Preparation method and application of Janus structure photo-thermal-piezoelectric hydrogel dressing for infected wound repair

Abstract

The invention relates to a preparation method and application of a Janus structure photo-thermal-piezoelectric hydrogel dressing for infected wound repair, and the preparation method comprises the following steps: respectively dissolving phenylboronic acid grafted methacrylamide gelatin and dopamine grafted hyaluronic acid in deionized water, adding MXene coated CeO2 heterojunction, and ultrasonically dispersing uniformly, so as to obtain the Janus structure photo-thermal-piezoelectric hydrogel dressing for infected wound repair. After mixing, sodium hydroxide is used for adjusting the pH value to alkalescence, and a Janus structure inner layer is formed; respectively dissolving phenylboronic acid grafted gelatin and o-nitrobenzyl alcohol grafted hyaluronic acid in deionized water, adding BaTiO3, ultrasonically dispersing uniformly, and mixing to form a Janus structure outer layer; the Janus structure photo-thermal-piezoelectric hydrogel dressing prepared by the invention has the characteristic of space-time release so as to adapt to the wound repair process, in addition, the Janus structure photo-thermal-piezoelectric hydrogel dressing also has excellent photo-thermal conversion performance, bacteria infecting the wound are killed through photo-thermal heating, physiological electric signals are effectively simulated through the piezoelectric effect, cell behaviors are regulated and controlled, and the Janus structure photo-thermal-piezoelectric hydrogel dressing can be used for wound infection repair.

Description

Technical Field

[0001] The present invention relates to the field of biomedical materials, and in particular to a preparation method and application of a Janus structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds. Background Art

[0002] With the continuous improvement of medical standards, infected wounds caused by trauma, diabetes, and post-surgery have become a thorny problem in clinical treatment. Infected wounds not only destroy the integrity of skin tissue, but also hinder the healing process due to bacterial growth and persistent inflammatory reactions. According to statistics, patients with severe infected wounds face the risk of serious complications such as tissue necrosis and sepsis, and even life-threatening conditions; while patients with chronic infected wounds suffer from long-term pain, long treatment cycles, and high medical costs, which bring a heavy burden to patients' families and the social medical system. Therefore, the development of new infected wound repair materials and technologies that are efficient, safe, and can accelerate healing has become a key need that needs to be urgently addressed in clinical treatment.

[0003] Traditional wound repair dressings only provide simple isolation and protection, and their porous structure cannot effectively block bacterial invasion. Furthermore, these dressings have poor water retention and air permeability, which can easily lead to dryness, scabs, or fluid accumulation on the wound surface. This not only hinders the growth of new tissue but also delays the healing process. Frequent replacement can easily cause secondary damage. In recent years, new wound dressings have continued to emerge, among which hydrogel dressings stand out due to their unique advantages. They have high water content and good biocompatibility, providing moist healing conditions for the wound surface and promoting epithelial cell migration and proliferation. In addition, their porous structure can also load active substances such as drugs and growth factors, enabling localized drug delivery to the wound surface, making them a research hotspot in the field of wound repair. However, existing single-function hydrogel dressings still have obvious shortcomings. Although antibacterial hydrogels can inhibit bacterial growth, their promotion of wound healing is limited. Although pro-repair hydrogels can accelerate tissue regeneration, they are difficult to effectively control infection. In the process of infected wound repair, infection control and tissue repair are two interrelated and complementary links. Single-function hydrogel dressings cannot achieve multi-dimensional coordinated treatment of infected wounds, and it is difficult to meet the dual needs of infection control and tissue repair at the same time. It is urgent to develop new hydrogel dressings with multiple functions.

[0004] The photothermal effect utilizes the heat generated by photothermal materials under illumination to destroy bacterial cell membrane structure and protein activity through high temperatures, achieving highly effective sterilization. It also offers advantages such as being contactless, remotely controllable, and less susceptible to developing drug resistance. Piezoelectric-assisted repair technology, on the other hand, leverages the weak electric field generated by piezoelectric materials when subjected to force to mimic human physiological electrical signals. This effectively regulates cell behavior, promoting cell adhesion, proliferation, and differentiation, and accelerating wound tissue regeneration. Both technologies have shown significant potential for application in wound repair, offering new approaches for treating infected wounds. However, the current application of photothermal and piezoelectric technologies in wound repair dressings presents numerous challenges. While photothermal antibacterial technology alone can rapidly kill bacteria, it cannot actively promote tissue repair, and prolonged high temperatures may cause thermal damage to surrounding healthy tissue. While piezoelectric-assisted repair technology alone can effectively regulate cell function, it lacks effective infection control, making it difficult to create favorable conditions for wound healing in an infected environment. Furthermore, integrating both photothermal and piezoelectric technologies into a single dressing presents technical challenges, such as poor material compatibility, interference between functional modules, and difficulty in precisely controlling the synergistic function of the two. Therefore, it is urgent to design an innovative structure so that the two functions of photothermal antibacterial and piezoelectric repair can play their roles in an orderly manner, so as to first use the photothermal effect to quickly kill the bacteria on the wound surface and control the infection, and then the piezoelectric effect can continue to work to promote tissue repair, thereby meeting the dual requirements of infection control and tissue repair in the repair of infected wounds.

