A near-infrared responsive co-crystal hydrogel and a preparation method and application thereof

Abstract

The application discloses a near-infrared responsive eutectic gel, a preparation method and application thereof, wherein the eutectic gel is loaded with photo-thermal nanoparticles, and the surface of the photo-thermal nanoparticles is further modified with a CO donor; the photo-thermal nanoparticles generate a thermoelectric power under near-infrared stimulation to generate a centripetal direct current in the gel, and the CO donor releases CO through pyrolysis under the cascade reaction of the photo-thermal effect. The eutectic gel provided by the application can realize the three effects of centripetal direct current generation, photo-thermal antibiosis and CO controllable release under single near-infrared stimulation, and can improve the pathological microenvironment of an infected wound in multiple aspects, significantly improve the antibiosis, anti-inflammatory and regeneration effects, and accelerate the healing of the infected wound.

Description

Technical Field

[0001] This invention relates to the field of wound dressing technology, and in particular to a near-infrared responsive eutectic gel, its preparation method, and its application. Background Technology

[0002] Skin injuries are a common clinical condition, and their healing process involves complex physiological and pathological mechanisms. When skin integrity is compromised, the transepithelial potential (TEP) in the wound area becomes disordered, and the TEP is one of the key bioelectrical signals guiding cell migration and proliferation. Wound infection further exacerbates this disorder, causing persistent inflammatory stress, interfering with calcium ion signaling pathways, affecting angiogenesis, epithelial regeneration, and matrix remodeling, ultimately leading to the wound transitioning from an acute to a chronic, refractory state.

[0003] Therefore, an ideal wound dressing needs to have multiple functions, such as being able to reconstruct directional electrical stimulation similar to TEP, inhibiting bacteria, activating signaling pathways related to tissue regeneration, and adapting to irregular wound morphology.

[0004] Electrical stimulation therapy has been proven to reconstruct the TEP (transient electrical field) of wounds by applying an exogenous electric field, thereby promoting cell migration and proliferation and accelerating wound closure. However, most existing wearable self-powered devices suffer from problems such as heavy reliance on kinetic energy conversion and simple conductive pathways. The magnitude and direction of the generated current are often difficult to control precisely, and most rely on external power sources, which limits their convenience and efficacy in wound repair.

[0005] In addition, traditional thermoelectric nanomaterials operate in environments close to body temperature, but due to the limited temperature difference available on the skin surface, the generated current density is low, making it difficult to meet the needs of biomedical applications. At the same time, some thermoelectric nanomaterials have certain defects such as cytotoxicity and poor colloidal stability, making it difficult to apply them directly in the biomedical field.

[0006] On the other hand, photothermal therapy (PTT), as an antibacterial strategy that utilizes near-infrared (NIR) light to generate local heat, has advantages such as deep tissue penetration, broad antibacterial spectrum, and low likelihood of inducing drug resistance. Although PTT can kill bacteria and destroy biofilms, it is difficult to effectively regulate excessive inflammation and immune microenvironment imbalance in wounds, which is one of the core pathological factors of chronic wounds that are slow to heal.

[0007] At the materials science level, traditional hydrogel dressings are prone to increased resistance and decreased conductivity due to water evaporation under near-infrared irradiation, resulting in unstable treatment effects; while conventional ionic liquids have good conductivity, but poor biocompatibility, which limits their application in long-term wound contact.

[0008] In summary, there is currently a lack of a multifunctional integrated wound dressing that can achieve targeted electrical stimulation reconstruction, highly efficient antibacterial, anti-inflammatory, and immunomodulatory effects. Summary of the Invention

[0009] This invention provides a near-infrared responsive eutectic gel, its preparation method, and its application. The eutectic gel can generate a photothermal effect under near-infrared stimulation, and then provide a stable centripetal direct current and CO release effect through the cascade reaction generated by the photothermal effect, thereby synergistically achieving antibacterial, anti-inflammatory, and regenerative functions. It solves the problems of bioelectrical signal recovery, limited antibacterial effect, inability to improve inflammatory dysregulation, and slow wound healing in the prior art, and provides an efficient and multifunctional treatment strategy for the repair of infected wounds.

[0010] The present invention provides a near-infrared responsive eutectic gel, wherein the eutectic gel is loaded with photothermal nanoparticles, and the surface of the photothermal nanoparticles is further modified with a CO donor; the photothermal nanoparticles generate thermoelectric force under near-infrared stimulation, thereby generating a centripetal direct current inside the gel, and the CO donor releases CO through thermal decomposition under the cascade reaction of the photothermal effect.

[0011] Preferably, the photothermal nanoparticles have a mass fraction of 0.5-5% in the eutectic gel raw material.

[0012] Specifically, the preferred mass fraction of the photothermal nanoparticles in the eutectic gel raw material is 2%.

