JP2018202074A - Medical bioabsorbable member and method for producing the same - Google Patents

Abstract

To provide a novel medical bioabsorbable member that has a coat and a base material, both of which are in vivo dissolved and absorbed to be lost completely, and a method of producing the same.SOLUTION: The present invention provides a medical bioabsorbable member in which an anticorrosive coat, which adjusts the in-vivo dissolution timing, coats the surface of a base material composed of magnesium or a magnesium alloy. The anticorrosive coat is a bioabsorbable coat comprising a WH/Mg-TCP calcium phosphate coat as the main component.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a bioabsorbable member for medical use in which the surface of a base material made of magnesium or a magnesium alloy is covered with a corrosion-resistant coating that adjusts the time of dissolution in vivo, and more specifically, various stents, miniplates, The present invention relates to a medical bioabsorbable device such as a scaffold.

  Magnesium material corrodes and disappears in solutions containing chloride ions such as body fluids, and is less harmful to magnesium, and higher in strength than biodegradable polymers such as polylactic acid Therefore, application as a bioabsorbable metal material for medical use is being studied. The bioabsorbable material is a material that retains strength to support a load applied to surrounding tissues until the affected area is healed, and dissolves and is absorbed after the affected area is healed. Therefore, in the bioabsorbable member, it is required that corrosion is suppressed over a necessary period in order to maintain a necessary strength for an arbitrary period after implantation.

  The strength retention period required for the bioabsorbable device ranges from a very long and short range depending on the type of the device and the state of the affected part. For example, in the case of a fracture fixing material, it is desired that the device supports the load for a period of 3 months to 1 year until the fracture is healed, and then the disassembly of the entire device is almost completed in a period of 8 months to 5 years. However, a magnesium material that can suppress corrosion for 3 months or more in vivo has not been developed. In addition, it is very difficult to achieve the development of a magnesium material having a desired corrosion inhibition period and strength by controlling the alloy composition and the alloy structure. Therefore, it is required to extend the period during which corrosion is suppressed in the living body by forming a corrosion-resistant film on the surface of the magnesium material having the necessary mechanical properties. Moreover, when it embeds over a long period of time, a high biocompatibility is also required for the corrosion resistant coating.

Since the apatite crystal is calcium phosphate having a relatively high thermodynamic stability in a neutral salt solution such as an in vivo environment, it is considered that the corrosion resistance of the substrate can be improved by being present in the surface coating. Further, since the apatite crystal is a bone component, it is considered that the biocompatibility of the base material can be improved.
However, since magnesium is an element that inhibits crystallization of apatite, it has been considered difficult to deposit apatite directly on the surface of the magnesium material in an aqueous solution. The inventors of the present invention have solved the above-described conventional problems, and a material in which a film mainly composed of apatite crystals is directly deposited on the surface of the magnesium material, and an aqueous solution for producing a film mainly composed of apatite crystals. And a manufacturing method has been proposed (see Patent Document 1).

However, the film disclosed in Patent Document 1 is a film mainly composed of hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , HAp). Hydroxyapatite is a component of bone and has high biocompatibility, but has been reported to remain in vivo for a relatively long period of time because it is chemically stable in the in vivo environment (see Non-Patent Document 2).
That is, when a hydroxyapatite-coated magnesium alloy produced by the production method disclosed in Patent Document 1 was implanted subcutaneously in mice for 16 weeks, the apatite film remained almost undissolved. On the other hand, if the remaining coating breaks into particles, it can induce immune system cells and cause inflammation. Therefore, in order to ensure a safe and secure biocompatibility as a medical bioabsorbable member, it is necessary to dissolve and eliminate the coating.

Non-Patent Document 1 discloses a technique in which a β-TCP film is formed on a pure Mg surface and biocompatibility is evaluated. As a pretreatment, pure Mg was immersed in a supersaturated Na ₂ HPO ₄ aqueous solution at room temperature (25 ° C.) for 3 hours and then heat treated at 400 ° C. for 10 hours. The composition of the β-TCP coating treatment solution is Na ₂ HPO ₄ · 12H ₂ O (23.75 g / L) —Ca (NO ₃ ) ₂ (18.2 g / L). Heat-treated at 70 ° C. for 48 hours.
However, Non-Patent Document 1 produces β-TCP having a stoichiometric composition that does not contain Mg. Therefore, the method of Non-Patent Document 1 has a problem that pre-processing is required and the manufacturing process becomes complicated.