[0005] Thanks to its unique dual-sided, differentiated properties, Janus hydrogels can incorporate two or more distinct functional components onto either side of the structure, achieving the dual benefits of rapid antibacterial activity and sustained repair. Compared to traditional single-structure hydrogels, Janus hydrogels achieve spatial separation and synergy between photothermal and piezoelectric materials through precise interface control and microstructural design, preventing mutual interference between the two functional components and improving overall performance. One side anchors the photothermal material, rapidly generating high temperatures to kill bacteria under illumination, while the other side incorporates the piezoelectric material, which generates microcurrents through mechanical stimulation, modulating cellular behavior and promoting tissue repair. Furthermore, the unique spatial distribution of the Janus structure enables the sequential release of active ingredients. Based on the needs of different wound repair stages, the Janus hydrogel is designed to rapidly release the photothermal antibacterial component to control infection in the early stages of repair. Once the infection resolves, the piezoelectric material continues to function, promoting tissue regeneration, achieving a dynamic, step-by-step approach to treating infected wounds. Applying the Janus structure to wound repair dressings not only breaks through the limitations of the single function of traditional dressings, but also innovatively achieves functional synergy through structural design, providing technical support for the development of new dressings with both efficient antibacterial and repair-promoting capabilities, and is expected to bring new solutions to the repair of infected wounds. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the first object of the present invention is to provide a Janus structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds, one layer of which has ROS response characteristics and is used to load MXene@CeO2 heterojunction, and the other layer has good adhesion properties and is used to load BaTiO3 with piezoelectric effect.

[0007] The second object of the present invention is to provide a method for preparing the Janus structure hydrogel.

[0008] A third objective of the present invention is to provide applications of the aforementioned Janus hydrogel. This Janus hydrogel exhibits a photothermal effect, inhibiting bacterial growth in infected wounds and disrupting bacterial biofilms. Furthermore, it exhibits excellent immunomodulatory effects. Furthermore, the Janus hydrogel exhibits excellent adhesion and piezoelectric effects, regulating cell behavior and promoting angiogenesis, making it suitable for repairing infected wounds.

[0009] To achieve the above object, the present invention provides the following technical solutions: In a first aspect of the present invention, a method for preparing a Janus structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds is provided, comprising the following steps: (1) Phenylboronic acid-grafted methacrylamide gelatin and dopamine-grafted hyaluronic acid were dissolved in deionized water, and MXene@CeO2 heterojunction was added and ultrasonically dispersed uniformly. After mixing, the pH was adjusted to slightly alkaline using sodium hydroxide to form the inner layer of the Janus structure. (2) Phenylboronic acid grafted gelatin and o-nitrobenzyl alcohol grafted hyaluronic acid were dissolved in deionized water respectively, and BaTiO3 was added and ultrasonically dispersed evenly. After mixing, a Janus structure outer layer was formed.

[0010] Preferably, the MXene@CeO2 heterojunction is prepared by the following steps: S1. Ti3AlC2MXene and LiF were dissolved in HCl and etched, washed to neutrality, and then exfoliated by ultrasonication. Single-layer Ti3C2MXene nanosheets were then collected by centrifugation. S2. CeO2 and the monolayer Ti3C2MXene nanosheet are ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0011] Preferably, in step S1, the Ti3AlC2MXene:LiF:HCl = 1-2 mmol:10-20 mmol:3-10 mL, the HCl concentration is 5-11 mol / L, the etching time is 24-36 hours, the ultrasonic stripping power is 200-400 W, the ultrasonic stripping time is 30-60 min, and the collection centrifugal speed is 3000-5000 rpm.

[0012] Preferably, in step S2, the mass ratio of the CeO2 to the single-layer Ti3C2MXene nanosheet is 1:1-1:5, and the ultrasonic dispersion time is 0.5-2 hours.