[0013] Preferably, the cumulative CO release of the photothermal nanoparticles under 808nm near-infrared irradiation is not less than 9 μM·mg.

[0014] Specifically, the cumulative CO release of the photothermal nanoparticles under secondary irradiation at 808nm near-infrared intensity is not less than 15μM·mg, and the duration of a single irradiation session is 3 min.

[0015] Specifically, the photothermal conversion efficiency of the photothermal nanoparticles is not less than 30%.

[0016] Preferably, the CO donor self-assembles and coats the surface of the metal nanoparticles through coordination to form photothermal nanoparticles with a core-shell structure; the metal nanoparticles are photothermal nanomaterials.

[0017] Preferably, the CO donor comprises a levodopa (L-DOPA) covalently linked to a transition metal carboxyl complex via an amidation reaction; the ligand of the transition metal carboxyl complex is CO, which triggers the pyrolysis of the transition metal carboxyl complex in the shell layer under near-infrared stimulation due to the photothermal effect, thereby achieving the in-situ release of CO gas in a near-infrared response. The transition metal carboxyl complex may be a ruthenium-based complex.

[0018] Preferably, the metal nanoparticles are layered Bi2Te3 nanoparticles with a particle size of 400-700 nm and a layer thickness of 20-50 nm.

[0019] The present invention provides a near-infrared responsive eutectic gel, wherein the raw materials of the eutectic gel also include deep eutectic solvent (DES), physiological saline, natural macromolecules, and polyvinyl alcohol (PVA).

[0020] Specifically, the natural macromolecules can be selected from one or more of gelatin, collagen, silk fibroin, and chitosan.

[0021] This invention provides a method for preparing a near-infrared responsive eutectic gel, the method comprising the following steps: Preparation of eutectic gel: Using a deep eutectic solvent-physiological saline composite solvent as the dispersion medium, photothermal nanoparticles, gelatin and polyvinyl alcohol are added to form a gel precursor solution; the gel precursor solution is poured into a mold and subjected to freeze-thaw cycle treatment to obtain the eutectic gel.

[0022] Specifically, the mass fraction of the deep eutectic solvent in the deep eutectic solvent-physiological saline composite solvent is 50-70%, preferably 60%.

[0023] Specifically, the preparation method further includes the preparation of a deep eutectic solvent, wherein ethylene glycol (EG) and 1-Butyl-3-methylimidazolium chloride (IL) are mixed at a molar ratio of 1.5-2.5:1 and stirred at 60°C until a homogeneous and transparent deep eutectic solvent (DES) is formed.

[0024] Specifically, the eutectic gel is prepared by a physical cross-linking freeze-thaw method, the mass fraction of polyvinyl alcohol in the eutectic gel raw material is 7.5-8.5%, and the freezing temperature of the freeze-thaw cycle is -20℃.

[0025] Specifically, the preparation method further includes the preparation of photothermal nanoparticles, which comprises the following steps: Layered Bi2Te3 nanoparticles were prepared by hydrothermal method or coprecipitation method; Synthesis of CO donor: The CO donor is a carbon monoxide release-dopamine conjugate (CO-DOPA); CO-DOPA is prepared by covalently linking L-DOPA with a transition metal carboxyl complex with CO as the ligand through an amidation reaction. Catechol-metal coordination: Synthesized CO-DOPA was self-assembled and coated onto the surface of Bi2Te3 nanoparticles to form core-shell structured photothermal nanoparticles (CO-Bi2Te3). This structure not only maintains the excellent photothermal and thermoelectric properties of Bi2Te3, but also endows the photothermal nanoparticles with the ability to release CO via near-infrared triggering.

[0026] This invention provides a near-infrared responsive eutectic gel. When the eutectic gel is applied to an infected wound, the following cascade reaction occurs under 808nm near-infrared light stimulation: Photothermal conversion and temperature difference establishment: Photothermal nanoparticles efficiently absorb light energy and convert it into heat energy, causing the temperature of the eutectic gel-wound interface to rise rapidly, establishing a significant radial temperature gradient between the wound center (hot zone) and the edge (cold zone). Thermoelectric current generation: Based on the Seebeck effect, the high concentration of free ions (Na+) in the eutectic gel... + ,Cl - Driven by a temperature gradient, certain molecules (such as α, β, and β) undergo directional migration, thereby generating a stable and continuous centripetal direct current within the eutectic gel, pointing from the cold region to the hot region. This current effectively simulates and repairs the damaged transepithelial potential. Carbon monoxide (CO) release: The local thermal effect generated by near-infrared stimulation simultaneously triggers the pyrolysis of carbonyl ruthenium ligands in the CO-DOPA shell, enabling on-demand, in-situ release of CO gas.

[0027] This invention provides the application of a near-infrared responsive eutectic gel in products that promote the healing of infected wounds.

[0028] This invention provides the application of a near-infrared responsive cocrystal gel in the preparation of products for repairing bioelectrically damaged tissues and organs.

