An antibacterial and cell proliferation-promoting hydrogel skin wound dressing and a preparation method thereof

Abstract

The application discloses an antibacterial and cell proliferation promoting hydrogel skin wound dressing and a preparation method, relates to the technical field of composite hydrogels, and comprises a composite hydrogel, wherein the composite hydrogel comprises surface modified BTO, a PEDOT:PSS suspension, cationic guar gum, deionized water and an acid-base regulator, and the surface modified BTO comprises BTO nanoparticles wrapped with PDA on the surface; the PPGS conductive composite hydrogel is arranged to further promote wound healing through micro-current stimulation formed by piezoelectric nanoparticle surface charges after inhibiting bacterial infection of a human body wound, becomes a new treatment method for skin wound infection treatment, and has better healing effect when applied to skin wound dressings.

Description

Technical Field

[0001] This invention relates to the field of composite hydrogel technology, specifically to an antibacterial and cell proliferation-promoting hydrogel skin wound dressing and its preparation method. Background Technology

[0002] As the largest organ in the human body, the skin plays a vital role in a series of physiological activities, including resisting external microorganisms, regulating body temperature, and maintaining homeostasis. Skin damage can lead to a range of problems such as persistent bleeding, bacterial infection, and inflammation, making skin wound management a focus of research.

[0003] Numerous wound dressings have been developed to address a range of issues related to skin wound healing. Among these, hydrogels, as 3D porous materials composed of physical or chemical cross-links, have garnered significant attention in the medical field. Hydrogels can provide a moist environment for wounds and inhibit the proliferation of anaerobic bacteria. To date, various hydrogels with hemostatic, antibacterial, and cell-proliferation properties have emerged. However, single-function hydrogels cannot meet the diverse needs of wound healing. Therefore, the demand for multifunctional hydrogels in the biomedical field is increasingly strong.

[0004] Conductive hydrogels have been shown to promote not only stem cell proliferation and differentiation and migration to negatively charged surfaces, but also neurite budding and neurite activating function, thus demonstrating potential for tissue repair and standing out among many functional hydrogels. The mechanical strength and modulus of hydrogels can be significantly altered by changing monomers and crosslinking agents, providing a good mechanical platform and suitable application forms for conductive polymers. The resulting conductive polymer hydrogels not only possess the excellent flexibility, biocompatibility, and self-healing capabilities of hydrogels, but also, through different preparation methods, can be synthesized into materials with various responsive properties such as photoelectric, thermoelectric, and electromagnetic properties, making them ideal for a wide range of applications.

[0005] Currently, the common application of conductive polymer hydrogels still requires the introduction of metal electrodes as electrical signal generators, which increases the risk of inflammation in the human body. Therefore, finding a biocompatible power source alternative is essential. Research has found that barium titanate (BTO) nanoparticles, as a typical piezoelectric catalytic material, generate a voltage between their two ends when impacted by mechanical waves. In the biomedical field, they are often used as acoustic sensitizers combined with ultrasound (US) to induce surface piezoelectric potentials. In addition, compared with traditional electrodes, BTO can also promote the interaction between polarized charges and charge carriers with H2O in the internal environment and O2 generated by tissue cavitation effects induced by US, thereby generating reactive oxygen species (ROS) through redox reactions. ROS can damage bacterial DNA, break peptide bonds, and disrupt biomembranes; furthermore, ROS can promote early necessary inflammation. This inflammatory state is conducive to promoting the secretion of angiogenesis-promoting cytokines by surrounding immune cells, helping to clear necrotic cells and form blood vessels, laying a good foundation for tissue repair. For example, it has been previously reported that a catechol-ZnO complex was introduced into a hyaluronic acid (HA) hydrogel platform, which can generate sufficient ROS spontaneously in bacterial-infected tissues.

[0006] However, there are various problems between organic conductive hydrogels and inorganic piezoelectric catalytic nanoparticles, such as modulus mismatch, easy particle aggregation, and low coupling efficiency. As a component similar to human melanin, PDA is often used to construct a biocompatible interface layer between organic and inorganic molecules. The hydroxyl groups (-OH) in PDA can crosslink with BTO nanoparticles to form a strong adhesion layer, and as a hydrophilic group, it enhances the hydrogen bonding between nanoparticles and water, thereby significantly improving the dispersibility of BTO in hydrogel systems and serving as an excellent bridge connecting nanoparticles and polymers.

