Composite tissue adhesives and their applications

Abstract

This invention relates to a composite tissue adhesive and its application in hemostasis, sterilization, and wound healing promotion. The adhesive comprises component A and component B. Component A includes: methacrylic anhydride-modified gelatin, dodecaldehyde-modified chitosan, polycaprolactone / methacrylic anhydride-modified gelatin blended nanofibers, a photosensitive crosslinking agent, and water. Component B is an aqueous solution of an amino crosslinking agent. In use, components A and B are mixed, injected into the wound, and irradiated with ultraviolet or blue light. The tissue adhesive of this invention is injected directly into the wound site in liquid form. Upon light irradiation, it forms a gel structure in situ with a strength comparable to that of skin, simultaneously providing hemostasis, sterilization, and wound healing promotion.

Description

Technical Field

[0001] This invention relates to the field of tissue adhesive technology, specifically to a composite tissue adhesive and its application in hemostasis, sterilization, and wound healing promotion. Background Technology

[0002] Tissue adhesives are primarily used as an alternative to surgical sutures and for joining living tissues. Based on their composition, tissue adhesives can be divided into three main categories: natural adhesives, synthetic adhesives, and semi-synthetic adhesives. Among them, a representative of semi-synthetic adhesives, "gelatin-resorcinol-formaldehyde (GRF) adhesive," mainly consists of two solutions: a gelatin-resorcinol solution and a formaldehyde-glutaraldehyde solution. Formaldehyde and glutaraldehyde react not only with gelatin and resorcinol but also with amino groups in the tissue, thus creating adhesion between the gel and the tissue. Although GRF adhesives have extremely strong adhesive strength, they have poor in vivo degradation. Histological staining has revealed excessive proliferation of fibroblasts after using GRF adhesives, and they do not accelerate wound healing, even delaying it. Furthermore, GRF adhesives have poor hemostatic and clotting abilities and lack antibacterial properties. If the wound is not disinfected, the tissue adhesion can cause serious wound infection, endangering the patient's life. In addition, the mutagenicity and potential carcinogenicity of formaldehyde and resorcinol in GRF have been widely controversial since their application.

[0003] Significant bleeding and wound infection following tissue trauma are major risk factors for personal injury and death. Therefore, there is an urgent need for first-aid supplies capable of closing wounds and effectively controlling bleeding and infection. Existing tissue adhesives can adhere to tissue surfaces and achieve rapid wound closure, but most of them have only limited hemostatic and antibacterial capabilities, making them unsuitable as first-aid tissue adhesives. In current research, tissue adhesives are all gel-like or solid-like, lacking the conditions to induce cell adhesion and infiltration, and thus have little or no ability to promote wound healing; furthermore, adhesives with poor degradability may inhibit wound healing.

[0004] Matching the mechanical strength of tissue adhesives with the strength of the surrounding tissues is crucial. A mismatch between the adhesive hardness and the surrounding tissues can lead to inflammatory reactions and various complications at the wound site. On the other hand, matching the hardness of the implant with the surrounding tissues will encourage cells to carry out various repair behaviors. Therefore, for various types of wounds, such as ordinary skin trauma, skin plus bone or cartilage damage, controllable and adjustable mechanical strength is essential for tissue adhesives.

[0005] Furthermore, after acute treatment of a wound with tissue adhesive, some foreign body fragments often remain inside the wound. Therefore, a second surgery is often required to remove the foreign body. If the adhesive is removed or the surrounding tissue is operated on, it will cause secondary harm to the patient. If the tissue adhesive has self-healing function, the surgery can be performed on the adhesive, and the tissue adhesive will heal on its own without causing any harm to the patient.

[0006] To address the aforementioned problems, this invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a composite tissue adhesive to solve problems related to rapid hemostasis, sterilization, and promotion of wound self-healing. To this end, this invention provides the following technical solution.

[0008] On one hand, the present invention provides a composite tissue adhesive, comprising component A and component B. By weight, component A comprises: 5-10 parts of methacrylic anhydride gelatin, 5-20 parts of dodecyl-modified chitosan, 5-20 parts of short nanofibers blended with polycaprolactone / methacrylic anhydride gelatin, 1-5 parts of photosensitive crosslinking agent, and the balance being water, with the sum of all components being 100 parts; component B is an aqueous solution of an amino crosslinking agent.