[0013] Preferably, in step S1, the concentration of the phenylboronic acid grafted methacrylamide gelatin is 10%-30%, the concentration of the dopamine grafted hyaluronic acid is 5%-15%, the concentration of the MXene@CeO2 heterojunction is 0.1-2.0 mg / mL, the concentration of sodium hydroxide is 0.5-2.0 M, and the pH range is 7-9.

[0014] Preferably, in step S2, the concentration of phenylboronic acid grafted gelatin is 10%-30%, the concentration of o-nitrobenzyl alcohol grafted hyaluronic acid is 1%-3%, and the concentration of BaTiO3 is 0.1-2.0 mg / mL.

[0015] The second aspect of the present invention provides a hydrogel dressing prepared by the method.

[0016] The third aspect of the present invention provides the use of the hydrogel dressing in preparing wound repair products.

[0017] Preferably, the wound surface includes any one or more of an infected wound surface, a diabetic wound surface, a burn wound surface and a complex wound surface.

[0018] The fourth aspect of the present invention provides the use of the hydrogel dressing in preparing a product having the following effects: antibacterial; active oxygen scavenging; anti-inflammatory; and immunomodulatory.

[0019] Compared with the prior art, the present invention has the following beneficial and unique effects: The Janus-structured photothermal-piezoelectric hydrogel of the present invention forms a Janus structure by hydrogen-bonding the inner and outer layers. This structure allows for the spatiotemporal release of active ingredients. The inner Janus layer directly contacts the wound surface and rapidly decomposes to release the MXene@CeO2 heterojunction, achieving rapid antibacterial properties. The outer Janus layer exhibits adhesion and piezoelectric effects, continuously regulating cell behavior, promoting angiogenesis, and thereby accelerating tissue repair, thus possessing both antibacterial and pro-repair functions. The prepared MXene@CeO2 heterojunction has a flaky structure and excellent photothermal antibacterial properties. It also exhibits advantages such as good photothermal stability, blood compatibility, low cytotoxicity, and immunomodulation. BaTiO3 exhibits a significant piezoelectric effect, promoting cell proliferation and differentiation, and regulating the behavior of vascular endothelial cells, making it suitable for wound infection repair products. Furthermore, the method of the present invention has the advantages of readily available raw materials, simple operation, and excellent results. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Figure 1 shows the photothermal effect of a MXene@CeO2 heterojunction. (A) Photothermal heating curves of MXene@CeO2 heterojunctions at different concentrations; (B) Photothermal heating curves of MXene@CeO2 heterojunctions at different powers; (C) Photothermal cycling curves of a MXene@CeO2 heterojunction; (D) Heating and cooling curves of a MXene@CeO2 heterojunction.

[0021] Figure 2 The antibacterial effect of Janus-structured hydrogels. (A) Bacterial growth; (B) SEM image; (C) Biofilm removal test results.

[0022] Figure 3 Figure 1: The repair effects of Janus-structured hydrogels and physically blended hydrogels on infected wounds. (A) General view of infected wound repair; (B) H&E staining of wound tissue; (C) Masson staining of wound tissue; (D) CD31 immunofluorescence staining of wound tissue. DETAILED DESCRIPTION

[0023] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0024] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0025] Example 1 A Janus structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds, the preparation steps of which are as follows: 1. Preparation of MXene@CeO2 heterojunction (1) 1.5 mmol Ti3AlC2MXene (commercial product, purchased from Forsman Technology (Beijing) Co., Ltd.) and 15 mmol LiF (lithium fluoride, Shanghai Myrel Biochemical Technology Co., Ltd.) were dissolved in 5 mL of 9 M HCl (hydrochloric acid) and reacted at room temperature for 24 hours for etching.

[0026] (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min.

[0027] (3) The mixed solution after stripping was centrifuged at 3500 rpm and remixed after centrifugation. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected.

[0028] (4) 5 mg of CeO2 (cerium dioxide) and 5 mg of single-layer Ti3C2MXene nanosheets were ultrasonically dispersed in pure water for 0.5 h to obtain a MXene@CeO2 heterojunction.

[0029] 2. Preparation of Janus structure hydrogel (1) 200 mg of GelMA-PBA (phenylboronic acid grafted methacrylamide gelatin, Guangzhou Chuangsai Biomedical Materials Co., Ltd.) and 1 mg of LAP (photocrosslinker phenyl (2,4,6-trimethylbenzoyl) lithium phosphate, Shanghai Yinchang New Materials Co., Ltd.) were dissolved in 1 mL of deionized water, and 1 mg of MXene@CeO2 heterojunction was added and ultrasonically dispersed evenly. Microspheres loaded with MXene@CeO2 heterojunction were prepared by microfluidic technology; 100 mg of HA-DA (dopamine grafted hyaluronic acid, Guangzhou Chuangsai Biomedical Materials Co., Ltd.) was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0030] (2) 100 mg of MXene@CeO2 heterojunction-loaded microspheres were mixed with 100 μL of HA-DA solution, and the pH of the system was adjusted to 7-9 using 1 M sodium hydroxide. The gelled microgel was injected into the mold to form the Janus inner layer.