[0007] To address the aforementioned issues, we provide an antibacterial hydrogel skin wound dressing that promotes cell proliferation and its preparation method, thereby resolving the problems mentioned above. Summary of the Invention

[0008] The purpose of this invention is to provide an antibacterial hydrogel skin wound dressing that promotes cell proliferation and its preparation method, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] An antibacterial and cell proliferation-promoting hydrogel skin wound dressing includes a composite hydrogel comprising surface-modified BTO, PEDOT:PSS suspension, cationic guar gum, deionized water, and a pH adjuster. The surface-modified BTO comprises BTO nanoparticles with PDA coated on their surface.

[0011] Another objective of this invention is to provide a method for preparing an antibacterial and cell-proliferation-promoting hydrogel skin wound dressing, specifically comprising the following steps:

[0012] Step 1: Add BTO to deionized water containing tromethorphan, apply ultrasound to form a uniform dispersion system, then add dopamine hydrochloride to the dispersion system and stir at room temperature for 24 hours.

[0013] Step 2: Separate the PDA@BTO particles from the solution stirred in Step 1 by centrifugation, wash with deionized water, and dry completely in an oven to obtain dried PDA@BTO particles;

[0014] Step 3: The dried PDA@BTO particles from Step 2 are ground to obtain nanoscale PDA@BTO nanoparticles, thus completing the surface modification of BTO;

[0015] Step 4: Disperse the PDA@BTO nanoparticles from Step 3 uniformly into a deionized water system, add PEDOT:PSS suspension and cationic guar gum, adjust the pH value with acetic acid, continue stirring for 10 seconds until the solution becomes homogeneous, and then add NaOH solution to adjust the pH value to obtain the composite hydrogel.

[0016] As a further aspect of the present invention: in step three, the dried PDA@BTO particles are ground using an agate mortar and pestle.

[0017] As a further aspect of the present invention:

[0018] In step one: the mass of BTO is 100mg, the mass of tromethamine is 25mg, and the mass of dopamine hydrochloride is 120mg;

[0019] In step four: the mass of PDA@BTO nanoparticles is 20 mg, the volume of the deionized water system is 1 mL, the volume of PEDOT:PSS suspension includes 0 μL, 30 μL, 50 μL or 100 μL of 1.5 wt%, the mass of cationic guar gum is 50 mg, the pH value is adjusted with 1 wt% acetic acid, and the pH value is adjusted with 10 μL of 0.2M NaOH solution.

[0020] As a further embodiment of the present invention: the drying temperature of the oven in step two is 60°C.

[0021] As a further aspect of the present invention: the washing process in step two shall be no less than three times.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention designs a PEDOT:PSS conductive composite hydrogel based on PDA-coated BTO nanoparticles. The PDA-modified layer can improve stress transmission capability and coordinate the modulus mismatch between inorganic nanofillers and organic polymer matrix. Compared with the unmodified version, it achieves simultaneous improvement in piezoelectric efficiency and piezoelectric coefficient. Through ultrasonic power testing, the PEDOT:PSS conductive composite hydrogel designed in this invention can further promote wound healing by stimulating microcurrents formed by surface charges of piezoelectric nanoparticles after inhibiting bacterial infection of human wounds. This becomes a new treatment method for skin wound infection and has better healing effect when applied to skin wound dressings.

[0024] 2. The synergistic enhancement effect of PDA@BTO nanoparticles on the conductivity of PEDOT:PSS hydrogel (PPGS) provided in this invention.

[0025] 3. This invention demonstrates the effects of microcurrent on bacterial elimination, cell proliferation, and tissue repair by preparing a non-conductive guar gum composite hydrogel (GSCH). Attached Figure Description

[0026] Figure 1 The SEM and zeta potentials of BTO and PDA@BTO are given.

