Preparation And Antibacterial Appliactions Of Polyurethane Micelles With A Dense PEG Brush Coroners

Polyethylene glycol(PEG)has been widely used in biomedical field due to its good biodegradability and biocompatibility.The surface PEG brushes of the material has excellent antifouling properties and is widely used in the field of biomaterials.In order to improve the density of PEG on the polyurethane micelles,our group designed and synthesized a polyurethane materials with pendant PEG attached on the hard segment(PEG-g-PU),which the surface of PEG-g-PU self-assemble micelles had dense PEG brushes.In addition,PEG incorporated as a soft segment(PEG-b-PU)or MPEG endcaped PU(PEG-c-PU)were prepared and self-assembled into micelles,the results shown that PEG-b-PU and PEG-c-PU micelles surface had no PEG brushes.Based on the results of the above studies,the PEG-g-PU micelles with a dense PEG brush on the surface were investigated for antibacterial/antifouling applications and compared with PEG-b-PU and PEG-c-PU micelles.The main works are as follows:(1)In order to solve the problem of cytotoxicity of small silver nanoparticles with excellent antibacterial property,we prepared a novel nanocomposites composed of silver nanoparticles decorated lipase-sensitive polyurethane micelles(PUM-Ag)with MPEG brush on the surface.The nanoassembly remained intact in the absence of bacteria and the silver nanoparticles were protected by the polymer matrix and PEG brush which show good cytocompatibility.However,in the presence of bacteria,the polymer matrix of nanocomposites is degraded by the activity of bacterial lipases.Afterwards,smaller silver nanoparticles were released which show enhanced toxicity to microorganisms.(2)The effects of PEG location on their surface charge switching activities,on the lipase triggered release of encapsulated drug,on the antibacterial properties of Tricolsan encapsulated three kinds of PU micelles(PEG-g-PU,PEG-b-PU and PEG-c-PU),and their killing efficiency against biofilms,were investigated.It was found that polyurethane micelles with pendant PEG attached on the tertiary amine groups(PEG-g-PU)shown pH sensitive surface charge switching properties while no obvious surface charge switching activities were found in the other two kinds of PU micelles.Triclosan loaded in PEG-g-PU micelles demonstrated more efficient on-demand drug release and higher antibiofilm activities than that encapsulated in the other two PU micelles.(3)The three kinds of PU micelles(PEG-g-PU,PEG-b-PU and PEG-c-PU)with or without loading of Triclosan were used as surface modification agents to render the substrate with antifouling and antibacterial activities,by using layer-by-layer assembly methods.The PEG-g-PU micelle-LBL multilayer films shown good antifouling activities against model bacteria due to the dense PEG brush.Furthermore,the pH sensitive PEG-g-PU micelle-LBL multilayer films degradation could remove the surface-attached bacteria and show “self-cleaning” performance.The Triclosan loaded PEG-g-PUM modified surface demonstrated excellent antibacterial performance which released the payloads in the presence of lipase and released the entire micelles from surface.