Rapid and Eco‐Friendly Preparation of Antibacterial Gauze by Alkali‐Acid Redeposition of Quercetin on Gauze Fiber and Subsequent Ultraviolet‐Assisted Reduction of Silver In Situ

Rapid and eco‐friendly preparation of biomedical materials is significant for practical applications. This study proposes a simple two‐step method for preparing silver nanoparticles (AgNPs)‐functionalized gauze dressings (Ag‐Q‐G) with antibacterial activity in a green and time‐efficient manner that requires <10 min. A smooth and uniform quercetin coating is formed on the gauze fibers using alkali–acid redeposition for 10 s. Subsequently, AgNPs are rapidly formed (in 5 min) and firmly deposited on the quercetin‐coated gauze by ultraviolet irradiation in an AgNO3 solution. The in vitro results indicate that Ag–Q–G exhibits excellent antibacterial activity, with a rate of 99.57% ± 0.52% against Staphylococcus aureus and 95.59% ± 1.50% against Escherichia coli, while maintaining acceptable cytocompatibility. An animal study reveals that Ag‐Q‐G reduces infection and promotes wound healing in a rat dorsal total cortical wound model. This approach provides a practical option for the commercial production of antibacterial gauze dressings.


Introduction
Wound infections are among the most prevalent complications encountered in clinical care. Dressings play a crucial role in wound treatment by protecting the wound, preventing infection, absorbing exudates, and eliminating necrotic tissues to facilitate wound healing. [1] The antimicrobial gauze dressings loaded with antibiotics have demonstrated therapeutic effects DOI: 10.1002/admi.202300257 against acute and severe skin damage. However, the repeated and long-term use of antibiotics may cause side effects such as drug resistance and allergy. [2] Thus, several modified gauzes based on non-antibiotic antimicrobials such as chitosan, [3,4] plant polyphenols, [5] reactive metal borides, [6] and antimicrobial peptides [7] have been developed. These antimicrobial agents and strategies demonstrate the advantages of low cytotoxicity and high safety. However, insufficient antibacterial activity and poor stability limit their application. [8] By contrast, antimicrobial metal ions (such as silver ions) possess higher antimicrobial activity and stability, a wider antimicrobial spectrum, and a lower risk of resistance. [9,10] A common method for preparing nanosilver on the surface of medical devices is the in situ chemical reduction of silver in the solution. [11] Recently, the use of plant phenols as reducing agents to produce nanosilver has attracted attention owing to their low cost, biological safety, and eco-friendly nature. [12,13] A typical process involves first building a plant-phenol coating and then forming silver nanoparticles (AgNPs) via the reduction of silver ions. [14] However, this method is time consuming and requires additional oxidizing agents or catalysts. To increase the production efficiency of AgNPs on the surface in a green manner, both plant-phenol coating and silver reduction methods should be improved. However, most reported plant-phenol coating strategies are based on the oxidative polymerization of plant phenols, which usually requires tens of minutes to hours. [15,16] Further, it has been reported that the rate of AgNPs generation via reduction can be accelerated by techniques such as heating, microwave irradiation, and ultraviolet radiation. [17,18] Among them, ultraviolet treatment exhibits notable advantages, such as low equipment demand and negligible impact on the substrate.
In this study, a water-insoluble plant flavonol and a polyphenol compound, quercetin, were used to rapidly build a plant-phenol coating. Because of the hydrogen-bonded network in its crystal structure, quercetin is practically insoluble under neutral conditions. However, it is soluble in aqueous alkaline solutions because hydrogen bonding is very sensitive to alkali but remains stable in acidic conditions. [19,20] This feature makes the quercetin readily soluble in an alkaline aqueous solution; thereafter, it can be precipitated in an acidic condition, as shown in Figure 1A. By utilizing this property, the quercetin coating on gauze fibers was achieved within a few seconds by infiltrating the gauze in a specific quercetin alkaline solution and then rapidly transferring it into an acidic solution ( Figure 1B). The resulting quercetin coating possessed numerous phenolic hydroxyl groups, which could act as electron donors to reduce silver ions. [21] Moreover, Ultraviolet (UV) irradiation was used to promote the in situ generation of AgNPs on the quercetin coating ( Figure 1B), which considerably reduced the preparation time.
