Nanostructures, owing to their shape and size, exhibit unique electrical, optical, thermal and magnetic properties in contrast to their bulk counterparts. Hence they attract great attention in various spheres of research. They can be synthesized using top-down or bottom-up approaches respectively. In top-down approach, macroscopic materials are subjected to various processing techniques such as ball milling, lithography etc. to form nanomaterials. Whereas in the bottom-up approach the process starts at the atomic level leading to self-assembly owing to physical forces prevalent at atomic level to form larger stable structures. Some of the bottom-up approaches include epitaxial growth, atomic layer deposition, colloidal dispersion, electrospinning. The bottom-up approaches are economical than the top-down approaches.
