3D-printed self-power-generating hydrogel scaffold and preparation method and application thereof

Abstract

The present application relates to the technical field of biomedical materials, and particularly relates to a 3D-printed self-produced electricity hydrogel scaffold for promoting wound healing and a preparation method and application thereof, comprising an anode scaffold and a cathode scaffold, the anode scaffold is prepared from a zinc-containing hydrogel, and the cathode scaffold is prepared from an iron-containing hydrogel; the anode scaffold further comprises a prepolymerization solution prepared from dopamine, ammonium persulfate, N,N'-methylene bisacrylamide, acrylamide and tetramethylethylenediamine; the hydrogel scaffold can gradually degrade to release metal ions, play an anti-inflammatory and angiogenic role, can remove free radicals such as active oxygen and active nitrogen, and play an antioxidant role; the output voltage can be stabilized for more than 7 days, the expression of repair-related genes can be improved through physiological micro-current stimulation, the proliferation and migration of fibroblasts can be promoted, the wound can be accelerated to realize scarless healing within 16 days, and the hydrogel scaffold has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomedical engineering, and particularly relates to a 3D-printed self-power-generating hydrogel scaffold and a preparation method and application thereof. BACKGROUND

[0002] Due to persistent infection, inflammatory infiltration, insufficient vascularization and oxidative damage, skin injury usually shows delayed healing and is prone to form scars. Good wound healing depends on the comprehensive management of the inflammatory, repair and remodeling stages. Traditional dressings mainly target specific stages of the healing process and rely on biological agents such as antibiotics and growth factors, but often face problems in promoting wound healing, including drug resistance and potential tumorigenicity. Recent studies have shown that methods using physical stimuli (electricity, magnetism and light) and chemical signals (ions) can effectively regulate the microenvironment of tissue healing, showing the prospect of accelerating wound healing and achieving scarless results.

[0003] Electrical stimulation, as a basic attribute of biological activity, can dynamically regulate the TGF-β / Smad signaling pathway, thereby promoting cell proliferation, migration and extracellular matrix remodeling, while inhibiting scar formation. However, biological electricity usually gradually weakens during the physiological healing process, leading to down-regulation of genes involved in repair and healing, resulting in disordered collagen fiber deposition and abnormal remodeling of extracellular matrix. Therefore, the development of new wound dressings that can simulate and enhance endogenous bioelectricity is crucial for accelerating healing and preventing scar formation. Implantable piezoelectric materials provide a method for endogenous electrical stimulation. However, these bioelectric signals usually require force-to-electricity conversion, resulting in unstable and unsustainable signal output. In contrast, biodegradable batteries have attracted widespread attention due to their current stability, high energy density and ease of use. Enzyme cascade-based biofuel cells (EBFCs) have shown potential for stable current output and scarless wound healing, but they face many challenges, including sensitivity to environmental factors (such as temperature and pH), loss of activity and high cost, which ultimately hinder their large-scale customization and clinical application.

[0004] Unlike previous self-powered strategies, metal materials such as magnesium, zinc, molybdenum, iron, and tungsten have increasingly become electrode materials due to their inherent electrochemical potential difference. Existing research has developed biodegradable batteries based on magnesium anodes, however, due to their very low standard electrode potential (-2.38 V vs. standard hydrogen electrode), their oxidation-reduction reactions are often intense, limiting the working time of the battery, and in practical applications, the dressing often needs to be replaced frequently. In contrast, zinc as a promising anode material has increasingly attracted the attention of researchers in recent years. Zinc can exhibit a more moderate and stable reaction (its standard electrode potential is -0.76 V vs. standard hydrogen electrode), which can provide more sustained current to promote wound healing. In addition, the Zn2+ released during the degradation of zinc exhibits significant broad-spectrum antibacterial effect and inherent anti-inflammatory ability by inhibiting the NF-κB signaling pathway, thereby assisting the smooth transition from the inflammation stage to the repair stage of wound healing, preventing the development of chronic wounds. Subsequently, when wound healing enters the repair stage, insufficient angiogenesis can also lead to delayed and scarred healing. Iron as a common cathode material can form a potential difference with zinc, and the release of iron ions during degradation can promote angiogenesis through the HIF-1a / VEGF signaling pathway, thereby accelerating the healing of the wound repair stage. Therefore, a zinc-iron bio-battery can take advantage of the combined advantages of enhanced endogenous electrical stimulation, antibacterial and anti-inflammatory properties, and promotion of angiogenesis, thereby providing sufficient physical stimulation and chemical signals to the damaged area, providing a solution to accelerate scar-free wound healing.

[0005] However, there are several challenges in using metal to construct electrode systems in wound dressings: (1) unable to provide a suitable living environment for cells in the defect site; (2) slow degradation in vivo and easy to produce large-scale metal ion precipitation, which has an adverse effect on the wound site; (3) complex manufacturing process, which requires a separator between the anode and cathode to prevent short circuits. Therefore, there are relatively few reports on metal-based bio-battery-type self-powered wound dressings. To address these challenges, hydrogels can provide a moist environment conducive to cell survival, degradability, and more notably, hydrogels have both solid and liquid properties, the solid properties enable them to function like a separator, and the liquid properties enable them to act as electrolytes and promote ion transport. Therefore, the degradable electrode system formed by hydrogels and metal powders can provide an excellent living and inducing environment for the wound site. However, traditional hydrogel battery production techniques usually involve separately manufacturing two electrode materials and then assembling them together, which limits strong bonding, structural stability, and large-scale replicability.

[0006] 3D printing technology provides advantages such as rapid manufacturing, personalization, and multi-material integration, providing an excellent strategy for one-step preparation of battery hydrogels. Among various hydrogels, sodium alginate (SA) stands out due to its unique printability and can be combined with Ca2 + Crosslinking to form calcium alginate solid electrolyte, not only can promote the ion transport inside the battery, but also can provide a favorable environment for cell survival. At the same time, gelatin (AG) as the denatured hydrolysate of collagen, exhibits excellent biocompatibility, degradability and cell adhesion sites, thus providing an optimal environment for cell survival, while enhancing the mechanical properties of SA and regulating its degradability. Therefore, the design of a double bio-ink combined with zinc and iron powder and SA / AG (SG) hydrogel, and the layer-by-layer stacking of cathode and anode by double-nozzle 3D printing provides a promising method for the construction of battery hydrogel.

[0007] In addition, the detachment of the dressing during use will also cause the interruption of the physical electric stimulation and chemical ionic signals applied. The gold standard for dressing fixation in clinic often adopts suture fixation, which not only increases the trauma, but also makes the suture site more prone to scar formation. Therefore, the adhesion of the new dressing has attracted widespread attention. Polydopamine (PDA) has a similar structure to the adhesive protein of mussels, has excellent adhesion, conductivity and cell affinity, and can promote the transmission of electric stimulation through the dressing to the skin defect site. However, there are difficulties in constructing a printable adhesive hydrogel based on PDA: the carboxyl groups of SA can combine with the amino and phenolic hydroxyl groups of PDA, thereby "blocking" certain adhesion sites of polydopamine. In addition, the contact area of the printed hydrogel with the tissue will be reduced, and these factors will reduce its overall adhesion, therefore, it is a better choice to construct a pre-polymerization solution to form an adhesive layer in situ on the surface of the scaffold.