The morphology and elemental distribution of the samples were characterized using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), respectively. The total amount of quercetin on the gauze was determined by UV-vis spectroscopy after lye elution, and the total amount of silver and its elution behavior in PBS were determined using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Finally, the antibacterial efficacy and cytocompatibility of the AgNPcoated gauze were evaluated, and a rat model with Staphylococcus aureus (S. aureus) wound infection was used to evaluate its antiinfection and pro-healing abilities in vivo.

Rapid Preparation of AgNPs Carrying Gauze Fiber
The color of the gauze indicates the loading capacity of the AgNPs on the gauze fibers. As shown in Figure 2A, no significant color difference was observed between the bare gauze (Gauze) and quercetin coated gauze (Q-G), regardless of the UV treatment. The quercetin solution adsorbed on the gauze was observed by Video S1 (Supporting Information) to rapidly turn white in a few seconds under acidic conditions. Then, after ultrasound and shock for 10 min each, a large amount of quercetin was still seen to dissociate using the lye drop added to the gauze, which tenta-tively proved that the quercetin coating constructed by the alkaliacid redeposition method on the gauze was considerably stable. The yellow coloration of Q-G that treated by silver nitrate solution (Ag-Q-G) and the gauze treated by the same solution(Ag-G) indicates the presence of AgNPs on the gauze fiber surface, www.advancedsciencenews.com www.advmatinterfaces.de with the formation of AgNPs facilitated by the quercetin coating.
UV irradiation further promoted the generation of AgNPs, especially Ag-Q-G, which exhibited a deep yellow color. This suggests that the quercetin-coated gauze fiber is the most effective at reducing Ag + ions to AgNPs under UV irradiation.
The quercetin load on the gauze was determined using UV-vis spectroscopy. First, Q-G was immersed in an alkaline solution to dissolve quercetin, and the absorbance of the solution was measured. The amount of quercetin loaded onto Q-G was calculated based on the following standard curve:( Figure S1, Supporting Information) Y = 88.53 * X + 0.01607, R 2 = 0.9991 (1) where Y is the optical density, X is the concentration, and R 2 is the correlation coefficient.
The results showed that the amount of quercetin loaded onto the gauze exhibited a positive linear relationship with the feeding concentration of quercetin. When the feed concentration was 10 mg mL −1 , the load of quercetin was 1.18 ± 0.07 mg cm −2 . This loaded amount of quercetin was significantly higher than that in previously reported methods, [22] which effectively served as a reducing agent for subsequent silver reduction at the interface.
During silver reduction and AgNP formation, quercetin undergoes continuous oxidation, which transforms its phenolic hydroxyl group into a quinone group, [23] thereby disrupting hydrogen bonding in the quercetin coating. As shown in Figure 2C, quercetin on the Q-G surface significantly decreased after the reaction with AgNO 3 solution with or without UV irradiation.
Especially in the "With UV" group, quercetin consumption was observed to be over 86% higher than in the Ag-Q-G group (Q-G: 1.03 ± 0.08 mg cm −2 vs Ag-Q-G: 0.14 ± 0.04 mg cm −2 ), indicating that UV irradiation considerably promoted the process of silver reduction and AgNP formation. The use of UV light resulted in a greater reduction efficacy of Ag + compared to that in the dark and natural conditions because of the formation of some reactive species with strong reducing ability in the system under UV irradiation, such as hydrated electrons and reducing radicals. [17] Hydronium is a highly reactive and strongly reducing species generated by the ionization of aromatic compounds in natural organic matter under UV irradiation. [24] Therefore, during this reaction, quercetin serves as a hydrated electron donor and accelerates the photochemical reaction by depleting itself.
