With the recent development of efficient and reproducible methods for synthesis, stable aqueous dispersions of individual particles can be prepared, in which the particle sizes can be accurately adjusted from a few nanometers to a few tens of nanometers [1]. Provided that their physical and chemical surface properties can be suitably adapted, these objects are small enough to circulate within the human body without risk of causing an embolus, since the finest capillaries (those of the lungs) have a minimal internal diameter of 5 μm. They can also escape from the blood compartment by windows of diameter around 100 nm in certain epithelia with permeability defects, such as those located in tumours and centers of infection, whereby they may then accumulate in such tissues. Furthermore, the smallest particles can migrate from the cardiovascular system into the lymph system. Finally, under the right conditions, they can enter cells and their various compartments. They should quickly become indispensable in the field of biological labelling, image contrast enhancement, the delivery of active principles, and the treatment of many different pathologies, by virtue of their novel physical properties [2, 3].Research scientists and physicians thus have at their disposal new tools for understanding biological processes, strengthening the value of medical diagnosis, and even developing new therapeutic strategies. And so a new and largely crossdisciplinary field of investigation was born: nanomedicine, which we may define as molecular scale surveillance, repair, construction, and control of human biological systems by means of nanoscale devices [4].< Leer menos