Multifunctional biological bonding hydrogel as well as preparation method and application thereof

Abstract

The invention provides multifunctional bioadhesive hydrogel as well as a preparation method and application thereof, and relates to the technical field of biomedical materials. The preparation method comprises the following steps: dissolving dopamine modified gelatin (DA-Gel), sulphobetaine methacrylate (SBMA), acrylic acid (AA) and perfluoroalkyl ethyl methacrylate (PFEMA) in a dimethyl sulfoxide (DMSO) solution, uniformly stirring, injecting into a mold, carrying out cross-linking polymerization by adopting electron beam radiation without adding a chemical cross-linking agent, and preparing a hydrophobic film by adjusting the radiation absorption dose (0-50 kGy) and the hydrophobic monomer content. The mechanical property, the adhesion strength and the swelling behavior of the hydrogel can be accurately regulated and controlled, and the hydrogel with a three-dimensional interpenetrating network structure is obtained. The hydrogel prepared by the process can form rapid and tough adhesion on the surface of a moist tissue, effectively seal a wound, resist swelling in a body fluid environment and promote tissue regeneration, and has a wide clinical application prospect in the fields of wound hemostasis, surgical incision closure, viscera perforation repair and the like.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, and in particular to a multifunctional bioadhesive hydrogel, its preparation method, and its application. Background Technology

[0002] Uncontrolled bleeding is a leading cause of death following trauma and surgery. Rapid hemostasis can significantly reduce mortality and improve patient outcomes. Surgical suturing is currently one of the most effective methods for managing emergency trauma and visceral injuries, but its successful implementation requires specialized surgeons, is complex and time-consuming, and can be accompanied by complications such as pain, fluid or gas leakage, limiting its success rate. These limitations highlight the urgent need to develop more effective hemostatic techniques and materials. Ideal hemostatic materials should possess rapid gelation, strong tissue adhesion, biocompatibility, biodegradability, and stability. Currently, commercially available tissue adhesives and sealants (such as fibrin glue, BioGlue, and cyanoacrylates) are widely used in clinical wound hemostasis, but shortcomings remain. For example, fibrin glue has insufficient tissue adhesion; while BioGlue and cyanoacrylates, although possessing strong adhesion, have impaired biocompatibility due to toxic aldehyde components or degradation byproducts, potentially triggering excessive inflammatory responses. Especially when used for internal organ applications such as aortic bleeding, surgical adhesives not only need strong wet tissue adhesion and excellent biocompatibility, but also need to have tough mechanical properties, high burst pressure resistance and excellent antibacterial activity in order to achieve rapid hemostasis and sealing and prevent bacterial infection.

[0003] Adhesive hydrogels have attracted widespread attention due to their strong tissue adhesion, good mechanical properties, excellent flexibility, biocompatibility, and biodegradability. However, the interfacial water layer on the tissue surface can hinder rapid and firm adhesion between the hydrogel and the tissue. Furthermore, hydrogels swell upon absorbing water, which may impair their durable adhesion to wounds and potentially cause secondary damage. Inspired by marine mussels, strong underwater adhesion can be achieved through dopamine groups, which can bind proteins to the substrate surface through hydrogen bonding, metal chelation, and other interactions. Dopamine also exhibits excellent antibacterial, antioxidant, anti-inflammatory, and biodegradable properties. Gelatin is known for its excellent biocompatibility and cost-effectiveness, and can be modified to introduce functional groups that impart additional functions. Therefore, modifying gelatin with dopamine to introduce catechol functional groups can enhance its mechanical properties and wet adhesion capabilities. Sulfobetaine methacrylate (SBMA) is a typical zwitterionic molecule containing sulfonic acid and quaternary ammonium groups, exhibiting good biocompatibility. Electrostatic interactions within the hydrogel network are considered an effective method to improve its anti-swelling properties in aqueous environments. The "lock-in" effect resulting from electrostatic interactions between zwitterionic groups has been used to develop highly stable hydrogel systems. Furthermore, introducing hydrophobic groups into hydrogel networks has proven to be an effective strategy for inhibiting water molecule diffusion, while also contributing to enhanced interfacial hydrophobicity. However, excessive hydrophobic components may hinder the migration of polymer chains to the interface, thereby weakening interfacial adhesion to biological tissues. Therefore, only an appropriate amount of hydrophobic groups can positively influence interfacial adhesion and anti-swelling ability. Acrylic acid (AA) contains highly reactive carbon-carbon double bonds, readily undergoing free radical reactions, thus increasing the mechanical strength and crosslinking density of the hydrogel.