[0029] The beneficial effects of the present invention: The eutectic gel provided by the present invention can achieve a triple effect of centripetal direct current generation, photothermal antibacterial and CO controllable release under single near-infrared stimulation, which improves the pathological microenvironment of infected wounds in many ways, significantly enhances antibacterial, anti-inflammatory and regenerative effects, and accelerates the healing of infected wounds.

[0030] The eutectic gel provided by this invention does not require a conductive power supply and can trigger multiple therapeutic functions simply by near-infrared light irradiation. It is easy to operate, not limited by wired circuits, and is suitable for the treatment of clinically infected wounds. It has broad application prospects and can be extended to the repair of other bioelectrically damaged tissues and organs.

[0031] The eutectic gel provided by this invention utilizes a near-infrared induced temperature gradient to generate a stable centripetal direct current, simulating endogenous TEP signals, effectively restoring the bioelectric polarity of the wound area, promoting the directional migration and proliferation of key skin cells, and providing important bioelectric signals for wound healing.

[0032] The eutectic gel provided by this invention combines photothermal effect and the antibacterial effect of CO, which can effectively destroy bacterial biofilms, kill drug-resistant bacteria, and is not prone to drug resistance, thus solving the problem that existing antibacterial dressings are difficult to eradicate mature biofilms; CO is released in a controlled manner through near-infrared induction, which can effectively inhibit excessive inflammatory response.

[0033] The eutectic gel provided by this invention has good biocompatibility. The surface modification of Bi2Te3 by DOPA group improves the biocompatibility. The eutectic gel matrix is ​​composed of DES, gelatin and PVA with excellent biocompatibility. In vitro and in vivo experiments have shown that it has no obvious toxicity and high biosafety.

[0034] The eutectic gel provided by this invention has good hydration stability, avoiding the performance degradation problem caused by dehydration under near-infrared irradiation of traditional hydrogels, and has stable photothermal stability and thermoelectric properties, and can be used for a long time. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the synthesis process of the CBD eutectic gel of the present invention.

[0036] Figure 2 This is a characterization diagram of the nanoparticles in Example 2. Figure 2 In the image, A represents the SEM images of Bi2Te3 and CO-Bi2Te3 (scale bar is 1 μm). Figure 2 B in the image represents the TEM images of Bi2Te3 and CO-Bi2Te3 (scale bar: 500 nm). Figure 2 In the figure, C represents the single-element distribution of Bi, Te, C, O, and Ru as analyzed by SEM (scale bar is 1 μm).

[0037] Figure 3 The high-resolution XPS spectra of Bi4f, Te3d, and Ru3d / 3p of Bi2Te3 and CO-Bi2Te3 in Example 2 are shown.

[0038] Figure 4 The temperature change curves are for the photothermal performance tests of each particle in Example 2.

[0039] Figure 5 The image shows the photothermal cycle curve of CO-Bi2Te3 in Example 2.

[0040] Figure 6The cumulative CO release of CO-Bi2Te3 in Example 2 is statistically significant.

[0041] Figure 7 The graph shows the rheological properties of each group of eutectic gels in Example 3. Solid circles represent storage modulus G', and hollow circles represent loss modulus G". Figure 7 In the figure, A represents the change in the rheological properties of each group of eutectic gels over time; Figure 7 In the figure, B represents the change in rheological properties of each group of eutectic gels with frequency; Figure 7 In the figure, C represents the change of rheological properties of each group of eutectic gels with temperature; Figure 7 In the figure, A represents the change in rheological properties of each group of eutectic gels with strain.

[0042] Figure 8 The figure shows the experimental results of the thermoelectric output performance of each group of eutectic gels in Example 3. Figure 8 In the figure, A represents the statistical results of the conductivity values ​​of each group of eutectic gels. Figure 8 B, C, and D in the table represent the statistical results of the output current, output voltage, and output power of each group of eutectic gels under different temperature differences; Figure 8 In this context, E and F represent the Seebeck coefficient and power factor of each group of eutectic gels. Figure 8 In this context, G represents the current response under NIR-induced thermal stimulation. Figure 8 H in the figure represents the statistical results of the relative response current change during repeated photothermal-electric switching cycles.

[0043] Figure 9 The results are the quantitative analysis results of the hemolysis rate of each group of eutectic gels (D, BD, CBD) in Example 4. Group I is dd water.

[0044] Figure 10 The results are the quantitative analysis results of cell viability of each group of cocrystallized gels in Example 4.

[0045] Figure 11 These are experimental images of the Transwell experiment and scratch healing experiment in Example 4. Figure 11 In the figure, A represents the Transwell migration experiment results, and the scale bar is 100 μm. Figure 11 B in the figure represents the results of the scratch healing experiment, and the scale bar is 100 μm.

