Composite hydrogel with photothermal effect and preparation method and application thereof

Abstract

The present invention belongs to the technical field of composite hydrogels, and relates to a composite hydrogel with a photothermal effect, a preparation method thereof, and an application thereof. The composite hydrogel with a photothermal effect provided by the present invention is a skin-core structure, comprising natural bacterial cellulose and a photothermal water gel; wherein the natural bacterial cellulose is a core layer, and the photothermal water gel is a cortex. The composite hydrogel can maintain the three-dimensional network structure of the bacterial cellulose after freezing and thawing, and has good elasticity and tensile properties, solving the problems of inelasticity and non-adhesion of bacterial cellulose when used as a dressing. The composite hydrogel provided by the present invention is applied to skin wound repair, so that it can improve the secondary damage caused to the wound during the process of changing the wound dressing, and balance and regulate the temperature at the wound during laser irradiation, without the problem of local high temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite hydrogels, and more specifically, relates to a composite hydrogel with photothermal effect, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogel is a type of extremely hydrophilic three-dimensional network structure gel that can swell in water and retain a large amount of water without dissolving. Therefore, a large number of hydrogels are used in facial masks and wound dressings.

[0003] Bacterial cellulose (BC) is a nanosized cellulose produced by Acetobacter xylinum during its production and motility. Compared to other celluloses, BC has been extensively studied and applied in biomedical applications such as wound repair, artificial blood vessels, sustained-release drug delivery vehicles, and neural interfaces due to its high water-holding capacity, low immunogenicity, and excellent biocompatibility and mechanical properties. In particular, in the wound repair field, BC, due to its high water-holding capacity, is an excellent material for facial masks and wound dressings. However, many current functional modifications of BC require dissolving natural bacterial cellulose (nBC), adding functional materials to impart the desired properties, and then adding crosslinkers to produce regenerated bacterial cellulose (rBC). This approach, however, results in rBC that loses the three-dimensional network structure and certain mechanical properties of nBC, negating its advantages. Furthermore, natural bacterial cellulose lacks adhesiveness and cannot adhere to wound surfaces, limiting its application as a dressing.

[0004] Adhesive materials are used together with bacterial cellulose to prepare composite materials with adhesive properties, so that the composite materials with bacterial cellulose adhere and fix around the wound surface. For example, polydopamine (PDA) has excellent adhesive and photothermal properties and is widely used in the preparation of various adhesive hydrogels and photothermal hydrogels. However, the adhesive hydrogel is in direct contact with the wound surface and may tear the wound surface when changing the dressing. At the same time, when using ordinary single hydrogels with photothermal effects, although they have the effect of promoting the proliferation of fibroblasts and vascular cells, the temperature of ordinary photothermal hydrogels is the highest in the middle during photothermal treatment, or the long laser irradiation time causes the hydrogel to lose water and thus the temperature is unstable, resulting in local overheating of the wound surface, causing secondary damage such as bleeding and inflammation of the wound surface.

[0005] In summary, how to maintain the natural structure of bacterial cellulose and functionalize it, solve the problem that natural bacterial cellulose cannot be fixed on the wound surface as a dressing, and solve the problem of secondary damage to the wound by hydrogels with adhesive and photothermal properties are problems that technical personnel in this field urgently need to solve. Summary of the Invention

[0006] In view of the above defects or improvement needs of the prior art, the purpose of the present invention is to provide a composite hydrogel with photothermal effect, and its preparation method and application. The composite hydrogel with photothermal effect provided by the present invention is a skin-core structure, which is formed by surrounding the natural bacterial cellulose with a photothermal hydrogel and wrapping the natural bacterial cellulose. The composite hydrogel can maintain the three-dimensional network structure of natural bacterial cellulose after freezing and thawing, and has good elasticity and tensile properties, which solves the problem of inelasticity and non-adhesion of natural bacterial cellulose when used as a dressing. The composite hydrogel provided by the present invention can be used for skin wound repair, so that it can improve the secondary damage to the wound caused by the process of changing the wound dressing, and balance and regulate the temperature at the wound during laser irradiation, without the problem of local high temperature.

[0007] In a first aspect of the present invention, a composite hydrogel with a photothermal effect is provided. The composite hydrogel has a skin-core structure and comprises natural bacterial cellulose and a photothermal hydrogel; wherein the natural bacterial cellulose is a core layer and the photothermal hydrogel is a skin layer.

[0008] As a preference of the present invention, the natural bacterial cellulose is in a swelling equilibrium state.

[0009] As a preferred embodiment of the present invention, the thickness of the natural bacterial cellulose and the photothermal water gel are both 1 to 10 mm, preferably 3 mm.

[0010] As a preferred embodiment of the present invention, the photothermal water gel comprises polydopamine, polyvinyl alcohol and water; wherein the water content of the photothermal water gel is 87.5-95wt%; the mass fraction of the polyvinyl alcohol in the photothermal water gel is 5-12.5wt%; and the polydopamine is prepared by oxidation of dopamine hydrochloride under alkaline conditions.

[0011] As a preferred embodiment of the present invention, the photothermal water gel comprises bacterial cellulose, bamboo charcoal and water, the mass volume ratio of the bacterial cellulose to water is 15g / L to 30g / L, and the mass volume ratio of the bamboo charcoal to water is 0.5g / L to 1g / L.

[0012] In a second aspect of the present invention, a method for preparing a composite hydrogel having a photothermal effect is provided, comprising the following steps:

[0013] S11: placing natural bacterial cellulose in deionized water to reach swelling equilibrium, cutting it into a predetermined shape, and placing it at the center of the bottom of the mold;

[0014] S12: Weigh dopamine hydrochloride and dissolve it in deionized water, adjust the pH to 8.0-8.8, and obtain a polydopamine solution; weigh polyvinyl alcohol powder and add it to the polydopamine solution, mix well, and adjust the pH to neutral to obtain a photothermal water gel solution;

[0015] S13: evenly distributing the photothermal water gel solution around the natural bacterial cellulose in the mold of step S11, freezing it at -10 to -80°C for 8 to 12 hours, and melting it to obtain a composite hydrogel.

[0016] As a preferred embodiment of the present invention, the concentration of dopamine hydrochloride is 0.019 g / L to 0.285 g / L.

