ABSTRACT
INTRODUCTION Gold has received much interest in the field of biomedical engineering. The use of gold as a key component in biodiagnostic and therapeutic fields has emerged primarily over a period of three decades, though it has been used for centuries for artistic purposes. Gold is known to be the main ingredient for the preparation of an ancient Roman elixir of life. An example of a historical use of gold was in the coloring of glass during the 17th century to produce intense shades of yellow, red, or brown depending on the concentration of gold. In 1842, colloidal gold was used in chrysotype, a photographic process to record images on paper. During the 19th century, the pure form of gold called activated gold, due to its inert behavior to harsh environments, was prominently employed for catalysis (1). With the advent of numerous tools, techniques, and concepts related to nanotechnology, in combination with the inherent property of gold to form functionalized bioconjugates via simple chemistry, gold has found importance in various biodiagnostic and therapeutic applications (2-6). Herein, we detail the progress made in the functionalization of gold surfaces, both planar and particulates, at the nanoscale for diagnostic and therapeutic applications.