The surface morphology of the gauze fibers in each group was observed by SEM ( Figure 2D). The original gauze fibers displayed oriented streaks that became smooth after being coated with quercetin. Various water-insoluble plant polyphenols were also studied for gauze treatment following the same protocol as for quercetin. However, only quercetin provided a uniform coating on the fiber, whereas the other polyphenols formed irregular particles ( Figure S2, Supporting Information). The streaks reappeared after Q-G reacted with AgNO 3 , indicating significant consumption of quercetin during this redox reaction. The surfaces of the Ag-Q-G fibers exhibited numerous cubic or spheroidal Ag-NPs, and their distribution was uniform, as confirmed by EDS ( Figure 2F). The TEM results further confirmed the formation of AgNPs. As shown in Figure 2E, the size distribution of the silver particles was relatively uniform, and high-resolution images re-vealed the typical Ag(111) plane of metallic silver. The observed intercrystalline spacing measures 0.24 nm, which is consistent with previous reports. [25] Phytochemically mediated green synthesis of AgNPs has drawn considerable attention in recent years owing to its better control of the size and shape of the AgNPs. [21] The phenolic hydroxyl group in quercetin serves both as a reductant and stabilizer of in situ formed AgNPs, [26,27] guaranteeing their uniform particle size and adhesion to the surface. [28] In the XPS survey spectra of Ag-Q-G, the appearance of Ag3d peaks at 368.08 and 374.08 eV further indicated the successful synthesis and immobilization of AgNPs ( Figure 2G). In addition, analysis of the C1s high-resolution spectra of different samples confirmed that the quercetin coating was consumed after the generation of AgNPs. As shown in Figure 2H, the deconvolution curves indicate that the carbonyl (C=O) content on the surface of Q-G was considerably increased compared to that of the gauze. Because the main component of the gauze fiber is cellulose without carbonyl groups, which are abundant in quercetin, the increase in C=O confirmed the existence of the quercetin coating on Q-G. After the reaction of Q-G with the AgNO 3 solution, the content of C=O dramatically decreased, and the profile of Ag-Q-G was similar to that of the gauze, confirming the exhaustion of quercetin.
The load and release behaviors of Ag are important for the antibacterial efficiency and duration of Ag-Q-G. The total silver load and cumulative silver release were determined by ICP-AES. As shown in Figure 2I, the total silver load on the gauze was 0.78 ± 0.06 mg cm −2 , disclosed that the average AgNPs generation rate during the preparation process was up to 156 μg cm −2 min −1 . The release of silver in PBS increased over time, accompanied by a burst release of 30.8% on the first day. Afterward, the release rate slowed, reaching almost a plateau after 7 days. By day 15, the accumulated silver release was 0.69 ± 0.15 mg cm −2 , accounting for 88.6% of the total silver content (indicated by the red dotted line: 0.78 ± 0.06 mg cm −2 ).

Antibacterial Performance of Modified Gauze
The skin tissue is constantly exposed to the external environment. Hence, it can easily be infected with harmful bacteria, especially after mechanical injuries, burns, or surgery. [29] Therefore, it is crucial to use antibacterial gauze to prevent bacterial infection and promote wound healing by releasing sufficient antibacterial substances on the surface of the gauze.
Zone of inhibition (ZOI) tests, colony counting on an agar plate, and turbidimetry were used to evaluate the antibacterial activity of the samples against S. aureus and E. coli, the most common pathogens involved in skin infections. These comprehensive antimicrobial evaluations enabled us to clearly understand the antibacterial activity of gauzes with different Ag contents.
After co-culturing with S. aureus and E. coli, no notable inhibition ring was observed around the gauze, Q-G, Ag-Q-G 0.01 , Ag-Q-G 0.05 , and Ag-Q-G 0.1 , and only the samples of Ag-Q-G 0.5 and Ag-Q-G 1 exhibited antimicrobial activity ( Figure 3A). To quantify the antibacterial efficiency of the AgNPs-carrying gauze, all samples were cultured with S. aureus and E. coli solution (1×10 6 CFU mL −1 ), followed by the spreading of the incubated solution on the agar plate. The growth of S. aureus and E. coli is shown in Figure 3B, and the colonies were counted ( Figure 3C,D). The results showed that Ag-Q-G 0.5 and Ag-Q-G 1 exhibit a significantly stronger antibacterial efficiency with antibacterial rates up to 90.68% ± 1.41% and 99.57% ± 0.52% against S. aureus, and 85.62% ± 7.28% and 95.59% ± 1.50% against E. coli, respectively. Interestingly, both gauze and Q-G promoted bacterial growth, which may be ascribed to the numerous gauze attachment sites. [30] With an increase in the AgNP load on the gauze, a gradual increase in the antibacterial ability was observed in the turbidimetric test. Analysis of the optical density at 660 nm showed that Ag-Q-G 0.5 and Ag-Q-G 1 demonstrated a significantly stronger antibacterial capacity than the other groups ( Figure 3D).
