Injectable double-layer drug sustained-release hydrogel as well as preparation method and application thereof

Abstract

According to the injectable double-layer drug sustained-release hydrogel and the preparation method and application thereof, hydrogel swelling and degradation curve and mechanical property detection shows that extrusion secondary injury to optic nerves can be avoided due to the swelling ratio ratio of 14% of inner-layer hydrogel to 10% of outer-layer hydrogel; the hydrogel precursor solution prepared by the preparation method disclosed by the invention has proper mechanical strength and adhesive force so as to cope with an in-vivo environment, has good injectability, can control the gelling time within 2 minutes, perfectly conforms to a short time window of optic nerve decompression surgery, and has extremely high clinical practical value. The problems that the serious operation risk of cerebrospinal fluid leakage during optic nerve local administration and a traditional local administration carrier lacks in-situ stability and is prone to displacement are solved, the damaged microenvironment can be cooperatively regulated and controlled, and long-acting slow release of nerve regeneration is promoted; multiple functions such as operation safety, medicine long-acting slow release, biocompatibility and operation convenience are successfully integrated, and an unprecedented effective strategy is provided for solving the clinical problem of optic nerve injury.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomedical materials and drug controlled release technology, and in particular to an injectable double-layer drug sustained-release hydrogel as well as a preparation method and application thereof. BACKGROUND

[0002] Optic nerve injury is a major blinding eye disease leading to irreversible vision loss, such as glaucoma, traumatic optic neuropathy, etc. The core pathological mechanism is the apoptosis of retinal ganglion cells and the degeneration of axons. At present, there is a lack of effective treatment to promote optic nerve repair and regeneration in clinic. The main challenge of drug treatment is that the optic nerve is part of the central nervous system, which is strictly regulated by the blood-retinal barrier and the blood-brain barrier, making it difficult for most drugs to effectively reach the lesion site when administered systemically (orally or intravenously), with very low bioavailability.

[0003] In order to overcome the above-mentioned barriers, previous studies have focused on local drug delivery strategies. The existing technology can be mainly divided into the following categories: Vitreous cavity injection Vitreous cavity injection is a common way of local drug delivery for posterior segment diseases. This method directly injects drugs into the vitreous cavity to act on the cell body of retinal ganglion cells. However, for the treatment of optic nerve injury, this method has inherent defects: drugs need to be transported in the reverse direction from the posterior segment of the eyeball through the axon to reach the optic nerve injury site. After injury, the axon transport function itself is severely damaged, making it difficult for drugs to reach the primary lesion site in a timely and sufficient manner for effective intervention, thus having little effect.

[0004] Optic nerve local drug delivery technology directly delivers drugs locally near the optic nerve to achieve precise treatment, which is a more promising direction. Previous studies have attempted to apply drugs or drug carriers directly to the surface of the optic nerve during optic nerve decompression surgery.

[0005] Although the above-mentioned optic nerve local drug delivery technology provides the possibility of drug release, there are the following serious defects and unsolved technical problems when it is directly applied to optic nerve local drug delivery: 1. Unable to effectively seal the dural incision, with the risk of cerebrospinal fluid leakage: The optic nerve is wrapped by the dura mater, and its lacuna is connected to the intracranial space and filled with cerebrospinal fluid. Any incision of the optic nerve sheath (dura mater) will cause cerebrospinal fluid leakage, leading to serious complications such as low intracranial pressure. The existing hydrogel technology mainly focuses on drug loading and release, and the material itself does not have sufficient biological adhesion or film-forming sealing properties, which cannot reliably seal the dural incision at the same time of drug delivery. This is a key obstacle to the conversion of laboratory concepts into clinically safe operations.

[0006] 2. Lack of in-situ stability, prone to displacement, leading to poor efficacy and potential risks: There is tissue pulsation and cerebrospinal fluid flow around the optic nerve. Ordinary hydrogel is only filled by simple injection, and has weak adhesion to nerve tissue, which is prone to displacement, shedding or being washed away, not only leading to the inability of the drug to act continuously at the lesion site, but also the risk of the shed material to the surrounding tissue.

[0007] 3. Single material is difficult to balance sealing, slow release and biocompatibility: High adhesion material may cause toxicity or compression injury to fragile nerve tissue; while biocompatible slow-release material often lacks immediate adhesion and sealing ability required for surgery. The prior art lacks a multifunctional integrated design that can simultaneously solve the problems of "instant sealing", "long-term slow release" and "nerve compatibility".

