Fluorinated polypropyleneimine cationic antibacterial agent as well as preparation method and application thereof

Abstract

The invention discloses a fluorinated polypropylene imine (F-PPI) cationic antibacterial agent as well as a preparation method and application thereof. According to the method, F-PPI with adjustable molecular weight is synthesized on the basis of a 2-propyl oxazine monomer. The chemical structure is clear, the molecular weight is uniform and controllable, the fluorinated group is located at the head end of PPI, the controllable degree is high, and the process repeatability and the batch stability are high. The antibacterial efficiency of the cationic polymer can be improved by fluorinated groups and main chain amino cations, and the cationic polymer is endowed with better antibacterial selectivity and biocompatibility according to the characteristics of fluorine elements. End group fluorination modification is carried out in the polymerization process of linear polypropylene imine, and high hydrophobicity and biological inertness of fluoride can be combined, so that the cationic antibacterial agent with low cytotoxicity and high antibacterial efficiency is obtained. The method is simple and convenient in synthesis process, has high repeatability, and is beneficial to construction of high-efficiency and low-toxicity cationic polymers.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical polymer materials, and particularly relates to a fluorinated polypropyleneimine PPI cationic antibacterial agent and its preparation method and application. Background Art

[0002] Cationic antibacterial agents are a class of materials that achieve antibacterial effects through the interaction between cationic groups (carrying positive charges) and the negative charges of microbial cell membranes. Due to their high efficiency, broad spectrum, and unique mechanism of action, such antibacterial agents are widely used in fields such as medicine, food, textiles, agriculture, and environmental protection. Bacterial cell membranes are rich in negatively charged molecules, such as lipopolysaccharides of Gram-negative bacteria and teichoic acids of Gram-positive bacteria, which provide targets for cationic antibacterial agents. Through electrostatic adsorption, cationic antibacterial agents can disrupt the integrity of the cell membrane, causing increased membrane permeability, leakage of intracellular contents, and membrane potential disorders, thereby leading to cell death. In addition, some cationic antibacterial agents can also interfere with intracellular metabolic activities or induce the generation of reactive oxygen species (ROS), further enhancing the bactericidal effect. According to their chemical structures and functional characteristics, cationic antibacterial agents can be divided into various types, including quaternary ammonium salts (such as benzalkonium chloride), guanidine compounds (such as polyhexamethylene biguanide), cationic polymers (such as polyethyleneimine and polypropyleneimine), cationic surfactants, and nanomaterials with cationic groups on their surfaces (such as gold nanoparticles and graphene oxide). The advantage of cationic antibacterial agents lies in that their mechanism of action is mainly physical destruction, reducing the possibility of the generation of microbial drug resistance, and they also have rapid and efficient bactericidal capabilities. However, such antibacterial agents also face some challenges. The potential toxicity of cationic materials and their impact on the environment remain the main challenges. For example, their potential toxicity to mammalian cells, poor environmental degradability, and insufficient antibacterial selectivity. Therefore, the research focus in recent years has included optimizing the charge density, introducing biodegradable groups, and developing composite materials to improve their biocompatibility and environmental friendliness. Future research directions include developing materials with higher selectivity and biocompatibility, and combining cationic antibacterial agents with other antibacterial mechanisms to address the threat of multi-drug resistant bacteria. In terms of biocompatibility, fluorine atoms reduce the toxicity of cationic polymers. After introducing fluorine atoms into the PPI molecule, they will partially replace or shield the positive charge density of its protonated amino groups. Since PPI with a high positive charge density easily undergoes strong non-specific interactions with cell membranes (especially mammalian cell membranes), resulting in membrane damage and cytotoxicity, this interaction is significantly reduced after fluorination. Moreover, fluorination modification improves the amphiphilicity of the PPI molecule, making it more hydrophobic, and can regulate the interaction between the polymer and the cell membrane. Compared with traditional PPI, F-PPI interacts more gently with the membranes of human cells, making its destructive effect on bacterial cell membranes more effective while causing less interference to mammalian cells, thus reducing toxicity.