[0004] Existing methods for preparing hydrogels are diverse, involving a combination of physical and chemical crosslinking, copolymerization of one or more monofunctional and multifunctional monomers, or crosslinking homopolymers or copolymers in solution. While traditional chemical crosslinking agents can enhance mechanical and thermal stability, their use raises concerns about potential toxicity, limited swelling capacity, and slow stimulus response. In recent years, there have been reports of hydrogel synthesis via radiation-induced polymerization and grafting. Radiation crosslinking is a widely used technique because it requires no chemical crosslinking agents. Furthermore, this modification can be completed in one step, making the conversion of biopolymers cost-effective, particularly suitable for biomedical end-use applications. This technique primarily relies on the generation of free radicals within the polymer upon exposure to high-energy radiation (ultraviolet, gamma rays, X-rays, or electron beams). The radiation effect (direct or indirect) depends on the polymer environment, such as dilute solution, concentrated solution, or solid state. Therefore, this method not only avoids the use of additional chemicals but also helps maintain the biocompatibility of the polymer.

[0005] Chinese patent CN113563591A discloses a wet adhesive hydrogel based on dopamine-modified gelatin and polyvinyl alcohol, and its preparation method. This method achieves a certain degree of wet adhesion by grafting dopamine onto gelatin chains and utilizing the reversible coordination of borax with polyvinyl alcohol and catechol groups to form a dynamic cross-linked network. However, its dynamic covalent network lacks stability under long-term immersion in body fluids, leading to significant swelling of the hydrogel, degradation of its mechanical properties, and decreased adhesion. Furthermore, the dynamic cross-linking points are prone to slippage under high-frequency stress, lacking adaptability to complex dynamic wound environments.

[0006] Chinese patent CN112007158B discloses a composite hydrogel dressing with antibacterial function. This dressing achieves its antibacterial properties by loading silver nanoparticles onto a chitosan / sodium alginate network through a blending process. However, its wet tissue adhesion mainly relies on the cationic electrostatic interaction of chitosan, resulting in limited adhesion strength (typically <30 kPa), making it difficult to effectively seal wounds in highly mobile areas or internal organs. Furthermore, the use of glutaraldehyde as a chemical cross-linking agent in its preparation process to enhance mechanical properties poses a potential risk of cytotoxicity, and its biocompatibility needs improvement.

[0007] In the field of bioadhesive hydrogel technology, current research largely focuses on optimizing single properties, such as improving initial adhesion or enhancing mechanical strength. However, integrated hydrogel materials that can simultaneously achieve multiple functions such as strong wet adhesion, high toughness, excellent anti-swelling properties, and antibacterial, anti-inflammatory, and healing-promoting effects, and can be prepared using simple and environmentally friendly processes, are still lacking. To overcome the aforementioned deficiencies in existing technologies, this invention aims to provide a multifunctional bioadhesive hydrogel constructed through a radiation crosslinking strategy. Summary of the Invention

[0008] This invention addresses the shortcomings of existing technologies, such as weak adhesion, easy swelling and failure, mismatched mechanical properties, limited functionality, and potential biotoxicity introduced by the use of chemical crosslinking agents in wet environments, by providing a multifunctional bioadhesive hydrogel prepared through a green radiation process. The technical problem this invention aims to solve is how to prepare an integrated hydrogel material with adjustable mechanical properties, strong wet adhesion, excellent anti-swelling properties, and multiple bioactivities in a one-step electron beam radiation copolymerization crosslinking method.

[0009] The objective of this invention can be achieved through the following technical solution: A multifunctional bioadhesive hydrogel prepared by radiation crosslinking, characterized in that the hydrogel is formed by a copolymerization and crosslinking reaction of dopamine-modified gelatin, sulfobetaine methacrylate, acrylic acid, and perfluoroalkyl ethyl methacrylate initiated by electron beam irradiation. It possesses a three-dimensional interpenetrating network structure, enabling rapid adhesion to moist tissue surfaces, resisting swelling under physiological fluid conditions, and providing continuous mechanical support, antibacterial properties, and promoting healing. This invention produces a product with excellent comprehensive performance and high biosafety. The preparation method requires no chemical crosslinking agent, is green and simple, has high production efficiency, and low cost. A method for preparing a multifunctional bioadhesive hydrogel prepared by radiation crosslinking includes the following steps: ① Preparation of dopamine-modified gelatin (DA-Gel): Gelatin was dissolved in phosphate buffer, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide were added to activate the carboxyl groups. The pH was adjusted to 5.0, and then dopamine hydrochloride was added. The reaction was carried out at room temperature in the dark for 24 hours. After the reaction was completed, the gelatin was purified by dialysis and freeze-dried to obtain DA-Gel.

