Method for manufacturing keratoprosthesis using interfacial adhesion between optical unit and support unit having different characteristics

Abstract

The present disclosure relates to a method of manufacturing a keratoprosthesis exhibiting excellent physical properties by stabilizing the interface of an adhesive optical unit and a support unit through a keratoprosthesis mold and UV dose adjustment. The present disclosure can stably adhere an interface between the optical unit and the support unit by manufacturing the optical unit for 1-4 hours using low dose UV in the keratoprosthesis mold, thereby manufacturing the keratoprosthesis in which the optical unit and the support unit are integrated. The artificial cornea manufactured by the manufacturing method has a constant spherical shape and is convenient for center positioning, so that the success rate of an operation can be improved during the operation; the central part of the optical unit shows uniform and excellent physical properties, so that the physical safety in a human body can be further improved; moreover, the interface of the optical unit and the support unit shows excellent physical properties which are equivalent to about 100 times of the existing intraocular pressure, so that the separation of the optical unit and the support unit caused by intraocular pressure in the human body can be prevented at an early stage. Furthermore, by means of the manufacturing method, the eye appearance of a patient to which the artificial cornea is transplanted can be improved, and complications and side effects caused by adhesive substances can be reduced.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing an artificial cornea exhibiting superior physical properties by stabilizing the interface between an optical unit and a support unit. Background Technology

[0002] Artificial corneas are products used for patients with corneal damage. They require an optical unit (Core) to ensure visual field and a support unit (Skirt) to stably attach the optical unit to the eyeball.

[0003] In the prior art, there is no simple way to adhere the optical unit and the support unit. Therefore, methods such as inserting and fixing the cornea between a metal material and a plastic material, or using nylon sutures to combine the optical unit and the support unit have been used.

[0004] However, the manufacturing process of the above methods is quite complex, which leads to an increase in product size. This can result in an eyeball that looks different from that of a normal person after corneal surgery, which may lead to a decline in the patient's self-confidence and social adaptability.

[0005] In addition, this method has drawbacks, such as the inability to avoid infection caused by foreign objects after surgery, because it uses metals and sutures that are not materials required for artificial corneas.

[0006] To address this issue, the academic community has proposed various methods for the adhesion of the interface between the optical unit and the support unit, such as plasma technology and graft polymerization. However, these methods only impart a small amount of adhesion between the interfaces, exhibiting properties lower than the individual physical properties of the optical unit and the support unit. Therefore, they have limitations in practical applications.

[0007] Therefore, there is an urgent need to develop a technique suitable for artificial corneas that allows for the adhesion of the optical unit and the support unit without the use of other materials, thereby improving the patient's ocular appearance and reducing complications and side effects caused by adhesive substances. Furthermore, in artificial corneal surgery, after a semi-circular incision of the anterior corneal lamina, the posterior corneal lamina is removed in a 3.5mm~5.5mm disc shape to remove the cloudy cornea. After adjusting the central portion of the posterior corneal lamina and the center of the artificial cornea to be as centrally located as possible, the anterior corneal lamina is covered, and the visual field is ensured by the incision of the anterior corneal lamina.

[0008] During this process, if the artificial cornea is not accurately centered, there is a possibility of secondary side effects due to the inability to match the basement cornea with the designed radius of curvature, and light may not be refracted as expected, resulting in the inability to form an image on the lens.

[0009] In more serious cases, there is even a risk that the artificial cornea may leak into the excised anterior lamina.

[0010] Therefore, a technique for stabilizing the shape is also needed to enable the artificial cornea to be used as designed.

[0011] Existing technical documents

[0012] Patent documents

[0013] (Patent Document 1) KR 10-2016-0140687 (2016-10-27) Summary of the Invention

[0014] Technical issues

[0015] In order to provide a method for manufacturing an artificial cornea that can adhere the optical unit and the support unit without the use of other substances, while providing a stable shape and excellent physical properties, the inventors of this disclosure conducted in-depth research and found that if only a portion of the optical unit is manufactured by photopolymerization, and the remaining portion of the optical unit is manufactured together with the support unit by thermal polymerization, a double network can be formed between the interface of the optical unit and the support unit, thereby imparting adhesion. This confirmed that an artificial cornea with excellent physical properties can be manufactured, thus completing this disclosure.

[0016] Therefore, the purpose of this disclosure is to provide a method for manufacturing an artificial cornea that exhibits a stable shape and excellent physical properties by stably adhering the interface between the optical unit and the support unit.

[0017] Solution to the problem

[0018] This disclosure provides a method for manufacturing an artificial cornea, the artificial cornea comprising the optical unit and the support unit. The manufacturing method may include: i) irradiating a mixture of acrylic monomers, a photoinitiator, a crosslinking agent, methanol, and distilled water under UV light at 5-40 W and 300-400 nm for 1-4 hours to perform photopolymerization, thereby manufacturing the optical unit; and ii) adding a mixture of acrylic monomers, distilled water, dimethylformamide, a crosslinking agent, a thermal initiator, and N,N,N',N'-tetramethylethylenediamine to the manufactured optical unit, and performing thermal polymerization at 30-100°C for 30 minutes to 2 hours, thereby manufacturing the support unit in a bonded state with the optical unit.

[0019] According to a preferred embodiment of the present disclosure, in step i), the acrylic monomer can be mixed at 70-90% by weight, the photoinitiator can be mixed at 0.1-3% by weight relative to the monomer, and the crosslinking agent can be mixed at 0.1-0.3% by weight relative to the monomer.

[0020] According to a preferred embodiment of the present disclosure, in step ii), the acrylic monomer can be mixed at 15-35% by weight, the crosslinking agent can be mixed at 1-3% by weight relative to the monomer, the thermal initiator can be mixed at 3-6% by weight relative to the monomer, and the N,N,N',N'-tetramethylethylenediamine can be mixed at 2-4% by weight relative to the monomer.

[0021] According to a preferred embodiment of this disclosure, the acrylic monomer may be selected from any one or more of the group consisting of methyl methacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane triacrylate, 1,4-butanediol diacrylate, ethylhexyl acrylate, glycidyl methacrylate, ethyleneglycol dimethacrylate, and 1,6-hexanediol diacrylate.