Thereafter, the recyclability of the antibacterial gauze was determined. As shown in Figure S3 (Supporting Information), the results showed that although the consumption of silver after each experiment resulted in a gradual attenuation of antibacterial activity in subsequent testing, it still exhibited significant antibacterial efficacy compared to the blank gauze, even after three cycles. This antibacterial gauze appeared to exhibit greater efficacy against S. aureus than against E. coli, which was consistent with a previous study. [31] The comprehensive results showed that quercetin-coated gauze treated with 0.5 and 1 mg mL −1 of AgNO 3 can effectively hinder bacterial growth. Among them, Ag-Q-G 1 exhibited the www.advancedsciencenews.com www.advmatinterfaces.de strongest antibacterial activity. It is crucial to note that higher Ag loads may also lead to potential toxicity, [32] thus the cytocompatibility of each sample must be assessed in future experiments to identify the most appropriate option for application.

Cytocompatibility Evaluation
To determine the cytocompatibility of each sample, viability, and growth morphology tests were performed on the L-929 cells. First, 1 cm 2 of the monolayer sample was soaked into the 1 mL of medium for 24 h, then 100 μL of the medium was transferred into a 96-well plate, and 200 mL of cell suspension (L-929, 2 × 10 5 pcs mL −1 ) was added before incubating for 1, 3, and 5 days. Cell proliferation and viability were detected using the CCK-8 kit and cell morphology was revealed by crystalline violet staining.
As shown in Figure 4A, Ag-Q-G 0.5 and Ag-Q-G 1 demonstrated significant inhibition of L-929 cells, characterized by translucent antibacterial rings, whereas the other samples with less or no AgNP load showed favorable cell proliferation after 1 day of culture. However, the cytotoxic effects of Ag-Q-G 0.5 and Ag-Q-G 1 diminished with incubation time. Attenuated cytotoxicity was observed for Ag-Q-G 0.5 and Ag-Q-G 1 on days 3 and 5, respectively. Notably, the cytotoxicity of Ag-Q-G 0.5 was no longer significantly different from that of the other samples with lower AgNP loads after 5 days of incubation, which is consistent with the results of crystalline violet staining of L-929 cells on day 5 ( Figure 4B).
All groups except Ag-Q-G 1 showed high cell densities with a tightly arranged monolayer. The presence of AgNPs resulted in slightly lower cell densities than in the silver-free groups. In gauze, Q-G, and Ag-Q-G 0.01-0.5 groups, the cells showed normal morphology as shuttle, star, or irregular polygons, indicating that the cells maintained good activity on day 5. However, many round dead cells (indicated by red arrows) were observed in Ag-Q-G 1 , suggesting that gauze with a high silver content is not suitable for subsequent animal studies.
In summary, the antibacterial results revealed that Ag-Q-G 0.5 and Ag-Q-G 1 effectively inhibited bacterial growth in vitro. The in vitro cell tests revealed that the gauze, Q-G, and Ag-Q-G 0.01-0.5 are more cytocompatible. Therefore, it was reasonable to choose Ag-Q-G 0.5 for animal experiments to determine its anti-infection and wound-healing effects in rats.

Healing Effect of Ag-Q-G Dressing on the Morphology of Infected Wound
Rats are one of the most commonly used animal models of wound healing owing to their accessibility, ease of handling, efficiency, and low cost. [33] However, it should be noted that the skin anatomy of rats and humans differ. For example, rats rely heavily on wound contraction, whereas humans rely heavily on re-epithelialization and granulation tissue formation. [34] Dorsal skin excision is commonly used in rats to create a skin injury model because it allows for consistent uniformity in wound size and depth.
In the animal experiments, Ag-Q-G 0.5 (marked as Ag-Q-G in the following text) and gauze were selected as the experimental and control groups, respectively. A few drops of bacterial solution were added to the excised site to initiate wound infection.