[0008] In summary, the present application provides a 3D-printed self-powering hydrogel scaffold for promoting wound healing, which integrates multiple modules such as simulating endogenous electric field, antibacterial, anti-inflammatory, angiogenic, free radical scavenging and adhesion performance, which can accelerate the scarless healing of wounds within 16 days, which is superior to the silicone-based wound dressings on the market, which represents a pioneering achievement in accelerating scarless healing of wounds through metal-based primary battery hydrogel, and provides a revolutionary solution for repairing damaged tissues based on metal-based primary battery hydrogel to provide physical and chemical signals. SUMMARY

[0009] The purpose of the present application is to provide a 3D-printed self-powering hydrogel scaffold, which comprises an anode scaffold and a cathode scaffold, the anode scaffold is a zinc-containing hydrogel obtained by 3D printing, and the cathode scaffold is an iron-containing hydrogel obtained by 3D printing.

[0010] Preferably, the concentration of zinc and iron in the hydrogel is 0.5% to 1% w / v.

[0011] Preferably, the hydrogel is prepared by adding gelatin to deionized water and then adding sodium alginate.

[0012] Preferably, the outer part of the anode support is also wrapped with a prepolymerization solution prepared from dopamine, ammonium persulfate, N,N'-methylene bisacrylamide, acrylamide and tetramethyl ethylenediamine.

[0013] Preferably, in the prepolymerization solution, the ratio of dopamine to acrylamide is 0.2-1.2% w / t; the ratio of ammonium persulfate to acrylamide is 10% w / t; the ratio of N,N'-methylene bisacrylamide to acrylamide is 0.12% w / t; and the volume ratio of tetramethyl ethylenediamine to water solvent is 1:625.

[0014] The second object of the present application is to provide a preparation method of the self-power-generating hydrogel support, comprising the following steps: (1) dissolving gelatin in deionized water and adding sodium alginate, stirring uniformly;

[0015] (2) dividing the solution obtained in step (1) into two parts, respectively adding zinc powder and iron powder, stirring uniformly to obtain anode support material and cathode support material;

[0016] (3) loading the anode support material and the cathode support material obtained in step (2) into a 3D printing cartridge, using a double-nozzle 3D printing technology for printing, soaking in a calcium chloride solution, and storing overnight to obtain an anode support and a cathode support;

[0017] (4) dissolving dopamine in an alkaline aqueous solution and stirring until the solution turns brown;

[0018] (5) under ice bath, adding ammonium persulfate, N,N'-methylene bisacrylamide, acrylamide and tetramethyl ethylenediamine to the solution obtained in step (4) in sequence to form a brown prepolymerization solution;

[0019] (6) pouring the solution obtained in step (5) into a mold, soaking one end of the anode support obtained in step (3) in the mold, and placing it in a 60℃ oven for 30min to form a ZFBH support with adhesion.

[0020] Preferably, the reaction in step (1) is carried out under heating conditions, and the mass / volume ratio of zinc powder or iron powder to deionized water in step (2) is 0.5%-1% (w / v); the concentration of the calcium chloride solution in step (3) is 2% (w / v).

[0021] Preferably, the pH value of the alkaline aqueous solution in step (4) is 12.

[0022] The third object of the present application is to provide the self-power-generating hydrogel support or the self-power-generating hydrogel support prepared by the preparation method in the preparation of skin repair materials and tissue engineering.

[0023] A fourth object of the present application is to provide the use of the self-power-generating hydrogel scaffold or the self-power-generating hydrogel scaffold prepared by the preparation method in the preparation of a dressing for treating skin injury.

[0024] The present application has the following beneficial effects: (1) The present application uses direct writing 3D printing technology to prepare a self-power-generating hydrogel scaffold, which has excellent biocompatibility, stable and long-lasting voltage output, and exhibits excellent effects of promoting scar-free healing of wounds; provides a suitable living environment and an induction environment for cells in the wound healing site, simulates and amplifies endogenous electrical stimulation, cascade regulates the expression of wound site repair-related genes, and reduces the expression of pro-inflammatory factors and accelerates the vascularization of the wound site, thereby promoting the scar-free healing of the wound.

[0025] (2) The self-power-generating hydrogel scaffold prepared by the present application has both solid and liquid properties, which plays a role similar to a battery separator based on the solid property, and acts as an electrolyte based on the liquid property, and promotes ion transmission, thereby effectively solving the problem of complex structure of traditional batteries due to the need to build a separator.

[0026] (3) The self-power-generating hydrogel scaffold prepared by the present application has multiple repair mechanisms such as physical stimulation and chemical stimulation, including the release of zinc ions to play an anti-inflammatory role, the release of iron ions to play a role in promoting vascularization, the excellent antioxidant performance of each component unit, the continuous generation of bioelectricity to promote tissue remodeling, and the realization of scar-free healing of wounds, thereby effectively avoiding the shortcomings of traditional dressings such as single action and low effect.

[0027] (4) The self-power-generating hydrogel scaffold prepared by the present application has a layer of adhesion layer at one end near the wound, which avoids the falling off of the dressing during use, thereby playing a long-lasting bioelectric stimulation.

[0028] (5) The self-power-generating hydrogel scaffold prepared by the present application is based on the method of 3D printing additive manufacturing, which is easy to quickly, batch, scale, and personalize, and has a broad market prospect in the field of skin tissue repair, thereby providing a new treatment scheme for accelerating the scar-free healing of wounds. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be described in further detail below with reference to the accompanying drawings.

