Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Middle East Technical University, Faculty of Arts and Sciences, Department of Chemistry, Turkey
Approval Date: 2019
Thesis Language: English
Student: SİNEM ULUSAN
Principal Supervisor (For Co-Supervisor Theses): İrem Erel Göktepe
Co-Supervisor: Sreeparna Banerjee
Abstract:In this study preparation of ultra-thin coatings of zwitterionic block copolymer micelles and a comparison of their protein adsorption, adhesiveness and anti-bacterial properties as well as adhesiveness against osteoblast-like cells were studied. Zwitterionic block copolymer micelles were obtained through pH-induced self-assembly of poly[3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate-b-2-(diisopropylamino)ethyl methacrylate] (βPDMA-b-PDPA) at pH 7.5. βPDMA-b-PDPA micelles with zwitterionic βPDMA-corona and pH-responsive PDPA-core were then used as building blocks to prepare either 1-layer or layer-by-layer (LbL) assembled multilayer films together with Hyaluronic Acid (HA), Tannic Acid (TA) or poly(sodium 4-styrene sulfonate) (PSS). Protein adsorption tests showed that 3-layer βPDMA-b-PDPA micelles/HA films were the most effective in reducing the adhesion of BSA, lysozyme, ferritin, and casein. In contrast, βPDMA-b-PDPA micelles/TA films were the most attractive surfaces for protein adsorption. Bacterial anti-adhesive tests against a model Gram-negative bacterium, Escherichia coli and a model Gram-positive bacterium, Staphylococcus aureus were in good agreement with the protein adsorption properties of the films. The differences in the anti-adhesive properties between these three different film systems were discussed within vi the context of chemical nature and the functional chemical groups of the polyanions, layer number and surface morphology of the films. Multilayers were found to lose their anti-adhesiveness in the long-term. However, by taking advantage of the pH-responsive hydrophobic micellar cores, an anti-bacterial agent could be loaded into the micelles and multilayers could exhibit anti-bacterial activity in the long-term especially at moderately acidic conditions. In contrast to anti-adhesive properties, no significant differences were recorded in the anti-bacterial properties or osteoblast adhesive properties between the different film types.