure of a lampshade, is in an elongated form below a martensite phase transition temperature, and is in an open lampshade form above an austenite phase transition temperature. The bone implant realizes self-adaptive expansion and surface locking in a marrow cavity by using the super-elasticity and shape memory effect of a memory alloy, and provides instant three-dimensional mechanical stability beyond traditional bone plates and intramedullary nails. The surface of the bone implant is coated with a functional gradient coating, which can actively capture biochemical energy and mechanical energy in the body, and intelligently and time-sequentially regulate growth factor release and cell behavior according to the biochemical energy and the mechanical energy, so that the continuous glucose metabolism and physiological activities in the body are directly converted into electric energy and control signals for driving bone healing, and energy self-provision and logic autonomy are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical implant, in particular to a bone implant with a lampshade-like unfolding locking and self-powered coating and a preparation method thereof. BACKGROUND

[0002] The clinical repair of large segmental bone defects faces two core challenges: one is to achieve long-term stable fixation of the implant, and the other is to promote rapid and reliable biological integration between the host bone and the implant.

[0003] In terms of fixation, traditional technology mainly relies on bone plates and screws or long intramedullary nails for bridging fixation. This method has problems such as large surgical trauma, extensive soft tissue and periosteal stripping, damage to bone blood supply and fixation stability, severe dependence on screw holding force in cortical bone, poor effect for patients with osteoporosis or short bone stumps, and stress shielding caused by rigid fixation devices, which is not conducive to bone healing and remodeling. Some existing expandable stents are not suitable for bone shaft fixation scenarios that bear complex multidimensional mechanical loads.

[0004] In terms of promoting bone integration, the current mainstream relies on biologically inert porous structures (such as porous tantalum and 3D printed porous titanium) or simple biological coatings (such as hydroxyapatite) on the surface of the implant. These are passive designs that only provide physical space or a transmission interface for bone growth, and cannot actively guide and accelerate the healing process. Although some studies have attempted to load growth factors (such as BMP-2) into implants, they have faced problems such as burst release, uncontrollable time efficiency, dependence on external devices for activation, or reliance on unsustainable battery power. Existing technologies lack a mechanism for autonomous, sustainable, and intelligent response to physiological signals in the body, resulting in a slow and uncertain bone integration process, especially in cases where blood supply is poor or the patient's own repair ability is weak. SUMMARY

[0005] To solve the technical problems of unstable mechanical properties and unsustainable energy supply of bone implants in the prior art, the present application provides a bone implant with a lampshade-like unfolding locking and self-powered coating and a preparation method thereof, which can achieve immediate, reliable, and biomechanically compatible fixation of the bone implant through minimally invasive methods, and can also construct an intelligent biological interface on the bone implant itself that does not require external power supply, can perceive the environment, and automatically execute repair procedures, thereby simultaneously solving the two difficult problems of mechanical stability and biological integration, and significantly improving the repair effect and clinical reliability of large segmental bone defects.

[0006] The specific solutions are as follows:

[0007] The first aspect of the present application provides a bone implant with a lampshade-like unfolding locking and self-powered coating, comprising:

[0008] Two bases are symmetrically arranged, and the bases are fixed to human bones;

[0009] A screw is arranged, and two ends of the screw are connected with the two bases respectively, and the screw can rotate around its axis, and the upper half and the lower half of the screw are reversely threaded;

[0010] Two nuts are symmetrically arranged, and the two nuts are sleeved on the upper half and the lower half of the screw respectively;

[0011] A plurality of support arms are evenly distributed in the circumferential direction and take the screw as the center, and two ends of each support arm are fixed to the two nuts respectively, the support arm is made of a shape memory alloy strip, the support arm is in a first memory shape below a martensite phase transition temperature, the first memory shape is a straight strip close to the screw, and the support arm is in a second memory shape above an austenite phase transition temperature, and the second memory shape is an arc shape arching away from the screw;

[0012] The surface of the bone implant has a functionally graded coating.

[0013] Further, the functionally graded coating comprises, from inside to outside, a piezoelectric fiber base layer, an enzyme dynamic response active layer and an electric response factor release surface layer.

[0014] Further, the second memory shape of the support arm is an arc shape with a diameter 10%-20% larger than that of a target host bone marrow cavity.

[0015] Further, the base is a bearing, and an outer ring of the bearing is fixed to the human bone, and an inner ring of the bearing is fixed to the end of the screw.