[0022] According to a preferred embodiment of the present disclosure, the photoinitiator in step i) may be selected from any one or more of the group consisting of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 1-hydroxycyclohexylphenylketone, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0023] According to a preferred embodiment of the present disclosure, the crosslinking agent in step i) may be selected from one or more of the group consisting of pentaerythritol tetraacrylate, pentaerythritol triacrylate, N,N'-methylenebisacrylamide, and EGDMA (ethylene glycol dimethacrylate).

[0024] According to a preferred embodiment of this disclosure, the distilled water and methanol in step i) can be mixed in a weight ratio of 75~95:5~25.

[0025] According to a preferred embodiment of this disclosure, in step i), 80-99% of the optical units can be manufactured by photopolymerization alone.

[0026] According to a preferred embodiment of this disclosure, the distilled water and dimethylformamide in step ii) can be mixed in a weight ratio of 70-90:10-30.

[0027] According to a preferred embodiment of this disclosure, the crosslinking agent in step ii) may be selected from one or more of the group consisting of pentaerythritol tetraacrylate, pentaerythritol triacrylate, N,N'-methylenebisacrylamide, and EGDMA (ethylene glycol dimethacrylate).

[0028] According to a preferred embodiment of this disclosure, the thermal initiator in step ii) may be ammonium persulfate and / or potassium persulfate.

[0029] Furthermore, this disclosure may also provide the artificial cornea manufactured by the manufacturing method described herein.

[0030] According to a preferred embodiment of this disclosure, the tensile strength of the boundary between the optical unit and the support unit of the artificial cornea can be 100~200 kPa.

[0031] According to a preferred embodiment of this disclosure, the total diameter of the artificial cornea can be 7-9 mm, the diameter of the optical unit can be 3-6 mm, and the vertex thickness can be 0.4-0.6 mm.

[0032] According to a preferred embodiment of this disclosure, the radius of curvature of the artificial cornea can be 7.5~8.0 mm in the front and 6.0~7.0 mm in the back.

[0033] Furthermore, this disclosure also provides a method for manufacturing an artificial cornea, the artificial cornea comprising the optical unit and the support unit, the manufacturing method comprising: i) dispensing a mixture of acrylic monomers, photoinitiator, crosslinking agent, methanol and distilled water into a lower mold and then combining it with an upper mold, and irradiating it under UV light at 5-40 W and 300-400 nm for 1-4 hours to perform photopolymerization, thereby manufacturing the optical unit; and ii) adding a mixture of acrylic monomers, distilled water, dimethylformamide, crosslinking agent, thermal initiator and N,N,N',N'-tetramethylethylenediamine into the lower mold on which the optical unit is formed, and then performing thermal polymerization at 30-100°C for 30 minutes to 2 hours, thereby manufacturing the support unit in a bonded state with the optical unit.

[0034] According to a preferred embodiment of this disclosure, step ii) can be performed continuously without separating the upper mold and the lower mold.

[0035] The effects of the invention

[0036] This disclosure allows for the fabrication of the optical unit within 1-4 hours using low-dose UV light, thereby enabling stable adhesion of the interface between the optical unit and the support unit, and ultimately creating an integrated artificial cornea comprising the optical unit and the support unit. The artificial cornea fabricated using this method can possess a constant spherical shape, facilitating central positioning and improving surgical success rates. The central portion of the optical unit exhibits uniform and superior physical properties, further enhancing physical safety within the human body. Furthermore, the interface between the optical unit and the support unit exhibits superior physical properties equivalent to approximately 100 times the existing intraocular pressure, preventing early separation of the optical unit and support unit due to intraocular pressure within the body. Additionally, this fabrication method improves the ocular appearance of patients receiving the artificial cornea and reduces complications and side effects caused by adhesive substances. Attached Figure Description

[0037] Figure 1 The surgical procedure for the artificial cornea can be shown.

[0038] Figure 2a The optical unit of the artificial cornea, manufactured by irradiating it with 8W UV light for up to 2 hours, can be shown.

[0039] Figure 2b It can be shown that the central portion (80%~99%) and peripheral portion (1~20%) of the optical unit of the artificial cornea manufactured by irradiation with 8W UV for up to 2 hours are formed with different degrees of polymerization. The central portion of the optical unit can be 100% polymerized, while the peripheral portion can be polymerized only at the oligomer level.

[0040] Figure 3 The artificial cornea manufactured by irradiating it with 8W UV light for up to 2 hours can be shown.

[0041] Figure 4a The shape change of the optical unit with UV irradiation time can be shown.

[0042] Figure 4b The appearance of the artificial cornea manufactured by photopolymerization for more than 4 hours can be shown.

[0043] Figure 5a The optical unit of the artificial cornea, manufactured by irradiating it with 40W high-energy UV light for up to 2 hours, can be shown.

[0044] Figure 5b The artificial cornea can be shown as being manufactured by irradiating it with 40W high-energy UV light for up to 2 hours.

[0045] Figure 6 The artificial cornea, in which the optical unit and the support unit are adhered using oxygen plasma, can be shown.

[0046] Figure 7a A SEM image of the artificial cornea manufactured by irradiating it with 8W UV light for up to 2 hours can be shown. It can have a bead-like structure, and the surface roughness can increase cell adhesion.

[0047] Figure 7b The BCS (BeadsChain Scaffold) technology for the support unit of the artificial cornea described in this disclosure can be shown.

[0048] Figure 8 SEM images of the artificial cornea manufactured by irradiating it with 40W UV light for up to 2 hours can be shown.

[0049] Figure 9The tensile strength SS curves of the artificial cornea manufactured by photopolymerization and thermal polymerization (UV Polymerization + Thermopolymerization), photopolymerization and oxygen plasma (UV Polymerization + Oxygen Plasma), and photopolymerization only (UV Polymerization) can be shown.

[0050] Figure 10a The initial elastic modulus and maximum tensile strength of the artificial cornea manufactured by photopolymerization and thermal polymerization, photopolymerization and oxygen plasma, and photopolymerization only can be shown.

