CN117181554A - Medical titanium alloy screw containing moisture-adhesive coating and preparation method thereof - Google Patents

Abstract

The invention provides a medical titanium alloy screw with a wet adhesive coating and a preparation method thereof. The screw has smooth surface under the dry condition, and can effectively reduce the abrasion between the screw and the bone in the screwing process; the screw has better adhesive force in the wet environment such as tissue fluid, blood and the like, so that the mechanical stability of screw implantation can be improved; the surface coating of the screw can absorb water and expand in the wet environments such as tissue fluid, blood and the like, so that the mechanical stability of the screw is further improved.

Description

Medical titanium alloy screw containing moisture-adhesive coating and preparation method thereof

Technical field

The present invention relates to the technical field of medical devices, and in particular to a medical titanium alloy screw containing a moisture-adhesive coating with stable properties, good biocompatibility and tight bonding force with bones, and a preparation method thereof.

Background technique

Medical titanium alloy screws have good biocompatibility, the elastic modulus is closer to that of bone tissue, there is no interaction with magnetic fields, and they do not affect patients’ MRI and other examinations. They are commonly used biological implants in orthopedic surgeries. It is prone to loosening and poor stability during long-term use. Therefore, whether the surface of titanium alloy screws can be treated to enhance the tight integration between titanium alloy screws and bone tissue after implantation has become a hot topic and a difficulty that needs to be solved urgently for orthopedic researchers at home and abroad. The following are some solutions in the prior art: The patent application number CN202310629279.9 discloses an integrin nano-silver chelating peptide composite coating and its preparation method and application. The titanium sheet or/and titanium nail are washed with distilled water. , soak it in absolute ethanol, then treat it with oxygen plasma, immerse it in a PBS solution containing (DOPA) 4-G5-GRGDS for the first layer of coating, immerse it in medical alcohol for disinfection, and wash away any unattached (DOPA) 4-G5-GRGDS, dried, then soaked in AgNO3 solution and left to stand for the second layer of coating, disinfected and dried, and integrin nanosilver chelates were obtained on the surface of the titanium sheet or/and titanium nails. The peptide composite coating, which modifies medical titanium-based material screws, can be used as an external bone fixation bracket when bone is injured. It not only has strong antibacterial properties, but can also promote osseointegration around the nail track and effectively prevent screw loosening; The patent application number CN201711124373. Texturing, ablation or inducing a micron-scale or nano-scale surface structure composed of multiple rings stacked, which can achieve the effect of one-way friction reduction and reverse friction increase of titanium alloy screws, and can improve the efficiency of screws. Surface biocompatibility. The patent application number CN202210766865.3 discloses biologically fixed pedicle screws and their preparation methods and applications. The biologically fixed pedicle screws are functionally differentiated based on the bone structure and load-bearing mechanical properties of different parts of the vertebral body. The design includes three different functional partition designs: a cortical bone thread with a rough interface is designed at the root of the screw body to connect the cortical bone part of the spine and enhance the bonding strength; a natural-like design is designed at the vertebral body head of the screw. The macroscopic microporous structure of the bone tissue is used to promote the ingrowth of the host bone tissue and increase the bone ingrowth integration ability; a bioactive surface interface with a micro-nano topology is designed on the overall surface of the screw to promote the osteoinduction ability and enhance the integration with the bone tissue. Biofixation of host bone tissue.

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a device that has low friction during implantation, can reduce bone wear, and generates strong adhesion with the bone in a wet environment after implantation to increase the stability of the implant. Wet-adhesion coated medical titanium alloy screws and preparation methods thereof.

In order to achieve the above object, the present invention relates to a method for preparing a medical titanium alloy screw containing a moisture-adhesive coating, which includes the following steps:

(1) Anodizing: Remove the oil stains on the surface of the titanium alloy screws, and then use the titanium alloy screws as the anode and the platinum sheet as the cathode to conduct electrolysis in an ethylene glycol aqueous solution containing ammonium fluoride to generate regular arrangements on the surface of the titanium alloy screws. Titanium dioxide nanotubes of uniform size. After completion, take out the titanium alloy screws, wash and dry them for later use;

(2) UV treatment to form a moisture-containing sticky coating: Soak the anodized medical titanium alloy screws in the surface treatment solution. Take them out after the surface of the titanium alloy screws is fully moistened, irradiate them with UV lamps, and wash them after the surface solidifies. After drying, a hydrogel film is formed on the surface of the titanium alloy screw, that is, a moisture-containing sticky coating. The mass fraction of each component in the surface treatment solution is: 30% acrylic acid, 10%-15% gelatin, 1% N-succinimide acrylate and 0.2% photoinitiator.