[0016] Further, the bone implant further comprises two wrenches, and the two wrenches are symmetrically fixed to the two ends of the screw, and the wrenches are located between the nuts and the bases.

[0017] Further, the bone implant further comprises a bolt, and the bolt is locked in the side wall of the nut through the support arm.

[0018] The second aspect of the present application provides a preparation method of the lantern unfolding locking and self-powered coating bone implant in the first aspect, and the preparation method comprises the following steps:

[0019] S1, the design and construction of the bone implant are performed according to the lantern folding structure;

[0020] S2, the support arm of the bone implant is constrained to the first memory shape and cooled, so that the support arm is converted into a flexible martensite phase;

[0021] S3, the functionally graded coating is constructed on the surface of the bone implant, and the preparation of the bone implant is completed.

[0022] Further, the functional gradient coating in step S3 comprises three layers, from inside to outside, a piezoelectric fiber base layer, an enzyme dynamic response active layer, and an electric response factor release surface layer.

[0023] The preparation method of the piezoelectric fiber base layer is as follows:

[0024] Dissolve the poly-L-lactic acid particles in a mixed solvent of chloroform and N,N-dimethylformamide to prepare a poly-L-lactic acid solution with a concentration of 8-12wt%, and the volume ratio of chloroform to N,N-dimethylformamide is 7:3;

[0025] Add barium titanate nanoparticles to the above poly-L-lactic acid solution, and the addition amount is 15-25wt% of the mass of the poly-L-lactic acid particles;

[0026] Stir the mixed solution formed after adding the barium titanate nanoparticles and then perform ultrasonic treatment to ensure uniform dispersion of the barium titanate nanoparticles and form a stable electrospinning precursor solution;

[0027] Inject the electrospinning precursor solution into a syringe pump, fix the bone implant on a grounded receiver, and spray the electrospinning precursor solution on all surfaces of the bone implant to obtain the piezoelectric fiber base layer.

[0028] Further, the preparation method of the enzyme dynamic response active layer is as follows:

[0029] Disperse the mesoporous carbon nanospheres in a PBS solution with a pH of 7.4, add glucose oxidase and horseradish peroxidase, so that the final concentrations of glucose oxidase and horseradish peroxidase are 5mg / mL and 2mg / mL respectively, and slowly oscillate and incubate at 4℃ to allow the glucose oxidase and horseradish peroxidase to be fully absorbed into the mesopores and on the surface of the mesoporous carbon nanospheres;

[0030] Add glutaraldehyde for cross-linking, centrifuge and wash with a PBS solution, and then disperse the mesoporous carbon nanospheres in the PBS solution to obtain an enzyme-carbon sphere composite dispersion liquid with a concentration of 20mg / mL;

[0031] Dissolve sodium alginate in a PBS solution to prepare a 2.0wt% solution to obtain liquid A;

[0032] Dissolve gelatin in a PBS solution to prepare a 4.0wt% solution, and cool to room temperature to obtain liquid B;

[0033] Mix liquid A and liquid B in a volume ratio of 1:1 to obtain AB mixed liquid, and add the above enzyme-carbon sphere composite dispersion liquid to the AB mixed liquid at a proportion of 10% of the total volume, and mix gently;

[0034] Put the bone implant into the spraying cabin, uniformly spray the AB mixed solution to the surface of the bone implant covered with the piezoelectric fiber base layer, atomize the calcium chloride solution and glutaraldehyde vapor into the spraying cabin while spraying, and obtain the enzyme dynamic response active layer after spraying is completed.

[0035] Further, the preparation method of the electric response factor release surface layer is as follows:

[0036] Dissolve chitosan in 1% acetic acid solution to prepare a 1.5wt% solution, add polypyrrole nanowires with a mass of 30% of the mass of chitosan, ultrasonic dispersion, and adjust the pH to 6.0 to obtain a conductive pre-polymer solution;

[0037] Slowly add VEGF and BMP-2 into the conductive pre-polymer solution in turn, and the total volume of VEGF and BMP-2 accounts for 5% of the conductive pre-polymer solution;

[0038] Vertically immerse the bone implant with the piezoelectric fiber base layer and the enzyme dynamic response active layer on the surface into the above-mentioned mixed solution, stay for 60 seconds, then pull out the liquid surface at the same speed, so that a uniform liquid film is formed on the surface, then immediately place the bone implant in the saturated sodium tripolyphosphate vapor, so that the chitosan is ionically crosslinked and gelled, then air dry, form a solid composite gel film, and obtain the electric response factor release surface layer.