Japanese Patent No. 5339347

The preparation, cytocompatibility, and in vitro biodegradation study of pure β-TCP on magnesium, J. Mater. Sci. Mater. Med., 20, 1149-1157 (2009). “Bioabsorbability and bone formation evaluation of carbon-containing apatite porous bodies with different porosity” Tokyo Medical and Dental University Biomaterials Engineering Laboratory Life Innovation Materials Creation Joint Research Project http://www.tmd.ac.jp/i- mde / www / kyoudou / labo /

  The present invention solves the above-described problems, and an object thereof is to provide a novel bioabsorbable member for medical use in which both a coating and a substrate are dissolved and absorbed in a living body and completely disappeared, and a method for producing the same.

  The medical bioabsorbable member of the present invention is a medical bioabsorbable member in which the surface of a base material made of magnesium or a magnesium alloy is covered with a corrosion-resistant coating that adjusts the dissolution time in vivo. The corrosion-resistant film is a bioabsorbable film mainly composed of an Mg-containing calcium phosphate film.

In the bioabsorbable member for medical use according to the present invention, preferably, the Mg-containing calcium phosphate coating includes, as calcium phosphate, witrokite (Ca ₉ (MgFe) (PO ₄ ) ₆ PO ₃ OH), tricalcium phosphate (Ca _3). (PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), calcium hydrogen phosphate dihydrate (CaHPO ₄ .2H ₂ O), octacalcium phosphate (Ca ₈ (PO ₄ ) ₄ (HPO ₄ ) ₂ It may be represented by at least one selected from the group consisting of (OH) ₂ ).
Here, the witrokite (Ca ₉ (MgFe) (PO ₄ ) ₆ PO ₃ OH) contains both Mg and Fe, such as witrokite collected as a mineral, and the implementation of the present invention. There are some which contain only Mg and do not contain Fe, such as WH / Mg-TCP manufactured in the example.
In the bioabsorbable member for medical use of the present invention, preferably, the corrosion-resistant film and the base material are integrated with each other via a magnesium hydroxide layer.

  A method for producing a medical bioabsorbable member of the present invention, wherein a magnesium or magnesium alloy base material molded into a predetermined shape is treated in a treatment aqueous solution in which phosphate ions and non-chlorinated calcium ions are dissolved in a supersaturated state. It is preferable that the bioabsorbable coating mainly composed of the Mg-containing calcium phosphate coating is deposited on the surface of the substrate.

In the method for producing a medical bioabsorbable member of the present invention, preferably, the calcium ions in the treatment aqueous solution are obtained by dissolving a calcium chelate compound.
In the method for producing a medical bioabsorbable member of the present invention, it is preferable that a magnesium-containing compound to which Mg ²⁺ ions are added is contained in the treatment aqueous solution.

In the method for producing a bioabsorbable member for medical use according to the present invention, preferably, Mg (OH) ₂ , Mg (NO ₃ ) ₂ , Mg ₃ (PO ₄ ) is used to add Mg ²⁺ ions to the treatment aqueous solution. ₂ , at least one selected from the group consisting of MgCO ₃ , Mg (CH ₃ COO) ₂ , magnesium citrate, magnesium malate, magnesium glutamate, magnesium stearate, Mg gluconate, Mg-EDTA, pure Mg or magnesium alloy It may have a magnesium-containing compound represented.

  In the method for producing a bioabsorbable member for medical use of the present invention, preferably, the temperature of the treatment aqueous solution is 60 ° C. or higher and 100 ° C. or lower.

According to the present invention, the coating of the present invention is known to be witrokite (WH) / Mg-substituted β-TCP (Mg), which is known to be chemically dissolved / osteoclast resorbed in vivo to replace bone. -TCP) coating and a mixed coating of WH / Mg-TCP and DCPA. It can be expected that the Mg alloy coated with these easily dissolves and disappears both in the living body and in the living body.
The WH / Mg-TCP and DCPA of the present invention have higher chemical solubility than hydroxyapatite, and it has been reported in animal experiments and clinical tests that they are replaced with living bone earlier than hydroxyapatite. Therefore, the WH / Mg-TCP coated Mg alloy is a material that dissolves and is absorbed in vivo and completely disappears.