[0003] Polypropyleneimine (PPI) cation is a material with good antibacterial properties. The polypropyleneimine molecule contains a large number of cations (amino groups), and these cations can interact with the anionic part of the bacterial cell membrane. Since the surface of the bacterial membrane is usually negatively charged, the cations of polypropyleneimine can undergo electrostatic attraction with the negatively charged part of the bacterial cell membrane, breaking the integrity of the cell membrane, resulting in the leakage of cell contents, and ultimately causing bacterial death. The cationic properties of polypropyleneimine not only promote adsorption to the bacterial membrane but may also cause physical damage to the membrane. The polypropyleneimine molecule can form pores or disrupt the structure of the membrane through interaction with the cell membrane, leading to an imbalance in the internal and external environments of the cell and ultimately killing the bacteria. Polypropyleneimine exhibits antibacterial activity against a variety of bacteria, including Gram-negative and Gram-positive bacteria, which makes it promising in a variety of applications, especially in antibacterial coatings and medical devices. Different from some traditional antibacterial agents, polypropyleneimine has relatively low toxicity, so it can be used in some applications with higher requirements, such as the biomedical field.

[0004] Unmodified PPI has certain antibacterial properties, but due to the hydrophilic structure of its amino groups, its binding to the bacterial cell membrane is not tight enough. And due to its high cation density, it has certain biological toxicity to normal biological cells. Therefore, it is an urgent need to develop cationic polymer antibacterial agents with more tightly bound membrane-binding efficiency and lower cytotoxicity.

[0005] Compared with unfluorinated polypropyleneimine (PPI), in terms of antibacterial performance, after fluorination, polypropyleneimine introduces highly hydrophobic fluorine groups (such as -CF3- or -CF2-), enhancing its ability to interact with the lipid bilayer of the bacterial cell membrane. The hydrophobic components of the bacterial cell membrane are more easily damaged by fluorinated molecules, thus improving the antibacterial effect. And fluorinated polypropyleneimine may show better bactericidal effects against some pathogens with stronger resistance (such as biofilm-forming bacteria). In terms of physical properties, fluorine has extremely low reactivity and high chemical stability, making fluorinated PPI not easily degraded in harsh chemical environments. And the polyfluorine groups increase the thermal stability of the material, enabling it to maintain the stability of its structure and properties even in high-temperature environments.

[0006] Many existing cationic antimicrobials (such as quaternary ammonium salts and cationic polymers) may have certain toxicity to mammalian cells while having high antibacterial efficiency, which limits their application in the biomedical field. Some cationic antibacterial agents are easily degraded or inactivated in the environment, resulting in a decrease in antibacterial performance, especially under high-salt or high-temperature conditions. Some cationic antibacterial agents have weak effects on certain specific types of bacteria or fungi and are difficult to cope with complex multi-species environments. And the long-term use of cationic antibacterial agents may lead to bacteria developing tolerance, for example, by changing the cell membrane surface charge or secreting protective substances, reducing their antibacterial effect. Summary of the Invention

[0007] Based on the problems pointed out in the background art, the present invention aims to provide a fluorinated polypropyleneimine (F-PPI) cationic antibacterial agent and its preparation method and application.

[0008] To achieve the above object, according to one aspect of the present invention, there is provided a fluorinated polypropyleneimine (F-PPI) having the following structure shown in formula (Ⅰ):

[0009] Formula (Ⅰ) Wherein, 0 ≤ n ≤ 7, 0 ≤ m ≤ 3, 10 ≤ p ≤ 500. Preferably, 10 ≤ p ≤ 100.

[0010] To achieve the above object, according to one aspect of the present invention, there is provided a preparation method of the above F-PPI, comprising the following steps: A. Reflux and heat butyronitrile and propanolamine under the catalysis of zinc acetate. After the product is dissolved in a solvent (dichloromethane or ethyl acetate), water is added for extraction to ensure complete removal of propanolamine. Take the lower organic layer, add anhydrous MgSO4 for drying, filter, and take the filtrate for rotary evaporation to obtain 2-propyl-2-oxazine monomer. The rotary-evaporated 2-propyl-2-oxazine monomer is dehydrated by vacuum distillation, the pure fraction is collected, and after adding anhydrous magnesium sulfate, a completely dry 2-propyl-2-oxazine monomer is obtained. Wherein, the molar ratio of butyronitrile to propanolamine is 1:1 to 1.2; the reaction conditions for the reflux and heating are to slowly react at 110°C - 150°C for 2 - 4 days, preferably to slowly react at 120 - 130°C for 2 - 3 days.

[0011] The rotary evaporation is to first distill out DCM at room temperature, then raise the temperature to 35 - 55°C to distill out most of the butyronitrile to obtain a crude product of 2-propyl-2-oxazine monomer.

