Photodegradable hydrogel as well as preparation method and application thereof

Abstract

The invention discloses photodegradable hydrogel as well as a preparation method and application thereof, and belongs to the technical field of intelligent high polymer materials. The photodegradable hydrogel is formed by polymerizing a macromonomer containing a light-controlled bond breaking unit; wherein the macromonomer containing the light-controlled broken bond unit is formed by covalently connecting a macromolecular chain, a light response breaking functional group and a molecular fragment containing a catechol structure through a chemical bond. The preparation method specifically comprises the following steps: (1) synthesizing an intermediate A containing a photoresponse fracture functional group; (2) carrying out a coupling reaction with a molecular fragment containing a catechol structure; (3) carrying out a coupling reaction with a polymer chain containing an active functional group in a solvent under the catalytic action of a condensing agent; (4) dissolving in a dispersion medium; (5) dissolving an oxidizing agent in water; and (6) uniformly mixing, and standing to obtain the product. The photodegradable hydrogel disclosed by the invention is suitable for various scenes such as biological tissue adhesion, flexible electronic packaging, drug controlled release and implantable medical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent polymer materials, and more particularly to a photodegradable hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogels are widely used in many fields due to their excellent biocompatibility and similarity to human soft tissue. They are an important class of biomedical materials and have been widely used in drug carriers, cell carriers, tissue repair, biosensors, and other fields. In recent years, bioadhesive hydrogels, with their superior wet adhesion and mechanical properties that match those of biological soft tissue, can conform well to uneven biological tissue surfaces in dynamic environments. As a result, they have found widespread application in wound hemostasis, wound repair, tissue adhesion, and the bonding of flexible electronic devices.

[0003] To impart excellent adhesion properties to hydrogels, researchers have widely used covalent or non-covalent modification methods with succinimide-activated esters (NHS) and dopamine / catechol structural units. NHS esters can undergo amidation reactions with amino groups on the tissue surface, forming stable covalent bonds and enhancing adhesion strength to soft tissues. Catechol structures (such as dopamine and 3,4-dihydroxyphenylethylamine) can establish strong adhesion interfaces with a variety of substrates, including metals, polymers, and biological tissues, through hydrogen bonding, metal coordination, π-π stacking, and oxidative covalent coupling.

[0004] For example, patent CN 118829398 A discloses a system and method for configuring personal wearable electronic devices for extended wear. The system provides a coupling agent made from a hydrogel-elastomer mixture modified with N-hydroxysuccinimide. This bioadhesive hydrogel can connect the coupling agent, the electronic device, and human skin, while the coupling agent component can be used to couple and transmit information to and from the electronic device.

[0005] Patent CN 113057637 A discloses a flexible bioelectrode array based on dopamine hydrogel and its manufacturing method. The bioelectrode array of this invention selects a stretchable flexible substrate, utilizes the bioadhesive properties of dopamine hydrogel, and combines it with a serpentine line structure design. This makes this flexible bioelectrode array more compatible with the mechanical properties of brain tissue, has a larger effective contact area with brain tissue, can collect higher-quality signals, and improves the safety of the electrode array in application.

[0006] However, while these strategies have significantly enhanced the bioadhesive properties of hydrogels, "controlled debonding" remains a core challenge for these materials. During the replacement of wound dressings, removal of tissue sealants, or recycling of flexible electronic devices, conventional strongly adhesive hydrogels often struggle to achieve interfacial detachment, easily causing tissue tearing, increased inflammatory responses, and even secondary tissue trauma. Furthermore, once the material loses its integrity, it is difficult to reuse or quickly integrate it into new devices, hindering the sustainable design of flexible devices. To address this issue, some studies have attempted to introduce photoresponsive degradation structures into hydrogel systems. For example, patents CN 114262408 A and CN 108794737 A utilize nitrophenylethyl ester photolytic units to achieve controlled network structure fracture or gel-sol transition. However, these photoresponsive systems are mostly based on a single structural degradation mechanism, lack broad-spectrum adhesion in molecular design, and struggle to work synergistically with different substrate surfaces.

[0007] Therefore, how to develop a photoresponsive adhesive hydrogel with excellent performance is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a photodegradable hydrogel and its preparation method and application, so as to solve the problems of uncontrollable adhesion performance, single degradation mode, and structural and functional separation of hydrogel materials in the prior art.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A photodegradable hydrogel, which is polymerized from macromonomers containing photo-controlled bond-breaking units;

[0011] Among them, the macromonomer containing the photo-controlled cleavage bond unit is composed of a polymer chain, a photoresponsive cleavage functional group and a molecular fragment containing a catechol structure covalently connected by chemical bonds.

[0012] The novelty and applicability of the photodegradable hydrogel of the present invention are as follows:

[0013] 1. The present invention constructs a hydrogel material with photoresponsive degradation characteristics and bioadhesion properties by combining photoresponsive cleavage units with adhesion groups containing catechol structures. The hydrogel material is suitable for various scenarios such as biological tissue adhesion, flexible electronic packaging, drug controlled release, and implantable medical devices.

[0014] 2. The present invention provides a photoresponsive adhesive hydrogel, a photoresponsive macromolecular monomer constructed by a photoresponsive cleavage unit and an adhesive group containing a catechol structure, combined with the oxidative cross-linking reaction of the catechol structure, to construct a controllable debonding hydrogel network with high adhesion and photoresponsiveness.

[0015] 3. The present invention realizes the integration of intelligent responsiveness, controllable degradation and bioadhesion function of hydrogel materials through the coordinated construction of polymer main chain, photoresponsive cleavage structure and catechol adhesion group.

[0016] 4. The photodegradable hydrogel of the present invention can realize gel-sol transformation or degradation under ultraviolet light (300-405nm), has excellent light response performance and tissue adhesion ability, and can be treated with sodium periodate, Fe 3+ Or H2O2 / HRP system to achieve rapid cross-linking, suitable for controlled debonding, hydrogel encapsulation, biological tissue adhesion, flexible electronic device connection, light-controlled drug release and other fields, with good biocompatibility and application prospects.

[0017] 5. The photodegradable hydrogel of the present invention has good responsiveness to ultraviolet light in the wavelength range of 300-405 nm, and can achieve gel-sol transition or significantly reduce its adhesion strength after irradiation.