FIG. 1 is an SEM image of a WH / Mg-TCP coated surface produced with Mg (OH) ₂ added (WH01) according to an embodiment of the present invention. FIG. 2 is an SEM image of a WH / Mg-TCP coated surface produced without adding Mg (OH) ₂ (WH02) according to an embodiment of the present invention. FIG. 3 is an XRD pattern of a sample coated with WH01 and WH02 treatment solutions. FIG. 4 is a surface SEM image of a sample coated with a 1/2 diluted solution. FIG. 5 is a surface SEM image of a sample coated with a 1/10 diluted solution. FIG. 6 is an XRD pattern of a sample coated with a high concentration solution. FIG. 7 is an XRD pattern of a sample coated with a low concentration solution. FIG. 8 is a surface SEM image of a sample coated with a processing time of 10 minutes. FIG. 9 is a surface SEM image of a sample coated with a treatment time of 40 minutes. FIG. 10 is an XRD pattern of samples coated at 90 ° C. with various processing times. FIG. 11 is a surface SEM image of a sample coated at 80 ° C. for a treatment time of 2 h. FIG. 12 is a surface SEM image of a sample coated at 80 ° C. for a treatment time of 4 h. FIG. 13 is a surface SEM image of a sample coated at 80 ° C. for a treatment time of 6 h. FIG. 14 is an XRD pattern of a sample processed at a processing temperature of 80 ° C. and changing the processing time. FIG. 15 is a cross-sectional SEM image of a sample coated at 90 ° C. for 1 h. FIG. 16 is a cross-sectional SEM image of a sample coated by treatment at 80 ° C. for 2 hours.

Explanation of Terms Whitlockite (English: Whitlockite, abbreviation: WH) is a mineral, an unusual form of calcium phosphate. The composition formula is represented by Ca ₉ (MgFe) (PO ₄ ) ₆ PO ₃ OH. This is a relatively rare mineral but is found in granitic pegmatites, phosphate rock deposits, Guano caves and chondrites.
Tricalcium phosphate (abbreviation: TCP) is a salt of phosphoric acid and calcium represented by the chemical formula: Ca ₃ (PO ₄ ) ₂ . Naturally produced as apatite, widely distributed in soil, essential for plant growth, and a substance obtained when bones are burned. Tricalcium phosphate has three polymorphs, monoclinic α- and hexagonal α'-tricalcium phosphate (α-TCP, α'-TCP) is a high temperature polymorph of tricalcium phosphate Β-tricalcium phosphate (β-TCP) is a low temperature polymorph. The crystallographic density of β-tricalcium phosphate is 3.066 gcm ⁻³ .

Calcium hydrogen phosphate is represented by the chemical formula (CaHPO ₄ ) and is abbreviated as DCPA.
Calcium hydrogen phosphate dihydrate is represented by the chemical formula (CaHPO ₄ .2H ₂ O), and is abbreviated as DCPD.
The octacalcium phosphate is represented by the chemical formula (Ca ₈ (PO ₄ ) ₄ (HPO ₄ ) ₂ (OH) ₂ ), and the abbreviation is OCP.

Stoichiometric β-TCP is a stable crystalline phase at high temperatures and is usually produced by firing. In the aqueous solution treatment at 100 ° C. or lower as in the coating conditions in the present invention, β-TCP having a stoichiometric composition is not generated. Here, when cations such as Mg are incorporated into the crystal structure, the β-TCP structure is stabilized even at 100 ° C. or lower, and becomes Mg-TCP or WH. Since WH and β-TCP are very similar in crystal structure and composition, they cannot be easily distinguished.
On the other hand, since the stoichiometric β-TCP (not containing Mg) has already been marketed as a bioabsorbable artificial bone component, the WH / Mg-TCP coating is an advantageous component for approval as a medical device. It is. Since WH and Mg-TCP have similar crystal structures and compositions, it is very difficult to separate them by XRD measurement or component analysis. However, since their chemical properties are similar, they are clear as biomaterials. There is no need to categorize.