[0009] Preferably, the composite tissue adhesive comprises component A and component B. By weight, component A comprises: 5-10 parts of methacrylic anhydride gelatin, 10-20 parts of dodecyl-modified chitosan, 10-20 parts of short nanofibers blended with polycaprolactone / methacrylic anhydride gelatin, 1-5 parts of photosensitive crosslinking agent, and the balance being water, with the sum of all components being 100 parts; component B is an aqueous solution of an amino crosslinking agent.

[0010] In this invention, the amino crosslinking agent is a crosslinking agent that can undergo a crosslinking reaction with amino groups.

[0011] Methacrylic anhydride-modified gelatin (GelMA), prepared from methacrylic anhydride (MA) and gelatin, is a photosensitive bio-hydrogel raw material. This material exhibits excellent biocompatibility and can undergo photo-excited cross-linking reactions to form a three-dimensional structure with sufficient strength suitable for cell growth and differentiation.

[0012] Furthermore, the mass ratio of component A to component B is (1:10) to (10:1), preferably (1:2) to (2:1).

[0013] Furthermore, the photosensitive crosslinking agent can initiate free radical polymerization of methacrylic acid groups and is selected from 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (I2959) or phenyl-2,4,6-trimethylbenzoyl lithium phosphite (LAP); the amino crosslinking agent is a four-arm polyethylene glycol aldehyde group, and the mass concentration of the aqueous solution of the amino crosslinking agent is 0.01-0.1 g / mL, preferably 0.01-0.05 g / mL.

[0014] The structural formula of the four-armed polyethylene glycol aldehyde group is:

[0015]

[0016] Furthermore, the grafting degree of methacrylic anhydride in the methacrylic anhydride-modified gelatin is 60-80%.

[0017] The grafting degree refers to the proportion of grafted points on the methacrylic anhydride gelatin backbone to the total number of graftable points.

[0018] Furthermore, the length of the polycaprolactone / methacrylic anhydride gelatin blended nanofibers is 50–100 μm.

[0019] This invention provides a method for preparing methacrylic anhydride-modified gelatin, comprising the following steps:

[0020] Gelatin is added to a buffer solution, heated and stirred until the solution is clear, then methacrylic anhydride is added dropwise, and stirring is continued to allow the methacrylic anhydride and gelatin to react. Once the reaction is complete, the resulting reaction mixture is dialyzed and freeze-dried to obtain the final product.

[0021] Furthermore, the buffer solution is a phosphate solution (PBS).

[0022] Furthermore, the heating temperature is 25–70°C, preferably 45–55°C.

[0023] Furthermore, the dropping rate of the methacrylic anhydride is 0.4–0.6 mL / min.

[0024] Furthermore, the reaction time is 2 to 4 hours.

[0025] Furthermore, the specific steps to terminate the reaction include: adding a PBS solution at 40°C to the reaction system and continuously stirring, wherein the volume of the added PBS solution is at least four times the volume of the reaction system solution.

[0026] Furthermore, the freeze-drying time is 2 to 3 days, and the freeze-drying temperature is -20 to -10°C.

[0027] Furthermore, the volume ratio of the methacrylic anhydride to the mass ratio of the gelatin is (0.5-1) mL: 1 g.

[0028] This invention provides a method for preparing dodecyl-modified chitosan (CSD), comprising the following steps:

[0029] Chitosan is dissolved in acetic acid at room temperature and diluted with ethanol. NaOH is added to adjust the pH to 5-6. Dodecyl aldehyde and excess sodium cyanoborohydride are added and stirred to allow dodecyl aldehyde to react with chitosan. After the reaction is complete, the pH of the solution is adjusted to neutral. The solution is then precipitated with ethanol and dried under vacuum to obtain the final product.

[0030] Furthermore, the reaction time is 23–25 hours.

[0031] Furthermore, the chitosan is chitosan with a degree of deacetylation ≥ 85%. Chitosan has good biocompatibility, adhesion, degradability, antibacterial properties, and plasticity, and can promote wound healing and tissue regeneration.

