Mechanical multifunctional hydrogel with eight-arm cage nanostructure for wounds

Abstract

The invention relates to a mechanical multifunctional hydrogel with an eight-arm cage nanostructure for wounds and a preparation method thereof. The hydrogel network has a mechanical regulation function and is formed by photopolymerization of methacrylated gelatin, octavinyl-polyhedral oligomeric silsesquioxane and N-isopropylacrylamide, the process is simple and convenient, and large-scale preparation is easy. The hydrogel has ideal adhesion, photo-thermal conversion, biocompatibility and wound healing promotion performance. The purple cabbage anthocyanin is used as a natural visual probe and can be used for monitoring the wound microenvironment in real time. The nanocage cross-linked network is used as a rigid frame, so that the excessive expansion of the biopolymer hydrogel matrix can be limited, and the functional damage and wound self-constriction blocking caused by liquid absorptive swelling of the dressing are avoided. When the resveratrol nano-vesicles cover a skin wound, the hydrogel can pull the wound to contract towards the center to promote wound healing, and the resveratrol nano-vesicles are continuously released, so that regeneration and vascularization of wound tissues are promoted, and excessive inflammatory response is relieved.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to a mechanically multifunctional hydrogel that combines multiple components and has an eight-armed cage nanostructure, and its preparation method. Background Technology

[0002] As the primary interface with the external environment, the skin is highly susceptible to damage from thermal injuries (such as burns), mechanical trauma (such as accidents), and chronic diseases (including diabetes and vascular diseases). Timely wound care after injury is crucial for accelerating the healing process and reducing the psychological burden on patients. Without timely care, these wounds are highly vulnerable to microbial invasion and infection, significantly delaying the healing process. Traditional clinical wound management primarily relies on wrapping or applying pressure to sutured wounds with gauze, cotton thread, and bandages. While these methods are cost-effective and easy to use, they heavily depend on clinical experience for frequent dressing changes and disinfection. Frequent checks and dressing changes can increase the risk of recurrent infections and cause secondary damage to newly formed skin tissue. In recent years, the understanding of wound management has undergone a significant shift: from a dry wound environment promoting healing to an appropriately moist environment that is more conducive to improving the quality and speed of wound healing. Therefore, there is an urgent need for a new, multifunctional material that can both monitor the wound in real time and actively promote wound healing, accelerating the overall healing process.

[0003] Methacrylamide gelatin is a semi-synthetic photocrosslinked gelatin polymer obtained by modifying the amine groups in gelatin with methacrylic anhydride. The presence of the methacryloyl group allows methacryloylamide gelatin to undergo free radical polymerization in the presence of a photoinitiator, thereby forming covalent bonds between polymer chains and ultimately forming a crosslinked hydrogel network. Despite the modification with methacrylic anhydride, its biocompatibility and biodegradability are not affected. Furthermore, methacryloylamide gelatin retains the arginine-glycine-aspartic peptide sequence and the target sequence of matrix metalloproteinases in gelatin, which can provide more cell attachment sites, thereby promoting tissue integration and regeneration. Simultaneously, as a partial hydrolysate of collagen, gelatin-based hydrogels can participate in collagen deposition during the healing process. Therefore, numerous methacryloylamide gelatin hydrogel dressing systems have been developed for the treatment of soft tissue injuries. Currently, many gelatin-based hydrogels are being developed to eliminate inflammatory factors or kill bacteria in wounds to restore the normal healing process. They also aim to promote the activity of fibroblasts, keratinocytes, and endothelial cells by delivering bioactive factors (such as growth factors, oxygen, and cells), thereby achieving collagen deposition, re-epithelialization, and angiogenesis. However, most of these gelatin-based hydrogels rely on biochemical methods to regulate the wound microenvironment. While they can effectively promote cell proliferation or inhibit infection, they struggle to directly address the critical physical challenge of wound closure. The difficulty in wound closure lies in overcoming tissue retraction, persistent tension, and maintaining precise closure. Improper closure can easily lead to delayed healing, scar hyperplasia, or even re-dehiscence. Therefore, while improving the microenvironment through biochemical methods, developing hydrogel materials that can actively provide mechanical force to physically reduce the wound area is crucial for achieving truly accelerated wound healing.

