Self-assembling antibacterial peptide and use thereof

Abstract

This invention relates to the field of peptide technology, and more particularly to a self-assembled antimicrobial peptide and its applications. This invention provides a novel self-assembled antimicrobial peptide that combines potent broad-spectrum antimicrobial activity with good biocompatibility. Verification through in vivo and in vitro experiments has shown that the self-assembled antimicrobial peptide of this invention exhibits excellent antimicrobial activity against a variety of Gram-positive and Gram-negative bacteria, while also demonstrating good biocompatibility. The self-assembled antimicrobial peptide of this invention provides a new solution to address the increasingly serious challenge of antibiotic resistance, showing great application potential in the fields of antimicrobial drugs, the development of next-generation anti-infective therapies, the development of novel antimicrobial materials, and novel bactericides.

Description

Technical Field

[0001] This invention relates to the field of polypeptide technology, and more particularly to a self-assembled antimicrobial peptide and its applications. Background Technology

[0002] The overuse of antibiotics can lead to bacterial resistance, which seriously threatens human health and safety. Therefore, the development of highly effective and safe antibacterial drugs has become an urgent task.

[0003] Antimicrobial peptides typically exhibit cationic and amphiphilic structures, initially adsorbing onto negatively charged bacterial membranes via electrostatic attraction. They then insert into and disrupt the lipid bilayer through hydrophobic interactions, forming pores that lead to leakage of cell contents and bacterial death. Despite their promising prospects, the clinical translation of antimicrobial peptides faces numerous challenges. High-throughput screening is costly and time-consuming, while the vast peptide sequence space makes comprehensive screening akin to finding a needle in a haystack. Furthermore, existing antimicrobial peptides often struggle to simultaneously achieve potent, broad-spectrum antimicrobial activity and good biocompatibility.

[0004] Therefore, how to rationally design antimicrobial peptides that possess both potent and broad-spectrum antibacterial activity and good biocompatibility is a core challenge that urgently needs to be overcome in this field. Summary of the Invention

[0005] To address the aforementioned technical challenges, this invention constructs an antibacterial prediction model. A large-scale screening was conducted from a virtual library of decapeptides containing lysine, tryptophan, phenylalanine, and arginine. After in vivo verification, a self-assembled antibacterial peptide exhibiting both potent broad-spectrum antibacterial activity and good biocompatibility was ultimately obtained. Based on this, the following technical solution is proposed.

[0006] In a first aspect, the present invention provides a self-assembled antimicrobial peptide, which is R2 or K4, wherein the amino acid sequence of R2 is RRWWFFWWRR and the amino acid sequence of K4 is WKWKFFKWKW.

[0007] This invention designs the FF sequence in the center and the RWK sequence around it, screening out 6561 peptide sequences. From these 6561 peptide sequences, 10 candidate peptides with a predicted antibacterial probability score of 0.5 or higher are selected for subsequent chemical synthesis. Through screening for hemolytic activity, cytotoxicity, and antibacterial activity, self-assembled antibacterial peptides R2 and K4, possessing both potent broad-spectrum antibacterial activity and good biocompatibility, are finally obtained.

[0008] In the self-assembled antimicrobial peptides R2 and K4 of this invention, lysine and arginine provide a positive charge, facilitating initial binding to the bacterial membrane; while tryptophan and phenylalanine insert into the lipid bilayer via their hydrophobic aromatic side chains. Utilizing their hydrophobic aromatic rings to insert into the lipid bilayer, they synergistically disrupt the cell membrane.

[0009] The structural formula of the self-assembled antimicrobial peptide R2 is as follows: ; The structural formula of the self-assembled antimicrobial peptide K4 is as follows: .

[0010] Secondly, the present invention provides derivatives of the self-assembled antimicrobial peptide, which are either modified by tagging the self-assembled antimicrobial peptide, or conjugates formed by linking the self-assembled antimicrobial peptide with a carrier, or polymers formed by coupling the self-assembled antimicrobial peptide; the derivatives have the same antimicrobial function as the self-assembled antimicrobial peptide.

[0011] Thirdly, the present invention provides a nucleic acid molecule that encodes the aforementioned self-assembled antimicrobial peptide.

[0012] Fourthly, the present invention provides a peptide nanoparticle formed by the self-assembly of the aforementioned self-assembled antimicrobial peptide.

