A posterior scleral reinforcement material and method of making the same

Abstract

This invention relates to the field of biomedical polymer materials and surface modification engineering, specifically to a posterior scleral reinforcement material and its preparation method. It comprises a polymer matrix and a bioactive modified layer formed by the oxidative crosslinking of a heterobifunctional polymer coupling compound. This copolymer structure includes anchoring groups, hydrophilic linkers, and bioactive groups. Its core principle is to utilize the flexible extension of the hydrophilic linkers to reduce steric hindrance, fully exposing the bioactive groups to the material surface, thereby achieving efficient recognition and binding to integrin receptors. This invention effectively solves the problems of bioinertness of the synthesized polymer matrix and lack of cell recognition sites, achieving a cell proliferation rate more than twice that of the unmodified matrix, demonstrating the material's excellent bioactivity and cell compatibility.

Description

Technical Field

[0001] This invention relates to the field of biomedical polymer materials and surface modification engineering, specifically to a posterior scleral reinforcement material and its preparation method. Background Technology

[0002] In current applications of posterior scleral reinforcement in the treatment of pathological myopia, synthetic polymer materials such as polycaprolactone, polylactic acid-glycolic acid copolymer, or polyurethane are often selected as the matrix to prepare nanofiber membranes with specific pore structures.

[0003] To improve the surface properties of such synthetic materials, existing methods generally employ simple physical adsorption or single dopamine oxidative polymerization for surface modification. While this approach can improve the hydrophilicity of the material to some extent, the inherent biological inertness of the polymer matrix and the lack of specific cell recognition sites, coupled with the weak adhesion of the uncrosslinked and uncured coating under physiological conditions, result in limited improvement in cell adhesion and proliferation efficiency. Furthermore, the modified layer is prone to dissociation and detachment during long-term in vivo use, making it difficult to achieve lasting biological effects and effective integration with autologous tissues. Therefore, overcoming the biological inertness of the synthetic polymer matrix and constructing a biomimetic modified interface that combines excellent hydrophilicity, specific biological activity, and long-term structural stability has become an urgent technical problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a posterior scleral reinforcement material and its preparation method to solve the problems mentioned in the background art. Specifically, the technical solution of this invention is as follows: The reinforcing material includes a polymer matrix and a bioactive modified layer deposited on the surface of the polymer matrix; The bioactive modified layer is formed by oxidative self-polymerization and cross-linking curing of a functionalized modifier; the functionalized modifier is a heterobifunctional polymer conjugate, the structure of which includes an anchoring group, a hydrophilic linker arm and a bioactive group.

[0005] Preferably, the polymer matrix is ​​an electrospun nanofiber membrane with a fiber diameter of 200-800 nm and a porosity of 60%-90%. The polymer matrix material is selected from one or more blends of polycaprolactone, polylactic acid-hydroxyacetic acid copolymer, polyethylene terephthalate, or polyurethane.

[0006] Preferably, the anchoring group of the functionalized modifier is dopamine or catechol derivative; the hydrophilic linker is polyethylene glycol with a molecular weight of 1000-10000 Da; and the bioactive group is RGD polypeptide, preferably GRGDSPK peptide. The water contact angle of the surface of the reinforcing material is 30°-40°, and the N / C ratio in the surface elemental analysis is 0.10-0.15.

[0007] Preferably, the elastic modulus of the reinforcing material is 3-15 MPa, and the bioactive modified layer has an intermolecular cross-linking network induced by genipin or an oxidant.

[0008] Preferably, the cell proliferation rate of human scleral fibroblasts inoculated on the surface of the reinforcing material and cultured for 3 days reaches more than 200% of that of the unmodified polymer matrix.

[0009] A method for preparing a posterior scleral reinforcement material includes the following steps: Step S1: Synthesize functionalized modifiers. After activating bi-terminal carboxyl polyethylene glycol, anchoring groups and RGD peptides are grafted onto it. After dialysis purification and freeze-drying, powdered functionalized modifiers are obtained. Step S2: Prepare a polymer matrix, prepare a nanofiber membrane by electrospinning, and perform plasma cleaning pretreatment; Step S3: Biomimetic interface modification, prepare a weak alkaline buffer solution to dissolve the functionalized modifier, completely immerse the pretreated polymer matrix in the solution, and carry out the reaction under light-proof and constant temperature oscillation conditions to induce the oxidative self-polymerization deposition of anchoring groups; Step S4: Crosslinking, curing and cleaning. The modified substrate is ultrasonically cleaned at a power of 100-200W and a frequency of 40-60kHz for 3-5 minutes per cleaning cycle. Then, it is immersed in a crosslinking agent solution for secondary crosslinking. Finally, it is rinsed with deionized water and vacuum dried to obtain the postscleral reinforcement material.