[0004] Embryonic wound healing enables the perfect regeneration of fetal skin, providing a new biomimetic approach for wound dressing design. The key to this process lies in the actin cords formed within the cells at the wound edge. The tension generated by their contraction actively pulls the wound edge closed in a "closing" manner. This is essentially a biomechanical strategy that promotes wound contraction by actively applying mechanical force. This mechanical signal can regulate the mechanical microenvironment of the wound, further promoting cell proliferation, collagen deposition, and angiogenesis. Simultaneously, receptors on the fibroblast membrane surface can recognize externally applied mechanical stress, prompting fibroblasts to activate and differentiate into myofibroblasts, thereby further accelerating wound closure. Inspired by this, the successful application of negative pressure wound therapy and recent research progress in mechanically driven muscle regeneration have jointly driven the exploration of designs for dressings that actively generate mechanical signals to promote healing. In such designs, the dressing should possess biomechanical activity to achieve active mechanical regulation of the wound, thus meeting the following key requirements: (i) possessing appropriate mechanical strength and toughness; (ii) being able to actively respond and generate centripetal contraction force after application; and (iii) achieving effective adhesion to the skin to ensure efficient transmission of contraction force to the wound edge. N-Isopropylacrylamide (NIPAM) monomers are hydrophilic, but their polymers transform into hydrophobic states when the temperature rises to approximately 32°C. Based on this property, hydrogels exhibiting both thermal responsiveness and active hydrophobicity can be prepared via polymerization in an aqueous phase. At room temperature, this hydrogel remains hydrophilic, facilitating long-term stable storage. When applied to wound surfaces, it transforms into a hydrophobic state triggered by body temperature, thus avoiding the problem of traditional hydrophilic dressings swelling and opening the wound. Simultaneously, it achieves both active hydrophobicity and self-contraction, promoting wound closure and healing. Polyhedral oligosiloxanes (POSS) are considered among the smallest nano-hybrid molecules. Their structure centers on a cubic silica core, with various organic groups (such as alkyl, alkenyl, and aryl groups) connected to the vertices, some of which are reactive or polymerizable. POSS-based hybrid organic-inorganic polymer systems exhibit significant improvements in mechanical and physical properties, including higher thermal decomposition temperatures, higher moduli, excellent oxidation resistance, and loading capacity, providing a new direction for the development of high-performance hybrid materials. Furthermore, the application potential of POSS-based nanocomposites in the field of biomaterials is attracting increasing attention. Compared to toxic organic crosslinking agents and carbon nanotubes, POSS components possess excellent biocompatibility and low toxicity; their unique molecular-level dispersion characteristics can effectively regulate polymer chain movement, endowing POSS hydrogels with comprehensive properties such as low swelling, high tensile strength, self-healing, and conductivity, making them promising candidates for next-generation biomedical materials. If the double bonds at the top of octavinyl-cage polysilsesquioxane (OV-POSS) can be copolymerized with NIPAM monomers to construct a tunable crosslinking network in the hydrogel system, thereby achieving precise control over the hydrogel's shrinkage behavior, it will have considerable application potential.

[0005] To address the issue that ordinary dressings may hinder wound observation and fail to reflect its dynamic progress, this invention introduces purple cabbage anthocyanins as a natural, visual pH probe into the hydrogel system for real-time monitoring of the affected area's microenvironment. Anthocyanins exhibit a distinct color response to changes in the pH of exudate, thus intuitively reflecting the dynamics of the microenvironment during wound healing. This provides immediate and visually crucial information for assessing infection risk and healing progress, while avoiding potential biosafety issues associated with using traditional synthetic dyes as probes. Furthermore, addressing the common problems of impaired angiogenesis and excessive inflammatory responses during wound healing, this invention loads resveratrol nanovesicles into the hydrogel system. Resveratrol can promote wound tissue regeneration and vascularization by upregulating the expression of vascular endothelial growth factor; it can also inhibit the expression of pro-inflammatory factors such as tumor necrosis factor-α, thereby alleviating excessive inflammatory responses. During treatment, near-infrared light-triggered photothermal therapy is further combined, inducing mild local thermal stimulation through a gentle and controllable thermal effect. This thermal stimulation synergistically works with resveratrol in promoting angiogenesis, thereby more effectively accelerating wound healing.