[0017] In a third aspect of the present invention, a method for preparing a composite hydrogel having a photothermal effect is provided, comprising the following steps:

[0018] S21: placing natural bacterial cellulose in deionized water to reach swelling equilibrium, cutting it into a predetermined shape, and placing it at the center of the bottom of the mold;

[0019] S22: Lithium hydroxide: urea: deionized water are weighed in a weight ratio of 4.6:15:80.4 and fully dissolved to obtain a bacterial cellulose solvent; bacterial cellulose is weighed separately and blended into a homogenous slurry, and dried to form a bacterial cellulose powder; the bacterial cellulose powder and bamboo charcoal are dissolved in the solvent, mixed in an ice bath, and then placed in a -10°C environment to fully dissolve to obtain a photothermal water gel solution;

[0020] S23: adding glutaraldehyde to the photothermal water gel solution, mixing evenly, and then evenly arranging the solution around the natural bacterial cellulose in the mold in step S11, and leaving the solution at room temperature to prepare a composite hydrogel.

[0021] In a fourth aspect of the present invention, there is provided use of the composite hydrogel with photothermal effect as described in any one of the first aspects of the present invention for preparing a wound dressing or a drug release carrier.

[0022] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0023] (1) The composite hydrogel provided in the embodiment of the present invention has a skin-core structure, wherein the natural bacterial cellulose is the core layer, and the photothermal water gel is the skin layer. The composite hydrogel can still maintain the three-dimensional network structure of the natural bacterial cellulose after freezing and thawing, and has significantly improved elasticity and tensile properties compared to pure bacterial cellulose. Therefore, when the composite hydrogel of the present invention is used as a wound dressing, since the core layer of the natural bacterial cellulose of the composite hydrogel has no adhesion properties, it can improve the problem of tearing damage to the wound caused by the wound during the dressing change process; and since the natural bacterial cellulose is wrapped by the photothermal water gel and the natural bacterial cellulose has no photothermal properties, it can improve the problem of local high temperature in the center during laser irradiation.

[0024] (2) The natural bacterial cellulose in the embodiment of the present invention is a biomaterial with excellent biocompatibility and very low immunogenicity. A variety of cells can grow on it and it can inhibit the proliferation of scars. In addition, due to its good water retention, natural bacterial cellulose can absorb pus from the wound surface, reduce inflammatory reactions, and reduce the chance of infection. Moreover, natural bacterial cellulose has no photothermal properties. During the laser irradiation process, the temperature of the composite hydrogel can be adjusted to maintain a suitable temperature for the part of the wound in contact with the natural bacterial cellulose, thereby preventing adverse reactions caused by overheating of the wound. In addition to the above advantages, natural bacterial cellulose also has the advantage of not adhering to the wound, thus preventing secondary damage when changing the dressing.

[0025] (3) In the embodiment of the present invention, when the photothermal water gel is composed of dopamine and polyvinyl alcohol, PVA is a material with good biocompatibility and good elasticity and tensile properties. The PVA solution is converted into a PVA hydrogel with good elasticity and skin-friendliness through a "freeze-thaw" method without adding a cross-linking agent; dopamine hydrochloride generates polydopamine in an alkaline environment, and polydopamine gives the PVA hydrogel adhesion and photothermal properties. Under the irradiation of laser, the peripheral PVA part of the composite hydrogel is heated, and the wound repair is promoted by stimulating the normal skin around the wound.

[0026] When polyvinyl alcohol is combined with polydopamine, the resulting composite hydrogel exhibits both adhesion and photothermal properties on the periphery, with excellent elasticity and tensile properties, while retaining the characteristics of natural bacterial cellulose on the interior. When polyvinyl alcohol combined with polydopamine is preferably used as the photothermal hydrogel portion of the composite hydrogel, the composite hydrogel can be fixed around the wound surface without adhering to the wound during wound repair, while also lowering the temperature of the composite hydrogel center and the wound surface, preventing problems such as localized overheating at the wound surface during photothermal therapy.

[0027] (4) In the embodiments of the present invention, the concentration of dopamine hydrochloride is preferably 0.019 g / L to 0.285 g / L. For example, the concentration of dopamine hydrochloride is 0 g / L (0 mmol), 0.095 g / L (0.5 mmol), 0.190 g / L (1 mmol) or 0.285 g / L (1.5 mmol). As the concentration of dopamine hydrochloride increases, the amount of polydopamine generated under alkaline conditions increases, thereby increasing the photothermal conversion efficiency and the viscosity. Different concentrations can be selected as required to meet the needs as a thermotherapy for skin wounds. Preferably, 0.5 mmol has a suitable temperature and is not too hot. The difference in temperature rise between 1 mmol and 1.5 mmol after being used in the "composite" hydrogel is not as large as that between 0 to 0.5 mmol and 0.5 to 1 mmol.

[0028] (5) In the embodiment of the present invention, when the photothermal water gel is composed of bacterial cellulose and bamboo charcoal, firstly, the regenerated bacterial cellulose has some advantages that the natural bacterial cellulose does not have. The texture of the natural bacterial cellulose is dense, and many other materials and substances cannot be mixed into the interior. However, after the bacterial cellulose is dissolved, it can be mixed with other materials very evenly, and then re-crosslinked by a cross-linking agent to generate regenerated natural bacterial cellulose, the bacterial cellulose is functionalized, and the regenerated bacterial cellulose can obtain the desired functional properties; secondly, bamboo charcoal has a good photothermal conversion ability, and the nano-scale bamboo charcoal particles can be very evenly dispersed inside the cellulose, and the material properties are stable.

[0029] When regenerated bacterial cellulose and bamboo charcoal constitute the part of the photothermal hydrogel, the bamboo charcoal particles are evenly compounded in the bacterial cellulose solution, and the cross-linking at room temperature better maintains the effect of natural bacterial cellulose. In addition, the composite hydrogel has photothermal properties, which can convert light energy into heat energy not only in the near infrared but also in the far infrared, and the requirements for instruments in photothermal applications are lower.

[0030] (6) In an embodiment of the present invention, a composite hydrogel with a photothermal effect is formed by surrounding a natural bacterial cellulose with a photothermal hydrogel and encapsulating the natural bacterial cellulose. Without the use of any crosslinking agent, PVA and BC are crosslinked together by physical crosslinking. The resulting hydrogel can be used without washing, eliminating the potential hazards of crosslinker residue.

[0031] (7) In the embodiments of the present invention, when the composite hydrogel is used as a wound dressing, it can significantly reduce the secondary damage to the wound during dressing changes, and the problem of local high temperature on the wound surface during laser irradiation will not occur. At the same time, the composite hydrogel of the present invention can maintain the characteristics of the internal natural bacterial cellulose and the structure of the external photothermal hydrogel, so that the photothermal performance of the composite hydrogel is a uniform and suitable mild temperature during wound repair.