[0039] The beneficial effects of the present application are as follows:

[0040] The lantern-shaped bone implant of the present application utilizes the super-elasticity and shape memory effect of the memory alloy to realize self-adaptive expansion and planar locking in the medullary cavity, and provides immediate three-dimensional mechanical stability beyond traditional bone plates and intramedullary nails, and the matching self-powered functional gradient coating can actively capture biochemical energy and mechanical energy in the body, and intelligently and time-sequentially regulate growth factor release and cell behavior;

[0041] The functional gradient coating of the present application converts the continuous glucose metabolism and physiological activity in the body into electric energy and control signals for driving bone healing through the enzyme dynamic-piezoelectric coupling mechanism, and realizes energy self-provision and logic autonomy.

[0042] The excellent initial stability of the present application allows the patient to perform safe rehabilitation training early, and the training itself can enhance the osteogenic treatment signals of the functional gradient coating through the piezoelectric effect, forming a positive cycle of more activity and more healing. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the bone implant of the present application.

[0044] Figure 2 It is a shape memory recovery schematic diagram of the bone implant of the present application.

[0045] Figure 3 Figure 1 is a schematic view of the shape of the bone implant after implantation.

[0046] In the present application, the reference signs are as follows:

[0047] 1, bone implant; 11, base; 12, wrench; 13, screw rod; 14, nut; 15, bolt; 16, support arm. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] Please refer to Figure 1 The present embodiment discloses a bone implant 1 with lantern-like unfolding and locking and self-powered coating, which comprises a base 11, a screw rod 13, a nut 14, a support arm 16, a bolt 15 and a wrench 12.

[0050] The base 11 is provided in two, and the two bases 11 are symmetrically arranged. Preferably, the base 11 is a bearing. When the bone implant 1 is implanted into the human body, the outer ring of the bearing is fixedly connected with the human bone, and the inner ring of the bearing can rotate freely.

[0051] The screw rod 13 is provided in one, and its core function is to provide axial guidance for unfolding. The two ends of the screw rod 13 are fixedly connected with the inner rings of the two bearings, so that the screw rod 13 can rotate synchronously with the rotation of the inner rings of the bearings. The screw rod 13 is made of medical titanium alloy, is hollow inside, and has precise threads on the surface. The threads are divided into two sections, and the upper half of the threads and the lower half of the threads are reverse threads.

[0052] The nut 14 is provided in two, and the two nuts 14 are respectively sleeved on the upper half of the threads and the lower half of the threads of the screw rod 13. When the screw rod 13 rotates, the nut 14 will move along the screw rod 13. The nut 14 is a hexagonal nut 14.

[0053] The support arm 16 is provided in six, and the six support arms 16 are uniformly distributed in the circumferential direction with the screw rod 13 as the center. The six support arms 16 correspond to the six side faces of the nut 14 respectively, and the two ends of each support arm 16 are fixedly connected with two nuts 14 respectively. In the present embodiment, the support arm 16 is fixedly connected with the nut 14 through the bolt 15. A threaded hole is formed in the center position of each side face of the nut 14, and the threaded hole does not penetrate through the side wall of the nut 14. The bolt 15 is locked in the threaded hole in the side wall of the nut 14 after penetrating through the support arm 16, so as to realize the fixed connection of the support arm 16 with the nut 14.

[0054] The support arm 16 is made of a shape memory alloy strip, which has a first memory shape at a temperature below the martensitic transformation temperature, the first memory shape being a straight strip shape close to the screw rod 13, so that the entire bone implant 1 has an elongated shape, which is convenient for implanting the bone implant 1 into the body; and has a second memory shape at a temperature above the austenitic transformation temperature, the second memory shape being an arc shape arching away from the screw rod 13. Preferably, the support arm 16 is made of a medical-grade Nitinol alloy with excellent super-elasticity and shape memory performance, preferably a nickel-rich composition such as NiTi-01, and the austenitic transformation completion temperature (Af) is set to be between 28°C and 32°C, which is slightly lower than the core body temperature of the human body (≈37°C), which ensures that the material is always in a strong austenitic state in the body environment, and can exhibit super-elasticity.

[0055] The second memory shape of the support arm 16 (i.e. after the support arm 16 is fully deployed) is an arc line with a curvature larger than the diameter of the target host bone marrow cavity by 10% to 20%, and the arc line is a involute, so that when the support arm 16 is fully deployed, a radial compressive stress is applied to the inner wall of the bone cortex.