[0031] (3) Dissolve 200 mg of Gel-PBA (phenylboronic acid grafted gelatin, Guangzhou Chuangsai Biomedical Materials Co., Ltd.) in 1 mL of deionized water, add 1 mg of BaTiO3 (barium titanate) and disperse it evenly by ultrasonication to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB (o-nitrobenzyl alcohol grafted hyaluronic acid, Shanghai Lingjiu Medical Technology Co., Ltd.) in 1 mL of deionized water to obtain a HA-NB solution.

[0032] (4) The Gel-PBA solution and the HA-NB solution were mixed in a volume ratio of 1:1 to form a gel. The gelled hydrogel was injected into the mold to form a Janus outer layer. The Janus inner layer and the Janus outer layer were combined by hydrogen bonds to form a Janus structure.

[0033] Example 2 A physical hybrid photothermal-piezoelectric hydrogel dressing for repairing infected wounds, the preparation steps of which are as follows: 1. Preparation of MXene@CeO2 heterojunction (1) Dissolve 1.5 mmol Ti3AlC2MXene and 15 mmol LiF (lithium fluoride) in 5 mL of 9 M HCl (hydrochloric acid) and react at room temperature for 24 hours for etching.

[0034] (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min.

[0035] (3) The mixed solution after stripping was centrifuged at 3500 rpm and remixed after centrifugation. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected.

[0036] (4) 5 mg of CeO2 (cerium dioxide) and 5 mg of single-layer Ti3C2MXene nanosheets prepared in step (3) were ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0037] 2. Preparation of hydrogel (1) 200 mg of GelMA-PBA and 1 mg of LAP were dissolved in 1 mL of deionized water, and 1 mg of MXene@CeO2 heterojunction was added and ultrasonically dispersed uniformly. Microspheres loaded with MXene@CeO2 heterojunction (GelMA-PBA microspheres) were prepared by microfluidic technology; 100 mg of HA-DA was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0038] (2) Dissolve 200 mg of Gel-PBA in 1 mL of deionized water, add 1 mg of BaTiO3 and disperse it evenly by ultrasonication to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB in ​​1 mL of deionized water to obtain a HA-NB solution.

[0039] (3) 100 mg of MXene@CeO2 heterojunction-loaded microspheres, 100 μL of HA-DA solution, 100 μL of Gel-PBA solution, and 100 μL of HA-NB solution were mixed evenly. The pH of the system was adjusted to between 7 and 8 using 1 M sodium hydroxide, and the gelled hydrogel was injected into the mold to form a composite hydrogel.

[0040] Comparative Example 1 Prepare the MXene@CeO2 heterojunction solution as follows: (1) Dissolve 1.5 mmol Ti3AlC2MXene and 15 mmol LiF in 5 mL 9 M HCl and allow to etch at room temperature for 24 hours. (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min; (3) The mixed solution after stripping was centrifuged at 3500 rpm, and then remixed. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected. (4) 5 mg of CeO2 and 5 mg of single-layer Ti3C2MXene nanosheets prepared in step (3) were ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0041] (5) Ultrasonic dispersion of 1 mg of MXene@CeO2 heterojunction in 1 mL of deionized water was performed to obtain a MXene@CeO2 heterojunction solution.

[0042] Comparative Example 2 Prepare the MXene@CeO2 heterojunction solution as follows: (1) Dissolve 1.0 mmol Ti3AlC2MXene and 10 mmol LiF in 5 mL 9M HCl and react at room temperature for 24 hours for etching; (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min; (3) The mixed solution after stripping was centrifuged at 3500 rpm, and then remixed. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected. (4) 5 mg of CeO2 and 5 mg of single-layer Ti3C2MXene nanosheets prepared in step (3) were ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0043] (5) Ultrasonic dispersion of 1 mg of MXene@CeO2 heterojunction in 1 mL of deionized water was performed to obtain a MXene@CeO2 heterojunction solution.