[0032] For example, it has obvious effects on the healing of acute and chronic wounds. By comparing the recovery of acute wounds and chronic wounds, the photothermal properties of the photothermal water gel part of the composite hydrogel play a very obvious effect in the recovery of acute wounds; while the natural bacterial cellulose part also plays an important role in the recovery process of chronic wounds. This may be related to the fact that the inflammation process of chronic wounds is longer and there is more pus, and the advantage of natural bacterial cellulose is that it can fully absorb pus. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the composite hydrogel according to an embodiment of the present invention;

[0034] Figure 2 This is a UV-vis test graph of the photothermal hydrogel solution of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 1 of the present invention;

[0035] Figure 3 This is a scanning electron microscope image of the cross section of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 2 of the present invention. Figure 3 i in the figure is a cross-sectional scanning electron micrograph of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel; Figure 3 ii in the figure is the electron micrograph of the photothermal water gel; Figure 3 Figure iii is an electron micrograph of the junction between natural bacterial cellulose and photothermal water gel; Figure 3 Figure iv is an electron microscope image of natural bacterial cellulose;

[0036] Figure 4 This is a mechanical property characterization diagram of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 3 of the present invention; Figure 4 Figure a shows the compression, stretching, and knotted stretching properties of the photothermal water gel in turn; Figure 4 b shows the initial state (origin), horizontal stretch (horizontal stretch) and four-side stretch (four-side stretch) properties of the composite hydrogel; Figure 4 c shows the stretching and twisting properties of the composite hydrogel; Figure 4 d in is the stress-strain curve of the composite hydrogel; Figure 4 Figures eg are the mechanical properties data of the composite hydrogel, such as the maximum strain, maximum deformation and Young's modulus;

[0037] Figure 5This is a graph showing the adhesion performance of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 4 of the present invention; Figure 5 Figure a is a diagram showing the adhesion of the photothermal gel on the surface of tissues such as skin, pig liver, pig fat, and pig muscle. Figure 5 Figure b is the adhesion test data of the photothermal water gel; Figure 5 Figure c is a diagram showing the adhesion of the composite hydrogel on surfaces of different materials: glass, steel, polytetrafluoroethylene (PTFE), and skin.

[0038] Figure 6 This is a characterization diagram of the photothermal performance of the photothermal water gel of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 5 of the present invention; Figure 6 a in the figure is the infrared thermal imaging image of the photothermal gel with different DA concentrations and different irradiation time; Figure 6 b in the figure is the statistical diagram of the maximum temperature data of the photothermal water gel with different DA concentrations and different irradiation time;

[0039] Figure 7 This is a characterization diagram of the photothermal properties of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 5 of the present invention; Figure 7 a in the figure is the infrared thermal imaging image of the composite hydrogel with different DA concentrations at different irradiation times; Figure 7 b is the statistical graph of the maximum temperature data of composite hydrogels containing different DA concentrations irradiated at different times; Figure 7 c is the photothermal performance data of the composite hydrogel with DA concentration in Example 2 at different base plate temperatures; Figure 7 d in the figure is the photothermal performance data of the composite hydrogel with DA concentration in Example 2 under different irradiation intensities; Figure 7 e in the figure is the data graph of laser irradiation cycle experiment;

[0040] Figure 8 Graph showing the biocompatibility and blood compatibility results of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 6 of the present invention; Figure 8 Figure a shows the live-dead cell staining of NIH3T3 cells and HUVEC cells grown on native bacterial cellulose using Calcein-AM / PI. Figure 8 Figure b is the biocompatibility experiment of natural bacterial cellulose and photothermal hydrogels with different concentrations of DA in natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel; Figure 8 Figure c is the blood compatibility experiment of natural bacterial cellulose and photothermal hydrogels with different concentrations of DA in natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel;

[0041] Figure 9 This is a graph showing the results of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 7 of the present invention on acute wounds in SD rats; Figure 9 a in the figure is the acute wound healing diagram of different experimental groups; Figure 9 b is the statistical diagram of relative wound area of ​​each experimental group at different time points;

[0042] Figure 10 The RT-PCR results of inflammatory factor-related genes in the wound surface of SD rats on day 14 of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 7 of the present invention;

[0043] Figure 11 This is a graph showing the results of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel on the chronic wound surface of type I diabetic rats corresponding to Test Example 8 of the present invention; Figure 11 a in the figure is the healing picture of diabetic wounds in different experimental groups; Figure 11 b in the figure is the wound healing trajectory diagram; Figure 11 Figure c is a statistical diagram of the relative wound area of ​​each experimental group at different time points;

[0044] Figure 12 The results of IL-1β expression level of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel in diabetic wounds corresponding to Test Example 8 of the present invention; Figure 12 Figure a shows immunofluorescence images of IL-1β- and CD68-labeled macrophages in diabetic wounds of different experimental groups on days 3 and 7; Figure 12 b in the figure is the percentage of IL-1β-positive macrophages to CD68-positive macrophages; Figure 12 c in the figure is the relative gene expression level of IL-1β in diabetic wounds of different experimental groups on days 3, 7, and 14;

[0045] Figure 13 This is the result of IL-6 expression level of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel in diabetic wounds corresponding to Test Example 8 of the present invention; Figure 13 a in the figure is the immunofluorescence image of IL-6 expression levels in diabetic wounds of different experimental groups on the third day; Figure 13 b in the figure is the relative gene expression level of IL-6 in diabetic wounds of different experimental groups on days 3, 7, and 14;

[0046] Figure 14 This is a picture of pus near the wound of a rat diabetic wound when the wound surface was replaced in the early stage using the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 8 of the present invention;

[0047] Figure 15The results of IL-10 expression level of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel in diabetic wounds corresponding to Test Example 8 of the present invention; Figure 15 a in the figure is the immunofluorescence image of IL-10 expression level in diabetic wounds of different experimental groups on the 3rd day; Figure 15 b in the figure is the IL-10 positive coverage rate of diabetic wounds in different experimental groups;

[0048] Figure 16 CD206 fluorescence immunographs of diabetic wounds of each group of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 8 of the present invention;

[0049] Figure 17 Statistical graphs of H&E staining and granulation thickness of diabetic wounds of each group of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 9 of the present invention; Figure 17 a in the figure is HE staining of diabetic wounds in different experimental groups; Figure 17 b in the figure is the thickness of granulation tissue in diabetic wounds of different experimental groups;

[0050] Figure 18 Graphs showing the results of epidermal growth on diabetic wounds of various groups of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogels corresponding to Test Example 9 of the present invention; Figure 18 a in the figure is the CK14 staining image of diabetic wounds in different experimental groups; Figure 18 b in the figure is the relative expression of KGF in diabetic wound tissues of different experimental groups;

[0051] Figure 19 Masson staining and collagen deposition percentage statistics of each group of diabetic wounds of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 10 of the present invention; Figure 19 a in the figure is the Masson staining image of the diabetic wound in each group; Figure 19 b is the statistical graph of collagen deposition percentage of diabetic wounds in each group;

[0052] Figure 20 Statistical graphs of CD34 immunohistochemical staining and positive coverage of diabetic wounds in each group of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Test Example 10 of the present invention; Figure 20 a in the figure is the CD34 immunohistochemistry image of the diabetic wound in each group; Figure 20 b in the figure is the positive rate of CD34 staining in the same visual field.