[0032] Furthermore, the mass ratio of chitosan to dodecaaldehyde is (1:1) to (10:1), preferably (5:1) to (10:1).

[0033] This invention provides a method for preparing short nanofibers blended from polycaprolactone / methacrylic anhydride gelatin (PCL / GelMA), comprising the following steps:

[0034] A mixed spinning solution of polycaprolactone (PCL) and methacrylic anhydride gelatin (GelMA) was prepared, and a blended nanofiber membrane was obtained by electrospinning. The blended nanofiber membrane was then crushed in a cell wall breaker to obtain blended short nanofibers.

[0035] Further, the mass ratio of the polycaprolactone to the methacrylic anhydride gelatin is (0.2:1) to (5:1), preferably (0.5:1) to (1:1).

[0036] Furthermore, the nanofiber membrane is broken up in the blender for 10 to 30 minutes.

[0037] PCL possesses excellent biocompatibility and mechanical properties, enhancing the mechanical strength of tissue adhesives. The use of short nanofibers aims to induce cell migration and adhesion, thereby accelerating wound healing.

[0038] Furthermore, component A is protected from light before use to prevent the photosensitive crosslinking agent from becoming deactivated. The photosensitive crosslinking agent is a photoinitiator that undergoes a free radical polymerization reaction with the methacrylic anhydride (MA) groups on gelatin under light conditions, causing it to crosslink.

[0039] On the other hand, the present invention provides the application of the above-mentioned composite tissue adhesive in hemostasis, sterilization and wound healing promotion.

[0040] The specific method of use is as follows: Mix component A with component B, inject the mixture into the wound, and irradiate it with ultraviolet or blue light for 20 to 40 seconds.

[0041] Furthermore, when the photosensitive crosslinking agent is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, ultraviolet light irradiation is used, with an ultraviolet light wavelength of 360-380 nm; when the crosslinking agent is lithium phenyl-2,4,6-trimethylbenzoylphosphonate, blue light irradiation is used, with a blue light wavelength of 405 nm.

[0042] The beneficial effects of this invention are as follows:

[0043] (1) The photosensitive crosslinking agent introduced into the system can crosslink the methacrylic anhydride (MA) groups on the gelatin under light irradiation. The degree of crosslinking reaction can be controlled by controlling the light irradiation time, thereby controlling the mechanical strength of the tissue adhesive, better matching the mechanical strength of the injured surrounding tissue, and expanding the application range.

[0044] (2) Some of the aldehyde groups in the four-arm polyethylene glycol aldehyde group of the amino crosslinking agent can crosslink with the amino groups in GelMA and CSD, and the remaining aldehyde groups can combine with the amino groups on the injured tissue to form strong Schiff base bonds, thereby adhering the tissue. Furthermore, the degree of crosslinking can be controlled by controlling the light exposure time of the photosensitive crosslinking agent and / or the content of the amino crosslinking agent, thereby controlling the degradation time of the tissue adhesive.

[0045] (3) The system introduces dodecyl-modified chitosan, which has excellent antibacterial properties and the dodecyl group can anchor red blood cells to accelerate coagulation.

[0046] (4) PCL / GelMA blended nanofibers can provide adhesion sites for cells, accelerate cell infiltration and migration from the surrounding wound tissue to the tissue adhesive, and rapidly proliferate and differentiate in the tissue adhesive, accelerating the degradation of the tissue adhesive while promoting wound healing. After degradation, new skin is formed, and the composite of nanofibers improves the mechanical properties of the tissue adhesive.

[0047] (5) The tissue adhesive of the present invention is injected directly into the wound site in liquid form during use, and a gel structure with a strength equivalent to that of the skin can be formed in situ by light irradiation. During the formation process, the gel structure bonds tightly to the tissue around the wound, and the gel swells to absorb a large amount of blood flowing out of the wound, thus quickly stopping the bleeding. Chitosan destroys the membrane structure of bacteria, thus effectively killing bacteria.