Specifically, the preparation method of the surface treatment solution is as follows: dissolving acrylic acid, gelatin, acrylic acid-N-succinimide ester and photoinitiator in deionized water, and vacuum degassing to obtain a surface treatment solution.

Further, the surface treatment solution also includes 0.1% methacrylic anhydride gelatin.

Specifically, in step (1), the mass fraction of NH4F in the ethylene glycol aqueous solution containing ammonium fluoride is 0.5wt%, the volume ratio of distilled water and ethylene glycol is 9:1, and the electrolysis conditions are 60V voltage oxidation for 3 hours.

Specifically, the photoinitiator includes but is not limited to one or more of α-ketoglutarate, 2959, TPO, and 907.

Compared with the prior art, the present invention has the following beneficial effects:

1. The surface of the screw is smooth under dry conditions, which can effectively reduce the wear between the screw and the bone during screwing;

2. Screws have good adhesion in wet environments such as tissue fluid and blood, which can increase the mechanical stability of screw implantation;

3. The surface coating of the screw can absorb water and expand in humid environments such as tissue fluid and blood, further increasing the mechanical stability of the screw;

4. The surface coating is biodegradable and provides operability for the drug sustained release function.

Detailed ways

Figure 1 shows the surface morphology of titanium alloys that have undergone different treatments in Example 1.

Figure 2 shows the friction coefficient of the titanium alloy surface that has undergone different treatments in Example 1 in dry environment and FBS. Among them, untreated means only polishing treatment, oxidation means polishing and oxidation treatment, untreated -10% (15 %) is polished and UV treated, oxidized - 10% (15%) is polished, oxidized and UV treated, 10% (15%) is the concentration of gelatin in the surface treatment solution used for UV treatment.

The present invention will be further described below through specific examples.

Example 1

This embodiment relates to a method for preparing a titanium alloy plate containing a moisture-adhesive coating, which specifically includes the following steps:

(1) Titanium alloy plate polishing: Use 500 mesh, 2000 mesh and 3000 mesh sandpaper to grind the surface of the titanium alloy plate in sequence, remove the outermost passivation layer and grind the surface until smooth to ensure that the surface roughness is basically consistent, and then polish the Clean the titanium alloy plate and dry it in the air before use;

(2) Anodizing: Add 0.5wt% (mass percentage) NH ₄ F and 10% vol (volume ratio) distilled water to ethylene glycol to prepare an electrolyte. Pour the electrolyte into a beaker, stir for 10 minutes, and then ultrasonic for 20 minutes. , use a polished titanium alloy plate as the anode and a platinum plate as the cathode. The distance between the two electrodes is 3-4cm, the voltage is 60V, and oxidized at room temperature for 3 hours; nanotubes are formed on the surface through anodization, and the nanotubes can accommodate the Growth factors and drugs also provide anchor points for subsequent hydrogels and improve the surface binding force of hydrogels;

(3) Configure the surface treatment solution: Dissolve acrylic acid, gelatin, acrylic acid-N-succinimide ester and photoinitiator α-ketoglutarate in deionized water, vacuum deaeration, and determine the quality of each component in the surface treatment solution. The fractions are: 30% acrylic acid, 10% or 15% gelatin, 4% acrylic acid-N-succinimide ester, and 1% alpha-ketoglutaric acid;

(4) Lamination: Use a rubber dropper to drop two drops of surface treatment solution on the surface of the oxidized titanium alloy plate, then gently press the slide on the surface of the titanium alloy plate dripping with the solution, and lean against the slide Its own weight makes the solution evenly cover the surface of the titanium alloy plate. The thickness of the film is controlled by controlling the number of glass slides, and then it is irradiated with UV light for 30 minutes to solidify the solution.