[0030] Figure 1 The physical map of the ZFBH scaffold of the present application

[0031] Figure 2 The gelation and adhesion performance characterization of the PDM hydrogel of the present application

[0032] Note: (A) Gelation property; (B) Adhesion mechanics; (C) Adhesion physical map

[0033] Figure 3 Figure legends for the characterization of the microstructure of the ZFBH scaffold and (A) SEM of FeH scaffold at low magnification; (B) SEM of ZnH scaffold at low magnification; (C-D) Element distribution of FeH scaffold and ZnH scaffold; (E-F) SEM of FeH scaffold and ZnH scaffold at high magnification; (G-H) XRD characterization of FeH scaffold and ZnH scaffold; (I) SEM of ZFBH scaffold; (J-K) Element distribution of ZFBH scaffold; (L) XRD characterization of ZFBH scaffold

[0034] Figure 4 Figure legends for the characterization of the performance of the ZFBH scaffold

[0035] Note: (A) Electrical properties; (B) Free radical scavenging performance

[0036] Figure 5 Figure legends for the biocompatibility and cell migration ability test of the ZFBH scaffold

[0037] Note: (A) CCK-8; (B) Live / dead cell staining; (C) Hemolysis experiment; (D) Scratch test

[0038] Figure 6 Figure legends for the mechanism of the ZFBH scaffold for promoting wound healing in vitro

[0039] Note: (A) Antimicrobial performance evaluation; (B) RT-qPCR evaluation of the expression of repair, inflammation and angiogenesis-related genes

[0040] Figure 7 Figure legends for the ZFBH scaffold accelerating scarless healing pictures and H&E, Masson, COL-I, COL-III section pictures. Note: (A) Wound healing photo; (B) Wound area quantification; (C) H&E and Masson staining; (D) Collagen quantification; (E) COL-I and COL-III staining pictures; (F) Quantitative analysis of COL-I and COL-III

[0041] Figure 8 Figure legends for the ZFBH scaffold TGF-β, Smad3 and α-SMA histochemical section pictures.

[0042] Note: (A) Representative staining pictures of TGF-β, Smad3 and α-SMA; (B) Quantitative analysis of TGF-β, Smad3 and α-SMA

[0043] Figure 9 Figure legends for the ZFBH scaffold TNF-α, IL-10 histochemical section pictures.

[0044] Note: (A) Representative staining pictures of TNF-a and IL-10; (B) Quantitative analysis of TNF-a and IL-10

[0045] Figure 10 Figure 4: Representative pictures of CD31 staining of ZFBH scaffold

[0046] Note: (A) Representative staining pictures of CD31; (B) Quantitative analysis of CD31

[0047] Figure 11 Figure 5: Representative pictures of H&E staining of ZFBH scaffold

[0048] Note: Representative H&E staining pictures of heart, liver, spleen, lung, kidney of Control group and ZFBH scaffold group are shown in the figure Figure 12 Figure 6: Simulation of the scheme of the present application DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] In the following examples, the methods used are conventional methods and can be obtained from literature, unless otherwise specified.

[0051] In the following examples, the consumables used can be purchased on the market, unless otherwise specified.

[0052] Example 1, preparation of SG scaffold

[0053] (1) Dissolve gelatin (3 g) in deionized water (100 mL) under 50 °C water bath, then add sodium alginate (6 g) and stir uniformly;

[0054] (2) Put the mixture obtained in step (1) into a 3D printing cartridge, and the 3D printer is printed;

[0055] (3) After printing, immerse the sample obtained in step (3) in a calcium chloride solution (2% w / v) and store overnight to obtain the SG scaffold.

[0056] Example 2, preparation of FeH scaffold

[0057] (1) Dissolve gelatin (3 g) in deionized water (100 mL) under 50 °C water bath, then add sodium alginate (6 g) and stir uniformly;

[0058] (2) Add iron powder (1 g) into the hydrogel obtained in step (1) and stir until uniform;

[0059] (3) Load the mixture obtained in step (2) into a 3D printing cartridge and print using a 3D printer;

[0060] (4) After printing, immerse the sample obtained in step (3) in a calcium chloride solution (2% w / v) and store overnight to obtain the FeH scaffold.

[0061] Example 3, Preparation of ZnH scaffold

[0062] (1) Dissolve gelatin (3 g) in deionized water (100 mL) at 50 °C water bath, then add sodium alginate (6 g) and stir until uniform;

[0063] (2) Add zinc powder (1 g) into the hydrogel obtained in step (1) and stir until uniform;

[0064] (3) Load the mixture obtained in step (2) into a 3D printing cartridge and print using a 3D printer;

[0065] (4) After printing, immerse the sample obtained in step (3) in a calcium chloride solution (2% w / v) and store overnight to obtain the ZnH scaffold.

[0066] Example 4, Preparation of PAM hydrogel

[0067] (1) Under ice bath, add ammonium persulfate (0.05 g), N,N'-methylenebisacrylamide (0.003 g), acrylamide (2.5 g), and tetramethylethylenediamine (20 μL) into 12.5 mL of deionized water in sequence to form a transparent pre-polymerization solution;

[0068] (2) Pour the solution obtained in step (1) into a mold and place in a 60 °C oven for 30 min to form a PAM hydrogel.

[0069] Example 5, Preparation of PDM hydrogel

[0070] (1) Dissolve different amounts of dopamine (0.005 g, 0.01 g, 0.02 g, and 0.03 g) in 12.5 mL of alkaline (pH = 12) aqueous solution and stir for 20 min. The solution gradually turns brown;

[0071] (2) Under ice bath, add ammonium persulfate (0.25 g), N,N'-methylenebisacrylamide (0.003 g), acrylamide (2.5 g), and tetramethylethylenediamine (20 μL) into the solution obtained in step (1) in sequence to form a brown pre-polymerization solution;

[0072] (3) Pour the solution obtained in step (2) into a mold, and place it in an oven at 60°C for 30 min to form a PDM hydrogel with adhesion. According to different mass ratios of dopamine / acrylamide, it can be named as 0.2% PDM, 0.4% PDM, 0.8% PDM and 1.2% PDM in turn.

[0073] Example 6, Preparation of ZFBH scaffold

[0074] (1) Dissolve gelatin (6 g) in deionized water (200 mL) at 50°C water bath, then add sodium alginate (12 g) and stir uniformly;

[0075] (2) Divide the solution obtained in step (1) into two parts, and add iron powder (1 g) and zinc powder (1 g) respectively, and stir uniformly;

[0076] (3) Put the mixture obtained in step (2) into a 3D printing cartridge, and use double-nozzle 3D printing technology for printing;

[0077] (4) After printing, immerse the sample obtained in step (3) in a calcium chloride solution (2% w / v) and store overnight to obtain ZnH scaffold and FeH scaffold;

[0078] (5) Dissolve dopamine (0.02 g) in an alkaline (pH = 12) aqueous solution and stir for 20 min. The solution gradually turns brown;

[0079] (6) Under ice bath, add the solution obtained in step (5) to ammonium persulfate (0.25 g), N,N'-methylenebisacrylamide (0.003 g), acrylamide (2.5 g), and tetramethylethylenediamine (20 μL) in turn to form a brown pre-polymerization solution;

[0080] (7) Pour the solution obtained in step (6) into a mold, immerse one end of the ZnH scaffold obtained in step (4) into the mold, and place it in an oven at 60°C for 30 min to form a ZFBH scaffold with adhesion. Its preparation process and principle are shown in Figure 12 .

