Flower-like lignin / AgNPs / MoS2 composite particle, preparation method and application

Abstract

The invention relates to the technical field of biomass nano antibacterial agents, and provides a flower-like lignin / AgNPs / MoS2 composite particle, and a preparation method and application thereof. The preparation method comprises the following steps: firstly, synthesizing flower-like FL-MoS2 composite nanoparticles with rough surfaces by using uniform enzymatic hydrolysis lignin nanoparticles as carriers and thiourea and sodium molybdate as precursors through a hydrothermal method, secondly, loading silver nanoparticles by adopting an in-situ reduction method, and finally preparing the flower-like lignin / AgNPs / MoS2 composite particles. The method has the advantages of simplicity in operation and environmental friendliness. The synthesized flower-like lignin / AgNPs / MoS2 composite particles have peroxidase-like activity and photothermal effect, the unique flower-like morphology of the composite particles significantly enhances the adhesion ability of nano-enzyme to bacteria, and the composite particles achieve the synergistic sterilization effect of PTT / CDT by generating active oxygen, exerting the photothermal effect and continuously releasing Ag < + >.

Description

Technical Field

[0001] This invention relates to the field of biomass nano-antibacterial agents, and in particular to a flower-like lignin / AgNPs / MoS2 composite particle, its preparation method, and its application. Background Technology

[0002] Silver nanoparticles (AgNPs) are widely used in medical devices, textiles, and food packaging due to their high surface area, high thermal stability, ease of surface functionalization, and broad-spectrum antibacterial activity. However, pure AgNPs are prone to aggregation and have poor chemical stability, making them susceptible to reduced antibacterial activity due to environmental factors such as oxygen and ultraviolet radiation. Furthermore, the environmental safety concerns arising from the release of silver ions by AgNPs have been highly controversial. Relying on a single antibacterial mode (such as Ag⁺ release or ROS) has significant limitations, such as the potential for excessive accumulation of silver nanoparticles and decreased bactericidal efficiency with long-term use. Therefore, there is an urgent need to develop a new antibacterial system that combines multiple mechanisms, including physical action, chemokinetic bactericidal action (Ag⁺, ROS), and photothermal bactericidal action, to achieve faster and more efficient bactericidal effects while reducing the amount of AgNPs required. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a flower-like lignin / AgNPs / MoS2 composite particle, its preparation method, and its application.

[0004] The technical solution adopted in this invention is as follows: A method for preparing flower-like lignin / AgNPs / MoS2 composite particles includes the following steps: S1: A dispersion solution containing enzymatically hydrolyzed lignin nanoparticles and PVP and a precursor solution containing sodium molybdate and thiourea are prepared by ultrasonic treatment. The dispersion solution and the precursor solution are then mixed to obtain a mixed solution. S2: The mixed solution is heated by hydrothermal method under high pressure to allow sodium molybdate and thiourea to react fully to generate MoS2, and MoS2 is fully compounded with enzymatically hydrolyzed lignin nanoparticles. After the reaction is completed, the mixture is washed and dried to obtain flower-like lignin / MoS2 composite nanoparticles. S3: The flower-like lignin / MoS2 composite nanoparticles are ultrasonically dispersed to obtain a suspension. AgNO3 solution and ethylene glycol are added to the suspension to carry out an in-situ reduction reaction. After the reaction is completed, the nanoparticles are washed and dried to obtain flower-like lignin / AgNPs / MoS2 composite particles.

[0005] As a preferred embodiment of the present invention, step S1, the preparation of enzymatically hydrolyzed lignin nanoparticles, specifically includes: dissolving initial enzymatically hydrolyzed lignin in an ethanol solution, stirring thoroughly, filtering, removing ethanol from the filtrate by vacuum distillation, washing the first fraction obtained with deionized water and freeze-drying to obtain F1 fraction lignin nanoparticles; dissolving the F1 fraction lignin nanoparticles in a GVL solution and sonicating to obtain a lignin solution; adding the lignin solution dropwise to deionized water to form a suspension, and then dialysis, centrifuging, and freeze-drying to obtain enzymatically hydrolyzed lignin nanoparticles. This pretreatment step can effectively remove impurities from lignin and obtain lignin nanoparticles with uniform size and good dispersibility.

