Preparation method and application of prodigiosin and tannic acid self-assembled nanoparticles

Abstract

The invention belongs to the technical field of biological medicine, and discloses a prodigiosin (PG) and tannic acid (TA) self-assembled carrier-free nano-particle as well as preparation and application thereof. The particles are formed by PG and TA through nano-precipitation self-assembly, and the particle size is 30-50 nm. The preparation method comprises the following steps: respectively dissolving PG and TA in DMSO, mixing and stirring according to a molar ratio of (5-10): 1, dropwise adding ddH2O, carrying out ultrasonic treatment, dialyzing to remove a solvent, centrifuging, taking precipitate, and freeze-drying to obtain powder. The nanoparticles can efficiently kill methicillin-resistant staphylococcus aureus and other multi-drug-resistant bacteria, remove excessive ROS, inhibit TNF-alpha, IL-1beta and IL-6 and promote expression of IL-4, IL-10 and TGF-beta, so that infected skin flap necrosis is relieved, skin repair is promoted, and the nanoparticles have good biological safety and can be used for preparing antibacterial and infected wound treatment drugs.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology and relates to a carrier-free nanoparticle with antibacterial, antioxidant, anti-inflammatory and skin tissue repair-promoting properties, its preparation method and application, specifically involving the preparation method and application of tannic acid and styraxin nanoparticles. Background Technology

[0002] Skin flap transplantation is a cornerstone of plastic surgery, but it faces ongoing challenges due to a high failure rate (15%-30%) caused by infection, ischemia-reperfusion injury, and inflammatory dysregulation. Infected flaps create a self-perpetuating pathological cycle: bacterial biofilm formation affects antibiotic penetration, while neutrophil over-infiltration and macrophage-derived pro-inflammatory cytokines (such as IL-1β and TNF-α) exacerbate oxidative stress and tissue necrosis. Overactivation of the NLRP3 inflammasome amplifies macrophage sepsis and maintains M1 macrophage polarization, disrupting the transition to the healing-promoting M2 phenotype necessary for angiogenesis and extracellular matrix remodeling. Current strategies, including debridement and systemic antibiotics, often fail to address biofilm intractability, modulate immune cell plasticity, or neutralize reactive oxygen species (ROS), thus highlighting the unmet need for therapies that simultaneously target infection, inflammation, and redox imbalance.

[0003] Prodigiosin (PG) is a microbially derived protoinosine alkaloid, a secondary metabolite synthesized by bacteria such as *Serratia marcescens*, possessing dual therapeutic potential: potent broad-spectrum antibacterial activity against drug-resistant pathogens, and immunomodulatory effects through inhibition of NF-κB signaling and promotion of M2 macrophage polarization. Tannic acid (TA) is a plant polyphenol that can serve as a natural antioxidant and self-assembling scaffold, scavenging ROS and stabilizing nanostructures through multivalent hydrogen bonds. However, the clinical application of PG is limited by its poor water solubility and rapid clearance, while TA is affected by pH instability and non-specific protein binding. Supramolecular self-assembly offers a promising strategy to overcome these limitations, enabling the co-administration of hydrophobic and hydrophilic agents with enhanced stability, controlled release, and synergistic bioactivity. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a self-assembled nanoparticle of lecithin and tannic acid with good antibacterial effect, low likelihood of inducing bacterial resistance, and ability to promote skin repair. It also provides a simple, green and environmentally friendly, and time-saving self-assembly preparation method and correspondingly provides the application of the above-mentioned self-assembled nanoparticles of lecithin and tannic acid in the preparation of antibacterial drugs and the preparation of skin flap treatment drugs for methicillin-resistant Staphylococcus aureus infection.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A self-assembled nanoparticle of styraxin and tannic acid is mainly composed of two small molecule drugs, styraxin and tannic acid. The styraxin and tannic acid are self-assembled into supramolecular nanoparticles by nanoprecipitation. The particle size of the nanomaterial is 30 nm to 50 nm.

[0007] The aforementioned lecithin and tannic acid self-assembled nanoparticles can be used for antibacterial, anti-inflammatory, and skin tissue repair promotion.