[0056] The wrench 12 has a total of two, and the external shape of the wrench 12 is the same as that of a hexagonal nut, and the wrench 12 is used to facilitate the wrench operation, and the screw rod 13 is driven to rotate by the wrench acting on the wrench 12. The two wrenches 12 are symmetrically fixed at the two ends of the screw rod 13, and the wrench 12 is located between the nut 14 and the base 11.

[0057] Please refer to Figure 2 With Figure 3 The locking workflow of the bone implant 1 of the present application is as follows:

[0058] Before the operation, the entire bone implant 1 is cooled in 0-10°C sterile normal saline, so that the support arm 16 is completely converted into a flexible martensitic phase, and in this state, the support arm 16 is constrained to be a straight strip shape (i.e. the first memory shape) by using a mounting tool, as shown in the left side of the figure in Figure 2 At this time, the diameter of the bone implant 1 is the smallest, and it can pass through a small incision and a bone marrow cavity. Then the bone implant 1 is loaded into a delivery sheath tube and pushed to the bone defect area. After reaching the predetermined position, the delivery sheath tube is withdrawn, and due to the strong super-elasticity of the nickel-titanium alloy, the support arm 16 in the martensitic phase will immediately attempt to restore its intermediate shape before being constrained (i.e. an arc shape that is not fully deployed), and this restoring force drives the support arm 16 to automatically and gently preliminarily deploy until it contacts the endometrium, achieving preliminary centering and stabilization. It is worth mentioning that this process does not require external mechanical driving.

[0059] After implantation into the body, the temperature of the bone implant 1 is rapidly raised to 37℃ by blood and tissue fluid. When the temperature exceeds the austenite phase transition starting temperature (As, about 20-25℃) and eventually exceeds Af (28-32℃), the support arm 16, especially the distal self-locking segment (i.e. the end connected with the nut 14), begins to recover to its inherent, larger curvature second memory shape, as shown in the right side of the figure in Figure 2 Due to the diameter of the second memory shape being larger than the actual anatomical diameter of the medullary cavity, the recovery movement of the self-locking segment is mechanically limited by the inner wall of the bone cortex. The huge recovery force generated by the shape memory effect is converted into a continuous, radially outward, dynamic compressive stress acting on the inner wall of the bone cortex, and the size of the force is determined by the phase transition driving force of the shape memory alloy and the constraint reaction force of the bone wall, forming a self-adaptive mechanical balance. The involute curved surface design of the support arm 16 ensures maximum surface contact with the irregular endosteum, and the pressure is evenly distributed.

[0060] Due to the inconsistent shape memory deformation of each support arm 16, an external force is needed to adjust it. An additional, slight axial displacement is provided to the support arm 16 by slightly tightening the screw rod 13 (e.g. rotating 1-2 turns), which is rotated synchronously by rotating the wrench 12, and then the two nuts 14 move towards each other on the screw rod 13, until the geometric configuration of the support arm 16 reaches the optimum, the shape memory recovery force is stable, the stress imbalance caused by the shape memory force is eliminated, the shape memory recovery force is stabilized in the pre-set optimal range, and the final locking is completed.

[0061] The surface of the bone implant 1 has a functional gradient coating, which includes three layers. From the inside to the outside, the first layer is a piezoelectric fiber base layer, the second layer is an enzyme dynamic response active layer, and the third layer is an electric response factor release surface layer.

[0062] The embodiment also provides a preparation method of the lampshade-like unfolding and self-powered coating bone implant 1, for preparing the lampshade-like unfolding and self-powered coating bone implant 1, which specifically comprises the following steps:

[0063] S1, inspired by the lampshade contraction structure, the design of the bone implant 1 is carried out, and the bone implant 1 is constructed according to the size of the large bone defect of the patient.

[0064] S2, the support arm 16 of the bone implant 1 is constrained into a straight strip (first memory shape), and is cooled in sterile normal saline at 0-10℃, so that the support arm 16 is converted into a flexible martensite phase.

[0065] S3, a functional gradient coating is constructed on the surface of the bone implant 1, and the preparation of the bone implant 1 is completed.

[0066] The functionally graded coating in step S3 includes three layers, from inside to outside, the first layer is a piezoelectric fiber base layer, the second layer is an enzyme dynamic response active layer, and the third layer is an electric response factor release surface layer.