[0013] Fifthly, the present invention provides an antibacterial reagent containing the self-assembled antibacterial peptide, or containing the derivative thereof, or containing the peptide nanoparticles thereof.

[0014] In a sixth aspect, the present invention provides the application of the self-assembled antimicrobial peptide, the derivative, the nucleic acid molecule, the peptide nanoparticle, or the antimicrobial reagent in the preparation of antimicrobial products.

[0015] Preferably, the antimicrobial product is used to inhibit or kill Gram-positive and / or Gram-negative bacteria.

[0016] Preferably, the antibacterial product is used to inhibit or kill at least one of Staphylococcus aureus, Escherichia coli, Salmonella typhi, Acinetobacter baumannii, and Klebsiella pneumoniae.

[0017] In some embodiments, the antimicrobial products include, but are not limited to, antimicrobial drugs, medical disinfectants, antimicrobial medical devices (e.g., antimicrobial coated catheters / implants), antimicrobial medical materials (e.g., medical antimicrobial dressings), and antimicrobial cleaning agents (e.g., detergents, hand sanitizers, shower gels).

[0018] In a seventh aspect, the present invention provides the application of the self-assembled antimicrobial peptide, the derivative thereof, the nucleic acid molecule thereof, the peptide nanoparticle thereof, or the antimicrobial agent thereof in antimicrobial activities for non-disease diagnosis and treatment purposes.

[0019] Preferably, the application includes inhibiting or killing at least one of Staphylococcus aureus, Escherichia coli, Salmonella typhi, Acinetobacter baumannii, and Klebsiella pneumoniae.

[0020] Preferably, the staphylococcus includes at least one of Staphylococcus aureus, Staphylococcus suis, and Staphylococcus epidermidis.

[0021] Preferably, the typhoid Salmonella includes Salmonella Typhimurium.

[0022] In this invention, the inhibition refers to the inhibition of the growth and / or activity of microorganisms.

[0023] Eighthly, the present invention provides a pharmaceutical product containing the self-assembled antimicrobial peptide, or containing the derivative thereof, or containing the peptide nanoparticles thereof.

[0024] In some embodiments, the drug also includes other antimicrobial substances (e.g., antimicrobial compounds, antimicrobial extracts, etc.).

[0025] In some implementations, the pharmaceutical product also includes other pharmaceutically acceptable excipients.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a novel self-assembled antimicrobial peptide that combines potent broad-spectrum antibacterial activity with good biocompatibility. Verification through in vivo and in vitro experiments has shown that this self-assembled antimicrobial peptide exhibits excellent antibacterial activity against a variety of Gram-positive and Gram-negative bacteria, while also demonstrating good biocompatibility. This self-assembled antimicrobial peptide offers a new solution to address the increasingly serious challenge of antibiotic resistance, demonstrating significant application potential in the fields of antimicrobial drugs, the development of next-generation anti-infective therapies, the development of novel antimicrobial materials, and novel bactericides. Attached Figure Description

[0027] Figure 1 This is a high-performance liquid chromatogram of the self-assembled antimicrobial peptide R2.

[0028] Figure 2 This is a high-performance liquid chromatogram of the self-assembled antimicrobial peptide K4.

[0029] Figure 3 This is the mass spectrum of the self-assembled antimicrobial peptide R2.

[0030] Figure 4 This is the mass spectrum of the self-assembled antimicrobial peptide K4.

[0031] Figure 5 This is a graph showing the hemolysis rate of self-assembled antimicrobial peptides.

[0032] Figure 6 This is a graph showing the cell survival rate of self-assembled antimicrobial peptides.

[0033] Figure 7 This is a graph showing the hemolytic therapeutic index results of self-assembled antimicrobial peptides.

[0034] Figure 8 This is a graph showing the cytotoxicity index results of self-assembled antimicrobial peptides on HaCaT cells.

[0035] Figure 9 This is the fluorescence spectrum of the self-assembled antimicrobial peptide R2.

[0036] Figure 10 This is the fluorescence spectrum of the self-assembled antimicrobial peptide K4.

[0037] Figure 11 This is a critical micelle concentration diagram of the self-assembled antimicrobial peptide R2.

[0038] Figure 12 This is a critical micelle concentration diagram of the self-assembled antimicrobial peptide K4.

[0039] Figure 13 This is a transmission electron microscope image of the self-assembled antimicrobial peptides R2 and K4.