[0008] As a general technical concept, the present invention also provides a method for preparing the above-mentioned self-assembled nanoparticles of styracin and tannic acid, characterized by comprising the following steps:

[0009] (1) Dissolve styracil and tannic acid separately in DMSO solution;

[0010] (2) Mix and stir the styracin and tannic acid solution in a certain molar mass ratio to prepare DMSO mixture;

[0011] (3) Add the DMSO mixture dropwise into ddH2O at a certain ratio and sonicate to obtain a dispersion of lecithin and tannic acid nanomaterials.

[0012] (4) The dispersion of styraxin and tannic acid nanomaterials was dialyzed to obtain a dialysis solution containing the dispersion of styraxin and tannic acid nanomaterials. The dispersion was centrifuged, and the precipitate was freeze-dried to obtain styraxin and tannic acid self-assembled nanoparticle powder.

[0013] In the preferred embodiment of the above-mentioned method for preparing self-assembled nanoparticles of sphaerocin and tannic acid, in step (2), the molar mass ratio of the sphaerocin and tannic acid solution is 5-10:1, and the molar concentration of the sphaerocin is 2.5 mM. In step (3), the volume ratio of the DMSO mixture to ddH2O is 1:9. In step (4), the molecular weight cutoff of the dialysis bag is 2500D-3500D.

[0014] In the preferred embodiment of the above-mentioned method for preparing self-assembled nanoparticles of styrax rubigin and tannic acid, the stirring time in step (2) is 5-10 min, the sonication time in step (3) is 5-10 min, the dialysis time in step (4) is 20-24 h, the centrifugation speed is 13000 rpm-14000 rpm, and the centrifugation time is 20-30 min.

[0015] As a general technical concept, the present invention provides the application of the self-assembled nanoparticles of styracin and tannic acid prepared by the above-mentioned preparation method in the preparation of antibacterial drugs and drugs for treating flap infections induced by multidrug-resistant bacteria.

[0016] In the above applications, preferably, the drug can be used to eliminate multidrug-resistant bacteria and effectively treat skin flap infections induced by multidrug-resistant bacteria, such as effectively treating chronic wound infections in diabetic patients; the antibacterial drug is mainly used on the skin.

[0017] The main innovation of this invention lies in:

[0018] (1) Selection of raw materials, lecithin and tannic acid and their combination methods.

[0019] The nanomaterials of this invention are composed of squalene and tannic acid. Squalene possesses excellent antibacterial, anti-inflammatory, and antioxidant activities, while tannic acid, rich in phenolic hydroxyl groups, provides a self-assembly scaffold and hydrogen bonds. The binding mechanism between squalene and tannic acid is crucial to the efficacy of the nanomaterials. The phenolic hydroxyl groups in tannic acid can form numerous hydrogen bonds with the nitrogen atoms in squalene. Tannic acid and squalene form aggregates in water, avoiding hydrophobic interactions upon contact with water, thus driving the self-assembly of the two substances into nanoparticles. This carrier-free, artificially modified binding mechanism significantly improves the solubility of squalene, reduces toxicity, and maximizes the pharmacological activities of both squalene and tannic acid. The non-covalent bonding between squalene and tannic acid allows for easy dissociation into unimolecular molecules in the infection microenvironment, enhancing their effectiveness.

[0020] This invention is the first to utilize a self-assembly technique to prepare nanomaterials from styraxin and tannic acid, which can be widely applied to the antibacterial and healing-promoting treatment of skin, traumatic, or surgical infections. These nanomaterials utilize the intermolecular interactions between styraxin and tannic acid to self-assemble into carrier-free nanoparticles. While retaining the antibacterial effect of styraxin against methicillin-resistant Staphylococcus aureus (MRSA), compared to antibiotics, the nanocomposite material of this invention has higher spatial resolution, less invasiveness, stronger tissue penetration, and less systemic impact on the user. Due to its unique antibacterial mechanism, the possibility of developing drug resistance is low.

[0021] (2) The self-assembled nanoparticles of erythromycin and tannic acid of the present invention have a particle size of only 30nm to 50nm, which is smaller than that of nanocomposite materials formed by loading with nanocarriers. They can reach the wound site better, effectively remove excess ROS in infected tissue, and inhibit excessive inflammation, making them convenient, quick and effective in promoting skin repair treatment.