[0006] In summary, this invention designs a mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound treatment, integrating multiple functions such as active wound closure, biochemical regulation, and real-time monitoring. This hydrogel can drive the contraction of its modified gelatin monomers, responsive monomers, and eight-armed cage nano-crosslinking units through a thermo-responsive hydrophilic-hydrophobic transition, thereby generating a continuous and stable contractile force. This effectively pulls the skin tissue in the attachment area to contract centripetally, promoting the gradual closure of the wound. This active kinetic stimulation also helps regulate collagen deposition, angiogenesis, and extracellular matrix remodeling, further accelerating the healing process. Compared to current hydrogel dressings that mainly focus on anti-infection and anti-inflammatory biochemical regulation, this invention shifts the focus from simply regulating the microenvironment to actively applying mechanical intervention, achieving effective regulation of the treatment process through non-pharmacological and non-invasive physical methods. This active mechanical regulation strategy provides new ideas for the design of medical dressings and expands the application potential of hydrogels in wound management. Summary of the Invention

[0007] Technical solution: In order to achieve the above objectives, the present invention proposes a mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wounds and its preparation method.

[0008] The aforementioned mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application is characterized by the following specific preparation steps:

[0009] (1) Prepare 100mg of methacrylamide gelatin into a 10wt% aqueous solution, add 2.5mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone to the aqueous solution and heat to dissolve, then add 1~5mg of octavinyl-cage polysilsesquioxane, 50~300mg of N-isopropylacrylamide and 2~10mg of dopamine hydrochloride, and heat and stir until completely dissolved;

[0010] (2) Add 0.1-0.5 wt% of purple cabbage anthocyanin probe and 5-10 wt% of resveratrol nanovesicles to the mixture solution in (1), and stir to obtain a uniform and transparent pregel solution.

[0011] (3) At room temperature, the pregel solution was irradiated with 6W 365nm ultraviolet light for 4 to 8 minutes to obtain a mechanically multifunctional hydrogel with an eight-armed cage nanostructure through polymerization reaction.

[0012] The aforementioned mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application is characterized in that the methacrylamide gelatin in the mechanically multifunctional hydrogel component is prepared by mixing methacrylic anhydride and gelatin, with a molecular weight of 8~14kDa, and is used as the hydrogel matrix; 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is a photoinitiator; octavinyl-cage polysilsesquioxane is used to construct a tunable crosslinking network in the hydrogel system; N-isopropylacrylamide helps the hydrogel achieve a hydrophilic-hydrophobic transition under thermal induction; and dopamine endows the hydrogel with photothermal conversion ability and enhances its tensile mechanical properties.

[0013] The aforementioned mechanically multifunctional hydrogel for wounds, characterized by having an eight-armed cage nanostructure, is wherein the purple cabbage anthocyanin probe in the mechanically multifunctional hydrogel component is prepared by extracting dried purple cabbage powder with 70% ethanol and then freeze-drying it to achieve visual monitoring of the pH value of the wound microenvironment.

[0014] The above-mentioned mechanically multifunctional hydrogel for wounds with an eight-armed cage nanostructure is characterized in that the resveratrol nanovesicles in the mechanically multifunctional hydrogel component are prepared by ultrasonic emulsification of soybean lecithin and resveratrol, and are continuously released as an active ingredient.

[0015] The above-mentioned mechanical multifunctional hydrogel with an eight-armed cage nanostructure for use on wounds is characterized in that, when the mechanical multifunctional hydrogel is used, it is applied to the wound and gently pressed to achieve adhesion, and then irradiated with an 808nm near-infrared light source for 2 minutes, after which the light source is removed. Attached Figure Description

[0016] Figure 1These are scanning electron microscope images of the mechanically multifunctional hydrogel prepolymer solution described in this invention before and after polymerization, and of the cross-section of the hydrogel after polymerization.

[0017] Figure 2 The infrared spectrum of the mechanically multifunctional hydrogel described in this invention is shown (with methacrylamide gelatin hydrogel and blank hydrogel without anthocyanin probe and resveratrol nanovesicles as references).

