Current applications of nanotechnology span from new materials for energy production or conversion (including photovoltaics, fuel cells, etc.), to a variety of consumer products and novel pharmacological formulations, and expand now extensively to biomedical research, medical diagnostics and therapy. In this book, a comprehensive overview of the progress achieved in the development of functional nanoparticles for novel bioanalytical techniques and assays, enhancement of medical diagnostic imaging, and a variety of cancer treatment therapies is presented, and future trends of nanotechnology applications in these areas are evaluated. Particular emphasis is placed on the functionalization of metal, semiconductor and insulator nanoparticles for targeting cancer cells, delivering drugs and chemotherapeutic agents, preventing or reducing body inflammation response, averting biofouling and cytotoxicity, and enabling cell membrane crossing. Progress in the development of nanoparticles enhancing the diagnostic imaging is discussed in detail and this includes nanoparticles for Magnetic Resonance Imaging (MRI), Computed Tomography (CT) scan, megasonic imaging, and novel photoacoustic and Raman imaging.