Synthesis And Properties Of Polymeric Quaternary Ammonium Salt And Cationic Antimicrobial Peptide

Bacterial infections are a serious health problem to the human population in our daily life.Since the finding of penicillin by Alexander Fleming,antibiotics have been introduced into clinical use to treat bacterial infections.However,the misuse and abuse of antibiotics may be associated with the development of microbial drug resistance.Therefore,large efforts have been made to discover and develop highly efficient antimicrobial agents.In recent years,cationic antimicrobial agents have gained great attentions due to their effective antimicrobial ability,good stability,broad-spectrum activities and other fine features.Cationic antimicrobial peptides(AMPs)and quaternary ammonium salts(QAS)are typical cationic antimicrobial agents and will be studied in the thesis.In this thesis,the quaternized poly(dimethylaminoethyl methacrylate)-grafted agarose(Agr-g-QPDMAEMA)copolymers were first prepared by atom transfer radical polymerization(ATRP)and quaternization with butyl bromide,and their antibacterial activities were studied.The tetraphenylethene-decorated AMP(TPE-AMP)was then synthesized via thiol-ene addition,and used for studying the interactions between AMPs and bacterial membrane and indicating the antibacterial activities of AMP via the fluorescence techniques.In the first chapter,the background information for the antimicrobial agents was summarized.In the second chapter,the materials and experimental sections for the preparation of QAS-and AMP-based antimicrobial agents were presented.In the third chapter,the as-synthesized Agr-g-QPDMAEMA)copolymers were characterized and their antimicrobial properties were assayed.In the fourth chapter,the as-obtained TPE-AMP was characterized.Its bacterial interactions were evaluated by confocal laser scanning microscopy(CLSM)and flow cytometry,and its antibacterial properties were verified by spread plate method and minimum inhibitory concentration(MIC)assay.In the last chapter,the work in this thesis was concluded.