Since the WH / β-TCP structure is relatively stable on the acidic side, the pH of the treatment solution was set to 2.7 to 4.0. The base magnesium alloy easily corrodes and dissolves in an acidic aqueous solution, the WH / β-TCP structure was obtained without adding Mg (OH) ₂ , and the base magnesium alloy corroded and dissolved by cross-sectional observation Since a boundary layer mainly composed of Mg (OH) ₂ was observed and β-TCP having a stoichiometric composition cannot be thermodynamically processed at the processing temperature in this example, the coating structure of the present invention It can be said that Mg eluted from the base material is taken in. The present invention is considered to be advantageous in that the magnesium source does not need to be added to the treatment solution in the WH / Mg-TCP coating on the magnesium alloy.

Example 1: Effect of Mg (OH) ₂ Addition to Treatment Solution on Witrokite (WH) and Mg-Substituted β-Tricalcium Phosphate (Mg-TCP) Film Formation Ca-EDTA-H ₃ shown in Table 1 After heating the PO ₄ (—Mg (OH) ₂ ) aqueous solution to 90 ° C., a Mg-4Y-3RE (WE43) alloy disk (diameter 16.8 mm × thickness 2 mm) finished with # 1200 abrasive paper is immersed. The treatment for 1 hour was performed.
1 and 2 show surface SEM images of samples treated with a treatment solution with and without the addition of Mg (OH) ₂ . All of the surfaces were covered with porous precipitates, and it was found that a film was formed.
FIG. 3 shows the XRD pattern of the sample treated with the treatment solution with and without the addition of Mg (OH) ₂ . Regardless of the addition of Mg (OH) ₂ , witrokite (WH) and / or Mg-substituted β-tricalcium phosphate (Mg-TCP) structures were obtained.
From the results of SEM observation and XRD, it was found that a WH / Mg-TCP film can be formed with this treatment solution.

In Example 1, Mg (OH) ₂ was used to add Mg ²⁺ ions, which improve β-TCP structure stability at 100 ° C. or lower, to the treatment solution. However, in this addition amount, the WH / Mg-TCP structure was used. There was no effect on the formation of. Since the solubility of Mg (OH) ₂ in water is as low as 1.2 mg / 100 cm ^3, it is difficult to dissolve a higher concentration of Mg (OH) ₂ in the treatment solution. In addition, MgCO ₃ , MgSO ₄ , MgSO ₃ , MgClO ₄ , Mg (NO ₃ ) ₂ , Mg ₃ (PO ₄ ) ₂ , MgCl ₂ , MgF _{2 and the} like are considered as Mg sources to be added to the treatment solution, but MgCO ₃ Has a low solubility in water of 0.0012 mol / L (25 ° C.), and MgF ₂ hardly dissolves in water. Since SO ₄ ions and Cl ions added together with MgSO ₄ and MgCl ₂ corrode the base magnesium alloy, they are not suitable for use in the surface treatment solution of magnesium alloy. Organic salts such as Mg (CH ₃ COO) ₂ , magnesium citrate, magnesium malate, magnesium glutamate, and magnesium stearate are also considered as sources of Mg. Moreover, complex salts, such as Mg gluconate and Mg-EDTA, pure Mg, and a magnesium alloy are also mentioned as a Mg source.

Example 2: Effect of treatment solution concentration on Witrokite (WH) and Mg-substituted β-tricalcium phosphate (Mg-TCP) coatings Various concentrations of Ca-EDTA-H ₃ PO ₄ (- After heating the Mg (OH) ₂ ) aqueous solution to 90 ° C., an Mg-4Y-3RE (WE43) alloy disk (diameter 16.8 mm × thickness 2 mm) finished with # 1200 abrasive paper was immersed for 1 hour. Processed. The treatment solutions in Table 2 are concentrated two times or diluted 1/2, 1/3, 1/5 and 1/10 times based on the treatment solution of the WH02 sample.

FIG. 4 and FIG. 5 show surface SEM images of samples treated with treatment solutions of different concentrations. A porous coating was clearly observed in the 1/2 diluted solution. The formation of a film was also confirmed in the 1/10 diluted solution, and the density of the pores decreased.
6 and 7 show XRD patterns of samples treated with high and low concentration treatment solutions. The double concentration treatment solution resulted in a dicalcium phosphate anhydrous (DCPA) structure. In the sample treated with the 1/2 to 1/10 diluted solution, an XRD peak derived from the WH / Mg-TCP structure was obtained. As the concentration decreased, the XRD peak intensity decreased.
From these results, it was found that the amount of WH / Mg-TCP coating produced can be changed by the concentration of the treatment solution.

