An injectable retinal sealant and method of preparation

Abstract

The present application belongs to the field of medical materials, and relates to an injectable retinal sealant and a preparation method, which comprises degradable adhesive powder and hydrophobic medium silicone oil, and the degradable adhesive powder and the hydrophobic medium are uniformly mixed in a certain proportion; the degradable adhesive powder is prepared into a gel by reacting modified hyaluronic acid with gelatin to form stable amide bonds, and then freeze-dried and ground into dry powder. In the treatment operation of a hole source retinal hole, the sealant is directly delivered to the retinal hole, and can be effectively adhered and simultaneously blocked by slight pressing, and the tissue sealant can be used underwater, so that the vitreous body does not need to be cut. The retinal sealant has low production cost, and has strong underwater tissue adhesion performance and excellent biocompatibility.

Description

Technical Field

[0001] This invention belongs to the field of medical materials and relates to an injectable retinal sealant and its preparation method, particularly an injectable sealant material that adheres and seals retinal tears in an intraocular liquid environment and its preparation method. Background Technology

[0002] Rhegmatogenous retinal detachment is a common blinding eye disease, primarily caused by retinal tears. Fluid from the vitreous cavity enters the subretinal space through these tears, leading to retinal detachment. Epidemiological surveys show that the annual prevalence of rhegmatogenous retinal detachment varies across regions, but the overall level is generally consistent with other countries worldwide. For example, in the Netherlands, a 2009 survey found an annual prevalence of 18.2 per 100,000; in Scotland, the annual prevalence was 12.05 per 100,000; and in Asian countries, South Korea's average annual prevalence from 2007 to 2011 was 10.39 per 100,000. While nationwide survey data is lacking in China, some regional surveys indicate a similar annual prevalence. Sealing the retinal tear is a crucial step in treating rhegmatogenous retinal detachment, and retinal tear sealants are an effective means of achieving this goal. Currently, the treatment of rhegmatogenous retinal detachment mainly relies on surgery. Although vitrectomy can effectively treat rhegmatogenous retinal detachment, the initial retinal reattachment rate is only 72% to 88%, and there is a risk of surgical complications such as proliferative vitreoretinopathy.

[0003] In rhegmatogenous retinal detachment surgery, the application of sealants significantly improves the success rate and patient prognosis. By using sealants, surgeons can more effectively close retinal tears, reducing surgical complications. Simultaneously, the use of sealants simplifies the surgical procedure and reduces surgical risks. Research on ointment-based sealants for rhegmatogenous retinal tears has been conducted against this backdrop. Ointment-based sealants prevent vitreous humor from entering between the retinal neuroepithelial layer and the pigment layer by covering the retinal tear, thereby preventing proliferative vitreoretinopathy and improving surgical success rates.

[0004] Early research focused primarily on various bioadhesives, such as cyanoacrylate adhesives and fibrin glue. Cyanoacrylate adhesives offer the advantage of rapid curing, typically requiring only minutes to hours to fully solidify, which helps shorten surgical time. However, while cyanoacrylate adhesives can quickly seal wounds, they exhibit significant toxicity, requiring strict dosage control. Furthermore, cyanoacrylate adhesives have relatively poor biocompatibility, potentially triggering tissue rejection or inflammatory reactions. Fibrin glue, prepared from human plasma, possesses excellent biocompatibility and is less likely to induce tissue rejection or inflammatory reactions. It can quickly and effectively adhere to retinal tissue, forming a fibrin curd that provides hemostasis and tissue adhesion. Although fibrin glue exhibits good biocompatibility and hemostatic properties, its relatively poor mechanical strength may prevent it from providing sufficient sealing, especially for larger retinal tears or areas requiring high tension.

[0005] This invention proposes a sealant based on a mixture of hyaluronic acid, gelatin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide ester (NHS), which is a dry powder mixed with silicone oil for sealing rhegmatogenous retinal tears. This sealant combines a hydrophobic matrix and adhesive microparticles, enabling rapid and strong adhesion under mild pressure. It allows for quick and stable sealing of the retinal tear by direct injection into the tear without vitreous body cutting, thus providing a new, simple, and convenient treatment method for rhegmatogenous retinal detachment. Summary of the Invention

[0006] To address the above problems, this invention proposes an injectable retinal sealant and its preparation method, providing a novel treatment for retinal tears. This involves removing only the vitreous above the retinal tear and then injecting a sealant into the tear. The sealant is composed of an adhesive dry powder and a hydrophobic matrix. The hydrophobic matrix removes the influence of the hydration layer on the retina on adhesion, while the powder provides rapid and strong adhesion, achieving rapid and stable sealing of the moist environment within the eye.