[0022] In summary, the selection of raw materials, the design of the bonding method, and the control of particle size in this invention are all just right. They complement each other, enabling the nanomaterials of this invention to simultaneously possess good stability, dispersibility, and excellent antibacterial effects. These nanomaterials can effectively eliminate multidrug-resistant bacteria and can be applied to effectively treat skin flap wound infections induced by drug-resistant bacteria.

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

[0024] (1) The self-assembled nanoparticles of styracil and tannin provided by this invention, compared with the prior art, have the following advantages:

[0025] The spherical nanoparticles are formed by the self-assembly of squalene and tannic acid through a nanoprecipitation method. This method allows squalene and tannic acid to assemble together via hydrophobic interactions, hydrogen bonds, and other intermolecular forces, eliminating the need for a nanocarrier. The selection of raw materials and the specific bonding method enable the nanomaterial to retain its excellent antibacterial activity while improving the water solubility of squalene. Compared with existing technologies, the nanomaterial of this invention can achieve bacterial elimination at relatively low concentrations.

[0026] (2) The preparation method of the self-assembled nanoparticles of lecithin and tannic acid provided by the present invention is simple to operate, green and environmentally friendly, time-saving and easy to scale up for production and application.

[0027] (3) The self-assembled nanoparticles of strychnine and tannic acid of the present invention exert antibacterial effect in combination with strychnine and tannic acid. Compared with the prior art, the nanomaterials of the present invention have a more efficient and sustained antibacterial effect than the simple mixing of the two drugs, and can achieve the effect of eliminating bacteria in a relatively short time.

[0028] (4) The self-assembled nanoparticles of lecithin and tannic acid of the present invention significantly inhibit the generation of ROS in cells and the secretion of pro-inflammatory factors, and promote the secretion of anti-inflammatory factors, thus having good anti-inflammatory and antioxidant effects.

[0029] (5) The self-assembled nanoparticles of lecithin and tannic acid of the present invention significantly inhibit infected skin flap necrosis, rapidly clear bacteria from skin flap tissue, are safe, and have good therapeutic effects. Attached Figure Description

[0030] Figure 1Examples 1 and 2 are shown below: (A) A physical image and a laser-irradiated image of the dispersion of self-assembled nanoparticles of styraxone and tannic acid. (B) A transmission electron microscope image of the self-assembled nanoparticles of styraxone and tannic acid. (C) Particle size and zeta potential determined by dynamic light scattering (DLS). (D) Ultraviolet image of the self-assembled nanoparticles of styraxone and tannic acid. (E) Ultraviolet image and (F) Particle size diagram of the self-assembled nanoparticles of styraxone and tannic acid in buffer solutions of sodium chloride, sodium dodecyl sulfate (SDS), and urea.

[0031] Figure 2 Example 2 of the present invention (A) shows the results of treating methicillin-resistant Staphylococcus aureus with a simple mixture of vancomycin, tannic acid, styracin, styracin, and tannic acid, followed by self-assembled nanoparticles of styracin and tannic acid, with vancomycin serving as a positive control. (B) Quantitative statistical graph of colony count. (C) Growth curve of methicillin-resistant Staphylococcus aureus within 12 hours.

[0032] Figure 3 This is a scanning electron microscope image of methicillin-resistant Staphylococcus aureus after treatment with self-assembled nanoparticles of lecithin and tannic acid, as described in Example 2 of this invention.

[0033] Figure 4 The images show the confocal fluorescence pattern of ROS in (A) self-assembled nanoparticles of lecithin and tannic acid in Example 3 of this invention, and (B) fluorescence statistics.

[0034] Figure 5 The graph shows the contents of TNF-α (A), IL-1β (B), IL-6 (C), IL-4 (D), IL-10 (E), and TGF-β after treatment with lecithin and tannic acid self-assembled nanoparticles in Example 3 of this invention.