[0046] Figure 12 For each group in Example 5 (with and without NIR irradiation) E. coli and S.aureus Image of colony-forming unit (CFU) plate results.

[0047] Figure 13 The results are the quantitative analysis of bacterial survival rate based on CFU analysis in Example 5. Figure 13 A in the text is S.aureus Quantitative analysis results of survival rate Figure 13 B in the text is E. coli Quantitative analysis results of survival rate.

[0048] Figure 14 For each group in Example 5 (with and without NIR irradiation) of E. coli and S.aureus Quantitative analysis results of biofilm biomass.

[0049] Figure 15 This is a schematic diagram of the animal experiment process in Example 6.

[0050] Figure 16 The wound records for each group in Example 6 were taken on postoperative days 0, 3, 6, 9, and 12. Figure 16 In the figure, A represents the wound photos of each group on postoperative days 0, 3, 6, 9, and 12. Figure 16 B in the diagram is a schematic representation of the wound boundaries for each group.

[0051] Figure 17 This is a temperature-time curve of the wounds in each group on day 0 in Example 6.

[0052] Figure 18 The results show the relative bacterial survival rates of the wound bacterial culture plate cultured on days 3 and 6 in Example 6.

[0053] Figure 19 This is a stained image of the wound tissue from Example 6. Wherein, Figure 19 In the figure, A represents the H&E staining results of wound tissue on day 3 and day 12, with a scale bar of 2 mm; Figure 19 B in the figure represents the Masson trichrome staining results of wound tissue on days 3 and 12, with a scale bar of 2 mm.

[0054] P<0.05, ** P<0.01, *** P<0.001 indicate that the difference is statistically significant. Detailed Implementation

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0056] All conventional reagents used in this invention were commercially available; human umbilical vein endothelial cells were provided by the Cell Bank of the Chinese Academy of Sciences; the PBS buffer concentration used in each example was 1X and the pH was 7.4.

[0057] The mice used in this invention were SPF-grade female SD rats provided by the Experimental Animal Center of Wenzhou Medical University. All animal procedures were performed in accordance with the Guidelines for the Care and Use of Experimental Animals of Wenzhou Medical University and were approved by the Animal Ethics Committee of Wenzhou Medical University.

[0058] Example 1: Preparation of Experimental Materials 1.1 Preparation of photothermal nanoparticles (CO-Bi2Te3) Layered Bi2Te3 nanoparticles were prepared by coprecipitation method; 2 mmol Bi(NO3)3・5H2O, 3 mmol Na2TeO3, 0.1 mol NaOH and 0.235 g polyvinylpyrrolidone (PVP) were dissolved in 80 mL ethylene glycol, stirred at 500 rpm and 180 °C for 24 h, and obtained by centrifugation and washing.

[0059] Synthesis of carbon monoxide-releasing dopamine conjugate (CO-DOPA): The tricarbonyl ruthenium(II) trichlorotrichlorodimer [Ru(CO)3Cl2]2 and L-DOPA were dissolved in anhydrous methanol at a molar ratio of 1:2. Sodium methoxide was added under nitrogen protection as a catalyst, and the reaction was carried out at room temperature in the dark for 18 h. The mixture was then evaporated to dryness to obtain CO-DOPA.

[0060] Catechol-metal coordination: 0.1 g of layered Bi2Te3 nanoparticles were dispersed in 20 mL Tris-HCl (10 mM, pH 8.5), 0.04 g CO-DOPA was added, and the mixture was stirred at 25 °C for 8 h. After centrifugation and purification, photothermal nanoparticles with a core-shell structure (CO-Bi2Te3) were obtained.

[0061] 1.2 Preparation of CBD eutectic gel Preparation of deep eutectic solvent: Ethylene glycol (EG) and 1-Butyl-3-methylimidazolium chloride are mixed in a molar ratio of 2:1 and stirred at 60°C until a homogeneous and transparent deep eutectic solvent (DES) is formed.

[0062] Preparation of eutectic gel: A composite solvent with a mass ratio of 6:4 was prepared using 6 g of deep eutectic solvent and 4 g of physiological saline as a composite dispersion medium. 2.0 g of gelatin and 1.0 g of PVA were added, along with 0.265 g of CO-Bi2Te3 (accounting for 2% of the total raw material mass). The above mixture was stirred at 95℃ and 500 rpm for 12 h to ensure that all components were fully dissolved and uniformly dispersed, forming a gel precursor solution. The gel precursor solution was poured into a mold and subjected to multiple freeze-thaw cycles at -20℃ to obtain a eutectic gel loaded with photothermal nanoparticles (CO-Bi2Te3).

[0063] 1.3 Preparation of BD eutectic gel The BD eutectic gel was prepared according to the method in 1.2. The difference between the BD eutectic gel and the CBD eutectic gel is that the Bi2Te3 nanoparticles prepared in 1.1 are used to replace the CO-Bi2Te3 in the preparation process of the eutectic gel in an equal amount.