[0007] An injectable retinal sealant and its preparation method, characterized in that the preparation method includes the following steps: S1. Weigh out a certain amount of hyaluronic acid (HA) and dissolve it in deionized water. Stir thoroughly until it is completely dissolved. S2, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) is dissolved in deionized water to obtain an EDC solution, and N-hydroxysuccinimide ester (NHS) is dissolved in deionized water to obtain an NHS solution; S3: Place the completely dissolved hyaluronic acid solution from S1 into an ice bath and stir, while simultaneously adding EDC solution. Stir thoroughly for 10 minutes, then add NHS solution and stir for 30 minutes to obtain HA-NHS solution. S4, a certain amount of gelatin is dissolved in deionized water in a 60 ℃ oven to obtain a gelatin solution; S5, mix the gelatin solution prepared in step S4 and the HA-NHS solution prepared in step S3 in a certain proportion, stir at room temperature for 1 hour, and then dry and grind to obtain a biodegradable adhesive dry powder. S6, the adhesive dry powder obtained in step S5 is mixed with hydrophobic silicone oil to obtain an injectable retinal sealant.

[0008] In one embodiment, the hyaluronic acid has a molecular weight of 350-500 kDa.

[0009] In one embodiment, the concentration of the hyaluronic acid solution is 5 wt% to 10 wt%.

[0010] In one embodiment, the molar ratio of EDC solution to NHS solution is 2:1.

[0011] In one embodiment, the concentration of the gelatin solution is 5 wt% to 10 wt%.

[0012] In one embodiment, the complete drying method described in step S5 is to dry in a vacuum freeze dryer for 2 to 3 days.

[0013] In one embodiment, the grinding method in step S5 is grinding with a cryogenic grinder at 60 Hz for 10 min.

[0014] In one embodiment, the mass ratio of the adhesive dry powder to the hydrophobic silicone oil in step S6 is 1:1.

[0015] The adhesive dry powder in the sealant of this invention is a microparticle prepared by freeze-drying and grinding hyaluronic acid (HA) and gelatin after EDC / NHS activation and cross-linking reaction. When this dry powder is mixed with a hydrophobic matrix and injected into the retinal tear, the adhesive dry powder comes into direct contact with the retinal tissue after the silicone oil displaces the hydration layer. At this time, the carboxyl activated esters (from HA-NHS) in the dry powder rapidly react chemically with the amino groups in the tissue proteins to form strong amide bonds, achieving chemical adhesion. Simultaneously, the dry powder microparticles hydrate and swell rapidly upon contact with water. Due to physical entanglement and the interaction between residual functional groups, the gelatin and hyaluronic acid segments inside form a biocompatible hydrogel network, physically sealing the tear.

[0016] The sealant of this invention solves the problem of occlusion in the moist environment of the eye through the synergistic effect of the adhesive dry powder and the hydrophobic matrix. The hydrophobic matrix can displace the hydration layer of the pore surface and surrounding tissue, and the carboxyl-activated esters in the adhesive dry powder react chemically with the amino groups on the tissue. like Figure 4 This invention proposes an injectable, easy-to-use, immediate-sealing retinal tear sealant with good biocompatibility. Due to the sealant's hydrophobic matrix, it is unaffected by the hydration layer of the retina underwater, thus eliminating the need for complete vitreous removal. The sealant can be directly injected onto the retinal tear for successful adhesion and sealing. This sealant not only simplifies the procedure, achieving rapid and stable closure, but also preserves the patient's vitreous body, reducing postoperative relapse and avoiding complications. Attached Figure Description

[0017] The invention will now be described in more detail based on embodiments and with reference to the accompanying drawings, wherein: Figure 1 This demonstrates the effect of Embodiment 1 of the present invention on the sealing of pig small intestine; Figure 2 The adhesion strength test results of Examples 1-3 of the present invention with pigskin tissue are shown; Figure 3 The underwater adhesion effects of Embodiments 1 and 4 of the present invention are shown; Figure 4 A schematic diagram of the present invention for treating rhegmatogenous retinal detachment is shown. Detailed Implementation

[0018] The invention will be further described below with reference to the accompanying drawings. Example