[0018] 6. The cross-linking points of the photodegradable hydrogel of the present invention are composed of phenolquinone-phenolquinone coupling structures formed by oxidation of catechol groups. The degree of cross-linking is regulated by the modification rate of the main chain ends, ranging from 20% to 100%, preferably above 90%.

[0019] 7. The gel cross-linking network of the photodegradable hydrogel of the present invention is formed by mutual oxidation cross-linking of catechol and is covalently connected to the photosensitive structure. It has good flexibility, adhesion and controllable degradation properties under light.

[0020] 8. The photodegradable hydrogel of the present invention combines rationality in structural design with high integration of application functions. It has good biocompatibility in the in vivo environment and exhibits a certain free radical scavenging ability, which helps to inhibit tissue fibrosis reactions. It can be applied to various surfaces such as wood, metal, rubber, plastic, and skin tissue to achieve broad-spectrum adhesion.

[0021] Furthermore, the above-mentioned polymer chain is a hydrophilic polymer main chain or an amphiphilic polymer main chain containing a flexible segment, preferably at least one of polyethylene glycol (PEG), polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) block copolymer (Pluronic), poly(polyethylene glycol methacrylate) (POEGMA), polycaprolactone-polyethylene glycol (PCL-PEG) block copolymer, poly(lactic acid-glycolic acid)-polyethylene glycol (PLGA-PEG) block copolymer and poly(lactic acid-glycolic acid)-polyethylene glycol-poly(lactic acid-glycolic acid) (PLGA-PEG-PLGA) triblock copolymer.

[0022] Furthermore, the polymer chain is at least one of linear polyethylene glycol, three-arm polyethylene glycol, four-arm polyethylene glycol and eight-arm polyethylene glycol, and has a number average molecular weight of 1000-50000 Daltons.

[0023] A further beneficial effect of the above is that the polymer chains selected in the present invention are used to provide controllable mechanical properties and network flexibility.

[0024] Furthermore, the photoresponsive cleavage functional group is connected to the end or side group of the polymer chain and is at least one of o-nitrobenzyl ester, coumarin, anthracene, thymine and O-acyl oxime.

[0025] A further beneficial effect of the above is that the photoresponsive cleavage functional group selected in the present invention can undergo a cleavage reaction under irradiation with ultraviolet light of a specific wavelength (300-405 nm), thereby achieving structural disintegration or degradation of the hydrogel.

[0026] Furthermore, the molecular fragment containing catechol structure is at least one of dopamine, catechin, epicatechin, protocatechuic acid, catecholamine and tannic acid.

[0027] A further beneficial effect of the above method is that the molecular fragments containing catechol structures selected by the present invention can form strong adhesion to the surfaces of various materials and have antioxidant and tissue-friendly properties.

[0028] A method for preparing the above-mentioned photodegradable hydrogel specifically comprises the following steps:

[0029] (1) synthesizing an intermediate A containing a photoresponsive cleavage functional group;

[0030] (2) coupling the intermediate A with a molecular fragment containing a catechol structure to obtain a photosensitive adhesion small molecule structural unit B;

[0031] (3) coupling the photosensitive adhesive small molecule structural unit B with the polymer chain containing active functional groups in a solvent under the catalytic action of a condensation agent to obtain a macromolecular monomer containing a photo-controlled bond-breaking unit;

[0032] (4) dissolving the macromonomer containing the photo-cleavable bond in a dispersion medium to obtain a macromonomer solution for later use;

[0033] (5) dissolving the oxidant in water to obtain an oxidant aqueous solution;

[0034] (6) Adding the oxidant aqueous solution to the macromonomer solution, mixing them evenly, and allowing them to stand, thereby obtaining the photodegradable hydrogel.

[0035] Furthermore, in the above step (3), the condensing agent is at least one of 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate / N,N-diisopropylethylamine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide, N,N'-dicyclohexylcarbodiimide / 1-hydroxybenzotriazole, 1,1'-carbonyldiimidazole and triphosgene.

[0036] Furthermore, in the above step (3), the solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

[0037] Furthermore, in the above step (4), the dispersion medium is 10 mM PBS buffer solution containing 0.15 M NaCl and pH 7.4, physiological saline or deionized water; the mass concentration of the macromolecular monomer solution is 10%-60%, preferably 10%, 12%, 15%, 20%, 25% or 50%.

[0038] Furthermore, in the above step (5), the oxidant is sodium periodate, ferric chloride or H2O2 / HRP; the mass concentration of the oxidant aqueous solution is 0.5%-10%, preferably 0.5%, 1.0%, 2.5%, 5% or 10%.

[0039] Furthermore, in the above step (6), the volume ratio of the macromonomer solution to the oxidant aqueous solution is 1:(1-9), preferably 1:1, 1:2, 1:5, 1:8 or 1:9; the mixing is carried out by vortex oscillation or gentle stirring.

[0040] The present invention also seeks to protect the use of the above-mentioned photodegradable hydrogel or the photodegradable hydrogel prepared by the above-mentioned preparation method in the preparation of drug carriers, cell carriers, biological tissue sealants, brain-computer interfaces and flexible electronic device adhesives.

[0041] The ultraviolet light response characteristic of the photodegradable hydrogel of the present invention is that after irradiation with ultraviolet light in the 365-405 nm band for 1-5 minutes, the o-nitrobenzyl ester structure rapidly undergoes a CO bond cleavage reaction, resulting in degradation of the network structure, conversion of the gel into a sol, and rapid debonding.

[0042] The on-demand debonding mechanism of the photodegradable hydrogel of the present invention is: light irradiation→fracture of o-nitrobenzyl ester→gel disintegration→interfacial release.

[0043] This response process is fast and controllable, and can avoid secondary damage to the tissue caused by the tearing process of traditional high-adhesion hydrogels.

[0044] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] 1. Modular structure and highly integrated functions

[0046] By synergistically integrating the ternary structure of a hydrophilic or amphiphilic polymer main chain, a photoresponsive cleavage unit, and a catechol adhesion group, the synergistic optimization of three key properties, namely, flexible mechanical properties, phototriggered degradation, and bioadhesion, is achieved, with a clear structural design and unified functions.

