History, introduction, and physiochemical properties of gold nanoparticles

Nanoparticles have been used in human civilization for a very long time, of which the earliest proof available to us is from 40,000 BC. The drastic changes in physical and chemical properties of particles when their size is bought down to nano size make it a very attractive application for research. After the industrial revolution and exponential growth in science and technology in the 1900s, the nanoparticles topic gained traction in the scientific community. Furthermore, various types of nanoparticles like carbon nanoparticles, inorganic nanoparticles, polymeric nanoparticles, and metallic nanoparticles were developed. These nanoparticles gained the attention of the pharmaceutical world due to their unique physicochemical properties, mostly gold nanoparticles. Therefore, various types of gold nanoparticles like gold nanosphere, nanorods, nanoshells, nanocage, and biofunctionalized gold nanoparticles were developed to create a drug delivery vehicle/system to work against various diseases mostly focusing on cancer and tumor cells and diseases specific to a particular organ as a targeted drug delivery system. Therefore, the efficient usage of the drug can be done. In this chapter, the potential usage of these gold nanoparticles in various diagnosis methods is also explored.