Degradable zinc alloy anastomosis nail and preparation method thereof

Abstract

The application belongs to the technical field of medical instrument design and production, and provides a degradable zinc alloy anastomosis nail and a preparation method thereof. The anastomosis nail is formed by adding trace amounts of magnesium, lithium and silver into zinc as a matrix to form an alloy, pouring to obtain an alloy ingot, and then performing hot extrusion and cold drawing on the ingot to obtain zinc alloy wire, and annealing between passes. After the zinc alloy wire is formed, sandpaper roughening, phosphating, mechanical micro-roughening are sequentially performed to build a surface pretreatment layer, a Zn-phytic acid complex anchoring layer, a chitosan ion barrier layer crosslinked by gentian violet and a polylactic acid / magnesium carbonate composite controlled release outer layer are sequentially formed on the pretreated surface, the alloy degradation is synergistically regulated by complex anchoring, ion barrier and outer layer slow release, the metal ion burst release is reduced, the local corrosion product accumulation is inhibited and the acid-base fluctuation is buffered, and the postoperative support and gradual absorption requirements are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of medical device design and production, and relates to a degradable zinc alloy anastomosis nail and a preparation method thereof. BACKGROUND

[0002] As a key implant component of surgical staplers, anastomosis nails are widely used for cutting, anastomosis and fixation of digestive tract, blood vessels and lung tissue, etc. The existing clinical anastomosis nails are mostly made of inert metal materials such as titanium alloy and stainless steel, which can provide reliable forming strength and tissue clamping force, but they may cause image artifacts, foreign body reactions or long-term irritation when left in the body for a long time, and there is a burden of secondary removal or long-term follow-up in some scenarios. In order to reduce the risk of permanent implantation, absorbable polymer anastomosis nails have been proposed, but the polymer materials are limited in forming stiffness, shear resistance and creep resistance, and may easily cause insufficient support and deformation rebound in parts with high tissue load or long healing period, affecting the stability of anastomosis.

[0003] Degradable metal materials provide a path for anastomosis nails to have both strength and absorbability, among which magnesium-based alloys degrade relatively quickly and may be accompanied by hydrogen evolution and local alkalization, leading to gas accumulation and tissue irritation risk; iron-based materials degrade slowly and are difficult to match the tissue healing period; zinc-based materials have potential balance in mechanical processability and degradation rate, but pure zinc has low strength and hardness, and may easily cause local corrosion, accumulation of corrosion products and local enrichment of metal ions during degradation, affecting tissue compatibility and degradation consistency. In order to improve the performance of zinc-based materials, the common method is to control the organization through alloying and hot working to improve strength and plasticity, but the solid solution of alloying elements and the precipitation of second phases will bring about the difference in electrochemical potential, making the micro-electric couple effect more significant. If the organization and surface state are not controlled, pitting, groove corrosion or stage accelerated corrosion may still occur.

[0004] On the other hand, surface treatment and coating regulation are used to improve the interfacial behavior of zinc alloy in body fluid environment. Traditional single polymer coating can delay the entry of corrosion medium to some extent, but its adhesion to the metal surface is limited, and interface failure may occur during service due to hydration, shear load or corrosion product growth; at the same time, the hydrolysis of some polyester coatings may cause local acidification, further inducing corrosion behavior fluctuation. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a degradable zinc alloy anastomosis nail and a preparation method thereof, aiming to solve the problems of traditional metal anastomosis nails long-term residual causing foreign body reaction and image interference, and the insufficient strength and forming stability of existing degradable materials. The anastomosis nail is formed by alloying zinc as a base body with magnesium, lithium and silver, homogenizing by melting under inert atmosphere, extruding and drawing into wire, and adjusting the structure by annealing, so that the zinc alloy wire has good plasticity and consistency in nail making, and then the surface is polished and cleaned and coated with a degradable polymer film, so as to obtain an anastomosis nail with mechanical reliability and degradability, thereby meeting the needs of actual production.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a degradable zinc alloy anastomosis nail, wherein the mass fraction of Mg in the zinc alloy is 0-3.0wt.%, the mass fraction of Li is 0-3.0wt.%, the mass fraction of Ag is 0-3.0wt.%, and the mass fraction of Mg, Li and Ag is not 0, and the rest is Zn; the anastomosis nail comprises a zinc alloy wire made of the zinc alloy, a surface pretreatment layer arranged on the surface of the zinc alloy wire and a functional coating, wherein the surface pretreatment layer comprises a roughened surface formed by sandpaper polishing and a phosphate conversion layer; the functional coating comprises a Zn-phytic acid complex anchoring layer, a cross-linked chitosan layer and a polylactic acid / magnesium carbonate composite controlled release layer from inside to outside.

[0008] In a second aspect, the present application provides a preparation method of a degradable zinc alloy anastomosis nail, comprising:

[0009] Step (1) according to the composition ratio of zinc alloy, weigh the Zn, Mg, Li and Ag raw materials, put the weighed zinc alloy raw materials into a crucible, and put the crucible into a vacuum furnace;

[0010] Step (2) after the charging is completed, the melting furnace is vacuumed and argon is flushed to ensure the argon atmosphere in the furnace;

[0011] Step (3) start heating, heat to the first temperature, continue to heat after stirring the alloy liquid with the mechanical stirring rod of the melting furnace, and pour to obtain a Zn-Mg-Li-Ag alloy cast rod;

[0012] Step (4) the Zn-Mg-Li-Ag alloy cast rod obtained in step (3) is subjected to rod organization regulation and zinc alloy rod material is prepared, specifically: the Zn-Mg-Li-Ag alloy cast rod is subjected to homogenizing annealing, one-time hot extrusion, water quenching after heat preservation, two-time hot extrusion, swaging and grading annealing in sequence to obtain a zinc alloy rod material;

[0013] Step (5) cold drawing the zinc alloy rod obtained in step (4), annealing between passes, obtaining zinc alloy wire, sandpaper polishing, phosphate chemical treatment and mechanical micro-roughening treatment on the zinc alloy wire in turn, then cleaning and drying the zinc alloy wire to obtain the treated zinc alloy wire;

[0014] Step (6) on the surface of the zinc alloy wire treated in step (5), forming a Zn-phytic acid complex anchoring layer, dipping and coating chitosan solution and drying to form a chitosan coating layer, immersing the zinc alloy wire with the chitosan coating layer into gentian violet solution for crosslinking to form a crosslinked chitosan layer, washing and cleaning the zinc alloy wire with the crosslinked chitosan layer to remove unbound gentian violet residues after crosslinking, then dipping and coating polylactic acid solution containing magnesium carbonate particles and drying to form a polylactic acid / magnesium carbonate composite controlled release layer, then making nails and sterilizing to obtain a degradable zinc alloy anastomosis nail.