[0053] Description of the Figures: The symbols or legends in the figures are specifically described as follows: Symbol: 1 is a composite hydrogel with photothermal effect, 2 is natural bacterial cellulose, and 3 is a photothermal hydrogel. Legend: "Yang" is a photothermal hydrogel; "Yin" is a natural bacterial cellulose; "Tai-Chi" is a natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel; "Control" is 3M Tegaderm TM Film's commercial dressing; "Tai-Chi-NIR" is a natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel irradiated with 808nm near-infrared light; "PC" is the positive control group; and "NC" is the negative control group. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0055] like Figure 1 As shown, the composite hydrogel 1 with photothermal effect includes natural bacterial cellulose 2 and photothermal water gel 3; wherein, the natural bacterial cellulose 2 is located inside the composite hydrogel 1, and the photothermal water gel 3 is evenly distributed on the periphery of the natural bacterial cellulose 2, forming a composite hydrogel with a skin-core structure.

[0056] In the embodiment of the present invention, the photothermal hydrogel 3 is a hydrogel with photothermal function and the photothermal hydrogel 3 uniformly wraps the natural bacterial cellulose 2 .

[0057] Wherein, the thickness of natural bacterial cellulose and photothermal water gel is between 1 and 10 mm, and the thickness of natural bacterial cellulose 2 is required not to collapse after melting due to being too high. Preferably, the thickness of natural bacterial cellulose and photothermal water gel is the same, and is 3 mm. Wherein, the thickness of photothermal water gel is the distance of photothermal water gel along the direction of natural bacterial cellulose; the thickness of natural bacterial cellulose is consistent with the thickness direction of photothermal water gel. For example, the final composite hydrogel is used in the form of sheets or thin blocks, and the composite hydrogel is attached to the area to be healed as a dressing or a carrier for drug release, so that the central area of ​​the surface attached to the area to be healed is natural bacterial cellulose, and is in direct contact with the area to be healed, and the periphery is photothermal water gel.

[0058] In the embodiment of the present invention, the natural bacterial cellulose is in a swelling equilibrium state.

[0059] In an embodiment of the present invention, the photothermal water gel is formed from dopamine and polyvinyl alcohol, with a water content of 87.5-95 wt%. Specifically, polydopamine particles are uniformly dispersed in a polyvinyl alcohol (PVA) solution, which is then freeze-crosslinked. Alternatively, the photothermal water gel is formed from bacterial cellulose and bamboo charcoal. Specifically, bamboo charcoal is dispersed in a bacterial cellulose solution, the natural bacterial cellulose is dissolved, and the resulting bacterial cellulose solution is cross-linked to form regenerated natural bacterial cellulose.

[0060] The polyvinyl alcohol is polyvinyl alcohol 1750±50, with a hydrolysis degree of 99%, and the mass fraction of the polyvinyl alcohol in the photothermal water gel is 5-12.5wt%; the polydopamine is prepared by oxidizing the polydopamine with dopamine hydrochloride under alkaline conditions.

[0061] In an embodiment of the present invention, a method for preparing a composite hydrogel with a photothermal effect is provided. The hydrogel comprises the following components: natural bacterial cellulose, photothermal water gel, and water. The specific preparation process is as follows:

[0062] 1) Place natural bacterial cellulose in deionized water until it reaches swelling equilibrium, cut it into the desired shape, and place it in the center of the bottom of the desired mold for later use. For example, the mold can be a 12-well plate, a 6-well plate, or a disposable plate.

[0063] 2) Dissolve 0-1.5 mmol dopamine hydrochloride in deionized water, adjust the pH to 8.0-8.8 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a uniform polydopamine solution for later use.

[0064] 3) The weighed polyvinyl alcohol powder is added to the polydopamine solution prepared in step 2), stirred in a 90° C. water bath for 2 hours, and then the pH is adjusted to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution.

[0065] 4) The photothermal water gel in step 3) is evenly coated or injected around the natural bacterial cellulose in step 1), and then frozen at -10°C to -80°C for 8 to 12 hours, and then melted to obtain a composite hydrogel.

[0066] When the photothermal water gel is composed of bacterial cellulose, bamboo charcoal and water, the specific preparation process is as follows:

[0067] 1) placing natural bacterial cellulose in deionized water to reach swelling equilibrium, cutting it into a desired shape, and placing it at the center of the bottom of a desired mold for later use;

[0068] 2) Weigh lithium hydroxide, urea, and water in a weight ratio of 4.6:15:80.4 in a beaker and dissolve thoroughly to obtain a bacterial cellulose solvent. Refrigerate at 4°C until ready for use.

[0069] 3) Separately, natural bacterial cellulose is weighed and slurried, dried, and a bacterial cellulose powder is formed; 1.5% of the bacterial cellulose powder and 0.1% of bamboo charcoal are weighed and added to a bacterial cellulose solvent, such as an ice bath, and stirred for 2 hours. The mixture is then placed at -10°C to fully dissolve the bacterial cellulose, thereby obtaining a bacterial cellulose solution;

[0070] 4) Add 72 μL of glutaraldehyde per 100 g of the bacterial cellulose solution in step 3), stir quickly and evenly, then evenly apply it around the natural bacterial cellulose and leave it at room temperature for 24 hours to obtain a composite hydrogel with photothermal effect.

[0071] 5) Soaking the composite hydrogel in step 4) in deionized water to remove excess glutaraldehyde crosslinker for subsequent experiments.