[0012] The dehydration by vacuum distillation: The crude monomer product is vacuum distilled until no liquid drips out, the temperature is raised to 80°C, observed for 20 minutes to ensure no butyronitrile is distilled out, the temperature is raised to 100°C, the first 2 mL of liquid is discarded, the flask is changed, the temperature is raised to 120°C, and the pure fraction is collected.

[0013] B. Dissolve the dry 2-propyl-2-oxazine and the fluorinated polyalkyl initiator in a solvent (acetonitrile, chlorobenzene or dichlorobenzene), react in a closed container, and after the reaction, dissolve it in a benign solvent (dichloromethane, ethyl acetate, ethanol, etc.) and transfer it to a reaction flask. Rotavaporize to remove the residual solvent at a temperature of 30°C to 70°C to obtain a poly(2-propyl-2-oxazine) with fluorinated end groups, and its structural formula is shown in the following formula (II):

[0014] Formula (II) C. Add hydrochloric acid for reaction. After the reaction, precipitate in a precipitation solvent, wash, and dry to obtain F-PPI.

[0015] Among them, the concentration of the hydrochloric acid is 6 to 12 mol / L; the reaction temperature is 60 to 100°C; the reaction time is 48 to 96 h; the precipitation solvent includes one or more of methanol, ethanol, ether, and acetone, and it is pre-cooled in an ice-water bath before use, and the cooling time in the ice-water bath is not less than 15 min; the drying is drying in a vacuum oven until the product is in the form of a white powder.

[0016] In order to achieve the invention object of the present invention, on the other hand, the present invention provides the application of the fluorinated polypropylene imine (F-PPI) shown in formula (I) in antibacterial aspects. For example, the F-PPI shown in formula (I) is used as an antibacterial active ingredient for preparing antibacterial coatings, biomedical materials, or drug delivery carriers.

[0017] In one or more embodiments of the present invention, 1H,1H,2H,2H-perfluoro-1-decanol, 1,1,2,2-tetrahydroperfluorohexyl iodide, and 3,3,4,4,4-pentafluoro-1-iodobutane are respectively used as different polyfluoroalkyl initiators to analyze the antibacterial results of different fluorinated end-group F-PPIs, and it is proved that the antibacterial effect of low fluorination degree is better. In one or more embodiments of the present invention, F-PPIs with the same fluorination degree and monomer polymerization degrees of 10, 20, and 50 are respectively synthesized to analyze the antibacterial results of different polymerization degree F-PPIs, and it is proved that the antibacterial effect of high polymerization degree is better.

[0018] Based on the 2-propyl oxazine monomer, the present invention synthesizes F-PPI with adjustable molecular weight, with a clear chemical structure, uniform and controllable molecular weight, the fluorinated group is located at the head of PPI, with a high controllability degree, and high process repeatability and batch stability. Both the fluorinated group and the main chain amino cation can improve the antibacterial efficiency of the cationic polymer of the present invention, and endow it with better antibacterial selectivity and biocompatibility according to the characteristics of fluorine elements.

[0019] Based on linear polyethyleneimine (LPEI), this invention adds a carbon atom to turn it into linear polypropyleneimine (LPPI), and on this basis, conducts fluorination modification on it to synthesize a cationic antibacterial agent with excellent antibacterial performance, low cytotoxicity, and high biocompatibility. Linear polypropyleneimine (LPPI) can disrupt the bacterial cell membrane through electrostatic interaction. LPPI contains a large number of protonated amino groups and carries a positive charge under physiological conditions. These positive charges can strongly adsorb the negatively charged components on the bacterial surface, such as lipopolysaccharide of Gram-negative bacteria and teichoic acid of Gram-positive bacteria. At the same time, electrostatic adsorption will lead to disordered charge distribution on the surface of the bacterial cell membrane, damage the membrane integrity, increase its permeability, and thus cause the leakage of cell contents. When the adsorption force is strong enough, LPPI can directly damage the structural integrity of the cell membrane, causing irreversible membrane damage. On this basis, the end-group fluorination modification of LPPI generates fluorinated polypropyleneimine (F-PPI). Due to the high lipophilicity of fluorine atoms, the hydrophobic interaction between F-PPI and the cell membrane is enhanced, enabling it to form a tight binding with the fatty acid tails of the cell membrane through hydrophobic interaction, thereby enhancing the adsorption force. The strong covalent property and low polarizability of the fluorocarbon bond also contribute to more stable insertion and binding to the cell membrane, further enhancing the ability to attach to the membrane. For the interior of the cell, the cationic property of F-PPI makes it easy to bind to DNA or RNA inside the cell after entering, interfering with the function of nucleic acids and inhibiting gene transcription and protein synthesis. F-PPI may also interact with the proteins of bacteria, especially with key enzymes, thus affecting the normal metabolism and physiological functions of bacteria.