[0015] Zinc as the base metal provides the main continuous phase, magnesium and lithium enter the zinc matrix in the form of alloying and change the crystal defects and phase composition, silver participates in the organization construction in the form of solid solution and precipitated phase and introduces the electrochemical potential difference. In the stage of heating and holding, mechanical stirring breaks the stratification caused by thermal convection and density difference, shortens the diffusion path and weakens the concentration boundary layer, thereby reducing the local electrochemical heterogeneity caused by subsequent solidification segregation. The subsequent pouring and solidification belongs to a non-equilibrium solidification process, zinc-based crystals grow first, alloying elements are distributed at the solid-liquid interface and enriched between dendrites, and finally form a microstructure state coexisting with zinc matrix and alloying element-rich regions; silver tends to form silver-rich phases or intermetallic phase regions with zinc, and magnesium and lithium are distributed in the form of solid solution atoms and fine second phases near the grain boundaries. In the subsequent rod organization regulation stage, the casting rod is first homogenized and annealed and cooled in the furnace, so that the concentration gradient of interdendritic segregation is weakened under solid-state diffusion conditions, and the local electrochemical difference caused by composition inhomogeneity during subsequent thermal deformation is reduced.

[0016] The hot extrusion stage changes the morphology and distribution of the second phase by thermal deformation and diffusion processes, the thermoplastic flow makes the segregation zone between the as-cast dendrites elongated, broken and redistributed, the grain boundary and subgrain boundary density are restructured, and the grain orientation is textured. After the first hot extrusion, the heat preservation water quenching is implemented, so that part of the alloying elements are retained in the solid solution state; then the heat preservation and furnace cooling at a lower temperature are implemented, so that the precipitation and redistribution under the solid state diffusion condition occur, thereby adjusting the coupling state of the dispersed precipitated phase, dislocation and substructure. The second hot extrusion further strengthens the directional plastic flow and texture formation, the rotary forging introduces the cumulative strain by radial pressing and promotes the second phase to be broken and refined, and changes the spatial distribution thereof; the staged annealing makes the recovery and partial recrystallization occur and releases the residual stress, and simultaneously promotes the precipitated phase and defect structure to be stable. The cold drawing and pass annealing, the cold drawing increases the dislocation density and introduces the strain inhomogeneous zone, increases the high-energy defects and metastable structure in the lattice. The pass annealing makes the dislocation recover, part of the grains recrystallize and release the residual stress, and simultaneously promotes the alloying elements to be redistributed under the solid state diffusion condition, and the size and interval of the fine precipitated phase tend to be stable.

[0017] Sand paper polishing removes surface contamination layer, processes oxide layer and weakly combined corrosion precursor film, and then phosphate chemical treatment is carried out, metal surface occurs anodic dissolution and local pH change and induces phosphate and zinc ion to generate insoluble phosphate deposit layer at the interface, reduces the effective flux of chloride ions and other corrosive ions. Mechanical micro-roughening treatment, on the one hand, reconfigures the surface morphology of the conversion film to form a multi-scale concave-convex structure, on the other hand, increases the actual specific surface area and mechanical embedding effect to enhance the shear resistance and anti-peeling ability of the subsequent coating, thereby reducing the interface failure risk of the coating in the early service. On the zinc alloy wire after surface pretreatment, a Zn-phytic acid complex anchoring layer is first constructed. The phytic acid molecule contains a polyphosphate group, which can coordinate and multi-point adsorb with the surface zinc ion, oxide / hydroxide site and metal site in the phosphate conversion film under aqueous conditions, forming an interface complex network mainly with metal-phosphate group coordination bond, on the one hand, reducing the effective activity of free zinc ions at the interface, inhibiting the sudden increase of local anodic dissolution rate, on the other hand, providing a transition interface containing phosphate groups and metal sites for the subsequent chitosan layer, improving the adhesion basis of the organic layer on the inorganic surface and reducing the tendency of debonding caused by the interface hydration layer. Then, the chitosan solution is immersed and dried to form a chitosan coating. The amine and hydroxyl groups on the chitosan segment can form ionic association and hydrogen bond network with the phosphate groups of the phytic acid complex layer during the curing process, and can also coordinate and electrostatically adsorb with the residual coordination sites on the metal surface, thereby forming a continuous ionic barrier layer on the anchoring layer. Then, when the zinc alloy wire with chitosan coating is immersed in gentian violet solution for crosslinking treatment, the dye molecule as a positively charged polycyclic aromatic structure can form ionic association and multi-point action with the chitosan segment. A polylactic acid / magnesium carbonate composite controlled release layer is constructed outside the crosslinked chitosan layer, and the polylactic acid mainly in ester bond skeleton undergoes hydrolysis in water environment, and the membrane layer gradually evolves from polymer continuous phase to porous structure, and the hydrolysis product causes the local environment to be acidified.

[0018] As a preferred technical solution of the present application, in step (2), the vacuum degree of the vacuum is not more than 4 Pa.

[0019] As a preferred technical solution of the present application, in step (3), the first temperature is 450-650℃, for example, it can be 450℃, 470℃, 490℃, 510℃, 530℃, 550℃, 570℃, 590℃, 610℃, 630℃ or 650℃, but not limited to the listed values, other values not listed in this range are also applicable.

[0020] In some optional embodiments, the first temperature holding time is 20-40 min, for example, it can be 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0021] In some optional embodiments, the mechanical stirring rod stirs the alloy liquid for 3-10 min, for example, it can be 3.0 min, 3.7 min, 4.4 min, 5.1 min, 5.8 min, 6.5 min, 7.2 min, 7.9 min, 8.6 min, 9.3 min or 10.0 min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0022] In some optional embodiments, the continued holding time is 5-30 min, for example, it can be 5 min, 7.5 min, 10 min, 12.5 min, 15 min, 17.5 min, 20 min, 22.5 min, 25 min, 27.5 min or 30 min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0023] As a preferred technical solution of the present application, in step (4), the homogenization annealing is annealing at 260-320℃ for 2-6h and then furnace cooling. For example, it can be annealing at (260, 266, 272, 278, 284, 290, 296, 302, 308, 314 or 320)℃ for (2.0, 2.4, 2.8, 3.2, 3.6, 4.0, 4.4, 4.8, 5.2, 5.6 or 6.0)h and then furnace cooling, but not only limited to the listed values, other values not listed in the range are also applicable.

[0024] In some optional embodiments, the temperature of the first hot extrusion is 230-290℃, the extrusion ratio is 30-70, and the extrusion speed is 3-10 mm / s. For example, it can be that the temperature is (230, 236, 242, 248, 254, 260, 266, 272, 278, 284 or 290)℃, the extrusion ratio is (30, 34, 38, 42, 46, 50, 54, 58, 62, 66 or 70), and the extrusion speed is (3.0, 3.7, 4.4, 5.1, 5.8, 6.5, 7.2, 7.9, 8.6, 9.3 or 10.0)mm / s, but not only limited to the listed values, other values not listed in the range are also applicable.