[0010] Preferably, the specific operation of synthesizing the functionalized modifier in step S1 is as follows: Biscarboxyl-terminated polyethylene glycol with a molecular weight of 3000-4000 Da was dissolved in anhydrous dimethyl sulfoxide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to activate the carboxyl groups for 0.5-2 hours. A dimethyl sulfoxide solution of dopamine hydrochloride was added dropwise to the solution, and the molar ratio of polyethylene glycol to dopamine was controlled at 1:(0.6-0.9). Triethylamine was added to adjust the apparent pH to 7.0-8.0. The reaction was carried out under strict anaerobic and light-protected conditions at 20-25℃ for 20-30 hours. The reaction product was separated by ion exchange chromatography to remove the bi-terminal modified byproducts and unreacted monomers, and then purified. The dialysate was changed every 6-8 hours during dialysis, and the temperature was controlled at 4℃. The intermediate was obtained by freeze drying. The intermediate was dissolved in PBS buffer, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to reactivate the remaining carboxyl group. Then, the GRGDSPK peptide with lysine at the end was added. The reaction was carried out at 20-25°C for 20-30 hours. The reaction product was separated by ion exchange chromatography to remove the bi-terminal modification byproducts and unreacted monomers. The product was then purified for 3-5 days. During dialysis, the dialysis solution was changed every 6-8 hours, and the temperature was controlled at 4°C. The functionalized modifier was obtained by freeze drying.

[0011] Preferably, the parameters of the electrospinning process in step S2 are controlled as follows: the polymer is dissolved in hexafluoroisopropanol to prepare a spinning solution with a mass-volume ratio of 10%-15%, the spinning voltage is 12-18kV, the receiving distance is 12-18cm, and the injection speed is 0.8-1.2mL / h. The power of the plasma cleaning pretreatment is 80-120W, and the treatment time is 40-80s.

[0012] Preferably, in step S3, the weakly alkaline buffer solution is a Tris-HCl buffer solution with a concentration of 5-15 mM and a pH value of 8.0-9.0; The concentration of the functionalized modifier in the buffer solution is 1-3 mg / mL; the temperature of the isothermal oscillation reaction is 35-40℃, and the reaction time is 10-14 h.

[0013] Preferably, in step S4, the ultrasonic cleaning is performed by repeatedly cleaning with deionized water 3-5 times under the conditions of power 100-200W and frequency 40-60kHz, with each cleaning lasting 3-5 minutes. The crosslinking agent solution is a genipin solution with a concentration of 0.05%-0.2% (w / v), and the secondary crosslinking time is 3-5 hours. After the vacuum drying step, the obtained postscleral reinforcement material is subjected to an ethylene oxide sterilization step.