The wound was then covered and fixed with a gauze dressing to observe morphological changes in the wound after different healing periods (Figure 5A). Photographs and percentages of wound contraction after excision on days 7, 10, and 14 of gauze dressing treatment are shown in Figure 5B,C, respectively.
As shown in Figure 5B, Ag-Q-G noticeably accelerated wound healing. No noticeable inflammatory features, such as redness, swelling, or pus exudation, were observed at any time point during healing. However, clear scabs were observed in the gauzeand Q-G-treated groups on days 7 and 10. Crusting was particularly pronounced in the gauze treatment group on day 7, which may have been due to excessive pus secretion from the wound in the initial stages of infection that gradually dried. As shown in Figure 5C, the closure rate of the wound area was ≈43.60% ± 6.08% in the gauze group and 83.57% ± 3.74% in the Ag-Q-G group, respectively, on day 7. It increased to 70.50% ± 6.21% and 91.57% ± 3.40% in the gauze and Ag-Q-G groups, correspondingly, one day 10. On day 14, the Ag-Q-G-treated wounds were almost completely healed (93.20% ± 2.61%), which clearly demonstrated the advantages of Ag-Q-G in the treatment of infected wounds.

Histological evaluations
Wound healing is a comprehensive and dynamic process, which involves coagulation, inflammatory responses, cellular proliferation, and tissue remodeling. It is influenced by various factors, making it a challenging and comprehensive treatment option for wound healing. [34] Inflammation caused by bacterial infections may prolong the phases of inflammation, proliferation, or remodeling, resulting in tissue fibrosis and non-healing ulcers. [35] Therefore, the effective use of antibacterial dressings is of considerable importance for protecting the wound, preventing infection, and adsorbing exudates, which ultimately promote wound healing.
When the inflammatory phase is controlled, the periwound tissue enters the proliferative phase. The wound edge gradually contracts and moves toward the center of the wound, and the epithelial cells grow in a transgressive manner from the wound edge. As the wound is completely covered by the epithelium with new blood vessels underneath, collagen fiber remodeling from the edges and base toward the center of the wound leads to wound shrinkage. [36] To evaluate the quality of regenerated skin tissue in infected defects treated with antibacterial gauze, histological analysis of newly formed tissue on tissue remodeling, neoangiogenesis, and inflammation regression was performed.
As shown in Figure 6A, gauze-treated wounds exhibited thicker crusts, granulation tissue formation, and epidermal fragmentation, with a disorganized cellular hierarchy. Over time, the epidermis was continuously remodeled from the edge to the center of the wound. On day 14, epidermal remodeling was completed and a significant amount of neovascularization was observed, with the healing wound being faster in the Ag-Q-G group than in the gauze-treated wounds. On day 10, epidermal remodeling was completed, with the formation of the basal layer, epithelial pegs, and hair follicles, and a large amount of neovascularization and collagen fibers were observed. On day 14, the epidermis  and dermis became thinner, resembling normal tissue, and sebaceous glands and hair follicles had formed.
The tissue section thickness was set to 100 μm and the new epidermal was measured at 300 μm from the edge. From days 7 to 14, the epidermal thickness gradually decreased during wound healing. The epidermal thickness of the Ag-Q-G group was significantly lower than that of the gauze group on days 7 and 10, which remained stable from day 10 onward (Figure 6B). Neovascularization in the marginal neonatal tissue was quantified at the same magnification. As shown in Figure 6C, neovascularization increased in both the gauze and Ag-Q-G groups from day 7 to 14, with the Ag-Q-G group showing significantly better neovascularization than the gauze group. These results suggested that Ag-Q-G reduced the adverse impact of early infection on wound healing by delivering antibacterial AgNPs, thus attenuating the inflammatory response and promoting tissue remodeling.
However, it is important to consider that the residual trace amount of quercetin in the gauze may have a beneficial effect on the regulation of inflammation. Quercetin is known for its longlasting and powerful anti-inflammatory properties, [37] as well as its ability to inhibit LPS-induced mRNA levels of TNF-and interleukin-1 , thereby reducing the adverse effects of endotoxins from bacterial infections. [38] In summary, an antibacterial gauze with rapidly prepared AgNPs on a quercetin coating promoted the healing of infected skin wounds.