[0025] In some optional embodiments, the holding water quenching is holding at 300-330 °C for 10-30 min, then water quenching, and then holding at 120-170 °C for 1-4 h, and then furnace cooling. For example, it can be holding at (300, 303, 306, 309, 312, 315, 318, 321, 324, 327, or 330) °C for (10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30) min, then water quenching, and then holding at (120, 125, 130, 135, 140, 145, 150, 155, 160, 165, or 170) °C for (1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7, or 4.0) h, and then furnace cooling, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0026] In some optional embodiments, the secondary hot extrusion is performed at 210-250 °C, with an extrusion ratio of 6-15, and an extrusion speed of 2-8 mm / s. For example, it can be performed at (210, 214, 218, 222, 226, 230, 234, 238, 242, 246, or 250) °C, with an extrusion ratio of (6, 6.9, 7.8, 8.7, 9.6, 10.5, 11.4, 12.3, 13.2, 14.1, or 15), and an extrusion speed of (2.0, 2.6, 3.2, 3.8, 4.4, 5.0, 5.6, 6.2, 6.8, 7.4, or 8.0) mm / s, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0027] In some optional embodiments, the diameter reduction rate of the rotary swaging is 20-45%, for example, it can be 20%, 22.5%, 25%, 27.5%, 30%, 32.5%, 35%, 37.5%, 40%, 42.5%, or 45%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0028] In some optional embodiments, the annealing is: first-stage annealing at 240-280℃ for 6-15min, second-stage annealing at 140-170℃ for 40-120min, and furnace cooling after the second-stage annealing. For example, it can be: first-stage annealing at (240, 244, 248, 252, 256, 260, 264, 268, 272, 276 or 280)℃ for (6, 6.9, 7.8, 8.7, 9.6, 10.5, 11.4, 12.3, 13.2, 14.1 or 15)min, second-stage annealing at (140, 143, 146, 149, 152, 155, 158, 161, 164, 167 or 170)℃ for (40, 48, 56, 64, 72, 80, 88, 96, 104, 112 or 120)min, and furnace cooling after the second-stage annealing, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0029] As a preferred technical solution of the present application, in step (5), the annealing temperature is 180-330℃, for example, it can be 180℃, 195℃, 210℃, 225℃, 240℃, 255℃, 270℃, 285℃, 300℃, 315℃ or 330℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0030] In some optional embodiments, the diameter of the zinc alloy wire is 0.2-0.4mm, for example, it can be 0.2mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm, 0.3mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm or 0.4mm, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0031] In some optional embodiments, the sandpaper polishing is: polishing the surface of the zinc alloy wire with 3000# and 5000# sandpaper in sequence.

[0032] In some optional embodiments, the phosphating treatment is to treat the zinc alloy wire in a phosphating solution to form a phosphating layer on the surface of the zinc alloy wire, the thickness of the phosphating layer is 1-3 μm, the phosphating solution includes phosphoric acid, zinc nitrate, sodium nitrate and sodium nitrite as solvents, wherein the concentration of phosphoric acid is 10-30 g / L, the concentration of zinc nitrate is 5-20 g / L, the concentration of sodium nitrate is 5-15 g / L, and the concentration of sodium nitrite is 0.5-2.0 g / L; the phosphating treatment is carried out at 25-60 °C for 3-12 min, and then the zinc alloy wire is rinsed with deionized water and dried. For example, the zinc alloy wire can be treated in a phosphating solution to form a phosphating layer on the surface of the zinc alloy wire, the thickness of the phosphating layer is (1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or 3.0) μm, the phosphating solution includes phosphoric acid, zinc nitrate, sodium nitrate and sodium nitrite as solvents, wherein the concentration of phosphoric acid is (10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30) g / L, the concentration of zinc nitrate is (5, 6.5, 8, 9.5, 11, 12.5, 14, 15.5, 17, 18.5 or 20) g / L, the concentration of sodium nitrate is (5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) g / L, and the concentration of sodium nitrite is (0.5, 0.65, 0.8, 0.95, 1.1, 1.25, 1.4, 1.55, 1.7, 1.85 or 2.0) g / L; the phosphating treatment is carried out at (25, 28.5, 32, 35.5, 39, 42.5, 46, 49.5, 53, 56.5 or 60) °C for (3, 3.9, 4.8, 5.7, 6.6, 7.5, 8.4, 9.3, 10.2, 11.1 or 12) min, and then the zinc alloy wire is rinsed with deionized water and dried, but not only limited to the listed values, other values not listed in the range are also applicable.

[0033] In some optional embodiments, the mechanical micro-roughening treatment makes the surface roughness Ra of the zinc alloy wire 0.8-2.5 μm, for example, the surface roughness Ra of the zinc alloy wire can be (0.8, 0.97, 1.14, 1.31, 1.48, 1.65, 1.82, 1.99, 2.16, 2.33 or 2.5) μm, but not only limited to the listed values, other values not listed in the range are also applicable.

[0034] As a preferred technical solution of the present invention, in step (6), after forming the Zn-phytic acid complex anchoring layer, a cross-linked chitosan layer is formed and then a polylactic acid / magnesium carbonate composite controlled-release layer is formed.

[0035] In some optional embodiments, the formation of the Zn-phytic acid complex anchoring layer includes immersing the treated zinc alloy wire in a 0.5-2.0 wt.% phytic acid aqueous solution for 10-30 min, removing it and drying it at 60°C for 20-40 min, so that the thickness of the Zn-phytic acid complex anchoring layer is 0.2-1.0 μm. For example, the treated zinc alloy wire can be immersed in a 0.5, 0.65, 0.8, 0.95, 1.1, 1.25, 1.4, 1.55, 1.7, 1.85, or 2.0 wt.% phytic acid aqueous solution for 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30 min, and then dried at 60℃ for 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, or 40 min to achieve a Zn-phytic acid complex anchoring layer thickness of 0.2, 0.28, 0.36, 0.44, 0.52, 0.6, 0.68, 0.76, 0.84, 0.92, or 1.0 μm. However, this is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the chitosan solution contains 0.8-1.5 wt.% chitosan and 0.8-1.2 wt.% acetic acid. For example, the chitosan mass fraction may be (0.8, 0.87, 0.94, 1.01, 1.08, 1.15, 1.22, 1.29, 1.36, 1.43, or 1.5) wt.% and the acetic acid mass fraction may be (0.8, 0.84, 0.88, 0.92, 0.96, 1.0, 1.04, 1.08, 1.12, 1.16, or 1.2) wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the cross-linked chitosan layer is formed by immersing the zinc alloy wire on which the chitosan coating is dried into a film into a gentian violet solution with a gentian violet mass fraction of 0.2-0.6 wt.%, and the solvent of the gentian violet solution is an ethanol aqueous solution with an ethanol volume fraction of 20-50%, and the thickness of the cross-linked chitosan layer obtained after the cross-linking treatment is 1-4 μm. For example, the gentian violet mass fraction in the gentian violet solution can be (0.2, 0.24, 0.28, 0.32, 0.36, 0.4, 0.44, 0.48, 0.52, 0.56 or 0.6) wt.%, the solvent of the gentian violet solution is an ethanol aqueous solution with an ethanol volume fraction of (20%, 23%, 26%, 29%, 32%, 35%, 38%, 41%, 44%, 47% or 50%), and the thickness of the cross-linked chitosan layer obtained after the cross-linking treatment is (1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7 or 4.0) μm, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0038] In some optional embodiments, the elution cleaning includes: placing the zinc alloy wire on which the cross-linked chitosan layer is formed into an ethanol aqueous solution with an ethanol volume fraction of 20-50% for elution for 5-15 min, changing the solution 2-4 times during the elution, placing the zinc alloy wire into deionized water for rinsing for 5-15 min, changing the solution 2-5 times during the rinsing, and then drying at 40-60 °C for 20-60 min. For example, the zinc alloy wire can be placed into an ethanol aqueous solution with an ethanol volume fraction of (20%, 23%, 26%, 29%, 32%, 35%, 38%, 41%, 44%, 47% or 50%) for elution for (5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) min and changing the solution (2, 3 or 4) times, placed into deionized water for rinsing for (5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) min and changing the solution (2, 3, 4 or 5) times, and then dried at (40, 42, 44, 46, 48, 50, 52, 54, 56, 58 or 60) °C for (20, 24, 28, 32, 36, 40, 44, 48, 52, 56 or 60) min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0039] In some alternative embodiments, the polylactic acid solution containing the magnesium carbonate microparticles is formed by adding magnesium carbonate microparticles having a D50 of 0.5-3 μm, for example, the D50 of the magnesium carbonate microparticles can be (0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, or 3.0) μm, but is not limited to the recited values, and other values not recited within the range are also applicable.