[0035] Figure 6 This is a schematic diagram of the BALB / C mouse random flap model infected with methicillin-resistant Staphylococcus aureus (MRSA) in Example 4 of this invention. (B) Random flap models of BALB / C mice infected with methicillin-resistant Staphylococcus aureus (MRSA) treated with tannic acid, styraxin, a simple mixture of styraxin and tannic acid, and styraxin and tannic acid self-assembled nanoparticles, photographs taken on days 1, 3, 5, and 7 after treatment, and a photograph of the flap tissue colonies on day 7. (C) Statistical graph of necrotic area of ​​each group of flaps. (D) Statistical graph of bacterial survival rate of each group. (E) Graph of weight change of each group of mice during treatment. (F) H&E staining and Masson staining images.

[0036] Figure 7 shows the blood routine tests for white blood cells (WBC), red blood cells (RBC), hemoglobin (HGB), and platelets (PLT) in Example 4 of the present invention. (EH) shows the blood biochemical indicators for alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea (UREA), and creatinine (CREA). (I) H&E staining of pathological sections of major organs. Figure 8 This is a schematic diagram of the synthesis of the present invention and an image abstract illustrating the wound-healing effect of the drug.

[0037] In the above figures, vancomycin is denoted as Vancomycin, tannic acid as TA, styracin as PG, a simple mixture of styracin and tannic acid is denoted as TA+PG, and self-assembled nanoparticles of styracin and tannic acid are denoted as TA@PG. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0039] Unless otherwise specified, all raw materials and instruments used in the following examples are commercially available. Concentration unit M is mol / L.

[0040] Example 1:

[0041] The present invention discloses self-assembled nanoparticles of styracin and tannic acid, wherein the nanomaterial is mainly composed of styracin and tannic acid. The particle size of the nanomaterial is in the range of 30 nm to 50 nm.

[0042] A method for preparing the self-assembled nanoparticles of styracil and tannins described in this embodiment includes the following steps:

[0043] A 2.5 mM solution of styracil in DMSO and a 0.3125 mM solution of tannic acid DMSO were mixed and stirred for 5 min. 100 μL of the mixture was then added dropwise to 900 μL of dd H₂O and sonicated for 5 min. The solution was dialyzed (MW: 3500D) for 24 h. The dialysate was centrifuged at 14000 rpm for 30 min, and the resulting precipitate was lyophilized to obtain self-assembled styracil and tannic acid nanoparticles (denoted as: TA@PG).

[0044] like Figure 1 As shown in Figure A, the self-assembled nanoparticles (TA@PG) of styracin and tannins prepared in this embodiment exhibit the Tyndall effect under laser irradiation, indicating that they have formed nanoparticles. Figure 1As shown in Figure B, the self-assembled nanoparticles (TA@PG) of styraxin and tannic acid prepared in this embodiment were analyzed by transmission electron microscopy. The results showed that uniformly dispersed spherical nanoparticles were successfully prepared. The particle size of the self-assembled nanoparticles (TA@PG) of styraxin and tannic acid was observed to be 30-50 nm by transmission electron microscopy.

[0045] The prepared styraxin and tannic acid self-assembled nanoparticles (TA@PG) were analyzed using a particle size analyzer, and the results were as follows: Figure 1 As shown in Figure C, the potential of the self-assembled nanoparticles of lecithin and tannin (TA@PG) is -25mV.

[0046] The UV absorption peaks of styraxin, tannic acid, a simple mixture of styraxin and tannic acid (TA+PG), and self-assembled nanoparticles of styraxin and tannic acid (TA@PG) were measured using a UV spectrophotometer, and the results were as follows: Figure 1 The UV peak diagram shown in D shows that the TA@PG group contains UV peaks of styracin and tannic acid, and the peaks of the simple mixture of styracin and tannic acid (TA+PG) are shifted between 500-600 nm, which indicates that styracin and tannic acid have successfully self-assembled.

[0047] The changes in the UV absorption peaks of styraxin and tannic acid self-assembled nanoparticles (TA@PG) in different buffer solutions, including sodium chloride, sodium dodecyl sulfate (SDS), and urea, were detected using a UV spectrophotometer. Figure 1 As shown in Figure E, the UV absorption peak at 284 nm of the lecithin and tannic acid self-assembled nanoparticles (TA@PG) disappeared in the three buffer solutions, indicating that the tannic acid content of the lecithin and tannic acid self-assembled nanoparticles (TA@PG) changed in the three buffer solutions. The UV peak of the lecithin and tannic acid self-assembled nanoparticles (TA@PG) changed significantly in SDS, indicating that the lecithin and tannic acid self-assembled nanoparticles (TA@PG) dissociated in SDS, and that hydrophobic interactions were the main force driving the self-assembly of lecithin and tannic acid. Simultaneously, the particle size of the lecithin and tannic acid self-assembled nanoparticles (TA@PG) changed in the three buffer solutions, further demonstrating that the main forces driving the self-assembly of lecithin and tannic acid are hydrophobic interactions, hydrogen bonds, and electrostatic interactions.

