Photonic and Magnetic Nano- and Micro-Particles for Biomedical Applications: Detection and Distruction of Bacterial and Cancer Cells.

Abstract

Recently, many advances have been made on the use of micro- and nano-particles for photothermal therapy and photodynamic therapy, as well as for bacterial detection and growth dynamics. This thesis includes three projects on the utility of activated particles towards the eradication of tumor cells and bacteria. Recently our laboratory developed a biodegradable nanoparticle, copolymerized from acrylamide and a coomassie blue derivative. In this work we investigated the capability of the coomassie blue polyacrylamide (CB-PAA) nanoparticle to induce tumor cell death photothermally. Specifically, the dependence of cell death on mass concentration of nanoparticles, incubation time with nanoparticles, and the exposure time and intensity of the light source were determined. These CB-PAA nanoparticles were able to cause significant cell death, up to 97%, at fluencies as low as 61 J/cm2, when incubated with 1.2 mg/mL CB-PAA nanoparticles. Photodynamic cell kill of bacteria has been extensively studied as an alternative treatment to antibiotics. Previously, methylene blue loaded polyacrylamide nanoparticles have been shown to cause cell death in various bacterial strains. In this work, we investigated a methylene blue molecule covalently linked to polyacrylamide nanoparticles to determine if it could be used as a photodynamic agent on Escherichia coli O157:H7. A major goal was to determine if any increase in methylene blue loading by covalent linkages would increase mortality of the cells. However, this alternative approach to methylene loaded nanoparticles showed no cell death. The possible reasons for less activity are discussed. Bacteria detection and monitoring of their cell growth are important for determining the correct antibiotic to be administered for an infection. An innovative approach from our laboratory, involving the use of nonlinear rotation of magnetic microparticles, has led to the ability to detect binding events of a single bacterium. We showed a decrease in average rotation rate by a factor 3.8 when a bacteria was bound to the surface of the microparticle. This opened the way towards a simple method of monitoring cell growth and its application for rapid determination of drug sensitivity, e.g. antibiotic susceptibility.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102445/1/rongsmit_1.pd