Preparation And Antibacterial Properties Of Brush Polymer Coatings With Dextran Backbones And Pseudo-zwitterionic Side-chains

Implantable medical device-associated infections(DAIs)caused by bacterial adhesion and biofilm formation have threatened the health and lives of patients.Multifunctional antimicrobial polymer coatings are gaining increasing interest due to their chemical and topological versatility,the development of controlled polymerization methods,and good processability.Antimicrobial polymer coatings with antifouling and bactericidal properties show great potential to solve the problem of DAIs,but simultaneously improving surface bactericidal and antifouling properties remains a challenge.To address this challenge,this thesis proposes the preparation of brush-shaped polymer coatings with hydrophilic backbones and cationic side chains.The main contents of the thesis are as follows:In Chapter 1,the prevalence of the problem of DAIs and the reasons for their generation are firstly discussed,followed by the types of antimicrobial surfaces and the progress of domestic and international research to address DAIs.In Chapter 2,a brush-shaped polymer coating(Dex-KE)with dextran(Dextran)as the main chain and pseudo-amphiphilic ions as the side chains was designed,while brush-shaped polymers with hydrophobic main chain pseudo-amphiphilic side chains were prepared.The surface of polydimethylsilane(PDMS)was modified by the co-deposition of poly dopamine(PDA)and dopamine(DA).The molecular structure,elemental composition hydrophobicity and surface morphology of the modified surface were characterized by Fourier infrared spectroscopy(FTIR),photoelectron spectroscopy(XPS),water contact angle measurement(WCA),and scanning electron microscopy(SEM),respectively.Biological experiments showed that the hydrophilic backbone brush polymers showed stronger surface antibacterial properties than the hydrophobic backbone brush polymers.In addition,the results of subcutaneous implantation experiments in mice showed that the Dex-KE coating has excellent anti-tissue infection properties and histocompatibility.In Chapter 3,brush-shaped polymers containing phenylalanine hydrophobic units in the side chains(Dex-KEF)were prepared and antimicrobial coatings were prepared using the dopamine deposition technique.The results showed that the incorporation of hydrophobic units improved the initial bactericidal efficiency and cell adhesion properties of the coatings.In Chapter 4,the current work is outlined and summarized,problems and possible solutions for the current design are presented,and future developments are envisioned.In summary,a series of polypeptides with sulfhydryl-containing end groups of different components and chain lengths were synthesized in this paper using controlled ring-opening polymerization and reduction reactions,which were attached to a dextran backbone modified by maleic acid via Michael addition reactions.The effects of structural parameters such as the hydrophobicity of the main chain,the degree of side-linked branching,chain length and hydrophobic group content on the antimicrobial properties were investigated,enriching the variety of antimicrobial polymer coatings and providing new ideas for the design and preparation of antimicrobial surfaces.