Eyeball sclera external implantation hydrogel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polymer biomedical materials, and particularly relates to an eyeball sclera external implantation hydrogel as well as a preparation method and application thereof. The invention provides a self-expandable hydrogel which is prepared by using methyl methacrylate, N-vinyl pyrrolidone and methacryloyloxyethyl trimethyl ammonium chloride as monomer raw materials through cross-linking of N, N-bis (acryloyl) cystamine, and the hydrogel is used for a rabbit pore-derived retinal detachment model. According to the material, the operation time is greatly shortened, the operation difficulty is reduced, meanwhile, the purposes of minimally invasive implantation, self-expansion, no need of suture and retina restoration are achieved, the material has good histocompatibility, and the material fills the technical blank of sclera buckle belt materials in hole-derived retina detachment treatment and has good application prospects. A novel diagnosis and treatment material which is safe, reliable and high in adaptability is provided for clinic, and a new solution is injected for precise treatment of related diseases.

Description

Technical Field

[0001] This invention belongs to the field of polymer biomedical materials technology, and specifically relates to an extrascleral implantable hydrogel for the eyeball, its preparation method and application. Background Technology

[0002] Rhegmatogenous retinal detachment is an ophthalmic emergency caused by the separation of the neuroepithelial layer of the retina from the underlying pigment epithelium, leading to the retina detaching from its normal position. This separation usually results from a tear or rupture in the retina, allowing vitreous fluid to enter the subretinal space, thus triggering detachment. If rhegmatogenous retinal detachment is not diagnosed and treated promptly, it can lead to retinal cell hypoxia and interruption of nutrient supply, causing irreversible vision damage, and in severe cases, even eyeball atrophy and permanent blindness.

[0003] Currently, the main surgical procedures for rhegmatogenous retinal detachment include pneumatic retinostomy, pars plana vitrectomy, scleral buckling, and pars plana vitrectomy combined with scleral buckling. Among these, scleral buckling is a classic and important surgical technique for treating rhegmatogenous retinal detachment. This procedure involves placing a ring-shaped silicone band or segmental silicone block on the outer surface of the sclera to generate pressure within the eyeball, bringing the retinal pigment epithelium and the detached retinal neuroepithelium closer together. Simultaneously, it relieves the traction of the vitreous on the retinal tear. Combined with retinal cryotherapy or laser treatment, this ultimately promotes the closure of the tear, creating conditions for successful retinal reattachment.

[0004] As an external ocular surgery, scleral buckling has unique advantages over vitrectomy, and is therefore considered an ideal choice for patients with rhegmatogenous retinal detachment, especially for young patients with phakic eyes, atrophic retinal tears, and low vitreous liquefaction. The success rate of the first surgery can exceed 80%.

[0005] Despite its significant advantages, scleral buckling surgery also faces numerous challenges, particularly the risk that prolonged presence of the buckling material increases the risk of postoperative refractive changes or diplopia. Furthermore, the buckling materials currently used for scleral buckling and segmental compression are mostly silicone and silicone sponge, which are essentially foreign bodies with poor tissue compatibility, making them highly susceptible to infection, material intrusion, or exposure. In addition, these compression materials are not easily degraded and can persist, causing irreversible changes in refractive status.

[0006] To address the aforementioned issues, there is an urgent need for a novel scleral buckling compression material that is minimally invasive, sutureless, self-expanding, capable of pressing and repositioning the retina, and possesses good tissue compatibility in the scleral buckling surgery selected for the treatment of rhegmatogenous retinal detachment. Summary of the Invention

[0007] To address the above-mentioned technical problems, this invention proposes an extrascleral implantable hydrogel for the eyeball, its preparation method, and its application.

[0008] The extrascleral implant hydrogel provided by this invention can be implanted into the target location outside the sclera through a conjunctival incision (about 5 mm). It does not require sutures and can slowly expand on its own, reaching its maximum expansion volume in 48 hours. It presses against the sclera to promote retinal repositioning. It begins to slowly degrade in about 8 to 10 weeks and is completely degraded in 12 to 16 weeks. It is well compatible with the tissues of the eyeball.