[0027] Figure 2 (a) Zeta potential of BTO and PDA@BTO; (b) Transient photocurrent measurement in 0.1M Na2SO4 under US irradiation; (c) Degradation of Rhodamine B in different nanoparticle solution systems; (df) Acoustic degradation of RhB over time: (d) BTO, (e) PDA@BTO, (f) PPGSCH.

[0028] Figure 3 EPR spectrum (reaction conditions: [BP / MoS2]0 = 0.2 g / L, [DMPO]0 = 20 mM and [TEMP]0 = 20 mM).

[0029] Figure 4 SEM image and infrared spectrum of (ad)PPGSCH.

[0030] Figure 5 Figures showing the rheological properties and self-healing performance of PPGSCH: (ah) G′ and G″ of PPGSCH when the hydrogel rheological strain changes from 1% to 200%; (ij) Effect of PEDOT:PSS content and nanoparticle content on the gel point of PPGSCH; (kl) Rheological properties of the hydrogel when the alternating strain changes from 1% to 100%.

[0031] Figure 6(a) Conceptual diagram of PPGSCH conductivity; (b) PPGSCH conductivity test with gradient contents of PEDOT:PSS and PDA@BTO nanoparticles; (c) Real-time electro-healing measurements over three cutting and healing cycles.

[0032] Figure 7 The purpose was to (a) compare the CFU of Escherichia coli and Staphylococcus aureus after different treatments; (b) compare the bacterial survival rates of Escherichia coli and Staphylococcus aureus after different treatments; and (c) compare the bacterial survival rates of Escherichia coli and Staphylococcus aureus after 0-5 minutes of ultrasonic irradiation.

[0033] Figure 8 (a) Representative fluorescence images of 3T3 calcein am staining after 16 h of different treatments, scale bar: 50 μm; (b) Cell viability after 24 h of incubation with 3T3 at different concentrations (1–5 mg / mL) of PPGSCH; (c) 3T3 cell viability after different treatments.

[0034] Figure 9 (a) Changes in a mouse skin wound infection model after different treatments from 0 to 9 days; (b) H&E tissue staining. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] An antibacterial and cell proliferation-promoting hydrogel skin wound dressing includes a composite hydrogel comprising surface-modified BTO, PEDOT:PSS suspension, cationic guar gum, deionized water, and a pH adjuster. The surface-modified BTO comprises BTO nanoparticles with PDA coated on their surface.

[0038] A method for preparing an antibacterial and cell-proliferation-promoting hydrogel skin wound dressing, specifically including the following steps:

[0039] Step 1: Add BTO to deionized water containing tromethorphan, apply ultrasound to form a uniform dispersion system, then add dopamine hydrochloride to the dispersion system and stir at room temperature for 24 hours.

[0040] Step 2: Separate the PDA@BTO particles from the solution stirred in Step 1 by centrifugation, wash with deionized water, and dry completely in an oven to obtain dried PDA@BTO particles;

[0041] Step 3: The dried PDA@BTO particles from Step 2 are ground to obtain nanoscale PDA@BTO nanoparticles, thus completing the surface modification of BTO;

[0042] Step 4: Disperse the PDA@BTO nanoparticles from Step 3 uniformly into a deionized water system, add PEDOT:PSS suspension and cationic guar gum, adjust the pH value with acetic acid, continue stirring for 10 seconds until the solution becomes homogeneous, and then add NaOH solution to adjust the pH value to obtain the composite hydrogel.

[0043] Example 2

[0044] The difference from Example 1 is:

[0045] A method for preparing an antibacterial and cell-proliferation-promoting hydrogel skin wound dressing, specifically including the following steps:

[0046] Step 1: Surface modification of BTO:

[0047] 100 mg BTO was added to 20 mL of deionized water containing 25 mg tromethamine (Tris), and sonicated for 30 min to form a uniform dispersion. Then, 120 mg of dopamine hydrochloride (DA·HCl) was added to the system, and the mixture was stirred at room temperature for 24 h. PDA@BTO nanoparticles were separated by centrifugation, washed three times with deionized water, completely dried in a 60 °C oven, and finally ground with an agate mortar to obtain nanoscale PDA@BTO particles.