[0064] 1.4 Preparation of D eutectic gel D eutectic gel was prepared according to the preparation method in 1.2. The difference between D and CBD is that CO-Bi2Te3 was not added during the preparation of the eutectic gel.

[0065] Preparation of 1.5-day eutectic gel The d-eutectic gel was prepared according to the preparation method in 1.2. The difference between the d-eutectic gel and CBD is that CO-Bi2Te3 is not added during the preparation of the eutectic gel, and the physiological saline in the eutectic gel raw material is replaced with an equal mass of double-distilled water (dd water).

[0066] Example 2: Particle Performance 2.1 Characterization of Particles The microstructures of Bi₂Te₃ and CO-Bi₂Te₃ nanoparticles were observed and analyzed using transmission electron microscopy and scanning electron microscopy. The particle size of Bi₂Te₃ was found to be 400-700 nm, and the lamellar thickness was 20-50 nm. Figure 2 As shown, both Bi2Te3 and CO-Bi2Te3 are layered nanoparticles, and a shell structure can be observed on the surface of CO-Bi2Te3.

[0067] SEM (Scanning Electron Microscopy) energy-dispersive X-ray spectroscopy (EDS) analysis was performed on CO-Bi2Te3. The EDS results are as follows: Figure 2 As shown in C, each element is uniformly distributed on the particle surface.

[0068] X-ray photoelectron spectroscopy (XPS) analysis of the particles yielded the following Bi4f, Te3d, and Ru3d / 3p spectra of Bi2Te3 and CO-Bi2Te3: Figure 3 As shown, this demonstrates the successful preparation of Bi2Te3 and CO-Bi2Te3 nanoparticles.

[0069] 2.2 Photothermal performance test of particles Photothermal Performance Experiment I: CO-DOPA, Bi₂Te₃, and CO-Bi₂Te₃ samples were dispersed in PBS buffer to prepare homogeneous dispersions of 2 mg / mL. 1.5 mL of each dispersion was placed in a centrifuge tube and vertically irradiated with an 808 nm near-infrared laser at a power density of 2.0 W / cm² for 180 s. Real-time temperature changes were observed using a FLIR infrared imager, with thermal images captured every 30 s. Temperature change curves were recorded and plotted. Figure 4 As shown, CO-DOPA, Bi2Te3, and CO-Bi2Te3 particles all exhibit near-infrared responsive photothermal effects.

[0070] Photothermal Performance Experiment II: CO-Bi₂Te₃ was dispersed in PBS buffer to a concentration of 2 mg / mL. A "light-cooling" experiment was conducted for 5 cycles using an 808 nm near-infrared laser (2.0 W / cm²). Each illumination period lasted 180 s, followed by natural cooling to room temperature. The temperature change curves for each cycle were recorded, and the results were statistically analyzed. Figure 5 As shown in the figure. The results indicate that CO-Bi2Te3 particles exhibit good photothermal cycling stability, and their photothermal performance does not significantly decrease after multiple cycles.

[0071] According to the photothermal conversion efficiency formulas (1)-(3), the photothermal conversion efficiency η of CO-Bi2Te3 is calculated to be 38.10%.

[0072] (1) (2) (3) in, I For laser power, A 808 This represents the absorbance of the aqueous suspension at 808 nm. T max1 The highest temperature induced by the sample. T max2 The highest temperature induced by water. T surr The ambient temperature is given; Q0 is the baseline heat absorbed by the solvent and container; h is the heat transfer coefficient; s is the surface area of ​​the container; m d For the mass of the sample dispersion, C d τ is the specific heat capacity of the dispersion. s is the time constant.

[0073] 2.3 CO emission performance of particles CO-Bi2Te3 was dispersed in PBS buffer to prepare a concentration of 2 mg / mL, and placed in a sealed reaction bottle at a constant temperature of 37°C. The solution was irradiated with an 808 nm near-infrared laser at a power density of 2 W / cm², and the CO concentration in the solution was measured by a carbon monoxide-specific electrode, and the cumulative release was calculated.

[0074] like Figure 6 As shown, after 3 minutes of stimulation with 808nm near-infrared light, the CO in the CO-Bi2Te3 group could exceed 9μM·mg. Further near-infrared irradiation (minutes 6-9) resulted in continuous CO release, reaching 15.2μM·mg.

[0075] Example 3 Characterization of eutectic gel 3.1 Rheological properties of eutectic gels The rheological properties of the four eutectic gels (d, D, BD, CBD) in Example 1 were tested. d is a eutectic gel without saline, D is a eutectic gel with saline, BD is a eutectic gel with saline and Bi2Te3 nanoparticles, and CBD is a eutectic gel with saline and CO-Bi2Te3.