[0044] Comparative Example 3 Prepare the MXene@CeO2 heterojunction solution as follows: (1) Dissolve 2.0 mmol Ti3AlC2MXene and 20 mmol LiF in 5 mL 9M HCl and allow to etch at room temperature for 24 hours. (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min; (3) The mixed solution after stripping was centrifuged at 3500 rpm, and then remixed. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected. (4) 5 mg of CeO2 and 5 mg of single-layer Ti3C2MXene nanosheets prepared in step (3) were ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0045] (5) Ultrasonic dispersion of 1 mg of MXene@CeO2 heterojunction in 1 mL of deionized water was performed to obtain a MXene@CeO2 heterojunction solution.

[0046] Comparative Example 4 Prepare the MXene@CeO2 heterojunction solution as follows: (1) Dissolve 1.5 mmol Ti3AlC2MXene and 15 mmol LiF in 5 mL 9 M HCl and allow to etch at room temperature for 24 hours. (2) The etched liquid was centrifuged to remove the upper acid solution, and then washed with deionized water until neutral, and then ultrasonically stripped at a power of 200 W for 30 min; (3) The mixed solution after stripping was centrifuged at 3500 rpm, and then remixed. This operation was repeated until the upper liquid turned black, and the single-layer Ti3C2MXene nanosheets in the upper clear liquid were collected. (4) 5 mg of CeO2 and 25 mg of single-layer Ti3C2MXene nanosheets prepared in step (3) were ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

[0047] (5) Ultrasonic dispersion of 1 mg of MXene@CeO2 heterojunction in 1 mL of deionized water was performed to obtain a MXene@CeO2 heterojunction solution.

[0048] Comparative Example 5 Prepare the composite hydrogel as follows: (1) 200 mg of GelMA-PBA and 1 mg of LAP were dissolved in 1 mL of deionized water to prepare GelMA-PBA microspheres by microfluidic technology; 100 mg of HA-DA was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0049] (2) Dissolve 200 mg of Gel-PBA in 1 mL of deionized water to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB in ​​1 mL of deionized water to obtain a HA-NB solution.

[0050] (3) Mix 100 mg of GelMA-PBA microspheres, 100 μL of HA-DA solution, 100 μL of Gel-PBA solution, and 100 μL of HA-NB solution. Use 1 M sodium hydroxide to adjust the pH value of the system to between 7 and 8. Inject the gelled hydrogel into the mold to form a composite hydrogel.

[0051] Comparative Example 6 The Janus structure hydrogel was prepared as follows: (1) 200 mg of GelMA-PBA and 1 mg of LAP were dissolved in 1 mL of deionized water to prepare GelMA-PBA microspheres by microfluidic technology; 100 mg of HA-DA was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0052] (2) Mix 100 mg of GelMA-PBA microspheres with 100 μL of HA-DA solution, adjust the pH value of the system to between 7 and 9 using 1 M sodium hydroxide, and inject the gelled microgel into the mold to form the Janus inner layer.

[0053] (3) Dissolve 200 mg of Gel-PBA in 1 mL of deionized water to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB in ​​1 mL of deionized water to obtain a HA-NB solution.

[0054] (4) The Gel-PBA solution and the HA-NB solution were mixed in a volume ratio of 1:1 to form a gel. The gelled hydrogel was injected into the mold to form the Janus outer layer. The two layers were bonded by hydrogen bonds to form a Janus structure.

[0055] Comparative Example 7 The Janus structure hydrogel was prepared as follows: (1) 200 mg of GelMA-PBA and 1 mg of LAP were dissolved in 1 mL of deionized water, and 1 mg of MXene@CeO2 heterojunction was added and ultrasonically dispersed uniformly. Microspheres loaded with MXene@CeO2 heterojunction were prepared by microfluidic technology; 100 mg of HA-DA was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0056] (2) 100 mg of MXene@CeO2 heterojunction-loaded microspheres were mixed with 100 μL of HA-DA solution, and the pH value of the system was adjusted to between 7 and 9 using 1 M sodium hydroxide. The gelled microgel was then injected into the mold to form the Janus inner layer.

[0057] (3) Dissolve 200 mg of Gel-PBA in 1 mL of deionized water to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB in ​​1 mL of deionized water to obtain a HA-NB solution.

[0058] (4) The Gel-PBA solution and the HA-NB solution were mixed in a volume ratio of 1:1 to form a gel. The gelled hydrogel was injected into the mold to form the Janus outer layer. The two layers were bonded by hydrogen bonds to form a Janus structure.

[0059] Comparative Example 8 The Janus structure hydrogel was prepared as follows: (1) 200 mg of GelMA-PBA and 1 mg of LAP were dissolved in 1 mL of deionized water to prepare GelMA-PBA microspheres by microfluidic technology; 100 mg of HA-DA was dissolved in 1 mL of deionized water to obtain HA-DA solution.