[0048] (6) The tissue adhesive of the present invention has a self-healing function, and all components are biodegradable, which expands its application scope and application prospects. Furthermore, if a second surgery is required, it can be performed directly on the formed gel to avoid secondary damage. This is because the adhesive contains free aldehyde and amino groups, which will re-form Schiff base bonds a few minutes after being broken.

[0049] Terminology Definition

[0050] Unless otherwise specified, the term "water" in this invention refers to "deionized water".

[0051] Unless explicitly stated otherwise, all scopes referenced in this invention include end values.

[0052] All figures in this invention are approximate values, regardless of whether words such as "approximately" or "about" are used. The numerical values ​​may vary by 1%, 2%, 5%, 7%, 8%, 10%, etc. Whenever a number with a value of N is disclosed, any number having a value of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, or N+ / -10% will be explicitly disclosed, where "+ / -" indicates addition or subtraction, and the range between N-10% and N+10% is also disclosed.

[0053] Unless otherwise stated, the following definitions as used in this invention shall apply. For the purposes of this invention, chemical elements are consistent with the CAS version of the periodic table and the 75th edition of the *Handbook of Chemistry and Physics*, 1994. Furthermore, general principles of organic chemistry can be found in *Organic Chemistry*, Thomas Sorrell, University Science Books, Sausalito: 1999, and *March's Advanced Organic Chemistry* by Michael B. Smith and Jerry March, John Wiley & Sons, New York: 2007, the entire contents of which are incorporated herein by reference.

[0054] Unless otherwise defined, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although similar or equivalent methods and materials may be used in the implementation or testing of embodiments of this invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned in this invention are incorporated herein by reference in their entirety, except where specific paragraphs are cited. In case of any conflict, this specification and its included definitions shall prevail. Furthermore, materials, methods, and examples are illustrative only and are not intended to be limiting. Detailed Implementation

[0055] The following description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0056] The preparation method of the nanofibers made from the blend of methacrylic anhydride gelatin (GelMA), dodecyl-modified chitosan (CSD), and polycaprolactone / methacrylic anhydride gelatin (PCL / GelMA) used in the embodiments of the present invention is as follows.

[0057] 1. Preparation of methacrylic anhydride-modified gelatin (GelMA):

[0058] 1.0 g of gelatin was added to a three-necked flask containing 10.0 mL of PBS solution and heated to 50 °C with continuous stirring for 1 h. Once a pale yellow, clear solution was formed, 0.8 mL of methacrylic anhydride was slowly added dropwise to the stirred solution at a rate of 0.5 mL / min. The reaction was allowed to proceed for 3 h. Subsequently, 50 mL of PBS solution at 40 °C was added to the solution to stop the reaction, and stirring was continued for 15 min. The resulting solution was dialyzed against distilled water at 40 °C for one week (the dialysis bag had a molecular weight cutoff of 12000-14000 Da). After dialysis, the solution was freeze-dried for 3 days, finally yielding a white, foamy product, which was stored at -20 °C for later use.

[0059] 2. Preparation of dodecanal-modified chitosan (CSD):

[0060] At room temperature, 4 g of deacetylated chitosan was dissolved in 220 mL of acetic acid (0.2 M) and diluted with 150 mL of ethanol. The pH was then adjusted to 5.1 using 1 M NaOH, and 10 mL of a 0.05 g / mL solution of dodecaldehyde prepared in ethanol was added. Excess sodium cyanoborohydride was then added, and the reaction was continued at room temperature for 24 h. At the end of the reaction, the pH was adjusted to 7.0 using 1 M NaOH. The product was precipitated from the solution by adding excess ethanol, and thoroughly washed with ethanol to remove unreacted dodecaldehyde and sodium cyanoborohydride. The precipitate was then vacuum-dried at room temperature for later use.