[0008] In summary, the prior art lacks a local drug delivery system that can be safely, effectively and conveniently used in optic nerve decompression surgery, which can not only achieve long-term drug slow release, but also reliably seal the dura mater and prevent cerebrospinal fluid leakage.

[0009] The technical problems to be solved include: 1. Solve the problem that systemic administration and intravitreal administration cannot effectively target the optic nerve injury lesion. Due to the existence of blood-eye / blood-brain barrier and axonal transport injury, the bioavailability of systemic administration is very low, and intravitreal administration has hysteresis, and the drug is difficult to effectively reach the primary injury site of the optic nerve.

[0010] 2. Solve the major surgical risk of cerebrospinal fluid leakage during local drug delivery of the optic nerve. After creating a dural window in the optic nerve canal decompression surgery, a barrier material is needed to instantly and reliably seal the incision to prevent cerebrospinal fluid leakage.

[0011] 3. Solve the problem of lack of in-situ stability and easy displacement of traditional local drug delivery carriers. The dynamic characteristics of the environment around the optic nerve require the drug delivery carrier to firmly adhere to the tissue surface and stay for a long time without being washed away by cerebrospinal fluid.

[0012] 4. Provide a long-acting slow-release platform that can synergistically regulate the injured microenvironment and promote nerve regeneration. A single drug is difficult to cope with the complex pathological process (such as inflammation, oxidative stress, and myelin disintegration) after optic nerve injury, and an intelligent carrier that can simultaneously carry multiple functional factors and control their release behavior is needed. SUMMARY

[0013] In order to solve the technical defects existing in the prior art, the present application provides an injectable double-layer drug slow-release hydrogel and a preparation method and application thereof.

[0014] The technical solution adopted by the present application is: an injectable double-layer drug sustained-release hydrogel, the hydrogel comprising an inner layer hydrogel and an outer layer hydrogel, the inner layer hydrogel being composed of methacrylated gelatin (GelMA) and 2-mercapto-1-methylimidazole by photo-crosslinking, and the inner layer hydrogel further loading drug-encapsulated nanoparticles, and the outer layer hydrogel being composed of methacrylated gelatin (GelMA) and oxidized dextran (ODex) by photo-crosslinking.

[0015] The concentrations of methacrylated gelatin (GelMA) and 2-mercapto-1-methylimidazole in the inner layer hydrogel are 20% w / v and 5% w / v, respectively.

[0016] The drug-encapsulated nanoparticles are mesoporous polydopamine nanoparticles MPDA@CLE encapsulating clemastine (CLE).

[0017] The concentrations of methacrylated gelatin (GelMA) and oxidized dextran (ODex) in the outer layer hydrogel are 20% w / v and 5% w / v, respectively.

[0018] The photo-crosslinking adopts LAP photo-initiator 405 nm wavelength blue-violet light irradiation for crosslinking.

[0019] A preparation method of the injectable double-layer drug sustained-release hydrogel, comprising the following steps: S1, synthesis of mesoporous polydopamine nanoparticles (MPDA): hydrochloric acid dopamine, triblock copolymer F127, anhydrous ethanol and deionized water are added and magnetically stirred at room temperature until the solid is completely dissolved, 1,3,5-trimethylbenzene (TMB) is added under continuous stirring, ultrasonic emulsification is carried out at 35°C constant temperature until the solution presents uniform milky white color, then it is moved to a 40°C constant temperature water bath, stirring is maintained, ammonia water is added dropwise, after the addition is completed, it is reacted in the dark until the reaction is completed, high-speed refrigerated centrifugation is carried out to discard the supernatant. The precipitate is washed with a mixed solution of anhydrous ethanol and deionized water, and then with a mixed solution of anhydrous ethanol and acetone, and centrifugation is carried out after each washing. The finally obtained precipitate is freeze-dried to obtain black MPDA powder; S2, preparation of MPDA loaded with clemastine (MPDA@CLE): the MPDA powder is dispersed in a clemastine phosphate buffer solution, and oscillation is carried out at room temperature in the dark; after the end, the precipitate is collected by centrifugation, the precipitate is gently washed with PBS, and freeze-drying is carried out to obtain MPDA@CLE powder; S3, preparation of the inner layer hydrogel solution: dissolve GelMA in PBS to prepare a solution with a concentration of 20%, add 2-mercapto-1-methylimidazole with a concentration of 5% and 0.25% of the photoinitiator LAP, stir uniformly and add MPDA@CLE nanoparticles loaded with clemastine, and photo-crosslinking to obtain the inner layer hydrogel solution loaded with MPDA@CLE nanoparticles; S4, preparation of the outer layer hydrogel solution: dissolve GelMA in PBS to prepare a solution with a concentration of 20%, add ODex with a concentration of 5% and 0.25% of the photoinitiator LAP, stir uniformly, and photo-crosslinking to obtain the outer layer hydrogel solution.