[0051] Figure 10b The maximum tensile strength of the artificial cornea manufactured according to the manufacturing method of this disclosure can be shown. It can be confirmed that the physical strength of the interface, through the combination of the optical unit (1390 kPa) and the support unit (40 kPa), can have physical properties of the optical unit-support unit interface (170 kPa) that are superior to the strength of the support unit.

[0052] Figure 10c The maximum tensile strength of the artificial cornea photopolymerized using 40W high-energy UV light can be shown. It can be confirmed that the maximum tensile strength at the interface is approximately 10 kPa, indicating that a relatively weak bond can occur.

[0053] Figure 10d The maximum tensile strength of the five optical units of the artificial cornea using 40W high-energy UV light can be shown (Sample 1: 1416 kPa, Sample 2: 1046 kPa, Sample 3: 1532 kPa, Sample 4: 957 kPa, Sample 5: 1042 kPa). It can be confirmed that their standard deviation is very large.

[0054] Figure 10e The maximum tensile strength of the five optical units of the artificial cornea manufactured according to the manufacturing method of this disclosure can be shown (sample 1: 1398 kPa, sample 2: 1351 kPa, sample 3: 1431 kPa, sample 4: 1356 kPa, sample 5: 1344 kPa). It can be confirmed that it exhibits uniform tensile strength.

[0055] Figure 11a A mold for manufacturing an artificial cornea, to which the artificial cornea manufacturing method of the present disclosure is applicable, may be shown.

[0056] Figure 11bA mold for manufacturing an artificial cornea, to which the artificial cornea manufacturing method of the present disclosure is applicable, can be shown. A first hole 11 may be formed in the center of the upper mold 10, into which a solution 12 for forming the optical unit may be inserted, and a second hole 13 may be formed in the periphery of the upper mold 10 for introducing a solution for forming the support unit. Furthermore, a plurality of lower fitting protrusions 21 for engaging with the upper mold 10 may be formed on the lower mold 20.

[0057] Figure 11c A mold for manufacturing an artificial cornea, to which the artificial cornea manufacturing method of the present disclosure is applicable, may be shown. A first hole 11 may be formed in the center of the upper mold 10, into which the solution 12 for forming the optical unit may be inserted, and a second hole 13 may be formed in the periphery of the upper mold 10 for introducing a thermosetting solution for forming the support unit.

[0058] Figure 11d A mold for manufacturing an artificial cornea, to which the artificial cornea manufacturing method of the present disclosure is applicable, may be shown. A plurality of lower fitting protrusions 21 for engaging with the upper mold 10 may be formed on the lower mold 20.

[0059] Figure 12 The sequence of manufacturing the artificial cornea using the mold for manufacturing the artificial cornea described in this disclosure can be shown.

[0060] Figure 13 The appearance of the artificial cornea manufactured according to this disclosure can be shown.

[0061] Figure 14 The detailed structure of the artificial cornea manufactured according to this disclosure can be shown (A: total diameter, B: optical unit diameter, C: vertex thickness, D: anterior radius of curvature, E: posterior radius of curvature).

[0062] Figure 15 Results confirming the in vitro cell proliferation effect of the artificial cornea manufactured according to this disclosure can be shown.

[0063] Figure 16 Results can be shown confirming the in vivo biocompatibility and cell proliferation effect of the artificial cornea manufactured according to this disclosure.

[0064] Figure 17 The results of transplanting the artificial cornea manufactured according to this disclosure onto a rabbit can be shown.

[0065] Figure 18The results of transplanting the artificial cornea manufactured according to this disclosure onto a primate can be shown. Detailed Implementation

[0066] To integrate the optical unit and the support unit, bio-adhesives or sutures are typically used. However, due to the soft tissue characteristics of the artificial cornea, which is not rigid but flexible, the bonding site may become unstable when using bio-adhesives, while sutures may pose a risk of tearing due to their narrow surface area. Furthermore, using additional materials for fusion may increase the risk of infection and unnecessary surgical procedures.

[0067] Furthermore, when the inventors of this disclosure use high-energy UV to manufacture the artificial cornea, the central portion (center) of the artificial cornea may be inconsistent (see reference). Figure 5b This may be because the reaction occurs unevenly when using a high-energy UV lamp for photopolymerization, resulting in deformation of the shape of the optical unit.

[0068] Therefore, in order to fuse the optical unit and the support unit, the inventors of this disclosure modified the polymerization conditions of the optical unit, simultaneously polymerizing both the optical unit and the support unit during the polymerization process, thereby manufacturing the artificial cornea. In this disclosure, the degree of polymerization of the central portion (80%~99%) and the peripheral portion (1~20%) of the optical unit can be adjusted differently by irradiating it with weak light. The central portion of the optical unit, which is concentratedly exposed to weak light, can have 100% polymerization, without affecting the transparency and physical properties used to ensure visual field, while the peripheral portion, which is relatively less exposed to light, can polymerize only at the oligomer level, thus possessing liquid properties. Subsequently, when the support unit solution is added, it can mix with the peripheral portion of the optical unit, which can undergo additional thermal polymerization together with the support unit due to the presence of the thermal initiator (APS) in the support unit solution. Finally, the peripheral portion of the optical unit and the support unit solution can polymerize simultaneously and can be fused in a double network form to form the artificial cornea.

[0069] When the artificial cornea is manufactured using the method of this disclosure, the interface between the optical unit and the support unit can be bonded, resulting in higher tensile strength at the interface and superior physical properties compared to bonding using oxygen plasma, a common method that bonds different interface surfaces. Furthermore, the support unit of this disclosure can be in a bead-like interweaving pattern with a rough surface texture, imparting porosity that optimizes cell growth. In particular, the artificial cornea manufactured using the method of this disclosure can be bonded to the eyeball using a sutureless cell scaffold, thereby minimizing secondary infections and foreign body reactions caused by sutures. Moreover, due to its structure where autologous cells infiltrate into the cell scaffold and grow spontaneously, immune rejection is minimized.

[0070] Furthermore, when the artificial cornea is manufactured using the method of this disclosure, it can be confirmed that the central portion (center) of the artificial cornea can be uniform. This is likely because the central portion is irradiated with generally low-energy UV light, resulting in a more uniform reaction formation.