[0010] ② Preparation of prepolymer solution: Dissolve the DA-Gel obtained in step ① together with sulfobetaine methacrylate, acrylic acid, and perfluoroalkyl ethyl methacrylate in a 30% (v / v) dimethyl sulfoxide aqueous solution and stir at room temperature for 3 hours to form a homogeneous and transparent prepolymer solution; wherein, the mass percentage of each component is: DA-Gel 8%, sulfobetaine methacrylate 5%, acrylic acid 10%, and perfluoroalkyl ethyl methacrylate 4%.

[0011] ③ Radiation crosslinking molding: The prepolymer obtained in step ② is injected into the mold and irradiated with an electron beam accelerator with an energy of 1 MeV and a radiation absorbed dose of 40 kGy to induce free radical polymerization and crosslinking reaction, forming a solid hydrogel in the mold.

[0012] ④ Post-processing and molding: Remove the hydrogel obtained in step ③ from the mold, soak it in deionized water to displace the residual solvent, and cut it into a specific shape as needed to obtain the multifunctional bioadhesive hydrogel (denoted as DSAF).

[0013] ⑤ Preparation of asymmetric adhesive patch: Contact one side of the hydrogel obtained in step ④ with a polyvinyl alcohol solution, and form a non-adhesive polyvinyl alcohol backing layer on the surface by cyclic freezing treatment, thereby obtaining a ready-to-use hydrogel patch with strong adhesion on one side and non-adhesion on the other side.

[0014] Furthermore, the degree of substitution of the dopamine-modified gelatin can be controlled by adjusting the ratio of dopamine to gelatin.

[0015] Furthermore, the volume concentration of the dimethyl sulfoxide aqueous solution in the prepolymer solution can be adjusted between 25% and 35% to optimize solubility and subsequent radiation crosslinking efficiency.

[0016] Furthermore, the absorbed dose of the electron beam radiation can be adjusted within the range of 20 kGy to 50 kGy by changing the irradiation time, so as to precisely control the crosslinking density of the hydrogel, thereby regulating its swelling rate, mechanical strength and adhesion properties. The preferred absorbed dose is 40 kGy.

[0017] Furthermore, the mass percentage of the perfluoroalkyl ethyl methacrylate in the prepolymer solution can be adjusted within the range of 2% to 6% to regulate the hydrophobicity and interfacial water displacement capacity of the hydrogel network, thereby optimizing its anti-swelling properties and wet adhesion strength. A preferred content is 4%.

[0018] Furthermore, after preparation, the hydrogel can be used after swelling and equilibration in phosphate buffer, with an equilibrium swelling ratio as low as 10.30 ± 0.50%.

[0019] Furthermore, the hydrogel exhibits an adhesion strength of 93.41 ± 3.07 kPa to moist pigskin and an interfacial toughness of 400.8 ± 22.53 J / m. - ², with a burst pressure resistance of up to 341.07 ± 9.34 mmHg.

[0020] Furthermore, the hydrogel exhibits a bactericidal rate of over 99% against Escherichia coli and Staphylococcus aureus in vitro, and also demonstrates a significant ability to scavenge hydrogen peroxide and DPPH free radicals.

[0021] Furthermore, the hydrogel is biodegradable in vivo, and after being implanted subcutaneously in rats for 28 days, it still maintains structural integrity, and no severe inflammatory response or systemic toxicity was observed in the surrounding tissues.

[0022] The technical problem to be solved by this invention is to provide a multifunctional bioadhesive hydrogel that is simple to prepare, requires no chemical cross-linking agents, and is environmentally friendly. This hydrogel needs to overcome the problems of insufficient wet adhesion, easy swelling leading to adhesion failure, mismatch between mechanical properties and soft tissues, and limited functionality in existing technologies. It aims to achieve rapid, strong, and long-lasting adhesion and sealing of various tissues (such as skin, heart, liver, stomach, and intestines) in a moist, dynamic physiological environment. Simultaneously, it possesses multiple functions including excellent biocompatibility, controllable degradation, antibacterial properties, antioxidant properties, and promotion of tissue regeneration, providing a novel and effective solution for complex surgical procedures and wound repair.