[0009] The technical solution of this invention is: This invention proposes an extrascleral implantable hydrogel, the structural formula of which is shown below: .

[0010] The present invention also provides a method for preparing a hydrogel having the above-described structure, comprising the following steps: (1) A mixture of methyl methacrylate (MMA), methacryloyloxyethyltrimethylammonium chloride and N-vinylpyrrolidone (PVP) in a volume ratio of 1:(1~5):(1~4) was used as the monomer raw material. Ultrapure water was added and mixed evenly. The volume ratio of ultrapure water to methyl methacrylate was 1~2:1. (2) Add a disulfide bond-containing bisacryloyl compound as a crosslinking agent and an azo compound as an initiator to the mixture system of (1), sonicate until transparent and uniform, fill with nitrogen, seal and store, and react at 80~100℃ for 12~24h to obtain the product. The disulfide-containing bisacryloyl compounds are selected from any one of N,N-bis(acryloyl)cystamine (BCA), N,N'-methylenebisacrylamide (MBA), and bis(2-acryloyloxyethyl) disulfide; The azo compounds are selected from any one of 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobisisobutyronitrile, 2,2'-azo (2-methylpropionamide) dihydrochloride, and azobisisobutyramidine hydrochloride; The mass ratio of the crosslinking agent to the initiator is 1:1 to 1.2, and the molar ratio of the methyl methacrylate to the crosslinking agent is 1:18 to 25.

[0011] In this invention, bisacryloyl compounds with disulfide bonds are used as crosslinking agents, preferably N,N-bis(acryloyl)cystamine. On the one hand, it can covalently crosslink with the double bond monomer through free radical polymerization to make the material more stable. On the other hand, the disulfide bonds of the crosslinking agent itself can give the hydrogel material better tensile properties.

[0012] The initiator used in this invention serves to provide initiation conditions for free radical polymerization. Therefore, any initiator that can achieve free radical binding is acceptable. However, some initiators may pose biological residue hazards. Therefore, 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide) is preferred as the initiator for crosslinking reaction in this invention. It can not only degrade at high temperatures but also has higher biological safety. In the hydrogel preparation method provided by this invention, preferably, the volume ratio of methyl methacrylate: methacryloyloxyethyltrimethylammonium chloride: N-vinylpyrrolidone in (1) is 1:(2~4):(2~4).

[0013] Preferably, the molar ratio of methyl methacrylate to crosslinking agent in (2) is 1:20~22.

[0014] As a preferred option, (2) is reacted at 90~95℃ for 12~16h.

[0015] Preferably, the method for preparing an extrascleral implantable hydrogel provided by the present invention includes the following steps: (1) A mixture of methyl methacrylate, methacryloyloxyethyltrimethylammonium chloride and N-vinylpyrrolidone in a volume ratio of 1:(1~5):(1~4) was used as the monomer raw material. Ultrapure water was added and mixed evenly. The volume ratio of ultrapure water to methyl methacrylate was 1~2:1. (2) Add N,N-bis(acryloyl)cysteine ​​as a crosslinking agent and 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide) as an initiator to the mixture in (1), sonicate until transparent and uniform, fill with nitrogen, seal and store, and react at 80~100℃ for 12~24h to obtain the product; wherein, the molar ratio of methyl methacrylate to crosslinking agent is 1:20~22. Furthermore, the application of the above hydrogel in the preparation of ophthalmic or medical materials, including extrascleral implant materials, is also a key technical content protected by this invention.