[0018] Figure 3 This invention relates to the thermal response shrinkage properties of the mechanically multifunctional hydrogel and its dimensional properties before and after thermal shrinkage.

[0019] Figure 4 The results show the response of the purple cabbage anthocyanin probe loaded on the mechanically multifunctional hydrogel described in this invention to different pH environments.

[0020] Figure 5 The release results of resveratrol nanovesicles loaded on the mechanically multifunctional hydrogel described in this invention.

[0021] Figure 6 The therapeutic effect of the mechanically multifunctional hydrogel described in this invention on mouse wounds. Specific Implementation

[0022] The following is a detailed description of the present invention. While specific embodiments of the invention have been shown, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0023] Example 1

[0024] 4.0 g of vacuum-dried purple cabbage powder was soaked in 20 mL of 70% ethanol solution (adjusted to pH=2) and magnetically stirred at 500 r / min for 60 min. Then, it was centrifuged at 4500 r / min for 20 min and the supernatant was collected. The supernatant was concentrated and dried by rotary evaporator at 50℃ in the dark, and then freeze-dried for 24 h to obtain purple cabbage anthocyanin extract.

[0025] Example 2

[0026] 70 mg of soybean lecithin and 2 mg of resveratrol were dissolved in 5 mL of chloroform. Then, 0.5 mL of pure water was added dropwise, and the mixture was sonicated at 30 °C and 40 kHz for 10 min. The resulting emulsion was magnetically stirred at 50 °C for 2 h. After the reaction was completed, the chloroform was removed by rotary evaporation at room temperature. Then, 5 mL of pure water was added, and the mixture was sonicated at 40 kHz for 15 min. The emulsion was then filtered through a 0.22 μm filter membrane to obtain resveratrol nanovesicles.

[0027] Example 3

[0028] 1 g of gelatin was added to 10 mL of phosphate buffer solution (1×, pH 7.4) and magnetically stirred in a 40 °C water bath for 1 h. Then, 0.6 mL of methacrylic anhydride solution was added dropwise to the gelatin solution at a rate of 0.5 mL / min, and magnetically stirred in a 50 °C water bath under dark conditions. After 3 h, 40 mL of preheated PBS solution was added to the flask to terminate the reaction. The resulting solution was dialyzed for one week in a 40 °C water bath under dark conditions (dialysis bag molecular weight cutoff 8–14 kDa). After dialysis, the sample was placed in a -80 °C ultra-low temperature freezer overnight, and then freeze-dried for 48 h to obtain methacrylamide gelatin.

[0029] Example 4

[0030] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. The resulting prepolymer was injected into a mold and photocrosslinked by irradiation with 6W 365nm UV light for 4 min to form a methacrylamide gel hydrogel.

[0031] Example 5

[0032] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 100 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. The resulting prepolymer was injected into a mold and photocrosslinked by irradiation with 6W 365nm UV light for 8 min to form a blank hydrogel.

[0033] Example 6

[0034] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage polysilsesquioxane and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and irradiated with 6W 365nm UV light for 8 min to perform photocrosslinking, forming a multifunctional hydrogel.

[0035] Example 7

[0036] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 50 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and irradiated with 6W 365nm UV light for 8 min to perform photocrosslinking, forming a mechanically multifunctional hydrogel.

[0037] Example 8

[0038] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 100 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and photocrosslinked by irradiation with 6W 365nm UV light for 8 min to form a mechanically multifunctional hydrogel.

[0039] Example 9

[0040] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10 wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 150 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and photocrosslinked by irradiation with 6W 365nm UV light for 8 min to form a mechanically multifunctional hydrogel.

[0041] Example 10

[0042] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 200 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and photocrosslinked by irradiation with 6W 365nm UV light for 8 min to form a mechanically multifunctional hydrogel.

[0043] Example 11

[0044] Methacrylamide gelatin was completely dissolved in pure water in a 45°C water bath to prepare a 10wt% methacrylamide gelatin solution. 2.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone was weighed and added to the methacrylamide gelatin solution, and the mixture was heated and stirred until completely dissolved. Then, 2 mg of octavinyl-cage-like polysilsesquioxane, 300 mg of N-isopropylacrylamide, and 8 mg of dopamine hydrochloride were added sequentially, and the mixture was stirred for 30 min until homogeneous. Next, 2 mg of anthocyanin and 100 μL of resveratrol nanovesicles were added to the solution, and the mixture was stirred at 25°C and 600 rpm for 10 min until homogeneous. The resulting prepolymer was injected into a mold and irradiated with 6W 365nm UV light for 8 min to perform photocrosslinking, forming a mechanically multifunctional hydrogel.

