WO2009054609A1

WO2009054609A1 - Bone regeneration membrane and method for manufacturing bone regeneration membrane

Info

Publication number: WO2009054609A1
Application number: PCT/KR2008/004932
Authority: WO
Inventors: Chang Kook You; Kwang Bum Park; Kyoung Ho Ryoo; Seok Kyu Choi; Dong Jun Yang; Hyun Wook An; Keun Oh Park
Original assignee: Megagen Implant Co., Ltd.
Priority date: 2007-10-26
Filing date: 2008-08-22
Publication date: 2009-04-30
Also published as: KR100946268B1; KR20090042529A

Abstract

Provided is a bone regeneration membrane and a method of manufacturing the same. The bone regeneration membrane includes: an outer layer having a porous semi-permeable structure and including a pharmaceutical biodegradable polymer and an amphiphilic polymer having a hydrophilic group and a hydrophobic group; and an inner layer having a fiber radial mesh structure and including a mixture of a pharmaceutical biodegradable polymer and a calcium phosphate, wherein the inner layer is formed on the outer layer.

Description

BONE REGENERATION MEMBRANE AND METHOD FOR MANUFACTURING BONE

REGENERATION MEMBRANE

[Technical Field] The present invention relates to a bone regeneration membrane including: an outer layer having a porous semi-permeable structure; and an inner layer having a fiber radial mesh structure, wherein the inner layer is formed on the outer layer, and a method of manufacturing the same. [Background Art] Recently, many trials to derive generation of new alveolar bones by enhancing recovery, deriving complete recovery of periodontal tissues, and improving bone graft results are being performed by introducing artificial membranes to damaged periodontal tissues in order to remedy alveolar bones damaged by periodontal diseases.

As one of these trials, a shielding film formed of a non-biodegradable or biodegradable material is used for a derivation tissue regeneration technique or as a dressing material for skin or mucous tissue.

Examples of the non-biodegradable material include expanded-polytetrafloroethylene (e-PTFE), ethyl cellulose (EC), high density polytetrafloroethylene (PTFE), freeze-dried dura mater (FDDMA), and titanium mesh. For shielding films formed of such non-biodegradable materials, after sufficient bone regeneration occurs, a second surgery is needed to remove them by opening a gingival. Accordingly, an inflammation reaction may occur during a bone regeneration period and the second surgery may be considered as a big burden by patients.

Examples of the biodegradable material include polylactic acid (PLA), collagens (collagen type I, III), polyglatin, polylactic-co-glycolic acid (PLGA), polyglycolic acid (PGA), lactide, and poly-L-lactic acid (PLLA)-polysiloxane-calcium carbonate.

For shielding films formed of such biodegradable materials, these shielding films are absorbed into body and removed and thus, a second surgery is not needed. However, in most cases, these shielding films have a single layer structure and a relatively large pore size of microns. Accordingly, inflow of fibroblasts is incompletely prevented and thus, a portion of a gingiva tissue grows between filled synthesis bones.

In addition, since most biodegradable polymer materials have poor attachment properties and affinity with respect to osteoblast, compared to calcium phosphate-based materials, bone regeneration is limited.

The size of the fibroblast is about 5 to 15 μm- Accordingly, to completely prevent inflow of the fibroblast, the pore size should be smaller than this size range. For example, the pore size should be in nanometer levels. In addition, a pore structure that suppresses attachment of the fibroblast or amplification of a fibroblast when attached is needed. However, currently available techniques are inappropriate to realize these functions and sufficient porosity to smoothly pass blood, body fluids, and oxygen.