[0020] This invention uses polyfluoroalkyl to conduct fluorination modification on PPI to prepare the F-PPI cationic polymer antibacterial agent. The introduced fluorine atoms reduce the toxicity of the cationic polymer, improve the hydrophobicity and balance of hydrophilicity and hydrophobicity of the compound, reduce the non-specific interaction with human cells, and at the same time improve the high antibacterial activity against bacterial cells. This molecular design greatly improves the biocompatibility of F-PPI, making it have a broader application prospect in the fields of antibacterial coatings, biomedical materials, and drug delivery. Description of the Drawings

[0021] Figure 1 1H NMR data of the 2-propyl oxazine monomer prepared in Example 1.

[0022] Figure 2 GPC data for characterizing the molecular weight of the PPI and F-PPI cationic polymers prepared in this invention.

[0023] Figure 3 1H NMR data of poly(2-propyl)oxazine with intermediate polymer 10.

[0024] Figure 4 1H NMR data of poly(2-propyl)oxazine with intermediate polymer of 20.

[0025] Figure 5 1H NMR data of poly(2-propyl)oxazine with intermediate polymer of 50.

[0026] Figure 6 1H NMR data of pentafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0027] Figure 7 19F NMR data of pentafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0028] Figure 8 1H NMR data of nonafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0029] Figure 9 19F NMR data of nonafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0030] Figure 10 1H NMR data of heptadecafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0031] Figure 11 19F NMR data of heptadecafluoropoly(2-propyl)oxazine with intermediate polymer of 50.

[0032] Figure 12 1H NMR spectrum of 5F-PPI50.

[0033] Figure 13 1H NMR spectrum of 9F-PPI50.

[0034] Figure 14 1H NMR spectrum of 17F-PPI50.

[0035] Figure 15 Antibacterial effect diagrams of the F-PPI cationic polymer antibacterial agent prepared in the present invention and the PPI control group against Staphylococcus aureus S. aureus.

[0036] Figure 16 Antibacterial effect diagrams of the F-PPI cationic polymer antibacterial agent prepared in the present invention and the PPI control group against Escherichia coli E.col.

[0037] Figure 17 Antibacterial effect diagrams of the F-PPI cationic polymer antibacterial agent prepared in the present invention and the PPI control group against methicillin-resistant Staphylococcus aureus MRSA.

[0038] Figure 18Hemolysis test chart of the F-PPI cationic polymer antibacterial agent prepared by the present invention and the PPI control group on mouse blood.

[0039] Figure 19 Test chart of the cytotoxicity of the 50-degree polymerization F-PPI cationic polymer antibacterial agent prepared by the present invention and the PPI control group.

[0040] Figure 20 Curve of the effect of the 5F-PPI50 cationic polymer antibacterial agent prepared by the present invention on Escherichia coli changing with time.

[0041] Figure 21 SEM chart of the morphological changes of bacteria before and after co-culture with the 5F-PPI50 cationic polymer antibacterial agent prepared by the present invention. Detailed implementation manners

[0042] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] The present invention provides a synthesis method of fluorinated polypropyleneimine (F-PPI) in the following embodiments, and its synthesis route is as follows: Example 1

[0044] Preparation of 2-propyl-2-oxazine monomer: Add 2 mol of butyronitrile and 2 mol of propanolamine into a three-necked flask, reflux and heat under the catalysis of zinc acetate, slowly react at 110°C - 150°C for 2 - 4 days, dissolve the product in CH2Cl2, extract with 150 mL of water for 6 times to ensure complete removal of propanolamine. Take the lower organic layer, dry it with anhydrous MgSO4, filter, take the filtrate and rotary evaporate. Control the rotary evaporation temperature. First, distill out DCM at room temperature, then raise the temperature to 35 - 55°C to distill out most of the butyronitrile to obtain a crude product of 2-propyl-2-oxazine monomer. Then, vacuum distill the crude monomer until no liquid drips out, raise the temperature to 80°C, observe for 20 minutes to ensure no butyronitrile is distilled out, raise the temperature to 100°C, discard the first 2 mL of liquid, change the flask, raise the temperature to 120°C, and collect the pure fraction to obtain the 2-propyl-2-oxazine monomer after water removal, with a yield of 96%. The nuclear magnetic resonance hydrogen spectrum of the prepared 2-propyl oxazine monomer is shown in Figure 1 . Example 2

