PREPARATION AND CHARACTERIZATION OF STIMULI-RESPONSIVE LAYER-BY-LAYER FILMS FOR FOOD TECHNOLOGY APPLICATIONS

Date

2024-9-6

Author

Güren, Ayşe

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In the first part of this thesis study, zwitterionic block copolymer micelles of poly[3-dimethyl(methacryloyloxyethyl)- ammonium propanesulfonate]-block-poly[2-(diisopropylamino)-ethyl methacrylate] (βPDMA-b-PDPA) with zwitterionic βPDMA-corona and pH-sensitive PDPA-core were prepared through pH-induced self-assembly of βPDMA-b-PDPA in aqueous solution. Micelles were found to be stable between pH 6.5-7.4. Decreasing temperature induced inter-micellar interactions due to enhanced association among coronal chains which became relatively more hydrophobic around UCST (upper critical solution temperature) of βPDMA. Taking this information as a basis, ultra-thin multilayer films of βPDMA-b-PDPA micelles and alginate were prepared at pH 7.0 and 25 ℃ through layer-by-layer (LbL) self-assembly technique. Decreasing temperature provided higher film thickness, while it did not have a pronounced effect on film stability. On the other hand, the stability of multilayers (25 ℃) enhanced at decreasing temperature at both acidic and basic pH. In the second part of the study, the information generated about preparation of βPDMA-b-PDPA micelles/alginate multilayers was used to modify the surface of alginate hydrogels. βPDMA-b-PDPA was loaded with curcumin (CUR) and self-assembled with alginate at the surface of Salmonella enterica ssp. enterica (Salmonella) Enteritidis bacteriophage (MET_P1_001_43) containing alginate hydrogel. CUR release from hydrogels was examined at pH 7.0/7 ℃ and pH 5.0/7 ℃. CUR release was faster at acidic pH. CUR release at 37 ℃ couldn’t be quantified due to partial release of alginate chains from the hydrogel matrix. Antibacterial activity studies against Salmonella Enteritidis were performed at pH 7.0 and pH 5.0 at 37 ℃. Bacteriophages and CUR acted in a combinatorial manner at pH 7.0. Although CUR loaded βPDMA-b-PDPA micelles did not impart antibacterial activity to alginate hydrogels when they are used alone, they enhanced the antibacterial activity provided by phages at pH 7.0. Overall, the results obtained in this thesis study may form a basis for preparation of antibacterial surfaces for food packaging and biomedical applications.

Subject Keywords

Block Copolymer Micelles, pH-Responsive, Bacteriophage, Antibacterial Activity, Curcumin

URI

https://hdl.handle.net/11511/111417

Collections

Graduate School of Natural and Applied Sciences, Thesis