[0006] In a preferred embodiment of the present invention, in step S2, the concentration of the enzymatically hydrolyzed lignin nanoparticles in the dispersion solution is 0.25~5 g / L, the concentration of PVP in the dispersion solution is 2~3 g / L; the concentration of sodium molybdate in the precursor solution is 2~5 g / L, and the concentration of thiourea in the precursor solution is 6~10 g / L; the volume ratio of the dispersion solution to the precursor solution is 1.5~2. This concentration and ratio range ensures that MoS2 grows uniformly on the lignin surface, forming structurally stable flower-like composite particles.

[0007] As a preferred embodiment of the present invention, in step S2, the preparation process of the dispersion solution includes: adding enzymatically hydrolyzed lignin nanoparticles to distilled water and ultrasonically treating for at least 25 minutes, followed by adding PVP and continuing ultrasonic treatment for at least 10 minutes to obtain the dispersion solution; the preparation process of the precursor solution includes: adding sodium molybdate and thiourea to deionized water and ultrasonically treating for at least 10 minutes. Sufficient ultrasonic treatment ensures uniform dispersion of lignin nanoparticles, PVP, sodium molybdate, and thiourea.

[0008] As a preferred embodiment of the present invention, in step S3, the mixed solution is magnetically stirred before the hydrothermal heating for 1.5 to 2.5 hours to further promote the uniform dispersion of each component.

[0009] As a preferred embodiment of the present invention, in step S3, the high pressure condition specifically adopts a sealed high pressure reactor, the heating temperature is 200~250℃, and the heating time is 20 h or more, to promote the vertical growth of MoS2 nanosheets on the lignin surface and form a rough flower-like structure.

[0010] As a preferred embodiment of the present invention, in step S3, the washing is performed by alternating washing with deionized water and ethanol to remove impurities and byproducts, and the drying is performed by freeze drying; in step S4, the washing is performed by washing with deionized water, and the drying is performed by freeze drying, so as to avoid the impact of high temperature on the stability of composite nanoparticles. As a preferred embodiment of the present invention, in step S4, the solvent of the suspension is deionized water, the content of lignin / MoS2 composite nanoparticles in the suspension is 1.5~2.5 mg / mL, and the ultrasonic dispersion time of the suspension is 20 min or more to ensure that the composite particles are uniformly dispersed in the solution.

[0011] As a preferred embodiment of the present invention, in step S4, the concentration of the AgNO3 solution is 0.05~0.07 mol / L, the volume ratio of the AgNO3 solution to the suspension and the volume ratio of the ethylene glycol to the suspension are both 1:4~1:6, and the amount of silver ions added and the reducing environment are controlled to ensure that they can be uniformly and stably loaded on the surface of the flower-shaped composite particles, thereby optimizing their antibacterial and photothermal properties.

[0012] The present invention also provides a flower-like lignin / AgNPs / MoS2 composite particle, which is prepared by the above method.

[0013] The present invention also provides an application of the flower-like lignin / AgNPs / MoS2 composite particles prepared by the above method in antibacterial agents.

[0014] As a preferred embodiment of the present invention, the antibacterial agent is used for photothermal antibacterial and chemokinetic antibacterial purposes.

[0015] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The flower-like lignin / AgNPs / MoS2 composite particles synthesized in this invention exhibit excellent photothermal properties, good photothermal stability, and high photothermal conversion efficiency. Furthermore, these composite particles also demonstrate excellent antioxidant properties and biocompatibility. Combined with mouse experiments, studies have shown that these composite particles significantly improve wound healing rates, with no obvious lesions or inflammation occurring on the wounded skin.