In Example 2, when the treatment solution concentration was increased, DCPA was formed instead of WH / Mg-TCP. When the treatment solution concentration is increased, the base magnesium alloy is corroded by EDTA in the treatment solution, so the Mg ²⁺ ion concentration on the alloy surface becomes too high to maintain the WH / β-TCP structure, and DCPA It is thought that it became. This suggested that there was an appropriate range for the treatment solution concentration.
On the other hand, it was found that a film having a WH / β-TCP structure can be obtained even when the treatment solution concentration is lowered. Since the XRD peak intensity decreased as the concentration decreased, it was found that the coating thickness could be changed by controlling the treatment solution concentration. Since the thickness of the coating affects the corrosion resistance and the adhesion to the substrate, it is considered that the thickness can be changed depending on the treatment solution concentration.

Example 3: Effect of treatment time on witlokite (WH) and Mg-substituted β-tricalcium phosphate (Mg-TCP) coating As shown in Table 3, using the same treatment solution as WH02, the treatment time was 10 The surface treatment of the WE43 alloy disk was performed by changing the time from 40 minutes to 40 minutes. As shown in FIGS. 8 and 9, the entire surface was covered with porous precipitates even after a treatment time of 10 minutes, and a film was formed. A denser film could be obtained at a treatment time of 40 minutes than when 60 minutes.

From the XRD pattern shown in FIG. 10, it was found that a film having a WH / Mg-TCP structure can be obtained even in a processing time as short as 10 minutes. As the treatment time increased, the peak intensity of WH / Mg-TCP increased.
From the above results, it was found that the thickness of the film can be changed by the treatment time.

  In Example 3, the density of the coating film was changed by changing the treatment time. While the denseness of the coating affects the corrosion resistance, the porous coating has the following advantages. When the coating is considered as a drug carrier, the porous substance is easier to carry the drug, and the drug release rate can be changed by controlling the density and size of the pores. Moreover, when compounding with a polymer etc., the mechanical occlusion of a polymer layer and a WH / Mg-TCP layer is strengthened because a polymer enters into the hole of a film.

Example 4: Effect of temperature on Witrokite (WH) and Mg-substituted β-tricalcium phosphate (Mg-TCP) coating From the WH / Mg-TCP coating prepared at 90 ° C. in Examples 1-3 In order to produce a dense film, the surface treatment was performed at a treatment temperature of 80 ° C. The composition of the treatment solution is shown in Table 4.

11 to 13 show surface SEM images of samples treated at 80 ° C. for treatment times 2 h, 4 h and 6 h. FIG. 14 shows the XRD pattern.
The surface morphology of the sample treated at 80 ° C. for 2 h in FIG. 11 was the same as the surface morphology of the sample treated at 90 ° C. for 1 h shown in FIG. The intensity of the peak attributed to WH / Mg-TCP in the XRD pattern of the 2h-treated sample shown in FIG. 14 was almost the same as the WH / Mg-TCP peak intensity in the 1h-treated sample at 90 ° C. shown in FIG. From these results, it was found that the reaction rate of WH / Mg-TCP film formation can be reduced by lowering the treatment temperature.

  The surface morphology changed at the treatment times of 2 hours and 4 hours or more at 80 ° C., and the granular deposits that were hardly seen until the treatment for 2 hours were increased at 4 hours or more. In the treatment time of 4 h, a DCPA peak appeared in addition to the WH / Mg-TCP XRD peak, and the peak intensity derived from DCPA increased as the treatment time increased. Thus, the granular deposit is considered to be DCPA. From this, it was found that a film in which WH / Mg-TCP and DCPA were mixed can be formed by increasing the treatment time. Here, DCPA is used as a bioactive bone paste. It is expected that the dissolution rate of the coating in vivo can be changed by the mixing ratio of WH / Mg-TCP and DCPA.

