Silver nanowire-enhanced injectable conductive particle hydrogel, method of preparation and use thereof

Abstract

The present application relates to the technical field of composite material preparation, in particular to a kind of silver nanowire reinforced injectable conductive particle hydrogel, preparation method and application thereof, by controllable electrostatic force self-assembly synthesized by two kinds of particles consisting of conductive particle hydrogel, the particle hydrogel has superior injectability, antibacterial performance, mechanical property and conductive performance, can effectively transmit electric stimulation signal.The particle hydrogel can fully adapt to irregular wound, and the effect is better than that of chemical crosslinking polymer bulk hydrogel;And have good mechanical property, can be fully retained in the wound surface under the motion scene, and the effect is better than that of particle hydrogel consisting of silver nanoparticles.Irregular wound of rat has good adaptability, and under the action of electric stimulation, the healing process of rat infected wound has significant promoting effect, the hydrogel is high in safety, and is convenient to prepare.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a silver nanowire-reinforced injectable conductive particle hydrogel, its preparation method, and its application. Background Technology

[0002] Skin is one of the most important organs in the human body, playing a crucial role in protecting internal organs from external damage (such as injury and microbial infection). Due to prolonged direct contact with the complex external environment, skin is easily traumatized in daily life, forming wounds. Persistent wound infection can cause patients lasting pain and even permanent damage. In recent years, conductive hydrogels have proven to be an effective wound dressing, promoting wound healing by delivering electrical stimulation. Chinese invention patent CN202110761262.X discloses a method for preparing and applying a visualized antibacterial conductive dressing, developing an antibacterial conductive wound-healing hydrogel dressing using raw materials such as polyethylene glycol and borax; Chinese invention patent CN202111032557.X discloses a flexible conductive angiogenesis-promoting material and its preparation method, using acrylamide as the main component and preparing a flexible conductive angiogenesis-promoting dressing through chemical cross-linking agents and initiators. However, most of the patents currently filed for electrically stimulating hydrogel wound dressings are chemically cross-linked monolithic polymer hydrogels. Although they have high mechanical strength, they lack injectability, and the chemical cross-linking agents and initiators can introduce significant toxicity.

[0003] For electrically stimulating conductive hydrogel dressings, injectability is crucial to achieving the desired therapeutic effect for the following reasons: (1) it adapts well to the wound, enabling successful transmission of electrical signals to specific wound sites; (2) it leaves no residual space, preventing bacterial growth. Therefore, there is an urgent need to develop an injectable conductive hydrogel dressing that can adapt well to irregular wounds.

[0004] Particulate gels are typically formed from particulate micro / nanomaterials through physical or non-covalent interactions, exhibiting excellent biocompatibility, injectability, and adaptability to irregular wounds. However, physically cross-linked particulate gels inherently possess weak mechanical properties, limiting their application in everyday sports scenarios and hindering long-term wound closure. Enhancing the mechanical properties of hydrogels often involves increasing the degree of cross-linking, but this method can cause the hydrogel to lose its injectability. How to improve the mechanical properties of hydrogels without compromising their injectability is a pressing issue. One-dimensional inorganic nanomaterials possess rigid inorganic properties and stable network structures, which can significantly improve the mechanical properties of composite materials. Silver nanowires, in particular, with their excellent conductivity and mechanical flexibility, have become ideal assembly building blocks for stretchable flexible electronic devices. Simultaneously, nanosilver possesses long-lasting and broad-spectrum antibacterial properties.

[0005] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of this invention is to solve the problems that most existing conductive hydrogel dressings cannot adequately adapt to irregular wounds, resulting in poor treatment effects, and that physically cross-linked particulate gels have weak mechanical properties, cannot withstand external loads, and are difficult to seal wounds for a long time. The invention provides a silver nanowire-reinforced injectable conductive particulate hydrogel, its preparation method, and its application.