[0048] Step 2: Preparation of PEDOT:PSS conductive composite hydrogel:

[0049] 20 mg of PDA@BTO nanoparticles were uniformly dispersed in 1 mL of deionized water. 0 μL, 30 μL, 50 μL, and 100 μL of 1.5 wt% PEDOT:PSS suspension and 50 mg of cationic guar gum were added. To ensure a consistent pH, 1 wt% acetic acid was used to adjust the pH to xx. After stirring for 10 seconds, the solution became homogeneous. Then, 10 μL of 0.2 M NaOH solution was added to adjust the pH, thus obtaining the composite hydrogel.

[0050] Various experimental studies were conducted on the composite hydrogel in Example 2 above:

[0051] 1. Regarding the piezoelectric catalytic performance of PDA@BTO:

[0052] The morphology and crystal structure of BTO and PDA@BTO samples were investigated using scanning electron microscopy (SEM, Aztec X-Max80) and high-resolution transmission electron microscopy (HRTEM, JEM-2100Plus). The degree of dye degradation was measured using a Shimadzu UV3600 ultraviolet spectrophotometer. The ability of BTO and PDA@BTO samples to generate transient currents due to the piezoelectric effect was detected using a three-electrode system. Electron spin resonance spectroscopy (EPR, Bruker EMX+) was used to compare the generation and concentration of various active free radicals in BTO and PDA@BTO samples under ultrasonic conditions. SEM and TEM were performed at the Analytical and Testing Center of Sichuan University. Piezoelectric current experiments were conducted on an electrochemical workstation (CHi600e).

[0053] 2. Conductive properties of PEDOT: PSS composite hydrogel:

[0054] The structure of the composite hydrogel was observed using scanning electron microscopy (SEM, Aztec X-Max80). The mechanical stability and self-healing properties of the composite hydrogel were examined using a diffraction line resonator (DSR, R / S-CPS). Differences in electrical conductivity among the composite hydrogels were detected using a four-probe analyzer. The doping of PEDOT:PSS in the hydrogel was detected using Fourier transform infrared spectroscopy (FTIR, nano-FTIR).

[0055] 3. Biobehavior of conductive PEDOT:PSS composite hydrogels

[0056] 3.1 Bacterial Experiment

[0057] E. coli (G-) and B. pumilus (G+) were cultured in LB medium. Using E. coli and B. pumilus as models, the antibacterial activity of the composite hydrogel was studied. Bacterial suspensions were treated with US(-), US(+), GS, US(+)GS, PPGS, and US(+)PPGS, respectively. The antibacterial activity against Escherichia coli and Staphylococcus aureus was determined by colony counting. In a typical experiment, 250 μL of swollen PPGS was mixed with 250 μL of a bacterial suspension (1×10⁻⁶). 6 The mixture (CFU / mL) was subjected to US irradiation (1.5 W / cm²). 2 After 5 minutes, the mixture was incubated for a total of 6 hours in a shaker at 37°C. Finally, the supernatant was spread onto a plate and placed back into the shaker at 37°C for 12 hours. The colony viability on the plate was calculated using the following formula:

[0058]

[0059] 3.2 Cell Experiments

[0060] First, mouse fibroblasts (3T3) were cultured in DMEM medium in a constant temperature incubator at 37°C and 5% CO2. Dehydrated and sterilized GS and PPGS gels were then immersed in 2 mL of PBS buffer. After the cells reached the logarithmic growth phase, they were passaged at 2 × 10⁶ cells per well. 5 Cells were seeded at a density of 100 cells per well in 6-well cell culture plates and co-cultured with the swollen gel for 12 hours. The cytotoxicity of the hydrogel was then observed using the MTT assay.

[0061] After cell adhesion, the cells were subjected to a 5-minute UV test and then incubated at 37°C for 24 hours. The absorbance of the solution was measured at 450 nm using a microplate reader. Three replicates were performed for each group (n=3).

[0062] Subsequently, dead cells were stained to observe cell growth and survival. The specific procedure was as follows: the culture medium in the well plate was removed, the cells were washed three times with PBS solution and the supernatant was removed; calcium chlorophyll (AM 500μL, 2μM) and propidium iodide (PI 500μL, 8μM) were added to the wells respectively, and the cells were incubated at room temperature in the dark for 40 min; finally, the staining solution was removed to stop the incubation, the slides were mounted, and the cells were observed under a fluorescence microscope.