[0067] The preparation method of the first layer of the functionally graded coating, the piezoelectric fiber base layer, is as follows:

[0068] Dissolve the poly-L-lactic acid particles in a mixed solvent of chloroform and N,N-dimethylformamide to prepare a poly-L-lactic acid solution with a concentration of 8-12 wt%, and the volume ratio of the mixed solvent is chloroform:N,N-dimethylformamide=7:3;

[0069] Add barium titanate nanoparticles to the above poly-L-lactic acid solution, and the addition amount is 15-25 wt% of the mass of the poly-L-lactic acid particles;

[0070] Place the mixed solution formed after adding the barium titanate nanoparticles above in a magnetic stirrer, stir at 40℃ for 12 hours, and then perform ultrasonic treatment for 30 minutes to ensure uniform dispersion of the barium titanate nanoparticles and form a stable electrospinning precursor solution;

[0071] Inject the electrospinning precursor solution into a syringe pump equipped with a 21G blunt stainless steel needle, fix the bone implant 1 on a rotatable grounded receiver as a collection device, and set the key parameters: applied voltage: +18kV (needle) / -5kV (receiver), bolus speed: 1.0mL / h, receiving distance: 18cm, ambient temperature and humidity: 25℃, relative humidity <30%; start the device, spray the electrospinning precursor solution on all surfaces of the bone implant 1 through the syringe pump, and uniformly deposit the L-lactic acid / barium titanate composite nanofibers on all surfaces of the bone implant 1, and by controlling the slow rotation of the grounded receiver and the electrospinning time (usually 2-4 hours), a porous and interwoven fiber layer with a thickness of about 10-30μm and a fiber diameter in the range of 300-800nm is obtained;

[0072] Finally, place the bone implant 1 with the deposited fiber layer in a vacuum drying oven and dry at 40℃ for 24 hours to completely remove the residual solvent, and obtain the first layer of the functionally graded coating, the piezoelectric fiber base layer.

[0073] The preparation method of the second layer of the functionally graded coating, the enzyme dynamic response active layer, is as follows:

[0074] Disperse the mesoporous carbon nanospheres in a PBS solution (phosphate buffer solution) with a pH of 7.4, add glucose oxidase and horseradish peroxidase to make the final concentrations of glucose oxidase and horseradish peroxidase 5mg / mL and 2mg / mL respectively, and slowly shake and incubate at 4℃ to allow the glucose oxidase and horseradish peroxidase to be fully absorbed into the mesopores and on the surface of the mesoporous carbon nanospheres;

[0075] Add glutaraldehyde (final concentration 0.1%) and crosslink for 1 hour, then centrifugal clean with PBS solution for three times, and then re-disperse the mesoporous carbon nanospheres in PBS solution to obtain the enzyme-carbon nanosphere composite dispersion with a concentration of 20 mg / mL;

[0076] Dissolve sodium alginate in PBS solution to obtain a 2.0 wt% solution as A solution;

[0077] Dissolve gelatin in PBS solution to obtain a 4.0 wt% solution cooled to room temperature as B solution;

[0078] Mix A solution and B solution in a volume ratio of 1:1 to obtain AB mixed solution, and then add the enzyme-carbon nanosphere composite dispersion into the AB mixed solution at a proportion of 10% of the total volume, and mix gently to avoid air bubbles;

[0079] Place the bone implant 1 in a spraying cabin, and use a low-pressure gas flow atomizing spray gun to uniformly spray the AB mixed solution onto the surface of the bone implant 1 which has been covered with a piezoelectric fiber base layer, wherein the parameters are: air pressure 0.2 MPa, nozzle diameter 0.3 mm, spraying distance 15 cm, and ambient temperature 20-25°C; while spraying, 0.1 M calcium chloride solution and 25% glutaraldehyde vapor are atomized and introduced into the spraying cabin for gentle crosslinking of gelatin, which is completed within 5 minutes, so that the sodium alginate is instantaneously ionically crosslinked, the gelatin is slightly chemically crosslinked, a stable interpenetrating network hydrogel is formed, and the enzyme-carbon nanosphere composite is firmly embedded therein, and an enzyme dynamic response active layer is obtained after spraying, which has a wet thickness of about 50-100 μm.