[0020] The volume ratio of anhydrous ethanol to deionized water and anhydrous ethanol to acetone in step S1 is 1:1 and 2:1, respectively.

[0021] The concentration of MPDA powder dispersed in clemastine phosphate buffer solution in step S2 is 1 mg / mL.

[0022] The application of the injectable double-layer drug sustained-release hydrogel in the preparation of a drug for local administration of optic nerve injury.

[0023] The drug for local administration of optic nerve injury is obtained by injecting the inner layer hydrogel solution in the injectable double-layer drug sustained-release hydrogel into the target site in the optic nerve sheath, irradiating with 405 nm blue-violet light, crosslinking and solidifying the inner layer hydrogel solution into non-adhesive GelMA-imid hydrogel, injecting and covering the outer layer hydrogel solution outside the solidified inner layer hydrogel, and irradiating again with 405 nm blue-violet light to crosslink and solidify the outer layer hydrogel solution into a double-network structure hydrogel with tissue adhesion.

[0024] The application provides an injectable double-layer drug sustained-release hydrogel, a preparation method and application thereof, and has the advantages that the swelling and degradation curves and mechanical property detection of the hydrogel show that the swelling rate ratio of the inner layer hydrogel 14% and the outer layer hydrogel 10% can avoid secondary damage to the optic nerve caused by extrusion, and the hydrogel precursor solution has good injectability, the gelation time can be controlled within 2 minutes, perfectly matches the short time window of the optic nerve decompression surgery, and has high clinical practical value. The application solves the major surgical risk of cerebrospinal fluid leakage during local administration of the optic nerve and the problems of lack of in-situ stability and easy displacement of the traditional local administration carrier, can synergistically regulate the injury microenvironment and promote long-acting sustained release of nerve regeneration, successfully integrates multiple functions such as surgical safety, long-acting sustained release of drugs, biocompatibility and operational convenience, and provides an unprecedented effective strategy for solving the clinical problem of optic nerve injury. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Transmission electron microscopy images of MPDA and MPDA-Cle.

[0026] Figure 2 Schematic diagram of crosslinking of the double-layer hydrogel system.

[0027] Figure 3 Injectability of the double-layer hydrogel system.

[0028] Figure 4 SEM micrographs of the double-layer hydrogel system.

[0029] Figure 5 Swelling and degradation curves of the double-layer hydrogel system.

[0030] Figure 6 In vitro drug release curves of the double-layer hydrogel system.

[0031] Figure 7 Tensile property test and burst pressure test of the double-layer hydrogel system.

[0032] Figure 8 Cell survival rate statistics and cell live / dead staining images.

[0033] Figure 9 Retinal OCT images.

[0034] Figure 10 Peripapillary tissue H&E staining sections. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0036] Example 1: Synthesis and characterization of mesoporous polydopamine nanoparticles (MPDA) Synthesis process: 0.5 g of dopamine hydrochloride and 0.5 g of triblock copolymer F127 (Pluronic® F-127) were weighed and placed in a 250 mL round-bottom flask.

[0037] 25 mL of anhydrous ethanol and 25 mL of deionized water were added, and the flask was placed on a magnetic stirrer and stirred at a speed of 500 rpm at room temperature for 30 minutes until the solid was completely dissolved.

[0038] Under continuous stirring, 0.8 mL of 1,3,5-trimethylbenzene (TMB) was slowly added using a pipette.

[0039] The flask was placed in an ultrasonic cleaner and sonicated at 35 °C for 30 min until the solution appeared milky white.

