41 - Surface modification of inorganic nanoparticles by organic functional groups

Abstract

This chapter focuses on the attachment of organic functional groups on the surface of inorganic nanoparticles and proposes the chemical modification of the surface of nanoparticles to realize better handling of nanoparticles. Most noble metalnanoparticles including gold, silver, copper, palladium, platinum, and nickel can be modified with thiols. Metal oxides have various properties including electron transport, semiconducting property, ferromagnetism, giant magnetoresistance, luminescence, ferroelectric property, and catalysis, and the incorporation of these properties of metal oxides into nanoscale devices requires two techniques, which include synthesis of metal oxide nanoparticles and their surface modification. Simultaneous synthesis and modification of metal oxide nanoparticles are necessary as nanoparticles easily aggregate together irreversibly. During hydrothermal synthesis, the growth of metal oxide nanoparticles proceeds by the dehydration reaction between surface hydroxyl groups and metal hydroxides. Thus surface modification through chemical bonding between the surface hydroxyl groups on the surface of metal oxide nanoparticles and organic reagents during the synthesis are proposed. This results in surface-modified metal oxide nanoparticles covered with alkyl chains, which makes the surface of metal oxide nanoparticles hydrophobic. This result confirms that the synthesis of metal oxide nanoparticles in the presence of organic reagents produces the surface-modified metal oxide nanoparticles. The surface-modified nanoparticles can bind with biomolecules as well as inorganic materials, and the hybridized nanoparticles have both inorganic properties and biological specificity. The alignment of metal nanoparticles on a ladder structure of deoxyribonucleic acid (DNA) through hybridization between nanoparticles and DNA single strands is also discussed.