In a structural aspect, most biodegradable polymer materials have a mesh structure or a porous structure formed by tangled fibers. In this case, although pore connectivity is excellent, the pore size is about 10 to 100 μm and thus, the inflow of the fibroblast cannot be prevented. In addition, since besides osteoblast, fibroblast is also easily attached, it is difficult to effectively block the gingiva tissue. [Disclosure] [Technical Problem]

The present invention provides a bone regeneration membrane and a method of manufacturing the same. The bone regeneration membrane prevents an inflow of a gingiva tissue or fibroblast that is an origin of the gingiva tissue so that growth of the gingiva tissue during a bone regeneration period following coverage with a synthesis bone filler is suppressed and a sufficiently stable bone regeneration obtained by growing a bio alveolar bone between filled synthesis bone powder is derived, when teeth are extracted for the purpose of implants or remedying of riodontal diseases and then an empty space is filled with a pharmaceutical synthesis bone power to regenerate bones. [Advantageous Effects]

A bone regeneration membrane according to the present invention is, unlike a conventional semi-permeable membrane having a single layer structure and a very large pore size, a semi-permeable membrane having a double-layer asymmetric structure in which outer and inner layers have different pore sizes. The outer layer of the bone regeneration membrane has a dense pore structure in which fine pores are regularly arranged and thus, allows blood, body fluids, and oxygen to easily pass therethrough and effectively prevent an inflow of the fibroblast that is an origin of gingiva tissue.

In addition, since the inner layer of the bone regeneration membrane has a fiber radial structure, osteoblast can be more easily attached to the inner layer due to a large specific surface area and mixing with calcium phosphate. Accordingly, for dental fields, during a bone generation period following coverage with an artificial bone, stable bone regeneration can be derived.

Furthermore, for the inner layer of the bone regeneration membrane, mixing with calcium phosphate contributes to maintenance of bioactivity, and use of a pharmaceutical biodegradable polymer relieves patients from a second surgery because the pharmaceutical biodegradable polymer is gradually absorbed into body and removed after a sufficient bone regeneration period. Accordingly, a high quality dental clinic service can be provided.

[Description of Drawings]

FIG. 1 shows images of an outer layer (a) and inner layer (b) of a bone regeneration membrane according to the present invention;

FIG. 2 shows enlarged images (x 6,000) of an outer layer of an bone regeneration membrane to explain a change in a pore size of a surface of the outer layer with respect to a supply rate of vapor when the outer layer is prepared by self-assembly;

FIG. 3 shows X-ray diffraction analysis results of a calcium phosphate-based synthesis solution, wherein the calcium phosphate-based synthesis solution is to be mixed with a pharmaceutical polymer to form an inner layer having a fiber radial structure of a bone regeneration membrane by electrospinning;

FIG. 4 shows enlarged surface images (x 3,000) of an outer layer of a bone regeneration membrane formed by electrospinning, when polycaprolactone that is a pharmaceutical polymer is used alone and when a mixture including polycaprolactone and biphasic calcium phosphate (BCP) in a ratio of 25:75 is used, respectively; and

FIG. 5 shows enlarged images (x750) illustrating attachment characteristics of a bone regeneration membrane according to the present invention when osteoblast is incubated in the bone regeneration membrane. [Best Mode]

The present invention provides a bone regeneration membrane including: an outer layer having a porous semi-permeable structure and including a pharmaceutical biodegradable polymer and an amphiphilic polymer including a hydrophilic group and a hydrophobic group; and an inner layer having a fiber radial mesh structure and including a mixture of a pharmaceutical biodegradable polymer and a calcium phosphate, wherein the inner layer is formed on the outer layer.

The present invention also provides a method of manufacturing a bone regeneration membrane, wherein the method includes: adding an amphiphilic polymer having a hydrophilic group and a hydrophobic group to a first pharmaceutical biodegradable polymer to prepare a mixture and stirring the mixture to prepare a solution; coating the solution on a substrate to form a film; adsorbing vapor particles to the film; polymerizing the film to which vapor particles are adsorbed in order to evaporate vapor particles, thereby forming an outer layer having a porous semi-permeable structure; preparing a calcium phosphate solution; mixing the calcium phosphate solution and a second pharmaceutical biodegradable polymer; and forming an inner layer having a fiber radial mesh structure on the outer layer having the porous semi-permeable structure by using the mixture of the calcium phosphate solution and the second pharmaceutical biodegradable polymer. [Mode for Invention]

A bone regeneration membrane according to the present invention includes: an outer layer having a porous semi-permeable structure including a pharmaceutical biodegradable polymer and an amphiphilic polymer including a hydrophilic group and a hydrophobic group; and an inner layer having a fiber radial mesh structure including a mixture of a pharmaceutical biodegradable polymer and a calcium phosphate, wherein the inner layer is formed on the outer layer.