[0072] The specific embodiments are as follows:

[0073] Example 1

[0074] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0075] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0076] 2) Dissolve 0 mmol dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution for later use;

[0077] 3) Weighing 10% (w / w) polyvinyl alcohol powder into the polydopamine solution from step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0078] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0079] Example 2

[0080] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0081] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0082] 2) Dissolve 0.5 mmol dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution, which is set aside.

[0083] 3) Weighing 10% (w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0084] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0085] Example 3

[0086] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0087] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0088] 2) Dissolve 1 mmol of dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution for later use;

[0089] 3) Weighing 10% (w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0090] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0091] Example 4

[0092] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0093] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0094] 2) Dissolve 1.5 mmol of dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution, which is set aside.

[0095] 3) Weighing 10% (w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0096] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0097] Example 5

[0098] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0099] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0100] 2) Dissolve 1.5 mmol of dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution, which is set aside.

[0101] 3) Weighing 5% (w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0102] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0103] Example 6

[0104] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0105] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed in the center of the bottom of a six-well plate mold for later use;

[0106] 2) Dissolve 1.5 mmol of dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution, which is set aside.

[0107] 3) Weighing 7.5% (w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0108] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0109] Example 7

[0110] Natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, specifically as follows:

[0111] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed at the center of the bottom of a six-well plate mold for later use;

[0112] 2) Dissolve 1.5 mmol of dopamine hydrochloride (DA) in deionized water, adjust the pH to 8.5 with 0.1 mol / L NaOH, and stir magnetically at 800 rpm for 30 minutes to obtain a polydopamine solution, which is set aside.

[0113] 3) Weighing 12.5% ​​(w / w) of the polyvinyl alcohol powder into the polydopamine solution of step 2), stirring in a 90° C. water bath for 2 hours, and then adjusting the pH to neutral with 1% HCl (v / v) to obtain a photothermal water gel solution;

[0114] 4) The photothermal hydrogel solution in step 3) is evenly applied around the natural bacterial cellulose in step 1), and placed in a -20°C refrigerator to be frozen overnight. The composite hydrogel with photothermal effect is obtained after thawing the next day.

[0115] The above embodiments 1-7 are only examples. The content parameters of polydopamine can also be adjusted according to actual conditions. In addition to the above examples of 0.095 g / L, 0.190 g / L and 0.285 g / L, in actual experiments, the polydopamine prepared when the concentration of dopamine hydrochloride is ensured to be 0.019 g / L to 0.285 g / L can be used to prepare photothermal water gel, which can achieve photothermal effect and be applied to the composite hydrogel of the present invention, and realize the corresponding technology.

[0116] Example 8

[0117] Natural bacterial cellulose-bacterial cellulose / bamboo charcoal composite hydrogel, specifically as follows:

[0118] 1) After the natural bacterial cellulose is allowed to swell to equilibrium, it is cut into the desired shape and placed in the center of the bottom of a six-well plate mold for later use;

[0119] 2) Weigh lithium hydroxide, urea, and water in a weight ratio of 4.6:15:80.4 in a beaker and dissolve thoroughly to obtain a bacterial cellulose solvent. Refrigerate at 4°C until ready for use.

[0120] 3) Weighing 1.5% of the bacterial cellulose powder from step 1) and 0.1% of bamboo charcoal into a bacterial cellulose solvent, stirring on ice for 2 hours, and then placing at -10°C to fully dissolve the bacterial cellulose, thereby obtaining a bacterial cellulose solution;

[0121] 4) Add 72 μL of glutaraldehyde per 100 g of the bacterial cellulose solution in step 3), stir quickly and evenly, then evenly apply it around the natural bacterial cellulose and leave it at room temperature for 24 hours to obtain a hydrogel with a photothermal effect;

[0122] 5) Soaking the hydrogel in step 4) in deionized water to remove excess glutaraldehyde crosslinker for subsequent experiments.

[0123] The above-mentioned Example 8 is merely an example, and the bamboo charcoal content parameters can be adjusted according to actual conditions. In actual experiments, ensuring that the bamboo charcoal addition amount is based on the existing technology, for example, the mass volume ratio of bacterial cellulose to water is 15g / L to 30g / L, and the mass volume ratio of bamboo charcoal to water is 0.5g / L to 1g / L, can prepare composite hydrogels with photothermal effect, achieve photothermal effect, and be applied to the composite hydrogel of the present invention, and realize the corresponding technology.

[0124] The composite hydrogels of the present invention were prepared by adjusting the ratios of the various raw materials using the above method. For the composite hydrogels in Examples 1-8, natural bacterial cellulose was cut into circular pieces with a diameter of 1.4 cm and placed at the center of the bottom of the same six-well plate mold. The thickness of both the natural bacterial cellulose and the photothermal hydrogel was controlled to be 3 mm.

[0125] The following are test examples of the above embodiments, specifically:

[0126] Test Example 1, UV-vis test experiment of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel based on Examples 1-4, specifically as follows:

[0127] Based on the successful oxidation polymerization of DA into PVA solution in Examples 1-4, a precursor solution for photothermal hydrogel formation was formed. The photothermal hydrogel solutions with different DA contents were diluted 4 times and their absorption peaks were tested by UV-vis. Figure 2The photothermal hydrogel precursor solution exhibits a distinct absorption peak at 320 nm with the addition of DA, which increases with increasing DA concentration. This peak represents a π-π* transition of aromatic hydrocarbons containing a benzene ring structure, demonstrating the successful oxidative polymerization of DA in the photothermal hydrogel precursor solution.

[0128] Test Example 2, based on the scanning electron microscopy test of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel of Example 2, wherein the details are as follows:

[0129] The hydrogel in Example 2 was freeze-dried, and then the cross-section of the hydrogel was tested by field emission scanning microscopy. Figure 3 The results show that after freeze-crosslinking, there is a clear boundary line between the photothermal hydrogel part and the natural bacterial cellulose. Part of the network of the photothermal hydrogel at the junction penetrates into the network structure of the natural bacterial cellulose, while there is no network structure of the photothermal hydrogel in the natural bacterial cellulose at the far end. Therefore, it is shown that the composite hydrogel of the present invention well maintains the three-dimensional spatial structure of natural bacterial cellulose and maintains the natural structure of bacterial cellulose.