[0045] In this example, 2-propyl-2-oxazine monomer was used as the substrate and methyl p-toluenesulfonate was used as the initiator. Polypropyleneimine with different degrees of polymerization was prepared by controlling the molar ratio of the initiator to the monomer (1:5 - 50), and was labeled as PPIm (m = 5, 10, 20, 50). The specific preparation method is as follows: (1) Take 0.0764 mol of 2-propyl-2-oxazine in a synthesis flask, take methyl p-toluenesulfonate as the initiator, take 10 ml of acetonitrile as the solvent, and stir at 85 °C for 24 - 48 h to obtain poly(2-propyl)oxazine with different degrees of polymerization; (2) Rotavaporize the obtained poly(2-propyl)oxazine at 70 °C to remove the solvent acetonitrile. Hydrolyze the rotavapor-purified poly(2-propyl)oxazine with 6 mol / L hydrochloric acid at 100 °C for 72 h to obtain polypropyleneimine; (3) Precipitate the hydrolyzed product with acetone, filter by suction, spin dry, and vacuum dry to obtain polypropyleneimine with different degrees of polymerization, which is a white solid powder. The yields of polypropyleneimine of different polymers are shown in Table 1. Figures 3 - 5 1H NMR data of the intermediate poly(2-propyl)oxazine.

[0046] Table 1 Yields of polypropyleneimine with different degrees of polymerization . Example 3

[0047] In this example, 2-propyl-2-oxazine monomer was reacted with a fluorinated polyalkyl initiator. Terminal fluorinated polypropyleneimine with different degrees of polymerization was prepared by controlling the molar ratio of the initiator to the monomer (1:10 - 50), and was labeled as xF-PPIm (x represents the number of fluorine atoms in the molecule, and m represents the degree of polymerization). The preparation method is the same as that in Example 2.

[0048] Table 2 Yields of fluorinated polypropyleneimine with different degrees of polymerization . Example 4

[0049] Antibacterial tests (against Escherichia coli, Staphylococcus aureus, and drug-resistant bacteria) were carried out on the synthesized polypropyleneimine (PPI) and fluorinated PPI with different degrees of polymerization: 1. Streak inoculate from glycerol strains (Staphylococcus aureus (S. aureus), Escherichia coli (E. col), methicillin-resistant Staphylococcus aureus (MRSA) (frozen and stored at -80 °C)) onto MHA agar plates and incubate at 37 °C for 18 - 24 hours until the colonies grow completely.

[0050] 2. Preparation of bacterial suspension: Pick a single colony and inoculate it into 5 mL of MHB medium. Incubate with shaking at 37°C for 4 - 6 hours until the logarithmic growth phase (OD600 ≈ 0.5, equivalent to 1.5×10 8 CFU / mL). Dilute it to 5×10 5 CFU / mL (the standard concentration for MIC experiment) with normal saline (0.9% NaCl). Then, in a sterile 96-well plate, add 100 μL of MHB to each well. Add 100 μL of F-PPI (32 μg / mL) to the first column, and then perform a two-fold serial dilution to the 7th column (16 μg / mL, 8 μg / mL, 4 μg / mL, 2 μg / mL, 1 μg / mL, 0.5 μg / mL). The 8th column is the blank control (without antibacterial agent). Set 3 replicates for each concentration. Add 100 μL of the bacterial suspension (5×10 5 CFU / mL) to each well, and the final volume is 200 μL. (Positive control group: containing only bacteria without antibacterial agent. Take 100 μL of the culture solution from each well (i.e., the F-PPI treatment groups with different concentrations) and spread it onto MHA agar plates with a sterile spreading rod (set 3 parallel samples for each concentration). Incubate the plates in an incubator at 37°C for 18 - 24 hours until bacterial colonies form. Observe the colony growth in each group, calculate the total number of colonies (CFU, Colony-Forming Unit) on each agar plate. Count the number of colonies and calculate the survival rate relative to the positive control (the group without antibacterial agent).