[0040] The flask was transferred to a 40 °C constant temperature water bath and maintained at 500 rpm stirring. 2 mL of ammonia solution (concentration: 25%) was slowly added dropwise at a rate of about 1 drop per second using a dropper.

[0041] After the dropwise addition was completed, the flask was wrapped with aluminum foil to avoid light and the reaction was continued at 40 °C and 500 rpm for 3 hours.

[0042] After the reaction was completed, the reaction solution was transferred to a 50 mL centrifuge tube and centrifuged at 4 °C and 11000 rpm for 30 min using a high-speed refrigerated centrifuge, and the supernatant was discarded.

[0043] The precipitate was washed 3 times with a mixture of anhydrous ethanol and deionized water (1:1, v / v) and 2 times with a mixture of anhydrous ethanol and acetone (2:1, v / v), and centrifuged at 11000 rpm for 10 min after each washing.

[0044] The final precipitate was placed in a freeze dryer and freeze-dried for 24 hours to obtain black MPDA powder, which was stored at 4 °C in the dark.

[0045] Characterization results: As shown in Figure 1 TEM (model: JEOL, Japan) observation showed that the synthesized MPDA nanoparticles were regular spherical and had obvious mesoporous structure.

[0046] Using a dynamic light scattering particle size analyzer (model: DLS, Malvern Instruments, UK), the hydrated particle size was determined to be 286.9 ± 10.5 nm and the Zeta potential was -39.1 ± 0.4 mV.

[0047] Example 2: Preparation of MPDA loaded clemastine (MPDA@CLE) and determination of drug loading rate Drug loading process: 10 mg of MPDA powder prepared in Example 1 was accurately weighed and dispersed in 10 mL of clemastine phosphate buffer solution (PBS, pH = 7.4) (initial concentration of clemastine: 1 mg / mL).

[0048] The mixture was placed in a shaker and shaken at 150 rpm for 24 hours at room temperature in the dark.

[0049] After loading, the dispersion was transferred to a centrifuge tube and centrifuged at 4°C, 12000 rpm for 20 minutes, and the precipitate was collected.

[0050] After washing the precipitate with PBS twice, it was freeze-dried to obtain MPDA@CLE powder.

[0051] Drug loading rate determination: The concentration of clemastine in the supernatant before and after loading was determined by UV-Vis spectrophotometry (UV-Vis, model: UV-1780, Shimadzu, Japan), and the drug loading amount was calculated by the standard curve.

[0052] The drug loading rate of MPDA@CLE was calculated to be 15.28% ± 0.13%.

[0053] Example 3: Preparation and physicochemical property characterization of double-layer hydrogel Preparation of hydrogel precursor solution: Outer hydrogel solution (G20OD5): 200 mg of GelMA powder (degree of substitution DS = 30) was weighed and dissolved in 1 mL of PBS (pH = 7.4) in a 37°C water bath to completely dissolve, obtaining a 20% (w / v) GelMA solution. Then 50 mg of ODex (oxidation degree: 105.89 ± 15.88%) and 2.5 mg of LAP photoinitiator were added and vortexed to mix evenly, with a final concentration of GelMA 20%, ODex 5%, and LAP 0.25%.

[0054] Inner hydrogel solution (G20imid5): 200 mg of GelMA powder was weighed and dissolved in 1 mL of PBS, and the operation was the same as above to prepare a 20% solution. 50 mg of 2-mercapto-1-methylimidazole and 2.5 mg of LAP were added and vortexed to mix evenly, with a final concentration of GelMA 20%, 2-mercapto-1-methylimidazole 5%, and LAP 0.25%. As needed, an appropriate amount of MPDA@CLE was added to this solution.

[0055] Gelation performance test: 100 μL of the above solution was taken on a glass slide and irradiated with a 405 nm wavelength ultraviolet light crosslinking box (light intensity: 30 mW / cm 2 ) for 2 minutes. Observation by the inverted method showed that both formulations formed stable hydrogels within 2 minutes.

[0056] Injectability and light curing performance: Both hydrogel precursor solutions could be easily injected using a 22G syringe, and the injection process was smooth without blockage. For example,Figure 3 As shown, under irradiation with 405 nm blue-violet light (light intensity: 10 mW / cm²), both solutions completed cross-linking within 90 seconds, forming a structurally stable hydrogel that met the time requirements for surgical procedures.