[0023] This method has the following advantages compared to existing technologies: 1. The hydrogel prepared by this invention achieves an organic combination of strong wet tissue adhesion, high toughness, low swelling and multiple biological functions (antibacterial, antioxidant and healing promotion), which can effectively seal dynamic and moist wounds, such as wounds in active areas and visceral perforations.

[0024] 2. The entire preparation process requires no addition of any chemical crosslinking agents, initiators, or catalysts, avoiding toxic chemical residues, ensuring high biosafety of the materials, and making the process green and environmentally friendly.

[0025] 3. The preparation process is carried out under mild reaction conditions and can be completed in a room temperature aqueous solution environment through one-step radiation. It is simple to operate, easy to achieve large-scale and continuous production, and the cost is controllable.

[0026] 4. By adjusting the two key parameters of radiation dose and hydrophobic monomer content, the mechanical properties, adhesion strength and degradation behavior of hydrogels can be linearly and precisely controlled to meet the personalized needs of different clinical applications.

[0027] 5. Combined with a polyvinyl alcohol backing layer, it is easy to construct asymmetric adhesive patches, which can effectively prevent postoperative tissue adhesion while achieving reliable wound sealing, thus expanding its application value in intra-abdominal surgery and other scenarios. Attached Figure Description

[0028] Figure 1 It's DA-Gel. 1 H nuclear magnetic resonance spectrum.

[0029] Figure 2 These are the Fourier transform infrared spectra of DSAF colloidal gels and their precursors.

[0030] Figure 3 These are the mechanical property test data for DSAF hydrogels prepared under different irradiation doses. Among them, Figure 3 Figure (a) shows the tensile shear test of DSAF hydrogel on pig skin under different irradiation doses (n=3). Figure 3 Figure (b) shows the swelling behavior of DSAF hydrogels under different irradiation doses (n=3); Figure 3 Figure (c) shows the elongation at break of DSAF hydrogel under different irradiation doses (n=3).

[0031] Figure 4 These are the mechanical property test data for DSAF hydrogels at different concentrations. Figure 4 Figure (a) shows the swelling characteristics of DSAF and DSA hydrogels (n=3); Figure 4 Figure (b) shows the elongation at break (n=3) of DSAF and DSA hydrogels.

[0032] Figure 5These are the viscosity test data for DSAF hydrogel. Among them, Figure 5 Figure (a) shows the adhesion strength test between DSAF hydrogel and pig skin (n=3); Figure 5 Figures (b) and (c) show the 180° peel adhesion strength test of the DSAF hydrogel (n=3). Figure 5 Figure (d) shows a burst pressure test (n=3) of pig skin using DSAF hydrogel with a 5 mm diameter incision.

[0033] Figure 6 Figure (a) in the image is a photograph of the DSAF hydrogel; Figure 6 Figure (b) shows the hemolysis rate (n=3) corresponding to DSAF hydrogel.

[0034] Figure 7 Figure (a) shows the MTT assay of L929 cells cultured in DSAF hydrogel extract (n=3). Figure 7 Figure (b) shows the live / dead staining of L929 cells cultured with DSAF hydrogel extract (n=3).

[0035] Figure 8 Figure (a) shows the bacterial survival rate of Escherichia coli and Staphylococcus aureus colonies on agar plates after different hydrogel treatments (n=3). Figure 8 Photographs and scanning electron microscope (SEM) images of the data corresponding to Figure (b) in Figure (a) (n=3).

[0036] Figure 9 H&E staining images of visceral tissues, including the heart, liver, spleen, lungs, and kidneys, isolated from normal mice and surgical mice treated with subcutaneous DSAF hydrogel. Detailed Implementation