[0071] Conversely, when the optical unit and the support unit are polymerized separately using 40W high-energy UV, the optical unit can be 100% polymerized and cannot fuse with the support unit solution. Thus, it can be confirmed in the actual SEM image that the interface between the optical unit and the support unit has not bonded, and that the tensile strength and physical properties of the interface are very low.

[0072] Therefore, this disclosure can provide a method for manufacturing an artificial cornea, the artificial cornea including the optical unit and the support unit, the manufacturing method including: i) irradiating a mixture of acrylic monomers, photoinitiator, crosslinking agent, methanol and distilled water under UV light at 5-40 W and 300-400 nm for 1-4 hours and performing photopolymerization to manufacture the optical unit; and ii) adding a mixture of acrylic monomers, distilled water, dimethylformamide, crosslinking agent, thermal initiator and N,N,N',N'-tetramethylethylenediamine to the manufactured optical unit and performing thermal polymerization at 30-100°C for 30 minutes to 2 hours to manufacture the support unit in a bonded state with the optical unit.

[0073] Preferably, the photopolymerization in step i) can be performed by irradiating with 7-10 W and 350-380 nm UV for 2-3 hours, and the thermal polymerization in step ii) can be performed at 30-40°C for 50-70 minutes.

[0074] In step i), if UV (ultraviolet) irradiation is less than 1 hour, polymer formation may not occur, thus failing to maintain the full physical properties of the optical unit. The target thickness of the optical unit can be 0.5 mm, most similar to that of the human body, but when photopolymerization is performed for less than 1 hour, the thickness may decrease to less than 0.3 mm. Conversely, when irradiation is performed for more than 4 hours, the optical unit can be completely polymerized (cured), thus the bonding between the optical unit and the support unit may not be possible (see reference). Figure 4b ).

[0075] The N,N,N',N'-tetramethylethylenediamine in step ii) may be included to regulate the reaction rate at the interface.

[0076] According to a preferred embodiment of this disclosure, in step i), the acrylic monomers may be mixed at 70-90% by weight, the photoinitiator may be mixed at 0.1-3% by weight relative to the monomers, and the crosslinking agent may be mixed at 0.1-0.3% by weight relative to the monomers; and in step ii), the acrylic monomers may be mixed at 15-35% by weight, the crosslinking agent may be mixed at 1-3% by weight relative to the monomers, the thermal initiator may be mixed at 3-6% by weight relative to the monomers, and the N,N,N',N'-tetramethylethylenediamine may be mixed at 2-4% by weight relative to the monomers.

[0077] Preferably, the acrylic monomer in step i) may be included in 75-85% by weight, and the acrylic monomer in step ii) may be included in 20-30% by weight.

[0078] According to a preferred embodiment of this disclosure, the acrylic monomer may be selected from one or more of the group consisting of methyl methacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane triacrylate, 1,4-butanediol diacrylate, ethylhexyl acrylate, glycidyl methacrylate, ethyleneglycol dimethacrylate, and 1,6-hexanediol diacrylate. Preferably, the acrylic monomer may be methyl methacrylate or 2-hydroxyethyl methacrylate.

[0079] Specifically, the acrylic monomer in step i) may contain 2-hydroxyethyl methacrylate and methyl methacrylate in a ratio of 8 to 10:1 to 2, and the acrylic monomer in step ii) may contain 2-hydroxyethyl methacrylate and methyl methacrylate in a ratio of 7 to 10:1 to 3.

[0080] When the content of the photoinitiator in step i) is less than 0.1% by weight relative to the monomer, polymerization of the monomer may not be performed; however, when it exceeds 3% by weight relative to the monomer, the reaction can proceed rapidly, thereby polymerizing all parts of the optical unit, resulting in a weak effect of generating polymer-oligomers according to UV intensity, and thus preventing adhesion caused by photopolymerization and thermal polymerization.

[0081] According to a preferred embodiment of this disclosure, the photoinitiator in step i) may be any substance containing a hydroxyalkyl ketone group, but preferably may be selected from any one or more of the group consisting of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959), 1-hydroxycyclohexylphenylketone (Irgacure 184), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 819). More preferably, the photoinitiator in step i) can be 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959).

[0082] When the content of the crosslinking agent in step i) is less than 0.1% by weight relative to the monomer, the optical unit may be fluid, which may lead to the possibility of detachment from the surgical site, and the degree of swelling may increase, making it difficult to control the thickness or diameter, etc.; while when it exceeds 0.3% by weight relative to the monomer, the flexibility of the optical unit may decrease, which may lead to the risk of easy breakage, and the light transmittance may decrease due to crystallization.

[0083] According to a preferred embodiment of this disclosure, the crosslinking agent in step i) may be selected from one or more of the group consisting of pentaerythritol tetraacrylate, pentaerythritol triacrylate, N,N'-methylenebisacrylamide, and ethylene glycol dimethacrylate (EGDMA). Preferably, the crosslinking agent in step i) may be ethylene glycol dimethacrylate (EGDMA).

[0084] According to a preferred embodiment of this disclosure, the distilled water and methanol in step i) can be mixed in a weight ratio of 75~95:5~25. Preferably, the distilled water and methanol in step i) can be mixed in a weight ratio of 80~90:10~20.

[0085] According to a preferred embodiment of this disclosure, in step i), 80-99% of the optical units can be manufactured by photopolymerization alone.

[0086] According to a preferred embodiment of this disclosure, the distilled water and dimethylformamide in step ii) can be mixed in a weight ratio of 70-90:10-30. Preferably, the distilled water and dimethylformamide in step ii) can be mixed in a weight ratio of 75-85:15-25.

[0087] According to a preferred embodiment of this disclosure, the crosslinking agent in step ii) may be selected from one or more of the group consisting of pentaerythritol tetraacrylate, pentaerythritol triacrylate, N,N'-methylenebisacrylamide, and EGDMA (ethylene glycol dimethacrylate). Preferably, the crosslinking agent in step ii) may be pentaerythritol tetraacrylate.