[0130] Test Example 3, based on the mechanical properties experiments of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel, photothermal water gel and natural bacterial cellulose corresponding to Examples 1-4, is as follows:

[0131] The composite hydrogels in Examples 1-4 were deformed to different degrees. Figure 4 As shown in a, the photothermal hydrogel exhibits good compression, stretching, and knotting properties. Subsequently, we subjected the composite hydrogel to different degrees of deformation, such as Figure 4 As shown in Figures b and c, the composite hydrogel can be stretched horizontally, stretched on four sides, and twisted well. In the stretching process, the photothermal hydrogel part is stretched longer than the natural bacterial cellulose part, and has better deformation and elasticity. Figure 4 The dg in the figure represents mechanical properties testing, conducted at 50% relative humidity and a tensile rate of 30 mm / min. The results show that the elongation at break of the photothermal hydrogels is above 200%, with a Young's modulus ranging from 23.88±2.20 kPa to 29.00±3.68 kPa. In contrast, the elongation at break of natural bacterial cellulose is only 27.93±5.27%, with a Young's modulus of 5.54±1.68 MPa. These results demonstrate the difference in mechanical properties between the inner and outer components of the composite hydrogels of the present invention: natural bacterial cellulose exhibits high strength but poor stretchability, while the photothermal hydrogels exhibit greater stretchability but lower strength. The high stretchability of the photothermal hydrogels allows them to better adapt to the process of skin stretching.

[0132] Test Example 4, based on the adhesion performance experiment of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Examples 1-4, is as follows:

[0133] The photothermal gels in Examples 1-4 were tested for their adhesion properties on several tissue surfaces, including skin, pig liver, pig fat, and pig muscle. Figure 5 As shown in b, the adhesion strength of the photothermal gel increases with the increase of DA concentration, indicating that DA can improve the viscosity of the photothermal gel. Figure 5 As can be seen from c in the figure, the composite hydrogel can adhere to different materials, including glass, steel, polytetrafluoroethylene (PTFE) and skin. The above shows that the incorporation and oxidative polymerization of DA can provide adhesion to the composite hydrogel of the present invention, and it has the potential to be used as a wound dressing.

[0134] Test Example 5, based on the photothermal performance experiment of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Examples 1-4, is as follows:

[0135] A constant temperature plate was used to simulate the human skin temperature (32°C), and the radiation conditions were 808 nm laser (near-infrared, NIR) with an irradiation intensity of 1 W / cm -2 The irradiation time was 30 minutes, and the temperature was tested every 5 minutes using an infrared temperature gun. Figure 6 As shown in the figure, the addition of DA can increase the temperature of the photothermal hydrogel, and the temperature increases with the increase of DA concentration, and the highest temperature is concentrated in the middle part. After 10 minutes, the temperature is too high, causing the water in the hydrogel to evaporate, resulting in the subsequent temperature continuing to rise and the temperature is not stable enough. Under the same experimental conditions, Figure 7 As shown in a, the composite hydrogel can reduce the temperature of the peripheral photothermal hydrogel because natural bacterial cellulose does not have photothermal properties, thereby improving the temperature stability of the hydrogel within 20 minutes. Moreover, when used as a wound dressing, it can directly contact the wound to prevent local overheating and damage to the wound. Figure 7 Figure b is the statistical value of the highest temperature of the composite hydrogels containing different DA concentrations. It can be seen that the 0.5 mmol composite hydrogel has strong stability under NIR irradiation, reaching 41.13±0.31°C after 5 minutes of irradiation, and the temperature is 41.17±0.23°C after 20 minutes. The temperature is the most stable and the temperature range is appropriate, which meets the requirements of the next experiment.

[0136] Since the temperature of the skin in different parts is different, we simulated the surface temperature of the skin in different parts through a constant temperature plate. The skin temperature of rats is higher than that of humans. The average skin temperature of rats tested by infrared detectors is around 34°C. Therefore, we selected 32°C, 34°C and 37°C to test the changes in the photothermal effect. The results are as follows Figure 7 As shown in Figure c, the photothermal conversion capacity is related to the bottom skin temperature. The higher the bottom temperature, the higher the temperature of the hydrogel. In order to achieve the most suitable temperature for animal experiments (40-41°C), we fixed the constant temperature of the thermostat at 34°C and adjusted the irradiation intensity to 0.8, 0.9 and 1 W / cm -2 , the results are as follows Figure 7 As shown in d, 0.9W / cm -2 The temperature was the most suitable, so the subsequent animal experiments selected 0.5mmol composite hydrogel and 0.9W / cm -2 , 20 minutes. In addition, in order to test the thermal stability of the composite hydrogel, we conducted three "on-off" laser irradiation cycle experiments on the photothermal stability of 0.5mmol composite hydrogel, such as Figure 7 As shown in Figure e, the composite hydrogel exhibits very good thermal stability.

[0137] Verify that the dopamine hydrochloride in Examples 1-4 is oxidatively polymerized into PVA to prepare a wound dressing with photothermal properties, and solve the problem of improving the temperature stability of the composite hydrogel and solving the problem of possible overheating in the central part.

[0138] Test Example 6, based on the biocompatibility and blood compatibility experiments of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Examples 1-4, is as follows:

[0139] Cell stability experiments were conducted on the natural bacterial cellulose part and the photothermal hydrogel part of the hydrogel of the present invention. NIH3T3 and HUVEC cells were used to simulate fibroblasts and vascular cells respectively. Since the natural bacterial cellulose is in direct contact with the wound surface, the live and dead cells on the surface of the natural bacterial cellulose were detected by the Calcein-AM / PI double staining method. Calcein-AM stains live cells, and the cells appear green. PI stains dead cells, and the cells appear red. Figure 8 As shown in a, NIH3T3 cells and HUVEC cells were inoculated on natural bacterial cellulose for 1 day, and the cells adhered to and grew on the natural bacterial cellulose. After 3 days of culture, both cell types continued to grow, and there were not many dead cells, indicating that direct contact has a good effect on cell survival.

[0140] In order to further verify the effects of natural bacterial cellulose and photothermal hydrogel on cell activity, the effects of photothermal hydrogel and natural bacterial cellulose extracts containing different DA concentrations on cells were tested by CCK-8. Figure 8 Figure b shows that compared with the PC group, the cell viability of each group was above 80% on the first and third days, indicating that the biocompatibility of the composite hydrogel of the present invention is very good. In addition, the blood compatibility of the natural bacterial cellulose and photothermal hydrogel parts of the hydrogel of the present invention was evaluated. Figure 8 Figure c shows that the hemolysis rate of each group is below 5%, indicating that the composite hydrogel has good blood compatibility. In summary, the present invention has good biosafety and can be used for the next in vivo experiment.

