Investigating quantum dot toxicity by quantifying DNA polymerase activity with single molecule force spectroscopy

Student: Kathy Chaurasiya
Department: Physics
Advisor: Mark Williams

Abstract

Quantum dots (QDs) have widespread, revolutionary applications in medicine, but the toxicity of these nanoparticles is multifaceted and not well understood. Cytotoxicity due to QD interference in vital cellular processes will be investigated by examining the effect of cadmium telluride (CdTe) QDs on DNA polymerase III (DNAp III), the replicative polymerase in Escherichia coli (E. coli). Single-molecule force spectroscopy will be used to investigate the structure and functional mechanisms of this bacterial replicase. The difference in the elasticity of single- and double-stranded DNA will be utilized to measure the catalytic rate of α DNAp III as a function of the tension on the DNA template strand. This technique will provide a quantitative description of its catalytic activity and active site size, which is essential to a fundamental understanding of both bacterial and eukaryotic replicative polymerases. The activity of α DNAp III will then be measured in the presence of CdTe QDs to elucidate the effect of the nanoparticles on the catalytic rate and active site of the replicative polymerase, thus determining the extent and mechanism of QD cytotoxicity due to interference with DNA replication.