Utilizing an Epi-Fluorescent Optical Tweezer to Examine the Antimicrobial Effectiveness of Photochemically Prepared Cu-TiO₂ Nanoparticles

With antibiotic resistant microbes on the rise, the need for alternative antimicrobial materials has exponentially grown. Nanoparticles (NPs) have been increasingly used for these materials because of their small size and large surface area that allows for surface modification. Specifically, the use of semiconductor NPs for the reduction of metal ions has been explored, however, more work needs to be done to make the reduction of ions like Cu²⁺ more efficient. This work focuses on the mechanism and efficacy of incorporating Cu²⁺ into organo-metallic complexes for the photoreduction of Cu²⁺ on the surface of TiO₂. Additionally, the antimicrobial mechanisms of these NPs are discussed. It was determined that a non-diffusive mechanism was occurring thus the use of an epi-fluorescent optical tweezer was employed. Optical Tweezers are commonly used to trap and hold microscopic and sub-microscopic cells, particles and atoms through a highly focused IR laser beam. Single Cell Kinetics was then utilized to track the intensity of stained E. coli cells over time to probe the mechanism of cell death at the bacterial-nanoparticle film interface. Results show that there is an increase in bacterial cell death within 5 minutes of exposure.