[0081] Example 7, Gelation properties and adhesion properties of PAM hydrogel and PDM hydrogel

[0082] The PAM of Example 4 and PDM hydrogels of different concentrations in Example 5 were used as experimental objects for the following experiments: the pre-polymerization solution was poured into a glass bottle, placed at 60°C for 30 min, and the glass bottle was inverted to observe whether it was gelled. At the same time, the pre-polymerization solution was poured into a square mold with a length of 10 mm, a width of 5 mm, and a thickness of 1 mm, and was crosslinked at 60°C for 30 min. The sample was adhered to the pig skin, and the adhesion properties of different PAM hydrogels and PDM hydrogels were evaluated by a universal mechanical testing machine (AGS-X5KN, Shimadzu, Japan). The adhesion properties of PDM to different material surfaces were also evaluated.

[0083] Figure 1 A is the evaluation of the gelation properties of the scaffolds prepared in Examples 4 and 5. As can be seen from the figure, except for 1.2% PDM which cannot gel, the hydrogels of various concentrations all achieve gelation. Subsequently, the tensile test of PAM hydrogel, 0.2% PDM, 0.4% PDM, 0.8% PDM gel and pig skin showed that the adhesion properties of 0.8% PDM gel were the best Figure 1 B), which confirmed that the introduction of dopamine can enhance the adhesion properties of the composite system, and when the concentration is less than or equal to 0.8%, the adhesion properties are positively correlated with the concentration. Therefore, the optimal concentration of 0.8% PDM was selected for subsequent experiments. At this concentration, the hydrogel has excellent adhesion properties and can adhere to the surfaces of various objects such as plastic, glass, ear cleaning balls, and weights Figure 1 C).

[0084] Example 8, microcharacterization of FeH scaffolds, ZnH scaffolds and ZFBH scaffolds

[0085] In this experiment, the FeH scaffolds, ZnH scaffolds and ZFBH scaffolds of Examples 2, 3 and 6 were used as experimental objects for the following experiments: the structure and morphology of the printed hydrogel scaffolds were observed, and the printed scaffolds were freeze-dried to observe the morphology of the hydrogel scaffolds by scanning electron microscopy (SEM, JEOL JSM-6701F). After freeze-drying the gel sample into powder, the structure and phase composition of the synthesized sample were characterized by X-ray diffraction (XRD, Rigaku D / Max-2400 diffractometer, CuKα radiation and graphite monochromator, ).

[0086] The actual picture of the FeH scaffold prepared in Example 2 is shown in Figure 2 A, the actual picture of the ZnH scaffold prepared in Example 3 is shown in Figure 2 B, and the actual picture of the ZFBH scaffold prepared in Example 6 is shown in Figure 2C. As can be seen from the figure, the ZnH scaffold is silver-white in color; the FeH scaffold is black in color; the ZFBH scaffold has a double-layer structure of silver-white and black, and has a layer of brown structure (PDM) on the surface of the silver-white layer (ZnH scaffold).

[0087] Figure 3 Microscopic characterization of the FeH scaffold, ZnH scaffold and ZFBH scaffold prepared for Example 2, Example 3 and Example 6. Under low-magnification SEM, Figure 3 A. The FeH scaffold and Figure 3 B. The ZnH scaffold all present good morphology without collapse. Through EDS mapping test, it can be detected that Fe element and Zn element are evenly distributed in the FeH scaffold Figure 3 C) and ZnH scaffold Figure 3 D) respectively, which confirms that the metal powder can be evenly distributed in the scaffold. Notably, Figure 3 B. The PDM of the ZnH scaffold can be observed to fill the scaffold and form many micropores. EDS mapping confirms that Zn element is distributed on the main body of the scaffold Figure 3 D).

[0088] Further magnification can observe micron-sized particles on the surface of the FeH scaffold and ZnH scaffold respectively Figure 3 E-F). XRD analysis confirms that the FeH scaffold has characteristic peaks at 44.7°, 65.0° and 82.3°, corresponding to the (110), (200) and (211) crystal planes of Fe Figure 3 G). In contrast, the ZnH scaffold has characteristic peaks at 36.3°, 39.0° and 43.2°, corresponding to the (002), (100) and (101) crystal planes of Zn Figure 3 H), consistent with the standard PDF card. These findings indicate the formation of various metal microelectrode structures in the entire SG scaffold hydrogel electrolyte.

[0089] Figure 3 I. The cross-sectional SEM results show that the ZFBH scaffold has a porous structure, which can provide channels for cell migration. Figure 3 J-K. The EDS mapping results clearly show the distribution characteristics of elements in the scaffold material. According to the images, it can be shown that the iron element is mainly concentrated in the upper layer of the scaffold, while the zinc element is more distributed in the lower layer of the scaffold. The arrangement of these two elements corresponds to the cathode layer and anode layer of the scaffold. Therefore, it is confirmed that the integrated construction of the ZFBH scaffold can be realized through the application of the double-nozzle 3D printing technology. In addition, the XRD results confirm that the ZFBH scaffold shows characteristic peaks of Fe and Zn consistent with the standard PDF card Figure 4L). In summary, a porous hydrogel formed by Zn and Fe elements was characterized by microstructure, with the upper layer being the Fe electrode, the lower layer being the Zn electrode integrated with the PDM-adhesive hydrogel, and having seamless connection between them.

[0090] Example 9, electrical performance of ZFBH scaffold

[0091] In this experiment, PAM, PDM and ZFBH scaffolds in Examples 4, 5 and 6 were used as the implementation object for the following experiments: The gel samples were packaged with high-purity copper foil, copper wires were led from the cathode and anode, and were immersed in 100 mL PBS buffer. It was connected to a high-precision multimeter, and the effective output voltage at different times (0h, 12h, 24h, 72h, 168h) was measured and recorded. In addition, PAM and PDM were used as the implementation object, and electrochemical impedance spectroscopy (EIS) measurement was performed using an electrochemical workstation (760E, CHI), with a scanning frequency range of 100 kHz to 0.1 Hz and an open circuit potential of 0.1 V. The hydrogel with a length of 8 mm, a width of 9 mm and a thickness of 2 mm was placed between two platinum electrodes (10 mm x 10 mm) in a custom-made quartz cuvette, surrounded by PBS buffer solution. An Ag / AgCl electrode (containing 3M KCl) was used as the reference electrode.

[0092] Figure 4 A i is the voltage output characterization of the ZFBH scaffold prepared in Example 6, it can be seen that the voltage can be stabilized at about 0.45V, 0.35V, 0.28V, 0.21V and 0.12V at 0h, 12h, 24h, 72h and 168h respectively, which confirms that it can meet the long-lasting electrical stimulation for at least 7 days. In addition, among the properties of the hydrogel required to construct the ZFBH scaffold, electrical conductivity is the key to transmitting electrical stimulation to the skin tissue.

[0093] Figure 4 A ii-iii is the impedance performance test of the hydrogel, and the results of Bode plot and Nyquist plot confirm that the impedance of PDM is lower and the ionic conductivity is higher compared with PAM due to the introduction of dopamine PDA, which indicates that PDM has excellent electrical conductivity and can reduce the interface resistance between the ZFBH scaffold and the skin tissue.