[0080] The third layer of the functionally graded coating, i.e., the preparation method of the electric response factor release surface layer, is as follows:

[0081] Dissolve chitosan in 1% acetic acid solution to obtain a 1.5 wt% solution, add polypyrrole nanowires (about 80 nm in diameter) with a mass of 30% of the mass of chitosan, ultrasonic dispersion, and adjust the pH to 6.0 with NaOH solution to obtain a uniform and slightly sticky conductive pre-polymer solution;

[0082] Slowly add VEGF (vascular endothelial growth factor) and BMP-2 (bone morphogenetic protein-2) into the conductive pre-polymer solution in sequence, and the total volume of VEGF and BMP-2 accounts for 5% of the conductive pre-polymer solution;

[0083] The bone implant 1 with the surface covered by the piezoelectric fiber base layer and the enzyme dynamic response active layer is vertically immersed in the above mixed solution at a speed of 100 mm / min, stays for 60 seconds, and then is uniformly pulled out of the liquid surface at the same speed to form a uniform liquid film on the surface. Then the bone implant 1 is immediately placed in a saturated sodium tripolyphosphate vapor to cause ion cross-linking gelation of chitosan, and then is air-dried at 25°C and a humidity of 50% for 12 hours to form a solid composite gel film, thereby obtaining an electric response factor release surface layer.

[0084] Preferably, after the third layer coating is prepared, the bone implant 1 with the three-layer coating is placed in a 4°C environment for 24 hours to balance the moisture and structure of each layer and between the layers. Low-dose ethylene oxide is used for sterilization, and the sterilization cycle needs to strictly control the temperature (<40°C) and humidity to maximize the protection of enzyme activity and growth factor activity. Under sterile conditions, the bone implant 1 is packaged in a sealed packaging bag filled with inert gas and stored in a 4°C refrigerator until use.

[0085] The principle of preparation of the functional gradient coating is that when the functional gradient coating contacts glucose in the tissue fluid, a cascade enzyme reaction is started. This reaction process is accompanied by electron transfer and proton consumption, and can continuously generate an ion gradient and a weak oxidation-reduction current (μA level) in the local microenvironment of the coating. The intensity of the biochemical derived electrical signal is positively correlated with the degree of local metabolic activity (glucose concentration).

[0086] The intelligent release logic of the functional gradient coating is as follows:

[0087] Early stage (inflammation / vascular stage): The metabolism of the postoperative wound site is vigorous, the glucose concentration is high, and the enzyme dynamic response active layer generates a strong microcurrent. The microcurrent preferentially triggers VEGF with a shallow anchor and low bond energy, realizes the early active release of VEGF, and stimulates the proliferation and migration of vascular endothelial cells to promote the growth of new blood vessels into the pores of the bone implant 1.

[0088] Middle and late stage (repair / osteogenesis stage): With the subsidence of inflammation, the glucose concentration returns to the baseline, and the enzyme bioelectricity weakens. At this time, the mechanical load produced by the patient's rehabilitation training becomes dominant. The piezoelectric fiber base layer of the bone implant 1 is activated by micro-motion to generate intermittent high-voltage pulses. The pulses, in cooperation with the baseline microcurrent, are sufficient to trigger the release of BMP-2 with a deeper anchor and higher bond energy. BMP-2 is a strong osteoinductive factor. At the same time, the piezoelectric pulse itself directly electrically stimulates cell osteogenic differentiation. Under the dual action, new bone formation around the bone implant 1 is promoted to achieve biological fixation.

[0089] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application, the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the present application.