[0141] Test Example 7, based on the acute full-thickness cortical injury experiment of natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel of Examples 1-4, is as follows:

[0142] The experiment was conducted on an acute full-thickness cortical injury model of SD (Sprague Dawley) rats. After adaptive feeding, the rats were anesthetized by intraperitoneal injection of 1% sodium pentobarbital (30 mg / kg), hair was removed, and a full-thickness cortical injury with a diameter of 1 cm was made. The experiment was divided into three groups: the control group was 3MTegaderm TM Film was a commercial dressing. Tai-Chi was a natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel. Tai-Chi-NIR was a natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel combined with 808nm near-infrared light irradiation. The Tai-Chi-NIR group was irradiated for 20 minutes daily from day 1 to day 5. Images were taken on days 3, 7, 10, and 14, and samples were collected on days 7 and 14.

[0143] from Figure 9 As can be seen from a, compared with the other two groups, the wound healing speed of the Tai-Chi-NIR group was significantly improved, and the wound was completely closed on the tenth day. Figure 9 The statistical data of the relative area of ​​the wound can be seen in b. The wound of the Tai-Chi-NIR group is significantly smaller than that of the Control group and the Tai-Chi group, while there is no significant difference between the Tai-Chi group and the Control group. This shows that in the healing process of acute wounds, the level of wound healing of the Tai-Chi hydrogel alone is not much different from that of commercial dressings. Its effect of accelerating wound healing is mainly due to its photothermal properties, indicating that the warm effect promotes the repair of acute wounds. Next, we used RT-PCR technology to detect inflammatory factors in the new tissue of the wound on the 14th day. Figure 10It can be seen that Tai-Chi hydrogel alone can significantly downregulate the levels of proinflammatory factors IL-6 and TNF-α and increase the level of anti-inflammatory factor IL-10, while Tai-Chi hydrogel synergistically with NIR stimulation can significantly downregulate the level of proinflammatory factor IL-1β and further increase the level of proinflammatory factor IL-10. Moreover, the effect on IL-1β is only related to the photothermal effect and has little to do with the Tai-Chi hydrogel itself, while the effect on IL-6 levels is only related to the Tai-Chi hydrogel itself and has little to do with the photothermal effect. This suggests that Yin affects IL-6 and IL-10, and photothermal effects IL-1β and IL-10. This result suggests that Tai-Chi hydrogel may be more suitable as a dressing for chronic wounds.

[0144] Test Example 8, based on the diabetic chronic full-thickness cortical injury experiment of the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel of Examples 1-4, is as follows:

[0145] The experiment involved a Sprague Dawley (SD) rat model with chronic full-thickness diabetic cortical injury. After adaptive feeding, the rats were fasted with water for 12-18 hours beforehand. Then, they were intraperitoneally injected with 60 mg / kg of streptozotocin (STZ). Within one week after injection, blood glucose levels were randomly tested. A successful type 1 diabetes model was considered successful if blood glucose levels exceeded 16.7 mmol / L on three occasions. The remaining experimental procedures were consistent with those in Test Example 7, with samples collected on days 3, 7, and 14.

[0146] Depend on Figure 11 As can be seen from a in the figure, unlike acute wounds, the effect is most obvious on the third day in the early stage of wound healing. Compared with the Control group, the Tai-Chi hydrogel alone has the effect of promoting wound healing, and the Tai-Chi-NIR group with synergistic NIR stimulation has a further promoting effect. Figure 11 b in the figure is the wound healing trajectory diagram of a. Figure 11 Figure c shows the statistical results. During the entire healing process, there were significant differences among the Tai-Chi group, Tai-Chi-NIR group, and Control group. The significant differences between the Tai-Chi-NIR and Tai-Chi groups were mainly on the 3rd and 7th days, and there was little effect at later time points.

[0147] Simple composite hydrogel and composite hydrogel combined with NIR therapy can change the inflammatory microenvironment of diabetic wounds, as follows:

[0148] The above experiments show that the effect of Tai-Chi hydrogel on diabetic wounds is mainly on the 3rd and 7th days, especially on the 3rd day. This period is mainly the inflammatory stage of the wound. Figure 12Figure a is the co-staining image of IL-1β and CD68 (macrophage marker), and figure b is the percentage of IL-1β and CD68 fluorescence intensity on the third day of figure a. It can be seen that the downregulation of IL-1β level is mainly affected by NIR, and Figure 12 The RT-PCR results of the whole process in c showed the same results. Compared with the Control group and Tai-Chi group, the IL-1β level in the Tai-Chi-NIR group was downregulated, which suggested that the photothermal hydrogel of Tai-Chi hydrogel mainly affected IL-1β. Figure 13 Figure a shows that on the third day, the IL-6 positive rates in the Tai-Chi group and the Tai-Chi-NIR group were lower than those in the Control group, while there was little difference between the Tai-Chi group and the Tai-Chi-NIR group. Figure 13 The gene expression results of b in showed the same results. Figure 14 The results showed that in the first few days of the wound healing cycle, when we changed the dressing, the wounds of the Tai-Chi and Tai-Chi-NIR groups were dry, while the control group accumulated a large amount of pus. IL-6 is an indicator related to sepsis. This suggests that the pus adsorption function of the Yin hydrogel of Tai-Chi hydrogel is an important reason for the downregulation of its IL-6 index. In addition, we also detected the changes in the level of the anti-inflammatory factor IL-10. Figure 15 Figure a shows that on the third day, the level of IL-10 was highest in the Tai-Chi-NIR group, followed by the Tai-Chi group, and the lowest in the Control group. Figure 15 The b shows Figure 15 The positive rate of IL-10 in the Tai-Chi-NIR group was significantly higher than that in the other two groups. These results confirmed the hypothesis of Test Example 7 that Tai-Chi hydrogel has the effect of regulating the wound microenvironment. This beneficial effect is more obvious in chronic wounds with longer inflammatory periods. In addition, Figure 16 As shown, we marked the wound tissue with CD206 (a marker of M2 macrophages). It can be seen that the CD206 level in the Tai-Chi-NIR group on the third day was significantly higher than that in the other two groups, and the Tai-Chi group was also higher than the Control group. This indicates that in diabetic wounds, Tai-Chi hydrogel can promote the transformation of macrophages to M2 type, and this effect can be greatly enhanced under the stimulation of NIR, promoting the wound to enter the proliferation phase.