[0040] In some alternative embodiments, the mass fraction of polylactic acid in the polylactic acid solution is 1-2 wt.%, for example, it can be 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, or 2 wt.%, but is not limited to the recited values, and other values not recited within the range are also applicable.

[0041] In some alternative embodiments, the mass ratio of the magnesium carbonate microparticles to the polylactic acid solution is (1-2): 100, for example, it can be (1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2): 100, but is not limited to the recited values, and other values not recited within the range are also applicable.

[0042] In some alternative embodiments, the residence time of the dip coating is 10-60 s, the pulling speed is 1-10 mm / s, and the number of dip coating is 1-3 times. For example, the residence time of the dip coating can be (10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60) s, the pulling speed can be (1, 1.9, 2.8, 3.7, 4.6, 5.5, 6.4, 7.3, 8.2, 9.1, or 10) mm / s, and the number of dip coating can be (1, 2, or 3.0) times, but is not limited to the recited values, and other values not recited within the range are also applicable.

[0043] Compared with the prior art, the application has the beneficial effects that: the application takes the degradable zinc alloy wire as the matrix, improves the forming stability and mechanical consistency of the zinc alloy wire through the organization regulation of melting composition homogenization, extrusion, drawing and annealing, reduces the interface pollution and weak film influence through the composite pretreatment of roughening, chemical formation and micro-roughening, enhances the adhesion and peeling resistance of the subsequent coating, forms a stable coordination interface on the metal surface through the phytic acid complex anchoring layer, inhibits the pitting tendency caused by local electrochemical difference, provides an ion barrier and limits the migration of water and chloride ions through the cross-linked chitosan layer, and the outer layer of polylactic acid and magnesium carbonate composite controlled release structure releases the permeation and buffers the acidic degradation products, so that the degradation rate is regulated in stages, and the ion burst release and corrosion product accumulation risk are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 A Zn-Mg-Li-Ag alloy ingot provided for example 1 of the application is shown in the figure;

[0045] Figure 2 A zinc alloy wire provided for example 1 of the application is shown in the figure;

[0046] Figure 3 A degradable zinc alloy anastomosis needle provided for example 1 of the application is shown in the figure. DETAILED DESCRIPTION

[0047] The technical solutions of the application will be described in detail below with specific examples and their accompanying drawings. The examples described herein are specific embodiments of the application, which are used to illustrate the concept of the application; these descriptions are all explanatory and exemplary, and should not be understood as limiting the embodiments of the application and the protection scope of the application. In addition to the examples described herein, those skilled in the art can also employ other technical solutions that are obvious based on the content disclosed in the claims and the specification of the present application, which include technical solutions that make any obvious substitutions and modifications to the examples described herein.

[0048] The chemical reagents used in the examples and comparative examples of the application are all commercially available goods, without any further purification treatment.

[0049] Example 1

[0050] The present example provides a degradable zinc alloy anastomosis needle and a preparation method thereof, specifically comprising:

[0051] A degradable zinc alloy anastomosis needle, the mass fraction of Mg in the zinc alloy is 0.1wt.%, the mass fraction of Li is 3.0wt.%, the mass fraction of Ag is 0.1wt.%, and the rest is Zn;

[0052] The preparation method comprises:

[0053] (1) According to the component proportion of the zinc alloy, raw materials of Zn, Mg, Li and Ag are weighed and put into a crucible, and the crucible is put into a vacuum furnace;

[0054] (2) After the charging is completed, the smelting furnace is vacuumed and argon is flushed to ensure an argon atmosphere in the furnace, and the vacuum degree of the vacuuming is not more than 4 Pa;

[0055] (3) Heating is started, and the temperature is raised to 450℃ and kept for 40 min. After the alloy liquid is stirred for 3 min by using the mechanical stirring rod of the smelting furnace, it is continuously kept for 30 min, and then the Zn-Mg-Li-Ag alloy cast rod is poured;

[0056] (4) The Zn-Mg-Li-Ag alloy cast rod obtained in step (3) is subjected to rod organization regulation and zinc alloy rod is prepared, specifically: the Zn-Mg-Li-Ag alloy cast rod is subjected to homogenizing annealing, primary hot extrusion, water quenching after heat preservation, secondary hot extrusion, swaging and staged annealing in sequence to obtain the zinc alloy rod, the homogenizing annealing is annealing at 260℃ for 6 h and then furnace cooling; the temperature of the primary hot extrusion is 230℃, the extrusion ratio is 70, and the extrusion speed is 3 mm / s; the water quenching after heat preservation is water quenching after heat preservation at 330℃ for 10 min, and then furnace cooling after heat preservation at 170℃ for 1 h; the secondary hot extrusion is carried out at 250℃, the extrusion ratio is 6, and the extrusion speed is 8 mm / s; the diameter reduction rate of the swaging is 20%; the staged annealing is: the first stage annealing is annealing at 280℃ for 6 min, the second stage annealing is annealing at 170℃ for 40 min, and then furnace cooling after the second stage annealing is completed;

[0057] (5) The zinc alloy rod obtained in step (4) is cold drawn, and annealing treatment is carried out between passes, the temperature of the annealing treatment is 180℃, and the zinc alloy wire with a diameter of 0.4 mm is obtained, the zinc alloy wire is sequentially subjected to sandpaper polishing, phosphate chemical treatment and mechanical micro-roughening treatment, then the zinc alloy wire is cleaned and dried to obtain the treated zinc alloy wire, the surface of the zinc alloy wire is polished by using 3000# and 5000# sandpaper in sequence, the phosphate chemical treatment is that the zinc alloy wire is placed in a phosphate chemical solution to form a phosphate chemical layer on the surface of the zinc alloy wire, the thickness of the phosphate chemical layer is 3 μm, the phosphate chemical solution uses deionized water as a solvent and includes, by concentration, phosphoric acid 10 g / L, zinc nitrate 20 g / L, sodium nitrate 5 g / L and sodium nitrite 2.0 g / L; the phosphate chemical treatment is carried out at 25℃ for 12 min, and the zinc alloy wire is rinsed with deionized water and dried after the phosphate chemical treatment; the zinc alloy wire is subjected to mechanical micro-roughening treatment after the phosphate chemical treatment, and the surface roughness Ra of the zinc alloy wire is 0.8 μm;