[0014] Compared with the prior art, the present invention has the following improvements and advantages: 1. This invention effectively solves the problems of bioinertness and lack of cell recognition sites on the surface of synthetic polymer matrices. By constructing a heterobifunctional polymer conjugate containing anchoring groups, hydrophilic linkers, and bioactive groups as a modifier, the steric hindrance is effectively reduced by utilizing the flexible extension of the hydrophilic linkers, and the bioactive groups are fully exposed on the material surface, achieving efficient recognition and binding of cell integrin receptors. Experimental data show that after three days of culture with human scleral fibroblasts, the cell proliferation rate on the surface of the material of this invention reaches more than 200% of that of the unmodified matrix, confirming its excellent bioactivity and cell compatibility. 2. This invention significantly improves the long-term stability of the bioactive modified layer under physiological conditions, overcoming the shortcomings of existing coating technologies such as weak adhesion and easy dissociation and detachment. By introducing the natural crosslinking agent genipin, secondary crosslinking is performed on the basis of the anchoring group oxidative self-polymerization deposition, inducing the formation of a dense intermolecular crosslinking network inside the modified layer, transforming physical adsorption into a strong chemical bond; stability tests show that after long-term immersion in physiological buffer solution, the coating loss rate on the surface of the material of this invention is controlled within 5%, while the loss rate of the control group lacking secondary crosslinking is as high as 40% or more, thus ensuring the lasting efficacy of the posterior scleral reinforcement material during long-term in vivo service; 3. The reinforcement material prepared by this invention has an ideal hydrophilic interface and biomimetic structure, which improves the tissue integration ability after implantation. The nanofiber membrane prepared by electrospinning technology has high porosity and simulates the topological structure of the natural extracellular matrix. Combined with the hydration layer introduced by the hydrophilic linker arm, it significantly improves the surface wettability of the hydrophobic polymer matrix and stably reduces the water contact angle of the material surface to between 30° and 40°. This synergistic effect of high hydrophilicity and nanoporous structure not only facilitates the permeation and transport of nutrients, but also reduces the risk of inflammatory response after implantation by inhibiting the adsorption of non-specific proteins. 4. This invention achieves controllable adjustment of the mechanical properties of posterior scleral reinforcement materials, meeting the needs of different clinical scenarios. By selecting polymer matrices with different mechanical properties, such as polycaprolactone and polyurethane, and by controlling the concentration of crosslinking agents and reaction conditions within the modified layer, reinforcement materials with an elastic modulus in the range of 3-15 MPa can be obtained. This mechanical range matches the natural scleral tissue, providing sufficient mechanical support to prevent further elongation of the axial length of the eye, while also possessing good flexibility to avoid stress shielding or mechanical damage to the eyeball tissue caused by excessively hard materials. At the same time, the natural crosslinking agents used have higher biocompatibility compared to chemical crosslinking agents. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0016] Before formal preparation, this invention pre-established an oxidative self-polymerization kinetic model of the functionalized modifier in a buffer system to determine the optimal pH and temperature control points in step S3. The specific method for establishing the model is as follows: the functionalized modifier is dissolved in Tris-HCl buffer solutions with different pH values ​​(7.5-9.5) and temperatures (25-45℃), and the change in absorbance at 420nm is monitored in real time using a UV-Vis spectrophotometer to characterize the degree of oxidation of the dopamine group. Regression analysis data shows that the oxidative self-polymerization rate constant k exhibits a significant nonlinear positive correlation with pH and temperature T, with a Pearson correlation coefficient r = 0.92. Specifically, when pH < 8.0 or T < 30℃, the polymerization reaction is in the induction phase, and the film formation rate is extremely slow, making it difficult to form a continuous coating layer. When pH > 9.0 or T > 40℃, the reaction rate is too fast, leading to homogeneous nucleation dominating in the solution and easily producing large particle precipitates rather than surface deposition. Only within the steady-state window of pH 8.0-9.0 and T = 35-40℃, heterogeneous nucleation and surface growth mechanisms work synergistically to induce the formation of a dense, uniform, and controllable thickness bioactive modified layer. Based on this model, this invention sets pH 8.0-9.0 and 35-40℃ as the key process parameters for inducing the oxidative self-polymerization deposition of anchoring groups.

[0017] Example 1: This embodiment provides a complete posterior scleral reinforcement material and its preparation method, with the specific steps as follows: Step S1: Synthesize functionalized modifiers Bis-terminated carboxyl polyethylene glycol with a molecular weight of 3000 Da was selected as the precursor for the hydrophilic linker. This molecular weight range was chosen to construct a flexible barrier with moderate steric hindrance, which can effectively shield the hydrophobicity of the substrate without burying the bioactive groups at the end due to excessive chain length. The polyethylene glycol was dissolved in anhydrous dimethyl sulfoxide, activated with an activator for 0.5 h, and the molar ratio of polyethylene glycol to dopamine was controlled at 1:0.6. Triethylamine was added to adjust the pH to 8.0, and the reaction was carried out under strict nitrogen protection and anhydrous conditions at 20°C for 20 h. The reaction product was separated by ion exchange chromatography to remove the bi-terminal modification byproducts and unreacted monomers, and then purified. The dialysate was changed every 6 hours to remove unreacted small molecule monomers and some ungrafted polyethylene glycol to prevent them from interfering with the subsequent self-assembly process. The key raw material GRGDSPK peptide used in this step was prepared using the standard Fmoc solid-phase synthesis method: Fmoc-Pro-WangResin was used as the solid-phase carrier, and Fmoc-protected Lys, Ser, Asp, Gly, Arg, and Gly amino acids were sequentially added. After lysis, precipitation, and HPLC purification, the purity was controlled to be above 98%. The obtained intermediate was dissolved in PBS buffer, the remaining carboxyl groups were reactivated, and then the GRGDSPK peptide was added. The reaction was carried out at 20°C for 20 h, purified by dialysis for 3 days, and freeze-dried to obtain a powdered functionalized modifier.