[0016] 2. The flower-like lignin / MoS2 composite particles synthesized in the present invention have irregularly curved MoS2 nanosheets that grow vertically and densely on the surface of enzymatically hydrolyzed lignin nanoparticles. This not only reduces the aggregation of MoS2, but also exposes more active sites. At the same time, the change in topology can greatly improve the roughness of the particle surface, which is more conducive to improving the adhesion of the composite particles. The small size and rough surface morphology can enhance the adhesion to bacteria, further improving the effective antibacterial properties of the material.

[0017] 3. The enzymatically hydrolyzed lignin used in this embodiment is obtained from plant biomass through enzymatic hydrolysis. It is abundant, inexpensive, green and environmentally friendly, and has good biocompatibility and environmental friendliness.

[0018] 4. The present invention uses composite particles prepared from natural lignin nanospheres and MoS2 as carriers for silver nanoparticles, which not only achieves stable dispersion of silver nanoparticles and improves the antibacterial properties of the material, but also increases its biocompatibility and enhances its application potential in fields such as biomedicine, food packaging and textiles. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the implementation of lignin fractionation and lignin nanosphere preparation. Figure 2 This is a schematic diagram of the implementation of flower-shaped lignin / AgNPs / MoS2 composite particles; Figure 3 These are SEM images of flower-like lignin / MoS2 composite particles with different amounts of F1-LNS added; Figure 4 This is a particle size distribution diagram of flower-shaped lignin / MoS2 composite particles with different F1-LNS addition amounts; Figure 5 This is a comparison chart of the photothermal properties of flower-shaped lignin / AgNPs / MoS2 composite particles; Figure 6 This is a comparison chart of the antibacterial properties of flower-shaped lignin / AgNPs / MoS2 composite particles; Figure 7 yes Figure 6 Corresponding bacterial survival rate data statistics chart; Figure 8 This is a schematic diagram of the rat wound antibacterial experiment under the action of flower-like lignin / AgNPs / MoS2 composite particles; Figure 9 These are comparative images showing changes in the morphology of rat skin wounds under different treatment conditions; Figure 10 This is a comparison chart of skin wound healing rate and rat weight changes under different treatment conditions; Figure 11 This is a comparison chart of the number of bacteria isolated from wound tissue under different treatment conditions. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0021] To address the limitations of existing antibacterial agents, this invention proposes a method for preparing flower-like lignin / AgNPs / MoS2 composite particles, thereby achieving a multi-mode synergistic antibacterial material involving physical action, chemical kinetics, and photothermal sterilization. The flower-like lignin / AgNPs / MoS2 composite particles proposed in this invention are based on the following considerations: Firstly, this invention uses enzymatically hydrolyzed lignin nanoparticles as a carrier. Lignin, a natural polymer compound with a unique three-dimensional network structure, can stabilize nanoparticles to prevent aggregation and inhibit the burst release of metal ions, thus enhancing its biocompatibility. Secondly, lignin molecules are rich in methoxy, phenolic hydroxyl, and benzene ring groups, which can not only chelate metal ions but also reduce them to nanoparticles, while simultaneously imparting excellent UV protection properties to the material. Furthermore, lignin, as a protective layer for plants, possesses good antibacterial and antiviral activity, effectively protecting plants from bacterial and viral attacks. In summary, lignin is an ideal carrier for dispersing and loading silver nanoparticles. This invention first performs a simple pretreatment on the lignin carrier to homogenize the lignin nanospheres, and then uses these uniformly dispersed lignin nanospheres as the carrier.