[0094] Example 10, free radical scavenging ability characterization chart

[0095] In this experiment, SG scaffolds, FeH scaffolds, ZnH scaffolds, PDM hydrogels and ZFBH scaffolds in Examples 1, 2, 3, 5 and 6 were used as the experimental object for the following experiments:

[0096] (1) Hydroxyl radical detection: 1.8 mM FeS04 aqueous solution, 1.8 mM salicylic acid-ethanol / water solution, 1.8 mM salicylic acid-water solution and 0.03% H2O2 solution were prepared. 2 mL of 1.8 mM FeS04 aqueous solution, 1.5 mL of 1.8 mM salicylic acid-ethanol solution and 0.1 mL of 0.03% H2O2 were mixed, and 0.1 g of hydrogel sample was added, and reacted at 37°C for 30 min. Full wavelength scanning was performed using a UV spectrophotometer, and the absorbance values of each group of samples at a wavelength of 510 nm were recorded.

[0097] Hydroxyl radical scavenging rate = [A0-(A x -A x0 )] / A0*100%

[0098] Note: A0 is the absorbance of the blank control (no sample, add chromogenic agent H2O2); Ax is the absorbance of the sample with H2O2; Ax0 is the absorbance without sample and without chromogenic agent (H2O2).

[0099] (2) DPPH scavenging ability detection: 100 μL of 0.1 mmol / mL DPPH-ethanol solution was mixed with 0.1 g of hydrogel sample, and reacted at room temperature for 30 min in the dark, followed by centrifugation at 5000 rpm for 5 min to precipitate the hydrogel material. Full wavelength scanning was performed using a UV spectrophotometer, and the absorbance values of each group of samples at a wavelength of 517 nm were recorded.

[0100] DPPH scavenging rate (%) = (1-A t / A0) * 100%

[0101] Note: A t and A0 are the absorbance values of the test group and the blank group at 517 nm, respectively.

[0102] (3) ABTS scavenging ability detection: 0.3 g of ABTS diammonium salt was dissolved in 80 mL of deionized water as a liquid, and 0.025 g of the solution was dissolved in 80 mL of deionized water as b liquid. The a liquid and the b liquid were mixed and darkly oxidized for 12 hours. When used, it was diluted 30 times and mixed with 0.1 g of hydrogel sample, and reacted for 30 min. Full wavelength scanning was performed using a UV spectrophotometer, and the absorbance values of each group of samples at a wavelength of 734 nm were recorded.

[0103] ABTS scavenging rate (%) = (1-A t / A0) * 100%

[0104] Note: A t and A0 are the absorbance values of the test group and the blank group at 734 nm, respectively.

[0105] Figure 5 B is the radical scavenging rate test of SG scaffold, FeH scaffold, ZnH scaffold, PDM, ZFBH scaffold in embodiments 1, 2, 3, 5, 6. It can be seen from the figure that the generation of hydroxyl radicals can be enhanced by simply connecting the electric stimulation, but it depends on Zn, Fe as reducing agent and the antioxidant ability of PDA. The scavenging efficiency of OH, DPPH and ABTS of ZFBH scaffold is 88.6%, 92.0%, 91.6% respectively, which can be attributed to the acceleration of Zn-Fe electrode and the combined effect of PDM. It shows that ZFBH scaffold has strong antioxidant ability, which confirms that the hydrogel is expected to eliminate reactive oxygen species (ROS) and reactive nitrogen species (RNS) at the wound site, and provide a suitable microenvironment for wound healing.

[0106] Example 11, CCK-8 experiment

[0107] In this experiment, SG scaffold, PDM, ZFBH scaffold in embodiments 1, 5, 6 are used as the implementation object for the following experiments: a number of gel samples of similar size in each group are prepared in advance, and the samples are thoroughly sterilized by ultraviolet (UV) irradiation. The ZFBH scaffold is set at a concentration gradient of 0.5% w / v, 1% w / v and 2% w / v. L929 cells are used, and a 24-well plate is used for CCK-8 test for 1, 3, 5 and 7 days. 1×10 4 cells are added to each well for co-culture with the sample. After a fixed number of days of culture, an appropriate amount of MTT reagent is added, and incubated at 37°C for 4h. Discard the supernatant, and add dimethyl sulfoxide to dissolve the purple formazan crystals. Shake the plate on a shaker at room temperature for 15 minutes to dissolve the crystals evenly. Then transfer the liquid in the 24-well plate to a 96-well plate. Measure the absorbance value at OD 450nm by enzyme labeler. Three duplicate wells are set for each group.

[0108] Figure 5 A is the CCK-8 cell compatibility test of SG scaffold, PDM, ZFBH scaffold in embodiments 1, 5, 6. The results show that the cell viability of SG scaffold and PDM is greater than 85% at 1, 3, 5 and 7 days, which meets the requirement of cell compatibility. ZFBH scaffold at a concentration of 2% cannot meet the biocompatibility requirement. ZFBH scaffold at a concentration of 1% has excellent activity in promoting cell proliferation compared with the blank group and the SG scaffold group, which can be attributed to the generation of micro-current. Therefore, the optimal concentration of ZFBH scaffold is selected as 1% for subsequent experiments.

[0109] Example 12, Calcein-AM / PI live / dead cell staining

[0110] This experiment used the SG scaffold, FeH scaffold, ZnH scaffold, PDM, and ZFBH scaffold from Examples 1, 2, 3, 5, and 6 as the subjects for the following experiments: cell culture and material sterilization procedures were the same as above. 1×10⁶ cells were seeded in 24-well plates. 4 Cells were cultured with the material for 1, 3, 5, and 7 days. The supernatant was then discarded, and the cells were washed with PBS buffer. Using the Calcein-AM / PI live / dead cell staining assay kit, the cells were stained in an incubator at 37°C for 0.5 hours. The staining solution was aspirated to terminate the incubation. An appropriate amount of PBS buffer was added to each well to cover the cells. Live cells (yellow-green fluorescence) and dead cells (red fluorescence) were then observed and photographed using an inverted fluorescence microscope.

[0111] Live / dead cell staining is used to observe cell viability after the CCK-8 assay, such as... Figure 5 As shown in Figure B, almost no dead cells with red fluorescent labeling were observed. Furthermore, the ZFBH scaffold hydrogel exhibits superior cell proliferation promotion capabilities, with better cell morphology, meeting cell compatibility requirements.