The pharmaceutical biodegradable polymer used to form the outer layer may include at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

The amphiphilic polymer may, have a block copolymerization structure including polystyrene as a basic framework. That is, various block copolymers may be formed by anionic block copolymerization based on polystyrene as the basic framework.

In this case, the amphiphilic polymer may be a compound having a chemical structure in which the ratio of polystyrene to a block polymer is in a range of 2:1 to 5:1.

For example, the amphiphilic polymer may be a compound represented by Formula 1 :

(Formula 1)

where M represents a block polymer and may include at least one compound selected from the group consisting of 4-vinylpyridine, butadiene, polybutadiene, methacrylic acid, dodecylacrylamide, ω-carboxyhexylacrylamide, polyparapheylene, polythiophene, poly-3-hexylthiophene, polymethylmethacrylate, polyethylene oxide, polyvinylidene fluoride, polyacrylamide, and poly-N,N dimethylacrylamide, and the ratio of n:m may be in a range of 2:1 to 5:1. The outer layer having the porous semi-permeable structure may be formed by self-assembly. According to the self-assembly, a mixture of the pharmaceutical biodegradable polymer and the amphiphilic polymer is spin-coated to form a film and then the film is placed in a humidity chamber. In the humidity chamber, fine vapor particles are uniformly adsorbed to the film and arranged. Then, the resultant film is polymerized and dried. When the outer layer having the porous semi-permeable structure is manufactured by self-assembly, an outer layer having a regularly arranged pore structure can be obtained. However, the outer layer may also be formed using other methods. The outer layer having the porous semi-permeable structure may have a pore size in a range of 200 nm to 50 /mi.

The pharmaceutical biodegradable polymer used to form the inner layer may include at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

In the mixture of a pharmaceutical biodegradable polymer and a calcium phosphate, calcium phosphate may be added in a form of a solution prepared by using a zol-gel method.

The solution prepared by using the zol-gel method may be a biodegradable calcium phosphate-based solution selected from hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP). The inner layer may be formed by electrospinning.

In an embodiment, to realize a stable decomposition, the biodegradable calcium phosphate-based solution may be electrospun to form the inner layer. As described above, since the outer layer of the bone regeneration membrane according to the present invention has the porous semi-permeable structure having a dense porous structure and includes the pharmaceutical biodegradable polymer and the amphiphilic polymer including the hydrophilic group and the hydrophobic group, when, in dental fields, the outer layer is inserted into a gingiva tissue subcutis after coverage with a bone regenerating material, the outer layer may allow body fluid, and oxygen to easily pass through and effectively prevent an inflow and attachment of fibroblast that is an origin of a gingiva tissue.

Also, since the inner layer of the bone regeneration membrane according to the present invention has the fiber radial mesh structure and includes the mixture of the pharmaceutical biodegradable polymer and the calcium phosphate, an attachment capability of osteoblast that is an origin of a bone tissue is significantly improved due to a large specific surface area and mixing with calcium phosphate, and thus, an inflow of the gingiva tissue into a bone tissue is prevented, and, in dental fields, stable bone regeneration may be derived during a bone regeneration period after coverage with an artificial bone.

Meanwhile, a method of manufacturing a bone regeneration membrane includes: a) adding an amphiphilic polymer including a hydrophilic group and a hydrophobic group to a pharmaceutical biodegradable polymer to prepare a mixture and stirring the mixture to prepare a solution; b) coating the solution prepared in step a) on a substrate to form a film; c) adsorbing vapor particles to the film prepared in step b); d) polymerizing the film to which vapor particles are attached in step c) in order to evaporate vapor particles, thereby forming an outer layer having a porous semi-permeable structure; e) preparing a calcium phosphate solution; f) mixing the calcium phosphate solution prepared in step e) and a pharmaceutical biodegradable polymer; and g) forming an inner layer having a fiber radial mesh structure on the outer layer having the porous semi-permeable structure by using the mixture prepared in step f).