[0076] The rotational rheometer was used for testing. Parallel plates of 20 mm diameter were selected with a plate spacing of 1 mm, and the temperature was controlled at 25℃. The following four tests were performed on each group of samples: Time-scan test: With strain set at 1% and frequency at 1 Hz, the changes in storage modulus (G') and loss modulus (G") were continuously recorded over 300 s to evaluate the structural stability of the gel; Frequency scanning test: With a strain of 1%, the gel is scanned in the frequency range of 0.1–100 rad / s to analyze the elastic response and cross-linking network strength. Strain scanning test: The frequency was set to 1 Hz, and the strain range of 0.1%–1000% was scanned to determine the linear viscoelastic region and critical yield strain of the gel. Temperature scan test: With strain set at 1% and frequency at 1 Hz, the temperature was increased from 25 ℃ to 60 ℃ at a heating rate of 2 ℃ / min. The changes of G' and G” with temperature were recorded to evaluate the thermal stability of the gel.

[0077] like Figure 7 As shown, compared with other eutectic gels, CBD gel has a significantly higher storage modulus (G') and is always greater than the loss modulus (G') across the entire frequency and strain range, exhibiting more stable elastic behavior. At the same time, it has a larger critical yield strain and a slower modulus decay during temperature scanning, indicating that the gel has a denser cross-linked network, stronger deformation resistance and better thermal stability, and can maintain a stable gel structure in the wound environment.

[0078] 3.2 Thermoelectric properties of eutectic gels Thermoelectric output performance experiments were conducted on the four eutectic gels (d, D, BD, CBD) in Example 1.

[0079] Temperature difference-induced thermoelectric performance test: Each group of eutectic gels was prepared into discs with a diameter of 5 mm and a thickness of 1 mm. Conductive copper foils were symmetrically attached to both sides of the gel as working electrodes. The electrodes were tightly attached to the gel interface to reduce contact resistance. The samples were placed on a controllable temperature difference test platform, with one side controlled as the low temperature end (25 ℃) and the other side as the high temperature end (30-55 ℃), forming a radial temperature gradient of ΔT=5-30 K. The output voltage, output current and output power under different temperature differences were recorded simultaneously using an electrochemical workstation, and thermoelectric performance curves were plotted.

[0080] Near-infrared response centripetal current test: Conductive copper foil was attached as working electrodes at the center point of laser irradiation and the edge of the gel. The electrodes were tightly attached to the gel interface to reduce contact resistance. The gel sample was placed on an insulating substrate and the central region of the gel was vertically irradiated with an 808 nm near-infrared laser (2 W / cm²) (forming a radial temperature gradient between a high-temperature central region and a low-temperature edge region). The instantaneous current signal within 0-180s was recorded using an electrochemical workstation, and the current direction was determined by the current direction. At the same time, five "near-infrared irradiation-natural cooling" cycles were set to evaluate the stability of thermoelectric performance.

[0081] like Figure 8 As shown, compared to other eutectic gels, CBD eutectic gel exhibits higher output voltage and output current at the same temperature difference, and its output power density is significantly improved. Under near-infrared irradiation, a stable radial temperature gradient is formed between the gel center and the edge. Based on the Seebeck effect, free ions (Na+) within the gel... + Cl - The directional migration forms a centripetal direct current from the low-temperature edge to the high-temperature center. The current intensity increases with the increase of the temperature gradient, and the performance does not decay significantly after multiple cycles, proving that the CBD eutectic gel has excellent near-infrared responsive thermoelectric output performance and stable centripetal current generation capability.

[0082] Example 4: Biocompatibility of the Material 4.1 Biocompatibility of the particles Human umbilical vein endothelial cells (HUVECs) were treated with high-glucose DMEM medium containing different concentrations (0-8 wt%) of CO-Bi2Te3 for 24 hours. Then, they were stained with CCK-8 reagent kit and the absorbance was measured. The results showed that within the range of WT≤8%, CO-Bi2Te3 had no significant effect on the survival rate of HUVECs, and the cell survival rate of each group was higher than 90%.

[0083] 4.2 Biocompatibility of the gel The hemolysis experiment was conducted in the following groups: I: Control group (dd water), II: D group (D cocrystal gel extract), III: BD group (BD cocrystal gel extract), IV: CBD group (CBD cocrystal gel extract); the cocrystal gel samples were immersed in sterile PBS buffer at a ratio of 0.1 g / mL. Red blood cells were allowed to react statically in each group for 2 hours, photographed, and the hemolysis rate of each group was recorded. Figure 9 As shown, except for the control group, no obvious hemolysis was observed in the eutectic gels of any group.