[0060] (2) Mix 100 mg of GelMA-PBA microspheres with 100 μL of HA-DA solution, adjust the pH value of the system to between 7 and 9 using 1 M sodium hydroxide, and inject the gelled microgel into the mold to form the Janus inner layer.

[0061] (3) Dissolve 200 mg of Gel-PBA in 1 mL of deionized water, add 1 mg of BaTiO3 and disperse it evenly by ultrasonication to obtain a Gel-PBA solution; dissolve 20 mg of HA-NB in ​​1 mL of deionized water to obtain a HA-NB solution.

[0062] (4) The Gel-PBA solution and the HA-NB solution were mixed in a volume ratio of 1:1 to form a gel. The gelled hydrogel was injected into the mold to form the Janus outer layer. The two layers were bonded by hydrogen bonds to form a Janus structure.

[0063] Test Case 1. Photothermal characterization Test method: MXene@CeO2 heterojunction solutions with different concentrations (0.25, 0.50, 0.75, and 1.00 mg / mL) were prepared and irradiated with 808 nm NIR laser for 10 minutes at a power of 1.0 W / cm 2 , use a thermocouple thermometer to record the real-time temperature, record the real-time temperature every 20 s, use time as the horizontal axis and temperature as the vertical axis, and plot the obtained data into a heating curve.

[0064] The test results are as follows Figure 1 As shown, it can be seen that with the increase of concentration, the photothermal effect becomes more significant, but after reaching a certain concentration, it tends to be stable, and there is little difference between 0.75 mg / mL and 1 mg / mL. Moreover, the MXene@CeO2 heterojunction synthesized in the embodiment of the present invention has good photothermal cycle performance.

[0065] 2. Antibacterial properties Test method: Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) After recovery, the cells were cultured to the logarithmic growth phase, centrifuged, and the bacteria were collected and resuspended in physiological saline. The final bacterial solution concentration was 1×10 8 CFU / mL. 1 mL of the samples of Examples 1-2 and Comparative Examples 1-8 was added to a 24-well plate, followed by 100 μL of the diluted bacterial suspension and 1 mL of sterile saline in each well. The plate was irradiated with an 808 nm NIR laser for 10 minutes at a power of 1.0 W / cm 2 , incubated at 37°C for 24 hours, spread on LB agar plates after gradient dilution, and counted. The control group was the normal saline group.

[0066] For scanning electron microscopy (SEM), 1 mL of cultured bacterial liquid was placed in a 1.5 mL centrifuge tube and centrifuged at 3500 rpm for 10 minutes. The supernatant was removed and the precipitate was retained. The bacterial precipitate obtained by centrifugation was dispersed with 1 mL of 2.5% glutaraldehyde and fixed for 2-3 hours. The fixed bacteria were centrifuged at 3500 rpm to obtain the precipitate, which was washed and dispersed in deionized water. 10-20 μL of the bacterial liquid dispersed in deionized water in the previous step was dropped onto a single crystal silicon wafer and air-dried. The naturally dried sample was attached to a copper stage with conductive adhesive, sprayed with gold for 90-120 seconds, and photographed.

[0067] For biofilm removal, the biofilm after culture was fixed with 500 μL of anhydrous methanol for 1 hour, and 200 μL of 1% crystal violet stain was added and placed in an incubator in the dark for 30 minutes. After that, the plate was washed several times with sterile water, and the culture plate was inverted on filter paper to remove residual water. After drying at room temperature, the plate was photographed.

[0068] The test results are shown in Table 1 and Figure 2 shown.

[0069] Table 1: Antibacterial rates of Examples and Comparative Examples

[0070] From Table 1 and Figure 2 It can be seen that the Janus structure hydrogel of Example 1 of the present invention has a good antibacterial effect, which is mainly achieved by CeO2. Further, under NIR irradiation, the MXene@CeO2 heterojunction of the present invention can also absorb photons, convert light energy into heat energy, increase the temperature of the infected wound site, cause bacterial death, and effectively destroy the biofilm produced by bacteria. This is related to the rapid release and contact surface of the Janus structure. The Janus structure hydrogel is in more complete contact with the bacteria. After NIR irradiation, the oxygen vacancies capture photogenerated electrons and enhance photothermal conversion, and the photothermal conversion efficiency can be significantly increased. The antibacterial rate of Example 2 is slightly lower than that of Comparative Examples 1-4, mainly because Comparative Examples 1-4 are directly cultured with heterojunctions. Example 2 loads the heterojunction in a physical mixed hydrogel. The antibacterial effect of the pure heterojunction is stronger than the antibacterial effect loaded into the gel, so the antibacterial rate of Example 2 is slightly reduced. Comparative Examples 5 and 6 are blank gels that do not contain antibacterial substances, so the antibacterial rate is low. Comparative Example 8 only loads the piezoelectric material BaTiO3, so the antibacterial effect is extremely weak.