[0057] Morphological observation: like Figure 4 As shown, the gelled hydrogel was freeze-dried, sputter-coated with gold, and observed using a scanning electron microscope (SEM, Thermo Fisher Scientific, USA). Both the inner and outer hydrogel layers exhibit a porous three-dimensional network structure.

[0058] Swelling and degradation behavior: like Figure 5 As shown, the swelling curve was obtained by immersing the weighed dry gel (W0) in PBS and allowing it to swell to equilibrium at 37°C before weighing (W1). The swelling ratio (SR) was calculated as (W1 - W0) / W0 × 100%. The swelling ratio of the inner hydrogel was approximately 14%, and that of the outer layer was approximately 10%. This indicates that the gel is dimensionally stable in a hydrated environment and is unlikely to cause compression damage to the optic nerve tissue due to excessive swelling.

[0059] Degradation curve: In PBS containing collagenase (1 U / mL) at 37°C, a known weight of hydrogel (W) was added. i Immerse the sample in PBS containing 1 U / mL collagenase and shake at 37°C. Periodically remove the sample, blot dry, and weigh (W1). Calculate the remaining mass percentage = (W1 / W) i () × 100%. The hydrogel exhibits a slow degradation trend. The inner layer of the hydrogel completely degrades in about 300 hours, and the outer layer in about 324 hours, indicating that it can provide sustained drug release support and physical barrier function for up to several weeks in vivo.

[0060] In vitro drug release curve The in vitro release of chlormastine was studied in PBS (pH=7.4, 37°C) using the dialysis bag method. The cumulative release rates of free chlormastine, chlormastine loaded in a monolayer hydrogel (Gel / CLE), and MPDA@CLE loaded in the bilayer hydrogel of this invention (Gel / MPDA@CLE) were compared.

[0061] like Figure 6 As shown, the bilayer hydrogel system (Gel / MPDA@CLE) of this invention exhibits a significant sustained-release effect, with the drug being released continuously for more than 168 hours (1 week) without any obvious burst release phenomenon, which meets the needs of long-acting treatment.

[0062] Biocompatibility evaluation of bilayer hydrogels Mechanical property testing: As shown in Figure 7 , tensile and adhesion test: the test was performed using a texture analyzer (model: CTX, Brookfield Ametek, USA). The outer hydrogel G20OD5 showed good tensile properties and wet tissue adhesion strength. The burst pressure test showed that it could withstand a pressure higher than 11.3 mmHg.

[0063] In vitro cytotoxicity experiment (CCK-8 method): The rat retinal ganglion cell line (R28) was used for testing. The cells were co-cultured with the conventional culture medium (Control), the outer hydrogel extract (GM-Odex), the inner hydrogel extract (GM-imid), and the inner and outer hydrogel drug-loaded complex (GO / GI@MPDA-Cle) for 24h, 48h and 72h, respectively.

[0064] As shown in Figure 8 , the results showed that there was no significant difference in cell survival rate between the inner and outer hydrogel extract groups and the Control group (p>0.05), and no obvious dead cells were observed after co-culture in the inner and outer hydrogel extract groups. It showed that the material extract had no obvious cytotoxicity.

[0065] In vivo tissue compatibility observation: After applying the double-layer hydrogel of the application to the rat optic nerve, the retinal structure was observed by optical coherence tomography (OCT) at different time points, and the periocular tissue was taken for histological section (H&E staining).

[0066] As shown in Figure 9 , the application of hydrogel showed that the structure of each layer of the retina was clear, and there was no obvious edema or detachment.

[0067] As shown in Figure 10 , the results showed that compared with the sham operation group (Sham), only mild inflammatory cell infiltration was observed in the hydrogel application site (Gel), and no necrosis or other organic damage was observed, indicating that it had good in vivo tissue compatibility.

[0068] Notes for all technicians: although the application has been described according to the above specific embodiments, the inventive idea of the application is not limited to this application, and any modification using the inventive idea will be included in the patent protection scope of this patent.