[0084] HUVEC cells were subjected to cell viability and cytotoxicity assays using the Calcein / PI Cell Viability and Cytotoxicity Assay Kit (Beyotime). The cells were divided into the following groups: I: PBS group; II: D group (D cocrystal gel extract); III: BD group (BD cocrystal gel extract); IV: CBD group (CBD cocrystal gel extract). Cocrystal gel samples were immersed in sterile PBS buffer at a concentration of 0.1 g / mL. Cell compatibility among the different groups was assessed using AM / PI staining results, and cell viability was statistically analyzed. Figure 10 As shown in the figure, the results showed no significant difference in HUVEC cell viability among different groups, demonstrating that the CBD cocrystal gel has good biocompatibility.

[0085] The effects of CBD+NIR on HUVEC cell migration were evaluated using Transwell and scratch wound healing assays. The Transwell assay procedure was as follows: HUVEC cells were grouped as in the live / dead staining assay at 2 × 10⁶ cells / cells. 5 Cells were seeded in the upper chamber of a Transwell chamber at a concentration of 600 μl of cocrystal gel extract (0.1 g / mL, prepared in PBS) according to their groupings in the lower chamber. The experimental groups were irradiated with 808 nm near-infrared light for 3 min every 3 hours after seeding, with a power density of 2 W / cm². After 24 h of culture, the unmigrated cells in the upper chamber were discarded, fixed with methanol, stained with crystal violet, and observed under a microscope.

[0086] The scratch healing assay was performed as follows: HUVEC cells were seeded into culture plates and, when the cells reached over 90% confluence, were evenly scratched with a pipette tip. Floating cells were washed away with PBS. According to the grouping, 1 ml of cocrystal gel extract (0.1 g / mL, prepared with PBS) was added to each well of a 12-well plate. The experimental groups were irradiated with 808 nm near-infrared light for 3 min every 3 hours after seeding, at a power density of 2 W / cm². The scratch width was recorded at 0 h and 24 h, and the scratch healing rate was calculated.

[0087] like Figure 11As shown, the cell migration ability of the CBD+NIR group was significantly enhanced; the calculated 24-hour scratch healing rate of the CBD+NIR group reached 72.74%.

[0088] Example 5: Antibacterial properties of eutectic gel The groups were set up as follows: I: PBS group, II: D group (D cocrystal gel), III: BD group (BD cocrystal gel), IV: CBD group (CBD cocrystal gel); each group was further divided into two treatment methods: near-infrared irradiation (NIR+) and no near-infrared irradiation (NIR-).

[0089] Staphylococcus aureus (S. aureus) S.aureus ATCC25923) and Escherichia coli ( E. coli The test strain (ATCC25922) was used, and the experimental steps were as follows: Preparation of bacterial culture: The standard strain was inoculated into LB liquid medium and cultured at 37°C with shaking for 12 h. The bacterial culture concentration was adjusted to 1.5×10^6 CFU / mL and set aside for later use.

[0090] Antibacterial treatment: Take 400 μL of the above bacterial solution and add 100 μL of PBS, D gel extract, BD gel extract, and CBD gel extract, respectively. The extract concentration is 0.1 g / mL. Mix well. The NIR+ group is irradiated with an 808 nm near-infrared laser at a power density of 2 W / cm² for 3 min. The NIR- group is not subjected to light treatment.

[0091] Colony counting: The bacterial suspensions of each group were serially diluted, and 100 μL of the diluted solution was evenly spread on LB solid medium and incubated at 37℃ for 12 h. The number of colonies was counted and the bacterial survival rate was calculated.

[0092] Biofilm structure observation: Bacteria were inoculated into confocal dishes and cultured for 48 h to form mature biofilms. The biofilms were then treated with PBS, D gel, BD gel, and CBD gel extracts, respectively. The NIR+ group was irradiated with 808 nm near-infrared light for 10 min. After incubation at 37℃ for 12 h, the biofilm viability was observed and the biofilm biomass was quantitatively analyzed using SYTO 9 / PI fluorescence staining and laser scanning confocal microscopy.

[0093] Culture results as follows Figure 12 As shown, the antibacterial and antibiofilm effects of each group of cocrystal gels were evaluated by observing biofilm structure through colony forming unit (CFU) counting and laser scanning confocal microscopy (CLSM). Figure 13 As shown, under near-infrared laser stimulation, the CBD+NIR group exhibits strong bactericidal effects against both types of bacteria, making... S.aureus The survival rate dropped to 4.01%. E. coliThe survival rate decreased to 4.74%; the CBD group without near-infrared laser stimulation did not show a strong bactericidal effect, proving that CO can be released in a controlled manner through near-infrared induction, which can effectively inhibit excessive inflammatory response; the quantitative analysis results of biofilm biomass in each group are as follows: Figure 14 As shown, compared to other groups, the CBD+NIR group can effectively disrupt bacterial biofilms, making... S.aureus The survival rate dropped to 33.21%. E. coli The survival rate dropped to 50.83%.

