Green Synthesis of Nanomaterials Using Biological Routes

Abstract

Solution-based chemical synthesis of nanomaterials has a long history and has dominated the nanosphere with established protocols for synthesizing particles with excellent control over shape, size, and properties. With the development of chemical methods, the concern for a negative impact on the environment is also heightened. This has led scientists to develop green environment friendly routes for nanomaterials synthesis. Interestingly, nature has evolved numerous strategies for fabricating materials at the nanoscale through elegant and artistic ways that show high level of hierarchical ordering. One of such strategies evolved in nature is the important role of microbes in bioremediation. Microorganisms such as bacteria, fungi, algae, and plants are known for their inherent ability to withstand high concentrations of toxic metal ions through specific resistance mechanisms and therefore these are commonly employed toward remediation of different metal ions. Conversely relatively few organisms are known to produce nanomaterials in their natural habitats with examples including accumulation of gold in algal and bacterial cells, magnetite in magnetotactic bacteria, ZnS in sulfate reducing bacteria, etc. Although, these biological organisms are known for withstanding high concentrations of metal ions, the possibility of deliberately exploring these microbes as nano-factories (similar to the commercially applied fermentation technology that is now used for large-scale synthesis of enzymes, drugs, etc.) for nanomaterials synthesis is a recent phenomenon. A great deal of work has been performed in this emerging area of bionanotechnology with organisms like bacteria, fungi, and plants being regularly employed for the synthesis of a wide variety of nanomaterials ranging from metals and metal oxides to metal sulfides. This chapter will provide readers with information on some of the work encompassing this new green technological route on nanomaterials synthesis.