Ultrashort Single-walled Carbon Nanotubes: A Platform for Medical Imaging and Therapy
Law, Justin Jonathan
Wilson, Lon J.
Doctor of Philosophy
Ultra-short single-walled carbon nanotubes (US-tubes) have been used to encapsulate various metal ions and small molecules for both diagnostic and therapeutic applications. Of the US-tube derivatives, one of the best characterized is the gadonanotube (GNT). GNTs are remarkable due to their greatly enhanced relaxivity, which is up to 40 times larger than current clinically available gadolinium based contrast. The work in this thesis explores the mechanisms contributing to this phenomenon. This is accomplished by using a series of closely related chelating ligands to explore the role of the coordination environment on the loading, retention, and relaxivity of gadolinium ions within the US-tubes. Further, the chelation system is applied to the positron emitting radioisotope <sup>64</sup>Cu and concurrent loading with gadolinium ions to produce bimodal imaging agents is discussed. In order to assess the viability of US-tubes as a platform for delivering medically relevant molecules, the biocompatibility of the US-tubes is explored. The cellular uptake and subcellular localization of the US-tubes is determined by Raman mapping and differences in US-tube aggregation and cellular response are analyzed. A strategy for enhancing water solubility of US-tube derivatives while retaining encapsulated ions is discussed. Finally, the heating properties of US-tubes in an external radiofrequency field are assessed to determine potential therapeutic applications.
Carbon Nanotubes; Magnetic Resonance Imaging; Positron Emission Tomography; Radiofrequency Heating