[0007] To achieve the above objectives, this invention discloses a method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel, comprising the following steps:

[0008] S1, gelatin nanoparticles and dopamine silver nanowires are mixed under alkaline conditions (pH≈12), where both types of particles have negative charges and can be fully and evenly mixed.

[0009] S2, Add the acidifying agent gluconate-δ-lactone powder (GDL, acidifying agent) to the mixed system obtained in step S1 to adjust the pH value of the system to be lower than the isoelectric point of gelatin (pH≤6). At this time, the gelatin nanoparticles change from negative charge to positive charge, while the dopamine silver nanowires remain negatively charged. Electrostatic interaction is generated between the two types of particles, and after gelation, an injectable conductive particle hydrogel reinforced with silver nanowires is obtained.

[0010] The preparation method of gelatin nanoparticles in step S1 includes the following steps:

[0011] S111: Gelatin is dissolved in deionized water by heating to obtain a gelatin solution. Acetone is then added, and the solution is allowed to stand at room temperature for 12 hours. The supernatant is removed, and the precipitate is dissolved again in deionized water and freeze-dried to obtain lyophilized high molecular weight gelatin.

[0012] S112, gelatin nanoparticles were prepared using a solvent removal method. The lyophilized gelatin obtained in step S111 was dissolved in deionized water, and the pH was adjusted to 2.5 with dilute hydrochloric acid. Acetone was added dropwise with stirring, and then glutaraldehyde solution was added to the gelatin dispersion at room temperature. The mixture was stirred in the dark for 16 hours, and then glycine aqueous solution was added to the gelatin dispersion. After stirring for 1 hour, the mixture was filtered, centrifuged, and washed to obtain amphoteric gelatin nanoparticles.

[0013] The preparation method of dopamine silver nanowires in step S1 includes the following steps:

[0014] S121, dissolve polyvinylpyrrolidone K30 in glycerol, then add sodium chloride aqueous solution and stir until homogeneous to obtain a mixed solution;

[0015] S122, silver nitrate is added to the mixed solution obtained in step S121, and the mixture is heated to react. After the reaction is completed, deionized water is added and the mixture is allowed to stand for one week. The supernatant is removed, and the precipitate is centrifuged and washed to obtain silver nanowires.

[0016] S123, silver nanowires were dispersed in Tris-HCl buffer solution at pH 8.5, and dopamine hydrochloride was added and stirred for 12 h. Under the self-polymerization effect of dopamine, the silver nanowires were coated with dopamine. After centrifugation and washing, dopamine-coated silver nanowires were obtained.

[0017] In step S122, the reaction temperature is increased from 25°C to 210°C over a period of 35 minutes.

[0018] In step S123, the mass ratio of silver nanowires to dopamine hydrochloride is 5:1.

[0019] In step S1, gelatin nanoparticles and dopamine silver nanowires are vortexed and mixed at pH≈12.

[0020] In step S1, the mass ratio of gelatin nanoparticles to dopamine silver nanowires is 1:1 to 4.

[0021] The solid content in the silver nanowire-reinforced injectable conductive particle hydrogel obtained in step S2 is 15–37.5 w / v.

[0022] The present invention also discloses the silver nanowire-reinforced injectable conductive particle hydrogel prepared by the above preparation method, and the application of such silver nanowire-reinforced injectable conductive particle hydrogel in promoting the healing of infected wounds by electrical stimulation.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The injectable conductive particle hydrogel prepared by this invention is assembled into a stable three-dimensional particle network by the controllable electrostatic uniform mixing of building blocks. It does not involve complex chemical cross-linking. The raw materials and cross-linking methods have good biocompatibility, which is beneficial to clinical translation.

[0025] 2. The injectable conductive particulate hydrogel prepared by this invention has superior mechanical and electrical properties. Particulate gels typically have weak mechanical properties, limiting their application in everyday sports scenarios. A common method to improve the mechanical properties of hydrogels is to use irreversible covalent bonds to increase their crosslinking degree, but this usually makes the hydrogel non-injectable. Therefore, the injectable conductive particulate hydrogel prepared by this invention improves the mechanical properties of particulate gels while maintaining their excellent injectability.

