Surface Modification of Metallic Nanoparticles

Abstract

Nanomaterials are particles with various characteristic shapes, dimensions ranging from zero-dimensional to three-dimensional structures, and sizes ranging between 1 nm and 100 nm. The properties of nanomaterials are due to this small size, which thereby increases their surface area and reactivity. This nanoscale size of particles results in different properties than those of the corresponding bulk material, such as mechanical strength, optical properties, magnetic susceptibility, and electrical conductivity. The specific surface area of a spherical nanoparticle increases by 1/10; modest-size nanoparticles have a high surface-to-mass ratio and hence a high interfacial energy. The high reactive surface area of the nanomaterial can be modified by the choice of application for a certain industry. The most widely used nanomaterials in various industries are metals and metal oxides due to their unique changes in properties and characteristic features compared with their respective bulk materials. Because of their high reactivity and high available surface area, nanoparticles usually tend to be unstable. To avoid aggregation, it is often recommended to stabilize or functionalize such nanoparticles to improve the shelf life of a nanomaterial. Thus, modification of the surface of nanoparticles is an important chemical step that adds value to the final product. This chapter discusses various methods of surface modification, how metals and metal nanoparticles can be protected by using surfactants, and how the biocompatibility of these ligands can be used to introduce novel functionalities that broaden the range of application.