Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biomedical Engineering

Supervisor

Jun Yang

Abstract

In this thesis, active and passive antimicrobial methods have been applied to fabricate antifouling surfaces. In the first study, we reported the synthesis and characterization of neat TiO2 and Ag-TiO2 composite nanofilms prepared on silicon wafer by sol-gel method. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination. The advantage of Ag-TiO2 nano-composites is to expand the nanomaterial’s antibacterial function to a broader range of working conditions. In the second study, we reported the synthesis, characterization and environmental application of nitrogen doped TiO2 photocatalyst in the form of powder and film. TiO2 photocatalysts were synthesized by hydrolysis of titanium tetra-isopropoxide in the presence of urea as nitrogen source. The visible light induced photocatalytic inactivation of bacteria (Escherichia coli) with the obtained nano-powders and nano-films was tested.

In the following study, we reported the successful formation of a titanium dioxide (TiO2) layer on butyl rubber (BR) substrate, cotton sheet and silicon wafer surfaces by using modified liquid phase deposition (LPD) method at mild environmental conditions. Various synthetic conditions were studied to control the morphology and nanostructures of the deposited TiO2 coatings. Superoleophobic TiO2 coatings were prepared after surface fluorination. The formed TiO2 coatings showed excellent antibacterial adhesion ability.

Superoleophobic surfaces, which are thought to limit bacterial contamination, were fabricated by an easy spray method. The surface of any polymers can be made superoleophobic using the following simple three-step process: (1) the spraying of polymer-nanoparticle mixtures; (2) cross-linking the coating to the substrate; and (3) chemical modification of the outer surface by perfluorosilane. Superoleophobicity is achieved by the combination of re-entrant and convex morphology of multiscale agglomerates produced by nano-particles embedded in polymer matrix and surface fluorination. Preparation parameters were optimized. Surface characterizations were extensively studied on the surface morphology, roughness and chemical compositions of the composite coatings with different nanofillers loading. The superoleophobic coatings presented excellent resistance to non-specific protein adsorption and show antibacterial adhesion. It is a promising material for biomedical and industrial applications.

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