Construction Of Bacterial Coating Based On Imidazole Quaternary Ammonium Salts And Its Quorum Sensing-mediated Antibacterial Mechanism

The identification and inactivation of pathogenic microorganisms has always been a great challenge in the prevention and control of infectious diseases caused by microorganisms.In recent years,cationic polymers have attracted great attention of researchers because of their easy modification,amphiphilic and remarkable broad-spectrum antibacterial effect.However,the abuse of broad-spectrum antibiotics may greatly increase the possibility of bacterial drug resistance.Therefore,the development of targeted antimicrobials or giving antimicrobials targeting specificity to regulate flora balance has of far-reaching significance for solving the problem of bacterial drug resistance and better maintaining the balance of human micro-ecological environment.Hence,the research in thesis is as follows:We used imidazole quaternary ammonium salts and cucurbituril[7]to form a complex p BPI?CB[7]（PC）via host-guest interaction,which was grafted on the surface of Escherichia coli（E.coli）cells by atomic free radical polymerization（ATRP）to construct an in situ polymerization system to obtain E.coli@PC（E@PC）complex.Using 100 nm and 500 nm silica（Si O₂）,Staphylococcus aureus（S.aureus）,ampicillin-resistant Escherichia coli（E.coli p UC19）and methicillin-resistant S.aureus（MRSA）as templates,four kinds of surface coating polymers Si@PC,S@PC,EA@PC and MS@PC were prepared by the same synthesized method of E@PC,respectively.E.coli and S.aureus were selected as the model bacterium,the plate counting method and living cell staining method were used to verify the antibacterial performance of E@PC.Based on the interaction between host and guest,it is proved that E@PC can reversibly turn on and turn off the antibacterial activity as needed.At last,the antibacterial mechanism of E@PC was systematically studied by means of the changes of bacterial morphology,cell membrane potential,and the leakages of DNA and ion.The specific recognition and strong antibacterial properties of four kinds of as-prepared"bacteria@PC"were explored by the methods of plate counting and minimum inhibitory concentration（MIC）.In addition,the one-step inactivation approach was used to knock out the genes related to E.coli producing quorum sensing（QS）signal and encoding flagellin,then the E.coli treated by knocking-out gene was used as an indicator to explore its sensitivity to E@PC.The results suggest that the specific bactericidal activity of the complex E@PC to template bacteria is due to QS between bacteria.