Biotechnology is the science and technology of building functional structures and devices. In Greek, "Biotechnology" derives from the bio which means life and technologia means systematic treatment of an art or craft. Nanostructured inorganic, organic, and biological materials may have existed in nature since the evolution of life started on Earth. Some evident examples are micro-organisms, fine-grained minerals in rocks, and nano size particles in bacteria and smoke. From a biological viewpoint, the DNA double-helix has a diameter of about 2 nm (20 angstrom) while ribosomes have a diameter of 25 nm. Atoms have a size of 1-4 angstrom; therefore nanostructured materials could hold tens of thousands of atoms all together. Moving to a micrometer scale, the diameter of a human hair is 50-100 _m. Advancements in microscopy technology have made it possible to visualize images of nanostructures and have largely dictated the development of nanotechnology.
