An Investigation into the Interaction of Various Salt Ions with DNA Topoisomerase IA during the Relaxation of Negatively-Supercoiled DNA.

Topoisomerases are enzymes that change the topological state of DNA by catalyzing the cleavage, subsequent strand passage and religation of either one or both strands of DNA during DNA replication and transcription. This research thesis focused on Escherichia coli DNA topoisomerase IA, an enzyme largely responsible for the maintenance of supercoiling and the specific relaxation of negative supercoils in E. coli DNA. The various types of topoisomerases and their functions were discussed. As a basis for this paper, some of the structural properties not yet determined in topoisomerase IA were mentioned with respect to the catalytic mechanism. A description was given of the methods used for laboratory research, Monte Carlo simulations. The goals of this research, both short-term and long-term, were also discussed. Known background information about topoisomerase IA was given in detail with regard to the enzyme’s structure and catalytic mechanism, followed by a discussion on the interaction of ions with the enzyme throughout its catalytic mechanism. The results of Monte Carlo simulation data were presented in the thesis, and a discussion on these results was given along with the future hopes of this important research

Dielectrophoretic Trapping of Carbon Nanotubes for Temperature Sensing

Conventional sensors are rapidly approaching efficiency limitations at their current size. In designing more efficient sensors, low dimensional materials such as carbon nanotubes (CNTs), quantum dots, and DNA origami can be used to enable higher degrees of sensitivity. Because of the high atomic surface to core ratio, these materials can be used to detect slight changes in chemical composition, strain, and temperature. CNTs offer unique advantages in different types of sensors due to their electromechanical properties. In temperature sensing, the high responsiveness to temperature and durability can be used to produce an accurate, reliable sensor in even extreme temperatures. This study aimed to utilize CNTs to reliably produce a temperature sensor in an easily reproducible method. CNTs were trapped and immobilized using dielectrophoresis to bridge two gold nanoelectrodes on a sapphire substrate. The fabricated device showed high sensitivity to temperature variation, with a measured resistive sensitivity of 2.96 E-3/K, a higher sensitivity than similar thin film sensors. This study will help further development of CNT-based temperature sensors