[0040] Figure 14 This is a transmission electron microscope image showing the morphological disruption of Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC64559 by self-assembled antimicrobial peptides R2 and K4.

[0041] Figure 15 This is a statistical graph showing the wound area of ​​mice infected with Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC 64559 after treatment with self-assembled antimicrobial peptides R2 and K4.

[0042] Figure 16 This is a statistical graph showing the bacterial load of Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC 64559-infected mouse skin wounds treated with self-assembled antimicrobial peptides R2 and K4. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] In the embodiments provided in this specification, unless specific techniques or conditions are specified, the techniques or conditions described in the literature in this field, or the product instructions, shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased from legitimate channels.

[0045] Example 1: Design and Synthesis of Self-Assembled Antimicrobial Peptides (1) A virtual library of decapeptides containing lysine, tryptophan, phenylalanine, and arginine was screened using an antibacterial prediction model. Lysine and arginine provide positive charges, which helps with the initial binding to the bacterial membrane; while tryptophan and phenylalanine insert into the lipid bilayer through their hydrophobic aromatic side chains. Their hydrophobic aromatic rings, inserted into the lipid bilayer, synergistically disrupt the cell membrane. With FF placed in the middle of the sequence and RWK placed around it, 6561 sequences were screened. Ten candidate peptides with a predicted antibacterial probability score of 0.5 or higher were then selected for subsequent chemical synthesis, as shown in Table 1. Self-assembled antimicrobial peptides R2 and K4 were obtained through screening for hemolytic activity, cytotoxicity, and antimicrobial activity. The structural formula of self-assembled antimicrobial peptide R2 is as follows: The structural formula of the self-assembled antimicrobial peptide K4 is as follows: .

[0046] Table 1

[0047] (2) The self-assembled antimicrobial peptides were synthesized using a solid-phase synthesis method via a 12-channel semi-automatic peptide synthesizer. The synthesized peptides were purified using a reverse-phase high-performance liquid chromatography (RP-HPLC) C18 column (purity >90%). ESI-MS mass spectrometry confirmed the molecular weights of the self-assembled antimicrobial peptides R2 and K4. The HPLC chromatograms of R2 and K4 are shown below. Figure 1 and Figure 2 As shown, the mass spectra of R2 and K4 are as follows: Figure 3 and Figure 4 As shown.

[0048] Example 2: Antimicrobial activity of self-assembled antimicrobial peptides The procedure for determining the minimum inhibitory concentration (MIC) of self-assembled antimicrobial peptides is as follows: (1) Single colonies of the test strain were picked into MH liquid medium, cultured overnight at 37 ℃ with shaking at 250 rpm for activation, and then transferred to MH liquid medium and cultured until the logarithmic growth phase (OD200). 600 nm = 0.4-0.6), then prepared into 10 5 Add 90 µL of CFU / mL bacterial culture to each well of a 96-well sterile cell culture plate.

[0049] (2) The self-assembled antimicrobial peptide was diluted with PBS using a 2-fold serial dilution method, with 10 µL of the self-assembled antimicrobial peptide per well, resulting in final concentrations of 128, 64, 32, 16, 8, 4, 2, 1 and 0.5 µM, respectively. The negative control group was the test bacterial culture containing the self-assembled antimicrobial peptide in PBS, and the blank control group was sterile MH medium. Each treatment had three replicates.

[0050] (3) Place the culture plate in a 37 ℃ constant temperature incubator for 16-18 h until the negative control wells show obvious turbidity of bacterial solution visible to the naked eye. The lowest concentration that can completely inhibit bacterial growth is the MIC value of the self-assembled antimicrobial peptide against the test strain.

[0051] The test strains in this embodiment include Staphylococcus aureus ATCC 43300 ( S. aureus ATCC43300 (purchased from the American Type Culture Collection), Staphylococcus aureus ACCC 61734 ( S. hyicus ACCC 61734, purchased from the China Agricultural Microbial Culture Collection Center; Staphylococcus epidermidis ATCC 12228 ( S. epidermidis ATCC12228 (purchased from the American Type Culture Collection), Escherichia coli ATCC 25922 ( E. coli ATCC 25922 (purchased from the American Type Culture Collection), Salmonella Typhimurium ATCC14028 ( S. typhimurium ATCC 14028 (purchased from the American Type Culture Collection), Acinetobacter baumannii ACCC 64559 ( A. baumannii ACCC 64559, purchased from the China Agricultural Microbial Culture Collection Center; Klebsiella pneumoniae ACCC 64561 ( k. pneumoniae ACCC 64561 (purchased from China Agricultural Microbial Culture Collection Center).