[0019] like Figure 1 Hyaluronic acid (HA) at a concentration of 5 wt%, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) at 2 mmol, and N-hydroxysuccinimide ester (NHS) at 1 mmol were dissolved in deionized water and stirred evenly in an ice bath for later use. Gelatin at 5 wt% was dissolved in deionized water at 60 °C. First, the EDC solution was slowly added dropwise to the hyaluronic acid solution and stirred thoroughly for 10 min. Then, the NHS solution was added dropwise and stirred for another 30 min to obtain an HA-NHS solution. The HA-NHS solution and gelatin solution were mixed at a volume ratio of 1:1 and stirred at room temperature for 1 h to obtain a gel. The gel was freeze-dried under vacuum for 2-3 days and then ground at 60 Hz for 10 min using a cryo-mill to obtain an adhesive dry powder. Finally, it was mixed evenly with 10 cst silicone oil at a mass ratio of 1:1 to obtain a sealant. Example

[0020] 5 wt% hyaluronic acid (HA), 2 mmol 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and 1 mmol N-hydroxysuccinimide ester (NHS) were dissolved in deionized water and stirred evenly in an ice bath for later use. 10 wt% gelatin was dissolved in deionized water at 60 °C. First, the EDC solution was slowly added dropwise to the hyaluronic acid solution and stirred thoroughly for 10 min. Then, the NHS solution was added dropwise and stirred for another 30 min to obtain an HA-NHS solution. The HA-NHS solution and gelatin solution were mixed at a volume ratio of 1:1 and stirred at room temperature for 1 h to obtain a gel. The gel was freeze-dried under vacuum for 2-3 days and then ground at 60 Hz for 10 min using a cryo-mill to obtain an adhesive dry powder. Finally, it was mixed evenly with 10 cst silicone oil at a mass ratio of 1:1 to obtain a sealant. Example

[0021] 5 wt% hyaluronic acid (HA), 2 mmol 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and 1 mmol N-hydroxysuccinimide ester (NHS) were dissolved in deionized water and stirred evenly in an ice bath for later use. 2.5 wt% gelatin was dissolved in deionized water at 60 °C. First, the EDC solution was slowly added dropwise to the hyaluronic acid solution, and after stirring thoroughly for 10 min, the NHS solution was added dropwise, and stirring was continued for 30 min to obtain an HA-NHS solution. The HA-NHS solution and gelatin solution were mixed at a volume ratio of 1:1 and stirred at room temperature for 1 h to obtain a gel. The gel was freeze-dried under vacuum for 2-3 days, and then ground at 60 Hz for 10 min using a cryo-mill to obtain an adhesive dry powder. Finally, it was mixed evenly with 10 cst silicone oil at a mass ratio of 1:1 to obtain a sealant. Example

[0022] 5 wt% hyaluronic acid (HA), 2 mmol 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and 1 mmol N-hydroxysuccinimide ester (NHS) were dissolved in deionized water and stirred evenly in an ice bath for later use. 5 wt% gelatin was dissolved in deionized water at 60 °C. First, the EDC solution was slowly added dropwise to the hyaluronic acid solution, and after stirring thoroughly for 10 min, the NHS solution was added dropwise. Stirring was continued for 30 min to obtain an HA-NHS solution. The HA-NHS solution and gelatin solution were mixed at a volume ratio of 1:1 and stirred at room temperature for 1 h to obtain a gel. The gel was freeze-dried under vacuum for 2-3 days and then ground in a cryogenic mill at 60 Hz for 10 min to obtain an adhesive dry powder. Finally, it was mixed evenly with glycerin at a mass ratio of 1:1 to obtain a sealant.

[0023] Take the samples prepared in the above experimental example and perform the following experiments: Adhesion strength evaluation The retinal sealant samples prepared in Examples 1-3 above were used to conduct shear tensile strength tests on adhesion strength. Pigskin was cut into 5 cm * 3 cm rectangles, and the surface of the pigskin was cleaned with detergent. The prepared sealant was applied to the pigskin, and two pieces of pigskin were aligned and glued together in a straight line with a bonding area of ​​2 cm * 3 cm. After pressing with slight pressure for 15 seconds, the mixture was allowed to stand for 30 minutes. Finally, a shear test was conducted using a universal testing machine.

[0024] Figure 2 These are the adhesion strength test results for Examples 1-3. As can be seen from the figure, the adhesion strength is best when the ratio of gelatin to hyaluronic acid is 1:1. This is because when the ratio of hyaluronic acid to gelatin is 1:1, the molar ratio of carboxyl groups from hyaluronic acid to amino groups from gelatin is similar, resulting in the most complete cross-linking and the formation of a dense and uniform unit network structure, thereby achieving the strongest adhesion strength.