[0051] The test results are as Figure 15 , 16, 17. Analyzing the antibacterial experiment results of Staphylococcus aureus, it is concluded that in the case of without fluorine, the antibacterial performance of high-polymerization-degree PPI is better than that of low-polymerization-degree PPI. After fluorination, the antibacterial performance of PPI is better than that of non-fluorinated PPI, and the high-polymerization-degree fluorinated PPI is better than the low-polymerization-degree one. The antibacterial performance of low-fluorination-degree is better than that of high-fluorination-degree. The same conclusion is drawn for the experiments on Escherichia coli and drug-resistant bacteria. Example 5

[0052] Perform hemolysis tests on the synthesized PPI with different polymerization degrees and fluorinated PPI: 1. Red blood cell separation: Take mouse anticoagulated blood (3 mL), centrifuge at 400 g for 5 min, and discard the supernatant. Wash it 3 times with PBS and resuspend it to a 10% red blood cell suspension.

[0053] 2. Hemolysis experiment: Take 100 μL of red blood cell suspension into a 96-well plate, and add 100 μL of 320 - 10 μL / ml F-PPI (different concentrations) to each well in the order of concentration gradient. Set the normal saline group (0% hemolysis) and the deionized water group (100% hemolysis) as controls. Incubate at 37°C for 1 h, then centrifuge at 1000g for 3 min, and take the supernatant. Measure the absorbance (OD value) at 540 nm with a spectrophotometer.

[0054] The test results are as Figure 18 , and it can be seen from analyzing the hemolysis test chart that compared with unfluorinated PPI50, at the effective antibacterial concentration, the hemolysis rate has no obvious change and remains within 5%. Example 6

[0055] Perform cytotoxicity tests on the synthesized PPI with different degrees of polymerization and fluorinated PPI: Inoculate B16F10 cells into a 96-well plate at a density of 1 × 10 4 cells / well. Culture the cells in DMEM medium containing 10% fetal bovine serum (FBS) and 1% penicillin-streptomycin at 37°C and 5% CO2 for 24 hours until the cells grow to the logarithmic growth phase.

[0056] 1. Treatment group: Add the F-PPI solution to the 96-well plate at different concentrations (decreasing sequentially from 320 μg / mL), and the final concentration is 10 μL solution / 100 μL medium.

[0057] 2. Control group: Add the same volume of solvent (such as PBS or deionized water) as the control group. After incubating for 24 hours, add 10 μL of MTT (5 mg / mL) to each well and continue to incubate at 37°C for 4 hours. Aspirate the medium, add 150 μL of DMSO (to dissolve the formazan crystals). Gently shake for 10 min to completely dissolve the purple product. Measure the absorbance (OD value) at 570 nm with an ELISA plate reader.

[0058] The test results are as Figure 19 , and it can be concluded from analyzing the cytotoxicity results that the cytotoxicity of high-fluorination degree is higher than that of low-fluorination degree, and at the effective antibacterial concentration, fluorinated PPI does not show obvious cytotoxicity. Example 7

[0059] Perform a test on the change of antibacterial effect of the synthesized fluorinated PPI over time: 1. Bacterial suspension preparation: Take Escherichia coli (E. coli) from the glycerol strain, streak inoculate it onto an MHA agar plate, and incubate at 37°C for 18 - 24 hours until the colonies grow completely. Pick a single colony and inoculate it into 5 mL of MHB medium, shake culture at 37°C for 4 - 6 hours until the logarithmic growth phase (OD600 ≈ 0.5, equivalent to 1.5×10 8 CFU / mL).

[0060] Dilute it to 5×10 5 CFU / mL with normal saline (0.9% NaCl).

[0061] 2. Experimental setup: Culture 20 ml of bacterial solution with a concentration of 5×10 5 CFU / mL in a 50 ml centrifuge tube, add a certain concentration of the bacterial solution, and then take 1 ml of the bacterial solution every 30 minutes for ultraviolet OD600 absorbance measurement, and calculate the bacterial colony concentration according to the corresponding absorbance.