Conclusion
In summary, our study proposes a novel and eco-friendly method for the rapid preparation of an antimicrobial gauze containing AgNPs. An alkali-acid re-deposition technique was used to uniformly coat the gauze surface with quercetin. UV radiation accelerated the formation of AgNPs on the quercetin coating, which was accompanied by quercetin consumption. The AgNPscarrying gauze exhibited favorable biocompatibility and antibac-terial ability in vitro and demonstrated anti-inflammatory, proregenerative, and pro-regenerative properties in vivo. Our findings suggest that this green and efficient strategy could be a practical option for the large-scale manufacturing of antibacterial gauze dressings.
Sample Preparation: Medical gauze was cut into 4 cm × 4 cm singlelayer square samples. The sterilized gauze was divided equally into two groups for sample preparation: one group was prepared under natural light and the other was prepared in a UV reaction chamber.
A blank gauze from each group was placed in 75% alcohol solution under ultrasonic shock, rinsed repeatedly with distilled water, and then dried, set as a control group, and marked as Gauze. Another gauze sample from each group was immersed in AgNO 3 solution (1.0 mg mL −1 ) for 5 min, rinsed repeatedly using distilled water, then dried, marked as Ag-G. The remaining gauze samples were immersed in a 2 mg mL −1 quercetin solution (pH 9), swiftly removed, and transferred to pH 1 HCl solution for 10 s. Thereafter, they were repeatedly rinsed with distilled water, dried, and labeled Q-G (the preparation process and coating stability are shown in Video S1, Supporting Information). To form AgNPs on the surface of the gauze fiber, several pieces of QG from each group were immersed in different concentrations of AgNO 3 solution (0.01, 0.05, 0.1, 0.5, and 1.0 mg mL −1 ), irradiated under natural light or UV for 5 min, rinsed repeatedly using distilled water, dried, and labeled as Ag-Q-Gx, where x is the feeding concentration of the AgNO 3 solution in mg mL −1 .
Sample Morphology and Elemental Analysis: Samples of G, Q-G, and Ag-Q-G were randomly selected and sprayed with gold for 30 s. SEM was used to observe morphological changes in each group of samples. The presence and distribution of the AgNPs on the gauze surface were verified using EDS. For TEM analysis, the AgNP suspension was initially obtained by the ultrasonic treatment of Ag-Q-G. Subsequently, meticulous sample preparation involved the deposition of a single droplet of the AgNP suspension onto a grid. Both the TEM and high-resolution TEM (HR-TEM) images were acquired using a Jeol JEM-2100 electron microscope (Japan) operated at a voltage of 200 kV. The elemental compositions of the coatings were measured using XPS, which was supplied with monochromatic A1 K (1486.6 eV) and operated at 12 kV × 15 mA at a pressure of 20 × 10 −6 Pa. Using 300 eV pass energy, overview XPS spectra were obtained between 50 and 1300 eV at 0.5 eV energy steps. The detailed spectra of the peaks of interest were obtained with a 0.05-eV energy step. Each sample had 15 min of total acquisition time. The gauze was precompressed to enhance its compactness and facilitate characterization by XPS.
Quantification Of Quercetin: To generate a standard curve for quercetin, an appropriate quantity of the compound was dissolved in 75% ethanol and then serially diluted with the same ethanol to obtain seven concentrations (0.02, 0.01, 0.005, 0.0025, 0.00125, 0.000625, and 0.0003125 mg mL −1 ). The corresponding absorbance at each concentration was measured using UV-vis at a wavelength of 360 nm, and the data were used to generate a linear fitting curve using Excel (Microsoft Office, USA). Each experiment was independently repeated thrice. To quantify the mass of quercetin on the modified gauze, the samples were cut into 1 × 1 cm 2 , immersed in 1 mL of NaOH solution at pH 13, and subjected to ultrasonic treatment for 1 min. The eluate was subsequently diluted and quantified at 360 nm using UV-vis spectroscopy; the concentration was determined using a standard curve. Finally, the quercetin content of the gauze was determined based on the elution concentration.