[0025] Sealing effect Take the retinal sealant prepared as described in Example 1 above, make a hole with a diameter of 2 mm in a pig small intestine filled with deionized water, apply the retinal sealant to the hole in the pig small intestine, press lightly for 15 seconds and then release. If no water flows out, the sealant is successful.

[0026] Figure 1 This is the small intestine sealing effect of Example 1. As can be seen from the figure, a clear column of water flows out of the rupture in the water-filled pig small intestine. When the sealant is applied to the rupture, no water can be observed flowing out, indicating successful sealing.

[0027] Underwater adhesion effect Take the retinal sealant prepared as described in Examples 1 and 4 above, and inject the samples of Examples 1 and 4 respectively into the surface of pigskin soaked in PBS buffer. After gelation, take it out and rinse the sealant under running water to observe whether it adheres firmly to the pigskin and is not washed off.

[0028] Figure 3 The figures show the underwater adhesion effects of Examples 1 and 4. As can be seen from the figures, the retinal sealant of Example 1, prepared with a hydrophobic matrix of silicone oil, still had a layer of sealant adhering to the tissue surface after rinsing with running water, while the retinal sealant of Example 4, prepared with a hydrophilic matrix of glycerol, completely fell off after rinsing with running water. This is because glycerol is soluble in water and excessively absorbs water and swells before the dry powder forms a gel, thus losing its adhesive effect.

Claims

1. An injectable retinal sealant, characterized in that, It includes biodegradable adhesive powder and hydrophobic silicone oil. The biodegradable adhesive powder and the hydrophobic medium are uniformly mixed in a certain proportion. The biodegradable adhesive powder is made by reacting modified hyaluronic acid with gelatin to form stable amide bonds to form a gel, which is then freeze-dried and ground to prepare a dry powder. The hydrophobic medium is low-viscosity silicone oil. The hydrophobic matrix can displace the hydration layer of the pore surface and surrounding tissue. The carboxyl activated ester in the adhesive dry powder reacts chemically with the amino groups on the tissue. Through the synergistic effect of the adhesive dry powder and the hydrophobic matrix, the adhesive powder comes into contact with the retina to form adhesion and achieve sealing.

2. A method for preparing an injectable retinal sealant, characterized in that, The preparation method Includes the following steps: S1, Weigh out a certain amount of hyaluronic acid HA and dissolve it in deionized water, stirring thoroughly until it is completely dissolved; S2, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC is dissolved in deionized water to obtain EDC solution, and N-hydroxysuccinimide ester NHS is dissolved in deionized water to obtain NHS solution; S3, place the completely dissolved hyaluronic acid solution from S1 into an ice bath and stir, while simultaneously adding EDC solution. After stirring thoroughly, add NHS solution and stir to obtain HA-NHS solution. S4, a certain amount of gelatin is dissolved in deionized water in an oven to obtain a gelatin solution; S5, mix the gelatin solution prepared in step S4 and the HA-NHS solution prepared in step S3 in a certain proportion, stir at room temperature, and then obtain the adhesive dry powder by complete drying and grinding. S6, the adhesive dry powder obtained in step S5 is mixed with hydrophobic silicone oil to obtain an injectable retinal sealant.

3. The method for preparing the injectable retinal sealant according to claim 2, wherein, The hyaluronic acid has a molecular weight of 350~500 kDa.

4. The method for preparing the injectable retinal sealant according to claim 2, wherein, The concentration of the hyaluronic acid solution is 5 wt% to 10 wt%.

5. The method for preparing the injectable retinal sealant according to claim 2, wherein, The molar ratio of the EDC solution to the NHS solution is 2:

1.

6. The method for preparing the injectable retinal sealant according to claim 2, wherein, The concentration of the gelatin solution is 5 wt% to 10 wt%.

7. The method for preparing the injectable retinal sealant according to claim 2, wherein, The complete drying method described in step S5 is to dry in a vacuum freeze dryer for 2-3 days.

8. The method for preparing the injectable retinal sealant according to claim 2, wherein, The grinding method described in step S5 is grinding with a cryogenic grinder at 60 Hz for 10 min.

9. The method for preparing the injectable retinal sealant according to claim 2, wherein, In step S6, the mass ratio of the adhesive dry powder to the hydrophobic silicone oil is 1:1.

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