Preparation,Characterization And Application Of Pickering Emulsion Stabled By Parasin ? Antibacterial Peptide

Due to the irregular use of antibiotics,the process of bacterial resistance has been accelerated,and bacterial resistance to antibiotics has become a serious global health problem.Therefore,it is urgent to develop new antibacterial drugs to replace antibiotics to slow down the process of bacterial resistance.Antibacterial peptides have broad-spectrum bactericidal activities,and are not easy to cause drug resistance of pathogenic bacteria.Antibacterial peptides have great potential to replace antibiotics as a new type of drugs.However,the disadvantages of antibacterial peptides need to be improved,so this thesis attempts to construct a stable Pickering emulsion by antibacterial peptide nanoparticles.The antibacterial peptide Parasin ? interacted with or was conjugated with lecithin or chitosan to prepare nanoparticles.After homogenization,it became embedded.The antibacterial peptide pickering emulsion was expected to become an effective drug for slowing bacterial resistance in the clinic.The findings were as follows:1.Lecithin-embedded parasin ? antibacterial peptide nanoparticles(LPN)were prepared by ultrasound,and chitosan-embedded nanoparticles(CPEN)and shells were prepared by particle cross-linking method.Parasin ?-conjugated chitosan nanoparticles(PCN)were conjugated to glycans,and the chemical structure and intermolecular forces of the nanoparticles were analyzed by Fourier transform infrared and molecular docking.Scanning electron microscope,atomic force microscope,and cryo scanning electronen microscope(cryo-SEM)were used to observe the morphology and dispersion state of the nanoparticles,and nanoparticles with uniform particle size and difficult to aggregate were obtained.The results showed that there was a strong electrostatic interaction between parasin ? and lecithin,the formation of amide bonds in PCN,and the formation of SH in mercaptochitosan.LPN can form a uniform shape under the ultrasonic power of 600 W.Nanoparticles with a size of 30-60 nm,which were not easily aggregated,had an isoelectric point of pH 4.5 for LPN and CPEN.The encapsulation and load rates of parasin ? in CPEN were 76.2 and 53.5%,respectively,while in LPN they were 85.1 and 79.5%,respectively.2.LPNE,CPEN or PCN stabilized fish oil and water were prepared to form three Pickering emulsions of LPNE,CPENE,and PCNE.The droplet size distribution of the emulsion,the distribution of nanoparticles in the interfacial layer,and the antibacterial activity of the emulsion in vitro were evaluated.The results showed that when the concentration of nanoparticles increased from 0.1% to 0.2%,the stability of the three emulsions continued to increase,and the stability was better under alkaline conditions.The stability of CPENE in the three emulsions was the strongest.At a nanoparticle concentration of 0.15%,the encapsulation efficiency of parasin ? in CPENE,LPNE,and CPNE emulsions was 68%,43.5%,and 67.9%,respectively.Under neutral conditions(pH 7),the Zeta potentials of CPEN,LPNE,and PCNE are-39,57.7,and 2.97 mV,respectively.At pH 4.5(isoelectric point),LPNE and PCNE nanoparticles have the highest hydrophobicity and interface.Tends to bend toward the water phase.In E.coli and S.aureus,Pickering emulsion had a greater bacteriostatic effect on Gram-positive and Gram-negative bacteria than on Parasin ? through membrane lysis mechanism,which can cause serious bacteria agglomerate and lyse.3.To evaluate the therapeutic effects of three emulsions in peritonitis model,in order to explore the toxicity and antibacterial effect of emulsions in vitro and in vivo.The results showed that the three Pickering emulsions reduced the cytotoxicity to human hepatocytes and the hemolytic activity of rat red blood cells.In addition,Pickering emulsion had less effects on blood routine parameters,had no acute toxicity to Kunming mice.In the peritonitis model Kunming mice of E.coli,Pickering emulsion had a better therapeutic effects than parasin ? alone,and had more strong anti-inflammatory effects.4.Hematoxylin-eosin(HE)staining and Masson staining were used to analyze the effects of three emulsions on the histopathology of liver and heart of peritonitis mice.The results showed that the total pathological score(THIS)of CPENE emulsion was significantly reduced,and the liver and heart tissues had no obvious inflammatory cell infiltration and fibrosis.Therefore,the three CPENE emulsions were resistant to treatment in biomedical applications.