[0026] 3. The injectable conductive particle hydrogel prepared by this invention has good antibacterial and conductive properties. The antibacterial property can effectively prevent wound infection, and the conductive property can promote wound healing under electrical stimulation. Under the synergistic effect of antibacterial and conductive properties, electrical stimulation can accelerate the healing of infected wounds. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the preparation principle of the silver nanowire-reinforced conductive injectable particulate hydrogel of the present invention.

[0028] Figure 2 Scanning electron microscope image of freeze-dried gelatin nanoparticles;

[0029] Figure 3 Scanning electron microscope image of dopamine silver nanowires;

[0030] Figure 4 Fourier transform infrared spectra of dopamine and dopamine silver nanowires (a) and X-ray photoelectron spectra of silver nanowires and dopamine silver nanowires (b);

[0031] Figure 5 Bar graphs showing the potential of gelatin nanoparticles and silver dopamine nanoparticles at different pH values;

[0032] Figure 6 The images show the particle size variations of gelatin nanoparticles, dopamine silver nanowires, and both at pH 6–7.

[0033] Figure 7 Scanning electron microscope image of the internal structure of an injectable conductive particle hydrogel reinforced with silver nanowires;

[0034] Figure 8 Modulus versus frequency curves and modulus versus stress curves for injectable particulate hydrogels reinforced with silver nanowires of different building block ratios (a) and (b).

[0035] Figure 9 Viscosity versus shear rate curves of injectable particulate hydrogels reinforced with silver nanowires of different building block ratios;

[0036] Figure 10 Electrical conductivity of injectable particulate hydrogels enhanced with silver nanowires of different building block ratios;

[0037] Figure 11 A bar graph (a) and a digital photograph (b) of the injection process of a conductive particulate hydrogel reinforced with silver nanowires at a mass ratio of 1:3 (gelatin nanoparticles and dopamine silver nanowires).

[0038] Figure 12The average storage modulus (a) and average compressive modulus (b) of the silver nanoparticle conductive particle hydrogel and the silver nanowire-reinforced conductive particle hydrogel under frequency scanning.

[0039] Figure 13 Bar chart showing the average conductivity of silver nanoparticle conductive particle hydrogel and silver nanowire-reinforced conductive particle hydrogel.

[0040] Figure 14 Digital photographs showing the before and after states of the ability of silver nanoparticle conductive particle hydrogel and silver nanowire-reinforced conductive particle hydrogel to continuously seal wounds under simulated motion scenarios.

[0041] Figure 15 Digital photographs of the filling of an in vitro wound model with silver nanowire conductive chemically cross-linked monopolymer hydrogel and silver nanowire reinforced injectable conductive particle hydrogel.

[0042] Figure 16 Schematic diagram of in vivo adaptation of silver nanowire conductive chemically cross-linked monopolymer hydrogel (a) and silver nanowire reinforced injectable conductive particle hydrogel (b) to wound and H&E staining photograph of skin at the wound site.

[0043] Figure 17 Scanning image of a wound filled with a silver nanowire-reinforced injectable conductive particle hydrogel;

[0044] Figure 18 Digital photographs (a) and bar charts (b) showing the wound healing status of the control group, gel group, and electrical stimulation group on days 4, 8, and 12 after wound treatment;

[0045] Figure 19 H&E staining and Masson staining images of the wound site on days 4, 8, and 12 after wound treatment are shown for the control group, gel group, and electrical stimulation group. Detailed Implementation

[0046] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0047] Example 1

[0048] 1. Preparation of gelatin nanoparticles, the steps are as follows:

[0049] Spherical gelatin nanoparticles were prepared by a two-step solvent removal method.