[0063] 3.3 Animal Experiments

[0064] Two identical 1cm incisions were made in the skin on the back of the anesthetized mouse. 2 Skin wounds were infected with E. coli. Mice were randomly divided into six groups: control, US, GS, GS+US, PPGS, and PPGS+US. In the GS, GS+US, PPGS, and PPGS+US groups, a GS and PPGS composite hydrogel was applied to the wound area at a dose of 1.5 mg / mL; in the US, GS+US, and PPGS+US groups, US was applied to the mice for 5 minutes daily. The control group received PBS treatment concurrently. Wound conditions were recorded on days 0, 2, 4, 6, and 9, and all mice were sacrificed on day 9. The wound area was completely removed, and the defect area (%) was calculated as A. t / A0×100%(A) t A0 is the initial wound area (where A0 is the area of ​​the wound after treatment). The wound tissue was stained with H&E and Masson staining and observed under a microscope.

[0065] 4. Results and Discussion

[0066] 4.1 Modification and Characterization of BTO Nanoparticles

[0067] 4.1.1 Sample Surface Morphology

[0068] like Figure 1As shown in Fig 2.af, BTO and PDA@BTO exhibit differences in surface morphology and particle size distribution. The surface of PDA@BTO is smoother than that of BTO, which reduces BTO aggregation to some extent. A black PDA coating with a thickness of approximately 10 nm is uniformly coated on the surface of the BTO nanoparticles. Light scattering analysis (DLS) of the zeta potential of BTO and PDA@BTO at the same concentration in an aqueous system shows that the zeta potential of PDA@BTO is approximately 7.65 times that of BTO. This may be because the PDA molecular chain has hydrophilic hydroxyl side groups, thus giving PDA@BTO better dispersibility in both aqueous and hydrogel systems, resulting in superior piezoelectric efficiency and piezoelectric coefficient.

[0069] 4.1.2 Analysis of differences in piezoelectric catalytic performance of samples

[0070] Traditional dye degradation experiments assess the performance of piezoelectric catalysis by utilizing reactive oxygen species (ROS) generated by piezoelectric nanoparticles to break down dye molecules into smaller molecules. Therefore, we designed a Rhodamine B degradation experiment to determine the presence of ROS in the system and to roughly compare the free radical generation effects of BTO and PDA@BTO in an aqueous system. First, when studying the adsorption of dyes by nanoparticles in a dark environment, we found that BTO and PDA@BTO particles exhibited some adsorption of dyes (not exceeding 10%) without the application of ultrasound. This may be due to the relatively rough surface of BTO particles, which allows for the physical adsorption of dye molecules; and the negative charge on the surface attracting a small number of dye molecules. The PDA coating, due to its abundant active groups on its surface structure, showed a slightly greater adsorption capacity for dyes than pure BTO.

[0071] like Figure 2 As shown, the two particle samples were thoroughly mixed in a 10 mg / L Rhodamine B solution and subjected to adsorption for 20 min before being sonicated. The normalized absorption intensity at 551 nm was then compared using a UV-Vis spectrophotometer. Figure 2 c shows that, at the same particle concentration, BTO requires 90 minutes to degrade the dye to 7%, after which the absorbance of the system does not change significantly with increasing ultrasonic time. In contrast, PDA@BTO degrades the dye to below 1% in about 40 minutes. Figure 2 f proves that the gel does not significantly weaken the piezoelectric catalytic effect of the nanoparticles.

[0072] To further demonstrate the superior piezoelectric effect of PDA@BTO, electron spin resonance spectroscopy (EPR) was used to quantitatively compare the concentrations of various active free radicals on the BTO surface before and after ultrasonic modification. Using 5,5-dimethyl-1-pyridine-N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP) as spin trapping agents, the concentrations of ·OH radicals were detected. - and O2- Signal. EPR results under 150W and 300W ultrasound are as follows: Figure 3 As shown, under ultrasonic irradiation, characteristic signals of quadruple DMPO and hexaple TEMP, i.e., strong hydroxyl radical and superoxide ion electrical signals, were found in both the BTO and PDA@BTO systems, with a g-factor value of ~2.034. Notably, the EPR spectrum of PDA@BTO showed a stronger signal than that of the BTO sample, and the characteristic signal increased with increasing ultrasonic power. Therefore, this study selected PDA@BTO to be composited with conductive hydrogel.