[0018] Step S2: Preparation of polymer matrix Polycaprolactone was selected as the raw material and dissolved in hexafluoroisopropanol to prepare a spinning solution with a mass-to-volume ratio of 10%. The electrospinning voltage was set at 12kV, the receiving distance at 12cm, and the injection speed at 0.8mL / h. This combination of low concentration and low injection speed facilitated the rapid evaporation of the solvent, forming a nanofiber membrane with a fine fiber diameter and high porosity. This topological structure highly simulates the natural extracellular matrix, providing ideal physical support for the extension of pseudopodia in cells. Subsequently, a plasma cleaning pretreatment was performed at 80W for 40s. This step introduced initial active sites such as hydroxyl and carboxyl groups on the fiber surface through high-energy particle bombardment, significantly reducing the surface energy and laying the interfacial foundation for the wetting and anchoring of subsequent functional modifiers.

[0019] Step S3: Biomimetic Interface Modification A 5 mM Tris-HCl buffer solution with a pH of 8.0 was prepared, and the functionalized modifier was dissolved in it at a concentration of 1 mg / mL. The pretreated polymer matrix was then immersed in the buffer solution, and the reaction was carried out at 35°C and 60 rpm for 10 h with constant temperature shaking. The weakly alkaline environment and moderate stirring triggered the oxidative self-polymerization kinetics of the anchoring group dopamine, allowing the functionalized modifier to form a uniform deposition layer on the matrix surface in situ through non-covalent and covalent bonds. The water contact angle of the modified material surface was reduced to 30°, and the N / C ratio of the surface elemental analysis was 0.10, indicating that the hydrophilic PEG segments and nitrogen-rich RGD peptide segments had successfully covered the hydrophobic matrix. The modified material surface in this step was preliminarily covered with a coating layer containing hydrophilic PEG segments and RGD peptide segments.

[0020] Step S4: Crosslinking Curing and Cleaning The coating was ultrasonically cleaned three times at a power of 100W and a frequency of 40kHz, each time for 3 minutes, to remove loosely adsorbed molecules using cavitation effect and prevent uncontrolled peeling during use. It was then immersed in a 0.05% (w / v) genipin solution for secondary crosslinking for 3 hours. Genipin, as a natural crosslinking agent, mainly reacts with the ε-amino group of the lysine terminal of the bioactive group RGD peptide, inducing the formation of a dense intermolecular crosslinking network within the bioactive modified layer. The degree of crosslinking was controlled to retain sufficient bioactive sites. After cleaning, vacuum drying, and ethylene oxide sterilization, the final posterior scleral reinforcement material was obtained.

[0021] Performance testing: Testing revealed that the posterior scleral reinforcement material prepared in this embodiment had a water contact angle of 30.25°, an N / C ratio of 0.10, and an elastic modulus of 3.12 MPa. The cell proliferation rate of human scleral fibroblasts cultured for 3 days after inoculation was 205.40% higher than that of the unmodified matrix.

[0022] Example 2: This embodiment provides a posterior scleral reinforcement material and its preparation method, which is based on another parameter combination of the technical solution in Example 1. In this embodiment, the functionalized modifier is a bicarbonate-terminated polyethylene glycol with a molecular weight of 3400 Da. During the synthesis process, the molar ratio of polyethylene glycol to dopamine is controlled at 1:0.7, the pH is adjusted to 8.5, the reaction temperature is 22°C, and the reaction time is 24 hours. The dialysate is changed every 7 hours during dialysis. This medium molecular weight polyethylene glycol segment provides a good hydration layer, which helps resist non-specific protein adsorption, thereby reducing the risk of inflammatory response. In the preparation of the polymer matrix, polylactic acid-glycolic acid copolymer was selected as the raw material and a spinning solution of 12% was prepared. The electrospinning voltage was set to 15kV, the receiving distance to 15cm, and the injection speed to 1.0mL / h. The resulting polymer matrix was an electrospun nanofiber membrane with a fiber diameter of approximately 450nm and a porosity of approximately 75%. The plasma cleaning pretreatment power was 100W and the time was 60s to enhance the wettability of the matrix surface and facilitate the penetration of the subsequent modification solution. In the biomimetic interface modification, a functionalized modifier with a concentration of 2 mg / mL was dissolved in a 10 mM Tris-HCl buffer solution at pH 8.5. The reaction was carried out at 37 °C and 90 rpm for 12 h. These reaction conditions promoted the moderate oxidation and oligomerization of the anchoring group dopamine, and the bioactive modified layer was firmly anchored to the fiber surface through non-covalent interactions and covalent bonding. In the crosslinking curing and cleaning, the ultrasonic cleaning power was set to 150 W, the frequency to 50 kHz, and the cleaning time was 4 minutes per cycle. The secondary crosslinking was carried out using a 0.1% (w / v) genipin solution for 4 h. The crosslinking network constructed in this step significantly improved the tolerance of the bioactive modified layer under physiological conditions, ensuring that the bioactive group RGD peptide can be exposed to the surface for a long time to exert its function. This embodiment, by adjusting the matrix material and modification parameters, produces a material with a surface water contact angle of 35°, an N / C ratio of 0.12, an elastic modulus of 8 MPa, and a cell proliferation rate that is 230% higher than that of the unmodified matrix, demonstrating the universality of this method on different matrix materials.