[0045] Figure 1This study demonstrates the transformation of a prepolymerized mechanically multifunctional hydrogel from a fluid liquid state to a fixed hydrogel state under ultraviolet irradiation. Furthermore, scanning electron microscopy observations of the cross-section of the hydrogel reveal a uniform and interconnected porous structure. This porous structure is crucial for applications such as tissue engineering and drug delivery, which require materials capable of controlled loading and release of bioactive agents. The porous structure not only enhances the mechanical properties of the hydrogel but also provides a favorable environment for cell infiltration and nutrient transport.

[0046] Figure 2 The infrared spectra of the hydrogels prepared in Examples 4, 5, and 8 are shown. In the infrared spectrum of the methacrylamide gelatin hydrogel prepared in Example 4, the [insert value here] is located at 1540 and 1640 cm⁻¹. -1 The absorption peaks are assigned to the amide II band (N–H stretching vibration) and the amide I band (C=O stretching vibration), respectively; located at 1452 cm⁻¹. -1 The absorption peak at [value] corresponds to the CH bending vibration of the methyl group. These characteristic peaks collectively confirm that the methacryloyl group has been successfully grafted onto the gelatin. In the infrared spectrum of the blank hydrogel without anthocyanin probe and resveratrol nanovesicles prepared in Example 5, [value] is located at 2970 cm⁻¹. -1 The characteristic peaks at [values ​​missing] are attributed to the C–H stretching vibrations of the methyl and methylene groups. Compared to methacrylamide gelatin hydrogel, the peak intensity is significantly enhanced, indicating that N-isopropylacrylamide has been successfully introduced into the system. [Values ​​missing] are located at 971, 838, and 594 cm⁻¹. -1 The absorption peaks at these locations are attributed to the aromatic substitution structure. In the infrared spectrum of the mechanically multifunctional hydrogel prepared in Example 8, the peaks are located at 584, 778, and 1112 cm⁻¹. -1 The absorption peaks at 1053 and 1228 cm⁻¹ are attributed to the stretching and bending vibrations of the Si-O-Si bonds, indicating that octavinyl-cage-like polysilsesquioxane is successfully incorporated into the hydrogel structure. Furthermore, the absorption peaks at 1053 and 1228 cm⁻¹ are also significant. -1 The characteristic peaks at these locations are attributed to the stretching vibrations of POC and P=O, respectively, confirming that resveratrol nanovesicles were successfully encapsulated in the mechanically multifunctional hydrogel. Notably, with the incorporation of anthocyanin probes and resveratrol nanovesicles, the absorption peak of the OH stretching vibration in the mechanically multifunctional hydrogel exhibits a red shift, indicating the presence of intermolecular hydrogen bonds between the anthocyanin probes and resveratrol nanovesicles and the hydrogel components.

[0047] The mechanically multifunctional hydrogel prepared in Example 8 was subjected to swelling experiments, adhesion tests, in vitro cytotoxicity evaluation, heat-induced contraction behavior tests, color response tests at different pH levels, drug release tests, and in vivo mouse experiments. The results are as follows:

[0048] Observations revealed that the mechanically multifunctional hydrogel prepared in Example 8 absorbed water and swelled at 25°C, reaching equilibrium after 12 hours. However, at 37°C, the hydrogel not only failed to swell but also expelled water, resulting in a weight reduction, and reached equilibrium after 10 hours. These results indicate that at 37°C, the mechanically multifunctional hydrogel can still shrink in the presence of external liquid, achieving both wound closure and avoiding the risk of the hydrogel absorbing water and swelling within the wound, thus opening it up.