[0069] The above merely describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. An injectable bi-layer drug-releasing hydrogel, characterized in that, The hydrogel comprises an inner layer hydrogel and an outer layer hydrogel, the inner layer hydrogel is composed of methacrylated gelatin GelMA and 2-mercapto-1-methyl imidazole by photo-crosslinking, and the inner layer hydrogel further loads drug-loaded nanoparticles, and the outer layer hydrogel is composed of methacrylated gelatin GelMA and oxidized dextran ODex by photo-crosslinking.

2. The injectable bi-layer drug release hydrogel according to claim 1, wherein, The concentration of methacrylated gelatin GelMA and 2-mercapto-1-methyl imidazole in the inner layer hydrogel is 20% w / v and 5% w / v respectively.

3. The injectable bi-layer drug release hydrogel according to claim 1, wherein, The drug-loaded nanoparticles are mesoporous polydopamine nanoparticles MPDA@CLE loaded with clemastine CLE.

4. The injectable bi-layer drug release hydrogel according to claim 1, wherein, The concentration of methacrylated gelatin GelMA and oxidized dextran ODex in the outer layer hydrogel is 20% w / v and 5% w / v respectively.

5. The injectable bi-layer drug release hydrogel according to claim 1, wherein the bi-layer drug release hydrogel is characterized by, The photo-crosslinking adopts blue-violet light irradiation of LAP photo-initiator 405 nm wavelength for crosslinking.

6. A process for the preparation of the injectable bi-layered drug releasing hydrogel as claimed in claim 1, wherein the process comprises of the steps of: Comprise the following steps: S1, synthesis of mesoporous polydopamine nanoparticles MPDA: hydrochloric acid dopamine and triblock copolymer F127, add anhydrous ethanol and deionized water, magnetic stirring at room temperature, until the solid is completely dissolved, under the condition of continuous stirring, after adding 1,3,5-trimethylbenzene TMB, ultrasonic emulsification at 35 DEG C constant temperature, until the solution presents uniform milky white, then move to 40 DEG C constant temperature water bath, maintain stirring, dropwise add ammonia water, after dropwise addition is completed, avoid light, continue to react until the reaction is completed, high-speed refrigerated centrifugation is discarded, the precipitate is washed with a mixed solution of anhydrous ethanol and deionized water, and then washed with a mixed solution of anhydrous ethanol and acetone, centrifugation is carried out after each washing, and the finally obtained precipitate is freeze-dried to obtain black MPDA powder; S2, preparation of MPDA loaded with clemastine MPDA@CLE: disperse MPDA powder in clemastine phosphate buffer solution, oscillate at room temperature and in the dark; after completion, collect the precipitate by centrifugation, wash the precipitate with PBS, and freeze-dry to obtain MPDA@CLE powder; S3, preparation of inner layer hydrogel solution: dissolve GelMA in PBS to prepare a solution with a concentration of 20%, add 2-mercapto-1-methyl imidazole with a concentration of 5% and 0.25% photo-initiator LAP, stir uniformly and add MPDA@CLE nanoparticles loaded with clemastine, and photo-crosslinking to obtain inner layer hydrogel solution loaded with MPDA@CLE nanoparticles; S4, preparation of outer layer hydrogel solution: dissolve GelMA in PBS to prepare a solution with a concentration of 20%, add ODex with a concentration of 5% and 0.25% photo-initiator LAP, stir uniformly, and photo-crosslinking to obtain outer layer hydrogel solution.

7. The production method according to claim 6, wherein The volume ratio of anhydrous ethanol to deionized water and anhydrous ethanol to acetone in step S1 is 1:1 and 2:1 respectively.

8. The preparation method according to claim 6, characterized in that, The concentration of MPDA powder dispersed in clemastine phosphate buffer solution in step S2 is 1 mg / mL.

9. Use of the injectable double-layer drug release hydrogel according to claim 1 in the preparation of a medicament for local administration of optic nerve injury.

10. Use according to claim 9, characterized in that, The medicament for local administration of optic nerve injury is prepared by injecting the inner hydrogel solution of the injectable double-layer drug release hydrogel to the target site in the optic nerve sheath, irradiating with 405 nm blue-violet light, crosslinking and solidifying the inner hydrogel solution into the non-adhesive GelMA-imid hydrogel, injecting and covering the outer hydrogel solution outside the solidified inner hydrogel, and irradiating again with 405 nm blue-violet light to crosslink and solidify the outer hydrogel solution into the double-network structure hydrogel with tissue adhesion.

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