Behaviors and Persistence of Nanomaterials in Biomedical Applications

Chapter 2Nanomaterials

The behaviors of matter at the nanoscale are fascinating and completely different with respect to the bulk. In this chapter, we address this topic: in the first part, the intriguing and unexpected behavior of materials at the nanoscale are presented, while in the second part, an overview of the most popular nanomaterials and their general method of production is provided, focusing on wet chemical synthesis routes.

2.1 Physical Properties of Nanomaterials

Science and technology have been deeply revolutionized over the past decades, since when the controlled production of materials in the size range of 1–100 nm (referred to as nanomaterials) has been improved. Because of the small size, most of the physical, physiological and chemical properties of materials at the nanoscale are completely different from those of the bulk.

Indeed, within this size-range, features such as melting point, hardness, optical behavior, catalytic activity, or magnetic permeability become size-dependent. These peculiar behaviors are also ascribed to the surface-to-volume ratio, which decreases proportionally to the inverse particle size. A strictly related quantity is the dispersion, which is defined as ratio between the surface atoms and the total number of atoms (N) and scale as N^1/3.

A more rigorous interpretation is related to the number of direct atom’s neighbors, or coordination number. Considering a crystal lattice, it is easy to Figure that atoms at the surface, edges and ...