[0073] 4.2 PDA@BTO-doped PEDOT: PSS conductive hydrogel

[0074] 4.2.1 Surface morphology of composite hydrogel

[0075] To investigate the influencing factors on the physicochemical properties of PEDOT:PSS conductive hydrogel, the morphology of the hydrogel doped with PDA@BTO nanoparticles was characterized using scanning electron microscopy (SEM). Figure 4 It can be clearly seen that PPGS contains a large number of pores with a size greater than 5μm, while PDA@BTO nanoparticles are far from enough to fill the interior of PPGS. Therefore, it can be assumed that the addition of nanoparticles has little effect on the original swelling degree, water absorption, etc. of PPGS.

[0076] 4.2.2 Chemical structure of composite hydrogels

[0077] Generally, molecular forces such as hydrogen bonds and conjugation lead to a decrease in characteristic peak frequency and an increase in wavelength, resulting in a red shift of the characteristic peak; while the introduction of some polar groups may produce an inductive effect, resulting in a blue shift of the characteristic peak. (From infrared spectra...) Figure 3-8 It can be seen that the characteristic peak wavelength of OH in GS is 3387 cm⁻¹. -1 However, in PPGS, the characteristic peak shows a blue shift, with the wavelength changing to 3435 cm⁻¹. -1 This may be because the introduction of the PEDOT:PSS molecular chain disrupts the regular structure of guar gum, affecting some intermolecular hydrogen bonds. 2920cm -1 The characteristic peak at 1519 cm⁻¹ reflects the asymmetric CH stretching vibrations caused by the hydration of GS and PPGS hydrogels; -1 and 1473cm -1 The characteristic peaks at 1049 cm⁻¹ belong to the C=C of thiophene and benzene rings in PEDOT:PSS, respectively. -1 The characteristic peaks at this location belong to OSO in the PSS sulfonic acid group. The appearance and changes of these peaks are sufficient to prove that PEDOT:PSS has been successfully doped into CG to form PPGS.

[0078] 4.2.3 Rheological behavior of composite hydrogels

[0079] Furthermore, rheological testing characterized the mechanical strength and self-healing properties of PPGS. The experiment first used dynamic mechanical analysis to generate storage modulus / loss modulus-strain diagrams to determine the gel point (critical point) of PPGS prepared with different PEDOT:PSS doping levels, i.e., the intersection of storage modulus and loss modulus. Figure 5 (Chinese map ah). Figure 5 Figures i and j show that PPGS itself possesses good mechanical strength and dimensional stability. With increasing PEDOT:PSS content, the modulus of PPGS does not change significantly, but the strain gel point shows an increasing trend, indicating that the hydrogel's self-healing ability gradually strengthens. This may be because in PPGS, the main storage modulus comes from the abundant intermolecular hydrogen bonds in the cationic guar gum molecular chain. Furthermore, the positively charged quaternary ammonium cation groups in the guar gum molecule can interact with the negatively charged sulfonate anions in the PEDOT:PSS molecule to form ionic bonds with low kinetic activation energy, making them easier to recover after being broken. However, the specific kinetic reasons have not yet been determined. Meanwhile, experiments showed that the addition of BTO had no significant effect on the modulus and stability of PPGS, confirming that the size of the BTO nanoparticles and the interaction forces between the PDA surface and the hydrogel are insufficient to affect GS. After determining the gel point, thixotropic tests were performed using large strain (C = 100%) and small strain (C = 1%). Under small strain, the storage modulus was much greater than the loss modulus, indicating that the system was in a gel state. Under large strain, due to the shear thinning effect, the storage modulus decreased and became slightly less than the loss modulus, thus disrupting the gel state. Both before and after the strain recovery process, the modulus returned to its original state, further demonstrating the excellent self-healing properties of PPGS.