[0088] According to a preferred embodiment of this disclosure, the thermal initiator in step ii) can be ammonium persulfate and / or potassium persulfate. Preferably, the thermal initiator in step ii) can be ammonium persulfate. The thermal initiator can be included in 1 to 10% by weight relative to the monomer, preferably in 3 to 6% by weight. When the thermal initiator is less than 3% by weight relative to the monomer, interfacial polymerization may not be formed; while when the content relative to the monomer is 6% or more, the thermal initiator may affect the physical properties of the support unit.

[0089] According to a preferred embodiment of this disclosure, step ii) can be performed continuously without separating the upper mold and the lower mold.

[0090] Furthermore, the mold used in the manufacturing method of this disclosure for manufacturing an artificial cornea may include an upper mold (10) and a lower mold (20) to enable the continuous manufacturing of the optical unit and the support unit of the artificial cornea within a single mold, allowing photopolymerization and thermal polymerization to occur simultaneously. A first hole (11) may be formed in the central portion of the upper mold (10), into which a solution (12) for forming the optical unit may be inserted. A second hole (13) may be formed at the periphery of the upper mold (10) for introducing a thermosetting solution for forming the support unit. Additionally, a plurality of lower fitting protrusions (21) may be formed on the lower mold (20) for engaging with the upper mold (10).

[0091] The upper and lower molds can be made of quartz and anodized aluminum. The quartz has a radius of curvature of 6.5 mm for the lower portion and 7.8 mm for the upper portion, which are used to manufacture the artificial cornea, thus allowing it to be configured to achieve a curvature similar to that of the human body. The curvature characteristic of the quartz allows the artificial corneal optical unit to also be endowed with the same curvature, enabling it to integrate naturally with the existing cornea upon insertion into the human body, and providing an optimized structure capable of withstanding intraocular pressure caused by the curvature of the human body.

[0092] Because quartz is very small, only 4-6 mm, the addition of anodized aluminum facilitates the joining and separation of the upper and lower molds. Furthermore, by forming interlocking protrusions around the periphery of the upper and lower molds, the thickness of the artificial cornea can be adjusted to 0.5 mm. Aluminum has excellent corrosion resistance and oxidation resistance compared to other metals, thus possessing the advantage of not being corroded by chemical substances. Based on this, a 25 µm anodized coating can be applied to further enhance corrosion resistance and abrasion resistance.

[0093] The present disclosure will now be described in more detail through embodiments. These embodiments are merely illustrative and will be readily apparent to those skilled in the art that the scope of the disclosure should not be construed as limited to these embodiments.

[0094] [Example 1]

[0095] Manufacturing of the artificial cornea using photopolymerization and thermal polymerization optical units

[0096] <1-1> Manufacturing of the artificial cornea

[0097] When manufacturing the optical unit of the artificial cornea, it is possible to aim to confirm the photopolymerization conditions.

[0098] Specifically, to manufacture the optical unit, 2-hydroxyethyl methacrylate and methyl methacrylate can be fixed in a weight ratio of 10:1 and dissolved in a mixture of distilled water and methanol to prepare a solution. In this case, the weight ratio of 2-hydroxyethyl methacrylate to methyl methacrylate relative to the total solution can be adjusted to 77% by weight. Furthermore, the weight ratio of distilled water to methanol can be adjusted to 85 parts by weight and 15 parts by weight, respectively.

[0099] In the solution, 1.2% by weight of Irgacure 2959 (2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone) and 0.12% by weight of ethylene glycol dimethacrylate (EGDMA) relative to the monomer content can be added, and it can be cured for 2 hours under a 365nm UV lamp at 8W.

[0100] The results confirmed by the projector show that when manufactured at 8W, only about 80% to 99% of the optical units undergo photopolymerization and solidification, while the remaining 1% to 20% of the optical units exist as oligomers in a liquid state (see reference). Figure 2a , Figure 2b ).

[0101] To prepare the optical unit manufactured at 8W, a solution can be prepared by dissolving 80 parts by weight of 2-hydroxyethyl methacrylate and 20 parts by weight of methyl methacrylate, which serve as the support unit manufacturing solution, in a mixture of distilled water and dimethylformamide. In this case, the ratio of the two monomers can be adjusted to 25% by weight relative to the total volume, and the ratios of the distilled water and dimethylformamide as solvents can be adjusted to 80 parts by weight and 20 parts by weight, respectively.

[0102] In the solution, 1.28 wt% of pentaerythritol tetraacrylate as a crosslinking agent, 4.6 wt% of ammonium persulfate as an initiator, and 2.3 wt% of N,N,N',N'-tetramethylethylenediamine can be added relative to the monomer, and thermal polymerization can be carried out in a drying oven at 37°C for 1 hour to produce a polymer (see reference). Figure 3 ).

[0103] <1-2> Comparison of manufacturing time of the artificial corneal optical unit

[0104] It can be aimed at confirming the change in the shape of the optical unit as the photopolymerization time increases.

[0105] When manufacturing the artificial corneal optical unit, the irradiation time can be set to 0 minutes, 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours, and 10 hours, thereby confirming the shape changes of the optical unit.

[0106] The result, such as Figure 4a As shown, it can be confirmed that the liquid state was completely liquid before photopolymerization.

[0107] After photopolymerization, curing can begin within 15 to 30 minutes. However, experiments conducted using the photopolymerization results to fabricate the artificial cornea confirmed that the unpolymerized portions were washed away during the cleaning process, and the center thickness of the optical unit could be less than 0.3 mm, which differs from the 0.5 mm thickness of the human cornea.

[0108] When the corneal thickness differs from the average human corneal thickness of 0.5 mm, the amount of light refraction in the cornea can change, which can lead to a change in the amount of light transmitted to the lens.

[0109] From one hour onwards, the central thicknesses of all the optical units, from sample 1 to sample 5, were 0.486, 0.495, 0.511, 0.502, and 0.522 mm respectively, confirming that they became similar to the average thickness of the human body. At this point, in the total volume of the optical units, the degree to which the center of the optical units was completely polymerized was approximately 80%, and the degree of oligomerization was approximately 20%.