[0048] Example 2:

[0049] An application of the self-assembled nanoparticles of styracin and tannic acid (TA@PG) of the present invention in the preparation of antibacterial drugs, using the self-assembled nanoparticles of styracin and tannic acid (TA@PG) prepared in Example 1.

[0050] like Figure 2As shown in Figures AB, vancomycin was used as a positive control. 1 × 10⁷ CFU / mL of methicillin-resistant Staphylococcus aureus (MRSA) was treated for 2 hours with 5 μg / mL styraxin solution, 1 μg / mL tannic acid solution, a simple mixture of styraxin and tannic acid, and a dispersion of 5 μg / mL styraxin and tannic acid self-assembled nanoparticles (all dispersed in deionized water). The solutions were then diluted, plated, and incubated at 37°C for 8 hours. The results showed that tannic acid alone had no bactericidal effect. Styraxin alone killed 50.72% of MRSA, the simple mixture of styraxin and tannic acid killed 93.9% of MRSA, while the dispersion of styraxin and tannic acid self-assembled nanoparticles almost completely eradicated the bacteria, killing 99.8% of MRSA. Figure 3 As shown, the self-assembled nanoparticles of lecithin and tannic acid (TA@PG) completely inhibited the growth of methicillin-resistant Staphylococcus aureus within 12 hours. Figure 4 shows the morphology of bacteria treated with lecithin and tannic acid self-assembled nanoparticles under a scanning electron microscope, revealing ruptured bacterial cell membranes and distorted morphology. These results indicate that the tannic acid self-assembled nanoparticles possess a strong antibacterial effect.

[0051] Example 3:

[0052] An application of the present invention of self-assembled nanoparticles loaded with lecithin and tannic acid in scavenging reactive oxygen species and anti-inflammation, using the lecithin and tannic acid self-assembled nanoparticle dispersion prepared in Example 1.

[0053] like Figure 4 As shown, ROS fluorescence imaging was performed on the self-assembled nanoparticles (TA@PG) of sclerotin and tannins prepared in this embodiment. Human umbilical vein endothelial cell lines (HUVECs) were seeded into 24-well plates (1×10⁻⁶). 5 Cells were cultured in adherent wells for 24 h. Hydrogen peroxide (H2O2) solution (1 mM / well) was added to the culture medium and incubated for 2 h. Then, the culture medium was replaced with medium containing TA@PG NPs (TA 1 μg / mL, PG 5 μg / mL) and incubated for 4 h. The medium was then removed, 10 μM DCFH-DA probe was added, and the cells were incubated in the dark for 30 min. Imaging was performed under a confocal microscope, and statistical analysis was conducted using ImageJ software. The results showed that TA@PGNPs significantly scavenged hydrogen peroxide-induced ROS, protecting cells from hydrogen peroxide damage.

[0054] like Figure 5As shown, the effects of the self-assembled nanoparticles of styracin and tannins (TA@PG) prepared in this embodiment on the secretion of pro-inflammatory and anti-inflammatory factors by macrophages were investigated using an ELISA experiment. Macrophages (RAW264.7) were seeded into 24-well plates (1×10⁻⁶). 5 The cells / wells were cultured adherently for 24 h. The medium was then replaced with medium containing TA@PG NPs (TA 1 μg / mL, PG 5 μg / mL) and incubated for 2 h. LPS solution (100 ng / well) was then added to the medium and incubated for another 24 h. The medium was collected, and the supernatant was collected by centrifugation at 1500 rpm for 5 min. The concentrations of TNF-α, IL-1β, IL-6, IL-4, IL-10, and TGF-β in the supernatant were detected using an ELISA kit. The results showed that TA@PG NPs significantly inhibited the expression of pro-inflammatory factors such as TNF-α, IL-1β, and IL-6, and promoted the expression of anti-inflammatory factors such as IL-4, IL-10, and TGF-β, indicating the excellent anti-inflammatory activity of TA@PG NPs.