[0071] 3. In vitro ROS scavenging Test method: H2O2 scavenging is to mix the sample with 1mM H2O2 and react in the dark for different time periods (0.5, 1, 3, 5, and 8 hours). The remaining H2O2 concentration is then detected using a H2O2 kit and the absorbance curve at a wavelength of 340-600 nm is detected using UV-visible spectroscopy.

[0072] The samples were reacted with the precursor solution in the hydroxyl radical (·OH) assay kit for various times (0.5, 1, 2, 4, 6, and 8 hours). The absorbance curve at wavelengths between 400 and 650 nm was measured using UV-visible spectroscopy. 0.4 mL of sample was added to 0.5 mL of 0.05 mol / L Tris-HCl buffer and the mixture was reacted in a 25°C water bath for 20 min. 0.1 mL of 10 mmol / L pyrogallol solution was then added and mixed. The mixture was then reacted in a 25°C water bath for various times (0.5, 1, 2, 4, 6, and 8 hours). The reaction was terminated by adding 0.1 mL of 10 M HCl. The absorbance curve at wavelengths between 260 and 500 nm was measured using UV-visible spectroscopy.

[0073] The test results are shown in Table 2.

[0074] Table 2: ROS scavenging efficiency of Examples and Comparative Examples

[0075] Table 2 shows the scavenging effect of Janus hydrogels on H2O2. After incubation of Janus hydrogels with H2O2 for various periods of time, the residual H2O2 concentration was measured using a H2O2 assay kit and a full-spectrum scan was performed using a UV-visible spectrophotometer. The results showed that the residual H2O2 concentration decreased, indicating that more H2O2 was scavenged.

[0076] Table 2 shows the Janus structure hydrogels for ·OH and O 2- Janus structure hydrogel with ·OH and O 2- After incubation with the precursor solution, the full spectrum of the incubated liquid was scanned. The results showed that the remaining ·OH and O 2- The concentration is low and it shows good active oxygen scavenging effect, which is mainly due to the crystal structure and variable oxidation state of MXene@CeO2 in Janus structure hydrogel. 4+ and Ce 3+ The redox couple cycle realizes the catalytic conversion of reactive oxygen species.

[0077] 4. Cytological evaluation Test method: Cultured L929 cells, HUVEC cells, and macrophages were trypsinized and suspended, then seeded into 48-well plates. After 12 hours of culture, the original culture medium was removed, and 1 mL of hydrogel sample was added to 10 mL of cell culture medium. The cells were incubated at 37°C for 24 hours to obtain an extract. The extract was then added and cultured for 24, 48, and 72 hours. The culture medium was aspirated, the cells were washed three times with PBS, CCK-8 stain was added, the cells were washed with PBS, and images were captured using a fluorescence microscope.

[0078] For in vitro macrophages, RAW264.7 cells were cultured at 1 × 10 6Cells were seeded at a density of 100 cells / well in a 6-well plate containing cell slides. After overnight culture, cells were induced with 5 μg / mL lipopolysaccharide (LPS) and then incubated in Janus hydrogel extract for 24 hours. After washing with PBS, cells were fixed with 1% paraformaldehyde for 15 minutes, washed one to two times with PBS, treated with permeabilization buffer for 10 minutes, washed one to two times with PBS, and blocked with 1% BSA blocking buffer for 30 minutes. Then, cells were incubated with rabbit anti-iNOS and mouse anti-CD206 fluorescent antibodies (1:200 dilution) at room temperature for 1 hour. After incubation, cells were washed twice with PBS and incubated with FITC goat anti-rabbit IgG and Cy3 goat anti-mouse IgG secondary antibodies at room temperature for 1 hour. After incubation, the slides were removed, mounted with DAPI-containing anti-fluorescence quencher, and observed and photographed under a fluorescence microscope.

[0079] Test results: As shown in Tables 3 and 4, it can be seen that the Janus structure hydrogel prepared in Example 1 of the present invention has good biocompatibility, promotes the polarization of macrophages to M2, exhibits good immunomodulatory effects in vitro, promotes the release of anti-inflammatory factors TGF-β1 and IL-4, and inhibits the secretion of pro-inflammatory factors TNF-α and IFN-γ.