The surface morphology of the polished titanium alloy plate is shown in Figure 1(a). It can be seen that the surface is smooth and flat, and the material itself has a small number of defects. Figure 1(b) shows an anodized titanium alloy plate. It can be seen that there are regularly arranged holes of similar sizes on the surface. A thin film composed of titanium dioxide nanotubes is formed on the surface. After measurement, it is found that the diameter of the nanotubes is between 70 and 70. Between 140nm and the average diameter is around 100nm. Figure 1(c) shows a titanium alloy plate with a hydrogel film formed on the surface. It can be found that the titanium dioxide nanotubes are missing and replaced by a layer of colloidal film. The colloidal film is relatively flat.

Figure 2 shows the friction coefficient between titanium alloy plates processed by different methods and 6mm bone balls prepared from fresh bovine thigh bones under different friction environments. The vertical load applied during the friction process is 20N, the sliding speed is 1mm/s, and the sliding distance is 10mm. Figure 2(a) and (b) show the polished titanium alloy, as well as the titanium alloy that has been polished, oxidized and UV surface modified (the gelatin content in the surface treatment solution is 15% and 10%) in a dry environment and From the friction coefficient under FBS (newborn bovine serum), it can be seen that the friction coefficient changes with time and basically follows the trend of first increasing and then decreasing. Figure 2(c) shows the average friction coefficient of titanium alloys with different treatment methods in dry environment and FBS (newborn bovine serum). It can be seen that the resistance of the treated implants during the implantation process is reduced and the relative sliding is reduced. The wear and tear caused by it achieves the function of increasing resistance in the forward direction and reducing resistance in the reverse direction. Figure 2(d) shows the sliding friction coefficient of titanium alloys with different treatment methods in a dry environment and FBS (newborn bovine serum). Combined with the maximum static friction coefficient, the titanium alloy plate prepared with a wet-stick coating has the largest coefficient of friction in FBS. The static friction coefficient has been significantly improved, which means that the mechanical stability of the implant in the early stage of implantation can be improved.

Under the action of the photoinitiator α-ketoglutarate, ultraviolet light irradiation polymerizes acrylic acid and acrylic acid N-succinimide ester to form a polyacrylic acid N-succinimide ester macromolecular single chain, and then part of the acrylic acid amber The imide ester reacts with the primary amine on gelatin to form amide bonds to complete cross-linking and form a double-stranded macromolecular network hydrogel. After surface treatment, the surface film of the screw under dry conditions is smooth, which will reduce the friction coefficient between the screw surface and the bone tissue surface when the screw is screwed in (the tissue fluid and blood will not have time to enter the contact surface between the screw and the bone when screwing in) , at this time the friction environment is a dry environment), thus reducing the dynamic friction force and thus reducing the wear of bone tissue.

After screwing in, blood and tissue fluid enter the contact surface, causing the friction environment to become a wet environment. In the wet environment, the carboxyl groups on the surface film of the screw first form hydrogen bonds with the two contact surfaces in the water to produce a smaller adhesion force. , then the polyacrylic acid in the membrane absorbs the interface water and expands. The change in membrane volume makes the screw interface and bone interface more closely connected. At the same time, the N-succinimide ester on the membrane can form a covalent bond with the amino group on the surface of the bone tissue. This produces a larger adhesion force, thus achieving strong adhesion between the implant and bone tissue and increasing the mechanical stability of the implant.

In addition, the use of biodegradable gelatin makes the surface coating of the screw partially degradable, and there are many regularly arranged and uniformly sized titanium dioxide nanotubes on the surface of the anodized titanium alloy. The nanotubes can be filled with drugs or bone-promoting growth factors. The coating acts as an encapsulating film, which creates a slow-release mechanism.

The feasibility of the above method is demonstrated through the characterization of titanium alloy plates. On this basis, medical titanium alloy screws with moisture-adhesive coating were prepared.