[0023] Example 3: This embodiment provides a posterior scleral reinforcement material and its preparation method, which focuses on improving mechanical properties by enhancing the cross-linking network. In this embodiment, the functional modifier is synthesized using bi-terminated carboxyl polyethylene glycol with a molecular weight of 4000 Da. The longer hydrophilic segments aim to maximize the hydrophilic modification effect on the material surface. The molar ratio of polyethylene glycol to dopamine is controlled at 1:0.9, the pH is adjusted to 9.0, and the reaction is carried out at 25°C for 30 hours. The high dopamine grafting rate ensures a high-density coverage of the functional modifier on the matrix surface. In the preparation of the polymer matrix, polyurethane was selected as the raw material and a spinning solution of 15% was prepared; the spinning voltage was 18kV, the receiving distance was 18cm, and the injection speed was 1.2mL / h; the resulting polymer matrix had a fiber diameter of approximately 800nm ​​and a porosity of approximately 90%; the higher porosity is beneficial for the transport of nutrients; the plasma pretreatment power was 120W and the time was 80s; in the biomimetic interface modification, the buffer concentration was 15mM, pH 9.0, and the functionalized modifier concentration was 3mg / mL; the reaction was carried out at 40℃ and 120rpm for 14h; the higher pH value and temperature accelerated the oxidative self-polymerization kinetics, promoting the rapid formation of the bioactive modified layer and reaching a certain thickness, fully covering the matrix fibers; In the crosslinking curing and cleaning process, ultrasonic cleaning power was 200W, frequency 60kHz, and a single cleaning time of 5 minutes; secondary crosslinking used a 0.2% (w / v) genipin solution for 5 hours; the high concentration of 0.2% provided sufficient crosslinking active centers, increasing the degree of crosslinking to 88%. This high-density network structure is the decisive factor in achieving an elastic modulus of 15MPa; the enhanced crosslinking conditions endowed the reinforced material with excellent mechanical stability, enabling it to withstand the shear force generated by eye movement; the material obtained in this embodiment has a surface water contact angle of 40°, an N / C ratio of 0.15, an elastic modulus of 15MPa, and a cell proliferation rate that is 250% higher than that of the unmodified matrix, making it particularly suitable for posterior scleral reinforcement surgery scenarios with high mechanical strength requirements.

[0024] Example 4: This embodiment provides a posterior scleral reinforcement material and its preparation method, aiming to balance bioactivity and degradation rate. In this embodiment, the functional modifier is synthesized using polyethylene glycol with a molecular weight of 1000 Da. The reaction is controlled with a polyethylene glycol to dopamine molar ratio of 1:0.8, pH 8.2, and a reaction time of 22 h at 23°C. This ratio aims to balance anchoring stability and exposure efficiency of bioactive sites. In the preparation of the polymer matrix, a blend of polycaprolactone and polylactic acid-glycolic acid copolymer was selected, with a spinning solution concentration of 11%; voltage of 14 kV, distance of 14 cm, and speed of 0.9 mL / h; the resulting polymer matrix possesses both mechanical and degradation properties of the two materials; plasma treatment was performed at 90 W for 50 s; in the biomimetic interface modification, the buffer solution pH was 8.2, and the functionalizing modifier concentration was 1.5 mg / mL; the reaction was carried out at 36 °C and 80 rpm for 11 h; the mild reaction conditions helped control the uniformity of the bioactive modified layer and avoid particle accumulation caused by over-polymerization; In the crosslinking curing and cleaning process, the ultrasonic power was 120W and the frequency was 45kHz; the crosslinking agent concentration was 0.08% and the time was 3.5h; the appropriate crosslinking density provided necessary structural support while maintaining the flexibility of the bioactive modified layer; the material obtained in this embodiment had a surface water contact angle of 33°, an N / C ratio of 0.11, an elastic modulus of 6MPa, and a cell proliferation rate that was 215% higher than that of the unmodified matrix, demonstrating excellent comprehensive performance.