[0061] 3. Preparation of short nanofibers blended with polycaprolactone / methacrylic anhydride gelatin (PCL / GelMA):

[0062] 50.0 mg PCL and 70.0 mg of GelMA prepared in step 1 above were dissolved in 2.0 mL of hexafluoroisopropanol (HFIP). The prepared solution was then poured into a syringe, which was placed into the pusher of an electrospinning machine. The needle was connected to a high-voltage power supply that was not turned on. A roller wrapped with aluminum foil was used as the nanofiber receiving device. The distance from the stainless steel needle to the collector was set to 12 cm, and the ambient humidity was 40% RH. During electrospinning, the voltage was kept constant at 10 kV and the flow rate at 1.0 mL / h to obtain a nanofiber membrane. The prepared nanofiber membrane was dried overnight at room temperature in a vacuum drying oven to remove residual HFIP. Subsequently, the nanofiber membrane and an appropriate amount of ethanol were placed in a high-speed blender and the blending time was controlled to be 20 min to obtain short nanofibers with a length of 50-100 μm. These were then freeze-dried to remove the ethanol for later use.

[0063] Example 1

[0064] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0065] GelMA, CSD, PCL / GelMA blended nanofibers, photosensitive crosslinking agent I2959, and water were stirred uniformly under light-protected conditions in a mass ratio of 10:5:10:1:74 to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0066] Example 2

[0067] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0068] GelMA, CSD, PCL / GelMA blended short nanofibers, photosensitive crosslinking agent I2959, and water were stirred uniformly under light-protected conditions in a mass ratio of 10:10:10:1:69 to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0069] Example 3

[0070] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0071] GelMA, CSD, PCL / GelMA blended short nanofibers, photosensitive crosslinking agent I2959, and water were stirred uniformly under light-protected conditions in a mass ratio of 5:20:10:1:64 to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0072] Example 4

[0073] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0074] GelMA, CSD, PCL / GelMA blended short nanofibers, photosensitive crosslinking agent I2959, and water were stirred evenly under light-protected conditions in a mass ratio of 10:10:5:5:70 to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0075] Example 5

[0076] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0077] GelMA, CSD, PCL / GelMA blended short nanofibers, photosensitive crosslinking agent I2959, and water were stirred uniformly under light-protected conditions in a mass ratio of 10:10:20:1:59 to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0078] Example 6

[0079] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 2:1.

[0080] The components A and B are the same as in Example 2.

[0081] Example 7

[0082] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:2.

[0083] The components A and B are the same as in Example 2.

[0084] Example 8

[0085] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0086] Component A is the same as in Example 2, and component B is a 0.05 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution.

[0087] Comparative Example 1

[0088] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0089] GelMA, PCL / GelMA blended short nanofibers, photosensitive crosslinking agent I2959, and water were mixed in a mass ratio of 10:10:1:79 under light-protected conditions to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0090] Comparative Example 2

[0091] The composite tissue adhesive provided in this embodiment includes component A and component B, wherein the mass ratio of component A to component B is 1:1.

[0092] GelMA, CSD, photosensitive crosslinking agent I2959, and water were mixed in a mass ratio of 10:10:1:79 under light-protected conditions to obtain component A. A 0.02 g / mL tetra-arm polyethylene glycol aldehyde aqueous solution was prepared to obtain component B.

[0093] Performance Testing and Evaluation

[0094] Components A and B obtained in the above examples and comparative examples were mixed to obtain a mixture. The hemostasis time, antibacterial properties, mechanical properties and adhesive strength of the mixture were tested. The test results are shown in Table 1.

[0095] (1) Hemostasis time

[0096] Inject the mixture into the wound of the mouse, irradiate with ultraviolet light (365nm) for 30s, and observe the hemostasis time, starting from the start of injection.

[0097] (2) Antibacterial properties

[0098] The mixture was injected into a circular mold with a diameter of 1 cm. After irradiation with ultraviolet light (365 nm) for 30 seconds, the mold was demolded and then placed in a container containing 1x10 5 In a culture dish of S. aureus (d = 5 cm), the bacteria in the culture medium were counted every 2 hours by measuring the OD value at a wavelength of 600 nm.

[0099] (3) Mechanical properties

[0100] The mixture was injected into a circular mold with a diameter of 1 cm, irradiated with ultraviolet light (365 nm) for 30 seconds, and then molded and demolded. Subsequently, the compression modulus was tested.

[0101] (4) Adhesion

[0102] The mixture was injected between two rectangular (3cm x 2cm) pieces of pigskin. After irradiation with ultraviolet light (365nm) for 30 seconds, the adhesive force of the tissue adhesive was measured using a universal tensile tester.