The pharmaceutical biodegradable polymer in step a) may include at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

The amphiphilic polymer in step a) may have a block copolymerization structure including polystyrene as a basic framework. That is, various block copolymers may be formed by anionic block copolymerization based on polystyrene as the basic framework.

For example, the amphiphilic polymer in step a) may be a compound represented by Formula 1:

(Formula 1)

where M represents a block polymer and may include at least one compound selected from the group consisting of 4-vinylpyridine, butadiene, polybutadiene, methacrylic acid, dodecylacrylamide, ω-carboxyhexylacrylamide, polyparapheylene, polythiophene, poly-3-hexylthiophene, polymethylmethacrylate, polyethylene oxide, polyvinylidene fluoride, polyacrylamide, and poly-N,N dimethylacrylamide, and the ratio of n:m may be in a range of 2:1 to 5:1.

In step a), the amount of the amphiphilic polymer may be in a range of 1 to 30 parts by weight based on the pharmaceutical biodegradable polymer. The mixture of the amphiphilic polymer and the pharmaceutical biodegradable polymer may be dissolved at a concentration of 1 to 10 mg per 1 ml_ with respect to a solvent and stirred. In this regard, the solvent may be chloroform, but is not limited thereto.

The amphiphilic polymer may be added in an amount of 1 to 30 weight% based on the pharmaceutical biodegradable polymer, and may be dissolved in an amount of 1 to 15 weight% in a mixed solution including 70 to 100 weight% of chloroform and 0 to 30 weight% of methanol.

In addition, in step d), when photopolymerization using ultra-violet (UV) rays is performed, 0.1 to 1 weight% of a photo initiator may be added to the mixture of the amphiphilic polymer and the pharmaceutical biodegradable polymer prepared in step a), In step b), the film may be formed by spin-coating.

Specifically, in step b), the solution including the pharmaceutical biodegradable polymer and the amphiphilic polymer prepared in step a) is dropped in an amount of 1 to 7 ml to a glass plate having a diameter of 2 to 10 cm and then, the spin-coating is performed at a rotation rate of 100 to 4000 rpm to form the film. In step c), the film prepared in step b) is placed into a chamber having humidity of

20 to 90% so that vapor particles are attached to the film.

Specifically, in step c), the film prepared in step b) is placed into a chamber having humidity of 20 to 90% and then, left to sit for 5 seconds to 30 minutes while vapor is supplied at a supply rate of 0.2 to 1.0 L/min. In step d), the film prepared in step c) may be subjected to thermal polymerization or photopolymerization. For the photopolymerization, ultra-violet (UV) rays may be irradiated to perform the photopolymerization.

The outer layer having the porous semi-permeable structure may have a pore size in a range of 200 nm to 50 μm. In step e), the calcium phosphate solution may be prepared by using a zol-gel method. The calcium phosphate solution prepared by using the zol-gel method in step e) may be a biodegradable calcium phosphate-based solution selected from hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP).

Step e) will now be described in detail. When the calcium phosphate solution is prepared by using the zol-gel method, a mole ratio of Ca/P may be controlled to be in a range of 0.5 to 2.0. Each of a Ca starting material and a P starting material is dissolved in methanol having an amount 10 mole times greater than that of the corresponding starting material. For the P starting material such as P(OC₂Hs)₃, distilled water having an amount 5 mole times greater than that of P(OC₂H₅)₃ may be further added to the resultant P starting material solution to perform a hydrolysis reaction. Then, the prepared Ca and P starting materials are reacted together and stirred and then, the reaction product is left to sit for 1 to 3 days at a temperature of 35 ^°C for aging, thereby forming the calcium phosphate solution.

In this regard, the Ca starting material may include at least one material selected from the group consisting of Ca(Nθ₃)₂4H₂θ and Ca(OC₂H₅)2, and the P starting material may include at least one material selected from the group consisting of P(OC₂Hs)₃, P(OCH₃)₃, OP(OC₂Hs)₃, and OP(OCH₃)₃.