[0112] Example 13, Hemolysis Experiment

[0113] This experiment used the SG scaffold, FeH scaffold, ZnH scaffold, PDM, and ZFBH scaffolds from Examples 1, 2, 3, 5, and 6 as the subjects for the following experiments: A suitable amount of whole blood from healthy SPF rats was taken, and 3.8 wt% sodium citrate-physiological saline solution was added, followed by dilution with physiological saline at a volume ratio of 4:5. The sample was placed in 10 mL of physiological saline and incubated at 37°C for 30 min. Then, 0.2 mL of diluted blood was added and cultured for 1 hour. Physiological saline and deionized water served as the negative and positive control groups, respectively. All test tubes were centrifuged at 1000 rpm for 5 minutes. The supernatant was transferred to a 96-well plate. The absorbance (optical density, OD) was read at 545 nm using a microplate reader to calculate the hemolysis rate.

[0114] Figure 5 The hemolysis experiment shown in C also confirmed that the hemolysis rate in all groups was less than 5%, meeting the requirements of the international standard (ISO standard number: 10993-4), demonstrating good blood safety.

[0115] Example 14, Scratch Test

[0116] The SG scaffold, FeH scaffold, ZnH scaffold, PDM, and ZFBH scaffold in Examples 1, 2, 3, 4, 5 were used as the implementation objects for the following experiment: cells were inoculated using a six-well plate, and then the scaffold was co-cultured with the cells. After the cell spreading area reached 90%, the plate was scratched using a 20 μL pipette, washed twice with PBS, and then replaced with serum-free basal medium to eliminate the influence of cell self-proliferation on the experiment. Under the same conditions, the same microscope (Nikon ECLIPSE80i / DS-Ri2 / NIS-Elements D, Nikon, Japan) was used to observe the changes in the scratch area at 0 h, 24 h, and 48 h and take pictures.

[0117] Figure 6 In D, the effect of the ZFBH scaffold on cell migration was studied using a wound scratch test, and a micro-current was generated using a lead device. No significant difference was observed in the cell migration distance of the control group and the PDM group. However, the cell migration distance of the FeH scaffold and the ZnH scaffold increased to some extent, which could be attributed to the improvement of cell migration ability caused by ion release. The cell migration distance of the ZFBH scaffold group at the 24 h mark increased significantly, and the scratch was completely healed at 48 h. This indicates that the micro-current and ion release of the ZFBH scaffold can significantly enhance the migration of L929 and accelerate the healing of the wound.

[0118] Example 15, antibacterial experiment

[0119] The SG scaffold, FeH scaffold, ZnH scaffold, PDM, and ZFBH scaffold in Examples 1, 2, 3, 5, 6 were used as the implementation objects for the following experiment: E. coli and S. aureus were inoculated into Luria Bertani medium and cultured at 37°C at a speed of 200 rpm on an orbital shaker for 12 h, and then the bacteria were collected by centrifugation. The hydrogel sample was cut into a circle with a diameter of about 1 cm, and then placed in a sterile centrifuge tube containing 10 mL of bacterial suspension (10 5 -10 6 CFU / mL). The centrifuge tube was shaken at 37°C for 30 min using a shaker, and then 100 μL of the suspension was taken and mixed with 20 mL of agar medium. After incubation at 37°C for 12 h, the total number of colonies appearing on the culture plate was counted. Three parallel samples were taken for each experimental group.

[0120] Figure 6The results of A show that the antibacterial effect is in the order of PDM < FeH support < ZnH support < ZFBH support. It is found that PDA can destroy the structural integrity of the bacterial cell membrane through protein chelation and electrostatic effects. The antibacterial effect of FeH support involves an increase in membrane permeability, loss of proton energy, leakage of cell contents, and disruption of DNA replication. In addition, the antibacterial effect of ZnH support is stronger, which can be attributed to the release of Zn 2+ , which can interfere with metalloproteins, leading to protein dysfunction and bacterial cell instability. The inhibition rate of the ZFBH support group on bacteria is close to 100%, which can be attributed to the synergistic effect of the above-mentioned components, achieving the optimal antibacterial effect. Therefore, in this study, the antibacterial efficacy depends on the release of natural ions and electrical stimulation, effectively alleviating the drawbacks of antibiotic resistance.

[0121] Example 16, RT-qPCR

[0122] In this experiment, the SG support, FeH support, ZnH support, PDM, and ZFBH support in Examples 1, 2, 3, 5, and 6 were used as the implementation objects for the following experiments: L929 cell lines (Shanghai Fusheng Industry Co., Ltd., X120311) were seeded into 24-well plates at a density of 20000 cells / well and co-cultured in DMEM medium for 3 days to detect the expression of TGF-β and Smad3 genes. RAW264.7 cell lines (Hunan Fenghui Biological Technology Co., Ltd., CL0266) were used to analyze the expression of TNF-α and IL-10 genes. HUVEC cell lines (ScienCell Research Laboratories, Cat. #8000) were used to detect the expression of HIF-1α and VEGF genes. The cells were digested to ensure that the number of cells in each group was not less than 1 × 10 6 RNA was extracted from the cells, and the total RNA concentration was measured. Subsequently, cDNA was reverse transcribed for amplification of the target genes, followed by qPCR reaction to calculate the mRNA expression.

[0123] Figure 6 The results of B show that the ZFBH support can activate the TGF-β / Smad3 signaling pathway in vitro Figure 6 B i); can down-regulate the expression of pro-inflammatory gene TNF-α and up-regulate the expression of anti-inflammatory gene IL-10 Figure 6 B ii); and promote the expression of angiogenesis-related genes depending on the HIF-1α / VEGF signaling pathway Figure 6 B iii). It is confirmed that the ZFBH support group exhibits the most prominent up-regulation of repair genes and significant effects on inflammation regulation and angiogenesis Figure 7 B iv).

[0124] Example 17, Evaluation of the effect of ZFBH scaffold on wound healing

[0125] With the approval of the animal ethics committee, several healthy SPF rats were selected to study the ability of various hydrogels to promote full-thickness skin defect wound healing. The rats were anesthetized by intraperitoneal injection of 10% urethane (10% urethane / rat body weight = 0.4 mL / 100 g). Two circular full-thickness wounds (1.0 cm in diameter) were made on the back of each mouse. The surgical wound surface was covered with hydrogel. On the 4th, 7th, 14th and 16th day, the mice were anesthetized with an overdose of urethane, and the wounds were photographed at the same time. The wound size measured by ImageJ was used to calculate the percentage of wound reduction. Then the wound and adjacent normal skin were excised, fixed with 4% paraformaldehyde, dehydrated by gradient, paraffin-embedded and sectioned, then H&E staining, Masson staining and immunohistochemical staining (COL-I, COL-III) were performed, and observed under an optical microscope, and the healing status and indicators of the defect tissue were analyzed and evaluated.