[0103] Table 1

[0104] serial number Hemostasis time (seconds) OD value Compression modulus (MPa) Adhesive strength (KPa) Example 1 30 0.97 48.3 5.325 Example 2 10 0.17 60.5 5.634 Example 3 8 0.15 64.1 5.423 Example 4 12 0.21 57.4 5.667 Example 5 11 0.19 110.7 5.744 Example 6 8 0.25 75.3 3.234 Example 7 12 0.16 80.3 5.946 Example 8 11 0.19 70.6 6.718 Comparative Example 1 385 2.51 40.1 4.857 Comparative Example 2 12 0.27 34.3 3.937

[0105] As shown in Table 1, the composite adhesive provided by this invention exhibits superior hemostatic, antibacterial, mechanical, and adhesive properties compared to the comparative examples. In Comparative Example 1, without the addition of CSD, the hemostatic time was 385 seconds, indicating that the blood did not coagulate spontaneously, and the antibacterial effect was poor. This suggests that chitosan plays a role in hemostasis and antibacterial activity within the system, with the dodecyl groups anchoring red blood cells and accelerating coagulation. In Comparative Example 2, without the addition of PCL / GelMA blended nanofibers, the tissue adhesive showed poor compressive modulus, indicating that the PCL / GelMA blended nanofibers can improve the mechanical properties of the tissue adhesive.

[0106] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite tissue adhesive, comprising component A and component B, characterized in that, By weight, component A comprises: 5-10 parts of methacrylic anhydride gelatin, 5-20 parts of dodecyl-modified chitosan, 5-20 parts of short nanofibers blended with polycaprolactone / methacrylic anhydride gelatin, 1-5 parts of photosensitive crosslinking agent, and the balance being water, with the sum of all components being 100 parts; component B is an aqueous solution of amino crosslinking agent.

2. The composite tissue adhesive according to claim 1, characterized in that, The mass ratio of component A to component B is (1:10) to (10:1).

3. The composite tissue adhesive according to claim 1, characterized in that, The photosensitive crosslinking agent is selected from 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone or lithium phenyl-2,4,6-trimethylbenzoylphosphonate; the amino crosslinking agent is a tetra-arm polyethylene glycol aldehyde, and the mass concentration of the aqueous solution of the amino crosslinking agent is 0.01-0.1 g / mL.

4. The composite tissue adhesive according to claim 1, characterized in that, The grafting degree of methacrylic anhydride in the methacrylic anhydride gelatin is 60-80%.

5. The composite tissue adhesive according to claim 1, characterized in that, The length of the polycaprolactone / methacrylic anhydride gelatin blended nanofibers is 50–100 μm.

6. The composite tissue adhesive according to claim 1, characterized in that, The preparation method of the dodecyl-modified chitosan includes: dissolving chitosan in acetic acid at room temperature, diluting it with ethanol, adding NaOH to adjust the pH to 5-6, adding dodecyl and excess sodium cyanoborohydride, stirring to allow dodecyl to react with chitosan, adjusting the pH of the solution to neutral after the reaction is complete, and obtaining the chitosan by ethanol precipitation and vacuum drying.

7. The composite tissue adhesive according to claim 6, characterized in that, The reaction time is 23-25 ​​hours, the chitosan is chitosan with a degree of deacetylation ≥85%, and the mass ratio of chitosan to dodecylaldehyde is (1:1) to (10:1).

8. The composite tissue adhesive according to claim 1, characterized in that, The method for preparing the polycaprolactone / methacrylic anhydride gelatin blended nanofibers includes: preparing a mixed spinning solution of polycaprolactone (PCL) and methacrylic anhydride gelatin (GelMA), obtaining a blended nanofiber membrane using electrospinning technology, and then crushing the blended nanofiber membrane in a cell wall breaker to obtain the blended nanofibers.

9. The composite tissue adhesive according to claim 8, characterized in that, The mass ratio of polycaprolactone to methacrylic anhydride gelatin is (0.2:1) to (5:1), and the nanofiber membrane is broken up in a cell wall blender for 10 to 30 minutes.

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