[0050] (1) Dissolve 25g of gelatin in 500mL of deionized water at 50℃. Then, add 500mL of acetone to the gelatin solution, let the mixture stand at room temperature for 12 hours, remove the supernatant, dissolve the gelatin precipitate again in deionized water at 50℃, and freeze-dry to obtain high molecular weight gelatin;

[0051] (2) Dissolve 3.75 g of high molecular weight gelatin in 75 mL of deionized water, and then add dilute hydrochloric acid to adjust the pH of the solution to 2.5. While stirring at 1000 rpm, add 225 mL of acetone dropwise to the 40 °C gelatin solution using a syringe pump at a rate of 10 mL / min. After the reaction solution is cooled to room temperature, add 550 μL of glutaraldehyde solution (25 wt%), and stir at 600 rpm for 16 hours under light-protected conditions.

[0052] (3) Add 100 mL of 300 mM glycine aqueous solution to the gelatin dispersion prepared in step (2) to remove unreacted aldehyde groups. After stirring for 1 hour, filter the dispersion through a 100 μm sieve. Then, by centrifugation and washing, redisperse the precipitate in an acetone aqueous solution (volume ratio of acetone:water = 1:3) and freeze-dry for later use.

[0053] 2. Preparation of dopamine silver nanowires, the steps are as follows:

[0054] Silver nanowires prepared by polyol method

[0055] (1) Dissolve 5.86 g of polyvinylpyrrolidone K30 in 200 mL of glycerol at 60 °C, cool, and then add 1.58 g of silver nitrate and 0.5 mL of 0.12 mg / mL sodium chloride solution. Heat the mixture to 210 °C over 35 minutes with stirring at 50 rpm.

[0056] (2) After the reaction was completed, 300 mL of deionized water was added, and after standing for one week, the supernatant was removed. The precipitate was washed by centrifugation with deionized water to obtain silver nanowires.

[0057] (3) 0.5 g of silver nanowires were dispersed in 100 mL of 10 mM Tris-HCl buffer solution (pH = 8.5), and 0.1 g of dopamine hydrochloride was added. After stirring for 12 hours, the mixture was washed by centrifugation with deionized water to obtain dopamine silver nanowires.

[0058] 3. Preparation of silver nanowire-reinforced injectable conductive particle hydrogel, the steps are as follows:

[0059] like Figure 1As shown, a solution of gelatin nanoparticles with pH ≈ 12 and 150 mg / mL and a solution of dopamine silver nanowires with pH ≈ 12 and 150 mg / mL were prepared. 0.5 mL of each solution was taken and thoroughly mixed. Then, 14.25 mg of gluconate-δ-lactone was added to adjust the pH of the system to 6-7 to induce gelation, thus obtaining a silver nanowire-reinforced injectable conductive particle hydrogel with a mass ratio of gelatin nanoparticles to dopamine silver nanowires of 1:1.

[0060] Figure 2 This is a scanning electron microscope image of freeze-dried gelatin nanoparticles. Figure 3 This is a scanning electron microscope image of dopamine silver nanowires.

[0061] Figure 4 a is the Fourier transform infrared spectrum of dopamine and dopamine silver nanowires. Figure 4 b shows the X-ray photoelectron spectra of silver nanowires and dopamine silver nanowires, indicating that dopamine was successfully modified on the surface of silver nanowires.

[0062] Figure 5 The results show that gelatin nanoparticles and dopamine silver nanowires are charged with negative charge at pH > 8 and positive charge at pH < 8, while dopamine silver nanoparticles are always negatively charged at different pH values. The electrostatic force between particles is the theoretical basis for the formation of particulate hydrogels.

[0063] Figure 6 The figures show the particle size changes of gelatin nanoparticles, dopamine silver nanowires, and both at pH 6–7. The results indicate that gelatin nanoparticles and dopamine silver nanowires undergo electrostatic assembly under gelation pH conditions.

[0064] Figure 7 Scanning electron microscopy images of the internal structure of injectable conductive particle hydrogel reinforced with silver nanowires show that gelatin nanoparticles and dopamine silver nanowires are uniformly distributed within the gel, and the dopamine silver nanowires form a stable one-dimensional nanowire network structure.