[0047] 2. Controllable photoresponse performance

[0048] By introducing photosensitive functional groups such as o-nitrobenzyl ester and coumarin, the hydrogel material is endowed with the ability to reversibly or irreversibly degrade under 300-405nm ultraviolet light, achieving non-contact and non-invasive structural response, and meeting the development needs of smart medical materials.

[0049] 3. Excellent bioadhesion ability

[0050] The catechol structure can form a strong adhesion interface with a variety of substrates (such as biological tissues, metals, plastics, and rubbers), is particularly suitable for long-term adhesion in humid environments, and has good biocompatibility.

[0051] 4. Combination of responsive debonding and degradable properties

[0052] Hydrogel materials can achieve rapid debonding or gel-sol transition after light exposure, and are suitable for constructing on-demand peelable tissue adhesives, temporary packaging materials, and interface protection layers for flexible devices, avoiding secondary surgical intervention and reducing tissue damage.

[0053] 5. Adjustable cross-linking density and mechanical properties

[0054] By controlling the modification rate of the main chain end groups and the density of catechol groups, the cross-linking degree, adhesion strength and elastic modulus of the hydrogel can be flexibly adjusted to adapt to the surface characteristics of different tissues or devices.

[0055] 6. Strong biological function scalability

[0056] The catechol structure itself has certain antioxidant activity and can scavenge free radicals. It is expected to be used in functional medical scenarios such as alleviating post-implantation inflammatory reactions and delaying tissue fibrosis.

[0057] 7. The synthesis process is simple and suitable for large-scale preparation

[0058] The synthesis process of hydrogel materials is based on mature condensation reactions and oxidative cross-linking strategies. The raw materials are widely available and the reaction conditions are mild, providing a good foundation for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a schematic diagram of the network construction of the hydrogel in Example 1;

[0060] Figure 2 This is a photo of the gel-sol transition produced by illumination of the hydrogel in Example 1;

[0061] Figure 3 The results of the light rheological test of the hydrogel in Example 1 are as follows;

[0062] Figure 4 These are the lap-shear adhesion test results of the hydrogel in Example 1 on different substrates before and after irradiation. DETAILED DESCRIPTION

[0063] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0064] Example 1

[0065] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0066] (1) Vanillyl acetone (30 g, 180.5 mmol) was dissolved in 150 mL of anhydrous DMF, and ethyl 4-bromobutyrate (31 mL, 217 mmol) and potassium carbonate (37.4 g, 271 mmol) were added in sequence. The mixture was stirred overnight under a nitrogen atmosphere. After the reaction was completed, the reaction solution was poured into 2 L of ice water for sedimentation, stirred at room temperature for 2 h, and allowed to stand at 4 °C overnight. The precipitate was filtered and vacuum dried to obtain intermediate 1 (ethyl 4-(4-acetyl-2-methoxyphenoxy)butyrate) with a yield of 95%.

[0067] (2) Intermediate 1 (25 g, 89 mmol) was added in batches to 70 mL of 70% concentrated nitric acid pre-cooled in an ice bath, with the temperature controlled not to exceed 35°C. After reacting at 32°C for 1 h, the mixture was added dropwise to 4°C deionized water for precipitation. The mixture was stirred, allowed to stand, and filtered to obtain intermediate 2 (nitration product). The mixture was recrystallized from ethanol to obtain a light yellow solid with a yield of 60%.

[0068] (3) Intermediate 2 (6.36 g, 19.5 mmol) was dissolved in ethanol (100 mL). After bubbling nitrogen at 38°C, sodium borohydride (0.459 g, 12.1 mmol) was slowly added and stirred overnight to obtain a red solution. After sedimentation and filtration, yellow powder intermediate 3 (reduction product) was obtained with a yield of 62%.

[0069] (4) Intermediate 3 (3.58 g, 10.9 mmol) was dissolved in 15 mL of anhydrous pyridine and azeotropically dehydrated. The mixture was then dissolved in 30 mL of anhydrous DCM (dichloromethane), and CDI (2.66 g, 16.4 mmol) was added. The mixture was stirred at room temperature in the dark for 2.5 h, and then dopamine hydrochloride (6.22 g, 32.8 mmol) and triethylamine (5.32 mL, 38.3 mmol) were added. The mixture was reacted in 20 mL of anhydrous DMF for 24 h. The solvent was removed by rotary evaporation, and the mixture was purified by silica gel column chromatography (methanol / DCM = 1:4) to obtain an orange solid intermediate 4 (amide coupling product) with a yield of 66%.

[0070] (5) Intermediate 4 (4.89 g, 9.7 mmol) and sodium hydroxide (0.57 g, 14.5 mmol) were dissolved in EtOH / H2O (3:1, 50 mL), stirred at room temperature overnight, and the solvent was removed by rotary evaporation. The mixture was redissolved in water and the pH was adjusted to ~4. The mixture was centrifuged and washed to obtain brown solid intermediate 5 (o-nitrobenzyl dopamine photosensitive small molecule o-NB-DA) with a yield of 60%.

[0071] (6) PEG (Mn = 6000, 10 g, 1.66 mmol) and triethylamine (5.54 mL, 40 mmol) were dissolved in 120 mL of anhydrous DCM and stirred in an ice bath. Methanesulfonyl chloride (3.6 mL, 46.5 mmol) was dissolved in 40 mL of anhydrous DCM and slowly added at a rate of 2 h. The reaction was continued in an ice bath for 48 h. After the reaction, deionized water and DCM (100 mL:40 mL) were added. The phases were separated using a separatory funnel. The organic phase was washed with 1N HCl and saturated NaCl in sequence. After drying and settling, PEG-SO2CH3 (9.7 g) was obtained with a yield of 97%.

[0072] (7) PEG-SO2CH3 was dissolved in 300 mL of concentrated ammonia water, and ammonium chloride (35.5 g, 663.8 mmol) was added. The mixture was reacted at room temperature for 48 h. NaCl (36 g) was added and the mixture was extracted with DCM. The organic phase was dried and precipitated to obtain PEG-NH2 (9.5 g) with a yield of 95%.

