Publication Date

Summer 2020

Advisor(s) - Committee Chair

Ali Oguz Er (Director), Doug Harper, and Ivan Novikov

Degree Program

Department of Physics and Astronomy

Degree Type

Master of Science


Photosensitizing agents are the cornerstone of photodynamic therapy (PDT) that play essential role in deactivation process of multidrug resistant pathogens and tumor treatments. In this work we studied a photosensitizing agent made from mixture of silver nanoparticles (Ag NPs) and methylene blue (MB) which possess improved important characteristics like high photostability and high singlet oxygen yield. Ag NPs were synthesized by pulsed laser ablation technique in different aqueous solutions like Polyvinylpyrrolidone (PVP), citrate and Deionized (DI) water. The synthesized Ag NPs were characterized in depth using with transmission electron microscopy (TEM), UVVisible (UV-Vis), and photoluminescence (PL) spectra. Ag NPs were then combined with MB and used to eradicate the Gram-negative bacteria, Escherichia coli (E. coli), and Gram-positive bacteria, Staphylococcus aureus (S. aureus). MB and Ag NPs mixture was found to possess higher antimicrobial activity and thus were more effective in deactivating both Gram –positive and Gram-negative bacteria in comparison to individual exposure of MB and Ag NPs. Additionally, the antimicrobial effects varied with respect to the size of nanoparticles as well as the medium used for their synthesis. The data from this study supports the potential use of the proposed method in PDT where standard photosensitizers have limitations.


Bacteriology | Biological and Chemical Physics | Optics