[0049] To evaluate the adhesion properties of the mechanically multifunctional hydrogel prepared in Example 8 to biological tissues, the overlap shear test was performed according to the national standard GB / T 39295-2020, with the substrate replaced by fresh pigskin, which is more suitable for the application scenario. The adhesion strength of the mechanically multifunctional hydrogel on the pigskin tissue interface was determined by the overlap shear test. The results showed that the mechanically multifunctional hydrogel exhibited relatively excellent adhesion properties on the pigskin tissue interface, with a maximum adhesion strength of 7.23 ± 0.50 kPa. This value is comparable to that of commercially available fibrin glue bioadhesives commonly used in clinical practice, showing good application potential. Furthermore, when the mechanically multifunctional hydrogel was applied to the skin of a finger, it remained firmly adhered to the skin surface even under deformation at different angles. The hydrogel also showed certain adhesion capabilities to various non-biological materials, such as rubber, plastics, glass, aluminum foil, and stainless steel. These experimental results demonstrate that the prepared mechanically multifunctional hydrogel possesses excellent adhesion properties, laying a necessary foundation for subsequent adhesion to skin tissue and traction of its contraction.

[0050] Following the test methods specified in the national standard GB / T 16886.5-2017 "Biological Evaluation of Medical Devices Part 5: In Vitro Cytotoxicity Tests", the in vitro cytotoxicity of the mechanically multifunctional hydrogel prepared in Example 8 was evaluated using L929 mouse fibroblasts. After culturing cells with the mechanically multifunctional hydrogel extract for 24 h and 48 h, the viability of L929 cells was higher than 90%, and the cells exhibited a high survival rate. This indicates that the mechanically multifunctional hydrogel has excellent biocompatibility and is beneficial for cell proliferation. Furthermore, after co-culturing the mechanically multifunctional hydrogel extract with erythrocytes at 37°C for 3 h, the supernatant from the mechanically multifunctional hydrogel group after centrifugation had similar transparency to the negative control (cell culture-grade phosphate buffer, pH=7.2~7.4), indicating a low degree of erythrocyte rupture induced by the mechanically multifunctional hydrogel. In contrast, erythrocytes ruptured in all cases when deionized water was used as the positive control. The hemolysis rate of the mechanically multifunctional hydrogel extract-treated group was only 0.63%, meeting the safety requirements for medical hemostatic materials. These results demonstrate that the mechanically multifunctional hydrogel does not disrupt the morphological structure of erythrocytes and exhibits excellent blood compatibility and extremely low biotoxicity.

[0051] The mechanically multifunctional hydrogel prepared in Example 8 exhibited significant thermal shrinkage behavior after being placed in an environment of 37°C for 4 hours, and the content of N-isopropylacrylamide had a significant impact on its thermal shrinkage. Hydrogels prepared in Examples 6, 7, 9, 10, and 11 were used as references. Figure 3 The thermal shrinkage properties of the hydrogels were compared, and the dimensional appearance of the mechanically multifunctional hydrogel prepared in Example 8 before and after thermal shrinkage were shown. Under conditions where other components remained constant, the thermal shrinkage rate of the mechanically multifunctional hydrogel initially increased and then decreased with increasing content of the thermosensitive monomer N-isopropylacrylamide, reaching a maximum of 39.61% at an N-isopropylacrylamide content of 100 mg. The subsequent decrease in thermal shrinkage rate is likely due to the high concentration of N-isopropylacrylamide enhancing the rigidity of the hydrogel network, thereby inhibiting heat-induced shrinkage behavior.

[0052] Figure 4 The mechanically multifunctional hydrogel prepared in Example 8 exhibits a significant color response to different pH environments: at pH values ​​of 6, 8, and 10, the hydrogel displays pink, blue, and green, respectively, with corresponding RGB values ​​of (219, 196, 208), (52, 99, 150), and (101, 125, 6). These results demonstrate that anthocyanins derived from purple cabbage can serve as a natural visual probe, exhibiting a significant color response to changes in body fluid pH. This allows for a direct reflection of the acid-base dynamics during wound healing, enabling real-time monitoring of the wound microenvironment while avoiding the potential biosafety risks associated with traditional synthetic dyes.