[0110] After 4 hours, approximately 95-99% of the material can be fully polymerized, while approximately 1-5% can be oligomerized.

[0111] Starting from 6 hours later, it can be confirmed that the polymerization of all the aforementioned optical units is 100% complete. Furthermore, it can be confirmed that shape deformation can occur due to further bonding between the polymers.

[0112] Furthermore, during the process after 4 hours, all the optical units can be polymerized and cannot undergo further polymerization, thereby reducing the physical properties of the boundary between the optical units and the support units. This confirms that the optical units and the support units separate during extraction from the mold (see reference). Figure 4b ).

[0113] [Comparative Example 1]

[0114] Manufacturing of the artificial cornea using a photopolymerization optical unit

[0115] When manufacturing the optical unit, the artificial cornea can be manufactured using only photopolymerization.

[0116] Specifically, to manufacture the optical unit, 2-hydroxyethyl methacrylate and methyl methacrylate can be fixed in a weight ratio of 10:1 and dissolved in a mixture of distilled water and methanol to prepare a solution. In this case, the weight ratio of 2-hydroxyethyl methacrylate to methyl methacrylate relative to the total solution can be adjusted to 77% by weight. Furthermore, the weight ratio of distilled water to methanol can be adjusted to 85 parts by weight and 15 parts by weight, respectively.

[0117] The solution can be added with 1.2% by weight of Irgacure 2959 and 0.12% by weight of ethylene glycol dimethacrylate (EGDMA) relative to the monomer content, and can be cured for 2 hours under a 365nm UV lamp at 40W.

[0118] To prepare the optical unit manufactured at 40W, a solution can be prepared by dissolving 80 parts by weight of 2-hydroxyethyl methacrylate and 20 parts by weight of methyl methacrylate, which serve as the support unit manufacturing solution, in a mixture of distilled water and dimethylformamide. In this case, the ratio of the two monomers can be adjusted to 25% by weight relative to the total volume, and the ratios of the distilled water and dimethylformamide as solvents can be adjusted to 80 parts by weight and 20 parts by weight, respectively.

[0119] Furthermore, when manufactured at 40W, it can be confirmed that the optical unit is 100% polymerized (reference). Figure 5a ).

[0120] In the solution, 1.28 wt% of pentaerythritol tetraacrylate as a crosslinking agent, 4.6 wt% of ammonium persulfate as an initiator, and 2.3 wt% of N,N,N',N'-tetramethylethylenediamine as a crosslinking agent can be added, and thermal polymerization can be carried out in a drying oven at 37°C for 1 hour to produce a polymer (see reference). Figure 5b ).

[0121] [Comparative Example 2]

[0122] Manufacturing of the artificial cornea by adhering the optical unit and the support unit using oxygen plasma

[0123] The optical unit can be manufactured using the method described in Comparative Example 1 (cured for 2 hours under a 365nm UV lamp at 40W), and the support unit can be manufactured using the method described in Example 1 (a solution can be prepared by dissolving 80 parts by weight of 2-hydroxyethyl methacrylate and 20 parts by weight of methyl methacrylate in a mixture of distilled water and dimethylformamide. The ratio of the two monomers can be adjusted to 25% by weight relative to the total volume, and the ratio of the distilled water and dimethylformamide as solvents can be adjusted to 90 parts by weight and 10 parts by weight, respectively. In the solution, 1.28% by weight of pentaerythritol tetraacrylate (a crosslinking agent), 4.6% by weight of ammonium persulfate (an initiator), and 2.3% by weight of N,N,N',N'-tetramethylethylenediamine (an initiator) relative to the monomers can be added, and thermal polymerization can be carried out in a drying oven at 37°C for 1 hour to produce a polymer). The artificial cornea can then be manufactured by performing oxygen plasma treatment for 20 minutes using a plasma system most commonly used in interfacial adhesion (see reference). Figure 6 ).

[0124] [Example 2]

[0125] SEM image of the artificial cornea

[0126] After the artificial cornea manufactured in Example 1 is freeze-dried, the image can be measured using a miniature SEM at 15KV and 1000x magnification.

[0127] When photopolymerization and thermal polymerization are simultaneously applied to the optical unit, the support unit can polymerize outside the optical unit like the oligomer, allowing the support unit to easily penetrate into the oligomer. As a result, it can be confirmed that the optical unit and the support unit exhibit a double network morphology (see reference). Figure 7a , Figure 7b ).

[0128] Conversely, when the optical unit is manufactured solely through photopolymerization, the support unit solution may fail to penetrate the interior of the optical unit, instead polymerizing on the outside. This confirms that proper bonding has not occurred between the optical unit and the support unit (see reference). Figure 8 ).

[0129] [Example 3]

[0130] Physical properties of the artificial cornea confirmed

[0131] <3-1> Confirmation of the physical properties of the optical unit and the boundary of the support unit

[0132] It can be used to confirm the stress-strain rate and tensile strength of the boundaries of the optical unit and the support unit of the artificial cornea manufactured by various methods.

[0133] Specifically, a tensile strength measuring instrument can be used to measure the tensile strength of the optical unit and the support unit of the artificial cornea in Embodiment 1 and Comparative Example 1, as well as the boundary portion of the optical unit and the support unit of the artificial cornea in Embodiment 1, Comparative Example 1, and Comparative Example 2. In this case, a 6-piece (long) tensile strength sample composed of the optical unit and the support unit can be used. The sample is 3 cm wide, and the tensile strength measurement speed can be fixed at 5 mm / sec.

[0134] The result, such as Figure 9 and Figure 10a As shown, it can be confirmed that the stress-strain rate and tensile strength of the boundary portion of the optical unit and the support unit of the artificial cornea manufactured by the method of Example 1 can be the highest. Compared with the method using oxygen plasma (Comparative Example 2), which is the most common interface bonding method, the difference in maximum tensile strength can reach more than 3 times.

[0135] In particular, when the artificial cornea is manufactured using high energy of 40W (Comparative Example 1), it can be confirmed that the bonding strength at the boundary between the optical unit and the support unit can be very low. This could mean that after the artificial cornea surgery, the optical unit and the support unit may separate due to intraocular pressure.