[0126] As shown in Figure 7 To explore the effect of ZFBH scaffold dressing on wound healing, we established a full-thickness skin defect model with a diameter of 1 cm on the back of SPF rats. In the animal experiment, the main effect of the dressing itself was explored, and all the hydrogel bottoms were constructed with adhesive PDM hydrogel to achieve a "suture-free" fixed dressing. As shown in Figure 7 As shown in A-B, on the 4th and 7th day of wound healing, FeH scaffold and ZnH scaffold both significantly accelerated wound healing compared with the blank group and silicone-based dressing group (MS) group, which indicated that the ions released by metal hydrogel played a key role in promoting wound healing. However, on the 14th and 16th day, the healing effect of FeH scaffold group was comparable to that of the blank group and MS group, which indicated that it mainly promoted early wound healing, but had limited scar remodeling ability, which may be due to the excessive proliferation of collagen and blood vessels caused by iron ion release. In contrast, the surface healing of the ZnH scaffold group was smoother, and the scar had a decreasing trend. In addition, the healing ability of the ZFBH scaffold group was the strongest, reaching complete healing on the 14th day and scar-free healing on the 16th day, which meant that the galvanic reaction of the two metals played a more significant role in promoting wound healing, which was obviously superior to the silicone-based wound dressing on the market (MS group).

[0127] The wound healing was evaluated by H&E staining method Figure 7C). At day 4 of skin healing, all groups showed similar healing processes, including granulation tissue infiltration and an obvious inflammatory response. The inflammatory response was lighter in the ZnH scaffold group compared to the FeH scaffold group, while the inflammatory response was most obvious in the MS group. By day 7, the number of inflammatory cells and discontinuous epidermis were significantly reduced in each group. Notably, the FeH scaffold group showed stronger vascularization ability compared to the ZnH scaffold group. By day 16, continuous epithelium and skin appendages appeared in all groups, but there were significant differences in histology, especially the thickening of the epithelium observed in the FeH scaffold group. In contrast, the ZFBH scaffold group showed beneficial anti-inflammatory and vascular effects in the early stage, and transitioned to tissue remodeling in the later stage, with more complete epithelium and increased formation of hair follicle structures, thus meeting the morphological and functional requirements of skin tissue healing.

[0128] Subsequently, Masson staining and corresponding collagen quantification results showed that the collagen content continued to increase over time. During the healing phase of the wound, the collagen content in the ZnH scaffold, FeH scaffold, and ZFBH scaffold groups was always superior to that in the Control and MS groups Figure 7 D). Compared to the two metals, the ZnH scaffold group showed higher collagen content at day 4, which can be attributed to the ZnH scaffold, while the FeH scaffold group reached the highest level at day 7. This observation suggests that the two hydrogels play different roles in the inflammatory and repair phases of wound healing, thus effectively promoting collagen deposition and accelerating the tissue repair process. It is worth mentioning that due to the introduction of electrical stimulation, the collagen deposition in the ZFBH scaffold hydrogel group reached the highest level at days 4 and 7. By day 16, the collagen content was expressed, but showed a more orderly arrangement, which can be attributed to collagen remodeling, which is more conducive to scarless healing.

[0129] Collagen fibers in the skin are mainly composed of type I collagen (COL-I) and type III collagen (COL-III), with COL-I being relatively thick and playing an important role in maintaining skin hardness and tightness. However, excessive COL-I can cause skin stiffness and form scars after wound healing. In contrast, COL-III is the main component of skin reticular fibers, and the higher the content, the finer the fiber bundles, and the smoother the skin tissue. Therefore, to further evaluate the effect of ZFBH scaffold on scarless healing, we performed immunohistochemical (IHC) staining at day 16 to evaluate the expression of COL-I and COL-III. The results showed that the ZFBH scaffold group had significantly reduced COL-I expression and increased COL-III expression compared to other groups, and the ratio of COL-I to COL-III was closer to the level of normal skin Figure 8E-F). This finding supports the view that the ZFBH scaffold group is more inclined to scarless healing, and its healing mechanism includes accelerating the initial rapid healing and promoting the remodeling of ECM in the subsequent stage.

[0130] Example 18, Mechanism of ZFBH scaffold to promote wound healing

[0131] The healing of wound can be generally divided into three stages: inflammation, repair and remodeling. In order to explore the mechanism of ZFBH scaffold to promote scarless wound healing, the expression of repair-related proteins (TGF-β, Smad3, α-SMA), inflammation-related proteins (TNF-α, IL-10) and angiogenesis-related proteins (CD31) were evaluated by IHC staining.

[0132] During the wound healing process, the TGF-β / Smad3 / α-SMA signaling pathway plays a key role in wound healing and scar formation. As shown in Figure 9 As shown in IHC staining and related quantitative analysis of A-B, the expression of related proteins in ZFBH scaffold group was the highest at day 4 and day 7, but significantly decreased at day 16. This indicates that the ZFBH scaffold based on bioelectric stimulation can up-regulate the TGF-β / Smad3 / α-SMA signaling pathway in the inflammation and proliferation stages of wound healing, promote the rapid proliferation of fibroblasts, and accelerate the initial healing, thereby shortening the overall healing time. In addition, the significant decrease of these markers in the remodeling stage helps to prevent the excessive proliferation of fibroblasts, thereby minimizing the risk of scar formation. This result confirms that the ZFBH scaffold enhances the dynamic regulation ability of the TGF-β / Smad3 / α-SMA signaling pathway, promotes the accelerated healing of wounds, and at the same time ensures scarless recovery.

[0133] Inflammatory factors play a key role in regulating the immune microenvironment during wound healing, which is crucial for accelerating healing and achieving scarless results. As shown in Figure 10As shown in A-B, it was observed that at day 4 and day 7 of wound healing, pro-inflammatory cytokine TNF-a was highly expressed in the control group, MS group, and FeH scaffold group, while anti-inflammatory cytokine IL-10 was barely detectable. In contrast, the ZnH scaffold group and ZFBH scaffold group showed downregulation of TNF-a and upregulation of IL-10 expression. By day 16, the ZnH scaffold group and ZFBH scaffold group showed little sign of inflammation or infection, with only minimal levels of TNF-a, and reduced levels of anti-inflammatory factors such as IL-10. These findings suggest that the ZnH scaffold has superior anti-inflammatory effects compared to the FeH scaffold. Zn2+ is known to play an important role in innate immunity, and previous studies have confirmed that Zn2+ can inhibit the NF-kB signaling pathway, thereby exerting anti-inflammatory activity. This chemical signal ensures a smooth transition during the inflammatory phase of wound healing. The minimal inflammatory response in the ZFBH scaffold group can be attributed to the dual action of Zn2+ release and bioelectric stimulation.