[0052] The results are shown in Table 2. The self-assembled antimicrobial peptides exhibited broad-spectrum antimicrobial activity and strong antimicrobial effects against both Gram-positive and Gram-negative bacteria.

[0053] Table 2

[0054] Example 3 Biocompatibility of self-assembled antimicrobial peptides (1) The hemolytic activity of the assembled antimicrobial peptides was assessed by measuring the amount of hemoglobin released from the lysis of mouse erythrocytes. The steps are as follows: The self-assembled antimicrobial peptide, with a final concentration of 1-128 µM, was mixed with an equal volume of 8% mouse erythrocytes, incubated at 37 °C for 1 h, centrifuged at 1500 rpm for 5 min, and the supernatant was collected. The absorbance at 540 nm was measured. 0.9% NaCl solution and 0.1% Tritalon X-100 were used as the negative and positive control groups, respectively. The hemolysis rate was calculated using the formula: Hemolysis rate = (A-A0) / (A 100 -A0)×100%.

[0055] Note: A, A0 and A100 : Represents the absorbance of the supernatant of the self-assembled antimicrobial peptide treatment group, negative control group, and positive control group, respectively.

[0056] The results are as follows Figure 5 As shown, at low concentrations, the hemolysis rate of most self-assembled antimicrobial peptide-treated groups was close to 0, indicating extremely weak erythrocyte toxicity at low concentrations. With increasing concentration to 128 μM, the hemolysis rate of some samples (especially R1, R3, K1, K3, and K5) increased, indicating erythrocyte toxicity at high concentrations. R2, R4, R5, K4, and K2 showed high hemolytic safety, while R3 and K3 exhibited relatively strong hemolytic toxicity.

[0057] (2) Activated human immortalized keratinocytes HaCaT cells at 1×10 5 Cells were seeded at a density of [cell density in mL] and cultured in 96-well plates at 37 °C with 5% CO2 for 24 h. The supernatant was removed, and the cells were washed twice with PBS. The assembled antimicrobial peptides were diluted to 1–128 µM in antibiotic-free DMEM medium, and 100 µL was added to each well of the 96-well plate and incubated for 12 h. An equal volume of 10-fold diluted CCK-8 reagent was then added and incubated for 2 h. Each treatment was repeated three times. Absorbance at 450 nm was measured using a TECAN SUNRISE microplate reader. Cell viability was calculated using the formula: Cell viability = (A / mL) * ... s -A b ) / (A c -A b ) ×100%.

[0058] Note: A s A c and A b The absorbance values ​​are for the self-assembled antimicrobial peptide treatment group, the PBS group, and the blank group, respectively.

[0059] The results are as follows Figure 6 As shown, at an incubation concentration of 128 µM, the toxicity of different treatment groups to HaCaT cells varied greatly: the cell survival rate of some treatment groups (R3, K1, K2 and K3) decreased significantly (even approaching 0), indicating significant cytotoxicity at high concentrations; while some groups (such as R2, K4 and K5) maintained high cell survival rates at higher concentrations, indicating that these self-assembled antimicrobial peptides have better safety.

[0060] (3) When the minimum hemolytic concentration measured during the experiment is greater than 64 μM, 128 μM is used to calculate the therapeutic index. If the minimum inhibitory concentration is greater than 128 μM, 256 μM is used to calculate the geometric mean of the minimum inhibitory concentration. The formula for calculating the therapeutic index is as follows: Hemolytic therapeutic index = (minimum hemolytic concentration / geometric mean of minimum inhibitory concentration) Cytotoxicity treatment index = (minimum cell viability concentration / geometric mean of minimum inhibitory concentration) The hemolytic therapeutic index results of self-assembled antimicrobial peptides are as follows: Figure 7 As shown, the cytotoxicity treatment index results for HaCaT cells are as follows: Figure 8 As shown, the self-assembled antimicrobial peptides R3, K1, K3, and K5 exhibit strong hemolytic and cytotoxic effects against HaCat, with their effective antimicrobial concentrations approaching their toxic concentrations, requiring strict dose monitoring in clinical applications. K4 (1505.75) and R4 (1189.69) have extremely high hemolytic TI values, while K5 has the highest cytotoxic therapeutic index against HaCaT cells (TI=51.32), followed by K1 (40.93), R2 (36.80), and K4 (33.65).