[0065] Example 2

[0066] The difference between this embodiment and Example 1 is that the mass ratio of gelatin nanoparticles to dopamine silver nanowires is 1:2, while all other preparation conditions are the same. Specifically, a solution of gelatin nanoparticles at pH ≈ 12 and a solution of dopamine silver nanowires at pH ≈ 12 and a solution of dopamine silver nanowires at pH ≈ 12 are prepared. 0.5 mL of each solution is taken and thoroughly mixed. Then, 14.25 mg of gluconate-δ-lactone is added to adjust the pH of the system to 6-7 to induce gelation, thus obtaining a silver nanowire-reinforced injectable conductive particle hydrogel with a gelatin nanoparticle to dopamine silver nanowire mass ratio of 1:2.

[0067] Example 3

[0068] The difference between this embodiment and Example 1 is that the mass ratio of gelatin nanoparticles to dopamine silver nanowires is 1:3, and other preparation conditions are slightly different. Specifically, a gelatin nanoparticle solution with pH≈12 and a dopamine silver nanowire solution with pH≈12 and a dopamine silver nanowire solution with pH≈12 and a dopamine silver nanowire solution are prepared. 0.5 mL of the gelatin nanoparticle solution and 0.75 mL of the dopamine silver nanowire solution are thoroughly mixed and then freeze-dried. Then, 1 mL of a 17.81 mg / mL gluconate-δ-lactone solution is added to adjust the pH of the system to 6-7 to induce gelation, thus obtaining a silver nanowire-reinforced injectable conductive particle hydrogel with a gelatin nanoparticle to dopamine silver nanowire mass ratio of 1:3.

[0069] Example 4

[0070] The difference between this embodiment and Example 1 is that the mass ratio of gelatin nanoparticles to dopamine silver nanowires is 1:4, and other preparation conditions are slightly different. Specifically, a gelatin nanoparticle solution with pH ≈ 12 and a dopamine silver nanowire solution with pH ≈ 12 and a concentration of 150 mg / mL were prepared. 0.5 mL of the gelatin nanoparticle solution and 1 mL of the dopamine silver nanowire solution were thoroughly mixed and then freeze-dried. Then, 1 mL of a 21.38 mg / 1 mL gluconate-δ-lactone solution was added to adjust the pH of the system to 6-7, causing gelation. This yields a silver nanowire-reinforced injectable conductive particle hydrogel with a gelatin nanoparticle to dopamine silver nanowire mass ratio of 1:4.

[0071] Rheological comparisons were performed on the silver nanowire-reinforced injectable conductive particle hydrogels with different mass ratios obtained in Examples 1-4, and the results are as follows: Figure 8 As shown, the storage modulus of the injectable conductive particle hydrogel increases with increasing dopamine silver nanowire content. However, when the dopamine silver nanowire content increases to 1:4, the critical strain value decreases (~65%), and the hydrogel stability decreases. The results are as follows... Figure 9 As shown, all four types of particulate hydrogels exhibit shear-thinning characteristics, indicating that they are all injectable.

[0072] The conductivity of injectable conductive particle hydrogels reinforced with silver nanowires at different mass ratios obtained in Examples 1-4 was compared, and the results are as follows: Figure 10 As shown, the conductivity of the injectable conductive particle hydrogel increases with increasing dopamine silver nanowire content. However, when the dopamine silver nanowire content increases to 1:3, the conductivity of the conductive colloidal gel increases sharply.

[0073] Example 5

[0074] Based on mechanical and electrical properties, the injectable conductive particle hydrogel reinforced with silver nanowires in the preferred embodiment (mass ratio of gelatin nanoparticles to dopamine silver nanowires of 1:3) was studied in detail. The injection force was measured when injected using syringes with 19- and 21-G needles, and the injection speed was set to 20 mm / min.