[0053] Figure 5 The experiment demonstrates the release results of resveratrol vesicles from the mechanically multifunctional hydrogel prepared in Example 8. Specifically, the release rate determination method in the 2025 edition of the Chinese Pharmacopoeia was used. 1 g of hydrogel was immersed in 20 mL of phosphate buffer (pH 7.4). The system was placed in a constant-temperature shaker at 37°C, and the culture medium was removed and replaced with the same fresh medium at set time intervals. The drug release was calculated using UV-Vis spectrophotometry. In vitro release results indicate that the mechanically multifunctional hydrogel exhibits rapid release within the first 12 hours. Resveratrol enters the hydrogel through the rupture of liposomes and is released driven by concentration differences through the expansion and porous structure of the hydrogel network. When the release time reaches 24 hours, the cumulative release rate of resveratrol from the mechanically multifunctional hydrogel reaches 68.65%, indicating that the mechanically multifunctional hydrogel can serve as an effective carrier for resveratrol. Thanks to the dual encapsulation effect of nanovesicles and the hydrogel matrix, this system achieves efficient loading and long-term sustained release of resveratrol.

[0054] Balb / c mice, aged 6-8 weeks, were fed for one week, and their backs were shaved. Then, circular, full-thickness skin defects of approximately 6 mm in diameter were created using a punch. Two groups were treated with different materials: the control group received commercially available Tegaderm™ dressings, while the experimental group received the mechanically multifunctional hydrogel prepared in Example 8, combined with 808 nm near-infrared light irradiation. Figure 6 The results showed that the healing speed of the mechanically multifunctional hydrogel group was significantly faster than that of the control group, with only 5.11% of the wound remaining area by day 10. These results indicate that the active contraction behavior of the mechanically multifunctional hydrogel under thermal stimulation can effectively promote wound healing. Further combination with near-infrared phototherapy, the gentle and controllable thermal effect can induce mild local thermal stimulation. This thermal stimulation works synergistically with resveratrol in promoting angiogenesis, thereby more effectively accelerating wound healing.

Claims

1. A mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound treatment, characterized in that, The specific preparation steps of this mechanically multifunctional hydrogel are as follows: (1) Prepare 100mg of methacrylamide gelatin into a 10wt% aqueous solution, add 2.5mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone to the aqueous solution and heat to dissolve, then add 1~5mg of octavinyl-cage polysilsesquioxane, 50~300mg of N-isopropylacrylamide and 2~10mg of dopamine hydrochloride, and heat and stir until completely dissolved; (2) Add 0.1-0.5 wt% of purple cabbage anthocyanin probe and 5-10 wt% of resveratrol nanovesicles to the mixture solution in (1), and stir to obtain a uniform and transparent pregel solution. (3) At room temperature, the pregel solution was irradiated with 6W 365nm ultraviolet light for 4~8min, and a mechanical multifunctional hydrogel with an eight-armed cage nanostructure was obtained through polymerization reaction.

2. The mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application as described in claim 1, characterized in that, The methacrylated gelatin in the mechanically multifunctional hydrogel component is prepared by mixing methacrylic anhydride and gelatin, with a molecular weight of 8~14kDa, and is used as the hydrogel matrix; 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is a photoinitiator; octavinyl-cage polysilsesquioxane is used to construct a tunable crosslinking network in the hydrogel system; N-isopropylacrylamide helps the hydrogel achieve a hydrophilic-hydrophobic transition under thermal induction; and dopamine endows the hydrogel with photothermal conversion ability and enhances its tensile mechanical properties.

3. The mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application as described in claim 1, characterized in that, The purple cabbage anthocyanin probe in the mechanically multifunctional hydrogel component is prepared by extracting dried purple cabbage powder with 70% ethanol and then freeze-drying it to achieve visual monitoring of the pH value of the wound microenvironment.

4. The mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application as described in claim 1, characterized in that, The resveratrol nanovesicles in the mechanically multifunctional hydrogel component are prepared by ultrasonic emulsification of soybean lecithin and resveratrol, and can be continuously released as an active ingredient.

5. The mechanically multifunctional hydrogel with an eight-armed cage nanostructure for wound application as described in claim 1, characterized in that, When using the mechanically multifunctional hydrogel, apply it to the wound and gently press to achieve adhesion. Then irradiate it with an 808nm near-infrared light source for 2 minutes, and remove the light source afterward.

Images