[0037] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0038] Example 1: 4.0 g of gelatin was weighed and dissolved in 100 mL of phosphate buffer (pH=7.4). Then, 1.0 g of EDC and 0.6 g of NHS were added to the solution, and the pH of the mixture was adjusted to 5.0. The mixture was then magnetically stirred for 30 minutes for activation. Next, 2.0 g of dopamine hydrochloride was added, and the reaction was carried out at room temperature in the dark for 24 hours, maintaining the pH between 5.0 and 6.0. After the reaction, the product was purified by dialysis using a dialysis bag with a molecular weight cutoff of 3500 Da, followed by freeze-drying for 24 hours to obtain dopamine-modified gelatin (DA-Gel). NMR spectroscopy confirmed the successful modification of DA-Gel. Weigh 0.8 g of the prepared DA-Gel, 0.5 g of sulfobetaine methacrylate (SBMA), 1.0 g of acrylic acid (AA), and 0.4 g of perfluoroalkyl ethyl methacrylate (PFEMA), and add them together to a beaker containing 30% dimethyl sulfoxide (DMSO) aqueous solution (total volume controlled to 10 mL). Stir at room temperature for 3 hours until a homogeneous and transparent prepolymer solution is formed. Inject this prepolymer solution into a glass mold and irradiate it using an electron beam accelerator with an energy of 1 MeV and a radiation absorbed dose set to 40 kGy. After irradiation, remove the formed pale yellow transparent hydrogel from the mold and immerse it in deionized water for 48 hours, changing the water every 8 hours to completely replace the residual DMSO, thus obtaining a multifunctional bioadhesive hydrogel, denoted as DSAF-1. Then, Fourier transform infrared spectroscopy was performed on the various components of the hydrogel and the hydrophobic monomers at different concentrations, and the results successfully proved the synthesis of the hydrogel. In addition, tests showed that the hydrogel had an adhesion strength of 93.41 ± 3.07 kPa to moist pigskin, a 24-hour equilibrium swelling ratio of 10.30 ± 0.50%, a fracture strain of 736.33%, and a fracture stress of 46.75 kPa.

[0039] Example 2: The synthesis steps of DA-Gel were exactly the same as in Example 1. Equal masses of DA-Gel (0.8 g), SBMA (0.5 g), AA (1.0 g), and PFEMA (0.4 g) were weighed and dissolved in a 30% DMSO aqueous solution to prepare a prepolymer solution. After injecting the prepolymer solution into a mold, it was irradiated using the same 1 MeV electron beam accelerator, but the absorbed radiation dose was adjusted to 25 kGy. The subsequent hydrogel removal and washing steps were the same as in Example 1, and the resulting hydrogel was designated DSAF-2. The hydrogel network prepared under these conditions had a relatively low degree of cross-linking, with an adhesion strength of 78.15 ± 4.21 kPa, an equilibrium swelling ratio that increased to 26.86 ± 1.98%, and an increase in fracture strain but a slight decrease in fracture stress. This demonstrates that the performance of the hydrogel can be controlled by adjusting the radiation dose, ranging from a softer, highly swollen state to a tougher, less swollen state.

[0040] Example 3: The synthesis steps of DA-Gel were the same as in Example 1. The amount of the hydrophobic monomer PFEMA was changed: 0.8 g of DA-Gel, 0.5 g of SBMA, 1.0 g of AA, and 0.6 g of PFEMA were weighed and dissolved together in a 30% DMSO aqueous solution to prepare a prepolymer solution. The irradiation process used the same absorbed dose of 40 kGy as in Example 1. The resulting hydrogel was designated DSAF-3. Due to the increased PFEMA content, the hydrophobicity of the hydrogel was significantly enhanced, and the surface contact angle increased. However, its adhesion strength decreased to 81.50 ± 5.11 kPa, and the equilibrium swelling ratio increased to 18.33 ± 2.08%. Mechanical property tests indicated that its network uniformity might be altered due to the excessive hydrophobic component. This example demonstrates that there is an optimized PFEMA content range (such as 4% in Example 1), and excessive amounts may actually lead to a decrease in performance.

[0041] Example 4: First, DSAF hydrogel was prepared using the exact same method as in Example 1. Then, a 5% polyvinyl alcohol (PVA) aqueous solution was prepared. One side of the obtained DSAF hydrogel was immersed in the PVA solution for 5 seconds, then removed and frozen at -20 °C for 6 hours, followed by thawing at room temperature. This freeze-thaw cycle was repeated 3 times to form a stable, non-adhesive, porous PVA backing layer on one side of the DSAF hydrogel, resulting in a ready-to-use asymmetric hydrogel patch with strong adhesion on one side and anti-adhesion on the other. This patch can be used to prevent visceral adhesions after abdominal surgery and showed excellent anti-adhesion effects in a rat model of gastric perforation repair.