[0025] Example 5: This embodiment provides a posterior scleral reinforcement material and its preparation method, focusing on surface modification of a high-strength matrix. In this embodiment, the functional modifier is synthesized using polyethylene glycol with a molecular weight of 3800 Da; the molar ratio is 1:0.85, the pH is 8.8, and the reaction is carried out at 24°C for 28 hours. These parameters ensure a high conversion rate of the intermediate. In the preparation of the polymer matrix, polyethylene terephthalate was selected, with a spinning solution concentration of 14%; the voltage was 16 kV, the distance was 16 cm, and the speed was 1.1 mL / h; the resulting polymer matrix exhibited high mechanical strength; plasma treatment was performed at 110 W for 70 s; in the biomimetic interface modification, the buffer solution pH was 8.8, the functionalizing modifier concentration was 2.5 mg / mL, and the reaction was carried out at 38 °C and 100 rpm for 13 h; the higher modifier concentration facilitated full coverage on the surface of nanofibers with a large specific surface area; in the crosslinking curing and cleaning, the ultrasonic power was 180 W, the frequency was 55 kHz, the crosslinking agent concentration was 0.15%, and the time was 4.5 h; this step ensured that the functionalizing modifier would not dissociate in subsequent cell culture or in vivo environment; The material prepared in this embodiment has a water contact angle of 38°, an N / C ratio of 0.14, an elastic modulus of 12 MPa, and a cell proliferation rate that is 240% higher than that of the unmodified matrix, thus verifying the effectiveness of the modified system on inert polymer surfaces.

[0026] Comparative Example 1: This comparative example provides a postscleral reinforcement material without surface bioactivity modification; its preparation process only includes step S2 in Example 2, namely, preparing an electrospun nanofiber membrane of polylactic acid-glycolic acid copolymer, without plasma cleaning pretreatment, and without subsequent functionalization modification and cross-linking curing steps; this material lacks a bioactive modification layer, and the surface mainly exhibits the hydrophobic properties of the polymer matrix itself; this comparative example serves as a blank control to verify the fundamental contribution of the bioactive modification layer to the hydrophilicity and cell compatibility of the material.

[0027] Comparative Example 2: This comparative example provides a modified material lacking hydrophilic linker arms and specific bioactive groups; its preparation process is similar to that of Example 2, except that in step S1, only dopamine hydrochloride is directly dissolved in Tris-HCl buffer to coat the polymer matrix, without introducing polyethylene glycol linker arms and RGD peptides; this comparative example aims to verify the synergistic effect of each component in the triblock copolymer structure of the present invention, especially the antifouling function of the PEG linker arms and the active recognition function of the RGD peptides.

[0028] Comparative Example 3: This comparative example provides a post-scleral reinforcement material that has not undergone secondary cross-linking and curing; its preparation process is similar to that of Example 2, except that the genipin cross-linking step in step S4 is omitted, and only simple cleaning is performed; this comparative example aims to verify the influence of intermolecular cross-linking network on the stability of the bioactive modified layer and to reveal the difference between physical adsorption and chemical cross-linking in long-term service. To further verify the performance advantages of the posterior scleral reinforcement material of the present invention, the materials prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance comparison tests. Test items: Water contact angle: characterizes the hydrophilicity of the material surface; the smaller the angle, the better the hydrophilicity. Cell proliferation rate: Based on Comparative Example 1, after inoculating human scleral fibroblasts and culturing for 3 days, the relative proliferation rate of each group was determined by the CCK-8 method to characterize the cell compatibility and bioactivity of the material. Coating stability: The material was placed in PBS buffer at 37°C and shaken for 7 days to test the change rate of the surface N / C ratio before and after soaking.