That is, a Ca starting material including at least one material selected from the group consisting of Ca(NO₃)₂4H₂O and Ca(OC₂Hs)₂ is prepared, and a P starting material including at least one material selected from the group consisting of P(OC₂Hs)₃,

P(OCH₃)₃, OP(OC₂Hs)₃, and OP(OCH₃)₃ is prepared. For the P starting material, distilled water having an amount 3 to 10 mole times greater than the P starting material is further added to the P starting material to perform a hydrolysis reaction for 10 minutes to 5 hours. Then, the hydrolyzed P starting material is reacted with the Ca starting material to form the calcium phosphate solution.

For example, in step e), the calcium phosphate solution can be prepared by using a zol-gel method in which Ca(NO₃)₂4H₂O is reacted with P(OC₂Hs)₃ and then the reaction product is aged. In this case, a BCP calcium phosphate solution can be manufactured The pharmaceutical biodegradable polymer in step f) may include at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

In step f), the calcium phosphate solution prepared in step e) may be mixed with the pharmaceutical biodegradable polymer in a ratio of 10:90 to 90:10. In this regard, the pharmaceutical biodegradable polymer may be dissolved in a mixed solution including 70 to100 weight% of chloroform and 0 to 30 weight% of methanol and the amount of the pharmaceutical biodegradable polymer may be in a range of 1 to 15 weight% based on the mixed solution.

In this case, in step f), the solution prepared by dissolving the pharmaceutical biodegradable polymer in the mixed solution is mixed with the calcium phosphate solution prepared in step e) in a ratio of 10:90 to 90:10, thereby producing a solution for electrospinning in step g) to be described later.

In step g), the inner layer having the fiber radial mesh structure is formed by electrospinning. Specifically, in step g), the electrospinning is performed by applying a voltage in a range of 10 to 30 kV for 1 to 60 minutes while the mixed solution prepared in step f) is supplied at a supply rate in a range of 0.5 to 3 ml/h.

For example, for the electrospinning, the outer layer prepared in step d) is placed on a bottom plane electrode, and a distance between a nozzle and the bottom plane electrode is maintained to be in a range of 10 to 30 cm. Then, the electrospinning is performed at a voltage of 10 to 30 KV for 1 to 30 minutes, and then drying is performed at a temperature of 60 to 200 ^°C for 10 to 30 minutes.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 5. FIG. 1 shows images of a bone regeneration membrane according to the present invention. Referring to FIG. 1, the bone regeneration membrane according to the present invention includes an outer layer (a) having regularly arranged pores formed by self-assembly and an inner layer (b) having a fiber radial structure formed by electrospinning.

The outer layer is exposed toward a gingiva in an oral structure, and the inner layer is exposed toward an alveolar bone covered with a synthesis bone.

FIG. 2 are images showing the adsorption behavior of vapor particles and a pore size, according to the flow rate of vapor in a chamber having 80% of humidity, when the outer layer having the porous semi-permeable is formed.

When no vapor is provided, the formed film has no pores and a dense structure. However, when a vapor is provided at a supply rate of 0.2 L/min, a uniform pore structure having a pore size of about 500 nm can be obtained. As the supply rate is increased, the pore size is increased. However, when the vapor is supplied at a supply rate of 1.0 L/min or more, adsorbed vapor particles are combined to form a larger vapor particle and the independent regular pore arrangement structure is thus collapsed.

FIG. 3 shows X-ray diffraction analysis results of hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP), which are prepared by using the zol-gel method.

For HA, the mole ratio of Ca/P is controlled to be in a range of 1.6 to 1.7; for β-TCP, the mole ratio of Ca/P is controlled to be in a range of 1.4 to1.6; and for BCP, the mole ratio of Ca/P is controlled to be in a range of 1.5 to 1.6. To be used to form a biodegradable bone regeneration membrane, β-TCP and BCP that are well known as a biodegradable calcium phosphate-based material can be chosen. For example, to realize stable decomposition, BCP is used for the electrospinning.

FIG. 4 shows surface images of an inner layer having a fiber radial mesh structure formed by electrospinning of a bone regeneration membrane according to the present invention, when polycaprolactone (PCL) that is a pharmaceutical polymer is used alone and when a mixture of PCL and BCP prepared by using the zol-gel method in a ratio of

25:75 is used, respectively.