[0042] The attached chart provides a wealth of data, specifically: Figure 1 It's DA-Gel. 1 H nuclear magnetic resonance spectroscopy. (Through) 1 H-NMR spectroscopy confirmed the chemical structure of DA-Gel. 1 In the H-NMR spectrum, the magnified region between 6.5 and 7.0 ppm showed characteristic peaks corresponding to the aromatic protons on the dopamine benzene ring, which confirmed that dopamine was successfully bound to gelatin.

[0043] Figure 2These are the Fourier transform infrared (FT-IR) spectra of DSAF colloidal gels and their precursors. The FT-IR spectra of radiation-crosslinked DSAF hydrogels show characteristic absorption bands. For PAA, the peaks at 1733 cm⁻¹, 1270 cm⁻¹, and 1167 cm⁻¹ correspond to C=O vibrations, C–O symmetric vibrations, and asymmetric vibrations, respectively. For SBMA, the sharp peak at 1733 cm⁻¹ is attributed to C=O vibrations, while the peaks at 1622 cm⁻¹ and 1039 cm⁻¹ correspond to unsaturated C=C and S=O vibrations, respectively. For DA-Gel materials, the broad peaks in the 3600–3200 cm⁻¹ range are characteristic of hydroxyl (O–H) groups, while the significant broad peak near 1622 cm⁻¹ is associated with the amide I band, further confirming the successful dopamine modification of gelatin. For P(PFEMA) material, the observed peaks at 1733 cm⁻¹ and 1150 cm⁻¹ correspond to C=O vibration and C–F bond, respectively. The peak at 2985 cm⁻¹ corresponds to C–H vibration. Both the prepared DSA and DSAF hydrogels exhibit characteristic C=O peaks (approximately 1722 cm⁻¹) from PAA, SBMA, and P(PFEMA), as well as an S=O peak (1039 cm⁻¹) from SBMA. Simultaneously, the disappearance of the unsaturated C=C absorption peak at 1622 cm⁻¹ confirms the successful copolymerization of AA, SBMA, and PFEMA. The presence of broad O–H peaks (3600–3200 cm⁻¹) also indicates successful DA-Gel incorporation. Furthermore, the DSAF hydrogel containing the hydrophobic monomer PFEMA can be distinguished from the DSA hydrogel by the presence of a characteristic C–F peak at 1150 cm⁻¹, further confirming that PFEMA has been successfully incorporated into the hydrogel network.

[0044] Figure 3 This study tested the mechanical properties of DSAF hydrogels prepared under different irradiation doses. (a) Tensile shear test of DSAF hydrogels on pig skin under different irradiation doses (n=3). (b) Swelling behavior of DSAF hydrogels under different irradiation doses (n=3). (c) Elongation at break of DSAF hydrogels under different irradiation doses (n=3). Figure 3 (a) The adhesion properties were quantitatively evaluated by performing an overlap shear test after bonding the hydrogel to porcine skin. The results showed strong adhesion at the hydrogel-tissue interface, with the adhesion strength increasing with increasing irradiation dose. Specifically, the adhesion strength reached a maximum of 93.33 ± 2.95 kPa at a dose of 40 kGy. However, excessive irradiation leads to over-crosslinking, which increases the mechanical brittleness of the hydrogel and may consume key functional groups involved in adhesion. Therefore, selecting an appropriate irradiation dose is crucial for achieving strong adhesion at the hydrogel-tissue interface. Figure 3 (b) The results show that increasing the irradiation dose significantly reduces the expansion rate of the DSAF hydrogel, which is attributed to the enhanced crosslinking density induced by the higher radiation dose. Notably, the higher crosslinking density in the DSAF hydrogel is directly correlated with a more significant anti-expansion effect. Therefore, the ultra-low expansion properties of the DSAF hydrogel effectively help maintain its mechanical and adhesive strength, thereby minimizing the risk of wound rupture and exudate leakage. Figure 3 (c) The results show that the mechanical strength of the hydrogel generally increases with increasing radiation dose, reaching its optimal mechanical properties at 40 kGy. Compared with the hydrogel prepared at 15 kGy, its fracture strain increased from 161% to 736.33%, indicating a significant enhancement in chain entanglement and crosslinking density within the hydrogel network. However, above 45 kGy, the fracture strain and fracture stress begin to decrease, confirming the occurrence of over-crosslinking at higher doses, leading to a deterioration in mechanical properties.