[0029] Test Standards Water contact angle determination: The optical contact angle meter (Krüss DSA25) was used to measure the water contact angle at room temperature using the seated drop method. 2 μL of deionized water was added to the material surface, and the contact angle image was recorded within 5 seconds after the droplet contacted the surface. The average value was taken at 5 different locations for each sample. Surface elemental analysis: X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha) was used with AlKα rays as the excitation source to analyze the atomic percentage of N and C elements on the material surface and calculate the N / C ratio. Cell proliferation rate determination: In accordance with ISO10993-5 standard, human scleral fibroblasts were seeded on the material surface at a density of 5×10³ cells / well. After culturing for 3 days, CCK-8 reagent was added, and after incubation for 2 hours, the absorbance at 450 nm was measured using an ELISA reader, and the relative proliferation rate was calculated (n=6). Coating stability test: The sample was immersed in PBS buffer at pH 7.4 and placed in a constant temperature shaker (100 rpm) at 37℃ for 7 days. After removal, it was rinsed with deionized water, vacuum dried, and XPS analysis was performed again to calculate the rate of change of N / C ratio: rate of change = |(initial N / C - N / C after soaking) / initial N / C|×100%.

[0030] Table 1: Performance test results of each embodiment and comparative example

[0031] Note: " / " indicates that the test was not performed.

[0032] Analysis of the data in Table 1 shows that the posterior scleral reinforcement materials prepared in Examples 1-5 of this invention significantly improved the hydrophilicity of the material surface by introducing a functionalized modifier composed of anchoring groups, hydrophilic linkers, and bioactive groups. The contact angle was stabilized between 30° and 40°, and the cell proliferation rate was greatly increased. This indicates that the bioactive group RGD peptide effectively promoted cell adhesion and growth through the flexible display of hydrophilic linkers, achieving good integration between the material and the tissue.

[0033] Comparing Example 2 with Comparative Example 1, it can be seen that the unmodified matrix exhibits strong hydrophobicity and low cell proliferation rate, which makes it difficult to meet the biocompatibility requirements of the posterior scleral reinforcement material; while Example 2, through surface modification, successfully transformed the hydrophobic interface into a hydrophilic and bioactive interface. Comparing Example 2 with Comparative Example 2, it can be seen that although the use of polydopamine coating alone improves hydrophilicity, the increase in cell proliferation rate is limited and far lower than that of the embodiments of the present invention. This confirms the necessity of the PEG linker + RGD polypeptide structure: the PEG chain segment inhibits non-specific adsorption through the hydration layer, while the RGD polypeptide provides a specific cell recognition site. The synergistic effect of the two is significantly better than the improvement of physical adsorption alone.

[0034] Comparing Example 2 and Comparative Example 3, it can be seen that although the sample lacking the secondary crosslinking step has good physicochemical properties in the initial stage, its coating N / C ratio change rate is as high as 42.50% in the stability test, indicating that the coating lacking the crosslinking network is very easy to fall off under physiological conditions. In contrast, the embodiments of the present invention control the coating loss rate to within 5% through the intermolecular crosslinking network induced by genipin, ensuring the performance stability of the posterior scleral reinforcement material during long-term in vivo service. The present invention successfully obtained a posterior scleral reinforcement material with excellent bioactivity, suitable mechanical properties and long-term stability through specific molecular structure design and genipin crosslinking process.

[0035] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A posterior scleral reinforcement material, characterized by, The reinforcing material includes a polymer matrix and a bioactive modified layer deposited on the surface of the polymer matrix; The bioactive modified layer is formed by oxidative self-polymerization and cross-linking curing of a functionalized modifier; the functionalized modifier is a heterobifunctional polymer conjugate, the structure of which includes an anchoring group, a hydrophilic linker arm and a bioactive group.

2. The posterior scleral reinforcement material of claim 1, wherein, The polymer matrix is ​​an electrospun nanofiber membrane with a fiber diameter of 200-800 nm and a porosity of 60%-90%. The polymer matrix material is selected from one or more blends of polycaprolactone, polylactic acid-hydroxyacetic acid copolymer, polyethylene terephthalate, or polyurethane.

3. The posterior scleral reinforcement material of claim 1, wherein, The anchoring group of the functionalized modifier is dopamine or catechol derivative; the hydrophilic linker is polyethylene glycol with a molecular weight of 1000-10000 Da; and the bioactive group is RGD peptide. The water contact angle of the surface of the reinforcing material is 30°-40°, and the N / C ratio in the surface elemental analysis is 0.10-0.

15.