[0022] Secondly, for nanomaterials, nanozymes with rough surfaces and abundant active defect edge sites can effectively enhance their adhesion to bacteria, capture bacteria, and thus improve antibacterial performance. Molybdenum disulfide (MoS2) is widely used in photothermal therapy (PTT) antibacterial applications due to its unique two-dimensional layered structure, large specific surface area, good biocompatibility, and high photothermal conversion efficiency. Furthermore, MoS2 possesses peroxidase-like activity (POD), which can catalyze the generation of highly toxic hydroxyl radicals (•OH) from low concentrations of H2O2 for sterilization. Therefore, this invention uses uniform lignin nanospheres as a carrier and thiourea and sodium molybdate as precursors to synthesize flower-like lignin / MoS2 composite nanoparticles with rough surfaces via a hydrothermal method. Irregularly curved MoS2 nanosheets grow vertically and densely on the surface of the enzymatically hydrolyzed lignin nanoparticles. This not only reduces MoS2 aggregation and exposes more active sites, but also significantly increases the surface roughness of the particles due to the altered topology, thus significantly enhancing the adhesion of the composite particles to bacteria.

[0023] Thirdly, based on the aforementioned flower-like lignin / MoS2 composite nanoparticles, this invention employs an in-situ reduction method to load AgNPs, ultimately preparing flower-like lignin / AgNPs / MoS2 composite particles. The synergistic bactericidal mechanism of these composite particles is as follows: utilizing small-sized lignin nanospheres as a carrier, the composite particles possess the advantage of small size, resulting in a high specific surface area, which increases the contact area between the composite particles and bacteria. After the nanozyme adheres to the bacterial surface, it precisely releases •OH and Ag⁺ to attack the cell wall; simultaneously, the photothermal effect of the MoS2 component rapidly generates high temperatures under laser irradiation, destroying bacterial wall proteins and phospholipids, further enhancing the destructive effect of •OH and Ag⁺ on intracellular components, thereby achieving synergistic and efficient bactericidal action through PTT (photothermal therapy) and CDT (chemokinetic therapy).

[0024] The present invention will now be described in detail with reference to specific embodiments.

[0025] Example 1 First, the required enzymatically hydrolyzed lignin nanoparticles (F1-LNS) are prepared, such as... Figure 1 As shown. The lignin raw material used in this embodiment is enzymatically hydrolyzed lignin, which is derived from the residue of microbial enzymatic hydrolysis of natural plants such as corn stalks to produce ethanol. This lignin, when untreated, contains insoluble impurities and requires pretreatment to obtain homogenized enzymatically hydrolyzed lignin nanoparticles. This pretreatment step ensures the homogeneity and high reactivity of the lignin carrier, laying the foundation for the subsequent construction of composite materials. Figure 1 As shown, the specific pretreatment method includes: adding 30 g of initial enzymatically hydrolyzed lignin nanoparticles to 600 mL of 90% ethanol solution, then magnetically stirring at 300 r / min for 3 h, and separating the mixture into soluble and insoluble residues using vacuum filtration. The filtrate (90% ethanol-soluble fraction, i.e., EHL) is distilled off under reduced pressure to obtain the first fraction (F1) and the 90% ethanol-insoluble fraction (F2). Both lignin fractions are washed with deionized water to avoid interference from ethanol. The washed lignin fractions are then freeze-dried to obtain F1 and F2 fractions of lignin, which are stored in a desiccator for later use. Dissolve 0.8 g of F1 fraction lignin nanoparticles in 80 mL of 90% GVL solution and sonicate for 15 min to completely dissolve the lignin. Quickly add the lignin solution dropwise to 480 mL of deionized water and let stand for 6 min. Place the suspension in a dialysis bag to remove the solvent, and then collect the enzymatically hydrolyzed lignin nanoparticles by centrifugation and freeze-drying.

