A Review on Metallic Gold and Silver Nanoparticles

Recent developments in material synthesis involve avariety of physical and chemical approaches which has substantially influenced the field of nanotechnology. These strategies play a significant role in many prospects such as synthesis of nanoparticles of variable shapes and uniform particle size distribution. Toxic chemicals in these strategies for the synthesis of metal nanoparticles create hazardous concerns for the environment. In contrary, the biological approach includes the use of bioactive components which are highly biodegradable in nature. Hence biological approach is considered as a promising method for the eco-friendly synthesis of noble metal nanoparticles. Although these noble metal nanoparticles can be synthesised in various forms such as nano-sols, nano-colloids, nano-crystallines, nanorods, nanotubes and nanowires using a variety of physical as well as chemical approaches. Besides their shape and morphology, the size of noble metal nanoparticles should be efficiently tailored to achieve the desired medical application. The increase in surface area increases the possibility of causing the aggregation of nanoparticles which limit their functionalities. The surface functionalization of noble metal nanoparticles was done using chemical dispersants such as surfactants or polyelectrolytes to avoid the aggregation. This functionalisation improves the stability of the noble metal nanoparticles but at the same time it alters the surface chemistry of the nanoparticles. It is crucial for producing the nanoparticles in such a way that they could be size controlled, inexpensive and eco-friendly. The objective of this review is, therefore, to reveal the past and present scenarios, specifically the possibilities of noble metal nanoparticles in applications. Furthermore, it also documents the detailed information about the strategies involved in the use of plant extracts as reducing agents in the synthesis of metal nanoparticles and the incorporation of metal nanoparticles into polymeric materials for environmental applications. This review paper mainly summarizes the various synthesis methods of gold and silver nanoparticles and their applications in biomedicine.