[0058] (6) the zinc alloy wire after step (5) is sequentially subjected to: forming a Zn-phytic acid complex anchoring layer, immersing a chitosan solution and drying to form a chitosan coating layer, immersing the zinc alloy wire with the chitosan coating layer into a gentian violet solution for crosslinking to form a crosslinked chitosan layer, after the crosslinking is completed, eluting and cleaning the zinc alloy wire with the crosslinked chitosan layer to remove unbound gentian violet residues, then immersing a polylactic acid solution containing magnesium carbonate particles and drying to form a polylactic acid / magnesium carbonate composite controlled release layer, then performing nail making and sterilization to obtain a degradable zinc alloy anastomosis nail, the forming of the Zn-phytic acid complex anchoring layer comprises immersing the treated zinc alloy wire into a 2.0 wt.% aqueous phytic acid solution for 10 min, and after being taken out, drying at 60℃ for 40 min, so that the thickness of the Zn-phytic acid complex anchoring layer is 0.2 μm, the mass fraction of chitosan in the chitosan solution is 0.8 wt.%, and the mass fraction of acetic acid is 1.2 wt.%, the mass fraction of gentian violet in the gentian violet solution is 0.2 wt.%, the solvent of the gentian violet solution is an ethanol aqueous solution, the volume fraction of ethanol is 50%, the thickness of the crosslinked chitosan layer obtained after crosslinking treatment is 4 μm, the eluting and cleaning comprises: placing the zinc alloy wire with the crosslinked chitosan layer into an ethanol aqueous solution with an ethanol volume fraction of 20% for elution for 15 min, changing the solution twice during the elution, then placing it into deionized water for rinsing for 5 min, changing the solution 5 times during the rinsing, then drying at 60℃ for 20 min, the polylactic acid solution containing magnesium carbonate particles is formed by adding magnesium carbonate particles into a polylactic acid solution, the mass fraction of polylactic acid in the polylactic acid solution is 2 wt.%, the D50 of the magnesium carbonate particles is 0.5 μm, and the mass ratio of the magnesium carbonate particles to the polylactic acid solution is 1:100; the residence time of the immersing is 60 s, the pulling speed is 1 mm / s, and the immersing is performed for 3 times.

[0059] Figure 1 A Zn-Mg-Li-Ag alloy ingot provided in the embodiment is shown in the figure; Figure 2 A zinc alloy wire provided in the embodiment is shown in the figure; Figure 3 A degradable zinc alloy anastomosis nail provided in the embodiment is shown in the figure.

[0060] Embodiment 2

[0061] The embodiment provides a degradable zinc alloy anastomosis nail and a preparation method thereof, and specifically comprises the following steps:

[0062] A degradable zinc alloy anastomosis nail, the mass fraction of Mg in the degradable zinc alloy is 3.0 wt.%, the mass fraction of Li is 0.1 wt.%, the mass fraction of Ag is 3.0 wt.%, and the rest is Zn;

[0063] The preparation method comprises the following steps:

[0064] (1) According to the component proportion of the zinc alloy, raw materials of Zn, Mg, Li and Ag are weighed and put into a crucible, and the crucible is put into a vacuum furnace;

[0065] (2) After the charging is completed, the smelting furnace is vacuumed and argon is flushed to ensure an argon atmosphere in the furnace, and the vacuum degree of the vacuuming is not more than 4 Pa;

[0066] (3) Heating is started, and the temperature is raised to 650 ℃ and kept for 20 min, then the alloy liquid is stirred for 10 min using a mechanical stirring rod provided in the smelting furnace, and then kept for 5 min, and a Zn-Mg-Li-Ag alloy ingot is obtained by pouring;

[0067] (4) The Zn-Mg-Li-Ag alloy ingot obtained in step (3) is subjected to rod organization regulation to obtain a zinc alloy rod, and the regulation process comprises, in sequence, homogenizing annealing, primary hot extrusion, water quenching after heat preservation, secondary hot extrusion, rotary swaging, and staged annealing, wherein the homogenizing annealing is annealing at 320 ℃ for 2 h and then furnace cooling; the primary hot extrusion is performed at a temperature of 290 ℃, an extrusion ratio of 30, and an extrusion speed of 10 mm / s; the water quenching after heat preservation is water quenching after heat preservation at 300 ℃ for 30 min, and then furnace cooling after heat preservation at 120 ℃ for 4 h; the secondary hot extrusion is performed at 210 ℃, an extrusion ratio of 15, and an extrusion speed of 2 mm / s; the rotary swaging has a diameter reduction rate of 45%; and the staged annealing comprises first-stage annealing at 240 ℃ for 15 min and second-stage annealing at 140 ℃ for 120 min, and then furnace cooling after the second-stage annealing;

[0068] (5) The zinc alloy rod obtained in step (4) is cold-drawn, and annealing is performed between passes, the annealing is performed at a temperature of 330 ℃, a zinc alloy wire with a diameter of 0.2 mm is obtained, the zinc alloy wire is sequentially subjected to sandpaper polishing, phosphate chemical treatment, and mechanical micro-roughening treatment, then the zinc alloy wire is cleaned and dried to obtain a treated zinc alloy wire, the surface of the zinc alloy wire is polished using 3000# and 5000# sandpaper in sequence, the phosphate chemical treatment is performed by placing the zinc alloy wire in a phosphate chemical solution to form a phosphate chemical layer on the surface of the zinc alloy wire, the thickness of the phosphate chemical layer is 1 μm, the phosphate chemical solution uses deionized water as a solvent and comprises, in terms of concentration, 30 g / L of phosphoric acid, 5 g / L of zinc nitrate, 15 g / L of sodium nitrate, and 0.5 g / L of sodium nitrite, the phosphate chemical treatment is performed at 60 ℃ for 3 min, and the zinc alloy wire is rinsed with deionized water and dried after the phosphate chemical treatment, and the zinc alloy wire is subjected to mechanical micro-roughening treatment after the phosphate chemical treatment, so that the surface roughness Ra of the zinc alloy wire is 2.5 μm;

[0069] (6) the zinc alloy wire treated in step (5) is sequentially subjected to: forming a Zn-phytic acid complex anchoring layer, immersing a chitosan solution and drying to form a chitosan coating layer, immersing the zinc alloy wire with the chitosan coating layer into a gentian violet solution for crosslinking to form a crosslinked chitosan layer, washing the zinc alloy wire with the crosslinked chitosan layer after the crosslinking is completed to remove unbound gentian violet residues, then immersing a polylactic acid solution containing magnesium carbonate particles and drying to form a polylactic acid / magnesium carbonate composite controlled release layer, then performing nail making and sterilization to obtain a degradable zinc alloy anastomosis nail, the forming of the Zn-phytic acid complex anchoring layer comprises immersing the treated zinc alloy wire into a 0.5 wt.% aqueous phytic acid solution for 30 min, and then taking out and drying at 60°C for 20 min, so that the thickness of the Zn-phytic acid complex anchoring layer is 1.0 μm, the mass fraction of chitosan in the chitosan solution is 1.5 wt.%, and the mass fraction of acetic acid is 0.8 wt.%, the mass fraction of gentian violet in the gentian violet solution is 0.6 wt.%, the solvent of the gentian violet solution is an ethanol aqueous solution, the volume fraction of ethanol is 20%, the thickness of the crosslinked chitosan layer obtained after crosslinking treatment is 1 μm, the washing comprises: immersing the zinc alloy wire with the crosslinked chitosan layer into an ethanol aqueous solution with an ethanol volume fraction of 50% for elution for 5 min, replacing the solution 4 times during the elution, then immersing into deionized water for rinsing for 15 min, replacing the solution 2 times during the rinsing, and then drying at 40°C for 60 min, the polylactic acid solution containing magnesium carbonate particles is formed by adding magnesium carbonate particles into a polylactic acid solution, the mass fraction of polylactic acid in the polylactic acid solution is 1 wt.%, the D50 of the magnesium carbonate particles is 3 μm, and the mass ratio of the magnesium carbonate particles to the polylactic acid solution is 2:100; the residence time of the immersing is 10 s, the pulling speed is 10 mm / s, and the immersing is performed once.