[0094] Example 6 Infected Wound Healing Experiment 6.1 Establishment of animal models and sample collection Twenty-four healthy female SD rats aged six weeks were randomly divided into four groups: I: PBS group, II: D group (D cocrystal gel), III: BD+NIR group (BD cocrystal gel + near-infrared), and IV: CBD+NIR group (CBD cocrystal gel + near-infrared), with n=6 in each group.

[0095] The experimental procedure is as follows Figure 15 As shown, on day 0: a full-thickness skin defect with a diameter of 8 mm was prepared on each side of the spine, and 0.2 mL of [unspecified substance] was added. S.aureus bacterial solution (10) 8 (CFU / mL), Groups II, III, and IV were covered with 8*8mm D cocrystal gel, BD cocrystal gel, and CBD cocrystal gel, respectively. Among them, Groups III and IV were irradiated with 808nm near-infrared light twice a day, for 3 minutes each time, with a 3-minute interval.

[0096] Sample collection: Photos of the wound were taken on days 0, 3, 6, 9, and 12. On day 0, wound temperature changes were monitored using an infrared thermal imager during near-infrared light irradiation (0-180s). On days 3 and 6, the wound was scraped with sterile cotton swabs, and bacteria were extracted from the swabs with 1 mL of sterile PBS. After extraction, the bacteria were evenly spread on nutrient agar plates. The agar plates were then inverted and placed in a 37 ℃ incubator for 12 h. Afterward, photos were taken, and the number of colonies was counted.

[0097] Wound tissue was collected on days 3 and 12. Specifically, after anesthetizing the mice, the wound tissue was perfused with PBS and then excised to prepare for subsequent histological evaluation.

[0098] 6.2 Experimental Results The temperature statistics of infected wounds in each group on day 0 are as follows: Figure 17 As shown, during near-infrared light irradiation, the wound temperature in group IV can reach 48.7℃.

[0099] like Figure 16The wound healing speed statistics shown indicate that, compared to other groups, Group IV's wound healing speed was significantly faster, with a healing rate of 99.57% on day 12.

[0100] like Figure 18 The statistical results of the bacterial suspension coatings shown indicate that group IV exhibits excellent photothermal antibacterial effects, with the bacterial survival rate dropping to below 1% on day 6.

[0101] like Figure 19 The H&E and Masson trichrome staining results shown indicate that in group IV, inflammatory infiltration was reduced, granulation tissue formation and collagen deposition were increased, and epithelial regeneration and angiogenesis were enhanced.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A near-infrared responsive eutectic gel, characterized in that, The eutectic gel is loaded with photothermal nanoparticles, and the surface of the photothermal nanoparticles is also modified with a CO donor. Under near-infrared stimulation, the photothermal nanoparticles generate thermoelectric force based on the Seebeck effect, forming a centripetal direct current from the cold region to the hot region inside the gel. The CO donor releases CO through thermal decomposition under the cascade reaction of the photothermal effect.

2. The near-infrared responsive eutectic gel according to claim 1, characterized in that, The photothermal nanoparticles have a mass fraction of 0.5-5% in the raw material of the eutectic gel.

3. The near-infrared responsive eutectic gel according to claim 1, characterized in that, The cumulative CO release of the photothermal nanoparticles under 808nm near-infrared irradiation is not less than 9 μM·mg.

4. The near-infrared responsive eutectic gel according to claim 1, characterized in that, The CO donor self-assembles and coats the surface of the metal nanoparticles through coordination to form photothermal nanoparticles with a core-shell structure; the metal nanoparticles are photothermal nanomaterials.

5. The near-infrared responsive eutectic gel according to claim 1, characterized in that, The CO donor comprises a levodopa-transition metal carboxyl complex covalently linked by an amidation reaction; the ligand of the transition metal carboxyl complex is CO.

6. The near-infrared responsive eutectic gel according to claim 3, characterized in that, The cumulative CO release of the photothermal nanoparticles under 808nm near-infrared irradiation is not less than 15 μM·mg.

7. The near-infrared responsive eutectic gel according to claim 4, characterized in that, The metal nanoparticles are layered Bi2Te3 nanoparticles with a particle size of 400-700 nm and a layer thickness of 20-50 nm.

8. The near-infrared responsive eutectic gel according to claim 1, characterized in that, The raw materials for the eutectic gel also include deep eutectic solvent, physiological saline, natural macromolecules, and polyvinyl alcohol.

9. A method for preparing a near-infrared responsive eutectic gel according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: Preparation of eutectic gel: Using a deep eutectic solvent-physiological saline composite solvent as the dispersion medium, photothermal nanoparticles, gelatin and polyvinyl alcohol are added to form a gel precursor solution; the gel precursor solution is poured into a mold and subjected to freeze-thaw cycle treatment to obtain the eutectic gel.

10. The application of a near-infrared responsive eutectic gel according to any one of claims 1-8, characterized in that, Application of the eutectic gel in products that promote wound healing in infected areas.

Images