[0075] Figure 11 The bar chart shows the average injection force during the stable injection force segment of the conductive particle hydrogel, along with digital photographs of the injection process. The results indicate that the conductive particle hydrogel exhibits good injection performance when injected with needles of different specifications.

[0076] Example 6

[0077] Based on the silver nanowire-reinforced injectable conductive particle hydrogel with a mass ratio of gelatin nanoparticles to dopamine silver nanowires of 1:3 as selected in Example 3, an injectable conductive particle hydrogel with a mass ratio of gelatin nanoparticles to dopamine silver nanoparticles of 1:3 was prepared as a control. The mechanical properties, electrical properties, and ability to continuously seal wounds in sports scenarios were compared between the two.

[0078] The difference between this embodiment and Embodiment 3 is that the assembly unit of the injectable conductive particle gel is replaced with dopamine silver nanoparticles, and other preparation conditions are slightly different.

[0079] 1. Preparation of dopamine silver nanoparticles, the steps are as follows:

[0080] Silver nanoparticles were prepared by the polyol method.

[0081] (1) Dissolve 5.86 g of polyvinylpyrrolidone K30 in 200 mL of glycerol at 60 °C. After cooling, add 1.58 g of silver nitrate and 0.5 mL of 0.12 mg / mL sodium chloride solution. Heat the mixture to 210 °C over 35 minutes with vigorous stirring at 700 rpm.

[0082] (2) After the reaction was completed, 300 mL of deionized water was added, and the silver nanoparticles were obtained by washing by centrifugation at 8000 rpm for 10 minutes with deionized water.

[0083] (3) 0.5 g of silver nanoparticles were dispersed in 100 mL of 10 mM Tris-HCl buffer solution (pH = 8.5), and 0.1 g of dopamine hydrochloride was added. After stirring for 12 hours, the mixture was washed by centrifugation with deionized water to obtain dopamine silver nanoparticles.

[0084] 2. Preparation of silver nanoparticle injectable conductive particle hydrogel, the steps are as follows:

[0085] Prepare a gelatin nanoparticle solution with pH ≈ 12 and a dopamine silver nanoparticle solution with pH ≈ 12 and a concentration of 150 mg / mL. Take 0.5 mL of the gelatin nanoparticle solution and 0.75 mL of the dopamine silver nanoparticle solution, mix them thoroughly, and freeze-dry. Then add 1 mL of 17.81 mg / mL gluconate-δ-lactone solution to adjust the pH of the system to 6-7 to induce gelation, thus obtaining a silver nanoparticle injectable conductive particle hydrogel with a mass ratio of gelatin nanoparticles to dopamine silver nanoparticles of 1:3.

[0086] Rheological tests were performed on two different injectable conductive particulate hydrogels. The hydrogels were filled into cylindrical molds (diameter: 8 mm, height: 10 mm), stabilized overnight in a 4°C refrigerator, and then demolded. The hydrogels were then compressed by 50% using a multi-material testing machine to compare their compression resistance. The two particulate hydrogels were also placed on pigskin and shaken for 10 minutes at 37°C and 300 rpm to simulate a motion scenario, comparing their ability to maintain wound closure under such conditions.

[0087] Figure 12 The table shows the bar charts for the average storage modulus and average compressive modulus of the two types of conductive particle hydrogels under frequency scanning. The results show that the storage modulus and compressive modulus of the silver nanowire-reinforced injectable conductive particle hydrogel are 7.5 times and 10.5 times that of the silver nanoparticle-reinforced injectable conductive particle hydrogel, respectively, which are significantly improved compared to the silver nanoparticle-reinforced injectable conductive particle hydrogel.

[0088] Figure 13 The bar chart shows the average conductivity of the two types of conductive particle hydrogels. The results indicate that the conductivity of the silver nanowire-reinforced injectable conductive particle hydrogel is 13 times that of the silver nanoparticle-reinforced injectable conductive particle hydrogel, which is significantly higher.