[0070] Example 3

[0071] The present embodiment provides a degradable zinc alloy anastomosis nail and a preparation method thereof, which specifically comprises:

[0072] A degradable zinc alloy anastomosis nail, the mass fraction of Mg in the degradable zinc alloy is 1.5 wt.%, the mass fraction of Li is 1.5 wt.%, the mass fraction of Ag is 1.5 wt.%, and the rest is Zn;

[0073] The preparation method comprises:

[0074] (1) according to the component ratio of the zinc alloy, Zn, Mg, Li and Ag raw materials are weighed and put into a crucible, and the crucible is put into a vacuum furnace;

[0075] (2) after the charging is completed, the smelting furnace is vacuumized and argon is flushed to ensure the argon atmosphere in the furnace, and the vacuum degree of the vacuumization is not greater than 4 Pa;

[0076] (3) start heating, temperature rise to 550℃, keep for 30 min, use the mechanical stirring rod of the smelting furnace to stir the alloy liquid for 6 min, then keep for 15 min, pour to obtain the Zn-Mg-Li-Ag alloy cast rod;

[0077] (4) carry out rod organization regulation on the Zn-Mg-Li-Ag alloy cast rod obtained in step (3) to obtain the zinc alloy rod, specifically: sequentially carry out homogenizing annealing, primary hot extrusion, heat preservation water quenching, secondary hot extrusion, swaging, and grading annealing on the Zn-Mg-Li-Ag alloy cast rod to obtain the zinc alloy rod, the homogenizing annealing is annealing at 280℃ for 4 h and furnace cooling; the temperature of the primary hot extrusion is 260℃, the extrusion ratio is 50, and the extrusion speed is 6 mm / s; the heat preservation water quenching is water quenching after keeping at 315℃ for 20 min, and then furnace cooling after keeping at 150℃ for 2.5 h; the secondary hot extrusion is carried out at 230℃, the extrusion ratio is 10, and the extrusion speed is 5 mm / s; the diameter reduction rate of the swaging is 30%; the grading annealing is: the first stage annealing is annealing at 260℃ for 10 min, the second stage annealing is annealing at 150℃ for 80 min, and then furnace cooling after the second stage annealing;

[0078] (5) carry out cold drawing on the zinc alloy rod obtained in step (4), and carry out annealing treatment between passes, the temperature of the annealing treatment is 250℃, to obtain the zinc alloy wire with a diameter of 0.3 mm, sequentially carry out sandpaper polishing, phosphate chemical treatment, and mechanical micro-roughening treatment on the zinc alloy wire, then carry out cleaning and drying on the zinc alloy wire to obtain the treated zinc alloy wire, the surface of the zinc alloy wire is polished by using 3000# and 5000# sandpaper in sequence, the phosphate chemical treatment is to place the zinc alloy wire in a phosphate chemical solution to form a phosphate chemical layer on the surface of the zinc alloy wire, the thickness of the phosphate chemical layer is 2 μm, the phosphate chemical solution takes deionized water as the solvent and includes, in terms of concentration: phosphoric acid 20 g / L, zinc nitrate 12 g / L, sodium nitrate 10 g / L, and sodium nitrite 1.0 g / L; the phosphate chemical treatment is carried out at 40℃, and the treatment time is 8 min, after the phosphate chemical treatment, the zinc alloy wire is rinsed with deionized water and dried, and the mechanical micro-roughening treatment is carried out on the zinc alloy wire after the phosphate chemical treatment, so that the surface roughness Ra of the zinc alloy wire is 1.5 μm;

[0079] (6) the zinc alloy wire treated in step (5) is sequentially subjected to: forming a Zn-phytic acid complex anchoring layer, immersing a chitosan solution and drying to form a chitosan coating layer, immersing the zinc alloy wire with the chitosan coating layer into a gentian violet solution for crosslinking to form a crosslinked chitosan layer, washing the zinc alloy wire with the crosslinked chitosan layer after the crosslinking is completed to remove unbound gentian violet residues, then immersing a polylactic acid solution containing magnesium carbonate particles and drying to form a polylactic acid / magnesium carbonate composite controlled release layer, then performing nail making and sterilization to obtain a degradable zinc alloy anastomosis nail, the forming of the Zn-phytic acid complex anchoring layer comprises immersing the treated zinc alloy wire into a 1.2 wt.% aqueous phytic acid solution for 20 min, and then drying at 60°C for 30 min after being taken out, so that the thickness of the Zn-phytic acid complex anchoring layer is 0.5 μm, the mass fraction of chitosan in the chitosan solution is 1.2 wt.%, and the mass fraction of acetic acid is 1.0 wt.%, the mass fraction of gentian violet in the gentian violet solution is 0.4 wt.%, the solvent of the gentian violet solution is an ethanol aqueous solution, the volume fraction of ethanol is 35%, the thickness of the crosslinked chitosan layer obtained after crosslinking treatment is 2.5 μm, the washing comprises: immersing the zinc alloy wire with the crosslinked chitosan layer into an ethanol aqueous solution with an ethanol volume fraction of 30% for elution for 10 min, replacing the solution 3 times during the elution, then immersing it into deionized water for rinsing for 10 min, replacing the solution 3 times during the rinsing, and then drying at 50°C for 40 min, the polylactic acid solution containing magnesium carbonate particles is formed by adding magnesium carbonate particles into a polylactic acid solution, the mass fraction of polylactic acid in the polylactic acid solution is 1.5 wt.%, the D50 of the magnesium carbonate particles is 1.5 μm, and the mass ratio of the magnesium carbonate particles to the polylactic acid solution is 1.3:100; the residence time of the immersing is 30 s, the pulling speed is 5 mm / s, and the immersing is performed twice.

[0080] Example 4

[0081] The present embodiment provides a degradable zinc alloy anastomosis nail and a preparation method thereof, which specifically comprises:

[0082] A degradable zinc alloy anastomosis nail, the mass fraction of Mg in the degradable zinc alloy is 2.0 wt.%, the mass fraction of Li is 0.5 wt.%, the mass fraction of Ag is 1.0 wt.%, and the rest is Zn;

[0083] The preparation method thereof comprises:

[0084] (1) according to the component ratio of the zinc alloy, the raw materials of Zn, Mg, Li and Ag are weighed and put into a crucible, and the crucible is put into a vacuum furnace;

[0085] (2) after the charging is completed, the smelting furnace is vacuumized and argon is flushed to ensure the argon atmosphere in the furnace, and the vacuum degree of the vacuumization is not greater than 4 Pa;

[0086] (3) start heating, temperature rise to 600 ℃, keep for 25 min, use the mechanical stirring rod of the smelting furnace to stir the alloy liquid for 8 min, then keep for 20 min, pour to get Zn-Mg-Li-Ag alloy cast bar;