[0061] In summary, the self-assembled antimicrobial peptides R2 and K4 exhibit the best overall performance spectrum, demonstrating strong inhibitory effects on a variety of pathogens, including drug-resistant bacteria, while also showing good biocompatibility.

[0062] Example 4: Fluorescence spectra of self-assembled antimicrobial peptides R2 and K4 1,8-ANS fluorescent probe is a fluorescent dye with high affinity for hydrophobic protein surfaces, used to detect the self-assembly ability of self-assembled antimicrobial peptides. Different concentrations of self-assembled antimicrobial peptides R2 and K4 (final concentration 1-256 µM) were diluted with PBS and mixed with the fluorescent probe 1,8-ANS (final concentration 25.6 µM) at a 1:1 volume ratio, and incubated for 1 h. The fluorescence spectra of the self-assembled antimicrobial peptides R2 and K4 were measured using a microplate reader, with excitation wavelength at 360 nm and emission wavelength at 400-670 nm.

[0063] The results are as follows Figure 9 and Figure 10 As shown, the fluorescence intensity at 480 nm increases significantly with the increase of R2 and K4 concentrations. This is because the self-assembly of R2 and K4 significantly increases the hydrophobic environment, thereby significantly increasing the fluorescence intensity of 1,8-ANS.

[0064] Critical micelle concentrations of self-assembled antimicrobial peptides R2 and K4, such as Figure 11 and Figure 12 As shown, the critical micelle concentration of R2 is 15.82 µM, and the critical micelle concentration of R2 is 25.06 µM, indicating strong self-assembly ability.

[0065] Example 5: Transmission electron microscopy characterization of the self-assembled structures of antimicrobial peptides R2 and K4. 10 µL of self-assembled antimicrobial peptides R2 and K4 (80 µM, water as solvent) were dropped onto a 100-mesh copper-plated grid and precipitated for 10 min. The residual liquid was adsorbed onto filter paper, stained with 3% uranium acetate for 1 min, rinsed three times with ultrapure water, dried, and observed under a transmission electron microscope (Tecnai Spirit, FEI).

[0066] The results are as follows Figure 13 As shown, the self-assembled antimicrobial peptides R2 and K4 self-assemble to form nanoparticles.

[0067] Example 6: Transmission electron microscopy observation of the morphological disruption of Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC 64559 by self-assembled antimicrobial peptides R2 and K4. The bacteria in the logarithmic growth phase were centrifuged (4000 rpm, 5 min), washed three times with PBS solution, and diluted to the desired concentration (1 × 10⁻⁶). 9 (CFU / mL). Self-assembled antimicrobial peptides R2 and K4, at a final concentration of 80 µM, were incubated with *Staphylococcus aureus* ATCC 43300 and *Acinetobacter baumannii* ACCC 64559 for 2 h. After washing three times with PBS, the samples were fixed with 2% osmium tetroxide for 1.5 h. Gradual dehydration was performed using 50%, 70%, and 90% ethanol, and pure ethanol for 8 min, followed by dehydration in pure ethanol for 10 min. Fixation was then continued in a 1:1 volume ratio of pure ethanol and acetone for 10 min, and finally in pure acetone for 10 min. The samples were then embedded in resin overnight. Sectioning and staining were performed using a transmission electron microscope (Hitachi HT-7700, Japan) for observation.

[0068] The results are as follows Figure 14 As shown, after self-assembled antimicrobial peptides R2 and K4 acted on Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC 64559, Staphylococcus aureus ATCC 43300 and Acinetobacter baumannii ACCC 64559 showed severe cell membrane damage.

[0069] Example 7: In vivo efficacy study of self-assembled antimicrobial peptides R2 and K4 Ninety 6-week-old BALb / c mice (SPF grade) were randomly divided into 9 groups: (1) Blank control group (uninfected group, BC), (2) Staphylococcus aureus ATCC 43300 negative control group (infected but untreated group, PBS), (3) Acinetobacter baumannii ACCC64559 negative control group (infected but untreated group, PBS), (4) Staphylococcus aureus ATCC 43300 test group R2 (7.5 mM), (5) Staphylococcus aureus ATCC 43300 test group K4 (7.5 mM), (6) Staphylococcus aureus ATCC 43300 treatment group mupirocin ointment (0.6 mg, MUP antibiotic group), (7) Acinetobacter baumannii ACCC 64559 test group R2 (7.5 mM), (8) Acinetobacter baumannii ACCC 64559 test group K4 (7.5 mM), (9) Acinetobacter baumannii ACCC 64559 treatment group polymyxin ointment (0.6 mg, PB antibiotic group).