Claims

1. A bone implant with a lantern-like deployment locking and self-powered coating, characterized in that, The bone implant (1) comprises: two bases (11) symmetrically arranged and fixed to the human body bone; a screw rod (13) having two ends connected with the two bases (11) respectively, and being capable of rotating around its axis, the upper half and the lower half of the screw rod (13) being reverse threads; two nuts (14) symmetrically arranged and sleeved on the upper half thread and the lower half thread of the screw rod (13) respectively; a plurality of support arms (16) evenly distributed in the circumferential direction and taking the screw rod (13) as the center, two ends of each support arm (16) being fixed to the two nuts (14) respectively, the support arm (16) being made of a shape memory alloy belt, the shape memory alloy belt being in a first memory shape below the martensite phase transition temperature, the first memory shape being a straight strip shape close to the screw rod (13), the shape memory alloy belt being in a second memory shape above the austenite phase transition temperature, the second memory shape being an arc shape arching away from the screw rod (13); The surface of the bone implant (1) has a functional gradient coating, the functional gradient coating comprises, from inside to outside, a piezoelectric fiber base layer, an enzyme dynamic response active layer, and an electric response factor release surface layer. The preparation method of the piezoelectric fiber base layer is as follows: Poly-L-lactic acid particles are dissolved in a mixed solvent of chloroform and N,N-dimethylformamide to prepare a poly-L-lactic acid solution with a concentration of 8-12wt%, the volume ratio of the mixed solvent being chloroform:N,N-dimethylformamide=7:3; Barium titanate nanoparticles are added to the poly-L-lactic acid solution, the amount of the barium titanate nanoparticles being 15-25wt% of the mass of the poly-L-lactic acid particles; The mixed solution obtained after adding the barium titanate nanoparticles is stirred and then subjected to ultrasonic treatment to ensure uniform dispersion of the barium titanate nanoparticles and form a stable electrospinning precursor solution; The electrospinning precursor solution is injected into a syringe pump, the bone implant (1) is fixed on a grounded receiver, and the electrospinning precursor solution is sprayed on all surfaces of the bone implant (1) to obtain the piezoelectric fiber base layer. The preparation method of the enzyme dynamic response active layer is as follows: Mesoporous carbon nanospheres are dispersed in a PBS solution with a pH of 7.4, and glucose oxidase and horseradish peroxidase are added to make the final concentrations of the glucose oxidase and the horseradish peroxidase be 5mg / mL and 2mg / mL respectively, and the glucose oxidase and the horseradish peroxidase are incubated at 4°C under slow shaking to be fully absorbed into the mesopores and the surface of the mesoporous carbon nanospheres; Glutaraldehyde is added for cross-linking, and the mesoporous carbon nanospheres are washed and centrifuged with a PBS solution to be re-dispersed in the PBS solution to obtain an enzyme-carbon sphere composite dispersion liquid with a concentration of 20mg / mL; Sodium alginate is dissolved in a PBS solution to prepare a 2.0wt% solution to obtain A liquid; Gelatin is dissolved in a PBS solution to prepare a 4.0wt% solution, and the solution is cooled to room temperature to obtain B liquid; A and B liquids are mixed at a volume ratio of 1:1 to obtain AB mixed liquid, and the enzyme-carbon sphere composite dispersion liquid is added to the AB mixed liquid at a proportion of 10% of the total volume, and the mixture is gently mixed. The bone implant (1) is placed in a spraying cabin, and the AB mixed solution is uniformly sprayed to the surface of the bone implant (1) covered with the piezoelectric fiber base layer, while the calcium chloride solution and glutaraldehyde vapor are atomized and introduced into the spraying cabin, and the enzyme dynamic response active layer is obtained after the spraying is completed; The preparation method of the electric response factor release surface layer is as follows: Chitosan is dissolved in 1% acetic acid solution to prepare a 1.5wt% solution, polypyrrole nanowires are added in an amount of 30% of the mass of chitosan, ultrasonic dispersion is performed, and the pH is adjusted to 6.0 to obtain a conductive pre-polymer solution; VEGF and BMP-2 are slowly added into the conductive pre-polymer solution in sequence, and the total volume of VEGF and BMP-2 accounts for 5% of the volume of the conductive pre-polymer solution; The bone implant (1) with the piezoelectric fiber base layer and the enzyme dynamic response active layer on the surface is vertically immersed in the above mixed solution for 60 seconds, then is uniformly pulled out of the liquid surface at the same speed, so that a uniform liquid film is formed on the surface, then the bone implant (1) is immediately placed in saturated sodium tripolyphosphate vapor to cause ion cross-linking gelation of chitosan, and then is air-dried to form a solid composite gel film, thereby obtaining the electric response factor release surface layer.

2. The lampshade-like deployed locking and self-powered coating bone implant of claim 1, wherein, The second memory shape of the support arm (16) is an arc shape which is 10% to 20% larger than the diameter of the target host bone marrow cavity.

3. The lampshade-like deployed, locking, and self-energating coated bone implant of claim 1, wherein, The base (11) is a bearing, the outer ring of which is fixed to the human body bone, and the inner ring of which is fixed to the end of the screw rod (13).

4. The lampshade-like deployed, locking, and self-energating coated bone implant of claim 1, wherein, The two wrenches (12) are symmetrically fixed to the two ends of the screw rod (13), and the wrench (12) is located between the nut (14) and the base (11).

5. The lampshade-like deployed, lock-in-place, and self-powered coating of a bone implant of claim 1, wherein, The bolt (15) is locked in the side wall of the nut (14) through the support arm (16).