Quantification Of Silver Content: The prepared Ag-Q-G set was cut into several square monolayer gauzes of 1-cm 2 size and subsequently soaked in PBS. The Ag content in the solution was detected by ICP-AES at 1, 3, 7, and 15 days, and Ag at 328.068 nm was selected as the analytical spectrum for this method. The remaining operating conditions were as follows: the power, 1.10 kW, carrier gas flow rate, 0.50 L min −1 , and observation height, 7 mm. The total Ag content was measured by ICP-AES after dissolving the Ag on the gauze surface with concentrated nitric acid.
Antibacterial Test: After resuscitation of the cryopreserved strain, the isolated colonies of S. aureus and E. coli were selected using an inoculation loop, transferred to a BHI medium, and incubated for 24 h. The bacterial suspension was adjusted to a density of 1 × 10 6 CFU mL −1 . For the Inhibition Ring Test, 100 μL of the diluted bacterial solution was added to the agar medium. The mixture was evenly coated, and a sample from each group was placed at the center of the agar medium. After incubation at 37°C for 24 h, the inhibition ability of each sample was evaluated by observing the size of its inhibition ring. For the turbidity test, the samples were placed in a 24-well plate and immersed in 150 μL of bacterial solution.
The plate was then incubated at 37°C for 24 h. Next, 1 mL of broth was added to each well, and the cells were cultured for another 24 h. Finally, a volume of 150 μL of the cultured solution was drawn from each well to measure the absorbance value at 660 nm using a microplate reader. For colony counting, samples were placed in a 24-well plate and immersed in 150 μL of bacterial solution. The plate was then incubated at 37°C for 24 h. Afterward, 75 μL of the solution from each well was transferred onto agar medium, spread uniformly, and incubated in a bacterial incubator at 37°C and 5% CO 2 for another 24 h. We assessed the inhibitory activity against S. aureus and E. coli by quantifying the colony numbers using ImageJ software. To assess the recyclability of the antibacterial gauze, it was first immersed in a bacterial solution for 24 h to evaluate bacterial growth. The gauze was then removed and gently rinsed with water before soaking in another bacterial solution for a second test. This procedure was repeated (third test) to evaluate the residual antibacterial efficacy.
Cytocompatibility Test: Each group of samples was separately prepared. Two hundred microliters of the extract was added into 96-well plates, and 200 μL of 2×10 5 mL −1 L-929 cell suspension was added to each well and incubated at 37°C and 5% CO 2 in the incubator for 1, 3, and 5 days. Cell proliferation was detected by the CCK-8 method. Thereafter, one sample was taken from each group after 1, 3, and 5 days of culture, fixed in 10% methanol solution 0.5 mL for 30 s, washed with PBS, and stained with crystal violet for 20 min. Finally, the cell number and morphology were observed under an inverted microscope.
Animal Experiment of Wound Healing: This study was approved by the Biomedical Ethics Committee of Anhui Medical University (20160126). Experiments were performed in accordance with The Guide for the Care and Use of Laboratory Animals. The experiment was performed on male SD rats of ≈200 ± 10 g at 8 weeks of age. Eighteen rats were divided equally into three groups. The rats were anesthetized with intraperitoneal injection (10% chloral hydrate, 300 mg kg −1 ). Next, a circular incision, 10 mm in diameter, was made in the upper and lower parts of the skin on the rat's back. The wounds were covered with the samples (4 × 4 cm 2 ) and fixed with sutures. A dorsal incision was made in the rats by random grouping. The control group covered the wound with G samples, coated group covered the wound with Q-G samples, and the experimental group used samples with better bacteriostatic properties and cytocompatibility. Postoperatively, wound dimensions were recorded on days 7, 10, and 14, and the wound closure rate (%) was calculated as a percentage of the wound closure area.
On days 7, 10, and 14, two rats in each group were sacrificed, and the entire layer of traumatic skin was collected. The specimens were fixed in formalin and stained using the H&E kit. Then, light microscope imaging was performed to observe the recovery of the trauma in each group and to measure the thickness of the new epidermis and number of new blood vessels per unit area.
Statistics: GraphPad Prism 8 statistical software was used for analysis. The measurement data were all normally distributed, and the data were expressed as mean ± standard deviation. The in vitro antimicrobial turbidity method A values were compared between groups by one-way ANOVA. CCK-8 method was used to detect A-value and wound healing rate by twoway ANOVA; test level = 0.05.

Supporting Information
Supporting Information is available from the Wiley Online Library or from the author.