[0073] (8) Intermediate 5 (2.65 g, 5.54 mmol) was dissolved in 20 mL of anhydrous DMF, and HBTU (2.1 g, 5.54 mmol) and DIPEA (0.96 mL, 5.54 mmol) were added. PEG-NH2 (10.13 g, 1.68 mmol) was dissolved in 10 mL of DMF and slowly added to the reaction solution. The reaction was allowed to react at room temperature for 48 h. The reaction solution was diluted with DCM and washed with saturated NaHCO3, 1N HCl, and saturated NaCl solutions in sequence. After drying and concentration, a yellow solid was precipitated. The solid was dissolved in deionized water and dialyzed for 3 days (MWCO = 3500). Finally, it was freeze-dried to obtain PEG-o-NB-DA (9.5 g, Mw = 6000) with a yield of 95%.

[0074] (9) Weigh 200 mg of PEG-o-NB-DA and add it to 0.9 mL of PBS buffer. Vortex and mix thoroughly to dissolve it completely, forming a viscous, transparent macromer solution.

[0075] (10) Add 0.1 mL of 5.4 wt% sodium periodate aqueous solution and mix thoroughly immediately. Let the mixture stand at room temperature for 15 s.

[0076] (11) The gelation process was completed within 2 min to form a stable, light brown, transparent photodegradable hydrogel (e.g. Figure 1 It has good self-supporting performance.

[0077] Example 2

[0078] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0079] (1) 4-Hydroxycoumarin (6.0 g, 33.3 mmol) was weighed and dissolved in 100 mL of anhydrous DMF. 4-Bromobutyric acid (4.5 mL, 39.6 mmol) and potassium carbonate (6.0 g, 43.5 mmol) were added and stirred at room temperature under nitrogen atmosphere for 24 h. The reaction solution was poured into 300 mL of ice water for precipitation, filtered, and dried to obtain a light yellow solid 4-hydroxycoumarin butyrate with a yield of 88%.

[0080] (2) The above-mentioned coumarin butyrate (3.0 g, 11 mmol) and epicatechin (5.2 g, 18.4 mmol) were dissolved in 50 mL of anhydrous DMF, and EDC·HCl (3.8 g, 19.8 mmol), NHS (2.3 g, 19.8 mmol) and triethylamine (3.0 mL, 21.5 mmol) were added. The mixture was reacted at room temperature in the dark for 24 h. After the reaction, the solvent was evaporated to obtain a viscous orange intermediate, which was purified by silica gel column to obtain a solid product.

[0081] (3) Dissolve four-arm PEG-NH2 (Mn≈10,000 Da, 10 g, 1.0 mmol) in 100 mL of anhydrous DMSO;

[0082] (4) The solid product (1.5 g) from step (2) was dissolved in 20 mL of DMF, and HBTU (1.1 g, 2.9 mmol) and DIPEA (0.5 mL, 2.9 mmol) were added and mixed for activation for 10 min. The mixture was then slowly added dropwise to the PEG-NH2 solution and reacted at room temperature for 48 h.

[0083] (5) The reaction solution was diluted with DCM, washed with 1N HCl, saturated NaHCO3 and saturated NaCl solution, dried, and concentrated by rotary evaporation to obtain a yellow solid.

[0084] (6) The yellow solid was dissolved in deionized water and dialyzed using a dialysis bag with a MWCO of 3500 for 3 days, with the water changed 4 times / day. After freeze-drying, the four-arm PEG-coumarin-epicatechin (PEG-COU-EGC, Mn ≈ 10,000) macromolecular monomer was obtained with a yield of 88%;

[0085] (7) Weigh 150 mg of the four-arm PEG-coumarin-epicatechin macromer and add it to 0.9 mL of PBS buffer. Ultrasonic vibration is used to dissolve it to form a viscous, transparent macromer solution.

[0086] (8) Add 0.1 mL of 50 mM FeCl3 solution, mix quickly and evenly, and let it stand. Gelation will begin within 15 seconds.

[0087] (9) A light yellow flexible hydrogel was formed within 2 min, and the coumarin bond could be induced to break under 320-365 nm light, reducing the gel strength by about 60%. The system achieved a high cross-linking rate through a four-arm structure and high epicatechin density, and the functionalization rate of the main chain end was controlled to 95%.

[0088] Example 3

[0089] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0090] (1) Thymine-1-ethanol (5.0 g, 35 mmol) was weighed and dissolved in 100 mL of anhydrous DMF. 4-bromobutyric acid (5.3 mL, 46 mmol) and potassium carbonate (7.0 g, 50.7 mmol) were added and stirred at room temperature under nitrogen for 24 h. The reaction solution was poured into 300 mL of ice water for precipitation to form a milky white suspension. The suspension was filtered, washed with water, and then vacuum dried to obtain a light yellow solid product, i.e., thymine butyrate intermediate (THY-COOH), with a yield of 85%.

[0091] (2) THY-COOH (2.5 g, about 8.0 mmol) obtained in step (1) and tannic acid (4.2 g, 6.0 mmol) were dissolved in 50 mL of anhydrous DMF; EDC·HCl (3.1 g, 16.0 mmol), NHS (1.84 g, 16.0 mmol) and triethylamine (2.5 mL, 18.0 mmol) were added to the reaction solution in sequence, and the mixture was stirred at room temperature for 24 h under light-shielding conditions; after the reaction was completed, the solvent was removed by rotary evaporation, and the resulting viscous orange intermediate was purified by silica gel column chromatography (DCM / MeOH = 30:1) to obtain a thymine-tannic acid ester coupling intermediate (THY-TA, THY represents a thymine structure, and TA represents a tannic acid derivative structure);

[0092] (3) Pluronic F127-NH2 (Mn ≈ 12,600, 10 g, approximately 0.8 mmol terminal amino group) was weighed and dissolved in 100 mL of anhydrous DMSO. Magnetic stirring was used to assist dissolution to obtain a transparent and uniform Pluronic-NH2 solution.

[0093] (4) The THY-TA intermediate (1.2 g, about 2.0 mmol acid groups) obtained in step (2) was dissolved in 20 mL of DMF, and HBTU (0.76 g, 2.0 mmol) and DIPEA (0.35 mL, 2.0 mmol) were added to activate the reaction for 10 min; the above solution was slowly added dropwise to the Pluronic-NH2 solution in step (3), and the reaction was continued under stirring at room temperature in the dark for 48 h;

[0094] (5) The reaction solution was diluted with an appropriate amount of DCM and washed three times with 1 M HCl, saturated NaHCO3, and saturated NaCl solutions to remove unreacted amine, acid, and residual coupling reagents. The organic phase was dried and the DCM was removed by rotary evaporation to obtain a yellow solid.