[0089] Figure 14 Digital photographs show the pre- and post-treatment wound closure capabilities of two types of conductive particle hydrogels under simulated motion scenarios. The results indicate that the silver nanoparticle-reinforced injectable conductive particle hydrogel leaks out during motion and fails to provide adequate wound closure; while the silver nanowire-reinforced injectable conductive particle hydrogel exhibits excellent wound closure capability under motion scenarios.

[0090] Example 7

[0091] Based on the silver nanowire-reinforced injectable conductive particle hydrogel with a preferred gelatin nanoparticle to dopamine silver nanowire mass ratio of 1:3 in Example 3, a silver nanowire conductive chemically crosslinked monopolymer hydrogel with a gelatin molecule to dopamine silver nanoparticle mass ratio of 1:3 was prepared as a control to compare the adaptability of the two to irregular wounds.

[0092] 1. Preparation of silver nanowire conductive chemically cross-linked monolithic polymer hydrogel, the steps are as follows:

[0093] Prepare a 300 mg / mL gelatin solution and a 300 mg / mL dopamine silver nanowire solution; mix 0.25 mL of gelatin solution and 0.75 mL of dopamine silver nanowire solution evenly, and then add 100 μL of glutaraldehyde solution (50 wt%) to chemically crosslink the hydrogel.

[0094] 2. Assessment of adaptability to irregular wounds

[0095] A sharp wound was created on the back of a shaved SD rat using a lancet. The wound was treated with a silver nanowire-reinforced injectable conductive particle hydrogel and a silver nanowire-conductive chemically crosslinked monolithic polymer hydrogel, respectively. Skin from the wound site was collected one day later for histological analysis.

[0096] Figure 15 Digital photographs showing the filling of in vitro wound models with silver nanowire-conductive chemically cross-linked monopolymer hydrogels and silver nanowire-reinforced injectable conductive particle hydrogels. Figure 16 Schematic diagram of injectable conductive particle hydrogel reinforced with silver nanowires and silver nanowire conductive chemically crosslinked monolithic polymer hydrogel adapted to wound, and H&E staining photograph of skin at the wound site. Figure 17 Scanning images of wound filling with silver nanowire-reinforced injectable conductive particle hydrogel. The results show that the silver nanowire-conductive chemically cross-linked monolithic polymer hydrogel cannot adequately adapt to the wound, while the silver nanowire-reinforced injectable conductive particle hydrogel can fill deep into the wound and adapt effectively.

[0097] Example 8

[0098] The effect of silver nanowire-reinforced injectable conductive particle hydrogel with a preferred gelatin nanoparticle-to-dopamine silver nanowire mass ratio of 1:3 in Example 3 on promoting the healing of infected wounds in rats under electrical stimulation was evaluated as follows:

[0099] SD rats were divided into three experimental groups, with 5 rats in each group (n=5). After anesthesia and shaving, a full-thickness circular wound with a diameter of 8 mm was created on the back of each rat. 100 μL of a suspension of drug-resistant Staphylococcus aureus was injected into the wound site. 7(CFU / mL) was applied evenly with a sterile swab for further treatment. The control group received no treatment. In the gel group, 100 μL of silver nanowire-reinforced injectable particle gel was evenly applied to the wound surface. In the electrical stimulation group, 100 μL of silver nanowire-reinforced injectable particle gel was evenly applied to the wound surface, and two copper electrodes were placed near the wound, applying a 50 mV DC current for 30 minutes daily. The conductive particle gel was replaced every two days. The remaining wound area was analyzed using ImageJ software. Skin samples were collected from the wound site on days 4, 8, and 12 post-treatment for histological analysis.