Based on EDX element mapping analysis results with respect to each case, it can be seen that, when BCP is mixed with PCL, Ca ions are uniformly distributed in the entire mapping. In addition, since BCP has higher affinity with respect to osteoblast, when

BCP is mixed with PCL, the attachment capability of osteoblast is greater than when

PCL alone is used.

FIG. 5 shows surface images of an inner layer of a bone regeneration membrane according to the present invention, wherein the inner layer is formed by electrospinning the mixture of PCL and BCP, when osteoblast is incubated in the bone regeneration membrane for one day. Referring to FIG. 1 , it can be seen that osteoblast is stably attached to the inner layer of the bone regeneration membrane. That is, after the osteoblast is incubated for one day, osteoblast is stably spread and amplified according to a fiber radial framework. The present invention will be described in further detail with reference to the following examples. These examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

<Examples 1 through 5> Manufacture of outer layer having a porous semi-permeable structure of a bone regeneration membrane by self-assembly In Examples 1 through 5, polycaprolactone (molecular weight of 80,000) was dissolved in a mixed solution including 75 weight% of chloroform and 25 weight% of methanol. Together with polycaprolactone, polystyrene-b-polybutadiene was used as an amphiphilic polymer. In this case, the amount of the amphiphilic polymer was 10 weight% based on polycaprolactone. These two materials were dissolved in an amount of 0.5 weight% based on the solvent. Then, 0.5 weight% of

2-hydroxyl-2-methyl-1-phenyl-propan-1-one that is a photo initiator was added to the solution.

The resultant solution was dropped in an amount of 5 ml to a glass plate having a diameter of 8 cm and spin-coating was performed at room temperature at a rotation rate of 500 rpm, thereby forming a thin film. The glass plate coated with the thin film was immediately placed into a chamber having humidity of 80% and then, vapor was supplied to the chamber at a supply rate of 0.2 toi .O L/min for 10 seconds and the thin film was taken out of the chamber. Subsequently, the thin film was placed in a UV-radiation chamber and then left to sit for about 10 in order to perform a photopolymerization, thereby forming a semi-permeable film having regularly arranged fine pores. [Table 1 ]

Pore characteristics of outer layer having the porous semi-permeable structure of a bone regeneration membrane formed by self-assembly, according to the supply rate of vapor

As shown in Table 1 , when vapor is not supplied, no pores are formed, and as the supply rate of the vapor is increased, the pore size is increased.

When the supply rate of vapor is increased, vapor particles are combined to each other to form a larger vapor particle, thereby forming a larger pore. However, when the vapor supply rate exceeds a threshold vapor supply rate, that is, when the vapor supply rate exceeds 1.0 L/min, too large vapor particles are formed and thus pores are irregularly arranged.

Through Examples 1 through 5, it can be identified that when the vapor supply rate is maintained to be 0.2 L/min, the most regularly arranged and smallest pores can be effectively obtained.

<Examples 6 through 9> Manufacture of Inner layer of bone regeneration membrane by electrospinning

In Examples 6 through 9, polycaprlactone was dissolved at a concentration of 5 to 7.5 weight% in a mixed solution including 75 weight% of chloroform and 25 weight% of methanol, thereby producing a polymer starting solution.

To manufacture a BCP calcium phosphate solution by using a zol-gel method, a Ca/P mole ratio was controlled to be 1.55. 0.02 mol of Ca(NO₃)₂4H₂O was dissolved in 0.2 mol of methanol to prepare a Ca starting material. 0.013 mol of P(OC₂Hs)₃ as a P starting material was dissolved in 0.13 mol of methanol and then, 0.065 mol of distilled water was added thereto and the resultant solution was stirred for two hours, thereby performing a hydrolysis reaction.

The P starting material in which the hydrolysis reaction was finished was slowly dropped to the Ca starting material while stirring for 30 minutes, and then the reaction product was aged at a temperature of 35 ^°C for 3 days, thereby producing a BCP starting solution.

The prepared polycaprolactone solution was mixed with the BCP starting solution in weight ratios of 75:25 and 25:75, and then each of the resultant solutions was loaded to a syringe and the syringe was connected to an automatic syringe pump in order to perform electrospinning.

