A nanostructure is a structure of intermediate size between microscopic and molecular structures. Nanostructural detail is microstructure at nanoscale.

In describing nanostructures, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale. Nanotextured surfaces have one dimension on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length can be far more. Finally, spherical nanoparticles have three dimensions on the nanoscale, i.e., the particle is between 0.1 and 100 nm in each spatial dimension. The terms nanoparticles and ultrafine particles (UFP) are often used synonymously although UFP can reach into the micrometre range. The term nanostructure is often used when referring to magnetic technology.

Nanostructures for oral medicine can efficiently encapsulate drugs at high concentrations cross the cell membrane and release the drugs at the target site in a controlled manner for a prescribed period of time. Nanostructures are used as sustained delivery carriers in chronic therapies to reduce the frequency dose/dosing, minimizing side effects and increasing patient compliance. The focus of this chapter is to provide an overview of the role of nanostructures for oral medicine like synthesis, characterization, drug delivery mechanisms, and in vitro and in vivo techniques of the biodistribution and bioimaging of nanoparticle. However, stability, bioavailability, and solubility in the gastrointestinal tract create a challenge in the preparation of these nanostructures. This chapter sheds light on oral delivery