Example 2

This embodiment relates to a method for preparing medical titanium alloy screws containing a moisture-adhesive coating, which includes the following steps:

(1) Anodizing: Remove the oil stain on the surface of the titanium alloy screw, then use the titanium alloy screw as the anode and the platinum sheet as the cathode, in an ethylene glycol aqueous solution containing ammonium fluoride (the mass fraction of NH4F in the solution is 0.5wt%, distilled water and ethylene glycol (the volume ratio is 9:1), oxidize at 60v voltage for 3 hours, take out the oxidized titanium alloy screws, wash and dry them for later use;

(2) Configure the surface treatment solution: Dissolve acrylic acid, gelatin, acrylic acid-N-succinimide ester and photoinitiator α-ketoglutarate in deionized water, vacuum deaeration, and determine the mass of each component in the surface treatment solution. The fractions are: 30% acrylic acid, 10% gelatin, 1% acrylic acid-N-succinimide ester, and 0.2% alpha-ketoglutarate;

(3) UV surface treatment to form a hydrogel film with moisture-containing adhesive coating: Then put the anodized medical titanium alloy screw into the surface treatment solution and soak it for half an hour. After the screw surface is fully moistened, take it out and use a UV lamp. Irradiate for 20 minutes, wash and dry after the surface is cured.

Example 3

This embodiment is the same as Embodiment 2 except step (2).

(2) Prepare surface treatment solution: Dissolve acrylic acid, gelatin, acrylic acid-N-succinimide ester, methacrylic anhydride gelatin and photoinitiator α-ketoglutarate in deionized water, vacuum degassing, and surface treatment The mass fraction of each component in the solution is: 30% acrylic acid, 15% gelatin, 1% acrylic acid-N-succinimide ester, 0.1% methacrylic anhydride gelatin and 0.2% photoinitiator TPO .

Example 4

This embodiment is the same as Embodiment 2 except step (2).

(2) Prepare surface treatment solution: Dissolve acrylic acid, gelatin, acrylic acid-N-succinimide ester, methacrylic anhydride gelatin and photoinitiator α-ketoglutarate in deionized water, vacuum degassing, and surface treatment The mass fraction of each component in the solution is: 30% acrylic acid, 10% gelatin, 1% acrylic acid-N-succinimide ester, 0.1% methacrylic anhydride gelatin and 0.2% α-ketopentane Diacid.

Compared with Example 1, a small amount of methacrylic anhydride gelatin is added to the surface treatment solution in this example, which has excellent biocompatibility, and can be stimulated by ultraviolet light or visible light to form a curing reaction suitable for cell growth and A differentiated and strong three-dimensional structure can not only improve the mechanical properties of hydrogels, but also promote cell growth.

Claims (5)

1. A method for preparing medical titanium alloy screws containing a moisture-adhesive coating, which is characterized in that it includes the following steps: (1) Anodizing: Remove the oil stains on the surface of the titanium alloy screws, and then use the titanium alloy screws as the anode and the platinum sheet as the cathode to conduct electrolysis in an ethylene glycol aqueous solution containing ammonium fluoride to generate regular arrangements on the surface of the titanium alloy screws. Titanium dioxide nanotubes of uniform size. After completion, take out the titanium alloy screws, wash and dry them for later use; (2) UV treatment to form a moisture-containing sticky coating: Soak the anodized medical titanium alloy screws in the surface treatment solution. Take them out after the surface of the titanium alloy screws is fully moistened, irradiate them with UV lamps, and wash them after the surface solidifies. After drying, a hydrogel film is formed on the surface of the titanium alloy screw, that is, a moisture-containing sticky coating. The mass fraction of each component in the surface treatment solution is: 30% acrylic acid, 10%-15% gelatin, 1% N-succinimide acrylate and 0.2% photoinitiator. 2. The preparation method of medical titanium alloy screws containing moisture-adhesive coating according to claim 1, characterized in that the configuration method of the surface treatment solution is: acrylic acid, gelatin, acrylic acid-N-succinimide The ester and photoinitiator are dissolved in deionized water and vacuum degassed to obtain a surface treatment solution. 3. The preparation method of medical titanium alloy screws containing moisture-adhesive coating according to claim 1, characterized in that the surface treatment solution further includes 0.1% methacrylic anhydride gelatin. 4. The preparation method of medical titanium alloy screws containing moisture-adhesive coating according to claim 1, characterized in that the mass fraction of NH4F in the solution of the ethylene glycol aqueous solution containing ammonium fluoride in step (1) is 0.5 wt%, the volume ratio of distilled water and ethylene glycol is 9:1, and the electrolysis conditions are 60V voltage oxidation for 3h. 5. The preparation method of medical titanium alloy screws containing moisture-adhesive coating according to claim 1, characterized in that the photoinitiator is one or more of α-ketoglutaric acid, 2959, TPO, and 907 .