Design and Characterization of Novel Nanomaterials for Cancer Imaging and Therapy

The emergence of bionanotechnology has allowed the design of novel technological tools for a variety of biomedical applications. Despite the incompatibility of native semiconductor quantum dots with biological environment, this class of nanocrystals was among the first nanomaterials to demonstrate their use in biological labeling and imaging applications. In this thesis, new surface modification chemistry and synthetic strategies were developed to produce high quality biocompatible and bioconjugatable near-infrared emitting quantum dots for deep tissue in vivo imaging and detection applications. By carefully selecting a specific mixture of semiconductor elements to obtain a desired bandgap energy and optimizing the procedure for surface coating, successful synthesis of high quality, watersoluble, near-infrared emitting quantum dots were demonstrated. These developments allows for the use of quantum dots as alternative contrast agents for sophisticated biological imaging applications that are currently unachievable using conventional uorophores. In addition, using metallic nanoparticles, it was found that cells possess the ability to differentiate nanoparticles of various sizes upon their binding with specific membrane receptors. These receptors undergo rapid cellular internalization which altered their trafficking dynamics and down-stream signaling processes. The amplitude of such alteration was highly dependent on the size of the nanoparticle with most efficient internalization occurring at 40 nm - 50 nm size range. These observations raise important questions regarding the mechanisms governing similar processes and cell behaviours documented during viral infections. Whether such biological phenomenon are evolutionarily conserved as natural defense mechanisms to counter foreign invasion, or whether many of the known viruses are naturally selected to breach the primary defense of cells - the plasma membrane, remains to be elucidated. In summary, nanotechnology offers great promises for biological research and medicine. This thesis demonstrates the use of semiconductor and metallic nanostructures for imaging, detecting and administrating therapeutics in cancerous cells, tissues and animal models. Although the results presented in this thesis are preliminary, and the technologies demonstrated are still years away from practical use, these studies nevertheless, pave the way for future experimental researches within the field of nanomedicine, and provide insights into the understanding of the most fundamental yet highly complex processes in cell biology.Ph