[0026] After preparing enzymatically hydrolyzed lignin nanoparticles, 0.01 g of the nanoparticles were weighed and dispersed uniformly in 40 mL of distilled water by ultrasonic treatment for 30 min to ensure sufficient dispersion. Subsequently, 0.1 g of PVP (polyvinylpyrrolidone) was added to the suspension, and ultrasonic dispersion was continued for 15 min. Next, 0.15 g of sodium molybdate and 0.3 g of thiourea were ultrasonically dissolved in 20 mL of deionized water for 15 min to form a homogeneous precursor solution. The solutions were mixed and stirred with a magnetic stirrer for 2 h. The mixture was then transferred to a 100 mL sealed high-pressure reactor and heated at 220 °C for 24 h. After the reaction was complete, the nanoparticles were washed five times alternately with deionized water and ethanol, and then freeze-dried to collect the flower-like lignin / MoS2 composite nanoparticles (FL@MoS2). 100 mg of the above sample was taken and ultrasonically dispersed uniformly in 50 mL of deionized water for 30 min. To the obtained suspension, 10 mL of 0.06 mol / L AgNO3 solution and 10 mL of ethylene glycol were added, and the mixture was reacted at 80 °C for 4 h. The product was then washed four times with deionized water. Finally, the washed flower-like lignin / AgNPs / MoS2 composite particles (FL@MoS2-Ag) were dried using freeze-drying technology and stored for later use.

[0027] The preparation process of the above composite particles is as follows: Figure 2 As shown, LNS refers to enzymatically hydrolyzed lignin nanoparticles, CH4N2S is thiourea, and Na2MoO4 is sodium molybdate.

[0028] Example 2 Enzymatically hydrolyzed lignin nanoparticles were prepared according to the method described in Example 1.

[0029] 0.05 g of enzymatically hydrolyzed lignin nanoparticles were weighed and uniformly dispersed in 40 mL of distilled water by ultrasonication for 30 min to ensure complete dispersion. Subsequently, 0.1 g of PVP was added to the suspension, and ultrasonication was continued for 15 min. Next, 0.15 g of sodium molybdate and 0.3 g of thiourea were ultrasonically dissolved in 20 mL of deionized water for 15 min to form a homogeneous precursor solution. The solutions were mixed and stirred with a magnetic stirrer for 2 h. The mixture was then transferred to a 100 mL sealed autoclave and heated at 220 °C for 24 h. After the reaction was complete, the nanoparticles were washed five times alternately with deionized water and ethanol, and then freeze-dried to collect the flower-like lignin / MoS2 composite nanoparticles (FL@MoS2). 100 mg of the above sample was taken and uniformly dispersed by ultrasonication in 50 mL of deionized water for 30 min. To the obtained suspension, 10 mL of 0.06 mol / L AgNO3 solution and 10 mL of ethylene glycol were added, and the mixture was reacted at 80 °C for 4 h. The product was then washed four times with deionized water. Finally, the washed flower-like lignin / AgNPs / MoS2 composite particles (FL@MoS2-Ag) were dried using freeze-drying technology and stored for later use.

[0030] Example 3 Enzymatically hydrolyzed lignin nanoparticles were prepared according to the method described in Example 1. 0.1 g of the enzymatically hydrolyzed lignin nanoparticles were weighed and uniformly dispersed in 40 mL of distilled water by ultrasonic treatment for 30 min to ensure sufficient dispersion. Subsequently, 0.1 g of PVP was added to the suspension, and ultrasonic dispersion was continued for 15 min. Next, 0.15 g of sodium molybdate and 0.3 g of thiourea were ultrasonically dissolved in 20 mL of deionized water for 15 min to form a homogeneous precursor solution. After mixing the solutions, the mixture was stirred with a magnetic stirrer for 2 h. Then, the mixture was transferred to a 100 mL sealed high-pressure reactor and heated at 220 °C for 24 h. After the reaction was completed, the sample was washed five times alternately with deionized water and ethanol, and then freeze-dried to collect the flower-like lignin / MoS2 composite nanoparticles (FL@MoS2). 100 mg of the above sample was taken and uniformly dispersed by ultrasonic treatment in 50 mL of deionized water for 30 min. To the obtained suspension, 10 mL of 0.06 mol / L AgNO3 solution and 10 mL of ethylene glycol were added. The mixture was then reacted at 80 °C for 4 h, followed by four washes with deionized water. Finally, the washed flower-like lignin / AgNPs / MoS2 composite particles (FL@MoS2-Ag) were dried using freeze-drying technology and stored for later use.