[0070] Mice were anesthetized, and the shaved skin was wiped with 70% alcohol swabs. Using sterile forceps and scissors, a 1 cm diameter circular incision was made on the mouse's back, removing the entire skin layer down to the mucous membrane layer. Then, 100 µL of bacterial suspension (Staphylococcus aureus ATCC 43300 at 1×10⁻⁶) was added. 8 CFU / mL, Acinetobacter baumannii ACCC 64559 is 5 × 10 4 CFU / mL was applied to the wound of each mouse, and the wound was bandaged with sterile gauze and tape. The wound was treated with the corresponding drugs according to the group (administered for 7 consecutive days, once a day, with the concentration of each administration as described above for the grouping, and 50 μL each time for the experimental group).

[0071] On days 7 and 14 after treatment, mice were euthanized by dislocation, fixed and dissected, and the skin tissue was aseptically separated, weighed, and homogenized in PBS (50 Hz, 20 min). The homogenate was then serially diluted and plate counts were performed.

[0072] The results of the wound area are as follows Figure 15 As shown, the R2 / K4 treatment group healed faster: the healing rate was approximately 40% on day 3 and nearly 90% on day 14. Regardless of whether the infection was Staphylococcus aureus ATCC 43300 or Acinetobacter baumannii ACCC 64559, the wound area in this group was significantly smaller than other groups at all time points (especially after day 7), superior to the MUP / PB antibiotic group. The untreated group and the blank control group healed the slowest.

[0073] Results of bacterial load on skin wounds as follows Figure 16As shown, the bacterial load of R2 / K4 was significantly reduced: the bacterial count (logarithmic value) on days 7 and 14 was much lower than that in the untreated group and the blank control group, indicating that the antibacterial effect of R2 / K4 effectively cleared bacteria from the wound. The untreated group (PBS treatment) had a higher bacterial load, and the bacterial count on days 7 and 14 remained at a high level (logarithmic value close to 7-10), indicating that treatment without antibacterial effect could not effectively control the infection.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-assembling antimicrobial peptide, characterized in that, It is either R2 or K4. The amino acid sequence of R2 is RRWWFFWWRR, and the amino acid sequence of K4 is WKWKFFKWKW.

2. The self-assembling antimicrobial peptide of claim 1, wherein, The structural formula for R2 is as follows: ； The structural formula for K4 is as follows: 。 3. A nucleic acid molecule, characterized in that, It encodes the self-assembled antimicrobial peptide as described in claim 1.

4. A peptide nanoparticle characterized in that, It is formed by the self-assembly of the self-assembled antimicrobial peptide as described in claim 1 or claim 2.

5. An antibacterial reagent, characterized in that, It contains the self-assembled antimicrobial peptide as described in claim 1 or claim 2, or it contains the peptide nanoparticles as described in claim 4.

6. The application of the self-assembled antimicrobial peptide of claim 1 or claim 2, the nucleic acid molecule of claim 3, the peptide nanoparticle of claim 4, or the antimicrobial reagent of claim 5 in the preparation of antimicrobial products; wherein the antimicrobial products are used to inhibit or kill at least one of Staphylococcus aureus, Escherichia coli, Salmonella typhi, Acinetobacter baumannii, and Klebsiella pneumoniae.

7. The application of the self-assembled antimicrobial peptide of claim 1 or claim 2, the nucleic acid molecule of claim 3, the peptide nanoparticle of claim 4, or the antimicrobial reagent of claim 5 in antimicrobial treatment for non-disease diagnosis and treatment purposes; wherein the antimicrobial effect is the inhibition or killing of at least one of Staphylococcus aureus, Escherichia coli, Salmonella typhi, Acinetobacter baumannii, and Klebsiella pneumoniae.

8. A medicine, characterized in that, It contains the self-assembled antimicrobial peptide of claim 1 or claim 2, or contains the peptide nanoparticles of claim 4.

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