[0045] Figure 4 The mechanical properties of DSAF hydrogels at different concentrations were tested. (a) Swelling characteristics of DSAF and DSA hydrogels (n=3). (b) Elongation at break of DSAF and DSA hydrogels (n=3). Figure 4 (a) The results show that the introduction of hydrophobic monomers significantly reduced the swelling rate of the hydrogel, which is attributed to the repulsive effect of the hydrophobic groups on water molecules and the dense cross-linked network formed by irradiation. However, at a fixed irradiation dose, excessively high hydrophobic monomer content may lead to incomplete cross-linking and uneven distribution of hydrophobic water areas within the network, thereby affecting the DSAF. 0.6 Its expansion rate is higher than that of other groups. Figure 4 (b) The results show that with the increase of hydrophobic monomer content, DSAF 0.2 The fracture strain decreased while the fracture stress increased, indicating that the hydrophobic groups significantly enhanced the rigidity of the hydrogel. However, compared with DSAF... 0.4 In comparison, DSAF 0.6 The fracture strain decreased, indicating that the excessive hydrophobic monomer content exacerbated the network inhomogeneity due to uneven crosslinking, thereby impairing mechanical properties.

[0046] Figure 5 This is an adhesiveness test of DSAF hydrogel. (a) Adhesion strength test between DSAF hydrogel and pig skin (n=3). (b, c) 180° peel adhesion strength test of DSAF hydrogel (n=3). (d) Bursting pressure test of pig skin sealed with DSAF hydrogel through a 5 mm diameter incision (n=3). Figure 5(a) The results showed that strong adhesion was observed at the tissue interface. Adhesion strength increased with increasing concentration of the hydrophobic monomer PFEMA, but decreased for DSAF. 0.6 However, it has declined. Figure 5 The results (b, c) further confirm the DSAF. 0.4 The hydrogel exhibits high interfacial toughness (400.8 ± 22.53 J m⁻²). Figure 5 (d) The results show that DSA-F 0.4 The maximum withstand burst pressure (341.07 ± 9.34 mmHg) was significantly higher than that of DSA (166.13 ± 7.34 mmHg) and DSA-F. 0.2 (283.90 ± 12.95 mmHg) and DSAF 0.6 (221 ± 15.31 mmHg). The pressure resistance initially increased with increasing hydrophobic monomer content, but for DSAF... 0.6 However, the adhesion decreased, which can also be attributed to incomplete cross-linking caused by excessive hydrophobic monomers. Therefore, the DSAF hydrogel can still maintain strong adhesion to the tissue after swelling on the surface of pig skin, and the hydrophobic C–F groups help to mitigate the adverse effects of surface liquids on its mechanical properties.

[0047] Figure 6 The image shows a photograph of the DSAF hydrogel (a) and its corresponding hemolysis rate (b) (n=3). Figure 6 Statistical analysis of the data (a, b) shows that the hemolysis rate of all DSAF hydrogel groups was less than 5%, indicating that their blood compatibility was within the biosafety range.

[0048] Figure 7 (a) MTT assay of L929 cells cultured in DSAF hydrogel extract (n=3). (b) Live / dead staining of L929 cells cultured in DSAF hydrogel extract (n=3). Figure 7 (a) The results showed that the cell survival rate in all groups exceeded 80%. Figure 7 (b) Staining results showed that most cells in all groups were green (live) with only a small number of red (dead) cells, indicating low cytotoxicity. In summary, the MTT data and live / dead cell staining results confirmed the low cytotoxicity of this hydrogel and validated the good cell compatibility of the DSAF hydrogel.

[0049] Figure 8(a) Bacterial survival rates of Escherichia coli and Staphylococcus aureus colonies on agar plates after different hydrogel treatments (n=3) and (b) Photographs and scanning electron microscope (SEM) images (n=3). The clearly visible observations in Figures (a, b) indicate that DSAF and DSA hydrogels exhibit significant bactericidal properties against both bacterial strains compared to FSA hydrogel. E. coli and S. aureu The bacterial survival rate in the DSAF and DSA hydrogel groups was extremely low, while the bacterial survival rate in the FSA group was higher but the bactericidal effect was lower. Furthermore, scanning electron microscopy imaging of the agar plates showed that the bacterial survival rate in the DSAF and DSA hydrogel groups was significantly lower. E. coli and S. aureus The cells all exhibited significant shrinkage and deformation, indicating a strong antibacterial effect. In contrast, the bacteria in the FSA colloidal gel group showed only slight shrinkage, suggesting weaker antibacterial activity.