[0016] The beneficial effects of this invention are as follows: This invention provides a self-expanding hydrogel obtained by crosslinking methyl methacrylate, N-vinylpyrrolidone, and methacryloyloxyethyltrimethylammonium chloride with N,N-bis(acryloyl)cysteine. This hydrogel can continuously expand within 48 hours, with a maximum swelling capacity of approximately 830%. When used in a rabbit model of retinal detachment of rhegmatogenous origin, it significantly shortens the operation time and reduces the difficulty of the operation, while achieving the goals of minimally invasive placement, self-expansion, no sutures required, and retinal repositioning. It also has good tissue compatibility and has the potential for further clinical translation. Attached Figure Description

[0017] Figure 1 The graph shows the change in swelling ratio over time for different formulations of hydrogels provided by this invention. Figure 2 The infrared spectrum of the hydrogel prepared in Example 1 of this invention; Figure 3 This is an X-ray photoelectron spectroscopy (XPS) analysis diagram of the hydrogel prepared in Example 1 of this invention; Figure 4 This is a diagram showing the swelling experiment results of the hydrogel prepared in Example 1 of the present invention; Figure 5 The figure shows the experimental results of fracture and compressive modulus of the hydrogel prepared in Example 1 of the present invention; Figure 6 This is an experiment on the rheological properties of the hydrogel prepared in Example 1 of the present invention; Figure 7 The water contact angle of the hydrogel prepared in Example 1 of this invention; Figure 8 This is a biocompatibility experiment of the hydrogel prepared in Example 1 of the present invention; Figure 9 This is a surgical procedure diagram of the hydrogel prepared in Example 1 of the present invention for use in rabbit eyes with rhegmatogenous retinal detachment; Figure 10 This demonstrates the effectiveness of the hydrogel prepared in Example 1 of the present invention in rabbit eyes with rhegmatogenous retinal detachment. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0019] Example 1 An extrascleral implantable hydrogel is prepared using the following method: At room temperature, 200 μL of methyl methacrylate, 600 μL of methacryloyloxyethyltrimethylammonium chloride, and 600 μL of N-vinylpyrrolidone were added to a 5 mL glass bottle, followed by 200 μL of ultrapure water. The mixture was then stirred, and 1.6 mg of crosslinking agent N,N-bis(acryloyl)cysteine ​​and 1.6 mg of initiator 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide) were added. The mixture was sonicated for 30 seconds until it became transparent and homogeneous. Nitrogen gas was introduced, and the mixture was sealed and stored in an oven at 93°C overnight for 12 h to obtain an extrascleral implant hydrogel.

[0020] Comparative Example 1 A hydrogel, prepared differently from that in Example 1, uses sodium 2-acrylamido-2-methylpropylsulfonate as a monomer and N,N'-methylenebisacrylamide as a crosslinking agent. The specific preparation method is as follows: At room temperature, 200 μL of sodium 2-acrylamido-2-methylpropylsulfonate was added to a 5 mL glass bottle, followed by 200 μL of ultrapure water. The mixture was then stirred until clear and uniform. Nitrogen gas was introduced, the bottle was sealed, and the mixture was placed in an oven and reacted overnight at 93 °C for 12 h.

[0021] Comparative Example 2 A hydrogel, prepared differently from that in Example 1, uses sodium 2-acrylamido-2-methylpropylsulfonate as a monomer and N,N'-bis(acryloyl)cysteine ​​as a crosslinking agent. The specific preparation method is as follows: At room temperature, 200 μL of sodium 2-acrylamido-2-methylpropylsulfonate was added to a 5 mL glass bottle, followed by 200 μL of ultrapure water. The mixture was then stirred until clear and uniform. Nitrogen gas was introduced, the bottle was sealed, and the mixture was placed in an oven at 93 °C overnight for 12 h.

[0022] Swelling rate is a key indicator related to the performance of hydrogels. Therefore, in this invention, the swelling rate of hydrogels obtained from three different formulations in Example 1 and Comparative Examples 1-2 was measured. The swelling rates of hydrogels with different formulations are shown below. Figure 1 As shown.

[0023] As shown in the figure, the hydrogels prepared by the formulations of Comparative Example 1 and Comparative Example 2 swelled very quickly, reaching a plateau within 7 hours. In addition, the swelling rate of the hydrogels was at a low level, such as the final swelling rate of the hydrogel of Comparative Example 1 being only 260%, and the swelling rate of the hydrogel of Comparative Example 2 being 490%.

