Investigation of the effects of nanoparticles and apoptosis -inducing drugs on cells.

Abstract

The unique physical and chemical properties of nanoparticles that make them of interest for research and development are also the same properties that may hold potential health risks to humans and the environment. Understanding the effects of the physical and chemical properties of nanoparticles on their behavior in the living and natural environment will aid in both the development of nanoparticles for specific purposes and the understanding of potential side-effects of exposure. This thesis presents the characterization of organic nanoparticles using atomic force microscopy (AFM) and the patch clamp technique. Microscopy is a powerful technique for characterizing sample size, shape and morphology. Atomic force microscopy (AFM) is especially applicable to nanoparticle characterization, as it can obtain nanometer scale information in 3-dimensions in both air and fluid. For these reasons, AFM was also used to quantify the morphological response of cells exposed to apoptosis-inducing drugs (free drug) and nanoparticle-delivered drugs. AFM was used to quantify the rapid volume response of cells to apoptosis-inducing drugs within minutes of exposure. AFM was also able to identify morphological characteristics that would not be visible using light microscopy. All of the observed morphological changes occurred prior to activation of key biochemical time-points such as phosphatidylserine translocation, mitochondrial membrane potential change, caspase 3 activation and DNA fragmentation. The patch clamp technique has also shown great utility in characterizing the interaction of nanoparticles with living cells. This thesis presents the first published account of the use of the patch clamp technique to show that one class of nanoparticles, polycationic organic nanoparticles, induce nano-scale holes in cell membranes.