For the electrospinning, a distance between an end of a nozzle of the syringe and a plane electrode was controlled to be 13 cm, and the outer layers of the bone regeneration membrane formed by self-assembly prepared according to Examples 1 through 5 were placed on the plane electrode. The electrospinning was slowly performed by supplying the resultant solution at a supply rate of 1.0 ml/h at a voltage of 20 kV in humidity of 30 to 40%, thereby manufacturing an inner layer having a fiber radial structure of a bone regeneration membrane. The bone regeneration membrane formed by electrospinning was dried at a temperature of 60 to 150 ^°C for 10 to 60 minutes. [Table 2]

Pore characteristics according to vapor supply rate, when an inner layer is formed by electrospinning

When PCL alone was electrospun and the concentration of PCL was 5 weight%, an agglomeration phenomenon, such as formation of large beads at junctions of radial fibers, occurred. However, when the concentration of PCL was increased to 7.5 weight%, a very smooth fiber radial structure was able to be obtained.

However, in the case in which 75 weight% of BCP was added, when the concentration of PCL added was 5 weight%, a relatively smooth radial structure was able to be obtained, and when the concentration of PCL added was 3 weight%, relatively rough and agglomeration phenomenon, which is also shown in the inner layer prepared according to Example 6, occurs. Thus, it can be seen that the latter case is not suitable for a bone regeneration membrane.

Also, on an osteoblast attachment test, the attachment capability of osteoblast was higher when BCP was added than when PCL alone was used.

When an inner layer of a bone regeneration membrane is formed by electrospinning according to Examples 6 through 9, the most appropriate radial structures were able to be formed when 75 weight% of BCP was added and when the concentration of PCL was 5 weight%. [Industrial Applicability]

The present invention can be applied in a variety of technical fields including a bone regeneration membrane and a method of manufacturing the same

Claims

[CLAIMS] [Claim 1]

A bone regeneration membrane comprising: an outer layer having a porous semi-permeable structure, the outer layer comprising a pharmaceutical biodegradable polymer and an amphiphilic polymer having a hydrophilic group and a hydrophobic group; and an inner layer having a fiber radial mesh structure, the inner layer comprising a mixture of a pharmaceutical biodegradable polymer and a calcium phosphate, wherein the inner layer is formed on the outer layer.

[Claim 2]

The bone regeneration membrane of claim 1 , wherein the pharmaceutical biodegradable polymer used to form the outer layer or the pharmaceutical biodegradable polymer used to form the inner layer comprises at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

[Claim 3] The bone regeneration membrane of claim 1 , wherein the amphiphilic polymer is a compound represented by Formula 1: (Formula 1)

in

where M comprises at least one compound selected from the group consisting of 4-vinylpyridine, butadiene, polybutadiene, methacrylic acid, dodecylacrylamide, ω-carboxyhexylacrylamide, polyparapheylene, polythiophene, poly-3-hexylthiophene, polymethylmethacrylate, polyethylene oxide, polyvinylidene fluoride, polyacrylamide, and poly-N.N dimethylacrylamide, and a ratio of n : m is in a range of 2:1 to 5:1.

[Claim 4]

The bone regeneration membrane of claim 1 , wherein the outer layer has a pore size in a range of 200 nm to 50 μm.

[Claim 5]

The bone regeneration membrane of claim 1 , wherein the outer layer having the porous semi-permeable structure is formed by self-assembly.

[Claim 6]

The bone regeneration membrane of claim 1 , wherein, in the mixture of the pharmaceutical biodegradable polymer and the calcium phosphate, the calcium phosphate is added in a form of a solution prepared by using a zol-gel method.

[Claim 7]

The bone regeneration membrane of claim 6, wherein the solution prepared by using the zol-gel method is a biodegradable calcium phosphate-based solution selected from hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP).

[Claim 8]

The bone regeneration membrane of claim 1 , wherein the inner layer is formed by electrospinning.