[0055] Example 4:

[0056] The application of the self-assembled nanoparticles of lecithin and tannic acid (TA@PG) of the present invention in the preparation of a skin flap treatment for methicillin-resistant Staphylococcus aureus infection, using the self-assembled nanoparticles of lecithin and tannic acid (TA@PG) prepared in Example 1.

[0057] like Figure 6 As shown in Figure A, 5 μg / mL of styraxin solution, 1 μg / mL of tannic acid solution, a simple mixture of styraxin and tannic acid, and a dispersion of 5 μg / mL styraxin and tannic acid self-assembled nanoparticles (all dispersed in PBS) were used to treat mouse skin flap wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). The results showed that the skin flaps in the control group and the tannic acid group were almost completely necrotic, while the styraxin and tannic acid self-assembled nanoparticles (TA@PG) had the lowest skin flap necrosis rate (9.48 ± 2.82%). Bacterial culture of the skin flap tissue revealed that the styraxin and tannic acid self-assembled nanoparticles (TA@PG) could rapidly clear bacteria from the tissue, with a bacterial kill rate of 99%. Figure 6 B and Figure 6 D). These results indicate that the self-assembled nanoparticles loaded with squalene and tannic acid (TA@PG) can effectively kill bacteria, inhibit skin flap necrosis, and promote skin flap repair. Biosafety evaluation in mice showed that the self-assembled nanoparticles loaded with squalene and tannic acid (TA@PG) had good biosafety. Figure 7 ).

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing self-assembled nanoparticles of styrax rubigin and tannic acid, characterized in that, Includes the following steps: S1. Dissolve styracin and tannic acid separately in dimethyl sulfoxide (DMSO) to obtain styracin DMSO solution and tannic acid DMSO solution. S2. Mix the styrax erythrin DMSO solution and the tannic acid DMSO solution at a predetermined molar ratio and stir to obtain a DMSO mixture; S3. The DMSO mixture is added dropwise to deionized water ddH2O and subjected to ultrasonic treatment to obtain a nanomaterial dispersion. S4. Dialyze the nanomaterial dispersion and collect the dialysate. The dialysate was centrifuged, the precipitate was collected and freeze-dried to obtain lecithin and tannic acid self-assembled nanoparticles.

2. The preparation method according to claim 1, characterized in that: In step S2, the molar ratio of styracin to tannic acid is 5–10:1; the molar concentration of styracin is 2.5 mM; and the stirring time is 5–10 min.

3. The preparation method according to claim 1 or 2, characterized in that: In step S3, the volume ratio of the DMSO mixture to the deionized water ddH2O is 1:9; the ultrasonic time is 5-10 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step S4, the molecular weight cutoff of the dialysis bag is 2500D to 3500D; the dialysis time is 20 to 24 hours; the centrifugation speed is 13000 rpm to 14000 rpm; and the centrifugation time is 20 to 30 minutes.

5. The self-assembled nanoparticles of styraxin and tannins prepared by the method according to any one of claims 1 to 4.

6. The self-assembled nanoparticles according to claim 5, characterized in that: The particle size of the self-assembled nanoparticles is 30 nm to 50 nm.

7. A pharmaceutical composition, characterized in that, The pharmaceutical composition comprises the self-assembled nanoparticles of claim 5 or 6 and a pharmaceutically acceptable carrier or diluent; the carrier or diluent is deionized water and / or phosphate-buffered saline (PBS).

8. Use of the self-assembled nanoparticles of claim 5 or 6 or the pharmaceutical composition of claim 7 in the preparation of antibacterial drugs.

9. Use of the self-assembled nanoparticles of claim 5 or 6 or the pharmaceutical composition of claim 7 in the preparation of a medicament for treating skin tissue infection-related damage induced by multidrug-resistant bacteria, said multidrug-resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA), said damage including MRSA-infected skin flaps and / or diabetic chronic wound infections, and said medicament for scavenging reactive oxygen species (ROS), inhibiting pro-inflammatory responses, and promoting skin tissue repair.

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