[0087] (4) carry out bar organization regulation to the Zn-Mg-Li-Ag alloy cast bar obtained in step (3) to obtain zinc alloy bar, specifically: sequentially carry out homogenizing annealing, primary hot extrusion, heat preservation water quenching, secondary hot extrusion, swaging, and grading annealing to the Zn-Mg-Li-Ag alloy cast bar to obtain the zinc alloy bar, the homogenizing annealing is annealing at 300 ℃ for 5 h and then furnace cooling; the temperature of the primary hot extrusion is 270 ℃, the extrusion ratio is 60, and the extrusion speed is 8 mm / s; the heat preservation water quenching is water quenching after keeping at 320 ℃ for 25 min, and then furnace cooling after keeping at 160 ℃ for 3 h; the secondary hot extrusion is carried out at 240 ℃, the extrusion ratio is 12, and the extrusion speed is 6 mm / s; the diameter reduction rate of the swaging is 40%; the grading annealing is: the first stage annealing is annealing at 270 ℃ for 12 min, the second stage annealing is annealing at 160 ℃ for 100 min, and then furnace cooling after the second stage annealing is completed;

[0088] (5) carry out cold drawing to the zinc alloy bar obtained in step (4), carry out annealing treatment between passes, the temperature of the annealing treatment is 280 ℃, to obtain zinc alloy wire with a diameter of 0.25 mm, sequentially carry out sandpaper polishing, phosphate chemical treatment, and mechanical micro-roughening treatment to the zinc alloy wire, then carry out cleaning and drying to the zinc alloy wire to obtain treated zinc alloy wire, the surface of the zinc alloy wire is polished by sequentially using 3000# and 5000# sandpaper, the phosphate chemical treatment is to place the zinc alloy wire in a phosphate chemical solution to form a phosphate chemical layer on the surface of the zinc alloy wire, the thickness of the phosphate chemical layer is 2.5 μm, the phosphate chemical solution takes deionized water as solvent and includes, by concentration: phosphoric acid 25 g / L, zinc nitrate 15 g / L, sodium nitrate 8 g / L, and sodium nitrite 1.5 g / L; the phosphate chemical treatment is carried out at 50 ℃, and the treatment time is 5 min, after the phosphate chemical treatment, the zinc alloy wire is rinsed with deionized water and dried, the mechanical micro-roughening treatment is carried out to the zinc alloy wire after the phosphate chemical treatment, so that the surface roughness Ra of the zinc alloy wire is 2.0 μm;

[0089] (6) the zinc alloy wire after step (5) is sequentially subjected to: forming a Zn-phytic acid complex anchoring layer, immersing a chitosan solution and drying to form a chitosan coating layer, immersing the zinc alloy wire with the chitosan coating layer into a gentian violet solution for cross-linking to form a cross-linked chitosan layer, after the cross-linking is completed, eluting and cleaning the zinc alloy wire with the cross-linked chitosan layer to remove unbound gentian violet residues, then immersing a polylactic acid solution containing magnesium carbonate particles and drying to form a polylactic acid / magnesium carbonate composite controlled release layer, then performing nail making and sterilization to obtain a degradable zinc alloy anastomosis nail, the forming of the Zn-phytic acid complex anchoring layer comprises immersing the treated zinc alloy wire into a 1.5 wt.% aqueous phytic acid solution for 25 min, and after being taken out, drying at 60°C for 25 min, so that the thickness of the Zn-phytic acid complex anchoring layer is 0.8 μm, the mass fraction of chitosan in the chitosan solution is 1.0 wt.%, and the mass fraction of acetic acid is 0.9 wt.%, the mass fraction of gentian violet in the gentian violet solution is 0.5 wt.%, the solvent of the gentian violet solution is an ethanol aqueous solution, the volume fraction of ethanol is 40%, the thickness of the cross-linked chitosan layer obtained after cross-linking treatment is 3 μm, the eluting and cleaning comprises: placing the zinc alloy wire with the cross-linked chitosan layer into an ethanol aqueous solution with an ethanol volume fraction of 40% for elution for 8 min, changing the solution 3 times during the elution, then placing it into deionized water for rinsing for 8 min, changing the solution 4 times during the rinsing, then drying at 55°C for 50 min, the polylactic acid solution containing magnesium carbonate particles is formed by adding magnesium carbonate particles into a polylactic acid solution, the mass fraction of polylactic acid in the polylactic acid solution is 1.8 wt.%, the D50 of the magnesium carbonate particles is 2 μm, and the mass ratio of the magnesium carbonate particles to the polylactic acid solution is 1.7:100; the residence time of the immersing is 40 s, the pulling speed is 8 mm / s, and the immersing is performed twice.

[0090] Comparative Example 1

[0091] The present comparative example provides a degradable zinc alloy anastomosis nail and a preparation method thereof, which is different from Example 1 in that step (6) does not perform phytic acid treatment when the functional layer is constructed, and other process parameters and operating conditions are completely the same as those of Example 1.

[0092] Comparative Example 2

[0093] The present comparative example provides a degradable zinc alloy anastomosis nail and a preparation method thereof, which is different from Example 1 in that after the chitosan coating layer is dried to form a film, the zinc alloy wire is not subjected to gentian violet solution cross-linking treatment, and then a polylactic acid / magnesium carbonate composite layer is directly immersed, and other process parameters and operating conditions are completely the same as those of Example 1.

[0094] Comparative Example 3

[0095] The comparative example provides a degradable zinc alloy anastomat and a preparation method thereof, which is different from example 1 in that no magnesium carbonate particles are added to the outer layer polylactic acid solution in step (6), and other process parameters and operating conditions are completely the same as those in example 1.

[0096] Comparative example 4

[0097] The comparative example provides a degradable zinc alloy anastomat and a preparation method thereof, which is different from example 1 in that only sandpaper polishing and mechanical micro-roughening are performed for surface pretreatment in step (5) to achieve the same roughness requirement, and no phosphating treatment is performed, and other process parameters and operating conditions are completely the same as those in example 1.

[0098] The zinc alloy wires and degradable zinc alloy anastomats prepared in the above examples 1-4 and comparative examples 1-4 are subjected to performance tests, and the specific test methods are as follows:

[0099] Mechanical properties: a universal material testing machine is used to perform a tensile test at room temperature, and the tensile rate is 5 mm / min. Considering that the coating has little effect on the mechanical properties in the present application, only the zinc alloy wires prepared in examples 1-4 are detected in the mechanical property test. The mechanical property test results are shown in table 1.

[0100] In-vitro degradation experiment: the prepared degradable zinc alloy anastomats are immersed in a SBF simulated body fluid at 37℃ for 3 days, 7 days, 14 days, 21 days and 30 days, the weight loss of the sample before and after immersion is measured to obtain the corrosion rate of the material, and the unit of the corrosion rate is mm / y. The corrosion rate of the immersed sample is calculated by the following formula, CR=(k×w) / (A×t×D), CR is the corrosion rate (mm / y), k=8.76×10 4 , w is the weight loss (g), which is M1 minus M2, M1 is the mass of the anastomat before immersion, M2 is the mass of the anastomat after immersion, A is the surface area (cm 2 ), t is the immersion time (h), and D is the sample density (g·cm -3 ). The in-vitro degradation experiment test results are shown in table 2.