[0080] 4.2.4 Conductivity of Composite Hydrogels

[0081] To explore the effects of PEDOT:PSS doping concentration and PDA@BTO nanoparticles on the conductivity of PPGS, the conductivity of PPGS was measured using the four-probe method. PEDOT, due to its unique macrocyclic structure, is a common conductive polymer, while PSS is an effective water-soluble dopant that enhances the conductivity of PEDOT. The two form a stable zipper-like structure due to electrostatic interactions (PEDOT+ and PSS-), exhibiting a random coil morphology in solution. The PEDOT:PSS suspension doping concentration showed a positive linear correlation with the conductivity of PPGS; the reason for this was analyzed. BTO significantly enhanced the conductivity of PPGS, possibly because BTO has a high dielectric constant (1200 kHz), which can shield the Coulomb forces between PEDOT+ and PSS-, causing phase separation of PSS- and extending and orienting the random coil-like molecular chains, thereby improving conductivity.

[0082] To reveal the electro-self-healing behavior of the conductive hydrogel, cutting and repair tests were conducted. Once the hydrogel was cut into two pieces, its resistance was infinite in the open-circuit state. When the separated parts rejoined, the dynamic links at the damaged interface spontaneously re-established, thus restoring the circuit. Figure 6 As shown, the resistance exhibits relatively repetitive changes over three cycles, indicating that the PPGS composite hydrogel possesses repeatable and highly efficient electro-self-healing properties.

[0083] ROS also effectively penetrates the porous structure of the hydrogel. As mentioned earlier, ROS, as a strong oxidant, can disrupt the cell membranes and cell walls of pathogens such as bacteria, while also reacting with essential macromolecules within bacteria (such as RNA and DNA), thus preventing the emergence of drug-resistant bacteria. Finally, analysis of the PPGS+US group revealed a bacterial mortality rate of 90%, indicating that...

[0084] 4.3 In vitro antibacterial test

[0085] To address bacterial inflammation of skin wounds, the antibacterial properties and mechanism of PPGS were tested. This study first investigated the antibacterial performance of the composite hydrogel under an external field using the plating method, and observed bacterial growth morphology through live and dead cell staining. The groups were: blank group, US group, GS group, GS+US group, PPGS group, and PPGS+US group. Compared to the control group, the bacterial colony count was slightly lower under US irradiation alone, possibly due to the small amount of ROS generated by ultrasound cavitation, which exerts a weak antibacterial effect. Without US irradiation, the bacterial mortality rates in the GS and PPGS groups were similar, with a 60% survival rate for *E. coli*. This is attributed to the high quaternary ammonium salt content in guar gum, which disrupts the bacterial cell wall. For the GS+US group, a significant reduction in bacteria was observed compared to the GS and control groups. This is because BTO nanoparticles with excellent piezoelectric catalytic activity can generate ROS under ultrasound. Furthermore, the electric field polarization in the conductive PPGS leads to even more ROS generation, thus achieving a further antibacterial effect.

[0086] 4.4 In vitro cell proliferation of PPGS composite hydrogel

[0087] The biosafety and cell proliferation behavior of PPGS composite hydrogels under external field were assessed using optical density (OD) and live / dead staining. Figure 8 As shown, with the gradual increase of hydrogel concentration, the relative cell viability was greater than 85% after 24 hours of co-incubation with PPGS composite hydrogel and 3T3, indicating that the hydrogel, while possessing antibacterial properties, did not pose a threat to cells. To achieve good cell proliferation results, a hydrogel with a concentration of 3 mg / mL was finally used in the cell proliferation experiment.

[0088] Figure 9 The study demonstrated the effect of hydrogels on cell proliferation under external field conditions: compared to the blank control group, the GS+US group showed significant cell proliferation, with a survival rate of approximately 142% of the blank group. This may be because a small amount of ROS promotes cell proliferation. The PPGS+US group showed the highest cell proliferation, with a survival rate of approximately 192% of the blank group, and the cells exhibited an aggregated morphology around the hydrogel. This proves that in addition to a small amount of ROS, microcurrents also contribute significantly to cell proliferation.