6. A method of making a lantern-deployed locking and self-energating coated bone implant according to any one of claims 1-5, characterized in that, The method comprises the following steps: S1, the design and construction of the bone implant (1) is performed by imitating the lantern contraction structure; S2, the support arm (16) of the bone implant (1) is constrained to a first memory shape and cooled, so that the support arm (16) is converted into a flexible martensite phase; S3, a functional gradient coating is constructed on the surface of the bone implant (1), and the preparation of the bone implant (1) is completed.

7. The method of making a lantern-unfolding locking and self-energating coated bone implant of claim 6, wherein, The functional gradient coating in step S3 comprises three layers, which are, from inside to outside, a piezoelectric fiber base layer, an enzyme dynamic response active layer, and an electric response factor release surface layer; The preparation method of the piezoelectric fiber base layer is as follows: Poly-L-lactic acid particles are dissolved in a mixed solvent of chloroform and N,N-dimethylformamide to prepare a poly-L-lactic acid solution with a concentration of 8-12wt%, and the volume ratio of the mixed solvent is chloroform:N,N-dimethylformamide=7:3; Barium titanate nanoparticles are added to the above poly-L-lactic acid solution, and the addition amount is 15-25wt% of the mass of the poly-L-lactic acid particles; The mixed solution formed after adding the barium titanate nanoparticles is stirred and then ultrasonically treated to ensure uniform dispersion of the barium titanate nanoparticles, thereby forming a stable electrospinning precursor solution; The electrospinning precursor solution is injected into a syringe pump, the bone implant (1) is fixed on a grounded receiver, and the electrospinning precursor solution is sprayed to all surfaces of the bone implant (1), thereby obtaining the piezoelectric fiber base layer.

8. The method of making a lantern-unfolding locking and self-energizing coated bone implant according to claim 7, wherein, The preparation method of the enzyme dynamic response active layer is as follows: The mesoporous carbon nanospheres are dispersed in a PBS solution with pH 7.4, and glucose oxidase and horseradish peroxidase are added to make the final concentrations of the glucose oxidase and the horseradish peroxidase 5 mg / mL and 2 mg / mL respectively, and the glucose oxidase and the horseradish peroxidase are incubated at 4 ℃ under slow shaking to be fully adsorbed into the mesopores and on the surface of the mesoporous carbon nanospheres; Glutaraldehyde is added for cross-linking, and the mesoporous carbon nanospheres are cleaned by centrifugation and re-dispersed in a PBS solution to obtain an enzyme-carbon sphere composite dispersion with a concentration of 20 mg / mL; Sodium alginate is dissolved in a PBS solution to prepare a 2.0 wt% solution to obtain A liquid; Gelatin is dissolved in a PBS solution to prepare a 4.0 wt% solution, and the solution is cooled to room temperature to obtain B liquid; A liquid and B liquid are mixed at a volume ratio of 1:1 to obtain AB mixed liquid, and the enzyme-carbon sphere composite dispersion is added into the AB mixed liquid at a proportion of 10% of the total volume, and the mixture is gently mixed; The bone implant (1) is placed in a spraying cabin, and the AB mixed liquid is uniformly sprayed onto the surface of the bone implant (1) covered with the piezoelectric fiber base layer, and calcium chloride solution and glutaraldehyde vapor are atomized and introduced into the spraying cabin at the same time, and an enzyme dynamic response active layer is obtained after spraying.

9. The method of making a lantern-unfolding locking and self-energating coated bone implant of claim 8, wherein, The preparation method of the electric response factor release surface layer is as follows: Chitosan is dissolved in a 1% acetic acid solution to prepare a 1.5 wt% solution, and polypyrrole nanowires are added at a mass of 30% of the mass of the chitosan, and the mixture is ultrasonically dispersed, and the pH is adjusted to 6.0 to obtain a conductive pre-polymer solution; VEGF and BMP-2 are slowly added into the conductive pre-polymer solution in sequence, and the total volume of the VEGF and the BMP-2 accounts for 5% of the conductive pre-polymer solution; The bone implant (1) with the piezoelectric fiber base layer and the enzyme dynamic response active layer on the surface is vertically immersed in the mixed liquid for 60 seconds, and then is pulled out of the liquid surface at the same speed to form a uniform liquid film on the surface, and then the bone implant (1) is immediately placed in saturated sodium tripolyphosphate vapor to cause ionic cross-linking gelation of the chitosan, and then is air-dried to form a solid composite gel film, and an electric response factor release surface layer is obtained.

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