[0101] Table 1 Mechanical property test results of zinc alloy wires in examples 1-4

[0102]

[0103] Table 2 In-vitro degradation experiment test results of degradable zinc alloy anastomats in examples 1-4 and comparative examples 1-4

[0104]

[0105] As shown in Table 2, the corrosion rates of Comparative Examples 1-4 are all increased compared to Example 1. This is because Comparative Example 1 has no phytic acid anchoring layer, and lacks multi-site coordination bridges between the phosphatizing layer and the chitosan layer, so water is easily introduced at the interface and under-film corrosion occurs. After the crosslinking of gentian violet is cancelled in Comparative Example 2, the chitosan layer chain segment migration and swelling are more obvious, and the pore and ion channel are more easily formed, so the chloride ions and dissolved oxygen reach the metal surface more quickly. When the outer layer does not contain magnesium carbonate particles in Comparative Example 3, the acidic products produced by the hydrolysis of polylactic acid lack buffering, and the local pH reduction promotes zinc dissolution. After the phosphatizing layer is cancelled in Comparative Example 4, the surface lacks the barrier of the inorganic conversion film and the chemical bonding sites, so the phytic acid anchoring layer and the subsequent coating are more likely to have pinholes and penetration channels, and the electrolyte reaches the metal surface more quickly and induces under-film corrosion.

[0106] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily conceived, and all such changes and replacements fall within the protection scope and disclosure scope of the present application.

Claims

1. A biodegradable zinc alloy staple, characterized in that, The zinc alloy contains 0-3.0 wt.% Mg, 0-3.0 wt.% Li, and 0-3.0 wt.% Ag by mass, with the mass fractions of Mg, Li, and Ag not being zero, and the remainder being Zn. The anastomotic staples include zinc alloy wire made from the zinc alloy, a surface pretreatment layer and a functional coating disposed on the surface of the zinc alloy wire, wherein the surface pretreatment layer includes a roughened surface formed by sandpaper polishing and a phosphate formation layer; the functional coating includes, from the inside out, a Zn-phytic acid complex anchoring layer, a cross-linked chitosan layer, and a polylactic acid / magnesium carbonate composite controlled-release layer.

2. A method for preparing a biodegradable zinc alloy staple as described in claim 1, characterized in that, The preparation method includes: Step (1) Weigh Zn, Mg, Li and Ag raw materials according to the zinc alloy composition ratio, put the weighed zinc alloy raw materials into a crucible, and put the crucible into a vacuum furnace; After the charging process is completed in step (2), the smelting furnace is evacuated and purged with argon gas to ensure an argon atmosphere inside the furnace. Step (3) Start heating, raise the temperature to the first temperature and hold it, stir the alloy liquid with the mechanical stirring rod of the melting furnace and continue to hold it, and pour to obtain Zn-Mg-Li-Ag alloy casting rod; Step (4) The Zn-Mg-Li-Ag alloy casting rod obtained in step (3) is subjected to rod microstructure regulation and zinc alloy rod is obtained. Specifically, the Zn-Mg-Li-Ag alloy casting rod is subjected to homogenization annealing, first hot extrusion, heat preservation water quenching, second hot extrusion, rotary forging and graded annealing in sequence to obtain zinc alloy rod. Step (5) The zinc alloy bar obtained in step (4) is cold drawn and annealed between passes to obtain zinc alloy wire. The zinc alloy wire is then sanded, phosphated and mechanically roughened. The zinc alloy wire is then cleaned and dried to obtain the treated zinc alloy wire. Step (6) involves the following steps on the surface of the zinc alloy wire treated in step (5): forming a Zn-phytic acid complex anchoring layer, dipping in a chitosan solution and drying it to form a chitosan coating, dipping the zinc alloy wire with the chitosan coating into a gentian violet solution for cross-linking to form a cross-linked chitosan layer, washing and cleaning the zinc alloy wire with the cross-linked chitosan layer after cross-linking to remove unbound gentian violet residue, then dipping in a polylactic acid solution containing magnesium carbonate particles and drying it to form a polylactic acid / magnesium carbonate composite controlled-release layer, then making the staple and sterilizing it to obtain a biodegradable zinc alloy staple.

3. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (4): The homogenization annealing is carried out at 260-320℃ for 2-6 hours, followed by furnace cooling. The temperature of the first hot extrusion is 230-290℃, the extrusion ratio is 30-70, and the extrusion speed is 3-10mm / s. The heat preservation and water quenching process involves holding the temperature at 300-330℃ for 10-30 minutes, followed by water quenching, and then holding the temperature at 120-170℃ for 1-4 hours before cooling in the furnace. The secondary hot extrusion is carried out at 210-250℃, with an extrusion ratio of 6-15 and an extrusion speed of 2-8 mm / s. The diameter reduction rate of the rotary forging is 20-45%; The staged annealing process is as follows: the first stage of annealing is carried out at 240-280℃ for 6-15 minutes, the second stage of annealing is carried out at 140-170℃ for 40-120 minutes, and the furnace is cooled after the second stage of annealing is completed.

4. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (5): The sandpaper polishing involves sequentially using 3000# and 5000# sandpaper to polish the surface of the zinc alloy wire.

5. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (5): The phosphate formation treatment involves placing the zinc alloy wire in a phosphate formation solution to form a phosphate formation layer on the surface of the zinc alloy wire. The thickness of the phosphate formation layer is 1-3 μm. The phosphate formation solution uses deionized water as a solvent and includes phosphoric acid, zinc nitrate, sodium nitrate, and sodium nitrite by concentration. The concentration of phosphoric acid is 10-30 g / L, the concentration of zinc nitrate is 5-20 g / L, the concentration of sodium nitrate is 5-15 g / L, and the concentration of sodium nitrite is 0.5-2.0 g / L. The phosphate formation treatment is carried out at 25-60°C for 3-12 minutes. After the phosphate formation treatment, the wire is rinsed with deionized water and dried.

6. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (5): The mechanical micro-roughening treatment reduces the surface roughness Ra of the zinc alloy wire to 0.8-2.5 μm.

7. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (6): The formation of the Zn-phytic acid complex anchoring layer involves immersing the treated zinc alloy wire in a 0.5-2.0 wt.% phytic acid aqueous solution for 10-30 min, then drying it at 60°C for 20-40 min to achieve a Zn-phytic acid complex anchoring layer thickness of 0.2-1.0 μm.

8. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (6): The chitosan solution contains 0.8-1.5 wt.% chitosan and 0.8-1.2 wt.% acetic acid.

9. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (6): The gentiocyanate solution contains 0.2-0.6 wt.% gentiocyanate by mass, and the solvent of the gentiocyanate solution is an aqueous ethanol solution, wherein the volume fraction of ethanol is 20-50%, and the thickness of the cross-linked chitosan layer obtained after cross-linking treatment is 1-4 μm. The elution and cleaning process includes: eluting the zinc alloy wire forming the cross-linked chitosan layer in an ethanol aqueous solution with a volume fraction of 20-50% for 5-15 minutes, changing the solution 2-4 times during the elution process, rinsing it in deionized water for 5-15 minutes, changing the solution 2-5 times during the rinsing process, and then drying it at 40-60°C for 20-60 minutes.

10. The method for preparing a biodegradable zinc alloy staple according to claim 2, characterized in that, In step (6): The polylactic acid solution containing magnesium carbonate particles is formed by adding magnesium carbonate particles to a polylactic acid solution. The D50 of the magnesium carbonate particles is 0.5-3 μm, and the mass ratio of the magnesium carbonate particles to the polylactic acid solution is (1-2):

100. The dip-coating residence time is 10-60s, the lifting speed is 1-10mm / s, and the number of dip-coating cycles is 1-3.

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