[0024] The reason for the above phenomenon may be that the hydrogel of Comparative Example 1 uses MBA as a crosslinking agent to polymerize with the hydrophilic monomer sodium 2-acrylamido-2-methylpropanesulfonate. Its strong crosslinking effect promotes the polymerization reaction and forms a dense network. In the hydrogel of Comparative Example 2, although the hydrophilic monomer remains unchanged, the crosslinking agent is replaced with BCA containing dynamic disulfide bonds. As a covalent crosslinking agent, MBA provides a strong bond to the network, while the dynamic disulfide bonds in BCA can break during deformation, thus achieving a high proportion of shape change.

[0025] In contrast, in Example 1, methacryloyloxyethyltrimethylammonium chloride (DMC) and N-vinylpyrrolidone (PVP) were used as swelling agents, and methyl methacrylate (MMA) was introduced to enhance the molecular network. N,N'-bis(acryloyl)cysteine ​​(BCA) was used as a crosslinking agent. The resulting hydrogel, although swelling at a slower rate, continued to expand within 48 hours, achieving a maximum swelling capacity of approximately 830%. This capacity is a result of the combined effects of the water-absorbing groups of DMC and PVP, the reinforcing effect of MMA, and the dynamic crosslinking effect of BCA.

[0026] In summary, the hydrogel prepared by the formulation in Example 1 exhibited excellent swelling ratio and compressive strength, which best met the key requirements of this study, and was therefore selected as the subject of subsequent research.

[0027] Experimental Example 1 This experimental example focuses on the structural characterization and performance verification of the hydrogel prepared in Example 1 of the present invention.

[0028] Figure 2 , Figure 3 The infrared spectrum and X-ray photoelectron spectroscopy (XPS) spectrum of the hydrogel prepared in Example 1 are shown respectively. The results in the figure show that quaternary ammonium groups, ester groups and amide groups were detected in the hydrogel. Combined with the infrared results, it is confirmed that the hydrogel was successfully synthesized.

[0029] The structure of the hydrogel prepared in Example 1 is shown in the following formula: .

[0030] Figure 4 The swelling test results of the hydrogel prepared in Example 1 are shown below. The swelling measurement method of the hydrogel is as follows: the hydrogel sample is weighed, then immersed in an excess of simulated body fluid, and then incubated in a 37°C water bath. The sample is taken out every 2 hours, the surface liquid is absorbed, and the sample is weighed again. The weight change is statistically analyzed.

[0031] Figure 4 The results show that the hydrogel obtained in Example 1 reached a maximum expansion factor of approximately 8.3 times within 24 hours.

[0032] Figure 5 The figure shows the fracture and compressive modulus test results of the hydrogel prepared in Example 1. The results show that compared with before expansion, the fracture strength of the material decreased significantly after expansion, while the compressive modulus remained basically unchanged.

[0033] Figure 6 The figure shows the rheological properties of the hydrogel prepared in Example 1. As can be seen from the figure, the hydrogel before expansion exhibits greater elasticity than viscosity, while the hydrogel material after expansion exhibits greater viscosity than elasticity.

[0034] Figure 7 The water contact angle of the hydrogel prepared in Example 1 is shown. The results show that the hydrogel material before expansion is hydrophilic, and the hydrogel material after expansion is hydrophobic.

[0035] Figure 8 The biocompatibility test results of the hydrogel prepared in Example 1 include live / dead cell staining, CCK-8 assay, and hemolysis assay. Among them, (A), (B), (C), and (D) are representative fluorescence microscopy images of live / dead cell analysis, quantification of survival rate based on live / dead cell analysis, cell viability detection by CCK-8 assay, and hemolysis assay results, respectively.

[0036] The results in the figure show that most cells in the hydrogel group survived well, indicating that the hydrogel has good cell compatibility. Figure 8 (A)); Quantitative analysis further confirmed these observations, with the proportion of viable cells exceeding 95% ( Figure 8 (B)); In addition, the CCK-8 assay showed that cell viability did not decrease significantly in any of the treatment groups ( Figure 8 In the middle (C) group, the survival rate was higher than 90%; Figure 8 The results (D) show that the average hemolysis rate of the hydrogel is 2.51%, which is far below the international standard of 5%, confirming its blood compatibility.

