Abstract

Nanotechnology, which has been heralded as the next great technological revolution, is the engineering or manipulation of matter at or near the atomic level [1,2]; essentially, nanotechnology is building objects atom by atom and molecule by molecule. A key building block of this technological field are nanoparticles [3]. Nanoparticles are defined as particles with a diameter, or dimension, between 1 and 100 nm (nanometers). For reference, a nanometer is one billionth of a meter (10⁻⁹ m). In comparison, a human hair is approximately 80,000 nm in diameter, while a water molecule is only 0.3 nm across. Nanoparticles are in fact a class of particles of specific size more commonly referred to as colloids [4]. They have unique properties that distinguish them from other larger bulk materials having similar chemical compositions. These unique properties are largely attributed to the size effect phenomena [2]. As particle size approaches or decreases below 100 nm, the surface area-to-mass ratio increases dramatically, meaning that the bulk of a particle’s atoms are at the surface. This makes nanoparticles highly surface reactive. Another size effect is that quantum effects become much more significant for nanoparticles, which affects their optical, electrical, and magnetic properties [2,5].