[0089] Next, we used a mouse model to systematically evaluate the epidermal wound healing on the PPGS composite hydrogel. It is worth noting that, because different ultrasound powers were used in the antibacterial and cell proliferation experiments, we treated the mouse skin with ultrasound at different power levels at different time points based on the wound healing progress: 1.5 W / cm² was applied from day 0 to day 2. 2 (Consistent with the power in the antibacterial experiment), the ultrasonic power applied from day 4 to 9 was 0.5 W / cm². 2 (Consistent with the power of cell proliferation experiments) The aim is to first eliminate the inflammatory response caused by E. coli, and then promote the formation of skin tissue cells and new blood vessels. For example... Figure 9 As shown, the hydrogel treatment groups (GS, GS+US, PPGS, PPGS+US) performed significantly better than the blank group and the US group on days 4, 6, and 9. Among all groups, the PPGS+US group showed the greatest reduction in wound area and the least noticeable scarring, demonstrating the excellent skin regeneration ability of PPGS composite hydrogel.

[0090] To further verify the recovery of the healed skin tissue, H&E staining was used for further histological analysis. Figure 9 As shown, the skin surfaces of the blank group and the US group were irregular, with inflammatory cell infiltration and slight bleeding, and some red blood cells were expelled. The skin tissue of the hydrogel-treated group was more intact, with slight epidermal thickening and more epithelial tissue and collagen fibers. Among them, the PPGS+US group had more new capillary formation and the largest number of dermal skin appendages, indicating that the PPGS composite hydrogel has a good ability to promote tissue healing.

[0091] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Although this specification describes embodiments, not every embodiment contains only one technical solution. This method of description is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An antibacterial, cell-proliferation-promoting hydrogel skin wound dressing, comprising a composite hydrogel, characterized in that: The composite hydrogel comprises surface-modified BTO, PEDOT:PSS suspension, cationic guar gum, deionized water and acid-base regulator, wherein the surface-modified BTO comprises BTO nanoparticles with PDA coated on the surface. A method for preparing an antibacterial and cell-proliferation-promoting hydrogel skin wound dressing, specifically including the following steps: Step 1: Add BTO to deionized water containing tromethorphan, apply ultrasound to form a uniform dispersion system, then add dopamine hydrochloride to the dispersion system and stir at room temperature for 24 hours. Step 2: Separate the PDA@BTO particles from the solution stirred in Step 1 by centrifugation, wash with deionized water, and dry completely in an oven to obtain dried PDA@BTO particles; Step 3: The dried PDA@BTO particles from Step 2 are ground to obtain nanoscale PDA@BTO nanoparticles, thus completing the surface modification of BTO; Step 4: Disperse the PDA@BTO nanoparticles from Step 3 uniformly into a deionized water system, add PEDOT:PSS suspension and cationic guar gum, adjust the pH value with acetic acid, continue stirring for 10 seconds until the solution becomes uniform, and then add NaOH solution to adjust the pH value to obtain the composite hydrogel. In step one: the mass of BTO is 100 mg, the mass of tromethorphan is 25 mg, and the mass of dopamine hydrochloride is 120 mg; in step four: the mass of PDA@BTO nanoparticles is 20 mg, the volume of the deionized water system is 1 mL, the volume of the PEDOT:PSS suspension includes 0 μL, 30 μL, 50 μL or 100 μL of 1.5 wt%, the mass of cationic guar gum is 50 mg, the pH value is adjusted with 1 wt% acetic acid, and the pH value is adjusted with 10 μL of 0.2M NaOH solution.

2. The method for preparing an antibacterial, cell-proliferation-promoting hydrogel skin wound dressing according to claim 1, characterized in that, In step three, the dried PDA@BTO particles are ground using an agate mortar and pestle.

3. The method for preparing an antibacterial, cell-proliferation-promoting hydrogel skin wound dressing according to claim 1, characterized in that, In step two, the oven drying temperature is 60℃.

4. The method for preparing an antibacterial, cell-proliferation-promoting hydrogel skin wound dressing according to claim 1, characterized in that, The washing process in step two shall be no less than three times.

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