[0050] Figure 9 Hematologic and immunological (H&E) staining was performed on visceral tissues, including the heart, liver, spleen, lungs, and kidneys, isolated from normal mice and surgically treated mice that underwent subcutaneous implantation of DSAF hydrogel. This experiment was conducted 28 days post-implantation. Results showed that on day 28 post-implantation, samples from major organs (including the heart, liver, spleen, lungs, and kidneys) were stained with H&E. No abnormalities were detected in these tissues, indicating that the DSAF hydrogel is biocompatible for in vivo application.

[0051] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, such as adjusting the degree of substitution of DA-Gel, changing the monomer ratio of SBMA and AA, selecting other radiation doses in the range of 20-50 kGy, or selecting other PFEMA contents in the range of 2%-6%, etc., without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a multifunctional bioadhesive hydrogel, characterized by, Includes the following steps: ①Preparation of dopamine-modified gelatin; ② Preparation of prepolymer solution: Dissolve the dopamine-modified gelatin, sulfobetaine methacrylate, acrylic acid, and perfluoroalkyl ethyl methacrylate obtained in step ① in a dimethyl sulfoxide aqueous solution and stir until a homogeneous and transparent solution is formed; wherein, the mass percentage of each component in the prepolymer solution is: dopamine-modified gelatin 5-10%, sulfobetaine methacrylate 4-6%, acrylic acid 8-12%, perfluoroalkyl ethyl methacrylate 2-6%, and the balance is a dimethyl sulfoxide aqueous solution, wherein the volume concentration of dimethyl sulfoxide is 25-35%; ③Radiation crosslinking: The prepolymer liquid obtained in step ② is injected into the mold and irradiated with an electron beam with a radiation absorption dose of 20-50 kGy to induce a copolymerization crosslinking reaction and form a hydrogel with a three-dimensional interpenetrating network structure. ④ Post-processing: Take out the hydrogel obtained in step ③, soak it in deionized water to replace the residual solvent, and obtain the multifunctional bioadhesive hydrogel.

2. The method for preparing the multifunctional bioadhesive hydrogel according to claim 1, characterized in that, In step ①, the preparation method of the dopamine-modified gelatin is as follows: gelatin is dissolved in phosphate buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are added, the pH is adjusted to 5.0-6.0, dopamine hydrochloride is added after activation, and the reaction is carried out at room temperature in the dark for 20-28 hours. After the reaction is completed, the gelatin is purified by dialysis and freeze-dried.

3. The method for preparing the multifunctional bioadhesive hydrogel according to claim 1, characterized in that, In step ②, the mass percentage of each component in the prepolymer liquid is as follows: dopamine-modified gelatin 8%, sulfobetaine methacrylate 5%, acrylic acid 10%, and perfluoroalkyl ethyl methacrylate 4%.

4. The method for preparing the multifunctional bioadhesive hydrogel according to claim 3, characterized in that, In step ②, the perfluoroalkyl ethyl methacrylate has a mass percentage of 4% in the prepolymer solution.

5. The method for preparing the multifunctional bioadhesive hydrogel according to claim 1, characterized in that, In step ③, the energy of the electron beam is 1 MeV.

6. The method for preparing the multifunctional bioadhesive hydrogel according to claim 5, characterized in that, In step ③, the absorbed radiation dose is 40 kGy.

7. The method for preparing the multifunctional bioadhesive hydrogel according to claim 1, characterized in that, Step ④ is followed by step ⑤: a layer of polyvinyl alcohol is laminated onto one surface of the hydrogel obtained in step ④ to form an asymmetric hydrogel patch with one side being adhesive and the other side being non-adhesive.

8. A multifunctional bioadhesive hydrogel prepared by the preparation method according to any one of claims 1 to 7, characterized in that, Its equilibrium swelling ratio in phosphate buffer is 8-15%.

9. The multifunctional bioadhesive hydrogel according to claim 8, characterized in that, Its adhesion strength to moist pigskin tissue is 80-100 kPa, its interfacial toughness is 350-450 J m⁻², and its burst pressure resistance is 300-360 mmHg.

10. An application of a multifunctional bioadhesive hydrogel, characterized in that, The application of the multifunctional bioadhesive hydrogel according to any one of claims 1-7 in medical devices, medical dressings, and bioadhesives for wound hemostasis, surgical incision closure, repair of perforations of internal organs, and healing of infected wounds.

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