Recently, technological advances have greatly increased, generating the development of nanotechnology, which is responsible for the design of structures and materials in the nanometer scale. This creates one of the most important cutting-edge sciences, integrating physics, chemistry, engineering and biology sciences. Specifically the integration with biology results in a new science called nanobiotechnology, specifically nanomedicine, which has the goal of mainly looking for more precise molecular diagnostic and prognostic processes, as well as the new design of drugs in the personalized medicine field. On the other hand, at molecular level in medical research, the nanoparticles are most commonly used as tools. Molecular diagnostics uses gold nanoparticles, paramagnetic nanoparticles and quantum dots, which can be used for the diagnosis and treatment of several diseases, including cancer. Quantum dots are the most promising tools for diagnosis and therapy in cancer research.