4. The posterior scleral reinforcement material of claim 1, wherein, The elastic modulus of the reinforcing material is 3-15 MPa, and the bioactive modified layer has an intermolecular cross-linking network induced by genipin or an oxidant.

5. The posterior scleral reinforcement material of claim 1, wherein, The cell proliferation rate of human scleral fibroblasts inoculated on the surface of the reinforcing material and cultured for 3 days reached more than 200% of that of the unmodified polymer matrix.

6. A method for preparing a posterior scleral reinforcement material, characterized in that, Includes the following steps: Step S1: Synthesize functionalized modifiers. After activating bi-terminal carboxyl polyethylene glycol, anchoring groups and RGD peptides are grafted onto it. After dialysis purification and freeze-drying, powdered functionalized modifiers are obtained. Step S2: Prepare a polymer matrix, prepare a nanofiber membrane by electrospinning, and perform plasma cleaning pretreatment; Step S3: Biomimetic interface modification, prepare a weak alkaline buffer solution to dissolve the functionalized modifier, completely immerse the pretreated polymer matrix in the solution, and carry out the reaction under light-proof and constant temperature oscillation conditions to induce the oxidative self-polymerization deposition of anchoring groups; Step S4: Crosslinking, curing and cleaning. The modified substrate is ultrasonically cleaned at a power of 100-200W and a frequency of 40-60kHz for 3-5 minutes per cleaning cycle. Then, it is immersed in a crosslinking agent solution for secondary crosslinking. Finally, it is rinsed with deionized water and vacuum dried to obtain the postscleral reinforcement material.

7. The method for preparing a posterior scleral reinforcement material according to claim 6, characterized in that, The specific steps for synthesizing the functionalized modifier in step S1 are as follows: Biscarboxyl-terminated polyethylene glycol with a molecular weight of 1000-4000 Da was dissolved in anhydrous dimethyl sulfoxide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to activate the carboxyl groups for 0.5-2 hours. A dimethyl sulfoxide solution of dopamine hydrochloride was added dropwise to the solution, and the molar ratio of polyethylene glycol to dopamine was controlled at 1:(0.6-0.9). Triethylamine was added to adjust the apparent pH to 7.0-8.

0. The reaction was carried out under strict anaerobic and light-protected conditions at 20-25℃ for 20-30 hours. The reaction product was separated by ion exchange chromatography to remove the bi-terminal modified byproducts and unreacted monomers, and then purified. The dialysate was changed every 6-8 hours during dialysis, and the temperature was controlled at 4℃. The intermediate was obtained by freeze drying. The intermediate was dissolved in PBS buffer, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to reactivate the remaining carboxyl group. Then, the GRGDSPK peptide with lysine at the end was added. The reaction was carried out at 20-25°C for 20-30 hours. The reaction product was separated by ion exchange chromatography to remove the bi-terminal modification byproducts and unreacted monomers. The product was then purified for 3-5 days. During dialysis, the dialysis solution was changed every 6-8 hours, and the temperature was controlled at 4°C. The functionalized modifier was obtained by freeze drying.

8. The method for preparing a posterior scleral reinforcement material according to claim 6, characterized in that, The parameters for the electrospinning process in step S2 are controlled as follows: the polymer is dissolved in hexafluoroisopropanol to prepare a spinning solution with a mass-volume ratio of 10%-15%; the spinning voltage is 12-18kV; the receiving distance is 12-18cm; and the injection speed is 0.8-1.2mL / h. The power of the plasma cleaning pretreatment is 80-120W, and the treatment time is 40-80s.

9. The method for preparing a posterior scleral reinforcement material according to claim 6, characterized in that, In step S3, the weakly alkaline buffer solution is a Tris-HCl buffer solution with a concentration of 5-15 mM and a pH value of 8.0-9.0; The concentration of the functionalized modifier in the buffer solution is 1-3 mg / mL; the temperature of the isothermal oscillation reaction is 35-40℃, and the reaction time is 10-14 h.

10. The method for preparing a posterior scleral reinforcement material according to claim 6, characterized in that, In step S4, the ultrasonic cleaning is performed by repeatedly cleaning with deionized water 3-5 times under the conditions of power 100-200W and frequency 40-60kHz, with each cleaning lasting 3-5 minutes. The crosslinking agent solution is a genipin solution with a concentration of 0.05%-0.2% (w / v), and the secondary crosslinking time is 3-5 hours. After the vacuum drying step, the obtained postscleral reinforcement material is subjected to an ethylene oxide sterilization step.

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