[0031] Comparative Example 1 100 mg of F1-LNS nanoparticles obtained in Example 1 were used to compare their photothermal stability, photothermal conversion performance, photothermal heating performance, and antibacterial performance against Escherichia coli and Staphylococcus aureus.

[0032] Comparative Example 2 100 mg of the FL@MoS2 composite particles obtained in Example 1 were used to compare the thermal stability, photothermal conversion performance, photothermal heating performance, and antibacterial performance against Escherichia coli and Staphylococcus aureus.

[0033] The FL@MoS2 composite particles prepared in Examples 1-3 were characterized by scanning electron microscopy, and the results are as follows: Figure 3 , 4 As shown. Figure 3 In the figure, (a) is pure MoS2 synthesized without the addition of F1-LNS, which exhibits a large layered structure. (b), (c) and (d) are the composite particles obtained after adding 0.01g, 0.05g and 0.1g of F1-LNS in Examples 1 to 3, respectively. Figure 4 The particle size distribution statistics of the composite particles prepared in Examples 1-3 are shown. It can be seen that with the increase of F1-LNS addition, MoS2 nanosheets successfully grew vertically on the surface of lignin nanospheres, forming flower-like structures of different sizes and densities. Figure 3 In the morphology shown in (c) (corresponding to Example 2), the irregularly curved MoS2 nanosheets grow densely, forming a rough flower-like structure with the smallest particle size. This not only reduces the aggregation of MoS2, but also exposes more active sites. At the same time, the change in topology can greatly improve the roughness of the particle surface, which is more conducive to improving the adhesion of the composite particles.

[0034] The photothermal properties of dispersions of four samples—F1-LNS, MoS2, FL@MoS2, and FL@MoS2-Ag—were investigated. Near-infrared light (808 nm, 1 W / cm²) was monitored every 30 seconds using an infrared thermal imager. 2 The photothermal effect of the sample was evaluated by the change in solution temperature after irradiation, and the photothermal heating curves of FL@MoS2-Ag composite nanoparticles with different concentrations were assessed. The test results are as follows: Figure 5Figure (a) shows the photothermal heating curves of different sample solutions, (b) shows the photothermal heating curves of FL@MoS2-Ag at different concentrations, (c) shows the temperature change curve of FL@MoS2-Ag during the experiment, and (d) shows the natural cooling curve of FL@MoS2-Ag and the linear fit of t with -Ln(θ). Figure (a) shows that after continuous irradiation for 900 s, the temperature rise of the FL@MoS2-Ag composite particle dispersion is significantly higher than that of PBS buffer, F1-LNS, pure MoS2, and FL@MoS2, demonstrating its excellent photothermal conversion ability. Figure (b) shows that the temperature rise effect of FL@MoS2-Ag becomes more pronounced with increasing concentration. Figure (c) shows that the FL@MoS2-Ag composite nanoparticles have good photothermal stability. Based on the natural cooling curve in Figure (d), the photothermal conversion efficiency (η) of the FL@MoS2-Ag composite nanoparticles can be calculated to be as high as 51.9%. Experimental results show that FL@MoS2-Ag can serve as a novel photothermal agent, enhancing bacterial cell membrane permeability by acting on the bacterial surface, and has broad application prospects in in vitro / in vivo biomedical fields.