  15 and 16 show cross-sectional SEM images of samples coated with 90 ° C.-1 h treatment and 80 ° C.-6 h treatment, respectively. In the sample prepared at 90 ° C., a 10 μm thick magnesium hydroxide layer is formed at the boundary between the WH / Mg-TCP coating and the base Mg alloy, and it is applied to both the WH / Mg-TCP coating and the magnesium hydroxide layer. There was a crack. Some cracks in the WH / Mg-TCP coating penetrated from the surface to the intermediate layer. On the other hand, the thickness of the magnesium hydroxide layer was the same as that of the 90 ° C-1h treatment in the sample prepared at 80 ° C even though the treatment time was very long as 6h, and the surface of the WH / Mg-TCP coating No material penetrating from the base material side to the base material side. From these results, it was suggested that the density of the WH / Mg-TCP film can be improved by lowering the treatment temperature.

  In Example 4, it was found that the density of the coating could be changed by changing the treatment temperature. In the research so far, it has been found that in the preparation of a calcium phosphate-based film using Ca-EDTA, the film is formed when the treatment solution is set to 60 ° C. or higher. Therefore, the denseness of the film can also be controlled by controlling the treatment temperature in a temperature range of 60 ° C. or higher.

In the above embodiment, a medical bioabsorbable member using a WH / Mg-TCP coated Mg alloy as an object is used, but the present invention is not limited to this, and Mg The calcium phosphate coating film contains, as calcium phosphate, witrokite (Ca ₉ (MgFe) (PO ₄ ) ₆ PO ₃ OH), tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), It is represented by at least one selected from the group consisting of calcium hydrogen phosphate dihydrate (CaHPO ₄ .2H ₂ O) and octacalcium phosphate (Ca ₈ (PO ₄ ) ₄ (HPO ₄ ) ₂ (OH) ₂ ). Just do it.

According to the medical bioabsorbable member of the present invention, since the WH / Mg-TCP coated Mg alloy is used, a bone fixing material and artificial bone that can be completely dissolved and absorbed in a living body can be obtained.

Claims (8)

  A medical bioabsorbable member in which the surface of a base material made of magnesium or a magnesium alloy is covered with a corrosion-resistant coating that adjusts the dissolution time in a living body, wherein the corrosion-resistant coating is composed mainly of a Mg-containing calcium phosphate coating. A bioabsorbable member for medical use, which is a bioabsorbable coating. The medical bioabsorbable member according to claim 1, wherein the Mg-containing calcium phosphate coating includes, as calcium phosphate, witrokite (Ca ₉ (MgFe) (PO ₄ ) ₆ PO ₃ OH), tricalcium phosphate (Ca _3). (PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), calcium hydrogen phosphate dihydrate (CaHPO ₄ .2H ₂ O), octacalcium phosphate (Ca ₈ (PO ₄ ) ₄ (HPO ₄ ) ₂ A medical bioabsorbable member represented by at least one selected from the group consisting of (OH) ₂ ).   The medical bioabsorbable member according to claim 1 or 2, wherein the corrosion-resistant coating and the base material are integrated via a magnesium hydroxide layer.   It is a manufacturing method of the medical bioabsorbable member of any one of Claims 1 thru | or 3, Comprising: Phosphate ion and non-chlorinated calcium ion are used for the magnesium or magnesium alloy base material shape | molded by the predetermined shape. Production of a bioabsorbable member for medical use characterized in that the bioabsorbable coating composed mainly of an Mg-containing calcium phosphate coating is deposited on the surface of the base material by dipping in a treatment aqueous solution dissolved in a supersaturated state. Method.   5. The method for producing a medical bioabsorbable member according to claim 4, wherein the calcium ion in the aqueous treatment solution is obtained by dissolving a calcium chelate compound. . 5. The method for producing a medical bioabsorbable member according to claim 4, wherein Mg2 ⁺ ions are added to the treated aqueous solution to contain a magnesium-containing compound. The method of manufacturing a medical bioabsorbable member according to claim 6, in the processing solution for the addition of ^{Mg 2+} _{ions, Mg (OH) 2, Mg} (NO 3) 2, Mg 3 (PO 4) ₂ , at least one selected from the group consisting of MgCO ₃ , Mg (CH ₃ COO) ₂ , magnesium citrate, magnesium malate, magnesium glutamate, magnesium stearate, Mg gluconate, Mg-EDTA, pure Mg or magnesium alloy A medical bioabsorbable member comprising the magnesium-containing compound represented. The medical bioabsorbable member according to any one of claims 4 to 7, wherein the temperature of the treatment aqueous solution is 60 ° C or higher and 100 ° C or lower. .