[0062] The test results are as Figure 20 , and it can be seen that around 30 minutes, the bacterial growth was significantly inhibited, and after 60 minutes, there was no obvious growth of the colonies, indicating that fluorinated PPI can take effect immediately on bacteria and has excellent antibacterial effects. Example 8

[0063] Use a scanning electron microscope (SEM) to observe the microscopic morphological changes of S. aurus and E. coli before and after the action of F-PPI. Take S. aureus and E. coli in an EP tube, centrifuge and enrich them, incubate with a certain concentration of F-PPI at 37°C for 30 minutes, centrifuge and take the precipitate, wash it several times with PBS, centrifuge, discard the supernatant, add 200 μL of 4% glutaraldehyde solution to the precipitate, let it stand in the dark for 2 hours, centrifuge at 5000 rpm and 4°C for 5 minutes, remove the supernatant, add 1 ml of 50% ethanol solution, pipette evenly, dehydrate for 10 minutes, centrifuge again, and then sequentially dehydrate with 70%, 90%, and 100% ethanol solutions, wash with PBS, take 10 drops and add them to a clean silicon wafer placed in a 6-well plate and let it air dry overnight, and observe with a scanning electron microscope.

[0064] The test results are as Figure 21 , and it can be observed that after the treatment with F-PPI, compared with normal bacteria, its surface membrane is severely damaged, indicating that the drug mainly acts on the surface of bacteria and kills bacteria by disrupting the bacterial membrane structure.

[0065] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A fluorinated polypropylene imine, the structure of which is shown in the following formula (Ⅰ): ， Formula (Ⅰ) Among them, 0 ≤ n ≤ 7, 0 ≤ m ≤ 3, 10 ≤ p ≤ 500.

2. The fluorinated polypropylene imine according to claim 1, wherein 10≤p≤100。 3. The preparation method of the fluorinated polypropylene imine according to claim 1 or 2, characterized in that, It includes the following steps: A. Reflux and heat the reaction of butyronitrile and propanolamine under the catalysis of zinc acetate. After the product is extracted and dried, a completely dry 2-propyl-2-oxazine monomer is obtained; B. Dissolve the dry 2-propyl-2-oxazine and a fluorinated polyalkyl initiator in a solvent and react in a closed container. After the reaction, it is dissolved in a benign solvent and then rotary evaporated to remove the residual solvent to obtain a terminal fluorinated poly-2-propyl-2-oxazine; C. Add hydrochloric acid for reaction. After the reaction, it is settled in a settling solvent, washed, and dried to obtain F-PPI.

4. The preparation method of the fluorinated polypropylene imine according to claim 3, wherein, In step A, the molar ratio of butyronitrile to propanolamine is 1:1 to 1.2; the reflux heating reaction conditions are to react at 110°C - 150°C for 2 - 4 days.

5. The preparation method of the fluorinated polypropylene imine according to claim 3, characterized in that, The extraction and drying treatment described in step A include: dissolving the product in a solvent, extracting with water to ensure complete removal of propanolamine; taking the lower organic layer, adding anhydrous MgSO4 for drying, filtering, taking the filtrate and rotary evaporating to obtain a crude product of 2-propyl-2-oxazine monomer; removing water from the rotary-evaporated 2-propyl-2-oxazine monomer by vacuum distillation, collecting the pure fraction, and adding anhydrous magnesium sulfate to obtain a completely dry 2-propyl-2-oxazine monomer.

6. The preparation method of the fluorinated polypropylene imine according to claim 5, wherein, The rotary evaporation is to first distill out the solvent at room temperature, and then raise the temperature to 35 - 55°C to distill out most of the butyronitrile to obtain a crude product of 2-propyl-2-oxazine monomer.

7. The method for preparing the fluorinated polypropylene imine according to claim 5, characterized in that, The vacuum distillation for water removal: Vacuum distill the crude monomer product until no liquid drips out, raise the temperature to 80°C, observe for 20 minutes to ensure no butyronitrile is distilled out, raise the temperature to 100°C, discard the first 2 mL of liquid, change the bottle, raise the temperature to 120°C, and collect the pure fraction.

8. The preparation method of the fluorinated polypropylene imine according to claim 3, wherein, The solvent described in step B includes acetonitrile, chlorobenzene or dichlorobenzene; the benign solvent includes dichloromethane, ethyl acetate, or ethanol; the temperature condition for the rotary evaporation is 30°C - 70°C.

9. The preparation method of the fluorinated polypropylene imine according to claim 3, characterized in that, In step C, the concentration of the hydrochloric acid is 6 - 12 mol / L; the reaction temperature is 60 - 100°C; the reaction time is 48 - 96 h; the settling solvent includes one or more of methanol, ethanol, ether, and acetone.

10. Use of the fluorinated polypropylene imine according to claim 1 or 2 in antibacterial aspects.

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