[0095] (6) The obtained yellow solid was dissolved in deionized water and dialyzed in deionized water using a dialysis bag with a MWCO of 3500 Da for 72 h, during which the water was changed 4 times / day; after the dialysis, the solid was freeze-dried for 24 h to obtain the Pluronic-THY-TA macromonomer with a yield of approximately 82%;

[0096] (7) Weigh 250 mg of Pluronic-THY-TA macromer and add it to 0.8 mL of PBS buffer. Shake well at 37°C to form an injectable transparent solution.

[0097] (8) Add 0.1 mL of a mixture containing horseradish peroxidase (HRP, 5 U / mL) and H2O2 (0.03 wt%) and stir slowly for 10 s;

[0098] (9) The system gels within 1 minute, producing a soft, sticky hydrogel that can adapt to the adhesion requirements of the skin surface; the material gradually turns into a liquid after being irradiated with ultraviolet light of a wavelength of 300-365nm for 15 minutes, achieving controllable debonding.

[0099] Example 4

[0100] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0101] (1) 4-Chlorobutyric acid (5.0 g, 48.3 mmol) and sodium carbonate (6.4 g, 60.0 mmol) were weighed and added to 100 mL of anhydrous acetonitrile, and the temperature was raised to reflux. Isoamylnitrosobutyrate (6.8 mL, 54.0 mmol) was added dropwise, and the mixture was refluxed for 4 h. After cooling to room temperature, the mixture was filtered and the solvent was removed by rotary evaporation to obtain a yellow viscous liquid. The intermediate O-acyloximebutyric acid (AO-COOH) was obtained by purification on a silica gel column (ethyl acetate / petroleum ether = 1:3) with a yield of 78%.

[0102] (2) AO-COOH (1.5 g, 8.2 mmol) obtained in step (1) and protocatechuic acid (PCA, 1.5 g, 8.7 mmol) were dissolved in 30 mL of anhydrous DMF, and EDC·HCl (3.1 g, 16.0 mmol), NHS (1.84 g, 16.0 mmol) and TEA (2.5 mL, 18.0 mmol) were added in sequence; the mixture was stirred and reacted at room temperature in the dark for 24 h, and the solvent was evaporated to obtain a viscous orange-yellow intermediate, which was purified by silica gel column to obtain the AO-PCA small molecule unit;

[0103] (3) Weigh amino-functionalized poly(ethylene glycol methacrylate) POEGMA-NH2 (Mn ≈ 20,000 Da, 5.0 g, approximately 0.25 mmol amino group) and dissolve it in 80 mL of anhydrous DMSO. Magnetic stirring was used to assist dissolution to form a transparent and uniform POEGMA-NH2 solution.

[0104] (4) The intermediate AO-PCA (1.0 g, 2.5 mmol) from step (2) was dissolved in 20 mL of DMF, and HBTU (0.95 g, 2.5 mmol) and DIPEA (0.43 mL, 2.5 mmol) were added. The mixture was activated at room temperature for 10 min. The mixture was slowly added dropwise to the POEGMA-NH2 solution and reacted at room temperature in the dark for 48 h.

[0105] (5) After the reaction is completed, the reaction solution is diluted with DCM, and the organic phase is washed three times with 1M HCl, saturated NaHCO3, and saturated NaCl solution in sequence; the organic phase is concentrated by rotary evaporation to obtain a light brown viscous product;

[0106] (6) The obtained product was dissolved in deionized water, transferred to a 3500 Da dialysis bag, and dialyzed in deionized water for 3 days, with the water changed 3-4 times per day; finally, freeze-dried for 24 h to obtain a light yellow powder macromonomer POEGMA-AO-PCA (Mn ≈ 20,000) with a yield of approximately 80%;

[0107] (7) Weigh 200 mg of POEGMA-AO-PCA macromer, add it to 0.9 mL of PBS buffer, and shake well to completely dissolve it to obtain a macromer solution;

[0108] (8) Add 0.1 mL of 5.4 wt% sodium periodate aqueous solution and mix immediately;

[0109] (9) The system begins to form a cross-linked network within 30 seconds of standing and completely gels within 1-2 minutes. The resulting gel has good responsiveness to 365 nm light, and the O-acyl oxime structure can break under short-wave light, causing the hydrogel to disintegrate. The network structure formed by catechol oxidative cross-linking gives it good wet adhesion.

[0110] Example 5

[0111] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0112] (1) 9-Anthraldehyde (5.0 g, 24 mmol) and maleic anhydride (3.5 g, 36 mmol) were weighed and dissolved in 50 mL of dichloromethane (DCM). A catalytic amount of DMAP (0.1 g) was added. After stirring at room temperature for 6 h, an equal volume of ice water was added for emulsification. The precipitate was filtered and dried to obtain yellow crystals. 30 mL of 1 M NaOH solution was added and refluxed for 2 h for complete hydrolysis. The precipitate was acidified (pH = 2) to obtain anthracenebutyric acid (Anth-COOH) intermediate with a yield of 78%.

[0113] (2) Anth-COOH (1.5 g, 5.5 mmol) obtained in step (1) and DHC (3,4-dihydroxycinnamic acid, 1.2 g, 6.1 mmol) were dissolved in 30 mL of anhydrous DMF; EDC·HCl (2.1 g, 11 mmol), NHS (1.3 g, 11 mmol) and TEA (1.6 mL, 11 mmol) were added; the mixture was stirred in the dark for 24 h, the solvent was evaporated and then purified on a silica gel column (DCM / MeOH = 30:1) to obtain an orange-yellow solid product Anth-DHC coupling unit, which was used for the next coupling step;

[0114] (3) Weigh hydroxyl-containing PCL-PEG-OH (3.0 g, ~0.75 mmol terminal hydroxyl group) and dissolve it in dry DCM. Add TEA (1.0 mL, 7.2 mmol) and p-toluenesulfonyl chloride (TsCl, 0.8 g, 4.2 mmol) for terminal activation. After reacting in an ice bath for 24 h, add excess concentrated ammonia (or saturated NH4Cl solution) and react for 48 h. DCM extraction, purification, and drying give amino-functionalized PCL-PEG-NH2 block copolymer.