[0136] Furthermore, compared to the boundary portion of the optical unit and the support unit of the artificial cornea manufactured by the method of Embodiment 1 of this disclosure (see reference...) Figure 10b It can be confirmed that the maximum tensile strength of the boundary between the optical unit and the support unit in Comparative Example 1 is approximately 10 kPa, indicating that a relatively weak bond can occur (see reference). Figure 10c ).

[0137] Since the average intraocular pressure in the human body is 1.87 kPa, the support unit, which is in contact with the human body, can exhibit mechanical safety through its combination with existing tissues, even if it has a relatively low value. However, the higher the physical properties of the optical unit and the optical unit-support unit boundary, which are not in contact with the human body, the better it can prevent the artificial cornea implanted in the human body from falling out and prevent mechanical deformation.

[0138] <3-2> Confirmation of the physical performance of the optical unit

[0139] After fabricating five optical units using the method described in Example 1 or Comparative Example 1, the maximum tensile strength can be measured to confirm whether uniform polymerization is exhibited.

[0140] As a result, the artificial cornea manufactured by the method of Comparative Example 1 failed to form uniform polymerization, resulting in a very large standard deviation of tensile strength (see reference). Figure 10d Conversely, it can be confirmed that the artificial cornea manufactured by the method of Embodiment 1 of this disclosure exhibits excellent tensile strength and bonding strength between the optical unit and the support unit through uniform polymerization (see reference). Figure 10e When the standard deviation of the physical properties of the optical unit is large, it can affect the safety of use.

[0141] [Example 4]

[0142] Manufacturing of the artificial cornea using a mold

[0143] The artificial cornea manufacturing method of Embodiment 1 can be applied to a mold for manufacturing an artificial cornea that is directly manufactured by the inventors of this disclosure, thereby enabling the manufacture of the artificial cornea.

[0144] Specifically, after rough machining of the aluminum base material using a 5-axis machining center, ultra-precision machining can be performed using a Nanotech 350FG freeform surface machining center to process and prepare the upper mold and the lower mold respectively.

[0145] At this time, the first hole can be formed in the center of the upper mold, and the second hole for inserting the thermosetting resin composition for forming the support unit can be formed in the periphery of the upper mold. Furthermore, a quartz UV-transmitting component (see reference) can be inserted into the first hole. Figures 11a-11d ).

[0146] In a solution prepared by fixing 2-hydroxyethyl methacrylate and methyl methacrylate in a weight ratio of 10:1 and dissolving them in a mixture of distilled water and methanol, 1.2% by weight of Irgacure 2959 and 0.12% by weight of ethylene glycol dimethacrylate (EGDMA) relative to the monomer content can be added, thereby preparing a solution for forming the optical unit.

[0147] The solution used to form the optical unit can be dispensed in 2µL into the center of the lower mold (quartz) using a 20µL pipette, and then combined with the upper mold. It can be cured for 2 hours at room temperature under a 365nm UV lamp at 8W.

[0148] At this point, the 2-hydroxyethyl methacrylate and the methyl methacrylate can be adjusted to 77% by weight relative to the total solution. Furthermore, the weight ratio of the distilled water and the methanol can be adjusted to 85 parts by weight and 15 parts by weight, respectively.

[0149] Continuously, in a solution prepared by dissolving 80 parts by weight of 2-hydroxyethyl methacrylate and 20 parts by weight of methyl methacrylate in a mixture of distilled water and dimethylformamide to form the support unit, 1.28% by weight of pentaerythritol tetraacrylate (a crosslinking agent), 4.6% by weight of ammonium persulfate (an initiator), and 2.3% by weight of N,N,N',N'-tetramethylethylenediamine (a tetramethylethylenediamine) relative to the monomers can be added and vortexed for 1 minute. Then, 130 µL can be inserted into a spaced mold using a 200 µL pipette and thermally polymerized in a drying oven at 37°C for 1 hour, thereby manufacturing the artificial cornea integrally composed of the optical unit and the support unit.

[0150] The ratio of the two monomers can be adjusted to 25% by weight relative to the total volume, and the ratio of the distilled water and the dimethylformamide as solvents can be adjusted to 80 parts by weight and 20 parts by weight, respectively.

[0151] Subsequently, the mold used to manufacture the artificial cornea can be hydrated in pure water for 24 hours to separate the upper and lower parts of the mold, thereby obtaining the artificial cornea (see reference). Figure 12 , Figure 13 ).

[0152] The artificial cornea manufactured may have the following characteristics (see reference). Figure 14 ).

[0153] Table 1

[0154] [Example 5]

[0155] Cell proliferation in the manufactured artificial cornea confirmed

[0156] This can be used to confirm the in vitro / in vivo cell proliferation effect of the artificial cornea manufactured by the manufacturing method of this disclosure.

[0157] Specifically, human fibroblasts can be co-cultured with the artificial cornea described in this disclosure and observed for 1, 3, and 7 days.

[0158] In addition, the artificial cornea described herein can be transplanted subcutaneously into rats, and H&E staining and M&T staining can be performed and observed after 3 and 6 weeks.

[0159] The results confirmed that the cells penetrated the scaffold and exhibited excellent biocompatibility and cell proliferation (see reference). Figure 15 , Figure 16 ).

[0160] [Example 6]

[0161] Animal model experiments

[0162] <6-1> Rabbit Model

[0163] The artificial cornea manufactured by the method disclosed herein can be transplanted into the eyes of 15 NZW rabbits.

[0164] Specifically, at weeks 4, 8, and 12 after the artificial cornea transplant, corneal H&E staining can be used to observe changes in the corneal surface, transplant site, and tissues in 5 rabbits, and corneal fibrosis can be observed using Marson trichrome staining.

[0165] As a result, it was confirmed that there was no inflammation, no visual field obstruction, and that the supporting unit and corneal cells successfully fused (see reference). Figure 17 ).

[0166] <6-2> Primate Model

[0167] The effectiveness of the study was evaluated using cynomolgus monkeys, starting from the fourth month post-transplantation and continuing for three months, using the following evaluation indicators.