[0134] Angiogenesis is crucial for early-stage accelerated wound healing. CD31, a marker for endothelial cells, was used to label newly formed vascular endothelial cells. As shown in A-B, all experimental groups showed significant CD31 expression at day 7, particularly in the FeH scaffold group and ZFBH scaffold group. These findings suggest that the level of vascularization at the wound site is high, and newly formed blood vessels promote early-stage rapid healing. However, excessive angiogenesis in the later stages can lead to scar formation. By day 16, the FeH scaffold group still showed high levels of vascular marker expression, while the ZFBH scaffold group showed the lowest level of expression, indicating that vascular degradation and remodeling occurred under the influence of physical electric stimulation. This observation highlights that the ZFBH scaffold not only promotes angiogenesis and accelerates wound healing during the inflammation and repair stages, but also promotes vascular degradation during the remodeling stage, thereby minimizing the formation of scars. Figure 11

[0135] In summary, the IHC results confirm that the ZFBH scaffold can accelerate early-stage wound healing during the inflammation and repair stages by applying physical electric stimulation and chemical ionic stimulation to the wound defect tissue. This acceleration is achieved by activating the TGF-b / Smad / a-SMA signaling pathway, modulating inflammation (downregulating TNF-a and upregulating IL-10), and promoting angiogenesis (upregulating CD31), resulting in early rapid healing of the wound, which not only achieves remodeling of the microenvironment but also prevents the wound from developing into a chronic wound. Furthermore, during the remodeling stage of wound healing, the ZFBH scaffold inhibits the TGF-b / Smad3 / a-SMA signaling pathway and promotes degradation and remodeling of the vascular matrix, making rapid and scarless healing of the wound possible.

[0136] Example 19, In vivo toxicity assessment of ZFBH scaffold​

[0137] After perfusion of the heart of rats (16 days) in the Control group and the ZFBH scaffold group, the heart, liver, spleen, lung and kidney tissues were taken out and immersed in a fixing solution. Subsequently, after gradient dehydration, paraffin embedding and sectioning, H&E staining was performed, and the tissues were observed under an optical microscope.

[0138] ​ The experimental results of the ZFBH scaffold group showed that compared with the Control group, no obvious visceral injury was shown, the tissue structure remained intact, the cell arrangement was regular, and there was no significant abnormality in the nuclear-cytoplasmic ratio and cell morphology. This initially indicated that the ZFBH scaffold could meet the clinical safety requirements and had clinical transformation potential.

[0139] In summary, (1) the present application uses direct writing type 3D printing technology to prepare a self-power-generating hydrogel scaffold, which has excellent biocompatibility, stable and long-lasting voltage output, and exhibits excellent effects of promoting scar-free healing of wounds; provides a suitable survival environment and induction environment for cells in the wound healing site, simulates and amplifies endogenous electrical stimulation, cascade regulates the expression of wound site repair related genes, and reduces the expression of pro-inflammatory factors and accelerates the vascularization of the wound site, promotes the scar-free healing of the wound.

[0140] (2) The self-power-generating hydrogel scaffold prepared in the present application uses the solid and liquid dual characteristics of hydrogel, based on the solid characteristics to play a function similar to a battery separator, and based on the liquid characteristics to act as an electrolyte and promote ion transmission, effectively solving the problem of complex structure caused by the need to build a separator in traditional batteries.

[0141] (3) The self-power-generating hydrogel scaffold prepared in the present application has multiple repair mechanisms such as physical stimulation and chemical stimulation, including the release of zinc ions to play an anti-inflammatory role, the release of iron ions to play a pro-angiogenic role, the excellent antioxidant performance of each component unit, the continuous generation of bioelectricity to promote tissue remodeling, and the realization of scar-free healing of wounds, effectively avoiding the single action and low effect of traditional dressings.

[0142] (4) The self-power-generating hydrogel scaffold prepared in the present application constructs an adhesion layer at one end near the wound, which avoids the shedding of the dressing during use to exert long-lasting bioelectric stimulation.

[0143] (5) The self-power-generating hydrogel scaffold prepared in the present application is based on the method of 3D printing additive manufacturing, which is easy to quickly, batch, scale, and personalize production, and has a broad market prospect in the field of skin tissue repair, providing a new treatment scheme for accelerating the scar-free healing of wounds.

[0144] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A 3D printed self-powering hydrogel scaffold, characterized in that, The self-power-generating hydrogel scaffold comprises an anode scaffold and a cathode scaffold, the anode scaffold is a zinc-containing hydrogel obtained by 3D printing, and the cathode scaffold is an iron-containing hydrogel obtained by 3D printing.

2. The self-powering hydrogel scaffold of claim 1, wherein, The concentration of zinc and iron in the hydrogel is 0.5%-1% w / v.

3. The self-powering hydrogel scaffold of claim 1, wherein, The hydrogel is prepared by adding gelatin into deionized water and then adding sodium alginate.

4. The self-powering hydrogel scaffold of claim 1, wherein, The anode scaffold is further wrapped with a prepolymerization solution, and the prepolymerization solution is prepared from dopamine, ammonium persulfate, N, N'-methylene bisacrylamide, acrylamide and tetramethyl ethylenediamine.

5. The self-powering hydrogel scaffold of claim 4, wherein, In the prepolymerization solution, the ratio of dopamine to acrylamide is 0.2-1.2% w / t; the ratio of ammonium persulfate to acrylamide is 10% w / t; the ratio of N, N'-methylene bisacrylamide to acrylamide is 0.12% w / t; and the volume ratio of tetramethyl ethylenediamine to water solvent is 1:

625.

6. The method for preparing a self-power-generating hydrogel scaffold according to any one of claims 1-5, wherein, The method comprises the following steps: (1) dissolving gelatin in deionized water, adding sodium alginate and stirring uniformly; (2) dividing the solution obtained in step (1) into two parts, adding zinc powder and iron powder respectively, stirring uniformly to obtain anode scaffold material and cathode scaffold material; (3) loading the anode scaffold material and the cathode scaffold material obtained in step (2) into a 3D printing cartridge, printing using a double-nozzle 3D printing technology, soaking in a calcium chloride solution, and storing overnight to obtain an anode scaffold and a cathode scaffold; (4) dissolving dopamine in an alkaline aqueous solution and stirring until the solution turns brown; (5) under ice bath, adding ammonium persulfate, N, N'-methylene bisacrylamide, acrylamide and tetramethyl ethylenediamine to the solution obtained in step (4) in sequence to form a brown prepolymerization solution; (6) pouring the solution obtained in step (5) into a mold, soaking one end of the anode scaffold obtained in step (3) in the mold, and placing in a 60°C oven for 30 min to form a ZFBH scaffold with adhesion.

7. The production method according to claim 6, wherein Step (1) is carried out under heating, and the mass / volume ratio of zinc powder or iron powder to deionized water in step (2) is 0.5%-2% (w / v); the concentration of the calcium chloride solution in step (3) is 1%-5% (w / v).

8. The production method according to claim 6, wherein The pH value of the alkaline aqueous solution in step (4) is 10-14.

9. Use of the self-power-generating hydrogel scaffold according to any one of claims 1-5 or prepared by the preparation method according to any one of claims 6-8 in the preparation of skin repair materials.

10. Use of the self-power-generating hydrogel scaffold according to any one of claims 1-5 or prepared by the preparation method according to any one of claims 6-8 in the preparation of skin damage treatment dressings.

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