[0115] (4) Weigh the intermediate Anth-DHC (1.0 g, about 2.0 mmol) from step (2), dissolve it in 10 mL of DMF, add HBTU (0.76 g, 2.0 mmol) and DIPEA (0.35 mL, 2.0 mmol) and activate it for 10 min; slowly add it to the PCL-PEG-NH2 (2.0 g, about 0.5 mmol) solution from step (3), and react at room temperature in the dark for 48 h;

[0116] (5) The reaction solution was diluted with DCM and washed three times with 1 M HCl, saturated NaHCO3, and saturated NaCl in sequence. The organic phase was concentrated by rotary evaporation to obtain an orange-yellow sticky solid. The solid was dissolved in deionized water and dialyzed in a MWCO 3500 Da dialysis bag for 72 h, with the water changed 3-4 times per day. Finally, the solid was freeze-dried to obtain the target product PCL-PEG-Anth-DHC macromonomer (anthracene photosensitizing group + catecholamine) with a yield of approximately 82%.

[0117] (6) Dissolve 200 mg of PCL-PEG-Anth-DHC macromer in 0.9 mL of PBS buffer (pH 7.2) and sonicate until completely dissolved;

[0118] (7) Add 0.1 mL of 50 mM FeCl3 solution and mix rapidly. The system begins to become viscous within 30 seconds and gelation is completed within 2 minutes, forming an orange hydrogel that is stable at room temperature.

[0119] (8) After irradiation with 365 nm light for 10 min, the hydrogel structure showed obvious deconstruction, and the gel modulus decreased by 70%. The gel end modification rate was 93%, and the cross-linking density was high, making it suitable for use as a temporary adhesion layer at the interface of flexible electronic packaging.

[0120] Example 6

[0121] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0122] (1) Weigh 4-hydroxyphenylacetic acid ethyl ester (6.0 g, 36.4 mmol) and dissolve it in 100 mL of anhydrous DMF. Add nitric acid (70%, 12 mL) and slowly dropwise add it in an ice bath. Control the reaction temperature not to exceed 5°C. Continue the reaction for 1 hour and then heat it to room temperature and stir for 3 hours to obtain crude o-nitrobenzyl ethyl ester (intermediate 1). Concentrate it by rotary evaporation and recrystallize it from ethyl acetate. Intermediate 1 (3.0 g, 14 mmol) and protocatechuic acid (PCA, 2.2 g, 14.6 mmol) were co-dissolved in DMF (30 mL). EDC·HCl (2.9 g, 15 mmol), NHS (1.7 g, 15 mmol) and triethylamine (2.3 mL, 16.5 mmol) were added and reacted at room temperature for 24 hours. After rotary evaporation, column chromatography purification was performed to obtain the photosensitive adhesion small molecule oNB-PCA intermediate with a yield of about 72%.

[0123] (2) Weigh the hydroxyl-terminated PLGA-PEG-OH (Mn≈3000-5000Da, 5.0g, about 1mmol), dissolve it in 100mL of anhydrous DCM, add triethylamine (2.5mL, 18mmol) and p-toluenesulfonyl chloride (1.9g, 10mmol), and react in an ice bath for 24h to generate PLGA-PEG-OTs activated ends; the reaction solution is washed with NaHCO3 saturated water, concentrated, dissolved in concentrated ammonia (NH3·H2O), stirred at room temperature for 48h, introduced amino groups, extracted, and dried to obtain PLGA-PEG-NH2 block copolymer with a yield of about 85%;

[0124] (3) oNB-PCA (1.0 g, 2.3 mmol) obtained in step (1) was dissolved in 15 mL of anhydrous DMF, HBTU (0.87 g, 2.3 mmol) and DIPEA (0.4 mL, 2.3 mmol) were added, and activated for 10 min; the mixture was slowly added dropwise to the PLGA-PEG-NH2 (2.0 g, approximately 0.4 mmol) solution prepared in step (2), and stirred at room temperature in the dark for 48 h;

[0125] (4) The reaction solution was diluted with DCM and washed with 1 M HCl, saturated NaHCO3, and saturated NaCl solutions in sequence. After separation, the solution was dried and concentrated by rotary evaporation to obtain a viscous yellow product. The product was dissolved in deionized water and transferred to a dialysis bag with a MWCO of 3500 Da for 3 days, with the water changed 3 times a day. Finally, it was freeze-dried to obtain the target product PLGA-PEG-oNB-PCA macromonomer (Mn≈8000, PLGA:PEG:PLGA≈3:2:3) with a yield of about 78%.

[0126] (5) Weigh 250 mg of PLGA-PEG-oNB-PCA macromer, dissolve it in 0.9 mL of PBS buffer, and shake at 37°C to form a transparent viscous solution;

[0127] (6) Add 0.1 mL of 5.0 wt% sodium periodate aqueous solution and immediately vortex mix. The system begins to gel;

[0128] (7) A light brown, flexible hydrogel was formed within 1.5 min, showing good formability and self-supporting ability. Under 365 nm ultraviolet light irradiation for 5 min, the gel volume was observed to shrink significantly, and after 10 min, it turned into a sol state, showing excellent light-controlled degradation performance.

[0129] Example 7

[0130] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0131] (1) 4-Hydroxycoumarin (6.0 g, 33.3 mmol) was weighed and dissolved in 100 mL of anhydrous DMF. 4-Bromobutyric acid (4.5 mL, 39.6 mmol) and potassium carbonate (6.0 g, 43.5 mmol) were added and reacted at room temperature under nitrogen for 24 h. The reaction solution was poured into 300 mL of ice water for precipitation, filtered, and dried to obtain a light yellow solid COU-C4-COOH with a yield of 88%.