[0100] Figure 18 Digital photographs and bar graphs showing wound healing status and average healing rate on days 4, 8, and 12 after wound treatment for the three treatment groups are presented. The results showed that, due to the antibacterial activity of the dopamine silver nanowires, the healing rate of the gel group on day 12 (87.9%) was higher than that of the control group (75.5%). Under the synergistic effect of antibacterial and electrical stimulation, the healing rate of the electrical stimulation group reached as high as 98.7%, significantly higher than the other groups. Figure 19 H&E and Masson staining images of the wound site on days 4, 8, and 12 after wound treatment are shown for the three treatment groups. Results indicate that on day 4, newly formed epidermis and dense collagen fibers were clearly observed in the electrostimulation group; loose collagen fibers were also found in the gel group, but the basic epithelial and dermal structures were absent in the control group. Compared to the gel group, the electrostimulation group formed blood vessels and a thicker epidermis on day 8; while the dermis in the control group was incomplete and the collagen fibers were loose. On day 12, the electrostimulation group formed a thicker epithelial and dermal layer, numerous mature hair follicles, and orderly arranged dense collagen fibers; while although a complete epithelial structure was formed in the gel and control groups, numerous gaps remained between collagen fibers. Histologically, this further demonstrates that the silver nanowire-reinforced injectable conductive particle hydrogel promoted the healing of infected wounds in rats under electrostimulation. Furthermore, our gel was observed in the gel group on days 4 and 8, indicating excellent filling and retention properties at the wound site.

[0101] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel, characterized in that, Includes the following steps: S1, gelatin nanoparticles and dopamine silver nanowires are uniformly mixed under alkaline conditions; S2, add the acidifying agent gluconate-δ-lactone powder to the mixed system obtained in step S1, adjust the pH of the system to ≤6, and after gelation, obtain silver nanowire-reinforced injectable conductive particle hydrogel. In step S1, the mass ratio of gelatin nanoparticles to dopamine silver nanowires is 1:1~4.

2. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 1, characterized in that, The preparation method of gelatin nanoparticles in step S1 includes the following steps: S111: Gelatin is dissolved in deionized water by heating to obtain a gelatin solution. Acetone is then added, and the solution is allowed to stand at room temperature for 12 hours. The supernatant is removed, and the precipitate is dissolved again in deionized water and freeze-dried to obtain lyophilized high molecular weight gelatin. S112, dissolve the freeze-dried gelatin obtained in step S111 in deionized water, add dilute hydrochloric acid to adjust the pH to 2.5, add acetone dropwise while stirring, then add glutaraldehyde solution to the gelatin dispersion at room temperature, stir for 16 hours in the dark, then add glycine aqueous solution to the gelatin dispersion, stir for 1 hour, filter, centrifuge and wash to obtain amphoteric gelatin nanoparticles.

3. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 1, characterized in that, The preparation method of dopamine silver nanowires in step S1 includes the following steps: S121, dissolve polyvinylpyrrolidone K30 in glycerol, then add sodium chloride aqueous solution and stir until homogeneous to obtain a mixed solution; S122, silver nitrate is added to the mixed solution obtained in step S121, and the mixture is heated to react. After the reaction is completed, deionized water is added and the mixture is allowed to stand for one week. The supernatant is removed, and the precipitate is centrifuged and washed to obtain silver nanowires. S123, silver nanowires were dispersed in Tris-HCl buffer solution at pH 8.5, dopamine hydrochloride was added and stirred for 12 h, and then centrifuged and washed to obtain dopamine silver nanowires.

4. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 3, characterized in that, In step S122, the reaction temperature is increased from 25 °C to 210 °C over a period of 35 min.

5. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 3, characterized in that, In step S123, the mass ratio of silver nanowires to dopamine hydrochloride is 5:

1.

6. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 1, characterized in that, In step S1, gelatin nanoparticles and dopamine silver nanowires are vortexed and mixed at pH≈12.

7. The method for preparing a silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 1, characterized in that, The solid content in the silver nanowire-reinforced injectable conductive particle hydrogel obtained in step S2 is 15~37.5 w / v.

8. A silver nanowire-reinforced injectable conductive particle hydrogel prepared by the preparation method according to any one of claims 1 to 7.

9. The use of the silver nanowire-reinforced injectable conductive particle hydrogel as described in claim 8 in the preparation of an electrically stimulated drug for promoting the healing of infected wounds.

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