[Claim 9]

A method of manufacturing a bone regeneration membrane, the method comprising: adding an amphiphilic polymer having a hydrophilic group and a hydrophobic group to a first pharmaceutical biodegradable polymer to prepare a mixture and stirring the mixture to prepare a solution; coating the solution on a substrate to form a film; adsorbing vapor particles to the film; polymerizing the film to which vapor particles are adsorbed in order to evaporate the vapor particles, thereby forming an outer layer having a porous semi-permeable structure; preparing a calcium phosphate solution; mixing the calcium phosphate solution and a second pharmaceutical biodegradable polymer; and forming an inner layer having a fiber radial mesh structure on the outer layer having the porous semi-permeable structure by using the mixture of the calcium phosphate solution and the second pharmaceutical biodegradable polymer.

[Claim 10]

The method of claim 9, wherein the first pharmaceutical biodegradable polymer or the second pharmaceutical biodegradable polymer comprises at least one polymer selected from the group consisting of poly(lactic acid), poly(-L-lactic acid), poly(-DL-lactic acid), copoly(lactide-mandelate), poly(glycolic acid), poly(β-hydroxybutyrate), poly(η-caprolactone), poly(ε-caprolactone), poly(dioxanone-ε-caprolactone), poly(lactic-co-glycolic acid), poly(lactide-co-glycolide)-ε-carprolactone, poly(trimethylene carbonate) and poly(orthoesters), or a co-polymerization derivative thereof.

[Claim 11]

The method of claim 9, wherein the amphiphilic polymer is represented by

Formula 1 :

(Formula 1)

where M comprises at least one compound selected from the group consisting of 4-vinylpyridine, butadiene, polybutadiene, methacrylic acid, dodecylacrylamide, ω-carboxyhexylacrylamide, polyparapheylene, polythiophene, poly-3-hexylthiophene, polymethylmethacrylate, polyethylene oxide, polyvinylidene fluoride, polyacrylamide, and poly-N,N dimethylacrylamide, and a ratio of n : m is in a range of 2:1 to 5:1.

[Claim 12]

The method of claim 9, wherein an amount of the amphiphilic polymer is in a range of 1 to 30 parts by weight based on the first pharmaceutical biodegradable polymer.

[Claim 13]

The method of claim 9, wherein the film is formed by spin-coating.

[Claim 14]

The method of claim 9, wherein vapor particles are adsorbed to the film in a chamber having a controlled humidity in a range of 20% to 90%.

[Claim 15]

The method of claim 9, wherein the film to which vapor particles are adsorbed is subjected to thermal polymerization or photopolymerization.

[Claim 16] The method of claim 9, wherein the outer layer has a pore size in a range of 200 nm to 50 JMΠ.

[Claim 17]

The method of claim 9, wherein the calcium phosphate solution is prepared by using a zol-gel method.

[Claim 18]

The method of claim 17, wherein the solution prepared by using the zol-gel method is a biodegradable calcium phosphate-based solution selected from hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP).

[Claim 19] The method of claim 17, wherein the calcium phosphate solution is prepared by using the zol-gel method while the mole ratio of calcium (Ca) and phosphate (P) is controlled to be in a range of 0.5 to 2.0.

[Claim 20] The method of claim 19, wherein a starting material of the Ca comprises at least one material selected from the group consisting of Ca(NO₃)₂4H₂O, and Ca(OC₂Hs)₂, and a starting material of the P comprises at least one material selected from the group consisting of P(OC₂H₅)₃, P(OCH₃)₃, OP(OC₂Hs)₃, and OP(OCH₃)₃.

[Claim 21] The method of claim 20, wherein the zol-gel method used to prepare the calcium phosphate solution comprises reacting Ca(NO₃)₂4H₂O with P(OC₂Hs)₃ and aging the reaction product.

[Claim 22]

The method of claim 9, wherein the calcium phosphate solution is mixed with the second pharmaceutical biodegradable polymer in a ratio of 10:90 to 90:10.

[Claim 23]

The method of claim 9, wherein the inner layer having the fiber radial mesh structure is formed by electrospinning.

[Claim 24] The method of claim 23, wherein the electrospinning is performed by applying a voltage in a range of 10 to 30 kV for 1 to 60 minutes while the mixture of the calcium phosphate solution and the second pharmaceutical biodegradable polymer is supplied at a supply rate in a range of 0.5 to 3 ml/h.