[0132] (2) COU-C4-COOH (2.5 g, 9.3 mmol) and dopamine hydrochloride (1.76 g, 9.3 mmol) were weighed and dissolved in 40 mL of anhydrous DMF. EDC·HCl (2.2 g, 11.5 mmol), NHS (1.3 g, 11.5 mmol) and TEA (2.0 mL, 14.5 mmol) were added. The mixture was stirred in the dark for 24 h. The solvent was evaporated and purified by silica gel column chromatography (DCM / MeOH = 20:1 to 10:1) to obtain a light orange solid COU-DA small molecule with a yield of about 70%;

[0133] (3) Pluronic F127 (Mn≈12,600 Da, 10 g, approximately 0.8 mmol terminal hydroxyl group) was weighed and dissolved in dry DCM (100 mL). TEA (2.2 mL, 16 mmol) and methanesulfonyl chloride (1.5 mL, 19 mmol) were added and reacted in an ice bath for 24 h to generate Pluronic-OSO2CH3. The reaction solution was washed (1N HCl, saturated NaHCO3, NaCl), dried and concentrated, and the intermediate was dissolved in concentrated ammonia and reacted at room temperature for 48 h to introduce the amino terminus to obtain Pluronic-NH2 with a yield of approximately 85%.

[0134] (4) COU-DA (0.75 g, about 1.6 mmol) synthesized in step (2) was dissolved in 15 mL of anhydrous DMF, and HBTU (0.6 g, 1.6 mmol) and DIPEA (0.28 mL, 1.6 mmol) were added for pre-activation for 10 min; the mixture was slowly added to a solution of Pluronic-NH2 (2.0 g, about 0.16 mmol), and the mixture was reacted at room temperature for 48 h in the dark.

[0135] (5) The reaction solution was diluted with DCM, washed sequentially with 1 M HCl, saturated NaHCO3, and saturated NaCl, separated, and dried; the concentrated product was dissolved in deionized water and transferred to a dialysis bag with a MWCO of 3500 Da for 3 days, with the water changed 3-4 times per day; finally, the product was freeze-dried to obtain the target product Pluronic-COU-DA macromonomer (Mn ≈ 12,600) with a yield of approximately 80%;

[0136] (6) Weigh 200 mg of Pluronic-COU-DA macromer and add it to 0.9 mL of cold PBS buffer (4°C). Vortex and mix at low temperature to form a low-temperature injectable transparent liquid.

[0137] (7) Rapidly add 0.1 mL of 0.1 M FeCl3 solution, mix for 10 seconds, and place at room temperature (25°C) for 30 seconds before gelation begins.

[0138] (8) A gel is formed within 1 minute, maintaining good shear-thinning properties. After irradiation with 365 nm ultraviolet light for 15 minutes, the gel fluidity is significantly enhanced, and controllable debonding induced by light in vitro can be achieved in application scenarios.

[0139] Example 8

[0140] The preparation method of the photodegradable hydrogel specifically comprises the following steps:

[0141] (1) The terminal hydroxyl groups of PLGA-PEG-PLGA triblock copolymer (PLGA 3000-PEG 2000-PLGA 3000, 10.00 g) were converted to amino groups: dissolved in dry THF (100 mL), methanesulfonyl chloride (1.50 mL, 19.4 mmol) and TEA (2.00 mL, 14.4 mmol) were added, and the mixture was reacted in an ice bath for 2 h. Ammonia water (30%, 50 mL) was added, and the mixture was stirred for 24 h to obtain PLGA-PEG-PLGA-NH2 with a yield of 92%;

[0142] (2) o-Nitrobenzyl acid (2.30 g, 12.5 mmol) and protocatechuic acid (2.10 g, 13.0 mmol) were reacted in DMF in the presence of EDC / NHS (12.5 mmol each) for 24 h to obtain intermediate E;

[0143] (3) Intermediate E (2.00 g) was reacted with PLGA-PEG-PLGA-NH2 (10.00 g) in the presence of HBTU (3.2 mmol) and DIPEA (0.56 mL) for 48 h. The product was dialyzed (MWCO 10,000) and freeze-dried to obtain the PLGA-PEG-PLGA-AO-EGC (AO is a photocleavable structure and EGC is a catechin group) macromonomer.

[0144] (4) Weigh 300 mg of PLGA-PEG-PLGA-AO-EGC macromer, add it to 0.9 mL of PBS buffer (pH 7.0), and shake it thoroughly at 37°C to dissolve it;

[0145] (5) Add 0.1 mL of 5.4 wt% sodium periodate aqueous solution and gently mix at room temperature. The system will gel within 15 s.

[0146] (6) The obtained hydrogel is light yellow and transparent, and its structure is formed within 30 seconds. It can be used as a hydrogel adhesive on the tissue surface. After irradiation within the wavelength range of 300-400nm for 10 minutes, its cross-linked network structure can be controllably broken, and the colloid turns into liquid, verifying its potential application in the field of on-demand debonding.

[0147] Performance Testing

[0148] 1. Gel light rheology test

[0149] Based on Example 1, the gel was irradiated with UV light, and the gel state before and after irradiation was photographed. The photos of the gel in different states are summarized as follows: Figure 2 shown.

[0150] Depend on Figure 2 It can be seen that the gel in the glass bottle can be transformed into a fluid sol state after being irradiated with ultraviolet light for about 20 minutes, indicating the ultraviolet light responsive phase transition ability of the gel.

[0151] 2. Gel rheology test

[0152] On the basis of Example 1, the gel was subjected to rheological testing. The specific process is as follows: the rheometer uses a quartz plate with a diameter of 20 mm and a light irradiation accessory connected. About 0.5 mL of the pre-gelled solution gel in step (2) is sucked out with a pipette and dropped onto the plate rheometer. The distance between the plates is then controlled to be 1 mm, and the edges are sealed with dimethyl silicone oil to prevent evaporation during the gel test. The specific test parameters of the instrument are: strain time scanning (f = 1 Hz, strain = 0.5%). After the scan lasts for 25 seconds to obtain relatively stable data results, the gel is illuminated with 365 nm ultraviolet light for 200 seconds. During this period, data collection is continued. The final results are as follows. Figure 3 shown.

[0153] Depend on Figure 3 It can be seen that within 20 seconds after the start of light irradiation, the storage modulus G', a physical quantity reflecting the solid properties of the gel, and the energy dissipation modulus G", a physical quantity reflecting the liquid properties of the gel, reversed. This proves from the rheological property level that the gel has gel-sol phase transition characteristics after ultraviolet light irradiation.