[0080] Table 3: Cell viability of Examples and Comparative Examples

[0081] Table 4: Relative expression levels of inflammatory factors in Examples and Comparative Examples

[0082] 5. Repair effect of infected wounds Test method: After anesthesia, the rats were shaved from their backs and the exposed skin was disinfected. A full-thickness circular skin defect with a diameter of 12 mm was created using surgical scissors. Subsequently, a mixture of Escherichia coli and Staphylococcus aureus (1×10 8 CFU / mL) and fixed with 3M Tegaderm waterproofing agent for 24 hours to induce infection. Infected rats were randomly divided into experimental groups. The Janus hydrogel of Example 1 and the mixed hydorgel of Example 2 were placed in the wounds. Wound healing was observed 3, 7, 10, 14, and 21 days after surgery. The control group was treated with normal saline.

[0083] Test results: Figure 3As shown, photographs of infected wounds in rats from different groups were taken, and the healing traces of each wound were simulated and statistically analyzed. The results show that after 7 days of treatment with the Janus hydrogel, the wounds had clearly scabbed and healed. After 10 days of treatment, the wound area in the Janus hydrogel-treated group was significantly smaller than that in the blank group, and the results were superior to those of the physical hybrid hydrogel.

[0084] The wound tissue was then stained with HE and Masson staining. The results showed that the wound width was significantly reduced after treatment with Janus structure hydrogel, more collagen was deposited, and the repair effect was better.

[0085] Finally, the wound tissue was subjected to immunofluorescence staining. CD31 is a marker of new blood vessels, and it is obvious that the Janus structure hydrogel can effectively promote angiogenesis in the wound tissue.

[0086] The technical features of the above-described embodiments can be combined in any combination. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of this invention shall be based on the attached claims.

Claims

1. A method for preparing a Janus structured photothermal-piezoelectric hydrogel dressing for repairing infected wounds, characterized in that: The following steps are involved: (1) Phenylboronic acid-grafted methacrylamide gelatin and dopamine-grafted hyaluronic acid were dissolved in deionized water, and MXene@CeO2 heterojunction was added and ultrasonically dispersed uniformly. After mixing, the pH was adjusted to slightly alkaline using sodium hydroxide to form the inner layer of the Janus structure. (2) Phenylboronic acid grafted gelatin and o-nitrobenzyl alcohol grafted hyaluronic acid were dissolved in deionized water respectively, and BaTiO3 was added and ultrasonically dispersed evenly. After mixing, a Janus structure outer layer was formed.

2. The preparation method according to claim 1, characterized in that The MXene@CeO2 heterojunction is prepared by the following steps: S1. Ti3AlC2 MXene and LiF were dissolved in HCl for etching, washed to neutrality, and then exfoliated by ultrasonication. Single-layer Ti3C2 MXene nanosheets were then collected by centrifugation. S2. CeO2 and the monolayer Ti3C2 MXene nanosheet are ultrasonically dispersed in pure water to obtain a MXene@CeO2 heterojunction.

3. The preparation method according to claim 2, characterized in that In step S1, the Ti3AlC2 MXene:LiF:HCl = 1-2 mmol:10-20 mmol:3-10 mL, the HCl concentration is 5-11 mol / L, the etching time is 24-36 hours, the ultrasonic stripping power is 200-400 W, the ultrasonic stripping time is 30-60 min, and the collection centrifugal speed is 3000-5000 rpm.

4. The preparation method according to claim 2, characterized in that In step S2, the mass ratio of the CeO2 to the single-layer Ti3C2 MXene nanosheet is 1:1-1:5, and the ultrasonic dispersion time is 0.5-2 hours.

5. The preparation method according to claim 1, characterized in that In step S1, the concentration of the phenylboronic acid-grafted methacrylamide gelatin is 10%-30%, the concentration of the dopamine-grafted hyaluronic acid is 5%-15%, the concentration of the MXene@CeO2 heterojunction is 0.1-2.0 mg / mL, the concentration of sodium hydroxide is 0.5-2.0 M, and the pH range is 7-9.

6. The preparation method according to claim 1, characterized in that In step S2, the concentration of the phenylboronic acid grafted gelatin is 10%-30%, the concentration of the o-nitrobenzyl alcohol grafted hyaluronic acid is 1%-3%, and the concentration of BaTiO3 is 0.1-2.0 mg / mL.

7. The hydrogel dressing prepared by the method according to any one of claims 1 to 6.

8. Use of the hydrogel dressing according to claim 7 in preparing a wound repair product.

9. The use according to claim 8, characterized in that The wound surface includes any one or more of an infected wound surface, a diabetic wound surface, a burn wound surface and a complex wound surface.

10. Use of the hydrogel dressing according to claim 7 in preparing a product having the following effects: antibacterial; active oxygen scavenging; anti-inflammatory; and immunomodulatory.

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