[0035] Escherichia coli and Staphylococcus aureus were selected as model strains. The in vitro antibacterial effect of the samples was evaluated using the plate count method. The sample concentration was 50 μg / mL and the H2O2 concentration was 200 μmol / L. The samples were subjected to an 808 nm laser (1.0 W / cm²). 2 Bacterial treatments were performed under irradiation for 15 min and under no-light conditions. Samples were divided into 10 groups: PBS, H2O2, F1-LNS, MoS2, FL@MoS2, FL@MoS2-Ag, F1-LNS+H2O2, MoS2+H2O2, FL@MoS2+H2O2, and FL@MoS2-Ag+H2O2. Results are as follows... Figure 6 , 7 As shown. Among them, Figure 6 upper part and Figure 7 The left half shows colony images and bacterial survival rate data of E. coli in each group of samples under near-infrared (+NIR) and non-near-infrared (-NIR) lighting conditions. Figure 6 lower half and Figure 7 The right half shows images of Staphylococcus aureus colonies and bacterial survival rate data under near-infrared (NIR) light and non-NIR light conditions in each sample group. The figures show that without NIR light, FL@MoS2-Ag exhibits significantly stronger bactericidal performance due to the combined effect of silver ions (Ag⁺) and hydroxyl groups (•OH). After NIR light application, almost no bacteria survive in the FL@MoS2-Ag+H₂O₂+NIR system. These results indicate that FL@MoS2-Ag nanocomposite particles possess significant antibacterial potential, and their effectiveness can be enhanced through synergistic interaction with CDT / PTT.

[0036] The antibacterial properties of the products from the examples were tested using animal experiments. Figure 8 As shown, an incision of approximately 10 mm was constructed on the back of the rat, and Staphylococcus aureus (1×10⁻⁶) was used. 7 Rats were infected with CFU / mL and then treated for 11 days using different samples combined with 808nm near-infrared light. Rats were divided into five groups according to different treatment methods: (I) control group (PBS), (II) treatment group (FL@MoS2-Ag), (III) CDT treatment group (FL@MoS2-Ag+H2O2), (IV) PTT treatment group (FL@MoS2-Ag+NIR), and (V) PTT / CDT combined treatment group (FL@MoS2-Ag+NIR+H2O2).

[0037] Figure 9 The wound closure process of all groups was recorded. Figure 10 The left half shows the wound healing rate assessment of different treatment groups. The observation found that the wound healing ability of the treatment groups was better than that of the control group, and the wound closure speed of group V was the fastest. After 11 days of treatment, the wound healing rate of group I (control group) was 32.89%, while that of group V was 94.06%, which confirms that the FL@MoS2-Ag composite antibacterial material is beneficial to wound healing. Figure 10 The right half of the diagram shows the changes in body weight of rats in each group during the experiment. The results show that the weight gain trend of the experimental group mice was basically consistent with that of the control group, confirming that the FL@MoS2-Ag material has low biotoxicity. Group V showed relatively higher body weight at each time point, indicating that wound infection was well controlled. Finally, wound fluid samples were taken on days 1, 3, 5, and 11 of treatment and cultured on LB agar plates to verify the antibacterial effect of the material in practical use. The results are as follows... Figure 11 As shown, observations revealed a significant decrease in colony counts in groups II through V, with group V exhibiting the lowest colony count. This result is consistent with in vitro antibacterial experimental data. In conclusion, the flower-like FL@MoS2-Ag-based PTT / CDT synergistic antibacterial therapy can effectively combat bacterial wound infections in vivo.

[0038] Compared with Comparative Examples 1 and 2, this demonstrates that FL@MoS2-Ag can serve as a novel photothermal agent, enhancing bacterial cell membrane permeability by acting on the bacterial surface, exhibiting significant antibacterial potential. Furthermore, its effectiveness can be enhanced through synergistic action with CDT / PTT. It shows broad application prospects in in vitro / in vivo biomedical fields. In summary, the flower-like lignin / AgNPs / MoS2 composite particles synthesized in this invention significantly enhance the adhesion of nanozymes to bacteria due to their unique flower-like morphology. By generating reactive oxygen species (ROS), exerting a photothermal effect, and continuously releasing silver ions (Ag+), it achieves a synergistic bactericidal effect of PTT / CDT.