[0037] In summary, these results indicate that the hydrogel is non-toxic, does not impair cell viability or proliferation, and exhibits excellent in vitro biocompatibility.

[0038] Figure 9 The diagram shows the surgical procedure of using the hydrogel prepared in Example 1 for rhegmatogenous retinal detachment in rabbit eyes. As can be seen from the diagram, it is only necessary to cut open the conjunctiva of the eyeball and implant the hydrogel into the sclera of the target site. No sutures are required for the hydrogel, which achieves minimally invasive implantation and avoids suture-related complications.

[0039] Figure 10 The images show the application effect of the hydrogel prepared in Example 1 in rabbit eyes with rhegmatogenous retinal detachment. Among them, (A) is an anterior segment photograph, in which the hydrogel group shows no obvious inflammation or rejection reaction; (B) is a scanning laser fundus photograph, in which the retina in the hydrogel group is repositioned and there is no obvious adverse reaction in the eye; (C) is an ophthalmic B-scan ultrasound, in which the hydrogel can be seen pressing the sclera into the eye and promoting retinal repositioning; (D) is an optical coherence tomography scan, in which the results show that the retina in the hydrogel group is completely repositioned 1 week after surgery.

[0040] The above experiments and results demonstrate that this invention, through optimizing the monomer raw materials and crosslinking agent system for hydrogel preparation, has successfully developed a self-swelling hydrogel material with both excellent swelling properties and superior tissue compatibility. This material fills the technological gap in scleral buckling materials for the treatment of rhegmatogenous retinal detachment, providing clinicians with a safe, reliable, and highly adaptable new diagnostic and therapeutic material option, and injecting new solutions into the precision treatment of related diseases.

[0041] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. All equivalent changes and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An extrascleral implantable hydrogel, characterized in that, The structural formula of the hydrogel is shown below: 。 2. The method for preparing an extrascleral implantable hydrogel as described in claim 1, characterized in that, The steps include the following: (1) A mixture of methyl methacrylate, methacryloyloxyethyltrimethylammonium chloride and N-vinylpyrrolidone in a volume ratio of 1:(1~5):(1~4) was used as the monomer raw material. Ultrapure water was added and mixed evenly. The volume ratio of ultrapure water to methyl methacrylate was 1~2:

1. (2) Add a disulfide bond-containing bisacryloyl compound as a crosslinking agent and an azo compound as an initiator to the mixture system of (1), sonicate until transparent and uniform, fill with nitrogen, seal and store, and react at 80~100℃ for 12~24h to obtain the product. The disulfide-containing bisacryloyl compounds are selected from any one of N,N-bis(acryloyl)cystamine, N,N'-methylenebisacrylamide, and bis(2-acryloyloxyethyl) disulfide; The azo compounds are selected from any one of 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobisisobutyronitrile, 2,2'-azo (2-methylpropionamide) dihydrochloride, and azobisisobutyramidine hydrochloride; The mass ratio of the crosslinking agent to the initiator is 1:1 to 1.2, and the molar ratio of the methyl methacrylate to the crosslinking agent is 1:18 to 25.

3. The preparation method according to claim 2, characterized in that, The volume ratio of methyl methacrylate, methacryloyloxyethyltrimethylammonium chloride, and N-vinylpyrrolidone described in (1) is 1:(2~4):(2~4).

4. The preparation method according to claim 2, characterized in that, (2) The crosslinking agent is N,N-bis(acryloyl)cysteamine, and the initiator is 2,2-azo (2-methyl-N-(2-hydroxyethyl)propionamide).

5. The preparation method according to claim 2, characterized in that, (2) The molar ratio of methyl methacrylate to crosslinking agent is 1:20~22.

6. The preparation method according to claim 2, characterized in that, (2) React at 90~95℃ for 12~16h.

7. The use of the hydrogel as described in claim 1 or the hydrogel prepared by any one of claims 2 to 6 in the preparation of extrascleral implant materials for the eye.

Images