[0149] Test Example 9, based on the experiment of promoting granulation and epidermal formation on diabetic wounds using the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Examples 1-4, is as follows:

[0150] To further explore the effect of Tai-Chi hydrogel on the formation of granulation tissue and epidermal tissue in diabetic wounds of rats, the wound tissue was characterized by H&E staining and CK14 (Cytokeratin 14, a keratinocyte marker) immunohistochemical staining. Figure 17 As can be seen in a, the new tissue generation in the Tai-Chi-NIR group is faster than that in the other two groups. On the 14th day, mature hair follicles (red arrows) and glands (yellow arrows) have been formed. On the 3rd day, it can also be seen that the granulation tissue grows faster than that in the other two groups. Figure 17 As can be seen in Figure b, on the third day, the thickness of granulation tissue in the Tai-Chi-NIR group was significantly higher than that in the Tai-Chi group and the Control group, and that in the Tai-Chi group was also significantly higher than that in the Control group. Figure 18 It can also be seen in a that the level of CK14 in the Tai-Chi-NIR group (blue arrow) was significantly higher than that in the other two groups, and a complete epidermal layer was formed on the 7th day. Figure 18 Figure b is the RT-PCR result of KGF (Keratinocyte growth factor). We can see the same results. On the third day, the KGF expression level in the Tai-Chi-NIR group was significantly higher than that in the other two groups. Figure 17 and Figure 18 The results showed that compared with the control, the Tai-Chi hydrogel alone also promoted epidermal growth.

[0151] Test Example 10, based on the experiment of promoting collagen and angiogenesis in diabetic wounds using the natural bacterial cellulose-polyvinyl alcohol / polydopamine composite hydrogel corresponding to Examples 1-4, is as follows:

[0152] Collagen production and angiogenesis are important indicators for evaluating wound repair. In order to further explore the effects of Tai-Chi hydrogel on collagen production and angiogenesis in diabetic wounds of rats, Masson staining and CD34 (vascular endothelial cell marker) immunohistochemical staining of wound tissue were performed to characterize the wound tissue. Figure 19 As shown in a, the collagen production in the Tai-Chi-NIR group was faster than that in the other two groups. On the 14th day, the collagen deposition effect of the wound surface in this group was not much different from that of the surrounding normal tissues. Figure 19 The statistical data of b also show that the amount of collagen deposition in the Tai-Chi-NIR group was significantly higher than that in the other two groups on days 3, 7, and 14. Blood vessels provide nutrition for wound formation. Figure 20CD34 in a shows the generation of vascular endothelial cells in the wound tissue. It can be seen that as the wound healing process progresses, in the middle and late stages, the blood vessels (purple arrows) gradually disappear and their diameters gradually decrease. On the 7th and 14th days, the blood vessel diameters in the Tai-Chi-NIR group were significantly smaller than those in the other two groups. Figure 20 Statistics also show that in the early stages of wound healing, the Tai-Chi-NIR group had a significantly higher proportion of blood vessels than the other two groups, providing nutrients for wound repair. As wound healing accelerated, the amount of blood vessels in this group decreased significantly on day 14, indicating a faster wound repair process. These results demonstrate that the Tai-Chi hydrogel of the present invention can promote wound repair, and that synergistic NIR stimulation significantly increases angiogenesis and collagen deposition, demonstrating that the hydrogel's photothermal effect plays a significant role.

[0153] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite hydrogel with photothermal effect, characterized in that: The composite hydrogel is a skin-core structure, comprising natural bacterial cellulose and photothermal water gel; wherein the natural bacterial cellulose is the core layer, and the photothermal water gel is the skin layer.

2. The composite hydrogel with photothermal effect according to claim 1, characterized in that: The natural bacterial cellulose is in a swelling equilibrium state.

3. The composite hydrogel with photothermal effect according to claim 1, characterized in that The thickness of the natural bacterial cellulose and the photothermal water gel is 1 to 10 mm.

4. The composite hydrogel with photothermal effect according to claim 3, characterized in that: The thickness of the natural bacterial cellulose and the photothermal water gel is 3 mm.

5. The composite hydrogel with photothermal effect according to claim 1, characterized in that: The photothermal water gel comprises polydopamine, polyvinyl alcohol and water; wherein the water content of the photothermal water gel is 87.5 to 95 wt %; the mass fraction of the polyvinyl alcohol in the photothermal water gel is 5 to 12.5 wt %; and the polydopamine is prepared by oxidizing dopamine hydrochloride under alkaline conditions.

6. The composite hydrogel with photothermal effect according to claim 1, characterized in that The photothermal water gel comprises bacterial cellulose, bamboo charcoal and water, wherein the mass volume ratio of the bacterial cellulose to water is 15 g / L to 30 g / L, and the mass volume ratio of the bamboo charcoal to water is 0.5 g / L to 1 g / L.

7. The method for preparing a composite hydrogel with photothermal effect according to any one of claims 1 to 5, characterized in that: The steps include: S11: placing natural bacterial cellulose in deionized water to reach swelling equilibrium, cutting it into a predetermined shape, and placing it at the center of the bottom of the mold; S12: Weighing dopamine hydrochloride and dissolving it in deionized water, adjusting the pH to 8.0-8.8, to obtain a polydopamine solution; weighing polyvinyl alcohol powder and adding it to the polydopamine solution, mixing them evenly, and adjusting the pH to neutral, to obtain a photothermal water gel solution; S13: evenly distributing the photothermal water gel solution around the natural bacterial cellulose in the mold in step S11, freezing it at -10 to -80°C for 8 to 12 hours, and then thawing it to obtain a composite hydrogel.

8. The method for preparing a composite hydrogel with photothermal effect according to claim 7, characterized in that: The concentration of the dopamine hydrochloride is 0.019 g / L to 0.285 g / L.

9. The method for preparing a composite hydrogel having a photothermal effect according to any one of claims 1 to 4 and 6, wherein: The steps include: S21: placing natural bacterial cellulose in deionized water to reach swelling equilibrium, cutting it into a predetermined shape, and placing it at the center of the bottom of the mold; S22: Weighing lithium hydroxide: urea: deionized water in a weight ratio of 4.6:15:80.4 and fully dissolving them to obtain a bacterial cellulose solvent; weighing bacterial cellulose to form a homogenate, and drying to form a bacterial cellulose powder; dissolving the bacterial cellulose powder and bamboo charcoal in the solvent, mixing them in an ice bath, and then fully dissolving them at -10°C to obtain a photothermal water gel solution; S23: adding glutaraldehyde to the photothermal water gel solution, mixing evenly, and then evenly arranging the solution around the natural bacterial cellulose in the mold in step S11, and leaving the solution at room temperature to prepare a composite hydrogel.

10. Use of the composite hydrogel with photothermal effect according to any one of claims 1 to 6 for preparing wound dressing or drug release carrier.

Images