[0154] 3. Gel lap-shear adhesion test before and after illumination A

[0155] On the basis of Example 1, the gel was subjected to a lap-shear adhesion test before and after illumination. The specific process is as follows: the pre-gel solution in step (2) was evenly spread on the surface of a clean and dry glass sheet, and at the same time, a slight pressure was applied with another glass sheet to ensure that the interface was in complete contact, forming a sandwich structure; after standing for 30 minutes, it was observed that a stable adhesion interface was formed between the two pieces of glass through the gel, and after flipping one of the glass sheets, the other did not fall off, showing good adhesion ability. Subsequently, 365nm ultraviolet light was used to irradiate the surface of the gel, and the irradiation time was set to 2 minutes. The gel was observed to gradually transform from a gel state to a sol state, and the edges of the non-clamped glass sheets began to loosen and shrink. The adhesion force was then tested with an electronic universal testing machine, and the adhesion strength and interface toughness were calculated based on the adhesion area. The glass sheet was then replaced with a polystyrene plastic sheet and the PDMS silicone rubber sheet and the above operation was repeated. The final summary results are as follows Figure 4 (First three groups) shown.

[0156] Depend on Figure 4 It can be seen that the bonding strength of the gel between two identical substrates of the three different types listed can be controlled by light. After ultraviolet light exposure, the bonding strength decreases significantly.

[0157] 4. Gel lap-shear adhesion test B before and after illumination

[0158] On the basis of Example 1, the gel was subjected to a lap-shear adhesion test before and after illumination. The specific process is as follows: the pre-gel solution in step (2) was evenly spread on the surface of a clean and dry PDMS silicone rubber sheet, and at the same time, a piece of copper sheet was used to apply slight pressure to ensure that the interface was in complete contact, forming a sandwich structure; after standing for 30 minutes, it was observed that a stable adhesion interface was formed between the two different sheets through the gel, and after flipping one of the glass sheets, the other did not fall off, showing good adhesion ability. Subsequently, 365nm ultraviolet light was used to irradiate the gel surface through the transparent side of the PDMS silicone rubber sheet, and the irradiation time was set to 2 minutes. The gel was observed to gradually transform from a gel state to a sol state, and the edge of the PDMS silicone rubber sheet on the non-clamped side began to loosen and shrink; then an electronic universal testing machine was used to test the adhesion force and the adhesion strength and interface toughness were calculated based on the adhesion area. The copper sheet was then replaced with pigskin and the above operation was repeated. The final summary results are as follows Figure 4 (The last two groups) are shown.

[0159] Depend on Figure 4 It can be seen that the bonding strength of the gel between the two different types of substrates listed above can be controlled by light exposure. After ultraviolet light exposure, the bonding strength decreases significantly.

[0160] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photodegradable hydrogel, characterized in that: It is formed by polymerizing macromolecular monomers containing photo-controlled bond-breaking units; The macromonomer containing the light-controlled cleavage bond unit is composed of a polymer chain, a light-responsive cleavage functional group and a molecular fragment containing a catechol structure covalently connected through chemical bonds.

2. The photodegradable hydrogel according to claim 1, characterized in that: The polymer chain is at least one of polyethylene glycol, polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer, poly(polyethylene glycol methacrylate), polycaprolactone-polyethylene glycol block copolymer, poly(lactic acid-glycolic acid)-polyethylene glycol block copolymer and poly(lactic acid-glycolic acid)-polyethylene glycol-poly(lactic acid-glycolic acid) triblock copolymer.

3. A photodegradable hydrogel according to claim 1 or 2, characterized in that: The polymer chain is at least one of linear polyethylene glycol, three-arm polyethylene glycol, four-arm polyethylene glycol and eight-arm polyethylene glycol, and has a number average molecular weight of 1000-50000 Daltons.

4. The photodegradable hydrogel according to claim 1, characterized in that: The photoresponsive cleavage functional group is at least one of o-nitrobenzyl ester, coumarin, anthracene, thymine and O-acyl oxime.

5. The photodegradable hydrogel according to claim 1, characterized in that: The molecular fragment containing catechol structure is at least one of dopamine, catechin, epicatechin, protocatechuic acid, catecholamine and tannic acid.

6. A method for preparing the photodegradable hydrogel according to any one of claims 1 to 5, characterized in that: The specific steps include: (1) synthesizing an intermediate A containing a photoresponsive cleavage functional group; (2) coupling the intermediate A with a molecular fragment containing a catechol structure to obtain a photosensitive adhesion small molecule structural unit B; (3) coupling the photosensitive adhesive small molecule structural unit B with the polymer chain containing active functional groups in a solvent under the catalytic action of a condensation agent to obtain a macromolecular monomer containing a photo-controlled bond-breaking unit; (4) dissolving the macromonomer containing the photo-cleavable bond in a dispersion medium to obtain a macromonomer solution for later use; (5) dissolving the oxidant in water to obtain an oxidant aqueous solution; (6) Adding the oxidant aqueous solution to the macromonomer solution, mixing them evenly, and allowing them to stand, thereby obtaining the photodegradable hydrogel.

7. The method for preparing a photodegradable hydrogel according to claim 6, characterized in that: In step (3), the condensing agent is at least one of 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate / N,N-diisopropylethylamine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide, N,N'-dicyclohexylcarbodiimide / 1-hydroxybenzotriazole, 1,1'-carbonyldiimidazole and triphosgene; and the solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

8. The method for preparing a photodegradable hydrogel according to claim 6, characterized in that: In step (4), the dispersion medium is 10 mM PBS buffer solution containing 0.15 M NaCl and pH 7.4, physiological saline or deionized water; and the mass concentration of the macromonomer solution is 10%-60%.

9. The method for preparing a photodegradable hydrogel according to claim 6, wherein: In step (5), the oxidant is sodium periodate, ferric chloride or H2O2 / HRP; the mass concentration of the oxidant aqueous solution is 0.5%-10%; In step (6), the volume ratio of the macromonomer solution to the oxidant aqueous solution is 1:(1-9); and the mixing is carried out by vortex oscillation or gentle stirring.

10. Use of the photodegradable hydrogel according to any one of claims 1 to 5 or the photodegradable hydrogel prepared by the preparation method according to any one of claims 6 to 9 in the preparation of drug carriers, cell carriers, biological tissue sealants, brain-computer interfaces and flexible electronic device adhesives.

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