[0168] No specific findings were observed in terms of general symptoms and weight changes, and the threat reflex examination results showed no difference in response compared to the non-transplanted eye.

[0169] Furthermore, no abnormalities were found in hematological and blood biochemistry tests, thus confirming safety.

[0170] Histopathological examination revealed corneal epithelial cell proliferation and fibroblast infiltration in the transplanted eye (see reference). Figure 18 ).

[0171] Industrial applicability

[0172] This disclosure allows for the fabrication of the optical unit within 1-4 hours using low-dose UV light, enabling stable adhesion of the interface between the optical unit and the support unit, thereby creating an integrated artificial cornea comprising the optical unit and the support unit. The artificial cornea fabricated using this method can possess a constant spherical shape, facilitating central positioning and improving surgical success rates. The central portion of the optical unit exhibits uniform and superior physical properties, further enhancing physical safety within the human body. Furthermore, the interface between the optical unit and the support unit exhibits superior physical properties equivalent to approximately 100 times the existing intraocular pressure, preventing early separation of the optical unit and support unit due to intraocular pressure within the body. In addition, this fabrication method improves the ocular appearance of patients receiving the artificial cornea and reduces complications and side effects caused by adhesive substances, thus possessing industrial applicability.

Claims

1. A manufacturing method of an artificial cornea including an optical unit and a supporting unit, characterized by, The manufacturing method includes: i) a step of manufacturing the optical unit by irradiating a mixed solution mixed with an acrylic monomer, a photoinitiator, a crosslinking agent, methanol, and distilled water under UV of 5 to 40 W and 300 to 400 nm for 1 to 4 hours and performing photopolymerization; and ii) a step of manufacturing the support unit in a bonded state with the optical unit by pouring a mixed solution mixed with an acrylic monomer, distilled water, dimethylformamide, a crosslinking agent, a thermal initiator, and N,N,N',N'-tetramethyl ethylenediamine into the manufactured optical unit and performing thermal polymerization at 30 to 100°C for 30 minutes to 2 hours.

2. The method for manufacturing an artificial cornea according to claim 1, characterized by, In the step i), the acrylic monomer is mixed at 70 to 90% by weight, the photoinitiator is mixed at 0.1 to 3% by weight with respect to the monomer, and the crosslinking agent is mixed at 0.1 to 0.3% by weight with respect to the monomer.

3. The method for manufacturing an artificial cornea according to claim 1, characterized by, In the step ii), the acrylic monomer is mixed at 15 to 35% by weight, the crosslinking agent is mixed at 1 to 3% by weight with respect to the monomer, the thermal initiator is mixed at 3 to 6% by weight with respect to the monomer, and the N,N,N',N'-tetramethyl ethylenediamine is mixed at 2 to 4% by weight with respect to the monomer.

4. The method for producing an artificial cornea according to claim 1, characterized by, The acrylic monomer is selected from any one or more of a group consisting of methyl methacrylate, 2-hydroxyethyl methacrylate, Trimethylolpropane Triacrylate, 1,4-Butanediol Diacrylate, Ethylhexyl acrylate, Glycidyl methacrylate, ethylene glycol dimethacrylate, and 1,6-hexanediol diacrylate.

5. The production method according to claim 1, characterized by, The photoinitiator of the step i) is selected from any one or more of a group consisting of 2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 1-Hydroxy-cyclohexyl-phenyl-ketone, and Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

6. The production method according to claim 1, characterized by, The cross-linking agent of the step i) is selected from any one or more of the group consisting of Pentaerythritol tetraacrylate, Pentaerythritol triacrylate, N,N'-Methylenebisacrylamide, and Ethylene glycoldimethacrylate (EGDMA).

7. The manufacturing method of claim 1, wherein, The distilled water and the methanol of the step i) are mixed in a weight ratio of 75~95: 5~25.

8. The production method according to claim 1, characterized by, 80~99% of the optical unit is manufactured by only photo-polymerization in the step i).

9. The production method according to claim 1, characterized by, The distilled water and the dimethylformamide of the step ii) are mixed in a weight ratio of 70~90: 10~30.

10. The production method according to claim 1, characterized by, The cross-linking agent of the step ii) is selected from any one or more of the group consisting of Pentaerythritol tetraacrylate, Pentaerythritol triacrylate, N,N'-Methylenebisacrylamide, and Ethylene glycoldimethacrylate (EGDMA).

11. The production method according to claim 1, characterized by, The thermal initiator of the step ii) is Ammonium Persulfate and / or Potassium persulfate.

12. The artificial cornea manufactured by the manufacturing method according to claim 1.

13. The artificial cornea according to claim 12, characterized in that, The tensile strength of the optical unit and the support unit interface of the artificial cornea is 100~200 KPa.

14. The artificial cornea according to claim 12, characterized by, The total diameter of the artificial cornea is 7~9 mm, the optical unit diameter is 3~6 mm, and the vertex thickness is 0.4~0.6 mm.

15. The artificial cornea according to claim 12, characterized by, The radius of curvature of the artificial cornea is 7.5~8.0 mm in the front and 6.0~7.0 mm in the back.

16. A method of manufacturing an artificial cornea including the optical unit and the support unit, characterized by, The manufacturing method comprises: i) a step of manufacturing the optical unit by injecting a mixed solution mixed with an acrylic monomer, a photo initiator, a cross-linking agent, methanol, and distilled water into a lower mold, combining an upper mold, and irradiating under UV of 5~40 W and 300~400 nm for 1~4 hours and performing photo-polymerization; and ii) a step of manufacturing the support unit in a joint state with the optical unit by injecting a mixed solution mixed with an acrylic monomer, distilled water, dimethylformamide, a cross-linking agent, a thermal initiator, and N,N,N',N'-tetramethyl ethylene diamine into the lower mold in which the optical unit is formed, and performing thermal polymerization at 30~100℃ for 30 minutes~2 hours.

17. The production method according to claim 16, characterized by, Said step ii) is performed continuously without separating said upper mold and said lower mold. ii) continuously performing a step of cooling said upper mold and said lower mold, without separating said upper mold and said lower mold.

Images