[0039] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing flower-like lignin / AgNPs / MoS2 composite particles, characterized in that, Includes the following steps: S1: Prepare enzymatically hydrolyzed lignin nanoparticles; S2: A dispersion solution containing enzymatically hydrolyzed lignin nanoparticles and PVP and a precursor solution containing sodium molybdate and thiourea are prepared by ultrasonic treatment. The dispersion solution and the precursor solution are then mixed to obtain a mixed solution. S3: The mixed solution is heated by hydrothermal method under high pressure to allow sodium molybdate and thiourea to fully react and generate MoS2. MoS2 is fully combined with enzymatically hydrolyzed lignin nanoparticles. After the reaction is completed, the mixture is washed and dried to obtain flower-like lignin / MoS2 composite nanoparticles. S4: The flower-like lignin / MoS2 composite nanoparticles are ultrasonically dispersed to obtain a suspension. AgNO3 solution and ethylene glycol are added to the suspension to carry out an in-situ reduction reaction. After the reaction is completed, the nanoparticles are washed and dried to obtain flower-like lignin / AgNPs / MoS2 composite particles.

2. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S1, the preparation of enzymatically hydrolyzed lignin nanoparticles specifically includes: dissolving initial enzymatically hydrolyzed lignin in an ethanol solution, stirring thoroughly, filtering, removing ethanol from the filtrate by vacuum distillation, washing the first fraction obtained by separation with deionized water and freeze-drying to obtain F1 fraction lignin nanoparticles; dissolving the F1 fraction lignin nanoparticles in a GVL solution and sonicating to obtain a lignin solution, adding the lignin solution dropwise to deionized water to form a suspension, and then dialysis, centrifuging, and freeze-drying to obtain enzymatically hydrolyzed lignin nanoparticles.

3. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S2, the concentration of the enzymatically hydrolyzed lignin nanoparticles in the dispersion solution is 0.25~5 g / L, the concentration of PVP in the dispersion solution is 2~3 g / L; the concentration of sodium molybdate in the precursor solution is 2~5 g / L, the concentration of thiourea in the precursor solution is 6~10 g / L; and the volume ratio of the dispersion solution to the precursor solution is 1.5~2.

4. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S2, the preparation process of the dispersion solution includes: adding enzymatically hydrolyzed lignin nanoparticles to distilled water and ultrasonically treating for more than 25 minutes, then adding PVP and continuing ultrasonic treatment for more than 10 minutes to obtain the dispersion solution; the preparation process of the precursor solution includes: adding sodium molybdate and thiourea to deionized water and ultrasonically treating for more than 10 minutes.

5. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S3, the mixed solution is magnetically stirred before the hydrothermal heating for 1.5-2.5 hours; the high-pressure condition is specifically achieved using a sealed high-pressure reactor, with a heating temperature of 200-250°C and a heating time of 20 hours or more; the washing is performed by alternating washing with deionized water and ethanol, and the drying is performed by freeze drying; in step S4, the washing is performed by washing with deionized water, and the drying is performed by freeze drying.

6. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S4, the solvent of the suspension is deionized water, the content of lignin / MoS2 composite nanoparticles in the suspension is 1.5~2.5 mg / mL, and the ultrasonic dispersion time of the suspension is 20 min or more.

7. The method for preparing flower-like lignin / AgNPs / MoS2 composite particles according to claim 1, characterized in that, In step S4, the concentration of the AgNO3 solution is 0.05~0.07 mol / L, and the volume ratio of the AgNO3 solution to the suspension and the volume ratio of the ethylene glycol to the suspension are both 1:4~1:

6.

8. A flower-like lignin / AgNPs / MoS2 composite particle, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The application of flower-shaped lignin / AgNPs / MoS2 composite particles prepared by the method according to any one of claims 1-7 in antibacterial preparations.

10. The application according to claim 9, characterized in that, The antibacterial agent is used for photothermal antibacterial and chemokinetic antibacterial purposes.

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